Light emitting apparatus and electronic equipment

Abstract

Provided is a light emitting device that is produced by a photolithography method and has high definition and good characteristics. Provided is a light emitting apparatus in which in adjacent first light emitting device and second light emitting device, the first light emitting device has a first EL layer, the second light emitting device has a second EL layer, the first EL layer has at least a first light emitting layer and a first electron transport layer, the second EL layer has at least a second light emitting layer and a second electron transport layer, the first electron transport layer includes a first heteroaromatic compound and a first organic compound, the second electron transport layer includes a second heteroaromatic compound and a second organic compound, the ends of the first light emitting layer and the first electron transport layer match each other, the ends of the second light emitting layer and the second electron transport layer substantially match each other, and the distance between the first light emitting device and the second light emitting device facing each other is 2-5 μm.

Description

Light-emitting device and electronic device

[0001] One embodiment of the present invention relates to an organic compound, a light-emitting element, a light-emitting device, a display module, a lighting module, a display device, a light-emitting device, an electronic device, a lighting device, and an electronic device. Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Therefore, more specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, an imaging device, a driving method thereof, or a manufacturing method thereof.

[0002] Light-emitting devices (organic EL devices) that utilize electroluminescence (EL) using organic compounds are becoming increasingly practical. The basic structure of these light-emitting devices is a pair of electrodes sandwiching an organic compound layer (EL layer) containing a light-emitting material. By applying a voltage to this device, carriers are injected, and the recombination energy of the carriers is utilized to emit light from the light-emitting material.

[0003] Since such light-emitting devices are self-luminous, when used as display pixels, they offer advantages such as higher visibility and no need for backlighting compared to liquid crystal displays, making them particularly suitable for flat panel displays. Another major advantage of displays using such light-emitting devices is that they can be fabricated to be thin and lightweight. Another feature is their extremely fast response time.

[0004] Furthermore, these light-emitting devices can have a continuous light-emitting layer formed two-dimensionally, enabling them to emit light in a planar form. This is a feature that is difficult to obtain with point light sources such as incandescent lamps and LEDs, or linear light sources such as fluorescent lamps, making them highly useful as planar light sources for lighting applications.

[0005] Although light emitting devices using such light emitting devices are suitable for a variety of electronic devices, research and development is ongoing to find light emitting devices with even better characteristics.

[0006] In order to obtain a light-emitting device with higher resolution using an organic EL device, research has been conducted into patterning organic layers using photolithography methods using photoresist, etc., instead of deposition methods using metal masks. By using photolithography, a light-emitting device with high resolution, where the spacing between EL layers is several micrometers, can be obtained (see, for example, Patent Document 1).

[0007] Special table 2018-521459 publication

[0008] In photolithography patterning, heat may be applied during the fabrication of a photomask. The materials used in the organic layers of light-emitting devices, particularly in the electron transport region, can crystallize at low temperatures due to their layered structure. This can lead to problems such as crystallization of the organic layers due to the heat applied during photomask fabrication. While methods such as reducing the heat applied during photomask hardening are sometimes employed, etching using an insufficiently hardened photomask limits the degree of fineness that can be achieved, resulting in the problem of not being able to achieve the desired fineness.

[0009] In view of the above, an object of one embodiment of the present invention is to provide a light-emitting device manufactured by a photolithography method, which has higher definition and favorable characteristics.

[0010] Therefore, one embodiment of the present invention provides a light-emitting device formed by a photolithography method, in which an electron transport layer of a light-emitting device is formed of at least two organic compounds.

[0011] That is, one aspect of the present invention provides a semiconductor device having a first light-emitting device and a second light-emitting device adjacent to each other on an insulating plane, the first light-emitting device having a first anode, a first cathode, and a first EL layer sandwiched between the first anode and the first cathode, the second light-emitting device having a second anode, a second cathode, and a second EL layer sandwiched between the second anode and the second cathode, the first EL layer having at least a first light-emitting layer and a first electron transport layer, and the first electron transport layer being located between the first light-emitting layer and the first cathode, the second EL layer having at least a second light-emitting layer and a second electron transport layer, and the second electron transport layer being located between the second light-emitting layer and the second cathode, the first electron transport layer comprises a first heteroaromatic compound having at least a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound; the second electron transport layer comprises a second heteroaromatic compound having at least a second heteroaromatic ring and a second organic compound different from the second heteroaromatic compound; an end of the first light-emitting layer and an end of the first electron transport layer substantially coincide with each other at a first end when viewed from a direction perpendicular to the insulating plane; an end of the second light-emitting layer and an end of the second electron transport layer substantially coincide with each other at a second end when viewed from a direction perpendicular to the insulating plane; and a distance between the opposing first end and second end is 2 μm to 5 μm.

[0012] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron-transporting layer is composed of a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, and the second electron-transporting layer is composed of a second heteroaromatic compound having a second heteroaromatic ring and a second organic compound different from the second heteroaromatic compound.

[0013] Alternatively, another aspect of the present invention provides a light-emitting device having a first light-emitting device and a second light-emitting device adjacent to each other on an insulating plane, the first light-emitting device having a first anode, a first cathode, and a first EL layer sandwiched between the first anode and the first cathode, the second light-emitting device having a second anode, a second cathode, and a second EL layer sandwiched between the second anode and the second cathode, the first EL layer having, from the first anode side, at least a light-emitting layer 1a, a first charge-generating layer, a light-emitting layer 1b, and an electron-transporting layer 1b in this order, the electron-transporting layer 1b being located between the light-emitting layer 1b and the first cathode, the second EL layer having, from the second anode side, at least a light-emitting layer 2a, a second charge-generating layer, a light-emitting layer 2b, and an electron-transporting layer 2b in this order, a second heteroaromatic compound having at least a first heteroaromatic ring and a second organic compound different from the second heteroaromatic compound; an end of the light-emitting layer 1a and an end of the electron transport layer 1b substantially coincide with each other at a first end when viewed from a direction perpendicular to the insulating plane; an end of the light-emitting layer 2a and an end of the electron transport layer 2b substantially coincide with each other at a second end when viewed from a direction perpendicular to the insulating plane; and a distance between the opposing first end and second end is 2 μm to 5 μm.

[0014] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described structure, wherein the electron transport layer 1 b is composed of a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, and the electron transport layer 2 b is composed of a second heteroaromatic compound having a second heteroaromatic ring and a second organic compound different from the second heteroaromatic compound.

[0015] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first heteroaromatic ring and the second heteroaromatic ring are the same.

[0016] Another embodiment of the present invention is a light-emitting device having the above structure, in which the first heteroaromatic compound and the second heteroaromatic compound are the same.

[0017] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first organic compound and the second organic compound are the same.

[0018] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first organic compound includes a heteroaromatic ring.

[0019] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the first organic compound includes the same heteroaromatic ring as the first heteroaromatic ring.

[0020] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the second organic compound is an organic compound including a heteroaromatic ring.

[0021] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the second organic compound includes the same heteroaromatic ring as the second heteroaromatic ring.

[0022] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described structure, wherein the first heteroaromatic compound and the first organic compound are each contained in the first electron transport layer at a content of 10% by weight or more, and the second heteroaromatic compound and the second organic compound are each contained in the second electron transport layer at a content of 10% by weight or more.

[0023] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described structure, wherein the first heteroaromatic compound and the first organic compound are each contained in the electron transport layer 1b at a content of 10% by weight or more, and the second heteroaromatic compound and the second organic compound are each contained in the electron transport layer 2b at a content of 10% by weight or more.

[0024] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the first organic compound and / or the second organic compound is a heteroaromatic compound containing two or more nitrogen atoms.

[0025] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first organic compound and / or the second organic compound has a heteroaromatic ring containing two or more nitrogen atoms.

[0026] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first heteroaromatic compound and / or the second heteroaromatic compound contains two or more nitrogen atoms.

[0027] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the first electron-transport layer and the second electron-transport layer, or the electron-transport layer 1b and the electron-transport layer 2b, do not contain a metal complex.

[0028] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron transport layer and the second electron transport layer, or the electron transport layer 1 b and the electron transport layer 2 b, do not contain an alkali metal complex or an alkaline earth metal complex.

[0029] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first electron-transporting layer and the second electron-transporting layer do not contain an alkali metal quinolinolate or an alkaline earth metal quinolinolate.

[0030] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the first heteroaromatic ring and / or the second heteroaromatic ring contains two or more nitrogen atoms.

[0031] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the electron transport layer 1b and the electron transport layer 2b do not contain lithium.

[0032] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the first heteroaromatic ring and / or the second heteroaromatic ring is a π-electron-deficient heteroaromatic ring.

[0033] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first heteroaromatic ring and / or the second heteroaromatic ring is a fused heteroaromatic ring.

[0034] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first heteroaromatic compound and / or the second heteroaromatic compound is an organic compound having a π-electron-deficient heteroaromatic ring.

[0035] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first heteroaromatic ring and / or the second heteroaromatic ring is any one of a heteroaromatic ring having a polyazole skeleton, a heteroaromatic ring having a pyridine skeleton, a heteroaromatic ring having a diazine skeleton, and a heteroaromatic ring having a triazine skeleton.

[0036] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described structure, wherein the first EL layer has an electron transport layer 1a between the light-emitting layer 1a and the first intermediate layer, the second EL layer has an electron transport layer 2a between the light-emitting layer 2a and the second intermediate layer, and the first a electron transport layer and the second a electron transport layer have structures different from the electron transport layer 1b and the electron transport layer 2b, respectively.

[0037] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described structure, wherein the first EL layer has an electron transport layer 1a between the light-emitting layer 1a and the first intermediate layer, and the second EL layer has an electron transport layer 2a between the light-emitting layer 2a and the second intermediate layer, and the electron transport layer 1a and the electron transport layer 2a have structures similar to those of the electron transport layer 1b and the electron transport layer 2b, respectively.

[0038] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first a electron-transporting layer and / or the second a electron-transporting layer is formed using one type of organic compound.

[0039] Another embodiment of the present invention is a light-emitting device having the above structure, in which the first intermediate layer and the second intermediate layer are charge generation layers.

[0040] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described structure, wherein the first EL layer has a first electron injection layer between the first electron transport layer and the first cathode and in contact with the first cathode; the second EL layer has a second electron injection layer between the second electron transport layer and the second cathode and in contact with the second cathode; and the first electron injection layer and the second electron injection layer are continuous in the first light-emitting device and the second light-emitting device.

[0041] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first cathode and the second cathode are continuous with each other in the first light-emitting device and the second light-emitting device.

[0042] Another embodiment of the present invention is an electronic device including any one of the above light-emitting devices, a sensor, an operation button, and a speaker or a microphone.

[0043] In this specification, the term "light-emitting device" includes an image display device using a light-emitting device. The term "light-emitting device" may also include a module in which a connector, such as an anisotropic conductive film or a TCP (Tape Carrier Package), is attached to a light-emitting device, a module in which a printed wiring board is provided at the end of a TCP, or a module in which an IC (integrated circuit) is directly mounted on a light-emitting device using a COG (Chip On Glass) method. Furthermore, lighting fixtures and the like may have a light-emitting device.

[0044] Therefore, according to one embodiment of the present invention, a light-emitting device manufactured by a photolithography method can be provided that has higher definition and favorable characteristics.

[0045] Note that the description of this effect does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc.

[0046] FIGS. 1A to 1D are diagrams illustrating a light-emitting device. FIGS. 2A to 2H are diagrams illustrating a method for manufacturing a light-emitting device. FIGS. 3A to 3G are diagrams illustrating a method for manufacturing a light-emitting device. FIGS. 4A to 4H are diagrams illustrating a method for manufacturing a light-emitting device. FIGS. 5A to 5D are diagrams illustrating a configuration example of a display device. FIGS. 6A to 6F are diagrams illustrating a method for manufacturing a display device. FIGS. 7A to 7F are diagrams illustrating an example of a method for manufacturing a display device. FIG. 8 is a perspective view illustrating an example of a display device. FIGS. 9A and 9B are cross-sectional views illustrating an example of a display device. FIG. 10A is a cross-sectional view illustrating an example of a display device. FIG. 10B is a cross-sectional view illustrating an example of a transistor. FIGS. 11A and 11B are perspective views illustrating an example of a display module. FIG. 12 is a cross-sectional view illustrating an example of a display device. FIG. 13 is a cross-sectional view illustrating an example of a display device. FIG. 14 is a cross-sectional view illustrating an example of a display device. FIGS. 15A and 15B are diagrams illustrating a configuration example of a display device. FIGS. 16A and 16B are diagrams illustrating examples of electronic devices. FIGS. 17A to 17D are diagrams illustrating examples of electronic devices. FIGS. 18A to 18F are diagrams illustrating an example of an electronic device. FIGS. 19A to 19F are diagrams illustrating an example of an electronic device. FIG. 20 is a photograph according to an example. FIG. 21 is a photograph according to an example. FIG. 22 is a diagram illustrating the configuration of a light-emitting device according to an example. FIG. 23 shows the luminance-current density characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 24 shows the current efficiency-luminance characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 25 shows the luminance-voltage characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 26 shows the current-voltage characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 27 shows the external quantum efficiency-luminance characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 28 shows the emission spectra of light-emitting device 1 and comparative light-emitting device 1. FIG. 29 shows the reliability of light-emitting device 1 and comparative light-emitting device 1. FIGS. 30A to 30D are diagrams illustrating light-emitting devices. FIGS. 31A to 31H are diagrams illustrating a method for fabricating light-emitting devices. FIGS. 32A to 32G are diagrams illustrating a method for fabricating light-emitting devices. 33A to 33H are diagrams illustrating a method for fabricating a light-emitting device.34A and 34B are diagrams illustrating a light emitting device.

[0047] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0048] In this specification, etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. In addition, in this specification, etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0049] 1A to 1D show diagrams of a first light-emitting device in a light-emitting device according to one embodiment of the present invention. The light-emitting device is provided on a substrate 100 with an insulating layer 120 having an insulating plane interposed therebetween. FIG. 1 shows an example in which the light-emitting device includes an anode 101, an EL layer (a first hole-injection layer 111, a first hole-transport layer 112, a first light-emitting layer 113, a first electron-transport layer 114, and a first electron-injection layer 115), and a cathode 102. Note that these are merely examples, and layers other than the first light-emitting layer 113 and the first electron-transport layer 114 may or may not be provided, or a layer having multiple functions may be formed instead. Examples of layers other than these include a carrier block layer and an excitation block layer. Furthermore, a transistor, a capacitor, a wiring, and the like for driving the light-emitting device may be provided between the insulating layer 120 and the substrate 100.

[0050] In FIG. 1A, the edge of the anode 101 is covered by an insulating layer 121 .

[0051] The first light-emitting device is fabricated by photolithography, patterning and etching the organic layers. Since patterning and etching are performed after the formation of the first electron transport layer 114 and before the formation of the electron injection layer 115, the edges of the first hole injection layer 111, the first hole transport layer 112, the first light-emitting layer 113, and the first electron transport layer 114 are generally aligned. This means that the edges are also generally aligned when viewed perpendicularly to the substrate or the insulating plane of the insulating layer 120 formed thereon. Furthermore, since the electron injection layer 115 and the cathode 102 are formed later, they cover the edges of the first hole injection layer 111, the first hole transport layer 112, the first light-emitting layer 113, and the first electron transport layer 114.

[0052] FIG. 1B shows a configuration in which the insulating layer 120 formed in FIG. 1A is not formed. The absence of the insulating layer 120 allows for the fabrication of a light-emitting device with higher resolution and a higher aperture ratio. FIG. 1C shows a configuration in which patterning and etching are performed after the cathode 102 is fabricated, and the cathode 102 and electron injection layer 115 are also separated for each light-emitting device. In this configuration, the separation of the light-emitting devices makes it easier to prevent defects such as short circuits and crosstalk. FIG. 1D shows a configuration in which insulating layers 125 and 126 are provided on the side surfaces of the organic layer. In this configuration, the presence of insulating layers 125 and 126 makes it easier to prevent defects such as short circuits and crosstalk, as well as deterioration of the organic layer.

[0053] In the first light-emitting device of the light-emitting device according to one embodiment of the present invention, patterning and etching are performed after the formation of the first electron-transport layer 114, and therefore, the heat resistance of the first electron-transport layer 114 is important. In one embodiment of the present invention, the first electron-transport layer 114 is composed of a first heteroaromatic compound having at least a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, thereby improving the heat resistance of the first electron-transport layer 114. Therefore, even when patterning is performed by photolithography at an appropriate temperature, the progression of crystallization can be suppressed, and a high-definition light-emitting device with excellent characteristics can be obtained.

[0054] The first electron transport layer 114 preferably contains a first heteroaromatic compound having a first heteroaromatic ring, because the electron transport property is improved. Furthermore, it is also preferable for the first organic compound to have a heteroaromatic ring, because the electron transport property is further improved. In the electron transport layer, the heteroaromatic ring is often responsible for electron transport. Therefore, it is preferable that the heteroaromatic ring of the first organic compound is the same as the first heteroaromatic ring, so that the first organic compound does not interfere with electron transport in the electron transport layer. The first electron transport layer 114 is preferably configured from the first heteroaromatic compound and the first organic compound, because this allows for easy fabrication of a light-emitting device.

[0055] In addition, it is preferable that the first heteroaromatic compound and the first organic compound are each contained in the first electron transport layer 114 in an amount of 10% or more, preferably 20% or more, and more preferably 30% or more, since this significantly improves the heat resistance.

[0056] In addition, when the first heteroaromatic ring of the first heteroaromatic compound is a fused heteroaromatic ring, thermal properties such as the glass transition temperature (Tg) are improved, but in a single film of the first heteroaromatic compound, the molecular interactions are strong, making it difficult to form a completely glassy state, resulting in a problem of crystallization occurring over time even at temperatures below Tg. However, in one embodiment of the present invention, even if the first heteroaromatic ring is a fused heteroaromatic ring, its crystallization can be suppressed by the influence of the first organic compound. In other words, the glass transition temperature can be improved while also preventing the film from crystallizing below Tg. Therefore, it is preferable that the first heteroaromatic ring is a fused heteroaromatic ring.

[0057] Furthermore, the first heteroaromatic ring is preferably a π-electron-deficient heteroaromatic ring, and the first heteroaromatic compound is preferably one or more of an organic compound containing a heteroaromatic ring having a polyazole skeleton, an organic compound containing a heteroaromatic ring having a diazine skeleton, and an organic compound containing a heteroaromatic ring having a triazine skeleton.

[0058] Note that the light-emitting device of one embodiment of the present invention can narrow the gap between adjacent light-emitting devices by patterning the light-emitting devices using photolithography. In a light-emitting device manufactured using a metal mask, it is difficult to reduce the gap between the EL layers of adjacent light-emitting devices to less than 10 μm. However, in the light-emitting device of one embodiment of the present invention, the gap can be reduced to 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. For example, by using an exposure tool for LSIs, the gap can be reduced to 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less. This significantly reduces the area of ​​non-light-emitting regions that may exist between two adjacent light-emitting devices. For example, the aperture ratio can be 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more.

[0059] The second light emitting device adjacent to the first light emitting device also has a similar or similar configuration to the first light emitting device.

[0060] Furthermore, since the second light-emitting device is also fabricated by patterning and etching the organic layers using photolithography, the edges of the hole injection layer, hole transport layer, light-emitting layer, and electron transport layer are generally aligned.

[0061] The electron transport layer in the second light-emitting device is also composed of a second heteroaromatic compound having a second heteroaromatic ring and a second organic compound different from the second heteroaromatic compound, thereby improving the heat resistance of the electron transport layer, and therefore, even when patterning is performed by photolithography at an appropriate temperature, the progression of crystallization can be suppressed, resulting in a high-resolution light-emitting device with excellent characteristics.

[0062] The second electron transport layer has good electron transport properties when it contains a second heteroaromatic compound having a second heteroaromatic ring. Furthermore, it is preferable that the second organic compound also has a heteroaromatic ring, since this further improves the electron transport properties. In the electron transport layer, the heteroaromatic ring is often responsible for electron transport. Therefore, it is preferable that the heteroaromatic ring of the second organic compound is the same as the second heteroaromatic ring so that the second organic compound does not interfere with electron transport in the electron transport layer. Furthermore, it is preferable that the second electron transport layer is composed of a second heteroaromatic compound and a second organic compound, since this allows for easy fabrication of a light-emitting device.

[0063] In addition, it is preferable that the second heteroaromatic compound and the second organic compound are each contained in the second electron transport layer in an amount of 10% or more, preferably 20% or more, and more preferably 30% or more, since this significantly improves the heat resistance.

[0064] In addition, when the second heteroaromatic ring of the second heteroaromatic compound is a fused heteroaromatic ring, thermal properties such as the glass transition temperature (Tg) are improved, but in a single film of the second heteroaromatic compound, the molecular interactions are strong, making it difficult to form a completely glassy state, and there is a problem that crystallization tends to occur over time even at temperatures below Tg. However, in one embodiment of the present invention, even if the second heteroaromatic ring is a fused heteroaromatic ring, its crystallization can be suppressed by the influence of the second organic compound. In other words, while improving the glass transition temperature, the phenomenon of the film crystallizing below Tg can also be prevented. Therefore, it is preferable that the second heteroaromatic ring is a fused heteroaromatic ring.

[0065] Furthermore, the second heteroaromatic ring is preferably a π-electron-deficient heteroaromatic ring, and the second heteroaromatic compound is preferably one or more of an organic compound containing a heteroaromatic ring having a polyazole skeleton, an organic compound containing a heteroaromatic ring having a diazine skeleton, and an organic compound containing a heteroaromatic ring having a triazine skeleton.

[0066] Here, in order to approximate the electron injection / transport properties of the first light-emitting device and the second light-emitting device, it is preferable that the first heteroaromatic ring and the second heteroaromatic ring are the same. Furthermore, if the same material can be used for the first light-emitting device and the second light-emitting device, material costs can be reduced through mass production effects. Therefore, it is preferable that the first heteroaromatic compound and the second heteroaromatic compound are the same. Furthermore, it is preferable that the first organic compound and the second organic compound are the same.

[0067] Alternatively, the first heteroaromatic compound and the first organic compound may be the same, and the second heteroaromatic compound and the second organic compound may be the same, with only the mixing ratio being different. The first electron-transport layer and the second electron-transport layer, the first light-emitting layer and the second light-emitting layer, and other structures of the first light-emitting device and the second light-emitting device may be the same or different. In the light-emitting device of one embodiment of the present invention, the electron-transport layer preferably does not contain a metal complex. Examples of the metal complex include alkaline earth metal complexes and alkali metal complexes, particularly alkali metal quinolinolates or alkaline earth metal quinolinolates.

[0068] Next, a method for fabricating these light-emitting devices will be described. The light-emitting device shown in Figure 1A can be fabricated as shown in Figures 2A to 2H.

[0069] First, an insulating layer 120 having an insulating plane and a conductive film 101f to be the anode 101 are formed on a substrate 100 (FIGS. 2A and 2B).

[0070] Next, the conductive film 101f is patterned and etched to form the anode 101 (FIG. 2C). An insulating film 121f that will become the insulating layer 121 is formed to cover the anode 101 (FIG. 2D). An opening is made in the insulating film 121f to form the insulating layer 121 (FIG. 2E).

[0071] Thereafter, organic layers 111f, 112f, 113f, and 114f, which will become the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, and the electron transport layer 114, are formed by vapor deposition (FIG. 2F). The organic layer 114f is a layer containing a first heteroaromatic compound having at least a first heteroaromatic ring, as described above, and a first organic compound different from the first heteroaromatic compound.

[0072] Subsequently, the organic layers 111f, 112f, 113f, and 114f are patterned and etched by photolithography to form the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, and the electron transport layer 114 (FIG. 2G). During this process, heating is performed to harden the photoresist mask. However, since the electron transport layer 114 contains at least a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, as described above, it has good heat resistance and can be heated at a temperature sufficient to reliably harden the photomask. This allows for the production of a high-resolution light-emitting device. Furthermore, it is possible to fabricate a light-emitting device with good reliability.

[0073] Before applying the photoresist, a protective layer or a sacrificial layer may be formed on the organic layer 114f to reduce damage caused by a solvent, etc. This reduces damage to the electron transport layer 114, making it easier to obtain a light-emitting device with better characteristics.

[0074] Finally, an electron injection layer 115 and a cathode 102 can be formed to produce the light-emitting device shown in FIG. 1A (FIG. 2H).

[0075] Next, a method for manufacturing the light-emitting device shown in Fig. 1B will be described with reference to Fig. 3A to Fig. 3F. First, the process up to the formation of the anode 101 is performed in the same manner as in Fig. 2A to Fig. 2C (Fig. 3A to Fig. 3C).

[0076] Next, organic layers 111f, 112f, 113f, and 114f, which will become the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, and the electron transport layer 114, are formed by vapor deposition (FIG. 3D). The organic layer 114f is a layer containing a first heteroaromatic compound having at least a first heteroaromatic ring, as described above, and a first organic compound different from the first heteroaromatic compound.

[0077] Subsequently, the organic layers 111f, 112f, 113f, and 114f are patterned and etched by photolithography to form the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, and the electron transport layer 114 (FIG. 3E). During this process, heating is performed to harden the photoresist mask. However, since the electron transport layer 114 contains at least a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, as described above, it has good heat resistance and can be heated at a temperature sufficient to reliably harden the photomask. This allows for the production of a high-resolution light-emitting device. Furthermore, it is possible to fabricate a light-emitting device with good reliability.

[0078] Before applying the photoresist, a protective layer or a sacrificial layer may be formed on the organic layer 114f to reduce damage caused by a solvent, etc. This reduces damage to the electron transport layer 114, making it easier to obtain a light-emitting device with better characteristics.

[0079] Finally, an electron injection layer 115 and a cathode 102 are formed to produce the light-emitting device shown in Fig. 1B (Fig. 3F). Note that by further performing patterning and etching by photolithography, it is possible to produce a light-emitting device having a shape as shown in Fig. 3G (Fig. 1C).

[0080] Next, a method for fabricating the light-emitting device shown in FIG. 1D will be described with reference to FIGS. 4A to 4H.

[0081] First, an insulating layer 120 having an insulating plane, a conductive film 101f to be the anode 101, organic layers 111f, 112f, 113f, and 114f to be the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, and the electron transport layer 114, and a sacrificial layer 127 are formed on a substrate 100 ( FIG. 4A ). The organic layer 114f is a layer containing a first heteroaromatic compound having at least a first heteroaromatic ring, as described above, and a first organic compound different from the first heteroaromatic compound.

[0082] Subsequently, the organic layers 111f, 112f, 113f, and 114f and the sacrificial layer 127 are patterned and etched by photolithography to form the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, and the electron transport layer 114 ( FIG. 4B ). During this process, heating is performed to harden the photoresist mask. Because the electron transport layer 114 contains at least a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, as described above, it has good heat resistance and can be heated at a temperature sufficient to reliably harden the photomask. This allows for the production of a high-resolution light-emitting device. Furthermore, it is possible to fabricate a light-emitting device with good reliability.

[0083] Thereafter, the conductive film 101f is patterned and etched by photolithography or the like to form the anode 101 (FIG. 4C). Note that the mask used to etch the anode 101 may be the same mask used to etch the organic layer.

[0084] Subsequently, insulating films 125f and 126f are formed to become the insulating layer 125 and the insulating layer 126. The insulating films 125f and 126f are preferably inorganic insulating films.

[0085] Thereafter, anisotropic etching is performed to remove the insulating film 126f, leaving only the insulating film 126f present on the side surfaces of the organic layer, thereby forming the insulating layer 126 (FIG. 4E).

[0086] Next, the exposed insulating film 125f is removed to form the insulating layer 125 (FIG. 4F), and further the exposed sacrificial layer 127 is removed to expose the electron transport layer 114 (FIG. 4G).

[0087] Finally, an electron injection layer 115 and a cathode 102 can be formed to produce the light-emitting device shown in FIG. 1D (FIG. 4H).

[0088] 30A to 30D show diagrams illustrating a tandem light-emitting device, which is another structure of the first light-emitting device in the light-emitting device of one embodiment of the present invention. Note that description of the same structure as that of the light-emitting device shown in FIGS. 1A to 1D may be omitted.

[0089] The light-emitting device is provided on a substrate 100 via an insulating layer 120 having an insulating plane, and in FIG. 1 is a light-emitting device having a tandem structure composed of an anode 101, an EL layer (light-emitting unit A 151a, intermediate layer 150, light-emitting unit B 151b), and a cathode 102. The light-emitting unit A 151a has at least a light-emitting layer A 113a, and the light-emitting unit B 151b has at least a light-emitting layer B 113b and an electron-transporting layer B 114b. In addition, a transistor, a capacitor, wiring, and the like for driving the light-emitting device may be provided between the insulating layer 120 and the substrate 100.

[0090] In FIG. 30A, the end of the anode 101 is covered with an insulating layer 121 .

[0091] The light-emitting device is fabricated by photolithography through patterning and etching of organic layers. Since patterning and etching are performed after forming the electron transport layer B 114b in the light-emitting unit B 151b and before forming the electron injection layer B 115b, the edges of the light-emitting unit A 151a, the intermediate layer 150, and the first light-emitting unit B 151b are generally aligned. Naturally, the edges of the multiple organic layers included in the light-emitting unit A 151a and the multiple organic layers included in the light-emitting unit B 151b are also generally aligned, and the edges of the light-emitting layer A 113a in the light-emitting unit A 151a and the electron transport layer B 114b included in the light-emitting unit B 151b are also generally aligned. This means that the edges are also generally aligned when viewed perpendicular to the substrate or the insulating plane of the insulating layer 120 formed thereon. Furthermore, since the electron injection layer B 115b and the cathode 102 of the light-emitting unit B are formed later, they cover the ends of the light-emitting unit A 151a, the intermediate layer 150, and the light-emitting unit B 151b.

[0092] Figure 30B shows a configuration in which the insulating layer 120 formed in Figure 30A is not formed. The absence of the insulating layer 120 allows for the fabrication of a light-emitting device with higher resolution and a higher aperture ratio. Figure 30C shows a configuration in which patterning and etching are performed after the cathode 102 is fabricated, and the cathode 102 and electron transport layer 115 are also separated for each light-emitting device. In this configuration, the separation of the light-emitting devices makes it easier to prevent defects such as short circuits and crosstalk. Figure 30D shows a configuration in which insulating layers 125 and 126 are provided on the side surfaces of the organic layer. In this configuration, the presence of insulating layers 125 and 126 makes it easier to prevent defects such as short circuits and crosstalk, as well as deterioration of the organic layer.

[0093] In the first light-emitting device of the light-emitting device of one embodiment of the present invention, the first electron-transport layer B 114b is patterned and etched after its formation, so the heat resistance of the first electron-transport layer B 114b is important. In one embodiment of the present invention, the first electron-transport layer B 114b is composed of a first heteroaromatic compound having at least a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, thereby improving the heat resistance of the first electron-transport layer B 114b. Therefore, even when patterning is performed by photolithography at an appropriate temperature, the progression of crystallization can be suppressed, and a high-resolution light-emitting device with excellent characteristics can be obtained.

[0094] The first electron transport layer B 114b preferably contains a first heteroaromatic compound having a first heteroaromatic ring, because this improves the electron transport properties. Furthermore, it is also preferable for the first organic compound to also contain a heteroaromatic ring, because this further improves the electron transport properties. In the electron transport layer, the heteroaromatic ring is often responsible for electron transport. Therefore, it is preferable that the heteroaromatic ring of the first organic compound is the same as the first heteroaromatic ring, so that the first organic compound does not interfere with electron transport in the electron transport layer. The first electron transport layer B 114b is preferably configured from a first heteroaromatic compound and a first organic compound, because this allows for easy fabrication of a light-emitting device.

[0095] In addition, it is preferable that the first heteroaromatic compound and the first organic compound are each contained in the first electron transport layer B 114b in an amount of 10% or more, preferably 20% or more, and more preferably 30% or more, since this significantly improves the heat resistance.

[0096] In addition, when the first heteroaromatic ring of the first heteroaromatic compound is a fused heteroaromatic ring, thermal properties such as the glass transition temperature (Tg) are improved, but in a single film of the first heteroaromatic compound, the molecular interactions are strong, making it difficult to form a completely glassy state, resulting in a problem of crystallization occurring over time even at temperatures below Tg. However, in one embodiment of the present invention, even if the first heteroaromatic ring is a fused heteroaromatic ring, its crystallization can be suppressed by the influence of the first organic compound. In other words, the glass transition temperature can be improved while also preventing the film from crystallizing below Tg. Therefore, it is preferable that the first heteroaromatic ring is a fused heteroaromatic ring.

[0097] Furthermore, the first heteroaromatic ring is preferably a π-electron-deficient heteroaromatic ring, and the first heteroaromatic compound is preferably one or more of an organic compound containing a heteroaromatic ring having a polyazole skeleton, an organic compound containing a heteroaromatic ring having a diazine skeleton, and an organic compound containing a heteroaromatic ring having a triazine skeleton.

[0098] Note that the light-emitting device of one embodiment of the present invention can narrow the gap between adjacent light-emitting devices by patterning the light-emitting devices using photolithography. In a light-emitting device manufactured using a metal mask, it is difficult to reduce the gap between the EL layers of adjacent light-emitting devices to less than 10 μm. However, in the light-emitting device of one embodiment of the present invention, the gap can be reduced to 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. For example, by using an exposure tool for LSIs, the gap can be reduced to 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less. This significantly reduces the area of ​​non-light-emitting regions that may exist between two adjacent light-emitting devices. For example, the aperture ratio can be 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more.

[0099] The second light-emitting device adjacent to the first light-emitting device also has a similar or identical configuration to the first light-emitting device. The first light-emitting device is a light-emitting device with a tandem structure, having a configuration in which at least a second anode, a second EL layer (a second light-emitting unit A, a second intermediate layer, a second light-emitting unit B), and a cathode 102 are stacked in this order. The second light-emitting unit A has at least a second light-emitting layer A, and the second light-emitting unit B has at least a second light-emitting layer B and a second electron-transporting layer B. The second electron-transporting layer B is located between the second light-emitting layer B and the cathode.

[0100] Furthermore, since the second light-emitting device is also fabricated by patterning and etching the organic layer using a photolithography method, the ends of the second light-emitting unit A, the second intermediate layer, and the second light-emitting unit B have shapes that are roughly aligned.

[0101] The second electron transport layer B in the second light-emitting device is also composed of a second heteroaromatic compound having a second heteroaromatic ring and a second organic compound different from the second heteroaromatic compound, thereby improving the heat resistance of the electron transport layer, and therefore suppressing the progression of crystallization even when patterning is performed by photolithography at an appropriate temperature, thereby enabling a high-resolution light-emitting device with excellent characteristics to be obtained.

[0102] The second electron transport layer B has good electron transport properties when it contains a second heteroaromatic compound having a second heteroaromatic ring. Furthermore, it is preferable that the second organic compound also has a heteroaromatic ring, since this further improves the electron transport properties. In the electron transport layer, the heteroaromatic ring is often responsible for electron transport. Therefore, it is preferable that the heteroaromatic ring of the second organic compound is the same as the second heteroaromatic ring so that the second organic compound does not interfere with electron transport in the electron transport layer. Furthermore, it is preferable that the second electron transport layer B is composed of a second heteroaromatic compound and a second organic compound, since this allows for easy fabrication of a light-emitting device.

[0103] In addition, it is preferable that the second heteroaromatic compound and the second organic compound are each contained in the second electron transport layer B in an amount of 10% or more, preferably 20% or more, and more preferably 30% or more, since this significantly improves the heat resistance.

[0104] In addition, when the second heteroaromatic ring of the second heteroaromatic compound is a fused heteroaromatic ring, thermal properties such as the glass transition temperature (Tg) are improved, but in a single film of the second heteroaromatic compound, the molecular interactions are strong, making it difficult to form a completely glassy state, and there is a problem that crystallization tends to occur over time even at temperatures below Tg. However, in one embodiment of the present invention, even if the second heteroaromatic ring is a fused heteroaromatic ring, its crystallization can be suppressed by the influence of the second organic compound. In other words, while improving the glass transition temperature, the phenomenon of the film crystallizing below Tg can also be prevented. Therefore, it is preferable that the second heteroaromatic ring is a fused heteroaromatic ring.

[0105] Furthermore, the second heteroaromatic ring is preferably a π-electron-deficient heteroaromatic ring, and the second heteroaromatic compound is preferably one or more of an organic compound containing a heteroaromatic ring having a polyazole skeleton, an organic compound containing a heteroaromatic ring having a diazine skeleton, and an organic compound containing a heteroaromatic ring having a triazine skeleton.

[0106] Here, in order to approximate the electron injection / transport properties of the first light-emitting device and the second light-emitting device, it is preferable that the first heteroaromatic ring and the second heteroaromatic ring are the same. Furthermore, if the same material can be used for the first light-emitting device and the second light-emitting device, material costs can be reduced through mass production effects. Therefore, it is preferable that the first heteroaromatic compound and the second heteroaromatic compound are the same. Furthermore, it is preferable that the first organic compound and the second organic compound are the same.

[0107] Alternatively, the first heteroaromatic compound and the first organic compound may be the same, and the second heteroaromatic compound and the second organic compound may be the same, with only the mixing ratio being different.

[0108] The first electron transport layer B and the second electron transport layer B, the first light-emitting layer A and the second light-emitting layer A, the first light-emitting layer B and the second light-emitting layer B, and other configurations of the first light-emitting device and the second light-emitting device may be the same or different.

[0109] Note that in the light-emitting device of one embodiment of the present invention, the electron-transport layer preferably does not contain a metal complex, such as an alkaline earth metal complex or an alkali metal complex, particularly an alkali metal quinolinolate or an alkaline earth metal quinolinolate.

[0110] Next, a method for fabricating these light-emitting devices will be described. The light-emitting device shown in Fig. 30A can be fabricated as shown in Figs. 31A to 31H.

[0111] In the first light-emitting device of the light-emitting device according to one embodiment of the present invention, the first electron-transport layer B 114b is patterned and etched after its formation, so the heat resistance of the first electron-transport layer B 114b is important. In one embodiment of the present invention, the first electron-transport layer B 114b is composed of a first heteroaromatic compound having at least a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, thereby improving the heat resistance of the first electron-transport layer B 114b. Therefore, even when patterning is performed by photolithography at an appropriate temperature, the progression of crystallization can be suppressed, and a high-resolution light-emitting device with excellent characteristics can be obtained.

[0112] The first electron transport layer B 114b preferably contains a first heteroaromatic compound having a first heteroaromatic ring, because this improves the electron transport properties. Furthermore, it is also preferable for the first organic compound to also contain a heteroaromatic ring, because this further improves the electron transport properties. In the electron transport layer, the heteroaromatic ring is often responsible for electron transport. Therefore, it is preferable that the heteroaromatic ring of the first organic compound is the same as the first heteroaromatic ring, so that the first organic compound does not interfere with electron transport in the electron transport layer. The first electron transport layer B 114b is preferably configured from a first heteroaromatic compound and a first organic compound, because this allows for easy fabrication of a light-emitting device.

[0113] In addition, it is preferable that the first heteroaromatic compound and the first organic compound are each contained in the first electron transport layer B 114b in an amount of 10% or more, preferably 20% or more, and more preferably 30% or more, since this significantly improves the heat resistance.

[0114] In addition, when the first heteroaromatic ring of the first heteroaromatic compound is a fused heteroaromatic ring, thermal properties such as the glass transition temperature (Tg) are improved, but in a single film of the first heteroaromatic compound, the molecular interactions are strong, making it difficult to form a completely glassy state, resulting in a problem of crystallization occurring over time even at temperatures below Tg. However, in one embodiment of the present invention, even if the first heteroaromatic ring is a fused heteroaromatic ring, its crystallization can be suppressed by the influence of the first organic compound. In other words, the glass transition temperature can be improved while also preventing the film from crystallizing below Tg. Therefore, it is preferable that the first heteroaromatic ring is a fused heteroaromatic ring.

[0115] Furthermore, the first heteroaromatic ring is preferably a π-electron-deficient heteroaromatic ring, and the first heteroaromatic compound is preferably one or more of an organic compound containing a heteroaromatic ring having a polyazole skeleton, an organic compound containing a heteroaromatic ring having a diazine skeleton, and an organic compound containing a heteroaromatic ring having a triazine skeleton.

[0116] Note that the light-emitting device of one embodiment of the present invention can narrow the gap between adjacent light-emitting devices by patterning the light-emitting devices using photolithography. In a light-emitting device manufactured using a metal mask, it is difficult to reduce the gap between the EL layers of adjacent light-emitting devices to less than 10 μm. However, in the light-emitting device of one embodiment of the present invention, the gap can be reduced to 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. For example, by using an exposure tool for LSIs, the gap can be reduced to 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less. This significantly reduces the area of ​​non-light-emitting regions that may exist between two adjacent light-emitting devices. For example, the aperture ratio can be 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more.

[0117] The second light-emitting device adjacent to the first light-emitting device also has a similar or identical configuration to the first light-emitting device. The first light-emitting device is a light-emitting device with a tandem structure, having a configuration in which at least a second anode, a second EL layer (a second light-emitting unit A, a second intermediate layer, a second light-emitting unit B), and a cathode 102 are stacked in this order. The second light-emitting unit A has at least a second light-emitting layer A, and the second light-emitting unit B has at least a second light-emitting layer B and a second electron-transporting layer B. The second electron-transporting layer 2 is located between the second light-emitting layer B and the cathode.

[0118] Furthermore, since the second light-emitting device is also fabricated by patterning and etching the organic layer using a photolithography method, the ends of the second light-emitting unit A, the second intermediate layer, and the second light-emitting unit B have shapes that are roughly aligned.

[0119] The second electron transport layer B in the second light-emitting device is also composed of a second heteroaromatic compound having a second heteroaromatic ring and a second organic compound different from the second heteroaromatic compound, thereby improving the heat resistance of the electron transport layer, and therefore suppressing the progression of crystallization even when patterning is performed by photolithography at an appropriate temperature, thereby enabling a high-resolution light-emitting device with excellent characteristics to be obtained.

[0120] The second electron transport layer B has good electron transport properties when it contains a second heteroaromatic compound having a second heteroaromatic ring. Furthermore, it is preferable that the second organic compound also has a heteroaromatic ring, since this further improves the electron transport properties. In the electron transport layer, the heteroaromatic ring is often responsible for electron transport. Therefore, it is preferable that the heteroaromatic ring of the second organic compound is the same as the second heteroaromatic ring so that the second organic compound does not interfere with electron transport in the electron transport layer. Furthermore, it is preferable that the second electron transport layer B is composed of a second heteroaromatic compound and a second organic compound, since this allows for easy fabrication of a light-emitting device.

[0121] In addition, it is preferable that the second heteroaromatic compound and the second organic compound are each contained in the second electron transport layer B in an amount of 10% or more, preferably 20% or more, and more preferably 30% or more, since this significantly improves the heat resistance.

[0122] In addition, when the second heteroaromatic ring of the second heteroaromatic compound is a fused heteroaromatic ring, thermal properties such as the glass transition temperature (Tg) are improved, but in a single film of the second heteroaromatic compound, the molecular interactions are strong, making it difficult to form a completely glassy state, and there is a problem that crystallization tends to occur over time even at temperatures below Tg. However, in one embodiment of the present invention, even if the second heteroaromatic ring is a fused heteroaromatic ring, its crystallization can be suppressed by the influence of the second organic compound. In other words, while improving the glass transition temperature, the phenomenon of the film crystallizing below Tg can also be prevented. Therefore, it is preferable that the second heteroaromatic ring is a fused heteroaromatic ring.

[0123] Furthermore, the second heteroaromatic ring is preferably a π-electron-deficient heteroaromatic ring, and the second heteroaromatic compound is preferably one or more of an organic compound containing a heteroaromatic ring having a polyazole skeleton, an organic compound containing a heteroaromatic ring having a diazine skeleton, and an organic compound containing a heteroaromatic ring having a triazine skeleton.

[0124] Here, in order to approximate the electron injection / transport properties of the first light-emitting device and the second light-emitting device, it is preferable that the first heteroaromatic ring and the second heteroaromatic ring are the same. Furthermore, if the same material can be used for the first light-emitting device and the second light-emitting device, material costs can be reduced through mass production effects. Therefore, it is preferable that the first heteroaromatic compound and the second heteroaromatic compound are the same. Furthermore, it is preferable that the first organic compound and the second organic compound are the same.

[0125] Alternatively, the first heteroaromatic compound and the first organic compound may be the same, and the second heteroaromatic compound and the second organic compound may be the same, with only the mixing ratio being different.

[0126] The first electron transport layer B and the second electron transport layer B, the first light-emitting layer A and the second light-emitting layer A, the first light-emitting layer B and the second light-emitting layer B, and other configurations of the first light-emitting device and the second light-emitting device may be the same or different.

[0127] Note that in the light-emitting device of one embodiment of the present invention, the electron-transport layer preferably does not contain a metal complex, such as an alkaline earth metal complex or an alkali metal complex, particularly an alkali metal quinolinolate or an alkaline earth metal quinolinolate.

[0128] Next, a method for fabricating these light-emitting devices will be described. The light-emitting device shown in Fig. 30A can be fabricated as shown in Figs. 31A to 31H.

[0129] First, an insulating layer 120 having an insulating plane and a conductive film 101f to become the anode 101 are formed on a substrate 100 (FIGS. 31A and 31B).

[0130] Next, the conductive film 101f is patterned and etched to form the anode 101 (FIG. 31C). An insulating film 121f that will become the insulating layer 121 is formed to cover the anode 101 (FIG. 31D). An opening is made in the insulating film 121f to form the insulating layer 121 (FIG. 31E).

[0131] Then, organic layers 151af, 150f, and 151bf (including 144bf) that will become light-emitting unit A 151a, intermediate layer 150, and light-emitting unit B 151b (including electron transport layer B 114b) are formed by vapor deposition (FIG. 31F). As described above, organic layer 114bf is a layer that contains a first heteroaromatic compound having at least a first heteroaromatic ring and a first organic compound that is different from the first heteroaromatic compound.

[0132] Subsequently, the organic layers 151af, 150f, and 151bf (including 144bf) are patterned and etched by photolithography to form the light-emitting unit A 151a, the intermediate layer 150, and the light-emitting unit B 151b (including the electron transport layer B 114b) ( FIG. 31G ). During this process, heating is performed to harden the photoresist mask. Because the electron transport layer B 114b contains at least a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, as described above, it has good heat resistance and can be heated at a temperature sufficient to reliably harden the photomask. This allows for the production of a high-resolution light-emitting device. Furthermore, it is possible to fabricate a highly reliable light-emitting device.

[0133] Before applying the photoresist, a protective layer or a sacrificial layer may be formed on the organic layer 114bf to reduce damage caused by a solvent, etc. This reduces damage to the electron transport layer B 114b, making it easier to obtain a light-emitting device with better characteristics.

[0134] Finally, an electron injection layer B 115b and a cathode 102 are formed to complete the light-emitting device shown in FIG. 30A (FIG. 31H).

[0135] Next, a method for fabricating the light-emitting device shown in Fig. 30B will be described with reference to Fig. 32A to Fig. 32F. First, the process up to the formation of the anode 101 is performed in the same manner as in Fig. 31A to Fig. 31C (Fig. 32A to Fig. 32C).

[0136] Next, organic layers 151af, 150f, and 151bf (including 144bf) that will become light-emitting unit A 151a, intermediate layer 150, and light-emitting unit B 151b (including electron transport layer B 114b) are formed by vapor deposition (FIG. 32D). As described above, organic layer 114bf is a layer that contains a first heteroaromatic compound having at least a first heteroaromatic ring and a first organic compound that is different from the first heteroaromatic compound.

[0137] Subsequently, the organic layers 151af, 150f, and 151bf (including 144bf) are patterned and etched by photolithography to form the light-emitting unit A 151a, the intermediate layer 150, and the light-emitting unit B 151b (including the electron transport layer B 114b) ( FIG. 32E ). During this process, heating is performed to harden the photoresist mask. Because the electron transport layer B 114b contains at least a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, as described above, it has good heat resistance and can be heated at a temperature sufficient to reliably harden the photomask. This allows for the production of a high-resolution light-emitting device. Furthermore, it is possible to fabricate a light-emitting device with good reliability.

[0138] Before applying the photoresist, a protective layer or a sacrificial layer may be formed on the organic layer 114bf to reduce damage caused by a solvent, etc. This reduces damage to the electron transport layer B 114b, making it easier to obtain a light-emitting device with better characteristics.

[0139] Finally, an electron injection layer B 115b and a cathode 102 are formed to produce the light-emitting device shown in Fig. 1B (Fig. 32F). Note that by further performing patterning and etching by photolithography, it is possible to produce a light-emitting device having a shape as shown in Fig. 32G (Fig. 30C).

[0140] Next, a method for fabricating the light-emitting device shown in FIG. 30D will be described with reference to FIGS. 33A to 33H.

[0141] First, an insulating layer 120 having an insulating plane, a conductive film 101f to be the anode 101, an light-emitting unit A 151a, an intermediate layer 150, organic layers 151af, 150f, and 151bf (including 144bf) to be the light-emitting unit B 151b (including the electron transport layer B 114b), and a sacrificial layer 127 are formed on a substrate 100 ( FIG. 33A ). The organic layer 114bf is a layer containing a first heteroaromatic compound having at least a first heteroaromatic ring, as described above, and a first organic compound different from the first heteroaromatic compound.

[0142] Subsequently, the organic layers 151af, 150f, and 151bf (including 144bf) and the sacrificial layer 127 are patterned and etched by photolithography to form the light-emitting unit A 151a, the intermediate layer 150, the light-emitting unit B 151b (including the electron transport layer B 114b), and the sacrificial layer 127 ( FIG. 33B ). During this process, heating is performed to harden the photoresist mask. Because the electron transport layer B 114b contains at least a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, as described above, it has good heat resistance and can be heated at a temperature sufficient to reliably harden the photomask. This allows for the production of a high-resolution light-emitting device. Furthermore, it is possible to fabricate a light-emitting device with good reliability.

[0143] Thereafter, the conductive film 101f is patterned and etched by photolithography or the like to form the anode 101 (FIG. 33C). Note that the mask used to etch the anode 101 may be the mask created to etch the organic layer.

[0144] Subsequently, insulating films 125f and 126f are formed to become the insulating layer 125 and the insulating layer 126. The insulating films 125b and 126b are preferably inorganic insulating films.

[0145] Thereafter, anisotropic etching is performed to remove the insulating film 126f, leaving only the insulating film 126f present on the side surfaces of the organic layer, thereby forming the insulating layer 126 (FIG. 33E).

[0146] Next, the exposed insulating film 125f is removed to form the insulating layer 125 (FIG. 33F), and further the exposed sacrificial layer 127 is removed to expose the electron transport layer B 114b (FIG. 33G).

[0147] Finally, an electron injection layer B 115b and a cathode 102 can be formed to produce the light-emitting device shown in FIG. 30D (FIG. 33H).

[0148] Next, an example of a tandem-structure element configuration will be described in detail using Figures 34A and 34B. As described above, the light-emitting device has an EL layer 103 (light-emitting unit A 151a, intermediate layer 150, light-emitting unit B 151b, and electron injection layer B 115b) between an anode 101 and a cathode 102. Furthermore, light-emitting unit A 151a has, in order from the anode 101 side, a hole injection layer A 111a, a hole transport layer A 112a, a light-emitting layer A 113a, and an electron transport layer A 114a, and light-emitting unit B 151b has a hole transport layer B 112b, a light-emitting layer B 113b, and an electron transport layer B 114b.

[0149] In the light-emitting device of one embodiment of the present invention, after the electron-transport layer B 114b is formed, patterning and etching are performed by photolithography to process the light-emitting unit A, the intermediate layer, and the light-emitting unit B into desired shapes. In this case, the electron-transport layer B 114b includes a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound. This improves heat resistance and increases the temperature that can be withstood in heat treatment during resist mask formation, enabling higher-resolution patterning. Furthermore, the reliability of the light-emitting device is improved.

[0150] The electron transport layer B 114b and the electron transport layer A 114a may have the same or different structures. When the electron transport layer A 114a has the same structure as the electron transport layer B 114b, a light-emitting device with better heat resistance can be obtained. Furthermore, when the electron transport layer A 114a is formed of one type of organic compound, it is advantageous in terms of manufacturing costs.

[0151] FIG. 34B is a diagram schematically illustrating a first light-emitting device 110_1 and a second light-emitting device 110_2 that are adjacent light-emitting devices.

[0152] The first light-emitting device 110_1 includes a first light-emitting unit A 151a1, a first intermediate layer 150_1, a first light-emitting unit B 151b1, and an electron injection layer B 115b (common layer) between a first anode 101_1 and a cathode 102 (common layer).

[0153] The first light-emitting unit A 151a1 has, in order from the first anode 101_1 side, a first hole injection layer A 111a1, a first hole transport layer A 112a1, a first light-emitting layer 113a1, and a first electron transport layer A 114a1, and the first light-emitting unit B 151b1 has a first hole transport layer B 112b1, a first light-emitting layer B 113b1, and a first electron transport layer B 114b1.

[0154] In the light-emitting device of one embodiment of the present invention, after the first electron-transport layer B 114b1 is formed, patterning and etching are performed by photolithography to process the first light-emitting unit A 151a1, the first intermediate layer 150_1, and the first light-emitting unit B 151b1 into desired shapes. Therefore, the edges of the first light-emitting unit A 151a1, the first intermediate layer 150_1, and the first light-emitting unit B 151b1 are generally aligned. Of course, the edges of the multiple organic layers included in the first light-emitting unit A 151a1 and the multiple organic layers included in the first light-emitting unit B 151b1 are also generally aligned, and the edges of the first light-emitting layer A 113a1 of the first light-emitting unit A 151a1 and the first electron-transport layer B 114b1 included in the first light-emitting unit B 151b1 are also generally aligned. This means that the ends of the substrate and the insulating layer 120 formed thereon are also substantially aligned when viewed in a direction perpendicular to the insulating plane of the substrate or the insulating layer 120 formed thereon.

[0155] Furthermore, the first electron transport layer B 114b includes a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, which improves heat resistance and increases the temperature that can withstand heat treatment during resist mask formation, enabling higher-resolution patterning. The reliability of the light-emitting device is also improved. It is preferable that the first aromatic compound and the first organic compound are both contained in the first electron transport layer B 114b1 in an amount of 10% by weight or more, preferably 20% by weight or more, and more preferably 30% by weight or more.

[0156] The second light-emitting unit A 151a2 has, in order from the second anode 101_2 side, a second hole injection layer A 111a2, a second hole transport layer A 112a2, a second light-emitting layer 113a2, and a second electron transport layer A 114a2, and the second light-emitting unit B 151b2 has a second hole transport layer B 112b2, a second light-emitting layer B 113b2, and a second electron transport layer B 114b2.

[0157] In the light-emitting device of one embodiment of the present invention, after the second electron-transport layer B 114b1 is formed, patterning and etching are performed by photolithography to process the second light-emitting unit A 151a2, the second intermediate layer 150_2, and the second light-emitting unit B 151b2 into desired shapes. Therefore, the edges of the second light-emitting unit A 151a2, the second intermediate layer 150_2, and the second light-emitting unit B 151b2 are generally aligned. Of course, the edges of the multiple organic layers included in the second light-emitting unit A 151a2 and the multiple organic layers included in the second light-emitting unit B 151b2 are also generally aligned, and the edges of the second light-emitting layer A 113a2 of the second light-emitting unit A 151a2 and the second electron-transport layer B 114b2 included in the second light-emitting unit B 151b2 are also generally aligned. This means that the ends of the substrate and the insulating layer 120 formed thereon are also substantially aligned when viewed in a direction perpendicular to the insulating plane of the substrate or the insulating layer 120 formed thereon.

[0158] Furthermore, the second electron transport layer B 114b includes a second heteroaromatic compound having a second heteroaromatic ring and a second organic compound different from the second heteroaromatic compound, thereby improving heat resistance and increasing the temperature that can withstand heat treatment during resist mask formation, enabling higher-resolution patterning. Furthermore, the reliability of the light-emitting device is also improved. It is preferable that the second aromatic compound and the second organic compound are both contained in the second electron transport layer B 114b2 in an amount of 10% by weight or more, preferably 20% by weight or more, and more preferably 30% by weight or more.

[0159] Here, it is preferable that the first heteroaromatic ring of the first heteroaromatic compound contained in the first electron transport layer B 114b1 is the same as the second heteroaromatic ring of the second heteroaromatic compound contained in the second electron transport layer B 114b2, and it is more preferable that the first heteroaromatic compound and the second heteroaromatic compound are the same.

[0160] In addition, it is preferable that the first organic compound contained in the first electron transport layer B 114b1 and the second organic compound contained in the second electron transport layer B 114b2 are the same.

[0161] [Light-Emitting Device] An example of a light-emitting device according to one embodiment of the present invention using the above light-emitting device will be described below.

[0162] 5A is a schematic top view of a display device 400 according to one embodiment of the present invention. The display device 400 includes a plurality of red light-emitting devices 110R, a plurality of green light-emitting devices 110G, and a plurality of blue light-emitting devices 110B. In FIG. 5A, the light-emitting regions of the light-emitting devices are labeled with R, G, and B to easily distinguish the light-emitting devices from one another.

[0163] The light-emitting devices 110R, 110G, and 110B are arranged in a matrix. Fig. 5A shows a so-called stripe arrangement in which light-emitting devices of the same color are arranged in one direction. Note that the arrangement of the light-emitting devices is not limited to this, and other arrangements such as a delta arrangement or a zigzag arrangement may also be used, or a pentile arrangement may also be used.

[0164] The light emitting devices 110R, 110G, and 110B are arranged in the X direction. In the Y direction intersecting the X direction, light emitting devices of the same color are arranged.

[0165] The light emitting device 110R, the light emitting device 110G, and the light emitting device 110B are light emitting devices having the above-described configuration.

[0166] Fig. 5B is a schematic cross-sectional view corresponding to dashed-dotted line A1-A2 in Fig. 5A, and Fig. 5C is a schematic cross-sectional view corresponding to dashed-dotted line B1-B2 in Fig. 5A. Fig. 5B shows cross sections of light-emitting device 110R, light-emitting device 110G, and light-emitting device 110B. Light-emitting device 110R has an anode 101R, an EL layer 103R, an EL layer (corresponding to an electron injection layer or electron injection layer B) 115, and a cathode 102. Light-emitting device 110G has an anode 101G, an EL layer 103G, an EL layer (corresponding to an electron injection layer or electron injection layer B) 115, and a cathode 102. Light-emitting device 110B has an anode 101B, an EL layer 103B, an EL layer (corresponding to an electron injection layer or electron injection layer B) 115, and a cathode 102. The EL layer 415 and the cathode 102 are provided in common to the light-emitting device 110R, the light-emitting device 110G, and the light-emitting device 110B. The EL layer 415 can also be called a common layer.

[0167] The EL layer 103R of the light-emitting device 110R contains a light-emitting organic compound that emits light having an intensity in at least the red wavelength range. The EL layer 103G of the light-emitting device 110G contains a light-emitting organic compound that emits light having an intensity in at least the green wavelength range. The EL layer 103B of the light-emitting device 110B contains a light-emitting organic compound that emits light having an intensity in at least the blue wavelength range.

[0168] The adjacent first and second light-emitting devices correspond to, for example, light-emitting device 110R and light-emitting device 110G, light-emitting device 110G and light-emitting device 110B, etc. In addition, light-emitting devices of the same color arranged vertically in Fig. 5A can also be considered adjacent light-emitting devices.

[0169] The EL layer 103R, the EL layer 103G, and the EL layer 103B may each include one or more of an electron-injection layer, an electron-transport layer, a hole-injection layer, a hole-transport layer, a carrier-blocking layer, an exciton-blocking layer, and the like, in addition to a layer containing a light-emitting organic compound (light-emitting layer). The EL layer 415 may not include a light-emitting layer. In the light-emitting device of one embodiment of the present invention, the EL layer 415 is preferably an electron-injection layer. Note that when the electron-transport layer also serves as an electron-injection layer, the EL layer 415 is not necessarily provided.

[0170] Alternatively, the EL layer 103R, the EL layer 103G, and the EL layer 103B each include a light-emitting unit A, an intermediate layer, and a light-emitting unit B. The light-emitting unit A includes at least a light-emitting layer A, and the light-emitting unit B includes at least a light-emitting layer B and an electron-transport layer B. In addition to these, the EL layer 415 may include one or more of an electron-injection layer, an electron-transport layer, a hole-injection layer, a hole-transport layer, a carrier-blocking layer, an exciton-blocking layer, and the like. The EL layer 415 may not include a light-emitting layer. In the light-emitting device of one embodiment of the present invention, the EL layer 415 is preferably an electron-injection layer. Note that when the electron-transport layer B also serves as an electron-injection layer, the EL layer 415 is not necessarily provided.

[0171] The anode 101R, the anode 101G, and the anode 101B are provided for each light-emitting device. The cathode 102 and the EL layer 415 are provided as a continuous layer common to each light-emitting device. A conductive film that is translucent to visible light is used for either the pixel electrode or the cathode 102, and a conductive film that is reflective is used for the other. By making each pixel electrode translucent and the cathode 102 reflective, a bottom-emission display device can be obtained. Conversely, by making each pixel electrode reflective and the cathode 102 translucent, a top-emission display device can be obtained. Note that by making both the pixel electrode and the cathode 102 translucent, a dual-emission display device can also be obtained.

[0172] An insulating layer 131 is provided to cover the ends of the anode 101R, the anode 101G, and the anode 101B. The ends of the insulating layer 131 are preferably tapered. Note that the insulating layer 131 does not have to be provided if it is not necessary.

[0173] The EL layer 103R, the EL layer 103G, and the EL layer 103B each have a region in contact with the upper surface of the pixel electrode and a region in contact with the surface of the insulating layer 131. In addition, the ends of the EL layer 103R, the EL layer 103G, and the EL layer 103B are located on the insulating layer 131.

[0174] 5B, a gap is provided between the two EL layers between light-emitting devices of different colors. In this manner, it is preferable that the EL layers 103R, 103G, and 103G are arranged so as not to contact each other. This effectively prevents current from flowing through two adjacent EL layers, which would otherwise cause unintended light emission. This improves contrast and realizes a display device with high display quality.

[0175] 5C shows an example in which the EL layer 103R is formed in a strip shape so that the EL layer 103R is continuous in the Y direction. By forming the EL layer 103R and the like in a strip shape, space to separate them is not required, and the area of ​​the non-light-emitting region between the light-emitting devices can be reduced, thereby increasing the aperture ratio. Note that while FIG. 5C shows a cross section of the light-emitting device 110R as an example, the light-emitting device 110G and the light-emitting device 110B can also have a similar shape. Note that the EL layer may be separated for each light-emitting device in the Y direction.

[0176] An insulating layer 121 is provided on the cathode 102 to cover the light-emitting device 110R, the light-emitting device 110G, and the light-emitting device 110B. The insulating layer 121 has a function of preventing impurities such as water from diffusing from above into each light-emitting device.

[0177] The insulating layer 121 may have, for example, a single-layer structure or a stacked-layer structure including at least an inorganic insulating film. Examples of the inorganic insulating film include oxide films or nitride films such as a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, an aluminum oxynitride film, and a hafnium oxide film. Alternatively, the insulating layer 121 may be made of a semiconductor material such as indium gallium oxide or indium gallium zinc oxide.

[0178] Alternatively, the insulating layer 121 may be a laminated film of an inorganic insulating film and an organic insulating film. For example, a configuration in which an organic insulating film is sandwiched between a pair of inorganic insulating films is preferable. Furthermore, it is preferable that the organic insulating film functions as a planarizing film. This allows the upper surface of the organic insulating film to be flat, thereby improving the coverage of the inorganic insulating film thereon and enhancing the barrier properties. Furthermore, since the upper surface of the insulating layer 121 is flat, when a structure (e.g., a color filter, a touch sensor electrode, a lens array, or the like) is provided above the insulating layer 121, the influence of uneven shapes caused by the structure below can be reduced, which is preferable.

[0179] 5A also shows a connection electrode 101C that is electrically connected to the cathode 102. The connection electrode 101C is given a potential (e.g., an anode potential or a cathode potential) to be supplied to the cathode 102. The connection electrode 101C is provided outside the display area where the light-emitting devices 110R and the like are arranged. In addition, in FIG. 5A, the cathode 102 is shown by a dashed line.

[0180] The connection electrode 101C can be provided along the periphery of the display area. For example, it may be provided along one side of the periphery of the display area, or it may be provided over two or more sides of the periphery of the display area. That is, when the top surface shape of the display area is rectangular, the top surface shape of the connection electrode 101C can be strip-shaped, L-shaped, U-shaped (square bracket-shaped), square-shaped, or the like.

[0181] Fig. 5D is a schematic cross-sectional view corresponding to dashed line C1-C2 in Fig. 5A. Fig. 5D shows connection portion 130 where connection electrode 101C and cathode 102 are electrically connected. In connection portion 130, cathode 102 is provided in contact with connection electrode 101C, and insulating layer 121 is provided covering cathode 102. In addition, insulating layer 131 is provided covering the end of connection electrode 101C.

[0182] [Manufacturing Method Example 1] An example of a manufacturing method of a display device according to one embodiment of the present invention will be described below with reference to the drawings. Here, the display device 400 shown in the above configuration example will be described as an example. FIGS. 6A to 6F are cross-sectional schematic views illustrating steps in a manufacturing method of a display device exemplified below. Also, in FIG. 6A and other drawings, a cross-sectional schematic view of the connection portion 130 and its vicinity is also shown on the right side.

[0183] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, etc. CVD methods include a plasma enhanced chemical vapor deposition (PECVD) method and a thermal CVD method. One type of thermal CVD method is a metal organic chemical vapor deposition (MOCVD) method.

[0184] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, knife coating, etc.

[0185] Furthermore, when processing the thin film that constitutes the display device, a photolithography method or the like can be used. Alternatively, the thin film may be processed by a nanoimprint method, a sandblasting method, a lift-off method, or the like. Furthermore, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0186] There are two typical photolithography methods: one is to form a resist mask on the thin film to be processed, process the thin film by etching or the like, and then remove the resist mask; the other is to form a photosensitive thin film, and then process the thin film into the desired shape by exposure and development.

[0187] In photolithography, the light used for exposure may be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, ArF laser light, etc. Exposure may also be performed by immersion exposure technology. Extreme ultraviolet (EUV) light, X-rays, etc. may also be used as light for exposure. An electron beam may also be used instead of light for exposure. Extreme ultraviolet light, X-rays, or an electron beam are preferred because they enable extremely fine processing. When exposure is performed by scanning a beam such as an electron beam, a photomask is not required.

[0188] For etching the thin film, dry etching, wet etching, sandblasting, or the like can be used.

[0189] [Preparation of Substrate 100] A substrate having heat resistance sufficient to withstand at least subsequent heat treatment can be used as the substrate 100. When an insulating substrate is used as the substrate 100, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like can be used. In addition, a semiconductor substrate such as a single crystal semiconductor substrate made of silicon, silicon carbide, or the like, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, or an SOI substrate can be used.

[0190] In particular, it is preferable to use a substrate in which a semiconductor circuit including semiconductor elements such as transistors is formed on the semiconductor substrate or insulating substrate as the substrate 100. The semiconductor circuit preferably constitutes, for example, a pixel circuit, a gate line driving circuit (gate driver), a source line driving circuit (source driver), etc. In addition to the above, an arithmetic circuit, a memory circuit, etc. may also be constituted.

[0191] [Formation of anodes 101R, 101G, 101B, and connection electrode 101C] Next, the anodes 101R, 101G, 101B, and connection electrode 101C are formed on the substrate 100. First, a conductive film that will become the anodes (pixel electrodes) is formed, a resist mask is formed by photolithography, and unnecessary portions of the conductive film are removed by etching. Then, the resist mask is removed, thereby forming the anodes 101R, 101G, and 101B.

[0192] When a conductive film reflective to visible light is used as each pixel electrode, it is preferable to use a material (e.g., silver or aluminum) with as high a reflectivity as possible across the entire wavelength range of visible light. This not only increases the light extraction efficiency of the light-emitting device but also improves color reproducibility. When a conductive film reflective to visible light is used as each pixel electrode, a so-called top-emission light-emitting device can be obtained, in which light is extracted in the direction away from the substrate. When a light-transmitting conductive film is used as each pixel electrode, a so-called bottom-emission light-emitting device can be obtained, in which light is extracted toward the substrate.

[0193] [Formation of Insulating Layer 121] Next, an insulating layer 121 is formed to cover the edges of the anode 101R, anode 101G, and anode 101B ( FIG. 6A ). An organic insulating film or an inorganic insulating film can be used as the insulating layer 121. The insulating layer 121 preferably has tapered edges to improve step coverage of the subsequent EL layer. In particular, when using an organic insulating film, it is preferable to use a photosensitive material, as this makes it easier to control the edge shape by adjusting the exposure and development conditions. Note that if the insulating layer 121 is not provided, the distance between light-emitting devices can be further reduced, resulting in a higher-definition light-emitting device.

[0194] [Formation of EL Layer 103Rf] Subsequently, an EL layer 103Rf, which will later become the EL layer 103R, is formed on the anode 101R, the anode 101G, the anode 101B, and the insulating layer 121.

[0195] The EL layer 103Rf includes a film containing at least a light-emitting compound. In addition, the EL layer 103Rf may have a structure in which one or more films functioning as an electron injection layer, an electron transport layer, a charge generation layer, a hole transport layer, or a hole injection layer are stacked.

[0196] In the case of a tandem light-emitting device, the EL layer 103Rf has at least an emitting unit A, an intermediate layer, and an emitting unit B, in this order from the anode side. The emitting unit A includes at least an emitting layer A, and the emitting unit B has at least an emitting layer B and an electron transport layer B, with the electron transport layer B being located furthest from the anode 101 in the EL layer 103Rf. In addition to the emitting layers of the emitting units A and B, the EL layer 103Rf may have one or more of an electron injection layer, an electron transport layer, a hole injection layer, a hole transport layer, a carrier blocking layer, an exciton blocking layer, etc. Note that, since the intermediate layer can serve as both an electron injection layer and a hole injection layer, the electron injection layer of the emitting unit A and the hole injection layer of the emitting unit B may not be provided.

[0197] The EL layer 103Rf can be formed by, for example, evaporation, sputtering, ink-jet printing, etc. However, the present invention is not limited to this, and the above-mentioned film formation methods can be used appropriately.

[0198] For example, the EL layer 103Rf is preferably a stacked film in which a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer are stacked in this order. In this case, a film including the electron injection layer 115 can be used as the EL layer to be formed later. In the light-emitting device according to one embodiment of the present invention, providing an electron transport layer to cover the light-emitting layer can prevent the light-emitting layer from being damaged in a subsequent photolithography process or the like, thereby enabling the manufacture of a highly reliable light-emitting device. Furthermore, by forming the electron transport layer as a layer including at least a first heteroaromatic compound having a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound, heat resistance is improved, and the temperature that can withstand a heat treatment during the formation of a resist mask to be formed later is increased, enabling higher-resolution patterning. Furthermore, the reliability of the light-emitting device is also improved.

[0199] The EL layer 103Rf is preferably formed so as not to be provided on the connection electrode 101C. For example, when the EL layer 103Rf is formed by evaporation (or sputtering), it is preferable to form the EL layer 103Rf using a shielding mask or to remove unnecessary portions on the connection electrode 101C in a subsequent etching step so that the EL layer 103Rf is not formed on the connection electrode 101C.

[0200] [Formation of Sacrificial Film 144a] Subsequently, the sacrificial film 144a is formed to cover the EL layer 103Rf. The sacrificial film 144a is provided in contact with the upper surface of the connection electrode 101C.

[0201] The sacrificial film 144a can be a film that is highly resistant to etching of each EL layer, such as the EL layer 103Rf, i.e., a film with a large etching selectivity. The sacrificial film 144a can also be a film that has a large etching selectivity with respect to a protective film, such as the protective film 146a described below. Furthermore, the sacrificial film 144a can be a film that can be removed by wet etching, which causes little damage to each EL layer.

[0202] The sacrificial film 144a may be, for example, a metal film, an alloy film, a metal oxide film, a semiconductor film, an inorganic insulating film, etc. The sacrificial film 144a may be formed by various film formation methods such as a sputtering method, a vapor deposition method, a CVD method, an ALD method, etc.

[0203] The sacrificial film 144a may be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing such a metal material. In particular, it is preferable to use a low-melting-point material such as aluminum or silver.

[0204] The sacrificial film 144a may be made of a metal oxide such as indium gallium zinc oxide (In—Ga—Zn oxide, also referred to as IGZO). Other examples include indium oxide, indium zinc oxide (In—Zn oxide), indium tin oxide (In—Sn oxide), indium titanium oxide (In—Ti oxide), indium tin zinc oxide (In—Sn—Zn oxide), indium titanium zinc oxide (In—Ti—Zn oxide), and indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide). Alternatively, indium tin oxide containing silicon may be used.

[0205] The present invention can also be applied to a case where, instead of the gallium, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) is used. In particular, it is preferable that M is one or more elements selected from gallium, aluminum, and yttrium.

[0206] The sacrificial film 144a may be made of an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide.

[0207] Furthermore, it is preferable to use a material that can dissolve in a chemically stable solvent for the sacrificial film 144a, at least for the film located at the top of the EL layer 103Rf. In particular, a material that dissolves in water or alcohol is suitable for use in the sacrificial film 144a. When forming the sacrificial film 144a, it is preferable to apply the material dissolved in a solvent such as water or alcohol using a wet film formation method, and then perform a heat treatment to evaporate the solvent. In this case, performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature and in a short time, thereby reducing thermal damage to the EL layer 103Rf.

[0208] Wet film formation methods that can be used to form the sacrificial film 144a include spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, and knife coating.

[0209] The sacrificial film 144a may be made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinyl pyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin.

[0210] [Formation of Protective Film 146a] Subsequently, a protective film 146a is formed on the sacrificial film 144a (FIG. 6B).

[0211] The protective film 146a is a film that is used as a hard mask when etching the sacrificial film 144a later. Furthermore, when processing the protective film 146a later, the sacrificial film 144a is exposed. Therefore, a combination of films that have a large etching selectivity relative to each other is selected for the sacrificial film 144a and the protective film 146a. Therefore, a film that can be used for the protective film 146a can be selected depending on the etching conditions for the sacrificial film 144a and the etching conditions for the protective film 146a.

[0212] For example, when dry etching using a gas containing fluorine (also referred to as a fluorine-based gas) is used to etch the protective film 146a, silicon, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum, tantalum nitride, an alloy containing molybdenum and niobium, an alloy containing molybdenum and tungsten, or the like can be used for the protective film 146a. Here, examples of films that can achieve a large etching selectivity (i.e., a slower etching rate) compared to dry etching using the fluorine-based gas include metal oxide films such as IGZO and ITO, which can be used for the sacrificial film 144a.

[0213] However, the protective film 146a is not limited to this, and can be selected from various materials depending on the etching conditions of the sacrificial film 144a and the etching conditions of the protective film 146a. For example, it can be selected from the films that can be used for the sacrificial film 144a.

[0214] The protective film 146a may be, for example, a nitride film, such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, or germanium nitride.

[0215] Alternatively, an oxide film can be used as the protective film 146a. Typically, an oxide film or an oxynitride film such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, or hafnium oxynitride can be used.

[0216] Alternatively, the protective film 146a may be an organic film that can be used for the EL layer 103Rf, etc. For example, the same organic film as that used for the EL layer 103Rf, EL layer 103Gf, or EL layer 103Bf may be used for the protective film 146a. Using such an organic film is preferable because it allows the same film formation equipment to be used for the EL layer 103Rf, etc.

[0217] [Formation of Resist Mask 143a] Subsequently, resist masks 143a are formed on the protective film 146a at positions overlapping the anode 101R and the connection electrode 101C (FIG. 6C).

[0218] The resist mask 143a can be made of a resist material containing a photosensitive resin, such as a positive resist material or a negative resist material.

[0219] Here, if the resist mask 143a is formed on the sacrificial film 144a without the protective film 146a, there is a risk that the EL layer 103Rf will be dissolved by the solvent of the resist material if there are defects such as pinholes in the sacrificial film 144a. By using the protective film 146a, it is possible to prevent such problems from occurring.

[0220] When the sacrificial film 144a is made of a film that is less likely to have defects such as pinholes, the resist mask 143a may be formed directly on the sacrificial film 144a without using the protective film 146a.

[0221] [Etching of Protective Film 146a] Subsequently, a portion of the protective film 146a that is not covered by the resist mask 143a is removed by etching to form a strip-shaped protective layer 147a. At the same time, the protective layer 147a is also formed on the connection electrode 101C.

[0222] When etching the protective film 146a, it is preferable to use etching conditions with a high selectivity so that the sacrificial film 144a is not removed by the etching. The protective film 146a can be etched by wet etching or dry etching, but using dry etching can prevent the pattern of the protective film 146a from shrinking.

[0223] [Removal of Resist Mask 143a] Subsequently, the resist mask 143a is removed (FIG. 6D).

[0224] The resist mask 143a can be removed by wet etching or dry etching. In particular, the resist mask 143a is preferably removed by dry etching (also called plasma ashing) using oxygen gas as an etching gas.

[0225] At this time, the resist mask 143a is removed in a state in which the EL layer 103Rf is covered with the sacrificial film 144a, so that the influence on the EL layer 103Rf is suppressed. In particular, if the EL layer 103Rf comes into contact with oxygen, it may have an adverse effect on the electrical characteristics, so this is suitable for performing etching using oxygen gas, such as plasma ashing.

[0226] [Etching of Sacrificial Film 144a] Next, using the protective layer 147a as a mask, a portion of the sacrificial film 144a that is not covered by the protective layer 147a is removed by etching to form a strip-shaped sacrificial layer 145a (FIG. 6E). At the same time, the sacrificial layer 145a is also formed on the connection electrode 101C.

[0227] The sacrificial film 144a can be etched by wet etching or dry etching, but dry etching is preferable because it can prevent the pattern from shrinking.

[0228] [Etching of EL layer 103Rf and protective layer 147a] Next, the protective layer 147a is etched, and at the same time, a portion of the EL layer 103Rf that is not covered by the sacrificial layer 145a is removed by etching to form a strip-shaped EL layer 103R (FIG. 6F). At this time, the protective layer 147a on the connection electrode 101C is also removed.

[0229] By etching the EL layer 103Rf and the protective layer 147a by the same treatment, the process can be simplified and the manufacturing cost of the display device can be reduced, which is preferable.

[0230] In particular, it is preferable to use dry etching using an etching gas that does not contain oxygen as a main component for etching the EL layer 103Rf. This makes it possible to suppress deterioration of the EL layer 103Rf and realize a highly reliable display device. Examples of etching gases that do not contain oxygen as a main component include CF４ , C ４ F ８ , S.F. ６ , CHF ３ , Cl ２ , H ２ O, BCl ３ , H ２ Alternatively, a noble gas such as He may be used. Also, a mixed gas of the above gas and a dilution gas that does not contain oxygen may be used as the etching gas.

[0231] The EL layer 103Rf and the protective layer 147a may be etched separately. In this case, the EL layer 103Rf may be etched first, or the protective layer 147a may be etched first.

[0232] At this point, the EL layer 103R and the connection electrode 101C are covered with the sacrificial layer 145a.

[0233] [Formation of EL layer 103Gf] Next, the EL layer 103Gf, which will later become the EL layer 103G, is formed on the sacrificial layer 145a, the insulating layer 121, the anode 101G, and the anode 101B. At this time, similar to the EL layer 103Rf, it is preferable that the EL layer 103Gf is not provided on the connection electrode 101C.

[0234] The method for forming the EL layer 103Gf can be similar to that described for the EL layer 103Rf.

[0235] [Formation of Sacrificial Film 144b] Subsequently, the sacrificial film 144b is formed on the EL layer 103Gf. The sacrificial film 144b can be formed by the same method as the sacrificial film 144a. In particular, it is preferable to use the same material for the sacrificial film 144b as for the sacrificial film 144a.

[0236] At the same time, a sacrificial film 144a is formed on the connection electrode 101C, covering the sacrificial layer 145a.

[0237] [Formation of Protective Film 146b] Next, the protective film 146b is formed on the sacrificial film 144b. The protective film 146b can be formed by the same method as the protective film 146a. In particular, it is preferable that the protective film 146b is made of the same material as the protective film 146a.

[0238] [Formation of Resist Mask 143b] Subsequently, a resist mask 143b is formed on the protective film 146b in a region overlapping with the anode 101G and a region overlapping with the connection electrode 101C (FIG. 7A).

[0239] The resist mask 143b can be formed in the same manner as the resist mask 143a.

[0240] [Etching of Protective Film 146b] Subsequently, a portion of the protective film 146b that is not covered by the resist mask 143b is removed by etching to form a strip-shaped protective layer 147b (FIG. 7B). At the same time, the protective layer 147b is also formed on the connection electrode 101C.

[0241] The above description of the protective film 146a can be applied to the etching of the protective film 146b.

[0242] [Removal of Resist Mask 143b] Subsequently, the resist mask 143a is removed. The above description of the resist mask 143a can be applied to the removal of the resist mask 143b.

[0243] [Etching of Sacrificial Film 144b] Next, using the protective layer 147b as a mask, a portion of the sacrificial film 144b that is not covered by the protective layer 147b is removed by etching to form a strip-shaped sacrificial layer 145b. At the same time, a sacrificial layer 145b is also formed on the connection electrode 101C. A sacrificial layer 145a and a sacrificial layer 145b are stacked on the connection electrode 101C.

[0244] The above description of the sacrificial film 144a can be applied to the etching of the sacrificial film 144b.

[0245] [Etching of EL layer 103Gf and protective layer 147b] Next, the protective layer 147b is etched, and at the same time, a portion of the EL layer 103Gf that is not covered by the sacrificial layer 145b is removed by etching to form a strip-shaped EL layer 103G (FIG. 7C). At this time, the protective layer 147b on the connection electrode 101C is also removed.

[0246] The above description of the EL layer 103Rf and the protective layer 147a can be applied to the etching of the EL layer 103Gf and the protective layer 147b.

[0247] At this time, since the EL layer 103R is protected by the sacrificial layer 145a, it is possible to prevent the EL layer 103R from being damaged in the etching process of the EL layer 103Gf.

[0248] In this manner, the strip-shaped EL layers 103R and the strip-shaped EL layers 103G can be separately formed with high positional accuracy.

[0249] [Formation of EL Layer 103B] By performing the above steps on the EL layer 103Bf (not shown), it is possible to form an island-shaped EL layer 103B and an island-shaped sacrificial layer 145c (FIG. 7D).

[0250] That is, after the EL layer 103G is formed, the EL layer 103Bf, the sacrificial film 144c, the protective film 146c, and the resist mask 143c (none of which are shown) are formed in this order. The protective film 146c is then etched to form a protective layer 147c (not shown), and the resist mask 143c is then removed. The sacrificial film 144c is then etched to form a sacrificial layer 145c. The protective layer 147c and the EL layer 103Bf are then etched to form the strip-shaped EL layer 103B.

[0251] After the EL layer 103B is formed, a sacrificial layer 145c is also formed on the connection electrode 101C at the same time. A sacrificial layer 145a, a sacrificial layer 145b, and a sacrificial layer 145c are stacked on the connection electrode 101C.

[0252] [Removal of Sacrificial Layers] Next, the sacrificial layers 145a, 145b, and 145c are removed to expose the upper surfaces of the EL layers 103R, 103G, and 103B (FIG. 7E). At the same time, the upper surface of the connection electrode 101C is also exposed.

[0253] The sacrificial layers 145a, 145b, and 145c can be removed by wet etching or dry etching. At this time, it is preferable to use a method that causes as little damage as possible to the EL layers 103R, 103G, and 103B. In particular, it is preferable to use a wet etching method. For example, it is preferable to use wet etching using a tetramethylammonium hydroxide solution (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0254] Alternatively, the sacrificial layers 145a, 145b, and 145c are preferably removed by dissolving them in a solvent such as water or alcohol. Here, various alcohols such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin can be used as the alcohol that can dissolve the sacrificial layers 145a, 145b, and 145c.

[0255] After removing the sacrificial layers 145a, 145b, and 145c, it is preferable to perform drying treatment to remove water contained inside the EL layers 103R, 103G, and 103B and water adsorbed on their surfaces. For example, it is preferable to perform heat treatment in an inert gas atmosphere or a reduced-pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50° C. or higher and 200° C. or lower, preferably 60° C. or higher and 150° C. or lower, and more preferably 70° C. or higher and 120° C. or lower. A reduced-pressure atmosphere is preferable because it enables drying at a lower temperature.

[0256] In this manner, the EL layer 103R, the EL layer 103G, and the EL layer 103B can be separately produced.

[0257] The electron transport layers included in the EL layer 103R, the EL layer 103G, and the EL layer 103B may have the same or different structures. The heteroaromatic rings of the heteroaromatic compounds included in the electron transport layers are preferably the same, and the heteroaromatic compounds included in the electron transport layers are preferably the same. The organic compounds included in the electron transport layers are preferably the same.

[0258] [Formation of Electron Injection Layer 115] Subsequently, the electron injection layer 115 or the electron injection layer B 115b is formed to cover the EL layer 103R, the EL layer 103G, and the EL layer 103B.

[0259] The electron injection layer 115 or the electron transport layer B 115b can be formed by the same method as the EL layer 103Rf, etc. When the electron injection layer 115 is formed by a vapor deposition method, it is preferable to form the layer using a shielding mask so that the electron injection layer 115 is not formed on the connection electrode 101C.

[0260] [Formation of Cathode 102] Subsequently, the cathode 102 is formed to cover the electron injection layer 115 or the electron transport layer B 115b and the connection electrode 101C (FIG. 7F).

[0261] The cathode 102 can be formed by a film formation method such as evaporation or sputtering. Alternatively, a film formed by evaporation and a film formed by sputtering may be laminated. In this case, the cathode 102 is preferably formed so as to encompass the region where the electron injection layer 115 or the electron transport layer B 115b is formed. That is, the edge of the electron injection layer 115 or the electron transport layer B 115b can be configured to overlap the cathode 102. The cathode 102 is preferably formed using a shielding mask. The cathode 102 is electrically connected to the connection electrode 101C outside the display region.

[0262] [Formation of Protective Layer] Next, a protective layer is formed on the cathode 102. For depositing the inorganic insulating film used for the protective layer, it is preferable to use a sputtering method, a PECVD method, or an ALD method. In particular, the ALD method is preferable because it has excellent step coverage and is less likely to cause defects such as pinholes. For depositing the organic insulating film, it is preferable to use an inkjet method because it can form a uniform film in a desired area.

[0263] Through the above steps, a light-emitting device of one embodiment of the present invention can be manufactured.

[0264] In the above description, the cathode 102 and the electron injection layer 115 or the electron transport layer B 115b are formed to have different top surface shapes, but they may be formed in the same region.

[0265] [Configuration Example of Light-Emitting Device] Next, other examples of the structure and materials of the light-emitting device in the light-emitting device of one embodiment of the present invention will be described. The light-emitting device in the light-emitting device of one embodiment of the present invention shown in FIG. 1 includes an EL layer 103 composed of multiple layers between a pair of electrodes, an anode 101 and a cathode 102, as described above. The EL layer 103 includes a light-emitting layer 113 containing a light-emitting material and an electron-transport layer 114 having the above-described structure. Note that the EL layer 103 may include a hole-injection layer, a hole-transport layer, a light-emitting layer, an electron-transport layer, an electron-injection layer, a carrier-blocking layer, an exciton-blocking layer, and the like. The configuration of layers other than the above-described essential layers can be freely selected and used depending on the required performance.

[0266] Furthermore, the light-emitting device in the light-emitting device of one embodiment of the present invention as shown in Figure 30 is a light-emitting device having a tandem structure in which the EL layer 103 (light-emitting unit A 151a, intermediate layer 150, light-emitting unit B 151b, and electron-transport layer B 115b) is provided between a pair of electrodes, i.e., the anode 101 and the cathode 102, as described above.

[0267] The light-emitting unit A 151a has at least the light-emitting layer A 113a, and the light-emitting unit B 151b has at least the light-emitting layer B 113b and the electron-transport layer B 114b. Each light-emitting unit may have a hole-injection layer, a hole-transport layer, a light-emitting layer, an electron-transport layer, an electron-injection layer, a carrier-blocking layer, an exciton-blocking layer, etc., and the configuration of layers other than the essential layers described above can be freely selected depending on the required performance. In addition, the intermediate layer may also function as the electron-injection layer for the light-emitting unit A and the hole-injection layer for the light-emitting unit B.

[0268] The anode 101 is preferably formed using a metal, alloy, conductive compound, or mixture thereof having a large work function (specifically, 4.0 eV or more). Specific examples include indium oxide-tin oxide (ITO), indium oxide-tin oxide containing silicon or silicon oxide, indium oxide-zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). These conductive metal oxide films are usually formed by sputtering, but may also be formed by applying a sol-gel method or the like. As an example of a fabrication method, indium oxide-zinc oxide can be formed by sputtering using a target in which 1 to 20 wt % zinc oxide is added to indium oxide. Indium oxide containing tungsten oxide and zinc oxide (IWZO) can also be formed by sputtering using a target containing 0.5 to 5 wt % tungsten oxide and 0.1 to 1 wt % zinc oxide relative to indium oxide. Other materials that can be used for the anode 101 include, for example, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), and nitrides of metal materials (e.g., titanium nitride). Alternatively, graphene can be used for the anode 101. By using a composite material (described later) in the layer of the EL layer 103 that contacts the anode 101, electrode materials can be selected regardless of the work function.

[0269] The EL layer 103 preferably has a stacked layer structure, but the stacked layer structure is not particularly limited, and various layer structures such as a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, a carrier blocking layer (hole blocking layer, electron blocking layer), an exciton blocking layer, and an intermediate layer (charge generation layer) can be applied. Note that any of the layers does not necessarily have to be provided. In this embodiment, a structure including a hole injection layer 111 and a hole transport layer 112 in addition to an electron transport layer 114, an electron injection layer 115, and a light-emitting layer 113 as shown in FIGS. 1A to 1D will be specifically described below.

[0270] The hole-injection layer 111 is a layer containing a substance having acceptor properties. As the substance having acceptor properties, either an organic compound or an inorganic compound can be used.

[0271] As the substance having acceptor properties, a compound having an electron-withdrawing group (a halogen group or a cyano group) can be used, and 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F ４ -TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile, etc. In particular, compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having a plurality of heteroatoms, such as HAT-CN, are thermally stable and preferred. In addition, [3]radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluoro groups or cyano groups) are preferred because they have very high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. In addition to the organic compounds mentioned above, other materials that can be used as acceptors include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, and the like. Other examples include phthalocyanine (abbreviated as H ２The hole injection layer 111 can also be formed from a phthalocyanine complex compound such as copper phthalocyanine (CuPc) or copper phthalocyanine (CuPc), an aromatic amine compound such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), or a polymer such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS). A substance having acceptor properties can extract electrons from an adjacent hole transport layer (or hole transport material) when an electric field is applied.

[0272] Furthermore, a composite material in which the above-mentioned acceptor substance is contained in a material having hole transport properties can also be used for the hole injection layer 111. By using a composite material in which an acceptor substance is contained in a material having hole transport properties, a material for forming an electrode can be selected regardless of the work function. That is, not only a material having a high work function but also a material having a low work function can be used for the anode 101. As a material having hole transport properties used for the composite material, various organic compounds such as aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. As a material having hole transport properties used for the composite material, a 1×10 −６ cm ２ A substance having a hole mobility of 1 / Vs or more is preferred. Specific examples of organic compounds that can be used as a material having a hole transport property in a composite material are listed below.

[0273] Examples of aromatic amine compounds that can be used in the composite material include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B). Specific examples of the carbazole derivative include 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole, and Examples of carbazole that can be used include 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenylanthracen-9-yl)phenyl]-9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, and the like.Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert- Examples of suitable anthracene include butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, and 2,5,8,11-tetra(tert-butyl)perylene. In addition, pentacene, coronene, and the like can also be used. The aromatic hydrocarbon having a vinyl group may also have a vinyl skeleton. Examples of the aromatic hydrocarbon having a vinyl group include 4,4′-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA). Note that the organic compound of one embodiment of the present invention can also be used.

[0274] Alternatively, polymer compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used. The hole-transporting material used in the composite material preferably has a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group may be used. In addition, it is preferable that these second organic compounds are substances having an N,N-bis(4-biphenyl)amino group, since it is possible to manufacture a light-emitting device with a good lifetime. Specific examples of the second organic compounds include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4"-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BnfBB1BP), and N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BnfBB1BP). N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4′,4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-diphenyl-4''-( 7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4, 4'-Diphenyl-4''-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4' 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(1,1'-biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-diphenyl-4'-(2-naphthyl)-4''-{9-(4-biphenylyl)carbazole)}triphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(4-biphenylyl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBA SF), N,N-bis(1,1'-biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(1,1'-biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(4-biphenyl)-N-(dibenzofuran-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyl)phenyl]- mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine amine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9′-Bifluoren-2-amine (abbreviation: PCBASF), N-(1,1′-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi-9H-fluoren-4-amine, N,N N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi-9H-fluoren-1-amine, and the like can be mentioned.

[0275] Note that the material having hole-transporting properties used in the composite material is more preferably a substance having a relatively deep HOMO level of -5.7 eV or more and -5.4 eV or less. When the material having hole-transporting properties used in the composite material has a relatively deep HOMO level, injection of holes into the hole-transport layer 112 becomes easy, and a light-emitting device with a long lifetime can be easily obtained. Furthermore, when the material having hole-transporting properties used in the composite material is a substance having a relatively deep HOMO level, induction of holes can be appropriately suppressed, and a light-emitting device with a long lifetime can be obtained.

[0276] The refractive index of the layer can be reduced by further mixing an alkali metal or alkaline earth metal fluoride with the composite material (preferably with a fluorine atom ratio of 20% or more in the layer), which also allows a layer with a low refractive index to be formed inside the EL layer 103, thereby improving the external quantum efficiency of the light-emitting device.

[0277] By forming the hole injection layer 111, the hole injection property becomes good, and a light emitting device with a low driving voltage can be obtained.

[0278] Among substances having acceptor properties, organic compounds having acceptor properties are easy to use because they can be easily vapor-deposited and formed into a film.

[0279] The hole transport layer 112 is formed by containing a material having a hole transport property. −６ cm ２ It is preferable that the material has a hole mobility of 1.0 V or more.

[0280] Examples of the material having a hole transport property include 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine (abbreviation: TPD), 4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), and 4-phenyl-3′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP). 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), compounds having an aromatic amine skeleton such as 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF); 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl carbazole (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(1,1'-biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(1,1'-biphenyl-3-yl)-9'-(1,1'-biphenyl-4-yl)-9H,9'H-3,Compounds having a carbazole skeleton, such as 3'-bicarbazole (abbreviation: mBPCCBP) and 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[ Examples of suitable compounds include compounds having a thiophene skeleton, such as 4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the compounds listed above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole-transport properties, and contribute to reducing driving voltage. The substances listed as materials having hole-transport properties used in the composite material of the hole-injection layer 111 can also be suitably used as materials for the hole-transport layer 112.

[0281] The light-emitting layer 113 contains a light-emitting substance and a host material. The light-emitting layer 113 may also contain other materials. Alternatively, the light-emitting layer 113 may be a laminate of two layers with different compositions.

[0282] The light-emitting substance may be a fluorescent substance, a phosphorescent substance, a substance that exhibits thermally activated delayed fluorescence (TADF), or other light-emitting substances. Note that one embodiment of the present invention is more preferably applicable to the case where the light-emitting layer 113 is a layer that exhibits fluorescent light, particularly a layer that exhibits blue fluorescent light.

[0283] Examples of materials that can be used as the fluorescent substance in the light-emitting layer 113 include the following: In addition, fluorescent substances other than these can also be used.

[0284] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine )phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-( 10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9 -diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAB PhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6 -methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine amine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJ™), N,N'-diphenyl-N,N'-(1,6-pyren-diyl)bis[(6-phenylbenzo[b ]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02). In particular, condensed aromatic diamine compounds typified by pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 are preferred because of their high hole-trapping properties and excellent luminous efficiency and reliability. ,

[0285] When a phosphorescent material is used as the light-emitting material in the light-emitting layer 113, examples of materials that can be used include the following.

[0286] Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp) ３ ]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz) ３ ]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b) ３]), and organometallic iridium complexes having a 4H-triazole skeleton, such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp) ３ ]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me) ３ and organometallic iridium complexes having a 1H-triazole skeleton, such as fac-tris[(1-2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpmi) ３ ]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me) ３ organometallic iridium complexes having an imidazole skeleton, such as bis[2-(4',6'-difluorophenyl)pyridinato-N,C ２’ ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C ２’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C ２’} Iridium(III) picolinate (abbreviation: [Ir(CF ３ ppy) ２ (pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C ２’ ] Organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand, such as iridium(III) acetylacetonate (abbreviation: FIracac), are examples of such compounds that exhibit blue phosphorescence and have an emission peak in the wavelength range of 440 nm to 520 nm.

[0287] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm) ３]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm) ３ ]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm) ２ (acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm) ２ (acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm) ２ (acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm) ２ (acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm) ２ and organometallic iridium complexes having a pyrimidine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me) ２ (acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr) ２ and organometallic iridium complexes having a pyrazine skeleton, such as tris(2-phenylpyridinato-N,C(acac)]). ２’ ) Iridium(III) (abbreviation: [Ir(ppy) ３ ]), bis(2-phenylpyridinato-N,C ２’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(ppy) ２ (acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq) ２ (acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq) ３]), tris(2-phenylquinolinato-N,C ２’ ) Iridium(III) (abbreviation: [Ir(pq) ３ ]), bis(2-phenylquinolinato-N,C ２’ ) iridium(III) acetylacetonate (abbreviation: [Ir(pq) ２ (acac)]), [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3) ２ (mbfpypy-d3)), [2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro 2,[3-b]pyridin-7-yl-κC]bis[5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC]iridium(III) (abbreviation: Ir(5mtpy-d6) ２ (mbfpypy-iPr-d4)), [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy) ２ (mbfpypy-d3)), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy) ２ In addition to organometallic iridium complexes having a pyridine skeleton, such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac) ３ These compounds mainly exhibit green phosphorescence, with an emission peak in the wavelength range of 500 nm to 600 nm. Organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because of their outstanding reliability and luminous efficiency.

[0288] Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm) ２ (dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm) ２ (dpm)]), bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(dpm) ２ and organometallic iridium complexes having a pyrimidine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr) ２ (acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr) ２ (dpm)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq) ２ organometallic iridium complexes having a pyrazine skeleton, such as tris(1-phenylisoquinolinato-N,C(acac)]), ２’ ) Iridium(III) (abbreviation: [Ir(piq) ３ ]), bis(1-phenylisoquinolinato-N,C ２’ ) iridium(III) acetylacetonate (abbreviation: [Ir(piq) ２ In addition to organometallic iridium complexes having a pyridine skeleton such as [(acac)]], platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviation: PtOEP), and tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)] ３ (Phen)]), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA) ３These compounds exhibit red phosphorescence, with an emission peak in the wavelength range of 600 nm to 700 nm. Organometallic iridium complexes having a pyrazine skeleton can emit red light with good chromaticity.

[0289] In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0290] Examples of TADF materials that can be used include fullerene and its derivatives, acridine and its derivatives, and eosin derivatives. Other examples include metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complexes (SnF) represented by the following structural formula: ２ (Proto IX)), mesoporphyrin-tin fluoride complex (SnF ２ (Meso IX)), hematoporphyrin-tin fluoride complex (SnF ２ (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ２ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ２ (OEP)), etioporphyrin-tin fluoride complex (SnF ２ (Etio I)), octaethylporphyrin-platinum chloride complex (PtCl ２ OEP) and the like.

[0291]

[0292] Further, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ) shown in the following structural formula, 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: P Heterocyclic compounds having one or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10′H-spiro[acridine-9,9′-anthracene]-10′-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable.The furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. The pyrrole skeleton is particularly preferably an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton. A substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is particularly preferred because the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-deficient heteroaromatic ring are both enhanced, reducing the energy difference between the S1 level and the T1 level, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. The π-electron-rich skeleton may be, for example, an aromatic amine skeleton or a phenazine skeleton. Examples of usable π-electron-deficient skeletons include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring or heteroaromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton or a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0293]

[0294] The TADF material is a material that has a small difference between the S1 level and the T1 level and has the function of converting triplet excitation energy to singlet excitation energy by reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy (reverse intersystem crossing) with a small amount of thermal energy, and a singlet excited state can be efficiently generated. Furthermore, triplet excitation energy can be converted into luminescence.

[0295] Furthermore, an exciplex (also called an exciplex) that forms an excited state with two types of substances has an extremely small difference between the S1 level and the T1 level, and functions as a TADF material that can convert triplet excitation energy into singlet excitation energy.

[0296] The T1 level can be determined by using a phosphorescence spectrum observed at low temperatures (e.g., 77 K to 10 K). When a tangent line is drawn at the base of the fluorescence spectrum on the short wavelength side of the TADF material, and the energy of the wavelength of the extrapolated line is defined as the S1 level, and when a tangent line is drawn at the base of the phosphorescence spectrum on the short wavelength side of the TADF material, and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between S1 and T1 is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0297] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0298] As the host material of the light-emitting layer, various carrier transporting materials such as a material having an electron transporting property, a material having a hole transporting property, and the above-mentioned TADF material can be used.

[0299] As a material having hole transport properties, an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring is preferable. For example, 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine (abbreviation: TPD), 4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP ... nyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB) , 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), etc. compounds having a carbazole skeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), and 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP); compounds having a carbazole skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Examples of suitable compounds include compounds having a thiophene skeleton, such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the compounds mentioned above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. In addition, the organic compounds listed as examples of the material having hole transport properties for the hole transport layer 112 can also be used.

[0300] Examples of materials having electron transport properties include bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq ２), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), or other metal complexes, or organic compounds having a π-electron-deficient heteroaromatic ring, are preferred. Examples of organic compounds having a π-electron-deficient heteroaromatic ring include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), etc. and organic compounds containing heteroaromatic rings, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mC zBPDBq), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 6-(1,1′-biphenyl-3-yl)-4-[3,organic compounds containing heteroaromatic rings having a diazine skeleton, such as 5-bis(9H-carbazol-9-yl)phenyl)-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(1,1′-biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), and 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz); organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB); 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn); 2-[(1,1'-biphenyl)-4-yl]-4-phenyl-6-[9,9'-spiro Bi(9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo"b"naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo"b"naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 5-[3-(4,6-diphenyl-1,3,5-triazine- 2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-[3'-(triphenylen-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl'1,3,5-triazine (abbreviation: mTpBPTzn), 2-[(1,1'-biphenyl)-4-yl]-4-phenyl-6-[9,9'-spirobi(9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 9-[4-(4,6-diphenyl-1,3,Examples of suitable organic compounds include those containing heteroaromatic rings with a triazine skeleton, such as [5-triazin-2-yl]-2-dibenzothiophenyl]-2-phenyl-9H-carbazole (abbreviation: PCDBfTzn) and 2-[1,1'-biphenyl]-3-yl-4-phenyl-6-(8-[1,1':4',1''-terphenyl]-4-yl-1-dibenzofuranyl)-1,3,5-triazine (abbreviation: mBP-TPDBfTzn). Among the above, organic compounds containing heteroaromatic rings with a diazine skeleton, organic compounds containing heteroaromatic rings with a pyridine skeleton, and organic compounds containing heteroaromatic rings with a triazine skeleton are preferred due to their high reliability. In particular, organic compounds containing heteroaromatic rings with a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing heteroaromatic rings with a triazine skeleton have high electron transport properties and contribute to reduced driving voltage.

[0301] The TADF materials that can be used as the host material can be the same as those listed above. When a TADF material is used as a host material, triplet excitation energy generated in the TADF material is converted into singlet excitation energy by reverse intersystem crossing, and the energy is further transferred to a light-emitting substance, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting substance functions as an energy acceptor.

[0302] This is very effective when the luminescent material is a fluorescent luminescent material. Furthermore, in this case, in order to obtain high luminous efficiency, it is preferable that the S1 level of the TADF material is higher than the S1 level of the fluorescent luminescent material. Furthermore, it is preferable that the T1 level of the TADF material is higher than the S1 level of the fluorescent luminescent material. Therefore, it is preferable that the T1 level of the TADF material is higher than the T1 level of the fluorescent luminescent material.

[0303] It is also preferable to use a TADF material that emits light that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material, since this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient light emission.

[0304] Furthermore, in order to efficiently generate singlet excitation energy from triplet excitation energy through reverse intersystem crossing, it is preferable that carrier recombination occurs in the TADF material. It is also preferable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent material. To this end, it is preferable that the fluorescent material has a protecting group around the luminophore (the skeleton responsible for light emission) possessed by the fluorescent material. The protecting group is preferably a substituent without a π bond, and is preferably a saturated hydrocarbon. Specific examples include alkyl groups having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3 to 10 carbon atoms, and trialkylsilyl groups having 3 to 10 carbon atoms. It is even more preferable that the protecting group has multiple protecting groups. Substituents without a π bond have poor carrier transport function, so the distance between the TADF material and the luminophore of the fluorescent material can be increased without significantly affecting carrier transport or carrier recombination. Here, the luminophore refers to the atomic group (skeleton) responsible for light emission in the fluorescent material. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a fused aromatic ring or a fused heteroaromatic ring. Examples of the fused aromatic ring or the fused heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, and a phenothiazine skeleton. In particular, fluorescent substances having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton are preferred because of their high fluorescence quantum yield.

[0305] When a fluorescent light-emitting substance is used as the light-emitting substance, a material having an anthracene skeleton is suitable as the host material. Using a substance having an anthracene skeleton as the host material for a fluorescent light-emitting substance makes it possible to realize an emitting layer with both excellent luminous efficiency and durability. As a substance having an anthracene skeleton to be used as the host material, a substance having a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton, is preferred because it is chemically stable. Furthermore, a host material having a carbazole skeleton is preferred because it enhances hole injection and transport properties. However, a host material containing a benzocarbazole skeleton in which a benzene ring is further condensed to carbazole is more preferred because its HOMO is shallower by about 0.1 eV than that of carbazole, making it easier for holes to enter. In particular, a host material containing a dibenzocarbazole skeleton is preferred because its HOMO is shallower by about 0.1 eV than that of carbazole, making it easier for holes to enter, and it also has excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). Note that, in view of the hole injection / transport property, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton.Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4′-yl} Anthracene (abbreviation: FLPPA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)-benzo[b] Examples include naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-[4-(10-[,1,1′-biphenyl]-4-yl-9-anthracenyl)phenyl]-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), etc. In particular, CzPA, cgDBCzPA2mBnfPPA, and PCzPA are preferred choices because they exhibit very good properties.

[0306] The host material may be a mixture of a plurality of substances. When a mixture of host materials is used, it is preferable to mix a material having electron transport properties with a material having hole transport properties. By mixing a material having electron transport properties with a material having hole transport properties, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole transport properties to the material having electron transport properties may be 1:19 to 19:1 (material having hole transport properties:material having electron transport properties).

[0307] A phosphorescent material can be used as part of the mixed material. The phosphorescent material can be used as an energy donor that provides excitation energy to a fluorescent material when the fluorescent material is used as a light-emitting material.

[0308] Furthermore, these mixed materials may form an exciplex. It is preferable to select a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, because this allows for smooth energy transfer and efficient light emission. Furthermore, using this structure is also preferable because it reduces the driving voltage.

[0309] At least one of the materials forming the exciplex may be a phosphorescent material, which allows efficient conversion of triplet excitation energy into singlet excitation energy through reverse intersystem crossing.

[0310] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of the material having hole transport properties is equal to or higher than the HOMO level of the material having electron transport properties. Also, it is preferable that the LUMO level of the material having hole transport properties is equal to or higher than the LUMO level of the material having electron transport properties. Note that 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).

[0311] The formation of exciplexes can be confirmed, for example, by comparing the emission spectra of a material having hole transport properties, a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing the phenomenon in which the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak on the longer wavelength side). Alternatively, the formation of exciplexes can be confirmed by comparing the transient photoluminescence (PL) of a material having hole transport properties, the transient PL of a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lifetime component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL may also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of a material having hole transport properties, the transient EL of a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing the differences in transient response.

[0312] As described above, the electron transport layer is formed by containing at least a heteroaromatic compound having a heteroaromatic ring and an organic compound different from the heteroaromatic compound. At least one of the two materials is an organic compound having electron transport properties, and the electron mobility at a square root of an electric field strength [V / cm] of 600 is 1×10 or more. −６ cm ２ A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can be used as long as they have a higher electron transporting property than holes. Note that the organic compound is preferably an organic compound having a π-electron-deficient heteroaromatic ring. The organic compound having a π-electron-deficient heteroaromatic ring is preferably, for example, one or more of an organic compound having a heteroaromatic ring with a polyazole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0313] Specific examples of the organic compound that can be used for the electron transport layer include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]- organic compounds containing a heteroaromatic ring with an azole skeleton, such as 9H-carbazole (abbreviation: CO11), 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and 4,4′-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs); and 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), and the like. organic compounds including 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq),h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)furan phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[(3'- ... 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3 4,6mCzBP2Pm), 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(1,1'-biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py) , 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), organic compounds containing a heteroaromatic ring having a diazine skeleton, such as 2-[3′-(9,9-dimethyl-9H-(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(1,1′-biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), and 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz); -fluoren-2-yl)-1,1′-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 2-[(1,1′-biphenyl)-4-yl]-4-phenyl-6-[9,9′-spirobi(9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo“b”naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo“b”naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-di Methyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris(3'-(pi (3-(2,6-dimethyl-3-pyridyl)-5-(9-phenanthryl)phenyl)-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 11-(4-[1,1′-diphenyl]-4-yl-6-phenyl- 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-[3'-(triphenylen-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl'-1,3,5-triazine (abbreviation: mTpBPTzn), 2-[(1,

[0033] Examples of organic compounds containing a heteroaromatic ring having a triazine skeleton include organic compounds containing a heteroaromatic ring such as 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothiophenyl]-2-phenyl-9H-carbazole (abbreviation: PCDBfTzn), and 2-[1,1'-biphenyl]-3-yl-4-phenyl-6-(8-[1,1':4',1''-terphenyl]-4-yl-1-dibenzofuranyl)-1,3,5-triazine (abbreviation: mBP-TPDBfTzn). Among the above, organic compounds containing a heteroaromatic ring having a diazine skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reducing driving voltage.

[0314] The organic compounds that can be used in the electron transport layer described above include both heteroaromatic compounds having a heteroaromatic ring contained in the electron transport layer or the electron transport layer B, and organic compounds different from the heteroaromatic compounds.

[0315] Although the organic compound different from the heteroaromatic compound may be an organic compound other than the above, it is preferable to use the organic compounds described above as the organic compounds that can be used in the electron transport layer. Note that the electron transport layer 114 having this structure may also serve as the electron injection layer 115.

[0316] Between the electron transport layer 114 and the cathode 102, an electron injection layer 115 is formed using lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ２It is preferable to provide a layer containing an alkali metal or alkaline earth metal, or a compound or complex thereof, such as 8-hydroxyquinolinato-lithium (abbreviation: Liq oxide). The electron-injection layer 115 may be formed by incorporating an alkali metal, alkaline earth metal, or a compound thereof into a layer made of a substance having an electron-transporting property, or may be formed by using an electride. Examples of the electride include a substance in which electrons are added at a high concentration to a mixed oxide of calcium and aluminum.

[0317] The intermediate layer used in the tandem light-emitting device is preferably a charge generation layer. The charge generation layer has the function of injecting electrons into one light-emitting unit and injecting holes into the other light-emitting unit when a voltage is applied between the anode and the cathode. When a voltage is applied so that the potential of the anode is higher than the potential of the cathode, the charge generation layer may inject electrons into light-emitting unit A and holes into light-emitting unit B.

[0318] The charge generation layer includes at least a P-type layer. The P-type layer is preferably formed using the composite material listed above as a material that can be used to form the hole injection layer. The P-type layer may also be formed by laminating a film containing an acceptor material and a film containing a hole transport material, both of which are materials that can form the composite material. By applying a potential to the P-type layer, electrons are injected into the electron transport layer A of the light-emitting unit A and holes are injected into the hole transport layer B of the light-emitting unit B, thereby operating the light-emitting device.

[0319] It is preferable that the charge generating layer has one or both of an electron relay layer and an electron injection buffer layer in addition to the P-type layer.

[0320] The electron relay layer contains at least a substance having electron transport properties and has the function of preventing interaction between the electron injection buffer layer and the P-type layer and smoothly transferring electrons. The LUMO level of the substance having electron transport properties contained in the electron relay layer is preferably between the LUMO level of the acceptor substance in the P-type layer and the LUMO level of the substance contained in the layer of the electron transport layer that is in contact with the charge generation layer. The specific energy level of the LUMO level of the substance having electron transport properties used in the electron relay layer is -5.0 eV or more, preferably -5.0 eV or more and -3.0 eV or less. Note that the substance having electron transport properties used in the electron relay layer is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0321] The electron injection buffer layer can be made of a material with high electron injection properties, such as alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)).

[0322] In addition, when the electron-injection buffer layer is formed to contain a substance having electron-transporting properties and a donor substance, examples of the donor substance include alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), and rare earth metal compounds (including oxides, halides, and carbonates)), as well as organic compounds such as tetrathianaphthacene (abbreviation: TTN), nickelocene, and decamethylnickelocene. Note that the substance having electron-transporting properties can be formed using the same material as the material constituting the electron-transporting layer 114 described above.

[0323] Although Fig. 34 illustrates an organic EL device having two light-emitting units, the present invention can be applied to an organic EL device having three or more stacked light-emitting units. By arranging multiple light-emitting units between a pair of electrodes and separating them with a charge-generating layer, as in the light-emitting device according to this embodiment, it is possible to realize a device that can emit high-luminance light while maintaining a low current density and that has a long life. Furthermore, it is possible to realize a light-emitting device that can be driven at a low voltage and consumes low power.

[0324] Furthermore, by making the emission colors of the respective light-emitting units different, it is possible to obtain light emission of a desired color from the entire organic EL device. For example, in an organic EL device having two light-emitting units, it is possible to obtain an organic EL device that emits white light from the entire organic EL device by obtaining red and green emission colors from light-emitting unit A and blue emission color from light-emitting unit B. Furthermore, by obtaining emission of the same color from light-emitting unit A and light-emitting unit B, high-luminance emission is possible while maintaining a low current density, and a long-life element can be realized.

[0325] The cathode 102 can be formed from a metal, alloy, electrically conductive compound, or mixture thereof having a low work function (specifically, 3.8 eV or less). Specific examples of such cathode materials include alkali metals such as lithium (Li) and cesium (Cs), elements belonging to Group 1 or Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), alloys containing these (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these. However, by providing an electron injection layer between the cathode 102 and the electron transport layer, various conductive materials such as Al, Ag, ITO, and indium oxide-tin oxide containing silicon or silicon oxide can be used as the cathode 102, regardless of the magnitude of the work function.

[0326] These conductive materials can be formed into films by dry methods such as vacuum deposition and sputtering, ink jet methods, spin coating methods, etc. Alternatively, they may be formed by wet methods using a sol-gel method, or by wet methods using a paste of a metal material.

[0327] The EL layer 103 may be formed by any of various methods, including dry and wet methods, such as vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, and spin coating.

[0328] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0329] The configuration of the layer provided between the anode 101 and the cathode 102 is not limited to the above. However, a configuration in which a light-emitting region where holes and electrons recombine is provided at a location away from the anode 101 and the cathode 102 is preferred, so that quenching caused by the proximity of the light-emitting region to the metals used in the electrodes and the carrier injection layer is suppressed.

[0330] Furthermore, a hole transport layer or an electron transport layer in contact with the light-emitting layer 113, particularly a carrier transport layer close to the recombination region in the light-emitting layer 113, is preferably made of a material having a band gap larger than that of the light-emitting material constituting the light-emitting layer or the light-emitting material contained in the light-emitting layer, in order to suppress energy transfer from excitons generated in the light-emitting layer.

[0269] This embodiment can be freely combined with other embodiment modes.

[0331] Embodiment 2 In this embodiment, a structural example of a display device according to one embodiment of the present invention will be described.

[0332] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, smartphones, wristwatch-type terminals, tablet terminals, personal digital assistants, and sound reproducing devices.

[0333] [Display Device 400A] FIG. 8 shows a perspective view of the display device 400A, and FIG. 9A shows a cross-sectional view of the display device 400A.

[0334] The display device 400A has a configuration in which a substrate 452 and a substrate 451 are bonded together. In Fig. 9, the substrate 452 is clearly indicated by a dashed line.

[0335] The display device 400A includes a display portion 462, a circuit 464, wiring 465, and the like. Fig. 9 shows an example in which an IC 473 and an FPC 472 are mounted on the display device 400A. Therefore, the configuration shown in Fig. 9 can also be considered as a display module including the display device 400A, an IC (integrated circuit), and an FPC.

[0336] The circuit 464 can be, for example, a scanning line driver circuit.

[0337] The wiring 465 has a function of supplying signals and power to the display portion 462 and the circuit 464. The signals and power are input to the wiring 465 from the outside via the FPC 472 or input to the wiring 465 from the IC 473.

[0338] 9 shows an example in which an IC 473 is provided on a substrate 451 by a chip-on-glass (COG) method, a chip-on-film (COF) method, or the like. The IC 473 can be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. The display device 400A and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by a COF method or the like.

[0339] FIG. 9A shows an example of a cross section of the display device 400A, in which a part of a region including an FPC 472, a part of a circuit 464, a part of a display portion 462, and a part of a region including an end portion are cut away.

[0340] The display device 400A shown in Figure 9A has a transistor 201, a transistor 205, a light-emitting device 430a that emits red light, a light-emitting device 430b that emits green light, and a light-emitting device 430c that emits blue light, etc., between a substrate 451 and a substrate 452.

[0341] The light-emitting device described as an example in Embodiment 1 can be applied to the light-emitting device 430a, the light-emitting device 430b, and the light-emitting device 430c.

[0342] Here, when a pixel of a display device has three types of subpixels having light-emitting devices that emit different colors, the three subpixels include subpixels of three colors of R, G, and B, or subpixels of three colors of yellow (Y), cyan (C), and magenta (M), etc. When a pixel of a display device has four subpixels, the four subpixels include subpixels of four colors of R, G, B, and white (W), or subpixels of four colors of R, G, B, and Y, etc.

[0343] The protective layer 416 and the substrate 452 are bonded via an adhesive layer 442. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting device. In FIG. 9A , a space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 is filled with an inert gas (such as nitrogen or argon), and a hollow sealing structure is applied. The adhesive layer 442 may be provided so as to overlap the light-emitting device. Furthermore, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from the adhesive layer 442.

[0344] The light-emitting devices 430a, 430b, and 430c each have an optical adjustment layer between a pixel electrode and an EL layer. The light-emitting device 430a has an optical adjustment layer 426a, the light-emitting device 430b has an optical adjustment layer 426b, and the light-emitting device 430c has an optical adjustment layer 426c. For details of the light-emitting devices, refer to Embodiment 1.

[0345] The pixel electrodes 411 a , 411 b , and 411 c are connected to the conductive layer 222 b of the transistor 205 through openings provided in the insulating layer 214 .

[0346] The pixel electrodes and the edges of the optical adjustment layer are covered with an insulating layer 421. The pixel electrodes contain a material that reflects visible light, and the counter electrode contains a material that transmits visible light.

[0347] Light emitted from the light-emitting device is emitted toward the substrate 452. The substrate 452 is preferably made of a material that is highly transparent to visible light.

[0348] The transistor 201 and the transistor 205 are both formed over a substrate 451. These transistors can be manufactured using the same material and through the same process.

[0349] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 451 in this order. A part of the insulating layer 211 functions as a gate insulating layer of each transistor. A part of the insulating layer 213 functions as a gate insulating layer of 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.

[0350] At least one insulating layer covering the transistor is preferably made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. With this structure, it is possible to effectively prevent impurities from diffusing into the transistor from the outside, thereby improving the reliability of the display device.

[0351] It is preferable to use an inorganic insulating film for each of the insulating layers 211, 213, and 215. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film may also be used. Two or more of the above insulating films may be stacked.

[0352] Here, organic insulating films often have lower barrier properties than inorganic insulating films. Therefore, it is preferable that the organic insulating film has an opening near the edge of the display device 400A. This makes it possible to prevent impurities from entering from the edge of the display device 400A through the organic insulating film. Alternatively, the organic insulating film may be formed so that the edge of the organic insulating film is located inside the edge of the display device 400A, so that the organic insulating film is not exposed at the edge of the display device 400A.

[0353] An organic insulating film is suitable for the insulating layer 214 that 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.

[0354] 9A , an opening is formed in insulating layer 214. This makes it possible to prevent impurities from entering display unit 462 from the outside through insulating layer 214, even when an organic insulating film is used for insulating layer 214. This makes it possible to improve the reliability of display device 400A.

[0355] The transistor 201 and the transistor 205 each include a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as a source and a drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0356] 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.

[0357] The transistor 201 and the transistor 205 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0358] The crystallinity of a semiconductor material used for a 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 transistor characteristics.

[0359] The semiconductor layer of the transistor preferably contains metal oxide (also referred to as an oxide semiconductor). That is, the display device of this embodiment preferably uses a transistor in which a channel formation region is formed using metal oxide (hereinafter referred to as an OS transistor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon and single-crystal silicon).

[0360] 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.

[0361] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) as the semiconductor layer.

[0362] 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 a composition in which In:M:Zn=1:1:1 or thereabouts, a composition in which In:M:Zn=1:1:1.2 or thereabouts, a composition in which In:M:Zn=2:1:3 or thereabouts, a composition in which In:M:Zn=3:1:2 or thereabouts, a composition in which In:M:Zn=4:2:3 or thereabouts, a composition in which In:M:Zn=4:2:4.1 or thereabouts, a composition in which In:M:Zn=5:1:3 or thereabouts, a composition in which In:M:Zn=5:1:6 or thereabouts, a composition in which In:M:Zn=5:1:7 or thereabouts, a composition in which In:M:Zn=5:1:8 or thereabouts, a composition in which In:M:Zn=6:1:6 or thereabouts, and a composition in which In:M:Zn=5:2:5 or thereabouts. The term "nearby composition" includes a range of ±30% of the desired atomic ratio.

[0363] For example, when describing a composition having 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 or more and 3 or less, and the atomic ratio of Zn is 2 or more and 4 or less. Furthermore, when describing a composition having 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 more than 0.1 and 2 or less, and the atomic ratio of Zn is 5 or more and 7 or less. Furthermore, when describing a composition having 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 more than 0.1 and 2 or less, and the atomic ratio of Zn is more than 0.1 and 2 or less.

[0364] The transistors included in the circuit 464 may have the same structure as or different from the transistors included in the display portion 462. The transistors included in the circuit 464 may all have the same structure or may have two or more types of structures. Similarly, the transistors included in the display portion 462 may all have the same structure or may have two or more types of structures.

[0365] A connection portion 204 is provided in a region of the substrate 451 where the substrate 452 does not overlap. In the connection portion 204, a wiring 465 is electrically connected to an FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 has an example of a stacked structure of a conductive film obtained by processing the same conductive film as the pixel electrode and a conductive film obtained by processing the same conductive film as the optical adjustment layer. The conductive layer 466 is exposed on the top surface of the connection portion 204. This allows the connection portion 204 and the FPC 472 to be electrically connected via the connection layer 242.

[0366] It is preferable to provide a light-shielding layer 417 on the surface of substrate 452 facing substrate 451. In addition, various optical members can be arranged on the outside of substrate 452. Examples of optical members include a polarizing plate, a retardation plate, a light diffusion layer (such as a diffusion film), an anti-reflection layer, and a light-collecting film. In addition, an antistatic film that suppresses the adhesion of dust, a water-repellent film that makes it difficult for dirt to adhere, a hard coat film that suppresses the occurrence of scratches during use, an impact absorbing layer, etc. may be arranged on the outside of substrate 452.

[0367] By providing the protective layer 416 that covers the light-emitting device, impurities such as water can be prevented from entering the light-emitting device, and the reliability of the light-emitting device can be improved.

[0368] In a region 228 near the edge of the display device 400A, it is preferable that the insulating layer 215 and the protective layer 416 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 416 contact each other. This makes it possible to prevent impurities from entering the display unit 462 from the outside via the organic insulating film. Therefore, it is possible to improve the reliability of the display device 400A.

[0369] 9B shows an example of a three-layer structure of the protective layer 416. In FIG. 9B, the protective layer 416 has an inorganic insulating layer 416a on the light-emitting device 430c, an organic insulating layer 416b on the inorganic insulating layer 416a, and an inorganic insulating layer 416c on the organic insulating layer 416b.

[0370] The ends of inorganic insulating layer 416a and inorganic insulating layer 416c extend outward beyond the ends of organic insulating layer 416b and are in contact with each other. Inorganic insulating layer 416a is in contact with insulating layer 215 (inorganic insulating layer) through an opening in insulating layer 214 (organic insulating layer). This allows the insulating layer 215 and protective layer 416 to surround the light-emitting device, thereby improving the reliability of the light-emitting device.

[0371] In this way, the protective layer 416 may have a laminated structure of an organic insulating film and an inorganic insulating film. In this case, it is preferable that the end of the inorganic insulating film extends further outward than the end of the organic insulating film.

[0372] The substrate 451 and the substrate 452 can each be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like. A material that transmits light is used for the substrate on the side from which light from the light-emitting device is extracted. Using a flexible material for the substrate 451 and the substrate 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used for the substrate 451 or the substrate 452.

[0373] The substrates 451 and 452 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 the substrates 451 and 452 may be made of glass having a thickness sufficient to provide flexibility.

[0374] When a circularly polarizing plate is superimposed on a display device, it is preferable that the display device has a substrate with high optical isotropy. A substrate with high optical isotropy has small birefringence (or a small amount of birefringence).

[0375] The absolute value of the retardation (phase difference) of a substrate having high optical isotropy is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0376] Examples of films with high optical isotropy include triacetyl cellulose (TAC, also known as cellulose triacetate) films, cycloolefin polymer (COP) films, cycloolefin copolymer (COC) films, and acrylic films.

[0377] Furthermore, when a film is used as a substrate, the film may absorb water, causing deformation such as wrinkles in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferably 0.1% or less, and even more preferably 0.01% or less.

[0378] The adhesive layer can be made of various curable adhesives, such as photocurable 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.

[0379] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0380] 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.

[0381] Examples of light-transmitting conductive materials include conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene. Alternatively, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metal materials, can be used. Alternatively, nitrides of such metal materials (e.g., titanium nitride) can be used. When using metal materials or alloy materials (or their nitrides), it is preferable to thin them sufficiently to ensure light-transmitting properties. A stacked film of the above materials can also be used as the conductive layer. For example, a stacked film of an alloy of silver and magnesium and indium tin oxide is preferable because it can enhance conductivity. These materials can also be used for conductive layers such as various wirings and electrodes constituting display devices, and conductive layers (conductive layers functioning as pixel electrodes or common electrodes) in light-emitting devices.

[0382] 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.

[0383] [Display Device 400B] Fig. 10A shows a cross-sectional view of the display device 400B. The perspective view of the display device 400B is similar to that of the display device 400A (Fig. 8). Fig. 10A shows an example of a cross-section of the display device 400B, where a portion of a region including the FPC 472, a portion of the circuit 464, and a portion of the display unit 462 are cut away. Fig. 10A shows an example of a cross-section of the display unit 462, particularly, where a region including the light-emitting device 430b that emits green light and the light-emitting device 430c that emits blue light is cut away. Note that descriptions of portions similar to those of the display device 400A may be omitted.

[0384] A display device 400B shown in FIG. 10A includes the transistor 202, the transistor 210, the light-emitting device 430b, the light-emitting device 430c, and the like between a substrate 453 and a substrate 454.

[0385] The substrate 454 and the protective layer 416 are bonded together via an adhesive layer 442. The adhesive layer 442 is provided to overlap the light-emitting device 430b and the light-emitting device 430c, respectively, and a solid sealing structure is applied to the display device 400B.

[0386] The substrate 453 and the insulating layer 212 are bonded together by an adhesive layer 455 .

[0387] The display device 400B is manufactured by first bonding a fabrication substrate provided with the insulating layer 212, the transistors, the light-emitting devices, and the like to a substrate 454 provided with a light-shielding layer 417 with an adhesive layer 442. The fabrication substrate is then peeled off, and a substrate 453 is attached to the exposed surface, thereby transferring each component formed on the fabrication substrate to the substrate 453. The substrate 453 and the substrate 454 are preferably flexible. This can increase the flexibility of the display device 400B.

[0388] The insulating layer 212 can be formed using the inorganic insulating film that can be used for the insulating layer 211, the insulating layer 213, and the insulating layer 215, respectively.

[0389] The pixel electrode is connected to a conductive layer 222b of the transistor 210 through an opening provided in the insulating layer 214. The conductive layer 222b is connected to a low-resistance region 231n through openings provided in the insulating layer 215 and the insulating layer 225. The transistor 210 has a function of controlling driving of the light-emitting device.

[0390] The ends of the pixel electrodes are covered with an insulating layer 421 .

[0391] Light emitted from the light-emitting devices 430b and 430c is emitted toward the substrate 454. The substrate 454 is preferably made of a material that is highly transparent to visible light.

[0392] A connection portion 204 is provided in a region of the substrate 453 where the substrate 454 does not overlap. In the connection portion 204, a wiring 465 is electrically connected to an FPC 472 via a conductive layer 466 and a connection layer 242. The conductive layer 466 can be obtained by processing the same conductive film as the pixel electrode. This allows the connection portion 204 and the FPC 472 to be electrically connected via the connection layer 242.

[0393] The transistor 202 and the transistor 210 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a semiconductor layer including a channel formation region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 functioning as a gate insulating layer, a conductive layer 223 functioning as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel formation region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel formation region 231i.

[0394] The conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n through an opening provided in the insulating layer 215. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

[0395] 10A shows an example in which the top surface and side surfaces of the semiconductor layer are covered with an insulating layer 225. 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.

[0396] 10B , 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 insulating layer 225 is processed using the conductive layer 223 as a mask, thereby manufacturing the structure shown in FIG. 10B . In FIG. 10B , 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 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.

[0397] 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.

[0398] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0399] Embodiment Mode 3 In this embodiment mode, a structural example of a display device different from the above will be described.

[0400] The display device of the present embodiment can be a high-definition display device, and therefore can be used as a display unit of a wearable device that can be worn on the head, such as a wristwatch-type or bracelet-type information terminal (wearable device), a head-mounted display or other VR device, or a glasses-type AR device.

[0401] 11A shows a perspective view of the display module 280. The display module 280 has a display device 400C and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 400C, and may be a display device 400D or a display device 400E, which will be described later.

[0402] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display portion 281. The display portion 281 is a region that displays an image in the display module 280, and is a region where light from each pixel provided in a pixel portion 284 (described later) can be viewed.

[0403] 11B is a perspective view schematically showing the configuration on the substrate 291 side. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked on the substrate 291. A terminal portion 285 for connecting to the FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 composed of a plurality of wirings.

[0404] The pixel section 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of FIG. 11B. The pixel 284a has light-emitting devices 430a, 430b, and 430c that emit light of different colors. The plurality of light-emitting devices may be arranged in a stripe array as shown in FIG. 11B. The stripe array allows pixel circuits to be arranged at high density, thereby providing a high-resolution display device. Various array methods, such as a delta array and a pentile array, can also be applied.

[0405] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0406] One pixel circuit 283a is a circuit that controls the light emission of three light-emitting devices included in one pixel 284a. One pixel circuit 283a may be configured to have three circuits that control the light emission of one light-emitting device. For example, the pixel circuit 283a may be configured to have at least one selection transistor, one current control transistor (drive transistor), and a capacitor element for each light-emitting device. In this case, a gate signal is input to the gate of the selection transistor, and a source signal is input to either the source or the drain. This realizes an active matrix display device.

[0407] The circuit portion 282 includes a circuit for driving each pixel circuit 283 a of the pixel circuit portion 283. For example, the circuit portion 282 preferably includes one or both of a gate line driver circuit and a source line driver circuit. In addition, the circuit portion 282 may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0408] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit portion 282. An IC may be mounted on the FPC 290.

[0409] The display module 280 can be configured such that one or both of the pixel circuit unit 283 and the circuit unit 282 are stacked below the pixel unit 284, thereby enabling the aperture ratio (effective display area ratio) of the display unit 281 to be extremely high. For example, the aperture ratio of the display unit 281 can be 40% or more and less than 100%, preferably 50% or more and 95% or less, and more preferably 60% or more and 95% or less. Furthermore, the pixels 284a can be arranged at an extremely high density, enabling the resolution of the display unit 281 to be extremely high. For example, it is preferable that the pixels 284a be arranged in the display unit 281 at a resolution of 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and 20,000 ppi or less, or 30,000 ppi or less.

[0410] Because such a display module 280 has extremely high resolution, it can be suitably used in VR devices such as head-mounted displays, or in glasses-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so even when the display unit is enlarged with lenses, the pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic devices with relatively small display units. For example, it can be suitably used in the display unit of a wearable electronic device such as a wristwatch.

[0411] [Display Device 400C] A display device 400C shown in FIG. 12 includes a substrate 301, light-emitting devices 430a, 430b, and 430c, a capacitor 240, and a transistor 310.

[0412] 11A and 11B. The laminated structure from substrate 301 to insulating layer 255 corresponds to substrate 100 and insulating layer 120 in the first embodiment.

[0413] The transistor 310 has a channel formation region in a substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region in which the substrate 301 is doped with impurities and functions as one of a source and a drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311 and functions as an insulating layer.

[0414] An element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0415] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided over the insulating layer 261 .

[0416] The capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located therebetween. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 245 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as a dielectric of the capacitor 240.

[0417] The conductive layer 241 is provided over the insulating layer 261 and is buried in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 by a plug 271 buried in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0418] An insulating layer 255 is provided to cover the capacitor 240, and light-emitting devices 430a, 430b, 430c, etc. are provided on the insulating layer 255. A protective layer 416 is provided on the light-emitting devices 430a, 430b, 430c, and a substrate 420 is bonded to the upper surface of the protective layer 416 with a resin layer 419.

[0419] The pixel electrode of the light-emitting device is electrically connected to one of the source or drain of the transistor 310 by a plug 256 embedded in the insulating layer 255, a conductive layer 241 embedded in the insulating layer 254, and a plug 271 embedded in the insulating layer 261.

[0420] 13 is different from the display device 400C mainly in the configuration of the transistors. Note that descriptions of parts that are the same as those of the display device 400C may be omitted.

[0421] The transistor 320 is a transistor in which a metal oxide (also referred to as an oxide semiconductor) is used for a semiconductor layer in which a channel is formed.

[0422] The transistor 320 includes a semiconductor layer 321 , an insulating layer 323 , a conductive layer 324 , a pair of conductive layers 325 , an insulating layer 326 , and a conductive layer 327 .

[0423] 11A and 11B. A stacked structure 401 from the substrate 331 to the insulating layer 255 corresponds to the layer including the transistor in Embodiment 1. The substrate 331 can be an insulating substrate or a semiconductor substrate.

[0424] An insulating layer 332 is provided over a substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320 and prevents oxygen from being released from the semiconductor layer 321 toward the insulating layer 332. The insulating layer 332 can be, for example, a film through which hydrogen or oxygen is less likely to diffuse than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0425] A conductive layer 327 is provided over the insulating layer 332, and an insulating layer 326 is provided to cover the conductive layer 327. The conductive layer 327 functions as a first gate electrode of the transistor 320, and part of the insulating layer 326 functions as a first gate insulating layer. An oxide insulating film such as a silicon oxide film is preferably used for at least a portion of the insulating layer 326 that is in contact with the semiconductor layer 321. The top surface of the insulating layer 326 is preferably planarized.

[0426] The semiconductor layer 321 is provided over the insulating layer 326. The semiconductor layer 321 preferably includes a metal oxide (also referred to as an oxide semiconductor) film having semiconductor properties. Materials that can be suitably used for the semiconductor layer 321 will be described in detail later.

[0427] The pair of conductive layers 325 are provided over and in contact with the semiconductor layer 321 and function as a source electrode and a drain electrode.

[0428] An insulating layer 328 is provided to cover top surfaces and side surfaces of the pair of conductive layers 325 and side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided over the insulating layer 328. The insulating layer 328 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 264 or the like to the semiconductor layer 321 and prevents oxygen from being released from the semiconductor layer 321. The insulating layer 328 can be an insulating film similar to the insulating layer 332.

[0429] Openings reaching the semiconductor layer 321 are provided in the insulating layer 328 and the insulating layer 264. Inside the openings, an insulating layer 323 and a conductive layer 324 are buried, which are in contact with side surfaces of the insulating layer 264, the insulating layer 328, and the conductive layer 325 and an upper surface of the semiconductor layer 321. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0430] The upper surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are planarized so that their heights are approximately the same, and insulating layers 329 and 265 are provided to cover them.

[0431] The insulating layer 264 and the insulating layer 265 function as interlayer insulating layers. The insulating layer 329 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the insulating layer 265 or the like to the transistor 320. The insulating layer 329 can be formed using an insulating film similar to the insulating layer 328 and the insulating layer 332.

[0432] A plug 274 electrically connected to one of the pair of conductive layers 325 is provided to be embedded in the insulating layer 265, the insulating layer 329, and the insulating layer 264. Here, the plug 274 preferably includes a conductive layer 274a covering the side surfaces of the openings of the insulating layer 265, the insulating layer 329, the insulating layer 264, and the insulating layer 328 and part of the top surface of the conductive layer 325, and a conductive layer 274b in contact with the top surface of the conductive layer 274a. In this case, the conductive layer 274a is preferably made of a conductive material through which hydrogen and oxygen do not easily diffuse.

[0433] The configuration of the display device 400D from the insulating layer 254 to the substrate 420 is the same as that of the display device 400C.

[0434] 14 has a stacked structure of a transistor 310 in which a channel is formed in a substrate 301 and a transistor 320 in which a channel is formed and a semiconductor layer containing metal oxide. Note that descriptions of parts similar to those of the display devices 400C and 400D may be omitted.

[0435] An insulating layer 261 is provided to cover the transistor 310, and a conductive layer 251 is provided over the insulating layer 261. An insulating layer 262 is provided to cover the conductive layer 251, and a conductive layer 252 is provided over the insulating layer 262. The conductive layers 251 and 252 each function as wirings. An insulating layer 263 and an insulating layer 332 are provided to cover the conductive layer 252, and the transistor 320 is provided over the insulating layer 332. An insulating layer 265 is provided to cover the transistor 320, and a capacitor 240 is provided over the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected by a plug 274.

[0436] The transistor 320 can be used as a transistor that forms a pixel circuit. The transistor 310 can be used as a transistor that forms a pixel circuit or a driver circuit (gate line driver circuit, source line driver circuit) that drives the pixel circuit. The transistors 310 and 320 can be used as transistors that form various circuits such as an arithmetic circuit or a memory circuit.

[0437] By using this configuration, not only pixel circuits but also driving circuits etc. can be formed directly below the light-emitting device, making it possible to make the display device smaller than when driving circuits are provided around the periphery of the display area.

[0438] 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.

[0439] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0440] Embodiment Mode 5 In this embodiment mode, a high-definition display device will be described.

[0441] [Configuration Example of Pixel Circuit] Hereinafter, an example of pixels suitable for a high-definition display device and an example of a method for arranging the pixels will be described.

[0442] 15A shows an example of a circuit diagram of the pixel unit 70. The pixel unit 70 is composed of two pixels (pixel 70a and pixel 70b). The pixel unit 70 is also connected to wiring 51a, wiring 51b, wiring 52a, wiring 52b, wiring 52c, wiring 52d, wiring 53a, wiring 53b, wiring 53c, etc.

[0443] Pixel 70a has subpixels 71a, 72a, and 73a. Pixel 70b has subpixels 71b, 72b, and 73b. Subpixels 71a, 72a, and 73a have pixel circuits 41a, 42a, and 43a, respectively. Subpixels 71b, 72b, and 73b have pixel circuits 41b, 42b, and 43b, respectively.

[0444] Each sub-pixel has a pixel circuit and a display element 60. For example, the sub-pixel 71a has a pixel circuit 41a and a display element 60. Here, a case where a light-emitting device such as an organic EL element is used as the display element 60 is shown.

[0445] The wirings 51a and 51b each function as a gate line. The wirings 52a, 52b, 52c, and 52d each function as a signal line (also referred to as a data line). The wirings 53a, 53b, and 53c each supply a potential to the display element 60.

[0446] The pixel circuit 41a is electrically connected to the wirings 51a, 52a, and 53a. The pixel circuit 42a is electrically connected to the wirings 51b, 52d, and 53a. The pixel circuit 43a is electrically connected to the wirings 51a, 52b, and 53b. The pixel circuit 41b is electrically connected to the wirings 51b, 52a, and 53b. The pixel circuit 42b is electrically connected to the wirings 51a, 52c, and 53c. The pixel circuit 43b is electrically connected to the wirings 51b, 52b, and 53c.

[0447] 15, by connecting two gate lines to one pixel, the number of source lines can be halved compared to the stripe arrangement, which makes it possible to halve the number of terminals of the IC used as the source driver circuit, thereby reducing the number of parts.

[0448] Furthermore, it is preferable to configure a wiring that functions as a signal line to connect pixel circuits corresponding to the same color. For example, when a signal with an adjusted potential is supplied to the wiring to correct brightness variations between pixels, the correction value may differ significantly for each color. Therefore, by configuring all pixel circuits connected to a single signal line to be pixel circuits corresponding to the same color, correction can be made easier.

[0449] Each pixel circuit includes a transistor 61, a transistor 62, and a capacitor 63. For example, in the pixel circuit 41a, the gate of the transistor 61 is electrically connected to a wiring 51a, one of the source and the drain is electrically connected to a wiring 52a, and the other of the source and the drain is electrically connected to the gate of the transistor 62 and one electrode of the capacitor 63. The transistor 62 has one of the source and the drain electrically connected to one electrode of the display element 60, and the other of the source and the drain electrically connected to the other electrode of the capacitor 63 and the wiring 53a. The other electrode of the display element 60 is electrically connected to a wiring to which a potential V1 is applied.

[0450] As shown in Figure 15, the other pixel circuits have the same configuration as the pixel circuit 41a, except that the wiring to which the gate of the transistor 61 is connected, the wiring to which one of the source or drain of the transistor 61 is connected, and the wiring to which the other electrode of the capacitor 63 is connected are different.

[0451] 15 , the transistor 61 functions as a selection transistor. The transistor 62 is connected in series to the display element 60 and has a function of controlling a current flowing through the display element 60. The capacitor 63 has a function of holding the potential of a node to which the gate of the transistor 62 is connected. Note that if the leakage current when the transistor 61 is off or the leakage current through the gate of the transistor 62 is extremely small, the capacitor 63 does not necessarily have to be provided.

[0452] 15, the transistor 62 preferably has a first gate and a second gate that are electrically connected to each other. By having two gates, the current that can flow through the transistor 62 can be increased. This is particularly preferable for high-resolution display devices, because the current can be increased without increasing the size of the transistor 62, particularly its channel width.

[0453] Note that the transistor 62 may have one gate. This structure eliminates the need for a step of forming a second gate, simplifying the process compared to the above. The transistor 61 may have two gates. This structure allows the size of each transistor to be reduced. Furthermore, the first gate and the second gate of each transistor may be electrically connected to each other. Alternatively, one of the gates may be electrically connected to a different wiring. In this case, the threshold voltage of the transistor can be controlled by varying the potential applied to the wiring.

[0454] Of the pair of electrodes of the display element 60, the electrode electrically connected to the transistor 62 corresponds to a pixel electrode. Here, FIG. 5 shows a configuration in which the electrode electrically connected to the transistor 62 of the display element 60 serves as a cathode, and the opposite electrode serves as an anode. This configuration is particularly effective when the transistor 62 is an n-channel transistor. That is, when the transistor 62 is on, the potential applied by the wiring 53a becomes the source potential, so that the current flowing through the transistor 62 can be kept constant regardless of variations or fluctuations in the resistance of the display element 60. Furthermore, a p-channel transistor may be used as the transistor included in the pixel circuit.

[0455] Embodiment 6 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.

[0456] 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.

[0457] The metal oxide can be formed by a sputtering method, a chemical vapor deposition (CVD) method such as a metal organic chemical vapor deposition (MOCVD) method, or an atomic layer deposition (ALD) method.

[0458] <Classification of Crystal Structure> Examples of the crystal structure of an oxide semiconductor include amorphous (including completely amorphous), c-axis-aligned crystalline line (CAAC), nanocrystalline line (nc), cloud-aligned composite (CAC), single crystal, and polycrystalline.

[0459] The crystalline structure of the film or substrate can be evaluated using an X-ray diffraction (XRD) spectrum. For example, it can be evaluated using an XRD spectrum obtained by a GIXD (Grazing-Incident XRD) measurement. The GIXD method is also called the thin film method or the Seemann-Bohlin method.

[0460] For example, in the case of a quartz glass substrate, the shape of the peak in the XRD spectrum is almost symmetrical. On the other hand, in the case of an IGZO film having a crystalline structure, the shape of the peak in the XRD spectrum is asymmetrical. The asymmetrical shape of the peak in the XRD spectrum clearly indicates the presence of crystals in the film or substrate. In other words, if the shape of the peak in the XRD spectrum is not symmetrical, the film or substrate cannot be said to be in an amorphous state.

[0461] The crystalline structure of the film or substrate can be evaluated by a diffraction pattern (also referred to as a nanobeam electron diffraction pattern) observed by nanobeam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, and it can be confirmed that the quartz glass is in an amorphous state. Furthermore, a spot-like pattern is observed in the diffraction pattern of an IGZO film formed at room temperature, rather than a halo. For this reason, it is estimated that the IGZO film formed at room temperature is neither crystalline nor amorphous, but is in an intermediate state, and it cannot be concluded that it is in an amorphous state.

[0462] <<Structure of Oxide Semiconductor>> Note that oxide semiconductors may be classified differently from the above when focusing on their structures. For example, oxide semiconductors are classified into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the above-mentioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, pseudo-amorphous-like oxide semiconductors (a-like OSs), amorphous oxide semiconductors, and the like.

[0463] Here, the above-mentioned CAAC-OS, nc-OS, and a-like OS will be described in detail.

[0464] [CAAC-OS] A CAAC-OS is an oxide semiconductor having multiple crystalline regions, each with its c-axis aligned in a specific direction. The specific direction refers to the thickness direction of the CAAC-OS film, the normal direction to the surface where the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region having periodic atomic arrangement. If the atomic arrangement is considered as a lattice arrangement, a crystalline region is also a region with a uniform lattice arrangement. Furthermore, a CAAC-OS has a region where multiple crystalline regions are connected in the a-b plane direction, and the region may have distortion. Note that distortion refers to a portion where the lattice arrangement changes between a region with a uniform lattice arrangement and a region with another uniform lattice arrangement in a region where multiple crystalline regions are connected. In other words, a CAAC-OS is an oxide semiconductor whose c-axes are aligned and whose orientation is not clearly aligned in the a-b plane direction.

[0465] Each of the multiple crystalline regions is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of a single minute crystal, the maximum diameter of the crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of the crystalline region may be several tens of nanometers.

[0466] In an In-M-Zn oxide (wherein the element M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, and the like), the CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium (In) and oxygen (hereinafter referred to as an In layer) and a layer containing the element M, zinc (Zn), and oxygen (hereinafter referred to as an (M, Zn) layer) are stacked. Note that indium and the element M are mutually substituted. Therefore, the (M, Zn) layer may contain indium. The In layer may contain the element M. The In layer may contain Zn. The layered structure is observed as a lattice image in a high-resolution transmission electron microscope (TEM) image, for example.

[0467] When a CAAC-OS film is subjected to structural analysis using an XRD apparatus, for example, a peak indicating c-axis orientation is detected at or near 2θ = 31° in out-of-plane XRD measurement using θ / 2θ scanning. Note that the position of the peak indicating c-axis orientation (the value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

[0468] For example, multiple bright spots are observed in the electron diffraction pattern of a CAAC-OS film, and the spots are observed at positions that are point-symmetric with respect to a spot of an incident electron beam that has passed through the sample (also referred to as a direct spot).

[0469] When a crystalline region is observed from the specific direction, the lattice arrangement in the crystalline region is basically a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be a non-regular hexagon. The distortion may have a pentagonal, heptagonal, or other lattice arrangement. In CAAC-OS, no clear grain boundary can be identified even near the distortion. This indicates that the distortion in the lattice arrangement suppresses the formation of grain boundaries. This is thought to be because CAAC-OS can tolerate distortion due to the lack of close-packed oxygen atom arrangement in the a-b plane direction and the change in interatomic bond distance caused by metal atom substitution.

[0470] Note that a crystal structure in which clear grain boundaries are observed is called polycrystalline. The grain boundaries act as recombination centers, and are likely to trap carriers, resulting in a decrease in the on-state current of a transistor and a decrease in field-effect mobility. Therefore, CAAC-OS, in which clear grain boundaries are not observed, is one of the crystalline oxides having a crystal structure suitable for a semiconductor layer of a transistor. Note that a structure containing Zn is preferable for forming a CAAC-OS. For example, In—Zn oxide and In—Ga—Zn oxide are suitable because they can suppress the generation of grain boundaries more effectively than In oxide.

[0471] CAAC-OS is an oxide semiconductor with high crystallinity and no clear crystal grain boundaries. Therefore, it can be said that the CAAC-OS is less susceptible to a decrease in electron mobility due to crystal grain boundaries. Furthermore, since the crystallinity of an oxide semiconductor can be reduced by the inclusion of impurities, the formation of defects, or the like, the CAAC-OS can also be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Therefore, an oxide semiconductor having a CAAC-OS has stable physical properties. Therefore, an oxide semiconductor having a CAAC-OS is heat-resistant and highly reliable. Furthermore, the CAAC-OS is stable even against high temperatures (so-called thermal budget) in the manufacturing process. Therefore, the use of a CAAC-OS in an OS transistor can increase the flexibility of the manufacturing process.

[0472] [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 microcrystals. Note that the size of the microcrystals is, for example, 1 nm to 10 nm, particularly 1 nm to 3 nm, and therefore the microcrystals are also called nanocrystals. Furthermore, the nc-OS does not exhibit regularity in the crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Therefore, depending on the analysis method, the nc-OS may be indistinguishable from an a-like OS or an amorphous oxide semiconductor. For example, when a structural analysis of an nc-OS film is performed using an XRD apparatus, no peak indicating crystallinity is detected in out-of-plane XRD measurement using θ / 2θ scanning. When an nc-OS film is subjected to electron diffraction (also referred to as selected-area electron diffraction) using an electron beam with a probe diameter larger than that of a nanocrystal (e.g., 50 nm or more), a diffraction pattern resembling a halo pattern is observed. On the other hand, when an nc-OS film is subjected to electron diffraction (also referred to as nanobeam electron diffraction) using an electron beam with a probe diameter close to or smaller than that of a nanocrystal (e.g., 1 nm to 30 nm), an electron diffraction pattern in which multiple spots are observed within a ring-shaped region centered on a direct spot may be obtained.

[0473] [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 the CAAC-OS. Furthermore, the a-like OS has a higher hydrogen concentration in the film than the nc-OS and the CAAC-OS.

[0474] <<Structure of Oxide Semiconductor>> Next, the above-described CAC-OS will be described in detail. Note that the CAC-OS relates to a material structure.

[0475] [CAC-OS] CAC-OS is, for example, a material in which elements constituting a metal oxide are unevenly distributed in a size of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or in the vicinity thereof. Note that hereinafter, a state in which one or more metal elements are unevenly distributed in a metal oxide and regions containing the metal elements are mixed in a size of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or in the vicinity thereof, is also referred to as a mosaic or patch state.

[0476] Furthermore, the CAC-OS has a mosaic structure in which a material is separated into a first region and a second region, and the first region is distributed throughout the film (hereinafter also referred to as a cloud structure). That is, the CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0477] 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.

[0478] Specifically, the first region is a region whose main component is indium oxide, indium zinc oxide, or the like. The second region is a region whose main component is gallium oxide, gallium zinc oxide, or the like. In other words, the first region can be referred to as a region whose main component is In. The second region can be referred to as a region whose main component is Ga.

[0479] It should be noted that there are cases where a clear boundary between the first region and the second region cannot be observed.

[0480] Furthermore, CAC-OS in In—Ga—Zn oxide refers to a structure in which a mosaic of regions containing Ga as the main component and regions containing In as the main component are randomly arranged in a material composition containing In, Ga, Zn, and O. Therefore, it is presumed that CAC-OS has a structure in which metal elements are distributed nonuniformly.

[0481] The CAC-OS can be formed by sputtering without heating the substrate. When the CAC-OS is formed by sputtering, one or more of an inert gas (typically argon), oxygen gas, and nitrogen gas may be used as the deposition gas. The lower the flow rate of oxygen gas relative to the total flow rate of deposition gas during deposition, the more preferable it is. For example, the flow rate of oxygen gas relative to the total flow rate of deposition gas during deposition is preferably 0% or more and less than 30%, and more preferably 0% or more and 10% or less.

[0482] Furthermore, for example, in the case of CAC-OS in an In—Ga—Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) can confirm that the CAC-OS has a structure in which a region containing In as a main component (first region) and a region containing Ga as a main component (second region) are unevenly distributed and mixed.

[0483] 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).

[0484] 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.

[0485] Therefore, when a CAC-OS is used in a transistor, the conductivity due to the first region and the insulating property due to the second region act complementarily, thereby providing the CAC-OS with a switching function (a function of turning on / off). In other words, a CAC-OS has a conductive function in a part of the material and an insulating function in a part of the material, and the entire material functions as a semiconductor. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using a CAC-OS in a transistor, a high on-current (I ｏｎ), high field-effect mobility (μ), and good switching behavior can be achieved.

[0486] Furthermore, a transistor using the CAC-OS has high reliability, and therefore, the CAC-OS is ideal for various semiconductor devices such as display devices.

[0487] Oxide semiconductors have a variety of structures, each of which has different characteristics. The oxide semiconductor of one embodiment of the present invention may include two or more of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, an a-like OS, a CAC-OS, an nc-OS, and a CAAC-OS.

[0488] <Transistor Having Oxide Semiconductor> Next, a case where the oxide semiconductor is used for a transistor will be described.

[0489] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility and high reliability can be realized.

[0490] For the transistor, an oxide semiconductor having a low carrier concentration is preferably used. For example, the carrier concentration of the oxide semiconductor is 1×10 １７ cm −３ Below 1 × 10, preferably １５ cm −３ More preferably, 1×10 １３ cm −３ or less, more preferably 1 × 10 １１ cm −３ More preferably, 1×10 １０ cm −３ is less than 1×10 −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.

[0491] 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.

[0492] 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.

[0493] 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.

[0494] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0495] When an oxide semiconductor contains silicon or carbon, which is one of Group 14 elements, defect levels are formed in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon near the interface with the oxide semiconductor (concentration obtained by secondary ion mass spectrometry (SIMS)) are set to 2×10 １８ atoms / cm ３ Below 2 × 10, preferably １７ atoms / cm ３ The following applies.

[0496] Furthermore, when an oxide semiconductor contains an alkali metal or an alkaline earth metal, defect levels are formed and carriers are generated in some cases. Therefore, a transistor using an oxide semiconductor containing an alkali metal or an alkaline earth metal is likely to have normally-on characteristics. For this reason, when the concentration of the alkali metal or the alkaline earth metal in the oxide semiconductor obtained by SIMS is 1×10 １８ atoms / cm ３ Below 2 × 10, preferably１６ atoms / cm ３ Do the following:

[0497] Furthermore, when nitrogen is contained in an oxide semiconductor, electrons serving as carriers are generated, the carrier concentration increases, and the semiconductor is likely to become n-type. As a result, a transistor using an oxide semiconductor containing nitrogen as a semiconductor tends to have normally-on characteristics. Alternatively, when nitrogen is contained in an oxide semiconductor, trap states may be formed. As a result, the electrical characteristics of the transistor may become unstable. For this reason, the nitrogen concentration in the oxide semiconductor obtained by SIMS is set to 5×10 １９ atoms / cm ３ Less than 5×10 １８ atoms / cm ３ or less, more preferably 1 × 10 １８ atoms / cm ３ or less, more preferably 5 × 10 １７ atoms / cm ３ Do the following:

[0498] Furthermore, hydrogen contained in an oxide semiconductor may react with oxygen bonded to a metal atom to form water, which may form an oxygen vacancy. Hydrogen entering the oxygen vacancy may generate electrons as carriers. Furthermore, some of the hydrogen may bond with oxygen bonded to a metal atom to generate electrons as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen is likely to have normally-on characteristics. Therefore, it is preferable to reduce hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in the oxide semiconductor measured by SIMS is 1×10 ２０ atoms / cm ３ less than 1×10 １９ atoms / cm ３ less than 5×10 １８ atoms / cm ３ less than 1×10 １８ atoms / cm ３ Make it less than.

[0499] When an oxide semiconductor with sufficiently reduced impurities is used for a channel formation region of a transistor, stable electrical characteristics can be obtained.

[0500] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0501] Embodiment 7 In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS.

[0502] The electronic devices of this embodiment include the display device of one embodiment of the present invention. The display device of one embodiment of the present invention can easily achieve high definition, high resolution, and a large size. Therefore, the display device of one embodiment of the present invention can be used as a display portion of various electronic devices.

[0503] Furthermore, the display device of one embodiment of the present invention can be manufactured at low cost, which leads to a reduction in the manufacturing cost of electronic devices.

[0504] 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.

[0505] In particular, the display device of one embodiment of the present invention can be suitably used in electronic devices having a relatively small display area because it can increase the resolution. Examples of such electronic devices include information terminals (wearable devices) such as wristwatches and bracelets, as well as wearable devices that can be worn on the head, such as VR devices such as head-mounted displays and AR glasses-type devices. Further, examples of wearable devices include SR devices and MR devices.

[0506] The display device of one embodiment of the present invention preferably has an extremely high resolution such as HD (1280 × 720 pixels), FHD (1920 × 1080 pixels), WQHD (2560 × 1440 pixels), WQXGA (2560 × 1600 pixels), 4K2K (3840 × 2160 pixels), or 8K4K (7680 × 4320 pixels). A resolution of 4K2K, 8K4K, or higher is particularly preferable. Furthermore, the pixel density (resolution) of the display device of one embodiment of the present invention is preferably 300 ppi or higher, more preferably 500 ppi or higher, more preferably 1000 ppi or higher, more preferably 2000 ppi or higher, more preferably 3000 ppi or higher, more preferably 5000 ppi or higher, and even more preferably 7000 ppi or higher. By using a display device with such high resolution or high definition, it is possible to further enhance the sense of presence and depth in electronic devices for personal use such as portable or home use.

[0507] The electronic device of this embodiment can be incorporated along the curved surface of the inner or outer wall of a house or building, or the interior or exterior of an automobile.

[0508] The electronic device of this embodiment may have an antenna. By receiving a signal through the antenna, images, information, and the like can be displayed on a display portion. In addition, when the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0509] The electronic device of this embodiment may have a sensor (including the function of detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0510] 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.

[0511] The electronic device 6500 shown in FIG. 16A is a portable information terminal that can be used as a smartphone.

[0512] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, and the like. The display portion 6502 has a touch panel function.

[0513] The display device of one embodiment of the present invention can be applied to the display portion 6502 .

[0514] FIG. 16B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0515] 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.

[0516] 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).

[0517] In a region outside the display portion 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0518] The flexible display (flexible display device) of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. Furthermore, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0519] 17A shows an example of a television set. A television set 7100 has a display portion 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0520] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0521] 17A can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, the display portion 7000 may be provided with a touch sensor, and the television set 7100 may be operated by touching the display portion 7000 with a finger or the like. The remote control 7111 may have a display portion that displays information output from the remote control 7111. Using operation keys or a touch panel provided on the remote control 7111, the channel and volume can be controlled, and an image displayed on the display portion 7000 can be controlled.

[0522] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. Furthermore, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from a sender to a receiver) or two-way (between a sender and a receiver, or between receivers, etc.) information communication.

[0523] 17B shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. The housing 7211 includes a display portion 7000.

[0524] The display device of one embodiment of the present invention can be applied to the display portion 7000 .

[0525] 17C and 17D show an example of digital signage.

[0526] 17C includes a housing 7301, a display portion 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0527] 17D 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.

[0528] 17C and 17D, the display device of one embodiment of the present invention can be applied to the display portion 7000.

[0529] 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.

[0530] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000 but also allows the user to intuitively operate it. Furthermore, when used to provide information such as route information or traffic information, the intuitive operation can improve usability.

[0531] 17C and 17D , the digital signage 7300 or the digital signage 7400 is preferably capable of wirelessly linking with an information terminal 7311 or an information terminal 7411 such as a smartphone carried by a user. For example, advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or the information terminal 7411. By operating the information terminal 7311 or the information terminal 7411, the display on the display unit 7000 can be switched.

[0532] Furthermore, the digital signage 7300 or the digital signage 7400 can be made to run a game using the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller), thereby allowing an unspecified number of users to simultaneously participate in and enjoy the game.

[0533] FIG. 18A is a diagram showing the appearance of the camera 8000 with the viewfinder 8100 attached.

[0534] The camera 8000 includes a housing 8001, a display unit 8002, operation buttons 8003, a shutter button 8004, and the like. A detachable lens 8006 is attached to the camera 8000. Note that the lens 8006 and the housing of the camera 8000 may be integrated together.

[0535] The camera 8000 can capture an image by pressing a shutter button 8004 or touching a display portion 8002 that functions as a touch panel.

[0536] The housing 8001 has a mount with electrodes, and can be connected to a finder 8100 as well as a strobe device and the like.

[0537] The finder 8100 includes a housing 8101, a display portion 8102, a button 8103, and the like.

[0538] The housing 8101 is attached to the camera 8000 by a mount that engages with the mount of the camera 8000. The viewfinder 8100 can display an image received from the camera 8000 on a display portion 8102.

[0539] The button 8103 has a function as a power button or the like.

[0540] The display device of one embodiment of the present invention can be applied to a display portion 8002 of a camera 8000 and a display portion 8102 of a finder 8100. Note that the camera 8000 may have a built-in finder.

[0541] FIG. 18B is a diagram showing the appearance of the head-mounted display 8200.

[0542] The head-mounted display 8200 includes a mounting portion 8201, a lens 8202, a main body 8203, a display portion 8204, and a cable 8205. The mounting portion 8201 has a built-in battery 8206.

[0543] A cable 8205 supplies power from a battery 8206 to the main body 8203. The main body 8203 includes a wireless receiver or the like and can display received video information on a display portion 8204. The main body 8203 also includes a camera and can use information on the movement of the user's eyeballs or eyelids as an input means.

[0544] The wearing unit 8201 may have a plurality of electrodes at positions that come into contact with the user, capable of detecting a current that flows in accordance with the movement of the user's eyeballs, and may have a function of recognizing the line of sight. The wearing unit 8201 may also have a function of monitoring the user's pulse based on the current that flows through the electrodes. The wearing unit 8201 may also have various sensors such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may have a function of displaying biometric information of the user on the display unit 8204 and a function of changing an image displayed on the display unit 8204 in accordance with the movement of the user's head.

[0545] The display device of one embodiment of the present invention can be applied to the display portion 8204 .

[0546] 18C to 18E are diagrams showing the appearance of a head mounted display 8300. The head mounted display 8300 includes a housing 8301, a display portion 8302, a band-shaped fixture 8304, and a pair of lenses 8305.

[0547] A user can view the display on the display portion 8302 through the lens 8305. Note that it is preferable to curve the display portion 8302 because the user can feel a high sense of presence. In addition, by viewing different images displayed in different regions of the display portion 8302 through the lens 8305, three-dimensional display using parallax can be performed. Note that the present invention is not limited to a configuration in which one display portion 8302 is provided, and two display portions 8302 may be provided, with one display portion provided for each eye of the user.

[0548] The display device of one embodiment of the present invention can be applied to the display portion 8302. The display device of one embodiment of the present invention can also achieve extremely high definition. For example, even when the display is enlarged and viewed using the lens 8305 as shown in FIG. 18E , the pixels are difficult for the user to view. That is, the display portion 8302 can be used to allow the user to view a highly realistic image.

[0549] 18F is a diagram showing the appearance of a goggle-type head-mounted display 8400. The head-mounted display 8400 includes a pair of housings 8401, an attachment portion 8402, and a buffer member 8403. A display portion 8404 and a lens 8405 are provided in each of the pair of housings 8401. By displaying different images on the pair of display portions 8404, three-dimensional display using parallax can be performed.

[0550] A user can view the display portion 8404 through the lens 8405. The lens 8405 has a focus adjustment mechanism, and its position can be adjusted according to the user's eyesight. The display portion 8404 is preferably a square or a horizontally long rectangle. This can enhance the sense of realism.

[0551] The attachment portion 8402 preferably has plasticity and elasticity so that it can be adjusted according to the size of the user's face and does not slip off. Furthermore, a portion of the attachment portion 8402 preferably has a vibration mechanism that functions as a bone conduction earphone. This allows the user to enjoy video and audio simply by wearing the device, without the need for separate audio equipment such as earphones or speakers. The housing 8401 may also have a function for outputting audio data via wireless communication.

[0552] The mounting portion 8402 and the buffer member 8403 are portions that come into contact with the user's face (forehead, cheeks, etc.). The close contact of the buffer member 8403 with the user's face can prevent light leakage and enhance the sense of immersion. The buffer member 8403 is preferably made of a soft material so that it can be in close contact with the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, urethane, and sponge can be used. Furthermore, using a sponge or the like with its surface covered with cloth, leather (natural leather or synthetic leather), or the like can prevent gaps from forming between the user's face and the buffer member 8403, thereby effectively preventing light leakage. Furthermore, using such a material is preferable because it feels pleasant to the touch and prevents the user from feeling cold when worn in cold seasons. It is preferable that the buffer member 8403 or the mounting portion 8402, or other components that come into contact with the user's skin, are removable for easy cleaning or replacement.

[0553] The electronic device shown in Figures 19A to 19F 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 a function to sense, detect, or measure 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.

[0554] The electronic devices shown in Figures 19A to 19F have various functions. For example, they may have a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, or time, a function to control processing using various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. Note that the functions of the electronic devices are not limited to these, and they may have various other functions. The electronic devices may have multiple display units. Furthermore, the electronic devices may have a function to include a camera or the like to capture still images or videos and store them on a recording medium (external or built-in to the camera), a function to display the captured images on a display unit, etc.

[0555] The display device of one embodiment of the present invention can be applied to the display portion 9001 .

[0556] The electronic device shown in FIGS. 19A to 19F will be described in detail below.

[0557] FIG. 19A is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 can be used as, for example, a smartphone. Note that the mobile information terminal 9101 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, and the like. The mobile information terminal 9101 can display text and image information on multiple surfaces. FIG. 19A shows an example in which three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notifications of incoming emails, SNS messages, phone calls, etc., the title of the email or SNS message, the sender's name, the date and time, the remaining battery level, and the strength of antenna reception. Alternatively, an icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0558] 19B is a perspective view showing the mobile information terminal 9102. The mobile information terminal 9102 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9102 while storing the mobile information terminal 9102 in a breast pocket of clothes. The user can check the display without taking the mobile information terminal 9102 out of the pocket and decide, for example, whether to answer a call.

[0559] FIG. 19C is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. The mobile information terminal 9200 can also perform hands-free communication by intercommunicating with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and charging with another information terminal through a connection terminal 9006. Charging may be performed by wireless power supply.

[0560] 19D to 19F are perspective views showing a foldable mobile information terminal 9201. Also, FIG. 19D is a perspective view of the mobile information terminal 9201 in an unfolded state, FIG. 19F is a perspective view of the mobile information terminal 9201 in a folded state, and FIG. 19E is a perspective view of a state in the process of changing from one of FIGS. 19D and 19F to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent visibility of the display. The display portion 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display portion 9001 can be bent with a curvature radius of 0.1 mm or more and 150 mm or less.

[0561] 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.

[0562] This embodiment mode can be implemented by appropriately combining at least a part thereof with other embodiment modes described in this specification.

[0563] In this example, films of different materials and structures (laminated films, mixed films, etc.) were fabricated on glass substrates, and the results of heat resistance tests performed on the resulting samples (films) are shown. Nine types of samples were fabricated by varying the combination of multiple heteroaromatic compounds and film structures. The structure of each sample, along with the results, is shown in Table 1 below. The chemical formulas of the materials used in this example are shown below.

[0564]

[0565] The method for producing each sample (Sample 1 to Sample 9) is described below.

[0566] First, a sample layer was formed on a glass substrate using a vacuum deposition apparatus, and then cut into a 1 cm × 3 cm strip. Next, the substrate was placed in a bell jar heater (Shibata Chemical Co., Ltd., Bell Jar Vacuum Oven BV-001), the pressure was reduced to approximately 10 hPa, and the substrate was baked at a set temperature between 80°C and 150°C for 1 hour.

[0567] Sample 1 is a single layer film using one type of heteroaromatic compound, and was formed by vapor-depositing 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) on a glass substrate to a thickness of 10 nm.

[0568] Sample 2 is a single layer film using one type of heteroaromatic compound, and was formed by evaporating 2-[4′-(9-phenyl-9H-carbazol-3-yl)-3,1′-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq) onto a glass substrate to a thickness of 10 nm.

[0569] Sample 3 is a mixed film using multiple heteroaromatic compounds, and is prepared by depositing 2mpPCBPDBq, N-(1,1′-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), and tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(tBuppm)) on a glass substrate. ３ ) and a weight ratio of 0.8:0.2:0.06 (=2mpPCBPDBq:PCBBiF:Ir(tBuppm) ３ ) was co-evaporated to form a 40 nm thick film.

[0570] Sample 4 is a laminated film using a plurality of heteroaromatic compounds, and was formed by depositing 2mpPCBPDBq to a thickness of 10 nm on a glass substrate, and then depositing NBPhen to a thickness of 10 nm.

[0571] Sample 5 is a mixed film using multiple heteroaromatic compounds, and is composed of 2mpPCBPDBq, PCBBiF, and Ir(tBuppm) on a glass substrate. ３ and a weight ratio of 0.8:0.2:0.06 (=2mpPCBPDBq:PCBBiF:Ir(tBuppm) ３ After co-evaporating a film of 40 nm so as to form a film of 2mpPCBPDBq, a film of 10 nm was evaporated, and then a film of NBPhen was evaporated to form a film of 10 nm.

[0572] Sample 6 is a single layer film using one type of heteroaromatic compound, and was formed by vapor-depositing PCBBiF onto a glass substrate to a thickness of 40 nm.

[0573] Sample 7 is a mixed film using multiple aromatic compounds, and was formed on a glass substrate by co-evaporation of 2mpPCBPDBq and NBPhen to a thickness of 20 nm in a weight ratio of 0.5:0.5 (=2mpPCBPDBq:NBPhen).

[0574] Sample 8 is a mixed film using multiple heteroaromatic compounds, and is composed of 2mpPCBPDBq, PCBBiF, and Ir(tBuppm) on a glass substrate. ３and a weight ratio of 0.8:0.2:0.06 (=2mpPCBPDBq:PCBBiF:Ir(tBuppm) ３ After co-evaporating a 40 nm layer of NBPhen, a 20 nm layer of NBPhen was evaporated.

[0575] Sample 9 is a mixed film using multiple heteroaromatic compounds, and is composed of 2mpPCBPDBq, PCBBiF, and Ir(tBuppm) on a glass substrate. ３ and a weight ratio of 0.8:0.2:0.06 (=2mpPCBPDBq:PCBBiF:Ir(tBuppm) ３ After that, 2mpPCBPDBq and NBPhen were co-deposited to a thickness of 20 nm so as to have a weight ratio of 0.5:0.5 (=2mpPCBPDBq:NBPhen).

[0576] Each sample prepared in this manner was observed visually and under an optical microscope (Olympus Corporation, Semiconductor / FPD Inspection Microscope MX61L).

[0577] Photographs of the samples produced in this example (observed at 100x magnification) are shown in Figures 20 and 21. As comparative examples, each sample without baking (ref) is also shown.

[0578] The structures of the samples prepared in this example and the results of their observations are shown in Table 1. In Table 1, a circle indicates that no crystals were formed, and a cross indicates that crystals were formed. Those for which a clear determination could not be made are marked with a triangle.

[0579]

[0580] From the above results, it was found that Samples 3 and 7, which are mixed films using multiple heteroaromatic compounds, are less likely to generate crystals than Samples 4 and 5, which are laminated films using multiple heteroaromatic compounds. Therefore, it was found that mixed films using multiple heteroaromatic compounds have improved heat resistance. In particular, when comparing Samples 4 and 7, although both contain the same heteroaromatic compounds, Sample 4, which is a laminated film, crystallized at 100°C, while Sample 7, which is a mixed film, did not crystallize up to 150°C. This shows that mixed films using multiple π-electron-deficient heteroaromatic compounds are particularly effective in improving heat resistance.

[0581] Furthermore, the above results indicate that even materials with relatively good heat resistance as single films may crystallize at low temperatures when stacked. Comparing Samples 5 and 8 with Sample 9, which are stacked with multiple films, Sample 5 crystallized at 100°C, Sample 8 crystallized at 80°C, while Sample 9 did not clearly crystallize until 130°C. Compared to a single-material electron-transport layer, constructing the electron-transport layer from a mixed film using multiple heteroaromatic compounds effectively improved heat resistance by 30°C or more. Light-emitting devices are often constructed by stacking multiple organic compounds. Therefore, the heat resistance of a light-emitting device according to one embodiment of the present invention can be significantly improved.

[0582] The results of Example 1 showed that the heat resistance of the heteroaromatic compound and the organic compound used in the electron transport layer of the light-emitting device according to one embodiment of the present invention, when used as a mixed film, is improved compared to a laminate film in which these single layer films are stacked. Therefore, a light-emitting device 1 using a mixed film of a heteroaromatic compound and an organic compound in the electron transport layer and a comparative light-emitting device 1 using a laminate film of a heteroaromatic compound and an organic compound were fabricated, and the characteristics of each device were compared. The device structure and its characteristics are described below. The specific configurations of the light-emitting device 1 and the comparative light-emitting device 1 used in this example are shown in Table 1. The chemical formulas of the materials used in this example are shown below.

[0583]

[0584]

[0585] <<Fabrication of Light-Emitting Device 1>> The light-emitting device 1 shown in this example has a structure in which a hole injection layer 911, a hole transport layer 912, a light-emitting layer 913, an electron transport layer 914, and an electron injection layer 915 are sequentially stacked on a first electrode 901 formed on a substrate 900, as shown in FIG. 22 , and a second electrode 903 is stacked on the electron injection layer 915.

[0586] First, a first electrode 901 was formed on a substrate 900. The electrode area was 4 mm ２ The dimensions of the substrate 900 were 2 mm×2 mm. A glass substrate was used as the substrate 900. The first electrode 901 was formed by depositing indium tin oxide containing silicon oxide (ITSO) to a thickness of 70 nm by sputtering.

[0587] Here, as a pretreatment, the surface of the substrate was washed with water, baked at 200° C. for 1 hour, and then subjected to UV ozone treatment for 370 seconds. −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and was subjected to vacuum baking at 170° C. for 60 minutes in a heating chamber within the vacuum deposition apparatus, after which the substrate was allowed to cool for about 30 minutes.

[0588] Next, a hole injection layer 911 was formed on the first electrode 901. The hole injection layer 911 was formed by evaporating the solution in a vacuum evaporation apparatus for 10 minutes. −４ After reducing the pressure to 10 Pa, N-(1,1′-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (i) and a fluorine-containing electron acceptor material (OCHD-003) with a molecular weight of 672 were co-evaporated to a thickness of 10 nm in a weight ratio of 1:0.03 (= PCBBiF:OCHD-003).

[0589] Next, a hole transport layer 912 was formed on the hole injection layer 911. The hole transport layer 912 was formed by vapor deposition of PCBBiF to a thickness of 50 nm.

[0590] Next, a light-emitting layer 913 was formed on the hole-transporting layer 912 .

[0591] The light-emitting layer 913 is composed of 2-[4′-(9-phenyl-9H-carbazol-3-yl)-3,1′-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq) represented by the structural formula (ii) above, PCBBiF, and tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(tBuppm) ３ ) in a weight ratio of 2 mp PCBPDBq: PCBBiF: Ir(tBuppm) ３ The layers were co-evaporated to a thickness of 50 nm so that the ratio was 0.8:0.2:0.05.

[0592] Next, an electron transport layer 914 was formed on the light-emitting layer 913. The electron transport layer 914 was formed by co-evaporating 2mpPCBPDBq and 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) represented by the above structural formula (iv) to a thickness of 30 nm, so that the weight ratio of 2mpPCBPDBq:NBPhen was 1:1.

[0593] Next, an electron injection layer 915 was formed on the electron transport layer 914. The electron injection layer 915 was formed by vapor deposition using lithium fluoride (LiF) so as to have a film thickness of 1 nm.

[0594] Next, a second electrode 903 was formed on the electron injection layer 915. The second electrode 903 was formed by vapor deposition of aluminum so as to have a film thickness of 200 nm. In this example, the second electrode 903 functions as a cathode.

[0595] Through the above steps, a light-emitting device 1 including an EL layer sandwiched between a pair of electrodes was formed on a substrate 900. Note that the hole injection layer 911, the hole transport layer 912, the light-emitting layer 913, the electron transport layer 914, and the electron injection layer 915 described in the above steps are functional layers that constitute the EL layer in one embodiment of the present invention. Furthermore, in all of the vapor deposition steps in the above-described manufacturing method, vapor deposition using a resistance heating method was used.

[0596] The fabricated light-emitting device 1 was sealed in a glove box with a nitrogen atmosphere to prevent exposure to the atmosphere (a sealant was applied to the periphery of the element, and UV treatment and heat treatment at 80° C. for 1 hour were performed during sealing).

[0597] <<Fabrication of Comparative Light-Emitting Device 1>> Comparative light-emitting device 1 was fabricated in the same manner as light-emitting device 1, except that instead of forming the electron transport layer 914 by co-evaporating 2mpPCBPDBq and NBPhen, 2mpPCBPDBq was deposited to a thickness of 10 nm and then NBPhen was deposited to a thickness of 20 nm.

[0598] <Operation Characteristics of Light-Emitting Device 1> The luminance-current density characteristics of light-emitting device 1 and comparative light-emitting device 1 are shown in Fig. 23, the current efficiency-luminance characteristics in Fig. 24, the luminance-voltage characteristics in Fig. 25, the current-voltage characteristics in Fig. 26, the external quantum efficiency-luminance characteristics in Fig. 27, and the emission spectrum in Fig. 28. The luminance-current characteristics of light-emitting device 1 and comparative light-emitting device 1 at 1000 cd / m ２ The main characteristics in this range are shown in Table 3. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0599]

[0600] 23 to 28 and Table 3, it was found that the light-emitting device 1 according to one embodiment of the present invention exhibited operating characteristics equivalent to those of the comparative light-emitting device 1.

[0601] Next, a reliability test was conducted on each light-emitting device. The results of the reliability test on light-emitting device 1 and comparative light-emitting device 1 are shown in Figure 29. In Figure 29, the vertical axis represents normalized luminance (%) when the initial luminance is taken as 100%, and the horizontal axis represents the device operating time (h). In the reliability test, each light-emitting device was subjected to a current of 50 mA / cm ２ A driving test was carried out at a constant current density of 1000 kJ / s.

[0602] The results shown in FIG. 29 indicate that the light-emitting device 1 according to one embodiment of the present invention has excellent reliability equivalent to that of the comparative light-emitting device 1.

[0603] This example describes a synthesis method for 2-[4′-(9-phenyl-9H-carbazol-3-yl)-3,1′-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), which was used in Example 1 and Example 2. The structural formula of 2mpPCBPDBq is shown below.

[0604]

[0605] Synthesis of 2mpPCBPDBq: 6.9 g (17 mmol) of 3-(4-bromophenyl)-9-phenylcarbazole, 4.4 g (17 mmol) of bis(pinacolato)diborane, 0.17 g (0.4 mmol) of 2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl (tBuXPhos), 4.0 g (40 mmol) of potassium acetate, and 90 mL of xylene were placed in a 200 mL three-neck flask. The flask was then degassed under reduced pressure and purged with nitrogen. The mixture was heated to 80°C, and then [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (Pd(dppf)Cl ２ 0.17 mg (0.2 mmol) of 2-hydroxybenzoic acid was added to the mixture, and the mixture was stirred at 120° C. for 10 hours.

[0606] To the resulting mixture were added 5.8 g (17 mmol) of 2-(3-chlorophenyl)dibenzo[f,h]quinoxaline, 13 g (40 mmol) of cesium carbonate, and 0.18 mg (0.4 mmol) of tBuXPhos. The mixture was degassed under reduced pressure and then placed under a nitrogen stream. The mixture was heated to 80° C. and then Pd(dppf)Cl ２ 0.16 mg (0.2 mmol) of was added, and the mixture was heated and stirred at 130°C for 3 hours, then at 150°C for 15 hours. After stirring, the precipitated solid was collected by suction filtration and washed with water and ethanol. The obtained solid was suction filtered using 1 L of toluene through Celite (Wako Pure Chemical Industries, Ltd., catalog number: 537-02305) and alumina, and then recrystallized from toluene to obtain 1.4 g (yield: 12%) of the target white powder. The synthesis scheme is shown in formula (a-1) below.

[0607]

[0608] The obtained solid was purified by sublimation using a train sublimation method. Sublimation purification was performed by heating 1.3 g of the obtained solid at 340°C for 15 hours. The pressure during sublimation purification was 3.9 Pa, and the argon flow rate was 15 sccm. After sublimation purification, 1.5 g of the target solid was obtained at a recovery rate of 85%.

[0609] Nuclear magnetic resonance spectroscopy of the solid obtained above ( １ The results of the analysis by H-NMR are shown below. From these results, it was found that 2mpPCBPDBq was obtained in this example.

[0610] １ H-NMR (chloroform-d, 500MHz): δ = 7.32-7.35 (m, 1H), 7.446 (s, 1H), 7.454 (s, 1H ), 7.49-7.53 (m, 2H), 7.61-7.66 (m, 4H), 7.71-7.92 (m, 11H), 8.24 (d, J = 8.0H z, 1H), 8.33 (d, J = 8.0Hz, 1H), 8.46 (sd, J = 1.0Hz, 1H), 8.67-8.68 (m, 3H), 9.2 6 (dd, J=7.8Hz, J=1.3Hz, 1H), 9.47 (dd, J=8.0Hz, J=1.5Hz, 1H), 9.48 (s, 1H).

[0611] 41a: pixel circuit, 41b: pixel circuit, 42a: pixel circuit, 42b: pixel circuit, 43a: pixel circuit, 43b: pixel circuit, 51a: wiring, 51b: wiring, 52a: wiring, 52b: wiring, 52c: wiring,...

Claims

1. a first light emitting device and a second light emitting device adjacent to each other on an insulating plane; the first light emitting device has a first anode, a first cathode, and a first EL layer sandwiched between the first anode and the first cathode; the second light emitting device has a second anode, a second cathode, and a second EL layer sandwiched between the second anode and the second cathode; the first EL layer has at least a first light-emitting layer and a first electron transport layer; the first electron transport layer is located between the first light emitting layer and the first cathode; the second EL layer includes at least a second light-emitting layer and a second electron transport layer; the second electron transport layer is located between the second light emitting layer and the second cathode; the first electron transport layer includes a first heteroaromatic compound having at least a first heteroaromatic ring and a first organic compound different from the first heteroaromatic compound; the second electron transport layer includes a second heteroaromatic compound having at least a second heteroaromatic ring and a second organic compound different from the second heteroaromatic compound; an end of the first light-emitting layer and an end of the first electron transport layer are substantially aligned at a first end when viewed in a direction perpendicular to the insulating plane; an end of the second light-emitting layer and an end of the second electron transport layer are substantially aligned at a second end when viewed in a direction perpendicular to the insulating plane; A light emitting device, wherein the distance between the first end and the second end facing each other is 2 μm to 5 μm.

2. In claim 1, the first electron transport layer is composed of the first heteroaromatic compound and the first organic compound; The second electron transport layer of the light emitting device is composed of the second heteroaromatic compound and the second organic compound.

3. In claim 1 or 2, the first heteroaromatic compound and the first organic compound are each contained in the first electron transport layer in an amount of 10% by weight or more; The second heteroaromatic compound and the second organic compound are each contained in the second electron transport layer at a content of 10% by weight or more.

4. In any one of claims 1 to 3, The light emitting device, wherein the first electron transport layer and the second electron transport layer do not contain a metal complex.

5. In any one of claims 1 to 4, The light emitting device, wherein the first electron transport layer and the second electron transport layer do not include an alkali metal complex or an alkaline earth metal complex.

6. In any one of claims 1 to 5, The light emitting device, wherein the first electron transport layer and the second electron transport layer do not include an alkali metal quinolinolate or an alkaline earth metal quinolinolate.

7. In any one of claims 1 to 6, the first EL layer has a first electron injection layer between the first electron transport layer and the first cathode and in contact with the first cathode; the second EL layer has a second electron injection layer between the second electron transport layer and the second cathode and in contact with the second cathode; The light emitting device, wherein the first electron injection layer and the second electron injection layer are contiguous in the first light emitting device and the second light emitting device.

8. a first light emitting device and a second light emitting device adjacent to each other on an insulating plane; the first light emitting device has a first anode, a first cathode, and a first EL layer sandwiched between the first anode and the first cathode; the second light emitting device has a second anode, a second cathode, and a second EL layer sandwiched between the second anode and the second cathode; The first EL layer has at least a light-emitting layer 1a, a first intermediate layer, a light-emitting layer 1b, and an electron transport layer 1b in this order from the first anode side, the electron transport layer 1b is located between the light emitting layer 1b and the first cathode, the second EL layer has at least a light-emitting layer 2a, a second intermediate layer, a light-emitting layer 2b, and an electron transport layer 2b in this order from the second anode side; the electron transport layer 2b is located between the light emitting layer 2b and the second cathode, the electron transport layer 1b includes a first heteroaromatic compound having at least a first heteroaromatic ring, and a first organic compound different from the first heteroaromatic compound; the electron transport layer 2b includes a second heteroaromatic compound having at least a second heteroaromatic ring and a second organic compound different from the second heteroaromatic compound, an end of the light-emitting layer 1 a and an end of the electron transport layer 1 b are substantially aligned at a first end when viewed in a direction perpendicular to the insulating plane; an end of the light-emitting layer 2 a and an end of the electron transport layer 2 b are substantially aligned at a second end when viewed from a direction perpendicular to the insulating plane; A light emitting device, wherein the distance between the first end and the second end facing each other is 2 μm to 5 μm.

9. In claim 8, the electron transport layer 1b is composed of the first heteroaromatic compound and the first organic compound, The electron transport layer 2b is formed from the second heteroaromatic compound and the second organic compound.

10. In claim 8 or claim 9, the first heteroaromatic compound and the first organic compound are each contained in the electron transport layer 1b in an amount of 10% by weight or more; The light emitting device, wherein the second heteroaromatic compound and the second organic compound are each contained in the electron transport layer 2b at a content of 10% by weight or more.

11. In any one of claims 8 to 10, The light-emitting device, wherein the electron transport layer 1b and the electron transport layer 2b do not contain a metal complex.

12. In any one of claims 8 to 11, The light-emitting device, wherein the electron transport layer 1b and the electron transport layer 2b do not contain an alkali metal complex or an alkaline earth metal complex.

13. In any one of claims 8 to 12, The light-emitting device, wherein the electron transport layer 1b and the electron transport layer 2b do not contain an alkali metal quinolinolate or an alkaline earth metal quinolinolate.

14. In any one of claims 8 to 13, the first EL layer has an electron transport layer 1a between the light emitting layer 1a and the first intermediate layer, the second EL layer has an electron transport layer 2a between the light emitting layer 2a and the second intermediate layer, The light-emitting device, wherein the electron transport layer 1a and the electron transport layer 2a have different structures from the electron transport layer 1b and the electron transport layer 2b, respectively.

15. In any one of claims 8 to 14, the first EL layer has an electron transport layer 1a between the light emitting layer 1a and the first intermediate layer, the second EL layer has an electron transport layer 2a between the light emitting layer 2a and the second intermediate layer, The light-emitting device in which the electron transport layer 1a and the electron transport layer 2a have the same configurations as the electron transport layer 1b and the electron transport layer 2b, respectively.

16. In claim 15, The light-emitting device, wherein the electron transport layer 1a and / or the electron transport layer 2a is made of one type of organic compound.

17. In any one of claims 8 to 16, The light-emitting device, wherein the first intermediate layer and the second intermediate layer are charge generating layers.

18. In any one of claims 8 to 17, the first EL layer has a first electron injection layer between the electron transport layer 1b and the first cathode and in contact with the first cathode; the second EL layer has a second electron injection layer between the electron transport layer 2b and the second cathode and in contact with the second cathode; The light emitting device, wherein the first electron injection layer and the second electron injection layer are contiguous in the first light emitting device and the second light emitting device.

19. In any one of claims 1 to 18, The light emitting device, wherein the first cathode and the second cathode are continuous in the first light emitting device and the second light emitting device.

20. A light emitting device according to any one of claims 1 to 19, An electronic device having at least one of a sensor, an operation button, a speaker, and a microphone.