JP2014063700A - Coater, coating method and process of manufacturing organic functional element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coater capable of reducing film thickness irregularity caused by non-uniformity of an evaporation rate of a solvent during coating or immediately after coating.SOLUTION: The coater includes a stage on which a substrate is installed, a nozzle at which a discharge port that discharges a coating liquid onto the substrate is formed, a movement mechanism capable of relatively moving the stage and the nozzle in a surface direction of the substrate, and an air flow generating part that generates an air flow near the nozzle, where the air flow generating part includes an opening that extends in the direction of the nozzle movement, and generates a sheet-like air flow from the opening to the neighborhood of the nozzle.

Description

  The present invention relates to a coating apparatus that forms a coating film by applying ink to a substrate on a stage using a nozzle, a coating method using the coating apparatus, and a method for manufacturing an organic functional element using the coating apparatus. .

  In recent years, as a next-generation display device following a liquid crystal display element (LCD), a light-emitting element type display panel in which self-light-emitting elements such as organic electroluminescence elements (hereinafter abbreviated as “organic EL elements”) are two-dimensionally arranged is provided. Research and development of light emitting devices are underway.

  The organic EL element includes an anode electrode, a cathode electrode, and an organic EL layer having a light emitting layer, a hole injection layer, and the like formed between the pair of electrodes. In the organic EL element, light is emitted by energy generated by recombination of holes and electrons in the light emitting layer.

  As a process for forming a light emitting layer, a hole injection layer, etc. of such an organic EL element, a liquid organic material is passed through a nozzle in a groove between partition walls formed so as to surround a transparent electrode provided on a glass substrate. A nozzle printing method in which an EL material is poured and applied is used. (For example, refer to Patent Document 1.)

JP 2002-75640 A

  The ink ejected from the nozzles is dried and solidified as the solvent contained in the ink evaporates in the pixel formation area on the substrate to form a coating film, but the ink ejection from the nozzles is moved relatively between the stage and the nozzles. Thus, the coating is continuously performed, and the solvent atmosphere during coating does not become uniform. For this reason, the evaporation rate of the solvent contained in the ink becomes non-uniform, which affects the film shape of the organic EL layer formed in the pixel formation region, and it is difficult to control the film thickness uniformly. It was.

  If the film thickness of the organic EL layer becomes non-uniform, the light emission starting voltage during the light emitting operation of the organic EL element and the wavelength of light emitted from the organic EL layer (that is, chromaticity during image display) are designed values. Therefore, a desired display image quality cannot be obtained, and an excessive light emission driving current flows in a region where the organic EL layer is thin, so that the ratio of the light emitting region in the display panel (pixel forming region) ( There has been a problem that the so-called aperture ratio) is lowered and the organic EL layer (organic EL element) is remarkably deteriorated so that the reliability and life of the display panel are lowered.

  The present invention has been made in view of the above-described circumstances, and is a coating apparatus that can reduce film thickness unevenness due to non-uniformity in the evaporation rate of a solvent during or immediately after coating, and coating using the coating apparatus It is an object to provide a method and a method for producing an organic functional element using the coating apparatus.

  According to a first aspect of the present invention, a stage on which a substrate is installed, a nozzle in which a discharge port for discharging a coating liquid is formed on the substrate, and the stage and the nozzle are relatively movable in the surface direction of the substrate. A moving mechanism that includes an airflow generating unit that generates an airflow in the vicinity of the nozzle, the airflow generating unit having an opening that extends in the moving direction of the nozzle, A sheet-like air current is generated in the vicinity of the nozzle from the opening.

  2nd invention is a coating device of 1st invention, Comprising: The said airflow generation part is provided with the 1st airflow generation part and the 2nd airflow generation part, The said 1st airflow generation part and said 2nd The airflow generating portion is disposed so as to be opposed substantially parallel to each other across the area discharged by the nozzle.

  A third invention is the coating apparatus according to the first invention, and includes a plurality of the nozzles and the airflow generation units, and the airflow generation units are arranged substantially opposite to each other with the nozzles interposed therebetween. .

  A fourth invention is a coating apparatus according to any one of the first to third inventions, wherein the air flow generation unit is provided in a holding unit that supports a nozzle head, regardless of movement of the stage and the nozzle. The airflow is generated at a fixed position.

  A fifth aspect of the invention is the coating apparatus according to any one of the first to third aspects of the invention, wherein the air flow generation unit is provided in a nozzle holding unit, and the air flow generation unit moves in conjunction with the movement of the nozzle. .

  A sixth invention is a coating apparatus according to any one of the first to fifth inventions, wherein the airflow is an inert gas.

  According to a seventh aspect of the invention, a stage on which a substrate is installed, a nozzle in which a discharge port for discharging a coating liquid is formed on the substrate, and the stage and the nozzle are relatively movable in the surface direction of the substrate. And a coating method that coats and forms the coating liquid on the substrate using a coating apparatus that includes the moving mechanism. The coating film is formed by discharging the coating liquid from the nozzle. And generating a sheet-like airflow extending in the nozzle moving direction in the vicinity of the nozzle.

  An eighth invention is a coating method according to the seventh invention, and includes a step of generating a first airflow and a second airflow that face each other across an area discharged by the nozzle.

  A ninth invention is a coating method according to the seventh invention, wherein the coating film is formed by discharging the coating liquid from the plurality of nozzles, and the plurality of nozzles facing each other with the plurality of nozzles interposed therebetween. Generating an air current.

  A tenth invention is a method for producing an organic functional element having a plurality of organic functional layers, comprising the step of forming the organic functional layer using the coating apparatus according to any one of the first to sixth inventions. Including.

  According to the present invention, an air flow generator is arranged in the vicinity of the nozzle, and the air flow is generated during or immediately after application, whereby the solvent atmosphere can be made uniform, so that the evaporation rate of the solvent component contained in the ink can be made uniform. As a result, the film thickness uniformity of the organic EL layer formed in the pixel formation region can be improved.

  Further, in the second invention, since the airflow can be reduced by generating the airflow from the first and second airflow generation units, the uniformity of the film thickness of the organic EL layer formed in the pixel formation region is reduced. Can be improved.

  In the third aspect of the invention, since the airflow generation unit is arranged so as to sandwich the plurality of nozzles and the airflow is generated, the airflow unevenness in each nozzle can be reduced, so that it is formed in the pixel formation region. The film thickness uniformity of the organic EL layer can be improved.

The external view which shows embodiment of this invention and showed the coating device which concerns on 1st Embodiment 1 illustrates an embodiment of the present invention and is a cross-sectional view in the vicinity of a nozzle head of a coating apparatus according to a first embodiment. FIG. 3 is a diagram illustrating an embodiment of the present invention, and is an explanatory diagram immediately after ink is poured into a partition wall from a nozzle head. Sectional drawing of the pixel formation area which showed embodiment of this invention and showed that the shape of the coating film was biased Sectional drawing of the pixel formation area which shows embodiment of this invention and showed that there is no deviation of the shape of a coating film FIG. 1, showing an embodiment of the present invention, is an overview diagram showing different configurations of the coating apparatus according to the first embodiment. Sectional drawing which shows embodiment of this invention and shows the nozzle head vicinity of the coating device which concerns on 2nd Embodiment Sectional drawing which shows embodiment of this invention and shows the nozzle head vicinity of the coating device which concerns on 3rd Embodiment 1 is a sectional view of an organic EL element according to an embodiment of the present invention.

  Hereinafter, a coating apparatus according to an embodiment of the present invention, a coating method using the coating apparatus, and a method for manufacturing an organic functional element using the coating apparatus will be described with reference to the drawings. In this embodiment, a display device including a display pixel having a light emitting element such as an organic EL element will be described as an example of the organic functional element.

[First Embodiment]
The configuration and operation of the coating apparatus according to the first embodiment will be described with reference to FIGS.
<Configuration of coating apparatus>
Hereinafter, the configuration of the coating apparatus 10 according to the present embodiment will be described. FIG. 1 is a diagram showing an overall configuration of a manufacturing apparatus according to this embodiment. FIG. 2 is a cross-sectional view in the Y direction in the vicinity of the nozzle head 11 shown in FIG. 1, and shows the relative positional relationship among the nozzle head 11, the airflow generation unit 16, and the substrate 30 according to the present embodiment.

  As shown in FIG. 1, the coating apparatus 10 of the present embodiment includes a nozzle head 11 that applies ink 20 to a substrate 30. The nozzle head 11 corresponds to a nozzle according to the present invention. As shown in FIG. 2, the nozzle head 11 is provided with a nozzle 11a for discharging the ink 20 downward on the lower surface. An ink bottle 12 communicates with the nozzle head 11 via a pipe. Ink is stored in the ink bottle 12. By feeding gas into the ink bottle 12, the ink 20 is pushed out and supplied to the nozzle head 11. Further, a flow control valve 13 and a flow meter 14 are provided in the piping between the ink bottle 12 and the nozzle head 11. The flow meter 14 measures the flow rate of the ink 20 flowing through the pipe. The flow control valve 13 controls the valve so that the flow rate of the ink 20 is constant according to the measurement result of the flow meter 14. By controlling this valve, the coating apparatus 10 controls the flow rate of the ink 20 ejected from the nozzle 11a to be constant.

  Furthermore, the coating apparatus 10 includes a holding unit 15 that supports the nozzle head 11. The holding unit 15 extends in the main scanning direction (X direction in FIG. 1) in which pixels of the same color are arranged, and supports the nozzle head 11 so as to be movable. The holding unit 15 is provided with an air flow generation unit 16, and the air flow 16 a is generated by feeding gas into the air flow generation unit 16.

  The nozzle 11a of the nozzle head 11 and the opening 16b of the airflow generation unit 16 are directed downward, and the substrate 30 is disposed facing the nozzle 11a. A movable mechanism is disposed on the movable stage 17 (not shown). The moving mechanism enables the movable stage 17 and the nozzle head 11, and thus the nozzle 11 a, to move relative to the surface direction of the substrate 30. With this moving mechanism, the substrate 30 can move in the sub-scanning direction (Y direction) relative to the main scanning direction (X direction), which is the moving direction of the nozzle head 11. Note that the X direction and the Y direction shown in FIG. 1 are orthogonal to each other in a plan view, and can be applied to a desired position by moving relative to each other.

  Hereinafter, the details of the nozzle head 11 and the airflow generation unit 16 will be described with reference to FIG. As shown in FIG. 2, the nozzle head 11 includes a nozzle 11a and a nozzle fixing portion 11b. The appearance of the nozzle fixing portion 11b is, for example, a cylindrical shape, and the inside is a cavity. A nozzle 11a is fixedly arranged at the bottom in the cavity. The nozzle fixing portion 11b is generally a metal member, and is made of, for example, SUS. However, any material may be used as long as it has solvent resistance.

  The cavity in which the nozzle 11a is fixed is filled with ink 20 through a pipe. Here, the nozzle 11a is formed by a minute hole having a diameter of about 3 μm to 20 μm, and the ink 20 is ejected from the nozzle 11a to the substrate in a liquid column state in the coating process. Any material can be used for the nozzle 11a as long as it has solvent resistance. However, a material that can accurately process the hole is desirable, and it is resistant to deformation caused by pressurization, for example, a metal material. It is desirable that

  The airflow generation unit 16 provided in the holding unit 15 that supports the nozzle head 11 has an opening 16b extending in the main scanning direction (X direction), and the gas sent from the pipe passes through the opening 16b. Thus, the air flow 16a is generated. As the shape of the opening 16b, for example, a slit shape that is longer than the length of the substrate 30 in the X direction and extends (extends) in the main scanning direction (X direction) can be used. The air flow generation unit 16 and the opening 16b are arranged so that the longitudinal direction of the slit shape is along the main scanning direction (X direction) that is the moving direction of the nozzle head 11, and in the sub scanning direction (Y direction), the nozzle It is disposed close to the head 11 and applied in advance (that is, in the (+ Y) direction in FIG. 1). Note that any material may be used as the material of the airflow generation unit 16 as long as it has solvent resistance. Here, the air flow 16 is preferably a rare gas such as helium, neon, or argon, or an inert gas such as nitrogen in view of the influence on the organic EL material.

<Operation of coating device>
Hereinafter, the operation of the coating apparatus 10 according to the present embodiment will be described.
First, as shown in FIG. 1, the ink filled in the ink bottle 12 is supplied to the nozzle head 11 via a pipe. When supplying the ink 20 to the nozzle head 11, the inside of the ink bottle 12 is pressurized with a gas, and the ink 20 is pushed out of the ink bottle 12, whereby the ink can be supplied to the nozzle head 11. Between the ink bottle 12 and the nozzle head 11, a flow rate control valve 13 for controlling the amount of ink discharged and a flow meter 14 for measuring the flow rate of ink supplied to the nozzle head 11 are arranged. Therefore, the flow control valve 13 can be adjusted based on information from the flow meter 14 (that is, ink flow rate). In this way, since the ink flow rate can be adjusted, a stable desired ink flow rate can be obtained.

  Next, the ink 20 supplied from the ejection port of the nozzle head 11 is ejected, and the movable stage 17 is moved in the (+ Y) direction or the (−Y) direction, so that the ink is continuously arranged on the movable stage 17. The coating film 21 is formed on the substrate 30. For example, the substrate 30 having a stripe-shaped pixel formation region parallel to the X direction is disposed on the movable stage 17, and the movable stage 17 and the nozzle head 11 are relatively moved in the X direction. At this time, the movement of the movable stage 17 and the nozzle head 11 is synchronized by the positional information of the movable stage 17 and the nozzle head 11, and the like, and stripe-shaped R (Red), G (Green), or B (Blue) pixels. The ink 20 is continuously applied to the formation region to form a coating film 21 to be a pixel. Then, after the coating film 21 is formed in one stripe-shaped R, G, or B pixel formation region, the movable stage 17 and the nozzle head 11 are relatively moved in the Y direction to apply the coating to the next pixel formation region. A film 21 is formed.

  At this time, as shown in FIG. 2, by generating the air flow 16a from the air flow generation unit 16, the difference in the solvent atmosphere during application can be reduced, so that the evaporation rate of the solvent contained in the ink 20 becomes uniform and pixel formation is performed. The film thickness of the organic EL layer formed in the region is also made uniform. Hereinafter, this effect will be described with reference to FIGS.

  As shown in FIG. 3, the ink 20 ejected from the nozzle head 11 is poured into the partition wall 31 and then dried and solidified to form the coating film 21. In this drying, since the movable stage 17 and the nozzle head 11 are relatively moved to apply the ink 20 continuously to the pixel formation region, the solvent of the ink 20 on the side to be applied (the (+ Y) direction side). The concentration of the component is relatively higher than the concentration of the solvent component of the ink 20 on the side ((−Y) direction side) to be applied later. Therefore, the drying speed of the solvent contained in the ink is faster on the side to be applied later ((−Y) direction side) than on the side to be applied in advance ((+ Y) direction side). This non-uniform local drying speed of the ink 20 in the sub-scanning direction (Y direction) affects the film shape of the organic EL layer formed in the pixel formation region. As shown in FIG. On the side of the partition wall 31 on the (+ Y) direction side), the film surface greatly approaches the wall surface, and on the other side (the (−Y) direction side) partition wall 31, the upward movement to the wall surface is suppressed so The shape is greatly biased.

  On the other hand, in the coating apparatus 10 according to the present embodiment, as shown in FIGS. 1 and 2, the airflow generation unit disposed on the side ((+ Y) direction side) that is adjacent to the nozzle head 11 and applied in advance. The solvent component of the ink 20 is diffused by the air flow 16a from the nozzle 16, and the concentration of the solvent component is made uniform. Therefore, as shown in FIG. 5, it is possible to produce the coating film 21 b with no unevenness in the shape of the film cross section. Further, since the opening 16b of the airflow generation unit 16 has a slit shape extending in the main scanning direction (X direction), a sheet-like airflow 16a can be generated and applied to the pixel formation region in advance ( The solvent component from the (+ Y) direction side) can be blocked, and the evaporation rate can be made uniform without being affected by the concentration of the solvent component of the ink.

  The ink 20 ejected from the nozzle head 11 is preferably continuously ejected in consideration of nozzle clogging and flight bending due to ink drying. For this reason, the coating film 21 is formed in a region other than the pixel formation region. However, the coating film 21 is appropriately covered by covering the outside of the film formation region with a masking member or removing the coating film after film formation. Can leave. As described above, the coating apparatus 10 according to the present embodiment can reduce film thickness unevenness due to non-uniformity in the evaporation rate of the solvent during or immediately after coating.

  In the present embodiment, the substrate 30 having the stripe-shaped pixel formation region has been described. However, the present invention is not limited to this, and the pixel formation region may have a lattice shape. Moreover, although the case where the nozzle head 11 and the nozzle 11a were one was demonstrated, multiple may be sufficient.

  In the present embodiment, the airflow generator 15 is fixed at a fixed position regardless of the movement of the coating apparatus 10 in which the airflow generator 16 is provided in the holding unit 15, that is, the movable stage 17 and the nozzle head 11 (and hence the nozzle 11 a). The coating apparatus 10 generates airflow. However, as shown in FIG. 6, the airflow generation unit 16 is provided in the nozzle head 11, and the airflow generation unit 16 is also linked to the movement of the nozzle head 11 in the main scanning direction (X direction) which is the movement direction. Similarly, with the configuration of the coating apparatus 10 that moves in the main scanning direction (X direction), the evaporation rate can be made uniform by the same operation as described above.

[Second Embodiment]
The coating apparatus 10 according to the second embodiment will be described below. The coating apparatus 10 according to the second embodiment and the coating apparatus 10 according to the first embodiment described above have substantially the same configuration, but the relative relationship among the nozzle head 11, the airflow generation unit 16, and the substrate 30. The positional relationship is different. For this reason, only the relative positional relationship among the nozzle head 11, the airflow generation unit 16, and the substrate 30 will be described with reference to FIG.

  In the coating apparatus 10 according to the first embodiment, the airflow generation unit 16 is disposed only on the side ((+ Y) direction side) that is adjacent to the nozzle head 11 and is applied in advance. In this case, in the sub-scanning direction (Y direction), since the air flow 16a is from one side, the shape of the film cross section may be largely biased by the air flow 16a from the air flow generation unit 16. Therefore, as shown in FIG. 7, airflow is generated on both sides of the side to be applied in advance ((+ Y) direction side) and the side to be applied later ((−Y) direction side) close to the nozzle head 11. The generator 16 is arranged to generate an air flow 16a. Thereby, the deviation of the air flow 16a in the sub-scanning direction (Y direction) is eliminated, and the deviation of the film cross-sectional shape is also eliminated. In this case, it is desirable to arrange the airflow generation parts 16 so as to sandwich the nozzle head 11 and to arrange them substantially parallel to each other.

  Moreover, although the case where the nozzle head 11 and the nozzle 11a were one was demonstrated, multiple may be sufficient. In this case, the airflow generation sections 16 on both sides of the side to be applied in advance (the (+ Y) direction side) and the side to be applied later (the (−Y) direction side) form pixels discharged from a plurality of nozzles. Oppositely arranged on both outer sides of the region.

[Third Embodiment]
The coating apparatus 10 according to the second embodiment has a plurality of nozzle heads 11 and includes a side to be applied in advance ((+ Y) direction side) and a side to be applied later ((−Y) direction side). When the airflow generation units 16 are arranged on both sides, the airflow 16a is distributed to each of the plurality of nozzle heads 11, so that the shape of the film cross section may be largely biased by the airflow 16a from the airflow generation unit 16. Therefore, as shown in FIG. 8, the airflow generation units 16 are arranged so as to face the plurality of nozzle heads 11 (two in the figure) so as to sandwich the individual nozzle heads 11, and further, the airflow generation units 16 are arranged substantially parallel to each other. . Thereby, the deviation of the air flow 16a with respect to each nozzle head 11 is eliminated, and the deviation of the film cross-sectional shape is also eliminated.

<Production of organic EL element>
Hereinafter, the pattern forming body of the hole injection layer 33, the hole transport layer 34, and the organic light emitting layer 35 included in the organic EL element (organic functional element) is collectively referred to as an organic functional layer. The case where it forms using the coating device 10 which concerns on embodiment is demonstrated referring FIG.

(Preparation of substrate)
As the board | substrate 30 which concerns on this invention, the board | substrate which has insulation, such as glass and a plastic film, can be used, for example. In particular, in the case of a bottom emission type in which light emission is extracted from the substrate side, a light-transmitting material is used as the material of the substrate. As a material of the light-transmitting base material, it is sufficient that at least a pixel electrode layer 32 described later is formed on a plastic film such as glass, quartz, polyethersulfone, or polycarbonate. In the case of forming an active matrix organic EL element, the substrate 30 may be a driving substrate on which a thin film transistor (TFT) is formed, and a known thin film transistor may be used as the thin film transistor to be used. Specifically, a thin film transistor mainly including an active layer in which a source / drain region and a channel region are formed, a gate insulating film, and a gate electrode can be given. The structure of the thin film transistor is not particularly limited, and examples thereof include a staggered type, an inverted staggered type, a bottom gate type, a top gate type, and a coplanar type. As a material of the semiconductor layer of the thin film transistor, materials such as polythiophene, polyaniline, copper phthalocyanine, and perylene derivatives may be used, and amorphous silicon, polysilicon, and metal oxide may be used. Further, a color filter layer, a light scattering layer, a light polarizing layer, or the like may be provided on either side of the substrate.

(Production of pixel electrode)
A pixel electrode 32 patterned as an anode is provided on the substrate 30. As the material of the pixel electrode 32, 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, it is preferable to use ITO because of its low resistance, solvent resistance, and transparency.
The pixel electrode 32 is formed by a dry film formation method 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, or a wet film formation method such as a gravure printing method or a screen printing method. The pixel electrode 32 is formed in the light emitting pixel region by being formed into a desired pattern by a photolithography method or the like.

(Production of partition walls)
After the pixel electrode 32 is formed, the partition wall 31 is formed by a photolithography method or the like using a photosensitive material between the adjacent pixel electrodes 32. A matrix or stripe-shaped partition wall 31 is provided on the substrate 30, and a region surrounded by the partition wall 31 is a discharge region in which a film of the coating ink 21 is formed.

  The photosensitive material for forming the partition wall 31 may be either a positive type resist or a negative type resist, and may be a commercially available one, but it needs to have insulating properties. When the partition wall 31 does not have sufficient insulation, a current flows to the adjacent pixel electrode 32 through the partition wall 31 and a display defect occurs. Also, proper display may not be possible due to TFT malfunction. Specific examples of the photosensitive material include, but are not limited to, polyimide, acrylic resin, novolac resin, and fluorene. Further, for the purpose of improving the display quality of the organic EL display, a light shielding material may be included in the photosensitive material. Further, if necessary, a water repellent can be added, or plasma or UV can be irradiated to impart liquid repellency to the ink 20 after formation.

  The photosensitive resin forming the partition wall 31 is applied using a known coating method such as a spin coater, bar coater, roll coater, die coater, or gravure coater. Next, in the step of forming a pattern of the partition wall 31 by pattern exposure and development, the pattern of the partition wall 31 can be formed by a conventionally known exposure and development method. Regarding firing, firing can be performed by a conventionally known method using an oven, a hot plate or the like.

  The partition wall 31 preferably has a thickness in the range of 0.5 μm to 5.0 μm. This can prevent color mixing with adjacent pixels when performing separate coating for each pixel using an organic light emitting ink in which organic light emitting materials having different luminescent colors are dissolved or dispersed in a solvent. It should be noted that if the partition wall 31 is too low, the effect of preventing leakage current between adjacent pixels, preventing short-circuiting, and preventing color mixing of organic light-emitting inks may not be obtained.

(Production of functional layer)
Subsequently, the organic functional layer includes an organic light emitting layer 35 that emits light upon application of a voltage. The organic light-emitting layer 35 may be constituted by a single layer, or in addition to the organic light-emitting layer 35, the light-emitting auxiliary layer for improving the light emission efficiency may be laminated. good. Examples of the light emission auxiliary layer include a hole transport layer 34, a hole injection layer 33, an electron transport layer (not shown), an electron injection layer (not shown), and the like.

(Adjustment of hole injection layer ink)
The adjustment of the ink for forming the hole injection layer 33 will be described. The resistance of the formed hole injection layer 33 is preferably 1 × 10 ⁶ Ω · cm or less from the viewpoint of luminous efficiency. Examples of hole injection materials include metal phthalocyanines such as copper phthalocyanine and tetra (t-butyl) copper phthalocyanine, and metal-free phthalocyanines, quinacridone compounds, 1,1-bis (4-di-p-tolylaminophenyl) Cyclohexane, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine, N, N′-di (1-naphthyl) -N, Aromatic amine low molecular hole injection and transport materials such as N′-diphenyl-1,1′-biphenyl-4,4′-diamine, polyaniline, polythiophene, polyvinylcarbazole, poly (3,4-ethylenedioxythiophene) ) And polystyrene sulfonic acid and other polymer hole transport materials, polythiophene oligomer materials, and other existing hole injection materials Door can be.

  Examples of the solvent for dissolving or dispersing the hole injection material include halogen solvents such as chloroform, dichloromethane, dichloroethane, trichloroethylene, ethylene dichloride, tetrachloroethane, chlorobenzene, N-methyl-2-pyrrolidone (NMP), dimethyl Polarity of aprotic polar solvents such as formamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), alkoxy alcohols such as propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, etc. The solvent is raised.

(Preparation of hole transport layer ink)
The ink adjustment for forming the hole transport layer 34 will be described. Examples of the hole transporting substance include poly (N-vinylcarbazole) (hereinafter also referred to as PVK), poly (para-phenylene vinylene), carbazole biphenyl (hereinafter also referred to as CBP), N, N′—. Diphenyl-N, N′-bis (1-naphthyl) -1,1′-biphenyl-4,4′-diamine (hereinafter also referred to as NPD), N, N′-diphenyl-N, N′-bis ( 3-methylphenyl) -1,1'-biphenyl-4,4'-diamine (hereinafter also referred to as TPD), 4,4'-bis (10-phenothiazinyl) biphenyl, 2,4,6-triphenyl Examples include -1,3,5-triazole, polyfluorene derivatives, and a copolymer of triphenylamine and fluorene. Examples of the solvent for the functional ink that forms the hole transport layer 34 include cyclone, tetralin, cumene, decalin, durene, cyclohexylbenzene, dihexylbenzene, tetramethylbenzene, and dibutylbenzene.

(Preparation of organic light emitting layer ink)
The ink adjustment for forming the organic light emitting layer 35 will be described. The organic light emitting layer 35 is a layer that emits light by passing an electric current, and the organic light emitting material forming the organic light emitting layer 35 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, polymethylmethacrylate, polyvinylcarbazole, etc. And polyarylene-based, polyarylene vinylene-based, and polyfluorene-based polymer materials. Examples of the solvent of the functional ink that forms the organic light emitting layer 35 include siemen, tetralin, cumene, decalin, durene, cyclohexylbenzene, dihexylbenzene, tetramethylbenzene, and dibutylbenzene.

(Formation of hole injection layer)
A functional ink containing a hole injection material is ejected to the substrate 30 on which the partition wall 31 baked as described above is formed by using the coating apparatus 10 described above to form the hole injection layer 33.
(Formation of hole transport layer)
After the hole injection layer 33 is formed, the hole transport layer 34 is formed by discharging functional ink containing a hole transport material using the coating apparatus 10 described above. The hole transport layer 34 is a layer for flowing holes injected from the hole injection layer 33 to the organic light emitting layer 35, and is made of a hole transport material.
(Formation of organic light emitting layer)
After the formation of the hole transport layer 34, the organic light emitting layer 35 is formed by discharging functional ink containing an organic light emitting material using the coating apparatus 10 described above.

(Formation of cathode layer)
After the organic light emitting layer 35 is formed, the cathode layer 36 is formed in a pattern corresponding to the pattern of the pixel electrode 32. As the material of the cathode layer 36, a material corresponding to the light emission characteristics of the organic light emitting layer 35 can be used. For example, a simple metal such as lithium, magnesium, calcium, ytterbium, and aluminum or a stable metal such as gold and silver can be used. And alloys thereof. Alternatively, a conductive oxide such as indium, zinc, or tin can be used. As a method of forming the cathode layer 36, a method of forming by a vacuum vapor deposition method using a mask may be mentioned.

  An organic EL display panel can be obtained by hermetically sealing the organic EL element constituted by these using a glass cap 38 and an adhesive 39 together with a desiccant 37 in order to protect them from external oxygen and moisture. . The sealing method is not limited to this configuration, and any method may be used as long as it can be protected from external oxygen and moisture.

  In the organic EL element, a configuration in which the hole injection layer 33, the hole transport layer 34, and the organic light emitting layer 35 are stacked from the pixel electrode side between the pixel electrode 32 serving as the anode and the cathode layer 36 has been described. However, the organic EL element according to the present embodiment is not limited to this. For example, a layered structure in which layers such as a hole blocking layer, an electron transporting layer, and an electron injecting layer other than the hole transporting layer 34 and the organic light emitting layer 35 are selected between the pixel electrode 32 and the cathode layer 36 as necessary. Can do. Moreover, when forming these layers, the formation method similar to the organic light emitting layer 35 can be used.

  In this embodiment, the hole injection layer 33, the hole transport layer 34, and the organic light emitting layer 35 are produced using the coating apparatus 10, but it is not necessary to use the coating apparatus 10 for all layers. Can also be used as appropriate. Moreover, in this embodiment, although the organic EL element is manufactured using the coating device 10, the said coating device does not limit an object to an organic EL element. It can be suitably used as an element constituting other display devices such as a color filter and a thin film transistor.

[Example]
Next, examples of the present invention will be described.
An ITO (indium-tin oxide) thin film is formed on a 3-inch diagonal glass substrate 30 by sputtering, and the ITO film is patterned by photolithography and etching with an acid solution to form pixel electrodes 32. Formed. The line pattern of the pixel electrode 32 is a pattern in which a line width is 70 μm, a space is 60 μm, and a line is formed in about 590 × 159 in an about 7.6 mm square.

  Next, an insulating layer was formed as follows. First, a polyimide resist material was spin-coated on the entire surface of the glass substrate 30 on which the pixel electrode 32 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 was 2.5 μm. A partition wall 31 which is an insulating layer having a stripe pattern is formed between the pixel electrodes 32 by a photolithography method on the photoresist material applied to the entire surface. The partition wall 31 has ink repellency.

  Next, as a hole injection ink, a mixture of polymer hole injection materials such as poly (p-phenylene vinylene) and polyaniline is prepared using propylene glycol monobutyl ether, and the ink has a solid content concentration of 3.0% and a viscosity. An ink of 25 mPa · s was prepared. The produced hole injection ink was put in the ink bottle 12. The hole injection ink in the ink bottle 12 was supplied to the nozzle head 11 through the ink supply tube by pressurizing the ink bottle 12. Between the ink bottle 12 and the nozzle head 11, a flow rate control valve 13 for controlling the amount of ink 20 to be ejected and a flow meter 14 for measuring the flow rate of the ink flowing to the nozzle head 11 are provided. Based on the information of the flow meter 14, the flow rate is adjusted by feeding back to the flow rate control valve 13, thereby obtaining a stable desired flow rate of the hole injection ink.

  The glass substrate 30 having the stripe pattern partition wall 31 imparted with the ink repellency was fixed to the movable stage 17. Further, the movable stage 17 can move in the (+ Y) or (−Y) direction. The nozzle head 11 can move in the (+ X) or (−X) direction perpendicular to the (+ Y) or (−Y) direction. By moving the movable stage 17 and the nozzle head 11 relatively, it is possible to continuously form the coating film 21 serving as a pixel in the pixel formation region of the glass substrate 30 on the movable stage 17.

  The hole injection ink is filled in a rectangular parallelepiped nozzle head 11 made of stainless steel from an ink supply tube. The inside of the nozzle head 11 is a manifold, and can be discharged in the vertical direction with respect to the glass substrate 30 from the nozzle 11a made of a metal material having a small hole with a diameter of 10 μm.

  The movable stage 17 and the nozzle head 11 moved relative to each other at 1 m / second, and hole injection ink was continuously discharged at 100 μl / second to the pixel formation region of the glass substrate 30 on the movable stage 17. The air flow 16a was generated from the air flow generation part 16 disposed on the side (the (+ Y) direction side) that was applied to the nozzle head 11 before and after the application from the hole injection ink to after the application. Thereafter, the hole injection layer 33 was formed by placing it on a hot plate at 200 ° C. for 30 minutes. Thereafter, it was confirmed that the hole injection layer 33 having a desired film thickness was obtained by measuring the film thickness.

  Next, a hole transport material composed of a polyfluorene derivative was prepared using cyclohexylbenzene to prepare an ink having an ink solid content concentration of 4.0% and a viscosity of 20 mPa · s. When the hole transport layer 34 is formed, the hole transport material is discharged onto the glass substrate 30 on which the hole injection layer 33 is formed by the same apparatus and procedure as the hole injection layer 33 is formed. did. After discharging, it was confirmed that the hole transport layer 34 was formed by baking at 200 ° C. for 1 hour in a nitrogen atmosphere to obtain a hole transport layer 34 having a desired film thickness.

  Next, red, green, and blue organic light emitting materials made of poly (paraphenylene vinylene) derivatives are prepared using cyclohexylbenzene, and the ink has a solid concentration of 7.0% and a viscosity of 30 mPa · s. A green ink having a partial concentration of 5.0% and a viscosity of 25 mPa · s, and red, green and blue inks having a solid concentration of 6.0% and a viscosity of 20 mPa · s were prepared. When forming the organic light emitting layer 35, the organic light emitting material is discharged onto the glass substrate 30 on which the hole transport layer 34 has been formed by the same apparatus and procedure as those for forming the hole injection layer 33 described above to form a film. did. After discharge film formation, the organic light emitting layer 35 of red, green, and blue was formed by baking at 130 ° C. for 30 minutes in a nitrogen atmosphere. Thereafter, it was confirmed that the organic light emitting layer 35 having a desired film thickness was obtained by measuring the film thickness.

  A cathode layer 36 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 32. Finally, in order to protect these organic EL constituents from external oxygen and moisture, a glass cap 38 and an adhesive 39 together with a desiccant 37 were hermetically sealed to produce an organic EL display panel. In the periphery of the display portion of the organic EL element substrate obtained in this way, there are an extraction electrode on the anode side connected to each pixel electrode 32 and an extraction electrode on the cathode side, and these are connected to the power source. The lighting display of the obtained organic EL element substrate was confirmed, and the light emission state was checked.

  As described above, since the air flow generation unit 16 is installed in the vicinity of the nozzle head 11 and the air flow 11a is generated, the difference in the solvent atmosphere during the application can be reduced in the vicinity of the coated film. The evaporation rate of the contained solvent became uniform, and the unevenness of the film cross-sectional shape of the coating film 21b of the organic EL layer formed in the pixel formation region could be suppressed. Therefore, an organic EL element substrate free from uneven luminance was obtained.

[Comparative example]
Unlike the coating apparatus 10 according to the present embodiment, when the airflow generation unit 16 is not provided, the evaporation rate of the solvent contained in the ink 20 becomes nonuniform during the coating process, and the film cross section of the coating film 21a of the organic EL layer The shape was biased and uneven light emission occurred.

  The present invention is applicable to displays such as televisions, tablets, portable terminals, and personal computers.

DESCRIPTION OF SYMBOLS 10 ... Coating apparatus 11 ... Nozzle head 11a ... Nozzle 11b ... Nozzle fixing part 12 ... Ink bottle 13 ... Liquid quantity control valve 14 ... Flow meter 15 ... Holding part 16 ... Airflow generation part 16a ... Airflow 16b ... Opening part 17 ... Movable stage 20 ... Ink 21 ... Coating 21a ... Coating 21b ... Coating 30 ... Substrate 31 ... Partition 32 ... Pixel electrode 33 ... Hole injection layer 34 ... Hole transport layer 35 ... Organic light emitting layer 36 ... Cathode layer 37 ... Desiccant 38 ... Glass cap 39 ... Adhesive

Claims (10)

A stage on which the substrate is installed;
A nozzle having a discharge port for discharging a coating liquid on the substrate;
A moving mechanism capable of relatively moving the stage and the nozzle in the surface direction of the substrate,
Provided with an airflow generation unit that generates an airflow in the vicinity of the nozzle,
The said airflow generation part has an opening part extended | stretched in the moving direction of the said nozzle, and generates the sheet-like airflow in the vicinity of the said nozzle from the said opening part, The coating device characterized by the above-mentioned. The air flow generation unit includes a first air flow generation unit and a second air flow generation unit,
2. The coating apparatus according to claim 1, wherein the first air flow generation unit and the second air flow generation unit are disposed to face each other substantially in parallel with an area discharged by the nozzle. A plurality of the nozzles and the airflow generation unit, respectively,
The coating apparatus according to claim 1, wherein the air flow generation units are arranged to face each other substantially in parallel with the nozzles interposed therebetween.   4. The air flow generation unit according to claim 1, wherein the air flow generation unit is provided in a holding unit that supports a nozzle head, and generates the air flow at a fixed position regardless of movement of the stage and the nozzle. 2. The coating apparatus according to item 1.   4. The coating apparatus according to claim 1, wherein the air flow generation unit is provided in a nozzle holding unit, and the air flow generation unit moves in conjunction with movement of the nozzle. 5.   The coating apparatus according to claim 1, wherein the air flow is an inert gas. A stage on which the substrate is installed;
A nozzle having a discharge port for discharging a coating liquid on the substrate;
A coating method that coats and forms the coating liquid on the substrate using a coating device that includes a moving mechanism that allows the stage and the nozzle to move relatively in the surface direction of the substrate. And
A step of forming a coating film by discharging the coating liquid from the nozzle;
Generating a sheet-like air current extending in the nozzle moving direction in the vicinity of the nozzle.   The coating method according to claim 7, further comprising a step of generating a first air flow and a second air flow that are opposed to each other with an area discharged by the nozzle interposed therebetween. A step of forming a coating film by discharging the coating liquid from a plurality of the nozzles;
The method according to claim 7, further comprising: generating a plurality of airflows facing each other across the plurality of nozzles. A method for producing an organic functional element having a plurality of organic functional layers,
The manufacturing method of the organic functional element characterized by including the process of forming the said organic functional layer using the coating device of any one of Claim 1-6.