Light emitting device

Abstract

Provided is a light-emitting device having high luminous efficiency. One embodiment of the present invention is a light-emitting device including a light-emitting layer between a pair of electrodes, the light-emitting layer containing a first compound, a material having a function of converting triplet excitation energy into light emission, and a material having a function of converting singlet excitation energy into light emission, at least one of the first compound and the material having the function of converting triplet excitation energy to luminescence contains deuterium, and luminescence is obtained from the material having the function of converting singlet excitation energy to luminescence.

Description

Technical Field

[0001] One aspect of the present invention relates to an organic compound, an organic semiconductor device, a light-emitting 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 aspect of the present invention is not limited to the above technical field. One aspect of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. In addition, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. Thus, more specifically, as an example of the technical field of one aspect of the present invention disclosed in this specification, semiconductor devices, display devices, liquid crystal display devices, lighting devices, power storage devices, storage devices, imaging devices, driving methods of these devices, or manufacturing methods of these devices can be cited. Background Art

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

[0003] Since the light-emitting device is a self-luminous device, a display device using this light-emitting device for pixels has higher visibility than a liquid crystal display device and does not require a backlight. In addition, a display device using such a light-emitting device can be manufactured to be thin and light, which is also a great advantage. Moreover, a very fast response speed is also one of its characteristics.

[0004] In addition, since the light-emitting layer of such a light-emitting device can be formed continuously in a planar shape, surface light emission can be obtained. Since this is a characteristic that is difficult to obtain in point light sources typified by incandescent lamps and LEDs or line light sources typified by fluorescent lamps, the above light-emitting device also has high utilization value as a surface light source that can be used for lighting and the like.

[0005] As described above, although display devices and lighting devices using light-emitting devices are applicable to various electronic devices, research and development of light-emitting devices with better characteristics are becoming increasingly active.

[0006] Patent Document 1 discloses a light-emitting device in which a metal complex is paired with a deuterated host to slow down the decomposition mechanism that plagues the metal complex, thereby improving reliability.

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2022-132158 SUMMARY OF THE INVENTION

[0008] An object of one aspect of the present invention is to provide a light-emitting device having good characteristics. Further, an object of one aspect of the present invention is to provide a light-emitting device having good reliability. Further, an object of one aspect of the present invention is to provide a light-emitting device having a low driving voltage. Further, an object of one aspect of the present invention is to provide a light-emitting device having high reliability and a low driving voltage.

[0009] Further, an object of one aspect of the present invention is to provide a light-emitting device capable of providing a display device having good characteristics. Further, an object of one aspect of the present invention is to provide a light-emitting device capable of providing a display device having good reliability. Further, an object of one aspect of the present invention is to provide a light-emitting device capable of providing a display device having a low driving voltage. Further, an object of one aspect of the present invention is to provide a light-emitting device capable of providing a display device having a low driving voltage and good reliability.

[0010] Further, an object of one aspect of the present invention is to provide any one of an organic semiconductor device, a light-emitting device, a light-receiving device, a display device, an electronic device, and a lighting device having low power consumption. Further, an object of one aspect of the present invention is to provide any one of an electronic device and a lighting device having high reliability.

[0011] The present invention only needs to achieve any one of the above objects.

[0012] One aspect of the present invention is a light-emitting device including a light-emitting layer between a pair of electrodes, the light-emitting layer containing a first compound, a material having a function of converting triplet excitation energy into light, and a material having a function of converting singlet excitation energy into light, at least one of the first compound and the material having a function of converting triplet excitation energy into light contains deuterium, and light emission is obtained from the material having a function of converting singlet excitation energy into light.

[0013] One aspect of the present invention is a light-emitting device including a light-emitting layer between a pair of electrodes, the light-emitting layer containing a first compound, a second compound, a material having a function of converting triplet excitation energy into light, and a material having a function of converting singlet excitation energy into light, at least one of the first compound, the second compound, and the material having a function of converting triplet excitation energy into light contains deuterium, and light emission is obtained from the material having a function of converting singlet excitation energy into light.

[0014] In the above light-emitting device, the first compound includes a π-deficient heteroaromatic ring, and the second compound includes at least one of a π-excessive heteroaromatic ring and an aromatic amine skeleton.

[0015] In the above light-emitting device, the difference between the lowest triplet excitation energy level (T1 level) of the first compound and the lowest triplet excitation energy level of the second compound is 0.20 eV or less.

[0016] In the above light-emitting device, the first compound and the second compound are a combination that forms an exciplex, and the emission spectrum of the exciplex overlaps with the emission spectrum of a material having a function of converting triplet excitation energy into light emission.

[0017] In any of the above inventions, the first compound contains deuterium, and the phosphorescence emission lifetime or delayed fluorescence lifetime of the first compound at 77K is longer than the phosphorescence emission lifetime or delayed fluorescence lifetime of the non-deuterated form of the first compound at 77K.

[0018] In any of the above inventions, the second compound contains deuterium, and the phosphorescence emission lifetime or delayed fluorescence lifetime of the second compound at 77K is longer than the phosphorescence emission lifetime or delayed fluorescence lifetime of the non-deuterated form of the second compound at 77K.

[0019] In any of the above inventions, the material having a function of converting triplet excitation energy into light emission contains deuterium, and the phosphorescence emission lifetime or delayed fluorescence lifetime of the material having a function of converting triplet excitation energy into light emission at room temperature is longer than the phosphorescence emission lifetime or delayed fluorescence lifetime of the non-deuterated form of the material having a function of converting triplet excitation energy into light emission at room temperature.

[0020] In any of the above inventions, the material having a function of converting triplet excitation energy into light emission is a phosphorescent light-emitting substance.

[0021] In any of the above inventions, the material having a function of converting triplet excitation energy into light emission is a TADF material.

[0022] In any of the above inventions, the material having a function of converting singlet excitation energy into light emission is a fluorescent light-emitting substance.

[0023] In any of the above inventions, the material having a function of converting singlet excitation energy into light emission is a fluorescent light-emitting substance including a lumophore and a protecting group, the lumophore is a fused aromatic ring or a fused heteroaromatic ring, and the protecting group includes any one of an alkyl group having 1 or more and 10 or less carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 or more and 10 or less carbon atoms, and a trialkylsilyl group having 3 or more and 10 or less carbon atoms. Additionally, the protecting group is a light-emitting device containing deuterium.

[0024] In any of the above inventions, the material having a function of converting singlet excitation energy into light emission is a TADF material.

[0025] In addition, another aspect of the present invention is a display device including any of the above-described light-emitting devices.

[0026] In addition, another aspect of the present invention is an electronic device including: any of the above-described light-emitting devices; a sensor, an operation button, a speaker, or a microphone.

[0027] In addition, another aspect of the present invention is a lighting device including: any of the above-described light-emitting devices; and a housing.

[0028] One aspect of the present invention can provide a light-emitting device with high luminous efficiency. In addition, one aspect of the present invention can provide a light-emitting device with good reliability. Further, any one of a display device, an electronic device, and a lighting device with low power consumption can be provided. Further, any one of a display device, an electronic device, and a lighting device with high reliability can be provided.

[0029] Note that the description of these effects does not preclude the existence of other effects. Note that one aspect of the present invention does not necessarily have all of the above effects. Note that effects other than the above can be known and extracted from the descriptions in the specification, drawings, claims, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figures 1A to 1C is a diagram illustrating the structure of a light-emitting device according to an embodiment; Figures 2A to 2D is a schematic diagram of energy transfer between compounds in a light-emitting layer; Figure 3 is a diagram illustrating a method for calculating the emission lifetime; Figures 4A to 4F is a diagram illustrating the structure of a light-emitting device according to an embodiment; Figure 5A and Figure 5B are a top view and a cross-sectional view of a light-emitting device; Figures 6A to 6D is a diagram showing a light-emitting device; Figures 7A to 7E is a cross-sectional view showing an example of a method for manufacturing a light-emitting device; Figure 8A and Figure 8B is a cross-sectional view showing an example of a method for manufacturing a light-emitting device; Figures 9A to 9D is a cross-sectional view showing an example of a method for manufacturing a light-emitting device; Figures 10A to 10C is a cross-sectional view showing an example of a method for manufacturing a light-emitting device; Figures 11A to 11C is a cross-sectional view showing an example of a method for manufacturing a light-emitting device; Figures 12A to 12Cis a cross-sectional view showing an example of a method for manufacturing a light-emitting device; Figures 13A to 13G is a top view showing an example of the structure of a pixel; Figures 14A to 14I is a top view showing an example of the structure of a pixel; Figure 15A and Figure 15B is a perspective view showing an example of the structure of a display module; Figure 16A and Figure 16B is a cross-sectional view showing an example of the structure of a light-emitting device; Figure 17 is a perspective view showing an example of the structure of a light-emitting device; Figure 18A is a cross-sectional view showing an example of the structure of a light-emitting device, Figure 18B and Figure 18C is a cross-sectional view showing an example of the structure of a transistor; Figure 19 is a cross-sectional view showing an example of the structure of a light-emitting device; Figures 20A to 20C is a cross-sectional view showing an example of the structure of a light-emitting device; Figures 21A to 21D is a cross-sectional view showing an example of the structure of a light-emitting device; Figures 22A to 22C is a cross-sectional view showing an example of the structure of a light-emitting device; Figures 23A to 23D is a diagram showing an example of an electronic device; Figures 24A to 24F is a diagram showing an example of an electronic device; Figures 25A to 25G is a diagram showing an example of an electronic device; Figure 26 is a diagram for explaining the structure of a light-emitting device according to an embodiment; Figure 27 is a diagram showing the luminance-current density characteristics of light-emitting devices 1A to 1D; Figure 28 is a diagram showing the luminance-voltage characteristics of light-emitting devices 1A to 1D; Figure 29 is a diagram showing the current efficiency-luminance characteristics of light-emitting devices 1A to 1D; Figure 30 is a diagram showing the current density-voltage characteristics of light-emitting devices 1A to 1D; Figure 31 is a diagram showing the external quantum efficiency-luminance characteristics of light-emitting devices 1A to 1D; Figure 32is a diagram showing the electroluminescence spectra of light-emitting devices 1A to 1D; Figure 33 is a diagram showing the luminance-current density characteristics of light-emitting devices 1E to 1H; Figure 34 is a diagram showing the luminance-voltage characteristics of light-emitting devices 1E to 1H; Figure 35 is a diagram showing the current efficiency-luminance characteristics of light-emitting devices 1E to 1H; Figure 36 is a diagram showing the current density-voltage characteristics of light-emitting devices 1E to 1H; Figure 37 is a diagram showing the external quantum efficiency-luminance characteristics of light-emitting devices 1E to 1H; Figure 38 is a diagram showing the electroluminescence spectra of light-emitting devices 1E to 1H; Figure 39 is a diagram showing the change in luminance of light-emitting devices 1A to 1D with respect to the driving time; Figure 40 is a diagram showing the change in luminance of light-emitting devices 1E to 1H with respect to the driving time; Figure 41 is a diagram showing the change in luminance of light-emitting devices 1A, 1D, 1E, 1H with respect to the driving time; Figure 42 is a diagram showing 8mpTP-4mDBtPBfpm-d 13 of the single film, βNCCP-d 26 of the single film and the emission spectra of the hybrid film; Figure 43A is a diagram showing the absorption spectrum and emission spectrum of Ir(ppy)2(mbfpypy), Figure 43B is a diagram showing the emission spectrum of Ir(ppy)2(mbfpypy) and 8mpTP-4mDBtPBfpm-d 13 and βNCCP-d 26 of the hybrid film; Figure 44A is a diagram showing the absorption spectrum and emission spectrum of Ir(ppy)2(mbfpypy-d3), Figure 44B is a diagram showing the emission spectrum of Ir(ppy)2(mbfpypy-d3) and 8mpTP-4mDBtPBfpm-d 13 and βNCCP-d 26 of the hybrid film; Figure 45A andFigure 45B is a diagram showing a method for calculating the lowest triplet excitation energy; Figure 46 is a diagram showing the luminance-current density characteristics of light-emitting devices 2A to 2C; Figure 47 is a diagram showing the luminance-voltage characteristics of light-emitting devices 2A to 2C; Figure 48 is a diagram showing the current efficiency-luminance characteristics of light-emitting devices 2A to 2C; Figure 49 is a diagram showing the current density-voltage characteristics of light-emitting devices 2A to 2C; Figure 50 is a diagram showing the blue index-luminance characteristics of light-emitting devices 2A to 2C; Figure 51 is a diagram showing the external quantum efficiency-luminance characteristics of light-emitting devices 2A to 2C; Figure 52 is a diagram showing the electroluminescence spectra of light-emitting devices 2A to 2C; Figure 53 is a diagram showing the luminance-current density characteristics of light-emitting devices 3A to 3C; Figure 54 is a diagram showing the luminance-voltage characteristics of light-emitting devices 3A to 3C; Figure 55 is a diagram showing the current efficiency-luminance characteristics of light-emitting devices 3A to 3C; Figure 56 is a diagram showing the current density-voltage characteristics of light-emitting devices 3A to 3C; Figure 57 is a diagram showing the blue index-luminance characteristics of light-emitting devices 3A to 3C; Figure 58 is a diagram showing the external quantum efficiency-luminance characteristics of light-emitting devices 3A to 3C; Figure 59 is a diagram showing the electroluminescence spectra of light-emitting devices 3A to 3C; Figure 60 is a diagram showing the luminance change of light-emitting devices 2A to 2C with respect to the driving time; Figure 61 is a diagram showing the luminance change of light-emitting devices 3A to 3C with respect to the driving time; Figure 62 is a diagram showing the single film of SiTrzCz2-d 16 of PSiCzCz-d 15Graphs of the emission spectra of single films and hybrid films; Figure 63A Graph showing the absorption and emission spectra of PtON-TBBI, Figure 63B Graph showing the emission spectrum of PtON-TBBI and the emission spectra of the hybrid films of SiTrzCz2-d 16 and PSiCzCz-d 15 ; Figure 64A Graph showing the absorption and emission spectra of Pt(mmtBubOcz35dm4ppy-d6), Figure 64B Graph showing the emission spectrum of Pt(mmtBubOcz35dm4ppy-d6) and the emission spectra of the hybrid films of SiTrzCz2-d 16 and PSiCzCz-d 15 ; Detailed implementation mode

[0031] Implementation mode 1 In this implementation mode, a light-emitting device of one aspect of the present invention is described.

[0032] 〔Structural example of the light-emitting device〕 First, with reference to Figures 1A to 1C the structure of a light-emitting device of one aspect of the present invention is described.

[0033] Figure 1A is a cross-sectional schematic view of a light-emitting device 10 of one aspect of the present invention.

[0034] The light-emitting device 10 includes a pair of electrodes (a first electrode 101 and a second electrode 102), and includes an organic compound layer 103 disposed between the pair of electrodes. The organic compound layer 103 includes at least a light-emitting layer 113. In addition, the organic compound layer 103 is also referred to as an EL layer.

[0035] In addition, Figure 1A the organic compound layer 103 shown in addition to the light-emitting layer 113 also 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.

[0036] Note that although in this implementation mode the first electrode 101 of the pair of electrodes is described as an anode and the second electrode 102 as a cathode, the structure of the light-emitting device 10 is not limited thereto. That is, the first electrode 101 may be a cathode and the second electrode 102 an anode, such that the stacking order of the layers between the electrodes is reversed. That is, 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 may be stacked in order from the anode side.

[0037] Note that the structure of the organic compound layer 103 is not limited to Figure 1A the structure shown. As long as it includes at least one selected from the hole injection layer 111, the hole transport layer 112, the electron transport layer 114, and the electron injection layer 115. Alternatively, the organic compound layer 103 may also include a functional layer having the following functions: capable of reducing the injection barrier of holes or electrons; capable of improving the transportability of holes or electrons; capable of hindering the transportability of holes or electrons; or capable of suppressing the quenching phenomenon caused by the electrode, etc. Note that the functional layer may be a single layer or a structure in which multiple layers are stacked.

[0038] Figure 1B and Figure 1C is a cross-sectional schematic diagram showing Figure 1A an example of the light-emitting layer 113 shown. Figure 1B The light-emitting layer 113 shown contains compound 131, compound 132, compound 133, and compound 134. Figure 1C The light-emitting layer 113 shown contains compound 131, compound 133, and compound 134. Note that both compound 131 and compound 132 are substances used as host materials. Compound 133 is a material having the function of converting triplet excitation energy into light emission. Compound 134 is a material having the function of converting singlet excitation energy into light emission. In addition, the light-emitting layer 113 can obtain light emission from compound 134 which is a material having the function of converting singlet excitation energy into light emission.

[0039] <Example 1 of the structure of the light-emitting layer> First, an example of the specific structure of the light-emitting layer 113 will be described. In this structural example, as shown in Figure 1B the light-emitting layer 113 contains compound 131, compound 132, compound 133, and compound 134. In addition, in this structural example, the following situation will be described: compound 133 which is a material having the function of converting triplet excitation energy into light emission is a phosphorescent light-emitting substance and compound 134 which is a material having the function of converting singlet excitation energy into light emission is a fluorescent light-emitting substance. Figure 2A Shows an example related to the energy levels in the light-emitting layer 113 of this structural example. The following notations and symbols in Figure 2A will be given. ·Comp(131): Compound 131 ·Comp(132): Compound 132 ·Comp(133): Compound 133 ·Guest(134): Compound 134 ·S C1 : The S1 energy level of compound 131 ·T C1: T1 energy level of Compound 131 ·S C2 : S1 energy level of Compound 132 ·T C2 : T1 energy level of Compound 132 ·S E : S1 energy level of exciplex ·T E : T1 energy level of exciplex ·T C3 : T1 energy level of Compound 133 ·S G : S1 energy level of Compound 134 ·T G : T1 energy level of Compound 134

[0040] The combination of Compound 131 and Compound 132 used as host materials is preferably a combination capable of forming an exciplex. More preferably, one is a hole-transporting material and the other is an electron-transporting material. In this case, a donor-acceptor type exciplex is easily formed, and the exciplex can be efficiently formed. In addition, when the combination of Compound 131 and Compound 132 is a combination of a compound having hole-transporting properties and a compound having electron-transporting properties, the carrier balance can be easily controlled according to the mixing ratio. Specifically, the mixing ratio is preferably in the following range: the compound having hole-transporting properties: the compound having electron-transporting properties is in the range of 1:9 to 9:1 (weight ratio). In addition, by having this structure, the carrier balance can be easily controlled, and thus the carrier recombination region can also be easily controlled.

[0041] As the hole-transporting material, more specifically, a compound having one or both of a π-electron-rich heteroaromatic ring and an aromatic amine skeleton can be cited. As the electron-transporting material, more specifically, a compound having a π-electron-deficient heteroaromatic ring can be cited.

[0042] In addition, as a combination of host materials for efficiently forming an exciplex, preferably, in Compound 131 and Compound 132, the HOMO energy level of one is higher than that of the other, and the LUMO energy level of one is higher than that of the other. In addition, the HOMO energy level of Compound 131 may be equal to the HOMO energy level of Compound 132, or the LUMO energy level of Compound 131 may be equal to the LUMO energy level of Compound 132.

[0043] Note that the LUMO energy level and HOMO energy level of a compound can be obtained from the electrochemical properties (reduction potential and oxidation potential) of the compound measured by cyclic voltammetry (CV) measurement or the like.

[0044] AsFigure 2A As shown, the S1 energy level (S E ) of the exciplex formed by Compound 131 and Compound 132 and the T1 energy level (T E ) of the exciplex become adjacent energy levels (refer to Path A1 in Figure 2A ).

[0045] The excitation energy levels (S E and T E ) of the exciplex formed by Compound 131 and Compound 132 are lower than the S1 energy levels (S C1 and S C2 ) of the respective substances forming the exciplex (Compound 131 and Compound 132). Therefore, an excited state can be formed with a lower excitation energy. As a result, the driving voltage of the light-emitting device can be reduced. Note that the formation of the exciplex can be confirmed, for example, by comparing the emission spectra of Compound 131, the emission spectrum of Compound 132, and the emission spectrum of a mixed film formed by mixing Compound 131 and Compound 132. When a phenomenon that the emission spectrum of the mixed film shifts to the long-wavelength side (or has a new peak on the long-wavelength side) compared to the emission spectra of the respective materials is observed, it indicates the formation of an exciplex.

[0046] Note that the energy level relationship between Compound 131 and Compound 132 is not limited to Figure 2A . That is, the singlet excitation energy level (S C1 ) of Compound 131 can also be higher than or lower than the singlet excitation energy level (S C2 ) of Compound 132. In addition, the triplet excitation energy level (T C1 ) of Compound 131 can also be higher than or lower than the triplet excitation energy level (T C2 ) of Compound 132.

[0047] Since Compound 133 is a phosphorescent light-emitting substance, both the singlet excitation energy and the triplet excitation energy rapidly transfer from the S1 energy level (S E ) of the exciplex formed by Compound 131 and Compound 132 and the T1 energy level (T E ) of the exciplex to the T1 energy level (T C3 ) of Compound 133 (Path A2). At this time, it is preferable to satisfy T E ≥T C3 . In Path A2, the exciplex is used as an energy donor and Compound 133 is used as an energy acceptor.

[0048] In addition, the triplet excitation energy possessed by Compound 133 is converted into the singlet excitation energy of Compound 134, which is a fluorescent light-emitting substance (Path A3). At this time, as Figure 2A shown, when T E ≥TC3 ≥S G In the case of ≥S, energy is efficiently transferred from Compound 133 to Compound 134, so it is preferred. More specifically, it is preferred to draw a tangent line at the tail on the short-wavelength side of the phosphorescence spectrum of Compound 133, and set the energy of the wavelength of this extrapolated line to T C3 and set the energy of the wavelength at the absorption edge of the absorption spectrum of Compound 134 to S G At this time, T C3 ≥S G is satisfied. In Path A3, Compound 133 is used as an energy donor and Compound 134 is used as an energy acceptor.

[0049] However, in the light-emitting layer 113 of the light-emitting device shown in this structural example, in addition to the above, there may be a path in which the triplet excitation energy of Compound 133 is transferred to the T1 energy level of Compound 134 ( Figure 2A Path A4 in ). In the case where this energy transfer (Path A4) occurs, the triplet excitation energy of Compound 134 as a fluorescent light-emitting substance does not contribute to light emission, thereby reducing the light-emitting efficiency of the light-emitting device.

[0050] Generally speaking, as the intermolecular energy transfer mechanism, the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange interaction) are known. When the distance between the compound as an energy donor and the compound as an energy acceptor is 1 nm or less, the Dexter mechanism is dominant. Thus, when the concentration of the compound as an energy acceptor increases, the Dexter mechanism is likely to occur. Therefore, as in this structural example, when Compound 134 as an energy acceptor is a fluorescent material with a low triplet excitation energy level and its concentration increases, the triplet excitation energy of Compound 133 as an energy donor is mainly transferred through Path A4 based on the Dexter mechanism and then exhibits non-radiative deactivation. Therefore, in order to suppress the energy transfer through Path A4, the distance between Compound 133 and Compound 134 is increased to an extent that does not easily cause energy transfer based on the Dexter mechanism.

[0051] In addition, the T1 energy level (T G ) of Compound 134 as an energy acceptor mostly originates from the energy level of the lumophore contained in Compound 134. Therefore, in order to suppress the energy transfer through Path A4 in the light-emitting layer 113, it is more preferred to increase the distance between Compound 133 and the lumophore contained in Compound 134.

[0052] As a method of increasing the distance between a light emitter contained in an energy donor and an energy acceptor, a method of reducing the concentration of the energy acceptor in a mixed film of these compounds is known. However, when the concentration of the energy acceptor is reduced, not only the Dexter mechanism-based energy transfer from the energy donor to the energy acceptor but also the Förster mechanism-based energy transfer is suppressed. In this case, since the path A3 is based on the Förster mechanism, problems such as a decrease in the luminous efficiency or reliability of the light-emitting device occur.

[0053] Therefore, the compound 134 as an energy acceptor is preferably a compound that contains a light emitter as a part of its structure and a protecting group having a function of increasing the distance between the light emitter and other energy donors. In addition, the Dexter mechanism predominates when the distance between the energy donor and the energy acceptor is 1 nm or less, and the Förster mechanism predominates when the distance between the energy donor and the energy acceptor is more than 1 nm and 10 nm or less. Therefore, the protecting group is preferably a bulky substituent that extends within a range of 1 nm or more and 10 nm or less from the light emitter. By using such a compound as the compound 134, even when the concentration of the compound 134 is increased, the energy transfer rate based on the Förster mechanism can be increased while suppressing the energy transfer based on the Dexter mechanism. That is, although the transfer of the triplet excitation energy from the compound 133 to the S1 energy level (S G ) of the compound 134 (path A3) easily occurs, the transfer of the triplet excitation energy from the compound 133 to the T1 energy level (T G ) of the compound 134 (path A4: energy transfer based on the Dexter mechanism) is suppressed, and thus the luminous efficiency of the light-emitting device can be increased while suppressing the decrease in the luminous efficiency of the energy transfer through the path A4.

[0054] In addition, in this structural example, by increasing the concentration of the compound 134 as an energy acceptor, the energy transfer rate based on the Förster mechanism can be increased while suppressing the energy transfer based on the Dexter mechanism. By increasing the energy transfer rate based on the Förster mechanism, the excitation lifetime of the energy acceptor in the light-emitting layer becomes shorter, and thus the reliability of the light-emitting device can be improved. Specifically, the concentration of the compound 134 in the light-emitting layer 113 is preferably 2 wt% or more and 50 wt% or less, more preferably 5 wt% or more and 30 wt% or less, and further preferably 5 wt% or more and 20 wt% or less with respect to the compound 133 as an energy donor.

[0055] In this specification, the paths of the above paths A1 and A2 are also referred to as ExTET (Exciplex-Triplet Energy Transfer). In other words, in the light-emitting layer 113 of this specification, the supply of excitation energy from the exciplex to the compound 133 is generated.

[0056] <Example 2 of the structure of the light-emitting layer> Next, Example 2 of the specific structure of the light-emitting layer 113 will be described. In this structural example, as Figure 1B shown, the light-emitting layer 113 includes Compound 131, Compound 132, Compound 133, and Compound 134. In addition, in this structural example, the following situation is described: Compound 133, which is a material having the function of converting triplet excitation energy into light emission, is a phosphorescent light-emitting substance, and Compound 134, which is a material having the function of converting singlet excitation energy into light emission, is a thermally activated delayed fluorescence (TADF: Thermally Activated Delayed Fluorescence) material. The TADF material is a material having the function of converting both singlet excitation energy and triplet excitation energy into light emission. Figure 2B An example related to the energy levels in the light-emitting layer 113 of this structural example is shown. Note that Figure 2B the marks, symbols, Path A1, and Path A2 in Figure 2A are the same, so their descriptions are omitted.

[0057] After passing through Figure 2B the triplet excitation energy transferred from the exciplex formed by Compound 131 and Compound 132 to Compound 133 through the shown Path A2 is converted into the singlet excitation energy of Compound 134, which is a TADF material (Path A5). At this time, as Figure 2B shown, in the case of T E ≥ T C3 ≥ S G it is preferable because the energy is efficiently transferred from Compound 133 to Compound 134. More specifically, it is preferable to draw a tangent line at the short-wavelength side tail of the phosphorescence spectrum of Compound 133, set the energy of the wavelength of this extrapolated line as T C3 , set the energy of the wavelength at the absorption edge of the absorption spectrum of Compound 134 as S G , and at this time, T C3 ≥ S G is satisfied.

[0058] In addition, in the light-emitting layer 113 of the light-emitting device shown in this structural example, in addition to the above, the triplet excitation energy of Compound 133 is transferred to the T1 energy level of Compound 134 ( Figure 2B Path A6 in Figure 2BIn the path A7), thermally activated delayed fluorescence is presented. Therefore, Compound 134 can efficiently emit light from the singlet excited state, thereby improving the light emission efficiency of the light-emitting device. In Path A5 and Path A6, Compound 133 is used as an energy donor and Compound 134 is used as an energy acceptor.

[0059] In Structural Example 1 and Structural Example 2, the structure of the light-emitting layer 113 including four compounds (Compound 131, Compound 132, Compound 133, and Compound 134) is shown, but one embodiment of the present invention is not limited thereto. In Structural Example 3 and Structural Example 4 described below, the structure of the light-emitting layer 113 including three compounds (Compound 131, Compound 133, and Compound 134) is described.

[0060] <Structural Example 3 of the Light-Emitting Layer> A specific Structural Example 3 of the light-emitting layer 113 is described. In this structural example, as Figure 1C shown, the light-emitting layer 113 includes Compound 131, Compound 133, and Compound 134. In addition, in this structural example, the following case is described: Compound 133 as a material having a function of converting triplet excitation energy into light emission is a phosphorescent light-emitting material, and Compound 134 as a material having a function of converting singlet excitation energy into light emission is a fluorescent light-emitting material. Figure 2C An example related to the energy levels in the light-emitting layer 113 of this structural example is shown. The following notations and symbols in Figure 2C are cited. ·Comp(131): Compound 131 ·Comp(133): Compound 133 ·Guest(134): Compound 134 ·S C1 : S1 energy level of Compound 131 ·T C1 : T1 energy level of Compound 131 ·T C3 : T1 energy level of Compound 133 ·T G : T1 energy level of Compound 134 ·S G : S1 energy level of Compound 134

[0061] In this structural example, since recombination of carriers mainly occurs in Compound 131, singlet excitons and triplet excitons are generated. By selecting a phosphorescent light-emitting material having a relationship of T C3 ≤T C1 as Compound 133, both the singlet excitation energy and the triplet excitation energy generated in Compound 131 can be transferred to the T of Compound 133 C3Energy level ( Figure 2C Path A in 18 ). Note that some of the carriers may recombine in Compound 133.

[0062] The phosphorescent luminescent material used in the above structure preferably contains heavy atoms such as Ir, Pt, Os, Ru, Pd, etc. When the phosphorescent luminescent material is used as Compound 133, the energy transfer from the triplet excited state of the energy donor to the singlet excited state of the guest material (energy acceptor) is an allowed transition, so it is preferred. Therefore, the triplet excitation energy of Compound 133 can pass through Path A 19 and be transferred to the S1 energy level of the guest material (S G ). In Path A 19 , Compound 133 is used as the energy donor and Compound 134 is used as the energy acceptor. At this time, when T C3 ≥S G is satisfied, the excitation energy of Compound 133 is efficiently transferred to the singlet excited state of Compound 134 as the guest material, so it is preferred. Specifically, it is preferred to draw a tangent line at the tail on the short wavelength side of the phosphorescence spectrum of Compound 133, set the energy of the wavelength of this extrapolated line as T C3 , set the energy of the wavelength at the absorption edge of the absorption spectrum of Compound 134 as S G , and at this time T C3 ≥S G is satisfied. However, in the light-emitting layer 113 of the light-emitting device shown in this structural example, in addition to the above, there is also a path for the triplet excitation energy of Compound 133 to be transferred to the T1 energy level of Compound 134 ( Figure 2C Path A in 20 ), and there will be competition between the two. When this energy transfer (Path A 20 ) occurs, the triplet excitation energy of Compound 134 as the fluorescent luminescent material does not contribute to light emission, resulting in a decrease in the light emission efficiency of the light-emitting device.

[0063] To suppress this energy transfer (Path A 20 ), as explained in Structural Example 1 above, it is important that the distance between Compound 133 and Compound 134, that is, the distance between the luminophores contained in Compound 133 and Compound 134, is long.

[0064] A part of the structure of the compound according to one embodiment of the present invention contains a light emitter and a protecting group. When this compound is used as an energy acceptor in the light-emitting layer 113, the protecting group has a function of increasing the distance between other energy donors and the light emitter. Therefore, when the compound according to one embodiment of the present invention is used as the compound 134 in this structure, even if the concentration of the compound 134 increases, the distance between the compound 133 and the compound 134 can be increased, and the energy transfer rate based on the Förster mechanism can be increased while suppressing the energy transfer based on the Dexter mechanism. Therefore, by using the compound according to one embodiment of the present invention as the compound 134, the transfer of the triplet excitation energy from the compound 133 to the S1 energy level (S G ) of the compound 134 (path A 19 ) easily occurs. On the other hand, the transfer of the triplet excitation energy from the compound 133 to the T1 energy level (T G ) of the compound 134 (path A 20 : energy transfer based on the Dexter mechanism) is suppressed. As a result, the decrease in the light-emitting efficiency accompanying the energy transfer along path A 20 can be suppressed while increasing the light-emitting efficiency of the light-emitting device. In addition, the reliability of the light-emitting device can be improved.

[0065] <Example 4 of the structure of the light-emitting layer> In this structural example, the light-emitting layer 113 in the light-emitting device contains the compound 131, the compound 134, and the compound 133 as shown in Figure 1C . Note that it is shown that the compound 133, which is a material having a function of converting triplet excitation energy into light, is a TADF material, and the compound 134, which is a material having a function of converting singlet excitation energy into light, is a fluorescent light-emitting substance. Figure 2D An example related to the energy levels in the light-emitting layer 113 of this structural example is shown. Note that Figure 2D the marks and symbols in Figure 2C are the same, and the following other marks and symbols are shown. ·S C3 : S1 energy level of the compound 133

[0066] In this structural example, since carrier recombination mainly occurs in the compound 131, singlet excitons and triplet excitons are generated. By selecting a TADF material having a relationship of S C3 ≤S C1 and T C3 ≤T C1 as the compound 133, both the singlet excitation energy and the triplet excitation energy generated in the compound 131 can be transferred to the S C3 and T C3 energy levels of the compound 133 (path A in Figure 2D )21 )。Note that some of the carriers may recombine in Compound 133.

[0067] Since Compound 133 is a TADF material, it has the function of converting triplet excitation energy into singlet excitation energy through upconversion ( Figure 2D Path A in 22 ). In addition, the singlet excitation energy possessed by Compound 133 can be rapidly transferred to Compound 134 ( Figure 2D Path A in 23 ). At this time, it is preferable to satisfy S C3 ≥S G . More specifically, preferably, a tangent line is drawn at the tail on the short-wavelength side of the fluorescence spectrum of Compound 133, and the energy of the wavelength of this extrapolated line is set as S C3 , and the energy of the wavelength at the absorption edge of the absorption spectrum of Compound 134 is set as S G , and at this time, S C3 ≥S G is satisfied.

[0068] Therefore, in the light-emitting layer 113 of the light-emitting device shown in this structural example, by passing through Figure 2D Path A in 21 , Path A 22 and Path A 23 's paths, the triplet excitation energy generated in Compound 133 can be converted into the fluorescence emission of Compound 134. In Path A 23 , Compound 133 is used as an energy donor and Compound 134 is used as an energy acceptor. However, in the light-emitting layer 113 of the light-emitting device shown in this structural example, in addition to the above, there is also a path for the triplet excitation energy of Compound 133 to transfer to the T1 energy level of Compound 134 ( Figure 2D Path A in 24 ), and there will be competition between the two. In the case where this energy transfer (Path A 24 ) occurs, the triplet excitation energy of Compound 134 as a fluorescent light-emitting substance does not contribute to light emission, thereby reducing the light-emitting efficiency of the light-emitting device.

[0069] To suppress this energy transfer (Path A 24 ), as explained in Structural Example 1 above, it is important that the distance between Compound 133 and Compound 134, that is, the distance between Compound 133 and the lumophore contained in Compound 134, is long.

[0070] A part of the structure of the compound according to one embodiment of the present invention contains a light emitter and a protecting group. When the compound is used as an energy acceptor in the light-emitting layer 113, the protecting group has a function of increasing the distance between other energy donors and the light emitter. Therefore, when the compound according to one embodiment of the present invention is used as the compound 134 in this structure, even if the concentration of the compound 134 increases, the distance between the compound 133 and the compound 134 can be increased, and the energy transfer rate based on the Förster mechanism can be increased while suppressing the energy transfer based on the Dexter mechanism. Therefore, by using the compound according to one embodiment of the present invention as the compound 134, the transfer of the triplet excitation energy from the compound 133 to the S1 energy level (S G ) of the compound 134 (path A 23 ) is likely to occur. On the other hand, the transfer of the triplet excitation energy from the compound 133 to the T1 energy level (T G ) of the compound 134 (path A 24 : energy transfer based on the Dexter mechanism) is suppressed. Thus, it is possible to improve the luminous efficiency of the light-emitting device while suppressing the decrease in the luminous efficiency accompanying the energy transfer of path A 24 . In addition, the reliability of the light-emitting device can be improved.

[0071] In path A2 of Structure Example 1 and Structure Example 2 of the above-described light-emitting layer structure, the exciplex formed by the compound 131 and the compound 132 is used as an energy donor. In path A3 of Structure Example 1 and paths A5 and A6 of Structure Example 2, the compound 133 is used as an energy donor, whereby a highly efficient light-emitting device can be obtained. In addition, in path A 18 of Structure Example 3 of the light-emitting layer, the compound 131 is used as an energy donor, and in path A 19 , the compound 133 is used as an energy donor, whereby a highly efficient light-emitting device can be obtained. In addition, in path A 21 of Structure Example 4 of the light-emitting layer, the compound 131 is used as an energy donor, and in path A 23 , the compound 133 is used as an energy donor, whereby a highly efficient light-emitting device can be obtained.

[0072] Here, preferably, among Compound 131, Compound 132, and Compound 133 used as energy donors in the light-emitting layer, at least one compound, preferably any two compounds, and most preferably all compounds contain deuterium. This is because: the bond dissociation energy of the bond between carbon and deuterium is greater than that of the bond between carbon and protium, which is stable and not easily broken. Therefore, the compound containing deuterium is more stable and less likely to deteriorate compared to the non-deuterated form. When at least one compound, preferably any two compounds, and most preferably all compounds among Compound 131, Compound 132, and Compound 133 contain deuterium, the stability of the compound can be improved, and the deterioration of the energy donor can be suppressed. Therefore, the decrease in the energy transfer efficiency to Compound 134 over time can be suppressed, and thus the reliability of the light-emitting device can be improved.

[0073] Note that when Compound 131, Compound 132, and Compound 133 are compounds containing deuterium, each compound may contain both hydrogen and deuterium, or may not contain hydrogen and only contain deuterium.

[0074] In addition, in Compound 131 and Compound 132, the entire molecule may be deuterated, but preferably, the group or skeleton with the lowest triplet excitation energy level is locally deuterated. Thus, compared with the case where the entire molecule is deuterated, Compound 131 and Compound 132 can be obtained at a lower cost.

[0075] In addition, in Compound 133, the entire molecule may be deuterated, but preferably, the group that is more easily cleaved is deuterated. For example, when using an organometallic complex in which at least one of the ligands as Compound 133 includes an alkyl group such as a methyl group, the alkyl group is preferably deuterated. Thus, compared with deuterating the entire molecule, Compound 133 can be obtained at a lower cost and the reliability of the light-emitting device can be improved.

[0076] In this specification, "containing deuterium" means that the proportion of deuterium in the hydrogen and deuterium contained in the compound is significantly higher than the natural abundance ratio of deuterium, specifically 500 times or more. A "deuterated compound" refers to a compound in which the proportion of deuterium in the hydrogen and deuterium contained in the compound is significantly higher than the natural abundance ratio of deuterium, specifically 500 times or more. In addition, this ratio is the average value of multiple target compounds present in a certain region, rather than the ratio relative to one molecule.

[0077] More preferably, in the above structure, Compound 134 used as an energy acceptor in the light-emitting layer also contains deuterium. As described above, compared with the non-deuterated form, the compound containing deuterium is more stable and less likely to deteriorate. Therefore, when Compound 134 contains deuterium, the stability of the compound can be improved. Therefore, when Compound 134 contains deuterium, the decrease in the luminous efficiency of the light-emitting device over time can be suppressed, and thus the reliability of the light-emitting device can be improved.

[0078] In compound 134, the entire molecule can also be deuterated. However, when using a fluorescent light-emitting substance containing deuterium as compound 134, it is more preferable to use a fluorescent light-emitting substance in which the protecting group is deuterated. Compared with deuterating the entire molecule, compound 134 can be obtained at a lower cost and the reliability of the light-emitting device can be improved. In particular, when the protecting group is an alkyl group having 3 or more and 10 or less carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 or more and 10 or less carbon atoms, or a trialkylsilyl group having 3 or more and 10 or less carbon atoms, deterioration starting from the hydrogen of these groups can be suppressed.

[0079] Another reason why the reliability of the light-emitting device can be improved when at least one of compound 131, compound 132, and compound 133 used as an energy donor in the light-emitting layer, preferably any two compounds, and most preferably all compounds contain deuterium is that: since the phosphorescence lifetime or delayed fluorescence lifetime of the deuterated compound is longer than the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated compound, the energy transfer efficiency is improved. This is because: compared with the intramolecular vibration of the non-deuterated compound, the intramolecular vibration in the lowest triplet excited state (T1 state) of the deuterated compound is suppressed, and thus the non-radiative transfer from the T1 state to a more stable state is suppressed.

[0080] Energy transfer efficiency from energy donor to energy acceptor Is represented by the following formula (1). According to this formula, in order to improve the energy transfer efficiency Increase the rate constant k of energy transfer h*→g To make other competing rate constants k r +k nr (=1 / τ) relatively smaller is sufficient.

[0081] In formula (1), k r Represents the rate constant of the light-emitting process of the energy donor (equivalent to the fluorescence light-emitting process when explaining energy transfer from the singlet excited state, and equivalent to the phosphorescence or delayed fluorescence light-emitting process when explaining energy transfer from the triplet excited state), k nr Represents the rate constant of the non-light-emitting process (thermal deactivation and intersystem crossing) of the energy donor, τ represents the measured lifetime of the excited state of the energy donor. In addition, k h*→g Represents the rate constant of energy transfer (Förster mechanism or Dexter mechanism).

[0082] [Formula 1]

[0083] In the deuterated compound and the non-deuterated compound, the atomic configuration, spectral shape, etc. of the molecule are almost the same, so the rate constant k of energy transfer h*→gAre substantially the same (refer to the following formula (2) or (3)). From this, it can be seen that when comparing a deuterated compound and a non-deuterated compound, the rate constant k of energy transfer h*→g Is greatly affected by the luminescence lifetime (phosphorescence lifetime or delayed fluorescence lifetime) τ. That is, when the luminescence lifetime (phosphorescence lifetime or delayed fluorescence lifetime) becomes longer, the energy transfer efficiency is improved.

[0084] [Formula 2]

[0085] [Formula 3]

[0086] Formulas (2) and (3) are the formulas for the rate constant k of the Förster mechanism and the Dexter mechanism respectively h*→g Of.

[0087] In formula (2), ν represents frequency, f’ h (ν) represents the normalized emission spectrum of the energy donor (fluorescence spectrum when explaining energy transfer from the singlet excited state, phosphorescence spectrum when explaining energy transfer from the triplet excited state), ε g (ν) represents the molar extinction coefficient of the energy acceptor, N represents Avogadro's number, n represents the refractive index of the medium, R represents the molecular distance between the energy donor and the energy acceptor, τ represents the measured lifetime of the excited state (fluorescence lifetime, phosphorescence lifetime), Represents the luminescence quantum yield (fluorescence quantum yield when explaining energy transfer from the singlet excited state, phosphorescence quantum yield when explaining energy transfer from the triplet excited state), K 2 Is a coefficient (0 to 4) representing the orientation of the transition dipole moments of the energy donor and the energy acceptor. In addition, in random orientation, K 2 = 2 / 3.

[0088] In formula (3), h represents Planck's constant, K represents a constant with an energy dimension, ν represents frequency, f’ h (ν) represents the normalized emission spectrum of the energy donor (fluorescence spectrum when explaining energy transfer from the singlet excited state, phosphorescence spectrum when explaining energy transfer from the triplet excited state), ε’ g (ν) represents the normalized absorption spectrum of the energy acceptor, L represents the effective molecular radius, and R represents the molecular distance between the energy donor and the energy acceptor.

[0089] Thus, by increasing the luminescence lifetime (phosphorescence lifetime or delayed fluorescence lifetime) of the energy donor, the energy transfer efficiency is improved. Therefore, when at least one of Compound 131, Compound 132, and Compound 133, preferably any two compounds, and most preferably all compounds contain deuterium, the energy transfer efficiency is improved and the degradation of the compound is suppressed compared to the case where they are all non-deuterated, thereby enabling a light-emitting device with good reliability to be achieved.

[0090] Note that in Path A2, the exciplex formed by Compound 131 and Compound 132 is used as the energy donor. However, there may be a path where energy is transferred from the triplet excited state of the exciplex through the triplet excited states of Compound 131 and Compound 132. Therefore, the phosphorescence lifetime or delayed fluorescence lifetime of Compound 131 and Compound 132 that form the exciplex is important.

[0091] That is, when Compound 131 contains deuterium, the phosphorescence lifetime or delayed fluorescence lifetime of Compound 131 is preferably longer than that of the non-deuterated Compound 131. Additionally, when Compound 132 contains deuterium, the phosphorescence lifetime or delayed fluorescence lifetime of Compound 132 is preferably longer than that of the non-deuterated Compound 132. Moreover, when Compound 133 contains deuterium, the phosphorescence lifetime or delayed fluorescence lifetime of Compound 133 is preferably longer than that of the non-deuterated Compound 133.

[0092] Note that in this specification, etc., the non-deuterated form of a deuterium-containing compound refers to the compound in which the deuterium of the deuterium-containing compound is hydrogen.

[0093] Set the following time as the phosphorescence lifetime or delayed fluorescence lifetime: As Figure 3 shown, in the decay curve obtained from transient PL (photoluminescence) ( Figure 3 left figure), set an arbitrary point in the range where the intensity decays as a single exponential function as time t = 0 ( Figure 3 right figure), and the time required from this point until the intensity decays to 1 / e times the intensity at t = 0. Ideally, the luminescence decays as a single exponential function. Therefore, in Figure 3 make a graph by setting the time when the intensity reaches 50% of the measurement start time in the measurement data as t = 0, and set the time required for the intensity to reach 1 / e when the intensity at t = 0 is set to 1 as the phosphorescence lifetime or delayed fluorescence lifetime.

[0094] For example, a nitrogen-cooling unit can be set up for a fluorescence photometer such as the FP-8600 manufactured by JASCO Corporation, and the phosphorescence lifetimes of Compound 131 and Compound 132 can be measured at the liquid nitrogen temperature (77K). The solution of the material is prepared in a glove box. The sample is dissolved in deoxygenated 2-methyltetrahydrofuran (2-MeTHF), and stirred with a stirrer at room temperature for about 30 minutes (heating is also performed if the material is not easily soluble) to prepare a solution with a concentration of 1.2E -4 M or so, which can be used for measurement.

[0095] By irradiating the sample cell with excitation light for about 30 seconds, and measuring the decaying luminescence intensity at intervals of 10 ms after blocking the excitation light with a baffle, time-resolved measurement can be performed. As the wavelength for measuring the phosphorescence lifetime, it is preferable to select a wavelength that contains as little fluorescence as possible by comparing the emission spectrum measured at low temperature (e.g., 77K) (the emission spectrum including phosphorescence) and the emission spectrum measured at room temperature (the emission spectrum including only fluorescence and not phosphorescence). Note that the bandwidth of the excitation light and the measurement light is about 10 nm. Ideally, the luminescence decays as a single exponential function. Therefore, the phosphorescence luminescence lifetime can be set as follows: based on the time when the intensity reaches 50% of that at the start of measurement, the time required for the luminescence intensity to decay to 1 / e times.

[0096] The measurement of the luminescence lifetime of Compound 133 can be performed, for example, using a picosecond fluorescence lifetime measurement system (manufactured by Hamamatsu Photonics K.K., Japan). The solution of the material is prepared in a glove box of LABstar M13 (1250 / 780) manufactured by MBRAUN (Braun) company. The sample is dissolved in deoxygenated dichloromethane to prepare a solution with a concentration of 1.5E -5 M, which can be used for measurement. The modulated solution is irradiated with pulsed laser, and the decaying luminescence after laser irradiation is measured by a streak camera in a time-resolved manner. By irradiating the modulated solution with pulsed laser (MNL106PD manufactured by LTB company) at a period of 10 Hz and integrating the repeatedly measured data, data with a high S / N ratio can be obtained. In this case, it is preferable to perform the measurement at room temperature (in an atmosphere maintained at 23°C).

[0097] Note that the fluorescence lifetime, phosphorescence lifetime, and delayed fluorescence lifetime can be distinguished according to the lifetime length during time-resolved measurement. The luminescence lifetime in the order of nanoseconds is the fluorescence lifetime, and the luminescence lifetime in the order of microseconds to milliseconds or more is the phosphorescence lifetime and the delayed fluorescence lifetime.

[0098] For example, preferably, when the light emitted by Compound 134 is light emission in the blue region, that is, when its peak wavelength is typically 450 nm or more and less than 500 nm, Compound 131 contains deuterium, and its phosphorescence lifetime or delayed fluorescence lifetime at 77 K is 1.05 times or more of the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of Compound 131 at 77 K. Additionally, more preferably, Compound 132 contains deuterium, and its phosphorescence lifetime or delayed fluorescence lifetime at 77 K is 1.20 times or more of the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of Compound 132 at 77 K. More preferably, Compound 133 contains deuterium, and its phosphorescence lifetime or delayed fluorescence lifetime at room temperature (any temperature of 290 K or more and 300 K or less, preferably 296 K (23 °C)) is 1.02 times or more of the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of Compound 133 at room temperature (any temperature of 290 K or more and 300 K or less, preferably 296 K (23 °C)).

[0099] In addition, preferably, when the light emitted by Compound 134 is light emission in the green region, that is, when its peak wavelength is typically 500 nm or more and 600 nm or less, Compound 131 contains deuterium, and its phosphorescence lifetime or delayed fluorescence lifetime at 77 K is 1.50 times or more of the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of Compound 131 at 77 K, and Compound 132 contains deuterium, and its phosphorescence lifetime or delayed fluorescence lifetime at 77 K is 3.00 times or more of the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of Compound 132 at 77 K. More preferably, Compound 133 contains deuterium, and its phosphorescence lifetime or delayed fluorescence lifetime at room temperature (any temperature of 290 K or more and 300 K or less, preferably 296 K (23 °C)) is 1.02 times or more of the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of Compound 133 at room temperature (any temperature of 290 K or more and 300 K or less, preferably 296 K (23 °C)).

[0100] Alternatively, in a light-emitting device according to one embodiment of the present invention, the reliability is improved in conjunction with the extension of the phosphorescence lifetime of Compound 131 and Compound 132, that is, the lifetime of triplet excitons. The extension of the lifetime of triplet excitons is due to the suppression of non-radiative inactivation of triplet excitation energy caused by vibration suppression due to deuteration. At this time, when the difference between the T1 energy levels of Compound 131 and Compound 132 is small, the excitation energy is not easily biased towards any one of the organic compounds, and significant deterioration of any one of the organic compounds can be prevented, so the reliability of the light-emitting device is improved, and thus it is preferred. Specifically, the difference between the T1 energy levels of Compound 131 and Compound 132 is 0.20 eV or less, preferably 0.15 eV or less, and more preferably 0.10 eV or less.

[0101] The T1 energy level can be calculated by depositing a 50-nm thin film of a sample on a quartz substrate and measuring the emission spectrum (phosphorescence spectrum) at a measurement temperature of 10 K. In the measurement, it is preferable to use a microscopic PL device, LabRAM HR-PL (manufactured by Horiba, Ltd., Japan), and use a He-Cd laser (325 nm) as the excitation light. Note that a tangent line is drawn at the maximum 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), and the emission end is calculated based on the intersection point of this tangent line with the horizontal axis (wavelength) or the baseline.

[0102] Alternatively, in one embodiment of the present invention, the sublimation temperature of Compound 131 and the sublimation temperature of Compound 132 are preferably close to each other. For example, the difference between the 5% weight loss temperature of Compound 131 measured by thermogravimetric measurement and the 5% weight loss temperature of Compound 132 measured by thermogravimetric measurement is preferably 60 °C or less. More preferably, it is 45 °C or less, further preferably 20 °C or less, and still more preferably 10 °C or less. Thereby, a material in which Compound 131 and Compound 132 are mixed can be used for evaporation deposition, and thus the number of evaporation sources can be reduced to inexpensively provide a light-emitting device with good characteristics.

[0103] The 5% weight loss temperature can be obtained from the relationship between weight and temperature (thermogravimetric analysis) obtained by performing thermogravimetry-differential thermal analysis (TG-DTA: Thermogravimetry-Differential Thermal Analysis). In addition, when the pressure for evaporation deposition is predetermined, it is preferable to use the value measured at this pressure.

[0104] In addition, the photoluminescence (PL) spectrum of the exciplex formed by Compound 131 and Compound 132 preferably overlaps with the PL spectrum of Compound 133. This is because the driving voltage of the light-emitting device can be reduced when the excitation energy of the energy donor is close to the excitation energy of Compound 133. Therefore, the difference between the respective maximum peak wavelengths is preferably 30 nm or less. Alternatively, when the difference between the wavelength of the emission end on the short-wavelength side in the PL spectrum of the exciplex and the wavelength of the emission end on the short-wavelength side in the PL spectrum of Compound 133 is 30 nm or less, the driving voltage of the light-emitting device can be reduced, so it is preferable.

[0105] The PL spectrum of the exciplex is preferably measured using a co-evaporated film of Compound 131 and Compound 132. The sample state when measuring the PL spectrum of Compound 133 can be either a thin film or a solution, but from the viewpoint of verifying the state of isolated molecules, a solution is preferred. The solvent of this solution is not particularly limited when using the same solvent for comparison, but a solvent with a relatively low polarity such as toluene or chloroform is preferred.

[0106] Next, specific examples of the host materials that can be used for Compound 131 and Compound 132, the phosphorescent light-emitting material that can be used for Compound 133, the fluorescent light-emitting material that can be used for Compound 134, and the TADF materials that can be used for Compound 133 or Compound 134 will be described.

[0107] <<Specific Examples of Host Materials>> As described above, the combination of Compound 131 and Compound 132 is preferably a combination capable of forming an exciplex. More preferably, one of them is a hole-transporting material and the other is an electron-transporting material. As the hole-transporting material, for example, compounds having one or both of a π-electron-rich heteroaromatic ring and an aromatic amine skeleton can be cited. As the electron-transporting material, compounds having a π-electron-deficient heteroaromatic ring can be cited.

[0108] The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring including at least one of a furan ring, a thiophene ring, and a pyrrole ring, and specifically preferably a dibenzofuran ring, a dibenzothiophene ring, a carbazole ring, or a ring formed by fusing an aromatic ring or a heteroaromatic ring to these rings.

[0109] Specific examples of the hole-transporting material will be described in Embodiment 2.

[0110] As a compound that is a hole-transporting material and contains deuterium, a compound obtained by deuterating the above hole-transporting material can be cited. In particular, 9-(2-naphthyl-1,3,4,5,6,7,8-d7)-9'-(phenyl-2,3,4,5,6-d5)-3,3'-bi-9H-carbazole-1,1',2,2',4,4',5,5',6,6',7,7',8,8'-d 14 (Abbreviation: βNCCP-d 26 )、9-phenyl-9'-(phenyl-2,3,4,5,6-d5)-3,3'-bis(9H-carbazole) (abbreviation: PCCP-d5), etc., compounds having a carbazole skeleton and containing deuterium have a longer phosphorescence lifetime than non-deuterated ones, so the energy transfer efficiency in the light-emitting layer 113 can be improved, and thus they are preferred.

[0111] As the π-electron-deficient heteroaromatic ring, for example, an oxadiazole ring, a triazole ring, a benzimidazole ring, a quinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a phenanthroline ring, a pyridine ring, a diazine ring (including a pyrimidine ring, a pyrazine ring, a pyridazine ring), a triazine ring, a furandiazine ring, etc. can be cited.

[0112] Specific examples of the electron-transporting material will be described in Embodiment 2.

[0113] In addition, as a compound that is an electron transport material and contains deuterium, examples thereof include compounds obtained by deuterating the above electron transport materials. In particular, 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole-1,2,3,4,5,6,7,8,1',2',3',4',5',6',7',8'-d 16 )(abbreviation: SiTrzCz2-d 16 ), 11-[4-(biphenyl-4-yl-2,2',3,3',4',5,5',6,6'-d9)-6-(phenyl-2,3,4,5,6-d5)-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole-1,2,3,4,5,6,7,8,9,10-d 10 and other compounds having a triazine skeleton and containing deuterium, and 8-(1,1':4',1''-terphenyl-3-yl-2,4,5,6,2',3',5',6',2'',3'',4'',5'',6''-d 13 )-4-[3-(dibenzothiophen-4-yl-1,2,3,6,7,8,9-d7)phenyl-2,4,6-d3]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm-d 23 ), 8-(1,1':4',1''-terphenyl-3-yl-2,4,5,6,2',3',5',6',2'',3'',4'',5'',6''-d 13 )-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm-d 13 ) and other compounds having a benzofuropyrimidine skeleton and containing deuterium have a longer phosphorescence lifetime than non-deuterated compounds and can improve the energy transfer efficiency in the light-emitting layer 113, so they are preferred.

[0114] <<Phosphorescent light-emitting substance>> A phosphorescent light-emitting substance refers to a compound that exhibits phosphorescence but does not exhibit fluorescence at any temperature in the temperature range above low temperature (e.g., 77K) and below room temperature (i.e., above 77K and below 313K). The phosphorescent light-emitting substance preferably contains a metal element with a large spin-orbit interaction, and examples thereof include organometallic complexes, metal complexes (platinum complexes), rare earth metal complexes, etc. Specifically, it preferably contains a transition metal element, and particularly preferably contains a platinum group element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) or platinum (Pt)), and particularly preferably contains iridium. Iridium can increase the probability of direct transition between the singlet ground state and the triplet excited state, so it is preferred.

[0115] Specific examples of the phosphorescent light-emitting material are described in Embodiment 2.

[0116] As a compound that is a phosphorescent light-emitting material and contains deuterium, a compound obtained by deuterating the above phosphorescent light-emitting material can be cited. In particular, [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy-d3)), (2-{3-[3-(3,5-di-tert-butylphenyl)benzimidazol-1-yl-2-ylidene-κC 2 phenoxy-κC 2}-9-[3,5-bis(methyl-d3)-4-phenyl-2-pyridinyl-κN]carbazole-2,1-diyl-κC)platinum(II) (abbreviation: Pt(mmtBubOcz35dm4ppy-d6)), {2-(methyl-d3)-8-[4-(2,2-dimethylpropyl-1,1-d2)-2-pyridinyl-κN]benzofuro[2,3-b]pyridin-7-yl-κC}bis{5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5mtpy-d6)2(mbfpypy-Np-d5)), {2-(methyl-d3)-8-[4-(2,2-dimethylpropyl-1,1-d2)-2-pyridinyl-κN]benzofuro[2,3-b]pyridin-7-yl-κC}bis({2-[(4,5-dimethyl-d6)-2-pyridinyl-κN]-4-(methyl-d3)-3-phenyl}phenyl-κC)iridium(III) (abbreviation: Ir(tm5bpy-d9)2(mbfpypy-Np-d5)), etc. are stable and thus preferred.

[0117] <<Specific examples of the fluorescent light-emitting material>> Compound 134 is a material having a function of converting singlet excitation energy into light emission. When a fluorescent light-emitting material is used as a material having a function of converting singlet excitation energy into light emission, the fluorescent light-emitting material is preferably a compound in which a part of its structure contains a light-emitting body and a protecting group having a function of increasing the distance between the light-emitting body and other energy donors.

[0118] Herein, a lumophore refers to an atomic group (skeleton) that causes luminescence in a fluorescent material. The lumophore generally has a π bond, preferably includes an aromatic ring, and particularly preferably includes a fused aromatic ring or a fused heteroaromatic ring. In addition, as another way, the lumophore can be regarded as an atomic group (skeleton) of an aromatic ring in which a transition dipole vector exists on the ring plane. Further, when a fluorescent material includes a plurality of fused aromatic rings or fused heteroaromatic rings, sometimes the skeleton with the lowest S1 energy level among the plurality of fused aromatic rings or fused heteroaromatic rings is regarded as the lumophore of the fluorescent material. Additionally, sometimes the skeleton having an absorption end on the longest wavelength side among the plurality of fused aromatic rings or fused heteroaromatic rings is regarded as the lumophore of the fluorescent material. Moreover, sometimes the lumophore of the fluorescent material can be predicted based on the shape of the emission spectrum of each of the plurality of fused aromatic rings or fused heteroaromatic rings.

[0119] Examples of the above lumophore include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, a naphthobisbenzofuran skeleton, etc. In particular, fluorescent materials having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, a naphthobisbenzofuran skeleton are preferred because of their high fluorescence quantum yield.

[0120] The substituent used as a protecting group needs to have a triplet excitation energy level higher than the T1 energy levels of the lumophore and the host material. Therefore, a saturated hydrocarbon group is preferably used. This is because substituents without π bonds have a high triplet excitation energy level. In addition, the carrier (electron or hole) transport function of substituents without π bonds is low. Therefore, the saturated hydrocarbon group can increase the distance between the lumophore and the host material with almost no influence on the excited state or carrier transport property of the host material. In addition, in an organic compound that includes both a substituent without a π bond and a substituent with π conjugation, in many cases, the frontier orbitals {HOMO (Highest Occupied Molecular Orbital, also known as the highest occupied molecular orbital) and LUMO (Lowest Unoccupied Molecular Orbital, also known as the lowest unoccupied molecular orbital)} are present on the side of the substituent with π conjugation. In particular, this is often the case for lumophores with frontier orbitals. As described later, when performing energy transfer based on the Dexter mechanism, the overlap of the HOMO and the overlap of the LUMO of the energy donor and the energy acceptor are important. Therefore, by using a saturated hydrocarbon group as the protecting group, the distance between the frontier orbitals of the host material as the energy donor and the frontier orbitals of the guest material as the energy acceptor can be increased, and thus energy transfer based on the Dexter mechanism can be suppressed.

[0121] As specific examples of the protecting group, an alkyl group having 1 or more and 10 or less carbon atoms can be mentioned. Since it is necessary to increase the distance between the lumophore and the host material, the protecting group is preferably a bulky substituent. Therefore, an alkyl group having 3 or more and 10 or less carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 or more and 10 or less carbon atoms, or a trialkylsilyl group having 3 or more and 10 or less carbon atoms can be appropriately used. In particular, the alkyl group is preferably a bulky branched alkyl group. In addition, since the substituent is a bulky substituent when it contains a quaternary carbon, it is particularly preferred.

[0122] In addition, as described above, the protecting group is more preferably deuterated. When the protecting group contains deuterium, as specific examples, an alkyl group having 3 or more and 10 or less carbon atoms containing deuterium, a substituted or unsubstituted cycloalkyl group having 3 or more and 10 or less carbon atoms containing deuterium, or a trialkylsilyl group having 3 or more and 10 or less carbon atoms containing deuterium can be mentioned.

[0123] In addition, it is preferable that there are more than five protecting groups for one light-emitting body. By adopting this structure, the entire light-emitting body can be covered by the protecting groups, so that the distance between the host material and the light-emitting body can be appropriately adjusted. Note that it is more preferable that the protecting group is not directly bonded to the light-emitting body. For example, the protecting group can also be bonded to the light-emitting body through a divalent or higher substituent such as an arylene group or an amino group. By bonding the protecting group to the light-emitting body through this substituent, the distance between the light-emitting body and the host material can be effectively increased. Therefore, when the light-emitting body and the protecting group are not directly bonded, in the case where there are more than four protecting groups for one light-emitting body, the energy transfer based on the Dexter mechanism can be effectively suppressed.

[0124] Specific examples of the fluorescent light-emitting substance including a protecting group having a function of increasing the distance between the light-emitting body and other energy donors include N,N'-(2-phenylanthracene-9,10-diyl)-N,N,N',N'-tetrakis(3,5-di-tert-butylphenyl)diamine (abbreviation: 2Ph-mmtBuDPhA2Anth), 2,2',6,6'-tetrakis(3,5-di-tert-butylphenyl)-N,N,N',N'-tetrakis(3,5-di-tert-butylphenyl)-9,9'-bianthracene-10,10'-diamine (abbreviation: 22'66'mmtBuPh-mmtBuDPhA2BANT), N,N'-bis[3,5-bis(1-adamantyl)phenyl]-N,N'-bis(3,5-di-tert-butylphenyl)-2-phenylanthracene-9,10-diamine (abbreviation: 2Ph-mmAdtBuDPhA2Anth-03), N,N'-bis(3,5-di-tert-butylphenyl)-N,N'-bis{3,5-bis[4-(1-adamantyl)phenyl]phenyl}-2,6-diphenylanthracene-9,10-diamine (abbreviation: 2,6Ph-mmAdPtBuDPhA2Anth), N,N'-bis(3,5-di-tert-butylphenyl)-N,N'-bis{3,5-bis[4-(1-adamantyl)phenyl]phenyl}-2-phenylanthracene-9,10-diamine (abbreviation: 2Ph-mmAdPtBuDPhA2Anth), N,N'-bis{3,5-bis(tricyclo[5.2.1.0 2，6(Decan-8-yl)phenyl}-N,N'-bis(3,5-di-tert-butylphenyl)-2-phenylanthracene-9,10-diamine (abbreviation: 2Ph-mmTCDtBuDPhA2Anth), N,N'-bis{3,5-bis(2-bicyclo[2.2.1]heptyl)phenyl}-N,N'-bis(3,5-di-tert-butylphenyl)-2-phenylanthracene-9,10-diamine (abbreviation: 2Ph-mmnbtBuDPhA2Anth), N,N'-bis[3,5-bis(2-adamantyl)phenyl]-N,N'-bis[3,5-bis(3,5-di-tert-butylphenyl)phenyl]-2-phenylanthracene-9,10-diamine (abbreviation: 2Ph-mmAdtBuDPhA2Anth-02), N,N'-bis[3,5-bis(2-adamantyl)phenyl]-N,N'-bis(3,5-di-tert-butylphenyl)-2-phenylanthracene-9,10-diamine (abbreviation: 2Ph-mmAdtBuDPhA2Anth), N,N'-(2-trimethylsilylanthracene-9,10-diyl)-N,N,N',N'-tetrakis(3,5-di-tert-butylphenyl)diamine (abbreviation: 2TMS-mmtBuDPhA2Anth), N,N'-(pyrene-1,6-diyl)bis[N-(2-methylphenyl)-6-cyclohexylbenzo[b]naphtho[1,2-d]furan-8-amine] (abbreviation: 1,6oMechBnfAPrn), N,N'-(pyrene-1,6-diyl)bis(N-phenyl-6-trimethylsilylbenzo[b]naphtho[1,2-d]furan-8-amine) (abbreviation: 1,6TMSBnfAPrn), N,N'-(3,8-dicyclohexylpyrene-1,6-diyl)bis[N-phenyl-(6-cyclohexylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: ch-1,6chBnfAPrn), N,N'-bis[9-(3,5-di-tert-butylphenyl)-9H-carbazol-2-yl]-N,N'-diphenyl-naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10mmtBuPCA2Nbf(IV)-02). Additionally, materials formed by deuterating the protecting groups of these compounds can be utilized.

[0125] In addition, the fluorescent luminescent substances exemplified in Embodiment 2 can also be used.

[0126] <<Specific examples of TADF materials>> TADF materials are materials with the function of converting both singlet excitation energy and triplet excitation energy into luminescence. As TADF materials, heterocyclic compounds having a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring can be cited. As specific examples, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10’H-spiro[acridine-9,9’-anthracene]-10’-one (abbreviation: ACRSA), etc. can be cited. Since the heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, it has high electron transportability and hole transportability, and thus is preferred. In particular, in the skeleton including a π-electron-deficient heteroaromatic ring, a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) or a triazine skeleton is stable and has good reliability, and thus is preferred. In addition, in the skeleton including a π-electron-rich heteroaromatic ring, an acridine skeleton, a phenoxazine skeleton, a thiophene skeleton, a furan skeleton, and a pyrrole skeleton are stable and have good reliability, and thus it is preferred to have any one or more of these skeletons. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferably used. In addition, in a substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded, both the donor property of the π-electron-rich heteroaromatic ring and the acceptor property of the π-electron-deficient heteroaromatic ring are strong, and the difference between the singlet excitation level and the triplet excitation level becomes small, and thus it is particularly preferred.

[0127] In addition, as TADF materials, fused heteroaromatic compounds containing nitrogen and boron, especially compounds having a diaza-boraphenanthroanthracene skeleton, are preferred because the width of their emission spectra is narrow, and blue luminescence with good color purity can be obtained. As specific examples, 5,9-diphenyl-5,9-diaza-13b-boraphenanthro[3,2,1-de]anthracene (abbreviation: DABNA1), 9-(biphenyl-3-yl)-N,N,5,11-tetraphenyl-5H,9H-[1,4]benzazaborole[2,3,4-kl]phenazaborole-3-amine (abbreviation: DABNA2), 2,12-bis(tert-butyl)-5,9-bis(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzazaborole[2,3,4-kl]phenazaborole-7-amine (abbreviation: DPhA-tBu4DABNA), 2,12-bis(tert-butyl)-N,N,5,9-tetrakis(4-tert-butylphenyl)-5H,9H-[1,4]benzazaborole[2,3,4-kl]phenazaborole-7-amine (abbreviation: tBuDPhA-tBu4DABNA), 2,12-bis(tert-butyl)-5,9-bis(4-tert-butylphenyl)-7-methyl-5H,9H-[1,4]benzazaborole[2,3,4-kl]phenazaborole (abbreviation: Me-tBu4DABNA), N 7 , N 7 , N 13 , N 13 , 5,9,11,15-octaphenyl-5H,9H,11H,15H-[1,4]benzazaborole[2,3,4-kl][1,4]benzazaborole[4’,3’,2’:4,5][1,4]benzazaborole[3,2-b]phenazaborole-7,13-diamine (abbreviation: ν-DABNA), 2-(4-tert-butylphenyl)benzo[5,6]indolo[3,2,1-jk]benzo[b]carbazole (abbreviation: tBuPBibc), etc.

[0128] In addition to these, as TADF materials, 9,10,11-tris[3,6-bis(1,1-dimethylethyl)-9H-carbazol-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3’,2’,1’:8,1][1,4]benzazaborole[2,3,4-kl]phenazaborole (abbreviation: BBCz-G), 9,11-bis[3,6-bis(1,1-dimethylethyl)-9H-carbazol-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3’,2’,1’:8,1][1,4]benzazaborole[2,3,4-kl]phenazaborole (abbreviation: BBCz-Y), etc. can be appropriately used.

[0129] The TADF material refers to a material having a difference between the triplet excited state energy level and the singlet excited state energy level and having the function of converting energy from the triplet excited state to the singlet excited state through reverse intersystem crossing. Therefore, it can convert (up-convert) the triplet excited state to the singlet excited state (reverse intersystem crossing) with a small amount of thermal energy and can efficiently emit light (fluorescence) from the singlet excited state. The conditions for obtaining thermally activated delayed fluorescence with high efficiency are as follows: the difference between the triplet excited state energy level and the singlet excited state energy level is greater than 0 eV and 0.20 eV or less, preferably greater than 0 eV and 0.10 eV or less.

[0130] In addition, the TADF materials exemplified in Embodiment 2 can also be used.

[0131] This embodiment can be used in any combination with other embodiments.

[0132] Embodiment 2 In this embodiment, with reference to Figures 4A to 4F the structure of a light-emitting device according to one aspect of the present invention will be described.

[0133] 〔Basic Structure of Light-Emitting Device〕 The basic structure of the light-emitting device will be described. Figure 4A A light-emitting device having a structure (single structure) in which an organic compound layer having a light-emitting layer is included between a pair of electrodes is shown. Specifically, the organic compound layer 103 is sandwiched between the first electrode 101 and the second electrode 102.

[0134] Figure 4B A light-emitting device having a stacked structure (series structure) in which a plurality of (two layers in Figure 4B ) organic compound layers (103a, 103b) are included between a pair of electrodes and a charge generation layer 106 is included between the organic compound layers is shown. The light-emitting device having a series structure can achieve a highly efficient light-emitting device without changing the amount of current.

[0135] The charge generation layer 106 has the following function: when a potential difference is generated between the first electrode 101 and the second electrode 102, electrons are injected into one organic compound layer (103a or 103b) and holes are injected into the other organic compound layer (103b or 103a). Thus, in Figure 4B when a voltage is applied such that the potential of the first electrode 101 is higher than that of the second electrode 102, the charge generation layer 106 injects electrons into the organic compound layer 103a and injects holes into the organic compound layer 103b.

[0136] In addition, from the viewpoint of light extraction efficiency, the charge generation layer 106 preferably has translucency to visible light (specifically, the visible light transmittance of the charge generation layer 106 is 40% or more). Further, the charge generation layer 106 can function even if its conductivity is lower than those of the first electrode 101 and the second electrode 102.

[0137] Figure 4C The laminated structure of the organic compound layer 103 of a light-emitting device showing one embodiment of the present invention is shown. Note that, in this case, the first electrode 101 is used as an anode and the second electrode 102 is used 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 laminated in this order on the first electrode 101. Note that, as the light-emitting layer 113, a plurality of light-emitting layers having different emission colors may be laminated. For example, a light-emitting layer containing a light-emitting substance that exhibits red, a light-emitting layer containing a light-emitting substance that exhibits green, and a light-emitting layer containing a light-emitting substance that exhibits blue may be laminated with or without a layer containing a charge transport material therebetween. Alternatively, a light-emitting layer containing a light-emitting substance that exhibits yellow and a light-emitting layer containing a light-emitting substance that exhibits blue may be combined. Note that the laminated structure of the light-emitting layer 113 is not limited to the above structure. For example, as the light-emitting layer 113, a plurality of light-emitting layers having the same emission color may be laminated. For example, a first light-emitting layer containing a light-emitting substance that exhibits blue and a second light-emitting layer containing a light-emitting substance that exhibits blue may be laminated with or without a layer containing a charge transport material therebetween. When a plurality of light-emitting layers having the same emission color are laminated, the reliability can sometimes be improved as compared with a single layer. In addition, in the case of Figure 4B a series structure as shown, in the case of having a plurality of organic compound layers, each organic compound layer also has a structure laminated in the above order from the anode side. In addition, when the first electrode 101 is a cathode and the second electrode 102 is an anode, the lamination order of the organic compound layer 103 is reversed. Specifically, 111 on the first electrode 101 of the 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.

[0138] The light-emitting layer 113 in the organic compound layer (103, 103a, 103b) can appropriately combine a light-emitting substance and a plurality of substances to obtain fluorescence emission or phosphorescence emission that exhibits a desired emission color. In addition, the light-emitting layer 113 may have a laminated structure with different emission colors. In this case, different materials may be used as the light-emitting substance and other substances for each light-emitting layer to be laminated. In addition, a structure in which different emission colors are obtained from the Figure 4B plurality of organic compound layers (103a and 103b) shown may be employed. In this case, different materials may be used as the light-emitting substance and other substances for each light-emitting layer.

[0139] In addition, in a light-emitting device according to an aspect of the present invention, for example, by making Figure 4C the first electrode 101 shown in FIG. a reflective electrode, the second electrode 102 a semi-transmissive semi-reflective electrode, and adopting an optical microcavity resonator (microcavity) structure, light obtained from the light-emitting layer 113 in the organic compound layer 103 can be made to resonate between the electrodes, thereby enhancing the light emitted from the second electrode 102. Therefore, high definition is easily achieved. In addition, since the light emission intensity in the front direction of a specific wavelength can be enhanced, low power consumption can be achieved.

[0140] In the case where the first electrode 101 of the light-emitting device is a reflective electrode composed of a laminated structure of a reflective conductive material and a light-transmissive conductive material (transparent conductive film), optical adjustment can be performed by adjusting the thickness of the transparent conductive film. Specifically, it is preferably adjusted in the following manner: when the wavelength of the light obtained from the light-emitting layer 113 is λ, the optical distance (the product of the thickness and the refractive index) between the first electrode 101 and the second electrode 102 is mλ / 2 (note that m is an integer of 1 or more) or a value in the vicinity thereof.

[0141] In addition, in order to amplify the desired light (wavelength: λ) obtained from the light-emitting layer 113, it is preferably adjusted in the following manner: the optical distance from the first electrode 101 to the region (light-emitting region) in the light-emitting layer 113 where the desired light can be 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 can be obtained both become (2m'+1)λ / 4 (note that m' is an integer of 1 or more) or a value in the vicinity thereof. Note that the "light-emitting region" described herein refers to the recombination region of holes and electrons in the light-emitting layer 113.

[0142] By performing the above optical adjustment, the spectrum of a specific monochromatic light that can be obtained from the light-emitting layer 113 can be narrowed, thereby obtaining light emission with good color purity.

[0143] In addition, in the above case, strictly speaking, the optical distance between the first electrode 101 and the second electrode 102 can be said to be the total thickness from the reflection region in the first electrode 101 to the reflection region in the second electrode 102. However, since it is difficult to accurately determine the positions of the reflection regions in the first electrode 101 and the second electrode 102, the above effects can be sufficiently obtained by assuming any position in the first electrode 101 and the second electrode 102 as the reflection region. In addition, strictly speaking, the optical distance between the first electrode 101 and the light-emitting layer capable of obtaining the desired light can be said to be the optical distance between the reflection region in the first electrode 101 and the light-emitting region in the light-emitting layer capable of obtaining the desired light. However, since it is difficult to accurately determine the reflection region in the first electrode 101 and the light-emitting region in the light-emitting layer capable of obtaining the desired light, the above effects can be sufficiently obtained by assuming any position in the first electrode 101 as the reflection region and any position in the light-emitting layer capable of obtaining the desired light as the light-emitting region.

[0144] Figure 4D Shows Figure 4C A modified example of the stacked structure shown. In this case, the first electrode 101 is used as the anode and the second electrode 102 is used as the cathode. In this modified example, a case including a hole blocking layer and an electron blocking layer is shown. That is, the organic compound layer 103 has a structure in which a hole injection layer 111, a hole transport layer 112, an electron blocking layer 116, a light-emitting layer 113, a hole blocking layer 117, an electron transport layer 114, and an electron injection layer 115 are sequentially stacked on the first electrode 101.

[0145] The electron blocking layer 116 is provided, for example, to prevent electrons from passing through the first electrode 101 side from the light-emitting layer 113. In addition, the hole blocking layer 117 is provided, for example, to prevent holes from passing through the second electrode 102 side from the light-emitting layer 113. Note that the electron blocking layer 116 can also be regarded as a part of the hole transport layer 112. In addition, the hole blocking layer 117 can also be regarded as a part of the electron transport layer 114.

[0146] Figure 4E The light-emitting device shown is a light-emitting device having a series structure. By adopting a series structure, a light-emitting device capable of high-brightness light emission can be realized. In addition, since the series structure can reduce the current required to obtain the same brightness compared with a single structure, the reliability can be improved. In addition, the power consumption can be reduced.

[0147] Figure 4F The light-emitting device shown is Figure 4BAn example of a light-emitting device having a series structure as shown in the accompanying drawings has a structure in which three organic compound layers (103a, 103b, 103c) are laminated with charge generation layers (106a, 106b) interposed therebetween. The three organic compound layers (103a, 103b, 103c) each include a light-emitting layer (113a, 113b, 113c), and the light-emitting colors of the respective light-emitting layers can be freely combined. For example, the following structure can be adopted: the light-emitting layer 113a emits blue, the light-emitting layer 113b emits any one of red, green, and yellow, and the light-emitting layer 113c emits blue. However, the following structure can also be adopted: the light-emitting layer 113a emits red, the light-emitting layer 113b emits any one of blue, green, and yellow, and the light-emitting layer 113c emits red.

[0148] In addition, in the light-emitting device according to one embodiment of the present invention described above, at least one of the first electrode 101 and the second electrode 102 is a light-transmissive electrode (transparent electrode, semi-transmissive semi-reflective electrode, etc.). When the light-transmissive electrode is a transparent electrode, the visible light transmittance of the transparent electrode is 40% or more. In addition, when the electrode is a semi-transmissive semi-reflective electrode, the visible light reflectance of the semi-transmissive semi-reflective electrode is 20% or more and 80% or less, preferably 40% or more and 70% or less. In addition, the resistivity of these electrodes is preferably 1×10 -2 Ω·cm or less.

[0149] In addition, in the light-emitting device according to one embodiment of the present invention described above, when one of the first electrode 101 and the second electrode 102 is a reflective electrode (reflective electrode), the visible light reflectance of the reflective electrode is 40% or more and 100% or less, preferably 70% or more and 100% or less. In addition, the resistivity of this electrode is preferably 1×10 -2 Ω·cm or less.

[0150] 〔Specific Structure of Light-Emitting Device〕 Next, the specific structure of the light-emitting device according to one embodiment of the present invention will be described. In addition, reference is made here to a Figure 4E having a series structure for explanation. Note that Figure 4A and Figure 4C The light-emitting device having a single structure shown also has the same structure of the organic compound layer. In addition, in Figure 4E When the light-emitting device shown has a microcavity structure, a reflective electrode is formed as the first electrode 101, and a semi-transmissive semi-reflective electrode is formed as the second electrode 102. Thus, a desired electrode material can be used alone or multiple electrode materials can be used to form the above electrodes in a single layer or a stacked layer. In addition, the second electrode 102 is formed by appropriately selecting a material after forming the organic compound layer 103b.

[0151] 〔Materials of the light-emitting device〕 <The first electrode and the second electrode> As materials for forming the first electrode 101 and the second electrode 102, the following materials can be appropriately combined as long as they can satisfy the functions of the above two electrodes. For example, metals, alloys, conductive compounds, and their mixtures can be appropriately used. Specifically, indium-tin oxide (also known as ITO), indium-silicon-tin oxide (also known as ITSO), indium-zinc oxide, indium-tungsten-zinc oxide can be cited. In addition to the above, 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) and other metals and alloys obtained by appropriately combining them can be cited. In addition to the above, elements belonging to Group 1 or Group 2 of the periodic table (for example, lithium (Li), cesium (Cs), calcium (Ca), strontium (Sr)), rare earth metals such as europium (Eu), ytterbium (Yb), alloys obtained by appropriately combining them, and graphene can be used.

[0152] In Figure 4F In the case where the first electrode 101 is an anode in the light-emitting device shown, a hole injection layer 111a and a hole transport layer 112a of the organic compound layer 103a are sequentially laminated on the first electrode 101 by a vacuum evaporation method. After forming the organic compound layer 103a and the charge generation layer 106, similarly to the above, a hole injection layer 111b and a hole transport layer 112b of the organic compound layer 103b are sequentially laminated on the charge generation layer 106.

[0153] In addition, in Figures 4A to 4F In each of the light-emitting devices shown, by making the first electrode 101 a reflective electrode, the second electrode 102 a semi-transmissive semi-reflective electrode, and adopting an optical microcavity resonator (microcavity) structure, the light obtained from the light-emitting layer 113 in the organic compound layer 103 can resonate between the above electrodes, thereby enhancing the light emitted from the second electrode 102.

[0154] In the case where the first electrode 101 of the light-emitting device is a reflective electrode composed of a laminated structure of a reflective conductive material and a light-transmissive conductive material (transparent conductive film), optical adjustment can be performed by adjusting the thickness of the transparent conductive film. Specifically, it is preferably adjusted in the following manner: when the wavelength of the light obtained from the light-emitting layer 113 is λ, the optical distance (the product of the thickness and the refractive index) between the first electrode 101 and the second electrode 102 is mλ / 2 (note that m is an integer of 1 or more) or a value near it.

[0155] In addition, in order to amplify the desired light (wavelength: λ) obtained from the light-emitting layer 113, it is preferably adjusted such that the optical distance from the first electrode 101 to the region (light-emitting region) in the light-emitting layer 113 where the desired light can be 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 can be obtained both become (2m'+1)λ / 4 (note that m' is an integer of 1 or more) or a value near it. Note that the "light-emitting region" described here refers to the recombination region of holes and electrons in the light-emitting layer 113.

[0156] By performing the above optical adjustment, the spectrum of a specific monochromatic light that can be obtained from the light-emitting layer 113 can be narrowed, thereby obtaining light emission with good color purity.

[0157] In addition, in the above case, strictly speaking, the optical distance between the first electrode 101 and the second electrode 102 can be said to be the total thickness from the reflection region in the first electrode 101 to the reflection region in the second electrode 102. However, since it is difficult to accurately determine the positions of the reflection regions in the first electrode 101 and the second electrode 102, the above effect can be sufficiently obtained by assuming any position in the first electrode 101 and the second electrode 102 as the reflection region. In addition, strictly speaking, the optical distance between the first electrode 101 and the light-emitting layer where the desired light can be obtained can be said to be the optical distance between the reflection region in the first electrode 101 and the light-emitting region in the light-emitting layer where the desired light can be obtained. However, since it is difficult to accurately determine the reflection region in the first electrode 101 and the light-emitting region in the light-emitting layer where the desired light can be obtained, the above effect can be sufficiently obtained by assuming any position in the first electrode 101 as the reflection region and any position in the light-emitting layer where the desired light can be obtained as the light-emitting region.

[0158] In addition, in the light-emitting device according to one aspect of the present invention described above, at least one of the first electrode 101 and the second electrode 102 is an electrode having translucency (transparent electrode, semi-transmissive and semi-reflective electrode, etc.). When the electrode having translucency is a transparent electrode, the visible light transmittance of the transparent electrode is 40% or more. In addition, when the electrode is a semi-transmissive and semi-reflective electrode, the visible light reflectance of the semi-transmissive and semi-reflective electrode is 20% or more and 80% or less, preferably 40% or more and 70% or less. In addition, the resistivity of these electrodes is preferably 1×10 -2 Ω·cm or less.

[0159] In addition, in the light-emitting device according to one embodiment of the present invention described above, when one of the first electrode 101 and the second electrode 102 is a reflective electrode, the visible light reflectivity of the reflective electrode is 40% or more and 100% or less, preferably 70% or more and 100% or less. Further, the resistivity of this electrode is preferably 1×10 -2 Ω·cm or less.

[0160] <Hole injection layer> The hole injection layer (111, 111a, 111b) is a layer that injects holes from the first electrode 101 of the anode and the charge generation layer (106, 106a, 106b) into the organic compound layer (103, 103a, 103b), and includes an organic acceptor material and a material with high hole injection properties.

[0161] The organic acceptor material can generate holes in the organic compound by charge separation with other organic compounds whose HOMO energy level value is close to the LUMO energy level value. Therefore, as the organic acceptor material, compounds having an electron-withdrawing group (halogen group or cyano group) such as quinodimethane derivatives, tetrachlorobenzoquinone derivatives, and hexaazatriphenylene derivatives can be used. For example, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), 3,6-difluoro-2,5,7,7,8,8-hexacyano-p-benzoquinodimethane, 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), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene) malononitrile, etc. can be used. Among the organic acceptor materials, compounds such as HAT-CN in which an electron-withdrawing group is bonded to a condensed aromatic ring having a plurality of heteroatoms have higher acceptor properties and the film quality has thermal stability, so they are particularly preferred. In addition, [3]axylene derivatives including an electron-withdrawing group (especially a halogen group such as a fluorine group or a cyano group) have very high electron-accepting properties and are therefore preferred. Specifically, α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzyl cyanide], α,α',α''-1,2,3-cyclopropanetriyl tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzyl cyanide], α,α',α''-1,2,3-cyclopropanetriyl tris[2,3,4,5,6-pentafluorobenzyl cyanide], etc. can be used.

[0162] As a material with high hole injection properties, oxides of metals belonging to Groups 4 to 8 of the periodic table (transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc.) can be used. Specifically, molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide can be cited. Among them, molybdenum oxide is particularly preferred because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle. In addition, diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA), 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA-F6), 3,4,9,10-perylenetetracarboxylic diimide (abbreviation: PTCDI), 3,4,9,10-perylenetetracarboxylic-bis-benzimidazole (abbreviation: PTCBI) and other perylene tetracarboxylic acid derivatives, (C 60 -Ih)[5,6]fullerene (abbreviation: C 60 ), (C 70 -D5h)[5,6]fullerene (abbreviation: C 70 ), phthalocyanine (abbreviation: H2Pc) and other organic compounds, copper phthalocyanine (abbreviation: CuPc), zinc phthalocyanine (abbreviation: ZnPc), cobalt phthalocyanine (abbreviation: CoPc), iron phthalocyanine (abbreviation: FePc), tin phthalocyanine (abbreviation: SnPc), tin oxide phthalocyanine (abbreviation: SnOPc), titanium oxide phthalocyanine (abbreviation: TiOPc), vanadium oxide phthalocyanine (abbreviation: VOPc) and other metal phthalocyanines and their derivatives containing copper, zinc, cobalt, iron, chromium, nickel, etc. In addition, phthalocyanine metal complexes such as CuPc or ZnPc or 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine are particularly preferred. In particular, CuPc and ZnPc are inexpensive and have good properties, so they are preferred. Furthermore, ZnPc has a small diffusion coefficient for silicon, reducing the possibility of affecting semiconductor properties due to metal diffusion into the semiconductor, so it is particularly suitable for display devices using silicon semiconductors.

[0163] In addition to the above materials, aromatic amine compounds such as the following low molecular weight compounds can also be used, such as 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis-[4-bis(3-methylphenyl)aminophenyl]-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), etc.

[0164] In addition, high molecular weight compounds (oligomers, dendrimers, polymers, etc.) can be used, 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), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD), etc. Alternatively, high molecular weight compounds added with an acid can also be used, such as poly(3,4-ethylenedioxythiophene) / (polystyrenesulfonic acid) (abbreviation: PEDOT / PSS), polyaniline / (polystyrenesulfonic acid) (abbreviation: PAni / PSS), etc.

[0165] As a material with high hole injection properties, a mixed material containing a hole transport material and the above organic acceptor material (electron acceptor material) can also be used. In this case, electrons are extracted from the hole transport material by the organic acceptor material to generate holes in the hole injection layer 111, and the holes are injected into the light-emitting layer 113 through the hole transport layer 112. In addition, the hole injection layer 111 can be a single layer composed of a mixed material containing a hole transport material and an organic acceptor material (electron acceptor material), or can be a laminate of layers formed by separately using a hole transport material and an organic acceptor material (electron acceptor material).

[0166] As the hole transport material, it is preferably used that the hole mobility is 1×10 when the square root of the electric field strength [V / cm] is 600 -6 cm2 Substances with a voltage of / Vs or higher. In addition, as long as the substance has a higher hole transport property than the electron transport property, substances other than the above can be used.

[0167] As the hole transport material, compounds having a π - electron - rich heteroaromatic ring (e.g., carbazole derivatives, furan derivatives, or thiophene derivatives) and aromatic amines (organic compounds containing an aromatic amine skeleton) and the like are preferably used as the hole transport material.

[0168] As the carbazole derivative (organic compound including a carbazole ring), a bi - carbazole derivative (e.g., 3,3'-bi - carbazole derivative), an aromatic amine having a carbazolyl group, etc. can be mentioned.

[0169] As the bi - carbazole derivative (e.g., 3,3'-bi - carbazole derivative), specifically, 9,9'-diphenyl - 9H,9'H - 3,3'-bi - carbazole (abbreviation: PCCP), 9,9'-bis(biphenyl - 4 - yl)-3,3'-bi - 9H - carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl - 3 - yl)-3,3'-bi - 9H - carbazole (abbreviation: BismBPCz), 9-(biphenyl - 3 - yl)-9'-(biphenyl - 4 - yl)-9H,9'H - 3,3'-bi - carbazole (abbreviation: mBPCCBP), 9-(2 - naphthyl)-9'-phenyl - 3,3'-bi - 9H - carbazole (abbreviation: βNCCP), etc. can be mentioned.

[0170] As an aromatic amine having a carbazolyl group, specifically, 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]bis(9,9-dimethyl-9H-fluoren-2-yl)amine (abbreviation: PCBFF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-4-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-(9,9-dimethyl-9H-fluoren-2-yl)-9,9-dimethyl-9H-fluoren-4-amine, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-diphenyl-9H-fluoren-2-amine, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-diphenyl-9H-fluoren-4-amine, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi(9H-fluorene)-2-amine, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi(9H-fluorene)-4-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-(1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-(1,1':4',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-(1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-4-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-(1,1':4',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-4-amine, 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-bis(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), N-(9,9-spirobi[9H-fluorene]-2-yl)-N,9-diphenylcarbazol-3-amine (abbreviation: PCASF), N-(4-biphenyl)-4-(carbazol-9-yl)phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), etc.

[0171] As carbazole derivatives, 9-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]phenanthrene (abbreviation: PCPPn), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz), 9'-phenyl-9'H-9,3':6',9''-tercarbazole (abbreviation: PSiCzGI), 3,9-bis(9-phenyl-9H-carbazol-3-yl)-9H-carbazole (abbreviation: PCCzPC), 9-(biphenyl-4-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzBP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylene-2-yl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, etc. can also be cited.

[0172] As furan derivatives (organic compounds including a furan ring), specifically, 4,4’,4”-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), etc. can be cited.

[0173] In addition, as thiophene derivatives (organic compounds including a thiophene ring), specifically, 4,4’,4”-(benzene-1,3,5-triyl)tris(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), etc., organic compounds having a thiophene ring, etc. can be cited.

[0174] In addition, as aromatic amines, specifically, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluorene]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), N-(9,9-spirobi[9H-fluorene]-2-yl)-N,N'N'-triphenyl-1,4-phenylenediamine (abbreviation: DPASF), N,N'-diphenyl-N,N'-bis(4-diphenylaminophenyl)spirobi[9H-fluorene]-2,7-diamine (abbreviation: DPA2SF), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: m-MTDATA), N,N'-bis(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), DNTPD, 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophene-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'-binaphthalen-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthalen-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-diphenyl-4''-(7-phenyl)naphthalen-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthalen-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthalen-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthalen-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-(5;2'-binaphthalen-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenyl)-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 (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-Spirobi[9H-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-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'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-1-amine, etc.

[0175] In addition, as the hole transport material, a high molecular compound (oligomer, dendrimer, polymer, etc.) can be used, 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), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD), etc. Alternatively, a high molecular compound added with an acid can also be used, such as poly(3,4-ethylenedioxythiophene) / (polystyrenesulfonic acid) (abbreviation: PEDOT / PSS), polyaniline / (polystyrenesulfonic acid) (abbreviation: PAni / PSS), etc.

[0176] Note that the hole transport material is not limited to the above materials, and one or a combination of various known materials can also be used as the hole transport material. Note that when the above hole transport material is used in the light-emitting layer, a compound in which one or all of the hydrogens are replaced with deuterium can also be used. At this time, the energy transfer efficiency in the light-emitting layer can be improved and the deterioration of the compound can be suppressed, thereby improving the reliability of the light-emitting device.

[0177] Note that the hole injection layer (111, 111a, 111b) can be formed by various known deposition methods, for example, it can be formed by vacuum evaporation.

[0178] <Hole Transport Layer> The hole transport layer (112, 112a, 112b) is a layer that transports holes injected from the first electrode 101 by the hole injection layer (111, 111a, 111b) to the light-emitting layer (113, 113a, 113b). In addition, the hole transport layer (112, 112a, 112b) is a layer containing a hole transport material. Therefore, as the hole transport layer (112, 112a, 112b), a hole transport material that can be used for the hole injection layer (111, 111a, 111b) can be used.

[0179] Note that in the light-emitting device according to one embodiment of the present invention, the same organic compound as the hole transport layer (112, 112a, 112b) can be used for the light-emitting layer (113, 113a, 113b). When the same organic compound is used for the hole transport layer (112, 112a, 112b) and the light-emitting layer (113, 113a, 113b), holes can be efficiently transported from the hole transport layer (112, 112a, 112b) to the light-emitting layer (113, 113a, 113b), which is therefore preferable.

[0180] <Electron blocking layer> The electron blocking layer 116 is provided to prevent electrons from passing through the first electrode 101 side from the light-emitting layer 113. The electron blocking layer 116 preferably uses a material having high hole transportability, low electron transportability, and a high LUMO energy level. Preferably, a material is selected from the substances exemplified as the materials that can be used as the hole transport layer 112 above, and the LUMO energy level of the material is higher than the LUMO energy level of the material constituting the light-emitting layer (at least the host material). Preferably, a material having a LUMO energy level higher by 0.30 eV or more is used to form the electron blocking layer 116. Note that the electron blocking layer transports holes and can thus also be regarded as a part of the hole transport layer 112.

[0181] <Light-emitting layer> The light-emitting layer (113, 113a, 113b) has the structure described in Embodiment 1 and contains a light-emitting substance. Note that as the light-emitting substance that can be used for the light-emitting layer (113, 113a, 113b), a substance that emits light in a light-emitting color such as blue, purple, blue-violet, green, yellow-green, yellow, orange, red, etc. can be appropriately used. In addition, when including a plurality of light-emitting layers, by using different light-emitting substances in each light-emitting layer, a structure that emits different light-emitting colors can be obtained (for example, white light obtained by combining light-emitting colors in a complementary color relationship). In addition, when including a plurality of light-emitting layers, each light-emitting layer can also emit the same color. When stacking a plurality of light-emitting layers having the same light-emitting color, the reliability can sometimes be improved compared to a single layer. Furthermore, a stacked structure in which one light-emitting layer contains different light-emitting substances can also be adopted.

[0182] <<Material having a function of converting singlet excitation energy into luminescence>> As materials having a function of converting singlet excitation energy into luminescence and capable of being used in a light-emitting layer (113, 113a, 113b), the following fluorescent substances (fluorescent luminescent substances) can be cited. For example, pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, naphthalene derivatives, etc. In particular, pyrene derivatives have a high luminescence quantum yield, so they are preferred. As specific examples of pyrene derivatives, N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(dibenzofuran-2-yl)-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6FrAPrn), N,N'-bis(dibenzothiophene-2-yl)-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-6-amine] (abbreviation: 1,6BnfAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-02), N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), etc. can be cited.

[0183] In addition, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenyl-4,4'-stilbenediamine (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), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), 4-[4-(10-phenyl-9-anthryl)phenyl]-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPBA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP), N,N''-(2-tert-butylanthracene-9,10-diyl-di-4,1-phenylene)bis(N,N',N'-triphenyl-1,4-benzenediamine) (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-benzenediamine (abbreviation: 2DPAPPA), etc. can be used.

[0184] In addition, 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]vinyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-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)vinyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]vinyl}-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)vinyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), 1,6BnfAPrn-03, 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), 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02), etc. In particular, pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, 1,6BnfAPrn-03, etc. can be used.;

[0185] <<Materials with the function of converting triplet excitation energy into luminescence>> Next, as a material with the function of converting triplet excitation energy into luminescence that can be used in the light-emitting layer 113, for example, a phosphorescent substance (phosphorescent luminescent substance) can be cited.

[0186] A phosphorescent luminescent substance refers to a compound that exhibits phosphorescence and does not exhibit fluorescence at any temperature in the temperature range above low temperature (e.g., 77K) and below room temperature (i.e., above 77K and below 313K). This phosphorescent luminescent substance preferably contains a metal element with a large spin-orbit interaction, and examples include organometallic complexes, metal complexes (platinum complexes), rare earth metal complexes, etc. Specifically, it preferably contains a transition metal element, and particularly preferably contains a platinum group element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt)), and particularly preferably contains iridium. Iridium can increase the probability of direct transition between the singlet ground state and the triplet excited state, so it is preferred.

[0187] <<Phosphorescent luminescent substance (above 450nm and below 570nm: blue or green)>> As a phosphorescent luminescent substance that exhibits blue or green and has a peak wavelength of its emission spectrum above 450nm and below 570nm, the following substances can be cited.

[0188] For example, organoiridium complexes containing a 4H-triazole ring 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]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazole)iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviation: [Ir(iPr5btz)3]); organoiridium complexes containing a 1H-triazole ring such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazole]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]); organoiridium complexes containing an imidazole ring such as fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpim)3]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]); and organoiridium complexes with a phenylpyridine derivative having an electron-withdrawing group as a ligand such as bis[2-(4’,6’-difluorophenyl)pyridinato-N,C2’]iridium(III) tetra(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4’,6’-difluorophenyl)pyridinato-N,C2’]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’ iridium(III) acetylacetonate (abbreviation: FIr(acac)); and organoplatinum complexes such as (2-{3-[3-(3,5-di-tert-butylphenyl)benzimidazol-1-yl-2-ylidene-κC 2 phenoxy-κC 2}-9-(4-tert-butyl-2-pyridinyl-κN)carbazole-2,1-diyl-κC 1 )platinum(II) (abbreviation: PtON-TBBI), etc.

[0189] <<Phosphorescent luminescent substance (above 495 nm and below 590 nm: green or yellow)>> As a phosphorescent luminescent substance that exhibits green or yellow and has a peak wavelength of the emission spectrum of 495 nm or more and 590 nm or less, the following substances can be cited.

[0190] For example, the following can be cited: tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-tert-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-norbornanyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: [Ir(dmppm-dmp)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]) and other organic iridium complexes including a pyrimidine ring; (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazine)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazine)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]) and other organic iridium complexes including a pyrazine ring; tris(2-phenylpyridine-N,C 2’ )iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridine-N,C 2’ )iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinoline)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinoline)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinoline-N,C 2’ )iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinoline-N,C 2’) Iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), bis[2-(2-pyridyl-κN)phenyl-κC][2-(4-phenyl-2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(4dppy)]), bis[2-(2-pyridyl-κN)phenyl-κC][2-(4-methyl-5-phenyl-2-pyridyl-κN)phenyl-κC], [2-d3-methyl-8-(2-pyridyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)), {2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridyl-κN]benzofuro[2,3-b]pyridin-7-yl-κC}bis{5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5mtpy-d6)2(mbfpypy-iPr-d4)), [2-d3-methyl-(2-pyridyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy-d3)), [2-(4-methyl-5-phenyl-2-pyridyl-κN)phenyl-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mdppy)), etc. organic iridium complexes including pyridine rings; bis(2,4-diphenyl-1,3-oxazole-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(dpo)2(acac)]), bis{2-[4’-(perfluorophenyl)phenyl]pyridine-N,C 2’}iridium(III) acetylacetonate (abbreviation: [Ir(p-PF-ph)2(acac)]), bis(2-phenylbenzothiazole-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(bt)2(acac)]), etc. organometallic complexes; and tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]) etc. rare earth metal complexes.

[0191] <<Phosphorescent luminescent substance (above 570 nm and below 750 nm: yellow or red)>> As phosphorescent luminescent substances that exhibit yellow or red and whose peak wavelength of the emission spectrum is above 570 nm and below 750 nm, the following substances can be cited.

[0192] For example, organometallic complexes including pyrimidine rings such as bis[4,6-bis(3-methylphenyl)pyrimidinato](diisobutyrylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dineopentanoylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), (dineopentanoylmethanato)bis[4,6-bis(naphthalen-1-yl)pyrimidinato]iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]); bis(2,3,5-triphenylpyrazinato)(acetylacetonato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dineopentanoylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinato-κN]phenyl-κC}(2,6-dimethyl-3,5-heptanedionato-κ 2 O,O’)iridium(III) (abbreviation: [Ir(dmdppr-P)2(dibm)]), bis{4,6-dimethyl-2-[5-(4-cyano-2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinato-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ 2 O,O’)iridium(III) (abbreviation: [Ir(dmdppr-dmCP)2(dpm)]), bis{2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinato-κN]-4,6-dimethylphenyl-κC}(2,2’,6,6’-tetramethyl-3,5-heptanedionato-κ 2 O,O’)iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(dpm)]), (acetylacetonato)bis(2-methyl-3-phenylquinoxalinato-N,C 2’ )iridium(III) (abbreviation: [Ir(mpq)2(acac)]), (acetylacetonato)bis(2,3-diphenylquinoxalinato-N,C 2’ )iridium(III) (abbreviation: [Ir(dpq)2(acac)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]) and other organometallic complexes including pyrazine rings; tris(1-phenylisoquinolinato-N,C 2’ )iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’)Iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]) and bis[4,6-dimethyl-2-(quinolin-2-yl-κN)phenyl-κC](2,4-pentanedionato-κ 2 O,O’)iridium(III) (abbreviation: [Ir(dmpqn)2(acac)]) and other organometallic complexes including pyridine rings; platinum complexes such as platinum(II) 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin (abbreviation: [PtOEP]); or 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-thienoyl)-3,3,3-trifluoroacetone](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]).

[0193] <<TADF material>> As the TADF material, the following materials can be used. The TADF material refers to a material in which the energy difference between the S1 energy level and the T1 energy level is small (preferably 0.20 eV or less) and which can convert the triplet excited state into a singlet excited state (reverse intersystem crossing) using a small amount of thermal energy and emit light (fluorescence) from the singlet excited state with high efficiency. The conditions for obtaining thermally activated delayed fluorescence with high efficiency are as follows: the energy difference between the triplet excited energy level and the singlet excited energy level is 0.00 eV or more and 0.20 eV or less, preferably 0.00 eV or more and 0.10 eV or less. The delayed fluorescence emitted by the TADF material refers to light emission having the same spectrum as ordinary fluorescence but a very long lifetime. Its lifetime is 1×10 -6 seconds or more or 1×10 -3 seconds or more.

[0194] In addition, the TADF material can be used as an electron transport material, a hole transport material, or a host material.

[0195] As TADF materials, for example, fullerenes and their derivatives, acridine derivatives such as proflavine, eosin, etc. can be cited. In addition, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), etc. can be cited. As the metal-containing porphyrins, for example, protoporphyrin-tin fluoride complex (abbreviation: SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (abbreviation: SnF2(HematoIX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviation: SnF2(OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF2(Etio I)), octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2OEP), etc. can be cited.

[0196] [Chemical formula 1]

[0197] In addition to the above, heteroaromatic compounds such as 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10’H-spiro[acridine-9,9’-anthracene]-10’-one (abbreviation: ACRSA), 4-(9’-phenyl-3,3’-bi-9H-carbazol-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9’-phenyl-3,3’-bi-9H-carbazol-9-yl)phenyl]benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzPBfpm), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9’-phenyl-2,3’-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), etc., which have π-electron-rich heteroaromatic compounds and π-electron-deficient heteroaromatic compounds.

[0198] In addition, among substances in which a π-electron-rich heteroaromatic compound and a π-electron-deficient heteroaromatic compound are directly bonded, the donating property of the π-electron-rich heteroaromatic compound and the accepting property of the π-electron-deficient heteroaromatic compound are both strong, and the energy difference between the singlet excited state and the triplet excited state becomes small, so it is particularly preferred. In addition, as the TADF material, a TADF material (TADF100) in a thermal equilibrium state between the singlet excited state and the triplet excited state can also be used. Since the luminescence lifetime (excitation lifetime) of this TADF material is short, the efficiency reduction in the high-brightness region of the light-emitting device can be suppressed.

[0199] [Chemical formula 2]

[0200] In addition to the above, as a material having the function of converting triplet excitation energy into light emission, a nanostructure of a transition metal compound having a perovskite structure can be cited. Metal halide perovskite nanostructures are particularly preferred. As the nanostructure, nanoparticles and nanorods are preferred.

[0201] In the light-emitting layers (113, 113a, 113b, 113c), as the organic compound (host material, etc.) used in combination with the above light-emitting substance (guest material), one or more substances having a larger energy gap than the light-emitting substance (guest material) can be selected and used.

[0202] <<Fluorescent light-emitting host material>> When the light-emitting substance used in the light-emitting layer (113, 113a, 113b, 113c) is a fluorescent light-emitting substance, as the organic compound (host material) used in combination with the light-emitting substance, an organic compound having a large energy level of its singlet excited state and a small energy level of its triplet excited state or an organic compound having a high fluorescence quantum yield is preferably used. Therefore, as long as the organic compound satisfies the above conditions, the hole transport material (the above) and the electron transport material (described later) shown in the present embodiment can be used. Note that when the above hole transport material is used in the light-emitting layer, a compound in which a part or all of hydrogen is replaced by deuterium can also be used. At this time, the energy transfer efficiency in the light-emitting layer can be improved and the deterioration of the compound can be suppressed, thereby improving the reliability of the light-emitting device.

[0203] Although a part of the content overlaps with the above specific examples, from the viewpoint of being preferably used in combination with the light-emitting substance (fluorescent light-emitting substance), as the organic compound (host material), anthracene derivatives, tetracene derivatives, phenanthrene derivatives, pyrene derivatives, (chrysene) derivatives, dibenzo[g,p] derivatives and other fused polycyclic aromatic compounds can be cited.

[0204] Specific examples of the organic compound (host material) preferably used in combination with the fluorescent substance include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), YGAPA, PCAPA, N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenyl N,N,N’,N’,N”,N”,N”’,N”’-octaphenyldibenzo[g,p] -2,7,10,15 - tetraamine (abbreviation: DBC1), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4’-(9-phenyl-9H-fluoren-9-yl)biphenyl-4-yl]anthracene (abbreviation: FLPPA), 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,β-ADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthryl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 2,9-di(1-naphthyl)-10-phenylanthracene (abbreviation: 2αN-αNPhA), 9-(1-naphthyl)-10-[3-(1-naphthyl)phenyl]anthracene (abbreviation: αN-mαNPAnth), 9-(2-naphthyl)-10-[3-(1-naphthyl)phenyl]anthracene (abbreviation: βN-mαNPAnth), 9-(1-naphthyl)-10-[4-(1-naphthyl)phenyl]anthracene (abbreviation: αN-αNPAnth), 9-(2-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: βN-βNPAnth), 2-(1-naphthyl)-9-(2-naphthyl)-10-phenylanthracene (abbreviation: 2αN-βNPhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-{4-[10-(biphenyl-4-yl)-9-anthryl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), 9,9’-bianthracene (abbreviation: BANT), 9,9’-(stilbene-3,3’-diyl)diphenanthrene (abbreviation: DPNS), 9,9’-(stilbene-4,4’-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-tris(1-pyrenyl)benzene (abbreviation: TPB3), 5,12-diphenyltetracene, 5,12-bis(biphenyl-2-yl)tetracene, etc.

[0205] <<Phosphorescent light-emitting host material>> When the luminescent material for the light-emitting layer (113, 113a, 113b, 113c) is a phosphorescent luminescent material, as the organic compound (host material) used in combination with the luminescent material, an organic compound whose triplet excitation energy (the energy difference between the ground state and the triplet excited state) is greater than that of the luminescent material can be selected. Note that when multiple organic compounds (for example, a first host material and a second host material (or auxiliary material), etc.) are used in combination with the luminescent material to form an exciplex, it is preferable to use these multiple organic compounds in admixture with the phosphorescent luminescent material.

[0206] By adopting such a structure, luminescence by ExTET (Exciplex-Triplet Energy Transfer) utilizing energy transfer from the exciplex to the luminescent material can be obtained efficiently. As a combination of multiple organic compounds, a combination that easily forms an exciplex is preferably used, and a combination of a compound that easily accepts holes (hole transport material) and a compound that easily accepts electrons (electron transport material) is particularly preferred.

[0207] Although some content overlaps with the above specific examples, from the viewpoint of a preferred combination with the luminescent material (phosphorescent luminescent material), examples of the organic compound (host material, auxiliary material) can include aromatic amines (organic compounds having an aromatic amine skeleton), carbazole derivatives (organic compounds having a carbazole ring), dibenzothiophene derivatives (organic compounds having a dibenzothiophene ring), dibenzofuran derivatives (organic compounds having a dibenzofuran ring), oxadiazole derivatives (organic compounds having an oxadiazole ring), triazole derivatives (organic compounds having a triazole ring), benzimidazole derivatives (organic compounds having a benzimidazole ring), quinoxaline derivatives (organic compounds having a quinoxaline ring), dibenzoquinoxaline derivatives (organic compounds having a dibenzoquinoxaline ring), pyrimidine derivatives (organic compounds having a pyrimidine ring), triazine derivatives (organic compounds having a triazine ring), pyridine derivatives (organic compounds having a pyridine ring), bipyridine derivatives (organic compounds having a bipyridine ring), phenanthroline derivatives (organic compounds having a phenanthroline ring), furandiazine derivatives (organic compounds having a furandiazine ring), zinc and aluminum metal complexes, etc.

[0208] Note that among the above organic compounds, as specific examples of the aromatic amine and carbazole derivatives having high hole transport properties, the same materials as the specific examples of the above hole transport materials can be cited, and these materials are preferably used as the host material.

[0209] In addition, among the above-mentioned organic compounds, specific examples of dibenzothiophene derivatives and dibenzofuran derivatives, which are organic compounds with high hole-transporting properties, include 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4',4''-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviation: DBF3P-II), DBT3P-II, 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II), etc. These materials are preferably used as host materials.

[0210] In addition, metal complexes having oxazole-based ligands and thiazole-based ligands, such as bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviation: ZnBTZ), etc., can also be cited as preferred host materials.

[0211] In addition, among the above-mentioned organic compounds, specific examples of oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, quinazoline derivatives, phenanthroline derivatives, etc. as organic compounds with high electron transport properties include 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2 Organic compounds containing a heteroaromatic ring having an azole ring, such as 4-triazole (abbreviation: TAZ), 2,2',2"-(1,3,5-phenyltriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), bathophenanthroline (abbreviation: Bphen), bathocuproin (abbreviation: BCP), 2,9-di(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1, 10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophene-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), ), 7-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 7mDBTPDBq-II) and 6-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 6mDBTPDBq-II), 2-{4-[9,10-di(2-naphthyl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviated as: ZADN), 2-[4'-(9-phenyl-9H-carbazole-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mpPCBPDBq) and other organic compounds containing heteroaromatic rings having dibenzoquinoxaline rings, etc., these materials are preferably used as the main material.

[0212] Among the above-mentioned organic compounds, specific examples of pyridine derivatives, diazine derivatives (including pyrimidine derivatives, pyrazine derivatives, and pyridazine derivatives), triazine derivatives, and furandiazine derivatives, which are organic compounds with high electron transport properties, include 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzo[b]thiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tris[3-(pyridin-3-yl)phenyl]benzene (abbreviation: TmPyPB), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 8-(biphenyl-4-yl)-4-[3-(dibenzo[b]thiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 9-[3'-(dibenzo[b]thiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[3'-(dibenzo[b]thiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 11-[3'-(dibenzo[b]thiophen-4-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 11mDBtBPPnfpr), 11-[3'-(dibenzo[b]thiophen-4-yl)biphenyl-4-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine, 11-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine, 12-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 12PCCzPnfpr), 9-[3’-(9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]naphtho[1’,2’:4,5]furo[2,3-b]pyrazine (abbreviation: 9pmPCBPNfpr), 9-(9’-phenyl-3,3’-bi-9H-carbazol-9-yl)naphtho[1’,2’:4,5]furo[2,3-b]pyrazine (abbreviation: 9PCCzNfpr), 10-(9’-phenyl-3,3’-bi-9H-carbazol-9-yl)naphtho[1’,2’:4,5]furo[2,3-b]pyrazine (abbreviation: 10PCCzNfpr), 9-[3’-(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)biphenyl-3-yl]naphtho[1’,2’:4,5]furo[2,3-b]pyrazine (abbreviation: 9mBnfBPNfpr), 9-{3-[6-(9,9-dimethylfluoren-2-yl)dibenzothiophen-4-yl]phenyl}naphtho[1’,2’:4,5]furo[2,3-b]pyrazine (abbreviation: 9mFDBtPNfpr), 9-[3’-(6-phenyldibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1’,2’:4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr-02), 9-[3-(9’-phenyl-3,3’-bi-9H-carbazol-9-yl)phenyl]naphtho[1’,2’:4,5]furo[2,3-b]pyrazine (abbreviation: 9mPCCzPNfpr), 9-[3’-(2,8-diphenyldibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1’,2’:4,5]furo[2,3-b]pyrazine, 11-{3’-[2,8-diphenyldibenzothiophen-4-yl]biphenyl-3-yl}phenanthro[9’,10’:4,5]furo[2,3-b]pyrazine, 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’-(triphenylene-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 2-(biphenyl-4-yl)-4-phenyl-6-(9,9’-spirobi[9H-fluorene]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridinyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1’:4’,1” - terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), etc., organic compounds containing heteroaromatic rings with diazine rings, etc., and these materials are preferably used as host materials.

[0213] Among the above organic compounds, specific examples of metal complexes as organic compounds with high electron transport properties include: tris(8-hydroxyquinoline)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-hydroxyquinoline)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinoline)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum(III) (abbreviation: BAlq), bis(8-hydroxyquinoline)zinc(II) (abbreviation: Znq); metal complexes having a quinoline ring or a benzoquinoline ring, etc., and these materials are preferably used as host materials.

[0214] In addition, as preferred host materials, polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy), etc. can also be used.

[0215] In addition, organic compounds with high hole-transporting properties, organic compounds with high electron-transporting properties, organic compounds with bipolarity and including a diazine ring or a triazine ring, etc. can be used as host materials such as: 9-phenyl-9'-(4-phenyl-2-quinazolinyl)-3,3'-bi-9H-carbazole (abbreviation: PCCzQz), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviation: BP-mBPIcz(II)Tzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenyl-indolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), 3-{3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]phenyl}-9-phenyl-9H-carbazole (abbreviation: mPCPDBfTzn), 9,9'-[6-(biphenyl 4-yl)-2-phenyl-1,3,5-triazine-4,3”-diyl]bis(9H-carbazole) (abbreviation: Cz-pmCzBPTzn), 3-phenyl-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl)-1,3,5-triazin-2-yl]-9H-carbazole (abbreviation: PDBf-PCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothiophene]-2-phenyl-9H-carbazole (abbreviation: PCzDBtTzn), etc.

[0216] <Hole blocking layer> The hole blocking layer 117 is provided to prevent holes from passing through the second electrode 102 side from the light emitting layer 113. The hole blocking layer 117 preferably uses a material with high electron transport property, low hole transport property, and low HOMO energy level. Preferably, a material is selected from the materials listed below as materials that can be used as the electron transport layer 114, and the HOMO energy level of this material is lower than the HOMO energy level of the material (at least the host material) constituting the light emitting layer. It is preferable to use a material with a HOMO energy level lower by 0.30 eV or more to form the hole blocking layer 117. Note that the hole blocking layer transports electrons and can thus also be regarded as part of the electron transport layer 114.

[0217] <Electron transport layer> The electron transport layer (114, 114a, 114b) is a layer that transports electrons injected from the second electrode 102 and the charge generation layer (106, 106a, 106b) through the electron injection layer (115, 115a, 115b) described later to the light emitting layer (113, 113a, 113b). In addition, in a light emitting device according to one embodiment of the present invention, since the electron transport layer has a stacked structure, the heat resistance is improved. The electron transport material for the electron transport layer (114, 114a, 114b) preferably uses a material having an electron mobility of 1×10 -6 cm 2 / Vs or more when the square root of the electric field strength [V / cm] is 600. In addition, as long as the material has higher electron transport property than hole transport property, materials other than the above can be used. In addition, the electron transport layer (114, 114a, 114b) functions even if it is a single layer, but a stacked structure of two or more layers can also be adopted. Note that since the above-mentioned hybrid material has heat resistance, by performing a photolithography process on the electron transport layer using this hybrid material, the influence of the heat process on the device characteristics can be suppressed.

[0218] <<Electron transport material>> As the electron transport material that can be used for the electron transport layer (114, 114a, 114b), an organic compound with high electron transport property can be used. For example, a heteroaromatic compound can be used. Note that a heteroaromatic compound is a cyclic compound in which the ring contains at least two different elements. Note that the ring structure includes a three-membered ring, a four-membered ring, a five-membered ring, a six-membered ring, etc., and a five-membered ring or a six-membered ring is particularly preferred. As the elements contained in the heteroaromatic compound, in addition to carbon, one or more of nitrogen, oxygen, sulfur, etc. are preferred. A heteroaromatic compound containing nitrogen (nitrogen-containing heteroaromatic compound) is particularly preferred, and an electron transport material such as a nitrogen-containing heteroaromatic compound or a compound having a π-deficient heteroaromatic ring containing the nitrogen-containing heteroaromatic compound is preferably used.

[0219] Note that the electron transport material can be made of a material different from that used for the light-emitting layer. All excitons generated by the recombination of carriers in the light-emitting layer do not necessarily contribute to light emission, and sometimes diffuse into the layer in contact with the light-emitting layer or present in its vicinity. To avoid this phenomenon, the energy level (the lowest singlet excitation level or the lowest triplet excitation level) of the material used for the layer in contact with the light-emitting layer or present in its vicinity is preferably higher than that of the material used for the light-emitting layer. Thus, when the electron transport material is made of a material different from that used for the light-emitting layer, a device with high efficiency can be obtained.

[0220] A heteroaromatic compound is an organic compound containing at least one heteroaromatic ring.

[0221] Note that the heteroaromatic ring includes any one of a pyridine ring, a diazine ring, a triazine ring, an oxazole ring, an oxazole ring, a thiazole ring, etc. In addition, heteroaromatic rings including a pyrimidine ring, a pyrazine ring, a pyridazine ring, etc. are included in the heteroaromatic rings including a diazine ring. In addition, heteroaromatic rings including an oxazole ring include heteroaromatic rings including an imidazole ring, a triazole ring, or an oxadiazole ring.

[0222] The heteroaromatic ring includes a fused heteroaromatic ring having a fused ring structure. Note that examples of the fused heteroaromatic ring include a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a dibenzoquinazoline ring, a phenanthroline ring, a furandiazine ring, a benzimidazole ring, etc.

[0223] Note that, for example, in a heteroaromatic compound containing any one or more of nitrogen, oxygen, sulfur, etc. in addition to carbon, examples of the heteroaromatic compound having a five-membered ring structure include a heteroaromatic compound including an imidazole ring, a heteroaromatic compound including a triazole ring, a heteroaromatic compound including an oxazole ring, a heteroaromatic compound including an oxadiazole ring, a heteroaromatic compound including a thiazole ring, a heteroaromatic compound including a benzimidazole ring, etc.

[0224] For example, in a heteroaromatic compound containing any one or more of nitrogen, oxygen, sulfur, etc. in addition to carbon, examples of the heteroaromatic compound having a six-membered ring structure include a heteroaromatic compound including a pyridine ring, a diazine ring (including a pyrimidine ring, a pyrazine ring, a pyridazine ring, etc.), a triazine ring, an oxazole ring, etc. Note that heteroaromatic compounds having a bipyridine structure, heteroaromatic compounds having a terpyridine structure, etc. are included in the examples of heteroaromatic compounds in which pyridine rings are connected.

[0225] Furthermore, examples of the heteroaromatic compound having a fused ring structure in which a part thereof includes the above six-membered ring structure include a heteroaromatic compound including a fused heteroaromatic ring such as a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a phenanthroline ring, a furandiazine ring (including a structure in which the furan ring of the furandiazine ring is fused with an aromatic ring), a benzimidazole ring, etc.

[0226] As specific examples of the heteroaromatic compounds having the above five-membered ring structure (azole rings (including imidazole rings, triazole rings, oxadiazole rings), oxazole rings, thiazole rings, benzimidazole rings, etc.), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 2,2’,2”-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4’-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), etc. can be cited.

[0227] As specific examples of the above-mentioned heteroaromatic compounds having a six-membered ring structure (including heteroaromatic rings such as pyridine rings, diazine rings, triazine rings, etc.), heteroaromatic compounds including heteroaromatic rings having a pyridine ring such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), etc.; 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 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'-(triphenylene-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluorene]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), mFBPTzn, etc., heteroaromatic compounds including heteroaromatic rings having a triazine ring;4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzo[b][thiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 4,6mCzBP2Pm, 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 4-[3-(dibenzo[b][thiophen-4-yl)phenyl]-8-(naphthalen-2-yl)-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8βN-4mDBtPBfpm), 8BP-4mDBtPBfpm, 9mDBtBPNfpr, 9pmDBtBPNfpr, 3,8-bis[3-(dibenzo[b][thiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzo[b][thiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzo[b][thiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzo[b][thiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzo[b][thiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm), etc., including heteroaromatic compounds having a heteroaromatic ring with a diazine (pyrimidine) ring, etc. Note that aromatic compounds including the above heteroaromatic rings include heteroaromatic compounds including fused heteroaromatic rings.;

[0228] In addition, heteroaromatic compounds containing heteroaromatic rings having a diazine (pyrimidine) ring can be cited, such as 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 6,6'(P-Bqn)2BPy), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), etc.; heteroaromatic compounds containing heteroaromatic rings having a triazine ring, such as 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviation: TmPPPyTz), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tz), 2-[3-(2,6-dimethyl-3-pyridyl)-5-(9-phenanthryl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), etc.

[0229] As specific examples of the heteroaromatic compound (heteroaromatic compound having a condensed ring structure) having a condensed ring structure with a part thereof including the above six-membered ring structure, bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2-[3-(dibenzo[b,d]thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzo[b,d]thiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzo[b,d]thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzo[b,d]thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2mpPCBPDBq and other heteroaromatic compounds including a quinoxaline ring, etc.

[0230] In addition to the above heteroaromatic compounds, the following metal complexes can also be used for the electron transport layer (114, 114a, 114b). Examples of the metal complexes include tris(8-hydroxyquinoline)aluminum(III) (abbreviation: Alq3), Almq3, lithium 8-hydroxyquinolate (abbreviation: Liq), BeBq2, bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum(III) (abbreviation: BAlq), bis(8-hydroxyquinoline)zinc(II) (abbreviation: Znq) and other metal complexes including a quinoline ring or a benzoquinoline ring, bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviation: ZnBTZ) and other metal complexes including an oxazole ring or a thiazole ring, etc.

[0231] In addition, as the electron transport material, polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can also be used.

[0232] In addition, the electron transport layer (114, 114a, 114b) can be a single layer or a laminate of two or more layers containing the above substances.

[0233] <Electron injection layer> The electron injection layer (115, 115a, 115b) is a layer containing a material with high electron injection property. The electron injection layer (115, 115a, 115b) is a layer used to improve the efficiency of injecting electrons from the second electrode 102, and a material with a small difference (0.50 eV or less) between the work function value of the material used for the second electrode 102 and the LUMO energy level value of the material used for the electron injection layer (115, 115a, 115b) is preferably used. Therefore, as the electron injection layer 115, lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), 8-hydroxyquinoline-lithium (abbreviation: Liq), 2-(2-pyridyl)phenol lithium (abbreviation: LiPP), 2-(2-pyridyl)-3-hydroxypyridine(pyridinolato) lithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenol lithium (abbreviation: LiPPP), lithium oxide (LiO x) Alkali metals, alkaline earth metals such as cesium carbonate, or their compounds. In addition, rare earth metals such as erbium fluoride (ErF3) and ytterbium (Yb) can be used. In addition, compounds having a 1,3,4,6,7,8-tetrahydro-2H-pyrimido[1,2-a]pyrimidine skeleton such as 1-(9,9'-spirobi[9H-fluorene]-2-yl)-1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (abbreviation: 2hppSF), 1,1'-(9,9'-spirobi[9H-fluorene]-2,7-diyl)bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) (abbreviation: 2,7hpp2SF), 1,1'-pyridine-2,6-diyl-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) (abbreviation: hpp2Py) can also be used. Note that the electron injection layer (115, 115a, 115b) can be formed by mixing multiple of the above materials or by laminating multiple of the above materials. In addition, an electron compound can also be used for the electron injection layer (115, 115a, 115b). As the electron compound, for example, a substance that adds electrons to a mixed oxide of calcium and aluminum at a high concentration can be cited. In addition, the substances constituting the electron transport layer (114, 114a, 114b) as described above can also be used.

[0234] In addition, a hybrid material obtained by mixing an organic compound and an electron donor can also be used for the electron injection layer (115, 115a, 115b). Such a hybrid material has excellent electron injection properties and electron transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material having excellent performance in transporting the generated electrons. Specifically, for example, an electron transport material (such as a metal complex and a heteroaromatic compound) used for the electron transport layer (114, 114a, 114b) as described above can be used. As the electron donor, any substance that exhibits electron-donating properties to the organic compound can be used. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferably used, and examples include lithium, cesium, magnesium, calcium, erbium, ytterbium, etc. In addition, alkali metal oxides and alkaline earth metal oxides are preferably used, and examples include lithium oxide, calcium oxide, barium oxide, etc. In addition, Lewis bases such as magnesium oxide can also be used. In addition, organic compounds such as tetrathiafulvalene (abbreviation: TTF) can also be used. Or, multiple of these materials can be used in a laminated manner.

[0235] In addition to the above, a hybrid material obtained by mixing an organic compound and a metal can also be used for the electron injection layer (115, 115a, 115b). Note that the organic compound used here preferably has a LUMO energy level of -3.60 eV or higher and -2.30 eV or lower. In addition, a material having a lone pair of electrons is preferably used.

[0236] Therefore, as the organic compound for the above-mentioned hybrid material, a hybrid material formed by mixing the above-mentioned heteroaromatic compound capable of being used for the electron transport layer and a metal can also be used. The heteroaromatic compound is preferably a heteroaromatic compound having a five-membered ring structure (imidazole ring, triazole ring, oxazole ring, oxadiazole ring, thiazole ring, benzimidazole ring, etc.), a heteroaromatic compound having a six-membered ring structure (pyridine ring, diazine ring (including pyrimidine ring, pyrazine ring, pyridazine ring, etc.), triazine ring, bipyridine ring, terpyridine ring, etc.), a heteroaromatic compound having a condensed ring structure (quinoline ring, benzoquinoline ring, quinoxaline ring, dibenzoquinoxaline ring, phenanthroline ring, etc.) in which a part thereof has a six-membered ring structure, etc., which are materials having non-bonding electron pairs. Specific materials have been described above, so the description thereof is omitted here.

[0237] As the metal for the above-mentioned hybrid material, a transition metal belonging to Group 5, Group 7, Group 9 or Group 11 in the periodic table and a material belonging to Group 13 are preferably used. For example, Ag, Cu, Al, or In, etc. can be cited. In addition, at this time, a singly occupied molecular orbital (SOMO) is formed between the organic compound and the transition metal.

[0238] In addition, for example, when amplifying the light obtained from the light-emitting layer 113b, it is preferably formed such that the optical distance between the second electrode 102 and the light-emitting layer 113b is less than 1 / 4 of the wavelength λ of the light presented by the light-emitting layer 113b. In this case, the optical distance can be adjusted by changing the thickness of the electron transport layer 114b or the electron injection layer 115b.

[0239] In addition, as Figure 4F In the light-emitting device shown, by providing a charge generation layer 106 between two organic compound layers (103a, 103b), a structure in which a plurality of organic compound layers are stacked between a pair of electrodes (also referred to as a tandem structure) can be obtained.

[0240] <Charge Generation Layer> The charge generation layer 106 has the following functions: when a voltage is applied between the first electrode 101 (anode) and the second electrode 102 (cathode), the function of injecting electrons into the organic compound layer 103a and injecting holes into the organic compound layer 103b. The charge generation layer 106 can have a structure in which an electron acceptor (acceptor) is added to the hole transport material (also referred to as a P-type layer), and can also have a structure in which an electron donor (donor) is added to the electron transport material (also referred to as an electron injection buffer layer). Alternatively, these two structures can be stacked. Furthermore, an electron relay layer can be provided between the P-type layer and the electron injection buffer layer. Note that by forming the charge generation layer 106 using the above-mentioned materials, an increase in the driving voltage caused when stacking the organic compound layers can be suppressed.

[0241] When the charge generation layer 106 has a structure (P-type layer) in which an electron acceptor is added to a hole transport material for an organic compound, the materials shown in this embodiment can be used as the hole transport material. In addition, as the electron acceptor, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloroquinone, etc. can be cited. In addition, oxides of metals belonging to Groups 4 to 8 in the periodic table can be cited. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, etc. can be cited. In addition, the above acceptor materials can also be used. In addition, a mixed film in which the materials constituting the P-type layer are mixed can be used, or single films containing each material can be laminated.

[0242] When the charge generation layer 106 has a structure (electron injection buffer layer) in which an electron donor is added to an electron transport material, the materials shown in this embodiment can be used as the electron transport material. In addition, as the electron donor, an alkali metal, an alkaline earth metal, a rare earth metal, or a metal belonging to Groups 2 or 13 in the periodic table and their oxides or carbonates can be used. Specifically, lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium oxide (Li2O), cesium carbonate, etc. are preferably used. In addition, compounds of alkali metals such as Liq can also be used. In addition, organic compounds such as tetrathianaphthacene can be used as the electron donor. In addition, organic compounds having a 1,3,4,6,7,8-tetrahydro-2H-pyrimido[1,2-a]pyrimidine skeleton such as 2hppSF, 2,7hpp2SF, and hpp2Py can be used as the electron donor. When these organic compounds are used as the electron donor, when an organic compound containing a heteroaromatic ring having a phenanthroline ring such as bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), etc. is used as the combined electron transport material, the driving voltage of the light-emitting device can be reduced, so it is preferable.

[0243] 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 electron relay layer contains at least a substance having electron-transporting properties and has a function of preventing the interaction between the electron injection buffer layer and the P-type layer and smoothly transferring electrons. The LUMO energy level of the substance having electron-transporting properties contained in the electron relay layer is preferably located between the LUMO energy level of the acceptor substance in the P-type layer and the LUMO energy level of the substance having electron-transporting properties contained in the electron transport layer in contact with the charge generation layer 106. The specific value of the LUMO energy level of the substance having electron-transporting properties in the electron relay layer is preferably -5.00 eV or more, more preferably -5.00 eV or more and -3.00 eV or less. In addition, as the substance having electron-transporting properties in the electron relay layer, a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand is preferably used.

[0244] In addition, from the viewpoint of light extraction efficiency, the charge generation layer 106 preferably has translucency to visible light (specifically, the visible light transmittance of the charge generation layer 106 is 40% or more). In addition, the charge generation layer 106 can function even if its conductivity is lower than that of the first electrode 101 and the second electrode 102.

[0245] Note that although Figure 4F a structure in which two organic compound layers 103 are stacked is shown, a stacked structure of three or more organic compound layers can also be adopted by providing a charge generation layer between different organic compound layers.

[0246] <Cover layer> Note that although not shown in Figures 4A to 4F a cover layer can also be provided on the second electrode 102 of the light-emitting device. For example, a material having a high refractive index can be used for the cover layer. By providing a cover layer on the second electrode 102, the light extraction efficiency of the light emitted from the second electrode 102 can be improved.

[0247] Specific examples of the material that can be used for the cover layer include 5,5'-diphenyl-2,2'-di-5H-[1]benzothieno[3,2-c]carbazole (abbreviation: BisBTc), 4,4',4''-(benzene-1,3,5-triyl)tris(dibenzothiophene) (abbreviation: DBT3P-II), etc.

[0248] <Substrate> The light-emitting device shown in this embodiment can be formed on various substrates. Note that there is no specific limitation on the type of substrate. Examples of such substrates include semiconductor substrates (e.g., single crystal substrates or silicon substrates), SOI substrates, glass substrates, quartz substrates, plastic substrates, metal substrates, stainless steel substrates, substrates containing stainless steel foils, tungsten substrates, substrates containing tungsten foils, flexible substrates, laminated films, papers or base films containing fibrous materials, etc.

[0249] Examples of glass substrates include barium borosilicate glass, aluminosilicate glass, or soda-lime glass, etc. Examples of flexible substrates, laminated films, base films, etc. include plastics represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), synthetic resins such as acrylic resins, polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, polyamide, polyimide, aromatic polyamide, epoxy resin, inorganic vapor deposition films, papers, etc.

[0250] In addition, when manufacturing the light-emitting device shown in this embodiment, vapor-phase methods such as vapor deposition methods, and liquid-phase methods such as spin coating methods and inkjet methods can be used. As vapor deposition methods, physical vapor deposition methods (PVD methods) such as sputtering methods, ion plating methods, ion beam vapor deposition methods, molecular beam vapor deposition methods, vacuum vapor deposition methods, or chemical vapor deposition methods (CVD methods), etc. can be used. In particular, vapor deposition methods (vacuum vapor deposition methods), coating methods (dip coating methods, dye coating methods, bar coating methods, spin coating methods, spraying methods, etc.), printing methods (inkjet methods, screen printing (stencil printing) methods, offset printing (lithography) methods, flexographic printing (letterpress printing) methods, gravure printing methods, microcontact printing methods, etc.) can be used to form layers (hole injection layer 111, hole transport layer 112, light-emitting layer 113, electron transport layer 114, electron injection layer 115) with various functions included in the organic compound layers of the light-emitting device.

[0251] Note that when using the above deposition methods such as coating methods and printing methods, high molecular compounds (oligomers, dendrimers, polymers, etc.), medium molecular compounds (compounds between low molecules and high molecules: molecular weight is above 400 and below 4000), inorganic compounds (quantum dot materials, etc.) can be used. Note that as quantum dot materials, colloidal quantum dot materials, alloy-type quantum dot materials, core-shell (Core Shell)-type quantum dot materials, core-type quantum dot materials, etc. can be used.

[0252] The materials of the respective layers (hole injection layer 111, hole transport layer 112, light-emitting layer 113, electron transport layer 114, electron injection layer 115) that constitute the organic compound layer 103 of the light-emitting device shown in this embodiment are not limited to the materials shown in this embodiment, and materials that can satisfy the functions of the respective layers can be used in combination.

[0253] The structure shown in this embodiment can be used in appropriate combination with the structures shown in other embodiments.

[0254] Embodiment 3 As Figure 5A and Figure 5B shown, a plurality of light-emitting devices 130 are formed on the insulating layer 171 to constitute a display device. In this embodiment, a display device according to one aspect of the present invention will be described in detail.

[0255] The light-emitting device 1000 includes a pixel portion 177 in which a plurality of pixels 178 are arranged in a matrix. The pixel 178 includes a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0256] In this specification and the like, sometimes, for example, the term "sub-pixel 110" is used to describe the common content among the sub-pixel 110R, the sub-pixel 110G, and the sub-pixel 110B. In addition, regarding other components distinguished by letters, sometimes the reference numerals omitting the letters are used to describe the common content among those components.

[0257] The sub-pixel 110R emits red light, the sub-pixel 110G emits green light, and the sub-pixel 110B emits blue light. Thus, an image can be displayed on the pixel portion 177. Note that, in this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are taken as an example for description, and sub-pixels of other colors may also be combined. In addition, the number of sub-pixels is not limited to three, and may be four or more. As four sub-pixels, for example, sub-pixels of four colors, R, G, B, and white (W); sub-pixels of four colors, R, G, B, and Y; and sub-pixels of four colors, R, G, B, and infrared light (IR); etc. can be cited.

[0258] In this specification and the like, sometimes the row direction is denoted as the X direction and the column direction is denoted as the Y direction. The X direction and the Y direction intersect, for example, perpendicularly.

[0259] In Figure 5A the example shown, sub-pixels of different colors are arranged and disposed in the X direction, and sub-pixels of the same color are arranged and disposed in the Y direction. Note that sub-pixels of different colors may also be arranged and disposed in the Y direction, and sub-pixels of the same color may also be arranged and disposed in the X direction.

[0260] A connection portion 140 is provided outside the pixel portion 177, and an area 141 may also be provided. For example, the area 141 is provided between the pixel portion 177 and the connection portion 140. An organic compound layer 103 is provided in the area 141. In addition, a conductive layer 151C is provided in the connection portion 140.

[0261] InFigure 5A and Figure 5B In the example shown in Figure 5A and Figure 5B , the region 141 and the connection part 140 are located on the right side of the pixel part 177, but there is no particular limitation on the positions of the region 141 and the connection part 140. In addition, the region 141 and the connection part 140 may also be one or more.

[0262] Figure 5B is a cross-sectional view example along the Figure 5A dotted line A1 - A2 in Figure 5A . As Figure 5B shown, the light-emitting device 1000 includes an insulating layer 171, a conductive layer 172 on the insulating layer 171, an insulating layer 173 on the insulating layer 171 and 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 are provided with openings reaching the conductive layer 172, and plugs 176 are provided in such a manner as to be embedded in the openings.

[0263] In the pixel part 177, a light-emitting device 130 is provided on the insulating layer 175 and the plugs 176. In addition, a protective layer 135 is provided so as to cover the light-emitting device 130. A substrate 120 is bonded to the protective layer 135 by a resin layer 122. Additionally, it is preferable to provide an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 between adjacent light-emitting devices 130.

[0264] Figure 5B shows a cross-section of a plurality of inorganic insulating layers 125 and a plurality of insulating layers 127, but when looking at the light-emitting device 1000 from above, the inorganic insulating layer 125 and the insulating layer 127 are preferably formed as continuous single layers respectively. In other words, the insulating layer 127 is preferably an insulating layer having an opening part on the first electrode.

[0265] Figure 5B shows the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B as the light-emitting device 130. The light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B can emit light of different colors from each other. For example, the light-emitting device 130R can emit red light, the light-emitting device 130G can emit green light, and the light-emitting device 130B can emit blue light. Additionally, the light-emitting device 130R, the light-emitting device 130G, or the light-emitting device 130B can also emit other visible light or infrared light.

[0266] A display device according to one aspect of the present invention may, for example, have a top emission structure that emits light in a direction opposite to the substrate on which the light-emitting device is formed. Additionally, a display device according to one aspect of the present invention may also have a bottom emission structure.

[0267] As the light-emitting substance contained in the light-emitting device 130, for example, organic compounds or organometallic complexes such as substances that emit fluorescence (fluorescent materials), substances that emit phosphorescence (phosphorescent materials), and substances that exhibit thermally activated delayed fluorescence (Thermally activated delayed fluorescence: TADF materials) can be cited. In addition, inorganic compounds such as quantum dots can also be used.

[0268] The light-emitting device 130R has the structure shown in Embodiment 1. The light-emitting device 130R 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 when the common layer 104 is provided, damage to the organic compound layer 103R during processing can be reduced, so it is preferred. When the common layer 104 is provided, the common layer 104 is preferably an electron injection layer. In addition, when the common layer 104 is not provided, the organic compound layer 103R corresponds to the organic compound layer 103 in Embodiment 1 and Embodiment 2. When the common layer 104 is provided, the laminated structure of the organic compound layer 103R and the common layer 104 corresponds to the organic compound layer 103 in Embodiment 1 and Embodiment 2.

[0269] The light-emitting device 130G has the structure shown in Embodiment 1. The light-emitting device 130G 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. The common layer 104 may or may not be provided, but when the common layer 104 is provided, damage to the organic compound layer 103G during processing can be reduced, so it is preferred. In addition, when the common layer 104 is not provided, the organic compound layer 103G corresponds to the organic compound layer 103 in Embodiment 1 and Embodiment 2. When the common layer 104 is provided, the laminated structure of the organic compound layer 103G and the common layer 104 corresponds to the organic compound layer 103 in Embodiment 1 and Embodiment 2.

[0270] The light-emitting device 130B has the structure as shown in Embodiment 1. The light-emitting device 130B includes a first electrode (pixel electrode) composed of 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. The common layer 104 may or may not be provided. However, when the common layer 104 is provided, damage to the organic compound layer 103B during processing can be reduced, so it is preferred. In addition, when the common layer 104 is not provided, the organic compound layer 103B is equivalent to the organic compound layer 103 in Embodiment 1 and Embodiment 2. When the common layer 104 is provided, the stacked structure of the organic compound layer 103B and the common layer 104 is equivalent to the organic compound layer 103 in Embodiment 1 and Embodiment 2.

[0271] One of the pixel electrode and the common electrode included in the light-emitting device is used as the anode, and the other is used as the cathode. Hereinafter, unless otherwise specified, the description will be made on the premise that the pixel electrode is used as the anode and the common electrode is used as the cathode.

[0272] The organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are independent in island shape for each light-emitting device or for each light-emitting color. By setting the organic compound layer 103 in island shape for each light-emitting device 130, leakage current between adjacent light-emitting devices 130 can also be suppressed in the high-definition display device. Thereby, crosstalk can be prevented to realize a display device with extremely high contrast. In particular, a display device with high current efficiency at low brightness can be realized.

[0273] The island-shaped organic compound layer 103 is formed by depositing an EL film and processing the EL film using a lithography technique.

[0274] In addition, in a display device according to an aspect of the present invention, the first electrode (pixel electrode) of the light-emitting device preferably has a stacked structure. For example, in Figure 5BIn the example shown, 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, in the case where the light-emitting device 1000 has a top-emission structure and the pixel electrode of the light-emitting device 130 is used as an anode, the conductive layer 151 is preferably a layer with a high visible light reflectance, and the conductive layer 152 is preferably a layer having, for example, visible light transmissivity and a large work function. In the case where the light-emitting device 1000 is a top-emission type, the higher the visible light reflectance of the pixel electrode, the higher the extraction efficiency of the light emitted from the organic compound layer 103 can be improved. In addition, when the pixel electrode is used as an anode, the larger the work function of the pixel electrode, the easier it is to inject holes into the organic compound layer 103. Thus, by the pixel electrode of the light-emitting device 130 having a stacked structure of a conductive layer 151 with a high visible light reflectance and a conductive layer 152 with a large work function, the light-emitting device 130 can be a light-emitting device with high light extraction efficiency and low driving voltage.

[0275] In the case where the conductive layer 151 is a layer with a high visible light reflectance, the visible light reflectance of the conductive layer 151 is preferably, for example, 40% or more and 100% or less, or 70% or more and 100% or less. In addition, when the conductive layer 152 is an electrode having visible light transmissivity, the visible light transmittance is preferably, for example, 40% or more.

[0276] Here, in the case where the pixel electrode has a stacked structure of multiple layers, the pixel electrode deteriorates, for example, due to the reaction between the multiple layers. For example, when removing the film formed after forming the pixel electrode by a wet etching method, galvanic corrosion occurs due to the chemical solution contacting the pixel electrode.

[0277] Then, in the light-emitting device 1000 of the present embodiment, an insulating layer 156 is formed on the side surfaces of the conductive layer 151 and the conductive layer 152. Thus, for example, even in the case of using a wet etching method to remove the film formed after forming the pixel electrode including the conductive layer 151 and the conductive layer 152, it is possible to suppress the chemical solution from contacting the conductive layer 151. Therefore, for example, galvanic corrosion occurring in the pixel electrode can be suppressed. Therefore, the light-emitting device 1000 can be manufactured by a method with a high yield, so a low-cost display device can be realized. In addition, defects occurring in the light-emitting device 1000 can be suppressed, so the light-emitting device 1000 can be a display device with high reliability.

[0278] As the conductive layer 151, for example, a metal material can be used. Specifically, for example, 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 obtained by appropriately combining them can also be used.

[0279] As the conductive layer 152, an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. For example, a conductive oxide containing one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, and indium zinc oxide containing silicon is preferably used. In particular, the indium tin oxide containing silicon has a relatively large work function, for example, 4.0 eV or more, so it can be suitably used as the conductive layer 152.

[0280] The conductive layer 151 and the conductive layer 152 may each have a laminated structure including a plurality of layers of different materials. In this case, the conductive layer 151 may include a layer using a material such as a conductive oxide that can be used for the conductive layer 152, and the conductive layer 152 may include a layer using a material such as a metal material that can be used for the conductive layer 151. For example, when the conductive layer 151 has a laminated structure of two or more layers, the layer in contact with the conductive layer 152 may be a layer using a material that can be used for the conductive layer 152.

[0281] Note that the end of the insulating layer 156 may also have a tapered shape. Specifically, when the end of the insulating layer 156 has a tapered shape with a taper angle less than 90°, the coverage of the structure provided along the side surface of the insulating layer 156 can be improved.

[0282] Figure 6A It is a diagram when the conductive layer 151 has a laminated structure including a plurality of layers of different materials. As Figure 6A shown, the conductive layer 151 includes a conductive layer 151a, a conductive layer 151b on the conductive layer 151a, and a conductive layer 151c on the conductive layer 151b. That is, Figure 6A the shown conductive layer 151 has a three-layer laminated structure. Thus, when the conductive layer 151 has a laminated structure of a plurality of layers, it is only necessary to make the visible light reflectance of at least one of the layers constituting the conductive layer 151 higher than the visible light reflectance of the conductive layer 152.

[0283] In Figure 6A the shown example, the conductive layer 151b is sandwiched between the conductive layer 151a and the conductive layer 151c. The conductive layer 151a and the conductive layer 151c can use materials that are less likely to deteriorate compared to the conductive layer 151b. For example, the conductive layer 151a can use a material that is less likely to undergo migration due to contact with the insulating layer 175 compared to the conductive layer 151b. In addition, the conductive layer 151c can use a material that is less likely to be oxidized compared to the conductive layer 151b; and the resistivity of its oxide is lower than that of the oxide of the material used for the conductive layer 151b.

[0284] Thus, by adopting a structure in which the conductive layer 151b is sandwiched between the conductive layer 151a and the conductive layer 151c, the range of material selection for the conductive layer 151b can be expanded. Thereby, for example, the conductive layer 151b can be made into a layer having a higher visible light reflectance than at least one of the conductive layer 151a and the conductive layer 151c. For example, aluminum can be used as the conductive layer 151b. In addition, an aluminum-containing alloy can also be used as the conductive layer 151b. In addition, titanium can be used as the conductive layer 151a. Although the visible light reflectance of titanium is lower than that of aluminum, it is less likely to migrate compared to aluminum even when in contact with the insulating layer 175. And, titanium can be used as the conductive layer 151c. Although the visible light reflectance of titanium is lower than that of aluminum, it is less likely to be oxidized compared to aluminum and the resistivity of its oxide is lower than the resistivity of aluminum oxide.

[0285] In addition, silver or a silver-containing alloy can also be used as the conductive layer 151c. Silver has the characteristic of having a higher visible light reflectance than titanium. Furthermore, silver has the following characteristics: it is less likely to be oxidized compared to aluminum, and the resistivity of silver oxide is lower than the resistivity of aluminum oxide. Thereby, when silver or a silver-containing alloy is used as the conductive layer 151c, the visible light reflectance of the conductive layer 151 can be appropriately increased while suppressing an increase in the resistance of the pixel electrode due to the oxidation of the conductive layer 151b. Here, as the silver-containing alloy, for example, an alloy of silver, palladium, and copper (Ag-Pd-Cu, also denoted as APC) can be used. In addition, when silver or a silver-containing alloy is used as the conductive layer 151c and aluminum is used as the conductive layer 151b, the visible light reflectance of the conductive layer 151c can be increased compared to the visible light reflectance of the conductive layer 151b. Here, silver or a silver-containing alloy can also be used as the conductive layer 151b. In addition, silver or a silver-containing alloy can also be used as the conductive layer 151a.

[0286] On the other hand, the etch processability of a film using titanium is superior to that of a film using silver. Therefore, by using titanium as the conductive layer 151c, the conductive layer 151c can be easily formed. In addition, the etch processability of a film using aluminum is also superior to that of a film using silver.

[0287] Thus, by making the conductive layer 151 have a stacked structure of multiple layers, the characteristics of the display device can be improved. For example, the light-emitting device 1000 can be made into a display device having high light extraction efficiency and high reliability.

[0288] Here, in the case where the light-emitting device 130 adopts a microcavity structure, by using silver or a silver-containing alloy, which is a material with a high visible light reflectance, as the conductive layer 151c, the light extraction efficiency of the light-emitting device 1000 can be appropriately increased.

[0289] As described above, the side surface of the conductive layer 151 preferably has a tapered shape. Specifically, the side surface of the conductive layer 151 preferably has a tapered shape with a taper angle less than 90°. For example, in Figure 6A the conductive layer 151 having the structure shown, it is preferable that the side surface of at least one of the conductive layer 151a, the conductive layer 151b, and the conductive layer 151c has a tapered shape.

[0290] Figure 6A The conductive layer 151 shown can be formed by lithography using a photolithography technique. Specifically, first, a conductive film that will become the conductive layer 151a, a conductive film that will become the conductive layer 151b, and a conductive film that will become the conductive layer 151c are sequentially deposited. Next, a resist mask is formed on the conductive film that will become the conductive layer 151c. Then, for example, the conductive film in the region that does not overlap with the resist mask is removed by an etching method. Here, by processing the conductive film under conditions where the resist mask is more likely to retreat (shrink) compared to the case where the conductive layer 151 is formed with a side surface that does not have a tapered shape (i.e., the side surface is vertical), a conductive layer 151 with a tapered side surface can be formed.

[0291] Here, when processing the conductive film under conditions where the resist mask is likely to retreat (shrink), the conductive film is sometimes likely to be processed in the horizontal direction. In other words, the isotropy of etching is sometimes higher compared to the case where the conductive layer 151 is formed with a vertical side surface.

[0292] In addition, when the conductive layer 151 has a laminated structure of multiple layers made of different materials, the processability of these multiple layers in the horizontal direction is sometimes different. For example, the processability of the conductive layer 151a, the conductive layer 151b, and the conductive layer 151c in the horizontal direction is sometimes different.

[0293] In this case, sometimes after processing the conductive film, as Figure 6A shown, a protrusion is formed with the side surface of the conductive layer 151b located inside the side surfaces of the conductive layer 151a and the conductive layer 151c. As a result, there is a concern that the coverage of the conductive layer 152 over the conductive layer 151 is reduced and disconnection of the conductive layer 152 occurs.

[0294] In view of this, it is preferable to provide the insulating layer 156 as Figure 6A shown. Figure 6A An example is shown in which the insulating layer 156 is provided on the conductive layer 151a in a manner that has a region overlapping with the side surface of the conductive layer 151b. Thereby, disconnection or thinning of the conductive layer 152 due to the protrusion can be suppressed, and thus connection failure or an increase in the driving voltage can be suppressed.

[0295] Note that although Figure 6AA structure is shown in which the entire side surface of the conductive layer 151b is covered with the insulating layer 156, but a part of the side surface of the conductive layer 151b may not be covered with the insulating layer 156. The same applies to the pixel electrode having the structure shown below, and a part of the side surface of the conductive layer 151b may not be covered with the insulating layer 156.

[0296] In the case where the conductive layer 151 has Figure 6A the structure shown, the conductive layer 152 is provided so as to cover the conductive layer 151a, the conductive layer 151b, the conductive layer 151c, and the insulating layer 156 and is electrically connected to the conductive layer 151a, the conductive layer 151b, and the conductive layer 151c. Thus, for example, when removing the film deposited after forming the conductive layer 152 by a wet etching method, the liquid medicine does not come into contact with the conductive layer 151a, the conductive layer 151b, and the conductive layer 151c. Therefore, corrosion occurring in the conductive layer 151a, the conductive layer 151b, and the conductive layer 151c can be suppressed. Therefore, the light-emitting device 1000 can be manufactured by a method with a high yield. In addition, the occurrence of defects can be suppressed, and thus a highly reliable light-emitting device 1000 can be realized.

[0297] Here, as Figure 6A shown, the insulating layer 156 preferably has a curved surface. Thus, for example, disconnection occurring in the conductive layer 152 covering the insulating layer 156 can be suppressed as compared with the case where the side surface of the insulating layer 156 is perpendicular (parallel to the Z direction). In addition, in the case where the side surface of the insulating layer 156 has a tapered shape, specifically, a tapered shape with a taper angle less than 90°, for example, disconnection occurring in the conductive layer 152 covering the insulating layer 156 can be suppressed as compared with the case where the side surface of the insulating layer 156 is perpendicular. Thus, the light-emitting device 1000 can be manufactured by a method with a high yield. In addition, the occurrence of defects can be suppressed, and the light-emitting device 1000 can be made into a highly reliable display device.

[0298] Note that Figure 6A a structure is shown in which the side surface of the conductive layer 151b is located inside the side surfaces of the conductive layer 151a and the conductive layer 151c, but one embodiment of the present invention is not limited thereto. For example, the side surface of the conductive layer 151b may be located outside the side surface of the conductive layer 151a. In addition, the side surface of the conductive layer 151b may be located outside the side surface of the conductive layer 151c.

[0299] Figures 6B to 6D Another structure of the first electrode 101 is shown. Figure 6B Shown in Figure 6A the first electrode 101 of, a structure in which the insulating layer 156 covers not only the side surface of the conductive layer 151b but also the side surfaces of the conductive layer 151a, the conductive layer 151b, and the conductive layer 151c.

[0300] Figure 6C is a structure in which an insulating layer 156 is not provided in the first electrode 101 of Figure 6A .

[0301] Figure 6D is the following structure: In the first electrode 101 of Figure 6A , the conductive layer 151 does not have a laminated structure and the conductive layer 152 has a laminated structure.

[0302] The conductive layer 152a is a layer having, for example, higher adhesion to the conductive layer 152b than the insulating layer 175. As the conductive layer 152a, for example, an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. 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 titanium oxide, zinc titanate, aluminum zinc oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, and indium zinc oxide containing silicon. Thereby, film peeling of the conductive layer 152b can be suppressed. In addition, the conductive layer 152b can be made not to contact the insulating layer 175.

[0303] The conductive layer 152b is a layer having a higher visible light reflectance (for example, reflectance of light at a specified wavelength in the range of 400 nm or more and less than 750 nm) than the conductive layer 151, the conductive layer 152a, and the conductive layer 152c. The visible light reflectance of the conductive layer 152b can be, for example, 70% or more and 100% or less, preferably 80% or more and 100% or less, more preferably 90% or more and 100% or less. In addition, as the conductive layer 152b, for example, a material having a higher visible light reflectance than aluminum can be used. Specifically, for example, silver or a silver-containing alloy can be used as the conductive layer 152b. As the silver-containing alloy, for example, an alloy of silver, palladium, and copper (APC) can be cited. Thereby, the light-emitting device 1000 can be made a light-emitting device with high light extraction efficiency. Note that a metal other than silver can also be used as the conductive layer 152b.

[0304] When the conductive layer 151 and the conductive layer 152 are used as anodes, the conductive layer 152c is preferably a layer having a large work function. The conductive layer 152c is, for example, a layer having a larger work function than the conductive layer 152b. As the conductive layer 152c, for example, the same material as that which can be used for the conductive layer 152a can be used. For example, the same material can be used for the conductive layer 152a and the conductive layer 152c. For example, when indium tin oxide is used for the conductive layer 152a, indium tin oxide can also be used for the conductive layer 152c.

[0305] Note that when the conductive layer 151 and the conductive layer 152 are used as the cathode, the conductive layer 152c is preferably a layer with a small work function. For example, the conductive layer 152c is a layer with a work function smaller than that of the conductive layer 152b.

[0306] In addition, the conductive layer 152c is preferably a layer with a high visible light transmittance (for example, the transmittance of light with a specified wavelength in the range of 400 nm or more and less than 750 nm). For example, the visible light transmittance of the conductive layer 152c is preferably higher than that of the conductive layer 151 and the conductive layer 152b. For example, the visible light transmittance of the conductive layer 152c can be 60% or more and 100% or less, preferably 70% or more and 100% or less, and more preferably 80% or more and 100% or less. Thereby, the light emitted from the organic compound layer 103 and absorbed by the conductive layer 152c can be reduced. In addition, as described above, the conductive layer 152b under the conductive layer 152c can be a layer with a high visible light reflectance. Therefore, the light-emitting device 1000 can be made into a display device with high light extraction efficiency.

[0307] Next, with reference to Figures 10A to 18C An example of the manufacturing method of the light-emitting device 1000 having the Figure 5A shown structure will be described. In the light-emitting device included in the light-emitting device 1000, the organic layer is formed through a manufacturing process including a process using water. By using the light-emitting device according to one aspect of the present invention in the light-emitting device included in the display device according to one aspect of the present invention, a display device including a light-emitting device with a reduced driving voltage and high luminous efficiency can be provided.

[0308] [Example of manufacturing method] The thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by sputtering, chemical vapor deposition (CVD: Chemical Vapor Deposition), vacuum evaporation, pulsed laser deposition (PLD: Pulsed Laser Deposition), or ALD method. As the CVD method, there are plasma-enhanced chemical vapor deposition (PECVD: Plasma Enhanced CVD) method and thermal CVD method. In addition, as one of the thermal CVD methods, there is metal organic chemical vapor deposition (MOCVD: Metal Organic CVD) method.

[0309] In addition, the thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by wet deposition methods such as spin coating, dipping, spraying, inkjet, dispenser, screen printing, offset printing, doctor knife method, slot coating, roll coating, curtain coating, or blade coating.

[0310] In particular, when manufacturing a light-emitting device, vacuum processes such as evaporation methods and solution processes such as spin coating and inkjet printing can be used. As evaporation methods, physical vapor deposition (PVD) methods such as sputtering, ion plating, ion beam evaporation, molecular beam epitaxy, and vacuum evaporation, and chemical vapor deposition (CVD) methods can be cited. In particular, methods such as evaporation (such as vacuum evaporation), coating (dip coating, dye coating, bar coating, spin coating, spraying), and printing (inkjet printing, screen printing (stencil printing), offset printing (lithography), flexography (letterpress printing), gravure printing, or microcontact printing) can be used to form functional layers (such as hole injection layer, hole transport layer, hole blocking layer, light-emitting layer, electron blocking layer, electron transport layer, and electron injection layer) included in the organic compound layer.

[0311] In addition, when processing a thin film constituting a display device, for example, photolithography can be used for processing. Alternatively, nanoimprinting, sandblasting, peeling, etc. can be used to process the thin film. In addition, island-shaped thin films can be directly formed by a deposition method using a masking mask such as a metal mask.

[0312] As photolithography, for example, photolithography can be used. Typically, photolithography has the following two methods. One is a method of forming a resist mask on a thin film to be processed, processing the thin film by etching, for example, and removing the resist mask. The other is a method of forming a photosensitive thin film and then performing exposure and development to process the thin film into a desired shape.

[0313] In photolithography, as the light for exposure, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or light mixed from these lights can be used. In addition, ultraviolet light, KrF laser, ArF laser, etc. can also be used. In addition, immersion exposure technology can be used for exposure. In addition, as the light for exposure, extreme ultraviolet (EUV) light or X-rays can also be used. In addition, instead of the light for exposure, an electron beam can be used. When using extreme ultraviolet light, X-rays, or an electron beam, extremely fine processing can be performed, so it is preferred. In addition, when exposure is performed by scanning a light beam such as an electron beam, a photomask is not required.

[0314] In the etching of a thin film, dry etching, wet etching, sandblasting, etc. can be used.

[0315] First, as Figure 7AAn insulating layer 171 is formed on a substrate (not shown). Next, a conductive layer 172 and a conductive layer 179 are formed on the insulating layer 171, and an insulating layer 173 is formed on the insulating layer 171 so as to cover the conductive layer 172 and the conductive layer 179. Next, an insulating layer 174 is formed on the insulating layer 173, and an insulating layer 175 is formed on the insulating layer 174.

[0316] As the substrate, a substrate having at least heat resistance capable of withstanding the subsequent heat treatment can be used. In the case of using an insulating substrate as the substrate, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like can be used. In addition, a single crystal semiconductor substrate or a polycrystalline semiconductor substrate made of silicon or silicon carbide, a compound semiconductor substrate made of silicon germanium, an SOI substrate, or the like can also be used.

[0317] Next, as Figure 7A shown, an opening reaching the conductive layer 172 is formed in the insulating layer 175, the insulating layer 174, and the insulating layer 173. Next, a plug 176 is formed so as to embed the opening.

[0318] Next, as Figure 7A shown, a conductive film 151f that will later become a conductive layer 151R, a conductive layer 151G, a conductive layer 151B, and a conductive layer 151C is formed on the plug 176 and the insulating layer 175. The conductive film 151f can be formed, for example, by a sputtering method or a vacuum evaporation method. In addition, a metal material can be used as the conductive film 151f, for example.

[0319] Next, as Figure 7A shown, a conductive film 152f that will later become a conductive layer 152R, a conductive layer 152G, a conductive layer 152B, and a conductive layer 152C is formed on the conductive film 151f. The conductive film 152f can be formed, for example, by a sputtering method or a vacuum evaporation method. In addition, a conductive oxide can be used as the conductive film 152f, for example. Alternatively, as the conductive film 152f, a stacked structure of a film using a metal material and a film using a conductive oxide on the film can be employed. For example, as the conductive film 152f, a stacked structure of a film using titanium, silver, or a silver-containing alloy and a film using a conductive oxide on the film can be employed.

[0320] In addition, the conductive film 152f can be formed by ALD. Here, as the conductive film 152f, an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. At this time, by repeating the cycle of introducing a precursor (which is generally sometimes referred to as a precursor or a metal precursor, etc.), purging the precursor, introducing an oxidant (which is generally sometimes referred to as a reactant, a reactant, or a non-metal precursor, etc.), and purging the oxidant as one cycle, the conductive film 152f can be formed. Here, when forming an oxide film containing multiple metals such as indium tin oxide as the conductive film 152f, the metal composition can be controlled by changing the number of cycles according to the type of precursor.

[0321] For example, in the case of depositing an indium tin oxide film as the conductive film 152f, after introducing a precursor containing indium, the precursor is purged and an oxidant is introduced to form an In-O film. Next, after introducing a precursor containing tin, the precursor is purged and an oxidant is introduced to form a Sn-O film. Here, by making the number of cycles when forming the In-O film more than the number of cycles when forming the Sn-O film, the number of In atoms contained in the conductive film 152f can be made more than the number of Sn atoms.

[0322] In addition, for example, in the case of depositing a zinc oxide film as the conductive film 152f, a Zn-O film is formed by the above process. In addition, for example, in the case of depositing an aluminum zinc oxide film as the conductive film 152f, a Zn-O film and an Al-O film are formed by the above process. In addition, for example, in the case of depositing a titanium oxide film as the conductive film 152f, a Ti-O film is formed by the above process. In addition, for example, in the case of depositing an indium tin oxide film containing silicon as the conductive film 152f, an In-O film, a Sn-O film, and a Si-O film are formed by the above process. In addition, for example, in the case of depositing a zinc oxide film containing gallium, a Ga-O film and a Zn-O film are formed by the above process.

[0323] As a precursor containing indium, for example, triethylindium, trimethylindium, or [1,1,1-trimethyl-N-(trimethylsilyl)amide]-indium can be used. As a precursor containing tin, for example, tin chloride or tin(IV) bis(dimethylamide) can be used. As a precursor containing zinc, for example, diethylzinc or dimethylzinc can be used. As a precursor containing gallium, for example, triethylgallium can be used. As a precursor containing titanium, for example, titanium chloride, titanium(IV) bis(dimethylamide), or tetraisopropyl titanate can be used. As a precursor containing aluminum, for example, aluminum chloride or trimethylaluminum can be used. As a precursor containing silicon, for example, trisilylamine, bis(diethylamino)silane, tris(dimethylamino)silane, bis(tert-butylamino)silane, or bis(ethylmethylamino)silane can be used. In addition, as the oxidant, water vapor, oxygen plasma, or ozone gas can be used.

[0324] Next, as shown in Figure 7A FIG. Figure 7A , a resist mask 191 is formed on the conductive film 151f and the conductive film 152f. The resist mask 191 can be formed by applying a photosensitive material (photoresist) and performing exposure and development.

[0325] Next, as shown in Figure 7B FIG. Figure 7B , for example, by using an etching method, specifically, for example, by using a dry etching method, the conductive film 151f and the conductive film 152f in the regions not overlapping with the resist mask 191 are removed to form pixel electrodes including the conductive layer 151 and the conductive layer 152. Note that, when the conductive film 151f includes a layer using a conductive oxide such as indium tin oxide, the layer can also be removed by a wet etching method. Thus, the conductive layer 151 and the conductive layer 152 are formed. Note that, for example, when a part of the conductive film 151f is removed by a dry etching method, recesses may be formed in the region of the insulating layer 175 that does not overlap with the conductive layer 151.

[0326] Note that, after processing the conductive film 152f by lithography to form the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the conductive layer 152C, the conductive film 151f can be processed using the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the conductive layer 152C as masks. Specifically, for example, after forming the resist mask, a part of the conductive film 152f is removed by an etching method. For example, the conductive film 152f can be removed by a wet etching method. Note that the conductive film 152f can also be removed by a dry etching method. Then, it is preferable to remove the conductive film 151f by a wet etching method.

[0327] Here, it is preferable to perform a hydrophobization treatment on the conductive layer 152. By the hydrophobization treatment, the surface state of the object to be treated can be changed from hydrophilic to hydrophobic, or the hydrophobicity of the surface of the object to be treated can be improved. By performing the hydrophobization treatment on the conductive layer 152, the adhesion between the conductive layer 152 and the organic compound layer 103 to be formed in a later process can be improved to suppress film peeling. Note that the hydrophobization treatment may not be performed.

[0328] Next, as shown in Figure 7C FIG. Figure 7C , the resist mask 191 is removed. The resist mask 191 can be removed, for example, by ashing using oxygen plasma. Alternatively, oxygen gas and CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or a Group 18 element such as He can also be used. Alternatively, the resist mask 191 can be removed by wet etching.

[0329] Next, as shown in Figure 7DAs shown, an insulating film 156f that will later become insulating layers 156R, 156G, 156B, and 156C is formed on conductive layer 151R and conductive layer 152R, conductive layer 151G and conductive layer 152G, conductive layer 151B and conductive layer 152B, conductive layer 151C and conductive layer 152C, and insulating layer 175. The insulating film 156f can be formed, for example, by CVD method, ALD method, sputtering method, or vacuum evaporation method.

[0330] The insulating film 156f can use inorganic materials. As the insulating film 156f, for example, inorganic insulating films such as oxide insulating film, nitride insulating film, oxynitride insulating film, or nitrogen oxide insulating film can be used. For example, as the insulating film 156f, an oxide insulating film, nitride insulating film, oxynitride insulating film, or nitrogen oxide insulating film containing silicon can be used. For example, silicon oxynitride can be used as the insulating film 156f.

[0331] Next, as Figure 7E shown, the insulating film 156f is processed to form insulating layers 156R, 156G, 156B, and 156C. For example, by etching the top surface of the insulating film 156f substantially uniformly, the insulating layer 156 can be formed. The process of etching uniformly like this for planarization is also called etch-back process. In addition, the insulating layer 156 can also be formed using lithography technology.

[0332] Next, as Figure 8A shown, an organic compound film 103Rf that will later become the organic compound layer 103R is formed on conductive layer 152R, conductive layer 152G, conductive layer 152B, insulating layer 156R, insulating layer 156G, insulating layer 156B, and insulating layer 175.

[0333] As Figure 8A shown, the organic compound film 103Rf is not formed on the conductive layer 152C. For example, by using a mask for defining the deposition range (also called a region mask or a rough metal mask, etc. to distinguish it from a high-precision metal mask), the organic compound film 103Rf can be deposited only in the desired region. By adopting a deposition process using a region mask and a processing process using a resist mask, a light-emitting device can be manufactured with a relatively simple process.

[0334] The organic compound film 103Rf can be formed, for example, by evaporation method, specifically by vacuum evaporation method. In addition, the organic compound film 103Rf can also be formed by methods such as transfer method, printing method, inkjet method, coating method, etc.

[0335] Next, as Figure 8AAs shown, a sacrificial film 158Rf that will later become a sacrificial layer 158R and a mask film 159Rf that will later become a mask layer 159R are sequentially formed on an organic compound film 103Rf, a conductive layer 152C, and an insulating layer 175.

[0336] Note that, in the present embodiment, an example in which the mask film is composed of a two-layer structure of a sacrificial film 158Rf and a mask film 159Rf is shown, but the mask film may have a single-layer structure or a laminated structure of three or more layers. Further, in the present specification and the like, the mask layer may also be referred to as a sacrificial layer.

[0337] By providing a sacrificial layer on the organic compound film 103Rf, damage to the organic compound film 103Rf in the manufacturing process of the display device can be reduced, and the reliability of the light-emitting device can be improved.

[0338] As the sacrificial film 158Rf, a film with high resistance to the processing conditions of the organic compound film 103Rf is used, specifically, a film with a large etching selectivity ratio with respect to the organic compound film 103Rf. As the mask film 159Rf, a film with a large etching selectivity ratio with respect to the sacrificial film 158Rf is used.

[0339] In addition, the sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the heat-resistant temperature of the organic compound film 103Rf. The substrate temperature when forming the sacrificial film 158Rf and the mask film 159Rf is typically 200°C or lower, preferably 150°C or lower, more preferably 120°C or lower, further preferably 100°C or lower, and still more preferably 80°C or lower.

[0340] As the sacrificial film 158Rf and the mask film 159Rf, a film that can be removed by wet etching is preferably used. By using wet etching, damage to the organic compound film 103Rf during the processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced compared to the case of using dry etching.

[0341] The sacrificial film 158Rf and the mask film 159Rf can be formed, for example, by sputtering, ALD (thermal ALD, PEALD), CVD, or vacuum evaporation. In addition, they can also be formed by the above-mentioned wet deposition methods.

[0342] The sacrificial film 158Rf formed in contact with the organic compound film 103Rf is preferably formed by a forming method that causes less damage to the organic compound film 103Rf compared to when forming the mask film 159Rf. For example, compared to sputtering, it is more preferable to use ALD or vacuum evaporation to form the sacrificial film 158Rf.

[0343] As the sacrificial film 158Rf and the mask film 159Rf, for example, one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, and an inorganic insulating film can be used.

[0344] As the sacrificial film 158Rf and the mask film 159Rf, for example, metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metal materials can be used respectively. Low melting point materials such as aluminum or silver are particularly preferably used. By using a metal material capable of shielding ultraviolet rays as one or both of the sacrificial film 158Rf and the mask film 159Rf, it is possible to suppress the ultraviolet rays from irradiating the organic compound film 103Rf and suppress the deterioration of the organic compound film 103Rf, so it is preferred.

[0345] In addition, as the sacrificial film 158Rf and the mask film 159Rf, metal oxides such as In-Ga-Zn oxide, indium oxide, In-Zn oxide, In-Sn oxide, indium-titanium oxide (In-Ti oxide), indium-tin-zinc oxide (In-Sn-Zn oxide), indium-titanium-zinc oxide (In-Ti-Zn oxide), indium-gallium-tin-zinc oxide (In-Ga-Sn-Zn oxide), or indium tin oxide containing silicon can be used respectively.

[0346] Note that the above gallium can also be replaced with an element M (M is one or more of aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium).

[0347] In addition, as the sacrificial film and the mask film, a film containing a material having light-shielding properties, particularly ultraviolet light-shielding properties, is preferably used. As the light-shielding material, various materials such as a metal, an insulator, a semiconductor, and a semimetal having ultraviolet light-shielding properties can be used. Since a part or all of the sacrificial film and the mask film will be removed in a later process, the sacrificial film and the mask film are preferably films that can be processed by etching, and particularly preferably films with good processability.

[0348] When a semiconductor material such as silicon or germanium is used as the sacrificial film and the mask film, for example, the affinity of the material for the semiconductor manufacturing process is high, so it is preferred. Alternatively, an oxide or nitride of the above semiconductor material can be used. Alternatively, a non-metal material such as carbon or its compound can be used. In addition, a metal such as titanium, tantalum, tungsten, chromium, aluminum, or an alloy containing one or more of them can be used. In addition, an oxide containing the above metal such as titanium oxide or chromium oxide or a nitride such as titanium nitride, chromium nitride, or tantalum nitride can be used.

[0349] In addition, by using a film made of a material having ultraviolet light-shielding properties as a sacrificial film or a mask film, it is possible to suppress, for example, ultraviolet light from irradiating the organic compound layer during the exposure process. By suppressing damage to the organic compound layer caused by ultraviolet light, the reliability of the light-emitting device can be improved.

[0350] Note that the same effect is produced when the film containing the material having ultraviolet light-shielding properties is used as the material for the inorganic insulating film 125f described later.

[0351] In addition, various inorganic insulating films can be used as the sacrificial film 158Rf and the mask film 159Rf, respectively. In particular, an oxide insulating film has a higher adhesion to the organic compound film 103Rf than a nitride insulating film, so it is preferred. For example, inorganic insulating materials such as alumina, hafnium oxide, or silicon oxide can be used for the sacrificial film 158Rf and the mask film 159Rf. As the sacrificial film 158Rf and the mask film 159Rf, an alumina film can be formed by ALD method, for example. By using the ALD method, damage to the substrate (especially to the organic compound layer) can be reduced, so it is preferred.

[0352] For example, an inorganic insulating film (e.g., an alumina film) formed by ALD method can be used as the sacrificial film 158Rf, and an inorganic film (e.g., In-Ga-Zn oxide film, aluminum film, or tungsten film) formed by sputtering method can be used as the mask film 159Rf.

[0353] In addition, the same inorganic insulating film can be used for both the sacrificial layer 158Rf and the inorganic insulating layer 125 to be formed later. For example, an alumina film formed by ALD method can be used for both the sacrificial layer 158Rf and the inorganic insulating layer 125. Here, the sacrificial layer 158Rf and the inorganic insulating layer 125 can be deposited under the same deposition conditions or different deposition conditions. For example, by depositing the sacrificial film 158Rf under the same conditions as the inorganic insulating layer 125, an insulating layer with high barrier properties against at least one of water and oxygen can be formed as the sacrificial film 158Rf. On the other hand, since most or all of the sacrificial film 158Rf will be removed in later processes, it is preferably easy to process. Therefore, the sacrificial layer 158Rf is preferably deposited under conditions with a lower substrate temperature than the inorganic insulating layer 125 during deposition.

[0354] As one or both of the sacrificial film 158Rf and the mask film 159Rf, an organic material may also be used. For example, as the organic material, a material that can be dissolved in a solvent that is at least chemically stable to the film located at the uppermost part of the organic compound film 103Rf may be used. In particular, a material that can be dissolved in water or alcohol can be appropriately used. When depositing the above material, preferably, the material is applied by a wet deposition method in a state where the material is dissolved in a solvent such as water or alcohol, and then a heat treatment for evaporating the solvent is performed. At this time, the heat treatment is preferably performed in a reduced-pressure atmosphere, whereby the solvent can be removed at a low temperature and in a short time, and the thermal damage to the organic compound film 103Rf can be reduced.

[0355] As the sacrificial film 158Rf and the mask film 159Rf, organic resins such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerol, pullulan, water-soluble cellulose, a polyamide resin soluble in alcohol, or a fluororesin such as a perfluoropolymer may also be used.

[0356] For example, as the sacrificial film 158Rf, an organic film (for example, a PVA film) formed by any one of vapor deposition and the above wet deposition method may be used, and as the mask film 159Rf, an inorganic film (for example, a silicon nitride film) formed by sputtering may be used.

[0357] Next, as Figure 8A shown, a resist mask 190R is formed on the mask film 159Rf. The resist mask 190R can be formed by applying a photosensitive material (photoresist) and performing exposure and development.

[0358] The resist mask 190R can use a positive resist material or a negative resist material.

[0359] The resist mask 190R is provided at a position overlapping with the conductive layer 152R. The resist mask 190R is preferably also provided at a position overlapping with the conductive layer 152C. Thereby, damage to the conductive layer 152C during the manufacturing process of the display device can be suppressed. Note that the resist mask 190R may not be provided on the conductive layer 152C. In addition, as Figure 8A shown in the cross-sectional view between B1 and B2, the resist mask 190R is preferably provided so as to cover the end portion of the organic compound film 103Rf to the end portion of the conductive layer 152C (the end portion on the organic compound film 103Rf side).

[0360] Next, as Figure 8BAs shown, a part of the mask film 159Rf is removed using the resist mask 190R, thereby forming the mask layer 159R. The mask layer 159R remains on the conductive layer 152R and the conductive layer 152C. Then, the resist mask 190R is removed. Next, the mask layer 159R is used as a mask (also referred to as a hard mask) to remove a part of the sacrificial film 158Rf, thereby forming the sacrificial layer 158R.

[0361] The sacrificial film 158Rf and the mask film 159Rf can be processed by a wet etching method or a dry etching method, respectively. The processing of the sacrificial film 158Rf and the mask film 159Rf is preferably performed by isotropic etching.

[0362] By using the wet etching method, the damage to the organic compound film 103Rf during the processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced compared to the case of using the dry etching method. When using the wet etching method, for example, it is preferable to use a developing solution, an aqueous solution of tetramethylammonium hydroxide (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a liquid medicine such as a mixed liquid thereof.

[0363] When processing the mask film 159Rf, the organic compound film 103Rf is not exposed, so the range of choices for the processing method is wider compared to the case of processing the sacrificial film 158Rf. Specifically, when processing the mask film 159Rf, even if an oxygen-containing gas is used as the etching gas, the deterioration of the organic compound film 103Rf can be suppressed.

[0364] In addition, when using the dry etching method in the processing of the sacrificial film 158Rf, the deterioration of the organic compound film 103Rf can be suppressed by not using an oxygen-containing gas as the etching gas. In the case of using the dry etching method, for example, it is preferable to use a gas containing CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or a Group 18 element such as He as the etching gas.

[0365] For example, when using an aluminum oxide film formed by the ALD method as the sacrificial film 158Rf, a part of the sacrificial film 158Rf can be removed by dry etching using CHF3 and He or CHF3, He, and CH4. In addition, when using an In-Ga-Zn oxide film formed by sputtering as the mask film 159Rf, a part of the mask film 159Rf can be removed by wet etching using dilute phosphoric acid. Alternatively, a part of the mask film 159Rf can be removed by dry etching using CH4 and Ar. Alternatively, a part of the mask film 159Rf can be removed by wet etching using dilute phosphoric acid. In addition, in the case of using a tungsten film formed by sputtering as the mask film 159Rf, a part of the mask film 159Rf can be removed by dry etching using SF6, CF4, and O2 or CF4, Cl2, and O2.

[0366] The resist mask 190R can be removed by the same method as the resist mask 191. The resist mask 190R can be removed, for example, by ashing using oxygen plasma. Alternatively, oxygen gas and CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or a Group 18 element such as He can also be used. Alternatively, the resist mask 190R can be removed by wet etching. At this time, since the sacrificial film 158Rf is located on the outermost surface and the organic compound film 103Rf is not exposed, damage to the organic compound film 103Rf can be suppressed in the process of removing the resist mask 190R. In addition, the range of options for the method of removing the resist mask 190R can be expanded.

[0367] Next, as Figure 8B shown, the organic compound film 103Rf is processed to form the organic compound layer 103R. For example, the mask layer 159R and the sacrificial layer 158R are used as hard masks to remove a part of the organic compound film 103Rf to form the organic compound layer 103R.

[0368] Thereby, as Figure 8B shown, a stacked structure of the organic compound layer 103R, the sacrificial layer 158R, and the mask layer 159R remains on the conductive layer 152R. In addition, the conductive layer 152G and the conductive layer 152B are exposed.

[0369] Figure 8B An example is shown in which the end of the organic compound layer 103R is located inside the end of the conductive layer 152R. By adopting this structure, miniaturization of the pixel can be achieved, and a high-definition display can be manufactured. Note that although not shown in Figure 8B , sometimes recesses are formed in the region of the insulating layer 175 that does not overlap with the organic compound layer 103R by the above etching process.

[0370] As described above, the resist mask 190R is preferably provided so as to cover the end of the organic compound layer 103R to the end of the conductive layer 152C (the end on the organic compound layer 103R side) between B1 - B2. Thereby, as Figure 8B shown, the sacrificial layer 158R and the mask layer 159R are provided so as to cover the end of the organic compound layer 103R to the end of the conductive layer 152C (the end on the organic compound layer 103R side) between the dotted lines B1 - B2. Therefore, for example, exposure of the insulating layer 175 between B1 - B2 can be suppressed. Thereby, removal of a part of the insulating layer 175, the insulating layer 174, and the insulating layer 173 by etching or the like, resulting in exposure of the conductive layer 179, can be suppressed. Therefore, unintentional electrical connection of the conductive layer 179 to other conductive layers can be suppressed. For example, a short circuit between the conductive layer 179 and the common electrode 155 to be formed in a later process can be suppressed.

[0371] Preferably, the organic compound film 103Rf is processed using anisotropic etching. Particularly preferably, anisotropic dry etching is used. Alternatively, wet etching may also be used.

[0372] When using the dry etching method, by not using an oxygen-containing gas as the etching gas, deterioration of the organic compound film 103Rf can be suppressed.

[0373] In addition, an oxygen-containing gas may also be used as the etching gas. When the etching gas contains oxygen, the etching rate can be increased. Therefore, etching can be performed under low-power conditions while maintaining a sufficient etching rate. Therefore, damage to the organic compound film 103Rf can be suppressed. Also, defects such as adhesion of reaction products generated during etching can be suppressed.

[0374] When using the dry etching method, for example, it is preferable to use a gas containing one or more of H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, and a Group 18 element such as He or Ar as the etching gas. Alternatively, it is preferable to use a gas containing one or more of the above gases and oxygen as the etching gas. Alternatively, oxygen gas may also be used as the etching gas. Specifically, for example, a gas containing H2 and Ar or a gas containing CF4 and He may be used as the etching gas. In addition, for example, a gas containing CF4, He, and oxygen may be used as the etching gas. Also, for example, a gas containing H2 and Ar and an oxygen-containing gas may be used as the etching gas.

[0375] As described above, in one aspect of the present invention, a mask layer 159R is formed by forming a resist mask 190R on the mask film 159Rf and removing a part of the mask film 159Rf using the resist mask 190R. Then, an organic compound layer 103R is formed by using the mask layer 159R as a mask to remove a part of the organic compound film 103Rf. Therefore, it can be said that the organic compound layer 103R is formed by processing the organic compound film 103Rf using lithography. In addition, a part of the organic compound film 103Rf may be removed using the resist mask 190R. Then, the resist mask 190R may also be removed.

[0376] Next, for example, it is preferable to perform a hydrophobization treatment on the conductive layer 152G. When processing the organic compound film 103Rf, for example, the surface state of the conductive layer 152G sometimes becomes hydrophilic. By performing the hydrophobization treatment on the conductive layer 152G, for example, the adhesion between the conductive layer 152G and the layer (here, the organic compound layer 103G) to be formed in a later process can be improved to suppress film peeling. Note that the hydrophobization treatment may not be performed.

[0377] Next, as Figure 9AAs shown, an organic compound film 103Gf that will later become the organic compound layer 103G is formed on the conductive layer 152G, the conductive layer 152B, the insulating layer 156R, the insulating layer 156G, the insulating layer 156B, the mask layer 159R, and the insulating layer 175.

[0378] The organic compound film 103Gf can be formed in the same manner as the method that can be used when forming the organic compound film 103Rf. Additionally, the organic compound film 103Gf can have the same structure as the organic compound film 103Rf.

[0379] Next, as Figure 9A shown, a sacrificial film 158Gf that will later become the sacrificial layer 158G and a mask film 159Gf that will later become the mask layer 159G are sequentially formed on the organic compound film 103Gf and the mask layer 159R. Then, a resist mask 190G is formed. The materials and formation methods of the sacrificial film 158Gf and the mask film 159Gf are the same as the conditions that can be used for the sacrificial film 158Rf and the mask film 159Rf. The materials and formation methods of the resist mask 190G are the same as the conditions that can be applied to the resist mask 190R.

[0380] The resist mask 190G is provided at a position overlapping with the conductive layer 152G.

[0381] Next, as Figure 9B shown, a part of the mask film 159Gf is removed using the resist mask 190G, thereby forming the mask layer 159G. The mask layer 159G remains on the conductive layer 152G. Then, the resist mask 190G is removed. Next, a part of the sacrificial film 158Gf is removed using the mask layer 159G as a mask to form the sacrificial layer 158G. Next, the organic compound film 103Gf is processed to form the organic compound layer 103G. For example, a part of the organic compound film 103Gf is removed using the mask layer 159G and the sacrificial layer 158G as a hard mask to form the organic compound layer 103G.

[0382] Thus, as Figure 9B shown, a stacked structure of the organic compound layer 103G, the sacrificial layer 158G, and the mask layer 159G remains on the conductive layer 152G. In addition, the mask layer 159R and the conductive layer 152B are exposed.

[0383] Next, for example, it is preferable to perform a hydrophobization treatment on the conductive layer 152B. When processing the organic compound film 103Gf, for example, the surface state of the conductive layer 152B sometimes becomes hydrophilic. By performing the hydrophobization treatment on the conductive layer 152B, for example, the adhesion between the conductive layer 152B and the layer (here, the organic compound layer 103B) that will be formed in the subsequent process can be improved to suppress film peeling. Note that the hydrophobization treatment may not be performed.

[0384] Next, as Figure 9C shown, an organic compound film 103Bf that will later become the organic compound layer 103B is formed on the conductive layer 152B, the insulating layer 156R, the insulating layer 156G, the insulating layer 156B, the mask layer 159R, the mask layer 159G, and the insulating layer 175.

[0385] The organic compound film 103Bf can be formed in the same manner as the method that can be used when forming the organic compound film 103Rf. Additionally, the organic compound film 103Bf can have the same structure as the organic compound film 103Rf.

[0386] Next, as Figure 9C shown, a sacrificial film 158Bf that will later become the sacrificial layer 158B and a mask film 159Bf that will later become the mask layer 159B are sequentially formed on the organic compound film 103Bf and the mask layer 159R. Then, a resist mask 190B is formed. The materials and formation methods of the sacrificial film 158Bf and the mask film 159Bf are the same as the conditions that can be used for the sacrificial film 158Rf and the mask film 159Rf. The materials and formation methods of the resist mask 190B are the same as the conditions that can be applied to the resist mask 190R.

[0387] The resist mask 190B is provided at a position overlapping with the conductive layer 152B.

[0388] Next, as Figure 9D shown, a part of the mask film 159Bf is removed using the resist mask 190B, thereby forming the mask layer 159B. The mask layer 159B remains on the conductive layer 152B. Then, the resist mask 190B is removed. Next, a part of the sacrificial film 158Bf is removed using the mask layer 159B as a mask to form the sacrificial layer 158B. Next, the organic compound film 103Bf is processed to form the organic compound layer 103B. For example, a part of the organic compound film 103Bf is removed using the mask layer 159B and the sacrificial layer 158B as hard masks to form the organic compound layer 103B.

[0389] Thus, as Figure 9D shown, a stacked structure of the organic compound layer 103B, the sacrificial layer 158B, and the mask layer 159B remains on the conductive layer 152B. Additionally, the mask layer 159R and the mask layer 159G are exposed.

[0390] Note that the sides of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are each preferably perpendicular or substantially perpendicular to the formation surface. For example, the angle formed by the formation surface and these sides is preferably 60 degrees or more and 90 degrees or less.

[0391] As described above, the distance between two adjacent organic compound layers among the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B formed by lithography can be reduced to less than 8 μm, less than 5 μm, less than 3 μm, less than 2 μm, or less than 1 μm. Here, for example, this distance can be defined according to the distance between the opposing ends of two adjacent organic compound layers among the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B. In this way, by reducing the distance between the island-shaped organic compound layers, a display device with high clarity and a large aperture ratio can be provided. In addition, the distance between the first electrodes of adjacent light-emitting devices can also be reduced, for example, to less than 10 μm, less than 8 μm, less than 5 μm, less than 3 μm, or less than 2 μm. In addition, the distance between the first electrodes of adjacent light-emitting devices is preferably 2 μm or more and 5 μm or less.

[0392] Next, as Figure 10A shown, it is preferable to remove the mask layer 159R, the mask layer 159G, and the mask layer 159B. Depending on subsequent processes, the sacrificial layer 158R, the sacrificial layer 158G, the sacrificial layer 158B, the mask layer 159R, the mask layer 159G, and the mask layer 159B may remain in the display device. By removing the mask layer 159R, the mask layer 159G, and the mask layer 159B at this stage, it is possible to prevent the mask layer 159R, the mask layer 159G, and the mask layer 159B from remaining in the display device. For example, in the case where a conductive material is used for the mask layer 159R, the mask layer 159G, and the mask layer 159B, by removing the mask layer 159R, the mask layer 159G, and the mask layer 159B in advance, it is possible to prevent leakage current generation and capacitance formation caused by the remaining mask layer 159R, the mask layer 159G, and the mask layer 159B.

[0393] Note that although the case of removing the mask layer 159R, the mask layer 159G, and the mask layer 159B is described as an example in this embodiment, it is also possible not to remove the mask layer 159R, the mask layer 159G, and the mask layer 159B. For example, when the mask layer 159R, the mask layer 159G, and the mask layer 159B contain the above-mentioned material having ultraviolet light-shielding properties, it is preferable to enter the next process without removing the above mask layer to protect the organic compound layer from ultraviolet light.

[0394] As the mask layer removal process, the same method as the mask film processing process can be used. By using the wet etching method, compared with the case of using the dry etching method, the damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B during the removal of the mask layer can be reduced.

[0395] Alternatively, the mask layer can also be removed by dissolving it in a solvent such as water or alcohol. Examples of the alcohol include ethanol, methanol, isopropyl alcohol (IPA), or glycerol.

[0396] After removing the mask layer, a drying process can also be performed to remove the water contained in the organic compound layers 103R, 103G, and 103B and the water adsorbed on the surfaces of the organic compound layers 103R, 103G, and 103B. For example, a heat treatment can be performed in an inert gas atmosphere or a reduced-pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. By using a reduced-pressure atmosphere, drying can be performed at a lower temperature, so it is preferred.

[0397] Next, as Figure 10B shown, an inorganic insulating film 125f that will later become the inorganic insulating layer 125 is formed so as to cover the organic compound layers 103R, 103G, 103B, the sacrificial layers 158R, 158G, and 158B.

[0398] As described later, an insulating film that will later become the insulating layer 127 is formed in contact with the top surface of the inorganic insulating film 125f. Therefore, the top surface of the inorganic insulating film 125f preferably has high affinity with the material for this insulating film (for example, a photosensitive resin composition containing an acrylic resin). To improve this affinity, surface treatment can also be performed to hydrophobize (or increase its hydrophobicity) the top surface of the inorganic insulating film 125f. For example, it is preferred to perform treatment using a silylating agent such as hexamethyldisilazane (HMDS). By hydrophobizing the top surface of the inorganic insulating film 125f in this way, the insulating film 127f can be formed with high adhesion. In addition, as the surface treatment, the above-mentioned hydrophobization treatment can also be performed.

[0399] Next, as Figure 10C shown, an insulating film 127f that will later become the insulating layer 127 is formed on the inorganic insulating film 125f.

[0400] The inorganic insulating film 125f and the insulating film 127f are preferably deposited by a formation method that causes less damage to the organic compound layers 103R, 103G, and 103B. In particular, since the inorganic insulating film 125f is formed in contact with the sides of the organic compound layers 103R, 103G, and 103B, the inorganic insulating film 125f is preferably deposited by a formation method that causes less damage to the organic compound layers 103R, 103G, and 103B than when depositing the insulating film 127f.

[0401] In addition, the inorganic insulating film 125f and the insulating film 127f are each formed at a temperature lower than the heat-resistant temperature of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B. By increasing the substrate temperature during deposition, an inorganic insulating film 125f with a low impurity concentration and high barrier properties against at least one of water and oxygen can be formed even when its thickness is thin.

[0402] The substrate temperature when forming the inorganic insulating film 125f and the insulating film 127f is each preferably 60°C or higher, 80°C or higher, 100°C or higher, or 120°C or higher and 200°C or lower, 180°C or lower, 160°C or lower, 150°C or lower, or 140°C or lower.

[0403] As the inorganic insulating film 125f, it is preferable to form an insulating film with a thickness of 3 nm or more, 5 nm or more, or 10 nm or more and 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less within the above substrate temperature range.

[0404] The inorganic insulating film 125f is preferably formed by, for example, the ALD method. By using the ALD method, deposition damage can be reduced, and a film with high coverage can be deposited, so it is preferable. As the inorganic insulating film 125f, it is preferable to form an alumina film by the ALD method, for example.

[0405] In addition to this, the inorganic insulating film 125f can also be formed by a sputtering method, a CVD method, or a PECVD method with a deposition rate higher than that of the ALD method. Thereby, a display device with high reliability can be manufactured with high productivity.

[0406] The insulating film 127f is preferably formed by the above wet deposition method. The insulating film 127f is preferably formed by a spin coating method using a photosensitive material, and more specifically, it is preferably formed using a photosensitive resin composition containing an acrylic resin.

[0407] For example, it is preferable to form the insulating film 127f using a resin composition containing a polymer, an acid generator, and a solvent. The polymer is formed using one or more monomers and has a structure in which one or more structural units (also referred to as constituent units) are repeated regularly or irregularly. As the acid generator, one or both of a compound that generates an acid by irradiating light and a compound that generates an acid by heating can be used. The resin composition may further contain one or more of a photosensitizer, a sensitizer, a catalyst, an adhesion aid, a surfactant, and an antioxidant.

[0408] In addition, it is preferable to perform a heat treatment (also referred to as pre-baking) after forming the insulating film 127f. This heat treatment is performed at a temperature lower than the heat-resistant temperature of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B. The substrate temperature during the heat treatment is preferably 50°C or higher and 200°C or lower, more preferably 60°C or higher and 150°C or lower, and further preferably 70°C or higher and 120°C or lower. Thereby, the solvent in the insulating film 127f can be removed.

[0409] Next, exposure is performed to expose a part of the insulating film 127f with visible light or ultraviolet light. Here, when a positive photosensitive resin composition containing an acrylic resin is used for the insulating film 127f, visible light or ultraviolet light is irradiated onto the region where the insulating layer 127 will not be formed in the subsequent process. The insulating layer 127 is formed in the region sandwiched by any two of the conductive layers 152R, the conductive layer 152G, and the conductive layer 152B and around the conductive layer 152C. Therefore, visible light or ultraviolet light is irradiated onto the conductive layers 152R, the conductive layer 152G, the conductive layer 152B, and the conductive layer 152C. Note that when a negative photosensitive material is used for the insulating film 127f, visible light or ultraviolet light is irradiated onto the region where the insulating layer 127 will be formed.

[0410] By means of the exposed region of the insulating film 127f, the width of the insulating layer 127 to be formed later can be controlled. In the present embodiment, processing is performed such that the insulating layer 127 has a portion overlapping with the top surface of the conductive layer 151.

[0411] The light used for exposure preferably has i-line (wavelength 365 nm). In addition, the light used for exposure may also have at least one of g-line (wavelength 436 nm) and h-line (wavelength 405 nm).

[0412] Here, by providing an oxygen barrier insulating layer (such as an alumina film, etc.) as one or both of the sacrificial layer 158 (sacrificial layer 158R, sacrificial layer 158G, and sacrificial layer 158B) and the inorganic insulating film 125f, oxygen diffusion into the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be suppressed. When light (visible light or ultraviolet light) is irradiated onto the organic compound layer, sometimes the organic compound contained in the organic compound layer becomes excited and promotes the reaction with oxygen in the atmosphere. Specifically, when light (visible light or ultraviolet light) is irradiated onto the organic compound layer in an oxygen-containing atmosphere, oxygen may bond to the organic compound contained in the organic compound layer. By providing the sacrificial layer 158 and the inorganic insulating film 125f on the island-shaped organic compound layer, oxygen in the atmosphere can be suppressed from bonding to the organic compound contained in the organic compound layer.

[0413] Next, as Figure 11AAs shown, the exposed area in the insulating film 127f is removed by development to form the insulating layer 127a. The insulating layer 127a is formed in the area sandwiched by any two of the conductive layer 152R, the conductive layer 152G, and the conductive layer 152B and the area surrounding the conductive layer 152C. Here, in the case of using an acrylic resin for the insulating film 127f, an alkaline solution, such as TMAH, can be used as a developer.

[0414] Next, residues left during development (so-called scum) may be removed. For example, the residues may be removed by ashing using oxygen plasma.

[0415] In addition, etching may be performed to adjust the height of the surface of the insulating layer 127a. The insulating layer 127a may be processed by, for example, ashing using oxygen plasma. In addition, when a non-photosensitive material is used as the insulating film 127f, the height of the surface of the insulating film 127f may also be adjusted by, for example, ashing.

[0416] Then, if Figure 11B As shown, the insulating layer 127a is used as a mask to perform etching to remove a portion of the inorganic insulating film 125f, thereby reducing the thickness of a portion of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B. As a result, the inorganic insulating layer 125 is formed under the insulating layer 127a. In addition, the surface of the portion of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B with a smaller thickness is exposed. Hereinafter, the etching process using the insulating layer 127a as a mask is sometimes referred to as the first etching process.

[0417] The first etching process can be performed by dry etching or wet etching. When the inorganic insulating film 125f is deposited using the same material as the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, the first etching process can be performed at once, which is preferable.

[0418] By using the insulating layer 127 a having tapered side surfaces as a mask for etching, the side surfaces of the inorganic insulating layer 125 and the upper end portions of the side surfaces of the sacrificial layers 158R, 158G, and 158B can be easily tapered.

[0419] When dry etching is performed, chlorine-based gas is preferably used. As the chlorine-based gas, one gas selected from Cl2, BCl3, SiCl4, and CCl4, or a mixture of two or more of the above gases, can be used. In addition, one gas selected from oxygen gas, hydrogen gas, helium gas, and argon gas, or a mixture of two or more of the above gases, can be appropriately added to the above chlorine-based gas. By utilizing dry etching, regions where the thickness of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B is small can be formed with excellent in-plane uniformity.

[0420] As a dry etching device, a dry etching device having a high-density plasma source can be used. For example, as a dry etching device having a high-density plasma source, for example, an inductively coupled plasma (ICP: Inductively Coupled Plasma) etching device can be used. Alternatively, a capacitively coupled plasma (CCP: Capacitively Coupled Plasma) etching device including parallel plate electrodes can be used. The capacitively coupled plasma etching device including parallel plate electrodes can also adopt a structure in which a high-frequency voltage is applied to one of the parallel plate electrodes. Alternatively, a structure in which multiple different high-frequency voltages are applied to one of the parallel plate electrodes can also be adopted. Alternatively, a structure in which a high-frequency voltage with the same frequency is applied to each of the parallel plate electrodes can also be adopted. Alternatively, a structure in which high-frequency voltages with different frequencies are applied to each of the parallel plate electrodes can also be adopted.

[0421] In addition, when dry etching is performed, byproducts generated during dry etching may be deposited on the top surface and side surfaces of the insulating layer 127a. As a result, components in the etching gas, components in the inorganic insulating film 125f, components in the sacrificial layers 158R, 158G, and 158B may be included in the insulating layer 127 after the display device is completed.

[0422] In addition, it is preferred to perform the first etching process using wet etching. By using the wet etching method, the damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be further reduced compared to the case of using the dry etching method. For example, wet etching can be performed using an alkaline solution. For example, TMAH, an alkaline solution, can be used in the wet etching of the aluminum oxide film. At this time, wet etching can be performed in a glue coating manner. When the inorganic insulating film 125f is deposited using the same material as the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, the above-mentioned etching process can be performed at one time, so it is preferred.

[0423] In the first etching process, the sacrificial layers 158R, 158G, and 158B are not completely removed, and the etching process is stopped in a state where the thickness is reduced. In this way, by leaving the corresponding sacrificial layers 158R, 158G, and 158B on the organic compound layers 103R, 103G, and 103B, the organic compound layers 103R, 103G, and 103B can be prevented from being damaged in the subsequent process.

[0424] Next, the entire substrate is preferably exposed to visible light or ultraviolet light to irradiate the insulating layer 127a. The energy density of this exposure is preferably higher than 0 mJ / cm 2and 800 mJ / cm 2 Hereinafter, it is more preferably higher than 0 mJ / cm 2 and 500 mJ / cm 2 Hereinafter. By performing such exposure after development, the transparency of the insulating layer 127a can sometimes be improved. In addition, the substrate temperature required for the heat treatment for deforming the insulating layer 127a into a tapered shape in the subsequent process can sometimes be reduced.

[0425] Here, by providing an oxygen barrier insulating layer (such as an alumina film or the like) as the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, oxygen diffusion into the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be suppressed. When light (visible light or ultraviolet light) is irradiated onto the organic compound layer, sometimes the organic compounds contained in the organic compound layer become excited states and promote reactions with oxygen in the atmosphere. Specifically, when light (visible light or ultraviolet light) is irradiated onto the organic compound layer in an oxygen-containing atmosphere, oxygen may bond to the organic compounds contained in the organic compound layer. By providing the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B on the island-shaped organic compound layer, oxygen in the atmosphere can be suppressed from bonding to the organic compounds contained in the organic compound layer.

[0426] Next, a heat treatment (also referred to as post-baking) is performed. By performing the heat treatment, the insulating layer 127a can be deformed into an insulating layer 127 having a tapered shape on its side surface ( Figure 11C ). This heat treatment is performed at a temperature lower than the heat-resistant temperature of the organic compound layer. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 130°C or lower. The heating atmosphere can be either an air atmosphere or an inert gas. In addition, the heating atmosphere can be either an air atmosphere or a reduced-pressure atmosphere. In the heat treatment of this step, it is preferable to increase the substrate temperature compared to the heat treatment (pre-baking) after forming the insulating film 127f. Thereby, the adhesion between the insulating layer 127 and the inorganic insulating layer 125 can be improved, and the corrosion resistance of the insulating layer 127 can also be improved.

[0427] In the first etching treatment, by not completely removing the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B and leaving the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B in a state where the thickness is thinned, damage and deterioration of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be prevented during this heat treatment. Thereby, the reliability of the light-emitting device can be improved.

[0428] Note that depending on the material of the insulating layer 127, and the temperature, time, and atmosphere of the post-baking, sometimes a concave curved surface shape is formed on the side surface of the insulating layer 127. For example, the higher the temperature or the longer the time in the post-baking conditions, the more likely the shape of the insulating layer 127 is to change, and thus sometimes a concave curved surface shape is formed.

[0429] Next, as Figure 12A shown, the insulating layer 127 is used as a mask for an etching process to remove a part of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B. Note that sometimes a part of the inorganic insulating layer 125 is also removed. As a result, openings are respectively formed in the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, and the top surfaces of the organic compound layer 103R, the organic compound layer 103G, the organic compound layer 103B, and the conductive layer 152C are exposed. Hereinafter, the etching process using the insulating layer 127 as a mask is sometimes referred to as the second etching process.

[0430] The end portion of the inorganic insulating layer 125 is covered by the insulating layer 127. In addition, Figure 12A an example is shown in which a part of the end portion of the sacrificial layer 158G (specifically, the conical-shaped part formed by the first etching process) is covered by the insulating layer 127 and the conical-shaped part formed by the second etching process is exposed.

[0431] When the first etching process is not performed and the etching process of the inorganic insulating layer 125 and the mask layer is performed at once after the post-baking, sometimes the inorganic insulating layer 125 and the mask layer under the end portion of the insulating layer 127 disappear due to side etching to form a cavity. Due to this cavity, irregularities are generated on the surface on which the common electrode 155 is formed, and disconnection is likely to occur in the common electrode 155. Even if the inorganic insulating layer 125 and the mask layer are side-etched to form a cavity after the first etching process, the cavity can be filled by the insulating layer 127 through the subsequent post-baking. Then, in the second etching process, the mask layer with a further reduced thickness is etched, so the amount of side etching is small, it is not easy to form a cavity, and the cavity that can be formed can also be extremely small. Therefore, the surface on which the common electrode 155 is formed can be made flatter.

[0432] The insulating layer 127 may also cover the entire end portion of the sacrificial layer 158G. For example, the end portion of the insulating layer 127 sometimes droops to cover the end portion of the sacrificial layer 158G. In addition, for example, the end portion of the insulating layer 127 sometimes contacts the top surface of at least one of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B. As described above, when the insulating layer 127a after development is not exposed, the shape of the insulating layer 127 is sometimes liable to change.

[0433] The second etching process is performed using wet etching. By using the wet etching method, damage to the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B can be further reduced compared to the case of using the dry etching method. The wet etching can be performed using an alkaline solution such as TMAH.

[0434] On the other hand, when the second etching process is performed using the wet etching method, if there are gaps at the interfaces between the organic compound layer 103 and the sacrificial layer 158, between the organic compound layer 103 and the inorganic insulating layer 125, and between the organic compound layer 103 and the insulating layer 175 due to problems such as the adhesion between the organic compound layer 103 and other layers, the chemical solution used in the second etching process sometimes enters these gaps and contacts the pixel electrode. Here, when the chemical solution contacts both the conductive layer 151 and the conductive layer 152, sometimes the conductive layer with the lower natural potential of the conductive layer 151 and the conductive layer 152 corrodes due to galvanic corrosion. For example, when aluminum is used as the conductive layer 151 and indium tin oxide is used as the conductive layer 152, sometimes the conductive layer 152 corrodes. As a result, the yield of the display device sometimes decreases. In addition, the reliability of the display device sometimes decreases.

[0435] As described above, by forming the insulating layer 156 so as to have a region overlapping with the side surface of the conductive layer 151 and forming the insulating layer 156 so as to cover the conductive layer 151 and the conductive layer 152, disconnection of the inorganic insulating layer 125 can be prevented. Therefore, for example, it is possible to prevent the chemical solution from contacting the underlying structure such as the conductive layer 151 during the second etching process. Thereby, corrosion of the pixel electrode can be prevented.

[0436] As described above, by providing the insulating layer 127, the inorganic insulating layer 125, the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, between each light-emitting device, it is possible to suppress poor connection due to disconnection in the common electrode 155 and an increase in resistance due to a portion with a locally thin thickness. Thereby, the display device according to one embodiment of the present invention can improve the display quality.

[0437] In addition, a heat treatment may also be performed after a part of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B is exposed. By this heat treatment, water contained in each organic compound layer and water adsorbed on the surface of each organic compound layer can be removed. In addition, the shape of the insulating layer 127 sometimes changes due to this heat treatment. Specifically, the insulating layer 127 sometimes expands so as to cover at least one of the end portion of the inorganic insulating layer 125, the end portions of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, and the top surface of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B.

[0438] When the temperature of the heat treatment is too low, water contained in each organic compound layer and water adsorbed on the surface of each organic compound layer cannot be removed. In addition, when the temperature of the heat treatment is too high, deterioration of the organic compound layer 103 and excessive change in the shape of the insulating layer 127 may occur. Therefore, the heat treatment temperature is preferably higher than the temperature at which water dissociates from the organic compound layer 103 and lower than the glass transition temperature of the organic compound contained in the organic compound layer 103, and more preferably lower than the glass transition temperature of the organic compound contained in the top surface of the organic compound layer 103. Specifically, the substrate temperature is preferably 80°C or higher and 130°C or lower, more preferably 90°C or higher and 120°C or lower, further preferably 100°C or higher and 120°C or lower, and still further preferably 100°C or higher and 110°C or lower. The heating atmosphere can be either an air atmosphere or an inert gas. Note that the heating atmosphere can be an atmospheric pressure atmosphere or a reduced pressure atmosphere, and a reduced pressure atmosphere is preferably used to prevent re-adsorption of the water dissociated from the organic compound layer 103.

[0439] Through this heat treatment, water contained in each organic compound layer, water adsorbed on the surface of each organic compound layer, etc. can be sufficiently removed without deterioration of the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B and excessive change in the shape of the insulating layer 127. Thereby, deterioration of the characteristics of the light-emitting device can be prevented.

[0440] Next, as Figure 12B shown, a common layer 104 and a common electrode 155 are formed on the organic compound layer 103R, the organic compound layer 103G, the organic compound layer 103B, the conductive layer 152C, and the insulating layer 127. The common layer 104 and the common electrode 155 can be formed by a method such as sputtering or vacuum evaporation. Alternatively, the common layer 104 can be formed by evaporation and the common electrode 155 can be formed by sputtering.

[0441] Next, as Figure 12C shown, a protective layer 135 is formed on the common electrode 155. The protective layer 135 can be formed by a method such as vacuum evaporation, sputtering, CVD, or ALD.

[0442] Next, a display device can be manufactured by bonding the substrate 120 to the protective layer 135 using the resin layer 122. As described above, in the method for manufacturing a display device according to one embodiment of the present invention, the insulating layer 156 is provided on the sides of the conductive layer 151 and the conductive layer 152. Thereby, the yield of the display device can be improved and the occurrence of defects can be suppressed.

[0443] As described above, in the method for manufacturing a display device according to one embodiment of the present invention, the island-shaped organic compound layer 103R, the island-shaped organic compound layer 103G, and the island-shaped organic compound layer 103B are not formed using a high-precision metal mask but are formed by depositing a film on one surface and then processing it. Therefore, the island-shaped layers can be formed with a uniform thickness. Moreover, a high-definition display device or a display device with a high aperture ratio can be realized. In addition, even when the definition or aperture ratio is high and the distance between sub-pixels is extremely short, it is possible to suppress the contact between the organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B in adjacent sub-pixels. Therefore, it is possible to suppress the generation of leakage current between sub-pixels. As a result, crosstalk can be prevented to realize a display device with extremely high contrast. Additionally, a display device can be provided that has good characteristics even when including a tandem light-emitting device manufactured by lithography technology.

[0444] The structure of this embodiment can be used in appropriate combination with the structures of other embodiments.

[0445] Embodiment 4 In this embodiment, with reference to Figures 13A to 13G and Figures 14A to 14I a light-emitting device according to one embodiment of the present invention will be described.

[0446] [Layout of pixels] In this embodiment, a pixel layout different from Figure 5A will be mainly described. There is no particular limitation on the arrangement of sub-pixels, and various arrangement methods can be adopted. As the arrangement of sub-pixels, for example, stripe arrangement, S-stripe arrangement, matrix arrangement, Delta arrangement, Bayer arrangement, and Pentile arrangement can be cited.

[0447] In this embodiment, the top surface shape of the sub-pixels shown in the drawings corresponds to the top surface shape of the light-emitting region.

[0448] In addition, as the top surface shape of the sub-pixels, for example, polygons such as triangles, quadrangles (including rectangles and squares), pentagons, etc., the above-mentioned polygon shapes with rounded corners, ellipses, or circles can be cited.

[0449] In addition, the circuit layout constituting the sub-pixels is not limited to the range of the sub-pixels shown in the drawings and can also be arranged outside thereof.

[0450] Figure 13A The pixel 178 shown adopts an S-stripe arrangement. Figure 13A The pixel 178 shown is composed of three sub-pixels: a sub-pixel 110R, a sub-pixel...

Claims

1. A light emitting device, comprising: A light-emitting layer between a pair of electrodes, The light-emitting layer includes a first compound, a material configured to convert triplet excitation energy into light-emitting material, and a material configured to convert singlet excitation energy into light-emitting material. At least one of the first compound and the material configured to convert triplet excitation energy into luminescence contains deuterium, Furthermore, light emission is obtained from the material configured to convert singlet excitation energy into light emission.

2. A light emitting device, comprising: A light-emitting layer between a pair of electrodes, The light-emitting layer includes a first compound, a second compound, a material configured to convert triplet excitation energy into light emission, and a material configured to convert singlet excitation energy into light emission. At least one of the first compound, the second compound, and the material configured to convert triplet excitation energy into luminescence contains deuterium, Furthermore, light emission is obtained from the material configured to convert singlet excitation energy into light emission.

3. The light emitting device according to claim 2, wherein the first compound comprises a π-electron-deficient heteroaromatic ring, And the second compound includes at least one of a π-electron-rich heteroaromatic ring and an aromatic amine skeleton.

4. The light emitting device according to claim 2, The difference between the lowest triplet excitation energy level of the first compound and the lowest triplet excitation energy level of the second compound is less than 0.20 eV.

5. The light emitting device according to claim 2, wherein the first compound and the second compound are a combination that forms an exciplex, And the emission spectrum of the exciplex overlaps with the emission spectrum of the material configured to convert triplet excitation energy into luminescence.

6. The light emitting device according to claim 1, wherein the first compound comprises deuterium, Furthermore, the phosphorescence lifetime or delayed fluorescence lifetime of the first compound at 77K is longer than the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of the first compound at 77K.

7. The light emitting device according to claim 2, wherein the second compound comprises deuterium, Furthermore, the phosphorescence lifetime or delayed fluorescence lifetime of the second compound at 77K is longer than the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of the second compound at 77K.

8. The light emitting device according to claim 1, wherein the material that converts triplet excitation energy into luminescence contains deuterium, Furthermore, the phosphorescence lifetime or delayed fluorescence lifetime of the material that converts triplet excitation energy into luminescence at room temperature is longer than the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of the material that converts triplet excitation energy into luminescence at room temperature.

9. The light emitting device according to claim 1, The material configured to convert triplet excitation energy into luminescence is a phosphorescent substance.

10. The light emitting device according to claim 1, The material configured to convert triplet excitation energy into luminescence is a TADF material.

11. The light emitting device according to claim 1, The material configured to convert singlet excitation energy into luminescence is a fluorescent substance.

12. The light emitting device according to claim 1, wherein the material configured to convert singlet excitation energy into luminescence is a fluorescent substance including a luminophore and a protective group, The luminophore is a fused aromatic ring or a fused heteroaromatic ring, The protecting group includes any one of an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms.

13. The light emitting device according to claim 12, wherein the protecting group further comprises deuterium.

14. The light emitting device according to claim 1, The material configured to convert singlet excitation energy into luminescence is a TADF material.

15. The light emitting device according to claim 2, wherein the first compound comprises deuterium, Furthermore, the phosphorescence lifetime or delayed fluorescence lifetime of the first compound at 77K is longer than the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of the first compound at 77K.

16. The light emitting device according to claim 2, wherein the material that converts triplet excitation energy into luminescence contains deuterium, Furthermore, the phosphorescence lifetime or delayed fluorescence lifetime of the material that converts triplet excitation energy into luminescence at room temperature is longer than the phosphorescence lifetime or delayed fluorescence lifetime of the non-deuterated form of the material that converts triplet excitation energy into luminescence at room temperature.

17. The light emitting device according to claim 2, The material configured to convert triplet excitation energy into luminescence is a phosphorescent substance.

18. The light emitting device according to claim 2, The material configured to convert singlet excitation energy into luminescence is a fluorescent substance.

19. The light emitting device according to claim 2, wherein the material configured to convert singlet excitation energy into luminescence is a fluorescent substance including a luminophore and a protective group, The luminophore is a fused aromatic ring or a fused heteroaromatic ring, The protecting group includes any one of an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms.

20. The light emitting device according to claim 19, wherein the protecting group further comprises deuterium.

21. The light emitting device according to claim 2, The material configured to convert singlet excitation energy into luminescence is a TADF material.

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