Light-emitting device and display device

Abstract

A light-emitting device with advantageous properties is provided. The light-emitting device comprises a first electrode, a second electrode, an intermediate layer therebetween, a first light-emitting layer, a second light-emitting layer, a first electron-transport layer, and a second electron-transport layer. The first light-emitting layer is located between the first electrode and the intermediate layer. The second light-emitting layer is located between the intermediate layer and the second electrode. The first electron-transport layer is located between the first light-emitting layer and the intermediate layer. The second electron-transport layer is located between the second light-emitting layer and the second electrode. The second electron-transport layer has a multilayer structure.The intermediate layer contains a second organic compound having a phenanthroline framework. The first light-emitting layer and the second light-emitting layer contain the same emission center substance. The first light-emitting layer and the second light-emitting layer are separated by a light-emitting layer of at least one of a plurality of adjacent light-emitting devices.

Description

Background of the invention 1. Field of the invention

[0001] An embodiment of the present invention relates to an organic compound, an organic semiconductor element, a light-emitting device, a photodiode sensor, a display module, a lighting module, a display device, an electronic device, a lighting device, and an electronic device. Note that an embodiment of the present invention is not limited to the above technical field. The technical field of an embodiment of the invention disclosed in this specification and the like relates to an article, a method, or a manufacturing method. An embodiment of the present invention relates to a process, a machine, a product, or a composition.In particular, examples of the technical field of an embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a lighting device, a power storage device, a memory device, an imaging device, an operation method thereof, and a manufacturing method thereof. 2. Description of the state of the art

[0002] Light-emitting devices (also called organic EL elements) containing organic compounds and utilizing electroluminescence (EL) are widely used in practice. The basic structure of such light-emitting devices consists of an organic compound layer containing an emitting center substance sandwiched between a pair of electrodes. Charge carriers are injected by applying a voltage to the device, and the recombination energy of the charge carriers is utilized, resulting in light emission from the emitting center substance.

[0003] Because such light-emitting devices are self-luminous, display devices using the light-emitting devices for pixels have higher visibility than liquid crystal display devices and do not require backlighting. Display devices incorporating such light-emitting devices are also very advantageous in that they can be thin and lightweight. Another feature of such light-emitting devices is their very fast response speed.

[0004] Since the light-emitting layers of such light-emitting devices can be formed as continuous planar layers, planar light emission can be achieved. This feature is difficult to achieve with point light sources, typically incandescent lamps and LEDs, or linear light sources, typically fluorescent lamps; therefore, the light-emitting devices also have great potential as planar light sources that can be used for lighting devices and the like.

[0005] As described above, display devices or lighting devices including light-emitting devices are suitable for various electronic devices, and research and development of light-emitting devices have progressed for better characteristics.

[0006] Tandem light-emitting devices have attracted particular attention due to their high power efficiency, and Patent Documents 1 and 2 disclose tandem light-emitting devices fabricated by a side-by-side patterning method. [Reference] [Patent Document 1] Japanese Patent Laid-Open No. 2005-317548 [Patent Document 2] Japanese Patent Laid-Open No. 2023-161850 Summary of the invention

[0007] An object of an embodiment of the present invention is to provide a light-emitting device with advantageous properties. Another object of an embodiment of the present invention is to provide a light-emitting device with high emission efficiency. Another object of an embodiment of the present invention is to provide a light-emitting device with high reliability. Another object of an embodiment of the present invention is to provide a light-emitting device with low operating voltage. Another object of an embodiment of the present invention is to provide a light-emitting device with high reliability and low operating voltage.

[0008] Another object of an embodiment of the present invention is to provide a light-emitting device that enables a display device to have advantageous characteristics. Another object of an embodiment of the present invention is to provide a light-emitting device that enables a display device to have high emission efficiency. Another object of an embodiment of the present invention is to provide a light-emitting device that enables a display device to have high reliability. Another object of an embodiment of the present invention is to provide a display device that enables a display device to have a low operating voltage.Another object of an embodiment of the present invention is to provide a light-emitting device that enables a display device to have high reliability and low operating voltage.

[0009] Another object of an embodiment of the present invention is to provide an organic semiconductor device, a light-emitting device, a light-receiving device, a display device, an electronic device, or a lighting device, each having low power consumption. Another object of an embodiment of the present invention is to provide a high-reliability electronic device or a lighting device. Another object of an embodiment of the present invention is to provide a novel organic semiconductor device, a novel light-emitting device, a novel light-receiving device, a novel display device, a novel electronic device, or a novel lighting device.

[0010] In the present invention, it is only necessary that at least one of the objects described above be achieved. It should be noted that the description of these objects does not preclude the existence of other objects. In one embodiment of the present invention, it is unnecessary to achieve all of these objects. Other objects will become apparent from and can be derived from the explanation of the description, the drawings, the claims, and the like.

[0011] One embodiment of the present invention is a light-emitting device comprising a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron-transport layer, and a second electron-transport layer. The intermediate layer is located between the first electrode and the second electrode. The first light-emitting layer is located between the first electrode and the intermediate layer. The second light-emitting layer is located between the intermediate layer and the second electrode. The first electron-transport layer is located between the first light-emitting layer and the intermediate layer. The second electron-transport layer is located between the second light-emitting layer and the second electrode.The second electron-transport layer has a multilayer structure of at least a third electron-transport layer and a fourth electron-transport layer. The fourth electron-transport layer is located between the third electron-transport layer and the second electrode. The intermediate layer comprises a mixed layer of a second organic compound and lithium or a lithium compound, and the second organic compound has a phenanthroline skeleton. The first light-emitting layer contains a first emission center substance. The second light-emitting layer contains a second emission center substance. A difference between a maximum peak wavelength of an emission spectrum of the first emission center substance and a maximum peak wavelength of an emission spectrum of the second emission center substance is less than or equal to 30 nm.The first light-emitting layer and the second light-emitting layer are light-emitting layers different from a light-emitting layer of at least one of a plurality of light-emitting devices adjacent to the light-emitting device.

[0012] Another embodiment of the present invention is a light-emitting device comprising a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron-transport layer, and a second electron-transport layer. The intermediate layer is located between the first electrode and the second electrode. The first light-emitting layer is located between the first electrode and the intermediate layer. The second light-emitting layer is located between the intermediate layer and the second electrode. The first electron-transport layer is located between the first light-emitting layer and the intermediate layer. The second electron-transport layer is located between the second light-emitting layer and the second electrode.The second electron-transport layer has a multilayer structure composed of at least a third electron-transport layer and a fourth electron-transport layer. The fourth electron-transport layer is located between the third electron-transport layer and the second electrode. The fourth electron-transport layer contains a first organic compound having a triazine skeleton. The intermediate layer comprises a mixed layer of a second organic compound and lithium or a lithium compound, and the second organic compound has a phenanthroline skeleton. The first light-emitting layer contains a first emission center substance. The second light-emitting layer contains a second emission center substance.A difference between a maximum peak wavelength of an emission spectrum of the first emission center substance and a maximum peak wavelength of an emission spectrum of the second emission center substance is less than or equal to 30 nm. The first light-emitting layer and the second light-emitting layer are light-emitting layers different from a light-emitting layer of at least one of a plurality of light-emitting devices adjacent to the light-emitting device.

[0013] Another embodiment of the present invention is a light-emitting device comprising a first electrode, a second electrode, an intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron-transport layer, and a second electron-transport layer. The intermediate layer is located between the first electrode and the second electrode. The first light-emitting layer is located between the first electrode and the intermediate layer. The second light-emitting layer is located between the intermediate layer and the second electrode. The first electron-transport layer is located between the first light-emitting layer and the intermediate layer. The second electron-transport layer is located between the second light-emitting layer and the second electrode.The second electron-transport layer has a multilayer structure consisting of at least a third electron-transport layer and a fourth electron-transport layer. The fourth electron-transport layer is located between the third electron-transport layer and the second electrode. The fourth electron-transport layer contains a first organic compound having a triazine skeleton. The first electron-transport layer contains a third organic compound having a triazine skeleton. The intermediate layer contains a second organic compound having a phenanthroline skeleton. The first light-emitting layer contains a first emission center substance. The second light-emitting layer contains a second emission center substance.A difference between a maximum peak wavelength of an emission spectrum of the first emission center substance and a maximum peak wavelength of an emission spectrum of the second emission center substance is less than or equal to 30 nm. The first light-emitting layer and the second light-emitting layer are light-emitting layers different from a light-emitting layer of at least one of a plurality of light-emitting devices adjacent to the light-emitting device.

[0014] In the light-emitting device having the above structure, the intermediate layer contains lithium or a lithium compound.

[0015] In the light-emitting device having the above structure, the intermediate layer comprises a mixed layer of the second organic compound and the lithium or the lithium compound.

[0016] In any of the light-emitting devices having the above structures, the fourth electron transport layer contains lithium or a lithium compound.

[0017] In any of the light-emitting devices having the above structures, the first emission center substance is the same substance as the second emission center substance.

[0018] In any of the light-emitting devices having the above structures, the intermediate layer comprises a first layer containing the second organic compound.

[0019] In the light-emitting device having the above structure, the intermediate layer further comprises a second layer, and the second layer is located between the first layer and the second light-emitting layer.

[0020] In the light-emitting device having the above structure, the second layer contains a fourth organic compound having a hole transport property.

[0021] In the light-emitting device having the above structure, the second layer contains a halogen.

[0022] In the light-emitting device having the above structure, the second layer contains an organic compound having a halogen group and / or a cyano group.

[0023] In the light-emitting device having the above structure, the second layer contains an organic compound having fluorine and / or a cyano group.

[0024] In the light-emitting device having the above structure, the second layer contains an organic compound having at least four halogen groups, at least four cyano groups, or a combination of halogen and cyano groups, the number of which is four or more.

[0025] In the light-emitting device having the above structure, the second layer contains an organic compound having at least four fluorine groups, at least four cyano groups, or a combination of fluorine and cyano groups, the number of which is four or more.

[0026] In any of the light-emitting devices having the above structures, the first electron-transport layer has a multilayer structure of at least a fifth electron-transport layer and a sixth electron-transport layer, and the sixth electron-transport layer is positioned between the fifth electron-transport layer and the intermediate layer.

[0027] In the light-emitting device having the above structure, the sixth electron transport layer contains a third organic compound having a triazine skeleton.

[0028] In the light-emitting device having the above structure, the first organic compound is the same organic compound as the third organic compound.

[0029] Another embodiment of the present invention is a display device comprising any of the above light-emitting devices.

[0030] Another embodiment of the present invention is a display device comprising a first light-emitting device and a second light-emitting device. The first light-emitting device is adjacent to the second light-emitting device. The first light-emitting device comprises a first electrode, a second electrode, a first intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron-transport layer, and a second electron-transport layer. The first intermediate layer is located between the first electrode and the second electrode. The first light-emitting layer is located between the first electrode and the first intermediate layer. The second light-emitting layer is located between the first intermediate layer and the second electrode.The first electron-transport layer is located between the first light-emitting layer and the first intermediate layer. The second electron-transport layer is located between the second light-emitting layer and the second electrode. The second electron-transport layer has a multilayer structure composed of at least a third electron-transport layer and a fourth electron-transport layer. The fourth electron-transport layer is located between the third electron-transport layer and the second electrode. The second light-emitting device comprises a third electrode, a fourth electrode, a second intermediate layer, a third light-emitting layer, a fourth light-emitting layer, a fifth electron-transport layer, and a sixth electron-transport layer. The second intermediate layer is located between the third electrode and the fourth electrode.The third light-emitting layer is located between the third electrode and the second intermediate layer. The fourth light-emitting layer is located between the second intermediate layer and the fourth electrode. The fifth electron-transport layer is located between the third light-emitting layer and the second intermediate layer. The sixth electron-transport layer is located between the fourth light-emitting layer and the fourth electrode. The sixth electron-transport layer has a multilayer structure consisting of at least a seventh electron-transport layer and an eighth electron-transport layer. The eighth electron-transport layer is located between the seventh electron-transport layer and the fourth electrode. The fourth electron-transport layer and the eighth electron-transport layer are formed of the same material.The first intermediate layer and the second intermediate layer each contain a second organic compound and lithium or a lithium compound, and the second organic compound has a phenanthroline skeleton. The first light-emitting layer contains a first emission center substance. The second light-emitting layer contains a second emission center substance. The third light-emitting layer contains a third emission center substance. The fourth light-emitting layer contains a fourth emission center substance. A difference between a maximum peak wavelength of an emission spectrum of the first emission center substance and a maximum peak wavelength of an emission spectrum of the second emission center substance is less than or equal to 30 nm.A difference between a maximum peak wavelength of an emission spectrum of the third emission center substance and a maximum peak wavelength of an emission spectrum of the fourth emission center substance is less than or equal to 30 nm. The first light-emitting layer is a light-emitting layer different from the third light-emitting layer. The second light-emitting layer is a light-emitting layer different from the fourth light-emitting layer.

[0031] Another embodiment of the present invention is a display device comprising a first light-emitting device and a second light-emitting device. The first light-emitting device is adjacent to the second light-emitting device. The first light-emitting device comprises a first electrode, a second electrode, a first intermediate layer, a first light-emitting layer, a second light-emitting layer, a first electron-transport layer, and a second electron-transport layer. The first intermediate layer is located between the first electrode and the second electrode. The first light-emitting layer is located between the first electrode and the first intermediate layer. The second light-emitting layer is located between the first intermediate layer and the second electrode.The first electron-transport layer is located between the first light-emitting layer and the first intermediate layer. The second electron-transport layer is located between the second light-emitting layer and the second electrode. The second electron-transport layer has a multilayer structure composed of at least a third electron-transport layer and a fourth electron-transport layer. The fourth electron-transport layer is located between the third electron-transport layer and the second electrode. The second light-emitting device comprises a third electrode, a fourth electrode, a second intermediate layer, a third light-emitting layer, a fourth light-emitting layer, a fifth electron-transport layer, and a sixth electron-transport layer. The second intermediate layer is located between the third electrode and the fourth electrode.The third light-emitting layer is located between the third electrode and the second intermediate layer. The fourth light-emitting layer is located between the second intermediate layer and the fourth electrode. The fifth electron-transport layer is located between the third light-emitting layer and the second intermediate layer. The sixth electron-transport layer is located between the fourth light-emitting layer and the fourth electrode. The sixth electron-transport layer has a multilayer structure composed of at least a seventh electron-transport layer and an eighth electron-transport layer. The eighth electron-transport layer is located between the seventh electron-transport layer and the fourth electrode. The second electron-transport layer and the sixth electron-transport layer are one continuous layer.The first intermediate layer and the second intermediate layer each contain a second organic compound and lithium or a lithium compound, and the second organic compound has a phenanthroline skeleton. The first light-emitting layer contains a first emission center substance. The second light-emitting layer contains a second emission center substance. The third light-emitting layer contains a third emission center substance. The fourth light-emitting layer contains a fourth emission center substance. A difference between a maximum peak wavelength of an emission spectrum of the first emission center substance and a maximum peak wavelength of an emission spectrum of the second emission center substance is less than or equal to 30 nm.A difference between a maximum peak wavelength of an emission spectrum of the third emission center substance and a maximum peak wavelength of an emission spectrum of the fourth emission center substance is less than or equal to 30 nm. The first light-emitting layer is a light-emitting layer different from the third light-emitting layer. The second light-emitting layer is a light-emitting layer different from the fourth light-emitting layer.

[0032] Another embodiment of the present invention is an electronic device comprising any of the above light-emitting devices and a sensor, a control button, a speaker, or a microphone.

[0033] Another embodiment of the present invention is a lighting device comprising any of the above light-emitting devices and a housing.

[0034] Embodiments of the present invention are not limited to the above embodiments.

[0035] One embodiment of the present invention can provide a light-emitting device with advantageous properties. Another embodiment of the present invention can provide a light-emitting device with high emission efficiency. Another embodiment of the present invention can provide a light-emitting device with high reliability. Another embodiment of the present invention can provide a light-emitting device with low operating voltage. Another embodiment of the present invention can provide a light-emitting device with high reliability and low operating voltage.

[0036] Another embodiment of the present invention can provide a light-emitting device that enables a display device to have advantageous characteristics. Another embodiment of the present invention can provide a light-emitting device that enables a display device to have high emission efficiency. Another embodiment of the present invention can provide a light-emitting device that enables a display device to have high reliability. Another object of an embodiment of the present invention can provide a light-emitting device that enables a display device to have a low operating voltage.Another embodiment of the present invention can provide a light-emitting device that enables a display device to have high reliability and low operating voltage.

[0037] Another embodiment of the present invention may provide an organic semiconductor device, a light-emitting device, a light-receiving device, a display device, an electronic device, or a lighting device, each having low power consumption. Another embodiment of the present invention may provide a high-reliability electronic device or a high-reliability lighting device. Short description of the drawings Fig. 1A and Fig. 1B are schematic representations of light-emitting devices of an embodiment of the present invention. Fig. 2 is a schematic diagram of light-emitting devices of an embodiment of the present invention. Fig. 3 is a schematic diagram of light-emitting devices of an embodiment of the present invention. Fig. 4 is a schematic diagram of light-emitting devices of an embodiment of the present invention. Fig. 5A and Fig. 5B illustrate a display device of an embodiment of the present invention. Fig. 6A and Fig. 6B illustrate a display device of an embodiment of the present invention. Fig. 7A to Fig. 7E are cross-sectional views illustrating an example of a method for manufacturing the display device. Fig. 8A and Fig. 8B are cross-sectional views illustrating the example of the method for manufacturing the display device. Fig. 9A to Fig. 9D are cross-sectional views illustrating the example of the method for manufacturing the display device. Fig. 10A to Fig. 10C are cross-sectional views illustrating the example of the method for manufacturing the display device. Fig. 11A to Fig. 11C are cross-sectional views illustrating the example of the method for manufacturing the display device. Fig. 12A to Fig. 12C are cross-sectional views illustrating the example of the method for manufacturing the display device. Fig. 13A and Fig. 13B are perspective views illustrating a structural example of a display module. Fig. 14A and Fig. 14B are cross-sectional views illustrating structural examples of display devices. Fig. 15 is a perspective view showing a structural example of a display device. Fig. 16 is a cross-sectional view showing a structural example of a display device. Fig. 17 is a cross-sectional view showing a structural example of a display device. Fig. 18A to Fig. 18C illustrates a structural example of a display device. Fig. 19 is a cross-sectional view showing a structural example of a display device. Fig. 20A to Fig. 20C illustrates a structural example of a display device. Fig. 21A to Fig. 21D show examples of portable devices. Fig. 22A to Fig. 22F are examples of electronic devices. Fig. 23A to Fig. 23G are examples of electronic devices. Fig. 24 shows the current density-voltage characteristics of a light-emitting device R1 and a comparative light-emitting device R1. Fig. 25 shows the current efficiency-luminance characteristics of the light-emitting device R1 and the comparative light-emitting device R1. Fig. 26 shows the power efficiency-luminance characteristics of the light-emitting device R1 and the comparative light-emitting device R1. Fig. Figure 27 shows the electroluminescence spectra of the light-emitting device R1 and the comparative light-emitting device R1. Fig. 28 shows the current density-voltage characteristics of a light-emitting device G1 and a comparative light-emitting device G1. Fig. 29 shows the power efficiency-luminance characteristics of the light-emitting device G1 and the comparative light-emitting device G1. Fig. 30 shows the power efficiency-luminance characteristics of the light-emitting device G1 and the comparative light-emitting device G1. Fig. 31 shows the electroluminescence spectra of the light-emitting device G3 and the comparative light-emitting device G1. Fig. 32 shows the current density-voltage characteristics of a light-emitting device B1 and a comparative light-emitting device B1. Fig. 33 shows the power efficiency-luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1. Fig. 34 shows the blue index luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1. Fig. 35 shows the power efficiency-luminance characteristics of the light-emitting device B1 and the comparative light-emitting device B1. Fig. 36 shows the electroluminescence spectra of the light-emitting device B1 and the comparative light-emitting device B1. Detailed description of the invention

[0038] Embodiments of the present invention will be described in detail below with reference to the drawings. It should be noted that the present invention is not limited to the following description, and it will be readily apparent to those skilled in the art that modes and details of the present invention can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as limited to the description of the following embodiments.

[0039] In this specification and the like, a device fabricated using a metal mask or a fine metal mask (FMM) is sometimes referred to as a device having a metal mask (MM) structure. In this specification and the like, a device fabricated without using a metal mask or an FMM is sometimes referred to as a device having a metal maskless (MML) structure. (Embodiment 1)

[0040] A tandem light-emitting device has a structure in which a plurality of light-emitting units are stacked between a pair of electrodes with an intermediate layer (a charge generation layer) therebetween. The plurality of light-emitting units includes their respective light-emitting layers, and each of the light-emitting layers can emit light with a current flowing therethrough. The tandem light-emitting device having such a structure has much higher current efficiency than a light-emitting device other than a tandem device, and can therefore be suitably used for a display device requiring high-luminance display or high reliability.

[0041] Since the tandem light-emitting device comprises a plurality of light-emitting layers and can therefore easily provide white light emission, many full-color display devices incorporating the tandem light-emitting device employ a "white + color filter" method. A color conversion method is also being used in practice, in which light-emitting layers that emit blue light are stacked and a color conversion layer, typically quantum dots, is used.

[0042] Meanwhile, some full-color display devices using a side-by-side (SBS) patterning method and a tandem light-emitting device are also being put into practice. A light-emitting device fabricated by the side-by-side patterning method has little or no energy loss due to a color filter or color conversion layer, and can therefore exhibit higher emission efficiency than light-emitting devices fabricated by the two methods described above.

[0043] In a tandem light-emitting device of one embodiment of the present invention, an electron transport layer included in a light-emitting unit on the cathode side has a multilayer structure, and an intermediate layer contains a second organic compound having a phenanthroline skeleton.

[0044] A light-emitting layer included in the tandem light-emitting device is preferably separate from a light-emitting layer included in at least one adjacent light-emitting device. Alternatively, the light-emitting layer included in the tandem light-emitting device is preferably a light-emitting layer different from a light-emitting layer included in at least one adjacent light-emitting device. Alternatively, the emission color of the tandem light-emitting device or of a pixel comprising the tandem light-emitting device is preferably different from the emission color of at least one adjacent light-emitting device or pixel.Alternatively, an emission center substance contained in the light-emitting layer of the tandem light-emitting device preferably has a structure different from that of an emission center substance contained in a light-emitting layer of at least one adjacent light-emitting device.

[0045] The light-emitting device of one embodiment of the present invention having such a structure can exhibit high power efficiency, low energy loss, and advantageous characteristics. A display device of one embodiment of the present invention including such a light-emitting device can achieve low power consumption, high reliability, high luminance display, and high visibility.

[0046] An electron transport layer included in a light-emitting unit on the anode side preferably has a multilayer structure to reduce power consumption.

[0047] The electron-transport layer included in the anode-side light-emitting device may have a multilayer structure or a single-layer structure. When the electron-transport layer has a multilayer structure, the light-emitting device can exhibit high current efficiency, low power consumption, and advantageous properties. When the electron-transport layer has a single-layer structure, the number of film formation chambers can be reduced, which is advantageous in terms of manufacturing costs.

[0048] The second organic compound with the phenanthroline skeleton can be any substance that can transport more electrons than holes, and preferably has an electron mobility higher than or equal to 1 × 10 -7 cm 2 / Vs, preferably higher than or equal to 1 × 10 -6 cm 2 / Vs when the square root of the electric field strength [V / cm] is 600.

[0049] The second organic compound having the phenanthroline skeleton preferably comprises the phenanthroline skeleton and an aromatic ring. The aromatic ring is preferably a monocyclic aromatic ring, a polycyclic aromatic ring, or the like.

[0050] Examples of the monocyclic aromatic ring include a benzene ring, a pyrrole ring, a pyridine ring, and a pyrimidine ring. Preferred examples of the polycyclic aromatic ring include heteroaromatic rings such as a phenanthroline ring and a pyrrole ring, and aromatic hydrocarbon rings such as a naphthalene ring, a phenanthrene ring, a chrysene ring, a triphenylene ring, and a fluorene ring. It is particularly preferred that the second organic compound has a plurality of such polycyclic aromatic rings to improve its heat resistance and electron-transport property.

[0051] The second organic compound having the phenanthroline skeleton may, for example, be an organic compound having a heteroaromatic ring with a phenanthroline skeleton, such as: B. Bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: mTpPPhen), 2-phenyl-9-(2-triphenylenyl)-1,10-phenanthroline (abbreviation: Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1-naphthalenyl]-1,10-phenanthroline (abbreviation: PnNPhen) or 2-[4-(2-Triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: pTpPPhen), and is particularly preferably PnNPhen (200) or mPPhen2P (201), which is represented by the following structural formula (200) or (201), or the like.

[0052] In the light-emitting device of one embodiment of the present invention, the intermediate layer may have any structure as long as it contains the second organic compound having a phenanthroline skeleton and can inject electrons and holes into the anode-side light-emitting unit and the cathode-side light-emitting unit, respectively, that are in contact with the intermediate layer by applying a voltage between a first electrode and a second electrode. Note that the intermediate layer preferably has a multilayer structure consisting of a first layer containing the second organic compound and a second layer that is closer to the cathode than the first layer.

[0053] The first layer preferably contains a metal or metal compound in addition to the second organic compound. The metal or metal compound is preferably an alkali metal (a Group 1 element), such as Li; an alkaline earth metal (a Group 2 element), such as Mg or Ca; a Group 3 element including Y and lanthanides, such as Eu and Yb; a Group 11 element, such as Cu, Ag, or Au; a Group 12 element, such as Zn; or an earth metal (a Group 13 element), such as Al or In.

[0054] Note that the first layer may have a multilayer structure composed of a layer containing an organic compound and a layer containing a metal or metal compound, positioned closer to the cathode than the layer containing an organic compound, or the first layer may be a mixed layer of an organic compound and a metal or metal compound. The first layer is preferably the mixed layer, in which case it requires a smaller number of film formation chambers and lowers the manufacturing cost, and contributes to improving the stability of the light-emitting device.

[0055] In the case where the organic compound and the metal or metal compound are mixed, there is a tendency for the organic compound and the metal or metal compound to have substantially the same distribution when the first layer is analyzed in the thickness direction. That is, if the organic compound is uniformly distributed, the metal or metal compound will also be substantially uniformly distributed.In the case of the multilayer structure composed of the layer containing the organic compound and the layer containing the metal or metal compound, in some cases the metal or metal compound diffuses from the layer containing the metal or metal compound and is also detected in a different area than the layer, but it has a distribution different from that of the organic compound; therefore, the analysis results of diffusion and mixing can be distinguished from each other.

[0056] In the case where the metal or metal compound is detected over a region having a thickness greater than or equal to 10 nm, preferably greater than or equal to 15 nm, more preferably greater than or equal to 20 nm, when the first layer is analyzed in the thickness direction, the first layer can be regarded as comprising a mixed layer in which the organic compound and the metal or metal compound are mixed.

[0057] The metal or a metal of the metal compound is preferably a substance having a donor property with respect to the second organic compound. Examples of the substance having a donor property with respect to the second organic compound include metals belonging to Groups 1 and 2; lithium or a lithium compound is particularly preferred. In particular, Li, lithium fluoride (LiF), lithium oxide (Li2O), 8-hydroxyquinolinato lithium (abbreviation: Liq), or the like is preferred. In the case where the first layer contains the second organic compound and the substance having a donor property with respect to the second organic compound, electrons are generated by charge separation, and the electrons are injected into the light-emitting unit on the anode side via the second organic compound when a voltage is applied between the first electrode and the second electrode.Therefore, the light-emitting device of one embodiment of the present invention can have a low operating voltage.

[0058] The second organic compound, in addition to the organic compound described above, is preferably an organic compound having a phenanthroline skeleton with an electron-donor substituent. The phenanthroline skeleton is likely to interact with the metal or the like, and when the second organic compound having such a phenanthroline skeleton further has an electron-donor group, the phenanthroline skeleton can have a higher electron density and a higher probability of interacting with the metal or metal compound. In particular, the use of a metal belonging to Group 3, Group 11, Group 12, or Group 13 as the metal or a metal of the metal compound makes it possible to provide a tandem light-emitting device that prevents an increase in driving voltage and has advantageous properties.

[0059] Specific examples of the electron-donating group include an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group. Note that examples of the electron-donating group preferably introduced into the phenanthroline ring are not limited to the above examples. The electron-donating group may be any group that can increase the electron density of the phenanthroline ring by being introduced into the phenanthroline ring. The electron-donating group may be introduced into the phenanthroline ring via an arylene group, such as a phenylene group, and the arylene group is preferably a p-phenylene group.

[0060] Concrete examples of the organic compound with the phenanthroline skeleton with the electron donor substituent are shown in the structural formulas (300) to (310).

[0061] The electron transport layer included in the light-emitting unit on the cathode side has a multilayer structure as described above, and among stacked layers, a layer on the cathode side preferably contains a first organic compound having a triazine skeleton.

[0062] The first organic compound with the triazine skeleton can be any substance that can transport more electrons than holes, and preferably has an electron mobility higher than or equal to 1 × 10 -7 cm 2 / Vs, preferably higher than or equal to 1 × 10 -6 cm 2 / Vs in the case where the square root of the electric field strength [V / cm] is 600.

[0063] The first organic compound having the triazine skeleton preferably has the triazine skeleton and an aromatic ring. The aromatic ring is preferably a monocyclic aromatic ring, a polycyclic aromatic ring, an aromatic ring having an alkyl group as a substituent, an aromatic ring having a fluorine group as a substituent, an aromatic ring having a cyano group as a substituent, or the like. The triazine skeleton may have a substituent other than the above-described aromatic ring, and the aromatic ring may have a substituent other than the above-described fluorine group, cyano group, or alkyl group. Note that the triazine skeleton is also referred to as a triazine ring, and other skeletons can also be reformulated as rings.

[0064] Examples of the monocyclic aromatic ring include aromatic hydrocarbon rings such as a benzene ring, and heteroaromatic rings such as a pyrrole ring, a pyridine ring, a pyrimidine ring, and a triazine ring. By having the aromatic ring as a substituent, there are, for example, effects of improving heat resistance, particularly a glass transition temperature (Tg), and an effect of improving an electron transport property.

[0065] Examples of the polycyclic aromatic ring include aromatic hydrocarbon rings such as a naphthalene ring, a phenanthrene ring, a chrysene ring, a triphenylene ring, a fluorene ring, and a spirobifluorene ring, and heteroaromatic rings such as a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, a xanthene ring, an indolocarbazole ring, and an indenocarbazole ring. A compound having the polycyclic aromatic ring as a substituent is more preferable than a compound having the monocyclic aromatic ring such as a benzene ring because it can improve heat resistance. A compound having, as a substituent, a ring in which an aromatic ring (e.g., a benzene ring, a naphthalene ring, or a pyridine ring) is further condensed with any of the above polycyclic aromatic rings can further improve heat resistance.Examples of the ring in which an aromatic ring is further condensed with the polycyclic aromatic ring include a benzofluorene ring, a benzonaphthofuran ring, a benzoxanthene ring, and a benzonaphthothiophene ring. By providing a layer containing a compound with high heat resistance near the cathode, heat damage to the device can be prevented when high-temperature treatment is performed in a patterning step or the like after the layer or the cathode is formed.

[0066] Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a tertiary butyl group, a cyclohexyl group, and an adamantyl group. The first organic compound having the alkyl group as a substituent can have a low refractive index, and a layer containing the first organic compound can have a low refractive index. This can prevent total reflection at the interface between the layer and another layer and improve the light extraction efficiency of the light-emitting device comprising the layer. An organic compound having an alkyl group with a plurality of carbon atoms, preferably three or more carbon atoms, more preferably four or more carbon atoms, even more preferably five or more carbon atoms, can increase the effect of reducing the refractive index.

[0067] When such a compound containing an alkyl group is also used for the hole-transport layer, the refractive index of the hole-transport layer can be reduced. In particular, when a compound containing a triazine skeleton and an alkyl group is used for the electron-transport layer, and a compound containing an aromatic amine skeleton and an alkyl group is used for the hole-transport layer, the effect of improving light extraction efficiency can be synergistically enhanced.

[0068] A layer containing a compound with a fluorine group as a substituent is also preferred because it can reduce the refractive index. In particular, an organic compound containing a plurality of fluorine groups can enhance the refractive index-lowering effect. It is also effective to use a compound with a fluorine group for both the electron-transport layer and the hole-transport layer.

[0069] A compound having a structure in which a plurality of alkyl groups or fluorine groups are bonded to an aromatic ring can further reduce the refractive index of the layer. In one example, two or three or more tertiary butyl groups are bonded to a benzene ring as substituents. Without being limited to the benzene ring, the plurality of alkyl groups or fluorine groups may be bonded to another monocyclic aromatic ring, such as a pyridine ring, or a polycyclic aromatic ring, such as a fluorene ring. In addition, the plurality of alkyl groups or fluorine groups are suitably bonded to one or more rings contained in a polycyclic aromatic ring (e.g., a naphthalene ring, a fluorene ring, a carbazole ring, a quinoline ring, or a xanthene ring). In one example, a plurality of tertiary butyl groups are bonded to a benzene ring in a fluorene ring.

[0070] The first organic compound with a cyano group as a substituent is preferred because it can improve the electron transport property.

[0071] A combination of some polycyclic aromatic rings, alkyl groups, fluorine groups, and cyano groups is also suitable for substituents of the first organic compound. For example, by including a polycyclic aromatic ring and a cyano group as substituents, both heat resistance and electron transport properties can be improved. Furthermore, by including a polycyclic aromatic ring and an alkyl group, both heat resistance and light extraction efficiency can be improved. In this way, substituents can be combined according to the required function.

[0072] The first organic compound having a plurality of polycyclic aromatic rings as substituents can further improve heat resistance. In this case, the first organic compound preferably has the aromatic hydrocarbon ring and the heteroaromatic ring.

[0073] The first organic compound having the triazine skeleton can be, in particular, for example, an organic compound having a heteroaromatic ring with a triazine skeleton, such as 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (Abbreviation: mFBPTzn), 5-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(Dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(Triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-Diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(Biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4', 1"-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 2-[4-(2-Naphthalenyl)phenyl]-4-phenyl-6-spiro[9H-fluoren-9,9'-[9H]xanthen]-4-yl-1,3,5-triazine (abbreviation: βNP-SFx(4)Tzn), 9,9'-{6-[3-(Triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviation: SiTrzCz2), 2-Phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviation: mSiTrz), 11-[4-(Biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviation: BP-mBPIcz(II)Tzn), 3-{3-[9-(4,6-Diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]phenyl}-9-phenyl-9H-carbazole (abbreviation: mPCPDBfTzn), 9,9'-[6-(Biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3"-diyl]bis(9H-carbazole) (Abbreviation: CzpmCzBPTzn), 3-Pheny-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl-1,3,5-triazin-2-yl]-9H-carbazole (Abbreviation: PDBf-PCzTzn), 9-[4-(4,6-Diphenyl-1,3,5-triazin-2-y)-2-dibenzothienyl]-2-phenyl-9H-carbazole (Abbreviation: PCzDBtTzn), 2,4-Diphenyl-6-[3'-(spiro[7H-benzo[c]fluoren-7,9'-[9H]xanthen]-2'-yl)biphenyl-3-yl]-1,3,5-triazine (Abbreviation: mSbfxBPTzn), 3'-[4-Phenyl-6-(spiro[9H-fluoren-9,9'-[9H]xanthen]-2'-yl)-1,3,5-triazin-2-yl]biphenyl-4-carbonitrile (Abbreviation: mpCNBP-SFxTzn) or 2,2'-[1,2-naphthalenediyldi(4,1-phenylene)]bis(4,6-diphenyl-1,3,5-triazine) (abbreviation: TznP2N), and is particularly preferably TznP2N (100), mSbfxBPTzn (101), mpCNBP-SFxTzn (102), CNBPNPTzn (103), βNP-SFx(4)Tzn (104),mmtBuBP-mDMePyPTzn (105) or mBnfBPTzn (106), represented by the following structural formulas (100) to (106), or the like. Note that any of the above organic compounds deuterated as needed can also be used.

[0074] Note that, as described above, the electron-transport layer included in the anode-side light-emitting unit may have a multilayer structure or a single-layer structure. In the case of the multilayer structure, a layer included in the multilayer structure and positioned on the intermediate layer side preferably contains a third organic compound having a triazine skeleton to reduce the operating voltage and power consumption, and the layer preferably contains a fourth organic compound not having a triazine skeleton to appropriately control electron transport from the intermediate layer.

[0075] It should be noted that the first layer preferably contains a Group 1 or Group 2 element, particularly lithium or a lithium compound, and the second organic compound having a phenanthroline skeleton with an electron-donor substituent. In this case, the tandem light-emitting device can have a lower operating voltage and higher reliability. Furthermore, the first layer preferably contains a Group 1 or Group 2 element, particularly lithium or a lithium compound, and the second organic compound having a phenanthroline skeleton with an electron-donor substituent. In this case, an increase in the operating voltage due to processing the organic compound layer of the light-emitting device by a photolithography method can be prevented.

[0076] In the intermediate layer having the structure described above, the second organic compound is particularly preferably an organic compound having a 1,10-phenanthroline skeleton among phenanthroline skeletons, in which case the second organic compound is likely to interact with the metal or the metal compound because two nitrogen atoms of the organic compound can be coordinated to the metal.

[0077] In the case where an electron-donor group is introduced into a 1,10-phenanthroline skeleton, it is preferentially substituted with the electron-donor group at the 4- and 7-positions of the 1,10-phenanthroline skeleton. By introducing an electron-donor group into the 4- and 7-positions of the 1,10-phenanthroline skeleton, the electron density of the nitrogen atoms at the 1- and 10-positions can be increased, thereby facilitating interaction with the metal or metal compound.

[0078] The first layer may further contain an organic compound different from the second organic compound. Note that the different organic compound preferably has an electron-transport property. It is particularly preferable that the organic compound has two or more heteroaromatic rings bonded or condensed together, and that the two or more heteroaromatic rings have a total of three or more heteroatoms. The first layer containing such an organic compound can improve heat resistance, electron-transport property, and the like.

[0079] The second layer preferably contains a fifth organic compound with a hole transport property.

[0080] The second layer preferably further contains a substance having an acceptor property, and the substance having an acceptor property is preferably an organic compound having an acceptor property with respect to the fifth organic compound. The substance having an acceptor property is particularly preferably an organic compound having a halogen group and / or a cyano group, more preferably an organic compound having fluorine and / or a cyano group. Note that it is more preferable that the total number of halogen groups (fluorine) and cyano groups of the organic compound is four or more. That is, the second layer preferably contains a halogen, especially fluorine.

[0081] In the case where the second layer contains the fifth organic compound and the substance having an acceptor property with respect to the fifth organic compound, holes are generated by charge separation, and the holes are injected into the light-emitting unit on the cathode side via the fifth organic compound when a voltage is applied between the first electrode and the second electrode. Therefore, the light-emitting device of one embodiment of the present invention can have a low operating voltage.

[0082] The intermediate layer may comprise a third layer between the first layer and the second layer.

[0083] The third layer contains a substance having an electron transport property and has functions such as smoothly transmitting and receiving electrons between the first layer and the second layer to reduce the operating voltage and reducing the interaction between the first layer and the second layer to improve reliability.

[0084] The LUMO level of the substance having an electron transport property contained in the third layer is preferably between the LUMO level of the substance having an acceptor property in the second layer and the LUMO level of the organic compound in a layer (e.g., the electron transport layer in the light-emitting unit on the anode side) that is in contact with the first layer in the light-emitting unit on the anode side.

[0085] A specific energy level of the LUMO level of the substance having an electron-transport property used in the third layer is preferably higher than or equal to -5.0 eV, more preferably higher than or equal to -5.0 eV and lower than or equal to -3.0 eV, even more preferably higher than or equal to -4.30 eV and lower than or equal to -3.00 eV, even more preferably higher than or equal to -4.30 eV and lower than or equal to -3.30 eV, in which case, an increase in the operating voltage can be prevented. Note that the substance having an electron-transport property used in the third layer is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0086] The thickness of the third layer is preferably greater than or equal to 1 nm and less than or equal to 10 nm, more preferably greater than or equal to 2 nm and less than or equal to 5 nm, in which case an increase in the operating voltage can be prevented.

[0087] The light-emitting device of one embodiment of the present invention having the above structure can achieve high power efficiency, low energy loss, and advantageous characteristics. A display device of one embodiment of the present invention including such a light-emitting device can achieve low power consumption, high reliability, high luminance display, and high visibility.

[0088] Next, light-emitting devices of an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1A illustrates a light-emitting device 130 of one embodiment of the present invention. The light-emitting device of one embodiment of the present invention is a tandem light-emitting device and includes an organic compound layer 103 (also referred to as an EL layer) comprising a first light-emitting unit 501 comprising a first light-emitting layer 113_1, a second light-emitting unit 502 comprising a second light-emitting layer 113_2 and a second electron-transport layer 114_2 (a layer arrangement of a second electron-transport layer 114_2a and a second electron-transport layer 114_2b), and an intermediate layer 116 between a first electrode 101 comprising an anode and a second electrode 102 comprising a cathode.It should be noted that the first light-emitting unit may comprise a first electron transport layer 114_1 between the first light-emitting layer 113_1 and the intermediate layer 116.

[0089] In the light-emitting device 130, the second electron-transport layer 114_2 has a multilayer structure composed of the second electron-transport layer 114_2a and the second electron-transport layer 114_2b. The second electron-transport layer 114_2b is positioned between the second electron-transport layer 114_2a and the cathode. The intermediate layer 116 contains the second organic compound having a phenanthroline framework.

[0090] Note that the second electron-transport layer 114_2b preferably contains the first organic compound having a triazine skeleton to reduce power consumption. The second electron-transport layer 114_2b containing the first organic compound having a triazine skeleton is preferably in contact with the second electrode 102 to improve its electron injection property, thereby reducing the operating voltage and power consumption.

[0091] Although light-emitting devices each comprising an intermediate layer 116 and two light-emitting units are described as examples in this embodiment, a light-emitting device comprising n intermediate layers (n is an integer greater than or equal to 1) and n+1 light-emitting units may be used. For example, the light-emitting device shown in Fig. 1B illustrates an example of a tandem light-emitting device comprising the first light-emitting unit 501, a first intermediate layer 116_1, the second light-emitting unit 502, a second intermediate layer 116_2, and a third light-emitting unit 503, where n = 2.

[0092] The first light-emitting unit 501 and the second light-emitting unit 502 may include a functional layer in addition to the above-described light-emitting layers and the above-described electron-transport layers. Although Fig. 1A illustrates the structure in which the first light-emitting unit 501 is provided with a hole-injection layer 111 and a first hole-transport layer 112_1 in addition to the first light-emitting layer 113_1 and the first electron-transport layer 114_1, and the second light-emitting unit 502 is provided with a second hole-transport layer 112_2 in addition to the second light-emitting layer 113_2 and the second electron-transport layer 114_2. However, the structure of the organic compound layer 103 in one embodiment of the present invention is not limited thereto, and any of the layers may be omitted, or other layers may be added. Typical examples of the other layers include a charge blocking layer and an exciton blocking layer.

[0093] The first electrode 101 comprises the anode. The first electrode 101 may have a multi-layer structure, in which case a layer in contact with the organic compound layer 103 serves as the anode. The anode is preferably formed, for example, using a metal, an alloy, a conductive compound, or a mixture thereof, each having a high work function (in particular, higher than or equal to 4.0 eV). Specific examples include indium oxide-tin oxide (ITO), indium oxide-tin oxide containing silicon or silicon oxide, indium oxide-zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). Films of such conductive metal oxides are generally formed by a sputtering method, but may be formed by a sol-gel method or the like. For example, a film of indium oxide-zinc oxide is formed by a sputtering method using a target in which 1 wt.-% to 20 wt.% zinc oxide is added to indium oxide. Furthermore, an indium oxide film containing tungsten oxide and zinc oxide (IWZO) can be formed by a sputtering method using a target in which 0.5 wt.% to 5 wt.% tungsten oxide and 0.1 wt.% to 1 wt.% 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), a nitride of a metal material (e.g., titanium nitride), or the like can be used for the anode. Graphene can also be used for the anode. It should be noted that an electrode material can be selected independently of the work function if the composite material forming the second layer 117 is used in the above intermediate layer 116 for the layer (typically the hole injection layer) in contact with the anode.

[0094] The hole injection layer 111 is provided in contact with the anode and has a function of facilitating the injection of holes into the organic compound layer 103 (the first light-emitting unit 501). The hole injection layer 111 can be formed, for example, using a phthalocyanine-based compound or a complex compound such as phthalocyanine (abbreviation: H2Pc) or copper phthalocyanine (abbreviation: CuPc), an aromatic amine compound such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or a high molecular compound such as phthalocyanine. B. Poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS).

[0095] The hole-injection layer 111 can be formed using a substance having an electron-accepting property. Examples of the substance having an accepting property include organic compounds having an electron-withdrawing group (e.g., a halogen group or a cyano group), such as cyano group. E.g., 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. A compound in which electron-withdrawing groups are bonded to a fused aromatic ring containing a plurality of heteroatoms, such as HAT-CN, is particularly preferred because of its thermal stability. A [3]radialene derivative containing an electron-withdrawing group (especially a cyano group, a halogen group, such asa fluorine group, or the like) has a very high electron accepting property and is thus preferred. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. As a substance having an acceptor property, in addition to the organic compounds described above, a transition metal oxide such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, or manganese oxide can be used. Alternatively, the hole injection layer 111 may be formed, for example, using a phthalocyanine-based compound or a complex compound such as phthalocyanine (abbreviation: H2Pc) or copper phthalocyanine (abbreviation: CuPc), an aromatic amine compound such as4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or a high-molecular-weight compound such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS). The substance with an acceptor property can extract electrons from an adjacent hole-transport layer (or hole-transport material) by applying an electric field.

[0096] The hole injection layer 111 is preferably formed using a composite material containing any of the above-mentioned materials having an acceptor property and a substance having a hole transport property.

[0097] As a substance having a hole-transporting property used in the composite material, any of various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and high-molecular compounds (e.g., oligomers, dendrimers, and polymers) can be used. Note that the substance having a hole-transporting property used for the composite material preferably has a hole mobility of 1 × 10 -6 cm 2 / Vs or higher. The substance having a hole-transporting property used in the composite material is preferably a compound having a condensed aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the condensed aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferred. As the π-electron-rich heteroaromatic ring, a condensed aromatic ring having at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton in the ring is preferred; in particular, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further condensed with a carbazole ring or a dibenzothiophene ring is preferred.

[0098] Such a substance having a hole-transport property more preferably has any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. Specifically, an aromatic amine having a substituent with a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to nitrogen of an amine via an arylene group can be used. Note that the substance having a hole-transport property preferably has an N,N-bis(4-biphenyl)amino group to enable the fabrication of a light-emitting device with a long lifetime.

[0099] Specific examples of the substance with a hole transport property include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (Abbreviation: BBABnf(8)), N,N-Bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (Abbreviation: BBABnf(II)(4)), N,N-Bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (Abbreviation: DBfBB1TP), N-[4-(Dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (Abbreviation: ThBA1BP), 4-(2-Naphthyl)-4',4''-diphenyltriphenylamine (Abbreviation: BBAßNB), 4-[4-(2-Naphthyl)phenyl]-4',4''-diphenyltriphenylamine (Abbreviation: BBAßNBi), 4,4'-Diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (Abbreviation: BBAαNβNB), 4,4'-Diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-Diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPßNB-03), 4,4'-Diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(ßN2)B), 4,4'-Diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-Diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-Diphenyl-4''-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-Biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-Biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-Biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-Phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4'-Bis(1-naphthyl)triphenylamine (Abbreviation: αNBB1BP), 4,4'-Diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (Abbreviation: YGTBi1BP),4'-[4-(3-Phenyl-9H-carbazol-9-yl)phenyl]tris(biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(Carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBiβNB), N-[4-(9-Phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-Bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-Bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-Naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi),4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(Biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-Bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-Bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-Bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, 9-[3-(Triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz) and 9'-phenyl-9'H-9,3':6',9''-tercarbazole (abbreviation: PSiCzGI).

[0100] Examples of the aromatic amine compounds that can be used as a substance with a hole-transporting property include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD) and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0101] The formation of the hole injection layer 111 can improve the hole injection property, resulting in the light-emitting device being able to operate at a low voltage.

[0102] Among substances with an acceptor property, an organic compound with an acceptor property is easily used because the organic compound is easily deposited as a film by evaporation.

[0103] The hole-transport layer (the first hole-transport layer 112_1 or the second hole-transport layer 112_2) contains an organic compound having a hole-transport property. The organic compound having a hole-transport property preferably has a hole mobility of 1 × 10 -6 cm 2 / Vs or higher.

[0104] Examples of the above-mentioned substance having a hole-transporting property include the following compounds: Compounds having an aromatic amine skeleton, such as: B. 4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-Diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-Bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-Diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF) and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluoren]-2-amine (abbreviation: PCBASF); compounds with a carbazole skeleton, such as B. 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-Naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP), 9-(3-Biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-Biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-Di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-(2-Naphthyl)-9'-[1,1':4',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-[1,1':3',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-[1,1':3',1''-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-[1,1':4',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazol, 9-Phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazol (Abkürzung: PCCzTp), 9,9'-Bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazol, 9-(4-Biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazol, 9-(Triphenylen-2-yl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazol, N,N-Bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amin und 9-[3-(Triphenylsilyl)phenyl]-3,9'-bi-9H-carbazol (Abkürzung: PSiCzCz); Verbindungen mit einem Thiophen-Gerüst, wie z. B. 4,4',4''-(Benzol-1,3,5-triyl)tri(dibenzothiophen) (Abkürzung: DBT3P-II), 2,8-Diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV); and compounds with a furan skeleton, such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above materials, the compound having an aromatic amine skeleton and the compound having a carbazole skeleton are preferred because these compounds are highly reliable and have a high hole-transport property, contributing to a reduction in operating voltage. Any of the organic compounds cited as examples of the substance having a hole-transport property used for the composite material in the hole-injection layer 111 may be used.can also be suitably used as a material contained in the hole-transport layer. Note that any of the above organic compounds, deuterated as needed, can also be used.

[0105] It should be noted that the first hole transport layer 112_1 and the second hole transport layer 112_2 preferably contain organic compounds having the same framework and more preferably contain the same compound.

[0106] The light-emitting layer (the first light-emitting layer 113_1 and the second light-emitting layer 113_2) preferably contains an emission center substance and a host material. The light-emitting layer may additionally contain another material.

[0107] The first light-emitting layer 113_1 and the second light-emitting layer 113_2 preferably emit light of similar colors. For example, red, green, and blue pixels are often used in a full-color display device. In a light-emitting device used in a red pixel, both the first light-emitting layer 113_1 and the second light-emitting layer 113_2 emit red light. In a green pixel, the two light-emitting layers emit green light. In a blue pixel, the two light-emitting layers emit blue light.In this case, the emission center substance contained in the first light-emitting layer 113_1 and the emission center substance contained in the second light-emitting layer 113_2 are preferably compounds whose emission spectra have a maximum peak wavelength difference of less than or equal to 30 nm, more preferably less than or equal to 20 nm, and even more preferably less than or equal to 10 nm. Note that more preferably, the first light-emitting layer 113_1 and the second light-emitting layer 113_2 contain the same emission center substance.

[0108] The emission center substance can be a fluorescent substance, a phosphorescent substance, a substance that emits thermally activated delayed fluorescence (TADF), or another light-emitting substance.

[0109] Examples of the fluorescent substance that can be used as the emission center substance in the light-emitting layer are as follows. Other fluorescent substances can also be used.

[0110] Examples include 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-Bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-Carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-Carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-Diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), Perylene, 2,5,8,11-Tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis(N,N',N'-triphenyl-1,4-phenylenediamine) (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N,N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysen-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, 9,10-diphenyl-2-[N-phenyl-N-(9-phenyl-carbazol-3-yl)-amino]-anthracene (abbreviation: 2PCAPA), N-[9,10-Bis(biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-Diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-Bis(biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-Bis(biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-Triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-Diphenylquinacridone (abbreviation: DPQd), Rubrene, 5,12-Bis(biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT),2-(2-{2-[4-(Dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-Methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[lj]chlinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-Tetrakis(4-methylphenyl)tetracen-5,11-diamine (abbreviation: p-mPhTD), 7,14-Diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-Isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ijlquinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-Butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-Bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-Diphenyl-N,N'-(1,6-pyrenediyl)bis[(6-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02). Condensed aromatic diamine compounds, typically pyrenediamine compounds, such as B. 1,6FLPAPrn, 1,6mMemFLPAPrn and 1,6BnfAPrn-03, are particularly preferred due to their high hole-trapping properties, high emission efficiency or high reliability.

[0111] Examples of the phosphorescent substance that can be used as the emission center substance in the light-emitting layer are as follows.

[0112] The examples include organometallic iridium complexes with a 4H-triazole framework, such as Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN 2 ]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp) 3] ) and tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz) 3] ); organometallic iridium complexes with a 1H-triazole framework, such as B. Tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3] and Tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]); organometallic iridium complexes with an imidazole framework, such as fac-Tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpim)3]), Tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]) and tris(2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazol-2-yl-κN 3}-4-cyanophenyl-κC)iridium(III) (abbreviation: CNImlr); organometallic complexes with a benzimizazolidene framework, such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC 2 )phenyl-κC]iridium(III) (abbreviation: [Ir(cb)3]); organometallic iridium complexes in which a phenylpyridine derivative with an electron-withdrawing group is a ligand, such as bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III)tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III)picolinate (abbreviation: Flrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2'}iridium(III)picolinate (abbreviation: [Ir(CF3ppy)2(pic)]) and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III)acetylacetonate (abbreviation: Flracac); and platinum complexes, such as (2-{3-[3-(3,5-Di-tert-butylphenyl)benzimidazol-1-yl-2-ylidene-κC 2 ]phenoxy-κC 2}-9-(4-tert-butyl-2-pyridinyl-κN)carbazole-2,1-diyl-κC1 )platinum(II) (abbreviation: PtON-TBBI). These compounds emit blue phosphorescence light and exhibit an emission peak in the wavelength range of 450 nm to 520 nm. Alternatively, a compound obtained by substituting part of the hydrogen with deuterium in any of these compounds can also be used.

[0113] Further examples include organometallic iridium complexes with a pyrimidine framework, such as: B. Tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), Tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (Acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (Acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (Acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (Acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]) and (Acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]); organometallic iridium complexes with a pyrazine framework, such as(Acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]); organometallic iridium complexes with a pyridine framework, such as tris(2-phenylpyridinato-N,C 2' )iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2' )iridium(III)acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2' )iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2' )iridium(III)acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN 2)phenyl-κC]iridium(III) (Abkürzung: [Ir(5mppy-d3)2(mbfpypy-d3)]), {2-(Methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro[2,3-b]pyridin-7-yl-κC}bis{5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC}iridium(III) (Abkürzung: [Ir(5mtpy-d6)2(mbfpypy-iPr-d4)]), [2-d3-Methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridin-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (Abkürzung: [Ir(ppy)2(mbfpypy-d3)]), [2-(4-Methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (Abkürzung: [Ir(ppy)2(mdppy)]), [2-(4-d3-Methyl-5-phenyl-2-pyridinyl-κN 2 )phenyl-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN 2)phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy-d3)2(mdppy-d3)]), [2-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-ĸN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mbfpypy)]), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium (abbreviation: [Ir(ppy)2(mdppy)]) and Tris{2-[5-(methyl-d3)-4-phenyl-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: [Ir(5m4dppy-d3)3]); and rare earth metal complexes, such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). These compounds emit mainly green phosphorescence light and exhibit an emission peak in the wavelength range of 500 nm to 600 nm. It should be noted that organometallic iridium complexes with a pyrimidine framework exhibit significantly high reliability or significantly high emission efficiency and are therefore particularly preferred.Alternatively, a compound obtained by substituting a portion of hydrogen with deuterium in any of these compounds may also be used.

[0114] Further examples include organometallic iridium complexes with a pyrimidine framework, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]) and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]); organometallic iridium complexes with a pyrazine framework, such as B. (Acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]) and (Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]); organometallic iridium complexes with a pyridine framework, such as tris(1-phenylisoquinolinato-N,C 2' )iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2')iridium(III)acetylacetonate (abbreviation: [Ir(piq)2(acac)]), (3,7-diethyl-4,6-nonanedionato-κO 4 ,κO 6 )bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC]iridium(III) and (3,7-diethyl-4,6-nonanedionato-κO 4 ,κO 6)bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC]iridium(III); platinum complexes, such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviation: PtOEP); and rare earth metal complexes, such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]). These compounds emit red phosphorescence light and exhibit an emission peak in the wavelength range of 600 nm to 700 nm. Furthermore, the organometallic iridium complexes with a pyrazine framework can provide red light emission with favorable chromaticity. Alternatively, a compound obtained by substituting part of the hydrogen with deuterium in any of these compounds can also be used.

[0115] It should be noted that in one embodiment of the present invention, the use of a deuterated compound as the emission center substance improves the emission efficiency. Therefore, the emission center substance is preferably a deuterated material.

[0116] In addition to the above phosphorescent compounds, known phosphorescent compounds can also be selected and used.

[0117] Examples of the TADF material include a fullerene, a derivative thereof, an acridine, a derivative thereof, and an eosin derivative. Further, a metal-containing porphyrin, such as a porphyrin containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), can be cited. Examples of the metal-containing porphyrin include a protoporphyrin-tin fluoride complex (SnF2(Proto IX)), a mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), a hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), a coproporphyrin-tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), an octaethylporphyrin-tin fluoride complex (SnF2(OEP)), an etioporphyrin-tin fluoride complex (SnF2(EtioI)) and an octaethylporphyrin-platinum chloride complex (PtCl2OEP), which are represented by the following structural formulas.

[0118] Alternatively, a heterocyclic compound having a π-electron-rich heteroaromatic ring and / or a π-electron-poor heteroaromatic ring and represented by the following structural formulas, such as: B. 2-(Biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn) (Abbreviation: PXZ-TRZ), 3-[4-(5-Phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-Dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), Bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS) or 10-Phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA) can be used.Such a heterocyclic compound is preferred because it exhibits high electron-transport and hole-transport properties due to a π-electron-rich heteroaromatic ring and a π-electron-poor heteroaromatic ring. Among frameworks containing the π-electron-poor heteroaromatic ring, a pyridine framework, a diazine framework (a pyrimidine framework, a pyrazine framework, and a pyridazine framework), and a triazine framework are preferred due to their high stability and reliability. In particular, a benzofuropyrimidine framework, a benzothienopyrimidine framework, a benzofuropyrazine framework, and a benzothienopyrazine framework are preferred due to their high acceptor properties and high reliability.Among skeletons containing the π-electron-rich heteroaromatic ring, an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton have high stability and high reliability; therefore, at least one of these skeletons is preferably included. As the furan skeleton, a dibenzofuran skeleton is preferred, and as the thiophene skeleton, a dibenzothiophene skeleton is preferred. As the pyrrole skeleton, indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferred.Note that a substance in which the π-electron-rich heteroaromatic ring is directly bonded to the π-electron-poor heteroaromatic ring is particularly preferred because both the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-poor heteroaromatic ring are improved, the energy difference between the S1 level and the T1 level becomes small, and therefore, thermally activated delayed fluorescence can be obtained with high efficiency. Note that an aromatic ring to which an electron-withdrawing group, such as a cyano group, is bonded can be used instead of the π-electron-poor heteroaromatic ring. As the π-electron-rich framework, an aromatic amine framework, a phenazine framework, or the like can be used.As the π-electron-deficient skeleton, a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring or a heteroaromatic ring having a cyano group or a nitrile group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, or the like can be used. As described above, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used instead of the π-electron-deficient heteroaromatic ring and / or the π-electron-rich heteroaromatic ring.

[0119] Alternatively, a TADF material whose singlet excitation state and triplet excitation state are in thermal equilibrium can be used. Since such a TADF material enables a short emission lifetime (excitation lifetime), the efficiency of a light-emitting device is less likely to decrease in a high luminance range. Specifically, a material with the following molecular structure can be used.

[0120] It should be noted that a TADF material is a material that has a small difference between the S1 level and the T1 level and has the function of converting triplet excitation energy into singlet excitation energy through reverse intersystem crossing. Therefore, a TADF material can upconvert triplet excitation energy into singlet excitation energy (i.e., reverse intersystem crossing) using a small amount of thermal energy and efficiently generate a singlet excited state. Furthermore, the triplet excitation energy can be converted into light emission.

[0121] An exciplex whose excited state is formed by two types of substances has a very small difference between the S1 level and the T1 level and serves as a TADF material that can convert the triplet excitation energy into the singlet excitation energy.

[0122] A phosphorescence spectrum observed at low temperature (e.g., 77 K to 10 K) is used for an index of the T1 level. When the energy level with a wavelength of the line obtained by extrapolating a tangent to the fluorescence spectrum at a tail on the short wavelength side is the S1 level, and the energy level with a wavelength of the line obtained by extrapolating a tangent to the phosphorescence spectrum at a tail on the short wavelength side is the T1 level, the difference between the S1 level and the T1 level of the TADF material is preferably less than or equal to 0.3 eV, more preferably less than or equal to 0.2 eV.

[0123] When a TADF material is used as the light-emitting substance, the S1 level of the host material is preferably higher than that of the TADF material. Furthermore, the T1 level of the host material is preferably higher than that of the TADF material.

[0124] Various charge transport materials can be used as the host material in the light-emitting layer, such as materials with an electron transport property and / or materials with a hole transport property and the TADF materials.

[0125] The material having a hole-transport property is preferably, for example, an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton. As the π-electron-rich heteroaromatic ring, a condensed aromatic ring having at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton is preferred; in particular, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further condensed with a carbazole ring or a dibenzothiophene ring is preferred.

[0126] Such a substance having a hole-transport property more preferably has any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. Specifically, an aromatic amine having a substituent with a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to nitrogen of an amine via an arylene group can be used. Note that the substance having a hole-transport property is preferably an organic compound having an N,N-bis(4-biphenyl)amino group to enable the fabrication of a light-emitting device with a long lifetime.

[0127] Preferred examples of such organic compounds include the following organic compounds: Compounds having an aromatic amine skeleton, such as: B. 4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-Diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-Bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-Diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF) and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluoren]-2-amine (abbreviation: PCBASF); compounds with a carbazole skeleton, such as B. 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 3,9-bis(9-phenyl-9H-carbazol-3-yl)-9H-carbazole (abbreviation: PCCzPC), 9-(biphenyl-4-yl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzBP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-Bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazol (Abkürzung: βNCCBP), 9,9'-Di-2-naphthyl-3,3'-9H,9'H-bicarbazol (Abkürzung: BisβNCz), 9-(2-Naphthyl)-9'-[1,1':4',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-[1,1':3',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-[1,1':3',1''-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-[1,1':4',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazol, 9-(2-Naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazol, 9-Phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazol (Abkürzung: PCCzTp), 9,9'-Bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazol, 9-(4-Biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazol, 9-(Triphenylen-2-yl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazol, N,N-Bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amin, 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazol (Abkürzung: PSiCzCz) und 9'-Phenyl-9'H-9,3':6',9''-tercarbazole (abbreviation: PSiCzGI); compounds with a thiophene skeleton, such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV); and compounds with a furan skeleton, such as B. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above materials, the compound with an aromatic amine skeleton and the compound with a carbazole skeleton are preferred because these compounds are highly reliable and exhibit high hole-transport properties, contributing to a reduction in operating voltage. In addition, the organic compounds can also be used as examples of the material with a hole-transport property.that can be used for the hole transport layer.

[0128] The material having an electron-transport property is preferably an organic compound having a π-electron-deficient heteroaromatic ring. Examples of the organic compound having a π-electron-deficient heteroaromatic ring skeleton include an organic compound having a heteroaromatic ring with a polyazole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0129] Among the above organic compounds, the organic compound having a heteroaromatic ring with a diazine skeleton (a pyrimidine skeleton, a pyrazine skeleton, or a pyridazine skeleton), the organic compound having a heteroaromatic ring with a pyridine skeleton, and the organic compound having a heteroaromatic ring with a triazine skeleton are preferred due to their high reliability. In particular, the organic compound having a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and the organic compound having a heteroaromatic ring with a triazine skeleton have a high electron transport property to contribute to a reduction in operating voltage.A benzofuropyrimidine scaffold, a benzothienopyrimidine scaffold, a benzofuropyrazine scaffold, and a benzothienopyrazine scaffold are preferred due to their high acceptor properties and high reliability.

[0130] Preferred examples of the organic compound having a π-electron-deficient heteroaromatic ring skeleton include the following organic compounds: organic compounds having an azole skeleton, such as: B. 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II) and 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOS); organic compounds with a heteroaromatic ring with a pyridine skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB),Bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), 2,2-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: mTpPPhen), 2-phenyl-9-(2-triphenylenyl)-1,10-phenanthroline (abbreviation: Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1-naphthalenyl]-1,10-phenanthroline (abbreviation: PnNPhen) and 2-[4-(2-Triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: pTpPPhen); organic compounds with a diazine skeleton, such as B. 2-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-Diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[3'-(Dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-Bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-Bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-Bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[Pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(Biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalene)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(Pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (Abbreviation: 2,6(NP-PPm)2Py), 6-(Biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (Abbreviation: 6mBP-4Cz2PPm), 2,6-Bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 7-[4-(9-Phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PCcgDBCzQz) and 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm); organic compounds with a heteroaromatic ring with a triazine skeleton, such as. B. 2-(Biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(Benzo[h]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(Benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (Abbreviation: mFBPTzn), 5-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(Dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (Abbreviation: mDBtBPTzn), 2.4,6-Tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(Biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(Triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(Biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 2-[4-(2-naphthalenyl)phenyl]-4-phenyl-6-spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl-1,3,5-triazine (abbreviation: βNP-SFx(4)Tzn), 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviation: SiTrzCz2), 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviation: mSiTrz), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-(biphenyl-3-yl)indolo[2,3-a]carbazole (abbreviation: BP-mBPIcz(II)Tzn), 3-{3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]phenyl}-9-phenyl-9H-carbazole (abbreviation: mPCPDBfTzn), 9,9'-[6-(Biphenyl-4-yl)-2-phenyl-1,3,5-triazine-4,3''-diyl]bis(9H-carbazole) (abbreviation: Cz-pmCzBPTzn), 3-Phenyl-9-[4-phenyl-6-(9-phenyl-3-dibenzofuranyl)-1,3,5-triazin-2-yl]-9H-carbazole (abbreviation: PDBf-PCzTzn) and 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothienyl]-2-phenyl-9H-carbazole (abbreviation: PCzDBtTzn). The organic compound having a heteroaromatic ring with a diazine skeleton, the organic compound having a heteroaromatic ring with a pyridine skeleton, and the organic compound having a heteroaromatic ring with a triazine skeleton are preferred due to their high reliability. In particular, the organic compound having a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeletonand the organic compound having a heteroaromatic ring with a triazine skeleton has a high electron transport property to contribute to a reduction in operating voltage.

[0131] As a TADF material that can be used as a host material, the materials mentioned above as a TADF material that can be used as an emission center substance can also be used. When the TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted into singlet excitation energy through reverse intersystem crossing and transferred to the light-emitting substance, thereby increasing the emission efficiency of the light-emitting device. Here, the TADF material serves as an energy donor, and the light-emitting substance serves as an energy acceptor.

[0132] This is very effective when the light-emitting substance is a fluorescent substance. In this case, the S1 level of the TADF material is preferably higher than that of the fluorescent substance to achieve high emission efficiency. Furthermore, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent substance. Therefore, the T1 level of the TADF material is preferably higher than that of the fluorescent substance.

[0133] Also, a TADF material that emits light whose wavelength overlaps with the wavelength of an absorption band on the lowest energy side of the fluorescent substance is preferable. This allows the excitation energy to be smoothly transferred from the TADF material to the fluorescent substance, thus efficiently obtaining light emission, which is preferable.

[0134] Carrier recombination preferably occurs in the TADF material to efficiently generate the singlet excitation energy from the triplet excitation energy through reverse intersystem crossing. It is also preferred that the triplet excitation energy generated in the TADF material is not transferred to the triplet excitation energy of the fluorescent substance. For this reason, the fluorescent substance preferably has a protecting group around a luminophore (a scaffold that generates light emission) of the fluorescent substance. A substituent without a π bond and a saturated hydrocarbon are preferably used as the protecting group. Specific examples include an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms.Furthermore, it is preferable that the fluorescent substance has a plurality of protecting groups. Substituents without a π bond have poor charge carrier transport properties, allowing the TADF material and the luminophore of the fluorescent substance to be separated from each other with little effect on charge carrier transport or charge carrier recombination. Here, a luminophore refers to an atomic group (a skeleton) that generates light emission in a fluorescent substance. The luminophore is preferably a skeleton having a π bond, more preferably an aromatic ring, and even more preferably a condensed aromatic ring or a condensed heteroaromatic ring.Examples of the luminophore include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, and a naphthobisbenzofuran skeleton. In particular, a fluorescent substance having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton is preferred due to its high fluorescence quantum yield.

[0135] In the case where a fluorescent substance is used as the emission center substance, a material having an anthracene skeleton is suitably used as the host material. Using a substance having an anthracene skeleton as the host material for the fluorescent substance makes it possible to obtain a light-emitting layer with high emission efficiency and high durability. Among the substance having an anthracene skeleton used as the host material, a substance having a diphenylanthracene skeleton, particularly a substance having a 9,10-diphenylanthracene skeleton, is chemically stable and is thus preferably used as the host material.The host material preferably has a carbazole framework because the hole injection and hole transport properties are improved. More preferably, the host material has a benzocarbazole framework in which a benzene ring is further condensed with a carbazole framework. The HOMO level thereof is approximately 0.1 eV shallower than that of the host material having a carbazole framework, thereby allowing holes to easily penetrate the host material. In particular, the host material preferably has a dibenzocarbazole framework. The HOMO level thereof is approximately 0.1 eV shallower than that of the host material having a carbazole framework, thereby allowing holes to easily penetrate the host material, improving the hole transport property and increasing the heat resistance. Consequently, a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole or dibenzocarbazole skeleton) is more preferred as a host material.It should be noted that in view of the hole injection and hole transport properties described above, a benzofluorene framework or a dibenzofluorene framework can be used instead of a carbazole framework.Examples of such a substance include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-Phenyl-10-[4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl]anthracene (abbreviation: FLPPA), 9-(1-Naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 9-(1-Naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-Phenylanthracen-9-yl)dibenzofuran, 2-(10-Phenyl-9-anthracenyl)benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-Naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βNmβNPAnth) and 1-{4-[10-(biphenyl-4-yl)-9-anthracenyl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA).In particular, CzPA, cgDBCzPA, 2mBnfPPA and PCzPA have excellent properties and are thus preferably selected.

[0136] Note that the host material may be a mixture of several types of substances; in the case of using a mixed host material, it is preferable to mix a material having an electron-transport property with a material having a hole-transport property. By mixing the material having an electron-transport property with the material having a hole-transport property, the transport property of the light-emitting layer (the first light-emitting layer 113_1 and the second light-emitting layer 113_2) can be easily adjusted, and a recombination range can be easily controlled. The weight ratio of the content of the material having a hole-transport property to the content of the material having an electron-transport property can be 1:19 to 19:1.

[0137] Note that a phosphorescent substance can be used as part of the mixed material. When a fluorescent substance is used as the light-emitting substance, a phosphorescent substance can be used as an energy donor to supply excitation energy to the fluorescent substance.

[0138] These mixed materials can form an exciplex. These mixed materials are preferably selected to form an exciplex that emits light whose wavelength overlaps with the wavelength of an absorption band on the lowest energy side of the light-emitting substance. In this case, energy can be smoothly transferred and light emission can be efficiently obtained. The use of such a structure is preferred because the operating voltage can also be reduced.

[0139] It should be noted that at least one of the materials forming an exciplex can be a phosphorescent substance. In this case, the triplet excitation energy can be efficiently converted into the singlet excitation energy by reverse intersystem crossing.

[0140] To efficiently form an exciplex, a material with electron-transport properties is preferably combined with a material with hole-transport properties and a HOMO level higher than or equal to that of the material with electron-transport properties. Furthermore, the LUMO level of the material with hole-transport properties is preferably higher than or equal to that of the material with electron-transport properties. Note that the LUMO levels and HOMO levels of the materials can be calculated from the electrochemical properties (reduction potentials and oxidation potentials) of the materials measured by cyclic voltammetry (CV).

[0141] The formation of an exciplex can be confirmed, for example, by a phenomenon in which the emission spectrum of the mixed film in which the material having a hole-transport property and the material having an electron-transport property are mixed is shifted to the longer wavelength side than the emission spectrum of each of the materials (or the emission spectrum has a different peak on the longer wavelength side), which phenomenon is observed by comparing the emission spectra of the material having a hole-transport property, the material having an electron-transport property, and the mixed film of these materials. Alternatively, the formation of an exciplex can be confirmed by a difference in the transient response, such asA phenomenon in which the transient photoluminescence (PL) lifetime of the blend film exhibits longer-life components or a larger proportion of retardation components than that of either material can be confirmed, with the difference observed by comparing the transient PL of the hole-transporting material, the electron-transporting material, and the blend film of these materials. Transient PL can be reformulated as transient electroluminescence (EL). That is, the formation of an exciplex can also be confirmed by a difference in the transient response observed by comparing the transient EL of the hole-transporting material, the electron-transporting material, and the blend film of these materials.

[0142] The first electron-transport layer 114_1 and the second electron-transport layer 114_2 can be formed using any substance that has an electron-transport property and can transport more electrons than holes. The material with an electron-transport property preferably has an electron mobility of greater than or equal to 1 × 10 -7 cm 2 / Vs, preferably higher than or equal to 1 × 10 -6 cm 2 / Vs in the case where the square root of the electric field strength [V / cm] is 600. The above organic compound is preferably an organic compound having a π-electron-deficient heteroaromatic ring. The organic compound having a π-electron-deficient heteroaromatic ring is preferably one or more of an organic compound having a heteroaromatic ring with a polyazole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0143] As the organic compound having an electron-transport property that can be used in the first electron-transport layer 114_1 and the second electron-transport layer 114_2, any of the above-mentioned organic compounds that can be used as the organic compound having an electron-transport property serving as a host material in the first light-emitting layer 113_1 and the second light-emitting layer 113_2 can be used. Among the above organic compounds, the organic compound having a heteroaromatic ring with a diazine skeleton, the organic compound having a heteroaromatic ring with a pyridine skeleton, and the organic compound having a heteroaromatic ring with a triazine skeleton are particularly preferable due to their high reliability.In particular, the organic compound having a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and the organic compound having a heteroaromatic ring with a triazine skeleton have a high electron transport property to contribute to a reduction in operating voltage.

[0144] Note that the first electron-transport layer 114_1 may have a multilayer structure, but this is not necessary. When the first electron-transport layer 114_1 has a multilayer structure, the light-emitting device can have high current efficiency, low power consumption, and advantageous characteristics. When the first electron-transport layer 114_1 has a single-layer structure, the number of film formation chambers can be reduced, which is advantageous in terms of manufacturing costs.In the case of the multilayer structure, a layer included in the multilayer structure and positioned on the intermediate layer side preferably contains a third organic compound having a triazine skeleton to reduce the operating voltage and power consumption, and the layer preferably contains a fourth organic compound not having a triazine skeleton to appropriately control the electron transport from the intermediate layer.

[0145] The second electron transport layer 114_2 has the multilayer structure as described above. Fig. 1A illustrates a structure in which the second electron-transport layer 114_2 has the multilayer structure of the second electron-transport layer 114_2a and the second electron-transport layer 114_2b. The second electron-transport layer 114_2b is positioned between the second electron-transport layer 114_2a and the cathode. The second electron-transport layer 114_2b is preferably in contact with the second electrode 102 to improve its electron injection property, thereby reducing the operating voltage and power consumption.

[0146] Note that the second electron-transport layer 114_2b preferably contains the first organic compound having a triazine skeleton. It is preferable that the second electron-transport layer 114_2b be in contact with the second electrode 102 as described above, and it is more preferable that the second electron-transport layer 114_2b containing the first organic compound having a triazine skeleton be in contact with the second electrode 102 to improve its electron-injection property, thereby reducing the operating voltage and power consumption. The details of this have been described above and will not be repeated here.

[0147] Note that the first electron-transport layer 114_1 preferably contains the first organic compound having a triazine skeleton to reduce power consumption. Specifically, the organic compound having a triazine skeleton contained in the first electron-transport layer 114_1 and the first organic compound having a triazine skeleton contained in the second electron-transport layer 114_2b are preferably the same organic compound, which prevents the complication of a manufacturing facility and is also advantageous in terms of the cost of purchasing the source material. In the case where the first electron-transport layer 114_1 has a multilayer structure, the layer in contact with the intermediate layer 116 preferably contains the organic compound having a triazine skeleton.

[0148] In the case where the first electron-transport layer 114_1 has a multilayer structure and the layer in contact with the intermediate layer 116 contains an organic compound that does not have a triazine skeleton, the light-emitting device can have advantageous properties due to the easy control of charge carrier transport. The organic compound without a triazine skeleton is preferably an organic compound having a heteroaromatic ring with a pyridine skeleton or an organic compound having a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton. Alternatively, the organic compound without a triazine skeleton is preferably an organic compound having at least one of a pyrimidine skeleton, an imidazole skeleton, and an anthracene skeleton.For example, an organic compound having a pyrimidine skeleton and an anthracene skeleton or an organic compound having an imidazole skeleton and an anthracene skeleton is preferably used, in which case the charge carrier transport can be more easily controlled.

[0149] The intermediate layer 116 contains the second organic compound with a phenanthroline framework. As in Fig. 1A, the intermediate layer 116 preferably comprises a first layer 119 containing the second organic compound having a phenanthroline backbone. The intermediate layer 116 preferably comprises the second layer 117 containing the fifth organic compound having a hole-transport property and the substance having an acceptor property. The second layer 117 is positioned closer to the second electrode 102 than the first layer 119. The intermediate layer 116 may comprise a third layer 118 between the first layer 119 and the second layer 117.

[0150] The details of the first layer have been described above and will not be repeated here.

[0151] The first layer 119 may further contain an organic compound having an electron-transport property. As the organic compound having an electron-transport property, any of the above-mentioned organic compounds can also be used as the organic compound having an electron-transport property serving as a host material in the first light-emitting layer 113_1 and the second light-emitting layer 113_2. The organic compound having an electron-transport property is preferably an organic compound having two or more heteroaromatic rings bonded or condensed together and having a total of three or more heteroatoms. In this case, resistance to a photolithography process can be improved and an increase in operating voltage can be prevented.

[0152] Note that the first layer 119 may have a multilayer structure composed of a layer containing an organic compound and a layer containing a metal or metal compound, positioned closer to the cathode than the layer containing an organic compound, or it may be a mixed layer composed of an organic compound and a metal or metal compound. The first layer 119 is preferably a mixed layer because it requires fewer film formation chambers and lowers the manufacturing cost, and contributes to improving the stability of the light-emitting device.

[0153] In the case where the organic compound and the metal or metal compound are mixed, there is a tendency for the organic compound and the metal or metal compound to have substantially the same distribution when the first layer 119 is analyzed in the thickness direction. That is, when the organic compound is uniformly distributed, the metal or metal compound is also substantially uniformly distributed.In the case of the multilayer structure composed of the layer containing the organic compound and the layer containing the metal or metal compound, in some cases the metal or metal compound diffuses from the layer containing the metal or metal compound and is also detected in a different area than the layer, but it has a distribution different from that of the organic compound; therefore, the analysis results of diffusion and mixing can be distinguished from each other.

[0154] The second layer 117 preferably contains the fifth organic compound having a hole-transporting property. The second layer 117 preferably further contains a substance having an acceptor property, and the substance having an acceptor property is preferably an organic compound having an acceptor property with respect to the fifth organic compound.

[0155] In the case where the second layer 117 contains the fifth organic compound and the substance having an acceptor property with respect to the fifth organic compound, holes are generated by charge separation, and the holes are injected into the first light-emitting unit 501 on the cathode side via the fifth organic compound when a voltage is applied between the first electrode 101 and the second electrode 102. Therefore, the light-emitting device 130 of one embodiment of the present invention can have a low operating voltage.

[0156] As the fifth organic compound having a hole-transporting property, any of various organic compounds, such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and high-molecular-weight compounds (e.g., oligomers, dendrimers, and polymers), can be used. It should be noted that the fifth organic compound preferably has a hole mobility of 1 × 10 -6 cm 2 / Vs or higher. The fifth organic compound preferably has a condensed aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the condensed aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferred. As the π-electron-rich heteroaromatic ring, a condensed aromatic ring having at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferred; in particular, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further condensed with a carbazole ring or a dibenzothiophene ring is preferred.

[0157] Such an organic compound having a hole-transport property more preferably has any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. Specifically, an aromatic amine having a substituent with a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to nitrogen of an amine via an arylene group can be used. Note that the organic compound having a hole-transport property preferably has an N,N-bis(4-biphenyl)amino group to enable the fabrication of a light-emitting device with a long lifetime.

[0158] The above-described organic compound having a hole-transporting property may specifically be any of the organic compounds given as examples of the organic compound having a hole-transporting property that can be used in the hole-injection layer 111.

[0159] The substance having an acceptor property can be, for example, any of the substances given as examples of the organic compound having an acceptor property that can be used in the hole-injection layer 111. An organic compound having a halogen group and / or a cyano group is particularly preferable, and an organic compound having fluorine and / or a cyano group is more preferable. Note that more preferably, the total number of halogen groups (fluorine) and cyano groups of the organic compound is four or more. Examples of the organic compound having a halogen group and / or a cyano group include α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile] and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0160] It should be noted that the material having an acceptor property preferably has an electron acceptor property with respect to the fifth organic compound having a hole transport property. When the material having an acceptor property has an electron acceptor property with respect to the fifth organic compound, charge separation occurs, and the second layer 117 can serve as a charge generation layer and serves as an intermediate layer of the tandem light-emitting device. A signal is preferably observed by electron spin resonance in the second layer 117. For example, the density of spins attributable to a signal observed at a g-factor of approximately 2.00 is preferably greater than or equal to 1 × 10 17 Spins / cm 3 , preferably higher than or equal to 1 × 10 18 Spins / cm 3 , more preferably higher than or equal to 1 × 10 19 Spins / cm3.

[0161] The third layer 118 contains a substance having an electron transport property and has functions such as preventing the interaction between the first layer 119 and the second layer 117 and smoothly transmitting and receiving electrons therebetween to reduce the operating voltage, and reducing the interaction between the first layer 119 and the second layer 117 to improve reliability.

[0162] The LUMO level of the substance having an electron transport property contained in the third layer 118 is preferably located between the LUMO level of the substance having an acceptor property in the second layer 117 and the LUMO level of the organic compound in a layer (e.g., the first electron transport layer 114_1 in the first light-emitting unit 501 in Fig. 1A), which is in contact with the first layer 119 in the light-emitting unit on the anode side.

[0163] A specific energy level of the LUMO level of the substance having an electron-transport property used in the third layer 118 is preferably higher than or equal to -5.0 eV, more preferably higher than or equal to -5.0 eV and lower than or equal to -3.0 eV, even more preferably higher than or equal to -4.30 eV and lower than or equal to -3.00 eV, even more preferably higher than or equal to -4.30 eV and lower than or equal to -3.30 eV, in which case, an increase in the operating voltage can be prevented. Note that the substance having an electron-transport property used in the third layer 118 is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0164] Specific examples of the substance having an electron transport property used in the third layer 118 include perylenetetracarboxylic acid derivatives such as diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA), 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA-F6), 3,4,9,10-perylenetetracarboxylic acid diimide (abbreviation: PTCDI), and 3,4,9,10-perylenetetracarboxyl-bis-benzimidazole (abbreviation: PTCBI), (C 60 -I h )[5,6]Fullerene (abbreviation: C 60 ) and (C 70 -D 5h )[5,6]Fullerene (abbreviation: C 70). It is also possible to use a compound having a heterophane skeleton, which is a cyclophane skeleton with a hetero ring. For example, a phthalocyanine compound such as phthalocyanine (abbreviation: H2Pc) can be used as the compound. Alternatively, it is possible to use a metal phthalocyanine containing copper, zinc, cobalt, iron, chromium, nickel, or the like, or a derivative thereof, such as copper phthalocyanine (abbreviation: CuPc), zinc phthalocyanine (abbreviation: ZnPc), cobalt phthalocyanine (abbreviation: CoPc), iron phthalocyanine (abbreviation: FePc), tin phthalocyanine (abbreviation: SnPc), tin oxide phthalocyanine (abbreviation: SnOPc), titanium oxide phthalocyanine (abbreviation: TiOPc), or vanadium oxide phthalocyanine (abbreviation: VOPc). In particular, a phthalocyanine-based metal complex such as copper phthalocyanine or zinc phthalocyanine, or 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine is preferably used.

[0165] The thickness of the third layer 118 is preferably greater than or equal to 1 nm and less than or equal to 10 nm, more preferably greater than or equal to 2 nm and less than or equal to 5 nm.

[0166] Note that the second light-emitting unit 502 does not include a hole-injection layer because the second layer 117 in the intermediate layer 116 serves as a hole-injection layer; however, the second light-emitting unit 502 may include a hole-injection layer.

[0167] The second electrode 102 comprises the cathode. The second electrode 102 may have a multi-layer structure, in which case a layer in contact with the organic compound layer 103 serves as the cathode. The cathode is preferably formed, for example, using a metal, an alloy, an electrically conductive compound, or a mixture thereof, each having a low work function (in particular, lower than or equal to 3.8 eV). Specific examples of such a cathode material include elements belonging to Group 1 and Group 2 of the Periodic Table, such as alkali metals (e.g., lithium (Li) or cesium (Cs)), magnesium (Mg), calcium (Ca), and strontium (Sr), alloys containing any of these elements (e.g., MgAg and AlLi), rare earth metals, such as B. Europium (Eu) and Ytterbium (Yb), and alloys containing any of these rare earth metals.Specific examples include alkali metals, alkaline earth metals, rare earth elements, compounds thereof, and complexes thereof, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), 8-hydroxyquinolinato lithium (abbreviation: Liq), and ytterbium (Yb), and electrides. Examples of the electrides include substances in which electrons are added at a high concentration to calcium oxide-alumina. Note that a mixture of two or more of these materials can be used as the cathode material. In the case where the second electrode 102 has a multilayer structure, a material with high conductivity can be used for the layer(s) other than the cathode, regardless of the work function.

[0168] Note that the second electron-transport layer 114_2 is preferably in contact with the second electrode 102. When the second electron-transport layer 114_2 is in contact with the second electrode 102, the light-emitting device can have excellent electron injection and electron transport characteristics, a low operating voltage, and low power consumption.

[0169] When the second electrode 102 is formed using a material that transmits visible light, the light-emitting device can emit light from the second electrode 102 side.

[0170] Films of these conductive materials can be formed by a dry process such as a vacuum evaporation method or a sputtering method, an inkjet method, a spin-coating method, or the like. Alternatively, a wet process using a sol-gel method or a wet process using a paste of a metal material can be used.

[0171] The organic compound layer 103 can be formed by any of various methods including a dry process and a wet process. For example, a vacuum evaporation method, a gravure printing method, an offset printing method, a screen printing method, an inkjet method, a spin coating method, or the like can be used.

[0172] Different film formation methods can be used to form the electrodes or layers described above.

[0173] Fig. 2 illustrates two adjacent light-emitting devices (a light-emitting device 130a and a light-emitting device 130b) included in a display device of an embodiment of the present invention.

[0174] The light-emitting device 130a includes an organic compound layer 103a between a first electrode 101a and the second electrode 102 over an insulating layer 175. The organic compound layer 103a has a structure in which a first light-emitting unit 501a and a second light-emitting unit 502a are stacked with an intermediate layer 116a therebetween. Although Fig. 2 illustrates an example in which the two light-emitting units are stacked, three or more light-emitting units may be stacked. The first light-emitting unit 501a includes a hole-injection layer 111a, a first hole-transport layer 112a_1, a first light-emitting layer 113a_1, and a first electron-transport layer 114a_1 (a first electron-transport layer 114a_1a and a first electron-transport layer 114a_1b). The first electron-transport layer 114a_1 is illustrated as having a multilayer structure; however, it may also have a single-layer structure. The intermediate layer 116a includes a second layer 117a, a third layer 118a, and a first layer 119a. The third layer 118a may be present or absent.The second light-emitting unit 502a includes a second hole transport layer 112a_2, a second light-emitting layer 113a_2, and a second electron transport layer 114a_2 (a second electron transport layer 114a_2a and a second electron transport layer 114a_2b).

[0175] The light-emitting device 130b includes an organic compound layer 103b between a first electrode 101b and the second electrode 102 over the insulating layer 175. The organic compound layer 103b has a structure in which a first light-emitting unit 501b and a second light-emitting unit 502b are stacked with an intermediate layer 116b therebetween. Although Fig. 2 illustrates an example in which the two light-emitting units are stacked, three or more light-emitting units may be stacked. The first light-emitting unit 501b includes a hole-injection layer 111b, a first hole-transport layer 112b_1, a first light-emitting layer 113b_1, and a first electron-transport layer 114b_1 (a first electron-transport layer 114b_1a and a first electron-transport layer 114b_1b). The first electron-transport layer 114b_1 is illustrated as having a multi-layer structure; however, it may also have a single-layer structure. The intermediate layer 116b includes a second layer 117b, a third layer 118b, and a first layer 119b. The third layer 118b may be present or absent.The second light-emitting unit 502b includes a second hole transport layer 112b_2, a second light-emitting layer 113b_2, and a second electron transport layer 114b_2 (a second electron transport layer 114b_2a and a second electron transport layer 114b_2b).

[0176] The second electron-transport layer 114a_2 and the second electron-transport layer 114b_2 may each have a multilayer structure. The second electron-transport layer 114a_2b and the second electron-transport layer 114b_2b, which are the layers located on the cathode side in the multilayer structures, preferably contain the first organic compound having a triazine skeleton. The first layer 119a and the first layer 119b each contain the second organic compound having a phenanthroline skeleton.

[0177] The first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 preferably emit light of similar colors. The emission center substance contained in the first light-emitting layer 113a_1 and the emission center substance contained in the second light-emitting layer 113a_2 are preferably compounds whose emission spectra have a difference in the maximum peak wavelength of less than or equal to 30 nm, more preferably less than or equal to 20 nm, even more preferably less than or equal to 10 nm. More preferably, the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 contain the same emission center substance. The first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 preferably emit light of similar colors.The emission center substance contained in the first light-emitting layer 113b_1 and the emission center substance contained in the second light-emitting layer 113b_2 are preferably compounds whose emission spectra have a maximum peak wavelength difference of less than or equal to 30 nm, more preferably less than or equal to 20 nm, and even more preferably less than or equal to 10 nm. More preferably, the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 contain the same emission center substance.

[0178] It is preferable that the first light-emitting layer 113a_1 and the first light-emitting layer 113b_1 are separated from each other, and the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2 are separated from each other. It is preferable that the first light-emitting layer 113a_1 and the first light-emitting layer 113b_1 are different light-emitting layers from each other, and that the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2 are different light-emitting layers from each other. It is preferable that the emission color(s) of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are different from the emission color(s) of the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2.Preferably, the emission center substance contained in the first light-emitting layer 113a_1 and the emission center substance contained in the first light-emitting layer 113b_1 are different substances from each other, and the emission center substance contained in the second light-emitting layer 113a_2 and the emission center substance contained in the second light-emitting layer 113b_2 are different substances from each other.

[0179] In the case where the emission center substances contained in the first light-emitting layers 113a_1 and 113b_1 are different substances from each other and the emission center substances contained in the second light-emitting layers 113a_2 and 113b_2 are different substances from each other (e.g.in the case where the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are blue fluorescent layers and the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 are green phosphorescent layers, in the case where the first light-emitting layers 113a_1 and 113a_2 are blue fluorescent layers and the first light-emitting layers 113b_1 and 113b_2 are red phosphorescent layers, or in the case where the first light-emitting layers 113a_1 and 113a_2 are green phosphorescent layers and the first light-emitting layers 113b_1 and 113b_2 are red phosphorescent layers), the light-emitting layers of the light-emitting devices 130a and 130b different charge carrier equilibria.Therefore, to improve the performance of each of the light-emitting devices 130a and 130b, it is usually necessary to select and use a suitable intermediate layer and a suitable electron-transport layer for each light-emitting device. However, even if the second electron-transport layers 114a_2 and 114b_2 have the same structure, the use of the first organic compound having a triazine skeleton in the second electron-transport layers 114a_2 and 114b_2 and the use of the second organic compound having a phenanthroline skeleton in the first layers 119a and 119b can improve the performance of each of the light-emitting devices 130a and 130b. That is, both productivity and performance can be improved. Note that the first layers 119a and 119b can have the same structure.

[0180] It should be noted that each of the pairs of the hole injection layers 111a and 111b, the first hole transport layers 112a_1 and 112b_1, the first electron transport layers 114a_1 and 114b_1 (the first electron transport layers 114a_1a and 114b_1a and the first electron transport layers 114a_1b and 114b_1b), the intermediate layers 116a and 116b (the second layers 117a and 117b, the third layers 118a and 118b and the first layers 119a and 119b), the second hole transport layers 112a_2 and 112b_2 and the second electron transport layers 114a_2 and 114b_2 (the second electron transport layers 114a_2a and 114b_2a and the second Electron transport layers 114a_2b and 114b_2b) may be a continuous layer or may be separate layers that are independent of each other between the light-emitting device 130a and the light-emitting device 130b.When these layers are continuous layers, the light-emitting devices can be manufactured with high productivity and low cost. When the layers between the light-emitting devices are separate layers, the layers can be formed using materials suitable for their emission colors, thereby enabling the light-emitting devices or a display device to exhibit advantageous properties. In particular, the second electron-transport layer 114a_2 and the second electron-transport layer 114b_2 are preferably a continuous layer, in which case both the light-emitting device 130a and the light-emitting device 130b can exhibit advantageous properties.

[0181] The second electron-transport layer 114a_2b and the second electron-transport layer 114b_2b being a continuous layer means that these layers are formed from the same material. In other words, when the second electron-transport layer 114a_2b and the second electron-transport layer 114b_2b are formed from the same material, both the light-emitting device 130a and the light-emitting device 130b can have advantageous properties. The second electron-transport layer 114a_2b and the second electron-transport layer 114b_2b preferably have similar structures, and even more preferably have the same structure. In the case where the emission center substances contained in the first light-emitting layers 113a_1 and 113b_1 are different substances from each other, and the emission center substances contained in the second light-emitting layers 113a_2 and 113b_2 are different,are different substances from each other (e.g., in the case where the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are blue fluorescent layers and the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 are green phosphorescent layers, in the case where the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are blue fluorescent layers and the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 are red phosphorescent layers, or in the case where the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are green phosphorescent layers and the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2 red phosphorescent layers),The light-emitting layers of the light-emitting devices 130a and 130b have different charge carrier balances. Therefore, in order to improve the performance of each of the light-emitting devices 130a and 130b, it is usually necessary to select and use a suitable intermediate layer and a suitable electron-transport layer for each light-emitting device. However, even if the second electron-transport layers 114a_2b and 114b_2b are a continuous layer, the use of the first organic compound having a triazine skeleton in the second electron-transport layers 114a_2b and 114b_2b, which are the layers located on the cathode side in the electron-transport layers with the multilayer structures,and the use of the second organic compound having a phenanthroline framework in the first layers 119a and 119b can improve the performance of each of the light-emitting devices 130a and 130b. That is, both productivity and performance can be improved. Note that the first layers 119a and 119b can have the same structure.

[0182] Note that a continuous layer is a so-called common layer formed across the light-emitting devices 130a and 130b.

[0183] Fig. 3 is a modification example of Fig. 2. The light-emitting device 130a and a light-emitting device 130b1 emit light of different colors and therefore have different optical path lengths between the electrodes. Light emitted from the light-emitting devices can be amplified using the microcavity. In the light-emitting device 130b1, the distance between the electrodes can be adjusted by making light-emitting layers, such as a light-emitting layer 113b_11 and a light-emitting layer 113b_21, thicker. Alternatively, the optical path length can be changed by making a functional layer, such as a hole-transport layer 112b_21, thicker or adding it.

[0184] Fig. 4 illustrates three adjacent light-emitting devices (the light-emitting device 130a, the light-emitting device 130b1, and a light-emitting device 130c) included in a display device of one embodiment of the present invention.

[0185] The light-emitting device 130c includes an organic compound layer 103c between a first electrode 101c and the second electrode 102 over the insulating layer 175. The organic compound layer 103c has a structure in which a first light-emitting unit 501c and a second light-emitting unit 502c are stacked with an intermediate layer 116c therebetween. Although Fig. 4 illustrates an example in which the two light-emitting units are stacked, three or more light-emitting units may be stacked. The first light-emitting unit 501c includes a hole-injection layer 111c, a first hole-transport layer 112c_1, a first light-emitting layer 113c_1, and a first electron-transport layer 114c_1 (a first electron-transport layer 114c_1a and a first electron-transport layer 114c_1b). Note that the first electron-transport layer 114c_1 may have a single-layer structure. The intermediate layer 116c includes a second layer 117c, a third layer 118c, and a first layer 119c. The third layer 118c may be present or absent.The second light-emitting unit 502c includes a second hole transport layer 112c_2, a second light-emitting layer 113c_2, and a second electron transport layer 114c_2 (a second electron transport layer 114c_2a and a second electron transport layer 114c_2b).

[0186] Here, it is assumed that the light-emitting device 130c emits light whose wavelength is shorter than that of the light from the light-emitting devices 130a and 130b1. The distance between the electrodes in the light-emitting device 130c is adjusted by the thicknesses of the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2, which are smaller than those of the light-emitting layers in the other two light-emitting devices.

[0187] The second electron-transport layer 114c_2 has a multilayer structure. The second electron-transport layer 114c_2b, which is the layer located on the cathode side in the multilayer structure, preferably contains the first organic compound having a triazine skeleton. The first layer 119c contains the second organic compound having a phenanthroline skeleton.

[0188] The first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 preferably emit light of similar colors. The emission center substance contained in the first light-emitting layer 113c_1 and the emission center substance contained in the second light-emitting layer 113c_2 are preferably compounds whose emission spectra have a difference in the maximum peak wavelength of less than or equal to 30 nm, more preferably less than or equal to 20 nm, and even more preferably less than or equal to 10 nm. More preferably, the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2 contain the same emission center substance.

[0189] It is preferable that the first light-emitting layer 113a_1 and the first light-emitting layer 113c_1 are separated from each other, and the second light-emitting layer 113a_2 and the second light-emitting layer 113c_2 are separated from each other. Preferably, the emission color(s) of the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 are different from the emission color(s) of the first light-emitting layer 113c_1 and the second light-emitting layer 113c_2.Preferably, the emission center substance contained in the first light-emitting layer 113a_1 and the emission center substance contained in the first light-emitting layer 113c_1 are different substances from each other, and the emission center substance contained in the second light-emitting layer 113a_2 and the emission center substance contained in the second light-emitting layer 113c_2 are different substances from each other.

[0190] Note that each of the pairs of hole-injection layers 111a and 111c, first hole-transport layers 112a_1 and 112c_1, first electron-transport layers 114a_1 and 114c_1, intermediate layers 116a and 116c (second layers 117a and 117c, third layers 118a and 118c, and first layers 119a and 119c), and second hole-transport layers 112a_2 and 112c_2 in this example are independent, separate layers between light-emitting device 130a and light-emitting device 130c, and second electron-transport layers 114a_2 and 114c_2 are a continuous layer in this example. In this way, a light-emitting device may include both continuous and separate layers. This allows the light-emitting device or display device to balance productivity and properties.In particular, the second electron transport layer 114a_2b and the second electron transport layer 114c_2b are preferably a continuous layer, in which case both the light-emitting device 130a and the light-emitting device 130c may have advantageous properties.

[0191] In the case where light-emitting devices representing three colors are formed, for example, from two light-emitting devices containing fluorescent emission center substances and one light-emitting device containing a phosphorescent emission center substance, the light-emitting devices containing the fluorescent emission center substances preferably comprise a continuous charge transport layer, and the light-emitting device containing the phosphorescent emission center substance preferably comprises a charge transport layer separate from that in the light-emitting devices representing the other emission colors.Alternatively, in the case where light-emitting devices representing three colors are formed of two light-emitting devices containing phosphorescent emission center substances and one light-emitting device containing a fluorescent emission center substance, the light-emitting devices containing the phosphorescent emission center substances preferably comprise a continuous carrier transport layer, and the light-emitting device containing the fluorescent emission center substance preferably comprises a carrier transport layer separate from that in the light-emitting devices representing the other emission colors.

[0192] The light-emitting device of one embodiment of the present invention having such a structure can exhibit high power efficiency, low energy loss, and advantageous characteristics. The display device of one embodiment of the present invention including such a light-emitting device can achieve low power consumption, high reliability, high luminance display, and high visibility. This embodiment can be freely combined with any of the other embodiments. (Embodiment 2)

[0193] In this embodiment, the display device manufactured using the light-emitting device described in Embodiment 1 is described by Fig. 5A and Fig. 5B. It should be noted that Fig. 5A is a plan view of the display device and Fig. 5B is a cross-sectional view along lines AB and CD in Fig. 5A. This display device includes a driving circuit section (a source line driving circuit) 601, a pixel section 602, and a driving circuit section (a gate line driving circuit) 603, which control the light emission of a light-emitting device and are shown with dashed lines. Reference numeral 604 denotes a sealing substrate; 605, a sealing material; and 607, a space surrounded by the sealing material 605.

[0194] Reference numeral 608 denotes a line for transmitting signals input to the source line driver circuit 601 and the gate line driver circuit 603, and for receiving signals such as a video signal, a clock signal, a start signal, and a reset signal from a flexible printed circuit (FPC) 609 serving as an external input terminal. Although only the FPC is illustrated here, a printed wiring board (PWB) may be attached to the FPC. The display device in this specification includes within its category not only the display device itself but also the display device provided with the FPC or the PWB.

[0195] Next, a cross-sectional structure is created using Fig. 5B. The driver circuit portions and the pixel portion are formed over an element substrate 610; Fig. 5B illustrates the source line driver circuit 601, which is a driver circuit portion, and a pixel of the pixel portion 602.

[0196] The element substrate 610 may be a substrate formed of glass, quartz, an organic resin, a metal, an alloy, or a semiconductor, or a plastic substrate formed of fiber reinforced plastic (FRP), polyvinyl fluoride (PVF), polyester, or an acrylic resin.

[0197] The structure of the transistors used in the pixels and the driving circuits is not particularly limited. For example, inverted-staggered transistors or staggered transistors may be used. Further, top-gate transistors or bottom-gate transistors may be used. A semiconductor material used for the transistors is not particularly limited, and for example, silicon, germanium, silicon carbide, gallium nitride, or the like may be used. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In-Ga-Zn-based metal oxide, may also be used.

[0198] There is no particular limitation on the crystallinity of a semiconductor material used for transistors, and either an amorphous semiconductor or a semiconductor having crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single-crystal semiconductor, or a semiconductor partially comprising crystal regions) can be used. Preferably, a semiconductor having crystallinity is used, in which case, deterioration of transistor characteristics can be suppressed.

[0199] Here, an oxide semiconductor is preferably used for semiconductor devices such as transistors provided in pixels and driver circuits, and transistors used for touch sensors and the like described later. Specifically, an oxide semiconductor having a wider band gap than silicon is preferably used. By using an oxide semiconductor having a wider band gap than silicon, the off-state current of the transistors can be reduced.

[0200] The oxide semiconductor preferably contains at least one of indium (In) and zinc (Zn). The oxide semiconductor more preferably contains an oxide represented by an In-M-Zn-based oxide (M represents a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0201] As the semiconductor layer, it is particularly preferable to use an oxide semiconductor film which comprises a plurality of crystal parts whose c-axes are oriented perpendicular to a surface on which the semiconductor layer is formed or the top surface of the semiconductor layer, and in which the adjacent crystal parts do not have a grain boundary.

[0202] The use of such materials for the semiconductor layer makes it possible to provide a transistor with high reliability in which changes in electrical properties are suppressed.

[0203] Due to the transistor's low off-state current, a charge accumulated in a capacitor via a transistor including the above-described semiconductor layer can be retained for a long time. When such a transistor is used in a pixel, the operation of a drive circuit can be interrupted while maintaining a gray level of an image in each display area. As a result, an electronic device with very low power consumption can be obtained.

[0204] For stable characteristics of the transistor and the like, a base film is preferably provided. The base film can be formed to have a single-layer structure or a multi-layer 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 base film can be formed by a sputtering method, a chemical vapor deposition (CVD) method (e.g., a plasma CVD method, a thermal CVD method, or a metal organic CVD (MOCVD) method), an atomic layer deposition (ALD) method, a coating method, a printing method, or the like. Note that the base film is not necessarily provided.

[0205] Note that an FET 623 is illustrated as a transistor formed in the driver circuit section 601. Furthermore, the driver circuit may be formed using any of various circuits, such as a CMOS circuit, a PMOS circuit, or an NMOS circuit. Although a driver-integrated type in which the driver circuit is formed over the substrate is described in this embodiment, the driver circuit is not necessarily formed over the substrate, and the driver circuit may be formed externally.

[0206] The pixel section 602 includes a plurality of pixels, each including a switching FET 611, a current controlling FET 612, and a first electrode 613 electrically connected to a drain of the current controlling FET 612. An embodiment of the present invention is not limited to the structure, and the pixel section 602 may include three or more FETs and a capacitor in combination.

[0207] Note that an insulator 614 is formed to cover an end portion of the first electrode 613. Here, the insulator 614 can be formed using a positive photosensitive acrylic resin film.

[0208] To improve the coverage with an organic compound layer or the like to be formed later, the insulator 614 is formed to have a curved surface with a curvature at its upper or lower end portion. For example, in the case where a positive photosensitive acrylic resin is used as the material of the insulator 614, it is preferable that only the upper end portion of the insulator 614 has a curved surface with a radius of curvature (0.2 μm to 3 μm). Either a negative photosensitive resin or a positive photosensitive resin can be used for the insulator 614.

[0209] An organic compound layer 616 and a second electrode 617 are formed over the first electrode 613. Here, as the material used for the first electrode 613 serving as an anode, a material with a high work function is preferably used. For example, a single-layer film of an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% to 20 wt% of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, or the like; a stacked film of a titanium nitride film and a film containing aluminum as its main component; a stacked film of three layers of a titanium nitride film, a film containing aluminum as its main component, and a titanium nitride film; or the like can be used.The multilayer structure enables low conduction resistance, advantageous ohmic contact and an anode function.

[0210] The organic compound layer 616 is formed by any of various methods, such as an evaporation method using an evaporation mask, an inkjet method, and a spin coating method. The organic compound layer 616 has the structure described in Embodiment 1. As another material contained in the organic compound layer 616, a low-molecular compound or a high-molecular compound (including an oligomer or a dendrimer) can be used.

[0211] As the material used for the second electrode 617 formed over the organic compound layer 616 and serving as a cathode, a low work function material (e.g., Al, Mg, Li, and Ca, or an alloy or compound thereof, such as MgAg, MgIn, and AlLi) is preferably used. In the case where light generated in the organic compound layer 616 is transmitted through the second electrode 617, a stacked arrangement of a thin metal 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)) is preferably used for the second electrode 617.

[0212] Note that the light-emitting device is formed including the first electrode 613, the organic compound layer 616, and the second electrode 617. This light-emitting device is the light-emitting device described in Embodiment 1. In the display device of this embodiment, the pixel portion including a plurality of light-emitting devices may include both the light-emitting device described in Embodiment 1 and a light-emitting device having a different structure.

[0213] The sealing substrate 604 is attached to the element substrate 610 with the sealing material 605, so that a light-emitting device 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. The space 607 may be filled with a filler, or may be filled with an inert gas (such as nitrogen or argon) or the sealing material. The structure of the sealing substrate in which a recessed portion is formed and a desiccant is provided is preferable because deterioration due to the influence of moisture can be prevented.

[0214] An epoxy-based resin or a glass frit is preferably used for the sealing material 605. Such a material should preferably allow as little moisture or oxygen permeation as possible. A glass substrate, a quartz substrate, or a plastic substrate made of fiber-reinforced plastic (FRP), polyvinyl fluoride (PVF), polyester, and acrylic resin can be used as the sealing substrate 604.

[0215] Although in Fig. 5B, a protective film may be provided over the second electrode 617. An organic resin film or an inorganic insulating film may be formed as the protective film. The protective film may be formed to cover an exposed portion of the sealing material 605. The protective film may be provided to cover surfaces and side surfaces of the pair of substrates and exposed side surfaces of a sealing layer, an insulating layer, and the like.

[0216] The protective film can be formed using a material that is less likely to allow contaminants such as water to pass through easily. Thus, the diffusion of contaminants such as water from the outside to the inside can be effectively suppressed.

[0217] As the material for the protective film, an oxide, a nitride, a fluoride, a sulfide, a ternary compound, a metal, a polymer or the like can be used. For example, the material may contain alumina, 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, a nitride containing titanium and aluminum, an oxide containing titanium and aluminum, an oxide containing aluminum and zinc, a sulfide containing manganese and zinc, a sulfide containing cerium and strontium, an oxide containing erbium and aluminum, an oxide containing yttrium and zirconium, or the like.

[0218] The protective film is preferably formed using a film formation method with favorable step coverage. One such method is an ALD method. A material that can be deposited by an ALD method is preferably used for the protective film. A dense protective film with reduced defects, such as cracks or pinholes, or with a uniform thickness can be formed by an ALD method. Furthermore, damage to a process element during formation of the protective film can be reduced.

[0219] Using an ALD process, a uniform protective film with few defects can be formed, for example, even on a surface with a complex irregular shape or on the top, side, and bottom surfaces of a touchscreen.

[0220] As described above, the display device manufactured by using the light-emitting device described in Embodiment 1 can be obtained.

[0221] The display device in this embodiment is manufactured using the light-emitting device described in Embodiment 1 and can therefore have advantageous characteristics. In particular, since the light-emitting device described in Embodiment 1 has high emission efficiency, the display device can achieve low power consumption. Since the light-emitting device described in Embodiment 1 has high reliability, the display device can be highly reliable. In addition, since the light-emitting device described in Embodiment 1 can have favorable chromaticity and high color purity, the display device can achieve high display quality.

[0222] This embodiment can be freely combined with one of the other embodiments. (Embodiment 3)

[0223] As in Fig. 6A and Fig. 6B, a plurality of light-emitting devices 130 are formed over an insulating layer 175 to form a display device. In this embodiment, the display device of another embodiment of the present invention will be described in detail.

[0224] A display device 100 includes a pixel portion 177 in which a plurality of pixels 178 are arranged in a matrix. Pixel 178 includes a subpixel 110R, a subpixel 110G, and a subpixel 110B.

[0225] For example, in this specification and the like, the description common to subpixels 110R, 110G, and 110B is sometimes described using the collective term "subpixel 110." Regarding other components that are distinguishable from each other using alphabetic letters, things common to the components are sometimes described using reference numerals without the alphabetic letters.

[0226] Subpixel 110R emits red light, subpixel 110G emits green light, and subpixel 110B emits blue light. Therefore, an image can be displayed on pixel portion 177. Note that, in this embodiment, three colors of red (R), green (G), and blue (B) are given as examples of colors of light emitted by the subpixels, but subpixels of a different combination of colors may be used. The number of subpixels is not limited to three and may be four or more. Examples of four subpixels include subpixels emitting light of four colors of R, G, B, and white (W), subpixels emitting light of four colors of R, G, B, and Y, and four subpixels emitting light of R, G, and B and infrared (IR) light.

[0227] In this specification and the like, the row direction and column direction are sometimes referred to as the X direction and the Y direction, respectively. The X direction and the Y direction intersect each other and are perpendicular to each other, for example.

[0228] Fig. 6A illustrates an example in which subpixels of different colors are arranged in the X direction and subpixels of the same color are arranged in the Y direction. Note that subpixels of different colors may be arranged in the Y direction, and subpixels of the same color may be arranged in the X direction.

[0229] A connecting portion 140 is provided outside the pixel portion 177, and a region 141 may also be provided. In the case where the region 141 is provided, the region 141 is provided between the pixel portion 177 and the connecting portion 140. In the case where the region 141 is provided, an organic connecting layer is provided in the region 141. A conductive layer 151C is provided in the connecting portion 140.

[0230] Although Fig. 6A illustrates an example in which the region 141 and the connecting portion 140 are positioned on the right side of the pixel portion 177, the positions of the region 141 and the connecting portion 140 are not particularly limited. The number of regions 141 and the number of connecting portions 140 may each be one or more.

[0231] Fig. 6B is an example of a cross-sectional view along the dotted line A1-A2 in Fig. 6A. As in Fig. 6B, the display device 100 includes an insulating layer 171, a conductive layer 172 over the insulating layer 171, an insulating layer 173 over the insulating layer 171 and the conductive layer 172, an insulating layer 174 over the insulating layer 173, and the insulating layer 175 over the insulating layer 174. The insulating layer 171 is provided over a substrate (not shown). An opening reaching the conductive layer 172 is provided in the insulating layers 175, 174, and 173, and a terminal plug 176 is provided to fill the opening.

[0232] In the pixel portion 177, the light-emitting device 130 is provided over the insulating layer 175 and the terminal plug 176. A protective layer 131 is provided to cover the light-emitting device 130. A substrate 120 is bonded to the protective layer 131 by a resin layer 122. An inorganic insulating layer 125 and an insulating layer 127 over the inorganic insulating layer 125 are preferably provided between the adjacent light-emitting devices 130.

[0233] Although Fig. 6B illustrates cross sections of a plurality of the inorganic insulating layers 125 and a plurality of the insulating layers 127, the inorganic insulating layers 125 are preferably bonded to each other and the insulating layers 127 are preferably bonded to each other when the display device 100 is viewed from above.

[0234] In Fig. 6B, a light-emitting device 130R, a light-emitting device 130G, and a light-emitting device 130B are each depicted as light-emitting device 130. The light-emitting devices 130R, 130G, and 130B emit light of different colors. For example, the light-emitting device 130R may emit red light, the light-emitting device 130G may emit green light, and the light-emitting device 130B may emit blue light. Alternatively, the light-emitting device 130R, the light-emitting device 130G, or the light-emitting device 130B may emit visible light of another color or infrared light.

[0235] The display device of one embodiment of the present invention may, for example, be a top-emission display device in which light is emitted in the direction opposite to a substrate over which light-emitting devices are formed. Note that the display device of one embodiment of the present invention may be a bottom-emission type.

[0236] The light-emitting device 130R includes a first electrode 101R (pixel electrode) including a conductive layer 151R and a conductive layer 152R, an organic interconnect layer 103R over the first electrode, the common layer 104 over the organic interconnect layer 103R, and the second electrode 102 (common electrode) over the common layer 104. Although the common layer 104 is not necessarily provided, the common layer 104 is preferably provided to reduce damage to the organic interconnect layer 103R during processing.

[0237] The light-emitting device 130G includes a first electrode 101G (pixel electrode) including a conductive layer 151G and a conductive layer 152G, an organic interconnect layer 103G over the first electrode, the common layer 104 over the organic interconnect layer 103G, and the second electrode 102 (common electrode) over the common layer 104. Although the common layer 104 is not necessarily provided, the common layer 104 is preferably provided to reduce damage to the organic interconnect layer 103G during processing.

[0238] The light-emitting device 130B has a structure described in Embodiment 1. The light-emitting device 130B includes a first electrode 101B (pixel electrode) including a conductive layer 151B and a conductive layer 152B, an organic interconnection layer 103B over the first electrode, the common layer 104 over the organic interconnection layer 103B, and the second electrode 102 (common electrode) over the common layer 104. Although the common layer 104 is not necessarily provided, the common layer 104 is preferably provided to reduce damage to the organic interconnection layer 103B during processing.Furthermore, in the case where the common layer 104 is provided, a layer arrangement of the organic compound layer 103B and the common layer 104 corresponds to the organic compound layer 103 described in Embodiment 1; in the case where the common layer 104 is not provided, the organic compound layer 103B corresponds to the organic compound layer 103 described in Embodiment 1.

[0239] Note that the common layer 104 is preferably an electron-transport layer. In the case where the common layer 104 is an electron-transport layer, it is preferable that the electron-transport layer has a multilayer structure, and it is more preferable that, among the stacked layers, a layer on the second electrode side is the common layer 104 and a layer on the light-emitting layer side is the organic compound layer 103.

[0240] The light-emitting devices 130R and 130G are manufactured by a photolithography process.

[0241] In the light-emitting device 130, one of the pixel electrode and the common electrode serves as the anode, and the other serves as the cathode. The following description assumes that the pixel electrode serves as the anode and the common electrode serves as the cathode, unless otherwise specified.

[0242] The organic compound layers 103R, 103G, and 103B are island-shaped layers that are independent of each other based on a light-emitting device or based on an emission color. By providing the island-shaped organic compound layer 103 in each of the light-emitting devices 130, the leakage current between the adjacent light-emitting devices 130 can be prevented even in a high-resolution display device. This can prevent crosstalk, so that a display device with very high contrast can be obtained. In particular, a display device with high current efficiency at low luminance can be obtained.

[0243] The island-shaped organic compound layer 103 is formed by forming an organic compound film and processing the organic compound film by a photolithography method.

[0244] The organic compound layer 103 is preferably provided to cover the top and side surfaces of the first electrode (pixel electrode) of the light-emitting device 130. In this case, the aperture ratio of the display device 100 can be slightly increased compared to the structure in which an end portion of the organic compound layer 103 is located further inside than an end portion of the pixel electrode. By covering the side surface of the pixel electrode of the light-emitting device 130 with the organic compound layer 103, the pixel electrode can be prevented from being in contact with the second electrode 102; thus, a short circuit of the light-emitting device 130 can be prevented.

[0245] In the display device of one embodiment of the present invention, the first electrode (pixel electrode) of the light-emitting device preferably has a multilayer structure. For example, in the Fig. 6B, the first electrode of the light-emitting device 130 comprises a layer arrangement of the conductive layer 151 (the conductive layer 151R, the conductive layer 151G, and the conductive layer 151B) and the conductive layer 152 (the conductive layer 152R, the conductive layer 152G, and the conductive layer 152B).

[0246] A metal material can be used, for example, for the conductive layer 151. In particular, it is possible to use, for example, a metal such as aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), or neodymium (Nd), or an alloy containing a suitable combination of any of these metals.

[0247] For the conductive layer 152, an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon may be used. For example, a conductive oxide containing one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, indium zinc oxide containing silicon, and the like is preferably used. In particular, an indium tin oxide containing silicon can be suitably used for the conductive layer 152 because it has, for example, a work function higher than or equal to 4.0 eV.

[0248] The conductive layer 151 and the conductive layer 152 may each be a stack of a plurality of layers containing different materials. In this case, the conductive layer 151 may include a layer formed using a material that can be used for the conductive layer 152, such as a conductive oxide. Furthermore, the conductive layer 152 may include a layer formed using a material that can be used for the conductive layer 151, such as a metal material. In the case where the conductive layer 151 is a stack of two or more layers, for example, a layer in contact with the conductive layer 152 may be formed using a material that can be used for the conductive layer 152.

[0249] Next, an exemplary method for manufacturing the display device 100 having the Fig. 6A shown structure using Fig. 7A to Fig. 7E, Fig. 8A and Fig. 8B, Fig. 9A to Fig. 9D, Fig. 10A to Fig. 10C, Fig. 11A to Fig. 11C and Fig. 12A to Fig. 12C described. [Example 1 of the manufacturing process]

[0250] Thin films included in the display device (e.g., insulating films, semiconductor films, and conductive films) can be formed by a sputtering method, a CVD method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an ALD method, or the like.

[0251] Thin films included in the display device (e.g., insulating films, semiconductor films, and conductive films) can also be formed by a wet process such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor blade coating, gap coating, roll coating, curtain coating, or doctor blade coating.

[0252] Thin films included in the display device can be processed, for example, by a photolithography process.

[0253] As the light used for exposure in the photolithography process, for example, i-line light (wavelength: 365 nm), g-line light (wavelength: 436 nm), h-line light (wavelength: 405 nm), or light in which the i-line, g-line, and h-line are mixed can be used. Alternatively, ultraviolet rays, KrF laser light, ArF laser light, or the like can be used. Exposure can be performed by a liquid immersion exposure technique. Extreme ultraviolet (EUV) light or X-rays can also be used as the light for exposure. Furthermore, an electron beam can also be used instead of the light used for exposure.

[0254] To etch thin films, a dry etching method, a wet etching method, a sandblasting method, or the like can be used.

[0255] First, as in Fig. 7A, the insulating layer 171 is formed over a substrate (not shown). Next, the conductive layer 172 and a conductive layer 179 are formed over the insulating layer 171, and the insulating layer 173 is formed over the insulating layer 171 so as to cover the conductive layer 172 and the conductive layer 179. Then, the insulating layer 174 is formed over the insulating layer 173, and the insulating layer 175 is formed over the insulating layer 174.

[0256] As the substrate, a substrate having heat resistance high enough to withstand at least one subsequent heat treatment can be used. For example, it is possible to use a glass substrate; a quartz substrate; a sapphire substrate; a ceramic substrate; an organic resin substrate; or a semiconductor substrate such as a single-crystal semiconductor substrate or a polycrystalline semiconductor substrate made of silicon, silicon carbide, or the like, a compound semiconductor substrate made of silicon germanium or the like, or an SOI substrate.

[0257] Next, as in Fig. As shown in Figure 7A, an opening reaching the conductive layer 172 is formed in the insulating layers 175, 174, and 173. Then, the terminal plug 176 is formed to fill the opening.

[0258] Then, as in Fig. 7A, a conductive film 151f, which becomes the conductive layers 151R, 151G, 151B, and 151C, and a conductive film 152f, which becomes the conductive layers 152R, 152G, 152B, and 152C, are formed over the terminal plug 176 and the insulating layer 175. For the conductive film 151f, for example, a metal material can be used. For the conductive film 152f, an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used.

[0259] Then, as in Fig. 7A, a photoresist mask 191 is formed over the conductive film 152f. The photoresist mask 191 can be formed by applying a light-sensitive material (photoresist), exposing it, and developing it.

[0260] Then, as in Fig. 7B, the conductive films 151f and 152f are removed, for example, in an area that does not overlap with the photoresist mask 191. In this way, the conductive layers 151 and 152 are formed.

[0261] Next, as in Fig. 7C, the photoresist mask 191 is removed. The photoresist mask 191 can be removed, for example, by ashing using oxygen plasma.

[0262] Then, as in Fig. 7D, an insulating film 156f, which becomes an insulating layer 156R, an insulating layer 156G, an insulating layer 156B, and an insulating layer 156C, is formed over the conductive layers 152R, 152G, 152B, and 152C, and the insulating layer 156F.

[0263] As the insulating film 156f, an inorganic insulating film such as an insulating oxide film, an insulating nitride film, an insulating oxynitride film, or an insulating nitride oxide film such as silicon oxynitride can be used.

[0264] Then, as in Fig. 7E, the insulating film 156f is processed to form the insulating layers 156R, 156G, 156B and 156C.

[0265] Next, as in Fig. 8A, an organic compound film 103Rf is formed over the conductive layers 152R, 152G and 152B and the insulating layer 175. As shown in Fig. 8A, the organic compound film 103Rf is not formed over the conductive layer 152C.

[0266] Then, as in Fig. 8A, a sacrificial film 158Rf and a mask film 159Rf are formed.

[0267] By providing the sacrificial film 158Rf over the organic compound film 103Rf, damage to the organic compound film 103Rf in the manufacturing process of the display device can be reduced, resulting in an increase in the reliability of the light-emitting device.

[0268] For the sacrificial film 158Rf, a film with high resistance to the processing conditions for the organic compound film 103Rf is used, particularly a film with high etching selectivity with respect to the organic compound film 103Rf. For the mask film 159Rf, a film with high etching selectivity with respect to the sacrificial film 158Rf is used.

[0269] The sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the upper temperature limit of the organic compound film 103Rf. The typical substrate temperatures in the formation of the sacrificial film 158Rf and the mask film 159Rf are respectively higher than or equal to 100°C and lower than or equal to 200°C, preferably higher than or equal to 100°C and lower than or equal to 150°C, more preferably higher than or equal to 100°C and lower than or equal to 120°C. The light-emitting device of one embodiment of the present invention contains the first organic compound and therefore enables a display device with high display quality even when manufactured by a heating process at a higher temperature.

[0270] The sacrificial film 158Rf and the mask film 159Rf are preferably films that can be removed by a wet etching process or a dry etching process.

[0271] Note that the sacrificial film 158Rf formed over and in contact with the organic compound film 103Rf is preferably formed by a formation method that is less likely to damage the organic compound film 103Rf than a formation method of the mask film 159Rf. For example, the sacrificial film 158Rf is preferably formed by an ALD method or a vacuum evaporation method rather than a sputtering method.

[0272] As both the sacrificial film 158Rf and the mask film 159Rf, for example, one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, an inorganic insulating film, and the like can be used.

[0273] For example, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing any of the metal materials, may be used for the sacrificial film 158Rf and the mask film 159Rf, respectively. In particular, a low-melting material such as aluminum or silver is preferably used. Preferably, a metal material that can block ultraviolet rays is used for the sacrificial film 158Rf and / or the mask film 159Rf. In this case, the organic compound film 103Rf can be prevented from being irradiated with ultraviolet rays during exposure for patterning, and deterioration of the organic compound film 103Rf can be prevented.

[0274] The sacrificial film 158Rf and the mask film 159Rf can each be formed using a metal oxide such as an In-Ga-Zn oxide, an indium oxide, an In-Zn oxide, an In-Sn oxide, an indium titanium oxide (In-Ti oxide), an indium tin zinc oxide (In-Sn-Zn oxide), an indium titanium zinc oxide (In-Ti-Zn oxide), an indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), or an indium tin oxide containing silicon.

[0275] In the above metal oxide, an element M (M is one or more of aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten and magnesium) may be used instead of gallium.

[0276] The sacrificial film 158Rf and the mask film 159Rf are preferably formed using a semiconductor material such as silicon or germanium for excellent compatibility with a semiconductor manufacturing process. Alternatively, a compound containing the above semiconductor material may be used.

[0277] Any of various inorganic insulating films can be used as both the sacrificial film 158Rf and the mask film 159Rf. In particular, an insulating oxide film is preferred because its adhesion to the organic compound film 103Rf is higher than that of an insulating nitride film.

[0278] Then, as in Fig. 8A, a photoresist mask 190R is formed. The photoresist mask 190R can be formed by applying a light-sensitive material (photoresist), exposing it, and developing it.

[0279] The photoresist mask 190R is provided in a position overlapping with the conductive layer 152R. The photoresist mask 190R is preferably also provided in a position overlapping with the conductive layer 152C. This can prevent the conductive layer 152C from being damaged during the process of manufacturing the display device.

[0280] Next, as in Fig. 8B, a portion of the mask film 159Rf is removed using the photoresist mask 190R, thereby forming a mask layer 159R. The mask layer 159R remains over the conductive layers 152R and 152C. Thereafter, the photoresist mask 190R is removed. Then, a portion of the sacrificial film 158Rf is removed using the mask layer 159R as a mask (also referred to as a hard mask), thereby forming a sacrificial layer 158R.

[0281] By using a wet etching method, damage to the organic compound film 103Rf during processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced compared to the case of using a dry etching method. When using a wet etching method, it is preferable to use, for example, a developing solution, an alkaline aqueous solution such as an aqueous tetramethylammonium hydroxide (TMAH) solution, or an acidic aqueous solution such as diluted hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a chemical solution containing a mixed solution of any of these acids.

[0282] In case of using a dry etching method to process the sacrificial film 158Rf, the deterioration of the organic compound film 103Rf can be prevented without using a gas containing oxygen as an etching gas.

[0283] The photoresist mask 190R can be removed by a similar method to that of the photoresist mask 191.

[0284] Next, as in Fig. 8B, the organic interconnection film 103Rf is processed to form the organic interconnection layer 103R. For example, a part of the organic interconnection film 103Rf is removed using the mask layer 159R and the sacrificial layer 158R as a hard mask, thereby forming the organic interconnection layer 103R.

[0285] Accordingly, as in Fig. 8B shows the multilayer structure of the organic interconnect layer 103R, the sacrificial layer 158R, and the mask layer 159R over the conductive layer 152R. The conductive layers 152G and 152B are exposed.

[0286] The organic compound film 103Rf is preferably processed by anisotropic etching. Anisotropic dry etching is particularly preferred. Alternatively, wet etching can be used.

[0287] In case of using a dry etching method, the deterioration of the organic compound film 103Rf can be prevented without using a gas containing oxygen as an etching gas.

[0288] A gas containing oxygen can be used as the etching gas. When the etching gas contains oxygen, the etching rate can be increased. Therefore, etching can be performed under a low-power condition while maintaining a sufficiently high etching rate. Accordingly, damage to the organic compound film 103Rf can be reduced. Furthermore, defects such as adhesion of a reaction product generated during etching can be prevented.

[0289] When using a dry etching method, for example, a gas containing at least one of H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, and a Group 18 element such as He or Ar is preferably used as the etching gas. Alternatively, a gas containing oxygen and at least one of the above is preferably used as the etching gas. Alternatively, an oxygen gas may be used as the etching gas.

[0290] Afterwards, as in Fig. 9A, an organic compound film 103Gf, which becomes the organic compound layer 103G, is formed.

[0291] The organic compound film 103Gf can be formed by a method similar to that used to form the organic compound film 103Rf. The organic compound film 103Gf can have a structure similar to that of the organic compound film 103Rf.

[0292] Then, as in Fig. 9A, a sacrificial film 158Gf and a mask film 159Gf are formed in this order. After that, the photoresist mask 190G is removed. The materials and formation methods of the sacrificial film 158Gf and the mask film 159Gf are similar to those of the sacrificial film 158Rf and the mask film 159Rf. The material and formation method of the photoresist mask 190G are similar to those of the photoresist mask 190R.

[0293] The photoresist mask 190G is provided in a position overlapping with the conductive layer 152G.

[0294] Then, as in Fig. 9B, a portion of the mask film 159Gf is removed using the photoresist mask 190G, thereby forming the mask layer 159G. The mask layer 159G remains over the conductive layer 152G. Thereafter, the photoresist mask 190G is removed. Then, a portion of the sacrificial film 158Gf is removed using the mask layer 159G as a mask, thereby forming the sacrificial layer 158G. Next, the organic interconnection film 103Gf is processed to form the organic interconnection layer 103G.

[0295] Then, as in Fig. 9C, an organic compound film 103Bf was formed.

[0296] The organic compound film 103Bf can be formed by a method similar to that used to form the organic compound film 103Rf. The organic compound film 103Bf can have a structure similar to that of the organic compound film 103Rf.

[0297] Then, as in Fig. 9C, a sacrificial film 158Bf and a mask film 159Bf are formed in this order. Next, the photoresist mask 190B is formed. The materials and formation methods of the sacrificial film 158Bf and the mask film 159Bf are similar to those of the sacrificial film 158Rf and the mask film 159Rf. The material and formation method of the photoresist mask 190B are similar to those of the photoresist mask 190R.

[0298] The photoresist mask 190B is provided in a position overlapping with the conductive layer 152B.

[0299] Then, as in Fig. 9D, a part of the mask film 159Bf is removed using the photoresist mask 190B, thereby forming the mask layer 159B. The mask layer 159B remains above the conductive layer 152B. After that, the photoresist mask 190B is removed. Then, a part of the sacrificial film 158Bf is removed using the mask layer 159B as a mask, thereby forming the sacrificial layer 158B. Next, the organic compound film 103Bf is processed to form the organic compound layer 103B. For example, a part of the organic compound film 103Bf is removed using the mask layer 159B and the sacrificial layer 158B as a hard mask, thereby forming the organic compound layer 103B.

[0300] Accordingly, as in Fig. 9D shows the multilayer structure of the organic interconnect layer 103B, the sacrificial layer 158B, and the mask layer 159B over the conductive layer 152B. The mask layers 159R and 159G are exposed.

[0301] Note that the side surfaces of the organic compound layers 103R, 103G, and 103B are preferably perpendicular or substantially perpendicular to their formation surfaces. For example, the angle between the formation surfaces and these side surfaces is preferably greater than or equal to 60° and less than or equal to 90°.

[0302] The distance between two adjacent layers among the organic compound layers 103R, 103G, and 103B formed by a photolithography method as described above can be reduced to less than or equal to 8 µm, less than or equal to 5 µm, less than or equal to 3 µm, less than or equal to 2 µm, or less than or equal to 1 µm. Here, the distance can be determined, for example, by a distance between opposite end portions of the two adjacent layers among the organic compound layers 103R, 103G, and 103B. Reducing the distance between the island-shaped organic compound layers makes it possible to provide a display device with high resolution and high aperture ratio.Furthermore, the distance between the first electrodes of adjacent light-emitting devices can also be reduced, for example, to less than or equal to 10 µm, less than or equal to 8 µm, less than or equal to 5 µm, less than or equal to 3 µm, or less than or equal to 2 µm. Note that the distance between the first electrodes of adjacent light-emitting devices is preferably greater than or equal to 2 µm and less than or equal to 5 µm.

[0303] Next, as in Fig. 10A, the mask layers 159R, 159G and 159B are preferably removed.

[0304] The mask layer removal step can be performed by a method similar to that of the mask film processing step. Specifically, damage to the organic compound layer 103 during mask layer removal can be reduced by using a wet etching method compared to the case of using a dry etching method.

[0305] The mask layers can be removed by dissolving them in a polar solvent, such as water or an alcohol. Examples of alcohols include ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), and glycerin.

[0306] After the mask layers have been removed, a drying treatment may be performed to remove water adsorbed on surfaces. For example, a heat treatment may be performed in an inert gas atmosphere or in a reduced-pressure atmosphere. The heat treatment may be performed at a substrate temperature of greater than or equal to 50°C and less than or equal to 200°C, preferably greater than or equal to 60°C and less than or equal to 150°C, more preferably greater than or equal to 70°C and less than or equal to 120°C. The heat treatment is preferably performed in a reduced-pressure atmosphere, in which case drying at a lower temperature is possible.

[0307] Next, as in Fig. 10B, an inorganic insulating film 125f is formed.

[0308] Then, as in Fig. 10C, an insulating film 127f, which becomes the insulating layer 127, is formed over the inorganic insulating film 125f.

[0309] The substrate temperature at the time of forming the inorganic insulating film 125f and the insulating film 127f is preferably higher than or equal to 60°C, higher than or equal to 80°C, higher than or equal to 100°C, or higher than or equal to 120°C and lower than or equal to 200°C, lower than or equal to 180°C, lower than or equal to 160°C, lower than or equal to 150°C, or lower than or equal to 140°C.

[0310] As the inorganic insulating film 125f, an insulating film having a thickness of greater than or equal to 3 nm, greater than or equal to 5 nm, or greater than or equal to 10 nm and less than or equal to 200 nm, less than or equal to 150 nm, less than or equal to 100 nm, or less than or equal to 50 nm is preferably formed in the above-described range of the substrate temperature.

[0311] The inorganic insulating film 125f is preferably formed, for example, by an ALD method. An ALD method is preferably used because deposition damage is reduced and a film with good coverage can be formed. As the inorganic insulating film 125f, an alumina film, for example, is preferably formed by an ALD method.

[0312] The insulating film 127f is preferably formed by the aforementioned wet process. The insulating film 127f is preferably formed, for example, by spin coating using a photosensitive material, and particularly preferably using a photosensitive resin composition containing an acrylic resin.

[0313] Then, a portion of the insulating film 127f is exposed to visible light or ultraviolet rays. The insulating layer 127 is formed in regions located between any two of the conductive layers 152R, 152G, and 152B, and around the conductive layer 152C.

[0314] The width of the later-formed insulating layer 127 can be controlled by the exposed area of the insulating film 127f. In this embodiment, the processing is performed such that the insulating layer 127 includes a portion overlapping with the upper surface of the conductive layer 151.

[0315] The light used for exposure preferably contains the i-line (wavelength: 365 nm). Furthermore, the light used for exposure may contain at least one of the g-line (wavelength: 436 nm) and the h-line (wavelength: 405 nm).

[0316] Next, as in Fig. 11A, development is performed to remove the exposed portion of the insulating film 127f, thereby forming an insulating layer 127a.

[0317] Next, as in Fig. 11B, an etching treatment is performed using the insulating layer 127a as a mask to remove a part of the inorganic insulating film 125f and reduce the thickness of a part of the sacrificial layers 158R, 158G, and 158B. Therefore, the inorganic insulating layer 125f is formed under the insulating layer 127a. In addition, the surfaces of the thin portions of the sacrificial layers 158R, 158G, and 158B are exposed. Note that the etching treatment using the insulating layer 127a as a mask may be referred to as a first etching treatment hereinafter.

[0318] The first etching treatment can be performed by dry etching or wet etching. Note that the inorganic insulating film 125f is preferably formed using a similar material to that of the sacrificial layers 158R, 158G, and 158B, in which case the first etching treatment can be performed simultaneously.

[0319] In the case where dry etching is performed, a chlorine-based gas is preferably used. As the chlorine-based gas, one of Cl2, BCl3, SiCl4, CCl4, and the like, or a mixture of two or more of them, can be used. Furthermore, one of an oxygen gas, a hydrogen gas, a helium gas, an argon gas, and the like, or a mixture of two or more of them, can be added to the chlorine-based gas as needed. By dry etching, the thin portions of the sacrificial layers 158R, 158G, and 158B can be formed with favorable in-plane uniformity.

[0320] A dry etching device comprising a high-density plasma source can be used as the dry etching device. For example, an inductively coupled plasma (ICP) etching device can be used as the dry etching device comprising a high-density plasma source. Alternatively, a capacitively coupled plasma (CCP) etching device comprising parallel plate electrodes can be used.

[0321] The first etching treatment is preferably performed by wet etching. Using wet etching can reduce damage to the organic compound layers 103R, 103G, and 103B compared to the case of using dry etching. Wet etching can be performed using an alkaline solution, for example. For example, TMAH, which is an alkaline solution, can be used for wet etching an aluminum oxide film. Alternatively, an acid solution containing fluoride can also be used. In this case, puddle wet etching can be performed. Note that the inorganic insulating film 125f is preferably formed using a similar material to that used for the sacrificial layers 158R, 158G, and 158B, in which case the first etching treatment can be performed simultaneously.

[0322] The sacrificial layers 158R, 158G, and 158B are not completely removed by the first etching treatment, and the etching treatment is interrupted when the thicknesses of the sacrificial layers 158R, 158G, and 158B are reduced. The sacrificial layers 158R, 158G, and 158B thus remain above the corresponding organic interconnect layers 103R, 103G, and 103B, which can prevent the organic interconnect layers 103R, 103G, and 103B from being damaged by treatment in a later step.

[0323] Subsequently, exposure is preferably performed on the entire substrate such that the insulating layer 127a is irradiated with visible light or ultraviolet rays. The energy density for exposure is preferably higher than 0 mJ / cm 2 and less than or equal to 800 mJ / cm 2 , preferably higher than 0 mJ / cm 2 and less than or equal to 500 mJ / cm 2Performing such exposure after development can, in some cases, increase the degree of transparency of the insulating layer 127a. Furthermore, in some cases, it is possible to lower the substrate temperature required for the subsequent heat treatment for changing the shape of the insulating layer 127a into a tapered shape.

[0324] Here, if an insulating barrier layer against oxygen (e.g., an aluminum oxide film) exists as each of the sacrificial layers 158R, 158G, and 158B, the diffusion of oxygen into the organic compound layers 103R, 103G, and 103B can be prevented.

[0325] Then, a heat treatment (also called post-baking) is performed. The heat treatment can change the insulating layer 127a into the insulating layer 127 with a tapered side surface ( Fig. 11C). The heat treatment is performed at a temperature lower than the upper temperature limit of the organic compound layer. The heat treatment can be performed at a substrate temperature of higher than or equal to 50°C and lower than or equal to 200°C, preferably higher than or equal to 60°C and lower than or equal to 150°C, more preferably higher than or equal to 70°C and lower than or equal to 130°C. The heating atmosphere can be an air atmosphere or an inert gas atmosphere. Furthermore, the heating atmosphere can be an atmospheric pressure atmosphere or a reduced pressure atmosphere. Accordingly, the adhesion between the insulating layer 127 and the inorganic insulating layer 125 can be improved, and the corrosion resistance of the insulating layer 127 can be increased.

[0326] If the sacrificial layers 158R, 158G, and 158B are not completely removed by the first etching treatment and the thinned sacrificial layers 158R, 158G, and 158B remain, the organic compound layers 103R, 103G, and 103B can be prevented from being damaged and deteriorated during the heat treatment. This can increase the reliability of the light-emitting device.

[0327] Next, as in Fig. 12A, an etching treatment is performed using the insulating layer 127 as a mask to remove portions of the sacrificial layers 158R, 158G, and 158B. Thus, openings are formed in the sacrificial layers 158R, 158G, and 158B, and the upper surfaces of the organic interconnect layers 103R, 103G, and 103B and the conductive layer 152C are exposed. Note that this etching treatment may be referred to as a second etching treatment hereinafter.

[0328] An end portion of the inorganic insulating layer 125 is covered with the insulating layer 127. Fig. 12A illustrates an example in which a part of the end portion of the sacrificial layer 158G (specifically, a tapered portion formed by the first etching treatment) is covered with the insulating layer 127, and a tapered portion formed by the second etching treatment is exposed.

[0329] The second etching treatment is performed by wet etching. Using wet etching can reduce damage to the organic compound layers 103R, 103G, and 103B compared to using dry etching. Wet etching can be performed using, for example, an alkaline solution or an acid solution. An aqueous solution is preferably used so that the organic compound layer 103 is not dissolved.

[0330] Next, as in Fig. 12B, a common electrode 155 is formed over the organic interconnect layers 103R, 103G, and 103B, the conductive layer 152C, and the insulating layer 127. The common electrode 155 can be formed by a sputtering method, a vacuum evaporation method, or the like.

[0331] Next, as in Fig. As shown in Figure 12C, the protective layer 131 is formed over the common electrode 155. The protective layer 131 may be formed by a vacuum evaporation method, a sputtering method, a CVD method, an ALD method, or the like.

[0332] Then, the substrate 120 is bonded to the protective layer 131 using the resin layer 122, so that the display device can be manufactured.

[0333] As described above, in the method for manufacturing the display device of one embodiment of the present invention, the island-shaped organic compound layers 103R, 103G, and 103B are each formed not by using a fine metal mask but by processing a film formed on the entire surface; therefore, the island-shaped layers can be formed to have a uniform thickness. Furthermore, a high-resolution display device or a high-aperture display device can be obtained. Furthermore, even when the resolution or aperture ratio is high and the pitch between subpixels is very short, the organic compound layers 103R, 103G, and 103B can be prevented from being in contact with each other in the adjacent subpixels. As a result, the generation of the leakage current between the subpixels can be prevented.This can prevent crosstalk, allowing a display device with very high contrast to be obtained. Furthermore, even a display device comprising tandem light-emitting devices formed by a photolithography process can exhibit advantageous characteristics. (Embodiment 4)

[0334] In this embodiment, a display device of an embodiment of the present invention will be described.

[0335] The display device in this embodiment may be a high-resolution display device. Therefore, the display device in this embodiment can be used for display sections of information terminals (wearable devices) such as wristwatch-type and bracelet-type information terminals, and display sections of head-mounted wearable devices such as a VR device such as a head-mounted display (HMD) and a glasses-type AR device.

[0336] The display device in this embodiment may be a high-definition display device or a large-scale display device. Accordingly, the display device in this embodiment can be used for display sections of a digital camera, a digital video camera, a digital photo frame, a mobile phone, a portable game console, a portable information terminal, and an audio playback device, in addition to display sections of electronic devices with a relatively large screen such as a television, a desktop or notebook PC, a computer monitor, and the like, a digital signage device, and a large-scale gaming machine such as a pinball machine. [Display module]

[0337] Fig. 13A is a perspective view of a display module 280. The display module 280 includes a display device 100A and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100A and may be any of the display devices 100B to 100E described later.

[0338] The display module 280 includes a substrate 291 and a substrate 292. The display module 280 includes a display section 281. The display section 281 is a region of the display module 280 on which an image is displayed, and is a region in which light emitted from pixels provided in a pixel section 284 described later can be seen.

[0339] Fig. 13B is a perspective view schematically illustrating the structure on the side of the substrate 291. A circuit portion 282, a pixel circuit portion 283, and the pixel portion 284 are stacked above the substrate 291. Furthermore, a terminal portion 285 for connecting to the FPC 290 is included in a portion above the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected to each other via a wiring portion 286 formed of a plurality of wires.

[0340] The pixel section 284 includes a plurality of pixels 284a arranged periodically. An enlarged view of a pixel 284a is shown on the right side in Fig. 13B. Any of the structures described in the previous embodiments may be applied to the pixels 284a.

[0341] The pixel circuit section 283 includes a plurality of pixel circuits 283a arranged periodically.

[0342] A pixel circuit 283a is a circuit that controls the operation of a plurality of elements included in a pixel 284a.

[0343] The circuit section 282 includes circuitry for operating the pixel circuits 283a in the pixel circuit section 283. For example, the circuit section 282 preferably includes a gate line driver circuit and / or a source line driver circuit. The circuit section 282 may also include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0344] The FPC 290 serves as a line for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may be mounted on the FPC 290.

[0345] The display module 280 may have a structure in which the pixel circuit portion 283 and / or the circuit portion 282 are arranged below the pixel portion 284; therefore, the aperture ratio (the effective display area ratio) of the display portion 281 can be significantly high.

[0346] Such a display module 280 has a very high resolution and can therefore be suitably used for a VR device such as an HMD or a glasses-type AR device. For example, even in the case of a structure in which the display portion of the display module 280 is viewed through a lens, pixels of the very high-resolution display portion 281 included in the display module 280 are prevented from being recognized when the display portion is magnified by the lens, so that display providing a high sense of immersion can be performed. Without being limited thereto, the display module 280 can be suitably used for electronic devices including a relatively small display portion. [Indicator 100A]

[0347] The Fig. The display device 100A shown in Figure 14A includes a substrate 301, the light-emitting devices 130R, 130G, and 130B, a capacitor 240, and a transistor 310.

[0348] The substrate 301 corresponds to the substrate 291 in Fig. 14A and Fig. 14B. The transistor 310 includes a channel formation region in the substrate 301. For example, a semiconductor substrate such as a single-crystal silicon substrate can be used as the substrate 301. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 serves as a gate electrode. The insulating layer 313 is positioned between the substrate 301 and the conductive layer 311 and serves as a gate insulating layer. The low-resistance region 312 is a region where the substrate 301 is doped with an impurity and serves as a source or drain. The insulating layer 314 is provided to cover the side surface of the conductive layer 311.

[0349] An element isolation layer 315 is provided between two adjacent transistors 310 such that it is embedded in the substrate 301.

[0350] An insulating layer 261 is provided to cover the transistor 310, and the capacitor 240 is provided over the insulating layer 261.

[0351] The capacitor 240 includes a conductive layer 241, a conductive layer 245, and an insulating layer 243 between the conductive layers 241 and 245. The conductive layer 241 serves as one electrode of the capacitor 240, the conductive layer 245 serves as the other electrode of the capacitor 240, and the insulating layer 243 serves as the dielectric of the capacitor 240.

[0352] The conductive layer 241 is provided over the insulating layer 261 and is embedded in an insulating layer 254. The conductive layer 241 is electrically connected to a source and drain terminal of the transistor 310 via a terminal plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0353] An insulating layer 255 is provided to cover the capacitor 240. The insulating layer 174 is provided over the insulating layer 255. The insulating layer 175 is provided over the insulating layer 174. The light-emitting devices 130R, 130G, and 130B are provided over the insulating layer 175. An insulator is provided in regions between adjacent light-emitting devices.

[0354] The insulating layer 156R is provided to include a region overlapping the side surface of the conductive layer 151R. The insulating layer 156G is provided to include a region overlapping the side surface of the conductive layer 151G. The insulating layer 156B is provided to include a region overlapping the side surface of the conductive layer 151B. The conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R. The conductive layer 152G is provided to cover the conductive layer 151G and the insulating layer 156G. The conductive layer 152B is provided to cover the conductive layer 151B and the insulating layer 156B. The sacrificial layer 158R is positioned over the organic interconnect layer 103R.The sacrificial layer 158G is positioned over the organic interconnect layer 103G. The sacrificial layer 158G is positioned over the organic interconnect layer 103B.

[0355] Each of the conductive layers 151R, 151G, and 151B is electrically connected to a source and drain terminal of the corresponding transistor 310 via a terminal plug 256 embedded in the insulating layers 243, 255, 174, and 175, the conductive layer 241 embedded in the insulating layer 254, and the terminal plug 271 embedded in the insulating layer 261. Any of various conductive materials can be used for the terminal plugs.

[0356] The protective layer 131 is provided over the light-emitting devices 130R, 130G, and 130B. The substrate 120 is bonded to the protective layer 131 by means of the resin layer 122. Reference can be made to Embodiment 3 for the details of the light-emitting device 130 and the components thereabove up to the substrate 120. The substrate 120 corresponds to the substrate 292 in Fig. 13A.

[0357] Fig. 14B shows a variation example of the Fig. 14A. The display device 100A shown in Fig. 14B comprises a color layer 132R, a color layer 132G, and a color layer 132B, and each of the light-emitting devices 130 includes a region overlapping with one of the color layers 132R, 132G, and 132B. In the display device shown in Fig. In the display device shown in Figure 14B, the light-emitting device 130 can emit white light, for example. The color layer 132R, the color layer 132G, and the color layer 132B can transmit red light, green light, and blue light, for example, respectively. [Display device 100B]

[0358] Fig. 15 is a perspective view of the display device 100B, and Fig. 16 is a cross-sectional view of the display device 100C.

[0359] In the display device 100B, a substrate 352 and a substrate 351 are bonded together. In Fig. 15, the substrate 352 is represented by a dashed line.

[0360] The display device 100B includes the pixel portion 177, the connection portion 140, a circuit 356, a wiring 355, and the like. Fig. 15 shows an example in which an IC 354 and an FPC 353 are mounted on the display device 100B. Therefore, the Fig. The structure shown in Figure 15 can be regarded as a display module including the display device 100B, the integrated circuit (IC), and the FPC. Here, a display device in which a substrate is provided with a terminal such as an FPC or is mounted with an IC is referred to as a display module.

[0361] The connection portion 140 is provided outside the pixel portion 177. The number of connection portions 140 may be one or more. In the connection portion 140, a common electrode of a light-emitting device is electrically connected to a conductive layer so that a potential can be supplied to the common electrode.

[0362] For example, a scan line driver circuit can be used as circuit 356.

[0363] The line 355 has a function of supplying a signal and a current to the pixel portion 177 and the circuit 356. The signal and current are input to the line 355 from the outside via the FPC 353 or from the IC 354.

[0364] Fig. 15 illustrates an example in which the IC 354 is provided over the substrate 351 by a chip-on-glass (COG) method, a chip-on-film (COF) method, or the like. For example, an IC including a scanning line driver circuit, a signal line driver circuit, or the like can be used as the IC 354. Note that the display device 100B and the display module are not necessarily provided with an IC. Alternatively, the IC may be mounted on the FPC by, for example, a COF method.

[0365] Fig. 16 illustrates the display device 100C as an example of cross sections of a part of an area including the FPC 353, a part of the circuit 356, a part of the pixel portion 177, a part of the connection portion 140, and a part of an area including an end portion of the display device 100B. Fig. 15. [Display device 100C]

[0366] The Fig. The display device 100C shown in Fig. 16 includes a transistor 201, a transistor 205, the light-emitting device 130R that emits red light, the light-emitting device 130G that emits green light, the light-emitting device 130B that emits blue light, and the like between the substrate 351 and the substrate 352.

[0367] For the details of the light-emitting devices 130R, 130G and 130B, reference can be made to Embodiment 3.

[0368] Light-emitting device 130R includes conductive layer 224R, conductive layer 151R over conductive layer 224R, and conductive layer 152R over conductive layer 151R. Light-emitting device 130G includes conductive layer 224G, conductive layer 151G over conductive layer 224G, and conductive layer 152G over conductive layer 151G. Light-emitting device 130B includes conductive layer 224B, conductive layer 151B over conductive layer 224B, and conductive layer 152B over conductive layer 151B.

[0369] The conductive layer 224R is connected to a conductive layer 222b included in the transistor 205 via an opening provided in an insulating layer 214. An end portion of the conductive layer 151R is positioned further outward than an end portion of the conductive layer 224R. The insulating layer 156R is provided to include a region in contact with the side surface of the conductive layer 151R, and the conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R.

[0370] The conductive layers 224G, 151G, and 152G, and the insulating layer 156G in the light-emitting device 130G are not described in detail because they are similar to the conductive layers 224R, 151R, and 152R, and the insulating layer 156R in the light-emitting device 130R, respectively; the same applies to the conductive layers 224B, 151B, and 152B, and the insulating layer 156B in the light-emitting device 130B.

[0371] The conductive layers 224R, 224G, and 224B each include a recessed portion covering the opening provided in the insulating layer 214. A layer 128 is embedded in the recessed portion.

[0372] Layer 128 has a function of filling the recessed portions of conductive layers 224R, 224G, and 224B to maintain planarity. Conductive layers 151R, 151G, and 151B, which are electrically connected to conductive layers 224R, 224G, and 224B, are provided above conductive layers 224R, 224G, and 224B, respectively. Therefore, the regions overlapping the recessed portions of conductive layers 224R, 224G, and 224B can also be used as light-emitting regions, thereby increasing the aperture ratio of the pixel.

[0373] The layer 128 may be an insulating layer or a conductive layer. Any of various inorganic insulating materials, organic insulating materials, and conductive materials may be appropriately used for the layer 128. In particular, the layer 128 is preferably formed using an insulating material, and is particularly preferably formed using an organic insulating material. For example, the layer 128 may be formed using an organic insulating material usable for the insulating layer 127.

[0374] The protective layer 131 is provided over the light-emitting devices 130R, 130G, and 130B. The protective layer 131 and the substrate 352 are bonded together with an adhesive layer 142. The substrate 352 is provided with an opaque layer 157. A solid sealing structure, a hollow sealing structure, or the like can be used to seal the light-emitting device 130. Fig. 16, a solid sealing structure is employed in which a space between the substrate 352 and the substrate 351 is filled with the adhesive layer 142. Alternatively, the space may be filled with an inert gas (e.g., nitrogen or argon), that is, a hollow sealing structure may be employed. In this case, the adhesive layer 142 may be provided such that it does not overlap with the light-emitting device. Alternatively, the space may be filled with a resin other than the frame-like adhesive layer 142.

[0375] Fig. 16 illustrates an example in which the connecting portion 140 includes a conductive layer 224C obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, the conductive layer 151C obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and the conductive layer 152C obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. In the example shown in Fig. In the example shown in Fig. 16, the insulating layer 156C is provided to include a region overlapping with the side surface of the conductive layer 151C.

[0376] The display device 100C has a top-emission structure. Light from the light-emitting device is emitted toward the substrate 352. A material having high visible light transmittance is preferably used for the substrate 352. The pixel electrode includes a material that reflects visible light, and the counter electrode (the common electrode 155) includes a material that transmits visible light.

[0377] Above the substrate 351, an insulating layer 211, an insulating layer 213, an insulating layer 215, and the insulating layer 214 are provided in this order. A part of the insulating layer 211 serves as the gate insulating layer of each transistor. A part of the insulating layer 213 serves as the gate insulating layer of each transistor. The insulating layer 215 is provided to cover the transistors. The insulating layer 214 is provided to cover the transistors and has a function as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and they may each be one or more.

[0378] An inorganic insulating film is preferably used as each of the insulating layers 211, 213 and 215.

[0379] An organic insulating layer is suitable for the insulating layer 214, which serves as a planarization layer.

[0380] The transistors 201 and 205 each include a conductive layer 221 serving as a gate, the insulating layer 211 serving as a gate insulating layer, a conductive layer 222a and the conductive layer 222b serving as a source and drain, a semiconductor layer 231, the insulating layer 213 serving as a gate insulating layer, and a conductive layer 223 serving as a gate.

[0381] A connecting portion 204 is provided in a region of the substrate 351 that does not overlap with the substrate 352. In the connecting portion 204, the source electrode or the drain electrode of the transistor 201 is electrically connected to the FPC 353 via a conductive layer 166 and an interconnection layer 242. For example, the conductive layer 166 has a multilayer structure composed of the following films: a conductive film obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B; a conductive film obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B; and a conductive film obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. At the top of the connecting portion 204, the conductive layer 166 is exposed.Thus, the connecting portion 204 and the FPC 353 can be electrically connected to each other via the connecting layer 242.

[0382] The opaque layer 157 is preferably provided on the surface of the substrate 352 on the side of the substrate 351. The opaque layer 157 may be provided over an area between adjacent light-emitting devices, in the connecting portion 140, in the circuit 356, and the like. Various optical components may be arranged on the outside of the substrate 352.

[0383] A material that can be used for the substrate 120 can be used for each of the substrates 351 and 352.

[0384] A material that can be used for the resin layer 122 can be used for the adhesive layer 142.

[0385] An anisotropic conductive film (ACF), anisotropic conductive paste (ACP), or the like can be used as the connecting layer 242. [Display device 100D]

[0386] The Fig. The display device 100D shown in Figure 17 differs from that shown in Fig. 16 mainly in that it has a bottom emission structure.

[0387] Light from the light-emitting device is emitted toward the substrate 351. A material having high visible light transmittance is preferably used for the substrate 351. In contrast, there is no limitation on the light transmittance of a material used for the substrate 352.

[0388] An opaque layer 317 is preferably formed between the substrate 351 and the transistor 201 and between the substrate 351 and the transistor 205. Fig. 17 illustrates an example in which the opaque layer 317 is provided over the substrate 351, an insulating layer 153 is provided over the opaque layer 317, and the transistors 201 and 205 and the like are provided over the insulating layer 153.

[0389] The light-emitting device 130R includes a conductive layer 112R, a conductive layer 126R over the conductive layer 112R, and a conductive layer 129R over the conductive layer 126R.

[0390] The light-emitting device 130B includes a conductive layer 112B, a conductive layer 126B over the conductive layer 112B, and a conductive layer 129B over the conductive layer 126B.

[0391] A material with high visible light transmittance is used for each of the conductive layers 112R, 112B, 126R, 126B, 129R, and 129B. A material that reflects visible light is preferably used for the second electrode 102.

[0392] Although in Fig. 17, the light-emitting device 130G is also provided.

[0393] Although Fig. 17 and the like illustrate an example in which the top surface of the layer 128 includes a flat portion, the shape of the layer 128 is not particularly limited. [Display device 100D2]

[0394] The Fig. The display device 100D2 shown in Figure 18A is an example of a bottom emission display device which differs from the one shown in Fig. 17. The display device 100D2 differs from the display device 100D in that it includes an organic resin layer 180. It should be noted that the reference numerals of the components corresponding to those in Fig. 17 are the same, in some cases are omitted and for the details of such components, please refer to the description for Fig. 17 is referred to.

[0395] Fig. 18B is a top view layout of pixel 178 (pixels 178a and 178b) including subpixel 110 (subpixels 110R, 110G, and 110B, and subpixel 110W), and Fig. 18C is a plan view of the organic resin layer 180 in a region where the subpixels 110R and 110G are formed in the pixel 178. A region of the subpixel 110R between the light-opaque layers 317 can be represented as a width 110Rw in a light-emitting region.

[0396] As in Fig. 18A, the organic resin layer 180 is provided over the insulating layer 214. As shown in Fig. 18C and the area in Fig. As shown in FIG. 18A surrounded by the dashed line, the organic resin layer 180 includes a recessed portion 181 (recessed portions 181a and 181b) having a curved surface at least in a region where the subpixel is formed. Note that the recessed portion 181 may be provided outside the light-emitting region, such as a recessed portion 181c. With the recessed portion 181c, light emission caused in a region overlapping with the light-blocking layer 317 or light advancing to the region overlapping with the light-blocking layer 317 can be refracted and extracted from the light-emitting region, whereby the emission efficiency can be improved.

[0397] A plurality of recessed portions 181 may be formed in a matrix. The recessed portions 181a and 181b may be provided in contact with each other or may be provided to have a flat surface therebetween.

[0398] Although the top surface shape and the cross-sectional shape of the recessed section are hexagonal ( Fig. 18C) or semicircular ( Fig. 18A), other shapes may be used as needed. Examples of the top surface shape of the recessed portion include polygons such as a triangle, a quadrilateral (including a rectangle and a square), and a pentagon; polygons with rounded corners; an ellipse; and a circle.

[0399] An insulating layer containing an organic material can be used as the organic resin layer 180. Examples of materials used for the organic resin layer 180 include an acrylic resin, a polyimide resin, an epoxy resin, an imide resin, a polyamide resin, a polyimidamide resin, a silicone resin, a siloxane resin, a benzocyclobutene-based resin, a phenolic resin, and precursors of these resins. The organic resin layer 180 can be formed using an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or an alcohol-soluble polyamide resin.

[0400] A photosensitive resin can also be used for the organic resin layer 180. A photoresist can be used as the photosensitive resin. A positive photosensitive material or a negative photosensitive material can be used as the photosensitive resin.

[0401] The organic resin layer 180 may contain a material that absorbs visible light. For example, the organic resin layer 180 itself may be formed from a material that absorbs visible light, or the organic resin layer 180 may contain a pigment that absorbs visible light. For example, the organic resin layer 180 may be formed using a resin that can be used as a color filter that transmits red, blue, or green light and absorbs light of other colors, or a resin that contains carbon black as a pigment and serves as a black matrix.

[0402] The first electrode 101 (the first electrode 101R and a first electrode 101W) is located above the organic resin layer 180, and the organic compound layer 103 is located above the first electrode 101. End portions of the first electrodes 101 and the organic compound layer 103 may be covered with the insulating layer 127.

[0403] The first electrode 101 formed over the organic resin layer 180 also includes a depressed portion along the depressed portion of the organic resin layer 180. The organic interconnection layer 103 formed over the first electrode 101 also includes a depressed portion along the depressed portion of the first electrode 101. The common layer 104 formed over the organic interconnection layer 103 also includes a depressed portion along the depressed portion of the organic interconnection layer 103. The second electrode 102 formed over the common layer 104 also includes a depressed portion along the depressed portion of the common layer 104. That is, the depressed portions of the organic resin layer 180, the first electrode 101, the organic interconnection layer 103, the common layer 104, and the second electrode 102 overlap each other.

[0404] The common layer 104 is provided over the organic compound layer 103 and the insulating layer 127, and the second electrode 102 is provided over the common layer 104. The protective layer 131 is provided over the second electrode 102 and bonded to the substrate 352 with the adhesive layer 142 therebetween.

[0405] Although the light-emitting devices 130G and 130B are not Fig. 18A to Fig. 18C, the light-emitting devices 130G and 130B are also provided. [Display device 100E]

[0406] The Fig. The display device 100E shown in Fig. 19 is a variation example of the display device 100E shown in Fig. 16 and differs from the display device 100C mainly in that it includes the color layers 132R, 132G and 132B.

[0407] In the display device 100E, the light-emitting device 130 includes a region overlapping with one of the color layers 132R, 132G, and 132B. The color layers 132R, 132G, and 132B may be provided on a surface of the substrate 352 on the side of the substrate 351. End portions of the color layers 132R, 132G, and 132B may overlap with the light-blocking layer 157.

[0408] In the display device 100E, the light-emitting device 130 can emit white light, for example. The color layer 132R, the color layer 132G, and the color layer 132B can transmit red light, green light, and blue light, for example, respectively. Note that in the display device 100E, the color layers 132R, 132G, and 132B can be provided between the protective layer 131 and the adhesive layer 142. [Display device 100E2]

[0409] One in Fig. The display device 100E2 shown in Fig. 20A is a variation example of the display device 100E2 shown in Fig. 19 and includes microlenses 182 over the color layers 132R, 132G and 132B. It should be noted that the reference numerals of the components corresponding to those in Fig. 19 are the same, in some cases they are omitted and for the details of such components, please refer to the description for Fig. 19 is referred to.

[0410] Fig. 20B is a top view layout of pixel 178 (pixels 178a and 178b) including subpixel 110 (subpixels 110R, 110G, and 110B), and Fig. 20C is a plan view of the microlenses 182 in a region where the subpixels 110R and 110G are formed in the pixel 178. A region of the subpixel 110G in which the common electrode 155 and the EL layer 103 are in contact with each other can be represented as a width 110Gw in a light-emitting region.

[0411] At the Fig. In the display device 100E2 shown in FIG. 20A, a planarization film 143 is provided over the protective layer 131, and the color layers 132R, 132G, and 132B are provided over the planarization film 143. The planarization film 144 is provided to cover the color layers 132R, 132G, and 132B. The microlenses 182 are provided over the planarization film 144.

[0412] It should be noted that, as in Fig. 20C, the microlens 182 is preferably provided for each of the subpixels in a region in which the subpixel is formed.

[0413] Although the top surface shape of the microlens 182 in Fig. 20C is shown as a hexagon, other shapes may be used as needed. Examples of the top surface shape of the microlens 182 include polygons such as a triangle, a quadrilateral (including a rectangle and a square), and a pentagon; polygons with rounded corners; an ellipse; and a circle.

[0414] The microlens 182 may be formed using a material similar to that of the organic resin layer 180.

[0415] This embodiment can be appropriately combined with other embodiments or examples. In the case where a plurality of structural examples are shown in one embodiment in this specification, the structural examples can be combined as needed. (Embodiment 5)

[0416] In this embodiment, electronic devices of embodiments of the present invention are described.

[0417] Electronic devices in this embodiment each include the display device of one embodiment of the present invention in a display section. The display device of one embodiment of the present invention has low power consumption and high reliability. Therefore, the display device of one embodiment of the present invention can be used for display sections of various electronic devices.

[0418] Examples of the electronic devices include, in addition to electronic devices having a relatively large screen such as a television, desktop and notebook PCs, a monitor of a computer and the like, a digital signage and a large gaming machine such as a pinball machine, a digital camera, a digital video camera, a digital photo frame, a mobile phone, a portable game console, a portable information terminal and an audio playback device.

[0419] Based on Fig. 21A to Fig. 21D describes examples of wearable devices that can be worn on the head.

[0420] One in Fig. 21A and an electronic device 700A shown in Fig. 21B each include a pair of display panels 751, a pair of housings 721, a communication section (not shown), a pair of wearing sections 723, a control section (not shown), an imaging section (not shown), a pair of optical components 753, a frame 757, and a pair of nose pads 758.

[0421] The display device of one embodiment of the present invention can be used for the display panels 751. Therefore, a highly reliable electronic device is obtained.

[0422] The electronic devices 700A and 700B can each project images displayed on the display panels 751 onto display areas 756 of the optical components 753. Since the optical components 753 have a light transmission property, the user can see images displayed on the display areas superimposed on transmission images viewed through the optical components 753.

[0423] In the electronic devices 700A and 700B, a camera capable of front-facing imaging may be provided as an imaging section. Furthermore, when the electronic devices 700A and 700B are provided with an acceleration sensor such as a gyroscope sensor, the orientation of the user's head may be detected, and an image corresponding to the orientation may be displayed on the display areas 756.

[0424] The communication section includes a wireless communication device, and a video signal can be supplied, for example, through the wireless communication device. Instead of the wireless communication device or in addition thereto, a connecting element that can be connected to a cable for supplying a video signal and a power supply potential can be provided.

[0425] The 700A and 700B electronic devices are provided with a battery so that they can be charged contactless and / or with a cable.

[0426] A touch sensor module may be provided in the housing 721.

[0427] Various touch sensors can be applied to the touch sensor module. For example, any of the following touch sensors can be used: a capacitive type, a resistive type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, and an optical type. In particular, a capacitive sensor or an optical sensor is preferably used for the touch sensor module.

[0428] One in Fig. 21C shown electronic device 800A and a Fig. 21D each include a pair of display sections 820, a housing 821, a communication section 822, a pair of carrying sections 823, a control section 824, a pair of imaging sections 825, and a pair of lenses 832.

[0429] The display device of one embodiment of the present invention can be used in the display sections 820. Therefore, a highly reliable electronic device is obtained.

[0430] The display sections 820 are positioned within the housing 821 so as to be viewed through the lenses 832. When the pair of display sections 820 display different images, a three-dimensional display can be performed using parallax.

[0431] The electronic devices 800A and 800B preferably include a mechanism for adjusting the lateral positions of the lenses 832 and the display sections 820 so that the lenses 832 and the display sections 820 are optimally positioned according to the positions of the user's eyes.

[0432] The electronic device 800A or the electronic device 800B can be mounted on the user's head with the wearable sections 823.

[0433] The imaging section 825 has a function of obtaining information about the external environment. Data obtained by the imaging section 825 can be output to the display section 820. An image sensor can be used for the imaging section 825. In addition, a plurality of cameras can be provided to support a variety of fields of view, such as a telescopic field of view and a wide-angle field of view.

[0434] The electronic device 800A may include a vibrating mechanism that serves as a bone conduction earphone.

[0435] The electronic devices 800A and 800B may each include an input terminal. A cable for supplying a video signal from a video output device or the like, power for charging a battery provided in the electronic device, and the like may be connected to the input terminal.

[0436] The electronic device of one embodiment of the present invention may have a function for performing wireless communication with earphones 750.

[0437] The electronic device may include an earphone portion. Fig. 21B includes earphone portions 727. A portion of a wire connecting the earphone portion 727 and the control portion may be positioned within the housing 721 or the carrying portion 723.

[0438] Similarly, the Fig. 21D, the electronic device 800B includes earphone portions 827. For example, the earphone portion 827 may be connected to the control portion 824 via a line.

[0439] As described above, both the eyeglass-like device (e.g., the electronic devices 700A and 700B) and the goggle-like device (e.g., the electronic devices 800A and 800B) are preferable as the electronic device of an embodiment of the present invention.

[0440] One in Fig. Electronic device 6500 shown in Figure 22A is a portable information terminal that can be used as a smartphone.

[0441] The electronic device 6500 includes a housing 6501, a display section 6502, a power button 6503, buttons 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, and the like. The display section 6502 has a touchscreen function.

[0442] The display device of one embodiment of the present invention can be used in the display section 6502. Therefore, a highly reliable electronic device is obtained.

[0443] Fig. 22B is a schematic cross-sectional view including an end portion of the housing 6501 on the side of the microphone 6506.

[0444] A protective component 6510 having light transmittance is provided on the display surface side of the housing 6501. A display panel 6511, an optical component 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, and the like are provided in a space enclosed by the housing 6501 and the protective component 6510.

[0445] The display panel 6511, the optical component 6512 and the touch sensor panel 6513 are attached to the protective component 6510 with a fixing layer (not shown).

[0446] A portion of the display panel 6511 is folded back in an area outside the display section 6502, and an FPC 6515 is connected to the folded back portion. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on the printed circuit board 6517.

[0447] The display device of one embodiment of the present invention can be used in the display panel 6511. Therefore, a very lightweight electronic device can be achieved. Since the display panel 6511 is very thin, the high-capacity battery 6518 can be mounted without increasing the thickness of the electronic device. In addition, a part of the display panel 6511 is folded back to provide a connection portion with the FPC 6515 on the back of the pixel portion, thereby achieving an electronic device with a narrow frame.

[0448] Fig. 22C illustrates an example of a television set. In a television set 7100, a display section 7000 is installed in a housing 7171. Here, the housing 7171 is supported by a base 7173.

[0449] The display device of one embodiment of the present invention can be used in the display section 7000. Therefore, a highly reliable electronic device is obtained.

[0450] An operation of the Fig. 22C can be performed with an operating switch provided in the housing 7171 and a separate remote control 7151.

[0451] Fig. 22D illustrates an example of a notebook PC. A notebook PC 7200 includes a case 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. The display section 7000 is installed in the case 7211.

[0452] The display device of one embodiment of the present invention can be used in the display section 7000. Therefore, a highly reliable electronic device is obtained.

[0453] Fig. 22E and Fig. 22F show examples of digital signage.

[0454] One in Fig. The digital signage 7300 illustrated in Figure 22E includes a housing 7301, the display section 7000, a speaker 7303, and the like. The digital signage 7300 may also include an LED lamp, an operation button (including a power button or an operation switch), a connection port, various sensors, a microphone, and the like.

[0455] Fig. 22F illustrates a digital signage 7400 mounted on a cylindrical column 7401. The digital signage 7400 includes the display portion 7000 provided along a curved surface of the column 7401.

[0456] In Fig. 22E and Fig. 22F, the display device of one embodiment of the present invention can be used in the display section 7000. Therefore, a highly reliable electronic device is obtained.

[0457] A larger area of the display section 7000 can increase the amount of information that can be provided at once. The larger display section 7000 attracts more attention, so that, for example, the effectiveness of the advertisement can be increased.

[0458] As in Fig. 22E and Fig. 22F, it is preferred that the digital signage 7300 or the digital signage 7400 can interact with an information terminal 7311 or an information terminal 7411, such as a smartphone, possessed by a user through wireless communication.

[0459] The Fig. 23A to Fig. 23G include a housing 9000, a display section 9001, a speaker 9003, an operation button 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (a sensor having a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, a chemical substance, sound, time, hardness, electric field, current, voltage, electric power, radiation, flow rate, humidity, gradient, oscillation, an odor, or infrared rays), a microphone 9008, and the like.

[0460] The Fig. 23A to Fig. The electronic devices illustrated in Fig. 23G have various functions. For example, the electronic devices may have a function of displaying various information (e.g., a still image, a moving image, and a text image) on the display section, a touchscreen function, a function of displaying a calendar, the date, time, and the like, a function of controlling processing using various types of software (programs), a wireless communication function, and a function of reading and processing a program or data stored in a storage medium.

[0461] Below are the Fig. 23A to Fig. 23G are described in detail.

[0462] Fig. 23A is a perspective view of a portable information terminal 9171. For example, the portable information terminal 9171 can be used as a smartphone. The portable information terminal 9171 can include the speaker 9003, the connection terminal 9006, the sensor 9007, or the like. The portable information terminal 9171 can display character and image information on its plurality of surfaces. Fig. 23A illustrates an example in which three icons 9050 are displayed. In addition, information 9051 represented by dashed rectangles may be displayed on another surface of the display section 9001. Examples of the information 9051 include a notification of the arrival of an email, an SNS message, a call, or the like, the subject and sender of an email, an SNS message, or the like, the date, time, the remaining battery power, and the intensity of a radio wave. Alternatively, the icon 9050 or the like may be displayed in the position where the information 9051 is displayed.

[0463] Fig. 23B is a perspective view of a portable information terminal 9172. The portable information terminal 9172 has a function of displaying information on three or more surfaces of the display section 9001. In the example shown here, information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, the user of the portable information terminal 9172 can check the information 9053 displayed so as to be visible from above the portable information terminal 9172, with the portable information terminal 9172 stored in a breast pocket of his / her clothing.

[0464] Fig. 23C is a perspective view of a tablet terminal 9173. The tablet terminal 9173 is suitable for executing various applications, such as mobile phone calls, sending and receiving emails, viewing and editing texts, playing music, Internet communication, and playing computer games. The tablet terminal 9173 includes the display section 9001, the camera 9002, the microphone 9008, and the speaker 9003 on the front of the case 9000, the operation buttons 9005 as buttons for operation on the left side of the case 9000, and the connection port 9006 on the bottom of the case 9000.

[0465] Fig. 23D is a perspective view of a portable information terminal 9200 in the form of a wristwatch. The portable information terminal 9200 can be used, for example, as a smartwatch (registered trademark). The display surface of the display section 9001 is curved, and an image can be displayed on the curved display surface. Further, for example, mutual communication can be performed between the portable information terminal 9200 and a headset capable of wireless communication, and therefore, hands-free phone calls are possible. The portable information terminal 9200 can perform mutual data transmission with another information terminal and charging using the connection port 9006. Note that charging can be performed by wireless power supply.

[0466] Fig. 23E to Fig. 23G are perspective views of a foldable portable information terminal 9201. Fig. Fig. 23E is a perspective view illustrating the portable information terminal 9201 being unfolded. Fig. Fig. 23G is a perspective view illustrating the portable information terminal 9201 being folded. Fig. Fig. 23F is a perspective view illustrating the portable information terminal 9201 from one of the states in Fig. 23E and Fig. 23G is transferred to the other. The portable information terminal 9201 is highly portable when folded. When the portable information terminal 9201 is unfolded, a seamless large display area is highly searchable. The display section 9001 of the portable information terminal 9201 is supported by three housings 9000 connected to each other by hinges 9055. For example, the display section 9001 can be folded with a radius of curvature greater than or equal to 0.1 mm and less than or equal to 150 mm.

[0467] This embodiment can be appropriately combined with other embodiments or examples. In the case where a plurality of structural examples are shown in one embodiment in this specification, the structural examples can be combined as needed. [Example 1]

[0468] In this example, specific manufacturing methods and characteristics of a light-emitting device R1, a light-emitting device G1, and a light-emitting device B1, which are light-emitting devices of one embodiment of the present invention, as well as a comparative light-emitting device R1, a comparative light-emitting device G1, and a comparative light-emitting device B1, which are comparative light-emitting devices, are described. Structural formulas of main compounds used in this example are shown below. (Manufacturing method of the light-emitting device R1)

[0469] First, 100 nm thick silver (Ag) and 85 nm thick indium tin oxide containing silicon oxide (ITSO) were sequentially deposited as a reflective electrode and a transparent electrode, respectively, on a glass substrate from the substrate side by a sputtering method, thereby forming the first electrode 101 with a size of 2 mm × 2 mm. Note that the transparent electrode serves as the anode, and the transparent electrode and the reflective electrode are collectively considered the first electrode 101.

[0470] Next, in a pretreatment for fabricating the light-emitting device over the substrate, the surface of the substrate was washed with water, and baking was performed at 200 °C for one hour.

[0471] The substrate was then transferred to a vacuum evaporation device where the pressure was increased to approximately 1 × 10 -4Pa, and was subjected to vacuum baking for 30 minutes at 170 °C in a heating chamber of the vacuum evaporation device, and then the substrate was cooled for approximately 30 minutes.

[0472] Next, the substrate provided with the first electrode 101 was attached to a substrate holder in the vacuum evaporation apparatus such that the surface on which the first electrode 101 was formed faced downward. Then, N-(biphenyl-2-yl)-N-(9,9-dimethylfluoren-2-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: oFBiSF(2)), represented by the above structural formula (i), and a fluorine-containing material having an electron-accepting property and a molecular weight of 672 (OCHD-003) were co-evaporated to a thickness of 10 nm over the first electrode 101 such that the weight ratio of oFBiSF(2) to OCHD-003 was 1:0.03, thereby forming the hole-injection layer 111.

[0473] Over the hole injection layer 111, oFBiSF(2) was deposited by evaporation to a thickness of 150 nm, forming the first hole transport layer.

[0474] Next, 11-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 11mDBtBPPnfpr), represented by the above structural formula (ii), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), represented by the above structural formula (iii), and a red phosphorescent material OCPG-006 were deposited over the first hole-transporting layer by co-evaporation to a thickness of 40 nm such that the weight ratio of 11mDBtBPPnfpr to PCBBiF and OCPG-006 was 0.7:0.3:0.05 was formed, forming the first light-emitting layer.

[0475] Next, 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), represented by the above structural formula (iv), was deposited by evaporation to a thickness of 10 nm, thereby forming the first electron-transport layer.

[0476] After the first electron-transport layer was formed, 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), represented by the above structural formula (v), as a second organic compound having a phenanthroline framework, and lithium oxide (Li2O) were co-evaporated to a thickness of 5 nm such that the weight ratio of mPPhen2P to Li2O was 1:0.02, thereby forming the first layer. Then, copper phthalocyanine (abbreviation: CuPc), represented by the above structural formula (vii), was co-evaporated to a thickness of 2 nm, thereby forming the third layer. Furthermore, oFBiSF(2) and OCHD-003 were co-evaporated to a thickness of 10 nm in such a way that the weight ratio of oFBiSF(2) to OCHD-003 was 1:0.15, forming the second layer. The intermediate layer was thus formed.

[0477] Over the intermediate layer, oFBiSF(2) was deposited by evaporation to a thickness of 65 nm, forming the second hole transport layer.

[0478] Over the second hole transport layer, 11mDBtBPPnfpr, PCBBiF and OCPG-006 were co-evaporated to a thickness of 40 nm such that the weight ratio of 11mDBtBPPnfpr to PCBBiF and OCPG-006 was 0.7:0.3:0.05, thereby forming the second light-emitting layer.

[0479] Then, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), represented by the above structural formula (viii), was deposited to a thickness of 10 nm, and then 2,2'-[1,2-naphthalenediyl di(4,1-phenylene)]bis(4,6-diphenyl-1,3,5-triazine) (abbreviation: TznP2N), represented by the above structural formula (ix), and 8-hydroxyquinolinato lithium (abbreviation: Liq), represented by the above structural formula (x), were deposited by co-evaporation to a thickness of 25 nm such that the weight ratio of TznP2N to Liq was 1:1, thereby forming the second electron-transport layer was trained.

[0480] Then, Liq was deposited by evaporation to a thickness of 1 nm, and silver (Ag) and magnesium (Mg) were co-evaporated to a thickness of 15 nm such that the volume ratio of Ag to Mg was 1:0.1, thereby forming the second electrode 102. Over the second electrode 102, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), represented by the above structural formula (xi), was deposited to a thickness of 70 nm as a cap layer to improve the light extraction efficiency.

[0481] Next, the light-emitting device was sealed using a glass substrate in a nitrogen-filled glove box so that it was not exposed to air. Specifically, a UV-curing sealing material was applied to enclose the device, only the sealing material was irradiated with UV light, while the light-emitting device was not irradiated with UV light, and a heat treatment was performed at 80°C under atmospheric pressure for one hour. Thus, the light-emitting device R1 was fabricated. (Manufacturing method of the comparative light-emitting device R1)

[0482] The comparative light-emitting device R1 was fabricated in a similar manner to that of the light-emitting device R1, except that the thickness of the second hole-transport layer was changed to 75 nm and the second electron-transport layer was deposited by co-evaporating 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm) represented by the above structural formula (xii) and Liq to a thickness of 25 nm such that the weight ratio of 6BP-4Cz2PPm to Liq was 1:1. (Manufacturing method of the light-emitting device G1)

[0483] The light-emitting device G1 was manufactured in a similar manner to that of the light-emitting device R1, except that the thickness of the first hole-transporting layer was changed to 80 nm, the thickness of the second hole-transporting layer was changed to 50 nm, and the first light-emitting layer and the second light-emitting layer were each deposited by co-evaporating 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) represented by the above structural formula (xii) and 9,10-diphenyl-2-[N-phenyl-N-(9-phenyl-carbazol-3-yl)-amino]-anthracene (abbreviation: 2PCAPA) represented by the above structural formula (xiii) such that the weight ratio of cgDBCzPA to 2PCAPA was 1:0.05. (Manufacturing method of comparative light-emitting device G1)

[0484] The comparative light-emitting device G1 was fabricated in a similar manner to that of the light-emitting device G1, except that the thickness of the second hole-transport layer was changed to 60 nm and the second electron-transport layer was deposited by co-evaporation of 6BP-4Cz2PPm and Liq to a thickness of 25 nm such that the weight ratio of 6BP-4Cz2PPm to Liq was 1:1. (Manufacturing method of light-emitting device B1)

[0485] The light-emitting device B1 was manufactured in a similar manner to that of the light-emitting device R1, except that the thickness of the first hole-transporting layer was changed to 45 nm, the thickness of the second hole-transporting layer was changed to 45 nm, and the first light-emitting layer and the second light-emitting layer were each formed by co-evaporating 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) represented by the above structural formula (xiv) and N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02) represented by the above structural formula (xv). were deposited in a thickness of 25 nm such that the weight ratio of αN-βNPAnth to 3,10PCA2Nbf(IV)-02 was 1:0.015. (Manufacturing method of comparative light-emitting device B1)

[0486] The comparative light-emitting device B1 was fabricated in a similar manner to that of the light-emitting device B1, except that the thickness of the second hole-transport layer was changed to 55 nm and the second electron-transport layer was deposited by co-evaporation of 6BP-4Cz2PPm and Liq to a thickness of 25 nm such that the weight ratio of 6BP-4Cz2PPm to Liq was 1:1.

[0487] The device structures of the light-emitting device R1, the light-emitting device G1, the light-emitting device B1, the comparative light-emitting device R1, the comparative light-emitting device G1, and the comparative light-emitting device B1 are shown below. [Table 1] Dicke (nm) Licht emittierende Vorrichtung R1 Licht emittierende Vergleichsvorrichtung R1 Cap-Schicht 70 DBT3P-II zweite Elektrode 2 15 Ag : Mg (1 : 0.1) 1 1 Liq second electron transport layer b 25 TznP2N : Liq (1 : 1) 6BP-4Cz2PPm : Liq (1 : 1) a 10 mFBPTzn - second light-emitting layer 40 11mDBtBPPnfpr : PCBBiF : OCPG-006 (0.7 : 0.3 : 0.05) second hole transport layer - oFBiSF(2) 65 nm 75 nm Intermediate layer second layer 10 oFBiSF(2) : OCHD-003 (1 : 0.15) third layer 2 CuPc first layer 5 mPPhen2P : Li2O (1 : 0.02) first electron transport layer 10 mPCCzPTzn-02 first light-emitting layer 40 11mDBtBPPnfpr : PCBBiF : OCPG-006 (0.7 : 0.3 : 0.05) first hole transport layer 150 oFBiSF(2) first hole injection layer 10 oFBiSF(2) : OCHD-003 (1 : 0.03) first electrode 2 85 ITSO 1 100 Ag [Table 2] Thickness i (nm) Light-emitting device G1 Light-emitting comparison device G1 Cap layer 70 DBT3P-II second electrode 2 15 Ag : Mg (1 : 0.1) 1 1 Liq second electron transport layer b 25 TznP2N : Liq (1 : 1) 6BP-4Cz2PPm : Liq (1 : 1) a 10 mFBPTzn - second light-emitting layer 40 cgDBCzPA : 2PCAPA (1 : 0.05) second hole transport layer oFBiSF(2) 50 nm 60 nm Intermediate layer second layer 10 oFBiSF(2) : OCHD-003 (1 : 0.15) third layer 2 CuPc first layer 5 mPPhen2P : Li2O (1 : 0.02) first electron transport layer 10 mPCCzPTzn-02 first light-emitting layer 40 cgDBCzPA : 2PCAPA (1 : 0.05) first hole transport layer 80 oFBiSF(2) first hole injection layer 10 oFBiSF(2) : OCHD-003 (1 : 0.03) first electrode 2 i 85 ITSO 1 100 Ag [Table 3] Thickness (nm) Light-emitting device B1 Light-emitting comparison device B1 Cap layer 70 DBT3P-II second electrode 2 15 Ag : Mg (1 : 0.1) 1 1 Liq second electron transport layer b 25 TznP2N : Liq (1 : 1) 6BP-4Cz2PPm : Liq (1 : 1) a ! mFBPTzn - second light-emitting layer 25 αN-βNPAnth: 3.10PCA2Nbf(IV)-02 (1:0.015) second hole transport layer - oFBiSF(2) 45 nm 55 nm Intermediate layer second layer 10 oFBiSF(2) : OCHD-003 (1 : 0.15) third layer 2 CuPc first layer 5 mPPhen2P : Li2O (1 : 0.02) first electron transport layer 10 mPCCzPTzn-02 first light-emitting layer 25 αN-βNPAnth: 3.10PCA2Nbf(IV)-02 (1:0.015) first hole transport layer 45 oFBiSF(2) first hole injection layer 10 oFBiSF(2) : OCHD-003 (1 : 0.03) first electrode 2 85 ITSO 1 100 Ag

[0488] Fig. 24, Fig. 25, Fig. 26 and Fig. 27 show the current density-voltage characteristics, the current efficiency-luminance characteristics, the power efficiency-luminance characteristics, and the electroluminescence spectra of the light-emitting device R1 and the comparative light-emitting device R1, respectively. Fig. 28, Fig. 29, Fig. 30 and Fig. 31 show the current density-voltage characteristics, the current efficiency-luminance characteristics, the power efficiency-luminance characteristics, and the electroluminescence spectra of the light-emitting device G1 and the comparative light-emitting device G1, respectively. Fig. 32, Fig. 33, Fig. 34, Fig. 35 and Fig.36 show the current density-voltage characteristics, the current efficiency-luminance characteristics, the blue index-luminance characteristics, the power efficiency-luminance characteristics, and the electroluminescence spectra of the light-emitting device B1 and the comparative light-emitting device B1, respectively.

[0489] Note that the blue index (BI) is a value obtained by dividing the current efficiency (cd / A) by the y-value of CIE chromaticity (x, y), and is one of the indicators of the characteristics of blue light emission. There is a tendency that as the y-chromaticity value of blue light emission becomes smaller, its color purity increases. A blue light emission with a small y-chromaticity value and high color purity enables the display of blue colors with a wide range of chromaticity. Using a blue light emission with high color purity reduces the luminance of blue light emission required for a display to display white, resulting in lower power consumption of the display.Therefore, BI, which is a current efficiency based on a y-chromaticity value as one of the indicators of blue color purity, is appropriately used in some cases as a means of representing the efficiency of blue light emission. A light-emitting device with a higher BI can be considered a higher-efficiency blue light-emitting device for a display.

[0490] Table 4 shows the main characteristics of the light-emitting device R1 and the comparative light-emitting device R1 at approximately 1000 cd / m 2 . Table 5 shows those of the light-emitting device G1 and the comparative light-emitting device G1 at about 1000 cd / m 2 . Table 6 shows those of the light-emitting device B1 and the comparative light-emitting device B1 at about 1000 cd / m 2The luminance, CIE chromaticity, and electroluminescence spectra were measured at room temperature using a spectroradiometer (SR-UL1R, TOPCON TECHNOHOUSE CORPORATION). [Table 4] Voltage (V) Current (mA) Current density (mA / cm 2 ) Chromaticity x Chromaticity y Power efficiency (cd / A) Power efficiency (Im / W) Light-emitting device R1 5,20 0,06 1,4 0,69 0,31 56,9 34,4 Light-emitting comparator R1 5,40 0,06 1,6 0,69 0,31 54,5 31,7

[0491] Fig. 24 to Fig.27 and Table 4 revealed that red light emission with a peak wavelength of the electroluminescence spectrum of 625 nm can be obtained from both the light-emitting device R1 and the comparative light-emitting device R1. Although both the light-emitting device R1 and the comparative light-emitting device R1 have high power efficiency, the light-emitting device R1 has lower power consumption, higher power efficiency, and more advantageous characteristics because it has a lower operating voltage than the comparative light-emitting device R1. This indicates that the light-emitting device R1 of one embodiment of the present invention is a tandem light-emitting device with advantageous characteristics. [Table 5] Voltage (V) Current (mA) Current density (mA / cm 2 ) Chromaticity x Chromaticity y Power efficiency (cd / A) Power efficiency (Im / W) Light-emitting device G1 6,00 0,05 1,2 0,21 0,73 58,6 30,7 Light-emitting comparison device G1 6,20 0,06 1,5 0,22 0,72 59,7 30,2

[0492] Fig. 28 to Fig.31 and Table 5 revealed that green light emission with a peak wavelength of the electroluminescence spectrum of 532 nm can be obtained from both the light-emitting device G1 and the comparative light-emitting device G1. Although both the light-emitting device G1 and the comparative light-emitting device G1 have high power efficiency, the light-emitting device G1 has lower power consumption and more advantageous characteristics because it has a lower operating voltage than the comparative light-emitting device G1. This indicates that the light-emitting device G1 of one embodiment of the present invention is a tandem light-emitting device with advantageous characteristics. [Table 6] Voltage (V) Current (mA) Current density (mA / cm 2 ) Chromaticity x Chromaticity y Power efficiency (cd / A) Power efficiency (Im / W) BI (cd / A / y) Light-emitting device B1 7,60 0,52 13,1 0,15 0,04 7,8 3,2 192,6 Light-emitting comparison device B1 8,00 0,43 10,7 0,14 0,05 8,1 3,2 174,9

[0493] Fig. 32 to Fig.36 and Table 6 revealed that blue light emission with peak wavelengths of the electroluminescence spectrum of 454 nm and 457 nm can be obtained from the light-emitting device B1 and the comparative light-emitting device B1. Although both the light-emitting device B1 and the comparative light-emitting device B1 have high power efficiency, the light-emitting device B1 has lower power consumption and more advantageous characteristics because it has a lower operating voltage than the comparative light-emitting device B1. The light-emitting device B1 has a high blue index.This indicates that the light-emitting device B1 of one embodiment of the present invention is a tandem light-emitting device with advantageous properties as a light-emitting device included in a blue subpixel of a display device. Furthermore, the light-emitting device B1 exhibits particularly advantageous properties at a practical luminance of and above 500 cd / cm. 2 on.

[0494] Here, the second electron-transport layers of the light-emitting device R1, the light-emitting device G1, and the light-emitting device B1 contain the same material (the first organic compound having a triazine skeleton). Therefore, the light-emitting devices of different emission colors of one embodiment of the present invention can each exhibit advantageous properties even if the second electron-transport layers of the light-emitting devices are formed of the same material.

[0495] Next, a display device of this example including the light-emitting device R1, the light-emitting device G1, and the light-emitting device B1 in red, green, and blue subpixels, respectively, and a display device of the comparative example including the comparative light-emitting device R1, the comparative light-emitting device G1, and the comparative light-emitting device B1 in red, green, and blue subpixels, respectively, were assumed, and the power consumption of their display sections (excluding the power consumption of a driving transistor, a driving circuit, and the like) was preliminarily calculated.Note that each of the light-emitting devices assumed to be used in both of the display devices is a tandem light-emitting device, and the same emission center substance is used in the plurality of light-emitting layers in each of the light-emitting devices. Therefore, the display devices are side-by-side display devices.

[0496] The conditions of the indicators adopted for the preliminary calculation are as follows. [Table 7] Screen size 5 inches (16:9) Screen area 68,9 cm 2 aperture ratio 30% Red 10% Green 10% Blue 10 % effective luminance 1000 cd / m 2 with the white display on the entire screen circular polarizing plate not used

[0497] First, for each of the display devices, the luminance (effective luminance) of the light-emitting devices of RGB was calculated under the conditions described above, in which a 1000 cd / m 2-Emission of white light with CIE 1931 chromaticity coordinates (x, y) = (0.31, 0.33) is obtained when the display device is made to emit white light from the entire screen.

[0498] Next, the luminance (intrinsic luminance) required to obtain the calculated effective luminance of the RGB light-emitting devices was calculated, taking the aperture ratios into account. The intrinsic luminance is the luminance at which each light-emitting device actually emits light to achieve the effective luminance of 1000 cd / m 2when the display device is made to emit white light with CIE 1931 chromaticity coordinates (x, y) = (0.31, 0.33) from the entire screen. Since the aperture ratio of the entire display device subjected to the preliminary calculation is 30% and the aperture ratio per emission color is 10%, the intrinsic luminance is approximately ten times the effective luminance.

[0499] From the measurement results of the above-described light-emitting devices and the intrinsic luminance, the current density and voltage at which each light-emitting device emits light with the intrinsic luminance can be obtained. In other words, for each of the display devices under the above-described conditions, the current density and voltage of each light-emitting device can be obtained to achieve emission with the luminance of 1000 cd / m2 of white light with CIE 1931 chromaticity coordinates (x, y) = (0.31, 0.33) when the display device is made to emit white light from the entire screen.

[0500] Power consumption is calculated by multiplying the current by the voltage. The current is calculated by multiplying the current density, the screen area, and the aperture ratio. The displays subjected to the preliminary calculation each have a diagonal of 5 inches, an aspect ratio of 16:9, and a screen area of 68.9 cm. 2and an aperture ratio of the light-emitting device of each color of 10%, and the current amount can be calculated by multiplying the current density calculated in the previous paragraph by these values. Furthermore, the power consumption of the light-emitting device of each emission color can be calculated by multiplying the current amount by the voltage obtained in the previous paragraph. By calculating and adding the power consumption of the light-emitting devices of RGB, the total power consumption of the display section of the display device (excluding the power consumption of the drive transistor, the drive circuit, and the like) can be obtained.

[0501] Table 8 shows the calculated power consumption of the display device of this example, assuming the use of the light-emitting device R1, the light-emitting device G1, and the light-emitting device B1, and Table 9 shows the calculated power consumption of the display device of the comparative example, assuming the use of the comparative light-emitting device R1, the comparative light-emitting device G1, and the comparative light-emitting device B1. [Table 8] This example Chromaticity x Chromaticity y effective luminance (cd / m2) intrinsic luminance (cd / m2) Power efficiency (cd / A) Current density (mA / cm 2 ) Current (mA) Voltage (V) Power consumption (mW) Red 0,69 0,31 255 2550 55,1 4,6 31,9 5,78 184,4 Green 0,21 0,73 694 6938 57,6 12,1 83,1 6,88 571,5 Blue 0,15 0,04 51 511 7,9 6,5 44,6 7,33 326,5 total white 0,31 0,33 1000 - 43,2 - 159,6 - 1082,4 [Table 9] Comparison example Chromaticity x Chromaticity y effective luminance (cd / m2) intrinsic luminance (cd / m2) Power efficiency (cd / A) Current density (mA / cm 2 ) Current (mA) Voltage (V) Power consumption (mW) Red 0,69 0,31 252 2517 52,9 4,8 32,8 6,06 198,5 Green 0,21 0,72 689 6893 57,8 11,9 82,1 7,46 612,8 Blue 0,14 0,05 59 590 8,2 7,2 49,4 7,79 384,7 total white 0,31 0,33 1000 - 41,9 - 164,3 - 1196,0

[0502] Table 8 and Table 9 show that the display device of this example has higher power efficiency in white light emission and a lower operating voltage than the display device of the comparative example. Furthermore, the power consumption of the display device of this example is lower than that of the display device of the comparative example.

[0503] Therefore, the display device has advantageous low power consumption characteristics, the display device comprising the tandem light-emitting devices each comprising the second electron-transport layer containing the first organic compound having a triazine skeleton and the intermediate layer comprising the mixed layer of the second organic compound having a phenanthroline skeleton and lithium or a lithium compound, and having a difference between maximum peak wavelengths in emission spectra of the plurality of light-emitting layers of less than or equal to 30 nm.

[0504] This application is based on Japanese Patent Application Serial No. 2023-223545 filed with the Japan Patent Office on December 28, 2023, and Japanese Patent Application Serial No. 2024-035813 filed with the Japan Patent Office on March 8, 2024, the entire contents of which are hereby incorporated by reference. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-161850

[0006] JP 2023-223545

[0504]

Claims

[1] Light-emitting device comprising: a first electrode; a second electrode; an intermediate layer; a first light-emitting layer; a second light-emitting layer; a first electron transport layer; and a second electron transport layer, wherein the intermediate layer is located between the first electrode and the second electrode, wherein the first light-emitting layer is located between the first electrode and the intermediate layer, wherein the second light-emitting layer is located between the intermediate layer and the second electrode, wherein the first electron transport layer is located between the first light-emitting layer and the intermediate layer, wherein the second electron transport layer is located between the second light-emitting layer and the second electrode, wherein the second electron transport layer has a multilayer structure of at least a third electron transport layer and a fourth electron transport layer, wherein the fourth electron transport layer is located between the third electron transport layer and the second electrode, wherein the intermediate layer comprises a mixed layer of a second organic compound and lithium or a lithium compound, wherein the second organic compound has a phenanthroline skeleton, wherein the first light-emitting layer comprises a first emission center substance, wherein the second light-emitting layer comprises a second emission center substance, wherein a difference between a maximum peak wavelength of an emission spectrum of the first emission center substance and a maximum peak wavelength of an emission spectrum of the second emission center substance is less than or equal to 30 nm, and wherein the first light-emitting layer and the second light-emitting layer are light-emitting layers that are different from a light-emitting layer of at least one of a plurality of adjacent light-emitting devices. [2] The light-emitting device according to claim 1, wherein the fourth electron-transport layer comprises a first organic compound having a triazine skeleton. [3] The light-emitting device according to claim 1, wherein the fourth electron transport layer comprises lithium or a lithium compound. [4] The light-emitting device according to claim 1, wherein the first emission center substance is the same substance as the second emission center substance. [5] The light-emitting device according to claim 1, wherein the intermediate layer comprises a first layer comprising the second organic compound. [6] Light-emitting device according to claim 5, wherein the intermediate layer further comprises a second layer, and wherein the second layer is located between the first layer and the second light-emitting layer. [7] The light-emitting device according to claim 6, wherein the second layer comprises a fourth organic compound having a hole transport property. [8] The light-emitting device according to claim 7, wherein the second layer comprises an organic compound having a halogen group and / or a cyano group. [9] Light-emitting device according to claim 1, wherein the first electron transport layer has a multilayer structure of at least a fifth electron transport layer and a sixth electron transport layer, and wherein the sixth electron transport layer is located between the fifth electron transport layer and the intermediate layer. [10] The light-emitting device according to claim 9, wherein the sixth electron-transport layer comprises a third organic compound having a triazine skeleton. [11] Light-emitting device comprising: a first electrode; a second electrode; an intermediate layer; a first light-emitting layer; a second light-emitting layer; a first electron transport layer; and a second electron transport layer, wherein the intermediate layer is located between the first electrode and the second electrode, wherein the first light-emitting layer is located between the first electrode and the intermediate layer, wherein the second light-emitting layer is located between the intermediate layer and the second electrode, wherein the first electron transport layer is located between the first light-emitting layer and the intermediate layer, wherein the second electron transport layer is located between the second light-emitting layer and the second electrode, wherein the second electron transport layer has a multilayer structure of at least a third electron transport layer and a fourth electron transport layer, wherein the fourth electron transport layer is located between the third electron transport layer and the second electrode, wherein the fourth electron transport layer comprises a first organic compound having a triazine skeleton, wherein the first electron transport layer comprises a third organic compound having a triazine skeleton, wherein the intermediate layer comprises a second organic compound having a phenanthroline skeleton, wherein the first light-emitting layer comprises a first emission center substance, wherein the second light-emitting layer comprises a second emission center substance, wherein a difference between a maximum peak wavelength of an emission spectrum of the first emission center substance and a maximum peak wavelength of an emission spectrum of the second emission center substance is less than or equal to 30 nm, and wherein the first light-emitting layer and the second light-emitting layer are light-emitting layers that are different from a light-emitting layer of at least one of a plurality of adjacent light-emitting devices. [12] The light-emitting device according to claim 11, wherein the first organic compound is the same organic compound as the third organic compound. [13] The light-emitting device of claim 11, wherein the intermediate layer comprises lithium or a lithium compound. [14] The light-emitting device according to claim 13, wherein the intermediate layer comprises a mixed layer of the second organic compound and the lithium or the lithium compound. [15] The light-emitting device according to claim 11, wherein the fourth electron transport layer comprises lithium or a lithium compound. [16] The light-emitting device according to claim 11, wherein the first emission center substance is the same substance as the second emission center substance. [17] The light-emitting device according to claim 11, wherein the intermediate layer comprises a first layer comprising the second organic compound. [18] Light-emitting device according to claim 17, wherein the intermediate layer further comprises a second layer, and wherein the second layer is located between the first layer and the second light-emitting layer. [19] The light-emitting device according to claim 18, wherein the second layer comprises a fourth organic compound having a hole transport property. [20] The light-emitting device according to claim 19, wherein the second layer comprises an organic compound comprising a halogen group and / or a cyano group. [21] Light-emitting device according to claim 11, wherein the first electron transport layer has a multilayer structure of at least a fifth electron transport layer and a sixth electron transport layer, and wherein the sixth electron transport layer is located between the fifth electron transport layer and the intermediate layer. [22] The light-emitting device according to claim 21, wherein the sixth electron-transport layer comprises a third organic compound having a triazine skeleton. [23] Display device comprising: a first light-emitting device; and a second light-emitting device, wherein the first light-emitting device is adjacent to the second light-emitting device, wherein the first light-emitting device comprises: a first electrode; a second electrode; a first intermediate layer; a first light-emitting layer; a second light-emitting layer; a first electron transport layer; and a second electron transport layer, wherein the first intermediate layer is located between the first electrode and the second electrode, wherein the first light-emitting layer is located between the first electrode and the first intermediate layer, wherein the second light-emitting layer is located between the first intermediate layer and the second electrode, wherein the first electron transport layer is located between the first light-emitting layer and the first intermediate layer, wherein the second electron transport layer is located between the second light-emitting layer and the second electrode, wherein the second electron transport layer has a multilayer structure of at least a third electron transport layer and a fourth electron transport layer, wherein the fourth electron transport layer is located between the third electron transport layer and the second electrode, wherein the second light-emitting device comprises: a third electrode; a fourth electrode; a second intermediate layer; a third light-emitting layer; a fourth light-emitting layer; a fifth electron transport layer; and a sixth electron transport layer, wherein the second intermediate layer is located between the third electrode and the fourth electrode, wherein the third light-emitting layer is located between the third electrode and the second intermediate layer, wherein the fourth light-emitting layer is located between the second intermediate layer and the fourth electrode, wherein the fifth electron transport layer is located between the third light-emitting layer and the second intermediate layer, wherein the sixth electron transport layer is located between the fourth light-emitting layer and the fourth electrode, wherein the sixth electron transport layer has a multilayer structure of at least a seventh electron transport layer and an eighth electron transport layer, wherein the eighth electron transport layer is located between the seventh electron transport layer and the fourth electrode, wherein the fourth electron transport layer and the eighth electron transport layer are formed of the same material, wherein the first intermediate layer and the second intermediate layer each comprise a second organic compound and lithium or a lithium compound, wherein the second organic compound has a phenanthroline skeleton, wherein the first light-emitting layer comprises a first emission center substance, wherein the second light-emitting layer comprises a second emission center substance, wherein the third light-emitting layer comprises a third emission center substance, wherein the fourth light-emitting layer comprises a fourth emission center substance, wherein a difference between a maximum peak wavelength of an emission spectrum of the first emission center substance and a maximum peak wavelength of an emission spectrum of the second emission center substance is less than or equal to 30 nm, wherein a difference between a maximum peak wavelength of an emission spectrum of the third emission center substance and a maximum peak wavelength of an emission spectrum of the fourth emission center substance is less than or equal to 30 nm, wherein the first light-emitting layer is a light-emitting layer different from the third light-emitting layer, and wherein the second light-emitting layer is a light-emitting layer different from the fourth light-emitting layer. [24] The display device according to claim 23, wherein the second electron transport layer and the sixth electron transport layer are a continuous layer.

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