Method for manufacturing display device

Abstract

This method for manufacturing a display device comprises a light-emitting element layer formation step for forming a light-emitting element layer in which a plurality of first electrodes, a plurality of light-emitting functional layers, and a second electrode used in common are sequentially laminated. The step involves: aligning the position of a base mother substrate using an alignment mark (M) formed in a TFT layer formation step; discharging and applying ink so as to overlap the alignment mark (M); inspecting a thus applied coating film (J) and thereafter discharging and applying ink while moving an application head (110); and forming a plurality of light-emitting functional layers in a display region corresponding to the alignment mark (M) by using a thus applied coating film (1w).

Description

Manufacturing method of display device

[0001] The present invention relates to a manufacturing method of a display device.

[0002] In recent years, as a display device replacing a liquid crystal display device, particularly, a display device including an organic light emitting diode (hereinafter also referred to as "OLED"), an inorganic light emitting diode, and a quantum dot light emitting diode (hereinafter also referred to as "QLED") has attracted high attention because it can achieve low power consumption, thinning, and high image quality. This display device including QLED includes, for example, a base substrate, a thin film transistor (hereinafter also referred to as "TFT") layer provided on the base substrate, a QLED element layer provided on the TFT layer, and a sealing film provided on the QLED element layer. Here, the QLED element constituting the QLED element layer includes, for example, a first electrode provided on the TFT layer, a QLED layer provided as a light emitting functional layer on the first electrode, and a second electrode provided on the QLED layer. And the QLED layer includes, for example, a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer, and is formed by a vacuum evaporation method, an inkjet method, a slit coating method, or the like.

[0003] For example, Patent Document 1 discloses a manufacturing method of a display device having a discharge step of discharging ink containing a color conversion material from a discharge head toward a position where a pixel is formed on a substrate, a light irradiation step of irradiating the ink discharged from the discharge head with light having a predetermined wavelength from a light source, a light intensity measurement step of measuring the intensity of the color-converted light emitted from the ink irradiated with the light having the predetermined wavelength, and a control step of controlling subsequent discharge toward the position where the pixel is formed based on the measurement result of the light intensity measurement step.

[0004] Japanese Patent Application Laid-Open No. 2020-194018

[0005] Incidentally, in QLED display devices, there is a growing trend to form the hole injection layer and electron transport layer of the QLED layer (light-emitting functional layer) using an inkjet method by applying ink containing nanoparticles. In this case, while defects in the formation of the light-emitting functional layer can be detected early by inspecting the coated film that constitutes the light-emitting functional layer, this requires equipment such as a CCD (charge-coupled device) camera, which increases manufacturing costs, so there is room for improvement.

[0006] This invention has been made in view of the above, and its purpose is to verify the quality of the light-emitting functional layer formed by the inkjet method at low cost.

[0007] To achieve the above objective, the present invention provides a method for manufacturing a display device, comprising: a thin-film transistor layer formation step of forming thin-film transistor layers in each of the multiple display areas defined on a base substrate; and a light-emitting element layer formation step of forming a light-emitting element layer on the thin-film transistor layer, in which a plurality of first electrodes, a plurality of light-emitting functional layers, and a common second electrode are sequentially stacked corresponding to a plurality of subpixels constituting the display area, wherein the light-emitting element layer formation step involves moving a coating head having a plurality of nozzles and ejecting ink from the plurality of nozzles to form the plurality of light-emitting functional layers by an inkjet method, wherein the thin-film transistor layer formation step involves forming alignment marks on the outside of each of the plurality of display areas on the base substrate, and the light-emitting functional layer formation step involves using the alignment marks to align the base substrate, ejecting and applying the ink so as to overlap the alignment marks, inspecting the applied coating film, then moving the coating head and ejecting and applying the ink to form the plurality of light-emitting functional layers on the display areas corresponding to the alignment marks.

[0008] Furthermore, the present invention relates to a method for manufacturing a display device, comprising: a thin-film transistor layer formation step of forming thin-film transistor layers in each of the multiple display areas on a base substrate having a plurality of defined display areas; and a light-emitting element layer formation step of forming a light-emitting element layer on the thin-film transistor layer, in which a plurality of first electrodes, a plurality of light-emitting functional layers, and a common second electrode are sequentially stacked corresponding to a plurality of subpixels constituting the display area, wherein the light-emitting element layer formation step involves moving a coating head having a plurality of nozzles and ejecting ink from the plurality of nozzles to form the plurality of light-emitting functional layers by an inkjet method, wherein the thin-film transistor layer formation step involves forming alignment marks on the outside of each of the plurality of display areas on the base substrate, and the light-emitting functional layer formation step involves using the alignment marks to form the base substrate The invention is characterized by comprising: a first step of aligning the alignment mark, dispensing and applying the ink so that it overlaps with the alignment mark, then dispensing and applying the ink while moving the application head, thereby forming the first layer of the plurality of light-emitting functional layers on the display area corresponding to the alignment mark with the applied coating film; a second step of firing the coating film applied in the first step; a third step of aligning the base substrate using the alignment mark, inspecting the fired coating film that overlaps with the alignment mark, then dispensing and applying the ink so that it overlaps with the alignment mark, dispensing and applying the ink while moving the application head, thereby forming the second layer of the plurality of light-emitting functional layers on the display area corresponding to the alignment mark with the applied coating film; and a fourth step of firing the coating film applied in the third step.

[0009] Furthermore, the present invention relates to a method for manufacturing a display device, comprising: a thin-film transistor layer formation step of forming thin-film transistor layers in each of the multiple display areas on a base substrate having a plurality of defined display areas; and a light-emitting element layer formation step of forming a light-emitting element layer on the thin-film transistor layer in which a plurality of first electrodes, a plurality of light-emitting functional layers, and a common second electrode are sequentially stacked corresponding to a plurality of subpixels constituting the display area, wherein in the light-emitting element layer formation step, ink is ejected from a plurality of nozzles while moving a coating head having a plurality of nozzles to form the plurality of light-emitting functional layers by an inkjet method, and in the thin-film transistor layer formation step The invention is characterized in that, in the process of forming the light-emitting functional layer, alignment marks are formed on the outside of each of the multiple display areas on the base substrate, and in the process of forming the multiple light-emitting functional layers, when forming the multiple first electrodes, the lower electrodes are formed using the same material as the multiple first electrodes so as to overlap with the alignment marks, when forming the multiple light-emitting functional layers, the light-emitting functional parts are formed using the same material as the multiple light-emitting functional layers so as to overlap with the alignment marks, and when forming the second electrodes, the upper electrodes are formed using the same material as the second electrodes so as to overlap with the alignment marks, and then the light-emitting functional parts are made to emit light via the lower electrodes and the upper electrodes for inspection.

[0010] According to the present invention, the quality of the light-emitting functional layer formed by the inkjet method can be confirmed at low cost.

[0011] Figure 1 is a plan view showing the schematic configuration of a QLED display device according to the first embodiment of the present invention. Figure 2 is a plan view of the display area of ​​a QLED display device according to the first embodiment of the present invention. Figure 3 is a cross-sectional view of the display area of ​​a QLED display device according to the first embodiment of the present invention. Figure 4 is an equivalent circuit diagram of the TFT layer constituting the QLED display device according to the first embodiment of the present invention. Figure 5 is a cross-sectional view of the QLED layer constituting the QLED display device according to the first embodiment of the present invention. Figure 6 is a plan view showing the QLED layer formation process in the manufacturing method of a QLED display device according to the first embodiment of the present invention. Figure 7 is a plan view of the coating head and alignment mark used in the QLED layer formation process in the manufacturing method of a QLED display device according to the first embodiment of the present invention. Figure 8 is a cross-sectional view showing the QLED layer formation process in the manufacturing method of a QLED display device according to the first embodiment of the present invention. Figure 9 is a cross-sectional view showing the inspection method of the QLED layer formation process in the manufacturing method of a QLED display device according to the first embodiment of the present invention. Figure 10 is a cross-sectional view showing the first half of the first step of the QLED layer formation process in the manufacturing method of a QLED display device according to the second embodiment of the present invention. Figure 11 is a cross-sectional view showing the second half of the first step of the QLED layer formation process in the manufacturing method of a QLED display device according to the second embodiment of the present invention. Figure 12 is a cross-sectional view showing the second step of the QLED layer formation process in the method for manufacturing a QLED display device according to the second embodiment of the present invention. Figure 13 is a cross-sectional view showing the first half of the third step of the QLED layer formation process in the method for manufacturing a QLED display device according to the second embodiment of the present invention. Figure 14 is a cross-sectional view showing the second half of the third step of the QLED layer formation process in the method for manufacturing a QLED display device according to the second embodiment of the present invention. Figure 15 is a cross-sectional view showing the fourth step of the QLED layer formation process in the method for manufacturing a QLED display device according to the second embodiment of the present invention. Figure 16 is a cross-sectional view showing the schematic configuration of the method for manufacturing a QLED display device according to the third embodiment of the present invention. Figure 17 is a photograph showing an evaluation element emitting light in the method for manufacturing a QLED display device according to the third embodiment of the present invention.

[0012] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments.

[0013] 《First Embodiment》 Figures 1 to 9 show a first embodiment of the method for manufacturing a display device according to the present invention. In the following embodiments, a QLED display device equipped with a QLED layer is exemplified as a display device equipped with a light-emitting layer. Here, Figure 1 is a plan view showing the schematic configuration of the QLED display device 50 of this embodiment. Figures 2 and 3 are a plan view and a cross-sectional view of the display area D of the QLED display device 50. Figure 4 is an equivalent circuit diagram of the TFT layer 30 constituting the QLED display device 50. Figure 5 is a cross-sectional view of the QLED layer 36 constituting the QLED display device 50.

[0014] As shown in Figure 1, the QLED display device 50 includes, for example, a display area D for displaying an image, which is provided in a rectangular shape, and a frame area F provided in a frame shape around the display area D. In this embodiment, a rectangular display area D is used as an example, but this rectangular shape also includes substantially rectangular shapes such as shapes with arc-shaped sides, shapes with arc-shaped corners, and shapes with notches in part of the sides.

[0015] In the display area D, as shown in Figure 2, multiple subpixels P are arranged in a matrix. Furthermore, in the display area D, as shown in Figure 2, for example, subpixels P having a red light-emitting region Lr for displaying red, subpixels P having a green light-emitting region Lg for displaying green, and subpixels P having a blue light-emitting region Lb for displaying blue are arranged adjacent to each other. Note that in the display area D, for example, one pixel is composed of three adjacent subpixels P having a red light-emitting region Lr, a green light-emitting region Lg, and a blue light-emitting region Lb.

[0016] As shown in Figure 1, the frame region F has a first peripheral circuit region Ra along the positive and negative sides in the X direction of the display region D. Also, as shown in Figure 1, the frame region F has a second peripheral circuit region Rb along the negative side in the Y direction of the display region D. Here, the first peripheral circuit region Ra is monolithically equipped with, for example, a gate drive circuit. The second peripheral circuit region Rb is equipped with, for example, an integrated circuit (IC) chip that constitutes a source drive circuit. Furthermore, as shown in Figure 1, the frame region F is provided with alignment marks M for aligning the resin base substrate 100, which will be described later. Here, as shown in Figure 7, the alignment marks M consist of an outer portion 14m provided in the shape of a square frame by a first metal film, which will be described later, and an inner portion 18m provided in the shape of a square by a third metal film, which will be described later, inside the outer portion 14m. In addition, the alignment mark M may have a notch formed in the outer portion 14m, or the outer portion 14m and the inner portion 18m may have overlapping portions.

[0017] As shown in Figure 3, the QLED display device 50 comprises a resin substrate 10 provided as a base substrate, a TFT layer 30 provided on the resin substrate 10, a QLED element layer 40 provided on the TFT layer 30 as a light-emitting element layer, and a sealing film 45 provided on the QLED element layer 40.

[0018] The resin substrate 10 is made of, for example, polyimide resin.

[0019] As shown in Figure 3, the TFT layer 30 comprises a base coat film 11 provided on a resin substrate 10, a plurality of first TFTs 9a, a plurality of second TFTs 9b, and a plurality of capacitors 9c provided on the base coat film 11, and a protective insulating film 19 and a planarization film 20 sequentially provided on each first TFT 9a, each second TFT 9b, and each capacitor 9c. Here, as shown in Figure 2, the TFT layer 30 is provided with a plurality of gate lines 14g extending parallel to each other in the X direction in the figure. Also, as shown in Figure 2, the TFT layer 30 is provided with a plurality of source lines 18f extending parallel to each other in a direction intersecting (orthogonal to) the plurality of gate lines 14g, i.e., in the Y direction in the figure. Also, as shown in Figure 2, the TFT layer 30 is provided with a plurality of power lines 18g extending parallel to each other in the Y direction in the figure. And, as shown in Figure 2, each power line 18g is provided adjacent to each source line 18f. Furthermore, in the TFT layer 30, as shown in Figure 4, a first TFT 9a, a second TFT 9b, and a capacitor 9c are provided in each subpixel P. In the TFT layer 30, as shown in Figure 3, a base coat film 11, a semiconductor film which will be a semiconductor layer 12a (described later), a first metal film which will be a gate insulating film 13, a gate line 14g, a first interlayer insulating film 15, a second metal film which will be an upper conductive layer 16c (described later), a second interlayer insulating film 17, a third metal film which will be a source line 18f or power line 18g, a protective insulating film 19, and a planarization film 20 are stacked in that order on the resin substrate 10.

[0020] The base coat film 11, gate insulating film 13, first interlayer insulating film 15, second interlayer insulating film 17, and protective insulating film 19 are composed of inorganic insulating films, such as single-layer or multilayer films, of silicon nitride, silicon oxide, or silicon oxynitride.

[0021] As shown in Figure 4, the first TFT 9a is electrically connected to the corresponding gate line 14g, source line 18f, and corresponding second TFT 9b at each subpixel P. Here, as shown in Figure 3, the first TFT 9a comprises a semiconductor layer 12a provided on a base coat film 11, a gate electrode 14a provided on the semiconductor layer 12a via a gate insulating film 13, and a source electrode 18a and a drain electrode 18b provided spaced apart from each other on the second interlayer insulating film 17.

[0022] The semiconductor layer 12a is formed from a semiconductor film made of polysilicon, such as LTPS (low temperature polysilicon), and comprises a source region and a drain region defined to be spaced apart from each other, and a channel region defined between the source region and the drain region.

[0023] The gate electrode 14a is provided so as to overlap the channel region of the semiconductor layer 12a and is configured to control conductivity between the source region and the drain region of the semiconductor layer 12a. Here, the gate electrode 14a is formed of a first metal film, similar to the gate wire 14g, etc.

[0024] As shown in Figure 3, the source electrode 18a and the drain electrode 18b are electrically connected to the source region and drain region of the semiconductor layer 12a, respectively, via contact holes formed in the gate insulating film 13, the first interlayer insulating film 15, and the second interlayer insulating film 17. Here, the source electrode 18a and the drain electrode 18b are formed from a third metal film, similar to the source wire 18f and the power supply wire 18g.

[0025] As shown in Figure 4, the second TFT 9b is electrically connected to the corresponding first TFT 9a, power line 18g, and QLED element 39 at each subpixel P. Here, as shown in Figure 3, the second TFT 9b comprises a semiconductor layer 12b provided on the base coat film 11, a gate electrode 14b provided on the semiconductor layer 12b via a gate insulating film 13, and a source electrode 18c and a drain electrode 18d provided spaced apart from each other on the second interlayer insulating film 17.

[0026] The semiconductor layer 12b, like the semiconductor layer 12a, is formed from a semiconductor film made of polysilicon such as LTPS, and comprises a source region and a drain region defined to be spaced apart from each other, and a channel region defined between the source region and the drain region.

[0027] The gate electrode 14b is provided so as to overlap the channel region of the semiconductor layer 12b and is configured to control conductivity between the source region and the drain region of the semiconductor layer 12b. Here, the gate electrode 14b is formed of a first metal film, similar to the gate wire 14g, etc.

[0028] As shown in Figure 3, the source electrode 18c and drain electrode 18d are electrically connected to the source region and drain region of the semiconductor layer 12b, respectively, through contact holes formed in the laminated film of the gate insulating film 13, the first interlayer insulating film 15, and the second interlayer insulating film 17. Here, the source electrode 18c and drain electrode 18d are formed from a third metal film, similar to the source wire 18f and power supply wire 18g.

[0029] In this embodiment, semiconductor layers 12a and 12b formed from a semiconductor film made of polysilicon are exemplified, but semiconductor layers 12a and 12b may be formed from a semiconductor film made of an oxide semiconductor such as In-Ga-Zn-O. Furthermore, the TFT layer 30 may have a hybrid structure in which a TFT having a semiconductor layer made of polysilicon and a TFT having a semiconductor layer made of an oxide semiconductor are provided.

[0030] As shown in Figure 4, the capacitor 9c is electrically connected to the corresponding first TFT 9a and power line 18g at each sub-pixel P. Here, as shown in Figure 3, the capacitor 9c comprises a lower conductive layer 14c formed of a first metal film, an upper conductive layer 16c formed of a second metal film, and a first interlayer insulating film 15 provided between the lower conductive layer 14c and the upper conductive layer 16c. The upper conductive layer 16c is electrically connected to the power line 18g via a contact hole formed in the second interlayer insulating film 17, as shown in Figure 3.

[0031] The planarized film 20 has a flat surface in the display area D and is made of an organic resin material such as polyimide resin.

[0032] As shown in Figure 3, the QLED element layer 40 comprises a plurality of third electrodes 31 stacked sequentially corresponding to a plurality of subpixels P, a common first edge cover 33, a plurality of first electrodes 34, a common second edge cover 35, a plurality of QLED layers 36, and a common second electrode 37. Here, in each subpixel P, the third electrode 31, the first electrode 34, the QLED layer 36, and the second electrode 37 constitute a QLED element 39, as shown in Figure 3, and in the QLED element layer 40, a plurality of QLED elements 39 are arranged in a matrix corresponding to a plurality of subpixels P.

[0033] As shown in Figure 3, the third electrode 31 is electrically connected to the drain electrode 18d of the second TFT 9b of each subpixel P via contact holes formed in the protective insulating film 19 and the planarization film 20. Here, the third electrode 31 is formed of a transparent conductive film such as indium tin oxide (hereinafter also referred to as "ITO") and has light transmittance.

[0034] The first edge cover 33 is provided in a grid pattern across the entire display area D, and as shown in Figures 3 and 4, it is provided to cover the peripheral end of the third electrode 31. The first edge cover 33 is made of, for example, an organic resin material such as polyimide resin or acrylic resin, or a polysiloxane-based SOG (spin on glass) material.

[0035] The first electrode 34 has the function of injecting holes into the QLED layer 36, and as shown in Figure 3, it is provided so as to cover the third electrode 31 that is exposed from the first edge cover 33. Furthermore, in order to improve the hole injection efficiency into the QLED layer 36, it is more preferable to form the first electrode 34 from a material with a large work function. Here, the first electrode 34 is formed from a laminated film in which a transparent conductive film such as ITO, a metal film such as silver (Ag), and a transparent conductive film such as ITO are sequentially laminated, and has light reflectivity.

[0036] The second edge cover 35 is provided in a grid pattern across the entire display area D, and as shown in Figure 3, it is provided to cover the peripheral end of the first electrode 34. Here, the second edge cover 35 is made of an inorganic insulating film, such as a single layer or multilayer film of silicon nitride, silicon oxide, or silicon oxynitride.

[0037] The QLED layer 36 is provided as a light-emitting functional layer and, as shown in Figure 6, comprises a hole injection layer 1, a hole transport layer 2, a light-emitting layer 3, and an electron transport layer 4 stacked sequentially on the first electrode 34. In this embodiment, a configuration in which each of the multiple light-emitting functional layers is a QLED layer 36 is illustrated, but at least one of the multiple light-emitting functional layers may be a QLED layer 36.

[0038] The hole injection layer 1, also called the anode buffer layer, has the function of bringing the energy levels of the first electrode 34 and the QLED layer 36 closer together, thereby improving the hole injection efficiency from the first electrode 34 to the QLED layer 36. Examples of materials constituting the hole injection layer 1 include, as organic materials, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, phenylenediamine derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, etc., and as inorganic materials, it contains at least one nanoparticle. The nanoparticle may, for example, contain nickel oxide (NiO) and further contain nitrate ions (NO₂). ３ － It includes ).

[0039] The hole transport layer 2 has the function of improving the efficiency of hole transport from the first electrode 34 to the QLED layer 36. Here, examples of materials that constitute the hole transport layer 2 include conventionally used materials such as porphyrin derivatives, aromatic tertiary amine compounds, styrylamine derivatives, polyvinylcarbazole, poly-p-phenylenevinylene, polysilane, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amine-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, hydrogenated amorphous silicon, hydrogenated amorphous silicon carbide, zinc sulfide, and zinc selenide. Furthermore, examples of materials that constitute the hole transport layer 2 include functional polymer materials such as poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)] (abbreviated as "TFB"), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (abbreviated as "poly-TPD"), and polyvinylcarbazole (abbreviated as "PVK"). The material that constitutes the hole transport layer 2 may consist of only one of the above-mentioned materials, or may consist of two or more as appropriate.

[0040] The light-emitting layer 3 is a region in which holes and electrons are injected from the first electrode 34 and the second electrode 37, respectively, when a voltage is applied by the first electrode 34 and the second electrode 37, and where the holes and electrons recombine. Here, the light-emitting layer 3 is formed of a material with high luminescence efficiency. The light-emitting layer 3 includes, for example, a plurality of quantum dots as the light-emitting material. Furthermore, each quantum dot constituting the light-emitting layer 3 may have a core / shell structure including a core that emits light when excitons are used and a shell formed around the core to protect it. In this embodiment, the light-emitting layer 3 may also include an organic or inorganic ligand that coordinates to each quantum dot by forming a coordination bond with the outermost surface of each quantum dot.

[0041] Note that in this embodiment, the "quantum dot" means a dot with a maximum width of 100 nm or less. Further, the shape of the quantum dot only needs to satisfy the above maximum width, and is not particularly limited, and is not limited to a spherical three-dimensional shape (circular cross-sectional shape). Furthermore, the shape of the quantum dot may be, for example, a polygonal cross-sectional shape, a rod-shaped three-dimensional shape, a dendritic three-dimensional shape, a three-dimensional shape having irregularities on the surface, or a combination thereof.

[0042] The quantum dot is typically preferably made of a semiconductor. Here, the semiconductor preferably has a certain bandgap. Further, the semiconductor may be any material that can emit light, and preferably contains at least the materials described below. Further, the semiconductor preferably can emit blue, green, and red light, respectively. Further, the semiconductor contains, for example, at least one selected from the group consisting of II-VI group compounds, III-V group compounds, chalcogenides, and perovskite compounds. Note that the II-VI group compound means a compound containing a group II element and a group VI element, and the III-V group compound means a compound containing a group III element and a group V element. Further, the group II element includes a group 2 element and a group 12 element, the group III element includes a group 3 element and a group 13 element, the group V element includes a group 5 element and a group 15 element, and the group VI element may include a group 6 element and a group 16 element.

[0043] The II-VI group compound contains, for example, at least one selected from the group consisting of MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe.

[0044] The III-V group compound contains, for example, at least one selected from the group consisting of GaAs, GaP, InN, InAs, InP, and InSb.

[0045] The chalcogenide is a compound containing a group VIA (16) element, and for example, contains CdS or CdSe. Further, the chalcogenide may also contain a mixed crystal thereof.

[0046] The perovskite compound has, for example, a composition represented by the general formula CsPbX ３ and contains at least one selected from the group consisting of, for example, Cl, Br, and I as a constituent element X.

[0047] Note that the notation of the group number of an element using Roman numerals is based on the old IUPAC (International Union of Pure and Applied Chemistry) system or the old CAS (Chemical Abstracts Service) system, and the notation of the group number of an element using Arabic numerals is based on the current IUPAC system.

[0048] The electron transport layer 4 has a function of efficiently moving electrons to the light-emitting layer 3. Here, examples of the material constituting the electron transport layer 4 include, as organic compounds, oxadiazole derivatives, triazole derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, tetracyanoanthraquinodimethane derivatives, diphenoquinone derivatives, fluorenone derivatives, silole derivatives, metal oxynoid compounds, etc., and inorganic materials can be used. Further, the material constituting the electron transport layer 4 may contain zinc oxide (ZnO), magnesium zinc oxide (MgZnO), etc. Furthermore, the material constituting the electron transport layer 4 may contain only one kind of the above-described materials, or may contain two or more kinds as appropriate.

[0049] As shown in FIG. 3, the second electrode 37 is provided so as to cover each QLED layer 36 and the second edge cover 35. Further, the second electrode 37 has a function of injecting electrons into the QLED layer 36. Also, the second electrode 37 is more preferably composed of a material having a small work function in order to improve the electron injection efficiency into the QLED layer 36. Here, the second electrode 37 is formed of, for example, a transparent conductive film such as ITO and has light transmissivity.

[0050] As shown in Figure 3, the sealing film 45 is provided so as to cover the second electrode 37 and comprises a first inorganic sealing film 41, an organic sealing film 42, and a second inorganic sealing film 43 that are sequentially laminated on the second electrode 37, and has the function of protecting the QLED layer 36 of the QLED element 39 from moisture, oxygen, etc. Here, the first inorganic sealing film 41 and the second inorganic sealing film 43 are made of inorganic insulating films such as silicon nitride film, silicon oxide film, or silicon oxynitride film. The organic sealing film 42 is made of an organic resin material such as acrylic resin, epoxy resin, silicone resin, polyurea resin, parylene resin, polyimide resin, or polyamide resin.

[0051] The QLED display device 50 described above is configured such that, at each subpixel P, a gate signal is input to the first TFT 9a via the gate line 14g, turning the first TFT 9a into an ON state. A data signal is then written to the gate electrode 14b and capacitor 9c of the second TFT 9b via the source line 18f. A current from the power line 18g corresponding to the gate voltage of the second TFT 9b is supplied to the QLED layer 36 of the QLED element 39, causing the light-emitting layer 3 of the QLED layer 36 to emit light and display an image. In the QLED display device 50, even if the first TFT 9a is turned OFF, the gate voltage of the second TFT 9b is maintained by the capacitor 9c, so the light emission from the light-emitting layer 3 is maintained until the gate signal for the next frame is input.

[0052] In this embodiment, a QLED display device 50 equipped with a third electrode 31 and a first edge cover 33 is provided as an example, but the third electrode 31 and the first edge cover 33 may be omitted.

[0053] Furthermore, in this embodiment, a top-emission type QLED display device 50 is exemplified in which the third electrode 31 and the second electrode 37 are light-transmitting and the first electrode 34 is light-reflective. However, a bottom-emission type may also be used in which the third electrode 31 and the first electrode 34 are light-transmitting and the second electrode 37 is light-reflective.

[0054] Next, an example of a method for manufacturing the QLED display device 50 of this embodiment will be described. Here, Figure 6 is a plan view showing the QLED layer formation process in the method for manufacturing the QLED display device 50. Figure 7 is a plan view of the coating head 110 and alignment mark M used in the QLED layer formation process in the method for manufacturing the QLED display device 50. Figure 8 is a cross-sectional view showing the QLED layer formation process in the method for manufacturing the QLED display device 50. It is also a cross-sectional view showing the inspection method for the QLED layer formation process in the method for manufacturing the QLED display device 50. The method for manufacturing the QLED display device 50 of this embodiment comprises a TFT layer formation process, a QLED element layer formation process including a QLED layer formation process, a sealing film formation process, and a piece formation process.

[0055] <TFT Layer Formation Process> First, a base coat film 11 is formed on a resin substrate 100, which is formed on a glass substrate as a base substrate (with multiple display areas D defined), by sequentially depositing a silicon nitride film (approximately 50 nm thick) and a silicon oxide film (approximately 250 nm thick) using, for example, a plasma CVD (Chemical Vapor Deposition) method.

[0056] Next, an amorphous silicon film (approximately 50 nm thick) is deposited on the substrate surface on which the base coat film 11 is formed, for example by plasma CVD. The amorphous silicon film is then crystallized by laser annealing or the like to form a semiconductor film made of polysilicon. After that, the semiconductor film is patterned to form semiconductor layers 12a and 12b, etc., in each display area D.

[0057] Subsequently, a gate insulating film 13 is formed on the substrate surface on which the semiconductor layer 12a etc. is formed by depositing a silicon oxide film (approximately 100 nm thick) using, for example, a plasma CVD method.

[0058] Furthermore, a first metal film, such as a molybdenum film (approximately 200 nm thick), is formed on the substrate surface on which the gate insulating film 13 is formed, for example, by sputtering. Then, the first metal film is patterned to form gate lines 14g, gate electrodes 14a and 14b, etc., in each display area D, and the outer portion 14m of the alignment mark M is formed in each frame area F.

[0059] Next, using the gate electrodes 14a and 14b as masks, impurity ions are doped into the semiconductor layers 12a and 12b to make a portion of the semiconductor layers 12a and 12b conductive, thereby forming a source region, a drain region, and a channel region in the semiconductor layers 12a and 12b, respectively.

[0060] Subsequently, a first interlayer insulating film 15 is formed on the substrate surface, where a portion of the semiconductor layers 12a and 12b have been made conductive, by sequentially depositing a silicon nitride film (approximately 150 nm thick) and a silicon oxide film (approximately 100 nm thick) using, for example, a plasma CVD method.

[0061] Furthermore, a second metal film, such as a molybdenum film (approximately 200 nm thick), is formed on the substrate surface on which the first interlayer insulating film 15 is formed, for example, by sputtering. After that, the second metal film is patterned to form an upper conductive layer 16c, etc., in each display area D.

[0062] Subsequently, a second interlayer insulating film 17 is formed on the substrate surface on which the upper conductive layer 16c etc. is formed, by sequentially depositing a silicon oxide film (approximately 300 nm thick) and a silicon nitride film (approximately 150 nm thick) using, for example, a plasma CVD method.

[0063] Next, on the substrate surface on which the second interlayer insulating film 17 is formed, contact holes are formed in each display area D by appropriately patterning the first gate insulating film 13, the first interlayer insulating film 15, and the second interlayer insulating film 17.

[0064] Subsequently, a third metal film is formed on the substrate surface where the contact holes are formed by sequentially depositing, for example, a titanium film (approximately 50 nm thick), an aluminum film (approximately 400 nm thick), and a titanium film (approximately 100 nm thick) by sputtering. Then, the third metal film is patterned to form source lines 18f, power lines 18g, source electrodes 18a and 18c, and drain electrodes 18b and 18d in each display area D, and the inner portion 18m of the alignment mark M is formed in each frame area F.

[0065] Furthermore, a protective insulating film 19 is formed on the substrate surface on which the source lines 18f, etc., are formed, by depositing a silicon oxide film (approximately 250 nm thick) using, for example, a plasma CVD method.

[0066] Next, an acrylic photosensitive resin film (approximately 2 μm thick) is applied to the substrate surface on which the protective insulating film 19 is formed, for example, by a spin coating method or a slit coating method. Then, a planarization film 20 having contact holes is formed by pre-baking, exposure, development, and post-baking of the coated film.

[0067] Finally, the protective insulating film 19 exposed through the contact holes of the planarization film 20 is removed, allowing the contact holes to reach the drain electrode 18d of the second TFT 9b.

[0068] As described above, a TFT layer 30 can be formed in each display area D on the resin substrate 100.

[0069] <QLED element layer formation process> First, on the substrate surface on which the TFT layer 30 was formed in the TFT layer formation process described above, a transparent conductive film such as an ITO film (approximately 100 nm thick) is formed by, for example, sputtering, and then the transparent conductive film is patterned to form the third electrode 31 in each display area D.

[0070] Next, an acrylic-based negative-type photosensitive resin film (approximately 2 μm thick) is applied to the substrate surface on which the third electrode 31 is formed, for example, by a spin coating method or a slit coating method. Then, the coated film is subjected to pre-baking, exposure, development, and post-baking to form the first edge cover 33 in each display area D.

[0071] Subsequently, on the substrate surface on which the first edge cover 33 is formed, a transparent conductive film such as an ITO film (approximately 40 nm thick), a metal film such as an Ag film (approximately 20 nm thick), and another transparent conductive film such as an ITO film (approximately 40 nm thick) are sequentially deposited by, for example, a sputtering method. After these laminated films are patterned, the first electrode 34 is formed in each display area D.

[0072] Furthermore, an inorganic insulating film, such as a silicon nitride film (approximately 250 nm thick), is deposited on the substrate surface on which the first electrode 34, etc., is formed, for example, by plasma CVD. The inorganic insulating film is then patterned to form the second edge cover 35 in each display area D.

[0073] Next, as shown in Figures 6 and 8, a coating head 110, which has a plurality of nozzles N (see Figure 7) on its lower surface, is moved, and ink containing nanoparticles of the above-mentioned constituent materials dissolved in it is ejected from the nozzles N, thereby forming a hole injection layer 1 in each display area D by inkjet method. Here, the gap G (distance between centers, see Figure 7) of the plurality of nozzles N provided on the coating head 110 is, for example, about 35 μm. Also, the height H (see Figure 7) of the alignment mark M along the Y direction in Figure 6 is, for example, about 200 μm. In the resin base substrate 100, the plurality of display areas D are each provided in a rectangular shape in a plan view, as shown in Figure 6, and are arranged in a line along their shorter side. Also, in Figure 8, the third electrode 31, the first edge cover 33, and the second edge cover 35 are omitted from the illustration. The dashed arrow in Figure 6 indicates the direction of movement of the coating head 110.

[0074] Specifically, when forming hole injection layers 1 in multiple display areas D, as shown in Figures 6 and 8, (a) first, the resin base substrate 100 is aligned using the alignment mark M and CCD camera C corresponding to the first display area D. (b) Next, ink is dispensed and applied so as to overlap with the (input side) alignment mark M, and the applied coating film J is inspected. Here, in the inspection of the coating film J, as shown in Figure 9, the coating film J is imaged by the CCD camera C, and the quality of the coating film J is confirmed by performing image analysis using, for example, reflected light. (c) After that, as shown in Figure 8, ink is dispensed and applied while moving the coating head 110 to the positive side in the X direction in Figure 6, and multiple hole injection layers 1 (before firing) are formed with the applied coating film. (d) Furthermore, ink is dispensed and applied so as to overlap with the (exit side) alignment mark M of the first display area D, and the applied coating film J is inspected as described above. If an abnormality is found in the inspection nozzle N of the coated film J, the coating head 110 will be stopped, and the clogged nozzle N will be cleaned or the coating head 110 will be replaced.

[0075] Subsequently, without ejecting ink, the coating head 110 is moved to the positive side in the Y direction in Figure 6, and before coating the second display area D, as in (b) above, ink is ejected and applied so as to overlap with the input alignment mark M corresponding to the second display area D, and the applied coating film J is inspected. Then, as in (c) above, ink is ejected from the nozzle N while moving the coating head 110 to the negative side in the X direction in Figure 6 to form multiple hole-injected layers 1 (before firing) over the entire second display area D, and then, as in (d) above, ink is ejected and applied so as to overlap with the output alignment mark M corresponding to the second display area D, and the applied coating film J is inspected.

[0076] Subsequently, multiple hole-injected layers 1 (before firing) are formed on the third to fifth display areas D (and their alignment marks M) by ejecting and applying ink as described in (b) to (d) above. After firing the multiple hole-injected layers 1 (before firing), multiple hole-injected layers 1 (before firing) are formed on each display area D. For the formation of the hole-injected layers 1, an organic solvent such as ethylene glycol is used as the solvent for the ink, and firing is performed at approximately 200°C.

[0077] Furthermore, on the substrate surface on which multiple hole injection layers 1 are formed, multiple hole transport layers 2 are formed in each display area D by inkjet, similar to the method for forming the hole injection layers 1 described above. For the formation of the hole transport layers 2, an organic solvent such as butyl carbitol acetate is used as the solvent for the ink, and the layers are fired at approximately 200°C.

[0078] Subsequently, after forming a resist pattern on the substrate surface on which multiple hole transport layers 2 are formed, for example, a solution (dispersion) containing nanoparticles in which the above-mentioned constituent materials are dissolved (dispersed) is applied, and a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer are sequentially formed by the lift-off method, thereby forming multiple light-emitting layers 3 in each display area D.

[0079] Furthermore, on the substrate surface on which multiple light-emitting layers 3 are formed, multiple electron transport layers 4 are formed in each display area D by an inkjet method, similar to the method for forming the hole injection layer 1 described above, to form multiple QLED layers 36 (QLED layer formation step). For the formation of the electron transport layers 4, an organic solvent such as an alcohol-based solvent is used as the solvent for the ink, and it is fired at about 80°C.

[0080] Finally, a transparent conductive film, such as an ITO film (approximately 100 nm thick), is deposited on the substrate surface on which multiple QLED layers 36 are formed using a mask by sputtering to form a second electrode 37 in each display area D.

[0081] As described above, a QLED element layer 40 can be formed on each TFT layer 30.

[0082] <Encapsulation Film Formation Process> First, an inorganic insulating film, such as a silicon nitride film, a silicon oxide film, or a silicon oxynitride film, is deposited on the substrate surface on which the QLED element layer 40 was formed in the above QLED element layer formation process using a mask by plasma CVD to form a first inorganic encapsulation film 41 in each display area D.

[0083] Next, an organic resin material such as acrylic resin is deposited on the substrate surface on which the first inorganic encapsulation film 41 is formed, for example by an inkjet method, to form an organic encapsulation film 42 in each display area D.

[0084] Furthermore, an inorganic insulating film, such as a silicon nitride film, a silicon oxide film, or a silicon oxynitride film, is deposited on the substrate on which the organic encapsulation film 42 is formed, using a mask and a plasma CVD method to form a second inorganic encapsulation film 43 in each display area D, thereby forming the encapsulation film 45.

[0085] As described above, a sealing film 45 can be formed on each QLED element layer 40.

[0086] <Separation Process> First, a protective sheet (not shown) is attached to the substrate surface on which the sealing film 45 has been formed in the sealing film formation process described above. Then, by irradiating the resin substrate 100 with laser light from the glass substrate side, the glass substrate is peeled off from the bottom surface of the resin substrate 100. Furthermore, a protective sheet (not shown) is attached to the bottom surface of the resin substrate 100 from which the glass substrate has been peeled off.

[0087] Furthermore, a base substrate (a resin base substrate 100 and layers formed on the resin base substrate 100 (for example, a base coat film 11, a gate insulating film 13, a first interlayer insulating film 15, a second interlayer insulating film 17, a protective insulating film 19, a planarization film 20, etc.)) on which multiple QLED display devices 50 with protective sheets attached are arranged in a matrix is ​​divided into display areas D by, for example, irradiation with laser light, to cut out each QLED display device 50 individually and make them into individual pieces.

[0088] As described above, the QLED display device 50 of this embodiment can be manufactured.

[0089] As described above, according to the manufacturing method of the QLED display device 50 of this embodiment, in the TFT layer formation step, alignment marks M are formed on the outside of each of the multiple display areas D on the resin substrate 100. Then, in the QLED layer formation step, the resin substrate 100 is aligned using the alignment marks M and the CCD camera C, ink is ejected and applied so as to overlap with the alignment marks M, and after inspecting the applied coating film J, ink is ejected and applied while moving the coating head 110, and multiple hole injection layers 1, multiple hole transport layers 2, and multiple electron transport layers 4 are formed on the display areas D corresponding to the alignment marks M using the applied coating film, thereby forming multiple QLED layers 36. Here, for inspection of the coating film J, the coating film J is imaged using the CCD camera C used for alignment, and the quality of the coating film J can be confirmed by performing image analysis, so the quality of the QLED layers 36 (hole injection layer 1, hole transport layer 2, and electron transport layer 4) formed by the inkjet method can be confirmed at low cost.

[0090] 《Second Embodiment》 Figures 10 to 15 show a second embodiment of the method for manufacturing a display device according to the present invention. Here, Figures 10 and 11 are cross-sectional views showing the first half and second half of the first step of the QLED layer formation process in the method for manufacturing the QLED display device 50 of this embodiment. Figure 12 is a cross-sectional view showing the second step of the QLED layer formation process in the method for manufacturing the QLED display device 50 of this embodiment. Figures 13 and 14 are cross-sectional views showing the first half and second half of the third step of the QLED layer formation process in the method for manufacturing the QLED display device 50 of this embodiment. Figure 15 is a cross-sectional view showing the fourth step of the QLED layer formation process in the method for manufacturing the QLED display device 50 of this embodiment. In the following embodiments, the same reference numerals are used for parts that are the same as those in Figures 1 to 9, and their detailed descriptions are omitted.

[0091] In the first embodiment described above, a method for manufacturing a QLED display device 50 was illustrated in which ink is applied to alignment marks M and the applied coating film is inspected before firing. In this embodiment, however, a method for manufacturing a QLED display device 50 is illustrated in which ink is applied to alignment marks M and the applied coating film is inspected after firing. Here, the QLED display device 50 in this embodiment is the same as the QLED display device 50 in the first embodiment described above, so its manufacturing method will be explained. Note that the manufacturing method of the QLED display device 50 in this embodiment includes a TFT layer formation step, a QLED element layer formation step including a QLED layer formation step, a sealing film formation step, and a piece formation step, similar to the first embodiment. Therefore, in this embodiment, the QLED layer formation step, which differs from the manufacturing method in the first embodiment, will be explained in detail.

[0092] First, in the QLED element layer formation process of the first embodiment described above, the resin base substrate 100 on which the second edge cover 35 is formed is aligned using alignment marks M and a CCD camera C, as shown in Figure 10. Note that the third electrode 31, the first edge cover 33, and the second edge cover 35 are not shown in Figures 10 to 15.

[0093] Next, ink is dispensed and applied so as to overlap with the (input side) alignment mark M corresponding to the first display area D, forming a coated film Jaw. Then, as shown in Figure 11, ink is dispensed and applied while moving the coating head 110, forming multiple hole injection layers 1 (before firing) with the applied coated film 1w, and ink is dispensed and applied so as to overlap with the (exit side) alignment mark M, forming a coated film Jaw. Furthermore, similar to the first embodiment described above, multiple hole injection layers 1 (before firing) and coated film Jaws are formed for each of the second to fifth display areas D (first step).

[0094] Subsequently, the resin substrate 100 coated with the coating film 1w and Jaw in the first step is placed, for example, on a hot plate, and the coating film 1w and Jaw are baked at about 200°C to form the hole injection layer 1 and the coating film Jad, as shown in Figure 12 (second step).

[0095] Furthermore, as shown in Figure 13, the resin base substrate 100 is aligned using the alignment mark M and the CCD camera C, and the fired coated film Jad that overlaps with the alignment mark M is inspected. In this inspection of the coated film Jad, the coated film Jad is imaged by the CCD camera C, and the quality of the coated film Jad is confirmed by image analysis.

[0096] Next, ink is dispensed and applied so as to overlap with the (input side) alignment mark M corresponding to the first display area D, forming the coated film Jbw. Then, as shown in Figure 14, ink is dispensed and applied while moving the coating head 110, forming multiple hole transport layers 2 (before firing) with the applied coated film 2w, and ink is dispensed and applied so as to overlap with the (exit side) alignment mark M, forming the coated film Jbw. Furthermore, in the same manner as the method for forming the hole injection layer 1 and coated film Jad described above, multiple hole transport layers 2 (before firing) and coated films Jbw are formed for each of the second to fifth display areas D (third step).

[0097] Subsequently, the resin substrate 100 coated with the coating films 2w and Jbw in the third step is placed, for example, on a hot plate, and the coating films 2w and Jbw are baked at approximately 200°C to form the hole transport layer 2 and coating film Jbd, as shown in Figure 15 (fourth step).

[0098] Next, after forming a resist pattern on the substrate surface on which multiple hole transport layers 2 are formed, for example, a solution (dispersion) containing nanoparticles in which the above-mentioned constituent materials are dissolved (dispersed) is applied, and a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer are sequentially formed by the lift-off method, thereby forming multiple light-emitting layers 3 in each display area D. The hole transport layers 2 are inspected when aligning the resin base substrate 100 on which the multiple hole transport layers 2 are formed in order to form the light-emitting layers 3.

[0099] Subsequently, on the substrate surface on which multiple light-emitting layers 3 are formed, multiple electron transport layers 4 are formed in each display area D by inkjet, similar to the method for forming the hole injection layer 1 described above, to form multiple QLED layers 36 (QLED layer formation step).

[0100] Subsequently, similar to the first embodiment described above, the QLED display device 50 of this embodiment can be manufactured by forming a second electrode 37 in each display area D, thereby forming a QLED element layer 40 on each TFT layer 30, followed by a sealing film formation process and a framing process. The electron transport layer 4 is inspected when aligning the resin base substrate 100 on which multiple electron transport layers 4 are formed in order to form the second electrode 37.

[0101] As described above, according to the manufacturing method of the QLED display device 50 of this embodiment, in the TFT layer formation step, alignment marks M are formed on the outside of each of the multiple display areas D on the resin substrate 100. Then, in the QLED layer formation step, in the third step of forming multiple hole transport layers 2 (before firing), when aligning the resin substrate 100 using the alignment marks M and the CCD camera C, the coated film Jad, which was ejected and applied in the first step so as to overlap with the alignment marks M and fired in the second step, is inspected. Here, in inspecting the coated film Jad, the coated film Jad is imaged using the CCD camera C used for alignment, and the quality of the coated film Jad can be confirmed by performing image analysis, so that the quality of the QLED layer 36 (hole injection layer 1, hole transport layer 2, and electron transport layer 4) formed by the inkjet method can be confirmed at low cost.

[0102] <Third Embodiment> Figures 16 and 17 show a third embodiment of the method for manufacturing a display device according to the present invention. Here, Figure 16 is a cross-sectional view showing the rigidity of the method for manufacturing the QLED display device 50 of this embodiment. Figure 17 is a photograph showing the evaluation element T emitting light, illustrating the method for manufacturing the QLED display device 50 of this embodiment.

[0103] In the first and second embodiments described above, a method for manufacturing a QLED display device 50 was illustrated in which ink is applied to alignment marks M and the applied coating film is inspected before and after firing. In this embodiment, however, an example of a method for manufacturing a QLED display device 50 is illustrated in which an evaluation element T is formed on the alignment marks M and the evaluation element T is made to emit light for inspection. Here, the QLED display device 50 in this embodiment is the same as the QLED display device 50 in the first embodiment described above, so its manufacturing method will be explained. Note that the manufacturing method of the QLED display device 50 in this embodiment includes a TFT layer formation step, a QLED element layer formation step including a QLED layer formation step, a sealing film formation step, and a piece formation step, similar to the first embodiment. Therefore, in this embodiment, the QLED layer formation step, which differs from the manufacturing method in the first embodiment, will be explained in detail.

[0104] First, in the QLED element layer formation process of the first embodiment described above, when forming the first electrode 34, the lower electrode 34m (see Figure 16) is formed on the inner portion 18m of the alignment mark M.

[0105] Next, an inorganic insulating film, such as a silicon nitride film (approximately 250 nm thick), is deposited on the substrate surface on which the first electrode 34 and the like are formed, for example by plasma CVD. The inorganic insulating film is then patterned to form the second edge cover 35 in each display area D.

[0106] Subsequently, similar to the second embodiment described above, the resin base substrate 100 on which the second edge cover 35 is formed is aligned using the alignment mark M and the CCD camera C.

[0107] Subsequently, similar to the second embodiment described above, ink is dispensed and applied so as to overlap with the (input side) alignment marks M corresponding to the first to fifth display areas D, forming a coated film Jaw (see Figure 11). Then, ink is dispensed and applied while moving the coating head 110, forming multiple hole injection layers 1 (before firing) with the applied coated film 1w (see Figure 11), and ink is dispensed and applied so as to overlap with the (exit side) alignment marks M, forming a coated film Jaw.

[0108] Furthermore, similar to the second embodiment described above, the coated film 1w and Ja are fired to form the hole injection layer 1 and the first light-emitting functional part Ja (see Figure 16).

[0109] Next, similar to the second embodiment described above, multiple hole transport layers 2, multiple light-emitting layers 3, and multiple electron transport layers 4 are sequentially formed in each display area D to form multiple QLED layers 36. When forming the hole transport layers 2, light-emitting layers 3, and electron transport layers 4 in the display area D, the second light-emitting function section Jb, the third light-emitting function section Jc, and the fourth light-emitting function section Jd (see Figure 16) are formed so as to overlap with the alignment mark M.

[0110] Subsequently, similar to the first embodiment described above, the QLED display device 50 of this embodiment can be manufactured by forming a second electrode 37 in each display area D, thereby forming a QLED element layer 40 on each TFT layer 30, followed by a sealing film formation process and a piecemaking process. Here, when forming the second electrode 37, an upper electrode 37m (see Figure 16) is formed so as to overlap with the alignment mark M. This makes it possible to form an evaluation element T on the inner portion 18m of the alignment mark M, in which a lower electrode 34m made of the same material as the first electrode 34, a first light-emitting function part Ja made of the same material as the hole injection layer 1, a second light-emitting function part Jb made of the same material as the hole transport layer 2, a third light-emitting function part Jc made of the same material as the light-emitting layer 3, a fourth light-emitting function part Jd made of the same material as the electron transport layer 4, and an upper electrode 37m made of the same material as the second electrode 37 are sequentially stacked. Then, by inputting inspection signals to the lower electrode 34m and the upper electrode 37m and causing the evaluation element T to emit light as shown in Figure 17, it is possible to detect nozzle clogging of the nozzle N of the coating head 110 by the streaky unevenness extending in the X direction in Figure 17, and to check the quality of the hole injection layer 1, the hole transport layer 2, and the electron transport layer 4. Note that the X and Y directions in Figure 17 coincide with the X and Y directions in Figure 7, and the X direction in those figures is the direction of movement of the coating head 110 when ejecting ink.

[0111] As described above, according to the manufacturing method of the QLED display device 50 of this embodiment, in the TFT layer formation step, alignment marks M are formed on the outside of each of the multiple display areas D on the resin substrate 100. Then, in the QLED layer formation step, when forming the first electrode 34 and the second electrode 37, the lower electrode 34m and the upper electrode 37m are formed so as to overlap with the alignment marks M, and when forming the multiple QLED layers 36 (hole injection layer 1, hole transport layer 2, and electron transport layer 4) by inkjet, the first light-emitting function part Ja, the second light-emitting function part Jb, and the fourth light-emitting function part Jd are formed so as to overlap with the alignment marks M, thereby enabling the formation of evaluation elements T on the alignment marks M. Furthermore, by inputting inspection signals to the lower electrode 34m and the upper electrode 37m and causing the evaluation elements T to emit light, the quality of the hole injection layer 1, hole transport layer 2, and electron transport layer 4 can be confirmed. Here, the quality of the hole injection layer 1, hole transport layer 2, and electron transport layer 4 can be confirmed by imaging the illuminated evaluation element T using a CCD camera C, which is used for alignment. Thus, the quality of the QLED layer 36 (hole injection layer 1, hole transport layer 2, and electron transport layer 4) formed by the inkjet method can be confirmed at low cost.

[0112] <Other Embodiments> In the first embodiment described above, a method for manufacturing a display device was shown in which the coated film is inspected before firing, in the second embodiment in which the coated film is inspected after firing, and in the third embodiment in which an evaluation element T is made to emit light for inspection. However, the present invention can also be applied to methods for manufacturing a display device by appropriately combining the methods for manufacturing a display device of the first to third embodiments described above.

[0113] Furthermore, while the above embodiments illustrate methods for manufacturing a display device in which coating is performed on both the forward and return paths of the coating head, the present invention can also be applied to methods for manufacturing a display device in which coating is performed on only one of the forward or return paths of the coating head.

[0114] Furthermore, while the above embodiments illustrate a method for manufacturing a display device in which an entire display area is coated with a single coating pass during the forward or return journey of the coating head, the present invention can also be applied to a method for manufacturing a display device in which an entire display area is coated with multiple coating passes during the forward and return journeys of the coating head.

[0115] Furthermore, while the above embodiments illustrate QLED display devices in which the first electrode is the anode and the second electrode is the cathode, the present invention can also be applied to QLED display devices in which the stacked structure of the QLED layer is reversed, with the first electrode being the cathode and the second electrode being the anode.

[0116] Furthermore, while the above embodiments illustrate a display device in which the electrode of a TFT electrically connected to the first electrode is used as the drain electrode, the present invention can also be applied to a display device in which the electrode of the TFT electrically connected to the first electrode is called the source electrode.

[0117] Furthermore, although the above embodiments described an example of a QLED display device, the present invention can be applied to a display device equipped with a plurality of light-emitting elements driven by electric current, for example, an organic electroluminescent display device equipped with OLEDs.

[0118] As described above, the present invention is useful for self-illuminating display devices.

[0119] D Display area J Coating film Ja First light-emitting function part Jad, Jaw Coating film Jb Second light-emitting function part Jbd, Jbw Coating film Jd Fourth light-emitting function part M Alignment mark N Nozzle P Subpixel 1 Hole injection layer (first layer of light-emitting function layer) 2 Hole transport layer (second layer of light-emitting function layer) 30 TFT layer (thin film transistor layer) 34 First electrode 34m Lower electrode 36 QLED layer (quantum dot light-emitting diode layer, light-emitting function layer) 37 Second electrode 37m Upper electrode 40 QLED element layer (light-emitting element layer) 45 Encapsulation film 50 QLED display device 100 Resin substrate (base substrate) 110 Coating head

Claims

1. A method for manufacturing a display device comprising: a thin-film transistor layer formation step of forming thin-film transistor layers in each of the multiple display areas defined on a base substrate; and a light-emitting element layer formation step of forming a light-emitting element layer on the thin-film transistor layer, in which a plurality of first electrodes, a plurality of light-emitting functional layers, and a common second electrode are sequentially stacked corresponding to a plurality of subpixels constituting the display area, wherein in the light-emitting element layer formation step, ink is ejected from a coating head having a plurality of nozzles while moving the coating head, thereby forming the plurality of light-emitting functional layers by an inkjet method, wherein in the thin-film transistor layer formation step, alignment marks are formed on the outside of each of the plurality of display areas on the base substrate; and in the light-emitting functional layer formation step of forming the plurality of light-emitting functional layers, the base substrate is aligned using the alignment marks, the ink is ejected and applied so as to overlap the alignment marks, the applied coating film is inspected, and then the ink is ejected and applied while moving the coating head, thereby forming the plurality of light-emitting functional layers for the display areas corresponding to the alignment marks with the applied coating film.

2. A method for manufacturing a display device comprising: a thin-film transistor layer formation step of forming thin-film transistor layers in each of the multiple display areas defined on a base substrate; and a light-emitting element layer formation step of forming a light-emitting element layer on the thin-film transistor layer, in which a plurality of first electrodes, a plurality of light-emitting functional layers, and a common second electrode are sequentially stacked corresponding to a plurality of subpixels constituting the display area, wherein in the light-emitting element layer formation step, ink is ejected from a coating head having a plurality of nozzles while moving the coating head, thereby forming the plurality of light-emitting functional layers by an inkjet method, wherein in the thin-film transistor layer formation step, alignment marks are formed on the outside of each of the plurality of display areas on the base substrate, and in the light-emitting functional layer formation step of forming the plurality of light-emitting functional layers, the base substrate is aligned using the alignment marks, ink is ejected and applied so as to overlap the alignment marks, and then the ink is ejected and applied while moving the coating head, thereby forming the first layer of the plurality of light-emitting functional layers for the display area corresponding to the alignment marks with the applied coating film, A method for manufacturing a display device, comprising: a second step of firing the coating film applied in the first step; a third step of aligning the base substrate using the alignment marks, inspecting the fired coating film that overlaps the alignment marks, then dispensing and applying the ink so that it overlaps the alignment marks, dispensing and applying the ink while moving the application head, and forming the second layer of the plurality of light-emitting functional layers in the display area corresponding to the alignment marks with the applied coating film; and a fourth step of firing the coating film applied in the third step.

3. A method for manufacturing a display device comprising: a thin-film transistor layer formation step of forming thin-film transistor layers in each of the multiple display areas defined on a base substrate; and a light-emitting element layer formation step of forming a light-emitting element layer on the thin-film transistor layer, in which a plurality of first electrodes, a plurality of light-emitting functional layers, and a common second electrode are sequentially stacked corresponding to a plurality of subpixels constituting the display area, wherein in the light-emitting element layer formation step, ink is ejected from a plurality of nozzles while moving a coating head having a plurality of nozzles to form the plurality of light-emitting functional layers by an inkjet method, wherein in the thin-film transistor layer formation step, alignment marks are formed on the outside of each of the plurality of display areas on the base substrate. A method for manufacturing a display device, characterized in that, in the process of forming the plurality of light-emitting functional layers described above, when forming the plurality of first electrodes, a lower electrode is formed using the same material as the plurality of first electrodes so as to overlap with the alignment mark; when forming the plurality of light-emitting functional layers, a light-emitting functional portion is formed using the same material as the plurality of light-emitting functional layers so as to overlap with the alignment mark; when forming the second electrode, an upper electrode is formed using the same material as the second electrode so as to overlap with the alignment mark; and then the light-emitting functional portion is made to emit light via the lower electrode and the upper electrode for inspection.

4. A method for manufacturing a display device according to any one of claims 1 to 3, wherein the ink contains nanoparticles.

5. A method for manufacturing a display device according to any one of claims 1 to 4, characterized in that it comprises a sealing film formation step of forming a sealing film on the light-emitting layer after the light-emitting layer formation step.

6. A method for manufacturing a display device according to claim 5, characterized in that, after the sealing film forming step, the method further comprises a fragmentation step in which the base substrate and the layer formed on the base substrate are divided into individual pieces according to the display area.

7. A method for manufacturing a display device according to any one of claims 1 to 6, characterized in that at least one of the plurality of light-emitting functional layers is a quantum dot light-emitting diode layer.

Images