Display device

Abstract

Provided is a display device in which a voltage drop is suppressed. This display device has: a first lower electrode; a second lower electrode; a third lower electrode; auxiliary electrodes; banks having regions overlapping with an end part of the first lower electrode, an end part of the second lower electrode, an end part of the third lower electrode, and the auxiliary electrodes; a first light-emitting layer having a region overlapping with the first lower electrode and being positioned at a bank opening part; a first layer positioned between the first lower electrode and the first light-emitting layer; a second light-emitting layer having a region overlapping with the second lower electrode and being positioned at a bank opening part; a second layer positioned between the second lower electrode and the second light-emitting layer; a third light-emitting layer having a region overlapping with the third lower electrode and being positioned at a bank opening part; a third layer positioned between the third lower electrode and the third light-emitting layer; and an upper electrode disposed over a region from the first light-emitting layer to the third light-emitting layer, said upper electrode being electrically connected to the auxiliary electrodes.

Description

display device

[0001] One aspect of the present invention relates to a display device.

[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.

[0003] When manufacturing a large-sized organic EL device, a structure in which an auxiliary electrode is provided to suppress a voltage drop in the counter electrode has been considered (see Patent Document 1).

[0004] JP 2005-158583 A

[0005] In the above-mentioned Patent Document 1, aluminum metal covering the top surface of the partition wall (also referred to as a bank) is patterned to form an auxiliary electrode on the partition wall. The same Patent Document 1 also discloses that the auxiliary electrode may be formed by an inkjet method other than the above-mentioned vapor deposition method.

[0006] According to Patent Document 1, the auxiliary electrodes are formed on the upper surfaces of the partition walls, and therefore need to be smaller than the width of the partition walls. Furthermore, the partition walls are becoming smaller as the aperture ratio of display devices increases. For these reasons, it becomes difficult to form auxiliary electrodes on the upper surfaces of the partition walls in display devices with high aperture ratios.

[0007] In view of the above, an object of one embodiment of the present invention is to provide a new structure for an auxiliary electrode in a display device with a high aperture ratio.Furthermore, an object is to provide a display device including the auxiliary electrode and a manufacturing method thereof.

[0008] The description of the above-mentioned problems does not preclude the existence of other problems. Problems other than those mentioned above will become apparent from the description in the specification, drawings, claims, etc., and problems can be extracted from the description in the specification, drawings, claims, etc. Furthermore, one embodiment of the present invention does not necessarily solve all of the above-mentioned problems.

[0009] In view of the above problems, one embodiment of the present invention provides a light-emitting device including: a first lower electrode; a second lower electrode located in a region adjacent to the first lower electrode in the X direction in a top view; a third lower electrode located in a region adjacent to the first lower electrode in the Y direction in a top view; an auxiliary electrode located in a region between at least the first lower electrode and the second lower electrode in a top view; a partition having a region overlapping with an end of the first lower electrode, an end of the second lower electrode, an end of the third lower electrode, and the auxiliary electrode; a first light-emitting layer having a region overlapping with the first lower electrode and located in an opening of the partition; and a first layer located between the first lower electrode and the first light-emitting layer. a second light-emitting layer having a region overlapping with a second lower electrode and positioned in an opening of the partition; a second layer positioned between the second lower electrode and the second light-emitting layer; a third light-emitting layer having a region overlapping with a third lower electrode and positioned in the opening of the partition; a third layer positioned between the third lower electrode and the third light-emitting layer; and an upper electrode provided across the first to third light-emitting layers, wherein the upper electrode is electrically connected to an auxiliary electrode, the first to third layers each have a hole-transport layer or a hole-injection layer, and the partition has a stacked structure of a first insulator containing an inorganic material and a second insulator containing an organic material.

[0010] Another aspect of the present invention is a semiconductor device including: a first lower electrode; a second lower electrode located in a region adjacent to the first lower electrode in the X direction in a top view; a third lower electrode located in a region adjacent to the first lower electrode in the Y direction in a top view; an auxiliary electrode located at least between the first lower electrode and the second lower electrode in a top view; a partition having an area overlapping with an end of the first lower electrode, an end of the second lower electrode, an end of the third lower electrode, and the auxiliary electrode; a first light-emitting layer having an area overlapping with the first lower electrode and located at an opening of the partition; a first layer located between the first lower electrode and the first light-emitting layer; a second light-emitting layer having an area overlapping with the second lower electrode and located at the opening of the partition; a second layer located between the second lower electrode and the second light-emitting layer; a third light-emitting layer having a region overlapping with the lower electrode and positioned in an opening of the partition; a third layer positioned between the third lower electrode and the third light-emitting layer; and an upper electrode provided across the first to third light-emitting layers, wherein the upper electrode is electrically connected to an auxiliary electrode through a contact hole positioned at least between the first lower electrode and the second lower electrode; each of the first to third layers has a hole-transport layer or a hole-injection layer; the partition has a stacked structure of a first insulator containing an inorganic material and a second insulator containing an organic material; the contact hole has a first opening included in the first insulator and a second opening included in the second insulator; and the first insulator has an end exposed from the second opening in a top view of the contact hole.

[0011] Another aspect of the present invention is a semiconductor device including: a first lower electrode; a second lower electrode located in a region adjacent to the first lower electrode in the X direction in a top view; a third lower electrode located in a region adjacent to the first lower electrode in the Y direction in a top view; an auxiliary electrode located at least between the first lower electrode and the second lower electrode in a top view; a partition wall having an area overlapping with an end of the first lower electrode, an end of the second lower electrode, an end of the third lower electrode, and the auxiliary electrode; a first light-emitting layer having an area overlapping with the first lower electrode and located in an opening of the partition wall; a first layer located between the first lower electrode and the first light-emitting layer; and a second lower electrode. a second light-emitting layer having a region overlapping with the third lower electrode and positioned at an opening of the partition; a second layer positioned between the second lower electrode and the second light-emitting layer; a third light-emitting layer having a region overlapping with the third lower electrode and positioned at the opening of the partition; a third layer positioned between the third lower electrode and the third light-emitting layer; and an upper electrode provided over the first to third light-emitting layers, wherein the upper electrode is electrically connected to an auxiliary electrode via a conductive layer, the first to third layers each include a hole-transport layer or a hole-injection layer, and the partition has a stacked structure of a first insulator containing an inorganic material and a second insulator containing an organic material.

[0012] Another embodiment of the present invention relates to a semiconductor device including: a first lower electrode; a second lower electrode located in a region adjacent to the first lower electrode in the X direction in a top view; a third lower electrode located in a region adjacent to the first lower electrode in the Y direction in a top view; an auxiliary electrode located between at least the first lower electrode and the second lower electrode in a top view; a partition having an area overlapping with an end portion of the first lower electrode, an end portion of the second lower electrode, an end portion of the third lower electrode, and the auxiliary electrode; a first light-emitting layer having an area overlapping with the first lower electrode and located at an opening of the partition; a first layer located between the first lower electrode and the first light-emitting layer; a second light-emitting layer having an area overlapping with the second lower electrode and located at the opening of the partition; a second layer located between the second lower electrode and the second light-emitting layer; and a second layer having an area overlapping with the third lower electrode and located at the opening of the partition. a third light-emitting layer located in an opening portion, a third layer located between the third lower electrode and the third light-emitting layer, and an upper electrode provided across the first to third light-emitting layers, the upper electrode being electrically connected to an auxiliary electrode through a contact hole located at least between the first lower electrode and the second lower electrode, the first to third layers each having a hole-transporting layer or a hole-injecting layer, the partition wall having a stacked structure of a first insulator containing an inorganic material and a second insulator containing an organic material, the contact hole having a first opening in the first insulator and a second opening in the second insulator, the first insulator having an end exposed from the second opening in a top view of the contact hole, and the upper electrode being electrically connected to the auxiliary electrode through a conductive layer exposed from the first opening.

[0013] In another aspect of the present invention, the height of the partition walls along the X direction is preferably smaller than the height of the partition walls along the Y direction.

[0014] According to one embodiment of the present invention, a display device including an auxiliary electrode and a manufacturing method thereof can be provided, and a voltage drop due to an upper electrode can be suppressed.

[0015] The description of the above effects does not preclude the existence of other effects. Effects other than those described above will become apparent from the description in the specification, drawings, claims, etc., and the effects can be extracted from the description in the specification, drawings, claims, etc. Furthermore, one embodiment of the present invention does not necessarily have all of the above effects.

[0016] FIG. 1A is a top view showing a pixel region of one embodiment of the present invention, and FIGS. 1B1, 1B2, and 1C are cross-sectional views showing the pixel region. FIGS. 2A to 2D are cross-sectional views showing examples of transistor configurations. FIG. 3 is a cross-sectional view showing a pixel region of one embodiment of the present invention. FIGS. 4A and 4B are cross-sectional views showing a method for forming a pixel region by an inkjet method of one embodiment of the present invention. FIGS. 5A and 5B are cross-sectional views showing a method for forming a pixel region by an evaporation method of one embodiment of the present invention. FIG. 6 is a perspective view showing a pixel region of one embodiment of the present invention. FIG. 7A is a cross-sectional view showing a method for forming a pixel region by an inkjet method of one embodiment of the present invention, and FIG. 7B is a cross-sectional view showing a method for forming a pixel region by an evaporation method of one embodiment of the present invention. FIG. 8A is a top view showing a pixel region of one embodiment of the present invention, and FIGS. 8B and 8C are cross-sectional views showing the pixel region. FIG. 9 is a cross-sectional view showing a pixel region of one embodiment of the present invention. FIGS. 10A and 10B are cross-sectional views showing a method for forming a pixel region by an inkjet method of one embodiment of the present invention. FIGS. 11A and 11B are cross-sectional views showing a method for forming a pixel region by an evaporation method of one embodiment of the present invention. FIG. 12A is a cross-sectional view illustrating a method for forming a pixel region using an inkjet method according to one embodiment of the present invention, and FIG. 12B is a cross-sectional view illustrating a method for forming a pixel region using a vapor deposition method according to one embodiment of the present invention. FIG. 13A is a top view illustrating a pixel region according to one embodiment of the present invention, and FIGS. 13B and 13C are cross-sectional views illustrating the pixel region. FIG. 14 is a cross-sectional view illustrating a pixel region according to one embodiment of the present invention. FIGS. 15A and 15B are cross-sectional views illustrating a method for forming a pixel region using an inkjet method according to one embodiment of the present invention. FIGS. 16A and 16B are cross-sectional views illustrating a method for forming a pixel region using a vapor deposition method according to one embodiment of the present invention. FIG. 17 is a perspective view illustrating a pixel region according to one embodiment of the present invention. FIG. 18A is a cross-sectional view illustrating a method for forming a pixel region using an inkjet method according to one embodiment of the present invention, and FIG. 18B is a cross-sectional view illustrating a method for forming a pixel region using a vapor deposition method according to one embodiment of the present invention. FIG. 19A is a top view illustrating a pixel region according to one embodiment of the present invention, and FIGS. 19B and 19C are cross-sectional views illustrating the pixel region. FIG. 20 is a cross-sectional view illustrating a pixel region according to one embodiment of the present invention. 21A and 21B are cross-sectional views illustrating a method for manufacturing a pixel region by an inkjet method according to one embodiment of the present invention.FIGS. 22A and 22B are cross-sectional views illustrating a method for fabricating a pixel region by a vapor deposition method according to one embodiment of the present invention. FIG. 23A is a cross-sectional view illustrating a method for fabricating a pixel region by an inkjet method according to one embodiment of the present invention, and FIG. 23B is a cross-sectional view illustrating a method for fabricating a pixel region by a vapor deposition method according to one embodiment of the present invention. FIGS. 24A to 24D2 are cross-sectional views illustrating a light-emitting device according to one embodiment of the present invention. FIGS. 25A to 25D are circuit diagrams illustrating a pixel circuit according to one embodiment of the present invention. FIGS. 26A to 26D are circuit diagrams illustrating a pixel circuit according to one embodiment of the present invention. FIGS. 27A and 27B are circuit diagrams illustrating a pixel circuit according to one embodiment of the present invention. FIGS. 28A and 28B are circuit diagrams illustrating a pixel circuit according to one embodiment of the present invention. FIG. 29 is a diagram illustrating a method for driving a pixel circuit according to one embodiment of the present invention. FIG. 30 is a perspective view illustrating a display device according to one embodiment of the present invention. FIG. 31A is a cross-sectional view illustrating a display device according to one embodiment of the present invention, and FIG. 31B is a cross-sectional view illustrating a transistor according to one embodiment of the present invention. FIG. 32 is a cross-sectional view illustrating a display device according to one embodiment of the present invention. FIG. 33 is a cross-sectional view illustrating a display device according to one embodiment of the present invention. FIG. 34A is a cross-sectional view of a display device of one embodiment of the present invention, and FIG. 34B is a cross-sectional view of a transistor of one embodiment of the present invention. FIG. 35 is a cross-sectional view of a display device of one embodiment of the present invention. FIG. 36 is a cross-sectional view of a display device of one embodiment of the present invention. FIGS. 37A and 37B are diagrams showing electronic devices of one embodiment of the present invention. FIGS. 38A to 38D are diagrams showing electronic devices of one embodiment of the present invention. FIGS. 39A to 39F are diagrams showing electronic devices of one embodiment of the present invention. FIGS. 40A to 40F are diagrams showing electronic devices of one embodiment of the present invention.

[0017] In this specification, the configuration may be classified by function and explained using block diagrams that are independent of each other, but in reality it is difficult to separate the configuration by function, and one configuration may be involved in multiple functions.

[0018] In this specification and the like, the names of the source and drain of a transistor are interchanged depending on the polarity of the transistor and the level of the potential applied to each terminal. Generally, in an n-channel transistor, the terminal to which a low potential is applied is called the source, and the terminal to which a high potential is applied is called the drain. In addition, in a p-channel transistor, the terminal to which a low potential is applied is called the drain, and the terminal to which a high potential is applied is called the source. In practice, the names of the source and the drain may be interchanged depending on the above-mentioned potential relationship, but in this specification and the like, when describing the connection relationship of a transistor, the source and the drain are fixed for convenience.

[0019] In this specification, the source of a transistor refers to the source region of a semiconductor layer that functions as an active layer or the source electrode connected to the semiconductor layer. Similarly, the drain of a transistor refers to the drain region of the semiconductor layer or the drain electrode connected to the semiconductor layer. Furthermore, the gate of a transistor refers to the gate electrode.

[0020] 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.

[0021] In this specification, connection may be referred to as electrical connection, and includes a state in which a current, voltage, or potential can be supplied or transmitted. Therefore, it also includes a state in which things are connected to each other via elements such as wiring, resistors, diodes, and transistors. Electrical connection also includes a state in which things are directly connected to each other without using elements such as wiring, resistors, diodes, and transistors.

[0022] In this specification and the like, a conductive layer may have multiple functions such as wiring and electrode. When it is described in this specification and the like that a wiring is connected to an electrode, this also includes the case where there is one conductive layer having both of the above-mentioned functions.

[0023] In this specification and the like, the source and drain of a transistor may be described using a first electrode and a second electrode; however, when one of the first electrode and the second electrode is the source, the other is the drain.

[0024] In this specification and the like, a light-emitting device may be referred to as a light-emitting element.

[0025] In this specification, a light-emitting device in which a light-emitting layer is formed using a metal mask (MM) may be referred to as a light-emitting device having a metal mask (MM) structure. As the openings of a metal mask become finer, the metal mask may be referred to as a fine metal mask (FMM, high-definition metal mask). Furthermore, in this specification, a light-emitting device in which a light-emitting layer is formed without using a metal mask or a fine metal mask may be referred to as a light-emitting device having a metal maskless (MML) structure.

[0026] In this specification and the like, a structure in which light-emitting layers of each color (for example, red (R), green (G), and blue (B)) are painted differently may be referred to as an SBS (Side By Side) structure. Furthermore, in this specification and the like, a light-emitting device capable of emitting white light may be referred to as a white light-emitting device. A white light-emitting device can be combined with a colored layer (for example, a color filter) to form a full-color display device.

[0027] Light-emitting devices can be broadly divided into single structures and tandem structures. A single structure has one light-emitting unit between a pair of electrodes, and the light-emitting unit preferably includes one or more light-emitting layers. Therefore, the light-emitting unit is sometimes referred to as an EL layer. In a single structure, white light emission can be achieved by ensuring that the light emitted by two or more light-emitting layers has a complementary color relationship. For example, by ensuring that the light emitted by the first light-emitting layer and the light emitted by the second light-emitting layer have a complementary color relationship, a configuration in which the entire light-emitting device emits white light can be achieved. Furthermore, in the case of a light-emitting device having three or more light-emitting layers, a configuration in which white light emission can be achieved by ensuring the complementary color relationship.

[0028] The tandem structure preferably has two or more light-emitting units between a pair of electrodes, and each light-emitting unit preferably includes one or more light-emitting layers. In the tandem structure, it is preferable to provide an intermediate layer such as a charge generating layer between the plurality of light-emitting units. In order to obtain white light emission in the tandem structure, a structure may be used in which light from the light-emitting layers of two or more light-emitting units is combined to obtain white light emission. Note that, as with the single structure, the structure that obtains white light emission only needs to satisfy a complementary color relationship.

[0029] Furthermore, when comparing the above-described white light-emitting device (single structure or tandem structure) with a light-emitting device having an SBS structure, the light-emitting device having an SBS structure can reduce power consumption compared to the white light-emitting device. If it is desired to reduce power consumption, it is preferable to use a light-emitting device having an SBS structure. On the other hand, the manufacturing process of a white light-emitting device is simpler than that of a light-emitting device having an SBS structure, and therefore the manufacturing cost can be reduced or the manufacturing yield can be increased, making it preferable.

[0030] Next, the 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.

[0031] Embodiment 1 In this embodiment, a pixel region having an auxiliary electrode in a display device according to one embodiment of the present invention will be described.

[0032] As shown in the top view (also referred to as a plan view) of Figure 1A, a pixel region 10 of the display device has a plurality of pixels. A pixel has at least a light-emitting device and is the smallest unit capable of emitting one emitted color. Such a pixel may be referred to as a subpixel.

[0033] A light-emitting device has a pair of electrodes and a layer (referred to as an organic material layer or organic compound layer) between them, which contains an organic material, such as a light-emitting layer. In terms of the stacking order of a light-emitting device, one of the pair of electrodes can be referred to as the upper electrode, and the other as the lower electrode. The organic material layer or organic compound layer is a stack of functional layers, such as a light-emitting layer, and may be referred to as a light-emitting unit or EL layer, which can be located between the pair of electrodes. Because organic compounds are often used as functional layers, they are referred to as organic material layers or organic compound layers. However, at least one functional layer may be a layer containing an inorganic material (referred to as an inorganic material layer or inorganic compound layer). In addition to the light-emitting layer, functional layers include carrier injection layers (hole injection layers and electron injection layers) and carrier transport layers (hole transport layers and electron transport layers). A hole injection layer refers to a layer containing a substance with high hole injection properties. An electron injection layer refers to a layer containing a substance with high electron injection properties. A hole transport layer refers to a layer containing a substance with high hole transport properties. An electron transport layer refers to a layer containing a substance with high electron transport properties.

[0034] 1A illustrates an example in which a pixel region 10 includes a pixel 11R capable of exhibiting red, a pixel 11G capable of exhibiting green, and a pixel 11B capable of exhibiting blue. Ordinal numbers may be assigned to distinguish the pixels, and the pixels may be referred to as a first red pixel, a second red pixel, and so on.

[0035] 1A , the pixel region 10 may be described using the X direction and the Y direction intersecting the X direction. For example, in the pixel region 10, the pixel 11R, the pixel 11G, and the pixel 11B are arranged in order in the X direction, and multiple pixels 11R are arranged in the Y direction. Similarly, multiple pixels 11B and 11G are arranged in the Y direction. In addition, in the pixel region 10, the pixel 11G is located in a region adjacent to the pixel 11R in the X direction, and another pixel 11R is located in a region adjacent to the pixel 11R in the Y direction.

[0036] Pixel 11R has at least a contact hole 15R. Contact hole 15R is an opening provided in an insulating layer located between a light-emitting device and a transistor that drives the light-emitting device to ensure electrical connection between the light-emitting device and the transistor. Similarly, pixel 11G has at least a contact hole 15G, and pixel 11B has at least a contact hole 15B.

[0037] As shown in FIG. 1A , the pixel region 10 includes an auxiliary electrode 115. The auxiliary electrode is a layer that functions as an auxiliary to the main electrode, and this auxiliary function includes reducing the resistance of the main electrode. To reduce the resistance of the main electrode, the auxiliary electrode is formed using at least a conductive material. Furthermore, it is preferable that the resistivity of the conductive material of the auxiliary electrode be lower than that of the conductive material of the main electrode. When the auxiliary electrode has a layered structure, it is preferable to use a conductive material with a lower resistivity than that of the conductive material of the main electrode in at least one layer. However, the above resistivity relationship is not essential, since the auxiliary electrode can also reduce the resistance of the main electrode by making the area of ​​the auxiliary electrode larger than that of the main electrode or by making the thickness of the auxiliary electrode thicker than that of the main electrode. Although the auxiliary electrode is sometimes referred to as an auxiliary wiring based on its shape, this specification and the like will use the auxiliary electrode as an example.

[0038] 1A shows a case where the auxiliary electrodes 115 are arranged between the pixels in the pixel region 10. The auxiliary electrodes 115 have regions extending in the X and Y directions, and appear in a grid pattern when viewed from above. However, the arrangement of the auxiliary electrodes is not limited to the grid pattern as long as they are arranged to reduce the resistance of the main electrodes.

[0039] The pixel region 10 has a contact hole 18. The contact hole 18 is an opening provided in an insulating layer located between the auxiliary electrode 115 and the upper electrode 159 in order to ensure electrical connection between the auxiliary electrode 115 and the upper electrode 159 of the light-emitting device. The upper electrode 159 will be described later. The top surface shape of the contact hole 18 is preferably larger than the contact holes 15R and the like of each pixel, and if it is circular, for example, the diameter should be longer.

[0040] 1B1 shows a cross-sectional view corresponding to A1-A2 passing through contact holes 15R, 15G, and 15B in FIG. 1A. FIG. 1C shows a cross-sectional view corresponding to B1-B2 passing through contact hole 18 in FIG. 1A.

[0041] 1B1 and 1C show an example in which a transistor 101 is provided over a substrate 100. The transistor 101 is an element (referred to as a driving element) for driving a light-emitting device. A display device having such a driving element in each pixel is referred to as an active matrix display device.

[0042] 1B1 illustrates a top-gate transistor in which the gate 102 is located above the semiconductor layer as the transistor 101. Of course, in the present invention, a bottom-gate transistor in which the gate is located below the semiconductor layer, or a dual-gate transistor in which the gate is located above and below the semiconductor layer may also be applied.

[0043] A gate insulating layer is located between the gate 102 and the semiconductor layer. The semiconductor layer can be formed using silicon or an oxide semiconductor, and may be crystalline or amorphous. When the semiconductor layer is formed using silicon, the regions in contact with the source and drain 103 are called impurity regions, and elements other than silicon, such as phosphorus or boron (referred to as impurity elements), are added to reduce resistance (the impurity regions are also referred to as low-resistance regions).

[0044] The source and drain 103 can have a single-layer structure of a conductive layer or a stacked structure of conductive layers. The conductive layer contains a conductive material, such as aluminum, titanium, copper, tungsten, molybdenum, or nickel. In the case of a stacked structure, a conductive layer containing titanium, a conductive layer containing aluminum, and a conductive layer containing titanium are preferably used.

[0045] The gate 102 can have a single-layer structure of a conductive layer or a stacked structure of conductive layers. The conductive layer contains a conductive material, such as aluminum, titanium, copper, tungsten, molybdenum, or nickel. In the case of a stacked structure, a conductive layer containing molybdenum and a conductive layer containing tungsten are preferably used.

[0046] The gate 102 is covered with at least an insulating layer 105. The source and drain 103 can each have a region in contact with the semiconductor layer through an opening provided in the gate insulating layer and an opening provided in the insulating layer 105. Note that in FIG. 1C , it can be seen that one of the source and drain 103 is in contact with the semiconductor layer.

[0047] The gate insulating layer and the insulating layer 105 preferably contain an inorganic material, which can prevent impurity elements from entering the semiconductor layer.

[0048] The inorganic material may be 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 impurity elements such as lanthanum (La), nitrogen, and zirconium (Zr) may be added to the above materials.

[0049] An insulating layer 106 is provided on the insulating layer 105. The upper surface of the insulating layer 106 preferably has flatness because it corresponds to a surface on which a lower electrode of a light-emitting device to be formed later will be formed. For example, the insulating layer 106 can be provided with the above flatness by forming it using an organic material.

[0050] The organic material may be an organic resin such as polyimide resin, polyamide resin, acrylic resin, siloxane resin, silicone resin, epoxy resin, or phenol resin. Note that impurity elements such as lanthanum, nitrogen, or zirconium may be added to the above materials.

[0051] [Application Example of Transistor] An example of a cross-sectional structure of a transistor that can be applied to the transistor 101 will be described.

[0052] 2A is a cross-sectional view including a transistor 101. The transistor 101 is provided over a substrate 100 and can be a transistor in which polycrystalline silicon, which is silicon and has crystallinity, is used for a semiconductor layer. In this case, the transistor 101 can be called an LTPS transistor.

[0053] The transistor 101 includes a semiconductor layer 311, an insulating layer 312, a conductive layer 313, and the like. The semiconductor layer 311 includes a channel formation region 311i and a low-resistance region 311n. At least the channel formation region 311i contains silicon, preferably polycrystalline silicon. A part of the insulating layer 312 functions as a gate insulating layer. A region of the conductive layer 313 that overlaps with the semiconductor layer 311 functions as a gate.

[0054] Note that the semiconductor layer 311 can also be formed using an oxide semiconductor (also referred to as a metal oxide exhibiting semiconductor characteristics). The transistor 101 is a transistor in which at least a channel formation region contains an oxide semiconductor. In this case, the transistor 101 can be called an OS transistor, and the semiconductor layer may be referred to as an oxide semiconductor layer.

[0055] The transistor 101 includes a conductive layer 314a, a conductive layer 314b, and the like. The conductive layer 314a can function as one of a source and a drain, and the conductive layer 314b can function as one of a source and a drain. One of the source and the drain of the transistor 101 can be electrically connected to a lower electrode 116 of the light-emitting device. In FIG. 2A , one of the conductive layers 314a and 314b can be electrically connected to the lower electrode 116 described later, and a contact hole can be formed in, for example, an insulating layer 323 located between them.

[0056] An insulating layer 321 may be provided between the substrate 100 and the transistor 101, and in Fig. 2A, the semiconductor layer 311 is provided on the insulating layer 321. The other configurations can be the same as those described with reference to Fig. 1.

[0057] 2B shows a transistor 101a having a pair of gates. The transistor 101a shown in FIG. 2B differs from the transistor 101a shown in FIG. 2A mainly in that it includes a conductive layer 315 and an insulating layer 316.

[0058] The conductive layer 315 is provided over the insulating layer 321. An insulating layer 316 is provided to cover the conductive layer 315 and the insulating layer 321. The semiconductor layer 311 is provided so that at least a channel formation region 3111 overlaps with the conductive layer 315 with the insulating layer 316 interposed therebetween.

[0059] 2B, part of the conductive layer 313 functions as a first gate, part of the conductive layer 315 functions as a second gate, part of the insulating layer 312 functions as a first gate insulating layer, and part of the insulating layer 316 functions as a second gate insulating layer.

[0060] Here, when the first gate and the second gate are electrically connected, the conductive layer 313 and the conductive layer 315 may be electrically connected through openings provided in the insulating layer 312 and the insulating layer 316 in a region not shown. When the second gate and the source or drain are electrically connected, the conductive layer 314a or the conductive layer 314b may be electrically connected to the conductive layer 315 through openings provided in the insulating layer 322, the insulating layer 312, and the insulating layer 316 in a region not shown.

[0061] In the transistor 101a, the conductive layer 314a can function as one of the source and the drain, and the conductive layer 314b can function as one of the source and the drain. One of the source and the drain of the transistor 101 can be electrically connected to the lower electrode 116 of the light-emitting device. In FIG. 2B , one of the conductive layers 314a and 314b can be electrically connected to the lower electrode 116 described later, and a contact hole can be formed in, for example, the insulating layer 323 located between them.

[0062] 1, when an LTPS transistor is used as the transistor for the pixel 11R or the like, the transistor 101 illustrated in FIG. 2A or the transistor 101a illustrated in FIG. 2B can be used. When an OS transistor is used as the transistor for the pixel 11R or the like, the transistor 101 illustrated in FIG. 2A or the transistor 101a illustrated in FIG. 2B can be used.

[0063] 1, a plurality of transistors may be provided in the pixel 11R or the like, and the transistor 101 and the transistor 101a may be combined in the pixel, for example, by using the transistor 101 as one of the plurality of transistors and the transistor 101a as the other of the plurality of transistors. For example, the transistor 101 may be an LTPS transistor, and the transistor 101a may be an OS transistor. FIG. 2C illustrates a cross-sectional view including a plurality of transistors.

[0064] FIG. 2C shows a cross-sectional view including transistor 101a and transistor 350. Transistor 101a is shown on the right side of FIG. 2C, and an LTPS transistor can be used for the transistor 101a. Transistor 350 is shown on the left side of FIG. 2C, and an OS transistor can be used for the transistor 350. Both transistor 101a and transistor 350 have a pair of gates, but the positions of some of the gates are different.

[0065] Transistor 101a has an insulating layer 326 not shown in FIG. 2B, and the other configurations can refer to the description of FIG. 2B. Also in the transistor 101a shown in FIG. 2C, one of the conductive layers 314a and 314b can be electrically connected to the lower electrode 116, and a contact hole can be formed in, for example, the insulating layer 323 located therebetween.

[0066] Transistor 350 has a conductive layer 355, an insulating layer 322, a semiconductor layer 351, an insulating layer 352, a conductive layer 353, etc. A part of the conductive layer 353 functions as the first gate of the transistor 350, and a part of the conductive layer 355 functions as the second gate of the transistor 350. At this time, a part of the insulating layer 352 functions as the first gate insulating layer of the transistor 350, and a part of the insulating layer 322 functions as the second gate insulating layer of the transistor 350.

[0067] The conductive layer 355 is provided on the insulating layer 312. The insulating layer 322 is provided to cover the conductive layer 355. The semiconductor layer 351 is provided on the insulating layer 322. The insulating layer 352 is provided to cover the semiconductor layer 351 and the insulating layer 322. The conductive layer 353 is provided on the insulating layer 352 and has a region overlapping the semiconductor layer 351 and the conductive layer 355.

[0068] An insulating layer 326 is provided to cover the insulating layer 352 and the conductive layer 353. A conductive layer 354a and a conductive layer 354b are provided over the insulating layer 326. The conductive layer 354a and the conductive layer 354b are electrically connected to the semiconductor layer 351 through openings provided in the insulating layer 326 and the insulating layer 352. The conductive layer 354a functions as one of a source and a drain, and the conductive layer 354b functions as the other of the source and the drain. An insulating layer 323 is provided to cover the conductive layer 354a, the conductive layer 354b, and the insulating layer 326.

[0069] Here, the conductive layers 314a and 314b of the transistor 101a are preferably formed by processing the same conductive film as the conductive layers 354a and 354b. Figure 2C illustrates a configuration in which the conductive layers 314a, 314b, 354a, and 354b are formed on the same surface (specifically, the top surface of the insulating layer 326) and contain the same metal element. In this case, the conductive layers 314a and 314b can be electrically connected to the low-resistance region 311n through contact holes provided in the insulating layer 326, the insulating layer 352, the insulating layer 322, and the insulating layer 312. This is preferable because it simplifies the manufacturing process.

[0070] The conductive layer 313 functioning as the first gate of the transistor 101a and the conductive layer 355 functioning as the second gate of the transistor 350 are preferably formed by processing the same conductive film. In Figure 2C, the conductive layer 313 and the conductive layer 355 are formed on the same surface to be formed (specifically, the top surface of the insulating layer 312) and contain the same metal element. This is preferable because it simplifies the manufacturing process.

[0071] In FIG. 2C , the insulating layer 352 functioning as the first gate insulating layer of the transistor 350 covers the semiconductor layer 351. However, as in the transistor 350 a shown in FIG. 2D , the insulating layer 352 may be processed so that the top surface shape thereof is approximately the same as that of the conductive layer 353.

[0072] <Lower Electrode 116> As shown in FIG. 1B1 and other figures, a lower electrode 116 is formed on the insulating layer 106. The lower electrode 116 corresponds to the lower electrode of a pair of electrodes in the light-emitting device and functions, for example, as an anode. The lower electrode 116 is located on the transistor 101 side and is electrically connected to the transistor 101, allowing signals to be sent from the transistor 101 to the light-emitting device. Because the signals are different for each pixel, the lower electrodes 116 are processed to be independent for each pixel. This processing is sometimes referred to as patterning. The pixel 11R, pixel 11G, and pixel 11B each have a lower electrode 116, and ordinal numbers may be assigned to distinguish the respective lower electrodes 116, such as a first lower electrode and a second lower electrode. The lower electrodes 116 may also be referred to as pixel electrodes.

[0073] The top surface shape of the lower electrode 116 is not limited, but in FIG. 1A, the lower electrode 116 has a rectangular shape with short sides along the X direction and long sides along the Y direction.

[0074] The cross-sectional shape of the lower electrode 116 is not limited, but the end portion may have a tapered shape. In this specification, a tapered shape refers to a shape in which at least a portion of the side surface of a structure is inclined relative to the surface on which the structure is to be formed or the substrate surface. For example, the angle between the inclined side surface and the substrate surface is referred to as the taper angle, and a tapered shape refers to a region in which the taper angle is less than 90°. The side surface of the structure may be substantially planar with a slight curvature or a slight unevenness. The taper angle can also be measured by drawing a line extending from the top to the bottom of the side surface of the structure. Similarly, the surface on which the structure is to be formed or the substrate surface may be substantially planar with a slight curvature or a slight unevenness. The taper angle of the end portion of the lower electrode 116 is preferably 35 degrees or more but less than 90 degrees, and more preferably 40 degrees or more but less than 80 degrees.

[0075] Since the lower electrode 116 is electrically connected to the transistor 101, the insulating layer between them has openings that function as contact holes. For example, in FIG. 1B1 , openings formed in the insulating layer 106 are contact holes 15R, 15G, and 15B, respectively. Each contact hole has a region where one of the source and drain 103 contacts the lower electrode 116. However, as long as electrical connection is achieved via the contact hole, for example, another conductive layer may be interposed between one of the source and drain 103 and the lower electrode 116. In other words, a structure in which one of the source and drain 103 and the lower electrode 116 do not contact each other is also possible.

[0076] Since the lower electrode 116 functions as an anode, it is preferable to use a material with a high work function. Therefore, the lower electrode 116 can be formed using a single-layer structure such as an ITO film (an oxide film containing indium and tin), an indium tin oxide film containing silicon, an indium oxide film containing 2 wt % to 20 wt % zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, a Cu film, or an Al film. It can also be formed using a stacked structure of a titanium nitride film and a film primarily composed of aluminum, or a stacked structure of a titanium nitride film, a film primarily composed of aluminum, and another titanium nitride film. The aluminum-based film may contain nickel, tungsten, or a rare earth element (e.g., lanthanum) in addition to aluminum. When using such a stacked structure, it is preferable to use a low-resistance material for one layer and a material that can form a good ohmic contact with one of the source and drain electrodes 103 for the other layer. The overall thickness of the lower electrode 116 is preferably 100 nm to 250 nm.

[0077] In the case of a display device in which light from a light-emitting device is extracted from the side of the lower electrode 116, the lower electrode 116 needs to have light-transmitting properties. To have light-transmitting properties, a light-transmitting material is selected from the above-mentioned materials, or when a non-light-transmitting material is selected, a structure such as a thin film is adopted.

[0078] <Auxiliary electrode 115> The auxiliary electrode 115 is formed using the same material as the lower electrode 116. In FIGS. 1B1 and 1C, the auxiliary electrode 115 is provided on the insulating layer 106 on which the lower electrode 116 is provided. The auxiliary electrode 115 is processed so as not to have the same potential as the lower electrode 116, that is, it is necessary to make them independent of each other. FIG. 1A shows an example in which they are arranged independent of each other. The auxiliary electrode 115 is arranged in a shape having regions extending in the X direction and the Y direction, that is, in a lattice pattern, utilizing the spaces between the pixels 11R, 11G, and 11B. The distance between the lower electrode 116 and the auxiliary electrode 115 in the region along the Y direction is preferably greater than the distance between the lower electrode 116 and the auxiliary electrode 115 in the region along the X direction.

[0079] The auxiliary electrode 115 enables electrical connection with an upper electrode 159 of a light-emitting device to be formed later. The auxiliary electrode 115 can reduce the resistance of the upper electrode 159, thereby suppressing voltage drop.

[0080] <Partition Wall 110> When one of the organic material layers or organic compound layers, for example, a light-emitting layer, is applied separately by a wet method, such as an inkjet method, a partition into which a solution is dropped is required. The partition can be formed using an insulator, and such an insulator may be referred to as a partition wall, embankment, or bank. When each light-emitting layer is formed by a vapor deposition method, the insulator may have the function of holding a metal mask, specifically a fine metal mask.

[0081] The wet method involves dissolving or dispersing a material having a predetermined function in a solvent to obtain a liquid composition, which is then applied. Examples of materials having a predetermined function include hole injection materials, hole transport materials, light-emitting materials, electron transport materials, and electron injection materials. The liquid composition may also be referred to as droplets or ink material. After application, the liquid composition is solidified or thinned through a drying or curing process to obtain the organic material layer or organic compound layer. When the liquid composition is solidified or thinned, each material becomes a hole injection layer, hole transport layer, light-emitting layer, electron transport layer, or electron injection layer.

[0082] In the inkjet method or spin coating method, the liquid composition is often referred to as droplets, but the liquid composition may also be referred to as ink material. Also, although droplets are sometimes referred to as being dropped, they may also be referred to as applying the ink material.

[0083] Wet methods include inkjet printing, spin coating, coating, inkjet nozzle printing, gravure printing, and the like.

[0084] Examples of solvents that can be used in forming these films using wet processes 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. The solvent can be one or more of the above-mentioned materials.

[0085] The material formed by the inkjet method preferably contains a polymer material (sometimes referred to as a polymer organic material). In particular, a polymer material containing a light-emitting material may be referred to as a polymer light-emitting organic material. Polymer materials are preferred because they are easily mixed with solvents. Among the above-mentioned solvents, those that are easily mixed with polymer materials include toluene and xylene.

[0086] 1B1 and 1C, the partition wall 110 is formed on the lower electrode 116 and the auxiliary electrode 115. Note that the partition wall is omitted in FIG. 1A.

[0087] 1B1, the partition 110 covers the edge of the lower electrode 116 and has an opening that exposes the center of the lower electrode 116. In FIG. 1B1, it can be seen that the partition 110 covers the entire auxiliary electrode 115. In FIG. 1C, a contact hole 18 formed in the partition 110 can be seen, since the auxiliary electrode 115 is electrically connected to the upper electrode.

[0088] In one embodiment of the present invention, the partition 110 preferably has a stacked structure including a first partition (referred to as a first insulator) 120 and a second partition (referred to as a second insulator) 121. The first insulator 120 preferably contains an inorganic material, and the second insulator 121 preferably contains an organic material. Using an organic material for the second insulator 121 is preferable because the partition 110 can be made tall. To make the partition 110 taller, the first insulator 120 may also contain an organic material. An inkjet device can be moved along the tall partition 110. Furthermore, when a light-emitting layer is formed by an inkjet method, the tall partition 110 can suppress color mixing with different color materials.

[0089] The inorganic material of the partition wall 110 may include 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. When the partition wall 110 has a stacked structure, the first insulator 120 or the second insulator 121 may include any of the above inorganic materials.

[0090] The organic material of the partition 110 may be 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. When the partition 110 has a layered structure, the second insulator 121 may contain the above organic material. When the partition 110 is to be made higher, the first insulator 120 may contain the above organic material.

[0091] It is also possible to use materials obtained by adding impurity elements such as lanthanum (La), nitrogen, or zirconium (Zr) to the above inorganic or organic materials.

[0092] The partition walls 110 are configured to separate the pixels when viewed from above the pixel region 10, that is, have a lattice shape having regions extending in the X and Y directions. That is, the partition walls 110 are provided in regions overlapping with the auxiliary electrodes 115.

[0093] Furthermore, when an opening is formed in a partition made of an organic material, the upper end of the partition 110 may be rounded as shown in FIG. 1B1. "Rounded" may also be referred to as "having a curvature." Note that in the partition 110, at least the upper end of the second insulator 121 may have a curvature. When an opening is formed, the lower end of the partition 110 may also have a curvature. Note that in the partition 110, at least the lower end of the first insulator 120 may have a curvature.

[0094] As shown in FIGS. 1B1 and 1C , in the cross-sectional views of the pixel region 10, the end of the partition 110 may have a tapered shape. For example, the partition 110 may have a structure in which the diameter of the bottom surface is longer than the diameter of the top surface, resulting in a forward tapered shape with the end tapered. Furthermore, the partition 110 may have a structure in which the diameter of the bottom surface is shorter than the diameter of the top surface, resulting in a reverse tapered shape with the end tapered. Both tapered shapes have in common the inclined end of the partition 110. The inclined end allows the inkjet solution to be dropped into the target pixel, thereby suppressing color mixing. Note that, in the partition 110, when the thickness of the second insulator 121 is greater than the thickness of the first insulator 120, it is sufficient that at least the end of the second insulator 121 has an inclination. The taper angle of the end of the partition wall 110 may be more obtuse than the taper angle of the end of the lower electrode 116, and is preferably 15 degrees or more and 70 degrees or less, and more preferably 20 degrees or more and 60 degrees or less.

[0095] 1B1 and 1C, layer 150 is formed on lower electrode 116. Layer 150 is located between lower electrode 116 and light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B, which will be described later, and has the function of being able to inject holes from lower electrode 116 to light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B. For example, layer 150 can be configured as a structure having a hole injection layer, a structure having a hole transport layer, or a structure in which a hole injection layer and a hole transport layer are stacked in this order from lower electrode 116. Layers 150 may be distinguished by ordinal numbers, such as a first layer and a second layer.

[0096] The layer 150 is preferably formed by a wet method, for example. Wet methods include spin coating, inkjet printing, casting, printing, dispensing, and spraying. By forming at least the layer 150 by a wet method, productivity can be improved. A structure in which at least the layer 150 is formed by a wet method is suitable for a flexible display device. FIG. 1B2 explains the film thickness of the layer 150 formed by a wet method using an enlarged view of the area circled and arrowed in FIG. 1B1, i.e., the end of the partition wall 110. FIG. 1B2 shows a first insulator 120 and a second insulator 121.

[0097] First, the end of the first insulator 120 is defined as the center (C). The distance from the center (C) to the end of the layer 150 (the end located on the side overlapping the slope of the partition wall 110) is defined as L1. The same distance L1 is assigned to the side of the center (C) facing the end of the layer 150, indicating the range of distance L1 from the center (C). The range of distance L1 may be referred to as the region near the partition wall. The film thickness of the layer 150 is thicker in the region near the partition wall than in the central part of the light-emitting area. In other words, the region near the partition wall may become thicker. This thickened portion may be referred to as a liquid puddle. The film thickness of the layer 150 is often thickest in the region overlapping the center (C). The layer 150 that is thickened in the region near the partition wall in this way can be said to have been produced by a wet method.

[0098] The layer 150 may be formed over the entire pixel region 10 without being divided for each pixel. That is, the layer 150 may be formed over a plurality of lower electrodes and may be shared by each pixel. The layer 150 may be formed by a wet method or a vapor deposition method. The layer 150 that can be shared by pixels is preferably formed by a spin coating method or a vapor deposition method.

[0099] 1B1 and 1C, the layer 150 may be divided into pixels by the partition walls 110. When the layer 150 is formed using a spin coating method, a structure in which the layer 150 is not located on the upper surface of the partition walls 110 can be obtained by performing a liquid-repellent treatment on the upper surface of the partition walls 110. When the layer 150 is formed using a vapor deposition method, a structure in which the layer 150 is not located on the upper surface of the partition walls 110 can be obtained by performing the vapor deposition using a metal mask.

[0100] <Light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B> Light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B are formed on layer 150 by applying different colors. This applied structure corresponds to the SBS structure. The light-emitting colors of light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B correspond to red, green, and blue, respectively, enabling full-color display.

[0101] The light-emitting layers 153R, 153G, and 153B are preferably formed by a wet method similar to that used for the layer 150. Wet methods include spin coating, inkjet printing, casting, printing, dispensing, and spraying. By forming at least the light-emitting layers by a wet method, productivity can be improved. A structure in which at least the light-emitting layers are formed by a wet method is suitable for a flexible display device.

[0102] 1B2, the light-emitting layers 153R, 153G, and 153B are also thickened in the region near the partition wall 110. That is, the thicknesses of the light-emitting layers 153R, 153G, and 153B are larger in the region near the partition wall than in the central region of the light-emitting area of ​​the partition wall.

[0103] The light-emitting layers 153R, 153G, and 153B, which are thickened in the regions near the partition walls, can be said to have been produced by a wet method.

[0104] <Inkjet method> An inkjet device that can be used in the inkjet method is shown in Figures 4A and 4B. Figure 4A shows the process of forming light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B, and Figure 4B shows the process of forming light-emitting layer 153G. Note that layer 150 may be formed using the inkjet device shown in Figures 4A and 4B, and the layer 150 and light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B can also be formed using the same inkjet device. Forming the layers by a wet method can improve productivity.

[0105] Figures 4A and 4B show inkjet nozzles 119R, 119G, and 119B of the inkjet device. The opening diameters of the inkjet nozzles 119R, 119G, and 119B (also referred to as inkjet nozzle diameters) are several microns to several tens of microns. The part containing the inkjet nozzles is sometimes referred to as the head. To dispense the solution, the head is equipped with a solution spray control unit and also includes a piezoelectric element (piezo element). The pressure element changes the volume of the ink tank connected to the inkjet nozzle to dispense the solution from the head. The volume of one droplet is often several pl to several tens of pl, depending on the inkjet nozzle diameter. Although it depends on the material, 1 pl of solution can be considered to be the amount that forms a cube with sides of approximately 10 µm.

[0106] The solution may be intermittently dropped from the inkjet nozzles 119R, 119G, and 119B, or may be dropped continuously in a line from the inkjet nozzles 119R, 119G, and 119B.

[0107] By using the inkjet method, as shown in Fig. 4A, light-emitting layers 153R, 153G, and 153B corresponding to the respective emitted colors can be simultaneously formed in the openings of partition wall 110. Fig. 4B shows a cross-sectional view of light-emitting layer 153G, showing the state just before inkjet nozzle 119R, which can move in the direction of the arrow, passes over partition wall 110. For other configurations in Figs. 4A and 4B, Fig. 1 and the like can be referred to.

[0108] In the layer formed by the inkjet method, puddles are observed near the partition wall 110. The puddles can be seen from the explanation using FIG. 1B2 above, and correspond to thickened portions of the light-emitting layer 153R, the light-emitting layer 153G, the light-emitting layer 153B, or the layer 150 near the partition wall 110.

[0109] The liquid pools are formed during the drying process carried out in a normal or reduced pressure atmosphere to remove the solvent. 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. When such liquid pools are observed, it is clear that the layer was formed by a wet method such as the inkjet method.

[0110] When formed by a wet method such as an inkjet method, at least the light-emitting layer can be applied without using a metal mask, and therefore a light-emitting device having such a light-emitting layer can be said to have an MML structure.

[0111] <Vapor deposition method> The light-emitting layer 163R, the light-emitting layer 163G, and the light-emitting layer 163B may be formed by a vapor deposition method. FIGS. 5A and 5B show the formation of the light-emitting layer 163R, the light-emitting layer 163G, and the light-emitting layer 163B using a vapor deposition method. The layer 160 located below the light-emitting layer 163R, the light-emitting layer 163G, and the light-emitting layer 163B can also be formed using a vapor deposition method, but in FIG. 5A, the layer 160 is formed by a wet method. Because the layer 160 is common to each pixel, it is preferable to form it by a spin coating method. For other configurations in FIGS. 5A and 5B, reference can be made to FIG. 1, etc.

[0112] 5A and 5B show a metal mask 161. In these figures, a metal mask 161 having openings that overlap with pixels of the same color is used to form the light-emitting layers 163G and the like. The metal mask 161 can be shifted, for example, two or more times, to form the remaining light-emitting layers. Specifically, a fine metal mask can be used as the metal mask 161.

[0113] When formed by vapor deposition, at least the light-emitting layer is produced using a metal mask, specifically a fine metal mask, and therefore a light-emitting device having such a light-emitting layer can be said to have an MM structure.

[0114] In the layer formed by the vapor deposition method, no liquid pools are observed near the partition walls 110 .

[0115] The light-emitting layer is preferably formed by a wet method such as an ink-jet method, because this has high productivity, but may also be formed by a vapor deposition method.

[0116] 1B1 and 1C , layer 155 is formed. Layer 155 is located between upper electrode 159 and light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B, and has the function of being able to inject electrons from upper electrode 159 to light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B. For example, layer 155 can have a structure including an electron injection layer, a structure including an electron transport layer, or a structure in which an electron injection layer and an electron transport layer are stacked in this order from upper electrode 159.

[0117] As shown in FIGS. 1B1 and 1C, the layer 155 may be formed over the entire pixel region 10 without being divided for each pixel. The layer 150 may be formed across multiple light-emitting layers and may be shared by each pixel. The layer 155 may be formed by a wet method or a vapor deposition method. Wet methods include spin coating, inkjet printing, casting, printing, dispensing, and spraying. The layer 155 that can be shared by pixels is preferably formed by a spin coating method or a vapor deposition method.

[0118] <Upper electrode 159> The upper electrode 159 is formed on the layer 155. The upper electrode 159 corresponds to the upper electrode of a pair of electrodes that the light-emitting device has, and functions as, for example, a cathode. The upper electrode 159 may also be referred to as a counter electrode.

[0119] As shown in FIGS. 1B1 and 1C , the upper electrode 159 may be formed over the entire pixel region 10 without being divided for each pixel. The upper electrode 159 may be formed across multiple light-emitting layers and may be shared by each pixel. The upper electrode 159 may be formed by a wet method or a vapor deposition method. Wet methods include spin coating, inkjet printing, casting, printing, dispensing, and spraying. The upper electrode 159 that can be shared by pixels is preferably formed by a spin coating method or a vapor deposition method.

[0120] Since the upper electrode 159 functions as a cathode, it is preferable to use a material with a small work function (such as Al, Mg, Li, Ca, alloys of these (an alloy containing Mg and Ag is referred to as MgAg, an alloy containing Mg and In is referred to as MgIn, and an alloy containing Al and Li is referred to as AlLi), or compounds of these). When light generated in the light-emitting layer is transmitted through the upper electrode 159, a thin metal thin film can be used as the upper electrode 159. Alternatively, a transparent conductive film (such as ITO, indium oxide containing 2 wt % to 20 wt % zinc oxide, indium tin oxide containing silicon, or zinc oxide (ZnO)) can be used as the upper electrode 159. Furthermore, a laminate of a metal thin film and a transparent conductive film can be used as the upper electrode 159.

[0121] Since the upper electrode 159 is electrically connected to the auxiliary electrode 115, as shown in FIG. 1C , the contact hole 18 is formed before the formation of the upper electrode 159. The contact hole 18 can be formed, for example, by photolithography. Photolithography includes a method of forming a resist mask on a thin film to be processed, processing the thin film by etching or the like, and then removing the resist mask, and a method of forming a photosensitive thin film, and then processing the thin film into a desired shape by exposure and development. For example, after forming the layer 155, a mask for forming the contact hole 18 is prepared, and a resist mask can be used as the mask.

[0122] 1B1 and 1C, a structure can be used in which the light-emitting layer is not located on the upper surface of the partition wall 110. With this structure, when forming the contact hole 18, the light-emitting layer is protected on the upper surface by the layer 155 and on the side by the partition wall 110, so the light-emitting layer is not exposed to the etching agent. In this case, the contact hole 18 can be formed using only a resist mask.

[0123] In order to reduce damage to an organic material layer or organic compound layer, such as a light-emitting layer, during processing, a sacrificial layer (sometimes referred to as a mask layer) may be formed between the resist mask and the layer 155. In this specification and the like, the sacrificial layer has a function of protecting a functional layer, such as a light-emitting layer, during the manufacturing process. Specifically, when processing a light-emitting device, the sacrificial layer is formed at a position where the light-emitting layer, etc., will not be damaged by processing. During the manufacturing process of the light-emitting device, the sacrificial layer may be completely removed, or a portion may be left.

[0124] By providing a sacrificial layer in this way, the reliability of the light-emitting device can be improved. To reiterate, a sacrificial layer is a layer provided to protect a material layer (a material layer is the target of processing and is sometimes referred to as a processed layer) formed below it from process damage when the processed layer is processed by etching or the like. For this reason, the sacrificial layer may be formed thicker than the processed layer.

[0125] The sacrificial layer may be, for example, a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic insulating film. The sacrificial layer may be formed by various film formation methods such as sputtering, vapor deposition, CVD, or ALD. A formation method that causes less damage to the organic material layer or organic compound layer is preferred, and the sacrificial layer is preferably formed by ALD or vacuum vapor deposition.

[0126] The sacrificial layer may be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing such a metal material. In particular, it is preferable to use a low-melting-point material such as aluminum or silver.

[0127] The sacrificial layer can be made of a metal oxide such as indium gallium zinc oxide (In-Ga-Zn oxide, also referred to as IGZO). Other examples include indium oxide, indium zinc oxide (In-Zn oxide), indium tin oxide (In-Sn oxide), indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), and indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide). Alternatively, silicon-containing indium tin oxide can be used.

[0128] The present invention can also be applied to a case where, instead of the gallium, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) is used. In particular, it is preferable that M is one or more elements selected from gallium, aluminum, and yttrium.

[0129] The sacrificial layer can be made of an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide.

[0130] When the sacrificial layer has a laminated structure, a layer made of the above-mentioned material can be used as a first sacrificial layer, and a second sacrificial layer can be laminated thereon.

[0131] When the sacrificial layer is provided, the sacrificial layer may also be processed, and in this case, the sacrificial layer may be made of a material having a high etching selectivity with respect to the organic material layer or the organic compound layer, or the partition wall 110.

[0132] When a sacrificial layer is used, it is preferable to use a material that can be removed by wet etching. Although the organic material layer or organic compound layer may be damaged during removal, removing the sacrificial layer by wet etching can reduce the damage compared to removing the sacrificial layer by dry etching.

[0133] The upper electrode 159 and the auxiliary electrode 115 can be electrically connected through the contact hole 18 formed in this manner. In a cross-sectional view of the contact hole 18, the opening of the first insulator 120 is smaller than the opening of the second insulator 121, and an end of the first insulator 120 is exposed through the opening of the second insulator 121. Furthermore, in a top view of the contact hole 18, an end of the first insulator 120 is exposed through the opening of the second insulator 121. Because the formation of the opening of the second insulator 121 begins before the formation of the opening of the first insulator 120, the opening of the second insulator 121 widens. Furthermore, because the opening of the layer 155 is formed first, the opening widens, and the end of the layer 155 that defines the opening may recede to a position overlapping the upper surface of the partition wall 110. That is, the diameter of the opening of each layer gradually decreases toward the auxiliary electrode 115 below.

[0134] In the contact hole 18, a structure in which the diameter of the opening of each layer becomes smaller in stages toward the auxiliary electrode 115 is preferable because the upper electrode 159 is less likely to be cut (sometimes referred to as step disconnection) at the contact hole 18. Furthermore, since the upper electrode 159 is electrically connected to the auxiliary electrode 115, it is preferable to etch a part of the surface of the auxiliary electrode 115 (this is referred to as over-etching). When a part of the surface is etched, a recess is formed in the surface of the auxiliary electrode 115, and using a recess is preferable because it increases the contact area between the auxiliary electrode 115 and the upper electrode 159.

[0135] Although FIG. 1C shows a structure in which layer 155 is not located within contact hole 18, layer 155 may be located within contact hole 18. For example, as shown in FIG. 3, even if layer 155 is located between auxiliary electrode 115 and upper electrode 159 in contact hole 18, it is sufficient that auxiliary electrode 115 and upper electrode 159 are electrically connected. In this structure, contact hole 18 is formed before layer 155 is formed. It is preferable to dispose a sacrificial layer when forming contact hole 18. For other configurations in FIG. 3, reference can be made to FIG. 1, etc.

[0136] The contact holes 18 can be provided at any desired locations. For example, as shown in FIG. 1A, one contact hole 18 may be formed for every six pixels. Since the upper electrode 159 is shared in the pixel region 10, a voltage drop is likely to occur, but it is sufficient if the resistance of the upper electrode 159 can be reduced by the auxiliary electrode 115. Therefore, it is sufficient to form one contact hole 18 for multiple pixels, and there is no need to form one contact hole 18 for each pixel.

[0137] <Height of Partition 110> In the pixel region 10, the lattice-shaped partition 110 has a first region 110x along the X direction and a second region 110y along the Y direction. In one embodiment of the present invention, the heights of the partitions 110 may be different, for example, the heights of the first region 110x and the second region 110y may be different. The perspective view of the pixel region 10 shown in Figure 6 shows a case where the second region 110y is higher than the first region 110x, that is, when comparing the positions of the top surfaces of the respective regions, the second region 110y is higher than the first region 110x.

[0138] The partition 110 preferably has a layered structure in which a second insulator 121 containing an organic material is located on a first insulator 120 containing an inorganic material, and in order to vary the height of the partition 110, the first insulator 120 may correspond to the first region 110x, and the layered structure of the first insulator 120 and the second insulator 121 may correspond to the second region 110y. For example, after forming the first insulator 120 in a lattice shape, the second insulator 121 may be formed only in the portion corresponding to the second region 110y.

[0139] Even if the partition wall is formed only from an organic material, a high partition wall can be obtained in the second region 110y. First, a partition wall having a thickness Hx is formed from an organic material in the X direction, including the first region 110x. Then, a partition wall having a thickness Hy (Hy > Hx, and Hy is preferably 1.2 to 2.5 times the thickness of Hx) is formed from an organic material in the Y direction, including the second region 110y. When formed in this manner, the partition wall 110 has its highest height at the intersection of the X and Y directions, as shown in the perspective view of FIG. 6 .

[0140] The inkjet nozzles 119R, 119G, and 119B shown in FIG. 4 and other figures can be moved along the second region 110y shown in FIG. 6. Furthermore, the second region 110y is a high partition wall, which can suppress color mixing. Suppressing color mixing is particularly advantageous when light-emitting layers of different colors are simultaneously formed for the pixels 11R, 11G, and 11B.

[0141] The first region 110x is located at the boundary between pixels of the same color. The first region 110x is a partition wall that is lower than the second region 110y. Therefore, in order to suppress color mixing, it is possible to form the light-emitting layer by the inkjet method even without the first region 110x. However, the first region 110x is preferable because it can suppress liquid unevenness between pixels of the same color.

[0142] 7A and 7B are cross-sectional views taken along the first region 110x. In these figures, a single-layer partition wall is used in the first region 110x. Specifically, a first insulator 120 is used as the single-layer partition wall.

[0143] When forming the light-emitting layer 153G by the inkjet method, the inkjet nozzle 119G is moved along the second region 110y. As a result, the light-emitting layer 153G is formed on the first insulator 120. The solution dropped from the inkjet nozzle 119G evaporates quickly in the region where the amount is small. As shown in FIG. 7A , the amount of solution on the first insulator 120 is less than in other regions, so evaporation of the solution on the first insulator 120 completes quickly. When evaporation of the solution on the first insulator 120 completes quickly, the movement of the solution between pixels that emit the same light, such as the first green pixel 11G1 and the second green pixel 11G2, is reduced, thereby suppressing liquid unevenness.

[0144] 7B shows the case where the light-emitting layer 163G is formed by evaporation. Since the first insulator 120 is covered with the metal mask 161, the light-emitting layer 163G is not formed on the first insulator 120.

[0145] In such a low partition wall, a contact hole 18 may be formed. When forming the contact hole 18, a sacrificial layer may be formed on the light-emitting layer.

[0146] The perspective view of FIG. 6 is an example of the height of the partition wall 110, and the first region 110x may be higher than the second region 110y.

[0147] In this way, the pixel region 10 has a light-emitting device in each pixel, and the upper electrode of the light-emitting device can be electrically connected to the auxiliary electrode. The auxiliary electrode can reduce the voltage drop caused by the upper electrode. Since the auxiliary electrode is located in an area overlapping with the partition wall, it does not reduce the aperture ratio. Such an auxiliary electrode is preferably applied to a high-resolution display device with a high aperture ratio.

[0148] This embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification etc. For example, part of the structure shown in this embodiment mode may be implemented in appropriate combination with other embodiment modes described in this specification etc.

[0149] In this embodiment, a pixel region having an auxiliary electrode in a display device according to one embodiment of the present invention will be described. Specifically, the display device will be described in which the arrangement of the auxiliary electrode 115, the lower electrode 116, and the like is different from that in the above-described embodiment 1. The description of the components and the like having the same numbers as those in the above-described embodiment 1 may be omitted in this embodiment.

[0150] 8B and 8C, the auxiliary electrode 115 is formed on the insulating layer 106, an insulating layer 107 is newly formed on the auxiliary electrode 115, and a lower electrode 116 is formed on the insulating layer 107. This arrangement differs from the above embodiment.

[0151] FIG. 8A shows a top view (also referred to as a plan view) including the auxiliary electrode 115. The auxiliary electrode 115 may be arranged in a lattice pattern, as in FIG. 1A, but may also extend to the region where it overlaps with the lower electrode 116. Therefore, the auxiliary electrode 115 of this embodiment can have a narrower lattice spacing than that of FIG. 1A. The auxiliary electrode 115 may have a region that crosses the center of the pixel 11R along the X direction. This embodiment can obtain an auxiliary electrode 115 with a larger area than the above-described embodiments. Furthermore, since it is not necessary to share the conductive material with the lower electrode 116, material selection is high, and the voltage drop of the upper electrode 159 can be more effectively reduced than the configuration of the auxiliary electrode 115 of this embodiment.

[0152] As described above, by forming the auxiliary electrode 115 on a surface different from that of the lower electrode 116, flexibility is given to the conductive material used for the auxiliary electrode 115. For example, the auxiliary electrode 115 can be made of a material having a lower resistivity than the lower electrode 116.

[0153] Furthermore, as described above, the lower electrode 116 and the surface on which it is formed can be made different, which provides a degree of freedom in the arrangement of the auxiliary electrode 115. In the above embodiment in which the lower electrode 116 and the surface on which it is formed are made the same, the auxiliary electrode 115 could not be in contact with the lower electrode 116, but in this embodiment, since the insulating layer 107 is interposed, the auxiliary electrode 115 can overlap the lower electrode 116 when viewed from above, and it is possible to obtain the auxiliary electrode 115 with a large area.

[0154] As shown in FIGS. 8B and 8C , the lower electrode 116 is electrically connected to the source and drain 103 via contact holes 15R, 15G, and 15B. A conductive layer 114 is preferably interposed between the lower electrode 116 and the source and drain 103. The conductive layer 114 is formed using the same material as the auxiliary electrode 115. By interposing the conductive layer 114, openings can be formed in the insulating layer 106 and the insulating layer 107. The openings in the insulating layer 106 are preferably formed so as not to overlap with the openings in the insulating layer 107 in a cross-sectional view. Applying the openings thus formed to the contact holes 15R, 15G, and 15B is preferable because it increases yield.

[0155] 8C , the upper electrode 159 is electrically connected to the auxiliary electrode 115 through the contact hole 18. A conductive layer 117 is preferably interposed between the upper electrode 159 and the auxiliary electrode 115. The conductive layer 117 is formed using the same material as the lower electrode 116. By interposing the conductive layer 117, openings can be formed in the insulating layer 107 and the partition wall 110, respectively. Forming openings in the insulating layer 107 and the partition wall 110, respectively, is preferable to forming openings in both the insulating layer 107 and the partition wall 110 at the same time, as this increases the yield.

[0156] 8A to 8C, the structures other than those described above are the same as those of the above embodiment.

[0157] 9 shows a case where layer 155 is located between upper electrode 159 and auxiliary electrode 115 in contact hole 18 as in FIG. 3. Except for the fact that layer 155 is interposed between upper electrode 159 and auxiliary electrode 115, this embodiment is the same as the first embodiment.

[0158] 10A and 10B show the formation of light-emitting layers 153R, 153G, and 153B using the inkjet method as in FIGS. 4A and 4B. In FIG. 10A, a conductive layer 114 is interposed between the lower electrode 116 and the source and drain 103. In FIG. 10B, a conductive layer 117 electrically connected to an auxiliary electrode 115 is provided. FIG. 10B is a cross-sectional view before the upper electrode 159 is formed, and the auxiliary electrode 115 shown in the figure is electrically connected to the upper electrode 159 via the conductive layer 117. The other configurations are the same as those in the first embodiment.

[0159] 11A and 11B show the formation of light-emitting layers 163R, 163G, and 163B using a vapor deposition method as in FIGS. 5A and 5B. In FIG. 11A, a conductive layer 114 is interposed between the lower electrode 116 and the source and drain 103. In FIG. 11B, a conductive layer 117 electrically connected to an auxiliary electrode 115 is provided. FIG. 11B is a cross-sectional view before the upper electrode 159 is formed, and the auxiliary electrode 115 shown in the figure is electrically connected to the upper electrode 159 via the conductive layer 117. The other configurations are the same as those in the first embodiment.

[0160] In this embodiment as well, the heights of the partition walls 110 may be made different as shown in the perspective view of FIG.

[0161] 12A and 12B show cross-sectional views along a first region 110x as in Figures 7A and 7B. For example, the first region 110x has a first insulator 120.

[0162] 12A shows how, when forming light-emitting layer 153G by inkjet printing, inkjet nozzle 119G is moved along second region 110y. As a result, light-emitting layer 153G is formed on first insulator 120. Also shown in FIG. 12A is a cross-sectional view before upper electrode 159 is formed, and auxiliary electrode 115 shown in the figure is electrically connected to upper electrode 159 via conductive layer 117. Other configurations are the same as those in the first embodiment.

[0163] 12B shows a case where a light-emitting layer 163G is formed by vapor deposition. Because the first insulator 120 is covered with a metal mask 161, the light-emitting layer 163G is not formed on the first insulator 120. Also, in FIG. 12B, a conductive layer 117 electrically connected to the auxiliary electrode 115 is provided. FIG. 12B is a cross-sectional view before the upper electrode 159 is formed, and the auxiliary electrode 115 shown in the figure is electrically connected to the upper electrode 159 via the conductive layer 117. The other configurations are the same as those in the first embodiment.

[0164] In this way, the pixel region 10 has a light-emitting device in each pixel, and the upper electrode of the light-emitting device can be electrically connected to the auxiliary electrode. The auxiliary electrode can reduce the voltage drop caused by the upper electrode. Since the auxiliary electrode is located below the partition wall, it is preferable to apply it to a high-resolution display device with a high aperture ratio.

[0165] This embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification etc. For example, part of the structure shown in this embodiment mode may be implemented in appropriate combination with other embodiment modes described in this specification etc.

[0166] Embodiment 3 In this embodiment, a pixel region having an auxiliary electrode in a display device according to one embodiment of the present invention will be described.

[0167] As shown in Figure 13A, the pixel region 10 of the display device has a plurality of pixels. A pixel is considered to be the smallest unit that has at least a light-emitting device and can emit one emitted color. Such a pixel may be referred to as a sub-pixel.

[0168] The configuration of the light-emitting device is the same as that of the above-described embodiment 1. In the region indicated by the arrow in Fig. 13A, pixel region 10 has pixel 11R capable of exhibiting red, pixel 11G capable of exhibiting green, and pixel 11B capable of exhibiting blue. Ordinal numbers may be assigned to distinguish the pixels, and for example, they may be referred to as a first red pixel, a second red pixel, and so on.

[0169] In describing the pixel region 10, the X direction and the Y direction intersecting the X direction may be used, as shown in FIG. 13A . For example, in the pixel region 10, the pixel 11R, the pixel 11G, and the pixel 11B are arranged in order in the X direction, and multiple pixels 11R are arranged in the Y direction. Similarly, multiple pixels 11B and 11G are arranged in the Y direction. In addition, in the pixel region 10, the pixel 11G is located in a region adjacent to the pixel 11R in the X direction, and another pixel 11R is located in a region adjacent to the pixel 11R in the Y direction. Ordinal numbers may be used to distinguish between the same elements. For example, the other pixel 11R may be referred to as the second pixel 11R.

[0170] Pixel 11R has at least a contact hole 15R. Contact hole 15R is an opening provided in an insulating layer located between a light-emitting device and a transistor that drives the light-emitting device to ensure electrical connection between the light-emitting device and the transistor. Similarly, pixel 11G has at least a contact hole 15G, and pixel 11B has at least a contact hole 15B.

[0171] As shown in FIG. 13A, the pixel region 10 has an auxiliary electrode 115 .

[0172] 13A shows a case where the auxiliary electrodes 115 are arranged between the pixels in the pixel region 10. The auxiliary electrodes 115 have regions extending in the X and Y directions, and appear in a grid pattern when viewed from above. However, the arrangement of the auxiliary electrodes is not limited to the grid pattern as long as they are arranged to reduce the resistance of the main electrodes.

[0173] The pixel region 10 has a contact hole 18. The contact hole 18 is an opening provided in an insulating layer located between the auxiliary electrode 115 and the upper electrode 216 in order to ensure electrical connection between the auxiliary electrode 115 and the upper electrode 216 of the light-emitting device. The upper electrode 216 will be described later. It is preferable that the contact hole 18 has a larger diameter than the contact holes 15R and the like that each pixel has.

[0174] Fig. 13B shows a cross-sectional view taken along line A1-A2 and passing through contact holes 15R, 15G, and 15B. Fig. 13C shows a cross-sectional view taken along line B1-B2 and passing through contact hole 18. The pixel region 10 will be described with reference to Figs. 13B and 13C.

[0175] 13B and 13C show an example in which a transistor 101 is provided over a substrate 100. The transistor 101 is an element for driving a light-emitting device (referred to as a driving element). A display device having such a driving element in each pixel is referred to as an active matrix display device.

[0176] 13B illustrates a top-gate transistor in which the gate 102 is located above the semiconductor layer as the transistor 101. Of course, in the present invention, a bottom-gate transistor in which the gate is located below the semiconductor layer, or a dual-gate transistor in which the gate is located above and below the semiconductor layer may also be applied.

[0177] A gate insulating layer is located between the gate 102 and the semiconductor layer. The semiconductor layer can be formed using silicon or an oxide semiconductor, and may be crystalline or amorphous. When the semiconductor layer is formed using silicon, the regions in contact with the source and drain 103 are called impurity regions, and elements other than silicon, such as phosphorus or boron (referred to as impurity elements), are added to reduce resistance (the impurity regions are also referred to as low-resistance regions).

[0178] The gate 102 is covered with at least an insulating layer 105. The source and drain 103 can each have a region in contact with the semiconductor layer through an opening provided in the gate insulating layer and an opening provided in the insulating layer 105. In Fig. 13C, it can be seen that one of the source and drain 103 is in contact with the semiconductor layer.

[0179] The gate insulating layer and the insulating layer 105 preferably contain an inorganic material, which can prevent impurity elements from entering the semiconductor layer.

[0180] The inorganic material may be 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 impurity elements such as lanthanum (La), nitrogen, and zirconium (Zr) may be added to the above materials.

[0181] An insulating layer 106 is provided on the insulating layer 105. The upper surface of the insulating layer 106 preferably has flatness because it corresponds to a surface on which a lower electrode of a light-emitting device to be formed later will be formed. For example, the insulating layer 106 can be provided with the above flatness by forming it using an organic material.

[0182] The organic material may be an organic resin such as polyimide resin, polyamide resin, acrylic resin, siloxane resin, silicone resin, epoxy resin, or phenol resin. Note that impurity elements such as lanthanum, nitrogen, or zirconium may be added to the above materials.

[0183] [Application Example of Transistor] As a cross-sectional structure example of a transistor that can be applied to the transistor 101, the structure described in [Application Example of Transistor] in Embodiment 1 can be used.

[0184] <Bottom Electrode 259> A bottom electrode 259 is formed on the insulating layer 106. FIG. 13A shows a top view of the bottom electrode 259. The bottom electrode 259 corresponds to the lower electrode of a pair of electrodes of the light-emitting device, and functions as, for example, a cathode. The bottom electrode 259 is located on the transistor 101 side, is electrically connected to the transistor 101, and can supply a signal from the transistor 101 to the light-emitting device. Because the signal differs for each pixel, the bottom electrode 259 is processed so that it is independent for each pixel. This processing is sometimes referred to as patterning. The pixel 11R, pixel 11G, and pixel 11B each have a bottom electrode 259, and such a bottom electrode 259 is sometimes referred to as a pixel electrode.

[0185] The shape of the upper surface of the lower electrode 259 is not limited, but in FIG. 13A, the lower electrode 259 has a rectangular shape with short sides along the X direction and long sides along the Y direction.

[0186] The cross-sectional shape of the lower electrode 259 is not limited, but the end portion may preferably have a tapered shape.

[0187] Since the lower electrode 259 is electrically connected to the transistor 101, the insulating layer 106 between them has openings that function as contact holes. For example, in FIG. 13B , openings formed in the insulating layer 106 are contact holes 15R, 15G, and 15B, respectively. Each contact hole has a region where one of the source and drain 103 contacts the lower electrode 259. However, as long as electrical connection is achieved via the contact hole, for example, another conductive layer may be interposed between one of the source and drain 103 and the lower electrode 259. In other words, a structure in which one of the source and drain 103 and the lower electrode 259 do not contact each other is also possible.

[0188] Because the lower electrode 259 functions as a cathode, it is preferable to use a material with a low work function. Therefore, the lower electrode 259 can be formed using a single layer of an ITO film (an oxide film containing indium and tin), an indium tin oxide film containing silicon, an indium oxide film containing 2 wt % to 20 wt % zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, a Cu film, an Al film, or the like. It can also be formed using a laminated structure of a titanium nitride film and a film primarily composed of aluminum, or a laminated structure of a titanium nitride film, a film primarily composed of aluminum, and another titanium nitride film. The aluminum-based film may contain nickel, tungsten, or a rare earth element (e.g., lanthanum) in addition to aluminum. When using such a laminated structure, it is preferable to use a low-resistance material for one layer and a material capable of forming a good ohmic contact with one of the source and drain electrodes 103 for the other layer. The overall thickness of the lower electrode 259 is preferably 100 nm to 250 nm.

[0189] In the case of a display device in which light from a light-emitting device is extracted from the side of the lower electrode 259, the lower electrode 259 needs to have light-transmitting properties. To have light-transmitting properties, a light-transmitting material is selected from the above-mentioned materials, or when a light-non-transmitting material is selected, a structure such as a thin film is used.

[0190] <Auxiliary electrode 115> The auxiliary electrode 115 is formed using the same material as the lower electrode 259. FIG. 13A shows a top view of the lower electrode 259 and the auxiliary electrode 115. FIGS. 13B and 13C show cross-sectional views of the lower electrode 259 and the auxiliary electrode 115 on the insulating layer 106. The auxiliary electrode 115 is processed so as not to have the same potential as the lower electrode 259, that is, it is necessary to make them independent of each other. FIG. 13A shows an example in which the auxiliary electrode 115 is arranged independent of each other, but the auxiliary electrode 115 is arranged in a shape having regions extending in the X and Y directions, i.e., in a lattice pattern, so as not to contact the lower electrode 259. The distance between the lower electrode 259 and the auxiliary electrode 115 in the region along the Y direction is preferably greater than the distance between the lower electrode 259 and the auxiliary electrode in the region along the X direction.

[0191] The auxiliary electrode 115 enables electrical connection with an upper electrode 216 of a light-emitting device to be formed later. The auxiliary electrode 115 can reduce the resistance of the upper electrode 216 and suppress voltage drop.

[0192] <Partition Wall 110> In FIGS. 13B and 13C, the partition wall 110 is formed on the lower electrode 259 and the auxiliary electrode 115. In FIGS.

[0193] As shown in Fig. 13B, the partition 110 covers the end of the lower electrode 259 and has an opening so that the center of the lower electrode 259 is exposed. In Fig. 13B, it can be seen that the partition 110 covers the entire auxiliary electrode 115, but as shown in Fig. 13C, the auxiliary electrode 115 is electrically connected to the upper electrode, so an opening is formed in the partition 110, which becomes a contact hole 18. The auxiliary electrode 115 in the region overlapping with the contact hole 18 extends along the X direction. It is preferable that the width of the auxiliary electrode in the overlapping region is wider than the width of the auxiliary electrode in the region not overlapping with the contact hole 18.

[0194] In one embodiment of the present invention, similarly to the first embodiment, the partition wall 110 preferably includes a first insulator 120 and a second insulator 121 .

[0195] The partition walls 110 are configured to separate the pixels when viewed from above the pixel region 10, that is, have a lattice shape having regions extending in the X and Y directions. That is, the partition walls 110 are provided in regions overlapping with the auxiliary electrodes 115.

[0196] Furthermore, as shown in FIGS. 13B and 13C , the partition wall 110 formed with the opening may have a rounded upper end portion, where the opening is formed. To be rounded may also be referred to as having a curvature. Note that in the partition wall 110, at least the upper end portion of the second insulator 121 may have a curvature. When an opening is formed, the lower end portion of the partition wall 110 may also have a curvature. Note that in the partition wall 110, at least the lower end portion of the first insulator 120 may have a curvature.

[0197] As shown in FIGS. 13B and 13C , in the cross-sectional views of the pixel region 10, the end of the partition 110 may have a tapered shape. For example, the partition 110 may have a structure in which the diameter of the bottom surface is longer than the diameter of the top surface, resulting in a forward tapered shape with the end tapered. Furthermore, the partition 110 may have a structure in which the diameter of the bottom surface is shorter than the diameter of the top surface, resulting in a reverse tapered shape with the end tapered. Both tapered shapes have in common the inclined end of the partition 110. The inclined end allows the inkjet solution to be dropped into the target pixel, thereby suppressing color mixing. In the partition 110, the second insulator 121 has a larger thickness than the first insulator 120, so it is sufficient that at least the end of the second insulator 121 has an inclination. The taper angle of the end of the partition wall 110 may be more obtuse than the taper angle of the end of the lower electrode 259, and is preferably 15 degrees to 70 degrees, more preferably 20 degrees to 60 degrees.

[0198] 13B and 13C , layer 155 is formed on lower electrode 259. Layer 155 is located between lower electrode 259 and light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B, and has the function of being able to inject electrons from lower electrode 259 to light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B. For example, layer 155 can have a structure having an electron injection layer, a structure having an electron transport layer, or a stacked structure of an electron injection layer and an electron transport layer.

[0199] The layer 155 may be formed over the entire pixel region 10 without being divided for each pixel. That is, the layer 155 may be formed over a plurality of lower electrodes and may be common to each pixel. The layer 155 may be formed by vapor deposition.

[0200] 13B and 13C, the layer 155 may be divided into pixels by the partition walls 110. When the layer 155 is formed by evaporation, if the evaporation is performed using a metal mask, a structure in which the layer 155 is not located on the upper surface of the partition walls 110 can be obtained.

[0201] <Light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B> Light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B are formed on layer 155 by applying different colors. This applied structure corresponds to the SBS structure. The light-emitting colors of light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B correspond to red, green, and blue, respectively, enabling full-color display. The other configurations are the same as those in the first embodiment.

[0202] 15A and 15B show an inkjet device that can be used for the inkjet method. Fig. 15A shows the formation of light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B, and Fig. 15B shows the formation of light-emitting layer 153G.

[0203] Figures 15A and 15B show inkjet nozzles 119R, 119G, and 119B of the inkjet device. The opening diameters of the inkjet nozzles 119R, 119G, and 119B (also referred to as inkjet nozzle diameters) are several microns to several tens of microns. The part containing the inkjet nozzles is sometimes referred to as the head. To dispense the solution, the head is equipped with a solution spray control unit and also includes a piezoelectric element. The pressure element changes the volume of the ink tank connected to the inkjet nozzle to dispense the solution from the head. The volume of one droplet is often several pl to several tens of pl, depending on the inkjet nozzle diameter. Although it depends on the material, 1 pl of solution can be considered to be the amount needed to form a cube of approximately 10 µm.

[0204] When the inkjet method is used, as shown in Fig. 15A, light-emitting layers 153R, 153G, and 153B corresponding to the respective emitted colors are simultaneously formed in the openings of partition wall 110. Fig. 15B shows a cross-sectional view of light-emitting layer 153G, showing the state just before inkjet nozzles 119R, 119G, and 119B, which can move in the direction of the arrow, pass over partition wall 110. For other configurations in Figs. 15A and 15B, refer to Fig. 13 etc.

[0205] In the layer formed by the inkjet method, puddles are observed near the partition wall 110. The puddles correspond to thickened portions of the light-emitting layer 153R, the light-emitting layer 153G, and the light-emitting layer 153B near the partition wall 110. When puddles are observed, it is clear that the layer was formed by a wet method such as the inkjet method.

[0206] When formed by a wet method such as an inkjet method, at least the light-emitting layer is produced without using a metal mask, and therefore a light-emitting device having such a light-emitting layer can be said to have an MML structure.

[0207] 16A and 16B show how light-emitting layers 163R, 163G, and 163B are formed by evaporation. These correspond to light-emitting layers 153R, 153G, and 153B formed by ink-jet printing. Layer 165, which corresponds to layer 155, can also be formed by evaporation. FIG. 16A shows a state in which layer 165, which can be shared by each pixel, is divided by partition wall 110. Regarding the other configurations in FIGS. 16A and 16B, reference can be made to Embodiment 1.

[0208] 16A and 16B show a metal mask 161. The metal mask 161 has openings that overlap with pixels of the same color. In the pixel region 10 shown in FIG. 13A, the metal mask 161 has stripe-shaped openings corresponding to pixel 11R. Such a metal mask 161 can be shifted, for example, two or more times, to form light-emitting layers 163R, 163G, and 163B by the remaining pixels 11B and 11G. Specifically, a fine metal mask can be used as the metal mask 161.

[0209] When formed by vapor deposition, at least the light-emitting layer is formed using a metal mask or a fine metal mask, and therefore a light-emitting device having such a light-emitting layer can be said to have an MM structure.

[0210] In the layer formed by the vapor deposition method, no liquid pools are observed near the partition walls 110 .

[0211] The light-emitting layer is preferably formed by a wet method such as an ink-jet method, which is suitable for mass production, but may also be formed by a vapor deposition method.

[0212] 13B and 13C , layer 150 is formed. Layer 150 is located between upper electrode 216 and light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B, and has the function of being able to inject holes from upper electrode 216 to light-emitting layer 153R, light-emitting layer 153G, and light-emitting layer 153B. For example, layer 150 can have a structure having a hole injection layer, a structure having a hole transport layer, or a stacked structure of a hole injection layer and a hole transport layer.

[0213] As shown in Figures 13B and 13C, the layer 150 may be formed over the entire pixel region 10 without being divided for each pixel. The layer 150 may be formed across multiple light-emitting layers and may be shared by each pixel. The layer 150 may be formed by a wet method or a vapor deposition method. Wet methods include spin coating, inkjet printing, casting, printing, dispensing, and spraying. The layer 150 that may be shared by pixels is preferably formed by a spin coating method or a vapor deposition method.

[0214] <Upper electrode 216> The upper electrode 216 is formed on the layer 150. The upper electrode 216 corresponds to the upper electrode of a pair of electrodes that the light-emitting device has, and functions as, for example, an anode. The upper electrode 216 may also be referred to as a counter electrode.

[0215] As shown in Figures 13B and 13C, the upper electrode 216 may be formed over the entire pixel region 10 without being divided for each pixel. The upper electrode 216 is formed across multiple light-emitting layers and can be shared by each pixel. The upper electrode 216 can be formed by a wet method or a vapor deposition method. Wet methods include spin coating, inkjet printing, casting, printing, dispensing, and spraying. The upper electrode 216 that can be shared by pixels is preferably formed by a spin coating method or a vapor deposition method.

[0216] Since the upper electrode 216 functions as an anode, it is preferable to use a material with a large work function, such as an ITO film (an oxide film containing indium and tin), an oxide film containing indium and tin containing silicon, or an indium oxide film containing 2 wt % to 20 wt % zinc oxide. Furthermore, an ITO film, an oxide film containing indium and tin containing silicon, or an indium oxide film containing 2 wt % to 20 wt % zinc oxide is a transparent conductive film, allowing light generated in the light-emitting layer to pass through the upper electrode 216. Furthermore, a laminate of a transparent conductive film and a metal thin film can be used as the upper electrode 216. Examples of the metal thin film that can be used include a chromium film, a tungsten film, a Zn film, a Pt film, a Cu film, and an Al film.

[0217] 13C, the upper electrode 216 is electrically connected to the auxiliary electrode 115, so that the contact hole 18 is formed before forming the upper electrode 216. For example, after the layer 150 is formed, a mask for forming the contact hole 18 is prepared. For example, a resist mask is used as the mask.

[0218] 13B and 13C, a structure can be employed in which the light-emitting layer is not located on the upper surface of the partition wall 110. With this structure, when forming the contact hole 18, the light-emitting layer is protected on the upper surface by the layer 150 and on the side by the partition wall 110, so that the light-emitting layer is not exposed to the etching agent. In this case, the contact hole 18 can be formed using only a resist mask.

[0219] In order to reduce damage to an organic material layer or an organic compound layer such as a light-emitting layer during processing of a contact hole or the like, a sacrificial layer (sometimes referred to as a mask layer) may be formed between the layer 150 and the resist mask. By providing the sacrificial layer, the reliability of the light-emitting device can be improved. For the sacrificial layer, refer to Embodiment 1 described above.

[0220] The upper electrode 216 and the auxiliary electrode 115 can be electrically connected through the contact hole 18 formed in this manner. In a cross-sectional view of the contact hole 18, the opening in the first insulator 120 is smaller than the opening in the second insulator 121, and an end of the first insulator 120 is exposed through the opening in the second insulator 121. Furthermore, in a top view of the contact hole 18, an end of the first insulator 120 is exposed through the opening in the second insulator 121. The formation of the opening in the second insulator 121 begins before the formation of the opening in the first insulator 120, and the opening in the second insulator 121 widens. Furthermore, because the opening in the layer 150 is formed first, the opening widens, and the end of the layer 150 that defines the opening may recede to a position overlapping the upper surface of the partition wall 110. That is, the diameter of the opening in each layer gradually decreases toward the auxiliary electrode 115 below.

[0221] In the contact hole 18, a structure in which the diameter of the opening of each layer becomes smaller in stages toward the auxiliary electrode 115 is preferable because the upper electrode 216 is less likely to be cut (disconnected) at the contact hole 18. Furthermore, since the upper electrode 216 is electrically connected to the auxiliary electrode 115, it is preferable to etch a part of the surface of the auxiliary electrode 115 (referred to as over-etching). When a part of the surface is etched, a recess is formed in the surface of the auxiliary electrode 115, and using a recess is preferable because it increases the contact area between the auxiliary electrode 115 and the upper electrode 216.

[0222] Although Fig. 13C shows a structure in which layer 150 is not located within contact hole 18, layer 150 may be located within contact hole 18. For example, as shown in Fig. 14, even if layer 150 is located between auxiliary electrode 115 and upper electrode 216 in contact hole 18, it is sufficient as long as auxiliary electrode 115 and upper electrode 216 are electrically connected. In this structure, contact hole 18 is formed before layer 150 is formed. It is preferable to dispose a sacrificial layer when forming contact hole 18. For other configurations in Fig. 14, reference can be made to Fig. 1, etc.

[0223] The contact holes 18 can be provided at any desired locations. For example, as shown in Fig. 13A, one contact hole 18 may be formed for every six pixels. Since the auxiliary electrode 115 only needs to reduce the resistance of the upper electrode 216 shared in the pixel region 10, one contact hole 18 may be formed for every plurality of pixels, and there is no need to form one contact hole 18 for every pixel.

[0224] <Height of Partition 110> In the pixel region 10, the lattice-shaped partition 110 has a first region 110x along the X direction and a second region 110y along the Y direction. In one aspect of the present invention, the heights of the partitions 110 may be different, for example, the heights of the first region 110x and the second region 110y may be different. The perspective view of the pixel region 10 shown in Figure 17 shows a case where the second region 110y is higher than the first region 110x, that is, when comparing the positions of the top surfaces of the respective regions, the second region 110y is higher than the first region 110x.

[0225] The partition 110 preferably has a layered structure in which a second insulator 121 containing an organic material is located on a first insulator 120 containing an inorganic material. To vary the height of the partition 110, the first insulator 120 may correspond to the first region 110x, and the layered structure of the first insulator 120 and the second insulator 121 may correspond to the second region 110y. For example, after the first insulator 120 is formed in a lattice pattern, the second insulator 121 may be formed only in the portion corresponding to the second region 110y. For the other configuration, refer to Embodiment 1 above.

[0226] The inkjet nozzles 119R, 119G, and 119B shown in FIG. 15 and other figures can be moved along the second region 110y shown in FIG. 17. Furthermore, the second region 110y is a high partition wall, which can suppress color mixing. Suppressing color mixing is particularly advantageous when light-emitting layers of different colors are simultaneously formed for the pixels 11R, 11G, and 11B.

[0227] The first region 110x is located at the boundary between pixels of the same color. The first region 110x is a partition wall that is lower than the second region 110y. Therefore, in order to suppress color mixing, it is possible to form the light-emitting layer by the inkjet method even without the first region 110x. However, the first region 110x is preferable because it can suppress liquid unevenness between pixels of the same color.

[0228] 18A and 18B are cross-sectional views taken along the first region 110x. In these figures, a single-layer partition wall is used in the first region 110x. Specifically, a first insulator 120 is used as the single-layer partition wall.

[0229] When forming the light-emitting layer 153G by the inkjet method, the inkjet nozzle 119G is moved along the second region 110y. As a result, the light-emitting layer 153G is formed on the first insulator 120. The solution dropped from the inkjet nozzle 119G evaporates quickly in areas where there is a small amount of solution. As shown in FIG. 18A , the amount of solution on the first insulator 120 is less than in other areas, so evaporation of the solution on the first insulator 120 completes quickly. When evaporation of the solution on the first insulator 120 completes quickly, the movement of the solution between pixels that emit the same light, such as the first pixel 11G and the second pixel 11G, is reduced, thereby suppressing liquid unevenness.

[0230] 18B shows a case where the light emitting layer 163G is formed by evaporation. Since the first insulator 120 is covered with the metal mask 161, the light emitting layer 163G is not formed on the first insulator 120.

[0231] In such a low partition wall, a contact hole 18 may be formed. When forming the contact hole 18, a sacrificial layer may be formed on the light-emitting layer.

[0232] The perspective view of FIG. 17 is an example of the height of the partition wall 110, and the first region 110x may be higher than the second region 110y.

[0233] In this way, the pixel region 10 has a light-emitting device in each pixel, and the upper electrode of the light-emitting device can be electrically connected to the auxiliary electrode. The auxiliary electrode can reduce the voltage drop caused by the upper electrode. Since the auxiliary electrode is located in an area overlapping with the partition wall, it does not reduce the aperture ratio. Such an auxiliary electrode is preferably applied to a high-resolution display device with a high aperture ratio.

[0234] This embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification etc. For example, part of the structure shown in this embodiment mode may be implemented in appropriate combination with other embodiment modes described in this specification etc.

[0235] In this embodiment, a pixel region having an auxiliary electrode in a display device according to one embodiment of the present invention will be described. Specifically, the display device will be described in which the arrangement of the auxiliary electrode 115, the upper electrode 159, and the like is different from that in the above-described embodiment 1. The description of the components having the same numbers as those in the above-described embodiment 1 may be omitted in this embodiment.

[0236] 19B and 19C, auxiliary electrode 115 is formed on insulating layer 106, insulating layer 107 is newly formed on auxiliary electrode 115, and lower electrode 259 is formed on insulating layer 107. This arrangement differs from the above embodiment.

[0237] FIG. 19A shows a top view of the auxiliary electrode 115. The auxiliary electrode 115 may be arranged in a lattice pattern, as in FIG. 13A , but may also extend to the region where it overlaps with the lower electrode 259. Therefore, the auxiliary electrode 115 in FIG. 19A can have a narrower lattice spacing than that in FIG. 13A . The auxiliary electrode 115 has a region that crosses the center of the pixel 11R along the X direction. This embodiment can obtain an auxiliary electrode 115 with a larger area than the above-described embodiments. Furthermore, since it is not necessary to share the conductive material with the lower electrode 259, material selection is high, and the configuration of the auxiliary electrode 115 in this embodiment can effectively reduce the voltage drop in the upper electrode 216.

[0238] As described above, by forming the auxiliary electrode 115 on a surface different from that of the lower electrode 259, flexibility is given to the conductive material used for the auxiliary electrode 115. For example, it is preferable that a material having a lower resistivity than that of the lower electrode 259 can be used for the auxiliary electrode 115.

[0239] Furthermore, as described above, the lower electrode 259 and the surface on which it is formed can be made different, which provides a degree of freedom in the arrangement of the auxiliary electrode 115. In the above embodiment in which the lower electrode 259 and the surface on which it is formed are made the same, the auxiliary electrode 115 could not be in contact with the lower electrode 259, but in this embodiment, since the insulating layer 107 is interposed, the auxiliary electrode 115 can overlap the lower electrode 259 in a top view, and it is possible to obtain the auxiliary electrode 115 with a large area.

[0240] As shown in FIGS. 19B and 19C , the lower electrode 259 is electrically connected to the source and drain 103 through contact holes 15R, 15G, and 15B. A conductive layer 114 is preferably interposed between the lower electrode 259 and the source and drain 103. FIG. 19A shows a top view of the conductive layer 114 in addition to the auxiliary electrode 115. The conductive layer 114 is formed using the same material as the auxiliary electrode 115. By interposing the conductive layer 114, openings can be formed in the insulating layer 106 and the insulating layer 107. The openings in the insulating layer 106 are preferably formed so as not to overlap with the openings in the insulating layer 107 in a cross-sectional view. Applying the openings thus formed to the contact holes 15R, 15G, and 15B is preferable because it increases yield.

[0241] 19C , the upper electrode 216 is electrically connected to the auxiliary electrode 115 through the contact hole 18. It is preferable that a conductive layer 117 is interposed between the upper electrode 216 and the auxiliary electrode 115. The conductive layer 117 is formed using the same material as the lower electrode 259. By interposing the conductive layer 117, openings can be formed in the insulating layer 107 and the partition wall 110, respectively. Forming openings in the insulating layer 107 and the partition wall 110, respectively, is preferable to forming openings in the insulating layer 107 and the partition wall 110 collectively, since this increases the yield.

[0242] 19A to 19C, the structure other than that described above is the same as that of the above embodiment.

[0243] 20 shows a case where the layer 150 is located between the upper electrode 216 and the auxiliary electrode 115 in the contact hole 18 as in FIG. 14. Except for the fact that the layer 150 is interposed between the upper electrode 216 and the auxiliary electrode 115, the structure is the same as that of the first embodiment.

[0244] 21A and 21B show the formation of light-emitting layers 153R, 153G, and 153B using the inkjet method as in FIGS. 15A and 15B. In FIG. 21A, a conductive layer 114 is interposed between the lower electrode 259 and the source and drain 103. In FIG. 21B, a conductive layer 117 electrically connected to an auxiliary electrode 115 is provided. FIG. 21B is a cross-sectional view before the upper electrode 216 is formed, and the auxiliary electrode 115 shown in the figure is electrically connected to the upper electrode 216 via the conductive layer 117. The other configurations are the same as those in the first embodiment.

[0245] 22A and 22B show the formation of light-emitting layers 163R, 163G, and 163B using a vapor deposition method as in FIGS. 16A and 16B. In FIG. 22A, a conductive layer 114 is interposed between the lower electrode 259 and the source and drain 103. In FIG. 22B, a conductive layer 117 electrically connected to an auxiliary electrode 115 is provided. FIG. 22B is a cross-sectional view before the upper electrode 216 is formed, and the auxiliary electrode 115 shown in the figure is electrically connected to the upper electrode 216 via the conductive layer 117. The other configurations are the same as those in the first embodiment.

[0246] In this embodiment as well, the heights of the partition walls 110 may be made different as shown in the perspective view of FIG.

[0247] 23A and 23B show cross-sectional views along the first region 110x as in Figures 18A and 18B. For example, the first region 110x has a first insulator 120.

[0248] Figure 23A shows how, when forming light-emitting layer 153G by inkjet printing, inkjet nozzle 119G is moved along second region 110y. As a result, light-emitting layer 153G is formed on first insulator 120. Figure 23A also shows a conductive layer 117 electrically connected to auxiliary electrode 115. Figure 23A is a cross-sectional view before upper electrode 216 is formed, and auxiliary electrode 115 shown in the figure is electrically connected to upper electrode 216 via conductive layer 117. The rest of the configuration is the same as in embodiment 1 above.

[0249] 23B shows the case where the light-emitting layer 163G is formed by vapor deposition. Because the first insulator 120 is covered with the metal mask 161, the light-emitting layer 163G is not formed on the first insulator 120. Also, in FIG. 23B, a conductive layer 117 electrically connected to the auxiliary electrode 115 is provided. FIG. 23B is a cross-sectional view before the upper electrode 216 is formed, and the auxiliary electrode 115 shown in the figure is electrically connected to the upper electrode 216 via the conductive layer 117. The other configurations are the same as those in the first embodiment.

[0250] In this way, the pixel region 10 has a light-emitting device in each pixel, and the upper electrode of the light-emitting device can be electrically connected to the auxiliary electrode. The auxiliary electrode can reduce the voltage drop caused by the upper electrode. Since the auxiliary electrode is located below the partition wall, it is preferable to apply it to a high-resolution display device with a high aperture ratio.

[0251] This embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification etc. For example, part of the structure shown in this embodiment mode may be implemented in appropriate combination with other embodiment modes described in this specification etc.

[0252] Embodiment 5 In this embodiment, a light-emitting device according to one embodiment of the present invention will be described.

[0253] 24A , the light-emitting device 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 can be composed of a plurality of functional layers, such as a layer 4420, a light-emitting layer 4411, and a layer 4430, and a partition wall 110 is positioned for the layers formed by a wet method. For example, when the light-emitting layer 4411 is formed by a wet method, the partition wall 110 is provided to separate the light-emitting layer 4411. Although not shown, the partition wall 110 may have a first region and a second region with different heights as in the above embodiment.

[0254] The light-emitting layer 4411 may be, for example, a functional layer having a light-emitting material.

[0255] 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, the layer 4430 corresponds to the layer 150 in Embodiment 1 and the like. The layer 4430 may be formed using, for example, a hole injection layer, a hole transport layer, or the like. The hole injection layer may be referred to as HIL (an abbreviation for Hole Injection Layer). The hole transport layer may be referred to as HTL (an abbreviation for Hole Transport Layer). The layer 4430 may include either a hole injection layer or a hole transport layer. The layer 4420 corresponds to the layer 155 in Embodiment 1 and the like. The layer 4420 may be formed using, for example, an electron injection layer, an electron transport layer, or the like. The electron injection layer may be referred to as EIL (an abbreviation for Electron Injection Layer). The electron transport layer may be referred to as ETL (Electron Transport Layer). The layer 4420 may include either an electron injection layer or an electron transport layer.

[0256] In FIG. 24A , the light-emitting layer 4411 is formed on the layer 4430 located within the partition 110 by a wet method such as an inkjet method or a vapor deposition method. The light-emitting layer 4411 corresponds to the light-emitting layer 153R, the light-emitting layer 153G, and the light-emitting layer 153B in the above-described Embodiment 1, etc. Alternatively, the light-emitting layer 4411 corresponds to the light-emitting layer 163R, the light-emitting layer 163G, and the light-emitting layer 163B in the above-described Embodiment 1, etc. The lower electrode 672 and the upper electrode 688 can be formed by a vapor deposition method, a CVD method, or a sputtering method. The layer 4430 and the layer 4420 can be formed by a wet method or a vapor deposition method. Among these, the layer 4420 and the upper electrode 688 can be shared among a plurality of light-emitting devices. The shared layer is formed over the entire pixel region. The shared layer is formed over the partition 110, but if a step discontinuity due to the partition 110 is to be avoided, the shared layer may be thickened. When there is a limit to the thickness of the film, the solution or the like used for inkjet printing may be adjusted so that the light-emitting layer 4411 formed below is filled to a height of 2 / 3 or more and less than 1 times the height of the partition wall 110 .

[0257] Next, a more specific configuration of Fig. 24A is shown in Fig. 24B. The light-emitting device 20 shown in Fig. 24B has a layer 4430-1 on a lower electrode 672, a layer 4430-2 on the layer 4430-1, a light-emitting layer 4411 on the layer 4430-2, a layer 4420-1 on the light-emitting layer 4411, a layer 4420-2 on the layer 4420-1, and an upper electrode 688 on the layer 4420-2, and a partition wall 110 is positioned relative to the layers formed by a wet method. For example, when the light-emitting layer 4411 is formed by a wet method, the partition wall 110 is provided to separate the light-emitting layer 4411. Although not shown, the partition wall 110 may have a first region and a second region with different heights.

[0258] For example, if the lower electrode 672 is an anode and the upper electrode 688 is a cathode, layer 4430-1 functions as a hole injection layer, layer 4430-2 functions as a hole transport layer, layer 4420-1 functions as an electron transport layer, and layer 4420-2 functions as an electron injection layer.

[0259] Such a light-emitting device makes it possible to efficiently inject carriers (holes and electrons) into the light-emitting layer 4411 and increase the efficiency of carrier recombination in the light-emitting layer 4411. Note that the layers included between the light-emitting layer 4411 and the lower electrode 672 and the layer included between the light-emitting layer 4411 and the upper electrode 688 are not limited to these, and may include a carrier blocking layer, an exciton blocking layer, or the like as appropriate. Furthermore, a layer having both a carrier transport function and a carrier injection function may be used.

[0260] In FIG. 24B , the light-emitting layer 4411 is formed on the layer 4430-2 inside the partition 110 by a wet method such as an inkjet method or a vapor deposition method. The lower electrode 672 and the upper electrode 688 can be formed by a vapor deposition method, a CVD method, or a sputtering method. The layers 4430-1, 4430-2, 4420-1, and 4420-2 can be formed by a wet method or a vapor deposition method. Among these, the layers 4420-1, 4420-2, and the upper electrode 688 can be shared among multiple light-emitting devices. The shared layer is formed over the entire pixel region. The shared layer is formed over the partition 110, but if a step discontinuity due to the partition 110 is to be avoided, the shared layer may be thickened. If there is a limit to the thickness, the solution used during inkjet printing may be adjusted so that the light-emitting layer 4411 formed below is filled to a height of 2 / 3 or more and less than 1 times the height of the partition 110.

[0261] Next, modifications of Figures 24A and 24B are shown in Figures 24C1 and 24C2. In Figure 24C1, multiple light-emitting layers (first light-emitting layer 4412, second light-emitting layer 4413, and third light-emitting layer 4414) are provided between layer 4420 and layer 4430. In Figure 24C2, multiple light-emitting layers (first light-emitting layer 4412 and second light-emitting layer 4413) are provided between layer 4420 and layer 4430. Note that the light-emitting layers are distinguished from one another by assigning ordinal numbers from the bottom. In addition, partitions 110 are positioned for layers formed by a wet process. For example, when multiple light-emitting layers are all formed by a wet process, partitions 110 are provided to separate these layers. Although not shown, partitions 110 may have first and second regions with different heights.

[0262] The light-emitting materials contained in these multiple light-emitting layers can be selected from light-emitting materials of the same color or 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. When light-emitting materials of different colors are selected, selecting light-emitting materials that have a complementary color relationship can provide a light-emitting device that emits white light. For example, in FIG. 24C2, white light can be emitted from the light-emitting device 20 by using light-emitting materials whose emission color is complementary to that of the first light-emitting layer 4412 and the second light-emitting layer 4413.

[0263] Although FIGS. 24C1 and 24C2 show structures in which three and two light-emitting layers are stacked, respectively, four or more layers may be used.

[0264] When white light is emitted and a full color display is desired, a method is available in which desired colors such as red (R), blue (B), and green (G) are obtained using color filters or color conversion layers.

[0265] In FIGS. 24C1 and 24C2, a full-color display is possible by painting each light-emitting device with a different luminescent color.

[0266] 24C1 and 24C2, multiple light-emitting layers, such as the light-emitting layer 4411, are formed on the layer 4430 within the partition 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 these, the layer 4420 and the upper electrode 688 may be shared among multiple light-emitting devices. The shared layer is formed over the entire pixel region. The shared layer is formed over the partition 110, but if a step discontinuity due to the partition 110 is to be avoided, the shared layer may be thickened. If there is a limit to the thickness, the solution used during inkjet printing may be adjusted so that the first light-emitting layer 4412 formed below is filled to a height of 2 / 3 or more and less than 1 times the height of the partition 110.

[0267] 24C1 and 24C2, the layer 4420 and the layer 4430 may have a laminated structure consisting of two or more layers, as shown in FIG. 24B.

[0268] Next, modifications of FIG. 24C2 are shown in FIGS. 24D1 and 24D2. Both FIGS. 24D1 and 24D2 show examples in which light-emitting units are stacked. In FIGS. 24D1 and 24D2, a first light-emitting unit 686a and a second light-emitting unit 686b are provided, with an intermediate layer (sometimes referred to as a charge generation layer) 690 between them. The first light-emitting unit 686a includes a layer 4430-1, a first light-emitting layer 4412, and a layer 4420-1. The second light-emitting unit 686b includes a layer 4430-2, a second light-emitting layer 4413, and a layer 4420-2. A partition 110 is positioned for each layer formed by a wet process. For example, when the first light-emitting layer 4412 and the second light-emitting layer 4413 are formed by a wet process, a partition 110 is provided to separate the light-emitting layers. Although not shown, the partition wall 110 has a first region and a second region with different heights. The light-emitting layers are distinguished from one another by assigning ordinal numbers from the bottom.

[0269] 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.

[0270] Intermediate layer 690 shown in Figure 24D1 has a dopant material. For example, it has a donor material similar to layer 4420-1 and an acceptor material similar to layer 4430-2. In intermediate layer 690, the layer having the donor material is located on the layer 4420-1 side, and the layer having the acceptor material is located on the layer 4430-2 side.

[0271] Intermediate layer 690a shown in FIG. 24D2 is a layer having a donor material similar to layer 4420-1, and intermediate layer 690b is a layer having an acceptor material similar to layer 4430-2, and these can be distinguished.

[0272] 24D1 and 24D2, as in FIG. 24C2, 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 to be complementary colors, a light-emitting device that emits white light can be obtained.

[0273] In the cases of FIGS. 24D1 and 24D2 where white light is emitted and full color display is desired, a color filter or color conversion layer may be used, as in FIG. 24C2 and the like.

[0274] In FIGS. 24D1 and 24D2, similarly to FIG. 24C2 etc., full-color display is possible by painting each light-emitting device with a different luminescent color (red (R), blue (B), green (G)).

[0275] 24 , the color purity can be further improved by providing a microcavity structure. The microcavity structure has a structure in which the film thickness of the lower electrode 672 or the film thickness of the light-emitting layer is varied for each emitted color. When the lower electrode 672 has a layered structure of a first conductive film and a second conductive film on the first conductive film, it is easier to provide the microcavity structure by varying the film thickness of the second conductive film.

[0276] Here, a specific example of the configuration of the light-emitting device will be described.

[0277] The light-emitting device 20 has at least a light-emitting layer. The light-emitting device 20 may further have a layer other than the light-emitting layer, which layer contains a substance with high hole-injection properties, a substance with high hole-transport properties, a hole-blocking material, a substance with high electron-transport properties, an electron-blocking material, a substance with high electron-injection properties, or a bipolar substance (a substance with high electron-transport properties and high hole-transport properties).

[0278] <Hole Injection Layer> The hole injection layer is a layer containing a substance with high hole injection properties, and is a layer that can inject holes from the anode to the hole transport layer.

[0279] Specific materials with high hole injection properties can be formed from phthalocyanine complex compounds, aromatic amine compounds, or polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS).

[0280] A hole injection layer different from the above may be formed from a substance having acceptor properties, which can extract electrons from an adjacent hole transport layer (or hole transport material) by applying a voltage between electrodes.

[0281] Examples of organic compounds that can be used as acceptors include those having electron-withdrawing groups (e.g., halogen groups, cyano groups, etc.). Compounds in which electron-withdrawing groups are bonded to fused aromatic rings containing multiple heteroatoms, such as 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated as HAT-CN), are particularly thermally stable and preferred. Radialene derivatives [3] that have 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.

[0282] As the substance having acceptor properties, inorganic compounds such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. can be used in addition to the organic compounds described above.

[0283] 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. −６ cm ２ It is preferable that the material has a hole mobility of 1 / Vs or more.

[0284] Examples of materials having hole transport properties that can be used in composite materials include organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymeric compounds (oligomers, dendrimers, polymers, etc.). In other words, the materials having hole transport properties that can be used in composite materials are preferably organic compounds having a fused aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. Examples of fused aromatic hydrocarbon rings include an anthracene ring and a naphthalene ring. Examples of π-electron-rich heteroaromatic rings are preferably fused aromatic rings containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton. Specifically, examples of fused aromatic rings include a carbazole ring, a dibenzothiophene ring, and rings in which an aromatic ring or a heteroaromatic ring is fused to one of these rings. Other aromatic amine compounds may also be used as materials having hole transport properties.

[0285] <Hole transport layer> The hole transport layer is a layer that transports holes injected from the anode by the hole injection layer to the light emitting layer. The hole transport layer is a layer containing a hole transport material. The hole transport material is a material containing 1×10 −６ cm ２ A substance having a hole mobility of 1 / Vs or more is preferred. As the hole-transporting material, a material having a high hole-transporting property, such as a π-electron-rich heteroaromatic compound or an aromatic amine, is preferred. Note that any substance having a higher hole-transporting property than an electron-transporting property can be used as the hole-transporting material.

[0286] 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.

[0287] <Electron Transport Layer> 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 containing 1×10 −６ cm ２A substance having an electron mobility of 1 / Vs or more is preferred. As such an electron transporting material, a metal complex and an organic compound having a π-electron-deficient heteroaromatic ring skeleton are preferred. Note that other substances can also be used as the electron transporting material as long as they have a higher electron transporting property than holes.

[0288] Specifically, materials with high electron transport properties can be used, 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 π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds. 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 (e.g., pyrimidine or pyrazine) skeleton or a triazine skeleton have high electron transport properties and contribute to reducing driving voltage.

[0289] <Electron Injection Layer> 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 materials 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, which contains an alkali metal, alkaline earth metal, or a compound thereof.

[0290] 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 may 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, pyridazine ring), and a triazine ring, such as 4,7-diphenyl-1,10-phenanthroline (abbreviation: BPhen) or 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), may be used.

[0291] <Light-emitting layer> The light-emitting layer is a layer containing 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 a color such as 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.

[0292] As the light-emitting substance, a fluorescent material, a phosphorescent material, a substance that exhibits thermally activated delayed fluorescence (thermally activated delayed fluorescence (TADF) material), a quantum dot material, or the like can be used.

[0293] While known fluorescent materials can be used, 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.

[0294] 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.

[0295] 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.

[0296] Among skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good 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 preferred because they are stable and good reliability. Note that a dibenzofuran skeleton is preferred as the furan skeleton, and a dibenzothiophene skeleton is preferred as the thiophene skeleton. Furthermore, 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 as the pyrrole skeleton.

[0297] In addition, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of the π-electron-deficient heteroaromatic ring and the π-electron-rich heteroaromatic ring. Examples of the π-electron-rich skeleton include an aromatic amine skeleton and a phenazine skeleton. 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, and a sulfone skeleton.

[0298] 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 material and the electron-transporting material described above may be used. Furthermore, as the one or more organic compounds, a bipolar material or a TADF material may be used.

[0299] The light-emitting layer preferably includes, for example, a phosphorescent material and a hole-transporting material and an electron-transporting material that are a combination that easily forms an exciplex. This configuration allows for efficient emission using Exciplex-Triple 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, allowing for efficient emission. This configuration simultaneously enables high efficiency, low-voltage operation, and long life of the light-emitting device.

[0300] In one embodiment of the present invention, the light-emitting layer is formed by a wet method such as an inkjet method. A coating composition in which the above-mentioned various materials are dissolved or dispersed in a solvent can be used. In this case, various organic solvents can be used. Furthermore, a material such as a polymer material, a low-molecular-weight material, or a dendrimer having a desired function can be mixed or dispersed or dissolved in a solvent and used as an ink material. Polymer materials are sometimes referred to as polymer materials.

[0301] In addition, when it is desired to form the light-emitting layer using a polymer, a composition containing one or more types of 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.

[0302] The composition may contain organic compounds having other functions, such as surfactants or viscosity adjusting substances.

[0303] 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 polyparaphenylene vinylene derivatives (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 (polyvinylcarbazole; PVK).

[0304] 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 organic solvents for the composition. 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 composition from deteriorating due to oxidation or the like. In addition, in consideration of the uniformity of the film or the uniformity of the film thickness after production, it is preferable for the boiling point to be 100°C or higher, and toluene, xylene, and mesitylene are more preferred.

[0305] <Material of Layer 4430> 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 shared by each pixel, the layer 4430 can be formed by a spin coating method or the like after the partition wall 110 is formed.

[0306] 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.

[0307] When the 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.

[0308] 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, or 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, or an imidazole skeleton. Multiple bonds via arylamines or heteroarylamines are preferred for improved 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.

[0309] As the secondary amine, for example, an organic compound represented by the following general formula (G1) is preferable.

[0310]

[0311] However, in the above general formula (G1), Ar １１ ~Ar １３ At least one of Ar represents hydrogen; １４ ~Ar １７ represents a substituted or unsubstituted aromatic ring having 6 to 14 carbon atoms; Ar １４ ~Ar １７ represents a substituted or unsubstituted aromatic ring having 6 to 14 carbon atoms. 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 １７may be bonded to each other to form a ring. Examples of aromatic rings having 6 to 14 carbon atoms include a benzene ring, a bisbenzene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, and an anthracene ring. p represents an integer of 0 to 1,000, preferably 0 to 3. The molecular weight of the organic compound represented by the general formula (G1) is preferably 100,000 or less.

[0312] As the tertiary amine, for example, an organic compound represented by the following general formula (G2) is preferable.

[0313]

[0314] However, in the above general formula (G2), Ar ２１ ~Ar ２３ represents a substituted or unsubstituted aryl group having 6 to 14 carbon atoms, and these may be bonded to each other to form a ring. ２１ ~Ar ２３ When 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.

[0315] 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.

[0316]

[0317]

[0318]

[0319]

[0320]

[0321] An amine compound can be mixed with a sulfonic acid compound and used in a solution. Mixing with a sulfonic acid compound facilitates carrier generation and improves conductivity. Mixing with a sulfonic acid compound 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 such as those represented by the above structural formulas (Am2-1), (Am2-22) to (Am2-28), or (Am2-31) as the amine compound improves compatibility and is therefore preferred.

[0322] A thiophene derivative may be used instead of a 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). Mixing a thiophene derivative with a sulfonic acid compound facilitates carrier generation and improves conductivity. Mixing with a sulfonic acid compound is sometimes referred to as p-doping.

[0323]

[0324] Sulfonic acid compounds are materials that exhibit acceptor properties. Examples of sulfonic acid compounds include arylsulfonic acids. The arylsulfonic acid may have 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 present in the arylsulfonic acid may be a substituted or unsubstituted aryl group having 6 to 16 carbon atoms. Examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthryl group, or a pyrenyl group. The naphthyl group is particularly preferred due to its excellent solubility and transportability in organic solvents. The arylsulfonic acid may also have multiple aryl groups. Furthermore, when the arylsulfonic acid has a fluorine-substituted aryl group, the LUMO level can be adjusted to a deep (largely negative) level, which is preferable. 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.

[0325] Specific examples of compounds having arylsulfonic acid (arylsulfonic acid compounds) are preferably organic compounds represented by the following structural formulas (S-1) to (S-15). Polymers having a sulfo group, such as poly(4-styrenesulfonic acid) (PSS), can also be used. The use of an arylsulfonic acid compound allows it to accept electrons from an electron donor with a shallow HOMO (such as an amine compound, a carbazole compound, or a thiophene compound), and mixing it with an electron donor can provide hole injection or hole transport properties from an electrode. The use of a fluorine compound as the arylsulfonic acid compound allows it to adjust its LUMO level to a deeper level (a more negative energy level).

[0326]

[0327]

[0328]

[0329]

[0330] 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.

[0331]

[0332]

[0333] In addition to arylsulfonic acid compounds, cyano compounds such as tetracyanoquinodimethane compounds can also be used as electron acceptors.Specific examples include 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) and dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN6).

[0334] 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 process.

[0335] When a layer formed by a wet method 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, a signal is observed around m / z=80 in the negative mode. m / z=80 corresponds to the SO ３ The signal is derived from anions. On the other hand, signals derived from amine monomers are difficult to observe 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 ability. If analytical results such as the above signals are obtained in a light-emitting device capable of emitting light, it is clear that the layer has sufficient hole transport ability. The absence of observation of amine or other skeletons responsible for hole transport ability suggests that the above monomers are bonded to each other to form a film of a polymer compound. Such analytical results indicate that the layer was formed by a wet method.

[0336] The sulfonic acid compounds represented by the structural formula (S-1) or (S-2) are preferred because they contain many sulfo groups, can form three-dimensional bonds with amine compounds, and tend to stabilize the film quality. In addition to the signal at m / z=80, a signal at m / z=901 is observed in the negative mode when the layer is prepared using the aryl sulfonic acid compound. A signal at m / z=328 is also observed as a product ion.

[0337] <Light-emitting material> Note that in the light-emitting device of one embodiment of the present invention, an iridium complex represented by the following structural formula is preferably used as the 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.

[0338]

[0339] It is known that when an emitting layer containing the iridium complex represented by the above structural formula is measured by ToF-SIMS in the positive mode, a signal appears at m / z = 1676 or at product ions m / z = 1181 and m / z = 685.

[0340] When the intermediate layer is a single layer as shown in Fig. 13D1, it is sufficient that it contains an acceptor material and a donor material. When the intermediate layer is a double layer as shown in Fig. 13D2, it is sufficient that it has an organic compound layer containing an acceptor material and an organic compound layer containing a donor material.

[0341] 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.

[0342] 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, as an organic acceptor material, a compound having an electron-withdrawing group (a halogen group or a cyano group), such as a quinodimethane derivative, a chloranil derivative, or a hexaazatriphenylene derivative, can be used. For example, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F ４Examples of organic acceptor materials that can be used include 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile, 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-TCCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. Among organic acceptor materials, compounds such as HAT-CN in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms are particularly suitable because of their high acceptor properties and stable film quality against heat. In addition, [3]radialene derivatives having an electron-withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) are preferred because they have extremely high electron-accepting properties. Specifically, α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile], etc. can be used.

[0343] 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.

[0344] 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.

[0345] This embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification etc. For example, part of the structure shown in this embodiment mode may be implemented in appropriate combination with other embodiment modes described in this specification etc.

[0346] Embodiment 6 In this embodiment, a configuration example and a driving method example of a pixel circuit according to one embodiment of the present invention will be described.

[0347] 25A includes a transistor M1, a transistor M2, a capacitor C1, and a light-emitting device EL. The pixel circuit PIX1 is electrically connected to a wiring SL, a wiring GL, a wiring AL, and a wiring CL.

[0348] 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 a source and drain electrically connected to a wiring AL and the other electrically connected to the anode of the light-emitting device EL. The capacitor C1 has the other electrode electrically connected to the anode of the light-emitting device EL. The light-emitting device EL has a cathode electrically connected to a wiring CL.

[0349] The transistor M1 can also be called a selection transistor and functions as a switch for controlling selection and non-selection of a pixel. The LTPS transistor or the OS transistor described in the above embodiment can be used as the transistor M1, but an OS transistor is preferable.

[0350] The transistor M2 can also be called a driving transistor and has a function of controlling a current flowing through the light-emitting device EL. The LTPS transistor, the OS transistor, or the like described in the above embodiment can be used as the transistor M2, but an LTPS transistor is preferable.

[0351] The capacitor C1 functions as a storage capacitor and has a function of holding the gate potential of the transistor M2. A capacitive element such as an MIM capacitor may be applied as the capacitor C1, or a capacitance between wirings or a gate capacitance of a transistor may be used as the capacitor C1.

[0352] 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 G that functions as the gate of the transistor. A constant potential is supplied to the wiring AL and the wiring CL. The wiring AL and the wiring CL can each be formed using a conductive layer or a conductive layer G, or a conductive layer and a conductive layer G. The wiring AL and the wiring CL can each be formed using the same conductive layer as the conductive layer or the same conductive layer as the conductive layer G.

[0353] The anode side of the light emitting device 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.

[0354] 25B has a configuration in which a transistor M3 is added to the pixel circuit PIX1. A wiring V0 is electrically connected to the pixel circuit PIX2. The LTPS transistor or the OS transistor described in the above embodiment can be used as the transistor M3, but an LTPS transistor is preferable.

[0355] 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 device EL, and the other electrically connected to the wiring V0.

[0356] A constant potential is applied to the wiring V0 when data is written to the pixel circuit PIX2, thereby making it possible to suppress variations in the gate-source voltage of the transistor M2.

[0357] The pixel circuit PIX3 shown in FIG. 25C is an example in which transistors having a pair of gates electrically connected are applied to the transistors M1 and M2 of the pixel circuit PIX1. The pixel circuit PIX4 shown in FIG. 25D is an example in which transistors having a pair of gates electrically connected are applied to 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 applied to all the transistors here, this is not a limitation. Alternatively, transistors having a pair of gates electrically connected to different wirings may be applied. For example, reliability can be improved by using a transistor in which one of the gates is electrically connected to the source.

[0358] 26A has a configuration in which a transistor M4 is added to the pixel circuit PIX2. Three wirings (a wiring GL1, a wiring GL2, and a wiring GL3) that function as gate lines are electrically connected to the pixel circuit PIX5. The LTPS transistor or the OS transistor described in the above embodiment can be used as the transistor M4, but an LTPS transistor is preferable.

[0359] 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 can be formed using the same conductive layer as the conductive layer G, or the same conductive layer as the conductive layer G, or a combination of these. The wiring V0 may be arranged to intersect with the wiring AL.

[0360] By simultaneously turning on the transistors M3 and M4, the source and gate of the transistor M2 have the same potential, and the transistor M2 can be turned off. This forcibly cuts off the current flowing through the light-emitting device EL. This pixel circuit is suitable for use in a display method in which display periods and off periods are alternately provided.

[0361] 26B is an example in which a capacitor C2 is added to the pixel circuit PIX5. The capacitor C2 functions as a storage capacitor.

[0362] 26C and 26D are examples in which transistors each having a pair of gates are applied to the pixel circuit PIX5 or PIX6. Transistors M1, M3, and M4 have a pair of gates electrically connected to each other, and transistor M2 has one gate electrically connected to its source.

[0363] 27A includes a transistor M1, a transistor M2, a capacitor C1, and a light-emitting device EL. The pixel circuit PIX1 is electrically connected to a wiring SL, a wiring GL, a wiring AL, and a wiring CL.

[0364] 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 a source and drain electrically connected to a wiring CL, and the other electrically connected to the cathode of the light-emitting device EL. The other electrode of the capacitor C1 is electrically connected to the other of the source and drain of the transistor M2. The light-emitting device EL has an anode electrically connected to a wiring AL.

[0365] The transistor M1 can also be called a selection transistor and functions as a switch for controlling the selection / non-selection of a pixel. The transistor M2 can also be called a drive transistor and has a function of controlling the current flowing through the light-emitting device EL. The transistor M2 is a drive element. The capacitor C1 functions as a storage capacitor and has a function of holding the gate potential of the transistor M2. A capacitive element such as an MIM capacitor may be applied as the capacitor C1, or the capacitance between wirings or the gate capacitance of a transistor may be used as the capacitor C1.

[0366] 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 G that functions as the gate of the transistor. A constant potential is supplied to the wiring AL and the wiring CL. The wiring AL and the wiring CL can each be formed using a conductive layer or a conductive layer G, or a conductive layer and a conductive layer G. The wiring AL and the wiring CL can each be formed using the same conductive layer as the conductive layer or the same conductive layer as the conductive layer G.

[0367] The anode side of the light emitting device 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.

[0368] The pixel circuit PIX2 shown in FIG. 27B 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. This makes it possible to increase the current that can flow 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. Furthermore, transistors having a pair of gates electrically connected to different wirings may also be used. For example, reliability can be improved by using a transistor in which one of the gates is electrically connected to the source.

[0369] 28A has a configuration in which a transistor M3 is added to the above-described PIX1. In addition, the pixel circuit PIX3 is electrically connected to wirings (a wiring GL1 and a wiring GL2) that function as two gate lines.

[0370] The gate of the transistor M3 is electrically connected to a wiring GL2, one of the source and drain of the transistor M2 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. The wiring V0 can be formed using the same conductive layer as the conductive layer G, the same conductive layer as the conductive layer G, or a combination of these. The wiring V0 may be arranged to intersect with the wiring AL.

[0371] By turning on transistor M3, the source and gate of transistor M2 have the same potential, making it possible to turn off transistor M2. This forcibly cuts off the current flowing through light-emitting device EL. This pixel circuit is suitable for use in a display method in which display periods and off periods are alternately provided.

[0372] 28B is an example in which transistors each having a pair of gates are applied to the pixel circuit PIX3. Transistors M1, M2, and M3 have a pair of gates electrically connected to each other.

[0373] [Driving Method Example] An example of a driving method for a display device to which the pixel circuit PIX5 is applied will be described below. Note that the same driving method can also be applied to the pixel circuits PIX6, PIX7, and PIX8.

[0374] 29 is a timing chart illustrating a driving method of a display device using the pixel circuit PIX5. The timing chart illustrates the transition of potentials 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 timing chart also illustrates the timing of signals applied to the wirings SL, which function as source lines.

[0375] 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.

[0376] 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.

[0377] Subsequently, the lighting period of the k+1th row begins, and data is written in the same manner as above.

[0378] 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 device EL. All pixels located on the kth row are turned off. The pixels on the kth row remain off until the next light-on period.

[0379] Next, the process shifts to the off period of the k+1th row, and all the pixels of the k+1th row are turned off in the same manner as above.

[0380] 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. Duty driving can reduce the afterimage phenomenon when displaying moving images, thereby realizing a display device with high moving image display performance. In particular, in VR devices, reducing afterimages can alleviate so-called VR sickness.

[0381] In duty driving, 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. Note that the duty ratio can be freely set and can be adjusted as appropriate within a range of, for example, more than 0% and less than 100%.

[0382] This embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification etc. For example, part of the structure shown in this embodiment mode may be implemented in appropriate combination with other embodiment modes described in this specification etc.

[0383] Embodiment 7 In this embodiment, a display device according to one embodiment of the present invention will be described.

[0384] 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 reproduction devices.

[0385] [Display Device 400A1] FIG. 30 shows a perspective view of the display device 400A1, and FIG. 31A shows a cross-sectional view of the display device 400A1. The display device 400A1 has a display portion 462, a circuit 464, wiring 465, and the like. The display portion 462 includes a pixel region. FIG. 30 shows an example in which an IC 473 and an FPC 472 are mounted on the display device 400A1. Therefore, the configuration shown in FIG. 30 can also be said to be a display module including the display device 400A1, an IC (integrated circuit), and an FPC.

[0386] The circuit 464 can be, for example, a scanning line driver circuit.

[0387] 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.

[0388] 30 shows an example in which an IC 473 is provided by a chip-on-glass (COG) method or a chip-on-film (COF) 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 400A1 and the display module may have a structure in which an IC is not provided.

[0389] The cross-sectional view of Fig. 31A includes the FPC 472, the circuit 464, the display unit 462, and an end portion of the display device 400A1. The end portion of the display device 400A1 is an area located outside the display unit 462. The area to which the FPC 472 is attached also corresponds to the end portion. Fig. 31A shows the end portion facing the FPC 472.

[0390] The display device 400A1 has a structure in which a support substrate 411 is bonded to a resin layer 413 using an adhesive layer 412. A glass substrate or a plastic substrate can be used as the support substrate 411. A structure using a plastic substrate can be lighter than a structure including a glass substrate. In order to prevent intrusion of impurity elements from the adhesive layer 412 or the resin layer 413, an insulating layer 415 and an insulating layer 416 are provided. The insulating layer 415 and the insulating layer 416 are preferably formed using an inorganic material.

[0391] The inorganic material contained in the insulating layer 415 and the insulating layer 416 may include 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. The inorganic material contained in the insulating layer 415 is preferably different from the inorganic material contained in the insulating layer 416.

[0392] In Fig. 31A, the opposing side has an opposing substrate 443 bonded via an adhesive layer 442. That is, the display device 400A1 has a structure in which the support substrate 411 and the opposing substrate 443 are bonded together. In Fig. 30, the opposing substrate 443 is indicated by a dashed line. The opposing substrate 443 can be a glass substrate or a plastic substrate. A structure using a plastic substrate can be made lighter than a structure having a glass substrate.

[0393] The resin layer 413 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, or the like.

[0394] Adhesive layer 412 or adhesive layer 442 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. If resin layer 413 has sufficient adhesive function, adhesive layer 412 can be omitted.

[0395] The adhesive layer 442 on the opposing side functions as a sealant for the light-emitting device. Such a seal structure is referred to as a solid seal structure. In addition to the solid seal structure, a hollow seal structure or the like can also be applied. The hollow seal structure will be described later.

[0396] 31A includes a transistor 101. The above embodiment modes may be referred to for the transistor 101. In this embodiment mode, a back gate 420 is provided in addition to the transistor 101. An insulating layer 421 is provided over the back gate 420. The back gate 420 is not necessarily provided as in the above embodiment modes.

[0397] The light-emitting device exemplified in the above embodiment mode is provided over the transistor 101, and in this embodiment mode, an insulating layer 440 is provided over the upper electrode 159. The insulating layer 421 and the insulating layer 440 are preferably formed using an inorganic material, which can prevent the intrusion of moisture in addition to impurity elements.

[0398] The inorganic material contained in the insulating layer 421 and the insulating layer 440 preferably contains 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. The insulating layer 440 preferably has a stacked structure of at least three layers. In the stacked structure of three or more layers, at least two or more inorganic materials are preferably used.

[0399] Light emitted from the light-emitting device is emitted to the opposing substrate 443 side as indicated by the dashed line. A structure in which light is emitted to the opposing substrate 443 side is referred to as a top emission structure. In the case of a top emission structure, it is preferable that the opposing substrate 443 be made of a material that is highly transparent to visible light.

[0400] Color filter layers (also referred to as colored layers) are arranged on the opposing substrate 443 in correspondence with the light-emitting layers 153R, 153G, and 153B. The color filter layers include a color filter layer 444R capable of exhibiting red, a color filter layer 444G capable of exhibiting green, and a color filter layer 444B capable of exhibiting blue, corresponding to the respective emitted colors. A light-shielding layer 434 is arranged between the color filter layers. The light-shielding layer is also referred to as a black matrix.

[0401] A light-shielding layer is also provided in the circuit 464. The transistor provided in the circuit 464 can be manufactured using the same material and in the same process as the transistor 101 in the display portion 462.

[0402] FIG. 31A shows a region 431 as an end portion. A light-shielding layer is also provided at the end portion. The region 431 has a structure in which the conductive layers 432, 433, and 435 are in contact with each other, i.e., a structure sealed by these layers. The conductive layer 432 is made of the same material as the source and drain 103. The conductive layer 433 is made of the same material as the auxiliary electrode 115. The conductive layer 435 is made of the same material as the upper electrode 159. Openings are provided in each insulating layer so that the above-mentioned conductive films can be in contact with each other. For example, an opening is provided in the insulating layer 106, and the conductive layer 432 has a region in contact with the conductive layer 433 at the opening. Furthermore, openings are provided in the first insulator 120 and the second insulator 121, and the conductive layer 433 has a region in contact with the conductive layer 435 at the opening. At the end portion, an insulating layer 440 is provided on the conductive layer 435, and an adhesive layer 442 is provided on the insulating layer 440.

[0403] The transistor 101 has a back gate 420 and has a structure in which a semiconductor layer is sandwiched between two gates. The two gates may be connected and the transistor may be driven by supplying the same signal to them. 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.

[0404] 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 may be used. Figure 31B shows a structure of a transistor 101 in which a gate insulating layer is patterned in a region that extends beyond the gate and overlaps with the semiconductor layer, and which has a back gate.

[0405] The crystallinity of the semiconductor layer used in the transistor 101 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 transistor characteristics.

[0406] The semiconductor layer of the transistor preferably contains silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon and single-crystal silicon). Alternatively, the semiconductor layer preferably contains metal oxide (also referred to as an oxide semiconductor). A transistor using a metal oxide in a channel formation region may be referred to as an OS transistor.

[0407] The metal oxide 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, and may be referred to as In-M-Zn oxide. In particular, M is preferably one or more elements selected from aluminum, gallium, yttrium, and tin.

[0408] As the metal oxide, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (where M is Ga, this is referred to as IGZO).

[0409] When the metal oxide 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 a composition in which In:M:Zn=1:1:1 or thereabouts, a composition in which In:M:Zn=1:1:1.2 or thereabouts, a composition in which In:M:Zn=2:1:3 or thereabouts, a composition in which In:M:Zn=3:1:2 or thereabouts, a composition in which In:M:Zn=4:2:3 or thereabouts, a composition in which In:M:Zn=4:2:4.1 or thereabouts, a composition in which In:M:Zn=5:1:3 or thereabouts, a composition in which In:M:Zn=5:1:6 or thereabouts, a composition in which In:M:Zn=5:1:7 or thereabouts, a composition in which In:M:Zn=5:1:8 or thereabouts, a composition in which In:M:Zn=6:1:6 or thereabouts, and a composition in which In:M:Zn=5:2:5 or thereabouts. The term "nearby composition" as used above refers to a range of ±30% of the desired atomic ratio.

[0410] When M=Ga, a composition having an atomic ratio of In:Ga:Zn=4:2:3 or thereabout includes a case where, when the atomic ratio of In is 4, the atomic ratio of Ga is 1 or more and 3 or less, and the atomic ratio of Zn is 2 or more and 4 or less. Furthermore, a composition having an atomic ratio of In:Ga:Zn=5:1:6 or thereabout includes a case where, when the atomic ratio of In is 5, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is 5 or more and 7 or less. Furthermore, a composition having an atomic ratio of In:Ga:Zn=1:1:1 or thereabout includes a case where, when the atomic ratio of In is 1, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is more than 0.1 and 2 or less.

[0411] A connection portion is provided in a region of the supporting substrate 411 that is exposed from the opposing substrate 443. In the connection portion, a wiring 465 is electrically connected to an FPC 472 via a conductive layer 438 and a connection layer 439. The wiring 465 can be formed using the same material as the source and drain. The conductive layer 438 can be formed using the same material as the upper electrode 159. In the connection portion, an end portion of the conductive layer 438 is covered with an insulating layer 437. The insulating layer 437 can be formed using the same material as the insulating layer 440.

[0412] The connection layer 439 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0413] Various optical members can be disposed on the outer side of the counter substrate 443. 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 also be disposed on the outer side of the counter substrate 443.

[0414] The flexibility of the display device can be increased by using a flexible material such as a plastic substrate or a thin glass substrate for the counter substrate 443. Alternatively, a polarizing plate may be used as the counter substrate 443.

[0415] Materials that can be used for the gate, source, and drain of a transistor as well as conductive layers such 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, as well as alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0416] [Display Device 400B1] Figure 32 shows a cross-sectional view of the display device 400B1. The display device 400B1 corresponds to the cross-sectional view of the display device 400A1 shown in Figure 32 when a hollow sealing structure is applied. To apply the hollow sealing structure, a substrate 500 and a counter substrate 502 are prepared. Glass substrates are preferable to plastic substrates for the substrate 500 and the counter substrate 502. A sealant 501 or the like is provided at the end to hold the counter substrate 502 in place. The space surrounded by the substrate 500, the sealant 501, and the counter substrate 502 is filled with an inert gas (such as nitrogen or argon).

[0417] The edge of the display device 400B1 shown in FIG. 32 will be described. The edge has a region 430 in addition to a region 431 similar to that of the display device 400A1 shown in FIG. 31. An opening is provided in the insulating layer 106 in the region 430. If the insulating layer 106 contains an organic material, it may become a path for moisture to penetrate, which may cause deterioration of the light-emitting device. However, providing the opening can block the path for moisture penetration. Furthermore, the opening in the insulating layer 106 in the region 430 may be filled with a layer made of the same material as the first insulator 120 and the second insulator 121. The opening in the insulating layer 106 may also be filled with the same material as the lower electrode 116 or the upper electrode 159. While such region 430 is shown as being inside the region 431, it may also be outside.

[0418] The other configurations of the display device 400B1 shown in FIG. 32 are similar to those of the display device 400A1 shown in FIG.

[0419] 33 shows a cross-sectional view of a display device 400C1. The display device 400C1 has a bottom emission structure in which light from a light-emitting device is emitted toward a support substrate 411 as indicated by the arrow, and corresponds to a cross-sectional view in which a metal oxide is used for a semiconductor layer of a transistor 101.

[0420] Since the bottom emission structure extracts light from the supporting substrate 411 side, the transistor 101 preferably contains metal oxide. This is because metal oxide has light-transmitting properties. The transistor 101 includes a back gate 420 and an insulating layer 421 covering the back gate 420. The transistor 101 also includes a source 103a and a drain 103b. The transistor 101 also includes an insulating layer 105a and an insulating layer 105b. The insulating layer 105a may contain an inorganic material, and the insulating layer 105b may contain an organic material. The source 103a and the drain 103b are formed in openings in the insulating layer 105a and the insulating layer 105b, and are electrically connected to the lower electrode 116.

[0421] In the transistor 101, the gate, source 103a, and drain 103b are located above the metal oxide. The gate, source, and drain are made of conductive materials, which can prevent light from reaching the metal oxide. Furthermore, light emitted from a light-emitting device can also be blocked.

[0422] In a display device 400C1 shown in FIG. 33, the counter substrate 443 does not have a color filter layer or a light-shielding layer.

[0423] Other configurations of the display device 400C1 shown in FIG. 33 are similar to those of the display device 400A1 shown in FIG. 31 or the display device 400B1 shown in FIG.

[0424] [Display Device 400A2] Figure 34A shows a cross-sectional view of the display device 400A2. The display device 400A2 has a display portion 462, a circuit 464, wiring 465, and the like. The display portion 462 includes a pixel region. Figure 34A shows an example in which an IC 473 and an FPC 472 are mounted on the display device 400A2. Therefore, the configuration shown in Figure 34A can also be said to be a display module including the display device 400A2, an IC (integrated circuit), and an FPC.

[0425] The display device 400A2 shown in Fig. 34A may include the light-emitting device described in the above-described embodiments 2 and 3. Other configurations of the display device 400A2 shown in Fig. 34A are similar to those of the display device 400A1 shown in Fig. 31A etc. The configurations of the transistor 101 shown in Fig. 34B etc. are similar to those of the transistor 101 shown in Fig. 31B etc.

[0426] [Display Device 400B2] Fig. 35 shows a cross-sectional view of a display device 400B2. The display device 400B2 corresponds to the cross-sectional view of the display device 400A2 shown in Fig. 34A when a hollow sealing structure is applied.

[0427] The other configurations of the display device B2 shown in FIG. 35 are similar to those of the display device 400A1 shown in FIG. 31A and the like.

[0428] 36 shows a cross-sectional view of a display device 400C2. The display device 400C2 has a bottom emission structure in which light from a light-emitting element is emitted to a supporting substrate 411 as indicated by an arrow, and corresponds to a cross-sectional view in which a metal oxide is used for a semiconductor layer of the transistor 101.

[0429] The other configurations of the display device C2 shown in FIG. 36 are similar to those of the display device 400A1 shown in FIG. 31A etc. or the display device 400B2 shown in FIG. 35 etc.

[0430] This embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification etc. For example, part of the structure shown in this embodiment mode may be implemented in appropriate combination with other embodiment modes described in this specification etc.

[0431] Embodiment 8 In this embodiment, a metal oxide (also referred to as an oxide semiconductor) that can be used for an OS transistor will be described.

[0432] 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.

[0433] 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.

[0434] <Classification of Crystal Structure> Examples of the crystal structure of metal oxides include amorphous (including completely amorphous), c-axis-aligned crystalline (CAAC), nanocrystalline (nc), cloud-aligned composite (CAC), single crystal, and polycrystalline.

[0435] The crystalline structure of the film or substrate can be evaluated using an X-ray diffraction (XRD) spectrum. For example, it can be evaluated using an XRD spectrum obtained by a GIXD (Grazing-Incident XRD) measurement. The GIXD method is also called the thin film method or the Seemann-Bohlin method.

[0436] The XRD spectrum by the GIXD method will be described. The peak shape of the XRD spectrum of a quartz glass substrate is almost symmetrical. On the other hand, the peak shape of the XRD spectrum of an IGZO film having a crystalline structure 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, it cannot be said that the film or substrate is in an amorphous state.

[0437] The crystalline structure of the film or substrate can be evaluated by a diffraction pattern (also referred to as a nanobeam electron diffraction pattern) observed by nanobeam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, and it can be confirmed that the quartz glass is in an amorphous state. Furthermore, a spot-like pattern is observed in the diffraction pattern of an IGZO film formed at room temperature, rather than a halo. For this reason, it is estimated that the IGZO film formed 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.

[0438] <<Structure of Oxide Semiconductor>> Note that oxide semiconductors may be classified differently from the above when focusing on their structure. For example, oxide semiconductors are classified 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, pseudo-amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0439] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0440] [CAAC-OS] A CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction refers to the thickness direction of the CAAC-OS film, the normal direction to the surface where the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region having periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region is also a region with a uniform lattice arrangement. Furthermore, a CAAC-OS has a region where multiple crystalline regions are connected in the a-b plane direction, and the region may have distortion. Note that distortion refers to a portion where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with another uniform lattice arrangement in a region where multiple crystalline regions are connected. In other words, a CAAC-OS is an oxide semiconductor whose c-axes are aligned and whose orientation is not clearly aligned in the a-b plane direction.

[0441] 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 a single 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 nanometers.

[0442] In an In-M-Zn oxide (wherein the element M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, and the like), 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 the element 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 the element 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.

[0443] When a CAAC-OS film is subjected to structural analysis using an XRD apparatus, for example, a peak indicating c-axis orientation is detected at or near 2θ = 31° in out-of-plane XRD measurement using θ / 2θ scanning. Note that the position of the peak indicating c-axis orientation (the value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

[0444] For example, multiple bright spots are observed in the electron diffraction pattern of a CAAC-OS film, and the observed spots are at positions that are point-symmetric with respect to a spot of an incident electron beam that has passed through the sample (also referred to as a direct spot).

[0445] When a crystalline region is observed from the specific direction, the lattice arrangement in the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be a non-regular hexagon. The distortion may have a pentagonal, heptagonal, or other lattice arrangement. In CAAC-OS, no clear grain boundary can be identified even near the distortion. This indicates that the distortion in the lattice arrangement suppresses the formation of grain boundaries. This is thought to be because CAAC-OS can tolerate distortion due to the lack of close-packed oxygen atom arrangement in the a-b plane direction and the change in interatomic bond distance caused by metal atom substitution.

[0446] Note that a crystal structure in which clear grain boundaries are observed is called polycrystalline. The grain boundaries act as recombination centers, and are likely to trap carriers, resulting in a decrease in the on-state current of a transistor and a decrease in field-effect mobility. Therefore, CAAC-OS, in which clear grain boundaries are not observed, is one of the crystalline oxides having a crystal structure suitable for a semiconductor layer of a transistor. Note that a structure containing Zn is preferable for forming a 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.

[0447] 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 the inclusion of impurity elements or the generation of defects, the CAAC-OS can also be said to be an oxide semiconductor with few impurity elements and defects (such as oxygen vacancies). Therefore, an oxide semiconductor having a CAAC-OS has stable physical properties. Therefore, an oxide semiconductor having a CAAC-OS is heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even against high temperatures (so-called thermal budget) in the manufacturing process. Therefore, using a CAAC-OS for a transistor can increase the flexibility of the manufacturing process.

[0448] [nc-OS] The nc-OS has periodic atomic arrangement in a microscopic region (for example, a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In other words, the nc-OS has microcrystals. Note that the size of the microcrystals is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore the microcrystals are also called nanocrystals. Furthermore, the nc-OS does not exhibit regularity in the crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Therefore, depending on the analysis 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 apparatus, no peak indicating crystallinity is detected in out-of-plane XRD measurement using θ / 2θ scanning. When an nc-OS film is subjected to electron diffraction (also referred to as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of a nanocrystal (e.g., 50 nm or more), a diffraction pattern resembling a halo pattern is observed. On the other hand, when an nc-OS film is subjected to electron diffraction (also referred to as nanobeam electron diffraction) using an electron beam with a probe diameter close to or smaller than that of a nanocrystal (e.g., 1 nm to 30 nm), an electron diffraction pattern in which multiple spots are observed within a ring-shaped region centered on a direct spot may be obtained.

[0449] [a-Like OS] The a-like OS is an oxide semiconductor having a structure between the nc-OS and an amorphous oxide semiconductor. The a-like OS has pores or low-density regions. 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.

[0450] <<Structure of Oxide Semiconductor>> Next, the above-described CAC-OS will be described in detail. Note that the CAC-OS relates to a material structure.

[0451] [CAC-OS] CAC-OS is a material in which, for example, elements constituting a metal oxide are unevenly distributed in a size of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or in the vicinity thereof. Note that, hereinafter, a state in which one or more metal elements are unevenly distributed in a metal oxide and regions containing the metal elements are mixed in a size of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or in the vicinity thereof, is also referred to as a mosaic or patch state.

[0452] Furthermore, the CAC-OS has a mosaic structure in which a material is separated into a first region and a second region, and the first region is distributed throughout the film (hereinafter also referred to as a cloud structure). That is, the CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0453] 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.

[0454] 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 referred to as a region whose main component is In. The second region can be referred to as a region whose main component is Ga.

[0455] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0456] Furthermore, CAC-OS in In—Ga—Zn oxide refers to a structure in which a mosaic of regions containing Ga as the main component and regions containing In as the main component are randomly arranged in a material composition containing In, Ga, Zn, and O. Therefore, it is presumed that CAC-OS has a structure in which metal elements are distributed nonuniformly.

[0457] The CAC-OS can be formed by sputtering without heating the substrate. When the CAC-OS is formed by sputtering, 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 of oxygen gas relative to the total flow rate of deposition gas during deposition, the more preferable it is. For example, the flow rate of oxygen gas relative 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.

[0458] Furthermore, for example, in the CAC-OS of an In—Ga—Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) can confirm 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.

[0459] 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).

[0460] 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.

[0461] Therefore, when a 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 (a function of turning on / off). In other words, a CAC-OS has a conductive function in a part of the material and an insulating function in a part of the material, and the entire material functions as a semiconductor. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using a CAC-OS in a transistor, a high on-current (I ｏｎ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0462] Furthermore, a transistor using the CAC-OS has high reliability, and therefore, the CAC-OS is ideal for various semiconductor devices such as display devices.

[0463] Oxide semiconductors have a variety of structures, each of which has 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.

[0464] <Transistor Having Oxide Semiconductor> Next, a case where the oxide semiconductor is used for a transistor will be described.

[0465] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0466] 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 Below 1 × 10, preferably １５ cm −３ More preferably, 1×10 １３ cm −３ Less than 1×10, more preferably 1×10 １１ cm −３ More preferably, 1×10 １０ cm −３ is less than 1×10 −９ cm −３ The above is the case. Note that in order to reduce the carrier concentration of an oxide semiconductor film, the concentration of impurity elements 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 concentration of impurity elements 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.

[0467] 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.

[0468] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to dissipate 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.

[0469] Therefore, in order to stabilize the electrical characteristics of a transistor, it is effective to reduce the concentration of impurity elements in the oxide semiconductor. Furthermore, in order to reduce the concentration of impurity elements in the oxide semiconductor, it is preferable to also reduce the concentration of impurity elements in adjacent films. Examples of impurity elements include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0470] <Impurity Elements> Here, the influence of impurity elements in an oxide semiconductor will be described.

[0471] When an oxide semiconductor contains silicon or carbon, which is one of 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 set to 2×10 １８ atoms / cm ３ Below 2 × 10, preferably １７ atoms / cm ３ The following applies.

[0472] Furthermore, when an oxide semiconductor contains an alkali metal or an alkaline earth metal, defect levels are formed and carriers are generated in some cases. Therefore, a transistor using an oxide semiconductor containing an alkali metal or an alkaline earth metal is likely to have normally-on characteristics. For this reason, when the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 １８ atoms / cm ３Below 2 × 10, preferably １６ atoms / cm ３ Do the following:

[0473] 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 5×10 １８ atoms / cm ３ Less than 1×10, more preferably 1×10 １８ atoms / cm ３ or less, more preferably 5 × 10 １７ atoms / cm ３ Do the following:

[0474] 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. Hydrogen entering the oxygen vacancy may generate electrons as carriers. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. Therefore, it is preferable to reduce hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in the oxide semiconductor measured by SIMS is 1×10 ２０ atoms / cm ３ less than 1×10 １９ atoms / cm ３ less than 5×10 １８ atoms / cm ３ less than 1×10 １８ atoms / cm ３ Make it less than.

[0475] When an oxide semiconductor in which the amount of impurity elements is sufficiently reduced is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0476] This embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification etc. For example, part of the structure shown in this embodiment mode may be implemented in appropriate combination with other embodiment modes described in this specification etc.

[0477] Embodiment 9 In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS.

[0478] 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.

[0479] 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.

[0480] 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.

[0481] In particular, the display device of one embodiment of the present invention can be suitably used in electronic devices having a relatively small display area because it can increase the resolution. 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.

[0482] 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.

[0483] 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.

[0484] 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 unit. In addition, when the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0485] The electronic device of this embodiment may have a sensor (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 rays).

[0486] 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.

[0487] The electronic device 6500 shown in FIG. 37A is a portable information terminal that can be used as a smartphone.

[0488] 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, a light source 6508, and the like. The display portion 6502 has a touch panel function.

[0489] The display device of one embodiment of the present invention can be applied to the display portion 6502 .

[0490] FIG. 37B is a cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0491] 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.

[0492] 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).

[0493] In a region outside the display portion 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.

[0494] 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.

[0495] 38A shows an example of a television set. A television set 7100 has a display portion 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0496] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0497] 38A can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, the display portion 7000 may be provided with a touch sensor, and the television set 7100 may be operated by touching the display portion 7000 with a finger or the like. The remote control 7111 may have a display portion 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 an image displayed on the display portion 7000 can be controlled.

[0498] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. Furthermore, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from a sender to a receiver) or two-way (between a sender and a receiver, or between receivers, etc.) information communication.

[0499] 38B 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. The housing 7211 includes a display portion 7000.

[0500] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0501] 38C and 38D show an example of digital signage.

[0502] 38C includes a housing 7301, a display portion 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.

[0503] 38D 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.

[0504] 38C and 38D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0505] 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.

[0506] 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, the intuitive operation can improve usability.

[0507] 38C and 38D , the digital signage 7300 or the digital signage 7400 is preferably capable of wirelessly linking 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. By operating the information terminal 7311 or the information terminal 7411, the display on the display unit 7000 can be switched.

[0508] Furthermore, the digital signage 7300 or the digital signage 7400 can be made to run 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.

[0509] FIG. 39A is a diagram showing the appearance of the camera 8000 with the viewfinder 8100 attached.

[0510] The camera 8000 includes a housing 8001, a display unit 8002, operation buttons 8003, a shutter button 8004, and the like. 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.

[0511] The camera 8000 can capture an image by pressing a shutter button 8004 or touching a display portion 8002 that functions as a touch panel.

[0512] 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.

[0513] The finder 8100 includes a housing 8101, a display portion 8102, a button 8103, and the like.

[0514] 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 portion 8102.

[0515] The button 8103 has a function as a power button or the like.

[0516] 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.

[0517] FIG. 39B is a diagram showing the appearance of the head-mounted display 8200.

[0518] 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.

[0519] 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.

[0520] The wearing unit 8201 may have 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, and may have a function of recognizing the line of sight. The wearing unit 8201 may also have a function of monitoring the user's pulse 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 have a function of displaying biometric information of the user on the display unit 8204 and a function of changing an image displayed on the display unit 8204 in accordance with the movement of the user's head.

[0521] The display device of one embodiment of the present invention can be applied to the display portion 8204 .

[0522] 39C to 39E 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.

[0523] A user can view the display on the display portion 8302 through the lens 8305. Note that it is preferable to curve the display portion 8302 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, three-dimensional display using parallax can be performed. 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 provided for each eye of the user.

[0524] 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 definition. For example, even when the display is enlarged and viewed using the lens 8305 as shown in FIG. 39E , the pixels are difficult for the user to view. That is, the display portion 8302 can be used to allow the user to view a highly realistic image.

[0525] 39F 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, an attachment 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, three-dimensional display using parallax can be performed.

[0526] 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.

[0527] The wearing section 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 portion of the wearing section 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 for outputting audio data via wireless communication.

[0528] The mounting portion 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 a material is preferable because it feels pleasant to the touch and prevents the user from feeling cold when worn in cold seasons. It is preferable that the buffer member 8403 or the mounting portion 8402, or other components that come into contact with the user's skin, are removable for easy cleaning or replacement.

[0529] The electronic device shown in Figures 40A to 40F 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, speed, 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 rays), a microphone 9008, etc.

[0530] The electronic devices shown in Figures 40A to 40F 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 devices are not limited to these, and they may have various other functions. The electronic devices may have multiple display units. Furthermore, the electronic devices 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.

[0531] The display device of one embodiment of the present invention can be applied to the display portion 9001 .

[0532] The electronic devices shown in Figures 40A to 40F will be described in detail below.

[0533] FIG. 40A 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. FIG. 40A 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, an icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0534] 40B is a perspective view showing the mobile information terminal 9102. The mobile information terminal 9102 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9102 while storing the mobile information terminal 9102 in a breast pocket of clothes. The user can check the display without taking the mobile information terminal 9102 out of the pocket and decide, for example, whether to answer a call.

[0535] FIG. 40C 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 display can be performed along the curved display surface. Hands-free calling is also possible by intercommunicating the mobile information terminal 9200 with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and charging with another information terminal through a connection terminal 9006. Charging may be performed by wireless power supply.

[0536] 40D to 40F are perspective views showing a foldable mobile information terminal 9201. Also, FIG. 40D is a perspective view of the mobile information terminal 9201 in an unfolded state, FIG. 40F is a perspective view of the mobile information terminal 9201 in a folded state, and FIG. 40E is a perspective view of a state in the process of changing from one of FIG. 40D and FIG. 40F to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent visibility of the display. The display portion 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display portion 9001 can be bent with a curvature radius of 0.1 mm or more and 150 mm or less.

[0537] This embodiment mode can be implemented in appropriate combination with other embodiment modes described in this specification etc. For example, part of the structure shown in this embodiment mode may be implemented in appropriate combination with other embodiment modes described in this specification etc.

[0538] AL: wiring, CL: wiring, GL: wiring, SL: wiring, 10: pixel region, 11B: pixel, 11G: pixel, 11R: pixel, 15B: contact hole, 15G: contact hole, 15R: contact hole, 18: contact hole, 20: light-emitting device, 100: substrate, 101a: transistor, 101: transistor, 102: gate, 103a: source, 103b: drain, 103: drain, 105a: insulating layer, 105b: insulating layer, 105: insulating layer, 106: insulating layer, 107: insulating layer, 110x: first region, 110y: second region, 110: separator Wall, 114: conductive layer, 115: auxiliary electrode, 116: lower electrode, 117: conductive layer, 119B: inkjet nozzle, 119G: inkjet nozzle, 119R: inkjet nozzle, 120: first insulator, 121: second insulator, 150: layer, 153B: light-emitting layer, 153G: light-emitting layer, 153R: light-emitting layer, 155: layer, 159: upper electrode, 160: layer, 161: metal mask, 163B: light-emitting layer, 163G: light-emitting layer, 163R: light-emitting layer, 165: layer, 216: upper electrode, 259: lower electrode, 311i: channel formation region, 311n: low-resistance region, 31 1: semiconductor layer, 312: insulating layer, 313: conductive layer, 314a: conductive layer, 314b: conductive layer, 315: conductive layer, 316: insulating layer, 321: insulating layer, 322: insulating layer, 323: insulating layer, 326: insulating layer, 350a: transistor, 350: transistor, 351: semiconductor layer, 352: insulating layer, 353: conductive layer, 354a: conductive layer, 354b: conductive layer, 355: conductive layer, 411: supporting substrate, 412: adhesive layer, 413: resin layer, 415: insulating layer, 416: insulating layer, 420: back gate, 421: insulating layer, 430: region, 431: region, 432: conductive layer, 434: Light-shielding layer, 435: conductive layer, 437: insulating layer, 438: conductive layer, 439: connection layer, 440: insulating layer, 442: adhesive layer, 443: opposing substrate, 444B: color filter layer, 444G: color filter layer, 444R: color filter layer, 462: display section, 464: circuit, 465: wiring, 472: FPC, 473: IC, 500: substrate, 501: sealing material, 502: opposing substrate, 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: light-emitting layer, 4412: first light-emitting layer, 4413: second light-emitting layer, 4414: 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 device, 7400: Digital signage, 7401: Pillar, 7411: Information terminal device, 8000: Camera, 8001: Housing Body, 8002: display unit, 8003: operation buttons, 8004: shutter button, 8006: lens, 8100: viewfinder, 8101: housing, 8102: display unit, 8103: button, 8200: head-mounted display, 8201: attachment unit, 8202: lens, 8203: body, 8204: display unit, 8205: cable, 8206: battery, 8300: head-mounted display, 8301: housing, 8302: display unit, 8304: fixture, 8305: lens, 8400: head-mounted display front display, 8401: housing, 8402: mounting part, 8403: cushioning member, 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: portable information terminal, 9102: portable information terminal, 9200: portable information terminal, 9201: portable information terminal,

Claims

1. A first bottom electrode; a second lower electrode located in a region adjacent to the first lower electrode in the X direction when viewed from above; a third lower electrode located in a region adjacent to the first lower electrode in a Y direction when viewed from above; an auxiliary electrode located at least between the first lower electrode and the second lower electrode when viewed from above; a partition wall having an area overlapping an end portion of the first lower electrode, an end portion of the second lower electrode, an end portion of the third lower electrode, and the auxiliary electrode; a first light-emitting layer having a region overlapping the first lower electrode and positioned in the opening of the partition wall; a first layer located between the first lower electrode and the first light-emitting layer; a second light-emitting layer having a region overlapping with the second lower electrode and positioned in the opening of the partition; a second layer located between the second lower electrode and the second light-emitting layer; a third light-emitting layer having a region overlapping with the third lower electrode and positioned in the opening of the partition; a third layer located between the third lower electrode and the third light-emitting layer; an upper electrode provided across the first light-emitting layer to the third light-emitting layer; the upper electrode is electrically connected to the auxiliary electrode through a contact hole located at least between the first lower electrode and the second lower electrode; each of the first layer to the third layer has a hole transport layer or a hole injection layer; the partition has a laminated structure of a first insulator having an inorganic material and a second insulator having an organic material, the contact hole has a first opening in the first insulator and a second opening in the second insulator; When viewed from above, the first insulator has an end portion exposed from the second opening portion; the upper electrode is electrically connected to the auxiliary electrode via the conductive layer exposed from the first opening.

2. In claim 1, A display device, wherein a height of the partition wall along the X direction is smaller than a height of the partition wall along the Y direction.

3. In claim 1 or 2, The display device, wherein an intersection between the partition wall along the X direction and the partition wall along the Y direction is the highest.