Display device

Abstract

To provide a display device with an imaging function, and provide an imaging device or a display device of high definition.SOLUTION: A display device includes first to fourth switches, a first transistor, a capacitor, and a light receiving and emitting element. The first switch is connected to a gate of the first transistor. The second switch is connected to one of a source and a drain of the first transistor. The light receiving and emitting element has an anode connected to the other of the source and the drain of the first transistor through the third switch. The fourth switch is connected to the other of the source and the drain of the first transistor. The capacitor has one electrode connected to the gate of the first transistor and the other electrode connected to the other of the source and the drain of the first transistor. The light receiving and emitting element emits light with a first color, receives light with a second color, and converts the light into electric signals.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION One aspect of the present invention relates to a display device, an imaging device, and a display device having an imaging function.

[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 disclosed in this specification and the like include semiconductor devices, display devices, light-emitting devices, power storage devices, memory devices, electronic devices, lighting devices, input devices, input / output devices, driving methods thereof, and manufacturing methods thereof. A semiconductor device refers to any device that can function by utilizing semiconductor characteristics. [Background technology]

[0003] In recent years, display devices have been required to have higher resolution in order to display high-resolution images. Furthermore, for information terminal devices such as smartphones, tablet devices, and notebook PCs (personal computers), display devices are required to have not only high resolution but also low power consumption. Furthermore, there is a demand for display devices that not only display images but also have various additional functions, such as touch panel functionality and the ability to capture fingerprints for authentication.

[0004] As a display device, for example, a light-emitting device having a light-emitting element has been developed. Light-emitting elements (also referred to as EL elements) that utilize the electroluminescence (hereinafter referred to as EL) phenomenon have features such as being easily made thin and lightweight, being capable of responding quickly to input signals, and being able to be driven using a DC constant voltage power supply, and are therefore applied to display devices. For example, Patent Document 1 discloses a flexible light-emitting device that uses an organic EL element. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-197522 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of one embodiment of the present invention is to provide a display device having an imaging function.An object of one embodiment of the present invention is to provide an imaging device or a display device having a high-definition display portion or an imaging portion.An object of one embodiment of the present invention is to provide an imaging device or a display device that can capture high-definition images.An object of one embodiment of the present invention is to provide an imaging device or a display device that can capture images with high sensitivity.An object of one embodiment of the present invention is to provide a display device that can acquire biometric information such as a fingerprint.An object of one embodiment of the present invention is to provide a display device that functions as a touch panel.

[0007] Another object of one embodiment of the present invention is to reduce the number of components in an electronic device.Another object of one embodiment of the present invention is to provide a display device, an imaging device, an electronic device, or the like having a novel structure.Another object of one embodiment of the present invention is to alleviate at least one of the problems of the prior art.

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

[0009] One embodiment of the present invention is a display device including first to third switches, a first transistor, a capacitor, a light-emitting / receiving element, and first to third wirings. The first wiring is electrically connected to a gate of the first transistor through the first switch. The second wiring is electrically connected to one of the source and drain of the first transistor through the second switch. The light-emitting / receiving element has an anode electrically connected to the other of the source and drain of the first transistor through the third switch and a cathode electrically connected to the third wiring. The capacitor has one electrode electrically connected to the gate of the first transistor and the other electrode electrically connected to the other of the source and drain of the first transistor. A first potential is applied to the second wiring and a second potential lower than the first potential is applied to the third wiring. The light-emitting / receiving element has a function of emitting light of a first color and a function of receiving light of a second color and converting it into an electrical signal.

[0010] One embodiment of the present invention is a display device including first to fourth switches, a first transistor, a capacitor, a light-emitting / receiving element, and first to fourth wirings. The first wiring is electrically connected to a gate of the first transistor through the first switch. The second wiring is electrically connected to one of a source and a drain of the first transistor through the second switch. The light-emitting / receiving element has an anode electrically connected to the other of the source and the drain of the first transistor through a third switch and a cathode electrically connected to the third wiring. The fourth wiring is electrically connected to the other of the source and the drain of the first transistor through the fourth switch. The capacitor has one electrode electrically connected to the gate of the first transistor and the other electrode electrically connected to the other of the source and the drain of the first transistor. A first potential is applied to the second wiring, and a second potential lower than the first potential is applied to the third wiring. The light emitting / receiving element has a function of emitting light of a first color and a function of receiving light of a second color and converting it into an electrical signal.

[0011] In the above, it is preferable that the first to fourth switches are in a conductive state, a data potential is applied to the first wiring, and a third potential is applied to the fourth wiring during the first period, and that the first to fourth switches are in a non-conductive state during the second period.

[0012] In any of the above, during the third period, it is preferable that the first switch, the third switch, and the fourth switch are in a conductive state, the second switch is in a non-conductive state, a fourth potential lower than the first potential is applied to the first wiring, and a fifth potential lower than the second potential is applied to the fourth wiring. Furthermore, during the fourth period, it is preferable that the first switch and the third switch are in a conductive state, the second switch and the fourth switch are in a non-conductive state, and a sixth potential higher than the second potential is applied to the first wiring. Furthermore, during the fifth period, it is preferable that the first switch and the third switch are in a non-conductive state, and the second switch and the fourth switch are in a conductive state.

[0013] Another embodiment of the present invention is a display device including first to fifth transistors, a capacitor, a light-emitting / receiving element, and first to fourth wirings. One of the source and drain of the second transistor is electrically connected to the first wiring, and the other of the source and drain is electrically connected to the gate of the first transistor. One of the source and drain of the third transistor is electrically connected to the second wiring, and the other of the source and drain is electrically connected to the one of the source and drain of the first transistor. One of the source and drain of the fourth transistor is electrically connected to the other of the source and drain of the first transistor, and the other of the source and drain is electrically connected to the anode of the light-emitting / receiving element. A cathode of the light-emitting / receiving element is electrically connected to the third wiring. One of the source and drain of the fifth transistor is electrically connected to the other of the source and drain of the first transistor, and the other of the source and drain is electrically connected to the fourth wiring. The capacitor has one electrode electrically connected to the gate of the first transistor and the other electrode electrically connected to the other of the source and drain of the first transistor. A first potential is applied to the second wiring, and a second potential lower than the first potential is applied to the third wiring. The light emitting / receiving element has a function of emitting light of a first color and a function of receiving light of a second color and converting it into an electrical signal.

[0014] In the above, it is preferable that at least one of the first to fifth transistors has a gate and a back gate, and the same potential is applied to the gate and the back gate.

[0015] In the above, it is preferable to have a light-emitting element that has a function of emitting light of the second color, and in this case, it is more preferable that the light-emitting / receiving element and the light-emitting element are provided on the same surface.

[0016] In the above, the light emitting / receiving element preferably has a first pixel electrode, a first light emitting layer, an active layer, and a first electrode. The light emitting element preferably has a second pixel electrode, a second light emitting layer, and a first electrode. In this case, the first pixel electrode and the second pixel electrode are preferably formed by processing the same conductive film.

[0017] Another embodiment of the present invention is a display module including any one of the display devices described above and a connector or an integrated circuit.

[0018] Another embodiment of the present invention is an electronic device including the above-described display module and at least one of an antenna, a battery, a housing, a camera, a speaker, a microphone, a touch sensor, and an operation button. [Effects of the Invention]

[0019] According to one embodiment of the present invention, a display device having an imaging function can be provided. Alternatively, an imaging device or display device having a display unit or an imaging unit can be provided. Alternatively, an imaging device or display device capable of capturing high-resolution images can be provided. Alternatively, an imaging device or display device capable of capturing high-sensitivity images can be provided. Alternatively, a display device capable of acquiring biometric information such as a fingerprint can be provided. Alternatively, a display device functioning as a touch panel can be provided.

[0020] According to one aspect of the present invention, the number of components in an electronic device can be reduced, or a display device, an imaging device, or an electronic device having a novel configuration can be provided, or at least one of the problems of the prior art can be alleviated.

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

[0022] [Figure 1] FIG. 1 is a circuit diagram showing an example of a pixel. [Figure 2] 2A and 2B are diagrams illustrating an example of a method for operating a pixel circuit. [Figure 3] 3A to 3D are diagrams illustrating an example of a method for operating a pixel circuit. [Figure 4] Fig. 4A is a circuit diagram showing an example of a pixel, and Fig. 4B and Fig. 4C are diagrams for explaining an example of a method of operating the pixel circuit. [Figure 5] 5A to 5E are diagrams illustrating an example of a method for operating a pixel circuit. [Figure 6] FIG. 6 is a diagram illustrating an example of a display device. [Figure 7] FIG. 7 is a circuit diagram showing an example of a pixel. [Figure 8] FIG. 8A is a circuit diagram showing an example of a pixel, and FIG. 8B is a circuit diagram of a transistor. [Figure 9] FIG. 9 is a circuit diagram showing an example of a pixel. [Figure 10] 10A and 10B are diagrams showing an example of a display device. [Figure 11] FIG. 11 is a circuit diagram showing an example of a pixel. [Figure 12] FIG. 12 is a diagram illustrating an example of a method of operating the display device. [Figure 13] FIG. 13 is a diagram illustrating an example of a method of operating the display device. [Figure 14] 14A to 14D are cross-sectional views showing an example of a display device, and Fig. 14E to 14G are top views showing an example of a pixel. [Figure 15] 15A to 15D are top views showing examples of pixels. [Figure 16] 16A to 16E are cross-sectional views showing examples of light emitting and receiving elements. [Figure 17] 17A and 17B are cross-sectional views showing an example of a display device. [Figure 18] 18A and 18B are cross-sectional views showing an example of a display device. [Figure 19] 19A and 19B are cross-sectional views showing an example of a display device. [Figure 20] 20A and 20B are cross-sectional views showing an example of a display device. [Figure 21] 21A and 21B are cross-sectional views showing an example of a display device. [Figure 22] FIG. 22 is a perspective view showing an example of a display device. [Figure 23] FIG. 23 is a cross-sectional view showing an example of a display device. [Figure 24] FIG. 24 is a cross-sectional view showing an example of a display device. [Figure 25] 25A is a cross-sectional view showing an example of a display device, and FIG 25B is a cross-sectional view showing an example of a transistor. [Figure 26] 26A and 26B are diagrams showing an example of an electronic device. [Figure 27] 27A to 27D are diagrams showing examples of electronic devices. [Figure 28] 28A to 28F are diagrams showing examples of electronic devices. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments will be described with reference to the drawings. However, it will be readily understood by those skilled in the art that the embodiments can be implemented in many different ways and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the following description of the embodiments.

[0024] 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 repeated explanations thereof will be omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0025] In the drawings described in this specification, the size of each component, the thickness of a layer, or an area may be exaggerated for clarity, and therefore, the drawings are not necessarily limited to the scale.

[0026] In this specification, ordinal numbers such as "first" and "second" are used to avoid confusion of components and do not limit the number.

[0027] A transistor is a type of semiconductor element that can perform switching operations such as amplifying current or voltage and controlling conduction or non-conduction. In this specification, the term "transistor" includes an IGFET (Insulated Gate Field Effect Transistor) and a TFT (Thin Film Transistor).

[0028] Furthermore, the functions of "source" and "drain" may be interchangeable when transistors of different polarities are used, or when the direction of current flow changes during circuit operation, etc. For this reason, the terms "source" and "drain" may be used interchangeably in this specification.

[0029] Furthermore, in this specification, "electrically connected" includes connection via "something that has some kind of electrical action." Here, "something that has some kind of electrical action" is not particularly limited as long as it allows electrical signals to be transmitted and received between the connected objects. For example, "something that has some kind of electrical action" includes electrodes, wiring, switching elements such as transistors, resistive elements, coils, capacitive elements, and other elements with various functions.

[0030] In this specification, a node refers to an element (for example, a wiring) that allows electrical connection of elements that make up a circuit. Therefore, a "node to which A is connected" refers to a wiring that is electrically connected to A and can be considered to have the same potential as A. Even if one or more elements (for example, a switch, transistor, capacitance element, inductor, resistance element, diode, etc.) that allow electrical connection are placed along the wiring, the wiring is considered to be a node to which A is connected as long as it can be considered to have the same potential as A.

[0031] In this specification, the EL layer refers to a layer provided between a pair of electrodes of a light-emitting element and containing at least a light-emitting substance (also referred to as a light-emitting layer), or a stack including a light-emitting layer.

[0032] In this specification and the like, a display panel, which is one aspect of a display device, has a function of displaying (outputting) images etc. on a display surface, and therefore the display panel is one aspect of an output device.

[0033] In addition, in this specification, a display panel having a connector such as an FPC (Flexible Printed Circuit) or TCP (Tape Carrier Package) attached to the substrate, or having an IC mounted on the substrate using a COG (Chip On Glass) method or the like, may be referred to as a display panel module, display module, or simply a display panel.

[0034] In this specification and the like, a touch panel, which is one aspect of a display device, has a function of displaying an image or the like on a display surface and a function as a touch sensor that detects that a detectable object such as a finger or a stylus touches, presses, or approaches the display surface. Thus, the touch panel is one aspect of an input / output device.

[0035] A touch panel can also be called, for example, a display panel (or display device) with a touch sensor or a display panel (or display device) with a touch sensor function. A touch panel can have a configuration including a display panel and a touch sensor panel. Alternatively, the touch panel can have a touch sensor function inside or on the surface of the display panel.

[0036] In addition, in this specification and the like, a touch panel substrate on which a connector, an IC, etc. are mounted may be called a touch panel module, a display module, or simply a touch panel.

[0037] (Embodiment 1) In this embodiment, a structural example of a display device according to one embodiment of the present invention and an example of a driving method thereof will be described.

[0038] One embodiment of the present invention is a display device having a plurality of pixels arranged in a matrix, each of which has one or more sub-pixels, and each of which has one or more light-emitting and light-emitting elements.

[0039] A light-emitting / receiving element (light-emitting / receiving device) is an element that has both the function of a light-emitting element (also called a light-emitting device) that emits light of a first color and the function of a photoelectric conversion element (also called a photoelectric conversion device) that receives light of a second color and converts it into an electrical signal. A light-emitting / receiving element can also be called a multifunctional element, multifunctional diode, light-emitting photodiode, bidirectional photodiode, etc.

[0040] By arranging a plurality of sub-pixels, each having a light receiving / emitting element, in a matrix, the display device can have both the function of displaying an image and the function of capturing an image, and therefore the display device can also be called a composite device or a multi-function device.

[0041] [Configuration example 1] 1 shows a portion of a pixel circuit that can be applied to a subpixel having a light emitting / receiving element. The pixel circuit includes switches SW1, SW2, SW3, SW4, a transistor Tr1, and a light emitting / receiving element SA. The pixel circuit preferably includes a capacitor CS for holding electric charge. The pixel circuit is also connected to wirings SL, AL, CL, and WX.

[0042] The switches SW1, SW2, SW3, and SW4 each have two terminals (electrodes) and are elements that can control the conduction and non-conduction between the terminals.

[0043] The wiring SL is electrically connected to the gate of the transistor Tr1 via the switch SW1. The wiring AL is electrically connected to one of the source and drain of the transistor Tr1 via the switch SW2. The anode of the light emitting / receiving element SA is electrically connected to the other of the source and drain of the transistor Tr1 via the switch SW3. The cathode of the light emitting / receiving element SA is electrically connected to the wiring CL. The wiring WX is electrically connected to the other of the source and drain of the transistor Tr1 via the switch SW4. The capacitor CS has one of a pair of electrodes electrically connected to the gate of the transistor Tr1 and the other electrically connected to the other of the source and drain of the transistor Tr1.

[0044] 1, the anode of the light emitting element SA is located on the transistor Tr1 side. In this case, the potential applied to the wiring CL can be lower than the potential applied to the wiring AL. Note that the cathode of the light emitting element SA may be located on the transistor Tr1 side, in which case the potential applied to the wiring CL can be higher than the potential applied to the wiring AL.

[0045] 1 and the like show examples in which n-channel transistors are used as the transistors, p-channel transistors can also be used for some or all of the transistors. In this case, various potentials, signals, and the like can be changed as appropriate depending on the type of transistor.

[0046] The transistor Tr1 has a function of controlling the current flowing through the light emitting / receiving element SA. That is, the transistor Tr1 functions as a drive transistor. The transistor Tr1 can control the current flowing through the light emitting / receiving element SA in accordance with the potential (data potential) applied from the line SL via the switch SW1. The light emitting / receiving element SA can emit light with a brightness corresponding to the current.

[0047] The transistor Tr1 also functions as a readout transistor, outputting a signal based on the exposure state of the light-emitting element SA. Specifically, a predetermined potential is applied to the gate of the transistor Tr1, and a potential based on the charge generated by the light-emitting element SA when it receives light is applied to the source, causing the conductivity state of the transistor Tr1 to change according to the voltage between the gate and source. Information on the exposure state of the light-emitting element SA can be obtained from the current flowing from the wiring AL to the wiring WX via the transistor Tr1. The wiring WX also functions as a readout wiring.

[0048] In this way, by using a single transistor Tr1 to act as both a drive transistor when the light-receiving / light-emitting element SA is used as a light-emitting element and a readout transistor when the light-receiving / light-emitting element SA is used as a light-receiving element, the circuit configuration of the pixel circuit can be simplified. Furthermore, by eliminating one transistor, the wiring for supplying signals to the transistor can also be reduced.

[0049] Furthermore, the capacitance CS not only functions as a storage capacitance when the light emitting / receiving element SA is used as a light emitting element, but also functions as a storage capacitance when used as a light receiving element.

[0050] In this way, by configuring the transistor and the capacitor to have multiple functions, it is possible to reduce the area occupied by the pixel and realize a display device with high resolution, which not only enables high-quality images to be displayed but also enables high-resolution images to be captured.

[0051] The operation method of the pixel circuit illustrated in FIG. 1 will now be described.

[0052] First, an example of an operation method when the light emitting / receiving element SA is used as a light emitting element will be described with reference to FIGS. 2A and 2B.

[0053] FIG. 2A shows a case where a data potential V data 10A and 10B show the operation during a data write period (data write period). During the data write period, the switches SW1, SW2, SW3, and SW4 are all in a conductive state.

[0054] During the data write period, as shown by one dashed arrow, the gate of the transistor Tr1 is supplied with a data potential V data As shown by the other dashed arrow, the other of the source and drain of the transistor Tr1 is supplied with a potential V0 from the wiring WX via the switch SW4. At this time, the capacitor CS1 is supplied with a data potential V data A voltage corresponding to the potential difference between potential V0 and potential V1 is charged.

[0055] 2B shows a schematic diagram of the operation during the period (holding and light-emitting periods) in which the gate potential of transistor Tr1 is held and the light-emitting element SA emits light in response to the current flowing through transistor Tr1. During the holding and light-emitting periods, switches SW1 and SW4 are turned off, and switches SW2 and SW3 are turned on. This causes almost all of the current flowing through transistor Tr1 to flow to the light-emitting element SA. In FIG. 2B, the current path is indicated by dashed arrows.

[0056] Next, an example of an operation method when the light emitting / receiving element SA is used as a light receiving element will be described with reference to FIGS. 3A to 3D.

[0057] 3A shows a schematic diagram of the operation during a period (reset period) in which the potential of the anode of the light emitting / receiving element SA is initialized. During the reset period, the switches SW1, SW3, and SW4 are in a conductive state, and the switch SW2 is in a non-conductive state.

[0058] During the reset period, as shown by one of the dashed arrows, the anode of the light emitting element SA is supplied with a potential V RS The other electrode of the capacitor CS is also supplied with a potential V RS is given. The potential V RS The potential V is at least lower than the potential applied to the wiring CL. RS is preferably set to a potential lower than the potential V0.

[0059] In addition, when the cathode of the light emitting element SA is connected to the transistor Tr1 side, the potential V RS The potential V may be set to a potential higher than the potential applied to the wiring CL (the potential applied to the anode of the light emitting element SA). RS may be set to a potential higher than the potential V0.

[0060] In addition, during the reset period, it is preferable that the node to which the gate of the transistor Tr1 is connected is not in a floating state but is in a state in which a predetermined potential is applied. For example, in FIG. 3A, the gate of the transistor Tr1 and one electrode of the capacitor CS are connected to a potential V off is given. The potential V off may be set to a potential lower than the potential applied to the wiring AL.

[0061] Also, the potential V off It is preferable that the potential V be set to a potential that makes the transistor Tr1 non-conductive. RSThe potential V can be set to a potential lower than the potential obtained by adding the threshold voltage of the transistor Tr1 to the potential V off is the potential V RS It is preferable that the potential is lower than

[0062] 3B shows a schematic diagram of the operation during a period (exposure period) in which the light receiving / emitting element SA receives light and accumulates charge in the light receiving / emitting element SA. During the exposure period, the accumulation of charge in the light receiving / emitting element SA changes the potential difference Vc between the anode and cathode of the light receiving / emitting element SA.

[0063] During the exposure period, the switches SW1, SW2, SW3, and SW4 are all in a non-conductive state. When the switch SW2 is in a non-conductive state, the gate of the transistor Tr1 is supplied with a potential V off Since the state in which the signal is applied is maintained, the transistor Tr1 also becomes non-conductive. Furthermore, since the switch SW3 is non-conductive, there are two non-conductive switches and one non-conductive transistor between the wiring AL and the light emitting / receiving element SA. Furthermore, there are two non-conductive switches (switch SW3 and switch SW4) between the wiring WX and the light emitting / receiving element SA. This makes it possible to effectively prevent the charge accumulated on the anode side of the light emitting / receiving element SA from leaking out to the wiring AL, wiring WX, etc. As a result, the light emitting / receiving element SA can perform highly accurate imaging.

[0064] 3C shows a schematic diagram of the operation during a period (transfer period) in which the charge accumulated in the light emitting / receiving element SA is transferred to the node connected to the source of the transistor Tr1. During the transfer period, the switches SW1 and SW3 are in a conductive state, and the switches SW2 and SW4 are in a non-conductive state.

[0065] During the transfer period, as shown by one of the dashed arrows, the charge stored in the light emitting / receiving element SA is transferred via the switch SW3 to the node to which the source of the transistor Tr1 and the other electrode of the capacitor CS are connected. The potential of this node when the transfer is completed is V sigLet's say.

[0066] During the transfer period, as shown by the other dashed arrow, the node to which the gate of the transistor Tr1 and one electrode of the capacitor CS are connected is supplied with a potential V gp is given.

[0067] After the charging of the capacitor CS is completed, the switches SW1 and SW3 are turned off, thereby maintaining the gate potential and source potential of the transistor Tr1.

[0068] 3D shows a schematic diagram of the operation during a period (readout period) when data is output from the pixel circuit to the line WX. During the readout period, the switches SW1 and SW3 are in a non-conductive state, and the switches SW2 and SW4 are in a conductive state.

[0069] During the read period, the gate-source voltage V of the transistor Tr1 gs (shown by the dotted arrow) is the potential V gp and potential V sig Using V gs =V gp -V sig The gate-source voltage V of transistor Tr1 gs Therefore, the current flowing through the transistor Tr1 is also determined. For example, in the saturated region, the voltage V gs to the threshold voltage V of transistor Tr1 th Current I proportional to the square of the voltage minus S flows between the source and drain of the transistor Tr1.

[0070] Potential V gp is the potential V sig That is, the potential V sig Regardless of the value of V gs -V th The potential V gp You can set the value of

[0071] In this way, by using a single transistor to function as both a drive transistor for display and a readout transistor for imaging, it is possible to reduce not only the number of transistors in the pixel circuit but also the wiring connected to the pixel circuit, thereby simplifying the pixel circuit. This makes it easier to achieve higher definition and higher resolution in the display device. Furthermore, the reduction in the number of wirings also reduces the power consumption of the display device.

[0072] [Variations] Below, an example of a pixel circuit configuration in which the number of elements is further reduced compared to the configuration exemplified above will be described.

[0073] Fig. 4A shows a part of a pixel circuit. The pixel circuit shown in Fig. 4A includes a switch SW1, a switch SW2, a switch SW3, a transistor Tr1, a capacitor CS, and a light emitting / receiving element SA. The pixel circuit shown in Fig. 4A differs from the configuration shown in Fig. 1 mainly in that it does not include a switch SW4 and a wiring WX.

[0074] The wiring AL also functions as the wiring WX. That is, the wiring AL is connected to the anode potential and the potential V RS and are applied for different periods. The wiring AL also functions as a read wiring.

[0075] The operation method of the pixel circuit shown in FIG. 4A will now be described.

[0076] First, the case where the light emitting / receiving element SA is used as a light emitting element will be described.

[0077] 4B, the switches SW1, SW2, and SW3 are all turned on, so that the data potential V data is given.

[0078] 4C, in the hold and light-emitting period, the switch SW1 is turned off, causing a current corresponding to the gate potential of the transistor Tr1 to flow through the light-emitting element SA, and the light-emitting element SA emits light with a luminance corresponding to the magnitude of the current.

[0079] Next, a case where the light emitting / receiving element SA is used as a light receiving element will be described.

[0080] 5A, the switches SW1, SW2, and SW3 are all turned on. The gate of the transistor Tr1 is connected to a potential V H The wiring AL is also given a potential V RS is given.

[0081] Potential V H is the potential that turns on the transistor Tr1. H For example, the potential V RS or a potential higher than the potential (cathode potential) applied to the wiring CL.

[0082] When the transistor Tr1 is turned on, the anode of the light emitting element SA is supplied with a potential V RS is given.

[0083] After the reset period, an operation period as shown in FIG. 5B may be provided.

[0084] Specifically, in FIG. 5B, after the reset period, the switch SW3 is turned off, and the wiring SL and the wiring AL are respectively supplied with a potential V H This gives the same potential V to the pair of electrodes of the capacitance CS. H is applied, and no potential difference occurs. Similarly, no potential difference occurs between the source and gate of transistor Tr1. If the threshold voltage of transistor Tr1 is positive, transistor Tr1 becomes non-conductive.

[0085] In this way, by discharging the capacitance CS after the reset period and leaving it in a state where no charge is stored, noise in the imaging data can be reduced.

[0086] Subsequently, during the exposure period shown in FIG. 5C, the switches SW1, SW2, and SW3 are set to a non-conductive state.

[0087] 5D, the switch SW2 is kept in a non-conductive state, and the switches SW1 and SW3 are both turned on. As a result, the potential V gp After the transfer, the potential of the other of the source and drain of the transistor Tr1 and the other electrode of the capacitor CS is the potential V sig This becomes:

[0088] After the transfer period, the switches SW1 and SW3 may be set to a non-conductive state until the read period begins.

[0089] Finally, in the read period shown in FIG. 5E, the switch SW1 is turned off, and the switches SW2 and SW3 are turned on. Here, the capacitance CS is connected to the voltage V gs is charged, the transistor Tr1 is charged to the voltage V gs Current I according to S This current I S is detected by a readout circuit connected to the wiring AL, whereby pixel data can be read out.

[0090] The above is a description of the modified example.

[0091] [Configuration example 2] [Display Device Configuration Example 1] A more specific example of the structure of the display device of one embodiment of the present invention will be described below.

[0092] 6 is a block diagram illustrating the configuration of the display device 10. The display device 10 includes a display unit 11, a drive circuit unit 12, a drive circuit unit 13, a drive circuit unit 14, a circuit unit 15, and the like.

[0093] The display unit 11 has a plurality of pixels 30 arranged in a matrix. Each pixel 30 has sub-pixels 20R, 20G, and 20B. The sub-pixel 20R has a light emitting / receiving element, and the sub-pixels 20G and 20B each have a light emitting element.

[0094] The subpixel 20R is electrically connected to the line SL1, the line GL, the line SE, the line WX, etc. The subpixel 20G is electrically connected to the line SL2, the line GL, etc. The subpixel 20B is electrically connected to the line SL3, the line GL, etc.

[0095] The wiring SL1, the wiring SL2, and the wiring SL3 are each electrically connected to a driving circuit unit 12. The wiring GL is electrically connected to a driving circuit unit 13. The driving circuit unit 12 functions as a source line driving circuit (also referred to as a source driver) and supplies data signals (data potentials) to each subpixel via the wirings SL1, SL2, and SL3. The driving circuit unit 13 functions as a gate line driving circuit (also referred to as a gate driver) and supplies a selection signal to the wiring GL.

[0096] The wiring SE is electrically connected to the drive circuit unit 14. The drive circuit unit 14 has a function of generating signals to be supplied to the subpixel 20R and outputting them to the wiring SE, etc. The drive circuit unit 14 also has a function of generating and outputting signals to be supplied to wirings AEN, REN, etc., which will be described later. Note that the drive circuit unit 13 or the drive circuit unit 12 may have a function of generating signals to be supplied to wirings AEN, REN, etc.

[0097] The wiring WX is electrically connected to the circuit unit 15. The circuit unit 15 has a function of receiving a signal output from the subpixel 20R via the wiring WX and outputting it to the outside as imaging data. The circuit unit 15 functions as a readout circuit. The circuit unit 15 also has a function of generating and outputting a signal to be supplied to the wiring WX. Therefore, the circuit unit 15 also has a function as a drive circuit. Note that the drive circuit unit 13 or the drive circuit unit 12 may have a function of generating and outputting a signal to be supplied to the wiring WX.

[0098] [Pixel configuration example] 7 shows an example of a circuit diagram of pixel 30. Pixel 30 has subpixels 20R, 20G, and 20B. Subpixel 20R has a circuit 21R and a light-emitting element SR. Subpixel 20G has a circuit 21G and a light-emitting element ELG. Subpixel 20B has a circuit 21B and a light-emitting element ELB.

[0099] The circuit 21R includes a transistor M1, a transistor M2, a transistor M4, a transistor M5, a transistor M6, a capacitor C1, and the like.

[0100] The circuit 21R functions as a circuit for controlling the light emission of the light emitting element SR when the light emitting element SR is used as a light emitting element. The circuit 21R has a function of controlling the current flowing through the light emitting element SR in accordance with the data potential applied from the wiring SL1.

[0101] Furthermore, when the light emitting element SR is used as a light receiving element, the circuit 21R functions as a sensor circuit for controlling the operation of the light emitting element SR. The circuit 21R has functions such as applying a reverse bias voltage to the light emitting element SR, controlling the exposure period of the light emitting element SR, holding a potential based on the charge transferred from the light emitting element SR, and outputting a signal based on the potential to the wiring WX.

[0102] The subpixel 20R shown in Fig. 7 corresponds to the configuration illustrated in Fig. 1. The transistor M2 corresponds to the transistor Tr1 in Fig. 1. Similarly, the transistor M1 corresponds to the switch SW1, the transistor M4 corresponds to the switch SW2, the transistor M5 corresponds to the switch SW3, and the transistor M6 corresponds to the switch SW4.

[0103] The transistor M1 has a gate electrically connected to a wiring GL, one of its source and drain electrically connected to a wiring SL1, and the other electrically connected to the gate of the transistor M2 and one electrode of the capacitor C1. The transistor M2 has one of its source and drain electrically connected to the other of the source and drain of the transistor M4, and the other electrically connected to one of the source and drain of the transistor M5, one of the source and drain of the transistor M6, and the other electrode of the capacitor C1. The transistor M4 has a gate electrically connected to a wiring AEN, and one of its source and drain electrically connected to a wiring AL. The transistor M5 has a gate electrically connected to a wiring REN, and the other of its source and drain electrically connected to the anode of the light-emitting element SR. The transistor M6 has a gate electrically connected to a wiring SE, and the other of its source and drain electrically connected to a wiring WX. The light-emitting element SR has a cathode electrically connected to a wiring CL.

[0104] The wiring SL1 is supplied with a data potential V data , potential V off , potential V gp The wiring AL is supplied with an anode potential, and the wiring CL is supplied with a cathode potential. In the configuration shown in FIG. 7, the anode potential is higher than the cathode potential. The wiring WX is supplied with a potential V0 and a potential V RS The wiring WX functions as a readout line. The wirings AEN, REN, GL, and SE are supplied with signals that control the conduction and non-conduction of the transistors M4, M5, M1, and M6, respectively.

[0105] The transistor M6 functions as a selection transistor for reading. The transistor M6 is controlled to be conductive or non-conductive by a signal applied to the wiring SE. By making the transistors M6 and M4 conductive, the transistor M2 and the wiring WX are conductive, and the gate-source voltage V of the transistor M2 is gs A current (or voltage) according to the voltage can be output to the wiring WX.

[0106] The subpixel 20G has a circuit 21G and a light-emitting element ELG. The subpixel 20B has a circuit 21B and a light-emitting element ELB. The circuits 21G and 21B have the same configuration.

[0107] The circuit 21G and the circuit 21B each include a transistor M1, a transistor M2, a transistor M3, and a capacitor C1. The transistor M3 has a gate electrically connected to a wiring GL, one of a source and a drain electrically connected to the other electrode of the capacitor C1, the other of the source and drain of the transistor M2, and the anode of the light-emitting element ELG or the light-emitting element ELB, and the other electrically connected to a wiring V0L.

[0108] A constant potential is applied to the wiring V0L. For example, the same potential as the potential V0 applied to the wiring WX may be applied to the wiring V0L. Alternatively, the wiring WX may be used instead of the wiring V0L.

[0109] Here, the difference in the number of transistors between the circuit 21R and the circuit 21G or 21B is only two. As described above, in one embodiment of the present invention, a circuit that can cause a light-emitting element to function as both a light-emitting element and a light-receiving element can be configured by adding only two transistors to a circuit that drives a light-emitting element. Therefore, an increase in the area occupied by the circuit 21R can be suppressed, and a display device with high pixel density can be realized.

[0110] It is preferable to use transistors with extremely low leakage current in a non-conducting state as the transistors M1, M3, M4, M5, and M6, which function as switches. In particular, a transistor using an oxide semiconductor for a semiconductor layer in which a channel is formed can be suitably used. It is also preferable to use a transistor using an oxide semiconductor for the transistor M2, because all the transistors can be formed through a common manufacturing process. Silicon (including amorphous silicon, polycrystalline silicon, and single crystal silicon) may be used for the semiconductor layer in which the channel is formed in the transistor M2. However, this is not a limitation, and transistors using silicon may be used for some or all of the transistors. Furthermore, transistors using inorganic semiconductors, compound semiconductors, organic semiconductors, or the like other than silicon may be used for some or all of the transistors.

[0111] Furthermore, as shown in Fig. 8A, a transistor having a back gate may be used for each transistor, in which a pair of gates are electrically connected.

[0112] Note that, in FIG. 8A, all transistors have a pair of gates electrically connected, but this is not limiting. The pixel 30 may have a transistor having one gate connected to another wiring. For example, connecting one of the pair of gates to a wiring to which a constant potential is applied can improve the stability of electrical characteristics. Alternatively, one of the pair of gates may be connected to a wiring to which a potential for controlling the threshold voltage of the transistor is applied. Alternatively, as shown in FIG. 8B, a transistor may be used in which one of the pair of gates is connected to one of the source and drain. In this case, it is preferable to connect one of the gates to the source. For example, the transistors shown in FIG. 8B can be suitably used as the transistors M2 and M4 in the pixel 30.

[0113] Although an example in which all the transistors have a back gate has been shown here, the present invention is not limited to this, and transistors with a back gate and transistors without a back gate may be mixed.

[0114] [Modification] An example of a pixel configuration that is partially different from the above will be described below.

[0115] A circuit diagram of a pixel 30A, which will be exemplified below, is shown in Fig. 9. The configuration example shown in Fig. 9 is different from that shown in Fig. 7 in the configurations of a circuit 21R, a circuit 21G, and a circuit 21B.

[0116] The circuit 21R is obtained by omitting the transistor M6, the wiring WX, and the wiring SE from the circuit 21R illustrated in Fig. 7. The circuit 21R corresponds to the configuration illustrated in Fig. 4A.

[0117] 7. The circuit 21G does not include the transistor M3 and the wiring V0L. The same is true for the circuit 21B.

[0118] This configuration allows for a further reduction in the number of transistors and wiring. Specifically, three transistors and four wirings are reduced compared to the configuration shown in Figure 7. This configuration allows for even higher resolution and a higher aperture ratio.

[0119] The above is a description of the modified example.

[0120] [Display Device Configuration Example 2] While the example in which one pixel has three sub-pixels has been described above, the following will describe an example in which one pixel has two sub-pixels.

[0121] Fig. 10A shows an example of an arrangement method for 3 x 3 pixels, showing pixels from the i-th row and j-th column (i and j are each independently an integer of 1 or greater) to the i+2-th row and j+2-th column.

[0122] 10A, pixels 30G and 30B are arranged alternately in the row and column directions. Pixel 30G includes subpixels 20R and 20G. Pixel 30B includes subpixels 20R and 20B.

[0123] For example, pixel 30G located in the i-th row and j-th column is connected to wiring GL[i] and wiring SE[i] extending in the row direction, and wiring SL1[j], wiring SL2[j], and wiring WX[j] extending in the column direction.

[0124] 10B shows an example of an arrangement method of the light-emitting / receiving elements SR, the light-emitting elements ELG, and the light-emitting elements ELB. The light-emitting / receiving elements SR are arranged at equal intervals in the row and column directions. The light-emitting elements ELG and the light-emitting elements ELB are arranged alternately in the row and column directions. The light-emitting / receiving elements SR, the light-emitting elements ELG, and the light-emitting elements ELB each have a square shape tilted at approximately 45 degrees with respect to the arrangement direction. This allows for a large distance between adjacent elements, and allows for good production yield when separately manufacturing light-emitting elements and light-emitting / receiving elements.

[0125] [Drive method example] An example of a method for driving a display device will be described below.

[0126] Here, the configuration in which one pixel has three sub-pixels, as illustrated in Fig. 6, will be described as an example. A more specific configuration is shown in Fig. 11. Fig. 11 shows a circuit diagram of two pixels 30 adjacent in the column direction. Here, the circuit diagram shows two rows of pixels 30, the i-th row and j-th column and the i+1-th row and j-th column.

[0127] In the following description, the display device is assumed to have a display unit having a plurality of pixels arranged in a matrix of M rows and N columns (M and N are each independently an integer of 2 or more).

[0128] 12 and 13 are schematic diagrams showing the operation of a display device. The operation of a display device can be broadly divided into a period (display period) during which an image is displayed using light-emitting and light-emitting elements, and a period (imaging period) during which an image is captured using light-emitting and light-receiving elements (also called sensors). The display period is a period during which image data is written to pixels and a display based on the image data is performed. The imaging period is a period during which an image is captured by the light-emitting and light-receiving elements and the captured image data is read out.

[0129] First, the operation during the display period will be described with reference to FIG.

[0130] During the display period, data is repeatedly written to the pixels. During this period, the sensor does not operate (referred to as blank). Note that imaging can also be performed during the display period.

[0131] One write operation writes one frame of image data. As shown in Figure 12, one write operation (denoted as "write") writes data to pixels sequentially from the first column to the Mth column.

[0132] 12 shows a timing chart of the data writing operation for the i-th row and the i+1-th row. The timing chart shows the transition of potentials in the wirings GL[i], GL[i+1], SE[i], SE[i+1], AEN, REN, WX, SL1[j], SL2[j], and SL3[j]. Regarding the connection relationship between each wiring and each pixel, see FIGS. 6 and 11.

[0133] In the writing period of the i-th row, a high-level potential is applied to the wiring GL[i], the wiring SE[i], the wiring AEN, and the wiring REN. A potential V0 is applied to the wiring WX. A data potential D R [i,j] applies a data potential D G [i,j] applies a data potential D B [i,j] are given respectively.

[0134] Similarly to the above, writing to the (i+1)th row and thereafter can be performed row by row by applying a high-level potential to the corresponding wiring GL and wiring SE and applying a data potential to the wiring SL1, wiring SL2, and wiring SL3.

[0135] By performing this write operation from row 1 to row M, data writing for one frame is completed. During the display period, the above operation is repeated to display a moving image.

[0136] Next, the operation during the imaging period will be described with reference to Fig. 13. Here, the imaging operation using the global shutter method will be described. Note that the driving method is not limited to the global shutter method, and a rolling shutter method can also be applied.

[0137] The imaging period is divided into a period in which imaging is performed simultaneously in each pixel (referred to as imaging; hereinafter, to distinguish it from the imaging period, it is also referred to as imaging operation period) and a period in which imaging data is read out sequentially (referred to as readout). The imaging operation period is divided into an initialization period, an exposure period, and a transfer period. Furthermore, during the readout period, imaging data is read out row by row from the 1st row to the Mth row.

[0138] 13 shows a timing chart for the imaging operation period and the readout period. Here, the transition of potentials is shown for the wiring GL[1:M], wiring SE[i], wiring SE[i+1], wiring AEN, wiring REN, wiring SL1[1:N], wiring SL2[1:N], wiring SL3[1:N], and wiring WX[1:N]. Here, the wirings GL are collectively referred to as wiring GL[1:M], and the wirings WX are collectively referred to as wiring WX[1:N]. Similarly, the wirings SL1, SL2, and SL3 are collectively referred to.

[0139] During the initialization period, a low-level potential is applied to the line AEN, which causes the transistor M4 to be non-conductive in all subpixels 20R, thereby electrically insulating the light emitting element SR from the line AL and preventing the light emitting element SR from unintentionally emitting light.

[0140] In addition, a high-level potential is applied to all the lines GL, all the lines SE, and the line REN. This causes the transistors M1, M5, and M6 in the subpixel 20R to be in a conductive state. Then, a potential V off Applying a potential V to all wiring WX RS As a result, the reset operation is performed in all the sub-pixels 20R.

[0141] Here, the wiring SL2 and the wiring SL3 are supplied with a data potential D G or data potential D B This allows one or both of the light emitting elements ELG and ELB to emit light and be used as a light source when capturing an image.

[0142] Subsequently, during the exposure period, a low level potential is applied to the lines GL, SE, and REN, causing charges to be accumulated in the light emitting / receiving elements SR according to the amount of light irradiated thereto.

[0143] Subsequently, in the transfer period, a high-level potential is applied to the line GL and the line REN. This causes the transistors M1 and M5 to be conductive in the subpixel 20R. At this time, the charge accumulated in the light emitting / receiving element SR can be transferred to the node to which the source of the transistor M2 is connected. Furthermore, the node to which the gate of the transistor M2 is connected receives a potential V from the line SL1 via the transistor M1. gp After that, a low-level potential is applied to the wiring GL and the wiring REN, so that the potentials of the two nodes are maintained.

[0144] Next, the image data is read out row by row. During the readout period, a high-level potential is applied to the wiring AEN. Furthermore, during the readout period, a high-level potential is applied in order from the wiring SE[1] to the wiring SE[N], so that data can be read out for all pixels. For example, in the readout of the i-th row, a high-level potential is applied to the wiring SE[i], so that the data D of the i-th row is applied to the wiring WX[1:N]. W Specifically, data D in the i-th row and j-th column is output to one wiring WX[j]. W [i,j] is output.

[0145] During the exposure period and the readout period, a low level potential is applied to all the wirings GL, and the transistor M1 is in a non-conductive state. As a result, the gate of the transistor M2 is supplied with a potential V gp is applied and maintained. Therefore, imaging with reduced noise can be performed. Note that, since the transistor M1 is off at this time, the potential applied to the wiring SL1 does not matter (represented as "don't care"). Similarly, the potentials applied to the wirings SL2 and SL3 do not matter.

[0146] Although an example in which one data item is output by reading one row has been shown here, two data items may be output and correlated double sampling (CDS) may be performed using these two output data items. By performing CDS, the effects of variations in the electrical characteristics of each pixel can be reduced.

[0147] For example, during a read period of one row, a high-level potential is applied to the wiring GL and a predetermined potential is applied from the wiring SL1, so that the second data can be output to the wiring WX.

[0148] The above is a description of an example of the driving method.

[0149] At least a part of the configuration examples exemplified in this embodiment and the corresponding drawings can be combined as appropriate with other configuration examples or drawings.

[0150] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0151] (Embodiment 2) In this embodiment, a display device according to one embodiment of the present invention will be described.

[0152] A display device according to one embodiment of the present invention includes a light-emitting element and a light-emitting and receiving element.

[0153] The light-receiving and light-emitting element can be fabricated by combining an organic EL element, which is a light-emitting element, with an organic photodiode, which is a light-receiving element. For example, the light-receiving and light-emitting element can be fabricated by adding an active layer of an organic photodiode to the layered structure of the organic EL element. Furthermore, the light-receiving and light-emitting element fabricated by combining an organic EL element and an organic photodiode can suppress an increase in the number of film formation steps by simultaneously forming layers that can be configured in common with the light-emitting element.

[0154] For example, one of the pair of electrodes (common electrode) can be a layer common to the light-emitting and receiving elements and the light-emitting element. It is also preferable that at least one of the hole injection layer, hole transport layer, electron transport layer, and electron injection layer be a layer common to the light-emitting and receiving elements and the light-emitting element. Furthermore, the light-emitting and receiving elements and the light-emitting element can have the same configuration, except for the presence or absence of an active layer of the light-receiving element. In other words, the light-emitting and receiving elements can be fabricated simply by adding the active layer of the light-receiving element to the light-emitting element. Having a common layer between the light-emitting and receiving elements and the light-emitting element in this way can reduce the number of film formations and masks, thereby reducing the manufacturing process and manufacturing costs of the display device. Furthermore, a display device having a light-emitting and receiving element can be fabricated using existing display device manufacturing equipment and manufacturing methods.

[0155] Note that the layers of the light-emitting / receiving element may have different functions when the light-emitting / receiving element functions as a light-receiving element and when it functions as a light-emitting element. In this specification, components are named based on their functions when the light-emitting / receiving element functions as a light-emitting element. For example, a hole injection layer functions as a hole injection layer when the light-emitting / receiving element functions as a light-emitting element, and functions as a hole transport layer when the light-emitting / receiving element functions as a light-receiving element. Similarly, an electron injection layer functions as an electron injection layer when the light-emitting / receiving element functions as a light-emitting element, and functions as an electron transport layer when the light-emitting / receiving element functions as a light-receiving element.

[0156] As described above, the display device of this embodiment has a light-emitting / receiving element and a light-emitting element in a display portion. Specifically, the light-emitting / receiving element and the light-emitting element are arranged in a matrix in the display portion. Therefore, the display portion has one or both of an imaging function and a sensing function in addition to a function of displaying an image.

[0157] The display unit can be used as an image sensor, a touch sensor, or the like. That is, by detecting light in the display unit, it is possible to capture an image, detect the approach or contact of an object (a finger, a pen, or the like), and the like. Furthermore, in the display device of this embodiment, the light-emitting element can be used as a light source for the sensor. Therefore, it is not necessary to provide a light-receiving unit and a light source separately from the display device, and the number of components in the electronic device can be reduced.

[0158] In the display device of this embodiment, when an object reflects the light emitted from the light-emitting element of the display unit, the light-receiving and light-emitting element can detect the reflected light, so that imaging, touch (contact or approach) detection, and the like are possible even in dark places.

[0159] The display device of this embodiment mode has a function of displaying an image using a light-emitting element and a light-emitting / light-emitting element. That is, the light-emitting element and the light-emitting / light-emitting element function as display elements.

[0160] As the light-emitting element, 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). Furthermore, an LED such as a micro LED (Light Emitting Diode) can also be used as the light-emitting element.

[0161] The display device of this embodiment has a function of detecting light using a light receiving and emitting element, which can detect light having a shorter wavelength than light emitted by the light receiving and emitting element itself.

[0162] When the light emitting / receiving elements are used in an image sensor, the display device of this embodiment can capture an image using the light emitting / receiving elements. For example, the display device of this embodiment can be used as a scanner.

[0163] For example, data such as fingerprints and palm prints can be acquired using an image sensor. That is, a biometric authentication sensor can be built into the display device of the present embodiment. By building a biometric authentication sensor into the display device, the number of components in the electronic device can be reduced compared to when a biometric authentication sensor is provided separately from the display device, and the electronic device can be made smaller and lighter.

[0164] In addition, an image sensor can be used to acquire data such as the user's facial expression, eye movement, or changes in pupil diameter. By analyzing this data, it is possible to acquire information about the user's mind and body. By changing the display and / or audio output content based on this information, it is possible to ensure the user's safe use of devices, for example, for virtual reality (VR), augmented reality (AR), or mixed reality (MR).

[0165] Furthermore, when the light emitting and receiving elements are used as a touch sensor, the display device of this embodiment can detect the approach or contact of an object by using the light emitting and receiving elements.

[0166] The light emitting / receiving element functions as a photoelectric conversion element that detects light incident on the light emitting / receiving element and generates electric charges. The amount of electric charges generated is determined based on the amount of incident light.

[0167] The light emitting / receiving element can be fabricated by adding an active layer of a light receiving element to the above-described light emitting element configuration.

[0168] The light emitting / receiving element may be, for example, an active layer of a pn-type or pin-type photodiode.

[0169] In particular, it is preferable to use an organic photodiode active layer having a layer containing an organic compound as the light-receiving / light-emitting element. Organic photodiodes can be easily made thin, lightweight, and large in area, and have a high degree of freedom in shape and design, making them applicable to a variety of display devices.

[0170] 14A to 14D show cross-sectional views of display devices according to embodiments of the present invention.

[0171] A display device 350A shown in FIG. 14A includes, between a substrate 351 and a substrate 359, a layer 353 having a light emitting / receiving element and a layer 357 having a light emitting element.

[0172] A display device 350B shown in FIG. 14B includes, between a substrate 351 and a substrate 359, a layer 353 having a light emitting / receiving element, a layer 355 having a transistor, and a layer 357 having a light emitting element.

[0173] The display devices 350A and 350B have a structure in which green (G) light and blue (B) light are emitted from the layer 357 having the light-emitting elements, and red (R) light is emitted from the layer 353 having the light-emitting and light-emitting elements. Note that in the display device of one embodiment of the present invention, the color of light emitted from the layer 353 having the light-emitting and light-emitting elements is not limited to red.

[0174] The light emitting / receiving elements included in the layer 353 having the light emitting / receiving elements can detect light incident from outside the display device 350A or the display device 350B. The light emitting / receiving elements can detect, for example, one or both of green (G) light and blue (B) light.

[0175] A display device according to one embodiment of the present invention has a plurality of pixels arranged in a matrix. Each pixel has one or more subpixels. Each subpixel has one light-emitting / receiving element or one light-emitting element. For example, a pixel may have three subpixels (e.g., three colors of R, G, and B, or three colors of yellow (Y), cyan (C), and magenta (M)) or four subpixels (e.g., four colors of R, G, B, and white (W), or four colors of R, G, B, and Y). At least one subpixel of one color has a light-emitting / receiving element. The light-emitting / receiving element may be provided in all or some of the pixels. Furthermore, one pixel may have multiple light-emitting / receiving elements.

[0176] The layer 355 having transistors includes, for example, a transistor electrically connected to a light-emitting / receiving element and a transistor electrically connected to a light-emitting element. The layer 355 having transistors may further include wirings, electrodes, terminals, capacitors, resistors, and the like.

[0177] The display device of one embodiment of the present invention may have a function to detect an object such as a finger in contact with the display device (FIG. 14C). Alternatively, it may have a function to detect an object approaching (not in contact with) the display device (FIG. 14D). For example, as shown in FIGS. 14C and 14D, light emitted from a light-emitting element in a layer 357 having a light-emitting element is reflected by a finger 352 that has come into contact with or approached the display device 350B, and the reflected light is detected by a light-emitting element in a layer 353 having a light-emitting element. This makes it possible to detect that the finger 352 has come into contact with or approached the display device 350B.

[0178] [Pixels] 14E to 14G and 15A to 15D show examples of pixels. Note that the arrangement of the subpixels is not limited to the order shown in the drawings. For example, the positions of the subpixels 311B and 311G may be reversed.

[0179] 14E is a stripe array. The pixel has a subpixel 311SR that emits red light and has a light-receiving function, a subpixel 311G that emits green light, and a subpixel 311B that emits blue light. In a display device in which a pixel is composed of three subpixels, R, G, and B, by replacing the light-emitting element used in the R subpixel with a light-receiving / light-emitting element, a display device in which the pixel has a light-receiving function can be manufactured.

[0180] 14F is a matrix array. The pixel has subpixel 311SR that emits red light and has a light-receiving function, subpixel 311G that emits green light, subpixel 311B that emits blue light, and subpixel 311W that emits white light. Even in a display device where a pixel is composed of four subpixels, R, G, B, and W, by replacing the light-emitting element used in the R subpixel with a light-receiving / light-emitting element, a display device in which the pixel has a light-receiving function can be manufactured.

[0181] The pixels shown in FIG. 14G are arranged in a Pentile array. In FIG. 14G, each pixel has subpixels that emit two different colors of light. The upper left pixel and lower right pixel shown in FIG. 14G have a subpixel 311SR that emits red light and has a light-receiving function, and a subpixel 311G that emits green light. The lower left pixel and upper right pixel shown in FIG. 14G have a subpixel 311G that emits green light, and a subpixel 311B that emits blue light. The shapes of the subpixels shown in FIG. 14G indicate the top shapes of the light-emitting or light-receiving elements of the subpixels.

[0182] 15A includes a subpixel 311SR that emits red light and has a light-receiving function, a subpixel 311G that emits green light, and a subpixel 311B that emits blue light. The subpixel 311SR is arranged in a column different from the subpixels 311G and 311B. The subpixels 311G and 311B are arranged alternately in the same column, with one being arranged in an odd-numbered row and the other being arranged in an even-numbered row. Note that the subpixels arranged in a column different from the subpixels of other colors are not limited to red (R) and may be green (G) or blue (B).

[0183] FIG. 15B shows two pixels, each consisting of three subpixels surrounded by dotted lines. The pixel shown in FIG. 15B has a subpixel 311SR that emits red light and has a light-receiving function, a subpixel 311G that emits green light, and a subpixel 311B that emits blue light. In the pixel on the left shown in FIG. 15B, the subpixel 311G is arranged in the same row as the subpixel 311SR, and the subpixel 311B is arranged in the same column as the subpixel 311SR. In the pixel on the right shown in FIG. 15B, the subpixel 311G is arranged in the same row as the subpixel 311SR, and the subpixel 311B is arranged in the same column as the subpixel 311G. In the pixel layout shown in FIG. 15B, the subpixels 311SR, 311G, and 311B are arranged repeatedly in both odd-numbered and even-numbered rows, and in each column, subpixels of different colors are arranged in the odd-numbered and even-numbered rows.

[0184] Figure 15C is a modification of the pixel array shown in Figure 14G. The upper left pixel and lower right pixel shown in Figure 15C have a sub-pixel 311SR that emits red light and has a light-receiving function, and a sub-pixel 311G that emits green light. The lower left pixel and upper right pixel shown in Figure 15C have a sub-pixel 311SR that emits red light and has a light-receiving function, and a sub-pixel 311B that emits blue light.

[0185] In FIG. 14G, each pixel is provided with a sub-pixel 311G that emits green light. On the other hand, in FIG. 15C, each pixel is provided with a sub-pixel 311SR that emits red light and has a light-receiving function. Because each pixel is provided with a sub-pixel that has a light-receiving function, the configuration shown in FIG. 15C can capture images with higher resolution than the configuration shown in FIG. 14G. This can, for example, improve the accuracy of biometric authentication.

[0186] Furthermore, the top surface shapes of the light-emitting element and light-receiving / light-emitting element are not particularly limited and may be circular, elliptical, polygonal, polygonal with rounded corners, etc. Fig. 14G shows an example of a circular top surface shape of the light-emitting element of the subpixel 311G, and Fig. 15C shows an example of a square top surface shape. The top surface shapes of the light-emitting element and light-receiving / light-emitting element for each color may be different from each other, or may be the same for some or all of the colors.

[0187] The aperture ratios of the subpixels of each color may be different from each other, or may be the same for some or all of the colors. For example, the aperture ratio of the subpixel provided in each pixel (subpixel 311G in FIG. 14G, subpixel 311SR in FIG. 15C) may be smaller than the aperture ratios of the subpixels of other colors.

[0188] Fig. 15D is a modified example of the pixel array shown in Fig. 15C. Specifically, the configuration in Fig. 15D is obtained by rotating the configuration in Fig. 15C by 45°. In Fig. 15C, it has been described that one pixel is made up of two sub-pixels, but as shown in Fig. 15D, it can also be understood that one pixel is made up of four sub-pixels.

[0189] In FIG. 15D, one pixel is described as being composed of four subpixels surrounded by dotted lines. One pixel has two subpixels 311SR, one subpixel 311G, and one subpixel 311B. By having one pixel have multiple subpixels with a light receiving function, it is possible to capture images with high resolution. This can improve the accuracy of biometric authentication. For example, the resolution of the image can be set to the root double of the resolution of the display.

[0190] A display device to which the configuration shown in Figure 15C or Figure 15D is applied has p (p is an integer of 2 or more) first light-emitting elements, q (q is an integer of 2 or more) second light-emitting elements, and r (r is an integer greater than p and greater than q) light-receiving and light-emitting elements. p and r satisfy r = 2p. Furthermore, p, q, and r satisfy r = p + q. One of the first light-emitting elements and the second light-emitting element emits green light, and the other emits blue light. The light-receiving and light-emitting element emits red light and has a light-receiving function.

[0191] For example, when touch detection is performed using a light-emitting / receiving element, it is preferable that the light emitted from the light source is difficult for the user to see. Because blue light is less visible than green light, it is preferable that a light-emitting element that emits blue light be used as the light source. Therefore, it is preferable that the light-emitting / receiving element has a function of receiving blue light and converting it into an electrical signal.

[0192] As described above, pixels with various arrangements can be applied to the display device of one embodiment of the present invention.

[0193] In the display device of this embodiment, there is no need to change the pixel arrangement in order to incorporate a light-receiving function into the pixel, and therefore, one or both of an imaging function and a sensing function can be added to the display portion without reducing the aperture ratio and the resolution.

[0194] [Light emitting / receiving element] 16A to 16E show examples of the layered structure of the light emitting and receiving element.

[0195] The light emitting / receiving element has at least an active layer and a light emitting layer between a pair of electrodes.

[0196] The light-emitting / receiving element may further include a layer containing a substance with high hole-injecting property, a substance with high hole-transporting property, a substance with high hole-blocking property, a substance with high electron-transporting property, a substance with high electron-injecting property, a substance with high electron-blocking property, or a bipolar substance (a substance with high electron-transporting property and high hole-transporting property), as a layer other than the active layer and the light-emitting layer.

[0197] 16A to 16C each have a first electrode 180, a hole injection layer 181, a hole transport layer 182, an active layer 183, a light-emitting layer 193, an electron transport layer 184, an electron injection layer 185, and a second electrode 189.

[0198] 16A to 16C can be considered to have a configuration in which an active layer 183 is added to a light-emitting element. Therefore, by simply adding a step of forming the active layer 183 to the manufacturing process of the light-emitting element, the light-emitting / receiving element can be formed in parallel with the formation of the light-emitting element. Furthermore, the light-emitting element and the light-emitting / receiving element can be formed on the same substrate. Therefore, it is possible to provide the display unit with either or both of an imaging function and a sensing function without significantly increasing the number of manufacturing steps.

[0199] The stacking order of the light-emitting layer 193 and the active layer 183 is not limited. Fig. 16A shows an example in which the active layer 183 is provided on the hole transport layer 182, and the light-emitting layer 193 is provided on the active layer 183. Fig. 16B shows an example in which the light-emitting layer 193 is provided on the hole transport layer 182, and the active layer 183 is provided on the light-emitting layer 193. The active layer 183 and the light-emitting layer 193 may be in contact with each other, as shown in Figs. 16A and 16B.

[0200] As shown in Fig. 16C, it is preferable that a buffer layer is sandwiched between the active layer 183 and the light-emitting layer 193. The buffer layer can be at least one layer selected from the group consisting of a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a hole blocking layer, and an electron blocking layer. Fig. 16C shows an example in which a hole transport layer 182 is used as the buffer layer.

[0201] By providing a buffer layer between the active layer 183 and the light-emitting layer 193, it is possible to suppress the transfer of excitation energy from the light-emitting layer 193 to the active layer 183. In addition, the buffer layer can also be used to adjust the optical path length (cavity length) of the microresonance (microcavity) structure. Therefore, a light-emitting / receiving element having a buffer layer between the active layer 183 and the light-emitting layer 193 can obtain high light-emitting efficiency.

[0202] 16A and 16C in that it does not have the hole transport layer 182. The light emitting / receiving element may not have at least one layer selected from the hole injection layer 181, the hole transport layer 182, the electron transport layer 184, and the electron injection layer 185. The light emitting / receiving element may also have other functional layers such as a hole blocking layer and an electron blocking layer.

[0203] The light emitting / receiving device shown in FIG. 16E differs from the light emitting / receiving device shown in FIGS. 16A to 16C in that it does not have active layer 183 and light emitting layer 193, but has layer 186 that serves as both a light emitting layer and an active layer.

[0204] The layer 186 serving as both the light-emitting layer and the active layer may be, for example, a layer containing three materials: an n-type semiconductor that can be used for the active layer 183, a p-type semiconductor that can be used for the active layer 183, and a light-emitting substance that can be used for the light-emitting layer 193.

[0205] It is preferable that the lowest energy absorption band in the absorption spectrum of the mixed material of n-type and p-type semiconductors does not overlap with the maximum peak in the emission spectrum (PL spectrum) of the luminescent substance, and it is more preferable that they are sufficiently separated from each other.

[0206] In the light emitting / receiving element, a conductive film that transmits visible light is used for the electrode on the light extraction side, and a conductive film that reflects visible light is preferably used for the electrode on the non-light extraction side.

[0207] When the light emitting / receiving element is operated as a light emitting element, the hole injection layer is a layer that injects holes from the anode into the hole transport layer. The hole injection layer is a layer containing a material with high hole injection properties. As the material with high hole injection properties, a composite material containing a hole transport material and an acceptor material (electron accepting material), an aromatic amine compound (a compound having an aromatic amine skeleton), or the like can be used.

[0208] When the light emitting / receiving element is operated as a light emitting element, the hole transport layer is a layer that transports holes injected from the anode by the hole injection layer to the light emitting layer. When the light emitting / receiving element is operated as a light receiving element, the hole transport layer is a layer that transports holes generated in the active layer based on incident light to the anode. The hole transport layer is a layer that contains a hole transport material. The hole transport material is a material having a concentration of 1×10 -6 cm 2 A material having a hole mobility of 1 / Vs or more is preferred. Note that other materials can also be used as long as they have a higher hole transporting property than electron transporting property. As the hole transporting material, a material having a high hole transporting property, such as a π-electron-rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, a furan derivative, etc.) or an aromatic amine compound, is preferred.

[0209] When the light emitting / receiving element is operated as a light emitting element, the electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer to the light emitting layer. When the light emitting / receiving element is operated as a light receiving element, the electron transport layer is a layer that transports electrons generated in the active layer based on incident light to the cathode. The electron transport layer is a layer that contains an electron transporting material. The electron transporting material is a material containing 1×10 -6 cm 2A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than holes. Examples of electron-transporting materials that can be used include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0210] When the light emitting / receiving element is operated as a light emitting element, the electron injection layer is a layer that injects electrons from the cathode to the electron transport layer. The electron injection layer is a layer containing a material with high electron injection properties. As the material with high electron injection properties, alkali metals, alkaline earth metals, or compounds thereof can be used. As the material with high electron injection properties, a composite material containing an electron transport material and a donor material (electron donor material) can also be used.

[0211] The light-emitting layer 193 is a layer containing a light-emitting substance. The light-emitting layer 193 can contain one or more types of light-emitting substances. As the light-emitting substance, a substance that emits light of a color such as blue, purple, blue-purple, green, yellow-green, yellow, orange, or red is appropriately used. Furthermore, as the light-emitting substance, a substance that emits near-infrared light can also be used.

[0212] Examples of light-emitting materials include fluorescent materials, phosphorescent materials, TADF materials, and quantum dot materials.

[0213] Examples of fluorescent materials include pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives.

[0214] Examples of phosphorescent materials include organometallic complexes (particularly iridium complexes) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine skeleton; organometallic complexes (particularly iridium complexes) having a phenylpyridine derivative having an electron-withdrawing group as a ligand; platinum complexes; and rare earth metal complexes.

[0215] The light-emitting layer 193 may contain one or more organic compounds (host materials, assist materials, etc.) in addition to a light-emitting substance (guest material). As the one or more organic compounds, one or both of a hole-transporting material and an electron-transporting material can be used. Furthermore, as the one or more organic compounds, a bipolar material or a TADF material can be used.

[0216] The light-emitting layer 193 preferably includes, for example, a phosphorescent material and a hole-transporting material and an electron-transporting material that are a combination that easily forms an exciplex. This structure allows efficient emission using Exciplex-Triplet Energy Transfer (ExTET), which is energy transfer from an exciplex to a light-emitting substance (phosphorescent material). By selecting a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting substance, the energy transfer becomes smooth, allowing efficient emission. This structure simultaneously enables high efficiency, low-voltage operation, and a long lifetime of the light-emitting element.

[0217] As a combination of materials that form an exciplex, it is preferable that the HOMO level (highest occupied molecular orbital level) of the hole-transporting material is equal to or higher than the HOMO level of the electron-transporting material. It is also preferable that the LUMO level (lowest unoccupied molecular orbital level) of the hole-transporting material is equal to or higher than the LUMO level of the electron-transporting material. The LUMO level and HOMO level of the material can be derived from the electrochemical properties (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV).

[0218] The formation of exciplexes can be confirmed, for example, by comparing the emission spectra of the hole-transporting material, the electron-transporting material, and the mixed film of these materials and observing the phenomenon that the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak at longer wavelengths). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of the hole-transporting material, the transient PL of the electron-transporting material, and the mixed film of these materials and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lived component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL can also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of the hole-transporting material, the transient EL of the electron-transporting material, and the mixed film of these materials and observing differences in transient response.

[0219] The active layer 183 includes a semiconductor. Examples of the semiconductor include an inorganic semiconductor such as silicon and an organic semiconductor including an organic compound. In this embodiment, an example in which an organic semiconductor is used as the semiconductor included in the active layer is shown. By using an organic semiconductor, the light-emitting layer 193 and the active layer 183 can be formed by the same method (for example, vacuum deposition), which is preferable because a common manufacturing device can be used.

[0220] The active layer 183 is made of an n-type semiconductor material, such as fullerene (e.g., C 60 , C 70Examples of electron-accepting organic semiconductor materials include fullerene derivatives and other fullerenes. Fullerenes have a soccer ball-like shape, which is energetically stable. Fullerenes have deep (low) HOMO and LUMO levels. Because fullerenes have a deep LUMO level, they have extremely high electron-accepting (acceptor) properties. Normally, when the π-electron conjugation (resonance) spreads on a plane, as in benzene, the electron-donating (donor) properties increase, but fullerenes have a spherical shape, so they have high electron-accepting properties despite the large spread of π-electrons. High electron-accepting properties allow charge separation to occur quickly and efficiently, making them useful as light-receiving elements. C 60 , C 70 Both have a wide absorption band in the visible light region, especially C 70 is C 60 It is preferred because it has a larger π-electron conjugated system and a wide absorption band in the long wavelength region compared to the above.

[0221] Furthermore, examples of n-type semiconductor materials include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, metal complexes having a thiazole skeleton, oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, naphthalene derivatives, anthracene derivatives, coumarin derivatives, rhodamine derivatives, triazine derivatives, and quinone derivatives.

[0222] Examples of the p-type semiconductor material of the active layer 183 include electron-donating organic semiconductor materials such as copper(II) phthalocyanine (CuPc), tetraphenyldibenzoperiflanthene (DBP), zinc phthalocyanine (ZnPc), tin phthalocyanine (SnPc), and quinacridone.

[0223] Examples of p-type semiconductor materials include carbazole derivatives, thiophene derivatives, furan derivatives, aromatic amine compounds, etc. Examples of p-type semiconductor materials include naphthalene derivatives, anthracene derivatives, pyrene derivatives, triphenylene derivatives, fluorene derivatives, pyrrole derivatives, benzofuran derivatives, benzothiophene derivatives, indole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, indolocarbazole derivatives, porphyrin derivatives, phthalocyanine derivatives, naphthalocyanine derivatives, quinacridone derivatives, polyphenylenevinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, polythiophene derivatives, etc.

[0224] The HOMO level of the electron-donating organic semiconductor material is preferably shallower (higher) than the HOMO level of the electron-accepting organic semiconductor material, and the LUMO level of the electron-donating organic semiconductor material is preferably shallower (higher) than the LUMO level of the electron-accepting organic semiconductor material.

[0225] It is preferable to use a spherical fullerene as the electron-accepting organic semiconductor material and a planar organic semiconductor material as the electron-donating organic semiconductor material. Molecules with similar shapes tend to aggregate together, and when molecules of the same type aggregate, the energy levels of their molecular orbitals become close, which can improve carrier transport properties.

[0226] For example, the active layer 183 is preferably formed by co-evaporating an n-type semiconductor and a p-type semiconductor.

[0227] The layer 186 that functions as both a light-emitting layer and an active layer is preferably formed using the above-mentioned light-emitting material, n-type semiconductor, and p-type semiconductor.

[0228] The hole injection layer 181, the hole transport layer 182, the active layer 183, the light-emitting layer 193, the electron transport layer 184, the electron injection layer 185, and the layer serving as both the light-emitting layer and the active layer 186 can be made of either a low-molecular-weight compound or a high-molecular-weight compound, and may contain an inorganic compound. Each layer can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), a transfer method, a printing method, an inkjet method, or a coating method.

[0229] Below, a detailed structure of a light-emitting element and a light-emitting element included in a display device of one embodiment of the present invention will be described with reference to FIGS.

[0230] The display device of one embodiment of the present invention may be any of a top emission type that emits light in a direction opposite to a substrate on which a light-emitting element is formed, a bottom emission type that emits light toward a substrate on which a light-emitting element is formed, and a dual emission type that emits light to both sides.

[0231] 17 to 19, a top-emission display device will be described as an example.

[0232] [Configuration example 1] The display device shown in Figures 17A and 17B has, on a substrate 151, a light-emitting element 347B that emits blue (B) light, a light-emitting element 347G that emits green (G) light, and a light-receiving element 347SR that emits red (R) light and has a light-receiving function, via a layer 355 having a transistor.

[0233] 17A shows a case where the light emitting / receiving element 347SR functions as a light emitting element. In FIG. 17A, an example is shown in which the light emitting element 347B emits blue light, the light emitting element 347G emits green light, and the light emitting / receiving element 347SR emits red light.

[0234] Fig. 17B shows a case where the light receiving / emitting element 347SR functions as a light receiving element. Fig. 17B shows an example in which the light receiving / emitting element 347SR detects blue light emitted by the light emitting element 347B and green light emitted by the light emitting element 347G.

[0235] The light emitting element 347B, the light emitting element 347G, and the light emitting / receiving element 347SR each have a pixel electrode 191 and a common electrode 115. In this embodiment, a case will be described as an example in which the pixel electrode 191 functions as an anode and the common electrode 115 functions as a cathode.

[0236] In this embodiment, similarly to the light-emitting element, the light receiving / emitting element 347SR will be described assuming that the pixel electrode 191 functions as an anode and the common electrode 115 functions as a cathode. In other words, the light receiving / emitting element 347SR can detect light incident on the light receiving / emitting element 347SR by applying a reverse bias between the pixel electrode 191 and the common electrode 115 and driving it.

[0237] The common electrode 115 is used in common by the light emitting element 347B, the light emitting element 347G, and the light emitting / receiving element 347SR.

[0238] The materials and thicknesses of the pairs of electrodes of the light-emitting element 347B, the light-emitting element 347G, and the light-emitting / receiving element 347SR can be made the same, which leads to a reduction in manufacturing costs and a simplification of the manufacturing process of the display device.

[0239] The configuration of the display device shown in FIGS. 17A and 17B will be specifically described.

[0240] The light-emitting element 347B has a buffer layer 192B, a light-emitting layer 193B, and a buffer layer 194B in this order over a pixel electrode 191. The light-emitting layer 193B contains a light-emitting material that emits blue light. The light-emitting element 347B has a function of emitting blue light.

[0241] The light-emitting element 347G has a buffer layer 192G, a light-emitting layer 193G, and a buffer layer 194G in this order on a pixel electrode 191. The light-emitting layer 193G contains a light-emitting material that emits green light. The light-emitting element 347G has a function of emitting green light.

[0242] The light emitting / receiving element 347SR has a buffer layer 192R, an active layer 183, a light emitting layer 193R, and a buffer layer 194R, in this order, on the pixel electrode 191. The light emitting layer 193R contains a light emitting material that emits red light. The active layer 183 contains an organic compound that absorbs light of a shorter wavelength than red light (for example, one or both of green light and blue light). Note that the active layer 183 may use an organic compound that absorbs not only visible light but also ultraviolet light. The light emitting / receiving element 347SR has a function of emitting red light. The light emitting / receiving element 347SR has a function of detecting the light emitted by at least one of the light emitting elements 347G and 347B, and preferably has a function of detecting the light emitted by both of them.

[0243] The active layer 183 preferably contains an organic compound that does not easily absorb red light and absorbs light with a shorter wavelength than red light, thereby enabling the light emitting / receiving element 347SR to efficiently emit red light and accurately detect light with a shorter wavelength than red light.

[0244] The pixel electrode 191, the buffer layer 192R, the buffer layer 192G, the buffer layer 192B, the active layer 183, the light-emitting layer 193R, the light-emitting layer 193G, the light-emitting layer 193B, the buffer layer 194R, the buffer layer 194G, the buffer layer 194B, and the common electrode 115 may each have a single-layer structure or a multilayer structure.

[0245] In the display devices shown in FIGS. 17A and 17B, the buffer layer, active layer, and light-emitting layer are layers that are fabricated separately for each device.

[0246] The buffer layers 192R, 192G, and 192B (hereinafter collectively referred to as buffer layers 192) may each have one or both of a hole injection layer and a hole transport layer. Furthermore, the buffer layers 192R, 192G, and 192B may have an electron blocking layer. The buffer layers 194B, 194G, and 194R (hereinafter collectively referred to as buffer layers 194) may each have one or both of an electron injection layer and an electron transport layer. Furthermore, the buffer layers 194R, 194G, and 194B may have a hole blocking layer. Note that for the materials and the like of each layer constituting the light-emitting element, the above-mentioned description of each layer constituting the light-emitting element can be referred to.

[0247] [Configuration example 2] 18A and 18B, the light-emitting element 347B, the light-emitting element 347G, and the light-emitting / receiving element 347SR may have a common layer between a pair of electrodes, which allows the light-emitting / receiving elements to be incorporated into the display device without significantly increasing the number of manufacturing steps.

[0248] The light emitting element 347B, the light emitting element 347G, and the light emitting / receiving element 347SR shown in FIG. 18A have a common layer 112 and a common layer 114 in addition to the configuration shown in FIGS. 17A and 17B.

[0249] The light-emitting element 347B, light-emitting element 347G, and light-receiving element 347SR shown in Figure 18B differ from the configurations shown in Figures 17A and 17B in that they do not have buffer layers 192R, 192G, 192B and buffer layers 194R, 194G, 194B, but have common layers 112 and 114.

[0250] The common layer 112 may have one or both of a hole injection layer and a hole transport layer, and the common layer 114 may have one or both of an electron injection layer and an electron transport layer.

[0251] Each of the common layer 112 and the common layer 114 may have a single layer structure or a laminated structure.

[0252] [Configuration example 3] The display device shown in FIG. 19A is an example in which the laminated structure shown in FIG. 16C is applied to a light emitting / receiving element 347SR.

[0253] The light emitting / receiving element 347SR has, on a pixel electrode 191, a hole injection layer 181, an active layer 183, a hole transport layer 182R, a light emitting layer 193R, an electron transport layer 184, an electron injection layer 185, and a common electrode 115 in this order.

[0254] The hole injection layer 181, the electron transport layer 184, the electron injection layer 185, and the common electrode 115 are layers common to the light emitting element 347G and the light emitting element 347B.

[0255] The light emitting element 347G has a hole injection layer 181, a hole transport layer 182G, a light emitting layer 193G, an electron transport layer 184, an electron injection layer 185, and a common electrode 115 on a pixel electrode 191 in this order.

[0256] The light emitting element 347B has a hole injection layer 181, a hole transport layer 182B, a light emitting layer 193B, an electron transport layer 184, an electron injection layer 185, and a common electrode 115 on a pixel electrode 191 in this order.

[0257] The light-emitting element included in the display device of this embodiment preferably has a microcavity structure. Therefore, one of a pair of electrodes included in the light-emitting element is preferably an electrode that is transparent and reflective to visible light (semi-transmissive / semi-reflective electrode), and the other is preferably an electrode that is reflective to visible light (reflective electrode). When the light-emitting element has a microcavity structure, light emitted from the light-emitting layer can be resonated between the two electrodes, thereby intensifying the light emitted from the light-emitting element.

[0258] The semi-transmitting / semi-reflective electrode can have a laminated structure of a reflective electrode and an electrode that is transparent to visible light (also called a transparent electrode). In this specification, the reflective electrode, which functions as a part of the semi-transmitting / semi-reflective electrode, is sometimes referred to as a pixel electrode or a common electrode, and the transparent electrode is sometimes referred to as an optical adjustment layer, but it can also be said that the transparent electrode (optical adjustment layer) functions as a pixel electrode or a common electrode.

[0259] The light transmittance of the transparent electrode is 40% or more. For example, it is preferable to use an electrode for the light emitting element that has a transmittance of 40% or more for both visible light (light with a wavelength of 400 nm or more and less than 750 nm) and near-infrared light (light with a wavelength of 750 nm or more and 1300 nm or less). The reflectance of the semi-transparent / semi-reflective electrode for both visible light and near-infrared light is 10% or more and 95% or less, preferably 30% or more and 80% or less. The reflectance of the reflective electrode for both visible light and near-infrared light is 40% or more and 100% or less, preferably 70% or more and 100% or less. The resistivity of these electrodes is 1×10 -2 Ωcm or less is preferable.

[0260] The hole transport layers 182B, 182G, and 182R may each function as an optical adjustment layer. Specifically, in the light-emitting element 347B, it is preferable to adjust the film thickness of the hole transport layer 182B so that the optical distance between the pair of electrodes is an optical distance that intensifies blue light. Similarly, in the light-emitting element 347G, it is preferable to adjust the film thickness of the hole transport layer 182G so that the optical distance between the pair of electrodes is an optical distance that intensifies green light. And, in the light-receiving / light-emitting element 347SR, it is preferable to adjust the film thickness of the hole transport layer 182R so that the optical distance between the pair of electrodes is an optical distance that intensifies red light. The layer used as the optical adjustment layer is not limited to the hole transport layer. Note that, when the semi-transmitting / semi-reflective electrode has a stacked structure of a reflective electrode and a transparent electrode, the optical distance between the pair of electrodes refers to the optical distance between the pair of reflective electrodes.

[0261] [Configuration example 4] The display device shown in FIG. 19B is an example in which the laminated structure shown in FIG. 16D is applied to a light emitting / receiving element 347SR.

[0262] The light emitting / receiving element 347SR has, on a pixel electrode 191, a hole injection layer 181, an active layer 183, a light emitting layer 193R, an electron transport layer 184, an electron injection layer 185, and a common electrode 115 in this order.

[0263] The hole injection layer 181, the electron transport layer 184, the electron injection layer 185, and the common electrode 115 are layers common to the light emitting element 347G and the light emitting element 347B.

[0264] The light emitting element 347G has a hole injection layer 181, a hole transport layer 182G, a light emitting layer 193G, an electron transport layer 184, an electron injection layer 185, and a common electrode 115 on a pixel electrode 191 in this order.

[0265] The light emitting element 347B has a hole injection layer 181, a hole transport layer 182B, a light emitting layer 193B, an electron transport layer 184, an electron injection layer 185, and a common electrode 115 on a pixel electrode 191 in this order.

[0266] The hole transport layer is provided in the light-emitting element 347G and the light-emitting element 347B, but not in the light-receiving / light-emitting element 347SR. In this way, in addition to the active layer and the light-emitting layer, there may be a layer that is provided in only one of the light-emitting element and the light-receiving / light-emitting element.

[0267] A detailed configuration of a display device according to one embodiment of the present invention will be described below with reference to FIGS.

[0268] [Display device 310A] 20A and 20B show cross-sectional views of the display device 310A.

[0269] The display device 310A has a light emitting element 190B, a light emitting element 190G, and a light emitting / receiving element 190SR.

[0270] The light emitting element 190B has a pixel electrode 191, a buffer layer 192B, a light emitting layer 193B, a buffer layer 194B, and a common electrode 115. The light emitting element 190B has a function of emitting blue light 321B.

[0271] The light emitting element 190G has a pixel electrode 191, a buffer layer 192G, a light emitting layer 193G, a buffer layer 194G, and a common electrode 115. The light emitting element 190G has a function of emitting green light 321G.

[0272] The light emitting / receiving element 190SR has a pixel electrode 191, a buffer layer 192R, an active layer 183, a light emitting layer 193R, a buffer layer 194R, and a common electrode 115. The light emitting / receiving element 190SR has a function of emitting red light 321R and a function of detecting light 322.

[0273] 20A shows a case where the light emitting / receiving element 190SR functions as a light emitting element. In FIG. 20A, an example is shown in which the light emitting element 190B emits blue light, the light emitting element 190G emits green light, and the light emitting / receiving element 190SR emits red light.

[0274] Fig. 20B shows a case where the light receiving / emitting element 190SR functions as a light receiving element. Fig. 20B shows an example in which the light receiving / emitting element 190SR detects blue light emitted by the light emitting element 190B and green light emitted by the light emitting element 190G.

[0275] The pixel electrode 191 is located on the insulating layer 214. The ends of the pixel electrode 191 are covered with a partition wall 216. Two adjacent pixel electrodes 191 are electrically insulated from each other (also referred to as being electrically separated) by the partition wall 216.

[0276] An organic insulating film is suitable for the partition wall 216. Materials that can be used for the organic insulating film include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins. The partition wall 216 is a layer that transmits visible light. Instead of the partition wall 216, a partition wall that blocks visible light may be provided.

[0277] The display device 310A has a light emitting / receiving element 190SR, a light emitting element 190G, a light emitting element 190B, a transistor 342, and the like between a pair of substrates (substrate 151 and substrate 152).

[0278] The light receiving / emitting element 190SR has a function of detecting light. Specifically, the light receiving / emitting element 190SR is a photoelectric conversion element that receives light 322 incident from outside the display device 310A and converts it into an electrical signal. The light 322 can also be said to be light emitted by one or both of the light receiving / emitting elements 190G and 190B and reflected by an object. The light 322 may also be incident on the light receiving / emitting element 190SR via a lens.

[0279] The light emitting element 190G and the light emitting element 190B have a function of emitting visible light. Specifically, the light emitting element 190G and the light emitting element 190B are electroluminescent elements that emit light toward the substrate 152 by applying a voltage between the pixel electrode 191 and the common electrode 115 (see light 321G and light 321B).

[0280] The buffer layer 192, the light-emitting layer 193, and the buffer layer 194 can also be called organic layers (layers containing an organic compound) or EL layers. The pixel electrode 191 preferably has a function of reflecting visible light. The common electrode 115 has a function of transmitting visible light.

[0281] The pixel electrode 191 is electrically connected to the source or drain of the transistor 342 through an opening provided in the insulating layer 214. The transistor 342 has a function of controlling the driving of a light-emitting element or a light-emitting and receiving element.

[0282] At least a part of the circuit electrically connected to the light emitting / receiving element 190SR is preferably formed using the same material and in the same process as the circuit electrically connected to the light emitting element 190G and the light emitting element 190B, which allows the display device to be thinner and the manufacturing process to be simplified compared to when the two circuits are formed separately.

[0283] The light emitting / receiving element 190SR, the light emitting element 190G, and the light emitting element 190B are preferably covered with a protective layer 195. In FIG. 20A and other figures, the protective layer 195 is provided on and in contact with the common electrode 115. Providing the protective layer 195 prevents impurities from entering the light emitting / receiving element 190SR and the light emitting elements of each color, thereby improving the reliability of the light emitting / receiving element 190SR and the light emitting elements of each color. In addition, the protective layer 195 and the substrate 152 are bonded together by the adhesive layer 142.

[0284] A light-shielding layer BM is provided on the surface of the substrate 152 facing the substrate 151. The light-shielding layer BM has openings at positions overlapping with the light-emitting element 190G and the light-emitting element 190B and at a position overlapping with the light-receiving / light-emitting element 190SR. In this specification and the like, the position overlapping with the light-emitting element 190G or the light-emitting element 190B specifically refers to a position overlapping with the light-emitting region of the light-emitting element 190G or the light-emitting element 190B. Similarly, the position overlapping with the light-receiving / light-emitting element 190SR specifically refers to a position overlapping with the light-emitting region and the light-receiving region of the light-receiving / light-emitting element 190SR.

[0285] As shown in FIG. 20B , the light receiving / emitting element 190SR can detect light emitted by the light emitting element 190G or the light emitting element 190B reflected by an object. However, there are cases where the light emitted by the light emitting element 190G or the light emitting element 190B is reflected within the display device 310A and enters the light receiving / emitting element 190SR without passing through the object. The light-shielding layer BM can suppress the influence of such stray light. For example, if the light-shielding layer BM were not provided, the light 323 emitted by the light emitting element 190G would be reflected by the substrate 152, and reflected light 324 would enter the light receiving / emitting element 190SR. By providing the light-shielding layer BM, it is possible to prevent the reflected light 324 from entering the light receiving / emitting element 190SR. This reduces noise and improves the sensitivity of the sensor using the light receiving / emitting element 190SR.

[0286] The light-shielding layer BM can be made of a material that blocks light emitted from the light-emitting element. The light-shielding layer BM preferably absorbs visible light. For example, the light-shielding layer BM can be made of a black matrix using a metal material or a resin material containing a pigment (such as carbon black) or a dye. The light-shielding layer BM may have a laminated structure of a red color filter, a green color filter, and a blue color filter.

[0287] [Display device 310B] 21A differs from the display device 310A in that the light emitting element 190G, the light emitting element 190B, and the light emitting / receiving element 190SR do not have the buffer layer 192 and the buffer layer 194, but have the common layer 112 and the common layer 114. In the following description of the display device, description of the same configuration as the display device described above may be omitted.

[0288] The layered structure of the light emitting element 190B, the light emitting element 190G, and the light emitting / receiving element 190SR is not limited to the configuration shown in the display devices 310A and 310B. For example, the layered structures shown in Figures 16 to 19 can be applied to each element as appropriate.

[0289] [Display device 310C] Display device 310C in FIG. 21B differs from display device 310B in that it does not have substrate 151 and substrate 152, but has substrate 153, substrate 154, adhesive layer 155, and insulating layer 212.

[0290] The substrate 153 and the insulating layer 212 are bonded together by an adhesive layer 155. The substrate 154 and the protective layer 195 are bonded together by an adhesive layer 142.

[0291] The display device 310C is fabricated by transferring the insulating layer 212, the transistor 342, the light emitting / receiving element 190SR, the light emitting element 190G, and the light emitting element 190B, which are formed on a fabrication substrate, onto the substrate 153. The substrates 153 and 154 are preferably flexible, which can increase the flexibility of the display device 310C. For example, the substrates 153 and 154 are preferably made of resin.

[0292] Substrates 153 and 154 can be made of polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. One or both of substrates 153 and 154 may be made of glass having a thickness sufficient to provide flexibility.

[0293] The substrate of the display device of this embodiment may be a film having high optical isotropy, such as a triacetyl cellulose (TAC, also called cellulose triacetate) film, a cycloolefin polymer (COP) film, a cycloolefin copolymer (COC) film, or an acrylic film.

[0294] Below, a more detailed configuration of a display device according to one embodiment of the present invention will be described with reference to FIGS.

[0295] [Display device 100A] FIG. 22 shows a perspective view of the display device 100A, and FIG. 23 shows a cross-sectional view of the display device 100A.

[0296] The display device 100A has a configuration in which a substrate 152 and a substrate 151 are bonded together. In Fig. 22, the substrate 152 is clearly indicated by a dashed line.

[0297] The display device 100A has a display unit 162, a circuit 164, wiring 165, etc. Fig. 22 shows an example in which an IC (integrated circuit) 173 and an FPC 172 are mounted on the display device 100A. Therefore, the configuration shown in Fig. 22 can also be said to be a display module having the display device 100A, an IC, and an FPC.

[0298] The circuit 164 can be, for example, a scanning line driver circuit.

[0299] The wiring 165 has a function of supplying signals and power to the display unit 162 and the circuit 164. The signals and power are input to the wiring 165 from the outside via the FPC 172 or input to the wiring 165 from the IC 173.

[0300] 22 shows an example in which an IC 173 is provided on a substrate 151 by a COG (Chip On Glass) method or a COF (Chip on Film) method. The IC 173 may be, for example, an IC having a scanning line driving circuit or a signal line driving circuit. The display device 100A and the display module may be configured without an IC. Alternatively, the IC may be mounted on an FPC by a COF method or the like.

[0301] Figure 23 shows an example of a cross section of the display device 100A shown in Figure 22, with a portion of the area including the FPC 172, a portion of the area including the circuit 164, a portion of the area including the display unit 162, and a portion of the area including the end portion cut away.

[0302] The display device 100A shown in FIG. 23 has, between a substrate 151 and a substrate 152, a transistor 201, a transistor 205, a transistor 206, a transistor 207, a light-emitting element 190B, a light-emitting element 190G, a light-emitting element 190SR, and the like.

[0303] The substrate 152 and the insulating layer 214 are bonded via an adhesive layer 142. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light emitting element 190B, the light emitting element 190G, and the light emitting / receiving element 190SR. In FIG. 23, a space 143 surrounded by the substrate 152, the adhesive layer 142, and the insulating layer 214 is filled with an inert gas (nitrogen, argon, etc.), and a hollow sealing structure is applied. The adhesive layer 142 may be provided overlapping the light emitting element 190B, the light emitting element 190G, and the light emitting / receiving element 190SR. Furthermore, the space 143 surrounded by the substrate 152, the adhesive layer 142, and the insulating layer 214 may be filled with a resin different from the adhesive layer 142.

[0304] The light-emitting element 190B has a layered structure in which a pixel electrode 191, a common layer 112, a light-emitting layer 193B, a common layer 114, and a common electrode 115 are layered in this order from the insulating layer 214 side. The pixel electrode 191 is connected to a conductive layer 222b of the transistor 207 through an opening provided in the insulating layer 214. The transistor 207 has a function of controlling driving of the light-emitting element 190B. An end of the pixel electrode 191 is covered with a partition wall 216. The pixel electrode 191 contains a material that reflects visible light, and the common electrode 115 contains a material that transmits visible light.

[0305] The light-emitting element 190G has a layered structure in which a pixel electrode 191, a common layer 112, a light-emitting layer 193G, a common layer 114, and a common electrode 115 are stacked in this order from the insulating layer 214 side. The pixel electrode 191 is connected to a conductive layer 222b of the transistor 206 through an opening provided in the insulating layer 214. The transistor 206 has a function of controlling driving of the light-emitting element 190G.

[0306] The light emitting / receiving element 190SR has a layered structure in which a pixel electrode 191, a common layer 112, an active layer 183, a light emitting layer 193R, a common layer 114, and a common electrode 115 are layered in this order from the insulating layer 214 side. The pixel electrode 191 is electrically connected to a conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214. The transistor 205 has a function of controlling the driving of the light emitting / receiving element 190SR.

[0307] Light emitted by the light emitting element 190B, the light emitting element 190G, and the light receiving / emitting element 190SR is emitted toward the substrate 152. Furthermore, light is incident on the light receiving / emitting element 190SR via the substrate 152 and the space 143. It is preferable that the substrate 152 be made of a material that is highly transparent to visible light.

[0308] The pixel electrode 191 can be manufactured using the same material and the same process. The common layer 112, the common layer 114, and the common electrode 115 are commonly used for the light-emitting element 190B, the light-emitting element 190G, and the light-receiving / light-emitting element 190SR. The light-receiving / light-emitting element 190SR has a configuration in which an active layer 183 is added to the configuration of a light-emitting element that emits red light. Furthermore, the light-emitting element 190B, the light-emitting element 190G, and the light-receiving / light-emitting element 190SR can all have a common configuration except for the configurations of the active layer 183 and the light-emitting layers 193 of each color. This makes it possible to add a light-receiving function to the display unit 162 of the display device 100A without significantly increasing the number of manufacturing processes.

[0309] A light-shielding layer BM is provided on the surface of substrate 152 facing substrate 151. The light-shielding layer BM has openings at positions overlapping with light-emitting element 190B, light-emitting element 190G, and light-receiving / light-emitting element 190SR. By providing the light-shielding layer BM, it is possible to control the range in which light is detected by light-receiving / light-emitting element 190SR. Furthermore, by providing the light-shielding layer BM, it is possible to prevent light from being directly incident on light-receiving / light-emitting element 190SR from light-emitting element 190G or light-emitting element 190B without passing through an object. Therefore, a sensor with low noise and high sensitivity can be realized.

[0310] The transistor 201, the transistor 205, the transistor 206, and the transistor 207 are all formed over a substrate 151. These transistors can be manufactured using the same material and through the same process.

[0311] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 151 in this order. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0312] It is preferable that at least one insulating layer covering the transistor is made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. With this structure, it is possible to effectively prevent impurities from diffusing into the transistor from the outside, thereby improving the reliability of the display device.

[0313] The insulating layer 211, the insulating layer 213, and the insulating layer 215 are preferably formed using an inorganic insulating film. Examples of inorganic insulating films that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, a hafnium oxynitride film, a hafnium nitride oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, a neodymium oxide film, or the like may be used. Two or more of the above insulating films may be stacked. A base film may be provided between the substrate 151 and the transistor. The above inorganic insulating film may also be used for the base film.

[0314] Here, organic insulating films often have lower barrier properties than inorganic insulating films. Therefore, it is preferable that the organic insulating film has an opening near the edge of the display device 100A. This can prevent impurities from entering from the edge of the display device 100A through the organic insulating film. Alternatively, the organic insulating film may be formed so that the edge of the organic insulating film is located inside the edge of the display device 100A, so that the organic insulating film is not exposed at the edge of the display device 100A.

[0315] An organic insulating film is suitable for the insulating layer 214, which functions as a planarizing layer. Materials that can be used for the organic insulating film include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins.

[0316] 23, an opening is formed in the insulating layer 214. This makes it possible to prevent impurities from entering the display unit 162 from the outside through the insulating layer 214, even when an organic insulating film is used for the insulating layer 214. This makes it possible to improve the reliability of the display device 100A.

[0317] The transistor 201, the transistor 205, the transistor 206, and the transistor 207 each include a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as a source and a drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0318] The structure of the transistor included in the display device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0319] The transistors 201, 205, 206, and 207 each have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and supplied with the same signal to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by supplying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0320] The crystallinity of the semiconductor material used for the transistor is not particularly limited, and any of an amorphous semiconductor, a single-crystal semiconductor, and a semiconductor having crystallinity other than single crystal (a microcrystalline semiconductor, a polycrystalline semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a single-crystal semiconductor or a crystalline semiconductor is preferable because it can suppress deterioration of the transistor characteristics.

[0321] The semiconductor layer of the transistor preferably contains a metal oxide (also referred to as an oxide semiconductor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon and single-crystal silicon).

[0322] The semiconductor layer preferably contains, for example, indium, M (wherein M is one or more elements selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more elements selected from aluminum, gallium, yttrium, and tin.

[0323] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) for the semiconductor layer. Alternatively, it is preferable to use an oxide containing indium, gallium, zinc, and tin. Alternatively, it is preferable to use an oxide containing indium and zinc.

[0324] When the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include In:M:Zn=1:1:1 or a composition thereabout, In:M:Zn=1:1:1.2 or a composition thereabout, In:M:Zn=2:1:3 or a composition thereabout, In:M:Zn=3:1:2 or a composition thereabout, In:M:Zn=4:2:3 or a composition thereabout, In:M:Zn=4:2:4.1 or a composition thereabout, In:M:Zn=5:1:3 or a composition thereabout, In:M:Zn=5:1:6 or a composition thereabout, In:M:Zn=5:1:7 or a composition thereabout, In:M:Zn=5:1:8 or a composition thereabout, In:M:Zn=10:1:3 or a composition thereabout, In:M:Zn=6:1:6 or a composition thereabout, and In:M:Zn=5:2:5 or a composition thereabout. The term "nearby composition" includes a range of ±30% of the desired atomic ratio.

[0325] For example, when describing a composition with an atomic ratio of In:Ga:Zn=4:2:3 or thereabout, this includes a case where, when the atomic ratio of In is 4, the atomic ratio of Ga is 1 to 3 and the atomic ratio of Zn is 2 to 4. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=5:1:6 or thereabout, this includes a case where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 5 and less than 7. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=1:1:1 or thereabout, this includes a case where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and less than 2 and the atomic ratio of Zn is greater than 0.1 and less than 2.

[0326] The transistors included in the circuit 164 may have the same structure as or different from the transistors included in the display portion 162. The transistors included in the circuit 164 may all have the same structure or may have two or more types of structures. Similarly, the transistors included in the display portion 162 may all have the same structure or may have two or more types of structures.

[0327] A connection section 204 is provided in an area of ​​the substrate 151 where the substrate 152 does not overlap. In the connection section 204, the wiring 165 is electrically connected to the FPC 172 via a conductive layer 166 and a connection layer 242. The conductive layer 166, which is obtained by processing the same conductive film as the pixel electrode 191, is exposed on the upper surface of the connection section 204. This allows the connection section 204 and the FPC 172 to be electrically connected via the connection layer 242.

[0328] Various optical members can be disposed on the outside of the substrate 152. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light collecting film. In addition, an anti-static film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses scratches caused by use, an impact absorbing layer, etc. may be disposed on the outside of the substrate 152.

[0329] The substrate 151 and the substrate 152 can each be made of glass, quartz, ceramic, sapphire, resin, etc. Using a flexible material for the substrate 151 and the substrate 152 can increase the flexibility of the display device.

[0330] The adhesive layer can be made of various curable adhesives, such as photo-curable adhesives (e.g., ultraviolet curable), reactive curable adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. Materials with low moisture permeability, such as epoxy resin, are particularly preferred. Two-component resins may also be used. Adhesive sheets, etc., may also be used.

[0331] The connection layer may be made of an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0332] Materials that can be used for conductive layers such as the gate, source, and drain of a transistor, as well as various wirings and electrodes that constitute a display device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing these metals as main components, etc. Films containing these materials can be used as a single layer or a stacked layer structure.

[0333] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, may be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) may be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them thin enough to have light-transmitting properties. A stacked film of the above materials may also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These may also be used as conductive layers such as various wirings and electrodes constituting a display device, conductive layers (conductive layers functioning as pixel electrodes, common electrodes, etc.) of light-emitting elements and light-emitting / receiving elements, and the like.

[0334] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0335] [Display device 100B] FIG. 24 shows a cross-sectional view of the display device 100B.

[0336] The display device 100B differs from the display device 100A mainly in that it has a protective layer 195. Detailed descriptions of the same configuration as the display device 100A will be omitted.

[0337] By providing a protective layer 195 that covers the light-emitting element 190B, the light-emitting element 190G, and the light-receiving / light-emitting element 190SR, it is possible to prevent impurities such as water from entering the light-emitting element 190B, the light-emitting element 190G, and the light-receiving / light-emitting element 190SR, thereby improving the reliability of the light-emitting element 190B, the light-emitting element 190G, and the light-receiving / light-emitting element 190SR.

[0338] In a region 228 near the edge of the display device 100B, it is preferable that the insulating layer 215 and the protective layer 195 contact each other through the opening in the insulating layer 214. In particular, it is preferable that the inorganic insulating film of the insulating layer 215 and the inorganic insulating film of the protective layer 195 contact each other. This makes it possible to prevent impurities from entering the display unit 162 from the outside through the organic insulating film. This can therefore improve the reliability of the display device 100B.

[0339] The protective layer 195 may have a single layer or a multilayer structure, and may have, for example, a three-layer structure including an inorganic insulating layer on the common electrode 115, an organic insulating layer on the inorganic insulating layer, and an inorganic insulating layer on the organic insulating layer. In this case, it is preferable that the end of the inorganic insulating layer extends further outward than the end of the organic insulating layer.

[0340] Furthermore, a lens may be provided in the area overlapping with the light emitting / receiving element 190SR, thereby improving the sensitivity and accuracy of the sensor using the light emitting / receiving element 190SR.

[0341] The lens preferably has a refractive index of 1.3 or more and 2.5 or less. The lens can be formed using at least one of an inorganic material and an organic material. For example, a material containing a resin can be used for the lens. Also, a material containing at least one of an oxide and a sulfide can be used for the lens.

[0342] Specifically, resins containing chlorine, bromine, or iodine, resins containing heavy metal atoms, resins containing aromatic rings, resins containing sulfur, etc. can be used for the lenses. Alternatively, materials containing resin and nanoparticles of a material with a higher refractive index than the resin can be used for the lenses. Titanium oxide or zirconium oxide can be used for the nanoparticles.

[0343] In addition, cerium oxide, hafnium oxide, lanthanum oxide, magnesium oxide, niobium oxide, tantalum oxide, titanium oxide, yttrium oxide, zinc oxide, oxides containing indium and tin, or oxides containing indium, gallium, and zinc can be used for the lens. Alternatively, zinc sulfide can be used for the lens.

[0344] In the display device 100B, the protective layer 195 and the substrate 152 are bonded together by an adhesive layer 142. The adhesive layer 142 is provided to overlap the light-emitting element 190B, the light-emitting element 190G, and the light-receiving / light-emitting element 190SR, respectively, and a solid sealing structure is applied to the display device 100B.

[0345] [Display device 100C] FIG. 25A shows a cross-sectional view of the display device 100C.

[0346] The display device 100C differs from the display device 100B in the structure of the transistors.

[0347] The display device 100C includes a transistor 208, a transistor 209, and a transistor 210 over a substrate 151.

[0348] The transistor 208, the transistor 209, and the transistor 210 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a semiconductor layer including a channel formation region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 functioning as a gate insulating layer, a conductive layer 223 functioning as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel formation region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel formation region 231i.

[0349] The conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 225 and the insulating layer 215, respectively. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

[0350] The pixel electrode 191 of the light emitting element 190G is electrically connected to one of a pair of low resistance regions 231n of the transistor 208 via the conductive layer 222b.

[0351] The pixel electrode 191 of the light emitting / receiving element 190SR is electrically connected to the other of the pair of low resistance regions 231n of the transistor 209 via the conductive layer 222b.

[0352] 25A shows an example in which the insulating layer 225 covers the top and side surfaces of the semiconductor layer. On the other hand, in the transistor 202 shown in FIG. 25B, the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231 but does not overlap with the low-resistance region 231n. For example, the structure shown in FIG. 25B can be manufactured by processing the insulating layer 225 using the conductive layer 223 as a mask. In FIG. 25B, the insulating layer 215 is provided to cover the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through openings in the insulating layer 215. Furthermore, an insulating layer 218 may be provided to cover the transistor.

[0353] The display device 100C also differs from the display device 100B in that it does not have the substrate 151 and the substrate 152, but has the substrate 153, the substrate 154, the adhesive layer 155, and the insulating layer 212.

[0354] The substrate 153 and the insulating layer 212 are bonded together by an adhesive layer 155. The substrate 154 and the protective layer 195 are bonded together by an adhesive layer 142.

[0355] The display device 100C is fabricated by transferring the insulating layer 212, the transistor 208, the transistor 209, the transistor 210, the light-emitting element 190SR, the light-emitting element 190G, and the like, which are formed on a fabrication substrate, onto a substrate 153. The substrate 153 and the substrate 154 are preferably flexible, which can increase the flexibility of the display device 100C.

[0356] The insulating layer 212 can be formed using the inorganic insulating film that can be used for the insulating layers 211, 213, and 215.

[0357] As described above, in the display device of this embodiment, a light-receiving / light-emitting element is provided in each sub-pixel that exhibits one of the colors instead of a light-emitting element. The light-receiving / light-emitting element functions as both a light-emitting element and a light-receiving element, so that the pixel can be given a light-receiving function without increasing the number of sub-pixels included in the pixel. Furthermore, the pixel can be given a light-receiving function without reducing the resolution of the display device or the aperture ratio of each sub-pixel.

[0358] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0359] (Embodiment 3) In this embodiment, a metal oxide (also referred to as an oxide semiconductor) that can be used for the OS transistor described in the above embodiment will be described.

[0360] The metal oxide preferably contains at least indium or zinc. It is particularly preferable that it contains indium and zinc. It is also preferable that it contains aluminum, gallium, yttrium, tin, or the like in addition to these. It may also contain one or more elements selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, and the like.

[0361] Furthermore, metal oxides can be formed by sputtering, chemical vapor deposition (CVD) such as metal organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), or the like.

[0362] <Classification of crystal structures> Examples of the crystalline structure of oxide semiconductors include amorphous (including completely amorphous), c-axis-aligned crystalline (CAAC), nanocrystalline (nc), cloud-aligned composite (CAC), single crystal, and polycrystal.

[0363] The crystalline structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectra. For example, it can be evaluated using XRD spectra obtained by GIXD (Grazing-Incidence XRD) measurements. The GIXD method is also called the thin film method or the Seemann-Bohlin method.

[0364] For example, for a quartz glass substrate, the peak shape of the XRD spectrum is nearly symmetrical. On the other hand, for an IGZO film with a crystalline structure, the peak shape of the XRD spectrum is asymmetrical. The asymmetrical peak shape of the XRD spectrum clearly indicates the presence of crystals in the film or substrate. In other words, if the peak shape of the XRD spectrum is not symmetrical, the film or substrate cannot be said to be in an amorphous state.

[0365] The crystalline structure of a film or substrate can also be evaluated by the diffraction pattern (also called the nanobeam electron diffraction pattern) observed using nanobeam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, confirming that the quartz glass is in an amorphous state. Furthermore, a spot-like pattern is observed in the diffraction pattern of an IGZO film deposited at room temperature, rather than a halo. For this reason, it is estimated that an IGZO film deposited at room temperature is neither crystalline nor amorphous, but is in an intermediate state, and it cannot be concluded that it is in an amorphous state.

[0366] <<Oxide semiconductor structure>> Note that oxide semiconductors may be classified differently from the above when focusing on their structures. For example, oxide semiconductors are divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the above-mentioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0367] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0368] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction can be the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region can also be a region with a uniform lattice arrangement. Furthermore, CAAC-OS has a region where multiple crystalline regions are connected in the ab-plane direction, and the region may have distortion. Note that distortion refers to a location where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with a different uniform lattice arrangement in the region where multiple crystalline regions are connected. In other words, CAAC-OS is an oxide semiconductor with a c-axis aligned but no clear orientation in the ab-plane direction.

[0369] Each of the multiple crystalline regions is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of one minute crystal, the maximum diameter of the crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of the crystalline region may be several tens of nm.

[0370] In an In-M-Zn oxide (wherein M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), the CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium (In) and oxygen (hereinafter referred to as an In layer) and a layer containing M, zinc (Zn), and oxygen (hereinafter referred to as an (M, Zn) layer) are stacked. Note that indium and the element M are mutually substituted. Therefore, the (M, Zn) layer may contain indium. The In layer may contain M. The In layer may contain Zn. The layered structure is observed as a lattice image in a high-resolution transmission electron microscope (TEM) image, for example.

[0371] When the CAAC-OS film is subjected to structural analysis using, for example, an XRD apparatus, a peak indicating c-axis orientation is detected at or near 2θ=31° in out-of-plane XRD measurement using θ / 2θ scan. Note that the position of the peak indicating c-axis orientation (2θ value) may vary depending on the type and composition of the metallic elements constituting the CAAC-OS.

[0372] For example, in the electron diffraction pattern of a CAAC-OS film, multiple bright spots are observed, and the spots are observed at positions that are point-symmetric with respect to the spot of the incident electron beam that has passed through the sample (also called the direct spot).

[0373] When the crystalline region is observed from the specific direction, the lattice arrangement within the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the distortion may have a pentagonal, heptagonal, or other lattice arrangement. In the CAAC-OS, no clear grain boundaries are observed even near the distortion. This indicates that the formation of grain boundaries is suppressed by the distortion of the lattice arrangement. This is thought to be because the CAAC-OS can tolerate distortion due to the lack of close-packed arrangement of oxygen atoms in the ab-plane direction and the change in interatomic bond distance caused by metal atom substitution.

[0374] A crystal structure with clear grain boundaries is called polycrystalline. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in the on-state current and field-effect mobility of a transistor. Therefore, CAAC-OS, which lacks clear grain boundaries, is one of the crystalline oxides with a crystal structure suitable for use in the semiconductor layer of a transistor. Zn is preferred for use in CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are suitable because they can suppress the generation of grain boundaries more effectively than In oxide.

[0375] CAAC-OS is an oxide semiconductor with high crystallinity and no clear grain boundaries. Therefore, it can be said that the CAAC-OS is less susceptible to a decrease in electron mobility due to grain boundaries. Furthermore, since the crystallinity of an oxide semiconductor can be reduced by impurities or defects, the CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, oxide semiconductors with CAAC-OS have stable physical properties. Therefore, oxide semiconductors with CAAC-OS are heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even under high temperatures (so-called thermal budget) during the manufacturing process. Therefore, using a CAAC-OS for an OS transistor can increase the flexibility of the manufacturing process.

[0376] [nc-OS] The nc-OS has periodic atomic arrangement in a microscopic region (e.g., a region of 1 nm to 10 nm, particularly a region of 1 nm to 3 nm). In other words, the nc-OS has microcrystalline structures. The size of the microcrystalline structures is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore these microcrystalline structures are also called nanocrystalline structures. Furthermore, the nc-OS exhibits no regularity in the crystal orientation between different nanocrystalline structures. Therefore, the entire film lacks orientation. Therefore, depending on the analytical method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor. For example, when a structural analysis of an nc-OS film is performed using an XRD apparatus, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Furthermore, when an nc-OS film is subjected to electron diffraction (also known as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of nanocrystalline structures (e.g., 50 nm or larger), a halo-like diffraction pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystals (for example, 1 nm to 30 nm), an electron diffraction pattern can be obtained in which multiple spots are observed within a ring-shaped region centered on the direct spot.

[0377] [a-like OS] The a-like OS is an oxide semiconductor having a structure between the nc-OS and the amorphous oxide semiconductor. The a-like OS has a pore or low-density region. That is, the a-like OS has lower crystallinity than the nc-OS and CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and CAAC-OS.

[0378] <<Oxide semiconductor structure>> Next, the above-mentioned CAC-OS will be described in detail, which relates to the material composition.

[0379] [CAC-OS] CAC-OS is a material structure in which elements constituting a metal oxide are unevenly distributed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range. Hereinafter, a metal oxide in which one or more metal elements are unevenly distributed and the regions containing the metal elements are mixed in a size range of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or a similar size range, is also referred to as a mosaic or patch state.

[0380] Furthermore, CAC-OS has a mosaic structure in which the material is separated into first and second regions, and the first regions are distributed throughout the film (hereinafter also referred to as a cloud structure). That is, CAC-OS is a composite metal oxide having a structure in which the first and second regions are mixed.

[0381] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in the In-Ga-Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS in the In-Ga-Zn oxide, the first region is a region where [In] is larger than [In] in the composition of the CAC-OS film. The second region is a region where [Ga] is larger than [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is a region where [In] is larger than [In] in the second region and [Ga] is smaller than [Ga] in the second region. The second region is a region where [Ga] is larger than [Ga] in the first region and [In] is smaller than [In] in the first region.

[0382] Specifically, the first region is a region whose main component is indium oxide, indium zinc oxide, or the like. The second region is a region whose main component is gallium oxide, gallium zinc oxide, or the like. In other words, the first region can be rephrased as a region whose main component is In. The second region can be rephrased as a region whose main component is Ga.

[0383] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0384] In addition, CAC-OS in In-Ga-Zn oxide refers to a material structure containing In, Ga, Zn, and O, in which some regions primarily composed of Ga and other regions primarily composed of In are randomly arranged in a mosaic pattern. Therefore, it is presumed that CAC-OS has a structure in which metal elements are distributed nonuniformly.

[0385] The CAC-OS can be formed, for example, by a sputtering method under conditions where the substrate is not intentionally heated. When the CAC-OS is formed by a sputtering method, any one or more of an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. The lower the flow rate ratio of oxygen gas to the total flow rate of deposition gas during deposition, the better. For example, the flow rate ratio of oxygen gas to the total flow rate of deposition gas during deposition is preferably 0% or more and less than 30%, and more preferably 0% or more and 10% or less.

[0386] Furthermore, for example, in the case of CAC-OS in an In-Ga-Zn oxide, EDX mapping obtained using EDX (Energy Dispersive X-ray spectroscopy) confirms that the CAC-OS has a structure in which a region containing In as a main component (first region) and a region containing Ga as a main component (second region) are unevenly distributed and mixed.

[0387] Here, the first region has higher conductivity than the second region. That is, the flow of carriers through the first region causes the metal oxide to exhibit conductivity. Therefore, the first region is distributed in a cloud-like manner in the metal oxide, thereby achieving a high field-effect mobility (μ).

[0388] On the other hand, the second region has higher insulating properties than the first region. That is, the second region is distributed in the metal oxide, thereby suppressing leakage current.

[0389] Therefore, when CAC-OS is used in a transistor, the conductivity due to the first region and the insulating property due to the second region act complementarily, thereby providing the CAC-OS with a switching function (the ability to turn on / off). In other words, CAC-OS has a conductive function in part of the material and an insulating function in part of the material, and the material as a whole functions as a semiconductor. By separating the conductive function from the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0390] Furthermore, a transistor using CAC-OS has high reliability, making it ideal for various semiconductor devices such as display devices.

[0391] Oxide semiconductors have a variety of structures, each with different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

[0392] <Transistors containing oxide semiconductors> Next, a case where the oxide semiconductor is used in a transistor will be described.

[0393] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0394] For the transistor, an oxide semiconductor with a low carrier concentration is preferably used. For example, the carrier concentration of the oxide semiconductor is 1×10 17 cm -3 Less than 1 × 10 15 cm -3 or less, more preferably 1 × 10 13 cm -3Less than 1×10, more preferably 11 cm -3 or less, more preferably 1 × 10 10 cm -3 Less than 1 x 10 -9 cm -3 That is all. Note that in order to reduce the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film may be reduced to reduce the density of defect states. In this specification and the like, a semiconductor having a low impurity concentration and a low density of defect states is referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor. Note that an oxide semiconductor having a low carrier concentration may also be referred to as a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor.

[0395] Furthermore, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states, and therefore the density of trap states may also be low.

[0396] Furthermore, charges trapped in the trap states of an oxide semiconductor take a long time to disappear and may behave like fixed charges. Therefore, a transistor in which a channel formation region is formed in an oxide semiconductor with a high density of trap states may have unstable electrical characteristics.

[0397] Therefore, in order to stabilize the electrical characteristics of a transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in the adjacent film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0398] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0399] When an oxide semiconductor contains silicon or carbon, which is one of the Group 14 elements, defect levels are formed in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon near the interface with the oxide semiconductor (concentration obtained by secondary ion mass spectrometry (SIMS)) are calculated to be 2×10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0400] Furthermore, when an oxide semiconductor contains an alkali metal or alkaline earth metal, defect levels may be formed and carriers may be generated. Therefore, a transistor using an oxide semiconductor containing an alkali metal or alkaline earth metal is likely to have normally-on characteristics. Therefore, when the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 18 atoms / cm 3 Less than or equal to 2 x 10 16 atoms / cm 3 Do the following:

[0401] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Alternatively, when nitrogen is contained in an oxide semiconductor, trap states may be formed. As a result, the electrical characteristics of the transistor may become unstable. For this reason, the nitrogen concentration in the oxide semiconductor obtained by SIMS is set to 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than 1×10, more preferably 18 atoms / cm 3 Less than 5 × 10, more preferably 17 atoms / cm 3 Do the following:

[0402] Furthermore, hydrogen contained in an oxide semiconductor may react with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. When hydrogen enters the oxygen vacancy, electrons serving as carriers may be generated. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons serving as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. For this reason, it is preferable to reduce the amount of hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in an oxide semiconductor measured by SIMS is 1×10 20 atoms / cm 3 Less than 1 x 10 19 atoms / cm 3 less than 5 × 10 18 atoms / cm 3 less than 1×10 18 atoms / cm 3 Make it less than.

[0403] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0404] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0405] (Fourth embodiment) In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS.

[0406] The electronic devices of this embodiment include the display device of one embodiment of the present invention. For example, the display device of one embodiment of the present invention can be applied to a display portion of an electronic device. The display device of one embodiment of the present invention has a function of detecting light, and therefore, can perform biometric authentication on the display portion, detect a touch operation (contact or approach), and the like. This can improve the functionality, convenience, and the like of the electronic device.

[0407] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound playback devices.

[0408] The electronic device of this embodiment may have a sensor (including a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0409] The electronic device of the present embodiment can have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to execute various software (programs), a wireless communication function, a function to read out programs or data recorded on a recording medium, etc.

[0410] Electronic device 6500 shown in FIG. 26A is a portable information terminal that can be used as a smartphone.

[0411] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508. The display portion 6502 has a touch panel function.

[0412] The display device of one embodiment of the present invention can be applied to the display portion 6502.

[0413] FIG. 26B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0414] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0415] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0416] In an area outside the display unit 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0417] The flexible display of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. Furthermore, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0418] When the display device of one embodiment of the present invention is used for the display panel 6511, an image can be captured in the display portion 6502. For example, a fingerprint can be captured on the display panel 6511 and fingerprint authentication can be performed.

[0419] The display portion 6502 further includes a touch sensor panel 6513, which allows the display portion 6502 to have a touch panel function. The touch sensor panel 6513 can be of any of various types, such as a capacitive type, a resistive type, a surface acoustic wave type, an infrared type, an optical type, or a pressure-sensitive type. Alternatively, the display panel 6511 may function as a touch sensor, in which case the touch sensor panel 6513 is not necessarily provided.

[0420] 27A shows an example of a television device. A television device 7100 has a display unit 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0421] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0422] 27A can be operated using an operation switch provided on the housing 7101, a separate remote control 7111, or the like. Alternatively, a touch sensor may be provided in the display unit 7000, and the television unit 7100 may be operated by touching the display unit 7000 with a finger or the like. The remote control 7111 may have a display unit that displays information output from the remote control 7111. The channel and volume can be controlled using the operation keys or touch panel provided on the remote control 7111, and the video displayed on the display unit 7000 can be controlled.

[0423] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. In addition, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0424] 27B shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214. The housing 7211 includes a display portion 7000.

[0425] The display device of one embodiment of the present invention can be applied to the display portion 7000.

[0426] 27C and 27D show an example of digital signage.

[0427] 27C includes a housing 7301, a display unit 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0428] 27D shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0429] 27C and 27D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0430] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it will attract people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[0431] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000 but also allows the user to intuitively operate it. Furthermore, when used to provide information such as route information or traffic information, intuitive operation can improve usability.

[0432] 27C and 27D, it is preferable that digital signage 7300 or digital signage 7400 can wirelessly link with information terminal 7311 or information terminal 7411, such as a smartphone carried by a user. For example, advertising information displayed on display unit 7000 can be displayed on the screen of information terminal 7311 or information terminal 7411. Furthermore, by operating information terminal 7311 or information terminal 7411, the display on display unit 7000 can be switched.

[0433] Furthermore, it is also possible to run a game on the digital signage 7300 or the digital signage 7400 using the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller), thereby allowing an unspecified number of users to simultaneously participate in and enjoy the game.

[0434] The electronic device shown in Figures 28A to 28F has a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including the function of measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays), a microphone 9008, etc.

[0435] The electronic devices shown in Figures 28A to 28F have various functions. For example, they may have a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, or time, etc., a function to control processing using various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. Note that the functions of the electronic devices are not limited to these, and they may have various other functions. The electronic devices may have multiple display units. Furthermore, the electronic devices may have a function to include a camera or the like to capture still images, videos, etc. and store them on a recording medium (external or built-in to the camera), a function to display the captured images on the display unit, etc.

[0436] The electronic devices shown in FIGS. 28A to 28F will be described in detail below.

[0437] FIG. 28A is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 can be used as, for example, a smartphone. The mobile information terminal 9101 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, and the like. The mobile information terminal 9101 can display text, image information, and the like on multiple surfaces thereof. FIG. 28A shows an example in which three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notifications of incoming emails, SNS messages, phone calls, etc., the title of the email or SNS message, the sender's name, the date and time, the remaining battery level, and the strength of antenna reception. Alternatively, the icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0438] 28B is a perspective view showing mobile information terminal 9102. Mobile information terminal 9102 has a function of displaying information on three or more sides of display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different sides. For example, while carrying mobile information terminal 9102 in a breast pocket of clothes, the user can check information 9053 displayed in a position that can be observed from above mobile information terminal 9102. The user can check the display without taking mobile information terminal 9102 out of their pocket and decide, for example, whether to answer a call.

[0439] 28C is a perspective view showing a wristwatch-type mobile information terminal 9200. The display surface of the display unit 9001 is curved, and a display can be displayed along the curved display surface. The mobile information terminal 9200 can also perform hands-free conversations by communicating with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and charging with other information terminals via a connection terminal 9006. Charging may be performed by wireless power supply.

[0440] 28D to 28F are perspective views showing a foldable mobile information terminal 9201. FIG. 28D is a perspective view of the mobile information terminal 9201 in an unfolded state, FIG. 28F is a perspective view of the mobile information terminal 9201 in a folded state, and FIG. 28E is a perspective view of a state in the process of changing from one of FIG. 28D and FIG. 28F to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent viewability of the display. The display unit 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display unit 9001 can be bent with a curvature radius of 0.1 mm or more and 150 mm or less.

[0441] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification. [Explanation of symbols]

[0442] Tr1: Transistor: SW1: Switch: SW2: Switch: SW3: Switch: SW4: Switch: SA: Light-emitting / receiving element: CS: Capacitor: AL: Wiring: CL: Wiring: WX: Wiring: SL: Wiring: V data :Data potential:V gp :Potential:V gs :Voltage:V off :Potential:V RS :Potential:V sig : Potential: SL1: Wiring: SL2: Wiring: SL3: Wiring: GL: Wiring: SE: Wiring: AEN: Wiring: REN: Wiring: SR: Light emitting / receiving element: ELB: Light emitting element: ELG: Light emitting element: M1: Transistor: M2: Transistor: M3: Transistor: M4: Transistor: M5: Transistor: M6: Transistor: 10: Display device: 11: Display unit: 12: Drive circuit unit: 13: Drive circuit unit: 14: Drive circuit unit: 15: Circuit unit: 20R: Pixel: 20B: Pixel: 20G: Pixel: 21R: Circuit: 21B: Circuit: 21G: Circuit: 30: Pixel: 30A: Pixel: 30B: Pixel: 30G: Pixel

Claims

1. a first transistor, a first element, and first to third wirings; the first element has an anode and a cathode; one of the anode and the cathode of the first element is electrically connected to the first wiring; the other of the anode and the cathode of the first element is electrically connected to one of the source and the drain of the first transistor via the first switch; the other of the source and the drain of the first transistor is electrically connected to the second wiring via the second switch; a gate of the first transistor is electrically connected to the third wiring via the third switch; the first element has a function of emitting light of a first color and a function of receiving light of a second color and converting the received light into an electrical signal; Display device.

2. In claim 1, It has a capacitance element, one electrode of the capacitance element is electrically connected to the gate of the first transistor; the other electrode of the capacitance element is electrically connected to one of the source and the drain of the first transistor; Display device.

3. In claim 1 or claim 2, the second wiring has a function of reading out a first current flowing through the first transistor, the first current is a current corresponding to the electrical signal; Display device.

4. In any one of claims 1 to 3, the first wiring is electrically connected to the cathode of the first element; one of a source and a drain of the first transistor is electrically connected to an anode of the first element via the first switch; the second wiring has a function of supplying a potential lower than a potential of the first wiring to an anode of the first element via the second switch, the first transistor, and the first switch; Display device.

5. a first transistor, a first element, and first to fourth wirings; the first element has an anode and a cathode; one of the anode and the cathode of the first element is electrically connected to the first wiring; the other of the anode and the cathode of the first element is electrically connected to one of the source and the drain of the first transistor via the first switch; the other of the source and the drain of the first transistor is electrically connected to the second wiring via the second switch; a gate of the first transistor is electrically connected to the third wiring via the third switch; one of the source and the drain of the first transistor is electrically connected to the fourth wiring via the fourth switch; the first element has a function of emitting light of a first color and a function of receiving light of a second color and converting the received light into an electrical signal; Display device.

6. In claim 5, It has a capacitance element, one electrode of the capacitance element is electrically connected to the gate of the first transistor; the other electrode of the capacitance element is electrically connected to one of the source and the drain of the first transistor; Display device.

7. In claim 5 or claim 6, the fourth wiring has a function of reading out a first current flowing through the first transistor, the first current is a current corresponding to the electrical signal; Display device.

8. In any one of claims 5 to 7, the first wiring is electrically connected to the cathode of the first element; one of a source and a drain of the first transistor is electrically connected to an anode of the first element via the first switch; the fourth wiring has a function of supplying a potential lower than a potential of the first wiring to the anode of the first element via the fourth switch and the first switch; Display device.

9. In any one of claims 1 to 8, the wavelength of the second color light is shorter than the wavelength of the first color light; Display device.

10. In any one of claims 1 to 9, The first element has a light-emitting layer and an active layer. Display device.

11. In claim 10, The active layer comprises an electron-accepting material and an electron-donating material. Display device.

12. In claim 10, the active layer comprises fullerene or a fullerene derivative and copper (II) phthalocyanine, tetraphenyldibenzoperiflanthene, zinc phthalocyanine, tin phthalocyanine, or quinacridone; Display device.

13. In any one of claims 1 to 9, an insulating layer having a region located above a gate electrode of the first transistor; a first electrode having a region in contact with the upper surface of the insulating layer; a second electrode having a region located above the first electrode; the first electrode functions as the other of the anode and the cathode of the first element; the second electrode functions as one of an anode and a cathode of the first element; Display device.

14. In claim 13, a light-emitting layer located between the first electrode and the second electrode; an active layer located between the light-emitting layer and the first electrode or between the light-emitting layer and the second electrode; Display device.

15. In claim 14, The active layer comprises an electron-accepting material and an electron-donating material. Display device.

16. In claim 14, the active layer comprises fullerene or a fullerene derivative and copper (II) phthalocyanine, tetraphenyldibenzoperiflanthene, zinc phthalocyanine, tin phthalocyanine, or quinacridone; Display device.

17. In any one of claims 1 to 16, a second element; the second element has an anode and a cathode; one of the anode and the cathode of the second element is electrically connected to the first wiring; the second element has a function of emitting light of the second color; Display device.

18. In claim 17, a fifth switch, a second transistor, and fifth and sixth wirings; the other of the anode and the cathode of the second element is electrically connected to one of the source and the drain of the second transistor; the other of the source and the drain of the second transistor is electrically connected to the fifth wiring; a gate of the second transistor is electrically connected to the sixth wiring via the fifth switch; Display device.

Images