Display device

Abstract

An organic EL display device (90a) has a display region (D) and a frame region (F) and is equipped with: a first substrate (60a) that is provided with a plurality of organic EL elements (35); a second substrate (80a) that is disposed in a manner of facing the first substrate; and a plurality of pixel spacers (50da) that are disposed in the display region (D), and a plurality of frame spacers (50fa) that are disposed in the frame region (F), the plurality of pixel spacers and the plurality of frame spacers being interposed between the two substrates (60a, 80a). The first substrate (60a) is sealed by the second substrate (80a) with the spacers (50da, 50fa) therebetween. The frame spacers (50fa) are provided on at least the first substrate (60a), and the pixel spacers (50da) are provided on the second substrate (80a).

Description

display device

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

[0002] In recent years, organic electroluminescence (EL) display devices using organic electroluminescence (EL) elements (light-emitting elements) have been attracting attention as self-luminous display devices to replace liquid crystal display devices. Development of quantum-dot light-emitting diode (QLED) display devices equipped with quantum-dot light-emitting diode (QLED) light-emitting elements using a quantum dot-containing layer is also underway. Self-luminous display devices are provided with a plurality of thin film transistors (TFTs) and a plurality of light-emitting elements corresponding to subpixels that form a display area for displaying images. Furthermore, in self-luminous display devices, a sealing structure has been proposed in which a substrate (backplane substrate) on which the light-emitting elements are provided is sealed with an opposing substrate facing the substrate in order to prevent deterioration of the light-emitting elements due to the intrusion of moisture, oxygen, and the like.

[0003] For example, Patent Document 1 proposes a display device including a first substrate, a second substrate, and a plurality of columnar spacers arranged between the first substrate and the second substrate.

[0004] JP 2009-237578 A

[0005] Incidentally, when the above-described sealing structure is adopted in an organic EL display device or a QLED display device, a plurality of spacers are generally provided on a backplane substrate (first substrate in Patent Document 1), as described in Patent Document 1. The plurality of spacers are arranged between subpixels at a higher density than the plurality of light-emitting elements, and therefore, the spacers may reduce the luminance of emitted light.

[0006] The present invention has been made in consideration of the above points, and its purpose is to suppress the decrease in luminance caused by spacers in a display device having a sealing structure in which two opposing substrates are sealed via a plurality of spacers.

[0007] In order to achieve the above-mentioned object, the display device of the present invention comprises a first substrate having a display area and a frame area provided around the display area, and having a plurality of light-emitting elements provided corresponding to a plurality of sub-pixels constituting the display area, a second substrate arranged opposite the first substrate, and a plurality of pixel spacers arranged in the display area and a plurality of frame spacers arranged in the frame area, which are interposed between the first substrate and the second substrate, and the plurality of light-emitting elements of the first substrate are sealed by the second substrate via the plurality of pixel spacers and the plurality of frame spacers, and is characterized in that the plurality of frame spacers are provided on at least the first substrate, and the plurality of pixel spacers are provided on the second substrate.

[0008] According to the present invention, in a display device having a sealing structure in which two opposing substrates are sealed via a plurality of spacers, it is possible to suppress a decrease in luminance caused by the spacers.

[0009] FIG. 1 is a plan view showing a schematic configuration of an organic EL display device according to a first embodiment of the present invention. FIG. 2 is a plan view of a display region of the organic EL display device according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of the organic EL display device according to the first embodiment of the present invention taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view showing a manufacturing process of the organic EL display device according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view showing a first substrate constituting the organic EL display device according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view showing a second substrate constituting the organic EL display device according to the first embodiment of the present invention. FIG. 7 is an equivalent circuit diagram of a TFT layer constituting the organic EL display device according to the first embodiment of the present invention. FIG. 8 is a cross-sectional view of an organic EL layer constituting the organic EL display device according to the first embodiment of the present invention. FIG. 9 is a cross-sectional view showing a manufacturing process of an organic EL display device according to a second embodiment of the present invention, corresponding to FIG. 4. FIG. 10 is a cross-sectional view showing a first substrate constituting the organic EL display device according to the second embodiment of the present invention, corresponding to FIG. 5. FIG. 11 is a cross-sectional view showing a second substrate constituting the organic EL display device according to the second embodiment of the present invention, corresponding to FIG. 6.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0011] First Embodiment FIGS. 1 to 8 show a first embodiment of a display device according to the present invention. In the following embodiments, an organic EL display device including organic EL elements will be exemplified as a display device including light-emitting elements. FIG. 1 is a plan view showing a schematic configuration of an organic EL display device 90a according to this embodiment. FIG. 2 is a plan view of a display region D of the organic EL display device 90a. FIG. 3 is a cross-sectional view of the organic EL display device 90a taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view showing a manufacturing process of the organic EL display device 90a. FIG. 5 is a cross-sectional view showing a first substrate 60a constituting the organic EL display device 90a. FIG. 6 is a cross-sectional view showing a second substrate 80a constituting the organic EL display device 90a. FIG. 7 is an equivalent circuit diagram of a TFT layer 30 (thin film transistor layer) constituting the organic EL display device 90a. FIG. 8 is a cross-sectional view of an organic EL layer 33 constituting the organic EL display device 90a.

[0012] <Organic EL Display Device> As shown in FIG. 1 , the organic EL display device 90a includes, for example, a rectangular display area D for displaying images and a frame area F surrounding the display area D. While the rectangular display area D is illustrated in this embodiment, the rectangular shape also includes other shapes, such as shapes with arc-shaped sides, arc-shaped corners, or shapes with notches along the sides. The organic EL display device 90a defines a direction X parallel to the substrate surface of the resin substrate 10 (described later), a direction Y perpendicular to the direction X and parallel to the substrate surface, and a direction Z perpendicular to the directions X and Y (see FIGS. 3 to 6 ). The arrow of the direction Z indicates that the second substrate 80a is positioned above the first substrate 60a in the organic EL display device 90a.

[0013] In the display region D, a plurality of sub-pixels P are arranged in a matrix, as shown in Fig. 2. In the display region D, for example, a sub-pixel P having a red light-emitting region Lr for displaying red, a sub-pixel P having a green light-emitting region Lg for displaying green, and a sub-pixel P having a blue light-emitting region Lb for displaying blue are arranged adjacent to one another, as shown in Fig. 2. In the display region D, one pixel is formed by, for example, three adjacent sub-pixels P each having a red light-emitting region Lr, a green light-emitting region Lg, and a blue light-emitting region Lb. The arrangement of the sub-pixels P is not particularly limited, and examples thereof include a pentatile arrangement and a stripe arrangement.

[0014] A terminal portion T is provided to extend in one direction (direction Y, the vertical direction in FIG. 1 ) at one end (the right end in FIG. 1 ) of the frame region F. A folding portion (not shown) that can be folded, for example, 180° (in a U-shape) with direction Y as the folding axis may be provided in the frame region F between the display region D and the terminal portion T to extend in one direction (direction Y).

[0015] As shown in FIG. 3, the organic EL display device 90a includes a first substrate 60a, a second substrate 80a, and a plurality of pixel spacers 50da and a plurality of frame spacers 50fa interposed between the first substrate 60a and the second substrate 80a.

[0016] The first substrate 60a is a backplane substrate including a plurality of organic EL elements 35 (light-emitting elements) (described later) that constitute the display region D. The second substrate 80a is an opposing substrate disposed opposite the first substrate 60a. The pixel spacers 50da are photospacers disposed in the display region D. The pixel spacers 50da are provided between a plurality of sub-pixels P that constitute the display region D. The frame spacers 50fa are photospacers disposed in the frame region F.

[0017] As shown in FIG. 3 , the pixel spacers 50da and the frame spacers 50fa are columnar objects that maintain the distance between the first substrate 60a and the second substrate 80a. The pixel spacers 50da and the frame spacers 50fa have approximately the same thickness (dimension in the Z direction). The pixel spacers 50da and the frame spacers 50fa are arranged, for example, in an island-like pattern at equal intervals. The pixel spacers 50da and the frame spacers 50fa may have the same or different density (arrangement spacing), thickness, shape, size (area, volume), etc. In other words, the spacer density, thickness, shape, size, etc. may be different between the display region D and the frame region F. For example, the density of the pixel spacers 50da arranged at high density corresponding to the subpixels P may be set higher than the density of the frame spacers 50fa.

[0018] The pixel spacer 50da and the frame spacer 50fa are made of an organic resin film, which is a single layer or a multilayer film made of an organic material such as an acrylic resin, a polyurea resin, a parylene resin, a polyimide resin, or a polyamide resin. The pixel spacer 50da and the frame spacer 50fa are made of an organic material such as silicon oxide (SiO ２ ) and aluminum oxide (Al ２ O ３ ), trisilicon tetranitride (Si ３ N ４ The pixel spacer 50da may be formed of a single layer or a laminated inorganic film made of an inorganic material such as silicon nitride (SiNx (x is a positive number)) or silicon carbonitride (SiCN). The pixel spacer 50da and the frame spacer 50fa may be formed of the same material, or may be formed of different materials. The pixel spacer 50da may be formed of the same material as organic resin films such as the edge cover 32 described below and the first planarization film 20 and second planarization film 22. The pixel spacer 50da may be formed of a laminated film made of organic resin films such as the first planarization film 20, the second planarization film 22, and the edge cover 32.

[0019] 3, the organic EL elements 35 constituting the first substrate 60a are sealed by the second substrate 80a via the pixel spacers 50da and the frame spacers 50fa. In this way, the organic EL display device 90a has a sealing structure in which the two opposing first and second substrates 60a and 80a are sealed via the pixel spacers 50da and the frame spacers 50fa.

[0020] The sealing structure between the first substrate 60a and the second substrate 80a is not particularly limited, and examples thereof include a structure in which the first substrate 60a and the second substrate 80a are bonded via a dam material 51 and a fill material 52 (sealing material), as shown in FIG. 3 . The dam material 51 is disposed between the first substrate 60a and the second substrate 80a at the outer periphery of the frame region F so as to surround the display region D. The fill material 52 fills the gap between the first substrate 60a and the second substrate 80a, which is surrounded by the dam material 51. The dam material 51 and the fill material 52 bond the first substrate 60a and the second substrate 80a, sealing the multiple organic EL elements 35. The dam material 51 and the fill material 52 are made of an organic resin material, such as an epoxy resin, an acrylic resin, a silicone resin, or a fluororesin.

[0021] In conventional display devices having the above-described sealing structure, a plurality of spacers are typically provided on a backplane substrate. That is, both the plurality of spacers arranged in the display region and the plurality of spacers arranged in the frame region are provided on the same backplane substrate. The plurality of spacers arranged in the display region are arranged between subpixels at a higher density than the plurality of light-emitting elements. The light-emitting element layer formed on the plurality of spacers arranged at a high density in the display region is formed in an uneven shape due to the influence of the unevenness caused by the spacers. Therefore, in conventional display devices, the light-emitting brightness is reduced due to the spacers arranged in the display region.

[0022] In contrast, in the organic EL display device 90a, as shown in FIG. 4, the first substrate 60a, which is a backplane substrate, does not have the plurality of pixel spacers 50da densely arranged in the display region D. Specifically, as shown in FIG. 4, the plurality of frame spacers 50fa arranged in the frame region F are provided on the first substrate 60a. On the other hand, the plurality of pixel spacers 50da arranged in the display region D are provided on the second substrate 80a, not the first substrate 60a. As shown in FIGS. 4 and 5, the arrangement region of the spacers on the first substrate 60a is specified as the frame region F. As shown in FIGS. 4 and 6, the arrangement region of the spacers on the second substrate 80a is specified as the display region D. In the organic EL display device 90a, the plurality of pixel spacers 50da arranged in the display region D and the plurality of frame spacers 50fa arranged in the frame region F are formed on separate substrates.

[0023] In the organic EL display device 90a having the above-described sealing structure, as shown in FIGS. 4 and 5 , the first substrate 60a, which is a backplane substrate, does not have the pixel spacers 50da, which serve as structural components, formed thereon in the display region D. In other words, the pixel spacers 50da are not present below the organic EL element layer 40. Because the organic EL element layer 40 is not formed on the pixel spacers 50da, it is not affected by the unevenness caused by the pixel spacers 50da. Therefore, in the organic EL display device 90a, a decrease in luminance due to the pixel spacers 50da arranged in the display region D is suppressed.

[0024] In the organic EL display device 90a having the above-described sealing structure, the bonding accuracy between the first substrate 60a and the second substrate 80a is relatively low, so alignment spacers, for example, may be provided. In this case, it is difficult to arrange the alignment spacers at desired positions on the second substrate 80a. On the other hand, the multiple frame spacers 50fa provided on the first substrate 60a can achieve high alignment accuracy, so by using the multiple frame spacers 50fa (one or more of which are alignment spacers), it is easy to arrange the alignment spacers at desired positions on the first substrate 60a.

[0025] Furthermore, in the organic EL display device 90a having the above-described sealing structure, the first substrate 60a has more layers that can form the spacer than the second substrate 80a, and therefore, by making the spacer a laminated film, for example, the thickness of the frame spacer 50fa can be formed relatively freely.

[0026] <First Substrate> As shown in FIG. 5 , the first substrate 60a (backplane substrate) has a resin substrate 10 provided as a base substrate, a TFT layer 30 provided on the resin substrate 10, an organic EL element layer 40 provided as a light-emitting element layer that constitutes the display area D, and a plurality of frame spacers 50fa provided on the organic EL element layer 40.

[0027] The resin substrate 10 is made of an organic resin material such as polyimide resin.

[0028] As shown in FIG. 5, the TFT layer 30 includes a base coat film 11 provided on a resin substrate 10, a plurality of first TFTs 9 a, a plurality of second TFTs 9 b, a plurality of third TFTs 9 c, and a plurality of capacitors 9 d provided on the base coat film 11 for each sub-pixel P, and a first inorganic insulating film 19, a first planarization film 20, and a second planarization film 22 provided on each of the first TFTs 9 a, the second TFTs 9 b, the third TFTs 9 c, and the capacitors 9 d.

[0029] 5, in the TFT layer 30, a base coat film 11, a semiconductor film that will become the semiconductor layers 12a, 12b, etc., a gate insulating film 13, a first metal film that will become the gate electrodes 14a, 14b, the lower conductive layer 14c, the gate line 14g (see FIGS. 2 and 7), the light-emitting control line 14e (see FIGS. 2 and 7), etc., a first interlayer insulating film 15, a second metal film that will become the upper conductive layer 16c, etc., a second interlayer insulating film 17, a third metal film that will become the source line 18f (see FIGS. 2 and 7), the power supply line 18g (see FIGS. 2 and 7), the source electrodes 18a, 18c, the drain electrodes 18b, 18d, etc., a first inorganic insulating film 19, a first planarization film 20, a fourth metal film that will become the relay electrode 21, etc., and a second planarization film 22 are laminated in this order on a resin substrate 10.

[0030] The base coat film 11, the gate insulating film 13, the first interlayer insulating film 15, the second interlayer insulating film 17, and the first inorganic insulating film 19 may be made of, for example, silicon nitride (SiNx (x is a positive number)), silicon oxide (SiO ２ The semiconductor layers 12a and 12b are each composed of a single layer or a stacked layer of an inorganic insulating film such as silicon oxynitride (SiON). The semiconductor layers 12a and 12b are composed of, for example, a low-temperature polysilicon film or an In—Ga—Zn—O-based oxide semiconductor film. The first metal film, the second metal film, the third metal film, and the fourth metal film are each composed of, for example, a metal single layer film of molybdenum (Mo), titanium (Ti), aluminum (Al), copper (Cu), tungsten (W), or the like, or a metal stacked layer film of Mo (upper layer) / Al (middle layer) / Mo (lower layer), Ti / Al / Ti, Al (upper layer) / Ti (lower layer), Cu / Mo, Cu / Ti, or the like.

[0031] As shown in FIG. 2 , the TFT layer 30 is provided with a plurality of gate lines 14g extending parallel to one another in the X direction in the figure. The TFT layer 30 is also provided with a plurality of light-emitting control lines 14e extending parallel to one another in the X direction in the figure. Each light-emitting control line 14e is provided adjacent to a corresponding gate line 14g. The TFT layer 30 is also provided with a plurality of source lines 18f extending parallel to one another in the Y direction in the figure. The TFT layer 30 is also provided with a plurality of power supply lines 18g extending parallel to one another in the Y direction in the figure. Each power supply line 18g is provided adjacent to a corresponding source line 18f. As shown in FIG. 7 , the TFT layer 30 includes a first TFT 9a, a second TFT 9b, a third TFT 9c, and a capacitor 9d in each sub-pixel P. The first TFT 9a, the second TFT 9b, and the third TFT 9c are p-type TFTs in which the semiconductor layers 12a, 12b, etc. are doped with impurities such as boron.

[0032] As shown in FIG. 7 , the first TFT 9a is electrically connected to the corresponding gate line 14g, source line 18f, and second TFT 9b in each subpixel P. As shown in FIG. 5 , the first TFT 9a includes 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 on a second interlayer insulating film 17. The semiconductor layers 12a and 12b are semiconductor films made of, for example, an In—Ga—Zn—O-based oxide semiconductor, and are provided in island shapes on the base coat film 11 as shown in FIG. 5 . The semiconductor layers 12a and 12b include source and drain regions defined spaced apart from each other and a channel region defined between the source and drain regions. The gate electrode 14a is provided so as to overlap the channel region of the semiconductor layer 12a and is configured to control conduction between the source electrode 18a and the drain electrode 18b. As shown in FIG. 5, the source electrode 18a and the drain electrode 18b are electrically connected to the source region and the drain region of the semiconductor layer 12a, respectively, through contact holes formed in the stacked film of the gate insulating film 13, the first interlayer insulating film 15, and the second interlayer insulating film 17.

[0033] 7, the second TFT 9b is electrically connected to the corresponding first TFT 9a, power supply line 18g, and third TFT 9c in each subpixel P. The second TFT 9b has substantially the same structure as the first TFT 9a and the third TFT 9c.

[0034] As shown in FIG. 7 , in each subpixel P, the third TFT 9c is electrically connected to the corresponding second TFT 9b, a first electrode 31 of an organic EL element 35 (described later), and an emission control line 14e. As shown in FIG. 5 , the third TFT 9c includes 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. The gate electrode 14b is arranged to overlap a channel region of the semiconductor layer 12b and is configured to control conduction between the source electrode 18c and the drain electrode 18d. As shown in FIG. 5 , the source electrode 18c and the drain electrode 18d are electrically connected to the source region and the drain region of the semiconductor layer 12b, respectively, via contact holes formed in the stacked film of the gate insulating film 13, the first interlayer insulating film 15, and the second interlayer insulating film 17.

[0035] In this embodiment, the first TFT 9a, the second TFT 9b, and the third TFT 9c are illustrated as being of a top gate type, but the first TFT 9a, the second TFT 9b, and the third TFT 9c may be of a bottom gate type.

[0036] 7, the capacitor 9d is electrically connected to the corresponding first TFT 9a and power supply line 18g in each subpixel P. Here, as shown in FIG. 5, the capacitor 9d includes a lower conductive layer 14c formed of a first metal film, a first interlayer insulating film 15 provided so as to cover the lower conductive layer 14c, and an upper conductive layer 16c formed of a second metal film on the first interlayer insulating film 15 so as to overlap the lower conductive layer 14c. The upper conductive layer 16c is electrically connected to the power supply line 18g via a contact hole (not shown) formed in the second interlayer insulating film 17.

[0037] The first planarization film 20 and the second planarization film 22 have flat surfaces in the display region D and are made of, for example, an organic resin material such as polyimide resin or acrylic resin, or a polysiloxane-based SOG (spin on glass) material.

[0038] 5, a relay electrode 21 formed of the same material as the fourth metal film is provided between the first planarization film 20 and the second planarization film 22. The relay electrode 21 is electrically connected to the drain electrode 18d of the third TFT 9c through a first contact hole Ha formed in the laminated film of the first inorganic insulating film 19 and the first planarization film 20.

[0039] As shown in FIG. 5, the organic EL element layer 40 includes a plurality of organic EL elements 35 as a plurality of light-emitting elements arranged in a matrix corresponding to a plurality of sub-pixels P.

[0040] As shown in Figure 5, the organic EL element 35 includes a plurality of first electrodes 31 arranged in order on the second planarization film 22, a plurality of organic EL layers 33 (light-emitting functional layers) arranged on the first electrodes 31 in each sub-pixel P, and a second electrode 34 arranged on the organic EL layer 33 in common to the plurality of sub-pixels P.

[0041] As shown in FIG. 5 , the first electrodes 31 are provided in a matrix on the second planarization film 22 so as to correspond to the plurality of subpixels P. As shown in FIG. 5 , the first electrodes 31 are electrically connected to the relay electrodes 21 of each subpixel via contact holes Hb formed in the second planarization film 22. The first electrodes 31 are electrically connected to the drain electrodes 18 d (or source electrodes 18 c) of each third TFT 9 c via the relay electrodes 21. The first electrodes 31 also have the function of injecting holes (positive holes) into the organic EL layer 33. The first electrodes 31 are preferably formed of a material with a large work function to improve the efficiency of hole injection into the organic EL layer 33. Here, examples of materials constituting the first electrode 31 include metal materials such as silver (Ag), aluminum (Al), vanadium (V), cobalt (Co), nickel (Ni), tungsten (W), gold (Au), titanium (Ti), ruthenium (Ru), manganese (Mn), indium (In), ytterbium (Yb), lithium fluoride (LiF), platinum (Pt), palladium (Pd), molybdenum (Mo), iridium (Ir), and tin (Sn). Examples of materials constituting the first electrode 31 include astatine (At) / astatine oxide (AtO２ The first electrode 31 may be made of an alloy of tin oxide (SnO), zinc oxide (ZnO), indium tin oxide (ITO), indium zinc oxide (IZO), or another conductive oxide. The first electrode 31 may be formed by stacking multiple layers made of the above materials. Examples of compound materials with a large work function include indium tin oxide (ITO) and indium zinc oxide (IZO).

[0042] The peripheral edge of the first electrode 31 is covered with an edge cover 32 provided in a lattice pattern and shared by multiple sub-pixels P. Here, examples of materials constituting the edge cover 32 include positive photosensitive resin materials such as polyimide resin, acrylic resin, polysiloxane resin, and novolac resin, and polysiloxane-based SOG materials.

[0043] 5, the organic EL layer 33 is disposed on each first electrode 31, and is provided in a matrix so as to correspond to a plurality of sub-pixels P. Here, each organic EL layer 33 includes a hole injection layer 1, a hole transport layer 2, a light-emitting layer 3, an electron transport layer 4, and an electron injection layer 5, which are provided in this order on the first electrode 31, as shown in FIG.

[0044] The hole injection layer 1 is also called an anode buffer layer, and has the function of bringing the energy levels of the first electrode 31 and the organic EL layer 33 closer to each other, thereby improving the efficiency of hole injection from the first electrode 31 to the organic EL layer 33. Examples of materials constituting the hole injection layer 1 include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, phenylenediamine derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, and stilbene derivatives.

[0045] The hole transport layer 2 has a function of improving the efficiency of transporting holes from the first electrode 31 to the organic EL layer 33. Examples of materials constituting the hole transport layer 2 include 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.

[0046] The light-emitting layer 3 is a region into which holes and electrons are injected from the first electrode 31 and the second electrode 34, respectively, and where the holes and electrons recombine when a voltage is applied between the first electrode 31 and the second electrode 34. The light-emitting layer 3 is made of a material with high luminous efficiency. Examples of materials that can be used for the light-emitting layer 3 include metal oxinoid compounds (8-hydroxyquinoline metal complexes), naphthalene derivatives, anthracene derivatives, diphenylethylene derivatives, vinylacetone derivatives, triphenylamine derivatives, butadiene derivatives, coumarin derivatives, benzoxazole derivatives, oxadiazole derivatives, oxazole derivatives, benzimidazole derivatives, thiadiazole derivatives, benzthiazole derivatives, styryl derivatives, styrylamine derivatives, bisstyrylbenzene derivatives, trisstyrylbenzene derivatives, perylene derivatives, perinone derivatives, aminopyrene derivatives, pyridine derivatives, rhodamine derivatives, aquidin derivatives, phenoxazone, quinacridone derivatives, rubrene, poly-p-phenylenevinylene, and polysilane.

[0047] The electron transport layer 4 has a function of efficiently transferring electrons to the light-emitting layer 3. Examples of materials constituting the electron transport layer 4 include organic compounds such as oxadiazole derivatives, triazole derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, tetracyanoanthraquinodimethane derivatives, diphenoquinone derivatives, fluorenone derivatives, silole derivatives, and metal oxinoid compounds.

[0048] The electron injection layer 5 has a function of bringing the energy levels of the second electrode 34 and the organic EL layer 33 closer to each other and improving the efficiency of electron injection from the second electrode 34 to the organic EL layer 33, and this function can reduce the driving voltage of the organic EL element 35. The electron injection layer 5 is also called a cathode buffer layer. Here, examples of materials constituting the electron injection layer 5 include lithium fluoride (LiF), magnesium fluoride (MgF ２ ), calcium fluoride (CaF ２ ), strontium fluoride (SrF ２ ), barium fluoride (BaF ２ inorganic alkali compounds such as aluminum oxide (Al ２ O ３ ), strontium oxide (SrO), etc.

[0049] 5 , the second electrode 34 is provided to cover each organic EL layer 33 and the edge cover 32. The second electrode 34 has a function of injecting electrons into the organic EL layer 33. The second electrode 34 is preferably made of a material with a small work function to improve the efficiency of electron injection into the organic EL layer 33. Examples of materials that can be used for the second electrode 34 include silver (Ag), aluminum (Al), vanadium (V), cobalt (Co), nickel (Ni), tungsten (W), gold (Au), calcium (Ca), titanium (Ti), yttrium (Y), sodium (Na), ruthenium (Ru), manganese (Mn), indium (In), magnesium (Mg), lithium (Li), ytterbium (Yb), and lithium fluoride (LiF). The second electrode 34 may be made of, for example, magnesium (Mg) / copper (Cu), magnesium (Mg) / silver (Ag), sodium (Na) / potassium (K), or astatine (At) / astatine oxide (AtO ２ The second electrode 34 may be formed of an alloy such as lithium (Li) / aluminum (Al), lithium (Li) / calcium (Ca) / aluminum (Al), or lithium fluoride (LiF) / calcium (Ca) / aluminum (Al). The second electrode 34 may be formed of a conductive oxide such as tin oxide (SnO), zinc oxide (ZnO), indium tin oxide (ITO), or indium zinc oxide (IZO). The second electrode 34 may be formed by stacking multiple layers made of the above materials. Examples of materials with a low work function include magnesium (Mg), lithium (Li), lithium fluoride (LiF), magnesium (Mg) / copper (Cu), magnesium (Mg) / silver (Ag), sodium (Na) / potassium (K), lithium (Li) / aluminum (Al), lithium (Li) / calcium (Ca) / aluminum (Al), and lithium fluoride (LiF) / calcium (Ca) / aluminum (Al).

[0050] 5 , the frame spacer 50fa is provided on the organic EL element layer 40 in the frame region F. Specifically, the frame spacer 50fa is provided on the second electrode 34 that constitutes the organic EL element layer 40 in the frame region F. As described above, the frame spacer 50fa is not provided in the display region D.

[0051] In the first substrate 60a described above, in each sub-pixel P, when a gate signal is input to the first TFT 9a via the gate line 14g, the first TFT 9a is turned on, a predetermined voltage corresponding to the source signal is written to the gate electrode of the second TFT 9b and the capacitor 9d via the source line 18f, and when a light-emission control signal is input to the third TFT 9c via the light-emission control line 14e, the third TFT 9c is turned on, and a current corresponding to the gate voltage of the second TFT 9b is supplied from the power supply line 18g to the organic EL layer 33, causing the light-emitting layer 3 of the organic EL layer 33 to emit light, thereby displaying an image. Note that, in the first substrate 60a, even if the first TFT 9a is turned off, the gate voltage of the second TFT 9b is held by the capacitor 9d, so that light emission by the light-emitting layer 3 is maintained in each sub-pixel P until a gate signal for the next frame is input.

[0052] <Second Substrate> As shown in FIG. 6 , the second substrate 80a (opposing substrate) has a glass substrate 70 provided as a base substrate, an inorganic laminate film 75 provided on the glass substrate 70, and a plurality of pixel spacers 50da provided on the inorganic laminate film 75.

[0053] The glass substrate 70 is a plate that forms the base of the second substrate 80a. That is, the second substrate 80a is a substrate that glass-seals the first substrate 60a.

[0054] In the conventional display device having the above-mentioned sealing structure, an inorganic film formed on the glass substrate of the opposing substrate is generally made of silicon tetranitride (Si ３ N ４A silicon nitride (SiNx (x is a positive number)) film such as SiNx is formed on the entire surface of the substrate. By forming the SiNx film, the opposing substrate becomes colored. Therefore, in conventional display devices, the emission brightness decreases due to the coloration of the opposing substrate.

[0055] In contrast, in the organic EL display device 90a, the inorganic laminated film 75 provided on the glass substrate 70 of the second substrate 80a is a silicon nitride (SiNx (x is a positive number)) film and a silicon oxide (SiO ２ ) film. ２ The film reduces coloring of the second substrate 80a caused by the SiNx film and improves transmittance, thereby suppressing a decrease in luminance of emitted light caused by coloring of the second substrate 80a in the organic EL display device 90a.

[0056] The inorganic laminated film 75 is a SiNx film, a SiO ２ Film and SiO ２ A laminated film (SiO ２ Film / SiO ２ As shown in FIG. 6, the inorganic laminated film 75 is preferably configured as a laminated structure in which, for example, a first inorganic film 71 and a second inorganic film 72 are laminated in this order. The thickness of each layer is not particularly limited and may be determined appropriately, for example, about 50 nm. As a specific example, the first inorganic film 71 is configured as a SiNx film and a SiO ２ A laminated film (SiO ２ The second inorganic film 72 is formed in a thickness of 50 nm (SiO film / SiNx film=50 nm / 50 nm). ２ The SiNx film and SiO ２ The thickness of each film is not limited to the above, and may be set to an optimum value by, for example, optical simulation.

[0057] The inorganic laminated film 75 may be made of, for example, aluminum oxide (Al ２ O ３ ), or a film made of an inorganic material such as silicon carbonitride (SiCN).

[0058] Furthermore, a metal layer (not shown) for forming an alignment mark (not shown) may be interposed between the inorganic stacked films 75 (for example, between the first inorganic film 71 and the second inorganic film 72).

[0059] 6 , the pixel spacer 50da is provided on the inorganic stacked film 75 in the display region D. Specifically, the pixel spacer 50da is provided on the second inorganic film 72 that constitutes the inorganic stacked film 75 in the display region D. As described above, the pixel spacer 50da is not provided in the frame region F.

[0060] <Method for Manufacturing Organic EL Display Device> Next, a method for manufacturing the organic EL display device 90a of this embodiment will be described. The method for manufacturing the organic EL display device 90a includes a first substrate forming step, a second substrate forming step, and a sealing step.

[0061] [First Substrate Forming Step] The first substrate forming step includes a TFT layer forming step, an organic EL element layer forming step, and a first spacer forming step.

[0062] (TFT layer formation process) For example, a base coat film 11, a first TFT 9 a, a second TFT 9 b, a third TFT 9 c, a capacitor 9 d, a first inorganic insulating film 19, a first planarization film 20, a second planarization film 22, etc. are formed in this order on the surface of a resin substrate 10 formed on a glass substrate using a well-known method, thereby forming a TFT layer 30.

[0063] (Organic EL element layer formation process) In the display region D, a first electrode 31, an edge cover 32, an organic EL layer 33 (hole injection layer 1, hole transport layer 2, light-emitting layer 3, electron transport layer 4, electron injection layer 5) and a second electrode 34 are formed using a well-known method on the second planarization film 22 of the TFT layer 30 formed in the TFT layer formation process, thereby forming an organic EL element 35 and forming an organic EL element layer 40.

[0064] (First Spacer Formation Process) In the frame region F, a film of an organic resin material is formed using a well-known method on the second electrode 34 of the organic EL element layer 40 formed in the organic EL element layer formation process, and then the organic resin film is patterned to form a plurality of frame spacers 50fa. For example, when forming the edge cover 32, the frame spacers 50fa may be formed using the same material as the edge cover 32. Alternatively, the frame spacers 50fa may be formed as a laminated film using the edge cover 32 and the layers of the first planarization film 20 and second planarization film 22.

[0065] Finally, a protective sheet (not shown) is attached to the surface of the substrate, and then laser light is irradiated from the glass substrate side of the resin substrate 10 to peel the glass substrate from the underside of the resin substrate 10, and a protective sheet (not shown) is attached to the underside of the resin substrate 10 from which the glass substrate has been peeled. Through the above steps, the first substrate 60a can be manufactured.

[0066] [Second Substrate Forming Step] The second substrate forming step includes an inorganic laminate film forming step and a second spacer forming step.

[0067] (Inorganic Laminated Film Formation Process) For example, a SiNx film and a SiO 3 film are formed on the surface of a glass substrate 70 as a base substrate in this order from the bottom by using a known method. ２ A laminated film (SiO ２ a first inorganic film 71 (SiO film / SiNx film=50 nm / 50 nm) and a ２ A second inorganic film 72 of a single layer film (50 nm) is formed in this order to form an inorganic laminated film 75 .

[0068] (Second Spacer Forming Process) In the display region D, an organic resin material is deposited by a known method on the second inorganic film 72 of the inorganic laminate film 75 formed in the inorganic laminate film forming process, and then the organic resin film is patterned to form a plurality of pixel spacers 50da. Through the above processes, the second substrate 80a can be manufactured.

[0069] [Sealing Process] For example, a dam material 51 and a filler material 52 are applied to one of the first substrate 60a and the second substrate 80a using a well-known method. Next, the first substrate 60a and the second substrate 80a are bonded together via a plurality of pixel spacers 50da, a plurality of frame spacers 50fa, the dam material 51, and the filler material 52. The distance between the first substrate 60a and the second substrate 80a is maintained by the plurality of frame spacers 50fa and the plurality of pixel spacers 50da. Finally, the dam material 51 and the filler material 52 are cured to seal the first substrate 60a and the second substrate 80a.

[0070] In this manner, the organic EL display device 90a can be manufactured.

[0071] <Effects> As described above, the organic EL display device 90a of this embodiment can achieve the following effects. (1) The organic EL display device 90a has a sealing structure that seals two opposing substrates, the first substrate 60a (backplane substrate) and the second substrate 80a (counter substrate), via a plurality of pixel spacers 50da and a plurality of frame spacers 50fa. The frame spacers 50fa are provided on the first substrate 60a, while the pixel spacers 50da are provided on the second substrate 80a. In the display region D, the pixel spacers 50da are not formed on the first substrate 60a, so the organic EL element layer 40 is not affected by unevenness caused by the pixel spacers 50da. Therefore, the organic EL display device 90a can suppress a decrease in luminance due to the pixel spacers 50da arranged in the display region D. (2) In the organic EL display device 90a, the inorganic laminated film 75 constituting the second substrate 80a is formed of a SiNx film and a SiO ２ and optimizing the thickness of each film (e.g., SiO ２ Film / SiO ２(3) In the organic EL display device 90a, the film configuration of the substrate on which the pixel spacers 50da are formed and the film configuration of the second substrate 80a are optimized by the above (1) and (2), and the optical transmittance is improved, resulting in an improvement in the quality of the display device.

[0072] Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. 9 to 11. FIG. 9 is a cross-sectional view showing a manufacturing process of an organic EL display device 90b according to this embodiment, and corresponds to FIG. 4. FIG. 10 is a cross-sectional view showing a first substrate 60b constituting the organic EL display device 90b, and corresponds to FIG. 5. FIG. 11 is a cross-sectional view showing a second substrate 80b constituting the organic EL display device 90b, and corresponds to FIG. 6. The overall configuration of the organic EL display device 90b is the same as that of the first embodiment described above, except for the configuration of the multiple first frame spacers 50fba, 50fbb arranged in the frame region F, and therefore a detailed description thereof will be omitted here. Furthermore, components similar to those of the first embodiment described above will be assigned the same reference numerals and their description will be omitted.

[0073] The organic EL display device 90b differs from the organic EL display device 90a in that the frame spacers arranged in the frame region F are provided on both the first substrate 60b and the second substrate 80b. As shown in Fig. 9, the frame spacers in the organic EL display device 90b include a plurality of first frame spacers 50fba provided on the first substrate 60b and a plurality of second frame spacers 50fbb provided on the second substrate 80b. The first frame spacers 50fba and the second frame spacers 50fbb are arranged opposite each other.

[0074] 9 and 10, the first substrate 60b (backplane substrate) has a plurality of first frame spacers 50fba provided on the organic EL element layer 40. The plurality of first frame spacers 50fba are provided on the second electrodes 34 of the organic EL element layer 40 in the frame region F. Similar to the first substrate 60a, the first substrate 60b, which is a backplane substrate, does not have a plurality of pixel spacers 50da, which serve as structures, formed in the display region D. The frame spacers 50fba are thinner than the frame spacers 50fa of the first substrate 60a.

[0075] 9 and 11 , the second substrate 80b (opposing substrate) has a plurality of pixel spacers 50da and a plurality of second frame spacers 50fbb provided on the inorganic laminate film 75. Similar to the second substrate 80a, the plurality of pixel spacers 50da are provided on the second inorganic film 72 of the inorganic laminate film 75 in the display region D. The plurality of second frame spacers 50fbb are provided on the second inorganic film 72 of the inorganic laminate film 75 in the frame region F. That is, the second substrate 80b has two types of spacers, including the pixel spacers 50da in the display region D and the second frame spacers 50fbb in the frame region F. In the frame region F, the second substrate 80a is not provided with any spacers, whereas the second substrate 80b is provided with a plurality of second frame spacers 50fbb.

[0076] 10 and 11 , the thickness T1 of the first frame spacer 50fba and the thickness T2 of the second frame spacer 50fbb are smaller than the thickness T3 of the pixel spacer 50da. For example, the sum of the thickness T1 of the first frame spacer 50fba and the thickness T2 of the second frame spacer 50fbb is approximately the same as the thickness T3 of the pixel spacer 50da (T1 + T2 ≈ T3). Note that the thickness T1 of the first frame spacer 50fba and the thickness T2 of the second frame spacer 50fbb may be the same (half the thickness T3 of the pixel spacer 50da) or may be different.

[0077] The organic EL display device 90b can be fabricated by modifying the first substrate forming step and the second substrate forming step of the organic EL display device 90a as follows.

[0078] [First Substrate Forming Process (First Spacer Forming Process)] In the first spacer forming process of the first substrate forming process, for example, by half exposure using a half-tone mask, a plurality of first frame spacers 50fba are formed, each having a thickness T1 that is smaller than the thickness of the frame spacers 50fa of the first substrate 60a or the thickness T3 of the pixel spacers 50da of the second substrate 80b. This forms the first substrate 60b having a plurality of first frame spacers 50fba.

[0079] [Second Substrate Forming Process (Second Spacer Forming Process)] In the second spacer forming process of the second substrate forming process, when forming pixel spacers 50da in the display region D, a plurality of second frame spacers 50fbb having a thickness T2 that is smaller than the thickness T3 of the pixel spacers 50da or approximately the same as the thickness T1 of the first frame spacers 50fba are formed on the second inorganic film 72 of the inorganic stacked film 75 in the frame region F by, for example, half-exposure using a half-tone mask. This forms a second substrate 80b having a plurality of pixel spacers 50da and a plurality of second frame spacers 50fbb.

[0080] <Effects> The organic EL display device 90b described above has the following effect in addition to the effects of the organic EL display device 90a. (4) In the organic EL display device 90b, a plurality of first frame spacers 50fba having a thickness T1 are provided on the first substrate 60b as frame spacers arranged in the frame region F. Furthermore, a plurality of second frame spacers 50fbb having a thickness T2 are provided on the second substrate 80b, each facing the first frame spacers 50fba. This facilitates fine adjustment of the thickness T1 of the first frame spacers 50fba and the thickness T2 of the second frame spacers 50fbb arranged in the frame region F, and the thickness T3 of the pixel spacers 50da arranged in the display region D (T1 + T2 ≈ T3). That is, fine adjustment of the distance between the first substrate 60b and the second substrate 80b is facilitated in the sealing process.

[0081] Other Embodiments In the first embodiment, one type of frame spacer is provided only on the first substrate, and in the second embodiment, two types of frame spacers are provided on both the first substrate and the second substrate. As such, it is sufficient that the frame spacer is provided on at least the first substrate.

[0082] In each of the above embodiments, an organic EL layer having a five-layer stacked structure of a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer has been exemplified. However, the organic EL layer may have a three-layer stacked structure of, for example, a hole injection layer / hole transport layer, a light-emitting layer, and an electron transport layer / electron injection layer.

[0083] In addition, in each of the above embodiments, an organic EL display device in which the first electrode is an anode and the second electrode is a cathode is exemplified. However, the present invention can also be applied to an organic EL display device in which the stacked structure of the organic EL layer is reversed, and the first electrode is a cathode and the second electrode is an anode.

[0084] In each of the above embodiments, an organic EL display device is exemplified in which the electrode of the TFT connected to the first electrode is used as the drain electrode, but the present invention can also be applied to an organic EL display device in which the electrode of the TFT connected to the first electrode is called the source electrode.

[0085] In the above embodiments, an organic EL display device is used as the display device, but the present invention can also be applied to display devices such as an active matrix driving liquid crystal display device.

[0086] In the above embodiments, an organic EL display device has been described as an example of a display device, but the present invention is not limited to organic EL display devices and can be applied to any flexible display device. For example, the present invention can be applied to a flexible display device including a quantum-dot light emitting diode (QLED), which is a light emitting element using a quantum dot-containing layer.

[0087] As described above, the present invention is useful for flexible display devices.

[0088] D Display area F Frame area 10 Resin substrate (base substrate) 30 TFT (thin film transistor) layer 31 First electrode 32 Edge cover 33 Organic EL layer (organic electroluminescence layer, light-emitting functional layer) 34 Second electrode 35 Organic EL element (light-emitting element) 40 Organic EL element layer (light-emitting element layer) 50da Pixel spacer 50fa Frame spacer 50fba First frame spacer 50fbb Second frame spacer 60a, 60b First substrate 70 Glass substrate 71 First inorganic film 72 Second inorganic film 75 Inorganic laminated film 80a, 80b Second substrate 90a, 90b Organic EL display device

Claims

1. A display device having a display area and a frame area provided around the display area, comprising: a first substrate on which a plurality of light-emitting elements are provided corresponding to a plurality of sub-pixels that make up the display area; a second substrate arranged opposite the first substrate; and a plurality of pixel spacers arranged in the display area and a plurality of frame spacers arranged in the frame area, which are interposed between the first and second substrates, wherein the plurality of light-emitting elements of the first substrate are sealed by the second substrate via the plurality of pixel spacers and the plurality of frame spacers, and wherein the plurality of frame spacers are provided on at least the first substrate, and the plurality of pixel spacers are provided on the second substrate.

2. In the display device according to claim 1, the second substrate has a glass substrate, an inorganic laminated film provided on the glass substrate, and the plurality of pixel spacers, and the inorganic laminated film is a film made of SiNx and SiO ２ A display device characterized in that it is formed in a laminated film including a film.

3. In the display device according to claim 2, the inorganic laminated film is a SiNx film, SiO ２ Film and SiO ２ A display device characterized in that it is formed into a laminated film in which films are laminated in order.

4. The display device according to claim 2 or 3, wherein the plurality of pixel spacers are provided on the inorganic laminated film.

5. A display device according to any one of claims 1 to 4, wherein the plurality of light-emitting elements are formed by stacking a plurality of first electrodes, a common edge cover, a plurality of light-emitting functional layers and a common second electrode in this order, and the plurality of frame spacers are provided on the second electrode.

6. The display device according to claim 5, wherein the plurality of frame spacers are made of the same material as the edge cover.

7. The display device according to any one of claims 1 to 6, wherein the plurality of pixel spacers and the plurality of frame spacers are formed from an organic resin film.

8. The display device according to claim 7, wherein the plurality of pixel spacers and the plurality of frame spacers are made of the same material.

9. The display device according to claim 7, wherein the plurality of pixel spacers and the plurality of frame spacers are made of different materials.

10. A display device according to any one of claims 1 to 9, wherein the plurality of pixel spacers are provided between the plurality of sub-pixels.

11. The display device according to any one of claims 1 to 10, wherein the plurality of pixel spacers and the plurality of frame spacers have different densities.

12. A display device according to any one of claims 1 to 11, characterized in that the plurality of frame spacers include a plurality of first frame spacers provided on the first substrate, and a plurality of second frame spacers provided on the second substrate and arranged opposite the plurality of first frame spacers, respectively.

13. A display device according to claim 12, wherein the thickness of the first frame spacer and the second frame spacer is smaller than the thickness of the pixel spacer.

14. A display device according to claim 12 or 13, wherein the total thickness of the first frame spacer and the second frame spacer is approximately the same as the thickness of the pixel spacer.

15. A display device according to any one of claims 1 to 14, wherein the plurality of light-emitting elements are organic electroluminescence elements.

16. A display device according to any one of claims 1 to 14, wherein the plurality of light-emitting elements are quantum dot light-emitting elements.

Images