Display device

Abstract

To provide a display device with high numerical aperture.SOLUTION: The display device comprises in a pixel: a layer including a first transistor, a second transistor, a first insulator layer, a second insulator layer, a conductive layer, a pixel electrode and a liquid crystal material; and a common electrode. The first insulator layer is positioned on a channel formation region of the first transistor. The conductive layer is positioned on the first insulator layer. The second insulator layer is positioned on the first transistor, the second transistor, the first insulator layer, and the conductive layer. The pixel electrode is positioned on the second insulator layer, the layer including the liquid crystal material is positioned on the pixel electrode, and the common electrode is positioned on the layer including the liquid crystal material. The common electrode overlaps with the conductive layer via the layer including the liquid crystal material and the pixel electrode. The pixel includes a first connection part where the conductive layer is electrically connected to the first transistor and a second connection part where the pixel electrode is electrically connected to the second transistor. The conductive layer, the pixel electrode and the common electrode respectively include functions of transmitting visible light.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One embodiment of the present invention relates to a display device, a display module, and an electronic device.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. Examples of the technical field of one embodiment of the present invention include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device (e.g., a touch sensor), an input / output device (e.g., a touch panel), a driving method thereof, or a manufacturing method thereof. [Background technology]

[0003] Flat panel displays, such as liquid crystal displays and light-emitting displays, are widely used as display devices. Silicon is mainly used as the semiconductor material for the transistors that make up these display devices, but in recent years, technology has been developed to use transistors that use metal oxides in the pixels of display devices.

[0004] Patent Documents 1 and 2 disclose techniques for using a transistor using a metal oxide as a semiconductor material as a switching element of a pixel of a display device.

[0005] Furthermore, Patent Document 3 discloses a memory device having a structure in which a transistor with extremely low off-state current is used as a memory cell. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-123861 A [Patent Document 2] JP 2007-96055 A [Patent Document 3] JP 2011-119674 A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of one embodiment of the present invention is to provide a display device with high visible light transmittance. Another object of one embodiment of the present invention is to provide a display device with a high aperture ratio. Another object of one embodiment of the present invention is to provide a display device with low power consumption. Another object of one embodiment of the present invention is to provide a highly reliable display device. Another object of one embodiment of the present invention is to provide a display device that can operate stably in a wide temperature range. Another object of one embodiment of the present invention is to provide a highly convenient display device.

[0008] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than these can be extracted from the description of the specification, drawings, and claims. [Means for solving the problem]

[0009] One embodiment of the present invention is a display device including a pixel having a first transistor, a second transistor, a first insulating layer, a second insulating layer, a first conductive layer, a pixel electrode, a layer including a liquid crystal material, and a common electrode. The first insulating layer is located over a channel formation region of the first transistor. The first conductive layer is located over the first insulating layer. The second insulating layer is located over the first transistor, the second transistor, the first insulating layer, and the first conductive layer. The pixel electrode is located over the second insulating layer. The layer including a liquid crystal material is located over the pixel electrode. The common electrode is located over the layer including a liquid crystal material. The common electrode has a region overlapping with the first conductive layer through the layer including a liquid crystal material and the pixel electrode. The pixel further includes a first connection portion and a second connection portion. In the first connection portion, the first conductive layer is electrically connected to the first transistor. In the second connection portion, the pixel electrode is electrically connected to the second transistor. The first conductive layer, the pixel electrode, and the common electrode each have a function of transmitting visible light.

[0010] The pixel preferably further comprises a second conductive layer. The first conductive layer and the second conductive layer are preferably located on the same surface. The first conductive layer and the second conductive layer are preferably electrically insulated from each other. The common electrode preferably has an area overlapping with the second conductive layer via the layer containing a liquid crystal material and the pixel electrode.

[0011] It is preferable that the visible light transmittance in the layer containing the liquid crystal material is higher when no voltage is applied between the pixel electrode and the common electrode than when a voltage is applied between the pixel electrode and the common electrode.

[0012] The layer containing the liquid crystal material preferably has a polymeric material. The polymeric material is preferably a copolymer of a polyfunctional monomer and a monofunctional monomer. The polyfunctional monomer preferably has a phenyl benzoate skeleton. The monofunctional monomer preferably has a cyclohexylbenzene skeleton.

[0013] In the first connection portion, the first transistor preferably has a function of transmitting visible light.

[0014] In the second connection portion, the second transistor preferably has a function of transmitting visible light.

[0015] The pixel preferably further comprises a third conductive layer. The first conductive layer and the third conductive layer are preferably located on the same surface. The first conductive layer and the third conductive layer are preferably electrically insulated from each other. In the second connection, the pixel electrode preferably has a region in contact with the third conductive layer, and the third conductive layer preferably has a region in contact with the source or drain of the second transistor.

[0016] The source or drain of the second transistor preferably has a function of transmitting visible light.

[0017] The first insulating layer is preferably located on the first transistor and preferably has a planarizing function.

[0018] At least one of the gate, source, and drain of the first transistor and the gate, source, and drain of the second transistor preferably includes a first layer and a second layer on the first layer, and the second layer preferably has a smaller resistance than the first layer.

[0019] Alternatively, at least one of the gate, source, and drain of the first transistor and the gate, source, and drain of the second transistor preferably has a first layer, a second layer on the first layer, and a third layer on the second layer. The second layer preferably has a lower resistance than the first layer, and the third layer preferably has a lower visible light reflectance than the second layer. The second layer and the third layer preferably contain at least one of the same metal elements.

[0020] The display device according to one embodiment of the present invention preferably has a function of displaying images by a field sequential driving method.

[0021] One embodiment of the present invention is a display module including a display device having any of the above structures and a light-emitting device having a light-emitting element, the light-emitting device having a function of displaying an image, and light emitted by the light-emitting element is extracted through the display device.

[0022] One aspect of the present invention is a module having a display device of any of the above configurations, and having a connector such as a flexible printed circuit (hereinafter referred to as FPC) or a TCP (Tape Carrier Package) attached, or a module having an integrated circuit (IC) mounted by a COG (Chip On Glass) method or a COF (Chip On Film) method, etc.

[0023] One embodiment of the present invention is an electronic device including any of the above modules and at least one of an antenna, a battery, a housing, a camera, a speaker, a microphone, and an operation button. Effect of the Invention

[0024] According to one embodiment of the present invention, a display device having high transmittance of visible light can be provided. According to one embodiment of the present invention, a display device having a high aperture ratio can be provided. According to one embodiment of the present invention, a display device having low power consumption can be provided. According to one embodiment of the present invention, a display device having high reliability can be provided. According to one embodiment of the present invention, a display device capable of stable operation in a wide temperature range can be provided. According to one embodiment of the present invention, a display device having high convenience can be provided.

[0025] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Effects other than these can be extracted from the description in the specification, drawings, and claims. [Brief description of the drawings]

[0026] [Figure 1] 1A and 1B are cross-sectional views showing an example of a display device. [Diagram 2] FIG. 2 is a circuit diagram showing an example of a pixel. [Diagram 3] 3A and 3B are a top view and a cross-sectional view illustrating an example of a display module. [Figure 4] FIG. 4 is a top view showing an example of a pixel. [Diagram 5] 5A, 5B, 5C, and 5D are cross-sectional views showing examples of a display module. [Figure 6] FIG. 6 is a cross-sectional view showing an example of a display module. [Figure 7] FIG. 7 is a top view showing an example of a pixel. [Figure 8] FIG. 8 is a cross-sectional view showing an example of a display module. [Figure 9] FIG. 9 is a cross-sectional view showing an example of a display module. [Figure 10] FIG. 10 is a cross-sectional view showing an example of a display module. [Figure 11] FIG. 11 is a cross-sectional view showing an example of a display module. [Figure 12] 12A, 12B, 12C, and 12D are diagrams showing examples of electronic devices. [Figure 13] 13A, 13B, 13C, and 13D are diagrams showing examples of electronic devices. [Figure 14] 14A, 14B, and 14C are diagrams showing examples of electronic devices. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that the modes 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 should not be interpreted as being limited to the description of the embodiments shown below.

[0028] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and the repeated explanations are omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be used.

[0029] In addition, for ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings.

[0030] In addition, the words "film" and "layer" can be interchanged depending on the case or situation. For example, the term "conductive layer" can be changed to the term "conductive film". Or, for example, the term "insulating film" can be changed to the term "insulating layer".

[0031] (Embodiment 1) In this embodiment, a display device and a display module according to one embodiment of the present invention will be described with reference to FIGS.

[0032] A display device according to one embodiment of the present invention includes at least a liquid crystal element and two transistors in one pixel. The display device according to one embodiment of the present invention has a function of adding a correction signal to an image signal. The correction signal is added to the image signal by capacitive coupling and supplied to the liquid crystal element. Therefore, the liquid crystal element can display a corrected image.

[0033] By adding a correction signal to an image signal, it is possible to apply a higher voltage to drive the liquid crystal element compared to when only an image signal is used, which makes it easier to drive liquid crystal elements that require a relatively high drive voltage.

[0034] Furthermore, this correction allows, for example, the liquid crystal element to express more gray levels than can be expressed using only image signals.

[0035] Moreover, this correction allows the liquid crystal element to be driven with a voltage higher than the output voltage of the source driver. Since the voltage supplied to the liquid crystal element can be changed to a desired value within the pixel, an existing source driver can be reused, and the cost of designing a new source driver can be reduced. In addition, the output voltage of the source driver can be prevented from becoming too high, and the power consumption of the source driver can be reduced.

[0036] By applying a high voltage to drive the liquid crystal element, the display device can be used in a wide temperature range and can perform display with high reliability in both low-temperature and high-temperature environments. For example, the display device of one embodiment of the present invention can be used as a display device for vehicles or cameras.

[0037] In addition, because the liquid crystal element can be driven by applying a high voltage, the response speed of the liquid crystal can also be improved by overdriving, which temporarily increases the voltage applied to the liquid crystal element to quickly change the orientation of the liquid crystal.

[0038] The correction signal is generated, for example, by an external device and written to each pixel. The correction signal may be generated in real time using the external device, or the correction signal may be read out from a recording medium and synchronized with the image signal.

[0039] In the display device of one embodiment of the present invention, a new image signal can be generated by a pixel to which a correction signal is supplied without changing the image signal to be supplied. Compared to the case where a new image signal itself is generated by using an external device, the load on the external device can be reduced. In addition, an operation for generating a new image signal by a pixel can be performed in a small number of steps, and the display device can be used even in a display device with a large number of pixels and a short horizontal period.

[0040] In addition, in the display device of one embodiment of the present invention, the liquid crystal element has a pair of electrodes and a layer containing a liquid crystal material. The display device of one embodiment of the present invention typically uses a mode (also called a reverse mode) in which the layer containing the liquid crystal material transmits visible light when no voltage is applied between the pair of electrodes (off state) and the layer containing the liquid crystal material scatters visible light when a voltage is applied between the pair of electrodes (on state). This can increase the transmittance of visible light of the display device when the display device is not displaying an image. Therefore, the display device of one embodiment of the present invention can be used as, for example, a transparent display (also called a see-through display).

[0041] When the reverse mode is applied, the layer containing the liquid crystal material preferably contains a liquid crystal material and a polymer material. Specifically, the layer containing the liquid crystal material may be made of polymer liquid crystal, polymer dispersed liquid crystal (PDLC), polymer network liquid crystal (PNLC), polymer stabilized liquid crystal, or the like.

[0042] When the reverse mode is applied, the driving voltage of the liquid crystal element tends to be relatively high. As described above, the display device of one embodiment of the present invention has a suitable structure when the reverse mode is applied because the liquid crystal element can be driven by applying a high voltage.

[0043] In addition, in the display device according to one embodiment of the present invention, each pixel preferably includes at least two capacitors. Both of the capacitors are formed using a material that transmits visible light. This allows the pixel to have both a high aperture ratio and a large storage capacitance.

[0044] By increasing the aperture ratio of the display device (also called the aperture ratio of the pixel), the transmittance of visible light in the display device can be increased, making it suitable for use as a see-through display. In addition, by increasing the aperture ratio, the light extraction efficiency (or pixel transmittance) can be increased. This allows the power consumption of the display device to be reduced.

[0045] By increasing the retention capacitance of the pixel, a stable display can be achieved even if the leakage current of the liquid crystal element is large. In addition, it is possible to drive a liquid crystal material with a large capacity. Therefore, the range of liquid crystal materials to be selected can be expanded.

[0046] By increasing the pixel storage capacitance, the pixel gradation can be maintained for a long period of time. Specifically, by increasing the pixel storage capacitance, the image signal written in the previous period can be maintained without rewriting the image signal every frame period, and the pixel gradation can be maintained for a period of several frames or several tens of frames, for example.

[0047] In addition, a connection portion between an electrode of a transistor and an electrode of a capacitor or a liquid crystal element preferably has a function of transmitting visible light, which can increase the aperture ratio of a pixel.

[0048] Furthermore, the display device of one embodiment of the present invention does not need to include a polarizing plate, which can increase the transmittance of visible light in the display device.

[0049] Furthermore, the display device of one embodiment of the present invention does not need to have a light-blocking layer such as a black matrix, which can improve the transmittance of a pixel.

[0050] <Example of cross-sectional configuration of a display device> 1A shows a cross-sectional view of a display device 10. The display device 10 shown in FIG. 1A includes a substrate 131, a transistor SW11, a transistor SW12, an insulating layer 215, a conductive layer 115a, a conductive layer 115b, an insulating layer 121, a pixel electrode 111a, a layer 112 containing a liquid crystal material, a common electrode 113, and a substrate 132.

[0051] The display device 10 includes, in each pixel, a liquid crystal element 110, two transistors (a transistor SW11 and a transistor SW12), and two capacitance elements (a capacitance element Cw and a capacitance element Cs).

[0052] The transistor SW11 and the transistor SW12 are each located on a substrate 131. An insulating layer 215 is located on the transistor SW11 and the transistor SW12. The conductive layer 115a and the conductive layer 115b are each located on the insulating layer 215. An insulating layer 121 is located on the transistor SW11, the transistor SW12, the insulating layer 215, the conductive layer 115a, and the conductive layer 115b. The pixel electrode 111a is located on the insulating layer 121. The layer 112 containing a liquid crystal material is located on the pixel electrode 111a. The common electrode 113 is located on the layer 112 containing a liquid crystal material. The substrate 132 is located on the common electrode 113.

[0053] The common electrode 113 has a region overlapping with the conductive layer 115a with the layer 112 containing a liquid crystal material and the pixel electrode 111a interposed therebetween. The conductive layer 115a is electrically connected to the source or drain of the transistor SW11. The pixel electrode 111a is electrically connected to the source or drain of the transistor SW12. The conductive layer 115a, the conductive layer 115b, the pixel electrode 111a, and the common electrode 113 each have a function of transmitting visible light.

[0054] The pixel electrode 111a, the layer 112 containing a liquid crystal material, and the common electrode 113 can function as a liquid crystal element 110. The pixel electrode 111a and the common electrode 113 are stacked with the layer 112 containing a liquid crystal material interposed therebetween.

[0055] The conductive layer 115a, the insulating layer 121, and the pixel electrode 111a can function as one capacitance element Cw, and the conductive layer 115b, the insulating layer 121, and the pixel electrode 111a can function as one capacitance element Cs.

[0056] The capacitance of the capacitive element Cw is preferably larger than the capacitance of the capacitive element Cs. For example, the area of ​​the region where the pixel electrode 111a and the conductive layer 115a overlap is preferably larger than the area of ​​the region where the pixel electrode 111a and the conductive layer 115b overlap.

[0057] The configuration of the display device 10 can also be applied to a touch panel. The touch panel 11 shown in Fig. 1B is an example in which a touch sensor TC is mounted on the display device 10 shown in Fig. 1A. By providing the touch sensor TC in a position close to the display surface of the display device 10, the sensitivity of the touch sensor TC can be increased.

[0058] There is no limitation on a sensing element (also referred to as a sensor element) included in a touch panel of one embodiment of the present invention. Various sensors capable of detecting the proximity or contact of a sensing object such as a finger or a stylus can be used as the sensing element.

[0059] As the sensor type, various types can be used, such as a capacitance type, a resistive film type, a surface acoustic wave type, an infrared type, an optical type, and a pressure sensitive type.

[0060] The capacitance type includes a surface capacitance type, a projected capacitance type, etc. The projected capacitance type includes a self-capacitance type, a mutual capacitance type, etc. The mutual capacitance type is preferable because it enables simultaneous multi-point detection.

[0061] The touch panel of one embodiment of the present invention can have various configurations, such as a configuration in which a display device and a detector element that are separately manufactured are bonded to each other, or a configuration in which electrodes that constitute a detector element are provided on one or both of a substrate supporting a display element and an opposing substrate.

[0062] <Pixel circuit configuration example> The display device 10 has a plurality of pixels 15 arranged in a matrix of m rows and n columns (m and n are each an integer greater than or equal to 1). Fig. 2 shows a circuit diagram of a pixel 15(i,j) (i is an integer greater than or equal to 1 and less than or equal to m, and j is an integer greater than or equal to 1 and less than or equal to n).

[0063] A pixel 15(i,j) includes a transistor SW11, a transistor SW12, a capacitance element Cw, a capacitance element Cs, and a liquid crystal element 110(i,j). Note that in this specification, the transistor SW11, the transistor SW12, the capacitance element Cw, and the capacitance element Cs are collectively referred to as a pixel circuit 120(i,j).

[0064] One of the source and drain of the transistor SW11 is electrically connected to one electrode of the capacitance element Cw. The other electrode of the capacitance element Cw is electrically connected to one of the source and drain of the transistor SW12, one electrode of the capacitance element Cs, and one electrode of the liquid crystal element 110.

[0065] Here, a node to which one of the source or drain of the transistor SW11 and one electrode of the capacitance element Cw are connected is referred to as a node NS, and a node to which the other electrode of the capacitance element Cw, one of the source or drain of the transistor SW12, one electrode of the capacitance element Cs, and one electrode of the liquid crystal element 110 are connected is referred to as a node NA.

[0066] The gate of the transistor SW11 is electrically connected to the wiring GL1(i). The gate of the transistor SW12 is electrically connected to the wiring GL2(i). The other of the source and the drain of the transistor SW11 is electrically connected to the wiring SL1(j). The other of the source and the drain of the transistor SW12 is electrically connected to the wiring SL2(j).

[0067] The other electrode of the capacitor Cs is electrically connected to the wiring CSCOM. The other electrode of the liquid crystal element 110 is electrically connected to the wiring VCOM. Any potential can be supplied to each of the wiring CSCOM and the wiring VCOM.

[0068] The wirings GL1(i) and GL2(i) can be called scan lines and have a function of controlling the operation of transistors. The wiring SL1(j) has a function as a signal line for supplying an image signal. The wiring SL2(j) has a function as a signal line for writing data to the node NA.

[0069] 2 has a backgate electrically connected to the gate, the connection of the backgate is not limited to this, and the transistor does not necessarily have to have a backgate.

[0070] By making the transistor SW11 non-conductive, the potential of the node NS can be maintained. Also, by making the transistor SW12 non-conductive, the potential of the node NA can be maintained. Also, by supplying a predetermined potential to the node NS via the transistor SW11 while the transistor SW12 is in a non-conductive state, the potential of the node NA can be changed in response to a change in the potential of the node NS due to capacitive coupling via the capacitance element Cw.

[0071] In pixel 15(i,j), the correction signal written to node NA from line SL2(j) is capacitively coupled with the image signal supplied from line SL1(j) and supplied to liquid crystal element 110. Therefore, the liquid crystal element 110 can display a corrected image.

[0072] By using a transistor with extremely low off-state current as the transistor SW11, the potential of the node NS can be held for a long time. Similarly, by using a transistor with extremely low off-state current as the transistor SW12, the potential of the node NA can be held for a long time. An example of a transistor with extremely low off-state current is a transistor using metal oxide in a channel formation region (hereinafter, OS transistor). A transistor having silicon in a channel formation region (hereinafter, Si transistor) may be used as the transistor included in the pixel. Examples of Si transistors include a transistor having amorphous silicon and a transistor having crystalline silicon (typically, low-temperature polysilicon or single crystal silicon). Alternatively, both an OS transistor and a Si transistor may be used.

[0073] For example, when the correction signal and the image signal are rewritten every frame period, the transistors SW11 and SW12 may be OS transistors or Si transistors. When the potential of the node NS or the node NA needs to be held for a long time, it is preferable to use OS transistors rather than Si transistors for the transistors SW11 and SW12.

[0074] <Display module configuration example 1> FIG. 3A shows a top view of the display module 50, and FIG. 3B shows a cross-sectional view of the display module 50. As shown in FIG.

[0075] A display module 50 shown in FIGS. 3A and 3B includes a display device, a flexible printed circuit board (FPC) connected to the display device, and a light unit 30 (omitted in FIG. 3A).

[0076] The display device includes a display area 100, a gate driver GD_L, and a gate driver GD_R.

[0077] The display area 100 has a plurality of pixels 15 and has the function of displaying an image.

[0078] As shown in FIG. 3A, a pixel 15(i,j) is electrically connected to a wiring GL1(i), a wiring GL2(i), a wiring SL1(j), and a wiring SL2(j).

[0079] As shown in Fig. 3B, pixel 15(i,j) has a configuration in which pixel circuit 120(i,j) and liquid crystal element 110(i,j) shown in Fig. 2 are stacked. The pixel circuit 120(i,j) is electrically connected to a gate driver GD (corresponding to gate driver GD_L and gate driver GD_R shown in Fig. 3A).

[0080] By controlling the scattering or transmission of light in liquid crystal element 110(i,j), display module 50 can display an image. Specifically, liquid crystal element 110(i,j) scatters light 32 emitted from light unit 30 and emits scattered light 34 to the outside, thereby allowing display module 50 to display an image.

[0081] The light unit 30 has at least a light source. As the light source, an LED (Light Emitting Diode), an organic EL (Electroluminescence) element, etc. As the light source, for example, LEDs of three colors, red, green, and blue, can be used.

[0082] The light unit 30 may have one or both of a structure having a light guide function and a structure having a light diffusion function. For example, the light unit 30 may have at least one of a light guide plate (also called a light guide), a brightness enhancing film, a light diffusion film, and a light diffusion plate. For example, it is preferable that the light emitted by the light source enters the display device via the light guide plate and the light diffusion film.

[0083] Since the display module 50 uses an edge-lit light as a light source, the area through which visible light passes in the display device can be made wider and the transmittance of visible light in the display device can be made higher than when a direct-light type backlight is used. This allows the view behind the display module 50 to be seen through the display module 50. For example, as shown in FIG. 3B, at least a part of the external light 35 incident on the pixel 15(i,j) passes through the display module 50 and is emitted to the outside of the display module 50.

[0084] In addition, the display device of one embodiment of the present invention preferably has a function of displaying images by a field sequential driving method. The field sequential driving method is a driving method for performing color display by time division. Specifically, light-emitting elements of each color, such as red, green, and blue, are sequentially turned on with a time lag, and pixels are driven in synchronization with the light-emitting elements to perform color display based on a time-sequential additive color mixing method.

[0085] When the field sequential driving method is applied, since it is not necessary to configure one pixel with multiple sub-pixels of different colors, the aperture ratio of the pixel can be increased. In addition, it is possible to achieve high resolution display devices. In addition, since it is not necessary to provide a colored layer such as a color filter, there is no light absorption by the colored layer, and the transmittance of the pixel can be improved. As a result, the required brightness can be obtained with less power, and low power consumption can be achieved. In addition, the manufacturing process of the display device can be simplified, reducing manufacturing costs.

[0086] When a field sequential driving method is applied, a high frame frequency is required. Since the display device of one embodiment of the present invention has two capacitors in one pixel, the storage capacitance of the pixel is large and a high voltage can be supplied to the liquid crystal element, thereby improving the response speed of the liquid crystal element. For example, the response speed of the liquid crystal element can be improved by overdrive driving, in which the voltage applied to the liquid crystal element is temporarily increased to quickly change the alignment of the liquid crystal. Therefore, it can be said that the display device of one embodiment of the present invention has a suitable configuration when a field sequential driving method, which requires a high frame frequency, is applied.

[0087] The display device according to one embodiment of the present invention may display in a single color. Since it is not necessary to configure one pixel with a plurality of subpixels of different colors even in a display device that displays in a single color, the aperture ratio of the pixel can be increased. Furthermore, the display device can have a high resolution. Furthermore, since it is not necessary to provide a colored layer such as a color filter, light is not absorbed by the colored layer, and the transmittance of the pixel can be improved. As a result, the required luminance can be obtained with less power, and thus low power consumption can be achieved. Furthermore, the manufacturing process of the display device can be simplified, and the manufacturing cost can be reduced.

[0088] In addition, in the display device of one embodiment of the present invention, one pixel may be composed of a plurality of subpixels of different colors. For example, a pixel unit may be composed of a subpixel that exhibits red, a subpixel that exhibits green, and a subpixel that exhibits blue, thereby enabling full-color display in the display region 100. Note that the colors of the subpixels are not limited to red, green, and blue. For example, subpixels that exhibit white, yellow, magenta, cyan, or the like may be used in the pixel unit.

[0089] The display device may include one or more of a scanning line driving circuit (gate driver), a signal line driving circuit (source driver), and a driving circuit for a touch sensor. Alternatively, one or more of these may be externally attached. The display module 50 shown in Figures 3A and 3B includes a gate driver and an integrated circuit (IC) having a source driver is externally attached.

[0090] The gate driver GD_L and the gate driver GD_R are disposed opposite each other across the display region 100. Selection signals are simultaneously supplied to the wiring GL1(i) from both the gate driver GD_L and the gate driver GD_R. Similarly, selection signals are simultaneously supplied to the wiring GL2(i) from both the gate driver GD_L and the gate driver GD_R. By simultaneously supplying selection signals to one wiring from both the gate driver GD_L and the gate driver GD_R, the supply capability of the selection signal to the wiring can be improved. Depending on the purpose, one of the gate driver GD_L and the gate driver GD_R may be omitted.

[0091] Signals and power are supplied to the gate driver GD_L and the gate driver GD_R from the outside via the FPC.

[0092] The source driver SD is electrically connected to a terminal of the display device by using a chip on glass (COG) method or a chip on film (COF) method, etc. Signals such as image signals or correction signals are supplied from the source driver SD to the wiring SL1(j) and the wiring SL2(j).

[0093] <Pixel top layout example 1> A top view of the pixel 15(i,j) is shown in Fig. 4. Fig. 4 is a top view of the laminated structure from the wiring GL1(i) to the pixel electrode 111a, as viewed from the pixel electrode 111a side.

[0094] The pixel has a connection portion 71 and a connection portion 72. In the connection portion 71, the conductive layer 115a is electrically connected to the transistor SW11. Specifically, the conductive layer 115a and the conductive layer 222p are electrically connected. In the connection portion 72, the pixel electrode 111a is electrically connected to the transistor SW12. Specifically, the pixel electrode 111a and the conductive layer 222f are electrically connected.

[0095] It is preferable that each of the connection portion 71 and the connection portion 72 has a region that transmits visible light. For example, by using a conductive material that transmits visible light for the conductive layers (conductive layers 222p and 222f in FIG. 4) that function as the source or drain in the transistor SW11 and the transistor SW12, the connection portion 71 and the connection portion 72 can be provided with a region that transmits visible light, and the aperture ratio of the pixel 15(i,j) can be increased. This can increase the transmittance of visible light in the display device 10. In addition, the region that transmits visible light in the pixel 15(i,j) can be widened.

[0096] 4, the wiring SL1(j) functioning as a signal line is electrically connected to the semiconductor layer 231b through the conductive layer 222q. Note that the conductive layer 222q may not be provided and the wiring SL1(j) and the semiconductor layer 231b may be in contact with each other.

[0097] Similarly, the wiring SL2(j) functioning as a signal line is electrically connected to the semiconductor layer 231a through the conductive layer 222g. Alternatively, the conductive layer 222g may not be provided and the wiring SL2(j) and the semiconductor layer 231a may be in contact with each other.

[0098] Conductive materials that transmit visible light may have a higher resistivity than conductive materials that block visible light, such as copper and aluminum. To prevent signal delay, bus lines such as scanning lines and signal lines are preferably formed using a conductive material (metal material) with low resistivity, such as copper or aluminum. This makes it possible to reduce the width of the bus lines or to make the bus lines thinner. However, depending on the size of the pixel, the width of the bus lines, the thickness of the bus lines, etc., a conductive material that transmits visible light may be used for the bus lines.

[0099] Specifically, the wiring SL1(j) and wiring SL2(j) functioning as signal lines are preferably formed using a conductive material with low resistivity. The wiring GL1(i) and wiring GL2(i) functioning as gates and scanning lines are preferably formed using a conductive material with low resistivity. Examples of conductive materials with low resistivity include metals and alloys. The gates 223a and 223b functioning as back gates may be formed using a conductive material that blocks visible light.

[0100] By using a conductive layer that blocks visible light for the gates 223a and 223b, it is possible to prevent light from a light source and external light from being irradiated onto the channel formation regions of the semiconductor layers 231a and 231b. In this way, by overlapping the channel formation regions of the semiconductor layers with a conductive layer that blocks visible light, it is possible to suppress the characteristic fluctuation of the transistor caused by light. This can improve the reliability of the transistor.

[0101] Furthermore, the gate 223a and the gate 223b may be formed using a metal oxide. By using a metal oxide for the gate 223a and the gate 223b, oxygen can be prevented from being extracted from the channel formation regions of the semiconductor layers 231a and 231b. This can improve the reliability of the transistor.

[0102] <Display module cross-sectional configuration example 1> 5A shows a cross-sectional view of the display module 50. Note that the pixel portion corresponds to the cross-sectional view between dashed dotted lines G1-G2 and G3-G4 shown in FIG.

[0103] A display module 50 shown in FIG. 5A has a configuration in which an FPC is connected to a display device.

[0104] The display module of one embodiment of the present invention has high transmittance of visible light because it does not have a polarizing plate. Although the light source is not illustrated in the cross-sectional views shown in FIG. 5A and subsequent figures, the display module of one embodiment of the present invention uses an edge-lit light, and therefore the region through which visible light passes in the display module can be made larger than that in the case of using a direct-type backlight. Therefore, the display module of one embodiment of the present invention has high transmittance of visible light, and the scenery behind the display module can be seen through the display module.

[0105] The display module 50 shown in Figure 5A has a substrate 131, a substrate 132, a transistor SW11, a transistor SW12, an insulating layer 215, a conductive layer 115a, a conductive layer 115b, a conductive layer 115c, an insulating layer 121, a pixel electrode 111a, a layer 112 containing a liquid crystal material, a common electrode 113, an alignment film 114a, an alignment film 114b, an adhesive layer 141, a spacer KB, etc.

[0106] The display module 50 can display a color image using a field sequential driving method. Therefore, the display module 50 shown in FIG. 5A does not have a colored layer such as a color filter. Furthermore, the display module 50 does not have a light-shielding layer such as a black matrix. Therefore, the transmittance of the pixel can be improved.

[0107] The transistors SW11 and SW12 are located on the substrate 131.

[0108] The transistor SW11 has a gate 221b, a gate insulating layer 211, a semiconductor layer 231b, a conductive layer 222p, a conductive layer 222q, an insulating layer 213, an insulating layer 214, and a gate 223b. One of the conductive layer 222p and the conductive layer 222q functions as a source, and the other functions as a drain. The insulating layer 213 and the insulating layer 214 function as gate insulating layers. Furthermore, the conductive layer 222b may be a component of the transistor SW11. The conductive layer 222b is connected to the conductive layer 222q.

[0109] Here, the gate 221b and the wiring GL1(i) are composed of the same conductive layer. It can be said that one conductive layer has a portion that functions as the gate 221b and a portion that functions as the wiring GL1(i). The conductive layer 222b corresponds to a part of the wiring SL1(j).

[0110] The transistor SW12 includes a gate 221a, a gate insulating layer 211, a semiconductor layer 231a, a conductive layer 222f, a conductive layer 222g, an insulating layer 213, an insulating layer 214, and a gate 223a. One of the conductive layer 222f and the conductive layer 222g functions as a source, and the other functions as a drain. The insulating layer 213 and the insulating layer 214 function as gate insulating layers. Furthermore, the conductive layer 222a may be a component of the transistor SW12. The conductive layer 222a is connected to the conductive layer 222g.

[0111] Here, the gate 221a and the wiring GL2(i) are composed of the same conductive layer. It can be said that one conductive layer has a portion that functions as the gate 221a and a portion that functions as the wiring GL2(i). The conductive layer 222a corresponds to a part of the wiring SL2(j).

[0112] The conductive layers 222f, 222g, 222p, and 222q are formed of a material that transmits visible light. Therefore, at least a part of the external light 35 shown in FIG. 5A is transmitted through the connection portion (corresponding to the connection portion 72 in FIG. 4) between the conductive layer 222f and the conductive layer 115c, and is emitted to the outside of the display module. Similarly, the connection portion (corresponding to the connection portion 71 in FIG. 4) between the conductive layer 222p and the conductive layer 115a can also transmit visible light. This can increase the aperture ratio of the pixel, and can increase the transmittance of visible light in the display module.

[0113] 5B, the source and drain of the transistor may be formed of a material that blocks visible light. The conductive layer 222e can be formed of the same material and in the same process as the conductive layer 222a.

[0114] As shown in FIG. 5B, the pixel electrode 111a may be directly connected to the source or drain of the transistor (conductive layer 222e in this case) without the conductive layer 115c therebetween.

[0115] As shown in Figures 5C and 5D, the gate of the transistor may have a laminated structure. The source and drain of the transistor, as well as wiring such as a scanning line and a signal line, may also have a laminated structure. The electrodes of the transistor and the wiring electrically connected to the transistor preferably have low resistance. For example, the electrodes and wiring are preferably made of a metal material with low resistivity, such as copper or aluminum.

[0116] Here, when copper is used, the adhesion may be low depending on the material of the underlayer (substrate, insulating layer, etc.), so it is preferable to laminate the copper film on a film that has high adhesion to the underlayer. Also, in order to prevent copper from diffusing into other layers, it is preferable to laminate the copper film on a film with high barrier properties.

[0117] 5C, the gate 221m, the conductive layer 222m, and the gate 223m each preferably include at least one of titanium, molybdenum, manganese, and aluminum, and the gate 221n, the conductive layer 222n, and the gate 223n each preferably include one or both of copper and aluminum.

[0118] Note that the materials of the gates 221m, 221n, the conductive layers 222m, 222n, and the gates 223m, 223n are not limited to those mentioned above. For example, it is preferable that the gate 221n has a smaller resistance value than the gate 221m. For example, it is preferable that the conductive layer 222n has a smaller resistance value than the conductive layer 222m. For example, it is preferable that the gate 223n has a smaller resistance value than the gate 223m.

[0119] In addition, metal materials may have high reflectance. Therefore, it is preferable to suppress the reflectance by performing an oxidation treatment on the surface of the metal film. This makes it possible to suppress the decrease in visibility due to the reflection of external light when viewed from the display surface side.

[0120] 5D, the gate 221s, the conductive layer 222s, and the gate 223s each preferably contain at least one of titanium, molybdenum, manganese, and aluminum. The gate 221t, the conductive layer 222t, and the gate 223t each preferably contain copper. The gate 221u, the conductive layer 222u, and the gate 223u each preferably contain copper oxide.

[0121] The materials of the gates 221s, 221t, and 221u, the conductive layers 222s, 222t, and 222u, and the gates 223s, 223t, and 223u are not limited to those mentioned above. For example, the gate 221t preferably has a smaller resistance value than the gate 221s. The conductive layer 222t preferably has a smaller resistance value than the conductive layer 222s. The gate 223t preferably has a smaller resistance value than the gate 223s. The gate 221u preferably has a lower visible light reflectance than the gate 221t. The conductive layer 222u preferably has a lower visible light reflectance than the conductive layer 222t. The gate 223u preferably has a lower visible light reflectance than the gate 223t. The gates 221t and 221u preferably contain at least one of the same metal elements. The conductive layers 222t and 222u preferably contain at least one of the same metal elements. It is preferable that gate 223t and gate 223u contain at least one of the same metal elements.

[0122] FIG. 5A shows an example in which the transistors SW11 and SW12 have back gates (gates 223a and 223b in FIG. 5A), but they do not necessarily have to have back gates.

[0123] As shown in FIG. 4, it is preferable that two gates of a transistor are electrically connected. A transistor having two gates electrically connected can have a higher field effect mobility and an increased on-state current than other transistors. As a result, a circuit capable of high-speed operation can be manufactured. Furthermore, the area occupied by the circuit portion can be reduced. By using a transistor having a large on-state current, even if the display device is enlarged or highly refined and the number of wirings is increased, the signal delay in each wiring can be reduced and display unevenness can be suppressed. In addition, since the area occupied by the circuit portion can be reduced, the frame of the display device can be narrowed. In addition, by applying such a configuration, a highly reliable transistor can be realized.

[0124] In this embodiment, a case where a metal oxide is used for the semiconductor layers 231a and 231b will be described as an example.

[0125] The gate insulating layer 211 and the insulating layer 213 in contact with the semiconductor layers 231a and 231b are preferably oxide insulating layers. When the gate insulating layer 211 or the insulating layer 213 has a stacked structure, at least the layer in contact with the semiconductor layers 231a and 231b is preferably an oxide insulating layer. This can suppress oxygen vacancies in the semiconductor layers 231a and 231b, thereby improving the reliability of the transistor.

[0126] The insulating layer 214 is preferably a nitride insulating layer, which can prevent impurities from entering the semiconductor layers 231a and 231b and improve the reliability of the transistor.

[0127] The insulating layer 215 preferably has a planarizing function, and is preferably, for example, an organic insulating layer. Note that the insulating layer 215 is not necessarily formed, and the conductive layer 115a and the like may be formed on and in contact with the insulating layer 214.

[0128] The conductive layer 115c is located on the insulating layer 215, the insulating layer 121 is located on the conductive layer 115c, and the pixel electrode 111a is located on the insulating layer 121. The pixel electrode 111a is electrically connected to the conductive layer 222f. Specifically, the conductive layer 222f contacts the conductive layer 115c, and the conductive layer 115c contacts the pixel electrode 111a.

[0129] The conductive layer 115a is located on the insulating layer 215. The conductive layer 115a is in contact with and electrically connected to the conductive layer 222p.

[0130] The conductive layer 115a and the pixel electrode 111a have a portion that overlaps with each other via the insulating layer 121. The conductive layer 115a, the insulating layer 121, and the pixel electrode 111a can function as one capacitance element Cw.

[0131] The conductive layer 115b is located over the insulating layer 215. The conductive layer 115b and the pixel electrode 111a overlap with each other via the insulating layer 121. The conductive layer 115b, the insulating layer 121, and the pixel electrode 111a can function as one capacitor element Cs.

[0132] In this way, the display module 50 has two capacitance elements in one pixel, which makes it possible to increase the storage capacitance of the pixel.

[0133] In addition, the two capacitive elements are both made of a material that transmits visible light and have an overlapping area, which allows the pixel to achieve both a high aperture ratio and a large storage capacitance.

[0134] The capacitance of the capacitive element Cw is preferably larger than the capacitance of the capacitive element Cs. Therefore, the area of ​​the region where the pixel electrode 111a and the conductive layer 115a overlap is preferably larger than the area of ​​the region where the pixel electrode 111a and the conductive layer 115b overlap.

[0135] A pixel electrode 111a is provided on the insulating layer 121. An alignment film 114a is provided on the pixel electrode 111a. A common electrode 113 is provided on the substrate 132, and a spacer KB is provided in contact with the common electrode 113. An alignment film 114b is provided so as to cover the spacer KB and the common electrode 113. A layer 112 containing a liquid crystal material is provided between the alignment films 114a and 114b.

[0136] There are positive-type liquid crystal materials in which the anisotropy (Δε) of the dielectric constant is positive, and negative-type liquid crystal materials in which the anisotropy is negative. In one embodiment of the present invention, either type of material can be used, and an optimal liquid crystal material can be used depending on the mode and design to be applied.

[0137] It is preferable that the absolute value of the dielectric constant anisotropy (Δε) of the liquid crystal material is large in order to reduce the drive voltage of the liquid crystal element 110. Since it is easier to increase the absolute value of the dielectric constant anisotropy (Δε) of a positive type liquid crystal material than of a negative type, the use of a positive type liquid crystal material is preferable because it widens the range of liquid crystal material options.

[0138] If the refractive index anisotropy of the liquid crystal material is large, the light scattering effect is enhanced, and the layer 112 containing the liquid crystal material can be made thinner, thereby reducing the driving voltage.

[0139] In the display device of one embodiment of the present invention, it is preferable to apply a mode (reverse mode) in which the layer 112 containing a liquid crystal material transmits visible light when no voltage is applied between the pair of electrodes (the pixel electrode 111a and the common electrode 113) (off state) and the layer 112 containing a liquid crystal material scatters visible light when a voltage is applied between the pair of electrodes (on state). This can increase the visible light transmittance of the display module 50 when the display module 50 is not displaying an image. Therefore, the display module 50 can be used as a see-through display.

[0140] When such a mode is applied, the layer 112 containing a liquid crystal material preferably comprises a liquid crystal material and a polymer material.

[0141] As the liquid crystal material, it is preferable to use a nematic liquid crystal.

[0142] The polymeric material is preferably a copolymer of a polyfunctional monomer and a monofunctional monomer.

[0143] Examples of the monofunctional monomer include acrylate, methacrylate, etc. Examples of the polyfunctional monomer include diacrylate, triacrylate, dimethacrylate, trimethacrylate, etc.

[0144] The polyfunctional monomer preferably has a phenyl benzoate skeleton. Examples of the polyfunctional monomer include diacrylates having a phenyl benzoate skeleton.

[0145] Examples of materials that can be used as polyfunctional monomers include materials represented by structural formulas (1) to (3).

[0146] [ka]

[0147] The monofunctional monomer preferably has a cyclohexylbenzene skeleton. Examples of the monofunctional monomer include acrylates having a cyclohexylbenzene skeleton.

[0148] Examples of materials that can be used as monofunctional monomers include materials represented by structural formulas (4) to (6).

[0149] [ka]

[0150] For example, the layer 112 containing a liquid crystal material can be formed by irradiating a material layer containing a liquid crystal material, a monomer, and a photopolymerization initiator with light to cure the material layer.

[0151] Note that the liquid crystal element used in the display device of one embodiment of the present invention is not limited to a reverse mode, and various modes can be applied.

[0152] Since the display device of this embodiment is a transmissive liquid crystal display device, a conductive material that transmits visible light is used for both of the pair of electrodes (the pixel electrode 111a and the common electrode 113). In addition, by forming the conductive layers 115a, 115b, and 115c using a conductive material that transmits visible light, it is possible to suppress a decrease in the aperture ratio of the pixel even when the capacitor element Cw and the capacitor element Cs are provided. Note that a silicon nitride film is suitable for the insulating layer 121 that functions as a dielectric of the capacitor element.

[0153] As the conductive material that transmits visible light, for example, a material containing one or more selected from indium (In), zinc (Zn), and tin (Sn) may be used. Specific examples include indium oxide, indium tin oxide (ITO), indium zinc oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium tin oxide containing silicon oxide (ITSO), zinc oxide, and zinc oxide containing gallium. Note that a film containing graphene may also be used. A film containing graphene may be formed by reducing a film containing graphene oxide, for example.

[0154] A conductive film that transmits visible light can be formed using an oxide semiconductor (hereinafter, also referred to as an oxide conductive layer). The oxide conductive layer preferably contains indium, for example, and more preferably contains In-M-Zn oxide (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn, or Hf).

[0155] An oxide semiconductor is a semiconductor material whose resistance can be controlled by at least one of oxygen vacancies and the concentration of impurities such as hydrogen, water, etc. in the film. Therefore, the resistivity of the oxide conductive layer can be controlled by selecting a treatment for increasing at least one of oxygen vacancies and the concentration of impurities in the oxide semiconductor layer or a treatment for decreasing at least one of oxygen vacancies and the concentration of impurities in the oxide semiconductor layer.

[0156] Note that an oxide conductive layer formed using an oxide semiconductor in this manner can also be referred to as an oxide semiconductor layer with high carrier density and low resistance, an oxide semiconductor layer having conductivity, or an oxide semiconductor layer with high conductivity.

[0157] The substrate 131 and the substrate 132 are bonded together by an adhesive layer 141 .

[0158] The FPC is electrically connected to the conductive layer 221c. Specifically, the FPC is in contact with the connector 139, the connector 139 is in contact with the conductive layer 222c, and the conductive layer 222c is in contact with the conductive layer 221c. The conductive layer 221c is formed on the substrate 131, and the conductive layer 222c is formed on the gate insulating layer 211. The conductive layer 221c can be formed in the same process and from the same material as the gates 221a and 221b. The conductive layer 222c can be formed in the same process and from the same material as the conductive layers 222a and 222b.

[0159] <Touch panel> According to one embodiment of the present invention, a display device or a display module equipped with a touch sensor (hereinafter also referred to as a touch panel) can be manufactured.

[0160] 6 shows a cross-sectional view of the display module 51. The display module 51 has a configuration in which a touch sensor is added to the configuration of the display module 50.

[0161] Substrate 180 and substrate 132 are bonded together by adhesive layer 186. Electrodes 181 and 182 are provided on the substrate 132 side of substrate 180. Electrodes 181 and 182 are electrically insulated from each other by insulating layer 185. A connection portion is provided in an area close to the end of substrate 180. At the connection portion, wiring 187 is electrically connected to FPC 2 via conductive layer 188 and connector 189.

[0162] When the electrodes and wiring of the touch sensor are provided at a position overlapping with the opening of the pixel (a portion used for display), the electrodes and wiring are made of a material that transmits visible light. When the electrodes and wiring are provided at a position not overlapping with the opening of the pixel, the electrodes and wiring can be made of a material that blocks visible light. Therefore, the electrodes 181 and 182 can be made of a material with low resistivity, such as a metal. For example, it is preferable to use a metal mesh as the wiring and electrodes of the touch sensor. This can reduce the resistance of the wiring and electrodes of the touch sensor. In addition, it is suitable as a touch sensor for a large display device. In general, metal is a material with high reflectivity, but it can be made dark by performing oxidation treatment or the like. Therefore, even when viewed from the display surface side, it is possible to suppress a decrease in visibility due to reflection of external light.

[0163] The wiring and the electrodes may be formed by laminating a metal layer and a layer with low reflectance (hereinafter, referred to as a dark layer). Examples of the dark layer include a layer containing copper oxide, copper chloride or tellurium chloride. The dark layer may be formed using metal particles such as Ag particles, Ag fibers, and Cu particles, nanocarbon particles such as carbon nanotubes (CNTs) and graphene, and conductive polymers such as polyethylenedioxythiophene (PEDOT), polyaniline, and polypyrrole.

[0164] Component Materials Next, materials that can be used for each component of the display device and display module of this embodiment will be described in detail.

[0165] There is no significant limitation on the material of the substrate of the display device, and various substrates can be used, such as a glass substrate, a quartz substrate, a sapphire substrate, a semiconductor substrate, a ceramic substrate, a metal substrate, or a plastic substrate.

[0166] By using a thin substrate, the display device can be made lighter and thinner. Furthermore, by using a substrate having a sufficient thickness to provide flexibility, a flexible display device can be realized.

[0167] The transistor included in the display device of this embodiment mode may have either a top-gate type or a bottom-gate type structure, or gate electrodes may be provided above and below a channel.

[0168] The semiconductor material used for the transistor is not particularly limited, and examples thereof include metal oxides (also called oxide semiconductors) having semiconductor properties, silicon, germanium, etc. Examples of silicon include amorphous silicon and crystalline silicon (low-temperature polysilicon, single crystal silicon, etc.).

[0169] 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.

[0170] The semiconductor layer preferably contains, for example, indium, M (M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more selected from aluminum, gallium, yttrium, and tin.

[0171] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) as the semiconductor layer.

[0172] When the semiconductor layer is an In-M-Zn oxide, the sputtering target used to deposit the In-M-Zn oxide preferably has an atomic ratio of In equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such sputtering targets include In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn=2:1:3, In:M:Zn=3:1:2, In:M:Zn=4:2:3, In:M:Zn=4:2:4.1, In:M:Zn=5:1:6, In:M:Zn=5:1:7, In:M:Zn=5:1:8, In:M:Zn=6:1:6, In:M:Zn=5:2:5, and the like.

[0173] As the sputtering target, it is preferable to use a target containing a polycrystalline oxide, since it is easy to form a semiconductor layer having crystallinity. The atomic ratio of the semiconductor layer to be formed includes a variation of ±40% of the atomic ratio of the metal elements contained in the sputtering target. For example, when the composition of the sputtering target used for the semiconductor layer is In:Ga:Zn=4:2:4.1 [atomic ratio], the composition of the semiconductor layer to be formed may be close to In:Ga:Zn=4:2:3 [atomic ratio].

[0174] When the atomic ratio is described as In:Ga:Zn=4:2:3 or thereabout, this includes the case where, when the atomic ratio of In is 4, the atomic ratio of Ga is 1 or more and 3 or less, and the atomic ratio of Zn is 2 or more and 4 or less. When the atomic ratio of In is described as In:Ga:Zn=5:1:6 or thereabout, this includes the case where, when the atomic ratio of In is 5, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is 5 or more and 7 or less. When the atomic ratio of In is described as In:Ga:Zn=1:1:1 or thereabout, this includes the case where, when the atomic ratio of In is 1, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is more than 0.1 and 2 or less.

[0175] The transistors in the gate drivers GD_L and GD_R and the transistors in the display area 100 may have the same structure or different structures. The transistors in the gate drivers may all have the same structure or two or more types of structures may be combined. Similarly, the transistors in the display area 100 may all have the same structure or two or more types of structures may be combined.

[0176] Examples of insulating materials that can be used for the insulating layer of the display device include organic insulating materials and inorganic insulating materials. Examples of organic insulating materials include acrylic resins, epoxy resins, polyimide resins, polyamide resins, polyimideamide resins, siloxane resins, benzocyclobutene-based resins, and phenolic resins. Examples of inorganic insulating layers include silicon oxide films, silicon oxynitride films, silicon nitride oxide films, silicon nitride films, aluminum oxide films, hafnium oxide films, yttrium oxide films, zirconium oxide films, gallium oxide films, tantalum oxide films, magnesium oxide films, lanthanum oxide films, cerium oxide films, and neodymium oxide films.

[0177] In addition to the gate, source, and drain of a transistor, conductive layers such as various wirings and electrodes of a display device can be configured in a single layer structure or a stacked structure using one or more of metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing at least one of the metals as a main component. For example, there are a two-layer structure in which a titanium film is laminated on an aluminum film, a two-layer structure in which a titanium film is laminated on a tungsten film, a two-layer structure in which a copper film is laminated on a molybdenum film, a two-layer structure in which a copper film is laminated on an alloy film containing molybdenum and tungsten, a two-layer structure in which a copper film is laminated on a copper-magnesium-aluminum alloy film, a three-layer structure in which a titanium film or titanium nitride film is laminated on the titanium film or titanium nitride film, an aluminum film or copper film is laminated on the titanium film or titanium nitride film, and a titanium film or titanium nitride film is further formed thereon, and a three-layer structure in which a molybdenum film or molybdenum nitride film is laminated on the molybdenum film or molybdenum nitride film, an aluminum film or copper film is laminated on the molybdenum film or molybdenum nitride film, and a molybdenum film or molybdenum nitride film is further formed thereon. For example, when the conductive layer has a three-layer structure, it is preferable to form a film made of titanium, titanium nitride, molybdenum, tungsten, an alloy containing molybdenum and tungsten, an alloy containing molybdenum and zirconium, or molybdenum nitride in the first and third layers, and form a film made of a low-resistance material such as copper, aluminum, gold, silver, or an alloy of copper and manganese in the second layer. Note that a light-transmitting conductive material such as ITO, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, or ITSO may be used. Note that the oxide conductive layer may be formed by controlling the resistivity of the oxide semiconductor.

[0178] A curable resin such as a thermosetting resin, a photocurable resin, or a two-liquid mixed curable resin can be used as the adhesive layer 141. For example, an acrylic resin, a urethane resin, an epoxy resin, or a siloxane resin can be used.

[0179] The connector 139 may be, for example, an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP).

[0180] The thin films (insulating film, semiconductor film, conductive film, etc.) constituting the display device can be formed by sputtering, chemical vapor deposition (CVD), vacuum deposition, pulsed laser deposition (PLD), atomic layer deposition (ALD), etc. Examples of CVD include plasma enhanced chemical vapor deposition (PECVD) and thermal CVD. Examples of thermal CVD include metal organic CVD (MOCVD).

[0181] The thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by methods such as spin coating, dipping, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife, slit coating, roll coating, curtain coating, knife coating, etc.

[0182] The thin film constituting the display device can be processed by using a photolithography method or the like. Alternatively, an island-shaped thin film may be formed by a film formation method using a shielding mask. Alternatively, the thin film may be processed by a nanoimprint method, a sandblasting method, a lift-off method, or the like. Photolithography methods include a method in which a resist mask is formed on the thin film to be processed, the thin film is processed by etching or the like, and the resist mask is removed, and a method in which a photosensitive thin film is formed, and then the thin film is exposed to light and developed to be processed into a desired shape.

[0183] In the photolithography method, examples of the light used for exposure include i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), and a mixture of these. In addition, ultraviolet light, KrF laser light, ArF laser light, etc. can also be used. Exposure may also be performed by immersion exposure technology. Examples of the light used for exposure include extreme ultraviolet light (EUV: Extreme Ultra-violet) and X-rays. Also, an electron beam can be used instead of the light used for exposure. Extreme ultraviolet light, X-rays, or an electron beam are preferable because they enable extremely fine processing. When exposure is performed by scanning a beam such as an electron beam, a photomask is not required.

[0184] For etching the thin film, a dry etching method, a wet etching method, a sandblasting method, or the like can be used.

[0185] <Metal oxide> Metal oxides that can be used for the semiconductor layer will be described below.

[0186] In this specification and the like, metal oxides containing nitrogen may also be collectively referred to as metal oxides. Metal oxides containing nitrogen may also be referred to as metal oxynitrides. For example, metal oxides containing nitrogen, such as zinc oxynitride (ZnON), may be used for the semiconductor layer.

[0187] In this specification, etc., the term CAAC (c-axis aligned crystal) and CAC (Cloud-Aligned Composite) may be used. CAAC represents an example of a crystal structure, and CAC represents an example of a function or material configuration.

[0188] For example, a cloud-aligned composite (CAC)-OS can be used for the semiconductor layer.

[0189] 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.

[0190] 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 addition, 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.

[0191] 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 or more and 10 nm or less, preferably 0.5 nm or more and 3 nm or less.

[0192] In addition, 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. In addition, 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 in the on state of the transistor, that is, a large on-current and a high field effect mobility can be obtained.

[0193] That is, CAC-OS or CAC-metal oxide can also be called a matrix composite or a metal matrix composite.

[0194] Oxide semiconductors (metal oxides) are classified into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors, such as c-axis aligned crystalline oxide semiconductors (CAAC-OS), polycrystalline oxide semiconductors, nanocrystalline oxide semiconductors (nc-OS), amorphous-like oxide semiconductors (a-like OS), and amorphous oxide semiconductors.

[0195] 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.

[0196] Nanocrystals are basically hexagonal, but may be non-regular hexagonal. In addition, the lattice arrangement may be pentagonal or heptagonal due to the distortion. In CAAC-OS, it is difficult to confirm clear grain boundaries even in the vicinity of 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 because CAAC-OS can tolerate distortion due to the fact that the arrangement of oxygen atoms in the ab-plane direction is not dense and the bond distance between atoms changes due to the substitution of metal elements.

[0197] 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 represented as an (In, M, Zn) layer. When indium in an In layer is substituted for element M, it can also be represented as an (In, M) layer.

[0198] CAAC-OS is a metal oxide with high crystallinity. On the other hand, it is difficult to confirm clear crystal boundaries in CAAC-OS, so it is said that the decrease in electron mobility caused by crystal boundaries is unlikely to occur. In addition, since the crystallinity of metal oxides can be decreased by the inclusion of impurities or the generation of defects, CAAC-OS is unlikely to have impurities or defects (oxygen vacancies (V O : It is also called oxygen vacancy. ) Therefore, metal oxides with CAAC-OS have stable physical properties. Therefore, metal oxides with CAAC-OS are resistant to heat and highly reliable.

[0199] 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.

[0200] Indium-gallium-zinc oxide (hereinafter referred to as IGZO), a type of metal oxide containing indium, gallium, and zinc, may have a stable structure when made into the above-mentioned nanocrystals. In particular, since IGZO tends to have difficulty in crystal growth in the atmosphere, it may be structurally more stable when made into small crystals (for example, the above-mentioned nanocrystals) rather than large crystals (here, crystals of several mm or several cm).

[0201] The a-like OS is a metal oxide 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.

[0202] Oxide semiconductors (metal oxides) 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.

[0203] The metal oxide film functioning as the semiconductor layer can be formed using either one or both of an inert gas and an oxygen gas. The flow rate ratio of oxygen (oxygen partial pressure) during the formation of the metal oxide film is not particularly limited. However, in order to obtain a transistor with high field effect mobility, the flow rate ratio of oxygen (oxygen partial pressure) during the formation of the metal oxide film is preferably 0% or more and 30% or less, more preferably 5% or more and 30% or less, and even more preferably 7% or more and 15% or less.

[0204] The energy gap of the metal oxide is preferably 2 eV or more, more preferably 2.5 eV or more, and further preferably 3 eV or more. By using a metal oxide having such a wide energy gap, the off-current of the transistor can be reduced.

[0205] The metal oxide film can be formed by a sputtering method, or a PLD method, a PECVD method, a thermal CVD method, an ALD method, a vacuum deposition method, or the like.

[0206] <Display module configuration example 2> A top view of the pixel 16(i,j) is shown in Fig. 7. Fig. 7 is a top view of the laminated structure from the wiring GL1(i) to the pixel electrode 111a, as viewed from the pixel electrode 111a side.

[0207] 8 shows a cross-sectional view of the display module 52. Note that the pixel portion corresponds to the cross-sectional view taken along dashed lines G1-G2 and G3-G4 shown in FIG.

[0208] 7 and 8 differ from the configurations shown in Figures 4 and 5A in the structure of the transistors. In the following, description of parts common to the configuration examples described above may be omitted.

[0209] 7 and 8 includes a gate 221b, a gate insulating layer 211, a semiconductor layer 231b, a conductive layer 222p, a conductive layer 222q, a gate insulating layer 225, and a gate 223b. One of the conductive layer 222p and the conductive layer 222q functions as a source, and the other functions as a drain.

[0210] 7 and 8 includes a gate 221a, a gate insulating layer 211, a semiconductor layer 231a, a conductive layer 222f, a conductive layer 222g, a gate insulating layer 225, and a gate 223a. One of the conductive layer 222f and the conductive layer 222g functions as a source, and the other functions as a drain.

[0211] Each of the semiconductor layers 231a and 231b has a pair of low resistance regions 231n and a channel formation region 231i sandwiched between the pair of low resistance regions 231n.

[0212] The channel formation region 231i overlaps with the gate 221a or the gate 221b with the gate insulating layer 211 interposed therebetween, and overlaps with the gate 223a or the gate 223b with the gate insulating layer 225 interposed therebetween.

[0213] The conductive layers 222f, 222g, 222p, and 222q are formed of a material that transmits visible light. Therefore, at least a part of the external light 35 shown in FIG. 8 is transmitted through the connection portion (corresponding to the connection portion 72 in FIG. 7) between the conductive layer 222f and the conductive layer 115c, and is emitted to the outside of the display module. Similarly, the connection portion (corresponding to the connection portion 71 in FIG. 7) between the conductive layer 222p and the conductive layer 115a can also transmit visible light. This can increase the aperture ratio of the pixel, and can increase the transmittance of visible light in the display module.

[0214] As described above, in this embodiment, the case where a metal oxide is used for the semiconductor layer 231a and the semiconductor layer 231b will be described as an example.

[0215] The gate insulating layer 211 and the gate insulating layer 225 in contact with the channel formation region 231i are preferably oxide insulating layers. When the gate insulating layer 211 or the gate insulating layer 225 has a stacked structure, at least a layer in contact with the channel formation region 231i is preferably an oxide insulating layer. This can suppress oxygen vacancies in the channel formation region 231i, thereby improving the reliability of the transistor.

[0216] The insulating layer 214 is preferably a nitride insulating layer, which can prevent impurities from entering the semiconductor layers 231a and 231b and improve the reliability of the transistor.

[0217] The insulating layer 215 preferably has a planarizing function and is, for example, an organic insulating layer.

[0218] As shown in Fig. 8, the gate insulating layer 225 may overlap both the low-resistance region 231n and the channel formation region 231i. The gate insulating layer 225 shown in Fig. 8 has the advantages of being able to eliminate the step of processing the gate insulating layer 225 using the gates 223a and 223b as masks, and being able to reduce the step of the surface on which the insulating layer 214 is formed. Note that, as shown in Fig. 9, the gate insulating layer 225 may be formed only on the channel formation region 231i and may not overlap with the low-resistance region 231n.

[0219] The low-resistance region 231n has a lower resistivity than the channel formation region 231i. The low-resistance region 231n may be formed by adding impurities using the gates 223a and 223b as a mask. Examples of the impurities include hydrogen, helium, neon, argon, fluorine, nitrogen, phosphorus, arsenic, antimony, boron, aluminum, magnesium, and silicon, and the impurities can be added by ion implantation or ion doping. In addition to the above impurities, the low-resistance region 231n may be formed by adding indium, which is one of the constituent elements of the semiconductor layers 231a and 231b. By adding indium, the concentration of indium may be higher in the low-resistance region 231n than in the channel formation region 231i.

[0220] When the gate insulating layer 225 is an oxide film having a function of releasing oxygen by heating, oxygen may be supplied to the low-resistance region 231n by heating, which may reduce the carrier density and increase the electrical resistance. Therefore, it is preferable to form the low-resistance region 231n by adding impurities to a part of the semiconductor layer through the gate insulating layer 225. As a result, the impurities are also added into the gate insulating layer 225. By adding impurities to an oxide film having a function of releasing oxygen by heating, the amount of oxygen released can be reduced. Therefore, it is possible to suppress the supply of oxygen from the gate insulating layer 225 to the low-resistance region 231n by heating, and to maintain a low electrical resistance of the low-resistance region 231n.

[0221] In addition, after forming the gate insulating layer 225 and the gates 223a and 223b, a first layer is formed so as to be in contact with a portion of the semiconductor layers 231a and 231b, and a heat treatment is performed to reduce the resistance of the portion, thereby forming a low-resistance region 231n.

[0222] As the first layer, a film containing at least one of metal elements such as aluminum, titanium, tantalum, tungsten, chromium, and ruthenium can be used. In particular, it is preferable that the first layer contains at least one of aluminum, titanium, tantalum, and tungsten. Alternatively, a nitride containing at least one of these metal elements or an oxide containing at least one of these metal elements can be preferably used. In particular, a metal film such as a tungsten film or a titanium film, a nitride film such as an aluminum titanium nitride film, a titanium nitride film, or an aluminum nitride film, or an oxide film such as an aluminum titanium oxide film can be preferably used.

[0223] The thickness of the first layer can be, for example, 0.5 nm to 20 nm, preferably 0.5 nm to 15 nm, more preferably 0.5 nm to 10 nm, and even more preferably 1 nm to 6 nm. Typically, it can be about 5 nm or about 2 nm. Even if the first layer is so thin, the resistance of the semiconductor layers 231a and 231b can be sufficiently reduced.

[0224] It is important that the low-resistance region 231n has a higher carrier density than the channel formation region 231i. For example, the low-resistance region 231n can be a region that contains more hydrogen than the channel formation region 231i or a region that contains more oxygen vacancies than the channel formation region 231i. When oxygen vacancies in the oxide semiconductor are bonded to hydrogen atoms, they become a source of carrier generation.

[0225] By performing a heat treatment in a state where the first layer is provided in contact with a part of the semiconductor layers 231a and 231b, oxygen in the part is absorbed into the first layer, and many oxygen vacancies are formed in the part, so that the low resistance region 231n can be made into an extremely low resistance region.

[0226] The low-resistance region 231n thus formed has a feature that it is difficult to increase the resistance in a subsequent process. For example, even if a heat treatment or a film formation process is performed in an oxygen-containing atmosphere, the conductivity of the low-resistance region 231n is not impaired, so that a transistor having good electrical characteristics and high reliability can be realized.

[0227] When the first layer after the heat treatment has conductivity, it is preferable to remove the first layer after the heat treatment. On the other hand, when the first layer has insulation properties, the first layer can be left to function as a protective insulating film.

[0228] The FPC is electrically connected to the conductive layer 222c. Specifically, the FPC is in contact with the connector 139, the connector 139 is in contact with the conductive layer 111b, and the conductive layer 111b is in contact with the conductive layer 222c. The conductive layer 222c is formed on the insulating layer 214, and the conductive layer 111b is formed on the insulating layer 121. The conductive layer 222c can be formed in the same process and from the same material as the conductive layers 222a and 222b. The conductive layer 111b can be formed in the same process and from the same material as the pixel electrode 111a.

[0229] 9, the display device does not necessarily have to include the conductive layers 222f, 222g, 222p, and 222q (see FIGS. 7 and 8) that transmit visible light, which can simplify the manufacturing process of the display device.

[0230] 9, the conductive layer 115c and the semiconductor layer 231a (the low resistance region 231n) are in contact with each other, and the conductive layer 115a and the semiconductor layer 231b (the low resistance region 231n) are in contact with each other. For example, by using a material (such as a metal oxide) that transmits visible light for the semiconductor layers 231a and 231b, a region that transmits visible light can be provided in the contact portion between the capacitance element Cw and the transistor SW11 and in the contact portion between the liquid crystal element 110 and the transistor SW12.

[0231] In FIG. 9, the semiconductor layer 231a (the low resistance region 231n) and the conductive layer 222a that blocks visible light are in contact with each other, and the semiconductor layer 231b (the low resistance region 231n) and the conductive layer 222b that blocks visible light are in contact with each other.

[0232] 9, the low-resistance region 231n is a region of the semiconductor layers 231a and 231b that is in contact with the insulating layer 214. The insulating layer 214 preferably contains nitrogen or hydrogen. This allows the nitrogen or hydrogen in the insulating layer 214 to enter the low-resistance region 231n, thereby increasing the carrier concentration of the low-resistance region 231n.

[0233] <Display module configuration example 3> A display module 55 shown in Fig. 10 and a display module 57 shown in Fig. 11 each have a liquid crystal display device and a light emitting device stacked together. Each of the display modules 55 and 57 is configured to emit light 33 emitted from the light emitting device to the outside via the liquid crystal display device. The liquid crystal display device receives light from an edge-light type light, scatters the light in a layer containing a liquid crystal material, and emits scattered light 34 to the outside.

[0234] The configuration of the liquid crystal display device shown in FIGS. 10 and 11 is similar to that shown in FIG. 5A, and therefore a detailed description thereof will be omitted.

[0235] A display module 55 shown in Fig. 10 has a light emitting device 54. The light emitting device 54 is attached to a liquid crystal display device by an adhesive layer 169. The light emitting device 54 is a light emitting device with a top emission structure to which a color filter method is applied. The light emitting element 150 emits light toward the liquid crystal display device through a colored layer (see light 33).

[0236] The light emitting device 54 includes a substrate 161, an adhesive layer 163, an insulating layer 165, a transistor SW13, a light emitting element 150, an adhesive layer 167, an insulating layer 168, a colored layer CF1, and a colored layer CF2.

[0237] A transistor that can be used in a liquid crystal display device can be used as the transistor SW13. The transistor in the liquid crystal display device and the transistor in the light-emitting device 54 may be the same or different.

[0238] As the light-emitting element 150, it is preferable to use an EL element such as an OLED (Organic Light Emitting Diode) or a QLED (Quantum-dot Light Emitting Diode). Examples of light-emitting materials that the EL element has include a material that emits fluorescence (fluorescent material), a material that emits phosphorescence (phosphorescent material), an inorganic compound (such as a quantum dot material), and a material that exhibits thermally activated delayed fluorescence (thermally activated delayed fluorescence: TADF material). Alternatively, an LED such as a micro LED (Light Emitting Diode) can be used as the light-emitting element 150.

[0239] The light-emitting element 150 has a pixel electrode 151, an EL layer 152, and a common electrode 153. The pixel electrode 151 is electrically connected to the source or drain of the transistor SW13. The pixel electrode 151 preferably reflects visible light. An end of the pixel electrode 151 is covered with an insulating layer 155. The EL layer 152 is used in common for a plurality of sub-pixels. The EL layer 152 contains at least a light-emitting material. The common electrode 153 transmits visible light.

[0240] The light emitting device 54 has a plurality of pixels arranged in a matrix. Each pixel has one or more sub-pixels. Each sub-pixel has one light emitting element 150. For example, the pixel may have three sub-pixels (e.g., three colors of R, G, and B, or three colors of yellow (Y), cyan (C), and magenta (M)) or four sub-pixels (e.g., four colors of R, G, B, and white (W), or four colors of R, G, B, and Y).

[0241] The resolution of the light-emitting device may be the same as or different from that of the liquid crystal display device. When the resolution of the light-emitting device 54 and the liquid crystal display device are the same, one pixel (multiple sub-pixels) of the light-emitting device 54 overlaps with one pixel of the liquid crystal display device.

[0242] Light emitted by the light emitting element 150 passes through the colored layers and is emitted from the light emitting device 54. For example, light of a first color is extracted through the colored layer CF1, and light of a second color is extracted through the colored layer CF2.

[0243] The FPC 3 is electrically connected to the conductive layer 222d via a connector 139.

[0244] It is preferable to use an insulating layer with high waterproofness as the insulating layer 165 and the insulating layer 168. This can prevent impurities such as water from entering the light-emitting element 150 and improve the reliability of the light-emitting element 150. It is preferable that the insulating layer 165 and the insulating layer 168 each have an inorganic insulating film.

[0245] For the adhesive layers 163, 167, 169, various curing adhesives such as a photo-curing adhesive such as an ultraviolet curing adhesive, a reaction curing adhesive, a heat curing adhesive, and an anaerobic adhesive can be used. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. In particular, a material with low moisture permeability such as epoxy resin is preferable. A two-liquid mixed resin may also be used. An adhesive sheet or the like may also be used.

[0246] There are no significant limitations on the material of the substrate 161, and various substrates can be used, such as a glass substrate, a quartz substrate, a sapphire substrate, a semiconductor substrate, a ceramic substrate, a metal substrate, or a plastic substrate.

[0247] As the substrate 161, it is preferable to use a resin substrate such as, for example, polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. This allows the light-emitting device 54 to be made thinner and lighter.

[0248] The display module 57 shown in FIG.

[0249] The light-emitting device 56 differs from the light-emitting device 54 mainly in that it does not have the colored layer CF1, the colored layer CF2, the insulating layer 168, or the adhesive layer 169, but has the protective layer 154, and the EL layer 152 is formed separately for each subpixel. Description of the components common to the light-emitting device 54 will be omitted.

[0250] Since the EL layer 152 is formed for each subpixel, the light-emitting device 56 does not require a colored layer. Furthermore, by providing the protective layer 154 on the common electrode 153, the reliability of the light-emitting element 150 can be improved. The protective layer 154 preferably has an inorganic film with high waterproof properties.

[0251] As described above, the display device of one embodiment of the present invention has a function of adding a correction signal to an image signal, and therefore the liquid crystal element can be driven at a high voltage. Therefore, a liquid crystal element with a high driving voltage can be used for the display device. For example, even a display device using a liquid crystal element driven in a reverse mode or a liquid crystal element containing a liquid crystal material and a polymer material can display an image well.

[0252] In addition, in the display device of one embodiment of the present invention, a connection portion where a transistor and a pixel electrode are electrically connected has a function of transmitting visible light, so that the aperture ratio of a pixel can be further increased.

[0253] In addition, since the display device of one embodiment of the present invention has a function of displaying by a field sequential driving method, the aperture ratio of the pixel can be further increased. In addition, since a colored layer such as a color filter can be eliminated, the transmittance of the pixel can be increased.

[0254] The display device according to one embodiment of the present invention has a configuration suitable for use as a see-through display.

[0255] This embodiment mode can be combined with other embodiment modes as appropriate. In addition, in the case where a plurality of configuration examples are shown in one embodiment mode in this specification, the configuration examples can be combined as appropriate.

[0256] (Embodiment 2) In this embodiment, electronic devices according to one embodiment of the present invention will be described with reference to FIGS.

[0257] The electronic device of this embodiment includes the display device of one embodiment of the present invention in a display portion. Thus, the display portion of the electronic device can display high-quality images and can display images with high reliability over a wide temperature range.

[0258] The display unit of the electronic device of this embodiment can display images having resolutions of, for example, full high definition, 2K, 4K, 8K, 16K, or higher.

[0259] Examples of electronic devices in which the display device of one embodiment of the present invention can be used include electronic devices having a relatively large screen, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, audio playback devices, etc. The display device of one embodiment of the present invention can also be suitably used in portable electronic devices, wearable electronic devices, VR (Virtual Reality) devices, AR (Augmented Reality) devices, and the like.

[0260] The electronic device of one embodiment of the present invention may include a secondary battery, and it is preferable that the secondary battery be charged by using contactless power transmission.

[0261] Examples of secondary batteries include lithium ion secondary batteries such as lithium polymer batteries (lithium ion polymer batteries) that use a gel electrolyte, nickel-metal hydride batteries, nickel-cadmium batteries, organic radical batteries, lead-acid batteries, air secondary batteries, nickel-zinc batteries, and silver-zinc batteries.

[0262] The electronic device of one embodiment of the present invention may have an antenna. By receiving a signal through the antenna, images, information, and the like can be displayed on a display portion. In addition, when the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0263] An electronic device according to one embodiment of the present invention may have a sensor (including a function of measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0264] The electronic device of one embodiment of the present invention can have various functions, such as a function of displaying various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function of displaying a calendar, date, time, etc., a function of executing various software (programs), a wireless communication function, a function of reading out a program or data recorded in a recording medium, etc.

[0265] Furthermore, an electronic device having multiple display units can have a function of mainly displaying image information on one display unit and mainly displaying text information on another display unit, or a function of displaying a stereoscopic image by displaying an image taking into account parallax on the multiple display units, etc. Furthermore, an electronic device having an image receiving unit can have a function of capturing a still image or a moving image, a function of automatically or manually correcting the captured image, a function of storing the captured image in a recording medium (external or built in the electronic device), a function of displaying the captured image on the display unit, etc. Note that the functions of the electronic device of one embodiment of the present invention are not limited to these, and can have various functions.

[0266] 12A shows a television device 1810. The television device 1810 has a display unit 1811, a housing 1812, a speaker 1813, and the like. The television device 1810 may further have LED lamps, operation keys (including a power switch or an operation switch), connection terminals, various sensors, a microphone, and the like.

[0267] The television device 1810 can be operated by a remote control 1814 .

[0268] Examples of broadcast radio waves that the television device 1810 can receive include terrestrial waves and radio waves transmitted from satellites. Examples of broadcast radio waves include analog broadcasts and digital broadcasts, and also include video and audio broadcasts, or audio only broadcasts. For example, broadcast radio 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 having a resolution that exceeds full high definition on the display unit 1811. For example, images having a resolution of 4K, 8K, 16K, or higher can be displayed.

[0269] Also, an image to be displayed on the display unit 1811 may be generated using broadcast data transmitted by a data transmission technique via a computer network such as the Internet, a LAN (Local Area Network), or Wi-Fi (registered trademark). In this case, the television device 1810 does not need to have a tuner.

[0270] 12B shows a digital signage 1820 attached to a cylindrical pole 1822. The digital signage 1820 has a display unit 1821.

[0271] The larger the display unit 1821, the more information can be provided at one time. Also, the larger the display unit 1821, the more easily it catches people's attention, and the more effective the advertising, for example, can be.

[0272] Applying a touch panel to the display unit 1821 is preferable because it not only displays still images or videos on the display unit 1821 but also allows the user to intuitively operate it. Furthermore, when used for providing information such as route information or traffic information, the intuitive operation can improve usability.

[0273] 12C shows a notebook type personal computer 1830. The personal computer 1830 includes a display unit 1831, a housing 1832, a touch pad 1833, a connection port 1834, and the like.

[0274] The touch pad 1833 functions as an input means such as a pointing device or a pen tablet, and can be operated with a finger, a stylus, or the like.

[0275] A display element is also built into touchpad 1833. As shown in Fig. 12C, touchpad 1833 can be used as a keyboard by displaying input keys 1835 on the surface of touchpad 1833. In this case, a vibration module may be built into touchpad 1833 to realize a tactile sensation by vibration when input keys 1835 are touched.

[0276] An information terminal 1840 shown in FIG. 12D includes a display unit 1841, a housing 1842, a detection unit 1843, and the like.

[0277] By applying a touch panel to the display unit 1841, the information terminal 1840 can be operated using a finger, a stylus, or the like.

[0278] The detection unit 1843 may include at least one of an illuminance sensor, an imaging device, a posture detection device, a pressure sensor, and a human sensor.

[0279] 13A and 13B show a mobile information terminal 800. The mobile information terminal 800 includes a housing 801, a housing 802, a display portion 803, a display portion 804, a hinge portion 805, and the like.

[0280] Housing 801 and housing 802 are connected by hinge portion 805. Portable information terminal 800 can be opened from a folded state as shown in Fig. 13A to housing 801 and housing 802 as shown in Fig. 13B.

[0281] For example, document information can be displayed on the display portion 803 and the display portion 804, and the device can be used as an electronic book terminal.

[0282] In this way, the portable information terminal 800 can be folded when carried around, making it highly versatile.

[0283] The housing 801 and the housing 802 may each include a power button, an operation button, an external connection port, a speaker, a microphone, and the like.

[0284] An example of a portable information terminal is shown in Fig. 13C. A portable information terminal 810 shown in Fig. 13C includes a housing 811, a display unit 812, operation buttons 813, an external connection port 814, a speaker 815, a microphone 816, a camera 817, and the like.

[0285] The mobile information terminal 810 has a touch sensor on the display unit 812. Any operation, such as making a call or inputting characters, can be performed by touching the display unit 812 with a finger, a stylus, or the like.

[0286] In addition, by operating the operation button 813, it is possible to turn the power on and off, and to switch the type of image displayed on the display unit 812. For example, it is possible to switch from a mail creation screen to a main menu screen.

[0287] Furthermore, by providing a detection device such as a gyro sensor or an acceleration sensor inside the mobile information terminal 810, the orientation (portrait or landscape) of the mobile information terminal 810 can be determined and the orientation of the screen display of the display unit 812 can be automatically switched. The orientation of the screen display can also be switched by touching the display unit 812, by operating the operation button 813, or by voice input using the microphone 816.

[0288] The mobile information terminal 810 has one or more functions selected from, for example, a telephone, a notebook, or an information viewing device. Specifically, it can be used as a smartphone. The mobile information terminal 810 can execute various applications such as mobile phone, e-mail, text viewing and creation, music playback, video playback, Internet communication, and games.

[0289] 13D shows an example of a camera. The camera 820 includes a housing 821, a display unit 822, an operation button 823, a shutter button 824, and the like. In addition, the camera 820 is provided with a detachable lens 826.

[0290] Here, camera 820 is configured such that lens 826 can be removed from housing 821 and replaced, but lens 826 and the housing may be integrated together.

[0291] The camera 820 can capture still images or moving images by pressing a shutter button 824. The display unit 822 also has a function as a touch panel, and an image can also be captured by touching the display unit 822.

[0292] The camera 820 may be equipped with a strobe device, a viewfinder, and the like, or these may be built into the housing 821.

[0293] 14A shows an example in which the display device of one embodiment of the present invention is mounted as an in-vehicle display. The display unit 1100 and the display unit 1110 can provide various information by displaying navigation information, a speedometer, a tachometer, a mileage, a fuel gauge, a gear state, air conditioning settings, and the like. The display items and layout can be changed as appropriate according to the user's preference. The display device of one embodiment of the present invention can be used in a wide temperature range and can perform display with high reliability in both low-temperature and high-temperature environments. Therefore, the use of the display device of one embodiment of the present invention as an in-vehicle display can improve driving safety.

[0294] The display device of one embodiment of the present invention has a high pixel aperture ratio and a small light-blocking region, so that a view behind the display device can be seen through the display device. Therefore, the display device of one embodiment of the present invention can be used as a windshield of a car, a window of a building, a show window, an augmented reality (AR) device, and the like.

[0295] 14B shows an example in which the display device of one embodiment of the present invention is used in a window of a building. The display device 1200 may be provided over the entire window, or the display device 1200 may be provided in a part of the window, and glass may be used in the other part. The display device 1200 can display an image 1210 facing indoors or outdoors. When the image 1210 is not displayed on the display device 1200, the display device 1200 transmits light, so that one side of the room and the other side can be seen through the display device 1200. In other words, the display device 1200 can be treated like conventional window glass.

[0296] FIG. 14C shows an example in which the display device of one embodiment of the present invention is used in a case for a show window. The display device 1300 may be provided on the entire surface of the case, or the display device 1300 may be provided on a portion of the surface and glass may be used on the remaining portion. The display device 1300 can display an image 1310 facing the outside of the case. An example of the image 1310 is an image (ribbon in FIG. 14C) that decorates a decorated object 1320 (such as a product, a bag in FIG. 14C) on the inside of the case. The image 1310 may also include a description of the product or a promotional text.

[0297] As described above, an electronic device can be obtained by applying the display device of one embodiment of the present invention. The display device has a very wide range of application and can be applied to electronic devices in a variety of fields.

[0298] This embodiment mode can be combined with other embodiment modes as appropriate. [Explanation of symbols]

[0299] CF1: colored layer, CF2: colored layer, CSCOM: wiring, GL1: wiring, GL2: wiring, SL1: wiring, SL2: wiring, SW11: transistor, SW12: transistor, SW13: transistor, VCOM: wiring, 10: display device, 11: touch panel, 15: pixel, 16: pixel, 30: light unit, 32: light, 33: light, 34: scattered light, 35: external light, 50: display module, 51: display module, 52: display module, 54: light-emitting device, 55: display module, 56: light-emitting device, 57: display module, 71: connection section, 72: connection section, 10 0: display region, 110: liquid crystal element, 111a: pixel electrode, 111b: conductive layer, 112: layer containing liquid crystal material, 113: common electrode, 114a: alignment film, 114b: alignment film, 115a: conductive layer, 115b: conductive layer, 115c: conductive layer, 120: pixel circuit, 121: insulating layer, 131: substrate, 132: substrate, 139: connector, 141: adhesive layer, 150: light emitting element, 151: pixel electrode, 152: EL layer, 153: common electrode, 154: protective layer, 155: insulating layer, 161: substrate, 163: adhesive layer, 165: insulating layer, 167: adhesive layer, 168: insulating layer, 169: adhesive layer, 1 80: substrate, 181: electrode, 182: electrode, 185: insulating layer, 186: adhesive layer, 187: wiring, 188: conductive layer, 189: connector, 211: gate insulating layer, 213: insulating layer, 214: insulating layer, 215: insulating layer, 221a: gate, 221b: gate, 221c: conductive layer, 221m: gate, 221n: gate, 221s: gate, 221t: gate, 221u: gate, 222a: conductive layer, 222b: conductive layer, 222c: conductive layer, 222d: conductive layer, 222e: conductive layer, 222f: conductive layer, 222g: conductive layer, 222m: conductive layer, 222n: conductive layer, 2 22p: conductive layer, 222q: conductive layer, 222s: conductive layer, 222t: conductive layer, 222u: conductive layer, 223a: gate, 223b: gate, 223m: gate, 223n: gate, 223s: gate, 223t: gate, 223u: gate, 225: gate insulating layer, 231a: semiconductor layer, 231b: semiconductor layer, 231i: channel formation region, 231n: low resistance region, 800: portable information terminal, 801: housing, 802: housing, 803: display unit, 804: display unit, 805: hinge unit, 810: portable information terminal, 811: housing, 812: display unit, 813: operation button,814: external connection port, 815: speaker, 816: microphone, 817: camera, 820: camera, 821: housing, 822: display unit, 823: operation button, 824: shutter button, 826: lens, 1100: display unit, 1110: display unit, 1200: display device, 1210: image, 1300: display device, 1310: image, 1320: decorated object, 1810: television device, 18 11: display unit, 1812: housing, 1813: speaker, 1814: remote control operation device, 1820: digital signage, 1821: display unit, 1822: pillar, 1830: personal computer, 1831: display unit, 1832: housing, 1833: touch pad, 1834: connection port, 1835: input key, 1840: information terminal, 1841: display unit, 1842: housing, 1843: detection unit,

Claims

[Claim 1] having a pixel, The pixel includes a first transistor electrically connected to a first gate line, a second transistor electrically connected to a second gate line, a first insulating layer, a second insulating layer, a first conductive layer, a pixel electrode, a layer including a liquid crystal material, and a common electrode; the first insulating layer has a region located over a channel formation region of the first transistor and a region located over a channel formation region of the second transistor; the first conductive layer is located on the first insulating layer; the second insulating layer has a region located on the first transistor, a region located on the second transistor, a region located on the first insulating layer, and a region located on the first conductive layer; the pixel electrode has a region located on the second insulating layer and a region overlapping the first conductive layer via the second insulating layer; the layer including the liquid crystal material is located on the pixel electrodes; the common electrode is located on the layer including the liquid crystal material; the common electrode has a region overlapping with the first conductive layer with the layer containing a liquid crystal material and the pixel electrode interposed therebetween; The pixel further includes a first connection portion and a second connection portion, the first conductive layer is electrically connected to the first transistor in the first connection portion; the pixel electrode is electrically connected to the second transistor at the second connection portion; In a plan view of the pixel, a region where the first conductive layer and the pixel electrode overlap does not have a region where the first conductive layer and the pixel electrode overlap with either a source electrode or a drain electrode of the first transistor or a source electrode or a drain electrode of the second transistor; In the plan view, the pixel electrode does not have a region overlapping with the first connection portion, The display device, wherein the first conductive layer, the pixel electrode, and the common electrode each have a function of transmitting visible light.

Images