JP2015207527A - Method of forming functional layer of organic light emission device and method of manufacturing organic light emission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a functional layer forming method for an organic light emission device in which when a functional layer is formed in each groove space by a wet method with respect to a bank-appended substrate having plural first banks formed to extend in one direction along the surface of a base substrate and plural second banks formed in respective groove spaces comparted by the first banks, occurrence of dispersion in film thickness of the functional layer between pixel areas can be suppressed.SOLUTION: In a process of forming a hole transport layer or a hole injection and transport layer 116, ink is jetted from a first nozzle head 221 to each groove space 125 while a head unit 220 having the first nozzle head 221 and a second nozzle head 222 is scanned in an X direction, and the second nozzle head 222 jets ink while passing above the groove space 125. The first nozzle head 221 selectively coats ink on the second bank 114 in each groove space 125, and the second nozzle head 222 coats ink in the whole of each groove space 125.

Description

  The present invention relates to a forming method for forming a functional layer in an organic light emitting device, and more particularly to a method for forming a functional layer by applying ink to a region partitioned by a bank.

In recent years, an organic EL device in which a plurality of organic EL elements are arranged in a matrix on a substrate has been put to practical use as a light-emitting display device. This organic EL device has high visibility because each organic EL element emits light, and is excellent in impact resistance because it is a complete solid element.
In the organic EL device, each organic EL element has a basic structure in which a light emitting layer containing an organic light emitting material is disposed between a pair of electrodes of an anode and a cathode, and a voltage is applied between the pair of electrodes during driving. Is applied, and light is emitted along with recombination of holes injected from the anode into the light emitting layer and electrons injected from the cathode into the light emitting layer. In an organic EL device for full-color display, such an organic EL element forms RGB subpixels, and adjacent RGB subpixels are combined to form one pixel.

  In an organic EL device, the light emitting layer of each organic EL element and the light emitting layer of an adjacent organic EL element are generally partitioned by a bank made of an insulating material. Further, an organic layer such as a hole injection layer, a hole transport layer, or a hole injection / transport layer is interposed between the anode and the light emitting layer as necessary, and also between the cathode and the light emitting layer as necessary. An electron injection layer, an electron transport layer, or an electron injection / transport layer is interposed. These organic layers, hole injection layers, hole transport layers, hole injection / transport layers, electron injection layers, electron transport layers, electron injection / transport layers, and the like are collectively referred to as functional layers.

  When manufacturing such an organic EL device, a striped bank (so-called “line bank”) extending in one direction is formed on a substrate, and a functional layer is formed in a groove space defined by the line bank. There is a process to do. For forming the functional layer, a wet method is often used in which ink for forming a light emitting layer containing a high molecular material or a low molecule having good thin film formability is applied to the groove space by an inkjet method or the like. According to this wet method, an organic layer and a light emitting layer can be formed relatively easily even in a large panel.

Like the image display device disclosed in Patent Document 1, in addition to the line bank (first bank), the second bank having a height lower than the first bank in the direction orthogonal to the first bank is provided on the substrate. In some cases, adjacent pixel regions are partitioned by forming.
In this way, the functional layer forming ink is continuously applied to the entire groove space between the first banks on the substrate in which the first bank and the second bank are formed, thereby forming the groove space. It is possible to form a functional layer with relatively little thickness unevenness in the direction in which the film extends.

JP 2007-234232 A

However, even if ink is continuously applied to the entire groove space partitioned by the first bank as described above to form a functional layer, the thickness of the functional layer may vary between pixels. Thus, when the film thickness of the functional layer varies between the pixel regions, the light emission characteristics between the pixels are different, and the image quality is deteriorated.
The present invention has been made in view of the above-described problems, and includes a base substrate, a plurality of first banks having a strip shape in plan view extending in one direction along the surface of the base substrate, and a plurality of first banks. A functional layer of an organic light-emitting device is formed in each groove space by a wet method with respect to a banked substrate having a plurality of second banks formed at intervals in one direction in each groove space partitioned by one bank. It is an object to suppress variation in the thickness of the functional layer between pixel regions when forming.

  In order to achieve the above object, a method for forming a functional layer according to one embodiment of the present invention includes a base substrate, a plurality of first banks extending in a first direction along the surface of the base substrate, and a plurality of banks. A banked substrate having a plurality of second banks spaced apart in the first direction in each groove space defined by the first bank is prepared, and a functional layer of the organic light emitting device is formed in each groove space A head having a first nozzle group composed of a plurality of nozzles distributed along the first direction and a second nozzle group composed of a plurality of nozzles distributed in the first direction. The first nozzle group is used to scan a portion on the plurality of second banks in the groove space of the banked substrate while scanning the portion in the second direction intersecting the first direction along the surface of the base substrate. And applying a first ink containing a functional layer material, Using the nozzle group, the second ink containing the functional layer material is applied to the entire groove space of the banked substrate, and the first ink and the second ink applied to each groove space are dried to function. It was decided to form a layer.

According to the method for forming a functional layer according to the above aspect, as the head unit is scanned in the second direction, the first nozzle group and the second nozzle that are provided in the head unit are provided in each groove space of the banked substrate. After one of the nozzle groups passes, the other nozzle group passes.
During the scanning of the head portion, the first ink is selectively applied to the plurality of second banks in each groove space of the banked substrate using the first nozzle group, and the second ink is used. Using the nozzle group, the second ink containing the functional layer material is applied to the entire groove space of the banked substrate.

Accordingly, since the ink is applied twice by the first nozzle group and the second nozzle group on the second bank in each groove space, an effect of reducing the occurrence of ink non-wetting can be obtained.
As a result, the probability that the ink is not wet in the vicinity of the second bank in each groove space is lowered, so that it is possible to suppress variation in the film thickness of the functional layer between the pixel regions.
Further, according to the method for forming a functional layer in the above embodiment, the ink application to each groove space is performed twice by the scanning of the head portion, so that it is easily performed without any additional work. can do.

1 is a schematic block diagram showing a schematic configuration of an organic EL display device 1 according to an embodiment. 3 is a schematic plan view showing an arrangement form of sub-pixels 11a, 11b, and 11c in the display panel 10. FIG. It is a schematic cross section which shows the structure in the AA cross section of FIG. 3 is a process diagram showing a manufacturing process of the display panel 10. FIG. It is a schematic perspective view of the board | substrate 150 with a bank. 2 is a diagram illustrating a main configuration of an ink application device 200. FIG. (A), (b) is a top view which shows the position which applies an ink application from the 1st nozzle head 221 and the 2nd nozzle head 222 with respect to groove space. (A), (b) is a cross-sectional schematic diagram which shows the mode of the ink application from the 1st nozzle head 221. FIG. (A)-(c) is a cross-sectional schematic diagram which shows the mode of the ink application from the 2nd nozzle head 222. FIG. (A)-(c) is a top view which shows a mode that an ink layer is formed in groove space by the formation method of the hole transport layer or hole injection and transport layer 116 concerning a comparative example and embodiment. It is a figure which shows the ink application | coating method concerning a modification.

[Background to Invention]
As described above, the inventor is partitioned by the base substrate, the plurality of first banks in a plan view strip shape extending in one direction along the surface of the base substrate, and the plurality of first banks. A functional layer formed when forming a functional layer of an organic light emitting device by applying ink to each groove space on a banked substrate having a plurality of second banks formed in each groove space The reason for the variation in the film thickness between the pixels was considered as follows.

  By applying ink to the entire groove space between the first banks, an ink layer is formed so as to cover the second bank, but the second bank protrudes into the groove space. There is a step on the edge of the ink, and it is difficult for ink to be applied to the step. Therefore, in an ink layer formed by applying ink to the groove space, an unwetted region may occur near the edge of the second bank.

In that case, the ink amount between the pixel regions becomes non-uniform, and the film thickness of the formed functional layer is different.
In particular, an ink containing a material for the hole transport layer or the hole injection / transport layer is likely to be repelled on the second bank, so that an unwetted region is likely to occur near the second bank.
As described above, the present inventor has found that one of the causes that the film thickness of the functional layer varies between pixels is that a region where the applied ink is not wetted in a partial region in the groove space is generated. The present inventors have studied a method for eliminating the non-wetting and have arrived at the present invention.

[Aspect of the Invention]
A method for forming a functional layer according to one embodiment of the present invention is defined by a base substrate, a plurality of first banks extending in a first direction along a surface of the base substrate, and a plurality of first banks. A method of preparing a banked substrate having a plurality of second banks formed at intervals in a first direction in each groove space, and forming a functional layer of an organic light emitting device in each groove space, A head unit provided with a first nozzle group mainly composed of a plurality of nozzles distributed along the first direction and a second nozzle group mainly composed of a plurality of nozzles distributed in the first direction; While scanning in the second direction intersecting the first direction along the surface of the base substrate, the first nozzle group is used to selectively function on the plurality of second banks in each groove space of the banked substrate. Apply first ink containing layer material and use second nozzle group The second ink containing the functional layer material is applied to the entire groove space of the banked substrate, and the first ink and the second ink applied to each groove space are dried to form the functional layer. It was.

  According to this functional layer forming method, ink is applied twice on the second bank in each groove space by the first nozzle group and the second nozzle group, thereby reducing the occurrence of ink non-wetting. Effect is obtained. As a result, the probability that the ink is not wet in the vicinity of the second bank in each groove space is lowered, so that it is possible to suppress variation in the film thickness of the functional layer between the pixel regions.

In addition, since the ink application is performed twice for each groove space, the operation can be easily performed without any additional work.
In the method for forming a functional layer of the above aspect, a nozzle head including a first nozzle group and a nozzle head including a second nozzle group may be provided in the head portion with a space therebetween in the second direction.

Alternatively, a plurality of nozzle heads are arranged in the first direction in the head portion, and a first nozzle group is constituted by a part of nozzles provided in each nozzle head, and a second nozzle group is constituted by the remaining nozzles. May be.
Here, in the head portion, the first nozzle group is arranged in front of the second nozzle group in the scanning direction, and the first nozzle group is selectively used on each of the plurality of second banks with respect to each groove space. After applying one ink, a high non-wetting suppression effect can be obtained by applying the second ink to the entirety of each groove space using the second nozzle group.

In addition, when the first ink is applied to each groove space, it is preferable to apply the first ink applied on the second banks adjacent to each other so as not to contact each other.
In the method for forming a functional layer of the above aspect, the following may be performed.
When the second ink is applied to each groove space, the applied second ink is applied so as to be continuous in the first direction.

The first ink and the second ink have the same composition.
The second bank has a lower height from the surface of the base substrate than the first bank.
The second bank has a lower liquid repellency with respect to the first ink than the first bank.
Thereby, the wettability of the 1st ink with respect to a 2nd bank can be improved, and the wettability of the 1st ink on a 2nd bank can be improved.

A method for producing an organic light emitting device according to one aspect of the present invention is a method for producing an organic light emitting device by forming a functional layer on a base substrate, and when forming the functional layer, the functional layer of the above form The forming method is used.
[Embodiment]
Hereinafter, a method for producing a functional layer of the organic EL device according to the embodiment will be described.

First, the overall configuration and manufacturing method of the organic EL device will be described.
1. Configuration of Organic EL Display Device 1 A schematic configuration of the organic EL display device 1 will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, the organic EL display device 1 includes a display panel 10 and a drive / control circuit unit 20 connected thereto. The display panel 10 is a kind of organic light emitting device, and is an organic EL panel using an electroluminescent phenomenon of an organic material.

  As shown in FIG. 2, in the display panel 10, a plurality of subpixels 11a, 11b, and 11c are two-dimensionally arranged in the X direction and the Y direction. In this display panel 10, as an example, the subpixel 11a emits red light (R), the subpixel 11b emits green light (G), and the subpixel 11c emits blue light (B). One pixel (pixel) is constituted by three subpixels 11a, 11b, and 11 adjacent in the X direction.

As shown in FIG. 1, the drive / control circuit unit 20 in the organic EL display device 1 includes four drive circuits 21 to 24 and one control circuit 25.
2 shows an example in which one pixel is configured by combining three subpixels 11a, 11b, and 11c. However, the configuration of the pixel (pixel unit) is not limited to this, and a combination of four or more subpixels is possible. May constitute one pixel.
2. Configuration of Display Panel 10 In the display panel 10, a plurality of subpixels 11a to 11c are two-dimensionally arranged on a substrate (not shown) as shown in FIG. As shown in FIG. 3, each of the subpixels 11 a to 11 c includes a plurality of first banks 115 extending in the Y direction and a plurality of first banks 115 formed at intervals in the Y direction between the first banks 115. It exists in an area (subpixel area) partitioned by two banks 114. In FIG. 5, reference numerals 12a, 12b, and 12c indicate subpixel regions corresponding to the subpixels 11a, 11b, and 11c.

FIG. 3 is a schematic cross-sectional view showing the AA cross section of FIG. 2.
The display panel 10 is based on a TFT substrate 110 in which a TFT layer 101 is formed on a substrate 100. Although not shown in detail, the TFT layer 101 includes three electrodes, a gate, a source, and a drain, a semiconductor layer, a passivation film, and the like.
An interlayer insulating layer 102 is stacked on the TFT substrate 110.

The interlayer insulating layer 102 has a substantially flat upper surface, and subpixels 11a to 11c are formed thereon.
Since the subpixels 11a to 11c have the same basic configuration, the subpixel 11a will be described below as a representative.
The subpixel 11 a includes an anode 103 and a hole injection layer 104 that are sequentially stacked on the interlayer insulating layer 102.

The anode 103 is connected to the upper electrode (electrode connected to the source or drain) of the TFT layer 101 through a contact hole (not shown) provided in the interlayer insulating layer 102.
A first bank 115 is formed on the interlayer insulating layer 102 so as to cover both edges of the hole injection layer 104 in the X direction. Although not shown in FIG. 3, a second bank 114 is formed on the interlayer insulating layer 102 so as to cover both edges of the hole injection layer 104 in the Y direction (see FIG. 8A).

  As shown in FIG. 3, a hole transport layer or hole injection / transport layer 116, an organic light emitting layer 117, and an electron transport layer 118 are stacked between the first banks 115. The hole transport layer or hole injection / transport layer 116, the organic light emitting layer 117, and the electron transport layer 118 are continuously formed in the Y direction, and are not only in the subpixel region but also on the second bank 114. Is also formed.

A cathode 119 and a sealing layer 120 are sequentially formed so as to entirely cover the electron transport layer 118 and the side and top surfaces of the first bank 115.
The sealing layer 120 has a function of suppressing exposure of an organic layer such as the organic light emitting layer 117 to moisture or exposure to air.
A substrate 124 having a black matrix layer 122 and a color filter layer 123 is bonded to the sealing layer 120 with a resin layer 121 interposed therebetween.

The display panel 10 having the above configuration is a top emission type, and emits light in the Z direction as indicated by an arrow in FIG.
3. Constituent material of display panel 10 Substrate 100:
The substrate 100 is, for example, a glass substrate, a quartz substrate, a silicon substrate, molybdenum sulfide, copper, zinc, aluminum, stainless steel, magnesium, iron, nickel, gold, silver or other metal substrate, a gallium arsenide based semiconductor substrate, a plastic substrate, or the like. Etc. are used.

As the plastic substrate, either a thermoplastic resin or a thermosetting resin may be used.
For example, polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), cyclic polyolefin, modified polyolefin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide (PI), Polyamideimide, polycarbonate, poly- (4-methylbenten-1), ionomer, acrylic resin, polymethyl methacrylate, acrylic-styrene copolymer (AS resin), butadiene-styrene copolymer, polio copolymer (EVOH) ), Polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate (PEN), precyclohexane terephthalate (PCT), polyethers, polyether ketones Polyethersulfone (PES), polyetherimide, polyacetal, polyphenylene oxide, modified polyphenylene oxide, polyarylate, aromatic polyester (liquid crystal polymer), polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, styrene, polyolefin Various types of thermoplastic elastomers such as polyvinyl chloride, polyurethane, fluororubber, chlorinated polyethylene, epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester, silicone resin, polyurethane, or these And copolymers, blends, polymer alloys and the like. Moreover, the laminated body which laminated | stacked 1 type or 2 types or more among these can also be used.

Interlayer insulating layer 102:
In the manufacturing process of the display panel 10, an etching process, a baking process, or the like may be performed. Therefore, the interlayer insulating layer 102 is desirably formed of a material that has durability against these processes. The interlayer insulating layer 102 is formed of, for example, an organic compound such as polyimide, polyamide, or acrylic resin.

Anode 103:
Since the display panel 10 is a top emission type, the surface of the anode 103 preferably has high reflectivity. The anode 103 is made of a metal material containing silver (Ag) or aluminum (Al).
The anode 103 can be not only a single layer structure made of a metal material but also a laminate of a metal layer and a transparent conductive layer. Examples of the material for the transparent conductive layer include indium tin oxide (ITO) and indium zinc oxide (IZO).

Hole injection layer 104:
The hole injection layer 104 is formed of, for example, an oxide such as silver (Ag), molybdenum (Mo), chromium (Cr), vanadium (V), tungsten (W), nickel (Ni), iridium (Ir), or PEDOT. It is made of a conductive polymer material such as (mixture of polythiophene and polystyrene sulfonic acid).

Second bank 114:
The second bank 114 is formed of a photosensitive organic material. Specific examples of the organic material include acrylic resins, polyimide resins, siloxane resins, phenol resins, and the like.
However, the material of the second bank 114 is not limited to an organic material, and may be formed of an inorganic insulating material such as SiO2 (silicon oxide), SiN (silicon nitride), or SiON (silicon oxynitride).

First bank 115:
The material of the first bank 115 may be the same as or different from the material of the second bank 114.
The first bank 115 preferably has liquid repellency with respect to the ink for forming the hole transport layer or the hole injection / transport layer 116, the organic light emitting layer 117, and the like by a wet method. Therefore, it is preferable to use a fluorine-based resin as the material of the first bank 115.

As the structure of the first bank 115, not only a single-layer structure but also a multilayer structure of two or more layers can be adopted. In the case of a multilayer structure, the above materials can be used in combination for each layer.
Hole transport layer or hole injection / transport layer 116:
The hole transport layer or the hole injection / transport layer 116 can be formed using, for example, a polymer compound such as polyfluorene or a derivative thereof, or polyarylamine or a derivative thereof.

Organic light emitting layer 117:
Examples of the material of the organic light emitting layer 117 include liparaphenylene vinylene (PPV), polyfluorene, oxinoid compound, perylene compound, coumarin compound, azacoumarin compound, oxazole compound, oxadiazole compound, perinone compound, pyrrolopyrrole compound, naphthalene compound, Anthracene compound, fluorene compound, fluoranthene compound, tetracene compound, pyrene compound, coronene compound, quinolone compound and azaquinolone compound, pyrazoline derivative and pyrazolone derivative, rhodamine compound, chrysene compound, phenanthrene compound, cyclopentadiene compound, stilbene compound, diphenylquinone compound, Styryl compound, butadiene compound, dicyanomethylenepyran compound, dicyanomethylenethiopyran compound, full Resin compounds, pyrylium compounds, thiapyrylium compounds, serenapyrylium compounds, telluropyrylium compounds, aromatic aldadiene compounds, oligophenylene compounds, thioxanthene compounds, cyanine compounds, acridine compounds, metal complexes of 8-hydroxyquinoline compounds, 2-bipyridine compounds Examples thereof include fluorescent substances such as metal complexes, Schiff salts and Group III metal complexes, oxine metal complexes, and rare earth complexes.

Electron transport layer 118:
The electron transport layer 118 is formed of, for example, an oxadiazole derivative (OXD), a triazole derivative (TAZ), a phenanthroline derivative (BCP, Bphen), or the like.
Cathode 119:
Since the display panel 10 is a top emission type, the cathode 119 is formed of a light transmissive material. Specific examples of the material include indium tin oxide (ITO) and indium zinc oxide (IZO).

Sealing layer 120:
The sealing layer 120 is also formed of a light transmissive material.
The material of the sealing layer 120 is, for example, silicon nitride (SiN), silicon oxynitride (SiON), or the like. Further, a sealing resin layer made of a resin material such as an acrylic resin or a silicone resin may be provided on a layer formed of a material such as silicon nitride (SiN) or silicon oxynitride (SiON).

Resin layer 121:
The resin layer 121 is formed from a transparent resin material, for example, an epoxy resin material. However, other than this, a silicone resin or the like can also be used.
Black matrix layer 122:
The black matrix layer 122 is formed of an ultraviolet curable resin material containing a black pigment having excellent light absorption and light shielding properties. Examples of the ultraviolet curable resin include acrylic ultraviolet curable resin materials.

Color filter layer 123:
The color filter layer 123 is formed of a material that selectively transmits visible light in the wavelength range of each color of red (R), green (G), and blue (B), for example, a material based on a known acrylic resin. .
Substrate 124:
The substrate 124 is, for example, a glass substrate, a quartz substrate, a silicon substrate, molybdenum sulfide, copper, zinc, aluminum, stainless steel, magnesium, iron, nickel, gold, silver, or a metal substrate, a gallium arsenide base, like the substrate 100 described above. For example, a semiconductor substrate, a plastic substrate, or the like can be used.

4). Manufacturing Method of Display Panel 10 A manufacturing method of the display panel 10 will be described based on the process diagram of FIG.
In manufacturing the display panel 10, first, a TFT substrate is prepared (step S1). This TFT substrate is obtained by forming the TFT layer 101 on the upper surface of the substrate 100 and is manufactured by a known technique.

Next, an organic material is applied on the TFT substrate to form the interlayer insulating layer 102 (step S2).
The substrate having the interlayer insulating layer 102 thus formed on the TFT substrate is used as a base substrate, and the anode 103 and the hole injection layer 104 are sequentially stacked on the interlayer insulating layer 102 (steps S3 and S4). The anode 103 is formed by, for example, forming a metal film using a sputtering method or a vacuum deposition method and then patterning the metal film using a photolithography method and an etching method.

The hole injection layer 104 is formed, for example, by forming a film made of a metal oxide (for example, tungsten oxide) using a sputtering method and then patterning using a photolithography method and an etching method.
Next, the second bank 114 is formed as follows (step S5).
A bank material (photosensitive photoresist material) for forming the second bank 114 is uniformly applied on the hole injection layer 104. Thereafter, the applied bank material is exposed to light using a patterned mask. Then, a second bank 114 bank pattern is formed by removing uncured excess bank material with a developer.

Next, the first bank 115 is formed as follows (step S6).
A bank material (negative photosensitive resin composition) for forming the first bank 115 is uniformly applied on the second bank 114 on the hole injection layer 1. A mask having an opening corresponding to the pattern of the first bank 115 to be formed is overlaid on the applied bank material layer and exposed from above the mask.

Thereafter, the bank material is patterned by washing out the excess bank material with an alkaline developer to form the bank pattern of the first bank 115.
A UV (ultraviolet) irradiation process and a baking process are performed on the formed second bank 114 and first bank 115 (step S7). The UV irradiation treatment is performed for 150 to 200 seconds, for example. The baking process is performed at a temperature of 150 to 230 ° C. for 10 to 20 minutes, for example.

FIG. 5 is a schematic perspective view of the banked substrate 150 in which the second bank 114 and the first bank 115 are formed on the base substrate including the substrate 100 and the interlayer insulating layer 102.
In the banked substrate 150, a plurality of groove spaces 125 defined by a plurality of first banks 115 are formed in the Y direction on the upper surface side, and each groove space 125 is partitioned by a second bank 114 to form a plurality of grooves. Sub-pixel regions 12 (12a, 12b, 12c) are formed.

  Next, a hole transport layer or a hole injection / transport layer 116 is formed in the groove space 125 defined by the adjacent first banks 115 (step S8). The hole transport layer or the hole injection / transport layer 116 is formed by a printing method (coating method), and a groove between the adjacent first banks 115 is filled with ink containing a constituent material for the hole transport layer or the hole injection / transport layer 116. It is done by baking after applying to the space.

Although this process will be described in detail later, the hole transport layer or the hole injection / transport layer 116 is also formed on the second bank 114 exposed in the groove space defined by the two adjacent first banks 115. Form.
Similarly, the organic light emitting layer 117 and the electron transport layer 118 are sequentially stacked in the groove space 125 defined by the adjacent first banks 115 (steps S9 and S10). The organic light emitting layer 117 and the electron transport layer 118 are also formed by applying an ink containing each constituent material and baking it as described above.

Next, the cathode 119 and the sealing layer 120 are sequentially stacked so as to cover the electron transport layer 118 and the top surfaces of the first banks 115 (steps S11 and S12). The cathode 119 and the sealing layer 120 can be formed using, for example, a sputtering method.
Thereafter, the display panel 10 is completed by bonding the color filter substrate on which the color filter layer 123 and the black matrix layer 122 are formed to the substrate 124 (step S13).

The dimensions of the first bank 115, the second bank 114, and the sub-pixel region 12 to be formed will be exemplified below.
The first bank 115 has a height (height from the upper surface of the interlayer insulating layer 102) of 1 μm and a width of 30 μm.
The second bank 114 has a height (height from the upper surface of the interlayer insulating layer 102) of 0.5 μm and a width of 15 to 20 μm.

The sub-pixel 11 has a length (Y direction length) of 300 μm and a width (X direction width) of 50 μm.
5. Step of Forming Hole Transport Layer or Hole Injection / Transport Layer 116 First, the ink coating apparatus 200 used in the step of forming the hole transport layer or hole injection / transport layer 116 (step S8) will be described.
(Configuration of ink coating apparatus 200)
FIG. 6 is a diagram illustrating a main configuration of the ink application device.

As shown in the drawing, the ink application device 200 includes a work table 210 on which a bank-attached substrate 150 that is an application target is placed, and a head unit 220 having a plurality of nozzles that eject ink.
The work table 210 is a so-called gantry-type work table, and includes a base 211 on which a discharge target is placed and a long movable base 212 arranged above the base 211.

In FIG. 6, a bank-equipped substrate 150 is placed as an ejection target.
The movable base 212 is bridged between a pair of guide shafts 213a and 213b arranged in parallel along the longitudinal direction (X direction) of the base 211. The pair of guide shafts 213 a and 213 b are supported by columnar stands 214 a to 214 d disposed at the four corners of the base 211. The movable base 212 can be driven in the X direction along the guide shafts 213a and 213b by the linear motor portions 215a and 215b.

An L-shaped pedestal 216 is attached to the movable frame 212, and the head unit 220 is attached to the pedestal 216.
Therefore, the head unit 220 can be driven in the X direction and the Y direction by driving the linear motor units 215a and 215b and the servo motor unit 217.
In the head part 220, the first nozzle head 221 and the second nozzle head 222 are provided at a distance from each other.
The first nozzle head 221 and the second nozzle head 222 are attached to the base 216 via the head controller 223.
The head controller 223 includes a drive circuit that individually drives the discharge mechanism of each nozzle, and can rotate the first nozzle head 221 and the second nozzle head 222 along the XY plane, and the rotation angle thereof can be changed. By adjusting, the nozzle pitch with respect to the discharge target of the 1st nozzle head 221 and the 2nd nozzle head 222 can be adjusted now.

The linear motor units 215a and 215b, the servo motor unit 217, and the head control unit 223 are connected to the drive control unit via communication cables 201, 202, and 203.
Details of the head unit 220:
In the head part 220, a first nozzle head 221 and a second nozzle head 222 are provided with an interval in the X direction. Each of the first nozzle head 221 and the second nozzle head 222 is a long member extending in the Y direction, and ink is supplied from the outside via the infusion tubes 204 and 205.

Although not shown in FIG. 6, a plurality of nozzles 225 constituting the first nozzle group are provided distributed along the Y direction on the lower surface side of the first nozzle head 221, and the lower surface of the second nozzle head 222. On the side, a plurality of nozzles 226 constituting the second nozzle group are mainly distributed along the Y direction (see FIG. 7).
Each nozzle 225, 226 is provided with a mechanism (not shown) for ejecting ink having piezoelectric elements, liquid chambers, and the like as constituent elements.

  In the example shown in FIGS. 7A and 7B, the plurality of nozzles 225 and the plurality of nozzles 226 are arranged in a line along the Y direction, respectively. Is not limited to one row, and may be arranged in a plurality of rows. The arrangement direction of the plurality of nozzles 225 and the plurality of nozzles 226 may be inclined with respect to the Y direction.

In such an ink application device 200, the head unit 220 can be moved relative to the application object on the work table 210 along the XY plane.
As will be described in detail later, as shown in FIG. 7, using this ink coating apparatus 200, each nozzle 225 is placed at the landing position of the banked substrate 150 to be coated while the nozzle heads 221 and 222 are scanned in the X direction. 226, ink is ejected at a predetermined timing.

The plurality of nozzles 225 and 226 provided in the first nozzle head 221 and the second nozzle head 222 can be set to be used / not used individually, and ink is ejected only from the nozzles set to use. It is like that.
In this ink coating apparatus 200, the head unit 220 moves in the X direction. However, the base 211 may be moved in the X direction. The first nozzle head 221 and the second nozzle head 222 can be relatively scanned in the X direction.

A method for applying the ink for the hole transport layer or the hole injection / transport layer to the banked substrate 150 using such an ink application apparatus 200 will be described below.
(Ink application by the ink application apparatus 200)
As shown in FIG. 6, the banked substrate 150 is placed on the base 211 in the ink coating apparatus 200. At this time, the first nozzle head 221 and the second nozzle head 222 are placed so that the extending direction thereof is along the extending direction (Y direction) of the first bank 115 in the bank-equipped substrate 150.

  Then, the head unit 220 is scanned in the X direction (the direction perpendicular to the Y direction along the substrate surface of the banked substrate 150), or the head unit 220 is fixed and the base 211 is scanned in the X direction. The hole transport layer or the hole injection / transport layer ink is applied from the first nozzle head 221 and the second nozzle head 222 to each groove space 125 of the banked substrate 150. FIG. 5 schematically shows a state where the first nozzle head 221 and the second nozzle head 222 are scanned over the banked substrate 150.

As described above, the first nozzle head 221 and the second nozzle head 222 are scanned from the first nozzle head 221 and the second nozzle head 222 while the first nozzle head 221 and the second nozzle head 222 are scanned relative to the bank-equipped substrate 150. Application is performed by discharging ink into the groove space 125.
7A is a plan view showing a state in which ink is applied from the first nozzle head 221 to the groove space 125, and FIG. 7B is a plan view showing a state in which ink is applied from the second nozzle head 222 to the groove space 125. FIGS. 8A and 8B are schematic cross-sectional views showing a state in which ink is applied from the first nozzle head 221 onto the second bank 114. FIGS. 9A to 9C are schematic cross-sectional views showing how ink is applied from the second nozzle head 222 to the groove space 125.

In each groove space 125, the ink landing position (landing position) is indicated by a circle in FIGS. 7 (a) and 7 (b), and indicated by an arrow in FIGS. 8 (a) and 9 (a). Yes.
The ink (first ink) ejected from the first nozzle head 221 is a solution obtained by dissolving the material of the hole transport layer or the hole injection / transport layer 116 in a solvent.
When viewed from each groove space 125, the first nozzle head 221 first discharges the first ink while passing over the groove space 125, and after a predetermined time, the second nozzle head 222 moves above the groove space 125. The second ink is ejected while passing through. The predetermined time is, for example, 0.5 seconds. This time becomes longer as the interval between the first nozzle head 221 and the second nozzle head 222 is larger and the scanning speed is slower.

  Here, the first nozzle head 221 selectively applies ink onto the second bank 114 in each groove space 125. That is, from the first nozzle head 221, ink is applied on the second bank 114 in the entire groove space 125, and ink is applied to the area other than the second bank 114 (subpixel area 12). Even if it is not applied or applied, the application amount is reduced.

In the example shown in FIG. 7A, among the plurality of nozzles 225 (first nozzle group) provided in the first nozzle head 221, the nozzle 225 with a cross (×) is not used and the second bank 114 is scanned. Ink is landed on the second bank 114 using only the passing nozzle 225.
More specifically, the amount of ink applied on each second bank 114 in the groove space 125 is one or more drops. When a plurality of droplets are dropped on each second bank 114, the dropping position may be one row or two rows as shown in FIG.

The ink layer 116a may cover only a part of the surface of the second bank 114 exposed in the groove space 125, or the ink layer 116a is exposed in the groove space 125 as in the example shown in FIG. The entire surface of the second bank 114 may be covered.
In the example shown in FIG. 8B, the ink layer 116 a is formed not only on the second bank 114 but also across the peripheral portion of the subpixel region 12. As described above, the ink layer 116a may straddle the peripheral portion of the sub-pixel region 12, but the ink layers 116a applied on the second banks adjacent in the Y direction are separated from each other so as not to be connected. To.

On the other hand, the second nozzle head 222 applies the second ink to the entire groove space 125 from the second nozzle group (a plurality of nozzles 226).
FIG. 7B illustrates a landing position where ink droplets are landed from the second nozzle head 222 in each groove space 125.
As shown in FIG. 7B, the second ink is applied to the entire region in the groove space 125 using the plurality of nozzles 226 provided in the second nozzle head 222 as a whole.

The second ink used here is also a solution obtained by dissolving the material of the hole transport layer or the hole injection / transport layer 116 in a solvent. The second ink may have the same composition as the first ink ejected from the first nozzle head 221 (that is, the same type of solvent), or the type of solvent may be different.
When inks having the same composition are used as the first ink and the second ink, the ink is supplied from the common ink tank to the first nozzle head 221 and the second nozzle head 222 via the infusion tubes 204 and 205. Also good.

9A to 9C, ink is applied from the second nozzle head 222 to the entire groove space 125, and the applied ink layer is dried to form the hole transport layer or the hole injection / transport layer 116. It is a cross-sectional schematic diagram which shows a mode.
FIG. 9B shows a state in which an ink layer 116 b that is continuous in the Y direction is formed in the groove space 125 as a result of ink being applied from above the ink layer 116 a from the second nozzle head 222. The height of the ink layer 116b immediately after application is, for example, about 20 μm.

By drying the applied ink layer 116b, a hole transport layer or a hole injection / transport layer 116 continuous in the Y direction is formed in the groove space 125, as shown in FIG. 9C.
The ink layer 116b is also preferably dried by drying under reduced pressure.
The thickness of the hole transport layer or hole injection / transport layer 116 after drying is several tens of nm (for example, 20 nm).

6). Effects of the hole transport layer or hole injection / transport layer 116 forming method According to the hole transport layer or hole injection / transport layer 116 forming method, ink is applied from the first nozzle head 221 in each groove space 125. The ink layer 116 a is formed on the second bank 114, and then the ink layer 116 b is formed in the entire groove space 125 by ink application from the second nozzle head 222. In other words, since the ink is applied twice on the second bank 114 in each groove space 125, the ink is prevented from getting wet near the second bank 114. Therefore, luminance unevenness can be prevented within the pixel.

This effect will be described below in comparison with a comparative example.
In the method for forming the hole transport layer or the hole injection / transport layer 116 according to the comparative example, the hole transport layer or the hole injection / transport layer 116 forming ink is applied to the entire groove space 125 at a time.
FIG. 10A is a plan view showing an ink layer formed in the groove space 125 by the method for forming the hole transport layer or hole injection / transport layer 116 according to the comparative example.

Since the second bank 114 protrudes in the groove space 125 (see FIG. 8), there is a step at the edge of the second bank 114. Since this step portion is difficult to apply ink, in the ink layer formed by applying the ink to the groove space 125 only once, as shown in FIG. 10A, there is an unwet area near the edge of the second bank 114. May occur.
And, in the groove space 125, the amount of coating is less in the portion where the non-wetting region occurs than in the portion where the non-wetting region does not occur. As a result, the hole transport layer or the hole injection / hole injection between the sub-pixels. Variations in the thickness of the transport layer 116 occur.

When the display panel 10 is manufactured using the hole transport layer or the hole injection / transport layer 116 having a variation in film thickness as described above, the luminance varies among the sub-pixels.
Further, when a portion with a very thin film thickness of the hole transport layer or the hole injection / transport layer 116 is generated in the peripheral region of the subpixel, when the display panel 10 is manufactured using the portion, the light emission is performed at the thin film portion. It becomes abnormal and causes uneven brightness.

  In contrast, according to the method for forming the hole transport layer or the hole injection / transport layer 116 according to the embodiment, ink is selectively transferred from the first nozzle head 221 to the second bank 114 in the groove space 125. By applying, an ink layer 116a is formed on the second bank 114 as shown in FIG. Then, ink is applied from the second nozzle head 222 to the entire groove space 125, whereby an ink layer 116b is formed in the entire groove space 125 as shown in FIG.

At this time, since the ink is applied twice to the second bank 114 in each groove space 125, the ink is prevented from getting wet near the second bank 114.
There is no occurrence of an unwetted area where no ink layer is present on the second bank 114 at the periphery of the pixel in the ink layer 116b, and the hole transport layer or the hole injection / transport layer 116 is thin in the peripheral area of the pixel. This phenomenon is also suppressed.

Therefore, it is possible to suppress the occurrence of luminance unevenness in the pixel when the display panel 10 is manufactured.
In the hole transport layer or the hole injection / transport layer 116, the portion existing above the second bank does not contribute to light emission, but does not adversely affect the light emission characteristics.
7). Modifications, etc. (1) FIG. 11 is a diagram showing an ink application method according to a modification.

  In the above embodiment, the ink application apparatus is provided with the first nozzle head 221 in the front of the scanning direction (X direction), the second nozzle head 222 in the rear, and the first nozzle group including the nozzle 225 in the first nozzle head 221. In this modification, a plurality of nozzle heads 224A to 224E are arranged in the Y direction in the head portion, and each nozzle is provided with the second nozzle head 222. In the heads 224A to 224E, a nozzle 225 constituting the first nozzle group is provided in front of the scanning direction (X direction), and a nozzle 226 constituting the second nozzle group formed from the rear is provided.

Therefore, the first nozzle group includes a plurality of nozzles 225 that exist in the plurality of nozzle heads 224A to 224E, and the second nozzle group also includes a plurality of nozzles 226 that exist in the plurality of nozzle heads 224A to 224E. Yes.
The hole transport layer or the hole injection described in the above embodiment can be obtained by scanning the head unit including the plurality of nozzle heads 224A to 224E or by scanning the base 211 while fixing the head unit. The ink application method for the cum-transport layer can be carried out.

That is, while scanning the nozzle heads 224 </ b> A to 224 </ b> E, first, the nozzles 225 that pass over the second bank 114 in the first nozzle group (displayed by large circles in FIG. 11) in each groove space 125. Ink is applied onto the second bank 114. Subsequently, ink is applied to the entire groove space 125 from the nozzles 226 of the second nozzle group.
Thus, the same effect as described in the above embodiment can be obtained.

  (2) According to the method for forming the hole transport layer or the hole injection / transport layer 116 according to the above embodiment, the first nozzle head 221 is positioned forward of the second nozzle head 222 in the scanning direction, After the ink is selectively applied from the first nozzle head 221 to the second bank 114 in the groove space 125, the ink is applied from the second nozzle head 222 to the entire groove space 125. However, the order may be changed. .

  That is, the second nozzle head 222 is disposed in front of the first nozzle head 221 in the scanning direction, and after the ink is applied from the second nozzle head 222 to the entire groove space 125, the first nozzle head 221 enters the groove space 125. Ink may be selectively applied onto the second bank 114 in FIG. Also in this case, in each groove space 125, the ink is applied twice on the second bank, so even if the second bank is uncoated by the first ink application, the second ink application is performed. Unwetting may be resolved. Accordingly, an effect of reducing the occurrence of ink non-wetting can be obtained.

However, it is considered that the effect of preventing unwetting on the second bank 114 is greater when the ink is first selectively applied onto the second bank 114 as in the above embodiment.
(3) In the method for forming the hole transport layer or hole injection / transport layer 116 according to the above embodiment, if a fast-drying ink is used as the ink ejected from the first nozzle head 221 onto the second bank 114,
Ink may be dried to some extent until it is applied from the second nozzle head 222 (for example, 0.5 seconds) to form a coating film. Then, after the ink coating is formed on the second bank 114, the ink is applied to the entire groove space 125 from the second nozzle head 222.

In this case, the following actions and effects can be expected.
When forming functionalities by applying functional layer ink to each groove space 125, there are the following factors that cause the thickness of the formed functional layer to vary between pixels.
When ink is applied to the entire groove space between the first banks, the applied ink layer also covers the second bank, but the volume of the ink decreases in the process of drying the ink layer, so that the drying progresses to some extent. At this stage, the ink layer on the second bank is distributed in such a manner that it is drawn into the ink layers in the pixel regions on both sides of the second bank.

At this time, it suffices that half of the pixels are distributed to the adjacent pixel regions, but the distribution may be uneven. In that case, the amount of ink in the pixel regions on both sides becomes non-uniform, and the thickness of the formed functional layer is different.
On the other hand, when fast-drying ink is applied on the second bank 114, a lower layer which is a part of the functional layer is formed on the second bank, and a groove space is formed on the second bank from the second nozzle head 222. The ink is applied to the entire 125.

When the ink layer applied from the second nozzle head 222 dries, even if the ink layer tends to shrink, the lower layer has affinity for the ink layer, so the ink layer is attached on the lower layer Is maintained, and the functional layer remains on the lower layer.
As a result, variation in the thickness of the functional layer between pixel regions adjacent to each other across the second bank is suppressed, and the uniformity of the thickness is improved.

  (4) By changing the bank material used for the first bank and the second bank, or by changing the UV processing conditions for the first bank and the second bank, the ink in the second bank can be compared with the first bank. You may adjust so that the liquid repellency with respect to may become low. This improves ink wetting on the second bank. The effect of suppressing variations in film thickness of the hole transport layer or the hole injection / transport layer 116 can be further enhanced.

  (5) In the above embodiment, the case where the hole transport layer or the hole injection / transport layer 116 of the display panel 10 is formed by the wet method has been described, but the functional layer other than the hole transport layer or the hole injection / transport layer is formed by the wet method. For example, when the light emitting layer, the hole injection layer, the electron transport layer, and the electron injection layer are formed by a wet method, the same effect can be obtained and the same effect can be obtained.

Further, the present invention is not limited to the organic EL display panel, and can be applied to, for example, a case where a functional layer in organic EL illumination is formed, and the same effect can be obtained.
(6) In the above embodiment, the case where the functional layer of the top emission type display panel 10 is formed has been described as an example. However, the embodiment can also be applied to form the functional layer of the bottom emission type display panel. Similar effects can be obtained.

  The method for forming a functional layer according to the present invention is useful for manufacturing an organic light emitting device such as an organic EL display device.

DESCRIPTION OF SYMBOLS 1 Organic electroluminescent display device 10 Display panel 11 Sub pixel 12 Sub pixel area | region 100 Substrate 102 Interlayer insulation layer 103 Anode 104 Hole injection layer 110 TFT substrate 114 Second bank 115 First bank 116a, 116b Ink layer 116 Hole transport layer or hole injection Cumulative transport layer 117 Organic light emitting layer 118 Electron transport layer 119 Cathode 125 Groove space 150 Banked substrate 200 Ink application device 211 Base 220 Head portion 221 First nozzle head 222 Second nozzle heads 224A to 224E Nozzle head 225 First nozzle group Nozzle 226 Nozzle of second nozzle group

Claims (10)

A base substrate, a plurality of first banks extending in a first direction along the surface of the base substrate, and a groove space defined by the plurality of first banks are spaced in the first direction. A substrate with a bank having a plurality of second banks formed and forming a functional layer of an organic light emitting device in each groove space,
A head unit provided with a first nozzle group composed of a plurality of nozzles distributed along the first direction and a second nozzle group composed of a plurality of nozzles distributed in the first direction; While scanning in a second direction that intersects the first direction along the surface of the substrate,
The first nozzle group is used to selectively apply the first ink containing the material of the functional layer on the plurality of second banks in each groove space of the banked substrate, and the second nozzle group The second ink containing the material of the functional layer is applied to the entire groove space of the banked substrate using
Forming the functional layer by drying the first ink and the second ink applied to each groove space;
A method for forming a functional layer. In the head part,
A nozzle head comprising the first nozzle group and a nozzle head comprising the second nozzle group,
Provided in the second direction at a distance from each other,
The method for forming a functional layer according to claim 1. In the head part,
A plurality of nozzle heads are provided side by side in the first direction,
Some nozzles provided in each nozzle head constitute the first nozzle group,
The remaining nozzles constitute the second nozzle group,
The method for forming a functional layer according to claim 1. In the head portion, the first nozzle group is present in the scanning direction ahead of the second nozzle group,
For each groove space,
After selectively applying the first ink on the plurality of second banks using the first nozzle group,
Applying the second ink to the entirety of the groove spaces using the second nozzle group;
The method for forming a functional layer according to claim 1. When the first ink is applied to each groove space, the first ink applied on the second banks adjacent to each other is applied so as not to contact each other.
The method for forming a functional layer according to claim 4. When applying the second ink to each groove space,
Applying the applied second ink so as to be continuous in the first direction;
The method for forming a functional layer according to claim 1. The first ink and the second ink have the same composition.
The formation method of the functional layer in any one of Claims 1-6. The second bank is lower in height from the surface of the base substrate than the first bank.
The method for forming a functional layer according to claim 1. The second bank has less liquid repellency with respect to the first ink than the first bank.
The method for forming a functional layer according to claim 1. A method of manufacturing an organic light emitting device by forming a functional layer on a base substrate,
When forming the functional layer, the method for forming a functional layer according to claim 1 is used.
Manufacturing method of organic light emitting device.

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