Light-emitting device, display device. light-emitting device, electronic apparatus, and illumination device

Abstract

To provide a light-emitting device with high luminous efficiency.SOLUTION: A light-emitting device includes a first electrode, a second electrode, and an EL layer provided between the first electrode and the second electrode. The EL layer includes at least a light-emitting layer, a first layer, a second layer, and a third layer. The first layer exists between the first electrode and the light-emitting layer; the third layer exists between the first layer and the light-emitting layer; and the second layer exists between the first layer and the third layer. The first layer contains a first organic compound; the second layer contains a second organic compound; and the third layer contains a third organic compound. The normal light refractive index of the second organic compound is higher than those of the first organic compound and the third organic compound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to organic compounds, light-emitting elements, light-emitting devices, display modules, lighting modules, display devices, light-emitting devices, electronic equipment, lighting devices, and electronic devices. However, one aspect of the present invention is not limited to the above-mentioned technical fields. The technical fields of one aspect of the invention disclosed herein relate to products, methods, or methods of manufacturing. Alternatively, one aspect of the present invention relates to processes, machines, manufacturers, or compositions of matter. More specifically, examples of the technical fields of one aspect of the present invention disclosed herein include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, energy storage devices, memory devices, imaging devices, methods for driving them, or methods for manufacturing them. [Background technology]

[0002] The practical application of light-emitting devices (organic EL devices) that utilize electroluminescence (EL) using organic compounds is progressing. The basic structure of these light-emitting devices is an organic compound layer (EL layer) containing a light-emitting material sandwiched between a pair of electrodes. By applying a voltage to this device, carriers are injected, and by utilizing the recombination energy of these carriers, light emission can be obtained from the light-emitting material.

[0003] Because these light-emitting devices are self-emissive, using them as pixels in a display offers advantages over liquid crystal displays, such as higher visibility and the elimination of the need for a backlight, making them particularly suitable for flat-panel displays. Another major advantage of displays using such light-emitting devices is that they can be manufactured to be thin and lightweight. Furthermore, they are characterized by their extremely fast response speed.

[0004] Furthermore, since these light-emitting devices can form a light-emitting layer continuously in two dimensions, they can produce light in a planar manner. This is a feature that is difficult to obtain with point light sources such as incandescent bulbs or LEDs, or line light sources such as fluorescent lamps, and therefore has high value as a planar light source that can be applied to lighting and other applications.

[0005] While displays or lighting devices using light-emitting devices are suitable for various electronic devices, research and development are underway to find light-emitting devices with even better characteristics.

[0006] One of the problems often raised when discussing organic EL devices is their low light extraction efficiency. To improve this, a configuration has been proposed in which a layer made of a low refractive index material is formed inside the EL layer (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent Application Publication No. 2020 / 0176692 [Non-patent literature]

[0008] [Non-Patent Document 1] Hiroshi Noguchi, et al., "Orientational Polarization Phenomena of Polar Molecules and Interface Properties of Organic Thin Film Devices," Journal of the Vacuum Society of Japan, 2015, Vol. 58, No. 3. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] One aspect of the present invention aims to provide a light-emitting device with high luminous efficiency. Alternatively, one aspect of the present invention aims to provide a light-emitting device, light-emitting apparatus, electronic device, display device, or electronic device with low power consumption.

[0010] The present invention only needs to solve one of the above-mentioned problems. [Means for solving the problem]

[0011] One aspect of the present invention is a light-emitting device comprising a first electrode, a second electrode, and an EL layer located between the first electrode and the second electrode, wherein the EL layer comprises at least a light-emitting layer, a first layer, a second layer, and a third layer, the first layer located between the first electrode and the light-emitting layer, the third layer located between the first layer and the light-emitting layer, the second layer located between the first layer and the third layer, the first layer comprising a first organic compound, the second layer comprising a second organic compound, and the third layer comprising a third organic compound, wherein the paraphotometric refractive index of the second organic compound at any wavelength between 450 nm and 650 nm is higher than that of the first organic compound at the said wavelength and the paraphotometric refractive index of the third organic compound at the said wavelength.

[0012] Alternatively, another aspect of the present invention is a light-emitting device comprising a first electrode, a second electrode, and an EL layer located between the first electrode and the second electrode, wherein the EL layer comprises at least a light-emitting layer, a first layer, a second layer, and a third layer, the first layer located between the first electrode and the light-emitting layer, the third layer located between the first layer and the light-emitting layer, the second layer located between the first layer and the third layer, the first layer comprising a first organic compound, the second layer comprising a second organic compound, and the third layer comprising a third organic compound, wherein the paraphotometric refractive index of the second organic compound at any wavelength between 455 nm and 465 nm is higher than the paraphotometric refractive index of the first organic compound at the said wavelength and the paraphotometric refractive index of the third organic compound at the said wavelength.

[0013] Alternatively, another aspect of the present invention is a light-emitting device comprising a first electrode, a second electrode, and an EL layer located between the first electrode and the second electrode, wherein the EL layer comprises at least a light-emitting layer, a first layer, a second layer, and a third layer, the first layer located between the first electrode and the light-emitting layer, the third layer located between the first layer and the light-emitting layer, the second layer located between the first layer and the third layer, the first layer comprising a first organic compound, the second layer comprising a second organic compound, and the third layer comprising a third organic compound, wherein the paraphotometric refractive index of the second organic compound at a wavelength of 633 nm is higher than that of the first organic compound and the paraphotometric refractive index of the third organic compound at a wavelength of 633 nm.

[0014] Alternatively, another aspect of the present invention is a light-emitting device comprising a first electrode, a second electrode, and an EL layer located between the first electrode and the second electrode, wherein the EL layer comprises at least a light-emitting layer, a first layer, a second layer, and a third layer, the first layer located between the first electrode and the light-emitting layer, the third layer located between the first layer and the light-emitting layer, the second layer located between the first layer and the third layer, the light-emitting layer comprising a light-emitting material exhibiting light emission with a peak wavelength of wavelength λnm, the first layer comprising a first organic compound, the second layer comprising a second organic compound, and the third layer comprising a third organic compound, wherein the paraphotometric refractive index of the second organic compound at the wavelength λnm is higher than that of the first organic compound at the wavelength λnm and the paraphotometric refractive index of the third organic compound at the wavelength λnm.

[0015] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the difference between the HOMO level of the first organic compound and the HOMO level of the third organic compound is 0.2 eV or less.

[0016] Alternatively, another aspect of the present invention is a light-emitting device in which the first organic compound and the third organic compound are the same organic compound in the above configuration.

[0017] Alternatively, another aspect of the present invention is a light-emitting device in which the third layer does not contain fluorine in the above configuration.

[0018] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the film thickness of each of the first to third layers is 25 nm or more and 70 nm or less.

[0019] Alternatively, in another aspect of the present invention, the light-emitting device is such that the thickness of the second layer is greater than the thickness of the first layer and the thickness of the third layer.

[0020] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the difference between the paraphoton refractive index of the second organic compound and the paraphoton refractive index of the first organic compound at a wavelength λnm, and the difference between the paraphoton refractive index of the second organic compound and the paraphoton refractive index of the third organic compound, are each 0.2 or more and less than 0.5.

[0021] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the difference in the ordinary refractive index of the first organic compound and the third organic compound at the wavelength λnm is 0.1 or less.

[0022] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the product of the film thickness of the second layer and the ordinary refractive index of the second organic compound at the wavelength λnm is 70% or more and 130% or less of 1 / 4 of the wavelength λnm.

[0023] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, λ is the peak wavelength of light emitted by the light-emitting material.

[0024] Alternatively, another aspect of the present invention is a light-emitting device in the above configuration in which λ is any value between 450 and 650.

[0025] Alternatively, another aspect of the present invention is a light-emitting device in the above configuration in which λ is any value between 455 and 465.

[0026] Alternatively, another aspect of the present invention is a light-emitting device in which λ is 633 in the above configuration.

[0027] Alternatively, in another aspect of the present invention, the first electrode in the above configuration is a light-emitting device that includes a reflective electrode.

[0028] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the value obtained by subtracting the GSP (mV / nm) of the second layer from the GSP (mV / nm) of the third layer is 10 (mV / nm) or less.

[0029] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the value obtained by subtracting the GSP (mV / nm) of the first layer from the GSP (mV / nm) of the second layer is 10 (mV / nm) or less.

[0030] Alternatively, another aspect of the present invention is a light-emitting device in which the GSP(mV / nm) of the third layer is greater than the GSP(mV / nm) of the second layer.

[0031] Alternatively, another aspect of the present invention is a light-emitting device in which the GSP(mV / nm) of the third layer is greater than the GSP(mV / nm) of the first layer.

[0032] Alternatively, another aspect of the present invention is a light-emitting device in which the GSP(mV / nm) of the second layer is greater than the GSP(mV / nm) of the first layer.

[0033] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the first organic compound and the third organic compound are different organic compounds.

[0034] Alternatively, another aspect of the present invention is a display device comprising a first light-emitting device and a second light-emitting device, wherein the first light-emitting device has the configuration described in any of the above, the second light-emitting device has an EL layer between a third electrode and the second electrode, the EL layer of the second light-emitting device comprises at least a light-emitting layer, a fourth layer, a fifth layer, and a sixth layer, wherein the fourth layer, the fifth layer, and the sixth layer have the same configuration as the first layer, the second layer, and the third layer, and the peak wavelength of emission of the light-emitting material contained in the light-emitting layer of the first light-emitting device differs from the peak wavelength of emission of the light-emitting material contained in the light-emitting layer of the second light-emitting device by 30 nm or more.

[0035] Alternatively, another aspect of the present invention is a display device having the light-emitting device described above, a sensor, an operation button, and a speaker or microphone.

[0036] Alternatively, another aspect of the present invention is an electronic device having the above-mentioned display device, a sensor, an operation button, and a speaker or microphone.

[0037] Alternatively, another aspect of the present invention is a light-emitting device having the light-emitting device described in any of the above descriptions, a transistor, or a substrate.

[0038] Alternatively, another aspect of the present invention is a lighting device having a light-emitting device as described above and a housing.

[0039] In this specification, the term "light-emitting device" includes image display devices that use light-emitting devices. Furthermore, modules to which connectors, such as anisotropic conductive films or TCPs (Tape Carrier Packages), are attached to light-emitting devices, modules to which printed circuit boards are provided at the end of TCPs, or modules to which ICs (integrated circuits) are directly mounted using the COG (Chip On Glass) method may also be included as light-emitting devices. Additionally, lighting fixtures and the like may have light-emitting devices. [Effects of the Invention]

[0040] In one aspect of the present invention, a light-emitting device with high luminous efficiency can be provided. Alternatively, in one aspect of the present invention, a light-emitting device, light-emitting apparatus, electronic device, display device, or electronic device with low power consumption can be provided.

[0041] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one aspect of the present invention does not necessarily have to possess all of these effects. Other effects will naturally become apparent from the description in the specification, drawings, and claims, and it is possible to extract other effects from the description in the specification, drawings, and claims. [Brief explanation of the drawing]

[0042] [Figure 1] Figures 1(A), 1(B), 1(C), and 1(D) are schematic diagrams of light-emitting devices. [Figure 2] Figures 2(A) and 2(B) are diagrams representing an active matrix type light-emitting device. [Figure 3] Figures 3(A) and 3(B) are diagrams representing an active matrix type light-emitting device. [Figure 4] Figure 4 is a diagram representing an active matrix type light-emitting device. [Figure 5] Figures 5(A) and 5(B) are diagrams representing passive matrix type light-emitting devices. [Figure 6]Figures 6(A) and 6(B) are diagrams representing lighting devices. [Figure 7] Figures 7(A), 7(B1), 7(B2), and 7(C) are diagrams representing electronic devices. [Figure 8] Figures 8(A), 8(B), and 8(C) are diagrams representing electronic devices. [Figure 9] Figure 9 is a diagram representing a lighting device. [Figure 10] Figure 10 is a diagram representing a lighting device. [Figure 11] Figure 11 is a diagram representing an in-vehicle display device and lighting system. [Figure 12] Figures 12(A) and 12(B) are diagrams representing electronic devices. [Figure 13] Figures 13(A), 13(B), and 13(C) are diagrams representing electronic devices. [Figure 14] Figures 14(A) to 14(D) show examples of the configuration of a display device. [Figure 15] Figures 15(A) to 15(F) show examples of methods for manufacturing a display device. [Figure 16] Figures 16(A) to 16(F) show examples of methods for manufacturing a display device. [Figure 17] Figure 17 shows the refractive indices of PCBDBtBB-02 and mmtBumTPoFBi-02. [Figure 18] Figure 18 shows the luminance-current density characteristics of light-emitting device 1, reference light-emitting device 1, and reference light-emitting device 2. [Figure 19] Figure 19 shows the luminance-voltage characteristics of light-emitting device 1, reference light-emitting device 1, and reference light-emitting device 2. [Figure 20] Figure 20 shows the current efficiency-luminance characteristics of light-emitting device 1, reference light-emitting device 1, and reference light-emitting device 2. [Figure 21] Figure 21 shows the current density-voltage characteristics of light-emitting device 1, reference light-emitting device 1, and reference light-emitting device 2. [Figure 22]Figure 22 shows the blue index-luminance characteristics of light-emitting device 1, reference light-emitting device 1, and reference light-emitting device 2. [Figure 23] Figure 23 shows the emission spectra of light-emitting device 1, reference light-emitting device 1, and reference light-emitting device 2. [Figure 24] Figure 24 shows the refractive indices of BBA(βN2)B-03 and mmtBuBioFBi. [Figure 25] Figure 25 shows the luminance-current density characteristics of the light-emitting device 10 and the comparison light-emitting device 10. [Figure 26] Figure 26 shows the luminance-voltage characteristics of the light-emitting device 10 and the comparison light-emitting device 10. [Figure 27] Figure 27 shows the current efficiency-luminance characteristics of the light-emitting device 10 and the comparative light-emitting device 10. [Figure 28] Figure 28 shows the current density-voltage characteristics of the light-emitting device 10 and the comparison light-emitting device 10. [Figure 29] Figure 29 shows the blue index-current density characteristics of the light-emitting device 10 and the comparison light-emitting device 10. [Figure 30] Figure 30 shows the emission spectra of the light-emitting device 10 and the reference light-emitting device 10. [Figure 31] Figure 31 shows the viewing angle characteristics of the light-emitting device 10 and the comparison light-emitting device 10. [Figure 32] Figure 32 shows the relative luminance-time variation characteristics of the light-emitting device 10 and the comparison light-emitting device 10. [Figure 33] Figure 33 shows the luminance-current density characteristics of the light-emitting device 20. [Figure 34] Figure 34 shows the luminance-voltage characteristics of the light-emitting device 20. [Figure 35] Figure 35 shows the current efficiency-luminance characteristics of the light-emitting device 20. [Figure 36] Figure 36 shows the current density-voltage characteristics of the light-emitting device 20. [Figure 37]Figure 37 shows the blue index-luminance characteristics of the light-emitting device 20. [Figure 38] Figure 38 shows the emission spectrum of the light-emitting device 20. [Figure 39] Figure 39 shows the normalized luminance-time variation characteristics of the light-emitting device 20. [Figure 40] Figure 40 shows the luminance-current density characteristics of the light-emitting device 30. [Figure 41] Figure 41 shows the luminance-voltage characteristics of the light-emitting device 30. [Figure 42] Figure 42 shows the current efficiency-luminance characteristics of the light-emitting device 30. [Figure 43] Figure 43 shows the current density-voltage characteristics of the light-emitting device 30. [Figure 44] Figure 44 shows the blue index-current density characteristics of the light-emitting device 30. [Figure 45] Figure 45 shows the emission spectrum of the light-emitting device 30. [Figure 46] Figure 46 shows the relative luminance-time variation characteristics of the light-emitting device 30. [Figure 47] Figures 47(A) and 47(B) show the refractive indices of BBA(βN2)B-03, mmtBuBioFBi, and mmtBumTPoFBi-04. [Figure 48] Figure 48 shows the luminance-current density characteristics of light-emitting device 40, light-emitting device 41, and comparison light-emitting device 40. [Figure 49] Figure 49 shows the current efficiency-luminance characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40. [Figure 50] Figure 50 shows the luminance-voltage characteristics of light-emitting device 40, light-emitting device 41, and comparison light-emitting device 40. [Figure 51] Figure 51 shows the current density-voltage characteristics of light-emitting device 40, light-emitting device 41, and comparison light-emitting device 40. [Figure 52]Figure 52 shows the blue index-luminance characteristics of light-emitting device 40, light-emitting device 41, and comparison light-emitting device 40. [Figure 53] Figure 53 shows the power efficiency-luminance characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40. [Figure 54] Figure 54 shows the emission spectra of light-emitting device 40, light-emitting device 41, and comparison light-emitting device 40. [Figure 55] Figure 55 shows the normalized luminance-time variation characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40. [Figure 56] Figure 56 shows the comparison light-emitting device 50 and the brightness-current density characteristics of the light-emitting device 50. [Figure 57] Figure 57 shows the comparison light-emitting device 50 and the brightness-voltage characteristics of the light-emitting device 50. [Figure 58] Figure 58 shows the current efficiency-luminance characteristics of the comparative light-emitting device 50 and the light-emitting device 50. [Figure 59] Figure 59 shows the current density-voltage characteristics of the comparison light-emitting device 50 and the light-emitting device 50. [Figure 60] Figure 60 shows the power efficiency-luminance characteristics of the comparative light-emitting device 50 and the light-emitting device 50. [Figure 61] Figure 61 shows the comparison light-emitting device 50 and the emission spectrum of the light-emitting device 50. [Figure 62] Figures 62(A) and 62(B) show the refractive indices of mmtBumTPoFBi-04, PCBBiPDBt-02, and mmtBuBiFF. [Figure 63] Figure 63 shows the refractive indices of mmtBumBPTzn, Li-6mq, and BisBTc. [Figure 64] Figure 64 shows the refractive indices of mmtBumTPoFBi-04, DBfBB1TP, and mmtBuBioFBi. [Figure 65]Figure 65 shows the emission spectrum of DPhA-tBu4DABNA in a toluene solution. [Figure 66] Figure 66 shows the luminance-current density characteristics of the light-emitting device 60. [Figure 67] Figure 67 shows the current efficiency-luminance characteristics of the light-emitting device 60. [Figure 68] Figure 68 shows the luminance-voltage characteristics of the light-emitting device 60. [Figure 69] Figure 69 shows the current density-voltage characteristics of the light-emitting device 60. [Figure 70] Figure 70 shows the blue index-luminance characteristics of the light-emitting device 60. [Figure 71] Figure 71 shows the emission spectrum of the light-emitting device 60. [Modes for carrying out the invention]

[0043] The embodiments of the present invention will be described in detail below with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and that its form and details can be modified in various ways without departing from the spirit and scope of the present invention. Accordingly, the present invention shall not be interpreted as being limited to the contents of the embodiments shown below.

[0044] When light is incident on a material with optical anisotropy, the light from a vibration plane parallel to the optical axis is called the extraordinary ray, and the light from a vibration plane perpendicular to it is called the ordinary ray. However, the refractive index of the material for the ordinary ray and the refractive index for the extraordinary ray may differ. In such cases, anisotropy analysis can be performed to separate the refractive index of the ordinary ray and the refractive index of the extraordinary ray and calculate the refractive index of each. In this specification, if both the ordinary ray refractive index and the extraordinary ray refractive index are present in the measured material, the ordinary ray refractive index will be used as the index.

[0045] (Embodiment 1) Figure 1(A) shows a diagram representing a light-emitting device according to one embodiment of the present invention. The light-emitting device shown in Figure 1(A) has a first electrode 101, a second electrode 102, and an EL layer 103. The EL layer 103 has at least a hole transport layer 112 (a first hole transport layer 112-1, a second hole transport layer 112-2, and a third hole transport layer 112-3) and a light-emitting layer 113. The light-emitting layer 113 is a layer having at least a light-emitting material, and the hole transport layer 112 is located between the light-emitting layer 113 and the first electrode 101. The EL layer 103 may also have a hole injection layer 111, an electron transport layer 114, and an electron injection layer 115, as shown in the figure, and may also have other functional layers such as a carrier block layer or exciton block layer, or an intermediate layer.

[0046] In one aspect of the present invention, the first hole transport layer 112-1 to the third hole transport layer 112-3 each contain the first to third organic compounds, and the first to third organic compounds are present in each of the first to third hole transport layers 112-1 to the third hole transport layer 112-3 at a concentration of 80% or more.

[0047] Furthermore, in a light-emitting device according to one embodiment of the present invention, the second organic compound has a higher paraphotometric refractive index than the first organic compound and the third organic compound. That is, the second hole transport layer 112-2 is a layer with a higher paraphotometric refractive index than the first hole transport layer 112-1 and the third hole transport layer 112-3.

[0048] With this configuration, the light-emitting device according to one aspect of the present invention can reflect more light than would be possible using only reflective electrodes, because the light emitted by the light-emitting material is reflected at the interface of each hole transport layer. This improves the external quantum efficiency. At the same time, the influence of surface plasmons at the reflective electrodes can be reduced, thus reducing energy loss and enabling efficient light extraction.

[0049] In one aspect of the present invention, it is preferable that the difference between the paraphotorefractive index of the second organic compound and the paraphotorefractive index of the first organic compound with respect to light of a certain wavelength λnm, and the difference between the paraphotorefractive index of the second organic compound and the paraphotorefractive index of the third organic compound, are each 0.1 or more and less than 0.5, preferably 0.2 or more and less than 0.5, and more preferably 0.3 or more and less than 0.5. Having these differences in paraphotorefractive index within the above range makes it less likely that problems will occur when applying a hole transport layer 112 having the same configuration as this light-emitting device to other light-emitting devices containing light-emitting materials that exhibit light of different wavelengths, and eliminates the need to create separate hole transport layers 112 for each emission color, thus providing a cost advantage.

[0050] Furthermore, it is more preferable that the difference between the paraphotometric refractive index of the second hole transport layer 112-2 and the paraphotometric refractive index of the first hole transport layer 112-1 for light of wavelength λnm, and the difference between the paraphotometric refractive index of the second hole transport layer 112-2 and the paraphotometric refractive index of the third hole transport layer 112-3, are each between 0.2 and less than 0.5. The wavelength λnm is any of the ranges from 450nm to 650nm or the entire range, and if the light-emitting device exhibits blue emission, the wavelength λnm is any of the ranges from 455nm to 465nm or the entire range. In addition, it is preferable that the wavelength λnm is the emission peak wavelength of the light-emitting material. Note that the wavelength λnm commonly used as an index for refractive index is 633nm. These values ​​may be used as an index for the wavelength λnm.

[0051] The paraphotometric refractive indices of the first and third organic compounds at a wavelength of λnm are preferably 1.40 or more and 1.75 or less. More specifically, the paraphotometric refractive index in the blue emission region (455nm to 465nm) is preferably 1.40 or more and 1.75 or less, or the paraphotometric refractive index at 633nm light, which is commonly used for refractive index measurement, is preferably 1.40 or more and 1.70 or less. It is even more preferable that the paraphotometric refractive indices of the first hole transport layer 112-1 and the third hole transport layer 112-3 are within the above range. Furthermore, it is preferable that the difference between the paraphotometric refractive indices of the first organic compound and the third organic compound at a wavelength of λnm is 0.1 or less.

[0052] The paraphotometric refractive index of the second organic compound at a wavelength of λnm is preferably 1.75 or higher. More specifically, the paraphotometric refractive index in the blue emission region (455nm to 465nm) is preferably 1.75 to 2.4, or the paraphotometric refractive index at 633nm, which is commonly used for refractive index measurement, is preferably 1.75 to 2.30. It is even more preferable that the paraphotometric refractive index of the second hole transport layer 112-2 is within the above range.

[0053] Furthermore, it is preferable that the difference in HOMO levels between the first organic compound and the third organic compound is 0.2 eV or less, preferably 0.1 eV or less, as this enhances hole transportability. Also, it is preferable that the difference in HOMO levels between the second organic compound and the first and third organic compounds is 0.2 eV or less, preferably 0.1 eV or less, as this enhances hole transportability.

[0054] In one aspect of the present invention, the film thickness of the first hole transport layer 112-1 to the third hole transport layer 112-3 is preferably 25 nm or more and 70 nm or less. In one aspect of the present invention, the characteristics of the light-emitting device are improved by installing buffer layers such as a hole injection layer or an electron blocking layer on the side of the first hole transport layer 112-1 and the third hole transport layer 112-3 that is not in contact with the second hole transport layer 112-2. Therefore, it is preferable that the film thickness of the second hole transport layer 112-2 is thicker than the film thickness of the first hole transport layer 112-1 and the third hole transport layer 112-3. Furthermore, it is preferable that the product of the ordinary refractive index of the second hole transport layer 112-2 at a wavelength λnm and the film thickness is 70% to 130% of λ / 4, as this strengthens light interference. By adopting this configuration, the light reflected at the interface between the third hole transport layer 112-3 and the second hole transport layer 112-2, and the light reflected at the interface between the second hole transport layer 112-2 and the first hole transport layer 112-1 can be amplified by interference, thereby providing a more efficient light-emitting device.

[0055] Furthermore, it is preferable that the first organic compound and the third organic compound are the same organic compound, as this ensures high hole transportability and reduces the amount of material used in fabricating the light-emitting device. In addition, it is preferable that the third hole transport layer 112-3 does not contain fluorine in order to ensure reliability. Moreover, since it is undesirable for optical interference that enhances specific light to become too strong when used as a common hole transport layer for a display device with the three primary colors of red, green, and blue, it is preferable that the first organic compound and the third organic compound do not contain fluorine, which has a low atomic refraction.

[0056] The first hole transport layer 112-1 and the third hole transport layer 112-3 are formed using materials with relatively low refractive indices, but there is usually a trade-off between high carrier transport and low refractive index. This is because carrier transport in organic compounds largely depends on the presence of unsaturated bonds, and organic compounds with many unsaturated bonds tend to have high refractive indices. Even if a material has a low refractive index, if its carrier transport is also low, problems such as an increase in driving voltage, a decrease in luminescence efficiency or reliability due to an imbalance in carriers will occur, making it impossible to obtain a light-emitting device with good characteristics. Furthermore, even if a material has sufficient carrier transport and a low refractive index, if it has an unstable structure, problems with the glass transition temperature (Tg) or durability will occur, making it impossible to obtain a light-emitting device with good reliability.

[0057] Therefore, as organic compounds that can be used in the first hole transport layer 112-1 and the third hole transport layer 112-3, it is preferable to use monoamine compounds having a first aromatic group, a second aromatic group, and a third aromatic group, wherein these first, second, and third aromatic groups are bonded to the same nitrogen atom.

[0058] The monoamine compound preferably has a ratio of 23% to 55% of the total number of carbon atoms in the molecule that form bonds via sp3 hybrid orbitals. 1It is preferable that the compound is such that the integrated value of the signal below 4 ppm exceeds the integrated value of the signal at 4 ppm or higher in the result of measuring the monoamine compound by 1H-NMR.

[0059] Moreover, it is preferable that the monoamine compound has at least one fluorene skeleton, and any one or more of the first aromatic group, the second aromatic group, and the third aromatic group is a fluorene skeleton. Since fluorenylamine has the effect of raising the HOMO level, when three fluorenes are bonded to the nitrogen of the monoamine compound, the HOMO level may increase significantly. In this case, the difference from the HOMO level of the surrounding material (for example, the HOMO level of the second organic compound) becomes large, which may affect the driving voltage and reliability. Therefore, it is more preferable that any one or two of the first aromatic group, the second aromatic group, and the third aromatic group is a fluorene skeleton.

[0060] Examples of the organic compound having the above hole-transporting property include organic compounds having structures such as the following general formula (G h1 1) to (G h1 4).

[0061]

Chemical formula

[0062] In the above general formula (G h1 1), Ar 1 , Ar 2 each independently represents a benzene ring or a substituent in which two or three benzene rings are bonded to each other. However, one or both of Ar 1 , Ar 2 has one or more hydrocarbon groups having 1 to 12 carbon atoms in which carbon makes bonds only with sp3 hybrid orbitals, and the total number of carbon atoms contained in all the hydrocarbon groups bonded to Ar 1 and Ar 2 is 8 or more, and Ar 1 and Ar 2The total number of carbon atoms in all the hydrocarbon groups bonded to either one of the above is 6 or more. 1 or Ar 2 If multiple linear alkyl groups having 1 or 2 carbon atoms are bonded to the hydrocarbon group, these linear alkyl groups may be bonded to each other to form a ring.

[0063] [ka]

[0064] The above general formula (G h1 In (2), m and r each independently represent 1 or 2, and m+r is 2 or 3. Also, t represents an integer from 0 to 4, and is preferably 0. 5 represents either hydrogen or a hydrocarbon group having 1 to 3 carbon atoms. Note that when m is 2, the type of substituents, the number of substituents, and the bond positions of the two phenylene groups may be the same or different, and when r is 2, the type of substituents, the number of substituents, and the bond positions of the two phenyl groups may be the same or different. Also, when t is an integer from 2 to 4, multiple R 5 Each of them may be the same or different, R 5 In this case, adjacent groups may be bonded to each other to form a ring.

[0065] [ka]

[0066] The above general formula (G h1 2) and (G h1 In 3), n and p each independently represent 1 or 2, and n+p is 2 or 3. s represents an integer from 0 to 4, and is preferably 0. Also, R 4n represents either hydrogen or a hydrocarbon group having 1 to 3 carbon atoms. When n is 2, the type of substituents, the number of substituents, and the position of the bonds of the two phenylene groups may be the same or different. When p is 2, the type of substituents, the number of substituents, and the position of the bonds of the two phenyl groups may be the same or different. Also, when s is an integer from 2 to 4, multiple R 4 These can be the same or different.

[0067] [ka]

[0068] The above general formula (G h1 2)~(G h1 In 4), R 10 ~R 14 and R 20 ~R 24 Each of these independently represents a hydrocarbon group with 1 to 12 carbon atoms, in which hydrogen or carbon atoms form bonds solely through sp3 hybrid orbitals. 10 ~R 14 At least three of the following, and R 20 ~R 24 It is preferable that at least three of them are hydrogen. As hydrocarbon groups having 1 to 12 carbon atoms in which carbon atoms form bonds only with sp3 hybrid orbitals, tert-butyl groups and cyclohexyl groups are preferred. However, R 10 ~R 14 and R 20 ~R 24 The total amount of carbon contained in is 8 or more, and R 10 ~R 14 or R 20 ~R 24 The total number of carbon atoms in either of the two is assumed to be 6 or more. 4 , R 10 ~R 14 and R 20 ~R 24 In this case, adjacent groups may be bonded to each other to form a ring.

[0069] Also, the above general formula (Gh1 1)~(G h1 4) In this case, each u independently represents an integer from 0 to 4, and is preferably 0. If u is an integer from 2 to 4, multiple R 3 These can be the same or different. Also, R 1 , R 2 and R 3 Each of these independently represents an alkyl group having 1 to 4 carbon atoms, R 1 and R 2 They may be joined to each other to form a ring.

[0070] Furthermore, as one of the hole-transporting materials that can be used in the first hole transport layer 112-1 and the third hole transport layer 112-3, an arylamine compound having at least one aromatic group, wherein the aromatic group has a first to third benzene ring and at least three alkyl groups, is also preferred. The first to third benzene rings are bonded in this order, and the first benzene ring is directly bonded to the nitrogen of the amine.

[0071] Furthermore, the first benzene ring may have substituted or unsubstituted phenyl groups, and it is preferable that it has unsubstituted phenyl groups. Also, the second or third benzene ring may have alkyl-substituted phenyl groups.

[0072] Furthermore, of the first to third benzene rings, hydrogen is not directly bonded to the carbon atoms at positions 1 and 3 of two or more benzene rings, preferably all of them, but is bonded to any of the first to third benzene rings, the alkyl-substituted phenyl group, the three alkyl groups, or the nitrogen atom of the amine.

[0073] Furthermore, the arylamine compound preferably has a second aromatic group. The second aromatic group is preferably an unsubstituted monocycle or a substituted or unsubstituted fused ring of three or fewer rings, and more preferably a substituted or unsubstituted fused ring of three or fewer rings, wherein the fused ring has 6 to 13 carbon atoms forming the ring, and even more preferably a group having a fluorene ring. Dimethylfluorenyl is preferred as the second aromatic group.

[0074] Furthermore, it is preferable that the above arylamine compound further has a third aromatic group. The third aromatic group is a group having one to three substituted or unsubstituted benzene rings.

[0075] The at least three alkyl groups mentioned above, and the alkyl group substituted for the phenyl group, are preferably chain alkyl groups having 2 to 5 carbon atoms. In particular, branched chain alkyl groups having 3 to 5 carbon atoms are preferred, and t-butyl groups are even more preferred.

[0076] Examples of materials exhibiting the hole transport properties described above include those using the following general formula (G h2 1)~(G h2 Examples of organic compounds having a structure like that in 3) are given.

[0077] [ka]

[0078] Note that the above general formula (G h2 1) In Ar 101 represents a substituted or unsubstituted benzene ring, or a substituent consisting of two or three substituted or unsubstituted benzene rings bonded to each other.

[0079] [ka]

[0080] Note that the above general formula (G h2 In (2), x and y each independently represent 1 or 2, and x+y is 2 or 3. Also, R 109 represents an alkyl group with 1 to 4 carbon atoms, and w represents an integer from 0 to 4. Also, R 141 ~R 145 Each of these independently represents one of the following: hydrogen, an alkyl group having 1 to 6 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms. If w is an integer of 2 or more, multiple R 109 These may be the same or different. Also, if x is 2, the type of substituents, the number of substituents, and the position of the bond on the two phenylene groups may be the same or different. Also, if y is 2, the two R 141 ~R 145 The types and number of substituents on the phenyl group having the same substituent may be the same or different.

[0081] [ka]

[0082] Note that the above general formula (G h2 3) In R 101 ~R 105 Each of these independently represents one of the following: hydrogen, a C1 to C6 alkyl group, a C6 to C12 cycloalkyl group, or a substituted or unsubstituted phenyl group.

[0083] Also, the above general formula (G h2 1)~(G h2 3) In R 106 , R 107 and R 108 Each of these independently represents an alkyl group having 1 to 4 carbon atoms, and v represents an integer from 0 to 4. Note that if v is 2 or greater, multiple R groups are used. 108 These can be the same or different. Also, R 111 ~R 115One is a substituent represented by the above general formula (g1), and the rest each independently represent any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted phenyl group. In the above general formula (g1), R 121 to R 125 One is a substituent represented by the above general formula (g2), and the rest each independently represent any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms. In the above general formula (g2), R 131 to R 135 Each independently represents any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms. Note that among R 111 to R 115 , R 121 to R 125 and R 131 to R 135 , at least 3 or more are alkyl groups having 1 to 6 carbon atoms, the substituted or unsubstituted phenyl group in R 111 to R 115 is 1 or less, and the phenyl group substituted with an alkyl group having 1 to 6 carbon atoms in R 121 to R 125 and R 131 to R 135 is 1 or less. Also, in at least 2 combinations out of the 3 combinations of R 112 and R 114 , R 122 and R 124 , and R 132 and R 134 , at least one R is other than hydrogen.

[0084] Organic compounds having hole transport properties as described above have an ordinary refractive index of 1.40 to 1.75 in the blue light emission region (455 nm to 465 nm), or an ordinary refractive index of 1.40 to 1.70 at 633 nm light, which is commonly used for refractive index measurement, and possess good hole transport properties. It is also possible to obtain organic compounds with high Tg and good reliability at the same time. Since such organic compounds also possess sufficient hole transport properties, they can be suitably used as materials for the first hole transport layer 112-1 and the third hole transport layer 112-3.

[0085] In addition, other compounds such as 1,1-bis[4-[N,N-di(p-tolyl)amino]phenyl]cyclohexane (abbreviated as TAPC) can also be used.

[0086] Furthermore, the second hole transport layer 112-2 is formed using an organic compound with a relatively high refractive index, and such organic compounds are preferably those having a condensed aromatic hydrocarbon ring or a condensed heteroaromatic ring. As the condensed aromatic hydrocarbon ring, those containing a naphthalene structure, such as a naphthalene ring, anthracene ring, phenanthrene ring, or triphenylene ring, are preferred, and as the condensed heteroaromatic ring, those containing the structures of a carbazole ring, a dibenzofuran ring, or a dibenzothiophene ring are preferred. Also, for example, benzo[b]naphtho[1,2-d]furan is preferred because it contains the structure of a dibenzofuran ring.

[0087] Furthermore, organic compounds containing one or more elements from the third period or later, organic compounds having a terphenyl skeleton, or organic compounds containing both are suitably used. For example, a biphenyl group substituted with a naphthyl group or a phenyl group substituted with a dibenzofuranyl group can be said to contain a terphenyl skeleton. Specifically, N,N-bis[4-(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)phenyl]-4-amino-p-terphenyl (abbreviation: BnfBB1TP), 4,4'-bis[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: βNBiB1BP), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), 4-[4'-(carbazole-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBiβNB), 5,5'-diphenyl-2,2'-di-5H-[1]benzothieno[3,2-c]carbazole (abbreviation: BisBTc), etc., can be suitably used.

[0088] Furthermore, the first electrode 101 preferably includes a reflective electrode that reflects 40% or more, preferably 70% or more, of visible light. The second electrode 102 is preferably a semi-transparent / semi-reflective electrode with a visible light reflectance of 20% to 80%, preferably 40% to 70%. With such a configuration, one embodiment of the present invention becomes a top-emission type light-emitting device that emits light from the second electrode 102 side, and can be made into a light-emitting device having a microcavity structure by adjusting the film thickness of the EL layer.

[0089] In this configuration, the optical distance between the interface of the reflective electrode on the EL layer 103 side and the interface of the first hole transport layer 112-1 on the reflective electrode side is preferably λ / 8 to 3λ / 8. Furthermore, the optical distance between the main light-emitting region of the light-emitting layer 113 and the interface of the first hole transport layer 112-1 on the reflective electrode side is preferably 3λ / 8 to 5λ / 8. Furthermore, the optical distance between the interface of the reflective electrode on the EL layer 103 side and the interface of the third hole transport layer 112-3 on the reflective electrode side is preferably 3λ / 8 to 5λ / 8. Furthermore, the optical distance between the main light-emitting region of the light-emitting layer 113 and the interface of the third hole transport layer 112-3 on the light-emitting layer side is preferably λ / 8 to 3λ / 8. With this configuration, the light reflected at the interfaces of each layer and the reflective electrode amplifies each other, making it possible to create a light-emitting device with good efficiency and good color purity. If it is difficult to accurately determine the main light-emitting region of the light-emitting layer, the estimated position, taking into account the transportability of the light-emitting layer, can be used as the reference point.

[0090] Incidentally, in one aspect of the present invention, the light extraction efficiency is improved by stacking multiple hole transport layers with different refractive indices. However, this also results in a light-emitting device with more layers than a typical light-emitting device, which increases the number of layer interfaces, making it easier for interface-derived resistance to occur and potentially causing the driving voltage to rise.

[0091] Typically, in the hole transport region of organic semiconductor devices, considering hole exchange with the electrode, it is necessary to sequentially inject holes into layers made of organic compounds having different HOMO levels from the active layer or light-emitting layer. Naturally, if the difference in HOMO levels between each layer is too large, the driving voltage will increase. Therefore, to mitigate this difference in HOMO levels, a layer made of organic compounds having a HOMO level located between the HOMO levels of the electrode and the active layer (light-emitting layer) is placed between them. However, even with layers where the difference in HOMO levels is not so large, the driving voltage could increase significantly depending on the combination of organic compounds used. Until now, there have been no guidelines to avoid this, and it has been dismissed as a matter of material compatibility.

[0092] On the other hand, organic compounds include both polar and nonpolar molecules. Polar molecules have a permanent dipole moment, but when polar molecules are deposited, if the deposited film is randomly oriented, these polar biases cancel each other out and no polarization originating from the molecular polarity occurs within the film. However, if the deposited film has molecular orientation, a giant surface potential originating from the polarization bias may appear.

[0093] Giant surface potential is a phenomenon in which the surface potential of a deposited film increases in proportion to its film thickness. This can be explained as a spontaneous orientation polarization phenomenon caused by a slight bias in the direction of film thickness of the permanent dipole moment of the organic compound. To treat its magnitude as a value independent of film thickness, the value obtained by dividing the surface potential of the deposited film by the film thickness, i.e., the potential gradient (slope) of the surface potential of the deposited film, can be used. In this specification, this potential gradient of the surface potential of the deposited film is referred to as GSP (mV / nm).

[0094] By considering this GSP value, it becomes possible to eliminate the mismatches that have been associated with the compatibility of conventional materials, as described above, and to easily obtain organic semiconductor devices with good properties.

[0095] In one aspect of the present invention, the GSP of the third hole transport layer 112-3 is subtracted from the GSP of the first hole transport layer 112-1 (ΔGSP). 1-3 It is preferable that the GSP of the second hole transport layer 112-2 is 10 (mV / nm) or less, and more preferably 0 (mV / nm) or less. Also, the value obtained by subtracting the GSP of the third hole transport layer 112-3 from the GSP of the second hole transport layer 112-2 (ΔGSP) 2-3 It is preferable that the ΔGSP is 10 (mV / nm) or less, and more preferably 0 (mV / nm) or less. 1-3 and ΔGSP 2-3 It is more preferable that both are 10 (mV / nm) or less, and even more preferable that they are 0 (mV / nm) or less.

[0096] Note that the GSP of the second hole transport layer 112-2 is subtracted from the GSP of the first hole transport layer 112-1 (ΔGSP). 1-2It is preferable that the value is 10 (mV / nm) or less, and even more preferable that it is 0 (mV / nm) or less.

[0097] This configuration makes it easy to obtain a light-emitting device with good characteristics such as low drive voltage, low power consumption, or high power efficiency.

[0098] Furthermore, it is preferable that the GSP of the third hole transport layer 112-3 is higher than that of the first hole transport layer 112-1, and also preferable that the GSP of the third hole transport layer 112-3 is higher than that of the second hole transport layer 112-2. More preferably, the GSP of the third hole transport layer 112-3 is higher than that of both the first hole transport layer 112-1 and the second hole transport layer 112-2. By having this configuration, it is possible to obtain a light-emitting device with good characteristics such as a lower driving voltage, lower power consumption, or higher power efficiency.

[0099] Furthermore, it is preferable that the GSP of the second hole transport layer 112-2 is higher than that of the first hole transport layer 112-1. This configuration makes it easier to obtain a light-emitting device with good characteristics such as a low driving voltage, low power consumption, or high power efficiency.

[0100] The GSP of each layer can be determined by measuring the GSP of the vapor-deposited film of the material (organic compound) that constitutes each layer.

[0101] This section explains how to determine the GSP (Global Spread Spectrum) of organic compounds.

[0102] Generally, the slope of the surface potential of a deposited film plotted in the film thickness direction using Kelvin probe measurements is discussed as the magnitude of the giant surface potential, i.e., GSP (mV / nm). However, when two different layers are stacked, the polarization charge density (mC / m) accumulated at their interface is also discussed. 2 The GSP can be estimated by utilizing the fact that ) changes in relation to the GSP.

[0103] Non-patent document 1 shows that when organic thin films with different spontaneous polarizations (thin film 1 and thin film 2, where thin film 1 is on the anode side and thin film 2 is on the cathode side) are stacked and an electric current is passed through them, the following equation holds true.

[0104]

number

[0105]

number

[0106] In equation (1), σ if V is the polarization charge density. i V is the hole injection voltage. bi V is the threshold voltage, d2 is the thickness of thin film 2, and ε2 is the dielectric constant of thin film 2. i , V bi This can be estimated from the capacitance-voltage characteristics of the device. Furthermore, the dielectric constant is the refractive index n. o The square of (633nm) can be used. In this way, V estimated from the capacitance-voltage characteristics i , V bi Then, using the dielectric constant ε2 of thin film 2 calculated from the refractive index, and the film thickness d2 of thin film 2, the polarization charge density σ is calculated using equation (1). if It is possible to find this.

[0107] Next, in equation (2), σ if P is the polarization charge density. n This is the GSP of thin film n, ε n σ is the dielectric constant of the thin film n. Here, from equation (1) above, the polarization charge density σ if Since this can be determined, the GSP of thin film 1 can be estimated by using a material with a known GSP as thin film 2.

[0108] As described above, the GSP can be determined by the above method using the vapor-deposited film of the organic compound for which the GSP is to be determined as thin film 1.

[0109] In this specification, Alq3, which has a known GSP of 48 (mV / nm), was used as thin film 2, and the GSP of each thin film was determined.

[0110] Furthermore, it is known that the orientation of the deposited film depends on the substrate temperature during deposition, and similarly, the GSP value may also depend on the substrate temperature during deposition. The measurements used in this specification are those of films deposited at room temperature during deposition.

[0111] Next, examples of other structures and materials for a light-emitting device according to one aspect of the present invention will be described. As described above, a light-emitting device according to one aspect of the present invention has an EL layer 103 consisting of multiple layers between a pair of electrodes, a first electrode 101 and a second electrode 102, and the EL layer 103 has a light-emitting layer 113 having at least a light-emitting material and a hole transport layer 112 (a first hole transport layer 112-1, a second hole transport layer 112-2, and a third hole transport layer 112-3).

[0112] The first electrode 101 is preferably formed using a metal, alloy, conductive compound, or mixture thereof with a large work function (specifically, 4.0 eV or more). Specifically, examples include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, and indium oxide (IWZO) containing tungsten oxide and zinc oxide. These conductive metal oxide films are usually deposited by sputtering, but they may also be fabricated using methods such as the sol-gel method. As an example of a fabrication method, indium zinc oxide can be formed by sputtering using a target containing 1 to 20 wt% zinc oxide relative to indium oxide. Indium oxide (IWZO) containing tungsten oxide and zinc oxide can also be formed by sputtering using a target containing 0.5 to 5 wt% tungsten oxide and 0.1 to 1 wt% zinc oxide relative to indium oxide. Other materials that can be used for the first electrode 101 include, for example, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or nitrides of metallic materials (e.g., titanium nitride). Alternatively, graphene can also be used as the material for the first electrode 101. Furthermore, by using the composite material described later in the layer in contact with the first electrode 101 in the EL layer 103 (typically the hole injection layer 111), the electrode material can be selected regardless of the work function.

[0113] Furthermore, if the first electrode 101 is formed of a material that is transparent to the light emitted by the light-emitting device, the light-emitting device can be made to emit light from the side of the first electrode 101, as shown in Figure 1(C). Also, if the first electrode 101 includes an electrode that is reflective to the light emitted by the light-emitting device, and the second electrode 102 is formed of a material that is transparent to the light emitted by the light-emitting device, the light-emitting device can be made to emit light from the side of the second electrode 102, as shown in Figure 1(D). Since the hole transport layer 112 is provided between the light-emitting layer 113 and the first electrode 101, it is preferable that the first electrode 101 includes an electrode that is reflective to the light emitted by the light-emitting device.

[0114] The EL layer 103 preferably has a multilayer structure, but there are no particular limitations on the multilayer structure other than the light-emitting layer 113 and hole transport layer 112, and various functional layers such as hole injection layers, electron transport layers, electron injection layers, carrier block layers (hole block layers, electron block layers), exciton block layers, intermediate layers, and charge generation layers can be used. Note that any of the layers may not be provided. In this embodiment, two types of configurations will be described, as shown in Figure 1(A), in which a hole injection layer 111, an electron transport layer 114, and an electron injection layer 115 are provided in addition to the light-emitting layer 113 and hole transport layer 112, and as shown in Figure 1(B), in which a charge generation layer 116 is provided instead of the electron injection layer 115.

[0115] The hole injection layer 111 is provided in contact with the first electrode 101 and has the function of facilitating the injection of holes into the EL layer 103. The hole injection layer 111 can be formed from phthalocyanine-based complex compounds such as phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine (abbreviated as CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) and 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviated as DNTPD), or polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrene sulfonic acid) (PEDOT / PSS).

[0116] Furthermore, the hole injection layer 111 may be formed from an acceptor-like substance. Examples of acceptor-like substances include organic compounds having electron-withdrawing groups (halogen groups, cyano groups, etc.), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexazatriphenylene (abbreviated as HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated as F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene)malononitrile. In particular, compounds in which an electron-withdrawing group is bonded to a condensed aromatic ring having multiple heteroatoms, such as HAT-CN, are thermally stable and preferred. Furthermore, radialene derivatives having an electron-withdrawing group (especially halogen groups such as fluoro groups, cyano groups, etc.) are preferred because they have very high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidenates[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenates[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenates[2,3,4,5,6-pentafluorobenzeneacetonitrile]. In addition to the organic compounds mentioned above, other acceptor materials that can be used include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Acceptor materials can extract electrons from adjacent hole transport layers (or hole transport materials) by applying a voltage between the electrodes.

[0117] Furthermore, the hole injection layer 111 may be formed from a composite material containing the acceptor material and the hole transport material. Various organic compounds can be used as the hole transport material for the composite material, such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.). -6 cm 2 It is preferable that the material has a hole mobility of / Vs or greater. The hole-transporting material 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, anthracene rings, naphthalene rings, etc. are preferred. As the π-electron-rich heteroaromatic ring, a condensed aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, or a thiophene skeleton is preferred, and specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or heteroaromatic ring is further condensed thereon is preferred.

[0118] Materials possessing such hole-transporting properties are more preferably those having one of the following skeletons: carbazole, dibenzofuran, dibenzothiophene, or anthracene. In particular, they may be aromatic amines having substituents including a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. Furthermore, materials possessing these hole-transporting properties are preferred if they are substances having an N,N-bis(4-biphenyl)amino group, as this allows for the fabrication of light-emitting devices with a good lifetime. Examples of materials possessing the hole transport properties described above 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), and 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine). N-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) Name: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-Diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-Diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-Diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-Diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-Diphenyl-4''-(5;2'- Binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenyl Nylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazole-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazole-9-yl)phenyl]tris(1,1'-biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazole-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyl Triphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobio[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis([1,1'-biphenyl]-4-yl)-9,9'-spirobio[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis([1,1'-biphenyl]-4-yl)-9,9'-spirobio[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(1,1'-biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: oFBiSF), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl) Riphenylamine (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-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9'-spirobio[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3- [9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobio-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobio-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobio-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,Examples include 9'-spirobio-9H-fluoren-1-amine.

[0119] Furthermore, other aromatic amine compounds such as N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviated as DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviated as DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviated as DPA3B) can also be used as hole-transporting materials. Additionally, organic compounds can be suitably used in the first hole transport layer 112-1 and the third hole transport layer 112-3.

[0120] Furthermore, it is even more preferable that the hole-transporting material used in the composite material has a relatively deep HOMO level between -5.7 eV and -5.4 eV. Having a relatively deep HOMO level in the hole-transporting material used in the composite material facilitates the injection of holes into the hole transport layer 112 and makes it easier to obtain a light-emitting device with a good lifetime. In addition, having a relatively deep HOMO level in the hole-transporting material used in the composite material moderately suppresses hole induction, resulting in a light-emitting device with an even better lifetime.

[0121] Furthermore, by mixing alkali metal or alkaline earth metal fluoride into the above composite material (preferably with an atomic ratio of fluorine atoms of 20% or more in the layer), the refractive index of the layer can be reduced. This also makes it possible to form a layer with a low refractive index inside the EL layer 103, thereby improving the external quantum efficiency of the light-emitting device.

[0122] By forming the hole injection layer 111, the hole injection performance is improved, and a light-emitting device with a low driving voltage can be obtained.

[0123] Furthermore, among substances with acceptor properties, organic compounds with acceptor properties are easy to use because they are readily deposited and easy to form films.

[0124] The hole transport layer 112 is formed by including a material having hole transport properties. The material having hole transport properties is 1 × 10 -6 cm 2 It is preferable to have a hole mobility of / Vs or greater. The hole transport layer 112 of a light-emitting device according to one aspect of the present invention can be made into a light-emitting device with good characteristics by having the above configuration. For example, it can be made into a light-emitting device with good external quantum efficiency, current efficiency, and blue index or a combination thereof. If the above configuration is not applied, the hole transport layer 112 can be made of a single layer or multiple layers, and the hole transport material can be any of the materials listed as hole transport materials that can be used in the composite material of the hole injection layer described above.

[0125] An electron blocking layer may be provided between the hole transport layer 112 and the light-emitting layer 113. Preferably, the electron blocking layer is made of a material that has hole transport properties and whose LUMO level is 0.25 eV or higher than that of the light-emitting layer 113.

[0126] The light-emitting layer 113 preferably contains a light-emitting substance and a host material. The light-emitting layer 113 may also contain other materials. Furthermore, it may be a laminate of two layers with different compositions.

[0127] The luminescent material may be a fluorescent material, a phosphorescent material, a material exhibiting thermally activated delayed fluorescence (TADF), or any other luminescent material. One aspect of the present invention can be more preferably applied when the luminescent layer 113 is a layer that exhibits fluorescent emission, particularly a layer that exhibits blue fluorescent emission.

[0128] Examples of materials that can be used as fluorescent materials in the light-emitting layer 113 include the following. Other fluorescent materials can also be used.

[0129] 5,6-Bis[4-(10-phenyl-9-antryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-Bis[4'-(10-phenyl-9-antryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-Diphenyl-N,N'-Bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyren-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-carbazole-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-( 10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazole-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-carbazole-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]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPA BPhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazole-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubren, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6 -methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluorantene-3,10-di Amine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinoridine-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]quinoridine-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]quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b Examples include ]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazole-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02). In particular, condensed aromatic diamine compounds, such as pyrenediamine compounds like 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred because they have high hole-trapping properties and excellent luminescence efficiency or reliability.

[0130] When a phosphorescent material is used as the light-emitting material in the light-emitting layer 113, the following are some examples of materials that can be used.

[0131] Organometallic iridium complexes having a 4H-triazole skeleton, such as Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazole-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), Tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), Tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), or Tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), or Tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]). Organometallic iridium complexes having a 1H-triazole skeleton, such as [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), or organometallic iridium complexes having an imidazole skeleton, such as fac-tris[(1-2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpmi)3]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridine]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), or bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’ Iridium(III) tetrakis(1-pyrazolyl) borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’ Iridium(III) picolinate (abbreviation: Firpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinate-N,C 2’ Iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’Examples include organometallic iridium complexes that use phenylpyridine derivatives having electron-withdrawing groups, such as iridium(III) acetylacetonate (abbreviated as FIr(acac)), as ligands. These compounds exhibit blue phosphorescence and have emission peaks in the wavelength range from 440 nm to 520 nm.

[0132] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2- [Ir(mpmppm)2(acac)]) is an organometallic iridium complex having a pyrimidine skeleton, such as [methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), or an organometallic iridium complex having a pyrazine skeleton, such as [Ir(mppr-Me)2(acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyramidinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), or tris(2-phenylpyrimidinato-N,C) 2’ Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinate-N,C) 2’Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinate)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinate)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinate-N,C) 2’ Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C) 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-d3-methyl-8-(2-pyridinyl-κN)benzoflou[2,3-b]pyridinyl-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC] Iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)), [2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzoflou[2,3-b]pyridinyl-7-yl-κC]bis[5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC] Iridium(III) (abbreviation: Ir(5mtpy-d6)2(mbfpy Examples include organometallic iridium complexes with a pyridine skeleton, such as py-iPr-d4), [2-d3-methyl-(2-pyridinyl-κN)benzoflofro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy-d3)), 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)), as well as rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). These compounds primarily exhibit green phosphorescence and have emission peaks in the wavelength range of 500 nm to 600 nm. Organometallic iridium complexes with a pyrimidine skeleton are particularly preferred due to their outstanding reliability and luminescence efficiency.

[0133] Furthermore, organometallic iridium complexes having a pyrimidine skeleton, 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(naphthalene-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), Organometallic iridium complexes having a pyrazine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), or tris(1-phenylisoquinolinato-N,C) 2’ Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C) 2’ Examples include organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as [Ir(piq)2(acac)]), as well as platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviated as PtOEP), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviated as [Eu(DBM)3(Phen)]) and tris[1-(2-tenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviated as [Eu(TTA)3(Phen)]). These compounds exhibit red phosphorescence and have emission peaks in the wavelength range from 600 nm to 700 nm. Furthermore, organometallic iridium complexes with a pyrazine skeleton produce a red emission with good chromaticity.

[0134] In addition to the phosphorescent compounds described above, other known phosphorescent compounds may be selected and used.

[0135] As TADF materials, fullerenes and their derivatives, acridines and their derivatives, eosin derivatives, etc., can be used. Also, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) can be used. Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complexes (SnF2(Proto IX)), mesoporphyrin-tin fluoride complexes (SnF2(Meso IX)), hematoporphyrin-tin fluoride complexes (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complexes (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complexes (SnF2(OEP)), etioporphyrin-tin fluoride complexes (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complexes (PtCl2OEP), as shown in the following structural formulas.

[0136] [ka]

[0137] Furthermore, the following structural formulas represent 2-(biphenyl-4-yl)-4,6-bis(12-phenylindoro[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviated as PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazol (abbreviated as PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as PCCzPTzn), and 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine Heterocyclic compounds having one or both of a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring can also be used, such as (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridine-10-yl)-9H-xanthene-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA). The heterocyclic compound is preferred because it has both a π-electron-excess heteroaromatic ring and a π-electron-deficient heteroaromatic ring, resulting in high electron transport and hole transport properties. Among the skeletons having a π-electron-deficient heteroaromatic ring, the pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, the benzoflopyrimidine skeleton, benzothienopyrimidine skeleton, benzoflopyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptability and are reliable. Furthermore, among the skeletons having a π-electron-excess heteroaromatic ring, the acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable, and therefore it is preferable to have at least one of these skeletons.Furthermore, a dibenzofuran skeleton is preferred as the furan skeleton, and a dibenzothiophene skeleton is preferred as the thiophene skeleton. In addition, as the pyrrole skeleton, indole skeleton, carbazole skeleton, indrocarbazole skeleton, bicarbazole skeleton, and 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole skeleton are particularly preferred. Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because both the electron-donating and electron-accepting properties of the π-electron-rich heteroaromatic ring are strengthened, and the energy difference between the S1 and T1 levels is reduced, thus efficiently obtaining thermally activated delayed fluorescence. In addition, an aromatic ring to which an electron-withdrawing group such as a cyano group is bonded may be used instead of the π-electron-deficient heteroaromatic ring. Furthermore, aromatic amine skeletons, phenazine skeletons, etc., can be used as the π-electron-rich skeleton. Furthermore, as π-electron-deficient skeletons, xanthene skeletons, thioxanthene dioxide skeletons, oxadiazole skeletons, triazole skeletons, imidazole skeletons, anthraquinone skeletons, boron-containing skeletons such as phenylborane or volanthrene, aromatic rings or heteroaromatic rings having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, carbonyl skeletons such as benzophenone, phosphine oxide skeletons, sulfone skeletons, etc., can be used. In this way, π-electron-deficient skeletons and π-electron-excess skeletons can be used instead of at least one of π-electron-deficient heteroaromatic rings and π-electron-excess heteroaromatic rings.

[0138] [ka]

[0139] Furthermore, as the TADF material, a TADF material in which the singlet excited state and the triplet excited state are in thermal equilibrium may be used. Since such a TADF material has a shorter luminescence lifetime (excitation lifetime), it is possible to suppress the decrease in efficiency in the high-brightness region of the light-emitting element. Specifically, materials with the molecular structure shown below can be used.

[0140] [ka]

[0141] TADF materials are materials that have a small difference between the S1 and T1 energy levels and possess the ability to convert energy from triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy with only a small amount of thermal energy (reverse intersystem crossing), and singlet excited states can be efficiently generated. Furthermore, triplet excitation energy can be converted into luminescence.

[0142] Furthermore, an excited complex (also called an exciplex) that forms an excited state with two types of substances has an extremely small difference between the S1 and T1 levels and functions as a TADF material that can convert triplet excitation energy into singlet excitation energy.

[0143] Furthermore, the phosphorescence spectrum observed at low temperatures (e.g., 77K to 10K) can be used as an indicator of the T1 level. For TADF materials, when a tangent is drawn at the short-wavelength tail of the fluorescence spectrum and the energy at the wavelength of the extrapolation is taken as the S1 level, and when a tangent is drawn at the short-wavelength tail of the phosphorescence spectrum and the energy at the wavelength of the extrapolation is taken as the T1 level, it is preferable that the difference between S1 and T1 is 0.3 eV or less, and more preferably 0.2 eV or less.

[0144] Furthermore, when using TADF material as a light-emitting material, it is preferable that the S1 level of the host material is higher than the S1 level of the TADF material. Also, it is preferable that the T1 level of the host material is higher than the T1 level of the TADF material.

[0145] Various carrier transport materials can be used as the host material for the light-emitting layer, such as materials with electron transport properties, materials with hole transport properties, or the TADF material mentioned above.

[0146] As materials having hole transport properties, organic compounds having an amine skeleton, a π-electron-rich heteroaromatic ring skeleton, etc. are preferred. For example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviated as BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as BPAFLP), 4-phenyl -3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBANB), 4,4' These compounds possess aromatic amine skeletons such as -di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9'-spirobio[9H-fluoren]-2-amine (abbreviation: PCBASF). Compounds such as 1,3-bis(N-carbazolyl)benzene (abbreviated as mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviated as CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as PCCP), or compounds having a carbazole skeleton, or 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviated as DBT3P-II), 2,Examples include compounds having a thiophene skeleton such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviated as DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV), or compounds having a furan skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviated as DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviated as mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton or a carbazole skeleton are preferred because they have good reliability, high hole transportability, and contribute to reducing the driving voltage. In addition, organic compounds listed as examples of hole transportable materials in the hole transport layer 112 can also be used. ,

[0147] Preferred electron-transporting materials include metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviated as BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviated as BAlq), bis(8-quinolinolato)zinc(II) (abbreviated as Znq), bis[2-(2-benzoxazollyl)phenolato]zinc(II) (abbreviated as ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviated as ZnBTZ), or organic compounds having a π-electron-deficient heteroaromatic ring. Examples of organic compounds having a π-electron-deficient heteroaromatic ring include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviated as TAZ), and 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole [2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-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 Organic compounds with an azole skeleton, such as azole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazole-2-yl)stilbene (abbreviation: BzOs), 3,5-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), and vasophenanthroline (abbreviation: Bp Organic compounds containing heteroaromatic rings with a pyridine skeleton, such as hen), vasocuproin (abbreviated as BCP), 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBphen), 2,2-(1,3-phenylene)bis[9-phenyl-1,10-phenanthroline] (abbreviated as mPPhen2P), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,[h]Quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]Quinoxaline (abbreviation: 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), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]flo[2,3-b]pyrazine (abbreviation: 9mDBtBPNf pr), 9-[(3'-dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]flo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazole-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[pyrimidine-4, 6-Diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzoflo[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzoflo[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzoflo[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(1,1'-biphenyl-3-yl)]naphtho[1',2':4,5]flo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalene)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzoflo[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthalene-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazole-9-yl)phenyl] Organic compounds having a diazine skeleton, such as 2-[(1,1'-biphenyl)-4-yl]-2-phenyl-6-(1,1'-biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazoline-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), 2-[(1,1'-biphenyl)-4-yl]-4-phenyl-6-[9,9'-spirobio(9H-fluorene)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), and 2-{3-[3-(ben Zo[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-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-Diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-7,7- Dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris(3'-(pyridine-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyri) [Dinyl)-5-(9-phenantrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-(4-[1,1'-diphenyl]-4-yl-6-phenyl-1,3,5-triazine-2-yl)-11,12-dihydro-12-phenyl-indoro[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylene-2-yl)-1,1'-bi Phenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 9-[4-(4,6-diphenyl-1,3,5-triazine-2-yl)-2-dibenzothiophenyl]-2-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-[1,1'-biphenyl]-3-yl-4-phenyl-6-(8-[1,1':4',1''-terphenyl]-4-yl-1-dibenzofuranyl)-1,3,Examples include organic compounds containing heteroaromatic rings having a triazine skeleton, such as 5-triazine (abbreviation: mBP-TPDBfTzn). Among those mentioned above, organic compounds containing heteroaromatic rings having a diazine skeleton, or heteroaromatic rings having a pyridine skeleton, or heteroaromatic rings having a triazine skeleton are preferred due to their good reliability. In particular, organic compounds containing heteroaromatic rings having a diazine (pyrimidine or pyrazine) skeleton, or heteroaromatic rings having a triazine skeleton, exhibit high electron transport properties and contribute to reducing the driving voltage.

[0148] The TADF materials listed above can be used as host materials. When a TADF material is used as a host material, the triplet excitation energy generated by the TADF material is converted into singlet excitation energy through reverse intersystem crossing, and this energy is then transferred to the light-emitting material, thereby increasing the luminescence efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor.

[0149] This is particularly effective when the light-emitting material is a fluorescent material. Furthermore, in order to obtain high luminescence efficiency, it is preferable that the S1 level of the TADF material is higher than that of the fluorescent material. Also, it is preferable that the T1 level of the TADF material is higher than that of the fluorescent material. Therefore, it is preferable that the T1 level of the TADF material is higher than that of the fluorescent material.

[0150] Furthermore, it is preferable to use a TADF material that exhibits emission at a wavelength that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material. This is preferable because it allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient emission.

[0151] Furthermore, for singlet excitation energy to be efficiently generated from triplet excitation energy by reverse intersystem crossing, it is preferable that carrier recombination occurs in the TADF material. It is also preferable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent material. To achieve this, it is preferable that the fluorescent material has protecting groups around the luminescent phosphodiocyte (the skeleton that causes luminescence). Preferred protecting groups are substituents without π bonds, and saturated hydrocarbons are preferred. Specifically, examples include alkyl groups having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3 to 10 carbon atoms, and trialkylsilyl groups having 3 to 10 carbon atoms. It is even more preferable to have multiple protecting groups. Substituents without π bonds have poor carrier transport function, and therefore can increase the distance between the TADF material and the luminescent phosphodiocyte of the fluorescent material with little effect on carrier transport and carrier recombination. Here, the luminescent phosphodiocyte refers to the atomic group (skeleton) that causes luminescence in the fluorescent material. The luminescent phosphodiosity preferably has a skeleton containing π bonds, preferably contains an aromatic ring, and preferably has a condensed aromatic ring or a condensed heteroaromatic ring. Examples of condensed aromatic rings or condensed heteroaromatic rings include phenanthrene skeletons, stilbene skeletons, acridone skeletons, phenoxazine skeletons, and phenothiazine skeletons. Fluorescent materials having naphthalene, anthracene, fluorene, chrysene, triphenylene, tetracene, pyrene, perylene, coumarin, quinacridone, or naphthobisbenzofuran skeletons are particularly preferred due to their high fluorescence quantum yield.

[0152] When using a fluorescent material as the light-emitting material, a material having an anthracene skeleton is preferred as the host material. Using a material having an anthracene skeleton as the host material for a fluorescent material makes it possible to realize a light-emitting layer with good luminescence efficiency and durability. Among the materials having an anthracene skeleton to be used as the host material, materials having a diphenylanthracene skeleton, and especially a 9,10-diphenylanthracene skeleton, are preferred because they are chemically stable. Furthermore, while a carbazole skeleton is preferred as the host material because it improves hole injection and transport, a benzocarbazole skeleton, in which a benzene ring is further condensed into carbazole, is even more preferred because the HOMO is about 0.1 eV shallower than carbazole, making it easier for holes to enter. In particular, a dibenzocarbazole skeleton is preferred as the HOMO is about 0.1 eV shallower than carbazole, making it easier for holes to enter, and it also has excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or dibenzocarbazole skeleton). Furthermore, from the viewpoint of hole injection and transport properties, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton.Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviated as PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated as PCPN), 9-[4-(10-phenyl-9-antracenyl)phenyl]-9H-carbazole (abbreviated as CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviated as cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviated as 2mBnfPPA), and 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-phenylanthracene-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)-benzo[b Examples include naphtho[2,3-d]furan (abbreviated as Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviated as βN-mβNPAnth), and 1-[4-(10-[1,1'-biphenyl]-4-yl-9-anthracenyl)phenyl]-2-ethyl-1H-benzimidazole (abbreviated as EtBImPBPhA). In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA exhibit very good properties and are therefore preferred choices.

[0153] Note that the host material may be a material obtained by mixing a plurality of substances. When using a mixed host material, it is preferable to mix a material having electron transporting properties and a material having hole transporting properties. By mixing a material having electron transporting properties and a material having hole transporting properties, the transporting properties of the light emitting layer 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole transporting properties to the material having electron transporting properties may be Hole transporting material: Electron transporting material = 1:19 to 19:1.

[0154] Note that, as a part of the above mixed material, a phosphorescent light emitting substance can be used. The phosphorescent light emitting substance can be used as an energy donor that supplies excitation energy to the fluorescent light emitting substance when using the fluorescent light emitting substance as the light emitting substance.

[0155] Also, an exciplex may be formed between these mixed materials. By selecting a combination that forms an exciplex that emits light overlapping the wavelength of the absorption band on the lowest energy side of the light emitting substance, energy transfer becomes smooth and efficient light emission can be obtained, which is preferable. Also, since the driving voltage is reduced by using this configuration, it is preferable.

[0156] Note that at least one of the materials forming the exciplex may be a phosphorescent light emitting substance. By doing so, triplet excitation energy can be efficiently converted into singlet excitation energy by reverse intersystem crossing.

[0157] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of the material having hole transporting properties is equal to or higher than the HOMO level of the material having electron transporting properties. Also, it is preferable that the LUMO level of the material having hole transporting properties is equal to or higher than the LUMO level of the material having electron transporting properties. Note that the LUMO level and HOMO level of the material can be derived from the electrochemical characteristics (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV) measurement.

[0158] The formation of excited complexes can be confirmed, for example, by comparing the emission spectra of a hole-transporting material, an electron-transporting material, and a mixed film made by mixing these materials, and observing that the emission spectrum of the mixed film shifts to a longer wavelength than the emission spectra of each individual material (or has a new peak on the longer wavelength side). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a hole-transporting material, the transient PL of an electron-transporting material, and the transient PL of a mixed film made by mixing these materials, and observing differences in the transient response, such as the transient PL lifetime of the mixed film having a longer lifetime component or a larger proportion of the delayed component than the transient PL lifetime of each individual material. Furthermore, the transient PL mentioned above can be replaced with transient electroluminescence (EL). That is, the formation of excited complexes can also be confirmed by comparing the transient EL of a hole-transporting material, the transient EL of an electron-transporting material, and the transient EL of a mixed film made by mixing these materials, and observing the differences in the transient response.

[0159] The electron transport layer 114 is a layer containing an electron-transporting material. The electron-transporting material has an electron mobility of 1 × 10⁻¹⁰ at an electric field strength [V / cm] square root of 600. -6 cm 2 A substance having an electron mobility of 1 / Vs or higher is preferred. However, any substance that has higher electron transport than holes can be used. As the above organic compound, an organic compound having a π-electron-deficient heteroaromatic ring is preferred. As an organic compound having a π-electron-deficient heteroaromatic ring, it is preferable that it be any or more of the following: an organic compound containing a heteroaromatic ring having a polyazole skeleton, an organic compound containing a heteroaromatic ring having a pyridine skeleton, an organic compound containing a heteroaromatic ring having a diazine skeleton, and an organic compound containing a heteroaromatic ring having a triazine skeleton.

[0160] Examples of electron-transporting materials that can be used in the above electron transport layer include, specifically, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviated as TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviated as OXD-7), and 9-[4-(5-phenyl-1,3,4-oxadiazole-2- Organic compounds having an azole skeleton such as 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-methylbenzoxazole-2-yl)stilbene (abbreviation: BzOs), 3,5-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviation: Organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 35DCzPPy, 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), vasophenanthroline (abbreviation: Bphen), vasocuproin (abbreviation: BCP), 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), and 2,2-(1,3-phenylene)bis[9-phenyl-1,10-phenanthroline] (abbreviation: mPPhen2P), and 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo Nzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazole-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-Diphenyl-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]flo[2,3-b]pyrazine (abbreviation: 9mDBtB PNfpr), 9-[(3'-dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]flo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazole-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[pyrimidine-4, 6-Diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzoflo[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzoflo[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzoflo[3,2- d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(1,1'-biphenyl-3-yl)]naphtho[1',2':4,5]flo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalene)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzoflo[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthalene-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-bi Organic compounds having a diazine skeleton, such as su(9H-carbazole-9-yl)phenyl]-2-phenyl-6-(1,1'-biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazole-2-yl)quinazoline-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), and 2-[(1,1'-biphenyl)-4-yl]-4-phenyl-6-[9,9'-spirobio(9H-fluorene)-2-yl]-1,3,5-triazine (abbreviation: BP-S FTzn), 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-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-to Liazin (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazin (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b] Carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris(3’-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-(4-[1,1’-diphenyl]-4-yl-6-phenyl-1,3,5-triazine-2-yl)-11,12-dihydro-12-phenyl-indolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3’-(triphenylene-2-yl)-1,1’-biphenyl-3-yl]-4,6-diphenyl’1,3,5-triazine (abbreviation: mTpBPTzn), 9-[4-(4,6-diphenyl-1,3,5-triazine-2-yl)-2-dibenzothiophenyl]-2-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-[1,1’-biphenyl]-3-yl-4-phenyl-6-(8-[1,1’:4’,1’’-terphenyl]-4-yl-1-dibenzofuranyl)-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), and other organic compounds having a triazine skeleton can be mentioned. Among those described above, organic compounds containing a heteroaromatic ring having a diazine skeleton or an organic compound containing a heteroaromatic ring having a pyridine skeleton, and an organic compound containing a heteroaromatic ring having a triazine skeleton are preferable because of their good reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transportability and contribute to reducing the driving voltage.,

[0161] Also, by using a material having low refractive index and electron transportability in the electron transport layer 114, it becomes possible to obtain a light-emitting device with even better characteristics.

[0162] As an organic compound having low refractive index and electron transport properties that can be used in an electron transport layer, it is preferable to have an organic compound that has at least one six-membered heteroaromatic ring containing one to three nitrogen atoms, and has multiple aromatic hydrocarbon rings with 6 to 14 carbon atoms forming the ring, and of the multiple aromatic hydrocarbon rings at least two are benzene rings, and has multiple hydrocarbon groups that form bonds in sp3 hybrid orbitals.

[0163] Furthermore, it is preferable that the ratio of the total number of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the molecule of such an organic compound is 10% to 60%, and more preferably 10% to 50%. Alternatively, such an organic compound may be 1 It is preferable that the integral value of signals less than 4 ppm in the measurement of the organic compound by 1H-NMR is at least half the integral value of signals of 4 ppm or more.

[0164] Preferably, the molecular weight of the electron-transporting organic compound is between 500 and 2000. Furthermore, it is preferable that the hydrocarbon groups forming bonds in all sp3 hybrid orbitals of the organic compound are bonded to an aromatic hydrocarbon ring having 6 to 14 carbon atoms that forms the ring, and that the LUMO of the organic compound is not distributed in that aromatic hydrocarbon ring.

[0165] The following general formula (G e1 1) or (G e1 The organic compound represented in 1-1) is preferred.

[0166] [ka]

[0167] In the formula, A represents a six-membered heteroaromatic ring containing 1 to 3 nitrogen atoms, and is preferably a pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, or triazine ring.

[0168] Also, R 200This represents hydrogen, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or a substituent represented by formula (G1-1).

[0169] R 201 ~R 215 At least one of the members is a substituted phenyl group, and the others each independently represent one of the following: hydrogen, a C1 to C6 alkyl group, a C3 to C10 alicyclic group, a substituted or unsubstituted C6 to C14 aromatic hydrocarbon group forming a ring, or a substituted or unsubstituted pyridyl group. 201 , R 203 , R 205 , R 206 , R 208 , R 210 , R 211 , R 213 and R 215 It is preferable that is hydrogen. The phenyl group having the substituent has one or two substituents, each of which is independently one of the following: an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 14 carbon atoms that forms a substituted or unsubstituted ring.

[0170] Note that the above general formula (G e1 The organic compound represented in 1) has multiple hydrocarbon groups selected from alkyl groups having 1 to 6 carbon atoms and alicyclic groups having 3 to 10 carbon atoms, and the proportion of the total number of carbon atoms that form bonds in sp3 hybrid orbitals relative to the total number of carbon atoms in the molecule is between 10% and 60%.

[0171] Furthermore, the following general formula (G e1 The organic compound represented in 2) is preferred.

[0172] [ka]

[0173] In the formula, Q 1 ~Q 3 Of these, 2 or 3 represent N, and Q 1 ~Q3 When two of them are N, the remaining one represents CH.

[0174] Also, R 201 to R 215 At least one of them is a phenyl group having a substituent, and the others are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 14 carbon atoms forming a substituted or unsubstituted ring, or a substituted or unsubstituted pyridyl group. Note that R 201 、R 203 、R 205 、R 206 、R 208 、R 210 、R 211 、R 213 and R 215 are preferably hydrogen. The phenyl group having a substituent has one or two substituents, and each of the substituents is independently an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 14 carbon atoms forming a substituted or unsubstituted ring.

[0175] Note that the organic compound represented by the above general formula (G e1 2) has a plurality of hydrocarbon groups selected from an alkyl group having 1 to 6 carbon atoms and an alicyclic group having 3 to 10 carbon atoms, and the ratio of the total number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in the molecule is preferably 10% or more and 60% or less.

[0176] Also, in the organic compound represented by the above general formula (G e1 1) or (G e1 2), the phenyl group having a substituent is preferably a group represented by the following formula (G e1 1-2).

[0177]

Chemical formula

[0178] In the formula, α represents a substituted or unsubstituted phenylene group, and is preferably a meta-substituted phenylene group. Furthermore, if the meta-substituted phenylene group has one substituent, it is preferable that this substituent is also meta-substituted. The substituent is preferably a C1 to C6 alkyl group or a C3 to C10 alicyclic group, more preferably a C1 to C6 alkyl group, and even more preferably a t-butyl group.

[0179] R 220 This represents an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 14 carbon atoms that forms a substituted or unsubstituted ring.

[0180] Also, j and n represent 1 or 2. Note that if j is 2, the multiple αs may be the same or different. Also, if k is 2, multiple R 220 These can be the same or different. Note that R 220 The substituent is preferably a phenyl group, and more preferably a phenyl group having a C1 to C6 alkyl group or a C3 to C10 alicyclic group at one or both of its two meta positions. More preferably the substituents on one or both of the two meta positions of the phenyl group are C1 to C6 alkyl groups, and even more preferably t-butyl groups.

[0181] Organic compounds possessing the electron-transporting properties described above are those whose ordinary refractive index in the blue light emission region (455 nm to 465 nm) is 1.50 to 1.75, or whose ordinary refractive index at 633 nm light, which is commonly used for measuring refractive index, is 1.45 to 1.70, and which also exhibit good electron-transporting properties.

[0182] Furthermore, when using the above-mentioned electron-transporting organic compound in the electron transport layer 114, it is preferable that the electron transport layer 114 further contains an alkali metal or alkaline earth metal metal complex. Heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, and heterocyclic compounds having a pyridine skeleton are preferred from the viewpoint of drive life because the energy of the excited complex formed with an alkali metal organometallic complex is easily stabilized (the emission wavelength of the excited complex is easily lengthened). In particular, heterocyclic compounds having a diazine skeleton or heterocyclic compounds having a triazine skeleton are suitable for energy stabilization of the excited complex because the LUMO level is deep.

[0183] Furthermore, the alkali metal organometallic complex is preferably a sodium or lithium metal complex. Alternatively, the alkali metal organometallic complex is preferably a ligand having a quinolinol skeleton. More preferably, the alkali metal organometallic complex is a lithium complex or a derivative thereof containing an 8-quinolinolate structure. As a derivative of the lithium complex containing an 8-quinolinolate structure, a lithium complex containing an 8-quinolinolate structure having an alkyl group is preferred, and it is particularly preferred to have a methyl group.

[0184] 8-Quinolinolatolithium having an alkyl group can be used to form metal complexes with a low refractive index. Specifically, in a thin film state, the paraphotometric refractive index for light with wavelengths in the range of 455 nm to 465 nm can be 1.45 to 1.70, and the paraphotometric refractive index for light with a wavelength of 633 nm can be 1.40 to 1.65.

[0185] Specifically, examples of the above-mentioned metal complexes include 8-hydroxyquinolinato-lithium (abbreviated as Liq) and 8-hydroxyquinolinato-sodium (abbreviated as Naq). In particular, monovalent metal ion complexes are preferred, with lithium complexes being preferred, and Liq being more preferred. When an 8-hydroxyquinolinato structure is included, it is also preferable to use its methyl-substituted derivatives (e.g., 2-methyl-substituted derivatives, 5-methyl-substituted derivatives, or 6-methyl-substituted derivatives). In particular, using an alkali metal complex having an 8-quinolinolato structure with an alkyl group at the 6-position has the effect of lowering the driving voltage of the light-emitting device.

[0186] Furthermore, the electron transport layer 114 has an electron mobility of 1 × 10⁻¹⁴ at an electric field strength [V / cm] square root of 600. -7 cm 2 / Vs or more 5×10 -5 cm 2 It is preferable that the value is less than or equal to / Vs. By reducing the electron transport properties in the electron transport layer 114, the amount of electrons injected into the light-emitting layer can be controlled, preventing the light-emitting layer from becoming electron-excessive. This configuration is particularly preferable because it results in a good lifetime when the hole injection layer is formed as a composite material and the HOMO level of the material having hole transport properties in the composite material is a relatively deep HOMO level between -5.7eV and -5.4eV. In this case, it is preferable that the HOMO level of the material having electron transport properties is -6.0eV or higher.

[0187] Between the electron transport layer 114 and the second electrode 102, an electron injection layer 115 may be provided, which contains an alkali metal or alkaline earth metal, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), or 8-hydroxyquinolinatolithium (abbreviated as Liq), or a compound or complex thereof. The electron injection layer 115 may be a layer made of an electron-transporting material containing an alkali metal or alkaline earth metal or a compound thereof, or an electride may be used. Examples of electrides include a material obtained by adding electrons to a mixed oxide of calcium and aluminum at a high concentration.

[0188] Furthermore, as the electron injection layer 115, it is also possible to use a layer containing an electron-transporting substance (preferably an organic compound having a bipyridine skeleton) with an alkali metal or alkaline earth metal fluoride at a concentration above that which results in a microcrystalline state (50 wt% or more). Since this layer has a low refractive index, it is possible to provide a light-emitting device with better external quantum efficiency.

[0189] Alternatively, a charge generation layer 116 may be provided instead of the electron injection layer 115 in Figure 1(A) (Figure 1(B)). The charge generation layer 116 is a layer that can inject holes into the layer in contact with the cathode side and electrons into the layer in contact with the anode side by applying a potential. The charge generation layer 116 includes at least a P-type layer 117. The P-type layer 117 is preferably formed using a composite material listed above as a material that can constitute the hole injection layer 111. The P-type layer 117 may also be formed by laminating a film containing the acceptor material and a film containing the hole transport material as materials that constitute the composite material. By applying a potential to the P-type layer 117, electrons are injected into the electron transport layer 114 and holes are injected into the second electrode 102, which is the cathode, and the light-emitting device operates.

[0190] Furthermore, it is preferable that the charge generation layer 116 includes, in addition to the P-type layer 117, one or both of the electron relay layer 118 and the electron injection buffer layer 119.

[0191] The electron relay layer 118 contains at least an electron-transporting material and has the function of preventing interaction between the electron injection buffer layer 119 and the P-type layer 117, thereby smoothly transferring electrons. The LUMO level of the electron-transporting material contained in the electron relay layer 118 is preferably between the LUMO level of the acceptor material in the P-type layer 117 and the LUMO level of the material contained in the layer in contact with the charge generation layer 116 in the electron transport layer 114. The specific energy level of the LUMO level of the electron-transporting material used in the electron relay layer 118 is preferably -5.0 eV or higher, more preferably -5.0 eV or higher and -3.0 eV or lower. It is preferable to use a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand as the electron-transporting material used in the electron relay layer 118.

[0192] The electron injection buffer layer 119 can use materials with high electron injection potential, such as alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate or cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)).

[0193] Furthermore, if the electron injection buffer layer 119 is formed by including an electron-transporting substance and a donor substance, the donor substance may include alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate or cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)), as well as organic compounds such as tetratianaphthalene (abbreviated as TTN), nickerosene, and decamethylnickerosene.

[0194] Furthermore, the electron-transporting material can be formed using the same material as that used to constitute the electron transport layer 114 described earlier. Since this material is an organic compound with a low refractive index, using it in the electron injection buffer layer 119 makes it possible to obtain a light-emitting device with good external quantum efficiency.

[0195] As the material forming the second electrode 102, metals, alloys, electrically conductive compounds, and mixtures thereof with a small work function (specifically, 3.8 eV or less) can be used. Specific examples of such cathode materials include alkali metals such as lithium (Li) or cesium (Cs), elements belonging to Group 1 or 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), and alloys containing these (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these. However, by providing an electron injection layer between the second electrode 102 and the electron transport layer, various conductive materials such as Al, Ag, ITO, silicon, or indium oxide-tin oxide containing silicon oxide can be used as the second electrode 102, regardless of the magnitude of their work functions.

[0196] Furthermore, if the second electrode 102 is formed from a material that is transparent to visible light, it can be made into a light-emitting device that emits light from the cathode side, as shown in Figure 1(D). If the first electrode 101 is fabricated on the substrate side, this light-emitting device can be made into a so-called top-emission type light-emitting device.

[0197] These conductive materials can be formed using dry methods such as vacuum deposition or sputtering, inkjet printing, or spin coating. Alternatively, they may be formed using a wet method with a sol-gel process, or using a metal paste.

[0198] Furthermore, various methods can be used to form the EL layer 103, regardless of whether they are dry or wet methods. For example, vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, or spin coating may be used.

[0199] Furthermore, each electrode or layer described above may be formed using different film deposition methods.

[0200] The configuration of the layer provided between the first electrode 101 and the second electrode 102 is not limited to those described above. However, a configuration is preferred in which a light-emitting region is provided at a location away from the first electrode 101 and the second electrode 102 where holes and electrons recombine, in order to suppress quenching that occurs when the light-emitting region is in close proximity to the electrode or the metal used in the carrier injection layer.

[0201] Furthermore, the hole transport layer or electron transport layer in contact with the light-emitting layer 113, and especially the carrier transport layer near the recombination region in the light-emitting layer 113, is preferably made of a material whose band gap is larger than that of the light-emitting material constituting the light-emitting layer or the light-emitting material contained in the light-emitting layer, in order to suppress energy transfer from excitons generated in the light-emitting layer.

[0202] Next, we will describe an embodiment of a light-emitting device (also called a stacked element or tandem element) with a configuration in which multiple light-emitting units are stacked. This light-emitting device has multiple light-emitting units between the anode and the cathode. One light-emitting unit has a configuration almost identical to the EL layer 103 shown in Figure 1(A). In other words, a tandem element is a light-emitting device having multiple light-emitting units, and the light-emitting device shown in Figure 1(A) or Figure 1(B) can be said to be a light-emitting device having one light-emitting unit.

[0203] In a tandem element, a first light-emitting unit and a second light-emitting unit are stacked between the anode and the cathode, and a charge generation layer is provided between the first and second light-emitting units. The anode and cathode correspond to the first electrode 101 and the second electrode 102 in Figure 1(A), respectively, and the same components as described in the explanation of Figure 1(A) can be applied. Furthermore, the first and second light-emitting units may have the same configuration or different configurations.

[0204] In a tandem element, the charge generation layer has the function of injecting electrons into one light-emitting unit and holes into the other light-emitting unit when a voltage is applied to the anode and cathode. That is, when a voltage is applied such that the potential of the anode is higher than the potential of the cathode, the charge generation layer should inject electrons into the first light-emitting unit and holes into the second light-emitting unit.

[0205] The charge generation layer is preferably formed with the same configuration as the charge generation layer 116 described in Figure 1(B). The composite material of organic compounds and metal oxides has excellent carrier implantation and carrier transport properties, enabling low-voltage and low-current operation. If the anode side of the light-emitting unit is in contact with the charge generation layer, the charge generation layer can also act as a hole injection layer for the light-emitting unit, so the light-emitting unit does not need to have a hole injection layer.

[0206] Furthermore, when an electron injection buffer layer 119 is provided in the charge generation layer of a tandem element, the electron injection buffer layer 119 plays the role of an electron injection layer in the anode-side light-emitting unit, so it is not necessarily required to form an electron injection layer in the anode-side light-emitting unit.

[0207] The above describes a tandem element having two light-emitting units, but the same principles can be applied to tandem elements with three or more light-emitting units stacked on top of each other. By arranging multiple light-emitting units separated between a pair of electrodes by a charge generation layer, it is possible to achieve high-brightness light emission while maintaining a low current density, and to realize an element with a longer lifespan. Furthermore, it is possible to realize a light-emitting device that can be driven at a low voltage and consumes little power.

[0208] Furthermore, by making the light-emitting colors of each light-emitting unit different, it is possible to obtain a desired color of light emission from the entire light-emitting device. For example, in a light-emitting device having two light-emitting units, it is possible to obtain a light-emitting device that emits white light as a whole by obtaining red and green light-emitting colors from the first light-emitting unit and blue light-emitting color from the second light-emitting unit.

[0209] Furthermore, each layer or electrode, such as the EL layer 103, the first light-emitting unit, the second light-emitting unit, and the charge generation layer, can be formed using methods such as vapor deposition (including vacuum deposition), droplet ejection (also known as inkjet printing), coating, and gravure printing. They may also contain low-molecular-weight materials, medium-molecular-weight materials (including oligomers and dendrimers), or polymer materials.

[0210] Furthermore, this embodiment can be freely combined with other embodiments.

[0211] (Embodiment 2) This embodiment describes a light-emitting device using the light-emitting device described in Embodiment 1.

[0212] In this embodiment, an active matrix type light-emitting device fabricated using the light-emitting device described in Embodiment 1 will be described with reference to Figures 2(A) and 2(B). Figure 2(A) is a top view showing the light-emitting device, and Figure 2(B) is a cross-sectional view taken along the dashed lines AB and CD shown in Figure 2(A). This light-emitting device includes a drive circuit section (source line drive circuit) 601, a pixel section 602, and a drive circuit section (gate line drive circuit) 603, all indicated by dotted lines, to control the light emission of the light-emitting device. Furthermore, 604 is a sealing substrate, and 605 is a sealing material, with the area enclosed by the sealing material 605 being a space 607.

[0213] The routing wiring 608 is for transmitting signals input to the source line drive circuit 601 and the gate line drive circuit 603, and receives video signals, clock signals, start signals, reset signals, etc. from the FPC (flexible printed circuit) 609, which serves as an external input terminal. Although only the FPC is shown in this illustration, a printed circuit board (PWB) may be attached to this FPC. In this specification, the light-emitting device includes not only the light-emitting device itself, but also the state in which the FPC or PWB is attached to it.

[0214] Next, the cross-sectional structure will be explained using Figure 2(B). A drive circuit section and a pixel section are formed on the element substrate 610, and here, the source line drive circuit 601, which is the drive circuit section, and one pixel in the pixel section 602 are shown.

[0215] The element substrate 610 may be manufactured using a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or other materials, as well as a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, or acrylic resin.

[0216] The structure of the transistor used in the pixel or driving circuit is not particularly limited. For example, it may be an inverse staggered transistor or a staggered transistor. It may also be a top-gate or bottom-gate transistor. The semiconductor material used for the transistor is not particularly limited; for example, silicon, germanium, silicon carbide, gallium nitride, etc., can be used. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In-Ga-Zn metal oxide, may be used.

[0217] The crystallinity of the semiconductor material used in the transistor is not particularly limited; amorphous semiconductors, crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or semiconductors having a crystalline region in part) may be used. Using a crystalline semiconductor is preferable because it can suppress the degradation of transistor characteristics.

[0218] Here, it is preferable to use oxide semiconductors for semiconductor devices such as transistors used in the pixels or driving circuits described above, as well as transistors used in touch sensors and the like, which will be described later. In particular, it is preferable to use oxide semiconductors with a wider bandgap than silicon. By using oxide semiconductors with a wider bandgap than silicon, the current in the off state of the transistor can be reduced.

[0219] The above oxide semiconductor preferably contains at least indium (In) or zinc (Zn). More preferably, it is an oxide semiconductor containing an oxide represented as an In-M-Zn oxide (where M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0220] In particular, it is preferable to use an oxide semiconductor film as the semiconductor layer, which has multiple crystalline portions, the c-axis of which is oriented perpendicular to the surface on which the semiconductor layer is formed or to the upper surface of the semiconductor layer, and which does not have grain boundaries between adjacent crystalline portions.

[0221] By using such materials as semiconductor layers, fluctuations in electrical properties can be suppressed, enabling the realization of highly reliable transistors.

[0222] Furthermore, due to its low off-current, the transistor having the aforementioned semiconductor layer can retain the charge stored in the capacitor via the transistor for a long period of time. By applying such transistors to pixels, it becomes possible to maintain the gradation of the image displayed in each display area while simultaneously stopping the drive circuit. As a result, electronic devices with extremely reduced power consumption can be realized.

[0223] It is preferable to provide an undercoat to stabilize the characteristics of the transistor. As the undercoat, an inorganic insulating film such as a silicon oxide film, silicon nitride film, silicon oxynitride film, or silicon nitride film can be used and fabricated as a single layer or in layers. The undercoat can be formed using sputtering, CVD (Chemical Vapor Deposition) (plasma CVD, thermal CVD, MOCVD (Metal Organic CVD), etc.), ALD (Atomic Layer Deposition), coating, printing, etc. Note that the undercoat may be omitted if not necessary.

[0224] Note that FET623 is one of the transistors formed in the drive circuit section 601. The drive circuit can be formed using various CMOS, PMOS, or NMOS circuits. In this embodiment, a driver-integrated type with the drive circuit formed on the substrate is shown, but this is not necessarily required, and the drive circuit can be formed externally instead of on the substrate.

[0225] Furthermore, although the pixel section 602 is formed by a plurality of pixels including a switching FET 611 and a current control FET 612 and a first electrode 613 electrically connected to its drain, it is not limited to this, and the pixel section may be a combination of three or more FETs and a capacitive element.

[0226] Furthermore, an insulator 614 is formed to cover the end of the first electrode 613. This can be formed by using a positive-type photosensitive acrylic resin film.

[0227] Furthermore, in order to ensure good coverage of the EL layer and the like that will be formed later, a curved surface with curvature is formed at the upper or lower end of the insulator 614. For example, when a positive-type photosensitive acrylic resin is used as the material for the insulator 614, it is preferable to have a curved surface with a radius of curvature (0.2 μm to 3 μm) only at the upper end of the insulator 614. In addition, either a negative-type photosensitive resin or a positive-type photosensitive resin can be used as the insulator 614.

[0228] An EL layer 616 and a second electrode 617 are formed on the first electrode 613, respectively. Here, the first electrode 613 functions as an anode. As a material that can be used as an anode, it is desirable to use a material with a large work function. For example, in addition to single-layer films such as ITO film, silicon-containing indium tin oxide film, indium oxide film containing 2-20 wt% zinc oxide, titanium nitride film, chromium film, tungsten film, Zn film, and Pt film, lamination with a silver-based film, lamination with a titanium nitride film and an aluminum-based film, and a three-layer structure of titanium nitride film, aluminum-based film and titanium nitride film can be used. Furthermore, a laminated structure has low resistance as a wiring, good ohmic contact can be obtained, and it can function as an anode.

[0229] Furthermore, the EL layer 616 is formed by various methods such as deposition using a deposition mask, inkjet method, and spin coating method. The EL layer 616 includes the configuration described in Embodiment 1.

[0230] Furthermore, it is preferable to use a material with a small work function (such as Al, Mg, Li, Ca, or alloys or compounds thereof (MgAg, MgIn, AlLi, etc.)) as the material used for the second electrode 617 formed on the EL layer 616. When light generated in the EL layer 616 is transmitted through the second electrode 617, it is preferable to use a laminate of a thin metal or alloy film with a thin film thickness and a transparent conductive film (such as ITO, indium oxide containing 2-20 wt% zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) as the second electrode 617.

[0231] A light-emitting device is formed by the first electrode 613, the EL layer 616, and the second electrode 617. This light-emitting device is the light-emitting device described in Embodiment 1. Although the pixel portion is made up of multiple light-emitting devices, in the light-emitting device of this embodiment, both the light-emitting device described in Embodiment 1 and light-emitting devices having other configurations may be mixed. In this case, in the light-emitting device of one aspect of the present invention, a common hole transport layer can be used between light-emitting devices that emit light of different wavelengths, making it possible to create a light-emitting device with a simple manufacturing process and cost advantages.

[0232] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, the light-emitting device 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. The space 607 is filled with a filler material, which may be an inert gas (such as nitrogen or argon) or a sealing material. A recess is formed in the sealing substrate, and a desiccant is placed therein to suppress deterioration due to the effects of moisture, which is a preferred configuration.

[0233] Furthermore, it is preferable to use epoxy resin or glass frit for the sealing material 605. It is also desirable that these materials are as impermeable to moisture and oxygen as possible. In addition to glass substrates or quartz substrates, plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, or acrylic resin can be used as the material for the sealing substrate 604.

[0234] Although not shown in Figures 2(A) and 2(B), a protective film may be provided on the cathode. The protective film may be formed of an organic resin film or an inorganic insulating film. Alternatively, the protective film may be formed to cover the exposed portion of the sealing material 605. Furthermore, the protective film can be provided to cover the surface and sides of the pair of substrates, the sealing layer, the insulating layer, and other exposed sides.

[0235] The protective film can be made of a material that is impermeable to impurities such as water. Therefore, it is possible to effectively suppress the diffusion of impurities such as water from the outside to the inside.

[0236] Materials that constitute the protective film can include oxides, nitrides, fluorides, sulfides, ternary compounds, metals, or polymers. For example, materials containing aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide, or indium oxide, or materials containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, or gallium nitride, nitrides containing titanium and aluminum, oxides containing titanium and aluminum, oxides containing aluminum and zinc, sulfides containing manganese and zinc, sulfides containing cerium and strontium, oxides containing erbium and aluminum, oxides containing yttrium and zirconium, etc.

[0237] It is preferable to form the protective film using a film deposition method that provides good step coverage. One such method is atomic layer deposition (ALD). It is preferable to use a material that can be formed using the ALD method for the protective film. By using the ALD method, it is possible to form a dense protective film with reduced defects such as cracks or pinholes, or a protective film with a uniform thickness. Furthermore, it is possible to reduce the damage inflicted on the processed workpiece when forming the protective film.

[0238] For example, by using the ALD method to form a protective film, it is possible to create a uniform, low-defect protective film on surfaces with complex uneven shapes, or on the top, sides, and back surfaces of a touch panel.

[0239] As described above, a light-emitting device can be obtained using the light-emitting device described in Embodiment 1.

[0240] Since the light-emitting device in this embodiment uses the light-emitting device described in Embodiment 1, a light-emitting device with good characteristics can be obtained. Specifically, because the light-emitting device described in Embodiment 1 has good luminous efficiency, it is possible to make a light-emitting device with low power consumption.

[0241] Figures 3(A) and 3(B) show examples of light-emitting devices in which color purity is improved by providing a colored layer (color filter), etc. Figure 3(A) shows a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a drive circuit portion 1041, anodes 1024R, 1024G, 1024B of the light-emitting device, a partition wall 1025, an EL layer 1028, a second electrode 1029 of the light-emitting device, a sealing substrate 1031, a sealing material 1032, etc.

[0242] In Figure 3(A), the colored layers (red colored layer 1034R, green colored layer 1034G, and blue colored layer 1034B) are provided on a transparent substrate 1033. A black matrix 1035 may also be provided. The transparent substrate 1033 on which the colored layers and black matrix are provided is aligned and fixed to the substrate 1001. The colored layers and black matrix 1035 are covered with an overcoat layer 1036.

[0243] Figure 3(B) shows an example in which colored layers (red colored layer 1034R, green colored layer 1034G, and blue colored layer 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. Thus, the colored layers may also be provided between the substrate 1001 and the encapsulating substrate 1031.

[0244] Furthermore, although the light-emitting device described above is a bottom-emission type light-emitting device with a structure that extracts light from the substrate 1001 on which the FET is formed, it may also be a top-emission type light-emitting device with a structure that extracts light from the sealing substrate 1031 on which the light-emitting device is formed. A cross-sectional view of the top-emission type light-emitting device is shown in Figure 4. In this case, the substrate 1001 can be a substrate that does not transmit light. The process is the same as for the bottom-emission type light-emitting device until the connecting electrode that connects the FET and the anode of the light-emitting device is fabricated. After that, a third interlayer insulating film 1037 is formed covering the electrode 1022. This insulating film may also play a role in planarization. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film 1021, as well as other known materials.

[0245] The anodes 1024R, 1024G, and 1024B of the light-emitting device may also be cathodes. Furthermore, in the case of a top-emission type light-emitting device as shown in Figure 4, it is preferable to use a reflective electrode as the anode. The configuration of the EL layer 1028 is the same as that described as EL layer 103 in Embodiment 1.

[0246] In the top emission structure shown in Figure 4, sealing can be performed with a sealing substrate 1031 having colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B). A black matrix 1035 may also be provided on the sealing substrate 1031 so as to be located between pixels. The colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) or the black matrix 1035 may be covered with an overcoat layer 1036. The sealing substrate 1031 should be a translucent substrate.

[0247] In top-emission type light-emitting devices, a microcavity structure can be suitably applied. A light-emitting device having a microcavity structure is obtained by making one electrode an electrode including a reflective electrode and the other electrode a semi-transparent / semi-reflective electrode. At least an EL layer exists between the reflective electrode and the semi-transparent / semi-reflective electrode, and at least a light-emitting layer that forms an emission region exists.

[0248] The reflective electrode has a visible light reflectance of 40% to 100%, preferably 70% to 100%, and its resistivity is 1 × 10⁻⁶. -2 The film thickness is assumed to be Ωcm or less. Furthermore, the semi-transparent / semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and its resistivity is 1 × 10⁻⁶. -2 Assume the membrane is less than Ωcm in diameter.

[0249] The light emitted from the light-emitting layer contained in the EL layer is reflected by the reflective electrode and the semi-transparent / semi-reflective electrode, causing resonance.

[0250] This light-emitting device allows you to change the optical distance between the reflective electrode and the semi-transparent / semi-reflective electrode by changing the thickness of the transparent conductive film or the aforementioned composite material, carrier transport material, etc. This makes it possible to strengthen light of resonant wavelengths and attenuate light of non-resonant wavelengths between the reflective electrode and the semi-transparent / semi-reflective electrode.

[0251] Furthermore, since the light reflected back by the reflective electrode (first reflected light) interferes significantly with the light that directly enters the semi-transparent / semi-reflective electrode from the light-emitting layer (first incident light), it is preferable to adjust the optical distance between the reflective electrode and the light-emitting layer to (2n-1)λ / 4 (where n is a natural number greater than or equal to 1, and λ is the wavelength of the light emission to be amplified). By adjusting this optical distance, the phases of the first reflected light and the first incident light can be aligned, and the light emission from the light-emitting layer can be further amplified.

[0252] In the above configuration, the EL layer may have a structure with multiple light-emitting layers or a structure with a single light-emitting layer. For example, it may be applied to a configuration in which multiple EL layers are provided in a single light-emitting device with a charge generation layer in between, and one or more light-emitting layers are formed in each EL layer, in combination with the tandem light-emitting device configuration described above.

[0253] By incorporating a microcavity structure, it becomes possible to enhance the emission intensity in the front direction at specific wavelengths, thereby reducing power consumption. Furthermore, in the case of a light-emitting device that displays images using four sub-pixels of red, yellow, green, and blue, in addition to the brightness enhancement effect of yellow emission, a microcavity structure tailored to the wavelength of each color can be applied to all sub-pixels, resulting in a light-emitting device with excellent characteristics.

[0254] Since the light-emitting device in this embodiment uses the light-emitting device described in Embodiment 1, a light-emitting device with good characteristics can be obtained. Specifically, because the light-emitting device described in Embodiment 1 has good luminous efficiency, it is possible to make a light-emitting device with low power consumption.

[0255] Up to this point, we have described an active matrix type light-emitting device, but from here on we will describe a passive matrix type light-emitting device. Figures 5(A) and 5(B) show a passive matrix type light-emitting device manufactured by applying the present invention. Figure 5(A) is a perspective view of the light-emitting device, and Figure 5(B) is a cross-sectional view of Figure 5(A) cut along the dashed line XY. In Figure 5, an EL layer 955 is provided on the substrate 951 between electrodes 952 and 956. The ends of electrodes 952 are covered with an insulating layer 953. A partition layer 954 is provided on the insulating layer 953. The side walls of the partition layer 954 have a slope such that the distance between one side wall and the other side wall narrows as they get closer to the substrate surface. In other words, the cross-section of the partition layer 954 in the short-side direction is trapezoidal, with the bottom side (facing the same direction as the surface direction of the insulating layer 953 and in contact with the insulating layer 953) being shorter than the top side (facing the same direction as the surface direction of the insulating layer 953 and not in contact with the insulating layer 953). By providing the partition layer 954 in this way, it is possible to prevent malfunctions of the light-emitting device caused by static electricity, etc. Furthermore, even in a passive matrix type light-emitting device, the light-emitting device described in Embodiment 1 is used, resulting in a light-emitting device with good reliability or low power consumption.

[0256] As described above, the light-emitting device is suitable for use as a display device for representing images because it is possible to control each of the numerous minute light-emitting devices arranged in a matrix.

[0257] Furthermore, this embodiment can be freely combined with other embodiments.

[0258] (Embodiment 3) [Light-emitting device] The following describes another example of a light-emitting device according to one embodiment of the present invention using the above-mentioned light-emitting device, as well as a method for manufacturing it.

[0259] Figure 14(A) shows a schematic top view of a light-emitting device 450 according to one embodiment of the present invention. The light-emitting device 450 has multiple red light-emitting devices 110R, multiple green light-emitting devices 110G, and multiple blue light-emitting devices 110B. In Figure 14(A), the labels R, G, and B are added within the light-emitting area of ​​each light-emitting device to simplify the distinction between them.

[0260] Light-emitting devices 110R, 110G, and 110B are each arranged in a matrix. Figure 14(A) shows a so-called stripe arrangement in which light-emitting devices of the same color are arranged in one direction. Note that the arrangement method of the light-emitting devices is not limited to this, and arrangement methods such as delta arrangement and zigzag arrangement may be applied, or a pentile arrangement may be used.

[0261] Light-emitting devices 110R, 110G, and 110B are arranged in the X direction. In addition, light-emitting devices of the same color are arranged in the Y direction, which intersects the X direction.

[0262] Light-emitting devices 110R, 110G, and 110B are light-emitting devices having the above configuration.

[0263] Figure 14(B) is a schematic cross-sectional view corresponding to the dashed line A1-A2 in Figure 14(A), and Figure 14(C) is a schematic cross-sectional view corresponding to the dashed line B1-B2.

[0264] Figure 14(B) shows cross-sections of light-emitting devices 110R, 110G, and 110B. Light-emitting device 110R has a first electrode 101R, an EL layer 120R, an EL layer 121, and a second electrode 102. Light-emitting device 110G has a first electrode 101G, an EL layer 120G, an EL layer (electron injection layer) 115, and a second electrode 102. Light-emitting device 110B has a first electrode 101B, an EL layer 120B, an EL layer 121, and a second electrode 102. The EL layer 121 and the second electrode 102 are provided in common to light-emitting devices 110R, 110G, and 110B. The EL layer 121 can also be called a common layer.

[0265] The EL layer 120R of the light-emitting device 110R has a luminescent organic compound that emits light having intensity in at least the red wavelength range. The EL layer 120G of the light-emitting device 110G has a luminescent organic compound that emits light having intensity in at least the green wavelength range. The EL layer 120B of the light-emitting device 110B has a luminescent organic compound that emits light having intensity in at least the blue wavelength range. At least one of the light-emitting devices 110R, 110G, and 110B is a light-emitting device according to one aspect of the present invention, and it is preferable that the light-emitting device is the light-emitting device 110B.

[0266] EL layers 120R, 120G, and 120B each have at least an emissive layer and a hole transport layer, and may also have one or more of the following: an electron injection layer, an electron transport layer, a hole injection layer, a carrier block layer, an exciton block layer, etc. EL layer 121 may have a configuration without an emissive layer. Preferably, EL layer 121 is an electron injection layer. If the electron transport layer also functions as an electron injection layer, EL layer 121 may not be provided.

[0267] The first electrode 101R, the first electrode 101G, and the first electrode 101B are provided for each light-emitting device. The second electrode 102 and the EL layer 121 are provided as a continuous layer common to each light-emitting device. Furthermore, although the hole transport layers in the EL layer 120R, EL layer 120G, and EL layer 120B are interrupted between light-emitting devices with different emission colors, it is preferable that they have the same configuration.

[0268] A conductive film that is transparent to visible light is used on either the first electrode 101 or the second electrode 102, and a conductive film that is reflective is used on the other. By making the first electrode 101 transparent and the second electrode 102 reflective, a bottom-emission type display device can be made, and conversely, by making the first electrode 101 reflective and the second electrode 102 transparent, a top-emission type display device can be made. Furthermore, by making both the first electrode 101 and the second electrode 102 transparent, a dual-emission type display device can be made. One embodiment of the present invention is suitable for a top-emission type light-emitting device.

[0269] An insulating layer 124 is provided covering the ends of the first electrode 101R, the first electrode 101G, and the first electrode 101B. Preferably, the ends of the insulating layer 124 are tapered. The insulating layer 124 may be omitted if it is not needed.

[0270] Each of the EL layers 120R, 120G, and 120B has a region in contact with the upper surface of the pixel electrode and a region in contact with the surface of the insulating layer 124. The edges of the EL layers 120R, 120G, and 120B are located on the insulating layer 124.

[0271] As shown in Figure 14(B), a gap is provided between the two EL layers in light-emitting devices of different colors. It is preferable that the EL layers 120R, 120G, and 120B are arranged so that they do not touch each other. This effectively prevents current from flowing through two adjacent EL layers and causing unintended light emission. Therefore, contrast can be enhanced, and a display device with high display quality can be realized.

[0272] Figure 14(C) shows an example in which the EL layer 120R is formed in a strip shape so that it is continuous in the Y direction. By forming the EL layer 120R in a strip shape, the space required to separate them is eliminated, and the area of ​​the non-emitting region between light-emitting devices can be reduced, thereby increasing the aperture ratio. Although Figure 14(C) shows a cross-section of light-emitting device 110R as an example, the same shape can be used for light-emitting devices 110G and 110B. The EL layer may also be separated for each light-emitting device in the Y direction.

[0273] A protective layer 131 is provided on the second electrode 102, covering the light-emitting devices 110R, 110G, and 110B. The protective layer 131 has the function of preventing impurities such as water from diffusing to each light-emitting device from above.

[0274] The protective layer 131 can be, for example, a single-layer structure or a multilayer structure including at least an inorganic insulating film. Examples of inorganic insulating films include oxide films or nitride films such as silicon oxide film, silicon oxide nitride film, silicon oxide nitride film, silicon nitride film, aluminum oxide film, aluminum oxide nitride film, and hafnium oxide film. Alternatively, semiconductor materials such as indium gallium oxide and indium gallium zinc oxide may be used as the protective layer 131.

[0275] Furthermore, a laminated film of an inorganic insulating film and an organic insulating film can also be used as the protective layer 131. For example, it is preferable to have a configuration in which an organic insulating film is sandwiched between a pair of inorganic insulating films. It is also preferable that the organic insulating film functions as a planarizing film. This makes the upper surface of the organic insulating film flat, thereby improving the coverage of the inorganic insulating film on top of it and enhancing its barrier properties. In addition, since the upper surface of the protective layer 131 is flat, it is preferable because it reduces the influence of uneven shapes caused by the structure below when a structure (e.g., a color filter, touch sensor electrodes, or lens array, etc.) is provided above the protective layer 131.

[0276] Figure 14(A) also shows a connecting electrode 101C that is electrically connected to the second electrode 102. The connecting electrode 101C is supplied with a potential (e.g., anode potential or cathode potential) to the second electrode 102. The connecting electrode 101C is located outside the display area where the light-emitting devices 110R and the like are arranged. Figure 14(A) also shows the second electrode 102 with a dashed line.

[0277] The connecting electrode 101C can be provided along the outer perimeter of the display area. For example, it may be provided along one side of the outer perimeter of the display area, or it may be provided across two or more sides of the outer perimeter of the display area. That is, if the top surface shape of the display area is rectangular, the top surface shape of the connecting electrode 101C can be a strip, L-shape, U-shape (angle bracket shape), or square, etc.

[0278] Figure 14(D) is a schematic cross-sectional view corresponding to the dashed line C1-C2 in Figure 14(A). Figure 14(D) shows a connection portion 130 where the connecting electrode 101C and the second electrode 102 are electrically connected. In the connection portion 130, the second electrode 102 is provided in contact with the connecting electrode 101C, and a protective layer 131 is provided covering the second electrode 102. In addition, an insulating layer 124 is provided covering the end of the connecting electrode 101C.

[0279] [Example of manufacturing method] In the following, an example of a method for manufacturing a display device according to one aspect of the present invention will be described with reference to the drawings. Here, the light-emitting device 450 shown in the above configuration example will be used as an example. Figures 15(A) to 15(F) are schematic cross-sectional views of each step in the method for manufacturing the display device illustrated below. In addition, in Figure 15(A), etc., schematic cross-sectional views of the connection part 130 and its vicinity are also shown on the right side.

[0280] The thin films (insulating films, semiconductor films, conductive films, etc.) that make up the display device can be formed using sputtering, chemical vapor deposition (CVD), vacuum deposition, pulsed laser deposition (PLD), atomic layer deposition (ALD), and other methods. CVD methods include plasma-enhanced CVD (PECVD) and thermal CVD. One type of thermal CVD is metal-organic CVD (MOCVD).

[0281] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by methods such as spin coating, dip coating, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife coating, slit coating, roll coating, curtain coating, and knife coating.

[0282] Furthermore, when processing the thin films that constitute the display device, photolithography or the like can be used. In addition, the thin films may be processed by nanoimprint lithography, sandblasting, lift-off lithography, or the like. Alternatively, island-shaped thin films may be directly formed by a film deposition method using a shielding mask such as a metal mask.

[0283] There are two main methods of photolithography. One method involves forming a resist mask on the thin film to be processed, then processing the thin film by etching or other means, and removing the resist mask. The other method involves forming a photosensitive thin film, then exposing and developing it to process the thin film into the desired shape.

[0284] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture thereof. Other light sources such as ultraviolet light, KrF laser light, or ArF laser light can also be used. Exposure may also be performed using immersion lithography. Furthermore, extreme ultraviolet (EUV) light, X-rays, etc., may be used as the light source for exposure. An electron beam can also be used instead of the light source for exposure. Using extreme ultraviolet light, X-rays, or an electron beam is preferable because it enables extremely fine processing. Note that a photomask is not required when exposure is performed by scanning a beam such as an electron beam.

[0285] For etching thin films, methods such as dry etching, wet etching, and sandblasting can be used.

[0286] [Preparation of circuit board 100] As the substrate 100, a substrate having at least sufficient heat resistance to withstand subsequent heat treatment can be used. When an insulating substrate is used as the substrate 100, glass substrates, quartz substrates, sapphire substrates, ceramic substrates, organic resin substrates, etc., can be used. In addition, semiconductor substrates such as single-crystal semiconductor substrates made of silicon, silicon carbide, etc., polycrystalline semiconductor substrates, compound semiconductor substrates such as silicon germanium, and SOI substrates can be used.

[0287] In particular, it is preferable to use a substrate 100 on which a semiconductor circuit including semiconductor elements such as transistors is formed on the semiconductor substrate or insulating substrate. It is preferable that the semiconductor circuit constitutes, for example, a pixel circuit, a gate line driving circuit (gate driver), a source line driving circuit (source driver), etc. In addition to the above, an arithmetic circuit, a memory circuit, etc. may also be configured.

[0288] [Formation of the first electrodes 101R, 101G, 101B and the connecting electrode 101C] Next, the first electrode 101R, the first electrode 101G, the first electrode 101B, and the connecting electrode 101C are formed on the substrate 100. First, a conductive film to be the anode (pixel electrode) is deposited, a resist mask is formed by photolithography, and unnecessary parts of the conductive film are removed by etching. After that, the resist mask is removed to form the first electrode 101R, the first electrode 101G, and the first electrode 101B.

[0289] When using a conductive film that is reflective to visible light as each pixel electrode, it is preferable to use a material (for example, silver or aluminum) that has the highest possible reflectivity across the entire wavelength range of visible light. This not only improves the light extraction efficiency of the light-emitting device but also enhances color reproduction. When a conductive film that is reflective to visible light is used as each pixel electrode, it is possible to create a so-called top-emission light-emitting device that extracts light in the direction opposite to the substrate. When a transparent conductive film is used as each pixel electrode, it is possible to create a so-called bottom-emission light-emitting device that extracts light in the direction of the substrate.

[0290] [Formation of insulating layer 124] Next, an insulating layer 124 is formed by covering the ends of the first electrode 101R, the first electrode 101G, and the first electrode 101B (Figure 15(A)). An organic insulating film or an inorganic insulating film can be used as the insulating layer 124. It is preferable that the ends of the insulating layer 124 be tapered in order to improve the step coverage of the EL film that will be formed later. In particular, when using an organic insulating film, it is preferable to use a photosensitive material because it is easier to control the shape of the ends depending on the exposure and development conditions. If the insulating layer 124 is not provided, it becomes possible to bring the distance between the light-emitting devices even closer, making it possible to obtain a light-emitting device with higher resolution.

[0291] [Formation of EL film 120Rb] Next, an EL film 120Rb, which will later become the EL layer 120R, is formed on the first electrode 101R, the first electrode 101G, the first electrode 101B, and the insulating layer 124.

[0292] The EL film 120Rb has an emissive layer containing at least a light-emitting material and a hole transport layer. In addition, it may have a structure in which one or more films functioning as an electron injection layer, electron transport layer, charge generation layer, or hole injection layer are laminated. The EL film 120Rb can be formed by, for example, vapor deposition, sputtering, or inkjet. However, it is not limited to these, and the above-mentioned film formation methods can be used as appropriate.

[0293] As an example, it is preferable that the EL film 120Rb be a laminated film in which a hole injection layer, a hole transport layer, an emissive layer, and an electron transport layer are stacked in this order. In this case, the EL layer to be formed later can be a film having an electron injection layer 115. In a light-emitting device according to one aspect of the present invention, by providing an electron transport layer covering the emissive layer, it is possible to suppress damage to the emissive layer by subsequent photolithography processes, and a highly reliable light-emitting device can be manufactured.

[0294] It is preferable that the EL film 120Rb is formed so as not to be present on the connecting electrode 101C. For example, when the EL film 120Rb is formed by vapor deposition (or sputtering), it is preferable to form it using a shielding mask or to remove it in a later etching step so that the EL film 120Rb is not deposited on the connecting electrode 101C.

[0295] [Formation of sacrificial film 144a] Next, a sacrificial film 144a is formed by covering the EL film 120Rb. The sacrificial film 144a is also provided in contact with the upper surface of the connecting electrode 101C.

[0296] The sacrificial film 144a can be a film with high resistance to etching of each EL film, such as the EL film 120Rb, i.e., a film with a high etching selectivity ratio. Alternatively, the sacrificial film 144a can be a film with a high etching selectivity ratio with protective films, such as the protective film 146a described later. Furthermore, the sacrificial film 144a can be a film that can be removed by a wet etching method that causes minimal damage to each EL film.

[0297] As the sacrificial film 144a, for example, a metal film, alloy film, metal oxide film, semiconductor film, or inorganic film such as an inorganic insulating film can be used. The sacrificial film 144a can be formed by various film deposition methods such as sputtering, vapor deposition, CVD, and ALD.

[0298] As the sacrificial film 144a, for example, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metallic materials, can be used. In particular, it is preferable to use low-melting-point materials such as aluminum or silver.

[0299] Furthermore, metal oxides such as indium gallium zinc oxide (In-Ga-Zn oxide, also written as IGZO) can be used as the sacrificial film 144a. In addition, indium oxide, indium zinc oxide (In-Zn oxide), indium tin oxide (In-Sn oxide), indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), etc. can be used. Alternatively, indium tin oxide containing silicon can also be used.

[0300] Furthermore, the above-mentioned method can also be applied when element M (where M is one or more selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium) is used instead of gallium. In particular, it is preferable that M be one or more selected from gallium, aluminum, or yttrium.

[0301] Furthermore, inorganic insulating materials such as aluminum oxide, hafnium oxide, and silicon oxide can be used as the sacrificial film 144a.

[0302] Furthermore, it is preferable to use a material that is soluble in a chemically stable solvent as the sacrificial film 144a, at least for the film located on the uppermost part of the EL film 120Rb. In particular, materials soluble in water or alcohol can be suitably used for the sacrificial film 144a. When forming the sacrificial film 144a, it is preferable to dissolve the material in a solvent such as water or alcohol, apply it using a wet deposition method, and then perform a heat treatment to evaporate the solvent. At this time, performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature and in a short time, thereby reducing thermal damage to the EL film 120Rb.

[0303] Wet film deposition methods that can be used to form the sacrificial film 144a include spin coating, dip coating, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, and knife coating.

[0304] As the sacrificial film 144a, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used.

[0305] [Formation of protective film 146a] Next, a protective film 146a is formed on the sacrificial film 144a (Figure 15(B)).

[0306] The protective film 146a is used as a hard mask when etching the sacrificial film 144a later. Furthermore, the sacrificial film 144a is exposed during the subsequent processing of the protective film 146a. Therefore, a combination of films with a high etching selectivity ratio for each other is selected for the sacrificial film 144a and the protective film 146a. Thus, the film that can be used for the protective film 146a can be selected according to the etching conditions for both the sacrificial film 144a and the protective film 146a.

[0307] For example, when dry etching using a fluorine-containing gas (also called a fluorine-based gas) is used to etch the protective film 146a, silicon, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum, tantalum nitride, an alloy containing molybdenum and niobium, or an alloy containing molybdenum and tungsten can be used for the protective film 146a. Here, metal oxide films such as IGZO and ITO can be used as sacrificial films 144a, as they allow for a higher selectivity ratio for etching (i.e., a slower etching rate) compared to the dry etching using the above-mentioned fluorine-based gas.

[0308] However, the protective film 146a can be selected from a variety of materials depending on the etching conditions of the sacrificial film 144a and the protective film 146a. For example, it can be selected from films that can be used for the sacrificial film 144a.

[0309] Furthermore, a nitride film can be used as the protective film 146a, for example. Specifically, nitrides such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, and germanium nitride can be used.

[0310] Alternatively, an oxide film can be used as the protective film 146a. Typically, oxide films or oxynitride films such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, and hafnium oxynitride can be used.

[0311] Furthermore, an organic film that can be used for the EL film 120Rb may be used as the protective film 146a. For example, the same organic film used for the EL film 120Rb and EL film 120Gb can be used for the protective film 146a. Using such an organic film is preferable because it allows the same film deposition equipment to be used for both the EL film 120Rb and the protective film 146a.

[0312] [Formation of resist mask 143a] Next, a resist mask 143a is formed on the protective film 146a at a position overlapping with the first electrode 101R and at a position overlapping with the connecting electrode 101C, respectively (Figure 15(C)).

[0313] The resist mask 143a can use a resist material containing a photosensitive resin, such as a positive-type resist material or a negative-type resist material.

[0314] In this case, if a resist mask 143a is formed on the sacrificial film 144a without a protective film 146a, there is a risk that the EL film 120Rb may dissolve due to the solvent of the resist material if there are defects such as pinholes in the sacrificial film 144a. Using a protective film 146a can prevent such problems from occurring.

[0315] Furthermore, if a sacrificial film 144a is used that is less prone to defects such as pinholes, the resist mask 143a may be formed directly on the sacrificial film 144a without using the protective film 146a.

[0316] [Etching of protective film 146a] Next, the portion of the protective film 146a not covered by the resist mask 143a is removed by etching to form a strip-shaped protective layer 147a. At the same time, a protective layer 147a is also formed on the connecting electrode 101C.

[0317] When etching the protective film 146a, it is preferable to use etching conditions with a high selectivity ratio so that the sacrificial film 144a is not removed by the etching. The protective film 146a can be etched by wet etching or dry etching, but using dry etching can suppress the reduction of the pattern of the protective film 146a.

[0318] [Removal of resist mask 143a] Next, remove the resist mask 143a (Figure 15(D)).

[0319] The resist mask 143a can be removed by wet etching or dry etching. In particular, it is preferable to remove the resist mask 143a by dry etching (also called plasma ashing) using oxygen gas as the etching gas.

[0320] In this case, the removal of the resist mask 143a is performed while the EL film 120Rb is covered by the sacrificial film 144a, thus suppressing the impact on the EL film 120Rb. In particular, since contact with oxygen can adversely affect the electrical properties of the EL film 120Rb, this method is suitable when etching is performed using oxygen gas, such as plasma ashing.

[0321] [Etching of sacrificial film 144a] Next, using the protective layer 147a as a mask, the portion of the sacrificial film 144a not covered by the protective layer 147a is removed by etching to form a strip-shaped sacrificial layer 145a (Figure 15(E)). At the same time, a sacrificial layer 145a is also formed on the connecting electrode 101C.

[0322] The sacrificial film 144a can be etched by wet etching or dry etching, but dry etching is preferred because it can suppress pattern reduction.

[0323] [Etching of EL film 120Rb and protective layer 147a] Next, the protective layer 147a is etched, and at the same time, a portion of the EL film 120Rb not covered by the sacrificial layer 145a is removed by etching, forming a strip-shaped EL layer 120R (Figure 15(F)). At the same time, the protective layer 147a on the connecting electrode 101C is also removed.

[0324] Etching the EL film 120Rb and the protective layer 147a using the same process simplifies the manufacturing process and reduces the cost of producing the display device, which is therefore preferable.

[0325] In particular, for etching the EL film 120Rb, it is preferable to use dry etching with an etching gas that does not contain oxygen as its main component. This suppresses the deterioration of the EL film 120Rb and enables the realization of a highly reliable display device. Examples of etching gases that do not contain oxygen as their main component include noble gases such as CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, H2, or He. Alternatively, a mixed gas of the above gases and an oxygen-free diluent gas can be used as the etching gas.

[0326] The etching of the EL film 120Rb and the protective layer 147a may be performed separately. In this case, the EL film 120Rb may be etched first, or the protective layer 147a may be etched first.

[0327] At this point, the EL layer 120R and the connecting electrode 101C are covered by the sacrificial layer 145a.

[0328] [Formation of EL film 120Gb] Next, an EL film 120Gb, which will later become the EL layer 120G, is formed on the sacrificial layer 145a, the insulating layer 124, the first electrode 101G, and the first electrode 101B. At this time, it is preferable not to provide the EL film 120Gb on the connecting electrode 101C, similar to the EL film 120Rb.

[0329] The method for forming the EL film 120Gb can be described by referring to the description of the EL film 120Rb above.

[0330] [Formation of sacrificial film 144b] Next, a sacrificial film 144b is formed on the EL film 120Gb. The sacrificial film 144b can be formed in the same manner as the sacrificial film 144a. In particular, it is preferable to use the same material for the sacrificial film 144b as for the sacrificial film 144a.

[0331] At the same time, a sacrificial film 144a is formed on the connecting electrode 101C, covering the sacrificial layer 145a.

[0332] [Formation of protective film 146b] Next, a protective film 146b is formed on the sacrificial film 144b. The protective film 146b can be formed in the same manner as the protective film 146a. In particular, it is preferable to use the same material for the protective film 146b as for the protective film 146a.

[0333] [Formation of resist mask 143b] Next, a resist mask 143b is formed on the protective film 146b in the region overlapping with the first electrode 101G and the region overlapping with the connecting electrode 101C (Figure 16(A)).

[0334] The resist mask 143b can be formed in the same manner as the resist mask 143a.

[0335] [Etching of protective film 146b] Next, the portion of the protective film 146b not covered by the resist mask 143b is removed by etching to form a strip-shaped protective layer 147b (Figure 16(B)). At the same time, a protective layer 147b is also formed on the connecting electrode 101C.

[0336] For etching of protective film 146b, the description of protective film 146a above can be applied.

[0337] [Removal of resist mask 143b] Next, remove the resist mask 143b. The removal of resist mask 143b can be done by referring to the description of resist mask 143a above.

[0338] [Etching of sacrificial film 144b] Next, using the protective layer 147b as a mask, the portion of the sacrificial film 144b not covered by the protective layer 147b is removed by etching to form a strip-shaped sacrificial layer 145b. At the same time, a sacrificial layer 145b is also formed on the connecting electrode 101C. Sacrificial layers 145a and 145b are stacked on the connecting electrode 101C.

[0339] The etching of the sacrificial film 144b can be performed by referring to the description of the sacrificial film 144a above.

[0340] [Etching of EL film 120Gb and protective layer 147b] Next, the protective layer 147b is etched, and at the same time, a portion of the EL film 120Gb that is not covered by the sacrificial layer 145b is removed by etching, forming a strip-shaped EL layer 120G (Figure 16(C)). At the same time, the protective layer 147b on the connecting electrode 101C is also removed.

[0341] Etching of the EL film 120Gb and protective layer 147b can be performed by referring to the description of the EL film 120Rb and protective layer 147a above.

[0342] In this case, the EL layer 120R is protected by the sacrificial layer 145a, thus preventing it from being damaged during the etching process of the EL film 120Gb.

[0343] In this way, the strip-shaped EL layer 120R and the strip-shaped EL layer 120G can be manufactured with high positional accuracy.

[0344] [Formation of EL layer 120B] By performing the above steps on the EL film 120Bb (not shown), island-shaped EL layers 120B and island-shaped sacrificial layers 145c can be formed (Figure 16(D)).

[0345] Specifically, after the formation of the EL layer 120G, the EL film 120Bb, sacrificial film 144c, protective film 146c, and resist mask 143c (none of which are shown) are formed in order. Next, the protective film 146c is etched to form a protective layer 147c (not shown), and then the resist mask 143c is removed. Subsequently, the sacrificial film 144c is etched to form a sacrificial layer 145c. After that, the protective layer 147c and the EL film 120Bb are etched to form a strip-shaped EL layer 120B.

[0346] Furthermore, after the formation of the EL layer 120B, a sacrificial layer 145c is simultaneously formed on the connecting electrode 101C. Sacrificial layers 145a, 145b, and 145c are stacked on the connecting electrode 101C.

[0347] [Removal of the sacrificial layer] Next, sacrificial layers 145a, 145b, and 145c are removed, exposing the upper surfaces of EL layers 120R, 120G, and 120B (Figure 16(E)). At the same time, the upper surface of the connecting electrode 101C is also exposed.

[0348] Sacrificial layers 145a, 145b, and 145c can be removed by wet etching or dry etching. In this case, it is preferable to use a method that minimizes damage to EL layers 120R, 120G, and 120B. In particular, wet etching is preferred. For example, it is preferable to use wet etching with an aqueous solution of tetramethylammonium hydroxide (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0349] Alternatively, it is preferable to remove the sacrificial layers 145a, 145b, and 145c by dissolving them in a solvent such as water or alcohol. Here, various alcohols can be used as the alcohol that can dissolve the sacrificial layers 145a, 145b, and 145c, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0350] After removing sacrificial layers 145a, 145b, and 145c, it is preferable to perform a drying treatment to remove water contained inside EL layers 120R, 120G, and 120B, as well as water adsorbed on the surface. For example, it is preferable to perform a heat treatment under an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C to 200°C, preferably 60°C to 150°C, and more preferably 70°C to 120°C. A reduced pressure atmosphere is preferable because it allows drying at a lower temperature.

[0351] In this way, EL layer 120R, EL layer 120G, and EL layer 120B can be manufactured separately.

[0352] [Formation of electron injection layer 115] Next, an electron injection layer 115 is formed to cover the EL layer 120R, EL layer 120G, and EL layer 120B.

[0353] The electron injection layer 115 can be deposited using the same method as the EL film 120Rb. When depositing the electron injection layer 115 by vapor deposition, it is preferable to use a shielding mask to prevent the electron injection layer 115 from being deposited on the connecting electrode 101C.

[0354] [Formation of the second electrode 102] Next, the electron injection layer 115 and the connecting electrode 101C are covered to form the second electrode 102 (Figure 16(F)).

[0355] The second electrode 102 can be formed by a film deposition method such as vapor deposition or sputtering. Alternatively, a film formed by vapor deposition and a film formed by sputtering may be laminated together. In this case, it is preferable to form the second electrode 102 so as to encompass the region in which the electron injection layer 115 is formed. That is, the edge of the electron injection layer 115 can overlap with the second electrode 102. It is preferable to form the second electrode 102 using a shielding mask.

[0356] The second electrode 102 is electrically connected to the connecting electrode 101C outside the display area.

[0357] [Formation of a protective layer] Next, a protective layer is formed on the second electrode 102. For the formation of the inorganic insulating film used in the protective layer, sputtering, PECVD, or ALD methods are preferred. The ALD method is particularly preferred because it offers excellent step coverage and is less prone to defects such as pinholes. Furthermore, for the formation of the organic insulating film, the inkjet method is preferred because it allows for the formation of a uniform film in the desired area.

[0358] Based on the above, a light-emitting device according to one aspect of the present invention can be manufactured.

[0359] In the above example, the case where the second electrode 102 and the electron injection layer 115 are formed with different upper surface shapes is shown, but they may also be formed in the same region.

[0360] In this specification, devices fabricated using a metal mask or FMM (Fine Metal Mask, a high-resolution metal mask) may be referred to as MM (Metal Mask) structured devices. In addition, in this specification, devices fabricated without using a metal mask or FMM may be referred to as MML (Metal Maskless) structured devices.

[0361] (Embodiment 4) In this embodiment, an example of using the light-emitting device described in Embodiment 1 as an illumination device will be explained with reference to Figure 6. Figure 6(B) is a top view of the illumination device, and Figure 6(A) is a cross-sectional view along the line segment ef shown in Figure 6(B).

[0362] In this embodiment, the lighting device has an anode 401 formed on a translucent substrate 400 which serves as a support. The anode 401 corresponds to the first electrode 101 in Embodiment 1. When light is extracted from the anode 401 side, the anode 401 is formed from a translucent material.

[0363] A pad 412 for supplying voltage to the cathode 404 is formed on the substrate 400.

[0364] An EL layer 403 is formed on the anode 401. The EL layer 403 corresponds to the configuration of the EL layer 103 in Embodiment 1, etc. Please refer to the relevant description for details on these configurations.

[0365] A cathode 404 is formed by covering the EL layer 403. The cathode 404 corresponds to the second electrode 102 in Embodiment 1. When light emission is extracted from the anode 401 side, the cathode 404 is formed of a material with high reflectivity. Voltage is supplied to the cathode 404 by connecting it to the pad 412.

[0366] As described above, the lighting device shown in this embodiment has a light-emitting device having an anode 401, an EL layer 403, and a cathode 404. Since this light-emitting device is a light-emitting device with high luminous efficiency, the lighting device in this embodiment can be a lighting device with low power consumption.

[0367] The lighting device is completed by fixing and sealing the substrate 400, on which the light-emitting device having the above configuration is formed, and the sealing substrate 407 using sealing materials 405 and 406. Either sealing material 405 or 406 may be used. In addition, a desiccant can be mixed into the inner sealing material 406 (not shown in Figure 6(B)), which allows for the adsorption of moisture and leads to improved reliability.

[0368] Furthermore, by extending a portion of the pad 412 and anode 401 outside the sealing materials 405 and 406, they can be used as external input terminals. Alternatively, an IC chip 420 with a converter or the like may be placed on top of them.

[0369] As described above, the lighting device described in this embodiment uses the light-emitting device described in Embodiment 1 as the EL element, and can be a lighting device with low power consumption.

[0370] Furthermore, this embodiment can be freely combined with other embodiments.

[0371] (Embodiment 5) This embodiment describes an example of an electronic device that includes the light-emitting device described in Embodiment 1 as part of it. The light-emitting device described in Embodiment 1 has good luminous efficiency and low power consumption. As a result, the electronic device described in this embodiment can be an electronic device having a light-emitting section with low power consumption.

[0372] Examples of electronic devices to which the above-mentioned light-emitting devices are applied include television equipment (also called televisions or television receivers), monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game consoles, personal digital assistants, sound playback devices, and large game machines such as pachinko machines. Specific examples of these electronic devices are shown below.

[0373] Figure 7(A) shows an example of a television system. The television system has a display unit 7103 incorporated into a housing 7101. This figure also shows a configuration in which the housing 7101 is supported by a stand 7105. The display unit 7103 is capable of displaying images, and the display unit 7103 is constructed by arranging the light-emitting devices described in Embodiment 1 in a matrix.

[0374] The television system can be operated using the operation switches on the housing 7101 or a separate remote control unit 7110. The operation keys 7109 on the remote control unit 7110 allow for channel or volume control, and the image displayed on the display unit 7103 can be controlled. The remote control unit 7110 may also be configured to include a display unit 7107 that displays information output from the remote control unit 7110. The display unit 7107 can also be fitted with the light-emitting devices described in Embodiment 1, arranged in a matrix.

[0375] The television system shall consist of a receiver or modem. The receiver will be able to receive general television broadcasts, and by connecting to a wired or wireless communication network via the modem, it will also be possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0376] Figure 7(B1) shows a computer, which includes a main unit 7201, a housing 7202, a display unit 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, etc. This computer is manufactured by arranging the light-emitting devices described in Embodiment 1 in a matrix and using them in the display unit 7203. The computer in Figure 7(B1) may also take the form shown in Figure 7(B2). The computer in Figure 7(B2) has a display unit 7210 instead of a keyboard 7204 and a pointing device 7206. The display unit 7210 is a touch panel, and input can be performed by operating the input display shown on the display unit 7210 with a finger or a dedicated pen. In addition to the input display, the display unit 7210 can also display other images. The display unit 7203 may also be a touch panel. The two screens are connected by a hinge, which prevents problems such as scratching or damaging the screens when storing or transporting the device.

[0377] Figure 7(C) shows an example of a mobile terminal. The mobile phone includes a display unit 7402 built into the housing 7401, as well as operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. The mobile phone has a display unit 7402 made by arranging the light-emitting devices described in Embodiment 1 in a matrix.

[0378] The mobile terminal shown in Figure 7(C) can also be configured to allow information to be entered by touching the display unit 7402 with a finger or other object. In this case, operations such as making a phone call or composing an email can be performed by touching the display unit 7402 with a finger or other object.

[0379] The display unit 7402 has three main modes. The first is a display mode that primarily displays images, the second is an input mode that primarily inputs information such as text, and the third is a display + input mode that combines the display mode and the input mode.

[0380] For example, when making a phone call or composing an email, the display unit 7402 should be set to a text input mode, which primarily focuses on text input, and the user should perform the text input operation displayed on the screen. In this case, it is preferable to display a keyboard or number buttons on most of the screen of the display unit 7402.

[0381] Furthermore, by providing a detection device with a tilt sensor such as a gyroscope or accelerometer inside the mobile terminal, it is possible to determine the orientation of the mobile terminal (portrait or landscape) and automatically switch the screen display of the display unit 7402.

[0382] Furthermore, the screen mode can be switched by touching the display unit 7402 or by operating the operation button 7403 on the housing 7401. It is also possible to switch modes depending on the type of image displayed on the display unit 7402. For example, if the image signal displayed on the display unit is video data, it can be switched to display mode; if it is text data, it can be switched to input mode.

[0383] Furthermore, in input mode, the system may detect a signal detected by the optical sensor of the display unit 7402 and, if there is no input via touch operation on the display unit 7402 for a certain period of time, control may be made to switch the screen mode from input mode to display mode.

[0384] The display unit 7402 can also function as an image sensor. For example, by touching the display unit 7402 with the palm or finger, palm prints, fingerprints, etc., can be captured to perform user authentication. Furthermore, by using a backlight that emits near-infrared light or a sensing light source that emits near-infrared light in the display unit, finger veins, palm veins, etc., can also be captured.

[0385] Furthermore, the configuration shown in this embodiment can be used by appropriately combining the configurations shown in Embodiments 1 to 4.

[0386] As described above, the application range of the light-emitting device equipped with the light-emitting device described in Embodiment 1 or Embodiment 2 is extremely broad, and this light-emitting device can be applied to electronic devices in all fields. By using the light-emitting device described in Embodiment 1 or Embodiment 2, it is possible to obtain electronic devices with low power consumption.

[0387] Figure 8(A) is a schematic diagram showing an example of a cleaning robot.

[0388] The cleaning robot 5100 has a display 5101 on its top surface, multiple cameras 5102 on its sides, a brush 5103, and control buttons 5104. Although not shown in the illustration, the cleaning robot 5100 also has wheels, a suction port, etc. on its underside. The cleaning robot 5100 is also equipped with various sensors, including an infrared sensor, an ultrasonic sensor, an accelerometer, a piezoelectric sensor, a light sensor, and a gyroscope. Furthermore, the cleaning robot 5100 is equipped with a means of wireless communication.

[0389] The cleaning robot 5100 is self-propelled, can detect dirt 5120, and can suck up the dirt through a suction port located on its underside.

[0390] Furthermore, the cleaning robot 5100 can analyze images captured by the camera 5102 to determine the presence or absence of obstacles such as walls, furniture, or steps. If the image analysis detects objects that could become entangled in the brush 5103, such as wiring, it can stop the brush 5103 from rotating.

[0391] The display 5101 can display information such as the remaining battery level or the amount of dirt collected. The path taken by the cleaning robot 5100 may also be displayed on the display 5101. Alternatively, the display 5101 may be a touch panel, and operation buttons 5104 may be provided on the display 5101.

[0392] The cleaning robot 5100 can communicate with a portable electronic device 5140, such as a smartphone. Images captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the cleaning robot 5100 can check the status of the room even when they are away from home. In addition, the display on the display 5101 can be checked on a portable electronic device such as a smartphone.

[0393] A light-emitting device according to one aspect of the present invention can be used in a display 5101.

[0394] The robot 2100 shown in Figure 8(B) includes a computing unit 2110, an illuminance sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0395] The microphone 2102 has the function of detecting the user's voice and ambient sounds. The speaker 2104 has the function of emitting sound. The robot 2100 can communicate with the user using the microphone 2102 and speaker 2104.

[0396] The display 2105 has the function of displaying various types of information. The robot 2100 can display the information desired by the user on the display 2105. The display 2105 may be equipped with a touch panel. The display 2105 may also be a detachable information terminal, and by installing it in a fixed position on the robot 2100, charging and data transfer can be made possible.

[0397] The upper camera 2103 and the lower camera 2106 have the function of imaging the area around the robot 2100. In addition, the obstacle sensor 2107 can detect the presence or absence of obstacles in the direction of travel when the robot 2100 moves forward using the movement mechanism 2108. The robot 2100 can recognize its surrounding environment and move safely using the upper camera 2103, the lower camera 2106 and the obstacle sensor 2107. The light-emitting device according to one aspect of the present invention can be used in the display 2105.

[0398] Figure 8(C) shows an example of a goggle-type display. The goggle-type display includes, for example, a housing 5000, a first display unit 5001, a speaker 5003, an LED lamp 5004 (including a power switch or operation switch), a connection terminal 5006, a sensor 5007 (including a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation), a microphone 5008, a second display unit 5002, a support unit 5012, an earphone 5013, etc.

[0399] A light-emitting device according to one aspect of the present invention can be used in a first display unit 5001 and a second display unit 5002.

[0400] Figure 9 shows an example in which the light-emitting device described in Embodiment 1 is used in a desk lamp, which is a lighting device. The desk lamp shown in Figure 9 has a housing 2001 and a light source 2002, and the lighting device described in Embodiment 4 may be used as the light source 2002.

[0401] Figure 10 shows an example of using the light-emitting device described in Embodiment 1 as an indoor lighting device 3001. Since the light-emitting device described in Embodiment 1 is a light-emitting device with high luminous efficiency, it can be used as a lighting device with low power consumption. Furthermore, since the light-emitting device described in Embodiment 1 can be made to cover a large area, it can be used as a large-area lighting device. In addition, since the light-emitting device described in Embodiment 1 is thin, it can be used as a thin lighting device.

[0402] The light-emitting device described in Embodiment 1 can also be mounted on the windshield or dashboard of an automobile. Figure 11 shows one embodiment in which the light-emitting device described in Embodiment 1 is used on the windshield or dashboard of an automobile. Display areas 5200 to 5203 are display areas provided using the light-emitting device described in Embodiment 1.

[0403] Display area 5200 and display area 5201 are display devices equipped with the light-emitting device described in Embodiment 1, which is installed on the windshield of an automobile. The light-emitting device described in Embodiment 1 can be made into a so-called see-through display device, where the opposite side is visible, by making the anode and cathode from translucent electrodes. If the display is in a see-through state, it can be installed on the windshield of an automobile without obstructing the view. When providing transistors for driving, it is preferable to use translucent transistors such as organic transistors made of organic semiconductor materials or transistors using oxide semiconductors.

[0404] The display area 5202 is a display device equipped with the light-emitting device described in Embodiment 1, which is provided on the pillar. By displaying images from an imaging means provided on the vehicle body on the display area 5202, the field of view obstructed by the pillar can be compensated for. Similarly, the display area 5203 provided on the dashboard can compensate for the field of view obstructed by the vehicle body by displaying images from an imaging means provided on the outside of the vehicle, thereby compensating for blind spots and enhancing safety. By displaying images in a way that compensates for the parts that are not visible, safety checks can be performed more naturally and without discomfort.

[0405] Furthermore, display area 5203 can provide various information by displaying navigation information, driving speed or engine RPM, air conditioning settings, etc. The display items or layout can be changed as needed to suit the user's preferences. This information can also be provided in display areas 5200 to 5202. In addition, display areas 5200 to 5203 can also be used as lighting devices.

[0406] Figures 12(A) and 12(B) also show a foldable portable information terminal 5150. The foldable portable information terminal 5150 has a housing 5151, a display area 5152, and a bending portion 5153. Figure 12(A) shows the portable information terminal 5150 in its unfolded state. Figure 12(B) shows the portable information terminal in its folded state. Despite having a large display area 5152, the portable information terminal 5150 is compact and highly portable when folded.

[0407] The display area 5152 can be folded in half by the bending portion 5153. The bending portion 5153 is composed of an expandable member and a plurality of support members. When folded, the expandable member extends, and the bending portion 5153 folds to have a radius of curvature of 2 mm or more, preferably 3 mm or more.

[0408] The display area 5152 may also be a touch panel (input / output device) equipped with a touch sensor (input device). A light-emitting device according to one aspect of the present invention can be used in the display area 5152.

[0409] Figures 13(A) to 13(C) also show the foldable portable information terminal 9310. Figure 13(A) shows the portable information terminal 9310 in its unfolded state. Figure 13(B) shows the portable information terminal 9310 in an intermediate state, transitioning from either the unfolded or folded state to the other. Figure 13(C) shows the portable information terminal 9310 in its folded state. The portable information terminal 9310 offers excellent portability in its folded state and excellent readability of the display due to its seamless, wide display area in its unfolded state.

[0410] The display panel 9311 is supported by three housings 9315 connected by a hinge 9313. The display panel 9311 may also be a touch panel (input / output device) equipped with a touch sensor (input device). Furthermore, the display panel 9311 can be reversibly transformed from an unfolded state to a folded state by bending the two housings 9315 via the hinge 9313. A light-emitting device according to one aspect of the present invention can be used in the display panel 9311. [Examples]

[0411] In this embodiment, we describe light-emitting devices (light-emitting devices 1 to 8) having at least three layers in the hole transport region, in which the combination of high and low refractive indices in the three layers is changed. The structural formulas of the organic compounds used in this embodiment are shown below.

[0412] [ka]

[0413] (Method for fabricating light-emitting device 1) First, a 100 nm thick film of silver (Ag) was deposited on a glass substrate as a reflective electrode using sputtering. Then, a 10 nm thick film of indium tin oxide (ITSO) containing silicon oxide was deposited on a transparent electrode using sputtering, forming the first electrode 101. The electrode area was 4 mm². 2 The dimensions were set to (2mm x 2mm). The first electrode 101 is a transparent electrode and can be considered as the first electrode together with the reflective electrode mentioned above.

[0414] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0415] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus where the internal pressure was reduced to approximately Pa. After vacuum firing at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0416] Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 is formed faces downwards. Then, a hole injection layer 111 is formed on the first electrode 101 by co-depositing 4,4'-bis(dibenzothiophen-4-yl)-4''-(9-phenyl-9H-carbazole-2-yl)triphenylamine (abbreviated as PCBDBtBB-02), represented by the above structural formula (i), and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672, in a weight ratio of 1:0.1 (=PCBDBtBB-02:OCHD-003) to a thickness of 10 nm using a vapor deposition method.

[0417] On the hole injection layer 111, a hole transport layer 112 was formed by depositing a 35 nm layer of N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as mmtBumTPoFBi-02), represented by the above structural formula (viii), as a first layer, a 40 nm layer of PCBDBtBB-02, and a 35 nm layer of mmtBumTPoFBi-02.

[0418] Next, PCBDBtBB-02 was deposited onto the hole transport layer 112 to a thickness of 10 nm to form an electron blocking layer.

[0419] Subsequently, 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (abbreviated as Bnf(II)PhA), represented by the above structural formula (ii), and 3,10-bis[N-(9-phenyl-9H-carbazole-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10PCA2Nbf(IV)-02), represented by the above structural formula (iii), were co-deposited at a weight ratio of 1:0.015 (=Bnf(II)PhA:3,10PCA2Nbf(IV)-02) at a density of 25 nm to form an emissive layer 113.

[0420] Subsequently, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mFBPTzn), represented by the above structural formula (iv), was deposited to a thickness of 10 nm to form a hole blocking layer. Then, 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenantrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mPn-mDMePyPTzn), represented by the above structural formula (v), and 8-hydroxyquinolinatolithium (abbreviated as Liq), represented by the above structural formula (vi), were co-deposited at a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to a thickness of 20 nm to form an electron transport layer 114.

[0421] After forming the electron transport layer 114, a lithium fluoride (LiF) film was deposited to a thickness of 1 nm to form an electron injection layer 115. Finally, a second electrode 102 was formed by co-depositing silver (Ag) and magnesium (Mg) in a volume ratio of 1:0.1 and a film thickness of 15 nm to fabricate the light-emitting device 1. This is a semi-transmissive / semi-reflective electrode having both light-reflecting and light-transmitting functions, and the light-emitting device in this embodiment is a top-emission type element that extracts light from the second electrode 102. In addition, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviated as DBT3P-II), represented by the above structural formula (vii), was deposited on the second electrode 102 to a thickness of 70 nm to improve extraction efficiency.

[0422] (Method for fabricating comparative light-emitting device 1) Comparative light-emitting device 1 was fabricated in the same manner as light-emitting device 1, except that the first and third layers in the hole transport layer were replaced with PCBDBtBB-02 and their respective film thicknesses were set to 30 nm.

[0423] (Method for fabricating comparative light-emitting device 2) Comparative light-emitting device 2 was fabricated in the same manner as light-emitting device 1, except that the second layer in the hole transport layer of light-emitting device 1 was replaced with mmtBumTPoFBi-02 and its film thickness was set to 60 nm.

[0424] The element structures of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2 are summarized in the table below.

[0425] [Table 1]

[0426] [Table 2]

[0427] Furthermore, Figure 17 shows the results of measuring the ordinary refractive index of PCBDBtBB-02 and mmtBumTPoFBi-02. The measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woolam Japan). For the measurement samples, films were used in which each layer material was deposited on a quartz substrate by vacuum deposition, with a thickness of approximately 50 nm.

[0428] From the figure, it can be seen that PCBDBtBB-02 and mmtBumTPoFBi-02 are combinations where the difference between them is between 0.2 and less than 0.5 in the range from 450nm to 650nm.

[0429] Furthermore, the HOMO levels of PCBDBtBB-02 and mmtBumTPoFBi-02, calculated from cyclic voltammetry (CV) measurements, were -5.51 eV and -5.43 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. This indicates that the difference in HOMO levels between PCBDBtBB-02 and mmtBumTPoFBi-02 is less than 0.1 eV. For the CV measurements, an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS Model 600A or 600C) was used to measure solutions of the materials dissolved in the solvent.

[0430] The above-mentioned light-emitting device and comparative light-emitting device were sealed with a glass substrate in a glove box under a nitrogen atmosphere to prevent exposure to the atmosphere (application of UV-curable sealant around the element, irradiation of only the sealant with UV light without irradiating the light-emitting device, and heat treatment at 80°C for 1 hour under atmospheric pressure). After this, the initial characteristics of these light-emitting devices were measured.

[0431] Figure 18 shows the luminance-current density characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2; Figure 19 shows the luminance-voltage characteristics; Figure 20 shows the current efficiency-luminance characteristics; Figure 21 shows the current density-voltage characteristics; Figure 22 shows the blue index-luminance characteristics; and Figure 23 shows the emission spectra. Furthermore, the luminance characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2 at 1000 cd / m² are also shown. 2Table 3 shows the main characteristics of the vicinity. Luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (Topcon SR-UL1R) at room temperature.

[0432] The Blue Index (BI) is a value obtained by dividing the current efficiency (cd / A) by the chromaticity y (cd / A / y), and is one of the indicators that represent the emission characteristics of blue light. Blue light tends to have higher color purity as the chromaticity y decreases. High-purity blue light can express a wide range of blue colors even with a small luminance component, and by using high-purity blue light, the required luminance to express blue decreases, resulting in a reduction in power consumption. Therefore, BI, which takes into account chromaticity y as one of the indicators of blue purity, is suitably used as a means of representing the efficiency of blue light, and it can be said that light-emitting devices with a high BI are more efficient as blue light-emitting devices used in displays.

[0433] [Table 3]

[0434] Figures 18 to 23 and Table 3 show that the light-emitting device 1, which is a light-emitting device according to one embodiment of the present invention, is a light-emitting device with good current efficiency and blue index (BI) compared to other light-emitting devices. In particular, the BI is very high at 200 (cd / A / y) or more, so light-emitting device 1 can be said to be a light-emitting device with particularly good BI. For this reason, one embodiment of the present invention is particularly suitable for light-emitting devices used in displays. [Examples]

[0435] In this embodiment, a light-emitting device 10, which is a light-emitting device according to one aspect of the present invention, and a comparative light-emitting device 10, which is a comparative light-emitting device, will be described. The structural formulas of the organic compounds used in this embodiment are shown below.

[0436] [ka]

[0437] (Method for fabricating the light-emitting device 10) First, a 100 nm thick film of silver (Ag) was deposited on a glass substrate as a reflective electrode using sputtering. Then, a 10 nm thick film of indium tin oxide (ITSO) containing silicon oxide was deposited on a transparent electrode using sputtering, forming the first electrode 101. The electrode area was 4 mm². 2 The dimensions were set to (2mm x 2mm). The first electrode 101 is a transparent electrode and can be considered as the first electrode together with the reflective electrode mentioned above.

[0438] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0439] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus where the internal pressure was reduced to approximately Pa. After vacuum firing at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0440] Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 is formed faces downwards. Then, a hole injection layer 111 is formed on the first electrode 101 by co-depositing N-3',5'-ditterybutyl-1,1'-biphenyl-4-yl-N-1,1'-biphenyl-2-yl-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi), represented by the above structural formula (ix), and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672, in a weight ratio of 1:0.1 (=mmtBuBioFBi:OCHD-003) to a thickness of 10 nm.

[0441] On the hole injection layer 111, a hole transport layer 112 was formed by depositing 30 nm of mmtBuBioFBi as the first layer, 50 nm of 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviated as BBA(βN2)B-03), represented by the above structural formula (x), as the second layer, and 40 nm of mmtBuBioFBi as the third layer.

[0442] Next, an electron blocking layer was formed on the hole transport layer 112 by depositing N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviated as DBfBB1TP), represented by the above structural formula (xi), to a thickness of 10 nm.

[0443] Subsequently, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated as αN-βNPAnth), represented by the above structural formula (xii), and 3,10-bis[N-(9-phenyl-9H-carbazole-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10PCA2Nbf(IV)-02), represented by the above structural formula (iii), were co-deposited at a weight ratio of 1:0.015 (=αN-βNPAnth:3,10PCA2Nbf(IV)-02) at a density of 20 nm to form an emissive layer 113.

[0444] Subsequently, 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), represented by the above structural formula (xiv), was deposited to a thickness of 10 nm to form a hole block layer. Then, 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenantrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mPn-mDMePyPTzn), represented by the above structural formula (v), and 8-hydroxyquinolinatolithium (abbreviated as Liq), represented by the above structural formula (vi), were co-deposited at a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0445] After forming the electron transport layer 114, a lithium fluoride (LiF) film was deposited to a thickness of 1 nm to form an electron injection layer 115. Finally, a second electrode 102 was formed by co-depositing silver (Ag) and magnesium (Mg) in a volume ratio of 1:0.1 and a film thickness of 15 nm to fabricate the light-emitting device 10. This is a semi-transmissive / semi-reflective electrode having both light-reflecting and light-transmitting functions, and the light-emitting device in this embodiment is a top-emission type element that extracts light from the second electrode 102. In addition, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviated as DBT3P-II), represented by the above structural formula (vii), was deposited on the second electrode 102 to a thickness of 70 nm to improve extraction efficiency.

[0446] (Method for fabricating the comparative light-emitting device 10) The comparative light-emitting device 10 was fabricated in the same manner as the light-emitting device 10, except that the thickness of the first layer in the hole transport layer was set to 35 nm and the second layer was formed with mmtBuBioFBi.

[0447] The element structures of the light-emitting device 10 and the comparative light-emitting device 10 are summarized in the table below.

[0448] [Table 4]

[0449] Furthermore, Figure 24 shows the results of measuring the paraphotometric refractive index of BBA(βN2)B-03 and mmtBuBioFBi. The measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woolam Japan). For the measurement samples, films were used in which each layer of material was deposited on a quartz substrate by vacuum deposition, with a thickness of approximately 50 nm.

[0450] From the figure, it can be seen that BBA(βN2)B-03 and mmtBuBioFBi are a combination in which the difference between them is between 0.2 and less than 0.5 in the range from 450nm to 650nm.

[0451] Furthermore, the HOMO levels of BBA(βN2)B-03 and mmtBuBioFBi, calculated from cyclic voltammetry (CV) measurements, were -5.47 eV and -5.42 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. This indicates that the difference in HOMO levels between BBA(βN2)B-03 and mmtBuBioFBi is less than 0.1 eV. For the CV measurements, an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS Model 600A or 600C) was used to measure solutions prepared by dissolving the materials in the solvent.

[0452] The above-mentioned light-emitting device and comparative light-emitting device were sealed with a glass substrate in a glove box under a nitrogen atmosphere to prevent exposure to the atmosphere (application of UV-curable sealant around the element, irradiation of only the sealant with UV light without irradiating the light-emitting device, and heat treatment at 80°C for 1 hour under atmospheric pressure). After this, the initial characteristics of these light-emitting devices were measured.

[0453] Figure 25 shows the luminance-current density characteristics of the light-emitting device 10 and the comparative light-emitting device 10, Figure 26 shows the luminance-voltage characteristics, Figure 27 shows the current efficiency-luminance characteristics, Figure 28 shows the current density-voltage characteristics, Figure 29 shows the blue index-current density characteristics, Figure 30 shows the emission spectrum, and Figure 31 shows the viewing angle characteristics. In addition, the luminance of the light-emitting device 10 and the comparative light-emitting device 10 at 1000 cd / m² is shown. 2 Table 5 shows the main characteristics in the vicinity. Brightness, CIE chromaticity, and emission spectra were measured using a spectroradiometer (Topcon SR-UL1R) at room temperature. For the field of view characteristics, the emission spectra were measured at 10° intervals from -80° to 80°, with the direction perpendicular to the light-emitting surface of the light-emitting device set as 0°, and the photon intensity ratio of the light-emitting element at each angle was obtained. A multi-channel spectrometer (Hamamatsu Photonics PMA-12) was used for the measurements.

[0454] [Table 5]

[0455] Figures 25 to 31 and Table 5 show that the light-emitting device 10 according to one embodiment of the present invention is a light-emitting device with good current efficiency and blue index (BI). In particular, the BI is very high at 200 (cd / A / y) or more, so the light-emitting device 10 can be said to be a light-emitting device with particularly good BI. For this reason, one embodiment of the present invention is particularly suitable for use as a light-emitting device in displays.

[0456] Furthermore, Figure 31 shows that there is almost no difference in the viewing angle characteristics between the light-emitting device 10 and the comparative light-emitting device 10. Therefore, according to one aspect of the present invention, the efficiency of the light-emitting device can be increased without changing the viewing angle characteristics.

[0457] Furthermore, the current density is 50 mA / cm². 2 Figure 32 shows a graph representing the change in brightness with respect to operating time. It was found that the light-emitting device 10 according to one aspect of the present invention is a more reliable light-emitting device compared to the comparative light-emitting device 10. [Examples]

[0458] In this embodiment, a light-emitting device 20, which is a light-emitting device according to one aspect of the present invention, will be described. The structural formula of the organic compound used in this embodiment is shown below.

[0459] [ka]

[0460] (Method for fabricating the light-emitting device 20) First, a 100 nm thick film of silver (Ag) was deposited on a glass substrate as a reflective electrode using sputtering. Then, a 10 nm thick film of indium tin oxide (ITSO) containing silicon oxide was deposited on a transparent electrode using sputtering, forming the first electrode 101. The electrode area was 4 mm². 2 The dimensions were set to (2mm x 2mm). The first electrode 101 is a transparent electrode and can be considered as the first electrode together with the reflective electrode mentioned above.

[0461] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0462] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus where the internal pressure was reduced to approximately Pa. After vacuum firing at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0463] Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 is formed faces downwards. Then, a hole injection layer 111 is formed on the first electrode 101 by co-depositing N-3',5'-ditterybutyl-1,1'-biphenyl-4-yl-N-1,1'-biphenyl-2-yl-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi), represented by the above structural formula (ix), and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672, in a weight ratio of 1:0.04 (=mmtBuBioFBi:OCHD-003) to a thickness of 10 nm.

[0464] On the hole injection layer 111, a hole transport layer 112 was formed by depositing mmtBuBioFBi at a first layer of 35 nm, 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviated as BBA(βN2)B-03), represented by the above structural formula (x), at a second layer of 50 nm, and mmtBuBioFBi at a third layer of 40 nm.

[0465] Next, an electron blocking layer was formed on the hole transport layer 112 by depositing N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviated as DBfBB1TP), represented by the above structural formula (xi), to a thickness of 10 nm.

[0466] Subsequently, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated as αN-βNPAnth), represented by the above structural formula (xii), and 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazavolin-7-amine (abbreviated as DPhA-tBu4DABNA), represented by the above structural formula (xiii), were co-deposited at a weight ratio of 1:0.015 (=αN-βNPAnth:DPhA-tBu4DABNA) at a density of 20 nm to form an emissive layer 113.

[0467] Subsequently, 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), represented by the above structural formula (xiv), was deposited to a thickness of 5 nm to form a hole blocking layer. Then, 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), represented by the above structural formula (xv), was deposited to a thickness of 5 nm to form an electron transport layer 114.

[0468] After forming the electron transport layer 114, an electron injection layer 115 was formed by co-depositing bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (xvi), and lithium fluoride (LiF) at a volume ratio of 1:3 (=BPhen:LiF) to a thickness of 27 nm. Finally, a second electrode 102 was formed by co-depositing silver (Ag) and magnesium (Mg) at a volume ratio of 1:0.1 and a film thickness of 15 nm to fabricate the light-emitting device 20. This is a semi-transmissive / semi-reflective electrode having both light-reflecting and light-transmitting functions, and the light-emitting device in this embodiment is a top-emission type element that extracts light from the second electrode 102. Furthermore, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviated as DBT3P-II), represented by the above structural formula (vii), was deposited at a thickness of 70 nm on the second electrode 102 to improve the extraction efficiency.

[0469] The element structure of the light-emitting device 20 is summarized in the table below.

[0470] [Table 6]

[0471] Furthermore, Figure 24 shows the results of measuring the paraphotometric refractive index of BBA(βN2)B-03 and mmtBuBioFBi. The measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woolam Japan). For the measurement samples, films were used in which each layer of material was deposited on a quartz substrate by vacuum deposition, with a thickness of approximately 50 nm.

[0472] From the figure, it can be seen that BBA(βN2)B-03 and mmtBuBioFBi are a combination in which the difference between them is between 0.2 and less than 0.5 in the range from 450nm to 650nm.

[0473] Furthermore, the HOMO levels of BBA(βN2)B-03 and mmtBuBioFBi, calculated from cyclic voltammetry (CV) measurements, were -5.47 eV and -5.42 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. This indicates that the difference in HOMO levels between BBA(βN2)B-03 and mmtBuBioFBi is less than 0.1 eV. For the CV measurements, an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS Model 600A or 600C) was used to measure solutions prepared by dissolving the materials in the solvent.

[0474] The above-mentioned light-emitting devices were sealed with a glass substrate in a glove box under a nitrogen atmosphere to prevent exposure to the atmosphere (application of a UV-curable sealant around the element, irradiation of only the sealant with UV light without irradiating the light-emitting device, and heat treatment at 80°C for 1 hour under atmospheric pressure). After this, the initial characteristics of these light-emitting devices were measured.

[0475] Figure 33 shows the luminance-current density characteristics of the light-emitting device 20, Figure 34 shows the luminance-voltage characteristics, Figure 35 shows the current efficiency-luminance characteristics, Figure 36 shows the current density-voltage characteristics, Figure 37 shows the blue index-luminance characteristics, and Figure 38 shows the emission spectrum. 2 Table 7 shows the main characteristics of the vicinity. Luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (Topcon SR-UL1R) at room temperature.

[0476] [Table 7]

[0477] Figures 33 to 38 and Table 7 show that the light-emitting device 20 of one embodiment of the present invention is a light-emitting device that exhibits very good current efficiency and blue index (BI). In particular, the BI is very high at 250 (cd / A / y) or more, so the light-emitting device 20 can be said to be a light-emitting device with particularly good BI. For this reason, one embodiment of the present invention is particularly suitable for use as a light-emitting device in displays.

[0478] Furthermore, the current density is 50 mA / cm². 2 Figure 39 shows a graph representing the change in brightness with respect to the operating time. It was found that the light-emitting device 20 according to one aspect of the present invention is a reliable light-emitting device. [Examples]

[0479] In this embodiment, a light-emitting device 30, which is a light-emitting device according to one aspect of the present invention, will be described. The structural formula of the organic compound used in this embodiment is shown below.

[0480] [ka]

[0481] (Method for fabricating the light-emitting device 30) First, a 100 nm thick film of silver (Ag) was deposited on a glass substrate as a reflective electrode using sputtering. Then, a 5 nm thick film of indium tin oxide (ITSO) containing silicon oxide was deposited on a transparent electrode using sputtering to form the first electrode 101. The electrode area was 4 mm². 2 The dimensions were set to (2mm x 2mm). The first electrode 101 is a transparent electrode and can be considered as the first electrode together with the reflective electrode mentioned above.

[0482] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0483] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus where the internal pressure was reduced to approximately Pa. After vacuum firing at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0484] Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 is formed faces downwards. Then, a hole injection layer 111 is formed on the first electrode 101 by co-depositing N-3',5'-ditterybutyl-1,1'-biphenyl-4-yl-N-1,1'-biphenyl-2-yl-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi), represented by the above structural formula (ix), and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672, in a weight ratio of 1:0.1 (=mmtBuBioFBi:OCHD-003) to a thickness of 10 nm.

[0485] On the hole injection layer 111, a hole transport layer 112 was formed by depositing mmtBuBioFBi at a first layer of 42.5 nm, 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviated as BBA(βN2)B-03), represented by the above structural formula (x), at a second layer of 50 nm, and mmtBuBioFBi at a third layer of 40 nm.

[0486] Next, an electron blocking layer was formed on the hole transport layer 112 by depositing N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviated as DBfBB1TP), represented by the above structural formula (xi), to a thickness of 10 nm.

[0487] Subsequently, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated as αN-βNPAnth), represented by the above structural formula (xii), and 3,10-bis[N-(9-phenyl-9H-carbazole-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10PCA2Nbf(IV)-02), represented by the above structural formula (iii), were co-deposited at a weight ratio of 1:0.015 (=αN-βNPAnth:3,10PCA2Nbf(IV)-02) at a density of 20 nm to form an emissive layer 113.

[0488] Next, 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), represented by the above structural formula (xiv), was deposited to a thickness of 10 nm to form a hole block layer. Then, 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenantrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mPn-mDMePyPTzn), represented by the above structural formula (v), and 8-hydroxyquinolinatolithium (abbreviated as Liq), represented by the above structural formula (vi), were co-deposited to a thickness of 20 nm in a weight ratio of 0.4:0.6 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0489] After forming the electron transport layer 114, a lithium fluoride (LiF) film was deposited to a thickness of 1 nm to form an electron injection layer 115. Finally, a second electrode 102 was formed by co-depositing silver (Ag) and magnesium (Mg) in a volume ratio of 1:0.1 and a film thickness of 15 nm to fabricate the light-emitting device 30. This is a semi-transmissive / semi-reflective electrode having both light-reflecting and light-transmitting functions, and the light-emitting device in this embodiment is a top-emission type element that extracts light from the second electrode 102. In addition, an organic compound was deposited on the second electrode 102 as a cap layer at a thickness of 65 nm to improve extraction efficiency.

[0490] The element structure of the light-emitting device 30 is summarized in the table below.

[0491] [Table 8]

[0492] Furthermore, Figure 24 shows the results of measuring the paraphotometric refractive index of BBA(βN2)B-03 and mmtBuBioFBi. The measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woolam Japan). For the measurement samples, films were used in which each layer of material was deposited on a quartz substrate by vacuum deposition, with a thickness of approximately 50 nm.

[0493] From the figure, it can be seen that BBA(βN2)B-03 and mmtBuBioFBi are a combination in which the difference between them is between 0.2 and less than 0.5 in the range from 450nm to 650nm.

[0494] Furthermore, the HOMO levels of BBA(βN2)B-03 and mmtBuBioFBi, calculated from cyclic voltammetry (CV) measurements, were -5.47 eV and -5.42 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. This indicates that the difference in HOMO levels between BBA(βN2)B-03 and mmtBuBioFBi is less than 0.1 eV. For the CV measurements, an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS Model 600A or 600C) was used to measure solutions prepared by dissolving the materials in the solvent.

[0495] The above-mentioned light-emitting devices were sealed with a glass substrate in a glove box under a nitrogen atmosphere to prevent exposure to the atmosphere (application of a UV-curable sealant around the element, irradiation of only the sealant with UV light without irradiating the light-emitting device, and heat treatment at 80°C for 1 hour under atmospheric pressure). After this, the initial characteristics of these light-emitting devices were measured.

[0496] Figure 40 shows the luminance-current density characteristics of the light-emitting device 30, Figure 41 shows the luminance-voltage characteristics, Figure 42 shows the current efficiency-luminance characteristics, Figure 43 shows the current density-voltage characteristics, Figure 44 shows the blue index-current density characteristics, and Figure 45 shows the emission spectrum. Furthermore, the luminance of the light-emitting device 30 at 1000 cd / m² is also shown. 2 Table 9 shows the main characteristics of the vicinity. Brightness, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (Topcon SR-UL1R) at room temperature.

[0497] [Table 9]

[0498] Figures 40 to 45 and Table 9 show that the light-emitting device 30 according to one embodiment of the present invention is a light-emitting device with good current efficiency and blue index (BI). In particular, the BI is very high at 200 (cd / A / y) or more, so the light-emitting device 30 can be said to be a light-emitting device with particularly good BI. For this reason, one embodiment of the present invention is particularly suitable for use as a light-emitting device in displays.

[0499] Furthermore, the current density is 50 mA / cm². 2 Figure 46 shows a graph representing the change in brightness with respect to operating time. It was found that the light-emitting device 30 according to one aspect of the present invention is a reliable light-emitting device. [Examples]

[0500] In this example, we describe light-emitting devices 40 and 41 in which the GSP values ​​in the first hole transport layer, second hole transport layer, and third hole transport layer have different sequences. The structural formulas of the organic compounds used in this example are shown below.

[0501] [ka]

[0502] (Method for fabricating the light-emitting device 40) First, a 100 nm thick film of silver (Ag) was deposited on a glass substrate as a reflective electrode using sputtering. Then, a 5 nm thick film of indium tin oxide (ITSO) containing silicon oxide was deposited on a transparent electrode using sputtering to form the first electrode 101. The electrode area was 4 mm². 2 The dimensions were set to (2mm x 2mm). The first electrode 101 is a transparent electrode and can be considered as the first electrode together with the reflective electrode mentioned above.

[0503] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0504] Then, 10-4 The substrate was introduced into a vacuum deposition apparatus where the internal pressure was reduced to approximately Pa. After vacuum firing at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0505] Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 is formed faces downwards. Then, a hole injection layer 111 is formed on the first electrode 101 by co-depositing N-3',5'-ditterybutyl-1,1'-biphenyl-4-yl-N-1,1'-biphenyl-2-yl-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi), represented by the above structural formula (ix), and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672, in a weight ratio of 1:0.1 (=mmtBuBioFBi:OCHD-003) to a thickness of 10 nm.

[0506] On the hole injection layer 111, a hole transport layer 112 was formed by depositing 40 nm of mmtBuBioFBi as the first layer, 50 nm of 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviated as BBA(βN2)B-03), represented by the above structural formula (x), as the second layer, and 40 nm of mmtBuBioFBi as the third layer.

[0507] Next, an electron blocking layer was formed on the hole transport layer 112 by depositing N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviated as DBfBB1TP), represented by the above structural formula (xi), to a thickness of 10 nm.

[0508] Subsequently, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated as αN-βNPAnth), represented by the above structural formula (xii), and 3,10-bis[N-(9-phenyl-9H-carbazole-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10PCA2Nbf(IV)-02), represented by the above structural formula (iii), were co-deposited at a weight ratio of 1:0.015 (=αN-βNPAnth:3,10PCA2Nbf(IV)-02) at a density of 20 nm to form an emissive layer 113.

[0509] Subsequently, 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), represented by the above structural formula (xiv), was deposited to a thickness of 10 nm to form a hole block layer. Then, 2-{(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mmtBumBPTzn), represented by the above structural formula (xix), and 6-methyl-8-quinolinolato-lithium (abbreviated as Li-6mq), represented by the above structural formula (xx), were co-deposited at a weight ratio of 1:1 (=mmtBumBPTzn:Li-6mq) to a thickness of 20 nm to form an electron transport layer 114.

[0510] After forming the electron transport layer 114, a lithium fluoride (LiF) film was deposited to a thickness of 1 nm to form an electron injection layer 115. Finally, a second electrode 102 was formed by co-depositing silver (Ag) and magnesium (Mg) in a volume ratio of 1:0.1 and a film thickness of 15 nm to fabricate the light-emitting device 40. The second electrode is a semi-transmissive / semi-reflective electrode having both light-reflecting and light-transmitting functions, and the light-emitting device in this embodiment is a top-emission type element that extracts light from the second electrode 102. In addition, a cap layer made of an organic compound was deposited on the second electrode 102 to a thickness of 65 nm to improve extraction efficiency.

[0511] (Method for fabricating the light-emitting device 41) The light-emitting device 41 was fabricated in the same manner as the light-emitting device 40, except that the first layer in the hole transport layer 112 of the light-emitting device 40 was formed with N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-N-(1,1'-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-04), represented by the above structural formula (xviii), and the film thickness was deposited to 52.5 nm.

[0512] (Method for fabricating the comparative light-emitting device 40) The comparative light-emitting device 40 was fabricated in the same manner as light-emitting device 40 or light-emitting device 41, except that the hole transport layer 112 was fabricated by depositing mmtBuBioFBi to a thickness of 130 nm.

[0513] The element structures of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40 are summarized in the table below.

[0514] [Table 10]

[0515] [Table 11]

[0516] Furthermore, the results of measuring the paraphotometric refractive index of mmtBuBioFBi, BBA(βN2)B-03, and mmtBumTPoFBi-04 are shown in Figures 47(A) and (B). The measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woolam Japan). For the measurement samples, films were used in which each layer of material was deposited on a quartz substrate by vacuum deposition to a thickness of approximately 50 nm.

[0517] From the figure, it can be seen that BBA(βN2)B-03 and mmtBuBioFBi, and BBA(βN2)B-03 and mmtBumTPoFBi-04 are combinations in which the difference in refractive index is between 0.2 and less than 0.5 in the range from 450nm to 650nm.

[0518] Furthermore, the HOMO levels of BBA(βN2)B-03, mmtBuBioFBi, and mmtBumTPoFBi-04, calculated from cyclic voltammetry (CV) measurements, were -5.47 eV, -5.42 eV, and -5.42 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. This indicates that the difference in HOMO levels between BBA(βN2)B-03 and mmtBuBioFBi, and between BBA(βN2)B-03 and mmtBumTPoFBi-04, is less than 0.1 eV. For the CV measurements, an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS Model 600A or 600C) was used to measure solutions of the materials dissolved in the solvent.

[0519] Furthermore, the GSPs of mmtBuBioFBi, BBA(βN2)B-03, and mmtBumTPoFBi-04 are as shown in the table below. From the table below, it can be seen that light-emitting device 40 is a device fabricated without considering GSP, while light-emitting device 41 is a light-emitting device fabricated with GSP in mind, as the GSP of the third layer is the largest value, and the value obtained by subtracting the GSP of the second layer from the GSP of the first layer is 10 (mV / nm) or less.

[0520] [Table 12]

[0521] The above-mentioned light-emitting devices were sealed with a glass substrate in a glove box under a nitrogen atmosphere to prevent exposure to the atmosphere (application of a UV-curable sealant around the element, irradiation of only the sealant with UV light without irradiating the light-emitting device, and heat treatment at 80°C for 1 hour under atmospheric pressure). After this, the initial characteristics of these light-emitting devices were measured.

[0522] Figure 48 shows the luminance-current density characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40; Figure 49 shows the current efficiency-luminance characteristics; Figure 50 shows the luminance-voltage characteristics; Figure 51 shows the current density-voltage characteristics; Figure 52 shows the blue index-luminance characteristics; Figure 53 shows the power efficiency-luminance characteristics; and Figure 54 shows the emission spectra of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40 at 1000 cd / m². 2 Table 13 shows the main characteristics in the vicinity. Luminance, CIE chromaticity, and emission spectra were measured using a spectroradiometer (Topcon SR-UL1R) at room temperature. Power efficiency was calculated assuming a Lambertsian curve.

[0523] [Table 13]

[0524] Figures 48 to 54 and Table 13 show that the light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40 according to one embodiment of the present invention are all light-emitting devices with good characteristics. In particular, it can be seen that the light-emitting device 40 and light-emitting device 41 having the configuration of the present invention have good current efficiency and BI because the hole transport layer is composed of a first to a third layer.

[0525] Comparing the light-emitting device 40 with the comparative light-emitting device 40, it can be seen that the driving voltage of the light-emitting device 40 is increased due to the influence of interfacial resistance and other factors resulting from the three-layer structure of the hole transport layer 112. However, because the current efficiency improvement effect of this structure is significant, the power efficiency of the light-emitting device 40 is higher than that of the comparative light-emitting device 40 even though the driving voltage is increased.

[0526] On the other hand, the light-emitting device 41, which has a first to third layer formed with GSP in mind, has a low driving voltage despite having a three-layer hole transport layer 112, and shows a lower value than the comparative light-emitting device 40, which has only one hole transport layer. As a result, it was found that the light-emitting device 41 is a light-emitting device that exhibits very good power efficiency.

[0527] Furthermore, the current density is 50 mA / cm². 2 Figure 55 shows a graph representing the change in brightness with respect to operating time. It was found that the light-emitting devices 40 and 41 of one aspect of the present invention are more reliable light-emitting devices than the comparative light-emitting device 40. [Examples]

[0528] In this example, we describe light-emitting devices 50 and 51 in which the GSP values ​​in the first hole transport layer, second hole transport layer, and third hole transport layer have different sequences. The structural formulas of the organic compounds used in this example are shown below.

[0529] [ka]

[0530] (Method for fabricating the light-emitting device 50) First, a 100 nm thick film of silver (Ag) was deposited on a glass substrate as a reflective electrode using sputtering. Then, a 10 nm thick film of indium tin oxide (ITSO) containing silicon oxide was deposited on a transparent electrode using sputtering, forming the first electrode 101. The electrode area was 4 mm². 2 The dimensions were set to (2mm x 2mm). The first electrode 101 is a transparent electrode and can be considered as the first electrode together with the reflective electrode mentioned above.

[0531] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0532] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus where the internal pressure was reduced to approximately Pa. After vacuum firing at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0533] Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 is formed faces downwards. Then, a hole injection layer 111 is formed on the first electrode 101 by co-depositing N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-N-(1,1'-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as mmtBumTPoFBi-04), represented by the above structural formula (xviii), and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672, in a weight ratio of 1:0.1 (=mmtBumTPoFBi-04:OCHD-003) to a thickness of 10 nm.

[0534] On the hole injection layer 111, a hole transport layer 112 was formed by depositing mmtBumTPoFBi-04 as a first layer at a depth of 50 nm, 3-(dibenzothiophen-4-yl)-4'-phenyl-4''-(9-phenyl-9H-carbazole-2-yl)triphenylamine (abbreviated as PCBBiPDBt-02), represented by the above structural formula (xxi), at a depth of 50 nm, and N-(3',5'-di-tert-butyl-1,1'-biphenyl-4-yl)-bis(9,9-dimethyl-9H-fluorene)-2,2'-amine (abbreviated as mmtBuBiFF), represented by the above structural formula (xxii), at a depth of 50 nm.

[0535] Subsequently, 11-(4-[1,1'-diphenyl]-4-yl-6-phenyl-1,3,5-triazine-2-yl)-11,12-dihydro-12-phenyl-indoro[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn) represented by the above structural formula (xxiii), and 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) represented by the above structural formula (xxiv), and the above structural formula ( A light-emitting layer 113 was formed by co-depositing [2-d3-methyl-(2-pyridinyl-κN)benzofl[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy-d3)), represented as xxv), at a weight ratio of 0.5:0.5:0.1 (=BP-Icz(II)Tzn:βNCCP:Ir(ppy)2(mbfpypy-d3)) at a density of 40 nm.

[0536] Subsequently, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mFBPTzn), represented by the above structural formula (iv), was deposited to a thickness of 10 nm to form a hole blocking layer. Then, 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenantrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mPn-mDMePyPTzn), represented by the above structural formula (v), and 8-hydroxyquinolinatolithium (abbreviated as Liq), represented by the above structural formula (vi), were co-deposited at a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0537] After forming the electron transport layer 114, a lithium fluoride (LiF) film was deposited to a thickness of 1 nm to form an electron injection layer 115. Finally, a second electrode 102 was formed by co-depositing silver (Ag) and magnesium (Mg) in a volume ratio of 1:0.1 and a film thickness of 15 nm to fabricate the light-emitting device 50. The second electrode is a semi-transmissive / semi-reflective electrode having both light-reflecting and light-transmitting functions, and the light-emitting device in this embodiment is a top-emission type element that extracts light from the second electrode 102. In addition, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviated as DBT3P-II), represented by the above structural formula (vii), was deposited on the second electrode 102 to a thickness of 70 nm to improve extraction efficiency.

[0538] (Method for fabricating the comparative light-emitting device 50) The comparative light-emitting device 50 was fabricated in the same manner as the light-emitting device 50, except that mmtBumTPoFBi-04 and PCBBiPDBt-02 were swapped.

[0539] The element structures of the light-emitting device 50 and the comparative light-emitting device 50 are summarized in the table below.

[0540] [Table 14]

[0541] Furthermore, the results of measuring the paraphoton refractive index of mmtBumTPoFBi-04, PCBBiPDBt-02, and mmtBuBiFF are shown in Figures 62(A) and (B). The measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woolam Japan). For the measurement samples, films were used in which each layer material was deposited on a quartz substrate by vacuum deposition to a thickness of approximately 50 nm.

[0542] The figure shows that the hole transport layer of light-emitting device 50 has a high refractive index in the second layer of its three layers, while the refractive indexes of the first and third layers are low. On the other hand, the comparative light-emitting device 50 has a high refractive index in the first layer of its three hole transport layers, while the refractive indexes of the second and third layers are low.

[0543] Furthermore, the HOMO levels of mmtBumTPoFBi-04, PCBBiPDBt-02, and mmtBuBiFF, calculated from cyclic voltammetry (CV) measurements, were -5.42 eV, -5.48 eV, and -5.33 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. This indicates that the difference in HOMO levels between mmtBumTPoFBi-04 and PCBBiPDBt-02, between PCBBiPDBt-02 and mmtBuBiFF, and between mmtBumTPoFBi-04 and mmtBuBiFF are all less than 0.2 eV. For CV measurements, an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS Model 600A or 600C) was used to measure solutions of the materials dissolved in the solvent.

[0544] Furthermore, the GSPs of mmtBumTPoFBi-04, PCBBiPDBt-02, and mmtBuBiFF are as shown in the table below. From the table below, it can be seen that light-emitting device 50 is a light-emitting device fabricated with GSP in mind, as the GSP of the third layer is the largest and the GSP of the first layer is the smallest. On the other hand, comparative light-emitting device 50 is a light-emitting device in which the GSP of the third layer is the largest, but the value obtained by subtracting the GSP of the second layer from the GSP of the first layer is 10 (mV / nm) or more.

[0545] [Table 15]

[0546] The above-mentioned light-emitting devices were sealed with a glass substrate in a glove box under a nitrogen atmosphere to prevent exposure to the atmosphere (application of a UV-curable sealant around the element, irradiation of only the sealant with UV light without irradiating the light-emitting device, and heat treatment at 80°C for 1 hour under atmospheric pressure). After this, the initial characteristics of these light-emitting devices were measured.

[0547] Figure 56 shows the luminance-current density characteristics of the light-emitting device 50 and the comparative light-emitting device 50, Figure 57 shows the luminance-voltage characteristics, Figure 58 shows the current efficiency-luminance characteristics, Figure 59 shows the current density-voltage characteristics, Figure 60 shows the power efficiency-luminance characteristics, and Figure 61 shows the emission spectra. Furthermore, the luminance of the light-emitting device 50 and the comparative light-emitting device 50 at 1000 cd / m² is also shown. 2 Table 16 shows the main characteristics in the vicinity. Luminance, CIE chromaticity, and emission spectra were measured using a spectroradiometer (Topcon SR-UL1R) at room temperature. Power efficiency was calculated assuming a Lambertsian coefficient.

[0548] [Table 16]

[0549] Figures 56 to 61 and Table 16 show that the light-emitting device 50 and comparative light-emitting device 50 according to one embodiment of the present invention are both light-emitting devices with good characteristics. In particular, the light-emitting device 50 having the configuration of the present invention is a light-emitting device with good current efficiency because the hole transport layer is composed of the first to third layers as shown in Embodiment 1. Furthermore, since the GSP of the first to third layers of the light-emitting device 50 is in the order of first layer < second layer < third layer, the driving voltage is low and the light-emitting device has very good power efficiency. [Examples]

[0550] In this embodiment, a light-emitting device 60, which is a light-emitting device according to one aspect of the present invention, will be described. The light-emitting device 60 is a tandem-type light-emitting device having multiple light-emitting layers separated by a charge-generating layer. The structural formula of the organic compound used in this embodiment is shown below.

[0551] [ka]

[0552] (Method for fabricating the light-emitting device 60) First, a 100 nm thick film of silver (Ag) was deposited on a glass substrate as a reflective electrode using sputtering. Then, a 5 nm thick film of indium tin oxide (ITSO) containing silicon oxide was deposited on a transparent electrode using sputtering to form the first electrode 101. The electrode area was 4 mm². 2 The dimensions were set to (2mm x 2mm). The transparent electrode functions as an anode and, together with the reflective electrode, can be considered as the first electrode 101.

[0553] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0554] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus where the internal pressure was reduced to approximately Pa. After vacuum firing at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0555] Next, the substrate was fixed to a holder provided in the vacuum deposition apparatus so that the surface on which the first electrode 101 was formed was facing downwards. On the first electrode 101, a hole injection layer was formed by co-depositing 10 nm of N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-N-(1,1'-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-04), represented by the above structural formula (xviii), and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672, in a weight ratio of 1:0.1 (=mmtBumTPoFBi-04:OCHD-003).

[0556] On the hole injection layer, a hole transport layer A was formed by depositing mmtBumTPoFBi-04 as the first layer at 35 nm, N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviated as DBfBB1TP), represented by the above structural formula (xi), at 50 nm as the second layer, and N-3',5'-diter-butyl-1,1'-biphenyl-4-yl-N-1,1'-biphenyl-2-yl-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as mmtBuBioFBi), represented by the above structural formula (ix), at 40 nm as the third layer.

[0557] Next, DBfBB1TP was deposited onto hole transport layer A to a thickness of 10 nm to form electron blocking layer A.

[0558] Subsequently, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated as αN-βNPAnth), represented by the above structural formula (xii), and 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazavolin-7-amine (abbreviated as DPhA-tBu4DABNA), represented by the above structural formula (xiii), were co-deposited at a weight ratio of 1:0.015 (=αN-βNPAnth:DPhA-tBu4DABNA) at a density of 20 nm to form an emissive layer A.

[0559] Next, 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), represented by the above structural formula (xiv), was deposited to a thickness of 10 nm to form a hole blocking layer A. Then, 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen), represented by the above structural formula (xv), was deposited to a thickness of 20 nm to form an electron transport layer A.

[0560] After forming electron transport layer A, lithium oxide (Li2O) was deposited at a depth of 0.1 nm, and then N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as PCBBiF), represented by the above structural formula (xxvii), and OCHD-003 were co-deposited at a depth of 10 nm in a weight ratio of 1:0.1 (=PCBBiF:OCHD-003) to form a charge generation layer.

[0561] A 40 nm layer of PCBBiF was deposited on the charge generation layer to form a hole transport layer B.

[0562] Next, DBfBB1TP was deposited onto the hole transport layer B to a thickness of 10 nm to form the electron blocking layer B.

[0563] Subsequently, αN-βNPAnth and DPhA-tBu4DABNA were co-deposited at a weight ratio of 1:0.015 (=αN-βNPAnth:DPhA-tBu4DABNA) at a density of 20 nm to form the light-emitting layer B.

[0564] Next, 6mBP-4Cz2PPm was deposited to a thickness of 10 nm to form hole block layer B, and electron transport layer B was formed by co-depositing 20 nm of 2-{(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mmtBumBPTzn), represented by the above structural formula (xix), and 6-methyl-8-quinolinolato-lithium (abbreviated as Li-6mq), represented by the above structural formula (xx), in a weight ratio of 1:1 (=mmtBumBPTzn:Li-6mq).

[0565] After forming the electron transport layer B, lithium fluoride (LiF) was deposited to a thickness of 2 nm to form the electron injection layer 115. Finally, a second electrode 102 was formed by co-depositing silver (Ag) and magnesium (Mg) in a volume ratio of 1:0.1 and a film thickness of 15 nm to fabricate the light-emitting device 60.

[0566] The second electrode 102 is a semi-transmissive / semi-reflective electrode having both light-reflecting and light-transmitting functions, and the light-emitting device in this embodiment is a top-emission type tandem element that extracts light from the second electrode 102. Furthermore, a 65 nm layer of 5,5'-diphenyl-2,2'-di-5H-[1]benzothieno[3,2-c]carbazole (abbreviated as BisBTc), represented by the above structural formula (xxvi), is deposited on the second electrode 102 as a cap layer to improve extraction efficiency.

[0567] The element structure of the light-emitting device 60 is summarized in the table below.

[0568] [Table 17]

[0569] Figures 63 and 64 show the results of measuring the refractive indices of mmtBumTPoFBi-04, DBfBB1TP, mmtBuBioFBi, mmtBumBPTzn, Li-6mq, and BisBTc. The measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woolam Japan). For the measurement samples, films were used in which each layer of material was deposited on a quartz substrate by vacuum deposition to a thickness of approximately 50 nm.

[0570] Figures 63 and 64 show that mmtBumTPoFBi-04, mmtBuBioFBi, mmtBumBPTzn, and Li-6mq are low refractive index materials with an ordinary refractive index of 1.50 to 1.75 across the entire wavelength range from 455 nm to 465 nm, while DBfBB1TP and BisBTc are high refractive index materials with an ordinary refractive index of 1.90 to 2.40 between 455 nm and 465 nm. Note that the light-emitting device 60 is a light-emitting device that emits blue light.

[0571] Furthermore, Figure 65 shows the emission spectrum of the luminescent material DPhA-tBu4DABNA in a toluene solution. From Figure 65, it can be seen that DPhA-tBu4DABNA is a luminescent material that exhibits emission with a narrow spectral width, with a full width at half maximum of 22 nm, a spectral width at 1 / e of maximum intensity of 29 nm, and energy values ​​of 0.13 eV and 0.17 eV, respectively.

[0572] The above-mentioned light-emitting devices 60 were sealed with a glass substrate in a glove box under a nitrogen atmosphere to prevent exposure to the atmosphere (application of a UV-curable sealant around the element, irradiation of only the sealant with UV light without irradiating the light-emitting device, and heat treatment at 80°C for 1 hour under atmospheric pressure). After this, the initial characteristics of these light-emitting devices were measured.

[0573] Figure 66 shows the luminance-current density characteristics of the light-emitting device 60, Figure 67 shows the current efficiency-luminance characteristics, Figure 68 shows the luminance-voltage characteristics, Figure 69 shows the current density-voltage characteristics, Figure 70 shows the blue index-luminance characteristics, and Figure 71 shows the emission spectrum. The current density is 10 mA / cm². 2 Table 18 shows the main characteristics of the vicinity. Brightness, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (Topcon SR-UL1R) at room temperature.

[0574] [Table 18]

[0575] From Figures 66 to 71 and Table 18, it can be seen that the light-emitting device 60 has a very high blue index (BI) of 458 (cd / A / y) or more, with a maximum value of 460 (cd / A / y), indicating that it is a light-emitting device that exhibits a very good blue index (BI). Therefore, one aspect of the present invention is particularly suitable for light-emitting devices used in displays.

[0576] ≪Reference synthesis example 1≫ This synthesis example describes the synthesis method for N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as mmtBumTPoFBi-02), which was used in Example 1. The structure of mmtBumTPoFBi-02 is shown below.

[0577] [ka]

[0578] <Step 1: Synthesis of 3-bromo-3',5,5'-tri-tert-butylbiphenyl> 37.2 g (128 mmol) of 1,3-dibromo-5-tert-butylbenzene, 20.0 g (85 mmol) of 3,5-di-tert-butylphenylboronic acid, 35.0 g (255 mmol) of potassium carbonate, 570 mL of toluene, 170 mL of ethanol, and 130 mL of tap water were placed in a three-necked flask. After degassing under reduced pressure, the flask was purged with nitrogen, and 382 mg (1.7 mmol) of palladium acetate (abbreviation: Pd(OAc)2) and 901 mg (3.4 mmol) of triphenylphosphine were added. The mixture was heated at 40°C for approximately 5 hours. After returning to room temperature, the organic layer and aqueous layer were separated. Magnesium sulfate was added to the organic layer to remove water and concentrate it. The resulting solution was purified by silica gel column chromatography to obtain 21.5 g of the target product, a colorless oil, in a yield of 63%. The synthesis scheme for Step 1 is shown in the following equation.

[0579] [ka]

[0580] <Step 2: Synthesis of 2-(3',5,5'-tri-tert-butyl[1,1'-biphenyl]-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane> In a three-necked flask, 15.0 g (38 mmol) of 3-bromo-3',5,5'-tri-tert-butylbiphenyl obtained in Step 1, 10.5 g (41 mmol) of 4,4,4',4',5,5,5',5-octamethyl-2,2'-bi-1,3,2-dioxaborolane, 11.0 g (113 mmol) of potassium acetate, and 125 mL of N,N-dimethylformamide (DMF) were placed. After degassing under reduced pressure, the flask was purged with nitrogen, and 1.5 g (1.9 mmol) of [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (Pd(dppf)Cl2) was added. The mixture was heated at 100°C for approximately 3 hours. After returning to room temperature, the organic and aqueous layers were separated and extracted with ethyl acetate. Magnesium sulfate was added to this extract to remove water and concentrate it. The toluene solution of the obtained mixture was purified by silica gel column chromatography, and the resulting solution was concentrated to obtain a concentrated toluene solution. Ethanol was added to this toluene solution, and it was concentrated under reduced pressure to obtain an ethanol suspension. The precipitate was filtered at approximately 20°C, and the obtained solid was dried under reduced pressure at approximately 80°C to obtain 13.6 g of the target white solid in a yield of 81%. The synthesis scheme for Step 2 is shown in the following equation.

[0581] [ka]

[0582] <Step 3: Synthesis of 3-bromo-3'',5,5',5''-tetra-tert-butyl-1,1':3',1''-terphenyl> 5.0 g (11.1 mmol) of 2-(3',5,5'-tri-tert-butyl[1,1'-biphenyl]-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 4.8 g (16.7 mmol) of 1,3-dibromo-5-tert-butylbenzene, 4.6 g (33.3 mmol) of potassium carbonate, 56 mL of toluene, 22 mL of ethanol, and 17 mL of tap water were placed in a three-necked flask. After degassing under reduced pressure, the flask was purged with nitrogen, and 50 mg (0.22 mmol) of palladium acetate and 116 mg (0.44 mmol) of triphenylphosphine were added. The mixture was heated at 80°C for approximately 10 hours. After returning to room temperature, the organic and aqueous layers were separated. Magnesium sulfate was added to the solution to remove water and concentrate it. The resulting hexane solution was purified by silica gel column chromatography to obtain 3.0 g of the target product as a white solid in 51.0% yield. Furthermore, the synthesis scheme for 3-bromo-3'',5,5',5''-tetra-tert-butyl-1,1':3',1''-terphenyl in Step 3 is shown in the following formula.

[0583] [ka]

[0584] <Step 4: Synthesis of mmtBumTPoFBi-02> In a three-necked flask, 5.8 g (10.9 mmol) of 3-bromo-3'', 5,5',5''-tetra-tert-butyl-1,1':3',1''-terphenyl obtained in step 3, 3.9 g (10.9 mmol) of N-(1,1'-biphenyl-4-yl)-N-phenyl-9,9-dimethyl-9H-fluoren-2-amine, 3.1 g (32.7 mmol) of sodium tert butoxide, and 55 mL of toluene were placed. After degassing under reduced pressure, the flask was purged with nitrogen, and 64 mg (0.11 mmol) of bis(dibenzylideneacetone)palladium(O) (abbreviation: Pd(dba)2) and 132 mg (0.65 mmol) of tri-tert-butylphosphine were added. The mixture was heated at 80°C for approximately 2 hours. Subsequently, the flask temperature was returned to approximately 60°C, approximately 1 mL of water was added, the precipitated solid was filtered off, and washed with toluene. The filtrate was concentrated, and the resulting toluene solution was purified by silica gel column chromatography. The resulting solution was concentrated to obtain a concentrated toluene solution. Ethanol was added to this toluene solution, and it was concentrated under reduced pressure to obtain an ethanol suspension. The precipitate was filtered at approximately 20°C, and the resulting solid was dried under reduced pressure at approximately 80°C to obtain 8.1 g of the target white solid in a yield of 91%. The synthesis scheme of mmtBumTPoFBi-02 is shown in the following formula.

[0585] [ka]

[0586] Furthermore, nuclear magnetic resonance spectroscopy of the white powder obtained above ( 1 The results of the analysis by 1H-NMR are shown below. From this, it was confirmed that mmtBumTPoFBi-02 was successfully synthesized.

[0587] 1H-NMR.δ(CDCl3):7.56(d,1H,J=7.4Hz),7.50(dd,1H,J=1.7Hz),7.33-7.46(m,11H),7.27-7.29(m,2H),7.22(dd,1H,J=2.3Hz),7 .15(d,1H,J=6.9Hz),6.98-7.07(m,7H),6.93(s,1H),6.84(d,1H,J=6.3Hz),1.38(s,9H),1.37(s,18H),1.31(s,6H),1.20(s,9H).

[0588] ≪Reference synthesis example 2≫ This synthesis example describes the synthesis method for 2-{(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mmtBumBPTzn), which was used in Example 1. The structure of mmtBumBPTzn is shown below.

[0589] [ka]

[0590] <Step 1: Synthesis of 3-bromo-3',5'-di-tert-butylbiphenyl> 1.0 g (4.3 mmol) of 3,5-di-t-butylphenylboronic acid, 1.5 g (5.2 mmol) of 1-bromo-3-iodobenzene, 4.5 mL of 2 mol / L potassium carbonate aqueous solution, 20 mL of toluene, and 3 mL of ethanol were added to a three-necked flask and the mixture was degassed by stirring under reduced pressure. Then, 52 mg (0.17 mmol) of tris(2-methylphenyl)phosphine (abbreviation: P(o-tolyl)3) and 10 mg (0.043 mmol) of palladium(II) acetate were added, and the mixture was reacted under a nitrogen atmosphere at 80°C for 14 hours. After the reaction was complete, extraction was performed with toluene, and the resulting organic layer was dried over magnesium sulfate. This mixture was filtered naturally, and the resulting filtrate was purified by silica gel column chromatography (eluent: hexane) to obtain 1.0 g of the target white solid (yield: 68%). The synthesis scheme for Step 1 is shown below.

[0591] [ka]

[0592] <Step 2: Synthesis of 2-(3',5'-di-tert-butylbiphenyl-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane> 1.0 g (2.9 mmol) of 3-bromo-3',5'-di-tert-butylbiphenyl, 0.96 g (3.8 mmol) of bis(pinacolate)diborone, 0.94 g (9.6 mmol) of potassium acetate, and 30 mL of 1,4-dioxane were added to a three-necked flask and the mixture was degassed by stirring under reduced pressure. Then, 0.12 g (0.30 mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl and 0.12 g (0.15 mmol) of [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride dichloromethane adduct (abbreviation: Pd(dppf)2Cl2·CH2Cl2) were added, and the mixture was reacted under a nitrogen atmosphere at 110°C for 24 hours. After the reaction was complete, extraction with toluene was performed, and the resulting organic layer was dried over magnesium sulfate. The mixture was then filtered by gravity. The resulting filtrate was purified by silica gel column chromatography (eluent: toluene) to obtain 0.89 g of the target yellow oil (yield: 78%). The synthesis scheme for Step 2 is shown below.

[0593] [ka]

[0594] <Step 3: Synthesis of mmtBumBPTzn> In a three-necked flask, 1.5 g (5.6 mmol) of 4,6-diphenyl-2-chloro-1,3,5-triazine, 2.4 g (6.2 mmol) of 2-(3',5'-di-tert-butylbiphenyl-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 2.4 g (11 mmol) of tripotassium phosphate, 10 mL of water, 28 mL of toluene, and 10 mL of 1,4-dioxane were added, and the mixture was degassed by stirring under reduced pressure. Then, 13 mg (0.056 mmol) of palladium(II) acetate and 34 mg (0.11 mmol) of tris(2-methylphenyl)phosphine were added, and the mixture was heated under reflux under a nitrogen atmosphere for 14 hours to allow the reaction to proceed. After the reaction was complete, extraction was performed with ethyl acetate, and the water in the resulting organic layer was removed with magnesium sulfate. The mixture was filtered naturally, and the resulting filtrate was purified by silica gel column chromatography (with the developing solvent chloroform:hexane = changed from 1:5 to 1:3). Recrystallization with hexane yielded 2.0 g of the desired white solid (yield: 51%). The synthesis scheme for Step 3 is shown in the following formula.

[0595] [ka]

[0596] 2.0 g of the obtained white solid was purified by sublimation using the train sublimation method under argon gas flow, pressure of 3.4 Pa, and temperature of 220°C. The solid was then heated. After sublimation purification, 1.8 g of the target white solid was obtained with a recovery rate of 80%.

[0597] Furthermore, nuclear magnetic resonance spectroscopy of the white solid obtained in step 3 above ( 1 The results of the analysis by 1H-NMR are shown below. From these results, it was found that mmtBumBPTzn was obtained in this synthesis example.

[0598] 1 H NMR (CDCl3, 300MHz): δ = 1.44 (s, 18H), 7.51-7.68 (m, 10H), 7.83 (d, 1H), 8.73-8.81 (m, 5H), 9.01 (s, 1H).

[0599] ≪Reference synthesis example 3≫ This example describes the synthesis method of 6-methyl-8-quinolinolatolithium (abbreviated as Li-6mq) used in Example 1. The structural formula of Li-6mq is shown below.

[0600] [ka]

[0601] 2.0 g (12.6 mmol) of 8-hydroxy-6-methylquinoline and 130 mL of anhydrous tetrahydrofuran (THF) were placed in a three-necked flask and stirred. To this solution, 10.1 mL (10.1 mmol) of lithium tert-butoxide (tBuOLi) in 1 M THF solution was added and the mixture was stirred at room temperature for 47 hours. The reaction solution was concentrated to obtain a yellow solid. Acetonitrile was added to this solid, and it was sonicated and filtered to obtain a pale yellow solid. This washing procedure was repeated twice. 1.6 g (95% yield) of a pale yellow solid of Li-6mq was obtained as the filtration product. The synthesis scheme is shown below.

[0602] [ka]

[0603] Next, the absorption and emission spectra of Li-6mq in an anhydrous acetone solution were measured. The absorption spectrum was measured using a UV-Vis spectrophotometer (JASCO Corporation, Model V550), and the spectrum measured with only anhydrous acetone in a quartz cell was subtracted. The emission spectrum was measured using a fluorometer (JASCO Corporation, Model FP-8600).

[0604] As a result, the dehydrated acetone solution of Li-6mq showed an absorption peak at 390nm, and the emission wavelength peak was 540nm (excitation wavelength 385nm).

[0605] ≪Reference synthesis example 4≫ This example describes the synthesis method of N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-N-(1,1'-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as mmtBumTPoFBi-04). The structure of mmtBumTPoFBi-04 is shown below.

[0606] [ka]

[0607] <Step 1: Synthesis of 4-bromo-3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl> 9.0 g (20.1 mmol) of 2-(3',5,5'-tri-tert-butyl[1,1'-biphenyl]-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 6.8 g (24.1 mmol) of 1-bromo-4-iodobenzene, 8.3 g (60.3 mmol) of potassium carbonate, 100 mL of toluene, 40 mL of ethanol, and 30 mL of tap water were placed in a three-necked flask. After degassing under reduced pressure, the flask was purged with nitrogen, and 91 mg (0.40 mmol) of palladium acetate and 211 mg (0.80 mmol) of triphenylphosphine were added. This mixture was heated at 80°C for approximately 4 hours. After returning to room temperature, the organic layer and aqueous layer were separated. Magnesium sulfate was added to this solution, the water was dried, and the solution was concentrated. The resulting hexane solution was purified by silica gel column chromatography to obtain 6.0 g of the target white solid in a yield of 62.5%. The synthesis scheme for Step 1 is shown in the following equation.

[0608] [ka]

[0609] <Step 2: Synthesis of mmtBumTPoFBi-04> 3.0 g (6.3 mmol) of 4-bromo-3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl, 2.3 g (6.3 mmol) of N-(1,1'-biphenyl-4-yl)-N-phenyl-9,9-dimethyl-9H-fluoren-2-amine, 1.8 g (18.9 mmol) of sodium-tert-butoxide, and 32 mL of toluene were placed in a three-necked flask. After degassing under reduced pressure, the flask was purged with nitrogen, and 72 mg (0.13 mmol) of bis(dibenzylideneacetone)palladium(0) and 76 mg (0.38 mmol) of tri-tert-butylphosphine were added. The mixture was heated at 120°C for approximately 8 hours. After that, the temperature of the mixture was lowered to approximately 60°C, approximately 1 mL of water was added, and the precipitated solid was filtered off and washed with toluene. The filtrate was concentrated, and the resulting toluene solution was purified by silica gel column chromatography. The obtained solution was concentrated to obtain a concentrated toluene solution. Ethanol was added to this toluene solution, and it was concentrated under reduced pressure to obtain an ethanol suspension. The precipitate was filtered at approximately 20°C, and the resulting solid was dried under reduced pressure at approximately 80°C to obtain 3.6 g of the target white solid in a yield of 75%. The synthesis scheme for step 2 is shown in the following equation.

[0610] [ka]

[0611] Furthermore, nuclear magnetic resonance spectroscopy of the white solid obtained in step 2 above ( 1 The results of the analysis by 1H-NMR are shown below. This confirms that mmtBumTPoFBi-04 was successfully synthesized in this synthesis example.

[0612] 1H-NMR.δ(CDCl3):7.54-7.56(m,1H),7.53(dd,1H,J=1.7Hz),7.50(dd,1H,J=1.7Hz),7.27-7.47(m,13H),7.23(dd,1H,J=6.3Hz,1.2Hz) ,7.18-7.19(m,2H),7.08-7.00(m,5H),6.88(d,1H,J=1.7Hz),6.77(dd,1H,J=8.0Hz,2.3Hz),1.42(s,9H),1.39(s,18H),(1.29(s,6H).

[0613] ≪Reference synthesis example 5≫ This synthetic example describes the method for synthesizing N-(3',5'-di-tert-butyl-1,1'-biphenyl-4-yl)-bis(9,9-dimethyl-9H-fluorene)-2,2'-amine (abbreviated as mmtBuBiFF). The structure of mmtBuBiFF is shown below.

[0614] [ka]

[0615] <Step 1: Synthesis of 3',5'-di-tert-butyl-4-chloro-1,1'-biphenyl> 30.0 g (114 mmol) of 3,5-di-tert-butyl-1-bromobenzene, 19.2 g (123 mmol) of 4-chlorophenylboronic acid, 46.1 g (334 mmol) of potassium carbonate, 550 mL of toluene, 140 mL of ethanol, and 160 mL of water were placed in a three-necked flask. After degassing under reduced pressure, the flask was purged with nitrogen. 251 mg (1.12 mmol) of palladium acetate and 695 mg (2.28 mmol) of tris(2-methylphenyl)phosphine were added to this mixture, and the mixture was heated under reflux at 90°C for approximately 5 hours. After returning to room temperature, the organic and aqueous layers were separated. Magnesium sulfate was added to the organic layer to dry the water, and the filtered solution was concentrated to obtain a brown, concentrated solution. The obtained solution was purified by silica gel column chromatography. The resulting solution was concentrated and allowed to dry. Hexane was then added and recrystallized. The mixed solution, which contained a precipitated white solid, was cooled on ice and then filtered. The obtained solid was vacuum-dried at approximately 100°C to obtain 29.6 g of the target white solid in a yield of 88%. The synthesis scheme for Step 1 is shown in the following equation.

[0616] [ka]

[0617] <Step 2: Combining mmtBuBiFF> 30.4 g (75.7 mmol) of bis(9,9-dimethyl-9H-fluoren-2-yl)amine, 22.8 g (75.8 mmol) of 3',5'-di-tert-butyl-4-chloro-1,1'-biphenyl, 21.9 g (228 mmol) of sodium-tert-butoxide, and 380 mL of xylene were placed in a three-necked flask. After degassing under reduced pressure, the flask was purged with nitrogen. This mixture was heated and stirred to approximately 60°C. Then, 283 mg (0.773 mmol) of allyl palladium chloride dimer(II) (abbreviation: (AllylPdCl)2) and 1.05 g (2.98 mmol) of di-tert-butyl(1-methyl-2,2-diphenylcyclopropyl)phosphine (abbreviation: cBRIDP®) were added, and this mixture was heated at 100°C for approximately 5 hours. Subsequently, the temperature of the mixture was returned to approximately 60°C, and approximately 2 mL of water was added to precipitate the solid. The precipitated solid was filtered off to obtain a solution. The filtrate was concentrated, and the resulting solution was purified by silica gel column chromatography. The obtained solution was concentrated to obtain a concentrated toluene solution. This toluene solution was added dropwise to ethanol and reprecipitation occurred. The precipitate was filtered at approximately 10°C, and the resulting solid was dried under reduced pressure at approximately 100°C to obtain 44.2 g of the target white solid in 88% yield. The synthesis scheme for Step 2 is shown below.

[0618] [ka]

[0619] Nuclear magnetic resonance spectroscopy of the white solid obtained in step 2 above ( 1 The results of the analysis by 1H-NMR are shown below. From these results, it was found that N-(3',5'-di-tert-butyl-1,1'-biphenyl-4-yl)-bis(9,9-dimethyl-9H-fluorene)-2,2'-amine (abbreviation: mmtBuBiFF) was synthesized in this synthesis example.

[0620] 1H-NMR(500MHz DMSO-d6): δ=7.75(t,4H,J=7.8Hz),7.62(d,2H,J=9.0Hz),7.51(d,2H,J=5.0Hz),7.42(s,2H),7.38(s,1H), 7.34-7.25(m,6H),7.18(d,2H,J=8.0Hz,2.0Hz),7.03(dd,2H,J=8.0Hz,2.0Hz),1.37(s,12H),1.34(s,18H). [Explanation of Symbols]

[0621] 100 circuit boards 101 First electrode 101C electrode 101B First electrode 101G First electrode 101R First electrode 102 Second electrode 103 EL layer 110R Light-emitting device 110G Light-emitting Device 110B Light-emitting device 111 Hole injection layer ...

Claims

1. a first electrode, a second electrode, and at least a light-emitting layer, a first layer, a second layer, and a third layer between the first electrode and the second electrode; the first layer is located between the first electrode and the light emitting layer, the third layer is located between the first layer and the light-emitting layer, the second layer is located between the first layer and the third layer, the first layer comprises a first organic compound; the second layer comprises a second organic compound; the third layer comprises a third organic compound; A light-emitting device, wherein the ordinary refractive index of the second organic compound at any wavelength of 450 nm or more and 650 nm or less is higher than the ordinary refractive index of the first organic compound at the same wavelength and the ordinary refractive index of the third organic compound at the same wavelength.

2. a first electrode, a second electrode, and at least a light-emitting layer, a first layer, a second layer, and a third layer between the first electrode and the second electrode; the first layer is located between the first electrode and the light emitting layer, the third layer is located between the first layer and the light-emitting layer, the second layer is located between the first layer and the third layer, the first layer comprises a first organic compound; the second layer comprises a second organic compound; the third layer comprises a third organic compound; A light-emitting device, wherein the ordinary refractive index of the second organic compound at any wavelength of 455 nm or more and 465 nm or less is higher than the ordinary refractive index of the first organic compound at the same wavelength and the ordinary refractive index of the third organic compound at the same wavelength.

3. a first electrode, a second electrode, and at least a light-emitting layer, a first layer, a second layer, and a third layer between the first electrode and the second electrode; the first layer is located between the first electrode and the light emitting layer, the third layer is located between the first layer and the light-emitting layer, the second layer is located between the first layer and the third layer, the first layer comprises a first organic compound; the second layer comprises a second organic compound; the third layer comprises a third organic compound; A light-emitting device, wherein the ordinary refractive index of the second organic compound at a wavelength of 633 nm is higher than the ordinary refractive index of the first organic compound at a wavelength of 633 nm and the ordinary refractive index of the third organic compound at a wavelength of 633 nm.

4. a first electrode, a second electrode, and at least a light-emitting layer, a first layer, a second layer, and a third layer between the first electrode and the second electrode; the first layer is located between the first electrode and the light emitting layer, the third layer is located between the first layer and the light-emitting layer, the second layer is located between the first layer and the third layer, the light-emitting layer contains a light-emitting material that emits light having a peak wavelength of λ nm, the first layer comprises a first organic compound; the second layer comprises a second organic compound; the third layer comprises a third organic compound; A light-emitting device, wherein the ordinary refractive index of the second organic compound at the wavelength λ nm is higher than the ordinary refractive index of the first organic compound at the wavelength λ nm and the ordinary refractive index of the third organic compound at the wavelength λ nm.

5. In claim 4, A light-emitting device in which the difference between the ordinary refractive index of the second organic compound at the wavelength λ nm and the ordinary refractive index of the first organic compound at the wavelength λ nm, and the difference between the ordinary refractive index of the second organic compound at the wavelength λ nm and the ordinary refractive index of the third organic compound at the wavelength λ nm are each 0.2 or more and less than 0.

5.

6. In claim 5, A light-emitting device, wherein the difference in ordinary refractive index between the first organic compound and the third organic compound at the wavelength λ nm is 0.1 or less.

7. In claim 5 or 6, the product of the film thickness of the second layer and the ordinary refractive index of the second organic compound at the wavelength λ nm is The light emitting device has a wavelength of 70% or more and 130% or less of ¼ of the wavelength λ nm.

8. In any one of claims 1 to 7, A light-emitting device, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the third organic compound is 0.2 eV or less.

9. In any one of claims 1 to 8, A light-emitting device, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.2 eV or less.

10. In any one of claims 1 to 9, The light emitting device, wherein the third layer is fluorine-free.

11. In any one of claims 1 to 10, A light-emitting device, wherein the first layer, the second layer, and the third layer each have a thickness of 25 nm or more and 70 nm or less.

12. In any one of claims 1 to 11, A light-emitting device, wherein the second layer is thicker than the first layer and the third layer.

13. In any one of claims 1 to 12, A light emitting device in which the first layer and the second layer are in contact, and the second layer and the third layer are in contact.

14. In any one of claims 1 to 13, The light emitting device, wherein the first electrode comprises a reflective electrode.

15. In any one of claims 1 to 14, A light-emitting device, wherein the GSP (mV / nm) of the second layer minus the GSP (mV / nm) of the third layer is 10 (mV / nm) or less.

16. In any one of claims 1 to 15, A light-emitting device, wherein the GSP (mV / nm) of the first layer minus the GSP (mV / nm) of the third layer is 10 (mV / nm) or less.

17. In any one of claims 1 to 16, A light emitting device, wherein the GSP (mV / nm) of the third layer is greater than the GSP (mV / nm) of the second layer.

18. In any one of claims 1 to 17, A light emitting device, wherein the GSP (mV / nm) of the third layer is greater than the GSP (mV / nm) of the first layer.

19. In any one of claims 1 to 18, A light emitting device, wherein the GSP (mV / nm) of the second layer is greater than the GSP (mV / nm) of the first layer.

20. a first light emitting device and a second light emitting device; The first light emitting device has the configuration according to any one of claims 1 to 19, the second light-emitting device has at least a light-emitting layer, a fourth layer, a fifth layer, and a sixth layer between a third electrode and the second electrode; the fourth layer, the fifth layer, and the sixth layer have the same configuration as the first layer, the second layer, and the third layer, respectively; A display device in which the difference between the peak wavelength of light emitted by the light emitting material contained in the light emitting layer of the first light emitting device and the peak wavelength of light emitted by the light emitting material contained in the light emitting layer of the second light emitting device is 30 nm or more.

21. a first light emitting device and a second light emitting device; The first light emitting device has the configuration according to any one of claims 1 to 19, the second light-emitting device has at least a light-emitting layer, a fourth layer, a fifth layer, and a sixth layer between a third electrode and the second electrode; the fourth layer, the fifth layer, and the sixth layer have the same thickness as the first layer, the second layer, and the third layer, respectively; A display device in which the difference between the peak wavelength of light emitted by the light emitting material contained in the light emitting layer of the first light emitting device and the peak wavelength of light emitted by the light emitting material contained in the light emitting layer of the second light emitting device is 30 nm or more.

22. A display device comprising: the light-emitting device according to claim 1 ; a sensor; an operation button; and a speaker or a microphone.

23. 23. An electronic device comprising: the display device according to claim 22; a sensor; an operation button; and a speaker or a microphone.

24. A light emitting apparatus comprising the light emitting device according to any one of claims 1 to 21 and a transistor or a substrate.

25. A lighting device comprising: a light-emitting device according to any one of claims 1 to 21; and a housing.

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