Indication device

Abstract

The present invention provides a display device in which liquid accumulation near the partition wall is reduced when forming the light-emitting layer using a wet method. [Solution] The display device comprises a first anode, a second anode adjacent to the first anode in the X direction, a third anode adjacent to the first anode in the Y direction, a hole injection layer extending from the first anode to the third anode, a partition wall provided on the hole injection layer, a first light-emitting layer, a second light-emitting layer, a third light-emitting layer, and a cathode, wherein the partition wall has a first region located between the first anode and the third anode and extending in the X direction in a top view, and a second region located between the first anode and the second anode and extending in the Y direction, and in a cross-sectional view, the height of the first region is greater than the height of the second region.

Description

Technical Field

[0001] One aspect of the present invention relates to a display device and a method for manufacturing the same.

[0002] Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification or the like relates to an article, a method, or a manufacturing method. Alternatively, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. As a more specific technical field of one aspect of the present invention disclosed in this specification or the like, a semiconductor device, a display device, a light-emitting device, a power storage device, and a storage device can be cited as examples, and driving methods for these or manufacturing methods for these can also be cited as examples.

Background Art

[0003] As a method for manufacturing a display device including an organic EL, there is an inkjet method in which a solution containing a light-emitting material is dropped and a solvent is volatilized from the solution to form a light-emitting layer. A method for forming a light-emitting layer by an inkjet method and eliminating a baking process for a solution is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In FIG. 3(A) of Patent Document 1 described above, a state in which a solution is dropped into a region partitioned by an insulator for each pixel is shown, and a liquid pool immediately after dropping is shown. In such a liquid pool, since a solvent evaporates, it is disclosed in Patent Document 1 that the baking process can be eliminated by using a coating process.

[0006] However, it is difficult to eliminate the firing process. When firing is carried out in a reduced-pressure atmosphere, liquid pools remain near the insulators, that is, the partition walls. Due to the current concentrating in the center of the light-emitting area and the current density becoming non-uniform due to such liquid pools, the inventors considered that suppressing liquid pools is important for providing a high-definition display device.

[0007] In view of the above, one aspect of the present invention provides a display device formed by a wet method including an inkjet method or the like, having a configuration in which liquid pools are reduced and a method for manufacturing the same.

[0008] Note that the description of these problems does not prevent the existence of other problems. Note that one aspect of the present invention does not need to solve all of these problems. Note that other problems will be apparent from the description in the specification, drawings, claims, etc. (referred to as this specification, etc.), and it is possible to extract other problems from the description in this specification, etc.

Means for Solving the Problems

[0009] In view of the above problems, one aspect of the present invention includes a first anode, a second anode adjacent to the first anode in the X direction, a third anode adjacent to the first anode in the Y direction, a hole injection layer provided over the first anode to the third anode, a partition wall provided over the hole injection layer, a first light-emitting layer positioned in a first opening of the partition wall and overlapping with the first anode, a second light-emitting layer positioned in a second opening of the partition wall and overlapping with the second anode, a third light-emitting layer positioned in a third opening of the partition wall and overlapping with the third anode, and a cathode provided over the first light-emitting layer to the third light-emitting layer. The partition wall has a first region positioned between the first anode and the third anode and extending in the X direction and a second region positioned between the first anode and the second anode and extending in the Y direction in a top view, and a height in the first region is larger than a height in the second region in a cross-sectional view.

[0010] Another aspect of the present invention comprises a first anode, a second anode adjacent to the first anode in the X direction, a third anode adjacent to the first anode in the Y direction, a hole injection layer extending across the first to third anodes, a partition wall provided on the hole injection layer, a first light-emitting layer located at a first opening of the partition wall and overlapping with the first anode, a second light-emitting layer located at a second opening of the partition wall and overlapping with the second anode, and a third opening of the partition wall. The display device has a third light-emitting layer positioned and overlapping with the third anode, and a cathode provided across the first to third light-emitting layers, and the partition wall has a first region located between the first anode and the third anode in a top view and extending in the X direction, and a second region located between the first anode and the second anode and extending in the Y direction, and in a cross-sectional view the height of the second region is greater than the height of the first region.

[0011] Another aspect of the present invention comprises a first anode, a second anode adjacent to the first anode in the X direction, a third anode adjacent to the first anode in the Y direction, a hole injection layer extending across the first to third anodes, a partition wall provided on the hole injection layer, a first light-emitting layer located at a first opening of the partition wall and overlapping with the first anode, a second light-emitting layer located at a second opening of the partition wall and overlapping with the second anode, and a third light-emitting layer located at a third opening of the partition wall and overlapping with the third anode. The display device comprises an overlapping third light-emitting layer and a cathode extending across the first to third light-emitting layers, wherein the partition wall has a first region located between the first anode and the third anode in a top view and extending in the X direction, and a second region located between the first anode and the second anode and extending in the Y direction, and in a cross-sectional view the height of the first region is greater than the height of the second region, and the partition wall has a stacked structure in the first region.

[0012] Another aspect of the present invention comprises a first anode, a second anode adjacent to the first anode in the X direction, a third anode adjacent to the first anode in the Y direction, a hole injection layer extending across the first to third anodes, a partition wall provided on the hole injection layer, a first light-emitting layer located at a first opening of the partition wall and overlapping with the first anode, a second light-emitting layer located at a second opening of the partition wall and overlapping with the second anode, and a third light-emitting layer located at a third opening of the partition wall and overlapping with the third anode. The display device comprises an overlapping third light-emitting layer and a cathode extending across the first to third light-emitting layers, wherein the partition wall has a first region located between the first anode and the third anode in a top view and extending in the X direction, and a second region located between the first anode and the second anode and extending in the Y direction, and in a cross-sectional view the height of the second region is greater than the height of the first region, and the partition wall has a stacked structure in the second region.

[0013] In one embodiment of the present invention, the partition wall having a laminated structure preferably comprises a first partition wall having an inorganic material and a second partition wall having an organic material located on the first partition wall.

[0014] In one embodiment of the present invention, it is preferable that a hole transport layer is provided between the hole injection layer and the partition wall.

[0015] In one embodiment of the present invention, the hole injection layer preferably contains molybdenum oxide.

[0016] In one embodiment of the present invention, it is preferable that the ends of the first to third anodes each have a tapered shape.

[0017] Another aspect of the present invention involves forming a first anode, a second anode adjacent to the first anode in the X direction, and a third anode adjacent to the first anode in the Y direction, forming a hole injection layer across the first to third anodes, forming a partition on the hole injection layer having a first opening overlapping the first anode, a second opening overlapping the second anode, and a third opening overlapping the third anode, and applying an inkjet method to any one of the first light-emitting layer located at the first opening, the second light-emitting layer located at the second opening, or the third light-emitting layer located at the third opening. A method for manufacturing a display device, wherein a cathode is formed across a first to third light-emitting layer, the partition wall having a first region located between the first anode and the third anode in a top view and extending in the X direction, and a second region located between the first anode and the second anode and extending in the Y direction, the height of the first region being greater than the height of the second region in a cross-sectional view, and the method for manufacturing a display device wherein the first light-emitting layer and the third light-emitting layer are formed by an inkjet method while moving along the first region.

[0018] Another aspect of the present invention involves forming a first anode, a second anode adjacent to the first anode in the X direction, and a third anode adjacent to the first anode in the Y direction, forming a hole injection layer across the first to third anodes, forming a partition on the hole injection layer having a first opening overlapping the first anode, a second opening overlapping the second anode, and a third opening overlapping the third anode, and applying an inkjet method to any one of the first light-emitting layer located at the first opening, the second light-emitting layer located at the second opening, or the third light-emitting layer located at the third opening. A method for manufacturing a display device, wherein a cathode is formed across a first to third light-emitting layer, the partition wall having a first region located between the first anode and the third anode in a top view and extending in the X direction, and a second region located between the first anode and the second anode and extending in the Y direction, the height of the second region being greater than the height of the first region in a cross-sectional view, and the method for manufacturing a display device wherein the first light-emitting layer and the third light-emitting layer are formed by an inkjet method while moving along the second region.

[0019] In one embodiment of the present invention, it is preferable to form a hole transport layer on a hole injection layer and to form a partition wall on the hole transport layer. [Effects of the Invention]

[0020] According to one aspect of the present invention, a display device that suppresses liquid accumulation and a method for manufacturing the same can be provided.

[0021] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one embodiment of the present invention does not necessarily have to possess all of these effects. Other effects will become clear from the description in this specification, and it is possible to extract other effects from the description in this specification. [Brief explanation of the drawing]

[0022] [Figure 1] Figure 1 is a perspective view illustrating a pixel region according to one embodiment of the present invention. [Figure 2] Figures 2A and 2B are cross-sectional views illustrating a pixel region according to one embodiment of the present invention. [Figure 3] Figures 3A to 3C are cross-sectional views illustrating a pixel region according to one embodiment of the present invention. [Figure 4] Figure 4 is a cross-sectional view illustrating a method for manufacturing a pixel region according to one embodiment of the present invention. [Figure 5] Figure 5 is a perspective view illustrating a pixel region according to one embodiment of the present invention. [Figure 6] Figure 6 is a perspective view illustrating a pixel region according to one embodiment of the present invention. [Figure 7] Figures 7A and 7B are cross-sectional views illustrating a pixel region according to one embodiment of the present invention. [Figure 8] Figures 8A to 8C are cross-sectional views illustrating a pixel region according to one embodiment of the present invention. [Figure 9] Figure 9 is a cross-sectional view illustrating a method for fabricating a pixel region according to one embodiment of the present invention. [Figure 10] Figure 10 is a perspective view illustrating a pixel region according to one embodiment of the present invention. [Figure 11] Figures 11A to 11D2 are cross-sectional views illustrating a light-emitting element according to one embodiment of the present invention. [Figure 12] Figures 12A to 12D are circuit diagrams illustrating a pixel circuit according to one embodiment of the present invention. [Figure 13] Figures 13A to 13D are circuit diagrams illustrating a pixel circuit according to one embodiment of the present invention. [Figure 14] Figure 14 is a diagram illustrating a method for driving a pixel circuit according to one aspect of the present invention. [Figure 15] Figure 15 is a perspective view showing an example of a display device. [Figure 16] Figures 16A and 16B are cross-sectional views showing an example of a display device. [Figure 17] Figure 17 is a cross-sectional view showing an example of a display device. [Figure 18] Figure 18A is a cross-sectional view showing an example of a display device. Figure 18B is a cross-sectional view showing an example of a transistor. [Figure 19] Figures 19A and 19B are cross-sectional views showing an example of a display device. [Figure 20] Figure 20 is a cross-sectional view showing an example of a display device. [Figure 21] Figure 21A is a cross-sectional view showing an example of a display device. Figure 21B is a cross-sectional view showing an example of a transistor. [Figure 22] Figures 22A and 22B show examples of electronic devices. [Figure 23] Figures 23A to 23D show examples of electronic devices. [Figure 24] Figures 24A to 24F show examples of electronic devices. [Figure 25] Figures 25A to 25F show examples of electronic devices. [Modes for carrying out the invention]

[0023] In the drawings attached to this specification, components are sometimes classified by function and explained using independent block diagrams. However, in reality, it is difficult to completely separate components by function, and a single component may be involved in multiple functions.

[0024] In this specification, the terms "source" and "drain" of a transistor are reversed depending on the transistor's polarity and the potential applied to each terminal. Generally, in an n-channel transistor, the terminal to which a low potential is applied is called the source, and the terminal to which a high potential is applied is called the drain. In a p-channel transistor, the terminal to which a low potential is applied is called the drain, and the terminal to which a high potential is applied is called the source. In this specification, for convenience, the connection relationships of a transistor may be explained assuming that the source and drain are fixed, but in reality, the terms "source" and "drain" are reversed according to the potential relationship described above.

[0025] In this specification, the source of a transistor refers to the source region, which is part of the semiconductor film that functions as the active layer, or the source electrode connected to the semiconductor film. Similarly, the drain of a transistor refers to the drain region, which is part of the semiconductor film, or the drain electrode connected to the semiconductor film. The gate refers to the gate electrode.

[0026] In this specification, the state in which transistors are connected in series means, for example, a state in which only one of the sources or drains of the first transistor is connected to only one of the sources or drains of the second transistor. The state in which transistors are connected in parallel means a state in which one of the sources or drains of the first transistor is connected to one of the sources or drains of the second transistor, and the other of the sources or drains of the first transistor is connected to the other of the sources or drains of the second transistor.

[0027] In this specification, "connection" refers to an electrical connection, corresponding to a state in which current, voltage, or potential can be supplied or transmitted. Therefore, a connected state does not necessarily refer to a directly connected state, but also includes a state indirectly connected through circuit elements such as wiring, resistors, diodes, and transistors, so that current, voltage, or potential can be supplied or transmitted.

[0028] In this specification, even when components that appear independent in a circuit diagram are connected, in reality, a single conductive layer may combine the functions of multiple components, for example, when a portion of the wiring functions as an electrode. In this specification, connection includes such cases where a single conductive layer combines the functions of multiple components.

[0029] In this specification and other documents, the first and second electrodes of a transistor may be used in explanations; however, if one of the first and second electrodes is the source electrode, the other refers to the drain electrode.

[0030] In this specification, a light-emitting element has a structure in which a layer containing an organic compound (referred to as an organic compound layer) is sandwiched between a pair of electrodes. One of the pair of electrodes is the anode, the other is the cathode, the organic compound layer is a functional layer, and one of the functional layers is a light-emitting layer. A structure in which the functional layers form a laminate and have at least a light-emitting layer may be referred to as a light-emitting unit. In this specification, a light-emitting element may also be referred to as a light-emitting device.

[0031] In this specification and other documents, light-emitting devices that do not use a metal mask or a fine metal mask (FMM) may be referred to as light-emitting devices having a metal maskless (MML) structure.

[0032] In this specification, a structure in which the light-emitting layers are painted separately for each color of light-emitting element (e.g., red (R), green (G), and blue (B)) may be referred to as an SBS (Side By Side) structure. Furthermore, in this specification, a light-emitting element capable of emitting white light may be referred to as a white light-emitting element. A white light-emitting element can be combined with a colored layer (e.g., a color filter) to create a full-color display device.

[0033] In this specification, light-emitting devices can be broadly classified into single structures and tandem structures. A single structure has one light-emitting unit between a pair of electrodes, and this light-emitting unit has one or more light-emitting layers. In a single structure, to obtain white light emission, one should select light-emitting layers such that the light emitted from each of the two or more layers is complementary in color. For example, by making the light-emitting color of the first light-emitting layer and the light-emitting color of the second light-emitting layer complementary, a configuration in which the entire light-emitting device emits white light can be obtained. The same applies to light-emitting devices having three or more light-emitting layers.

[0034] A tandem structure has two or more light-emitting units between a pair of electrodes, and each light-emitting unit has one or more light-emitting layers. To obtain white light emission, the light from the light-emitting layers of the two or more light-emitting units is combined to produce white light emission. The configuration for obtaining white light emission is the same as that for a single structure. In a tandem structure, it is preferable to provide intermediate layers, such as charge-generating layers, between the multiple light-emitting units.

[0035] Furthermore, when comparing the aforementioned white light-emitting elements (single and tandem structures) with SBS structure light-emitting elements, SBS structure light-emitting elements can consume less power than white light-emitting elements. If you want to keep power consumption low, it is preferable to use SBS structure light-emitting elements. On the other hand, white light-emitting elements are preferable because their manufacturing process is simpler than that of SBS structure light-emitting elements, which can lead to lower manufacturing costs or higher manufacturing yields.

[0036] Next, embodiments will be described in detail with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and that its form and details can be modified in various ways without departing from the spirit and scope of the present invention. Accordingly, the present invention is not to be interpreted as being limited to the contents of the embodiments shown below. In the configuration of the invention described below, the same reference numerals are used in common across different drawings for the same parts or parts having similar functions, and repeated explanations are omitted.

[0037] (Embodiment 1) This embodiment describes a display device according to one aspect of the present invention. The display device has a light-emitting element, and the light-emitting element has a hole injection layer having a hole injection material, a hole transport layer having a hole transport material, a light-emitting layer having a light-emitting material, an electron transport layer having an electron transport material, or an electron injection layer having an electron injection material, etc. In one aspect of the present invention, any of the above layers can be manufactured by a wet process. This embodiment mainly describes the case in which the light-emitting layer is manufactured by a wet process.

[0038] A wet process is a method of obtaining a liquid composition by liquefying a material having a predetermined function by dissolving or dispersing it in a solvent, and then applying the liquid composition. After application, it solidifies or becomes a thin film through a drying or curing process. The liquid composition is sometimes referred to as a solution. Typical wet processes include spin coating, inkjet, casting, printing, dispensing, and spraying.

[0039] One embodiment of the present invention is characterized by the height of the partition wall, etc. Furthermore, two configuration examples of the present invention will be described: Configuration Example 1, in which the hole injection layer is located below the partition wall, and Configuration Example 2, in which both the hole injection layer and the hole transport layer are located below the partition wall.

[0040] <Configuration Example 1> Figure 1 shows an example of a perspective view of a display device, Figures 2A to 3C show examples of cross-sectional views of a display device, Figure 4 shows an example of a light-emitting layer fabrication, and Figure 5 shows an example of a perspective view of a display device different from Figure 1.

[0041] As shown in Figure 1, the display device has a pixel region 100 provided with light-emitting elements, and also has a drive circuit region and the like. The pixel region 100 has multiple pixels, and each pixel has multiple subpixels. A pixel is the smallest unit capable of full-color display, and when full-color display is achieved with red, green, and blue, in a top view (sometimes referred to as a plan view), one of the multiple subpixels can correspond to the light-emitting region of a red light-emitting element, another to the light-emitting region of a green light-emitting element, and another to the light-emitting region of a blue light-emitting element.

[0042] Although not shown in Figure 1, each sub-pixel also has a transistor electrically connected to each light-emitting element, and the light-emitting elements can be controlled using the transistor. A display device having such a structure is called an active-matrix display device, and one aspect of the present invention, such as Configuration Example 1, can be applied to it. Of course, one aspect of the present invention, such as Configuration Example 1, can also be applied to a passive-matrix display device.

[0043] When describing the configuration of the pixel region 100, the X direction and the Y direction, which intersects the X direction, may be used, as shown in Figure 1. For example, the X direction is the direction along the wiring to which the gate signal is supplied, and the Y direction is the direction along the wiring to which the source signal is supplied.

[0044] Figure 1 shows the pixel region 100, which includes an insulating film 101, an anode 102, a hole injection layer 104, a partition wall 110, a light-emitting layer 115, etc. The partition wall 110 includes a first region 110x and a second region 110y, and is characterized in that the upper surface of the second region 110y is higher than the upper surface of the first region 110x. The light-emitting layer 115 includes a light-emitting layer 115r, a light-emitting layer 115g, and a light-emitting layer 115b. For example, the light-emitting layer 115r can correspond to the light-emitting layer of a red light-emitting element, the light-emitting layer 115g to the light-emitting layer of a green light-emitting element, and the light-emitting layer 115b to the light-emitting layer of a blue light-emitting element.

[0045] <Insulated film 101> As shown in Figure 1, an insulating film 101 is provided on the transistor described above. This insulating film becomes the surface to be formed on for the anode and other components that are later formed. Therefore, it is preferable to form the insulating film 101 using an organic material so that the surface to be formed on is flat. Furthermore, it is preferable to form the insulating film 101 using an inorganic material so that it functions as a protective film to prevent impurities from entering the transistor. For the insulating film 101 to have flatness and function as a protective film, it is preferable to have a laminated structure having at least a first insulating film made of an inorganic material and a second insulating film made of an organic material located on the first insulating film.

[0046] The insulating film 101 may be formed using an organic resin such as polyimide resin, polyamide resin, acrylic resin, siloxane resin, silicone resin, epoxy resin, or phenolic resin. Alternatively, materials to which impurity elements such as lanthanum (La), nitrogen, or zirconium (Zr) have been added may be used.

[0047] The insulating film 101 may be formed by including one or more inorganic materials such as aluminum oxide, magnesium oxide, silicon oxide, silicon oxide nitride, silicon oxide nitride, silicon nitride, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, and tantalum oxide. Alternatively, materials may be used in which impurity elements such as lanthanum (La), nitrogen, and zirconium (Zr) are added to the above materials.

[0048] <Anode 102> An anode 102 is formed on the insulating film 101. The anode 102 is electrically connected to the transistor via a contact hole or the like provided in the insulating film 101. A contact hole is an opening formed in the insulating film that allows a wiring layer located below the insulating film (referred to as the lower wiring layer) to be electrically connected to a wiring layer located above the insulating film (referred to as the upper wiring layer). To enable electrical connection, the lower wiring layer has a region exposed through the opening, and the upper wiring layer has a region located within the opening in a cross-sectional view.

[0049] The anode 102 is supplied with a signal, such as a predetermined potential, by the transistor mentioned above. Therefore, the anode 102 is processed to be independent for each subpixel. This process of independent processing is sometimes referred to as "separation." Furthermore, this processing is sometimes referred to as "patterning." Additionally, the anode 102 electrically connected to the transistor is sometimes referred to as the pixel electrode.

[0050] It is desirable to use a material with a high work function for the anode 102. For example, the anode 102 may be an ITO film (a film containing indium, tin, and oxygen, referred to as an indium tin oxide film), an indium tin oxide film containing silicon, an indium oxide film containing 2-20 wt% zinc oxide, or a titanium nitride film. Alternatively, the anode 102 may have a single layer film such as a chromium film, tungsten film, Zn film, Al film, Ag film, or Pt film. Furthermore, the anode 102 can use a multilayer structure, for example, a multilayer structure of a titanium nitride film and a film mainly composed of aluminum, or a three-layer multilayer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film. The multilayer structure has the effect of allowing the anode to function while lowering the resistance as a wiring, and furthermore, achieving good ohmic contact with other layers. The overall film thickness of the anode 102 is preferably between 100 nm and 250 nm.

[0051] In the case of a display device that extracts light from a light-emitting element from the anode 102 side, the anode 102 has a transparent electrode with light transmission. The transparent electrode is made of a material that is light-transmitting, or if a non-light-transmitting material is used, it is made into a thin film. The light transmittance of the transparent electrode should be 40% or more. That is, it is preferable to use a transparent electrode for the anode 102 that has a transmittance of 40% or more for visible light (light with a wavelength of 400 nm or more and less than 750 nm).

[0052] The top surface shape of the anode 102 is not limited, but Figure 1 shows a rectangular shape, with the shorter side of the rectangle aligned with the X direction and the longer side aligned with the Y direction.

[0053] Figures 2A and 2B show cross-sectional views of the pixel region 100 shown in Figure 1 along the dashed line AB. The cross-sectional shape of the anode 102 is not limited, but Figures 2A and 2B show the case where the end of the anode 102 has a tapered shape.

[0054] Furthermore, Figures 3A to 3C show cross-sectional views of the pixel region 100 shown in Figure 1 along the dashed line CD. In Figures 3A to 3C, the ends of the anode 102 also have a tapered shape.

[0055] In addition, while Figures 2A to 3C show a tapered shape at the end of the anode 102 where the upper edge is shorter than the lower edge, an inverse tapered shape where the lower edge is shorter than the upper edge may also be applied. Of course, the end of the anode 102 does not have to be tapered; it may have a straight shape where the upper and lower edges are roughly the same length (a shape where the end is vertical in cross-sectional view, or a shape where the end is roughly vertical).

[0056] The tapered shape described above includes a region where the anode 102 gradually becomes thinner. This tapered shape helps to suppress cutting of the thin film formed on the anode 102.

[0057] The anode having the thinned-film region described above may have gradually increasing resistance. In other words, anode 102 contains a region of high resistance corresponding to its tapered shape. This region of the anode with high resistance can also be considered a region where the signal supplied from the transistor, specifically the voltage, is difficult to apply.

[0058] <Hole injection layer 104> As shown in Figures 1 to 3C, a hole injection layer 104 is formed on the anode 102. Since the hole injection layer 104 is formed on the anode 102, it is preferable because it is less likely to be cut. The hole injection layer 104 is not divided by each subpixel like the anode 102, but is formed over the entire pixel region 100. That is, the hole injection layer 104 is formed across multiple anodes and can be common to each subpixel. A layer that can be common to each subpixel is referred to as a common layer. The hole injection layer 104 can be formed by a wet method or a vapor deposition method, and by making the hole injection layer 104 a common layer, the process of coating each subpixel separately becomes unnecessary.

[0059] The hole injection layer 104 has a region that overlaps with the tapered region of the anode 102. As described above, the tapered region of the anode 102 has high resistance, so in the portion that overlaps with this high-resistance region, holes are less likely to be injected from the anode 102 into the hole injection layer 104, or no holes are injected at all. Having the above portion of the hole injection layer 104 makes it possible to suppress crosstalk between adjacent light-emitting elements. Crosstalk is the transmission of signals from the transistors of adjacent sub-pixels to sub-pixels that are not being driven. Suppression of crosstalk is particularly desirable when adjacent light-emitting elements are of different colors.

[0060] When a hole injection layer 104 is formed on the anode 102 having the above-described reverse tapered shape and sharp edge shape, the hole injection layer 104 is cut, and therefore the above-described crosstalk is suppressed.

[0061] One of the benefits of this configuration, in which the hole injection layer 104 and the like are provided along the anode 102, is the suppression of crosstalk.

[0062] As will be described later, a hole transport layer may be provided on the hole injection layer 104.

[0063] <Bulkhead 110> In this embodiment, since the light-emitting layer is applied using a wet method, such as an inkjet method, a section for dropping the solution is necessary. This section can be provided by an insulating material, and such an insulating material may be referred to as a partition wall, embankment, or bank.

[0064] In Figures 1 to 3C, partitions 110 are formed on the hole injection layer 104, and these partitions 110 are used to demarcate subpixels, i.e., light-emitting regions. The partitions 110 that demarcate each subpixel form a grid shape in a top view of the pixel region 100, as shown in Figure 1. In a cross-sectional view of the pixel region 100, as shown in Figures 2A to 3C, the partitions 110 have openings 112 corresponding to the subpixels, i.e., light-emitting regions. In a top view, the hole injection layer 104 is exposed through the openings 112, and a solution containing a starting material such as the light-emitting layer 115r can be dropped so as to overlap with at least the exposed hole injection layer 104.

[0065] Before dropping the solution containing the starting material such as the light-emitting layer 115r, a solution X containing the starting material for the hole transport layer may be dropped. After dropping the solution X, the solvent can be removed from the solution X through a firing process or the like, and then cured to obtain the hole transport layer.

[0066] Furthermore, Figure 2A shows that the upper end of the second region 110y has a corner, and Figure 2B shows that the upper end of the second region 110y has a rounded portion. Figure 3A shows that the upper end of the first region 110x has a corner, and Figure 3B shows that the upper end of the first region 110x has a rounded portion. Moreover, Figure 3C shows that the upper end of the first region 110x has a rounded portion, and the light-emitting layer 115r is also provided on the upper surface of the first region 110x. The light-emitting material of the light-emitting layer 115r, that is, the light-emitting material of the starting material, will be described later.

[0067] As shown in Figures 2A to 3C, in the cross-sectional view of the pixel region 100, the end of the partition wall 110 is preferably tapered. For example, the lower end of the partition wall 110 can be made longer than the upper end to provide a tapered shape. Furthermore, the partition wall 110 can also have an inverse tapered shape, where the lower end is shorter than the upper end. By providing a tapered shape at the end of the partition wall 110, the solution from the inkjet device is dropped into the area of ​​the target light-emitting element, making it less likely for the solutions to mix between adjacent light-emitting elements of different colors.

[0068] The above-mentioned tapered shape includes a shape in which the partition wall 110 has a region in which it gradually becomes thinner. The thin film formed on the partition wall 110 having the above-mentioned tapered shape can be suppressed from cutting, etc.

[0069] The tapered shape of the end of the partition wall 110 can be as shown in Figures 2A to 3C, where the upper edge is shorter than the lower edge. However, the end of the partition wall 110 can also be a reverse tapered shape, where the lower edge is shorter than the upper edge. Of course, the end of the partition wall 110 may not be tapered, but may have a straight shape where the upper and lower edges are roughly the same length (a shape where the end is vertical in cross-sectional view, or a shape where the end is roughly vertical).

[0070] The partition wall 110 has a single-layer or multi-layer structure of inorganic material, a single-layer or multi-layer structure of organic material, or a multi-layer structure of inorganic and organic material. In the case of a multi-layer structure of inorganic and organic material, one of the inorganic or organic material is located in the lower layer and the other in the upper layer.

[0071] The partition wall 110 may be formed using one or more inorganic materials including aluminum oxide, magnesium oxide, silicon oxide, silicon oxide nitride, silicon oxide nitride, silicon nitride, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, and tantalum oxide. Alternatively, materials with impurity elements such as lanthanum (La), nitrogen, and zirconium (Zr) added to the above materials may be used. The partition wall 110 formed from the inorganic material may have corners at its upper end, as shown in Figures 2A and 3A.

[0072] The partition wall 110 may be formed using an organic resin such as polyimide resin, polyamide resin, acrylic resin, siloxane resin, silicone resin, epoxy resin, or phenolic resin. Alternatively, materials to which impurity elements such as lanthanum (La), nitrogen, or zirconium (Zr) have been added may be used. The partition wall 110 formed from the organic material has a rounded portion at its upper end, as shown in Figures 2B, 3B, and 3C. Having a rounded portion is sometimes described as the upper end having curvature or being rounded.

[0073] The lower end of the partition wall 110 should also be rounded. Although not shown in the diagram, if a negative-type or positive-type photosensitive resin is used as the organic material, the upper and lower ends of the partition wall 110 can be rounded.

[0074] <Height of partition wall 110> The partition wall 110 has a first region 110x extending along the X direction and a second region 110y extending along the Y direction. In a cross-sectional view of the pixel region 100, the first region 110x and the second region 110y have different heights.

[0075] Figures 1 to 3C show the case where the uppermost surface of the partition wall 110 is higher in the second region 110y than in the first region 110x. In this embodiment, since the uppermost surface positions of the partition wall 110 are being compared, the film thickness of the first region 110x and the film thickness of the second region 110y may be larger. Also, as shown in Figure 1, the highest point of the uppermost surface of the partition wall 110 is the intersection of the first region 110x and the second region 110y.

[0076] The configuration in which the partition wall 110 has different heights in the first region 110x and the second region 110y is suitable for an inkjet method where the partition wall 110 is the surface to be formed. Figure 4 shows how the light-emitting layer is applied by inkjet, and it is preferable that the nozzles 119r, 119g, and 119b of the inkjet device be moved along the second region 110y, where the uppermost surface is higher.

[0077] Figure 4 shows nozzles 119r, 119g, and 119b, illustrating how solutions containing different light-emitting layer starting materials are dropped from each nozzle. However, solutions containing the same light-emitting layer starting material may also be dropped from the nozzles. In this case, light-emitting elements of the same color can be formed along the second region 110y, which is considered to be highly productive for mass production.

[0078] Figure 4 shows a partition wall 110 corresponding to Figure 2A, which has a corner at the upper end and a tapered end. However, the partition wall 110 may also have a rounded upper end and a tapered end as shown in Figure 2B, or it may have any other shape.

[0079] It is preferable to move the inkjet device along the partition wall 110 in the region where the uppermost surface is located. That is, the uppermost surface of the first region 110x of the partition wall may be made higher than the uppermost surface of the second region 110y of the partition wall, and the inkjet device may be moved along the first region 110x.

[0080] As shown in Figure 1, the second region 110y is positioned between different colored light-emitting elements. That is, the second region 110y is positioned between subpixels where different colored light-emitting elements are formed. This arrangement of the second region 110y also has the effect of preventing the solution ejected from the nozzle from mixing colors between the subpixels.

[0081] Even without the first region 110x, it is possible to prevent color mixing, but the solution begins to dry and aggregate the moment it is dropped, and it is difficult to control this aggregation. To prevent the above aggregation, it is preferable that the first region 110x be placed for each sub-pixel. In other words, in order to prevent the above color mixing, it is preferable that the first region 110x be placed in addition to the second region 110y, so that the solution discharged from the nozzle can remain in the desired light-emitting region.

[0082] <Method 1 for fabricating the first region 110x and the second region 110y> The method for fabricating the first region 110x and the second region 110y shown in Figure 1 will now be explained. First, only the second region 110y is formed in a strip shape. The second region 110y can be formed by selecting a material from the partition wall 110. For example, photosensitive polyimide will be used. A polyimide precursor is applied to the entire pixel region 100 and dried. A mask is placed using a photoresist or the like so as to overlap with the region to be the second region 110y. Alternatively, the mask can be placed so as to overlap with the region other than the second region 110y. When exposure and development are performed using this mask, polyimide is placed corresponding to the second region 110y. After that, imidization is performed as needed. In this way, the second region 110y can be obtained.

[0083] Next, the first region 110x is formed in a strip shape using the same material as the second region 110y. Specifically, the first region 110x can be obtained by following the same process as the process for the second region 110y described above.

[0084] Since both the second region 110y and the first region 110x are formed in a strip shape, mask placement is easy. To increase the height of the second region 110y, the amount of precursor used when forming the second region 110y is greater than when forming the first region 110x in a strip shape. The second region 110y should have a height of 1.5 to 3 times that of the first region 110x. Also, since the polyimides of both regions are stacked at their intersection, the top surface will be the highest. To control the height of the intersection, the position of the mask used when forming the first region 110x is changed so that the polyimide corresponding to the first region 110x is not formed at that intersection.

[0085] In this way, the first region 110x and the second region 110y, as shown in Figure 1, can be obtained.

[0086] <Method 2 for fabricating the first region 110x and the second region 110y> The method for fabricating the first region 110x and the second region 110y shown in Figure 1 will now be explained. As mentioned before, the partition wall 110 can be a laminated structure such as a lower partition wall made of inorganic material and an upper partition wall made of organic material. For example, an inorganic material that will become the lower partition wall is first deposited over the entire pixel region 100, and then an organic material that will become the upper partition wall is formed on top of it. This laminated structure is then applied to the second region 110y. Then, either only the inorganic material or only the organic material is applied to the first region 110x. In this way, the first region 110x and the second region 110y can also be obtained.

[0087] Furthermore, the upper partition can be used as a mask for processing the lower partition. Therefore, in a cross-sectional view, the end of the upper partition and the end of the lower partition can coincide or roughly coincide. Alternatively, the end of the upper partition can be located inside the end of the lower partition, which is made of inorganic material.

[0088] Furthermore, if the upper partition is not used as a mask for processing the lower partition, the end of the upper partition can be located outside the end of the lower partition, which is made of inorganic material.

[0089] <Emitting layer 115r, 115g, 115b> After forming the partition wall 110, light-emitting layers 115r, 115g, and 115b are formed on the hole injection layer 104 by applying them in separate layers, as shown in Figures 1 to 4. This separated layer structure corresponds to the light-emitting element of the SBS structure. The light-emitting colors of the light-emitting layers 115r, 115g, and 115b correspond to red, green, and blue, which are representative of full-color display.

[0090] As mentioned before, the light-emitting layer 115r may be formed on the first region 110x, as shown in Figure 3C. When the solution is continuously discharged from the nozzle, the light-emitting layer 115r is more likely to be formed on the first region 110x. The same applies to the light-emitting layer 115g and the light-emitting layer 115b.

[0091] To reiterate, wet processes include spin coating, inkjet, casting, printing, dispensing, and spraying. Productivity can be improved by forming at least the light-emitting layer using a wet process. If the display device is flexible, a configuration in which at least the light-emitting layer is formed using a wet process is highly flexible and therefore preferable.

[0092] Examples of solvents used in the wet process include chlorine-based solvents such as dichloroethane, trichloroethane, chlorobenzene, and dichlorobenzene; ether-based solvents such as tetrahydrofuran, dioxane, anisole, and methylanisole; aromatic hydrocarbon solvents such as toluene, xylene, mesitylene, ethylbenzene, hexylbenzene, and cyclohexylbenzene; aliphatic hydrocarbon solvents such as cyclohexane, methylcyclohexane, pentane, hexane, heptane, octane, nonane, decane, dodecane, and bicyclohexyl; ketone-based solvents such as acetone, methyl ethyl ketone, benzophenone, and acetophenone; ester-based solvents such as ethyl acetate, butyl acetate, ethyl cellosolve acetate, methyl benzoate, and phenyl acetate; polyhydric alcohol-based solvents such as ethylene glycol, glycerin, and hexanediol; alcohol-based solvents such as isopropyl alcohol and cyclohexanol; sulfoxide-based solvents such as dimethyl sulfoxide; and amide-based solvents such as methylpyrrolidone and dimethylformamide. Furthermore, one or more solvents can be used.

[0093] The starting material for the light-emitting layer formed by the inkjet method is preferably a polymer material (sometimes referred to as a polymer-based light-emitting organic material). In other words, it is preferable to use a polymer material that is easily miscible with the above-mentioned solvent in order to obtain the solution dropped by the inkjet method.

[0094] <About inkjet printers> As shown in Figure 4, the inkjet device has nozzles 119r, 119g, and 119b. Nozzle 119 includes nozzles 119r, 119g, and 119b, and the diameter of the opening (also called the nozzle diameter) from which the solution is ejected is between several μm and several tens of μm. The part containing the nozzles is sometimes called the head. The head is equipped with a solution ejection control unit to dispense the solution, which may include a piezoelectric element (piezo element), for example. This pressure element can change the volume of the ink tank connected to the nozzle, thereby dispensing the solution. The amount of one drop is often between several pl and several tens of pl, depending on the nozzle diameter. One pl of solution can be considered as the amount that forms a cube with sides of about 10 μm.

[0095] The solution may be dispensed intermittently dropwise from nozzles 119r, 119g, and 119b. When dispensed intermittently, the solution may be referred to as a droplet. Alternatively, the solution may be dispensed continuously in a linear fashion from nozzles 119r, 119g, and 119b. In both intermittent and continuous dispensing cases, the solution may be coated onto the partition wall 110.

[0096] When the light-emitting layers 115r, 115g, and 115b are formed using a wet method or the like, liquid reservoirs form near the partition wall 110, as shown in Figures 2A to 3C. Figures 2A to 3C show the first liquid reservoir 118r, the second liquid reservoir 118g, and the third liquid reservoir 118b, corresponding to the light-emitting layers 115r, 115g, and 115b, respectively. Each liquid reservoir can be seen in the area enclosed by the dotted circle.

[0097] Liquid accumulation occurs as a result of the drying process performed in an atmospheric or reduced-pressure atmosphere to remove the solvent from the solution discharged by the wet process. In particular, during the drying process in a reduced-pressure atmosphere, liquid accumulation occurs due to the phenomenon of solute gathering outward, driven by the surface tension of the solution. Liquid accumulation can be described as the area around the inside of the partition wall 110 (for example, the area marked with a dotted circle in Figures 2A to 3B) where the luminescent layer is thicker than in the center. Because this liquid accumulation causes current to concentrate in the center of the luminescent area, resulting in uneven current density, it is desirable to minimize the size of the liquid accumulation area.

[0098] In one aspect of the present invention, since the partition wall 110 is formed on the hole injection layer 104, there is no liquid accumulation in the hole injection layer 104 even when the hole injection layer 104 is formed by a wet method. That is, in one aspect of the present invention, there is a minute liquid accumulation corresponding to the light-emitting layer formed by the wet method. With this aspect of the present invention, it is possible to provide a display device having a small liquid accumulation area and a high-resolution pixel area 100.

[0099] Figure 5 shows a partition 110 that differs from the pixel region 100 shown in Figure 1 in that the first region 110x is higher than the second region 110y. The second region 110y has a height that allows a solution to be dropped into the same-colored light-emitting layer area and prevents color mixing, while the first region 110x is higher than that. In Figure 5, even among same-colored light-emitting layers, the first region 110x provides sufficient separation. Therefore, crosstalk between adjacent light-emitting elements can be prevented among same-colored light-emitting layers.

[0100] To reiterate, a hole transport layer may be provided between the hole injection layer 104 and the light-emitting layer 115.

[0101] After the light-emitting layer 115 is formed, an electron transport layer, an electron injection layer, and a cathode are provided to complete the light-emitting element. The electron transport layer, electron injection layer, and cathode can be formed over the entire pixel region 100. In other words, the electron transport layer, electron injection layer, or cathode that is common to each pixel is a common layer. The electron transport layer, electron injection layer, and cathode can be formed by a wet method or a vapor deposition method. When forming a common layer, the spin coating method is preferable as the wet method.

[0102] <Configuration Example 2> Unlike the above-described configuration example 1, configuration example 2, in which a hole transport layer 105 is formed on the hole injection layer 104, will be described. Figure 6 shows a perspective view example of a display device, Figures 7A to 8C show cross-sectional views of a display device, Figure 9 shows an example of a light-emitting layer fabrication, and Figure 10 shows a perspective view example of a display device different from Figure 6.

[0103] As shown in Figure 6, the display device has a pixel region 100 and other areas such as a drive circuit region. The pixel region 100 in Figure 6 shows an insulating film 101, an anode 102, a hole injection layer 104, a hole transport layer 105, a partition wall 110, a light-emitting layer 115, etc. The partition wall 110 includes a first region 110x and a second region 110y, and is characterized in that the upper surface of the second region 110y is higher than the upper surface of the first region 110x. The light-emitting layer 115 includes a light-emitting layer 115r, a light-emitting layer 115g, and a light-emitting layer 115b. For example, the light-emitting layer 115r can correspond to the light-emitting layer of a red light-emitting element, the light-emitting layer 115g to the light-emitting layer of a green light-emitting element, and the light-emitting layer 115b to the light-emitting layer of a blue light-emitting element. The configuration of the pixel region 100 has some parts that are the same as in Configuration Example 1, and in the cases where they are the same, the explanation is omitted.

[0104] <Insulated film 101> As shown in Figure 6, an insulating film 101 is provided on the transistor described above. The insulating film can have the same configuration as <insulating film 101> in Configuration Example 1, and the configuration and other details are as described in <insulating film 101> of Configuration Example 1. Therefore, a detailed explanation of the insulating film 101 is omitted in Configuration Example 2.

[0105] <Anode 102> The insulating film 101 has an anode 102. The anode can have the same configuration as the anode 102 in Configuration Example 1, and the configuration is as described in the anode 102 section of Configuration Example 1. Therefore, a detailed explanation of the anode 102 is omitted in Configuration Example 2.

[0106] Figures 7A and 7B show cross-sectional views of the pixel region 100 shown in Figure 6 along the dashed line AB. The cross-sectional shape of the anode 102 is not limited, but Figures 7A and 7B show the case where the end of the anode 102 has a tapered shape.

[0107] Furthermore, Figures 8A to 8C show cross-sectional views of the pixel region 100 shown in Figure 6 along the dashed line CD. In Figures 8A to 8C, the ends of the anode 102 also have a tapered shape.

[0108] In addition, while Figures 7A to 8C show a tapered shape at the end of the anode 102 where the upper edge is shorter than the lower edge, an inverse tapered shape where the lower edge is shorter than the upper edge may also be applied. Of course, the end of the anode 102 does not have to be tapered; it may have a straight shape where the upper and lower edges are roughly the same length (a shape where the end is vertical in cross-sectional view, or a shape where the end is roughly vertical).

[0109] The tapered shape described above can suppress the cutting of the thin film formed on the anode 102.

[0110] The anode having the thinned-film region described above may have gradually increasing resistance. In other words, anode 102 contains a region of high resistance corresponding to its tapered shape. This region of the anode with high resistance can also be considered a region where the signal supplied from the transistor, specifically the voltage, is difficult to apply.

[0111] <Hole injection layer 104> As shown in Figures 6 to 8C, a hole injection layer 104 is formed on the anode 102. The hole injection layer can have the same configuration as the <hole injection layer 104> in Configuration Example 1, and the configuration is as described in <hole injection layer 104> of Configuration Example 1. Therefore, a detailed explanation of the hole injection layer 104 is omitted in Configuration Example 2.

[0112] <Hole transport layer 105> As shown in Figures 6 to 8C, in Configuration Example 2, a hole transport layer 105 is formed on the hole injection layer 104. The hole transport layer 105 is formed over the entire pixel region 100, without being divided by each pixel like the anode 102. That is, the hole transport layer 105 is formed across multiple anodes and can be common to each pixel. To reiterate, a layer that can be common to each sub-pixel is referred to as a common layer. The hole transport layer 105 can be formed by a wet method or a vapor deposition method, and by making the hole transport layer 105 a common layer, the process of coating each sub-pixel separately becomes unnecessary.

[0113] The hole transport layer 105 has a region that overlaps with the tapered region of the anode 102. As described above, the tapered region of the anode 102 has high resistance, so the hole transport layer 105 has difficulty transporting holes, or is unable to transport holes, in the portion that overlaps with this high-resistance region. By having the above region in the hole transport layer 105, crosstalk between adjacent light-emitting elements of different colors can be suppressed.

[0114] As described in Configuration Example 1, in the region overlapping with the high-resistance region, the hole injection layer 104 is less likely to receive holes from the anode 102, or no holes are injected at all. By providing such a hole injection layer 104 together with the hole transport layer 105, crosstalk between adjacent light-emitting elements of different colors can be further suppressed.

[0115] When a hole transport layer 105 is formed on the anode 102 having the above-described inverse tapered shape and sharp-edged shape, the crosstalk is suppressed by the cutting of the hole transport layer 105.

[0116] One of the benefits of this configuration, in which the hole transport layer 105 and the like are arranged along the anode 102, is the suppression of crosstalk.

[0117] <Bulkhead 110> In this embodiment, since the light-emitting layer is applied using a wet method, such as an inkjet method, a section for dropping the solution is necessary. This section can be provided by an insulating material, and such an insulating material may be referred to as a partition wall, embankment, or bank.

[0118] In Figures 6 to 8C, partitions 110 are formed on the hole transport layer 105, and these partitions 110 are used to demarcate subpixels, i.e., light-emitting regions. The partitions 110 can have the same configuration as <partition 110> in Configuration Example 1, and the configuration and other details are as described in <partition 110> of Configuration Example 1. Therefore, a detailed explanation of partitions 110 is omitted in Configuration Example 2.

[0119] <Height of partition wall 110> The partition wall 110 has a first region 110x extending along the X direction and a second region 110y extending along the Y direction. In a cross-sectional view of the pixel region 100, the first region 110x and the second region 110y have different heights.

[0120] Figures 6 to 8C show the case where the uppermost surface of the partition wall 110 is higher in the second region 110y than in the first region 110x. In this embodiment, since the uppermost surface positions of the partition wall 110 are being compared, the film thickness of the first region 110x and the film thickness of the second region 110y can be larger or smaller. Also, as shown in Figure 6, the highest point of the uppermost surface of the partition wall 110 is the intersection of the first region 110x and the second region 110y.

[0121] The configuration in which the partition wall 110 has different heights in the first region 110x and the second region 110y is suitable for an inkjet method where the partition wall 110 is the surface to be formed. Figure 9 shows how the light-emitting layer is coated with a solution using an inkjet method, and it is preferable that the nozzles 119r, 119g, and 119b of the inkjet device be moved along the second region 110y, where the uppermost surface is located higher.

[0122] Figure 9 shows nozzles 119r, 119g, and 119b, illustrating how solutions containing different light-emitting layer starting materials are dropped from each nozzle. However, solutions containing the same light-emitting layer starting material may also be dropped from the nozzles. In this case, light-emitting elements of the same color can be formed along the second region 110y, which is considered to be highly productive for mass production.

[0123] Figure 9 shows a partition wall 110 corresponding to Figure 7A, which has a corner at the upper end and a tapered end. However, the partition wall 110 may also have a rounded upper end and a tapered end, as shown in Figure 7B, or it may have any other shape. In Figure 9, the inkjet device can be moved along the partition wall 110 in the area where the uppermost surface is located.

[0124] It is preferable to move the inkjet device along the partition wall 110 in the region where the uppermost surface is located. That is, the uppermost surface of the first region 110x of the partition wall may be made higher than the uppermost surface of the second region 110y of the partition wall, and the inkjet device may be moved along the first region 110x.

[0125] As shown in Figure 6, the second region 110y is positioned between light-emitting elements of different colors. In other words, the second region 110y is positioned between sub-pixels corresponding to light-emitting elements of different colors. This arrangement of the second region 110y also has the effect of preventing the solution dispensed from the nozzle from mixing colors between the sub-pixels.

[0126] Even without the first region 110x, it is possible to prevent color mixing, but the solution begins to dry and aggregate the moment it is dropped, and it is difficult to control this aggregation. To prevent the above aggregation, it is preferable that the first region 110x be placed for each sub-pixel. In other words, in order to prevent the above color mixing, it is preferable that the first region 110x be placed in addition to the second region 110y, so that the solution discharged from the nozzle can remain in the desired light-emitting region.

[0127] <Method 3 for fabricating the first region 110x and the second region 110y> The method for fabricating the first region 110x and the second region 110y shown in Figure 6 can be the same as the method for fabricating the first region 110x and the second region 110y 1 and the method for fabricating the first region 110x and the second region 110y 2 in Configuration Example 1, and a detailed explanation of this method will be omitted.

[0128] <Emitting layer 115r, 115g, 115b> After forming the partition wall 110, light-emitting layers 115r, 115g, and 115b are formed on the hole transport layer 105 by applying them in separate layers, as shown in Figures 6 to 9. This separated layered structure corresponds to the light-emitting element of the SBS structure. The light-emitting colors of the light-emitting layers 115r, 115g, and 115b correspond to red, green, and blue, which are representative of full-color display.

[0129] The light-emitting layers 115r, 115g, and 115b are formed by a wet process. The wet process and other related methods can be the same as those described in the specific methods and materials for <light-emitting layers 115r, 115g, and 115b> of Configuration Example 1, and these methods and configurations are as described in the <light-emitting layers 115r, 115g, and 115b> of Configuration Example 1. Therefore, a detailed explanation is omitted in Configuration Example 2.

[0130] As shown again in Figure 8C, the light-emitting layer 115r may be formed on the first region 110x. When the solution is continuously discharged from the nozzle, the light-emitting layer 115r is more likely to be formed on the first region 110x. The same applies to the light-emitting layer 115g and the light-emitting layer 115b.

[0131] <About inkjet printers> As shown in Figure 9, the inkjet device has nozzles 119r, 119g, and 119b. The inkjet device and the like can have the same configuration as described in the section "About the Inkjet Device" in Configuration Example 1, and are as described in the section "About the Inkjet Device" in Configuration Example 1. Therefore, the detailed explanation of "About the Inkjet Device" is omitted in Configuration Example 2.

[0132] When the light-emitting layers 115r, 115g, and 115b are formed using a wet method or the like, liquid reservoirs form near the partition wall 110, as shown in Figures 7A to 8C. In Figures 7A to 8C, the first liquid reservoir 118r, the second liquid reservoir 118g, and the third liquid reservoir 118b are shown, corresponding to the light-emitting layers 115r, 115g, and 115b, respectively.

[0133] Liquid accumulation occurs as a result of the drying process performed in an atmospheric or reduced-pressure atmosphere to remove the solvent from the solution discharged by the wet process. In particular, during the drying process in a reduced-pressure atmosphere, liquid accumulation occurs due to the phenomenon of solute gathering outward, driven by the surface tension of the solution. Liquid accumulation can be described as the area around the inside of the partition wall 110 (for example, the area marked with a dotted circle in Figures 7A to 8B) where the luminescent layer is thicker than in the center. Because this liquid accumulation causes current to concentrate in the center of the luminescent area, resulting in uneven current density, it is desirable for the liquid accumulation area to be as small as possible.

[0134] In one aspect of the present invention, since the partition wall 110 is formed on the hole transport layer 105, there is no liquid accumulation in the hole transport layer even when the hole transport layer 105 is formed by a wet process. That is, in one aspect of the present invention, there is a minute liquid accumulation corresponding to the light-emitting layer formed by the wet process. With this aspect of the present invention, it is possible to provide a display device having a small liquid accumulation area and a high-resolution pixel area 100.

[0135] Figure 10 shows a partition wall 110 that differs from the partition wall 110 shown in Figure 6 in that the first region 110x is higher than the second region 110y. The second region 110y has a height that allows a solution to be dropped into the same-colored light-emitting layer area and prevents color mixing, while the first region 110x is higher than that. In Figure 10, even among same-colored light-emitting layers, the first region 110x provides sufficient separation. Therefore, crosstalk between adjacent pixels in same-colored light-emitting layers can be prevented.

[0136] After the light-emitting layer 115 is formed, the electron transport layer, electron injection layer, and cathode are added to complete the light-emitting element. The electron transport layer, electron injection layer, and cathode can be formed over the entire pixel region 100. In other words, the electron transport layer, electron injection layer, and cathode are common layers in each pixel. The electron transport layer, electron injection layer, and cathode can be formed by a wet method or a vapor deposition method. When forming a common layer, the spin coating method is preferable as the wet method.

[0137] The details described in this embodiment can be used in combination with other embodiments.

[0138] (Embodiment 2) This embodiment describes a light-emitting element that can be used in a display device according to one aspect of the present invention.

[0139] <Example of light-emitting element configuration> As shown in Figure 11A, the light-emitting element 20 has a light-emitting unit 686 between a pair of electrodes (lower electrode 672, upper electrode 688). The light-emitting unit 686 has a plurality of functional layers, such as layer 4430, light-emitting layer 4421, and layer 4420, starting from the lower electrode 672. In one aspect of the present invention, a partition wall 110 is positioned relative to a functional layer formed by a wet process. For example, when the light-emitting layer 4421 is formed by a wet process, a partition wall 110 is provided on layer 4430 for the partition of the light-emitting layer 4421. Although not shown, the partition wall 110 has a first region and a second region of different heights as described in the above embodiment.

[0140] The light-emitting layer 4421 may be, for example, a functional layer having a light-emitting material.

[0141] Layers 4420 and 4430 will now be described. For example, as in the embodiment described above, when the lower electrode 672 is the anode and the upper electrode 688 is the cathode, the layer 4430 located on the lower electrode 672 may be a structure in which a hole injection layer and a hole transport layer, etc., are stacked in order from the lower electrode. Note that layer 4430 may be either a hole injection layer or a hole transport layer. Similarly, the layer 4420 may be a structure in which an electron injection layer and an electron transport layer, etc., are stacked in order from the upper electrode. Note that layer 4420 may be either an electron injection layer or an electron transport layer.

[0142] Furthermore, although different from the above embodiment, the lower electrode 672 can be used as the cathode and the upper electrode 688 as the anode. In this case, the layer 4430 located on the lower electrode 672 may use a structure in which an electron injection layer and an electron transport layer, etc., are stacked in order from the lower electrode. Layer 4430 may also be either an electron injection layer or an electron transport layer. Also, the layer 4420 may use a structure in which a hole injection layer and a hole transport layer, etc., are stacked in order from the upper electrode. Layer 4430 may also be either a hole injection layer or a hole transport layer.

[0143] The lower electrode 672 can be formed by vapor deposition, CVD, or sputtering. The upper electrode 688 can also be formed by vapor deposition, CVD, or sputtering. Layer 4430 can be formed by a wet process or vapor deposition. Layer 4420 can also be formed by a wet process or vapor deposition.

[0144] In Figure 11A, a partition wall 110 is formed on layer 4430, and a light-emitting layer 4421 is formed on layer 4430 exposed from the partition wall 110 in a top view using a wet method such as inkjet. Layer 4420 and the upper electrode 688 can be a common layer, and it is preferable that layer 4420 and the upper electrode 688 are formed over the partition wall 110 as shown in Figure 11A. It is preferable to make the common layer thicker so that it can over the partition wall 110. If there are constraints on making the common layer thicker, the light-emitting layer 4421 may be made thicker. In this case, for example, the amount of solution dropped from the inkjet device should be adjusted so that the film thickness of the light-emitting layer is 2 / 3 times or more but less than 1 of the height of the partition wall 110.

[0145] Next, Figure 11B shows a more detailed configuration of Figure 11A. The light-emitting element 20 shown in Figure 11B has a layer 4430-1 on the lower electrode 672, a layer 4430-2 on layer 4430-1, a light-emitting layer 4421 on layer 4430-2, a layer 4420-1 on the light-emitting layer 4421, a layer 4420-2 on layer 4420-1, and an upper electrode 688 on layer 4420-2, with partition walls 110 positioned relative to the layers formed by the wet method. For example, when the light-emitting layer 4421 is formed by the wet method, partition walls 110 are provided on layer 4430-2 for the partition of the light-emitting layer 4421. Although not shown, the partition walls 110 have a first region and a second region of different heights as described in the above embodiment.

[0146] For example, as in the embodiment described above, when the lower electrode 672 is used as the anode and the upper electrode 688 is used as the cathode, layer 4430-1 functions as a hole injection layer, layer 4430-2 functions as a hole transport layer, layer 4420-1 functions as an electron transport layer, and layer 4420-2 functions as an electron injection layer.

[0147] In addition, although different from the above embodiment, the lower electrode 672 can be used as the cathode and the upper electrode 688 as the anode. In this case, layer 4430-1 functions as an electron injection layer, layer 4430-2 functions as an electron transport layer, layer 4420-1 functions as a hole transport layer, and layer 4420-2 functions as a hole injection layer.

[0148] This layered structure allows for efficient injection of carriers (holes and electrons) into the light-emitting layer 4421, thereby increasing the efficiency of carrier recombination within the light-emitting layer 4421. The layers between the light-emitting layer 4421 and the lower electrode 672, and between the light-emitting layer 4421 and the upper electrode 688, are not limited to these, and may include carrier blocking layers, exciton blocking layers, etc., as appropriate. Furthermore, layers possessing both carrier transport and carrier injection functions may be used.

[0149] The lower electrode 672 can be formed by vapor deposition, CVD, or sputtering. The upper electrode 688 can also be formed by vapor deposition, CVD, or sputtering. Layer 4430-1 can be formed by a wet process or vapor deposition. Layer 4430-2 can also be formed by a wet process or vapor deposition. Layer 4420-1 can also be formed by a wet process or vapor deposition. Layer 4420-2 can also be formed by a wet process or vapor deposition.

[0150] In Figure 11B, a partition wall 110 is formed on layer 4430-2, and a light-emitting layer 4421 is formed on layer 4430-2 exposed from the partition wall 110 in a top view using a wet method such as an inkjet method. Layers 4420-1, 4420-2, and the upper electrode 688 can be a common layer, and it is preferable that layers 4420-1, 4420-2, and the upper electrode 688 are formed over the partition wall 110 as shown in Figure 11B. It is preferable to make the common layer thicker so that it can overcome the partition wall 110. If there are constraints on making the common layer thicker, the light-emitting layer 4421 may be made thicker. In this case, for example, it is preferable to adjust the amount of solution dropped from the inkjet device so that the film thickness of the light-emitting layer is 2 / 3 times or more but less than 1 of the height of the partition wall 110.

[0151] Next, modified examples of Figures 11A and 11B are shown in Figures 11C1 and 11C2. In Figure 11C1, multiple light-emitting layers (a first light-emitting layer 4411, a second light-emitting layer 4412, and a third light-emitting layer 4413) are provided between layer 4420 and layer 4430. In Figure 11C2, multiple light-emitting layers (a first light-emitting layer 4411, and a second light-emitting layer 4412) are provided between layer 4420 and layer 4430.

[0152] In Figures 11C1 and 11C2, the partition wall 110 is positioned relative to the layer formed by the wet method. For example, by forming the partition wall 110 on layer 4430, one or more of the multiple light-emitting layers in Figures 11C1 and 11C2, specifically all of the light-emitting layers, can be formed by the wet method. Although not shown, the partition wall 110 has a first region and a second region of different heights as described in the above embodiment.

[0153] The light-emitting materials included in the multiple light-emitting layers in Figures 11C1 and 11C2 can be selected to be light-emitting materials of the same color or different colors. When light-emitting materials of the same color are selected, the driving voltage is increased, but the driving current can be reduced, which is advantageous in terms of increasing brightness and extending lifespan. In Figures 11C1 and 11C2, full-color display is made possible by coloring each light-emitting element with blue (B), green (G), and red (R) as the same color light-emitting material.

[0154] When selecting light-emitting materials of different colors, selecting materials that are complementary in color relationship can result in a light-emitting element that emits white light. For example, in Figure 11C1, by making the emission color of the first light-emitting layer 4411 the same as the emission color of the third light-emitting layer 4413, and using light-emitting materials such that the emission color of the second light-emitting layer 4412 is complementary to that emission color, white light can be obtained from the light-emitting element 20. Also, for example, in Figure 11C2, by using light-emitting materials such that the emission color of the first light-emitting layer 4411 and the emission color of the second light-emitting layer 4412 are complementary in color relationship, white light can be obtained from the light-emitting element 20. When white light is emitted and full-color display is desired, there is a method to obtain desired colors such as blue (B), green (G), and red (R) using a color filter or color conversion layer.

[0155] Figures 11C1 and 11C2 show configurations with three and two layers of light-emitting layers stacked, but configurations with four or more layers are also acceptable.

[0156] In Figures 11C1 and 11C2, the first light-emitting layer 4411 is formed on the layer 4430 exposed from the partition wall 110 by a wet method such as inkjet. The lower electrode 672 and the upper electrode 688 can be formed by vapor deposition, CVD, or sputtering. Layers 4430 and 4420 can be formed by a wet method or vapor deposition. Of these, layer 4420 and the upper electrode 688 can be shared among multiple light-emitting elements and are referred to as the common layer. The common layer is formed over the entire pixel area. The common layer is formed over the partition wall 110, but if it is not cut by the partition wall 110, the common layer should be made thicker. If there are limitations on thickening, the amount of solution dropped from the inkjet device should be adjusted so that the film thickness of the first light-emitting layer 4411, the second light-emitting layer 4412, or the third light-emitting layer 4413 is between 2 / 3 and 1 of the height of the partition wall 110.

[0157] Note that layer 4420 and layer 4430 in Figures 11C1 and 11C2 may be a laminated structure consisting of two or more layers, as shown in Figure 11B.

[0158] Next, modified examples of Figure 11C2 are shown in Figures 11D1 and 11D2. Both Figures 11D1 and 11D2 are examples of configurations in which light-emitting units are stacked. Both Figures 11D1 and 11D2 have a configuration in which a first light-emitting unit 686a and a second light-emitting unit 686b are present, with an intermediate layer 690 between them. In Figure 11D2, the intermediate layer has a stacked structure of intermediate layer 690a and intermediate layer 690b. The first light-emitting unit 686a has layer 4430-1, a first light-emitting layer 4411, and layer 4420-1. The second light-emitting unit 686b has layer 4430-2, a second light-emitting layer 4412, and layer 4420-2. A partition wall 110 is positioned between each layer that is formed by the wet method. For example, when the first light-emitting layer 4411 and the second light-emitting layer 4412 are formed by a wet process, a partition wall 110 is provided to separate the first light-emitting layer 4411 and the second light-emitting layer 4412. Although not shown, the partition wall 110 has a first region and a second region of different heights as described in the above embodiment.

[0159] Layers 4420-1 and 4430-1 are functional layers similar to layers 4420 and 4430, respectively. Layers 4420-2 and 4430-2 are functional layers similar to layers 4420 and 4430, respectively.

[0160] The intermediate layer 690 shown in Figure 11D1 has a dopant material in the same material as layer 4420-1, and an acceptor material in the same material as layer 4430-2.

[0161] Intermediate layer 690a, shown in Figure 11D2, is a layer having a dopant material in the same material as layer 4420-1, and intermediate layer 690b is a layer having an acceptor material in the same material as layer 4430-2.

[0162] In Figures 11D1 and 11D2, similar to Figure 11C2, the light-emitting materials included in the multiple light-emitting layers can be selected to be light-emitting materials of the same color or different colors. When light-emitting materials of the same color are selected, the driving voltage increases, but the driving current can be reduced, which is advantageous in terms of increasing brightness and extending lifespan. When light-emitting materials of different colors are selected, if the light-emitting materials are in a complementary color relationship, a light-emitting element that exhibits white light can be obtained.

[0163] In Figures 11D1 and 11D2, similar to Figure 11C2, when white light emission is observed and full-color display is desired, a color filter or color conversion layer can be used to obtain desired colors such as blue (B), green (G), and red (R).

[0164] In Figures 11D1 and 11D2, as in Figure 11C2, full-color display is made possible by coloring each light-emitting element with a different light-emitting color (for example, blue (B), green (G), and red (R)).

[0165] The color purity can be further enhanced by adding a microcavity structure to the light-emitting element 20 shown in Figure 11. The microcavity structure has a configuration in which the optical distance between the upper electrode 688 and the lower electrode 672 differs for each emitted color.

[0166] To make the optical distance between the upper electrode 688 and the lower electrode 672 different, it is preferable to make the thickness of the lower electrode 672 different. When the thickness of the lower electrode 672 is different, and the lower electrode 672 has a laminated structure of a first conductive film and a second conductive film on the first conductive film, it is easier to create a microcavity structure by making the thickness of the second conductive film different.

[0167] Here, we will explain examples of materials for each functional layer of the light-emitting element.

[0168] The hole injection layer is a layer that injects holes from the anode into the hole transport layer. Specifically, it can be formed from phthalocyanine-based complex compounds, aromatic amine compounds, or polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS).

[0169] Furthermore, the hole injection layer may be formed from an acceptor material. As an acceptor material, an organic compound having an electron-withdrawing group (halogen group, cyano group, etc.) can be used. In particular, compounds in which an electron-withdrawing group is bonded to a condensed aromatic ring having multiple heteroatoms, such as 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated as HAT-CN), are thermally stable and preferred. Also, [3]radialene derivatives having an electron-withdrawing group (especially halogen groups such as fluoro groups, cyano groups, etc.) are preferred because they have very high electron-accepting properties.

[0170] In addition to the organic compounds mentioned above, other acceptor materials that can be used include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, or manganese oxide. Among these, molybdenum oxide is preferred because it is stable in air, has low hygroscopicity, and is easy to handle. Furthermore, tin oxide, indium oxide, or titanium oxide may also be used. Acceptor materials can extract electrons from adjacent hole transport layers (or hole transport materials) by applying a voltage between the electrodes.

[0171] Furthermore, the hole injection layer may be formed from a composite material containing the acceptor material and the hole transport material. Various organic compounds can be used as the hole transport material in the composite material, such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, or polymer compounds (oligomers, dendrimers, polymers, etc.). Note that the hole transport material used in the composite material may be 1 × 10⁻⁶. -6 cm 2 It is preferable that the material has a hole mobility of / Vs or greater. The hole-transporting material used in the composite material is preferably a compound having a condensed aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the condensed aromatic hydrocarbon ring, anthracene rings or naphthalene rings are preferred. As the π-electron-rich heteroaromatic ring, a condensed aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, or a thiophene skeleton is preferred, specifically a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or heteroaromatic ring is further condensed thereon. In addition, other aromatic amine compounds can be used as the hole-transporting material.

[0172] The hole transport layer is a layer that transports holes injected from the anode by the hole injection layer to the light-emitting layer. The hole transport layer is a layer containing a hole-transporting material. The hole-transporting material is 1 × 10⁻¹⁶ -6 cm 2A material having a hole mobility of 1 / Vs or higher is preferred. Any material with higher hole transport capabilities than electron transport can be used as a hole-transporting material. Specifically, preferred hole-transporting materials include π-electron-rich heteroaromatic compounds or aromatic amines, which are materials with high hole transport capabilities.

[0173] As the π-electron-rich heteroaromatic ring, a condensed aromatic ring containing at least one of the pyrrole skeleton, furan skeleton, or thiophene skeleton is preferred, specifically a carbazole ring, a dibenzothiophene ring, or a ring obtained by further condensing an aromatic ring or heteroaromatic ring thereon.

[0174] The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light-emitting layer. The electron transport layer is a layer containing an electron-transporting material. The electron-transporting material is 1 × 10⁻¹⁶ -6 cm 2 Materials having an electron mobility of 1 / Vs or higher are preferred. However, any material that has higher electron transport capabilities than holes can also be used as an electron transport material. Preferred electron transport materials include metal complexes and organic compounds having a π-electron-deficient heteroaromatic ring skeleton. Specifically, in addition to metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, metal complexes having a thiazole skeleton, etc., materials with high electron transport capabilities such as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, or other π-electron-deficient heteroaromatic compounds containing nitrogen-containing heteroaromatic compounds can be used. In particular, heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, or heterocyclic compounds having a pyridine skeleton are preferred due to their good reliability. In particular, diazines (such as pyrimidines or pyrazines) or heterocyclic compounds having a triazine skeleton exhibit high electron transport properties and contribute to reducing the driving voltage.

[0175] The electron injection layer is a layer that injects electrons from the cathode to the electron transport layer, and is a layer containing a material with high electron injection properties. As the material with high electron injection properties, alkali metals, alkaline earth metals, or compounds or complexes thereof can be used. As the material for the electron injection layer, a layer containing alkali metals, alkaline earth metals, or compounds thereof within an electride or an electron-transporting substance can also be used.

[0176] Furthermore, an electron-transporting material may be used as the electron injection layer described above. For example, a compound having a noncommon pair of electrons and an electron-deficient heteroaromatic ring can be used as the electron-transporting material. Specifically, a compound having at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, or pyridazine ring), or a triazine ring, such as 4,7-diphenyl-1,10-phenanthroline (abbreviated as BPhen) or 2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), can be used.

[0177] The luminescent layer is a layer containing a luminescent material (also referred to as a luminescent substance). The luminescent layer may contain one or more types of luminescent substances. The luminescent substance can be any substance that exhibits a luminescent color such as blue, purple, blue-violet, green, yellow-green, yellow, orange, or red. A substance that emits near-infrared light can also be used as the luminescent substance.

[0178] As the light-emitting material, fluorescent materials, phosphorescent materials, materials that exhibit thermally activated delayed fluorescence (TADF) materials, or quantum dot materials can be used.

[0179] While known materials can be used as fluorescent materials, heteroaromatic diamine compounds or condensed aromatic diamine compounds are particularly preferred as blue fluorescent materials. Examples of such compounds include pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, or naphthalene derivatives. Condensed aromatic diamine compounds, particularly pyrenediamine compounds, are preferred because they have high hole-trapping properties and excellent luminescence efficiency and reliability.

[0180] Examples of phosphorescent materials include organometallic complexes (especially iridium complexes) having a 4H-triazole skeleton, 1H-triazole skeleton, imidazole skeleton, carbene skeleton, pyrimidine skeleton, pyrazine skeleton, pyridine skeleton, or quinoline skeleton; organometallic complexes (especially iridium complexes) using phenylpyridine derivatives having electron-withdrawing groups as ligands; platinum complexes; or rare earth metal complexes.

[0181] As TADF materials, you can use fullerenes and their derivatives, acridines and their derivatives, eosin derivatives, metal-containing porphyrins including magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), or heterocyclic compounds having one or both of a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring.

[0182] Among skeletons having a π-electron-deficient heteroaromatic ring, the pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, or pyridazine skeleton), and triazine skeleton are all stable and reliable and therefore preferred as TADF materials. In particular, the benzoflopyrimidine skeleton, benzothienopyrimidine skeleton, benzoflopyrazine skeleton, and benzothienopyrazine skeleton are all highly acceptable and reliable and therefore preferred as TADF materials. Furthermore, among skeletons having a π-electron-excess heteroaromatic ring, the acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are all stable and reliable, so it is preferable that the TADF material contains at least one of these skeletons. Dibenzofuran skeleton is preferred as the furan skeleton, and dibenzothiophene skeleton is preferred as the thiophene skeleton. Furthermore, as the pyrrole skeleton, indole skeleton, carbazole skeleton, indrocarbazole skeleton, bicarbazole skeleton, or 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole skeleton are particularly preferred.

[0183] Furthermore, when both a π-electron-deficient heteroaromatic ring and a π-electron-excess heteroaromatic ring are present, at least one of the π-electron-deficient skeleton or the π-electron-excess skeleton can be used instead. Examples of the π-electron-excess skeleton include aromatic amine skeletons or phenazine skeletons. Examples of the π-electron-deficient skeleton include xanthene skeletons, thioxanthene dioxide skeletons, oxadiazole skeletons, triazole skeletons, imidazole skeletons, anthraquinone skeletons, boron-containing skeletons such as phenylborane and volanthrene, aromatic rings having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, heteroaromatic rings, carbonyl skeletons such as benzophenone, phosphine oxide skeletons, or sulfone skeletons.

[0184] The light-emitting layer may contain one or more types of organic compounds (host material, assist material, etc.) in addition to the light-emitting substance (guest material). One or more of the above-mentioned hole-transporting materials and electron-transporting materials, or both, can be used as the one or more types of organic compounds. Alternatively, bipolar materials or TADF materials may be used as the one or more types of organic compounds.

[0185] The light-emitting layer preferably comprises, for example, a phosphorescent material, a hole-transporting material, and an electron-transporting material. The combination of the hole-transporting material and the electron-transporting material is one that readily forms an excited complex. With this configuration, light emission using ExTET (Exciplex-Triplet Energy Transfer), which is energy transfer from the excited complex to the light-emitting substance (phosphorescent material), can be efficiently obtained. By selecting a combination that forms an excited complex that exhibits light emission overlapping with the wavelength of the lowest-energy absorption band of the light-emitting substance, energy transfer becomes smoother, and light emission can be efficiently obtained. This configuration enables high efficiency, low-voltage operation, and long lifespan of the light-emitting element simultaneously.

[0186] In one aspect of the present invention, the light-emitting layer is produced by a wet method such as an inkjet method, but a solution obtained by dissolving or dispersing the above-mentioned various materials in a solvent can be used. In this case, various organic solvents can be used as the solvent. Alternatively, a mixture of polymer materials, low molecular weight materials, or dendrimers having a desired function can be used as a solution, either as is or dispersed or dissolved in a solvent.

[0187] Furthermore, if the light-emitting layer is to be composed of a polymer, a solution containing one or more monomers of the polymer material to be deposited is dispensed onto the film deposition surface, and the desired film can be formed by heating or irradiation with energy light to create crosslinking, condensation, polymerization, coordination, salt bonds, etc.

[0188] The above solution may also contain organic compounds with other functions, such as surfactants or viscosity modifiers.

[0189] As polymer materials, conjugated polymers, unconjugated polymers, pendant-type polymers, or dye-blended polymers can be used. Examples of conjugated polymers include poly(p-phenylenevinylene); PPV, polyalkylthiophene; PAT, poly(1,4-phenylene); PPP type, polyfluorene derivatives; poly(9,9-dialkylfluorene); PDAF, or copolymers thereof. Examples of pendant-type polymers include vinyl polymers, such as polyvinylcarbazole (PVK).

[0190] Furthermore, various organic solvents can be used as the solvent mentioned above, such as benzene, toluene, xylene, mesitylene, tetrahydrofuran, dioxane, ethanol, methanol, n-propanol, isopropanol, n-butanol, t-butanol, acetonitrile, dimethyl sulfoxide, dimethylformamide, chloroform, methylene chloride, carbon tetrachloride, ethyl acetate, hexane, or cyclohexane. In particular, using low-polarity benzene derivatives such as benzene, toluene, xylene, or mesitylene is preferable because it allows for the preparation of a solution of a suitable concentration and prevents deterioration of the materials contained in the solution due to oxidation. In addition, considering the uniformity of the film after preparation or the uniformity of the film thickness, it is preferable that the boiling point is 100°C or higher, and toluene, xylene, or mesitylene are even more preferable.

[0191] <Materials for layer 4430> In one aspect of the present invention, layer 4430 may be formed by a wet method in addition to the light-emitting layer. Since layer 4430 can be a common layer, a spin coating method is preferable as the wet method. Specifically, after forming the lower electrode 672, layer 4430 can be formed by a spin coating method or the like without performing patterning.

[0192] When the lower electrode 672 is the anode, it is preferable that layer 4430 contains both a highly hole-transporting framework and a material exhibiting acceptor properties. When layer 4430 is manufactured by a wet process, examples of materials exhibiting acceptor properties include sulfonic acid compounds, fluorine compounds, trifluoroacetic acid compounds, propionic acid compounds, or metal oxides.

[0193] When preparing layer 4430 by a wet process, if a solution of mixed monomers is applied, it is preferable to use a secondary amine and an aryl sulfonic acid as the monomers.

[0194] As the secondary amine, substituted or unsubstituted aryl groups having 6 to 14 carbon atoms, or substituted or unsubstituted π-electron-rich heteroaryl groups having 6 to 12 carbon atoms can be used. As the aryl group, for example, phenyl, biphenyl, naphthyl, fluorenyl, phenantrenyl, or anthryl groups can be used, and phenyl groups are preferred because they have good solubility and are inexpensive. As the heteroaryl group, carbazole skeletons, pyrrole skeletons, thiophene skeletons, furan skeletons, or imidazole skeletons can be used. Furthermore, having multiple bonds via arylamines or heteroarylamines is preferable as it improves film quality, and the resulting structure may be an oligomer or polymer. When there are multiple amines, some of the amines may be tertiary amines, and it is preferable that the proportion of secondary amines is greater than the proportion of tertiary amines. The number of amines is 1000 or less, more preferably 10 or less, and the molecular weight is preferably 100,000 or less. Furthermore, if fluorine is substituted, the compatibility with fluorine-substituted compounds is improved, which is preferable.

[0195] As a secondary amine, an organic compound represented by the following general formula (G1) is preferred.

[0196] [ka]

[0197] However, in the above general formula (G1), Ar 11 to Ar 13 one or more of which represent hydrogen, and Ar 14 to Ar 17 represent a substituted or unsubstituted aromatic ring having 6 to 14 carbon atoms, and Ar 14 to Ar 17 represent a substituted or unsubstituted aromatic ring having 6 to 14 carbon atoms. As the aromatic ring having 6 to 14 carbon atoms, a benzene ring, a bisbenzene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, or an anthracene ring can be used. Note that Ar 12 and Ar 16 , Ar 14 and Ar 16 , Ar 11 and Ar 14 , Ar 14 and Ar 15 , Ar 15 and Ar 17 , Ar 13 and Ar 17 may be bonded to each other to form a ring. Also, p represents an integer of 0 or more and 1000 or less, preferably 0 or more and 3 or less. Note that the molecular weight of the organic compound represented by the above general formula (G1) is preferably 100,000 or less.

[0198] As the tertiary amine, for example, an organic compound represented by the following general formula (G2) is preferable.

[0199]

Chemical formula

[0200] However, in the above general formula (G2), Ar 21 to Ar 23 represent a substituted or unsubstituted aryl group having 6 to 14 carbon atoms, and these may be bonded to each other to form a ring. Also, Ar 21 to Ar 23If the substituent has substituents, the substituent may be a group consisting of multiple diarylamino groups or carbazolyl groups linked together. It may also have ether bonds, sulfide bonds, or amine-mediated bonds, and when there are multiple aryl groups, these bonds are preferable as they improve solubility in organic solvents. If the substituent has alkyl groups, they may also be bonded via ether bonds, sulfide bonds, or amines.

[0201] As specific examples of secondary amines, it is preferable to use organic compounds represented by the following structural formulas (Am2-1) to (Am2-32). The organic compounds represented by the following structural formulas (Am2-1) to (Am2-32) have an NH group.

[0202] [ka]

[0203] [ka]

[0204] [ka]

[0205] [ka]

[0206] [ka]

[0207] Amine compounds can be mixed with sulfonic acid compounds and used in solutions. Mixing with sulfonic acid compounds facilitates carrier generation and improves conductivity. Mixing with sulfonic acid compounds is sometimes referred to as p-doping. Using a secondary amine as the amine compound is preferable because it can form bonds through dehydration reactions with the mixed sulfonic acid compound. When the compound to be mixed with the amine compound is a fluoride, using a fluoride as the amine compound, such as those with the above structural formulas (Am2-1), (Am2-22) to (Am2-28), or (Am2-31), is preferable because it improves compatibility.

[0208] Furthermore, thiophene derivatives may be used instead of secondary amines. Specific examples of thiophene derivatives include organic compounds represented by structural formulas (T-1) to (T-4) below, or polythiophene or poly(3,4-ethylenedioxythiophene) (PEDOT). Mixing thiophene derivatives with sulfonic acid compounds facilitates carrier generation and improves conductivity. This mixing with sulfonic acid compounds is sometimes referred to as p-doping.

[0209] [ka]

[0210] Sulfonic acid compounds are materials that exhibit acceptability. Examples of sulfonic acid compounds include aryl sulfonic acids. Aryl sulfonic acids only need to have a sulfo group, and can be sulfonic acids, sulfonates, alkoxysulfonic acids, halogenated sulfonic acids, or sulfonic acid anions. These sulfo groups may be multiple. The aryl group of the aryl sulfonic acid can be a substituted or unsubstituted aryl group having 6 to 16 carbon atoms. Examples of aryl groups include phenyl, biphenyl, naphthyl, fluorenyl, phenantrenyl, anthryl, or pyrenyl groups, with naphthyl groups being particularly preferred due to their good solubility and transportability in organic solvents. Aryl sulfonic acids may also have multiple aryl groups. Furthermore, aryl sulfonic acids with fluorine-substituted aryl groups are preferred because they allow for a deep (largely negative) adjustment of the LUMO level. Furthermore, arylsulfonic acid may have ether bonds, sulfide bonds, or amine-mediated bonds. When it has multiple aryl groups, the presence of these bonds improves solubility in organic solvents, which is preferable. Also, arylsulfonic acid may have alkyl groups as substituents, or these bonds may be mediated via ether bonds, sulfide bonds, or amines. Furthermore, arylsulfonic acid may be substituted with a polymer. Polyethylene, nylon, polystyrene, or polyfluorenylene can be used as the polymer, but polystyrene or polyfluorenylene are preferred due to their good conductivity.

[0211] Specific examples of compounds containing arylsulfonic acid (arylsulfonic acid compounds) include, for example, organic compounds represented by structural formulas (S-1) to (S-15) below. Polymers having sulfo groups, such as poly(4-styrenesulfonic acid) (PSS), can also be used. By using arylsulfonic acid compounds, electrons can be accepted from shallow HOMO electron donors (amine compounds, carbazole compounds, or thiophene compounds, etc.), and by mixing with the electron donor, hole implantation or hole transport from the electrode can be achieved. By using a fluorine compound instead of the arylsulfonic acid compound, the LUMO level can be adjusted to be deeper (having a more negative energy level).

[0212] [ka]

[0213] [ka]

[0214] [ka]

[0215] [ka]

[0216] A tertiary amine may be further added to the solution obtained by mixing the above-mentioned secondary amine and sulfonic acid compound. Tertiary amines are more electrochemically and photochemically stable than secondary amines, and when mixed, they exhibit good hole transport properties. As the tertiary amine, organic compounds represented by the following structural formulas (Am3-1) to (Am3-7) are preferred. In addition to the tertiary amine, other materials with hole transport properties may be appropriately added to the solution.

[0217] [ka]

[0218] [ka]

[0219] In addition to aryl sulfonic acid compounds, cyano compounds such as tetracyanoquinodimethane compounds can also be used as electron acceptors. Specifically, examples include 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) or dipyradino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonnitrile (HAT-CN6).

[0220] Furthermore, it is preferable that the solution obtained by mixing the above monomers contains either or both of a 3,3,3-trifluoropropyltrimethoxysilane compound or a phenyltrimethoxysilane compound, as this improves wettability when a film is formed by a wet process.

[0221] When a layer deposited by a wet process using a solution containing an electron donor such as a secondary amine or thiophene and at least two monomers of arylsulfonic acid is measured by ToF-SIMS, a signal is observed around m / z=80 in the negative mode. The signal at m / z=80 originates from the SO3 anion in the arylsulfonic acid. On the other hand, signals originating from the amine monomer are not easily observed in the above layer. If a light-emitting device having this layer exhibits sufficient luminescence, it is evidence that the layer possesses sufficient hole transport ability. When the above signal and other analytical results are obtained in a light-emitting device that can emit light, it is found that the layer has sufficient hole transport ability, and the absence of observation of the amine or other skeleton responsible for hole transport suggests that the monomers are bonded together to form a polymer compound film. The above analytical results indicate that the layer was formed by a wet process.

[0222] Incidentally, the sulfonic acid compound represented by the above structural formula (S-1) or (S-2) has many sulfo groups and can form a three-dimensional bond with an amine compound, and is preferable because the film quality is likely to be stable. In addition to the signal at m / z = 80, a signal at m / z = 901 is observed in the negative mode in the layer formed using the arylsulfonic acid compound. A signal at m / z = 328 is also observed as a product ion.

[0223] <Light-emitting material> Incidentally, in the light-emitting device according to one aspect of the present invention, it is preferable to use an iridium complex represented by the following structural formula as a light-emitting material. Since the following iridium complex has an alkyl group, it is easily soluble in an organic solvent and is preferable for preparing a solution.

[0224]

Chemical formula

[0225] When the light-emitting layer containing the iridium complex represented by the above structural formula is measured by ToF-SIMS, it has been found that signals appear at m / z = 1676 or product ions m / z = 1181 and m / z = 685 in the positive mode result.

[0226] When the intermediate layer is a single layer as shown in FIG. 11D1, an organic compound layer containing an acceptor material and a donor material may be used for the intermediate layer.

[0227] When the intermediate layer is a two-layer structure as shown in FIG. 11D2, the intermediate layer preferably has an organic compound layer containing an acceptor material and an organic compound layer containing a donor material.

[0228] The organic compound layer containing the acceptor material is preferably formed using the composite material listed as the material that can constitute the above-mentioned hole injection layer or hole transport layer.

[0229] Acceptor materials are materials that can generate holes in an organic compound by separating its charge from another organic compound whose LUMO level value is close to that of the HOMO level value. For example, as organic acceptor materials, compounds having electron-withdrawing groups (halogen groups or cyano groups), such as quinodimethane derivatives, chloranil derivatives, or hexaazatriphenylene derivatives, can be used. For example, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F4-TCNQ), 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane, chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexazatriphenylene (abbreviated as HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated as F6-TCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene)malononitrile, etc. can be used. Furthermore, among organic acceptor materials, compounds in which an electron-withdrawing group is bonded to a condensed aromatic ring having multiple heteroatoms, such as HAT-CN, are particularly suitable because they have high acceptability and the film quality is stable with respect to heat. In addition, radialene derivatives having an electron-withdrawing group (especially a halogen group such as a fluoro group or a cyano group) [3] are also preferred because they have very high electron-accepting properties. Specifically, α,α',α''-1,2,3-cyclopropanetriylidenates[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenates[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenates[2,3,4,5,6-pentafluorobenzeneacetonitrile] can be used.

[0230] The donor material can be a substance with high electron injection potential, such as alkali metals, alkaline earth metals, rare earth metals, and compounds thereof. Examples of alkali metal compounds include oxides or halides such as lithium oxide, and alkali metal compounds also include carbonates such as lithium carbonate or cesium carbonate. Alkaline earth metal compounds include oxides, halides, or carbonates, and rare earth metal compounds also include oxides, halides, or carbonates.

[0231] The organic compound layer containing the donor material can be formed using the same material as that used to constitute the electron transport layer or electron injection layer described above.

[0232] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0233] (Embodiment 3) In this embodiment, an example of a pixel circuit configuration and an example of a driving method applicable to a display device according to one aspect of the present invention will be described.

[0234] [Example of pixel circuit configuration] The pixel circuit PIX1 shown in Figure 12A includes transistors M1 and M2, capacitor C1, and light-emitting element EL. Wirings SL, GL, AL, and CL are electrically connected to the pixel circuit PIX1.

[0235] Transistor M1's gate is electrically connected to wiring GL, one of its source and drain is electrically connected to wiring SL, and the other of its source and drain is electrically connected to the gate of transistor M2 and one of the electrodes of capacitor C1. Transistor M2's source and drain are electrically connected to wiring AL, and the other of its source and drain is electrically connected to the anode of light-emitting element EL. Capacitor C1's other electrode is electrically connected to the anode of light-emitting element EL. Light-emitting element EL's cathode is electrically connected to wiring CL.

[0236] Transistor M1 can also be called a selection transistor and functions as a switch to control the selection and deselection of pixels. Transistor M2 can also be called a drive transistor and has the function of controlling the current flowing to the light-emitting element EL. Capacitor C1 functions as a holding capacitor and has the function of holding the gate potential of transistor M2. Capacitor C1 may be a capacitive element such as an MIM capacitor, or the capacitance between the wiring or the gate capacitance of the transistor may be used as capacitor C1.

[0237] The source signal is supplied to wiring SL. Wiring SL can be formed using the same conductive layer as the conductive layer that functions as the source or drain of the transistor. The gate signal is supplied to wiring GL. Wiring GL can be formed using the same conductive layer as the conductive layer that functions as the gate of the transistor. A constant potential is supplied to wiring AL and wiring CL, respectively.

[0238] The anode side of the light-emitting element (EL) can be set to a high potential, and the cathode side to a lower potential than the anode side, allowing the anode to correspond to the positive electrode and the cathode to the negative electrode.

[0239] The pixel circuit PIX2 shown in Figure 12B is configured by adding transistor M3 to the pixel circuit PIX1. Furthermore, wiring V0 is electrically connected to the pixel circuit PIX2.

[0240] Transistor M3 is electrically connected to wiring GL at its gate, and to wiring V0 at wiring V0, with one of its source and drains connected to the anode of the light-emitting element EL.

[0241] Wiring V0 provides a constant potential when writing data to the pixel circuit PIX2. This suppresses variations in the gate-source voltage of transistor M3.

[0242] The pixel circuit PIX3 shown in Figure 12C is an example where transistors with a pair of electrically connected gates are applied to transistors M1 and M2 of the pixel circuit PIX1. Similarly, the pixel circuit PIX4 shown in Figure 12D is an example where transistors with a pair of electrically connected gates are applied to pixel circuit PIX2. This increases the current that the transistors can supply. Here, transistors with a pair of electrically connected gates are used for all transistors, but this is not the only option. Transistors with a pair of gates that are electrically connected to different wirings may also be used. For example, reliability can be improved by using a transistor in which one of the gates and the source are electrically connected.

[0243] The pixel circuit PIX5 shown in Figure 13A is configured by adding transistor M4 to the above-mentioned PIX2. Furthermore, three wires (wires GL1, GL2, and GL3) that function as gate lines are electrically connected to the pixel circuit PIX5.

[0244] Transistor M4 has its gate electrically connected to wiring GL3, and one of its source and drain is electrically connected to the gate of transistor M2, while the other is electrically connected to wiring V0. Also, the gate of transistor M1 is electrically connected to wiring GL1, and the gate of transistor M3 is electrically connected to wiring GL2. Wiring V0 may be positioned to intersect with wiring AL.

[0245] By simultaneously making transistors M3 and M4 conduct, the source and gate of transistor M2 become at the same potential, making transistor M2 non-conducting. This allows the current flowing to the light-emitting element EL to be forcibly interrupted. Such a pixel circuit is suitable for display methods that alternate between display periods and off periods.

[0246] The pixel circuit PIX6 shown in Figure 13B is an example where a capacitor C2 is added to the pixel circuit PIX5 described above. Capacitor C2 functions as a retaining capacitor.

[0247] The pixel circuit PIX7 shown in FIG. 13C and the pixel circuit PIX8 shown in FIG. 13D are examples of applying a transistor having a pair of gates to the pixel circuit PIX5 or the pixel circuit PIX6 described above. Transistors M1, M3, and M4 are transistors to which a pair of gates are electrically connected, and transistor M2 is a transistor to which one gate is electrically connected to the source.

[0248] 〔Example of driving method〕 Hereinafter, an example of a driving method for a display device to which the pixel circuit PIX5 is applied will be described. Note that the same driving method can be applied to the pixel circuits PIX6, PIX7, and PIX8.

[0249] FIG. 14 shows a timing chart for a driving method of a display device to which the pixel circuit PIX5 is applied. Here, the potential transitions of the wiring GL1[k], wiring GL2[k], and wiring GL3[k] which are the gate lines of the k-th row, and the wiring GL1[k+1], wiring GL2[k+1], and wiring GL3[k+1] which are the gate lines of the (k + 1)-th row are shown. In addition, FIG. 14 shows the timing of signals applied to the wiring SL functioning as a source line.

[0250] Here, an example of a driving method in which one horizontal period is divided into a lighting period and a non-lighting period for display is shown. Also, the horizontal periods of the k-th row and the (k + 1)-th row are shifted only by the gate line selection period.

[0251] During the lighting period of the k-th row, first, a high-level potential is applied to the wiring GL1[k] and the wiring GL2[k], and a source signal is applied to the wiring SL. As a result, transistors M1 and M3 become conductive, and a potential corresponding to the source signal is written from the wiring SL to the gate of transistor M2. Thereafter, by applying a low-level potential to the wiring GL1[k] and the wiring GL2[k], transistors M1 and M3 become non-conductive, and the gate potential of transistor M2 is held.

[0252] Next, the process transitions to the illumination period of the (k+1)th row, and data is written using the same procedure as described above.

[0253] Next, let's explain the off-period. During the off-period of the k-th row, a high-level potential is applied to wiring GL2[k] and wiring GL3[k]. This causes transistors M3 and M4 to conduct, and as the same potential is supplied to the source and gate of transistor M2, almost no current flows through transistor M2. As a result, the light-emitting element EL turns off. All pixels located in the k-th row turn off. The pixels in the k-th row remain off until the next on-period.

[0254] Next, the process transitions to the blackout period for row k+1, and as described above, all pixels in row k+1 become black.

[0255] Thus, a driving method that includes periods of the light being off during a horizontal display period, rather than remaining lit the entire time, can also be called duty cycle driving. By using duty cycle driving, the afterimage phenomenon when displaying videos can be reduced, thus enabling the creation of display devices with high video display performance. In particular, in VR devices, reducing afterimages can alleviate so-called VR sickness.

[0256] In duty cycle operation, the ratio of the lighting period to the horizontal period can be called the duty cycle. For example, a duty cycle of 50% means that the lighting period and the off period are of equal length. The duty cycle can be freely set and can be adjusted as appropriate within a range of, for example, higher than 0% and less than or equal to 100%.

[0257] The above is an explanation of the driving method examples.

[0258] The details described in this embodiment can be used in combination with other embodiments.

[0259] (Embodiment 4) This embodiment describes an example of the configuration of a display device according to one aspect of the present invention.

[0260] The display device of this embodiment can be a high-resolution display device or a large-screen display device. Therefore, the display device of this embodiment can be used in electronic devices with relatively large screens, such as television sets, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as in the display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, smartphones, smartwatches, tablet devices, personal digital assistants, and audio playback devices.

[0261] [Display device 400A] Figure 15 shows a perspective view of the display device 400A, and Figure 16A shows a cross-sectional view of the display device 400A.

[0262] The display device 400A has a configuration in which substrate 452 and substrate 451 are bonded together. In Figure 15, substrate 452 is clearly indicated by a dashed line.

[0263] The display device 400A includes a display unit 462, a circuit 464, wiring 465, etc. Figure 15 shows an example in which IC 473 and FPC 472 are mounted on the display device 400A. Therefore, the configuration shown in Figure 15 can also be described as a display module having the display device 400A, an IC (integrated circuit), and an FPC.

[0264] For example, a scan line drive circuit can be used as circuit 464.

[0265] Wiring 465 has the function of supplying signals and power to the display unit 462 and the circuit 464. These signals and power are input to wiring 465 from an external source via FPC 472 or from IC 473.

[0266] Figure 15 shows an example in which IC 473 is mounted on substrate 451 using COG (Chip On Glass) or COF (Chip On Film) methods. IC 473 can be an IC having, for example, a scan line drive circuit or a signal line drive circuit. Note that the display device 400A and the display module may be configured without an IC. Alternatively, the IC may be mounted on an FPC using the COF method or the like.

[0267] Figure 16A shows an example of a cross-section obtained by cutting a portion of the display device 400A, including the FPC 472, a portion of the circuit 464, a portion of the display unit 462, and a portion of the area including the end.

[0268] The display device 400A shown in Figure 16A has a transistor 201, a transistor 205, a light-emitting element 430a that emits red light, a light-emitting element 430b that emits green light, and a light-emitting element 430c that emits blue light, etc., between substrates 451 and 452.

[0269] The light-emitting elements 430a, 430b, and 430c can be the light-emitting elements exemplified in Embodiments 1 to 3.

[0270] Here, if a pixel of a display device has three types of subpixels, each having a light-emitting element that emits a different color, examples of these three subpixels include combinations of R, G, and B, or combinations of yellow (Y), cyan (C), and magenta (M). If a pixel of a display device has four subpixels, examples of these four subpixels include combinations of R, G, B, and white (W), or combinations of R, G, B, and Y. A pixel can have three or more subpixels as the smallest unit capable of full-color display.

[0271] The protective layer 416 and the substrate 452 are bonded together via an adhesive layer 442. For sealing the light-emitting element, a solid sealing structure or a hollow sealing structure can be applied. In Figure 16A, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 is filled with an inert gas (such as nitrogen or argon), demonstrating the application of a hollow sealing structure. The adhesive layer 442 may be provided overlapping the light-emitting element. Alternatively, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from that of the adhesive layer 442.

[0272] The light-emitting elements 430a, 430b, and 430c have an optical adjustment layer between the pixel electrode and the hole injection layer 431. Light-emitting element 430a has an optical adjustment layer 426a, light-emitting element 430b has an optical adjustment layer 426b, and light-emitting element 430c has an optical adjustment layer 426c. Details of the light-emitting elements can be found in Embodiments 1 to 3.

[0273] The pixel electrodes 411a, 411b, and 411c are each connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214.

[0274] The edges of the pixel electrodes and optical adjustment layer are covered by an insulating layer 421 via a hole injection layer 431. The hole injection layer 431 may be provided over the entire surface of the display unit 462, or it may be divided into sub-pixel regions. An emissive layer is provided in the opening of the insulating layer 421, and a layer 435 having an electron transport layer and an electron injection layer is provided on the insulating layer 421, and a counter electrode 418 is provided on the layer 435. The pixel electrodes contain a material that reflects visible light, and the counter electrode 418 contains a material that transmits visible light.

[0275] The light emitted by the light-emitting element is directed towards the substrate 452. It is preferable to use a material with high transmittance to visible light for the substrate 452.

[0276] The insulating layer 421 may also be a laminated structure of an inorganic insulating film and an organic insulating film. When the insulating layer 421 is a laminated structure of an inorganic insulating film and an organic insulating film, it is preferable that the inorganic insulating film be the lower layer. In one embodiment of the present invention, the insulating layer 421 is provided on the hole injection layer 431, so by providing the inorganic insulating film on the hole injection layer 431 side, it is possible to suppress adverse effects on the hole injection layer 431 that are a concern when an organic solvent is used to form the organic insulating film.

[0277] Both transistors 201 and 205 are formed on the substrate 451. These transistors can be manufactured using the same materials and processes.

[0278] On the substrate 451, insulating layers 211, 213, 215, and 214 are provided in this order. A portion of insulating layer 211 functions as a gate insulating layer for each transistor. A portion of insulating layer 213 functions as a gate insulating layer for each transistor. Insulating layer 215 is provided covering the transistors. Insulating layer 214 is provided covering the transistors and functions as a planarization layer. The number of gate insulating layers and insulating layers covering the transistors are not limited and may be a single layer or two or more layers, respectively.

[0279] It is preferable to use a material that does not easily allow impurities such as water and hydrogen to diffuse into at least one layer of the insulating layer covering the transistor. This allows the insulating layer to function as a barrier layer. With such a configuration, the diffusion of impurities from the outside into the transistor can be effectively suppressed, thereby improving the reliability of the display device.

[0280] It is preferable to use inorganic insulating films for insulating layer 211, insulating layer 213, and insulating layer 215. Examples of inorganic insulating films that can be used include silicon nitride film, silicon oxide nitride film, silicon oxide film, silicon nitride oxide film, aluminum oxide film, and aluminum nitride film. Alternatively, hafnium oxide film, yttrium oxide film, zirconium oxide film, gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, cerium oxide film, and neodymium oxide film may also be used. Furthermore, two or more of the above insulating films may be laminated together.

[0281] Here, organic insulating films often have lower barrier properties than inorganic insulating films. Therefore, it is preferable that the organic insulating film has an opening near the edge of the display device 400A. This prevents impurities from entering through the organic insulating film from the edge of the display device 400A. Alternatively, the organic insulating film may be formed so that its edge is inward from the edge of the display device 400A, so that the organic insulating film is not exposed at the edge of the display device 400A.

[0282] An organic insulating film is preferred for the insulating layer 214, which functions as a planarizing layer. Examples of materials that can be used as the organic insulating film include acrylic resins, polyimide resins, epoxy resins, polyamide resins, polyimidoamide resins, siloxane resins, benzocyclobutene resins, phenolic resins, and precursors of these resins.

[0283] In the region 228 shown in Figure 16A, an opening is formed in the insulating layer 214. This prevents impurities from entering the display unit 462 from the outside through the insulating layer 214, even when an organic insulating film is used for the insulating layer 214. Therefore, the reliability of the display device 400A can be improved.

[0284] Transistors 201 and 205 have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as source and drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0285] The transistor structure of the display device of this embodiment is not particularly limited. For example, planar transistors, staggered transistors, inverse staggered transistors, etc., can be used. Furthermore, either a top-gate or bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below the semiconductor layer in which the channel is formed.

[0286] Transistors 201 and 205 are configured in which a semiconductor layer on which a channel is formed is sandwiched between two gates. The transistors may be driven by connecting the two gates and supplying them with the same signal. Alternatively, the threshold voltage of the transistors may be controlled by applying a potential to control the threshold voltage to one of the two gates and a potential to drive the other gate.

[0287] The crystallinity of the semiconductor material used in the transistor is not particularly limited; amorphous semiconductors, single-crystal semiconductors, or semiconductors with crystalline properties other than single crystals (microcrystalline semiconductors, polycrystalline semiconductors, or semiconductors with crystalline regions in part) may be used. Using a single-crystal semiconductor or a semiconductor with crystalline properties is preferable because it can suppress the degradation of transistor characteristics.

[0288] The semiconductor layer of the transistor preferably has a metal oxide (also called an oxide semiconductor). In other words, the display device of this embodiment preferably uses a transistor (hereinafter referred to as an OS transistor) that uses a metal oxide in the channel formation region. Alternatively, the semiconductor layer of the transistor may have silicon. Examples of silicon include amorphous silicon and crystalline silicon (low-temperature polysilicon, single-crystal silicon, etc.).

[0289] The semiconductor layer preferably comprises, for example, indium, M (where M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more selected from aluminum, gallium, yttrium, and tin.

[0290] In particular, it is preferable to use an oxide (also written as IGZO) containing indium (In), gallium (Ga), and zinc (Zn) as the semiconductor layer.

[0291] When the semiconductor layer is an In-M-Zn oxide, it is preferable that the atomic ratio of In in the In-M-Zn oxide is equal to or greater than the atomic ratio of M. Examples of such In-M-Zn oxide atomic ratios of metal elements include compositions where In:M:Zn=1:1:1 or close to it, In:M:Zn=1:1:1.2 or close to it, In:M:Zn=2:1:3 or close to it, In:M:Zn=3:1:2 or close to it, In:M:Zn=4:2:3 or close to it, In:M:Zn=4:2:4.1 or close to it, In:M:Zn=5:1:3 or close to it, In:M:Zn=5:1:6 or close to it, In:M:Zn=5:1:7 or close to it, In:M:Zn=5:1:8 or close to it, In:M:Zn=6:1:6 or close to it, In:M:Zn=5:2:5 or close to it, and so on. Note that "close to it" compositions include a range of ±30% of the desired atomic ratio.

[0292] For example, when describing a composition with an atomic ratio of In:Ga:Zn = 4:2:3 or a similar ratio, it includes cases where, when the atomic ratio of In is 4, the atomic ratio of Ga is between 1 and 3, and the atomic ratio of Zn is between 2 and 4. Also, when describing a composition with an atomic ratio of In:Ga:Zn = 5:1:6 or a similar ratio, it includes cases where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is between 5 and 7. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn = 1:1:1 or a similar ratio, it includes cases where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is greater than 0.1 and 2 or less.

[0293] The transistors in circuit 464 and the transistors in display unit 462 may have the same structure or different structures. The structures of the multiple transistors in circuit 464 may all be the same or there may be two or more different structures. Similarly, the structures of the multiple transistors in display unit 462 may all be the same or there may be two or more different structures.

[0294] A connection portion 204 is provided in the region of substrate 451 where substrate 452 does not overlap. At the connection portion 204, wiring 465 is electrically connected to FPC 472 via conductive layer 466 and connection layer 242. The conductive layer 466 is shown as an example of a laminated structure consisting of a conductive film obtained by processing the same conductive film as the pixel electrode and a conductive film obtained by processing the same conductive film as the optical adjustment layer. The conductive layer 466 is exposed on the upper surface of the connection portion 204. This allows the connection portion 204 and FPC 472 to be electrically connected via the connection layer 242.

[0295] It is preferable to provide a light-shielding layer 417 on the surface of the substrate 452 that faces the substrate 451. Various optical components can also be arranged on the outside of the substrate 452. Examples of optical components include polarizing plates, phase difference plates, light diffusion layers (such as diffusion films), anti-reflective layers, and light-collecting films. Furthermore, an antistatic film to suppress the adhesion of dust, a water-repellent film to make it difficult for dirt to adhere, a hard coat film to suppress the occurrence of scratches during use, and an impact-absorbing layer may also be arranged on the outside of the substrate 452.

[0296] By providing a protective layer 416 that covers the light-emitting element, it is possible to suppress the ingress of impurities such as water into the light-emitting element and improve the reliability of the light-emitting element.

[0297] In the region 228 near the edge of the display device 400A, it is preferable that the insulating layer 215 and the protective layer 416 are in contact with each other through an opening in the insulating layer 214. In particular, it is preferable that the inorganic insulating film of the insulating layer 215 and the inorganic insulating film of the protective layer 416 are in contact with each other. This makes it possible to suppress the entry of impurities into the display unit 462 from the outside through the organic insulating film. Therefore, the reliability of the display device 400A can be improved.

[0298] Figure 16B shows an example where the protective layer 416 has a three-layer structure. In Figure 16B, the protective layer 416 has an inorganic insulating layer 416a on the light-emitting element 430c, an organic insulating layer 416b on the inorganic insulating layer 416a, and an inorganic insulating layer 416c on the organic insulating layer 416b.

[0299] The edges of the inorganic insulating layer 416a and the inorganic insulating layer 416c extend outward beyond the edge of the organic insulating layer 416b and are in contact with each other. Furthermore, the inorganic insulating layer 416a is in contact with the insulating layer 215 (inorganic insulating layer) through an opening in the insulating layer 214 (organic insulating layer). As a result, the light-emitting element can be surrounded by the insulating layer 215 and the protective layer 416, thereby increasing the reliability of the light-emitting element.

[0300] Thus, the protective layer 416 may have a laminated structure of an organic insulating film and an inorganic insulating film. In this case, it is preferable that the edges of the inorganic insulating film extend outward more than the edges of the organic insulating film.

[0301] Substrates 451 and 452 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, etc., respectively. The substrate on the side that extracts light from the light-emitting element should be made of a material that transmits the light. Using flexible materials for substrates 451 and 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used as substrate 451 or substrate 452.

[0302] Substrates 451 and 452 can be made from polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamide-imide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. One or both of substrates 451 and 452 may be made of glass of a thickness sufficient to provide flexibility.

[0303] Furthermore, when a circular polarizing plate is superimposed on a display device, it is preferable to use a substrate with high optical isotropy for the substrate of the display device. A substrate with high optical isotropy has low birefringence (or a small amount of birefringence).

[0304] For substrates with high optical isotropy, the absolute value of the retardation (phase difference) is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0305] Examples of films with high optical isotropy include triacetylcellulose (TAC, also known as cellulose triacetate) film, cycloolefin polymer (COP) film, cycloolefin copolymer (COC) film, and acrylic film.

[0306] Furthermore, when using a film as the substrate, the film may absorb water, potentially causing wrinkles or other shape changes in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferable to use a film with a water absorption rate of 0.1% or less, and even more preferable to use a film with a water absorption rate of 0.01% or less.

[0307] Various types of curing adhesives can be used as the adhesive layer, including UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of these adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. Materials with low moisture permeability, such as epoxy resins, are particularly preferred. Two-component mixed resins may also be used. Adhesive sheets may also be used.

[0308] As the connecting layer 242, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), etc., can be used.

[0309] Materials that can be used for conductive layers such as the gate, source, and drain of transistors, as well as various wirings and electrodes that constitute display devices, include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, as well as alloys mainly composed of these metals. Films containing these materials can be used as single layers or in a multilayer structure.

[0310] Furthermore, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene can be used as the light-transmitting conductive material. Alternatively, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metallic materials, can be used. Alternatively, nitrides of such metallic materials (e.g., titanium nitride) may be used. When using metallic materials or alloy materials (or their nitrides), it is preferable to make them thin enough to be light-transmitting. In addition, a laminated film of the above materials can be used as a conductive layer. For example, using a laminated film of a silver-magnesium alloy and indium tin oxide is preferable because it can enhance conductivity. These can also be used for conductive layers of various wirings and electrodes that constitute a display device, and for conductive layers of light-emitting elements (conductive layers that function as pixel electrodes or common electrodes).

[0311] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxide nitride, silicon nitride, silicon oxide, and aluminum oxide.

[0312] [Display device 400B] Figure 17 shows a cross-sectional view of the display device 400B. The perspective view of the display device 400B is the same as that of the display device 400A (Figure 15). Figure 17 shows examples of cross-sections of the display device 400B when a portion of the area including the FPC 472, a portion of the circuit 464, and a portion of the display unit 462 are cut. Note that explanations of parts that are the same as those of the display device 400A may be omitted.

[0313] The display device 400B has a configuration in which substrate 452 and substrate 451 are bonded together.

[0314] The display device 400B includes a display unit 462, a circuit 464, wiring 465, etc. Therefore, the display device 400B shown in Figure 17 can also be described as a display module having the display device 400B, an IC (integrated circuit), and an FPC.

[0315] For example, a scan line drive circuit can be used as circuit 464.

[0316] Wiring 465 has the function of supplying signals and power to the display unit 462 and the circuit 464. These signals and power are input to wiring 465 from an external source via FPC 472 or from IC 473.

[0317] The display module shows an example where IC473 is mounted on the substrate 451 using a COG (Chip On Glass) method or COF (Chip On Film) method. IC473 can be an IC having, for example, a scan line drive circuit or a signal line drive circuit. Note that the display device 400B and the display module may also be configured without an IC. Alternatively, the IC may be mounted on an FPC using a COF method or the like.

[0318] Figure 17 shows an example of a cross-section obtained by cutting a portion of the display device 400B, including the FPC 472, a portion of the circuit 464, a portion of the display unit 462, and a portion of the area including the end.

[0319] The display device 400B shown in Figure 17 has a transistor 201, a transistor 205, a light-emitting element 430a that emits red light, a light-emitting element 430b that emits green light, and a light-emitting element 430c that emits blue light, etc., between substrates 451 and 452.

[0320] The light-emitting elements 430a, 430b, and 430c can be the light-emitting elements exemplified in Embodiments 1 to 3.

[0321] Here, if the pixels of the display device have three types of subpixels that have light-emitting elements that emit different colors from each other, examples of such three subpixels include subpixels of three colors: R, G, and B; and subpixels of three colors: yellow (Y), cyan (C), and magenta (M). If there are four such subpixels, examples of such four subpixels include subpixels of four colors: R, G, B, and white (W); and subpixels of four colors: R, G, B, and Y.

[0322] The protective layer 416 and the substrate 452 are bonded together via an adhesive layer 442. For sealing the light-emitting element, a solid sealing structure or a hollow sealing structure can be applied. In Figure 17, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 is filled with an inert gas (such as nitrogen or argon), indicating a hollow sealing structure. The adhesive layer 442 may be provided overlapping the light-emitting element. Alternatively, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from that of the adhesive layer 442.

[0323] The light-emitting elements 430a, 430b, and 430c have an optical adjustment layer between the pixel electrode and the hole injection layer 431. Light-emitting element 430a has an optical adjustment layer 426a, light-emitting element 430b has an optical adjustment layer 426b, and light-emitting element 430c has an optical adjustment layer 426c. Details of the light-emitting elements can be found in Embodiments 1 to 3.

[0324] The pixel electrodes 411a, 411b, and 411c are each connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214.

[0325] The edges of the pixel electrodes and optical adjustment layer are covered by an insulating layer 421 via a hole injection layer 431. The hole injection layer 431 may be provided over the entire surface of the display unit 462, or it may be divided into sub-pixel regions. An emissive layer is provided in the opening of the insulating layer 421, and a layer 435 having an electron transport layer and an electron injection layer is provided on the insulating layer 421, and a counter electrode 418 is provided on the layer 435. The pixel electrodes contain a material that transmits visible light, and the counter electrode 418 contains a material that reflects visible light.

[0326] The light emitted by the light-emitting element is projected towards the substrate 454. It is preferable to use a material with high transmittance to visible light for the substrate 454.

[0327] The insulating layer 421 may also be a laminated structure of an inorganic insulating film and an organic insulating film. When the insulating layer 421 is a laminated structure of an inorganic insulating film and an organic insulating film, it is preferable that the inorganic insulating film be the lower layer. In one embodiment of the present invention, the insulating layer 421 is provided on the hole injection layer 431, so by providing the inorganic insulating film on the hole injection layer 431 side, it is possible to suppress adverse effects on the hole injection layer 431 that are a concern when an organic solvent is used to form the organic insulating film.

[0328] Both transistors 201 and 205 are formed on the substrate 451. These transistors can be manufactured using the same materials and processes.

[0329] On the substrate 451, insulating layers 211, 213, 215, and 214 are provided in this order. A portion of insulating layer 211 functions as a gate insulating layer for each transistor. A portion of insulating layer 213 functions as a gate insulating layer for each transistor. Insulating layer 215 is provided covering the transistors. Insulating layer 214 is provided covering the transistors and functions as a planarization layer. The number of gate insulating layers and insulating layers covering the transistors are not limited and may be a single layer or two or more layers, respectively.

[0330] It is preferable to use a material that does not easily allow impurities such as water and hydrogen to diffuse into at least one layer of the insulating layer covering the transistor. This allows the insulating layer to function as a barrier layer. With such a configuration, the diffusion of impurities from the outside into the transistor can be effectively suppressed, thereby improving the reliability of the display device.

[0331] It is preferable to use inorganic insulating films for insulating layer 211, insulating layer 213, and insulating layer 215. Examples of inorganic insulating films that can be used include silicon nitride film, silicon oxide nitride film, silicon oxide film, silicon nitride oxide film, aluminum oxide film, and aluminum nitride film. Alternatively, hafnium oxide film, yttrium oxide film, zirconium oxide film, gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, cerium oxide film, and neodymium oxide film may also be used. Furthermore, two or more of the above insulating films may be laminated together.

[0332] Here, organic insulating films often have lower barrier properties than inorganic insulating films. Therefore, it is preferable that the organic insulating film has an opening near the edge of the display device 400B. This prevents impurities from entering through the organic insulating film from the edge of the display device 400B. Alternatively, the organic insulating film may be formed so that its edge is inward from the edge of the display device 400B, so that the organic insulating film is not exposed at the edge of the display device 400B.

[0333] An organic insulating film is preferred for the insulating layer 214, which functions as a planarizing layer. Examples of materials that can be used as the organic insulating film include acrylic resins, polyimide resins, epoxy resins, polyamide resins, polyimidoamide resins, siloxane resins, benzocyclobutene resins, phenolic resins, and precursors of these resins.

[0334] In the region 228 shown in Figure 17, an opening is formed in the insulating layer 214. This prevents impurities from entering the display unit 462 from the outside through the insulating layer 214, even when an organic insulating film is used for the insulating layer 214. Therefore, the reliability of the display device 400B can be improved.

[0335] Transistors 201 and 205 have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as source and drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0336] The transistor structure of the display device of this embodiment is not particularly limited. For example, planar transistors, staggered transistors, inverse staggered transistors, etc., can be used. Furthermore, either a top-gate or bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below the semiconductor layer in which the channel is formed.

[0337] Transistors 201 and 205 are configured in which a semiconductor layer on which a channel is formed is sandwiched between two gates. The transistors may be driven by connecting the two gates and supplying them with the same signal. Alternatively, the threshold voltage of the transistors may be controlled by applying a potential to control the threshold voltage to one of the two gates and a potential to drive the other gate.

[0338] The crystallinity of the semiconductor material used in the transistor is not particularly limited; amorphous semiconductors, single-crystal semiconductors, or semiconductors with crystalline properties other than single crystals (microcrystalline semiconductors, polycrystalline semiconductors, or semiconductors with crystalline regions in part) may be used. Using a single-crystal semiconductor or a semiconductor with crystalline properties is preferable because it can suppress the degradation of transistor characteristics.

[0339] The semiconductor layer of the transistor preferably has a metal oxide (also called an oxide semiconductor). In other words, the display device of this embodiment preferably uses a transistor (hereinafter referred to as an OS transistor) that uses a metal oxide in the channel formation region. Alternatively, the semiconductor layer of the transistor may have silicon. Examples of silicon include amorphous silicon and crystalline silicon (low-temperature polysilicon, single-crystal silicon, etc.).

[0340] The semiconductor layer preferably comprises, for example, indium, M (where M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more selected from aluminum, gallium, yttrium, and tin.

[0341] In particular, it is preferable to use an oxide (also written as IGZO) containing indium (In), gallium (Ga), and zinc (Zn) as the semiconductor layer.

[0342] When the semiconductor layer is an In-M-Zn oxide, it is preferable that the atomic ratio of In in the In-M-Zn oxide is equal to or greater than the atomic ratio of M. Examples of such In-M-Zn oxide atomic ratios of metal elements include compositions where In:M:Zn=1:1:1 or close to it, In:M:Zn=1:1:1.2 or close to it, In:M:Zn=2:1:3 or close to it, In:M:Zn=3:1:2 or close to it, In:M:Zn=4:2:3 or close to it, In:M:Zn=4:2:4.1 or close to it, In:M:Zn=5:1:3 or close to it, In:M:Zn=5:1:6 or close to it, In:M:Zn=5:1:7 or close to it, In:M:Zn=5:1:8 or close to it, In:M:Zn=6:1:6 or close to it, In:M:Zn=5:2:5 or close to it, and so on. Note that "close to it" compositions include a range of ±30% of the desired atomic ratio.

[0343] For example, when describing a composition with an atomic ratio of In:Ga:Zn = 4:2:3 or a similar ratio, it includes cases where, when the atomic ratio of In is 4, the atomic ratio of Ga is between 1 and 3, and the atomic ratio of Zn is between 2 and 4. Also, when describing a composition with an atomic ratio of In:Ga:Zn = 5:1:6 or a similar ratio, it includes cases where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is between 5 and 7. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn = 1:1:1 or a similar ratio, it includes cases where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is greater than 0.1 and 2 or less.

[0344] The transistors in circuit 464 and the transistors in display unit 462 may have the same structure or different structures. The structures of the multiple transistors in circuit 464 may all be the same or there may be two or more different structures. Similarly, the structures of the multiple transistors in display unit 462 may all be the same or there may be two or more different structures.

[0345] A connection portion 204 is provided in the region of substrate 451 where substrate 452 does not overlap. At the connection portion 204, wiring 465 is electrically connected to FPC 472 via conductive layer 466 and connection layer 242. The conductive layer 466 is shown as an example of a laminated structure consisting of a conductive film obtained by processing the same conductive film as the pixel electrode and a conductive film obtained by processing the same conductive film as the optical adjustment layer. The conductive layer 466 is exposed on the upper surface of the connection portion 204. This allows the connection portion 204 and FPC 472 to be electrically connected via the connection layer 242.

[0346] It is preferable to provide a light-shielding layer 417 on the surface of the substrate 452 that faces the substrate 451. Various optical components can also be arranged on the outside of the substrate 452. Examples of optical components include polarizing plates, phase difference plates, light diffusion layers (such as diffusion films), anti-reflective layers, and light-collecting films. Furthermore, an antistatic film to suppress the adhesion of dust, a water-repellent film to make it difficult for dirt to adhere, a hard coat film to suppress the occurrence of scratches during use, and an impact-absorbing layer may also be arranged on the outside of the substrate 452.

[0347] By providing a protective layer 416 that covers the light-emitting element, it is possible to suppress the ingress of impurities such as water into the light-emitting element and improve the reliability of the light-emitting element.

[0348] In the region 228 near the edge of the display device 400B, it is preferable that the insulating layer 215 and the protective layer 416 are in contact with each other through an opening in the insulating layer 214. In particular, it is preferable that the inorganic insulating film of the insulating layer 215 and the inorganic insulating film of the protective layer 416 are in contact with each other. This makes it possible to suppress the entry of impurities into the display unit 462 from the outside through the organic insulating film. Therefore, the reliability of the display device 400B can be improved.

[0349] The display device 400B, like the display device 400A shown in Figure 16B, may have a protective layer 416 consisting of a laminated structure of an organic insulating film and an inorganic insulating film. In this case, it is preferable that the edges of the inorganic insulating film extend outward more than the edges of the organic insulating film.

[0350] Substrates 451 and 452 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, etc., respectively. The substrate on the side that extracts light from the light-emitting element should be made of a material that transmits the light. Using flexible materials for substrates 451 and 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used as substrate 451 or substrate 452.

[0351] Substrates 451 and 452 can be made from polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamide-imide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. One or both of substrates 451 and 452 may be made of glass of a thickness sufficient to provide flexibility.

[0352] Furthermore, when a circular polarizing plate is superimposed on a display device, it is preferable to use a substrate with high optical isotropy for the substrate of the display device. A substrate with high optical isotropy has low birefringence (or a small amount of birefringence).

[0353] For substrates with high optical isotropy, the absolute value of the retardation (phase difference) is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0354] Examples of films with high optical isotropy include triacetylcellulose (TAC, also known as cellulose triacetate) film, cycloolefin polymer (COP) film, cycloolefin copolymer (COC) film, and acrylic film.

[0355] Furthermore, when using a film as the substrate, the film may absorb water, potentially causing wrinkles or other shape changes in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferable to use a film with a water absorption rate of 0.1% or less, and even more preferable to use a film with a water absorption rate of 0.01% or less.

[0356] Various types of curing adhesives can be used as the adhesive layer, including UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of these adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. Materials with low moisture permeability, such as epoxy resins, are particularly preferred. Two-component mixed resins may also be used. Adhesive sheets may also be used.

[0357] As the connecting layer 242, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), etc., can be used.

[0358] Materials that can be used for conductive layers such as the gate, source, and drain of transistors, as well as various wirings and electrodes that constitute display devices, include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, as well as alloys mainly composed of these metals. Films containing these materials can be used as single layers or in a multilayer structure.

[0359] Furthermore, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene can be used as the light-transmitting conductive material. Alternatively, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metallic materials, can be used. Alternatively, nitrides of such metallic materials (e.g., titanium nitride) may be used. When using metallic materials or alloy materials (or their nitrides), it is preferable to make them thin enough to be light-transmitting. In addition, a laminated film of the above materials can be used as a conductive layer. For example, using a laminated film of a silver-magnesium alloy and indium tin oxide is preferable because it can enhance conductivity. These can also be used for conductive layers of various wirings and electrodes that constitute a display device, and for conductive layers of light-emitting elements (conductive layers that function as pixel electrodes or common electrodes).

[0360] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxide nitride, silicon nitride, silicon oxide, and aluminum oxide.

[0361] [Display device 400C] Figure 18A shows a cross-sectional view of the display device 400C. The perspective view of the display device 400C is the same as that of the display device 400A (Figure 15). Figure 18A shows examples of cross-sections of the display device 400C when a portion of the area including the FPC 472, a portion of the circuit 464, and a portion of the display unit 462 are cut. In Figure 18A, an example of a cross-section is shown when a portion of the display unit 462, in particular, including the green light-emitting element 430b and the blue light-emitting element 430c, is cut. Note that explanations of parts that are the same as those of the display device 400A may be omitted.

[0362] The display device 400C shown in Figure 18A has transistors 202, 210, light-emitting elements 430b, and 430c between substrates 453 and 454.

[0363] The substrate 454 and the protective layer 416 are bonded together via an adhesive layer 442. The adhesive layer 442 is provided in overlap with the light-emitting elements 430b and 430c, respectively, and a solid encapsulation structure is applied to the display device 400C.

[0364] The substrate 453 and the insulating layer 212 are bonded together by an adhesive layer 455.

[0365] The method for manufacturing the display device 400C involves first bonding a fabrication substrate, on which an insulating layer 212, transistors, light-emitting elements, etc., are provided, to a substrate 454 on which a light-shielding layer 417 is provided, using an adhesive layer 442. Then, the fabrication substrate is peeled off and a substrate 453 is attached to the exposed surface, thereby transferring the components formed on the fabrication substrate to the substrate 453. It is preferable that both the substrate 453 and the substrate 454 are flexible. This increases the flexibility of the display device 400C.

[0366] The insulating layer 212 can be made of an inorganic insulating film that can be used for insulating layer 211, insulating layer 213, and insulating layer 215, respectively.

[0367] The pixel electrode is connected to the conductive layer 222b of the transistor 210 through an opening in the insulating layer 214. The conductive layer 222b is connected to the low-resistance region 231n through openings in the insulating layers 215 and 225. The transistor 210 has the function of controlling the driving of the light-emitting element.

[0368] The pixel electrode 411 is connected to the conductive layer 222b of the transistor 210 through an opening provided in the insulating layer 214.

[0369] The ends of the pixel electrodes 411 are covered by an insulating layer 421 via a hole injection layer 431. The hole injection layer 431 may be provided over the entire surface of the display unit 462, or it may be divided into sub-pixel regions. An emitting layer is provided at the opening of the insulating layer 421, and a layer 435 having an electron transport layer and an electron injection layer is provided on the insulating layer 421, and a counter electrode 418 is provided on the layer 435. The pixel electrodes 411 contain a material that reflects visible light, and the counter electrode 418 contains a material that transmits visible light.

[0370] The light emitted by the light-emitting elements 430b and 430c is emitted towards the substrate 454. It is preferable to use a material with high transmittance to visible light for the substrate 454.

[0371] A connection portion 204 is provided in the region of substrate 453 that does not overlap with substrate 454. At the connection portion 204, wiring 465 is electrically connected to FPC 472 via conductive layer 466 and connection layer 242. The conductive layer 466 can be obtained by processing the same conductive film as the pixel electrode. This allows the connection portion 204 and FPC 472 to be electrically connected via the connection layer 242.

[0372] Transistors 202 and 210 each have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, a semiconductor layer having a channel forming region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 that functions as a gate insulating layer, a conductive layer 223 that functions as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel forming region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel forming region 231i.

[0373] The conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n via openings provided in the insulating layer 215. Of the conductive layer 222a and the conductive layer 222b, one functions as a source and the other functions as a drain.

[0374] Figure 18A shows an example in which the insulating layer 225 covers the top and sides of the semiconductor layer. The conductive layer 222a and conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 225 and insulating layer 215, respectively.

[0375] On the other hand, in the transistor 209 shown in Figure 18B, the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231, but does not overlap with the low-resistance region 231n. For example, the structure shown in Figure 18B can be fabricated by processing the insulating layer 225 using the conductive layer 223 as a mask. In Figure 18B, an insulating layer 215 is provided covering the insulating layer 225 and the conductive layer 223, and the conductive layers 222a and 222b are connected to the low-resistance region 231n, respectively, through openings in the insulating layer 215. Furthermore, an insulating layer 218 covering the transistor may also be provided.

[0376] [Display device 400D] Figure 19A shows a cross-sectional view of the display device 400D. The perspective view of the display device 400D is the same as that of the display device 400A (Figure 15), and the parts that are the same as those of the display device 400A will not be explained. Specifically, the display device 400D differs from the display device 400A in that it has a hole transport layer 432 on the hole injection layer 431, but the other components are the same as those of the display device 400A, and the explanation of the similar parts will not be explained.

[0377] Since the display device 400D has a hole transport layer 432 on a hole injection layer 431, the edges of the pixel electrodes and optical adjustment layer are covered by the insulating layer 421 via the hole injection layer 431 and the hole transport layer 432. The hole injection layer 431 and the hole transport layer 432 may be provided over the entire surface of the display unit 462, or they may be separated into regions for each sub-pixel.

[0378] The insulating layer 421 may also be a laminated structure of an inorganic insulating film and an organic insulating film. When the insulating layer 421 is a laminated structure of an inorganic insulating film and an organic insulating film, it is preferable that the inorganic insulating film be the lower layer. In one embodiment of the present invention, since the insulating layer 421 is provided on the hole transport layer 432, providing the inorganic insulating film on the hole transport layer 432 side makes it possible to suppress adverse effects on the hole transport layer 432 that are a concern when an organic solvent is used to form the organic insulating film.

[0379] Figure 19B shows an example where the protective layer 416 has a three-layer structure. To reiterate, the display device 400D differs from the display device 400A in that it has a hole transport layer 432 on top of the hole injection layer 431, while the other components are the same as those of the display device 400A, and the explanation of the similar parts will be omitted.

[0380] [Display device 400E] Figure 20 shows a cross-sectional view of the display device 400E. The perspective view of the display device 400E is the same as that of the display device 400A (Figure 15), and the parts that are the same as those of the display device 400A will not be explained. Specifically, the display device 400D differs from the display device 400A in that it has a hole transport layer 432 on the hole injection layer 431, but the other components are the same as those of the display device 400A, and the explanation of the similar parts will not be explained.

[0381] Furthermore, the display device 400E differs from the display device 400B in that it has a hole transport layer 432 on the hole injection layer 431, while the other components are the same as those of the display device 400B, and a description of the similar parts will be omitted.

[0382] Since the display device 400E has a hole transport layer 432 on a hole injection layer 431, the ends of the pixel electrodes are covered by the insulating layer 421 via the hole injection layer 431 and the hole transport layer 432. The hole injection layer 431 and the hole transport layer 432 may be provided over the entire surface of the display unit 462, or they may be separated into regions for each sub-pixel.

[0383] The insulating layer 421 may also be a laminated structure of an inorganic insulating film and an organic insulating film. When the insulating layer 421 is a laminated structure of an inorganic insulating film and an organic insulating film, it is preferable that the inorganic insulating film be the lower layer. In one embodiment of the present invention, since the insulating layer 421 is provided on the hole transport layer 432, providing the inorganic insulating film on the hole transport layer 432 side makes it possible to suppress adverse effects on the hole transport layer 432 that are a concern when an organic solvent is used to form the organic insulating film.

[0384] [Display device 400F] Figure 21A shows a cross-sectional view of the display device 400F. The perspective view of the display device 400F is the same as that of the display device 400A (Figure 15), and the parts that are the same as those of the display device 400A will not be explained. Specifically, the display device 400D differs from the display device 400A in that it has a hole transport layer 432 on the hole injection layer 431, but the other configurations are the same as those of the display device 400A, and the explanation of the similar parts will not be explained.

[0385] Furthermore, the display device 400F differs from the display device 400C in that it has a hole transport layer 432 on the hole injection layer 431, while the other components are the same as those of the display device 400C, and a description of the similar parts will be omitted.

[0386] Since the display device 400F has a hole transport layer 432 on a hole injection layer 431, the ends of the pixel electrodes 411 are covered by the insulating layer 421 via the hole injection layer 431 and the hole transport layer 432. The hole injection layer 431 and the hole transport layer 432 may be provided over the entire surface of the display unit 462, or they may be separated into regions for each sub-pixel.

[0387] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0388] (Embodiment 5) This embodiment describes metal oxides (also called oxide semiconductors) that can be used in the OS transistor described in the above embodiment.

[0389] The metal oxide preferably contains at least indium or zinc. It is particularly preferable that it contains indium and zinc. In addition, it is preferable that it contains aluminum, gallium, yttrium, tin, etc. It may also contain one or more selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, etc.

[0390] Furthermore, metal oxides can be formed by methods such as sputtering, chemical vapor deposition (CVD) methods including metal-organic chemical vapor deposition (MOCVD), or atomic layer deposition (ALD).

[0391] <Classification of crystal structures> Examples of crystalline structures for oxide semiconductors include amorphous (including completely amorphous), CAAC (c-axis-aligned crystalline), nc (nanocrystalline), CAC (cloud-aligned composite), single crystal, and polycrystal.

[0392] The crystal structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. For example, it can be evaluated using the XRD spectrum obtained by GIXD (Grazing-Incidence XRD) measurement. The GIXD method is also known as the thin-film method or the Seemann-Bohlin method.

[0393] For example, in a quartz glass substrate, the peak shape of the XRD spectrum is nearly symmetrical. On the other hand, in an IGZO film with a crystalline structure, the peak shape of the XRD spectrum is asymmetrical. The asymmetrical shape of the XRD spectrum peak clearly indicates the presence of crystals in the film or substrate. In other words, if the peak shape of the XRD spectrum is not symmetrical, the film or substrate cannot be said to be in an amorphous state.

[0394] Furthermore, the crystalline structure of a film or substrate can be evaluated by the diffraction pattern (also called the nano-beam electron diffraction pattern) observed using nano-beam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, confirming that the quartz glass is in an amorphous state. However, in the diffraction pattern of an IGZO film deposited at room temperature, a spot-like pattern is observed instead of a halo. Therefore, it is presumed that an IGZO film deposited at room temperature is in an intermediate state, neither crystalline nor amorphous, and cannot be concluded to be in an amorphous state.

[0395] <<Oxide semiconductor structure>> It should be noted that oxide semiconductors may be classified differently from those described above when considering their structure. For example, oxide semiconductors can be divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the aforementioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors also include polycrystalline oxide semiconductors, pseudo-amorphous oxide semiconductors (a-like OS), and amorphous oxide semiconductors.

[0396] Here, we will explain the details of the CAAC-OS, nc-OS, and a-like OS mentioned above.

[0397] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, the c-axis of which is oriented in a specific direction. This specific direction is the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If we consider the atomic arrangement as a lattice arrangement, then a crystalline region is also a region with a aligned lattice arrangement. Furthermore, CAAC-OS has regions where multiple crystalline regions are connected in the ab-plane direction, and these regions may exhibit distortion. Distortion refers to a point in the connected region where the orientation of the lattice arrangement changes between a region with a aligned lattice arrangement and another region with a aligned lattice arrangement. In short, CAAC-OS is an oxide semiconductor that is c-axis oriented and does not exhibit clear orientation in the ab-plane direction.

[0398] Each of the multiple crystalline regions described above is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of a single minute crystal, the maximum diameter of that crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of that crystalline region may be around several tens of nanometers.

[0399] Furthermore, in In-M-Zn oxides (where element M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), CAAC-OS tends to have a layered crystalline structure (also called a layered structure) consisting of layers containing indium (In) and oxygen (hereinafter referred to as the In layer) and layers containing element M, zinc (Zn), and oxygen (hereinafter referred to as the (M,Zn) layer). Note that indium and element M are mutually substitutable. Therefore, the (M,Zn) layer may contain indium. Also, the In layer may contain element M. Also, the In layer may contain Zn. This layered structure can be observed, for example, as a lattice image in high-resolution TEM (Transmission Electron Microscope) images.

[0400] When structural analysis of a CAAC-OS film is performed using an XRD instrument, for example, out-of-plane XRD measurements using θ / 2θ scanning show a peak indicating c-axis orientation at 2θ = 31° or nearby. Note that the position of the c-axis orientation peak (value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

[0401] Furthermore, for example, multiple bright spots are observed in the electron diffraction pattern of a CAAC-OS film. These spots are observed at point-symmetric positions with respect to the incident electron beam spot (also called the direct spot) that passed through the sample.

[0402] When the crystal region is observed from the specific direction described above, the lattice arrangement within that crystal region is based on a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the strain may have lattice arrangements such as pentagons or heptagons. Moreover, in CAAC-OS, clear grain boundaries cannot be observed even near the strain. In other words, it can be seen that the formation of grain boundaries is suppressed by the strain in the lattice arrangement. This is thought to be because CAAC-OS can tolerate strain due to factors such as the non-dense arrangement of oxygen atoms in the ab-plane direction and the change in interatomic bond distances due to the substitution of metal atoms.

[0403] A crystal structure in which clear grain boundaries are observed is called a polycrystal. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in transistor on-current and field-effect mobility. Therefore, CAAC-OS, in which clear grain boundaries are not observed, is one of the crystalline oxides with a suitable crystal structure for the semiconductor layer of a transistor. In addition, a structure containing Zn is preferred for the composition of CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are preferred because they suppress the generation of grain boundaries more than In oxide.

[0404] CAAC-OS is an oxide semiconductor with high crystallinity and no clearly defined grain boundaries. Therefore, CAAC-OS is less susceptible to the decrease in electron mobility caused by grain boundaries. Furthermore, since the crystallinity of oxide semiconductors can decrease due to the inclusion of impurities and the generation of defects, CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Consequently, oxide semiconductors containing CAAC-OS have stable physical properties. Therefore, oxide semiconductors containing CAAC-OS are heat resistant and highly reliable. In addition, CAAC-OS is stable even at high temperatures (so-called thermal budget) during the manufacturing process. Therefore, using CAAC-OS in OS transistors allows for greater flexibility in the manufacturing process.

[0405] [nc-OS] nc-OS exhibits periodicity in atomic arrangement in minute regions (e.g., regions between 1 nm and 10 nm, particularly between 1 nm and 3 nm). In other words, nc-OS contains minute crystals. These minute crystals are also called nanocrystals because their size is, for example, between 1 nm and 10 nm, particularly between 1 nm and 3 nm. Furthermore, nc-OS shows no regularity in crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Consequently, depending on the analytical method, nc-OS may be indistinguishable from a-like OS or amorphous oxide semiconductors. For example, when structural analysis of an nc-OS film is performed using an XRD instrument, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Also, when electron diffraction (also called limited-field electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter larger than that of the nanocrystals (e.g., 50 nm or larger), a diffraction pattern resembling a halo pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystal (for example, 1 nm to 30 nm), an electron diffraction pattern may be obtained in which multiple spots are observed within a ring-shaped region centered on a direct spot.

[0406] [a-like OS] a-like OS is an oxide semiconductor having a structure between nc-OS and amorphous oxide semiconductors. a-like OS has porous or low-density regions. That is, a-like OS has lower crystallinity compared to nc-OS and CAAC-OS. Also, a-like OS has a higher hydrogen concentration in the film compared to nc-OS and CAAC-OS.

[0407] <<Oxide Semiconductor Composition>> Next, we will explain the details of CAC-OS mentioned above. Note that CAC-OS refers to the material composition.

[0408] [CAC-OS] CAC-OS is a material composition in which, for example, the elements constituting the metal oxide are unevenly distributed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size. In the following, a state in which one or more metal elements are unevenly distributed in a metal oxide, and the regions containing these metal elements are mixed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size, is also referred to as a mosaic or patchy state.

[0409] Furthermore, CAC-OS is a composite metal oxide having a mosaic-like structure formed by the separation of the material into a first region and a second region, with the first region distributed within the film (hereinafter also referred to as a cloud-like structure). In other words, CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0410] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in In-Ga-Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS of In-Ga-Zn oxide, the first region is the region where [In] is greater than the [In] in the composition of the CAC-OS film. The second region is the region where [Ga] is greater than the [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is the region where [In] is greater than the [In] in the second region, and [Ga] is smaller than the [Ga] in the second region. The second region is the region where [Ga] is greater than the [Ga] in the first region, and [In] is smaller than the [In] in the first region.

[0411] Specifically, the first region described above is a region whose main components are indium oxide, indium zinc oxide, etc. The second region described above is a region whose main components are gallium oxide, gallium zinc oxide, etc. In other words, the first region can be rephrased as a region whose main component is In. Similarly, the second region can be rephrased as a region whose main component is Ga.

[0412] Furthermore, a clear boundary may not be observed between the first region and the second region described above.

[0413] Furthermore, CAC-OS in In-Ga-Zn oxide refers to a material composition containing In, Ga, Zn, and O, in which regions with Ga as the main component and regions with In as the main component are arranged in a mosaic-like manner, with these regions existing randomly. Therefore, it is presumed that CAC-OS has a structure in which metal elements are unevenly distributed.

[0414] CAC-OS can be formed, for example, by sputtering under conditions where the substrate is not heated. When forming CAC-OS by sputtering, one or more gases selected from inert gases (typically argon), oxygen gas, and nitrogen gas may be used as the film-forming gas. Furthermore, it is preferable that the ratio of the oxygen gas flow rate to the total flow rate of the film-forming gas during film formation be as low as possible. For example, it is preferable that the ratio of the oxygen gas flow rate to the total flow rate of the film-forming gas during film formation be 0% or more and less than 30%, preferably 0% or more and 10% or less.

[0415] Furthermore, for example, in the case of CAC-OS in In-Ga-Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) confirms that it has a structure in which regions mainly composed of In (first region) and regions mainly composed of Ga (second region) are unevenly distributed and mixed.

[0416] Here, the first region is a region with higher conductivity compared to the second region. In other words, the conductivity of the metal oxide is exhibited when carriers flow through the first region. Therefore, a high field-effect mobility (μ) can be achieved when the first region is distributed in a cloud-like manner within the metal oxide.

[0417] On the other hand, the second region is a region with higher insulating properties compared to the first region. In other words, the distribution of the second region within the metal oxide can suppress leakage current.

[0418] Therefore, when CAC-OS is used in a transistor, the conductivity due to the first region and the insulation due to the second region work complementaryly to give CAC-OS a switching function (on / off function). In other words, CAC-OS has conductive function in part of the material, insulating function in part of the material, and semiconductor function as a whole. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), and good switching operation can be achieved.

[0419] Furthermore, transistors using CAC-OS offer high reliability. Therefore, CAC-OS is ideal for various semiconductor devices, including display devices.

[0420] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention may include two or more of the following: amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

[0421] <Transistors containing oxide semiconductors> Next, we will explain the case where the above oxide semiconductor is used in a transistor.

[0422] By using the above-mentioned oxide semiconductor in transistors, it is possible to realize transistors with high field-effect mobility. Furthermore, it is possible to realize highly reliable transistors.

[0423] It is preferable to use an oxide semiconductor with a low carrier concentration for the transistor. For example, the carrier concentration of an oxide semiconductor is 1 × 10⁻⁶. 17 cm -3 The following is preferably 1 × 10 15 cm -3 More preferably 1 × 10 13 cm -3More preferably 1 × 10 11 cm -3 More preferably 1 × 10 10 cm -3 It is less than 1 × 10 -9 cm -3 This concludes the explanation. Furthermore, when lowering the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film should be lowered to reduce the defect level density. In this specification, a low impurity concentration and low defect level density are referred to as high-purity intrinsic or substantially high-purity intrinsic. Note that oxide semiconductors with low carrier concentrations are sometimes referred to as high-purity intrinsic or substantially high-purity intrinsic oxide semiconductors.

[0424] Furthermore, oxide semiconductor films that are highly intrinsic or substantially highly intrinsic may have a low trap level density due to their low defect level density.

[0425] Furthermore, charges trapped in the trap levels of oxide semiconductors can take a long time to disappear, sometimes behaving like fixed charges. Therefore, transistors in which channel formation regions are formed in oxide semiconductors with a high trap level density may exhibit unstable electrical properties.

[0426] Therefore, reducing the impurity concentration in the oxide semiconductor is effective in stabilizing the electrical characteristics of the transistor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in adjacent films. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0427] <Impurities> Here, we will explain the effects of various impurities in oxide semiconductors.

[0428] In oxide semiconductors, the presence of silicon or carbon, which are Group 14 elements, leads to the formation of defect levels in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon near the interface with the oxide semiconductor (concentration obtained by secondary ion mass spectrometry (SIMS)) are compared by 2 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 17 atoms / cm 3 The following applies:

[0429] Furthermore, if an oxide semiconductor contains alkali metals or alkaline earth metals, it may form defect levels and generate carriers. Therefore, transistors using oxide semiconductors containing alkali metals or alkaline earth metals tend to exhibit normally-on characteristics. For this reason, the concentration of alkali metals or alkaline earth metals in the oxide semiconductor obtained by SIMS should be set to 1 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 16 atoms / cm 3 Do the following:

[0430] Furthermore, in oxide semiconductors, the presence of nitrogen generates electrons, which act as carriers, increasing the carrier concentration and making it easier for the semiconductor to become n-type. As a result, transistors using oxide semiconductors containing nitrogen tend to exhibit normally-on characteristics. Alternatively, the presence of nitrogen in oxide semiconductors can lead to the formation of trap levels. As a result, the electrical properties of the transistor may become unstable. For this reason, the nitrogen concentration in oxide semiconductors obtained by SIMS should be set to 5 × 10⁻⁶. 19 atoms / cm 3 Less than 5 × 10 18 atoms / cm 3 More preferably 1 × 10 18 atoms / cm 3 More preferably 5 × 10 17 atoms / cm 3 Do the following:

[0431] Furthermore, hydrogen contained in oxide semiconductors can react with oxygen bonded to metal atoms to form water, potentially creating oxygen vacancies. Hydrogen can then fill these vacancies, generating electrons, which act as carriers. Additionally, some of the hydrogen can combine with oxygen bonded to metal atoms to generate electrons. Therefore, transistors using oxide semiconductors containing hydrogen tend to exhibit normally-on characteristics. For this reason, it is preferable to reduce the hydrogen content in oxide semiconductors as much as possible. Specifically, in oxide semiconductors, the hydrogen concentration obtained by SIMS should be 1 × 10⁻⁶. 20 atoms / cm 3 Less than 1 × 10 19 atoms / cm 3 Less than 5x10 18 atoms / cm 3 Less than 1 × 10 18 atoms / cm 3 Make it less than.

[0432] By using an oxide semiconductor with sufficiently reduced impurities in the channel formation region of a transistor, stable electrical characteristics can be provided.

[0433] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0434] (Embodiment 6) In this embodiment, an electronic device according to one aspect of the present invention will be described with reference to Figures 22 to 25.

[0435] The electronic device of this embodiment has a display device according to one aspect of the present invention. The display device according to one aspect of the present invention is easily made high-definition, high-resolution, and large-scale. Therefore, the display device according to one aspect of the present invention can be used in the display units of various electronic devices.

[0436] Furthermore, since the display device according to one aspect of the present invention can be manufactured at a low cost, the manufacturing cost of electronic devices can be reduced.

[0437] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as other electronic devices with relatively large screens, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, and audio playback devices.

[0438] In particular, a display device according to one aspect of the present invention can be used suitably in electronic devices having a relatively small display area because it can increase resolution. Examples of such electronic devices include information terminals (wearable devices) such as wristwatches and bracelets, as well as wearable devices that can be worn on the head, such as VR devices such as head-mounted displays and AR devices such as glasses. Wearable devices also include devices for SR and MR.

[0439] A display device according to one aspect of the present invention preferably has an extremely high resolution such as HD (1280 x 720 pixels), FHD (1920 x 1080 pixels), WQHD (2560 x 1440 pixels), WQXGA (2560 x 1600 pixels), 4K2K (3840 x 2160 pixels), or 8K4K (7680 x 4320 pixels). In particular, a resolution of 4K2K, 8K4K, or higher is preferred. Furthermore, the pixel density (resolution) of the display device according to one aspect of the present invention is preferably 300 ppi or more, more preferably 500 ppi or more, more preferably 1000 ppi or more, more preferably 2000 ppi or more, more preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 7000 ppi or more. By using display devices with such high resolution or detail, it becomes possible to enhance the sense of presence and depth in personal electronic devices such as portable or home-use devices.

[0440] The electronic device of this embodiment can be incorporated along the curved surfaces of the interior or exterior walls of a house or building, or the interior or exterior of an automobile.

[0441] The electronic device in this embodiment may have an antenna. By receiving signals with the antenna, the display unit can display images and information. Furthermore, if the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0442] The electronic device of this embodiment may have sensors (including those with the function of detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation).

[0443] The electronic device of this embodiment can have a variety of functions. For example, it can have a function to display various information (still images, videos, text images, etc.) on the display unit, a touch panel function, a function to display a calendar, date or time, a function to execute various software (programs), a wireless communication function, a function to read programs or data recorded on a recording medium, and so on.

[0444] The electronic device 6500 shown in Figure 22A is a portable information terminal that can be used as a smartphone.

[0445] The electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508, etc. The display unit 6502 has a touch panel function.

[0446] A display device according to one aspect of the present invention can be applied to the display unit 6502.

[0447] Figure 22B is a schematic cross-sectional view of the housing 6501, including the end on the microphone 6506 side.

[0448] A light-transmitting protective member 6510 is provided on the display side of the housing 6501, and the display panel 6511, optical member 6512, touch sensor panel 6513, printed circuit board 6517, battery 6518, etc. are arranged in the space enclosed by the housing 6501 and the protective member 6510.

[0449] The protective member 6510 is fixed to the display panel 6511, the optical member 6512, and the touch sensor panel 6513 by an adhesive layer (not shown).

[0450] In the area outside the display unit 6502, a portion of the display panel 6511 is folded back, and the FPC 6515 is connected to this folded portion. IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to terminals provided on the printed circuit board 6517.

[0451] A flexible display (a display device with flexibility) according to one embodiment of the present invention can be applied to the display panel 6511. As a result, an extremely lightweight electronic device can be realized. Furthermore, because the display panel 6511 is extremely thin, a large-capacity battery 6518 can be installed while keeping the thickness of the electronic device low. In addition, by folding back a part of the display panel 6511 and placing the connection part with the FPC 6515 on the back of the pixel area, an electronic device with a narrow bezel can be realized.

[0452] Figure 23A shows an example of a television system. The television system 7100 has a display unit 7000 incorporated into a housing 7101. Here, the housing 7101 is shown supported by a stand 7103.

[0453] A display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0454] The television device 7100 shown in Figure 23A can be operated using the operation switches on the housing 7101 and a separate remote control unit 7111. Alternatively, the display unit 7000 may be equipped with a touch sensor, and the television device 7100 can be operated by touching the display unit 7000 with a finger or the like. The remote control unit 7111 may have a display unit that displays information output from the remote control unit 7111. Channels and volume can be controlled and the image displayed on the display unit 7000 can be controlled using the operation keys or touch panel on the remote control unit 7111.

[0455] The television system 7100 is configured to include a receiver and a modem. The receiver can receive general television broadcasts. Furthermore, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0456] Figure 23B shows an example of a notebook personal computer. The notebook personal computer 7200 has a casing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, etc. A display unit 7000 is incorporated into the casing 7211.

[0457] A display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0458] Figures 23C and 23D show examples of digital signage.

[0459] The digital signage 7300 shown in Figure 23C comprises a housing 7301, a display unit 7000, and a speaker 7303, etc. Furthermore, it may include LED lamps, operation keys (including a power switch or operation switch), connection terminals, various sensors, a microphone, etc.

[0460] Figure 23D shows a digital signage 7400 mounted on a cylindrical column 7401. The digital signage 7400 has a display unit 7000 that is provided along the curved surface of the column 7401.

[0461] In Figures 23C and 23D, a display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0462] The larger the display area 7000, the more information can be provided at once. Furthermore, a larger display area 7000 is more eye-catching, which can, for example, enhance the effectiveness of advertising.

[0463] Applying a touch panel to the display unit 7000 is preferable because it not only allows images or videos to be displayed on the display unit 7000, but also enables intuitive operation by the user. Furthermore, when used for purposes such as providing route information or traffic information, intuitive operation can enhance usability.

[0464] Furthermore, as shown in Figures 23C and 23D, it is preferable that the digital signage 7300 or digital signage 7400 can be linked wirelessly with an information terminal 7311 or information terminal 7411 such as a smartphone owned by the user. For example, the advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or information terminal 7411. Also, the display on the display unit 7000 can be switched by operating the information terminal 7311 or information terminal 7411.

[0465] Furthermore, the digital signage 7300 or digital signage 7400 can be used to run games using the screen of the information terminal 7311 or information terminal 7411 as the control device (controller). This allows a large number of users to participate in and enjoy the game simultaneously.

[0466] Figure 24A shows the external appearance of the camera 8000 with the viewfinder 8100 attached.

[0467] The camera 8000 includes a housing 8001, a display unit 8002, operation buttons 8003, a shutter button 8004, etc. A detachable lens 8006 is also attached to the camera 8000. The lens 8006 and the housing of the camera 8000 may be integrated into a single unit.

[0468] Camera 8000 can take an image by pressing the shutter button 8004 or by touching the display unit 8002, which functions as a touch panel.

[0469] The housing 8001 has a mount with electrodes, and in addition to the viewfinder 8100, a strobe device and the like can be connected to it.

[0470] The viewfinder 8100 includes a housing 8101, a display unit 8102, buttons 8103, etc.

[0471] The housing 8101 is attached to the camera 8000 by a mount that engages with the camera 8000's mount. The viewfinder 8100 can display images and other data received from the camera 8000 on the display unit 8102.

[0472] Button 8103 functions as a power button, etc.

[0473] A display device according to one embodiment of the present invention can be applied to the display unit 8002 of the camera 8000 and the display unit 8102 of the viewfinder 8100. The camera 8000 may also have a built-in viewfinder.

[0474] Figure 24B shows the external appearance of the head-mounted display 8200.

[0475] The head-mounted display 8200 includes a mounting section 8201, lenses 8202, a main unit 8203, a display unit 8204, a cable 8205, etc. The mounting section 8201 also has a built-in battery 8206.

[0476] Cable 8205 supplies power from battery 8206 to main unit 8203. Main unit 8203 is equipped with a wireless receiver and can display received video information on display unit 8204. In addition, main unit 8203 is equipped with a camera and can use information about the user's eyeball or eyelid movements as an input means.

[0477] Furthermore, the attachment unit 8201 may be provided with multiple electrodes at a position that touches the user, capable of detecting the current flowing in accordance with the user's eye movements, and may have a function to recognize the user's gaze. It may also have a function to monitor the user's pulse rate based on the current flowing through the electrodes. In addition, the attachment unit 8201 may have various sensors such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may have a function to display the user's biometric information on the display unit 8204, or a function to change the image displayed on the display unit 8204 in accordance with the user's head movements.

[0478] A display device according to one aspect of the present invention can be applied to the display unit 8204.

[0479] Figures 24C to 24E show the external appearance of the head-mounted display 8300. The head-mounted display 8300 includes a housing 8301, a display unit 8302, a band-shaped fixing device 8304, and a pair of lenses 8305.

[0480] The user can view the display on the display unit 8302 through the lens 8305. It is preferable to position the display unit 8302 in a curved shape, as this allows the user to experience a greater sense of presence. Furthermore, by viewing different images displayed in different areas of the display unit 8302 through the lens 8305, three-dimensional display using parallax can be performed. Note that the configuration is not limited to a single display unit 8302; two display units 8302 may be provided, with one display unit for each of the user's eyes.

[0481] A display device according to one embodiment of the present invention can be applied to the display unit 8302. The display device according to one embodiment of the present invention can also achieve extremely high resolution. For example, even when the display is magnified and viewed using the lens 8305 as shown in Figure 24E, the pixels are difficult for the user to see. In other words, the display unit 8302 can be used to allow the user to view a highly realistic image.

[0482] Figure 24F shows the external appearance of a goggle-type head-mounted display 8400. The head-mounted display 8400 has a pair of housings 8401, a mounting part 8402, and a cushioning member 8403. A display unit 8404 and a lens 8405 are provided inside each of the pair of housings 8401. By displaying different images on the pair of display units 8404, a three-dimensional display using parallax can be achieved.

[0483] The user can view the display unit 8404 through the lens 8405. The lens 8405 has a focus adjustment mechanism and its position can be adjusted according to the user's eyesight. The display unit 8404 is preferably a square or a horizontally elongated rectangle. This can enhance the sense of realism.

[0484] The mounting portion 8402 is preferably adjustable to the size of the user's face and has plasticity and elasticity to prevent it from slipping off. Furthermore, it is preferable that a part of the mounting portion 8402 has a vibration mechanism that functions as a bone conduction earphone. This eliminates the need for separate audio equipment such as earphones or speakers, allowing users to enjoy video and audio simply by wearing the device. The housing 8401 may also have a function to output audio data via wireless communication.

[0485] The mounting portion 8402 and the cushioning member 8403 are parts that come into contact with the user's face (forehead, cheeks, etc.). By ensuring that the cushioning member 8403 is in close contact with the user's face, light leakage can be prevented, thereby enhancing the sense of immersion. It is preferable to use a soft material for the cushioning member 8403 so that it adheres closely to the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, urethane, and sponge can be used. Furthermore, if the surface of a sponge or similar material is covered with cloth, leather (genuine leather or synthetic leather), gaps are less likely to form between the user's face and the cushioning member 8403, effectively preventing light leakage. In addition, using such materials is preferable because it feels good against the skin and does not make the user feel cold when worn in cold seasons. It is preferable that the components that come into contact with the user's skin, such as the cushioning member 8403 or the mounting portion 8402, are removable, as this makes cleaning or replacement easier.

[0486] The electronic equipment shown in Figures 25A to 25F includes a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or operation switch), connection terminals 9006, sensors 9007 (including functions for detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation), a microphone 9008, etc.

[0487] The electronic devices shown in Figures 25A to 25F have various functions. For example, they may have functions to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date or time, a function to control processing by various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. However, the functions of electronic devices are not limited to these and can have various functions. Electronic devices may have multiple display units. Furthermore, electronic devices may be equipped with a camera, etc., and have functions to capture still images or videos and save them to a recording medium (external or built into the camera), a function to display the captured images on a display unit, etc.

[0488] A display device according to one embodiment of the present invention can be applied to the display unit 9001.

[0489] Details of the electronic equipment shown in Figures 25A to 25F will be explained below.

[0490] Figure 25A is a perspective view showing a personal digital assistant (PDA) 9101. The PDA 9101 can be used, for example, as a smartphone. The PDA 9101 may also be equipped with a speaker 9003, connection terminals 9006, sensors 9007, etc. The PDA 9101 can also display text and image information on multiple surfaces. Figure 25A shows an example where three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on other surfaces of the display unit 9001. Examples of information 9051 include notifications of incoming emails, SNS messages, and phone calls, the subject of emails and SNS messages, the sender's name, date and time, battery level, and antenna signal strength. Alternatively, icons 9050 or the like may be displayed in the location where the information 9051 is displayed.

[0491] Figure 25B is a perspective view showing the personal digital assistant (PDA) 9102. The PDA 9102 has the function of displaying information on three or more sides of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different sides. For example, a user can check information 9053, which is displayed in a position that can be observed from above the PDA 9102, while the PDA 9102 is stored in the breast pocket of their clothing. The user can check the display without taking the PDA 9102 out of their pocket and decide, for example, whether or not to answer a call.

[0492] Figure 25C is a perspective view showing a wristwatch-type personal information terminal 9200. The personal information terminal 9200 can be used, for example, as a smartwatch (registered trademark). The display unit 9001 has a curved display surface, allowing it to display information along the curved surface. The personal information terminal 9200 can also be used for hands-free calls by communicating with, for example, a wireless communication headset. Furthermore, the personal information terminal 9200 can transmit data to other information terminals and be charged via a connection terminal 9006. Charging may be performed by wireless power supply.

[0493] Figures 25D to 25F are perspective views showing a foldable portable information terminal 9201. Figure 25D shows the portable information terminal 9201 in an unfolded state, Figure 25F shows it in a folded state, and Figure 25E shows a perspective view of the state in between, transitioning from one of Figures 25D or 25F to the other. The portable information terminal 9201 offers excellent portability in its folded state and excellent readability of the display due to its seamless, wide display area in its unfolded state. The display unit 9001 of the portable information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display unit 9001 can be bent with a radius of curvature of 0.1 mm to 150 mm.

[0494] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part. [Explanation of Symbols]

[0495] AB: line, AL: wiring, CD: line, CL: wiring, GL: wiring, IC: display device, SL: wiring, 20: light-emitting element, 100: pixel area, 101: insulating film, 102: anode, 104: hole injection layer, 105: hole transport layer, 110x: first area, 110y: second area, 110: partition, 115b: light-emitting layer, 115g: light-emitting layer, 115r: light-emitting layer, 118b: third liquid reservoir, 118g: second liquid reservoir, 118r: first liquid reservoir, 119: nozzle, 201: transistor, 202: transistor, 204: connector, 205: transistor, 209: transistor, 210: Transistor, 211: Insulating layer, 212: Insulating layer, 213: Insulating layer, 214: Insulating layer, 215: Insulating layer, 218: Insulating layer, 221: Conductive layer, 222a: Conductive layer, 222b: Conductive layer, 223: Conductive layer, 225: Insulating layer, 228: Region, 231i: Channel formation region, 231n: Low resistance region, 231: Semiconductor layer, 242: Connecting layer, 400A: Display device, 400B: Display device, 400C: Display device, 400D: Display device, 400E: Display device, 400F: Display device, 411a: Pixel electrode, 411b: Pixel electrode, 411c: Pixel electrode, 411: Pixel electrode, 4 16a: Inorganic insulating layer, 416b: Organic insulating layer, 416c: Inorganic insulating layer, 416: Protective layer, 417: Light-shielding layer, 418: Counter electrode, 421: Insulating layer, 426a: Optical adjustment layer, 426b: Optical adjustment layer, 426c: Optical adjustment layer, 430a: Light-emitting element, 430b: Light-emitting element, 430c: Light-emitting element, 431: Hole injection layer, 432: Hole transport layer, 435: Layer, 442: Adhesive layer, 443: Space, 451: Substrate, 452: Substrate, 453: Substrate, 454: Substrate, 455: Adhesive layer, 462: Display section, 464: Circuit, 465: Wiring, 466: Conductive layer, 472: FPC, 473: IC , 672: lower electrode, 686a: first light-emitting unit, 686b: second light-emitting unit, 686: light-emitting unit, 688: upper electrode, 690a: intermediate layer, 690b: intermediate layer, 690: intermediate layer, 4411: first light-emitting layer, 4412: second light-emitting layer, 4413: third light-emitting layer, 4420: layer, 4430: layer, 6500: electronic device, 6501: housing, 6502: display unit, 6503: power button, 6504: button, 6505: speaker, 6506: microphone, 6507: camera, 6508: light source, 6510: protective member, 6511: display panel, 6512: optical member,6513: Touch sensor panel, 6515: FPC, 6516: IC, 6517: Printed circuit board, 6518: Battery, 7000: Display unit, 7100: Television equipment, 7101: Enclosure, 7103: Stand, 7111: Remote control unit, 7200: Notebook personal computer, 7211: Enclosure, 7212: Keyboard, 7213: Pointing device, 7214: External connection port, 7300: Digital signage, 7301: Enclosure, 7303: Speaker, 7311: Information terminal, 7400: Digital signage, 7401: Pillar, 7411: Information terminal, 8000: Camera, 8001: Enclosure, 8002: Display unit, 8003: Operation buttons, 8004: Shutter button, 8006: Lens, 8100: Viewfinder, 8101: Enclosure, 8102: Display unit, 8103: Button, 820 0: Head-mounted display, 8201: Mounting part, 8202: Lens, 8203: Main unit, 8204: Display unit, 8205: Cable, 8206: Battery, 8300: Head-mounted display, 8301: Housing, 8302: Display unit, 8304: Fixing device, 8305: Lens, 8400: Head-mounted display, 8401: Housing, 8402: Mounting part, 8403: Cushioning material, 8404: Display Part, 8405: Lens, 9000: Housing, 9001: Display unit, 9003: Speaker, 9005: Operation keys, 9006: Connection terminal, 9007: Sensor, 9008: Microphone, 9050: Icon, 9051: Information, 9052: Information, 9053: Information, 9054: Information, 9055: Hinge, 9101: Personal digital assistant, 9102: Personal digital assistant, 9200: Personal digital assistant, 9201: Personal digital assistant,

Claims

[Claim 1] The first anode and, A second anode adjacent to the first anode in the X direction, A third anode adjacent to the first anode in the Y direction, A hole injection layer is provided across the first to third anodes, A partition wall provided on the hole injection layer, A first light-emitting layer located at the first opening of the partition wall and overlapping with the first anode, A second light-emitting layer located at the second opening of the partition wall and overlapping with the second anode, A third light-emitting layer located at the third opening of the partition wall and overlapping with the third anode, A cathode is provided across the first to third light-emitting layers, The aforementioned partition wall is In a top view, it has a first region located between the first anode and the third anode and extending in the X direction, a second region located between the first anode and the second anode and extending in the Y direction, and an intersection of the first region and the second region. In a cross-sectional view, the height in the first region is greater than the height in the second region, and the height at the intersection is greater than the height in the first region. The partition wall has a laminated structure in the first region. Display device.

Images