Light emitting device

Abstract

A light-emitting device with favorable characteristics is provided.SOLUTION: The light-emitting device includes at least a light-emitting layer and a hole-transport layer between a pair of electrodes, the hole-transport layer is provided in contact with the light-emitting layer, the light-emitting layer includes a first compound that is a host material and a second compound that is a guest material, the hole-transport layer includes a third compound, the HOMO level of the second compound is higher than the HOMO level of the first compound, and the first compound and the third compound each include deuterium.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Organic EL devices (organic EL elements), which utilize electroluminescence (organic electroluminescence) using organic compounds, are being put into practical use as light-emitting devices, light-receiving devices, and light-receiving / light-emitting devices.

[0003] For example, the basic structure of a light-emitting device is a pair of electrodes sandwiching an organic compound layer (EL layer) containing a light-emitting material. By applying a voltage to this device, carriers are injected, and the recombination energy of the carriers is utilized to emit light from the light-emitting material.

[0004] The basic structure of a light-receiving device is a pair of electrodes sandwiching an organic compound layer (active layer) containing a photoelectric conversion material. This device absorbs light energy and generates carriers, which can then obtain electrons from the photoelectric conversion material.

[0005] For example, a functional panel is known in which pixels provided in a display area include a light-emitting element (light-emitting device) and a photoelectric conversion element (light-receiving device) (Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2020 / 152556 [Patent Document 2] Patent Publication No. 2017-139457 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of one embodiment of the present invention is to provide a novel light-emitting device, and an object of another embodiment of the present invention is to provide a light-emitting device with high emission efficiency and high reliability.

[0008] An object of one embodiment of the present invention is to provide a light-emitting device with a long operating lifetime, to reduce manufacturing costs of the light-emitting device, and to provide a light-emitting device, electronic device, or lighting device with low power consumption.

[0009] Note that the description of these problems does not preclude the existence of other problems. Furthermore, one embodiment of the present invention does not necessarily solve all of these problems. Problems other than these will become apparent from the description in the specification, drawings, claims, etc., and other problems can be extracted from the description in the specification, drawings, claims, etc. [Means for solving the problem]

[0010] One embodiment of the present invention is a light-emitting device including at least a light-emitting layer and a hole-transport layer between a pair of electrodes. The light-emitting layer includes a first compound as a host material and a second compound as a guest material. The hole-transport layer includes a third compound, and the HOMO level of the second compound is higher than that of the first compound. The first compound and the third compound are compounds containing deuterium.

[0011] One embodiment of the present invention is a light-emitting device including at least a light-emitting layer and a hole-transport layer between a pair of electrodes. The hole-transport layer is provided in contact with the light-emitting layer. The light-emitting layer includes a first compound as a host material and a second compound as a guest material. The hole-transport layer includes a third compound, the HOMO level of the second compound is higher than that of the first compound, and the first compound and the third compound are compounds containing deuterium.

[0012] One embodiment of the present invention is a light-emitting device including at least a light-emitting layer and a hole-transport layer between a pair of electrodes, the hole-transport layer being in contact with the light-emitting layer, the light-emitting layer including a first compound as a host material and a second compound as a guest material, the hole-transport layer including a third compound, the HOMO level of the second compound being higher than the HOMO level of the first compound, a difference between the HOMO levels of the first compound and the second compound being greater than 0.30 eV and less than 0.90 eV, and the first compound and the third compound being compounds containing deuterium.

[0013] One embodiment of the present invention includes at least a light-emitting layer and a hole-transport layer between a pair of electrodes, the hole-transport layer being in contact with the light-emitting layer, the light-emitting layer including a first compound as a host material and a second compound as a guest material, the hole-transport layer including a third compound, and the first compound having an electron mobility of 1×10 when the square root of an electric field strength [V / cm] is 600. -7 cm 2 / Vs or more, and the first compound and the third compound are compounds having deuterium.

[0014] One embodiment of the present invention is a light-emitting device including at least a light-emitting layer, a hole-transport layer, a first electron-transport layer, and a second electron-transport layer between a pair of electrodes, the hole-transport layer being in contact with the light-emitting layer, the light-emitting layer including a first compound as a host material and a second compound as a guest material, the hole-transport layer including a third compound, the first electron-transport layer being located between the light-emitting layer and the second electron-transport layer, the first electron-transport layer including a compound having a diazine skeleton or a triazine skeleton, the second electron-transport layer including a compound having a phenanthroline skeleton, and the first compound and the third compound being compounds having deuterium.

[0015] In the above invention, the first compound is a light-emitting device that is a compound consisting of only carbon and hydrogen.

[0016] In the above invention, the first compound is a light-emitting device that has an anthracene skeleton.

[0017] In the above invention, the first compound is a light-emitting device that is a compound consisting of only carbon and hydrogen and has an anthracene skeleton.

[0018] One embodiment of the present invention is a light-emitting device including at least a light-emitting layer and a hole-transport layer between a pair of electrodes, the hole-transport layer being in contact with the light-emitting layer, the light-emitting layer including a first compound as a host material and a second compound as a guest material, the hole-transport layer including a third compound, the first compound being a compound containing only carbon and hydrogen, and the first compound and the third compound being compounds containing deuterium.

[0019] In the above invention, the first compound is a light-emitting device that has an anthracene skeleton.

[0020] In the above invention, the light-emitting device has a T1 level of the third compound higher than the T1 level of the first compound.

[0021] In the above invention, the third compound is a light-emitting device that is a compound having only one triarylamine skeleton.

[0022] In the above invention, the third compound is a compound different from the compound contained in the light-emitting layer.

[0023] In the above invention, the second compound is a fluorescent compound.

[0024] In the above invention, the light-emitting device further comprises an electron transport layer between the pair of electrodes, the electron transport layer having a laminated structure of two or more layers.

[0025] In the above invention, the light-emitting device further comprises an electron transport layer between the pair of electrodes, the electron transport layer not containing an 8-quinolinol metal complex.

[0026] In the above invention, the second compound is a light-emitting device having four or more fused heteroaromatic rings.

[0027] Another embodiment of the present invention is an electronic device including the light-emitting device or the light-receiving device, and a sensor, an operation button, a speaker, or a microphone.

[0028] Another embodiment of the present invention is a lighting device including the above-described light-emitting device or the above-described light-receiving device and a housing. [Effects of the Invention]

[0029] According to one embodiment of the present invention, a novel light-emitting device can be provided. Furthermore, according to one embodiment of the present invention, a light-emitting device with high emission efficiency and high reliability can be provided.

[0030] According to one embodiment of the present invention, a light-emitting device with a long operating lifetime can be provided. Furthermore, according to one embodiment of the present invention, the manufacturing cost of the light-emitting device can be reduced. Furthermore, according to one embodiment of the present invention, a light-emitting device, an electronic device, or a lighting device with low power consumption can be provided.

[0031] Note that the description of these effects does not preclude the existence of other effects. Furthermore, one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0032] [Figure 1] 1(A) and 1(B) are schematic diagrams of a light-emitting device. [Figure 2] 2A to 2E are diagrams illustrating the configuration of a light-emitting device. [Figure 3] 3A and 3B are a top view and a cross-sectional view of the light-emitting device. [Figure 4] 4A to 4G are top views showing examples of pixel configurations. [Figure 5] 5A to 5I are top views showing examples of pixel configurations. [Figure 6] 6(A) and 6(B) are perspective views showing configuration examples of a display module. [Figure 7] 7(A) and 7(B) are cross-sectional views showing examples of the configuration of a display device. [Figure 8] FIG. 8 is a perspective view showing an example of the configuration of a display device. [Figure 9] FIG. 9 is a cross-sectional view showing an example of the configuration of a display device. [Figure 10] FIG. 10 is a cross-sectional view showing an example of the configuration of a display device. [Figure 11] 11A to 11C are cross-sectional views and top views showing a structural example of a display device. [Figure 12] FIG. 12 is a cross-sectional view showing an example of the configuration of a display device. [Figure 13] 13A to 13C are cross-sectional views and top views showing a structural example of a display device. [Figure 14] 14A to 14D are diagrams showing examples of electronic devices. [Figure 15] 15A to 15F are diagrams showing examples of electronic devices. [Figure 16] 16A to 16G are diagrams showing examples of electronic devices. [Figure 17] FIG. 17 is a diagram illustrating the configuration of a light-emitting device. [Figure 18] FIG. 18 is a diagram illustrating the luminance-current density characteristics of a light-emitting device. [Figure 19] FIG. 19 is a diagram illustrating the luminance-voltage characteristics of a light-emitting device. [Figure 20] FIG. 20 is a graph illustrating the current efficiency-luminance characteristics of a light-emitting device. [Figure 21] FIG. 21 is a diagram illustrating the current density-voltage characteristics of a light-emitting device. [Figure 22] FIG. 22 is a diagram illustrating the electroluminescence spectrum of the light-emitting device. [Figure 23] FIG. 23 is a diagram illustrating the change in luminance with respect to the driving time of the light-emitting device. [Figure 24] FIG. 24 is a diagram illustrating the luminance-current density characteristics of a light-emitting device. [Figure 25] FIG. 25 is a diagram illustrating the luminance-voltage characteristics of a light-emitting device. [Figure 26] FIG. 26 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting device. [Figure 27] FIG. 27 is a diagram illustrating the current density-voltage characteristics of a light-emitting device. [Figure 28] FIG. 28 is a diagram illustrating the electroluminescence spectrum of the light-emitting device. [Figure 29]FIG. 29 is a diagram illustrating the change in luminance with respect to the driving time of the light-emitting device. [Figure 30] FIG. 30 is a diagram illustrating the luminance-current density characteristics of a light-emitting device. [Figure 31] FIG. 31 is a diagram illustrating the luminance-voltage characteristics of a light-emitting device. [Figure 32] FIG. 32 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting device. [Figure 33] FIG. 33 is a diagram illustrating the current density-voltage characteristics of a light-emitting device. [Figure 34] FIG. 34 is a diagram illustrating the electroluminescence spectrum of the light-emitting device. [Figure 35] FIG. 35 is a diagram illustrating the change in luminance with respect to the driving time of the light-emitting device. [Figure 36] FIG. 36 is a diagram illustrating the luminance-current density characteristics of a light-emitting device. [Figure 37] FIG. 37 is a diagram illustrating the luminance-voltage characteristics of a light-emitting device. [Figure 38] FIG. 38 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting device. [Figure 39] FIG. 39 is a diagram illustrating the current density-voltage characteristics of a light-emitting device. [Figure 40] FIG. 40 is a diagram illustrating the electroluminescence spectrum of the light-emitting device. [Figure 41] FIG. 41 is a diagram illustrating the change in luminance with respect to the driving time of a light-emitting device. [Figure 42] FIG. 42 is a diagram illustrating the luminance-current density characteristics of a light-emitting device. [Figure 43] FIG. 43 is a diagram illustrating the luminance-voltage characteristics of a light-emitting device. [Figure 44] FIG. 44 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting device. [Figure 45] FIG. 45 is a diagram illustrating the current density-voltage characteristics of a light-emitting device. [Figure 46]FIG. 46 is a diagram illustrating the electroluminescence spectrum of the light-emitting device. [Figure 47] FIG. 47 is a diagram illustrating the change in luminance with respect to the driving time of a light-emitting device. [Figure 48] FIG. 48 is a diagram illustrating the luminance-current density characteristics of a light-emitting device. [Figure 49] FIG. 49 is a diagram illustrating the luminance-voltage characteristics of a light-emitting device. [Figure 50] FIG. 50 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting device. [Figure 51] FIG. 51 is a diagram illustrating the current density-voltage characteristics of a light-emitting device. [Figure 52] FIG. 52 is a diagram illustrating the electroluminescence spectrum of the light-emitting device. [Figure 53] FIG. 53 is a diagram illustrating the change in luminance with respect to the driving time of a light-emitting device. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and various changes in form and details are possible without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0034] As used herein, the terms "deuterated organic compound," "deuterated compound," "deuterium compound," or "organic compound containing deuterium" refer to an organic compound in which, when focusing on hydrogen (including deuterium) present at a specific position in the organic compound, the proportion of the hydrogen (including deuterium) that is deuterium is greater than the natural abundance of deuterium. This proportion is preferably sufficiently greater than the natural abundance. In this case, "sufficiently" refers to, for example, 7.5% or more of the hydrogen (including deuterium) being deuterated. The deuteration of an organic compound can be confirmed by methods such as NMR and mass spectrometry.

[0035] For ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings, etc.

[0036] In addition, in this specification and the like, when describing the configuration of the invention using drawings, the same reference numerals are used in common between different drawings.

[0037] (Embodiment 1) In this embodiment, an organic EL device (hereinafter also referred to as a light-emitting device) in which an organic compound having deuterium, which is one embodiment of the present invention, is used in a light-emitting layer and a hole-transport layer will be described.

[0038] <Example of light-emitting device configuration> 1(A) is a schematic cross-sectional view of a light-emitting device 10 of one embodiment of the present invention. The light-emitting device 10 includes a pair of electrodes (a first electrode 101 and a second electrode 102) and an organic compound layer 103 provided between the pair of electrodes. The organic compound layer 103 includes at least a light-emitting layer 113. In addition, in this embodiment 1, the organic compound layer 103 includes a hole-transport layer 112.

[0039] The organic compound layer 103 shown in FIG. 1A includes functional layers such as a hole-injection layer 111, a hole-transport layer 112, an electron-transport layer 114, and an electron-injection layer 115 in addition to the light-emitting layer 113.

[0040] In the present embodiment, the first electrode 101 of the pair of electrodes is described as an anode and the second electrode 102 as a cathode, but the configuration of the light-emitting device 10 is not limited to this. That is, the first electrode 101 may be the cathode and the second electrode 102 may be the anode, and the layers between the electrodes may be stacked in the reverse order. That is, the stacking order may be, from the anode side, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, the electron transport layer 114, and the electron injection layer 115.

[0041] 1A, the organic compound layer 103 may have at least one selected from a hole-injection layer 111, a hole-transport layer 112, an electron-transport layer 114, and an electron-injection layer 115. Alternatively, the organic compound layer 103 may have a functional layer having a function of reducing a hole- or electron-injection barrier, improving hole- or electron-transport properties, inhibiting hole- or electron-transport properties, or suppressing quenching caused by an electrode. Each functional layer may be a single layer or may have a stacked structure of multiple layers.

[0042] Fig. 1(B) is a cross-sectional view showing an example of the light-emitting layer 113 shown in Fig. 1(A). The light-emitting layer 113 shown in Fig. 1(B) includes a host material 118 (organic compounds 118_1 and 118_2) and a guest material 119 (light-emitting substance). Note that the organic compound 118_1 and the organic compound 118_2 may be the same compound. In that case, the host material 118 used in the light-emitting layer is one type of material.

[0043] The guest material 119 may be a light-emitting organic compound. As the light-emitting organic compound, either a substance that emits fluorescence (hereinafter also referred to as a fluorescent compound) or a substance that emits phosphorescence (hereinafter also referred to as a phosphorescent compound) can be suitably used. In particular, a fluorescent compound is preferred as the light-emitting material for a blue device because the reliability of the light-emitting device is excellent. A phosphorescent compound is preferred as the light-emitting material for a green device and a red device from the viewpoints of luminous efficiency and power consumption.

[0044] When a phosphorescent compound is used as the guest material in the light-emitting layer 113, the host material 118 is present in the largest amount by weight, and the guest material 119 is dispersed in the host material 118. In this case, the lowest triplet excitation level (T1 level) of the host material 118 (organic compounds 118_1 and 118_2) of the light-emitting layer 113 is preferably higher than the T1 level of the guest material 119 of the light-emitting layer 113.

[0045] When a phosphorescent compound is used as a guest material, the host material 118 (organic compound 118_1 and organic compound 118_2) in the light-emitting layer 113 preferably forms an exciplex (also referred to as an exciplex). An exciplex is an excited state consisting of two or more substances, and in the case of photoexcitation, it is formed when one substance in an excited state interacts with the other substance in a ground state.

[0046] Furthermore, when a fluorescent compound is used as the guest material in the light-emitting layer 113, the host material 118 is present in a larger amount by weight than the guest material, and the guest material 119 is dispersed in the host material 118. As described above, it is preferable that the lowest triplet excitation level (T1 level) of the host material 118 (organic compounds 118_1 and 118_2) of the light-emitting layer 113 is lower than the T1 level of the guest material 119 of the light-emitting layer 113, because this increases the proportion of delayed fluorescent components due to triplet-triplet annihilation (TTA), thereby achieving the effect of increasing luminous efficiency.

[0047] In a light-emitting device using a fluorescent light-emitting layer, the host material 118 of the light-emitting layer may be one type. In this case, the organic compound 118_1 and the organic compound 118_2 are the same material. In a light-emitting device using a fluorescent light-emitting layer, two types of host material 118 of the light-emitting layer may be used. Furthermore, the light-emitting layer may have a laminated structure in which the same or different fluorescent compounds are dispersed in two different host materials. When the light-emitting layer has a laminated structure, each layer may use one or two types of host material.

[0048] Depending on the configuration of the light-emitting layer 113 or the electron transport layer 114 as described above, the light-emitting device may have an excess of electrons. An excess of electrons is a situation in which the carrier recombination region in the light-emitting layer 113 is biased toward the hole transport layer 112 and becomes narrower. This situation is advantageous from the perspective of optical interference, and therefore can increase the light-emitting efficiency. On the other hand, an increase in the exciton density in the light-emitting layer 113 or an increase in the ease with which electrons reach the hole transport layer 112 tends to accelerate degradation of the light-emitting device.

[0049] The present inventors have found that in a light-emitting device under such specific conditions where excess electrons occur, by using a deuterated compound in the hole transport layer 112, a highly reliable light-emitting device can be obtained in which degradation is suppressed while achieving high luminous efficiency, as will be described in detail below.

[0050] First, in the light-emitting layer 113, if the highest occupied molecular orbital (HOMO) level of the guest material 119 is higher than the HOMO level of the host material 118, holes are trapped in the guest material 119. In such a light-emitting layer 113, injected holes are trapped on the anode side of the light-emitting layer and are difficult to move, while electrons flow from the cathode side, which makes it easy for the above-mentioned electron excess to occur.

[0051] Therefore, one embodiment of the present invention is a structure in which, when the HOMO level of the guest material 119 is higher than that of the host material 118, a deuterated compound is used for the host material 118 of the light-emitting layer 113 and for layers provided in the vicinity of the light-emitting layer 113, such as the hole-transport layer 112. A deuterated compound has increased stability in an excited state or in a state in which carriers are retained; therefore, by using a deuterated compound for the host material 118 and the hole-transport layer 112 in an electron-rich device, the reliability of the light-emitting device can be improved.

[0052] In particular, in a configuration of the light-emitting layer 113 in which the HOMO level of the guest material 119 is higher than that of the host material 118, if the difference between the HOMO levels of the guest material 119 and the host material 118 is greater than 0.30 eV, particularly 0.35 eV or greater, or 0.40 eV or greater, high luminous efficiency can be expected in the light-emitting layer 113, but hole trapping properties will be significantly increased. As a result, electrons will be supplied in excess, which may further deteriorate not only the compound used in the light-emitting layer 113 but also the compounds used in layers adjacent to the light-emitting layer 113, such as the hole-transport layer 112. In this case, using deuterated compounds for the host material 118 of the light-emitting layer 113 and the hole-transport layer 112 can provide a highly reliable light-emitting device.

[0053] On the other hand, if the hole-trapping property is too strong, the number of electrons reaching the hole-transport layer 112 increases, which may reduce the exciton generation rate in the light-emitting layer and impair the luminous efficiency. Therefore, the difference between the HOMO level of the guest material 119 and the HOMO level of the host material 118 is preferably less than 0.90 eV, more preferably 0.70 eV or less, and even more preferably 0.50 eV or less. With this configuration, a light-emitting device with high luminous efficiency and high reliability can be provided.

[0054] The lowest unoccupied molecular orbital (LUMO) level and HOMO level of a material can be derived from its electrochemical properties (reduction potential and oxidation potential). Electrochemical properties can be measured using techniques such as cyclic voltammetry (CV) or differential pulse voltammetry (DPV). However, when comparing values ​​between different compounds, it is preferable to use values ​​estimated using the same measurement method. The LUMO level or HOMO level can also be derived using photoelectron spectroscopy, optical absorption spectroscopy, or inverse photoelectron spectroscopy. However, because the apparent end of the optical absorption spectrum does not necessarily reflect the HOMO-LUMO gap, it is preferable to use the electrochemical properties described above when estimating the LUMO level or HOMO level.

[0055] Although the above description has been given of the case where the light-emitting layer 113 has hole-trapping properties, there are other configurations in which the light-emitting device is prone to becoming electron-excessive.

[0056] For example, if the electron mobility of the host material 118 in the light-emitting layer 113 is high, the light-emitting device is likely to have an excess of electrons. -7 cm 2 In the case where the host material 118 has a refractive index of 1 / Vs or higher, a light-emitting device using a deuterated compound for the host material 118 of the light-emitting layer 113 and the hole-transport layer 112 according to one embodiment of the present invention is preferable.

[0057] For example, when a compound having four or more fused heteroaromatic rings in its molecular structure is used as the guest material 119, the guest material 119 can easily accept and transport electrons. Therefore, while high light-emitting efficiency can be expected when used in a light-emitting device, the guest material 119 is likely to cause an excess of electrons. That is, electrons can easily reach the hole-transport layer, which may further deteriorate compounds used in the light-emitting layer and layers in contact with the light-emitting layer, such as the hole-transport layer. Therefore, by using a light-emitting device according to one embodiment of the present invention, in which a deuterated compound is used in the host material 118 of the light-emitting layer 113 and in layers in contact with the light-emitting layer, such as the hole-transport layer, deterioration of the hole-transport layer due to electrons can be suppressed. Furthermore, this structure can suppress deterioration over time due to operation of the light-emitting device and achieve high light-emitting efficiency.

[0058] Furthermore, when the electron-transport layer 114 has a stacked structure of two or more layers, the light-emitting device may have an excess of electrons. That is, when the electron-transport layer 114 includes at least a first electron-transport layer and a second electron-transport layer, the first electron-transport layer is provided between the light-emitting layer 113 and the second electron-transport layer. In this case, it is particularly preferable that the first electron-transport layer contains a compound having a diazine or triazine skeleton, and the second electron-transport layer contains a compound having a phenanthroline skeleton, from the viewpoint of providing a device with a low driving voltage. While this structure can provide a device with low power consumption, it also has very high electron-transporting properties, making the light-emitting device prone to an excess of electrons. Therefore, in a light-emitting device having the electron-transport layer 114 with such a structure, using deuterated compounds for the host material 118 of the light-emitting layer 113 and the hole-transport layer 112 is one embodiment of the present invention, and can achieve both low power consumption and high reliability.

[0059] Furthermore, when the difference between the LUMO level of the host material 118 of the light-emitting layer 113 and the LUMO level of the material used in the electron transport layer 114 in contact with the light-emitting layer 113 is small, the electron injection from the electron transport layer 114 to the light-emitting layer 113 becomes high, which is likely to lead to an excess of electrons. In particular, when the difference between the LUMO level of the host material 118 of the light-emitting layer 113 and the LUMO level of the material used in the electron transport layer 114 in contact with the light-emitting layer 113 is 0.25 eV or less, the electron injection becomes very high. Therefore, in a light-emitting device having such a configuration, by using a deuterium compound in the hole transport layer 112, it is possible to obtain high luminous efficiency while suppressing luminance degradation due to operation of the light-emitting device.

[0060] In the first embodiment, when the hole transport layer 112 has a structure in which two or more layers with different compositions are stacked, it is particularly preferable to use a deuterated compound in the layer in contact with the light-emitting layer. This is because, in the hole transport layer 112 of the above-described electron-rich light-emitting device, the layer in the hole transport layer 112 in contact with the light-emitting layer is susceptible to deterioration due to electrons.

[0061] It is preferable that the material used for the hole transport layer 112 is different from the material used for the light-emitting layer 113. If the same material is used for the hole transport layer 112 and the light-emitting layer 113, electrons injected into the light-emitting layer will easily move to the adjacent hole transport layer 112, which may result in a decrease in luminous efficiency or deterioration of the hole transport layer 112. However, by using different materials for the hole transport layer 112 and the light-emitting layer 113, it is possible to prevent holes and electrons from moving to the hole transport layer 112, thereby increasing the luminous efficiency. Furthermore, by using different materials for the hole transport layer 112 and the light-emitting layer 113, it is possible to provide a highly efficient light-emitting device with a good carrier balance.

[0062] Aromatic amine compounds are preferred as deuterated compounds for the hole transport layer 112. Compounds with only one triarylamine skeleton in their molecular structure are particularly preferred. These compounds tend to have a deeper HOMO than compounds such as diamines or triamines, which facilitates hole injection into the light-emitting layer and makes them suitable for electron-rich devices from the standpoint of reliability. Furthermore, compounds such as diamines and triamines tend to require high deposition temperatures, making them susceptible to thermal decomposition during deposition. Decomposition of the compound may reduce the purity of the deposited film and potentially reduce the reliability of the light-emitting device. On the other hand, compounds with only one triarylamine skeleton tend to be deposited at temperatures significantly lower than the decomposition temperature of the compound, allowing for the formation of highly pure deposited films and the provision of highly reliable light-emitting devices.

[0063] Examples of the deuterated compound used in the hole transport layer 112 include, but are not limited to, compounds represented by the following structural formulas (100) to (212).

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] [ka]

[0069]

change

[0070]

change

[0071]

change

[0072]

change

[0073]

change

[0074]

change

[0075]

change

[0076]

change

[0077]

change

[0078]

change

[0079]

change

[0080] In the above-described electron-rich device, the recombination region in the light-emitting layer 113 is narrowed, resulting in a high exciton density. As a result, in a fluorescent device using a fluorescent compound, the above-described TTA is more likely to occur, resulting in high luminous efficiency.

[0081] Therefore, in the above structure, the guest material 119 is preferably a fluorescent compound. Furthermore, when a fluorescent compound is used as the guest material 119, a compound consisting only of carbon and hydrogen is preferable as the host material 118 to enhance reliability. Furthermore, using a compound having an anthracene skeleton as the host material 118 facilitates TTA and improves luminous efficiency. Furthermore, compounds having an anthracene skeleton have high electrochemical stability and can excite blue guest materials, making them suitable as host materials for blue devices. While compounds having an anthracene skeleton are thus suitable as host materials, they have high electron transport properties and are difficult for holes to enter, making them prone to electron excess. Therefore, by using a deuterated compound for the hole-transport layer 112, the problem of deterioration due to electron excess can be suppressed while taking advantage of the advantages of using a compound having an anthracene skeleton as a host material. From these perspectives, light-emitting devices using an anthracene compound consisting only of carbon and hydrogen as the host material 118 are particularly suitable.

[0082] Examples of the deuterated compound used for the host material 118 include, but are not limited to, compounds represented by the following structural formulas (400) to (435).

[0083] [ka]

[0084] [ka]

[0085] [ka]

[0086] When the organic compound layer 103 contains an 8-quinolinol metal complex, if a separate coating method using photolithography is adopted, the organic compound layer 103 may be exposed to an etching solution, which may etch the 8-quinolinol metal complex. Therefore, it is preferable not to use an 8-quinolinol metal complex in the organic compound layer 103. In particular, it is preferable to use a compound that does not contain an 8-quinolinol metal complex in the outermost layer, such as the electron transport layer 114.

[0087] <Basic structure of light-emitting devices> Displays using light-emitting devices as display devices (organic EL displays) have been in practical use for some time. These displays have pixels that emit light of at least three colors, for example, red, green, and blue, to achieve full-color display.

[0088] A light-emitting device is provided for each of the pixels for each emission color, and in a side-by-side type, or so-called color-coded display, each light-emitting device has a different light-emitting material depending on the emission color of the corresponding pixel.

[0089] The basic structure of a light-emitting device will be described in more detail below with reference to Figures 2(A) to 2(E). Figure 2(A) shows a light-emitting device having a structure (single structure) in which an organic compound layer (also called an EL layer) including a light-emitting layer is sandwiched between a pair of electrodes. Specifically, the light-emitting device has a structure in which an organic compound layer 103 is sandwiched between a first electrode 101 and a second electrode 102.

[0090] 2B shows a light-emitting device having a stacked structure (tandem structure) in which a plurality of organic compound layers (103a, 103b) (two layers in FIG. 2B) are disposed between a pair of electrodes and a charge generation layer 106 is disposed between the organic compound layers. A light-emitting device having a tandem structure can realize a highly efficient light-emitting device without changing the amount of current.

[0091] The charge generation layer 106 has a function of injecting electrons into one organic compound layer (103a or 103b) and injecting holes into the other organic compound layer (103b or 103a) when a potential difference is generated between the first electrode 101 and the second electrode 102. Therefore, in FIG. 2B, when a voltage is applied to the first electrode 101 so that the potential thereof is higher than that of the second electrode 102, electrons are injected from the charge generation layer 106 into the organic compound layer 103a and holes are injected into the organic compound layer 103b.

[0092] From the viewpoint of light extraction efficiency, the charge generation layer 106 is preferably transparent to visible light (specifically, the visible light transmittance of the charge generation layer 106 is 40% or more). The charge generation layer 106 functions even if it has lower conductivity than the first electrode 101 and the second electrode 102.

[0093] FIG. 2C shows a stacked structure of the organic compound layer 103 of the light-emitting device according to one embodiment of the present invention. In this case, the first electrode 101 functions as an anode, and the second electrode 102 functions as a cathode. The organic compound layer 103 has a structure in which a hole injection layer 111, a hole transport layer 112, a light-emitting layer 113, an electron transport layer 114, and an electron injection layer 115 are sequentially stacked over the first electrode 101. The light-emitting layer 113 may have a stacked structure of a plurality of light-emitting layers emitting different light colors. For example, a light-emitting layer containing a red light-emitting substance, a light-emitting layer containing a green light-emitting substance, and a light-emitting layer containing a blue light-emitting substance may be stacked, or a layer containing a carrier-transporting material may be interposed between the light-emitting layers. Alternatively, a light-emitting layer containing a yellow light-emitting substance and a light-emitting layer containing a blue light-emitting substance may be combined. However, the stacked structure of the light-emitting layer 113 is not limited to the above. For example, the light-emitting layer 113 may have a structure in which multiple light-emitting layers emitting the same light-emitting color are stacked. For example, a first light-emitting layer containing a blue light-emitting substance and a second light-emitting layer containing a blue light-emitting substance are stacked, or a layer containing a carrier-transporting material is interposed between the layers. A structure in which multiple light-emitting layers emitting the same light-emitting color are stacked may have higher reliability than a single-layer structure. Even in the case of a tandem structure having multiple light-emitting layers as shown in FIG. 2B, the layers of the organic compound layer 103 are stacked in order from the anode side as described above. When the first electrode 101 is a cathode and the second electrode 102 is an anode, the stacking order of the organic compound layer 103 is reversed. Specifically, the structure is such that 111 on the first electrode 101, which is a cathode, is an electron injection layer, 112 is an electron transport layer, 113 is a light-emitting layer, 114 is a hole transport layer, and 115 is a hole injection layer.

[0094] The light-emitting layer 113 included in the organic compound layers (103, 103a, 103b) each contains a light-emitting substance and an appropriate combination of multiple substances, and can be configured to emit fluorescent or phosphorescent light of a desired emission color. The light-emitting layer 113 may also have a stacked structure with different emission colors. In this case, different materials may be used for the light-emitting substance and other substances used in each stacked light-emitting layer. Alternatively, a structure may be used in which different emission colors are emitted from the multiple organic compound layers (103a, 103b) shown in Figure 2(B). In this case, different materials may be used for the light-emitting substance and other substances used in each light-emitting layer.

[0095] In addition, in a light-emitting device according to one embodiment of the present invention, for example, the first electrode 101 shown in FIG. 2C may be a reflective electrode, the second electrode 102 may be a semi-transmissive and semi-reflective electrode, and a micro-optical resonator (microcavity) structure may be formed. This allows light emitted from the light-emitting layer 113 included in the organic compound layer 103 to resonate between the two electrodes, thereby enhancing the intensity of light emitted from the second electrode 102. Therefore, high definition can be easily achieved. Furthermore, the intensity of light emitted from a specific wavelength in the front direction can be enhanced, thereby reducing power consumption.

[0096] When the first electrode 101 of the light-emitting device is a reflective electrode having a laminated structure of a reflective conductive material and a light-transmitting conductive material (transparent conductive film), optical adjustment can be performed by controlling the film thickness of the transparent conductive film. Specifically, it is preferable to adjust the optical distance (product of film thickness and refractive index) between the first electrode 101 and the second electrode 102 to mλ / 2 (where m is an integer of 1 or greater) or in the vicinity thereof, for the wavelength λ of light obtained from the light-emitting layer 113.

[0097] Furthermore, in order to amplify the desired light (wavelength: λ) obtained from the light-emitting layer 113, it is preferable to adjust the optical distance from the first electrode 101 to the region (light-emitting region) in the light-emitting layer 113 where the desired light is obtained and the optical distance from the second electrode 102 to the region (light-emitting region) in the light-emitting layer 113 where the desired light is obtained to be (2m'+1)λ / 4 (where m' is an integer of 1 or greater) or close to that. Note that the light-emitting region here refers to the recombination region of holes and electrons in the light-emitting layer 113.

[0098] By performing such optical adjustment, the spectrum of the specific monochromatic light obtained from the light-emitting layer 113 can be narrowed, and light emission with good color purity can be obtained.

[0099] In the above case, the optical distance between the first electrode 101 and the second electrode 102 can be strictly defined as the total thickness from the reflective region of the first electrode 101 to the reflective region of the second electrode 102. However, since it is difficult to precisely determine the reflective regions of the first electrode 101 and the second electrode 102, the above-mentioned effect can be sufficiently achieved by assuming any position of the first electrode 101 and the second electrode 102 as the reflective region. Furthermore, the optical distance between the first electrode 101 and the light-emitting layer from which desired light is obtained can be strictly defined as the optical distance between the reflective region of the first electrode 101 and the light-emitting region of the light-emitting layer from which desired light is obtained. However, since it is difficult to precisely determine the reflective region of the first electrode 101 and the light-emitting region of the light-emitting layer from which desired light is obtained, the above-mentioned effect can be sufficiently achieved by assuming any position of the first electrode 101 as the reflective region and any position of the light-emitting layer from which desired light is obtained as the light-emitting region.

[0100] The light-emitting device shown in Figure 2(D) has a tandem structure. The tandem structure allows the device to emit light with high brightness. Furthermore, the tandem structure can reduce the current required to obtain the same brightness compared to a single structure, thereby improving reliability. Furthermore, power consumption can be reduced.

[0101] The light-emitting device shown in FIG. 2(E) is an example of the tandem-structure light-emitting device shown in FIG. 2(B). As shown in the figure, the light-emitting device has a structure in which three organic compound layers (103a, 103b, 103c) are stacked with charge generation layers (106a, 106b) sandwiched between them. Each of the three organic compound layers (103a, 103b, 103c) has a light-emitting layer (113a, 113b, 113c), and the light-emitting colors of the light-emitting layers can be freely combined. For example, the light-emitting layer 113a can be blue, the light-emitting layer 113b can be red, green, or yellow, and the light-emitting layer 113c can be blue. Alternatively, the light-emitting layer 113a can be red, the light-emitting layer 113b can be blue, green, or yellow, and the light-emitting layer 113c can be red.

[0102] In the light-emitting device according to one embodiment of the present invention, at least one of the first electrode 101 and the second electrode 102 is a light-transmitting electrode (such as a transparent electrode or a semi-transmitting / semi-reflective electrode). When the light-transmitting electrode is a transparent electrode, the visible light transmittance of the transparent electrode is 40% or more. In addition, when the semi-transmitting / semi-reflective electrode is used, the visible light reflectance of the semi-transmitting / semi-reflective electrode is 20% or more and 80% or less, preferably 40% or more and 70% or less. Furthermore, these electrodes have a resistivity of 1×10 -2 It is preferable to keep it at Ω·cm or less.

[0103] In the above-described light-emitting device according to one embodiment of the present invention, when one of the first electrode 101 and the second electrode 102 is a reflective electrode (a reflective electrode), the reflectivity of the reflective electrode for visible light is set to 40% to 100%, preferably 70% to 100%. -2 It is preferable to keep it at Ω·cm or less.

[0104] <Specific structure of light-emitting device> Next, a specific structure of a light-emitting device according to one embodiment of the present invention will be described. Here, a tandem structure will be described with reference to FIG. 2D. The single-structure light-emitting devices shown in FIGS. 2A and 2C also have the same organic compound layer structure. When the light-emitting device shown in FIG. 2D has a microcavity structure, the first electrode 101 is formed as a reflective electrode, and the second electrode 102 is formed as a semi-transmissive and semi-reflective electrode. Therefore, a single or multiple desired electrode materials can be used to form a single layer or a stacked layer. The second electrode 102 is formed by selecting an appropriate material after the organic compound layer 103b is formed.

[0105] <Light-emitting device materials> <Light-emitting layer> The light-emitting layers (113, 113a, 113b) are layers containing a light-emitting substance. Light-emitting substances that can be used for the light-emitting layers (113, 113a, 113b) include substances that emit light of colors such as blue, purple, blue-purple, green, yellow-green, yellow, orange, and red. When multiple light-emitting layers are provided, different light-emitting substances can be used for each light-emitting layer to produce different light-emitting colors (for example, white light emission obtained by combining complementary light-emitting colors). Furthermore, a stacked structure in which each light-emitting layer contains different light-emitting substances may be used.

[0106] Furthermore, the light-emitting layers (113, 113a, 113b) may contain one or more organic compounds (host materials, etc.) in addition to the light-emitting substance (guest material).

[0107] 1B can be used as the light-emitting layer 113. In the light-emitting layer 113, the host material 118 is present in the largest amount by weight, and the guest material 119 (phosphorescent compound) is dispersed in the host material 118. The T1 level of the host material 118 (organic compounds 118_1 and 118_2) of the light-emitting layer 113 is preferably higher than the T1 level of the guest material of the light-emitting layer 113 (guest material 119).

[0108] The T1 level can be calculated from the emission edge obtained by measuring the emission spectrum (phosphorescence spectrum) at a low temperature (e.g., 10 K) using a thin film of the sample. The sample form when measuring the emission spectrum of the luminescence center substance may be a thin film or a solution, but a solution is preferred from the viewpoint of verifying the state of isolated molecules. A solvent with relatively low polarity, such as toluene or chloroform, is preferred for the solution. When the luminescence center substance is a phosphorescent compound, the T1 level can be measured at a low temperature (e.g., 10 K) or room temperature (e.g., 298 K), and can be calculated from the emission edge obtained by measuring the emission spectrum (phosphorescence spectrum). The emission edge can be calculated by drawing a tangent at the point where the absolute value of the slope on the short-wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is maximized, and then calculating the tangent from the intersection of the tangent with the horizontal axis (wavelength) or the baseline.

[0109] Light-emitting substances that can be used as guest materials include, for example, substances that emit red light. Furthermore, as the substance that emits red light, a substance that emits phosphorescence, particularly an organometallic complex, is more preferable. Examples of such light-emitting substances include organometallic compounds 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(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]). Iridium complexes, organometallic iridium complexes with 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)]), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’) iridium(III) acetylacetonate (abbreviated as [Ir(piq)2(acac)]), (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC]iridium(III), and (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC]iridium(III). In addition to iridium complexes, platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP) and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]) are also useful. These complexes have emission peaks in the wavelength range from 600 nm to 700 nm. Furthermore, organometallic iridium complexes with a pyrazine skeleton can emit red light with good chromaticity. Other known red phosphorescent materials can also be used.

[0110] Furthermore, when a red light-emitting substance is not used as the light-emitting substance, or when light-emitting devices having different configurations are included in the same light-emitting device, the light-emitting substance may be a fluorescent light-emitting substance, a phosphorescent light-emitting substance, a substance exhibiting thermally activated delayed fluorescence (TADF), or any other light-emitting substance.

[0111] Examples of materials that can be used as a light-emitting substance that emits fluorescent light (fluorescent light-emitting substance) in the light-emitting layer 113 include the following: In addition, other fluorescent light-emitting substances can also be used.

[0112] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine )phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-( 10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis(N,N',N'-triphenyl-1,4-phenylenediamine) (abbreviation: DPABPA), N,9 -diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviated as DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA) , 9,10-bis(biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bis(biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyra N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhTD), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhTD), Name: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB),6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyren-diyl)bis[(6-phenylbenzo[b]naphtho]] Examples include N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (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, such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred because of their high hole-trapping properties and excellent luminous efficiency and reliability.

[0113] When a phosphorescent material is used as the light-emitting material in the light-emitting layer 113, examples of materials that can be used include the following.

[0114] Organometallic iridium complexes with a 4H-triazole skeleton, such as tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]) and tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), Organometallic iridium complexes with a 1H-triazole skeleton, such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prpttz1-Me)3]), and fac-tris[1-(2,6-diisopropyl) tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), tris(2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazol-2-yl-κN3}-4-cyanophenyl- Organometallic iridium complexes with an imidazole skeleton, such as (κC)iridium(III) (abbreviation: CNImIr), organometallic iridium complexes with a benzimidazolidene skeleton, such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC)phenyl-κC]iridium(III) (abbreviation: [Ir(cb)3]), and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ] Organometallic iridium complexes with phenylpyridine derivatives bearing electron-withdrawing groups as ligands, such as iridium(III) acetylacetonate (abbreviated as FIr(acac)), are compounds that exhibit blue phosphorescence, with peak emission in the wavelength range from 440 nm to 520 nm.

[0115] 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- Organometallic iridium complexes with a pyrimidine skeleton, such as (2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]) and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), and tris(2-phenylpyridinato-N,C 2’) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’) Iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)), {2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzo furo[2,3-b]pyridin-7-yl-κC}bis{5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviated as Ir(5mtpy-d6)2(mbfpypy-iPr-d4)), [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviated as Ir(ppy)2(mbfpy py-d3)), [2-(4-d3-methyl-5-phenyl-2-pyridinyl-κN2)phenyl-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviated as [Ir(5mppy-d3)2(mdppy-d3)]), [2-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviated as [Ir(ppy Examples include organometallic iridium complexes with a pyridine skeleton, such as [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviated as Ir(ppy)2(mdppy)), and rare earth metal complexes, such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviated as [Tb(acac)3(Phen)]). These compounds primarily exhibit green phosphorescence, with an emission peak in the wavelength range from 500 nm to 600 nm. Organometallic iridium complexes with a pyrimidine skeleton are particularly preferred due to their outstanding reliability and luminous efficiency.

[0116] The red phosphorescent material described above can also be used. In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0117] TADF materials include fullerene and its derivatives, acridine and its derivatives, eosin derivatives, etc. Also available are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP), all of which are shown in the following structural formulas.

[0118] [ka]

[0119] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzPTzn), and 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ), which are shown in the following structural formulas, are also available. Heterocyclic compounds having either or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable. Furthermore, a dibenzofuran skeleton is preferred as a furan skeleton, and a dibenzothiophene skeleton is preferred as a thiophene skeleton.Particularly preferred pyrrole skeletons include an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole skeleton. Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-deficient heteroaromatic ring are both enhanced, thereby reducing the energy difference between the S1 level and the T1 level, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. Examples of π-electron-rich skeletons that can be used include aromatic amine skeletons and phenazine skeletons. Examples of usable π-electron-deficient skeletons include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring or heteroaromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0120] [ka]

[0121] Alternatively, TADF materials may be used, which are capable of extremely fast and reversible intersystem crossing and emit light according to a thermal equilibrium model between singlet and triplet excited states. These TADF materials have an extremely short emission lifetime (excitation lifetime) for TADF materials, and can suppress efficiency decline in the high-brightness region of light-emitting devices. Specifically, materials with the molecular structure shown below can be used.

[0122] [ka]

[0123] TADF materials are materials with a small difference between the S1 and T1 levels, and have the ability to convert triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy (reverse intersystem crossing) using a small amount of thermal energy, allowing for efficient generation of a singlet excited state. Triplet excitation energy can also be converted into light emission.

[0124] Furthermore, exciplexes (also known as exciplexes), which form an excited state with two types of substances, have an extremely small difference between the S1 and T1 levels and function as TADF materials that can convert triplet excitation energy into singlet excitation energy.

[0125] Note that the phosphorescence spectrum observed at low temperatures (for example, from 77 K to 10 K) can be used as an indicator of the T1 level. For a TADF material, when a tangent line is drawn at the base of the short wavelength side of the fluorescence spectrum, and the energy of the wavelength of the extrapolated line is defined as the S1 level, and a tangent line is drawn at the base of the short wavelength side of the phosphorescence spectrum, and the energy of light having the wavelength of the extrapolated line is defined as the T1 level, the difference between the S1 level and the T1 level is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0126] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0127] Examples of the electron-transporting material (corresponding to a first organic compound in one embodiment of the present invention) used as the host material include metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), and organic compounds having a π-electron-deficient heteroaromatic ring. Examples of organic compounds having a π-electron-deficient heteroaromatic ring include 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(4-tert-butylphenyl)-1,3,4- [oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-furan Organic compounds containing heteroaromatic rings with an azole skeleton, such as phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 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: 2mDBTBP DBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 2,4-Bis[4-(1-naphthyl)phenyl]-6-[4-(3-pyridyl)phenyl]pyrimidine (abbreviated as 2,4NP-6PyPPm), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviated as 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-9-yl)phenyl]- organic compounds containing heteroaromatic rings with a diazine skeleton, such as [3-(9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz); organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-tri[(3-pyridyl)phenyl-3-yl]benzene (abbreviation: TmPyPB); organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl]pyridine (abbreviation: 2-(9H-carbazol-2-yl)quinazolin-2-yl)-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz); phenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan- 6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-[3'-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,Examples of suitable organic compounds include those containing heteroaromatic rings with a triazine skeleton, such as [(5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn) and 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn). Among the above, organic compounds containing heteroaromatic rings with a diazine skeleton, organic compounds containing heteroaromatic rings with a pyridine skeleton, and organic compounds containing heteroaromatic rings with a triazine skeleton are preferred due to their high reliability. In particular, organic compounds containing heteroaromatic rings with a diazine (pyrimidine and pyrazine) skeleton and organic compounds containing heteroaromatic rings with a triazine skeleton have high electron transport properties and contribute to reduced driving voltage.

[0128] The hole-transporting material (corresponding to the second organic compound in one embodiment of the present invention) used as the host material can also be an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring. Examples of the organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'- (9-Phenylfluoren-9-yl)triphenylamine (abbreviated as BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl) -4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine Compounds with an aromatic amine skeleton, such as N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-dimethyl-9H-fluoren-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,compounds having a carbazole skeleton such as 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP); compounds having a 3,3'-bicarbazole skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II); 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: D Examples of suitable compounds include compounds having a thiophene skeleton, such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton or a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. Furthermore, the organic compounds listed as examples of materials having hole transport properties in the hole transport layer 112 can also be used as the hole transport material of the host.

[0129] By mixing an electron transport material and a hole transport material, the transport property of the light-emitting layer 113 can be easily adjusted, and the recombination region can be easily controlled. Also, a TADF material can be used as an electron transport material or a hole transport material.

[0130] The TADF materials that can be used as host materials are the same as those listed above. When a TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted to singlet excitation energy through reverse intersystem crossing, and the energy is then transferred to the light-emitting material, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor.

[0131] This is very effective when the luminescent material is a fluorescent luminescent material. In this case, in order to obtain high luminous efficiency, the S1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. In addition, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent luminescent material.

[0132] It is also preferable to use a TADF material that emits light that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material, as this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient light emission.

[0133] Furthermore, to efficiently generate singlet excitation energy from triplet excitation energy through reverse intersystem crossing, carrier recombination is preferred in the TADF material. Furthermore, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to triplet excitation energy in the fluorescent material. To achieve this, the fluorescent material preferably has a protecting group around its luminophore (the skeleton responsible for light emission). The protecting group is preferably a substituent without a π bond, and is preferably a saturated hydrocarbon. Specific examples of the protecting group 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 preferred to have multiple protecting groups. When the cycloalkyl group or trialkylsilyl group has a substituent, examples of the substituent include alkyl groups having 3 to 10 carbon atoms, cycloalkyl groups having 3 to 10 carbon atoms, alkoxy groups having 3 to 10 carbon atoms, silyl groups, amino groups, and halogen groups. Substituents without π-bonds have poor carrier transport properties, allowing for increased distance between the TADF material and the luminophores of fluorescent materials without significantly affecting carrier transport and recombination. Here, the term "luminophores" refers to the atomic group (skeleton) responsible for light emission in fluorescent materials. Lumophores preferably have π-bonded skeletons, preferably contain aromatic rings, and preferably have fused aromatic or heteroaromatic rings. Examples of such luminophores include phenanthrene, stilbene, acridone, phenoxazine, phenothiazine, naphthalene, anthracene, fluorene, chrysene, triphenylene, tetracene, pyrene, perylene, coumarin, quinacridone, and naphthobisbenzofuran skeletons. In particular, fluorescent substances having a naphthalene skeleton, anthracene skeleton, fluorene skeleton, chrysene skeleton, triphenylene skeleton, tetracene skeleton, pyrene skeleton, perylene skeleton, coumarin skeleton, quinacridone skeleton, or naphthobisbenzofuran skeleton are preferred because of their high fluorescence quantum yield.

[0134] When a fluorescent emitting substance is used as the emitting substance, a material having an anthracene skeleton is suitable as the host material. Using a substance having an anthracene skeleton as a host material for a fluorescent emitting substance makes it possible to realize an emitting layer with both excellent luminous efficiency and durability. Substances having an anthracene skeleton used as a host material include diphenylanthracene, dinaphthylanthracene, and phenylnaphthylanthracene skeletons, and in particular, substances having a 9,10-diphenylanthracene skeleton, a 9,10-dinaphthylanthracene skeleton, and a 9-phenyl-10-naphthylanthracene skeleton are preferred due to their chemical stability. Furthermore, host materials having a carbazole skeleton are preferred because of their enhanced hole injection and transport properties. However, host materials containing a benzocarbazole skeleton, in which a benzene ring is further condensed to the carbazole skeleton, are even more preferred because their HOMO level is approximately 0.1 eV shallower than that of host materials having a carbazole skeleton, facilitating hole intrusion. In particular, when the host material contains a dibenzocarbazole skeleton, the HOMO level is shallower by about 0.1 eV than that of a host material having a carbazole skeleton, making it easier for holes to enter, and it also has excellent hole transport properties and high heat resistance, making it suitable. Therefore, a more preferred host material is a substance that simultaneously has a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). Note that, from the viewpoint of the hole injection / 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 (abbreviation: PCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 9-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]-10-phenylanthracene (abbreviation: CzPAP), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4'-(9-phenyl-9H-fluoren-9-yl)biphenyl-4-yl]anthracene (abbreviation: FLPPA), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,β-ADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 4-[3-(9,10-diphenyl -2-anthryl)phenyl]dibenzofuran (abbreviation: 2mDBFPPA-II), 2-(10-phenyl-9-anthryl)benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 9-(1-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: αN-mβNPAnth), 1-{4-[10 -(biphenyl-4-yl)-9-anthryl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), 7-(10-phenyl-9-anthryl)benzo[b]naphtho[2,1-d]furan (abbreviation: aBnfPhA), 2-(10-phenyl-9-anthryl)dibenzofuran (abbreviation: DBfPhA), 2-[10-(biphenyl-2-yl)-9-anthryl]benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(I Examples include 2-[10-(biphenyl-4-yl)-9-anthryl]benzo[b]naphtho[2,3-d]furan (abbreviated as Bnf(II)BPhA), 2-[10-(biphenyl-3-yl)-9-anthryl]benzo[b]naphtho[2,3-d]furan (abbreviated as Bnf(II)mBPhA), and 2-[10-(biphenyl-3-yl)-9-anthryl]benzo[b]naphtho[1,2-d]furan (abbreviated as Bnf(6)mBPhA). In particular, CzPA, CzPAP, cgDBCzPA, 2mBnfPPA, PCzPA, αN-mβNPAnth, and 2αN-αNPAnth are preferred choices due to their excellent properties.

[0135] A phosphorescent material can be used as part of the mixed material. The phosphorescent material can be used as an energy donor that provides excitation energy to a fluorescent material when the fluorescent material is used as a light-emitting material.

[0136] The mixed materials may also form an exciplex. The exciplex is preferably selected from a combination that forms an exciplex that emits light that overlaps with the lowest-energy absorption band of the light-emitting material, because this allows for smooth energy transfer and efficient light emission. Furthermore, this configuration is also preferable because it reduces the driving voltage.

[0137] At least one of the materials forming the exciplex may be a phosphorescent material, which allows efficient conversion of triplet excitation energy into singlet excitation energy through reverse intersystem crossing.

[0138] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of the hole-transporting material is equal to or higher than the HOMO level of the electron-transporting material, and it is also preferable that the LUMO level of the hole-transporting material is equal to or higher than the LUMO level of the electron-transporting material.

[0139] The formation of exciplexes can be confirmed by, for example, comparing the emission spectra of a material with hole transport properties, a material with electron transport properties, and a mixed film of these materials and observing the phenomenon that the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak at longer wavelengths). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a material with hole transport properties, a material with electron transport properties, and a mixed film of these materials and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lived component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL can also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of a material with hole transport properties, a material with electron transport properties, and a mixed film of these materials and observing differences in transient response.

[0140] The light-emitting layer 113 can be formed by a vapor deposition method (including a vacuum deposition method), an inkjet method, a coating method, gravure printing, etc. In addition to the materials described above, the light-emitting layer 113 may contain inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymers, etc.).

[0141] Furthermore, when a fluorescent emitting substance is used in the light-emitting layer, the T1 level of the host material of the light-emitting layer is preferably lower than the T1 level of the compound in the adjacent carrier transport layer (hole transport layer or electron transport layer). In this case, the luminous efficiency of the light-emitting device can be improved. The T1 level of the host material is preferably at least 0.2 eV lower, more preferably at least 0.5 eV lower, than the T1 level of the compound in the adjacent carrier transport layer. When a fluorescent emitting substance is used in the light-emitting layer, the T1 level of the host material of the light-emitting layer is preferably lower than the T1 level of the fluorescent emitting substance. This configuration allows T1 excitation energy to be transferred from the surrounding materials to the host material of the light-emitting layer, increasing the density of the T1 excited state of the host material of the light-emitting layer and facilitating TTA in the host material, thereby improving the luminous efficiency. Since the deuterium-containing compound according to one embodiment of the present invention can increase the T1 level, it is preferably laminated with the light-emitting layer. Since a compound containing an anthracene skeleton can lower the T1 level, it is suitable as an example of a host material. Therefore, stacking a carrier-transport layer using a compound having deuterium according to one embodiment of the present invention and a light-emitting layer using a compound having an anthracene skeleton as a host material is suitable for providing a device with high emission efficiency, although the host material is not limited to those having an anthracene skeleton.

[0142] On the other hand, if the T1 level of the host material is too small compared to the T1 level of the compound in the carrier transport layer (the difference in T1 levels is large), the exciton density at the interface between the light-emitting layer and the carrier transport layer increases, and exciton deactivation may result in reduced reliability. In one embodiment of the present invention, the use of deuterated compounds for the compound in the hole transport layer (carrier transport layer) and the host material in the light-emitting layer suppresses compound degradation, thereby enabling a long life for the light-emitting device even when the difference in T1 levels is large. Furthermore, reliability can be further improved when the difference between the T1 level of the compound in the carrier transport layer and the T1 level of the host material in the light-emitting layer is 1.0 eV or less, preferably 0.7 eV or less, and more preferably 0.5 eV or less.

[0143] The HOMO level of the host material of the light-emitting layer is preferably lower than the HOMO level of the compound in the adjacent hole-transport layer. In this case, holes generated in the hole-injection layer can be efficiently transported to the light-emitting layer via the hole-transport layer, thereby providing a light-emitting device with high hole transportability and therefore high luminous efficiency. Specifically, the HOMO level of the host material of the light-emitting layer is preferably lower than the HOMO level of the compound in the adjacent hole-transport layer by at least 0.1 eV, more preferably by at least 0.2 eV. However, since a large difference in HOMO levels may reduce the injection of holes into the light-emitting layer, the difference between the HOMO level of the host material and the HOMO level of the compound in the adjacent hole-transport layer is preferably 0.5 eV or less, more preferably 0.3 eV or less. A suitable material for achieving such a HOMO level relationship is to use a compound containing deuterium according to one embodiment of the present invention as the hole-transport layer and a compound containing an anthracene skeleton as the host material for the light-emitting layer.

[0144] The organic compound used as the host material preferably contains deuterium, and some or all of the hydrogen atoms in the organic compound may be deuterium. The deuteration rate for each is preferably 80% or higher, more preferably 90% or higher. Furthermore, when the organic compound has a structure containing only hydrocarbons (referring to a hydrocarbon ring or hydrocarbon skeleton, such as a benzene ring, naphthalene ring, or anthracene ring), the hydrocarbon ring preferably contains deuterium. Compounds such as halides are readily available as deuterium-containing hydrocarbon rings. Therefore, when an organic compound is partially or entirely composed of a hydrocarbon ring, using a compound in which the hydrocarbon ring contains deuterium can reduce production costs. Furthermore, when the organic compound has a hydrocarbon ring and a heteroaromatic ring (such as a carbazole ring, a diazine ring, a triazine ring, a dibenzofuran ring, or a dibenzothiophene ring), both the hydrocarbon ring and the heteroaromatic ring may contain deuterium, or only one of them may contain deuterium. Containing deuterium only in the hydrocarbon ring is particularly preferred, as it can reduce production costs.

[0145] <Hole injection layer> In Figure 1(A) and Figures 2(A) to 2(E), the hole injection layers (111, 111a, 111b) are layers that inject holes from the first electrode 101, which is an anode, and the charge generation layers (106, 106a, 106b) into the organic compound layers (103, 103a, 103b), and are layers that contain an organic acceptor material and a material with high hole injection properties.

[0146] The hole injection layer (111, 111a, 111b) can be formed using a compound having an electron-withdrawing group (a halogen group or a cyano group), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. In particular, compounds such as HAT-CN, in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms, are preferred because of their thermal stability. Radialene derivatives having an electron-withdrawing group (especially a halogen group such as a fluoro group or a cyano group) are also preferred because of their extremely high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidenetris(4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile) (abbreviation: Rad), α,α',α''-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. As the substance having acceptor properties, in addition to the organic compounds described above, molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. can be used.In addition, the hole injection layers (111, 111a, 111b) can also be formed using phthalocyanine compounds such as phthalocyanine (abbreviated as HPc), phthalocyanine complex compounds such as copper phthalocyanine (CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) and N,N'-bis[4-bis(3-methylphenyl)aminophenyl]-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviated as DNTPD), or polymers such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (abbreviated as PEDOT / PSS). Acceptor materials can extract electrons from the adjacent hole transport layer (or hole transport material) when an electric field is applied.

[0147] Among substances having acceptor properties, organic compounds having acceptor properties are easy to use because they can be easily vapor-deposited and formed into a film due to their low vapor deposition temperature.

[0148] Furthermore, a composite material in which a material having hole transport properties contains the above-mentioned acceptor substance can also be used for the hole injection layers (111, 111a, 111b). Note that by using a composite material in which a material having hole transport properties contains an acceptor substance, a material for forming an electrode can be selected regardless of the work function. In other words, not only a material with a high work function but also a material with a low work function can be used for the anode (first electrode 101).

[0149] As a material having hole transport properties to be used in the composite material, various organic compounds such as aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that as a material having hole transport properties to be used in the composite material, -6 cm 2 A substance having a hole mobility of 1 / Vs or more is preferred. Specific examples of organic compounds that can be used as a material having a hole transport property in a composite material are listed below.

[0150] Examples of aromatic amine compounds that can be used in composite materials include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis[4-bis(3-methylphenyl)aminophenyl]-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B). Specific examples of the carbazole derivative include 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenyl Carbazole (abbreviation: PCzPCN1), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, etc. can be used.Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert- Examples of suitable anthracene include butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, and 2,5,8,11-tetra(tert-butyl)perylene. Pentacene and coronene may also be used. The aromatic hydrocarbon having a vinyl group may also have a vinyl skeleton. Examples of the aromatic hydrocarbon having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA). Note that the organic compound of one embodiment of the present invention can also be used.

[0151] In addition, polymer compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used.

[0152] The hole-transporting material used in the composite material preferably has at least one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, the material may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. It is preferable that these organic compounds have an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of a light-emitting device with a long lifetime. Specific examples of such organic compounds include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-i 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 Ran-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: : BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-Diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-(5;2' -binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: TPBiAβNBi), Phenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine Phenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviated as BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9 N-(4-biphenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBASF), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluoren]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine Examples of suitable amines include PCBBiF (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine.

[0153] Note that the material having hole-transporting properties used in the composite material is more preferably a substance having a relatively deep HOMO level of -5.7 eV or more and -5.2 eV or less. When the material having hole-transporting properties used in the composite material has a relatively deep HOMO level, injection of holes into the hole-transport layer 112 becomes easy, and a light-emitting device with a long lifetime can be easily obtained. Furthermore, when the material having hole-transporting properties used in the composite material has a relatively deep HOMO level, induction of holes is appropriately suppressed, and a light-emitting device with a long lifetime can be obtained.

[0154] The refractive index of the layer can be reduced by further mixing an alkali metal or alkaline earth metal fluoride with the composite material (preferably with an atomic ratio of fluorine atoms of 20% or more in the layer). This also allows a layer with a low refractive index to be formed inside the organic compound layer 103, thereby improving the external quantum efficiency of the light-emitting device. Furthermore, the hole-transporting material preferably contains an alkyl group. The presence of an alkyl group can reduce the refractive index. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, isopentyl, sec-pentyl, tert-pentyl, neopentyl, hexyl, isohexyl, n-hexyl, 3-methylpentyl, 2-methylpentyl, 2-ethylbutyl, 1,2-dimethylbutyl, and 2,3-dimethylbutyl. It is particularly preferable for the alkyl group to contain multiple alkyl groups. By stacking a material having a low refractive index and hole transporting properties with a layer containing a compound having deuterium according to one embodiment of the present invention, emitted light can be efficiently extracted to the outside, thereby improving the external quantum efficiency of the light-emitting device. Furthermore, when the external quantum efficiency is increased, the current density required to obtain the required luminance decreases, thereby improving reliability in a continuous driving test. For example, when the material having hole transporting properties has one methyl group, the refractive index (for example, the ordinary refractive index n о) can be reduced by 0.02. Therefore, the refractive index can be further reduced by having multiple alkyl groups. For example, the number of alkyl groups is preferably 2 or more, 4 or more, 6 or more, or 8 or more. However, since too many alkyl groups may be prone to decomposition during vapor deposition and may reduce carrier mobility, it is preferable to keep the number of alkyl groups to 10 or less. In particular, compounds having multiple methyl groups or tert-butyl groups or both are suitable for achieving both high external quantum efficiency and high carrier mobility.

[0155] By forming the hole injection layers (111, 111a, 111b), the hole injection property is improved, and a light emitting device with a low driving voltage can be obtained.

[0156] <Hole transport layer> 1A and 2A to 2E, the hole-transporting layers (112, 112a, 112b) are layers containing a hole-transporting material, and the hole-transporting materials exemplified as the materials for the hole-injection layers (111, 111a, 111b) can be used. The hole-transporting layers (112, 112a, 112b) have a function of transporting holes injected into the hole-injection layers (111, 111a, 111b) to the light-emitting layers (113, 113a, 113b), and therefore preferably have a HOMO level that is the same as or close to the HOMO level of the hole-injection layers (111, 111a, 111b).

[0157] Also, 1×10 -6 cm 2 It is preferable that the layer contains a substance having a hole mobility of 1 / Vs or more. However, other substances having a hole mobility may be used as long as they have a higher hole transporting property than an electron transporting property. Note that the layer containing the substance having a high hole transporting property may be a single layer or may be a stack of two or more layers containing the above-mentioned substance.

[0158] For example, when the hole transport layer has a laminated structure, it is preferable to use a material with high electron blocking properties on the side in contact with the light-emitting layer. Specifically, when the LUMO level of the hole transport layer provided in contact with the light-emitting layer is higher than the LUMO level of the material (at least the host material) constituting the light-emitting layer, the hole transport layer may also exhibit excellent function as an electron blocking layer. In this case, it is preferable from the viewpoint of improving luminous efficiency that the LUMO level of the hole transport layer is higher than the LUMO level of the material (at least the host material) constituting the light-emitting layer by 0.3 eV or more, preferably 0.5 eV or more.

[0159] Materials that can be used for the hole transport layer (112, 112a, 112b) include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BP AFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4 ''-(9-Phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9 ,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBA βNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviated as BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviated as BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviated as BBAαNβNB-03), 4,4'-diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviated as 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)triphenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-Diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviated as YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(biphenyl-4-yl)amine (abbreviated as YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviated as YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1 -naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (mPDBfBNBN), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N- Compounds with an aromatic amine skeleton such as bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 9,9'-diphenyl-9H,9'H-3,Compounds with a carbazole skeleton, such as 3'-bicarbazole (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), and 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4- Examples of the compound include compounds having a thiophene skeleton, such as 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the compounds mentioned above, compounds having an aromatic amine skeleton or a carbazole skeleton are preferred because they have good reliability, high hole-transport properties, and contribute to a reduction in driving voltage. Note that the substances listed as the materials having hole-transport properties used in the composite material of the hole-injection layer 111 can also be suitably used as materials for the hole-transport layer 112. ,

[0160] ≪Electron transport layer≫ In Figure 1(A) and Figures 2(A) to 2(E), the electron transport layer (114, 114a, 114b) has a function of transporting electrons injected from the other of the pair of electrodes (the first electrode 101 or the second electrode 102) to the light-emitting layer 113 via the electron injection layer (115, 115a, 115b).

[0161] The electron transporting material is an organic compound having electron transport properties, and the electron mobility at a square root of the electric field strength [V / cm] of 600 is 1×10 -6cm 2 A substance having an electron mobility of 1 / Vs or higher is preferred. Electron mobility can be measured in the same manner as in JP 2020-096171 A. The configuration of the electron-only device used for measurement can be appropriately selected based on the device configuration that facilitates electron injection into the compound whose electron mobility is being measured. Substances other than these can be used as long as they have a higher electron transport property than holes. The organic compound is preferably an organic compound having a π-electron-deficient heteroaromatic ring. Examples of organic compounds having a π-electron-deficient heteroaromatic ring include, for example, one or more of an organic compound having a heteroaromatic ring with an azole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0162] Specific examples of organic compounds having a π-electron-deficient heteroaromatic ring that can be used in the electron transport layer include 2-(4-biphenyl)-5-(4-tert-butyl-phenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl]benzene]-2-yl]benzo[4-(5-phenyl-1,3,4-oxadiazol ... Organic compounds with an azole skeleton, such as 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]- Organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), ... '-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[3'-(dibenzothiophen-4-yl)biphenyl -4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9 H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 8-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfp m), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviated as 2,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviated as 2,6(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-Bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), 2,4-bis[4-(1-naphthyl)phenyl]-6-[4-(3-pyridyl)phenyl]pyrimidine (abbreviated as 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviated as 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazol-2-yl Organic compounds with a diazine skeleton, such as benzo[b]naphtho[1,2-d]furan-8-ylphenyl]phenyl, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (mFBPTzn), 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (BP-SFTzn), and 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (BP-SFTzn). ,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), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole mPCCzPTzn-02), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthryl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3 Examples of organic compounds having a triazine skeleton include 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), and 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn). Among the above, organic compounds having a heteroaromatic ring with a diazine skeleton, organic compounds having a heteroaromatic ring with a pyridine skeleton, and organic compounds having a heteroaromatic ring with a triazine skeleton are preferred due to their high reliability. In particular, organic compounds containing heteroaromatic rings with a diazine (pyrimidine and pyrazine) skeleton and organic compounds containing heteroaromatic rings with a triazine skeleton have high electron transport properties and contribute to reducing driving voltages.

[0163] Note that stacking an electron-transport layer containing an organic compound having an azine skeleton, a light-emitting layer containing an organic compound having an anthracene skeleton, and a hole-transport layer containing a compound having deuterium according to one embodiment of the present invention improves the reliability of continuous operation of the light-emitting device and reduces the driving voltage. Furthermore, stacking a material having a low refractive index and hole-transporting properties can provide a light-emitting device with improved external quantum efficiency. Therefore, the current density required to achieve high luminance can be reduced, thereby enabling the provision of a light-emitting device with reduced power consumption. In particular, stacking these layers together, i.e., stacking a hole-transport layer containing an organic compound having an alkyl group, a hole-transport layer containing a compound having deuterium according to one embodiment of the present invention, a light-emitting layer containing an organic compound having an anthracene skeleton, and an electron-transport layer containing an organic compound having a triazine skeleton, can improve the characteristics of the light-emitting device and provide a light-emitting device with improved heat resistance or stability.

[0164] The electron transporting layer (114, 114a, 114b) may be a single layer or may be a stack of two or more layers containing the above substance.

[0165] Furthermore, a layer for controlling the movement of electron carriers may be provided between the electron transport layer (114, 114a, 114b) and the light-emitting layer (113, 113a, 113b). This layer is made by adding a small amount of a substance with high electron trapping properties to a material with high electron transport properties as described above, and by suppressing the movement of electron carriers, it becomes possible to adjust the carrier balance. This type of configuration is highly effective in suppressing problems (e.g., a reduction in device life) caused by electrons passing through the light-emitting layer.

[0166] ≪Electron injection layer≫ In FIG. 1A and FIG. 2A to FIG. 2E, the electron injection layers (115, 115a, 115b) have a function of promoting electron injection by reducing the barrier to electron injection from the second electrode 102.

[0167] Furthermore, for example, Group 1 metals, Group 2 metals, or oxides, halides, carbonates, etc. thereof can be used. Furthermore, a composite material of the above-mentioned electron transporting material and a material that exhibits electron donating properties can also be used. Examples of materials that exhibit electron donating properties include Group 1 metals, Group 2 metals, or oxides thereof. Specifically, lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2), lithium oxide (LiO x Alkali metals, alkaline earth metals, or compounds thereof such as fluoride (ErF3) can be used. Rare earth metal compounds such as erbium fluoride (ErF3) can also be used. Electrides can also be used for the electron injection layer 115. Examples of such electrides include a substance in which a mixed oxide of calcium and aluminum is doped with a high concentration of electrons. Substances that can be used for the electron transport layers (114, 114a, 114b) can also be used for the electron injection layers (115, 115a, 115b).

[0168] The electron injection layer (115, 115a, 115b) may also be made of a composite material containing an organic compound and an electron donor (donor). Such composite materials have excellent electron injection and transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent at transporting the generated electrons. Specifically, the above-mentioned substances constituting the electron transport layer 114 (metal complexes, heteroaromatic compounds, etc.) can be used. The electron donor may be any substance that exhibits electron donating properties to the organic compound. Specifically, alkali metals, alkaline earth metals, or rare earth metals are preferred, such as lithium, sodium, cesium, magnesium, calcium, erbium, and ytterbium. Alkali metal oxides or alkaline earth metal oxides are preferred, such as lithium oxide, calcium oxide, and barium oxide. Lewis bases such as magnesium oxide can also be used. Organic compounds such as tetrathiafulvalene (TTF) can also be used.

[0169] The light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer can be formed by vapor deposition (including vacuum deposition), inkjet printing, coating, gravure printing, etc. In addition to the materials described above, the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer may be made of inorganic compounds such as quantum dots or polymeric compounds (oligomers, dendrimers, polymers, etc.).

[0170] Quantum dots may be colloidal quantum dots, alloy quantum dots, core-shell quantum dots, core quantum dots, etc. Quantum dots containing elements from groups 2 and 16, 13 and 15, 13 and 17, 11 and 17, or 14 and 15 may also be used. Quantum dots containing elements such as cadmium (Cd), selenium (Se), zinc (Zn), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), arsenic (As), and aluminum (Al) may also be used.

[0171] <Pair of electrodes> The first electrode 101 and the second electrode 102 function as an anode or a cathode of the light-emitting device. The first electrode 101 and the second electrode 102 can be formed using a metal, an alloy, a conductive compound, or a mixture or stack of these materials.

[0172] It is preferable that one of the first electrode 101 and the second electrode 102 is formed of a conductive material that has a light-reflecting function. Examples of the conductive material include aluminum (Al) and alloys containing Al. Examples of alloys containing Al include alloys containing Al and L (L represents one or more of titanium (Ti), neodymium (Nd), nickel (Ni), and lanthanum (La)), such as alloys containing Al and Ti, or Al, Ni, and La. Aluminum has low resistance and high light reflectivity. Furthermore, aluminum is abundant in the earth's crust and inexpensive, so the use of aluminum can reduce the production costs of light-emitting devices. Alternatively, silver (Ag) or an alloy containing Ag and N (N represents one or more of yttrium (Y), Nd, magnesium (Mg), ytterbium (Yb), Al, Ti, gallium (Ga), zinc (Zn), indium (In), tungsten (W), manganese (Mn), tin (Sn), iron (Fe), Ni, copper (Cu), palladium (Pd), iridium (Ir), or gold (Au)) may be used. Examples of alloys containing silver include alloys containing silver, palladium, and copper, alloys containing silver and copper, alloys containing silver and magnesium, alloys containing silver and nickel, alloys containing silver and gold, and alloys containing silver and ytterbium. Other transition metals that can be used include tungsten, chromium (Cr), molybdenum (Mo), copper, and titanium.

[0173] Furthermore, light emitted from the light-emitting layer is extracted through one or both of the first electrode 101 and the second electrode 102. Therefore, at least one of the first electrode 101 and the second electrode 102 is preferably formed from a conductive material that has a light-transmitting function. The conductive material has a visible light transmittance of 40% or more and 100% or less, preferably 60% or more and 100% or less, and a resistivity of 1×10 -2 Examples include conductive materials with a resistance of Ω·cm or less.

[0174] The first electrode 101 and the second electrode 102 may be formed of a conductive material that has both a light transmitting and a light reflecting function. The conductive material has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10 -2 Examples of suitable materials include conductive materials with a resistivity of Ω·cm or less. For example, the film can be formed using one or more conductive metals, alloys, conductive compounds, etc. Specifically, metal oxides such as indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide (abbreviated as ITSO), indium zinc oxide, titanium-containing indium tin oxide, indium titanium oxide, and indium oxide containing tungsten oxide and zinc oxide can be used. Alternatively, a thin metal film that is light-transmitting (preferably, a thickness of 1 nm to 30 nm) can be used. Examples of suitable metals include Ag. Examples of suitable alloys include alloys of Ag and Al, Ag and Mg, Ag and Au, and Ag and Yb.

[0175] In this specification and the like, the material having the function of transmitting light may be any material that has the function of transmitting visible light and is conductive, and includes, for example, oxide conductors such as ITO as described above, as well as oxide semiconductors or organic conductors containing organic substances. Examples of organic conductors containing organic substances include composite materials obtained by mixing an organic compound with an electron donor, and composite materials obtained by mixing an organic compound with an electron acceptor. In addition, inorganic carbon-based materials such as graphene may also be used. The resistivity of the material is preferably 1×10 5 Ω·cm or less, more preferably 1×10 4 Ω·cm or less.

[0176] Alternatively, one or both of the first electrode 101 and the second electrode 102 may be formed by stacking a plurality of the above materials.

[0177] Furthermore, in order to improve light extraction efficiency, a material having a higher refractive index than an electrode having a light-transmitting function may be formed in contact with the electrode. Such a material may be any material that transmits visible light, and may or may not be conductive. Examples of such a material include oxide semiconductors and organic materials, as well as the oxide conductors described above. Examples of organic materials include the materials exemplified for the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer. Inorganic carbon-based materials or thin metal films that transmit light may also be used, and multiple layers of several nanometers to several tens of nanometers thick may be stacked.

[0178] When the first electrode 101 or the second electrode 102 functions as a cathode, it is preferable that the electrode be made of a material with a small work function (3.8 eV or less). For example, elements belonging to Group 1 or 2 of the periodic table (alkali metals such as lithium, sodium, and cesium, alkaline earth metals such as calcium and strontium, magnesium, etc.), alloys containing these elements (e.g., Ag and Mg, Al and Li), rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, alloys containing aluminum and silver, etc. can be used.

[0179] When the first electrode 101 or the second electrode 102 is used as an anode, it is preferable to use a material with a large work function (4.0 eV or more).

[0180] The first electrode 101 and the second electrode 102 may be a laminate of a conductive material having a light-reflecting function and a conductive material having a light-transmitting function. In this case, the first electrode 101 and the second electrode 102 are preferable because they can adjust the optical path so that desired light from each light-emitting layer can be resonated and the light of that wavelength can be intensified.

[0181] The first electrode 101 and the second electrode 102 can be formed by any suitable method, such as sputtering, vapor deposition, printing, coating, MBE (Molecular Beam Epitaxy), CVD, pulsed laser deposition, or ALD (Atomic Layer Deposition).

[0182] <Charge generation layer (intermediate layer)> In FIGS. 2B and 2D, the charge generation layer 106 functions to inject electrons into the organic compound layer 103a and holes into the organic compound layer 103b when a voltage is applied between the first electrode (anode) 101 and the second electrode (cathode) 102. The charge generation layer 106 may be a layer in which an electron acceptor is added to a hole transporting material (also referred to as a p-type layer) or an electron donor is added to an electron transporting material (also referred to as an electron injection buffer layer). Alternatively, both of these layers may be stacked. Furthermore, an electron relay layer may be provided between the p-type layer and the electron injection buffer layer. Forming the charge generation layer 106 using the above-described materials can suppress an increase in driving voltage when organic compound layers including a light-emitting layer are stacked.

[0183] 2(E), when a voltage is applied between the first electrode (anode) 101 and the second electrode (cathode) 102, the charge generation layer 106a has a function of injecting electrons into the organic compound layer 103a and injecting holes into the organic compound layer 103b, and the charge generation layer 106b has a function of injecting electrons into the organic compound layer 103b and injecting holes into the organic compound layer 103c. Note that the description of the charge generation layer 106a and the charge generation layer 106b is omitted because they are the same as those of the charge generation layer 106.

[0184] When the charge generation layer 106, the charge generation layer 106a, and the charge generation layer 106b have a structure (p-type layer) in which an electron acceptor is added to a hole-transporting material that is an organic compound, the hole-transporting material described in this embodiment can be used as the hole-transporting material. Examples of the electron acceptor include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, α,α',α''-1,2,3-cyclopropanetriylidenetris(4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile) (abbreviation: Rad), and the like. Examples of the electron acceptor include oxides of metals belonging to Groups 4 to 8 of the periodic table. Specific examples include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide. The acceptor materials described above may also be used. The p-type layer may be formed as a mixed film by mixing materials, or as a laminate of single films containing each material.

[0185] In addition, when the charge generation layer 106, the charge generation layer 106a, and the charge generation layer 106b have a structure in which an electron donor is added to an electron transporting material (electron injection buffer layer), the electron transporting material described in this embodiment can be used.

[0186] As the electron donor, alkali metals, alkaline earth metals, rare earth metals, or metals belonging to Groups 2 and 13 of the periodic table, as well as oxides and carbonates thereof, can be used. Specifically, lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium oxide (LiO), cesium carbonate, etc. can be preferably used. Alternatively, an organic compound such as tetrathianaphthacene can be used as the electron donor.

[0187] When an electron relay layer is provided between the p-type layer and the electron injection buffer layer in the charge generation layer 106, the charge generation layer 106a, or the charge generation layer 106b, the electron relay layer contains at least a substance having electron transport properties and functions to prevent interaction between the electron injection buffer layer and the p-type layer and smoothly transfer electrons. The LUMO level of the substance having electron transport properties contained in the electron relay layer is preferably between the LUMO level of the acceptor substance in the p-type layer and the LUMO level of the substance having electron transport properties contained in the electron transport layer in contact with the charge generation layer 106. The specific energy level of the LUMO level of the substance having electron transport properties used in the electron relay layer is −5.0 eV or higher, preferably −5.0 eV or higher and −3.0 eV or lower. Note that the substance having electron transport properties used in the electron relay layer is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0188] Although Figure 2(D) shows a structure in which the organic compound layer 103 has two layers, that is, the organic compound layer 103a and the organic compound layer 103b are stacked, a stack structure of organic compound layers including three or more light-emitting layers may be formed by providing a charge generation layer between different light-emitting layers, and Figure 2(E) shows a structure in which organic compound layers including three light-emitting layers are stacked.

[0189] <Cap layer> Although not shown in FIGS. 2A to 2E, a capping layer may be provided on the second electrode 102 of the light-emitting device. For example, a material with a high refractive index can be used for the capping layer. By providing the capping layer on the second electrode 102, the extraction efficiency of light emitted from the second electrode 102 can be improved.

[0190] Specific examples of materials that can be used for the cap layer include 5,5'-diphenyl-2,2'-di-5H-[1]benzothieno[3,2-c]carbazole (abbreviation: BisBTc) and 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II).

[0191] <Substrate> The light-emitting device according to one embodiment of the present invention may be fabricated over a substrate made of glass, plastic, etc. The order of fabrication on the substrate may be from the first electrode 101 side or from the second electrode 102 side.

[0192] Note that, as a substrate on which a light-emitting device according to one embodiment of the present invention can be formed, for example, glass, quartz, or plastic can be used. A flexible substrate may also be used. A flexible substrate is a substrate that can be bent (flexible), and examples thereof include a plastic substrate made of polycarbonate or polyarylate. Films, inorganic vapor-deposited films, and the like can also be used. Note that other materials may be used as long as they function as a support in the manufacturing process of the light-emitting device and the optical device. Alternatively, materials that have a function of protecting the light-emitting device and the optical device may be used.

[0193] For example, in this specification, a light-emitting device can be formed using various substrates. The type of substrate is not particularly limited. Examples of such substrates include semiconductor substrates (e.g., single-crystal substrates such as silicon substrates), SOI substrates, glass substrates, quartz substrates, plastic substrates, metal substrates, stainless steel substrates, substrates with stainless steel foil, tungsten substrates, substrates with tungsten foil, flexible substrates, laminated films, cellulose nanofibers (CNF) containing fibrous materials, paper, and base films. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, and soda-lime glass. Examples of flexible substrates, laminated films, and base films include the following: plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Another example is acrylic resin. Another example is polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride. Other examples include resins such as polyamide, polyimide, aramid, and epoxy, inorganic vapor-deposited films, and papers.

[0194] Alternatively, a flexible substrate may be used as the substrate, and the light-emitting device may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light-emitting device. The release layer can be used to separate the light-emitting device from the substrate after it has been partially or entirely completed and transfer it to another substrate. In this case, the light-emitting device can be transferred to a substrate with poor heat resistance or a flexible substrate. The release layer may be, for example, a laminated structure of inorganic films such as a tungsten film and a silicon oxide film, or a structure in which a resin film such as polyimide is formed on a substrate.

[0195] That is, a light-emitting device may be formed using a certain substrate, and then the light-emitting device may be transferred to another substrate, and the light-emitting device may be disposed on the other substrate. In addition to the substrates mentioned above, examples of the substrate onto which the light-emitting device may be transferred include a cellophane substrate, a stone substrate, a wood substrate, a cloth substrate (including natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester), or recycled fibers (acetate, cupra, rayon, recycled polyester)), a leather substrate, or a rubber substrate. By using these substrates, a light-emitting device that is durable, highly heat-resistant, lightweight, or thin can be obtained.

[0196] Alternatively, a field effect transistor (FET) may be formed on the substrate, and a light-emitting device may be fabricated on an electrode electrically connected to the FET. This allows fabrication of an active matrix display device in which the FET controls the driving of the light-emitting device.

[0197] Note that one embodiment of the present invention has been described in this embodiment. Alternatively, another embodiment of the present invention will be described. However, one embodiment of the present invention is not limited thereto. That is, various embodiments of the present invention are described in this embodiment and the other embodiments, and therefore one embodiment of the present invention is not limited to a specific embodiment. For example, although an example in which the present invention is applied to a light-emitting device has been described as one embodiment of the present invention, one embodiment of the present invention is not limited thereto. For example, depending on the circumstances or the situation, one embodiment of the present invention does not need to be applied to a light-emitting device. Alternatively, for example, one embodiment of the present invention has a first organic compound, a second organic compound, and a guest material capable of converting triplet excitation energy into light emission, and the LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, and the HOMO level of the first organic compound is lower than the HOMO level of the second organic compound. However, one embodiment of the present invention is not limited thereto. Depending on the circumstances or the situation, in one embodiment of the present invention, for example, the LUMO level of the first organic compound does not need to be lower than the LUMO level of the second organic compound. Alternatively, the HOMO level of the first organic compound does not have to be lower than the HOMO level of the second organic compound. Alternatively, for example, in one embodiment of the present invention, the first organic compound and the second organic compound form an exciplex. However, this embodiment is not limited to this example. Depending on the circumstances, or depending on the situation, in one embodiment of the present invention, the first organic compound and the second organic compound do not have to form an exciplex. Alternatively, for example, in one embodiment of the present invention, the LUMO level of the guest material is higher than the LUMO level of the first organic compound and lower than the HOMO level of the second organic compound. However, this embodiment is not limited to this example. Depending on the circumstances, or depending on the situation, in one embodiment of the present invention, the LUMO level of the guest material does not have to be higher than the LUMO level of the first organic compound. Alternatively, the HOMO level of the guest material does not have to be lower than the HOMO level of the second organic compound.

[0198] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0199] (Embodiment 2) 3A and 3B, a plurality of light-emitting devices 130 are formed over an insulating layer 175 to form a display device. In this embodiment, a display device according to one embodiment of the present invention will be described in detail.

[0200] The display device 100 has a pixel section 177 in which a plurality of pixels 178 are arranged in a matrix. The pixel 178 has a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0201] In this specification and the like, when describing matters common to, for example, the subpixels 110R, 110G, and 110B, they may be referred to as the subpixels 110. When describing matters common to other components distinguished by alphabets, they may also be described using symbols without the alphabets.

[0202] The sub-pixel 110R emits red light, the sub-pixel 110G emits green light, and the sub-pixel 110B emits blue light. This allows an image to be displayed in the pixel unit 177. In this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are described as an example, but combinations of sub-pixels of other colors may also be used. The number of sub-pixels is not limited to three, and may be four or more. Examples of four sub-pixels include sub-pixels of four colors: R, G, B, and white (W); sub-pixels of four colors: R, G, B, and yellow (Y); and sub-pixels of R, G, B, and infrared (IR).

[0203] In this specification, the row direction may be referred to as the X direction, and the column direction may be referred to as the Y direction. The X direction and the Y direction intersect, for example, perpendicularly.

[0204] 3A shows an example in which sub-pixels of different colors are arranged side by side in the X direction, and sub-pixels of the same color are arranged side by side in the Y direction. Note that sub-pixels of different colors may also be arranged side by side in the Y direction, and sub-pixels of the same color may also be arranged side by side in the X direction.

[0205] A connection portion 140 may be provided outside the pixel portion 177, and a region 141 may be provided. The region 141 is provided between the pixel portion 177 and the connection portion 140. The region 141 is provided with an organic compound layer 103. Furthermore, the connection portion 140 is provided with a conductive layer 151C.

[0206] 3A shows an example in which the region 141 and the connection portion 140 are located on the right side of the pixel portion 177, but the positions of the region 141 and the connection portion 140 are not particularly limited. The region 141 and the connection portion 140 may be singular or plural.

[0207] Fig. 3(B) is an example of a cross-sectional view taken along dashed line A1-A2 in Fig. 3(A). As shown in Fig. 3(B), the display device 100 includes an insulating layer 171, a conductive layer 172 on the insulating layer 171, an insulating layer 173 on the insulating layer 171 and on the conductive layer 172, an insulating layer 174 on the insulating layer 173, and an insulating layer 175 on the insulating layer 174. The insulating layer 171 is provided on a substrate (not shown). The insulating layer 175, the insulating layer 174, and the insulating layer 173 have openings that reach the conductive layer 172, and a plug 176 is provided to fill the opening.

[0208] In the pixel section 177, the light-emitting device 130 is provided on the insulating layer 175 and the plug 176. A protective layer 131 is provided to cover the light-emitting device 130. The substrate 120 is bonded to the protective layer 131 by a resin layer 122. Preferably, an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are provided between adjacent light-emitting devices 130.

[0209] 3B shows multiple cross sections of the inorganic insulating layer 125 and the insulating layer 127, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are connected to one another when the display device 100 is viewed from above. That is, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are insulating layers having openings above the first electrodes.

[0210] 3(B) shows light emitting device 130R, light emitting device 130G, and light emitting device 130B. Light emitting device 130R, light emitting device 130G, and light emitting device 130B emit light of different colors. For example, light emitting device 130R can emit red light, light emitting device 130G can emit green light, and light emitting device 130B can emit blue light. Furthermore, light emitting device 130R, light emitting device 130G, or light emitting device 130B may emit other visible light or infrared light.

[0211] The display device of one embodiment of the present invention can be, for example, a top-emission type that emits light in the direction opposite to the substrate on which the light-emitting device is formed. Note that the display device of one embodiment of the present invention may also be a bottom-emission type.

[0212] Examples of the light-emitting material contained in the light-emitting device 130 include organic compounds or organometallic complexes such as fluorescent materials (fluorescent compounds), phosphorescent materials (phosphorescent compounds), and materials that exhibit thermally activated delayed fluorescence (thermally activated delayed fluorescence: TADF materials). Furthermore, the light-emitting material may also be an inorganic compound such as quantum dots.

[0213] The light-emitting device 130R has a configuration as shown in FIG. 1A. It includes a first electrode (pixel electrode) composed of a conductive layer 151R and a conductive layer 152R, an organic compound layer 103R on the first electrode, a common layer 104 on the organic compound layer 103R, and a second electrode (common electrode) 102 on the common layer. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the organic compound layer 103R during processing. When the common layer 104 is provided, it is preferably an electron injection layer. When the common layer 104 is provided, the stacked structure of the organic compound layer 103R and the common layer 104 corresponds to the organic compound layer 103 in the first embodiment.

[0214] The light-emitting device 130G has a configuration as shown in FIG. 1A. It includes a first electrode (pixel electrode) composed of a conductive layer 151G and a conductive layer 152G, an organic compound layer 103G on the first electrode, a common layer 104 on the organic compound layer 103G, and a second electrode (common electrode) 102 on the common layer 104. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the organic compound layer 103G during processing. When the common layer 104 is provided, it is preferably an electron injection layer. When the common layer 104 is provided, the stacked structure of the organic compound layer 103G and the common layer 104 corresponds to the organic compound layer 103 in Embodiment 1.

[0215] The light-emitting device 130B has a configuration as shown in FIG. 1A. It includes a first electrode (pixel electrode) including a conductive layer 151B and a conductive layer 152B, an organic compound layer 103B on the first electrode, a common layer 104 on the organic compound layer 103B, and a second electrode (common electrode) 102 on the common layer 104. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the organic compound layer 103B during processing. When the common layer 104 is provided, it is preferably an electron injection layer. When the common layer 104 is provided, the stacked structure of the organic compound layer 103B and the common layer 104 corresponds to the organic compound layer 103 in the first embodiment.

[0216] One of the pixel electrode and the common electrode of the light-emitting device functions as an anode and the other functions as a cathode. In the following description, unless otherwise specified, the pixel electrode functions as an anode and the common electrode functions as a cathode.

[0217] The organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are independent island-shaped layers for each subpixel or each emitting color. By providing the organic compound layer 103 in an island shape for each light-emitting device 130, leakage current between adjacent light-emitting devices 130 can be suppressed even in a high-resolution display device. This makes it possible to prevent crosstalk and realize a display device with extremely high contrast. In particular, a display device with high current efficiency at low brightness can be realized.

[0218] The island-shaped organic compound layer 103 is formed by depositing an EL film and processing the EL film using a lithography method.

[0219] In the display device of one embodiment of the present invention, the first electrode (pixel electrode) of the light-emitting device preferably has a stacked structure. For example, in the example shown in FIG. 3B, the first electrode of the light-emitting device 130 has a stacked structure of a conductive layer 151 and a conductive layer 152. For example, when the display device 100 is a top-emission type and the pixel electrode of the light-emitting device 130 functions as an anode, the conductive layer 151 preferably has high reflectivity for visible light, and the conductive layer 152 preferably has transparency to visible light and a high work function. When the display device 100 is a top-emission type, the higher the reflectivity of the pixel electrode for visible light, the higher the extraction efficiency of light emitted from the organic compound layer 103. When the pixel electrode functions as an anode, the higher the work function of the pixel electrode, the easier it is to inject holes into the organic compound layer 103. As described above, by forming the pixel electrode of the light-emitting device 130 into a laminated structure of the conductive layer 151 having a high reflectivity for visible light and the conductive layer 152 having a high work function, the light-emitting device 130 can be made into a light-emitting device with high light extraction efficiency and low driving voltage.

[0220] When the conductive layer 151 is a layer having high reflectivity to visible light, the reflectivity of the conductive layer 151 to visible light is, for example, preferably 40% to 100%, more preferably 70% to 100%. When the conductive layer 152 is an electrode having transparency to visible light, the transmittance to visible light is preferably, for example, 40% or more.

[0221] Here, when the pixel electrode has a laminated structure made up of multiple layers, the pixel electrode may be altered due to, for example, a reaction between the multiple layers. For example, when a film formed after forming the pixel electrode is removed by a wet etching method, galvanic corrosion may occur when a chemical solution comes into contact with the pixel electrode.

[0222] Therefore, in the display device 100 of this embodiment, an insulating layer 156 is formed on the side surfaces of the conductive layer 151 and the conductive layer 152. This prevents a chemical solution from coming into contact with the conductive layer 151, even when a film formed after forming a pixel electrode having the conductive layer 151 and the conductive layer 152 is removed by wet etching, for example. This prevents, for example, galvanic corrosion from occurring in the pixel electrode. Therefore, the display device 100 can be manufactured by a method with a high yield, and can be a low-cost display device. Furthermore, since defects in the display device 100 can be prevented, the display device 100 can be a highly reliable display device.

[0223] For example, a metal material can be used for the conductive layer 151. Specifically, metals such as aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), neodymium (Nd), etc., and alloys containing appropriate combinations of these metals can also be used.

[0224] The conductive layer 152 can be formed using an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. For example, it is preferable to use a conductive oxide containing one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, and indium zinc oxide containing silicon. In particular, indium tin oxide containing silicon has a large work function, for example, a work function of 4.0 eV or more, and therefore can be suitably used for the conductive layer 152.

[0225] The conductive layer 151 may have a stacked structure of multiple layers containing different materials, and the conductive layer 152 may have a stacked structure of multiple layers containing different materials. In this case, the conductive layer 151 may include a layer containing a material that can be used for the conductive layer 152, such as a conductive oxide, or the conductive layer 152 may include a layer containing a material that can be used for the conductive layer 151, such as a metal material. For example, when the conductive layer 151 has a stacked structure of two or more layers, a layer in contact with the conductive layer 152 can be a layer containing a material that can be used for the conductive layer 152.

[0226] The insulating layer 156 may have a tapered end portion. Specifically, when the insulating layer 156 has a tapered end portion with a taper angle of less than 90°, coverage of structures provided along the side surfaces of the insulating layer 156 can be improved.

[0227] (Embodiment 3) In this embodiment, a light-emitting device of one embodiment of the present invention will be described with reference to FIGS. 4A to 4G and 5A to 5I.

[0228] [Pixel layout] In this embodiment, pixel layouts different from that shown in Fig. 3(A) will be mainly described. There are no particular limitations on the arrangement of sub-pixels, and various methods can be applied. Examples of sub-pixel arrangements include a stripe arrangement, an S-stripe arrangement, a matrix arrangement, a delta arrangement, a Bayer arrangement, and a pentile arrangement.

[0229] The top shape of the sub-pixels shown in the drawings in this embodiment mode corresponds to the top shape of the light-emitting region.

[0230] The top surface shape of the subpixel may be, for example, a triangle, a quadrangle (including a rectangle and a square), a polygon such as a pentagon, a polygon with rounded corners, an ellipse, or a circle.

[0231] Furthermore, the layout of the circuits constituting the sub-pixels is not limited to the range of the sub-pixels shown in the drawings, and may be arranged outside of the range.

[0232] An S-stripe arrangement is applied to the pixel 178 shown in Fig. 4(A). The pixel 178 shown in Fig. 4(A) is composed of three subpixels: a subpixel 110R, a subpixel 110G, and a subpixel 110B.

[0233] The pixel 178 shown in FIG. 4B includes a subpixel 110R having a generally trapezoidal or triangular top surface shape with rounded corners, a subpixel 110G having a generally trapezoidal or triangular top surface shape with rounded corners, and a subpixel 110B having a generally rectangular or hexagonal top surface shape with rounded corners. The subpixel 110R has a larger light-emitting area than the subpixel 110G. Thus, the shape and size of each subpixel can be determined independently. For example, the more reliable the light-emitting device, the smaller the size of the subpixel.

[0234] The Pentile arrangement is applied to the pixels 124a and 124b shown in Fig. 4(C). Fig. 4(C) shows an example in which the pixel 124a having the subpixel 110R and the subpixel 110G and the pixel 124b having the subpixel 110G and the subpixel 110B are arranged alternately.

[0235] Pixels 124a and 124b shown in Figures 4(D) to 4(F) are arranged in a delta configuration. Pixel 124a has two subpixels (subpixel 110R and subpixel 110G) in the top row (first row) and one subpixel (subpixel 110B) in the bottom row (second row). Pixel 124b has one subpixel (subpixel 110B) in the top row (first row) and two subpixels (subpixel 110R and subpixel 110G) in the bottom row (second row).

[0236] Figure 4(D) is an example in which each sub-pixel has an approximately rectangular top surface shape with rounded corners, Figure 4(E) is an example in which each sub-pixel has a circular top surface shape, and Figure 4(F) is an example in which each sub-pixel has an approximately hexagonal top surface shape with rounded corners.

[0237] In FIG. 4(F), each subpixel is arranged inside a densely arranged hexagonal region. Each subpixel is arranged so that it is surrounded by six other subpixels when focusing on a single subpixel. Furthermore, subpixels that emit light of the same color are arranged so that they are not adjacent to each other. For example, when focusing on subpixel 110R, three subpixels 110G and three subpixels 110B are arranged alternately to surround it.

[0238] 4G shows an example in which subpixels of each color are arranged in a zigzag pattern. Specifically, when viewed from above, the positions of the upper sides of two subpixels aligned in the row direction (for example, subpixels 110R and 110G, or subpixels 110G and 110B) are misaligned.

[0239] 4(A) to 4(G), it is preferable that the subpixel 110R is the subpixel R that emits red light, the subpixel 110G is the subpixel G that emits green light, and the subpixel 110B is the subpixel B that emits blue light. Note that the configuration of the subpixels is not limited to this, and the colors that the subpixels emit and their arrangement order can be determined appropriately. For example, the subpixel 110G may be the subpixel R that emits red light, and the subpixel 110R may be the subpixel G that emits green light.

[0240] In photolithography, the finer the pattern to be processed, the more significant the effect of light diffraction becomes. This impairs the fidelity of the photomask pattern when it is transferred by exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, a pattern with rounded corners is likely to be formed. As a result, the top surface shape of the subpixel may become a polygon with rounded corners, an ellipse, a circle, or the like.

[0241] Furthermore, in a method for manufacturing a light-emitting device according to one embodiment of the present invention, an organic compound layer is processed into an island shape using a resist mask. The resist film formed on the organic compound layer needs to be cured at a temperature lower than the heat resistance temperature of the organic compound layer. Therefore, depending on the heat resistance temperature of the material for the organic compound layer and the curing temperature of the resist material, the resist film may not be cured sufficiently. A resist film that is not cured sufficiently may have a shape that is different from the desired shape during processing. As a result, the top surface shape of the organic compound layer may be a polygon with rounded corners, an ellipse, a circle, or the like. For example, when a resist mask with a square top surface shape is formed, a resist mask with a circular top surface shape may be formed, resulting in a circular top surface shape of the organic compound layer.

[0242] In order to form the top surface of the organic compound layer into a desired shape, a technique for correcting the mask pattern in advance (OPC (Optical Proximity Correction) technique) may be used so that the design pattern and the transfer pattern coincide with each other. Specifically, in the OPC technique, a correction pattern is added to, for example, the corners of the figure on the mask pattern.

[0243] As shown in FIGS. 5A to 5I, a pixel can have four types of subpixels.

[0244] The pixels 178 shown in FIGS. 5(A) to 5(C) are arranged in a stripe pattern.

[0245] Figure 5(A) is an example in which each subpixel has a rectangular top surface shape, Figure 5(B) is an example in which each subpixel has a top surface shape that is a combination of two semicircles and a rectangle, and Figure 5(C) is an example in which each subpixel has an elliptical top surface shape.

[0246] The pixels 178 shown in FIGS. 5(D) to 5(F) are arranged in a matrix.

[0247] Figure 5(D) is an example in which each sub-pixel has a square top surface shape, Figure 5(E) is an example in which each sub-pixel has an approximately square top surface shape with rounded corners, and Figure 5(F) is an example in which each sub-pixel has a circular top surface shape.

[0248] 5(G) and 5(H) show an example in which one pixel 178 is configured in two rows and three columns.

[0249] 5(G) has three subpixels (subpixel 110R, subpixel 110G, and subpixel 110B) in the top row (first row) and one subpixel (subpixel 110W) in the bottom row (second row). In other words, pixel 178 has subpixel 110R in the left column (first column), subpixel 110G in the center column (second column), subpixel 110B in the right column (third column), and subpixel 110W across these three columns.

[0250] The pixel 178 shown in FIG. 5(H) has three subpixels (subpixels 110R, 110G, and 110B) in the top row (first row) and three subpixels 110W in the bottom row (second row). In other words, the pixel 178 has subpixels 110R and 110W in the left column (first column), subpixels 110G and 110W in the center column (second column), and subpixels 110B and 110W in the right column (third column). By aligning the subpixels in the top and bottom rows as shown in FIG. 5(H), it becomes possible to efficiently remove dust that may occur during the manufacturing process. Therefore, a light-emitting device with high display quality can be provided.

[0251] In the pixel 178 shown in FIGS. 5(G) and 5(H), the subpixels 110R, 110G, and 110B are laid out in a stripe arrangement, which can improve the display quality.

[0252] FIG. 5(I) shows an example in which one pixel 178 is configured in three rows and two columns.

[0253] 5(I) has subpixel 110R in the top row (first row), subpixel 110G in the middle row (second row), subpixel 110B across the first and second rows, and one subpixel (subpixel 110W) in the bottom row (third row). In other words, pixel 178 has subpixel 110R and subpixel 110G in the left column (first column), subpixel 110B in the right column (second column), and subpixel 110W across these two columns.

[0254] In the pixel 178 shown in FIG. 5(I), the layout of the subpixels 110R, 110G, and 110B is a so-called S-stripe arrangement, which can improve the display quality.

[0255] 5A to 5I includes four subpixels: subpixel 110R, subpixel 110G, subpixel 110B, and subpixel 110W. For example, the subpixel 110R may emit red light, the subpixel 110G may emit green light, the subpixel 110B may emit blue light, and the subpixel 110W may emit white light. Note that at least one of the subpixels 110R, 110G, 110B, and 110W may emit cyan light, magenta light, yellow light, or near-infrared light.

[0256] As described above, in the light-emitting device of one embodiment of the present invention, various layouts can be applied to pixels each including a subpixel having a light-emitting device.

[0257] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when multiple configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0258] (Fourth embodiment) In this embodiment, a display device according to one embodiment of the present invention will be described.

[0259] The display device of the present embodiment can be a high-definition display device, and can therefore be used as a display unit for information terminals (wearable devices) such as wristwatches and bracelets, as well as for wearable devices that can be worn on the head, such as VR devices such as head-mounted displays (HMDs) and AR devices such as glasses.

[0260] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices with relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as in the display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound reproduction devices.

[0261] [Display module] 6(A) shows a perspective view of the display module 280. The display module 280 has a display device 100A and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100A, and may be any of the display devices 100B, 100C, 100D, 100D2, 100E, and 100E2 described below.

[0262] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display unit 281. The display unit 281 is an area that displays an image in the display module 280, and is an area where light from each pixel provided in a pixel unit 284 (described later) can be viewed.

[0263] 6(B) is a perspective view schematically showing the configuration on the substrate 291 side. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked on the substrate 291. A terminal portion 285 for connecting to an FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 composed of a plurality of wirings.

[0264] The pixel section 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of Fig. 6(B). The various configurations described in the previous embodiments can be applied to the pixel 284a.

[0265] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0266] One pixel circuit 283a is a circuit that controls the driving of a plurality of devices included in one pixel 284a.

[0267] The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, it is preferable that the circuit portion 282 includes one or both of a gate line driver circuit and a source line driver circuit. In addition, the circuit portion 282 may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, etc.

[0268] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may be mounted on the FPC 290.

[0269] The display module 280 can be configured such that one or both of the pixel circuit unit 283 and the circuit unit 282 are stacked below the pixel unit 284, thereby making it possible to extremely increase the aperture ratio (effective display area ratio) of the display unit 281.

[0270] Such a display module 280 has extremely high resolution and can therefore be suitably used in VR devices such as HMDs or glasses-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so that even if the display unit is enlarged with the lenses, the pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this and can be suitably used in electronic devices having relatively small display units.

[0271] [Display device 100A] The display device 100A shown in FIG. 7A includes a substrate 301, a light emitting device 130R, a light emitting device 130G, a light emitting device 130B, a capacitor 240, and a transistor 310. The display device 100A shown in FIG.

[0272] The substrate 301 corresponds to the substrate 291 in FIGS. 6A and 6B. The transistor 310 is a transistor having a channel formation region in the substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region in which the substrate 301 is doped with impurities and functions as a source or drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311.

[0273] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0274] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided on the insulating layer 261 .

[0275] Capacitor 240 has conductive layer 241, conductive layer 245, and insulating layer 243 located therebetween. Conductive layer 241 functions as one electrode of capacitor 240, conductive layer 245 functions as the other electrode of capacitor 240, and insulating layer 243 functions as a dielectric of capacitor 240.

[0276] The conductive layer 241 is provided over the insulating layer 261 and is buried in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 by a plug 271 buried in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0277] An insulating layer 255 is provided covering the capacitor 240, an insulating layer 174 is provided on the insulating layer 255, and an insulating layer 175 is provided on the insulating layer 174. Light-emitting device 130R, light-emitting device 130G, and light-emitting device 130B are provided on the insulating layer 175. An insulator is provided in the region between adjacent light-emitting devices.

[0278] An insulating layer 156R is provided to have a region overlapping with a side surface of the conductive layer 151R, an insulating layer 156G is provided to have a region overlapping with a side surface of the conductive layer 151G, and an insulating layer 156B is provided to have a region overlapping with a side surface of the conductive layer 151B. Further, a conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R, a conductive layer 152G is provided to cover the conductive layer 151G and the insulating layer 156G, and a conductive layer 152B is provided to cover the conductive layer 151B and the insulating layer 156B. A sacrificial layer 158R is located on the organic compound layer 103R, a sacrificial layer 158G is located on the organic compound layer 103G, and a sacrificial layer 158B is located on the organic compound layer 103B.

[0279] The conductive layer 151R, the conductive layer 151G, and the conductive layer 151B are electrically connected to one of the source and drain of the transistor 310 via an insulating layer 243, an insulating layer 255, an insulating layer 174, a plug 256 embedded in the insulating layer 175, a conductive layer 241 embedded in the insulating layer 254, and a plug 271 embedded in the insulating layer 261. Various conductive materials can be used for the plug.

[0280] Furthermore, a protective layer 131 is provided on the light-emitting devices 130R, 130G, and 130B. A substrate 120 is bonded to the protective layer 131 with a resin layer 122. For details of the components from the light-emitting devices 130 to the substrate 120, refer to embodiment 3. The substrate 120 corresponds to the substrate 292 in FIG. 6(A).

[0281] Fig. 7(B) is a modified example of the display device 100A shown in Fig. 7(A). The display device shown in Fig. 7(B) has a colored layer 132R, a colored layer 132G, and a colored layer 132B, and the light-emitting device 130 has an area where it overlaps with one of the colored layers 132R, 132G, and 132B. In the display device shown in Fig. 7(B), the light-emitting device 130 can emit, for example, white light. Furthermore, for example, the colored layer 132R can transmit red light, the colored layer 132G can transmit green light, and the colored layer 132B can transmit blue light.

[0282] [Display device 100B] FIG. 8 shows a perspective view of the display device 100B, and FIG. 9 shows a cross-sectional view of the display device 100C.

[0283] The display device 100B has a configuration in which a substrate 352 and a substrate 351 are bonded together. In Fig. 8, the substrate 352 is indicated by a dashed line.

[0284] The display device 100B has a pixel unit 177, a connection unit 140, a circuit 356, wiring 355, etc. FIG. 8 shows an example in which an IC 354 and an FPC 353 are mounted on the display device 100B. Therefore, the configuration shown in FIG. 8 can also be called a display module having the display device 100B, an IC (integrated circuit), and an FPC. Here, a display device with a connector such as an FPC attached to a substrate, or a display device with an IC mounted on the substrate, is called a display module.

[0285] The connection section 140 is provided outside the pixel section 177. There may be one or more connection sections 140. The connection section 140 electrically connects the common electrode of the light-emitting device and the conductive layer, and can supply a potential to the common electrode.

[0286] The circuit 356 can be, for example, a scanning line driver circuit.

[0287] The wiring 355 has a function of supplying signals and power to the pixel portion 177 and the circuit 356. The signals and power are input to the wiring 355 from the outside via the FPC 353 or from the IC 354.

[0288] 8 shows an example in which an IC 354 is provided on a substrate 351 by a COG (Chip On Glass) method or a COF (Chip on Film) method. The IC 354 may be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. The display device 100B and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by, for example, a COF method.

[0289] Figure 9 shows an example of a cross section of the display device 100B in Figure 8, where part of the area including the FPC 353, part of the circuit 356, part of the pixel section 177, part of the connection section 140, and part of the area including the end portion are cut away, as display device 100C.

[0290] [Display device 100C] The display device 100C shown in Figure 9 has, between substrate 351 and substrate 352, transistor 201, transistor 205, light-emitting device 130R that emits red light, light-emitting device 130G that emits green light, and light-emitting device 130B that emits blue light, etc.

[0291] For details of the light emitting devices 130R, 130G, and 130B, refer to the third embodiment.

[0292] Light-emitting device 130R has conductive layer 224R, conductive layer 151R on conductive layer 224R, and conductive layer 152R on conductive layer 151R. Light-emitting device 130G has conductive layer 224G, conductive layer 151G on conductive layer 224G, and conductive layer 152G on conductive layer 151G. Light-emitting device 130B has conductive layer 224B, conductive layer 151B on conductive layer 224B, and conductive layer 152B on conductive layer 151B.

[0293] The conductive layer 224R is connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214. An end of the conductive layer 151R is located outside an end of the conductive layer 224R. An insulating layer 156R is provided to have a region in contact with a side surface of the conductive layer 151R, and a conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R.

[0294] Conductive layer 224G, conductive layer 151G, conductive layer 152G, and insulating layer 156G in light-emitting device 130G, and conductive layer 224B, conductive layer 151B, conductive layer 152B, and insulating layer 156B in light-emitting device 130B are similar to conductive layer 224R, conductive layer 151R, conductive layer 152R, and insulating layer 156R in light-emitting device 130R, and therefore detailed description thereof will be omitted.

[0295] Recesses are formed in conductive layers 224R, 224G, and 224B so as to cover the openings provided in insulating layer 214. Layer 128 is buried in the recesses.

[0296] Layer 128 has the function of filling in recesses in conductive layer 224R, conductive layer 224G, and conductive layer 224B and flattening the surface. Conductive layers 151R, 151G, and 151B, which are electrically connected to conductive layer 224R, conductive layer 224G, and conductive layer 224B, are provided on conductive layer 224R, conductive layer 224G, and conductive layer 224B and layer 128. Therefore, the regions overlapping with the recesses in conductive layer 224R, conductive layer 224G, and conductive layer 224B can also be used as light-emitting regions, thereby increasing the aperture ratio of the pixel.

[0297] The layer 128 may be an insulating layer or a conductive layer. Various inorganic insulating materials, organic insulating materials, and conductive materials can be used for the layer 128 as appropriate. In particular, the layer 128 is preferably formed using an insulating material, and is particularly preferably formed using an organic insulating material. For example, the organic insulating materials that can be used for the insulating layer 127 described above can be used for the layer 128.

[0298] A protective layer 131 is provided on the light-emitting devices 130R, 130G, and 130B. The protective layer 131 and the substrate 352 are bonded via an adhesive layer 142. A light-shielding layer 157 is provided on the substrate 352. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting device 130. In FIG. 9, the space between the substrates 352 and 351 is filled with the adhesive layer 142, and a solid sealing structure is applied. Alternatively, the space may be filled with an inert gas (nitrogen, argon, etc.), and a hollow sealing structure may be applied. In this case, the adhesive layer 142 may be provided so as not to overlap with the light-emitting devices. Alternatively, the space may be filled with a resin different from the frame-shaped adhesive layer 142.

[0299] 9 shows an example in which connecting portion 140 has conductive layer 224C obtained by processing the same conductive film as conductive layers 224R, 224G, and 224B, conductive layer 151C obtained by processing the same conductive film as conductive layers 151R, 151G, and 151B, and conductive layer 152C obtained by processing the same conductive film as conductive layers 152R, 152G, and 152B. Also shown in FIG. 9 is an example in which insulating layer 156C is provided so as to have a region overlapping with a side surface of conductive layer 151C.

[0300] The display device 100C is a top-emission type. Light emitted by the light-emitting device is emitted toward the substrate 352. The substrate 352 is preferably made of a material that is highly transparent to visible light. The pixel electrodes contain a material that reflects visible light, and the counter electrode (common electrode 155) contains a material that transmits visible light.

[0301] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided in this order over the substrate 351. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0302] The insulating layers 211, 213, and 215 are each preferably made of an inorganic insulating film.

[0303] The insulating layer 214, which functions as a planarizing layer, is preferably an organic insulating layer.

[0304] The transistor 201 and the transistor 205 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a conductive layer 222a and a conductive layer 222b functioning as a source and a drain, a semiconductor layer 231, an insulating layer 213 functioning as a gate insulating layer, and a conductive layer 223 functioning as a gate.

[0305] A connection portion 204 is provided in a region of the substrate 351 where the substrate 352 does not overlap. In the connection portion 204, the source electrode or drain electrode of the transistor 201 is electrically connected to the FPC 353 via a conductive layer 166 and a connection layer 242. The conductive layer 166 has an example of a laminated structure including a conductive film obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive film obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive film obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. The conductive layer 166 is exposed on the top surface of the connection portion 204. This allows the connection portion 204 and the FPC 353 to be electrically connected via the connection layer 242.

[0306] It is preferable to provide a light-shielding layer 157 on the surface of substrate 352 facing substrate 351. Light-shielding layer 157 can be provided between adjacent light-emitting devices, on connecting portions 140, on circuits 356, etc. Various optical members can be arranged on the outside of substrate 352.

[0307] The materials that can be used for the substrate 120 can be used for the substrate 351 and the substrate 352, respectively.

[0308] The adhesive layer 142 can be made of a material that can be used for the resin layer 122 .

[0309] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0310] [Display device 100D] The display device 100D shown in FIG. 10 differs from the display device 100C shown in FIG. 9 mainly in that it is a bottom-emission display device.

[0311] Light emitted from the light emitting device is emitted toward the substrate 351. It is preferable that a material with high transparency to visible light is used for the substrate 351. On the other hand, the light transparency of the material used for the substrate 352 is not an issue.

[0312] A light-shielding layer 317 is preferably formed between the substrate 351 and the transistor 201 and between the substrate 351 and the transistor 205. Figure 10 shows an example in which the light-shielding layer 317 is provided over the substrate 351, the insulating layer 153 is provided over the light-shielding layer 317, and the transistors 201, 205, etc. are provided over the insulating layer 153.

[0313] Light emitting device 130R includes conductive layer 112R, conductive layer 126R on conductive layer 112R, and conductive layer 129R on conductive layer 126R.

[0314] Light emitting device 130B includes conductive layer 112B, conductive layer 126B on conductive layer 112B, and conductive layer 129B on conductive layer 126B.

[0315] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B are each made of a material that is highly transparent to visible light. The second electrode 102 is preferably made of a material that reflects visible light.

[0316] Although the light emitting device 130G is not shown in FIG. 10, the light emitting device 130G is also provided.

[0317] In addition, although FIG. 10 and other figures show an example in which the top surface of the layer 128 has a flat portion, the shape of the layer 128 is not particularly limited.

[0318] [Display device 100D2] The display device 100D2 shown in Fig. 11(A) is an example of a bottom-emission type display device that differs from the display device 100D shown in Fig. 10. The display device 100D2 differs from the display device 100D in that it has an organic resin layer 180. Note that in the drawing, the reference numerals of the same components as those in Fig. 10 may be omitted, and the description in Fig. 10 can be referred to for details.

[0319] 11(B) shows a top view layout of pixel 178 (pixel 178a and pixel 178b) having subpixels 110 (subpixels 110R, 110G, 110B, and 110W), and FIG. 11(C) shows a top view of organic resin layer 180 in a region where subpixels 110R and 110W of pixel 178 are formed. The width between light-shielding layers 317 is width 110Rw in the light-emitting region of subpixel 110R.

[0320] As shown in FIG. 11(A), the organic resin layer 180 is provided on the insulating layer 214. As shown in the region surrounded by the dashed line in FIG. 11(A) and in FIG. 11(C), the organic resin layer 180 has curved recesses 181 (recesses 181a and 181b) at least in the region where the subpixels are formed. Note that the recesses 181 may also be provided outside the light-emitting region, such as recess 181c. Providing recess 181c refracts light emitted in the region overlapping with the light-shielding layer 317 or light traveling to the region overlapping with the light-shielding layer 317, allowing it to be extracted from the light-emitting region, thereby improving light-emitting efficiency.

[0321] A plurality of recesses 181 may be formed in a matrix. Recesses 181a and 181b may be provided in contact with each other, or may have a flat surface between them.

[0322] 11, the recess has a hexagonal top surface shape (FIG. 11(C)) and a semicircular cross-sectional shape (FIG. 11(A)), but other shapes may be used as needed. For example, the recess may have a polygonal top surface shape such as a triangle, a quadrangle (including a rectangle and a square), a pentagon, or any other polygon with rounded corners, an ellipse, or a circle.

[0323] An insulating layer containing an organic material can be used as the organic resin layer 180. For example, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenol resin, precursors of these resins, etc. can be used as the organic resin layer 180. Alternatively, 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 as the organic resin layer 180.

[0324] Furthermore, a photosensitive resin can be used as the organic resin layer 180. A photoresist can be used as the photosensitive resin. The photosensitive resin can be a positive type material or a negative type material.

[0325] The organic resin layer 180 may contain a material that absorbs visible light. For example, the organic resin layer 180 itself may be made of a material that absorbs visible light, or the organic resin layer 180 may contain a pigment that absorbs visible light. For example, the organic resin layer 180 may be made of a resin that can be used as a color filter that transmits red, blue, or green light and absorbs other light, or a resin that contains carbon black as a pigment and functions as a black matrix.

[0326] In addition, a first electrode 101 (a first electrode 101R and a first electrode 101W) is provided on the organic resin layer 180, and an organic compound layer 103 is provided on the first electrode 101. Ends of the first electrode 101 and the organic compound layer 103 may be covered with an insulating layer 127.

[0327] Furthermore, the first electrode 101 formed on the organic resin layer 180 has a recess similar to the recess of the organic resin layer 180. Furthermore, the organic compound layer 103 formed on the first electrode 101 has a recess similar to the recess of the first electrode 101. Furthermore, the common layer 104 formed on the organic compound layer 103 has a recess similar to the recess of the organic compound layer 103. Furthermore, the second electrode 102 formed on the common layer 104 has a recess similar to the recess of the common layer 104. That is, the recesses of the organic resin layer 180, the first electrode 101, the organic compound layer 103, the common layer 104, and the second electrode 102 have a structure in which they overlap one another.

[0328] In addition, a common layer 104 is provided over the organic compound layer 103 and the insulating layer 127, and a second electrode 102 is provided over the common layer 104. A protective layer 131 is provided over the second electrode 102, and the second electrode 102 is bonded to a substrate 352 via an adhesive layer 142.

[0329] Although light emitting device 130G and light emitting device 130B are not shown in FIG. 11, light emitting device 130G and light emitting device 130B are also provided.

[0330] [Display device 100E] The display device 100E shown in FIG. 12 is a modification of the display device 100C shown in FIG. 9, and differs from the display device 100C mainly in that it has colored layers 132R, 132G, and 132B.

[0331] In the display device 100E, the light-emitting device 130 has an area that overlaps one of the colored layer 132R, the colored layer 132G, and the colored layer 132B. The colored layer 132R, the colored layer 132G, and the colored layer 132B can be provided on the surface of the substrate 352 facing the substrate 351. An end of the colored layer 132R, an end of the colored layer 132G, and an end of the colored layer 132B can overlap the light-shielding layer 157.

[0332] In the display device 100E, the light-emitting device 130 can emit, for example, white light. Furthermore, for example, the colored layer 132R can transmit red light, the colored layer 132G can transmit green light, and the colored layer 132B can transmit blue light. The display device 100E may be configured such that the colored layers 132R, 132G, and 132B are provided between the protective layer 131 and the adhesive layer 142.

[0333] [Display device 100E2] The display device 100E2 shown in Fig. 13(A) is a modified example of the display device 100E shown in Fig. 12, and has microlenses 182 on the colored layers 132R, 132G, and 132B. Note that in the figure, the reference numerals of the same components as those in Fig. 12 may be omitted, and the description in Fig. 12 can be referred to for details.

[0334] 13(B) shows a top view layout of a pixel 178 (pixels 178a and 178b) having subpixels 110 (subpixels 110R, 110G, and 110B), and Fig. 13(C) shows a top view of a microlens 182 in a region where the subpixels 110R, 110G, and 110B of the pixel 178 are formed. Note that the region where the common electrode 155 and the organic compound layer 103 are in contact has a width 110Gw in the light-emitting region of the subpixel 110G.

[0335] 13(A) has a planarization film 143 provided on a protective layer 131, and colored layers 132R, 132G, and 132B provided on the planarization film 143. A planarization film 144 is provided so as to cover the colored layers 132R, 132G, and 132B. A microlens 182 is provided on the planarization film 144.

[0336] As shown in FIG. 13C, the microlens 182 may be provided for each sub-pixel in a region where the sub-pixel is formed.

[0337] 13(C), the top surface shape of the microlens 182 is shown as a hexagon, but other shapes may be used as needed. For example, the top surface shape of the microlens 182 may be a polygon such as a triangle, a quadrangle (including a rectangle and a square), a pentagon, or any other polygon with rounded corners, an ellipse, or a circle.

[0338] The microlenses 182 can be formed using the same material as the organic resin layer 180 .

[0339] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when multiple configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0340] (Embodiment 5) In this embodiment, an electronic device according to one embodiment of the present invention will be described.

[0341] The electronic devices of this embodiment include the light-emitting device of one embodiment of the present invention in their display portions. The light-emitting device of one embodiment of the present invention is highly reliable and can easily achieve high definition and high resolution. Therefore, the light-emitting device can be used in the display portions of various electronic devices.

[0342] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound playback devices.

[0343] In particular, the light-emitting device of one embodiment of the present invention can have high resolution and can therefore be suitably used in electronic devices having a relatively small display portion. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), and head-mounted wearable devices such as VR devices such as head-mounted displays, AR glasses-type devices, and MR (Mixed Reality) devices.

[0344] The light-emitting device of one embodiment of the present invention preferably has an extremely high resolution such as HD (1280 × 720 pixels), FHD (1920 × 1080 pixels), WQHD (2560 × 1440 pixels), WQXGA (2560 × 1600 pixels), 4K (3840 × 2160 pixels), or 8K (7680 × 4320 pixels). A resolution of 4K, 8K, or higher is particularly preferable. Furthermore, the pixel density (resolution) of the light-emitting device of one embodiment of the present invention is preferably 100 ppi or higher, more preferably 300 ppi or higher, more preferably 500 ppi or higher, more preferably 1000 ppi or higher, more preferably 2000 ppi or higher, more preferably 3000 ppi or higher, more preferably 5000 ppi or higher, and even more preferably 7000 ppi or higher. By using a light-emitting device having either or both of high resolution and high definition, it is possible to further enhance the sense of realism and depth. Furthermore, the screen ratio (aspect ratio) of the light-emitting device according to one embodiment of the present invention is not particularly limited. For example, the light-emitting device can accommodate various screen ratios such as 1:1 (square), 4:3, 16:9, and 16:10.

[0345] The electronic device of this embodiment may have a sensor (including a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0346] The electronic device of the present embodiment can have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to execute various software (programs), a wireless communication function, a function to read out programs or data recorded on a recording medium, etc.

[0347] 14(A) to 14(D), an example of a wearable device that can be worn on the head will be described. These wearable devices have at least one of the following functions: a function to display AR content, a function to display VR content, a function to display SR (Substitutional Reality) content, and a function to display MR content. By having an electronic device have the function to display at least one of AR, VR, SR, and MR content, it is possible to enhance the sense of immersion for the user.

[0348] The electronic device 700A shown in FIG. 14(A) and the electronic device 700B shown in FIG. 14(B) each have a pair of display panels 751, a pair of housings 721, a communication unit (not shown), a pair of mounting units 723, a control unit (not shown), an imaging unit (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

[0349] The light-emitting device of one embodiment of the present invention can be applied to the display panel 751. Therefore, the electronic device can be highly reliable.

[0350] Electronic device 700A and electronic device 700B can each project an image displayed on display panel 751 onto display area 756 of optical member 753. Because optical member 753 is translucent, the user can see the image displayed in the display area superimposed on a transmitted image visually recognized through optical member 753. Therefore, electronic device 700A and electronic device 700B are each electronic devices capable of AR display.

[0351] Electronic device 700A and electronic device 700B may be provided with a camera capable of capturing an image in front of them as an imaging unit. Furthermore, electronic device 700A and electronic device 700B may each be provided with an acceleration sensor such as a gyro sensor, thereby detecting the orientation of the user's head and displaying an image corresponding to that orientation in display area 756.

[0352] The communication unit has a wireless communication device, and can supply, for example, a video signal via the wireless communication device. Note that instead of or in addition to the wireless communication device, a connector to which a cable through which a video signal and a power supply potential can be connected may be provided.

[0353] Furthermore, the electronic device 700A and the electronic device 700B are provided with batteries, which can be charged wirelessly and / or by wire.

[0354] The housing 721 may be provided with a touch sensor module. The touch sensor module has a function of detecting a touch on the outer surface of the housing 721. The touch sensor module detects a tap operation, a slide operation, or the like by the user, and can execute various processes. For example, a tap operation can execute processes such as pausing or resuming a video, and a slide operation can execute processes such as fast-forwarding or fast-rewinding. Furthermore, providing a touch sensor module on each of the two housings 721 can broaden the range of operations.

[0355] Various touch sensors can be used as the touch sensor module. For example, various types of touch sensors can be used, such as a capacitance type, a resistive film type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, or an optical type. In particular, it is preferable to use a capacitance type or an optical type sensor in the touch sensor module.

[0356] When an optical touch sensor is used, a photoelectric conversion device (also called a photoelectric conversion element) can be used as the light receiving device. The active layer of the photoelectric conversion device can be made of either or both of an inorganic semiconductor and an organic semiconductor.

[0357] The electronic device 800A shown in Figure 14(C) and the electronic device 800B shown in Figure 14(D) each have a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0358] The light-emitting device of one embodiment of the present invention can be applied to the display portion 820. Therefore, the electronic device can be highly reliable.

[0359] Display unit 820 is provided inside housing 821 at a position that can be viewed through lens 832. Also, by displaying different images on the pair of display units 820, it is possible to perform a three-dimensional display using parallax.

[0360] Electronic device 800A and electronic device 800B can each be said to be electronic devices for VR. A user wearing electronic device 800A or electronic device 800B can view an image displayed on display unit 820 through lens 832.

[0361] It is preferable that electronic device 800A and electronic device 800B each have a mechanism that can adjust the left and right positions of lens 832 and display unit 820 so that they are optimally positioned according to the position of the user's eyes. It is also preferable that electronic device 800A and electronic device 800B each have a mechanism that can adjust the focus by changing the distance between lens 832 and display unit 820.

[0362] The user can wear the electronic device 800A or the electronic device 800B on the head by using the wearing unit 823. Note that, for example, in Fig. 14(C), the wearing unit 823 is shaped like the temples of glasses (also called temples, etc.), but is not limited to this. The wearing unit 823 may be shaped like a helmet or a band, for example, as long as it can be worn by the user.

[0363] The imaging unit 825 has a function of acquiring external information. Data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used for the imaging unit 825. Furthermore, multiple cameras may be provided to support multiple angles of view, such as telephoto and wide angle.

[0364] Although an example having the imaging unit 825 has been shown here, a distance measuring sensor (hereinafter also referred to as a detection unit) capable of measuring the distance to an object may be provided. That is, the imaging unit 825 is one aspect of the detection unit. As the detection unit, for example, an image sensor or a range image sensor such as a LIDAR (Light Detection and Ranging) can be used. By using an image obtained by the camera and an image obtained by the range image sensor, more information can be obtained, enabling more accurate gesture operations.

[0365] Electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone. For example, a configuration having such a vibration mechanism can be applied to one or more of display unit 820, housing 821, and wearing unit 823. This allows a user to enjoy video and audio simply by wearing electronic device 800A, without the need for separate audio equipment such as headphones, earphones, or speakers.

[0366] The electronic device 800A and the electronic device 800B may each have an input terminal to which a cable can be connected for supplying a video signal from a video output device or the like and power for charging a battery provided in the electronic device.

[0367] The electronic device of one embodiment of the present invention may have a function of wireless communication with an earphone 750. The earphone 750 has a communication unit (not shown) and has a wireless communication function. The earphone 750 can receive information (e.g., audio data) from the electronic device through the wireless communication function. For example, the electronic device 700A shown in FIG. 14A has a function of transmitting information to the earphone 750 through the wireless communication function. Furthermore, for example, the electronic device 800A shown in FIG. 14C has a function of transmitting information to the earphone 750 through the wireless communication function.

[0368] 14B includes an earphone unit 727. For example, the earphone unit 727 and the control unit may be connected to each other by wire. Part of the wiring connecting the earphone unit 727 and the control unit may be disposed inside the housing 721 or the wearing unit 723.

[0369] 14(D) includes an earphone unit 827. For example, the earphone unit 827 and the control unit 824 can be configured to be connected to each other by wire. A portion of the wiring connecting the earphone unit 827 and the control unit 824 may be disposed inside the housing 821 or the wearing unit 823. The earphone unit 827 and the wearing unit 823 may also have a magnet. This allows the earphone unit 827 to be fixed to the wearing unit 823 by magnetic force, which is preferable as it makes storage easier.

[0370] The electronic device may have an audio output terminal to which earphones or headphones can be connected. The electronic device may also have one or both of an audio input terminal and an audio input mechanism. For example, a sound collection device such as a microphone can be used as the audio input mechanism. By having the audio input mechanism, the electronic device may be endowed with the functionality of a so-called headset.

[0371] As described above, the electronic devices of one embodiment of the present invention are preferably either glasses-type devices (such as the electronic devices 700A and 700B) or goggle-type devices (such as the electronic devices 800A and 800B).

[0372] Furthermore, the electronic device according to one embodiment of the present invention can transmit information to the earphone via a wired or wireless connection.

[0373] An electronic device 6500 shown in FIG. 15A is a portable information terminal that can be used as a smartphone.

[0374] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508. The display portion 6502 has a touch panel function.

[0375] The light-emitting device of one embodiment of the present invention can be applied to the display portion 6502. Therefore, the electronic device can be highly reliable.

[0376] FIG. 15B is a schematic cross-sectional view including the end portion of the housing 6501 on the microphone 6506 side.

[0377] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0378] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0379] In an area outside the display unit 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0380] The light-emitting device of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. Furthermore, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. Furthermore, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0381] 15C shows an example of a television set. A television set 7100 includes a display portion 7000 built in a housing 7171. Here, the housing 7171 is supported by a stand 7173.

[0382] The light-emitting device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can have high reliability.

[0383] 15C can be operated using an operation switch provided on the housing 7171 and a separate remote control 7151. Alternatively, the display portion 7000 may be provided with a touch sensor, and the television set 7100 may be operated by touching the display portion 7000 with a finger or the like. The remote control 7151 may have a display portion that displays information output from the remote control 7151. Channels and volume can be controlled by operation keys or a touch panel provided on the remote control 7151, and an image displayed on the display portion 7000 can be controlled.

[0384] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. In addition, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0385] 15D shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214. The housing 7211 includes a display portion 7000.

[0386] The light-emitting device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can have high reliability.

[0387] 15(E) and 15(F) show an example of digital signage.

[0388] 15E includes a housing 7301, a display portion 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0389] 15F shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0390] 15E and 15F, the light-emitting device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can have high reliability.

[0391] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it will attract people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[0392] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000 but also allows the user to intuitively operate it. Furthermore, when used to provide information such as route information or traffic information, intuitive operation can improve usability.

[0393] 15(E) and 15(F), the digital signage 7300 or the digital signage 7400 is preferably capable of wirelessly linking with an information terminal 7311 or an information terminal 7411 such as a smartphone carried by a user. For example, advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or the information terminal 7411. By operating the information terminal 7311 or the information terminal 7411, the display on the display unit 7000 can be switched.

[0394] Furthermore, the digital signage 7300 or the digital signage 7400 can be made to run a game using the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller), thereby allowing an unspecified number of users to simultaneously participate in and enjoy the game.

[0395] The electronic devices shown in Figures 16(A) to 16(G) have a housing 9000, a display portion 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including a function to measure force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays), a microphone 9008, etc.

[0396] 16(A) to 16(G) have various functions. For example, they may have a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to control processing using various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. Note that the functions of the electronic devices are not limited to these, and they may have various other functions. The electronic devices may have multiple display units. Furthermore, the electronic devices may have a function to include a camera or the like to capture still images or videos and store them on a recording medium (external or built-in to the camera), a function to display the captured images on the display unit, etc.

[0397] The electronic devices shown in FIGS. 16A to 16G will be described in detail below.

[0398] FIG. 16A is a perspective view showing a mobile information terminal 9171. The mobile information terminal 9171 can be used as, for example, a smartphone. Note that the mobile information terminal 9171 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, or the like. The mobile information terminal 9171 can display text and image information on multiple surfaces thereof. FIG. 16A shows an example in which three icons 9050 are displayed. Information 9051 indicated by a dashed rectangle can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notification of an incoming email, SNS, phone call, etc., the title of the email or SNS, the sender's name, the date and time, the remaining battery level, and radio wave intensity. Alternatively, the icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0399] 16B is a perspective view showing a mobile information terminal 9172. The mobile information terminal 9172 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9172 while the mobile information terminal 9172 is placed in a breast pocket of clothes. The user can check the display without taking the mobile information terminal 9172 out of the pocket and decide, for example, whether to answer a call.

[0400] 16(C) is a perspective view of a tablet terminal 9173. The tablet terminal 9173 is capable of executing various applications such as mobile phone calls, e-mails, text browsing and creation, music playback, internet communication, and computer games, for example. The tablet terminal 9173 has a display portion 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front side of a housing 9000, operation keys 9005 as operation buttons on the left side of the housing 9000, and a connection terminal 9006 on the bottom.

[0401] 16D is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display portion 9001 is curved, and display can be performed along the curved display surface. The mobile information terminal 9200 can also perform hands-free conversation by communicating with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and reception with another information terminal and charge itself through a connection terminal 9006. Note that charging may be performed by wireless power supply.

[0402] 16(E) to 16(G) are perspective views showing a foldable mobile information terminal 9201. FIG. 16(E) shows the mobile information terminal 9201 in an unfolded state, FIG. 16(G) shows it in a folded state, and FIG. 16(F) is a perspective view showing a state in the process of changing from one of FIG. 16(E) and FIG. 16(G) to the other. The mobile information terminal 9201 is highly portable when folded, and has a seamless, wide display area when unfolded, providing excellent viewability of the display. A display portion 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display portion 9001 can be bent with a curvature radius of 0.1 mm to 150 mm.

[0403] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when multiple configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate. [Example]

[0404] In this example, light-emitting devices 1A to 1D according to one embodiment of the present invention were fabricated.

[0405] The structural formulas of the organic compounds used in light-emitting devices 1A to 1D are shown below.

[0406] [ka]

[0407] As shown in FIG. 17, each device has a structure in which a hole injection layer 811, a hole transport layer 812, a light-emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are sequentially stacked on a first electrode 801 formed on a glass substrate 800, and a second electrode 802 is stacked on the electron injection layer 815.

[0408] <Method for Fabricating Light-Emitting Device 1A> On a glass substrate 800, indium tin oxide containing silicon oxide (ITSO) was deposited by sputtering to a thickness of 110 nm to form a first electrode 801. The electrode area was 4 mm 2 (2mm x 2mm).

[0409] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water and baked at 200°C for 1 hour. -4 The substrate was placed in a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and vacuum-baked at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, followed by natural cooling for 45 minutes.

[0410] Next, the substrate on which the first electrode 801 was formed was fixed to a substrate holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 801 was formed faced downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited on the first electrode 801 to a thickness of 10 nm such that the weight ratio of PCBBiF:OCHD-003 was 1:0.03, thereby forming a hole injection layer 811.

[0411] Next, PCBBiF was deposited on the hole injection layer 811 by a deposition method using resistance heating to a film thickness of 90 nm, and then N,N-bis{4-[(dibenzofuran-1,2,3,6,7,8,9-d7)-4-yl]phenyl-2,3,5,6-d4}-p-terphenyl-2,2′,2″,3,3′,3″,4″,5,5′,5″,6,6′,6″-d 13 -4-amine (abbreviation: DBfBB1TP-d 35 ) was evaporated to a thickness of 10 nm to form a hole transport layer 812.

[0412] Next, on the hole-transporting layer 812, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene-1,2,3,4,5,6,7,8-d8 (abbreviation: αN-βNPAnth-d8) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of αN-βNPAnth-d8:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813. The HOMO level of αN-βNPAnth-d8 was −5.85 eV and the LUMO level was −2.73 eV, measured by the same method as described herein.

[0413] Next, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) was evaporated to a thickness of 10 nm on the light-emitting layer 813, and then 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) was evaporated to a thickness of 15 nm to form an electron-transporting layer 814. The HOMO level of mFBPTzn was −6.11 eV, the LUMO level was −2.95 eV, and the T1 level was 2.54 eV. These measurements were performed using the same method as described herein.

[0414] Next, lithium fluoride (LiF) was evaporated onto the electron transport layer 814 to form an electron injection layer 815 with a thickness of 1 nm.

[0415] Next, aluminum (Al) was evaporated onto the electron injection layer 815 to a film thickness of 120 nm, thereby forming the second electrode 802 .

[0416] <Method for Fabricating Light-Emitting Device 1B> Next, a method for fabricating the light-emitting device 1B will be described. The light-emitting device 1B differs from the light-emitting device 1A in the configuration of the hole transport layer.

[0417] That is, in the light-emitting device 1B, PCBBiF was deposited on the hole injection layer 811 by a vapor deposition method using resistance heating to a thickness of 90 nm, and then N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) was deposited to a thickness of 10 nm to form the hole transport layer 812.

[0418] The other components were fabricated in the same manner as in the light-emitting device 1A.

[0419] <Method for fabricating light-emitting device 1C> Next, a method for fabricating the light-emitting device 1C will be described. The light-emitting device 1C differs from the light-emitting device 1A in the configuration of the light-emitting layer.

[0420] That is, in the light-emitting device 1C, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited on the hole-transporting layer 812 by a resistance heating deposition method in a ratio of αN-βNPAnth:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to form a light-emitting layer 813 with a thickness of 25 nm. The HOMO level of αN-βNPAnth was −5.85 eV, the LUMO level was −2.74 eV, and the T1 level was 1.75 eV. These measurements were performed using the same method as described in this specification. Note that the T1 level was measured by mixing Ir(ppy)3 as a sensitizer.

[0421] The other components were fabricated in the same manner as in the light-emitting device 1A.

[0422] <Method for fabricating light-emitting device 1D> Next, a method for fabricating the light-emitting device 1D will be described. The light-emitting device 1D differs from the light-emitting device 1C in the configuration of the hole transport layer.

[0423] That is, in the light-emitting device 1D, PCBBiF was deposited on the hole injection layer 811 by a vapor deposition method using resistance heating to a thickness of 90 nm, and then N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) was deposited to a thickness of 10 nm to form the hole transport layer 812.

[0424] The other components were fabricated in the same manner as in the light-emitting device 1C.

[0425] The device structures of the light-emitting devices 1A to 1D are summarized in the table below, where X1 represents αN-βNPAnth-d8 or αN-βNPAnth.

[0426] [Table 1]

[0427] <Light-emitting device characteristics> The above light-emitting device was sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a sealant was applied around the element, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing), and then the characteristics of the light-emitting device were measured.

[0428] The luminance-current density characteristics of each light-emitting device are shown in FIG. 18, the luminance-voltage characteristics in FIG. 19, the current efficiency-luminance characteristics in FIG. 20, the current density-voltage characteristics in FIG. 21, and the electroluminescence spectrum in FIG.

[0429] The device also has a brightness of 1000 cd / m 2 The main characteristics in the vicinity are shown in the table below. A spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) was used to measure the luminance, CIE chromaticity, and electroluminescence spectrum.

[0430] [Table 2]

[0431] 18 to 22, it is clear that the light emitting devices 1A to 1D are highly efficient light emitting devices that require a low driving voltage and emit blue light with good color purity.

[0432] <Reliability test results> Furthermore, reliability tests were conducted on the light-emitting devices 1A to 1D. 2 The time change in normalized luminance during driving is shown in Figure 23. In Figure 23, the vertical axis shows normalized luminance (%), with the luminance at the start of light emission set to 100%, and the horizontal axis shows time (h).

[0433] 23, the LT90 (h), which is the time elapsed until the measured luminance decreased to 90% of the initial luminance, was 238 hours for light-emitting device 1A. On the other hand, the LT90 for light-emitting device 1B was 173 hours, the LT90 for light-emitting device 1C was 153 hours, and the LT90 for light-emitting device 1D was 155 hours. Therefore, it was found that light-emitting device 1A, which uses a deuterated organic compound in the light-emitting layer and the hole-transporting layer in contact with the light-emitting layer, has a significantly longer life than light-emitting devices 1B to 1D.

[0434] In other words, light-emitting device 1A was found to have approximately 1.5 times the reliability of light-emitting device 1D, in which neither the light-emitting layer nor the hole-transport layer was deuterated. Light-emitting device 1B, which used an organic compound with a deuterated light-emitting layer only, had approximately 1.1 times the reliability of light-emitting device 1D, and light-emitting device 1C, which used an organic compound with a deuterated hole-transport layer only, had the same reliability as light-emitting device 1D. In other words, the data from this example confirmed that deuterating both the light-emitting layer and the hole-transport layer produced a synergistic effect that could not be predicted from the results of deuterating only one of the light-emitting layer or the hole-transport layer.

[0435] This is thought to be because deuteration of the hole transport layer and the light-emitting layer increased the stability in the excited state or in the state in which carriers are retained, thereby improving the stability and durability of the compound and suppressing the deterioration of brightness due to operation of the light-emitting device.

[0436] Therefore, it was confirmed that the light-emitting device 1A according to one embodiment of the present invention exhibited high emission efficiency and was more reliable than the other light-emitting devices 1B to 1D. [Example]

[0437] In this example, light-emitting devices 2A to 2D, which are embodiments of the present invention, were fabricated.

[0438] The structural formulas of the organic compounds used in the light-emitting devices 2A to 2D are shown below.

[0439] [ka]

[0440] As shown in FIG. 17, each device has a structure in which a hole injection layer 811, a hole transport layer 812, a light-emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are sequentially stacked on a first electrode 801 formed on a glass substrate 800, and a second electrode 802 is stacked on the electron injection layer 815.

[0441] <Method for Fabricating Light-Emitting Device 2A> On a glass substrate 800, indium tin oxide containing silicon oxide (ITSO) was deposited by sputtering to a thickness of 110 nm to form a first electrode 801. The electrode area was 4 mm 2 (2mm x 2mm).

[0442] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water and baked at 200°C for 1 hour. -4The substrate was placed in a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and vacuum-baked at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, followed by natural cooling for 45 minutes.

[0443] Next, the substrate on which the first electrode 801 was formed was fixed to a substrate holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 801 was formed faced downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited on the first electrode 801 to a thickness of 10 nm such that the weight ratio of PCBBiF:OCHD-003 was 1:0.03, thereby forming a hole injection layer 811.

[0444] Next, PCBBiF was deposited on the hole injection layer 811 by a deposition method using resistance heating to a film thickness of 90 nm, and then N,N-bis{4-[(dibenzofuran-1,2,3,6,7,8,9-d7)-4-yl]phenyl-2,3,5,6-d4}-p-terphenyl-2,2′,2″,3,3′,3″,4″,5,5′,5″,6,6′,6″-d 13 -4-amine (abbreviation: DBfBB1TP-d 35 ) was evaporated to a thickness of 10 nm to form a hole transport layer 812.

[0445] Next, on the hole-transporting layer 812, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene-1,2,3,4,5,6,7,8-d8 (abbreviation: αN-βNPAnth-d8) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of αN-βNPAnth-d8:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813.

[0446] Next, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) was evaporated to a thickness of 10 nm on the light-emitting layer 813, followed by evaporation of 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) to a thickness of 15 nm to form an electron-transporting layer 814. The HOMO level, LUMO level, and T1 level of 2mPCCzPDBq were −5.63 eV, −2.98 eV, and 2.47 eV, respectively. These measurements were performed using the same method as described herein.

[0447] Next, lithium fluoride (LiF) was evaporated onto the electron transport layer 814 to form an electron injection layer 815 with a thickness of 1 nm.

[0448] Next, aluminum (Al) was evaporated onto the electron injection layer 815 to a film thickness of 120 nm, thereby forming the second electrode 802 .

[0449] <Method for Fabricating Light-Emitting Device 2B> Next, a method for fabricating the light-emitting device 2B will be described. The light-emitting device 2B differs from the light-emitting device 2A in the configuration of the hole transport layer.

[0450] That is, in the light-emitting device 2B, PCBBiF was deposited on the hole injection layer 811 by a vapor deposition method using resistance heating to a thickness of 90 nm, and then N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) was deposited to a thickness of 10 nm to form the hole transport layer 812.

[0451] The other components were fabricated in the same manner as the light-emitting device 2A.

[0452] <Method for fabricating light-emitting device 2C> Next, a method for fabricating the light-emitting device 2C will be described. The light-emitting device 2C differs from the light-emitting device 2A in the configuration of the light-emitting layer.

[0453] That is, in the light-emitting device 2C, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited on the hole-transport layer 812 by a resistance heating deposition method in a ratio of αN-βNPAnth:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to form a light-emitting layer 813 with a thickness of 25 nm.

[0454] The other components were fabricated in the same manner as the light-emitting device 2A.

[0455] <2D Light-Emitting Device Fabrication Method> Next, a method for fabricating the light-emitting device 2D will be described. The light-emitting device 2D differs from the light-emitting device 2C in the configuration of the hole transport layer.

[0456] That is, in the light-emitting device 2D, PCBBiF was deposited on the hole injection layer 811 by a vapor deposition method using resistance heating to a thickness of 90 nm, and then N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) was deposited on the hole injection layer 811 to a thickness of 10 nm to form the hole transport layer 812.

[0457] The other components were fabricated in the same manner as in the light-emitting device 2C.

[0458] The device structures of the light-emitting devices 2A to 2D are summarized in the table below. In the table, X2 represents αN-βNPAnth-d8 or αN-βNPAnth.

[0459] [Table 3]

[0460] <Light-emitting device characteristics> The above light-emitting device was sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a sealant was applied around the element, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing), and then the characteristics of the light-emitting device were measured.

[0461] The luminance-current density characteristics of each light-emitting device are shown in FIG. 24, the luminance-voltage characteristics in FIG. 25, the current efficiency-luminance characteristics in FIG. 26, the current density-voltage characteristics in FIG. 27, and the electroluminescence spectrum in FIG.

[0462] The device also has a brightness of 1000 cd / m 2 The main characteristics in the vicinity are shown in the table below. A spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) was used to measure the luminance, CIE chromaticity, and electroluminescence spectrum.

[0463] [Table 4]

[0464] 24 to 28, it is clear that the light emitting devices 2A to 2D are highly efficient light emitting devices that require a low driving voltage and emit blue light with good color purity.

[0465] <Reliability test results> Furthermore, reliability tests were conducted on the light-emitting devices 2A to 2D. 2 The time change in normalized luminance during driving is shown in Figure 29. In Figure 29, the vertical axis shows normalized luminance (%), with the luminance at the start of light emission set to 100%, and the horizontal axis shows time (h).

[0466] As shown in Figure 29, the LT90 (h), which is the time elapsed until the measured luminance decreased to 90% of the initial luminance, was 992 hours for light-emitting device 2A. Meanwhile, the LT90 for light-emitting device 2B was 738 hours, the LT90 for light-emitting device 2C was 822 hours, and the LT90 for light-emitting device 2D was 822 hours. Therefore, light-emitting device 2A, which uses a deuterated organic compound in the light-emitting layer and the hole-transport layer in contact with the light-emitting layer, was found to have higher reliability than light-emitting devices 2B to 2D. Furthermore, light-emitting device 2C, which uses a deuterated organic compound in the hole-transport layer, also showed slower degradation after LT90, demonstrating a longer lifespan.

[0467] In other words, light-emitting device 2A, which uses a deuterated organic compound in the light-emitting layer and the hole-transport layer in contact with the light-emitting layer, had a lifetime that was more than 100 hours longer than light-emitting device 2D, which had neither the light-emitting layer nor the hole-transport layer deuterated. Here, light-emitting device 2C, which uses a deuterated organic compound in the hole-transport layer, had a longer lifetime than light-emitting device 2D, while light-emitting device 2B, which uses an organic compound only in the light-emitting layer deuterated, had lower reliability than light-emitting device 2D. In other words, the data from this example confirmed that deuterating both the light-emitting layer and the hole-transport layer produced a synergistic effect that could not be predicted from the results of deuterating only one of the light-emitting layer or the hole-transport layer.

[0468] This is thought to be because deuteration of the hole transport layer and the light-emitting layer increased the stability in the excited state or in the state in which carriers are retained, thereby improving the stability and durability of the compound and suppressing the deterioration of brightness due to operation of the light-emitting device.

[0469] Therefore, it was confirmed that the light-emitting device 2A according to one embodiment of the present invention exhibited high luminous efficiency and was more reliable than the other light-emitting devices 2B to 2D. [Example]

[0470] In this example, light-emitting devices 3A and 3B according to one embodiment of the present invention were fabricated.

[0471] The structural formulae of the organic compounds used in light-emitting device 3A and light-emitting device 3B are shown below.

[0472] [ka]

[0473] As shown in FIG. 17, each device has a structure in which a hole injection layer 811, a hole transport layer 812, a light-emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are sequentially stacked on a first electrode 801 formed on a glass substrate 800, and a second electrode 802 is stacked on the electron injection layer 815.

[0474] <Method for Fabricating Light-Emitting Device 3A> On a glass substrate 800, indium tin oxide containing silicon oxide (ITSO) was deposited by sputtering to a thickness of 110 nm to form a first electrode 801. The electrode area was 4 mm 2 (2mm x 2mm).

[0475] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water and baked at 200°C for 1 hour. -4 The substrate was placed in a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and vacuum-baked at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, followed by natural cooling for 45 minutes.

[0476] Next, the substrate on which the first electrode 801 was formed was fixed to a substrate holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 801 was formed faced downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited on the first electrode 801 to a thickness of 10 nm such that the weight ratio of PCBBiF:OCHD-003 was 1:0.03, thereby forming a hole injection layer 811.

[0477] Next, PCBBiF was deposited on the hole injection layer 811 by a deposition method using resistance heating to a film thickness of 90 nm, and then N,N-bis{4-[(dibenzofuran-1,2,3,6,7,8,9-d7)-4-yl]phenyl-2,3,5,6-d4}-p-terphenyl-2,2′,2″,3,3′,3″,4″,5,5′,5″,6,6′,6″-d 13 -4-amine (abbreviation: DBfBB1TP-d 35 ) was evaporated to a thickness of 10 nm to form a hole transport layer 812.

[0478] Next, on the hole-transporting layer 812, 1-[10-(phenyl-2,3,4,5,6-d5)-9-anthryl]benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA-02-d5) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of Bnf(II)PhA-02-d5:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813. The HOMO level of Bnf(II)PhA-02-d5 was −5.86 eV, the LUMO level was −2.76 eV, and the T1 level was 1.75 eV. These measurements were performed using the same method as described in this specification. Note that the T1 level was measured by mixing Ir(ppy)3 as a sensitizer.

[0479] Next, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) was evaporated onto the light-emitting layer 813 to a thickness of 10 nm, and then 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) was evaporated onto the light-emitting layer 813 to a thickness of 15 nm, to form an electron-transporting layer 814.

[0480] Next, lithium fluoride (LiF) was evaporated onto the electron transport layer 814 to form an electron injection layer 815 with a thickness of 1 nm.

[0481] Next, aluminum (Al) was evaporated onto the electron injection layer 815 to a film thickness of 120 nm, thereby forming the second electrode 802 .

[0482] <Method for Fabricating Light-Emitting Device 3B> Next, a method for fabricating the light-emitting device 3B will be described. The light-emitting device 3B differs from the light-emitting device 3A in the configuration of the hole transport layer and the configuration of the light-emitting layer.

[0483] That is, in the light-emitting device 3B, PCBBiF was deposited on the hole injection layer 811 by a vapor deposition method using resistance heating to a thickness of 90 nm, and then N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) was deposited to a thickness of 10 nm to form the hole transport layer 812.

[0484] Subsequently, on the hole transport layer 812, 1-(10-phenyl-9-anthryl)benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA-02) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of Bnf(II)PhA-02:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813. The HOMO level of Bnf(II)PhA-02 was −5.86 eV and the LUMO level was −2.76 eV, measured by the same method as described herein.

[0485] The other components were fabricated in the same manner as in the light-emitting device 3A.

[0486] The device structures of the light-emitting devices 3A and 3B are summarized in the following table, where X3 represents Bnf(II)PhA-02-d5 or Bnf(II)PhA-02.

[0487] [Table 5]

[0488] <Light-emitting device characteristics> The above light-emitting device was sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a sealant was applied around the element, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing), and then the characteristics of the light-emitting device were measured.

[0489] The luminance-current density characteristics of each light-emitting device are shown in FIG. 30, the luminance-voltage characteristics in FIG. 31, the current efficiency-luminance characteristics in FIG. 32, the current density-voltage characteristics in FIG. 33, and the electroluminescence spectrum in FIG.

[0490] The device also has a brightness of 1000 cd / m2 The main characteristics in the vicinity are shown in the table below. A spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) was used to measure the luminance, CIE chromaticity, and electroluminescence spectrum.

[0491] [Table 6]

[0492] 30 to 34, it is clear that the light emitting devices 3A and 3B are highly efficient light emitting devices that require a low driving voltage and emit blue light with good color purity.

[0493] <Reliability test results> Furthermore, reliability tests were conducted on the light-emitting devices 3A and 3B. 2 The time change in normalized luminance during driving is shown in Figure 35. In Figure 35, the vertical axis shows normalized luminance (%), with the luminance at the start of light emission set to 100%, and the horizontal axis shows time (h).

[0494] 35, the LT90 (h), which is the time elapsed until the measured luminance decreased to 90% of the initial luminance, was 311 hours for light-emitting device 3A. On the other hand, the LT90 for light-emitting device 3B was 159 hours. Therefore, it was found that light-emitting device 3A, which uses deuterated organic compounds in the hole-transporting layer and the light-emitting layer, has higher reliability than light-emitting device 3B.

[0495] This is thought to be because deuteration of the hole transport layer and the light-emitting layer increased the stability in the excited state or in the state in which carriers are retained, thereby improving the stability and durability of the compound and suppressing the deterioration of brightness due to operation of the light-emitting device.

[0496] Therefore, it was confirmed that the light-emitting device 3A according to one embodiment of the present invention has better reliability than the light-emitting device 3B. [Example]

[0497] In this example, light-emitting devices 4A and 4B according to one embodiment of the present invention were fabricated.

[0498] The structural formulae of the organic compounds used in light-emitting device 4A and light-emitting device 4B are shown below.

[0499] [ka]

[0500] As shown in FIG. 17, each device has a structure in which a hole injection layer 811, a hole transport layer 812, a light-emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are sequentially stacked on a first electrode 801 formed on a glass substrate 800, and a second electrode 802 is stacked on the electron injection layer 815.

[0501] <Method for Fabricating Light-Emitting Device 4A> On a glass substrate 800, indium tin oxide containing silicon oxide (ITSO) was deposited by sputtering to a thickness of 110 nm to form a first electrode 801. The electrode area was 4 mm 2 (2mm x 2mm).

[0502] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water and baked at 200°C for 1 hour. -4 The substrate was placed in a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and vacuum-baked at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, followed by natural cooling for 45 minutes.

[0503] Next, the substrate on which the first electrode 801 was formed was fixed to a substrate holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 801 was formed faced downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited on the first electrode 801 to a thickness of 10 nm such that the weight ratio of PCBBiF:OCHD-003 was 1:0.03, thereby forming a hole injection layer 811.

[0504] Next, PCBBiF was deposited on the hole injection layer 811 by a deposition method using resistance heating to a film thickness of 90 nm, and then N,N-bis{4-[(dibenzofuran-1,2,3,6,7,8,9-d7)-4-yl]phenyl-2,3,5,6-d4}-p-terphenyl-2,2′,2″,3,3′,3″,4″,5,5′,5″,6,6′,6″-d 13 -4-amine (abbreviation: DBfBB1TP-d 35 ) was evaporated to a thickness of 10 nm to form a hole transport layer 812.

[0505] Next, on the hole-transporting layer 812, 1-[10-(phenyl-2,3,4,5,6-d5)-9-anthryl]benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA-02-d5) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of Bnf(II)PhA-02-d5:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813.

[0506] Next, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) was evaporated on the light-emitting layer 813 to a thickness of 10 nm, and then 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) was evaporated on the light-emitting layer 813 to a thickness of 15 nm to form an electron-transporting layer 814.

[0507] Next, lithium fluoride (LiF) was evaporated onto the electron transport layer 814 to form an electron injection layer 815 with a thickness of 1 nm.

[0508] Next, aluminum (Al) was evaporated onto the electron injection layer 815 to a film thickness of 120 nm, thereby forming the second electrode 802 .

[0509] <Method for Fabricating Light-Emitting Device 4B> Next, a method for fabricating the light-emitting device 4B will be described. The light-emitting device 4B differs from the light-emitting device 4A in the configuration of the hole transport layer and the configuration of the light-emitting layer.

[0510] That is, in the light-emitting device 4B, PCBBiF was deposited on the hole injection layer 811 by a deposition method using resistance heating to a thickness of 90 nm, and then N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) was deposited to a thickness of 10 nm to form the hole transport layer 812.

[0511] Subsequently, on the hole transport layer 812, 1-(10-phenyl-9-anthryl)benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA-02) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of Bnf(II)PhA-02:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813.

[0512] The other components were fabricated in the same manner as in the light-emitting device 4A.

[0513] The device structures of the light-emitting devices 4A and 4B are summarized in the following table, where X4 represents Bnf(II)PhA-02-d5 or Bnf(II)PhA-02.

[0514] [Table 7]

[0515] <Light-emitting device characteristics> The above light-emitting device was sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a sealant was applied around the element, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing), and then the characteristics of the light-emitting device were measured.

[0516] The luminance-current density characteristics of each light-emitting device are shown in FIG. 36, the luminance-voltage characteristics in FIG. 37, the current efficiency-luminance characteristics in FIG. 38, the current density-voltage characteristics in FIG. 39, and the electroluminescence spectrum in FIG.

[0517] The device also has a brightness of 1000 cd / m 2 The main characteristics in the vicinity are shown in the table below. A spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) was used to measure the luminance, CIE chromaticity, and electroluminescence spectrum.

[0518] [Table 8]

[0519] 36 to 40, it is clear that light-emitting devices 4A and 4B are highly efficient light-emitting devices that require a low driving voltage and emit blue light with good color purity.

[0520] <Reliability test results> Furthermore, reliability tests were conducted on the light-emitting devices 4A and 4B. 2 The change in normalized luminance over time during driving is shown in Figure 41. In Figure 41, the vertical axis shows normalized luminance (%), with the luminance at the start of light emission set to 100%, and the horizontal axis shows time (h).

[0521] 41, the LT95 (h), which is the time elapsed until the measured luminance decreased to 95% of the initial luminance, was 198 hours for light-emitting device 4A. On the other hand, the LT95 for light-emitting device 4B was 115 hours. Therefore, the data of this example demonstrate that light-emitting device 4A, which uses a deuterated organic compound in the light-emitting layer and the hole-transporting layer in contact with the light-emitting layer, has higher reliability than light-emitting device 4B.

[0522] This is thought to be because deuteration of the hole transport layer and the light-emitting layer increased the stability in the excited state or in the state in which carriers are retained, thereby improving the stability and durability of the compound and suppressing the deterioration of brightness due to operation of the light-emitting device.

[0523] Therefore, it was confirmed that the light-emitting device 4A according to one embodiment of the present invention has better reliability than the light-emitting device 4B. [Example]

[0524] In this example, light-emitting devices 5A and 5B according to an embodiment of the present invention were fabricated.

[0525] The structural formulae of the organic compounds used in light-emitting device 5A and light-emitting device 5B are shown below.

[0526] [ka]

[0527] As shown in FIG. 17, each device has a structure in which a hole injection layer 811, a hole transport layer 812, a light-emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are sequentially stacked on a first electrode 801 formed on a glass substrate 800, and a second electrode 802 is stacked on the electron injection layer 815.

[0528] <Method for Fabricating Light-Emitting Device 5A> On a glass substrate 800, indium tin oxide containing silicon oxide (ITSO) was deposited by sputtering to a thickness of 110 nm to form a first electrode 801. The electrode area was 4 mm 2 (2mm x 2mm).

[0529] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water and baked at 200°C for 1 hour. -4 The substrate was placed in a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and vacuum-baked at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, followed by natural cooling for 45 minutes.

[0530] Next, the substrate on which the first electrode 801 was formed was fixed to a substrate holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 801 was formed faced downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited on the first electrode 801 to a thickness of 10 nm such that the weight ratio of PCBBiF:OCHD-003 was 1:0.03, thereby forming a hole injection layer 811.

[0531] Next, PCBBiF was deposited on the hole injection layer 811 by a deposition method using resistance heating to a film thickness of 90 nm, and then N,N-bis(4-biphenyl-2,2',3,3',4',5,5',6,6'-d9)-6-(phenyl-2,3,4,5,6-d5)benzo[b]naphtho[1,2-d]furan(1,2,3,4,5,9,10,11-d8)-8-amine (abbreviation: BBABnf-d 31 ) was evaporated to a thickness of 10 nm to form a hole transport layer 812.

[0532] Next, on the hole-transporting layer 812, 1-[10-(phenyl-2,3,4,5,6-d5)-9-anthryl]benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA-02-d5) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of Bnf(II)PhA-02-d5:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813.

[0533] Next, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) was evaporated onto the light-emitting layer 813 to a thickness of 10 nm, and then 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) was evaporated onto the light-emitting layer 813 to a thickness of 15 nm, to form an electron-transporting layer 814.

[0534] Next, lithium fluoride (LiF) was evaporated onto the electron transport layer 814 to form an electron injection layer 815 with a thickness of 1 nm.

[0535] Next, aluminum (Al) was evaporated onto the electron injection layer 815 to a film thickness of 120 nm, thereby forming the second electrode 802 .

[0536] <Method for Fabricating Light-Emitting Device 5B> Next, a method for fabricating the light-emitting device 5B will be described. The light-emitting device 5B differs from the light-emitting device 5A in the configuration of the hole transport layer and the configuration of the light-emitting layer.

[0537] That is, in the light-emitting device 5B, PCBBiF was deposited on the hole injection layer 811 by a deposition method using resistance heating to a thickness of 90 nm, and then N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) was deposited to a thickness of 10 nm to form the hole transport layer 812.

[0538] Subsequently, on the hole transport layer 812, 1-(10-phenyl-9-anthryl)benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA-02) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of Bnf(II)PhA-02:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813.

[0539] The other components were fabricated in the same manner as in the light-emitting device 5A.

[0540] The device structures of light-emitting device 5A and light-emitting device 5B are summarized in the following table, where X5 represents Bnf(II)PhA-02-d5 or Bnf(II)PhA-02.

[0541] [Table 9]

[0542] <Light-emitting device characteristics> The above light-emitting device was sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a sealant was applied around the element, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing), and then the characteristics of the light-emitting device were measured.

[0543] The luminance-current density characteristics of each light-emitting device are shown in FIG. 42, the luminance-voltage characteristics in FIG. 43, the current efficiency-luminance characteristics in FIG. 44, the current density-voltage characteristics in FIG. 45, and the electroluminescence spectrum in FIG.

[0544] The device also has a brightness of 1000 cd / m 2 The main characteristics in the vicinity are shown in the table below. A spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) was used to measure the luminance, CIE chromaticity, and electroluminescence spectrum.

[0545] [Table 10]

[0546] 30 to 46, it is clear that light emitting device 5A and light emitting device 5B are highly efficient light emitting devices that require a low driving voltage and emit blue light with good color purity.

[0547] <Reliability test results> Furthermore, reliability tests were conducted on the light-emitting devices 5A and 5B. 2 The time change in normalized luminance during driving is shown in Figure 47. In Figure 47, the vertical axis shows normalized luminance (%), with the luminance at the start of light emission set to 100%, and the horizontal axis shows time (h).

[0548] 47, the LT95 (h), which is the time elapsed until the measured luminance decreased to 95% of the initial luminance, was 105 hours for light-emitting device 5A. On the other hand, the LT95 for light-emitting device 5B was 55 hours. Therefore, it was found that light-emitting device 5A, which uses deuterated organic compounds in the hole-transporting layer and the light-emitting layer, has higher reliability than light-emitting device 5B.

[0549] This is thought to be because deuteration of the hole transport layer and the light-emitting layer increased the stability in the excited state or in the state in which carriers are retained, thereby improving the stability and durability of the compound and suppressing the deterioration of brightness due to operation of the light-emitting device.

[0550] Therefore, it was confirmed that the light-emitting device 5A according to one embodiment of the present invention has better reliability than the light-emitting device 5B. [Example]

[0551] In this example, a light-emitting device 6A and a light-emitting device 6B according to one embodiment of the present invention were fabricated.

[0552] The structural formulae of the organic compounds used in the light-emitting devices 6A and 6B are shown below.

[0553] [ka]

[0554] As shown in FIG. 17, each device has a structure in which a hole injection layer 811, a hole transport layer 812, a light-emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are sequentially stacked on a first electrode 801 formed on a glass substrate 800, and a second electrode 802 is stacked on the electron injection layer 815.

[0555] <Method for Fabricating Light-Emitting Device 6A> On a glass substrate 800, indium tin oxide containing silicon oxide (ITSO) was deposited by sputtering to a thickness of 110 nm to form a first electrode 801. The electrode area was 4 mm2 (2mm x 2mm).

[0556] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water and baked at 200°C for 1 hour. -4 The substrate was placed in a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and vacuum-baked at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, followed by natural cooling for 45 minutes.

[0557] Next, the substrate on which the first electrode 801 was formed was fixed to a substrate holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 801 was formed faced downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited on the first electrode 801 to a thickness of 10 nm such that the weight ratio of PCBBiF:OCHD-003 was 1:0.03, thereby forming a hole injection layer 811.

[0558] Next, PCBBiF was deposited on the hole injection layer 811 by a deposition method using resistance heating to a film thickness of 90 nm, and then N,N-bis(4-biphenyl-2,2',3,3',4',5,5',6,6'-d9)-6-(phenyl-2,3,4,5,6-d5)benzo[b]naphtho[1,2-d]furan(1,2,3,4,5,9,10,11-d8)-8-amine (abbreviation: BBABnf-d 31 ) was evaporated to a thickness of 10 nm to form a hole transport layer 812.

[0559] Next, on the hole-transporting layer 812, 1-[10-(phenyl-2,3,4,5,6-d5)-9-anthryl]benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA-02-d5) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of Bnf(II)PhA-02-d5:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813.

[0560] Next, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) was evaporated on the light-emitting layer 813 to a thickness of 10 nm, and then 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) was evaporated on the light-emitting layer 813 to a thickness of 15 nm to form an electron-transporting layer 814.

[0561] Next, lithium fluoride (LiF) was evaporated onto the electron transport layer 814 to form an electron injection layer 815 with a thickness of 1 nm.

[0562] Next, aluminum (Al) was evaporated onto the electron injection layer 815 to a film thickness of 120 nm, thereby forming the second electrode 802 .

[0563] <Method for producing light-emitting device 6B> Next, a method for fabricating the light-emitting device 6B will be described. The light-emitting device 6B differs from the light-emitting device 6A in the configuration of the hole transport layer and the configuration of the light-emitting layer.

[0564] That is, in the light-emitting device 6B, PCBBiF was deposited on the hole injection layer 811 by a deposition method using resistance heating to a thickness of 90 nm, and then N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) was deposited to a thickness of 10 nm to form the hole transport layer 812.

[0565] Subsequently, on the hole transport layer 812, 1-(10-phenyl-9-anthryl)benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA-02) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) were co-deposited by a vapor deposition method using resistance heating in a ratio of Bnf(II)PhA-02:3,10PCA2Nbf(IV)-02 = 1:0.015 (weight ratio) to a thickness of 25 nm, thereby forming a light-emitting layer 813.

[0566] The other components were fabricated in the same manner as the light-emitting device 6A.

[0567] The device structures of the light-emitting devices 6A and 6B are summarized in the following table, where X6 represents Bnf(II)PhA-02-d5 or Bnf(II)PhA-02.

[0568] [Table 11]

[0569] <Light-emitting device characteristics> The above light-emitting device was sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a sealant was applied around the element, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing), and then the characteristics of the light-emitting device were measured.

[0570] The luminance-current density characteristics of each light-emitting device are shown in FIG. 48, the luminance-voltage characteristics in FIG. 49, the current efficiency-luminance characteristics in FIG. 50, the current density-voltage characteristics in FIG. 51, and the electroluminescence spectrum in FIG.

[0571] The device also has a brightness of 1000 cd / m 2 The main characteristics in the vicinity are shown in the table below. A spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) was used to measure the luminance, CIE chromaticity, and electroluminescence spectrum.

[0572] [Table 12]

[0573] 48 to 52, it is clear that the light emitting devices 6A and 6B are highly efficient light emitting devices that require a low driving voltage and emit blue light with good color purity.

[0574] <Reliability test results> Furthermore, reliability tests were conducted on the light-emitting devices 6A and 6B. 2 The change in normalized luminance over time during driving is shown in Figure 53. In Figure 53, the vertical axis shows normalized luminance (%), with the luminance at the start of light emission set to 100%, and the horizontal axis shows time (h).

[0575] 53, the LT95 (h), which is the time elapsed until the measured luminance decreased to 95% of the initial luminance, was 184 hours for light-emitting device 6A. On the other hand, the LT95 for light-emitting device 6B was 105 hours. Therefore, it was found that light-emitting device 6A, which uses a deuterated organic compound in the light-emitting layer and the hole-transporting layer in contact with the light-emitting layer, has higher reliability than light-emitting device 6B.

[0576] This is thought to be because deuteration of the hole transport layer and the light-emitting layer increased the stability in the excited state or in the state in which carriers are retained, thereby improving the stability and durability of the compound and suppressing the deterioration of brightness due to operation of the light-emitting device.

[0577] Therefore, it was confirmed that the light-emitting device 6A according to one embodiment of the present invention has better reliability than the light-emitting device 6B.

[0578] <Physical properties of compounds used in the examples> The HOMO levels and LUMO levels of the materials used in Examples 1 to 6 are shown below. These values ​​were measured in the same manner as described in this specification.

[0579] [Table 13]

[0580] As can be seen from the table above, the light-emitting device of this example has a structure in which the difference between the HOMO level of the host material in the light-emitting layer and the HOMO level of the guest material is 0.44 eV, which means that the HOMO level of the guest material is high and hole trapping occurs. Furthermore, the difference between the LUMO level of the host material in the light-emitting layer and the LUMO level of the material used in the electron transport layer in contact with the light-emitting layer is 0.21 eV, which are close values, so it can be said that the structure has a high electron injection ability from the electron transport layer to the light-emitting layer.

[0581] In other words, in a light-emitting device having such a configuration, it is believed that by using a deuterium compound in the hole transport layer in contact with the light-emitting layer, it is possible to provide a light-emitting device with high luminous efficiency and in which luminance degradation due to operation of the light-emitting device is suppressed.

[0582] (Reference synthesis example 1) In this synthesis example, N,N-bis(4-biphenyl-2,2',3,3',4',5,5',6,6'-d9)-6-(phenyl-2,3,4,5,6-d5)benzo[b]naphtho[1,2-d]furan(1,2,3,4,5,9,10,11-d8)-8-amine (abbreviation: BBABnf-d 31 The synthesis method of BBABnf-d will be specifically explained. 31 The structure is shown below.

[0583] [ka]

[0584] <Synthesis Example 1> The following describes the introduction of deuterated substituents to BBABnf-d 31 The synthesis method will be explained.

[0585] Step 1: Synthesis of 8-iodo-6-(phenyl-2,3,4,5,6-d5)benzo[b]naphtho[1,2-d]furan (1,2,3,4,5,9,10,11-d8) First, 10 g (24 mmol) of 8-iodo-6-phenylbenzo[b]naphtho[1,2-d]furan and 40 mL of toluene-d8 were added to a 100 mL three-neck flask. The mixture was heated to 100 °C under a nitrogen stream to confirm the dissolution of 8-iodo-6-phenylbenzo[b]naphtho[1,2-d]furan. 6.9 g (25 mmol) of molybdenum chloride (MoCl5) was added to the solution and stirred at 100 °C for 5 minutes. 10 mL of ethanol and 30 mL of water were slowly added to the mixture. The mixture was suction filtered to remove insoluble matter, and then the organic and aqueous phases were separated using chloroform and purified water. The organic phase was washed once with saturated aqueous sodium bicarbonate and once with saturated aqueous sodium thiosulfate. The organic phase was dehydrated over magnesium sulfate and gravity filtered using pleated filter paper. The filtrate was concentrated to obtain 7.3 g of a reddish-brown solid containing the desired product. This was purified by liquid chromatography to obtain 5.6 g (55% yield) of the target yellow solid. The synthesis scheme (a1-1) of <Step 1> is shown below.

[0586] [ka]

[0587] The molecular weight of the yellow solid obtained in Step 1 above was measured using LC / MS analysis. As a result, a signal was observed at m / z 433, which corresponds to the calculated mass of the target compound, 433, indicating that 8-iodo-6-(phenyl-2,3,4,5,6-d5)benzo[b]naphtho[1,2-d]furan (1,2,3,4,7,8,9,10,11-d8) was obtained.

[0588] <Step 2:BBABnf-d 31 Synthesis of> Next, 5.6 g (13 mmol) of 8-iodo-6-(phenyl-2,3,4,5,6-d5)benzo[b]naphtho[1,2-d]furan (1,2,3,4,7,8,9,10,11-d8) obtained in Step 1, 3.4 g (9.9 mmol) of N,N-bis(4-biphenylyl-2,2',3,3',4',5,5',6,6'-d9) and 1.0 g (1.0 mmol) of N,N-bis(4-biphenylyl-2,2',3,3',4',5,5',6,6'-d9) were added to a 200 mL three-neck flask. t 3.0 g (31 mmol) of BuONa and 75 mL of toluene were added. The mixture was degassed by stirring under reduced pressure, and the atmosphere in the flask was replaced with nitrogen, and then the reaction solution was heated to 100°C. t 0.5 mL (0.37 mmol) of (Bu)3 (20 wt% hexane solution) and 73 mg (0.13 mmol) of Pd(dba)2 were added and stirred at 120 °C for 2 hours, then cooled to room temperature. Subsequently, this mixture was heated to 80 °C, and 0.31 g (0.75 mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (abbreviation: SPhos) and 0.15 g (0.27 mmol) of Pd(dba)2 were added and stirred at 120 °C for 7 hours. Toluene was added to this mixture, and the resulting mixture was suction filtered through alumina, Celite (Fujifilm Wako Pure Chemical Industries, Ltd., catalog number: 537-02305), and Florisil (Fujifilm Wako Pure Chemical Industries, Ltd., catalog number: 066-05265). The filtrate was concentrated to obtain 8.1 g of a pale yellow solid containing the target compound. This solid was purified by liquid chromatography, then dissolved in toluene, and ethanol was added to the solution. The precipitated solid was collected by suction filtration to obtain 6.1 g (95% yield) of the target pale yellow solid. The synthesis scheme (a1-2) of <Step 2> is shown below.

[0589] [ka]

[0590] The pale yellow solid obtained in Step 2 above was analyzed by LC / MS to measure its molecular weight. As a result, a signal was observed at m / z 644, which corresponds to the calculated mass of the target compound, BBABnf-d 31 It was found that the following was obtained.

[0591] As in Synthesis Example 1, the raw materials for each partial structure are deuterated, and then the deuterated partial structures are subjected to a coupling reaction to obtain BBABnf-d 31 When the molecular weight was measured using LC / MS analysis, a signal was observed at m / z 644, which corresponds to the calculated mass of the target compound of 644. Therefore, the method of synthesizing the target compound by a coupling reaction after deuterizing the raw materials of each partial structure, as in Synthesis Example 1, is a preferable synthesis method for synthesizing a compound having a molecular structure in which all protons are replaced with deuterium, and from the viewpoint of improving the deuteration rate.

[0592] (Reference synthesis example 2) In this synthesis example, N,N-bis(4-biphenyl-2,2',3,3',4',5,5',6,6'-d9)-6-(phenyl-2,3,4,5,6-d5)benzo[b]naphtho[1,2-d]furan(1,2,3,4,5,9,10,11-d8)-8-amine (abbreviation: BBABnf-d 31 A synthesis method different from Reference Synthesis Example 1 for BBABnf-d will be specifically described. 31 The structure is shown below.

[0593] [ka]

[0594] <Synthesis Example 2> Below, we will deuterate N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf) to obtain BBABnf-d 31 A method for synthesizing the above will be described.

[0595] <Step 1: BBABnf-d 31 Synthesis of> First, 1.2 g (2.0 mmol) of N,N-bis(4-biphenylyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine and 21 mL of toluene-d8 were added to a 50 mL three-neck flask. The mixture was heated to 100 °C under a nitrogen stream to confirm the dissolution of N,N-bis(4-biphenylyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine. 512 mg (1.8 mmol) of molybdenum chloride (MoCl5) was added to the solution and stirred at 100 °C for 10 hours. A small amount of the reaction solution was sampled and analyzed by LC / MS. The molecular weight was determined using LC / MS. Signals were mainly observed at m / z 628-631, with a signal at m / z 644, relative to the calculated mass of the target compound. These results confirmed the formation of the target compound, BBABnf-d. 31 Besides BBABnf-d 15 ~BBABnf-d 18 It was suggested that the compound BBABnf-d was also produced. 15 ~BBABnf-d 18 Examples of the compound include organic compounds represented by structural formulas (102) to (105) described in the specific examples. The synthesis scheme (a2-1) of <Step 1> is shown below.

[0596] [ka]

[0597] Furthermore, when synthesis is performed as in Synthesis Example 2, the deuteration reaction needs to be performed only once, reducing synthesis costs and enabling deuterium-substituted compounds to be obtained at low cost. Furthermore, since trifluoromethanesulfonic acid is not used, the possibility of the target product containing fluorine as an impurity is reduced, which is highly advantageous. However, the presence of fluorine in the organic EL material is undesirable because it increases concerns about a decrease in the reliability or luminous efficiency of devices fabricated using the material, and therefore requires purification to reduce the fluorine concentration. By performing the deuteration reaction as in Synthesis Example 2, a fluorine-free deuterated organic EL material can be provided.

[0598] (Reference synthesis example 3) In this synthesis example, N,N-bis{4-[(dibenzofuran-1,2,3,6,7,8,9-d7)-4-yl]phenyl-2,3,5,6-d4}-p-terphenyl-2,2′,2″,3,3′,3″,4″,5,5′,5″,6,6′,6″-d 13 -4-amine (abbreviation: DBfBB1TP-d 35 The synthesis method of DBfBB1TP-d will be specifically explained. 35 The structure is shown below.

[0599] [ka]

[0600] <Step 1-1: Synthesis of 4,4'-di(dibenzofuran-1,2,3,6,7,8,9-d7-4-yl)diphenylamine-2,2',3,3',5,5',6,6'-d8> First, 1.0 g (2.0 mmol) of 4,4'-di(dibenzofuran-4-yl)diphenylamine and 20 mL of toluene-d8 were added to a 50 mL three-neck flask. This mixture was heated to 100 °C under a nitrogen stream to confirm that 4,4'-di(dibenzofuran-4-yl)diphenylamine had dissolved. 1.6 mL (14 mmol) of trifluoromethanesulfonic acid (TfOH) was added to this solution, and the mixture was stirred at 100 °C for 8 hours. A small amount of the resulting solution was sampled, and the molecular weight was measured by liquid chromatography mass spectrometry (LC / MS).

[0601] In the LC / MS analysis, LC (liquid chromatography) separation was performed using an Ultimate 3000 manufactured by Thermo Fisher Scientific, and MS analysis (mass spectrometry) was performed using a Q Exactive manufactured by Thermo Fisher Scientific.

[0602] LC / MS analysis revealed a signal at m / z 523, corresponding to the calculated mass of the target compound, 523. Therefore, it was determined that 4,4'-di(dibenzofuran-1,2,3,6,7,8,9-d7-4-yl)diphenylamine-2,2',3,3',5,5',6,6'-d8 had been produced. Furthermore, the post-reaction treatment and purification were carried out together with the product synthesized in the next step, Step 1-2, and will be described later.

[0603] <Step 1-2: Synthesis of 4,4'-di(dibenzofuran-1,2,3,6,7,8,9-d7-4-yl)diphenylamine-2,2',3,3',5,5',6,6'-d8> In addition, 3.0 g (6.0 mmol) of 4,4'-di(dibenzofuran-4-yl)diphenylamine and 68 mL of toluene-d8 were added to a 200 mL three-neck flask. This mixture was heated to 100 °C under a nitrogen stream, and the 4,4'-di(dibenzofuran-4-yl)diphenylamine was confirmed to have dissolved. 4.3 mL (49 mmol) of TfOH was added to this solution and stirred at 100 °C for 4 hours. After cooling to room temperature, the reaction solution from <Step 1-1>, chloroform, and purified water were added and the mixture was separated. The organic phase was washed twice with water and three times with saturated aqueous sodium bicarbonate solution. The organic phase was dehydrated with magnesium sulfate and gravity filtered using pleated filter paper. The filtrate was concentrated to obtain 4.6 g of the desired white solid. The synthesis scheme (b-1) for <Step 1-1> and <Step 1-2> is shown below.

[0604] [ka]

[0605] <Step 2:DBfBB1TP-d 35 Synthesis of> Next, 2.7 g (5.2 mmol) of 4,4'-di(dibenzofuran-1,2,3,6,7,8,9-d7-4-yl)diphenylamine-2,2',3,3',5,5',6,6'-d8 obtained in <Step 1-1> and <Step 1-2>, 4-bromo-p-terphenyl-2,2',2'',3,3',3'',4'',5,5',5'',6,6',6''-d 13 2.5g (7.8mmol), sodium t-butoxide (abbreviation: t 1.5 g (16 mmol) of butyl phosphate (BuONa) and 63 mL of toluene were added. The mixture was degassed by stirring under reduced pressure, and the atmosphere in the flask was replaced with nitrogen, and then the mixture was heated to 100°C. Tri-tert-butylphosphine (abbreviation: P( t0.3 mL (0.1 mmol) of 10 wt% hexane solution of bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd(dba)2) was added, and the mixture was stirred at 120 °C for 2 hours. The next day, the reaction solution was heated to 80 °C, and then P( t 0.5 mL (0.2 mmol) of Pd(dba)3 (10 wt% hexane solution) and 31 mg (54 μmol) of Pd(dba)2 were added and stirred at 120 °C for 5 hours. Toluene was added to the reaction solution and stirred at 100 °C. The resulting mixture was suction filtered through alumina, Celite (Fujifilm Wako Pure Chemical Industries, Ltd., catalog number: 537-02305), and Florisil (Fujifilm Wako Pure Chemical Industries, Ltd., catalog number: 066-05265). The filtrate was concentrated to obtain 4.2 g of a pale yellow solid containing the target compound. This solid was purified by liquid chromatography to obtain 2.7 g of the target white solid (68% yield). The synthesis scheme (b-2) of <Step 2> is shown below.

[0606] [ka]

[0607] The resulting white solid (2.7 g) was purified by train sublimation. The sublimation purification was carried out by heating the solid at 345°C for 24 hours under a pressure of 2.78 Pa. After sublimation purification, 2.3 g of the target white solid was obtained with a recovery rate of 86%.

[0608] Furthermore, when the molecular weight of the white solid obtained in step 2 was measured using LC / MS analysis, a signal was observed at m / z 764, which corresponds to the calculated mass of the target compound of 764. From these results, it was confirmed that DBfBB1TP-d 35 It was found that the following was obtained.

[0609] (Reference synthesis example 4) In this example, the organic compound of the present invention, N-[4-(1-naphthyl-2,3,4,5,6,7,8-d7)phenyl-2,3,5,6-d4]-N-[(9,9'-spirobi[9H-fluorene]-1,3,4,5,6,7,8,1',2',3',4',5',6',7',8'-d 15 This article describes a synthesis method for [benzo[b]naphtho[2,1-d]furan-1,2,3,4,5,6,7,8,9-d9]-10-amine (abbreviation: SFNBaBnf(10)-d35). The structure of SFNBaBnf(10)-d35 is shown below.

[0610] [ka]

[0611] Step 1: N-[4-(1-naphthyl-2,3,4,5,6,7,8-d7)phenyl-2,3,5,6-d4]-(9,9'-spirobi[9H-fluorene]-1,3,4,5,6,7,8,1',2',3',4',5',6',7',8'-d 15 Synthesis of 2-amine A 200 mL Erlenmeyer flask was charged with 11.5 g (21.5 mmol) of N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine and 855 mL of toluene-d. The mixture was stirred at 70 °C under a nitrogen stream. 5.0 mL (57 mmol) of trifluoromethanesulfonic acid (TfOH) was added to the solution, and the mixture was stirred at 100 °C for 3 hours. After cooling to room temperature, water was slowly added to the reaction solution, and the resulting mixture was transferred to a separatory funnel and extracted with toluene. The resulting organic phase was washed twice with aqueous sodium hydroxide. Magnesium sulfate was added to the organic phase for dehydration, and after a predetermined time, the mixture was gravity filtered using pleated filter paper. The resulting filtrate was concentrated to yield 12.1 g of a green solid. Ethyl acetate and toluene were added to this solid to obtain a suspension. The suspension was heated with a heat gun, cooled to room temperature, and filtered by suction to obtain 7.20 g (60% yield) of the target pale greenish-white solid. The synthesis scheme (c-1) of Step 1 is shown below.

[0612] [ka]

[0613] The pale greenish-white solid obtained in step 1 was subjected to molecular weight measurement using LC / MS. A signal was observed at m / z 559, corresponding to the calculated mass of 559 for the target compound. This result indicated that the compound was N-[4-(1-naphthyl-2,3,4,5,6,7,8-d7)phenyl-2,3,5,6-d4]-(9,9'-spirobi[9H-fluorene]-1,3,4,5,6,7,8,1',2',3',4',5',6',7',8'-d 15 )-2-amine was obtained.

[0614] Step 2: Synthesis of 10-bromobenzo[b]naphtho[2,1-d]furan-1,2,3,4,5,6,7,8,9-d9 A 200 mL three-neck flask was charged with 8.1 g (27 mmol) of 10-bromobenzo[b]naphtho[2,1-d]furan and 821 mL of toluene-d. The mixture was heated to 70 °C under a nitrogen stream, and the 10-bromobenzo[b]naphtho[2,1-d]furan was confirmed to have dissolved. 7.2 g (26 mmol) of molybdenum chloride (MoCl5) was slowly added to the solution and stirred at 70 °C for 3 minutes. After cooling to room temperature, water was added to the reaction solution, which was then transferred to a separatory funnel and extracted with chloroform. The organic phase was washed twice with purified water and twice with saturated aqueous sodium bicarbonate. Magnesium sulfate was added to the resulting organic phase for dehydration, and after the specified time had elapsed, gravity filtration was performed using pleated filter paper. The resulting filtrate was concentrated to yield 8.7 g of a viscous brown oil. After dissolving this oil in a small amount of toluene, the oil was purified by silica gel chromatography (eluent: hexane: toluene = 20:1) to obtain 5.6 g (68% yield) of the desired pale yellow solid. The synthesis scheme (c-2) of step 2 is shown below.

[0615] [ka]

[0616] The molecular weight of the pale yellow solid obtained in Step 2 was measured using LC / MS analysis. As a result, a signal was observed at m / z 305, which corresponds to the calculated mass of the target compound of 305, indicating that 10-bromobenzo[b]naphtho[2,1-d]furan-1,2,3,4,5,6,7,8,9-d9 was obtained.

[0617] <Step 3: Synthesis of SFNBaBnf(10)-d35> In a 200 mL three-neck flask, add N-[4-(1-naphthyl-2,3,4,5,6,7,8-d7)phenyl-2,3,5,6-d4]-(9,9'-spirobi[9H-fluorene]-1,3,4,5,6,7,8,1',2',3',4',5',6',7',8'-d) 15 )-2-amine 3.6 g (6.4 mmol), 10-bromobenzo[b]naphtho[2,1-d]furan-1,2,3,4,5,6,7,8,9-d9 obtained in Step 2 2.2 g (7.1 mmol), sodium t-butoxide (abbreviation: t 1.9 g (20 mmol) of (BuONa) and 64 mL of toluene were added. The mixture was degassed by stirring under reduced pressure, and the atmosphere in the flask was replaced with nitrogen, and then the mixture was heated to 110°C. The reaction solution was added to tri-tert-butylphosphine (abbreviated as P( t 0.3 mL (0.15 mmol) of bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd(dba)2) (10 wt% hexane solution) was added and stirred at 120 °C for 6 hours. Toluene was added to this mixture, and the mixture was stirred at 80 °C. The resulting mixture was suction filtered through alumina, Celite (Fujifilm Wako Pure Chemical Industries, Ltd., catalog number: 537-02305), and Florisil (Fujifilm Wako Pure Chemical Industries, Ltd., catalog number: 066-05265). The filtrate was concentrated to obtain 5.6 g of a pale yellow solid containing the target compound. This solid was purified by liquid chromatography (mobile phase: chloroform) to obtain 4.5 g of the target white solid (89% yield). The synthesis scheme (c-3) for Step 3 is shown below.

[0618] [Chem.]

[0619] The obtained 2.6 g of white solid was purified by sublimation using the train sublimation method. The sublimation purification was carried out by flowing argon at 10 mL / min and heating the solid at a pressure of 2.84 Pa and 310 °C for 16 hours. After sublimation purification, 2.15 g of the white solid of the target product was obtained with a recovery rate of 83%.

[0620] The obtained white solid was measured for its molecular weight using LC / MS analysis. As a result, a signal was observed at m / z 785 with respect to the calculated mass 785 of the target product, and it was found that SFNBaBnf(10)-d35 was obtained.

[0621] (Reference Synthesis Example 5) (21) In...

Claims

1. At least a light-emitting layer and a hole-transporting layer are provided between a pair of electrodes, the light-emitting layer includes a first compound that is a host material and a second compound that is a guest material; the hole transport layer comprises a third compound; the HOMO level of the second compound is higher than the HOMO level of the first compound; The light-emitting device, wherein the first compound and the third compound are compounds having deuterium.

2. At least a light-emitting layer and a hole-transporting layer are provided between a pair of electrodes, the hole transport layer is provided in contact with the light emitting layer, the light-emitting layer includes a first compound that is a host material and a second compound that is a guest material; the hole transport layer comprises a third compound; the HOMO level of the second compound is higher than the HOMO level of the first compound; The light-emitting device, wherein the first compound and the third compound are compounds having deuterium.

3. At least a light-emitting layer and a hole-transporting layer are provided between a pair of electrodes, the hole transport layer is provided in contact with the light emitting layer, the light-emitting layer includes a first compound that is a host material and a second compound that is a guest material; the hole transport layer comprises a third compound; the HOMO level of the second compound is higher than the HOMO level of the first compound; a difference between a HOMO level of the first compound and a HOMO level of the second compound is greater than 0.30 eV and less than 0.90 eV; The light-emitting device, wherein the first compound and the third compound are compounds having deuterium.

4. At least a light-emitting layer and a hole-transporting layer are provided between a pair of electrodes, the hole transport layer is provided in contact with the light emitting layer, the light-emitting layer includes a first compound that is a host material and a second compound that is a guest material; the hole transport layer comprises a third compound; The first compound has an electron mobility of 1×10 when the square root of the electric field strength [V / cm] is 600. －７ cm ２ / Vs or more, The light-emitting device, wherein the first compound and the third compound are compounds having deuterium.

5. at least a light-emitting layer, a hole transport layer, a first electron transport layer, and a second electron transport layer are disposed between a pair of electrodes; the hole transport layer is provided in contact with the light emitting layer, the light-emitting layer includes a first compound that is a host material and a second compound that is a guest material; the hole transport layer comprises a third compound; the first electron transport layer is located between the light-emitting layer and the second electron transport layer; the first electron transport layer contains a compound having a diazine skeleton or a triazine skeleton, the second electron transport layer contains a compound having a phenanthroline skeleton, The light-emitting device, wherein the first compound and the third compound are compounds having deuterium.

6. In any one of claims 1 to 5, The first compound is a compound consisting only of carbon and hydrogen.

7. In any one of claims 1 to 5, The light-emitting device, wherein the first compound is a compound having an anthracene skeleton.

8. In any one of claims 1 to 5, The first compound is a compound consisting of only carbon and hydrogen and having an anthracene skeleton.

9. At least a light-emitting layer and a hole-transporting layer are provided between a pair of electrodes, the hole transport layer is provided in contact with the light emitting layer, the light-emitting layer includes a first compound that is a host material and a second compound that is a guest material; the hole transport layer comprises a third compound; the first compound is a compound consisting only of carbon and hydrogen, The light-emitting device, wherein the first compound and the third compound are compounds having deuterium.

10. In claim 9, The light-emitting device, wherein the first compound is a compound having an anthracene skeleton.

11. In any one of claims 1 to 5, 9 and 10, T of the first compound １ T of the third compound １ A light-emitting device with a large level.

12. In any one of claims 1 to 5, 9 and 10, The third compound is a compound having only one triarylamine skeleton in its molecular structure.

13. In any one of claims 1 to 5, 9 and 10, A light-emitting device wherein the third compound is a compound different from the compound contained in the light-emitting layer.

14. In any one of claims 1 to 5, 9 and 10, The light emitting device wherein the second compound is a fluorescent compound.

15. In any one of claims 1 to 5, 9 and 10, Further, an electron transport layer is provided between the pair of electrodes, The light-emitting device has an electron transport layer having a laminated structure of two or more layers.

16. In any one of claims 1 to 5, 9 and 10, Further, an electron transport layer is provided between the pair of electrodes, A light-emitting device wherein the electron transport layer does not include an 8-quinolinol metal complex.

17. In any one of claims 1 to 5, 9 and 10, The second compound has a molecular structure containing four or more fused heteroaromatic rings.

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