light-emitting device

Abstract

A low-voltage, high-current light-emitting device suitable for high-resolution display is provided. A tandem light-emitting device, fabricated by a photolithographic process, is provided, comprising multiple light-emitting units and an interlayer between them. The interlayer includes a first region containing a metal or metal oxide, a first organic compound having a first π-electron-deficient heteroaromatic ring with an electron-donating group, and a second organic compound having a second π-electron-deficient heteroaromatic ring. The LUMO level of the second organic compound is more than or equal to 0.30 eV lower than that of the first organic compound.

Description

Background of the invention 1. Field of the invention

[0001] One embodiment of the present invention relates to a light-emitting device.

[0002] Note that an embodiment of the present invention is not limited to the above technical field. Examples of the technical field of an embodiment of the present invention include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device (e.g., a touch sensor), an input / output device (e.g., a touch screen), operating methods thereof, and manufacturing methods thereof. 2. Description of the state of the art

[0003] In recent years, display devices have been developed for a variety of applications. For example, a home television (also referred to as a TV or television receiver), a digital signage device, and a public information display (PID) are being developed as large-scale display devices, and a smartphone and a tablet device, each equipped with a touchscreen, are being developed as small-scale display devices.

[0004] At the same time, there is also a demand for increased display resolution. For example, devices for virtual reality (VR), augmented reality (AR), substitutional reality (SR), or mixed reality (MR) are listed and actively developed as devices requiring high-resolution displays.

[0005] Light-emitting devices (also referred to as light-emitting elements) are actively developed as display elements used in display devices. Light-emitting devices utilizing electroluminescence (electroluminescence is referred to as EL hereinafter, and such devices are also referred to as EL devices or EL elements), especially light-emitting devices primarily using organic compounds, are suitable for display devices because of their features such as ease of reducing thickness and weight, high response speed to input signals, and operation with a constant DC power source.

[0006] To achieve a higher-resolution light-emitting device using a light-emitting device, instead of an evaporation method using a metal mask, patterning an organic layer by a photolithography technique using a photoresist or the like is being explored. By using the photolithography technique, a high-resolution display device with a pitch of several micrometers can be obtained (see, for example, Patent Document 1). [Reference][Patent document] [Patent Document 1] Japanese translation of PCT International Application No. 2018-521459 [Patent Document 2] PCT International Publication No. 2021 / 045178 Summary of the invention

[0007] It is known that exposure of EL layers in a light-emitting device to atmospheric components such as water and oxygen affects initial properties or reliability, and it is therefore common knowledge that EL layers are treated in a near-vacuum atmosphere. In particular, an electron injection layer or an interlayer of a tandem light-emitting device containing a material with a donor property, typically an alkali metal, an alkaline earth metal, or a compound thereof, that is highly reactive with water or oxygen, rapidly deteriorates and loses its function as an interlayer when the surface of the EL layer is exposed to air.

[0008] However, processing steps using the aforementioned photolithography technique inevitably expose the surface of the EL layer to air. Favorable properties are difficult to obtain in light-emitting devices fabricated using photolithography.

[0009] In particular, processing with a photolithography technique often leads to a problem of increased operating voltage.

[0010] In view of the foregoing, an object of one embodiment of the present invention is to provide a novel light-emitting device having a tandem structure. An object of another embodiment of the present invention is to provide a highly efficient light-emitting device having a tandem structure. Another object of one embodiment of the present invention is to provide a light-emitting device having a tandem structure and a low operating voltage. Another object of another embodiment of the present invention is to provide a highly reliable light-emitting device having a tandem structure. An object of another embodiment of the present invention is to provide a highly efficient and highly reliable light-emitting device having a tandem structure.An object of another embodiment of the present invention is to provide a highly reliable light-emitting device with a tandem structure and a low operating voltage. An object of another embodiment of the present invention is to provide a highly efficient and highly reliable light-emitting device with a tandem structure and a low operating voltage.

[0011] Another object of an embodiment of the present invention is to provide a novel light-emitting device having a tandem structure and manufactured by a photolithography process. Another object of another embodiment of the present invention is to provide a highly efficient light-emitting device having a tandem structure and manufactured by a photolithography process. Another object of an embodiment of the present invention is to provide a novel light-emitting device having a tandem structure and a low operating voltage and manufactured by a photolithography process. Another object of an embodiment of the present invention is to provide a highly reliable light-emitting device having a tandem structure and manufactured by a photolithography process.An object of another embodiment of the present invention is to provide a highly reliable light-emitting device with high emission efficiency, which has a tandem structure and is manufactured by a photolithography process. An object of another embodiment of the present invention is to provide a highly reliable light-emitting device with a tandem structure and a low operating voltage, which is manufactured by a photolithography process. An object of another embodiment of the present invention is to provide a highly reliable light-emitting device with high emission efficiency, which has a tandem structure and a low operating voltage, and is manufactured by a photolithography process.

[0012] Another object of an embodiment of the present invention is to provide a novel light-emitting device having a tandem structure and suitable for use in a high-resolution display device. Another object of another embodiment of the present invention is to provide a highly efficient light-emitting device having a tandem structure and suitable for use in a high-resolution display device. Another object of an embodiment of the present invention is to provide a light-emitting device having a tandem structure and a low operating voltage and suitable for use in a high-resolution display device.Another object of an embodiment of the present invention is to provide a highly reliable light-emitting device having a tandem structure and usable in a high-resolution display device. Another object of another embodiment of the present invention is to provide a highly reliable light-emitting device with high emission efficiency, having a tandem structure and usable in a high-resolution display device. Another object of another embodiment of the present invention is to provide a highly reliable light-emitting device having a tandem structure and a low operating voltage, usable in a high-resolution display device.An object of another embodiment of the present invention is to provide a highly reliable light-emitting device with high emission efficiency, which has a tandem structure and a low operating voltage and can be used in a high-resolution display device.

[0013] An object of another embodiment of the present invention is to provide a highly reliable display device. An object of another embodiment of the present invention is to provide a display device with low power consumption. An object of another embodiment of the present invention is to provide a high-resolution display device. An object of another embodiment of the present invention is to provide a highly reliable and high-resolution display device. An object of another embodiment of the present invention is to provide a high-resolution display device with low power consumption.

[0014] It should be noted that the description of these objects does not preclude the existence of further objects. An embodiment of the present invention does not necessarily have to fulfill all of these objects. Further objects may be derived from the explanation of the description, the drawings, the claims, and the like.

[0015] One embodiment of the present invention is a light-emitting device among a plurality of light-emitting devices included in a group of light-emitting devices. The group of light-emitting devices includes a first electrode group formed over an insulating surface, a second electrode facing the first electrode group, and a first layer group positioned between the first electrode group and the second electrode. The first electrode group includes a plurality of first electrodes independent of the plurality of light-emitting devices. The first layer group includes a plurality of first layers independent of the plurality of light-emitting devices. The second electrode is a continuous conductive layer shared by the plurality of light-emitting devices.The light-emitting device comprises one of the first electrodes included in the first electrode group, the second electrode, and one of the first layers included in the first layer group. The second electrode and the first layer overlap with the first electrode. The first layer comprises a first light-emitting layer, a second light-emitting layer, and an intermediate layer positioned between the first light-emitting layer and the second light-emitting layer. The intermediate layer comprises a first region containing a first organic compound, a second organic compound, and a metal or a metal oxide. The first organic compound has a first π-electron-deficient heteroaromatic ring having an electron-donor group. The second organic compound has a second π-electron-deficient heteroaromatic ring.A LUMO level of the second organic compound is more than or equal to 0.20 eV lower than a LUMO level of the first organic compound. A distance between the first layer included in the light-emitting device and the first layer included in another light-emitting device adjacent to the light-emitting device is greater than or equal to 0.5 µm and less than or equal to 5 µm.

[0016] Another embodiment of the present invention is the light-emitting device having the above structure, in which, when the LUMO level of the first organic compound is LUMO1 (eV), the LUMO level (LUMO2 (eV)) of the second organic compound satisfies LUMO1 - 0.50 ≤ LUMO2 ≤ LUMO - 0.20.

[0017] Another embodiment of the present invention is the light-emitting device having the above structure, in which, when the LUMO level of the first organic compound is LUMO1 (eV), the LUMO level (LUMO2 (eV)) of the second organic compound satisfies LUMO1 - 0.50 ≤ LUMO2 ≤ LUMO - 0.30.

[0018] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the first π-electron-deficient heteroaromatic ring is a heteroaromatic ring having two or more pyridine rings.

[0019] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein an acid constant pK s of the first organic compound is greater than or equal to 8.

[0020] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein a glass transition temperature of the second organic compound is higher than or equal to 100 °C.

[0021] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the first π-electron-deficient heteroaromatic ring is different from the second π-electron-deficient heteroaromatic ring.

[0022] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the second organic compound has an azole ring (an imidazole ring, a pyrazole ring, an oxazole ring, or a thiazole ring), a triazole ring, a diazine ring (a pyrazine ring, a pyrimidine ring, or a pyridazine ring), or a triazine ring.

[0023] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein an acid constant pK s of the second organic compound is less than 4.

[0024] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the second organic compound has a polarization term δp of less than or equal to 4.0 MPa 0,5 in a solubility parameter δ.

[0025] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the first light-emitting layer is closer to the first electrode than the second light-emitting layer, the first light-emitting layer contains a third organic compound, the third organic compound has a third π-electron-deficient heteroaromatic ring, and the third π-electron-deficient heteroaromatic ring is the same as the second π-electron-deficient heteroaromatic ring.

[0026] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the first light-emitting layer is closer to the first electrode than the second light-emitting layer, the first light-emitting layer contains the third organic compound, and the third organic compound is the same as the second organic compound.

[0027] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein a first electron-transport layer is provided between the first light-emitting layer and the intermediate layer, the first electron-transport layer contains a fourth organic compound, and the fourth organic compound is different from the third organic compound.

[0028] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the metal belongs to any one of Group 1, Group 2, Group 3, Group 11, Group 12 and Group 13.

[0029] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the metal belongs to any one of Group 3, Group 11, Group 12 and Group 13.

[0030] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the first π-electron-deficient heteroaromatic ring comprises a phenanthroline ring.

[0031] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the first π-electron-deficient heteroaromatic ring is a 1,10-phenanthroline ring and the electron donor group is located at a 4-position and / or a 7-position of the 1,10-phenanthroline ring.

[0032] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the electron donor group is one or more of an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group.

[0033] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein an acid constant pK s of the first organic compound is greater than or equal to 8.

[0034] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the minimum value of an electrostatic potential of the first organic compound is less than or equal to -0.085 E h is when a threshold value of the electron density distribution in atomic units is 0.0004 e / a0 3 is.

[0035] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the first organic compound, the second organic compound, and the metal or the metal oxide are mixed in the first region.

[0036] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein a layer containing the metal or the metal oxide and a layer in which the first organic compound and the second organic compound are mixed are stacked in the first region.

[0037] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the layer containing the metal or the metal oxide is positioned between the layer in which the first organic compound and the second organic compound are mixed and the second light-emitting layer.

[0038] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the spin density of the first region measured by an electron spin resonance method is higher than or equal to 5 × 10 16 Spins / cm 3 is.

[0039] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the intermediate layer comprises a second region, the second region is positioned between the first region and the second electrode, and the second region contains the third organic compound having a hole transport property and a first substance having an acceptor property with respect to the third organic compound.

[0040] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein a third region containing a second substance is provided between the first region and the second region.

[0041] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein the spin density of the second region measured by an electron spin resonance method is higher than or equal to 1 × 10 17 Spins / cm 3 is.

[0042] Another embodiment of the present invention is the light-emitting device having any of the above structures, wherein a second layer is provided, and the second layer is shared by the plurality of light-emitting devices and positioned between the first layer and the second electrode.

[0043] Another embodiment of the present invention is a display device comprising one of the above light-emitting devices.

[0044] Another embodiment of the present invention is a display module comprising the above display device and a terminal and / or an integrated circuit.

[0045] Another embodiment of the present invention is an electronic device comprising the above display module and at least one of a housing, a battery, a camera, a speaker, and a microphone.

[0046] According to one embodiment of the present invention, a novel light-emitting device having a tandem structure can be provided. According to another embodiment of the present invention, a highly efficient light-emitting device having a tandem structure can be provided. According to another embodiment of the present invention, a light-emitting device having a tandem structure and a low operating voltage can be provided. According to another embodiment of the present invention, a highly reliable light-emitting device having a tandem structure can be provided. According to another embodiment of the present invention, a highly efficient and highly reliable light-emitting device having a tandem structure can be provided.According to another embodiment of the present invention, a highly reliable light-emitting device with a tandem structure and a low operating voltage can be provided. According to another embodiment of the present invention, a highly efficient and highly reliable light-emitting device with a tandem structure and a low operating voltage can be provided.

[0047] According to another embodiment of the present invention, a novel light-emitting device having a tandem structure and manufactured by a photolithography process can be provided. According to another embodiment of the present invention, a highly efficient light-emitting device having a tandem structure and manufactured by a photolithography process can be provided. According to another embodiment of the present invention, a light-emitting device having a tandem structure and a low operating voltage and manufactured by a photolithography process can be provided. According to another embodiment of the present invention, a highly reliable light-emitting device having a tandem structure and manufactured by a photolithography process can be provided.According to another embodiment of the present invention, a highly reliable light-emitting device with high emission efficiency can be provided, which has a tandem structure and is manufactured by a photolithography process. According to another embodiment of the present invention, a highly reliable light-emitting device with high emission efficiency can be provided, which has a tandem structure and a low operating voltage and is manufactured by a photolithography process. According to another embodiment of the present invention, a highly reliable light-emitting device with high emission efficiency can be provided, which has a tandem structure and a low operating voltage and is manufactured by a photolithography process.

[0048] According to another embodiment of the present invention, a novel light-emitting device having a tandem structure and usable in a high-resolution display device can be provided. According to another embodiment of the present invention, a highly efficient light-emitting device having a tandem structure and usable in a high-resolution display device can be provided. According to another embodiment of the present invention, a light-emitting device having a tandem structure and a low operating voltage and usable in a high-resolution display device can be provided.According to another embodiment of the present invention, a highly reliable light-emitting device having a tandem structure and usable in a high-resolution display device can be provided. According to another embodiment of the present invention, a highly reliable light-emitting device with high emission efficiency can be provided, which has a tandem structure and can be used in a high-resolution display device. According to another embodiment of the present invention, a highly reliable light-emitting device having a tandem structure and a low operating voltage can be provided, which can be used in a high-resolution display device.According to another embodiment of the present invention, there can be provided a highly reliable light-emitting device with high emission efficiency, which has a tandem structure and a low operating voltage and can be used in a high-resolution display device.

[0049] According to another embodiment of the present invention, a highly reliable display device can be provided. According to another embodiment of the present invention, a low-power display device can be provided. According to another embodiment of the present invention, a high-resolution display device can be provided. According to another embodiment of the present invention, a highly reliable and high-resolution display device can be provided. According to another embodiment of the present invention, a low-power high-resolution display device can be provided.

[0050] It should be noted that the description of these effects does not preclude the existence of further effects. An embodiment of the present invention does not necessarily have to exhibit all of these effects. Further effects can be derived from the explanation of the description, the drawings, and the claims. Short description of the drawings

[0051] In the accompanying drawings: Fig. 1 represents a light-emitting device; Fig. 2 represents light-emitting devices; Fig. 3A and Fig. 3B are a plan view and a cross-sectional view of a light-emitting device, respectively; Fig. 4A to Fig. 4E are cross-sectional views illustrating an example of a manufacturing method of a display device; Fig. 5A to Fig. 5D are cross-sectional views illustrating the example of a manufacturing method of a display device; Fig. 6A to Fig. 6D are cross-sectional views illustrating the example of a manufacturing method of a display device; Fig. 7A to Fig. 7C are cross-sectional views illustrating the example of a manufacturing method of a display device; Fig. 8A to Fig. 8C are cross-sectional views illustrating the example of a manufacturing method of a display device; Fig. 9A to Fig. 9C are cross-sectional views illustrating the example of a manufacturing method of a display device; Fig. 10A and Fig. 10B are perspective views illustrating a structural example of a display module; Fig. 11A and Fig. 11B are cross-sectional views showing structural examples of a display device; Fig. 12 is a perspective view showing a structural example of a display device; Fig. 13 is a cross-sectional view showing a structural example of a display device; Fig. 14 is a cross-sectional view showing a structural example of a display device; Fig. 15 is a cross-sectional view showing a structural example of a display device; Fig. 16A to Fig. 16D represent examples of electronic devices; Fig. 17A to Fig. 17F represent examples of electronic devices; Fig. 18A to Fig. 18G are examples of electronic devices; Fig. 19A to Fig. 19C shows results of the analysis of the spin density distribution in composite materials in a ground state; Fig. 20A and Fig. 20B shows results of the analysis of electrostatic potential maps of organic compounds in a ground state; Fig. 21A to Fig. 21C shows results of the analysis of electrostatic potential maps of composite materials in a ground state; Fig. Fig. 22 shows the luminance-current density characteristics of light-emitting devices 1-1 to 1-8; Fig. Fig. 23 shows the luminance-voltage characteristics of the light-emitting devices 1-1 to 1-8; Fig. Fig. 24 shows the current efficiency-current density characteristics of the light-emitting devices 1-1 to 1-8; Fig. Fig. 25 shows the current density-voltage characteristics of the light-emitting devices 1-1 to 1-8; Fig. 26 shows the electroluminescence spectra of the light-emitting devices 1-1 to 1-8; Fig. Fig. 27 shows the current density-voltage characteristics of the light-emitting devices 1-1 to 1-8; Fig. Figure 28 shows a relationship between voltages of the light-emitting devices 1-1 to 1-8 at a current density of 50 mA / cm 2 and the LUMO levels of second organic compounds; Fig. Fig. 29 shows the luminance-current density characteristics of light-emitting devices 2-1 to 2-4; Fig. 30 shows the luminance-voltage characteristics of the light-emitting devices 2-1 to 2-4; Fig. 31 shows the power efficiency-luminance characteristics of the light-emitting devices 2-1 to 2-4; Fig. 32 shows the current density-voltage characteristics of the light-emitting devices 2-1 to 2-4; Fig. 33 shows the electroluminescence spectra of the light-emitting devices 2-1 to 2-4; Fig. 34 shows the luminance-current density characteristics of light-emitting devices 3-1 and 3-2; Fig. 35 shows the luminance-voltage characteristics of the light-emitting devices 3-1 and 3-2; Fig. 36 shows the current efficiency-current density characteristics of the light-emitting devices 3-1 and 3-2; Fig. 37 shows the current density-voltage characteristics of the light-emitting devices 3-1 and 3-2; Fig. 38 shows the electroluminescence spectra of the light-emitting devices 3-1 and 3-2; Fig. 39 shows the time dependence of the normalized luminance of the light-emitting devices 3-1 and 3-2; Fig. Fig. 40 shows the luminance-current density characteristics of light-emitting devices 4-1 to 4-4; Fig. Fig. 41 shows the luminance-voltage characteristics of the light-emitting devices 4-1 to 4-4; Fig. 42 shows the current efficiency-current density characteristics of the light-emitting devices 4-1 to 4-4; Fig. 43 shows the current density-voltage characteristics of the light-emitting devices 4-1 to 4-4; and Fig. Figure 44 shows the electroluminescence spectra of the light-emitting devices 4-1 to 4-4. Detailed description of the invention

[0052] Embodiments will be described in detail with reference to the drawings. It should be noted that the embodiments of the present invention are not limited to the following description, and it will be readily apparent to those skilled in the art that modes and details of the present invention can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as limited to the description of the following embodiments.

[0053] In this specification and the like, a device formed using a metal mask or a fine metal mask (FMM) is sometimes referred to as a device having a metal mask (MM) structure. In this specification and the like, a device formed without using a metal mask or an FMM is sometimes referred to as a device having a metal maskless (MML) structure. (Embodiment 1)

[0054] A tandem light-emitting device comprising a plurality of light-emitting units between a pair of electrodes and an intermediate layer that generates charge carriers between the plurality of light-emitting units can have higher current efficiency than a normal light-emitting device comprising only one light-emitting unit between electrodes.

[0055] The intermediate layer in the tandem light-emitting device includes a charge-generation layer (CGL). The CGL is a layer in which electrons and holes are generated by charge separation caused by the application of a voltage.

[0056] A layer containing a material having a hole-transporting property and a material having an electron-accepting property with respect to the material having a hole-transporting property (P-type CGL), and a layer containing a material having an electron-transporting property and a material having an electron-donating property with respect to the material having an electron-transporting property (N-type CGL) are stacked and used as a CGL, which facilitates the injection of holes or electrons into each light-emitting unit and is preferred to reduce the operating voltage.

[0057] This is because when holes generated in the P-type CGL are injected into a hole transport layer of the light-emitting unit on the cathode side through the material having a hole transport property contained in the P-type CGL, and electrons generated in the N-type CGL are injected into an electron transport layer of the light-emitting unit on the anode side through the material having an electron transport property contained in the N-type CGL, a carrier injection barrier can be reduced.

[0058] A vacuum evaporation method using a metal mask (mask evaporation) is widely used as a method for forming an organic compound film in a predetermined shape at a predetermined position. However, in recent years, density and resolution have increased; therefore, the resolution improvement in mask evaporation is almost at its peak due to problems, typically a problem with the degree of alignment accuracy and a problem with the arrangement interval of the substrate and the mask.

[0059] In contrast, photolithography is a processing method that allows for finer patterning than mask evaporation. Furthermore, since photolithography easily achieves large-area processing, processing an organic compound film using photolithography instead of mask evaporation is being explored. However, processing an organic compound film using photolithography has a problem inherent in a light-emitting device.

[0060] As described above, it is known that when a light-emitting device is exposed to atmospheric components such as water and oxygen, initial characteristics and reliability are affected, and it is therefore common knowledge that the light-emitting device is treated in a near-vacuum atmosphere.

[0061] In particular, an electron injection layer in a light-emitting device and an N-type CGL of an intermediate layer used in a tandem light-emitting device are of note. The electron injection layer and the N-type CGL each typically contain a material having a donor property with respect to an electron-transport material, typically an alkali metal, an alkaline earth metal, or a compound thereof (hereinafter also referred to as an alkali metal compound or the like), for generating electrons. The alkali metal compound or the like is highly reactive with water or oxygen and therefore deteriorates rapidly, not only when exposed directly to the air but also when exposed to the air via a plurality of organic compound layers. As a result, the function as the electron injection layer and the intermediate layer is lost.

[0062] However, processing steps by the aforementioned photolithography technique inevitably expose the surface of the EL layer to air. Therefore, processing by the photolithography technique causes a significant deterioration in the electron injection properties of an electron injection layer and an intermediate layer using an alkali metal compound or the like. Therefore, a light-emitting device including an electron injection layer and / or an intermediate layer formed using an alkali metal compound or the like and processed by a photolithography technique exhibits reduced emission efficiency or increased operating voltage, and it is difficult to obtain favorable properties.

[0063] For this problem, thanks to the structure of an EL layer of a light-emitting device (in the case of a so-called face-up stacked element in which an electron injection layer is formed after the formation of a light-emitting layer), an electron injection layer can be formed after processing with a photolithography technique and therefore avoid the influence of the processing.

[0064] Meanwhile, in a tandem light-emitting device, when a light-emitting layer of a light-emitting unit on the cathode side is processed by a photolithography technique, an intermediate layer in contact with the anode side of the light-emitting unit is inevitably subjected to processing. For this reason, it is difficult to obtain favorable properties in a tandem light-emitting device including an intermediate layer with the N-type CGL formed using an alkali metal compound or the like while processing by a photolithography technique.

[0065] Here, the inventors of the present invention have found that a tandem light-emitting device having advantageous characteristics can also be obtained by a photolithography process comprising exposing an EL layer to air by using, instead of a conventional N-type CGL of an intermediate layer, a layer containing a metal or a metal oxide, an organic compound having a first π-electron-deficient heteroaromatic ring having an electron-donor group, and an organic compound having a second π-electron-deficient heteroaromatic ring.

[0066] That is, when a region (a first region) containing the metal or the metal oxide, the organic compound (a first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donor group, and the organic compound (a second organic compound) having the second π-electron-deficient heteroaromatic ring is provided instead of a conventional N-type CGL of an intermediate layer, a tandem light-emitting device having advantageous characteristics can be obtained even if it is fabricated by a photolithography process including exposing an EL layer to air.

[0067] In one embodiment of the present invention, the LUMO level of the second organic compound is lower than that of the first organic compound preferably by more than or equal to 0.20 eV and less than or equal to 0.50 eV, more preferably by more than or equal to 0.25 eV and less than or equal to 0.50 eV, even more preferably by more than or equal to 0.30 eV and less than or equal to 0.50 eV, even more preferably by more than or equal to 0.35 eV and less than or equal to 0.50 eV, even more preferably by more than or equal to 0.40 eV and less than or equal to 0.50 eV.

[0068] This means that if the LUMO level of the first organic compound is “LUMO1 (eV)” and the LUMO level of the second organic compound is “LUMO2 (eV)”, the LUMO2 preferentially satisfies the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.20

[0069] Preferably, the LUMO2 fulfills the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.25

[0070] Preferably, the LUMO2 fulfills the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.30

[0071] Preferably, the LUMO2 fulfills the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.35

[0072] Preferably, the LUMO2 fulfills the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.40

[0073] When the LUMO2 is within any of the above ranges, the light-emitting device of one embodiment of the present invention can be a tandem light-emitting device that has advantageous characteristics and a low operating voltage regardless of whether a photolithography process involving exposure of an EL layer to air is performed. Furthermore, the tandem light-emitting device can have high reliability.

[0074] The metal or metal oxide, the first organic compound, and the second organic compound form a donor level (SOMO level or HOMO level) when they interact with each other. This lowers the barrier to electron injection into an electron-transport layer, allowing electrons generated in the intermediate layer to be easily injected and transported to the electron-transport layer without using a conventional N-type CGL, which degrades significantly when subjected to a photolithography process involving exposure to air. Furthermore, the presence of LUMO2 in any of the above regions enables the interaction to become more stable, allowing the formation of an intermediate layer that is not easily degraded even when subjected to a photolithography process involving exposure to air.Therefore, electrons generated in the intermediate layer can be smoothly injected and transported to the adjacent electron transport layer even when a photolithography process involving exposure of an EL layer to air is performed, so that a highly reliable tandem light-emitting device with a suppressed increase in operating voltage can be fabricated by a photolithography process.

[0075] It should be noted that the HOMO level and LUMO level of an organic compound are generally estimated by cyclic voltammetry (CV), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoemission spectroscopy, or the like. When comparing values ​​of different compounds, it is preferable to use values ​​estimated using the same measurement.

[0076] As described above, when an intermediate layer is formed using the organic compound (the first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donating group, the organic compound (the second organic compound) having the second π-electron-deficient heteroaromatic ring, and the metal or the metal oxide, the intermediate layer can exhibit resistance to oxygen and water in the air, as well as to water and a chemical solution used in the photolithography process. Therefore, an embodiment of the present invention can provide a light-emitting device with high moisture resistance, high water resistance, high oxygen resistance, high chemical resistance, low driving voltage, and high emission efficiency.

[0077] The region (the first region) containing the organic compound (the first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donor group, the organic compound (the second organic compound) having the second π-electron-deficient heteroaromatic ring, and the metal or the metal oxide may be either a mixed layer of the first organic compound, the second organic compound, and the metal or the metal oxide, or a layer arrangement of a layer containing the metal or the metal oxide and a layer containing the first organic compound and the second organic compound.In the case where the first region is the layer arrangement of the layer containing the metal or the metal oxide and the layer containing the first organic compound and the second organic compound, it is preferable that the layer containing the metal or the metal oxide and the layer containing the first organic compound and the second organic compound are arranged on the cathode side and the anode side, respectively, to be in contact with each other, and that the layer containing the first organic compound and the second organic compound is in contact with a light-emitting unit on the anode side.

[0078] When the first region is the mixed layer of the first organic compound, the second organic compound, and the metal or the metal oxide, it can have a smaller number of layers than the layered assembly, and therefore it is highly productive and can be easily produced in large quantities.

[0079] A tandem light-emitting device comprising a conventional N-type CGL formed using an alkali metal, an alkaline earth metal, or an oxide thereof, such as lithium oxide (Li2O), exhibits advantageous properties when fabricated by a continuous vacuum process (without exposure to air). On the other hand, as described above, when fabricated by a photolithography process that includes exposing an EL layer to air, the tandem light-emitting device exhibits a much higher operating voltage than a light-emitting device fabricated by a continuous vacuum process. This is likely because, as described above, an alkali metal, an alkaline earth metal, or an oxide thereof deteriorates due to exposure to air, and the donor property decreases.

[0080] In one embodiment of the present invention, the alkali metal, the alkaline earth metal, or the oxide thereof, such as lithium oxide (Li2O), the organic compound (the first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donating group, and the organic compound (the second organic compound) having the second π-electron-deficient heteroaromatic ring are used for an intermediate layer of a light-emitting device; therefore, even if the light-emitting device is manufactured by a photolithography process including exposure to air, it can have advantageous properties comparable to those of a light-emitting device manufactured by a continuous vacuum process.

[0081] This is because when the alkali metal, the alkaline earth metal, or the oxide thereof, the organic compound (the first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donor group, and the organic compound (the second organic compound) having the second π-electron-deficient heteroaromatic ring are used for the first region, a donor level (SOMO level or HOMO level) is formed by their interaction, and the absolute value of the stabilization energy of the interaction is large and the donor level is high, which can reduce the barrier to electron injection from the intermediate layer to the electron-transport layer even after exposure to air, and enable smooth injection and transport of electrons generated in the intermediate layer to the electron-transport layer.Therefore, a tandem light-emitting device can be obtained which has advantageous characteristics and suppressed increase in operating voltage even when exposure to air is performed.

[0082] As described above, by using the first region containing the metal or the metal oxide, the organic compound (the first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donating group, and the organic compound (the second organic compound) having the second π-electron-deficient heteroaromatic ring instead of a conventional N-type CGL, the tandem light-emitting device of one embodiment of the present invention can have advantageous properties even when fabricated by a process including exposing an EL layer to air. That is, using the structure of one embodiment of the present invention provides a tandem light-emitting device with advantageous properties fabricated by a photolithography technique including exposing an EL layer to air.As a result, a display device with very high resolution and advantageous properties can be provided.

[0083] Therefore, when the region (the first region) containing the metal or the metal oxide, the organic compound (the first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donating group, and the organic compound (the second organic compound) having the second π-electron-deficient heteroaromatic ring is provided instead of a conventional N-type CGL of an interlayer of a tandem light-emitting device, the tandem light-emitting device can easily have advantageous properties even if it is manufactured by an air exposure process.

[0084] The light-emitting device of one embodiment of the present invention is a tandem light-emitting device comprising the above-described first region in its intermediate layer. The intermediate layer preferably comprises a second region that is a P-type CGL. A third region may be provided between the first region and the second region. The formation of the third region, for example, allows electrons to be smoothly transferred between the first region and the second region to reduce the operating voltage and reduces interactions between the first region and the second region to improve reliability. <<erster Bereich> >

[0085] As described above, the first region is provided in a region of the intermediate layer on the anode side and contains the metal or metal oxide, the organic compound (the first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donor group, and the organic compound (the second organic compound) having the second π-electron-deficient heteroaromatic ring. The first region is in contact with a light-emitting unit on the anode side. <Metall oder Metalloxid>

[0086] As the metal or metal oxide contained in the first region, an alkali metal (a Group 1 element) such as Li, an alkaline earth metal (a Group 2 element) such as Mg or Ca, a Group 3 element including Y and lanthanides such as Eu and Yb, a Group 11 element such as Cu, Ag or Au, a Group 12 element such as Zn, an earth metal (a Group 13 element) such as Al or In, a Group 14 element such as Sn, or an oxide of any of these metals and elements can be used.

[0087] An alkali metal, an alkaline earth metal, or an oxide thereof is preferably used as the metal or metal oxide. In this case, the donor level formed by interaction with the first and second organic compounds can be a high energy level, and consequently, electrons generated in the intermediate layer can be easily injected into and transported to the electron-transport layer, enabling the light-emitting device to have a low operating voltage and emit light with high emission efficiency. A transition metal and an oxide thereof are preferred because they have low reactivity with air components such as water and oxygen.Among the above materials, a metal belonging to an odd-numbered group (Group 1, 3, 11 or 13) of the periodic table or an oxide thereof is preferably used, in which case a donor level is easily formed by facilitated interaction with the first and second organic compounds.

[0088] A metal or metal oxide that has a low melting point and can be deposited by a vacuum evaporation method is preferably used because it can be easily mixed or stacked with an organic compound. In particular, for example, the metals belonging to Groups 11 and 13 and their oxides have low melting points and are therefore suitable for vacuum evaporation. The metals belonging to Groups 11 and 13 and their oxides are preferred because they are stable with respect to oxygen and water in the air.The metal or metal oxide that can be deposited by a vacuum evaporation method preferably has a melting point under normal pressure of less than or equal to 2000 °C, more preferably less than or equal to 1500 °C, even more preferably less than or equal to 1000 °C, or a sublimation temperature under reduced pressure (vacuum of 1 Pa or lower) of less than or equal to 1500 °C, more preferably less than or equal to 1000 °C, even more preferably less than or equal to 500 °C.

[0089] Specifically, as the metal or metal oxide, lithium, magnesium, calcium, silver, zinc, indium, an oxide thereof, or the like can be used. Note that even if a metal is used alone, the metal may be oxidized in a deposition step or an air exposure step to become a metal oxide.

[0090] In particular, lithium, magnesium, calcium, ytterbium, silver, zinc, aluminum, indium or the like is particularly preferred as such a metal material. <erste organische Verbindung>

[0091] As the first organic compound contained in the first region, an organic compound having a π-electron-deficient heteroaromatic ring can be used. The π-electron-deficient heteroaromatic ring of the organic compound used as the first organic compound preferably has an electron-donor group, in which case the electron density of the π-electron-deficient heteroaromatic ring can be high.

[0092] An organic compound having a heteroaromatic ring containing nitrogen is preferred as an organic compound having a π-electron-deficient heteroaromatic ring. A pyridine ring is preferred as a heteroaromatic ring containing nitrogen. An organic compound having a heteroaromatic ring containing two or more pyridine rings is particularly preferred as an organic compound having a π-electron-deficient heteroaromatic ring. This is because two nitrogen atoms contained in the organic compound having the heteroaromatic ring with two or more pyridine rings are coordinated to a metal or a metal oxide to facilitate interaction with the metal or metal oxide.

[0093] Among organic compounds having a heteroaromatic ring with two or more pyridine rings, an organic compound having a bipyridine skeleton whose nitrogen atoms are more easily coordinated to a metal or a metal oxide is particularly preferably used to facilitate interaction with the metal or the metal oxide. A phenanthroline ring, which is rigid and stable, is more preferably used. In particular, an organic compound having a 1,10-phenanthroline ring whose two nitrogen atoms are positioned to be easily coordinated to a metal or a metal oxide is preferably used to facilitate interaction with the metal or the metal oxide.

[0094] In the case where electron donor groups are introduced into a 1,10-phenanthroline ring, the electron donor groups are preferably bonded at the 4- and 7-positions of the 1,10-phenanthroline ring. By introducing electron donor groups into the 4- and 7-positions of the 1,10-phenanthroline ring, the electron density of the nitrogen atoms at the 1- and 10-positions can be increased, thereby facilitating interaction with the metal or metal oxide.

[0095] Examples of the electron-donating group contained in the π-electron-deficient heteroaromatic ring include an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group. Note that an electron-donating group preferably introduced into the π-electron-deficient heteroaromatic ring is not limited to these examples. Any group that can increase the electron density of the π-electron-deficient heteroaromatic ring when introduced therein can be used as the electron-donating group. The electron-donating group can be introduced into the π-electron-deficient heteroaromatic ring via an arylene group, such as a phenylene group, and the arylene group is preferably a p-phenylene group.

[0096] Specific examples of the alkyl group that can be used as the electron donor group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, a hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a neohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group, and a 2,3-dimethylbutyl group.

[0097] Specific examples of the alkoxyl group that can be used as an electron donor group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, an isobutoxy group, a tert-butoxy group, an n-pentyloxy group, an isopentyloxy group, a sec-pentyloxy group, a tert-pentyloxy group, a neopentyloxy group, an n-hexyloxy group, an isohexyloxy group, a sec-hexyloxy group, a tert-hexyloxy group, and a neohexyloxy group.

[0098] Specific examples of the aryloxy group that can be used as an electron donor group include a phenoxy group, an o-tolyloxy group, an m-tolyloxy group, a p-tolyloxy group, a mesityloxy group, an o-biphenyloxy group, an m-biphenyloxy group, a p-biphenyloxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, and a 2-fluorenyloxy group. Note that the aryloxy group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0099] Specific examples of the alkylamino group that can be used as an electron donor group include a dimethylamino group and a diethylamino group.

[0100] Specific examples of the arylamino group that can be used as an electron donor group include a diphenylamino group, a bis(α-naphthyl)amino group, and a bis(m-tolyl)amino group. Note that the arylamino group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0101] Specific examples of the heterocyclic amino group that can be used as an electron donor group include groups represented by the following structural formulas (R-1) to (R-26). Note that the heterocyclic amino group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0102] Note that the group represented by the structural formula (R-1), (R-2), (R-3), (R-4), (R-5), (R-8), (R-9), (R-10), (R-12), (R-14), (R-15), (R-16), (R-17), or (R-21) is more preferably used as the electron-donating group. Among these groups, the group represented by the structural formula (R-3), (R-4), (R-8), or (R-21) is preferably used because the group has a high electron-donating property and can further increase the electron density of the phenanthroline ring.

[0103] Concrete examples of the electron donor group include groups represented by the following structural formulas (R-27) and (R-28).

[0104] Note that an organic compound having a π-electron-deficient heteroaromatic ring that can be used as the first organic compound may have both the above-described electron-donating group and another substituent. Specific examples of the substituent that can be introduced into the π-electron-deficient heteroaromatic ring together with the above-described electron-donating group include an aryl group. Specific examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a mesityl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a 1-naphthyl group, a 2-naphthyl group, and a 2-fluorenyl group. It should be noted that the aryl group may further have a substituent, and concrete examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0105] Specific examples of the organic compound having a π-electron-deficient heteroaromatic ring that can be used as the first organic compound are represented by structural formulas (100) to (110). Note that the organic compound that can be used as the first organic compound is not limited to these examples.

[0106] The negative minimum value of the electrostatic potential (ESP) of the first organic compound is preferably small (ie the minimum value is preferably a negative value whose absolute value is large), in which case the absolute value of the stabilization energy of the interaction with the metal or the metal oxide is large.

[0107] In an organic compound containing a π-electron-deficient heteroaromatic ring, the electrostatic potential around the heteroatoms of the π-electron-deficient heteroaromatic ring, which is likely to be negative, can be further reduced (i.e., the absolute value of the negative value can be increased) by introducing an electron-donating group into the π-electron-deficient heteroaromatic ring.

[0108] It should be noted that an electrostatic potential is the energy of the interaction between a positive point charge carrying a unit amount of current and the electron distribution of a molecule. The electrostatic potential value also depends on the threshold electron density.

[0109] In order to increase the efficiency of the interaction with the metal or metal oxide, the minimum value of the electrostatic potential of the first organic compound is preferably smaller (negatively larger) than the minimum value of the electrostatic potential of a π-electron-deficient heteroaromatic ring without substituents.

[0110] In particular, if the threshold value of the electron density distribution in atomic units is 0.0004 e / a0 3 (e represents the elementary charge (1 e = 1.60218 × 10 -19 C) and a0 represents the Bohr radius (1 a0 = 5.29177 × 10 -11 m) is, the minimum value of the electrostatic potential of the first organic compound is preferably less than or equal to -0.085 E h (E h represents the Hartree energy (1 E h = 27.211 eV), preferably less than or equal to -0.090 E h . If the threshold value of the electron density distribution in atomic units is 0.003 e / a03 the minimum value of the electrostatic potential of the first organic compound is preferably less than or equal to -0.12 E h , preferably less than or equal to -0.13 E h . The minimum value of the ESP of the first organic compound is preferably less than or equal to -0.085 E h , if the threshold value of the electron density distribution in atomic units is 0.0004 e / a0 3 is, preferably less than or equal to -0.12 E h , if the threshold value of the electron density distribution in atomic units is 0.003 e / a0 3 is.

[0111] The minimum electrostatic potential (ESP) values ​​of the organic compounds represented by the above structural formulas (100) to (107), which can be used as the first organic compound, BPhen, mPPhen2P, NBPhen, Phen, and Hid2Phen, were estimated by quantum chemical calculation. The structural formulas (100) to (107) and the structural formulas of BPhen, mPPhen2P, NBPhen, Phen, and Hid2Phen are shown below.

[0112] Gaussian 09 was used as the quantum chemical calculation program. The calculations were performed using an SGI 8600, manufactured by Hewlett Packard Enterprise. The most stable structures of the organic compounds in a ground state were calculated using density functional theory (DFT). 6-311G(d,p) was used as the basis function, and B3LYP was used as the functional.

[0113] Table 1 shows the analysis results of the electrostatic potentials of organic compounds in the ground state. Note that the electrostatic potential is the energy of interaction between a positive point charge with a unit amount of current and the electron distribution of a molecule. The electrostatic potential value also depends on the threshold electron density. Table 1 shows the electrostatic potentials in the electron density distribution at the time when the threshold electron density is 0.0004 e / a0 in atomic units. 3 or 0.003 e / a0 3 is. [Table 1] Minimum value of ESP (E h ) (Threshold value of density = 0.0004 e / a0 3 ) Minimum value of ESP (E h ) (Threshold value of density = 0.003 e / a0 3 ) Pyrrd-Phen (100) -0,091 -0,12 DMeAPhen (101) -0,089 -0,12 p-MeO-Phen (102) -0,089 -0,12 4,7hpp2Phen (103) -0,096 -0,13 CzPhen (104) -0,072 -0,10 mhppPhen2P (105) -0,057 -0,096 9Ph2hppPhen (106) -0,057 -0,096 2,9hpp2Phen (107) -0,061 -0,097 BPhen -0,083 -0,11 mPPhen2P -0,057 -0,094 NBPhen -0,053 -0,093 Phen -0,081 -0,110 Hid2Phen -0,094 -0,13

[0114] From the above table, it is found that the minimum values ​​of ESP of the organic compounds represented by the structural formulas (100) to (103) and Hid2Phen are each less than or equal to -0.085 E hare when the threshold value of the electron density distribution in atomic units is 0.0004 e / a0 3 and that these organic compounds are more preferably used as the first organic compound. It is also found that the minimum values ​​of ESP of the organic compounds represented by structural formulas (100) to (103) and Hid2Phen are each less than or equal to -0.12 E h are when the threshold value of the electron density distribution in atomic units is 0.003 e / a0 3 and that these organic compounds are preferably used as the first organic compound.

[0115] This is because the organic compounds represented by structural formulas (100) to (103) and Hid2Phen have an electron donor group at each of the 4- and 7-positions of the 1,10-phenanthroline ring and therefore have a good property of donating electrons to the nitrogen atoms at the 1- and 10-positions of the phenanthroline ring.

[0116] It is found that the minimum values ​​of ESP of the organic compounds represented by the structural formulas (101) and (103) and Hid2Phen are respectively less than or equal to -0.090 E h are when the threshold value of the electron density distribution in atomic units is 0.0004 e / a0 3and that these organic compounds are particularly preferably used as the first organic compound. It is also found that the minimum values ​​of ESP of the organic compound represented by the structural formula (103) and Hid2Phen are each less than or equal to -0.13 E h are when the threshold value of the electron density distribution in atomic units is 0.003 e / a0 3 and that these organic compounds are particularly preferably used as the first organic compound.

[0117] It is found that the organic compound represented by the structural formula (103) and Hid2Phen are more preferably used as the first organic compound because their minimum values ​​of ESP are respectively less than or equal to -0.090 E h are when the threshold value of the electron density distribution in atomic units is 0.0004 e / a0 3 and less than or equal to -0.13 E hare when the threshold value of the electron density distribution in atomic units is 0.003 e / a0 3 is.

[0118] The first organic compound is preferably strongly basic, in which case the first organic compound interacts with holes to greatly reduce the hole transport property in the first region of the intermediate layer, which enables the light-emitting device to have high efficiency and a low operating voltage. In particular, the acid constant pK s of the first organic compound is preferably greater than or equal to 8, more preferably greater than or equal to 10, even more preferably greater than or equal to 12.

[0119] In the case where the acid constant pK s of an organic compound is unknown, the acid constants pK s of the frameworks in the organic compound, and the largest acid constant pK scan be used as acid constant pK s the organic compound.

[0120] The acid constant can be determined by calculation. For example, the acid constant pK s can be determined using the following calculation method.

[0121] The initial structure of a molecule used as a computational model is the most stable structure (the singlet ground state) determined from an ab initio calculation.

[0122] Jaguar, the quantum chemical computing software developed by Schrödinger, Inc., is used for the ab initio calculation, and the most stable structure in the singlet ground state is calculated using density functional theory (DFT). 6-31G is used as the basis function. **is used, and B3LYP-D3 is used as the functional. The structure subjected to quantum chemical calculation is sampled by a conformational analysis in mixed-torsional / low-mode sampling using Maestro GUI, manufactured by Schrödinger, Inc.

[0123] When calculating pK s One or more atoms in each molecule are identified as basic sites, MacroModel is used to search for the stable structure of the protonated molecule in water, a conformational search is performed using an OPLS2005 force field, and a conformational isomer with the lowest energy is used. The pK s -calculation module from Jaguar. After the structural optimization by B3LYP / 6-31G * has been carried out, a single point calculation is carried out by cc-pVTZ(+), and the pK s-value is calculated using an empirical correction for the functional group(s). In the case where one or more atoms are determined to be basic sites in a molecule, the largest value among the determined values ​​is used as the pK s -value is used. The determined pK s -values ​​are shown below.

[0124] The acid constant pK s of 2,9hpp2Phen is 13.35, that of 4,7hpp2Phen is 13.42, that of Pyrrd-Phen is 11.23, that of mPPhen2P is 5.16, that of NBPhen is 5.59, and that of BPhen is 5.62. <Schätzung der Wechselwirkung zwischen dem Metall und der organischen Verbindung durch die quantenchemische Berechnung>

[0125] The spin density and electrostatic potential (ESP) in the interaction between a metal, the first organic compound containing a π-electron-deficient heteroaromatic ring with an electron-donating group, and the second organic compound containing a π-electron-deficient heteroaromatic ring were analyzed by quantum chemical calculation. The calculation was performed using 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviation: Pyrrd-Phen) as the first organic compound, 11-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 11mDBtBPPnfpr) as the second organic compound, and silver (Ag) as the metal.

[0126] Gaussian 09 was used as the quantum chemical calculation program. The calculations were performed using the SGI 8600, manufactured by Hewlett Packard Enterprise. The most stable structures of the first organic compound alone in a ground state, the second organic compound alone in a ground state, a composite material composed of the first organic compound and the metal in a ground state, a composite material composed of the second organic compound and the metal in a ground state, and a composite material composed of the first organic compound, the second organic compound, and the metal in a ground state were calculated using density functional theory (DFT). 6-311 G(d,p) and LanL2DZ were used as the basis functions, and B3LYP was used as the functional.In DFT, the total energy is represented as the sum of the potential energy, the electrostatic energy between electrons, the electronic kinetic energy, and the exchange-correlation energy, including all complex interactions between electrons. In DFT, an exchange-correlation interaction is also approximated by a functional (a function of another function) of an electron potential with respect to the electron density to enable calculations with high accuracy.

[0127] Fig. 19A to Fig. Figure 19C shows the analysis results of the spin density distribution in the composite material of the first organic compound (pyrr-phen) and the metal (Ag) in a ground state, the composite material of the second organic compound (11mDBtBPPnfpr) and the metal (Ag) in a ground state, and the composite material of the first organic compound (pyrr-phen), the second organic compound (11mDBtBPPnfpr), and the metal (Ag) in a ground state, respectively. In the diagrams, spheres represent atoms contained in the compounds, and clouds around some of the atoms represent the spin density distribution at the time when the density value in atomic units was 0.003 e / a0 3The clouds represent the localization of the doublet ground state of the compounds. Note that no spin density distribution is observed in the first organic compound (Pyrrd-Phen) in a ground state and the second organic compound (11mDBtBPPnfpr) in a ground state, since the ground states of the first organic compound and the second organic compound are singlet ground states.

[0128] In the composite material of the first organic compound (pyrr-phen) and the metal (Ag) in the doublet ground state, the first organic compound (pyrr-phen) interacts with the metal (Ag), and the metal (Ag) is coordinated to the nitrogen atoms with unshared electron pairs (the nitrogen atoms (N) at the 1- and 10-positions) in the 1,10-phenanthroline ring of the first organic compound (pyrr-phen), which leads to the stabilization and formation of the composite material. As in Fig. Accordingly, as shown in Figure 19A, some spins, due to an unpaired electron of the metal (Ag), are distributed over part of the 1,10-phenanthroline ring of the first organic compound (pyrr-phen), particularly the nitrogen atoms with unshared electron pairs (the nitrogen atoms (N) at the 1- and 10-positions). However, the interaction is weak, and therefore most of the spins are distributed over the metal (Ag).

[0129] In the composite material of the second organic compound (11mDBtBPPnfpr) and the metal (Ag) in the doublet ground state, the second organic compound (11mDBtBPPnfpr) interacts with the metal (Ag), and the metal (Ag) is coordinated to the nitrogen atoms (N) with unshared electron pairs in the phenanthro[9',10':4,5]furo[2,3-b]pyrazine ring of the second organic compound (11mDBtBPPnfpr), which leads to the stabilization and formation of the composite material. As in Fig. Accordingly, as shown in Figure 19B, some spins, due to an unpaired electron of the metal (Ag), are distributed over part of the phenanthro[9',10':4,5]furo[2,3-b]pyrazine ring of the second organic compound (11mDBtBPPnfpr), particularly the nitrogen atoms (N) with unshared electron pairs. However, the interaction is weak, and therefore most of the spins are distributed over the metal (Ag).

[0130] In contrast, in the composite material of the first organic compound (Pyrrd-Phen), the second organic compound (11mDBtBPPnfpr) and the metal (Ag), which is an embodiment of the present invention, in the doublet ground state, the first organic compound (Pyrrd-Phen), the second organic compound (11mDBtBPPnfpr) and the metal (Ag) interact with each other, and the metal (Ag) is coordinated to the nitrogen atoms with unshared electron pairs (the nitrogen atoms (N) at the 1- and 10-positions) in the 1,10-phenanthroline ring of the first organic compound (Pyrrd-Phen) and the nitrogen atoms (N) with unshared electron pairs in the phenanthro[9',10':4,5]furo[2,3-b]pyrazine ring of the second organic compound (11mDBtBPPnfpr), which contributes to the stabilization and formation of the composite material. As in Fig. Accordingly, as shown in Figure 19C, spins due to an unpaired electron of the metal (Ag) are localized in the second organic compound (11mDBtBPPnfpr). Furthermore, no spin density distribution is observed in the metal (Ag). Therefore, the second organic compound (11mDBtBPPnfpr) is found to be in a radical-anion state due to the interaction between the first organic compound (pyrr-phen), the second organic compound (11mDBtBPPnfpr), and the metal (Ag).

[0131] Show next Fig. 20A, Fig. 20B and Fig. 21A to Fig. Figure 21C shows the analysis results of the electrostatic potential maps of the first organic compound (pyrr-phen) in a ground state, the second organic compound (11mDBtBPPnfpr) in a ground state, the composite material of the first organic compound (pyrr-phen) and the metal (Ag) in a ground state, the composite material of the second organic compound (11mDBtBPPnfpr) and the metal (Ag) in a ground state, and the composite material of the first organic compound (pyrr-phen), the second organic compound (11mDBtBPPnfpr), and the metal (Ag) in a ground state, respectively. In the diagrams, spheres represent atoms contained in the compounds, and clouds around some of the atoms represent electrostatic potentials in the electron density distribution at the time when the threshold value of the electron density distribution in atomic units is 0.0004 e / a0 3An electrostatic potential is the energy of the interaction between a positive point charge with a unit amount of current and an electron distribution of a molecule. An electrostatic potential map represents an electrostatic potential on an electron density isosurface using colors. In the map, an area with a negative electrostatic potential is represented by red, an area with a positive electrostatic potential is represented by blue, an atom in the area with a negative electrostatic potential has a negative charge, and an atom in the area with a positive electrostatic potential has a positive charge. To distinguish an area with a negative electrostatic potential and an area with a positive electrostatic potential in Fig. 20A, Fig. 20B and Fig. 21A to Fig. 21C, which are grayscale images, a deep red portion (i.e., the area with a negative electrostatic potential) is surrounded by a thick dotted line, and a deep blue portion (i.e., the area with a positive electrostatic potential) is surrounded by a thin dash-dotted line.

[0132] As in Fig. As shown in Figure 20A, the electrostatic potential around the nitrogen atoms with unshared electron pairs (the nitrogen atoms (N) at the 1- and 10-positions) in the 1,10-phenanthroline ring of the first organic compound (pyrr-phen) is negative in the singlet ground state. The N atoms each exhibited a negative Mulliken partial charge of -0.29 e in atomic units. Consequently, the N atoms are determined to have a negative partial charge.

[0133] As in Fig. As shown in Figure 20B, the electrostatic potential around the nitrogen atoms (N) with unshared electron pairs in the phenanthro[9',10':4,5]furo[2,3-b]pyrazine ring of the second organic compound (11mDBtBPPnfpr) is negative in the singlet ground state. The N atoms each exhibited a negative Mulliken partial charge of -0.31 e in atomic units. Consequently, the N atoms are found to have a negative partial charge.

[0134] In the composite material of the first organic compound (pyrr-phen) and the metal (Ag) in the doublet ground state, the first organic compound (pyrr-phen) interacts with the metal (Ag), and the metal (Ag) is coordinated to the nitrogen atoms with unshared electron pairs (the nitrogen atoms (N) at the 1- and 10-positions) in the 1,10-phenanthroline ring of the first organic compound (pyrr-phen), which leads to the stabilization and formation of the composite material. As in Fig. Accordingly, as shown in Figure 21A, the electrostatic potential around the nitrogen atoms with unshared electron pairs (the nitrogen atoms (N) at the 1- and 10-positions) in the 1,10-phenanthroline ring of the first organic compound (pyrr-phen) and the metal (Ag) is negative. The N atoms each had a negative Mulliken partial charge of -0.37 e in atomic units, and the metal (Ag) had a negative Mulliken partial charge of -0.18 e in atomic units. Consequently, the N atoms and the Ag atom are found to have a negative partial charge.

[0135] In the composite material of the second organic compound (11mDBtBPPnfpr) and the metal (Ag) in the doublet ground state, the second organic compound (11mDBtBPPnfpr) interacts with the metal (Ag), and the metal (Ag) is coordinated to the nitrogen atoms (N) with unshared electron pairs in the phenanthro[9',10':4,5]furo[2,3-b]pyrazine ring of the second organic compound (11mDBtBPPnfpr), which leads to the stabilization and formation of the composite material. As in Fig. Accordingly, as shown in Figure 21B, the electrostatic potential around the nitrogen atoms (N) with unshared electron pairs in the phenanthro[9',10':4,5]furo[2,3-b]pyrazine ring of the second organic compound (11mDBtBPPnfpr) and the metal (Ag) is negative. The N atoms each exhibited a negative Mulliken partial charge of -0.38 e in atomic units, and the metal (Ag) exhibited a negative Mulliken partial charge of -0.09 e in atomic units. Consequently, the N atoms and the Ag atom are found to have a negative partial charge.

[0136] In contrast, in the composite material of the first organic compound (Pyrrd-Phen), the second organic compound (11mDBtBPPnfpr) and the metal (Ag), which is an embodiment of the present invention, in the doublet ground state, the first organic compound (Pyrrd-Phen), the second organic compound (11mDBtBPPnfpr) and the metal (Ag) interact with each other, and the metal (Ag) is coordinated to the nitrogen atoms with unshared electron pairs (the nitrogen atoms (N) at the 1- and 10-positions) in the 1,10-phenanthroline ring of the first organic compound (Pyrrd-Phen) and the nitrogen atoms (N) with unshared electron pairs in the phenanthro[9',10':4,5]furo[2,3-b]pyrazine ring of the second organic compound (11mDBtBPPnfpr), which contributes to the stabilization and formation of the composite material. As in Fig. Accordingly, as shown in Figure 21C, a positive electrostatic potential is distributed mainly between the metal (Ag) and the first organic compound (pyrr-phen), and a negative electrostatic potential is distributed mainly between the second organic compound (11mDBtBPPnfpr). It is also observed that the electrostatic potential around the nitrogen atoms (N) with unshared electron pairs in the phenanthro[9',10':4,5]furo[2,3-b]pyrazine ring of the second organic compound (11mDBtBPPnfpr) is negative, while the electrostatic potential around the metal (Ag) is positive. The N atoms each had a negative Mulliken partial charge of -0.62 e in atomic units, while the metal (Ag) had a positive Mulliken partial charge of 0.37 e in atomic units. These results show that the charge of the Ag atom is distributed over the N atoms.

[0137] From the above, it is found that the metal, the first organic compound having a π-electron-deficient heteroaromatic ring with an electron-donor group, and the second organic compound having a π-electron-deficient heteroaromatic ring are a combination such that the first organic compound and the metal interact with each other to form a donor level and serve as an electron donor with respect to the second organic compound.In one embodiment of the present invention, the intermediate layer formed using the material containing this combination can have a favorable electron injection property and resistance to oxygen and water in the air, as well as water and a chemical solution used during the process by a lithography method; therefore, the light-emitting device can have a reduced operating voltage and high emission efficiency. <Schätzung des SOMO- oder HOMO-Niveaus bei der Wechselwirkung zwischen dem Metall und der organischen Verbindung durch die quantenchemische Berechnung>

[0138] Next, the stabilization energy in the interaction between a metal, the first organic compound having a π-electron-deficient heteroaromatic ring with an electron-donor group, and the second organic compound having a π-electron-deficient heteroaromatic ring, as well as the SOMO or HOMO level formed in the interaction, were estimated by a quantum chemical calculation.

[0139] Gaussian 09 was used as the quantum chemical calculation program. The calculations were performed using the SGI 8600, manufactured by Hewlett Packard Enterprise. First, the most stable structures of the first organic compound in a ground state, the second organic compound in a ground state, the metal in a ground state, the composite material of the first organic compound and the metal in a ground state, the composite material of the second organic compound and the metal in a ground state, and the composite material of the first organic compound, the second organic compound, and the metal in a ground state were calculated using density functional theory (DFT). 6-311G(d,p) and LanL2DZ were used as the basis functions, and B3LYP was used as the functional.Next, the stabilization energy was calculated by subtracting the sum of the total energy of the organic compound(s) alone and the total energy of the metal alone from the total energy of the composite material composed of the organic compound(s) and the metal. That is, (stabilization energy) = (the total energy of the composite material composed of the organic compound(s) and the metal) - (the total energy of the organic compound(s) alone) - (the total energy of the metal alone).

[0140] The following tables show the results of the calculation using 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviation: Pyrrd-Phen) as the first organic compound, 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 8-(p-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzo[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm), 2-[3-(2,6-Dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) and 2-[4-(2-naphthalenyl)phenyl]-4-phenyl-6-spiro[9H-fluoren-9,9'-[9H]xanthen]-4-yl-1,3,5-triazine (abbreviation: βNP-SFx(4)Tzn) were used as the second organic compounds and indium (In) as the metal. Note that the HOMO and SOMO energy levels in the tables are calculated values ​​and may differ from the measured values. [Table 2] HOMO-Niveau (eV) Pyrrd-Phen -5,65 NBPhen -5,74 9mDBtBPNfpr -5,96 8mpTP4mDBtPBfpm -5,94 mPn-mDMePyPTzn -5,96 βNP-SFx(4)Tzn -5,93 [Table 3] Stabilisierungsenergie (eV) SOMO-Niveau (eV) NBPhen + In -1,5 -3,28 9mDBtBPNfpr + In -0,8 -3,64 8mpTP4mDBtPBfpm + In -0,8 -3,69 mPn-mDMePyPTzn + In -0,6 -3,08 βNP-SFx(4)Tzn + In -0,7 -3,51 [Table 4] Stabilisierungsenergie (eV) SOMO-Niveau (eV) Pyrrd-Phen + NBPhen + In -1,3 -3,02 Pyrrd-Phen + 9mDBtBPNfpr + In -1,9 -2,78 Pyrrd-Phen + 8mpTP4mDBtPBfpm + In -1,9 -2,86 Pyrrd-Phen + mPn-mDMePyPTzn + In -1,9 -2,99 Pyrrd-Phen + βNP-SFx(4)Tzn + In -1,8 -2,86

[0141] The tables show that the stabilization energy of the composite material composed of two materials, the metal (In) and the second organic compound (NBPhen, 9mDBtBPNfpr, 8mpTP-4mDBtPBfpm, mPn-mDMePyPTzn, or βNP-SFx(4)Tzn), has a negative value; therefore, when the organic compound and the metal are mixed, the state in which the organic compound and the metal interact is energetically more stable than the state in which the organic compound and the metal do not interact. In addition, the SOMO levels formed during the interaction are higher than the HOMO level of the first organic compound (Pyrrd-Phen) and the HOMO level of the second organic compound (NBPhen, 9mDBtBPNfpr, 8mpTP-4mDBtPBfpm, mPn-mDMePyPTzn or βNP-SFx(4)Tzn).

[0142] It should be noted that the composite material of the metal (In) and the second organic compound (NBPhen) with a π-electron-deficient heteroaromatic ring, which is the same as the 1,10-phenanthroline ring of the first organic compound (pyrr-phen), has a larger absolute value of the stabilization energy and is thus more stable than the composite material of the metal (In) and the second organic compound (9mDBtBPNfpr, 8mpTP-4mDBtPBfpm, mPn-mDMePyPTzn, or βNP-SFx(4)Tzn) with a π-electron-deficient heteroaromatic ring, which is different from the 1,10-phenanthroline ring. Therefore, the SOMO level formed here is also high.

[0143] In contrast, the composite material composed of three materials, the metal (In), the first organic compound (Pyrrd-Phen), and the second organic compound (9mDBtBPNfpr, 8mpTP-4mDBtPBfpm, mPn-mDMePyPTzn, or βNP-SFx(4)Tzn), which is an embodiment of the present invention, has a larger absolute value of the stabilization energy and is therefore more stable than the composite material composed of the two materials, the metal (In) and the second organic compound (9mDBtBPNfpr, 8mpTP-4mDBtPBfpm, mPn-mDMePyPTzn, or βNP-SFx(4)Tzn). The SOMO level formed here is higher than the HOMO level of the first organic compound (pyrr-phen) and the HOMO level of the second organic compound (9mDBtBPNfpr, 8mpTP-4mDBtPBfpm, mPn-mDMePyPTzn, or βNP-SFx(4)Tzn). The SOMO level is preferably high to achieve high electron injection properties.

[0144] Furthermore, the composite material composed of the metal (In), the first organic compound (pyrrd-phen), and the second organic compound (9mDBtBPNfpr, 8mpTP-4mDBtPBfpm, mPn-mDMePyPTzn, or βNP-SFx(4)Tzn) with a π-electron-deficient heteroaromatic ring different from the 1,10-phenanthroline ring of the first organic compound (pyrrd-phen). It has a larger absolute value of stabilization energy and is therefore more stable than the composite material composed of the metal (In), the first organic compound (pyrrd-phen), and the second organic compound (NBPhen) with a π-electron-deficient heteroaromatic ring identical to the 1,10-phenanthroline ring of the first organic compound (pyrrd-phen). Therefore, the SOMO level formed here is further higher.

[0145] As described above, when the organic compound (the first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donating group, the organic compound (the second organic compound) having the second π-electron-deficient heteroaromatic ring, and the metal interact with each other to form a composite material, the first π-electron-deficient heteroaromatic ring is preferably different from the second π-electron-deficient heteroaromatic ring for higher stability and higher electron-injection property.

[0146] As shown in the above tables, the composite material of the metal, the first organic compound, and the second organic compound is preferred because it has a large absolute value of stabilization energy and is thus stabilized. The SOMO level formed here is higher than the HOMO level of the first organic compound and the HOMO level of the second organic compound. The SOMO level is preferably high to achieve a high electron injection property. A high SOMO level is formed even when a metal that is stable in air, such as silver or indium, is used instead of an alkali metal compound or the like, and therefore an interlayer with high stability and high electron injection property can be formed. <zweite organische Verbindung>

[0147] The first region of the intermediate layer contains, in addition to the metal or metal oxide and the first organic compound, the second organic compound having a π-electron-deficient heteroaromatic ring. The second organic compound can improve heat resistance, electron transport properties, and the like. In one embodiment of the present invention, when the π-electron-deficient heteroaromatic ring contained in the first organic compound is referred to as a first π-electron-deficient heteroaromatic ring and the π-electron-deficient heteroaromatic ring contained in the second organic compound is referred to as a second π-electron-deficient heteroaromatic ring, the first π-electron-deficient heteroaromatic ring and the second π-electron-deficient heteroaromatic ring are preferably different rings.

[0148] As the second π-electron-deficient heteroaromatic ring, a heteroaromatic ring having an azole skeleton (an imidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring, a triazole ring, an oxadiazole ring, or a thiadiazole ring), a heteroaromatic ring having a pyridine skeleton, a heteroaromatic ring having a diazine skeleton, a heteroaromatic ring having a triazine skeleton, or the like is preferred, and a diazine ring (a pyrazine ring, a pyrimidine ring, or a pyridazine ring) or a triazine ring is particularly preferred because it is electrochemically stable and has a high electron-transport property.

[0149] It should be noted that the second π-electron-deficient heteroaromatic ring may have a fused structure.

[0150] In one embodiment of the present invention, the LUMO level of the second organic compound is lower than that of the first organic compound preferably by more than or equal to 0.20 eV and less than or equal to 0.50 eV, more preferably by more than or equal to 0.25 eV and less than or equal to 0.50 eV, even more preferably by more than or equal to 0.30 eV and less than or equal to 0.50 eV, even more preferably by more than or equal to 0.35 eV and less than or equal to 0.50 eV, even more preferably by more than or equal to 0.40 eV and less than or equal to 0.50 eV.

[0151] This means that if the LUMO level of the first organic compound is “LUMO1 (eV)” and the LUMO level of the second organic compound is “LUMO2 (eV)”, the LUMO2 preferentially satisfies the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.20

[0152] Preferably, the LUMO2 fulfills the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.25

[0153] Preferably, the LUMO2 fulfills the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.30

[0154] Preferably, the LUMO2 fulfills the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.35

[0155] Preferably, the LUMO2 fulfills the following formula: LUMO1−0.50≤LUMO2≤LUMO1−0.40

[0156] When the LUMO2 is within any of the above ranges, the light-emitting device of one embodiment of the present invention can be a tandem light-emitting device that has advantageous characteristics and a low operating voltage regardless of whether a photolithography process involving exposure of an EL layer to air is performed. Furthermore, the tandem light-emitting device can have high reliability.

[0157] An organic compound having electron transport properties can be used as the second organic compound. The organic compound having electron transport properties is preferably a substance with an electron mobility of greater than or equal to 1 × 10 -7 cm 2 / Vs, preferably higher than or equal to 1 × 10 -6 cm 2 / Vs in the case where the square root of the electric field strength [V / cm] is 600. It should be noted that any other substance can be used as long as the substance has an electron transport property higher than a hole transport property.

[0158] Specific examples of the organic compound with an electron transport property include the following compounds: organic compounds with an azole skeleton, such as: B. 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2"-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), 2-{4-[9,10-Di(2-naphthyl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviation: ZADN) and 4,7-Diphenyl-2,9-bis[4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl]-1,10-phenanthroline (abbreviation: DBimBphen); organic compounds with a diazine skeleton,such as 2-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-Carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-Phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 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), 6-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[3'-(Dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-Bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-Bis[3-(4-dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-Bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[Pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(Biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-Bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-Bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(Dibenzothiophen-4-yl)(1,1'-biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-Binaphthalene)-6-yl)]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(Pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (Abbreviation: 2,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (Abbreviation: 2,6(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (Abbreviation: 6mBP-4Cz2PPm), 2,6-Bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-Bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), 8-(p-Terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzo[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm) and 11-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 11mDBtBPPnfpr); and organic compounds with a triazine skeleton, such as. B. 2-(Biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(Benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(Benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazin (Abkürzung: PCCzPTzn), 9-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazol (Abkürzung: mPCCzPTzn-02), 2-[3'-(9,9-Dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazin (Abkürzung: mFBPTzn), 5-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazol (Abkürzung: mlNc(II)PTzn), 2-{3-[3-(Dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1 ,3,5-triazin (Abkürzung: mDBtBPTzn), 2,4,6-Tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazin (Abkürzung: TmPPPyTz), 2-[3-(2,6-Dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazin (Abkürzung: mPn-mDMePyPTzn), 11-[4-(Biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazol (Abkürzung: BP-Icz(II)Tzn), 2-[3'-(Triphenylen-2-yl)-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazin (Abkürzung: mTpBPTzn), 3-[9-(4,6-Diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazol (Abkürzung: PCDBfTzn), 2-(Biphenyl-3-yl)-4-phenyl-6-{8-[(1, 1':4',1"-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 2-[4-(2-naphthalenyl)phenyl]-4-phenyl-6-spiro[9H-fluoren-9,9'-[9H]xanthen]-4-yl-1,3,5-triazine (abbreviation: βNP-SFx(4)Tzn) and 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviation: mSiTrz).

[0159] Among the above, ZADN, mSiTrz, mPn-mDMePyPTzn, 8mpTP-4mDBtPBfpm, 11mDBtBPPnfpr, and βNP-SFx(4)Tzn are preferred as the second organic compound due to their suitable LUMO levels; therefore, the use of the organic compounds facilitates obtaining a tandem light-emitting device exhibiting favorable properties and a suppressed increase in operating voltage, even when fabricated by a process involving exposure of an EL layer to air.

[0160] The second organic compound preferably has 25 to 100 carbon atoms. When the second organic compound has 25 to 100 carbon atoms, it can exhibit excellent sublimability, thus preventing thermal decomposition of the organic compound during vacuum evaporation, and increasing the utilization efficiency of the material.

[0161] An organic compound with a glass transition temperature Tg higher than or equal to 100°C is preferably used as the second organic compound. Consequently, the interlayer exhibits high heat resistance and is not easily crystallized. Therefore, the interlayer is not easily crystallized even if part of the organic compound layer is processed by a lithography technique.

[0162] As a second organic compound, an organic compound with an acid constant pK sof less than 4. In this case, the second organic compound may have low water solubility and can therefore be very resistant to water and chemical solutions used during the process with a lithography technique.

[0163] An organic compound with an acid constant pK s of less than 4 has a lower water solubility than an organic compound with an acid constant pK s greater than or equal to 4. The water resistance of an interlayer containing an organic compound with an acid constant pK s of less than 4 as a second organic compound, can be higher than that of an intermediate layer containing an organic compound with an acid constant pK sof greater than or equal to 4 as the second organic compound. Furthermore, the occurrence of a problem such as detachment of the interlayer from another layer during the manufacturing process can be prevented. Consequently, the occurrence of a problem causing a defect in a light-emitting device can be prevented.

[0164] As the second organic compound, for example, 8BP-4mDBtPBfpm, 4,8mDBtP2Bfpm, 6BP-4Cz2PPm, 2mDBTBPDBq-II, 9mDBtBPNfpr, 11mDBtBPPnfpr, mPCCzPTzn-02, BP-BPlcz(II)Tzn or the like can be used.

[0165] It should be noted that the acid constant pK s of 4.8mDBtP2Bfpm is 0.60. The acid constant pK s of 11mDBtBPPnfpr is -1.85. In the case where the acid constant pK s of an organic compound is unknown, the acid constants pK s of the frameworks in the organic compound, and the largest acid constant pKs can be used as acid constant pK s the organic compound.

[0166] An organic compound with a polarization term δ p less than or equal to 4.0 MPa 0,5 in a solubility parameter δ can be used as a second organic compound. An organic compound with a polarization term δ p less than or equal to 4.0 MPa 0,5 in a solubility parameter δ, for example, has a lower water solubility than an organic compound with a polarization term δ p greater than 4.0 MPa 0,5 in a solubility parameter δ. The water resistance of the intermediate layer containing an organic compound with a polarization term δ p less than or equal to 4.0 MPa 0,5as a second organic compound, can be higher than that of the intermediate layer, which contains an organic compound with a polarization term δ p greater than 4.0 MPa 0,5 as a second organic compound. Furthermore, the occurrence of a problem such as detachment of the intermediate layer from another layer in the photolithography process can be prevented. Consequently, the occurrence of a problem that causes a defect in a light-emitting device can be prevented.

[0167] Japanese Patent Laid-Open No. 2017-173056 describes that the polarization term δ p the solubility parameter δ of water 16.0 MPa 0,5 amounts.

[0168] An organic compound that has a larger difference in the polarization term δ pof the solubility parameter δ from that of water, which serves as a solvent, is preferred because it has a lower water solubility. Therefore, an organic compound with a polarization term δ p less than or equal to 4.0 MPa 0,5 in the solubility parameter δ preferably used as a second organic compound.

[0169] As a second organic compound, for example, 8BP-4mDBtPBfpm, 4,8mDBtP2Bfpm, 6BP-4Cz2PPm, 2mDBTBPDBq-II, 9mDBtBPNfpr, 11mDBtBPPnfpr, mPCCzPTzn-02 or BP-BPlcz(II)Tzn can be used.

[0170] It should be noted that the polarization term δ p of the solubility parameter δ 3.5 MPa 0,5 in 8BP-4mDBtPBfpm, 3.4 MPa 0,5 in 4.8mDBtP2Bfpm, 3.4 MPa 0,5 in 6BP-4Cz2PPm, 3.2 MPa 0,5 in 2mDBTBPDBq-II, 3.8 MPa 0,5 in 9mDBtBPNfpr, 3.1 MPa 0,5 in 11mDBtBPPnfpr, 3.5 MPa 0,5 in mPCCzPTzn-02 and 3.2 MPa 0,5in BP-BPlcz(II)Tzn.

[0171] The polarization term δ p of the solubility parameter δ is calculated by the following calculation procedure.

[0172] Desmond, manufactured by Schrödinger, Inc., is used as the software for classical molecular dynamics calculations. The OPLS-2005 force field is also used. The calculations are performed using Apollo 6500, manufactured by Hewlett Packard Enterprise Development.

[0173] A standard cell containing approximately 32 molecules is used as the computational model. As the initial molecular structure of each compound, the most stable structures (singlet ground states) determined by ab initio calculations and structures with energies close to those of the most stable structures are mixed in equal proportions and randomly arranged so that molecules do not collide. Then, using Monte Carlo simulated annealing and the OPLS-2005 force field, the structures are randomly moved and rotated to move the molecules. Furthermore, the molecules are moved toward the center of the standard cell in such a way as to maximize density, thus obtaining the initial arrangement.

[0174] Jaguar, the quantum chemical computing software, is used for the ab initio calculation, and the most stable structure in the singlet ground state is calculated using density functional theory (DFT). 6-31G** is used as the basis function, and B3LYP-D3 is used as the functional. The structure subjected to the quantum chemical calculation is sampled by conformational analysis in mixed torsional / low-mode sampling using the Maestro GUI, manufactured by Schrödinger, Inc. The calculation is performed using Apollo 6500, manufactured by Hewlett Packard Enterprise Development.

[0175] The initial assembly described above is subjected to Brownian motion simulation and then defined in NVT ensemble. Subsequently, the calculation is performed in NPT ensemble for a sufficient relaxation time (30 ns) under conditions of 1 atm and 300 K with respect to time steps in which molecular vibration is reproduced (2 fs), thus resulting in an amorphous solid. The solubility parameter δ of the resulting amorphous solid is defined by the following formula. δ=(ΔHv−RTVm)1 / 2

[0176] Here, ΔHv represents a heat of vaporization obtained by subtracting the total energy of individual molecules averaged in the whole molecular dynamics calculation from the energy of the standard cell, Vm represents the molar volume, R represents the gas constant, and T represents the temperature. There is a tendency for the solubility to decrease as the difference in the solubility parameter δ between a substance serving as a solvent and a substance serving as a solute becomes larger.

[0177] The solubility parameter δ can be converted into a diffusion term δ d and a polarization term δ p The van der Waals interaction contributes to the diffusion term δ d and the electrostatic interaction contributes to the polarization term δ pIn particular, the electrostatic interaction between a solute and the dipoles of a water molecule contributes significantly to the water solubility of the solute. The water solubility of an organic compound, which can be used as a second organic compound, actually correlates well with the calculated polarization term δ p the solubility parameter δ.

[0178] It should be noted that the LUMO level of the second organic compound is preferably lower than that of the first organic compound. In this case, electrons can be easily donated from the donor level formed by the first organic compound and the metal or metal oxide to the second organic compound. The LUMO level of the second organic compound is preferably lower than that of the first organic compound, also because the second organic compound preferably has an electron-transport property.

[0179] The LUMO level of the second organic compound is preferably higher than or equal to -3.0 eV and lower than or equal to -2.0 eV, more preferably higher than or equal to -3.0 eV and lower than or equal to -2.5 eV. The LUMO level of the first organic compound is preferably higher than or equal to -3.0 eV and lower than or equal to -2.0 eV, more preferably higher than or equal to -2.7 eV and lower than or equal to -2.0 eV.

[0180] In the above case, electrons can be easily donated from the donor level formed by the first organic compound and the metal or metal oxide to the second organic compound. Furthermore, electrons can be easily transported within the second organic compound.

[0181] The first region preferably contains the second organic compound in addition to the metal or metal oxide and the first organic compound, in which case an efficient interaction between the materials occurs. This can be confirmed by measuring the spin density using electron spin resonance (ESR).

[0182] For example, the spin density measured by ESR of a film containing the metal or metal oxide and the first organic compound is preferably higher than that of a film containing the metal or metal oxide and the second organic compound. The spin density measured by ESR of a film containing the metal or metal oxide, the first organic compound, and the second organic compound is preferably higher than that of a film containing only two of the metal or metal oxide, the first organic compound, and the second organic compound. In this case, it is determined that an interaction between the materials occurs efficiently.

[0183] In particular, in the film containing the metal or metal oxide and the first organic compound, the density of spins attributable to a signal observed at a g-factor of approximately 2.00 is measured by an electron spin resonance method to be, for example, higher than or equal to 5 × 10 16 Spins / cm 3 , preferably higher than or equal to 1 × 10 17 Spins / cm 3In such a case, it can be confirmed that the interaction between the materials occurs efficiently in the film containing the metal or metal oxide and the first organic compound in combination. Alternatively, in the film containing the metal or metal oxide, the first organic compound, and the second organic compound, the density of spins attributable to a signal observed at a g-factor of approximately 2.00 is measured by an electron spin resonance method to be, for example, higher than or equal to 5 × 10 16 Spins / cm 3 , preferably higher than or equal to 1 × 10 17 Spins / cm 3In such a case, it can be confirmed that the interaction between the materials occurs more efficiently in the film containing the metal or metal oxide, the first organic compound, and the second organic compound in combination than in the film containing only two of the metal or metal oxide, the first organic compound, and the second organic compound. The density of spins attributable to a signal observed at a g-factor of approximately 2.00 is measured by an electron spin resonance method to be, for example, less than or equal to 2 × 10 16 Spins / cm 3in a mixed film containing the metal or metal oxide and the second organic compound. The density of spins attributable to a signal observed at a g-factor of approximately 2.00 is measured by an electron spin resonance method to be, for example, less than or equal to 2 × 10 16 Spins / cm 3 to be in a mixed film containing the first organic compound and the second organic compound.

[0184] In the first range, the molar ratio of the metal or the metal oxide to the first organic compound (or the sum of the first organic compound and the second organic compound) is preferably greater than or equal to 0.1 and less than or equal to 10, more preferably greater than or equal to 0.2 and less than or equal to 5, even more preferably greater than or equal to 0.5 and less than or equal to 2. Alternatively, the volume ratio of the metal or the metal oxide to the first organic compound (or the sum of the first organic compound and the second organic compound) is preferably greater than or equal to 0.01 and less than or equal to 0.3, more preferably greater than or equal to 0.02 and less than or equal to 0.2, even more preferably greater than or equal to 0.05 and less than or equal to 0.1.When the metal or metal oxide and the first organic compound (or the first organic compound and the second organic compound) are mixed in such a ratio, the intermediate layer having favorable electron-injection property can be provided. Although the second organic compound is not necessarily used, the volume ratio of the first organic compound to the second organic compound is preferably greater than or equal to 0.1 and less than or equal to 10, more preferably greater than or equal to 0.2 and less than or equal to 5, even more preferably greater than or equal to 0.5 and less than or equal to 2. When the first organic compound and the second organic compound are mixed in such a ratio, the intermediate layer having favorable electron-transport property can be provided.When an organic compound with favorable thermophysical properties with high Tg is used as the second organic compound, a highly reliable light-emitting device can be provided.

[0185] The thickness of the first region is preferably greater than or equal to 2 nm and less than or equal to 20 nm, more preferably greater than or equal to 5 nm and less than or equal to 10 nm. In the case where the first region has a multi-layer structure consisting of a layer of the metal or the metal oxide and a layer containing the first organic compound, the thickness of the layer of the metal or the metal oxide is preferably greater than or equal to 0.1 nm and less than or equal to 5 nm, more preferably greater than or equal to 0.2 nm and less than or equal to 2 nm. In the case where the first region has a multi-layer structure consisting of a layer of the metal or the metal oxide and a layer containing the first organic compound, the thickness of the layer containing the first organic compound is preferably greater than or equal to 2 nm and less than or equal to 20 nm, more preferably greater than or equal to 5 nm and less than or equal to 10 nm. < <zweiter Bereich»

[0186] The second region is a P-type CGL and is preferably formed using a composite material containing an organic compound having a hole-transporting property (a third organic compound) and a substance having an electron-accepting property with respect to the organic compound having a hole-transporting property.

[0187] As the substance having an electron accepting property with respect to the organic compound having a hole transporting property, an organic compound having an electron withdrawing group (e.g., a halogen group or a cyano group) can be used, and it is more preferable to use an organic compound having a halogen group and / or a cyano group. Specific examples include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. A compound in which electron-withdrawing groups are bonded to a fused aromatic ring containing a plurality of heteroatoms, such as HAT-CN, is particularly preferred because of its thermal stability.A [3]radialene derivative having an electron-withdrawing group (particularly a cyano group, a halogen group such as a fluorine group, or the like) exhibits a very high electron-accepting property and is thus preferred. Specific examples include 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], and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0188] As a substance having an electron-accepting property, in addition to the above-described organic compounds, a transition metal or an oxide thereof, such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, or manganese oxide, can be used. In this case, one embodiment of the present invention can be considered a light-emitting device in which a P-type CGL and an N-type CGL contain different metals or metal oxides in an intermediate layer. Alternatively, the light-emitting device can be considered a light-emitting device in which a P-type CGL and an N-type CGL contain different metals or metal oxides and organic compounds.When the metal or metal oxide that is stable is used for both the P-type CGL and the N-type CGL, a tandem light-emitting device can be fabricated with an interlayer that is stable to oxygen and water in the air as well as water and a chemical solution used during the fabrication process.

[0189] As the organic compound having a hole-transporting property used in the composite material, any of various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and high-molecular compounds (e.g., oligomers, dendrimers, and polymers) can be used. Note that the organic compound having a hole-transporting property used in the composite material preferably has a hole mobility of greater than or equal to 1 × 10 -6 cm 2 / Vs. The organic compound having a hole-transporting property used in the composite material is preferably a compound having a condensed aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the condensed aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferred. As the π-electron-rich heteroaromatic ring, a condensed aromatic ring having at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferred; in particular, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to the carbazole ring or the dibenzothiophene ring is preferred.

[0190] Such an organic compound having a hole-transport property more preferably has any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. Specifically, an aromatic amine having a substituent including a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group can be used. Note that the organic compound having a hole-transport property preferably has an N,N-bis(4-biphenyl)amino group to enable the fabrication of a light-emitting device with a long lifetime.

[0191] Specific examples of the organic compound with a hole transport property include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: 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 (Abbreviation: BBAßNB), 4-[4-(2-Naphthyl)phenyl]-4',4''-diphenyltriphenylamine (Abbreviation: BBAßNBi), 4,4'-Diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (Abbreviation: BBAαNβNB), 4,4'-Diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-Diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPßNB-03), 4,4'-Diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(ßN2)B), 4,4'-Diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(ßN2)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: TPBiAßNB), 4-(3-Biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAßNBi), 4-(4-Biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: TPBiAßNBi), 4-Phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4'-Bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP),4'-[4-(3-Phenyl-9H-carbazol-9-yl)phenyl]tris(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(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-Bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-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'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi),4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-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 and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine.

[0192] Examples of the aromatic amine compounds that can be used as a material with a hole-transport property include N,N'-di(ρ-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD) and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0193] The material having an electron-accepting property in the P-type CGL preferably has an electron-accepting property. The material having an electron-accepting property preferably has an electron-accepting property relative to an organic compound having a hole-transporting property. When the material having an electron-accepting property has an electron-accepting property, the P-type CGL can serve as a charge-generating layer due to charge separation in the P-type CGL and can therefore serve as an intermediate layer of a tandem light-emitting device. Furthermore, it is preferable that a signal be observed by electron spin resonance spectroscopy in the P-type CGL. For example, the density of spins attributable to a signal observed at a g-factor of approximately 2.00 is preferably greater than or equal to 1 × 10 17 Spins / cm 3 , preferably higher than or equal to 1 × 10 18Spins / cm 3 , more preferably higher than or equal to 1 × 10 19 Spins / cm 3 . < <dritter Bereich»

[0194] The third region may be provided between the first region and the second region in the intermediate layer.

[0195] The third region contains a substance having an electron transport property and has functions such as smoothly transmitting and receiving electrons between the first region and the second region to reduce the operating voltage and reducing the interaction between the first region and the second region to improve reliability.

[0196] The LUMO level of the substance having an electron transport property contained in the third region is preferably located between the LUMO level of the acceptor substance in the second region and the LUMO level of the organic compound in a layer contained in the light-emitting unit on the anode side and in contact with the intermediate layer.

[0197] A specific energy level of the LUMO level of the substance having an electron-transport property used in the third region is preferably higher than or equal to -5.0 eV, more preferably higher than or equal to -5.0 eV and lower than or equal to -3.0 eV, even more preferably higher than or equal to -4.30 eV and lower than or equal to -3.00 eV, even more preferably higher than or equal to -4.30 eV and lower than or equal to -3.30 eV, in which case, an increase in the operating voltage can be suppressed. Note that, as the substance having an electron-transport property used in the third region, a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand is preferably used.

[0198] Specific examples of the substance having an electron transport property used in the third field include a perylenetetracarboxylic acid derivative such as diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA), 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA-F6), 3,4,9,10-perylenetetracarboxylic acid diimide (abbreviation: PTCDI) or 3,4,9,10-perylenetetracarboxylic bis-benzimidazole (abbreviation: PTCBI), (C 60 -I h )[5,6]Fullerene (abbreviation: C 60 ) and (C 70 -D 5h )[5,6]Fullerene (abbreviation: C 70). It is also possible to use a compound having a heterophane skeleton, which is a cyclophane skeleton with a hetero ring; for example, a phthalocyanine compound such as phthalocyanine (abbreviation: H2Pc) can be used as the compound. Alternatively, a metal phthalocyanine containing copper, zinc, cobalt, iron, chromium, nickel, or the like, or a derivative thereof, such as copper phthalocyanine (abbreviation: CuPc), zinc phthalocyanine (abbreviation: ZnPc), cobalt phthalocyanine (abbreviation: CoPc), iron phthalocyanine (abbreviation: FePc), tin phthalocyanine (abbreviation: SnPc), tin oxide phthalocyanine (abbreviation: SnOPc), titanium oxide phthalocyanine (abbreviation: TiOPc), or vanadium oxide phthalocyanine (abbreviation: VOPc) can be used. In particular, a phthalocyanine-based metal complex such as copper phthalocyanine or zinc phthalocyanine, or 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine is preferably used.

[0199] The thickness of the third region is preferably greater than or equal to 1 nm and less than or equal to 10 nm, more preferably greater than or equal to 2 nm and less than or equal to 5 nm.

[0200] The light-emitting device of one embodiment of the present invention having the above-mentioned structure can have advantageous characteristics even if exposure to air or a photolithography process including exposure to air is performed before the second electrode is formed. (Embodiment 2)

[0201] In this embodiment, light-emitting devices of one embodiment of the present invention will be described in detail.

[0202] Fig. 1 is a schematic diagram of a light-emitting device 130 of an embodiment of the present invention. The light-emitting device 130 includes a first electrode 101 over an insulator 100 and an organic compound layer 103 between the first electrode 101 and a second electrode 102. As described in Embodiment 1, the organic compound layer 103 includes a plurality of light-emitting units (a first light-emitting unit 501 and a second light-emitting unit 502 in Fig. 1) and an intermediate layer 116.

[0203] The first light-emitting unit 501 includes at least a first light-emitting layer 113_1, and the second light-emitting unit 502 includes at least a second light-emitting layer 113_2. The first light-emitting layer 113_1 and the second light-emitting layer 113_2 are each a layer containing a light-emitting substance and emit light when a voltage is applied between the first electrode 101 and the second electrode 102.

[0204] The first light-emitting unit 501 preferably comprises, in addition to the layers described above, functional layers such as a hole injection layer 111, a first hole transport layer 112_1 and a first electron transport layer 114_1, as in Fig. 1. The first light-emitting unit 501 may include functional layers other than the functional layers described above, such as an electron-blocking layer and an exciton-blocking layer. Alternatively, any of the above-described layers may be omitted.

[0205] The second light-emitting unit 502 preferably comprises, in addition to the layers described above, functional layers such as a second hole transport layer 112_2, a second electron transport layer 114_2 and an electron injection layer 115, as in Fig. 1. The second light-emitting unit 502 may include functional layers other than the functional layers described above, such as a hole-blocking layer, an electron-blocking layer, and an exciton-blocking layer. Alternatively, any of the above-described layers may be omitted.

[0206] Furthermore, the intermediate layer 116 comprises at least a first region 119, a third region 118 and a second region 117 from the side of the anode (the first electrode 101 in Fig. 1). The first region 119 contains, as described in Embodiment 1, a metal or a metal oxide, an organic compound (the first organic compound) having the first π-electron-deficient heteroaromatic ring with an electron-donating group, and an organic compound (the second organic compound) having the second π-electron-deficient heteroaromatic ring. The second region 117 generates charge carriers by applying a voltage. The second region 117 preferably contains an organic compound having a hole-transporting property and a substance having an electron-accepting property with respect to the organic compound. The third region 118 has an electron-transporting property and is formed using a material having a specific LUMO level.The light-emitting device comprising the third region may have a reduced operating voltage, a suppressed reduction in reliability, and an improved emission efficiency.

[0207] Since the structures of the first region 119, the second region 117, and the third region 118 have been concretely described in detail in Embodiment 1, their repeated descriptions are omitted.

[0208] It is preferable that, in this embodiment, the first electrode 101 comprises an anode, and the second electrode 102 comprises a cathode. The first electrode 101 and the second electrode 102 may each have a single-layer structure or a multi-layer structure. In the case of the multi-layer structure, a layer in contact with the organic compound layer 103 serves as an anode or a cathode. In the case where the electrodes each have a multi-layer structure, there is no limitation on the work functions of materials for layers other than the layer in contact with the organic compound layer 103, and the materials can be selected according to required properties such as resistance, ease of processing, reflectance, light transmittance, and stability.

[0209] The anode is preferably formed using any of metals, alloys, and conductive compounds with high work functions (particularly higher than or equal to 4.0 eV), mixtures thereof, and the like. Specific examples include indium oxide-tin oxide (ITO), indium oxide-tin oxide containing silicon or silicon oxide (ITSO), indium oxide-zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). Films of such conductive metals or oxides thereof are usually formed by a sputtering method, but they can be formed using a sol-gel method or the like. For example, an indium oxide-zinc oxide film is formed by a sputtering method using a target in which 1 wt% to 20 wt% of zinc oxide is added to indium oxide.Furthermore, an indium oxide film containing tungsten oxide and zinc oxide (IWZO) can be formed by a sputtering method using a target in which 0.5 wt% to 5 wt% of tungsten oxide and 0.1 wt% to 1 wt% of zinc oxide are added to indium oxide. Alternatively, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), titanium (Ti), aluminum (Al), a nitride of a metal material (e.g., titanium nitride), or the like can be used for the anode. The anode can be a layered arrangement of any of these materials. For example, a film in which Al, Ti, and ITSO are stacked on top of Ti in this order is preferred because the film has high efficiency thanks to high reflectivity and enables high resolution of several thousand ppi. Graphene can also be used for the anode.When a composite material, which may be included in the hole injection layer 111 described below, is used for a layer (typically the hole injection layer) in contact with the anode, an electrode material may be selected regardless of its work function.

[0210] The hole injection layer 111 is provided in contact with the anode and has a function of facilitating the injection of holes into the organic compound layer 103. The hole injection layer 111 can be formed using phthalocyanine (abbreviation: H2Pc), a phthalocyanine-based compound or complex compound such as copper phthalocyanine (abbreviation: CuPc), an aromatic amine compound such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or a high molecular compound such as phthalocyanine (abbreviation: DPAB). B. Poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS).

[0211] The hole-injection layer 111 can be formed using a substance having an electron-accepting property. Examples of the substance having an electron-accepting property include organic compounds having an electron-withdrawing group (a halogen group or a cyano group), such as cyano group. E.g., 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. A compound in which electron-withdrawing groups are bonded to a fused aromatic ring containing a plurality of heteroatoms, such as HAT-CN, is particularly preferred because of its thermal stability. A [3]radialene derivative containing an electron-withdrawing group (especially a cyano group, a halogen group, such asA compound having a fluorine group (e.g., a fluorine group, or the like) has a very high electron-accepting property and is thus preferred. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzene acetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzene acetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzene acetonitrile]. As a substance having an electron-accepting property, in addition to the organic compounds described above, a transition metal oxide such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, or manganese oxide can be used.

[0212] The hole injection layer 111 is preferably formed using a composite material containing any of the above-described materials having an electron accepting property and an organic compound having a hole transporting property.

[0213] As the organic compound having a hole-transporting property used in the composite material, any of various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and high-molecular compounds (e.g., oligomers, dendrimers, and polymers) can be used. Note that the organic compound having a hole-transporting property used in the composite material preferably has a hole mobility of greater than or equal to 1 × 10 -6 cm 2 / Vs. The organic compound having a hole-transporting property used in the composite material is preferably a compound having a condensed aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the condensed aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferred. As the π-electron-rich heteroaromatic ring, a condensed aromatic ring having at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton in the ring is preferred; in particular, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further condensed with a carbazole ring or a dibenzothiophene ring is preferred.

[0214] Such an organic compound having a hole-transport property more preferably has any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. Specifically, an aromatic amine having a substituent including a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group can be used. Note that the organic compound having a hole-transport property preferably has an N,N-bis(4-biphenyl)amino group to enable the fabrication of a light-emitting device with a long lifetime.

[0215] Specific examples of the organic compound with a hole transport property include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: 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 (Abbreviation: BBAßNB), 4-[4-(2-Naphthyl)phenyl]-4',4''-diphenyltriphenylamine (Abbreviation: BBAßNBi), 4,4'-Diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (Abbreviation: BBAαNβNB), 4,4'-Diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-Diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPßNB-03), 4,4'-Diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(ßN2)B), 4,4'-Diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(ßN2)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: TPBiAßNB), 4-(3-Biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAßNBi), 4-(4-Biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: TPBiAßNBi), 4-Phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4'-Bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP),4'-[4-(3-Phenyl-9H-carbazol-9-yl)phenyl]tris(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(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-Bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-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'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi),4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-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 and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine.

[0216] Examples of the aromatic amine compounds that can be used as a material with a hole-transport property include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD) and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0217] Forming the hole injection layer 111 can improve the hole injection property, resulting in the light-emitting device being able to operate at a low voltage.

[0218] Among substances having an electron acceptor property, the organic compound having an electron acceptor property is easily used because it is easily deposited by evaporation.

[0219] The hole-transport layer 112 is formed using an organic compound having a hole-transport property. The organic compound having a hole-transport property preferably has a hole mobility of greater than or equal to 1 × 10 -6 cm 2 / Vs on.

[0220] Examples of the material having a hole transport property include compounds with an aromatic amine skeleton, such as: B. 4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-Diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-Bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-Diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluorene-2-amine (abbreviation: PCBAF) and N-Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF); compounds with a carbazole skeleton, such as: B. 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), 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-Naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP), 9-(3-Biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-Biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-Di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-(2-Naphthyl)-9'-[1,1':4',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-Naphthyl)-9'-[1,1':3',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-Naphthyl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-Phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-Biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylen-2-yl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole and 9-[4-(9-phenyl-9H-carbazol-3-yl)-phenyl]phenanthrene (abbreviation: PCPPn); compounds with a thiophene skeleton, such as B. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV); and compounds with a furan skeleton, such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above materials, the compound with an aromatic amine skeleton and the compound with a carbazole skeleton are preferred because these compounds are highly reliable, have high hole-transport properties, and contribute to a reduction in operating voltage. Note that any of the substances given as examples of the material with a hole-transport property used in the composite material for the hole-injection layer 111 can also be suitably used as a material contained in the hole-transport layer 112.

[0221] The light-emitting layer 113 (the light-emitting layer 113_1 and the light-emitting layer 113_2) is a layer containing a light-emitting substance, and preferably contains a light-emitting substance and a host material. The light-emitting layer 113 may additionally contain other materials. Alternatively, the light-emitting layer 113 may be a layered arrangement of layers that differ only in the composition ratio.

[0222] Fluorescent substances, phosphorescent substances, substances that exhibit thermally activated delayed fluorescence (TADF), or other light-emitting substances can be used as the light-emitting substance.

[0223] Examples of materials that can be used as fluorescent substances in the light-emitting layer are as follows. Other fluorescent substances can also be used.

[0224] The examples include 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-Bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-Diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), Perylene, 2,5,8,11-Tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N'-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis(N,N',N-triphenyl-1,4-phenylenediamine) (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]chrysen-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-Bis(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(biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-Bis(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(biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT),2-(2-{2-[4-(Dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-Methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene propanedinitrile (abbreviation: DCM2), N,N,N',N'-Tetrakis(4-methylphenyl)tetracen-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[j]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: BisDCJTM), N,N-Diphenyl-N,N'-(1,6-pyrenediyl)bis[(6-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02) and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02). Condensed aromatic diamine compounds, typically pyrenediamine compounds, such as B. 1,6FLPAPrn, 1,6mMemFLPAPrn and 1,6BnfAPrn-03, are particularly preferred due to their high hole-trapping properties, high emission efficiency or high reliability.

[0225] A condensed heteroaromatic compound containing nitrogen and boron, especially a compound having a diaza-boranaphtho-anthracene skeleton, has a narrow emission spectrum, emits blue light with favorable color purity, and can therefore be suitably used. Examples of the compound include 5,9-diphenyl-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene (abbreviation: DABNA1), 9-(biphenyl-3-yl)-N,N,5,11-tetraphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-3-amine (abbreviation: DABNA2), 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: DPhA-tBu4DABNA), 2,12-Di(tert-butyl)-N,N,5,9-tetra(4-tert-butylphenyl)-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: tBuDPhA-tBu4DABNA), 2,12-Di(tert-butyl)-5,9-di(4-tert-butylphenyl)-7-methyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: Me-tBu4DABNA), N 7 ,N 7 ,N 13 ,N 13,5,9,11,15-Octaphenyl-5H,9H,11H,15H-[1,4]benzazaborino[2,3,4-kl][1,4]benzazaborino[4',3',2':4,5][1,4]benzazaborino[3,2-b]phenazaborine-7,13-diamine (abbreviation: v-DABNA) and 2-(4-tert-butylphenyl)benz[5,6]indolo[3,2,1-jk]benzo[b]carbazole (abbreviation: tBuPBibc).

[0226] In addition to the above compounds, 9,10,11-Tris[3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3',2',1':8,1][1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: BBCz-G), 9,11-Bis[3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3',2',1':8,1][1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: BBCz-Y) or similar can be used appropriately.

[0227] Examples of the material that can be used when a phosphorescent substance is used as a light-emitting substance in the light-emitting layer are as follows.

[0228] The examples include an organometallic iridium complex with a 4H-triazole framework, such as 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]) and tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]); an organometallic iridium complex with a 1H-triazole framework, such as. B. Tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3] and Tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]); an organometallic iridium complex with an imidazole framework, such as fac-Tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpim) 3] ), Tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]) and Tris(2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazol-2-yl-κN 3}-4-cyanophenyl-κC) (abbreviation: CNImlr); an organometallic complex with a benzimizazolidene framework, such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC 2 )phenyl-κC]iridium(III) (abbreviation: [Ir(cb)3]); and an organometallic iridium complex in which a phenylpyridine derivative with an electron-withdrawing group is a ligand, such as bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III)tetrakis(1-pyrazolyl)borate (abbreviation: Flr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III) picolinate (abbreviation: Flrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2 '}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]) and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III) acetylacetonate (abbreviation: Flr(acac)). These compounds emit blue phosphorescence light and exhibit an emission peak in the wavelength range of 450 nm to 520 nm.

[0229] Further examples include organometallic iridium complexes with a pyrimidine framework, such as: B. 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)]) and (Acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]); organometallic iridium complexes with a pyrazine framework, such as(Acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]); organometallic iridium complexes with a pyridine framework, such as tris(2-phenylpyridinato-N,C 2' )iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2' )iridium(III)acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2' )iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2')iridium(III)acetylacetonat (Abkürzung: [Ir(pq)2(acac)]), [2-d3-Methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridin-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (Abkürzung: [Ir(5mppy-d3)2(mbfpypy-d3)]), [2-d3-Methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridin-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (Abkürzung: [Ir(ppy)2(mbfpypy-d3)]), [2-(4-d3-Methyl-5-phenyl-2-pyridinyl-κN 2 )phenyl-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN 2)phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy-d3)2(mdppy-d3)]), [2-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mbfpypy)]) and [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mdppy)]); and a rare earth metal complex, such as B. Tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). These compounds emit predominantly green phosphorescence light and exhibit an emission peak in the wavelength range of 500 nm to 600 nm. It should be noted that organometallic iridium complexes with a pyrimidine framework exhibit significantly high reliability or emission efficiency and are therefore particularly preferred.

[0230] Further examples include organometallic iridium complexes with a pyrimidine framework, such as (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)]) and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]); organometallic iridium complexes with a pyrazine framework, such as B. (Acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]) and (Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]); organometallic iridium complexes with a pyridine framework, such as tris(1-phenylisoquinolinato-N,C 2' )iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2')iridium(III)acetylacetonate (abbreviation: [Ir(piq)2(acac)]), (3,7-diethyl-4,6-nonanedionato-κ0 4 , κ0 6 )bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC]iridium(III) and (3,7-diethyl-4,6-nonanedionato-κO 4 ,κO 6 )bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC]iridium(III); platinum complexes, such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviation: PtOEP); and rare earth metal complexes, such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]). These compounds emit red phosphorescence light and exhibit an emission peak in the wavelength range of 600 nm to 700 nm. Furthermore, the organometallic iridium complexes with a pyrazine framework can provide red light emission with favorable chromaticity.

[0231] In addition to the above phosphorescent compounds, known phosphorescent compounds can also be selected and used.

[0232] Examples of the TADF material include a fullerene, a derivative thereof, an acridine, a derivative thereof, and an eosin derivative. Further, a metal-containing porphyrin, such as a porphyrin containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), can be cited. Examples of the metal-containing porphyrin include a protoporphyrin-tin fluoride complex (SnF2(Proto IX)), a mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), a hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), a coproporphyrin-tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), an octaethylporphyrin-tin fluoride complex (SnF2(OEP)), an etioporphyrin-tin fluoride complex (SnF2(Etio I)) and an octaethylporphyrin-platinum chloride complex (PtCl2OEP), which are represented by the following structural formulas.

[0233] Alternatively, a heterocyclic compound having a π-electron-rich heteroaromatic ring and / or a π-electron-poor heteroaromatic ring and represented by the following structural formulas, such as: B. 2-(Biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn) (Abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS) or 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA).Such a heterocyclic compound is preferred because it exhibits high electron-transport and hole-transport properties due to a π-electron-rich heteroaromatic ring and a π-electron-poor heteroaromatic ring. Among frameworks containing the π-electron-poor heteroaromatic ring, a pyridine framework, a diazine framework (a pyrimidine framework, a pyrazine framework, and a pyridazine framework), and a triazine framework are preferred due to their high stability and reliability. In particular, a benzofuropyrimidine framework, a benzothienopyrimidine framework, a benzofuropyrazine framework, and a benzothienopyrazine framework are preferred due to their high electron-accepting properties and high reliability.Among the π-electron-rich heteroaromatic ring skeletons, an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton exhibit high stability and reliability; therefore, at least one of these skeletons is preferably included. As the furan skeleton, a dibenzofuran skeleton is preferred, and as the thiophene skeleton, a dibenzothiophene skeleton is preferred. As the pyrrole skeleton, indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferred.It should be noted that a substance in which the π-electron-rich heteroaromatic ring is directly bonded to the π-electron-poor heteroaromatic ring is particularly preferred because both the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-poor heteroaromatic ring are improved, the energy difference between the S1 level and the T1 level becomes small, and therefore thermally activated delayed fluorescence can be obtained with high efficiency. It should be noted that an aromatic ring to which an electron-withdrawing group, such as a cyano group, is bonded can be used instead of the π-electron-poor heteroaromatic ring. An aromatic amine skeleton, a phenazine skeleton, or the like can be used as the π-electron-rich skeleton.As the π-electron-deficient skeleton, a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring or a heteroaromatic ring having a cyano group or a nitrile group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, or the like can be used. As described above, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used instead of at least one of the π-electron-deficient heteroaromatic ring and the π-electron-rich heteroaromatic ring.

[0234] It should be noted that a TADF material is a material that has a small difference between the S1 level and the T1 level and has the function of converting triplet excitation energy into singlet excitation energy through reverse intersystem crossing. Thus, a TADF material can upconvert triplet excitation energy to singlet excitation energy (i.e., reverse intersystem crossing) using a small amount of thermal energy and efficiently generate a singlet excited state. In addition, the triplet excitation energy can be converted into light emission.

[0235] An exciplex whose excited state is formed by two types of substances has a very small difference between the S1 level and the T1 level and serves as a TADF material that can convert the triplet excitation energy into the singlet excitation energy.

[0236] A phosphorescence spectrum observed at a low temperature (e.g., 77 K to 10 K) is used for an index of the T1 level. When the energy level with a wavelength of the line obtained by extrapolating a tangent to the fluorescence spectrum at a tail on the short wavelength side is the S1 level, and the energy level with a wavelength of the line obtained by extrapolating a tangent to the phosphorescence spectrum at a tail on the short wavelength side is the T1 level, the difference between the S1 level and the T1 level of the TADF material is preferably less than or equal to 0.3 eV, more preferably less than or equal to 0.2 eV.

[0237] When a TADF material is used as the light-emitting substance, the S1 level of the host material is preferably higher than that of the TADF material. Furthermore, the T1 level of the host material is preferably higher than that of the TADF material.

[0238] Various charge transport materials can be used as host material in the light-emitting layer, such as materials with an electron transport property and / or materials with a hole transport property and the TADF materials.

[0239] The material having a hole-transport property is preferably, for example, an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton. As the π-electron-rich heteroaromatic ring, a condensed aromatic ring having at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton is preferred; in particular, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further condensed with a carbazole ring or a dibenzothiophene ring is preferred.

[0240] Such an organic compound having a hole-transport property more preferably has any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. Specifically, an aromatic amine having a substituent including a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group can be used. Note that the organic compound having a hole-transport property preferably has an N,N-bis(4-biphenyl)amino group to enable the fabrication of a light-emitting device with a long lifetime.

[0241] Examples of such an organic compound include compounds having an aromatic amine skeleton, such as4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-Diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-Bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-Diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF) and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluoren]-2-amine (abbreviation: PCBASF); compounds with a carbazole skeleton, such as B.1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP) and 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP); compounds with a thiophene skeleton, such as B. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV); and compounds with a furan skeleton, such as B. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II).Among the above materials, the compound with an aromatic amine skeleton and the compound with a carbazole skeleton are preferred because these compounds are highly reliable, exhibit high hole-transport properties, and contribute to a reduction in operating voltage. In addition, organic compounds can also be used, which are given as examples of the material with a hole-transport property that can be used for the hole-transport layer.

[0242] As a material with an electron transport property, for example, a metal complex such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) or bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ); or an organic compound having a π-electron-deficient heteroaromatic ring is preferably used.Examples of the organic compound having a π-electron-deficient heteroaromatic ring skeleton include an organic compound having a heteroaromatic ring with an azole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0243] Among the above materials, the organic compound having a heteroaromatic ring with a diazine skeleton (a pyrimidine skeleton, a pyrazine skeleton, or a pyridazine skeleton), the organic compound having a heteroaromatic ring with a pyridine skeleton, and the organic compound having a heteroaromatic ring with a triazine skeleton have high reliability and are therefore preferred. In particular, the organic compound having a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and the organic compound having a heteroaromatic ring with a triazine skeleton have high electron transport properties, contributing to a reduction in operating voltage.A benzofuropyrimidine scaffold, a benzothienopyrimidine scaffold, a benzofuropyrazine scaffold, and a benzothienopyrazine scaffold are preferred due to their high electron acceptor property and high reliability.

[0244] Examples of the organic compound having a π-electron-deficient heteroaromatic ring skeleton include an organic compound having an azole skeleton, such as: B. 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II) or 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOS); an organic compound containing a heteroaromatic ring with a pyridine skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), 2,9-Di(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-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: mTpPPhen), 2-phenyl-9-(2-triphenylenyl)-1,10-phenanthroline (abbreviation: Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1-naphthalenyl]-1,10-phenanthroline (abbreviation: PnNPhen) or 2-[4-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: pTpPPhen); an organic compound with a diazine skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-dibenzothiophen-4-yl)biphenyl-3-yl-]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 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), 6-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[(3'-(Dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-Bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-Bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-Bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[Pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(Biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm),8-[3'-(Dibenzothiophen-4-yl)(1,1'-biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-Binaphthalene)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(Pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(Pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(Biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-Bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-Bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(1,1'-biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm) or 7-[4-(9-Phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz); and an organic compound having a heteroaromatic ring with a triazine skeleton, such as 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazin (Abkürzung: BP-SFTzn), 2-{3-[3-(Benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazin (Abkürzung: mBnfBPTzn), 2-{3-[3-(Benzo[b]naphtho[1,2-a]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazin (Abkürzung: mBnfBPTzn-02), 2-{4-[3-(N-Phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazin (Abkürzung: PCCzPTzn), 9-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazol (Abkürzung: mPCCzPTzn-02), 2-[3'-(9,9-Dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazin (Abkürzung: mFBPTzn), 5-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazol (Abkürzung: mlNc(II)PTzn), 2-{3-[3-(Dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazin (Abkürzung: mDBtBPTzn), 2,4,6-Tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazin (Abkürzung: TmPPPyTz), 2-[3-(2,6-Dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazin (Abkürzung: mPnmDMePyPTzn),11-[4-(Biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(Triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-Diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn) or 2-(Biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn). The organic compound having a heteroaromatic ring with a diazine skeleton, the organic compound having a heteroaromatic ring with a pyridine skeleton, and the organic compound having a heteroaromatic ring with a triazine skeleton are preferred due to their high reliability. In particular, the organic compound having a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and the organic compoundwhich has a heteroaromatic ring with a triazine skeleton, has a high electron transport property to contribute to a reduction in operating voltage.

[0245] An organic compound with a bipolar property, such as 3,6-bis(diphenylamino)-9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9H-carbazole (abbreviation: DACT-II) or 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq), can also be used.

[0246] The materials mentioned above can also be used as TADF materials for use as host materials. When the TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted into singlet excitation energy through reverse intersystem crossing and transferred to the light-emitting substance, thereby increasing the emission efficiency of the light-emitting device. Here, the TADF material serves as the energy donor, and the light-emitting substance serves as the energy acceptor.

[0247] This is very effective when the light-emitting substance is a fluorescent substance. In this case, the S1 level of the TADF material is preferably higher than that of the fluorescent substance to achieve high emission efficiency. Furthermore, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent substance. Therefore, the T1 level of the TADF material is preferably higher than that of the fluorescent substance.

[0248] A TADF material that emits light whose wavelength overlaps with the wavelength of an absorption band on the lowest energy side of the fluorescent substance is also preferable. This allows the excitation energy to be smoothly transferred from the TADF material to the fluorescent substance, thus efficiently achieving light emission, which is preferable.

[0249] Charge carrier recombination preferably occurs in the TADF material to efficiently generate the singlet excitation energy from the triplet excitation energy through reverse intersystem crossing. It is also preferred that the triplet excitation energy generated in the TADF material not be transferred to the triplet excitation energy of the fluorescent substance. For this reason, the fluorescent substance preferably has a protecting group around a luminophore (a scaffold that generates light emission) of the fluorescent substance. A substituent without a π bond and a saturated hydrocarbon are preferably used as the protecting group. Specific examples include an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms.It is more preferable for the fluorescent substance to have a plurality of protecting groups. Substituents that do not have a π bond have poor charge carrier transport properties, allowing the TADF material and the luminophore of the fluorescent substance to be separated from each other with little effect on charge carrier transport or charge carrier recombination. Here, a luminophore refers to an atomic group (a skeleton) that generates light emission in a fluorescent substance. The luminophore is preferably a skeleton with a π bond, more preferably an aromatic ring, and even more preferably a condensed aromatic ring or a condensed heteroaromatic ring.Examples of the luminophore include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, and a naphthobisbenzofuran skeleton. In particular, a fluorescent substance having any of a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, and a naphthobisbenzofuran skeleton is preferred due to its high fluorescence quantum yield.

[0250] When a fluorescent substance is used as a light-emitting substance, a material having an anthracene skeleton is suitably used as the host material. Using a substance having an anthracene skeleton as the host material for the fluorescent substance enables the formation of a light-emitting layer with high emission efficiency and high durability. Among the substances having an anthracene skeleton, a substance having a diphenylanthracene skeleton, particularly a substance having a 9,10-diphenylanthracene skeleton, is chemically stable and is thus preferably used as the host material.The host material preferably has a carbazole framework because the hole injection and hole transport properties are improved; more preferably, the host material has a benzocarbazole framework in which a benzene ring is further condensed to a carbazole framework because its HOMO level is approximately 0.1 eV shallower than that of the host material having a carbazole framework, and therefore holes easily penetrate into the host material. Specifically, the host material preferably has a dibenzocarbazole framework because its HOMO level is approximately 0.1 eV shallower than that of the host material having a carbazole framework, so holes easily penetrate into the host material, improving the hole transport property and increasing the heat resistance. Consequently, a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole or dibenzocarbazole skeleton) is more preferred as a host material.It should be noted that in view of the hole injection and hole transport properties described above, a benzofluorene framework or a dibenzofluorene framework can be used instead of a carbazole framework.Examples of such a substance include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-Phenyl-10-[4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl]anthracene (abbreviation: FLPPA), 9-(1-Naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 9-(1-Naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-Phenylanthracen-9-yl)dibenzofuran, 2-(10-Phenyl-9-anthracenyl)benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-Naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βNmβNPAnth) and 1-{4-[10-(biphenyl-4-yl)-9-anthracenyl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA).In particular, CzPA, cgDBCzPA, 2mBnfPPA and PCzPA have excellent properties and are therefore preferentially selected.

[0251] Note that the host material may be a mixture of several types of substances; in the case of using a mixed host material, it is preferable to mix a material having an electron-transport property with a material having a hole-transport property. By mixing the material having an electron-transport property with the material having a hole-transport property, the transport property of the light-emitting layer 113 can be easily adjusted and a recombination range can be easily controlled. The weight ratio of the content of the material having a hole-transport property to the content of the material having an electron-transport property is 1:19 to 19:1.

[0252] It should be noted that a phosphorescent substance can be used as part of the mixed material. When a fluorescent substance is used as the light-emitting substance, a phosphorescent substance can be used as an energy donor to supply excitation energy to the fluorescent substance.

[0253] An exciplex can be formed from these mixed materials. These mixed materials are preferably selected to form an exciplex that emits light whose wavelength overlaps with the wavelength of an absorption band on the lowest energy side of the light-emitting substance. In this case, energy can be smoothly transferred and light emission can be efficiently achieved. The use of such a structure is preferred because the operating voltage can also be reduced.

[0254] It should be noted that at least one of the materials forming an exciplex can be a phosphorescent substance. In this case, the triplet excitation energy can be efficiently converted into the singlet excitation energy by reverse intersystem crossing.

[0255] To efficiently form an exciplex, a material with electron-transport properties is preferably combined with a material with hole-transport properties that has a HOMO level higher than or equal to that of the material with electron-transport properties. Furthermore, the LUMO level of the material with hole-transport properties is preferably higher than or equal to that of the material with electron-transport properties. Note that the LUMO levels and HOMO levels of the materials can be obtained from the electrochemical properties (reduction potentials and oxidation potentials) of the materials measured by cyclic voltammetry (CV).

[0256] The formation of an exciplex can be confirmed, for example, by a phenomenon in which the emission spectrum of the mixed film in which the material with a hole-transport property and the material with an electron-transport property are mixed is shifted to the longer wavelength side than the emission spectrum of each of the materials (or the emission spectrum has a different peak on the longer wavelength side), which phenomenon is observed by comparing the emission spectra of the material with a hole-transport property, the material with an electron-transport property, and the mixed film of these materials. Alternatively, the formation of an exciplex can be confirmed by a difference in the transient response, such asA phenomenon in which the transient photoluminescence (PL) lifetime of the blend film has components with longer lifetimes or a larger proportion of retardation components than that of either material can be confirmed, with the difference observed by comparing the transient PL of the material with a hole-transport property, the material with an electron-transport property, and the blend film of these materials. The transient PL can be reformulated as transient electroluminescence (EL). That is, the formation of an exciplex can also be confirmed by a difference in the transient response observed by comparing the transient EL of the material with a hole-transport property, the material with an electron-transport property, and the blend film of these materials.

[0257] The light-emitting layer 113 preferably contains, as a host material, the third organic compound having a third π-electron-deficient heteroaromatic ring. The third π-electron-deficient heteroaromatic ring is preferably identical to the second π-electron-deficient heteroaromatic ring of the second organic compound contained in the first layer of the intermediate layer. More preferably, the third organic compound is identical to the second organic compound.

[0258] The electron-transport layers 114 (the first electron-transport layer 114_1 and the second electron-transport layer 114_2) each contain a material having an electron-transport property. The material having an electron-transport property preferably has an electron mobility of greater than or equal to 1 × 10 -7 cm 2 / Vs, preferably higher than or equal to 1 × 10 -6 cm 2 / Vs in the case where the square root of the electric field strength [V / cm] is 600. Note that any other substance can be used as long as the substance has an electron-transport property higher than a hole-transport property. An organic compound having a π-electron-deficient heteroaromatic ring is preferable as the above organic compound. The organic compound having a π-electron-deficient heteroaromatic ring is preferably one or more of an organic compound having a heteroaromatic ring with an azole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0259] As the organic compound having an electron-transport property that can be used in the first electron-transport layer 114_1 and the second electron-transport layer 114_2, any of the above-mentioned organic compounds that can be used as the organic compound having an electron-transport property in the first light-emitting layer 113_1 and the second light-emitting layer 113_2 can be used. Among the above-mentioned materials, the organic compound having a heteroaromatic ring with a diazine skeleton, the organic compound having a heteroaromatic ring with a pyridine skeleton, and the organic compound having a heteroaromatic ring with a triazine skeleton are particularly preferred due to their high reliability.In particular, the organic compound having a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and the organic compound having a heteroaromatic ring with a triazine skeleton have a high electron transport property to contribute to a reduction in operating voltage. In particular, an organic compound having a phenanthroline ring skeleton, such as mTpPPhen, PnNPhen, or mPPhen2P, is preferred, and an organic compound having a phenanthroline dimer structure, such as mPPhen2P, is more preferred due to its excellent high stability.

[0260] The first electron transport layer preferably contains an organic compound with an electron transport property, wherein the acid constant pK s is less than 4.

[0261] The first electron-transport layer 114_1 and the second electron-transport layer 114_2 may each have a multilayer structure. In the case where the second electron-transport layer 114_2 has a multilayer structure, the layer in contact with the second light-emitting layer 113_2 may serve as a hole-blocking layer. In the case where the electron-transport layer in contact with the light-emitting layer serves as a hole-blocking layer, the electron-transport layer is preferably formed using a material having a HOMO level lower by more than or equal to 0.5 eV than a material included in the light-emitting layer.

[0262] The electron transport layer disposed between the light-emitting layer and the intermediate layer preferably contains an organic compound having a π-electron-deficient heteroaromatic ring and preferably differs from the organic compound having a π-electron-deficient heteroaromatic ring contained in the light-emitting layer. That is, Fig. 1 the first electron transport layer 114_1 preferably contains a fourth organic compound having a π-electron-deficient heteroaromatic ring and is preferably different from the third organic compound having the third π-electron-deficient heteroaromatic ring contained in the first light-emitting layer 113_1.

[0263] A layer containing an alkali metal, an alkaline earth metal or a compound thereof, such as lithium oxide (Li2O), lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2) or 8-hydroxyquinolinato-lithium (Liq), may be sandwiched between the electron transport layer closest to the second electrode 102 (the second electron transport layer 114_2 in Fig. 1), and the second electrode 102 as the electron-injection layer 115. An electride or a layer formed using a substance having an electron-transport property and containing an alkali metal, an alkaline earth metal, or a compound thereof can be used as the electron-injection layer 115. Examples of the electride include a substance in which electrons are added at a high concentration to calcium oxide-alumina.

[0264] The electron injection layer 115 may be formed using any of the above substances alone or using any of the above substances included in a layer containing a substance having an electron transport property.

[0265] Note that, as the electron-injection layer 115, a layer containing a substance with electron-transport properties (preferably an organic compound having a bipyridine skeleton) containing a fluoride of an alkali metal or alkaline earth metal at a concentration higher than or equal to that at which the electron-injection layer 115 becomes a microcrystalline state (50 wt% or higher) can be used. Since the layer has a low refractive index, a light-emitting device including the layer can exhibit favorable external quantum efficiency.

[0266] The second electrode 102 is an electrode that includes a cathode. The second electrode 102 may have a multilayer structure, in which case a layer that is in contact with the organic compound layer 103 serves as the cathode. For the cathode, a metal, an alloy, an electrically conductive compound, or a mixture thereof, each having a low work function (in particular, lower than or equal to 3.8 eV), or the like, may be used. Specific examples of such a cathode material include elements belonging to group 1 or 2 of the periodic table, such as, for example, B. Alkali metals (e.g. lithium (Li) or cesium (Cs)), magnesium (Mg), calcium (Ca) and strontium (Sr), alloys containing these elements (e.g. MgAg and AlLi), compounds containing these elements (e.g. lithium fluoride (LiF), cesium fluoride (CsF) and calcium fluoride (CaF2)), rare earth metals, such asEuropium (Eu) and ytterbium (Yb), and alloys containing these rare earth metals. However, when the electron injection layer 115 or a thin film formed using any of the above low work function materials is provided between the second electrode 102 and the electron transport layer, various conductive materials, such as Al, Ag, ITO, or indium oxide-tin oxide containing silicon or silicon oxide, can be used for the cathode regardless of the work function.

[0267] When the second electrode 102 is formed using a material that transmits visible light, the light-emitting device can emit light from the second electrode 102 side. When the first electrode 101 is formed using a material that transmits visible light, the light-emitting device can emit light from the first electrode 101 side.

[0268] Films of these conductive materials can be formed by a dry process such as a vacuum evaporation method or a sputtering method, an inkjet method, a spin-coating method, or the like. Alternatively, a wet process using a sol-gel method or a wet process using a paste of a metal material can be used.

[0269] The organic compound layer 103 can be formed by any of various methods including a dry process and a wet process. For example, a vacuum evaporation method, a gravure printing method, an offset printing method, a screen printing method, an inkjet method, a spin-coating method, or the like can be used.

[0270] Different film formation methods can be used to form the electrodes or layers described above.

[0271] The light-emitting device comprising two light-emitting units is identified by Fig. 1; however, an embodiment of the present invention can also be applied to a light-emitting device in which three or more light-emitting units are stacked. When a plurality of light-emitting units divided by the intermediate layer 116 are arranged between a pair of electrodes as in the light-emitting device of this embodiment, it is possible to provide a long-life element that can emit light with high luminance at a low current density. A light-emitting device that can be operated at a low voltage and has low power consumption can also be provided.

[0272] When the emission colors of the light-emitting units differ from each other, light emission of a desired color can be obtained from the light-emitting device as a whole. For example, in a light-emitting device comprising two light-emitting units, the emission colors of the first light-emitting unit may be red and green, and the emission color of the second light-emitting unit may be blue, so that the light-emitting device can emit white light as a whole.

[0273] The organic compound layer 103, the first light-emitting unit 501, the second light-emitting unit 502, the layers such as the carrier generation layer, and the electrodes described above can be formed by a method such as an evaporation method (including a vacuum evaporation method), a droplet ejection method (also referred to as an inkjet method), a coating method, or a gravure printing method. A low-molecular material, a medium-molecular material (including an oligomer and a dendrimer), or a high-molecular material can be included in the above components.

[0274] Fig. 2 illustrates two adjacent tandem light-emitting devices (a light-emitting device 130c and a light-emitting device 130d) fabricated by a photolithography technique.

[0275] The light-emitting device 130c includes an organic compound layer 103c between a first electrode 101c over an insulating layer 175 and the second electrode 102. The organic compound layer 103c has a structure in which a first light-emitting unit 501c and a second light-emitting unit 502c are arranged one above the other with an intermediate layer 116c therebetween. Although Fig. 2 illustrates an example in which the two light-emitting units are arranged one above the other, three or more light-emitting units may be arranged one above the other. The first light-emitting unit 501c comprises a hole-injection layer 111c, a first hole-transport layer 112c_1, a first light-emitting layer 113c_1, and a first electron-transport layer 114c_1. The intermediate layer 116c comprises a second region 117c, a third region 118c, and a first region 119c. The second light-emitting unit 502c comprises a second hole-transport layer 112c_2, a second light-emitting layer 113c_2, a second electron-transport layer 114c_2, and the electron-injection layer 115.

[0276] The light-emitting device 130d includes an organic compound layer 103d between a first electrode 101d over the insulating layer 175 and the second electrode 102. The organic compound layer 103d has a structure in which a first light-emitting unit 501d and a second light-emitting unit 502d are arranged one above the other with an intermediate layer 116d therebetween. Although Fig. While FIG. 2 illustrates an example in which the two light-emitting units are arranged one above the other, three or more light-emitting units may be arranged one above the other. The first light-emitting unit 501d comprises a hole-injection layer 111d, a first hole-transport layer 112d_1, a first light-emitting layer 113d_1, and an electron-transport layer 114d_1. The intermediate layer 116d comprises a second region 117d, a third region 118d, and a first region 119d. The second light-emitting unit 502d comprises a second hole-transport layer 112d_2, a second light-emitting layer 113d_2, a second electron-transport layer 114d_2, and the electron-injection layer 115.

[0277] In the light-emitting devices 130c and 130d, the intermediate layers 116c and 116d preferably have the structures described in Embodiment 1.

[0278] Note that each of the electron-injection layer 115 and the second electrode 102 is preferably a continuous layer shared by the light-emitting device 130c and the light-emitting device 130d. The layers other than the electron-injection layer 115 included in the organic compound layer 103c are independent of the layers other than the electron-injection layer 115 included in the organic compound layer 103d because they are processed by a photolithography technique after the formation of the second electron-transport layer 114c_2 and after the formation of the second electron-transport layer 114d_2. End portions (contours) of the layers other than the electron-injection layer 115 in the organic compound layer 103c are processed by a photolithography technique and are therefore substantially aligned in the direction perpendicular to the substrate.End portions (contours) of the layers other than the electron injection layer 115 in the organic compound layer 103d are processed by a photolithography technique and are therefore substantially aligned in the direction perpendicular to the substrate.

[0279] A gap d exists between the organic compound layer 103c and the organic compound layer 103d due to processing by a photolithography technique. Since the organic compound layers are processed by a photolithography technique, the distance between the first electrode 101c and the first electrode 101d can be made as small as greater than or equal to 0.5 μm and less than or equal to 5 μm compared to the case where mask evaporation is performed.

[0280] The light-emitting device of one embodiment of the present invention having the above-described structure can have high current efficiency, high reliability, and suppressed increase in operating voltage.

[0281] An embodiment of the present invention is particularly suitably used in a light-emitting device formed by a photolithography process, and also contributes to cost reduction in the manufacture of light-emitting devices not formed by a photolithography process, since high stability in the atmosphere of an embodiment of the present invention increases the yield and eliminates the need for overly strict control of the atmosphere in the manufacturing process. (Embodiment 3)

[0282] What is described in this embodiment is a mode in which the light-emitting device of one embodiment of the present invention is used as a display element of a display device.

[0283] As in Fig. 3A and Fig. 3B, a plurality of light-emitting devices 130 are formed over the insulating layer 175 to form a display device.

[0284] The display device includes a pixel section 177 in which a plurality of pixels 178 are arranged in a matrix. Pixel 178 includes a subpixel 110R, a subpixel 110G, and a subpixel 110B.

[0285] For example, in this specification and the like, explanations common to subpixels 110R, 110G, and 110B are sometimes described using the collective term "subpixel 110." Regarding other components that are distinguishable from each other using alphabetic letters, elements common to the components are sometimes described using reference numerals without the alphabetic letters.

[0286] Subpixel 110R emits red light, subpixel 110G emits green light, and subpixel 110B emits blue light. Therefore, a full-color image can be displayed on pixel portion 177. Note that, in this embodiment, three colors of red (R), green (G), and blue (B) are given as examples of colors of light emitted by the subpixels; however, subpixels of a different combination of colors may be used. The number of subpixels is not limited to three and may be four or more. Examples of four subpixels include subpixels emitting light of four colors of R, G, B, and white (W), subpixels emitting light of four colors of R, G, B, and yellow (Y), and four subpixels emitting light of R, G, B, and infrared (IR) light.

[0287] In this specification and the like, the row direction and column direction are sometimes referred to as the X direction and the Y direction, respectively. The X direction and the Y direction intersect each other and are perpendicular to each other, for example.

[0288] Fig. Figure 3A illustrates an example in which subpixels of different colors are arranged in the X direction and subpixels of the same color are arranged in the Y direction. Note that subpixels of different colors can be arranged in the Y direction, and subpixels of the same color can be arranged in the X direction.

[0289] A connecting portion 140 is provided outside the pixel portion 177, and a region 141 may also be provided. The region 141 is provided between the pixel portion 177 and the connecting portion 140. The organic interconnect layer 103 is provided in the region 141. A conductive layer 151C is provided in the connecting portion 140.

[0290] Although Fig. 3A illustrates an example in which the region 141 and the connecting portion 140 are located on the right side of the pixel portion 177, the positions of the region 141 and the connecting portion 140 are not particularly limited. The number of regions 141 and the number of connecting portions 140 may each be one or more.

[0291] Fig. Figure 3B is an example of a cross-sectional view along the dotted line A1-A2 in Fig. 3A. As in Fig. 3B, the display device includes an insulating layer 171, a conductive layer 172 over the insulating layer 171, an insulating layer 173 over the insulating layer 171 and the conductive layer 172, an insulating layer 174 over the insulating layer 173, and the insulating layer 175 over the insulating layer 174. The insulating layer 171 is provided over a substrate (not shown). An opening reaching the conductive layer 172 is provided in the insulating layers 175, 174, and 173, and a terminal plug 176 is provided to fill the opening.

[0292] In the pixel portion 177, the light-emitting device 130 is provided over the insulating layer 175 and the terminal plug 176. A protective layer 131 is provided to cover the light-emitting device 130. A substrate 120 is bonded to the protective layer 131 with a resin layer 122. An inorganic insulating layer 125 and an insulating layer 127 over the inorganic insulating layer 125 are preferably provided between the adjacent light-emitting devices 130.

[0293] Although Fig. 3B illustrates cross sections of a plurality of inorganic insulating layers 125 and a plurality of insulating layers 127. Preferably, the inorganic insulating layers 125 are connected to each other, and the insulating layers 127 are connected to each other when the display device is viewed from above. In other words, the insulating layer 127 preferably includes an opening portion above a first electrode.

[0294] In Fig. 3B, a light-emitting device 130R, a light-emitting device 130G, and a light-emitting device 130B are illustrated as light-emitting devices 130. The light-emitting devices 130R, 130G, and 130B emit light of different colors. For example, the light-emitting device 130R may emit red light, the light-emitting device 130G may emit green light, and the light-emitting device 130B may emit blue light. Alternatively, the light-emitting device 130R, 130G, or 130B may emit visible light of another color or infrared light.

[0295] The display device of one embodiment of the present invention may, for example, be a top-emission display device in which light is emitted in the direction opposite to a substrate over which light-emitting devices are formed. Note that the display device of one embodiment of the present invention may be a bottom-emission display device.

[0296] The light-emitting device 130R has a structure described in Embodiments 1 and 2. The light-emitting device 130R includes a first electrode 101R (pixel electrode) comprising a conductive layer 151R and a conductive layer 152R, a first EL layer 104R over the first electrode 101R, an organic compound layer (a second EL layer 105 over the first EL layer 104R), and the second electrode 102 (common electrode) over the second EL layer 105. The second EL layer 105 is preferably positioned closer to the second electrode 102 (common electrode) side than the light-emitting layer, and is preferably a hole-blocking layer, a second electron-transporting layer, an electron-injecting layer, or stacked layers thereof.Such a structure can reduce damage to the light-emitting layer or an active layer during a photolithography process, promising favorable film quality and electrical properties.

[0297] The light-emitting device 130G has a structure described in Embodiments 1 and 2. The light-emitting device 130G includes a first electrode 101G (pixel electrode) comprising a conductive layer 151G and a conductive layer 152G, a first EL layer 104G over the first electrode 101G, the second EL layer 105 over the first EL layer 104G, and the second electrode 102 (common electrode) over the second EL layer 105. The second EL layer 105 is preferably a hole-blocking layer, a second electron-transporting layer, an electron-injecting layer, or stacked layers thereof.

[0298] The light-emitting device 130B has a structure described in Embodiments 1 and 2. The light-emitting device 130B includes a first electrode 101B (pixel electrode) comprising a conductive layer 151B and a conductive layer 152B, a first EL layer 104B over the first electrode 101B, the second EL layer 105 over the first EL layer 104B, and the second electrode 102 (common electrode) over the second EL layer 105. The second EL layer 105 is preferably a hole-blocking layer, a second electron-transporting layer, an electron-injecting layer, or stacked layers thereof.

[0299] In the light-emitting device, one of the pixel electrode (the first electrode) and the common electrode (the second electrode) serves as the anode, and the other serves as the cathode. In this embodiment, the description is made assuming that the pixel electrode serves as the anode and the common electrode serves as the cathode, unless otherwise specified.

[0300] The first EL layers 104R, 104G, and 104B are island-shaped layers that are independent of each other based on a light-emitting device or based on an emission color. It is preferable that the first EL layers 104R, 104G, and 104B do not overlap each other. By providing the island-shaped first EL layer 104 in each of the light-emitting devices 130, leakage current between the adjacent light-emitting devices 130 can be prevented even in a high-resolution display device. This can prevent crosstalk, so that a display device with very high contrast can be obtained. In particular, a display device with high current efficiency at low luminance can be obtained.

[0301] The island-shaped first EL layer 104 can be formed by forming an EL film and processing the EL film by a photolithography technique.

[0302] In the display device of one embodiment of the present invention, the first electrode 101 (pixel electrode) of the light-emitting device preferably has a multi-layer structure. For example, in the Fig. 3B, the first electrode 101 of the light-emitting device 130 comprises a layer arrangement of the conductive layer 151 on the side of the insulating layer 171 and the conductive layer 152 on the side of the organic compound layer.

[0303] A metal material can be used, for example, for the conductive layer 151. In particular, it is possible to use, for example, a metal such as 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), or neodymium (Nd), or an alloy containing a suitable combination of any of these metals.

[0304] For the conductive layer 152, an oxide containing one or more of indium, tin, zinc, gallium, titanium, aluminum, and silicon may be used. For example, a conductive oxide containing one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, indium zinc oxide containing silicon, and the like is preferably used. In particular, indium tin oxide containing silicon can be suitably used for the conductive layer 152 because it has, for example, a high work function, such as a work function greater than or equal to 4.0 eV.

[0305] The conductive layer 151 and the conductive layer 152 may each be a stack of layers containing a plurality of different materials. In this case, the conductive layer 151 may include a layer formed using a material that can be used for the conductive layer 152, such as a conductive oxide, and the conductive layer 152 may include a layer formed using a material that can be used for the conductive layer 151, such as a metal material. In the case where the conductive layer 151 is a stack of two or more layers, for example, a layer in contact with the conductive layer 152 may be formed using a material that can be used for the conductive layer 152.

[0306] The conductive layer 151 preferably has a tapered end portion. In particular, the conductive layer 151 preferably has a tapered end portion with a taper angle of less than 90°. In this case, the conductive layer 152 provided along the side surface of the conductive layer 151 also has a tapered shape. If the side surface of the conductive layer 152 has a tapered shape, the coverage with the first EL layer 104 provided along the side surface of the conductive layer 152 can be improved.

[0307] Since the light-emitting device 130 has the structure described in Embodiments 1 and 2, the display device of one embodiment of the present invention can have high moisture resistance, high water resistance, high oxygen resistance, high chemical resistance, low operating voltage, and high emission efficiency.

[0308] Next, an example of a method for manufacturing the display device having the Fig. 3A shown structure using Fig. 4A to Fig. 4E, Fig. 5A to Fig. 5D, Fig. 6A to Fig. 6D, Fig. 7A to Fig. 7C, Fig. 8A to Fig. 8C and Fig. 9A to Fig. 9C described. [Example 1 of the manufacturing process]

[0309] Thin films included in the display device (e.g., insulating films, semiconductor films, and conductive films) can be formed by a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, or the like.

[0310] Thin films included in the display device (e.g., insulating films, semiconductor films, and conductive films) can also be formed by a wet process such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor blade coating, slot coating, roll coating, curtain coating, or knife coating.

[0311] Thin films included in the display device can be processed, for example, by a photolithography technique.

[0312] For example, the light used for exposure in photolithography can be i-line light (wavelength: 365 nm), g-line light (wavelength: 436 nm), h-line light (wavelength: 405 nm), or light in which the i-line, g-line, and h-line are mixed. Alternatively, ultraviolet rays, KrF laser light, ArF laser light, or the like can be used. Exposure can be performed by a liquid immersion exposure technique. Extreme ultraviolet (EUV) light or X-rays can also be used as the light for exposure. Furthermore, an electron beam can be used instead of the light used for exposure.

[0313] To etch thin films, a dry etching method, a wet etching method, a sandblasting method, or the like can be used.

[0314] First, as in Fig. 4A, the insulating layer 171 is formed over a substrate (not shown). Next, the conductive layer 172 and a conductive layer 179 are formed over the insulating layer 171, and the insulating layer 173 is formed over the insulating layer 171 so as to cover the conductive layer 172 and the conductive layer 179. Then, the insulating layer 174 is formed over the insulating layer 173, and the insulating layer 175 is formed over the insulating layer 174.

[0315] As the substrate, a substrate with high enough heat resistance to withstand at least one subsequent heat treatment can be used. For example, it is possible to use a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or a semiconductor substrate such as a single-crystal semiconductor substrate or a polycrystalline semiconductor substrate made of silicon, silicon carbide, or the like, a compound semiconductor substrate made of silicon germanium or the like, or an SOI substrate.

[0316] Next, as in Fig. As shown in Figure 4A, openings reaching the conductive layer 172 are formed in the insulating layers 175, 174, and 173. Then, the terminal plugs 176 are formed to fill the openings.

[0317] Next, as in Fig.As shown in Figure 4A, a conductive film 151f, which becomes the conductive layers 151R, 151G, 151B, and 151C, is formed over the terminal plug 176 and the insulating layer 175. For the conductive film 151f, for example, a metal material can be used.

[0318] Then a lacquer mask 191, as in Fig. 4A, is formed over the conductive film 151f. The resist mask 191 can be formed by applying a light-sensitive material (photoresist), exposing it, and developing it.

[0319] Then, as in Fig. 4B, the conductive film 151f is removed, for example, in an area that does not overlap with the resist mask 191. In this way, the conductive layer 151 is formed.

[0320] Next, the resist mask 191 is removed as shown in Fig. 4C. The resist mask 191 can be removed, for example, by ashing using oxygen plasma.

[0321] Then, as in Fig. 4D, an insulating film 156f, which becomes an insulating layer 156R, an insulating layer 156G, an insulating layer 156B, and an insulating layer 156C, is formed over the conductive layer 151R, the conductive layer 151G, the conductive layer 151B, the conductive layer 151C, and the insulating layer 156F.

[0322] As the insulating film 156f, an inorganic insulating film such as an insulating oxide film, an insulating nitride film, an insulating oxynitride film, or an insulating nitride oxide film such as silicon oxynitride can be used.

[0323] Then, as in Fig. 4E, the insulating film 156f is processed to form the insulating layers 156R, 156G, 156B and 156C.

[0324] Next, as in Fig.5A, a conductive film 152f is formed over the conductive layers 151R, 151G, 151B and 151C and the insulating layers 156R, 156G, 156B, 156C and 156S.

[0325] For example, a conductive oxide can be used for the conductive film 152f. The conductive film 152f can have a multilayer structure.

[0326] Then, as in Fig. 5B, the conductive film 152f is processed to form the conductive layers 152R, 152G, 152B, and 152C.

[0327] Next, as in Fig. 5C, an organic compound film 103Rf is formed over the conductive layers 152R, 152G and 152B and the insulating layer 175. As shown in Fig. 5C, the organic compound film 103Rf is not formed over the conductive layer 152C.

[0328] Then a sacrificial film 158Rf and a mask film 159Rf are formed as in Fig. 5C.

[0329] By providing the sacrificial film 158Rf over the organic compound film 103Rf, damage to the organic compound film 103Rf in the manufacturing process of the display device can be reduced, resulting in an increase in the reliability of the light-emitting device.

[0330] For the sacrificial film 158Rf, a film with high resistance to the process conditions for the organic compound film 103Rf is used, particularly a film with high etch selectivity with respect to the organic compound film 103Rf. For the mask film 159Rf, a film with high etch selectivity with respect to the sacrificial film 158Rf is used.

[0331] The sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the upper temperature limit of the organic compound film 103Rf. Typical substrate temperatures during the formation of the sacrificial film 158Rf and the mask film 159Rf are respectively higher than or equal to 100°C and lower than or equal to 200°C, preferably higher than or equal to 100°C and lower than or equal to 150°C, more preferably higher than or equal to 100°C and lower than or equal to 120°C.

[0332] The sacrificial film 158Rf and the mask film 159Rf are preferably films that can be removed by a wet etching process or a dry etching process.

[0333] Note that the sacrificial film 158Rf formed over and in contact with the organic compound film 103Rf is preferably formed by a formation method that is less likely to damage the organic compound film 103Rf than the formation method of the mask film 159Rf. For example, the sacrificial film 158Rf is preferably formed by an atomic layer deposition (ALD) method or an evaporation method rather than a sputtering method.

[0334] As both the sacrificial film 158Rf and the mask film 159Rf, for example, one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, and an inorganic insulating film can be used.

[0335] For each of the sacrificial film 158Rf and the mask film 159Rf, for example, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing any of the metal materials, can be used. In particular, a low-melting material such as aluminum or silver is preferably used. Preferably, a metal material capable of blocking ultraviolet rays is used for the sacrificial film 158Rf and / or the mask film 159Rf. In this case, the organic compound film 103Rf can be prevented from being irradiated with ultraviolet rays during exposure for patterning, and deterioration of the organic compound film 103Rf can be prevented.

[0336] The sacrificial film 158Rf and the mask film 159Rf can each be formed using a metal oxide such as In-Ga-Zn oxide, indium oxide, In-Zn 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), or indium tin oxide containing silicon.

[0337] In the above metal oxide, an element M (M is one or more of aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten and magnesium) may be used instead of gallium.

[0338] The sacrificial film 158Rf and the mask film 159Rf are preferably formed using a semiconductor material such as silicon or germanium for excellent compatibility with a semiconductor manufacturing process. Alternatively, a compound containing the above semiconductor material may be used.

[0339] Any of various inorganic insulating films can be used as both the sacrificial film 158Rf and the mask film 159Rf. In particular, an insulating oxide film is preferred because its adhesion to the organic compound film 103Rf is higher than that of an insulating nitride film.

[0340] A resist mask 190R is then formed, as shown in Fig. 5C. The resist mask 190R can be formed by applying a light-sensitive material (photoresist), exposure, and development.

[0341] The resist mask 190R is provided in a position that overlaps with the conductive layer 152R. The resist mask 190R is preferably also provided in a position that overlaps with the conductive layer 152C. This can prevent the conductive layer 152C from being damaged during the manufacturing process of the display device.

[0342] Next, as in Fig. 5D, a portion of the mask film 159Rf is removed using the resist mask 190R, so that a mask layer 159R is formed. The mask layer 159R remains over the conductive layers 152R and 152C. Thereafter, the resist mask 190R is removed. Then, a portion of the sacrificial film 158Rf is removed using the mask layer 159R as a mask (also called a hard mask), so that a sacrificial layer 158R is formed.

[0343] Using a wet etching method can reduce damage to the organic compound film 103Rf during the processing of the sacrificial film 158Rf and the mask film 159Rf compared to the case of using a dry etching method. When using a wet etching method, it is preferable to use, for example, a developing solution, an alkaline aqueous solution such as an aqueous tetramethylammonium hydroxide (TMAH) solution, diluted hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or an acidic aqueous solution such as a chemical solution containing a mixed solution of any of these acids.

[0344] In case of using a dry etching method to process the sacrificial film 158Rf, the deterioration of the organic compound film 103Rf can be prevented without using a gas containing oxygen as an etching gas.

[0345] The resist mask 190R can be removed by a similar procedure to that for the resist mask 191.

[0346] Next, as in Fig. 5D, the organic interconnection film 103Rf is processed to form an organic interconnection layer 103R. For example, a part of the organic interconnection film 103Rf is removed using the mask layer 159R and the sacrificial layer 158R as a hard mask, thereby forming the organic interconnection layer 103R.

[0347] Consequently, the multilayer structure of the organic interconnect layer 103R, the sacrificial layer 158R and the mask layer 159R remains as shown in Fig. 5D, over the conductive layer 152R. The conductive layers 152G and 152B are exposed.

[0348] The organic compound film 103Rf is preferably processed by anisotropic etching. Anisotropic dry etching is particularly preferred. Alternatively, wet etching can be used.

[0349] In case of using a dry etching method, the deterioration of the organic compound film 103Rf can be prevented without using a gas containing oxygen as an etching gas.

[0350] A gas containing oxygen can be used as the etching gas. When the etching gas contains oxygen, the etching rate can be increased. Therefore, etching can be performed under low-power conditions while maintaining a sufficiently high etching rate. Accordingly, damage to the organic compound film 103Rf can be reduced. Furthermore, defects such as the adhesion of a reaction product generated during etching can be prevented.

[0351] When using a dry etching method, it is preferable to use a gas containing, for example, at least one of H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, and a Group 18 element such as He or Ar as the etching gas. Alternatively, a gas containing oxygen and at least one of the above is preferably used as the etching gas. Alternatively, an oxygen gas may be used as the etching gas.

[0352] Then, as in Fig. 6A, an organic compound film 103Gf, which becomes an organic compound layer 103G, is formed.

[0353] The organic compound film 103Gf can be formed by a similar method to that used to form the organic compound film 103Rf. The organic compound film 103Gf can have a similar structure to that of the organic compound film 103Rf.

[0354] Then, as in Fig.As shown in Figure 6A, a sacrificial film 158Gf and a mask film 159Gf are formed in this order. Next, a resist mask 190G is formed. The materials and formation methods of the sacrificial film 158Gf and the mask film 159Gf are similar to those of the sacrificial film 158Rf and the mask film 159Rf. The material and formation method of the resist mask 190G are similar to those of the resist mask 190R.

[0355] The resist mask 190G is provided in a position overlapping with the conductive layer 152G.

[0356] Then, as in Fig.6B, a portion of the mask film 159Gf is removed using the resist mask 190G, so that a mask layer 159G is formed. The mask layer 159G remains above the conductive layer 152G. Thereafter, the resist mask 190G is removed. Then, a portion of the sacrificial film 158Gf is removed using the mask layer 159G as a mask, so that a sacrificial layer 158G is formed. Next, the organic compound film 103Gf is processed to form the organic compound layer 103G. Accordingly, as shown in Fig. 6B illustrates the multilayer structure of the organic interconnect layer 103G, the sacrificial layer 158G, and the mask layer 159G over the conductive layer 152G. The mask layer 159R and the conductive layer 152B are exposed.

[0357] Then, as in Fig. 6C, an organic compound film 103Bf was formed.

[0358] The organic compound film 103Bf may be formed by a method similar to that used to form the organic compound film 103Rf. The organic compound film 103Bf may have a structure similar to that of the organic compound film 103Rf.

[0359] Then, as in Fig. 6C, a sacrificial film 158Bf and a mask film 159Bf are formed in this order. Next, a resist mask 190B is formed. The materials and formation methods of the sacrificial film 158Bf and the mask film 159Bf are similar to those of the sacrificial film 158Rf and the mask film 159Rf. The material and formation method of the resist mask 190B are similar to those of the resist mask 190R.

[0360] The resist mask 190B is provided in a position overlapping with the conductive layer 152B.

[0361] Then, as in Fig.6D, a part of the mask film 159Bf is removed using the resist mask 190B, so that a mask layer 159B is formed. The mask layer 159B remains over the conductive layer 152B. After that, the resist mask 190B is removed. Then, a part of the sacrificial film 158Bf is removed using the mask layer 159B as a mask, so that a sacrificial layer 158B is formed. Next, the organic compound film 103Bf is processed to form an organic compound layer 103B. For example, a part of the organic compound film 103Bf is removed using the mask layer 159B and the sacrificial layer 158B as a hard mask, thereby forming the organic compound layer 103B.

[0362] Consequently, as in Fig.6D shows the multilayer structure of the organic interconnect layer 103B, the sacrificial layer 158B, and the mask layer 159B over the conductive layer 152B. The mask layers 159R and 159G are exposed.

[0363] It should be noted that the side surfaces of the organic compound layers 103R, 103G, and 103B are preferably perpendicular or substantially perpendicular to their formation surfaces. For example, the angle between the formation surfaces and these side surfaces is preferably greater than or equal to 60° and less than or equal to 90°.

[0364] The distance between two adjacent layers among the organic compound layers 103R, 103G, and 103B formed by a photolithography technique as described above can be reduced to less than or equal to 8 µm, less than or equal to 5 µm, less than or equal to 3 µm, less than or equal to 2 µm, or less than or equal to 1 µm. Here, the distance can be determined, for example, by the distance between opposite end portions of the two adjacent layers among the organic compound layers 103R, 103G, and 103B. Reducing the distance between the island-shaped organic compound layers makes it possible to provide a display device with high resolution and a high aperture ratio.Furthermore, the distance between the first electrodes of adjacent light-emitting devices can also be reduced, for example, to less than or equal to 10 µm, less than or equal to 8 µm, less than or equal to 5 µm, less than or equal to 3 µm, or less than or equal to 2 µm. Note that the distance between the first electrodes of adjacent light-emitting devices is preferably greater than or equal to 2 µm and less than or equal to 5 µm.

[0365] Next, as in Fig. 7A, the mask layers 159R, 159G and 159B are preferably removed.

[0366] The mask layer removal step can be performed using a method similar to that used for the mask film processing step. In particular, the damage to the organic compound layer 103 during mask layer removal can be reduced by using a wet etching method compared to the case of using a dry etching method.

[0367] The mask layers can be removed by dissolving them in a polar solvent, such as water or an alcohol. Examples of alcohols include ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), and glycerin.

[0368] After the mask layers have been removed, a drying treatment can be performed to remove water adsorbed on surfaces. For example, a heat treatment can be performed in an inert gas atmosphere or in a reduced-pressure atmosphere. The heat treatment can be performed at a substrate temperature of greater than or equal to 50°C and less than or equal to 200°C, preferably greater than or equal to 60°C and less than or equal to 150°C, more preferably greater than or equal to 70°C and less than or equal to 120°C. The heat treatment is preferably performed in a reduced-pressure atmosphere, in which case drying at a lower temperature is possible.

[0369] Next, an inorganic insulating film 125f is formed as shown in Fig. 7B.

[0370] Then, as in Fig.7C, an insulating film 127f, which becomes the insulating layer 127, is formed over the inorganic insulating film 125f.

[0371] The substrate temperature in the formation of the inorganic insulating film 125f and the insulating film 127f is preferably higher than or equal to 60 °C, higher than or equal to 80 °C, higher than or equal to 100 °C, or higher than or equal to 120 °C and lower than or equal to 200 °C, lower than or equal to 180 °C, lower than or equal to 160 °C, lower than or equal to 150 °C, or lower than or equal to 140 °C.

[0372] As the inorganic insulating film 125f, an insulating film having a thickness of greater than or equal to 3 nm, greater than or equal to 5 nm, or greater than or equal to 10 nm and less than or equal to 200 nm, less than or equal to 150 nm, less than or equal to 100 nm, or less than or equal to 50 nm is preferably formed at a substrate temperature in the above-described range.

[0373] The inorganic insulating film 125f is preferably formed, for example, by an ALD method. An ALD method is preferably used, in which case deposition damage is reduced and a film with good coverage can be formed. As the inorganic insulating film 125f, an alumina film is preferably formed, for example, by an ALD method.

[0374] The insulating film 127f is preferably formed by the aforementioned wet process. The insulating film 127f is preferably formed, for example, by spin coating using a photosensitive material, and particularly preferably using a photosensitive resin composition containing an acrylic resin.

[0375] Then, a portion of the insulating film 127f is exposed to visible light or ultraviolet rays. The insulating layer 127 is formed in regions located between any two of the conductive layers 152R, 152G, and 152B, and around the conductive layer 152C.

[0376] The width of the insulating layer 127 to be formed later can be controlled according to the exposed area of ​​the insulating film 127f. In this embodiment, processing is performed such that the insulating layer 127 includes a portion overlapping with the upper surface of the conductive layer 151.

[0377] The light used for exposure preferably contains the i-line (wavelength: 365 nm). Furthermore, the light used for exposure may contain at least one of the g-line (wavelength: 436 nm) and the h-line (wavelength: 405 nm).

[0378] Next, the exposed area of ​​the insulating film 127f is removed by development as shown in Fig. 8A, so that an insulating layer 127a is formed.

[0379] Next, as in Fig. 8B, an etching treatment is performed using the insulating layer 127a as a mask to remove a portion of the inorganic insulating film 125f and reduce the thickness of a portion of the sacrificial layers 158R, 158G, and 158B. Therefore, the inorganic insulating layer 125f is formed under the insulating layer 127a. Furthermore, the surfaces of the thin portions in the sacrificial layers 158R, 158G, and 158B are exposed. Note that the etching treatment using the insulating layer 127a as a mask may be referred to as the first etching treatment hereinafter.

[0380] The first etching treatment can be performed by dry etching or wet etching. Note that the inorganic insulating film 125f is preferably formed using a similar material to that of the sacrificial layers 158R, 158G, and 158B, in which case the first etching treatment can be performed simultaneously.

[0381] When performing dry etching, a chlorine-based gas is preferably used. As the chlorine-based gas, one of Cl2, BCl3, SiCl4, CCl4, and the like, or a mixture of two or more of them, can be used. Furthermore, an oxygen gas, a hydrogen gas, a helium gas, an argon gas, or the like, or a mixture of two or more of them, can be added to the chlorine-based gas as needed. By dry etching, the thin portions of the sacrificial layers 158R, 158G, and 158B can be formed with favorable in-plane uniformity.

[0382] A dry etching device comprising a high-density plasma source can be used as the dry etching device. For example, an inductively coupled plasma (ICP) etching device can be used as the dry etching device comprising a high-density plasma source. Alternatively, a capacitively coupled plasma (CCP) etching device comprising parallel plate electrodes can be used.

[0383] The first etching treatment is preferably performed by wet etching. Using a wet etching method can reduce damage to the organic compound layers 103R, 103G, and 103B compared to the case of using a dry etching method. The wet etching can be performed using, for example, an alkaline solution. For example, TMAH, which is an alkaline solution, can be used for the wet etching of an aluminum oxide film. Alternatively, an acid solution containing fluoride can also be used. In this case, a puddle wet etching can be performed. Note that the inorganic insulating film 125f is preferably formed using a material similar to that of the sacrificial layers 158R, 158G, and 158B, in which case the above etching treatment can be performed simultaneously.

[0384] The sacrificial layers 158R, 158G, and 158B are not completely removed by the first etching treatment, and the etching treatment is stopped when the thickness of the sacrificial layers 158R, 158G, and 158B is reduced. The respective sacrificial layers 158R, 158G, and 158B thus remain above the organic interconnect layers 103R, 103G, and 103B, and damage to the organic interconnect layers 103R, 103G, and 103B can be prevented by treatment in a later step.

[0385] Subsequently, exposure is preferably performed on the entire substrate such that the insulating layer 127a is irradiated with visible light or ultraviolet rays. The energy density for exposure is preferably higher than 0 mJ / cm 2 and less than or equal to 800 mJ / cm 2 , preferably higher than 0 mJ / cm 2 and less than or equal to 500 mJ / cm 2Performing such exposure after development can, in some cases, increase the degree of transparency of the insulating layer 127a. Furthermore, in some cases, it is possible to lower the substrate temperature required for the subsequent heat treatment to change the shape of the insulating layer 127a into a tapered shape.

[0386] Here, if an insulating barrier layer against oxygen (e.g., an aluminum oxide film) is provided as each of the sacrificial layers 158R, 158G, and 158B, diffusion of oxygen into the organic compound layers 103R, 103G, and 103B can be prevented.

[0387] Then, a heat treatment (also called post-baking) is performed. The heat treatment can change the insulating layer 127a into the insulating layer 127 with a tapered side surface ( Fig.8C). The heat treatment is performed at a temperature lower than the upper temperature limit of the organic compound layer. The heat treatment can be performed at a substrate temperature of higher than or equal to 50°C and lower than or equal to 200°C, preferably higher than or equal to 60°C and lower than or equal to 150°C, more preferably higher than or equal to 70°C and lower than or equal to 130°C. The heating atmosphere can be an air atmosphere or an inert gas atmosphere. Furthermore, the heating atmosphere can be an atmospheric pressure atmosphere or a reduced pressure atmosphere. Accordingly, the adhesion between the insulating layer 127 and the inorganic insulating layer 125 can be improved, and the corrosion resistance of the insulating layer 127 can be increased.

[0388] If the sacrificial layers 158R, 158G, and 158B are not completely removed by the first etching treatment and the thin sacrificial layers 158R, 158G, and 158B remain, the organic interconnect layers 103R, 103G, and 103B can be prevented from being damaged and deteriorated during the heat treatment. This increases the reliability of the light-emitting device.

[0389] Next, as in Fig. 9A, an etching treatment is performed using the insulating layer 127 as a mask to remove a portion of the sacrificial layers 158R, 158G, and 158B. Thus, openings are formed in the sacrificial layers 158R, 158G, and 158B, and the upper surfaces of the organic interconnection layers 103R, 103G, and 103B and the conductive layer 152C are exposed. Note that this etching treatment may be referred to as a second etching treatment hereinafter.

[0390] An end portion of the inorganic insulating layer 125 is covered with the insulating layer 127. Fig. 9A illustrates an example in which a part of an end portion of the sacrificial layer 158G (specifically, a tapered portion formed by the first etching treatment) is covered with the insulating layer 127, and a tapered portion formed by the second etching treatment is exposed.

[0391] The second etching treatment is performed by wet etching. Using a wet etching process can reduce damage to the organic compound layers 103R, 103G, and 103B compared to using a dry etching process. Wet etching can be performed using, for example, an alkaline solution or an acidic solution. An aqueous solution is preferably used to prevent the organic compound layer 103 from dissolving.

[0392] Then, as in Fig. 9B, a common electrode 155 is formed over the organic interconnect layers 103R, 103G, and 103B, the conductive layer 152C, and the insulating layer 127. The common electrode 155 may be formed by a sputtering method, a vacuum evaporation method, or the like. In this case, as shown in Fig. 3B, a multilayer structure of the first EL layer 104 and the second EL layer 105 may be used as the organic interconnection layer 103, and the common electrode 155 may be formed thereover.

[0393] Next, as in Fig. As shown in Figure 9C, the protective layer 131 is formed over the common electrode 155. The protective layer 131 can be formed by a vacuum evaporation method, a sputtering method, a CVD method, an ALD method, or the like.

[0394] Then, the substrate 120 is bonded to the protective layer 131 using the resin layer 122, so that the display device can be manufactured. As described above, in the method for manufacturing the display device of one embodiment of the present invention, the insulating layer 156 is formed to include a region overlapping the side surface of the conductive layer 151, and the conductive layer 152 is formed to cover the conductive layer 151 and the insulating layer 156. This can increase the yield of the display device and prevent the generation of defects.

[0395] As described above, in the method for manufacturing the display device of one embodiment of the present invention, the island-shaped organic compound layers 103R, 103G, and 103B are formed not by using a fine metal mask, but by processing a film formed on the entire surface. Thus, the island-shaped layers can be formed to have a uniform thickness. Consequently, a high-resolution display device or a high-aperture display device can be obtained. Furthermore, even when the resolution or aperture ratio is high and the distance between the subpixels is very short, the organic compound layers 103R, 103G, and 103B in the adjacent subpixels can be prevented from being in contact with each other. As a result, the generation of the leakage current between the subpixels can be prevented.This can prevent crosstalk so that a very high contrast display can be obtained.

[0396] Furthermore, even a display device comprising tandem light-emitting devices formed by a photolithography technique can have high moisture resistance, high water resistance, high oxygen resistance, high chemical resistance, low operating voltage, and high emission efficiency. (Embodiment 4)

[0397] In this embodiment, a display device of an embodiment of the present invention will be described.

[0398] The display device in this embodiment may be a high-resolution display device. Therefore, the display device in this embodiment can be used for display sections of information terminals (wearable devices), such as wristwatch-type and bracelet-type information terminals, and display sections of head-mounted wearable devices, such as a VR device such as a head-mounted display (HMD) and a glasses-type AR device.

[0399] The display device in this embodiment may be a high-definition display device or a large-size display device. Accordingly, the display device in this embodiment can be used for display sections of a digital camera, a digital video camera, a digital photo frame, a mobile phone, a portable game console, a portable information terminal, and an audio playback device, in addition to display sections of electronic devices with a relatively large screen, such as a television, desktop and laptop PCs, a computer monitor, and the like, a digital signage device, and a large-size gaming machine such as a pachinko machine. [Display module]

[0400] Fig.10A is a perspective view of a display module 280. The display module 280 includes a display device 100A and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100A and may be any of the display devices 100B to 100E described below.

[0401] The display module 280 includes a substrate 291 and a substrate 292. The display module 280 includes a display section 281. The display section 281 is a region of the display module 280 in which an image is displayed, and is a region in which light emitted from pixels provided in a pixel section 284 described below can be seen.

[0402] Fig.10B is a perspective view schematically illustrating the structure on the side of the substrate 291. A circuit portion 282, a pixel circuit portion 283, and the pixel portion 284 are stacked above the substrate 291. Furthermore, a terminal portion 285 for connecting to the FPC 290 is included in a portion above the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected to each other via a wiring portion 286 formed from a plurality of wires.

[0403] The pixel section 284 includes a plurality of periodically arranged pixels 284a. An enlarged view of a pixel 284a is shown on the right side in Fig.10B. Pixels 284a may employ any of the structures described in the preceding embodiments. Fig. Figure 10B illustrates an example in which pixel 284a has a structure similar to that of the pixel shown in Fig. 3A is similar to pixel 178.

[0404] The pixel circuit section 283 includes a plurality of periodically arranged pixel circuits 283a.

[0405] A pixel circuit 283a is a circuit that controls the operation of a plurality of elements included in a pixel 284a.

[0406] The circuit section 282 includes a circuit for driving the pixel circuits 283a in the pixel circuit section 283. For example, the circuit section 282 preferably includes a gate line driver circuit and / or a source line driver circuit. The circuit section 282 may also include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0407] The FPC 290 serves as a line for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may be mounted on the FPC 290.

[0408] The display module 280 may have a structure in which the pixel circuit portion 283 and / or the circuit portion 282 are arranged below the pixel portion 284; therefore, the aperture ratio (the effective display area ratio) of the display portion 281 can be significantly high.

[0409] Such a display module 280 has a very high resolution and can therefore be suitably used for a VR device such as an HMD or a glasses-type AR device. For example, even in the case of a structure in which the display portion of the display module 280 is viewed through a lens, pixels of the very high resolution display portion 281 included in the display module 280 are prevented from being recognized when the display portion is magnified by the lens, so that display providing a high sense of immersion can be performed. Without being limited to this, the display module 280 can be suitably used for electronic devices including a relatively small display portion. [Display device 100A]

[0410] The Fig.The display device 100A shown in Figure 11A includes a substrate 301, the light-emitting devices 130R, 130G, and 130B, a capacitor 240, and a transistor 310.

[0411] The substrate 301 corresponds to the substrate 291 in Fig. 10A and Fig.10B. The transistor 310 includes a channel formation region in the substrate 301. For the substrate 301, for example, a semiconductor substrate such as a single-crystal silicon substrate can be used. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 serves as a gate electrode. The insulating layer 313 is positioned between the substrate 301 and the conductive layer 311 and serves as a gate insulating layer. The low-resistance region 312 is a region where the substrate 301 is doped with an impurity and serves as a source or drain. The insulating layer 314 is provided so as to cover the side surface of the conductive layer 311.

[0412] An element isolation layer 315 is provided between two adjacent transistors 310 such that it is embedded in the substrate 301.

[0413] An insulating layer 261 is provided to cover the transistor 310, and the capacitor 240 is provided over the insulating layer 261.

[0414] The capacitor 240 includes a conductive layer 241, a conductive layer 245, and an insulating layer 243 between the conductive layers 241 and 245. The conductive layer 241 serves as one electrode of the capacitor 240, the conductive layer 245 serves as the other electrode of the capacitor 240, and the insulating layer 243 serves as the dielectric of the capacitor 240.

[0415] The conductive layer 241 is provided over the insulating layer 261 and is embedded in an insulating layer 254. The conductive layer 241 is electrically connected to a source and drain terminal of the transistor 310 via a terminal plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping the conductive layer 241, with the insulating layer 243 interposed therebetween.

[0416] An insulating layer 255 is provided to cover the capacitor 240. The insulating layer 174 is provided over the insulating layer 255. The insulating layer 175 is provided over the insulating layer 174. The light-emitting devices 130R, 130G, and 130B are provided over the insulating layer 175. An insulator is provided in regions between adjacent light-emitting devices.

[0417] The insulating layer 156R is formed to include a region overlapping the side surface of the conductive layer 151R. The insulating layer 156G is provided to include a region overlapping the side surface of the conductive layer 151G. The insulating layer 156B is provided to include a region overlapping the side surface of the conductive layer 151B. The conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R. The conductive layer 152G is provided to cover the conductive layer 151G and the insulating layer 156G. The conductive layer 152B is provided to cover the conductive layer 151B and the insulating layer 156B. The sacrificial layer 158R is positioned over the organic interconnect layer 103R. The sacrificial layer 158G is positioned above the organic interconnect layer 103G.The sacrificial layer 158B is positioned over the organic interconnect layer 103B.

[0418] The conductive layers 151R, 151G, and 151B are each electrically connected to a source and drain terminal of the corresponding transistor 310 via a terminal plug 256 embedded in the insulating layers 243, 255, 174, and 175, the conductive layer 241 embedded in the insulating layer 254, and the terminal plug 271 embedded in the insulating layer 261. Any of various conductive materials can be used for the terminal plugs.

[0419] The protective layer 131 is provided over the light-emitting devices 130R, 130G, and 130B. The substrate 120 is bonded to the protective layer 131 with the resin layer 122. Reference can be made to Embodiment 3 for the details of the light-emitting device 130 and the components thereabove up to the substrate 120. The substrate 120 corresponds to the substrate 292 in Fig. 10A.

[0420] Fig. 11B shows a variation example of the Fig. 11A. The display device 100A shown in Fig. 11B comprises a color layer 132R, a color layer 132G, and a color layer 132B, and each of the light-emitting devices 130 includes an area overlapping with one of the color layers 132R, 132G, and 132B. In the Fig.In the display device shown in Figure 11B, the light-emitting device 130 can emit white light, for example. The color layer 132R, the color layer 132G, and the color layer 132B can transmit red light, green light, and blue light, for example, respectively. [Display device 100B]

[0421] Fig. 12 is a perspective view of the display device 100B.

[0422] In the display device 100B, a substrate 352 and a substrate 351 are bonded together. In Fig. 12, the substrate 352 is represented by a dashed line.

[0423] The display device 100B includes the pixel portion 177, the connection portion 140, a circuit 356, a wiring 355, and the like. Fig. 12 shows an example in which an IC 354 and an FPC 353 are mounted on the display device 100B. Therefore, the Fig.The structure shown in Figure 12 can be regarded as a display module including the display device 100B, the integrated circuit (IC), and the FPC. Here, a display device in which a substrate is provided with a terminal such as an FPC or is mounted with an IC is referred to as a display module.

[0424] The connecting portion 140 is provided outside the pixel portion 177. The number of connecting portions 140 may be one or more. In the connecting portion 140, a common electrode of a light-emitting device is electrically connected to a conductive layer so that a potential can be supplied to the common electrode.

[0425] For example, a scan line driver circuit can be used as circuit 356.

[0426] The line 355 has a function of supplying a signal and a current to the pixel section 177 and the circuit 356. The signal and current are input to the line 355 from the outside via the FPC 353 or from the IC 354.

[0427] Fig. 12 illustrates an example in which the IC 354 is provided over the substrate 351 by a chip-on-glass (COG) method, a chip-on-film (COF) method, or the like. For example, an IC including a scan line driver circuit, a signal line driver circuit, or the like can be used as the IC 354. Note that the display device 100B and the display module are not necessarily provided with an IC. Alternatively, the IC may be mounted on the FPC by, for example, a COF method.

[0428] Fig.13 illustrates an example of the cross sections of a part of an area including the FPC 353, a part of the circuit 356, a part of the pixel portion 177, a part of the connection portion 140, and a part of an area including an end portion of the display device 100B. [Display device 100C]

[0429] The Fig. The display device 100C shown in Fig. 13 includes a transistor 201, a transistor 205, the light-emitting device 130R that emits red light, the light-emitting device 130G that emits green light, the light-emitting device 130B that emits blue light, and the like between the substrate 351 and the substrate 352.

[0430] For the details of the light-emitting devices 130R, 130G and 130B, reference may be made to Embodiments 1 to 3.

[0431] Light-emitting device 130R includes conductive layer 224R, conductive layer 151R over conductive layer 224R, and conductive layer 152R over conductive layer 151R. Light-emitting device 130G includes conductive layer 224G, conductive layer 151G over conductive layer 224G, and conductive layer 152G over conductive layer 151G. Light-emitting device 130B includes conductive layer 224B, conductive layer 151B over conductive layer 224B, and conductive layer 152B over conductive layer 151B.

[0432] The conductive layer 224R is connected to a conductive layer 222b included in the transistor 205 via an opening provided in an insulating layer 214. An end portion of the conductive layer 151R is positioned further outside an end portion of the conductive layer 224R. The insulating layer 156R is provided to include a region in contact with the side surface of the conductive layer 151R, and the conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R.

[0433] The conductive layers 224G, 151G, and 152G and the insulating layer 156G in the light-emitting device 130G will not be described in detail because they are similar to the conductive layers 224R, 151R, and 152R and the insulating layer 156R in the light-emitting device 130R, respectively; the same applies to the conductive layers 224B, 151B, and 152B and the insulating layer 156B in the light-emitting device 130B.

[0434] The conductive layers 224R, 224G, and 224B each have a recessed portion covering the opening provided in the insulating layer 214. A layer 128 is embedded in the recessed portion.

[0435] Layer 128 has a function of filling the recessed portions of conductive layers 224R, 224G, and 224B to maintain planarity. Conductive layers 151R, 151G, and 151B are provided above conductive layers 224R, 224G, and 224B and layer 128, and are electrically connected to conductive layers 224R, 224G, and 224B, respectively. Therefore, the regions overlapping the recessed portions of conductive layers 224R, 224G, and 224B can also be used as light-emitting regions, thereby increasing the pixel aperture ratio.

[0436] Layer 128 may be an insulating layer or a conductive layer. Any of various inorganic insulating materials, organic insulating materials, and conductive materials may be appropriately used for layer 128. Specifically, layer 128 is preferably formed using an insulating material, and particularly preferably, an organic insulating material. For example, layer 128 may be formed using an organic insulating material suitable for insulating layer 127.

[0437] The protective layer 131 is provided over the light-emitting devices 130R, 130G, and 130B. The protective layer 131 and the substrate 352 are bonded together with an adhesive layer 142. The substrate 352 is provided with an opaque layer 157. A solid sealing structure, a hollow sealing structure, or the like can be used to seal the light-emitting device 130. Fig.13, a solid sealing structure is used in which a space between the substrate 352 and the substrate 351 is filled with the adhesive layer 142. Alternatively, the space may be filled with an inert gas (e.g., nitrogen or argon), meaning that a hollow sealing structure may be used. In this case, the adhesive layer 142 may be provided such that it does not overlap with the light-emitting device. Alternatively, the space may be filled with a resin other than the frame-like adhesive layer 142.

[0438] Fig.13 illustrates an example in which the connecting portion 140 includes a conductive layer 224C obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, the conductive layer 151C obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and the conductive layer 152C obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. In the example shown in Fig. In the example shown in Fig. 13, the insulating layer 156C is provided to include a region overlapping with the side surface of the conductive layer 151C.

[0439] The display device 100B has a top-emission structure. Light from the light-emitting device is emitted toward the substrate 352. For the substrate 352, a material having high transmittance to visible light is preferably used. In the case where the light-emitting element emits infrared or near-infrared light, a material having high transmittance to infrared or near-infrared light is preferably used. The pixel electrode includes a material that reflects visible light, and the counter electrode (the common electrode 155) includes a material that transmits visible light.

[0440] Above the substrate 351, an insulating layer 211, an insulating layer 213, an insulating layer 215, and the insulating layer 214 are provided in this order. A part of the insulating layer 211 serves as the gate insulating layer of each transistor. A part of the insulating layer 213 serves as the gate insulating layer of each transistor. The insulating layer 215 is provided to cover the transistors. The insulating layer 214 is provided to cover the transistors and has a function of a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and they may each be one or more.

[0441] An inorganic insulating film is preferably used as each of the insulating layers 211, 213 and 215.

[0442] An organic insulating layer is suitable for the insulating layer 214, which serves as a planarization layer.

[0443] The transistors 201 and 205 each include a conductive layer 221 serving as a gate, the insulating layer 211 serving as a gate insulating layer, a conductive layer 222a and the conductive layer 222b serving as a source and drain, a semiconductor layer 231, the insulating layer 213 serving as a gate insulating layer, and a conductive layer 223 serving as a gate.

[0444] A connecting portion 204 is provided in a region of the substrate 351 that does not overlap with the substrate 352. In the connecting portion 204, the source electrode or the drain electrode of the transistor 201 is electrically connected to the FPC 353 via a conductive layer 166 and an interconnection layer 242. For example, the conductive layer 166 has a multi-layer structure composed of a conductive film obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive film obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive film obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. The conductive layer 166 is exposed on top of the connecting portion 204.Therefore, the connecting portion 204 and the FPC 353 can be electrically connected to each other via the connecting layer 242.

[0445] The opaque layer 157 is preferably provided on the surface of the substrate 352 on the side of the substrate 351. The opaque layer 157 can be provided over an area between adjacent light-emitting devices, in the connecting portion 140, in the circuit 356, and the like. Various optical components can be arranged on the outside of the substrate 352.

[0446] A material that can be used for the substrate 120 can be used for each of the substrates 351 and 352.

[0447] A material that can be used for the resin layer 122 can be used for the adhesive layer 142.

[0448] As the connecting layer 242, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like can be used. [Display device 100D]

[0449] The Fig. The display device 100D shown in Figure 14 differs from the display device 100C in Fig. 13 mainly because it has a bottom-emission structure.

[0450] Light from the light-emitting device is emitted toward the substrate 351. A material having high visible light transmittance is preferably used for the substrate 351. In contrast, there is no limitation on the light transmittance of a material used for the substrate 352.

[0451] The opaque layer is preferably formed between the substrate 351 and the transistor 201 and between the substrate 351 and the transistor 205. Fig. 14 illustrates an example in which the opaque layer 157 is provided over the substrate 351, an insulating layer 153 is provided over the opaque layer 157, and the transistors 201 and 205 and the like are provided over the insulating layer 153.

[0452] The light-emitting device 130R includes a conductive layer 112R, a conductive layer 126R over the conductive layer 112R, and a conductive layer 129R over the conductive layer 126R.

[0453] The light-emitting device 130B includes a conductive layer 112B, a conductive layer 126B over the conductive layer 112B, and a conductive layer 129B over the conductive layer 126B.

[0454] A material with high visible light transmittance is used for each of the conductive layers 112R, 112B, 126R, 126B, 129R, and 129B. A material that reflects visible light is preferably used for the common electrode 155.

[0455] Although in Fig. 14, the light-emitting device 130G is also provided.

[0456] Although Fig. 14 and the like illustrate an example in which the top surface of the layer 128 includes a flat portion, the shape of the layer 128 is not particularly limited. [Display device 100E]

[0457] The Fig. The display device 100E shown in Figure 15 is a variation example of the Fig. 13 and differs from the display device 100C mainly in that it includes the color layers 132R, 132G and 132B.

[0458] In the display device 100E, the light-emitting device 130 includes a region overlapping with one of the color layers 132R, 132G, and 132B. The color layers 132R, 132G, and 132B may be provided on a surface of the substrate 352 on the side of the substrate 351. End portions of the color layers 132R, 132G, and 132B may overlap with the opaque layer 157.

[0459] In the display device 100E, the light-emitting device 130 can emit white light, for example. The color layer 132R, the color layer 132G, and the color layer 132B can transmit red light, green light, and blue light, for example, respectively. Note that in the display device 100E, the color layers 132R, 132G, and 132B can be provided between the protective layer 131 and the adhesive layer 142.

[0460] Although Fig. 13 and Fig.15 and the like illustrate an example in which the top surface of the layer 128 includes a flat portion, the shape of the layer 128 is not particularly limited.

[0461] This embodiment can be appropriately combined with other embodiments or examples. Where a plurality of structural examples are shown in one embodiment in this specification, the structural examples can be combined as needed. (Embodiment 5)

[0462] In this embodiment, electronic devices of an embodiment of the present invention will be described.

[0463] Electronic devices of this embodiment incorporate the display device of one embodiment of the present invention in their display sections. The display device of one embodiment of the present invention has high display performance, and its resolution and image sharpness can be easily increased. Therefore, the display device of one embodiment of the present invention can be used for display sections of various electronic devices.

[0464] Examples of the electronic devices include a digital camera, a digital video camera, a digital photo frame, a mobile phone, a portable game console, a portable information terminal, and an audio playback device, in addition to electronic devices having a relatively large screen such as a television, desktop or laptop PCs, a monitor of a computer, and the like, a digital signage, and a large gaming machine such as a pachinko machine.

[0465] In particular, the display device of one embodiment of the present invention can have a high resolution and can therefore be advantageously used for an electronic device with a relatively small display section. Examples of such an electronic device include information terminals in the form of a wristwatch and a bracelet (wearable devices), and wearable devices that can be worn on the head, such as a VR device, a head-mounted display, a glasses-type AR device, and an MR device.

[0466] The electronic device in this embodiment may include a sensor (a sensor having a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, a chemical substance, sound, time, hardness, electric field, current, voltage, electric power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0467] Based on Fig. 16A to Fig. 16D describes examples of wearable devices that can be worn on the head.

[0468] One in Fig. 16A and an electronic device 700A shown in Fig.16B each include a pair of display panels 751, a pair of housings 721, a communication section (not shown), a pair of fixing sections 723, a control section (not shown), an imaging section (not shown), a pair of optical components 753, a frame 757, and a pair of nose pads 758.

[0469] The display device of one embodiment of the present invention can be used in the display panels 751. Therefore, the electronic devices can be highly reliable.

[0470] The electronic devices 700A and 700B can each project images displayed on the display panels 751 onto display areas 756 of the optical components 753. Since the optical components 753 have a light transmission property, the user can see images displayed on the display areas superimposed on transmission images viewed through the optical components 753.

[0471] In the electronic devices 700A and 700B, a camera capable of capturing images on the front side may be provided as an imaging section. Furthermore, if the electronic devices 700A and 700B are provided with an acceleration sensor such as a gyroscope sensor, the orientation of the user's head can be detected, and an image corresponding to the orientation can be displayed on the display areas 756.

[0472] The communication section includes a wireless communication device, and, for example, a video signal can be supplied from the wireless communication device. Instead of the wireless communication device or in addition thereto, a connecting element can be provided, which can be connected to a cable for supplying a video signal and a power supply potential.

[0473] The 700A and 700B electronic devices are equipped with a battery so that they can be charged wirelessly and / or wired.

[0474] A touch sensor module may be provided in the housing 721.

[0475] Various touch sensors can be applied to the touch sensor module. For example, one of the following types of touch sensors can be used: a capacitive type, a resistive type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, and an optical type. In particular, a capacitive sensor or an optical sensor is preferably used for the touch sensor module.

[0476] One in Fig. 16C shown electronic device 800A and a Fig. 16D each include a pair of display sections 820, a housing 821, a communication section 822, a pair of mounting sections 823, a control section 824, a pair of imaging sections 825, and a pair of lenses 832.

[0477] The display device of one embodiment of the present invention can be used in the display sections 820. Therefore, the electronic devices can be highly reliable.

[0478] The display sections 820 are located within the housing 821 such that they are viewed through the lenses 832. When the pair of display sections 820 display different images, a three-dimensional display can be performed using parallax.

[0479] The electronic devices 800A and 800B preferably include a mechanism for adjusting the lateral positions of the lenses 832 and the display sections 820 so that the lenses 832 and the display sections 820 are optimally positioned depending on the positions of the user's eyes.

[0480] The electronic device 800A or the electronic device 800B can be attached to the user's head with the attachment portions 823.

[0481] The imaging section 825 has a function for obtaining information about the external environment. Data obtained by the imaging section 825 can be output to the display section 820. An image sensor can be used for the imaging section 825. Furthermore, a plurality of cameras can be provided to include a variety of fields of view, such as a telescopic field of view and a wide-angle field of view.

[0482] The electronic device 800A may include a vibration mechanism that serves as a bone conduction earphone.

[0483] Electronic devices 800A and 800B may each include an input terminal. A cable for supplying a video signal from a video output device or the like, power for charging a battery provided in the electronic device, and the like may be connected to the input terminal.

[0484] The electronic device of one embodiment of the present invention may have a function for performing wireless communication with earphones 750.

[0485] The electronic device may include an earphone portion. The electronic device 700B in Fig. 16B includes earphone portions 727. A portion of a line connecting the earphone portion 727 and the control portion may be located within the housing 721 or the mounting portion 723.

[0486] Similarly, the electronic device 800B in Fig. 16D earphone sections 827. For example, the earphone section 827 may be connected to the control section 824 via a line.

[0487] As described above, both the eyeglass-like device (e.g., electronic devices 700A and 700B) and the goggle-like device (e.g., electronic devices 800A and 800B) are preferable as the electronic device of one embodiment of the present invention.

[0488] One in Fig. Electronic device 6500 shown in Figure 17A is a portable information terminal that can be used as a smartphone.

[0489] The electronic device 6500 includes a housing 6501, a display section 6502, a power button 6503, buttons 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, and the like. The display section 6502 has a touchscreen function.

[0490] The display device of one embodiment of the present invention can be used in the display section 6502. Therefore, the electronic device can be highly reliable.

[0491] Fig. 17B is a schematic cross-sectional view including an end portion of the housing 6501 on the side of the microphone 6506.

[0492] A protective part 6510 having a light transmittance property is provided on the display surface side of the housing 6501. A display panel 6511, an optical component 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, and the like are provided in a space surrounded by the housing 6501 and the protective part 6510.

[0493] The display panel 6511, the optical component 6512 and the touch sensor panel 6513 are attached to the protective part 6510 with an adhesive layer (not shown).

[0494] A portion of the display panel 6511 is folded back in an area outside the display section 6502, and an FPC 6515 is connected to the folded back portion. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on the printed circuit board 6517.

[0495] The display device of one embodiment of the present invention can be used in the display panel 6511. Therefore, the electronic device can be very lightweight. Since the display panel 6511 is very thin, the high-capacity battery 6518 can be mounted without increasing the thickness of the electronic device. Furthermore, a part of the display panel 6511 is folded back to provide a connection portion with the FPC 6515 on the back of the pixel portion, allowing the electronic device to have a narrow frame.

[0496] Fig.17C illustrates an example of a television set. In a television set 7100, a display section 7000 is installed in a housing 7171. Here, the housing 7171 is supported by a base 7173.

[0497] The display device of one embodiment of the present invention can be used in the display section 7000. Therefore, the electronic device can be highly reliable.

[0498] An operation of the Fig. 17C can be performed with an operating switch provided in the housing 7171 and a separate remote control 7151.

[0499] Fig. 17D illustrates an example of a laptop PC. A laptop PC 7200 includes a case 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. The display section 7000 is installed in the case 7211.

[0500] The display device of one embodiment of the present invention can be used in the display section 7000. Therefore, the electronic device can be highly reliable.

[0501] Fig. 17E and Fig. 17F show examples of digital signage.

[0502] One in Fig. The digital signage 7300 shown in Figure 17E includes a housing 7301, the display section 7000, a speaker 7303, and the like. The digital signage 7300 may also include an LED lamp, operation buttons (including a power button or an operation switch), a connection port, various sensors, a microphone, and the like.

[0503] Fig. 17F shows a digital signage 7400 mounted on a cylindrical column 7401. The digital signage 7400 includes the display portion 7000 provided along a curved surface of the column 7401.

[0504] In Fig. 17E and Fig. 17F, the display device of one embodiment of the present invention can be used in the display section 7000. Therefore, the electronic devices can be highly reliable.

[0505] A larger area of ​​the display section 7000 can increase the amount of information that can be provided at once. The display section 7000 with a larger area attracts more attention, so, for example, the effectiveness of advertising can be increased.

[0506] As in Fig. 17E and Fig. 17F, it is preferred that the digital signage 7300 or the digital signage 7400 can interact with an information terminal 7311 or an information terminal 7411, such as a smartphone, possessed by a user through wireless communication.

[0507] The Fig. 18A to Fig.18G each include a housing 9000, a display section 9001, a speaker 9003, an operation button 9005 (including a power button or an operation switch), a connection terminal 9006, a sensor 9007 (a sensor having a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electric energy, radiation, flow rate, humidity, gradient, oscillation, odor, or infrared rays), a microphone 9008, and the like.

[0508] The Fig. 18A to Fig.The electronic devices illustrated in Figure 18G have various functions. For example, the electronic devices may have a function for displaying various information (e.g., a still image, a moving image, and a text image) on the display section, a touchscreen function, a function for displaying a calendar, the date, time, and the like, a processing control function using various types of software (programs), a wireless communication function, and a function for reading and processing a program or data stored in a storage medium.

[0509] Below are the electronic devices in Fig. 18A to Fig. 18G described in detail.

[0510] Fig.18A is a perspective view of a portable information terminal 9171. For example, the portable information terminal 9171 can be used as a smartphone. The portable information terminal 9171 can include the speaker 9003, the connection port 9006, the sensor 9007, or the like. The portable information terminal 9171 can display text and image information on its plurality of surfaces. Fig.18A illustrates an example in which three icons 9050 are displayed. In addition, information 9051 represented by dashed rectangles may be displayed on another surface of the display section 9001. Examples of the information 9051 include a notification of the arrival of an email, an SNS message, an incoming call, or the like; the subject and sender of an email, an SNS message, or the like; the date, time, remaining battery power, and the intensity of a radio wave. Alternatively, the icon 9050 or the like may be displayed at the location where the information 9051 is displayed.

[0511] Fig.18B is a perspective view of a portable information terminal 9172. The portable information terminal 9172 has a function of displaying information on three or more surfaces of the display section 9001. Here, information 9052, information 9053, and information 9054 are displayed on the respective surfaces. For example, the user of the portable information terminal 9172 can check the information 9053 displayed in a manner that can be viewed from above the portable information terminal 9172, with the portable information terminal 9172 stored in a breast pocket of their clothing.

[0512] Fig.18C is a perspective view of a tablet terminal 9173. The tablet terminal 9173 is suitable for executing various applications, such as mobile phone calls, sending and receiving emails, viewing and editing texts, playing music, Internet communication, and playing computer games. The tablet terminal 9173 includes the display section 9001, the camera 9002, the microphone 9008, and the speaker 9003 on the front of the housing 9000, the operation buttons 9005 as buttons for operation on the left side of the housing 9000, and the connection port 9006 on the bottom of the housing 9000.

[0513] Fig.18D is a perspective view of a portable information terminal 9200 in the form of a wristwatch. The portable information terminal 9200 can be used, for example, as a smartwatch (registered trademark). The display surface of the display section 9001 is curved, and an image can be displayed on the curved display surface. Furthermore, for example, mutual communication can be performed between the portable information terminal 9200 and a headset capable of wireless communication, and therefore, hands-free phone calls are possible. The portable information terminal 9200 can perform mutual data transmission with another information terminal and charging using the connection port 9006. Note that charging can be performed by wireless power supply.

[0514] Fig. 18E to Fig.18G are perspective views of a foldable portable information terminal 9201. Fig. 18E is a perspective view illustrating the portable information terminal 9201 being unfolded. Fig. 18G is a perspective view illustrating the portable information terminal 9201 being folded. Fig. Fig. 18F is a perspective view illustrating the portable information terminal 9201 being changed from one of the states in Fig. 18E and Fig.18G is transferred to the other. The portable information terminal 9201 is highly portable when folded. When the portable information terminal 9201 is unfolded, a seamless large display area is highly searchable. The display section 9001 of the portable information terminal 9201 is supported by three housings 9000 connected to each other by hinges 9055. For example, the display section 9001 can be folded with a radius of curvature greater than or equal to 0.1 mm and less than or equal to 150 mm.

[0515] This embodiment can be appropriately combined with other embodiments or examples. Where a plurality of structural examples are shown in one embodiment in this specification, the structural examples can be combined as needed. [Example 1]

[0516] This example describes the detailed fabrication processes and properties of light-emitting devices 1-1 to 1-8, which are tandem light-emitting devices using organic electron-transport compounds (second organic compounds) with different LUMO levels for the first and second layers of the interlayers. Structural formulas of the main compounds used in this example are shown below.

[0530] (Manufacturing method of the light-emitting device 1-1)

[0517] First, 100 nm thick silver (Ag) and 85 nm thick indium tin oxide containing silicon oxide (ITSO) were sequentially deposited as a reflective electrode and a transparent electrode, respectively, on a glass substrate from the substrate side by a sputtering method, thereby forming the first electrode 101 with a size of 2 mm × 2 mm. Note that the transparent electrode serves as the anode, and the transparent electrode and the reflective electrode are collectively considered the first electrode 101.

[0518] Next, in a pretreatment for forming the light-emitting device over a substrate, the surface of the substrate was washed with water, and baking was performed at 200 °C for one hour.

[0519] The substrate was then transferred to a vacuum evaporation device where the pressure was increased to approximately 1 × 10 -4Pa, and was subjected to vacuum baking for 30 minutes at 170 °C in a heating chamber of the vacuum evaporation device, and then the substrate was cooled for approximately 30 minutes.

[0520] The substrate provided with the first electrode 101 was then attached to a holder in the vacuum evaporation device such that the surface on which the first electrode 101 was formed faced downward. Over the first electrode 101, N-(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 with a molecular weight of 672 (OCHD-003) were co-evaporated to a thickness of 10 nm such that the weight ratio of PCBBiF to OCHD-003 was 1:0.03, thereby forming the hole-injection layer 111.

[0521] PCBBiF was deposited by evaporation over the hole injection layer 111 to a thickness of 90 nm, forming a first hole transport layer.

[0522] Then, 8-(p-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm), represented by the above structural formula (ii), 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP), represented by the above structural formula (iii), and [2-d3-methyl-8-(2-pyridinyl-ĸN)benzofuro[2,3-b]pyridine-ĸC]bis[2-(5-d3-methyl-2-pyridinyl-ĸN2)phenyl-ĸC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)) represented by the above structural formula (iv) was deposited by co-evaporation to a thickness of 40 nm such that the weight ratio of 8mpTP-4mDBtPBfpm to βNCCP and Ir(5mppy-d3)2(mbfpypy-d3) was 0.5:0.5:0.1, thereby forming a first light-emitting layer.

[0523] Next, 3,6-bis(diphenylamino)-9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9H-carbazole (abbreviation: DACT-II), represented by the above structural formula (v), was deposited by evaporation to a thickness of 10 nm to form a first electron-transport layer.

[0524] After the first electron-transport layer was formed, 1,1'-pyridine-2,6-diyl-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) (abbreviation: hpp2py) as the second organic compound represented by the above structural formula (I) and 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviation: Pyrrd-Phen) as the first organic compound represented by the above structural formula (vi) were co-evaporated to a thickness of 5 nm such that the weight ratio of hpp2py to Pyrrd-Phen was 0.5:0.5, and then indium (In) was deposited by evaporation to a thickness of 2 nm to form a layer that will become the first region. Then, copper phthalocyanine (abbreviation: CuPc) represented by the above structural formula (vii) was deposited by evaporation to a thickness of 2 nm to form a layer which becomes the third region.Furthermore, PCBBiF and OCHD-003 were co-evaporated to a thickness of 10 nm in such a way that the weight ratio of PCBBiF to OCHD-003 was 1:0.15 to form a layer that would become the second region. Thus, an intermediate layer was formed.

[0525] PCBBiF was deposited by evaporation over the intermediate layer to a thickness of 55 nm, forming a second hole transport layer.

[0526] Over the second hole transport layer, 8mpTP-4mDBtPBfpm, βNCCP, and Ir(5mppy-d3)2(mbfpypy-d3) were co-evaporated to a thickness of 40 nm such that the weight ratio of 8mpTP-4mDBtPBfpm to βNCCP and Ir(5mppy-d3)2(mbfpypy-d3) was 0.5:0.5:0.1, thereby forming a second light-emitting layer.

[0527] Next, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) represented by the above structural formula (viii) was deposited by evaporation to a thickness of 20 nm, and then 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) represented by the above structural formula (ix) was deposited by evaporation to a thickness of 20 nm, thereby forming a second electron-transport layer.

[0528] A sample in which the second electron-transport layer and the components underneath were formed was exposed to an air atmosphere for one hour. The sample was then subjected to vacuum baking at 110 °C for one hour in a heating chamber of the vacuum evaporation device, where the pressure was maintained at approximately 1 × 10 -4 Pa was reduced.

[0529] Next, lithium fluoride (LiF) and ytterbium (Yb) were co-evaporated to a thickness of 1.5 nm such that the volume ratio of LiF to Yb was 1:0.5, and then silver (Ag) and magnesium (Mg) were co-evaporated to a thickness of 15 nm such that the volume ratio of Ag to Mg was 1:0.1, thereby forming the second electrode 102. Over the second electrode 102, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), represented by the above structural formula (x), was deposited to a thickness of 70 nm as a cap layer to improve the light extraction efficiency.

[0530] Then, the light-emitting device was sealed using a glass substrate in a glove box containing a nitrogen atmosphere so that the light-emitting device was not exposed to air. Specifically, a UV-curing sealing material was applied to enclose the device, only the sealing material was irradiated with UV light, while the light-emitting device was not irradiated with UV light, and a heat treatment was performed at 80°C under atmospheric pressure for one hour. Thus, the light-emitting device 1-1 was fabricated. (Manufacturing method of the light-emitting device 1-2)

[0531] The light-emitting device 1-2 was prepared in a similar manner to that for the light-emitting device 1-1, except that hpp2Py (the second organic compound) of the light-emitting device 1-1 was replaced with mPPhen2P represented by the above structural formula (II). (Manufacturing method of the light-emitting device 1-3)

[0532] The light-emitting device 1-3 was prepared in a similar manner to that for the light-emitting device 1-1, except that hpp2Py (the second organic compound) of the light-emitting device 1-1 was replaced with 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), which is represented by the above structural formula (III). (Manufacturing method of the light-emitting device 1-4)

[0533] The light-emitting device 1-4 was prepared in a similar manner to that for the light-emitting device 1-1, except that hpp2Py (the second organic compound) of the light-emitting device 1-1 was replaced with 2-{4-[9,10-di(2-naphthyl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviation: ZADN), which is represented by the above structural formula (IV). (Manufacturing method of the light-emitting device 1-5)

[0534] The light-emitting device 1-5 was prepared in a similar manner to that for the light-emitting device 1-1, except that hpp2Py (the second organic compound) of the light-emitting device 1-1 was replaced with 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviation: mSiTrz), which is represented by the above structural formula (V). (Manufacturing method of the light-emitting device 1-6)

[0535] The light-emitting device 1-6 was prepared in a similar manner to that for the light-emitting device 1-1, except that hpp2Py (the second organic compound) of the light-emitting device 1-1 was replaced with 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), which is represented by the above structural formula (VI). (Manufacturing method of the light-emitting device 1-7)

[0536] Light-emitting device 1-7 was manufactured in a similar manner to that for light-emitting device 1-1, except that hpp2Py (the second organic compound) of light-emitting device 1-1 was replaced with 8mpTP-4mDBtPBfpm represented by the above structural formula (VII). Note that in light-emitting device 1-7, the first light-emitting layer and the second light-emitting layer each contain an organic compound equal to the second organic compound (8mpTP-4mDBtPBfpm) of the intermediate layer. (Manufacturing method of the light-emitting device 1-8)

[0537] The light-emitting device 1-8 was prepared in a similar manner to that for the light-emitting device 1-1, except that hpp2Py (the second organic compound) of the light-emitting device 1-1 was replaced with 11-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 11mDBtBPPnfpr), which is represented by the above structural formula (VIII).

[0538] The device structures of the light-emitting devices 1-1 to 1-8 and the LUMO levels of the second organic compounds are described below. Thus, the light-emitting devices 1-1 to 1-8 are light-emitting devices each containing, in the first layer, the metal, the first organic compound having the first π-electron-deficient heteroaromatic ring with an electron-donor group, and the second organic compound having the second π-electron-deficient heteroaromatic ring.

[0539] It should be noted that the HOMO level and the LUMO level were obtained by cyclic voltammetry (CV) measurement.

[0540] In the cyclic voltammetry (CV) measurement, the values ​​(E) of HOMO and LUMO levels were determined based on an oxidation peak potential (E pa ) and a reduction peak potential (E pc) were calculated, which were obtained by changing the potential of a working electrode with respect to a reference electrode. During the measurement, the HOMO level and the LUMO level were obtained by scanning the potential in the positive direction and the negative direction, respectively. The scanning speed during the measurement was 0.1 V / s.

[0541] In particular, a standard oxidation-reduction potential (E o ) (= E pa + E pc ) / 2) from an oxidation peak potential (E pa ) and a reduction peak potential (E pc ) obtained from the cyclic voltammogram of a material. Then, the standard oxidation-reduction potential (E o ) of the potential energy (E x ) of the reference electrode with respect to a vacuum level, whereby each of the values ​​(E) (= E x - E o ) of HOMO and LUMO levels was obtained.

[0542] It should be noted that in the above case, the reversible oxidation-reduction wave was obtained. In the case where an irreversible oxidation-reduction wave is obtained, the HOMO level is calculated as follows: It is assumed that a value obtained by subtracting a predetermined value (0.1 eV) from an oxidation peak potential (E pa ) is obtained, a reduction peak potential (E pc ) and a standard oxidation-reduction potential (E o ) is calculated to one decimal place. To calculate the LUMO level, it was assumed that a value obtained by adding a predetermined value (0.1 eV) to a reduction peak potential (E pc ) is obtained, an oxidation peak potential (E pa ) and a standard oxidation-reduction potential (E o ) was calculated to one decimal place.

[0543] The glass transition temperatures (Tg) of the second organic compounds in the interlayers of the light-emitting devices 1-2 to 1-8 were measured using a differential scanning calorimeter (DSC); the Tg was 135 °C in mPPhen2P, 128 °C in αN-βNPAnth, 169 °C in ZADN, 108 °C in mSiTrz, 121 °C in mPn-mDMePyPTzn, 120 °C in 8mpTP-4mDBtPBfpm, and 130 °C in 11mDBtBPPnfpr, demonstrating their high thermal stability. [Table 5] Film thickness (nm) Cap layer 70 DBT3P-II second electrode 15 Ag: Mg (1:0.1) 1,5 LiF: Yb (2:1) Exposure to air second electron transport layer 2 20 mPPhen2P 1 20 2mPCCzPDBq second light-emitting layer 40 8mpTP-4mDBtPBfpm: βNCCP: Ir(5mppy-d3)2(mbfpypy-d3) (0.5:0.5:0.1) second hole transport layer 55 PCBBiF Intermediate layer second area 10 PCBBiF: OCHD-003 (1:0.15) third area 2 CuPc first area 2 In 5 *1: Pyridine-Phene (1:1) first electron transport layer 10 DACT-II first light-emitting layer 40 8mpTP-4mDBtPBfpm: βNCCP: Ir(5mppy-d3)2(mbfpypy-d3) (0.5:0.5:0.1) first hole transport layer 90 PCBBiF Hole injection layer 10 PCBBiF: OCHD-003 (1:0.03) first electrode transparent electrode 85 ITSO reflective electrode 100 Ag

[0559] [Table 6] *1 LUMO level (eV) Light-emitting device 1-1 hpp2Py -2,09 Light-emitting device 1-2 mPPhen2P -2,71 Light-emitting device 1-3 αN-βNPAnth -2,74 Light-emitting device 1-4 ZADN -2,87 Light-emitting device 1-5 mSiTrz -2,95 Light-emitting device 1-6 mPn-mDMePyPTzn -2,98 Light-emitting device 1-7 8mpTP-4mDBtPBfpm -3,01 Light-emitting device 1-8 11mDBtBPPnfpr -3,02

[0544] Fig. 22 shows the luminance-current density characteristics of the light-emitting devices 1-1 to 1-8, Fig. 23 shows the luminance-voltage characteristics of it, Fig. 24 shows the current efficiency-current density characteristics of it, Fig. 25 shows the current density-voltage characteristics of it and Fig.Figure 26 shows the electroluminescence spectra thereof. Table 7 shows the main characteristics of the light-emitting devices 1-1 to 1-8 at a luminance of approximately 1000 cd / m 2 The luminance, CIE chromaticity, and electroluminescence spectra were measured at normal temperature using a spectroradiometer (SR-UL1R, manufactured by TOPCON TECHNOHOUSE CORPORATION). [Table 7] Voltage (V) Current (mA) Current density (mA / cm 2 ) Chromaticity x Chromaticity y Power efficiency (cd / A) Light-emitting device 1-1 5,6 0,02 0,4 0,35 0,64 227,9 Light-emitting device 1-2 5,4 0,01 0,4 0,36 0,63 229,2 Light-emitting device 1-3 5,4 0,02 0,5 0,36 0,63 227,5 Light-emitting device 1-4 5,4 0,02 0,6 0,36 0,63 214,2 Light-emitting device 1-5 5,2 0,01 0,3 0,36 0,63 230,2 Light-emitting device 1-6 5,4 0,02 0,6 0,36 0,63 224,3 Light-emitting device 1-7 5,4 0,02 0,5 0,36 0,63 224,7 Light-emitting device 1-8 5,2 0,01 0,3 0,35 0,64 231,2

[0545] Fig. 22 to Fig. 26 and Table 6 show that the light-emitting devices 1-1 to 1-8 are all tandem light-emitting devices with advantageous current efficiency.

[0546] In addition, the Fig. The current density-voltage characteristics of the light-emitting devices 1-1 to 1-8 shown in Fig. 27 disclose that the light-emitting devices 1-1 to 1-8 have different operating voltages.

[0547] Fig.Figure 28 shows the relationship between voltages of the light-emitting devices 1-1 to 1-8 at a current density of 50 mA / cm 2 and the LUMO levels of the second organic compounds. Fig. 28, it is found that the operating voltage decreases significantly at the LUMO level of the second organic compound from lower than or equal to -2.75 eV, more significantly at lower than or equal to -2.80 eV, even more significantly at lower than or equal to -2.85 eV, even more significantly at lower than or equal to -2.90 eV, even more significantly at lower than or equal to -2.95 eV.

[0548] That is, this example discloses that, with reference to the LUMO level of the first organic compound of -2.55 eV for a lower operating voltage, the LUMO level of the second organic compound is preferably lower than that of the first organic compound by more than or equal to 0.20 eV, more preferably by more than or equal to 0.25 eV, even more preferably by more than or equal to 0.30 eV, even more preferably by more than or equal to 0.35 eV, even more preferably by more than or equal to 0.40 eV. [Example 2]

[0549] This example describes the detailed fabrication processes and properties of light-emitting devices 2-1 to 2-4, which are tandem light-emitting devices using organic electron-transport compounds (second organic compounds) with different LUMO levels for the first and second layers of the interlayers. Structural formulas of the main compounds used in this example are shown below. (Manufacturing method of the light-emitting device 2-1)

[0550] First, a 100 nm thick alloy of silver, palladium, and copper (Ag-Pd-Cu, also referred to as APC) and a 50 nm thick indium tin oxide containing silicon oxide (ITSO) were sequentially deposited on a glass substrate from the substrate side as a reflective electrode and a transparent electrode, respectively, by sputtering, forming the first electrode 101 with a size of 2 mm × 2 mm. Note that the transparent electrode serves as the anode, and the transparent electrode and the reflective electrode are collectively considered the first electrode 101.

[0551] Next, in a pretreatment for forming the light-emitting device over a substrate, the surface of the substrate was washed with water, and baking was performed at 200 °C for one hour.

[0552] The substrate was then transferred to a vacuum evaporation device where the pressure was increased to approximately 1 × 10 -4 Pa, and was subjected to vacuum baking for 30 minutes at 170 °C in a heating chamber of the vacuum evaporation device, and then the substrate was cooled for approximately 30 minutes.

[0553] The substrate provided with the first electrode 101 was then attached to a holder in the vacuum evaporation device such that the ...

Claims

[1] Light-emitting device comprising: a first light-emitting device; and a second light-emitting device, wherein the first light-emitting device comprises: a first electrode over an insulating surface; a second electrode facing the first electrode; and a first layer between the first electrode and the second electrode, wherein the second light-emitting device comprises: a third electrode above the insulating surface; the second electrode facing the third electrode; and a second layer between the third electrode and the second electrode, wherein the second electrode is a continuous conductive layer shared by the first light-emitting device and the second light-emitting device, wherein the second electrode and the first layer overlap with the first electrode, wherein the second electrode and the second layer overlap with the third electrode, wherein the first layer and the second layer each comprise a first light-emitting layer, a second light-emitting layer and an intermediate layer between the first light-emitting layer and the second light-emitting layer, wherein the intermediate layer comprises a first region comprising a first organic compound, a second organic compound and a metal or a metal oxide, wherein the first organic compound comprises a first π-electron-deficient heteroaromatic ring comprising an electron-donor group, wherein the second organic compound comprises a second π-electron-deficient heteroaromatic ring, wherein a LUMO level of the second organic compound is more than or equal to 0.20 eV lower than a LUMO level of the first organic compound, and wherein a distance between the first layer and the second layer is greater than or equal to 0.5 µm and less than or equal to 5 µm. [2] The light-emitting device according to claim 1, wherein when the LUMO level of the first organic compound is represented by LUMO1 (eV), LUMO2 (eV), which is the LUMO level of the second organic compound, satisfies LUMO1 - 0.50 ≤ LUMO2 ≤ LUMO1 - 0.

20. [3] The light-emitting device according to claim 1, wherein the first π-electron-deficient heteroaromatic ring is a heteroaromatic ring comprising two or more pyridine rings. [4] A light-emitting device according to claim 1, wherein an acid constant pK s of the first organic compound is greater than or equal to 8. [5] The light-emitting device according to claim 1, wherein the first π-electron-deficient heteroaromatic ring is different from the second π-electron-deficient heteroaromatic ring. [6] The light-emitting device according to claim 1, wherein the second organic compound comprises at least one of an imidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring, a triazole ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, and a triazine ring. [7] A light-emitting device according to claim 1, wherein an acid constant pK s of the second organic compound is less than 4. [8] A light-emitting device according to claim 1, wherein the first light-emitting layer is closer to the first electrode than the second light-emitting layer, wherein the first light-emitting layer comprises a third organic compound, wherein the third organic compound comprises a third π-electron-deficient heteroaromatic ring, and where the third π-electron-deficient heteroaromatic ring is equal to the second π-electron-poor heteroaromatic ring. [9] Light-emitting device according to claim 1, wherein the first light-emitting layer is closer to the first electrode than the second light-emitting layer, wherein the first light-emitting layer comprises a third organic compound, and where the third organic compound is equal to the second organic compound. [10] The light-emitting device according to claim 9, further comprising a first electron transport layer between the first light-emitting layer and the intermediate layer, wherein the first electron transport layer comprises a fourth organic compound, and where the fourth organic compound differs from the third organic compound. [11] The light-emitting device according to claim 1, wherein the metal belongs to one of Group 3, Group 11, Group 12 and Group 13. [12] The light-emitting device according to claim 1, wherein the electron donor group is one or more of an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group. [13] The light-emitting device according to claim 1, wherein the minimum value of an electrostatic potential of the first organic compound is less than or equal to -0.085 E h is when a threshold value of the electron density distribution in atomic units is 0.0004 e / a0 3 is. [14] The light-emitting device according to claim 1, wherein the first organic compound, the second organic compound and the metal or the metal oxide are mixed in the first region. [15] The light-emitting device according to claim 1, wherein a layer comprising the metal or the metal oxide and a layer in which the first organic compound and the second organic compound are mixed are stacked in the first region.

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