JP2021150118A - Manufacturing method of self-luminous panel and self-luminous panel - Google Patents

Abstract

To prevent an abnormal pixel from being formed by a minute quantity of ink in a self-luminous panel in which a light-emitting layer is formed by a wet process.SOLUTION: In a manufacturing method of a self-luminous panel, a plurality of partition walls which extend in a column direction and divide pixel electrodes in a row direction are formed on a substrate. A first light-emitting layer is formed by applying a first ink containing a first light-emitting material to a first clearance in a clearance between two partition walls adjacent in the row direction. A second light-emitting layer is formed by applying a second ink containing a second light-emitting material of which the light-emitting wavelength is longer than that of the first light-emitting material, to a second clearance which is adjacent to the first clearance in the row direction after the application of the first ink.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to a method for manufacturing a display panel using a self-luminous element utilizing an electroluminescent phenomenon and a quantum dot effect, and a self-luminous panel.

In recent years, display devices using self-luminous elements such as organic EL elements utilizing the electroluminescent phenomenon of organic materials and QLEDs utilizing the quantum dot effect are becoming widespread.

The self-luminous element has a structure in which at least a light emitting layer is sandwiched between an anode and a cathode. Currently, as a method for efficiently forming a functional layer including a light emitting layer, an ink containing a functional material is applied by a wet process to form the functional layer. In the wet process, the manufacturing equipment can be miniaturized as compared with the vacuum vapor deposition equipment, and it is not necessary to use the shadow mask used when depositing the functional material. Therefore, there is no need to perform work such as positioning the shadow mask, and it is easy to manufacture a large substrate with a mixture of panel sizes in consideration of mass productivity and mass productivity, which is suitable for efficient panel generation. .. Further, unlike the thin-film deposition method, in the wet process, the efficiency of using functional materials such as expensive light-emitting materials is improved, so that the panel manufacturing cost can be reduced.

International Publication No. 2004/03417 JP-A-2002-131259

In the wet process, by applying ink containing a functional material in units of coating areas defined by partition walls (banks), separate printing is performed and multiple types of self-luminous elements with different emission colors are printed on one panel. Form. However, due to poor printing process such as poor bank formation and misalignment of the ink application position, the ink applied to the two areas to be partitioned may be mixed and poor panel formation may occur. In particular, when a color mixture in which inks for forming a light emitting layer are mixed occurs, the self-luminous element may develop a color different from the intended color, which may cause a serious display defect. On the other hand, the color mixture of the inks cannot always be determined by the appearance, and especially when the amount of mixed ink is very small, even if the light emitting layer looks normal in appearance, it becomes an abnormal pixel that emits an unintended color. There is. When such a color mixture that looks normal in appearance occurs, it cannot be detected by the visual inspection and the existence of abnormal pixels is confirmed only when the power is turned on. Therefore, the detection of defects in the printing process is delayed and the manufacturing efficiency (yield) deteriorates. It can be a cause of causing.

The present disclosure has been made in view of the above problems, and is a method for manufacturing a self-luminous panel that suppresses the formation of abnormal pixels caused by a small amount of ink in a self-luminous panel that forms a light emitting layer by a wet process, and a method for manufacturing the self-luminous panel. , Aim to provide a self-luminous panel.

In the method for manufacturing a self-luminous panel according to one aspect of the present disclosure, a substrate is prepared, pixel electrodes are formed in a matrix on the substrate, stretched in the column direction, and a partition wall for partitioning the pixel electrodes in the row direction is provided. A plurality of the first light emitting layer is formed by applying a first ink containing a first light emitting material to the first gap among the gaps between two partition walls adjacent to each other in the row direction to form the first light emitting layer. After the ink is applied, a second ink containing a second light emitting material having a longer emission wavelength than the first light emitting material is applied to the second gap adjacent to the first gap in the row direction to emit a second light. A first light emitting element that forms a layer, forms a counter electrode above the first light emitting layer and the second light emitting layer, and includes the pixel electrode, the first light emitting layer, and the counter electrode. The emission color inspection is performed by lighting each of the pixel electrode, the second light emitting layer, and the second light emitting element including the counter electrode to inspect the emission color.

According to the method for manufacturing a self-luminous panel of the above aspect, even when a small amount of the first light emitting material is mixed in the second light emitting layer, the self-luminous element having the second light emitting layer emits light of the second light emitting material. It emits light in color. Therefore, even if a film forming defect occurs in which a small amount of film is accidentally applied to the second gap when the ink containing the first light emitting material is applied, a self-luminous element formed at the location where the film forming defect occurs is designed. Since it has the same performance as the self-luminous panel, it is a good product, and it is possible to suppress the occurrence of abnormal pixels that cannot be detected by the visual inspection.

It is the schematic of the display device 1 including the self-luminous panel 10 which concerns on embodiment. It is a top view of the plan of the self-luminous panel 10 which concerns on embodiment. It is a partial cross-sectional view of the self-luminous panel 10 according to the embodiment, and corresponds to the AA cross section of FIG. It is a partial cross-sectional view schematically showing a part of the film forming process of a light emitting layer 17. It is a partial cross-sectional view which shows a part of the film formation process of a light emitting layer 17 schematically, and shows the state which the bridge color mixing occurred at the time of forming the light emitting layer 17X. It is a partial cross-sectional view which shows a part of the film formation process of a light emitting layer 17 schematically, and shows the state which a trace color mixing occurred at the time of forming the light emitting layer 17X. It is a partial cross-sectional view which shows a part of the film formation process of a light emitting layer 17 schematically, and shows the state which the bridge color mixing occurred at the time of forming the light emitting layer 17Y. It is a partial cross-sectional view which shows a part of the film formation process of a light emitting layer 17 schematically, and shows the state which the bridge color mixing occurred at the time of forming the light emitting layer 17Y. It is a partial plan view which shows a part of the self-luminous panel 10 when the bridge color mixing occurs. It is a partial plan view schematically showing a part of a self-luminous panel 10 when a slight amount of color mixing occurs. It is a flowchart which shows the manufacturing process of the self-luminous panel which concerns on embodiment. It is a partial cross-sectional view which shows a part of the manufacturing process of the self-luminous panel which concerns on embodiment. (A) is a partial cross-sectional view showing a state in which a TFT layer is formed on a base material. (B) is a partial cross-sectional view showing a state in which an interlayer insulating layer is formed on the TFT layer. (C) is a partial cross-sectional view showing a state in which a pixel electrode material layer is formed on an interlayer insulating layer. (D) is a partial cross-sectional view showing a state in which the pixel electrode material layer is patterned to form the pixel electrode. (E) is a partial cross-sectional view showing a state in which a partition wall material layer is formed on a pixel electrode and an interlayer insulating layer. It is a partial cross-sectional view which shows a part of the manufacturing process of the self-luminous panel which concerns on embodiment. (A) is a partial cross-sectional view showing a state in which a partition wall is formed. (B) is a partial cross-sectional view showing a state in which the material ink of the hole injection layer is applied into the opening of the partition wall to form the hole injection layer. (C) is a partial cross-sectional view showing a state in which the material ink of the hole transport layer is applied into the opening of the partition wall to form the hole transport layer. It is a partial cross-sectional view which shows a part of the manufacturing process of the self-luminous panel which concerns on embodiment. (A) is a partial cross-sectional view showing a state in which a light emitting layer is formed in an opening of a partition wall. (B) is a partial cross-sectional view showing a state in which an electron transport layer is formed on a partition wall and a light emitting layer. (C) is a partial cross-sectional view showing a state in which an electron injection layer is formed on an electron transport layer. It is a partial cross-sectional view which shows a part of the manufacturing process of the self-luminous panel which concerns on embodiment. (A) is a partial cross-sectional view showing a state in which a counter electrode is formed on the electron injection layer. (B) is a partial cross-sectional view showing a state in which a sealing layer is formed on the counter electrode.

<< Background to one aspect of this disclosure >>
When the functional layer is formed by the coating method, the ink in which the material is dissolved is applied to the partition gap. Hereinafter, the functional layer formed by the coating method in this way is referred to as a coating film. As described above, since the partition wall prevents the ink from getting over and defines the formation range of the coating film, if a defect occurs, it may cause a serious display defect such as color mixing due to the mixing of the ink. Further, when the ink is applied and when the ink is applied to a place other than the intended partition wall gap, there is a possibility of causing serious display defects such as color mixing due to the mixing of the inks.

On the other hand, the color mixing by mixing the light emitting layer forming ink is a large-scale color mixing (hereinafter referred to as "bridge color mixing") that occurs when the ink flows and is exchanged between the two partition gaps partitioned by the partition walls. ) And a minute color mixing (hereinafter referred to as "trace color mixing") that occurs when only a small amount of unintended ink is mixed in one partition gap. Bridge color mixing occurs when the ink that has passed over the defective part of the partition wall or the ink that has been dropped on the partition wall becomes an ink passage (bridge) and the ink flows and is exchanged between the two partition wall gaps. It is a factor that causes color abnormalities over a wide area. On the other hand, in bridge color mixing, a large amount of unintended ink flows into any of the partition gaps, so that the appearance of the light emitting layer is different from the appearance of a normal light emitting layer. ) It can be found by visual inspection of the equipment. Therefore, it is possible to detect an abnormality by performing an visual inspection of the light emitting layer after the completion of the light emitting layer forming process, and when the abnormal panel is excluded from the subsequent manufacturing process and the cause is an abnormality in the coating process. It is easy to suppress the manufacture of similar abnormal panels such as inspection of coating equipment and review of settings.

On the other hand, the trace color mixing occurs when a small amount of the ink forming the light emitting layer is erroneously dropped into the partition gap which is not intended, and unlike the bridge color mixing, the ink does not flow out. That is, in a small amount of color mixing, the amount of unintended ink is a minute amount that does not cause ink overflow, and the appearance of the light emitting layer is almost the same as the appearance of a normal light emitting layer, and it is difficult to find it even with an AOI device. Is. On the other hand, in the case of a small amount of color mixing, an emission color abnormality may occur in which the emission color does not become the intended color depending on the combination of the original emission color and the emission color of the emission material contained in the mixed ink. However, since it is necessary to inject an electric current into the self-luminous element in order to inspect the emission color, it is necessary to connect to the drive control circuit after the manufacture of the self-luminous panel is completed. Therefore, when a small amount of color mixing occurs repeatedly due to an abnormality in the coating device or the like, it takes time from the manufacture of the defective panel to the detection of the abnormality, so that the same defective panel is manufactured during that time, and the yield is increased. May occur. On the other hand, if the next panel is not manufactured from the completion of the coating process of the light emitting layer until the emission color inspection is performed, a huge waiting time is generated and the manufacturing efficiency is significantly lowered.

In view of the above problems, the inventor has studied a manufacturing method for preventing color development abnormality due to a slight amount of color mixing, and has reached the present disclosure.

≪Aspect of disclosure≫
In the method for manufacturing a self-luminous panel according to one aspect of the present disclosure, a substrate is prepared, pixel electrodes are formed in a matrix on the substrate, stretched in the column direction, and a partition wall for partitioning the pixel electrodes in the row direction is provided. A plurality of the first light emitting layer is formed by applying a first ink containing a first light emitting material to the first gap among the gaps between two partition walls adjacent to each other in the row direction to form the first light emitting layer. After the ink is applied, a second ink containing a second light emitting material having a longer emission wavelength than the first light emitting material is applied to the second gap adjacent to the first gap in the row direction to emit a second light. A first light emitting element that forms a layer, forms a counter electrode above the first light emitting layer and the second light emitting layer, and includes the pixel electrode, the first light emitting layer, and the counter electrode. The emission color inspection is performed by lighting each of the pixel electrode, the second light emitting layer, and the second light emitting element including the counter electrode to inspect the emission color.

According to the method for manufacturing a self-luminous panel of the above aspect, even when a small amount of the first light emitting material is mixed in the second light emitting layer, the self-luminous element having the second light emitting layer emits light of the second light emitting material. It emits light in color. Therefore, even if a film forming defect occurs in which a small amount of film is accidentally applied to the second gap when the ink containing the first light emitting material is applied, a self-luminous element formed at the location where the film forming defect occurs is designed. Since it has the same performance as the self-luminous panel, it is a good product, and it is possible to suppress the occurrence of abnormal pixels that cannot be detected by the visual inspection.

Further, in the method for manufacturing a self-luminous panel according to the above aspect, the following may be used.

In the emission color inspection, if the emission color of the light emitting element formed in the second gap is the same as the emission color of the second element, is the first ink erroneously mixed in the second gap? Regardless of whether or not, the light emitting element formed in the second gap may be determined to be the normal second light emitting element.

As a result, even if a minute abnormality occurs in the film forming process of the first light emitting layer, if it can be regarded as a non-defective product in the emission color inspection, unnecessary disposal is not generated, so that the yield of the product can be improved.

Further, after the formation of the second light emitting layer, the appearance of each of the first light emitting layer and the second light emitting layer is inspected, and the first gap is between the first gap and the second gap. When it is confirmed that the ink and the second ink are mixed, the appearance of determining that there is an abnormality in the first light emitting layer in the first gap and the second light emitting layer in the second gap. Further inspection may be performed.

As a result, if it can be determined by the visual inspection that the film formation abnormality of the first light emitting layer and the second light emitting layer has occurred, it can be discarded as a defective panel without performing the light emitting color inspection. It is possible to suppress the execution of the necessary emission color inspection.

Further, when it is determined in the visual inspection that there is an abnormality in the first light emitting layer and / or the second light emitting layer, the production of the self-luminous panel may be discontinued.

As a result, by disposing of the panel judged as a defective panel in the visual inspection without performing the remaining manufacturing process, it is possible to suppress the execution of unnecessary processes and prevent unnecessary costs from being generated. Can be done.

The self-luminous panel according to one aspect of the present disclosure includes a light emitting element that emits light in a first color in a display region on a substrate and a light emitting element that emits light in a second color that is longer than the wavelength of the first color. A self-luminous panel comprising the above, wherein the first light emitting element that emits light in the first color includes a first light emitting layer and a pair of electrodes facing each other via the first light emitting layer. The second light emitting element that emits light in the second color includes the second light emitting layer and a pair of electrodes facing each other via the second light emitting layer, and the first light emitting layer and the said Separated from the second light emitting layer by a partition wall, the first light emitting layer is a coating film and contains a first light emitting material, and the second light emitting layer is a coating film and is a second light emitting layer. It is characterized by containing a light emitting material of the above and a trace amount of the first light emitting material.

According to the self-luminous panel of the above aspect, even if a small amount of the first light emitting material is mixed in the second light emitting layer, if it emits light in the light emitting color of the second light emitting material, it can be regarded as a non-defective panel. Therefore, the yield of the product can be improved.

Further, in the self-luminous panel of the above aspect, the following may be performed.

A third light emitting element including a third light emitting layer and a pair of electrodes facing each other via the third light emitting layer is further included, and the third light emitting layer is a coating film and is said to be the third light emitting layer. The third light emitting element may emit light in the second color, including the second light emitting material and not containing the first light emitting material.

As a result, when the emission colors of the second light emitting element and the third light emitting element are the same, they can be treated as the same type of light emitting element.

Further, the partition wall is extended in the row direction, and a plurality of the first light emitting elements are arranged in a row in the gap between the partition wall and the second partition wall extending in the row direction, and the partition wall is extended in the row direction. The second light emitting element may be arranged in the gap with the third partition wall.

As a result, since the area of the coating region where the light emitting layer should be formed is larger than the area of the light emitting element, the influence of the slight color mixing is relatively small, and even if color mixing occurs, it can be treated as the second light emitting element. The possibility of being able to do it increases.

Further, both the first light emitting material and the second light emitting material may be organic materials that emit light by electroluminescence.

Thereby, the present embodiment can be realized in the coating type organic EL display panel.

<< Embodiment >>
Hereinafter, an embodiment of a display device (hereinafter, simply referred to as “display device”) using an organic EL display panel as the self-luminous panel according to the present disclosure will be described.

<Display device configuration>
(1) Circuit Configuration of Display Device 1 FIG. 1 is a block diagram showing a circuit configuration of the display device 1.

As shown in FIG. 1, the display device 1 includes an organic EL display panel 10 (hereinafter, referred to as “display panel 10”) and a drive control circuit unit 200 connected to the organic EL display panel 10.

The display panel 10 is an organic EL (Electro Luminescence) panel that utilizes the electroluminescence phenomenon of an organic material, and is configured such that a plurality of organic EL elements are arranged in a matrix (matrix), for example.

The drive control circuit unit 200 is composed of four drive circuits 210 and a control circuit 220.

(2) Configuration of Display Panel 10 FIG. 2 is an enlarged schematic plan view of a part of the organic EL display panel 10. The organic EL display panel 10 has a partition wall (column bank) 14 that partitions the substrate in the row direction (X direction) and defines a coating area, and a pixel regulation layer (row bank) that partitions the substrate in the column direction (Y direction). ) 141 and partitions on the matrix. The region partitioned by the partition wall 14 and the pixel regulation layer 141 constitutes the sub-pixels 100R, 100G, and 100B, respectively, and the sub-pixels 100R, 100G, and 100B form the pixel P. Each of the sub-pixels 100R, 100G, and 100B is formed in each of the coating regions CR, CG, and CB, which are partitioned by two partition walls 14 adjacent to each other in the X direction.

(3) Configuration of Organic EL Element 2 FIG. 3 is a schematic cross-sectional view of a part of the organic EL display panel 10, and corresponds to the AA cross section of FIG. Each of the sub-pixels 100R, 100G, and 100B of the display panel 10 is composed of organic EL elements 2 (R), 2 (G), and 2 (B), which are self-luminous elements. Hereinafter, when the organic EL elements 2 (R), 2 (G), and 2 (B) are not distinguished from each other, the organic EL element 2 will be described.

The organic EL display panel 10 includes a substrate 11, an interlayer insulating layer 12, and a partition wall 14 in this order from the bottom, and has a pixel electrode 13 and a hole injection layer in an opening 14a partitioned by two partition walls adjacent to each other in the X direction. 15. The hole transport layer 16 and the light emitting layer 17 are provided, and as common layers, an electron transport layer 18, an electron injection layer 19, a counter electrode 20, and a sealing layer 21 are provided. Of these, the portion from the pixel electrode 13 to the counter electrode 20 constitutes the organic EL element 2.

<Each component of organic EL element>
(1) Substrate The substrate 11 includes a base material 111 which is an insulating material and a TFT (Thin Film Transistor) layer 112. A drive circuit is formed in the TFT layer 112 for each sub-pixel. The base material 111 includes, for example, a glass substrate, a quartz substrate, a silicon substrate, a molybdenum sulfide, copper, zinc, aluminum, stainless steel, a metal substrate such as magnesium, iron, nickel, gold, and silver, a semiconductor substrate such as gallium arsenic, and a plastic substrate. Etc. can be adopted.

As the plastic material, either a thermoplastic resin or a thermosetting resin may be used.

(2) Interlayer Insulation Layer The interlayer insulation layer 12 is formed on the substrate 11. The interlayer insulating layer 12 is made of a resin material and is for flattening a step on the upper surface of the TFT layer 112. Examples of the resin material include a positive type photosensitive material. Moreover, as such a photosensitive material, an acrylic resin, a polyimide resin, a siloxane resin, and a phenol resin can be mentioned. Further, although not shown in the cross-sectional view of FIG. 3, contact holes are formed in the interlayer insulating layer 12 for each sub-pixel.

(3) Pixel electrode (first electrode)
The pixel electrode 13 includes a metal layer made of a light-reflecting metal material and is formed on the interlayer insulating layer 12. The pixel electrode 13 is provided for each sub-pixel and is electrically connected to the TFT layer 112 through a contact hole (not shown).

In this embodiment, the pixel electrode 13 functions as an anode.

Specific examples of the metal material having light reflectivity include Ag (silver), Al (aluminum), aluminum alloy, Mo (molybdenum), APC (alloy of silver, palladium and copper), ARA (silver, rubidium, gold). , MoCr (alloy of molybdenum and chromium), MoW (alloy of molybdenum and tungsten), NiCr (alloy of nickel and chromium) and the like.

The pixel electrode 13 may be composed of a metal layer alone, but as a laminated structure in which a layer made of a metal oxide such as ITO (indium tin oxide) or IZO (indium tin oxide) is laminated on the metal layer. May be good.

(4) Partition wall and pixel regulation layer The partition wall 14 partitions a plurality of pixel electrodes 13 arranged for each sub-pixel above the substrate 11 for each row in the X direction (see FIG. 2), and is in the X direction. It is a line bank shape extending in the Y direction between the sub-pixel rows CR, CG, and CB arranged in the same direction. The partition wall 14 has an insulating property, and at least the surface thereof has a liquid repellency against the ink for forming a functional layer. The partition wall 14 is made of, for example, an insulating organic material (for example, acrylic resin, polyimide resin, siloxane resin, phenol resin, etc.). In this embodiment, a phenolic resin is used. The partition wall 14 may contain an additive having liquid repellency such as a fluorine-based surfactant, or may be surface-treated. The organic EL element 2 is formed in the opening 14a defined by the two partition walls 14 adjacent to each other in the X direction.

The pixel regulation layer 141 partitions the pixel electrodes 13 adjacent to each other in the Y direction in the opening 14a, suppresses the step breakage of the light emitting layer 17 in the sub-pixel rows CR, CG, and CB, and suppresses the step breakage of the light emitting layer 17, and the pixel electrodes 13 and the counter electrodes. It has a role of improving the electrical insulation between 20 and the like. The pixel regulation layer 141 has an insulating property. The material of the pixel regulation layer 141 may have a liquidity property with respect to the ink for forming the functional layer. The pixel regulation layer 141 is made of, for example, an insulating organic material, and for example, an acrylic resin is used.

(5) Hole Injection Layer The hole injection layer 15 is provided on the pixel electrode 13 for the purpose of promoting the injection of holes from the pixel electrode 13 into the light emitting layer 17. The hole injection layer 15 is formed by, for example, an oxide such as Ag (silver), Mo (molybdenum), Cr (chromium), V (vanadium), W (tungsten), Ni (nickel), Ir (iridium), or It is a layer made of a low molecular weight organic compound such as copper phthalocyanine (CuPc) and a polymer material such as polyethylene dioxythiophene / polystyrene sulphonic acid (PEDOT / PSS).

(6) Hole Transport Layer The hole transport layer 16 has a function of transporting holes injected from the hole injection layer 15 to the light emitting layer 17. The material of the hole transport layer 16 is, for example, an arylamine derivative, a fluorene derivative, a spiro derivative, a carbazole derivative, a pyridine derivative, a pyrazine derivative, a pyrimidine derivative, a triazine derivative, a quinoline derivative, a phenanthroline derivative, a phthalocyanine derivative, a porphyrin derivative, a silol derivative. , Oligothiophene derivatives, condensed polycyclic aromatic derivatives, metal complexes and the like.

(7) Light-emitting layer The light-emitting layer 17 is formed in the opening 14a and has a function of emitting light of each color of R, G, and B by recombination of holes and electrons. As the material of the light emitting layer 17, a known material can be used.

When the light emitting element 2 is an organic EL element, examples of the organic light emitting material contained in the light emitting layer 17 include an oxinoid compound, a perylene compound, a coumarin compound, an azacmarin compound, an oxazole compound, an oxaziazole compound, a perinone compound, and pyrolopyrrole. Compounds, naphthalene compounds, anthracene compounds, fluorene compounds, fluoranthene compounds, tetracene compounds, pyrene compounds, coronen compounds, quinolone compounds and azaquinolone compounds, pyrazoline derivatives and pyrazolone derivatives, rhodamine compounds, chrysene compounds, phenanthrene compounds, cyclopentadiene compounds, stillben compounds , Diphenylquinone compound, styryl compound, butadiene compound, dicyanomethylenepyran compound, dicyanomethylenethiopyran compound, fluorescein compound, pyririum compound, thiapyrrium compound, selenapyrium compound, tellropyrylium compound, aromatic aldaziene compound, oligophenylene compound, thioxanthene Fluorescent substances such as compounds, cyanine compounds, acrydin compounds, metal complexes of 8-hydroxyquinolin compounds, metal complexes of 2-bipyridine compounds, complexes of shift salts and Group III metals, oxine metal complexes, and rare earth complexes can be used. .. Further, a known phosphorescent substance such as a metal complex that emits phosphorescence such as tris (2-phenylpyridine) iridium can be used. Further, the light emitting layer 17 is formed by using polyfluorene or a derivative thereof, polyphenylene or a derivative thereof, a polymer compound such as polyarylamine or a derivative thereof, or a mixture of the low molecular weight compound and the high molecular weight compound. May be good. The light emitting element 2 may be a quantum dot light emitting element (QLED; Quantum-dot Light Emitting Diode), and a material having a quantum dot effect can be used as the material of the light emitting layer 17.

In the present embodiment, the light emitting layer 17 is a coating film formed by coating film formation using ink.

(8) Electron transport layer The electron transport layer 18 has a function of transporting electrons from the counter electrode 20 to the light emitting layer 17. The electron transport layer 18 is made of an organic material having high electron transportability.

Examples of the organic material used for the electron transport layer 18 include π-electron low-molecular-weight organic materials such as an oxadiazole derivative (OXD), a triazole derivative (TAZ), and a phenanthroline derivative (BCP, Bphen).

(9) Electron Injection Layer The electron injection layer 19 is provided on the electron transport layer 18 in common with a plurality of pixels, and has a function of promoting the injection of electrons from the counter electrode 20 into the light emitting layer 17.

The electron injection layer 19 is formed by, for example, doping an organic material having electron transportability with a metal material for improving electron injection property. Here, the dope means to disperse the metal atoms or metal ions of the metal material substantially evenly in the organic material, and specifically, to form a single phase containing the organic material and a trace amount of the metal material. Point to that. In this embodiment, Ba is selected.

The electron injection layer 19 is formed by, for example, forming a film of a material such as an oxadiazole derivative, a triazole derivative, or a phenanthroline derivative and a metal material in common to a plurality of pixels by a co-evaporation method.

(10) Opposite electrode The counter electrode 20 is formed on the electron injection layer 19 in common with a plurality of pixels, and functions as a cathode.

In the present embodiment, the counter electrode 20 has both translucency and conductivity, and includes at least one of a metal layer formed of a metal material and a metal oxide layer formed of a metal oxide. There is. The film thickness of the metal layer is about 1 nm to 50 nm in order to ensure the translucency. Examples of the material of the metal layer include a silver alloy containing Ag and Ag as main components, and an Al alloy containing Al and Al as main components.

The counter electrode 20 may be composed of the metal layer alone or the metal oxide layer alone, but may have a laminated structure in which the metal oxide layer is laminated on the metal layer, or the metal layer may be formed on the metal oxide layer. It may be a laminated structure in which it is laminated.

(11) Sealing layer A sealing layer 21 is provided on the counter electrode 20. The sealing layer 21 prevents impurities (water, oxygen) from invading the counter electrode 20, the electron injection layer 19, the electron transport layer 18, the light emitting layer 17, etc. from the opposite side of the substrate 11, and these layers due to impurities. Has a function of suppressing deterioration of. The sealing layer 21 is formed by using a translucent material such as silicon nitride (SiN) or silicon oxynitride (SiON). Further, a sealing resin layer made of a resin material such as an acrylic resin or an epoxy resin may be provided on a layer formed by using a material such as silicon nitride (SiN) or silicon oxynitride (SiON).

In the present embodiment, since the organic EL display panel 10 is a top emission type, the sealing layer 21 needs to be formed of a light-transmitting material.

(12) Others Although not shown in FIG. 3, a color filter or a deflection sheet using a glass substrate as a base material may be attached to the sealing layer 21 via an adhesive. By laminating these, the hole transport layer 16, the light emitting layer 17, the electron transport layer 18, and the electron injection layer 19 can be further protected from external moisture, air, and the like.

<Coating film formation process of light emitting layer and generation of color mixing>
Hereinafter, the coating film forming step of the light emitting layer 17 and the color mixing that may occur in the coating film forming step will be described in detail.

(1) Coating without color mixing FIG. 4 is a schematic cross-sectional view of the organic EL display panel 10 in the coating film formation step of the light emitting layer, and corresponds to the AA cross section of FIG. Here, for simplification of the description, it is assumed that the light emitting colors are two colors, the light emitting layer to be coated first is the light emitting layer 17X, and the light emitting layer to be coated later is the light emitting layer 17Y.

In the light emitting layer coating step, first, ink is applied to the opening 14aX from the nozzle 3011X of the inkjet head 301X (FIG. 4A) to form the light emitting layer material ink layer 170X (FIG. 4B). Next, ink is applied to the opening 14aY from the nozzle 3011Y of the inkjet head 301Y (FIG. 4 (b)) to form the light emitting layer material ink layer 170Y (FIG. 4 (c)). Then, the light emitting layer material ink layers 170X and 170Y are dried to form a light emitting layer 17X and 170Y (FIG. 4 (d)).

(2) Color mixing due to deviation of the coating position of the first color FIG. 5 is a schematic cross-sectional view of the organic EL display panel 10 in the coating film forming step of the light emitting layer, and corresponds to the AA cross section of FIG. Here, FIG. 5 shows a state in which ink is dropped on the partition wall 14 in the first color coating step.

As shown in FIG. 5A, in this case, when ink is applied to the opening 14aX from the nozzle 3011X of the inkjet head 301X, a part of the ink is also applied on the partition wall 14. Then, as shown in FIG. 5B, when the light emitting layer material ink layer 170X is formed, the ink on the partition wall 14 is connected to the light emitting layer material ink layer 170X, so that the ink flow path (bridge) on the partition wall 14 is formed. ) Is formed, and ink also flows into the adjacent opening 14aY. In this state, when ink is applied to the opening 14aY from the nozzle 3011Y of the inkjet head 301Y to form the light emitting layer material ink layer 170Y, the ink is discharged between the opening 14aX and the opening 14aY via the bridge on the partition wall 14. Will be exchanged. Therefore, as shown in FIG. 5C, a light emitting layer material ink layer 170XY in a mixed color state is formed in both the opening 14aX and the opening 14aY, and when this is dried, as shown in FIG. 5D. , The light emitting layer 17XY in a mixed color state is formed. When this state is viewed in a plan view, as shown in the schematic plan view of FIG. 9, a color mixing region is formed in a wide range of two adjacent openings 14aX and 14aY centering on the ink dropped on the partition wall 14. That is, a large-scale color mixing (bridge color mixing) occurs in both the opening 14aX and the opening 14aY.

On the other hand, FIG. 6 is a schematic cross-sectional view of the organic EL display panel 10 in the coating film forming step of the light emitting layer, and corresponds to the AA cross section of FIG. Here, FIG. 5 shows a state in which the material ink of the light emitting layer 17X is dropped on the opening 14aY in the first color coating step.

As shown in FIG. 6A, in this case, when ink is applied to the opening 14aX from the nozzle 3011X of the inkjet head 301X, a part of the ink is also applied to the opening 14aY. Then, as shown in FIG. 6B, when the light emitting layer material ink layer 170X is formed, a minute light emitting layer material ink layer 170X is also formed in the opening 14aY. In this state, when ink is applied to the opening 14aY from the nozzle 3011Y of the inkjet head 301Y to form the light emitting layer material ink layer 170Y, as shown in FIG. 6C, the material of the light emitting layer 17Y is formed in the opening 14aY. A small amount of the material ink of the light emitting layer 17X is mixed with the ink, and the light emitting layer material ink layer 170Y'is formed in the opening 14aY. On the other hand, even if the light emitting layer material ink layer 170Y'is formed, the opening 14aX is not affected by the color mixing. Therefore, as shown in FIG. 6D, after the ink is dried, a light emitting layer 17Y'in which a small amount of the material of the light emitting layer 17X is mixed is formed in the opening 14aY, while a normal light emitting layer is formed in the opening 14aX. 17X is formed. When this state is viewed in a plan view, as shown in the schematic plan view of FIG. 10, a color mixing region is generated only in a narrow range around the position where the material ink of the light emitting layer 17X is dropped in the opening 14aY. That is, minute color mixing occurs only at the opening 14aY.

(3) Color Mixing Due to Misalignment of Coating Position of Second Color FIG. 7 is a schematic cross-sectional view of the organic EL display panel 10 in the coating film forming step of the light emitting layer, and corresponds to the AA cross section of FIG. Here, FIG. 7 shows a state in which ink is dropped on the partition wall 14 in the second color coating step. Here, FIG. 7 shows a state in which ink is dropped on the partition wall 14 in the second color coating step.

First, as shown in FIG. 7A, ink is applied to the opening 14aX from the nozzle 3011X of the inkjet head 301X to form the light emitting layer material ink layer 170X. Next, as shown in FIG. 7B, ink is applied to the opening 14aY from the nozzle 3011Y of the inkjet head 301Y, and at this time, a part of the ink is also applied on the partition wall 14. Then, as shown in FIG. 7C, the ink on the partition wall 14 becomes a flow path (bridge) that bridges the light emitting layer material ink layer 170X and the light emitting layer material ink layer 170Y to be formed in the opening 14aY. In some cases, ink may be exchanged between the opening 14aX and the opening 14aY via a bridge on the partition wall 14. In this case, a light emitting layer material ink layer 170XY in a mixed color state is formed in both the opening 14aX and the opening 14aY, and when this is dried, a light emitting layer 17XY in a mixed color state is formed as shown in FIG. 7 (d). Will be done. When this state is viewed in a plan view, as shown in the schematic plan view of FIG. 9, a color mixing region is formed in a wide range of two adjacent openings 14aX and 14aY centering on the ink dropped on the partition wall 14. That is, a large-scale color mixing (bridge color mixing) occurs in both the opening 14aX and the opening 14aY.

FIG. 8 is a schematic cross-sectional view of the organic EL display panel 10 in the coating film forming step of the light emitting layer, and corresponds to the AA cross section of FIG. Here, FIG. 8 shows a state in which ink is dropped on the partition wall 14 in the second color coating step. Here, FIG. 8 shows a state in which ink is dropped into the opening 14aX in the second color coating step.

First, as shown in FIG. 8A, ink is applied to the opening 14aX from the nozzle 3011X of the inkjet head 301X to form the light emitting layer material ink layer 170X. Next, as shown in FIG. 8B, ink is applied to the opening 14aY from the nozzle 3011Y of the inkjet head 301Y, and at this time, a part of the ink is also applied to the inside of the opening 14aX. At this time, since the amount of the light emitting layer material ink layer 170X is often close to the maximum amount that can be accommodated in the opening 14aX, not only color mixing occurs in the opening 14aX but also as shown in FIG. 8C. Ink often overflows from the opening 14aX beyond the partition wall 14 to the adjacent opening 14aY. As a result, the ink that overflows over the partition wall 14 becomes a flow path (bridge) that bridges the light emitting layer material ink layer 170X and the light emitting layer material ink layer 170Y that is intended to be formed in the opening 14aY, and the bridge on the partition wall 14 is formed. Ink is exchanged between the opening 14aX and the opening 14aY through the ink. Therefore, the light emitting layer material ink layer 170XY in the mixed color state is formed in both the opening 14aX and the opening 14aY, and when this is dried, the light emitting layer 17XY in the mixed color state is formed as shown in FIG. 8D. The Rukoto. When this state is viewed in a plan view, as shown in the schematic plan view of FIG. 9, a mixed color region is formed in a wide range of two adjacent openings 14aX and 14aY centering on the ink overflowing portion generated on the partition wall 14. .. That is, a large-scale color mixing (bridge color mixing) occurs in both the opening 14aX and the opening 14aY. Even when bridge color mixing occurs, the ink may not remain on the partition wall 14 to the extent that it can be observed by the visual inspection device after the ink has dried.

(3) Conditions for Occurrence of Bridge Color Mixing and Trace Color Mixing As described above, when ink is applied on the partition wall 14, large-scale color mixing (bridge color mixing) occurs. The reason is that, as described above, the ink on the partition wall 14 functions as an ink flow path that bridges the ink layers in the two adjacent openings, so that the ink is exchanged between the ink layers in the two adjacent openings. This is because a large-scale inflow and outflow of ink occurs at any of the openings.

On the other hand, when a small amount of ink is dropped on the opening 14a that is not intended to be applied, the conditions differ depending on whether or not the ink has already been applied to the unintended opening 14a. When the ink is not applied to the opening 14a, that is, when a small amount of ink is dropped on the opening 14a which is not intended in the first application of the first color, the unintended opening is as described above. Since the ink is only mixed at 14a, only a small amount of color mixing occurs at the unintended opening 14a. On the other hand, when the ink has already been applied to the opening 14a, that is, when a small amount of ink is erroneously dropped into the opening to which the ink has already been applied in the application of the second and subsequent colors, the above-mentioned case has been described. As described above, ink may overflow from the opening 14a and bridge color mixing may occur.

That is, when a small amount of ink is erroneously dropped on the opening 14a, the situation differs depending on which ink among the plurality of inks the abnormal coating occurs, and in the case of two colors, the situation is as follows.

（４）混色の検出
上述したように、ブリッジ混色では、隣接する２つの開口部においてインクの混合が広範囲で起きるため、発光層１７の外観に異常が発生することが多く、また、インクの流路となるブリッジの痕跡が隔壁１４上に残存することもある。したがって、ブリッジ混色が発生したか否かは、発光層１７の成膜後に、発光層１７および隔壁１４の外観を検査することで、比較的容易に検出できる。一方で、微量混色では、開口部１４ａからインクが溢出しない程度に意図しないインクが混じる程度の混色であるので、外観上検出できる程度に発光層１７の変色が起きるとは限らず、また、混色した開口部１４ａ以外の場所には混色の痕跡が残らない。したがって、微量混色が発生したか否かは、発光層１７の成膜後に、発光層１７および隔壁１４の外観を検査しても発見が困難であり、通電して発光させることで、初めて発覚する場合が多い。

(4) Detection of Color Mixing As described above, in bridge color mixing, ink mixing occurs in a wide range at two adjacent openings, so that the appearance of the light emitting layer 17 often becomes abnormal, and ink flow occurs. Traces of the bridge that serves as a road may remain on the partition wall 14. Therefore, whether or not bridge color mixing has occurred can be detected relatively easily by inspecting the appearance of the light emitting layer 17 and the partition wall 14 after the film formation of the light emitting layer 17. On the other hand, in the case of a small amount of color mixing, the color mixing is such that unintended ink is mixed to the extent that the ink does not overflow from the opening 14a. No trace of color mixing remains in places other than the opened opening 14a. Therefore, it is difficult to find out whether or not a slight amount of color mixing has occurred even if the appearances of the light emitting layer 17 and the partition wall 14 are inspected after the film formation of the light emitting layer 17, and it is only discovered by energizing and emitting light. In many cases.

On the other hand, in a slight amount of color mixing, the emission color abnormality does not always occur, and there is a case where the emission color has no problem and can be used as a normal pixel. The emission color of the pixel in which a trace amount of color mixing occurs depends on the combination of the original emission color and the emission color of the emission material mixed in a trace amount. In the self-luminous element, excitons are generated inside the light emitting layer 17 by recombination of electrons and holes injected into the light emitting layer 17, and the energy of excitons of the light emitting material is converted into the energy of photons to emit light. Occurs. That is, the excitons of the light emitting material and the emitted photons have a one-to-one correspondence, and their energy amounts are also the same. Therefore, the energy of excitons in the light emitting material increases as the wavelength of the emitted light (wavelength in vacuum) becomes shorter, and decreases as the wavelength of the emitted light becomes longer. Therefore, when there are two or more types of light emitting materials, exciters of each light emitting material can be generated, but the excitors of the light emitting material having a long emission wavelength (hereinafter referred to as "long wavelength light emitting material") emit light. It is easier to generate than the exciter of a light emitting material with a short wavelength (hereinafter referred to as "short wavelength light emitting material"), and the energy transition from the exciter of the short wavelength light emitting material to the exciter of the long wavelength light emitting material is likely to occur. .. Therefore, when a small amount of the long-wavelength light-emitting material is mixed with the short-wavelength light-emitting material, the long-wavelength light-emitting material emits light with a significant intensity, and the light emission of the short-wavelength light-emitting material is extinguished by the long-wavelength light-emitting material. The luminescent color of the material is mixed to cause a chromaticity shift, or the luminescence of the long wavelength luminescent material becomes dominant. On the other hand, when a small amount of the short wavelength light emitting material is mixed in the long wavelength light emitting wavelength, the light emission of the short wavelength light emitting material is quenched by the long wavelength light emitting material, so that the short wavelength light emitting material hardly emits light, and the influence of color mixing is affected. It rarely occurs.

Therefore, for trace color mixing, the emission color of the ink applied first is the first color, the emission wavelength (vacuum wavelength) is λ ₁ , the emission color of the ink applied later is the second color, and the emission wavelength (vacuum wavelength). When is λ ₂ , the emission color satisfies the following relationship.

つまり、第１色の波長（真空波長）が第２色の波長（真空波長）より短い場合、第１色のインク、第２色のインクの順に塗布を行った場合の副画素の発光色は、微量混色（開口部内への意図しないインク滴下）の有無によって以下のように変わる。

That is, when the wavelength of the first color (vacuum wavelength) is shorter than the wavelength of the second color (vacuum wavelength), the emission color of the sub-pixel when the first color ink and the second color ink are applied in this order is , It changes as follows depending on the presence or absence of a slight amount of color mixing (unintentional dripping of ink into the opening).

表３に示すように、第２色のインクが塗布されるべき領域で微量混色（第１色のインクの混入）が起きた場合は、第２色に発色する。つまり、微量混色が起きても発光色の異常は生じない。すなわち、第１色の波長（真空波長）が第２色の波長（真空波長）より短い場合において、第１色のインク、第２色のインクの順に塗布を行った場合の副画素の発光色は、ブリッジ混色が起きた場合のみとなる。

As shown in Table 3, when a slight amount of color mixing (mixing of the first color ink) occurs in the region where the second color ink should be applied, the second color is developed. That is, even if a slight amount of color mixing occurs, the emission color does not become abnormal. That is, when the wavelength of the first color (vacuum wavelength) is shorter than the wavelength of the second color (vacuum wavelength), the emission color of the sub-pixel when the first color ink and the second color ink are applied in this order. Is only when bridge color mixing occurs.

On the other hand, when the wavelength of the first color (vacuum wavelength) is longer than the wavelength of the second color (vacuum wavelength), the emission color of the sub-pixel when the first color ink and the second color ink are applied in this order is , It changes as follows depending on the presence or absence of a slight amount of color mixing (unintentional dripping of ink into the opening).

表４に示すように、第２色のインクが塗布されるべき領域で微量混色（第１色のインクの混入）が起きた場合は、第１色に発色する（または、第１色側に色ずれする）。つまり、微量混色が起きると、発光色の異常が生じる。すなわち、第１色の波長（真空波長）が第２色の波長（真空波長）より長い場合において、第１色のインク、第２色のインクの順に塗布を行った場合の副画素の発光色異常は、ブリッジ混色が起きた場合のみならず、微量混色によっても発生する。

As shown in Table 4, when a slight amount of color mixing (mixing of the first color ink) occurs in the area where the second color ink should be applied, the color is developed in the first color (or on the first color side). Color shift). That is, when a slight amount of color mixing occurs, an abnormality in the emitted color occurs. That is, when the wavelength of the first color (vacuum wavelength) is longer than the wavelength of the second color (vacuum wavelength), the emission color of the sub-pixel when the first color ink and the second color ink are applied in this order. Abnormalities occur not only when bridge color mixing occurs, but also when a small amount of color mixing occurs.

(5) Summary As described above, when the light emitting layer is formed by the coating method, the ink containing the short wavelength light emitting material is first applied, and then the ink containing the long wavelength light emitting material is applied to shorten the length. Even if a slight amount of color mixing occurs due to abnormal application of ink containing a wavelength emitting material, the mixed color pixels emit light in the intended color. That is, since the trace color mixing does not cause the emission color abnormality, the trace color mixing that is difficult to detect does not cause the dysplasia. Therefore, it is possible to limit the dysplasia due to the coating process to only the bridge color mixing that is easy to detect, and it is possible to avoid the situation where the dysplasia that is difficult to detect is overlooked.

More specifically, the case of a three-color light emitting panel having light emitting colors of red, green, and blue will be described. When blue ink, green ink, and red ink are applied in this order as disclosed in the present disclosure, the light emission abnormalities due to color mixing are as follows.

すなわち、発光色異常が発生するのは、ブリッジ混色が発生した場合のみであり、青色インクが緑色発光層や赤色発光層に微量混色した場合、緑色インクが赤色発光層に微量混色した場合は、いずれも発光色異常が起きない。したがって、塗布工程が原因で発生した不良パネルは、検出の容易なブリッジ混色が発生したパネルのみである。

That is, the emission color abnormality occurs only when the bridge color mixture occurs, and when the blue ink is slightly mixed in the green light emitting layer or the red light emitting layer, or when the green ink is slightly mixed in the red light emitting layer, the emission color abnormality occurs. No abnormal emission color occurs in either case. Therefore, the only defective panel generated due to the coating process is the panel in which the bridge color mixing that is easy to detect occurs.

On the other hand, when the red ink, the green ink, and the blue ink are applied in this order, the light emission abnormality due to the color mixing is as follows.

すなわち、発光色異常が発生するのは、ブリッジ混色が発生した場合に加えて、赤色インクが緑色発光層や青色発光層に微量混色した場合、緑色インクが青色発光層に微量混色した場合も含まれる。したがって、検出の容易なブリッジ混色が発生したパネルのみならず、通電による発光試験を行わなければ発見が困難な微量混色が発生したパネルも形成不良パネルとなり、歩留まりが低下する要因となる。すなわち、実施の形態に係る塗布順序であれば、微量混色がパネルの不良原因とならないため、微量混色が外観検査で検出できなくても歩留まり悪化を抑止することができる。

That is, the emission color abnormality occurs not only when the bridge color mixing occurs, but also when the red ink is slightly mixed in the green light emitting layer and the blue light emitting layer, and when the green ink is slightly mixed in the blue light emitting layer. Is done. Therefore, not only the panel in which the bridge color mixture is easily detected but also the panel in which the trace color mixture is generated, which is difficult to detect without the light emission test by energization, becomes a poorly formed panel, which causes a decrease in yield. That is, in the coating order according to the embodiment, since the trace color mixing does not cause a defect in the panel, it is possible to suppress the deterioration of the yield even if the trace color mixing cannot be detected by the visual inspection.

<Manufacturing method of self-luminous panel>
Hereinafter, a method for manufacturing the organic EL display panel 10 as a self-luminous panel will be described with reference to the drawings.

FIG. 11 is a flowchart showing a manufacturing method of the organic EL display panel 10. 12 to 15 are schematic cross-sectional views showing a state in each step in the manufacture of the organic EL display panel 10, and correspond to the AA cross section of FIG.

(1) Formation of Substrate 11 First, the TFT layer 112 is formed on the substrate 111 to form the substrate 11 (step S10, FIG. 12A). The TFT layer 112 can be formed by a known method for manufacturing a TFT.

Next, the interlayer insulating layer 12 is formed on the substrate 11 (S20, FIG. 12B). Specifically, a resin material having a constant fluidity is applied, for example, by a die coating method so as to fill the unevenness on the substrate 11 by the TFT layer 112 along the upper surface of the substrate 11. As a result, the upper surface of the interlayer insulating layer 12 has a flattened shape along the upper surface of the base material 111.

A contact hole is formed in the interlayer insulating layer 12 by performing a dry etching method on a portion of the TFT element, for example, on the source electrode. The contact hole is formed by patterning or the like so that the surface of the source electrode is exposed at the bottom thereof.

Next, a connection electrode layer is formed along the inner wall of the contact hole. A part of the upper portion of the connection electrode layer is arranged on the interlayer insulating layer 12. For the formation of the connection electrode layer, for example, a sputtering method can be used, and after forming a metal film, patterning may be performed using a photolithography method and a wet etching method.

(2) Formation of Pixel Electrode 13 Next, the pixel electrode 13 is formed on the interlayer insulating layer 12.

First, a pixel electrode material layer 130 made of the material of the pixel electrode 13 is formed on the interlayer insulating layer 12 by, for example, a vacuum vapor deposition method, a sputtering method, or the like (step S31, FIG. 12C). Next, the pixel electrode material layer 130 is patterned by etching to form a plurality of pixel electrodes 13 partitioned by sub-pixels (step S32, FIG. 12D).

(3) Formation of partition wall 14 Next, the partition wall 14 is formed. First, a solution prepared by dissolving a phenol resin, which is a partition resin, in a solvent (for example, a mixed solvent of ethyl lactate and GBL) is uniformly applied onto the pixel electrode 13 and the interlayer insulating layer 12 by a spin coating method or the like. Then, the partition material layer 140 is formed (step S41, FIG. 12 (e)). Then, the partition wall material layer 140 is subjected to pattern exposure and development to form the partition wall 14 (step S42, FIG. 13A).

(4) Formation of Hole Injection Layer 15 Next, the hole injection layer 15 is formed (step S50, FIG. 13B). Specifically, the hole injection layer forming ink containing the constituent material of the hole injection layer 15 as a solute is ejected from the nozzle 3011 of the printing apparatus 301 into the opening 14a defined by the partition wall 14. After being applied onto the pixel electrode 13 in 14a, it is dried to form the hole injection layer 15.

The formation of the hole injection layer 15 is not limited to the coating method, and may be formed by a vapor deposition method or sputtering.

(5) Formation of Hole Transport Layer 16 Next, the hole transport layer 16 is formed (step S60, FIG. 13 (c)). Specifically, the hole transport layer forming ink containing the constituent material of the hole transport layer 16 as a solute is ejected from the nozzle 3011 of the printing apparatus 301 into the opening 14a defined by the partition wall 14. After coating on the hole injection layer 15 in 14a, it is dried to form the hole transport layer 16.

The formation of the hole transport layer 16 is not limited to the coating method, and may be formed by a vapor deposition method or sputtering.

(6) Formation of Light Emitting Layer 17 Next, an ink for forming a light emitting layer containing a constituent material of the light emitting layer 17 as a solute is applied to the opening 14a defined by the partition wall 14 from an ink containing a light emitting material having a short emission wavelength. In order, the ink is discharged from the nozzle of the printing apparatus, coated on the hole transport layer 16 in the opening 14a, and then dried to form the light emitting layer 17 (step S70, FIG. 14A). Details have already been described and will be omitted.

(7) Appearance inspection of the light emitting layer 17 Next, an appearance inspection of the light emitting layer 17 formed in the opening 14a and the partition wall 14 defining the opening 14a is performed (step S210). The visual inspection is, for example, an visual inspection, for example, an image of the light emitting layer 17 and the partition wall 14 adjacent to the light emitting layer 17, the color and shape of the light emitting layer 17, the presence or absence of foreign matter on the partition wall 14, and particularly the light emitting layer 17. This is done by detecting the presence or absence of dried matter in the material ink. If a formation abnormality such as color mixing is found in the visual inspection, the organic EL display panel may be discarded as a defective product without performing the subsequent manufacturing process. In addition, if a formation abnormality such as color mixing is found in the visual inspection, the cause of the inspection of the coating device is investigated, and the process of forming the light emitting layer 17 on the next organic EL display panel 10 is not performed until the cause is investigated. May be good.

(8) Formation of Electron Transport Layer 18 Next, an electron transport layer 18 is formed on the light emitting layer 17 and the partition wall 14 (step S80, FIG. 14 (b)). The electron transport layer 18 is formed, for example, by forming an electron transportable organic material in common with each subpixel by a vapor deposition method.

(9) Formation of Electron Injection Layer 19 Next, an electron injection layer 19 is formed on the electron transport layer 18 (step S90, FIG. 14 (c)). The electron injection layer 19 is formed, for example, by forming an electron-transporting organic material and a dope metal in common on each subpixel by a co-evaporation method.

(10) Formation of counter electrode 20 Next, the counter electrode 20 is formed on the electron injection layer 19 (step S100, FIG. 15 (a)). The counter electrode 20 is formed by forming a film of ITO, IZO, silver, aluminum or the like by a sputtering method or a vacuum vapor deposition method.

(11) Formation of Sealing Layer 21 Next, the sealing layer 21 is formed on the counter electrode 20 (step S110, FIG. 15B). The sealing layer 21 can be formed by forming a film of SiON, SiN, or the like by a sputtering method, a CVD method, or the like.

As a result, the organic EL display panel 10 which is a self-luminous panel is completed.

(12) Emission Color Inspection of Organic EL Display Panel 10 Next, the emission color inspection of the organic EL display panel 10 formed up to step S110 is performed (step S210). In the emission color inspection, for example, the organic EL display panel 10 is electrically connected to the drive control circuit unit 200, and the drive control circuit unit 200 transmits a light emission command to each light emitting element 2 of the organic EL display panel 10 to emit light. This is performed by detecting the emission intensity and peak wavelength of each element 2.

When an abnormality is found in the emission color inspection, for example, when the number of light emitting elements in which the emission color abnormality exists is small, a drive control circuit is used so as not to drive the light emitting element (so that it is a dead point). The setting may be made in unit 200, or when the number of light emitting elements having an emission color abnormality is large, the organic EL display panel may be discarded as a defective product.

≪Modification example≫
As described above, as one aspect of the present disclosure, a method for manufacturing an organic EL display panel as a self-luminous panel and an organic EL element has been described. It is not limited. Hereinafter, a modified example which is another embodiment of the present invention will be described.

(1) In the above embodiment, it is assumed that the pixel electrode is an anode, the counter electrode is a cathode, and the top emission type organic EL element. However, for example, the pixel electrode may be a cathode and the counter electrode may be an anode. Further, for example, it may be a bottom emission type organic EL element. In this case, the pixel electrode is formed of a light-transmitting conductive material, and the counter electrode is formed of a light-reflecting conductive material. Further, at least the portion of the substrate 11 that is layered under the pixel electrode has light transmission.

The self-luminous element is not limited to the organic EL element, and may be another element such as a QLED.

(2) In the above embodiment, it is assumed that the hole injection layer 15, the hole transport layer 16, and the light emitting layer 17 are all formed in the coating step. However, the light emitting layer 17 may be formed by the coating steps in the order according to the embodiment, and the other layers may be formed by a vapor deposition method, a sputtering method, or the like. Alternatively, for example, any one or more of the electron transport layer 18 and the electron injection layer 19 may be formed in the coating step.

Further, one light emitting element may be configured to include a plurality of light emitting layers. In this case, it is sufficient that two adjacent light emitting elements straddling the partition wall have a light emitting layer as a coating film having different light emitting colors from each other, and for example, further having a light emitting layer as a common layer formed by a vapor deposition method. May be.

(3) In the above embodiment, the organic EL element 2 is configured to have an electron transport layer 18, an electron injection layer 19, a hole injection layer 15, and a hole transport layer 16, but the present invention is limited to this. No. For example, it may be an organic EL element having no electron transport layer 18 or an organic EL element having no hole transport layer 16. Further, for example, instead of the hole injection layer 15 and the hole transport layer 16, a single hole injection transport layer may be provided. Further, for example, an intermediate layer made of any of an alkali metal, an alkaline earth metal, a rare earth, or a fluoride thereof may be provided between the light emitting layer 17 and the electron transport layer 18.

Further, the emission color of the light emitting layer 17 is not limited to two colors or three colors of red, green, and blue, and may be four or more colors including yellow and purple, and the combination of the three colors is limited to the above. No.

(4) In the above embodiment, the appearance inspection of the light emitting layer is performed immediately after the film formation of the light emitting layer, but the present invention is not limited to this. For example, the visual inspection of the light emitting layer may be performed after the film formation of the sealing layer. However, from the viewpoint of early detection of bridge color mixing in the film forming step of the light emitting layer, it is preferable that the appearance inspection of the light emitting layer is performed earlier after the film forming step of the light emitting layer.

(5) In the above embodiment, the ink is a solution containing a functional material as a solute, but the ink is not limited to this, and is a colloidal solution or a suspension in which the functional material is dispersed in a mixed solvent. You may.

(6) As long as high-definition ink can be applied through the nozzle, not only the inkjet device according to the above embodiment, but also a dispenser-type coating device that continuously ejects ink onto the substrate can be used. May be good.

(7) In the above embodiment, the line bank method in which partition walls are formed in a row is described, but the present invention is not limited to this. It suffices that one or more of the functional layers are formed by a coating method, and two adjacent light emitting elements straddling the partition wall are provided with a light emitting layer as a coating film having different emission colors from each other. It may have a pixel bank structure in which each pixel is surrounded by a partition wall, or a honeycomb structure in which hexagonal sub-pixels are arranged in a staggered pattern, in which the partition wall extends on a broken line.

The present invention is optimal as a method for manufacturing a self-luminous panel in which a light emitting layer is formed by a coating method.

1 Display device 10 Self-luminous panel (organic EL display panel)
2 Light emitting element (organic EL element)
11 Substrate 12 Interlayer insulation layer 13 Pixel electrode 14 Partition wall 14a Opening 15 Hole injection layer 16 Hole transport layer 17 Light emitting layer 18 Electron transport layer 19 Electron injection layer 20 Opposite electrode 21 Sealing layer 200 Drive control circuit unit 210 Drive circuit 220 control circuit

Claims (8)

Prepare the board,
Pixel electrodes are formed in a matrix on the substrate,
A plurality of partition walls extending in the column direction and partitioning the pixel electrodes in the row direction are formed.
A first ink containing a first light emitting material is applied to the first gap among the gaps between two partition walls adjacent to each other in the row direction to form a first light emitting layer.
After the application of the first ink, a second ink containing a second light emitting material having a longer emission wavelength than the first light emitting material is applied to the second gap adjacent to the first gap in the row direction. Forming a second light emitting layer,
A counter electrode is formed above the first light emitting layer and the second light emitting layer.
Each of a first light emitting element including the pixel electrode, the first light emitting layer, and the counter electrode, and a second light emitting element including the pixel electrode, the second light emitting layer, and the counter electrode. A method for manufacturing a self-luminous panel, which comprises performing an emission color inspection by turning on the light and inspecting the emission color. In the emission color inspection, if the emission color of the light emitting element formed in the second gap is the same as the emission color of the second element, is the first ink erroneously mixed in the second gap? The method for manufacturing a self-luminous panel according to claim 1, wherein the light emitting element formed in the second gap is determined to be a normal second light emitting element regardless of whether or not the second light emitting element is formed. After the formation of the second light emitting layer, the appearance of each of the first light emitting layer and the second light emitting layer is inspected, and the first ink is placed between the first gap and the second gap. When it is confirmed that the second ink is mixed, a visual inspection for determining that there is an abnormality in the first light emitting layer in the first gap and the second light emitting layer in the second gap is performed. The method for manufacturing a self-luminous panel according to claim 1 or 2, further comprising. The third aspect of the present invention, wherein the self-luminous panel is discontinued when it is determined in the visual inspection that there is an abnormality in the first light emitting layer and / or the second light emitting layer. Manufacturing method of self-luminous panel. A self-luminous panel comprising a light emitting element that emits light in a first color in a display region on a substrate and a light emitting element that emits light in a second color having a wavelength longer than the wavelength of the first color.
The first light emitting element that emits light in the first color includes a first light emitting layer and a pair of electrodes facing each other via the first light emitting layer.
The second light emitting element that emits light in the second color includes a second light emitting layer and a pair of electrodes facing each other via the second light emitting layer.
The first light emitting layer and the second light emitting layer are separated by a partition wall.
The first light emitting layer is a coating film and contains the first light emitting material.
The second light emitting layer is a coating film, and is a self-luminous panel characterized by containing a second light emitting material and a trace amount of the first light emitting material. A third light emitting element including a third light emitting layer and a pair of electrodes facing each other via the third light emitting layer is further included.
The third light emitting layer is a coating film, which contains the second light emitting material and does not contain the first light emitting material.
The self-luminous panel according to claim 5, wherein the third light emitting element emits light in the second color. The partition wall extends in the row direction and
A plurality of the first light emitting elements are arranged in a row in the gap between the partition wall and the second partition wall extending in the row direction.
The self-luminous panel according to claim 5 or 6, wherein the second light emitting element is arranged in a gap between the partition wall and a third partition wall extending in the row direction. The self-luminous panel according to any one of claims 5 to 7, wherein both the first light emitting material and the second light emitting material are organic materials that emit light by electroluminescence.

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