WO2026018380A1 - Display device - Google Patents

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

The present invention relates to a display device.

In recent years, organic electroluminescence (EL) display devices using organic electroluminescence (EL) elements (light-emitting elements) have been attracting attention as a self-luminous display device that can replace liquid crystal display devices. Development is also underway on quantum-dot light-emitting diode (QLED) display devices, which are light-emitting elements that use a quantum dot-containing layer. Self-luminous display devices are provided with multiple thin-film transistors (TFTs) and multiple light-emitting elements corresponding to the sub-pixels that make up the display area where images are displayed. Furthermore, in order to prevent deterioration of the multiple light-emitting elements due to the intrusion of moisture, oxygen, etc., a sealing structure has been proposed for self-luminous display devices in which a substrate (backplane substrate) on which the light-emitting elements are mounted is sealed with an opposing substrate that faces the substrate.

For example, Patent Document 1 proposes a display device that includes a first substrate, a second substrate, and a plurality of columnar spacers arranged between the first and second substrates.

JP 2009-237578 A

Incidentally, when the above-mentioned sealing structure is adopted in an organic EL display device or a QLED display device, as described in Patent Document 1, multiple spacers are generally provided on the backplane substrate (the first substrate in Patent Document 1). Because the multiple spacers are arranged between subpixels at a higher density than the multiple light-emitting elements, there is a risk that the spacers will reduce the luminance of the emitted light.

The present invention was made in light of these issues, and its purpose is to suppress the reduction in luminance caused by spacers in a display device having a sealing structure in which two opposing substrates are sealed via multiple spacers.

In order to achieve the above object, the display device of the present invention comprises a first substrate having a display area and a frame area surrounding the display area, and on which a plurality of light-emitting elements are provided corresponding to a plurality of sub-pixels constituting the display area; a second substrate disposed opposite the first substrate; and a plurality of pixel spacers disposed in the display area and a plurality of frame spacers disposed in the frame area, which are interposed between the first and second substrates. 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 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.

According to the present invention, in a display device having a sealing structure in which two opposing substrates are sealed via multiple spacers, it is possible to suppress the reduction in luminance caused by the spacers.

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 the display area 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. 4A to 4C are cross-sectional views 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 the 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 that constitutes the organic EL display device according to the first embodiment of the present invention. 9A to 9C are cross-sectional views showing a manufacturing process of an organic EL display device according to the second embodiment of the present invention, and correspond to FIG. FIG. 10 is a cross-sectional view showing a first substrate constituting an organic EL display device according to a second embodiment of the present invention, and corresponds to FIG. FIG. 11 is a cross-sectional view showing a second substrate constituting an organic EL display device according to a second embodiment of the present invention, and corresponds to FIG.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the following embodiments.

First Embodiment
FIGS. 1 to 8 illustrate 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.

<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 in the direction Z indicates that the second substrate 80a is positioned above the first substrate 60a in the organic EL display device 90a.

In the display region D, as shown in FIG. 2, a plurality of sub-pixels P are arranged in a matrix. Also, in the display region D, as shown in FIG. 2, 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. Note that in the display region D, one pixel is made up of, for example, three adjacent sub-pixels P having a red light-emitting region Lr, a green light-emitting region Lg, and a blue light-emitting region Lb. Note that the arrangement of the sub-pixels P is not particularly limited, and examples include a pentatile arrangement and a stripe arrangement.

A terminal portion T is provided at one end (the right end in Figure 1) of the frame region F, extending in one direction (direction Y, the vertical direction in Figure 1). A folding portion (not shown) that can be folded, for example, 180 degrees (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, extending in one direction (direction Y).

As shown in FIG. 3, the organic EL display device 90a comprises 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.

The first substrate 60a is a backplane substrate equipped with a plurality of organic EL elements 35 (light-emitting elements) (described below) that constitute the display area 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 area D. The pixel spacers 50da are provided between the plurality of subpixels P that constitute the display area D. The frame spacers 50fa are photospacers disposed in the frame area F.

As shown in FIG. 3, the pixel spacers 50da and 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 frame spacers 50fa have approximately the same thickness (dimension in direction Z). Multiple pixel spacers 50da and multiple frame spacers 50fa are arranged, for example, in an island-like pattern at equal intervals. The multiple pixel spacers 50da and multiple 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 multiple pixel spacers 50da arranged at high density corresponding to the multiple sub-pixels P may be set higher than the density of the multiple frame spacers 50fa.

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

As shown in FIG. 3, the multiple organic EL elements 35 constituting the first substrate 60a are sealed by the second substrate 80a via multiple pixel spacers 50da and multiple 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 multiple pixel spacers 50da and multiple frame spacers 50fa.

The sealing structure between the first substrate 60a and the second substrate 80a is not particularly limited, and examples include a structure in which they 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 edge of the frame area F so as to surround the display area 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 epoxy resin, acrylic resin, silicone resin, or fluororesin.

Incidentally, in conventional display devices having the above-mentioned sealing structure, multiple spacers are typically provided on the backplane substrate. That is, both the multiple spacers arranged in the display area and the multiple spacers arranged in the frame area are provided on the same backplane substrate. The multiple spacers arranged in the display area are arranged between subpixels at a higher density than the multiple light-emitting elements. The light-emitting element layer formed on the multiple spacers arranged at a high density in the display area is affected by the unevenness caused by the spacers and is formed in an uneven shape. Therefore, in conventional display devices, the spacers arranged in the display area reduce the luminance of emitted light.

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

In the organic EL display device 90a having the above-described sealing structure, as shown in Figures 4 and 5, in the display region D, the first substrate 60a, which is the backplane substrate, does not have the pixel spacers 50da, which form structural elements. In other words, the pixel spacers 50da do not exist 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, the reduction in luminance due to the pixel spacers 50da arranged in the display region D is suppressed.

In the organic EL display device 90a having the above-described sealing structure, the bonding precision 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 place the alignment spacers in the desired position on the second substrate 80a. On the other hand, the multiple frame spacers 50fa provided on the first substrate 60a can achieve high alignment precision, so by using multiple frame spacers 50fa (one or more of which are alignment spacers), it is easy to place the alignment spacers in the desired position on the first substrate 60a.

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 spacers than the second substrate 80a. Therefore, by forming the spacers as a laminated film, for example, the thickness of the frame spacer 50fa can be formed with relative freedom.

<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.

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

As shown in FIG. 5, the TFT layer 30 comprises a base coat film 11 provided on a resin substrate 10, a plurality of first TFTs 9a, a plurality of second TFTs 9b, a plurality of third TFTs 9c, and a plurality of capacitors 9d provided on the base coat film 11 for each subpixel 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 9a, second TFTs 9b, third TFTs 9c, and capacitors 9d.

As shown in Figure 5, the TFT layer 30 includes, on a resin substrate 10, 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 Figures 2 and 7), the light-emitting control line 14e (see Figures 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 Figures 2 and 7), the power line 18g (see Figures 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, which are stacked in this order.

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 are each composed of a single layer or a stacked layer of inorganic insulating films such as silicon nitride (SiNx (x is a positive number)), silicon oxide (SiO ₂ ), or silicon oxynitride (SiON). The semiconductor layers 12a and 12b are each composed of 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 a metal single layer film such as molybdenum (Mo), titanium (Ti), aluminum (Al), copper (Cu), or tungsten (W), or a metal stacked layer film such as Mo (upper layer)/Al (middle layer)/Mo (lower layer), Ti/Al/Ti, Al (upper layer)/Ti (lower layer), Cu/Mo, or Cu/Ti.

2, the TFT layer 30 is provided with a plurality of gate lines 14g extending parallel to each other in the X direction in the figure. The TFT layer 30 is also provided with a plurality of light-emitting control lines 14e extending parallel to each other in the X direction in the figure. Each light-emitting control line 14e is arranged adjacent to each gate line 14g. The TFT layer 30 is also provided with a plurality of source lines 18f extending parallel to each other 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 each other in the Y direction in the figure. Each power supply line 18g is arranged adjacent to each 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, second TFT 9b, and third TFT 9c are p-type TFTs in which the semiconductor layers 12a, 12b, etc. are doped with impurities such as boron.

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 an oxide semiconductor, such as an In-Ga-Zn-O system, and are provided in island shapes on the base coat film 11 as shown in FIG. 5. The semiconductor layers 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.

As shown in FIG. 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 third TFT 9c.

As shown in FIG. 7, in each subpixel P, the third TFT 9c is electrically connected to the corresponding second TFT 9b, the first electrode 31 of the organic EL element 35 (described later), and the light-emitting 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 on the second interlayer insulating film 17. The gate electrode 14b is arranged to overlap the channel region of the semiconductor layer 12b and controls the 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 via contact holes formed in the stack of the gate insulating film 13, the first interlayer insulating film 15, and the second interlayer insulating film 17.

In this embodiment, the first TFT 9a, second TFT 9b, and third TFT 9c are illustrated as top-gate types, but the first TFT 9a, second TFT 9b, and third TFT 9c may also be bottom-gate types.

As shown in FIG. 7, in each subpixel P, the capacitor 9d is electrically connected to the corresponding first TFT 9a and power supply line 18g. As shown in FIG. 5, the capacitor 9d includes a lower conductive layer 14c formed from a first metal film, a first interlayer insulating film 15 provided to cover the lower conductive layer 14c, and an upper conductive layer 16c formed from a second metal film on the first interlayer insulating film 15 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.

The first planarization film 20 and the second planarization film 22 have flat surfaces in the display area 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.

As shown in FIG. 5, a relay electrode 21 formed in the same layer as the fourth metal film and made of the same material is provided between the first planarization film 20 and the second planarization film 22. As shown in FIG. 5, the relay electrode 21 is electrically connected to the drain electrode 18d of the third TFT 9c via a first contact hole Ha formed in the laminated film of the first inorganic insulating film 19 and the first planarization film 20.

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

As shown in FIG. 5, the organic EL element 35 comprises 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 subpixel P, and a second electrode 34 arranged on the organic EL layer 33 in common to the plurality of subpixels P.

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. 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). The material constituting the first electrode 31 may be an alloy such as astatine (At)/astatine oxide (AtO ₂ ). Furthermore, the material constituting the first electrode 31 may be a conductive oxide such as tin oxide (SnO), zinc oxide (ZnO), indium tin oxide (ITO), or indium zinc oxide (IZO). The first electrode 31 may also 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).

The peripheral edge of the first electrode 31 is covered by an edge cover 32 provided in a grid pattern and shared by multiple sub-pixels P. Examples of materials that can be used to form the edge cover 32 include positive photosensitive resin materials such as polyimide resin, acrylic resin, polysiloxane resin, and novolac resin, as well as polysiloxane-based SOG materials.

As shown in FIG. 5, the organic EL layer 33 is disposed on each first electrode 31 and is arranged in a matrix to correspond to a plurality of subpixels P. Here, as shown in FIG. 8, 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 arranged in this order on the first electrode 31.

The hole injection layer 1, also known as an anode buffer layer, functions to bring the energy levels of the first electrode 31 and the organic EL layer 33 closer together, improving the efficiency of hole injection from the first electrode 31 to the organic EL layer 33. Examples of materials that can be used to form 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.

The hole transport layer 2 functions to improve the efficiency of hole transport from the first electrode 31 to the organic EL layer 33. Examples of materials that can be used to form 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.

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 by the first electrode 31 and the second electrode 34. Here, the light-emitting layer 3 is formed from a material with high luminous efficiency. Examples of materials that can be used to form 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.

The electron transport layer 4 has the function of efficiently transporting electrons to the light-emitting layer 3. Examples of materials that can be used to form 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.

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. Examples of materials that can be used to form the electron injection layer 5 include inorganic alkali compounds such as lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), calcium fluoride (CaF ₂ ), strontium fluoride (SrF ₂ ), and barium fluoride (BaF ₂ ), aluminum oxide (Al ₂ O ₃ ), and strontium oxide (SrO).

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 formed of an alloy such as magnesium (Mg)/copper (Cu), magnesium (Mg)/silver (Ag), sodium (Na)/potassium (K), astatine (At)/astatine oxide (AtO ₂ ), 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 small 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).

As shown in FIG. 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 mentioned above, the frame spacer 50fa is not provided in the display region D.

In the first substrate 60a described above, in each subpixel 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 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 on the first substrate 60a, even when the first TFT 9a is turned off, the gate voltage of the second TFT 9b is held by the capacitor 9d, so light emission by the light-emitting layer 3 is maintained in each subpixel P until the gate signal for the next frame is input.

<Second substrate>
As shown in Figure 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.

The glass substrate 70 is a plate that forms the base of the second substrate 80a. In other words, the second substrate 80a is a substrate that glass-seals the first substrate 60a.

In conventional display devices having the above-described sealing structure, silicon nitride (SiNx (x is a positive number) ₎ such as trisilicon tetranitride ( _Si3N4 ) is generally deposited on the entire surface of the glass substrate serving as the opposing substrate as an inorganic film to block impurities, moisture, and the like from the glass substrate. Deposition of the SiNx film causes the opposing substrate to become colored. Therefore, in conventional display devices, the emission brightness decreases due to the coloration of the opposing substrate.

In contrast, in the organic EL display device 90a, the inorganic laminate film 75 provided on the glass substrate 70 of the second substrate 80a is formed as a laminate film including a silicon nitride (SiNx (x is a positive number)) film and a silicon oxide ( _SiO2 ) film. The _SiO2 film reduces coloration of the second substrate 80a caused by the SiNx film and improves transmittance. Therefore, in the organic EL display device 90a, a decrease in luminance caused by coloration of the second substrate 80a is suppressed.

The inorganic laminated film 75 is preferably configured as a laminated film (SiO2 film/ _SiO2 film/ _SiNx film) in which a SiNx film, a _SiO2 film, and a _SiO2 film are laminated in this order. As shown in FIG. 6, the inorganic laminated film 75 is 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 formed as a laminated film in which a SiNx film and a _SiO2 film are laminated in this order ( _SiO2 film/SiNx film = 50 nm/50 nm). The second inorganic film 72 is formed as a single layer film of a _SiO2 film (50 nm). The thicknesses of the SiNx film and the _SiO2 film are not limited to those described above and may be set to optimal values, for example, by optical simulation.

The inorganic laminated film 75 may include a film made of an inorganic material such as aluminum oxide (Al ₂ O ₃ ) or silicon carbonitride (SiCN) as long as it does not impede the object of the present invention.

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).

As shown in FIG. 6, pixel spacer 50da is provided on inorganic laminate film 75 in display region D. Specifically, pixel spacer 50da is provided on second inorganic film 72 that constitutes inorganic laminate film 75 in display region D. As mentioned above, pixel spacer 50da is not provided in frame region F.

<Method of manufacturing an 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.

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

(TFT layer formation process)
For example, a base coat film 11, a first TFT 9a, a second TFT 9b, a third TFT 9c, a capacitor 9d, 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.

(Organic EL element layer forming 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.

(First spacer forming step)
In the frame region F, a film of an organic resin material is formed by a well-known method on the second electrode 34 of the organic EL element layer 40 formed in the organic EL element layer formation step, 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.

Finally, a protective sheet (not shown) is attached to the surface of the substrate, and then laser light is applied 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 these steps, the first substrate 60a can be manufactured.

[Second substrate forming process]
The second substrate forming step includes an inorganic laminate film forming step and a second spacer forming step.

(Inorganic laminated film forming process)
For example, a first inorganic film 71, which is a laminated film ( _SiO2 film/SiNx film=50 nm/50 nm) in which a SiNx film and a _SiO2 film are laminated in this order from the bottom, and a second inorganic film 72, which is a single layer film of a _SiO2 film (50 nm), are formed in this order on the surface of a glass substrate 70 as a base substrate using a well-known method, to form an inorganic laminated film 75.

(Second spacer forming step)
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 formation process, and then the organic resin film is patterned to form a plurality of pixel spacers 50da. Through the above steps, the second substrate 80a can be manufactured.

[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.

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

<Effects>
As described above, the organic EL display device 90a of this embodiment can provide the following effects.
(1) The organic EL display device 90a has a sealing structure that seals two opposing substrates, a first substrate 60a (backplane substrate) and a 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 as a laminated film including a SiNx film and a _SiO2 film, and the thicknesses of the films are optimized (for example, _SiO2 film/ _SiO2 film/SiNx film = 50 nm/50 nm/50 nm). This suppresses coloring of the second substrate 80a caused by the SiNx film, and further suppresses a decrease in luminance.
(3) In the organic EL display device 90a, the film configuration of the substrate on which the pixel spacer 50da is formed and the second substrate 80a is optimized due to the above (1) and (2), improving the optical transmittance and, as a result, improving the quality of the display device.

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 and 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.

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

As shown in Figures 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. Note that, like the first substrate 60a, the first substrate 60b, which is a backplane substrate, does not have a plurality of pixel spacers 50da, which form structures, formed in the display region D. The frame spacers 50fba are thinner than the frame spacers 50fa of the first substrate 60a.

As shown in Figures 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. In other words, the second substrate 80b has two types of spacers: pixel spacers 50da in the display region D and second frame spacers 50fbb in the frame region F. In the frame region F, the second substrate 80a does not have any spacers, whereas the second substrate 80b has a plurality of second frame spacers 50fbb.

As shown in Figures 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 total thickness 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.

The organic EL display device 90b can be produced by modifying the first substrate formation process and second substrate formation process of the organic EL display device 90a described above as follows:

[First Substrate Forming Process (First Spacer Forming Process)]
In the first spacer formation step of the first substrate formation step, 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, thereby forming a first substrate 60b having a plurality of first frame spacers 50fba.

[Second Substrate Forming Process (Second Spacer Forming Process)]
In the second spacer formation step of the second substrate formation step, when the pixel spacers 50da are formed 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 laminate 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.

<Effects>
According to the organic EL display device 90b described above, in addition to the effects of the organic EL display device 90a described above, the following effects can be obtained.
(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 plurality of first frame spacers 50fba. This facilitates fine adjustment of the thickness T1 of the plurality of first frame spacers 50fba and the thickness T2 of the plurality of second frame spacers 50fbb arranged in the frame region F, and the thickness T3 of the plurality of 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.

Other Embodiments
In the first embodiment described above, one type of frame spacer is provided only on the first substrate, and in the second embodiment described above, two types of frame spacers are provided on both the first substrate and the second substrate, so it is sufficient that the frame spacer is provided on at least the first substrate.

In 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 is exemplified. However, the organic EL layer may also 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.

Furthermore, while the above embodiments illustrate organic EL display devices in which the first electrode serves as an anode and the second electrode serves as a cathode, the present invention can also be applied to organic EL display devices in which the layered structure of the organic EL layer is reversed, with the first electrode serving as a cathode and the second electrode serving as an anode.

In the above embodiments, an organic EL display device was exemplified in which the electrode of the TFT connected to the first electrode was 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.

In the above embodiments, an organic EL display device was used as the display device, but the present invention can also be applied to display devices such as active matrix drive liquid crystal display devices.

In the above embodiments, an organic EL display device has been used 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 equipped with a QLED (Quantum-dot light emitting diode), which is a light emitting element that uses a quantum dot-containing layer.

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

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 films 80a, 80b second substrate 90a, 90b organic EL display device

Claims (16)

a display area and a frame area provided around the display area;
a first substrate on which a plurality of light-emitting elements are provided corresponding to a plurality of sub-pixels constituting the display area;
a second substrate disposed opposite the first substrate;
a plurality of pixel spacers disposed in the display region and a plurality of frame spacers disposed in the frame region, the plurality of pixel spacers being interposed between the first substrate and the second substrate;
a display device in which 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,
the plurality of frame spacers are provided on at least the first substrate,
The display device, wherein the plurality of pixel spacers are provided on the second substrate. 2. The display device according to claim 1,
the second substrate includes a glass substrate, an inorganic stacked film provided on the glass substrate, and the plurality of pixel spacers;
The display device is characterized in that the inorganic laminated film is formed as a laminated film including a SiNx film and a _SiO2 film. 3. The display device according to claim 2,
The display device is characterized in that the inorganic laminated film is formed as a laminated film in which a SiNx film, a SiO ₂ film, and a SiO ₂ film are laminated in this order. 4. The display device according to claim 2 or 3,
The display device is characterized in that the plurality of pixel spacers are provided on the inorganic laminated film. The display device according to any one of claims 1 to 4,
The plurality of light-emitting elements are formed by sequentially stacking a plurality of first electrodes, a common edge cover, a plurality of light-emitting functional layers, and a common second electrode,
The display device is characterized in that the plurality of frame spacers are provided on the second electrode. 6. The display device according to claim 5,
The display device is characterized in that the plurality of frame spacers are formed from the same material as the edge cover. The display device according to any one of claims 1 to 6,
The display device, 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,
The display device, wherein the plurality of pixel spacers and the plurality of frame spacers are formed from the same material. 8. The display device according to claim 7,
The display device, wherein the plurality of pixel spacers and the plurality of frame spacers are formed from different materials. The display device according to any one of claims 1 to 9,
The display device, wherein the plurality of pixel spacers are provided between the plurality of sub-pixels. The display device according to any one of claims 1 to 10,
The display device is characterized in that the plurality of pixel spacers and the plurality of frame spacers have different densities. The display device according to any one of claims 1 to 11,
The plurality of frame spacers are
a plurality of first frame spacers provided on the first substrate;
a plurality of second frame spacers provided on the second substrate and arranged to face the plurality of first frame spacers, respectively. 13. The display device according to claim 12,
The display device, wherein the thickness of the first frame spacer and the second frame spacer is smaller than the thickness of the pixel spacer. 14. The display device according to claim 12 or 13,
A display device, 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. The display device according to any one of claims 1 to 14,
The display device is characterized in that the plurality of light-emitting elements are organic electroluminescence elements. The display device according to any one of claims 1 to 14,
The display device is characterized in that the plurality of light-emitting elements are quantum dot light-emitting elements.