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

Abstract

A novel light-emitting device is provided. Or a light-emitting device with high light-emitting efficiency is provided. Or a light-emitting device with a long lifespan is provided. Or a light-emitting device with a low driving voltage is provided. A light-emitting device is provided comprising an EL layer including a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer comprises a first organic compound and a second organic compound. The fourth layer comprises a seventh organic compound. The first organic compound exhibits electron acceptability with respect to the second organic compound. The HOMO level of the second organic compound is -5.7 eV to -5.4 eV. The HOMO level of the seventh organic compound is -6.0 eV or higher.

Description

Technology Field

[0001] One embodiment of the present invention relates to a light-emitting element, a light-emitting device, a display module, a lighting module, a display device, a light-emitting device, an electronic device, and a lighting device. Furthermore, one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification, etc. relates to an object, a method, or a method of manufacturing. One embodiment of the present invention relates to a process, a machine, a product, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a storage device, a memory device, an imaging device, a method of driving the same, and a method of manufacturing the same. Background Technology

[0002] Light-emitting devices (organic EL devices) containing organic compounds and utilizing electroluminescence (EL) are being commercialized. In the basic structure of such light-emitting devices, an organic compound layer (EL layer) containing a light-emitting material is interposed between a pair of electrodes. By applying voltage to this device to inject carriers and using the recombination energy of the carriers, light emission can be obtained from the light-emitting material.

[0003] Since these light-emitting devices are self-emissive, when used as pixels in a display, they offer the advantage of higher pixel visibility compared to liquid crystals and eliminate the need for a backlight. Displays containing these light-emitting devices are also highly advantageous in that they can be made thin and light. In addition, these light-emitting devices have the characteristic of having a very fast response speed.

[0004] Since the light-emitting layer of such a light-emitting device can be formed continuously in two dimensions, surface light emission can be realized. This feature is difficult to realize with point light sources, such as incandescent lamps and LEDs, or line light sources, such as fluorescent lamps. Therefore, the light-emitting device has high utility value as a surface light source that can be applied to lighting devices, etc.

[0005] As mentioned above, display or lighting devices including light-emitting devices can be suitablely used in various electronic devices, but research and development of light-emitting devices is underway to achieve higher efficiency or a longer lifespan.

[0006] In the structure disclosed in Patent Document 1, a hole transportable material is provided between the light-emitting layer and the first hole transport layer in contact with the hole injection layer, wherein the HOMO level is between the HOMO level of the first hole injection layer and the HOMO level of the host material.

[0007] Although the characteristics of light-emitting devices have improved significantly, they have not yet met the high demands for various characteristics, including efficiency and durability. Prior art literature

[0008] Pamphlet for International Publication WO2011 / 065136 The problem to be solved

[0009] One objective of the present invention is to provide a novel light-emitting device. Another objective of one embodiment of the present invention is to provide a light-emitting device with high luminous efficiency. Another objective of one embodiment of the present invention is to provide a light-emitting device with a long lifespan. Another objective of one embodiment of the present invention is to provide a light-emitting device with a low driving voltage.

[0010] Another objective of one embodiment of the present invention is to provide a highly reliable light-emitting device, an electronic device, and a display device, each. Another objective of one embodiment of the present invention is to provide a light-emitting device, an electronic device, and a display device, each having low power consumption.

[0011] In the present invention, it is sufficient to achieve at least one of the above-described problems. means of solving the problem

[0012] One embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a light-emitting layer. A degradation curve representing a change in luminance of light obtained when a constant current is supplied to the light-emitting device has a maximum value.

[0013] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound. The first organic compound exhibits electron acceptivity with respect to the second organic compound. The fifth organic compound is a light-emitting central material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The electron mobility of the seventh organic compound when the square root of the electric field strength [V / cm] is 600 is 1 × 10⁻¹⁰. -7 cm 2 / Vs 5X10 or more -5 cm 2 It is less than or equal to / Vs. The degradation curve representing the change in luminance of the light emitted when a constant current is supplied to the above-mentioned light-emitting device has a maximum value.

[0014] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound. The first organic compound exhibits electron acceptivity with respect to the second organic compound. The fifth organic compound is a light-emitting center material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The electron mobility of the seventh organic compound when the square root of the electric field strength [V / cm] is 1×10⁻⁶ -7 cm 2 / Vs 5X10 or more -5 cm 2 / Vs or less. The HOMO level of the seventh organic compound is -6.0 eV or higher. The degradation curve representing the change in luminance of the luminescence obtained when a constant current is supplied to the above-mentioned light-emitting device has a maximum value.

[0015] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound. The first organic compound exhibits electron acceptivity with respect to the second organic compound. The fifth organic compound is a light-emitting central material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The difference between the HOMO level of the third organic compound and the HOMO level of the second organic compound is 0.2 eV or less. The HOMO level of the third organic compound is equal to or deeper than the HOMO level of the second organic compound. The electron mobility of the seventh organic compound when the square root of the electric field strength [V / cm] is 1×10⁻⁶ -7 cm 2 / Vs 5X10 or more -5 cm 2 / Vs or less. The HOMO level of the seventh organic compound is -6.0 eV or higher. The degradation curve representing the change in luminance of the luminescence obtained when a constant current is supplied to the above-mentioned light-emitting device has a maximum value.

[0016] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound. The first organic compound exhibits electron acceptability with respect to the second organic compound. The second organic compound comprises a first hole-transporting framework. The third organic compound comprises a second hole-transporting framework. The fourth organic compound comprises a third hole-transporting framework. The fifth organic compound is a light-emitting center material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The first, second, and third hole transport backbones are each independently one of the carbazole backbone, dibenzofuran backbone, dibenzothiophen backbone, and anthracene backbone. The electron mobility of the seventh organic compound when the square root of the electric field strength [V / cm] is 1×10⁻¹⁰ -7 cm 2 / Vs 5X10 or more -5 cm 2 / Vs or less. The HOMO level of the seventh organic compound is -6.0 eV or higher. The degradation curve representing the change in luminance of the luminescence obtained when a constant current is supplied to the above-mentioned light-emitting device has a maximum value.

[0017] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound and an eighth material. The first organic compound exhibits electron acceptability with respect to the second organic compound. The fifth organic compound is a light-emitting central material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The seventh organic compound is an organic compound comprising an anthracene backbone. The eighth material is an organic complex of an alkali metal or an alkaline earth metal. The degradation curve representing the change in luminance of the light emitted when a constant current is supplied to the light-emitting device has a maximum value.

[0018] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound and an eighth material. The first organic compound exhibits electron acceptability with respect to the second organic compound. The fifth organic compound is a light-emitting central material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The difference between the HOMO level of the third organic compound and the HOMO level of the second organic compound is 0.2 eV or less. The HOMO level of the third organic compound is equal to or deeper than the HOMO level of the second organic compound. The seventh organic compound is an organic compound containing an anthracene skeleton. The eighth substance is an organic complex of an alkali metal or alkaline earth metal. The degradation curve representing the change in luminance of the luminescence obtained when a constant current is supplied to the light-emitting device has a maximum value.

[0019] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound and an eighth material. The first organic compound exhibits electron acceptability with respect to the second organic compound. The second organic compound comprises a first hole-transporting framework. The third organic compound comprises a second hole-transporting framework. The fourth organic compound comprises a third hole-transporting framework. The fifth organic compound is a light-emitting center material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The first hole transport framework, the second hole transport framework, and the third hole transport framework are each independently one of the carbazole framework, the dibenzofuran framework, the dibenzothiophene framework, and the anthracene framework. The seventh organic compound is an organic compound containing the anthracene framework. The eighth substance is an organic complex of an alkali metal or an alkaline earth metal. The degradation curve representing the change in luminance of the luminescence obtained when a constant current is supplied to the light-emitting device has a maximum value.

[0020] Another embodiment of the present invention is a light-emitting device having the above structure, having a portion of the degradation curve with a luminance exceeding 100%.

[0021] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound. The first organic compound exhibits electron acceptivity with respect to the second organic compound. The fifth organic compound is a light-emitting center material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The electron mobility of the seventh organic compound when the square root of the electric field strength [V / cm] is 1×10⁻⁶ -7 cm 2 / Vs 5X10 or more -5 cm 2 / Vs is less than or equal to. The HOMO level of the 7th organic compound is greater than or equal to -6.0 eV.

[0022] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound. The first organic compound exhibits electron acceptivity with respect to the second organic compound. The fifth organic compound is a light-emitting central material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The difference between the HOMO level of the third organic compound and the HOMO level of the second organic compound is 0.2 eV or less. The HOMO level of the third organic compound is equal to or deeper than the HOMO level of the second organic compound. The electron mobility of the seventh organic compound when the square root of the electric field strength [V / cm] is 1×10⁻⁶ -7 cm 2 / Vs 5X10 or more -5 cm 2 / Vs is less than or equal to. The HOMO level of the 7th organic compound is greater than or equal to -6.0 eV.

[0023] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound. The first organic compound exhibits electron acceptability with respect to the second organic compound. The second organic compound comprises a first hole-transporting framework. The third organic compound comprises a second hole-transporting framework. The fourth organic compound comprises a third hole-transporting framework. The fifth organic compound is a light-emitting center material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The first, second, and third hole transport backbones are each independently one of the carbazole backbone, dibenzofuran backbone, dibenzothiophen backbone, and anthracene backbone. The electron mobility of the seventh organic compound when the square root of the electric field strength [V / cm] is 1×10⁻¹⁰ -7 cm 2 / Vs 5X10 or more -5 cm 2 / Vs is less than or equal to. The HOMO level of the 7th organic compound is greater than or equal to -6.0 eV.

[0024] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound and an eighth material. The first organic compound exhibits electron acceptability with respect to the second organic compound. The fifth organic compound is a light-emitting central material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The seventh organic compound is an organic compound comprising an anthracene backbone. The eighth substance is an organic complex of an alkali metal or alkaline earth metal.

[0025] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound and an eighth material. The first organic compound exhibits electron acceptability with respect to the second organic compound. The fifth organic compound is a light-emitting central material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The difference between the HOMO level of the third organic compound and the HOMO level of the second organic compound is 0.2 eV or less. The HOMO level of the third organic compound is equal to or deeper than the HOMO level of the second organic compound. The seventh organic compound is an organic compound containing an anthracene skeleton. The eighth substance is an organic complex of an alkali metal or alkaline earth metal.

[0026] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer between the anode and the cathode. The EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side. The first layer is in contact with the anode. The fourth layer is in contact with the light-emitting layer. The first layer comprises a first organic compound and a second organic compound. The second layer comprises a third organic compound. The third layer comprises a fourth organic compound. The light-emitting layer comprises a fifth organic compound and a sixth organic compound. The fourth layer comprises a seventh organic compound and an eighth material. The first organic compound exhibits electron acceptability with respect to the second organic compound. The second organic compound comprises a first hole-transporting framework. The third organic compound comprises a second hole-transporting framework. The fourth organic compound comprises a third hole-transporting framework. The fifth organic compound is a light-emitting center material. The HOMO level of the second organic compound is between -5.7 eV and -5.4 eV. The first hole-transporting backbone, the second hole-transporting backbone, and the third hole-transporting backbone are each independently any one of the carbazole backbone, the dibenzofuran backbone, the dibenzothiophen backbone, and the anthracene backbone. The seventh organic compound is an organic compound containing the anthracene backbone. The eighth substance is an organic complex of an alkali metal or alkaline earth metal.

[0027] Another embodiment of the present invention is a light-emitting device having the structure in which the seventh organic compound comprises an anthracene backbone and a heterocyclic backbone.

[0028] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the electron mobility of the seventh organic compound is lower than the electron mobility of the sixth organic compound.

[0029] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the difference in HOMO levels between the third organic compound and the fourth organic compound is 0.2 eV or less.

[0030] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the HOMO level of the fourth organic compound is deeper than the HOMO level of the third organic compound.

[0031] Another embodiment of the present invention is a light-emitting device having the structure, wherein the second organic compound comprises a dibenzofuran backbone.

[0032] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the second organic compound and the third organic compound are the same material.

[0033] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the fifth organic compound is a blue fluorescent material.

[0034] Another embodiment of the present invention is an electronic device comprising a sensor, an operating button, a speaker, or a microphone in the above structure.

[0035] Another embodiment of the present invention is a light-emitting device comprising a transistor or a substrate in the above structure.

[0036] Another embodiment of the present invention is a lighting device comprising a housing in the above structure.

[0037] In addition, the light-emitting device in this specification includes image display devices using the light-emitting device within its category. The light-emitting device may be included in a module in which a connector such as an anisotropic conductive film or a TCP (tape carrier package) is provided on the light-emitting device, a module in which a printed circuit board is provided at the end of the TCP, and a module in which an integrated circuit (IC) is directly mounted on the light-emitting device by a COG (chip on glass) method. The light-emitting device may be included in a lighting device, etc. Effects of the invention

[0038] One embodiment of the present invention may provide a novel light-emitting device. Another embodiment of the present invention may provide a light-emitting device with a long lifespan. Another embodiment of the present invention may provide a light-emitting device with high luminous efficiency.

[0039] Another embodiment of the present invention may provide a highly reliable light-emitting device, an electronic device, and a display device, each. Another embodiment of the present invention may provide a light-emitting device, an electronic device, and a display device, each having low power consumption.

[0040] Furthermore, the description of these effects does not preclude the existence of other effects. One embodiment of the present invention is not necessarily required to achieve all of the effects described above. Other effects may become apparent and derivable from the description in the specification, drawings, and claims, etc. Brief explanation of the drawing

[0041] Regarding the attached drawings: Figures 1 (A) to (C) are schematic diagrams of a light-emitting device. Figures 2 (A) and (B) are drawings illustrating longevity. Figures 3 (A) and (B) are diagrams illustrating the increase in luminance. Figures 4 (A) and (B) are conceptual diagrams of an active matrix light-emitting device. Figures 5 (A) and (B) are conceptual diagrams of an active matrix light-emitting device. Figure 6 is a conceptual diagram of an active matrix light-emitting device. Figures 7 (A) and (B) are conceptual diagrams of a passive matrix light-emitting device. Figures 8 (A) and (B) illustrate a lighting device. Figures 9 (A), (B1), (B2), and (C) illustrate electronic devices. Figures 10 (A) to (C) illustrate electronic devices. Figure 11 illustrates a lighting device. Figure 12 illustrates a lighting device. FIG. 13 illustrates a display device and lighting device for vehicle mounting. Figures 14 (A) and (B) illustrate electronic devices. Figures 15 (A) to (C) illustrate electronic devices. Figure 16 shows the luminance-current density characteristics of light-emitting device 1. Figure 17 shows the current efficiency-luminance characteristics of light-emitting device 1. Figure 18 shows the luminance-voltage characteristics of light-emitting device 1. Figure 19 shows the current-voltage characteristics of light-emitting device 1. Figure 20 shows the external quantum efficiency-luminance characteristics of light-emitting device 1. Figure 21 shows the emission spectrum of light-emitting device 1. Figure 22 shows the time dependence of the normalized luminance of light-emitting device 1. Figure 23 shows the luminance-current density characteristics of light-emitting device 2. Figure 24 shows the current efficiency-luminance characteristics of light-emitting device 2. Figure 25 shows the luminance-voltage characteristics of light-emitting device 2. Figure 26 shows the current-voltage characteristics of light-emitting device 2. Figure 27 shows the external quantum efficiency-luminance characteristics of the light-emitting device 2. Figure 28 shows the emission spectrum of the light-emitting device 2. Figure 29 shows the time dependence of the normalized luminance of light-emitting device 2. Figure 30 shows the luminance-current density characteristics of light-emitting device 3. Figure 31 shows the current efficiency-luminance characteristics of light-emitting device 3. Figure 32 shows the luminance-voltage characteristics of the light-emitting device 3. Figure 33 shows the current-voltage characteristics of the light-emitting device 3. Figure 34 shows the external quantum efficiency-luminance characteristics of the light-emitting device 3. Figure 35 shows the emission spectrum of the light-emitting device 3. Figure 36 shows the time dependence of the normalized luminance of light-emitting device 3. Figure 37 illustrates the structure of an electron-only device. Figure 38 shows the current density-voltage characteristics of an electron-only device. Figure 39 shows the frequency characteristics of the calculated capacitance C when the DC voltage is 7.0V and the ratio of ZADN to Liq is 1:1. Figure 40 shows the frequency characteristics of -△B when the DC voltage is 7.0V and the ratio of ZADN to Liq is 1:1. Figure 41 shows the dependence of the electron mobility of organic compounds on electric field strength. Figure 42 shows the luminance-current density characteristics of the light-emitting device 4. Figure 43 shows the current efficiency-luminance characteristics of the light-emitting device 4. Figure 44 shows the luminance-voltage characteristics of the light-emitting device 4. Figure 45 shows the current-voltage characteristics of the light-emitting device 4. Figure 46 shows the external quantum efficiency-luminance characteristics of the light-emitting device 4. Figure 47 shows the emission spectrum of the light-emitting device 4. Figure 48 shows the time dependence of the normalized luminance of light-emitting device 4. Figure 49 shows the luminance-current density characteristics of the light-emitting device 5. Figure 50 shows the current efficiency-luminance characteristics of the light-emitting device 5. Figure 51 shows the luminance-voltage characteristics of the light-emitting device 5. Figure 52 shows the current-voltage characteristics of the light-emitting device 5. Figure 53 shows the external quantum efficiency-luminance characteristics of the light-emitting device 5. Figure 54 shows the emission spectrum of the light-emitting device 5. Figure 55 shows the time dependence of the normalized luminance of light-emitting device 5. Figure 56 shows the luminance-current density characteristics of the light-emitting device 6. Figure 57 shows the current efficiency-luminance characteristics of the light-emitting device 6. Figure 58 shows the luminance-voltage characteristics of the light-emitting device 6. Figure 59 shows the current-voltage characteristics of the light-emitting device 6. Figure 60 shows the external quantum efficiency-luminance characteristics of the light-emitting device 6. Figure 61 shows the emission spectrum of the light-emitting device 6. Figure 62 shows the time dependence of the normalized luminance of the light-emitting device 6. Figure 63 shows the luminance-current density characteristics of the light-emitting device 7. Figure 64 shows the current efficiency-luminance characteristics of the light-emitting device 7. Figure 65 shows the luminance-voltage characteristics of the light-emitting device 7. Figure 66 shows the current-voltage characteristics of the light-emitting device 7. Figure 67 shows the external quantum efficiency-luminance characteristics of the light-emitting device 7. Figure 68 shows the emission spectrum of the light-emitting device 7. Figure 69 shows the time dependence of the normalized luminance of the light-emitting device 7. Figure 70 shows the luminance-current density characteristics of light-emitting device 8 and light-emitting device 9. Figure 71 shows the current efficiency-luminance characteristics of light-emitting device 8 and light-emitting device 9. Figure 72 shows the luminance-voltage characteristics of light-emitting device 8 and light-emitting device 9. Figure 73 shows the current-voltage characteristics of light-emitting device 8 and light-emitting device 9. Figure 74 shows the external quantum efficiency-luminance characteristics of light-emitting device 8 and light-emitting device 9. Figure 75 shows the emission spectra of light-emitting device 8 and light-emitting device 9. Figure 76 shows the time dependence of the normalized luminance of light-emitting device 8 and light-emitting device 9. Specific details for implementing the invention

[0042] Embodiments of the present invention will be described in detail below with reference to the drawings. Furthermore, the present invention is not limited to the description below, and it is readily understood by those skilled in the art that various modifications to the form and details of the present invention can be made without departing from the spirit and scope of the invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments below.

[0043] (Embodiment 1)

[0044] FIG. 1 (A) illustrates a light-emitting device according to one embodiment of the present invention. A light-emitting device according to one embodiment of the present invention includes an anode (101), a cathode (102), and an EL layer (103). The EL layer includes a hole injection layer (111), a hole transport layer (112), a light-emitting layer (113), and an electron transport layer (114).

[0045] Figure 1 (A) additionally illustrates an electron injection layer (115) on the EL layer (103), but the structure of the light-emitting device is not limited thereto. As long as it includes the components described above, layers having other functions may be included.

[0046] The hole injection layer (111) comprises a first organic compound and a second organic compound. The first organic compound exhibits electron acceptability with respect to the second organic compound. The second organic compound has a relatively deep HOMO level of -5.7 eV or higher and -5.4 eV or lower. The second organic compound having a relatively deep HOMO level facilitates the injection of holes into the hole transport layer (112).

[0047] As the first organic compound, for example, an organic compound having an electron-withdrawing group (especially a halogen group such as a cyano group or a fluoro group) can be used. Among these organic compounds, a substance that exhibits electron acceptance for the second organic compound is appropriately selected. Examples of such organic compounds include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated: F4-TCNQ), chloranyl, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated: F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene)malononitrile. Compounds in which an electron-withdrawing group is attached to a condensed aromatic ring having multiple heteroatoms, such as HAT-CN, are preferred because they are thermally stable. [3] Radialene derivatives having electron-withdrawing groups (especially halogen groups such as cyano groups or fluoro groups) are desirable because they have very high electron acceptability. Specific examples include α,α',α''-1,2,3-cyclopropanetriilydentris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriilydentris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriilydentris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0048] The second organic compound has hole transport properties and is preferably an organic compound having any one of a carbazole backbone, a dibenzofuran backbone, a dibenzothiophene backbone, and an anthracene backbone. In particular, it is preferable to use an aromatic amine having a substituent comprising a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine comprising a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine through an arylene group. Additionally, the second organic compound having an N,N-bis(4-biphenyl)amino group is preferred because it allows for the fabrication of a long-life light-emitting device. Specific examples of the second organic compound include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviated: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviated: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviated: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviated: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviated: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviated: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviated: BBAβNBi), 4-(2;1'-binaphthyl-6-yl)-4',4''-diphenyltriphenylamine (abbreviated: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binapthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-Diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4-(6;2'-binaphthyl-2-yl)-4',4''-diphenyltriphenylamine (abbreviation: BBA(βN2)B), 4-(2;2'-binaphthyl-7-yl)-4',4''-diphenyltriphenylamine (abbreviation: BBA(βN2)B-03), 4-(1;2'-binaphthyl-4-yl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNαNB), 4-(1;2'-binaphthyl-5-yl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-(1-naphthyl)-4'-phenyltriphenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazole-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazole-9-yl)phenyl]tris(1,1'-biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazole-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis([1,1'-biphenyl]-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis([1,1'-biphenyl]-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviated: BBASF(4)), N-(1,1'-biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluorene-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviated: oFBiSF),N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluorene-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluorene-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviated: PCBASF), and It includes N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9H-fluorene-2-amine (abbreviated: PCBBiF).

[0049] The hole transport layer (112) includes a first hole transport layer (112-1) and a second hole transport layer (112-2). The first hole transport layer (112-1) is closer to the anode (101) side than the second hole transport layer (112-2). Additionally, the second hole transport layer (112-2) may function as an electron blocking layer.

[0050] The first hole transport layer (112-1) and the second hole transport layer (112-2) each include a third organic compound and a fourth organic compound.

[0051] It is preferable that the third organic compound and the fourth organic compound are organic compounds having hole transport properties. As the third organic compound and the fourth organic compound, organic compounds that can be used as the second organic compound may likewise be used.

[0052] It is preferable that the materials of the second organic compound and the third organic compound be selected such that the HOMO level of the third organic compound is deeper than the HOMO level of the second organic compound and the difference between these HOMO levels is 0.2 eV or less. It is more preferable that the second organic compound and the third organic compound are the same material.

[0053] In addition, it is preferable that the HOMO level of the fourth organic compound is deeper than the HOMO level of the third organic compound. It is preferable that the materials of the third and fourth organic compounds be selected so that the difference in HOMO levels is 0.2 eV or less. If the HOMO levels of the second to fourth organic compounds are in the relationship described above, holes are smoothly injected into each layer, thereby preventing an increase in driving voltage and a shortage of holes in the light-emitting layer.

[0054] It is preferable that the second to fourth organic compounds each have a hole-transporting framework. It is preferable to use a carbazole framework, a dibenzofuran framework, a dibenzothiophene framework, and anthracene framework as hole-transporting frameworks, wherein the HOMO levels of the organic compounds do not become excessively shallow. It is preferable that materials of adjacent layers (e.g., the second organic compound and the third organic compound, or the third organic compound and the fourth organic compound) have the same hole-transporting framework, as this allows for smooth hole injection. In particular, it is preferable to use a dibenzofuran framework as a hole-transporting framework.

[0055] In addition, it is desirable that the materials included in adjacent layers (e.g., the second organic compound and the third organic compound, or the third organic compound and the fourth organic compound) be the same, as this allows for smooth injection of holes. In particular, it is desirable that the second organic compound and the third organic compound be the same material.

[0056] The light-emitting layer (113) includes a fifth organic compound and a sixth organic compound. The fifth organic compound is a light-emitting central material, and the sixth organic compound is a host material that disperses the fifth organic compound.

[0057] As the light-emitting central material, a fluorescent material, a phosphorescent material, a material exhibiting thermally activated delayed fluorescence (TADF), or other light-emitting materials may be used. Additionally, the light-emitting layer (113) may be a single layer or may comprise multiple layers including different light-emitting materials. Furthermore, one embodiment of the present invention is more suitable for use when the light-emitting layer (113) emits fluorescence, particularly blue fluorescence.

[0058] Examples of materials that can be used as fluorescent materials in the light-emitting layer (113) include 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviated: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviated: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluorene-9-yl)phenyl]pyrene-1,6-diamine (abbreviated: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene-9-yl)phenyl]pyrene-1,6-diamine (abbreviated: 1,6mMemFLPAPrn), N,N'-Bis[4-(9H-carbazole-9-yl)phenyl]-N,N'-Diphenylstilbene-4,4'-Diamine (abbreviation: YGA2S), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-Diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: PCAPA), Perylene, 2,5,8,11-Tetra(tert-butyl)Perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracen-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p] / / / Lysene-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-Diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazole-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-Diphenylquinacridone (abbreviation: DPQd), Rubrene, 5,12-Bis(1,1'-Biphenyl-4-yl)-6,11-Diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedynitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedynitrile (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)acenaphthor[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]quinolizine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedynitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedynitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedynitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-Benzo[ij]quinolizine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedynitrile (abbreviation: BisDCJTM), N,N'-(pyrene-1-,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazole-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02), 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated: 3,10FrA2Nbf(IV)-02) is included. Condensed aromatic diamine compounds, represented by pyrenediamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are particularly preferred because they have high hole trapping ability, high luminescence efficiency, and high reliability. Fluorescent materials other than these may also be used.

[0059] Examples of materials that can be used when a phosphorescent material is used as a luminescent center material in the light-emitting layer (113) include: an organometallic iridium complex having a 4H-triazole backbone such as tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazole-3-yl-κN2]phenyl-κC}iridium(III) (abbreviated: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazoleate)iridium(III) (abbreviated: [Ir(Mptz)3]), and tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazoleate]iridium(III) (abbreviated: [Ir(iPrptz-3b)3]). Organometallic iridium complexes having a 1H-triazole backbone, such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazoleto]iridium(III) (abbreviated: [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazoleto)iridium(III) (abbreviated: [Ir(Prptz1-Me)3]), fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviated: [Ir(iPrpmi)3]) and tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenantridinato]iridium(III) (abbreviated: Organometallic iridium complexes having an imidazole backbone such as [Ir(dmpimpt-Me)3]), and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]Iridium(III)tetrakis(1-pyrazolyl)borate (abbreviated: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]Iridium(III)picolinate (abbreviated: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinate-N,C 2'}Iridium(III)picolinate (abbreviated: [Ir(CF3ppy)2(pic)]), and bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2'There are organometallic iridium complexes in which phenylpyridine derivatives having electron-withdrawing groups, such as iridium(III) acetylacetonate (abbreviated: FIr(acac)), are coordinating ligands. These compounds emit blue phosphorescence and have emission peaks at 440 nm to 520 nm.

[0060] Other examples include tris(4-methyl-6-phenylpyrimidineto)iridium(III) (abbreviated: [Ir(mppm)3]), tris(4-tert-butyl-6-phenylpyrimidineto)iridium(III) (abbreviated: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidineto)iridium(III) (abbreviated: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidineto)iridium(III) (abbreviated: [Ir(tBuppm)2(acac)]), and (acetylacetonato)bis[6-(2-norvonyl)-4-phenylpyrimidineto]iridium(III) (abbreviated: Organometallic iridium complexes having a pyrimidine backbone such as [[Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidineto]iridium(III) (abbreviated: [Ir(mpmppm)2(acac)]), and (acetylacetonato)bis(4,6-diphenylpyrimidineto)iridium(III) (abbreviated: [Ir(dppm)2(acac)]), (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazineto)iridium(III) (abbreviated: [Ir(mppr-Me)2(acac)]), and Organometallic iridium complexes having a pyrazine backbone such as (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazineto)iridium(III) (abbreviated: [Ir(mppr-iPr)2(acac)]), tris(2-phenylpyridineto-N,C 2' )Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinate-N,C 2')iridium(III)acetylacetonate (abbreviation: [Ir(ppy)2acac]), bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2' )iridium(III) (abbreviated: [Ir(pq)3]), and bis(2-phenylquinolinato-N,C 2' Organometallic iridium complexes having a pyridine backbone, such as iridium(III) acetylacetonate (abbreviated: [Ir(pq)2(acac)]), and rare earth metal complexes, such as tris(acetylacetonate)(monophenanthroline)terbium(III) (abbreviated: [Tb(acac)3(Phen)]), are included. These are compounds that primarily emit green phosphorescence and have an emission peak at 500 nm to 600 nm. In addition, organometallic iridium complexes having a pyrimidine backbone are particularly desirable because their reliability and luminescence efficiency are remarkably high.

[0061] Other examples include organometallic iridium complexes having a pyrimidine backbone, such as (diisobutyrylmetaneto)bis[4,6-bis(3-methylphenyl)pyrimidineto iridium(III) (abbreviated: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidineto](dipivaloylmetaneto)iridium(III) (abbreviated: [Ir(5mdppm)2(dpm)]), and bis[4,6-di(naphthalene-1-yl)pyrimidineto(dipivaloylmetaneto)iridium(III) (abbreviated: [Ir(d1npm)2(dpm)]). Organometallic iridium complexes having a pyrazine backbone, such as (acetylacetonato)bis(2,3,5-triphenylpyrazineto)iridium(III) (abbreviated: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazineto)(dipivaloylmetaneto)iridium(III) (abbreviated: [Ir(tppr)2(dpm)]), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinatoiridium(III) (abbreviated: [Ir(Fdpq)2(acac)]), tris(1-phenylisoquinolinato-N,C 2' )Iridium(III) (abbreviated: [Ir(piq)3]) and bis(1-phenylisoquinolinato-N,C 2' Organometallic iridium complexes having a pyridine backbone such as iridium(III) acetylacetonate (abbreviated: [Ir(piq)2(acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviated: [PtOEP]), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedioto)(monophenantrolline)europium(III) (abbreviated: [Eu(DBM)3(Phen)]) and tris[1-(2-tenoyl)-3,3,3-trifluoroacetonato(monophenantrolline)europium(III) (abbreviated: [Eu(TTA)3(Phen)]). These compounds emit red phosphorescence with an emission peak at 600 nm to 700 nm. Additionally, organometallic iridium complexes having a pyrazine backbone can provide high-color intensity red emission.

[0062] In addition to the above phosphorescent compound, known phosphorescent materials may be selected and used.

[0063] Examples of TADF materials include fullerenes, their derivatives, acridins, their derivatives, and eosin derivatives. Also, metal-containing porphyrins such as porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) may be included. Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), ethioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP), represented by the following structural formulas.

[0064] [Chemical Formula 1]

[0065]

[0066] or represented by the following structural formulas: 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazole-11-yl)-1,3,5-triazine (abbreviated: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazine-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviated: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated: PCCzPTzn), 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated: Heterocyclic compounds having one or both of a π-electron excess heteroaromatic ring and a π-electron deficiency heteroaromatic ring, such as PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridin)phenyl]sulfone (abbreviation: DMAC-DPS), or 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA), may be used. These heterocyclic compounds are desirable because they exhibit excellent electron transport and hole transport due to the π-electron-excess heteroaromatic ring and the π-electron-deficient heteroaromatic ring. Among the frameworks having a π-electron-deficient heteroaromatic ring, the pyridine framework, the diazine framework (pyrimidine framework, pyrazine framework, and pyridazine framework), and the triazine framework are desirable because they have high stability and reliability. In particular, the benzofuropyrimidine framework, benzothienopyrimidine framework, benzofuropyrazine framework, and benzothienopyrazine framework are desirable because they have high water solubility and reliability.Among the frameworks having a π-electron excess heteroaromatic ring, the acridine framework, phenoxazine framework, phenothiazine framework, furan framework, thiophene framework, and pyrrole framework are preferred because they have high stability and reliability, and it is desirable to include at least one of these frameworks. As a furan framework, a dibenzofuran framework is preferred. As a thiophene framework, a dibenzothiophene framework is preferred. As a pyrrole framework, an indole framework, a carbazole framework, an indolocarbazole framework, a bicarbazole framework, and a 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole framework are particularly preferred. In addition, materials in which a π-electron-excess heteroaromatic ring is directly bonded to a π-electron-deficient heteroaromatic ring are particularly desirable because both the electron-donating capacity of the π-electron-excess heteroaromatic ring and the electron-accepting capacity of the π-electron-deficient heteroaromatic ring are enhanced, and the energy difference between the S1 and T1 levels is reduced, allowing for high-efficiency thermal activation delayed fluorescence. Furthermore, instead of a π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group, such as a cyano group, may be used. As the π-electron-excess backbone, an aromatic amine backbone or a phenazine backbone may be used. As a π-electron deficient backbone, a xanthen backbone, a thioxanthenide backbone, an oxadiazole backbone, a triazole backbone, an imidazole backbone, an anthraquinone backbone, a backbone containing boron such as phenylborane or borantrene, an aromatic ring or heteroaromatic ring having a cyano group or a nitrile group such as benzonitrile or cyanobenzene, a carbonyl backbone such as benzophenone, a phosphine oxide backbone, or a sulfone backbone may be used. As described above, a π-electron deficient backbone and a π-electron excess backbone may be used instead of at least one of a π-electron deficient heteroaromatic ring and a π-electron excess heteroaromatic ring.

[0067] [Chemical Formula 2]

[0068]

[0069] It is preferable that the TADF material be a substance represented by any of the following general formulas (G1) to (G11).

[0070] [Chemical Formula 3]

[0071]

[0072] [Chemical Formula 4]

[0073]

[0074] Also, in the above general formula (G1), R 1 to R 5 At least one of them represents a cyanotype, and R 1 to R 5 At least one of the following represents a substituted or unsubstituted 9-carbazolyl group, a substituted or unsubstituted 1,2,3,4-tetrahydro-9-carbazolyl group, a substituted or unsubstituted 1-indoleyl group, or a substituted or unsubstituted diarylamino group, and R 1 to R 5 The remainder each independently represent a hydrogen atom or a substituent.

[0075] In the above general formula (G2), R 11 and R 12 Each represents independently a hydrogen atom or any substituent, and A represents at least one heteroaryl group that may have a substituent or at least one arylamino group that may have a substituent, which is a substituent bonded to the carbon at the 4th position of the pyridine ring directly or through an aromatic group.

[0076] In the above general formula (G3), Ar 1 or Ar 3 Each represents an aryl group, and Ar 1 or Ar 3 At least one of them represents an aryl group substituted with a dibenzo-1,4-oxazine or a dibenzo-1,4-thiazine.

[0077] In the above general formula (G4), X represents a disubstituted amino group substituted with a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or an aromatic hydrocarbon group, an aromatic heterocyclic group, and a condensed polycyclic aromatic group. Y represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms that may have a substituent, a cycloalkyl group having 5 to 10 carbon atoms that may have a substituent, a straight-chain or branched-chain alkenyl group having 2 to 6 carbon atoms that may have a substituent, a straight-chain or branched-chain alkyloxy group having 1 to 6 carbon atoms that may have a substituent, a cycloalkyloxy group having 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, a substituted or unsubstituted aryloxy group, or a disubstituted amino group substituted with a group selected from an aromatic hydrocarbon group, an aromatic heterocyclic group, and a condensed polycyclic aromatic group. R 21 , R 22 , and R 25 to R 28R may be the same or different and each independently represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms that may have a substituent, a straight-chain or branched-chain alkenyl group having 2 to 6 carbon atoms that may have a substituent, a straight-chain or branched-chain alkyloxy group having 1 to 6 carbon atoms that may have a substituent, a cycloalkyloxy group having 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, a substituted or unsubstituted aryloxy group, or a disubstituted amino group substituted with a group selected from an aromatic hydrocarbon group, an aromatic heterocyclic group, and a condensed polycyclic aromatic group. 21 , R 22 , and R 25 to R 28 They may be bonded to each other through single bonds, substituted or unsubstituted methylene groups, oxygen atoms, or sulfur atoms to form a ring.

[0078] In the above general formula (G5), A 1 To A 3 Each represents an independently substituted or unsubstituted dibenzofuranyl group.

[0079] In the above general formula (G6), R 31 to R 34 and a to h each independently represent a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C6 to C20 aryl group, or an amino group.

[0080] In the above general formula (G7), R 41 to R 48 Each independently represents a hydrogen atom or an electron donor, and R 41 to R48 At least one of them represents an electron donor. R 49 to R 56 Each independently represents a hydrogen atom or an electron-withdrawing group other than a triazino group, and R 49 to R 56 At least one of them represents an electron absorber other than a triazino. Also, R 41 to R 56 Of these, 11 to 14 represent hydrogen atoms.

[0081] In the above general formula (G8), R 61 to R 68 and R 77 Each independently represents a hydrogen atom or an electron donor, and R 61 to R 68 and R 77 At least one of them represents an electron donor. R 69 to R 76 Each represents independently a hydrogen atom or an electron-withdrawing group that does not possess a lone pair of electrons at the α position. Z represents a single bond or =C=Y, and Y represents S, C(CN2), or C(COOH)2. Additionally, if Z represents a single bond, R 69 to R 76 At least one of them represents an electron withdrawer that does not have a non-covalent electron pair at the α position.

[0082] In the above general formula (G9), ring α is an aromatic ring that is condensed with an adjacent ring at any position and is represented by formula (g9-1), and ring β is a hetero ring that is condensed with an adjacent ring at any position and is represented by formula (g9-2). Ar in formula (G9) and Ar in formula (g9-2) each independently represent an aromatic hydrocarbon group or an aromatic hetero ring group. R in formula (G9) and R in formula (g9-1) each independently represent hydrogen, or a monovalent substituent selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an alkylamino group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, an ar-al-gil group having 7 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, and a substituted or unsubstituted 6-membered aromatic heterocyclic group having 3 to 30 carbon atoms, and adjacent substituents may be bonded to each other to form a ring. n represents an integer from 1 to 4.

[0083] In the above general formula (G10), X 1 , X 2 , and X 3X represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms that may have a substituent, a straight-chain or branched-chain alkyl group having 5 to 10 carbon atoms that may have a substituent, a straight-chain or branched-chain alkenyl group having 2 to 6 carbon atoms that may have a substituent, a straight-chain or branched-chain alkyloxy group having 1 to 6 carbon atoms that may have a substituent, a cycloalkyloxy group having 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, a substituted or unsubstituted aryloxy group, or a disubstituted amino group substituted with a group selected from an aromatic hydrocarbon group, an aromatic heterocyclic group, and a condensed polycyclic aromatic group. 1 , X 2 , and X 3 At least one of them represents a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or a disubstituted amino group substituted with a group selected from an aromatic hydrocarbon group, an aromatic heterocyclic group, and a condensed polycyclic aromatic group. Ar 4 represents a substituted or unsubstituted divalent aromatic hydrocarbon group, a substituted or unsubstituted divalent heteroaromatic hydrocarbon group, or a substituted or unsubstituted divalent condensed polycyclic aromatic hydrocarbon group. R 81 to R 86 and R 89 to R 94represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, a nitro group, a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms that may have a substituent, a cycloalkyl group having 5 to 10 carbon atoms that may have a substituent, a straight-chain or branched-chain alkenyl group having 2 to 6 carbon atoms that may have a substituent, a straight-chain or branched-chain alkyloxy group having 1 to 6 carbon atoms that may have a substituent, a cycloalkyloxy group having 5 to 10 carbon atoms that may have a substituent, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, a substituted or unsubstituted aryloxy group, or a disubstituted amino group substituted with a group selected from an aromatic hydrocarbon group, an aromatic heterocyclic group, and a condensed polycyclic aromatic group. R 81 to R 86 and R 89 to R 94 They may be bonded to each other through single bonds, substituted or unsubstituted methylene groups, oxygen atoms, or sulfur atoms to form a ring.

[0084] In the above general formula (G11), R 101 to R 104 Each represents an independently substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted cycloalkyl group, and R 105 to R 106 Each represents an independently substituted or unsubstituted alkyl group, and R 107 , R 108 , and R 109Each represents an independently substituted or unsubstituted aryl group or a substituted or unsubstituted alkyl group, n1 to n4 and n7 each represent an integer selected from 0 to 4, n5 and n6 each represent an integer selected from 0 to 3, and n8 and n9 each represent an integer selected from 0 to 5. R 101 to R 109 If n1 to n9, each corresponding to , are each integers of 2 or more, then multiple R 101 They may be the same or different from each other, and this is R 102 to R 109 The same applies to .

[0085] In addition, TADF materials are materials that have a small difference between the S1 and T1 levels and possess the ability to convert triplet excitation energy into singlet excitation energy through inverse term crossing. Therefore, TADF materials can use a small amount of thermal energy to upconvert triplet excitation energy into singlet excitation energy (i.e., inverse term crossing) and efficiently generate a singlet excited state. In addition, triplet excitation energy can be converted into luminescence.

[0086] Excited complexes that form excited states with two types of materials have a very small difference between the S1 and T1 levels and function as TADF materials capable of converting triplet excitation energy into singlet excitation energy.

[0087] The phosphorescence spectrum observed at low temperatures (e.g., 77K to 10K) is used as an indicator of the T1 level. When the energy level of the wavelength of the line obtained by extrapolating the tangent to the fluorescence spectrum at the short-wavelength tail is the S1 level and the energy level of the wavelength of the line obtained by extrapolating the tangent to the phosphorescence spectrum at the short-wavelength tail is the T1 level, it is preferable that the difference between the S1 level and the T1 level of the TADF material is 0.3 eV or less, and more preferable that it is 0.2 eV or less.

[0088] When using TADF material as a luminescent center material, it is desirable that the S1 and T1 levels of the host material are higher than the S1 and T1 levels of the TADF material.

[0089] As a host material for the light-emitting layer, various carrier transport materials such as materials with electron transport, materials with hole transport, and TADF materials can be used.

[0090] Examples of materials with hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated: NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated: TPD), 4,4'-bis[N-(spiro-9,9'-bifluorene-2-yl)-N-phenylamino]biphenyl (abbreviated: BSPB), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (abbreviated: BPAFLP), 4-phenyl-3'-(9-phenylfluorene-9-yl)triphenylamine (abbreviated: mBPAFLP), and 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated: PCBA1BP). Aromatic compounds such as 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]fluorene-2-amine (abbreviated: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviated: PCBASF) Compounds having an amine backbone, compounds having a carbazole backbone such as 1,3-bis(N-carbazolyl)benzene (abbreviated: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviated: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated: CzTP), and 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated: PCCP), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophen) (abbreviated: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorene-9-yl)phenyl]dibenzothiophen (abbreviated: DBTFLP-III), and Compounds having a thiophene backbone such as 4-[4-(9-phenyl-9H-fluorene-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated: DBTFLP-IV), and 4,4',4''-(benzene-1,3,Compounds having a furan backbone, such as 5-triyl)tri(dibenzofuran) (abbreviated: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluorene-9-yl)phenyl]phenyl}dibenzofuran (abbreviated: mmDBFFLBi-II), are included. Among the above materials, compounds having an aromatic amine backbone and compounds having a carbazole backbone are preferred because they have high reliability and high hole transportability, which contribute to the reduction of the driving voltage. In addition, organic compounds cited as examples of the second organic compounds may also be used.

[0091] Examples of materials with electron transport properties include metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviated: BeBq2), bis(2-methyl-8-quinolinoleato)(4-phenylphenolato)aluminum(III) (abbreviated: BAlq), bis(8-quinolinoleato)zinc(II) (abbreviated: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviated: ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviated: ZnBTZ), and 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and Heterocyclic compounds having a polyazole backbone such as 2-{4-[9,10-di(naphthalene-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviation: ZADN), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), Heterocyclic compounds having a diazine backbone such as 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviated: 4,6mPnP2Pm), and 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviated: 4,6mDBTP2Pm-II), and 3,5-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviated: 35DCzPPy) and 1,3,Heterocyclic compounds having a pyridine backbone, such as 5-tri[3-(3-pyridyl)phenyl]benzene (abbreviated: TmPyPB), are included. Among the above materials, heterocyclic compounds having a diazine backbone and heterocyclic compounds having a pyridine backbone are preferred because of their high reliability. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) backbone exhibit excellent electron transport properties, which contribute to the reduction of the driving voltage.

[0092] As a TADF material that can be used as a host material, the above-described material may be used. When a TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted into singlet excitation energy through inverse term crossing and transferred to the light-emitting center material, thereby increasing the luminescence efficiency of the light-emitting device. Here, the TADF material functions as an energy donor, and the light-emitting center material functions as an energy acceptor.

[0093] This is very effective when the above-mentioned luminescent center material is a fluorescent material. In this case, to achieve high luminescence efficiency, it is desirable that the S1 level of the TADF material is higher than the S1 level of the fluorescent material. In addition, it is desirable that the T1 level of the TADF material is higher than the S1 level of the fluorescent material. Therefore, it is desirable that the T1 level of the TADF material is higher than the T1 level of the fluorescent material.

[0094] It is desirable to use a TADF material that emits light whose wavelength overlaps with the wavelength of the absorption band on the lowest energy side of the fluorescent material, because the excitation energy is smoothly transferred from the TADF material to the fluorescent material and luminescence can be obtained efficiently.

[0095] Furthermore, in order to efficiently generate singlet excitation energy from triplet excitation energy through inverse term crossing, it is desirable for carrier recombination to occur in the TADF material. It is also desirable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent material. For this reason, it is desirable for the fluorescent material to have protecting groups around the emitting group (the framework that causes luminescence) of the fluorescent material. As protecting groups, it is desirable to use substituents that do not have π bonds and saturated hydrocarbons. Specific examples include alkyl groups having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3 to 10 carbon atoms, and trialkylsilyl groups having 3 to 10 carbon atoms. It is more desirable for the fluorescent material to have multiple protecting groups. Since substituents that do not have π bonds lack carrier transport performance, they can cause the emitting groups of the TADF material and the fluorescent material to move apart from each other with minimal influence on carrier transport or carrier recombination. Here, the emitting group refers to the atomic group (framework) that causes luminescence in the fluorescent material. The emitting group is preferably a backbone having π bonds, more preferably includes an aromatic ring, and even more preferably includes a condensed aromatic ring or a condensed heteroaromatic ring. Examples of condensed aromatic rings or condensed heteroaromatic rings include a phenanthrene backbone, a stilbene backbone, an acridone backbone, a phenoxazine backbone, and a phenothiazine backbone. Specifically, a fluorescent material having any of a naphthalene backbone, anthracene backbone, a fluorene backbone, a chrysene backbone, a triphenylene backbone, a tetracene backbone, a pyrene backbone, a perylene backbone, a coumarin backbone, a quinacridone backbone, and a naphthobisbenzofuran backbone is preferred because it has a high fluorescence quantum yield.

[0096] When using a fluorescent material as a luminescent core, it is preferable to use a material having an anthracene backbone as the host material. By using a material having an anthracene backbone as the host material for the fluorescent material, a luminescent layer with high luminescence efficiency and high durability can be obtained. Among materials having an anthracene backbone, materials having a diphenylanthracene backbone, particularly materials having a 9,10-diphenylanthracene backbone, are chemically stable, so they are preferred to be used as host materials. It is preferable for the host material to have a carbazole backbone because hole injection and hole transport properties are improved, and it is even more preferable for the host material to have a benzocarbazole backbone in which a benzene ring is further condensed to a carbazole because the HOMO level becomes about 0.1 eV shallower than that of carbazole, making it easier for holes to enter the host material. In particular, it is desirable for the host material to have a dibenzocarbazole backbone, as the HOMO level becomes about 0.1 eV shallower than that of carbazole, making it easier for holes to enter the host material, improving hole transportability, and increasing heat resistance. Therefore, as a host material, a material having both a 9,10-diphenylanthracene backbone and a carbazole backbone (or a benzocarbazole or dibenzocarbazole backbone) is more preferable. Additionally, from the perspective of the hole injection and hole transportability described above, a benzofluorene backbone or a dibenzofluorene backbone may be used instead of a carbazole backbone.Examples of these substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviated: PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviated: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviated: cgDBCzPA), and 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviated: 2mBnfPPA). 9-phenyl-10-{4-(9-phenyl-9H-fluorene-9-yl)biphenyl-4'-yl}anthracene (abbreviated: FLPPA), and 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated: αN-βNPAnth) are included. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred to be selected as they have excellent properties.

[0097] In addition, the host material may be a mixture of multiple types of materials, and when using a mixed host material, it is preferable to mix the electron transport material with the hole transport material. By mixing the electron transport material with the hole transport material, the transportability of the light-emitting layer (113) can be easily adjusted and the recombination region can be easily controlled. The weight ratio of the content of the hole transport material to the content of the electron transport material can be 1:19 to 19:1.

[0098] In addition, a phosphorescent material can be used as part of the mixed material. When a fluorescent material is used as the luminescent center material, the phosphorescent material can be used as an energy donor that supplies excitation energy to the fluorescent material.

[0099] An excited composite may be formed using these mixed materials. If these mixed materials are selected to form an excited composite that exhibits luminescence where the wavelength overlaps with the wavelength of the absorption band on the lowest energy side of the luminescent material, energy can be transferred smoothly, and luminescence can be obtained efficiently. Using such a structure is desirable because it also allows for a reduction in driving voltage.

[0100] In addition, at least one of the materials forming the excited complex may be a phosphorescent material. In this case, triplet excitation energy can be efficiently converted into singlet excitation energy through inverse inter-term crossing.

[0101] A combination of a material having electron transport and a material having hole transport, wherein the HOMO level is greater than or equal to the HOMO level of the material having electron transport, is desirable for efficiently forming an excited complex. Additionally, it is desirable that the LUMO level of the material having hole transport be greater than or equal to the LUMO level of the material having electron transport. Furthermore, the LUMO and HOMO levels of the materials can be derived from the electrochemical properties (reduction potential and oxidation potential) of the materials measured by cyclic voltammetry (CV).

[0102] The formation of an excited complex can be confirmed by the phenomenon observed by comparing the emission spectra of a material with hole transport and a material with electron transport, for example, a mixed film of these materials, in which the emission spectrum of the mixed film of these materials shifts toward the longer wavelength side (or has different peaks on the longer wavelength side) compared to the emission spectrum of each material. Alternatively, the formation of an excited complex can be confirmed by differences in transient response, such as the phenomenon in which the transient PL lifetime of the mixed film has a longer lifetime component or a larger proportion of the delay component than the transient PL lifetime of each material, observed by comparing the transient PL (photoluminescence) of the material with hole transport, the material with electron transport, and the mixed film of these materials. Transient PL can be read as transient EL (electroluminescence). That is, the formation of the excited complex can also be confirmed by the difference in transient response observed by comparing the transient EL of a material with hole transport, a material with electron transport, and a film of these materials.

[0103] The electron transport layer (114) is provided in contact with the light-emitting layer (113). The electron transport layer (114) comprises a seventh organic compound having electron transport properties and a HOMO level of -6.0 eV or higher. The seventh organic compound is an organic compound having electron transport properties and preferably comprises an anthracene backbone. The electron transport layer (114) may further comprise an eighth material which is an organic complex of an alkali metal or an alkaline earth metal. That is, the electron transport layer (114) may be formed as a single seventh organic compound, or as a mixed material comprising the seventh organic compound and another material, such as a mixed material of the seventh organic compound and the eighth material.

[0104] It is more preferable that the seventh organic compound comprises an anthracene skeleton and a heterocyclic skeleton, and it is preferable to use a nitrogen-containing five-membered ring skeleton as the heterocyclic skeleton. It is preferable that the seventh organic compound comprises a nitrogen-containing five-membered ring skeleton containing two heteroatoms in the ring, such as a pyrazol ring, an imidazole ring, an oxazole ring, or a thiazole ring.

[0105] Alternatively, as an organic compound having electron transportability that can be used as the seventh organic compound, any material that has electron transportability that can be used as a host material or an organic compound that can be used as a host material for a fluorescent material may be used.

[0106] The organic complex of an alkali metal or alkaline earth metal is preferably an organic complex of lithium, and in particular, it is preferably 8-hydroxyquinolinate lithium (abbreviated: Liq).

[0107] When the square root of the electric field strength [V / cm] is 600, the electron mobility of the material included in the electron transport layer (114) is 1×10 -7 cm 2 / Vs 5X10 or more -5 cm 2 It is desirable that / Vs be less than or equal to

[0108] In addition, when the square root of the electric field strength [V / cm] is 600, the electron mobility of the material included in the electron transport layer (114) is preferably lower than the electron mobility of the material included in the sixth organic compound or the light-emitting layer (113) when the square root of the electric field strength [V / cm] is 600. Since the amount of electron injection into the light-emitting layer can be controlled by lowering the electron transportability of the electron transport layer, it is possible to prevent the light-emitting layer from having an excess of electrons.

[0109] If the light-emitting layer has an excess of electrons, as shown in (A) of FIG. 2, the light-emitting region (113-1) is limited to a part, and a heavy burden is placed on that part, which accelerates deterioration. In addition, the light-emitting efficiency and lifespan are reduced as electrons pass through the light-emitting layer without recombining. In one embodiment of the present invention, by reducing the electron transportability of the electron transport layer (114), the light-emitting region (113-1) is expanded as shown in (B) of FIG. 2, and the burden on the material included in the light-emitting layer (113) is dispersed. Therefore, a light-emitting device with a long lifespan and high light-emitting efficiency can be provided.

[0110] There may be cases where the degradation curve of a light-emitting device having such a structure, obtained by driving tests at a constant current density, has a maximum value. In other words, the shape of the degradation curve of a light-emitting device according to one embodiment of the present invention may have a portion in which the brightness increases over time. A light-emitting device exhibiting such degradation behavior can offset the rapid degradation at the beginning of driving, known as initial degradation, through the aforementioned increase in brightness. Therefore, it is possible to make the light-emitting device with less initial degradation and a very long lifespan.

[0111] The derivative of such a degradation curve having a maximum value is zero in some parts. In other words, a light-emitting device according to one embodiment of the present invention having a portion of the degradation curve where the derivative is zero can have smaller initial degradation and a very long lifespan.

[0112] This phenomenon is thought to occur due to recombination in a non-radiative recombination region (114-1) that does not contribute to light emission, as illustrated in (A) of FIG. 3. In the light-emitting device of the present invention having the structure described above, the hole injection barrier is small during the initial driving phase and the electron transportability of the electron transport layer (114) is relatively low, so a light-emitting region (113-1) (i.e., a recombination region) is formed on the side of the electron transport layer (114). In addition, because the HOMO level of the seventh organic compound included in the electron transport layer (114) is relatively high at -6.0 eV or higher, some holes also reach the electron transport layer (114) and recombination occurs in the electron transport layer (114), thus forming a non-radiative recombination region (114-1). This phenomenon may also occur when the difference in HOMO levels between the sixth organic compound and the seventh organic compound is 0.2 eV or less.

[0113] As the operating time elapses and the carrier balance changes, the light-emitting region (113-1) (recombination region) moves toward the hole transport layer (112) as shown in (B) of FIG. 3. When the non-radiative recombination region (114-1) is reduced, the brightness increases because the energy of the recombined carriers can be efficiently contributed to light emission. This increase in brightness offsets the rapid decrease in brightness at the beginning of operation of the light-emitting device, known as initial degradation. Therefore, the light-emitting device can have less initial degradation and a longer operating life.

[0114] If initial degradation can be reduced, the problem of burn-in, which is still discussed as a major weakness of organic EL devices, and the time and effort required for pre-shipment aging to reduce the problem can be significantly reduced.

[0115] A light-emitting device according to one embodiment of the present invention having the above-described structure can be made to have a long lifespan.

[0116] (Embodiment 2)

[0117] Next, specific examples of the structure and materials of the light-emitting device described above will be explained. As described above, a light-emitting device according to one embodiment of the present invention includes an EL layer (103) having a plurality of layers located between a pair of electrodes (anode (101) and cathode (102)). In the EL layer (103), a hole injection layer (111), a first hole transport layer (112-1), a second hole transport layer (112-2), a light-emitting layer (113), and an electron transport layer are provided from the anode (101) side.

[0118] There are no special limitations on other layers included in the EL layer (103), and various layers such as a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a carrier blocking layer, an exciton blocking layer, and a charge generation layer may be employed.

[0119] The anode (101) is preferably formed using any of the following: a metal, an alloy, a conductive compound, or a mixture thereof, which has a large work function (specifically 4.0 eV or more). Specific examples include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). These conductive metal oxide films are generally formed by sputtering, but may also be formed by applying the sol-gel method. In some examples of the formation method, indium zinc oxide is deposited by sputtering using a target obtained by adding 1 wt% to 20 wt% of zinc oxide to indium oxide. In addition, a film of indium oxide (IWZO) containing tungsten oxide and zinc oxide can be formed by sputtering using a target to which 0.5 wt% to 5 wt% of tungsten oxide and 0.1 wt% to 1 wt% of zinc oxide are added to indium oxide. Alternatively, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or nitrides of metallic materials (e.g., titanium nitride) can be used. Graphene may also be used. Furthermore, although representative materials for forming the anode have been listed above, since a composite material of an organic compound having hole transport properties and a material exhibiting electron acceptance properties for this organic compound is used in the hole injection layer (111) of one embodiment of the present invention, the electrode material can be selected regardless of the work function.

[0120] A stacked structure of two types of EL layers (103) is described, comprising the structure shown in (A) of FIG. 1, which includes an electron injection layer (115) in addition to a hole injection layer (111), a first hole transport layer (112-1), a second hole transport layer (112-2), an emitting layer (113), and an electron transport layer (114), and the structure shown in (B) of FIG. 1, which includes a charge generation layer (116) in addition to a hole injection layer (111), a first hole transport layer (112-1), a second hole transport layer (112-2), an emitting layer (113), and an electron transport layer (114). The materials forming each layer are described in detail below.

[0121] As the hole injection layer (111), hole transport layer (112) (first hole transport layer (112-1) and second hole transport layer (112-2)), light-emitting layer (113), and electron transport layer (114) have been described in detail in Embodiment 1, their description will not be repeated. Please refer to the description of Embodiment 1.

[0122] Between the electron transport layer (114) and the cathode (102), a layer comprising an alkali metal, alkaline earth metal, or a compound thereof, such as lithium fluoride (LiF), cesium fluoride (CsF), or calcium fluoride (CaF2), may be provided as an electron injection layer (115). For example, a layer formed using an electride or a material having electron transport properties and comprising an alkali metal, alkaline earth metal, or a compound thereof may be used as the electron injection layer (115). Examples of electrides include a material in which electrons are added to calcium oxide or aluminum oxide at a high concentration.

[0123] Instead of the electron injection layer (115), a charge generation layer (116) may be provided between the electron transport layer (114) and the cathode (102) ((B) of FIG. 1). The charge generation layer (116) refers to a layer capable of injecting holes into the layer in contact with the cathode side of the charge generation layer (116) and electrons into the layer in contact with the anode side when a potential is applied. The charge generation layer (116) includes at least a p-type layer (117). The p-type layer (117) is preferably formed using any of the composite materials mentioned above as examples of materials that can be used for the hole injection layer (111). The p-type layer (117) may be formed by stacking a film containing the acceptor material described above and a film containing a hole transport material as materials included in the composite material. When a potential is applied to the p-type layer (117), electrons are injected into the electron transport layer (114), and holes are injected into the cathode (102) which functions as a cathode, so the light-emitting device operates.

[0124] Additionally, the charge generation layer (116) preferably includes an electronic relay layer (118) and / or an electronic injection buffer layer (119) in addition to the p-type layer (117).

[0125] The electronic relay layer (118) includes at least a material having electron transportability and has the function of preventing interaction between the electron injection buffer layer (119) and the p-type layer (117) and smoothly transporting electrons. It is preferable that the LUMO level of the material having electron transportability included in the electronic relay layer (118) be between the LUMO level of the electron accepting material in the p-type layer (117) and the LUMO level of the material included in the layer in contact with the charge generation layer (116) in the electron transport layer (114). As for specific values ​​of energy levels, it is preferable that the LUMO level of the material having electron transportability in the electronic relay layer (118) be -5.0 eV or higher, and more preferable that it be -5.0 eV or higher and -3.0 eV or lower. In addition, as the material having electron transportability in the electronic relay layer (118), it is preferable to use a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0126] A material with excellent electron injection properties may be used in the electron injection buffer layer (119). For example, alkali metals, alkaline earth metals, rare earth metals, or compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate)), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates) may be used.

[0127] When the electron injection buffer layer (119) includes a material having electron transport properties and a material having electron donor properties, in addition to alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)), organic compounds such as tetracyanapthacene (abbreviated as TTN), nickelocene, or decamethylnickelocene may be used as the material having electron donor properties. As the material having electron transport properties, a material similar to the material of the electron transport layer (114) described above may be used.

[0128] For the cathode (102), metals, alloys, electrically conductive compounds, or mixtures thereof with a small work function (specifically 3.8 eV or less) can be used. Specific examples of such cathode materials include alkali metals (e.g., lithium (Li) and cesium (Cs)), elements belonging to Group 1 and Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), alloys containing these elements (e.g., MgAg and AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these rare earth metals. However, if an electron injection layer is provided between the cathode (102) and the electron transport layer, various conductive materials such as Al, Ag, ITO, silicon, or indium oxide-tin oxide containing silicon oxide can be used for the cathode (102) regardless of the work function. Films of these conductive materials can be formed by dry processes such as vacuum deposition or sputtering, inkjet methods, or spin coating methods. Alternatively, a wet process using a sol-gel method or a wet process using a metal material paste may be used.

[0129] In addition, any of the various methods, regardless of whether it is a dry method or a wet method, can be used to form the EL layer (103). For example, vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, or spin coating may be used.

[0130] The electrodes or layers described above may be formed using other methods.

[0131] The structure of the layer provided between the anode (101) and the cathode (102) is not limited to the structure described above. In order to prevent extinguishing of light due to the proximity of the light-emitting region and the metal used in the electrode and carrier injection layer, it is preferable that the light-emitting region where holes and electrons recombine is located away from the anode (101) and the cathode (102).

[0132] In addition, so as to suppress energy transfer from excitons generated in the light-emitting layer, it is preferable that the hole transport layer and electron transport layer in contact with the light-emitting layer (113), and the carrier transport layer closer to the recombination region of the light-emitting layer (113), be formed using a material having a wider band gap than the light-emitting material of the light-emitting layer or the light-emitting material included in the light-emitting layer.

[0133] Next, with reference to (C) of FIG. 1, a form of a light-emitting device having a structure in which a plurality of light-emitting units are stacked (this form of the light-emitting device is also called a stacked light-emitting device or a tandem light-emitting device) will be described. This light-emitting device includes a plurality of light-emitting units between an anode and a cathode. One light-emitting unit has a structure approximately the same as the EL layer (103) shown in (A) of FIG. 1. In other words, the light-emitting device shown in (A) or (B) of FIG. 1 includes one light-emitting unit, and the light-emitting device shown in (C) of FIG. 1 includes a plurality of light-emitting units.

[0134] In (C) of FIG. 1, a first light-emitting unit (511) and a second light-emitting unit (512) are stacked between an anode (501) and a cathode (502), and a charge-generating layer (513) is provided between the first light-emitting unit (511) and the second light-emitting unit (512). The anode (501) and the cathode (502) correspond to the anode (101) and the cathode (102) shown in (A) of FIG. 1, respectively, and the material presented in the description of (A) of FIG. 1 may be used. In addition, the first light-emitting unit (511) and the second light-emitting unit (512) may have the same structure or different structures.

[0135] The charge generating layer (513) has the function of injecting electrons into one light-emitting unit and injecting holes into the other light-emitting unit when a voltage is applied between the positive electrode (501) and the negative electrode (502). That is, in (C) of FIG. 1, when a voltage is applied such that the potential of the positive electrode becomes higher than the potential of the negative electrode, the charge generating layer (513) injects electrons into the first light-emitting unit (511) and holes into the second light-emitting unit (512).

[0136] It is preferable that the charge generation layer (513) has a structure similar to the charge generation layer (116) described with reference to (B) of FIG. 1. Since the composite material of an organic compound and a metal oxide has excellent carrier injection and carrier transport properties, low voltage driving and low current driving can be realized. When the positive side of the light-emitting unit comes into contact with the charge generation layer (513), the charge generation layer (513) can also function as a hole injection layer of the light-emitting unit, so it is not necessary to provide a hole injection layer to the light-emitting unit.

[0137] When the charge generation layer (513) includes an electron injection buffer layer (119), the electron injection buffer layer (119) functions as an electron injection layer in the light-emitting unit on the positive side, so an electron injection layer does not need to be formed in the light-emitting unit on the positive side.

[0138] Although a light-emitting device having two light-emitting units has been described with reference to (C) of FIG. 1, one embodiment of the present invention may also be applied to a light-emitting device having three or more light-emitting units stacked. As with the light-emitting device according to the present embodiment, by partitioning a plurality of light-emitting units between a pair of electrodes with a charge generating layer (513), a long-life device capable of emitting light of high brightness at a low current density can be provided. A light-emitting device capable of being driven at a low voltage and having low power consumption can be provided.

[0139] By making the light emission colors of the light-emitting units different, light emission of a desired color can be obtained as a whole light-emitting device. For example, in a light-emitting device having two light-emitting units, if the light emission color of the first light-emitting unit is red and green and the light emission color of the second light-emitting unit is blue, white light can be emitted as a whole light-emitting device. A light-emitting device having three or more light-emitting units stacked can be a tandem device, for example, in which the first light-emitting unit includes a first blue light-emitting layer, the second light-emitting unit includes a yellow or yellow-green light-emitting layer and a red light-emitting layer, and the third light-emitting unit includes a second blue light-emitting layer. This tandem device can provide white light emission, similar to the light-emitting device.

[0140] The above-described layers and electrodes, such as the EL layer (103), the first light-emitting unit (511), the second light-emitting unit (512), and the charge-generating layer, can be formed by a deposition method (including vacuum deposition), a droplet discharge method (also called inkjet method), a coating method, or a gravure printing method. Low molecular weight materials, medium molecular weight materials (including oligomers and dendrimers), or high molecular weight materials may be included in the layers and electrodes.

[0141] (Embodiment 3)

[0142] In this embodiment, a light-emitting device including the light-emitting device described in Embodiment 1 and Embodiment 2 is described.

[0143] In this embodiment, a light-emitting device fabricated using the light-emitting device described in Embodiments 1 and 2 is described with reference to FIG. 4 (A) and (B). FIG. 4 (A) is a top view of the light-emitting device, and FIG. 4 (B) is a cross-sectional view taken along lines AB and CD of FIG. 4 (A). This light-emitting device controls the light emission of the light-emitting device and includes a driving circuit section (source line driving circuit) (601), a pixel section (602), and a driving circuit section (gate line driving circuit) (603), indicated by dashed lines. Reference numeral 604 indicates a sealing substrate, 605 indicates a sealing material, and 607 indicates a space surrounded by the sealing material (605).

[0144] Lead wiring (608) is wiring for transmitting signals input to source line driving circuit (601) and gate line driving circuit (603), and for receiving signals such as video signals, clock signals, start signals, and reset signals from a flexible printed circuit (FPC) (609) that functions as an external input terminal. Although only the FPC is shown here, a printed circuit board (PWB) may be mounted on the FPC. The light-emitting device in this specification includes not only the light-emitting device itself, but also a light-emitting device provided with an FPC or PWB.

[0145] Next, the cross-sectional structure is described with reference to (B) of FIG. 4. A driving circuit section and a pixel section are formed on the element substrate (610). Here, a source line driving circuit (601), which is the driving circuit section, and one pixel of the pixel section (602) are shown.

[0146] The device substrate (610) may be a substrate including glass, quartz, organic resin, metal, alloy, or semiconductor, or may be a plastic substrate formed of FRP (fiber reinforced plastic), PVF (polyvinyl fluoride), polyester, or acrylic.

[0147] The structure of the transistors used in the pixel and driving circuit is not particularly limited. For example, reverse staggered transistors may be used, or staggered transistors may be used. Additionally, top-gate or bottom-gate transistors may be used. The semiconductor material used for the transistor is not particularly limited, and for example, silicon, germanium, silicon carbide, or gallium nitride may be used. Alternatively, oxide semiconductors containing at least one of indium, gallium, and zinc, such as In-Ga-Zn metal oxides, may be used.

[0148] There are no specific limitations regarding the crystallinity of the semiconductor material used in the transistor, and amorphous semiconductors or crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or semiconductors containing partially crystalline regions) may be used. Using crystalline semiconductors is preferable as it can suppress the degradation of transistor characteristics.

[0149] Here, it is preferable to use oxide semiconductors for semiconductor devices such as transistors provided for pixels and driving circuits, and transistors used in touch sensors described later. In particular, it is preferable to use oxide semiconductors with a band gap wider than silicon. By using oxide semiconductors with a band gap wider than silicon, the off-state current of the transistor can be reduced.

[0150] It is preferable that the oxide semiconductor comprises at least indium (In) or zinc (Zn). It is more preferable that the oxide semiconductor comprises an oxide represented by an In-M-Zn-based oxide (where M represents a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0151] An oxide semiconductor that can be used in one embodiment of the present invention is described below.

[0152] Oxide semiconductors (metal oxides) are classified into single-crystal oxide semiconductors and non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include c-axis aligned crystalline oxide semiconductor (CAAC-OS), polycrystalline oxide semiconductor, nanocrystalline oxide semiconductor (nc-OS), amorphous-like oxide semiconductor (a-like OS), and amorphous oxide semiconductor.

[0153] CAAC-OS has a c-axis orientation, its nanocrystals are connected in the ab plane direction, and its crystal structure exhibits deformation. Furthermore, deformation refers to the region within the connected nanocrystals where the orientation of the lattice arrangement changes between a regular lattice region and another regular lattice region.

[0154] The shape of nanocrystals is fundamentally hexagonal, but it is not necessarily a regular hexagon; non-regular hexagons can also occur. Deformations may include pentagonal and heptagonal lattice arrangements. Furthermore, it is difficult to observe distinct grain boundaries even near the deformation of CAAC-OS. In other words, the formation of grain boundaries is suppressed because the lattice arrangement is deformed. This is because CAAC-OS allows for deformation due to factors such as the low density of oxygen atoms in the ab plane direction and changes in interatomic bond distances caused by the substitution of metal elements.

[0155] CAAC-OS tends to have a layered crystal structure (also referred to as a layered structure) in which a layer containing indium and oxygen (hereinafter referred to as the In layer) and a layer containing element M, zinc, and oxygen (hereinafter referred to as the (M, Zn) layer) are stacked. In addition, indium and element M can be substituted for each other, and if element M in the (M, Zn) layer is substituted with indium, the layer can be called the (In, M, Zn) layer. If indium in the In layer is substituted with element M, the layer can be called the (In, M) layer.

[0156] CAAC-OS is a highly crystalline oxide semiconductor. On the other hand, since it is difficult to observe distinct grain boundaries in CAAC-OS, a decrease in electron mobility caused by grain boundaries is unlikely to occur. However, the crystallinity of the oxide semiconductor may decrease due to the intrusion of impurities or the formation of defects. This is because CAAC-OS is [described as] impurities and defects (e.g., oxygen vacancies (V O This means that it is an oxide semiconductor with a small amount of (also called). Therefore, oxide semiconductors containing CAAC-OS are physically stable. Consequently, oxide semiconductors containing CAAC-OS are heat-resistant and highly reliable.

[0157] In nc-OS, minute regions (e.g., regions with a size of 1 nm or more and 10 nm or less, particularly regions with a size of 1 nm or more and 3 nm or less) have a periodic atomic arrangement. In nc-OS, there is no regularity of crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Consequently, depending on the analysis method, nc-OS may not be distinguishable from a-like OS or amorphous oxide semiconductors.

[0158] In addition, indium-gallium-zinc oxide (hereinafter IGZO), an oxide semiconductor containing indium, gallium, and zinc, may have a stable structure when formed into the aforementioned nanocrystals. In particular, since IGZO crystals tend not to grow in the atmosphere, a stable structure is obtained when IGZO is formed into small crystals (e.g., the aforementioned nanocrystals) rather than large crystals (here, crystals with a size of several mm or several cm).

[0159] a-like OS is an oxide semiconductor with a structure intermediate between nc-OS and amorphous oxide semiconductors. a-like OS has voids or low-density regions. That is, a-like OS has lower crystallinity compared to nc-OS and CAAC-OS.

[0160] Oxide semiconductors may have any of several structures exhibiting various and different characteristics. Two or more of amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, nc-OS, and CAAC-OS may be included in the oxide semiconductor according to one embodiment of the present invention.

[0161] Other than the above, a CAC-OS (cloud-aligned composite OS) may be used as an oxide semiconductor.

[0162] CAC-OS has a conductive function in part of the material and an insulating function in another part of the material, and as a whole, CAC-OS functions as a semiconductor. Furthermore, when CAC-OS is used in the semiconductor layer of a transistor, the conductive function allows electrons (or holes) that function as carriers to flow, while the insulating function prevents electrons that function as carriers from flowing. Through the complementary interaction of the conductive function and the insulating function, a switching function (on / off function) can be imparted to CAC-OS. In CAC-OS, each function can be maximized by separating the above functions.

[0163] Furthermore, CAC-OS includes conductive regions and insulating regions. The conductive regions possess the aforementioned conductive function, and the insulating regions possess the aforementioned insulating function. Additionally, within the material, the conductive regions and insulating regions may be separated at the nanoparticle level. Furthermore, within the material, the conductive regions and insulating regions may be unevenly distributed. Moreover, the boundaries of the conductive regions may become blurred, appearing as cloud-like connections.

[0164] In addition, in CAC-OS, the conductive region and the insulating region each have a size of 0.5 nm or more and 10 nm or less, preferably 0.5 nm or more and 3 nm or less, and may be dispersed within the material.

[0165] In addition, CAC-OS includes components having different band gaps. For example, CAC-OS includes a component having a wide gap due to an insulating region and a component having a narrow gap due to a conductive region. In this structure, when carriers are flowed, carriers mainly flow through the component having the narrow gap. Additionally, the component having the narrow gap complements the component having the wide gap, and carriers also flow through the component having the wide gap in conjunction with the component having the narrow gap. Therefore, when the above-described CAC-OS or CAC-metal oxide is used in the channel formation region of a transistor, high current driving capability in the on-state of the transistor, that is, high on-state current and high field-effect mobility can be obtained.

[0166] In other words, CAC-OS can also be called a matrix composite or a metal matrix composite.

[0167] By using the oxide semiconductor material described above in the semiconductor layer, it is possible to provide a highly reliable transistor in which variations in electrical characteristics are suppressed.

[0168] Since the off-state current of the transistor is low, the charge accumulated in the capacitive element through the transistor including the aforementioned semiconductor layer can be maintained for a long time. When such a transistor is used in a pixel, the operation of the driving circuit can be stopped while maintaining the gradation of the image displayed in each display area. As a result, an electronic device with very low power consumption can be obtained.

[0169] To ensure stable characteristics of the transistor, it is desirable to provide an underlayer. The underlayer can be formed in a single-layer or multilayer structure using an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film. The underlayer can be formed by sputtering, chemical vapor deposition (CVD) (e.g., plasma CVD, thermal CVD, or metal organic CVD), atomic layer deposition (ALD), coating, or printing. Additionally, it is not mandatory to provide an underlayer.

[0170] In addition, an FET (623) is shown as a transistor formed in the driving circuit portion (601). In addition, the driving circuit can be formed using any of various circuits, such as a CMOS circuit, a PMOS circuit, or an NMOS circuit. In this embodiment, a driver integrated type in which the driving circuit is formed on a substrate is shown, but it is not necessary to form the driving circuit on the substrate, and the driving circuit can be formed outside the substrate.

[0171] The pixel section (602) includes a plurality of pixels comprising a switching FET (611), a current control FET (612), and an anode (613) electrically connected to the drain of the current control FET (612). One embodiment of the present invention is not limited to this structure. The pixel section (602) may include a combination of three or more FETs and capacitive elements.

[0172] In addition, an insulating material (614) is formed by covering the end of the anode (613). Here, the insulating material (614) can be formed using positive photosensitive acrylic.

[0173] In order to improve the coverage of the EL layer formed later, the insulating material (614) is formed to have a curved surface with curvature at its upper or lower portion. For example, when positive photosensitive acrylic is used as the material for the insulating material (614), it is preferable that only the upper portion of the insulating material (614) has a curved surface with a radius of curvature (0.2 μm to 3 μm). As the insulating material (614), either a negative photosensitive resin or a positive photosensitive resin may be used.

[0174] An EL layer (616) and a cathode (617) are formed on the anode (613). Here, as the material used for the anode (613), it is preferable to use a material with a high work function. For example, a single layer such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% to 20 wt% zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film, a laminate of a titanium nitride film and a film containing aluminum as the main component, or a laminate of three layers of a titanium nitride film, a film containing aluminum as the main component, and a titanium nitride film may be used. The laminated structure enables low wiring resistance and good ohmic contact, and can function as a cathode.

[0175] The EL layer (616) is formed by any of the various methods, such as deposition using a deposition mask, inkjet method, and spin coating method. The EL layer (616) has the structure described in Embodiment 1 and Embodiment 2. As other materials included in the EL layer (616), low molecular weight compounds or high molecular weight compounds (including oligomers or dendrimers) may be used.

[0176] As a material used for the cathode (617) formed on the EL layer (616), it is preferable to use a material with a low work function (e.g., Al, Mg, Li, and Ca, or an alloy or compound thereof (MgAg, MgIn, or AlLi, etc.). When light generated from the EL layer (616) passes through the cathode (617), it is preferable to use a stack of a metal thin film and a transparent conductive film (e.g., ITO, indium oxide containing 2 wt% to 20 wt% zinc oxide, indium tin oxide containing silicon, or zinc oxide (ZnO)) as the cathode (617).

[0177] In addition, the light-emitting device is formed with an anode (613), an EL layer (616), and a cathode (617). The light-emitting device is the light-emitting device described in Embodiment 1 and Embodiment 2. In the light-emitting device of the present embodiment, the pixel portion comprising a plurality of light-emitting devices may include both the light-emitting device described in Embodiment 1 and Embodiment 2 and a light-emitting device having a different structure.

[0178] By bonding the sealing substrate (604) to the device substrate (610) with a sealing material (605), a light-emitting device (618) is provided in a space (607) surrounded by the device substrate (610), the sealing substrate (604), and the sealing material (605). The space (607) may be filled with a filler, an inert gas (such as nitrogen or argon), or a sealing material. It is preferable that a recess is provided in the sealing substrate and that a desiccant is provided in the recess, as this can suppress deterioration caused by the influence of moisture.

[0179] It is preferable to use an epoxy resin or glass frit for the sealing material (605). It is desirable that such materials do not allow moisture or oxygen to pass through as much as possible. As for the sealing substrate (604), a glass substrate, a quartz substrate, or a plastic substrate formed of FRP (fiber reinforced plastic), PVF (polyvinyl fluoride), polyester, or acrylic may be used.

[0180] Although not shown in (A) and (B) of FIG. 4, a protective film may be provided over the cathode. As the protective film, an organic resin film or an inorganic insulating film may be formed. The protective film may be formed to cover the exposed portion of the sealing material (605). The protective film may be provided to cover the surface and side of a pair of substrates and the exposed side of the sealing layer and insulating layer, etc.

[0181] The protective film can be formed using a material that does not easily allow impurities such as water to pass through. Therefore, the diffusion of impurities such as water from the outside to the inside can be effectively suppressed.

[0182] Oxides, nitrides, fluorides, sulfides, ternary compounds, metals, or polymers can be used as materials for the protective film. For example, the above material may include aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide, indium oxide, aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, gallium nitride, nitrides containing titanium and aluminum, oxides containing titanium and aluminum, oxides containing aluminum and zinc, sulfides containing manganese and zinc, sulfides containing cerium and strontium, oxides containing erbium and aluminum, or oxides containing yttrium and zirconium, etc.

[0183] It is desirable to form the protective film using a deposition method that provides good step coverage. One such method is atomic layer deposition (ALD). It is preferable to use a material for the protective film that can be deposited by the ALD method. By using the ALD method, defects such as cracks or pinholes can be reduced, and a dense protective film with uniform thickness can be formed. Furthermore, damage to the processed member during the formation of the protective film can be reduced.

[0184] By the ALD method, a uniform protective film with few defects can be formed on surfaces having complex uneven shapes, or on the top, side, and bottom surfaces of a touch panel.

[0185] As described above, a light-emitting device can be obtained using the light-emitting device described in Embodiment 1 and Embodiment 2.

[0186] The light-emitting device in the present embodiment can have good characteristics because it is manufactured using the light-emitting device described in Embodiments 1 and 2. Specifically, since the light-emitting device described in Embodiments 1 and 2 has a long lifespan, it can be made into a highly reliable light-emitting device. Since the light-emitting device using the light-emitting device described in Embodiments 1 and 2 has high luminous efficiency, it can realize a light-emitting device with low power consumption.

[0187] FIG. 5 (A) and (B) respectively illustrate examples of light-emitting devices that realize full-color display by forming a light-emitting device that emits white light and using a coloring layer (color filter), etc. FIG. 5 (A) illustrates a substrate (1001), a base insulating film (1002), a gate insulating film (1003), gate electrodes (1006, 1007, and 1008), a first interlayer insulating film (1020), a second interlayer insulating film (1021), a peripheral part (1042), a pixel part (1040), a driving circuit part (1041), an anode of the light-emitting device (1024W, 1024R, 1024G, and 1024B), a partition (1025), an EL layer (1028), a cathode of the light-emitting device (1029), a sealing substrate (1031), and a sealing material (1032), etc.

[0188] In FIG. 5 (A), a colored layer (red colored layer (1034R), green colored layer (1034G), and blue colored layer (1034B)) is provided on a transparent substrate (1033). A black matrix (1035) may also be provided. The transparent substrate (1033) provided with the colored layer and black matrix is ​​aligned and fixed to a substrate (1001). Additionally, the colored layer and black matrix (1035) are covered with an overcoat layer (1036). In FIG. 5 (A), light emitted from a part of the light-emitting layer does not pass through the colored layer, while light emitted from another part of the light-emitting layer passes through the colored layer. Since the light that does not pass through the colored layer is white, and the light that passes through any one of the colored layers is red, green, or blue, an image can be displayed using pixels of those four colors.

[0189] FIG. 5 (B) illustrates an example in which a colored layer (red colored layer (1034R), green colored layer (1034G), and blue colored layer (1034B)) is provided between the gate insulating film (1003) and the first interlayer insulating film (1020). As with this structure, the colored layer may be provided between the substrate (1001) and the sealing substrate (1031).

[0190] The light-emitting device described above is a light-emitting device having a structure (bottom emission structure) in which light is extracted from the side of the substrate (1001) where the FET is formed, but it may also be a light-emitting device having a structure (top emission structure) in which light is extracted from the side of the sealed substrate (1031). FIG. 6 is a cross-sectional view of a light-emitting device having a top emission structure. In this case, a substrate that does not transmit light may be used as the substrate (1001). The process up to the step of forming a connecting electrode that connects the FET and the positive electrode of the light-emitting device is performed in a manner similar to that of a light-emitting device having a bottom emission structure. Then, a third interlayer insulating film (1037) is formed to cover the electrode (1022). This insulating film may have a flattening function. The third interlayer insulating film (1037) may be formed using a material similar to the second interlayer insulating film, or it may be formed using any other known material.

[0191] Here, the anodes (1024W, 1024R, 1024G, and 1024B) of the three light-emitting devices are each anodes, but may be formed as cathodes. In addition, in the case of a light-emitting device having a top emission structure as shown in FIG. 6, it is preferable that the anode is a reflective electrode. The EL layer (1028) is formed to have a structure similar to the structure of the EL layer (103) described in Embodiments 1 and 2, which can obtain white light emission.

[0192] In the case of a top emission structure as illustrated in FIG. 6, it may be sealed with a sealing substrate (1031) provided with a coloring layer (red coloring layer (1034R), green coloring layer (1034G), and blue coloring layer (1034B)). The sealing substrate (1031) may be provided with a black matrix (1035) located between the pixels. The coloring layers (red coloring layer (1034R), green coloring layer (1034G), and blue coloring layer (1034B)) and the black matrix may be covered with an overcoat layer (1036). Additionally, a transparent substrate is used as the sealing substrate (1031). Here, an example of performing a full-color display using four colors—red, green, blue, and white—is shown, but there are no special limitations, and a full-color display using four colors—red, yellow, green, and blue—or three colors—red, green, and blue—may be performed.

[0193] In a light-emitting device having a top emission structure, a microcavity structure may be preferably adopted. A light-emitting device having a microcavity structure is formed by using a reflective electrode as the anode and a translucent / semireflective electrode as the cathode. The light-emitting device having a microcavity structure includes at least an EL layer that includes a light-emitting layer functioning as a light-emitting region between the reflective electrode and the translucent / semireflective electrode.

[0194] In addition, the reflective electrode has a reflectance of visible light of 40% to 100%, preferably 70% to 100%, and a resistivity of 1×10 -2 It is Ωcm or less. In addition, the semitransparent / semireflective electrode has a reflectance of visible light of 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10 -2 It is less than Ωcm.

[0195] Light emitted from the light-emitting layer included in the EL layer is reflected by the reflective electrode and the semi-transparent / semi-reflective electrode and resonates.

[0196] In the above-described light-emitting device, the optical path length between the reflective electrode and the semi-transparent / semi-reflective electrode can be changed by changing the thickness of the transparent conductive film, composite material, and carrier transport material. Therefore, light of a wavelength that resonates between the reflective electrode and the semi-transparent / semi-reflective electrode can be strengthened, and light of a wavelength that does not resonate between them can be weakened.

[0197] In addition, the light reflected back by the reflecting electrode (first reflected light) significantly interferes with the light (first incident light) that enters directly from the emissive layer to the semi-transparent / semi-reflective electrode. For this reason, it is desirable to adjust the optical path length between the reflecting electrode and the emissive layer to (2n-1)λ / 4 (where n is a natural number greater than or equal to 1 and λ is the wavelength of the color to be amplified). By adjusting the optical path length, the phases of the first reflected light and the first incident light can be aligned with each other, and the light emitted from the emissive layer can be further amplified.

[0198] In addition, in the above structure, the EL layer may include a plurality of light-emitting layers or a single light-emitting layer. The above-described tandem light-emitting device may be combined with a plurality of EL layers, and for example, the light-emitting device may have a structure in which a plurality of EL layers are provided, a charge-generating layer is provided between the EL layers, and each EL layer includes a plurality of light-emitting layers or a single light-emitting layer.

[0199] By having a microcavity structure, the luminescence intensity of a specific wavelength in the frontal direction can be increased, thereby reducing power consumption. In addition, in the case of a light-emitting device that displays an image using four subpixels of red, yellow, green, and blue colors, the brightness can be increased by yellow light emission, and since a microcavity structure suitable for the wavelength of the corresponding color can be adopted for each subpixel, it can be made into a light-emitting device with good characteristics.

[0200] The light-emitting device in the present embodiment can have good characteristics because it is manufactured using the light-emitting device described in Embodiments 1 and 2. Specifically, since the light-emitting device described in Embodiments 1 and 2 has a long lifespan, it can be made into a highly reliable light-emitting device. Since the light-emitting device using the light-emitting device described in Embodiments 1 and 2 has high luminous efficiency, it can realize a light-emitting device with low power consumption.

[0201] Although an active matrix light-emitting device was described above, a passive matrix light-emitting device will be described below. FIGS. 7 (A) and (B) illustrate a passive matrix light-emitting device manufactured using the present invention. FIGS. 7 (A) is a perspective view of the light-emitting device, and FIGS. 7 (B) is a cross-sectional view taken along line XY of FIGS. 7 (A). In FIGS. 7 (A) and (B), an EL layer (955) is provided between electrodes (952) and electrodes (956) on a substrate (951). The ends of the electrodes (952) are covered with an insulating layer (953). A partition layer (954) is provided on the insulating layer (953). The side walls of the partition layer (954) are inclined such that the distance between the two side walls gradually narrows toward the surface of the substrate. In other words, the cross-section taken along the direction of the short side of the partition layer (954) is trapezoidal, and the bottom side (the side of the trapezoid parallel to the surface of the insulating layer (953) and in contact with the insulating layer (953)) is shorter than the top side (the side of the trapezoid parallel to the surface of the insulating layer (953) and not in contact with the insulating layer (953). Therefore, by providing the partition layer (954), defects in the light-emitting device caused by static electricity, etc. Since the passive matrix light-emitting device also includes the light-emitting device described in Embodiment 1 and Embodiment 2, it can be made into a highly reliable light-emitting device or a light-emitting device with low power consumption.

[0202] In the light-emitting device described above, since a plurality of fine light-emitting devices arranged in a matrix can each be controlled, the light-emitting device can be suitably used as a display device for displaying images.

[0203] This embodiment can be freely combined with any of the other embodiments.

[0204] (Embodiment 4)

[0205] In this embodiment, an example of using the light-emitting device described in Embodiments 1 and 2 in a lighting device is described with reference to FIG. 8 (A) and (B). FIG. 8 (B) is a top view of a lighting device, and FIG. 8 (A) is a cross-sectional view taken along line ef of FIG. 8 (B).

[0206] In the lighting device of the present embodiment, an anode (401) is formed on a substrate (400) which is a support and has light transparency. The anode (401) corresponds to the anode (101) of embodiment 2. When light is extracted through the anode (401) side, the anode (401) is formed using a light-transmitting material.

[0207] A pad (412) for applying voltage to the negative electrode (404) is formed on the substrate (400).

[0208] An EL layer (403) is formed on the anode (401). The structure of the EL layer (403) corresponds, for example, to the structure of the EL layer (103) in Embodiments 1 and 2, or to a structure in which the light-emitting unit (511 and 512) and the charge-generating layer (513) are combined. Please refer to the above description for this structure.

[0209] An EL layer (403) is covered to form a cathode (404). The cathode (404) corresponds to the cathode (102) in embodiment 2. The cathode (404) is formed using a material with high reflectivity when light is extracted through the anode (401) side. Voltage is applied to the cathode (404) by connecting it to the pad (412).

[0210] As described above, the lighting device described in this embodiment includes a light-emitting device comprising an anode (401), an EL layer (403), and a cathode (404). Since the light-emitting device is a light-emitting device with high light-emitting efficiency, the lighting device in this embodiment can be a lighting device with low power consumption.

[0211] A lighting device is completed by fixing and sealing a substrate (400) provided with a light-emitting device having the above structure to a sealed substrate (407) using sealing materials (405 and 406). Only one of the sealing materials (405) and the sealing material (406) may be used. The internal sealing material (406) (not shown in (B) of FIG. 8) can be mixed with a desiccant so that it can adsorb moisture, thereby improving reliability.

[0212] If a portion of the pad (412) and the positive electrode (401) extends outside the sealing material (405 and 406), the extended portion may function as an external input terminal. An IC chip (420) with a converter mounted thereon may be provided on the external input terminal.

[0213] Since the lighting device described in this embodiment includes the light-emitting device described in Embodiments 1 and 2 as an EL element, it can be a highly reliable light-emitting device. In addition, it can be a light-emitting device with low power consumption.

[0214] (Embodiment 5)

[0215] In this embodiment, examples of electronic devices including the light-emitting devices described in Embodiments 1 and 2, respectively, are described. The light-emitting devices described in Embodiments 1 and 2 have a long lifespan and high reliability. As a result, the electronic devices described in this embodiment may each include a highly reliable light-emitting part.

[0216] Examples of electronic devices including the above-mentioned light-emitting device include television devices (also called TVs or television receivers), monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile telephones), portable game consoles, portable information terminals, audio playback devices, and large game machines such as pachinko machines. Specific examples of these electronic devices are presented below.

[0217] FIG. 9 (A) illustrates an example of a television device. In the television device, a display unit (7103) is included in a housing (7101). Here, the housing (7101) is supported by a stand (7105). An image can be displayed on the display unit (7103), and in the display unit (7103), light-emitting devices described in Embodiment 1 and Embodiment 2 are arranged in a matrix.

[0218] The television device can be operated by an operation switch of the housing (7101) or by a separate remote controller (7110). The channel and volume can be controlled by the operation key (7109) of the remote controller (7110), and the image displayed on the display unit (7103) can be controlled. Additionally, the remote controller (7110) may be provided with a display unit (7107) for displaying data output from the remote controller (7110).

[0219] In addition, the television device is provided with a receiver and a modem, etc. By using the receiver, general television broadcasts can be received. Furthermore, by connecting the television device to a wired or wireless communication network via a modem, unidirectional (from sender to receiver) or bidirectional (between sender and receiver or between receivers) data communication can be performed.

[0220] Figure 9 (B1) illustrates a computer comprising a main body (7201), a housing (7202), a display unit (7203), a keyboard (7204), an external connection port (7205), and a pointing device (7206). Additionally, this computer is manufactured using light-emitting devices arranged in a matrix in the display unit (7203), as described in Embodiments 1 and 2. The computer illustrated in Figure 9 (B1) may have the structure illustrated in Figure 9 (B2). In the computer illustrated in Figure 9 (B2), a second display unit (7210) is provided instead of the keyboard (7204) and the pointing device (7206). The second display unit (7210) is a touch panel, and input operations can be performed by touching an input display on the second display unit (7210) with a finger or a dedicated pen. The second display unit (7210) may also display an image other than the input display. The display unit (7203) may also be a touch panel. By connecting the two screens with a hinge, problems such as the screens being scratched or damaged during storage or transport of the computer can be prevented.

[0221] Figure 9 (C) illustrates an example of a mobile terminal. The mobile phone is provided with a display (7402) included in a housing (7401), an operation button (7403), an external connection port (7404), a speaker (7405), and a microphone (7406), etc. Additionally, the mobile phone has a display (7402) comprising a light-emitting device arranged in a matrix as described in Embodiments 1 and 2.

[0222] Data can be entered into the mobile terminal by touching the display (7402) of the mobile terminal shown in (C) of FIG. 9 with a finger or the like. In this case, operations such as making a phone call or composing an email can be performed by touching the display (7402) with a finger or the like.

[0223] The display unit (7402) mainly has three screen modes. The first mode is a display mode mainly for displaying images. The second mode is an input mode mainly for inputting information such as text. The third mode is a display and input mode that combines the two modes of the display mode and the input mode.

[0224] For example, when making a phone call or composing an email, characters displayed on the screen can be entered by selecting a character input mode for primarily entering characters on the display unit (7402). In this case, it is preferable to display a keyboard or number buttons over almost the entire screen of the display unit (7402).

[0225] If a detection device including a sensor such as a gyroscope or accelerometer for detecting tilt is provided within the mobile terminal, the direction of the display of the screen of the display unit (7402) can be automatically changed by determining the direction of the mobile terminal (whether the mobile terminal is positioned horizontally or vertically).

[0226] The screen mode is switched by touching the display unit (7402) or by operating the operation button (7403) of the housing (7401). Alternatively, the screen mode can be switched according to the type of image displayed on the display unit (7402). For example, if the signal of the image displayed on the display unit is a video data signal, the screen mode is switched to display mode. If the signal is a text data signal, the screen mode is switched to input mode.

[0227] Additionally, if no input by touch of the display unit (7402) is performed for a certain period while the signal detected by the light sensor of the display unit (7402) in input mode is detected, the screen mode may be controlled to switch from input mode to display mode.

[0228] The display unit (7402) may function as an image sensor. For example, personal authentication can be performed by capturing an image such as a palm or fingerprint when the display unit (7402) is touched with a palm or finger. Additionally, by providing a backlight or a sensing light source that emits near-infrared light to the display unit, images such as finger veins or palm veins can be captured.

[0229] In addition, the structure described in this embodiment can be appropriately combined with any of the structures described in embodiments 1 to 4.

[0230] As described above, since the range of application of the light-emitting device having the light-emitting device described in Embodiments 1 and 2 is wide, this light-emitting device can be applied to electronic devices in various fields. By using the light-emitting device described in Embodiments 1 and 2, highly reliable electronic devices can be obtained.

[0231] Figure 10 (A) is a schematic diagram illustrating an example of a robot vacuum cleaner.

[0232] The robot vacuum cleaner (5100) includes a display (5101) on its upper surface, a plurality of cameras (5102) on its side, a brush (5103), and an operation button (5104). Although not illustrated, the bottom surface of the robot vacuum cleaner (5100) is provided with a tire and a suction port, etc. Additionally, the robot vacuum cleaner (5100) includes various sensors such as an infrared sensor, an ultrasonic sensor, an accelerometer, a piezoelectric sensor, a light sensor, and a gyroscope sensor. The robot vacuum cleaner (5100) has wireless communication means.

[0233] The robot vacuum cleaner (5100) is self-propelled and detects dust (5120) and sucks up dust from a suction port provided on the bottom surface.

[0234] The robot vacuum cleaner (5100) can determine whether there are obstacles, such as walls, furniture, or steps, by analyzing an image captured by a camera (5102). If the robot vacuum cleaner (5100) detects an object (e.g., a wire) that can be caught on the brush (5103) through image analysis, it can stop the rotation of the brush (5103).

[0235] The display (5101) may display the remaining battery level and the amount of dust collected. The display (5101) may also display the path traveled by the robot vacuum cleaner (5100). The display (5101) may be a touch panel, or an operation button (5104) may be provided on the display (5101).

[0236] The robot vacuum cleaner (5100) can communicate with a portable electronic device (5140), such as a smartphone. The portable electronic device (5140) can display an image captured by the camera (5102). Therefore, the owner of the robot vacuum cleaner (5100) can monitor their room even when they are not at home. The owner can also check the display on the display (5101) using a portable electronic device (5140), such as a smartphone.

[0237] A light-emitting device according to one embodiment of the present invention can be used in a display (5101).

[0238] The robot (2100) illustrated in (B) of FIG. 10 includes a computing device (2110), an illuminance sensor (2101), a microphone (2102), an upper camera (2103), a speaker (2104), a display (2105), a lower camera (2106), an obstacle sensor (2107), and a moving mechanism (2108).

[0239] The microphone (2102) has the function of detecting the user's speaking voice and environmental sounds. The speaker (2104) also has the function of outputting voice. The robot (2100) can communicate with the user using the microphone (2102) and the speaker (2104).

[0240] The display (2105) has the function of displaying various types of information. The robot (2100) can display information desired by the user on the display (2105). The display (2105) may be provided with a touch panel. Additionally, the display (2105) may be a detachable information terminal, in which case charging and data communication can be performed by installing the display (2105) at a fixed position on the robot (2100).

[0241] The upper camera (2103) and the lower camera (2106) each have the function of capturing images of the surroundings of the robot (2100). The obstacle sensor (2107) can detect obstacles in the direction in which the robot (2100) moves forward using the movement mechanism (2108). The robot (2100) can move safely by recognizing the surrounding environment using the upper camera (2103), the lower camera (2106), and the obstacle sensor (2107). A light-emitting device according to one embodiment of the present invention can be used in a display (2105).

[0242] (C) of FIG. 10 illustrates an example of a goggle-type display. The goggle-type display includes, for example, a housing (5000), a display unit (5001), a speaker (5003), an LED lamp (5004), a connection terminal (5006), a sensor (5007) (a sensor having the function of measuring force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, longitude, electric field, current, voltage, power, radiation, flow rate, humidity, inclination, vibration, smell, or infrared), a microphone (5008), a display unit (5002), a support unit (5012), and an earphone (5013).

[0243] A light-emitting device according to one embodiment of the present invention can be used in the display unit (5001) and the display unit (5002).

[0244] FIG. 11 illustrates an example in which the light-emitting device described in Embodiments 1 and 2 is used in a table lamp, which is a lighting device. The table lamp shown in FIG. 11 includes a housing (2001) and a light source (2002), and the light source (2002) may use the lighting device described in Embodiment 3.

[0245] FIG. 12 illustrates an example of using the light-emitting device described in Embodiments 1 and 2 in an indoor lighting device (3001). Since the light-emitting device described in Embodiments 1 and 2 has high reliability, it can be used as a highly reliable lighting device. In addition, since the light-emitting device described in Embodiments 1 and 2 can be large in area, the light-emitting device can be used in a large-area lighting device. Furthermore, since the light-emitting device described in Embodiments 1 and 2 is thin, the light-emitting device can be used in a lighting device with reduced thickness.

[0246] The light-emitting device described in Embodiments 1 and 2 may be used on the windshield of a vehicle or on the dashboard of a vehicle. FIG. 13 illustrates an embodiment in which the light-emitting device described in Embodiments 1 and 2 is used on the windshield of a vehicle and on the dashboard of a vehicle. Each display area (5200 to 5203) includes the light-emitting device described in Embodiments 1 and 2.

[0247] The display area (5200 and 5201) is provided on the windshield of a vehicle and is a display device including each light-emitting device described in Embodiments 1 and 2. The light-emitting device described in Embodiments 1 and 2 may be a so-called see-through display device that allows viewing of the opposite side by including an anode and a cathode formed of electrodes having light transparency. Such a see-through display device may be provided on the windshield of a vehicle without obstructing the field of view. When a driving transistor, etc. is provided, it is preferable to use a light-transmitting transistor, such as an organic transistor comprising an organic semiconductor material or a transistor comprising an oxide semiconductor.

[0248] A display device including the light-emitting device described in Embodiments 1 and 2 is provided in a display area (5202) of the pillar portion. The display area (5202) can compensate for the view obscured by the pillar by displaying an image captured by an imaging unit provided on the vehicle body. Similarly, the display area (5203) provided on the dashboard portion can compensate for the view obscured by the vehicle body by displaying an image captured by an imaging unit provided on the exterior of the vehicle. Therefore, safety can be enhanced by eliminating unseen areas. Through images that compensate for areas the driver cannot see, the driver can easily and comfortably check for safety.

[0249] The display area (5203) can provide various information by displaying navigation data, speedometer, tachometer, mileage, fuel level, transmission gear status, and air conditioner settings. The content or layout of the display can be freely changed by the user. In addition, this information can also be displayed on the display area (5200 to 5203). The display area (5200 to 5203) may also be used as a lighting device.

[0250] FIGS. 14 (A) and (B) illustrate a foldable portable information terminal (5150). The foldable portable information terminal (5150) includes a housing (5151), a display area (5152), and a curved portion (5153). FIGS. 14 (A) illustrates an unfolded portable information terminal (5150). FIGS. 14 (B) illustrates a folded portable information terminal (5150). Although the display area (5152) of the portable information terminal (5150) is large, when folded, it is small in size and highly portable.

[0251] The display area (5152) can be folded in half by the bend (5153). The bend (5153) includes a flexible member and a plurality of supporting members. When the display area is folded, the flexible member is stretched and the bend (5153) has a radius of curvature of 2 mm or more, preferably 3 mm or more.

[0252] Additionally, the display area (5152) may be a touch panel (input / output device) including a touch sensor (input device). A light-emitting device according to one embodiment of the present invention may be used in the display area (5152).

[0253] FIGS. 15 (A) to (C) illustrates a foldable portable information terminal (9310). FIGS. 15 (A) illustrates an unfolded portable information terminal (9310). FIGS. 15 (B) illustrates a portable information terminal (9310) that is unfolded or folded. FIGS. 15 (C) illustrates a folded portable information terminal (9310). When the portable information terminal (9310) is unfolded, it has no seams and has a large display area, so it offers high visibility.

[0254] The display panel (9311) is supported by three housings (9315) connected to each other by a hinge (9313). Additionally, the display panel (9311) may be a touch panel (input / output device) including a touch sensor (input device). By folding the display panel (9311) at the hinge (9313) between two housings (9315), the portable information terminal (9310) can be reversibly deformed from an unfolded state to a folded state. A light-emitting device according to one embodiment of the present invention may be used in the display panel (9311).

[0255] (Example 1)

[0256] In this embodiment, a light-emitting device 1 according to one embodiment of the present invention is described. The structural formula of the organic compound used in the light-emitting device 1 is shown below.

[0257] [Chemical Formula 3]

[0258]

[0259] (Method for fabricating light-emitting device 1)

[0260] First, an anode (101) was formed by depositing indium tin oxide (ITSO) containing silicon oxide on a glass substrate by sputtering. The thickness of the anode (101) was set to 70 nm, and the electrode area was set to 2 mm x 2 mm.

[0261] Next, in the pretreatment for forming a light-emitting device on a substrate, the surface of the substrate was washed with water and calcined at 200°C for 1 hour, and then UV ozone treatment was performed for 370 seconds.

[0262] After that, 10 -4 The substrate was moved to a vacuum deposition apparatus with the pressure reduced to approximately Pa, vacuum firing was performed at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

[0263] Next, the substrate provided with the anode (101) was fixed to a substrate holder provided in a vacuum deposition apparatus such that the side on which the anode (101) is formed faces downward. Then, N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf) represented by structural formula (i) and NDP-9 (manufactured by Analysis Atelier Corporation, material serial number 1S20170124) were co-deposited to a thickness of 10 nm on the anode (101) using a resistance heating method such that the weight ratio of BBABnf to NDP-9 is 1:0.1, thereby forming a hole injection layer (111).

[0264] Next, a first hole transport layer (112-1) is formed by depositing BBABnf to a thickness of 20 nm on the hole injection layer (111), and then a second hole transport layer (112-2) is formed by depositing 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) (abbreviated: PCzN2), represented by structural formula (ii), to a thickness of 10 nm, thereby forming a hole transport layer (112). In addition, the second hole transport layer (112-2) also functions as an electron blocking layer.

[0265] Then, a light-emitting layer (113) was formed by co-depositing 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated: αN-βNPAnth) represented by structural formula (iii) and 3,10-bis[N-(9-phenyl-9H-carbazole-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated: 3,10PCA2Nbf(IV)-02) represented by structural formula (iv) to a thickness of 25 nm such that the weight ratio of αN-βNPAnth to 3,10PCA2Nbf(IV)-02 is 1:0.015.

[0266] Next, an electron transport layer (114) was formed on the light-emitting layer (113) by co-depositing 2-{4-[9,10-di(naphthalene-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviated as ZADN) represented by structural formula (v) and 8-hydroxyquinolinate lithium (abbreviated as Liq) represented by structural formula (vi) to a thickness of 25 nm such that the weight ratio of ZADN to Liq is 1:0.9.

[0267] After forming the electron transport layer (114), an electron injection layer (115) was formed by depositing Liq to a thickness of 1 nm. Then, a cathode (102) was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting device 1 of the present embodiment was fabricated.

[0268] The structure of light-emitting device 1 is listed in the table below.

[0269] [Table 1]

[0270]

[0271] The HOMO level, LUMO level, and electron mobility of the organic compound used in this example are listed in the table below. The electron mobility was measured when the square root of the electric field strength [V / cm] was 600.

[0272] [Table 2]

[0273]

[0274] The light-emitting device was sealed using a glass substrate inside a glove box containing a nitrogen atmosphere to prevent exposure to the atmosphere (a sealing material was applied around the device, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing). The initial characteristics and reliability of the light-emitting device were measured. The measurements were also performed at room temperature.

[0275] Figure 16 shows the luminance-current density characteristics of light-emitting device 1. Figure 17 shows the current efficiency-luminance characteristics. Figure 18 shows the luminance-voltage characteristics. Figure 19 shows the current-voltage characteristics. Figure 20 shows the external quantum efficiency-luminance characteristics. Figure 21 shows the emission spectrum. Table 3 shows approximately 1000 cd / m² 2 The main characteristics of the light-emitting device 1 at the luminance of were shown.

[0276] [Table 3]

[0277]

[0278] Looking at FIGS. 16 to 21 and Table 3, it can be seen that the light-emitting device 1 according to one embodiment of the present invention is a blue light-emitting device with good characteristics.

[0279] Fig. 22 is 50 mA / cm 2 This is a graph showing the change in brightness with respect to driving time at the current density. As shown in FIG. 22, the brightness maintains about 90% of the initial brightness even after 600 hours have elapsed. Accordingly, it was found that the decrease in brightness with driving time is particularly small, and the light-emitting device 1 according to one embodiment of the present invention has a very long lifespan.

[0280] In the degradation curve of light-emitting device 1, the brightness drops once and then rises. That is, the degradation curve has a maximum value. Light-emitting device 1, which exhibits such degradation behavior, has a very long lifespan.

[0281] (Example 2)

[0282] In this embodiment, a light-emitting device 2 according to one embodiment of the present invention is described. The structural formula of the organic compound used in the light-emitting device 2 is shown below.

[0283] [Chemical Formula 4]

[0284]

[0285] (Method for fabricating light-emitting device 2)

[0286] First, an anode (101) was formed by depositing indium tin oxide (ITSO) containing silicon oxide on a glass substrate by sputtering. The thickness of the anode (101) was set to 70 nm, and the electrode area was set to 2 mm x 2 mm.

[0287] Next, in the pretreatment for forming a light-emitting device on a substrate, the surface of the substrate was washed with water and calcined at 200°C for 1 hour, and then UV ozone treatment was performed for 370 seconds.

[0288] After that, 10 -4 The substrate was moved to a vacuum deposition apparatus with the pressure reduced to approximately Pa, vacuum firing was performed at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

[0289] Next, the substrate provided with the anode (101) was fixed to a substrate holder provided in a vacuum deposition apparatus such that the side on which the anode (101) is formed faces downward. Then, N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf) represented by structural formula (i) and NDP-9 (manufactured by Analysis Atelier Corporation, material serial number 1S20170124) were co-deposited to a thickness of 10 nm on the anode (101) using a resistance heating method such that the weight ratio of BBABnf to NDP-9 is 1:0.1, thereby forming a hole injection layer (111).

[0290] Next, a first hole transport layer (112-1) is formed by depositing BBABnf to a thickness of 20 nm on the hole injection layer (111), and then a second hole transport layer (112-2) is formed by depositing 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) (abbreviated: PCzN2), represented by structural formula (ii), to a thickness of 10 nm, thereby forming a hole transport layer (112). In addition, the second hole transport layer (112-2) also functions as an electron blocking layer.

[0291] Then, a light-emitting layer (113) was formed by co-depositing 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviated: cgDBCzPA) represented by structural formula (vii) and N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviated: 1,6BnfAPrn-03) represented by structural formula (viii) to a thickness of 25 nm such that the weight ratio of cgDBCzPA to 1,6BnfAPrn-03 is 1:0.03.

[0292] Next, an electron transport layer (114) was formed on the light-emitting layer (113) by co-depositing 2-{4-[9,10-di(naphthalene-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviated as ZADN) represented by structural formula (v) and 8-hydroxyquinolinate lithium (abbreviated as Liq) represented by structural formula (vi) to a thickness of 25 nm such that the weight ratio of ZADN to Liq is 1:1.

[0293] After forming the electron transport layer (114), an electron injection layer (115) was formed by depositing Liq to a thickness of 1 nm. Then, a cathode (102) was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting device 2 of the present embodiment was fabricated.

[0294] The structure of light-emitting device 2 is listed in the table below.

[0295] [Table 4]

[0296]

[0297] The HOMO level, LUMO level, and electron mobility of the organic compound used in this example are listed in the table below. The electron mobility was measured when the square root of the electric field strength [V / cm] was 600.

[0298] [Table 5]

[0299]

[0300] The light-emitting device was sealed using a glass substrate inside a glove box containing a nitrogen atmosphere to prevent exposure to the atmosphere (a sealing material was applied around the device, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing). The initial characteristics and reliability of the light-emitting device were measured. The measurements were also performed at room temperature.

[0301] Figure 23 shows the luminance-current density characteristics of light-emitting device 2. Figure 24 shows the current efficiency-luminance characteristics. Figure 25 shows the luminance-voltage characteristics. Figure 26 shows the current-voltage characteristics. Figure 27 shows the external quantum efficiency-luminance characteristics. Figure 28 shows the emission spectrum. Table 6 shows approximately 1000 cd / m² 2 The main characteristics of the light-emitting device 2 at the luminance of were shown.

[0302] [Table 6]

[0303]

[0304] Looking at FIGS. 23 to 28 and Table 6, it can be seen that the light-emitting device 2 according to one embodiment of the present invention is a blue light-emitting device with good characteristics.

[0305] Fig. 29 is 50 mA / cm 2This is a graph showing the change in brightness with respect to driving time at the current density. As shown in FIG. 29, the brightness maintains more than 97% of the initial brightness even after 300 hours have elapsed. Accordingly, it was found that the decrease in brightness with driving time is particularly small, and the light-emitting device 2 according to one embodiment of the present invention has a very long lifespan.

[0306] In the degradation curve of light-emitting device 2, the brightness drops once and then rises. From this, it can be seen that the degradation curve has a maximum value. Light-emitting device 2, which exhibits such degradation behavior, has less initial degradation and a very long lifespan.

[0307] (Example 3)

[0308] In this embodiment, a light-emitting device 3 according to one embodiment of the present invention is described. The structural formula of the organic compound used in the light-emitting device 3 is shown below.

[0309] [Chemical Formula 5]

[0310]

[0311] (Method for fabricating light-emitting device 3)

[0312] First, an anode (101) was formed by depositing indium tin oxide (ITSO) containing silicon oxide on a glass substrate by sputtering. The thickness of the anode (101) was set to 70 nm, and the electrode area was set to 2 mm x 2 mm.

[0313] Next, in the pretreatment for forming a light-emitting device on a substrate, the surface of the substrate was washed with water and calcined at 200°C for 1 hour, and then UV ozone treatment was performed for 370 seconds.

[0314] After that, 10 -4 The substrate was moved to a vacuum deposition apparatus with the pressure reduced to approximately Pa, vacuum firing was performed at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

[0315] Next, the substrate provided with the anode (101) was fixed to a substrate holder provided in a vacuum deposition apparatus such that the side on which the anode (101) is formed faces downward. Then, N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf) represented by structural formula (i) and NDP-9 (manufactured by Analysis Atelier Corporation, material serial number 1S20170124) were co-deposited to a thickness of 10 nm on the anode (101) using a resistance heating method such that the weight ratio of BBABnf to NDP-9 is 1:0.1, thereby forming a hole injection layer (111).

[0316] Next, a first hole transport layer (112-1) is formed by depositing BBABnf to a thickness of 20 nm on the hole injection layer (111), and then a second hole transport layer (112-2) is formed by depositing 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) (abbreviated: PCzN2), represented by structural formula (ii), to a thickness of 10 nm, thereby forming a hole transport layer (112). In addition, the second hole transport layer (112-2) also functions as an electron blocking layer.

[0317] Then, a light-emitting layer (113) was formed by co-depositing 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviated: cgDBCzPA) represented by structural formula (vii) and 3,10-bis[N-(9-phenyl-9H-carbazole-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated: 3,10PCA2Nbf(IV)-02) represented by structural formula (iv) to a thickness of 25 nm such that the weight ratio of cgDBCzPA to 3,10PCA2Nbf(IV)-02 is 1:0.015.

[0318] Next, an electron transport layer (114) was formed on the light-emitting layer (113) by co-depositing 2-{4-[9,10-di(naphthalene-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviated as ZADN) represented by structural formula (v) and 8-hydroxyquinolinate lithium (abbreviated as Liq) represented by structural formula (vi) to a thickness of 25 nm such that the weight ratio of ZADN to Liq is 1:1.

[0319] After forming the electron transport layer (114), an electron injection layer (115) was formed by depositing Liq to a thickness of 1 nm. Then, a cathode (102) was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting device 3 of the present embodiment was fabricated.

[0320] The structure of light-emitting device 3 is listed in the table below.

[0321] [Table 7]

[0322]

[0323] The HOMO level, LUMO level, and electron mobility of the organic compound used in this example are listed in the table below. The electron mobility was measured when the square root of the electric field strength [V / cm] was 600.

[0324] [Table 8]

[0325]

[0326] The light-emitting device was sealed using a glass substrate inside a glove box containing a nitrogen atmosphere to prevent exposure to the atmosphere (a sealing material was applied around the device, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing). The initial characteristics and reliability of the light-emitting device were measured. The measurements were also performed at room temperature.

[0327] Figure 30 shows the luminance-current density characteristics of light-emitting device 3. Figure 31 shows the current efficiency-luminance characteristics. Figure 32 shows the luminance-voltage characteristics. Figure 33 shows the current-voltage characteristics. Figure 34 shows the external quantum efficiency-luminance characteristics. Figure 35 shows the emission spectrum. In Table 9, approximately 1000 cd / m² 2 The main characteristics of the light-emitting device 3 at the luminance of were shown.

[0328] [Table 9]

[0329]

[0330] Looking at FIGS. 30 to 35 and Table 9, it can be seen that the light-emitting device 3 according to one embodiment of the present invention is a blue light-emitting device with good characteristics.

[0331] Fig. 36 is 50 mA / cm 2 This is a graph showing the change in brightness with respect to driving time at the current density. As shown in FIG. 36, it was found that the light-emitting device 3 according to one embodiment of the present invention maintains more than 94% of the initial brightness even after 300 hours have elapsed, and thus has a very long lifespan and a particularly small decrease in brightness with driving time.

[0332] In the degradation curve of light-emitting device 3, the brightness decreases and then increases. From this, it can be seen that the degradation curve has a maximum value. Light-emitting device 3, which exhibits such degradation behavior, has less initial degradation and a very long lifespan.

[0333] (Example 4)

[0334] In this embodiment, a light-emitting device 4 according to one embodiment of the present invention is described. The structural formula of the organic compound used in the light-emitting device 4 is shown below.

[0335] [Chemical Formula 6]

[0336]

[0337] (Method for fabricating light-emitting device 4)

[0338] First, an alloy film of silver (Ag), palladium (Pd), and copper (Cu), i.e., an APC (Ag-Pd-Cu) film, was formed to a thickness of 100 nm by sputtering as a reflective electrode, and then an anode (101) was formed by forming a film of indium tin oxide (ITSO) containing silicon oxide to a thickness of 85 nm by sputtering as a transparent electrode. The area of ​​the electrode is 4 mm 2 It was made (2mm x 2mm).

[0339] Next, in the pretreatment for forming a light-emitting device on a substrate, the surface of the substrate was washed with water and calcined at 200°C for 1 hour, and then UV ozone treatment was performed for 370 seconds.

[0340] After that, 10 -4 The substrate was moved to a vacuum deposition apparatus with the pressure reduced to approximately Pa, vacuum firing was performed at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

[0341] Next, the substrate provided with the anode (101) was fixed to a substrate holder provided in a vacuum deposition apparatus such that the side on which the anode (101) is formed faces downward. Then, N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf) represented by structural formula (i) and NDP-9 (manufactured by Analysis Atelier Corporation, material serial number 1S20170124) were co-deposited to a thickness of 10 nm on the anode (101) using a resistance heating method such that the weight ratio of BBABnf to NDP-9 is 1:0.05, thereby forming a hole injection layer (111).

[0342] Next, a first hole transport layer (112-1) is formed by depositing BBABnf to a thickness of 25 nm on the hole injection layer (111), and then a second hole transport layer (112-2) is formed by depositing 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) (abbreviated: PCzN2), represented by structural formula (ii), to a thickness of 10 nm, thereby forming a hole transport layer (112). In addition, the second hole transport layer (112-2) also functions as an electron blocking layer.

[0343] Then, a light-emitting layer (113) was formed by co-depositing 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated: αN-βNPAnth) represented by structural formula (iii) and 3,10-bis[N-(9-phenyl-9H-carbazole-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated: 3,10PCA2Nbf(IV)-02) represented by structural formula (iv) to a thickness of 25 nm such that the weight ratio of αN-βNPAnth to 3,10PCA2Nbf(IV)-02 is 1:0.015.

[0344] Next, an electron transport layer (114) was formed on the light-emitting layer (113) by co-depositing 2-{4-[9,10-di(naphthalene-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviated as ZADN) represented by structural formula (v) and 8-hydroxyquinolinate lithium (abbreviated as Liq) represented by structural formula (vi) to a thickness of 25 nm such that the weight ratio of ZADN to Liq is 1:1.

[0345] After forming the electron transport layer (114), an electron injection layer (115) was formed by depositing Liq to a thickness of 1 nm. A cathode (102) was formed by depositing it to a thickness of 15 nm so that the volume ratio of silver (Ag) to magnesium (Mg) is 1:0.1. Thus, a light-emitting device 4 was fabricated. Since the cathode (102) is a semi-transparent / semi-reflective electrode having the function of reflecting light and transmitting light, the light-emitting device 4 of this embodiment is a top emission device in which light is extracted through the cathode (102). On the cathode (102), 1,3,5-tri(dibenzothiophen-4-yl)-benzene (abbreviated: DBT3P-II), represented by structural formula (ix), was deposited to a thickness of 80 nm, thereby improving the extraction efficiency.

[0346] The structure of the light-emitting device 4 is listed in the table below.

[0347] [Table 10]

[0348]

[0349] The HOMO level, LUMO level, and electron mobility of the organic compound used in this example are listed in the table below. The electron mobility was measured when the square root of the electric field strength [V / cm] was 600.

[0350] [Table 11]

[0351]

[0352] The light-emitting device was sealed using a glass substrate inside a glove box containing a nitrogen atmosphere to prevent exposure to the atmosphere (a sealing material was applied around the device, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing). The initial characteristics and reliability of the light-emitting device 4 were measured. The measurements were also performed at room temperature.

[0353] Figure 42 shows the luminance-current density characteristics of light-emitting device 4. Figure 43 shows the current efficiency-luminance characteristics. Figure 44 shows the luminance-voltage characteristics. Figure 45 shows the current-voltage characteristics. Figure 46 shows the external quantum efficiency-luminance characteristics. Figure 47 shows the emission spectrum. In Table 12, approximately 1000 cd / m² 2 The main characteristics of the light-emitting device 4 at the luminance of were shown.

[0354] [Table 12]

[0355]

[0356] Looking at FIGS. 42 to 47 and Table 12, it can be seen that the light-emitting device 4 according to one embodiment of the present invention is a blue light-emitting device with good characteristics.

[0357] Fig. 48 shows an initial luminance of 1300 cd / m 2 This shows the change in brightness of the light-emitting device with respect to driving time under conditions where the current density is constant. As shown in FIG. 48, it was found that the light-emitting device 4 according to one embodiment of the present invention maintains about 95% of the initial brightness even after 1,000 hours have elapsed, so the decrease in brightness with driving time is small and it is a light-emitting device with a long lifespan.

[0358] (Example 5)

[0359] In this embodiment, a light-emitting device 5 according to one embodiment of the present invention is described. The structural formula of the organic compound used in the light-emitting device 5 is shown below.

[0360] [Chemical Formula 7]

[0361]

[0362] (Method for fabricating light-emitting device 5)

[0363] First, an anode (101) was formed by depositing indium tin oxide (ITSO) containing silicon oxide on a glass substrate by sputtering. The thickness of the anode (101) was set to 70 nm, and the electrode area was set to 2 mm x 2 mm.

[0364] Next, in the pretreatment for forming a light-emitting device on a substrate, the surface of the substrate was washed with water and calcined at 200°C for 1 hour, and then UV ozone treatment was performed for 370 seconds.

[0365] After that, 10 -4 The substrate was moved to a vacuum deposition apparatus with the pressure reduced to approximately Pa, vacuum firing was performed at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

[0366] Next, the substrate provided with the anode (101) was fixed to a substrate holder provided in a vacuum deposition apparatus such that the side on which the anode (101) is formed faces downward. Then, N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf) represented by structural formula (i) and NDP-9 (manufactured by Analysis Atelier Corporation, material serial number 1S20170124) were co-deposited to a thickness of 10 nm on the anode (101) using a resistance heating method such that the weight ratio of BBABnf to NDP-9 is 1:0.1, thereby forming a hole injection layer (111).

[0367] Next, a first hole transport layer (112-1) is formed by depositing BBABnf to a thickness of 20 nm on the hole injection layer (111), and then a second hole transport layer (112-2) is formed by depositing 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) (abbreviated as PCzN2), represented by structural formula (ii), to a thickness of 80 nm, thereby forming a hole transport layer (112). In addition, the second hole transport layer (112-2) also functions as an electron blocking layer.

[0368] and 9-[(3'-dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated: 9mDBtBPNfpr) represented by structural formula (x), N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-bis(9,9-dimethyl-9H-fluorene-2-yl)amine (abbreviated: PCBFF) represented by structural formula (xi), and bis[4,6-dimethyl-2-(7-(2-methylpropyl)-2-quinolinyl-κN)phenyl-κC](2,4-pentanedio-κ) represented by structural formula (xii). 2 A light-emitting layer (113) was formed by co-depositing iridium (III) (abbreviated as RS003) to a thickness of 65 nm such that the weight ratio of 9mDBtBPNfpr to PCBFF to RS003 was 0.5:0.5:0.05.

[0369] Next, an electron transport layer (114) was formed on the light-emitting layer (113) by co-depositing 2-{4-[9,10-di(naphthalene-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviated as ZADN) represented by structural formula (v) and 8-hydroxyquinolinate lithium (abbreviated as Liq) represented by structural formula (vi) to a thickness of 20 nm such that the weight ratio of ZADN to Liq is 1:1.

[0370] After forming the electron transport layer (114), an electron injection layer (115) was formed by depositing Liq to a thickness of 1 nm. Then, a cathode (102) was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting device 5 of the present embodiment was fabricated.

[0371] The structure of light-emitting device 5 is listed in the table below.

[0372] [Table 13]

[0373]

[0374] The HOMO level, LUMO level, and electron mobility of the organic compound used in this example are listed in the table below. The electron mobility was measured when the square root of the electric field strength [V / cm] was 600.

[0375] [Table 14]

[0376]

[0377] The light-emitting device was sealed using a glass substrate inside a glove box containing a nitrogen atmosphere to prevent exposure to the atmosphere (a sealing material was applied around the device, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing). The initial characteristics and reliability of the light-emitting device were measured. The measurements were also performed at room temperature.

[0378] Figure 49 shows the luminance-current density characteristics of light-emitting device 5. Figure 50 shows the current efficiency-luminance characteristics. Figure 51 shows the luminance-voltage characteristics. Figure 52 shows the current-voltage characteristics. Figure 53 shows the external quantum efficiency-luminance characteristics. Figure 54 shows the emission spectrum. Table 15 shows approximately 1000 cd / m² 2 The main characteristics of the light-emitting device 5 at the luminance of were shown.

[0379] [Table 15]

[0380]

[0381] Looking at FIGS. 49 to 54 and Table 15, it can be seen that the light-emitting device 5 according to one embodiment of the present invention is a red light-emitting device with good characteristics.

[0382] Fig. 55 is 75 mA / cm 2This is a graph (degradation curve) showing the change in brightness with respect to driving time at the current density. As shown in FIG. 55, the brightness maintains more than 99% of the initial brightness even after 100 hours have elapsed. Accordingly, it was found that the decrease in brightness with driving time is particularly small, and the light-emitting device 5 according to one embodiment of the present invention has a very long lifespan. Because it has a characteristic shape in that it has a maximum value in the degradation curve, the light-emitting device 5 can be made to have a very long lifespan by exhibiting the above degradation behavior.

[0383] (Example 6)

[0384] In this embodiment, a light-emitting device 6 according to one embodiment of the present invention is described. The structural formula of the organic compound used in the light-emitting device 6 is shown below.

[0385] [Chemical Formula 8]

[0386]

[0387] (Method for fabricating light-emitting device 6)

[0388] First, an anode (101) was formed by depositing indium tin oxide (ITSO) containing silicon oxide on a glass substrate by a sputtering method. The thickness of the anode (101) was set to 70 nm, and the electrode area was 4 mm 2 It was made (2mm x 2mm).

[0389] Next, in the pretreatment for forming a light-emitting device on a substrate, the surface of the substrate was washed with water and calcined at 200°C for 1 hour, and then UV ozone treatment was performed for 370 seconds.

[0390] After that, 10 -4 The substrate was moved to a vacuum deposition apparatus with the pressure reduced to approximately Pa, vacuum firing was performed at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

[0391] Next, the substrate provided with the anode (101) was fixed to a substrate holder provided in a vacuum deposition apparatus such that the side on which the anode (101) is formed faces downward. Then, N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf) represented by structural formula (i) and NDP-9 (manufactured by Analysis Atelier Corporation, material serial number 1S20170124) were co-deposited to a thickness of 10 nm on the anode (101) using a resistance heating method such that the weight ratio of BBABnf to NDP-9 is 1:0.1, thereby forming a hole injection layer (111).

[0392] Next, a first hole transport layer (112-1) is formed by depositing BBABnf to a thickness of 15 nm on the hole injection layer (111), and then a second hole transport layer (112-2) is formed by depositing 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) (abbreviated: PCzN2), represented by structural formula (ii), to a thickness of 40 nm, thereby forming a hole transport layer (112). In addition, the second hole transport layer (112-2) also functions as an electron blocking layer.

[0393] And 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated: 8BP-4mDBtPBfpm) represented by structural formula (xiii), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated: PCCP) represented by structural formula (xiv), and [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviated: [Ir(ppy)2(mdppy)]) represented by structural formula (xv), the weight ratio of 8BP-4mDBtPBfpm to PCCP to [Ir(ppy)2(mdppy)] A light-emitting layer (113) was formed by co-depositing with a thickness of 45 nm so that the ratio becomes 0.4:0.6:0.1.

[0394] Next, an electron transport layer (114) was formed on the light-emitting layer (113) by co-depositing 2-{4-[9,10-di(naphthalene-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviated as ZADN) represented by structural formula (v) and 8-hydroxyquinolinate lithium (abbreviated as Liq) represented by structural formula (vi) to a thickness of 25 nm such that the weight ratio of ZADN to Liq is 1:0.9.

[0395] After forming the electron transport layer (114), an electron injection layer (115) was formed by depositing Liq to a thickness of 1 nm. Then, a cathode (102) was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting device 6 of the present embodiment was fabricated.

[0396] The structure of the light-emitting device 6 is listed in the table below.

[0397] [Table 16]

[0398]

[0399] The HOMO level, LUMO level, and electron mobility of the organic compound used in this example are listed in the table below. The electron mobility was measured when the square root of the electric field strength [V / cm] was 600.

[0400] [Table 17]

[0401]

[0402] The light-emitting device was sealed using a glass substrate inside a glove box containing a nitrogen atmosphere to prevent exposure to the atmosphere (a sealing material was applied around the device, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing). The initial characteristics and reliability of the light-emitting device were measured. The measurements were also performed at room temperature.

[0403] Figure 56 shows the luminance-current density characteristics of light-emitting device 6. Figure 57 shows the current efficiency-luminance characteristics. Figure 58 shows the luminance-voltage characteristics. Figure 59 shows the current-voltage characteristics. Figure 60 shows the external quantum efficiency-luminance characteristics. Figure 61 shows the emission spectrum. Table 18 shows approximately 1000 cd / m² 2 The main characteristics of the light-emitting device 6 at the luminance of were shown.

[0404] [Table 18]

[0405]

[0406] Looking at FIGS. 56 to 61 and Table 18, it can be seen that the light-emitting device 6 according to one embodiment of the present invention is a green light-emitting device with good characteristics.

[0407] Fig. 62 is 50 mA / cm 2 This is a graph showing the change in brightness with respect to driving time at the current density. As shown in FIG. 62, the brightness maintains more than 80% of the initial brightness even after 200 hours have elapsed. Accordingly, it was found that the decrease in brightness with driving time is particularly small, and the light-emitting device 6 according to one embodiment of the present invention has a very long lifespan.

[0408] (Example 7)

[0409] In this embodiment, a light-emitting device 7 according to one embodiment of the present invention is described. The structural formula of the organic compound used in the light-emitting device 7 is shown below.

[0410] [Chemical Formula 9]

[0411]

[0412] (Method for fabricating light-emitting device 7)

[0413] First, an anode (101) was formed by depositing indium tin oxide (ITSO) containing silicon oxide on a glass substrate by sputtering. The thickness of the anode (101) was set to 70 nm, and the electrode area was set to 2 mm x 2 mm.

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

[0415] After that, 10 -4 The substrate was moved to a vacuum deposition apparatus with the pressure reduced to approximately Pa, vacuum firing was performed at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

[0416] Next, the substrate provided with the anode (101) was fixed to a substrate holder provided in a vacuum deposition apparatus such that the side on which the anode (101) is formed faces downward. Then, N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf) represented by structural formula (i) and NDP-9 (manufactured by Analysis Atelier Corporation, material serial number 1S20170124) were co-deposited to a thickness of 10 nm on the anode (101) using a resistance heating method such that the weight ratio of BBABnf to NDP-9 is 1:0.1, thereby forming a hole injection layer (111).

[0417] Next, a first hole transport layer (112-1) is formed by depositing BBABnf to a thickness of 55 nm on the hole injection layer (111), and then a second hole transport layer (112-2) is formed by depositing 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) (abbreviated: PCzN2), represented by structural formula (ii), to a thickness of 30 nm, thereby forming a hole transport layer (112). In addition, the second hole transport layer (112-2) also functions as an electron blocking layer.

[0418] and 9-[(3'-dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated: 9mDBtBPNfpr) represented by structural formula (x), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviated: PCBBiF) represented by structural formula (xvi), and represented by structural formula (xvii) bis{4,6-dimethyl-2-[5-(5-cyano-2-methylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptaneto-κ 2 A light-emitting layer (113) was formed by co-depositing iridium(III) (abbreviated as [Ir(dmdppr-m5CP)2(dpm)]) to a thickness of 60 nm such that the weight ratio of 9mDBtBPNfpr to PCBBiF to [Ir(dmdppr-m5CP)2(dpm)] was 0.8:0.2:0.1.

[0419] Next, an electron transport layer (114) was formed on the light-emitting layer (113) by co-depositing 2-{4-[9,10-di(naphthalene-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviated as ZADN) represented by structural formula (v) and 8-hydroxyquinolinate lithium (abbreviated as Liq) represented by structural formula (vi) to a thickness of 25 nm such that the weight ratio of ZADN to Liq is 1:0.9.

[0420] After forming the electron transport layer (114), an electron injection layer (115) was formed by depositing Liq to a thickness of 1 nm. Then, a cathode (102) was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting device 7 of the present embodiment was fabricated.

[0421] The structure of the light-emitting device 7 is listed in the table below.

[0422] [Table 19]

[0423]

[0424] The HOMO level, LUMO level, and electron mobility of the organic compound used in this example are listed in the table below. The electron mobility was measured when the square root of the electric field strength [V / cm] was 600.

[0425] [Table 20]

[0426]

[0427] The light-emitting device was sealed using a glass substrate inside a glove box containing a nitrogen atmosphere to prevent exposure to the atmosphere (a sealing material was applied around the device, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing). The initial characteristics and reliability of the light-emitting device were measured. The measurements were also performed at room temperature.

[0428] Figure 63 shows the luminance-current density characteristics of light-emitting device 7. Figure 64 shows the current efficiency-luminance characteristics. Figure 65 shows the luminance-voltage characteristics. Figure 66 shows the current-voltage characteristics. Figure 67 shows the external quantum efficiency-luminance characteristics. Figure 68 shows the emission spectrum. In Table 21, approximately 1000 cd / m² 2 The main characteristics of the light-emitting device 7 at the luminance of were shown.

[0429] [Table 21]

[0430]

[0431] Looking at FIGS. 63 to 68 and Table 21, it can be seen that the light-emitting device 7 according to one embodiment of the present invention is a red light-emitting device with good characteristics.

[0432] Fig. 69 is 75 mA / cm 2This is a graph showing the change in brightness with respect to driving time at the current density. As shown in FIG. 69, the brightness maintains more than 90% of the initial brightness even after 400 hours have elapsed. Accordingly, it was found that the decrease in brightness with driving time is particularly small, and the light-emitting device 7 according to one embodiment of the present invention has a very long lifespan.

[0433] (Example 8)

[0434] In this embodiment, a light-emitting device 8 and a light-emitting device 9 according to one embodiment of the present invention will be described. The structural formulas of the organic compounds used in light-emitting device 8 and light-emitting device 9 are shown below.

[0435] [Chemical Formula 10]

[0436]

[0437] (Method for fabricating light-emitting device 8)

[0438] First, an anode (101) was formed by depositing indium tin oxide (ITSO) containing silicon oxide on a glass substrate by a sputtering method. The thickness of the anode (101) was set to 70 nm, and the electrode area was 4 mm 2 It was made (2mm x 2mm).

[0439] Next, in the pretreatment for forming a light-emitting device on a substrate, the surface of the substrate was washed with water and calcined at 200°C for 1 hour, and then UV ozone treatment was performed for 370 seconds.

[0440] After that, 10 -4 The substrate was moved to a vacuum deposition apparatus with the pressure reduced to approximately Pa, vacuum firing was performed at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, and then the substrate was cooled for about 30 minutes.

[0441] Next, the substrate provided with the anode (101) was fixed to a substrate holder provided in a vacuum deposition apparatus such that the side on which the anode (101) is formed faces downward. Then, N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated: BBABnf) represented by structural formula (i) and NDP-9 (manufactured by Analysis Atelier Corporation, material serial number 1S20170124) were co-deposited to a thickness of 10 nm on the anode (101) using a resistance heating method such that the weight ratio of BBABnf to NDP-9 is 1:0.05, thereby forming a hole injection layer (111).

[0442] Next, a first hole transport layer (112-1) is formed by depositing BBABnf to a thickness of 40 nm on the hole injection layer (111), and then a second hole transport layer (112-2) is formed by depositing 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbazole) (abbreviated: PCzN2), represented by structural formula (ii), to a thickness of 20 nm, thereby forming a hole transport layer (112). In addition, the second hole transport layer (112-2) also functions as an electron blocking layer.

[0443] And 4,6-bis[3-(9H-carbazole-9-yl)phenyl]pyrimidine (abbreviated: 4,6mCzP2Pm) represented by structural formula (xviii), 8-(dibenzothiophen-4-yl)-4-phenyl-2-(9'-phenyl-3,3'-bi-9H-carbazole-9-yl)-[1]benzofuro[3,2-d]pyrimidine (abbreviated: 4Ph-8DBt-2PCCzBfpm) represented by structural formula (xx), and 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (abbreviated: TBRb) represented by structural formula (xii) of 4,6mCzP2Pm vs. 4Ph-8DBt-2PCCzBfpm vs. TBRb A light-emitting layer (113) was formed by co-depositing with a thickness of 40 nm so that the weight ratio was 1.0:0.1:0.01.

[0444] Next, an electron transport layer (114) was formed on the light-emitting layer (113) by co-depositing 2-{4-[9,10-di(naphthalene-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviated as ZADN) represented by structural formula (v) and 8-hydroxyquinolinate lithium (abbreviated as Liq) represented by structural formula (vi) to a thickness of 25 nm such that the weight ratio of ZADN to Liq is 1:1.

[0445] After forming the electron transport layer (114), an electron injection layer (115) was formed by depositing Liq to a thickness of 1 nm. Then, a cathode (102) was formed by depositing aluminum to a thickness of 200 nm. Thus, the light-emitting device 8 of the present embodiment was fabricated.

[0446] (Method for fabricating light-emitting device 9)

[0447] The light-emitting device 9 was manufactured in the same manner as the light-emitting device 8, except that the first hole transport layer (112-1) of the light-emitting device 8 was formed to a thickness of 30 nm and the light-emitting layer (113) was formed without TBRb.

[0448] The structures of light-emitting device 8 and light-emitting device 9 are listed in the table below.

[0449] [Table 22]

[0450]

[0451] *1 Light-emitting device 8: 40nm

[0452] Light-emitting device 9: 30nm

[0453] In addition, 4Ph-8DBt-2PCCzBfpm used in the emissive layer is a material that exhibits thermally activated delayed fluorescence (TADF). In the light-emitting device 8, 4Ph-8DBt-2PCCzBfpm is used as a host material. In the light-emitting device 9, which has a light-emitting mechanism in which energy is transferred to the fluorescent material TBRb, the TADF material 4Ph-8DBt-2PCCzBfpm itself emits light.

[0454] The HOMO level, LUMO level, and electron mobility of the organic compound used in this example are listed in the table below. The electron mobility was measured when the square root of the electric field strength [V / cm] was 600.

[0455] [Table 23]

[0456]

[0457] These light-emitting devices were sealed using glass substrates inside a glove box containing a nitrogen atmosphere to prevent exposure to the atmosphere (a sealing material was applied around the device, and UV treatment and heat treatment at 80°C for 1 hour were performed during sealing). The initial characteristics and reliability of the light-emitting devices were measured. The measurements were also performed at room temperature.

[0458] Figure 70 shows the luminance-current density characteristics of light-emitting device 8 and light-emitting device 9. Figure 71 shows the current efficiency-luminance characteristics. Figure 72 shows the luminance-voltage characteristics. Figure 73 shows the current-voltage characteristics. Figure 74 shows the external quantum efficiency-luminance characteristics. Figure 75 shows the emission spectrum. In Table 24, approximately 1000 cd / m² 2 The main characteristics of light-emitting device 8 and light-emitting device 9 at the luminance of were shown.

[0459] [Table 24]

[0460]

[0461] Looking at FIGS. 70 to 75 and Table 24, it can be seen that light-emitting device 8 and light-emitting device 9 according to one embodiment of the present invention are light-emitting devices with high light-emitting efficiency.

[0462] Fig. 76 is 50 mA / cm 2This is a graph showing the change in brightness with respect to driving time at the current density. As shown in FIG. 76, it was found that the light-emitting device 8 and light-emitting device 9 according to one embodiment of the present invention have a long lifespan when TADF is employed in the host material and the light-emitting material, respectively.

[0463] <Reference Example 1>

[0464] In this reference example, the method for calculating the HOMO level, LUMO level, and electron mobility of the organic compound used in the example is described.

[0465] HOMO levels and LUMO levels can be calculated through cyclic voltammetry (CV) measurements.

[0466] An electrochemical analyzer (ALS Model 600A or 600C, manufactured by BAS Inc.) was used as the measuring device. The solution for CV measurement was prepared by dissolving tetra-n-butylammonium perchlorate (n-Bu4NClO4, manufactured by Tokyo Chemical Industry Co., Ltd., Catalog No. T0836) as the supporting electrolyte in dehydrated dimethylformamide (DMF, manufactured by Sigma-Aldrich Co. LLC., 99.8%, Catalog No. 22705-6) as the solvent at a concentration of 100 mmol / L, and dissolving the measurement target in the solution at a concentration of 2 mmol / L. A platinum electrode (PTE platinum electrode, manufactured by BAS Inc.) was used as the working electrode, another platinum electrode (Pt counter electrode for VC-3 (5 cm), manufactured by BAS Inc.) was used as the auxiliary electrode, and Ag / Ag was used as the reference electrode. +An electrode (RE7 non-aqueous solvent reference electrode, manufactured by BAS Inc.) was used. In addition, measurements were performed at room temperature (20°C to 25°C). Also, the scan rate during CV measurement was fixed at 0.1 V / sec, and the oxidation potential Ea[V] and reduction potential Ec[V] for the reference electrode were measured. Potential Ea is the intermediate potential of the oxidation-reduction wave, and potential Ec is the intermediate potential of the reduction-oxidation wave. Here, since the potential energy of the reference electrode used in this example with respect to the vacuum level is known to be -4.94[eV], the HOMO level and LUMO level can be calculated from the equations HOMO level[eV]=-4.94-Ea and LUMO level[eV]=-4.94-Ec.

[0467] Electron mobility can be measured by the impedance spectroscopy (IS) method.

[0468] Methods for measuring the carrier mobility of EL materials, such as the time-of-flight (TOF) method or the IV characteristics of space-charge-limited current (SCLC), have long been known. The TOF method requires a sample much thicker than that of an actual organic EL device. The SCLC method has the disadvantage, for example, that it cannot obtain the electric field strength dependence of carrier mobility. Since the organic film required for measurements using the IS method is thin (about tens of nm), the organic film can be formed with a relatively small amount of EL material, allowing mobility to be measured at a thickness close to that of an actual EL device. With this method, the electric field strength dependence of carrier mobility can also be measured.

[0469] In the IS method, a small sinusoidal voltage signal (V=V0[exp(jωt)]) is applied to an EL element, and the impedance of the EL element is obtained from the phase difference between the current amplitude of the response current signal (I=I0exp[j(ωt+Φ)]) and the input signal. By applying voltage to the EL element while varying the frequency from a high level to a low level, components with various relaxation times that contribute to the impedance can be separated and measured.

[0470] Here, the admittance Y (=1 / Z), which is the reciprocal of the impedance, can be expressed in terms of conductance G and susceptance B as shown in the following equation (1).

[0471] [Mathematical Formula 1]

[0472]

[0473] In addition, the following equations (2) and (3) can be derived using a single injection model. Here, g in equation (4) is differential conductance. In the equation, C represents capacitance, θ represents the travel angle (ωt), ω represents the angular frequency, and t represents the travel time. For the analysis, the current equation, the Poisson equation, and the current continuity equation are used, and the diffusion current and trap level are ignored.

[0474] [Mathematical Formula 2]

[0475]

[0476] The method for calculating mobility from the frequency characteristics of capacitance is the -△B method. The method for calculating mobility from the frequency characteristics of conductance is the ω△G method.

[0477] In practice, first, an electron-only device is fabricated using a material for which electron mobility is to be calculated. An electron-only device is a device designed to allow only electrons to flow as carriers. In this specification, a method for calculating mobility from the frequency characteristics of capacitance (the -△B method) is described. FIG. 37 is a schematic diagram of the electron-only device used for this measurement.

[0478] As illustrated in FIG. 37, the electron-only device of the present embodiment fabricated for measurement includes a first layer (210), a second layer (211), and a third layer (212) between the anode (201) and the cathode (202). The material for which electron mobility is to be obtained is used as the material for the second layer (211). An example of measuring the electron mobility of a film formed by co-deposition of ZADN and Liq in a weight ratio of 1:1 is described. Specific structural examples are listed in the table below.

[0479] [Table 25]

[0480]

[0481] FIG. 38 shows the current density-voltage characteristics of an electron-only device using a film formed by the co-deposition of ZADN and Liq as the second layer (211).

[0482] Impedance was measured under conditions where the frequency was 1 Hz to 3 MHz, the AC voltage was 70 mV, and the DC voltage was applied within the range of 5.0 V to 9.0 V. Here, capacitance was calculated from the admittance (Equation (1)) which is the reciprocal of the obtained impedance. FIG. 39 shows the frequency characteristics of the calculated capacitance C when the applied voltage is 7.0 V.

[0483] The frequency characteristics of the capacitance C are obtained from the phase difference of the current, which is caused by the fact that the space charge generated by carriers injected by a minute voltage signal cannot completely follow the minute AC voltage. The travel time of the injected carriers within the film is defined as the time T until the carriers reach the opposing electrode, and is represented by the following equation (5).

[0484] [Mathematical Formula 3]

[0485]

[0486] The change in negative susceptance (-△B) corresponds to the value (-ω△C) obtained by multiplying the change in capacitance -△C by the angular frequency ω. According to Equation (3), the peak frequency f' on the lowest frequency side max (=ω max There is a relationship between / 2π) and the driving time T as shown in the following equation (6).

[0487] [Mathematical Formula 4]

[0488]

[0489] FIG. 40 shows the frequency characteristics of -△B calculated from the above measurement (i.e., -△B when the DC voltage is 7.0V). The peak frequency f' on the lowest frequency side. max This is indicated by an arrow in Fig. 40.

[0490] f' obtained from the above measurements and analyses max Since the travel time T is obtained from (see Equation (6) above), in this embodiment, the electron mobility when the DC voltage is 7.0 V can be obtained from Equation (5). By performing the same measurement within the range of DC voltages from 5.0 V to 9.0 V, the electron mobility at each voltage (electric field strength) can be calculated, and thus the dependence of mobility on electric field strength can be measured.

[0491] FIG. 41 shows the final electric field strength dependence of the electron mobility of the organic compound obtained by the above calculation method, and Table 10 shows that the square root of the electric field strength [V / cm] read from the figure is 600 [V / cm] 1 / 2 This represents the value of electron mobility in that case.

[0492] [Table 26]

[0493]

[0494] As described above, electron mobility can be calculated. For details on the measurement method, please refer to T. Okachi et al., Japanese Journal of Applied Physics, vol. 47, No. 12, pp. 8965-8972, 2008.

[0495] <Reference Example 2>

[0496] The synthesis method of the undisclosed substances 9mDBtBPNfpr and 8BP-4mDBtPBfpm used in this embodiment will be described.

[0497] <<Synthesizing Method of 9mDBtBPNfpr>>

[0498] The synthesis method of 9-[(3'-dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated: 9mDBtBPNfpr), represented by structural formula (x) in Example 1, is described. The structure of 9mDBtBPNfpr is shown below.

[0499] [Chemical Formula 11]

[0500]

[0501] (Step 1: Synthesis of 6-chloro-3-(2-methoxynaphthalene-1-yl)pyrazine-2-amine)

[0502] First, 4.37 g of 3-bromo-6-chloropyrazine-2-amine, 4.23 g of 2-methoxynaphthalene-1-boronic acid, 4.14 g of potassium fluoride, and 75 mL of dehydrated tetrahydrofuran were placed in a 3-neck flask equipped with a reflux tube, and the air in the flask was replaced with nitrogen. The mixture in the flask was degassed by stirring under reduced pressure, and then 0.57 g of tris(dibenzylideneacetone)dipalladium (O) (abbreviated: Pd2(dba)3) and 4.5 mL of tri-tert-butylphosphine (abbreviated: P(tBu)3) were added. The mixture was reacted by stirring at 80°C for 54 hours.

[0503] After a predetermined amount of time had elapsed, the obtained mixture was filtered by suction, and the filtrate was concentrated. Then, the mixture was purified by silica gel column chromatography using a developing solvent (toluene:ethyl acetate = 9:1) to obtain the target pyrazine derivative (yellowish-white powder 2.19 g, yield 36%). The synthesis scheme of Step 1 is shown below.

[0504] [Chemical Formula 12]

[0505]

[0506] (Step 2: Synthesis of 9-chloronaphtho[1',2':4,5]furo[2,3-b]pyrazine)

[0507] Next, 2.18 g of 6-chloro-3-(2-methoxynaphthalene-1-yl)pyrazine-2-amine obtained in Step 1, 63 mL of dehydrated tetrahydrofuran, and 84 mL of glacial acetic acid were placed in a three-necked flask, and the air inside the flask was replaced with nitrogen. After cooling the flask to -10°C, 2.8 mL of tert-butyl nitrite was added dropwise, and the mixture was stirred at -10°C for 30 minutes and at 0°C for 3 hours. After the specified time had elapsed, 250 mL of water was added to the resulting suspension and filtered by suction to obtain the target pyrazine derivative (1.48 g of yellowish-white powder, yield 77%). The synthesis scheme for Step 2 is shown below.

[0508] [Chemical Formula 13]

[0509]

[0510] (Step 3: Synthesis of 9-[(3'-Dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated: 9mDBtBPNfpr))

[0511] In a three-necked flask, 1.48 g of 9-chloronaphtho[1',2':4,5]furo[2,3-b]pyrazine obtained in Step 2, 3.41 g of 3'-(4-dibenzothiophen)-1,1'-biphenyl-3-boronic acid, 8.8 mL of 2 M aqueous potassium carbonate solution, 100 mL of toluene, and 10 mL of ethanol were added, and the air in the flask was replaced with nitrogen. The mixture in the flask was degassed by stirring under reduced pressure, and then 0.84 g of bis(triphenylphosphine)palladium(II) dichloride (abbreviated: Pd(PPh3)2Cl2) was added. This mixture was reacted by stirring at 80°C for 18 hours.

[0512] After a predetermined period of time, the obtained suspension was filtered by suction and then washed with water and ethanol. The obtained solid was dissolved in toluene, and the mixture was filtered through a filtration aid in which celite, alumina, and celite were layered in that order. The target substance was then obtained by recrystallization using a mixed solvent of toluene and hexane (pale yellow solid 2.66 g, yield 82%).

[0513] 2.64 g of a pale yellow solid obtained by the train sublimation method was purified by sublimation. The solid was heated at 315°C under sublimation purification conditions with a pressure of 2.6 Pa and an argon flow rate of 15 mL / min. After sublimation purification, 2.34 g of the target pale yellow solid was obtained with a recovery rate of 89%. The synthesis scheme of Step 3 is shown below.

[0514] [Chemical Formula 14]

[0515]

[0516] Nuclear magnetic resonance of the pale yellow solid obtained in Step 3 ( 1 The results of the analysis by H-NMR spectroscopy are shown below. From these results, it was found that 9mDBtBPNfpr was obtained.

[0517] 1H-NMR.δ(CD2Cl2): 7.47-7.51 (m, 2H), 7.60-7.69 (m, 5H), 7.79-7.89 (m, 6H), 8.05 (d, 1H), 8.10-8.11 (m, 2H), 8.18-8.23 (m, 3H), 8.53(s, 1H), 9.16(d, 1H), 9.32(s, 1H).

[0518] <<Synthesizing Method of 8BP-4mDBtPBfpm>>

[0519] The synthesis method of 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated: 8BP-4mDBtPBfpm), represented by structural formula (xiii) in the examples, is described. The structure of 8BP-4mDBtPBfpm is shown below.

[0520] [Chemical Formula 15]

[0521]

[0522] (Synthesis of 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine)

[0523] 1.37 g of 8-chloro-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine, 0.657 g of 4-biphenylboronic acid, 1.91 g of tripotassium phosphate, 30 mL of diglime, and 0.662 g of t-butanol were added to a 3-neck flask. The mixture was degassed by stirring under reduced pressure, and the air in the flask was replaced with nitrogen.

[0524] This mixture was heated at 60°C, 23.3 mg of palladium(II) acetate and 66.4 mg of di(1-adamanthyl)-n-butylphosphine were added, and the mixture was stirred at 120°C for 27 hours. Water was added to the reaction solution, and the mixture was filtered by suction. The resulting residue was washed with water, ethanol, and toluene. The residue was dissolved in heated toluene and then filtered through a filtration aid filled with celite, alumina, and celite in that order. The resulting solution was concentrated and dried, and then recrystallized using toluene to obtain the target white solid at a yield of 1.28 g and a yield of 74%.

[0525] 1.26 g of a white solid was sublimated and purified by the train sublimation method. The solid was heated at 310°C under sublimation purification conditions with a pressure of 2.56 Pa and an argon flow rate of 10 mL / min. After sublimation purification, 1.01 g of the target product, a pale yellow solid, was obtained with a recovery rate of 80%. The synthesis scheme is shown below.

[0526] [Chemical Formula 16]

[0527]

[0528] Nuclear magnetic resonance of the pale yellow solid obtained by the above reaction ( 1 The results of the analysis by H-NMR spectroscopy are shown below. From these results, it was found that 8BP-4mDBtPBfpm was obtained.

[0529] 1 H-NMR.δ(CDCl3): 7.39(t, 1H), 7.47-7.53(m, 4H), 7.63-7.67(m, 2H), 7.68(d, 2H), 7.75(d, 2H), 7.79-7.83(m, 4H), 7.87(d, 1H), 7.98(d, 1H), 8.02(d, 1H), 8.23-8.26(m, 2H), 8.57(s, 1H), 8.73(d, 1H), 9.05(s, 1H), 9.34(s, 1H).

[0530] <<Synthesizing Method of 4Ph-8DBt-2PCCzBfpm>>

[0531] The synthesis method of 8-(dibenzothiophen-4-yl)-4-phenyl-2-(9'-phenyl-3,3'-bi-9H-carbazole-9-yl)-[1]benzofuro[3,2-d]pyrimidine (abbreviated: 4Ph-8DBt-2PCCzBfpm), represented by structural formula (xix) in the examples, is described. The structure of 4Ph-8DBt-2PCCzBfpm is shown below.

[0532] [Chemical Formula 17]

[0533]

[0534] (Step 1; Synthesis of 2,8-dichloro-4-phenyl-[1]benzofuro[3,2-d]pyrimidine)

[0535] 10 g (37 mmol) of 2,4,8-trichloro-[1]benzofuro[3,2-d]pyrimidine, 4.5 g (371 mmol) of phenylboronic acid, 37 mL of 2 M aqueous potassium carbonate solution, 180 mL of toluene, and 18 mL of ethanol were added to a 500 mL three-necked flask. The mixture in the flask was degassed, and the air in the flask was replaced with nitrogen. 1.3 g (1.8 mmol) of bis(triphenylphosphine)palladium(II) dichloride was added to this mixture, and the mixture was then stirred at 80°C for 16 hours.

[0536] After a predetermined time had elapsed, the obtained reaction mixture was concentrated, water was added, and the mixture was subjected to suction filtration. The resulting residue was washed with ethanol to obtain a solid. This solid was dissolved in toluene and subsequently subjected to suction filtration through a filter medium in which celite, alumina, and celite were layered in that order. The resulting filtrate was concentrated to obtain 11 g of the target white solid with a yield of 91%. The synthesis scheme of Step 1 is shown below.

[0537] [Chemical Formula 18]

[0538]

[0539] (Step 2; Synthesis of 8-chloro-4-phenyl-2-(9'-phenyl-3,3'-bi-9H-carbazole-9-yl)-[1]benzofuro[3,2-d]pyrimidine)

[0540] In a 300 mL three-necked flask, 5.0 g (16 mmol) of 2,8-dichloro-4-phenyl-[1]benzofuro[3,2-d]pyrimidine obtained in Step 1, 6.5 g (16 mmol) of 9-phenyl-3,3'-bi-9H-carbazole, 3.1 g (32 mmol) of tert-sodium butoxide, and 150 mL of xylene were added, and the air in the flask was replaced with nitrogen. Then, 224 mg (0.64 mmol) of di-tert-butyl(1-methyl-2,2-diphenylcyclopropyl)phosphine (abbreviated as cBRIDP) and 58 mg (0.16 mmol) of allylpalladium(II) chloride dimer were added, and the mixture was heated and stirred at 90°C for 7 hours.

[0541] Water was added to the obtained reaction mixture, and extraction with toluene was performed on the aqueous layer. The obtained extract solution and the organic layer were combined and washed with saturated saline solution, and anhydrous magnesium sulfate was added to the organic layer to dry it. The obtained mixture was naturally filtered, and the filtrate was concentrated to obtain a solid. This solid was purified by silica gel column chromatography. As the developing solvent, a mixed solvent containing toluene and hexane in a 1:1 ratio was used. The obtained fraction was concentrated to obtain 5.5 g of the target yellow solid with a yield of 50%. The synthesis scheme for Step 2 is shown below.

[0542] [Chemical Formula 19]

[0543]

[0544] (Step 3: Synthesis of 4Ph-8DBt-2PCCzBfpm)

[0545] 2.25 g (3.3 mmol) of 8-chloro-4-phenyl-2-(9'-phenyl-3,3'-bi-9H-carbazole-9-yl)[1]benzofuro[3,2-d]pyrimidine obtained in step 2, 0.82 g (3.6 mmol) of 4-dibenzothiophenboronic acid, 1.5 g (9.8 mmol) of cesium fluoride, and 35 mL of xylene were added to a 3-neck flask, and the air in the flask was replaced with nitrogen.

[0546] The temperature of this mixture was raised to 60°C, 60 mg (0.065 mmol) of tris(dibenzylideneacetone)dipalladium (0) and 77 mg (0.2 mmol) of 2'-(dicyclohexylphosphino)acetophenoneethyleneketal were added, and the mixture was heated and stirred at 100°C for 16 hours. Additionally, 30 mg (0.032 mmol) of tris(dibenzylideneacetone)dipalladium (0) and 36 mg (0.1 mmol) of 2'-(dicyclohexylphosphino)acetophenoneethyleneketal were added to this mixture, and the mixture was heated and stirred at 110°C for 7 hours and at 120°C for 7 hours.

[0547] Water was added to the obtained reaction mixture, the mixture was subjected to suction filtration, and the residue was washed with ethanol. This solid was dissolved in toluene and subsequently subjected to suction filtration through a filter medium in which celite, alumina, and celite were layered in that order. The resulting filtrate was concentrated and recrystallized using toluene to obtain the target yellow solid at a yield of 1.87 g and a yield of 68%. The synthesis scheme is shown below.

[0548] [Chemical Formula 20]

[0549]

[0550] 0.90 g of the yellow solid obtained by the train sublimation method was purified by sublimation. The pressure was 1.58 x 10⁻¹⁰ -2 The solid was heated under sublimation purification conditions with Pa and a heating temperature of 400℃. After sublimation purification, 0.78g of the target yellow solid was obtained with a recovery rate of 86%.

[0551] Nuclear magnetic resonance of the yellow solid obtained from the above reaction ( 1 The results of the analysis by H-NMR spectroscopy are shown below. From these results, it was found that 4Ph-8DBt-2PCCzBfpm was obtained.

[0552] 1 H-NMR.δ(CDCl3): 7.33(t, 1H), 7.41-7.53(m, 7H), 7.59(t, 1H), 7.62-7.70(m, 7H), 7.72-7.75(m, 2H), 7.83(dd, 1H), 7.87(dd, 1H), 7.93-7.95(m, 2H), 8.17(dd, 1H), 8.23-8.26(m, 4H), 8.44(d, 1H), 8.52(d, 1H), 8.75(d, 1H), 8.2(d, 2H), 9.02(d, 1H), 9.07(d, 1H). Explanation of the symbols

[0553] 101: Anode, 102: Cathode, 103: EL layer, 111: Hole injection layer, 112: Hole transport layer, 112-1: First hole transport layer, 112-2: Second hole transport layer, 113: Emitting layer, 113-1: Emitting region, 114: Electron transport layer, 114-1: Non-radiative recombination region, 115: Electron injection layer, 116: Charge generation layer, 117: p-type layer, 118: Electron relay layer, 119: Electron injection buffer layer, 201: Anode, 202: Cathode, 210: First layer, 211: Second layer, 212: Third layer, 400: Substrate, 401: Anode, 403: EL layer, 404: Cathode, 405: Sealing material, 406: Sealing material, 407: Sealing substrate, 412: Pad, 420: IC chip, 501: Anode, 502: Cathode, 511: First light-emitting unit, 512: Second light-emitting unit, 513: Charge generation layer, 601: Driving circuit section (source line driving circuit), 602: Pixel section, 603: Driving circuit section (gate line driving circuit), 604: Sealing substrate, 605: Sealing material, 607: Space, 608: Wiring, 609: FPC (flexible printed circuit), 610: Device substrate, 611: Switching FET, 612: Current control FET, 613: Anode, 614: Insulator, 616: EL layer, 617: Cathode, 618: Light-emitting device, 951: Substrate, 952: Electrode, 953: Insulating layer, 954: Barrier layer, 955: EL layer, 956: Electrode, 1001: Substrate, 1002: Base insulating film, 1003: Gate insulating film, 1006: Gate electrode, 1007: Gate electrode, 1008: Gate electrode, 1020: First interlayer insulating film, 1021: Second interlayer insulating film, 1022: Electrode, 1024W: Anode, 1024R: Anode, 1024G: Anode, 1024B: Anode, 1025: Barrier, 1028: EL layer, 1029: Cathode, 1031: Sealing substrate, 1032: Sealing material, 1033: Transparent substrate, 1034R: Red colored layer,1034G: Green coloring layer, 1034B: Blue coloring layer, 1035: Black matrix, 1036: Overcoat layer, 1037: Third interlayer insulating film, 1040: Pixel section, 1041: Driving circuit section, 1042: Peripheral section, 2001: Housing, 2002: Light source, 2100: Robot, 2110: Computing unit, 2101: Illumination sensor, 2102: Microphone, 2103: Upper camera, 2104: Speaker, 2105: Display, 2106: Lower camera, 2107: Obstacle sensor, 2108: Moving mechanism, 3001: Lighting device, 5000: Housing, 5001: Display section, 5002: Display section, 5003: Speaker, 5004: LED lamp, 5006: Connection terminal, 5007: Sensor, 5008: Microphone, 5012: Support part, 5013: Earphone, 5100: Robot vacuum cleaner, 5101: Display, 5102: Camera, 5103: Brush, 5104: Operation button, 5150: Foldable portable information terminal, 5151: Housing, 5152: Display area, 5153: Curved part, 5120: Dust, 5200: Display area, 5201: Display area, 5202: Display area, 5203: Display area, 7101: Housing, 7103: Display unit, 7105: Stand, 7107: Display unit, 7109: Operation key, 7110: Remote controller, 7201: Main body, 7202: Housing, 7203: Display unit, 7204: Keyboard, 7205: External connection port, 7206: Pointing device, 7210: Second display unit, 7401: Housing, 7402: Display unit, 7403: Operation button, 7404: External connection port, 7405: Speaker, 7406: Microphone, 9310: Foldable portable information terminal, 9311: Display panel, 9313: Hinge, 9315: Housing., The present application is based on Japanese patent application No. 2018-191681 filed with the Japan Patent Office on October 10, 2018; Japanese patent application No. 2018-191678 filed with the Japan Patent Office on October 10, 2018; Japanese patent application No. 2018-191887 filed with the Japan Patent Office on October 10, 2018; Japanese patent application No. 2018-225260 filed with the Japan Patent Office on November 30, 2018; Japanese patent application No. 2019-020057 filed with the Japan Patent Office on February 6, 2019; and Japanese patent application No. 2019-087060 filed with the Japan Patent Office on April 30, 2019. The full text is incorporated into the specification as a reference.

Claims

Claim 1 As a light-emitting device, a positive electrode; a negative electrode; and includes an EL layer between the anode and the cathode, wherein the EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side, wherein the first layer is in contact with the anode and the fourth layer is in contact with the light-emitting layer, wherein the first layer comprises a first organic compound and a second organic compound, wherein the second layer comprises a third organic compound, wherein the third layer comprises a fourth organic compound, wherein the light-emitting layer comprises a fifth organic compound and a sixth organic compound, wherein the fourth layer comprises a seventh organic compound and an eighth substance, wherein the first organic compound comprises at least one of a cyano group and a halogen group, wherein the fifth organic compound is a light-emitting central substance, wherein the HOMO level of the second organic compound is between -5.7 eV and -5.4 eV, wherein the eighth substance is an organic complex of an alkali metal or an alkaline earth metal, and the HOMO of the seventh organic compound A light-emitting device with a level of -6.0 eV or higher. Claim 2 As a light-emitting device, a positive electrode; a negative electrode; and includes an EL layer between the anode and the cathode, wherein the EL layer comprises a first layer, a second layer, a third layer, a light-emitting layer, and a fourth layer in that order from the anode side, wherein the first layer is in contact with the anode and the fourth layer is in contact with the light-emitting layer, wherein the first layer comprises a first organic compound and a second organic compound, wherein the second layer comprises a third organic compound, wherein the third layer comprises a fourth organic compound, wherein the light-emitting layer comprises a fifth organic compound and a sixth organic compound, wherein the fourth layer comprises a seventh organic compound and an eighth material, wherein the first organic compound comprises at least one of a cyano group and a halogen group, wherein the second organic compound comprises a first hole-transporting framework, wherein the third organic compound comprises a second hole-transporting framework, wherein the fourth organic compound comprises a third hole-transporting framework, wherein the fifth organic compound is a light-emitting central material, and wherein the A light-emitting device, wherein the HOMO level of the 2 organic compound is -5.7 eV or higher and -5.4 eV or lower, the first hole-transporting backbone, the second hole-transporting backbone, and the third hole-transporting backbone are each independently one of the carbazole backbone, the dibenzofuran backbone, the dibenzothiophen backbone, and the anthracene backbone, the 8th material is an organic complex of an alkali metal or alkaline earth metal, and the HOMO level of the 7th organic compound is -6.0 eV or higher. Claim 3 A light-emitting device according to claim 1 or 2, wherein the seventh organic compound comprises an anthracene backbone. Claim 4 A light-emitting device according to claim 1 or 2, wherein the difference between the HOMO level of the second organic compound and the HOMO level of the third organic compound is 0.2 eV or less, and the HOMO level of the third organic compound is equal to or deeper than the HOMO level of the second organic compound. Claim 5 A light-emitting device according to claim 1 or 2, wherein the halogen group is a fluoro group. Claim 6 A light-emitting device according to claim 1 or 2, wherein a degradation curve representing a change in luminance of light obtained when a constant current is supplied to the light-emitting device has a maximum value. Claim 7 In claim 6, the above degradation curve is a light-emitting device having a portion where the brightness exceeds 100%. Claim 8 A light-emitting device according to claim 1 or 2, wherein the seventh organic compound comprises an anthracene backbone and a heterocyclic backbone. Claim 9 A light-emitting device according to claim 1 or 2, wherein the electron mobility of the seventh organic compound is lower than the electron mobility of the sixth organic compound. Claim 10 A light-emitting device according to claim 1 or 2, wherein the difference between the HOMO level of the third organic compound and the HOMO level of the fourth organic compound is 0.2 eV or less. Claim 11 A light-emitting device according to claim 1 or 2, wherein the HOMO level of the fourth organic compound is equal to or deeper than the HOMO level of the third organic compound. Claim 12 A light-emitting device according to claim 1 or 2, wherein the second organic compound comprises a dibenzofuran backbone. Claim 13 A light-emitting device according to claim 1 or 2, wherein the second organic compound and the third organic compound are the same material. Claim 14 A light-emitting device according to claim 1 or 2, wherein the fifth organic compound is a blue fluorescent material. Claim 15 An electronic device comprising: a light-emitting device according to claim 1 or 2; and at least one of a sensor, an operating button, a speaker, and a microphone. Claim 16 A lighting device comprising a light-emitting device according to claim 1 or 2, and a housing.

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