Light emitting devices, light emitting apparatus, electronic device, and lighting device

Abstract

Provided is a light emitting device having high heat resistance in the manufacturing process. Provided is a light emitting device having a second electrode on a first electrode with an EL layer sandwiched therebetween, wherein the EL layer has at least a light emitting layer, a first electron transport layer, a second electron transport layer, and an electron injection layer, the first electron transport layer is provided on the light emitting layer, the second electron transport layer is provided on the first electron transport layer, an insulating layer is provided in contact with a side surface of the light emitting layer, a side surface of the first electron transport layer, and a side surface of the second electron transport layer, the electron injection layer is provided on the second electron transport layer, the insulating layer is located between the electron injection layer and the side surface of the light emitting layer, the side surface of the first electron transport layer, and the side surface of the second electron transport layer, and the second electron transport layer has a heteroaromatic compound having at least one heteroaromatic ring and an organic compound different from the heteroaromatic compound.

Description

Light-emitting device, light-emitting apparatus, electronic device and lighting apparatus

[0001] One embodiment of the present invention relates to a light-emitting device, a display device, a light-emitting device, a light-receiving and 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 element, 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 than liquid crystals and no need for backlighting, making them suitable for flat panel display elements. 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] Displays and lighting devices using such light-emitting devices are suitable for use in a variety of electronic devices, but research and development is ongoing to find light-emitting devices with even better characteristics.

[0006] Various methods for manufacturing light-emitting devices are known, and one method for producing high-definition light-emitting devices is to form a light-emitting layer without using a fine metal mask. One example of such a method is a method for manufacturing an organic EL display (Patent Document 1), which includes the steps of: depositing a first luminescent organic material containing a mixture of a host material and a dopant material above an electrode array including first and second pixel electrodes formed above an insulating substrate to form a first light-emitting layer as a continuous film extending across a display area including the electrode array; irradiating a portion of the first light-emitting layer located above the second pixel electrodes with ultraviolet light without irradiating a portion of the first light-emitting layer located above the first pixel electrodes with ultraviolet light; depositing a second luminescent organic material containing a mixture of a host material and a dopant material, different from the first luminescent organic material, on the first light-emitting layer to form a second light-emitting layer as a continuous film extending across the display area; and forming a counter electrode above the second light-emitting layer.

[0007] JP 2012-160473 A

[0008] An object of one embodiment of the present invention is to provide a novel light-emitting device with excellent convenience, usefulness, or reliability.Another object of one embodiment of the present invention is to provide a novel light-emitting device with excellent convenience, usefulness, or reliability.Another object of one embodiment of the present invention is to provide a novel electronic device with excellent convenience, usefulness, or reliability.Another object of one embodiment of the present invention is to provide a novel lighting device with excellent convenience, usefulness, or reliability.

[0009] Another object of one embodiment of the present invention is to provide a light-emitting device with high heat resistance.Another object of one embodiment of the present invention is to provide a light-emitting device with high heat resistance in a manufacturing process.Another object of one embodiment of the present invention is to provide a highly reliable light-emitting device.Another object of one embodiment of the present invention is to provide a light-emitting device, a light-emitting device, an electronic device, a display device, and an electronic device with low power consumption.Another object of one embodiment of the present invention is to provide a light-emitting device, a light-emitting device, an electronic device, a display device, and an electronic device with low power consumption and high reliability.

[0010] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these will become apparent from the description of the specification, drawings, claims, etc., and it is possible to extract other problems from the description of the specification, drawings, claims, etc.

[0011] One embodiment of the present invention is a light-emitting device including a first electrode and an EL layer sandwiched between them. The EL layer includes at least a light-emitting layer, a first electron-transport layer, a second electron-transport layer, and an electron-injection layer. The first electron-transport layer is located on the light-emitting layer, the second electron-transport layer is located on the first electron-transport layer, and insulating layers are in contact with side surfaces of the light-emitting layer, the first electron-transport layer, and the second electron-transport layer, and the electron-injection layer is located on the second electron-transport layer. The insulating layers are located among the side surfaces of the light-emitting layer, the first electron-transport layer, and the second electron-transport layer, and the electron-injection layer. The second electron-transport layer includes a heteroaromatic compound having at least one heteroaromatic ring and an organic compound different from the heteroaromatic compound.

[0012] Another embodiment of the present invention is a light-emitting device including a second electrode over a first electrode with an EL layer sandwiched therebetween, the EL layer including at least a light-emitting layer, a first electron-transport layer, a second electron-transport layer, and an electron-injection layer, the first electron-transport layer over the light-emitting layer, the second electron-transport layer over the first electron-transport layer, insulating layers in contact with side surfaces of the light-emitting layer, the first electron-transport layer, and the second electron-transport layer, and the electron-injection layer over the second electron-transport layer, the insulating layers being positioned among the side surfaces of the light-emitting layer, the first electron-transport layer, and the second electron-transport layer, and the electron-injection layer, the second electron-transport layer including a first heteroaromatic compound having at least one heteroaromatic ring and an organic compound different from the first heteroaromatic compound, and the first electron-transport layer including a second heteroaromatic compound having at least one heteroaromatic ring.

[0013] In the light-emitting device having each of the above configurations, the organic compound preferably has at least one heteroaromatic ring.

[0014] In the light-emitting devices having the above-described structures, the heteroaromatic ring preferably has any one of a pyridine skeleton, a diazine skeleton, a triazine skeleton, and a polyazole skeleton.

[0015] In the light-emitting devices having the above-described configurations, the heteroaromatic ring is preferably a condensed heteroaromatic ring having a condensed ring structure.

[0016] In the light-emitting device having the above configuration, the fused heteroaromatic ring is preferably any one of a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a dibenzoquinoxaline ring, a phenanthroline ring, a furodiazine ring, and a benzimidazole ring.

[0017] Another embodiment of the present invention is a light-emitting device including the light-emitting device having any of the above structures and a transistor or a substrate.

[0018] Another embodiment of the present invention provides a light-emitting device including a first light-emitting device and a second light-emitting device adjacent to each other. The first light-emitting device includes a second electrode over a first electrode with a first EL layer sandwiched therebetween. The first EL layer includes at least a first light-emitting layer, a first electron-transport layer, a second electron-transport layer, and an electron-injection layer. The first electron-transport layer is over the first light-emitting layer, the second electron-transport layer is over the first electron-transport layer, and a first insulating layer is in contact with a side surface of the first light-emitting layer, a side surface of the first electron-transport layer, and a side surface of the second electron-transport layer. The electron-injection layer is over the second electron-transport layer. The first insulating layer is located between the side surface of the first light-emitting layer, the side surface of the first electron-transport layer, and the side surface of the second electron-transport layer and the electron-injection layer. the second EL layer has at least a second light-emitting layer, a third electron-transporting layer, a fourth electron-transporting layer, and an electron-injecting layer; the third electron-transporting layer is on the second light-emitting layer; the fourth electron-transporting layer is on the third electron-transporting layer; a second insulating layer is in contact with a side surface of the second light-emitting layer and a side surface of the third electron-transporting layer; and the electron-injecting layer is on the fourth electron-transporting layer; the second insulating layer is located between the side surface of the second light-emitting layer and the side surface of the third electron-transporting layer and the electron-injecting layer; and the second electron-transporting layer and the fourth electron-transporting layer have a heteroaromatic compound having at least one heteroaromatic ring and an organic compound different from the heteroaromatic compound.

[0019] Another embodiment of the present invention includes a first light-emitting device and a second light-emitting device adjacent to each other. The first light-emitting device has a second electrode over a first electrode with a first EL layer sandwiched therebetween. The first EL layer has at least a first light-emitting layer, a first electron-transport layer, a second electron-transport layer, and an electron-injection layer. The first electron-transport layer is over the first light-emitting layer, and the second electron-transport layer is over the first electron-transport layer. A first insulating layer is in contact with a side surface of the first light-emitting layer, a side surface of the first electron-transport layer, and a side surface of the second electron-transport layer, and the electron-injection layer is over the second electron-transport layer. The first insulating layer is positioned between the electron-injection layer and the side surface of the first light-emitting layer, the side surface of the first electron-transport layer, and the side surface of the second electron-transport layer. The second light-emitting device has a second electrode over a third electrode with the second EL layer sandwiched therebetween. the second EL layer has at least a second light-emitting layer, a third electron-transporting layer, a fourth electron-transporting layer, and an electron-injecting layer; the second EL layer has the third electron-transporting layer on the second light-emitting layer, the fourth electron-transporting layer on the third electron-transporting layer, a second insulating layer in contact with a side surface of the second light-emitting layer and a side surface of the third electron-transporting layer; and the electron-injecting layer on the fourth electron-transporting layer; the second insulating layer is located between the side surface of the second light-emitting layer and a side surface of the third electron-transporting layer and the electron-injecting layer; the second electron-transporting layer and the fourth electron-transporting layer have a first heteroaromatic compound having at least one heteroaromatic ring and an organic compound different from the first heteroaromatic compound; and the first electron-transporting layer and the third electron-transporting layer have a second heteroaromatic compound having at least one heteroaromatic ring.

[0020] In the light-emitting device having each of the above configurations, the organic compound preferably has at least one heteroaromatic ring.

[0021] In the light-emitting device having each of the above configurations, the heteroaromatic ring preferably has any one of a pyridine skeleton, a diazine skeleton, a triazine skeleton, and a polyazole skeleton.

[0022] In the light-emitting device having each of the above configurations, the heteroaromatic ring is preferably a condensed heteroaromatic ring having a condensed ring structure.

[0023] In the light emitting device having the above configuration, the fused heteroaromatic ring is preferably any one of a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a dibenzoquinazoline ring, a phenanthroline ring, a phlodiazin ring, and a benzimidazole ring.

[0024] In the light-emitting devices having the above configurations, it is preferable that the electron injection layer is located between a side surface of the first electron transport layer, a side surface of the second electron transport layer, a side surface of the third electron transport layer, a side surface of the fourth electron transport layer, a side surface of the first light-emitting layer, and a side surface of the second light-emitting layer and the second electrode.

[0025] In addition to the above-described light-emitting devices, those having a layer (e.g., a cap layer) containing an organic compound in contact with an electrode are also included in the light-emitting device and are included in the scope of the present invention. Furthermore, light-emitting devices having a transistor, a substrate, etc. in addition to the light-emitting device are also included in the scope of the invention. Furthermore, electronic devices and lighting devices having these light-emitting devices and any of a detection unit, an input unit, or a communication unit are also included in the scope of the invention.

[0026] One embodiment of the present invention includes a light-emitting device having a light-emitting device, and further includes a lighting device having a light-emitting device in its category. Therefore, the term "light-emitting device" in this specification refers to an image display device or a light source (including a lighting device). The term "light-emitting device" also includes a module in which a connector such as a flexible printed circuit (FPC) or a tape carrier package (TCP) 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 by a chip-on-glass (COG) method.

[0027] In this specification, the names of the source and drain of a transistor are interchangeable depending on the polarity of the transistor and the level of the potential applied to each terminal. Generally, in an n-channel transistor, a terminal to which a low potential is applied is called a source, and a terminal to which a high potential is applied is called a drain. In a p-channel transistor, a terminal to which a low potential is applied is called a drain, and a terminal to which a high potential is applied is called a source. In this specification, for convenience, the connection relationship of a transistor may be described assuming that the source and drain are fixed, but in reality, the names of the source and drain are interchangeable depending on the above-mentioned potential relationship.

[0028] In this specification, the source of a transistor refers to a source region that is part of a semiconductor film that functions as an active layer, or a source electrode connected to the semiconductor film. Similarly, the drain of a transistor refers to a drain region that is part of the semiconductor film, or a drain electrode connected to the semiconductor film. Furthermore, the gate refers to a gate electrode.

[0029] In this specification, a state in which transistors are connected in series means, for example, a state in which only one of the source or drain of a first transistor is connected to only one of the source or drain of a second transistor, and a state in which transistors are connected in parallel means a state in which one of the source or drain of a first transistor is connected to one of the source or drain of a second transistor, and the other of the source or drain of the first transistor is connected to the other of the source or drain of the second transistor.

[0030] In this specification, "connection" means an electrical connection, and corresponds to a state in which a current, voltage, or potential can be supplied or transmitted. Therefore, a connected state does not necessarily refer to a direct connection, but also includes a state in which a current, voltage, or potential can be supplied or transmitted via a circuit element such as a wiring, resistor, diode, or transistor.

[0031] In this specification, even when components that appear independent on a circuit diagram are connected to each other, in reality, one conductive film may have the functions of multiple components, for example, when part of a wiring functions as an electrode. In this specification, the term "connection" also includes such cases where one conductive film has the functions of multiple components.

[0032] One embodiment of the present invention can provide a novel light-emitting device with excellent convenience, usefulness, or reliability. Another embodiment of the present invention can provide a novel light-emitting device with excellent convenience, usefulness, or reliability. Another embodiment of the present invention can provide a novel electronic device with excellent convenience, usefulness, or reliability. Another embodiment of the present invention can provide a novel lighting device with excellent convenience, usefulness, or reliability.

[0033] One embodiment of the present invention can provide a light-emitting device with high heat resistance. Another embodiment of the present invention can provide a light-emitting device with high heat resistance in a manufacturing process. Another embodiment of the present invention can provide a light-emitting device with high reliability. Another embodiment of the present invention can provide a light-emitting device, a light-emitting device, an electronic device, a display device, and an electronic device with low power consumption. Another embodiment of the present invention can provide a light-emitting device, a light-emitting device, an electronic device, a display device, and an electronic device with low power consumption and high reliability.

[0034] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc.

[0035] FIGS. 1A to 1C are diagrams illustrating a configuration of a light-emitting device according to an embodiment. FIGS. 2A and 2B are diagrams illustrating a configuration of a light-emitting device according to an embodiment. FIGS. 3A and 3B are diagrams illustrating a light-emitting device according to an embodiment. FIGS. 4A and 4B are diagrams illustrating a method for manufacturing a light-emitting device according to an embodiment. FIGS. 5A to 5C are diagrams illustrating a method for manufacturing a light-emitting device according to an embodiment. FIGS. 6A to 6C are diagrams illustrating a method for manufacturing a light-emitting device according to an embodiment. FIGS. 7A and 7B are diagrams illustrating a method for manufacturing a light-emitting device according to an embodiment. FIG. 8 is a diagram illustrating a light-emitting device according to an embodiment. FIGS. 9A and 9B are diagrams illustrating a light-emitting device according to an embodiment. FIGS. 10A and 10B are diagrams illustrating a light-emitting device according to an embodiment. FIGS. 11A and 11B are diagrams illustrating a light-emitting device according to an embodiment. FIGS. 12A and 12B are diagrams illustrating a light-emitting device according to an embodiment. FIGS. 13A to 13E are diagrams illustrating an electronic device according to an embodiment. FIGS. 14A to 14E are diagrams illustrating an electronic device according to an embodiment. FIGS. 15A and 15B are diagrams illustrating an electronic device according to an embodiment. FIGS. 16A and 16B are diagrams illustrating an electronic device according to an embodiment. FIG. 17 is a diagram illustrating an electronic device according to an embodiment. FIGS. 18A to 18E are photographs according to an example. FIGS. 19A to 19D are photographs according to an example. FIG. 20 is a diagram illustrating the configuration of a light-emitting device according to an example. FIG. 21 is a diagram illustrating the luminance-current density characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 22 is a diagram illustrating the current efficiency-luminance characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 23 is a diagram illustrating the luminance-voltage characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 24 is a diagram illustrating the current-voltage characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 25 is a diagram illustrating the external quantum efficiency-luminance characteristics of light-emitting device 1 and comparative light-emitting device 1. FIG. 26 is a diagram illustrating the emission spectra of light-emitting device 1 and comparative light-emitting device 1. FIG. 27 is a diagram illustrating the reliability of light-emitting device 1 and comparative light-emitting device 1.

[0036] 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.

[0037] Embodiment 1 In this embodiment, a structure of a light-emitting device according to one embodiment of the present invention will be described with reference to FIGS.

[0038] 1A is a cross-sectional view illustrating a structure of a light-emitting device 100 according to one embodiment of the present invention. Also, FIGS. 1B and 1C are cross-sectional views illustrating a more specific structure of the light-emitting device 100.

[0039] As shown in FIGS. 1A, 1B, and 1C, the light-emitting device 100 has a first electrode 101 and a second electrode 102, and has a structure in which a hole injection / transport layer 104, a light-emitting layer 113, a first electron transport layer 108-1, a second electron transport layer 108-2, and an electron injection layer 109 are sequentially stacked between the first electrode 101 and the second electrode 102.

[0040] The second electron transport layer 108-2 includes a heteroaromatic compound having at least one heteroaromatic ring and an organic compound other than the heteroaromatic compound. The proportions of the heteroaromatic compound and the organic compound in the materials constituting the second electron transport layer 108-2 are preferably 10% or more, preferably 20% or more, and more preferably 30% or more, because this significantly improves heat resistance. Furthermore, the organic compound preferably has at least one heteroaromatic ring. In other words, the second electron transport layer 108-2 includes a heteroaromatic compound and an organic compound, or multiple types of heteroaromatic compounds, which are organic compounds with high electron transport properties (preferably a mixed film). When the heteroaromatic ring in the heteroaromatic compound is a fused heteroaromatic ring, thermal properties such as the glass transition temperature (Tg) are improved. However, a single film of the heteroaromatic compound has strong molecular interactions, making it difficult to form a complete glass 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 heteroaromatic ring is a fused heteroaromatic ring, by having a structure including a plurality of heteroaromatic compounds, crystallization of the heteroaromatic compound can be suppressed, that is, the glass transition temperature can be improved while preventing the film from crystallizing at a temperature equal to or lower than Tg.

[0041] The heteroaromatic compound is a heteroaromatic compound that is included in organic compounds and has at least one heteroaromatic ring.

[0042] The heteroaromatic ring has any one of a pyridine skeleton, a diazine skeleton, a triazine skeleton, and a polyazole skeleton.

[0043] The heteroaromatic ring also includes a condensed heteroaromatic ring having a condensed ring structure.

[0044] Examples of the fused heteroaromatic ring include a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a dibenzoquinazoline ring, a phenanthroline ring, a phlodiazin ring, and a benzimidazole ring.

[0045] By configuring the second electron transport layer 108-2 to contain a heteroaromatic compound and an organic compound or a plurality of types of heteroaromatic compounds, crystallization during heating can be suppressed compared to a configuration including a single material. This improves the heat resistance of the second electron transport layer 108-2. Therefore, the second electron transport layer 108-2 has higher heat resistance than the first electron transport layer 108-1.

[0046] The first electron transport layer 108-1 may be a layer made using one type of heteroaromatic compound, a layer made using a heteroaromatic compound and an organic compound, or a layer made using a plurality of heteroaromatic compounds.

[0047] Electron-transporting materials such as heteroaromatic compounds and organic compounds that can be used in the first electron-transporting layer 108-1 and the second electron-transporting layer 108-2 will be described in more detail in later embodiments. In the light-emitting device of one embodiment of the present invention, the electron-transporting 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 quinolinol complexes and alkaline earth metal quinolinol complexes.

[0048] The electron injection layer 109 is part of the EL layer 103, but as shown in FIGS. 1B and 1C , it can have a different shape from the other layers of the EL layer 103 (the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2). Typically, when some layers of the EL layer have a different shape from the other layers, the manufacturing process can be heated to high temperatures, which can cause problems such as crystallization of the other layers and reduce the reliability and brightness of the light-emitting device. However, because the manufacturing process of the light-emitting device 100 can only be heated to high temperatures after the formation of the second electron transport layer 108-2, which has high heat resistance, this can prevent a decrease in the reliability and brightness of the light-emitting device 100. Therefore, in the light-emitting device 100, the electron injection layer 109 can have a different shape from the other layers of the EL layer 103 (the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2).

[0049] 1B and 1C, the electron injection layer 109 and the second electrode 102 can have the same shape. Since the electron injection layer 109 and the second electrode 102 can be layers common to a plurality of light-emitting devices, the manufacturing process of the light-emitting device 100 can be simplified and throughput can be improved.

[0050] In the EL layer 103, the electron injection layer 109 can be formed into a different shape by using a mask different from that used to process the other layers (the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2) of the EL layer 103. In other words, different shapes mean different shapes in a plan view (top view).

[0051] In addition, when two or more layers are formed to have the same shape, the same mask can be used to form the layers in the same shape in a plan view (top view).

[0052] Therefore, the ends (side surfaces) of the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2 have substantially the same surface (or are substantially aligned in a plan view (top view)). On the other hand, the end (side surface) of the electron injection layer 109 is not located on substantially the same plane as the ends (side surfaces) of the other layers of the EL layer 103 (the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2).

[0053] 1C , the light-emitting device 100 may also include an insulating layer 107. The insulating layer 107 contacts the side surfaces of the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2. The insulating layer 107 is located between the electron injection layer 109 and the side surfaces of the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2.

[0054] The insulating layer 107 can protect the side surfaces of the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2. Even in a configuration in which the second electrode 102 is adjacent to the side surfaces of the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2 as shown in FIG. 1C , the insulating layer 107 may prevent electrical continuity between the second electrode 102 and the hole injection / transport layer 104. The insulating layer 107 may also prevent electrical continuity between the second electrode 102 and the first electrode 101. Therefore, various structures can be applied to the light-emitting device 100. For example, when a plurality of light-emitting devices 100 are arranged side by side, the electron injection layers 109 and second electrodes 102 of adjacent light-emitting devices 100 may be connected to each other.

[0055] 1B , even if the second electrode 102 is configured to be adjacent to the side surfaces of the hole injection / transport layer 104, the side surfaces of the light-emitting layer 113, the side surfaces of the first electron transport layer 108-1, and the second electron transport layer 108-2, the light-emitting device 100 may not have the insulating layer 107 in some cases. For example, if the electrical conductivity between the second electrode 102 and the hole injection / transport layer 104 is sufficiently low, the light-emitting device 100 may not have the insulating layer 107. Furthermore, if the electrical conductivity between the second electrode 102 and the first electrode 101 is sufficiently low, the light-emitting device 100 may not have the insulating layer 107.

[0056] Materials that can be used for the first electrode 101, the second electrode 102, the hole injection / transport layer 104, the light-emitting layer 113, the electron injection layer 109, and the insulating layer 107 will be described in a later embodiment.

[0057] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0058] Embodiment Mode 2 In this embodiment mode, a light-emitting device using the organic compound shown in Embodiment Mode 1 will be described with reference to FIGS. 2A and 2B. FIG.

[0059] <<Specific Structure of Light-Emitting Device>> The light-emitting device shown in FIGS. 2A and 2B has a structure (single structure) in which an EL layer is sandwiched between a pair of electrodes.

[0060] <First Electrode and Second Electrode> The materials for forming the first electrode 101 and the second electrode 102 can be appropriately combined and used as long as they fulfill the function of the electrodes. For example, metals, alloys, electrically conductive compounds, and mixtures thereof can be appropriately used. Specific examples include In-Sn oxide (also referred to as ITO), In-Si-Sn oxide (also referred to as ITSO), In-Zn oxide, and In-W-Zn oxide. Other metals that can be used include aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), and neodymium (Nd), as well as alloys containing appropriate combinations of these metals. Other examples that can be used include elements belonging to Group 1 or 2 of the periodic table (e.g., lithium (Li), cesium (Cs), calcium (Ca), and strontium (Sr)) that are not listed above, rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing appropriate combinations of these, as well as graphene.

[0061] 2A and 2B , when the first electrode 101 is an anode, the EL layer 103 is formed by vacuum deposition on the first electrode 101. Specifically, as shown in Fig. 2B , the EL layer 103 is formed by sequentially stacking a hole injection layer 111, a hole transport layer 112, a light-emitting layer 113, an electron transport layer 114, and an electron injection layer 115 between the first electrode 101 and the second electrode by vacuum deposition.

[0062] <Hole Injection Layer> The hole injection layer 111 is a layer that injects holes from the first electrode 101, which is an anode, to the EL layer 103, and is a layer that contains an organic acceptor material or a material with high hole injection properties.

[0063] An organic acceptor material is a material that can generate holes in an organic compound by causing charge separation between the organic compound and another organic compound having a LUMO (Lowest Unoccupied Molecular Orbital) level value close to the HOMO (Highest Occupied Molecular Orbital) level value. Therefore, as the organic acceptor material, a compound having an electron-withdrawing group (a halogen group or a cyano group), such as a quinodimethane derivative, a chloranil derivative, or a hexaazatriphenylene derivative, can be used. For example, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F ４ Examples of organic acceptor materials that can be used include 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. Among organic acceptor materials, compounds such as HAT-CN in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms are particularly suitable because of their high acceptor properties and stable film quality against heat. In addition, [3]radialene derivatives having an electron-withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) are preferred because they have extremely high electron-accepting properties. Specifically, α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile], etc. can be used.

[0064] As a material with high hole injection properties, oxides of metals belonging to Groups 4 to 8 of the periodic table (transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc.) can be used. Specific examples include molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among the above, molybdenum oxide is preferred because it is stable in the air, has low hygroscopicity, and is easy to handle. In addition, phthalocyanine (abbreviated as H ２ Phthalocyanine compounds such as copper phthalocyanine (abbreviated as CuPc) and copper phthalocyanine (abbreviated as CuPc) can be used.

[0065] In addition to the above materials, low molecular weight compounds such as 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 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- Aromatic amine compounds such as tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), 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), and 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) can be used.

[0066] Also usable are polymer compounds (oligomers, dendrimers, polymers, etc.), 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). Alternatively, polymer compounds to which an acid has been added, such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS) and polyaniline / poly(styrenesulfonic acid) (abbreviation: PAni / PSS), can also be used.

[0067] Furthermore, as the material with high hole injection properties, a composite material containing a hole transport material and the above-mentioned organic acceptor material (electron accepting material) can also be used. In this case, electrons are extracted from the hole transport material by the organic acceptor material, generating holes in the hole injection layer 111, and the holes are injected into the light-emitting layer 113 via the hole transport layer 112. Note that the hole injection layer 111 may be formed of a single layer made of a composite material containing a hole transport material and an organic acceptor material (electron accepting material), or may be formed by laminating the hole transport material and the organic acceptor material (electron accepting material) as separate layers.

[0068] The hole transport material has a hole mobility of 1×10 when the square root of the electric field strength [V / cm] is 600. −６ cm ２ A substance having a hole mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher hole transporting property than electron transporting property.

[0069] As the hole transporting material, a material with high hole transporting properties such as a π-electron rich heteroaromatic compound (for example, a carbazole derivative, a furan derivative, or a thiophene derivative) or an aromatic amine (an organic compound having an aromatic amine skeleton) is preferred.

[0070] Examples of the carbazole derivatives (organic compounds having a carbazole skeleton) include bicarbazole derivatives (for example, 3,3′-bicarbazole derivatives), aromatic amines having a carbazolyl group, and the like.

[0071] Specific examples of the bicarbazole derivatives (e.g., 3,3′-bicarbazole derivatives) include 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-3,3′-bicarbazole (abbreviation: mBPCCBP), and 9-(2-naphthyl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: βNCCP).

[0072] Specific examples of the aromatic amine having a carbazolyl group include 4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,1′-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)]- ...triphenylamine (abbreviation: PCBiF), N-(1,1′-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)]-triphenylamine (abbreviation: PCBA1BP), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-triphenylamine (abbreviation: PCBiF), N-(1,1′-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)]-triphenylamine (abbreviation: PCBA1BP), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-triphenylamine (abbreviation: PCBA1BP), N-(4-biphenyl)-N-(9,9 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: PCBBiF), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4,4'-di(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: PCBBiF), 4,4'-diphenyl ... N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 9-phenyldiphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), ... ,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), 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 (abbreviation: PCzPCN1), 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1 -naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), and the like.

[0073] In addition to the above, examples of the carbazole derivatives include 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), and 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA).

[0074] Specific examples of the furan derivatives (organic compounds having a furan skeleton) include 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).

[0075] Specific examples of the thiophene derivative (organic compound having a thiophene skeleton) include organic compounds having a thiophene skeleton, such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV).

[0076] Specific examples of the aromatic amine include 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine (abbreviation: TPD), 4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 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). N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9H-fluoren-7-yl}phenylamine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9H-fluoren-7-yl] ... ,9′-bifluorene (abbreviation: DPASF), 2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9′-bifluorene (abbreviation: DPA2SF), 4,4′,4″-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1′-TNATA), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: m-MTDATA), N, N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), DNTPD, 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), 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: BBABnf(6)), 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 amine (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)naphthalene 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (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-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (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([1,1'-biphenyl-4-yl]amine N,N-bis([1,1′-biphenyl]-4-yl)-9,9′-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), 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-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), N,N-bis(9, ... N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, 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 are mentioned.

[0077] Other examples of hole-transporting materials that can be used include polymer compounds (oligomers, dendrimers, polymers, etc.) 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). Alternatively, polymer compounds to which an acid has been added, such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS) and polyaniline / poly(styrenesulfonic acid) (abbreviation: PAni / PSS), can also be used.

[0078] However, the hole transporting material is not limited to the above, and various known materials may be used alone or in combination as the hole transporting material.

[0079] The hole injection layer 111 can be formed by using various known film formation methods, for example, by using a vacuum deposition method.

[0080] <Hole Transport Layer> The hole transport layer 112 is a layer that transports holes injected from the first electrode 101 by the hole injection layer 111 to the light-emitting layer 113. Note that the hole transport layer 112 is a layer containing a hole transport material. Therefore, the hole transport layer 112 can be made of the same material as can be used for the hole injection layer 111.

[0081] In the light-emitting device of one embodiment of the present invention, the same organic compound as that used in the hole-transport layer 112 can be used for the light-emitting layer 113. Using the same organic compound for the hole-transport layer 112 and the light-emitting layer 113 is more preferable because holes can be efficiently transported from the hole-transport layer 112 to the light-emitting layer 113.

[0082] <Light-emitting layer> The light-emitting layer 113 is a layer containing a light-emitting substance. Note that, as the light-emitting substance that can be used for the light-emitting layer 113, substances that emit light of a color such as blue, purple, blue-purple, green, yellow-green, yellow, orange, or red can be used as appropriate. Furthermore, when a plurality of light-emitting layers are provided, a structure that emits different light colors (for example, white light emission obtained by combining light-emitting colors that are complementary to each other) can be obtained by using different light-emitting substances for each light-emitting layer. Furthermore, a stacked structure in which one light-emitting layer contains different light-emitting substances may be used.

[0083] The light-emitting layer 113 may contain one or more organic compounds (host materials, etc.) in addition to the light-emitting substance (guest material).

[0084] When a plurality of host materials are used in the light-emitting layer 113, it is preferable to use a substance having a larger energy gap than the energy gaps of the existing guest material and the first host material as the newly added second host material. Furthermore, it is preferable that the lowest singlet excitation energy level (S1 level) of the second host material be higher than the S1 level of the first host material, and the lowest triplet excitation energy level (T1 level) of the second host material be higher than the T1 level of the guest material. Furthermore, it is preferable that the lowest triplet excitation energy level (T1 level) of the second host material be higher than the T1 level of the first host material. With this structure, an exciplex can be formed using two types of host materials. To efficiently form an exciplex, it is particularly preferable to combine a compound that easily accepts holes (hole-transporting material) with a compound that easily accepts electrons (electron-transporting material). Furthermore, this structure can simultaneously achieve high efficiency, low voltage, and long life.

[0085] As the organic compound used as the host material (including the first host material and the second host material), as long as it satisfies the conditions for a host material used in an emitting layer, examples thereof include organic compounds such as the hole-transporting material that can be used in the hole-transporting layer 112 described above or the electron-transporting material that can be used in the electron-transporting layer 114 described below. The organic compound may also be an exciplex composed of multiple organic compounds (the first host material and the second host material described above). An exciplex (also referred to as an exciplex) that forms an excited state with multiple organic compounds 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 to singlet excitation energy. Furthermore, as a combination of multiple organic compounds that form an exciplex, for example, one of the organic compounds preferably contains a π-electron-deficient heteroaromatic compound and the other contains a π-electron-rich heteroaromatic compound. As a combination for forming an exciplex, one of the compounds may be a phosphorescent material such as an iridium, rhodium, or platinum-based organometallic complex or a metal complex.

[0086] The light-emitting substance that can be used for the light-emitting layer 113 is not particularly limited, and a light-emitting substance that converts singlet excitation energy into light emission in the visible light region or a light-emitting substance that converts triplet excitation energy into light emission in the visible light region can be used.

[0087] <Light-emitting substance that converts singlet excitation energy into light emission> Examples of light-emitting substances that can be used in the light-emitting layer 113 and that convert singlet excitation energy into light emission include the following fluorescent substances (fluorescent materials). Examples include pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives. Pyrene derivatives are particularly preferred because of their high light emission quantum yield. Specific examples of the pyrene derivative include N,N'-bis(3-methylphenyl)-N,N'-bis3[-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(dibenzofuran-2-yl)-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6FrAPrn), and N,N'-bis(dibenzothiophen-2-yl)-N, Examples thereof include N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-6-amine] (abbreviation: 1,6BnfAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-02), and N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03).

[0088] In addition, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2′-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4′-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2′-bipyridine (abbreviation: PAPP2BPy), N,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)phenyl]- N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), 4-(10-phenyl-9-anthryl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), 4-(10-phenyl-9-anthryl)-4'- (9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), 4-[4-(10-phenyl-9-anthryl)phenyl]-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPBA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenyl) N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), and the like can be used.

[0089] Further, N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-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: 2DPAPhA), 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-yl N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhTD), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-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 (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™), 1,6BnfAP rn-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), 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02), etc. In particular, pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 can be used.

[0090] <Light-Emitting Substance Converting Triplet Excitation Energy into Light Emission> Examples of light-emitting substances that convert triplet excitation energy into light emission and that can be used in the light-emitting layer 113 include phosphorescent substances (phosphorescent light-emitting substances) and thermally activated delayed fluorescence (TADF) materials that exhibit thermally activated delayed fluorescence.

[0091] A phosphorescent material is a compound that exhibits phosphorescence but does not exhibit fluorescence in a temperature range from low temperature to room temperature (i.e., from 77 K to 313 K). The phosphorescent material preferably contains a metal element with a large spin-orbit interaction, such as an organometallic complex, a metal complex (platinum complex), or a rare earth metal complex. Specifically, a transition metal element is preferred, and a platinum group element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt)) is particularly preferred. Among these, iridium is preferred because it can increase the transition probability associated with the direct transition between the singlet ground state and the triplet excited state.

[0092] <Phosphorescent Substances (450 nm to 570 nm: Blue or Green)> Examples of phosphorescent substances that exhibit blue or green and have an emission spectrum with a peak wavelength of 450 nm to 570 nm include the following substances.

[0093] For example, tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN ２ ]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp) ３ ]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz) ３ ]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b) ３ ]), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPr5btz) ３ ]), organometallic 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 organometallic 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 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’ ] Examples include organometallic complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand, such as iridium(III) acetylacetonate (abbreviation: FIr(acac)).

[0094] <Phosphorescent Substances (495 nm or More and 590 nm or Less: Green or Yellow)> Examples of phosphorescent substances that exhibit green or yellow and have an emission spectrum with a peak wavelength of 495 nm or more and 590 nm or less include the following substances.

[0095] For example, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm) ３ ]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm) ３ ]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm) ２ (acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm) ２ (acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm) ２ (acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm) ２(acac)]), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN]phenyl-κC}iridium(III) (abbreviation: [Ir(dmppm-dmp) ２ (acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm) ２ 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 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)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-phenyl-2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy) ２(4dppy)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC], [2-d ３ -methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d ３ -methyl-2-pyridinyl-κN ２ )phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d ３ ) ２ (mbfpypy-d ３ )), [2-(methyl-d ３ )-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro[2,3-b]pyridin-7-yl-κC]bis[5-(methyl-d ３ )-2-[5-(methyl-d ３ )-2-pyridinyl-κN]phenyl-κC]iridium(III) (abbreviation: Ir(5mtpy-d ６ ) ２ (mbfpypy-iPr-d ４ )), [2-d ３ -methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy) ２ (mbfpypy-d ３ )), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy) ２ organometallic iridium complexes having a pyridine skeleton, such as bis(2,4-diphenyl-1,3-oxazolato-N,C (mdppy)); ２’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(dpo) ２ (acac)]), bis{2-[4′-(perfluorophenyl)phenyl]pyridinato-N,C ２’} Iridium (III) acetylacetonate (abbreviation: [Ir(p-PF-ph) ２ (acac)]), bis(2-phenylbenzothiazolato-N,C ２’) Iridium(III) acetylacetonate (abbreviation: [Ir(bt) ２ In addition to organometallic complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)]), ３ (Phen)]).

[0096] <Phosphorescent Substances (570 nm to 750 nm: Yellow or Red)> Examples of phosphorescent substances that exhibit yellow or red and have an emission spectrum with a peak wavelength of 570 nm to 750 nm include the following substances.

[0097] For example, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm) ２ (dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm) ２ (dpm)]), (dipivaloylmethanato)bis[4,6-di(naphthalen-1-yl)pyrimidinato]iridium(III) (abbreviation: [Ir(dpm)] ２ organometallic 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)]), bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl-κC}(2,6-dimethyl-3,5-heptanedionato-κ ２ O,O')iridium(III) (abbreviation: [Ir(dmdppr-P) ２ (dibm)]), bis{4,6-dimethyl-2-[5-(4-cyano-2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ２ O,O′)iridium(III) (abbreviation: [Ir(dmdppr-dmCP) ２ (dpm)]), bis[2-(5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN)-4,6-dimethylphenyl-κC](2,2′,6,6′-tetramethyl-3,5-heptanedionato-κ ２ O,O′)iridium(III) (abbreviation: [Ir(dmdppr-dmp) ２ (dpm)]), (acetylacetonato)bis[2-methyl-3-phenylquinoxalinato-N,C ２’ ]iridium(III) (abbreviation: [Ir(mpq) ２ (acac)]), (acetylacetonato)bis(2,3-diphenylquinoxalinato-N,C ２’ ) Iridium(III) (abbreviation: [Ir(dpq) ２ (acac)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq) ２ organometallic 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 (acac)]), bis[4,6-dimethyl-2-(2-quinolinyl-κN)phenyl-κC](2,4-pentanedionato-κ ２ O,O')iridium(III) (abbreviation: [Ir(dmpqn) ２ (acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviation: [PtOEP]), or 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) ３ (Phen)]).

[0098] <TADF Material> The following materials can be used as the TADF material. A TADF material is a material that has a small difference between the S1 level and the T1 level (preferably 0.2 eV or less), can upconvert a triplet excited state to a singlet excited state with a small amount of thermal energy (reverse intersystem crossing), and efficiently emits light (fluorescence) from the singlet excited state. Conditions for efficiently obtaining thermally activated delayed fluorescence include an energy difference between the triplet excited energy level and the singlet excited energy level of 0 eV or more and 0.2 eV or less, preferably 0 eV or more and 0.1 eV or less. The delayed fluorescence in a TADF material refers to light emission that has a spectrum similar to that of ordinary fluorescence but has a significantly long lifetime. Its lifetime is 1 x 10 −６ seconds or more, preferably 1×10 −３ More than a second.

[0099] Examples of TADF materials include fullerene and its derivatives, acridine derivatives such as proflavine, and eosin. Also, examples of metal-containing porphyrins include those 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 (abbreviated as SnF ２ (Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF ２ (Meso IX)), hematoporphyrin-tin fluoride complex (abbreviation: SnF ２ (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF ２ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviation: SnF ２ (OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF２ (Etio I)), octaethylporphyrin-platinum chloride complex (abbreviation: PtCl ２ OEP) and the like.

[0100]

[0101] Other examples include 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxy) 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), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracen]-10'-one (abbreviation: ACRSA), 4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9'-phenyl-3,3'- Heteroaromatic compounds having a π-electron rich heteroaromatic compound and a π-electron deficient heteroaromatic compound, such as 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9′-phenyl-2,3′-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), may also be used.

[0102] In addition, a substance in which a π-electron-rich heteroaromatic compound and a π-electron-deficient heteroaromatic compound are directly bonded is particularly preferable because the donor property of the π-electron-rich heteroaromatic compound and the acceptor property of the π-electron-deficient heteroaromatic compound are both strong, and the energy difference between the singlet excited state and the triplet excited state is small.

[0103]

[0104] In addition to the above, examples of materials capable of converting triplet excitation energy into luminescence include nanostructures of transition metal compounds having a perovskite structure. Nanostructures of metal halide perovskites are particularly preferred. Nanoparticles and nanorods are preferred as such nanostructures.

[0105] In the light-emitting layer 113, as the organic compound (host material or the like) used in combination with the above-described light-emitting substance (guest material), one or more substances having an energy gap larger than the energy gap of the light-emitting substance (guest material) may be selected and used.

[0106] <Fluorescent Host Material> When the light-emitting substance used in the light-emitting layer 113 is a fluorescent substance, it is preferable to use, as an organic compound (host material) to be combined, an organic compound having a high energy level in a singlet excited state and a low energy level in a triplet excited state, or an organic compound having a high fluorescence quantum yield. Therefore, as long as an organic compound satisfies these conditions, a hole-transporting material (described above) or an electron-transporting material (described below) shown in this embodiment can be used.

[0107] Although some of the examples overlap with those described above, examples of the organic compound (host material) from the viewpoint of a preferable combination with the light-emitting substance (fluorescent light-emitting substance) include condensed polycyclic aromatic compounds such as anthracene derivatives, tetracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives.

[0108] Specific examples of organic compounds (host materials) that are preferably used in combination with fluorescent materials include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenylanthracene (abbreviation: DPAnth), and N,N-diphenylanthracene (abbreviation: DPAnth). N-nyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), YGAPA, PCAPA, N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazole-3-amine (abbreviation: PCAPBA), N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene, N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzyl benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)-biphenyl-4'-yl}-anthracene (abbreviation: FLPPA), 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 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), 9,9'-bianthryl (abbreviation: BANT), 9,9'-(stilbene-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-tri(1-pyrenyl)benzene (abbreviation: TPB3), 5,12-diphenyltetracene, 5,12-bis(biphenyl-2-yl)tetracene, etc.

[0109] <Phosphorescent Host Material> When the light-emitting substance used in the light-emitting layer 113 is a phosphorescent substance, an organic compound having a higher triplet excitation energy (energy difference between the ground state and the triplet excited state) than the triplet excitation energy of the light-emitting substance may be selected as the organic compound (host material) to be combined. When a plurality of organic compounds (for example, a first host material and a second host material (also referred to as an assist material)) are used in combination with the light-emitting substance to form an exciplex, it is preferable to mix these plurality of organic compounds with the phosphorescent substance.

[0110] With this structure, light emission can be efficiently obtained using Exciplex-Triple Energy Transfer (ExTET), which is energy transfer from an exciplex to a light-emitting substance. It is preferable to combine a plurality of organic compounds that easily form an exciplex, and it is particularly preferable to combine a compound that easily accepts holes (hole transport material) with a compound that easily accepts electrons (electron transport material).

[0111] Although some of the organic compounds (host materials and assist materials) overlap with the above-mentioned specific examples, from the viewpoint of a preferable combination with the light-emitting substance (phosphorescent light-emitting substance), examples of the organic compounds include aromatic amines (organic compounds having an aromatic amine skeleton), carbazole derivatives (organic compounds having a carbazole skeleton), dibenzothiophene derivatives (organic compounds having a dibenzothiophene skeleton), dibenzofuran derivatives (organic compounds having a dibenzofuran skeleton), oxadiazole derivatives (organic compounds having an oxadiazole skeleton), triazole derivatives (organic compounds having a triazole skeleton), and benzimidazole derivatives (organic compounds having a benzimidazole skeleton). compounds having a quinoxaline skeleton), quinoxaline derivatives (organic compounds having a quinoxaline skeleton), dibenzoquinoxaline derivatives (organic compounds having a dibenzoquinoxaline skeleton), quinazoline derivatives (organic compounds having a quinazoline skeleton), pyrimidine derivatives (organic compounds having a pyrimidine skeleton), triazine derivatives (organic compounds having a triazine skeleton), pyridine derivatives (organic compounds having a pyridine skeleton), bipyridine derivatives (organic compounds having a bipyridine skeleton), phenanthroline derivatives (organic compounds having a phenanthroline skeleton), furodiazine derivatives (organic compounds having a furodiazine skeleton), zinc- or aluminum-based metal complexes, and the like.

[0112] Among the organic compounds, specific examples of the aromatic amine and carbazole derivative, which are organic compounds with high hole-transporting properties, are the same as the specific examples of the hole-transporting material described above, and any of these is preferable as the host material.

[0113] Specific examples of the dibenzothiophene derivatives and dibenzofuran derivatives, which are organic compounds with high hole transport properties among the above organic compounds, include 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), DBT3P-II, 2,8-dipheny Examples of such compounds include 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II), all of which are preferable as the host material.

[0114] Other preferred host materials include metal complexes having an oxazole-based or thiazole-based ligand, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ).

[0115] Specific examples of the organic compounds having high electron transport properties, such as oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, quinazoline derivatives, and phenanthroline derivatives, among the above organic compounds, include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: OXD-9), 9-(4-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene ... -[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 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), 4 ,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOS), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2-(1,3-phenylene)bis[9-phenyl-1,10-phenanthroline] (abbreviation: mPPhen2P), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTP DBq-II), 2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3′-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,Examples include 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-{4-[9,10-di(2-naphthyl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviation: ZADN), and 2-[4′-(9-phenyl-9H-carbazol-3-yl)-3,1′-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), all of which are preferred as host materials.

[0116] Specific examples of the pyridine derivatives, diazine derivatives (including pyrimidine derivatives, pyrazine derivatives, and pyridazine derivatives), triazine derivatives, and furodiazine derivatives, which are organic compounds with high electron transport properties among the above organic compounds, include 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), and 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II). 4,6mCzP2Pm), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3 -(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d ]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[(3'-dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 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-[(1,1'-biphenyl)-4-yl]-4-phenyl-6-[9,9'-spirobi(9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H- Examples include carbazole (abbreviation: PCDBfTzn), 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), 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl)-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), and 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(1,1'-biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), all of which are preferred as host materials.

[0117] Specific examples of metal complexes, which are organic compounds with high electron transport properties among the above organic compounds, include zinc or aluminum metal complexes such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq) and tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq). ３ ), 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), as well as metal complexes having a quinoline skeleton or a benzoquinoline skeleton, all of which are preferable as the host material.

[0118] Other preferred host materials include polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)] (abbreviation: PF-BPy).

[0119] Furthermore, bipolar 9-phenyl-9′-(4-phenyl-2-quinazolinyl)-3,3′-bi-9H-carbazole (abbreviation: PCCzQz), 2-[4′-(9-phenyl-9H-carbazole-3-yl)-3,1′-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H, and the like, which are organic compounds having high hole-transporting properties and high electron-transporting properties, are also disclosed. Indole-11-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 11-(4-[1,1′-diphenyl]-4-yl-6-phenyl-1,3,5-triazin-2-yl)-11,12-dihydro-12-phenyl-indolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), or the like can also be used as the host material.

[0120] <Electron Transport Layer> The electron transport layer 114 is a layer that transports electrons injected from the second electrode 102 by the electron injection layer 115 described later to the light-emitting layer 113. The electron transport layer 114 is a layer containing an electron transporting material. The electron transporting material used for the electron transport layer 114 has an electron mobility of 1×10 or less when the square root of the electric field strength [V / cm] is 600. −６ cm ２A substance having an electron mobility of 1 / Vs or higher is preferred. Note that any substance having a higher electron-transporting property than a hole-transporting property can be used. Although the electron-transporting layer 114 functions as a single layer, in one embodiment of the present invention, it is preferable that the electron-transporting layer 114 has a stacked structure of two or more layers. Note that when the electron-transporting layer 114 has a stacked structure, as described in Embodiment 1, an electron-transporting layer containing a heteroaromatic compound and an organic compound or multiple types of heteroaromatic compounds (preferably a mixed film) has higher heat resistance than an electron-transporting layer having a different structure. Therefore, by performing a photolithography process on the electron-transporting layer containing a heteroaromatic compound and an organic compound or multiple types of heteroaromatic compounds, the influence of a thermal process on device characteristics can be suppressed.

[0121] <Electron Transporting Material> As the electron transporting material that can be used for the electron transporting layer 114, a heteroaromatic compound, which is an organic compound with high electron transporting properties, can be used. A heteroaromatic compound is a cyclic compound containing at least two different elements in a ring. The ring structure includes a three-membered ring, a four-membered ring, a five-membered ring, a six-membered ring, etc., but a five-membered ring or a six-membered ring is particularly preferred. The element contained therein is preferably a heteroaromatic compound containing one or more of nitrogen, oxygen, sulfur, and the like in addition to carbon. In particular, a heteroaromatic compound containing nitrogen (nitrogen-containing heteroaromatic compound) is preferred, and it is preferable to use a material with high electron transporting properties (electron transporting material) such as a nitrogen-containing heteroaromatic compound or a π-electron-deficient heteroaromatic compound containing the same.

[0122] The heteroaromatic compound is a heteroaromatic compound that is included in organic compounds and has at least one heteroaromatic ring.

[0123] The heteroaromatic ring has any one of a pyridine skeleton, a diazine skeleton, a triazine skeleton, and a polyazole skeleton.

[0124] The heteroaromatic ring also includes a condensed heteroaromatic ring having a condensed ring structure.

[0125] Examples of the fused heteroaromatic ring include a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a dibenzoquinazoline ring, a phenanthroline ring, a phlodiazin ring, and a benzimidazole ring.

[0126] Examples of heteroaromatic compounds include heteroaromatic compounds containing one or more of nitrogen, oxygen, and sulfur in addition to carbon, and examples of heteroaromatic compounds having a five-membered ring structure include organic compounds having an imidazole skeleton, organic compounds having a triazole skeleton, organic compounds having an oxazole skeleton, organic compounds having an oxadiazole skeleton, organic compounds having a thiazole skeleton, and organic compounds having a benzimidazole skeleton.

[0127] Furthermore, among heteroaromatic compounds containing one or more of nitrogen, oxygen, and sulfur in addition to carbon, examples of heteroaromatic compounds having a six-membered ring structure include organic compounds having a heteroaromatic ring such as a pyridine skeleton, a diazine skeleton (including a pyrimidine skeleton, a pyrazine skeleton, and a pyridazine skeleton), a triazine skeleton, and a polyazole skeleton. Examples of organic compounds having a structure in which pyridine skeletons are linked include organic compounds having a bipyridine structure and organic compounds having a terpyridine structure.

[0128] Furthermore, examples of heteroaromatic compounds having a fused ring structure partially containing the above-mentioned 6-membered ring structure include organic compounds having a fused heteroaromatic ring such as a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a phenanthroline ring, a furodiazine ring (containing a skeleton in which an aromatic ring is fused to a furan ring of a furodiazine skeleton), and a benzimidazole ring.

[0129] Specific examples of the heteroaromatic compound having a five-membered ring structure (such as an imidazole skeleton, a triazole skeleton, an oxazole skeleton, an oxadiazole skeleton, a thiazole skeleton, or a benzimidazole skeleton) include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl- Examples thereof include 5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 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).

[0130] Specific examples of the heteroaromatic compound having a 6-membered ring structure (pyridine skeleton, diazine skeleton (including pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton, etc.), triazine skeleton, polyazole skeleton, etc.) include 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 2-{4 -[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmP yPB), 4,6mCzBP2Pm, mFBPTzn, 8BP-4mDBtPBfpm, 9mDBtBPNfpr, 9pmDBtBPNfpr, 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-[(1,1'-biphenyl)-4-yl ]-4-phenyl-6-[9,9'-spirobi(9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothiophenyl]-2-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 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), 6-(1,1′-biphenyl-3-yl)-4-[3,5-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 the like.

[0131] Further, 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 4-[3-(dibenzothiophen-4-yl)phenyl]-8-(naphthalen-2-yl)-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8βN-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]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 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), and the like.

[0132] Other examples include 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), and 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6m BP-4Cz2PPm), 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviation: TmPPPyTz), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl)-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), and the like.

[0133] Specific examples of the heteroaromatic compound having a fused ring structure partially containing a 6-membered ring structure include bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2-(1,3-phenylene)bis[9-phenyl-1,10-phenanthroline] (abbreviation: mPPhen2P), 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: 2mDBTPDBq-II), and 2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline. phosphorus (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2mpPCBPDBq, and the like.

[0134] In addition to the heteroaromatic compounds described above, the electron transport layer may also include the following metal complexes: tris(8-quinolinolato)aluminum(III) (abbreviation: Alq ３ ), Almq ３ , 8-quinolinolato-lithium(I) (abbreviation: Liq), BeBq ２ metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq) and bis(8-quinolinolato)zinc(II) (abbreviation: Znq); and metal complexes having an oxazole skeleton or a thiazole skeleton, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ).

[0135] Furthermore, polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)] (abbreviation: PF-BPy) can also be used as the electron transport material.

[0136] <Electron Injection Layer> The electron injection layer 115 is a layer containing a substance with high electron injection properties. The electron injection layer 115 is a layer for increasing the efficiency of electron injection from the second electrode 102, and it is preferable to use a material having a small difference (0.5 eV or less) between the work function value of the material used for the second electrode 102 and the LUMO level value of the material used for the electron injection layer 115. Therefore, the electron injection layer 115 is preferably made of lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ２ ), 8-(quinolinolato)lithium (abbreviation: Liq), 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), lithium oxide (LiO ｘ ), alkali metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used. Also, erbium fluoride (ErF ３ A rare earth metal compound such as ytterbium (Yb) or ytterbium (Yb) can be used. Furthermore, an electride can be used for the electron injection layer 115. For example, an electride can be a substance in which a mixed oxide of calcium and aluminum is doped with electrons at a high concentration. Note that the above-mentioned substance constituting the electron transport layer 114 can also be used.

[0137] The electron-injection layer 115 may also be formed using a composite material obtained by mixing an organic compound and an electron donor (donor). Such composite materials have excellent electron-injection and electron-transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent at transporting the generated electrons. Specifically, the electron-transporting materials (metal complexes, heteroaromatic compounds, etc.) used in the electron-transport layer 114 described above can be used. The electron donor may be any substance that exhibits electron-donating properties to the organic compound. Specifically, alkali metals, alkaline earth metals, or rare earth metals are preferred, such as lithium, cesium, magnesium, calcium, erbium, and ytterbium. Alkali metal oxides or alkaline earth metal oxides are preferred, such as lithium oxide, calcium oxide, and barium oxide. Lewis bases such as magnesium oxide can also be used. Organic compounds such as tetrathiafulvalene (abbreviation: TTF) can also be used. A plurality of these materials may also be stacked.

[0138] Alternatively, a composite material obtained by mixing an organic compound and a metal may be used for the electron-injection layer 115. Note that the organic compound used here preferably has a LUMO level of −3.6 eV or more and −2.3 eV or less. In addition, a material having an unshared electron pair is preferable.

[0139] Therefore, the organic compound used in the composite material may be a composite material obtained by mixing a heteroaromatic compound with a metal, as described above as being usable in the electron transport layer. Preferred heteroaromatic compounds include heteroaromatic compounds having a five-membered ring structure (such as an imidazole skeleton, a triazole skeleton, an oxazole skeleton, an oxadiazole skeleton, a thiazole skeleton, or a benzimidazole skeleton), heteroaromatic compounds having a six-membered ring structure (such as a pyridine skeleton, a diazine skeleton (including a pyrimidine skeleton, a pyrazine skeleton, or a pyridazine skeleton), a triazine skeleton, a bipyridine skeleton, or a terpyridine skeleton), and heteroaromatic compounds having a fused ring structure partially including a six-membered ring structure (such as a quinoline skeleton, a benzoquinoline skeleton, a quinoxaline skeleton, a dibenzoquinoxaline skeleton, or a phenanthroline skeleton). Specific materials are described above, and therefore will not be described here.

[0140] The metal used in the composite material is preferably a transition metal belonging to Group 5, 7, 9, or 11 in the periodic table, or a material belonging to Group 13, such as Ag, Cu, Al, or In. In this case, the organic compound forms a Singly Occupied Molecular Orbital (SOMO) with the transition metal.

[0141] <Substrate> The light-emitting device described in this embodiment can be formed on various substrates. Note that the type of substrate is not limited to a specific one. Examples of the substrate include a semiconductor substrate (for example, a single crystal substrate or a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate having stainless steel foil, a tungsten substrate, a substrate having tungsten foil, a flexible substrate, a laminated film, paper containing a fibrous material, or a base film.

[0142] Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, soda lime glass, etc. Examples of flexible substrates, laminated films, base films, etc. include plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethersulfone (PES), synthetic resins such as acrylic, polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, polyamide, polyimide, aramid, epoxy, inorganic vapor deposition films, and papers.

[0143] The light-emitting device described in this embodiment can be fabricated by a vacuum process such as vapor deposition, a spin coating method, or a solution process such as an inkjet method. When a vapor deposition method is used, a physical vapor deposition (PVD) method such as sputtering, ion plating, ion beam deposition, molecular beam deposition, or vacuum deposition, or a chemical vapor deposition (CVD) method can be used. In particular, layers having various functions included in the EL layer of the light-emitting device (hole injection layer 111, hole transport layer 112, light-emitting layer 113, electron transport layer 114, and electron injection layer 115) can be formed by a vapor deposition method (vacuum deposition, etc.), a coating method (dip coating, die coating, bar coating, spin coating, spray coating, etc.), a printing method (inkjet printing, screen (stencil printing), offset (lithographic printing), flexography (relief printing), gravure printing, microcontact printing, etc.), or the like.

[0144] When applying the above-mentioned coating method, printing method, or other film formation method, it is possible to use high molecular weight compounds (oligomers, dendrimers, polymers, etc.), medium molecular weight compounds (compounds in the intermediate range between low molecular weight and high molecular weight: molecular weight 400 to 4000), inorganic compounds (quantum dot materials, etc.), etc. As the quantum dot material, it is possible to use colloidal quantum dot materials, alloy-type quantum dot materials, core-shell type quantum dot materials, core-type quantum dot materials, etc.

[0145] The materials for the layers (hole injection layer 111, hole transport layer 112, light-emitting layer 113, electron transport layer 114, and electron injection layer 115) constituting the EL layer 103 of the light-emitting device described in this embodiment mode are not limited to those described in this embodiment mode, and other materials can be used in combination as long as they can fulfill the functions of the respective layers.

[0146] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0147] Embodiment 3 In this embodiment, a specific structural example of a light-emitting device (also referred to as a display panel) which is one embodiment of the present invention and a manufacturing method thereof will be described.

[0148] <Configuration Example 1 of Light-Emitting Device 700> The light-emitting device 700 shown in FIG. 3A includes a light-emitting device 550B, a light-emitting device 550G, a light-emitting device 550R, and a partition wall 528. The light-emitting device 550B, the light-emitting device 550G, the light-emitting device 550R, and the partition wall 528 are formed on a functional layer 520 provided on a first substrate 510. The functional layer 520 includes a driving circuit GD and a driving circuit SD, each of which is composed of a plurality of transistors, as well as wiring and the like that electrically connects these components. Note that, as an example, these driving circuits are electrically connected to and can drive the light-emitting device 550B, the light-emitting device 550G, and the light-emitting device 550R. The light-emitting device 700 also includes an insulating layer 705 on the functional layer 520 and each light-emitting device. The insulating layer 705 functions to bond the second substrate 770 and the functional layer 520 together. The driving circuit GD and the driving circuit SD will be described later in embodiment 4.

[0149] Note that the light-emitting devices 550B, 550G, and 550R have the device structure shown in Embodiment 2. That is, the EL layer 103 in the structure shown in FIG.

[0150] In this specification and the like, a structure in which different light-emitting layers are formed for light-emitting devices of each color (e.g., blue (B), green (G), and red (R)) or different light-emitting layers are painted may be referred to as an SBS (Side By Side) structure. In the light-emitting device 700 shown in FIG. 3A , the light-emitting device 550B, the light-emitting device 550G, and the light-emitting device 550R are arranged in this order, but one embodiment of the present invention is not limited to this configuration. For example, in the light-emitting device 700, these light-emitting devices may be arranged in the order of the light-emitting device 550B, the light-emitting device 550R, and the light-emitting device 550G.

[0151] As shown in FIG. 3A , light-emitting device 550B includes electrode 551B, electrode 552, and EL layer 103B. The specific configuration of each layer is as described in Embodiment 2. EL layer 103B has a stacked structure including multiple layers with different functions, including a light-emitting layer. While FIG. 3A illustrates only the hole injection / transport layer 104B, first electron transport layer 108B-1, second electron transport layer 108B-2, and electron injection layer 109 among the layers included in EL layer 103B, including the light-emitting layer, the present invention is not limited thereto. Hole injection / transport layer 104B represents a layer having the functions of the hole injection layer and hole transport layer described in Embodiment 2 and may have a stacked structure. Throughout this specification, the term "hole injection / transport layer" can be interpreted in this manner in any light-emitting device.

[0152] The electron transport layer has a stacked structure including at least a first electron transport layer 108B-1 and a second electron transport layer 108B-2. The electron transport layer in contact with the light-emitting layer is referred to as the first electron transport layer 108B-1, and the electron transport layer in contact with the electron injection layer 109 is referred to as the second electron transport layer 108B-2. As described in Embodiment 1, the second electron transport layer 108B-2 is a layer (preferably a layer made of a mixed film) containing a heteroaromatic compound and an organic compound or multiple types of heteroaromatic compounds. The second electron transport layer 108B-2 may be formed using an electron-transporting material. It may be a layer formed using one type of heteroaromatic compound or an organic compound, or a layer containing an organic compound and a heteroaromatic compound, or multiple types of heteroaromatic compounds. The first electron transport layer 108B-1 may have a function of blocking holes moving from the anode side through the light-emitting layer to the cathode side. The electron injection layer 109 may also have a stacked structure in which a part or the whole of the layer is formed using different materials.

[0153] 1C , among the layers included in the EL layer 103 including the light-emitting layer, an insulating layer 107 may be formed on the side surfaces (or edges) of the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2. When the insulating layer 107 is added to the light-emitting device configuration of FIG. 3A , the insulating layer 107 is formed on the electrode 551B while leaving a sacrificial layer formed on a portion of the EL layer 103B (in this embodiment, the first electron transport layer 108B-1 and the second electron transport layer 108B-2 are formed on the light-emitting layer) during the manufacturing process, and the sacrificial layer is then removed. Therefore, the insulating layer 107B is formed in contact with the side surfaces (or edges) of the portion (mentioned above) of the EL layer 103B. This can prevent oxygen, moisture, or their constituent elements from penetrating into the interior of the EL layer 103B from the side surfaces. The insulating layer 107B can be formed using, for example, aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon nitride, silicon nitride oxide, etc. The insulating layer 107B can be formed by a sputtering method, a CVD method, an MBE method, a PLD method, an ALD method, etc., but the ALD method, which has good coverage, is more preferable.

[0154] Furthermore, the electron injection layer 109 is formed to cover a part of the EL layer 103B (including the light-emitting layer, the hole injection / transport layer 104B, the first electron transport layer 108B-1, and the second electron transport layer 108B-2) (however, when the insulating layer 107B is formed, this refers to "a part of the EL layer 103B (including the light-emitting layer, the hole injection / transport layer 104B, the first electron transport layer 108B-1, and the second electron transport layer 108B-2) and the insulating layer 107B"). The electron injection layer 109 may have a stacked structure of two or more layers having different electrical resistances within the layers. For example, a first layer in contact with the second electron transport layer 108B-2 may be formed only from an electron transport material, and a second layer formed using an electron transport material containing a metal material may be stacked thereon, or a third layer formed using an electron transport material containing a metal material may be provided between the first layer and the second electron transport layer 108B-2.

[0155] The electrode 552 is formed on the electron injection layer 109. The electrode 551B and the electrode 552 overlap each other in a region. The EL layer 103B is provided between the electrode 551B and the electrode 552. Therefore, the electrode 552 is in contact with a side surface (or an end portion) of a part of the EL layer 103B (including the light-emitting layer, the hole injection / transport layer 104B, the first electron transport layer 108B-1, and the second electron transport layer 108B-2) via the electron injection layer 109. This prevents an electrical short circuit between the part of the EL layer 103B (including the light-emitting layer, the hole injection / transport layer 104B, the first electron transport layer 108B-1, and the second electron transport layer 108B-2) and the electrode 552, more specifically, between the hole injection / transport layer 104B of the EL layer 103B and the electrode 552.

[0156] 3A has a structure similar to that of the EL layer 103 described in Embodiment 2. The EL layer 103B can emit, for example, blue light.

[0157] As shown in FIG. 3A , the light-emitting device 550G includes an electrode 551G, an electrode 552, and an EL layer 103G. The specific configuration of each layer is as described in Embodiment 2. The EL layer 103G has a stacked structure including a plurality of layers with different functions, including a light-emitting layer. Of the layers included in the EL layer 103G including the light-emitting layer, FIG. 3A illustrates only the hole injection / transport layer 104G, the first electron transport layer 108G-1, the second electron transport layer 108G-2, and the electron injection layer 109. However, the present invention is not limited to this. The hole injection / transport layer 104G represents a layer having the functions of the hole injection layer and the hole transport layer described in Embodiment 2, and may have a stacked structure.

[0158] The electron transport layer has a stacked structure including at least a first electron transport layer 108G-1 and a second electron transport layer 108G-2. The electron transport layer in contact with the light-emitting layer is referred to as the first electron transport layer 108G-1, and the electron transport layer in contact with the electron injection layer 109 is referred to as the second electron transport layer 108G-2. As described in Embodiment 1, the second electron transport layer 108G-2 is a layer (preferably a layer formed of a mixed film) containing a heteroaromatic compound and an organic compound or multiple types of heteroaromatic compounds. The second electron transport layer 108G-2 may be formed using an electron-transporting material. It may be a layer formed using one type of heteroaromatic compound or an organic compound, or a layer containing an organic compound and a heteroaromatic compound, or multiple types of heteroaromatic compounds. The first electron transport layer 108G-1 may have a function of blocking holes that move from the anode side through the light-emitting layer to the cathode side. The electron injection layer 109 may also have a stacked structure in which a part or the whole of the layer is formed using different materials.

[0159] 1C , an insulating layer 107 may be formed on the side surfaces (or edges) of the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2, which are layers included in the EL layer 103 including the light-emitting layer. When the insulating layer 107 is added to the light-emitting device configuration of FIG. 3A , the insulating layer 107 is formed on the electrode 551G while leaving a sacrificial layer formed on a portion of the EL layer 103G (in this embodiment, the first electron transport layer 108G-1 and the second electron transport layer 108G-2 are formed on the light-emitting layer) during the manufacturing process, and the sacrificial layer is then removed. Therefore, the insulating layer 107G is formed in contact with the side surfaces (or edges) of the portion (above) of the EL layer 103G. This prevents oxygen, moisture, or their constituent elements from penetrating the EL layer 103G from the side surfaces. The insulating layer 107G can be formed using, for example, aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon nitride, silicon nitride oxide, etc. The insulating layer 107G can be formed by a sputtering method, a CVD method, an MBE method, a PLD method, an ALD method, or the like, but the ALD method is more preferable because of its good coverage.

[0160] Furthermore, the electron injection layer 109 is formed to cover a portion of the EL layer 103G (including the light-emitting layer, the hole injection / transport layer 104G, the first electron transport layer 108G-1, and the second electron transport layer 108G-2) (however, when the insulating layer 107G is formed, "a portion of the EL layer 103G (including the light-emitting layer, the hole injection / transport layer 104G, the first electron transport layer 108G-1, and the second electron transport layer 108G-2) and the insulating layer 107G"). The electron injection layer 109 may have a stacked structure of two or more layers with different electrical resistances within the layers. For example, a first layer in contact with the second electron transport layer 108G-2 may be formed only from an electron transport material, and a second layer formed thereon using an electron transport material containing a metal material may be stacked thereon. Alternatively, a third layer formed from an electron transport material containing a metal material may be provided between the first layer and the second electron transport layer 108G-2.

[0161] The electrode 552 is formed on the electron injection layer 109. The electrode 551G and the electrode 552 overlap each other in a region. The EL layer 103G is provided between the electrode 551G and the electrode 552. Therefore, the electrode 552 is in contact with a side surface (or an end portion) of a portion of the EL layer 103G (including the light-emitting layer, the hole injection / transport layer 104G, the first electron transport layer 108G-1, and the second electron transport layer 108G-2) via the electron injection layer 109. This prevents an electrical short circuit between the portion of the EL layer 103G (including the light-emitting layer, the hole injection / transport layer 104G, the first electron transport layer 108G-1, and the second electron transport layer 108G-2) and the electrode 552, more specifically, between the hole injection / transport layer 104G and the electrode 552 of the EL layer 103G.

[0162] 3A has the same structure as the EL layer 103 described in Embodiment 2. The EL layer 103G can emit, for example, green light.

[0163] As shown in FIG. 3A , the light-emitting device 550R includes an electrode 551R, an electrode 552, and an EL layer 103R. The specific configuration of each layer is as described in Embodiment 2. The EL layer 103R has a stacked structure including a plurality of layers with different functions, including a light-emitting layer. Of the layers included in the EL layer 103R, including the light-emitting layer, only the hole injection / transport layer 104R, the first electron transport layer 108R-1, the second electron transport layer 108R-2, and the electron injection layer 109 are shown in FIG. 3A , but the present invention is not limited thereto. The hole injection / transport layer 104R represents a layer having the functions of the hole injection layer and the hole transport layer described in Embodiment 2, and may have a stacked structure.

[0164] The electron transport layer has a stacked structure including at least a first electron transport layer 108R-1 and a second electron transport layer 108R-2. The electron transport layer in contact with the light-emitting layer is referred to as the first electron transport layer 108R-1, and the electron transport layer in contact with the electron injection layer 109 is referred to as the second electron transport layer 108R-2. As described in Embodiment 1, the second electron transport layer 108R-2 is a layer (preferably a layer formed of a mixed film) containing a heteroaromatic compound and an organic compound or multiple types of heteroaromatic compounds. The second electron transport layer 108R-2 may be formed using an electron-transporting material. It may be a layer formed using one type of heteroaromatic compound or an organic compound, or a layer containing an organic compound and a heteroaromatic compound, or multiple types of heteroaromatic compounds. The first electron transport layer 108R-1 may have a function of blocking holes that move from the anode side through the light-emitting layer to the cathode side. The electron injection layer 109 may also have a stacked structure in which a part or the whole of the layer is formed using different materials.

[0165] 1C , an insulating layer 107 may be formed on the side surfaces (or edges) of the hole injection / transport layer 104, the light-emitting layer 113, the first electron transport layer 108-1, and the second electron transport layer 108-2, which are layers included in the EL layer 103 including the light-emitting layer. When the insulating layer 107 is added to the light-emitting device configuration of FIG. 3A , the insulating layer 107 is formed on the electrode 551R while leaving a sacrificial layer formed on a portion of the EL layer 103R (in this embodiment, the first electron transport layer 108R-1 and the second electron transport layer 108R-2 are formed on the light-emitting layer), and then the sacrificial layer is removed. Therefore, the insulating layer 107R is formed in contact with the side surfaces (or edges) of the portion (above) of the EL layer 103R. This prevents oxygen, moisture, or their constituent elements from penetrating the EL layer 103R from the side surfaces. The insulating layer 107R can be formed using, for example, aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon nitride, silicon nitride oxide, etc. The insulating layer 107R can be formed by a sputtering method, a CVD method, an MBE method, a PLD method, an ALD method, etc., but the ALD method, which has good coverage, is more preferable.

[0166] Furthermore, the electron injection layer 109 is formed to cover a portion of the EL layer 103R (including the light-emitting layer, the hole injection / transport layer 104R, the first electron transport layer 108R-1, and the second electron transport layer 108R-2) (however, when the insulating layer 107R is formed, "a portion of the EL layer 103R (including the light-emitting layer, the hole injection / transport layer 104R, the first electron transport layer 108R-1, and the second electron transport layer 108R-2) and the insulating layer 107R"). The electron injection layer 109 may have a stacked structure of two or more layers with different electrical resistances within the layers. For example, a first layer in contact with the second electron transport layer 108R-2 may be formed only from an electron transport material, and a second layer formed using an electron transport material containing a metal material may be stacked thereon. Alternatively, a third layer formed using an electron transport material containing a metal material may be provided between the first layer and the second electron transport layer 108R-2.

[0167] The electrode 552 is formed on the electron injection layer 109. The electrode 551R and the electrode 552 overlap each other in a region. The EL layer 103R is provided between the electrode 551R and the electrode 552. Therefore, the electrode 552 is in contact with a side surface (or an end portion) of a portion of the EL layer 103R (including the light-emitting layer, the hole injection / transport layer 104R, the first electron transport layer 108R-1, and the second electron transport layer 108R-2) via the electron injection layer 109. This prevents an electrical short circuit between the portion of the EL layer 103R (including the light-emitting layer, the hole injection / transport layer 104R, the first electron transport layer 108R-1, and the second electron transport layer 108R-2) and the electrode 552, more specifically, between the hole injection / transport layer 104R of the EL layer 103R and the electrode 552.

[0168] 3A has the same structure as the EL layer 103 described in Embodiment 2. The EL layer 103R can emit, for example, red light.

[0169] A gap 580 is provided between each of the EL layers 103B, 103G, and 103R. In each EL layer, the hole injection layer included in the hole transport region located between the anode and the light-emitting layer, in particular, often has high conductivity, and therefore may cause crosstalk if formed as a layer common to adjacent light-emitting devices. Therefore, by providing a gap 580 between each EL layer as shown in this configuration example, it is possible to suppress the occurrence of crosstalk between adjacent light-emitting devices.

[0170] In a high-resolution light-emitting device (display panel) exceeding 1000 ppi, if electrical conduction is found between EL layer 103B, EL layer 103G, and EL layer 103R, crosstalk occurs, narrowing the color gamut that can be displayed by the light-emitting device. By providing gap 580 in a high-resolution display panel exceeding 1000 ppi, preferably a high-resolution display panel exceeding 2000 ppi, and more preferably an ultra-high-resolution display panel exceeding 5000 ppi, it is possible to provide a display panel that can display vivid colors.

[0171] As shown in Fig. 3B, the partition wall 528 has openings 528B, 528G, and 528R. As shown in Fig. 3A, the opening 528B overlaps with the electrode 551B, the opening 528G overlaps with the electrode 551G, and the opening 528R overlaps with the electrode 551R. Fig. 3B is a top view in the X-Y direction of the light-emitting device 700 shown in Fig. 3A, and the cross-sectional view taken along line Y1-Y2 shown in Fig. 3B corresponds to Fig. 3A.

[0172] In addition, since pattern formation using photolithography is performed in the separation process of these EL layers (EL layer 103B, EL layer 103G, and EL layer 103R), a high-definition light-emitting device (display panel) can be manufactured. Furthermore, the edges (side surfaces) of the EL layers processed by pattern formation using photolithography have a shape that has approximately the same surface (or is located on approximately the same plane). Furthermore, in this case, the gap 580 provided between each EL layer is preferably 5 μm or less, and more preferably 1 μm or less.

[0173] In the EL layer, the hole injection layer included in the hole transport region located between the anode and the light-emitting layer, in particular, often has high conductivity, and therefore, if it is formed as a layer common to adjacent light-emitting devices, it may cause crosstalk. Therefore, by separating the EL layer by pattern formation using photolithography as shown in this configuration example, it is possible to suppress the occurrence of crosstalk between adjacent light-emitting devices.

[0174] 4A, an electrode 551B, an electrode 551G, and an electrode 551R are formed. For example, a conductive film is formed on the functional layer 520 formed on the first substrate 510, and is processed into a predetermined shape by photolithography.

[0175] The conductive film can be formed by sputtering, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), vacuum evaporation, pulsed laser deposition (PLD), atomic layer deposition (ALD), or the like. CVD methods include plasma enhanced chemical vapor deposition (PECVD) and thermal CVD. One type of thermal CVD method is metal organic chemical vapor deposition (MOCVD).

[0176] In addition to the photolithography method described above, the conductive film may be processed by a nanoimprint method, a sandblasting method, a lift-off method, or the like. Furthermore, an island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask. Here, "island-shaped" refers to a state in which the thin film is separated in plan view from a layer made of the same material and formed in the same process.

[0177] There are two typical photolithography methods. One is a method in which a resist mask is formed on a thin film to be processed, the thin film is processed by etching or the like, and the resist mask is then removed. The other is a method in which a photosensitive thin film is formed, and then the thin film is processed into a desired shape by exposure and development. Note that the former method includes heat treatment steps such as pre-applied bake (PAB) after resist application and post-exposure bake (PEB) after exposure. In one embodiment of the present invention, photolithography is used not only for processing a conductive film but also for processing a thin film (a film made of an organic compound or a film partially containing an organic compound) used to form an EL layer.

[0178] In photolithography, the light used for exposure can 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 can also be performed by immersion exposure technology. Extreme ultraviolet (EUV) light or X-rays can also be used as the light used for exposure. An electron beam can also be used instead of light used 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.

[0179] For etching the thin film using a resist mask, dry etching, wet etching, sandblasting, or the like can be used.

[0180] 4B , a partition wall 528 is formed between the electrode 551B, the electrode 551G, and the electrode 551R. For example, the partition wall 528 can be formed by forming an insulating film covering the electrode 551B, the electrode 551G, and the electrode 551R, forming openings by photolithography, and exposing parts of the electrode 551B, the electrode 551G, and the electrode 551R. Examples of materials that can be used for the partition wall 528 include inorganic materials, organic materials, and composite materials of inorganic and organic materials. Specifically, an inorganic oxide film, an inorganic nitride film, an inorganic oxynitride film, or the like, or a laminated material formed by stacking a plurality of films selected from these films, more specifically, a silicon oxide film, a film containing acrylic, a film containing polyimide, or the like, or a laminated material formed by stacking a plurality of films selected from these films, can be used.

[0181] Next, as shown in Fig. 5A, the EL layer 103B is formed on the electrode 551B, the electrode 551G, the electrode 551R, and the partition wall 528. Note that in Fig. 5A, the EL layer 103B includes the hole injection / transport layer 104B, the light-emitting layer, the first electron transport layer 108B-1, and the second electron transport layer 108B-2. For example, the EL layer 103B is formed on the electrode 551B, the electrode 551G, the electrode 551R, and the partition wall 528 so as to cover them by using a vacuum deposition method. Furthermore, a sacrificial layer 110 is formed on the EL layer 103B.

[0182] The sacrificial layer 110 can be a film that is highly resistant to the etching process of the EL layer 103B, i.e., a film with a large etching selectivity. The sacrificial layer 110 preferably has a stacked structure of a first sacrificial layer and a second sacrificial layer that have different etching selectivity. The sacrificial layer 110 can be a film that can be removed by wet etching, which causes little damage to the EL layer 103B. Oxalic acid or the like can be used as an etching material for wet etching. In this specification and the like, the sacrificial layer may also be referred to as a mask layer.

[0183] The sacrificial layer 110 may be, for example, a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic insulating film. The sacrificial layer 110 may be formed by various film formation methods such as sputtering, vapor deposition, CVD, and ALD.

[0184] For example, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metal materials can be used as the sacrificial layer 110. In particular, it is preferable to use a low-melting-point material such as aluminum or silver.

[0185] Furthermore, a metal oxide such as indium gallium zinc oxide (In—Ga—Zn oxide, also referred to as IGZO) can be used as the sacrificial layer 110. Furthermore, 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), indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide), etc. can also be used. Alternatively, indium tin oxide containing silicon can also be used.

[0186] It is also possible to use an oxide using 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) instead of the gallium. In particular, it is preferable that M is one or more elements selected from gallium, aluminum, and yttrium.

[0187] The sacrificial layer 110 can be made of an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide.

[0188] Furthermore, it is preferable to use a material for the sacrificial layer 110 that can be dissolved in a chemically stable solvent for at least the film (second electron transport layer 108B-2) located at the top of the EL layer 103B. In particular, a material that dissolves in water or alcohol can be suitably used for the sacrificial layer 110. When forming the sacrificial layer 110, it is preferable to apply the sacrificial layer 110 dissolved in a solvent such as water or alcohol by a wet film formation method, and then perform a heat treatment to evaporate the solvent. At this time, performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature in a short time, thereby reducing thermal damage to the EL layer 103B.

[0189] When the sacrificial layer 110 has a laminated structure, a layer made of the above-mentioned material can be used as a first sacrificial layer, and a second sacrificial layer can be formed underneath to form a laminated structure.

[0190] In this case, the second sacrificial layer is a film used as a hard mask when etching the first sacrificial layer. Furthermore, the first sacrificial layer is exposed when the second sacrificial layer is processed. Therefore, a combination of films with a high etching selectivity is selected for the first sacrificial layer and the second sacrificial layer. Therefore, a film that can be used for the second sacrificial layer can be selected depending on the etching conditions for the first sacrificial layer and the second sacrificial layer.

[0191] For example, when dry etching using a gas containing fluorine (also called a fluorine-based gas) is used to etch the second sacrificial layer, silicon, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum, tantalum nitride, an alloy containing molybdenum and niobium, an alloy containing molybdenum and tungsten, etc. can be used for the second sacrificial layer. Here, metal oxide films such as IGZO and ITO can be used as films that can have a large etching selectivity (i.e., can slow the etching rate) compared to dry etching using the fluorine-based gas, and these can be used for the first sacrificial layer.

[0192] However, the second sacrificial layer is not limited to this, and can be selected from various materials depending on the etching conditions of the first sacrificial layer and the second sacrificial layer, for example, from among the films that can be used for the first sacrificial layer.

[0193] The second sacrificial layer 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.

[0194] Alternatively, an oxide film can be used as the second sacrificial layer. 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.

[0195] Next, as shown in FIG. 5A , a resist mask REG is formed in a desired shape on the sacrificial layer 110 using photolithography. When performing such a method, heat treatment processes such as pre-applied bake (PAB) and post-exposure bake (PEB) are performed. For example, the PAB temperature is approximately 100° C., and the PEB temperature is approximately 120° C. Therefore, the light-emitting device must be able to withstand these treatment temperatures. In the light-emitting device according to one embodiment of the present invention, the layer exposed to the photolithography process is, specifically, the highly heat-resistant layer containing the heteroaromatic compound and the organic compound described in Embodiment 1. Therefore, the influence of the heat treatment is suppressed, and a light-emitting device having a highly reliable light-emitting device can be obtained.

[0196] 5B , the resulting resist mask REG is used to etch away the portion of the sacrificial layer 110 that is not covered by the resist mask REG, forming a sacrificial layer 110B, and then the resist mask REG is removed. Then, the portion of the EL layer 103B that is not covered by the sacrificial layer 110B is etched away, and the EL layer 103B on the electrode 551G and the EL layer 103B on the electrode 551R are etched away to form a shape with a side surface (or an exposed side surface) or a strip-like shape extending in a direction perpendicular to the drawing. Specifically, dry etching is performed using the sacrificial layer 110B patterned on the EL layer 103B that overlaps the electrode 551B. In addition, when the sacrificial layer 110B has a laminated structure of the first sacrificial layer and the second sacrificial layer, after etching a part of the second sacrificial layer with the resist mask REG, the resist mask REG may be removed, and then a part of the first sacrificial layer may be etched using the second sacrificial layer as a mask, thereby processing the EL layer 103B into a predetermined shape. In addition, the partition wall 528 may be used as an etching stopper.

[0197] Next, as shown in Fig. 5C , with the sacrificial layer 110B formed, an EL layer 103G is formed on the sacrificial layer 110B, the electrode 551G, the electrode 551R, and the partition wall 528. Note that in Fig. 5C , the EL layer 103G is formed up to the hole injection / transport layer 104G, the light-emitting layer, and the first electron transport layer 108G-1. For example, the EL layer 103G is formed on the electrode 551G, the electrode 551R, and the partition wall 528 so as to cover them using a vacuum deposition method. Furthermore, a sacrificial layer 110 is formed on the EL layer 103G.

[0198] Next, as shown in FIG. 6A , the EL layer 103G on the electrode 551G is processed into a predetermined shape. For example, a sacrificial layer is formed on the EL layer 103G, and a resist mask is formed in the desired shape on the EL layer 103G using photolithography. The portion of the sacrificial layer not covered by the resulting resist mask is then etched away to form a sacrificial layer 110G, and the resist mask is then removed. The portion of the EL layer 103G not covered by the sacrificial layer 110G is then etched away, and the EL layer 103G on the electrode 551B and the EL layer 103G on the electrode 551R are then etched away to form a shape with a side surface (or an exposed side surface) or a strip-like shape extending in a direction perpendicular to the drawing. Specifically, dry etching is performed using the sacrificial layer 110G patterned on the EL layer 103G overlapping the electrode 551G. In addition, when the sacrificial layer 110G has a stacked structure of the first sacrificial layer and the second sacrificial layer, after etching a part of the second sacrificial layer using a resist mask, the resist mask may be removed, and then a part of the first sacrificial layer may be etched using the second sacrificial layer as a mask, thereby processing the EL layer 103G into a predetermined shape. In addition, the partition wall 528 may be used as an etching stopper.

[0199] Next, as shown in FIG. 6B , a sacrificial layer 110B is formed on the second electron transport layer 108B-2, and a sacrificial layer 110G is formed on the electron transport layer 108G-2. Then, an EL layer 103R is formed on the sacrificial layer 110B, the sacrificial layer 110G, the electrode 551R, and the partition wall 528. In FIG. 6B , the EL layer 103R includes the hole injection / transport layer 104R, the light-emitting layer, the first electron transport layer 108R-1, and the second electron transport layer 108R-2. For example, the EL layer 103R is formed on the sacrificial layer 110B, the sacrificial layer 110G, the electrode 551R, and the partition wall 528 so as to cover them, using a vacuum deposition method. Subsequently, the EL layer 103R on the electrode 551R is processed into a predetermined shape. For example, a sacrificial layer is formed on the EL layer 103R, and then a resist is formed on the EL layer 103R in a desired shape using photolithography. The portion of the sacrificial layer that is not covered by the resulting resist mask is removed by etching, and the resist mask is removed to form the sacrificial layer 110R.

[0200] Next, the portion of the EL layer 103R not covered by the sacrificial layer 110R is removed by etching, and the EL layer 103R on the electrode 551B and the EL layer 103R on the electrode 551G are removed by etching to form a shape with lateral surfaces (or with exposed lateral surfaces) or a strip-like shape extending perpendicular to the drawing. Specifically, dry etching is performed using the sacrificial layer 110R patterned on the EL layer 103R overlapping the electrode 551R. Note that if the sacrificial layer 110R has a stacked structure of the first and second sacrificial layers, a portion of the second sacrificial layer may be etched using a resist mask, and then the resist mask may be removed. Then, a portion of the first sacrificial layer may be etched using the second sacrificial layer as a mask, thereby forming the EL layer 103R into a predetermined shape. Note that the partition wall 528 can be used as an etching stopper.

[0201] Next, as shown in FIG. 6C , while leaving the sacrificial layers (110B, 110G, 110R) on the EL layers (103B, 103G, 103R), an insulating layer 107 is formed on the sacrificial layers (110B, 110G, 110R) and the partition wall 528. The insulating layer 107 can be formed, for example, by an ALD method. In this case, the insulating layer 107 is formed in contact with the side surfaces of the EL layers (103B, 103G, 103R) as shown in FIG. 6C . This prevents oxygen, moisture, or their constituent elements from penetrating into the interior of the EL layers (103B, 103G, 103R) from the side surfaces. Examples of materials that can be used for the insulating layer 107 include aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon nitride, and silicon nitride oxide.

[0202] 7A , the sacrificial layers (110B, 110G, and 110R) are removed, and part of the insulating layer 107 is removed to form insulating layers (107B, 107G, and 107R), and then the electron injection layer 109 is formed. The electron injection layer 109 is formed by, for example, vacuum deposition. The electron injection layer 109 is formed on the second electron transport layers (108B-2, 108G-2, and 108R-2). The electron injection layer 109 has a structure in which it is in contact with the side surfaces (or end portions) of the EL layers (103B, 103G, 103R) (note that the EL layers (103B, 103G, 103R) shown in FIG. 7A include hole injection / transport layers (104R, 104G, 104B), a light-emitting layer, first electron transport layers (108B-1, 108G-1, 108R-1), and second electron transport layers (108B-2, 108G-2, 108R-2)) via the insulating layer 107.

[0203] Next, as shown in FIG. 7B , an electrode 552 is formed. The electrode 552 is formed by, for example, vacuum evaporation. The electrode 552 is formed on the electron injection layer 109. The electrode 552 has a structure in which the electrode 552 is in contact with the side surface (or end portion) of each EL layer (103B, 103G, 103R) (note that the EL layers (103B, 103G, 103R) shown in FIG. 7B include hole injection / transport layers (104R, 104G, 104B), a light-emitting layer, a first electron transport layer (108B-1, 108G-1, 108R-1), and a second electron transport layer (108B-2, 108G-2, 108R-2)) via the electron injection layer 109 and the insulating layer 107. This makes it possible to prevent electrical short-circuiting between each EL layer (103B, 103G, 103R) and the electrode 552, more specifically, between the hole injection / transport layer (104B, 104G, 104R) of each EL layer (103B, 103G, 103R) and the electrode 552.

[0204] Through the above steps, the EL layers 103B, 103G, and 103R in the light-emitting devices 550B, 550G, and 550R can be separated and processed, respectively.

[0205] In addition, since pattern formation using photolithography is performed in the separation processing of these EL layers (EL layer 103B, EL layer 103G, and EL layer 103R), a high-definition light-emitting device (display panel) can be manufactured. Furthermore, the end portions (side surfaces) of the EL layers processed by pattern formation using photolithography have a shape that has approximately the same surface (or is located on approximately the same plane).

[0206] In the EL layer, the hole injection layer included in the hole transport region located between the anode and the light-emitting layer, in particular, often has high conductivity, and therefore, if it is formed as a layer common to adjacent light-emitting devices, it may cause crosstalk. Therefore, by separating the EL layer by pattern formation using photolithography as shown in this configuration example, it is possible to suppress the occurrence of crosstalk between adjacent light-emitting devices.

[0207] 8 includes a light-emitting device 550B, a light-emitting device 550G, a light-emitting device 550R, and a partition wall 528. The light-emitting device 700 includes the light-emitting device 550B, the light-emitting device 550G, the light-emitting device 550R, and the partition wall 528. The light-emitting device 550B, the light-emitting device 550G, the light-emitting device 550R, and the partition wall 528 are formed on a functional layer 520 provided on a first substrate 510. The functional layer 520 includes a driving circuit GD and a driving circuit SD each configured with a plurality of transistors, as well as wiring and the like that electrically connects these components. These driving circuits are, for example, electrically connected to the light-emitting device 550B, the light-emitting device 550G, and the light-emitting device 550R, respectively, and can drive these components.

[0208] The light-emitting device 550B, the light-emitting device 550G, and the light-emitting device 550R have the device structure shown in Embodiment 2. In particular, the EL layer 103 in the structure shown in FIG.

[0209] The specific configurations of the light-emitting devices shown in FIG. 8 are the same as those of the light-emitting device 550B, the light-emitting device 550G, and the light-emitting device 550R described with reference to FIG.

[0210] As shown in FIG. 8, the hole injection / transport layers (104B, 104G, 104R) of the EL layers (103B, 103G, 103R) of the light-emitting devices (550B, 550G, 550R) are smaller than the other functional layers constituting the EL layer, and are covered with the stacked functional layers.

[0211] In this configuration, the hole injection / transport layers (104B, 104G, 104R) in each EL layer are completely isolated by being covered with other functional layers, and therefore the insulating layer (107 in FIG. 1C) shown in Configuration Example 1 to prevent short-circuiting with the electrode 552 is not required.

[0212] Furthermore, since each EL layer (EL layer 103B, EL layer 103G, and EL layer 103R) in this configuration is patterned using photolithography during separation processing, the ends (side surfaces) of the processed EL layers have a shape that is approximately the same surface (or is located on approximately the same plane).

[0213] The EL layers (EL layer 103B, EL layer 103G, and EL layer 103R) of each light-emitting device have a gap 580 between adjacent light-emitting devices. Here, when the gap 580 is expressed as the distance SE between the EL layers of adjacent light-emitting devices (see FIG. 3A ), a smaller distance SE increases the aperture ratio and the resolution. On the other hand, a larger distance SE increases the tolerance for variations in the manufacturing process between adjacent light-emitting devices, thereby increasing the manufacturing yield. Because the light-emitting devices fabricated according to the present specification are suitable for miniaturization processes, the distance SE between the EL layers of adjacent light-emitting devices can be set to 0.5 μm or more and 5 μm or less, preferably 1 μm or more and 3 μm or less, more preferably 1 μm or more and 2.5 μm or less, and even more preferably 1 μm or more and 2 μm or less. Typically, the distance SE is preferably 1 μm or more and 2 μm or less (e.g., 1.5 μm or less).

[0214] In the EL layer, the hole injection layer included in the hole transport region located between the anode and the light-emitting layer, in particular, often has high conductivity, and therefore, if it is formed as a layer common to adjacent light-emitting devices, it may cause crosstalk. Therefore, by separating the EL layer by pattern formation using photolithography as shown in this configuration example, it is possible to suppress the occurrence of crosstalk between adjacent light-emitting devices.

[0215] In this specification and the like, 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 and the like, a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure. Because a light-emitting device with an MML structure is fabricated without using a metal mask, it has a higher degree of design freedom for pixel arrangement, pixel shape, and the like than a light-emitting device with an FMM structure or an MM structure.

[0216] The island-shaped EL layer in a light-emitting device with an MML structure is not formed by a metal mask pattern, but is formed by processing the EL layer after it has been formed. Therefore, it is possible to realize a light-emitting device with higher resolution or a higher aperture ratio than ever before. Furthermore, since the EL layer can be made separately for each color, it is possible to realize a light-emitting device with extremely vivid images, high contrast, and high display quality. Furthermore, by providing a sacrificial layer on the EL layer, damage to the EL layer during the manufacturing process can be reduced, thereby improving the reliability of the light-emitting device.

[0217] When the light-emitting layer is processed into an island shape, a structure in which the EL layer stacked up to the light-emitting layer is processed using photolithography is conceivable. In such a structure, the light-emitting layer may be damaged (e.g., damaged by processing), which may significantly impair reliability. Therefore, when manufacturing a display panel according to one embodiment of the present invention, it is preferable to use a method in which a sacrificial layer or the like is formed on a layer located above the light-emitting layer (e.g., a carrier transport layer or a carrier injection layer, more specifically, an electron transport layer or an electron injection layer) and the light-emitting layer is processed into an island shape. By applying this method, a highly reliable display panel can be provided.

[0218] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0219] 9A to 11B , a light-emitting device according to one embodiment of the present invention will be described. Note that a light-emitting device 700 shown in FIGS. 9A to 11B includes the light-emitting device described in Embodiment 2. The light-emitting device 700 described in this embodiment can be applied to a display portion of an electronic device or the like, and therefore can also be called a display panel.

[0220] 9A, the light-emitting device 700 described in this embodiment includes a display region 231, which includes a set of pixels 703(i, j). Also, as shown in FIG. 9B, the light-emitting device 700 includes a set of pixels 703(i+1, j) adjacent to the set of pixels 703(i, j).

[0221] It should be noted that multiple pixels can be used for pixel 703(i,j). For example, multiple pixels that display colors with different hues can be used. Each of the multiple pixels can be referred to as a sub-pixel. Alternatively, a set of multiple sub-pixels can be referred to as a pixel.

[0222] This allows the colors displayed by the plurality of pixels to be mixed by additive or subtractive color mixing, or allows colors of hues that cannot be displayed by individual pixels to be displayed.

[0223] Specifically, pixel 702B(i,j) displaying blue, pixel 702G(i,j) displaying green, and pixel 702R(i,j) displaying red can be used as pixel 703(i,j). Furthermore, pixel 702B(i,j), pixel 702G(i,j), and pixel 702R(i,j) can each be referred to as a sub-pixel.

[0224] Furthermore, a pixel that displays white or the like may be added to the above set and used as pixel 703(i,j).Furthermore, a pixel that displays cyan, a pixel that displays magenta, and a pixel that displays yellow may each be used as a subpixel for pixel 703(i,j).

[0225] In addition to the above pair, a pixel that emits infrared light may be used as pixel 703(i,j). Specifically, a pixel that emits light including light having a wavelength of 650 nm or more and 1000 nm or less may be used as pixel 703(i,j).

[0226] 9A, the display region 231 has a driver circuit GD and a driver circuit SD in its periphery. The display region 231 also has terminals 519 electrically connected to the driver circuits GD and SD. The terminals 519 can be electrically connected to a flexible printed circuit FPC1, for example, as shown in FIG. 11A.

[0227] The driver circuit GD has a function of supplying a first selection signal and a second selection signal. For example, the driver circuit GD is electrically connected to a conductive film G1(i) described later to supply a first selection signal, and is electrically connected to a conductive film G2(i) described later to supply a second selection signal. The driver circuit SD has a function of supplying an image signal and a control signal, and the control signal includes a first level and a second level. For example, the driver circuit SD is electrically connected to a conductive film S1g(j) described later to supply an image signal, and is electrically connected to a conductive film S2g(j) described later to supply a control signal.

[0228] 11A shows cross-sectional views of the light-emitting device taken along dashed dotted lines X1-X2 and X3-X4 in FIG. 9A. As shown in FIG. 11A, the light-emitting device 700 has a functional layer 520 between a first substrate 510 and a second substrate 770. The functional layer 520 includes the above-described drive circuit GD, drive circuit SD, and the like, as well as wiring and the like that electrically connects these. In FIG. 11A, the functional layer 520 includes a pixel circuit 530B(i,j), a pixel circuit 530G(i,j), and a drive circuit GD, but is not limited to this.

[0229] Furthermore, each pixel circuit (e.g., pixel circuit 530B(i,j) and pixel circuit 530G(i,j) shown in FIG. 11A ) included in the functional layer 520 is electrically connected to each light-emitting device (e.g., light-emitting device 550B(i,j) and light-emitting device 550G(i,j) shown in FIG. 11A ) formed on the functional layer 520. Specifically, the light-emitting device 550B(i,j) is electrically connected to the pixel circuit 530B(i,j) through the opening 591B, and the light-emitting device 550G(i,j) is electrically connected to the pixel circuit 530G(i,j) through the opening 591G. Furthermore, an insulating layer 705 is provided on the functional layer 520 and each light-emitting device, and the insulating layer 705 has the function of bonding the second substrate 770 and the functional layer 520 together.

[0230] Note that a substrate provided with touch sensors arranged in a matrix can be used as the second substrate 770. For example, a substrate provided with a capacitive touch sensor or an optical touch sensor can be used as the second substrate 770. In this way, the light-emitting device of one embodiment of the present invention can be used as a touch panel.

[0231] FIG. 10A shows a specific configuration of the pixel circuit 530G(i, j).

[0232] 10A, the pixel circuit 530G(i,j) includes a switch SW21, a switch SW22, a transistor M21, a capacitor C21, and a node N21. The pixel circuit 530G(i,j) also includes a node N22, a capacitor C22, and a switch SW23.

[0233] The transistor M21 has a gate electrode electrically connected to the node N21, a first electrode electrically connected to the light-emitting device 550G(i, j), and a second electrode electrically connected to the conductive film ANO.

[0234] The switch SW21 has a first terminal electrically connected to the node N21 and a second terminal electrically connected to the conductive film S1g(j), and has a function of controlling the conductive state or non-conductive state based on the potential of the conductive film G1(i).

[0235] The switch SW22 has a first terminal electrically connected to the conductive film S2g(j) and has a function of controlling the conductive state or non-conductive state based on the potential of the conductive film G2(i).

[0236] The capacitor C21 has a conductive film electrically connected to the node N21 and a conductive film electrically connected to the second electrode of the switch SW22.

[0237] This allows an image signal to be stored in node N21. Alternatively, the potential of node N21 can be changed using switch SW22. Alternatively, the intensity of light emitted by light-emitting device 550G(i, j) can be controlled using the potential of node N21.

[0238] 10B shows an example of a specific structure of the transistor M21 described with reference to FIG 10A. Note that the transistor M21 can be a bottom-gate transistor, a top-gate transistor, or the like, as appropriate.

[0239] 10B includes a semiconductor film 508, a conductive film 504, an insulating film 506, a conductive film 512A, and a conductive film 512B. The transistor is formed over, for example, an insulating film 501C. The transistor also includes an insulating film 516 (insulating films 516A and 516B) and an insulating film 518.

[0240] The semiconductor film 508 has a region 508A electrically connected to the conductive film 512A and a region 508B electrically connected to the conductive film 512B. The semiconductor film 508 has a region 508C between the region 508A and the region 508B.

[0241] The conductive film 504 has a region overlapping with the region 508C, and functions as a gate electrode.

[0242] The insulating film 506 has a region sandwiched between the semiconductor film 508 and the conductive film 504. The insulating film 506 functions as a first gate insulating film.

[0243] The conductive film 512A has a function as either a source electrode or a drain electrode, and the conductive film 512B has the other function as either a source electrode or a drain electrode.

[0244] The conductive film 524 can also be used for a transistor. The conductive film 524 has a region where the semiconductor film 508 is sandwiched between the conductive film 524 and the conductive film 504. The conductive film 524 functions as a second gate electrode. The insulating film 501D is sandwiched between the semiconductor film 508 and the conductive film 524 and functions as a second gate insulating film.

[0245] The insulating film 516 functions as, for example, a protective film that covers the semiconductor film 508. Specific examples of the insulating film 516 that can be used include a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, 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.

[0246] The insulating film 518 is preferably formed using a material that has a function of suppressing diffusion of, for example, oxygen, hydrogen, water, an alkali metal, an alkaline earth metal, or the like. Specifically, for example, silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, or the like can be used for the insulating film 518. Furthermore, the number of nitrogen atoms contained in silicon oxynitride and aluminum oxynitride is preferably larger than the number of oxygen atoms contained therein.

[0247] Note that a semiconductor film to be used for a transistor in a pixel circuit can be formed in the same process as a semiconductor film to be used for a transistor in a driver circuit. For example, a semiconductor film having the same composition as that of a semiconductor film to be used for a transistor in a pixel circuit can be used for the driver circuit.

[0248] Furthermore, a semiconductor containing an element of Group 14 can be used for the semiconductor film 508. Specifically, a semiconductor containing silicon can be used for the semiconductor film 508.

[0249] Furthermore, hydrogenated amorphous silicon can be used for the semiconductor film 508. Alternatively, microcrystalline silicon or the like can be used for the semiconductor film 508. This makes it possible to provide a light-emitting device with less display unevenness than, for example, a light-emitting device (or display panel) using polysilicon for the semiconductor film 508. Alternatively, it is easy to increase the size of the light-emitting device.

[0250] Furthermore, polysilicon can be used for the semiconductor film 508. This allows the field-effect mobility of the transistor to be higher than that of a transistor using hydrogenated amorphous silicon for the semiconductor film 508, for example. Alternatively, the driving capability can be improved compared to that of a transistor using hydrogenated amorphous silicon for the semiconductor film 508, for example. Alternatively, the aperture ratio of a pixel can be improved compared to that of a transistor using hydrogenated amorphous silicon for the semiconductor film 508, for example.

[0251] Alternatively, the reliability of the transistor can be improved compared to a transistor using hydrogenated amorphous silicon for the semiconductor film 508, for example.

[0252] Alternatively, the temperature required to manufacture the transistor can be lower than that of a transistor using single crystal silicon, for example.

[0253] Alternatively, a semiconductor film used for a transistor in a driver circuit can be formed in the same process as a semiconductor film used for a transistor in a pixel circuit. Alternatively, the driver circuit can be formed over the same substrate as the substrate on which the pixel circuit is formed. Alternatively, the number of components constituting an electronic device can be reduced.

[0254] Furthermore, single crystal silicon can be used for the semiconductor film 508. This allows for higher definition than, for example, a light-emitting device (or a display panel) using hydrogenated amorphous silicon for the semiconductor film 508. Alternatively, for example, a light-emitting device with less display unevenness than, for example, a light-emitting device using polysilicon for the semiconductor film 508 can be provided. Alternatively, for example, smart glasses or a head-mounted display can be provided.

[0255] Furthermore, metal oxide can be used for the semiconductor film 508. This allows the pixel circuit to retain an image signal for a longer period of time compared to a pixel circuit that uses a transistor with hydrogenated amorphous silicon as the semiconductor film. Specifically, the selection signal can be supplied at a frequency of less than 30 Hz, preferably less than 1 Hz, and more preferably less than once per minute, while suppressing the occurrence of flicker. As a result, fatigue accumulated in the user of the electronic device can be reduced. Furthermore, power consumption associated with driving can be reduced.

[0256] An oxide semiconductor can be used for the semiconductor film 508. Specifically, an oxide semiconductor containing indium, an oxide semiconductor containing indium, gallium, and zinc, or an oxide semiconductor containing indium, gallium, zinc, and tin can be used for the semiconductor film 508.

[0257] Note that by using an oxide semiconductor for the semiconductor film, a transistor having a smaller leakage current in an off state than a transistor using hydrogenated amorphous silicon for the semiconductor film can be obtained. Therefore, it is preferable to use a transistor using an oxide semiconductor for the semiconductor film as a switch or the like. Note that a circuit using a transistor using an oxide semiconductor for the semiconductor film as a switch can hold the potential of a floating node for a longer time than a circuit using a transistor using hydrogenated amorphous silicon for the semiconductor film as a switch.

[0258] 11A shows a light-emitting device having a structure (top emission type) in which light is extracted on the second substrate 770 side, but as shown in Fig. 11B, a light-emitting device having a structure (bottom emission type) in which light is extracted on the first substrate 510 side may also be used. In the case of a bottom emission type light-emitting device, the first electrode 101 is formed to function as a semi-transmissive and semi-reflective electrode, and the second electrode 102 is formed to function as a reflective electrode.

[0259] Although an active matrix light-emitting device has been described in FIGS. 11A and 11B, the structure of the light-emitting device described in Embodiment 2 may be applied to a passive matrix light-emitting device shown in FIGS. 12A and 12B.

[0260] 12A is a perspective view showing a passive matrix light-emitting device, and FIG. 12B is a cross-sectional view taken along dashed line X-Y in FIG. 12A. In FIGS. 12A and 12B, an electrode 952 and an electrode 956 are provided on a substrate 951, and an EL layer 955 is provided between the electrode 952 and the electrode 956. An end of the electrode 952 is covered with an insulating layer 953. A partition layer 954 is provided on the insulating layer 953. The sidewalls of the partition layer 954 are inclined such that the distance between one sidewall and the other sidewall decreases with increasing distance from the substrate surface. That is, the cross section of the partition layer 954 in the minor axis direction is trapezoidal, with the lower side (the side facing the same direction as the surface of the insulating layer 953 and in contact with the insulating layer 953) being shorter than the upper side (the side facing the same direction as the surface of the insulating layer 953 and not in contact with the insulating layer 953). In this manner, by providing the partition layer 954, defects in the light-emitting device due to static electricity or the like can be prevented.

[0261] Note that the structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0262] Embodiment 5 In this embodiment, structures of electronic devices of one embodiment of the present invention will be described with reference to FIGS. 13A to 15B. FIG.

[0263] 13A to 15B are diagrams illustrating the structure of an electronic device of one embodiment of the present invention. FIG. 13A is a block diagram of the electronic device, and FIGS. 13B to 13E are perspective views illustrating the structure of the electronic device. FIGS. 14A to 14E are perspective views illustrating the structure of the electronic device. FIGS. 15A and 15B are perspective views illustrating the structure of the electronic device.

[0264] An electronic device 5200B described in this embodiment includes an arithmetic device 5210 and an input / output device 5220 (see FIG. 13A).

[0265] The arithmetic unit 5210 has a function of receiving operation information and a function of supplying image information based on the operation information.

[0266] The input / output device 5220 has a display unit 5230, an input unit 5240, a detection unit 5250, a communication unit 5290, a function to supply operation information, and a function to be supplied with image information. The input / output device 5220 also has a function to supply detection information, a function to supply communication information, and a function to be supplied with communication information.

[0267] The input unit 5240 has a function of supplying operation information. For example, the input unit 5240 supplies operation information based on an operation by the user of the electronic device 5200B.

[0268] Specifically, the input unit 5240 can use a keyboard, hardware buttons, a pointing device, a touch sensor, an illuminance sensor, an imaging device, a voice input device, an eye-gaze input device, an attitude detection device, or the like.

[0269] The display portion 5230 has a function of displaying a display panel and displaying image information. For example, the display panel described in Embodiment 2 can be used as the display portion 5230.

[0270] The detection unit 5250 has a function of supplying detection information, for example, a function of detecting the surrounding environment in which the electronic device is used and supplying the detected information.

[0271] Specifically, an illuminance sensor, an imaging device, a posture detection device, a pressure sensor, a human sensor, or the like can be used for the detection unit 5250 .

[0272] The communication unit 5290 has a function of receiving and supplying communication information. For example, it has a function of connecting to other electronic devices or communication networks by wireless communication or wired communication. Specifically, it has functions such as wireless local area communication, telephone communication, and short-range wireless communication.

[0273] FIG. 13B shows an electronic device having an outer shape that conforms to a cylindrical pillar or the like. An example of such an electronic device is a digital signage device. The display panel according to one embodiment of the present invention can be applied to the display portion 5230. The display panel may have a function of changing the display method depending on the illuminance of the usage environment. The display panel may also have a function of detecting the presence of a person and changing the display content. This allows the display panel to be installed on a pillar of a building, for example. Alternatively, advertisements, guides, or the like can be displayed.

[0274] 13C shows an electronic device that has the function of generating image information based on the trajectory of a pointer used by a user. Examples include an electronic whiteboard, an electronic bulletin board, and an electronic signboard. Specifically, a display panel with a diagonal length of 20 inches or more, preferably 40 inches or more, and more preferably 55 inches or more can be used. Alternatively, multiple display panels can be arranged to form a single display area. Alternatively, multiple display panels can be arranged to form a multi-screen.

[0275] 13D shows an electronic device that can receive information from another device and display it on the display unit 5230. An example of such an electronic device is a wearable electronic device. Specifically, it can display several options, or the user can select some options and send a reply to the sender of the information. Alternatively, it can have a function to change the display method depending on the illuminance of the usage environment. This can reduce the power consumption of the wearable electronic device, for example. Alternatively, it can display an image on the display unit 5230 so that the electronic device can be used effectively even in an environment with strong external light, such as outdoors on a sunny day.

[0276] 13E shows an electronic device having a display unit 5230 with a curved surface that gently curves along the side of the housing. An example is a mobile phone. The display unit 5230 includes a display panel that has a function of displaying information on, for example, the front, side, top, and back of the mobile phone. This allows information to be displayed not only on the front, but also on the side, top, and back of the mobile phone.

[0277] 14A shows an electronic device that can receive information from the Internet and display it on the display unit 5230. An example of such an electronic device is a smartphone. For example, a created message can be checked on the display unit 5230. Alternatively, the created message can be transmitted to another device. Alternatively, the smartphone has a function of changing the display method depending on the illuminance of the usage environment. This can reduce the power consumption of the smartphone. Alternatively, for example, an image can be displayed on the display unit 5230 so that the smartphone can be used suitably even in an environment with strong external light, such as outdoors on a sunny day.

[0278] FIG. 14B shows an electronic device that can use a remote controller as the input unit 5240. An example is a television system. For example, information can be received from a broadcasting station or the Internet and displayed on the display unit 5230. Alternatively, a user can be photographed using the detection unit 5250. An image of the user can be transmitted. The user's viewing history can be acquired and provided to a cloud service. Recommended information can be acquired from a cloud service and displayed on the display unit 5230. Programs or videos can be displayed based on the recommended information. Alternatively, the electronic device can have a function to change the display method depending on the illuminance of the usage environment. This allows images to be displayed on the display unit 5230 so that the device can be used effectively even when strong external light shines indoors on a sunny day.

[0279] 14C shows an electronic device that can receive learning materials from the Internet and display them on the display unit 5230. An example is a tablet computer. A report can be input using the input unit 5240 and sent to the Internet. Alternatively, corrections or evaluations of the report can be obtained from a cloud service and displayed on the display unit 5230. Alternatively, suitable learning materials can be selected and displayed based on the evaluation.

[0280] For example, an image signal can be received from another electronic device and displayed on the display unit 5230. Alternatively, the display unit 5230 can be used as a sub-display by being placed on a stand or the like. This allows images to be displayed on the tablet computer so that the tablet computer can be used suitably even in an environment with strong external light, such as outdoors on a sunny day.

[0281] FIG. 14D shows an electronic device having multiple display units 5230. An example is a digital camera. For example, an image can be captured by the detection unit 5250 and displayed on the display unit 5230. Alternatively, the captured image can be displayed on the display unit 5230. Alternatively, the captured image can be decorated using the input unit 5240. Alternatively, a message can be attached to the captured image. Alternatively, the captured image can be transmitted to the Internet. Alternatively, the electronic device has a function to change the capture conditions depending on the illuminance of the usage environment. This allows the subject to be displayed on the display unit 5230 so that it can be viewed appropriately even in an environment with strong external light, such as outdoors on a sunny day.

[0282] 14E shows an electronic device that can control another electronic device using the electronic device of this embodiment as a master, with the other electronic device used as a slave. One example is a portable personal computer. For example, part of the image information can be displayed on the display unit 5230, and another part of the image information can be displayed on the display unit of the other electronic device. Alternatively, an image signal can be supplied. Alternatively, information to be written can be obtained from the input unit of the other electronic device using the communication unit 5290. This allows, for example, a portable personal computer to utilize a large display area.

[0283] FIG. 15A shows an electronic device having a detector 5250 that detects acceleration or orientation. An example is a goggle-type electronic device. The detector 5250 can provide information related to the user's position or the direction the user is facing. Alternatively, the electronic device can generate image information for the right eye and image information for the left eye based on the user's position or the direction the user is facing. Alternatively, the display unit 5230 has a display area for the right eye and a display area for the left eye. This allows, for example, an image of a virtual reality space that provides an immersive experience to be displayed on the display unit 5230.

[0284] 15B shows an electronic device having a detection unit 5250 that detects an imaging device, acceleration, or orientation. An example is a glasses-type electronic device. The detection unit 5250 can provide information related to the user's position or the direction the user is facing. Alternatively, the electronic device can generate image information based on the user's position or the direction the user is facing. This allows, for example, information to be attached to a real-world scene and displayed. Alternatively, an image of an augmented reality space can be displayed on the glasses-type electronic device.

[0285] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0286] In this embodiment, a structure in which the light-emitting device described in Embodiment 2 is used as a lighting device will be described with reference to Fig. 16. Fig. 16A is a cross-sectional view taken along line e-f in the top view of the lighting device shown in Fig. 16B.

[0287] In the lighting device of this embodiment, a first electrode 401 is formed over a light-transmitting substrate 400 which serves as a support. The first electrode 401 corresponds to the first electrode 101 in Embodiment 2. When light is extracted from the first electrode 401 side, the first electrode 401 is formed using a light-transmitting material.

[0288] A pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400 .

[0289] An EL layer 403 is formed over the first electrode 401. The EL layer 403 has a structure corresponding to the EL layer 103 in Embodiment Mode 2. For the structure thereof, refer to the description therein.

[0290] A second electrode 404 is formed to cover the EL layer 403. The second electrode 404 corresponds to the second electrode 102 in Embodiment Mode 2. When light is extracted from the first electrode 401 side, the second electrode 404 is formed using a material with high reflectivity. The second electrode 404 is connected to a pad 412 to supply a voltage.

[0291] As described above, the lighting device described in this embodiment has a light-emitting device including the first electrode 401, the EL layer 403, and the second electrode 404. Since the light-emitting device has high emission efficiency, the lighting device in this embodiment can have low power consumption.

[0292] The lighting device is completed by bonding and sealing the substrate 400 on which the light-emitting device having the above structure is formed and the sealing substrate 407 using sealants 405 and 406. Either the sealant 405 or 406 can be used. Also, a desiccant can be mixed into the inner sealant 406 (not shown in FIG. 16B ), which can absorb moisture and improve reliability.

[0293] Furthermore, the pad 412 and a part of the first electrode 401 can be provided as an external input terminal by extending them outside the sealing materials 405 and 406. Furthermore, an IC chip 420 or the like on which a converter or the like is mounted may be provided thereon.

[0294] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0295] Embodiment 7 In this embodiment, an application example of a lighting device manufactured using a light-emitting device which is one embodiment of the present invention or a light-emitting device which is a part of the light-emitting device will be described with reference to FIGS.

[0296] The indoor lighting device can be applied as a ceiling light 8001. The ceiling light 8001 can be either a direct ceiling mounted type or a ceiling recessed type. Such lighting devices are constructed by combining a light emitting device with a housing or a cover. In addition, it can also be applied to a cord pendant type (a type suspended from the ceiling by a cord).

[0297] The foot lamp 8002 can also project light onto the floor, improving safety around the feet. For example, it is effective for use in bedrooms, stairs, or corridors. In this case, the size and shape can be changed appropriately depending on the size and structure of the room. It can also be used as a stationary lighting device configured by combining a light-emitting device with a support base.

[0298] The sheet lighting 8003 is a thin sheet-like lighting device. Since it is attached to a wall surface, it does not take up much space and can be used for a wide range of purposes. It can also be easily made larger. It can also be used on a curved wall surface or housing.

[0299] It is also possible to use a lighting device 8004 in which light from a light source is controlled to only a desired direction.

[0300] The desk lamp 8005 includes a light source 8006 , and the light-emitting device according to one embodiment of the present invention or a light-emitting device that is a part of the light-emitting device can be used as the light source 8006 .

[0301] In addition to the above, by applying the light-emitting device of one embodiment of the present invention or a light-emitting device that is a part of the light-emitting device to a part of furniture installed in a room, the lighting device can have the function of the furniture.

[0302] As described above, various lighting devices using the light-emitting device can be obtained. Note that these lighting devices are included in one embodiment of the present invention.

[0303] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0304] In this example, films (laminated films, mixed films, etc.) made of different materials or structures were prepared on glass substrates, and the results of heat resistance tests performed on the obtained samples (films) are shown. Six types of samples were prepared by varying the combination of multiple heteroaromatic compounds or film structures. The structure of each sample is shown in Table 1 below, along with the observation results. The chemical formulas of the materials used in this example are shown below.

[0305]

[0306] The manufacturing method of each sample (Sample 1 to Sample 9) will be described below.

[0307] 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.

[0308] 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.

[0309] 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.

[0310] 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.

[0311] 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.

[0312] Sample 5 is a laminated film including 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.

[0313] 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.

[0314] 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).

[0315] Sample 8 is a laminated film including 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 40 nm layer of NBPhen, a 20 nm layer of NBPhen was evaporated.

[0316] Sample 9 is a laminated film including 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 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).

[0317] Each sample prepared in this manner was observed visually and under an optical microscope (Olympus Corporation, Semiconductor / FPD Inspection Microscope MX61L).

[0318] Photographs of the samples produced in this example (observed in a dark field at 100x magnification) are shown in Figures 18A to 18E and 19A to 19D. As comparative examples, unbaked samples (ref) of each sample are also shown.

[0319] 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, a triangle indicates that a change occurred in the appearance of the sample, although the formation of crystals was unclear, and a cross indicates that crystals were formed. Triangles indicate that a clear determination could not be made.

[0320]

[0321] 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.

[0322] 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.

[0323] The results of Example 1 revealed 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 2. The chemical formulas of the materials used in this example are shown below.

[0324]

[0325]

[0326] <<Fabrication of Light-Emitting Device 1>> The light-emitting device 1 shown in this example has a structure in which, as shown in FIG. 20 , 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, and a second electrode 903 is stacked on the electron injection layer 915.

[0327] First, a first electrode 901 was formed on a substrate 900. The electrode area was 4 mm ２The 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.

[0328] 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.

[0329] 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).

[0330] 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.

[0331] Next, a light-emitting layer 913 was formed on the hole-transporting layer 912 .

[0332] 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.

[0333] 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.

[0334] 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.

[0335] 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.

[0336] 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.

[0337] 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).

[0338] <<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.

[0339] <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. 21, the current efficiency-luminance characteristics in Fig. 22, the luminance-voltage characteristics in Fig. 23, the current-voltage characteristics in Fig. 24, the external quantum efficiency-luminance characteristics in Fig. 25, and the emission spectrum in Fig. 26. 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.

[0340]

[0341] 21 to 26 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.

[0342] 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 27. In Figure 27, 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.

[0343] The results shown in FIG. 27 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.

[0344] 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.

[0345]

[0346] 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) was added thereto, and the mixture was stirred at 120°C for 10 hours.

[0347] 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.

[0348]

[0349] 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%.

[0350] Nuclear magnetic resonance spectroscopy of the solid obtained above ( １The results of the analysis by H-NMR are shown below. From these results, it was found that 2mpPCBPDBq was obtained in this example.

[0351] 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).

[0352] 100: light-emitting device, 101: first electrode, 102: second electrode, 103: EL layer, 103B: EL layer, 103G: EL layer, 103R: EL layer, 104B: hole injection / transport layer, 104G: hole injection / transport layer, 104R: hole injection / transport layer, 107: insulating layer, 107B: insulating layer, 107G: insulating layer, 107R: insulating layer, 108: electron transport layer, 108-1: first electron transport layer, 108-2: second electron transport layer, 108B: electron transport layer, 108G: electron transport layer, 108R: electron transport layer, 109: electron injection layer, 111: hole injection layer, 112 : hole transport layer, 113: light emitting layer, 114: electron transport layer, 115: electron injection layer, 231: display region, 400: substrate, 401: first electrode, 403: EL layer, 404: second electrode, 405: sealing material, 406: sealing material, 407: sealing substrate, 412: pad, 420: IC chip, 501C: insulating film, 501D: insulating film, 504: conductive film, 506: insulating film, 508: semiconductor film, 508A: region, 508B: region, 508C: region, 510: first substrate, 512A: conductive film, 512B: conductive film, 519: terminal, 516: insulating film, 516A: insulating film, 516B: insulating film, 518: insulating film, 520: functional layer, 524: conductive film, 528: partition wall, 528B: opening, 528G: opening, 528R: opening, 530B: pixel circuit, 530G: pixel circuit, 550B: light-emitting device, 550G: light-emitting device, 550R: light-emitting device, 551B: electrode, 551G: electrode, 551R: electrode, 552: electrode, 580: gap, 591G: opening, 591B: opening, 700: light-emitting device, 702B: pixel, 702G: pixel, 702R: pixel, 703: pixel, 705: insulating layer, 770: substrate, 900: substrate, 90 1: first electrode, 903: second electrode, 911: hole injection layer, 912: hole transport layer, 913: light-emitting layer, 914: electron transport layer, 915: electron injection layer, 951: substrate, 952: electrode, 953: insulating layer, 954: partition layer, 955: EL layer, 956: electrode, 5200B: electronic device, 5210: arithmetic unit, 5220: input / output device, 5230: display unit, 5240: input unit, 5250: detection unit, 5290: communication unit, 8001: ceiling light, 8002: foot lamp, 8003: sheet-like lighting, 8004: lighting device, 8005: desk lamp, 8006: light source

Claims

1. A second electrode is provided over a first electrode with an EL layer sandwiched therebetween; the EL layer includes at least a light-emitting layer, a first electron transport layer, a second electron transport layer, and an electron injection layer; the first electron transport layer on the light emitting layer; the second electron transport layer on the first electron transport layer; an insulating layer in contact with a side surface of the light-emitting layer, a side surface of the first electron transport layer, and a side surface of the second electron transport layer; the electron injection layer on the second electron transport layer; the insulating layer is located between a side surface of the light emitting layer, a side surface of the first electron transport layer, and a side surface of the second electron transport layer and the electron injection layer; The second electron transport layer comprises a heteroaromatic compound having at least one heteroaromatic ring and an organic compound different from the heteroaromatic compound.

2. A second electrode is provided over a first electrode with an EL layer sandwiched therebetween; the EL layer includes at least a light-emitting layer, a first electron transport layer, a second electron transport layer, and an electron injection layer; the first electron transport layer on the light emitting layer; the second electron transport layer on the first electron transport layer; an insulating layer in contact with a side surface of the light-emitting layer, a side surface of the first electron transport layer, and a side surface of the second electron transport layer; the electron injection layer on the second electron transport layer; the insulating layer is located between a side surface of the light emitting layer, a side surface of the first electron transport layer, and a side surface of the second electron transport layer and the electron injection layer; the second electron transport layer comprises a first heteroaromatic compound having at least one heteroaromatic ring and an organic compound different from the first heteroaromatic compound; the first electron transport layer comprising a second heteroaromatic compound having at least one heteroaromatic ring.

3. A light emitting apparatus comprising the light emitting device according to claim 1 or 2, and a transistor or a substrate.

4. a first light emitting device and a second light emitting device adjacent to each other; The first light emitting device has a second electrode on a first electrode with a first EL layer sandwiched therebetween; the first EL layer includes at least a first light-emitting layer, a first electron transport layer, a second electron transport layer, and an electron injection layer; the first electron transport layer is disposed on the first light emitting layer; the second electron transport layer on the first electron transport layer; a first insulating layer in contact with a side surface of the first light-emitting layer, a side surface of the first electron transport layer, and a side surface of the second electron transport layer; the electron injection layer on the second electron transport layer; the first insulating layer is located between a side surface of the first light emitting layer, a side surface of the first electron transport layer, and a side surface of the second electron transport layer and the electron injection layer; the second light emitting device has a second electrode on a third electrode with a second EL layer sandwiched therebetween; the second EL layer includes at least a second light-emitting layer, a third electron transport layer, a fourth electron transport layer, and the electron injection layer; the third electron transport layer is disposed on the second light-emitting layer; the fourth electron transport layer being disposed on the third electron transport layer; a second insulating layer in contact with a side surface of the second light-emitting layer and a side surface of the third electron transport layer; the electron injection layer is disposed on the fourth electron transport layer; the second insulating layer is located between a side surface of the second light emitting layer and a side surface of the third electron transport layer and between the electron injection layer and the side surface of the second light emitting layer and the third electron transport layer; the second electron transport layer and the fourth electron transport layer each include a heteroaromatic compound having at least one heteroaromatic ring and an organic compound different from the heteroaromatic compound.

5. a first light emitting device and a second light emitting device adjacent to each other; The first light emitting device has a second electrode on a first electrode with a first EL layer sandwiched therebetween; the first EL layer includes at least a first light-emitting layer, a first electron transport layer, a second electron transport layer, and an electron injection layer; the first electron transport layer is disposed on the first light emitting layer; the second electron transport layer on the first electron transport layer; a side surface of the first light-emitting layer, a side surface of the first electron transport layer, and a side surface of the second electron transport layer; a first insulating layer in contact with the the electron injection layer on the second electron transport layer; the first insulating layer is located between a side surface of the first light emitting layer, a side surface of the first electron transport layer, and a side surface of the second electron transport layer and the electron injection layer; the second light emitting device has a second electrode on a third electrode with a second EL layer sandwiched therebetween; the second EL layer includes at least a second light-emitting layer, a third electron transport layer, a fourth electron transport layer, and the electron injection layer; the third electron transport layer is disposed on the second light-emitting layer; the fourth electron transport layer being disposed on the third electron transport layer; a second insulating layer in contact with a side surface of the second light-emitting layer and a side surface of the third electron transport layer; the electron injection layer is disposed on the fourth electron transport layer; the second insulating layer is located between a side surface of the second light emitting layer and a side surface of the third electron transport layer and between the electron injection layer and the side surface of the second light emitting layer and the third electron transport layer; the second electron transport layer and the fourth electron transport layer each have a first heteroaromatic compound having at least one heteroaromatic ring and an organic compound different from the first heteroaromatic compound; the first electron transport layer and the third electron transport layer comprise a second heteroaromatic compound having at least one heteroaromatic ring.

6. In claim 4 or claim 5, the second electron transport layer is located between a side surface of the first electron transport layer, a side surface of the third electron transport layer, a side surface of the first light-emitting layer, and a side surface of the second light-emitting layer and the second electrode.

7. A light emitting device according to any one of claims 3 to 6, An electronic device having at least one of a detection unit, an input unit, and a communication unit.

8. A lighting device comprising: the light-emitting device according to claim 3; and a housing.