Display device and manufacturing method thereof

Abstract

Provided is a display device that, as a light emitting element, achieves a reduction in liquid pool near a partition wall when a light emitting layer is formed by a wet process. This display device comprises a first anode, a second anode adjacent to the first anode in an X direction, a third anode adjacent to the first anode in a Y direction, a hole injection layer provided 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. The partition wall has a first region located between the first anode and the third anode 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 when viewed from above, and the height thereof in the first region is larger than that in the second region when viewed in cross section.

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a display device and a manufacturing method thereof.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. More specific technical fields of one embodiment of the present invention disclosed in this specification and the like include semiconductor devices, display devices, light-emitting devices, power storage devices, and memory devices, and also include driving methods or manufacturing methods thereof. [Background technology]

[0003] One method for manufacturing a display device with organic EL is the inkjet method, in which a solution containing a light-emitting material is dropped and the solvent is evaporated from the solution to form a light-emitting layer.A method is known in which a light-emitting layer is formed by the inkjet method, eliminating the need for a baking process for the solution (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-87465 Summary of the Invention [Problem to be solved by the invention]

[0005] Figure 3(A) of the above-mentioned Patent Document 1 shows how the solution is dropped into the areas where each pixel is divided by an insulator, and shows the liquid puddles immediately after dropping. Because the solvent evaporates in these liquid puddles, the above-mentioned Patent Document 1 discloses that the use of the coating process makes it possible to eliminate the need for a baking process.

[0006] However, it is difficult to eliminate the firing step, and firing in a reduced-pressure atmosphere leaves puddles near the insulator, i.e., the partition wall. These puddles cause current to concentrate in the center of the light-emitting area, resulting in non-uniform current density. Therefore, the inventors considered it important to suppress these puddles in order to provide high-resolution display devices.

[0007] In view of the above, one embodiment of the present invention provides a display device formed by a wet method such as an ink-jet method, in which liquid pools are reduced, and a manufacturing method thereof.

[0008] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these will become apparent from the description of the specification, drawings, claims, etc. (hereinafter referred to as the present specification, etc.), and problems other than these can be extracted from the description of the present specification, etc. [Means for solving the problem]

[0009] In view of the above problems, one embodiment of the present invention provides a light-emitting device including: 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 across the first anode, the second anode, and the third anode; a partition wall provided on the hole-injection layer; a first light-emitting layer located in a first opening of the partition wall and overlapping with the first anode; a second light-emitting layer located in a second opening of the partition wall and overlapping with the second anode; a third light-emitting layer located in a portion of the first light-emitting layer and overlapping with the third anode, and a cathode provided across the first to third light-emitting layers, wherein the partition 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 the height of the first region is greater than the height of the second region in a cross-sectional view.

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

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

[0012] Another embodiment of the present invention relates to a semiconductor device including: 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 across the first to third anodes; a partition wall provided on the hole-injection layer; a first light-emitting layer located in a first opening of the partition wall and overlapping with the first anode; a second light-emitting layer located in a second opening of the partition wall and overlapping with the second anode; and a third anode located in a third opening of the partition wall. a third light-emitting layer overlapping the first light-emitting layer and a cathode provided across the first to third light-emitting layers, wherein the partition has a first region located between the first anode and the third anode and extending in an X direction in a top view, and a second region located between the first anode and the second anode and extending in a Y direction, the height of the second region being greater than the height of the first region in a cross-sectional view, and the partition has a stacked structure in the second region.

[0013] In one embodiment of the present invention, the partition wall having a stacked structure preferably includes a first partition wall including an inorganic material and a second partition wall including an organic material located over 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, the first to third anodes preferably have tapered ends.

[0017] Another embodiment of the present invention is a method for manufacturing a semiconductor device comprising: 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 anode, the second anode, and the third anode; forming a partition wall on the hole injection layer, the partition wall having a first opening overlapping with the first anode, a second opening overlapping with the second anode, and a third opening overlapping with the third anode; and forming a first light-emitting layer located in the first opening, a second light-emitting layer located in the second opening, or a third light-emitting layer located in the third opening, by an ink-jet method. and forming a cathode across the first to third light-emitting layers, wherein the partition 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, the height of the first region being greater than the height of the second region in a cross-sectional view, and either the first light-emitting layer or the third light-emitting layer is formed by an inkjet method while moving along the first region.

[0018] Another embodiment of the present invention is a method for manufacturing a semiconductor device comprising: 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 anode, the second anode, and the third anode; forming a partition wall on the hole injection layer, the partition wall having a first opening overlapping with the first anode, a second opening overlapping with the second anode, and a third opening overlapping with the third anode; and forming a first light-emitting layer located in the first opening, a second light-emitting layer located in the second opening, or a third light-emitting layer located in the third opening, by an ink-jet method. and forming a cathode across the first to third light-emitting layers, wherein the partition 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 the height of the second region is greater than the height of the first region in a cross-sectional view, and either the first light-emitting layer or the third light-emitting layer is formed by an inkjet method while moving along the second region.

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

[0020] According to one embodiment of the present invention, a display device in which liquid pooling is suppressed and a manufacturing method thereof can be provided.

[0021] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in this specification, etc., and effects other than these can be extracted from the description in this specification, etc. [Brief explanation of the drawings]

[0022] FIG. 1 is a perspective view illustrating a pixel region of one embodiment of the present invention. 2A and 2B are cross-sectional views illustrating a pixel region according to one embodiment of the present invention. 3A to 3C are cross-sectional views illustrating a pixel region of one embodiment of the present invention. 4A to 4C are cross-sectional views illustrating a method for manufacturing a pixel region according to one embodiment of the present invention. FIG. 5 is a perspective view illustrating a pixel region according to one embodiment of the present invention. FIG. 6 is a perspective view illustrating a pixel region according to one embodiment of the present invention. 7A and 7B are cross-sectional views illustrating a pixel region according to one embodiment of the present invention. 8A to 8C are cross-sectional views illustrating a pixel region of one embodiment of the present invention. 9A to 9C are cross-sectional views illustrating a method for manufacturing a pixel region according to one embodiment of the present invention. FIG. 10 is a perspective view illustrating a pixel region according to one embodiment of the present invention. 11A to 11D2 are cross-sectional views illustrating light-emitting elements of embodiments of the present invention. 12A to 12D are circuit diagrams illustrating pixel circuits of one embodiment of the present invention. 13A to 13D are circuit diagrams illustrating pixel circuits of one embodiment of the present invention. FIG. 14 illustrates a method for driving a pixel circuit according to one embodiment of the present invention. FIG. 15 is a perspective view showing an example of a display device. 16A and 16B are cross-sectional views showing an example of a display device. FIG. 17 is a cross-sectional view showing an example of a display device. 18A is a cross-sectional view illustrating an example of a display device, and FIG. 18B is a cross-sectional view illustrating an example of a transistor. 19A and 19B are cross-sectional views showing an example of a display device. FIG. 20 is a cross-sectional view showing an example of a display device. 21A is a cross-sectional view showing an example of a display device, and FIG 21B is a cross-sectional view showing an example of a transistor. 22A and 22B are diagrams showing an example of an electronic device. 23A to 23D are diagrams showing an example of an electronic device. 24A to 24F are diagrams showing an example of an electronic device. 25A to 25F are diagrams showing an example of an electronic device. DETAILED DESCRIPTION OF THE INVENTION

[0023] In the drawings attached to this specification, components are classified by function and explained using block diagrams that are independent of each other, but in reality, it is difficult to completely separate components by function, and one component may be involved in multiple functions.

[0024] In this specification and the like, the names of the source and drain of a transistor are interchangeable depending on the polarity of the transistor and the level of the potential applied to each terminal. Generally, in an n-channel transistor, a terminal to which a low potential is applied is called a source, and a terminal to which a high potential is applied is called a drain. In a p-channel transistor, a terminal to which a low potential is applied is called a drain, and a terminal to which a high potential is applied is called a source. For convenience, in this specification and the like, the connection relationship of a transistor may be described assuming that the source and drain are fixed, but in reality, the names of the source and drain are interchangeable depending on the above-mentioned potential relationship.

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

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

[0027] In this specification, "connection" means an electrical connection, and corresponds to a state in which a current, voltage, or potential can be supplied or transmitted. Therefore, a connected state does not necessarily refer to a direct connection, but also includes a state in which a current, voltage, or potential can be supplied or transmitted via a circuit element such as a wiring, resistor, diode, or transistor.

[0028] In this specification, even if components that appear independent on a circuit diagram are connected to each other, in reality, one conductive layer may have the functions of multiple components, for example, when part of a wiring functions as an electrode. In this specification, the term "connection" also includes such cases where one conductive layer has the functions of multiple components.

[0029] In this specification and the like, a transistor may be described using a first electrode and a second electrode. When one of the first electrode and the second electrode is a source electrode, the other is a drain electrode.

[0030] In this specification and the like, 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 an anode, and the other of the pair of electrodes is a cathode. The organic compound layer is a functional layer, one of which is a light-emitting layer. The functional layers form a laminate, and a structure having at least a light-emitting layer is sometimes referred to as a light-emitting unit. Also, in this specification and the like, a light-emitting element is sometimes referred to as a light-emitting device.

[0031] In this specification and the like, a light emitting device that does not use a metal mask or a fine metal mask (FMM) may be referred to as a light emitting device having a metal maskless (MML) structure.

[0032] In this specification, a structure in which light-emitting layers of different colors (for example, red (R), green (G), and blue (B)) are painted separately may be referred to as an SBS (Side By Side) structure. Also, in this specification, a light-emitting element capable of emitting white light may be referred to as a white light-emitting element. Note that a white light-emitting element can be combined with a colored layer (for example, a color filter) to form a full-color display device.

[0033] In this specification, light-emitting elements can be broadly classified into a single structure and a tandem structure. A single structure has one light-emitting unit between a pair of electrodes, and the light-emitting unit has one or more light-emitting layers. In a single structure, white light can be obtained by selecting two or more light-emitting layers such that the light emitted from each of the two or more light-emitting layers has a complementary color relationship. 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 to each other, a configuration in which the light-emitting element as a whole emits white light can be obtained. The same applies to a light-emitting element having three or more light-emitting layers.

[0034] The 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, light from the light-emitting layers of the two or more light-emitting units can be combined to obtain white light emission. The structure for obtaining white light emission is the same as that of the single structure. In the tandem structure, it is preferable to provide an intermediate layer such as a charge generation layer between the multiple light-emitting units.

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

[0036] Next, embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below. In the configuration of the invention described below, the same parts or parts having similar functions will be denoted by the same reference numerals in different drawings, and repeated explanations will be omitted.

[0037] (Embodiment 1) In this embodiment, a display device according to one embodiment of the present invention will be described. The display device includes a light-emitting element, and the light-emitting element includes a hole injection layer including a hole injection material, a hole transport layer including a hole transport material, a light-emitting layer including a light-emitting material, an electron transport layer including an electron transport material, or an electron injection layer including an electron injection material. In one embodiment of the present invention, any of the above layers can be manufactured by a wet process. In this embodiment, a case where a light-emitting layer is manufactured by a wet process will be mainly described.

[0038] A wet method is a method in which a material having a predetermined function is dissolved or dispersed in a solvent to obtain a liquid composition, which is then applied. After application, the composition is solidified or formed into a thin film through a drying or curing process. The liquid composition is sometimes referred to as a solution. Representative wet methods include spin coating, inkjet printing, casting, printing, dispensing, and spraying.

[0039] The display device according to one embodiment of the present invention is characterized by the height of the partition wall, etc. As a display device according to one embodiment of the present invention, a first structural example in which a hole injection layer is located below the partition wall and a second structural example in which a hole injection layer and a hole transport layer are located below the partition wall will be described.

[0040] <Configuration example 1> FIG. 1 shows an example of a perspective view of a display device, FIGS. 2A to 3C show example cross-sectional views of the display device, FIG. 4 shows an example of the preparation of a light-emitting layer, and FIG. 5 shows an example of a perspective view of a display device different from that of FIG.

[0041] As shown in Fig. 1, the display device has a pixel region 100 in which light-emitting elements are provided, as well as a drive circuit region and the like. The pixel region 100 has a plurality of pixels, and each pixel further has a plurality of sub-pixels. A pixel is the smallest unit capable of full-color display, and when full-color display is achieved using red, green, and blue, one of the plurality of sub-pixels can correspond to the light-emitting region of a red light-emitting element, another can correspond to the light-emitting region of a green light-emitting element, and another can correspond to the light-emitting region of a blue light-emitting element, as viewed from above (sometimes referred to as a planar view).

[0042] Although not shown in Fig. 1, each subpixel also includes a transistor electrically connected to each light-emitting element, and the light-emitting element can be controlled using the transistor. A display device having such a structure is called an active matrix display device, and Configuration Example 1, which is an embodiment of the present invention, and the like can be applied to such a display device. Of course, Configuration Example 1, which is an embodiment of the present invention, and the like can also be applied to a passive matrix display device.

[0043] In describing the configuration of the pixel region 100, an X direction and a Y direction intersecting the X direction may be used as shown in Fig. 1. For example, the X direction is the direction along the wiring to which gate signals are supplied, and the Y direction is the direction along the wiring to which source signals are supplied.

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

[0045] <Insulating film 101> As shown in FIG. 1, an insulating film 101 is provided on the transistor. This insulating film serves as a surface on which an anode or the like will be formed later. Therefore, the insulating film 101 is preferably formed using an organic material so that the surface on which the insulating film 101 is formed is flat. The insulating film 101 is preferably formed using an inorganic material so that it functions as a protective film to prevent impurities from entering the transistor. To ensure that the insulating film 101 has flatness and functions as a protective film, it is preferable that the insulating film 101 has a stacked structure including at least a first insulating film containing an inorganic material and a second insulating film containing an organic material located on the first insulating film.

[0046] An organic resin such as a polyimide resin, a polyamide resin, an acrylic resin, a siloxane resin, a silicone resin, an epoxy resin, or a phenol resin may be used as the organic material to form the insulating film 101. Note that a material obtained by adding an impurity element such as lanthanum (La), nitrogen, or zirconium (Zr) to the above materials may also be used.

[0047] The insulating film 101 may be formed using an inorganic material containing one or more of aluminum oxide, magnesium oxide, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, and tantalum oxide. Note that a material obtained by adding an impurity element such as lanthanum (La), nitrogen, or zirconium (Zr) to the above material may also be used.

[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, which enables a wiring layer located below the insulating film (referred to as a lower wiring layer) to be electrically connected to a wiring layer located above the insulating film (referred to as an upper wiring layer). To achieve the electrical connection, the lower wiring layer has a region exposed from the opening, and the upper wiring layer has a region located within the opening in a cross-sectional view.

[0049] A signal, for example, a predetermined potential, is applied to the anode 102 by the transistor. Therefore, the anode 102 is processed so that it is independent for each sub-pixel. Processing to make it independent is sometimes referred to as separation. This processing is also sometimes referred to as patterning. Furthermore, the anode 102 electrically connected to the transistor is sometimes referred to as a pixel electrode.

[0050] The anode 102 is preferably made of a material with a high work function. 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), a silicon-containing indium tin oxide film, an indium oxide film containing 2 to 20 wt % zinc oxide, or a titanium nitride film. The anode 102 may also have a single-layer film such as a chromium film, a tungsten film, a Zn film, an Al film, an Ag film, or a Pt film. The anode 102 may also have a multilayer structure, such as a multilayer structure of a titanium nitride film and a film primarily composed of aluminum, or a three-layer structure of a titanium nitride film, a film primarily composed of aluminum, and another titanium nitride film. The multilayer structure has the advantage of being able to function as an anode while reducing the resistance as an interconnect and achieving good ohmic contact with other layers. The overall thickness of the anode 102 is preferably 100 nm to 250 nm.

[0051] In the case of a display device in which light from the light-emitting element is extracted from the anode 102 side, the anode 102 has a transparent electrode with light-transmitting properties. The transparent electrode is made of a light-transmitting material, or if a non-light-transmitting material is used, it is made thin. The light transmittance of the transparent electrode is 40% or more. In other words, 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 shape of the top surface of the anode 102 is not limited, but is shown in FIG. 1 as a rectangle, with the short side of the rectangle aligned along the X direction and the long side of the rectangle aligned along the Y direction.

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

[0054] 3A to 3C are cross-sectional views taken along the dashed line CD of the pixel region 100 shown in Fig. 1. In Figs. 3A to 3C, the end of the anode 102 also has a tapered shape.

[0055] 2A to 3C show the tapered shape of the end of the anode 102 such that the upper side is shorter than the lower side, but it may also have an inverse tapered shape in which the lower side is shorter than the upper side. Of course, the end of the anode 102 may not be tapered, but may have a steep shape in which the upper and lower sides are roughly the same (a shape in which the end is vertical or approximately vertical in cross section).

[0056] The tapered shape includes a region where the anode 102 gradually becomes thinner. The tapered shape can prevent the thin film formed on the anode 102 from being cut or the like.

[0057] The resistance of an anode having the thinned region may gradually increase. That is, the anode 102 includes a region of high resistance corresponding to the tapered shape. The anode having such a high resistance region may be considered to be a region to which a signal supplied from a transistor, specifically a voltage, is difficult to apply.

[0058] <Hole injection layer 104> As shown in FIGS. 1 to 3C, a hole injection layer 104 is formed on an anode 102. Because the hole injection layer 104 is formed on the anode 102, it is less likely to be cut off, which is preferable. Unlike the anode 102, the hole injection layer 104 is not divided into sub-pixels, but is formed over the entire pixel region 100. In other words, the hole injection layer 104 is formed across multiple anodes and can be shared by each sub-pixel. A layer that can be shared by each sub-pixel 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 using the hole injection layer 104 as a common layer, the process of applying a different layer for each sub-pixel is 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, and therefore holes are less likely to be injected from the anode 102 into the hole injection layer 104 at the portion that overlaps with the high resistance region, or holes are not injected at all. By having the hole injection layer 104 have the above-described portion, crosstalk between adjacent light-emitting elements can be suppressed. Crosstalk is the transmission of a signal from a transistor in an adjacent subpixel to a subpixel that is not being driven. Suppressing crosstalk is particularly desirable when adjacent light-emitting elements emit different colors.

[0060] When the hole injection layer 104 is formed on the anode 102 having the inverse tapered shape and the steep-sided shape, the hole injection layer 104 is cut, and therefore the crosstalk is suppressed.

[0061] The effect of providing the hole injection layer 104 and the like along the anode 102 in this manner 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 by a wet method, for example, an inkjet method, a partition into which the solution is dropped is required. The partition can be provided by an insulating material, and such an insulating material may be referred to as a partition wall, a bank, or a partition wall.

[0064] 1 to 3C, partition walls 110 are formed on the hole injection layer 104, and the partition walls 110 are used to define sub-pixels, i.e., light-emitting regions. The partition walls 110 that define the sub-pixels form a lattice pattern when viewed from above the pixel region 100, as shown in FIG. 1. The partition walls 110 have openings 112 that correspond to the sub-pixels, i.e., the light-emitting regions, in cross-sectional views of the pixel region 100, as shown in FIGS. 2A to 3C. When viewed from above, the hole injection layer 104 is exposed through the openings 112, and a solution containing starting materials such as the light-emitting layer 115r can be dropped so as to overlap at least the exposed hole injection layer 104.

[0065] Before dropping the solution containing the starting materials for the light-emitting layer 115r, etc., a solution X containing the starting materials for the hole transport layer may be dropped. After dropping the solution X, the solvent is removed from the solution X through a baking process or the like, and the solution is further hardened to obtain the hole transport layer.

[0066] 2A shows the second region 110y having a corner at its upper end, and FIG. 2B shows the second region 110y having a rounded upper end. FIG. 3A shows the first region 110x having a corner at its upper end, and FIG. 3B shows the first region 110x having a rounded upper end. FIG. 3C shows the first region 110x having a rounded upper end, and the light-emitting layer 115r is also provided on the upper surface of the first region 110x. The light-emitting material contained in the light-emitting layer 115r, i.e., the light-emitting material contained in the starting material, will be described later.

[0067] 2A to 3C, in the cross-sectional views of the pixel region 100, the ends of the partition walls 110 may have a tapered shape. For example, the tapered shape can be achieved by making the lower end of the partition wall 110 longer than the upper end. Furthermore, the partition wall 110 may have an inverse tapered shape in which the lower end is shorter than the upper end. By making the ends of the partition walls 110 tapered, the solution from the inkjet device is dropped into the compartment of the target light-emitting element, making it less likely to be mixed between adjacent light-emitting elements of different colors.

[0068] The tapered shape includes a shape having a region where the partition wall 110 is gradually thinned. The thin film formed on the partition wall 110 having the tapered shape can be prevented from being cut or the like.

[0069] 2A to 3C, the end of the partition 110 may have a tapered shape in which the upper side is shorter than the lower side, or alternatively, the end of the partition 110 may have a reverse tapered shape in which the lower side is shorter than the upper side. Of course, the end of the partition 110 may not have a tapered shape, but may have a steep shape in which the upper side and the lower side are substantially the same (a shape in which the end is vertical or approximately vertical in cross section).

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

[0071] The partition 110 may be formed using an inorganic material containing one or more of aluminum oxide, magnesium oxide, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, and tantalum oxide. Note that materials containing impurity elements such as lanthanum (La), nitrogen, and zirconium (Zr) may also be used. The partition 110 formed from an inorganic material may have corners at the top, as shown in FIGS. 2A and 3A.

[0072] The partition 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. Materials containing impurity elements such as lanthanum (La), nitrogen, or zirconium (Zr) may also be used. The partition 110 formed from an organic material has a rounded upper end, as shown in FIGS. 2B, 3B, and 3C. Having a rounded upper end may be expressed as having a curvature or being rounded.

[0073] It is preferable that the bottom end of the partition wall 110 is also rounded. Although not shown, if a negative photosensitive resin or a positive photosensitive resin is used as the organic material, the top and bottom ends of the partition wall 110 can be rounded.

[0074] <Height of bulkhead 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] 1 to 3C show cases where the second region 110y has a higher uppermost surface position than the first region 110x. In this embodiment, since the positions of the uppermost surfaces of the partition walls 110 are compared, it does not matter whether the film thickness of the first region 110x or the film thickness of the second region 110y is larger. Also, as shown in FIG. 1, the highest point of the uppermost surface of the partition wall 110 is the intersection between the first region 110x and the second region 110y.

[0076] The configuration in which the partition 110 has different heights in the first region 110x and the second region 110y is suitable for an inkjet method using the partition 110 as a formation surface. Fig. 4 shows how the light-emitting layer is applied with different solutions by the inkjet method, and this is preferable because the nozzles 119r, 119g, and 119b of the inkjet device can be moved along the second region 110y, which has a higher uppermost surface.

[0077] 4 shows nozzles 119r, 119g, and 119b, and describes how solutions containing different starting materials for light-emitting layers are dropped from each nozzle, but solutions containing the same starting material for light-emitting layers may 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 suitable for mass production.

[0078] Although FIG. 4 shows partition 110 having a corner at the upper end and a tapered end, corresponding to FIG. 2A, partition 110 may have a rounded upper end and a tapered end as shown in FIG. 2B, or may have other shapes.

[0079] It is preferable to move the inkjet device along the partition wall 110 in the region where the uppermost surface is higher. That is, the uppermost surface of the first region 110x of the partition wall may be 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 regions 110y are arranged between light-emitting elements of different colors. That is, the second regions 110y are arranged between sub-pixels in which light-emitting elements of different colors are formed. The second regions 110y arranged in this manner also have the effect of preventing the solutions ejected from the nozzles from mixing colors between sub-pixels.

[0081] Although it is possible to prevent color mixing without the first region 110x, the solution begins to dry and aggregate the moment it is dropped, and this aggregation is difficult to control. To prevent this aggregation, it is preferable to provide the first region 110x for each subpixel. That is, to prevent color mixing, it is preferable to provide the first region 110x in addition to the second region 110y, so that the solution ejected from the nozzle can remain in the intended 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 be described below. 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, a photosensitive polyimide is used. A polyimide precursor is applied to the entire pixel region 100 and dried. A mask is placed using photoresist or the like so that it overlaps the region to be the second region 110y. Alternatively, a mask is placed so that it overlaps regions other than the second region 110y. When exposure and development are performed using this mask, the polyimide is positioned in accordance with the second region 110y. Then, it is imidized as necessary. In this manner, the second region 110y is 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 through the same steps as those for the second region 110y.

[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, a larger amount of precursor is used when forming the second region 110y than when forming the first region 110x in a strip shape. The second region 110y should have a height 1.5 to 3 times that of the first region 110x. Furthermore, at the intersection, both polyimides are stacked, making the top surface the highest. To control the height of the intersection, the mask position when forming the first region 110x is changed so that the polyimide corresponding to the first region 110x is not formed at the intersection.

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

[0086] <Method 2 for Fabricating the First Region 110x and the Second Region 110y> A method for fabricating the first region 110x and the second region 110y shown in FIG. 1 will be described. Again, the partition 110 can have a laminated structure, such as a lower partition made of an inorganic material and an upper partition made of an organic material. For example, a film of inorganic material that will form the lower partition is first formed over the entire pixel region 100, and then an organic material that will form the upper partition is formed on top of that. This laminated structure is applied to the second region 110y. Then, only the inorganic material or only the organic material is applied to the first region 110x. In this manner, the first region 110x and the second region 110y can also be obtained.

[0087] The upper partition wall can be used as a mask for processing the lower partition wall. Therefore, in a cross-sectional view, the edge of the upper partition wall can be aligned or approximately aligned with the edge of the lower partition wall. Alternatively, the edge of the upper partition wall can be positioned more inward than the edge of the lower partition wall containing an inorganic material.

[0088] In addition, when the upper partition wall is not used as a mask for processing the lower partition wall, the end of the upper partition wall can be positioned outside the end of the lower partition wall made of an inorganic material.

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

[0090] 3C, 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 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] Again, wet methods include spin coating, inkjet printing, casting, printing, dispensing, and spraying. By forming at least the light-emitting layer by a wet method, productivity can be improved. When a display device has flexibility, a configuration in which at least the light-emitting layer is formed by a wet method is highly flexible and suitable.

[0092] Examples of solvents for solutions used in wet methods include chlorine-based solvents such as dichloroethane, trichloroethane, chlorobenzene, and dichlorobenzene; ether-based solvents such as tetrahydrofuran, dioxane, anisole, and methylanisole; aromatic hydrocarbon-based solvents such as toluene, xylene, mesitylene, ethylbenzene, hexylbenzene, and cyclohexylbenzene; aliphatic hydrocarbon-based 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. One or more of these solvents can be used.

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

[0094] <Inkjet devices> 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 referred to as the nozzle diameter) through which the solution is ejected is between several μm and several tens of μm. The part containing the nozzle is sometimes called the head. To dispense the solution, the head is provided with a solution ejection control unit, such as a piezoelectric element. The pressure element can be used to change the volume of the ink tank connected to the nozzle to dispense the solution. The volume of one droplet is often between several pl and several tens of pl, depending on the nozzle diameter. 1 pl of solution can be considered to be the amount that forms a cube with sides of approximately 10 μm.

[0095] The solution may be intermittently dropped from the nozzles 119r, 119g, and 119b. When the solution is dropped intermittently, it may be referred to as droplets. The solution may also be dropped continuously in a line from the nozzles 119r, 119g, and 119b. In both cases of intermittent dropping and continuous dropping, the solution may be applied onto the partition wall 110.

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

[0097] The liquid pools are formed during the drying process, which is carried out in a normal pressure or reduced pressure atmosphere to remove the solvent from the solution discharged by the wet method. In particular, during the drying process in a reduced pressure atmosphere, the surface tension of the solution acts as a driving force, causing the solute to gather outside, resulting in the formation of liquid pools. The liquid pools are areas around the inner periphery of the partition wall 110 (e.g., the area circled with dotted lines in Figures 2A to 3B) where the light-emitting layer is thicker than the center. The liquid pools cause current to concentrate in the center of the light-emitting area, resulting in uneven current density, so the smaller the liquid pools, the better.

[0098] In one embodiment of the present invention, the partition wall 110 is formed on the hole-injection layer 104, so that even if the hole-injection layer 104 is formed by a wet process, no liquid pools are formed in the hole-injection layer 104. That is, in one embodiment of the present invention, minute liquid pools are formed corresponding to the light-emitting layer formed by a wet process. According to such one embodiment of the present invention, a display device having a small liquid pool and a high-resolution pixel region 100 can be provided.

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

[0100] Again, 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, the electron injection layer, and the cathode can be formed over the entire pixel region 100. In other words, the electron transport layer, the electron injection layer, or the cathode that is common to each pixel is a common layer. The electron transport layer, the electron injection layer, and the cathode can be formed by a wet method or a vapor deposition method. When forming a common layer, it is preferable to use a spin coating method as the wet method.

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

[0103] As shown in FIG. 6, the display device includes a pixel region 100 and a driving circuit region. The pixel region 100 in FIG. 6 includes an insulating film 101, an anode 102, a hole injection layer 104, a hole transport layer 105, a partition 110, and a light-emitting layer 115. The partition 110 includes a first region 110x and a second region 110y. The partition 110 is characterized in that the top surface of the second region 110y in the partition 110 is higher than the top 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 may correspond to a light-emitting layer included in a red light-emitting element, the light-emitting layer 115g may correspond to a light-emitting layer included in a green light-emitting element, and the light-emitting layer 115b may correspond to a light-emitting layer included in a blue light-emitting element. The configuration of the pixel region 100 is similar to that of Configuration Example 1, and descriptions of similar portions will be omitted.

[0104] <Insulating film 101> 6, an insulating film 101 is provided on the above-described transistor. The insulating film can have a configuration similar to that of the insulating film 101 in Configuration Example 1, and the configuration and the like are as described in the insulating film 101 in Configuration Example 1. Therefore, a detailed description of the insulating film 101 will be omitted in Configuration Example 2.

[0105] <Anode 102> An anode 102 is provided on the insulating film 101. The anode can have a configuration similar to that of the <anode 102> in Configuration Example 1, and the configuration etc. are as described in the <anode 102> in Configuration Example 1. Therefore, a detailed description of the anode 102 in Configuration Example 2 will be omitted.

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

[0107] 8A to 8C are cross-sectional views taken along the dashed line CD of the pixel region 100 shown in Fig. 6. In Figs. 8A to 8C, the end of the anode 102 also has a tapered shape.

[0108] 7A to 8C show the tapered shape of the end of the anode 102 such that the upper side is shorter than the lower side, but it may also have an inverse tapered shape in which the lower side is shorter than the upper side. Of course, the end of the anode 102 may not be tapered, but may have a steep shape in which the upper and lower sides are roughly the same (a shape in which the end is vertical or approximately vertical in cross section).

[0109] The tapered shape can prevent the thin film formed on the anode 102 from being cut or the like.

[0110] The resistance of an anode having the thinned region may gradually increase. That is, the anode 102 includes a region of high resistance corresponding to the tapered shape. The anode having such a high resistance region may be considered to be a region to which a signal supplied from a transistor, specifically a voltage, is difficult to apply.

[0111] <Hole injection layer 104> 6 to 8C, a hole injection layer 104 is formed on the anode 102. The hole injection layer may have a configuration similar to that of the <Hole injection layer 104> in Configuration Example 1, and the configuration etc. are as described in the <Hole injection layer 104> in Configuration Example 1. Therefore, a detailed description of the hole injection layer 104 in Configuration Example 2 will be omitted.

[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 not divided into sections for each pixel like the anode 102, but is formed over the entire pixel region 100. In other words, the hole transport layer 105 is formed across multiple anodes and can be shared by each pixel. Again, a layer that can be shared by each subpixel will be 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 using the hole transport layer 105 as a common layer, a process of applying different layers for each subpixel is 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, and therefore the hole transport layer 105 has difficulty transporting holes or is unable to transport holes in the portion that overlaps with the high resistance region. The hole transport layer 105 has the above region, making it possible to suppress crosstalk between adjacent light-emitting elements of different colors.

[0114] As described in Configuration Example 1, in the portion of the hole injection layer 104 that overlaps with the high resistance region, holes are less likely to be injected into the hole injection layer 104 from the anode 102, or holes are not 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 the hole transport layer 105 is formed on the anode 102 having the inverse tapered shape and the steep-sided shape, the hole transport layer 105 is cut, thereby suppressing the crosstalk.

[0116] The effect of providing the hole transport layer 105 and the like along the anode 102 in this manner is the suppression of crosstalk.

[0117] <Bulkhead 110> In this embodiment, since the light-emitting layer is applied by a wet method, for example, an inkjet method, a partition into which the solution is dropped is required. The partition can be provided by an insulating material, and such an insulating material may be referred to as a partition wall, a bank, or a partition wall.

[0118] 6 to 8C, a partition 110 is formed on the hole transport layer 105, and the partition 110 is used to partition sub-pixels, i.e., light-emitting regions. The partition 110 may have a structure similar to that of the <partition 110> in Configuration Example 1, and the structure and the like are the same as those described in the <partition 110> in Configuration Example 1. Therefore, a detailed description of the partition 110 in Configuration Example 2 will be omitted.

[0119] <Height of bulkhead 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] 6 to 8C show cases where the second region 110y has a higher uppermost surface than the first region 110x. In this embodiment, the positions of the uppermost surfaces of the partition walls 110 are compared, so it does not matter whether the film thickness of the first region 110x or the film thickness of the second region 110y is larger. Also, as shown in FIG. 6, the highest point of the uppermost surface of the partition wall 110 is the intersection between the first region 110x and the second region 110y.

[0121] The configuration in which the partition 110 has different heights in the first region 110x and the second region 110y is suitable for an inkjet method using the partition 110 as a formation surface. Fig. 9 shows how the light-emitting layer is applied with different solutions by the inkjet method, and this is preferable because the nozzles 119r, 119g, and 119b of the inkjet device can be moved along the second region 110y, which has a higher uppermost surface.

[0122] 9 shows nozzles 119r, 119g, and 119b, and describes how solutions containing starting materials for different light-emitting layers are dropped from each nozzle, but solutions containing starting materials for the same light-emitting layer may 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 suitable for mass production.

[0123] Although FIG. 9 shows partition 110 having a corner at the upper end and a tapered end, corresponding to FIG. 7A, partition 110 may have a rounded upper end and a tapered end as shown in FIG. 7B, or may have other shapes. In FIG. 9, the inkjet device can be moved along the partition wall 110 in the region where the uppermost surface is located at a high position.

[0124] It is preferable to move the inkjet device along the partition wall 110 in the region where the uppermost surface is higher. That is, the uppermost surface of the first region 110x of the partition wall may be 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 regions 110y are arranged between light-emitting elements of different colors. That is, the second regions 110y are arranged between sub-pixels corresponding to light-emitting elements of different colors. The second regions 110y arranged in this manner also have the effect of preventing the solution ejected from the nozzles from mixing colors between sub-pixels.

[0126] Although it is possible to prevent color mixing without the first region 110x, the solution begins to dry and aggregate the moment it is dropped, and this aggregation is difficult to control. To prevent this aggregation, it is preferable to provide the first region 110x for each subpixel. That is, to prevent color mixing, it is preferable to provide the first region 110x in addition to the second region 110y, so that the solution ejected from the nozzle can remain in the intended light-emitting region.

[0127] <Method 3 for Fabricating the First Region 110x and the Second Region 110y> The manufacturing methods of the first region 110x and the second region 110y shown in FIG. 6 can be similar to the <Manufacturing method 1 of the first region 110x and the second region 110y> and <Manufacturing method 2 of the first region 110x and the second region 110y> in Configuration Example 1, and detailed descriptions of these methods will be omitted.

[0128] <Light-emitting layers 115r, 115g, 115b> After forming the partition wall 110, the light-emitting layers 115r, 115g, and 115b are formed on the hole transport layer 105 by coating, as shown in Figures 6 to 9. This coated structure corresponds to a light-emitting element with an SBS structure. The light-emitting colors of the light-emitting layers 115r, 115g, and 115b correspond to red, green, and blue, which are typical colors of a full-color display.

[0129] The light-emitting layers 115r, 115g, and 115b are formed by a wet process. The wet process or the like can be the same as the specific method and materials described in the <Light-emitting layers 115r, 115g, and 115b> of Configuration Example 1, and the method or the structure or the like is the same as described in the <Light-emitting layers 115r, 115g, and 115b> of Configuration Example 1. Therefore, detailed description thereof will be omitted in Configuration Example 2.

[0130] 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 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] <Inkjet devices> 9, the inkjet device has nozzles 119r, 119g, and 119b. The inkjet device and the like can be configured in the same manner as described in <Regarding the Inkjet Device> of Configuration Example 1, and are as described in <Regarding the Inkjet Device> of Configuration Example 1. Therefore, in Configuration Example 2, detailed description of <Regarding the Inkjet Device> will be omitted.

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

[0133] The liquid pools are formed during the drying process, which is carried out in a normal or reduced pressure atmosphere to remove the solvent from the solution discharged by the wet method. In particular, during the drying process in a reduced pressure atmosphere, the surface tension of the solution acts as a driving force, causing the solute to gather outside, resulting in the formation of liquid pools. The liquid pools are the areas around the inner periphery of the partition wall 110 (e.g., the areas circled with dotted lines in Figures 7A to 8B) where the light-emitting layer is thicker than the center. The liquid pools cause current to concentrate in the center of the light-emitting area, resulting in uneven current density, so the smaller the liquid pools, the better.

[0134] In one embodiment of the present invention, the partition wall 110 is formed on the hole-transport layer 105, so that even if the hole-transport layer 105 is formed by a wet process, no liquid pools are formed in the hole-transport layer. That is, in one embodiment of the present invention, minute liquid pools are formed corresponding to the light-emitting layer formed by a wet process. According to such one embodiment of the present invention, a display device having a small liquid pool and a high-resolution pixel region 100 can be provided.

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

[0136] 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, the electron injection layer, and the cathode can be formed over the entire pixel region 100. That is, the electron transport layer, the electron injection layer, and the cathode are common layers for each pixel. The electron transport layer, the electron injection layer, and the cathode can be formed by a wet method or a vapor deposition method. When forming them as common layers, it is preferable to use a spin coating method as the wet method.

[0137] The contents described in this embodiment mode can be used in combination with other embodiment modes.

[0138] (Embodiment 2) In this embodiment, a light-emitting element that can be used for a display device that is one embodiment of the present invention will be described.

[0139] <Configuration example of light-emitting element> 11A, the light-emitting element 20 has a light-emitting unit 686 between a pair of electrodes (a lower electrode 672 and an upper electrode 688). The light-emitting unit 686 has a plurality of functional layers, such as a layer 4430, a light-emitting layer 4421, and a layer 4420, in this order from the lower electrode 672. In one embodiment of the present invention, a partition 110 is provided for the functional layers formed by a wet method. For example, when the light-emitting layer 4421 is formed by a wet method, the partition 110 is provided over the layer 4430 to partition the light-emitting layer 4421. Although not shown, the partition 110 has a first region and a second region with 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] The layer 4420 and the layer 4430 will be described. For example, when the lower electrode 672 is an anode and the upper electrode 688 is a cathode as in the above embodiment, the layer 4430 located over the lower electrode 672 may have a structure in which a hole-injection layer, a hole-transport layer, and the like are stacked in this order from the lower electrode. Note that the layer 4430 may be either a hole-injection layer or a hole-transport layer. The layer 4420 may have a structure in which an electron-injection layer, an electron-transport layer, and the like are stacked in this order from the upper electrode. The layer 4420 may be either an electron-injection layer or an electron-transport layer.

[0142] Although different from the above embodiment, the lower electrode 672 may be a cathode and the upper electrode 688 may be an anode. In this case, the layer 4430 located over the lower electrode 672 may have a structure in which an electron injection layer, an electron transport layer, and the like are stacked in this order from the lower electrode. The layer 4430 may be either an electron injection layer or an electron transport layer. The layer 4420 may have a structure in which a hole injection layer, a hole transport layer, and the like are stacked in this order from the upper electrode. The layer 4430 may be either a hole injection layer or a hole transport layer.

[0143] The bottom electrode 672 can be formed by evaporation, CVD, or sputtering. The top electrode 688 can be formed by evaporation, CVD, or sputtering. The layer 4430 can be formed by a wet method or evaporation. The layer 4420 can be formed by a wet method or evaporation.

[0144] 11A, the partition 110 is formed on the layer 4430, and the light-emitting layer 4421 is formed on the layer 4430 exposed from the partition 110 in a top view by a wet method such as an inkjet method. The layer 4420 and the upper electrode 688 can be a common layer, and as shown in FIG. 11A, the layer 4420 and the upper electrode 688 are preferably formed to extend beyond the partition 110. It is preferable to thicken the common layer so that it can extend beyond the partition 110. If there are restrictions on thickening the common layer, the light-emitting layer 4421 may also be thickened. In this case, for example, the amount of solution dropped from the inkjet device is preferably adjusted so that the film thickness of the light-emitting layer is 2 / 3 or more and less than 1 times the height of the partition 110.

[0145] Next, a more specific configuration than that shown in FIG. 11A is shown in FIG. 11B. The light-emitting element 20 shown in FIG. 11B includes a layer 4430-1 on the lower electrode 672, a layer 4430-2 on the layer 4430-1, a light-emitting layer 4421 on the layer 4430-2, a layer 4420-1 on the light-emitting layer 4421, a layer 4420-2 on the layer 4420-1, and an upper electrode 688 on the layer 4420-2. A partition wall 110 is positioned relative to the layers formed by a wet process. For example, when the light-emitting layer 4421 is formed by a wet process, the partition wall 110 is provided on the layer 4430-2 to separate the light-emitting layer 4421. Although not shown, the partition wall 110 has a first region and a second region having different heights, as described in the above embodiment.

[0146] For example, if the lower electrode 672 is an anode and the upper electrode 688 is a cathode as in the above embodiment, 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] Also, although different from the above embodiment, the lower electrode 672 can be a cathode and the upper electrode 688 can be an anode. In this case, the layer 4430-1 functions as an electron injection layer, the layer 4430-2 functions as an electron transport layer, the layer 4420-1 functions as a hole transport layer, and the layer 4420-2 functions as a hole injection layer.

[0148] Such a layer structure makes it possible to efficiently inject carriers (holes and electrons) into the light-emitting layer 4421 and increase the efficiency of carrier recombination in the light-emitting layer 4421. Note that the layers included between the light-emitting layer 4421 and the lower electrode 672 and the layer included between the light-emitting layer 4421 and the upper electrode 688 are not limited to these, and may include a carrier block layer, an exciton block layer, or the like as appropriate. Furthermore, a layer having both a carrier transport function and a carrier injection function may be used.

[0149] The bottom electrode 672 can be formed by evaporation, CVD, or sputtering. The top electrode 688 can be formed by evaporation, CVD, or sputtering. The layer 4430-1 can be formed by a wet method or evaporation. The layer 4430-2 can be formed by a wet method or evaporation. The layer 4420-1 can be formed by a wet method or evaporation. The layer 4420-2 can be formed by a wet method or evaporation.

[0150] 11B, the partition 110 is formed on the layer 4430-2, and the light-emitting layer 4421 is formed by a wet method such as an inkjet method on the layer 4430-2 exposed from the partition 110 in a top view. The layer 4420-1, the layer 4420-2, and the upper electrode 688 can be a common layer, and as shown in FIG. 11B, the layer 4420-1, the layer 4420-2, and the upper electrode 688 are preferably formed to extend beyond the partition 110. It is preferable to thicken the common layer so that it can extend beyond the partition 110. If there are restrictions on thickening the common layer, the light-emitting layer 4421 may also be thickened. In this case, for example, the amount of solution dispensed from the inkjet device may be adjusted so that the film thickness of the light-emitting layer is at least 2 / 3 and less than 1 times the height of the partition 110.

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

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

[0153] The light-emitting materials contained in the multiple light-emitting layers in Figures 11C1 and 11C2 can be selected from light-emitting materials of the same color or light-emitting materials of different colors. Selecting light-emitting materials of the same color increases the driving voltage, but allows for a reduction in driving current, which is advantageous in terms of increasing brightness and extending life. In Figures 11C1 and 11C2, full-color display is possible by painting each light-emitting element with a light-emitting material of the same color, blue (B), green (G), and red (R).

[0154] When light-emitting materials of different colors are selected, a light-emitting element that emits white light can be obtained by selecting light-emitting materials that have complementary colors. For example, in FIG. 11C1, the light-emitting color of the first light-emitting layer 4411 and the light-emitting color of the third light-emitting layer 4413 are made the same, and light-emitting materials are used so that the light-emitting color and the light-emitting color of the second light-emitting layer 4412 are complementary colors, thereby enabling white light emission from the light-emitting element 20. Furthermore, in FIG. 11C2, the light-emitting element 20 can emit white light by using light-emitting materials so that the light-emitting color of the first light-emitting layer 4411 and the light-emitting color of the second light-emitting layer 4412 are complementary colors. When white light is emitted and a full-color display is desired, a method of obtaining desired colors such as blue (B), green (G), and red (R) using a color filter or a color conversion layer can be used.

[0155] Although the configurations shown in FIGS. 11C1 and 11C2 have three and two stacked light-emitting layers, four or more layers may also be used.

[0156] 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 an inkjet method. The lower electrode 672 and the upper electrode 688 can be formed by evaporation, CVD, or sputtering. The layer 4430 and the layer 4420 can be formed by a wet method or evaporation. Among them, the layer 4420 and the upper electrode 688 can be shared among multiple light-emitting elements and are referred to as a common layer. The common layer is formed over the entire pixel region. The common layer is formed over the partition wall 110. However, if the common layer is not cut by the partition wall 110, it is preferable to thicken the common layer. If there is a limit to the thickness, it is preferable to adjust the amount of solution dropped from the inkjet device 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 2 / 3 or more and less than 1 times the height of the partition wall 110.

[0157] Note that the layers 4420 and 4430 in FIGS. 11C1 and 11C2 may have a laminated structure consisting of two or more layers as shown in FIG. 11B.

[0158] Next, modifications of FIG. 11C2 are shown in FIGS. 11D1 and 11D2. Both FIGS. 11D1 and 11D2 show examples of structures in which light-emitting units are stacked. Both FIGS. 11D1 and 11D2 share a common structure in which a first light-emitting unit 686a and a second light-emitting unit 686b are provided with an intermediate layer 690 therebetween. In FIG. 11D2, the intermediate layer has a stacked structure of intermediate layers 690a and 690b. The first light-emitting unit 686a includes a layer 4430-1, a first light-emitting layer 4411, and a layer 4420-1. The second light-emitting unit 686b includes a layer 4430-2, a second light-emitting layer 4412, and a layer 4420-2. A partition wall 110 is positioned relative to the layers formed by a wet process. For example, when the first light-emitting layer 4411 and the second light-emitting layer 4412 are formed by a wet process, a partition 110 is provided to separate the first light-emitting layer 4411 and the second light-emitting layer 4412. Although not shown, the partition 110 has a first region and a second region with different heights as described in the above embodiment modes.

[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] Intermediate layer 690 shown in FIG. 11D1 has a dopant material in a similar material to layer 4420-1 and an acceptor material in a similar material to layer 4430-2.

[0161] Intermediate layer 690a shown in FIG. 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] 11D1 and 11D2, as in FIG. 11C2, the light-emitting materials contained in the plurality of light-emitting layers can be selected to be light-emitting substances of the same color or light-emitting substances of different colors. When light-emitting substances 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 life. When light-emitting substances of different colors are selected, selecting light-emitting substances that are complementary colors can provide a light-emitting element that emits white light.

[0163] In Figures 11D1 and 11D2, as in Figure 11C2, when white light is emitted and a full-color display is desired, one method is to use a color filter or color conversion layer to obtain the desired colors, such as blue (B), green (G), and red (R).

[0164] In FIGS. 11D1 and 11D2, similarly to FIG. 11C2, full-color display is possible by painting each light-emitting element with a different luminescent color (for example, blue (B), green (G), and red (R)).

[0165] The color purity can be further improved by adding a microcavity structure to the light-emitting device 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, specifically the distance, differs for each emitted color.

[0166] To vary the optical distance between the upper electrode 688 and the lower electrode 672, it is preferable to vary the thickness of the lower electrode 672. When the thickness of the lower electrode 672 is varied and the lower electrode 672 has a laminated structure of a first conductive film and a second conductive film on the first conductive film, varying the film thickness of the second conductive film makes it easier to impart a microcavity structure.

[0167] Here, examples of materials for each functional layer of the light emitting element will be described.

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

[0169] The hole injection layer may be formed from a substance having acceptor properties. Examples of such acceptor substances include organic compounds having electron-withdrawing groups (e.g., halogen groups, cyano groups, etc.). Compounds in which an electron-withdrawing group is bonded to a fused aromatic ring containing multiple heteroatoms, such as 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), are particularly preferred because of their thermal stability. Radialene derivatives having electron-withdrawing groups (e.g., halogen groups such as fluoro groups, cyano groups, etc.) are also preferred because of their extremely high electron-accepting properties.

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

[0171] The hole injection layer may be formed of a composite material containing the above-mentioned material having acceptor properties and a material having hole transport properties. As the material having hole transport properties used in the composite material, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, or polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. The material having hole transport properties used in the composite material is preferably a 1×10 -6 cm 2 A material having a hole mobility of 1 / Vs or more is preferred. The material having hole transport properties used in the composite material is preferably a compound having a fused aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the fused aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferred. Furthermore, as the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferred, specifically a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to one of these is preferred. Furthermore, other aromatic amine compounds can be used as the material having hole transport properties.

[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 that contains a hole transport material. The hole transport material is a material having a concentration of 1×10 -6 cm 2A substance having a hole mobility of 1 / Vs or more is preferred. Note that any substance that has a higher hole transporting property than electron transporting property can be used as the hole transporting material. Specifically, a material having a high hole transporting property, such as a π-electron-rich heteroaromatic compound or an aromatic amine, is preferred as the hole transporting material.

[0173] The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton in the ring, and specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to one of these rings is preferred.

[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 that contains an electron transporting material. The electron transporting material is a material having a molecular weight of 1×10 -6 cm 2 Substances having an electron mobility of 1 / Vs or higher are preferred. Note that other materials that transport electrons more efficiently than holes can also be used as electron-transporting materials. Examples of such electron-transporting materials include metal complexes and organic compounds having a π-electron-deficient heteroaromatic ring skeleton. Specifically, materials with high electron transporting properties, such as metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well 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, and other π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds, can be used. In particular, heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, and heterocyclic compounds having a pyridine skeleton are preferred due to their high reliability. Among these, heterocyclic compounds having a diazine (such as pyrimidine or pyrazine) or triazine skeleton have 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 contains a material with high electron injection properties. Examples of the material with high electron injection properties include alkali metals, alkaline earth metals, and compounds or complexes thereof. Materials for the electron injection layer include an electride or a layer made of a substance with electron transport properties containing an alkali metal, alkaline earth metal, or a compound thereof.

[0176] The electron injection layer may be formed using a material having electron transport properties. For example, a compound having an electron-deficient heteroaromatic ring with an uncommon electron pair can be used as the material having electron transport properties. 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(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), can be used.

[0177] The light-emitting layer is a layer containing a light-emitting material (also referred to as a light-emitting substance). The light-emitting layer can contain one or more light-emitting substances. As the light-emitting substance, a substance that emits light of blue, purple, blue-purple, green, yellow-green, yellow, orange, or red is appropriately used. Furthermore, a substance that emits near-infrared light can also be used as the light-emitting substance.

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

[0179] Although known materials can be used as the fluorescent material, 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, and naphthalene derivatives. In particular, condensed aromatic diamine compounds, such as pyrene diamine compounds, are preferred because of their high hole-trapping properties, excellent luminous efficiency, and reliability.

[0180] Examples of phosphorescent materials include organometallic complexes (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a carbene skeleton, a pyrimidine skeleton, a pyrazine skeleton, a pyridine skeleton, or a quinoline skeleton; organometallic complexes (particularly iridium complexes) having a phenylpyridine derivative having an electron-withdrawing group as a ligand; platinum complexes; and rare earth metal complexes.

[0181] Examples of TADF materials that can be used include fullerene and its derivatives, acridine and its derivatives, eosin derivatives, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), and heterocyclic compounds having either 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, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, or pyridazine skeleton), and triazine skeleton are all preferred as TADF materials due to their stability and high reliability. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are all preferred as TADF materials due to their high acceptor properties and high reliability. Furthermore, among skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are all preferred as TADF materials due to their stability and high reliability. It is preferable that a TADF material have at least one of these skeletons. The dibenzofuran skeleton is preferred as a furan skeleton, and the dibenzothiophene skeleton is preferred as a thiophene skeleton. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton is particularly preferred.

[0183] In addition, when both a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring are present, a π-electron-deficient skeleton or a π-electron-rich skeleton can be used in place of at least one of them. Examples of the π-electron-rich skeleton include an aromatic amine skeleton, a phenazine skeleton, and the like. Examples of the π-electron-deficient skeleton include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, or a sulfone skeleton.

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

[0185] The light-emitting layer preferably contains, for example, a phosphorescent material, a hole-transporting material, and an electron-transporting material. The hole-transporting material and the electron-transporting material are a combination that easily form an exciplex. With this configuration, light emission can be efficiently obtained using Exciplex-Triplet Energy Transfer (ExTET), which is energy transfer from the exciplex to the light-emitting material (phosphorescent material). By selecting a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, energy transfer becomes smooth and light emission can be efficiently obtained. With this configuration, high efficiency, low-voltage operation, and long life of the light-emitting element can be simultaneously achieved.

[0186] In one embodiment of the present invention, the light-emitting layer is formed by a wet method such as an ink-jet method. A solution in which the above-described various materials are dissolved or dispersed in a solvent can be used. In this case, various organic solvents can be used as the solvent. Furthermore, a material such as a polymer material, a low-molecular-weight material, or a dendrimer having a desired function can be mixed and used as is or dispersed or dissolved in a solvent to form a solution.

[0187] In addition, when it is desired to form the light-emitting layer using a polymer, a solution containing one or more mixed monomers of the polymer material to be formed into a film may be discharged onto the film-forming surface, and the desired film may be formed by forming bonds such as crosslinking, condensation, polymerization, coordination, or salt by heating or irradiating with energy light.

[0188] The solution may contain organic compounds having other functions, such as surfactants or viscosity adjusting substances.

[0189] Examples of polymer materials that can be used include conjugated polymers, non-conjugated polymers, pendant-type polymers, and dye-blend-type polymers. Examples of conjugated polymers include poly(p-phenylenevinylene; PPV), polyalkylthiophene derivatives (poly(3-alkylthiophene; PAT), polyparaphenylene derivatives (poly(1,4-phenylene; PPP), polyfluorene derivatives (poly(9,9-dialkylfluorene; PDAF), and copolymers thereof. Examples of pendant-type polymers include vinyl polymers, such as polyvinylcarbazole derivatives (PVK).

[0190] In addition, various organic solvents 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, and cyclohexane can be used as the solvent. In particular, the use of low-polarity benzene derivatives such as benzene, toluene, xylene, and mesitylene is preferred because it allows the preparation of a solution with a suitable concentration and prevents the materials contained in the solution from deteriorating due to oxidation or other reasons. Furthermore, in consideration of the uniformity of the film or the uniformity of the film thickness after production, solvents with a boiling point of 100°C or higher are preferred, and toluene, xylene, and mesitylene are even more preferred.

[0191] <Layer 4430 Materials> Note that in one embodiment of the present invention, in addition to the light-emitting layer, the layer 4430 may be formed by a wet method. Since the layer 4430 can be a common layer, a spin coating method is preferably used as the wet method. Specifically, after the bottom electrode 672 is formed, the layer 4430 can be formed by a spin coating method or the like without patterning.

[0192] When the lower electrode 672 is an anode, it is preferable that the above-described skeleton having high hole transport properties and a material exhibiting acceptor properties are simultaneously contained in the layer 4430. When the layer 4430 is formed by a wet method, examples of the material exhibiting acceptor properties include a sulfonic acid compound, a fluorine compound, a trifluoroacetic acid compound, a propionic acid compound, and a metal oxide.

[0193] When layer 4430 is formed by a wet method and a solution containing mixed monomers is applied, it is preferable to use a secondary amine and an arylsulfonic acid as the monomers.

[0194] The secondary amine can be a substituted or unsubstituted aryl group having 6 to 14 carbon atoms or a substituted or unsubstituted π-electron-rich heteroaryl group having 6 to 12 carbon atoms. Examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, and an anthryl group. A phenyl group is preferred because of its excellent solubility and low cost. Examples of the heteroaryl group include a carbazole skeleton, a pyrrole skeleton, a thiophene skeleton, a furan skeleton, and an imidazole skeleton. Multiple bonds via arylamines or heteroarylamines are preferred to improve film quality, and the compound may be an oligomer or polymer. When multiple amines are present, 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 preferably 1,000 or less, more preferably 10 or less, and the molecular weight is preferably 100,000 or less. Fluorine substitution is also preferred because it improves compatibility with fluorine-substituted compounds.

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

[0196] [ka]

[0197] However, in the above general formula (G1), Ar 11 ~Ar 13 One or more of these represent hydrogen, and Ar 14 ~Ar 17 represents a substituted or unsubstituted aromatic ring having 6 to 14 carbon atoms, and Ar 14 ~Ar 17 represents 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, an anthracene ring, or the like can be used. 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. Furthermore, p represents an integer of 0 or more and 1,000 or less, and preferably 0 or more and 3 or less. The molecular weight of the organic compound represented by the 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 preferred.

[0199] [ka]

[0200] However, in the above general formula (G2), Ar 21 ~Ar 23 represents a substituted or unsubstituted aryl group having 6 to 14 carbon atoms, which may be bonded to each other to form a ring. 21 ~Ar 23When the alkyl group has a substituent, the substituent may be a group in which multiple diarylamino groups or carbazolyl groups are linked together. The substituent may also have a bond via an ether bond, a sulfide bond, or an amine. When multiple aryl groups are included, these bonds are preferred because they improve the solubility in organic solvents. When the alkyl group has a substituent, the bond may also be via an ether bond, a sulfide bond, or an amine.

[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 a solution. 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 preferred because it can form bonds with the mixed sulfonic acid compound through a dehydration reaction or the like. When the compound to be mixed with the amine compound is a fluoride, using a fluoride as the amine compound, such as those represented by the above structural formulas (Am2-1), (Am2-22) to (Am2-28), or (Am2-31), improves compatibility and is therefore preferred.

[0208] A thiophene derivative may be used instead of the secondary amine. Specific examples of the thiophene derivative include organic compounds represented by the following structural formulas (T-1) to (T-4), polythiophene, and poly(3,4-ethylenedioxythiophene) (PEDOT). When a thiophene derivative is mixed with a sulfonic acid compound, carriers are easily generated, improving conductivity. Mixing with a sulfonic acid compound is sometimes referred to as p-doping.

[0209] [ka]

[0210] Sulfonic acid compounds are materials that exhibit acceptor properties. Examples of sulfonic acid compounds include arylsulfonic acids. Arylsulfonic acids may contain a sulfo group, and sulfonic acid, sulfonate salts, alkoxysulfonic acids, halogenated sulfonic acids, or sulfonate anions may be used. These sulfo groups may be present in multiple forms. The aryl group contained in the arylsulfonic acid may be a substituted or unsubstituted aryl group having 6 to 16 carbon atoms. Examples of aryl groups include phenyl, biphenyl, naphthyl, fluorenyl, phenanthrenyl, anthryl, and pyrenyl groups. Naphthyl groups are particularly preferred due to their excellent solubility and transportability in organic solvents. Arylsulfonic acids may contain multiple aryl groups. Furthermore, fluorine-substituted aryl groups are preferred because the LUMO level can be adjusted to a deep (largely negative) position. The arylsulfonic acid may have an ether bond, a sulfide bond, or a bond via an amine. When the arylsulfonic acid has multiple aryl groups, these bonds are preferred because they improve solubility in organic solvents. Even when the arylsulfonic acid has an alkyl group as a substituent, the bonds may be via an ether bond, a sulfide bond, or an amine. The arylsulfonic acid may be substituted with a polymer. Examples of polymers that can be used include polyethylene, nylon, polystyrene, and polyfluorenylene, but polystyrene and polyfluorenylene are preferred because of their good conductivity.

[0211] Specific examples of compounds containing arylsulfonic acid (arylsulfonic acid compounds) include organic compounds represented by the following structural formulas (S-1) to (S-15). Polymers containing sulfo groups, such as poly(4-styrenesulfonic acid) (PSS), can also be used. The use of arylsulfonic acid compounds allows them to accept electrons from electron donors with shallow HOMOs (such as amine compounds, carbazole compounds, or thiophene compounds). Mixing with an electron donor can provide hole injection or hole transport properties from an electrode. The use of fluorine compounds as arylsulfonic acid compounds allows for adjustment of the LUMO level to a deeper level (more negative energy level).

[0212] [ka]

[0213] [ka]

[0214] [ka]

[0215] [ka]

[0216] A tertiary amine may be further mixed into the solution obtained by mixing the secondary amine and the sulfonic acid compound. Tertiary amines are electrochemically and optically more stable than secondary amines, and mixing improves hole transport properties. As the tertiary amine, for example, organic compounds represented by the following structural formulas (Am3-1) to (Am3-7) are preferable. In addition to the tertiary amine, a material having hole transport properties may be appropriately mixed into the solution.

[0217] [ka]

[0218] [ka]

[0219] In addition to arylsulfonic acid compounds, cyano compounds such as tetracyanoquinodimethane compounds can also be used as electron acceptors, such as 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) or dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN6).

[0220] It is preferable that the solution containing the above-mentioned monomers contains either or both of a 3,3,3-trifluoropropyltrimethoxysilane compound and a phenyltrimethoxysilane compound, since this improves wettability when the film is formed by a wet method.

[0221] When a layer formed by a wet process using a solution containing at least two monomers, an electron donor such as a secondary amine or thiophene and an arylsulfonic acid, is measured by ToF-SIMS in negative mode, a signal is observed near m / z=80. The m / z=80 signal is derived from the SO3 anion in the arylsulfonic acid. On the other hand, signals derived from the amine monomer are hardly observed in the layer. If a light-emitting device having the layer exhibits sufficient light emission, this is evidence that the layer has sufficient hole transport capability. When the above signal or other analytical results are obtained in a light-emitting device capable of emitting light, the layer is found to have sufficient hole transport capability. The absence of an amine or other skeleton responsible for hole transport capability suggests that the monomers are bonded together to form a polymeric compound film. These analytical results indicate that the layer was formed by a wet process.

[0222] Sulfonic acid compounds represented by the structural formula (S-1) or (S-2) above are preferred because they contain many sulfo groups, can form three-dimensional bonds with amine compounds, and tend to stabilize the film quality. In layers prepared using these aryl sulfonic acid compounds, in addition to the signal at m / z=80, a signal at m / z=901 is observed in negative mode. A signal at m / z=328 is also observed as a product ion.

[0223] <Light-emitting materials> In the light-emitting element of one embodiment of the present invention, an iridium complex represented by the following structural formula is preferably used as a light-emitting material: The following iridium complex is preferably soluble in an organic solvent and can be easily prepared as a solution because it has an alkyl group.

[0224] [ka]

[0225] When an emitting layer containing the iridium complex represented by the above structural formula is measured by ToF-SIMS in positive mode, a signal appears at m / z=1676 or the product ions m / z=1181 and m / z=685.

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

[0227] When the intermediate layer has two layers as shown in FIG. 11D2, the intermediate layer may have an organic compound layer containing an acceptor material and an organic compound layer containing a donor material.

[0228] The organic compound layer containing an acceptor material is preferably formed using the composite material exemplified above as a material capable of forming the hole injection layer or the hole transport layer.

[0229] An acceptor material is a material that can generate holes in an organic compound by causing charge separation between the acceptor material and another organic compound whose LUMO level and HOMO level are close to each other. For example, compounds having an electron-withdrawing group (halogen group or cyano group), such as quinodimethane derivatives, chloranil derivatives, or hexaazatriphenylene derivatives, can be used as organic acceptor materials. For example, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: 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-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile, and the like can be used. Among organic acceptor materials, compounds such as HAT-CN, in which an electron-withdrawing group is bonded to a fused aromatic ring containing multiple heteroatoms, are particularly suitable because of their high acceptability and thermal stability. Radialene derivatives containing electron-withdrawing groups (especially halogen groups such as fluoro groups or cyano groups) are also preferred because of their extremely high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0230] The donor material may be a substance with high electron injection properties, such as an alkali metal, an alkaline earth metal, a rare earth metal, or a compound thereof. Examples of the alkali metal compounds include oxides such as lithium oxide or halides, and further examples of the alkali metal compounds include carbonates such as lithium carbonate or cesium carbonate. Examples of the alkaline earth metal compounds include oxides, halides, or carbonates, and further examples of the rare earth metal compounds include oxides, halides, or carbonates.

[0231] The organic compound layer containing a donor material can be formed using the same materials as those constituting the electron transport layer or electron injection layer described above.

[0232] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification and the like.

[0233] (Embodiment 3) In this embodiment, a structural example of a pixel circuit and an example of a driving method thereof which can be applied to a display device of one embodiment of the present invention will be described.

[0234] [Pixel circuit configuration example] 12A includes a transistor M1, a transistor M2, a capacitor C1, and a light-emitting element EL. The pixel circuit PIX1 is electrically connected to a wiring SL, a wiring GL, a wiring AL, and a wiring CL.

[0235] The transistor M1 has a gate electrically connected to a wiring GL, one of its source and drain electrically connected to a wiring SL, and the other electrically connected to the gate of the transistor M2 and one electrode of the capacitor C1. The transistor M2 has one of its source and drain electrically connected to a wiring AL, and the other electrically connected to the anode of the light-emitting element EL. The capacitor C1 has the other electrode electrically connected to the anode of the light-emitting element EL. The light-emitting element EL has a cathode electrically connected to a wiring CL.

[0236] The transistor M1 can also be called a selection transistor and functions as a switch for controlling the selection and non-selection of a pixel. The transistor M2 can also be called a drive transistor and has the function of controlling the current flowing through the light-emitting element EL. The capacitor C1 functions as a storage capacitor and has the function of holding the gate potential of the transistor M2. The capacitor C1 may be a capacitive element such as an MIM capacitor, or the capacitance between wirings or the gate capacitance of a transistor may be used as the capacitor C1.

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

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

[0239] 12B is configured by adding a transistor M3 to the pixel circuit PIX1, and is electrically connected to a line V0.

[0240] The transistor M3 has a gate electrically connected to the wiring GL, one of a source and a drain electrically connected to the anode of the light-emitting element EL, and the other electrically connected to the wiring V0.

[0241] A constant potential is applied to the wiring V0 when data is written to the pixel circuit PIX2, which makes it possible to suppress variations in the gate-source voltage of the transistor M3.

[0242] The pixel circuit PIX3 shown in FIG. 12C is an example in which transistors having a pair of gates electrically connected are used as the transistors M1 and M2 of the pixel circuit PIX1. The pixel circuit PIX4 shown in FIG. 12D is an example in which transistors having a pair of gates electrically connected are used as the pixel circuit PIX2. This increases the current that can be passed through the transistors. Note that, although transistors having a pair of gates electrically connected are used for all the transistors here, this is not a limitation. Alternatively, transistors having a pair of gates electrically connected to different wirings may be used. For example, reliability can be improved by using a transistor in which one of the gates is electrically connected to a source.

[0243] 13A has a configuration in which a transistor M4 is added to the above-mentioned PIX2. Furthermore, the pixel circuit PIX5 is electrically connected to wirings (wirings GL1, GL2, and GL3) that function as three gate lines.

[0244] The gate of the transistor M4 is electrically connected to a wiring GL3, one of the source and drain of the transistor M4 is electrically connected to the gate of the transistor M2, and the other is electrically connected to a wiring V0. The gate of the transistor M1 is electrically connected to a wiring GL1, and the gate of the transistor M3 is electrically connected to a wiring GL2. The wiring V0 may be arranged to intersect with the wiring AL.

[0245] By simultaneously turning on transistors M3 and M4, the source and gate of transistor M2 have the same potential, turning off transistor M2. This forcibly cuts off the current flowing through the light-emitting element EL. This pixel circuit is suitable for use in a display method that alternates between display periods and off periods.

[0246] 13B is an example in which a capacitor C2 is added to the pixel circuit PIX5 described above. The capacitor C2 functions as a storage capacitor.

[0247] 13C and 13D are examples in which transistors each having a pair of gates are applied to the pixel circuit PIX5 or PIX6, respectively. Transistors M1, M3, and M4 are transistors in which a pair of gates are electrically connected, and transistor M2 is a transistor in which one gate is electrically connected to its source.

[0248] [Driving method example] An example of a method for driving a display device to which pixel circuit PIX5 is applied will be described below. Note that the same driving method can also be applied to pixel circuits PIX6, PIX7, and PIX8.

[0249] 14 shows a timing chart relating to a method for driving a display device using the pixel circuit PIX5. The chart shows the transitions in potential of the wirings GL1[k], GL2[k], and GL3[k], which are gate lines in the kth row, and the wirings GL1[k+1], GL2[k+1], and GL3[k+1], which are gate lines in the k+1th row. The chart also shows the timing of signals applied to the wirings SL, which function as source lines.

[0250] Here, an example of a driving method is shown in which one horizontal period is divided into a light-on period and a light-off period. The horizontal period for the kth row and the horizontal period for the k+1th row are shifted by the selection period of the gate line.

[0251] During the lighting period of the kth row, a high-level potential is first applied to the wiring GL1[k] and the wiring GL2[k], and a source signal is applied to the wiring SL. This brings the transistors M1 and M3 into conduction, and a potential corresponding to the source signal is written from the wiring SL to the gate of the transistor M2. After that, a low-level potential is applied to the wiring GL1[k] and the wiring GL2[k], bringing the transistors M1 and M3 into non-conduction, and the gate potential of the transistor M2 is maintained.

[0252] Next, the lighting period of the k+1th row begins, and data is written by the same operation as above.

[0253] Next, the off period will be described. During the off period of the kth row, a high-level potential is applied to the wiring GL2[k] and the wiring GL3[k]. As a result, the transistors M3 and M4 are turned on, and the same potential is applied to the source and gate of the transistor M2, so that almost no current flows through the transistor M2. This turns off the light-emitting element EL. All pixels located on the kth row are turned off. The pixels on the kth row remain off until the next lighting period.

[0254] Next, the process transitions to the off period of the k+1th row, and all the pixels of the k+1th row are in the off state in the same manner as above.

[0255] This driving method, in which the display is not always on throughout one horizontal period but has an off period during one horizontal period, can also be called duty driving. By using duty driving, the afterimage phenomenon can be reduced when displaying moving images, making it possible to realize a display device with high video display performance. In particular, in VR devices, reducing afterimages can help alleviate so-called VR sickness.

[0256] In duty drive, the ratio of the on period to one horizontal period can be called the duty ratio. For example, a duty ratio of 50% means that the on period and the off period are the same length. The duty ratio can be freely set and can be adjusted as needed within a range of, for example, more than 0% and less than 100%.

[0257] The above is a description of an example of a driving method.

[0258] The contents described in this embodiment mode can be used in combination with other embodiment modes.

[0259] (Fourth embodiment) In this embodiment, a structural example of a display device according to one embodiment of the present invention will be described.

[0260] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, smartphones, wristwatch-type terminals, tablet terminals, personal digital assistants, and sound reproducing devices.

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

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

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

[0264] The circuit 464 can be, for example, a scanning line driver circuit.

[0265] The wiring 465 has a function of supplying signals and power to the display portion 462 and the circuit 464. The signals and power are input to the wiring 465 from the outside via the FPC 472 or input to the wiring 465 from the IC 473.

[0266] 15 shows an example in which an IC 473 is provided on a substrate 451 by a COG (Chip On Glass) method or a COF (Chip on Film) method. The IC 473 may be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. The display device 400A and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by a COF method or the like.

[0267] FIG. 16A shows an example of a cross section of display device 400A, in which a part of the region including FPC 472, a part of circuit 464, a part of display unit 462, and a part of the region including the end portion are cut away.

[0268] The display device 400A shown in Figure 16A has, between a substrate 451 and a substrate 452, 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.

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

[0270] Here, when a pixel of a display device has three types of sub-pixels having light-emitting elements that emit different colors, examples of the three sub-pixels include a combination of R, G, and B, or a combination of yellow (Y), cyan (C), and magenta (M). When a pixel of a display device has four sub-pixels, examples of the four sub-pixels include a combination of R, G, B, and white (W), or a combination of R, G, B, and Y. A pixel can have three or more sub-pixels as the smallest unit capable of displaying full color.

[0271] The protective layer 416 and the substrate 452 are bonded via an adhesive layer 442. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting element. In FIG. 16A, a 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), and a hollow sealing structure is applied. The adhesive layer 442 may be provided so as to overlap the light-emitting element. Furthermore, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from the adhesive layer 442.

[0272] Light-emitting elements 430a, 430b, and 430c have an optical adjustment layer between a pixel electrode and a 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. For details of the light-emitting elements, refer to Embodiments 1 to 3.

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

[0274] The pixel electrodes and the edges of the optical adjustment layer are covered with 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 section 462, or may be separated into sub-pixel regions. A layer 435 having an electron transport layer and an electron injection layer is provided on the light-emitting layer provided in the opening of the insulating layer 421 and 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] Light emitted from the light-emitting element is emitted toward the substrate 452. The substrate 452 is preferably made of a material that is highly transparent to visible light.

[0276] Note that the insulating layer 421 may have a stacked structure of an inorganic insulating film and an organic insulating film. When the insulating layer 421 has a stacked structure of an inorganic insulating film and an organic insulating film, the inorganic insulating film is preferably used as a lower layer. In the display device of one embodiment of the present invention, the insulating layer 421 is provided over the hole-injection layer 431. Therefore, 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, which may be caused when an organic solvent is used to form the organic insulating film.

[0277] The transistor 201 and the transistor 205 are both formed over a substrate 451. These transistors can be manufactured using the same material and through the same process.

[0278] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 451 in this order. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0279] At least one insulating layer covering the transistor is preferably made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. With this structure, it is possible to effectively prevent impurities from diffusing into the transistor from the outside, thereby improving the reliability of the display device.

[0280] It is preferable to use an inorganic insulating film for each of the insulating layers 211, 213, and 215. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film may also be used. Two or more of the above insulating films may be stacked.

[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 can prevent impurities from entering from the edge of the display device 400A through the organic insulating film. Alternatively, the organic insulating film may be formed so that the edge of the organic insulating film is located inside 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 suitable for the insulating layer 214, which functions as a planarizing layer. Materials that can be used for the organic insulating film include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins.

[0283] 16A, an opening is formed in insulating layer 214. This makes it possible to prevent impurities from entering display unit 462 from the outside through insulating layer 214, even when an organic insulating film is used for insulating layer 214. This makes it possible to improve the reliability of display device 400A.

[0284] The transistor 201 and the transistor 205 each include 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 a source and a 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 structure of the transistor included in the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0286] The transistor 201 and the transistor 205 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0287] The crystallinity of the semiconductor material used for the transistor is not particularly limited, and any of an amorphous semiconductor, a single-crystal semiconductor, and a semiconductor having crystallinity other than single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a single-crystal semiconductor or a crystalline semiconductor is preferable because it can suppress deterioration of the transistor characteristics.

[0288] The semiconductor layer of the transistor preferably contains metal oxide (also referred to as an oxide semiconductor). That is, the display device of this embodiment preferably uses a transistor using metal oxide in a channel formation region (hereinafter referred to as an OS transistor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon and single-crystal silicon).

[0289] The semiconductor layer preferably contains, for example, indium, M (wherein M is one or more elements 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 elements selected from aluminum, gallium, yttrium, and tin.

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

[0291] When the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include compositions in which In:M:Zn=1:1:1 or thereabouts, In:M:Zn=1:1:1.2 or thereabouts, In:M:Zn=2:1:3 or thereabouts, In:M:Zn=3:1:2 or thereabouts, In:M:Zn=4:2:3 or thereabouts, In:M:Zn=4:2:4.1 or thereabouts, In:M:Zn=5:1:3 or thereabouts, In:M:Zn=5:1:6 or thereabouts, In:M:Zn=5:1:7 or thereabouts, In:M:Zn=5:1:8 or thereabouts, In:M:Zn=6:1:6 or thereabouts, and In:M:Zn=5:2:5 or thereabouts, etc. Note that "nearby compositions" includes 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 thereabout, this includes a case where, when the atomic ratio of In is 4, the atomic ratio of Ga is 1 to 3 and the atomic ratio of Zn is 2 to 4. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=5:1:6 or thereabout, this includes a case where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 5 and less than 7. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=1:1:1 or thereabout, this includes a case where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 0.1 and less than 2.

[0293] The transistors included in the circuit 464 may have the same structure as or different from the transistors included in the display portion 462. The transistors included in the circuit 464 may all have the same structure or may have two or more types of structures. Similarly, the transistors included in the display portion 462 may all have the same structure or may have two or more types of structures.

[0294] A connection portion 204 is provided in an area of ​​the substrate 451 where the substrate 452 does not overlap. In the connection portion 204, a wiring 465 is electrically connected to the FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 has an example of a laminated structure 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 the 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 substrate 452 facing substrate 451. In addition, various optical members can be arranged on the outside of substrate 452. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light-collecting film. In addition, an antistatic film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses the occurrence of scratches during use, an impact absorbing layer, etc. may be arranged on the outside of substrate 452.

[0296] By providing the protective layer 416 that covers the light-emitting element, impurities such as water can be prevented from entering the light-emitting element, and the reliability of the light-emitting element can be improved.

[0297] In region 228 near the edge of display device 400A, insulating layer 215 and protective layer 416 preferably contact each other through the opening in insulating layer 214. In particular, it is preferable that the inorganic insulating film of insulating layer 215 and the inorganic insulating film of protective layer 416 contact each other. This makes it possible to prevent impurities from entering display unit 462 from the outside via the organic insulating film. This can therefore improve the reliability of display device 400A.

[0298] 16B shows an example in which the protective layer 416 has a three-layer structure. In FIG. 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 ends of inorganic insulating layer 416a and inorganic insulating layer 416c extend outward beyond the ends of organic insulating layer 416b and are in contact with each other. Inorganic insulating layer 416a is in contact with insulating layer 215 (inorganic insulating layer) through an opening in insulating layer 214 (organic insulating layer). This allows the insulating layer 215 and protective layer 416 to surround the light-emitting element, thereby improving the reliability of the light-emitting element.

[0300] In this way, 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 end of the inorganic insulating film extends further outward than the end of the organic insulating film.

[0301] The substrate 451 and the substrate 452 can each be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A material that transmits light is used for the substrate on the side from which light from the light-emitting element is extracted. Using a flexible material for the substrate 451 and the substrate 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used for the substrate 451 or the substrate 452.

[0302] Substrate 451 and substrate 452 can be made of polyester resin such as polyethylene terephthalate (PET) or 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, polyamideimide 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 having a thickness sufficient to provide flexibility.

[0303] When a circularly polarizing plate is superimposed on a display device, it is preferable that the display device has a substrate with high optical isotropy. A substrate with high optical isotropy has small birefringence (or a small amount of birefringence).

[0304] The absolute value of the retardation (phase difference) of a substrate having high optical isotropy 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 triacetyl cellulose (TAC, also known as cellulose triacetate) films, cycloolefin polymer (COP) films, cycloolefin copolymer (COC) films, and acrylic films.

[0306] Furthermore, when a film is used as a substrate, the film may absorb water, causing deformation such as wrinkles 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 preferably 0.1% or less, and even more preferably 0.01% or less.

[0307] The adhesive layer can be made of various curable adhesives, such as photo-curable adhesives (e.g., ultraviolet curable), reactive curable adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. Materials with low moisture permeability, such as epoxy resin, are particularly preferred. Two-component resins may also be used. Adhesive sheets, etc., may also be used.

[0308] The connection layer 242 may be made of an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0309] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0310] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, can be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) can be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them sufficiently to ensure light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These can also be used for conductive layers such as various wirings and electrodes constituting a display device, and for conductive layers (conductive layers functioning as pixel electrodes or common electrodes) of light-emitting elements.

[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 oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0312] [Display device 400B] Fig. 17 shows a cross-sectional view of the display device 400B. The perspective view of the display device 400B is similar to that of the display device 400A (Fig. 15). Fig. 17 shows an example of a cross-section of the display device 400B, when a portion of an area including the FPC 472, a portion of the circuit 464, and a portion of the display unit 462 are cut away. Note that descriptions of portions similar to those of the display device 400A may be omitted.

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

[0314] The display device 400B includes a display portion 462, a circuit 464, wiring 465, and the like. Therefore, the display device 400B shown in Fig. 17 can also be considered a display module including the display device 400B, an IC (integrated circuit), and an FPC.

[0315] The circuit 464 can be, for example, a scanning line driver circuit.

[0316] The wiring 465 has a function of supplying signals and power to the display portion 462 and the circuit 464. The signals and power are input to the wiring 465 from the outside via the FPC 472 or input to the wiring 465 from the IC 473.

[0317] The display module shows an example in which an IC 473 is provided on a substrate 451 by a COG (Chip On Glass) method or a COF (Chip on Film) method. The IC 473 can be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. Note that the display device 400B and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by a COF method or the like.

[0318] FIG. 17 shows an example of a cross section of the display device 400B, where a part of the region including the FPC 472, a part of the circuit 464, a part of the display unit 462, and a part of the region including the end portion are cut away.

[0319] The display device 400B shown in Figure 17 has, between a substrate 451 and a substrate 452, 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.

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

[0321] Here, when a pixel of a display device has three types of subpixels having light-emitting elements that emit different colors, the three subpixels include subpixels of three colors R, G, and B, or subpixels of three colors yellow (Y), cyan (C), and magenta (M), etc. When a pixel of a display device has four subpixels, the four subpixels include subpixels of four colors R, G, B, and white (W), or subpixels of four colors R, G, B, and Y, etc.

[0322] The protective layer 416 and the substrate 452 are bonded via an adhesive layer 442. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting element. In FIG. 17, a 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), and a hollow sealing structure is applied. The adhesive layer 442 may be provided so as to overlap the light-emitting element. Furthermore, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from the adhesive layer 442.

[0323] Light-emitting elements 430a, 430b, and 430c have an optical adjustment layer between a pixel electrode and a 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. For details of the light-emitting elements, refer to Embodiments 1 to 3.

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

[0325] The pixel electrodes and the edges of the optical adjustment layer are covered with 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 section 462, or may be separated into sub-pixel regions. A layer 435 having an electron transport layer and an electron injection layer is provided on the light-emitting layer provided in the opening of the insulating layer 421 and 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] Light emitted from the light-emitting element is emitted toward the substrate 454. The substrate 454 is preferably made of a material that is highly transparent to visible light.

[0327] Note that the insulating layer 421 may have a stacked structure of an inorganic insulating film and an organic insulating film. When the insulating layer 421 has a stacked structure of an inorganic insulating film and an organic insulating film, the inorganic insulating film is preferably used as a lower layer. In the display device of one embodiment of the present invention, the insulating layer 421 is provided over the hole-injection layer 431. Therefore, 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, which may be caused when an organic solvent is used to form the organic insulating film.

[0328] The transistor 201 and the transistor 205 are both formed over a substrate 451. These transistors can be manufactured using the same material and through the same process.

[0329] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 451 in this order. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0330] At least one insulating layer covering the transistor is preferably made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. With this structure, it is possible to effectively prevent impurities from diffusing into the transistor from the outside, thereby improving the reliability of the display device.

[0331] It is preferable to use an inorganic insulating film for each of the insulating layers 211, 213, and 215. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film may also be used. Two or more of the above insulating films may be stacked.

[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 can prevent impurities from entering from the edge of the display device 400B through the organic insulating film. Alternatively, the organic insulating film may be formed so that the edge of the organic insulating film is located inside 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 suitable for the insulating layer 214, which functions as a planarizing layer. Materials that can be used for the organic insulating film include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins.

[0334] 17, an opening is formed in insulating layer 214. This makes it possible to prevent impurities from entering display section 462 from the outside through insulating layer 214, even when an organic insulating film is used for insulating layer 214. This makes it possible to improve the reliability of display device 400B.

[0335] The transistor 201 and the transistor 205 each include 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 a source and a 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 structure of the transistor included in the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0337] The transistor 201 and the transistor 205 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0338] The crystallinity of the semiconductor material used for the transistor is not particularly limited, and any of an amorphous semiconductor, a single-crystal semiconductor, and a semiconductor having crystallinity other than single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a single-crystal semiconductor or a crystalline semiconductor is preferable because it can suppress deterioration of the transistor characteristics.

[0339] The semiconductor layer of the transistor preferably contains metal oxide (also referred to as an oxide semiconductor). That is, the display device of this embodiment preferably uses a transistor using metal oxide in a channel formation region (hereinafter referred to as an OS transistor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon and single-crystal silicon).

[0340] The semiconductor layer preferably contains, for example, indium, M (wherein M is one or more elements 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 elements selected from aluminum, gallium, yttrium, and tin.

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

[0342] When the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include compositions in which In:M:Zn=1:1:1 or thereabouts, In:M:Zn=1:1:1.2 or thereabouts, In:M:Zn=2:1:3 or thereabouts, In:M:Zn=3:1:2 or thereabouts, In:M:Zn=4:2:3 or thereabouts, In:M:Zn=4:2:4.1 or thereabouts, In:M:Zn=5:1:3 or thereabouts, In:M:Zn=5:1:6 or thereabouts, In:M:Zn=5:1:7 or thereabouts, In:M:Zn=5:1:8 or thereabouts, In:M:Zn=6:1:6 or thereabouts, and In:M:Zn=5:2:5 or thereabouts, etc. Note that "nearby compositions" includes 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 thereabout, this includes a case where, when the atomic ratio of In is 4, the atomic ratio of Ga is 1 to 3 and the atomic ratio of Zn is 2 to 4. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=5:1:6 or thereabout, this includes a case where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 5 and less than 7. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=1:1:1 or thereabout, this includes a case where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 0.1 and less than 2.

[0344] The transistors included in the circuit 464 may have the same structure as or different from the transistors included in the display portion 462. The transistors included in the circuit 464 may all have the same structure or may have two or more types of structures. Similarly, the transistors included in the display portion 462 may all have the same structure or may have two or more types of structures.

[0345] A connection portion 204 is provided in an area of ​​the substrate 451 where the substrate 452 does not overlap. In the connection portion 204, a wiring 465 is electrically connected to the FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 has an example of a laminated structure 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 the 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 substrate 452 facing substrate 451. In addition, various optical members can be arranged on the outside of substrate 452. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light-collecting film. In addition, an antistatic film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses the occurrence of scratches during use, an impact absorbing layer, etc. may be arranged on the outside of substrate 452.

[0347] By providing the protective layer 416 that covers the light-emitting element, impurities such as water can be prevented from entering the light-emitting element, and the reliability of the light-emitting element can be improved.

[0348] In region 228 near the edge of display device 400B, insulating layer 215 and protective layer 416 preferably contact each other through the opening in insulating layer 214. In particular, it is preferable that the inorganic insulating film of insulating layer 215 and the inorganic insulating film of protective layer 416 contact each other. This makes it possible to prevent impurities from entering display unit 462 from the outside via the organic insulating film. This can therefore improve the reliability of display device 400B.

[0349] 16B, protective layer 416 of display device 400B may have a laminated structure of an organic insulating film and an inorganic insulating film. In this case, it is preferable that the end of the inorganic insulating film extends further outward than the end of the organic insulating film.

[0350] The substrate 451 and the substrate 452 can each be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A material that transmits light is used for the substrate on the side from which light from the light-emitting element is extracted. Using a flexible material for the substrate 451 and the substrate 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used for the substrate 451 or the substrate 452.

[0351] Substrate 451 and substrate 452 can be made of polyester resin such as polyethylene terephthalate (PET) or 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, polyamideimide 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 having a thickness sufficient to provide flexibility.

[0352] When a circularly polarizing plate is superimposed on a display device, it is preferable that the display device has a substrate with high optical isotropy. A substrate with high optical isotropy has small birefringence (or a small amount of birefringence).

[0353] The absolute value of the retardation (phase difference) of a substrate having high optical isotropy 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 triacetyl cellulose (TAC, also known as cellulose triacetate) films, cycloolefin polymer (COP) films, cycloolefin copolymer (COC) films, and acrylic films.

[0355] Furthermore, when a film is used as a substrate, the film may absorb water, causing deformation such as wrinkles 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 preferably 0.1% or less, and even more preferably 0.01% or less.

[0356] The adhesive layer can be made of various curable adhesives, such as photo-curable adhesives (e.g., ultraviolet curable), reactive curable adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. Materials with low moisture permeability, such as epoxy resin, are particularly preferred. Two-component resins may also be used. Adhesive sheets, etc., may also be used.

[0357] The connection layer 242 may be made of an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0358] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0359] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, can be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) can be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them sufficiently to ensure light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These can also be used for conductive layers such as various wirings and electrodes constituting a display device, and for conductive layers (conductive layers functioning as pixel electrodes or common electrodes) of light-emitting elements.

[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 oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0361] [Display device 400C] FIG. 18A shows a cross-sectional view of display device 400C. The perspective view of display device 400C is similar to that of display device 400A (FIG. 15). FIG. 18A shows an example of a cross-section of display device 400C, where a portion of a region including FPC 472, a portion of circuit 464, and a portion of display unit 462 are cut away. FIG. 18A shows an example of a cross-section of display unit 462, where a region including light-emitting element 430b that emits green light and light-emitting element 430c that emits blue light is cut away. Note that descriptions of parts similar to those of display device 400A may be omitted.

[0362] A display device 400C shown in FIG. 18A includes a transistor 202, a transistor 210, a light-emitting element 430b, a light-emitting element 430c, and the like between a substrate 453 and a substrate 454.

[0363] The substrate 454 and the protective layer 416 are bonded together via an adhesive layer 442. The adhesive layer 442 is provided to overlap the light emitting element 430b and the light emitting element 430c, respectively, and a solid sealing 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 display device 400C is manufactured by first bonding a fabrication substrate provided with the insulating layer 212, the transistors, the light-emitting elements, and the like to a substrate 454 provided with a light-shielding layer 417 with an adhesive layer 442. Then, the fabrication substrate is peeled off and a substrate 453 is attached to the exposed surface, thereby transferring each component formed on the fabrication substrate to the substrate 453. The substrate 453 and the substrate 454 are preferably flexible. This can increase the flexibility of the display device 400C.

[0366] The insulating layer 212 can be formed using the inorganic insulating film that can be used for the insulating layer 211, the insulating layer 213, and the insulating layer 215, respectively.

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

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

[0369] An edge of the pixel electrode 411 is covered with 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 portion 462, or may be separated for each sub-pixel region. A layer 435 having an electron transport layer and an electron injection layer is provided on the light-emitting layer provided in the opening of the insulating layer 421 and on the insulating layer 421, and a counter electrode 418 is provided on the layer 435. The pixel electrode 411 contains a material that reflects visible light, and the counter electrode 418 contains a material that transmits visible light.

[0370] Light emitted from the light emitting elements 430b and 430c is emitted toward the substrate 454. The substrate 454 is preferably made of a material that is highly transparent to visible light.

[0371] A connection portion 204 is provided in a region of the substrate 453 where the substrate 454 does not overlap. In the connection portion 204, a wiring 465 is electrically connected to the FPC 472 via a conductive layer 466 and a 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 the FPC 472 to be electrically connected via the connection layer 242.

[0372] The transistor 202 and the transistor 210 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a semiconductor layer including a channel formation 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 functioning as a gate insulating layer, a conductive layer 223 functioning 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 formation region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel formation region 231i.

[0373] The conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through an opening provided in the insulating layer 215. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

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

[0375] On the other hand, in the transistor 209 shown in FIG. 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 FIG. 18B can be manufactured by processing the insulating layer 225 using the conductive layer 223 as a mask. In FIG. 18B, the insulating layer 215 is provided to cover the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through openings in the insulating layer 215. Furthermore, an insulating layer 218 may be provided to cover the transistor.

[0376] [Display device 400D] 19A shows a cross-sectional view of display device 400D. The perspective view of display device 400D is similar to that of display device 400A (FIG. 15), and therefore, a description of the same parts as those of display device 400A will be omitted. Specifically, display device 400D differs from display device 400A in that it has a hole transport layer 432 on a hole injection layer 431, but the other parts are similar to those of display device 400A, and therefore a description of the same parts will be omitted.

[0377] Since the display device 400D has the hole transport layer 432 on the hole injection layer 431, the edges of the pixel electrodes and the 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 may be separated into sub-pixel regions.

[0378] Note that the insulating layer 421 may have a stacked structure of an inorganic insulating film and an organic insulating film. When the insulating layer 421 has a stacked structure of an inorganic insulating film and an organic insulating film, the inorganic insulating film is preferably used as a lower layer. In the display device of one embodiment of the present invention, the insulating layer 421 is provided over the hole-transport layer 432. Therefore, by providing the inorganic insulating film on the hole-transport layer 432 side, it is possible to suppress adverse effects on the hole-transport layer 432, which may be caused when an organic solvent is used to form the organic insulating film.

[0379] 19B shows an example in which protective layer 416 has a three-layer structure. Again, display device 400D differs from display device 400A in that it has a hole transport layer 432 on hole injection layer 431, but the other configurations are the same as those of display device 400A, and therefore a description of the similar parts will be omitted.

[0380] [Display device 400E] 20 shows a cross-sectional view of display device 400E. The perspective view of display device 400E is similar to that of display device 400A (FIG. 15), and therefore a description of the same parts as those of display device 400A will be omitted. Specifically, display device 400D differs from display device 400A in that it has a hole transport layer 432 on a hole injection layer 431, but the other parts are similar to those of display device 400A, and therefore a description of the same parts will be omitted.

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

[0382] Since the display device 400E has the hole transport layer 432 on the hole injection layer 431, the end of the pixel electrode is covered with 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 may be separated into sub-pixel regions.

[0383] Note that the insulating layer 421 may have a stacked structure of an inorganic insulating film and an organic insulating film. When the insulating layer 421 has a stacked structure of an inorganic insulating film and an organic insulating film, the inorganic insulating film is preferably used as a lower layer. In the display device of one embodiment of the present invention, the insulating layer 421 is provided over the hole-transport layer 432. Therefore, by providing the inorganic insulating film on the hole-transport layer 432 side, it is possible to suppress adverse effects on the hole-transport layer 432, which may be caused when an organic solvent is used to form the organic insulating film.

[0384] [Display device 400F] 21A shows a cross-sectional view of display device 400F. The perspective view of display device 400F is similar to that of display device 400A (FIG. 15), and therefore a description of the same parts as those of display device 400A will be omitted. Specifically, display device 400D differs from display device 400A in that it has a hole transport layer 432 on a hole injection layer 431, but the other parts are similar to those of display device 400A, and therefore a description of the same parts will be omitted.

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

[0386] Since the display device 400F has the hole transport layer 432 on the hole injection layer 431, the end of the pixel electrode 411 is covered with 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 may be separated into sub-pixel regions.

[0387] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification and the like.

[0388] (Embodiment 5) In this embodiment, a metal oxide (also referred to as an oxide semiconductor) that can be used for the OS transistor described in the above embodiment will be described.

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

[0390] Furthermore, the metal oxide can be formed by a sputtering method, a chemical vapor deposition (CVD) method such as a metal organic chemical vapor deposition (MOCVD) method, or an atomic layer deposition (ALD) method.

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

[0392] The crystalline structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectra. For example, it can be evaluated using XRD spectra obtained by GIXD (Grazing-Incidence XRD) measurements. The GIXD method is also called the thin film method or the Seemann-Bohlin method.

[0393] For example, for a quartz glass substrate, the peak shape of the XRD spectrum is nearly symmetrical. On the other hand, for an IGZO film with a crystalline structure, the peak shape of the XRD spectrum is asymmetrical. The asymmetrical peak shape of the XRD spectrum 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] The crystalline structure of a film or substrate can also be evaluated by the diffraction pattern (also called the nanobeam electron diffraction pattern) observed using nanobeam 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. Furthermore, a spot-like pattern is observed in the diffraction pattern of an IGZO film deposited at room temperature, rather than a halo. For this reason, it is estimated that an IGZO film deposited at room temperature is neither crystalline nor amorphous, but is in an intermediate state, and it cannot be concluded that it is in an amorphous state.

[0395] <<Oxide semiconductor structure>> Note that oxide semiconductors may be classified differently from the above when focusing on their structures. For example, oxide semiconductors are divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the above-mentioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0396] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0397] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction can be 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 the atomic arrangement is considered as a lattice arrangement, a crystalline region can also be a region with a uniform lattice arrangement. Furthermore, CAAC-OS has a region where multiple crystalline regions are connected in the ab-plane direction, and the region may have distortion. Note that distortion refers to a location where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with a different uniform lattice arrangement in the region where multiple crystalline regions are connected. In other words, CAAC-OS is an oxide semiconductor with a c-axis aligned but no clear orientation in the ab-plane direction.

[0398] Each of the multiple crystalline regions 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 one minute crystal, the maximum diameter of the crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of the crystalline region may be several tens of nm.

[0399] In an In-M-Zn oxide (wherein M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), the CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium (In) and oxygen (hereinafter referred to as an In layer) and a layer containing M, zinc (Zn), and oxygen (hereinafter referred to as an (M, Zn) layer) are stacked. Note that indium and the element M are mutually substituted. Therefore, the (M, Zn) layer may contain indium. The In layer may contain M. The In layer may contain Zn. The layered structure is observed as a lattice image in a high-resolution transmission electron microscope (TEM) image, for example.

[0400] When the CAAC-OS film is subjected to structural analysis using, for example, an XRD apparatus, a peak indicating c-axis orientation is detected at or near 2θ=31° in out-of-plane XRD measurement using θ / 2θ scan. Note that the position of the peak indicating c-axis orientation (2θ value) may vary depending on the type and composition of the metallic elements constituting the CAAC-OS.

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

[0402] When the crystalline region is observed from the specific direction, the lattice arrangement within the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. The distortion may also have a pentagonal, heptagonal, or other lattice arrangement. In the CAAC-OS, no clear grain boundaries are observed even near the distortion. This indicates that the formation of grain boundaries is suppressed by the distortion of the lattice arrangement. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of close-packed oxygen atom arrangement in the ab-plane direction and the change in interatomic bond distance caused by metal atom substitution.

[0403] A crystal structure with clear grain boundaries is called polycrystalline. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in the on-state current and field-effect mobility of a transistor. Therefore, CAAC-OS, which lacks clear grain boundaries, is one of the crystalline oxides with a crystal structure suitable for use in the semiconductor layer of a transistor. Zn is preferred for use in CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are suitable because they can suppress the generation of grain boundaries more effectively than In oxide.

[0404] CAAC-OS is an oxide semiconductor with high crystallinity and no clear crystal grain boundaries. Therefore, it can be said that the CAAC-OS is less susceptible to a decrease in electron mobility due to crystal grain boundaries. Furthermore, since the crystallinity of an oxide semiconductor can be reduced by impurities or defects, the CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, oxide semiconductors with CAAC-OS have stable physical properties. Therefore, oxide semiconductors with CAAC-OS are heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even under high temperatures (so-called thermal budgets) during the manufacturing process. Therefore, using a CAAC-OS for an OS transistor can increase the flexibility of the manufacturing process.

[0405] [nc-OS] The nc-OS has periodic atomic arrangement in a microscopic region (e.g., a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In other words, the nc-OS has microcrystalline structures. The size of the microcrystalline structures is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore these microcrystalline structures are also called nanocrystalline structures. Furthermore, the nc-OS exhibits no regularity in the crystal orientation between different nanocrystalline structures. Therefore, the entire film lacks orientation. Therefore, depending on the analytical method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor. For example, when a structural analysis of an nc-OS film is performed using an XRD system, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Furthermore, when an nc-OS film is subjected to electron diffraction (also known as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of nanocrystalline structures (e.g., 50 nm or larger), a halo-like diffraction 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 nanocrystals (for example, 1 nm to 30 nm), an electron diffraction pattern can be obtained in which multiple spots are observed within a ring-shaped region centered on the direct spot.

[0406] [a-like OS] The a-like OS is an oxide semiconductor having a structure between the nc-OS and the amorphous oxide semiconductor. The a-like OS has a pore or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and CAAC-OS.

[0407] <<Oxide semiconductor structure>> Next, the above-mentioned CAC-OS will be described in detail, which relates to the material composition.

[0408] [CAC-OS] CAC-OS is a material structure in which elements constituting a metal oxide are unevenly distributed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range. Hereinafter, a metal oxide in which one or more metal elements are unevenly distributed and the regions containing the metal elements are mixed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range, is also referred to as a mosaic or patch state.

[0409] Furthermore, CAC-OS has a mosaic structure in which the material is separated into first and second regions, and the first regions are distributed throughout the film (hereinafter also referred to as a cloud structure). That is, CAC-OS is a composite metal oxide having a structure in which the first and second regions are mixed.

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

[0411] Specifically, the first region is a region whose main component is indium oxide, indium zinc oxide, or the like. The second region is a region whose main component is gallium oxide, gallium zinc oxide, or the like. In other words, the first region can be rephrased as a region whose main component is In. The second region can be rephrased as a region whose main component is Ga.

[0412] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0413] In addition, CAC-OS in In-Ga-Zn oxide refers to a material structure containing In, Ga, Zn, and O, in which some regions primarily composed of Ga and other regions primarily composed of In are randomly arranged in a mosaic pattern. Therefore, it is presumed that CAC-OS has a structure in which metal elements are distributed nonuniformly.

[0414] The CAC-OS can be formed, for example, by a sputtering method without heating the substrate. When the CAC-OS is formed by a sputtering method, one or more of an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. The lower the flow rate ratio of oxygen gas to the total flow rate of deposition gas during deposition, the better. For example, the flow rate ratio of oxygen gas to the total flow rate of deposition gas during deposition is preferably 0% or more and less than 30%, and more preferably 0% or more and 10% or less.

[0415] Furthermore, for example, in the case of CAC-OS in an In-Ga-Zn oxide, EDX mapping obtained using EDX (Energy Dispersive X-ray spectroscopy) confirms that the CAC-OS has a structure in which a region containing In as a main component (first region) and a region containing Ga as a main component (second region) are unevenly distributed and mixed.

[0416] Here, the first region has higher conductivity than the second region. That is, the flow of carriers through the first region causes the metal oxide to exhibit conductivity. Therefore, the first region is distributed in a cloud-like manner in the metal oxide, thereby achieving a high field-effect mobility (μ).

[0417] On the other hand, the second region has higher insulating properties than the first region. That is, the second region is distributed in the metal oxide, thereby suppressing leakage current.

[0418] Therefore, when CAC-OS is used in a transistor, the conductivity due to the first region and the insulating property due to the second region act complementarily, thereby providing the CAC-OS with a switching function (the ability to turn on / off). In other words, CAC-OS has a conductive function in part of the material and an insulating function in part of the material, and the material as a whole functions as a semiconductor. By separating the conductive function from 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 behavior can be achieved.

[0419] Furthermore, a transistor using CAC-OS has high reliability, making it ideal for various semiconductor devices such as display devices.

[0420] Oxide semiconductors have a variety of structures, each with different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

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

[0422] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0423] For the transistor, an oxide semiconductor having a low carrier concentration is preferably used. For example, the carrier concentration of the oxide semiconductor is 1×10 17 cm -3 Less than 1 × 10 15 cm -3 or less, more preferably 1 × 10 13 cm -3Less than 1×10, more preferably 11 cm -3 or less, more preferably 1 × 10 10 cm -3 Less than 1 x 10 -9 cm -3 That is all. Note that in order to reduce the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor. Note that an oxide semiconductor having a low carrier concentration may also be referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.

[0424] Furthermore, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states, and therefore the density of trap states may also be low.

[0425] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to disappear and may behave like fixed charges. Therefore, a transistor in which a channel formation region is formed in an oxide semiconductor with a high density of trap states may have unstable electrical characteristics.

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

[0427] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0428] When an oxide semiconductor contains silicon or carbon, which is one of the Group 14 elements, defect levels are formed 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 calculated to be 2×10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0429] Furthermore, when an oxide semiconductor contains an alkali metal or alkaline earth metal, defect levels may be formed and carriers may be generated. Therefore, a transistor using an oxide semiconductor containing an alkali metal or alkaline earth metal is likely to have normally-on characteristics. Therefore, when the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 Do the following:

[0430] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Alternatively, when nitrogen is contained in an oxide semiconductor, trap states may be formed. As a result, the electrical characteristics of the transistor may become unstable. For this reason, the nitrogen concentration in the oxide semiconductor obtained by SIMS is set to 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than 1×10, more preferably 18 atoms / cm 3 Less than 5 × 10, more preferably 17 atoms / cm 3 Do the following:

[0431] Furthermore, hydrogen contained in an oxide semiconductor may react with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. When hydrogen enters the oxygen vacancy, electrons serving as carriers may be generated. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons serving as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. For this reason, it is preferable to reduce the amount of hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in an oxide semiconductor measured by SIMS is 1×10 20 atoms / cm 3 Less than 1 x 10 19 atoms / cm 3 less than 5 × 10 18 atoms / cm 3 less than 1×10 18 atoms / cm 3 Make it less than.

[0432] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0433] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification and the like.

[0434] (Sixth embodiment) In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS.

[0435] The electronic devices of this embodiment include the display device of one embodiment of the present invention. The display device of one embodiment of the present invention can easily achieve high definition, high resolution, and a large size. Therefore, the display device of one embodiment of the present invention can be used as a display portion of various electronic devices.

[0436] Furthermore, the display device of one embodiment of the present invention can be manufactured at low cost, which leads to a reduction in the manufacturing cost of electronic devices.

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

[0438] In particular, the display device of one embodiment of the present invention can achieve high resolution and is therefore suitable for use in electronic devices having a relatively small display area. Examples of such electronic devices include information terminals (wearable devices) such as wristwatches and bracelets, as well as head-mounted wearable devices such as VR devices and glasses-type AR devices. Further examples of wearable devices include SR devices and MR devices.

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

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

[0441] The electronic device of this embodiment may have an antenna. By receiving a signal through the antenna, images, information, and the like can be displayed on a display portion. In addition, when 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 a sensor (including the function of sensing, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared light).

[0443] The electronic device of the present embodiment can have various functions, such as a function 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, time, etc., a function to execute various software (programs), a wireless communication function, a function to read out programs or data recorded on a recording medium, etc.

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

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

[0446] The display device of one embodiment of the present invention can be applied to the display portion 6502.

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

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

[0449] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

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

[0451] The flexible display (flexible display device) of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. Furthermore, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

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

[0453] The display device of one embodiment of the present invention can be applied to the display portion 7000.

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

[0455] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. In addition, 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] 23B shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. A display portion 7000 is incorporated in the housing 7211.

[0457] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0458] 23C and 23D show an example of digital signage.

[0459] 23C includes a housing 7301, a display unit 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0460] 23D shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0461] 23C and 23D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0462] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it will attract people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[0463] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000 but also allows the user to intuitively operate it. Furthermore, when used to provide information such as route information or traffic information, intuitive operation can improve usability.

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

[0465] Furthermore, it is also possible to cause the digital signage 7300 or the digital signage 7400 to execute a game using the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller), thereby allowing an unspecified number of users to simultaneously participate in and enjoy the game.

[0466] FIG. 24A is a diagram showing the 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 attached to the camera 8000. Note that the lens 8006 and the housing of the camera 8000 may be integrated together.

[0468] The camera 8000 can capture an image by pressing a shutter button 8004 or touching a display unit 8002 that functions as a touch panel.

[0469] The housing 8001 has a mount with electrodes, and can be connected to a finder 8100 as well as a strobe device and the like.

[0470] The finder 8100 includes a housing 8101, a display portion 8102, a button 8103, and the like.

[0471] The housing 8101 is attached to the camera 8000 by a mount that engages with the mount of the camera 8000. The viewfinder 8100 can display an image received from the camera 8000 on a display unit 8102.

[0472] The button 8103 has a function such as a power button.

[0473] The display device of one embodiment of the present invention can be applied to a display portion 8002 of a camera 8000 and a display portion 8102 of a finder 8100. Note that the camera 8000 may have a built-in finder.

[0474] FIG. 24B is a diagram showing the appearance of the head mounted display 8200.

[0475] The head-mounted display 8200 includes a mounting portion 8201, a lens 8202, a main body 8203, a display portion 8204, and a cable 8205. The mounting portion 8201 has a built-in battery 8206.

[0476] A cable 8205 supplies power from a battery 8206 to the main body 8203. The main body 8203 includes a wireless receiver or the like, and can display received video information on a display portion 8204. The main body 8203 also includes a camera, and can use information on the movement of the user's eyeballs or eyelids as an input means.

[0477] The wearing unit 8201 may have a function of recognizing the line of sight by providing a plurality of electrodes at positions that come into contact with the user, capable of detecting a current that flows in accordance with the movement of the user's eyeballs. The wearing unit 8201 may also have a function of monitoring the user's pulse rate based on the current that flows through the electrodes. The wearing unit 8201 may also have various sensors, such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may also have a function of displaying the user's biological information on the display unit 8204 and a function of changing the image displayed on the display unit 8204 in accordance with the movement of the user's head.

[0478] The display device of one embodiment of the present invention can be applied to the display portion 8204.

[0479] 24C to 24E are diagrams showing the appearance of a head mounted display 8300. The head mounted display 8300 includes a housing 8301, a display portion 8302, a band-shaped fixture 8304, and a pair of lenses 8305.

[0480] A user can view the display on the display portion 8302 through the lens 8305. Note that it is preferable to arrange the display portion 8302 in a curved manner because the user can feel a high sense of presence. In addition, by viewing different images displayed in different regions of the display portion 8302 through the lens 8305, it is possible to perform 3D display using parallax. Note that the present invention is not limited to a configuration in which one display portion 8302 is provided, and two display portions 8302 may be provided, with one display portion being provided for each eye of the user.

[0481] The display device of one embodiment of the present invention can be applied to the display portion 8302. The display device of one embodiment of the present invention can also achieve extremely high resolution. For example, even when the display is enlarged and viewed using the lens 8305 as shown in FIG. 24E, the pixels are hardly visible to the user. That is, the display portion 8302 allows the user to view a highly realistic image.

[0482] 24F is a diagram showing the appearance of a goggle-type head-mounted display 8400. The head-mounted display 8400 includes a pair of housings 8401, a mounting portion 8402, and a cushioning member 8403. A display portion 8404 and a lens 8405 are provided in each of the pair of housings 8401. By displaying different images on the pair of display portions 8404, a 3D display using parallax can be performed.

[0483] A user can view the display portion 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 portion 8404 is preferably a square or a horizontally long rectangle. This can enhance the sense of realism.

[0484] The wearing part 8402 is preferably adjustable to fit the size of the user's face and has plasticity and elasticity to prevent it from slipping off. Furthermore, a part of the wearing part 8402 preferably has a vibration mechanism that functions as a bone conduction earphone. This allows the user to enjoy video and audio simply by wearing the earphone, without the need for separate audio equipment such as earphones or speakers. The housing 8401 may also have a function to output audio data via wireless communication.

[0485] The mounting unit 8402 and the buffer member 8403 are portions that come into contact with the user's face (forehead, cheeks, etc.). The close contact of the buffer member 8403 with the user's face can prevent light leakage and enhance the sense of immersion. The buffer member 8403 is preferably made of a soft material so that it can be in close contact with 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, using a sponge or the like with its surface covered with cloth or leather (natural leather or synthetic leather) can prevent gaps from forming between the user's face and the buffer member 8403, thereby effectively preventing light leakage. Furthermore, using such materials is preferable because they feel pleasant to the touch and do not cause the user to feel cold when worn in cold seasons. It is preferable that components that come into contact with the user's skin, such as the buffer member 8403 or the mounting unit 8402, be removable for easy cleaning or replacement.

[0486] The electronic device shown in Figures 25A to 25F has a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including the function of detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared), a microphone 9008, etc.

[0487] 25A to 25F have various functions. For example, they may have a function 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 using various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. Note that the functions of the electronic device are not limited to these, and the electronic device may have various other functions. The electronic device may have multiple display units. Furthermore, the electronic device may have a function to include a camera or the like to capture still images or videos and store them on a recording medium (external or built-in to the camera), a function to display the captured images on the display unit, etc.

[0488] The display device of one embodiment of the present invention can be applied to the display portion 9001 .

[0489] The electronic devices shown in FIGS. 25A to 25F will be described in detail below.

[0490] FIG. 25A is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 can be used as, for example, a smartphone. Note that the mobile information terminal 9101 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, and the like. The mobile information terminal 9101 can display text and image information on multiple surfaces thereof. FIG. 25A shows an example in which three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notifications of incoming emails, SNS messages, phone calls, etc., the title of the email or SNS message, the sender's name, the date and time, the remaining battery level, and the strength of antenna reception. Alternatively, the icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0491] 25B is a perspective view showing a mobile information terminal 9102. The mobile information terminal 9102 has a 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, while the user holds the mobile information terminal 9102 in a breast pocket of their clothes, the user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9102. The user can check the display without taking the mobile information terminal 9102 out of their pocket and decide, for example, whether to answer a call.

[0492] FIG. 25C is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display unit 9001 is curved, and a display can be performed along the curved display surface. The mobile information terminal 9200 can also perform hands-free communication by communicating with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and reception with another information terminal and charge itself via a connection terminal 9006. Note that charging may be performed by wireless power supply.

[0493] 25D to 25F are perspective views showing a foldable mobile information terminal 9201. FIG. 25D shows the mobile information terminal 9201 in an unfolded state, FIG. 25F shows it in a folded state, and FIG. 25E is a perspective view showing a state in the process of changing from one of FIG. 25D and FIG. 25F to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent viewability of the display. The display unit 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display unit 9001 can be bent with a curvature radius of 0.1 mm or more and 150 mm or less.

[0494] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification and the like. [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 region, 101: insulating film, 102: anode, 104: hole injection layer, 105: hole transport layer, 110x: first region, 110y: second region, 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: connection portion, 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: connection 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 unit, 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 device, 7101: Housing, 7103: Stand, 7111: Remote control device, 7200: Notebook personal computer, 7211: Housing, 7212: Keyboard, 7213: Pointing device, 7214: External connection port, 7300: Digital signage, 7301: Housing, 7303: Speaker, 7311: Information terminal, 7400: Digital signage, 7401: Pillar, 7411: Information terminal, 8000: Camera, 8001: Housing, 8002: Display, 8003: Operation buttons, 8004: Shutter button, 8006: Lens, 8100: Viewfinder, 8101: Housing, 8102: Display, 8103: Button, 820 0: Head-mounted display, 8201: Mounting part, 8202: Lens, 8203: Main body, 8204: Display part, 8205: Cable, 8206: Battery, 8300: Head-mounted display, 8301: Housing, 8302: Display part, 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 part, 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: mobile information terminal, 9102: mobile information terminal, 9200: mobile information terminal, 9201: mobile information terminal,

Claims

1. 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 across the first anode to the third anode; a partition wall provided on the hole injection layer; a first light-emitting layer located in the first opening of the partition wall and overlapping the first anode; a second light-emitting layer located in the second opening of the partition wall and overlapping the second anode; a third light-emitting layer located in the third opening of the partition wall and overlapping with the third anode; a cathode provided across the first light-emitting layer to the third light-emitting layer, The partition wall is a first region located between the first anode and the third anode and extending in the X direction in a top view, 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, a height in the first region is greater than a height in the second region, and a height at the intersection is greater than a height in the first region; the partition wall has a laminated structure in the first region; Display device.

2. 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 across the first anode to the third anode; a partition wall provided on the hole injection layer; a first light-emitting layer located in the first opening of the partition wall and overlapping the first anode; a second light-emitting layer located in the second opening of the partition wall and overlapping the second anode; a third light-emitting layer located in the third opening of the partition wall and overlapping with the third anode; a cathode provided across the first light-emitting layer to the third light-emitting layer, The partition wall is a first region located between the first anode and the third anode and extending in the X direction in a top view, 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, a height in the second region is greater than a height in the first region, and a height at the intersection is greater than a height in the second region; the partition wall has a laminated structure in the second region; Display device.

3. In claim 1 or claim 2, The display device, wherein the partition having the laminated structure includes a first partition having an inorganic material and a second partition having an organic material located on the first partition.

4. In any one of claims 1 to 3, a hole transport layer is provided between the hole injection layer and the partition wall; Display device.

5. In any one of claims 1 to 4, the hole injection layer comprises molybdenum oxide; Display device.

6. In any one of claims 1 to 5, Ends of the first anode to the third anode each have a tapered shape. Display device.

7. 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 anode to the third anode; forming a partition wall on the hole injection layer, the partition wall having a first opening overlapping with the first anode, a second opening overlapping with the second anode, and a third opening overlapping with the third anode; forming any one of a first light-emitting layer located in the first opening, a second light-emitting layer located in the second opening, and a third light-emitting layer located in the third opening by an ink-jet method; A method for manufacturing a display device, comprising forming a cathode across the first light-emitting layer to the third light-emitting layer, The partition wall is a first region located between the first anode and the third anode and extending in the X direction in a top view, 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, a height in the first region is greater than a height in the second region, and a height at the intersection is greater than a height in the first region; the partition wall has a laminated structure in the first region, forming one of the first light-emitting layer and the third light-emitting layer by an ink-jet method while moving along the first region; A method for manufacturing a display device.

8. 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 anode to the third anode; forming a partition wall on the hole injection layer, the partition wall having a first opening overlapping with the first anode, a second opening overlapping with the second anode, and a third opening overlapping with the third anode; forming any one of a first light-emitting layer located in the first opening, a second light-emitting layer located in the second opening, and a third light-emitting layer located in the third opening by an ink-jet method; A method for manufacturing a display device, comprising forming a cathode across the first light-emitting layer to the third light-emitting layer, The partition wall is a first region located between the first anode and the third anode and extending in the X direction in a top view, 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, a height in the second region is greater than a height in the first region, and a height at the intersection is greater than a height in the first region; the partition wall has a laminated structure in the second region, forming one of the first light-emitting layer and the third light-emitting layer by an ink-jet method while moving along the second region; A method for manufacturing a display device.

9. In claim 7 or claim 8, forming a hole transport layer on the hole injection layer; forming the partition wall on the hole transport layer; A method for manufacturing a display device.

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