Display device

Abstract

To provide a foldable display device with excellent portability.SOLUTION: A display device includes a flexible display panel and can be folded into a smaller size. The display device has a three-fold mechanism, and can form a region in which a first surface of the display device is folded so that the folded parts face each other, and a region in which a second surface, which is opposite to the first surface, of the display device is folded so that the folded parts face each other. Therefore, even a display panel with a relatively large aspect ratio can be folded into a small size by having a joint in a minor-axis direction, and the portability can be improved.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an object, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, a manufacture, or a composition of matter. In particular, one aspect of the present invention relates to a semiconductor device, a light-emitting device, a display device, an electronic device, a lighting device, a driving method thereof, or a manufacturing method thereof. In particular, the present invention relates to a display device having a flexible display surface, and a method for operating or manufacturing the same.

[0002] In this specification and the like, a semiconductor device refers to any device that can function by utilizing semiconductor characteristics. A transistor, a semiconductor circuit, an arithmetic device, a memory device, and the like are examples of a semiconductor device. A light-emitting device, a display device, a lighting device, and an electronic device may include a semiconductor device. [Background technology]

[0003] Electronic devices such as mobile phones, smartphones, tablet computers, and laptop computers are made to an appropriate size according to their functions, ease of use, and portability. On the other hand, it is inconvenient to carry multiple electronic devices. Therefore, a form that can integrate the functions of multiple electronic devices is desired. For example, Patent Document 1 discloses a tri-fold type light-emitting panel. By using this light-emitting panel, it is possible to integrate the functions of multiple electronic devices and create an electronic device with a variable size. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-130320 A Summary of the Invention [Problem to be solved by the invention]

[0005] One object of one embodiment of the present invention is to provide a foldable display device with excellent portability. Another object is to provide a foldable display device with excellent display visibility. Another object is to provide a foldable display device with a power-saving function. Another object is to provide a foldable display device that is easy to hold. Another object is to provide a novel display device. Another object is to provide an operation method of the novel display device.

[0006] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily solve all of these problems. In addition, problems other than those described above will become apparent from the description of the specification, etc., and problems other than those described above can be extracted from the description of the specification, etc. [Means for solving the problem]

[0007] One embodiment of the present invention relates to a tri-fold foldable display device that is highly portable.

[0008] One embodiment of the present invention is a display device having a flexible display panel having a first region, a second region, and a third region, and when laid out flat, the first region, the second region, and the third region are parallel to each other to form a surface, and the second region is provided between the first region and the third region and has a function of forming a first curved surface extending from the first region to the second region with the display surface side being convex, and a function of forming a second curved surface extending from the second region to the third region with the display surface side being concave, and when folded, the radius of curvature R1 of the first curved surface is greater than the radius of curvature R2 of the second curved surface.

[0009] Another aspect of the present invention is a display device having a flexible display panel having a first region, a second region, and a third region, and when unfolded flat, the first region, the second region, and the third region are parallel to each other to form a surface, and the second region is provided between the first region and the third region, and has a function of continuously forming, in that order, a first curved surface with a convex display surface side, a flat surface, and a third curved surface with a convex display surface side, from the first region to the second region, and a function of forming a second curved surface with a concave display surface side from the second region to the third region, and when folded, the radius of curvature R1 of the first curved surface is larger than the radius of curvature R2 of the second curved surface, and the radius of curvature R3 of the third curved surface is larger than the radius of curvature R2, and the radius of curvature R1 is approximately equal to the radius of curvature R3.

[0010] In the above two aspects, the device may further include a first housing, a second housing, a third housing, a first hinge, and a second hinge, at least a portion of the first region is fixed to the first housing, at least a portion of the second region is fixed to the second housing, and at least a portion of the third region is fixed to the third housing, a first hinge is provided between the first housing and the second housing, and a second hinge is provided between the second housing and the third housing, the first hinge has a function of forming a first curved surface, and the second hinge has a function of forming a second curved surface, and when deployed flat, the overall center of gravity may be within the first housing or the third housing.

[0011] A battery may be provided within the first housing or the third housing.

[0012] A receiving coil for wireless charging may be provided inside the third housing.

[0013] The display panel preferably comprises a light emitting device.

[0014] Another embodiment of the present invention is a method for operating a display device that performs display only in a part of its area when the display panel is folded. Furthermore, when the display panel is opened flat, the display device may perform an operation of changing the orientation of an image in response to the inclination of the display panel. Effect of the Invention

[0015] By using one embodiment of the present invention, a foldable display device with excellent portability can be provided. Alternatively, a foldable display device with excellent display visibility can be provided. Alternatively, a foldable display device having a power-saving function can be provided. Alternatively, a foldable display device with excellent ease of holding can be provided. Alternatively, a novel display device can be provided. Alternatively, a method for operating a novel display device can be provided.

[0016] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract effects other than these from the description in the specification, drawings, claims, etc. [Brief description of the drawings]

[0017] [Figure 1] 1A and 1B are diagrams illustrating a display device. [Diagram 2] 2A to 2C are diagrams illustrating a display device. [Diagram 3] 3A and 3B are diagrams illustrating a display device. [Figure 4] 4A to 4C are diagrams illustrating a hinge. [Diagram 5] 5A to 5C are diagrams illustrating a hinge. [Figure 6] 6A to 6C are diagrams illustrating a hinge. [Figure 7] 7A to 7C are diagrams illustrating a hinge. [Figure 8]8A to 8D are diagrams illustrating a display device. [Figure 9] 9A and 9B are diagrams illustrating the operation of the display device. [Figure 10] FIG. 10 is a flowchart illustrating the operation of the display device. [Figure 11] Fig. 11A is a circuit diagram of a protection circuit, and Fig. 11B is a block diagram illustrating a connection form of the protection circuit. [Figure 12] Fig. 12A is a diagram illustrating a display device, and Fig. 12B is a diagram illustrating wireless charging of the display device. [Figure 13] 13A to 13C are diagrams illustrating the operation of the display device. [Figure 14] 14A to 14C are diagrams illustrating the operation of the display device. [Figure 15] 15A to 15C are diagrams illustrating the operation of the display device. [Figure 16] 16A and 16B are diagrams for explaining application examples of the display device. [Figure 17] 17A to 17D are diagrams for explaining application examples of the display device. [Figure 18] 18A and 18B are diagrams for explaining application examples of the display device. [Figure 19] FIG. 19 is a block diagram illustrating an example of a television device. [Figure 20] FIG. 20 is a diagram illustrating an example of the configuration of a display panel. [Figure 21] FIG. 21 is a diagram illustrating an example of the configuration of a display panel. [Figure 22] FIG. 22 is a diagram illustrating an example of the configuration of a display panel. [Figure 23] Fig. 23A is a block diagram of a display panel, and Fig. 23B and Fig. 23C are circuit diagrams of a pixel. [Figure 24] Figures 24A, 24C and 24D are circuit diagrams of the pixel, and Figure 24B is a timing chart illustrating the operation of the pixel. [Diagram 25]25A to 25E are diagrams for explaining examples of pixel configurations. [Figure 26] Fig. 26A is a diagram explaining the classification of IGZO crystal structures. Fig. 26B is a diagram explaining the XRD spectrum of quartz glass. Fig. 26C is a diagram explaining the XRD spectrum of crystalline IGZO. Fig. 26D is a diagram explaining the ultrafine electron beam diffraction pattern of crystalline IGZO. [Figure 27] 27A-27D are cross-sectional views of a light emitting device. [Figure 28] 28A to 28C are conceptual diagrams for explaining a light emission model of a light emitting device, and Fig. 28D is a diagram for explaining normalized luminance of a light emitting device over time. [Figure 29] 29A to 29D are diagrams illustrating the concentration of an organometallic complex in the electron transport layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 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 is easily understood by those skilled in the art that the form and details of the present invention can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention is not interpreted as being limited to the description of the embodiments shown below. In the configuration of the invention described below, the same reference numerals are used in common between different drawings for the same parts or parts having similar functions, and repeated explanations may be omitted. In addition, hatching of the same elements constituting the drawings may be omitted or changed as appropriate between different drawings.

[0019] In addition, even if a circuit diagram shows a single element, the element may be configured as a plurality of elements as long as there is no functional problem. For example, a plurality of transistors operating as a switch may be connected in series or parallel. A capacitor may also be divided and placed in multiple positions.

[0020] In addition, one conductor may have multiple functions such as wiring, an electrode, and a terminal, and in this specification, multiple names may be used for the same element. Even if elements are shown as being directly connected to each other on a circuit diagram, the elements may actually be connected to each other via one or more conductors, and in this specification, such a configuration is also included in the category of direct connection.

[0021] (Embodiment 1) In this embodiment, a display device according to one embodiment of the present invention will be described with reference to the drawings. Note that in this specification, a display device refers to any device having a display function. In other words, electronic devices having a display portion are included in the display device. For example, electronic devices having a display portion, such as mobile phones, smartphones, smart watches, tablet computers, and television sets, are included in the display device.

[0022] One embodiment of the present invention is a display device that has a flexible display panel and can be folded into a small size. The display device has a tri-folding mechanism, and can form a region where the display device is folded so that first surfaces of the display device face each other, and a region where the display device is folded so that second surfaces opposite the first surfaces face each other. Therefore, even a display panel with a relatively large aspect ratio, such as 16:9, 18:9, or 21:9, can be folded into a small size by providing a fold in the minor axis direction, and portability can be improved. In addition, when folded into a small size, a display region that cannot be seen is hidden, and power consumption can be significantly reduced.

[0023] <Display device> FIG. 1A is a diagram showing a state in which a display device 100A of one embodiment of the present invention is folded to a minimum size. The display device 100A can be deformed as shown in FIGS. 2A to 2C. When the display device 100A is initially in a folded state (see FIG. 2A), it can be changed to a deformed state (see FIG. 2B) and then to a flat, unfolded state (see FIG. 2C). It can be folded by deforming it in the reverse order. Note that the display device 100A can be deformed manually, or may be deformed using electrical power or mechanical power such as a spring.

[0024] The display device 100A has a flexible display panel 101, a housing 102a, a housing 102b, a housing 102c, and a hinge 103a and a hinge 103b. In this embodiment, for the sake of clarity, the display panel 101 is divided into three regions, a region 101a, a region 101b, and a region 101c (see FIG. 2C). The regions 101a, 101b, and 101c are regions that are parallel to the horizontal direction (the direction in which the surface of the display panel 101 extends) and form a surface when the display panel 101 is flatly developed, and are regions that are bounded by a position where a hinge is provided or the vicinity thereof. In reality, there is no structural difference between the regions 101a to 101c and their boundaries. A seamless, flexible display panel can be used for the display panel 101.

[0025] Fig. 1B is a cross-sectional view taken along the line A1-A2 of Fig. 1A. Housing 102a is connected to housing 102b via hinge 103a. Housing 102b is connected to housing 102c via hinge 103b.

[0026] The display panel 101 is provided on the first surface side of the housings 102a to 102c. At least a part of the region 101a can be fixed to the housing 102a. At least a part of the region 101b can be fixed to the housing 102b. At least a part of the region 101c can be fixed to the housing 102c.

[0027] If the surface of the display panel 101 fixed to the housing is defined as a non-display surface, and the surface of the display panel 101 opposite to the surface fixed to the housing is defined as a display surface, as shown in FIG. 1A and FIG. 1B, when folded, the non-display surfaces of the regions 101a and 101b face each other, and a curved surface 104a is formed from the region 101a to the region 101b, with the display surface being convex. The curved surface 104a is defined as a region formed by a part of the region 101a and a part of the region 101b. The display surfaces of the regions 101b and 101c face each other, and a curved surface 104b is formed from the region 101b to the region 101c, with the display surface being concave. The curved surface 104b is defined as a region formed by a part of the region 101b and a part of the region 101c.

[0028] The distance from the surface (display surface) of the curved surface to the center of curvature is defined as the radius of curvature, and the radius of curvature of curved surface 104a when display panel 101 is folded to its minimum size is defined as R1, and the radius of curvature of curved surface 104b is defined as R2. In this case, it is preferable that R1>R2.

[0029] R1 is the radius of curvature when the display surface is bent outward, and even if the thickness of the housings 102a, 102a is formed to be thin within an appropriate range, it will be a relatively large value, and the stress applied to the portion forming the curved surface 104a of the display panel 101 will be small. On the other hand, R2 is the radius of curvature when the display surface is bent inward, and regardless of the thickness of the housings 102b, 102c, it will be a relatively small value, and the stress applied to the portion forming the curved surface 104b of the display panel 101 will tend to be large.

[0030] Therefore, by making R2 the same as or greater than R1, the stress applied to the curved surface 104b can be reduced and reliability can be improved. On the other hand, if R2 is made larger, the overall thickness when folded increases, which reduces portability.

[0031] In one embodiment of the present invention, a display panel that is resistant to bending stress is used, so that R1>R2 can be realized without impairing reliability. A display panel that is resistant to bending stress can be realized by using a transistor having a metal oxide (oxide semiconductor) in a channel formation region (hereinafter, referred to as an OS transistor) in a pixel circuit.

[0032] Metal oxides can be formed by a film formation method such as sputtering, and can be created through a relatively low-temperature process. Therefore, they have little residual stress on devices such as transistors and surrounding components such as protective films, and are highly resistant to bending stress applied later.

[0033] On the other hand, transistors with electrical characteristics at the same level as OS transistors include transistors that have silicon (low-temperature polysilicon, single crystal silicon, etc.) in the channel formation region (hereafter, Si transistors). The manufacturing process for low-temperature polysilicon transistors involves a silicon film laser crystallization process. In the laser crystallization process, the silicon film is heated to a high temperature (at least the melting point of silicon) for a short period of time, and then rapidly cooled. As a result, there is a lot of residual stress in the silicon film and surrounding components, and if further bending stress is added later, the electrical characteristics and other aspects of the film deteriorate, reducing reliability.

[0034] Therefore, in the display device according to one embodiment of the present invention, it is easy to make R1>R2, and the display device can be folded small without losing reliability. Note that since bending resistance differs depending on the radius of curvature, the number of times of bending, etc., Si transistors may be used in the pixel circuits depending on the situation.

[0035] As a semiconductor material used for an OS transistor, a metal oxide having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more can be used. A typical example is an oxide semiconductor containing indium, for example, CAAC-OS or CAC-OS described later can be used. CAAC-OS has stable atoms constituting the crystal, and is suitable for transistors that emphasize reliability. In addition, CAC-OS has high mobility characteristics, and is suitable for transistors that operate at high speed.

[0036] Because the energy gap of the semiconductor layer is large, OS transistors can exhibit extremely low off-current characteristics of several yA / μm (current value per 1 μm of channel width). OS transistors also have characteristics different from Si transistors, such as the absence of impact ionization, avalanche breakdown, and short channel effects, making it possible to form highly reliable circuits. Furthermore, OS transistors are less susceptible to variations in electrical characteristics caused by non-uniformity in crystallinity, which is a problem with Si transistors.

[0037] The semiconductor layer of the OS transistor can be, for example, a film represented by In-M-Zn oxide containing indium, zinc, and M (metal such as aluminum, titanium, gallium, germanium, yttrium, zirconium, lanthanum, cerium, tin, neodymium, or hafnium). The semiconductor layer of the OS transistor can be made of In oxide, In-Ga oxide, or In-Zn oxide in addition to the above-mentioned In-M-Zn oxide. Note that the on-current or field effect mobility of the OS transistor can be increased by using a semiconductor layer having a composition with a high ratio of indium. The In-M-Zn oxide can be formed by, for example, a sputtering method, an atomic layer deposition (ALD) method, or a metal organic chemical vapor deposition (MOCVD) method.

[0038] When forming a film of In-M-Zn oxide by a sputtering method, the atomic ratio of the metal elements of the sputtering target preferably satisfies In≧M and Zn≧M. As the atomic ratio of the metal elements of such a sputtering target, In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn=3:1:2, In:M:Zn=4:2:3, In:M:Zn=4:2:4.1, In:M:Zn=5:1:3, In:M:Zn=5:1:6, In:M:Zn=5:1:7, In:M:Zn=5:1:8, In:M:Zn=10:1:3, etc. are preferable. In addition, when the oxide semiconductor constituting the semiconductor layer is In-Zn oxide, the atomic ratio of the metal elements of the sputtering target used to form the In-Zn oxide film preferably satisfies In≧Zn. The atomic ratio of the metal elements in such a sputtering target is preferably In:Zn=1:1, In:Zn=2:1, In:Zn=5:1, In:Zn=5:3, In:Zn=10:1, In:Zn=10:3, etc.

[0039] The semiconductor layer is made of an oxide semiconductor with a low carrier concentration. For example, the semiconductor layer has a carrier concentration of 1×10 17 / cm 3 Less than or equal to 1×10 15 / cm 3 Less than 1×10, more preferably 13 / cm 3 Less than or equal to 1×10 11 / cm 3 Less than 1×10, more preferably 10 / cm 3 Less than 1 x 10 -9 / cm 3 An oxide semiconductor having a carrier concentration of 1000 to 1500 nm can be used. Such an oxide semiconductor is called a high-purity intrinsic or substantially high-purity intrinsic oxide semiconductor. The oxide semiconductor has a low density of defect states and stable characteristics.

[0040] Note that the composition is not limited to these, and an appropriate composition may be used depending on the required semiconductor characteristics and electrical characteristics (field-effect mobility, threshold voltage, etc.) of the transistor. In order to obtain the required semiconductor characteristics of the transistor, it is preferable to appropriately set the carrier concentration, impurity concentration, defect density, atomic ratio of metal element to oxygen, interatomic distance, density, and the like of the semiconductor layer.

[0041] The hinges 103a and 103b are illustrated in an abstract manner, and their shapes are not important. Specific examples of the hinges 103a and 103b will be described later, but they may be made of an elastic body such as rubber, connected pillars, or gears. Although the housing and the hinges are shown as separate elements in FIG. 1A and FIG. 1B, the boundary between them may not be clear, and the housing and the hinges may be integrated. Also, the display panel 101 may not be in contact with the hinges.

[0042] <Display Device Variation 1> Another embodiment of the present invention may have a structure shown in Fig. 3A. A display device 100B shown in Fig. 3A has a structure in which the hinge 103a of the display device 100A is replaced with a hinge 103c.

[0043] Hinge 103c of display device 100B has a function of forming, when folded, curved surface 105a with a convex display surface, flat surface 105, and curved surface 105b with a convex display surface, in that order, from region 101a to region 101b. Note that curved surface 105a is an area formed by a part of region 101a, flat surface 105 is an area formed by a part of region 101a and a part of region 101b, and curved surface 105b is an area formed by a part of region 101c.

[0044] As shown in the cross-sectional view of FIG. 3B, when the radius of curvature of the curved surface 105a when folded to the minimum size is R3, and the radius of curvature of the curved surface 105b is R4, it is preferable that R3>R2 and R4>R2. By making R3>R2 and R4>R2, the overall thickness can be reduced as in the display device 100A. It is also preferable that R3 and R4 are equal or approximately equal. By making R3 and R4 equal, the display device can be folded symmetrically, and the reliability of the hinge mechanism can be improved. If R3 and R4 are significantly different, one of the area where the curved surface 105a is formed or the area where the curved surface 105b is formed may be more easily bent than the other when folded or unfolded, which may impair reliability.

[0045] 3A and 3B, when the display device 100B is folded, a plane 105 is formed by the hinge 103c. Therefore, the proportion of the plane in the folded portion increases, and the visibility of the image can be improved.

[0046] <Hinge> 4A to 4C are diagrams illustrating an example of a hinge 103a that can be used in the display device 100A shown in FIG. 1A.

[0047] Hinge 103a has a plurality of pillars 111 whose cross section in the short axis direction is trapezoidal or approximately trapezoidal. Each pillar 111 is connected so that its bottom surface (corresponding to the lower base of the trapezoid) is continuous. The bottom surface of pillar 111 at one end of hinge 103a is connected so as to be continuous with the first surface of housing 102a. The bottom surface of pillar 111 at the other end of hinge 103a is connected so as to be continuous with the first surface of housing 102b. The shape of the top surface (corresponding to the upper base of the trapezoid) of each pillar 111 can be any shape as long as it does not interfere with other pillars and housings.

[0048] As shown in Fig. 4A, the columnar structure 111 can be folded by deforming the columnar structure 111 so that the side surfaces (corresponding to the legs of the trapezoid) of adjacent columns 111 come into contact with each other. At this time, the bottom surfaces of the columns 111 are joined at a certain angle, forming an area whose cross section is generally arc-shaped as a whole. Therefore, the flexible display panel can form a curved surface in the area that overlaps with this area.

[0049] When a deformation operation (unfolding operation) is performed from the state of Fig. 4A, the side surfaces of the respective pillars 111 move in the direction away from each other, and the radius of curvature of the approximately circular arc described above changes to become larger, as shown in Fig. 4B. At this time, the radius of curvature of the curved portion of the display panel also changes to become larger.

[0050] When the deformation operation is further performed from the state shown in FIG. 4B, the first surface of the housing 102a, the bottom surfaces of the respective pillars 111, and the first surface of the housing 102b are connected so as to be flat, as shown in FIG. 4C. At this time, the curved portions of the display panel also become flat, and the whole is in a flat, unfolded state. If the deformation operation is performed in the reverse order to the above, the device can be folded.

[0051] In the above, the cross section of the pillar 111 is trapezoidal, but it may be triangular. The configuration for connecting each pillar and the housing is not limited. A stopper may be provided to prevent bending in the opposite direction to the intended direction. A spacer may be provided to maintain a gap between the housings when folded. The housing or the hinge may be appropriately changed to a shape suitable for installation of the display panel. These can also be applied to the hinge 103c described next.

[0052] 5A to 5C are diagrams illustrating an example of a hinge 103c that can be used in the display device 100B shown in FIG. 3A.

[0053] Hinge 103c has units 113a and 113b having elements roughly equivalent to hinge 103a. Note that units 113a and 113b may have a different number of pillars from hinge 103a. In addition, between units 113a and 113b, there is a pillar 114 having a flat bottom surface and a side surface perpendicular to the bottom surface. The shape of the top surface of pillar 114 is arbitrary as long as it does not interfere with other pillars or the housing.

[0054] As shown in Fig. 5A, the unit 113a can be folded by deforming the unit 113a so that the side surfaces of the pillars 114 and 113b are in contact with each other. At this time, the bottom surfaces of the pillars of the unit 113a are connected at a certain angle, forming a region whose cross section is approximately arc-shaped. The same is true for the unit 113b. Therefore, the flexible display panel can form a curved surface, a flat surface, and a curved surface in the portion overlapping with the region.

[0055] The pillars in unit 113a, pillar 114, and pillars in unit 113b are connected so that their bottom surfaces are continuous. The bottom surface of the pillar at one end of unit 113a is connected so that it is continuous with the first surface of housing 102a. The bottom surface of the pillar at one end of unit 113b is connected so that it is continuous with the first surface of housing 102b.

[0056] When a deformation operation (unfolding operation) is performed from the state of Fig. 5A, the side surfaces of the respective pillars of units 113a and 113b move in the direction away from each other, and the radius of curvature of the approximately circular arc described above changes to become larger, as shown in Fig. 5B. At this time, the radius of curvature of the curved portion of the display panel also changes to become larger.

[0057] When the deformation operation is further performed from the state of Fig. 5B, as shown in Fig. 5C, the first surface of the housing 102a, the bottom surface of the pillar of the unit 113a, the bottom surface of the pillar 114, the bottom surface of the pillar of the unit 113b, and the first surface of the housing 102b are connected so as to be flat. At this time, the curved portion of the display panel also changes to a flat surface, and the whole is in a flat unfolded state. If the deformation operation is performed in the reverse order to the above, it can be folded.

[0058] 6A to 6C are diagrams illustrating an example of a hinge 103b that can be used in the display device 100A shown in FIG. 1A or the display device 100B shown in FIG. 3A.

[0059] Hinge 103b has a plurality of pillars 115 with a rectangular cross section in the short axis direction. Each pillar 115 is connected so that its bottom surface is continuous. The bottom surface of pillar 115 at one end of hinge 103b is connected so as to be continuous with the first surface of housing 102a. The bottom surface of pillar 115 at the other end of hinge 103b is connected so as to be continuous with the first surface of housing 102c. The shape of the top surface of each pillar 115 may be any shape as long as it does not interfere with other pillars and the housing.

[0060] As shown in Fig. 6A, the side surfaces of adjacent columns 115 are deformed in a direction away from each other to be folded. At this time, the bottom surfaces of multiple columns 115 are joined at a certain angle, forming an area whose cross section is generally arc-shaped as a whole. Therefore, the flexible display panel can form a curved surface in the area that overlaps with this area.

[0061] When a deformation operation (unfolding operation) is performed from the state of Fig. 6A, the side faces of the respective pillars 115 move closer to each other, and the radius of curvature of the approximately circular arc described above changes to become larger, as shown in Fig. 6B. At this time, the radius of curvature of the curved portion of the display panel also changes to become larger.

[0062] When the deformation operation is further performed from the state shown in FIG. 6B, the first surface of the housing 102b, the bottom surfaces of the respective pillars 115, and the first surface of the housing 102c are connected so as to be flat, as shown in FIG. 6C. At this time, the curved surface portion of the display panel also becomes flat, and the whole is in a flat, unfolded state. If the deformation operation is performed in the reverse order to the above, the device can be folded.

[0063] Since the cross section of the pillars 115 is rectangular, the sides of the pillars 115 come into contact with each other when the pillars 115 are unfolded flat. Therefore, the hinges 103b do not cause the display panel to bend in the opposite direction, making it possible to eliminate the need for a stopper. A spacer may be provided to maintain a gap between the housings when folded. The housings or the hinges may be appropriately deformed into a shape suitable for installation of the display panel.

[0064] 7A to 7C are diagrams illustrating another example of the hinge 103b.

[0065] Hinge 103b has gears 116a and 116b. Gear 116a is fixed to housing 102a. Gear 116b is fixed to housing 102b. The central axis of gear 116a preferably overlaps with the first surface of housing 102a. In addition, the central axis of gear 116b preferably overlaps with the first surface of housing 102b.

[0066] As shown in Fig. 7A, the gears 116a and 116b are meshed at a specific position when the display device is folded. At this time, the central axes of the two gears are on the first surface of the housing, so a gap is generated between the housings (between the opposing display surfaces of the display panels). Therefore, the flexible display panel can form a curved surface with a radius of curvature that is approximately half of the gap.

[0067] When a transformation (unfolding) operation is performed from the state of Fig. 7A, housings 102b and 102c synchronize in response to the meshing of gears 116a and 116b, and move to open around hinge 103b as a fulcrum (see Fig. 7B). At this time, the display panel also changes so that the radius of curvature of the curved surface portion increases.

[0068] When the deformation operation is further performed from the state shown in FIG. 7B, the first surface of the housing 102b and the first surface of the housing 102c are connected so as to become flat, as shown in FIG. 7C. At this time, the curved portion of the display panel also becomes flat, and the whole is in a flat, unfolded state. If the deformation operation is performed in the reverse order to the above, the device can be folded.

[0069] A mechanism for maintaining the meshing of the gears 116a and 116b may be provided. When the device is unfolded flat, the side of the housing 102c comes into contact with the side of the housing 102c. Therefore, the hinge 103b does not cause the display panel to bend in the opposite direction, and a stopper is not required. A spacer may be provided to maintain the gap between the housings when the device is folded. Alternatively, a mechanism for maintaining the gap may be provided on the gears 116a and 116b. The housing or the hinge may be appropriately deformed into a shape suitable for the installation of the display panel.

[0070] <Modification 2 of the display device> 8A is a diagram illustrating a display device 100C which is a modification of the display device 100A. The display device 100C differs from the display device 100A in the shape of the housing 102c.

[0071] The housing 102c of the display device 100C is formed thicker than the housings 102a and 102b. As shown in FIG. 8B, by forming the housing 102c thick, a relatively large battery 117 can be housed therein, and the display device can operate for a long time. In addition, by housing the relatively heavy battery 117 inside the housing 102c, the center of gravity of the display device 100C can be located inside the housing 102c not only in the state of FIG. 8A but also in the state of FIG. 8B. Since the housing 102c is thick and the center of gravity is inside the housing 102c, the ease of holding the display device can be improved when the display device is unfolded flat.

[0072] In addition, the display device 100C is configured to be easy to operate regardless of the user's dominant hand. Fig. 9A is a diagram showing a case where the housing 102c side of the display device 100C is held in the left hand and the screen is touched with the right hand. Fig. 9B is a diagram showing a case where the housing 102c side of the display device 100C is held in the right hand and the screen is touched with the left hand. In either case, the image can be displayed in an orientation that is easy for the user to view.

[0073] This operation is performed by detecting the inclination of the display device 100C with a sensor 120 (such as an acceleration sensor or a gyro sensor) included in the display device 100C and determining the display orientation of the image from the inclination. The sensor 120 can also detect the shaking of the display device 100C from a change in the inclination. Since the shaking varies from person to person, the user can be identified by having artificial intelligence (AI) learn the shaking information. This function can also be used to perform personal authentication. The sensor 120 can also be provided in other display devices shown in this embodiment.

[0074] FIG. 10 is a flow chart for determining the orientation of a displayed image using the sensor 120 and for performing personal authentication.

[0075] The path from S1 through S2 is an operation for determining the display orientation of an image using the tilt detection result by the sensor. Note that there are multiple directions of tilt, and tilt A, tilt B, and tilt C include tilt conditions for multiple directions. Here, tilt A is the range including the tilt of the display device 100C shown in FIG. 9A, tilt C is the range including the tilt of the display device 100C shown in FIG. 9B, and tilt B is the range including the tilt when the long axis direction of the display device 100C is the up-down direction. Note that there are two ways in which tilt B is up-down reversed, so in reality, a determination may be made for four tilt ranges.

[0076] If the inclination is determined to be A, A display is performed. A display is a mode in which an image is displayed in the orientation shown in FIG. 9A. If the inclination is determined to be C, C display is performed. C display is a mode in which an image is displayed in the orientation shown in FIG. 9B. If the inclination is determined to be B, B display is performed. B display is, for example, a mode in which the image of display device 100C shown in FIG. 9A is rotated approximately 90 degrees and displayed. In this way, by utilizing sensor 120, the orientation of the image can be changed to make it easier to view.

[0077] The routes S1, S3, and S4 are operations for accumulating data on the vibrations detected by the sensor 120 and registering the data and the individual. The data registered here is used to identify the individual. The data can be updated every time the display device is used.

[0078] The path through S1, S5, and S6 is an operation for verifying the above data with data relating to shaking output from the sensor 120 in real time and authenticating the individual. For the verification, artificial intelligence (AI) that has deep-learned the individual's accumulated data relating to shaking can be used. Note that this operation can be performed after the individual's information is stored in the database. In this way, the sensor 120 can be used to perform individual authentication.

[0079] If an individual can be identified, the orientation of the display device 100C that the individual prefers to use can be known, and the default display orientation can be set in advance. When the angle of the display device 100C is determined by the sensor 120 alone, the sensor 120 may react sensitively to a slight shaking of the display device 100C. In such a situation, the image may rotate frequently, and it may take time to be able to view the image normally. This may also result in unnecessary power consumption. By setting the display orientation as the default, the time required for viewing can be shortened and power consumption can be reduced.

[0080] For example, if an individual often holds display device 100C as shown in Fig. 9A, display A can be set as the default. Conversely, if an individual often holds display device 100C as shown in Fig. 9B, display C can be set as the default. Note that this function may not be used and only the operation using sensor 120 may be performed.

[0081] 8C and 8D are diagrams for explaining a display device 100D having a battery built in the housing 102a. The display device 100D has an easy-to-grip grip section 106 at the end of the housing 102a, and the battery 117 can be built in the grip section 106. The center of gravity of the display device 100D is located in the grip section 106 that houses the heavy battery 117, so that the display device 100D can be easily held. When the display device 100D is unfolded flat, the grip section serves as a leg, so that the display device can be used on a desk in a stable form. Also, the display surface is inclined, so that the visibility can be improved.

[0082] 8B and 8D, it is preferable to provide a protection circuit 118 for the battery 117. It is preferable to use a lithium ion battery as the battery 117, which can increase the capacity, but on rare occasions, an abnormality (such as a micro-short circuit) inside the battery can cause a fire.

[0083] 11A, the protection circuit 118 may include a comparator 121, a transistor 122, and a capacitor 123. The comparator 121 detects the voltage (V bat ) and a reference potential (V ref ) and V bat V ref When the voltage drops below V, the logical value output from the output terminal (OUT) is inverted. ref can be written to and held at a node N to which the transistor 122, the capacitor 123, and one of the input terminals of the comparator 121 are connected.

[0084] Since the potential written to the node N can be held using the transistor 122 and the capacitor 123, a circuit in which the transistor 122 and the capacitor 123 are combined can be called a memory circuit or a dynamic oxide semiconductor random access memory (DOSRAM). Since the DOSRAM can be configured with one transistor and one capacitor, high memory density can be achieved. In addition, by using an OS transistor, the data retention period can be increased.

[0085] V ref is rewritten at regular intervals in response to a change in voltage due to charging and discharging of the battery 117. In the protection circuit 118, an OS transistor is preferably used for the transistor 122. An OS transistor has a low off-state current and can hold the potential written to the node N for a long period of time without substantial fluctuation.

[0086] In the case where an OS transistor is used as the transistor 122, the protection circuit 118 including the memory circuit is sometimes referred to as a battery operating system (BTOS) or a battery oxide semiconductor.

[0087] 11B, battery 117 is electrically connected to protection circuit 118, and the output of protection circuit 118 is connected to control circuit 119. When protection circuit 118 detects a sudden voltage drop or the like of battery 117, it inverts the logical value of the signal it outputs to control circuit 119. At this time, control circuit 119 performs control to cut off charging and discharging of battery 117, thereby ensuring the safety of the user.

[0088] 8B and 8D, it is preferable to provide antennas 125 and 126 in housing 102a. Antenna 125 is an antenna for fourth generation mobile communication system (4G) communication, and antenna 126 is an antenna for fifth generation mobile communication system (5G) communication. 5G communication can perform high-speed communication 10 to 20 times faster than 4G communication.

[0089] 8B and 8D, a configuration in which both antenna 125 and antenna 126 are provided is illustrated, but the present invention is not limited thereto. For example, a configuration in which only antenna 125 or only antenna 126 is provided within housing 102a may be used. Also, in Figs. 8B and 8D, a configuration in which one each of antenna 125 and antenna 126 is provided is illustrated, but the present invention is not limited thereto. For example, a configuration in which multiple antennas 125 or multiple antennas 126 are provided may be used.

[0090] Providing both antenna 125 and antenna 126 on housing 102a facilitates good communication. Users often use (place, hold, etc.) their phones in a way that makes the display easy to see even when folded, and so often orient housing 102a in the direction from which the radio waves are traveling (upward, outward), making it easier to receive radio waves.

[0091] 8A and 8B show an example in which the shape of the housing 102c is made thicker than the other housings to house a battery or the like, but the shape of the housing 102a may be made thicker than the other housings as in the display device 100E shown in Fig. 12A. In this case, the hinge 103a corresponding to the outward bending can be appropriately bent to allow the display device to be placed on a desk or the like in a well-balanced manner.

[0092] In addition, since the flat surface of the display surface can be divided into two at the hinge 103a, appropriate images can be assigned to each flat surface when multiple images are displayed, improving visibility. In addition, one of the flat surfaces can be made non-display to perform power saving operation.

[0093] 12B, the housing 102c of the display device 100C may further include a power receiving coil 107 and a power receiving circuit 108. By overlapping the power receiving coil 107 and a power transmitting coil of the charger 109, wireless charging can be performed.

[0094] When a current flows through the power transmission coil of the charger 109, a magnetic flux is generated, and a current is generated in the power receiving coil 107 by electromagnetic induction. The current is rectified in the power receiving circuit 108 and is used to charge a battery connected to the power receiving circuit 108.

[0095] In the display device 100C, the housing 102c, which has a center of gravity, can be placed on the charger 109 by contacting it with the charger 109. Therefore, as shown in FIG. 12B, the display device 100C can be stably placed on the charger 109 even when not folded. Also, the display device 100C can be used without impairing visibility even during charging. The power receiving coil 107 can be provided on all, any two, or any one of the housings 102a, 102b, and 102c.

[0096] <Display operation example 1> 13A to 13C are diagrams illustrating an example of an operation common to the display devices 100A to 100E of one embodiment of the present invention. Note that FIGS. 13A to 13C show a case where the display device 100A is used as a representative example. FIG. 13A shows an operation in which the curved surface 104a is in a non-display state when the flat portion of the region 101a is in a display state in a folded state. At this time, it is preferable that the folded and invisible region (region 101b and region 101c including the curved surface 104b) is also in a non-display state, as shown in the cross-sectional view of B1-B2 in FIG. 13B.

[0097] Alternatively, as shown in Fig. 13C, when the flat portion of the area 101a is in a non-display state, the curved surface 104a may be in a display state. As described above, it is preferable that the area that is folded and cannot be seen is also in a non-display state. In this way, in the folded state, by making only a part of the area a display state, it is possible to perform power saving operation.

[0098] <Display operation example 2> 14A to 14C are diagrams illustrating an example in which the display unit of each of display devices 100A to 100D according to one embodiment of the present invention is divided into three screens and used.

[0099] 14A shows an example of a well-balanced installation on a desk by making the angle between the housing 102c and the housing 102b an obtuse angle and the angle between the housing 102b and the housing 102a an acute angle. By using the housing 102a as a leg, it can be used like a laptop computer. For example, a keyboard 131 is displayed in the area 101c, an icon 132 is displayed on the curved surface 104b, and an image 130 of an application software is displayed in the area 101b, and operations can be performed by touching the screen.

[0100] At this time, if the area 101a is set to a mode in which the same image 130 as that in the area 101b is displayed in the area 101a as well, the person opposite can see the same image with good visibility, as shown in Fig. 14B. Alternatively, the area 101a may be set to a non-display state and the device may be operated in a power-saving mode as shown in Fig. 14C.

[0101] <Display operation example 3> 15A to 15C are diagrams illustrating an example in which the display unit of each of display devices 100A to 100E according to one embodiment of the present invention is divided into two screens for use.

[0102] 15A is a diagram showing an example of a well-balanced installation on a desk by setting the angle between housing 102a and housing 102b to be equal to or greater than approximately 60° and less than 180° (for example, approximately 90°) and the angle between housing 102b and housing 102c to be approximately 180°. Visibility can be improved by making areas 101b and 101c into a continuous flat surface to make the screen larger and by using housing 102a as a leg to tilt the display surface (areas 101b and 101c).

[0103] At this time, as shown in FIG. 15B, the area 101a may be in a non-display state and the device may be operated in a power saving mode.

[0104] 15C is a diagram showing an example of well-balanced installation on a desk by setting the angle between housing 102c and housing 102b to be less than approximately 180° and equal to or greater than 90° (for example, approximately 135°) and the angle between housing 102b and housing 102a to be approximately 180°. By placing housing 102a and housing 102b parallel to a flat surface such as a desk, input using stylus 150 or the like can be facilitated. Also, by tilting area 101c, visibility can be improved.

[0105] <Application Example 1> 16A and 16B are diagrams showing an example of application of the display device shown in the present embodiment as an information terminal such as a smartphone. Elements common to the display device described above are given the same reference numerals. Display device 200 has audio input / output units 135a and 135b, cameras 136a and 136b, sensors 137 and 120.

[0106] When one of the voice input / output units 135a, 135b functions as a microphone, the other can function as a speaker. Therefore, when using the telephone function, conversation can be carried out without inconvenience no matter which way the device is held. The microphone function and the speaker function can be switched by the sensor 120 that detects the tilt. Similarly, the cameras 136a, 136b can be prioritized by the sensor 120.

[0107] The input / output units 135a and 135b may each have both a device that functions as a microphone and a device that functions as a speaker, or may each have one device that has both functions.

[0108] In addition, both the input / output units 135a and 135b can function as microphones to record stereo sound, and both the input / output units 135a and 135b can function as speakers to play stereo sound.

[0109] In addition, it is also possible to capture a 3D image by operating both cameras 136a and 136b. The sensor 137 is an optical sensor, and can adjust the brightness of the display to make it easier to see according to the illuminance of the surroundings.

[0110] 16B, a display panel 138 may be provided on the rear surface of the display device 200, opposite to the front surface on which the display panel 101 is provided. The display panel 138 can display the same image as the display panel 101, and can also be used as a sub-display for displaying simple information, pictures, patterns, photographs, etc., or as lighting. A display panel using a light-emitting device or a liquid crystal device can be used for the display panel 138, and low-power electronic paper can also be used. A display panel using a hard substrate as a support can also be used for the display panel 138.

[0111] As shown in Fig. 17A, the display panel 138 may be provided on each of the housings 102a to 102c. Alternatively, as shown in Fig. 17B, a flexible display panel 139 may be provided on the rear surface of the display device 200. In this case, since the display panel 139 can be bent, it can be provided across the housings 102a to 102c in the same way as the display panel 101 provided on the front surface.

[0112] 17C, a solar cell 140 may be provided on the rear surface of the display device 200. The power generated by the solar cell 140 can be used to charge the battery in the display device 200, and can also be supplied to the outside via the external interface 145.

[0113] 17C shows an example of a solar cell having a hard support. As the solar cell, for example, a silicon solar cell with a crystalline silicon photoelectric conversion layer, or a solar cell with a tandem structure of a silicon solar cell and a perovskite solar cell can be used.

[0114] Alternatively, as shown in Fig. 17D, it may be a solar cell having a flexible substrate as a support. As the solar cell, for example, a thin-film solar cell 141 such as an amorphous silicon solar cell, a CIGS (Cu-In-Ga-Se) type solar cell, an organic solar cell, or a perovskite type solar cell can be used. The solar cell having a flexible substrate as a support can be provided across the housings 102a to 102c, similar to the display panel 139.

[0115] <Application Example 2> 18A and 18B are diagrams showing examples of the case where the display portions of the display devices 100A to 100D of one embodiment of the present invention are used differently depending on the purpose.

[0116] 18A and 18B are diagrams showing an example in which the display device according to the present embodiment is applied as an order terminal for a restaurant or the like. Elements common to the above-mentioned display devices are given the same reference numerals. The display device 210 includes a transmitting / receiving unit 146, a speaker 147, a camera 148, a microphone 149, and the like. The display device 210 may have a function of a general tablet computer in addition to the function of one embodiment of the present invention.

[0117] Normally, it can be folded as shown in FIG. 18A, and the functions of calling a store clerk and the intercom can be used. When unfolded, a menu is displayed and an order can be placed. The order details can be transmitted via the transmitting / receiving unit 146. In addition, the total amount of the order can be displayed, and payment can be made using a barcode captured by the camera 148.

[0118] FIG. 19 is a block diagram showing an example in which the display device shown in this embodiment is applied as a television device.

[0119] In FIG. 19, the components are classified by function and illustrated as independent blocks; however, in reality, it is difficult to completely separate the components by function, and one component may be involved in multiple functions.

[0120] The television device 600 includes a control unit 601, a memory unit 602, a communication control unit 603, an image processing circuit 604, a decoder circuit 605, a video signal receiving unit 606, a timing controller 607, a source driver 608, a gate driver 609, a display panel 620, and the like.

[0121] The display panel 620 corresponds to the display panel 101 described in the first embodiment, and other elements can be included in any one of the housings 102a to 102c. Note that some elements such as the source driver 608 and the gate driver 609 may be elements of the display panel 101.

[0122] The control unit 601 can function as, for example, a central processing unit (CPU). For example, the control unit 601 has a function of controlling components such as a storage unit 602, a communication control unit 603, an image processing circuit 604, a decoder circuit 605, and a video signal receiving unit 606 via a system bus 630.

[0123] Signals are transmitted between the control unit 601 and each component via a system bus 630. The control unit 601 also has a function of processing signals input from each component connected via the system bus 630, a function of generating signals to be output to each component, and the like, and is thereby capable of centrally controlling each component connected to the system bus 630.

[0124] The storage unit 602 functions as a register, a cache memory, a main memory, a secondary memory, etc. that the control unit 601 and the image processing circuit 604 can access.

[0125] As a storage device that can be used as the secondary memory, for example, a storage device using a rewritable non-volatile memory can be used, such as a flash memory, MRAM (Magnetoresistive Random Access Memory), PRAM (Phase change RAM), ReRAM (Resistive RAM), FeRAM (Ferroelectric RAM), etc.

[0126] Furthermore, as a storage device that can be used as a temporary memory such as a register, cache memory, or main memory, a volatile memory such as a DRAM (Dynamic RAM) or an SRAM (Static Random Access Memory) may be used.

[0127] For example, a DRAM is used as the RAM provided in the main memory, and a memory space is virtually allocated and used as a working space for the control unit 601. The operating system, application programs, program modules, program data, etc. stored in the storage unit 602 are loaded into the RAM for execution. These data, programs, and program modules loaded into the RAM are directly accessed and operated by the control unit 601.

[0128] On the other hand, ROM can store BIOS (Basic Input / Output System) and firmware that do not require rewriting. As ROM, mask ROM, OTPROM (One Time Programmable Read Only Memory), EPROM (Erasable Programmable Read Only Memory), etc. can be used. As EPROM, UV-EPROM (Ultra-Violet Erasable Programmable Read Only Memory), which allows the stored data to be erased by exposure to ultraviolet light, EEPROM (Electrically Erasable Programmable Read Only Memory), flash memory, etc. can be used.

[0129] Also, a removable storage device may be connectable in addition to the storage unit 602. For example, it is preferable to have a terminal for connecting to a recording medium such as a hard disk drive (HDD) or a solid state drive (SSD) that functions as a storage device, a flash memory, a Blu-ray disk, or a DVD. This allows video to be recorded.

[0130] The communication control unit 603 has a function of controlling communication performed via a computer network. That is, the television device 600 is implemented using the technology of the Internet of Things (IoT).

[0131] The communication control unit 603 controls a control signal for connecting to a computer network in response to, for example, an instruction from the control unit 601, and transmits the control signal to the computer network. This allows connection to and communication with computer networks such as the Internet, which is the basis of the World Wide Web (WWW), an intranet, an extranet, a personal area network (PAN), a local area network (LAN), a campus area network (CAN), a metropolitan area network (MAN), a wide area network (WAN), and a global area network (GAN).

[0132] Furthermore, the communication control unit 603 may have a function of communicating with a computer network or other electronic devices using communication standards such as Wi-Fi (registered trademark), Bluetooth (registered trademark), and ZigBee (registered trademark).

[0133] The communication control unit 603 may have a function of wireless communication. For example, an antenna and a high-frequency circuit (RF circuit) may be provided to transmit and receive RF signals. The high-frequency circuit is a circuit for converting between electromagnetic signals and electric signals in a frequency band determined by the laws of each country, and for communicating with other communication devices wirelessly using the electromagnetic signals. A practical frequency band is generally several tens of kHz to several tens of GHz. The high-frequency circuit connected to the antenna has a high-frequency circuit section corresponding to a plurality of frequency bands, and the high-frequency circuit section may have a configuration including an amplifier, a mixer, a filter, a DSP, an RF transceiver, and the like.

[0134] The video signal receiving unit 606 has, for example, an antenna, a demodulation circuit, and an AD conversion circuit (analog-digital conversion circuit). The demodulation circuit has a function of demodulating a signal input from the antenna. The AD conversion circuit has a function of converting the demodulated analog signal into a digital signal. The signal processed by the video signal receiving unit 606 is sent to the decoder circuit 605.

[0135] The decoder circuit 605 has a function of decoding video data contained in a digital signal input from the video signal receiving unit 606 according to the specifications of the broadcasting standard to be transmitted, and generating a signal to be transmitted to the image processing circuit. For example, the broadcasting standard for 8K broadcasting is H.265 | MPEG-H High Efficiency Video Coding (abbreviation: HEVC).

[0136] Examples of broadcasting waves that can be received by the antenna of the video signal receiving unit 606 include terrestrial waves and radio waves transmitted from satellites. Examples of broadcasting waves that can be received by the antenna include analog broadcasting, digital broadcasting, and also video and audio, or audio only broadcasting. For example, broadcasting waves transmitted in a specific frequency band of the UHF band (approximately 300 MHz to 3 GHz) or the VHF band (30 MHz to 300 MHz) can be received. Also, for example, by using multiple data received in multiple frequency bands, the transfer rate can be increased and more information can be obtained. This makes it possible to display images with a resolution that exceeds full high definition on the display panel 620. For example, images with a resolution of 4K2K, 8K4K, 16K8K, or higher can be displayed.

[0137] Also, the video signal receiving unit 606 and the decoder circuit 605 may be configured to generate a signal to be transmitted to the image processing circuit 604, using broadcast data transmitted by a data transmission technique via a computer network. In this case, if the received signal is a digital signal, the video signal receiving unit 606 does not need to have a demodulation circuit, an AD conversion circuit, and the like.

[0138] The image processing circuit 604 has a function of generating a video signal to be output to a timing controller 607 based on a video signal input from a decoder circuit 605 .

[0139] The timing controller 607 has a function of generating signals (signals such as a clock signal and a start pulse signal) to be output to the gate driver 609 and the source driver 608 based on a synchronization signal included in the video signal etc. processed by the image processing circuit 604. Furthermore, the timing controller 607 has a function of generating a video signal to be output to the source driver 608 in addition to the above signals.

[0140] The display panel 620 has a plurality of pixels 621. Each pixel 621 is driven by a signal supplied from a gate driver 609 and a source driver 608. Here, an example of a display panel having a resolution of 7680×4320 pixels according to the 8K4K standard is shown. Note that the resolution of the display panel 620 is not limited to this, and may be a resolution according to a standard such as full high vision (1920×1080 pixels) or 4K2K (3840×2160 pixels).

[0141] The control unit 601 and the image processing circuit 604 shown in Fig. 19 may have a configuration including, for example, a processor. For example, the control unit 601 may use a processor functioning as a CPU. Also, the image processing circuit 604 may use other processors such as a DSP (Digital Signal Processor) or a GPU (Graphics Processing Unit). Also, the control unit 601 and the image processing circuit 604 may have a configuration in which the processor is realized by a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array) or an FPAA (Field Programmable Analog Array).

[0142] The processor performs various data processing and program control by interpreting and executing commands from various programs. The programs that can be executed by the processor may be stored in a memory area of ​​the processor, or may be stored in a storage device provided separately.

[0143] Furthermore, two or more of the functions of the control unit 601, the storage unit 602, the communication control unit 603, the image processing circuit 604, the decoder circuit 605, the video signal receiving unit 606, and the timing controller 607 may be integrated into one IC chip to configure a system LSI. For example, the system LSI may include a processor, a decoder circuit, a tuner circuit, an AD conversion circuit, a DRAM, an SRAM, and the like.

[0144] Note that a transistor that uses an oxide semiconductor in a channel formation region and has an extremely low off-current can also be used in the control unit 601 and ICs and the like of other components. Since the off-current of the transistor is extremely low, the transistor can be used as a switch for holding charge (data) flowing into a capacitance that functions as a memory, thereby ensuring a long data holding period. By using this characteristic in a register or cache memory of the control unit 601, etc., the control unit 601 is operated only when necessary, and information from the immediately preceding process is saved in the memory in other cases, thereby enabling normally-off computing. This allows the power consumption of the television device 600 to be reduced.

[0145] Note that the configuration of the television device 600 in Fig. 19 is an example, and it is not necessary to include all of the components. The television device 600 only needs to have necessary components among the components shown in Fig. 19. Furthermore, the television device 600 may have components other than those shown in Fig. 19.

[0146] For example, the television device 600 may have an external interface, an audio output unit, a touch panel unit, a sensor unit, a camera unit, and the like in addition to the configuration shown in Fig. 19. For example, the external interface may be an external connection terminal such as a Universal Serial Bus (USB) terminal, a Local Area Network (LAN) connection terminal, a power supply terminal, an audio output terminal, an audio input terminal, a video output terminal, and a video input terminal, a transceiver for optical communication using infrared light, visible light, ultraviolet light, and the like, a physical button provided on the housing, and the like. In addition, for example, the audio input / output unit may be a sound controller, a microphone, a speaker, and the like.

[0147] The image processing circuit 604 will now be described in more detail.

[0148] The image processing circuit 604 preferably has a function of executing image processing based on a video signal input from the decoder circuit 605 .

[0149] The image processing includes, for example, noise removal processing, tone conversion processing, color correction processing, brightness correction processing, etc. The color correction processing and brightness correction processing include, for example, gamma correction.

[0150] Furthermore, the image processing circuit 604 preferably has a function of executing processes such as inter-pixel interpolation processing associated with up-conversion of the resolution and inter-frame interpolation processing associated with up-conversion of the frame frequency.

[0151] For example, noise removal processing removes various types of noise, such as mosquito noise that occurs around the contours of characters, block noise that occurs in high-speed moving images, random noise that causes flickering, and dot noise that occurs when up-converting resolution.

[0152] The gradation conversion process is a process of converting the gradation of an image into a gradation corresponding to the output characteristics of the display panel 620. For example, when increasing the number of gradations, a process of smoothing the histogram can be performed by interpolating and assigning gradation values ​​corresponding to each pixel to an image input with a small number of gradations. High dynamic range (HDR) processing, which widens the dynamic range, is also included in the gradation conversion process.

[0153] In addition, pixel interpolation processing interpolates data that does not exist when the resolution is up-converted. For example, the data is interpolated to display intermediate colors between pixels surrounding the target pixel by referencing the pixels surrounding the target pixel.

[0154] The color correction process is a process for correcting the color tone of an image. The brightness correction process is a process for correcting the brightness (brightness contrast) of an image. For example, the type of lighting, brightness, or color purity of the space in which the television device 600 is installed is detected, and the brightness and color tone of the image displayed on the display panel 620 are corrected accordingly to be optimal. Alternatively, the television device 600 may have a function for comparing the image to be displayed with images of various scenes in an image list stored in advance, and correcting the image to be displayed to a brightness and color tone suitable for the image of the closest scene.

[0155] Inter-frame interpolation generates an image of a frame (interpolated frame) that does not actually exist when the frame frequency of a video to be displayed is increased. For example, an image of an interpolated frame to be inserted between two images is generated from the difference between the two images. Alternatively, multiple images of an interpolated frame can be generated between two images. For example, when the frame frequency of the video signal input from the decoder circuit 605 is 60 Hz, the frame frequency of the video signal to be output to the timing controller 607 can be increased to 2 times (120 Hz), 4 times (240 Hz), or 8 times (480 Hz), by generating multiple interpolated frames.

[0156] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be appropriately combined with other configuration examples or drawings.

[0157] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0158] (Embodiment 2) In this embodiment, a structure example of a display panel that can be used for a display device of one embodiment of the present invention will be described.

[0159] <Configuration example> 20 shows a top view of a display panel 700. The display panel 700 is a display panel to which a flexible supporting substrate 745 is applied and which can be used as a flexible display. The display panel 700 has a pixel portion 702 provided over the flexible supporting substrate 745. A source driver circuit portion 704, a pair of gate driver circuit portions 706, wirings 710, and the like are provided over the supporting substrate 745. The pixel portion 702 is provided with a plurality of display devices.

[0160] Further, an FPC terminal portion 708 to which an FPC 716 (Flexible printed circuit) is connected is provided on a part of the support substrate 745. Various signals and the like are supplied to each of the pixel portion 702, the source driver circuit portion 704, and the gate driver circuit portion 706 by the FPC 716 via the FPC terminal portion 708 and wiring 710.

[0161] A pair of gate driver circuit units 706 are provided on both sides of the pixel unit 702. The gate driver circuit unit 706 and the source driver circuit unit 704 may each be formed separately on a semiconductor substrate or the like and be in the form of a packaged IC chip. The IC chip can be mounted on a support substrate 745 by COF (Chip On Film) technology or the like.

[0162] It is preferable that OS transistors be used as transistors in the pixel portion 702, the source driver circuit portion 704, and the gate driver circuit portion 706.

[0163] A light-emitting device or the like can be used as the display device provided in the pixel unit 702. Examples of the light-emitting device include self-luminous light-emitting devices such as LEDs (Light Emitting Diodes), OLEDs (Organic LEDs), QLEDs (Quantum-dot LEDs), and semiconductor lasers. In addition, liquid crystal devices such as transmissive liquid crystal devices, reflective liquid crystal devices, and semi-transmissive liquid crystal devices can also be used as the display device. In addition, a shutter-type or optical interference-type MEMS (Micro Electro Mechanical Systems) device, a microcapsule type, an electrophoresis type, an electrowetting type, or an electronic liquid powder (registered trademark) type display device can also be used.

[0164] 20 shows an example in which a portion of the support substrate 745 on which the FPC terminal portion 708 is provided has a protruding shape. A part of the support substrate 745 including the FPC terminal portion 708 can be folded back to the back side in an area P1 in FIG. 20. By folding back a part of the support substrate 745, the display panel 700 can be mounted on an electronic device or the like in a state in which the FPC 716 is disposed so as to overlap the back side of the pixel portion 702, thereby enabling space saving and miniaturization of the electronic device or the like.

[0165] An IC 717 is mounted on an FPC 716 connected to the display panel 700. The IC 717 has a function as, for example, a source driver circuit. In this case, the source driver circuit unit 704 in the display panel 700 can be configured to include at least one of a protection circuit, a buffer circuit, a demultiplexer circuit, and the like.

[0166] <Cross-section configuration example> A configuration using an organic EL display device will be described below with reference to Figures 21 and 22. Figures 21 and 22 are schematic cross-sectional views of the display panel 700 shown in Figure 20 taken along dashed line ST.

[0167] First, common parts of the display panels shown in FIG. 21 and FIG. 22 will be described.

[0168] 21 and 22 show cross sections including a pixel portion 702, a gate driver circuit portion 706, and an FPC terminal portion 708. The pixel portion 702 includes a transistor 750 and a capacitor 790. The gate driver circuit portion 706 includes a transistor 752.

[0169] The transistor 750 and the transistor 752 are transistors in which an oxide semiconductor is used for a semiconductor layer in which a channel is formed. Note that the present invention is not limited to this, and a transistor in which silicon (amorphous silicon, polycrystalline silicon, or single crystal silicon) or an organic semiconductor is used for the semiconductor layer can also be used.

[0170] The transistor used in this embodiment has an oxide semiconductor film that is highly purified and in which formation of oxygen vacancies is suppressed. The off-state current of the transistor can be significantly reduced. Therefore, a pixel including such a transistor can hold an electric signal such as an image signal for a long time and can set a long interval for writing an image signal or the like. Thus, the frequency of a refresh operation can be reduced, leading to reduced power consumption.

[0171] In addition, the transistor used in this embodiment can achieve a relatively high field-effect mobility and thus can be driven at high speed. For example, by using such a transistor capable of high speed driving in a display panel, a switching transistor in a pixel portion and a driver transistor used in a driver circuit portion can be formed over the same substrate. That is, a configuration without using a driver circuit formed using a silicon wafer or the like is possible, and the number of components in a display device can be reduced. In addition, by using a transistor capable of high speed driving in the pixel portion, a high-quality image can be provided.

[0172] The capacitor 790 has a lower electrode formed by processing the same film as the first gate electrode of the transistor 750, and an upper electrode formed by processing the same metal oxide film as the semiconductor layer. The upper electrode has a low resistance like the source region and drain region of the transistor 750. In addition, a part of an insulating film functioning as the first gate insulating layer of the transistor 750 is provided between the lower electrode and the upper electrode. That is, the capacitor 790 has a stacked structure in which an insulating film functioning as a dielectric film is sandwiched between a pair of electrodes. In addition, a wiring obtained by processing the same film as the source electrode and drain electrode of the transistor 750 is connected to the upper electrode.

[0173] In addition, an insulating layer 770 functioning as a planarization film is provided over the transistor 750, the transistor 752, and the capacitor 790.

[0174] The transistor 750 in the pixel portion 702 and the transistor 752 in the gate driver circuit portion 706 may have different structures. For example, a top-gate transistor may be used for one of them, and a bottom-gate transistor may be used for the other. Note that the source driver circuit portion 704 is similar to the gate driver circuit portion 706.

[0175] The FPC terminal portion 708 has a wiring 760, a part of which functions as a connection electrode, an anisotropic conductive film 780, and an FPC 716. The wiring 760 is electrically connected to a terminal of the FPC 716 via the anisotropic conductive film 780. Here, the wiring 760 is formed of the same conductive film as the source and drain electrodes of the transistor 750 and the like.

[0176] Next, a display panel 700 shown in FIG. 21 will be described.

[0177] 21 includes a supporting substrate 745 and a supporting substrate 740. As the supporting substrate 745 and the supporting substrate 740, for example, a flexible substrate such as a glass substrate or a plastic substrate can be used.

[0178] A transistor 750, a transistor 752, a capacitor 790, and the like are provided over an insulating layer 744. A support substrate 745 and the insulating layer 744 are attached to each other by an adhesive layer 742.

[0179] The display panel 700 also includes a light emitting device 782, a colored layer 736, a light blocking layer 738, and the like.

[0180] The light-emitting device 782 includes a conductive layer 772, an EL layer 786, and a conductive layer 788. The conductive layer 772 is electrically connected to a source electrode or a drain electrode of the transistor 750. The conductive layer 772 is provided over an insulating layer 770 and functions as a pixel electrode. An insulating layer 730 is provided to cover an end portion of the conductive layer 772, and an EL layer 786 and a conductive layer 788 are stacked over the insulating layer 730 and the conductive layer 772.

[0181] The conductive layer 772 can be formed using a material that is reflective to visible light. For example, a material containing aluminum, silver, or the like can be used. The conductive layer 788 can be formed using a material that transmits visible light. For example, an oxide material containing indium, zinc, tin, or the like can be used. Therefore, the light-emitting device 782 is a top-emission light-emitting device that emits light to the side opposite to the formation surface (the supporting substrate 740 side).

[0182] The EL layer 786 includes an organic compound or an inorganic compound such as quantum dots, etc. The EL layer 786 includes a light-emitting material that emits blue light when a current flows through it.

[0183] Examples of luminescent materials include fluorescent materials, phosphorescent materials, thermally activated delayed fluorescence (TADF) materials, inorganic compounds (quantum dot materials, etc.), etc. Examples of materials that can be used for quantum dots include colloidal quantum dot materials, alloy-type quantum dot materials, core-shell type quantum dot materials, core-type quantum dot materials, etc.

[0184] The light-shielding layer 738 and the colored layer 736 are provided on one surface of the insulating layer 746. The colored layer 736 is provided at a position overlapping with the light-emitting device 782. The light-shielding layer 738 is provided in a region of the pixel portion 702 that does not overlap with the light-emitting device 782. The light-shielding layer 738 may also be provided overlapping with the gate driver circuit portion 706, etc.

[0185] The supporting substrate 740 is bonded to the other surface of the insulating layer 746 by an adhesive layer 747. The supporting substrate 740 and the supporting substrate 745 are bonded to each other by a sealing layer 732.

[0186] Here, a light-emitting material that emits white light is applied as the EL layer 786 of the light-emitting device 782. The white light emitted by the light-emitting device 782 is colored by the coloring layer 736 and emitted to the outside. The EL layer 786 is provided across pixels that exhibit different colors. In the pixel portion, pixels provided with the coloring layer 736 that transmits any of red (R), green (G), and blue (B) are arranged in a matrix form, so that the display panel 700 can display full colors.

[0187] A semi-transparent and semi-reflective conductive film may be used as the conductive layer 788. In this case, a microresonator (microcavity) structure may be realized between the conductive layer 772 and the conductive layer 788, and a configuration may be adopted in which light of a specific wavelength is intensified and emitted. In this case, an optical adjustment layer for adjusting the optical distance may be disposed between the conductive layer 772 and the conductive layer 788, and the thickness of the optical adjustment layer may be made different between pixels of different colors, thereby increasing the color purity of the light emitted from each pixel.

[0188] When the EL layer 786 is formed in an island shape for each pixel or in a stripe shape for each pixel row, that is, when the EL layer 786 is formed by coloring, the colored layer 736 and the optical adjustment layer described above may not be provided.

[0189] Here, it is preferable to use an inorganic insulating film functioning as a barrier film with low moisture permeability for each of the insulating layers 744 and 746. By sandwiching the light-emitting device 782, the transistor 750, and the like between the insulating layers 744 and 746, deterioration of these elements is suppressed, and a highly reliable display panel can be realized.

[0190] A display panel 700A shown in Fig. 22 includes a resin layer 743 between the adhesive layer 742 and the insulating layer 744 shown in Fig. 21. Also, a protective layer 749 is provided instead of the support substrate 740.

[0191] The resin layer 743 is a layer containing an organic resin such as polyimide or acrylic. The insulating layer 744 contains an inorganic insulating film such as silicon oxide, silicon oxynitride, or silicon nitride. The resin layer 743 and the support substrate 745 are attached to each other by an adhesive layer 742. The resin layer 743 is preferably thinner than the support substrate 745.

[0192] The protective layer 749 is attached to the sealing layer 732. A glass substrate, a resin film, or the like can be used as the protective layer 749. In addition, as the protective layer 749, an optical member such as a polarizing plate (including a circular polarizing plate) or a scattering plate, an input device such as a touch sensor panel, or a configuration in which two or more of these are laminated may be used.

[0193] In addition, the EL layer 786 of the light-emitting device 782 is provided in an island shape on the insulating layer 730 and the conductive layer 772. By creating the EL layer 786 so that each subpixel has a different light emission color, a color display can be realized without using the colored layer 736.

[0194] A protective layer 741 is provided to cover the light-emitting device 782. The protective layer 741 has a function of preventing impurities such as water from diffusing into the light-emitting device 782. The protective layer 741 has a laminated structure in which an insulating layer 741a, an insulating layer 741b, and an insulating layer 741c are laminated in this order from the conductive layer 788 side. In this case, it is preferable to use an inorganic insulating film having a high barrier property against impurities such as water for the insulating layer 741a and the insulating layer 741c, and an organic insulating film functioning as a planarizing film for the insulating layer 741b. It is also preferable that the protective layer 741 is provided so as to extend to the gate driver circuit section 706.

[0195] In addition, it is preferable that the organic insulating film covering the transistor 750, the transistor 752, and the like is formed in an island shape inside the sealing layer 732. In other words, it is preferable that the end of the organic insulating film is located inside the sealing layer 732 or in a region overlapping with the end of the sealing layer 732. FIG. 22 shows an example in which the insulating layer 770, the insulating layer 730, and the insulating layer 741b are processed into an island shape. For example, in the portion overlapping with the sealing layer 732, the insulating layer 741c and the insulating layer 741a are provided in contact with each other. In this way, by configuring the surface of the organic insulating film covering the transistor 750 and the transistor 752 not to be exposed outside the sealing layer 732, it is possible to suitably prevent water or hydrogen from diffusing from the outside to the transistor 750 and the transistor 752 through the organic insulating film. This suppresses fluctuations in the electrical characteristics of the transistors, and realizes a display device with extremely high reliability.

[0196] 22, the bendable region P1 has a portion where inorganic insulating films such as the insulating layer 744 are not provided, in addition to the support substrate 745 and the adhesive layer 742. In the region P1, the insulating layer 770 containing an organic material covers the wiring 760 to prevent the wiring 760 from being exposed. By providing as little inorganic insulating film as possible in the bendable region P1 and by using a configuration in which only a conductive layer containing a metal or alloy and a layer containing an organic material are laminated, it is possible to prevent cracks from occurring when the panel is bent. By not providing the support substrate 745 in the region P1, a portion of the display panel 700A can be bent with an extremely small radius of curvature.

[0197] 22, a conductive layer 761 is provided over the protective layer 741. The conductive layer 761 can be used as a wiring or an electrode.

[0198] In addition, when a touch sensor is provided over the display panel 700A, the conductive layer 761 can function as an electrostatic shielding film for preventing electrical noise generated when a pixel is driven from being transmitted to the touch sensor. In this case, a predetermined constant potential may be applied to the conductive layer 761.

[0199] Alternatively, the conductive layer 761 can be used as, for example, an electrode of a touch sensor. This allows the display panel 700A to function as a touch panel. For example, the conductive layer 761 can be used as an electrode or wiring of a capacitive touch sensor. In this case, the conductive layer 761 can be used as a wiring or electrode to which a detection circuit is connected, or a wiring or electrode to which a sensor signal is input. In this way, by fabricating a touch sensor on the light-emitting device 782, the number of components can be reduced, and the manufacturing cost of electronic devices and the like can be reduced.

[0200] The conductive layer 761 is preferably provided in a portion that does not overlap with the light-emitting device 782. For example, the conductive layer 761 can be provided in a portion that overlaps with the insulating layer 730. This eliminates the need to use a transparent conductive film with relatively low conductivity as the conductive layer 761, and allows the use of a metal or alloy with high conductivity, thereby improving the sensitivity of the sensor.

[0201] Note that the type of the touch sensor that can be configured using the conductive layer 761 is not limited to the capacitance type, and various types such as a resistive film type, a surface acoustic wave type, an infrared type, an optical type, and a pressure sensitive type can be used. Alternatively, two or more of these types may be used in combination.

[0202] <Components> Components such as transistors that can be applied to a display device will be described below.

[0203] [Transistor] The transistor includes a conductive layer functioning as a gate electrode, a semiconductor layer, a conductive layer functioning as a source electrode, a conductive layer functioning as a drain electrode, and an insulating layer functioning as a gate insulating layer.

[0204] Note that the structure of a transistor included in a display device of one embodiment of the present invention is not particularly limited. For example, a planar transistor, a staggered transistor, or an inverted staggered transistor may be used. In addition, the transistor may have either a top-gate type or a bottom-gate type structure. Alternatively, gate electrodes may be provided above and below a channel.

[0205] The crystallinity of a semiconductor material used in a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor partially having a crystalline region) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0206] <Conductive layer> Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, or alloys containing these as main components. Films containing these materials can be used as a single layer or a laminated structure. For example, there are a single layer structure of an aluminum film containing silicon, a two-layer structure in which an aluminum film is laminated on a titanium film, a two-layer structure in which an aluminum film is laminated on a tungsten film, a two-layer structure in which a copper film is laminated on a copper-magnesium-aluminum alloy film, a two-layer structure in which a copper film is laminated on a titanium film, a two-layer structure in which a copper film is laminated on a tungsten film, a three-layer structure in which a titanium film or titanium nitride film is laminated on the titanium film or titanium nitride film, and a three-layer structure in which an aluminum film or copper film is laminated on the titanium film or titanium nitride film, and a three-layer structure in which an aluminum film or copper film is laminated on the molybdenum film or molybdenum nitride film is laminated on the molybdenum film or molybdenum nitride film is laminated on the molybdenum film or molybdenum nitride film. Alternatively, oxides such as indium oxide, tin oxide, zinc oxide, etc. may be used. Furthermore, copper containing manganese is preferably used because it enhances the controllability of the shape by etching.

[0207] <Insulating layer> Examples of insulating materials that can be used for each insulating layer include resins such as acrylic and epoxy, resins having siloxane bonds, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0208] Moreover, the light emitting device is preferably provided between a pair of insulating films with low water permeability, which can prevent impurities such as water from entering the light emitting device and suppress deterioration of the reliability of the device.

[0209] Examples of the insulating film having low water permeability include a film containing nitrogen and silicon, such as a silicon nitride film or a silicon nitride oxide film, and a film containing nitrogen and aluminum, such as an aluminum nitride film. In addition, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, etc. may also be used.

[0210] For example, the water vapor permeability of a low-permeability insulating film is 1×10 -5 [g / (m 2 ·day)] or less, preferably 1 × 10 -6 [g / (m 2 ·day)] or less, preferably 1×10 -7 [g / (m 2 ·day)] or less, and more preferably 1×10 -8 [g / (m 2 ·day)] or less.

[0211] The above is a description of the components.

[0212] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be appropriately combined with other configuration examples or drawings.

[0213] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0214] (Embodiment 3) In this embodiment, a configuration example of a display device will be described with reference to FIGS. 23A, 23B, and 23C.

[0215] 23A includes a pixel portion 502, a driver circuit portion 504, a protective circuit 506, and a terminal portion 507. Note that the protective circuit 506 does not necessarily have to be provided.

[0216] The pixel section 502 has a plurality of pixel circuits 501 that drive a plurality of display devices arranged in X rows and Y columns (X and Y are each independently a natural number of 2 or more).

[0217] The driver circuit unit 504 has driver circuits such as a gate driver 504a that outputs scanning signals to the gate lines GL_1 to GL_X and a source driver 504b that supplies data signals to the data lines DL_1 to DL_Y. The gate driver 504a may have at least a shift register. The source driver 504b is configured using, for example, a plurality of analog switches. The source driver 504b may also be configured using a shift register.

[0218] The terminal portion 507 refers to a portion provided with terminals for inputting power, control signals, image signals, and the like from an external circuit to the display device.

[0219] The protection circuit 506 is a circuit that, when a potential outside a certain range is applied to a wiring connected to the protection circuit 506, brings the wiring into a conductive state with another wiring. The protection circuit 506 shown in Fig. 23A is connected to various wirings such as a gate line GL that is a wiring between the gate driver 504a and the pixel circuit 501, or a data line DL that is a wiring between the source driver 504b and the pixel circuit 501.

[0220] In addition, the gate driver 504a and the source driver 504b may be provided on the same substrate as the pixel portion 502, or a substrate on which a gate driver circuit or a source driver circuit is separately formed (e.g., a drive circuit substrate formed of a single crystal semiconductor film or a polycrystalline semiconductor film) may be mounted on the substrate by COF, TCP (Tape Carrier Package), COG (Chip On Glass), or the like.

[0221] Furthermore, the pixel circuits 501 shown in FIG. 23A can have the configurations shown in FIGS. 23B and 23C, for example.

[0222] 23B includes a liquid crystal device 570, a transistor 550, and a capacitor 560. The pixel circuit 501 is also connected to a data line DL_n, a gate line GL_m, a potential supply line VL, and the like.

[0223] The potential of one of a pair of electrodes of the liquid crystal device 570 is set appropriately according to the specifications of the pixel circuit 501. The orientation state of the liquid crystal device 570 is set by written data. A common potential (common potential) may be applied to one of the pair of electrodes of the liquid crystal device 570 of each of the multiple pixel circuits 501. Also, a different potential may be applied to one of the pair of electrodes of the liquid crystal device 570 of the pixel circuits 501 in each row.

[0224] 23C includes transistors 552 and 554, a capacitor 562, and a light-emitting device 572. The pixel circuit 501 is connected to a data line DL_n, a gate line GL_m, a potential supply line VL_a, a potential supply line VL_b, and the like.

[0225] A high power supply potential VDD is applied to one of the potential supply lines VL_a and VL_b, and a low power supply potential VSS is applied to the other. A current flowing through the light emitting device 572 is controlled in accordance with the potential applied to the gate of the transistor 554, thereby controlling the light emission brightness from the light emitting device 572.

[0226] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be appropriately combined with other configuration examples or drawings.

[0227] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0228] (Embodiment 4) In the following, a pixel circuit including a memory for correcting a gray scale displayed in a pixel and a display device having the same will be described.

[0229] <Circuit configuration> 24A shows a circuit diagram of a pixel circuit 400. The pixel circuit 400 includes a transistor M1, a transistor M2, a capacitor C1, and a circuit 401. The pixel circuit 400 is also connected to a wiring S1, a wiring S2, a wiring G1, and a wiring G2.

[0230] The transistor M1 has a gate connected to the wiring G1, one of a source and a drain connected to the wiring S1, and the other connected to one electrode of the capacitor C1. The transistor M2 has a gate connected to the wiring G2, one of a source and a drain connected to the wiring S2, and the other connected to the other electrode of the capacitor C1 and the circuit 401.

[0231] The circuit 401 is a circuit including at least one display device. Various devices can be used as the display device, but typically, a light-emitting device such as an organic EL device or an LED device, a liquid crystal device, or a MEMS (Micro Electro Mechanical Systems) device can be applied.

[0232] The node connecting the transistor M1 and the capacitor C1 is referred to as a node N1, and the node connecting the transistor M2 and the circuit 401 is referred to as a node N2.

[0233] In the pixel circuit 400, the potential of the node N1 can be maintained by turning off the transistor M1. Also, the potential of the node N2 can be maintained by turning off the transistor M2. Also, by writing a predetermined potential to the node N1 via the transistor M1 while the transistor M2 is in the off state, the potential of the node N2 can be changed according to the change in the potential of the node N1 due to capacitive coupling via the capacitor C1.

[0234] Here, the transistor including an oxide semiconductor, as exemplified in Embodiment 1, can be used as one or both of the transistors M1 and M2. Therefore, the potentials of the nodes N1 and N2 can be held for a long period of time due to an extremely low off-state current. Note that when the period during which the potentials of the nodes are held is short (specifically, when the frame frequency is 30 Hz or more), a transistor including a semiconductor such as silicon may be used.

[0235] <Driving method example> Next, an example of an operation method of the pixel circuit 400 will be described with reference to Fig. 24B. Fig. 24B is a timing chart relating to the operation of the pixel circuit 400. Note that, for ease of explanation, the influence of various resistances such as wiring resistance, parasitic capacitances of transistors and wiring, threshold voltages of transistors, and the like will not be taken into consideration here.

[0236] 24B, one frame period is divided into a period T1 and a period T2. The period T1 is a period in which a potential is written to the node N2, and the period T2 is a period in which a potential is written to the node N1.

[0237] In the period T1, a potential that turns on the transistor is applied to both the wiring G1 and the wiring G2. In addition, a fixed potential V ref is supplied to the line S2, and the first data potential V w supplies.

[0238] The node N1 is connected to a potential V refThe node N2 is supplied with a first data potential V w Therefore, the capacitance C1 has a potential difference V w -V ref is held.

[0239] In the next period T2, a potential that turns on the transistor M1 is applied to the wiring G1, and a potential that turns off the transistor M2 is applied to the wiring G2. data A predetermined constant potential is applied to the wiring S2, or the wiring S2 may be in a floating state.

[0240] The node N1 receives a second data potential V data At this time, the second data potential V data In response to the change in potential, the potential of the node N2 changes by a potential dV. That is, a potential obtained by adding the first data potential Vw and the potential dV is input to the circuit 401. Note that although the potential dV is shown to be a positive value in FIG. 24B, it may be a negative value. That is, the potential of the second data potential V data is the potential V ref It may be lower.

[0241] Here, the potential dV is roughly determined by the capacitance value of the capacitor C1 and the capacitance value of the circuit 401. When the capacitance value of the capacitor C1 is sufficiently larger than the capacitance value of the circuit 401, the potential dV is equal to the second data potential V data The potential becomes close to

[0242] In this way, the pixel circuit 400 can combine two types of data signals to generate a potential to be supplied to the circuit 401 including a display device, so that the pixel circuit 400 can perform gray scale correction within the pixel circuit 400.

[0243] The pixel circuit 400 can also generate a potential that exceeds the maximum potential that can be supplied to the wirings S1 and S2. For example, when a light-emitting device is used, a high dynamic range (HDR) display can be performed. When a liquid crystal device is used, overdrive driving can be realized.

[0244] <Application Examples> [Example using liquid crystal device] The pixel circuit 400LC shown in Fig. 24C includes a circuit 401LC. The circuit 401LC includes a liquid crystal device LC and a capacitor C2.

[0245] The liquid crystal device LC has one electrode connected to the node N2 and one electrode connected to the capacitance C2, and the other electrode connected to the potential V com2 The other electrode of the capacitor C2 is connected to the wiring to which the potential V com1 Connect with the wiring given.

[0246] The capacitor C2 functions as a storage capacitor. If the capacitor C2 is not required, it can be omitted.

[0247] The pixel circuit 400LC can supply a high voltage to the liquid crystal device LC, and therefore can realize high-speed display by overdriving, can use a liquid crystal material with a high driving voltage, etc. In addition, by supplying a correction signal to the wiring S1 or wiring S2, it is possible to correct the gradation according to the operating temperature, the deterioration state of the liquid crystal device LC, etc.

[0248] [Example using a light-emitting device] The pixel circuit 400EL shown in Fig. 24D includes a circuit 401EL. The circuit 401EL includes a light emitting device EL, a transistor M3, and a capacitor C2.

[0249] The transistor M3 has a gate connected to the node N2 and one electrode of the capacitance C2, and a source and a drain connected to the potential V H The other electrode of the capacitor C2 is connected to a wiring to which a potential Vcom The light-emitting device EL is connected to a wiring that has the other electrode connected to a potential V L Connect with the wiring given.

[0250] The transistor M3 has a function of controlling the current supplied to the light emitting device EL. The capacitor C2 functions as a storage capacitor. The capacitor C2 can be omitted if not required.

[0251] In this example, the anode side of the light emitting device EL is connected to the transistor M3, but the transistor M3 may be connected to the cathode side. H and potential V L The value of can be changed appropriately.

[0252] In the pixel circuit 400EL, a large current can be passed through the light-emitting device EL by applying a high potential to the gate of the transistor M3, and thus, for example, HDR display can be realized. In addition, by supplying a correction signal to the wiring S1 or wiring S2, it is also possible to correct variations in the electrical characteristics of the transistor M3 and the light-emitting device EL.

[0253] It should be noted that the circuits are not limited to those illustrated in FIGS. 24C and 24D, and may be configured to include additional transistors, capacitors, and the like.

[0254] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0255] (Embodiment 5) A configuration example of a pixel in a display panel of one embodiment of the present invention will be described below.

[0256] 25A to 25E show configuration examples of the pixel 300. In FIG.

[0257] The pixel 300 has a plurality of pixels 301. Each of the plurality of pixels 301 functions as a sub-pixel. Since one pixel 300 is composed of a plurality of pixels 301 each exhibiting a different color, full color display can be performed on the display unit.

[0258] Each of the pixels 300 shown in Figures 25A and 25B has three sub-pixels. The pixel 301 in the pixel 300 shown in Figure 25A exhibits a combination of colors: red (R), green (G), and blue (B). The pixel 301 in the pixel 300 shown in Figure 25B exhibits a combination of colors: cyan (C), magenta (M), and yellow (Y).

[0259] Each of the pixels 300 shown in Fig. 25C to Fig. 25E has four sub-pixels. The pixel 301 of the pixel 300 shown in Fig. 25C has a color combination of red (R), green (G), blue (B), and white (W). The brightness of the display unit can be increased by using a sub-pixel that has a white color. The pixel 301 of the pixel 300 shown in Fig. 25D has a color combination of red (R), green (G), blue (B), and yellow (Y). The pixel 301 of the pixel 300 shown in Fig. 25E has a color combination of cyan (C), magenta (M), yellow (Y), and white (W).

[0260] By increasing the number of sub-pixels that function as one pixel and appropriately combining sub-pixels that exhibit colors such as red, green, blue, cyan, magenta, and yellow, it is possible to improve the reproducibility of intermediate tones, thereby improving the display quality.

[0261] In addition, the display device according to one embodiment of the present invention can reproduce color gamuts of various standards. For example, the color gamuts can be reproduced according to the PAL (Phase Alternating Line) standard and the NTSC (National Television System Committee) standard used in television broadcasting, the sRGB (standard RGB) standard and the Adobe RGB standard widely used in display devices used in electronic devices such as personal computers, digital cameras, and printers, the ITU-R BT.709 (International Telecommunication Union Radiocommunication Sector Broadcasting Service (Television) 709) standard used in HDTV (High Definition Television, also called high vision), the DCI-P3 (Digital Cinema Initiatives P3) standard used in digital cinema projection, and the ITU-R BT.2020 (REC.2020 (Recommendation 2020)) standard used in UHDTV (Ultra High Definition Television, also called super high vision).

[0262] Moreover, when the pixels 300 are arranged in a matrix of 1920×1080, a display device capable of full-color display at a resolution of so-called full high-definition (also called "2K resolution", "2K1K", or "2K"). When the pixels 300 are arranged in a matrix of 3840×2160, for example, a display device capable of full-color display at a resolution of so-called ultra high-definition (also called "4K resolution", "4K2K", or "4K"). When the pixels 300 are arranged in a matrix of 7680×4320, for example, a display device capable of full-color display at a resolution of so-called super high-definition (also called "8K resolution", "8K4K", or "8K"). By increasing the number of pixels 300, a display device capable of full-color display at a resolution of 16K or 32K can also be realized.

[0263] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0264] (Embodiment 6) In this embodiment, a cloud-aligned composite oxide semiconductor (CAC-OS) and a c-axis aligned crystalline oxide semiconductor (CAAC-OS) that are metal oxides that can be used for the OS transistor described in the other embodiments will be described.

[0265] <Metal oxide composition> CAC-OS or CAC-metal oxide has a conductive function in a part of the material and an insulating function in a part of the material, and has a function as a semiconductor as a whole. When CAC-OS or CAC-metal oxide is used in the active layer of a transistor, the conductive function is a function of flowing electrons (or holes) as carriers, and the insulating function is a function of not flowing electrons as carriers. By making the conductive function and the insulating function act complementarily, it is possible to impart a switching function (on / off function) to CAC-OS or CAC-metal oxide. By separating the respective functions in CAC-OS or CAC-metal oxide, it is possible to maximize both functions.

[0266] Moreover, the CAC-OS or CAC-metal oxide has a conductive region and an insulating region. The conductive region has the above-mentioned conductive function, and the insulating region has the above-mentioned insulating function. In the material, the conductive region and the insulating region may be separated at the nanoparticle level. In addition, the conductive region and the insulating region may be unevenly distributed in the material. In addition, the conductive region may be observed to be connected in a cloud shape with a blurred periphery.

[0267] In addition, in the CAC-OS or CAC-metal oxide, the conductive regions and the insulating regions may each be dispersed in the material with a size of 0.5 nm to 10 nm, preferably 0.5 nm to 3 nm.

[0268] Also, the CAC-OS or CAC-metal oxide is composed of components having different band gaps. For example, the CAC-OS or CAC-metal oxide is composed of a component having a wide gap due to an insulating region and a component having a narrow gap due to a conductive region. In this configuration, when carriers are caused to flow, the carriers mainly flow in the component having the narrow gap. Also, the component having the narrow gap acts complementarily on the component having the wide gap, and carriers also flow in the component having the wide gap in conjunction with the component having the narrow gap. Therefore, when the above CAC-OS or CAC-metal oxide is used in the channel formation region of a transistor, a high current driving force, that is, a large on-current and a high field effect mobility can be obtained in the on-state of the transistor.

[0269] That is, CAC-OS or CAC-metal oxide can also be called a matrix composite or a metal matrix composite.

[0270] <Metal oxide structure> Oxide semiconductors are classified into single-crystal oxide semiconductors and non-single-crystal oxide semiconductors other than those. Examples of non-single-crystal oxide semiconductors include CAAC-OS, polycrystalline oxide semiconductors, nanocrystalline oxide semiconductors (nc-OS), amorphous-like oxide semiconductors (a-like OS), and amorphous oxide semiconductors.

[0271] In addition, when focusing on the crystal structure, oxide semiconductors may be classified differently from the above. Here, the classification of crystal structures in oxide semiconductors will be described with reference to Fig. 26A. Fig. 26A is a diagram for explaining the classification of crystal structures of oxide semiconductors, typically IGZO (metal oxide containing In, Ga, and Zn).

[0272] As shown in FIG. 26A, IGZO is broadly classified into Amorphous, Crystalline, and Crystal. Amorphous includes completely amorphous. Crystalline includes c-axis aligned crystalline (CAAC), nanocrystalline (nc), and cloud-aligned composite (CAC). Crystalline does not include single crystal, poly crystal, and completely amorphous. Crystal includes single crystal and poly crystal.

[0273] The structure in the bold frame shown in FIG. 26A is an intermediate state between Amorphous and Crystal, and belongs to a new boundary region (New crystalline phase). This structure is in the boundary region between Amorphous and Crystal. In other words, this structure can be said to be a structure that is completely different from Amorphous, which is energetically unstable, or Crystal.

[0274] The crystal structure of the film or substrate can be evaluated using an X-ray diffraction (XRD) image. Here, the XRD spectra of quartz glass and IGZO (also called crystalline IGZO) having a crystal structure classified as Crystalline are shown in Fig. 26B and Fig. 26C. Fig. 26B shows the XRD spectrum of quartz glass, and Fig. 26C shows the XRD spectrum of crystalline IGZO. The composition of the crystalline IGZO shown in Fig. 26C is in the vicinity of In:Ga:Zn=4:2:3 [atomic ratio]. The thickness of the crystalline IGZO shown in Fig. 26C is 500 nm.

[0275] As shown by the arrows in FIG. 26B, the shape of the peak in the XRD spectrum of silica glass is almost symmetric. On the other hand, as shown by the arrows in FIG. 26C, the shape of the peak in the XRD spectrum of crystalline IGZO is asymmetric. The asymmetric shape of the peak in the XRD spectrum clearly indicates the presence of crystals. In other words, if the shape of the peak in the XRD spectrum is not symmetric, it cannot be said to be amorphous. Note that FIG. 26C clearly shows the crystal phase (IGZO crystal phase) at or near 2θ=31°. It is presumed that the reason why the shape of the peak in the XRD spectrum is asymmetric is due to the crystal phase (microcrystals).

[0276] Specifically, the XRD spectrum of crystalline IGZO shown in FIG. 26C has a peak at or near 2θ=34°. Microcrystals have a peak at or near 2θ=31°. When an oxide semiconductor film is evaluated using an X-ray diffraction image, the width of the spectrum on the lower angle side is wider than the peak at or near 2θ=34°, as shown in FIG. 26C. This suggests that the oxide semiconductor film contains microcrystals having a peak at or near 2θ=31°.

[0277] The crystal structure of the film can be evaluated from the diffraction pattern (also called the nanobeam electron diffraction pattern) observed by nanobeam electron diffraction (NBED). Figure 26D shows the diffraction pattern of an IGZO film formed at room temperature on the substrate. The IGZO film shown in Figure 26D was formed by sputtering using an oxide target with an In:Ga:Zn=1:1:1 [atomic ratio]. In the nanobeam electron diffraction method, electron diffraction was performed with a probe diameter of 1 nm.

[0278] As shown in Figure 26D, a spot-like pattern, not a halo, is observed in the diffraction pattern of the IGZO film formed at room temperature. Therefore, it is presumed that the IGZO film formed at room temperature is in an intermediate state, neither crystalline nor amorphous, and it cannot be concluded that it is in an amorphous state.

[0279] CAAC-OS has a c-axis orientation and a distorted crystal structure in which multiple nanocrystals are connected in the ab-plane direction. The distortion refers to a portion where the lattice orientation changes between a region with a uniform lattice arrangement and a region with a different uniform lattice arrangement in the region where multiple nanocrystals are connected.

[0280] Nanocrystals are basically hexagonal, but are not limited to regular hexagonal shapes and may be non-regular hexagonal. In addition, the lattice arrangement of the distortion may be pentagonal, heptagonal, or other shapes. In the CAAC-OS, no clear grain boundary can be confirmed even near the distortion. In other words, it is found that the formation of grain boundaries is suppressed by the distortion of the lattice arrangement. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of dense arrangement of oxygen atoms in the ab-plane direction and the change in the bond distance between atoms due to the substitution of metal elements.

[0281] A crystal structure in which clear grain boundaries are observed is called polycrystal. The grain boundaries are likely to become recombination centers and capture carriers, causing a decrease in the on-current of a transistor or 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 the semiconductor layer of a transistor. In order to form a CAAC-OS, a structure containing Zn is preferable. For example, In-Zn oxide and In-Ga-Zn oxide are suitable because they can suppress the occurrence of grain boundaries more than In oxide.

[0282] CAAC-OS also tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium and oxygen (hereinafter, In layer) and a layer containing element M, zinc, and oxygen (hereinafter, (M, Zn) layer) are stacked. Note that indium and element M can be substituted for each other, and when element M in an (M, Zn) layer is substituted for indium, it can also be expressed as an (In, M, Zn) layer. When indium in an In layer is substituted for element M, it can also be expressed as an (In, M) layer.

[0283] The CAAC-OS is an oxide semiconductor with high crystallinity. On the other hand, since no clear crystal grain boundaries can be identified in the CAAC-OS, it can be said that a decrease in electron mobility due to the crystal grain boundaries is unlikely to occur. In addition, since the crystallinity of an oxide semiconductor can be decreased by the inclusion of impurities or the generation of defects, the CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, the physical properties of an oxide semiconductor having the CAAC-OS are stable. Therefore, an oxide semiconductor having the CAAC-OS is resistant to heat and has high reliability. In addition, the CAAC-OS is stable against high temperatures (so-called thermal budget) in the manufacturing process. Therefore, the use of the CAAC-OS in an OS transistor can increase the degree of freedom in the manufacturing process.

[0284] 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 addition, the nc-OS does not show regularity in the crystal orientation between different nanocrystals. Therefore, no orientation is seen 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.

[0285] 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 a pore or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and CAAC-OS.

[0286] Oxide semiconductors have a variety of structures and each structure 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, an nc-OS, and a CAAC-OS.

[0287] <Transistor Having Oxide Semiconductor> Next, the case where the oxide semiconductor is used for a transistor will be described.

[0288] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0289] In addition, it is preferable to use an oxide semiconductor with a low carrier concentration for the transistor. In order to reduce the carrier concentration of the oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as a high-purity intrinsic semiconductor or a substantially high-purity intrinsic semiconductor.

[0290] In addition, 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 might also be low.

[0291] In addition, charges trapped in the trap states of an oxide semiconductor take a long time to disappear and may behave as if they are 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.

[0292] Therefore, in order to stabilize the electrical characteristics of a transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. In order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in a nearby film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, silicon, and the like.

[0293] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0294] When an oxide semiconductor contains silicon or carbon, which is one of the group 14 elements, defect levels are formed in the oxide semiconductor. For this reason, the concentrations of silicon or carbon in the oxide semiconductor and those near the interface with the oxide semiconductor (concentrations obtained by secondary ion mass spectrometry (SIMS)) are calculated as 2×10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0295] 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, it is preferable to reduce the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor. Specifically, when the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor obtained by SIMS is reduced to 1×10 18atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 To the following:

[0296] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the oxide semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor is likely to have normally-on characteristics. Therefore, it is preferable that the nitrogen content in the oxide semiconductor is reduced as much as possible. For example, the nitrogen concentration in the oxide semiconductor is less than 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than or equal to 1×10 18 atoms / cm 3 Less than 5×10, more preferably 17 atoms / cm 3 The following applies.

[0297] Furthermore, hydrogen contained in an oxide semiconductor reacts with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. When hydrogen enters the oxygen vacancy, electrons serving as carriers may be generated. In addition, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons serving as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. For this reason, it is preferable to reduce hydrogen in the oxide semiconductor as much as possible. Specifically, when the hydrogen concentration in an oxide semiconductor measured by SIMS is 1×10 20 atoms / cm 3 Less than 1 x 10 19 atoms / cm 3 less than 5×10 18 atoms / cm 3 less than 1×10 18 atoms / cm 3 Less than.

[0298] When an oxide semiconductor in which impurities are sufficiently reduced is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0299] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification.

[0300] (Embodiment 7) In this embodiment, a light-emitting device that can be applied to a display device of one embodiment of the present invention and a light-emitting model of the light-emitting device will be described.

[0301] Fig. 27A to Fig. 27D are cross-sectional views for explaining the configuration of a light-emitting device, Fig. 27A being a cross-sectional view of a light-emitting device having a single structure, and Fig. 27B to Fig. 27D being cross-sectional views of a light-emitting device having a tandem structure.

[0302] <Single-structure light-emitting device> First, the light emitting device having a single structure shown in FIG. 27A will be described.

[0303] 27A includes an EL layer 1103 between a first electrode 1101 and a second electrode 1102. The EL layer 1103 also includes a hole injection layer 1111, a hole transport layer 1112, an emitting layer 1113, an electron transport layer 1114, and an electron injection layer 1115.

[0304] Materials that can be used in the light-emitting device of one embodiment of the present invention will be described below.

[0305] <First electrode and second electrode> The first electrode 1101 functions as either an anode or a cathode. The second electrode 1102 functions as either an anode or a cathode. In this embodiment, the first electrode 1101 is described as an anode, and the second electrode 1102 is described as a cathode. In this embodiment, the first electrode 1101 is reflective to visible light, and the second electrode 1102 is transparent to visible light. However, one embodiment of the present invention is not limited thereto, and the second electrode 1102 may be reflective to visible light and transparent to visible light. For example, when a light-emitting device having a microcavity structure is manufactured, an electrode having a reflectivity to visible light and an electrode having both reflectivity and transparency to visible light can be suitably used.

[0306] The first electrode 1101 and the second electrode 1102 may each be appropriately made of a metal, an alloy, an electrically conductive compound, or a mixture thereof. Specific examples include In-Sn oxide (also called ITO), In-Si-Sn oxide (also called ITSO), In-Zn oxide, and In-W-Zn oxide. Other examples include aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), and neodymium (Nd), as well as alloys containing these metals in appropriate combination. Other examples that can be used include elements belonging to Group 1 or 2 of the periodic table (e.g., lithium (Li), cesium (Cs), calcium (Ca), and strontium (Sr)) that are not listed above, rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing appropriate combinations of these, graphene, and the like.

[0307] Note that the first electrode 1101 and the second electrode 1102 can be formed by a sputtering method or a vacuum evaporation method.

[0308] <Hole injection layer> The hole injection layer 1111 preferably contains a first organic compound and a second organic compound. The first organic compound is a material that exhibits electron accepting properties toward the second organic compound. The second organic compound is a material that has a relatively deep highest occupied molecular orbital (HOMO) level of −5.7 eV or more and −5.4 eV or less. When the second organic compound has a relatively deep HOMO level, holes can be easily injected into the hole transport layer 1112.

[0309] The first organic compound may be an organic compound having an electron-withdrawing group (especially a halogen group such as a fluoro group or a cyano group), and among such materials, a material that exhibits electron-accepting properties toward the second organic compound may be appropriately selected. Examples of such organic compounds include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile, and the like. In particular, compounds in which an electron-withdrawing group is bonded to a condensed aromatic ring having multiple heteroatoms, such as HAT-CN, are thermally stable and preferred. Radialene derivatives having an electron-withdrawing group (especially a halogen group such as a fluoro group or a cyano group) [3] are preferred because they have a very high electron-accepting property, and specific examples thereof include α,α',α''-1,2,3-cyclopropane triylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropane triylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0310] The second organic compound is preferably an organic compound having hole transport properties, and preferably has at least one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, the second organic compound may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group.

[0311] Note that the second organic compound is preferably a material having an N,N-bis(4-biphenyl)amino group, since a light-emitting device with a long life can be manufactured.

[0312] <Hole transport layer> The hole transport layer 1112 preferably has a stacked structure of two or more layers. For example, the hole transport layer 1112 preferably has a first layer and a second layer on the first layer, the first layer preferably has a third organic compound, and the second layer preferably has a fourth organic compound.

[0313] The third organic compound and the fourth organic compound are preferably organic compounds having hole transport properties, and the third organic compound and the fourth organic compound can be made of the same material as the organic compound that can be used as the second organic compound.

[0314] It is preferable to select materials such that the HOMO level of the third organic compound is deeper than that of the second organic compound, and the difference between the HOMO levels is 0.2 eV or less. It is more preferable that the second organic compound and the third organic compound are the same material.

[0315] In addition, it is preferable that the HOMO level of the fourth organic compound is deeper than that of the third organic compound. Furthermore, it is preferable to select each material so that the difference between the HOMO levels is 0.2 eV or less. When the HOMO levels of the second organic compound to the fourth organic compound have the above-mentioned relationship, holes are smoothly injected into each layer, and an increase in driving voltage and a state of insufficient holes in the light-emitting layer can be prevented.

[0316] Each of the second organic compound to the fourth organic compound preferably has a hole-transporting skeleton. As the hole-transporting skeleton, a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton are preferable because the HOMO level of these organic compounds is not too shallow. In addition, it is preferable that the hole-transporting skeleton is common to the materials of adjacent layers (for example, the second organic compound and the third organic compound, or the third organic compound and the fourth organic compound) because this facilitates the injection of holes. In particular, the hole-transporting skeleton is preferably a dibenzofuran skeleton.

[0317] In addition, it is preferable that the materials contained in adjacent layers (for example, the second organic compound and the third organic compound, or the third organic compound and the fourth organic compound) are the same material, since this makes the injection of holes smoother. In particular, it is preferable that the second organic compound and the third organic compound are the same material.

[0318] <Light-emitting layer> The light-emitting layer 1113 preferably contains a fifth organic compound and a sixth organic compound. The fifth organic compound is a material having a light-emitting center material (also referred to as a light-emitting material or a guest material), and the sixth organic compound is a host material for dispersing the fifth organic compound. Note that the sixth organic compound may be composed of one or more kinds of organic compounds (for example, two kinds of host material and assist material). As the one or more kinds of organic compounds, one or both of a hole-transporting material and an electron-transporting material described in this embodiment can be used. In addition, as the one or more kinds of organic compounds, a bipolar material may be used.

[0319] The light-emitting layer 1113 may have a single-layer structure or a laminated structure of two or more layers. In the case of a laminated structure of two or more layers, different light-emitting materials may be included in the layers.

[0320] The fifth organic compound is a light-emitting material, and the light-emitting color of the light-emitting material may be blue, purple, blue-purple, green, yellow-green, yellow, orange, red, etc. In one embodiment of the present invention, when the light-emitting layer 1113 contains a fluorescent material, it is particularly preferable that the light-emitting color be blue.

[0321] The light-emitting material that can be used for the light-emitting layer 1113 is not particularly limited, and may be a light-emitting material (fluorescent material) that converts singlet excitation energy into light emission in the visible light or near-infrared light region, or a light-emitting material (phosphorescent material or thermally activated delayed fluorescence (TADF) material) that converts triplet excitation energy into light emission in the visible light or near-infrared light region.

[0322] <Fluorescent materials> Examples of luminescent materials that convert singlet excitation energy into luminescence include fluorescent luminescent materials, such as pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, naphthalene derivatives, etc. Pyrene derivatives are particularly preferred because of their high luminescence quantum yield. Specific examples of pyrene derivatives include N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(dibenzofuran-2-yl)-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6FrAPrn), N,N'-bis(dibenzothiophene-2-yl)-N, N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-6-amine] (abbreviation: 1,6BnfAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-02), N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), etc.

[0323] In addition, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)phenyl]- N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), 4-(10-phenyl-9-anthryl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), 4-(10-phenyl-9-anthryl)-4' -(9-Phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), 4-[4-(10-phenyl-9-anthryl)phenyl]-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPBA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenyl) N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), and the like can be used.

[0324] Examples of light-emitting materials that convert triplet excitation energy into light include phosphorescent materials and TADF materials that exhibit thermally activated delayed fluorescence. Details of TADF materials will be described later.

[0325] <Phosphorescent materials> Examples of phosphorescent materials include organometallic complexes (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine 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.

[0326] Examples of phosphorescent materials that exhibit blue or green light and have an emission spectrum with a peak wavelength of 450 nm or more and 570 nm or less include the following materials.

[0327] For example, tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl )-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPr5btz)3]), and other organometallic complexes having a 4H-triazole skeleton, such as tris[3-methyl-1-( organometallic complexes with a 1H-triazole skeleton, such as fac-tris[1-(2,6-diisopropylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]); organometallic complexes with an imidazole skeleton, such as tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}Iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’] Examples include organometallic complexes with phenylpyridine derivatives having electron-withdrawing groups as ligands, such as iridium(III) acetylacetonate (abbreviation: FIr(acac)).

[0328] Examples of phosphorescent materials that exhibit green or yellow color and have an emission spectrum with a peak wavelength of 495 nm or more and 590 nm or less include the following materials.

[0329] For example, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm) 2(acac)]), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: [Ir(dmppm-dmp)2(acac)]), and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]). iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinate)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinate)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]); tris(2-phenylpyrazinate-N,C 2’ ) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’)iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’ Organometallic iridium complexes with pyridine skeletons such as iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-(4-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(4dppy)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC], and bis(2,4-diphenyl-1,3-oxazolato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(dpo)2(acac)]), bis{2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2’}Iridium(III) acetylacetonate (abbreviation: [Ir(p-PF-ph)2(acac)]), bis(2-phenylbenzothiazolato-N,C 2’ ) iridium(III) acetylacetonate (abbreviation: [Ir(bt)2(acac)]), as well as rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]).

[0330] Examples of phosphorescent materials that exhibit yellow or red light and have an emission spectrum with a peak wavelength of 570 nm or more and 750 nm or less include the following materials.

[0331] For example, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) Organometallic complexes with pyrimidine skeletons such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), and bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl-κC}(2,6-dimethyl-3,5-heptanedionato-κN)phenyl-κC). 2 O,O')iridium(III) (abbreviation: [Ir(dmdppr-P)2(dibm)]), bis{4,6-dimethyl-2-[5-(4-cyano-2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ 2 O,O')iridium(III) (abbreviation: [Ir(dmdppr-dmCP)2(dpm)]), (acetylacetonato)bis[2-methyl-3-phenylquinoxalinato-N,C 2’ ]Iridium(III) (abbreviation: [Ir(mpq)2(acac)]), (acetylacetonato)bis(2,3-diphenylquinoxalinato-N,C 2’)iridium(III) (abbreviation: [Ir(dpq)2(acac)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), bis{4,6-dimethyl-2-[5-(5-cyano-2-methylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ2O,O')iridium(III) (abbreviation: [Ir(dmdppr-m5CP)2(dpm)]), and other organometallic complexes with pyrazine skeletons, such as tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), bis[4,6-dimethyl-2-(2-quinolinyl-κN)phenyl-κC](2,4-pentanedionato-κ 2 Examples of such complexes include organometallic complexes with a pyridine skeleton, such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: [PtOEP]), and rare earth metal complexes, such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]).

[0332] As the organic compound (host material, assist material, etc.) used in the light-emitting layer, one or more materials having an energy gap larger than the energy gap of the light-emitting material can be selected and used.

[0333] As an organic compound (host material) used in combination with a fluorescent light-emitting material, it is preferable to use an organic compound having a high energy level in a singlet excited state and a low energy level in a triplet excited state.

[0334] Although some of the examples overlap with the above specific examples, specific examples of organic compounds are shown below from the viewpoint of preferable combinations with light-emitting materials (fluorescent light-emitting materials, phosphorescent light-emitting materials).

[0335] Examples of organic compounds (host materials) that can be used in combination with fluorescent materials include condensed polycyclic aromatic compounds such as anthracene derivatives, tetracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives.

[0336] Specific examples of organic compounds (host materials) used in combination with fluorescent materials include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl- 9-Anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), YGAPA, PCAPA, N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene , N,N,N',N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9 -phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)-biphenyl-4'-yl}-anthracene (abbreviation: FLPPA), 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-bianthryl (abbreviation: BANT), 9,9'-(stilbene-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-tri(1-pyrenyl)benzene (abbreviation: TPB3), 5,12-diphenyltetracene, 5,12-bis(biphenyl-2-yl)tetracene, etc.

[0337] As an organic compound (host material) used in combination with a phosphorescent material, an organic compound having a triplet excitation energy greater than the triplet excitation energy (energy difference between the ground state and the triplet excited state) of the light-emitting material may be selected.

[0338] When multiple organic compounds (e.g., a first host material and a second host material (or assist material)) are used in combination with an emitting material to form an exciplex, it is preferable to use these multiple organic compounds in combination with a phosphorescent emitting material (particularly an organometallic complex).

[0339] With this structure, light emission using ExTET (Exciplex-Triplet Energy Transfer), which is an energy transfer from an exciplex to a light-emitting material, can be efficiently obtained. As a combination of a plurality of organic compounds, it is preferable to use a compound that easily forms an exciplex, and it is particularly preferable to combine a compound that easily receives holes (hole transporting material) with a compound that easily receives electrons (electron transporting material). By selecting a combination that forms an exciplex that exhibits light emission that overlaps with the wavelength of the absorption band on the lowest energy side of the light-emitting material, energy transfer becomes smooth, and light emission can be efficiently obtained. As specific examples of the hole transporting material and the electron transporting material, the materials shown in this embodiment can be used. With this structure, high efficiency, low voltage, and long life of the light-emitting device can be simultaneously achieved.

[0340] As a combination of materials that form an exciplex, it is preferable that the HOMO level of the hole transporting material is equal to or higher than the HOMO level of the electron transporting material. It is preferable that the LUMO level (lowest unoccupied molecular orbital level) of the hole transporting material is equal to or higher than the LUMO level of the electron transporting material. The LUMO level and HOMO level of the material can be derived from the electrochemical properties (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV) measurement.

[0341] The formation of an exciplex can be confirmed, for example, by comparing the emission spectrum of a hole transport material, the emission spectrum of an electron transport material, and the emission spectrum of a mixed film obtained by mixing these materials, and observing the phenomenon that the emission spectrum of the mixed film shifts to a longer wavelength than the emission spectrum of each material (or has a new peak on the longer wavelength side). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a hole transport material, the transient PL of an electron transport material, and the transient PL of a mixed film obtained by mixing these materials, and observing the difference in transient response, such as the transient PL lifetime of the mixed film having a longer lifetime component than the transient PL lifetime of each material, or the proportion of delayed components becoming larger. In addition, the above-mentioned transient PL may be read as transient electroluminescence (EL). In other words, the formation of an exciplex can also be confirmed by comparing the transient EL of a hole transport material, the transient EL of a material having electron transport properties, and the transient EL of a mixed film obtained by mixing these materials, and observing the difference in transient response.

[0342] Examples of organic compounds that can be used in combination with phosphorescent materials include aromatic amines (compounds having an aromatic amine skeleton), carbazole derivatives (compounds having a carbazole skeleton), dibenzothiophene derivatives (thiophene derivatives), dibenzofuran derivatives (furan derivatives), zinc- or aluminum-based metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, and phenanthroline derivatives.

[0343] Specific examples of aromatic amines, carbazole derivatives, dibenzothiophene derivatives, and dibenzofuran derivatives, which are organic compounds having high hole transport properties, include the following materials.

[0344] Examples of the carbazole derivative include bicarbazole derivatives (for example, 3,3'-bicarbazole derivatives) and aromatic amines having a carbazolyl group.

[0345] Specific examples of bicarbazole derivatives (e.g., 3,3'-bicarbazole derivatives) include 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-bis(1,1'-biphenyl-4-yl)-3,3'-bi-9H-carbazole, 9,9'-bis(1,1'-biphenyl-3-yl)-3,3'-bi-9H-carbazole, 9-(1,1'-biphenyl-3-yl)-9'-(1,1'-biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), and 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP).

[0346] Specific examples of aromatic amines having a carbazolyl group include PCBA1BP, N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), PCBBiF, PCBBi1BP, PCBANB, PCBNBB, 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: P CA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), PCBASF, 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), PCBASF, 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole N-(1-naphthyl)amino)-9-phenylcarbazole (abbreviation: PCzTPN2), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA) and the like.

[0347] In addition to the above, examples of carbazole derivatives include 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), PCPN, 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), CzPA, and the like.

[0348] Specific examples of thiophene derivatives (compounds having a thiophene skeleton) and furan derivatives (compounds having a furan skeleton) include compounds having a thiophene skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II).

[0349] Specific examples of aromatic amines include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), BPAFLP, mBPAFLP, N-(9,9-dimethyl-9H-fluorene -2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 4,4',4''-Tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), 4,4',4''-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), N,N'-di(p-to Examples of such amines include 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0350] As organic compounds with high hole-transporting properties, polymer compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used.

[0351] Specific examples of zinc- or aluminum-based metal complexes, which are organic compounds with high electron transport properties, include metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq).

[0352] In addition, metal complexes having oxazole or thiazole ligands, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), can also be used.

[0353] Specific examples of organic compounds with high electron transport properties, such as oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, and phenanthroline derivatives, include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-8), and 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-9). 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDB q-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,Examples include quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzothiophene[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II).

[0354] Specific examples of heterocyclic compounds having a diazine skeleton, a heterocyclic compound having a triazine skeleton, and a heterocyclic compound having a pyridine skeleton, which are organic compounds with high electron transport properties, include 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), and the like.

[0355] As the organic compound with high electron transport properties, high molecular compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can also be used.

[0356] <TADF material> A TADF material is a material that has a small difference between the S1 level (energy level of the singlet excited state) and the T1 level (energy level of the triplet excited state), and has the function of converting energy from triplet excitation energy to singlet excitation energy by reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy by a small amount of thermal energy (reverse intersystem crossing), and the singlet excited state can be efficiently generated. In addition, triplet excitation energy can be converted into light emission. Conditions for efficiently obtaining thermally activated delayed fluorescence include an energy difference between the S1 level and the T1 level of 0 eV or more and 0.2 eV or less, preferably 0 eV or more and 0.1 eV or less. In addition, delayed fluorescence in a TADF material refers to light emission that has a spectrum similar to that of normal fluorescence, but has a significantly long life. The life is about 10 -6 seconds or more, preferably 10 -3 More than seconds.

[0357] The exciplex, which forms an excited state with two types of materials, has an extremely small difference between the S1 and T1 levels and functions as a TADF material that can convert triplet excitation energy into singlet excitation energy.

[0358] As an index of the T1 level, a phosphorescence spectrum observed at low temperatures (for example, 77 K to 10 K) may be used. For a TADF material, when a tangent is drawn at the base of the short wavelength side of the fluorescence spectrum, and the energy of the wavelength of the extrapolated line is taken as the S1 level, and a tangent is drawn at the base of the short wavelength side of the phosphorescence spectrum, and the energy of the wavelength of the extrapolated line is taken as the T1 level, the difference between S1 and T1 is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0359] Examples of TADF materials include fullerene and its derivatives, acridine derivatives such as proflavine, eosin, etc. Also included are metal-containing porphyrins including magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), etc. Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complex (abbreviation: SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (abbreviation: SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviation: SnF2(OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2OEP).

[0360] Other examples include 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), PCCzPTzn, 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), and bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DM AC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), 4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl) Heterocyclic compounds having a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, such as 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzPBfpm) and 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), can be used.

[0361] The heterocyclic compound has a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred.Among the 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 have good reliability.In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton and benzothienopyrazine skeleton are preferred because they have high electron acceptability and good reliability.

[0362] Among the skeletons having a π-electron-rich heteroaromatic ring, it is preferable to have at least one of the acridine skeleton, the phenoxazine skeleton, the phenothiazine skeleton, the furan skeleton, the thiophene skeleton, and the pyrrole skeleton, since they are stable and reliable. As the furan skeleton, the dibenzofuran skeleton is preferable, and as the thiophene skeleton, the dibenzothiophene skeleton is preferable. As the pyrrole skeleton, the indole skeleton, the carbazole skeleton, the indolocarbazole skeleton, the bicarbazole skeleton, and the 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferable.

[0363] In addition, a material in which a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring are directly bonded is particularly preferable because the electron donating property of the π-electron rich heteroaromatic ring and the electron accepting property of the π-electron deficient heteroaromatic ring are both strong, and the energy difference between the S1 level and the T1 level is small, so that thermally activated delayed fluorescence can be efficiently obtained. In addition, an aromatic ring to which an electron withdrawing group such as a cyano group is bonded may be used instead of the π-electron deficient heteroaromatic ring. In addition, an aromatic amine skeleton, a phenazine skeleton, or the like can be used as the π-electron rich skeleton. In addition, 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 or a heteroaromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, or the like can be used as the π-electron deficient skeleton.

[0364] In this manner, at least one of a π-electron deficient skeleton and a π-electron rich skeleton can be used in place of at least one of a π-electron deficient heteroaromatic ring and a π-electron rich heteroaromatic ring.

[0365] In addition, when a TADF material is used, it can be used in combination with other organic compounds. In particular, it can be combined with the above-mentioned host material, hole transport material, and electron transport material. When a TADF material is used, the S1 level of the host material is preferably higher than the S1 level of the TADF material. In addition, the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0366] Also, a TADF material may be used as a host material, and a fluorescent material may be used as a guest material. When a TADF material is used as a host material, triplet excitation energy generated in the TADF material is converted to singlet excitation energy by reverse intersystem crossing, and the energy is further transferred to the light-emitting material, thereby improving the light-emitting efficiency of the light-emitting device. At this time, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor. Therefore, using a TADF material as a host material is very effective when using a fluorescent material as a guest material. At this time, in order to obtain high light-emitting efficiency, the S1 level of the TADF material is preferably higher than the S1 level of the fluorescent material. Also, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent material. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent material.

[0367] It is also preferable to use a TADF material that emits light that overlaps with the wavelength of the lowest energy absorption band of the fluorescent material, since this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient emission.

[0368] In addition, in order to efficiently generate singlet excitation energy from triplet excitation energy by reverse intersystem crossing, it is preferable that carrier recombination occurs in the TADF material. In addition, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent material. For this purpose, it is preferable that the fluorescent material has a protective group around the luminophore (skeleton causing light emission) of the fluorescent material. As the protective group, a substituent having no π bond is preferable, and a saturated hydrocarbon is preferable, specifically, an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms are mentioned, and it is more preferable that there are a plurality of protective groups. Since a substituent having no π bond has poor function of transporting carriers, the distance between the TADF material and the luminophore of the fluorescent material can be increased without affecting carrier transport or carrier recombination. Here, the luminophore refers to an atomic group (skeleton) causing light emission in the fluorescent material. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a condensed aromatic ring or a condensed heteroaromatic ring. Examples of the condensed aromatic ring or the condensed heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, and a phenothiazine skeleton. In particular, fluorescent materials having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton are preferred because they have a high fluorescence quantum yield.

[0369] The above TADF material may be used as a host material for the light-emitting layer.

[0370] <Electron transport layer> The electron transport layer 1114 is provided in contact with the light-emitting layer 1113. The electron transport layer 1114 preferably contains a seventh organic compound having an electron transport property and a HOMO level of −6.0 eV or higher. The seventh organic compound preferably contains an anthracene skeleton. The electron transport layer 1114 may further contain an eighth organic compound in addition to the seventh organic compound. The eighth organic compound preferably contains an organic complex of an alkali metal or an alkaline earth metal. That is, the electron transport layer 1114 may be formed of only the seventh organic compound, or may be formed of a plurality of organic compounds including the seventh organic compound and the eighth organic compound.

[0371] It is more preferable that the seventh organic compound contains an anthracene skeleton and a heterocyclic skeleton. The heterocyclic skeleton is preferably a nitrogen-containing five-membered ring skeleton. The nitrogen-containing five-membered ring skeleton is particularly preferably a pyrazole ring, an imidazole ring, an oxazole ring, or a thiazole ring having two heteroatoms in the ring.

[0372] In addition, as a material having electron transport properties that can be used as the seventh organic compound, a material having electron transport properties that can be used as the host material or a material that can be used as the host material of the fluorescent light-emitting material can be used.

[0373] As the organic complex of the alkali metal or alkaline earth metal, an organic complex of lithium is preferable, and in particular, 8-quinolinolato-lithium (abbreviation: Liq) is preferable.

[0374] The material constituting the electron transport layer 1114 has an electron mobility of 1×10 -7 cm 2 / Vs or more 5×10 -5 cm 2 It is preferable that the value is equal to or less than / Vs.

[0375] It is also preferable that the electron mobility of the material constituting the electron transport layer 1114 at a square root of the electric field strength [V / cm] of 600 is smaller than the electron mobility of the sixth organic compound or the material constituting the light-emitting layer 1113 at a square root of the electric field strength [V / cm] of 600. By reducing the electron transportability in the electron transport layer, the amount of electrons injected into the light-emitting layer can be controlled, and the light-emitting layer can be prevented from becoming in an electron excess state.

[0376] <Electron injection layer> The electron injection layer 1115 is a layer that increases the efficiency of injection of electrons from the second electrode 1102. It is preferable that the difference between the work function value of the material of the second electrode 1102 and the LUMO level value of the material used for the electron injection layer 1115 is small (within 0.5 eV).

[0377] The electron injection layer 1115 may include any of the following: lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), lithium oxide (LiO x ), alkaline metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used. Rare earth metal compounds such as erbium fluoride (ErF3) can also be used. Electrides may also be used in the electron injection layer. Examples of electrides include materials in which electrons are highly concentrated in a mixed oxide of calcium and aluminum. The materials constituting the electron transport layer described above can also be used.

[0378] In addition, a composite material containing an electron transporting material and a donor material (electron donor material) may be used for the electron injection layer 1115. Such a composite material has excellent electron injection and transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons, and specifically, for example, the above-mentioned electron transporting material (metal complex, heteroaromatic compound, etc.) can be used. As the electron donor, any material that exhibits electron donating properties to the organic compound may be used. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferable, and examples thereof include lithium, cesium, magnesium, calcium, erbium, and ytterbium. In addition, alkali metal oxides and alkaline earth metal oxides are preferable, and examples thereof include lithium oxide, calcium oxide, and barium oxide. In addition, a Lewis base such as magnesium oxide can also be used. In addition, an organic compound such as tetrathiafulvalene (abbreviation: TTF) can also be used.

[0379] In addition, a vacuum process such as a deposition method, or a solution process such as a spin coating method or an inkjet method can be used to manufacture the light-emitting device of one embodiment of the present invention. When a deposition method is used, a physical deposition method (PVD method) such as a sputtering method, an ion plating method, an ion beam deposition method, a molecular beam deposition method, or a vacuum deposition method, or a chemical deposition method (CVD method) can be used. In particular, the functional layers (hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer) included in the EL layer can be formed by a deposition method (vacuum deposition method, etc.), a coating method (dip coating method, die coating method, bar coating method, spin coating method, spray coating method, etc.), a printing method (inkjet method, screen (screen printing) method, offset (lithographic printing) method, flexo (relief printing) method, gravure method, microcontact method, etc.), or the like.

[0380] In addition, the materials of each functional layer constituting the light-emitting device are not limited to the above-mentioned materials. For example, the materials of the functional layers may be polymer compounds (oligomers, dendrimers, polymers, etc.), medium molecular compounds (compounds in the intermediate range between low molecular weight and high molecular weight: molecular weight 400 to 4000), inorganic compounds (quantum dot materials, etc.), etc. In addition, the quantum dot materials may be colloidal quantum dot materials, alloy type quantum dot materials, core-shell type quantum dot materials, core type quantum dot materials, etc.

[0381] Note that the light-emitting device of one embodiment of the present invention may have a functional layer other than the layers described above. As the functional layer, for example, various layers such as a carrier block layer and an exciton block layer can be used.

[0382] <Emission model for light-emitting devices> Next, an emission model of the light-emitting device of one embodiment of the present invention will be described with reference to FIGS. 28A to 28C. FIG.

[0383] 28A to 28C are schematic diagrams illustrating a light emission model in a light emitting device. In addition, in Fig. 28A to Fig. 28C, a light emitting region in the light emitting device is represented as light emitting region 1120.

[0384] Fig. 28A is a light-emitting model showing a light-emitting region 1120 in an electron-abundant state of a light-emitting layer 1113. Fig. 28B and Fig. 28C are light-emitting models showing a light-emitting region 1120 in a light-emitting device according to one embodiment of the present invention.

[0385] As shown in Fig. 28A, when light-emitting layer 1113 becomes in an electron excess state, light-emitting region 1120 is formed in a localized region in light-emitting layer 1113. In other words, the width of light-emitting region 1120 is narrow. Therefore, recombination of electrons and holes is concentrated in the localized region of light-emitting layer 1113, accelerating degradation. Furthermore, in light-emitting layer 1113, electrons that cannot recombine pass through light-emitting layer 1113, which may reduce the lifetime or luminous efficiency.

[0386] 28B and 28C , in the light-emitting device of one embodiment of the present invention, the width of the light-emitting region 1120 in the light-emitting layer 1113 can be increased by decreasing the electron transport property in the electron-transport layer 1114. By increasing the width of the light-emitting region 1120, the recombination region of electrons and holes in the light-emitting layer 1113 can be dispersed. Thus, a light-emitting device with a long lifetime and high light-emitting efficiency can be provided.

[0387] In addition, in the light-emitting device of one embodiment of the present invention, a degradation curve of luminance obtained by a driving test under a constant current density condition may have a maximum value. In other words, the light-emitting device of one embodiment of the present invention may exhibit a behavior in which the luminance increases with time. This behavior can offset rapid deterioration (so-called initial deterioration) at the beginning of driving. Therefore, a light-emitting device with small initial deterioration and very good driving life can be provided.

[0388] Note that when the degradation curve having the maximum value is differentiated, there is a portion where the value is 0. Therefore, a light-emitting device having a portion where the differential of the degradation curve is 0 can be rephrased as a light-emitting device according to one embodiment of the present invention.

[0389] Here, normalized luminance over time in the light-emitting device of one embodiment of the present invention and the comparative light-emitting device will be described with reference to FIG. 28D.

[0390] In FIG. 28D, the thick solid line is a deterioration curve of normalized luminance of the light-emitting device according to one embodiment of the present invention, and the thick dashed line is a deterioration curve of normalized luminance of the comparative light-emitting device.

[0391] 28D, the light-emitting device according to one embodiment of the present invention and the comparative light-emitting device have different slopes of degradation curves of normalized luminance. Specifically, the slope θ2 of the degradation curve of the light-emitting device according to one embodiment of the present invention is smaller than the slope θ1 of the degradation curve of the comparative light-emitting device.

[0392] As shown in Fig. 28D, the light-emitting device according to one embodiment of the present invention may have a shape having a maximum value in a luminance deterioration curve obtained by a drive test under a constant current density condition. That is, the deterioration curve of the light-emitting device according to one embodiment of the present invention may have a shape having a portion where the luminance increases with time. A light-emitting device exhibiting such deterioration behavior can offset the rapid deterioration at the beginning of driving, so-called initial deterioration, with the increase in luminance, and can be a light-emitting device with small initial deterioration and very long driving life.

[0393] In the light-emitting device of one embodiment of the present invention, the light-emitting region 1120 formed in the light-emitting layer 1113 may extend to the electron-transport layer 1114 side in the initial driving period as shown in FIG. 28B.

[0394] That is, in the light-emitting device according to one embodiment of the present invention, the hole injection barrier is small at the beginning of operation, and the electron transporting property of the electron transporting layer 1114 is relatively low, so that the light-emitting region 1120 (i.e., the recombination region) is formed in a state close to the electron transporting layer 1114 side. In addition, since the HOMO level of the seventh organic compound contained in the electron transporting layer 1114 is relatively high at -6.0 eV or more, some of the holes reach the electron transporting layer 1114, and recombination also occurs in the electron transporting layer 1114, forming a non-light-emitting recombination region. Note that this phenomenon may also occur when the difference in the HOMO levels of the sixth organic compound and the seventh organic compound is within 0.2 eV.

[0395] Furthermore, in a light-emitting device according to one embodiment of the present invention, the carrier balance changes over time as the device is driven, and the light-emitting region 1120 (recombination region) moves toward the hole-transport layer 1112 and becomes located within the light-emitting layer 1113, as shown in FIG. 28C.

[0396] 28B and 28C, in the light-emitting device according to one embodiment of the present invention, by moving the light-emitting region 1120 in the light-emitting layer 1113 with the passage of driving time, the energy of recombined carriers can be effectively contributed to light emission, and the luminance can increase compared to the initial driving period. This increase in luminance offsets the rapid decrease in luminance that occurs in the initial driving period of the light-emitting device, that is, the initial deterioration, and thus a light-emitting device with small initial deterioration and long driving life can be provided. Note that in this specification and the like, the above-mentioned light-emitting device may be referred to as a Recombination-Site Tailoring Injection structure (ReSTI structure).

[0397] In addition, in the light-emitting device of one embodiment of the present invention, the electron-transport layer 1114 preferably has, in the thickness direction, a portion where the mixture ratio of the electron-transport material and the organometallic complex of an alkali metal or an alkaline earth metal is different, or a portion where the concentration of the organometallic complex of an alkali metal or an alkaline earth metal is different.

[0398] The concentration of the organometallic complex of an alkali metal or alkaline earth metal in the electron transport layer 1114 can be estimated from the amount of atoms or molecules detected by time-of-flight secondary ion mass spectrometry (ToF-SIMS).

[0399] The content of the organometallic complex in the electron transport layer 1114 is preferably lower on the second electrode 1102 side than on the first electrode 1101 side. In other words, the electron transport layer 1114 is preferably formed so that the concentration of the organometallic complex increases from the second electrode 1102 side toward the first electrode 1101 side. That is, the electron transport layer 1114 has a portion on the light-emitting layer 1113 side where the electron transport material is present in a smaller amount than a portion on the light-emitting layer 1113 side where the electron transport material is present in a larger amount. In other words, the electron transport layer 1114 can be said to have a structure having a portion on the light-emitting layer 1113 side where the organometallic complex is present in a larger amount than a portion on the light-emitting layer 1113 side where the organometallic complex is present in a smaller amount.

[0400] The electron mobility in the area where the amount of electron transport material is high (the area where the amount of organometallic complex is low) is 1×10 at a square root of the electric field strength [V / cm] of 600. -7 cm 2 / Vs or more 5×10 -5 cm 2 It is preferable that the value is equal to or less than / Vs.

[0401] For example, the content of the organometallic complex in the electron transport layer 1114, i.e., the concentration of the organometallic complex in the electron transport layer 1114, can be as shown in Figures 29A to 29D. Figures 29A and 29B show a case where there is no clear boundary in the electron transport layer 1114, and Figures 29C and 29D show a case where there is a clear boundary in the electron transport layer 1114.

[0402] When there is no clear boundary in the electron transport layer 1114, the concentrations of the electron transport material and the organometallic complex change continuously as shown in FIG. 29A and FIG. 29B. When there is a clear boundary in the electron transport layer 1114, the concentrations of the electron transport material and the organometallic complex change stepwise as shown in FIG. 29C and FIG. 29D. Note that the stepwise change suggests that the electron transport layer 1114 is stacked with multiple layers. For example, FIG. 29C shows a case where the electron transport layer 1114 has a two-layer stacked structure, and FIG. 29D shows a case where the electron transport layer 1114 has a three-layer stacked structure. Note that in FIG. 29C and FIG. 29D, the dashed lines show the boundary regions of multiple layers.

[0403] A change in the carrier balance in the light-emitting device of one embodiment of the present invention is considered to be brought about by a change in the electron mobility of the electron-transport layer 1114. In the light-emitting device of one embodiment of the present invention, a concentration difference of an organometallic complex of an alkali metal or an alkaline earth metal exists in the electron-transport layer 1114. The electron-transport layer 1114 has a region where the concentration of the organometallic complex is high between a region where the concentration of the organometallic complex is low and the light-emitting layer 1113. That is, the region where the concentration of the organometallic complex is low is located closer to the second electrode 1102 than the region where the concentration of the organometallic complex is high.

[0404] The light-emitting device according to one embodiment of the present invention having the above-described structure has a very long lifetime. In particular, when the initial luminance is set to 100%, the time required for the luminance to reach 95% (also referred to as LT95) can be made extremely long.

[0405] <Light-emitting device with tandem structure> Next, a light emitting device having a tandem structure shown in FIGS. 27B to 27D will be described.

[0406] The light-emitting device shown in Figures 27B to 27D has multiple light-emitting units between a first electrode 1101 and a second electrode 1102. As shown in Figures 27B to 27D, it is preferable to provide a charge generation layer 1109 between two light-emitting units.

[0407] Each of light-emitting unit 1123(1) and light-emitting unit 1123(2) includes hole injection layer 1111, hole transport layer 1112, light-emitting layer 1113, electron transport layer 1114, electron injection layer 1115, and the like, as shown in FIG. 27A.

[0408] <Charge generation layer> Charge generation layer 1109 has a function of injecting electrons into one of light-emitting unit 1123(1) and light-emitting unit 1123(2) and injecting holes into the other when a voltage is applied between first electrode 1101 and second electrode 1102. Therefore, in Fig. 27B, when a voltage is applied to first electrode 1101 so that the potential is higher than that of second electrode 1102, electrons are injected from charge generation layer 1109 into light-emitting unit 1123(1) and holes are injected into light-emitting unit 1123(2).

[0409] From the viewpoint of light extraction efficiency, the charge generation layer 1109 preferably transmits visible light (specifically, the visible light transmittance of the charge generation layer 1109 is 40% or more). The charge generation layer 1109 functions even if it has a lower conductivity than the first electrode 1101 and the second electrode 1102.

[0410] The EL layer 1103 shown in Fig. 27C has a charge generation layer 1109 between the first light-emitting unit 1123(1) and the second light-emitting unit 1123(2), and has a charge generation layer 1109 between the second light-emitting unit 1123(2) and the third light-emitting unit 1123(3). The light-emitting element shown in Fig. 27D has m light-emitting units (m is a natural number of 2 or more) and n light-emitting units (n is a natural number of m or more), and has a charge generation layer 1109 between each light-emitting unit. The third light-emitting unit 1123(3), the light-emitting unit 1123(m), and the light-emitting unit 1123(n) each have a hole injection layer 1111, a hole transport layer 1112, a light-emitting layer 1113, an electron transport layer 1114, an electron injection layer 1115, and the like, as shown in Fig. 27A. The light emitting units may have the same configuration or different configurations.

[0411] Here, the behavior of electrons and holes in the charge generation layer 1109 provided between the light-emitting unit 1123(m) and the light-emitting unit 1123(m+1) will be described. When a voltage higher than the threshold voltage of the light-emitting device is applied between the first electrode 1101 and the second electrode 1102, holes and electrons are generated in the charge generation layer 1109, the holes move to the light-emitting unit 1123(m+1) provided on the second electrode 1102 side, and the electrons move to the light-emitting unit 1123(m) provided on the first electrode 1101 side. The holes injected into the light-emitting unit 1123(m+1) are recombined with the electrons injected from the second electrode 1102 side, and the light-emitting material included in the light-emitting unit 1123(m+1) emits light. The electrons injected into the light-emitting unit 1123(m) are recombined with the holes injected from the first electrode 1101 side, and the light-emitting material included in the light-emitting unit 1123(m) emits light. Therefore, holes and electrons generated in the charge generating layer 1109 emit light in different light emitting units.

[0412] In addition, when the light-emitting units are provided in contact with each other to form the same structure as the charge generation layer 1109 between them, the light-emitting units can be provided in contact with each other without the charge generation layer 1109. For example, when a charge generation region is formed on one surface of the light-emitting unit, the light-emitting unit can be provided in contact with that surface.

[0413] Tandem-structure light-emitting devices have higher current efficiency and require less current to emit light with the same brightness compared to single-structure light-emitting devices, which can increase the life and reliability of the light-emitting devices.

[0414] The light-emitting units may have the same light-emitting material or different light-emitting materials. The light-emitting material of each light-emitting unit is not particularly limited. In order to improve reliability, it is preferable that a plurality of fluorescent light-emitting units are laminated. For example, in the case where the same light-emitting material is used, a highly reliable light-emitting device can be provided by combining a blue fluorescent light-emitting unit and a blue fluorescent light-emitting unit. In addition, one or more fluorescent light-emitting units and phosphorescent light-emitting units may be laminated. For example, a light-emitting device capable of emitting white light can be provided by combining a blue fluorescent light-emitting unit, a red phosphorescent light-emitting unit, and a green light-emitting unit. Alternatively, as a combination of light-emitting units with high reliability, each of blue, red, and green may be a fluorescent light-emitting unit.

[0415] In addition, in the case of a configuration in which the above-mentioned blue fluorescent light-emitting unit and a blue fluorescent light-emitting unit are combined, it is preferable to use it in combination with a device (e.g., a quantum dot device) that has a function of converting the blue light emitted from the light-emitting unit into another color.

[0416] This embodiment mode can be implemented by appropriately combining at least a part of it with other embodiment modes described in this specification. [Explanation of symbols]

[0417] 100A: display device, 100B: display device, 100C: display device, 100D: display device, 100E: display device, 101: display panel, 101a: area, 101b: area, 101c: area, 102a: housing, 102b: housing, 102c: housing, 103a: hinge, 103b: hinge, 103c: hinge, 104a: curved surface, 104b: curved surface, 105: flat surface, 105a: curved surface, 105b: curved surface, 106: grip portion, 107: receiving coil, 108: receiving circuit, 109: charger, 111: columnar body, 113a: unit, 113b: unit, 114: columnar body, 1 15: columnar body, 116a: gear, 116b: gear, 117: battery, 118: protection circuit, 119: control circuit, 120: sensor, 121: comparator, 122: transistor, 123: capacitor, 125: antenna, 126: antenna, 130: image, 131: keyboard, 132: icon, 135a: input / output unit, 135b: input / output unit, 136a: camera, 136b: camera, 137: sensor, 138: display panel, 139: display panel, 140: solar cell, 141: thin-film solar cell, 145: external interface, 146: transmission / reception unit unit, 147: speaker, 148: camera, 149: microphone, 150: stylus, 200: display device, 210: display device, 300: pixel, 301: pixel, 400: pixel circuit, 400EL: pixel circuit, 400LC: pixel circuit, 401: circuit, 401EL: circuit, 401LC: circuit, 501: pixel circuit, 502: pixel section, 504: drive circuit section, 504a: gate driver, 504b: source driver, 506: protection circuit, 507: terminal section, 550: transistor, 552: transistor, 554: transistor, 560: capacitor, 562: capacitor , 570: liquid crystal device, 572: light emitting device, 600: television device, 601: control unit, 602: memory unit, 603: communication control unit, 604: image processing circuit, 605: decoder circuit, 606: video signal receiving unit, 607: timing controller, 608: source driver, 609: gate driver, 620: display panel, 621: pixel, 630: system bus, 700: display panel, 700A: display panel, 702: pixel unit, 704: source driver circuit unit, 706: gate driver circuit unit, 708: FPC terminal unit, 710: wiring, 716: FPC,717: IC, 730: insulating layer, 732: sealing layer, 736: colored layer, 738: light-shielding layer, 740: support substrate, 741: protective layer, 741a: insulating layer, 741b: insulating layer, 741c: insulating layer, 742: adhesive layer, 743: resin layer, 744: insulating layer, 745: support substrate, 746: insulating layer, 747: adhesive layer, 749: protective layer, 750: transistor, 752: transistor, 760: wiring, 761: conductive layer , 770: insulating layer, 772: conductive layer, 780: anisotropic conductive film, 782: light-emitting device, 786: EL layer, 788: conductive layer, 790: capacitor, 1101: electrode, 1102: electrode, 1103: EL layer, 1109: charge generation layer, 1111: hole injection layer, 1112: hole transport layer, 1113: light-emitting layer, 1114: electron transport layer, 1115: electron injection layer, 1120: light-emitting region, 1123: light-emitting unit,

Claims

1. A display device having a flexible display panel, first to third housings, and a battery, the display panel has first to third regions, At least a portion of the first region is fixed to the first housing; At least a portion of the second region is fixed to the second housing; At least a portion of the third region is fixed to the third housing; When the display panel is laid out flat, the second region is provided between the first region and the third region, the first housing has a first portion having a first thickness, and a second portion having a second thickness greater than the first thickness and housing the battery; When the display panel is folded, a first curved surface having a convex display surface side is formed from the first region to the second region, When the display panel is folded, a second curved surface having a concave surface facing the display surface is formed from the second region to the third region, A display device, wherein when the display panel is laid out flat, the center of gravity of the entire display device is located in the second portion.

2. A display device having a flexible display panel, first to third housings, and a battery, the display panel has first to third regions, At least a portion of the first region is fixed to the first housing; At least a portion of the second region is fixed to the second housing; At least a portion of the third region is fixed to the third housing; When the display panel is laid out flat, the second region is provided between the first region and the third region, the first housing has a first portion having a first thickness, and a second portion having a second thickness greater than the first thickness and housing the battery; When the display panel is folded, a first curved surface having a convex display surface side is formed from the first region to the second region, When the display panel is folded, a second curved surface having a concave surface facing the display surface is formed from the second region to the third region, A display device, wherein when the display panel is folded, the second curved surface has an area facing the second portion.

3. A display device having a flexible display panel, first to third housings, and a battery, the display panel has first to third regions, At least a portion of the first region is fixed to the first housing; At least a portion of the second region is fixed to the second housing; At least a portion of the third region is fixed to the third housing; When the display panel is laid out flat, the second region is provided between the first region and the third region, the first housing has a first portion having a first thickness, and a second portion having a second thickness greater than the first thickness and housing the battery; When the display panel is folded, a first curved surface having a convex display surface side is formed from the first region to the second region, When the display panel is folded, a second curved surface having a concave surface facing the display surface is formed from the second region to the third region, When the display panel is folded, a radius of curvature R1 of the first curved surface is larger than a radius of curvature R2 of the second curved surface; A display device, wherein when the display panel is folded, the second curved surface has an area facing the second portion.

4. In any one of claims 1 to 3, A display device in which an area that cannot be seen because the display panel is folded is not displayed.

5. In any one of claims 1 to 4, A display device that changes the orientation of an image according to the inclination of the display panel when the display panel is laid out flat.

Images