Display device and method for forming sealing layer

Abstract

This display device (1) comprises a sealing layer (6), wherein the sealing layer (6) includes: a base layer (8) comprising a first sealing layer (26) and a plurality of protrusion parts (8P) which each include at least one microparticle (7) provided on the surface of the first sealing layer (26); and a second sealing layer (27) provided so as to be in contact with the protrusion part (8P) side of the base layer (8).

Description

Display device and method for forming encapsulation layer

[0001] The present disclosure relates to a display device including a plurality of light-emitting elements and a method for forming a sealing layer above the plurality of light-emitting elements.

[0002] In recent years, various display devices equipped with light-emitting elements have been developed, and in particular, display devices equipped with OLEDs (Organic Light Emitting Diodes) or QLEDs (Quantum dot Light Emitting Diodes) have attracted much attention because of their ability to achieve low power consumption, thinness, high image quality, and the like.

[0003] Patent document 1 describes a display device in which a sealing layer including a first inorganic barrier layer, an organic barrier layer, and a second inorganic barrier layer provided on a plurality of light-emitting elements suppresses reflection of light emitted from the light-emitting elements at the interface between the first inorganic barrier layer and the organic barrier layer in the sealing layer.

[0004] WO2019 / 186824 A1

[0005] Patent Document 1 describes that, for the purpose of suppressing reflection, the surface of the first inorganic barrier layer on the organic barrier layer side is roughened by increasing the temperature of a substrate including a light-emitting element, increasing plasma energy, or ashing the first inorganic barrier layer, and the maximum height Rz of the surface roughness is set to 20 nm or more and less than 100 nm.

[0006] However, the first inorganic barrier layer and the organic barrier layer are inherently prone to peeling, and when the maximum height Rz of the surface roughness at which the effect of suppressing reflection of visible light is obtained is in the range of approximately 20 nm or more and less than 100 nm, this tendency to peel cannot be improved at all, and the first inorganic barrier layer and the organic barrier layer still peel easily, resulting in reliability problems.

[0007] Furthermore, when the temperature of the substrate including the light-emitting element is increased or the plasma energy is increased, there is a problem that the light-emitting element may be damaged due to the influence of gases containing oxygen, etc., when the first inorganic barrier layer is ashed due to the increase in temperature.

[0008] One aspect of the present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a display device and a method for forming a sealing layer that can improve reliability without damaging light-emitting elements.

[0009] In order to solve the above-mentioned problems, the display device of the present disclosure comprises a plurality of light-emitting elements and a sealing layer provided above the plurality of light-emitting elements, wherein the sealing layer comprises a first sealing layer, a base layer provided with a plurality of protrusions each including at least one microparticle provided on the surface of the first sealing layer, and a second sealing layer provided so as to be in contact with the protrusion side of the base layer.

[0010] In order to solve the above-mentioned problems, the method for forming a sealing layer of the present disclosure is a method for forming a sealing layer as a layer above a plurality of light-emitting elements, and includes the steps of: forming a base layer having a first sealing layer and a plurality of protrusions, each of which includes at least one microparticle provided on the surface of the first sealing layer; and forming a second sealing layer so as to be in contact with the protrusion side of the base layer.

[0011] One embodiment of the present disclosure can provide a display device and a method for forming a sealing layer that can improve reliability without damaging light-emitting elements.

[0012] 1 is a plan view showing a schematic configuration of a display device of embodiment 1. FIG. 2 is a cross-sectional view showing a schematic configuration of a display region of the display device of embodiment 1. FIG. 3 is a cross-sectional view showing a schematic configuration of a portion of a sealing layer provided in the display device of embodiment 1. FIG. 4 is a cross-sectional view showing a schematic configuration of a sealing layer provided in the display device of embodiment 1. FIG. 5 is a diagram showing a schematic thickness of a portion of a sealing layer provided in the display device of embodiment 1. FIG. 6 is a plan view showing a schematic configuration of a mother substrate including a plurality of display devices shown in FIG. 7. FIG. 8 is a diagram showing an example of a process for forming microparticles contained in a sealing layer provided in the display device of embodiment 1. FIG. 9 is a diagram showing an example of a method for forming a sealing layer provided in the display device of embodiment 1. FIG. 10 is a diagram showing another example of a method for forming a sealing layer provided in the display device of embodiment 1. FIG. 11 is a cross-sectional view showing a schematic configuration of a portion of a sealing layer provided in the display device of embodiment 2. FIG. 12 is a plan view showing a schematic configuration of a display device of embodiment 3. FIG. 13 is a plan view showing a schematic configuration of a display device of embodiment 4. FIG. 14 is a cross-sectional view showing a schematic configuration of a portion of a sealing layer provided in the display device of embodiment 5. FIG. 15 is a cross-sectional view showing a schematic configuration of a portion of a sealing layer provided in the display device of embodiment 5. FIG. 16 is a cross-sectional view showing a schematic configuration of a portion of a sealing layer provided in the display device of embodiment 6. 10A and 10B are diagrams for explaining problems with a sealing layer provided in a display device that is a comparative example.

[0013] The following describes an embodiment of the present invention with reference to Figures 1 to 16. For the sake of convenience, components having the same functions as those described in a specific embodiment will be denoted by the same reference numerals, and their description may be omitted.

[0014] First Embodiment FIG. 1 is a plan view showing a schematic configuration of a display device 1 according to a first embodiment.

[0015] As shown in FIG. 1 , the display device 1 includes a non-display area NDA and a display area DA. Although not shown, a terminal portion is further provided outside the non-display area NDA. The display area DA of the display device 1 includes a plurality of pixels PIX, each of which includes a red sub-pixel RSP, a green sub-pixel GSP, and a blue sub-pixel BSP. In this embodiment, a case where one pixel PIX is configured with a red sub-pixel RSP, a green sub-pixel GSP, and a blue sub-pixel BSP will be described as an example, but this is not limiting. For example, one pixel PIX may include sub-pixels of other colors in addition to the red sub-pixel RSP, the green sub-pixel GSP, and the blue sub-pixel BSP.

[0016] FIG. 2 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 1 of the first embodiment.

[0017] As shown in Figure 2, in the display area DA of the display device 1, a barrier layer 3, a thin film transistor layer 4 including a transistor TR, a red light-emitting element 5R, a green light-emitting element 5G, a blue light-emitting element 5B and a bank 23, a sealing layer 6, and a functional film 39 are provided on a substrate 12 in this order from the substrate 12 side.

[0018] The red sub-pixel RSP provided in the display area DA of the display device 1 includes a red light-emitting element 5R, the green sub-pixel GSP provided in the display area DA of the display device 1 includes a green light-emitting element 5G, and the blue sub-pixel BSP provided in the display area DA of the display device 1 includes a blue light-emitting element 5B.

[0019] The substrate 12 may be, for example, a resin substrate made of a resin material such as polyimide, or a glass substrate. In this embodiment, since the display device 1 is a flexible display device, a case where a resin substrate made of a resin material such as polyimide is used as the substrate 12 will be described as an example, but this is not limiting. If the display device 1 is a non-flexible display device, a glass substrate can be used as the substrate 12.

[0020] The barrier layer 3 is a layer that prevents foreign substances such as water and oxygen from penetrating into the transistor TR, the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B, and can be composed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film of these, formed by the CVD method.

[0021] The transistor TR portion of the thin film transistor layer 4 including the transistor TR includes the semiconductor film SEM and doped semiconductor films SEM′ and SEM″, an inorganic insulating film 16, a gate electrode G, an inorganic insulating film 18, an inorganic insulating film 20, a source electrode S and a drain electrode D, and a planarization film 21, and the portion of the thin film transistor layer 4 including the transistor TR other than the transistor TR portion includes the inorganic insulating film 16, the inorganic insulating film 18, the inorganic insulating film 20, and the planarization film 21.

[0022] The semiconductor films SEM, SEM', and SEM'' may be made of, for example, low-temperature polysilicon (LTPS) or an oxide semiconductor (for example, an In-Ga-Zn-O based semiconductor). In this embodiment, the case where the transistor TR has a top-gate structure will be described as an example, but the present invention is not limited to this, and the transistor TR may also have a bottom-gate structure.

[0023] The gate electrode G and the source electrode S and drain electrode D can be formed of a single layer or a multilayer film of a metal containing at least one of aluminum, tungsten, molybdenum, tantalum, chromium, titanium, and copper, for example.

[0024] The inorganic insulating films 16, 18 and 20 can be formed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film of these films, which are formed by the CVD method.

[0025] The planarizing film 21 can be made of a coatable organic material such as polyimide or acrylic.

[0026] The red light-emitting element 5R included in the red subpixel RSP includes a first electrode 22 above the planarization film 21, a functional layer 24R including a red light-emitting layer, and a second electrode 25 above the first electrode 22. The green light-emitting element 5G included in the green subpixel GSP includes a first electrode 22 above the planarization film 21, a functional layer 24G including a green light-emitting layer, and a second electrode 25 above the first electrode 22. The blue light-emitting element 5B included in the blue subpixel BSP includes a first electrode 22 above the planarization film 21, a functional layer 24B including a blue light-emitting layer, and a second electrode 25 above the first electrode 22. Note that the insulating bank 23 covering the edge of the first electrode 22 can be formed by applying an organic material such as polyimide or acrylic and then patterning it by photolithography.

[0027] In this embodiment, the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B are described as being QLEDs (quantum dot light-emitting diodes) as an example, but this is not limited to this, and the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B may be OLEDs (organic light-emitting diodes), or further, some of the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B may be QLEDs, and the remaining parts of the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B may be OLEDs.

[0028] When the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B are QLEDs, the light-emitting layers of the light-emitting elements of each color contain quantum dots (QDs). The surface of each quantum dot (QD) may be provided with an organic ligand, for example, made of organic molecules, having a certain length to prevent aggregation of the quantum dots (QDs). The quantum dots (QDs) may have, for example, a core structure, a core / shell structure, a core / shell / shell structure, or a shell structure with a continuously changing core / shell ratio. When the quantum dots (QDs) have a core structure, for example, an organic ligand is provided on the surface of the core, and when the quantum dots (QDs) have a structure with a shell, for example, an organic ligand is provided on the surface of the shell. The core portion can be composed of, for example, Si, C, etc. in the case of a unicomponent system; for example, CdSe, CdS, CdTe, InP, GaP, InN, ZnSe, ZnS, ZnTe, etc. in the case of a ternary system; for example, CdSeTe, GaInP, ZnSeTe, etc. in the case of a quaternary system; for example, AIGS, etc. The shell portion can be composed of, for example, CdS, CdTe, CdSe, ZnS, ZnSe, ZnTe, etc. in the case of a ternary system; for example, CdSSe, CdTeSe, CdSTe, ZnSSe, ZnSTe, ZnTeSe, AIP, etc. Note that quantum dots (QDs) refer to dots with a maximum width of 100 nm or less. The shape of the quantum dots (QDs) is not particularly limited as long as it satisfies the above-mentioned maximum width, and is not limited to a spherical three-dimensional shape (circular cross-sectional shape). For example, the shape may be a polygonal cross-sectional shape, a rod-like three-dimensional shape, a branch-like three-dimensional shape, a three-dimensional shape with an uneven surface, or a combination thereof.

[0029] When the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B are OLEDs, the light-emitting layer of each light-emitting element contains an organic light-emitting material. The organic light-emitting material contained in the light-emitting layer can be formed by, for example, a vapor deposition method.

[0030] Control circuits including transistors TR that control the red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B are provided in the thin-film transistor layer 4 including transistors TR for each of the red sub-pixels RSP, green sub-pixels GSP, and blue sub-pixels BSP. The control circuits including transistors TR and the light-emitting elements provided for each of the red sub-pixels RSP, green sub-pixels GSP, and blue sub-pixels BSP are collectively referred to as sub-pixel circuits.

[0031] 2 may be of either a top-emission type or a bottom-emission type. When the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B have a stack structure in which, from the substrate 12 side, an anode (first electrode 22), functional layers 24R, 24G, and 24B, and a cathode (second electrode 25) are formed in this order, the cathode (second electrode 25) is disposed above the anode (first electrode 22). Therefore, to achieve a top-emission type, the anode (first electrode 22) may be formed from an electrode material that reflects visible light, and the cathode (second electrode 25) may be formed from an electrode material that transmits visible light. On the other hand, to achieve a bottom-emission type, the anode (first electrode 22) may be formed from an electrode material that transmits visible light, and the cathode (second electrode 25) may be formed from an electrode material that reflects visible light. On the other hand, when the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B have an inverted stack structure in which, from the substrate 12 side, a cathode as the first electrode 22, functional layers 24R, 24G, and 24B, and an anode as the second electrode 25 are formed in this order, the anode as the second electrode 25 is arranged as an upper layer than the cathode as the first electrode 22. Therefore, to achieve a top emission type, the cathode as the first electrode 22 can be formed from an electrode material that reflects visible light, and the anode as the second electrode 25 can be formed from an electrode material that transmits visible light. To achieve a bottom emission type, the cathode as the first electrode 22 can be formed from an electrode material that transmits visible light, and the anode as the second electrode 25 can be formed from an electrode material that reflects visible light.

[0032] The electrode material that reflects visible light is not particularly limited as long as it can reflect visible light and has electrical conductivity. Examples of the electrode material that reflects visible light include metal materials such as Al, Mg, Li, and Ag, alloys of the metal materials, laminates of the metal materials and transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), and laminates of the alloys and the transparent metal oxides.

[0033] On the other hand, the electrode material that transmits visible light is not particularly limited as long as it can transmit visible light and has conductivity, and examples thereof include transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), thin films made of metal materials such as Al and Ag, and nanowires made of metal materials such as Al and Ag.

[0034] The sealing layer 6 is a light-transmitting film that prevents foreign substances such as water and oxygen from penetrating into the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B.

[0035] The functional film 39 is a film having at least one of an optical compensation function, a touch sensor function, and a protection function, for example.

[0036] Fig. 3 is a cross-sectional view showing a schematic configuration of some layers of the sealing layer 6 provided in the display device 1 of embodiment 1. The display device 1a shown in Fig. 3 is a display device in a state before the third sealing layer 28 and the functional film 39 provided in the display device 1 of embodiment 1 shown in Fig. 2 are provided. Fig. 4 is a cross-sectional view showing a schematic configuration of the sealing layer 6 provided in the display device 1 of embodiment 1. The display device 1b shown in Fig. 4 is a display device in a state before the functional film 39 provided in the display device 1 of embodiment 1 shown in Fig. 2 is provided.

[0037] As shown in Fig. 2, the display device 1 includes a red light-emitting element 5R, a green light-emitting element 5G, and a blue light-emitting element 5B. In the display device 1, the sealing layer 6 provided above the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B shown in Fig. 2 includes a first sealing layer 26, an underlayer 8 including a plurality of protrusions 8P each including at least one microparticle 7 provided on the surface of the first sealing layer 26, i.e., on the upper surface of the first sealing layer 26 facing the second sealing layer 27, and a second sealing layer 27 provided in contact with the protrusions 8P side of the underlayer 8, as shown in Fig. 3. As described above, in the display device 1, the underlayer 8 provided as part of the sealing layer 6 includes a plurality of protrusions 8P including at least relatively large microparticles 7. This increases the contact area between the underlayer 8 and the second sealing layer 27, thereby improving adhesion, thereby preventing the second sealing layer 27 provided in contact with the protrusions 8P side of the underlayer 8 from peeling off from the underlayer 8. Furthermore, as will be described later, the microparticles 7 contained in the base layer 8 can be formed without damaging the red light-emitting elements 5R, the green light-emitting elements 5G, and the blue light-emitting elements 5B. Therefore, a display device 1 can be realized that can improve reliability without damaging the light-emitting elements. Note that in this embodiment, as shown in FIG. 3 , a case will be described as an example in which the microparticles 7 and the second sealing layer 27 are provided so that a plurality of protrusions 8P provided on the surface of the first sealing layer 26, i.e., on the upper surface of the first sealing layer 26 facing the second sealing layer 27, overlap with the second sealing layer 27 in a planar view. However, the present invention is not limited to this.

[0038] As shown in FIG. 1 , the display device 1 includes a display area DA and a non-display area NDA outside the display area DA. In this embodiment, as shown in FIG. 3 , a frame-shaped first bank 30 is provided in the non-display area NDA. The display area DA is an area inside the first bank 30, and the multiple protrusions 8P of the underlayer 8 are provided only in the display area DA. Note that in FIGS. 3 , 4 , 10 , 13 , 14 , 15 , and 16 , the display area DA is schematically illustrated as an area extending from the inner edge of the first bank 30. However, as described above, the display area DA is an area inside the first bank 30. In this embodiment, the second sealing layer 27 is also provided only in the display area DA, and the second sealing layer 27 covers the multiple protrusions 8P of the underlayer 8. Therefore, as shown in the enlarged view of portion A in FIG. 3 , neither the microparticles 7 nor the second sealing layer 27 are formed on the first sealing layer 26 provided in the non-display area DA. In this embodiment, as shown in FIG. 3 , some of the multiple protrusions 8P of the underlayer 8 are provided along the inner inclined surface of the first bank 30 (the inclined surface on the left side of the first bank 30 in FIG. 3 ), but this is not limited thereto. In this embodiment, the first sealing layer 26 is provided over the entire display area DA and the entire non-display area NDA, as shown in FIG. 3 . Preferably, the first sealing layer 26 is an inorganic film and the second sealing layer 27 is an organic film. In this embodiment, the first sealing layer 26 is an inorganic film and the second sealing layer 27 is an organic film. For example, if a relatively large foreign substance having a thickness equal to or greater than the thickness of the first sealing layer 26 is mixed into the first sealing layer 26, outside air will infiltrate through the interface with the foreign substance. However, if the second sealing layer 27 is an organic film, the second sealing layer 27 can be formed thicker, thereby covering the foreign substance and preventing outside air from infiltrating through the interface with the foreign substance. The microparticles 7 may be made of an inorganic material, an organic material, or a mixture of an organic material and an inorganic material. In this embodiment, however, microparticles 7 made of an inorganic material, for example, silicon nitride, are used.

[0039] In this embodiment, as shown in FIG. 4 , a third sealing layer 28 composed of an inorganic film covering at least the second sealing layer 27 is provided as a continuous film over the entire display area DA and the entire non-display area NDA. The first sealing layer 26 composed of an inorganic film is also provided as a continuous film over the entire display area DA and the entire non-display area NDA. The first sealing layer 26 and the third sealing layer 28 are in contact in the non-display area NDA. Note that a continuous film refers to a single, uninterrupted film. As shown in the enlarged view of portion B in FIG. 4 , there are no microparticles 7 between the first sealing layer 26 and the second sealing layer 27 in the non-display area DA. This suppresses reflection of external light L1 in the non-display area DA, thereby realizing a display device 1 with a good appearance in the non-display area DA. Furthermore, as shown in FIG. 4 , the second sealing layer 27 composed of an organic film can be enclosed by the first sealing layer 26 composed of an inorganic film and the third sealing layer 28 composed of an inorganic film, thereby realizing a display device 1 that further suppresses the intrusion of external air. 4 is larger than the second sealing layer 27 shown in Fig. 4 in a plan view, and the third sealing layer 28 shown in Fig. 4 is larger than the second sealing layer 27 in a plan view and covers at least the second sealing layer 27. As shown in Fig. 4, multiple protrusions 8P of the base layer 8 are provided only between the first sealing layer 26 and the second sealing layer 27, and the first sealing layer 26 and the third sealing layer 28 are in contact with each other in an area where the second sealing layer 27 is not provided. Note that, as shown in Fig. 4, some of the multiple protrusions 8P of the base layer 8 provided between the first sealing layer 26 and the second sealing layer 27 may be provided along the inner inclined surface of the first bank 30.

[0040] In this embodiment, the first sealing layer 26 is a laminated film formed by CVD, in which a silicon oxide film (e.g., 20 nm thick), a silicon oxynitride film (e.g., 1100 nm thick), and a silicon nitride film (e.g., 100 nm thick) are stacked in this order from the substrate 12 (shown in FIG. 2 ), but this is not limiting. The second sealing layer 27 is an acrylic resin (e.g., 10,000 nm thick) formed using a drop-type device, such as an inkjet device, but this is not limiting. A light-transmitting organic film other than acrylic resin may also be used, and the second sealing layer 27 may be formed using, for example, a spin coater or a slit coater. The third sealing layer 28 is a single-layered silicon nitride film (e.g., 500 nm thick) formed by CVD, but this is not limiting.

[0041] FIG. 16 is a diagram for explaining a problem with the sealing layer provided in the display device 100 as a comparative example.

[0042] 16 , in the case of display device 100, which is a comparative example, the sealing layer includes a structure in which second sealing layer 27 is simply laminated directly on first sealing layer 26. Therefore, the adhesion between first sealing layer 26 and second sealing layer 27 is not very strong, and first sealing layer 26 and second sealing layer 27 peel off while display device 100 is being used. Therefore, there is a problem that the long-term reliability of display device 100 cannot be ensured. Furthermore, in recent years, in the field of flexible display devices, the bending diameter of display devices has become smaller, and in the case of a sealing layer including a structure such as that shown in FIG. 16 , first sealing layer 26 and second sealing layer 27 may peel off in a relatively short time, which is a problem that short-term reliability cannot be ensured.

[0043] FIG. 5 is a diagram schematically showing the thickness of some layers of the sealing layer 6 provided in the display device 1 of the first embodiment.

[0044] As shown in Figure 5, in the display device 1, the base layer 8 provided as part of the sealing layer 6 has multiple protrusions 8P containing relatively large microparticles 7.Therefore, by increasing the contact area between the base layer 8 and the second sealing layer 27 and improving adhesion, the second sealing layer 27, which is provided in contact with the protrusions 8P side of the base layer 8, is prevented from peeling off from the base layer 8.

[0045] The maximum length of the microparticles 7 is preferably 5% to 10% of the thickness of the maximum thickness portion of the second sealing layer 27. As shown in FIG. 5 , the thickness of the maximum thickness portion of the second sealing layer 27 is the sum of heights H1 and H3, and the maximum length of the microparticles 7 is the value of height H1. The thickness of the first sealing layer 26 is the value of height H2, and the height from the bottom surface of the base layer 8 to the apex of the protrusion 8P is the value of height H1 and height H2. For example, if the thickness of the maximum thickness portion of the second sealing layer 27, i.e., the sum of heights H1 and H3, is 10 μm, the maximum length of the microparticles 7, i.e., the value of height H1, is preferably 0.5 μm to 1 μm. In this embodiment, spherical microparticles with a diameter of 0.5 μm to 1 μm are used as the microparticles 7. However, the shape of the microparticles is not particularly limited as long as protrusions 8P containing at least the microparticles 7 can be formed.

[0046] 3, 4, and 5, the case where the base layer 8 is composed of the first sealing layer 26 and a plurality of microparticles 7 provided directly on the first sealing layer 26 will be described as an example, but the present invention is not limited to this. For example, although not shown, the base layer 8 may be composed of the first sealing layer 26, a plurality of microparticles 7 provided directly on the first sealing layer 26, and an additional layer of the first sealing layer 26 provided directly on the first sealing layer 26 and the plurality of microparticles 7. The additional layer of the first sealing layer 26 is a layer formed after the plurality of microparticles 7 are provided on the first sealing layer 26. For example, the base layer 8 may be composed of a first sealing layer 26 composed of a laminated film of a silicon oxide film (e.g., 20 nm thick) and a silicon oxynitride film (e.g., 1100 nm thick), a plurality of microparticles 7 provided directly on the laminated film, and an additional layer of the first sealing layer 26 composed of a silicon nitride film (e.g., 100 nm thick) provided directly on the laminated film and the plurality of microparticles 7. As described above, in this embodiment, spherical microparticles having a diameter of 0.5 μm or more and 1 μm or less are used as the microparticles 7, and the thickness of the silicon nitride film, which is the additional layer of the first sealing layer 26, is, for example, 100 nm. Therefore, the microparticles 7 are not covered by the silicon nitride film, which is the additional layer of the first sealing layer 26, and protrusions 8P including at least the microparticles 7 can be formed.

[0047] FIG. 6 is a plan view showing a schematic configuration of a motherboard 60 including a plurality of display devices 1b shown in FIG.

[0048] As shown in Fig. 6, the mother substrate 60 includes a plurality of display devices 1b in a state before the provision of the functional film 39 provided on the display device 1 of embodiment 1 shown in Fig. 2. After the plurality of display devices 1b included in the mother substrate 60 shown in Fig. 6 are diced into individual pieces, the functional film 39 is provided for each of the diced display devices 1b, thereby obtaining the display device 1 shown in Figs.

[0049] FIG. 7 is a diagram showing an example of a process for forming the microparticles 7 contained in the sealing layer 6 provided in the display device 1 of the first embodiment.

[0050] In this embodiment, the microparticles 7 are made of silicon nitride formed using an RF (radio frequency) plasma CVD apparatus. As shown in FIG. 7, the source gas is, for example, SiH ４ and NH ３ And, H ２ And, N ２and are supplied. By supplying the material gas and turning on the RF (radio frequency) plasma, activated species of the material gas are formed. Then, by stopping the supply of the material gas and turning off the RF (radio frequency) plasma, the activated species of the material gas become microparticles 7 and adhere to the first sealing layer 26. The size of the microparticles 7 can be controlled by the number of times the supply of the material gas and the RF (radio frequency) plasma are turned on and off. The method of forming the microparticles 7 using the RF (radio frequency) plasma CVD apparatus can be performed at a relatively low temperature. In this embodiment, an example will be described in which the microparticles 7 are formed using the RF (radio frequency) plasma CVD apparatus after the first sealing layer 26 is formed. However, as described above, after forming the stacked film of the silicon oxide film and the silicon oxynitride film of the first sealing layer 26, the microparticles 7 may be formed using the RF (radio frequency) plasma CVD apparatus, and then a silicon nitride film may be formed as an additional layer of the first sealing layer 26. Thus, if a silicon nitride film, which is an additional layer of the first sealing layer 26, is formed after the microparticles 7 are formed, the microparticles 7 can be further adhered to the stacked film of the silicon oxide film and silicon oxynitride film, which is the first sealing layer 26. In this embodiment, as shown in FIGS. 3 and 4 , the multiple protrusions 8P of the underlayer 8 are provided only in the display area DA. Therefore, by using a mask having openings only in the display area DA and supplying the material gas only to the display area DA, the microparticles 7 can be formed only on the first sealing layer 26 provided in the display area DA. As described above, when forming the microparticles 7 using an RF (radio frequency) plasma CVD apparatus, the region where the microparticles 7 are to be formed can be relatively easily defined using a mask. Furthermore, in this embodiment, a parallel-plate RF (radio frequency) plasma CVD apparatus was used, which includes flat plates 70a and 70b arranged parallel to each other, as shown in FIG. 7 , but the present invention is not limited thereto.Although the case where the microparticles 7 are formed on the first sealing layer 26 or on a portion of the first sealing layer 26 using an RF (radio frequency) plasma CVD apparatus has been described as an example here, the microparticles 7 may be formed on the first sealing layer 26 or on a portion of the first sealing layer 26 by, for example, applying a dispersion solution of a plurality of microparticles of a predetermined size, as long as the microparticles 7 can be formed without damaging the light-emitting element. When using the method of applying a dispersion solution of a plurality of microparticles of a predetermined size, the frame-shaped first bank 30 or the frame-shaped second bank 31 is used, and the dispersion solution of microparticles is dripped only inside the frame-shaped first bank 30 or only inside the frame-shaped second bank 31, thereby forming the microparticles 7 only on the entire inside of the frame-shaped first bank 30 or only inside the frame-shaped second bank 31.

[0051] Fig. 8 is a diagram showing an example of a method for forming the sealing layer 6 provided in the display device 1 of embodiment 1. Fig. 9 is a diagram showing another example of a method for forming the sealing layer 6 provided in the display device 1 of embodiment 1.

[0052] 8 and 9 is a method of forming the sealing layer 6 provided in the display device 1 as a layer above the red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B provided in the display device 1, and includes the steps of forming a first sealing layer 26 and an underlayer 8 including a plurality of protrusions 8P each including at least one microparticle 7 provided on the surface of the first sealing layer 26, i.e., on the upper surface of the first sealing layer 26 facing the second sealing layer 27, and forming the second sealing layer 27 so as to contact the protrusion 8P side of the underlayer 8. This method of forming the sealing layer 6 can improve reliability without damaging the light-emitting elements.

[0053] 8 , the method for forming the sealing layer 6 of the display device 1 includes a step S11 of forming a base layer 8 having a plurality of protrusions 8P including at least microparticles 7, and a step S12 of forming a plurality of microparticles 7 on the first sealing layer 26, which is performed after the step S11 of forming the first sealing layer 26. The method for forming the sealing layer 6 of the display device 1 also includes a step S13 of forming a second sealing layer 27, which is performed after the step of forming the base layer 8 having a plurality of protrusions 8P including at least microparticles 7, and a step S14 of forming a third sealing layer 28, which is performed after the step S13 of forming the second sealing layer 27. In the step S13 of forming the second sealing layer 27, the second sealing layer 27 may be formed using a drop-type device, for example, an inkjet device. According to the method for forming the sealing layer 6 provided in the display device 1 shown in Figure 8, the microparticles 7 are formed after the first sealing layer 26 is completely formed, that is, in this embodiment, after the three layers that make up the first sealing layer 26 are completely formed, thereby further reducing damage to the light-emitting element.

[0054] 9 , in another method for forming the sealing layer 6 of the display device 1, the step of forming the base layer 8 having a plurality of protrusions 8P including at least microparticles 7 may include step S21 of forming a first sealing layer 26, step S22 of forming a plurality of microparticles 7 on the first sealing layer 26, and step S23 of forming an additional layer of the first sealing layer directly on the first sealing layer 26 and the plurality of microparticles 7. The other method for forming the sealing layer 6 of the display device 1 also includes step S24 of forming a second sealing layer 27, which is performed after the step of forming the base layer 8 having a plurality of protrusions 8P including at least microparticles 7, and step S25 of forming a third sealing layer 28, which is performed after step S24 of forming the second sealing layer 27. In step S24 of forming the second sealing layer 27, the second sealing layer 27 may be formed using a drop-type device, such as an inkjet device. According to another method for forming the encapsulation layer 6 provided in the display device 1 shown in FIG. 9, the microparticles 7 can be further adhered to the first encapsulation layer 26 by adding an additional layer of the first encapsulation layer.

[0055] 10 is a cross-sectional view showing a schematic configuration of some layers of a sealing layer provided in a display device of embodiment 2. Note that the display device 10a shown in Fig. 10 is a display device in a state before the third sealing layer 28 and the functional film 39 provided in the display device of embodiment 2 are provided.

[0056] In the display device 1 of the first embodiment described above, the first sealing layer 26 made of an inorganic film is provided as a continuous film over the entire display area DA and the entire non-display area NDA, as shown in Figures 3 and 4. However, in this embodiment, as shown in Figure 10, the first sealing layer 26 made of an inorganic film is provided as a continuous film only in the display area DA. Furthermore, the third sealing layer 28 made of an inorganic film that covers at least the second sealing layer 27 is provided as a continuous film over the entire display area DA and the entire non-display area NDA, as shown in Figure 4, similar to the display device 1 of the first embodiment. Therefore, in the sealing layers provided in the display device of the second embodiment, the first sealing layer 26 and the third sealing layer 28 are in contact at the edge of the display area DA. In the display device of the second embodiment, the second sealing layer 27 made of an organic film can also be covered by the first sealing layer 26 made of an inorganic film and the third sealing layer 28 made of an inorganic film, thereby further suppressing the intrusion of outside air. Furthermore, in the sealing layer provided in the display device of embodiment 2, the area where the first sealing layer 26 is formed and the area where the microparticles 7 are formed coincide with each other, so the first sealing layer 26 and the microparticles 7 can be formed using the same mask.

[0057] Third Embodiment FIG. 11 is a plan view showing a schematic configuration of a display device 29 according to a third embodiment.

[0058] As shown in FIG. 11 , the display device 29 is a flexible display device and has a folding line FL1 along which the flexible display device is primarily folded. The display device 29 includes a display area DA and a non-display area NDA located outside the display area DA. As shown in FIGS. 3 and 4 , the non-display area NDA includes a frame-shaped first bank 30 and a frame-shaped second bank 31 located outside the first bank 30. The display area DA is located inside the first bank 30. As shown in FIG. 11 , the plurality of protrusions 8P of the base layer 8 may be provided in an island-like pattern along the folding line FL1 in a portion of the display area DA and in at least a portion of the area inside the second bank 31 in the non-display area NDA. In this embodiment, two protrusions 8P of the base layer 8 are provided in an island-like pattern in the first region RE1 and the second region RE2 in FIG. 11 . Furthermore, in the display device 29 of embodiment 3, the second sealing layer 27 is provided only in the region inside the second bank 31 (similar to the second sealing layer 27 in FIG. 15 ), and the second sealing layer 27 covers the plurality of protrusions 8P of the base layer 8. Some of the plurality of protrusions 8P of the base layer 8 may be provided along each of the inner inclined surfaces of the second bank 31 (see FIG. 15 ). According to the display device 29 of embodiment 3, peeling of the second sealing layer 27, which may occur in a portion where the display device 29 is frequently bent, can be efficiently suppressed.

[0059] In display device 29 of embodiment 3, third sealing layer 28, which is made of an inorganic film and covers at least second sealing layer 27, is provided as a continuous film over the entire display area DA and the entire non-display area NDA, and first sealing layer 26, which is made of an inorganic film, is also provided as a continuous film over the entire display area DA and the entire non-display area NDA, so that first sealing layer 26 and third sealing layer 28 are in contact with each other in an area where second sealing layer 27 is not provided. Therefore, in display device 29 of embodiment 3, second sealing layer 27, which is made of an organic film, can be covered with first sealing layer 26, which is made of an inorganic film, and third sealing layer 28, which is also made of an inorganic film, thereby further suppressing the intrusion of outside air.

[0060] Fourth Embodiment FIG. 12 is a plan view showing a schematic configuration of a display device 38 according to a fourth embodiment.

[0061] As shown in FIG. 12 , the display device 38 is a flexible display device and has a folding line FL1 along which the flexible display device is primarily folded. The display device 38 includes a display area DA and a non-display area NDA located outside the display area DA. As shown in FIGS. 3 and 4 , the non-display area NDA includes a frame-shaped first bank 30 and a frame-shaped second bank 31 located outside the first bank 30. The display area DA is located inside the first bank 30. As shown in FIG. 12 , multiple protrusions 8P of the base layer 8 may be linearly arranged along the folding line FL1 in a portion of the display area DA and at least a portion of the area inside the second bank in the non-display area NDA. In this embodiment, the multiple protrusions 8P of the base layer 8 are arranged in a third region RE3 in FIG. 12 . Furthermore, in the display device 38 of embodiment 4, the second sealing layer 27 is provided only in the region inside the second bank 31 (similar to the second sealing layer 27 in FIG. 15 ), and the second sealing layer 27 covers the multiple protrusions 8P of the base layer 8. Some of the multiple protrusions 8P of the base layer 8 may be provided along each of the inner inclined surfaces of the second bank 31 (see FIG. 15 ). According to the display device 38 of embodiment 4, peeling of the second sealing layer 27, which may occur in areas where the display device 38 is frequently bent, can be efficiently suppressed.

[0062] In the display device 38 of the fourth embodiment, the third sealing layer 28, which is made of an inorganic film and covers at least the second sealing layer 27, is provided as a continuous film over the entire display area DA and the entire non-display area NDA, and the first sealing layer 26, which is made of an inorganic film, is also provided as a continuous film over the entire display area DA and the entire non-display area NDA, so that the first sealing layer 26 and the third sealing layer 28 are in contact with each other in an area where the second sealing layer 27 is not provided. Therefore, in the display device 38 of the fourth embodiment, the second sealing layer 27, which is made of an organic film, can be covered with the first sealing layer 26, which is made of an inorganic film, and the third sealing layer 28, which is also made of an inorganic film, thereby further suppressing the intrusion of outside air.

[0063] [Embodiment 5] Fig. 13 is a cross-sectional view showing a schematic configuration of some layers of the sealing layer 6 provided in a display device of embodiment 5. A display device 40a shown in Fig. 13 is a display device in a state before the third sealing layer 28 and functional film 39 provided in the display device 1 of embodiment 1 shown in Fig. 2 are provided. Fig. 14 is a cross-sectional view showing a schematic configuration of the sealing layer 6 provided in the display device of embodiment 5. A display device 40b shown in Fig. 14 is a display device in a state before the functional film 39 provided in the display device 1 of embodiment 1 shown in Fig. 2 is provided.

[0064] 13 and 14 , in the display device of embodiment 5, the first sealing layer 26, which is made of an inorganic film, is provided as a continuous film over the entire display area DA and the entire non-display area NDA. The multiple protrusions 8P of the base layer 8 are provided over the entire display area DA and the entire non-display area NDA. The second sealing layer 27 is provided only over the entire display area DA. The third sealing layer 28, which is made of an inorganic film and covers at least the second sealing layer 27, is provided as a continuous film over the entire display area DA and the entire non-display area NDA. Therefore, as shown in the enlarged view of portion C in FIG. 13 , multiple protrusions 8P of the base layer 8 that are not covered by the second sealing layer 27, i.e., microparticles 7 that are not covered by the second sealing layer 27, are generated in the non-display area NDA. As shown in the enlarged view of portion E in FIG. 14 , the multiple protrusions 8P of the base layer 8 that are not covered by the second sealing layer 27 grow around the microparticles 7 as nuclei during the process of forming the third sealing layer 28, resulting in the formation of large particles AG. Therefore, in the non-display area NDA of the display device of embodiment 5, the visible light component of the external light L1 is scattered by the large particles AG, causing the non-display area NDA to appear cloudy. In this embodiment, the case where the microparticles 7 are provided over the entire display area DA and the entire non-display area NDA has been described as an example. However, even when the microparticles 7 are provided over the entire display area DA and a portion of the non-display area NDA, a portion of the non-display area NDA appears cloudy. This phenomenon of the non-display area NDA appearing cloudy can be solved by providing the display device of embodiment 5 with a shielding member that hides the non-display area NDA from the user. Therefore, in the display device of embodiment 5 that includes a shielding member that hides the non-display area NDA, in the process of forming the microparticles 7, it is no longer necessary to precisely align the area where the microparticles 7 are formed with the area where the second sealing layer 27 is formed, thereby limiting the area where the microparticles 7 are formed to only the display area DA, thereby widening the process margin in the process of forming the microparticles 7.

[0065] 15 is a cross-sectional view showing a schematic configuration of some layers of the sealing layer 6 provided in a display device of embodiment 6. A display device 50a shown in Fig. 15 is a display device in a state before the third sealing layer 28 and the functional film 39 provided in the display device 1 of embodiment 1 shown in Fig. 2 are provided.

[0066] 15 , in the display device of embodiment 6, a frame-shaped first bank 30 and a frame-shaped second bank 31 located outside the first bank 30 are provided in the non-display area NDA, and the display area DA is the area inside the first bank 30. As shown in Fig. 15 , the multiple protrusions 8P of the base layer 8 are provided only in the area inside the second bank 31, and the second sealing layer 27 is provided only in the area inside the second bank 31, and the second sealing layer 27 covers the multiple protrusions 8P of the base layer 8. As shown in Fig. 15 , some of the multiple protrusions 8P of the base layer 8 may be provided along each of the inner inclined surfaces of the second bank 31. Without being limited to this, for example, the multiple protrusion portions 8P of the base layer 8 may be provided only in the area inside the second bank 31 in the non-display area NDA, the second sealing layer 27 may be provided only in the area inside the second bank 31, and the second sealing layer 27 may cover the multiple protrusion portions 8P of the base layer 8.

[0067] In the display device of embodiment 6 as well, third sealing layer 28, which is made of an inorganic film and covers at least second sealing layer 27, is provided as a continuous film over the entire display area DA and the entire non-display area NDA, and first sealing layer 26, which is made of an inorganic film, is also provided as a continuous film over the entire display area DA and the entire non-display area NDA, so that first sealing layer 26 and third sealing layer 28 are in contact with each other in an area where second sealing layer 27 is not provided. Therefore, in the display device of embodiment 6 as well, second sealing layer 27, which is made of an organic film, can be covered with first sealing layer 26, which is made of an inorganic film, and third sealing layer 28, which is also made of an inorganic film, thereby further suppressing the intrusion of outside air.

[0068] [Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0069] The present invention can be used in a display device and a method for forming a sealing layer.

[0070] 1, 1a, 1b Display device 10a, 29, 38 Display device 40a, 40b, 50a Display device 5R Red light emitting element (light emitting element) 5G Green light emitting element (light emitting element) 5B Blue light emitting element (light emitting element) 6 Sealing layer 7 Microparticle 8 Underlayer 8P Protrusion 22 First electrode 23 Bank 24R Functional layer including red light emitting layer 24G Functional layer including green light emitting layer 24B Functional layer including blue light emitting layer 25 Second electrode 26 First sealing layer 27 Second sealing layer 28 Third sealing layer 30 First bank 31 Second bank DA Display area NDA Non-display area RE1 First area RE2 Second area RE3 Third area FL1 Bending line

Claims

1. A display device comprising: a plurality of light-emitting elements; and a sealing layer provided above the plurality of light-emitting elements, wherein the sealing layer comprises: a first sealing layer; a base layer having a plurality of protrusions, each of the protrusions including at least one microparticle provided on the surface of the first sealing layer; and a second sealing layer provided in contact with the protrusion side of the base layer.

2. The display device according to claim 1, wherein the plurality of protrusions provided on the surface of the first sealing layer overlap with the second sealing layer in a plan view.

3. The display device according to claim 1 or 2, wherein the first sealing layer is an inorganic film, and the second sealing layer is an organic film.

4. The display device according to any one of claims 1 to 3, wherein the maximum length of the microparticles is 0.5 µm or more and 1 µm or less.

5. The display device according to any one of claims 1 to 4, wherein the maximum length of the microparticles is 5% to 10% of the thickness of the maximum thickness portion of the second sealing layer.

6. The display device according to any one of claims 1 to 5, wherein the microparticles are made of an inorganic material.

7. The display device according to any one of claims 1 to 6, wherein the underlayer is composed of the first sealing layer and the plurality of microparticles provided directly on the first sealing layer.

8. A display device described in any one of claims 1 to 6, wherein the underlayer is composed of the first sealing layer, the plurality of microparticles provided directly on the first sealing layer, and an additional layer of the first sealing layer provided directly on the first sealing layer and the plurality of microparticles.

9. A display device according to any one of claims 1 to 8, comprising a display area and a non-display area outside the display area, a frame-shaped first bank being provided in the non-display area, the display area being an area inside the first bank, and the plurality of protrusions of the base layer being provided only in the display area.

10. The display device according to claim 9, wherein some of the plurality of protrusions of the underlayer are provided along the inner inclined surface of the first bank.

11. A display device according to claim 9 or 10, wherein the second sealing layer is provided only in the display area, and the second sealing layer covers the plurality of protrusions of the base layer.

12. A display device as described in claim 11, wherein a third sealing layer made of an inorganic film covering at least the second sealing layer is provided as a continuous film over the entire display area and the entire non-display area, the first sealing layer made of an inorganic film is provided as a continuous film over the entire display area and the entire non-display area, and the first sealing layer and the third sealing layer are in contact in the non-display area.

13. A display device as described in claim 11, wherein a third sealing layer made of an inorganic film covering at least the second sealing layer is provided as a continuous film over the entire display area and the entire non-display area, the first sealing layer made of an inorganic film is provided as a continuous film only over the entire display area, and the first sealing layer and the third sealing layer are in contact at the edge of the display area.

14. A display device as described in any one of claims 1 to 8, comprising a display area and a non-display area outside the display area, wherein the non-display area is provided with a frame-shaped first bank and a frame-shaped second bank located outside the first bank, wherein the display area is the area inside the first bank, wherein the multiple protrusions of the base layer are provided only in the area inside the second bank, wherein the second sealing layer is provided only in the area inside the second bank, and wherein the second sealing layer covers the multiple protrusions of the base layer.

15. A display device as described in any one of claims 1 to 8, comprising a display area and a non-display area outside the display area, wherein the non-display area is provided with a frame-shaped first bank and a frame-shaped second bank located outside the first bank, the display area is the area inside the first bank, the multiple protrusions of the base layer are provided only in the area inside the second bank in the non-display area, the second sealing layer is provided only in the area inside the second bank, and the second sealing layer covers the multiple protrusions of the base layer.

16. The display device according to any one of claims 1 to 8, wherein the display device is a flexible display device, and comprises a display area and a non-display area outside the display area, wherein the non-display area is provided with a frame-shaped first bank and a frame-shaped second bank located outside the first bank, wherein the display area is an area inside the first bank, wherein the multiple protrusions of the base layer are provided in a line along a folding line in part of the display area and in at least part of the area inside the second bank in the non-display area, and wherein the second sealing layer is provided only in the area inside the second bank, and wherein the second sealing layer covers the multiple protrusions of the base layer.

17. The display device according to any one of claims 1 to 8, wherein the display device is a flexible display device and comprises a display area and a non-display area outside the display area, wherein the non-display area is provided with a frame-shaped first bank and a frame-shaped second bank located outside the first bank, wherein the display area is an area inside the first bank, wherein the plurality of protrusions of the base layer are provided in an island shape along a folding line in part of the display area and in at least part of the area inside the second bank in the non-display area, and wherein the second sealing layer is provided only in the area inside the second bank, and wherein the second sealing layer covers the plurality of protrusions of the base layer.

18. The display device according to any one of claims 14 to 17, wherein some of the plurality of protrusions of the underlayer are provided along the inner inclined surface of the second bank.

19. A display device described in any one of claims 14 to 18, wherein a third sealing layer composed of an inorganic film covering at least the second sealing layer is provided as a continuous film over the entire display area and the entire non-display area, the first sealing layer composed of an inorganic film is provided as a continuous film over the entire display area and the entire non-display area, and the first sealing layer and the third sealing layer are in contact in areas where the second sealing layer is not provided.

20. A display device as described in any one of claims 1 to 7, wherein the first sealing layer is larger than the second sealing layer in a planar view, and a third sealing layer is provided which is larger than the second sealing layer in a planar view and covers at least the second sealing layer, the multiple protrusions of the base layer are provided only between the first sealing layer and the second sealing layer, and the first sealing layer and the third sealing layer are in contact in areas where the second sealing layer is not provided.

21. The display device according to any one of claims 1 to 20, wherein each of the plurality of light-emitting elements includes a light-emitting layer, and the light-emitting layer includes quantum dots.

22. The display device according to any one of claims 1 to 20, wherein each of the plurality of light-emitting elements includes a light-emitting layer, and the light-emitting layer includes an organic light-emitting material.

23. A method for forming a sealing layer above a plurality of light-emitting elements, the method comprising: forming a base layer having a first sealing layer and a plurality of protrusions, each of the protrusions including at least one microparticle provided on a surface of the first sealing layer; and forming a second sealing layer so as to contact the protrusion side of the base layer.

24. The method for forming an encapsulating layer according to claim 23, wherein the step of forming the underlayer comprises the steps of: forming the first encapsulating layer; and forming the plurality of microparticles on the first encapsulating layer.

25. The method for forming a sealing layer of claim 23, wherein the step of forming the underlayer includes the steps of: forming the first sealing layer; forming the plurality of microparticles on the first sealing layer; and forming an additional layer of the first sealing layer directly above the first sealing layer and the plurality of microparticles.

26. The method for forming an encapsulating layer according to claim 24 or 25, wherein in the step of forming the plurality of microparticles, the plurality of microparticles are formed using an RF (radio frequency) plasma CVD device.

27. The method for forming a sealing layer according to claim 24 or 25, wherein the step of forming the plurality of microparticles includes the step of applying a dispersion of the plurality of microparticles.

28. A method for forming a sealing layer according to any one of claims 23 to 27, wherein in the step of forming the second sealing layer, the second sealing layer is formed using a drop-type apparatus.

Images