Light emitting device, light emitting apparatus, electronic equipment, display apparatus, and lighting apparatus

Abstract

The present invention provides a novel light emitting device that has excellent convenience, usefulness and reliability. This light emitting device has a first electrode, a second electrode, and a first layer, wherein the first layer is positioned between the first electrode and the second electrode, and the first layer includes a light emitting material, a first organic compound, and a first material. The light emitting material is provided with a function of emitting fluorescence, and is provided with an end part positioned at a longest wavelength of an absorption spectrum at a first wavelength. The first organic compound is provided with a function of converting triplet excitation energy into light emission, and the light emission is provided with an end part positioned at a shortest wavelength of the spectrum at a second wavelength, the second wavelength being positioned at a shorter wavelength than the first wavelength. In addition, the first organic compound is provided with a first substituent R1, the first substituent R1 being any of an alkyl group, a cycloalkyl group, or a trialkylsilyl group. The first material is provided with a function of emitting delayed fluorescence at room temperature, the difference between a HOMO level and a LUMO level of the first material being smaller than that of the first organic compound.

Description

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

[0001] One embodiment of the present invention relates to a light-emitting device, an electronic device, a display device, a lighting device, or a semiconductor device.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Therefore, more specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, a driving method thereof, or a manufacturing method thereof.

[0003] In recent years, research and development of light-emitting devices that utilize electroluminescence (EL) has been actively conducted. The basic configuration of these light-emitting devices is a layer containing a light-emitting substance (EL layer) sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this light-emitting device, light is emitted from the light-emitting substance.

[0004] Since the above-mentioned light-emitting device is a self-luminous type, a display device using the same has advantages such as excellent visibility, no need for a backlight, low power consumption, etc. Furthermore, it can be manufactured to be thin and lightweight, and has advantages such as a high response speed.

[0005] In the case of a light-emitting device (e.g., an organic EL element) that uses an organic compound as a light-emitting substance and has an EL layer containing the light-emitting organic compound between a pair of electrodes, applying a voltage between the pair of electrodes causes electrons from the cathode and holes from the anode to be injected into the light-emitting EL layer, respectively, causing a current to flow. The injected electrons and holes are then recombined, causing the light-emitting organic compound to enter an excited state, and light can be emitted from the excited light-emitting organic compound.

[0006] The types of excited states that organic compounds form include singlet excited states (S ＊ ) and triplet excited states (T＊ ) and light emission from the singlet excited state is called fluorescence, and light emission from the triplet excited state is called phosphorescence. The statistical generation ratio of these in a light-emitting device is S ＊ : T ＊ = 1:3. Therefore, light-emitting devices using phosphorescent compounds (phosphorescent materials) can achieve higher luminous efficiency than light-emitting devices using fluorescent compounds (fluorescent materials). Therefore, in recent years, there has been active development of light-emitting devices using phosphorescent materials that can convert the energy of triplet excited states into luminescence.

[0007] Among light-emitting devices using phosphorescent materials, particularly those that emit blue light, the development of stable compounds with high triplet excitation energy levels has been difficult, and thus no practical applications have been achieved. Therefore, light-emitting devices using more stable fluorescent materials have been developed, and methods for improving the luminous efficiency of light-emitting devices using fluorescent materials (fluorescent light-emitting devices) have been explored.

[0008] In addition to phosphorescent materials, thermally activated delayed fluorescence (TADF) materials are known as materials capable of converting part or all of the energy of a triplet excited state into luminescence. In thermally activated delayed fluorescence materials, a singlet excited state is generated from the triplet excited state by reverse intersystem crossing, and the energy of the singlet excited state is converted into luminescence.

[0009] In order to improve the luminous efficiency of a light-emitting device using a thermally activated delayed fluorescent material, it is important that the thermally activated delayed fluorescent material not only efficiently generates a singlet excited state from a triplet excited state but also efficiently emits light from the singlet excited state, i.e., has a high fluorescence quantum yield. However, it is difficult to design a light-emitting material that satisfies both of these requirements simultaneously.

[0010] Furthermore, in a light-emitting device having a thermally activated delayed fluorescent material and a fluorescent material, a method has been proposed in which the singlet excitation energy of the thermally activated delayed fluorescent material is transferred to the fluorescent material, thereby obtaining light emission from the fluorescent material (see Patent Document 1).

[0011] Also known is a light-emitting device containing a host material and a guest material in the light-emitting layer (see Patent Document 2). The host material has the function of converting triplet excitation energy into luminescence, and the guest material emits fluorescence. The molecular structure of the guest material has a luminophore and a protecting group, and five or more protecting groups are contained in one molecule of the guest material. Introducing the protecting group into the molecule can suppress the transfer of triplet excitation energy from the host material to the guest material by the Dexter mechanism. Note that an alkyl group or a branched-chain alkyl group can be used as the protecting group.

[0012] JP 2014-45179 A International Publication No. 2019 / 171197 Pamphlet

[0013] An object of one embodiment of the present invention is to provide a novel light-emitting device with excellent convenience, usefulness, or reliability.An object of one embodiment of the present invention is to provide a novel electronic device with excellent convenience, usefulness, or reliability.An object of one embodiment of the present invention is to provide a novel display device with excellent convenience, usefulness, or reliability.An object of one embodiment of the present invention is to provide a novel lighting device with excellent convenience, usefulness, or reliability.An object of one embodiment of the present invention is to provide a novel light-emitting device, a novel light-emitting device, a novel electronic device, a novel display device, a novel lighting device, or a novel semiconductor device.

[0014] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these will become apparent from the description of the specification, drawings, claims, etc., and it is possible to extract other problems from the description of the specification, drawings, claims, etc.

[0015] (1) One embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, and a first layer.

[0016] The second electrode has an area overlapping with the first electrode, and the first layer is located between the first electrode and the second electrode, and the first layer includes a light-emitting material FM, a first organic compound, and a first material.

[0017] The luminescent material FM has a function of emitting fluorescence, and the luminescent material FM has an end portion located at the longest wavelength of the absorption spectrum at a first wavelength λ abs (nm).

[0018] The first organic compound has a function of converting triplet excitation energy into luminescence, and the luminescence of the first organic compound has an edge located at the shortest wavelength of the spectrum at a second wavelength λp (nm), and the second wavelength λp is located at a wavelength shorter than the first wavelength λabs.

[0019] The first organic compound also has a first substituent R １ and the first substituent R １ is either an alkyl group, a substituted or unsubstituted cycloalkyl group, or a trialkylsilyl group, wherein the alkyl group has 3 to 12 carbon atoms, the cycloalkyl group has 3 to 10 carbon atoms forming a ring, and the trialkylsilyl group has 3 to 12 carbon atoms.

[0020] The first material has the function of emitting delayed fluorescence at room temperature.

[0021] (2) Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, and a first layer.

[0022] The second electrode has an area overlapping with the first electrode, and the first layer is located between the first electrode and the second electrode, and the first layer includes a light-emitting material FM, a first organic compound, and a first material.

[0023] The luminescent material FM has a function of emitting fluorescence, and the luminescent material FM has an end portion located at the longest wavelength of the absorption spectrum at a first wavelength λ abs (nm).

[0024] The first organic compound has a function of converting triplet excitation energy into luminescence, and the luminescence of the first organic compound has an edge located at the shortest wavelength of the spectrum at a second wavelength λp (nm), and the second wavelength λp is located at a wavelength shorter than the first wavelength λabs.

[0025] The first organic compound also has a first substituent R １ and the first substituent R １ is a substituted or unsubstituted alkyl group, cycloalkyl group, or trialkylsilyl group. The alkyl group has 3 to 12 carbon atoms, the cycloalkyl group has 3 to 10 carbon atoms forming a ring, and the trialkylsilyl group has 3 to 12 carbon atoms.

[0026] The first material is composed of a second organic compound and a third organic compound, and the second organic compound and the third organic compound form an exciplex.

[0027] (3) Another embodiment of the present invention is the light-emitting device described above, in which the first organic compound has a first HOMO level HOMO1 and a first LUMO level LUMO1, and the first material has a second HOMO level HOMO2 and a second LUMO level LUMO2.

[0028] The first HOMO level HOMO1, the first LUMO level LUMO1, the second HOMO level HOMO2, and the second LUMO level LUMO2 satisfy the following formula (1).

[0029]

[0030] This allows the first organic compound to be used as the energy donor material ED, and allows the energy of the energy donor material ED, particularly the energy of the triplet excited state, to be transferred to the light-emitting material FM. In addition, the energy donor material ED has a first substituent R １ sandwiched therebetween. In addition, the center-to-center distance between the energy donor material ED and the adjacent light-emitting material FM can be made appropriate. In addition, energy transfer by the Dexter mechanism can be suppressed. In addition, energy transfer by the Förster mechanism can be made dominant. In addition, the light-emitting material FM can be brought into a singlet excited state. In addition, the probability of generating the singlet excited state of the light-emitting material FM can be increased. In addition, the light-emitting efficiency can be increased.

[0031] Furthermore, triplet excitons generated in the first material can be converted into singlet excitons. Furthermore, the difference between the HOMO level and the LUMO level of the first material can be made smaller than the difference between the HOMO level and the LUMO level of the first organic compound, thereby increasing the carriers moving through the first material. Furthermore, the recombination probability of carriers in the first material can be increased. Furthermore, energy can be transferred from excitons generated in the first material to the energy donor material ED. Furthermore, excitons can be generated in the first material, and the energy of the excitons can be transferred to the light-emitting material FM via the energy donor material ED. Furthermore, the light-emitting material FM can be brought into a singlet excited state. Furthermore, the probability of generating a singlet excited state of the light-emitting material FM can be increased. Furthermore, the light-emitting efficiency can be increased. As a result, a novel light-emitting device with excellent convenience, usefulness, and reliability can be provided.

[0032] This can increase the number of carriers moving through the first material. It can also increase the recombination probability of carriers in the first material. It can also transfer energy from excitons generated in the first material to the energy donor material ED. It can also generate excitons in the first material, and transfer the energy of the excitons to the light-emitting material FM via the energy donor material ED. It can also place the light-emitting material FM in a singlet excited state. It can also increase the probability of generating a singlet excited state in the light-emitting material FM. It can also increase the light-emitting efficiency. As a result, it is possible to provide a novel light-emitting device that is highly convenient, useful, and reliable.

[0033] (4) In another embodiment of the present invention, the light-emitting material FM is a second substituent R ２ and the second substituent R ２ is any one of a methyl group, a branched alkyl group, a substituted or unsubstituted cycloalkyl group, and a trialkylsilyl group.

[0034] The branched alkyl group has 3 to 12 carbon atoms, the cycloalkyl group has 3 to 10 carbon atoms forming the ring, and the trialkylsilyl group has 3 to 12 carbon atoms.

[0035] (5) In another embodiment of the present invention, the light-emitting material FM has 5 or more second substituents R ２ and five or more second substituents R ２ At least five second substituents R ２ and each independently represent a branched alkyl group, a substituted or unsubstituted cycloalkyl group, or a trialkylsilyl group.

[0036] The branched alkyl group has 3 to 12 carbon atoms, the cycloalkyl group has 3 to 10 carbon atoms forming the ring, and the trialkylsilyl group has 3 to 12 carbon atoms.

[0037] As a result, the light-emitting material FM has a second substituent R ２ sandwiched therebetween. In addition, the center-to-center distance between the energy donor material ED and the adjacent light-emitting material FM can be made appropriate. In addition, energy transfer by the Dexter mechanism can be suppressed. In addition, energy transfer by the Förster mechanism can be made dominant. In addition, the light-emitting material FM can be brought into a singlet excited state. In addition, the probability of generating the singlet excited state of the light-emitting material FM can be increased. In addition, the light-emitting efficiency can be increased. As a result, a novel light-emitting device excellent in convenience, usefulness, and reliability can be provided.

[0038] (6) Another embodiment of the present invention is the light-emitting device, wherein the light-emitting material FM has a third LUMO level LUMO3, which is higher than the second LUMO level LUMO2.

[0039] (7) Another embodiment of the present invention is the above light-emitting device, in which the second HOMO level HOMO2 is higher than the first HOMO level HOMO1 and the second LUMO level LUMO2 is lower than the first LUMO level LUMO1.

[0040] This can suppress electron capture by the light-emitting material FM. It can also suppress the probability of carrier recombination in the light-emitting material FM. It can also suppress the phenomenon of the light-emitting material FM being in a triplet excited state due to carrier recombination in the light-emitting material FM. It can also generate excitons in the first material, and transfer the energy of the excitons to the light-emitting material FM via the energy donor material ED. It can also increase the probability of generating a singlet excited state in the light-emitting material FM. It can also increase the luminous efficiency. As a result, it is possible to provide a novel light-emitting device that is highly convenient, useful, and reliable.

[0041] (8) Another embodiment of the present invention is the above light-emitting device, in which the first HOMO level HOMO1 is higher than the second HOMO level HOMO2.

[0042] This allows the organometallic complex to easily capture holes. Also, the recombination probability of carriers in the organometallic complex can be increased. Furthermore, by using the organometallic complex as the energy donor material ED, the energy of the energy donor material ED, particularly the energy of the triplet excited state, can be transferred to the light-emitting material FM. Furthermore, the energy donor material ED has a first substituent R １ sandwiched therebetween. In addition, the center-to-center distance between the energy donor material ED and the adjacent light-emitting material FM can be made appropriate. In addition, energy transfer by the Dexter mechanism can be suppressed. In addition, energy transfer by the Förster mechanism can be made dominant. In addition, the light-emitting material FM can be brought into a singlet excited state. In addition, the probability of generating the singlet excited state of the light-emitting material FM can be increased. In addition, the light-emitting efficiency can be increased. As a result, a novel light-emitting device excellent in convenience, usefulness, and reliability can be provided.

[0043] (9) Another embodiment of the present invention is the above light-emitting device, in which the first LUMO level LUMO1 is lower than the second LUMO level LUMO2.

[0044] This allows the organometallic complex to easily capture electrons. Also, the probability of carrier recombination in the organometallic complex can be increased. Furthermore, by using the organometallic complex as the energy donor material ED, the energy of the energy donor material ED, particularly the energy of the triplet excited state, can be transferred to the light-emitting material FM. Furthermore, the energy donor material ED has a first substituent R between it and the adjacent light-emitting material FM. １ sandwiched therebetween. In addition, the center-to-center distance between the energy donor material ED and the adjacent light-emitting material FM can be made appropriate. In addition, energy transfer by the Dexter mechanism can be suppressed. In addition, energy transfer by the Förster mechanism can be made dominant. In addition, the light-emitting material FM can be brought into a singlet excited state. In addition, the probability of generating the singlet excited state of the light-emitting material FM can be increased. In addition, the light-emitting efficiency can be increased. As a result, a novel light-emitting device excellent in convenience, usefulness, and reliability can be provided.

[0045] (10) Another embodiment of the present invention is a light-emitting device including the above-described light-emitting device and a transistor or a substrate.

[0046] (11) Another embodiment of the present invention is a display device including the above-described light-emitting device and a transistor or a substrate.

[0047] (12) Another embodiment of the present invention is a lighting device including the above-described light-emitting device and a housing.

[0048] (13) Another embodiment of the present invention is an electronic device including the above display device, a sensor, an operation button, a speaker, or a microphone.

[0049] In the drawings accompanying this specification, components are classified by function and shown as independent blocks in block diagrams, but in reality, it is difficult to completely separate components by function, and one component may be involved in multiple functions.

[0050] In this specification, the term "light-emitting device" includes an image display device using a light-emitting device. The term "light-emitting device" may also include a module in which a connector, such as an anisotropic conductive film or a TCP (Tape Carrier Package), is attached to a light-emitting device, a module in which a printed wiring board is provided at the end of a TCP, or a module in which an IC (integrated circuit) is directly mounted on a light-emitting device using a COG (Chip On Glass) method. Furthermore, a lighting device or the like may have a light-emitting device.

[0051] According to one embodiment of the present invention, a novel light-emitting device with excellent convenience, usefulness, or reliability can be provided. Alternatively, a novel electronic device with excellent convenience, usefulness, or reliability can be provided. Alternatively, a novel display device with excellent convenience, usefulness, or reliability can be provided. Alternatively, a novel light-emitting device, a novel light-emitting device, a novel electronic device, a novel display device, a novel lighting device, or a novel semiconductor device can be provided.

[0052] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc.

[0053] FIGS. 1A to 1E are diagrams illustrating a configuration of a light-emitting device according to an embodiment. FIGS. 2A to 2C are diagrams illustrating a configuration of a light-emitting device according to an embodiment. FIGS. 3A and 3B are diagrams illustrating a configuration of a light-emitting device according to an embodiment. FIGS. 4A and 4B are diagrams illustrating a configuration of a functional panel according to an embodiment. FIGS. 5A to 5C are diagrams illustrating a configuration of a functional panel according to an embodiment. FIGS. 6A and 6B are conceptual diagrams of an active matrix light-emitting device. FIGS. 7A and 7B are conceptual diagrams of an active matrix light-emitting device. FIG. 8 is a conceptual diagram of an active matrix light-emitting device. FIGS. 9A and 9B are conceptual diagrams of a passive matrix light-emitting device. FIGS. 10A and 10B are diagrams illustrating a lighting device. FIGS. 11A to 11D are diagrams illustrating electronic devices. FIGS. 12A to 12C are diagrams illustrating electronic devices. FIG. 13 is a diagram illustrating a lighting device. FIG. 14 is a diagram illustrating a lighting device. FIG. 15 is a diagram illustrating an in-vehicle display device and a lighting device. FIGS. 16A to 16C are diagrams illustrating electronic devices. 17A to 17C are diagrams illustrating the configuration of a light-emitting device according to an example. FIG. 18 is a diagram illustrating the absorption spectrum and emission spectrum of a material used in a light-emitting device according to an example. FIG. 19 is a diagram illustrating the absorption spectrum and emission spectrum of a material used in a light-emitting device according to an example. FIG. 20 is a diagram illustrating the absorption spectrum and emission spectrum of a material used in a light-emitting device according to an example. FIG. 21 is a diagram illustrating the absorption spectrum and emission spectrum of a material used in a light-emitting device according to an example. FIG. 22 is a diagram illustrating the current density-luminance characteristic of a light-emitting device according to an example. FIG. 23 is a diagram illustrating the luminance-current efficiency characteristic of a light-emitting device according to an example. FIG. 24 is a diagram illustrating the voltage-luminance characteristic of a light-emitting device according to an example. FIG. 25 is a diagram illustrating the voltage-current characteristic of a light-emitting device according to an example. FIG. 26 is a diagram illustrating the luminance-external quantum efficiency characteristic of a light-emitting device according to an example. FIG. 27 is a diagram illustrating the emission spectrum of a light-emitting device according to an example. FIG. 28 is a diagram illustrating the normalized luminance-time change characteristic of a light-emitting device according to an example.FIG. 29 is a diagram illustrating the voltage-current characteristics of the Reference Device according to the Example. FIG. 30 is a diagram illustrating the emission spectrum of the Reference Device according to the Example. FIG. 31 is a diagram illustrating changes in emission intensity when the Reference Device according to the Example is pulse-driven. FIG. 32 is a diagram illustrating the current density-luminance characteristics of the light-emitting device according to the Example. FIG. 33 is a diagram illustrating the luminance-current efficiency characteristics of the light-emitting device according to the Example. FIG. 34 is a diagram illustrating the voltage-luminance characteristics of the light-emitting device according to the Example. FIG. 35 is a diagram illustrating the voltage-current characteristics of the light-emitting device according to the Example. FIG. 36 is a diagram illustrating the luminance-external quantum efficiency characteristics of the light-emitting device according to the Example. FIG. 37 is a diagram illustrating the emission spectrum of the light-emitting device according to the Example. FIG. 38 is a diagram illustrating the normalized luminance-time change characteristics of the light-emitting device according to the Example. FIG. 39 is a diagram illustrating the current density-luminance characteristics of the light-emitting device according to the Example. FIG. 40 is a diagram illustrating the luminance-current efficiency characteristics of the light-emitting device according to the Example. FIG. 41 is a diagram illustrating the voltage-luminance characteristics of the light-emitting device according to the Example. FIG. 42 is a diagram illustrating the voltage-current characteristics of the light-emitting device according to the Example. Fig. 43 is a diagram illustrating the luminance-external quantum efficiency characteristics of a light-emitting device according to an example. Fig. 44 is a diagram illustrating the emission spectrum of a light-emitting device according to an example. Fig. 45 is a diagram illustrating the normalized luminance-time change characteristics of a light-emitting device according to an example. Fig. 46 is a diagram illustrating the normalized luminance-time change characteristics of a light-emitting device according to an example.

[0054] A light-emitting device according to one embodiment of the present invention includes a first electrode, a second electrode, and a first layer, and the second electrode has a region overlapping with the first electrode. The first layer is located between the first electrode and the second electrode, and includes a light-emitting material, a first organic compound, and a first material. The light-emitting material has a function of emitting fluorescence, and the light-emitting material has an edge at the longest wavelength of its absorption spectrum at a first wavelength. The first organic compound has a function of converting triplet excitation energy into light emission, and the light emission has an edge at the shortest wavelength of its spectrum at a second wavelength, and the second wavelength is shorter than the first wavelength. The first organic compound also includes a first substituent R１ and the first substituent R １ is any one of an alkyl group, a cycloalkyl group, and a trialkylsilyl group. The first material has a function of emitting delayed fluorescence at room temperature, and the difference between the HOMO level and the LUMO level of the first material is smaller than that of the first organic compound.

[0055] This allows the first organic compound to be used as an energy donor material, and allows energy transfer of the energy donor material, particularly energy in a triplet excited state, to the light-emitting material. １ The distance between the centers of the energy donor material and the adjacent light-emitting material can be adjusted appropriately. Energy transfer via the Dexter mechanism can be suppressed. Energy transfer via the Förster mechanism can be made dominant. The light-emitting material can be brought into a singlet excited state. The probability of generating the singlet excited state of the light-emitting material can be increased. Light-emitting efficiency can also be improved.

[0056] Furthermore, triplet excitons generated in the first material can be converted into singlet excitons. Furthermore, the difference between the HOMO level and the LUMO level of the first material can be made smaller than the difference between the HOMO level and the LUMO level of the first organic compound, thereby increasing the number of carriers moving through the first material. Furthermore, the recombination probability of carriers in the first material can be increased. Furthermore, energy can be transferred from excitons generated in the first material to an energy donor material. Furthermore, excitons can be generated in the first material, and the energy of the excitons can be transferred to the light-emitting material via the energy donor material. Furthermore, the light-emitting material can be brought into a singlet excited state. Furthermore, the probability of generating a singlet excited state in the light-emitting material can be increased. Furthermore, the light-emitting efficiency can be increased. As a result, a novel light-emitting device with excellent convenience, usefulness, and reliability can be provided.

[0057] The first layer includes a light-emitting material FM and an exciton-harvesting energy donor material ED (see FIG. 1E). The energy donor material ED can be an organometallic complex, a TADF material, or an exciplex. The energy donor material ED has a substituent R between it and the adjacent light-emitting material FM. １ or a substituent R ２ The distance between the centers of the energy donor material ED and the adjacent light-emitting material FM can be adjusted appropriately. Energy transfer by the Dexter mechanism can be suppressed. Energy transfer by the Förster mechanism (FRET) can be made dominant. Generally, the Dexter mechanism predominates when the distance between the energy donor material ED and the light-emitting material FM is 1 nm or less (see FIG. 1D), and the Förster mechanism predominates when the distance is 1 nm or more and 10 nm or less (see FIG. 1E). The light-emitting material FM can be brought into a singlet excited state. The probability of generating a singlet excited state of the light-emitting material FM can be increased. The luminous efficiency can be improved. The reliability can be increased.

[0058] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below. In the configuration of the invention described below, the same parts or parts having similar functions will be denoted by the same reference numerals in different drawings, and repeated explanations will be omitted.

[0059] Embodiment 1 In this embodiment, a structure of a light-emitting device 150 of one embodiment of the present invention will be described with reference to FIGS.

[0060] In this specification, etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. Also, in this specification, etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0061] In this specification and the like, a structure in which different light-emitting layers are formed or different light-emitting layers are painted for each color light-emitting device (here, blue (B), green (G), and red (R)) may be referred to as an SBS (Side By Side) structure. In this specification and the like, a light-emitting device that can emit white light may be referred to as a white light-emitting device. In addition, a white light-emitting device can be made into a light-emitting device that displays full color by combining it with a colored layer (for example, a color filter).

[0062] Furthermore, light-emitting devices can be broadly divided into single structures and tandem structures. A single-structure device has one light-emitting unit between a pair of electrodes, and the light-emitting unit preferably includes one or more light-emitting layers. To obtain white light emission, two or more light-emitting layers may be selected so that the light emitted from each of the two or more light-emitting layers has a complementary color relationship. For example, by making the emission color of the first light-emitting layer and the emission color of the second light-emitting layer complementary, a configuration in which the entire light-emitting device emits white light can be obtained. The same applies to light-emitting devices having three or more light-emitting layers.

[0063] A tandem-structure device preferably has two or more light-emitting units between a pair of electrodes, and each light-emitting unit preferably includes one or more light-emitting layers. To obtain white light emission, light from the light-emitting layers of the light-emitting units may be combined to obtain white light emission. The configuration for obtaining white light emission is the same as that of the single-structure device. In a tandem-structure device, it is preferable to provide an intermediate layer such as a charge-generating layer between the light-emitting units.

[0064] Furthermore, when comparing the above-described white light-emitting device (single structure or tandem structure) with a light-emitting device having an SBS structure, the light-emitting device having an SBS structure can reduce power consumption compared to the white light-emitting device. If it is desired to reduce power consumption, it is preferable to use a light-emitting device having an SBS structure. On the other hand, the manufacturing process of a white light-emitting device is simpler than that of a light-emitting device having an SBS structure, and therefore the manufacturing cost can be reduced or the manufacturing yield can be increased, making it preferable.

[0065] <Configuration Example of Light-Emitting Device 150> Light-emitting device 150 described in this embodiment has electrode 101, electrode 102, and unit 103 (see FIG. 1A ). Electrode 102 has an area overlapping with electrode 101, and unit 103 has an area sandwiched between electrode 101 and electrode 102.

[0066] <Configuration Example of Unit 103> The unit 103 has a single layer structure or a laminated structure. For example, the unit 103 includes a layer 111, a layer 112, and a layer 113. The unit 103 has a function of emitting light EL1.

[0067] Layer 111 comprises a region sandwiched between layers 112 and 113 , layer 112 comprises a region sandwiched between electrode 101 and layer 111 , and layer 113 comprises a region sandwiched between electrode 102 and layer 111 .

[0068] For example, a layer selected from functional layers such as a light-emitting layer, a hole-transporting layer, an electron-transporting layer, and a carrier-blocking layer can be used in unit 103. Also, a layer selected from functional layers such as a hole-injecting layer, an electron-injecting layer, an exciton-blocking layer, and a charge-generating layer can be used in unit 103.

[0069] <<Configuration Example 1 of Layer 111>> The layer 111 contains a light-emitting material FM, an energy donor material ED, and a host material.

[0070] [Example 1 of Light-Emitting Material FM] The light-emitting material FM has a function of emitting fluorescence, and has an absorption spectrum Abs (see FIG. 1C). The light-emitting material FM can also be called a fluorescent material.

[0071] The absorption spectrum Abs of the light-emitting material FM has an end point located at the longest wavelength at a wavelength λabs (nm). The wavelength λabs (nm) can be calculated by drawing a tangent to the absorption spectrum at the longest wavelength among the wavelengths at which the slope of the tangent is minimal, and determining the wavelength at the intersection of the tangent and the horizontal axis as λabs (nm). In other words, λabs (nm) is the absorption end point of the absorption spectrum.

[0072] [Example 2 of Light-Emitting Material FM] Furthermore, the fluorescence emitted by the light-emitting material FM has a fluorescence spectrum φf, and the fluorescence spectrum φf has its end located at the shortest wavelength at wavelength λf (nm) (see FIG. 1C ). λf (nm) can be calculated by drawing a tangent to the fluorescence spectrum at the shortest wavelength among the wavelengths at which the slope of the tangent is maximum, and determining the wavelength at the intersection of the tangent and the horizontal axis as λf (nm). In other words, λf (nm) is the onset on the short wavelength side of the fluorescence spectrum.

[0073] [Example 3 of Light-Emitting Material FM] For example, the following fluorescent light-emitting materials can be used for the layer 111. However, the present invention is not limited to these, and various known fluorescent light-emitting materials can be used for the layer 111.

[0074] Specifically, N,N,N',N'-tetrakis(4-methylphenyl)-9,10-anthracenediamine (abbreviation: TTPA), N,N-diphenylquinacridone (abbreviation: DPQd), and the like can be used.

[0075]

[0076] [Example 1 of Energy Donor Material ED] The energy donor material ED has a function of converting triplet excitation energy into luminescence, and the emission spectrum φp of the energy donor material ED has a region OLP that overlaps with the absorption spectrum Abs of the luminescent material FM (see FIG. 1C ). The region OLP is in the absorption band located at the longest wavelength of the absorption spectrum Abs of the luminescent material FM.

[0077] For example, an organometallic complex can be used as the energy donor material ED. The organometallic complex has the function of emitting phosphorescence at room temperature, and the phosphorescence spectrum of the organometallic complex overlaps with the absorption spectrum of the light-emitting material FM. That is, the emission spectrum of the energy donor material ED overlaps with the absorption spectrum Abs of the light-emitting material FM.

[0078] The phosphorescence spectrum of the organometallic complex has its shortest wavelength end at wavelength λp (nm), which is shorter than wavelength λabs (see FIG. 1C ). To calculate λp (nm), a tangent line is drawn at the shortest wavelength among the wavelengths at which the slope of the tangent line of the phosphorescence spectrum is maximized, and the wavelength at the intersection of the tangent line and the horizontal axis is taken as λp (nm). In other words, λp (nm) is the onset on the short wavelength side of the phosphorescence spectrum.

[0079] Preferably, the wavelength λp (nm) and the wavelength λabs (nm) satisfy the relationship of the following formula (2): whereby the absorption band located at the longest wavelength of the light-emitting material FM overlaps well with the phosphorescence spectrum of the organometallic complex.

[0080]

[0081] Preferably, the wavelength λp (nm) and the wavelength λf (nm) satisfy the relationship of the following formula (3): whereby the absorption band located at the longest wavelength of the light-emitting material FM overlaps well with the phosphorescence spectrum of the organometallic complex.

[0082]

[0083] For example, an organometallic complex can be used as the energy donor material ED. The organometallic complex has a ligand, and the ligand has a substituent R １ The substituent R １ is either an alkyl group, a cycloalkyl group, or a trialkylsilyl group.

[0084] In addition, the substituent R １ is an alkyl group, the number of carbon atoms in the alkyl group is 3 or more and 12 or less, and the substituent R １is a cycloalkyl group, the number of carbon atoms forming the ring of the cycloalkyl group is 3 or more and 10 or less, and the substituent R １ When is a trialkylsilyl group, the trialkylsilyl group has 3 or more and 12 or less carbon atoms.

[0085] Examples of secondary or tertiary alkyl groups having 3 to 12 carbon atoms include branched alkyl groups such as isopropyl and tert-butyl. The branched alkyl groups are not limited to these. Examples of cycloalkyl groups having 3 to 10 carbon atoms include cyclopropyl, cyclobutyl, cyclohexyl, norbornyl, and adamantyl. The cycloalkyl groups are not limited to these. Furthermore, when the cycloalkyl group has a substituent, the substituent may be an alkyl group having 1 to 7 carbon atoms such as methyl, isopropyl, or tert-butyl; a cycloalkyl group having 5 to 7 carbon atoms such as cyclopentyl, cyclohexyl, cycloheptyl, or 8,9,10-trinorbornanyl; or an aryl group having 6 to 12 carbon atoms such as phenyl, naphthyl, or biphenyl. Examples of trialkylsilyl groups having 3 to 12 carbon atoms include trimethylsilyl, triethylsilyl, and tert-butyldimethylsilyl. The trialkylsilyl group is not limited to these.

[0086] For example, the substituent R １ The light-emitting device can have deuterium instead of hydrogen, which can suppress the release of hydrogen and improve the reliability of the light-emitting device.

[0087] The organometallic complex has a first HOMO level HOMO1 and a first LUMO level LUMO1 (see FIG. 1B).

[0088] [Example 2 of Energy Donor Material ED] An organometallic complex can be used as the energy donor material ED. The organometallic complex has a ligand and a transition metal. For example, a transition metal can be used as the central metal. In particular, organometallic complexes having iridium or platinum as the central metal are preferred. This makes it possible to obtain a radioactive triplet excited state. Alternatively, the organometallic complex can be made chemically stable. Note that trivalent iridium is particularly preferred as the central metal, from the viewpoint that the ligands around the central metal tend to form a sterically bulky structure, thereby making it easier to suppress Dexter migration.

[0089] The ligand comprises a first ring and a second ring and at least one substituent R １ is attached to at least one of the first ring or the second ring.

[0090] The first ring is a six-membered ring and contains an atom covalently bonded to the transition metal as a constituent atom. The second ring is a five- or six-membered ring and contains an atom coordinating to the transition metal as a constituent atom. The first ring is preferably a benzene ring. The constituent atom coordinating to the transition metal may be N, as in a pyridine ring, or C, as in a carbene.

[0091] [Example 3 of Energy Donor Material ED] For example, an organometallic complex can be used as the energy donor material ED. The organometallic complex has a ligand.

[0092] The ligand has a phenylpyridine skeleton and at least one substituent R １ is bonded to a carbon atom of the phenylpyridine skeleton.

[0093] [Example 4 of Energy Donor Material ED] For example, an organometallic complex represented by the following general formula (G0) can be used as the energy donor material ED.

[0094]

[0095] In the above general formula, L is a ligand, and n is an integer of 1 to 3. Preferably, n is an integer of 2 or more. This makes it possible to suppress energy transfer via the Dexter mechanism, or to make energy transfer via the Förster mechanism predominant.

[0096] Also, R １０１ ~R １０８ is hydrogen or a substituent, and R １０１ ~R １０８ contains one or more of an alkyl group, a substituted or unsubstituted cycloalkyl group, or a trialkylsilyl group. The alkyl group is preferably an alkyl group having 3 to 12 carbon atoms, the cycloalkyl group is preferably an alkyl group having 3 to 10 carbon atoms, and the trialkylsilyl group is preferably an alkyl group having 3 to 12 carbon atoms. In other words, the above-mentioned substituent R １ is R １０１ ~R １０８ Included in.

[0097] This makes it possible to improve the luminous efficiency, thereby providing a novel light-emitting device that is highly convenient, useful, and reliable.

[0098] [Example 5 of Energy Donor Material ED] For example, two ligands have a phenylpyridine skeleton and a substituent, and the substituent is bonded to a carbon of the phenylpyridine skeleton. Note that, for example, a secondary or tertiary alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms can be used as the substituent.

[0099] Specific examples of organic compounds having the above structure are shown below.

[0100]

[0101] [Example 6 of Energy Donor Material ED] For example, three ligands have a phenylpyridine skeleton and one or more substituents, and the substituents are bonded to carbon atoms of the phenylpyridine skeleton. For example, a secondary or tertiary alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms can be used as the substituent. Furthermore, ligands with the same structure can be used for two of the three ligands.

[0102] Specific examples of organic compounds having the above structure are shown below.

[0103]

[0104] [Example 7 of Energy Donor Material ED] For example, three ligands have a phenylpyridine skeleton and a substituent, and the substituent is bonded to a carbon of the phenylpyridine skeleton. Note that, for example, a secondary or tertiary alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms can be used as the substituent. Furthermore, ligands with the same structure can be used for the three ligands.

[0105] Specific examples of organic compounds having the above structure are shown below.

[0106]

[0107] [Example 8 of Energy Donor Material ED] For example, the ligand has a phenylpyridine skeleton and a substituent, and the substituent is bonded to a carbon of the phenylpyridine skeleton. For example, a secondary or tertiary alkyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms can be used as the substituent, and a substituent in which some or all of the hydrogen atoms in the substituent are substituted with deuterium can be used. This can improve reliability.

[0108] Specific examples of organic compounds having the above structure are shown below.

[0109]

[0110] [Example 9 of Energy Donor Material ED] An organic compound capable of emitting delayed fluorescence at room temperature can be used as the energy donor material ED. For example, a substance exhibiting thermally activated delayed fluorescence can be used as the energy donor material ED. The TADF material has the ability to emit delayed fluorescence at room temperature, and its emission spectrum overlaps with the absorption spectrum of the light-emitting material FM.

[0111] The emission spectrum of the TADF material has its shortest wavelength end at wavelength λp (nm), which is shorter than wavelength λabs (see Figure 1C). To calculate λp (nm), a tangent line is drawn at the shortest wavelength among the wavelengths at which the slope of the tangent line of the emission spectrum is maximum, and the wavelength at the intersection of the tangent line and the horizontal axis is taken as λp (nm). In other words, λp (nm) is the onset on the short wavelength side of the emission spectrum.

[0112] Preferably, the wavelength λp (nm) and the wavelength λabs (nm) satisfy the relationship of the following formula (2): whereby the absorption band located at the longest wavelength of the light-emitting material FM overlaps well with the emission spectrum of the TADF material.

[0113]

[0114] Preferably, the wavelength λp (nm) and the wavelength λf (nm) satisfy the relationship of the following formula (3): whereby the absorption band located at the longest wavelength of the light-emitting material FM overlaps well with the emission spectrum of the TADF material.

[0115]

[0116] For example, a TADF material can be used as the energy donor material ED. The TADF material has a substituent R １ The substituent R １ is either an alkyl group, a cycloalkyl group, or a trialkylsilyl group.

[0117] In addition, the substituent R １ is an alkyl group, the number of carbon atoms in the alkyl group is 3 or more and 12 or less, and the substituent R １is a cycloalkyl group, the number of carbon atoms forming the ring of the cycloalkyl group is 3 or more and 10 or less, and the substituent R １ When is a trialkylsilyl group, the trialkylsilyl group has 3 or more and 12 or less carbon atoms.

[0118] For example, the substituent R １ The light-emitting device can have deuterium instead of hydrogen, which can suppress the release of hydrogen and improve the reliability of the light-emitting device.

[0119] The TADF material has a first HOMO level HOMO1 and a first LUMO level LUMO1 (see FIG. 1B).

[0120] [Example 1 of Host Material] The host material has the function of emitting delayed fluorescence at room temperature. The first material can be used as the host material. The host material is contained in the light-emitting layer at a weight ratio greater than that of the light-emitting material, and more preferably, is a material that is contained in the light-emitting layer at a weight ratio greater than that of the light-emitting material. For example, a substance that exhibits thermally activated delayed fluorescence can be used as the host material. Specifically, the TADF materials exemplified below can be used as the host material. However, the host material is not limited thereto, and various known TADF materials can be used as the host material.

[0121] For example, TADF materials can include fullerene and its derivatives, acridine and its derivatives, eosin derivatives, etc. Also, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), etc. can be used as TADF materials.

[0122] Specifically, protoporphyrin-tin fluoride complex (SnF), whose structural formula is shown below, ２ (Proto IX)), mesoporphyrin-tin fluoride complex (SnF ２ (Meso IX)), hematoporphyrin-tin fluoride complex (SnF ２ (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ２(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ２ (OEP)), etioporphyrin-tin fluoride complex (SnF ２ (Etio I)), octaethylporphyrin-platinum chloride complex (PtCl ２ OEP), etc. can be used.

[0123]

[0124] Furthermore, for example, a heterocyclic compound having one or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring can be used as the TADF material.

[0125] Specifically, the structural formulas of these compounds are as follows: 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), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4 ,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10′H-spiro[acridin-9,9′-anthracene]-10′-one (abbreviation: ACRSA), and the like can be used.

[0126]

[0127] The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. In particular, among skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeletons, diazine skeletons (pyrimidine skeletons, pyrazine skeletons, pyridazine skeletons), and triazine skeletons are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeletons, benzothienopyrimidine skeletons, benzofuropyrazine skeletons, and benzothienopyrazine skeletons are preferred because they have high acceptor properties and good reliability.

[0128] Among skeletons having a π-electron-rich heteroaromatic ring, it is preferable to have at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton because they are stable and reliable. Note that the dibenzofuran skeleton is preferable as the furan skeleton, and the dibenzothiophene skeleton is preferable as the thiophene skeleton. In particular, the indole skeleton, the carbazole skeleton, the indolocarbazole skeleton, the bicarbazole skeleton, and the 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are preferable as the pyrrole skeleton.

[0129] In addition, a substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is particularly preferred because the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-deficient heteroaromatic ring are both strong, and the energy difference between the S1 level and the T1 level is small, thereby enabling efficient thermally activated delayed fluorescence to be obtained. In addition, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used instead of the π-electron-deficient heteroaromatic ring. In addition, an aromatic amine skeleton, a phenazine skeleton, or the like may be used as the π-electron-rich skeleton.

[0130] Furthermore, examples of the π-electron-deficient skeleton that can be used include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring or heteroaromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, and a sulfone skeleton.

[0131] In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0132] [Example 2 of Host Material] A mixture of multiple substances can be used as the host material. In other words, a mixture of multiple substances can be used as the first material. For example, a mixture of substances A and B, in which substances A and B form an exciplex, can be used as the host material. Preferably, a mixture of a material having hole-transporting properties and a material having electron-transporting properties can be used as the host material. Note that the weight ratio of the material having hole-transporting properties to the material having electron-transporting properties contained in the mixture may be (material having hole-transporting properties / material having electron-transporting properties) = (1 / 19) or more and (19 / 1) or less. This allows easy adjustment of the carrier transport property of the layer 111. Furthermore, the recombination region can be easily controlled.

[0133] The HOMO level of the material having hole transport properties is preferably equal to or higher than the HOMO level of the material having electron transport properties. Alternatively, the LUMO level of the material having hole transport properties is preferably equal to or higher than the LUMO level of the material having electron transport properties. This allows for efficient formation of an exciplex. The LUMO level and HOMO level of the material can be derived from electrochemical properties (reduction potential and oxidation potential). Specifically, the reduction potential and oxidation potential can be measured using cyclic voltammetry (CV) measurement.

[0134] The formation of exciplexes can be confirmed, for example, by comparing the emission spectra of a material having hole transport properties, a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing the phenomenon in which the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak on the longer wavelength side). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a material having hole transport properties, the transient PL of a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lifetime component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL may also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of a material having hole transport properties, the transient EL of a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing the differences in transient response.

[0135] [Host Material Example 3] The first material used as the host material has a second HOMO level HOMO2 and a second LUMO level LUMO2. When a mixed material of a plurality of substances is used as the host material, the HOMO levels of the plurality of materials can be compared, and the highest HOMO level can be set as the second HOMO level HOMO2. Furthermore, the LUMO levels of the plurality of materials can be compared, and the lowest LUMO level can be set as the second LUMO level LUMO2.

[0136] The first HOMO level HOMO1, the first LUMO level LUMO1, the second HOMO level HOMO2, and the second LUMO level LUMO2 satisfy the following formula (1).

[0137]

[0138] As a result, by using an organometallic complex or a TADF material as the energy donor material ED, the energy of the energy donor material ED, particularly the energy of the triplet excited state, can be transferred to the light-emitting material FM. １sandwiched therebetween. In addition, the center-to-center distance between the energy donor material ED and the adjacent light-emitting material FM can be made appropriate. In addition, energy transfer by the Dexter mechanism can be suppressed. In addition, energy transfer by the Förster mechanism can be made dominant. In addition, the light-emitting material FM can be brought into a singlet excited state. In addition, the probability of generating the singlet excited state of the light-emitting material FM can be increased. In addition, the light-emitting efficiency can be increased.

[0139] Furthermore, triplet excitons generated in the host material can be converted into singlet excitons. Furthermore, the difference between the HOMO level and LUMO level of the host material can be made smaller than the difference between the HOMO level and LUMO level of the energy donor material ED, thereby increasing the number of carriers moving through the host material. Furthermore, the recombination probability of carriers in the host material can be increased. Furthermore, energy can be transferred from excitons generated in the host material to the energy donor material ED. Furthermore, excitons can be generated in the host material, and the energy of the excitons can be transferred to the light-emitting material FM via the energy donor material ED. Furthermore, the light-emitting material FM can be brought into a singlet excited state. Furthermore, the probability of generating a singlet excited state of the light-emitting material FM can be increased. Furthermore, the light-emitting efficiency can be improved. As a result, a novel light-emitting device with excellent convenience, usefulness, and reliability can be provided.

[0140] Host Material Example 4 The second HOMO level HOMO2 of the host material is higher than the first HOMO level HOMO1 of the energy donor material ED (see FIG. 1B ), and the second LUMO level LUMO2 of the host material is lower than the first LUMO level LUMO1 of the energy donor material ED.

[0141] This can increase the number of carriers moving through the host material. It can also increase the recombination probability of carriers in the host material. It can also transfer energy from excitons generated in the host material to the energy donor material ED. It can also generate excitons in the host material, and transfer the energy of the excitons to the light-emitting material FM via the energy donor material ED. It can also place the light-emitting material FM in a singlet excited state. It can also increase the probability of generating a singlet excited state in the light-emitting material FM. It can also increase the light-emitting efficiency. As a result, it is possible to provide a novel light-emitting device that is highly convenient, useful, and reliable.

[0142] [Example 4 of Light-Emitting Material FM] A preferred light-emitting material FM that can be used in the light-emitting device according to one embodiment of the present invention is a light-emitting material having a substituent R ２ At least one of the following is provided.

[0143] Substituent R ２ is selected from a methyl group, a branched alkyl group, a substituted or unsubstituted cycloalkyl group, and a trialkylsilyl group. ２ is a branched alkyl group, the branched alkyl group has 3 to 12 carbon atoms, and the substituent R ２ is a cycloalkyl group, the number of carbon atoms forming the ring of the cycloalkyl group is 3 or more and 10 or less, and the substituent R ２ When is a trialkylsilyl group, the trialkylsilyl group has 3 or more and 12 or less carbon atoms.

[0144] Examples of secondary or tertiary alkyl groups having 3 to 12 carbon atoms include branched alkyl groups such as isopropyl and tert-butyl. The branched alkyl groups are not limited to these. Examples of cycloalkyl groups having 3 to 10 carbon atoms include cyclopropyl, cyclobutyl, cyclohexyl, norbornyl, and adamantyl. The cycloalkyl groups are not limited to these. Furthermore, when the cycloalkyl group has a substituent, the substituent may be an alkyl group having 1 to 7 carbon atoms such as methyl, isopropyl, or tert-butyl; a cycloalkyl group having 5 to 7 carbon atoms such as cyclopentyl, cyclohexyl, cycloheptyl, or 8,9,10-trinorbornanyl; or an aryl group having 6 to 12 carbon atoms such as phenyl, naphthyl, or biphenyl. Examples of trialkylsilyl groups having 3 to 12 carbon atoms include trimethylsilyl, triethylsilyl, and tert-butyldimethylsilyl. The trialkylsilyl group is not limited to these.

[0145] Substituent R ２ When R is a branched alkyl group, for example, a secondary alkyl group or a tertiary alkyl group may be substituted with a substituent R ２ Specifically, an alkyl group having a branched carbon atom bonded to the main skeleton can be used as a substituent R ２ This can reduce the number of α-hydrogens and improve the reliability of the light-emitting device.

[0146] Substituent R ２ When R is a branched alkyl group, for example, an alkyl group having 3 or more and 4 or less carbon atoms may be used as the substituent R ２ It can be used for.

[0147] Substituent R ２ is a cycloalkyl group, for example, a cycloalkyl group having 3 or more and 6 or less carbon atoms can be used as the substituent R ２ It can be used for.

[0148] Substituent R ２is a trialkylsilyl group, for example, a trimethylsilyl group can be substituted with the substituent R ２ It can be used for.

[0149] As a result, the light-emitting material FM has a substituent R ２ sandwiched therebetween. In addition, the center-to-center distance between the energy donor material ED and the adjacent light-emitting material FM can be made appropriate. In addition, energy transfer by the Dexter mechanism can be suppressed. In addition, energy transfer by the Förster mechanism can be made dominant. In addition, the light-emitting material FM can be brought into a singlet excited state. In addition, the probability of generating the singlet excited state of the light-emitting material FM can be increased. In addition, the light-emitting efficiency can be increased. As a result, a novel light-emitting device excellent in convenience, usefulness, and reliability can be provided.

[0150] For example, the substituent R ２ The light-emitting device can have deuterium instead of hydrogen, which can suppress the release of hydrogen and improve the reliability of the light-emitting device.

[0151] [Example 5 of Light-Emitting Material FM] The light-emitting material FM that can be used in the light-emitting device of one embodiment of the present invention is a light-emitting material having a fused aromatic ring or a fused heteroaromatic ring and five or more substituents R ２ And, it is equipped with.

[0152] The condensed aromatic ring or the condensed heteroaromatic ring has 3 to 10 rings. ２ each independently includes a branched alkyl group, a substituted or unsubstituted cycloalkyl group, or a trialkylsilyl group. ２ is other than a methyl group. ２ is a branched alkyl group, the branched alkyl group has 3 to 12 carbon atoms, and the substituent R ２ is a cycloalkyl group, the number of carbon atoms forming the ring of the cycloalkyl group is 3 or more and 10 or less, and the substituent R ２ When is a trialkylsilyl group, the trialkylsilyl group has 3 or more and 12 or less carbon atoms.

[0153] [Example 6 of Light-Emitting Material FM] The light-emitting material FM that can be used in the light-emitting device of one embodiment of the present invention is a light-emitting material having a fused aromatic ring or a fused heteroaromatic ring and three or more substituents R ２ And, it is equipped with.

[0154] The condensed aromatic ring or the condensed heteroaromatic ring has 3 to 10 rings. ２ does not directly bond to the fused aromatic ring or the fused heteroaromatic ring. ２ Each of the substituents R ２ is an alkyl group, the number of carbon atoms in the alkyl group is 3 or more and 12 or less, and the substituent R ２ is a cycloalkyl group, the number of carbon atoms forming the ring of the cycloalkyl group is 3 or more and 10 or less, and the substituent R ２ When is a trialkylsilyl group, the trialkylsilyl group has 3 or more and 12 or less carbon atoms.

[0155] [Example 7 of Light-Emitting Material FM] The light-emitting material FM that can be used in the light-emitting device of one embodiment of the present invention includes a fused aromatic ring or a fused heteroaromatic ring and a diarylamino group.

[0156] The fused aromatic ring or the fused heteroaromatic ring has 3 to 10 rings. The nitrogen atom of the diarylamino group is bonded to the fused aromatic ring or the fused heteroaromatic ring, and the aryl group of the diarylamino group is bonded to the substituent R ２ and combine.

[0157] [Example 8 of Light-Emitting Material FM] For example, an organic compound represented by the following general formula (G1) can be used as the light-emitting material FM.

[0158]

[0159] In the above general formula, A is a π-conjugated system, and for example, a fused aromatic ring or a fused heteroaromatic ring can be used for A. Specifically, a fused aromatic ring having 3 to 10 rings or a fused heteroaromatic ring having 3 to 10 rings can be used for A.

[0160] Also, R ２１１ ~R ２４２ is hydrogen or a substituent, and R ２１１ ~R ２４２ contains one or more of a branched alkyl group, a substituted or unsubstituted cycloalkyl group, or a trialkylsilyl group. The branched alkyl group is preferably a secondary or tertiary alkyl group having 3 to 12 carbon atoms, the cycloalkyl group is preferably a group having 3 to 10 carbon atoms, and the trialkylsilyl group is preferably a group having 3 to 12 carbon atoms. In other words, the above-mentioned substituent R ２ is R ２１１ ~R ２４２ Included in.

[0161] N is a nitrogen atom, and Ar １ ~Ar ４ is an aryl group. In other words, the light-emitting material FM comprises a diarylamino group. The nitrogen atom of the diarylamino group is bonded to A, and the aryl group of the diarylamino group is bonded to a substituent R ２ It is preferable that the light-emitting material FM has two or more diarylamino groups.

[0162] [Example 9 of Light-Emitting Material FM] For example, an organic compound represented by the following general formula (G2) or (G3) can be used as the light-emitting material FM.

[0163]

[0164]

[0165] In the above general formula, R ２１１ ~R ２５８ is hydrogen or a substituent, and R ２１１ ~R ２５８ contains one or more of a branched alkyl group, a substituted or unsubstituted cycloalkyl group, or a trialkylsilyl group. The branched alkyl group is preferably a secondary or tertiary alkyl group having 3 to 12 carbon atoms, the cycloalkyl group is preferably a group having 3 to 10 carbon atoms, and the trialkylsilyl group is preferably a group having 3 to 12 carbon atoms. In other words, the above-mentioned substituent R ２ is R ２１１ ~R２５８ Included in.

[0166] [Example 10 of Light-Emitting Material FM] For example, an organic compound represented by the following general formula (G4) or (G5) can be used as the light-emitting material FM.

[0167]

[0168]

[0169] In the above general formula, R ２１１ ~R ２５８ is hydrogen or a substituent, and R ２１１ ~R ２５８ contains one or more of a branched alkyl group, a substituted or unsubstituted cycloalkyl group, or a trialkylsilyl group. The branched alkyl group is preferably a secondary or tertiary alkyl group having 3 to 12 carbon atoms, the cycloalkyl group is preferably a group having 3 to 10 carbon atoms, and the trialkylsilyl group is preferably a group having 3 to 12 carbon atoms. In other words, the above-mentioned substituent R ２ is R ２１１ ~R ２５８ In the diarylamino group, the substituent R ２ is attached to the carbon atom meta to the carbon atom of the benzene ring that is attached to the nitrogen.

[0170] This allows the organometallic complex to be used as the energy donor material ED, and allows the energy of the energy donor material ED, particularly the energy of the triplet excited state, to be transferred to the light-emitting material FM. Alternatively, the energy donor material ED may have a first substituent R １ and a second substituent R ２ or sandwiching the light-emitting material FM between the light-emitting elements. Alternatively, energy transfer by the Dexter mechanism can be suppressed. Alternatively, energy transfer by the Förster mechanism can be made dominant. Alternatively, the light-emitting material FM can be brought into a singlet excited state. Alternatively, the probability of generating the singlet excited state of the light-emitting material FM can be increased. Alternatively, the light-emitting efficiency can be increased. Alternatively, the concentration of the light-emitting material FM can be increased. As a result, a novel light-emitting device excellent in convenience, usefulness, and reliability can be provided.

[0171] Specific examples of organic compounds having the above structure are shown below.

[0172]

[0173]

[0174]

[0175]

[0176] [Example 10 of Light-Emitting Material FM] The light-emitting material FM has a third LUMO level LUMO3 (see FIG. 1B), which is higher than the second LUMO level LUMO2 of the host material.

[0177] This can suppress electron capture by the light-emitting material FM. It can also suppress the probability of carrier recombination in the light-emitting material FM. It can also suppress the phenomenon of the light-emitting material FM being in a triplet excited state due to carrier recombination in the light-emitting material FM. It can also generate excitons in the host material, and transfer the energy of the excitons to the light-emitting material FM via the energy donor material ED. It can also increase the probability of generating a singlet excited state in the light-emitting material FM. It can also increase the luminous efficiency. As a result, it is possible to provide a novel light-emitting device that is highly convenient, useful, and reliable.

[0178] <<Structural Example 2 of Layer 111>> The layer 111 includes a light-emitting material FM, an energy donor material ED, and a host material. Note that this example differs from the first example of the layer 111 in that the layer 111 includes a carrier capture level.

[0179] Example 2 of Energy Donor Material ED The first HOMO level HOMO1 of the energy donor material ED is higher than the second HOMO level HOMO2 of the host material (see FIG. 2A).

[0180] This allows the energy donor material ED to easily capture holes. Also, the recombination probability of carriers in the energy donor material ED can be increased. Furthermore, by using an organometallic complex or a TADF material as the energy donor material ED, the energy of the energy donor material ED, particularly the energy of the triplet excited state, can be transferred to the light-emitting material FM. Furthermore, the energy donor material ED has a substituent R between it and the adjacent light-emitting material FM. １ sandwiched therebetween. In addition, the center-to-center distance between the energy donor material ED and the adjacent light-emitting material FM can be made appropriate. In addition, energy transfer by the Dexter mechanism can be suppressed. In addition, energy transfer by the Förster mechanism can be made dominant. In addition, the light-emitting material FM can be brought into a singlet excited state. In addition, the probability of generating the singlet excited state of the light-emitting material FM can be increased. In addition, the light-emitting efficiency can be increased. As a result, a novel light-emitting device excellent in convenience, usefulness, and reliability can be provided.

[0181] Example 3 of Energy Donor Material ED The first LUMO level LUMO1 of the energy donor material ED is lower than the second LUMO level LUMO2 of the host material (see FIG. 2B).

[0182] This allows the energy donor material ED to easily capture electrons. Also, the recombination probability of carriers in the energy donor material ED can be increased. Furthermore, by using an organometallic complex or a TADF material as the energy donor material ED, the energy of the energy donor material ED, particularly the energy of the triplet excited state, can be transferred to the light-emitting material FM. Furthermore, the energy donor material ED has a substituent R between it and the adjacent light-emitting material FM. １sandwiched therebetween. In addition, the center-to-center distance between the energy donor material ED and the adjacent light-emitting material FM can be made appropriate. In addition, energy transfer by the Dexter mechanism can be suppressed. In addition, energy transfer by the Förster mechanism can be made dominant. In addition, the light-emitting material FM can be brought into a singlet excited state. In addition, the probability of generating the singlet excited state of the light-emitting material FM can be increased. In addition, the light-emitting efficiency can be increased. As a result, a novel light-emitting device excellent in convenience, usefulness, and reliability can be provided.

[0183] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0184] Embodiment 2 In this embodiment, a structure of a light-emitting device 150 of one embodiment of the present invention will be described with reference to FIGS.

[0185] <Configuration Example of Light-Emitting Device 150> Light-emitting device 150 described in this embodiment has electrode 101, electrode 102, and unit 103. Electrode 102 has a region overlapping with electrode 101, and unit 103 has a region sandwiched between electrode 101 and electrode 102.

[0186] <Configuration Example of Unit 103> The unit 103 has a single layer structure or a laminated structure. For example, the unit 103 includes a layer 111, a layer 112, and a layer 113 (see FIG. 1A). The unit 103 has a function of emitting light EL1.

[0187] For example, the unit 103 may be a layer selected from functional layers such as a light-emitting layer, a hole transport layer, an electron transport layer, and a carrier block layer.

[0188] The layer 111 includes a region sandwiched between the layer 112 and the layer 113, the layer 112 includes a region sandwiched between the electrode 101 and the layer 111, and the layer 113 includes a region sandwiched between the electrode 102 and the layer 111. Note that the structure described in Embodiment 1 can be used for the layer 111, for example.

[0189] <<Structure Example of Layer 112>> For example, a material having a hole-transporting property can be used for the layer 112. The layer 112 can also be referred to as a hole-transport layer. Note that a structure in which a material having a larger band gap than that of the light-emitting material contained in the layer 111 is used for the layer 112 is preferable. This can suppress energy transfer from excitons generated in the layer 111 to the layer 112.

[0190] [Material having hole transport properties] A material having a hole mobility of 1×10 −６ cm ２ A material having a hole transporting property can be suitably used as a material having a hole transporting property.

[0191] For example, an amine compound or an organic compound having a π-electron-rich heteroaromatic ring skeleton can be used as a material having hole transport properties. Specifically, a compound having an aromatic amine skeleton, a compound having a carbazole skeleton, a compound having a thiophene skeleton, a compound having a furan skeleton, or the like can be used. In particular, a compound having an aromatic amine skeleton or a compound having a carbazole skeleton is preferable because it has good reliability, high hole transport properties, and contributes to reducing driving voltage.

[0192] Examples of compounds having an aromatic amine skeleton include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), and 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP). , 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBiBP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), and the like can be used.

[0193] Examples of compounds having a carbazole skeleton that can be used include 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), and 3,3′-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP).

[0194] Examples of compounds having a thiophene skeleton that can be used include 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).

[0195] Examples of compounds having a furan skeleton that can be used include 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), and the like.

[0196] <<Structure Example of Layer 113>> For example, a material having an electron-transporting property, a material having an anthracene skeleton, a mixed material, or the like can be used for the layer 113. The layer 113 can also be referred to as an electron-transporting layer. Note that a structure in which a material having a larger band gap than that of the light-emitting material contained in the layer 111 is used for the layer 113 is preferable. This can suppress energy transfer from excitons generated in the layer 111 to the layer 113.

[0197] [Electron-Transporting Material] For example, a metal complex or an organic compound having a π-electron-deficient heteroaromatic ring skeleton can be used as the electron-transporting material.

[0198] When the square root of the electric field strength [V / cm] is 600, the electron mobility is 1×10 −７ cm ２ / Vs or more, 5×10 −５ cm ２ A material having a .DELTA. / Vs or less can be suitably used as a material having electron transport properties. This can suppress the electron transport properties in the electron transport layer. Alternatively, it can control the amount of electrons injected into the light-emitting layer. Alternatively, it can prevent the light-emitting layer from becoming electron-excessive.

[0199] Examples of metal complexes include bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq ２ ), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), and the like can be used.

[0200] Examples of organic compounds having a π-electron-deficient heteroaromatic ring skeleton include heterocyclic compounds having a polyazole skeleton, heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a pyridine skeleton, and heterocyclic compounds having a triazine skeleton. In particular, heterocyclic compounds having a diazine skeleton or heterocyclic compounds having a pyridine skeleton are preferred because of their high reliability. Furthermore, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton have high electron transport properties and can reduce driving voltage.

[0201] Examples of heterocyclic compounds having a polyazole skeleton include 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: O XD-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 the like can be used.

[0202] Examples of heterocyclic compounds having a diazine skeleton include 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: 2mDBTBPDBq-II), and 2-[3′-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II). ]quinoxaline (abbreviation: 2mCzBPDBq), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzo[h]quinazoline (abbreviation: 4,8mDBtP2Bqn), etc. can be used.

[0203] Examples of heterocyclic compounds having a pyridine skeleton include 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), and the like.

[0204] Examples of heterocyclic compounds having a triazine skeleton include 2-[3′-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 2-[(1,1′-biphenyl)-4-yl]-4-phenyl-6-[9,9′-spirobi(9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFT zn), 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), and the like can be used.

[0205] [Material Having an Anthracene Skeleton] An organic compound having an anthracene skeleton can be used for the layer 113. In particular, an organic compound having both an anthracene skeleton and a heterocyclic skeleton can be preferably used.

[0206] For example, an organic compound containing both an anthracene skeleton and a nitrogen-containing five-membered ring skeleton can be used. Alternatively, an organic compound containing both an anthracene skeleton and a nitrogen-containing five-membered ring skeleton containing two heteroatoms in the ring can be used. Specifically, a pyrazole ring, an imidazole ring, an oxazole ring, a thiazole ring, or the like can be suitably used as the heterocyclic skeleton.

[0207] For example, an organic compound containing both an anthracene skeleton and a nitrogen-containing six-membered ring skeleton can be used. Alternatively, an organic compound containing both an anthracene skeleton and a nitrogen-containing six-membered ring skeleton containing two heteroatoms in the ring can be used. Specifically, a pyrazine ring, a pyrimidine ring, a pyridazine ring, or the like can be suitably used as the heterocyclic skeleton.

[0208] [Configuration Example of Mixed Material] A material in which a plurality of substances are mixed can be used for the layer 113. Specifically, a mixed material containing an alkali metal, an alkali metal compound, or an alkali metal complex, and a substance having an electron-transport property can be used for the layer 113. Note that the HOMO level of the material having an electron-transport property is more preferably −6.0 eV or higher.

[0209] Furthermore, when a composite material is used for the layer 104, the composite material can be preferably used for the layer 113. For example, a composite material of a substance having an acceptor property and a material having a hole-transporting property can be used for the layer 104. Specifically, a composite material of a substance having an acceptor property and a substance having a relatively deep HOMO level HM1 of −5.7 eV or more and −5.4 eV or less can be used for the layer 104 (see FIG. 2C ). In particular, when the composite material is used for the layer 104, the composite material can be preferably used for the layer 113. This can improve the reliability of the light-emitting device.

[0210] Furthermore, a structure in which the mixed material is used for the layer 113 and the composite material is used for the layer 104, and a structure in which a material having hole-transporting properties is used for the layer 112 can be suitably used in combination. For example, a substance having a HOMO level HM2 in the range of -0.2 eV to 0 eV, relative to the relatively deep HOMO level HM1, can be used for the layer 112 (see FIG. 2C ). This can improve the reliability of the light-emitting device. Note that in this specification and the like, the above-described light-emitting device may be referred to as a Recombination-Site Tailoring Injection structure (ReSTI structure).

[0211] The alkali metal, alkali metal compound, or alkali metal complex is preferably present with a concentration difference (including zero) in the thickness direction of the layer 113 .

[0212] For example, a metal complex containing an 8-hydroxyquinolinato structure can be used. Also, a methyl-substituted metal complex containing an 8-hydroxyquinolinato structure (for example, a 2-methyl-substituted or 5-methyl-substituted metal complex) can be used.

[0213] Examples of metal complexes containing an 8-hydroxyquinolinato structure include 8-hydroxyquinolinato-lithium (abbreviation: Liq), 8-hydroxyquinolinato-sodium (abbreviation: Naq), etc. In particular, complexes of monovalent metal ions, especially lithium complexes, are preferred, with Liq being more preferred.

[0214] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0215] Embodiment 3 In this embodiment, a structure of a light-emitting device 150 of one embodiment of the present invention will be described with reference to FIG. 1A.

[0216] <Configuration Example of Light-Emitting Device 150> The light-emitting device 150 described in this embodiment includes an electrode 101, an electrode 102, a unit 103, and a layer 104. The electrode 102 has a region overlapping with the electrode 101, and the unit 103 has a region sandwiched between the electrode 101 and the electrode 102. The layer 104 has a region sandwiched between the electrode 101 and the unit 103. Note that the structure described in Embodiment 2 can be used for the unit 103, for example.

[0217] <Structure Example of Electrode 101> For example, a conductive material can be used for the electrode 101. Specifically, a metal, an alloy, a conductive compound, a mixture thereof, or the like can be used for the electrode 101. For example, a material having a work function of 4.0 eV or more can be suitably used.

[0218] For example, indium oxide-tin oxide (ITO), indium oxide-tin oxide containing silicon or silicon oxide (ITSO), indium oxide-zinc oxide, indium oxide containing tungsten oxide and zinc oxide (IWZO), etc. can be used.

[0219] Alternatively, for example, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or a nitride of a metal material (e.g., titanium nitride) can be used. Alternatively, graphene can be used.

[0220] <Structure Example of Layer 104> For example, a material having a hole-injecting property can be used for the layer 104. The layer 104 can also be referred to as a hole-injecting layer.

[0221] Specifically, a substance having an acceptor property can be used for the layer 104. Alternatively, a composite material of a substance having an acceptor property and a material having a hole-transporting property can be used for the layer 104. This can make it easier to inject holes from the electrode 101, for example. Alternatively, the driving voltage of the light-emitting device can be reduced.

[0222] [Substance Having Acceptor Property] Organic compounds and inorganic compounds can be used as the substance having acceptor property. The substance having acceptor property can extract electrons from the adjacent hole transport layer or the material having hole transport property by applying an electric field.

[0223] For example, a compound having an electron-withdrawing group (a halogen group or a cyano group) can be used as a substance having acceptor properties. Note that organic compounds having acceptor properties are easy to vapor-deposit and form into films. This can improve the productivity of light-emitting devices.

[0224] Specifically, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F ４ -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-TCCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile, and the like can be used.

[0225] In particular, a compound in which an electron-withdrawing group is bonded to a condensed aromatic ring having a plurality of heteroatoms, such as HAT-CN, is thermally stable and is therefore preferred.

[0226] [3] Radialene derivatives having an electron-withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) are also preferred because they have very high electron-accepting properties.

[0227] Specifically, α,α',α''-1,2,3-cyclopropane triylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile], and the like can be used.

[0228] Furthermore, molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, or the like can be used as the substance having acceptor properties.

[0229] In addition, phthalocyanine (abbreviation: H ２ and compounds having an aromatic amine skeleton such as 4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) and N,N′-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (abbreviation: DNTPD).

[0230] Furthermore, polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS) can also be used.

[0231] [Configuration Example 1 of Composite Material] A composite material of multiple substances can be used as a material having a hole-injecting property. For example, a composite material can be made of a substance having an acceptor property and a material having a hole-transporting property. This allows not only a material having a high work function but also a material having a low work function to be used for the electrode 101. Alternatively, a material for the electrode 101 can be selected from a wide range of materials regardless of the work function.

[0232] For example, compounds having an aromatic amine skeleton, carbazole derivatives, aromatic hydrocarbons, aromatic hydrocarbons having a vinyl group, and polymeric compounds (oligomers, dendrimers, polymers, etc.) can be used as the material having hole transport properties for the composite material. −６ cm ２ A material having a hole transporting property can be suitably used as the material of the composite material.

[0233] Furthermore, a substance having a relatively deep HOMO level can be preferably used as the material having a hole-transporting property of the composite material. Specifically, the HOMO level is preferably from −5.7 eV to −5.4 eV. This can facilitate injection of holes into the unit 103 or the layer 112. Alternatively, the reliability of the light-emitting device can be improved.

[0234] Examples of compounds having an aromatic amine skeleton that can be used include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0235] Examples of the carbazole derivative include 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole, and carbazole (abbreviation: PCzPCN1), 4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, and the like can be used.

[0236] Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9,10 10,10'-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, pentacene, coronene, and the like can be used.

[0237] Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA), and the like.

[0238] Examples of polymer compounds that can be used include poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD).

[0239] For example, a substance having a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton can be suitably used as a material having hole transport properties for the composite material. Furthermore, a substance having an aromatic amine with a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine with a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group can be used as a material having hole transport properties for the composite material. The use of a substance having an N,N-bis(4-biphenyl)amino group can improve the reliability of the light-emitting device.

[0240] Examples of these materials 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: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-0 3), 4,4'-diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-Diphenyl-4''-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4' 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(1, 1'-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([1,1'-biphenyl-4-yl]amine N,N-bis([1,1′-biphenyl]-4-yl)-9,9′-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis([1,1′-biphenyl]-4-yl)-9,9′-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(1,1′-biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)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]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), N-(1,1'-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 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, and the like can be used.

[0241] [Configuration Example 2 of Composite Material] For example, a composite material containing a substance having an acceptor property, a material having a hole-transport property, and an alkali metal fluoride or an alkaline earth metal fluoride can be used as a material having a hole-injection property. In particular, a composite material containing fluorine atoms at an atomic ratio of 20% or more can be preferably used. This can reduce the refractive index of the layer 111. Alternatively, a layer with a low refractive index can be formed inside the light-emitting device. Alternatively, the external quantum efficiency of the light-emitting device can be improved.

[0242] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0243] Embodiment 4 In this embodiment, a structure of a light-emitting device 150 of one embodiment of the present invention will be described with reference to FIG. 1A.

[0244] <Configuration Example of Light-Emitting Device 150> The light-emitting device 150 described in this embodiment includes an electrode 101, an electrode 102, a unit 103, and a layer 105. The electrode 102 has a region overlapping with the electrode 101, and the unit 103 has a region sandwiched between the electrode 101 and the electrode 102. The layer 105 has a region sandwiched between the unit 103 and the electrode 102. Note that the structure described in Embodiment 2 can be used for the unit 103, for example.

[0245] <Structure example of electrode 102> For example, a conductive material can be used for the electrode 102. Specifically, a metal, an alloy, a conductive compound, or a mixture thereof can be used for the electrode 102. For example, a material having a work function smaller than that of the electrode 101 can be suitably used for the electrode 102. Specifically, a material having a work function of 3.8 eV or less is preferred.

[0246] For example, the electrode 102 can be made of elements belonging to Group 1 of the periodic table, elements belonging to Group 2 of the periodic table, rare earth metals, and alloys containing these.

[0247] Specifically, lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), strontium (Sr), europium (Eu), ytterbium (Yb), and alloys containing these (MgAg, AlLi) can be used for the electrode 102.

[0248] <Structure Example of Layer 105> For example, a material having an electron injecting property can be used for the layer 105. The layer 105 can also be referred to as an electron injecting layer.

[0249] Specifically, a substance having donor properties can be used for the layer 105. Alternatively, a composite material of a substance having donor properties and a material having electron transport properties can be used for the layer 105. Alternatively, an electride can be used for the layer 105. This can facilitate injection of electrons from the electrode 102, for example. Alternatively, not only a material having a low work function but also a material having a high work function can be used for the electrode 102. Alternatively, a material for the electrode 102 can be selected from a wide range of materials regardless of the work function. Specifically, Al, Ag, ITO, indium oxide-tin oxide containing silicon or silicon oxide, or the like can be used for the electrode 102. Alternatively, the driving voltage of the light-emitting device can be reduced.

[0250] [Substance Having Donor Properties] For example, alkali metals, alkaline earth metals, rare earth metals, or compounds thereof (oxides, halides, carbonates, etc.) can be used as the substance having donor properties. Alternatively, organic compounds such as tetrathianaphthacene (abbreviation: TTN), nickelocene, and decamethylnickelocene can also be used as the substance having donor properties.

[0251] Examples of alkali metal compounds (including oxides, halides, and carbonates) that can be used include lithium oxide, lithium fluoride (LiF), cesium fluoride (CsF), lithium carbonate, cesium carbonate, and 8-hydroxyquinolinato-lithium (abbreviated as Liq).

[0252] Alkaline earth metal compounds (including oxides, halides, and carbonates) include calcium fluoride (CaF ２), etc. can be used.

[0253] [Configuration Example 1 of Composite Material] A composite material of a plurality of substances can be used as a material having an electron injecting property. For example, a material having a donor property and a material having an electron transport property can be used as a composite material.

[0254] For example, a metal complex or an organic compound having a π-electron-deficient heteroaromatic ring skeleton can be used as the material having an electron-transporting property of the composite material. For example, the material having an electron-transporting property that can be used for the unit 103 can be used for the composite material.

[0255] [Configuration Example 2 of Composite Material] A microcrystalline alkali metal fluoride and a material having an electron-transporting property can be used for the composite material. Alternatively, a microcrystalline alkaline earth metal fluoride and a material having an electron-transporting property can be used for the composite material. In particular, a composite material containing 50 wt % or more of an alkali metal fluoride or an alkaline earth metal fluoride can be preferably used. Alternatively, a composite material containing an organic compound having a bipyridine skeleton can be preferably used. This can reduce the refractive index of the layer 104. Alternatively, the external quantum efficiency of the light-emitting device can be improved.

[0256] [Electride] For example, a substance in which electrons are added to a mixed oxide of calcium and aluminum at a high concentration can be used as a material having electron injection properties.

[0257] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0258] Embodiment 5 In this embodiment, a structure of a light-emitting device 150 of one embodiment of the present invention will be described with reference to FIG. 3A.

[0259] FIG. 3A is a cross-sectional view illustrating a structure of a light-emitting device according to one embodiment of the present invention.

[0260] <Configuration Example of Light-Emitting Device 150> Furthermore, light-emitting device 150 described in this embodiment has electrode 101, electrode 102, unit 103, and intermediate layer 106 (see FIG. 3A ). Electrode 102 has a region overlapping with electrode 101, and unit 103 has a region sandwiched between electrode 101 and electrode 102. Intermediate layer 106 has a region sandwiched between unit 103 and electrode 102.

[0261] <<Configuration Example of Intermediate Layer 106>> The intermediate layer 106 includes a layer 106 A and a layer 106 B. The layer 106 B includes a region sandwiched between the layer 106 A and the electrode 102.

[0262] <<Configuration Example of Layer 106A>> For example, a material having electron transport properties can be used for the layer 106A. The layer 106A can also be referred to as an electron relay layer. By using the layer 106A, the layer in contact with the anode side of the layer 106A can be separated from the layer in contact with the cathode side of the layer 106A. The interaction between the layer in contact with the anode side of the layer 106A and the layer in contact with the cathode side of the layer 106A can be reduced. Electrons can be smoothly supplied to the layer in contact with the anode side of the layer 106A.

[0263] A substance having a LUMO level between the LUMO level of a substance having acceptor properties included in a layer in contact with the anode side of the layer 106A and the LUMO level of a substance included in a layer in contact with the cathode side of the layer 106A can be suitably used for the layer 106A.

[0264] For example, a material having a LUMO level in the range of −5.0 eV or more, preferably −5.0 eV or more and −3.0 eV or less, can be used for the layer 106A.

[0265] Specifically, a phthalocyanine-based material can be used for the layer 106A, or a metal complex having a metal-oxygen bond and an aromatic ligand can be used for the layer 106A.

[0266] <<Configuration Example of Layer 106B>> For example, a material that supplies electrons to the anode side and holes to the cathode side when a voltage is applied can be used for the layer 106B. Specifically, it can supply electrons to the unit 103 arranged on the anode side. The layer 106B can also be called a charge generation layer.

[0267] Specifically, the material having a hole-injecting property that can be used for the layer 104 can be used for the layer 106B. For example, a composite material can be used for the layer 106B. Alternatively, for example, a stacked film in which a film including the composite material and a film including a material having a hole-transporting property are stacked can be used for the layer 106B.

[0268] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0269] Embodiment 6 In this embodiment, a structure of a light-emitting device 150 of one embodiment of the present invention will be described with reference to FIG. 3B.

[0270] FIG. 3B is a cross-sectional view illustrating a structure of a light-emitting device according to one embodiment of the present invention, which has a structure different from that illustrated in FIG. 3A.

[0271] <Configuration Example of Light-Emitting Device 150> The light-emitting device 150 described in this embodiment has an electrode 101, an electrode 102, a unit 103, an intermediate layer 106, and a unit 103(12) (see FIG. 3B ). The electrode 102 has a region overlapping with the electrode 101, the unit 103 has a region sandwiched between the electrodes 101 and 102, and the intermediate layer 106 has a region sandwiched between the unit 103 and the electrode 102. Furthermore, the unit 103(12) has a region sandwiched between the intermediate layer 106 and the electrode 102, and the unit 103(12) has a function of emitting light EL1(2).

[0272] A configuration including the intermediate layer 106 and multiple units is sometimes called a stacked light-emitting device or a tandem light-emitting device. This allows for high-luminance light emission while maintaining a low current density. Alternatively, it can improve reliability. Alternatively, it can reduce the driving voltage compared with the same luminance. Alternatively, it can reduce power consumption.

[0273] <<Configuration Example of Unit 103 (12)>> The configuration that can be used for the unit 103 can be used for the unit 103 (12). In other words, the light-emitting device 150 has a plurality of stacked units. Note that the number of stacked units is not limited to two, and three or more units can be stacked.

[0274] The same configuration as unit 103 can be used for unit 103(12), or a different configuration from unit 103 can be used for unit 103(12).

[0275] For example, a configuration having an emission color different from that of the unit 103 (12) can be used. Specifically, a unit 103 that emits red light and green light and a unit 103 (12) that emits blue light can be used. This makes it possible to provide a light-emitting device that emits light of a desired color. For example, it is possible to provide a light-emitting device that emits white light.

[0276] The intermediate layer 106 has a function of supplying electrons to one of the unit 103 and the unit 103(12) and supplying holes to the other. For example, the intermediate layer 106 described in Embodiment 5 can be used.

[0277] <Method for manufacturing the light-emitting device 150> For example, the electrode 101, the electrode 102, the unit 103, the intermediate layer 106, and the unit 103(12) can be formed by using a dry method, a wet method, a vapor deposition method, a droplet discharge method, a coating method, a printing method, etc. Also, different methods can be used to form each component.

[0278] Specifically, the light-emitting device 150 can be produced using a vacuum deposition device, an inkjet device, a coating device such as a spin coater, a gravure printing device, an offset printing device, a screen printing device, or the like.

[0279] For example, an electrode can be formed by a wet method using a paste of a metal material or a sol-gel method. Also, an indium oxide-zinc oxide film can be formed by a sputtering method using a target containing 1 wt % to 20 wt % of zinc oxide added to indium oxide. Also, an indium oxide (IWZO) film containing tungsten oxide and zinc oxide can be formed by a sputtering method using a target containing 0.5 wt % to 5 wt % of tungsten oxide and 0.1 wt % to 1 wt % of zinc oxide added to indium oxide.

[0280] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0281] Embodiment 7 In this embodiment, a structure of a functional panel 700 according to one embodiment of the present invention will be described with reference to FIGS. 4A and 4B. FIG.

[0282] FIG. 4A is a cross-sectional view illustrating a configuration of a functional panel 700 according to one embodiment of the present invention, and FIG. 4B is a cross-sectional view illustrating a configuration of the functional panel 700 according to another embodiment of the present invention that is different from that illustrated in FIG. 4A.

[0283] <Configuration Example 1 of Functional Panel 700> The functional panel 700 described in this embodiment includes a light-emitting device 150 and a light-emitting device 150(2) (see FIG. 4A).

[0284] The functional panel 700 has an insulating film 528 (see FIG. 4A). The insulating film 528 has openings, one of which overlaps with the electrode 101 and the other of which overlaps with the electrode 101(2).

[0285] <Configuration Example 2 of Functional Panel 700> The functional panel 700 also has, for example, an insulating film 573 (see FIG. 4B ). The insulating film 573 includes an insulating film 573A and an insulating film 573B, and the insulating film 573A includes a region sandwiched between the insulating film 573B and the insulating film 521.

[0286] Furthermore, unit 103(2) has a groove between it and unit 103, and unit 103(2) has a sidewall along the groove. Furthermore, unit 103 also has a sidewall along the groove.

[0287] The insulating film 573A has a region in contact with the side wall of the unit 103(2) and a region in contact with the side wall of the unit 103.

[0288] For example, the light-emitting devices described in any of the first to sixth embodiments can be used as the light-emitting device 150 .

[0289] <Configuration Example of Light-Emitting Device 150(2)> The light-emitting device 150(2) described in this embodiment includes an electrode 101(2), an electrode 102, and a unit 103(2) (see FIG. 4A). The electrode 102 has an area overlapping with the electrode 101(2), and the unit 103(2) has an area sandwiched between the electrode 101(2) and the electrode 102.

[0290] The electrode 101(2) may be at the same potential as or a different potential from the electrode 101. By supplying a different potential, the light-emitting device 150(2) can be driven under different conditions from the light-emitting device 150. Note that the materials that can be used for the electrode 101 can also be used for the electrode 101(2).

[0291] The light-emitting device 150(2) also includes a layer 104 and a layer 105. The layer 104 includes a region sandwiched between the electrode 101(2) and the unit 103(2), and the layer 105 includes a region sandwiched between the unit 103(2) and the electrode 102. Note that part of the configuration of the light-emitting device 150 can be used as part of the configuration of the light-emitting device 150(2). This allows part of the configuration to be shared, or the manufacturing process can be simplified.

[0292] <Configuration Example of Unit 103(2)> The unit 103(2) has a single-layer structure or a laminated structure. The unit 103(2) has, for example, a layer 111(2), a layer 112, and a layer 113 (see FIG. 4A). The unit 103(2) also has, for example, a layer 111(2), a layer 112(2), and a layer 113(2) (see FIG. 4B). Note that the layer 112(2) has a structure that can be used for the layer 112, and the layer 113(2) has a structure that can be used for the layer 113.

[0293] Layer 111(2) comprises an area sandwiched between layers 112 and 113, layer 112 comprises an area sandwiched between electrode 101(2) and layer 111(2), and layer 113 comprises an area sandwiched between electrode 102 and layer 111(2).

[0294] For example, the unit 103(2) may include a layer selected from functional layers such as a light-emitting layer, a hole-transporting layer, an electron-transporting layer, a carrier-blocking layer, etc. Also, the unit 103(2) may include a layer selected from functional layers such as a hole-injecting layer, an electron-injecting layer, an exciton-blocking layer, and a charge-generating layer.

[0295] <<Structure Example 1 of Layer 111(2)>> For example, a light-emitting material or a light-emitting material and a host material can be used for the layer 111(2). The layer 111(2) can also be referred to as a light-emitting layer. Note that a structure in which the layer 111(2) is disposed in a region where holes and electrons recombine can be preferred. This allows the energy generated by carrier recombination to be efficiently converted into light and emitted. Furthermore, a structure in which the layer 111(2) is disposed away from metals used for electrodes, etc. can be preferred. This can suppress the quenching phenomenon caused by metals used for electrodes, etc.

[0296] For example, a light-emitting material different from the light-emitting material used in the layer 111 can be used in the layer 111(2). Specifically, light-emitting materials with different emission colors can be used in the layer 111(2). This allows light-emitting devices with different hues to be arranged. Alternatively, additive color mixing can be performed using multiple light-emitting devices with different hues. Alternatively, colors with hues that cannot be displayed by individual light-emitting devices can be displayed.

[0297] For example, a light emitting device that emits blue light, a light emitting device that emits green light, and a light emitting device that emits red light can be arranged on the functional panel, or a light emitting device that emits white light, a light emitting device that emits yellow light, and a light emitting device that emits infrared light can be arranged on the functional panel.

[0298] <<Structure Example 2 of Layer 111(2)>> For example, a fluorescent material, a phosphorescent material, or a material exhibiting thermally activated delayed fluorescence (TADF material) can be used as the light-emitting material, which allows energy generated by carrier recombination to be emitted from the light-emitting material as light EL2 (see FIG. 4A ).

[0299] [Fluorescent Material] A fluorescent material can be used for the layer 111(2). For example, the fluorescent materials exemplified below can be used for the layer 111(2). Note that the fluorescent material is not limited thereto, and various known fluorescent materials can be used for the layer 111(2).

[0300] Specifically, 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-butyl)perylene (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: 2PAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAB PhA), 9,10-bis(1,1'-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(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6 -methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine amine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)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: BisDCJ™), N,N'-(pyren-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1 ,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02), 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02), and the like can be used.

[0301] In particular, condensed aromatic diamine compounds typified by pyrenediamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 are preferred because they have high hole trapping properties and are excellent in luminous efficiency or reliability.

[0302] [Phosphorescent Material] A phosphorescent material can be used for the layer 111(2). For example, the phosphorescent materials exemplified below can be used for the layer 111(2). Note that the present invention is not limited to these materials, and various known phosphorescent materials can be used for the layer 111(2).

[0303] For example, organometallic iridium complexes having a 4H-triazole skeleton, organometallic iridium complexes having a 1H-triazole skeleton, organometallic iridium complexes having an imidazole skeleton, organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand, organometallic iridium complexes having a pyrimidine skeleton, organometallic iridium complexes having a pyrazine skeleton, organometallic iridium complexes having a pyridine skeleton, rare earth metal complexes, platinum complexes, or the like can be used for the layer 111(2).

[0304] [Phosphorescent material (blue)] Examples of organometallic iridium complexes having a 4H-triazole skeleton include 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 ]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz) ３ ]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b) ３ ]), etc. can be used.

[0305] Examples of organometallic iridium complexes having a 1H-triazole skeleton include tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp) ３ ]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me) ３ ]), etc. can be used.

[0306] Examples of organometallic iridium complexes having an imidazole skeleton include fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpmi) ３ ]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me) ３ ]), etc. can be used.

[0307] Examples of organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand include bis[2-(4',6'-difluorophenyl)pyridinato-N,C ２’]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C ２’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C ２’} Iridium(III) picolinate (abbreviation: [Ir(CF ３ ppy) ２ (pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C ２’ ] Iridium (III) acetylacetonate (abbreviation: FIracac), etc. can be used.

[0308] These compounds exhibit blue phosphorescence and have a peak emission wavelength in the range of 440 nm to 520 nm.

[0309] [Phosphorescent Material (Green)] Examples of organometallic iridium complexes having a pyrimidine skeleton include 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)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)２ (acac)]), etc. can be used.

[0310] Examples of organometallic iridium complexes having a pyrazine skeleton include (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me) ２ (acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr) ２ (acac)]), etc. can be used.

[0311] Examples of organometallic iridium complexes having a pyridine skeleton include 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-d ３ -methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d ３ -methyl-2-pyridinyl-κN ２ )phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy-d ３ ) ２ (mbfpypy-d ３ ) )]), [2-d ３[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy) ２ (mbfpypy-d ３ ) )]), etc. can be used.

[0312] The rare earth metal complexes include tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac) ３ (Phen)]), etc.

[0313] These compounds mainly exhibit green phosphorescence, with a peak emission wavelength between 500 nm and 600 nm. Organometallic iridium complexes having a pyrimidine skeleton are also remarkably superior in reliability and luminous efficiency.

[0314] [Phosphorescent material (red)] Examples of organometallic iridium complexes having a pyrimidine skeleton include (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)]), bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(dpm) ２ (dpm)]), etc. can be used.

[0315] Examples of organometallic iridium complexes having a pyrazine skeleton include (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr) ２ (acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr) ２ (dpm)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)２ (acac)]), etc. can be used.

[0316] Examples of organometallic iridium complexes having a pyridine skeleton include 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)]), etc. can be used.

[0317] Examples of rare earth metal complexes include tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM) ３ (Phen)]), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA) ３ (Phen)]), etc. can be used.

[0318] As the platinum complex, 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP) and the like can be used.

[0319] These compounds exhibit red phosphorescence, with an emission peak at 600 nm to 700 nm. The organometallic iridium complexes having a pyrazine skeleton emit red light with a chromaticity suitable for use in display devices.

[0320] [Substances Exhibiting Thermally Activated Delayed Fluorescence (TADF)] A TADF material can be used for the layer 111(2). The TADF material has a small difference between the S1 level and the T1 level, and can reverse intersystem crossing (upconversion) from a triplet excited state to a singlet excited state with a small amount of thermal energy. This allows efficient generation of a singlet excited state from a triplet excited state. Furthermore, the triplet excited energy can be converted into luminescence.

[0321] Furthermore, an exciplex (also called an exciplex) that forms an excited state with two types of substances has an extremely small difference between the S1 level and the T1 level, and functions as a TADF material that can convert triplet excitation energy into singlet excitation energy.

[0322] The T1 level can be determined by using a phosphorescence spectrum observed at low temperatures (e.g., 77 K to 10 K). When a tangent line is drawn at the base of the fluorescence spectrum located at the shortest wavelength and the energy of the wavelength of the extrapolated line is defined as the S1 level, and when a tangent line is drawn at the base of the phosphorescence spectrum located at the shortest wavelength and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between the S1 level and the T1 level is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0323] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0324] For example, the TADF material which can be used as the host material described in Embodiment 1 can be used as the light-emitting material.

[0325] <<Structure Example 3 of Layer 111(2)>> A material having carrier transport properties can be used as the host material. For example, a material having hole transport properties, a material having electron transport properties, a substance exhibiting thermally activated delayed fluorescence, a material having an anthracene skeleton, a mixed material, or the like can be used as the host material. Note that a structure using a material having a larger band gap than the light-emitting material contained in the layer 111(2) as the host material is preferable. This can suppress energy transfer from excitons generated in the layer 111(2) to the host material.

[0326] [Material having hole transport properties] A material having a hole mobility of 1×10 −６ cm ２ A material having a hole transporting property can be suitably used as a material having a hole transporting property.

[0327] For example, a material having a hole-transport property that can be used for the layer 112 can be used for the layer 111(2). Specifically, a material having a hole-transport property that can be used for a hole-transport layer can be used for the layer 111(2).

[0328] [Material Having Electron-Transporting Properties] For example, a material having electron-transporting properties that can be used for the layer 113 can be used for the layer 111(2). Specifically, a material having electron-transporting properties that can be used for an electron-transport layer can be used for the layer 111(2).

[0329] [Materials Having an Anthracene Skeleton] Organic compounds having an anthracene skeleton can be used as host materials. In particular, when a fluorescent material is used as the light-emitting material, organic compounds having an anthracene skeleton are suitable. This allows for the realization of light-emitting devices with good luminous efficiency and durability.

[0330] As the organic compound having an anthracene skeleton, an organic compound having a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton, is preferred because it is chemically stable. Furthermore, when the host material has a carbazole skeleton, it is preferred because it has improved hole injection and transport properties. In particular, when the host material contains a dibenzocarbazole skeleton, it is preferred because its HOMO level is shallower by about 0.1 eV than that of carbazole, making it easier for holes to enter, and it also has excellent hole transport properties and high heat resistance. From the viewpoint of hole injection and transport properties, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton.

[0331] Therefore, a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton, a substance having both a 9,10-diphenylanthracene skeleton and a benzocarbazole skeleton, or a substance having both a 9,10-diphenylanthracene skeleton and a dibenzocarbazole skeleton is preferable as the host material.

[0332] For example, 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-phenyl-3-[4-(10-phenyl [4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 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), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), and the like can be used.

[0333] In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA exhibit very good properties.

[0334] [Configuration Example 1 of Mixed Material] A material obtained by mixing a plurality of substances can be used as the host material. For example, a material having electron transport properties and a material having hole transport properties can be used as the mixed material. The weight ratio of the material having hole transport properties to the material having electron transport properties contained in the mixed material (material having hole transport properties / material having electron transport properties) may be set to (1 / 19) or more and (19 / 1) or less. This allows the carrier transport properties of the layer 111(2) to be easily adjusted. Furthermore, the recombination region can be easily controlled.

[0335] [Configuration Example 2 of Mixed Material] A material mixed with a phosphorescent material can be used as a host material. When a fluorescent material is used as an emitting material, the phosphorescent material can be used as an energy donor that provides excitation energy to the fluorescent material.

[0336] A mixed material containing a material that forms an exciplex can be used as the host material. For example, a material whose emission spectrum of the formed exciplex overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material can be used as the host material. This allows smooth energy transfer, improving light-emitting efficiency. Alternatively, the driving voltage can be reduced. With this structure, light emission can be efficiently obtained using Exciplex-Triple Energy Transfer (ExTET), which is energy transfer from the exciplex to the light-emitting material (phosphorescent material).

[0337] At least one of the materials forming the exciplex can be a phosphorescent material, which allows for the utilization of reverse intersystem crossing or the efficient conversion of triplet excitation energy to singlet excitation energy.

[0338] As a combination of materials for forming an exciplex, it is preferable that the HOMO level of the material having hole transport properties is equal to or higher than the HOMO level of the material having electron transport properties. Alternatively, it is preferable that the LUMO level of the material having hole transport properties is equal to or higher than the LUMO level of the material having electron transport properties. This allows for efficient formation of an exciplex. The LUMO level and HOMO level of the material can be derived from electrochemical properties (reduction potential and oxidation potential). Specifically, the reduction potential and oxidation potential can be measured using cyclic voltammetry (CV) measurement.

[0339] The formation of exciplexes can be confirmed, for example, by comparing the emission spectra of a material having hole transport properties, a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing the phenomenon in which the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak on the longer wavelength side). Alternatively, the formation of exciplexes can be confirmed by comparing the transient photoluminescence (PL) of a material having hole transport properties, the transient PL of a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lifetime component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL may also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of a material having hole transport properties, the transient EL of a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing the differences in transient response.

[0340] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0341] Embodiment 8 In this embodiment, a structure of a functional panel 700 according to one embodiment of the present invention will be described with reference to FIG.

[0342] <Configuration Example 1 of Functional Panel 700> The functional panel 700 described in this embodiment has a light-emitting device 150 and an optical functional device 170 (see FIG. 5A).

[0343] For example, the light-emitting devices described in any of the first to sixth embodiments can be used as the light-emitting device 150 .

[0344] <Configuration Example of Optical Functional Device 170> The optical functional device 170 described in this embodiment has an electrode 101S, an electrode 102, and a unit 103S. The electrode 102 has an area overlapping with the electrode 101S, and the unit 103S has an area sandwiched between the electrode 101S and the electrode 102.

[0345] The optical functional device 170 also includes a layer 104 and a layer 105. The layer 104 includes a region sandwiched between the electrode 101S and the unit 103S, and the layer 105 includes a region sandwiched between the unit 103S and the electrode 102. Note that part of the configuration of the light-emitting device 150 can be used as part of the configuration of the optical functional device 170. This allows part of the configuration to be shared, or simplifies the manufacturing process.

[0346] <Configuration Example 1 of Unit 103S> The unit 103S has a single-layer structure or a laminated structure. For example, the unit 103S includes a layer 114, a layer 112, and a layer 113 (see FIG. 5A).

[0347] Layer 114 comprises a region sandwiched between layers 112 and 113, layer 112 comprises a region sandwiched between electrode 101S and layer 114, and layer 113 comprises a region sandwiched between electrode 102 and layer 114.

[0348] For example, the unit 103S may include a layer selected from functional layers such as a photoelectric conversion layer, a hole transport layer, an electron transport layer, and a carrier blocking layer. The unit 103S may also include a layer selected from functional layers such as an exciton blocking layer and a charge generating layer.

[0349] The unit 103S absorbs light hv and supplies electrons to one electrode and holes to the other electrode. For example, the unit 103S supplies holes to the electrode 101S and electrons to the electrode 102.

[0350] <Structure Example of Layer 112> For example, a material having a hole-transport property can be used for the layer 112. The layer 112 can be referred to as a hole-transport layer. For example, the structure described in Embodiment 2 can be used for the layer 112.

[0351] <Structure Example of Layer 113> For example, a material having an electron-transporting property, a material having an anthracene skeleton, a mixed material, or the like can be used for the layer 113. For example, the structure described in Embodiment 2 can be used for the layer 113.

[0352] <<Configuration Example 1 of Layer 114>> For example, an electron-accepting material and an electron-donating material can be used for the layer 114. Specifically, a material that can be used for an organic solar cell can be used for the layer 114. The layer 114 can also be referred to as a photoelectric conversion layer. The layer 114 absorbs light hv and supplies electrons to one electrode and holes to the other electrode. For example, the layer 114 supplies holes to the electrode 101S and electrons to the electrode 102.

[0353] [Examples of Electron Accepting Materials] For example, fullerene derivatives, non-fullerene electron acceptors, etc. can be used as the electron accepting material.

[0354] As the electron-accepting material, C ６０ Fullerene, C ７０ Fullerene, [6,6]-phenyl-C ７１ -Butyric acid methyl ester (abbreviation: PC71BM), [6,6]-phenyl-C ６１ -butyric acid methyl ester (abbreviation: PC61BM), 1',1'',4',4''-tetrahydro-di[1,4]methanonaphthaleno[1,2:2',3',56,60:2'',3''][5,6]fullerene-C ６０ (abbreviation: ICBA) etc. can be used.

[0355] Examples of non-fullerene electron acceptors that can be used include perylene derivatives, compounds having a dicyanomethyleneindanone group, and N,N'-dimethyl-3,4,9,10-perylenedicarboximide (abbreviation: Me-PTCDI).

[0356] [Examples of Electron-Donating Materials] For example, phthalocyanine compounds, tetracene derivatives, quinacridone derivatives, rubrene derivatives, etc. can be used as electron-donating materials.

[0357] Examples of electron-donating materials that can be used include copper (II) phthalocyanine (abbreviation: CuPc), tin (II) phthalocyanine (abbreviation: SnPc), zinc phthalocyanine (abbreviation: ZnPc), tetraphenyldibenzoperiflanthene (abbreviation: DBP), and rubrene.

[0358] <<Structure Example 2 of Layer 114>> For example, a single layer structure or a stacked layer structure can be used for the layer 114. Specifically, a bulk heterojunction structure can be used for the layer 114. Alternatively, a heterojunction structure can be used for the layer 114.

[0359] [Configuration Example of Mixed Material] For example, a mixed material containing an electron-accepting material and an electron-donating material can be used for the layer 114 (see FIG. 5A ). Note that a structure in which a mixed material containing an electron-accepting material and an electron-donating material is used for the layer 114 can be referred to as a bulk heterojunction type.

[0360] Specifically, C ７０ A composite material including fullerenes and DBPs can be used for layer 114 .

[0361] [Example of Heterojunction Type] Layer 114N and layer 114P can be used for layer 114. Layer 114N includes a region sandwiched between one electrode and layer 114P, and layer 114P includes a region sandwiched between layer 114N and the other electrode. For example, layer 114N includes a region sandwiched between electrode 102 and layer 114P, and layer 114P includes a region sandwiched between layer 114N and electrode 101S (see FIG. 5B ).

[0362] An n-type semiconductor can be used for the layer 114N. For example, Me-PTCDI can be used for the layer 114N.

[0363] Alternatively, a p-type semiconductor can be used for the layer 114P. For example, rubrene can be used for the layer 114P.

[0364] The optical functional device 170 having a configuration in which the layer 114P is in contact with the layer 114N can be called a PN junction photodiode.

[0365] <Configuration Example 2 of Unit 103S> The unit 103S includes a layer 111(2), which includes a region sandwiched between the layer 114 and the layer 113 (see FIG. 5C).

[0366] Configuration example 2 of unit 103S differs from configuration example 1 of unit 103S in that it includes layer 111(2). Here, the differences will be described in detail, and the above description will be used for the parts that have the same configuration.

[0367] <<Configuration Example of Layer 111(2)>> For example, a light-emitting material or a light-emitting material and a host material can be used for the layer 111(2). The layer 111(2) can also be referred to as a light-emitting layer. Note that a configuration in which the layer 111(2) is disposed in a region where holes and electrons recombine can be preferred. This allows the energy generated by carrier recombination to be efficiently converted into light and emitted. Furthermore, a configuration in which the layer 111(2) is disposed away from metals used for electrodes, etc. can be preferred. This can suppress the quenching phenomenon caused by metals used for electrodes, etc.

[0368] Specifically, the structure described in the seventh embodiment can be used for the layer 111(2). In particular, a structure that emits light with a wavelength that is not easily absorbed by the layer 114 can be suitably used for the layer 111(2). This allows the light EL2 emitted by the layer 111(2) to be extracted with high efficiency.

[0369] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0370] Embodiment Mode 9 In this embodiment mode, a light-emitting device using the light-emitting device described in any one of Embodiment Modes 1 to 6 will be described.

[0371] In this embodiment, a light-emitting device manufactured using the light-emitting device described in any one of Embodiments 1 to 6 will be described with reference to Fig. 6. Fig. 6A is a top view showing the light-emitting device, and Fig. 6B is a cross-sectional view taken along lines A-B and C-D in Fig. 6A. This light-emitting device includes a driver circuit section (source line driver circuit 601), a pixel section 602, and a driver circuit section (gate line driver circuit 603) indicated by dotted lines to control light emission from the light-emitting device. Also, 604 denotes a sealing substrate, 605 denotes a sealant, and the inside surrounded by the sealant 605 forms a space 607.

[0372] The routing wiring 608 is wiring for transmitting signals input to the source line driver circuit 601 and the gate line driver circuit 603, and receives video signals, clock signals, start signals, reset signals, etc. from an FPC (flexible printed circuit) 609, which serves as an external input terminal. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to this FPC. In this specification, the light-emitting device includes not only the light-emitting device itself but also a state in which an FPC or PWB is attached to it.

[0373] Next, the cross-sectional structure will be described with reference to Fig. 6B. A driver circuit portion and a pixel portion are formed on an element substrate 610, and here, a source line driver circuit 601, which is the driver circuit portion, and one pixel in a pixel portion 602 are shown.

[0374] The element substrate 610 may be made of a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or the like, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, or the like.

[0375] The structure of a transistor used in a pixel or a driver circuit is not particularly limited. For example, an inverted staggered transistor or a staggered transistor may be used. Furthermore, a top-gate transistor or a bottom-gate transistor may be used. The semiconductor material used for the transistor is not particularly limited, and examples thereof include silicon, germanium, silicon carbide, and gallium nitride. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In—Ga—Zn-based metal oxide, may be used.

[0376] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0377] Here, it is preferable to use an oxide semiconductor for the transistors provided in the pixel or the driver circuit, as well as for semiconductor devices such as transistors used in touch sensors, which will be described later. In particular, it is preferable to use an oxide semiconductor having a wider band gap than silicon. By using an oxide semiconductor having a wider band gap than silicon, the current in the off state of the transistor can be reduced.

[0378] The oxide semiconductor preferably contains at least indium (In) or zinc (Zn), and more preferably contains an oxide represented by In-M-Zn-based oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0379] In particular, it is preferable to use, as the semiconductor layer, an oxide semiconductor film which has a plurality of crystal parts whose c-axes are oriented perpendicular to a surface on which the semiconductor layer is formed or a top surface of the semiconductor layer and which does not have grain boundaries between adjacent crystal parts.

[0380] By using such a material for the semiconductor layer, fluctuations in electrical characteristics are suppressed, and a highly reliable transistor can be realized.

[0381] Furthermore, a transistor having the above-described semiconductor layer can retain charge stored in a capacitor through the transistor for a long period of time due to its low off-state current. By applying such a transistor to a pixel, it is possible to stop the driver circuit while maintaining the gray level of an image displayed in each display region. As a result, an electronic device with extremely low power consumption can be realized.

[0382] For example, to stabilize the characteristics of a transistor, it is preferable to provide a base film. The base film can be formed as a single layer or a stacked layer 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 CVD (Chemical Vapor Deposition) method (such as a plasma CVD method, a thermal CVD method, or a MOCVD (Metal Organic CVD) method), an ALD (Atomic Layer Deposition) method, a coating method, a printing method, or the like. Note that the base film need not be provided if it is not necessary.

[0383] Note that the FET 623 represents one of the transistors formed in the source line driver circuit 601. The driver circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. In addition, although this embodiment shows a driver-integrated type in which the driver circuit is formed on a substrate, this is not necessarily required, and the driver circuit may also be formed externally rather than on the substrate.

[0384] Furthermore, the pixel portion 602 is formed by a plurality of pixels including a switching FET 611, a current control FET 612, and a first electrode 613 electrically connected to the drain of the FET, but is not limited to this, and the pixel portion may be formed by combining three or more FETs and a capacitance element.

[0385] An insulator 614 is formed to cover an end portion of the first electrode 613. Here, the insulator 614 can be formed by using a positive photosensitive acrylic resin film.

[0386] Furthermore, in order to improve the coverage of an EL layer or the like to be formed later, a curved surface having a curvature is formed at the upper or lower end of the insulator 614. For example, when a positive photosensitive acrylic resin is used as the material of the insulator 614, it is preferable that only the upper end of the insulator 614 has a curved surface having a curvature radius (0.2 μm or more and 3 μm or less). Furthermore, either a negative photosensitive resin or a positive photosensitive resin can be used as the insulator 614.

[0387] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, it is desirable to use a material with a large work function as the material used for the first electrode 613, which functions as an anode. For example, a single layer film such as 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, or a Pt film can be used. It is also possible to use a stacked structure of a titanium nitride film and a film mainly composed of aluminum, or a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film. The stacked structure provides low resistance as a wiring, good ohmic contact, and the first electrode 613 can function as an anode.

[0388] The EL layer 616 is formed by various methods such as an evaporation method using an evaporation mask, an ink-jet method, or a spin coating method. The EL layer 616 has the structure described in any one of Embodiments 1 to 6. Other materials forming the EL layer 616 may be low-molecular-weight compounds or high-molecular-weight compounds (including oligomers and dendrimers).

[0389] Furthermore, as a material used for the second electrode 617 formed on the EL layer 616 and functioning as a cathode, a material having a small work function (Al, Mg, Li, Ca, or an alloy or compound thereof (MgAg, MgIn, AlLi, etc.)) is preferably used. Note that, when light generated in the EL layer 616 is transmitted through the second electrode 617, it is preferable to use a stack of a thin metal thin film and a transparent conductive film (ITO, indium oxide containing 2 wt % to 20 wt % zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) as the second electrode 617.

[0390] Note that a light-emitting device 618 is formed with the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting device is the light-emitting device described in any one of Embodiments 1 to 6. Note that a plurality of light-emitting devices are formed in a pixel portion, and the light-emitting device in this embodiment may include both the light-emitting device described in any one of Embodiments 1 to 6 and light-emitting devices having other structures.

[0391] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with a sealing material 605, a structure is formed in which a light-emitting device 618 is provided in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. The space 607 is filled with a filler, and in some cases, the space is filled with an inert gas (nitrogen, argon, etc.), or with a sealing material. A recess is formed in the sealing substrate, and by providing a desiccant therein, deterioration due to the influence of moisture can be suppressed, which is a preferable configuration.

[0392] It is preferable to use an epoxy resin or glass frit for the sealing material 605. It is also desirable that these materials be moisture and oxygen impermeable as much as possible. The sealing substrate 604 may be made of a glass substrate, a quartz substrate, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, or the like.

[0393] Although not shown in Figures 6A and 6B, a protective film may be provided on the second electrode. The protective film may be formed of an organic resin film or an inorganic insulating film. The protective film may also be formed so as to cover the exposed portion of the sealing material 605. The protective film may also be provided so as to cover the surfaces and side surfaces of the pair of substrates, the exposed side surfaces of the sealing layer, the insulating layer, etc.

[0394] The protective film can be made of a material that is impermeable to impurities such as water, and therefore can effectively prevent impurities such as water from diffusing from the outside to the inside.

[0395] The protective film may be made of an oxide, nitride, fluoride, sulfide, ternary compound, metal, polymer, or the like. For example, a material containing aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide, indium oxide, or the like; a material containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, gallium nitride, or the like; 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; or an oxide containing yttrium and zirconium.

[0396] The protective film is preferably formed using a film formation method that provides good step coverage. One such method is atomic layer deposition (ALD). It is preferable to use a material that can be formed using the ALD method for the protective film. By using the ALD method, it is possible to form a dense protective film with reduced defects such as cracks or pinholes, or with a uniform thickness. Furthermore, it is possible to reduce damage to the workpiece when forming the protective film.

[0397] For example, by forming a protective film using the ALD method, it is possible to form a uniform protective film with few defects on a surface having a complex uneven shape or on the top, side and back surfaces of a touch panel.

[0398] In the above manner, a light-emitting device manufactured using the light-emitting device described in any one of Embodiments 1 to 6 can be obtained.

[0399] The light-emitting device in this embodiment can have favorable characteristics because it uses the light-emitting device described in any one of Embodiments 1 to 6. Specifically, the light-emitting device described in any one of Embodiments 1 to 6 has favorable emission efficiency, and therefore can have low power consumption.

[0400] 7A shows an example of a full-color light-emitting device in which a light-emitting device that emits white light is formed and a colored layer (color filter) is provided, etc. 7A shows a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, and 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a driver circuit portion 1041, first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting device, a partition wall 1025, an EL layer 1028, a second electrode 1029 of the light-emitting device, a sealing substrate 1031, a sealant 1032, etc.

[0401] 7A , the colored layers (red colored layer 1034R, green colored layer 1034G, and blue colored layer 1034B) are provided on a transparent substrate 1033. A black matrix 1035 may also be provided. The transparent substrate 1033 on which the colored layers and black matrix are provided is aligned and fixed to the substrate 1001. The colored layers and black matrix 1035 are covered with an overcoat layer 1036. Also, in FIG. 7A , there are light-emitting layers from which light does not pass through the colored layers and exits to the outside, and light-emitting layers from which light passes through the colored layers of each color and exits to the outside. Light that does not pass through the colored layers is white, and light that passes through the colored layers is red, green, and blue, so that an image can be expressed using four color pixels.

[0402] 7B shows an example in which colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. In this manner, the colored layers may be provided between the substrate 1001 and the sealing substrate 1031.

[0403] Furthermore, the light-emitting device described above has a structure (bottom emission type) in which light is extracted from the substrate 1001 side on which the FET is formed, but a structure (top emission type) in which light is extracted from the sealing substrate 1031 side may also be used. A cross-sectional view of a top emission type light-emitting device is shown in FIG. 8 . In this case, a light-opaque substrate can be used as the substrate 1001. The process is the same as for a bottom emission type light-emitting device until a connection electrode connecting the FET and the anode of the light-emitting device is formed. Thereafter, a third interlayer insulating film 1037 is formed to cover the electrode 1022. This insulating film may also serve as a planarizing film. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film, as well as other known materials.

[0404] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting device are anodes here, but may be cathodes. In the case of a top-emission light-emitting device as shown in FIG. 8, the first electrodes are preferably reflective electrodes. The EL layer 1028 has a structure similar to that described as the unit 103 in any one of Embodiments 1 to 6, and has an element structure that can emit white light.

[0405] In the top-emission structure shown in FIG. 8 , sealing can be performed using a sealing substrate 1031 provided with colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B). A black matrix 1035 may be provided on the sealing substrate 1031 so as to be positioned between pixels. The colored layers (the red colored layer 1034R, the green colored layer 1034G, and the blue colored layer 1034B) or the black matrix may be covered with an overcoat layer 1036. Note that a light-transmitting substrate is used as the sealing substrate 1031. While an example of full-color display using four colors, red, green, blue, and white, is shown here, this is not particularly limited, and full-color display using four colors, red, yellow, green, and blue, or three colors, red, green, and blue, may also be performed.

[0406] A microcavity structure is suitable for use in top-emission light-emitting devices. A light-emitting device with a microcavity structure can be obtained by using a reflective electrode as the first electrode and a semi-transparent / semi-reflective electrode as the second electrode. At least an EL layer is provided between the reflective electrode and the semi-transparent / semi-reflective electrode, and at least a light-emitting layer that serves as a light-emitting region is provided.

[0407] The reflectance of the reflective electrode to visible light is 40% to 100%, preferably 70% to 100%, and the resistivity is 1×10 −２ The semi-transmitting and semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10 −２ It is assumed that the film has a resistivity of Ωcm or less.

[0408] Light emitted from the light-emitting layer included in the EL layer is reflected by the reflective electrode and the semi-transmissive and semi-reflective electrode, causing resonance.

[0409] In the light-emitting device, the optical distance between the reflective electrode and the semi-transmitting / semi-reflective electrode can be changed by changing the thickness of the transparent conductive film or the above-mentioned composite material, carrier transport material, etc. This makes it possible to intensify light of a resonant wavelength and attenuate light of a non-resonant wavelength between the reflective electrode and the semi-transmitting / semi-reflective electrode.

[0410] Note that, since the light reflected by the reflective electrode and returned (first reflected light) significantly interferes with the light (first incident light) that directly enters the semi-transmissive / semi-reflective electrode from the light-emitting layer, it is preferable to adjust the optical distance between the reflective electrode and the light-emitting layer to (2n-1)λ / 4 (where n is a natural number of 1 or more, and λ is the wavelength of the light emission to be amplified). By adjusting the optical distance, the phases of the first reflected light and the first incident light can be matched, thereby further amplifying the light emission from the light-emitting layer.

[0411] In the above configuration, the EL layer may have a structure having multiple light-emitting layers or a structure having a single light-emitting layer. For example, it may be combined with the above-mentioned tandem light-emitting device configuration, in which multiple EL layers are provided in one light-emitting device with a charge-generating layer sandwiched therebetween, and one or more light-emitting layers are formed in each EL layer.

[0412] The microcavity structure makes it possible to increase the light emission intensity of a specific wavelength in the front direction, thereby reducing power consumption. In the case of a light-emitting device that displays images using four sub-pixels of red, yellow, green, and blue, the yellow light emission has the effect of improving brightness, and the microcavity structure that matches the wavelength of each color can be applied to all sub-pixels, resulting in a light-emitting device with good characteristics.

[0413] The light-emitting device in this embodiment can have favorable characteristics because it uses the light-emitting device described in any one of Embodiments 1 to 6. Specifically, the light-emitting device described in any one of Embodiments 1 to 6 has favorable emission efficiency, and therefore can have low power consumption.

[0414] Up to this point, active matrix light-emitting devices have been described. From now on, passive matrix light-emitting devices will be described. FIG. 9 shows a passive matrix light-emitting device manufactured by applying the present invention. FIG. 9A is a perspective view showing the light-emitting device, and FIG. 9B is a cross-sectional view taken along X-Y line in FIG. 9A. In FIG. 9, an EL layer 955 is provided between an electrode 952 and an electrode 956 on a substrate 951. An end of the electrode 952 is covered with an insulating layer 953. A partition layer 954 is provided on the insulating layer 953. The sidewalls of the partition layer 954 are inclined such that the distance between one sidewall and the other sidewall becomes narrower as the sidewall approaches the substrate surface. That is, the cross section of the partition layer 954 in the short side direction is trapezoidal, and the bottom side (the side facing the same direction as the surface of the insulating layer 953 and in contact with the insulating layer 953) is shorter than the top side (the side facing the same direction as the surface of the insulating layer 953 and not in contact with the insulating layer 953). By providing the partition layer 954 in this manner, defects in the light-emitting device due to static electricity or the like can be prevented. Furthermore, a passive matrix light-emitting device using the light-emitting device described in any one of Embodiments 1 to 6 can be a highly reliable light-emitting device or a light-emitting device with low power consumption.

[0415] The light emitting device described above is capable of individually controlling a large number of minute light emitting devices arranged in a matrix, and is therefore suitable for use as a display device for displaying images.

[0416] This embodiment mode can be freely combined with other embodiment modes.

[0417] In this embodiment, an example in which the light-emitting device described in any one of Embodiments 1 to 6 is used as a lighting device will be described with reference to Fig. 10. Fig. 10B is a top view of the lighting device, and Fig. 10A is a cross-sectional view taken along the line e-f in Fig. 10B.

[0418] In the lighting device in this embodiment, a first electrode 401 is formed over a light-transmitting substrate 400 which serves as a support. The first electrode 401 corresponds to the electrode 101 in any one of Embodiments 1 to 6. When light is extracted from the first electrode 401 side, the first electrode 401 is formed using a light-transmitting material.

[0419] A pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400 .

[0420] An EL layer 403 is formed over the first electrode 401. The EL layer 403 corresponds to a structure in which the layer 104, the unit 103, and the layer 105 are combined, or a structure in which the layer 104, the unit 103, the intermediate layer 106, the unit 103(2), and the layer 105 are combined in any one of Embodiments 1 to 6. For details of these structures, see the relevant descriptions.

[0421] A second electrode 404 is formed to cover the EL layer 403. The second electrode 404 corresponds to the electrode 102 in any one of Embodiments 1 to 6. When light is extracted from the first electrode 401 side, the second electrode 404 is formed using a material with high reflectivity. The second electrode 404 is connected to a pad 412 to supply a voltage.

[0422] As described above, the lighting device described in this embodiment has a light-emitting device including the first electrode 401, the EL layer 403, and the second electrode 404. Since the light-emitting device has high emission efficiency, the lighting device in this embodiment can have low power consumption.

[0423] The lighting device is completed by bonding and sealing the substrate 400 on which the light-emitting device having the above structure is formed and the sealing substrate 407 using sealants 405 and 406. Either the sealant 405 or 406 may be used. Also, a desiccant may be mixed into the inner sealant 406 (not shown in FIG. 10B ), which can absorb moisture and improve reliability.

[0424] Furthermore, the pad 412 and a part of the first electrode 401 can be provided as an external input terminal by extending them outside the sealing materials 405 and 406. An IC chip 420 or the like on which a converter or the like is mounted may also be provided thereon.

[0425] As described above, the lighting device described in this embodiment uses the light-emitting device described in any one of Embodiments 1 to 6 as an EL element, and can be a lighting device with low power consumption.

[0426] Embodiment 11 In this embodiment, an example of an electronic device including the light-emitting device described in any one of Embodiments 1 to 6 as a part thereof will be described. The light-emitting device described in any one of Embodiments 1 to 6 has high emission efficiency and low power consumption. As a result, the electronic device described in this embodiment can be an electronic device having a light-emitting portion with low power consumption.

[0427] Examples of electronic devices to which the light-emitting devices are applied include television sets (also called televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game machines, personal digital assistants, sound reproducing devices, large game machines such as pachinko machines, etc. Specific examples of these electronic devices are shown below.

[0428] 11A illustrates an example of a television set. The television set has a display portion 7103 incorporated in a housing 7101. Here, the housing 7101 is supported by a stand 7105. Images can be displayed on the display portion 7103, and the display portion 7103 includes light-emitting devices described in any one of Embodiments 1 to 6 arranged in a matrix.

[0429] The television set can be operated using operation switches provided on the housing 7101 or a separate remote control 7110. Channels or volume can be controlled using operation keys 7109 provided on the remote control 7110, and images displayed on the display portion 7103 can be controlled. The remote control 7110 may be provided with a display portion 7107 that displays information output from the remote control 7110.

[0430] The television device is configured to include a receiver, a modem, etc. The receiver can receive general television broadcasts, and by connecting to a wired or wireless communication network via the modem, it is also possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0431] FIG. 11B shows a computer including a main body 7201, a housing 7202, a display portion 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, and the like. Note that this computer is manufactured by using the light-emitting devices described in any one of Embodiments 1 to 6 arranged in a matrix for the display portion 7203. The computer in FIG. 11B may have a configuration as shown in FIG. 11C. The computer in FIG. 11C is provided with a second display portion 7210 instead of the keyboard 7204 and the pointing device 7206. The second display portion 7210 is a touch panel type, and input can be performed by operating an input display displayed on the second display portion 7210 with a finger or a dedicated pen. The second display portion 7210 can display not only an input display but also other images. The display portion 7203 may also be a touch panel. The two screens are connected by a hinge, which can prevent problems such as scratches or breakage of the screens during storage or transportation.

[0432] 11D illustrates an example of a mobile terminal. The mobile terminal includes a display portion 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile terminal includes the display portion 7402 in which the light-emitting devices described in any one of Embodiments 1 to 6 are arranged in a matrix.

[0433] 11D can be configured so that information can be input by touching the display portion 7402 with a finger or the like. In this case, operations such as making a call or creating an email can be performed by touching the display portion 7402 with a finger or the like.

[0434] The screen of the display portion 7402 has three main modes. The first is a display mode mainly for displaying images, the second is an input mode mainly for inputting information such as characters, and the third is a display+input mode that combines the display mode and the input mode.

[0435] For example, when making a call or creating an email, the display portion 7402 may be set to a character input mode mainly for inputting characters, and characters displayed on the screen may be input. In this case, it is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402.

[0436] In addition, by providing a detection device having a sensor that detects tilt, such as a gyro sensor or an acceleration sensor, inside the mobile terminal, the orientation of the mobile terminal (portrait or landscape) can be determined and the screen display of the display portion 7402 can be automatically switched.

[0437] The screen mode can be switched by touching the display portion 7402 or by operating the operation buttons 7403 on the housing 7401. The screen mode can also be switched depending on the type of image displayed on the display portion 7402. For example, if the image signal to be displayed on the display portion is moving image data, the display mode is selected, and if it is text data, the input mode is selected.

[0438] In addition, in the input mode, a signal detected by an optical sensor in the display portion 7402 may be detected, and if there is no input by touch operation on the display portion 7402 for a certain period of time, the screen mode may be controlled to switch from the input mode to the display mode.

[0439] The display portion 7402 can also function as an image sensor. For example, personal authentication can be performed by touching the display portion 7402 with a palm or a finger to capture an image of a palm print, a fingerprint, or the like. Furthermore, by using a backlight that emits near-infrared light or a sensing light source that emits near-infrared light for the display portion, finger veins, palm veins, or the like can also be captured.

[0440] FIG. 12A is a schematic diagram showing an example of a cleaning robot.

[0441] The cleaning robot 5100 has a display 5101 arranged on its top surface, multiple cameras 5102 arranged on its side, a brush 5103, and an operation button 5104. Although not shown, the cleaning robot 5100 is also provided with tires, a suction port, and the like on its bottom surface. The cleaning robot 5100 is also provided with various other sensors, such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezoelectric sensor, an optical sensor, and a gyro sensor. The cleaning robot 5100 is also provided with wireless communication means.

[0442] The cleaning robot 5100 can move by itself, detect dust 5120, and suck up the dust from a suction port provided on the bottom surface.

[0443] The cleaning robot 5100 can also analyze the image captured by the camera 5102 to determine whether there are any obstacles such as walls, furniture, or steps. If the image analysis detects an object that may become tangled in the brush 5103, such as a wire, the cleaning robot 5100 can stop the rotation of the brush 5103.

[0444] The display 5101 can display the remaining battery level, the amount of dust that has been sucked up, etc. The path traveled by the cleaning robot 5100 may be displayed on the display 5101. The display 5101 may also be a touch panel, and an operation button 5104 may be provided on the display 5101.

[0445] The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. Images captured by the camera 5102 can be displayed on the portable electronic device 5140. This allows the owner of the cleaning robot 5100 to know the state of the room even when they are away from home. In addition, the display on the display 5101 can be confirmed on the portable electronic device 5140 such as a smartphone.

[0446] The light-emitting device of one embodiment of the present invention can be used for the display 5101 .

[0447] The robot 2100 shown in FIG. 12B includes a computing device 2110, an illuminance sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0448] The microphone 2102 has a function of detecting the user's voice, environmental sounds, etc. The speaker 2104 has a function of emitting sound. The robot 2100 can communicate with the user using the microphone 2102 and the speaker 2104.

[0449] The display 2105 has a function of displaying various information. The robot 2100 can display information desired by the user on the display 2105. The display 2105 may be equipped with a touch panel. The display 2105 may also be a detachable information terminal, which can be installed in a fixed position on the robot 2100 to enable charging and data transfer.

[0450] The upper camera 2103 and the lower camera 2106 have a function of capturing images of the surroundings of the robot 2100. In addition, the obstacle sensor 2107 can detect the presence or absence of an obstacle in the moving direction when the robot 2100 moves forward using the moving mechanism 2108. The robot 2100 can recognize the surrounding environment and move safely using the upper camera 2103, the lower camera 2106, and the obstacle sensor 2107. The light-emitting device of one embodiment of the present invention can be used for the display 2105.

[0451] 12C is a diagram showing an example of a goggle-type display. The goggle-type display includes, for example, a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004, operation keys (including a power switch or an operation switch), a connection terminal 5006, a sensor 5007 (having a function of measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared light), a microphone 5008, a display unit 5002, a support unit 5012, and earphones 5013.

[0452] The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the display portion 5002 .

[0453] 13 shows an example in which the light-emitting device described in any one of Embodiments 1 to 6 is used in a desk lamp, which is a lighting device. The desk lamp shown in FIG. 13 includes a housing 2001 and a light source 2002, and the lighting device described in Embodiment 10 may be used as the light source 2002.

[0454] 14 shows an example in which the light-emitting device described in any one of Embodiments 1 to 6 is used as an indoor lighting device 3001. Since the light-emitting device described in any one of Embodiments 1 to 6 has high emission efficiency, the lighting device can have low power consumption. Furthermore, since the light-emitting device described in any one of Embodiments 1 to 6 can be made large, it can be used as a large-area lighting device. Furthermore, since the light-emitting device described in any one of Embodiments 1 to 6 is thin, it can be used as a thin lighting device.

[0455] The light-emitting device described in any one of Embodiments 1 to 6 can also be mounted on a windshield or a dashboard of an automobile. Figure 15 shows one mode in which the light-emitting device described in any one of Embodiments 1 to 6 is used on a windshield or a dashboard of an automobile. Display regions 5200 to 5203 are display regions provided using the light-emitting device described in any one of Embodiments 1 to 6.

[0456] The display region 5200 and the display region 5201 are display devices provided on the windshield of an automobile, and are equipped with the light-emitting device described in any one of Embodiments 1 to 6. The light-emitting device described in any one of Embodiments 1 to 6 can be a so-called see-through display device, in which the opposite side can be seen through, by forming the first electrode and the second electrode using light-transmitting electrodes. A see-through display can be installed on the windshield of an automobile without obstructing the view. When a transistor or the like for driving is provided, a light-transmitting transistor such as an organic transistor made of an organic semiconductor material or a transistor using an oxide semiconductor is preferably used.

[0457] The display area 5202 is a display device provided in a pillar portion and equipped with the light-emitting device described in any one of Embodiments 1 to 6. By displaying an image from an imaging means provided in the vehicle body in the display area 5202, the view blocked by the pillar can be complemented. Similarly, the display area 5203 provided in the dashboard portion can complement the view blocked by the vehicle body by displaying an image from an imaging means provided outside the vehicle, thereby compensating for blind spots and improving safety. By displaying an image to complement the invisible part, safety can be confirmed more naturally and without discomfort.

[0458] The display area 5203 can provide various information by displaying navigation information, speed or revolutions, mileage, remaining fuel, gear status, air conditioning settings, etc. The display items or layout can be changed as appropriate to suit the user's preferences. Note that this information can also be provided in the display areas 5200 to 5202. The display areas 5200 to 5203 can also be used as lighting devices.

[0459] 16A to 16C show a foldable portable information terminal 9310. Fig. 16A shows the portable information terminal 9310 in an unfolded state. Fig. 16B shows the portable information terminal 9310 in a state in the process of changing from one of the unfolded state and the folded state to the other. Fig. 16C shows the portable information terminal 9310 in a folded state. The portable information terminal 9310 has excellent portability in a folded state, and has excellent display visibility due to a seamless, wide display area in an unfolded state.

[0460] The display panel 9311 is supported by three housings 9315 connected by hinges 9313. Note that the display panel 9311 may be a touch panel (input / output device) equipped with a touch sensor (input device). Furthermore, the display panel 9311 can be reversibly transformed from an unfolded state to a folded state by bending the two housings 9315 via the hinges 9313. The light-emitting device of one embodiment of the present invention can be used for the display panel 9311.

[0461] Note that the structure described in this embodiment mode can be used by appropriately combining the structures described in any of Embodiment Modes 1 to 6.

[0462] As described above, the light-emitting device including the light-emitting device described in any one of Embodiments 1 to 6 has a very wide range of application, and the light-emitting device can be applied to electronic devices in a variety of fields. By using the light-emitting device described in any one of Embodiments 1 to 6, electronic devices with low power consumption can be obtained.

[0463] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0464] In this example, a light-emitting device 222 (22) of one embodiment of the present invention will be described with reference to FIGS. 17 to 45 . Note that in the figures and tables of this example, subscripts and superscripts are written in standard size for convenience. For example, subscripts used for abbreviations and superscripts used for units are written in standard size in the tables. The descriptions in these tables can be interpreted with reference to the description in the specification.

[0465] 17A to 17C are diagrams illustrating the configuration of the light-emitting device 150. FIG.

[0466] FIG. 18 shows the absorption spectrum of TTPA, Ir(5tBuppy) ３ 1 is a diagram illustrating the emission spectrum of TTPA.

[0467] FIG. 19 shows the absorption spectrum of TTPA, Ir(4tBuppy) ３ 1 is a diagram illustrating the emission spectrum of TTPA.

[0468] FIG. 20 shows the absorption spectrum of 2Ph-mmtBuDPhA2Anth, Ir(5tBuppy) ３ 1 is a diagram illustrating the emission spectrum of 2Ph-mmtBuDPhA2Anth.

[0469] FIG. 21 shows the absorption spectrum of 2Ph-mmtBuDPhA2Anth, Ir(4tBuppy) ３ 1 is a diagram illustrating the emission spectrum of 2Ph-mmtBuDPhA2Anth.

[0470] FIG. 22 is a diagram illustrating the current density-luminance characteristics of the light-emitting device 222 (22).

[0471] FIG. 23 is a diagram illustrating the luminance-current efficiency characteristics of the light-emitting device 222 (22).

[0472] FIG. 24 is a diagram illustrating the voltage-luminance characteristics of the light-emitting device 222 (22).

[0473] FIG. 25 is a diagram illustrating the voltage-current characteristics of the light-emitting device 222 (22).

[0474] 26 is a diagram illustrating the luminance-external quantum efficiency characteristics of the light-emitting device 222 (22). The external quantum efficiency was calculated from the luminance, assuming that the light distribution characteristics of the light-emitting device are Lambertian.

[0475] FIG. 27 shows the light emitting device 222 (22) at 1000 cd / m ２ 10 is a diagram illustrating an emission spectrum when light is emitted at a luminance of 1000 .mu.m.

[0476] FIG. 28 shows the current density at 50 mA / cm ２ 10 is a diagram illustrating the normalized luminance vs. time change characteristics when the light-emitting device 222 (22) is caused to emit light at a constant current density of 1000 .mu.m.

[0477] FIG. 29 is a diagram illustrating the voltage-current characteristics of the reference device.

[0478] FIG. 30 shows the reference device at 2.5 mA / cm ２ 10 is a diagram illustrating an emission spectrum when light is emitted at a current density of 1000 .mu.m.

[0479] Figure 31 shows the 1300 cd / m ２ 10 is a graph showing a change in the light emission intensity of a light emitting device pulse-driven at a voltage corresponding to the condition shown in FIG.

[0480] <Light-Emitting Device 222 (22)> The light-emitting device 222 (22) fabricated and described in this example has a configuration similar to that of the light-emitting device 150 (see FIG. 17A).

[0481] The light-emitting device 150 includes an electrode 101, an electrode 102, and a layer 111 (see FIG. 17A). The electrode 102 has an area that overlaps with the electrode 101, and the layer 111 is located between the electrode 101 and the electrode 102.

[0482] Layer 111 includes a light-emitting material FM, an energy donor material ED, and a host material.

[0483] The light-emitting material FM has a function of emitting fluorescence, and the light-emitting material FM has an end point at a wavelength λ abs (nm) that is located at the longest wavelength of the absorption spectrum Abs (see FIG. 17C).

[0484] An organometallic complex is used as the energy donor material ED, and the organometallic complex has a ligand, and the ligand has a substituent R １ and the substituent R １ is either an alkyl group, a cycloalkyl group, or a trialkylsilyl group. The alkyl group has 3 to 12 carbon atoms, the cycloalkyl group has 3 to 10 carbon atoms forming a ring, and the trialkylsilyl group has 3 to 12 carbon atoms.

[0485] The organometallic complex also has the function of emitting phosphorescence at room temperature, and the phosphorescence has an end point at wavelength λp (nm) located at the shortest wavelength of the spectrum, and the wavelength λp is located at a wavelength shorter than the wavelength λabs.

[0486] In addition, the organometallic complex has a first HOMO level HOMO1 and a first LUMO level LUMO1 (see FIG. 17B).

[0487] The host material has a function of emitting delayed fluorescence at room temperature, and the host material has a second HOMO level HOMO2 and a second LUMO level LUMO2.

[0488] The first HOMO level HOMO1, the first LUMO level LUMO1, the second HOMO level HOMO2, and the second LUMO level LUMO2 satisfy the following formula (1).

[0489]

[0490] <<Configuration of Light-Emitting Device 222 (22)>> The configuration of the light-emitting device 222 (22) is shown in Table 1. The structural formulas, HOMO levels, and LUMO levels of the materials used in the light-emitting device described in this example are shown below.

[0491] The luminescent material FM of the light-emitting device 222 (22) has an absorption spectrum with the longest wavelength end at a wavelength of 519 nm (see FIG. 20). The absorption spectrum of a toluene solution of the luminescent material FM was measured at room temperature using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation).

[0492] Ir(5tBuppy) used in organometallic complex of light-emitting device 222 (22) ３has the function of emitting phosphorescence. The phosphorescence has an end point at the shortest wavelength of the spectrum at a wavelength of 484 nm, and the end point is located at a wavelength shorter than 519 nm. ３ has a first HOMO level HOMO1 at -5.32 eV and a first LUMO level LUMO1 at -2.25 eV. The phosphorescence spectrum of a dichloromethane solution of the organometallic complex was measured at room temperature using a fluorometer (FP-8600 model, manufactured by JASCO Corporation). The HOMO level and LUMO level of the organometallic complex were calculated from the oxidation potential and reduction potential obtained by cyclic voltammetry (CV) measurement using an electrochemical analyzer (manufactured by BAS Inc., model number: ALS Model 600A or 600C).

[0493] The material used as the host material of the light-emitting device 222 (22) has the function of emitting delayed fluorescence. Specifically, mPCCzPTzn-02 emits delayed fluorescence. This material also has a second HOMO level HOMO2 at -5.69 eV and a second LUMO level LUMO2 at -3.00 eV (see Table 2). The HOMO level and LUMO level of the host material were calculated from the oxidation potential and reduction potential obtained by cyclic voltammetry (CV) measurement using an electrochemical analyzer (manufactured by BAS Inc., model number: ALS Model 600A or 600C).

[0494] The value of (LUMO2-HOMO2) is 2.69 eV, which is smaller than the value of (LUMO1-HOMO1), 3.07 eV.

[0495]

[0496]

[0497]

[0498]

[0499]

[0500] <<Method of Fabricating Light-Emitting Device 222 (22)>> The light-emitting device 222 (22) described in this example was fabricated using a method having the following steps.

[0501] [First Step] In the first step, the electrode 101 was formed. Specifically, the electrode 101 was formed by a sputtering method using indium oxide-tin oxide (abbreviation: ITSO) containing silicon or silicon oxide as a target.

[0502] The electrode 101 includes ITSO, has a thickness of 70 nm, and is 4 mm ２ It has an area of ​​(2 mm x 2 mm).

[0503] Next, the substrate on which the electrode 101 was formed was washed with water, baked at 200° C. for 1 hour, and then subjected to UV ozone treatment for 370 seconds. −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and vacuum baking was performed at 170° C. for 30 minutes in a heating chamber of the vacuum deposition apparatus. Thereafter, the substrate was allowed to cool for about 30 minutes.

[0504] [Second Step] In the second step, the layer 104 was formed on the electrode 101. Specifically, materials were co-evaporated using a resistance heating method.

[0505] The layer 104 is made of 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) and molybdenum(VI) oxide (abbreviation: MoO ３ ) to DBT3P-II:MoO ３ = 1:0.5 (weight ratio) and had a thickness of 40 nm.

[0506] [Third Step] In the third step, a layer 112 was formed on the layer 104. Specifically, a material was evaporated by using a resistance heating method.

[0507] The layer 112 contains 9-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]-9H-carbazole (abbreviation: mCzFLP) and has a thickness of 20 nm.

[0508] [Fourth Step] In the fourth step, the layer 111 was formed over the layer 112. Specifically, materials were co-evaporated by using a resistance heating method.

[0509] The layer 111 is made of 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9′-phenyl-2,3′-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), tris[2-[5-(tert-butyl)-2-pyridinyl-κN]phenyl-κC]iridium (abbreviation: Ir(5tBuppy) ３ ) and N,N'-bis(3,5-di-tert-butylphenyl)-N,N'-bis[3,5-bis(3,5-di-tert-butylphenyl)phenyl]-2-phenylanthracene-9,10-diamine (abbreviation: 2Ph-mmtBuDPhA2Anth) were used in mPCCzPTzn-02:Ir(5tBuppy) ３ The mPCCzPTzn-02 film contained mPCCzPTzn-02 in a weight ratio of 1:0.1:0.05 and had a thickness of 40 nm. Note that mPCCzPTzn-02 is a substance that exhibits thermally activated delayed fluorescence.

[0510]

[0511] [Fifth Step] In the fifth step, a layer 113A was formed on the layer 111. Specifically, a material was evaporated by using a resistance heating method.

[0512] The layer 113A contains 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and has a thickness of 20 nm.

[0513] [Sixth Step] In the sixth step, the layer 113B was formed on the layer 113A. Specifically, the material was evaporated by using a resistance heating method.

[0514] The layer 113B contains 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB) and has a thickness of 10 nm.

[0515] [Seventh Step] In the seventh step, the layer 105 was formed on the layer 113B. Specifically, the material was evaporated by using a resistance heating method.

[0516] The layer 105 contains lithium fluoride (abbreviated as LiF) and has a thickness of 1 nm.

[0517] [Eighth Step] In the eighth step, the electrode 102 was formed on the layer 105. Specifically, a material was evaporated by using a resistance heating method.

[0518] The electrode 102 contains aluminum (abbreviated as Al) and has a thickness of 200 nm.

[0519] <<Operation Characteristics of Light-Emitting Device 222 (22)>> When power was supplied, the light-emitting device 222 (22) emitted green light EL1 (see FIG. 17A). The operation characteristics of the light-emitting device 222 (22) were measured (see FIGS. 22 to 27). The luminance, CIE chromaticity, and emission spectrum were measured at room temperature using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0520] The fabricated light-emitting device had a brightness of 1000 cd / m ２ The main initial characteristics when the light-emitting device was driven to emit light at a constant current density (50 mA / cm ２ ) and the LT90, which is the time elapsed until the luminance decreased to 90% of the initial luminance, is shown in Table 4. Table 4 also shows the properties of other light-emitting devices whose configurations will be described later.

[0521]

[0522] The light-emitting device 222 (22) was found to exhibit good characteristics. For example, the light-emitting device 222 (22) emitted light with an emission spectrum originating from the light-emitting material FM, with a peak wavelength at approximately 540 nm (see FIG. 27). Furthermore, no light emission originating from the energy donor material ED was observed. Alternatively, energy was transferred from the energy donor material ED to the light-emitting material FM. Furthermore, undesired energy transfer from the energy donor material ED to the light-emitting material FM was suppressed. Furthermore, energy transfer from the energy donor material ED to the light-emitting material FM due to the Dexter mechanism was suppressed.

[0523] Furthermore, the light-emitting device 222 (22) achieved 1000 cd / m at a lower voltage than the comparative device 022 (22) and the comparative device 021 (22). ２ (See Table 4.) Furthermore, the device exhibited a higher external quantum efficiency than the comparative device 022 (22). Furthermore, the device exhibited a higher external quantum efficiency than the comparative device 021 (22).

[0524] Also, 50 mA / cm ２ When light was emitted at a constant current density of 1000 kJ / s, the light-emitting device 222(22) took a longer time for the luminance to decrease to 90% of the initial luminance than the comparative device 022(22).

[0525] Reference Example 1 A comparative device 022(22) prepared and described in this Reference Example differs from light-emitting device 222(22) in that 3,3'-9H-carbazol-9-yl-biphenyl (abbreviation: mCBP) was used as the host material instead of mPCCzPTzn-02. Furthermore, a comparative device 021(22) prepared and described in this Reference Example differs from light-emitting device 222(22) in that mCBP was used as the host material instead of mPCCzPTzn-02 and that N,N,N',N'-tetrakis(4-methylphenyl)-9,10-anthracenediamine (abbreviation: TTPA) was used as the light-emitting material FM instead of 2Ph-mmtBuDPhA2Anth.

[0526] <Configuration of Comparative Device 022(22)> The configuration of the comparative device 022(22) fabricated in this reference example is shown in Table 5. Note that the comparative device 022(22) differs from the light-emitting device 222(22) in that mCBP was used as the host material.

[0527] The mCBP used as the host material in the light-emitting device 022(22) does not emit delayed fluorescence. This material has a second HOMO level HOMO2 at -5.93 eV and a second LUMO level LUMO2 at -2.22 eV (see Table 2). The HOMO and LUMO levels of the host material were calculated from the oxidation and reduction potentials obtained by cyclic voltammetry (CV) measurements using an electrochemical analyzer (manufactured by BAS Inc., model number: ALS Model 600A or 600C).

[0528] The value of (LUMO2-HOMO2) is 3.71 eV, which is larger than the value of (LUMO1-HOMO1) of 3.07 eV.

[0529]

[0530]

[0531] <<Method of Fabricating Comparative Device 022 (22)>> The light-emitting device 022 (22) described in this example was fabricated using a method having the following steps.

[0532] The method for fabricating light-emitting device 022(22) differs from the method for fabricating light-emitting device 222(22) in that mCBP was used as the host material instead of mPCCzPTzn-02 in the step of forming layer 111. Here, the differences will be described in detail, and the above description will be used for the parts where similar methods were used.

[0533] [Fourth Step] In the fourth step, the layer 111 was formed over the layer 112. Specifically, materials were co-evaporated by using a resistance heating method.

[0534] The layer 111 is made of mCBP, Ir(5tBuppy) ３ and 2Ph-mmtBuDPhA2Anth to mCBP:Ir(5tBuppy) ３ :2Ph-mmtBuDPhA2Anth=1:0.1:0.05 (weight ratio) and had a thickness of 40 nm (see Table 3).

[0535] <Configuration of Comparative Device 021 (22)> The comparative device 021 (22) prepared in this reference example differs from the light-emitting device 222 (22) in that mCBP was used as the host material and that TTPA was used as the light-emitting material FM instead of 2Ph-mmtBuDPhA2Anth.

[0536] The host material mCBP in the light-emitting device 022(22) does not emit delayed fluorescence and has a second HOMO level HOMO2 at −5.93 eV and a second LUMO level LUMO2 at −2.22 eV (see Table 2).

[0537] The value of (LUMO2-HOMO2) is 3.71 eV, which is larger than the value of (LUMO1-HOMO1) of 3.07 eV.

[0538] In addition, TTPA used as the light-emitting material FM of the light-emitting device 021 (22) has a second substituent R ２ The second substituent R ２ is a methyl group.

[0539] <<Method of Fabricating Comparative Device 021 (22)>> The light-emitting device 021 (22) described in this example was fabricated using a method having the following steps.

[0540] The method for fabricating light-emitting device 021 (22) differs from the method for fabricating light-emitting device 222 (22) in that mCBP was used as the host material instead of mPCCzPTzn-02 and that TTPA was used as the light-emitting material FM instead of 2Ph-mmtBuDPhA2Anth in the step of forming layer 111. Here, the differences will be described in detail, and the above description will be used for the parts in which similar methods were used.

[0541] [Fourth Step] In the fourth step, the layer 111 was formed over the layer 112. Specifically, materials were co-evaporated by using a resistance heating method.

[0542] The layer 111 is made of mCBP, Ir(5tBuppy) ３ and TTPA to mCBP:Ir(5tBuppy) ３ :TTPA=1:0.1:0.05 (weight ratio) and had a thickness of 40 nm (see Table 3).

[0543] Reference Example 2 The reference device 1 fabricated and described in this reference example has a configuration similar to that of the light-emitting device 150 (see FIG. 17A).

[0544] The light-emitting device 150 includes an electrode 101, an electrode 102, and a layer 111. The electrode 102 has an area that overlaps with the electrode 101, and the layer 111 is located between the electrode 101 and the electrode 102. The light-emitting device 150 also includes a layer 104 and a layer 105.

[0545] The layer 111 contains a host material, and the host material has the function of emitting delayed fluorescence at room temperature.

[0546] <<Configuration of Reference Device 1>> The configuration of Reference Device 1 is shown in Table 6. The structural formulas of the materials used in the Reference Device described in this example are shown below.

[0547]

[0548] <<Method for Producing Reference Device 1>> Reference device 1 described in this example was produced using a method including the following steps.

[0549] [First Step] In the first step, the electrode 101 was formed. Specifically, the electrode 101 was formed by a sputtering method using indium oxide-tin oxide (abbreviation: ITSO) containing silicon or silicon oxide as a target.

[0550] The electrode 101 includes ITSO, has a thickness of 70 nm, and is 4 mm ２ It has an area of ​​(2 mm x 2 mm).

[0551] Next, the substrate on which the electrode 101 was formed was washed with water, baked at 200° C. for 1 hour, and then subjected to UV ozone treatment for 370 seconds. −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and vacuum baking was performed at 170° C. for 30 minutes in a heating chamber of the vacuum deposition apparatus. Thereafter, the substrate was allowed to cool for about 30 minutes.

[0552] [Second Step] In the second step, a layer 104 was formed on the electrode 101. Specifically, materials were co-evaporated using a resistance heating method.

[0553] The layer 104 is made of DBT3P-II and MoO ３ DBT3P-II:MoO ３ = 1:0.5 (weight ratio) and had a thickness of 30 nm.

[0554] [Third Step] In the third step, a layer 112 was formed on the layer 104. Specifically, a material was evaporated by using a resistance heating method.

[0555] The layer 112 contains 3,3′-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP) and has a thickness of 20 nm.

[0556] [Fourth Step] In the fourth step, the layer 111 was formed on the layer 112. Specifically, the material was evaporated by using a resistance heating method.

[0557] The layer 111 contains mPCCzPTzn-02 and has a thickness of 30 nm.

[0558] [Fifth Step] In the fifth step, a layer 113A was formed on the layer 111. Specifically, a material was evaporated by using a resistance heating method.

[0559] Note that layer 113A contains mPCCzPTzn-02 and has a thickness of 20 nm.

[0560] [Sixth Step] In the sixth step, the layer 113B was formed on the layer 113A. Specifically, the material was evaporated by using a resistance heating method.

[0561] The layer 113B contains 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) and has a thickness of 10 nm.

[0562] [Seventh Step] In the seventh step, the layer 105 was formed on the layer 113B. Specifically, the material was evaporated by using a resistance heating method.

[0563] The layer 105 contains LiF and has a thickness of 1 nm.

[0564] [Eighth Step] In the eighth step, the electrode 102 was formed on the layer 105. Specifically, a material was evaporated using a resistance heating method.

[0565] The electrode 102 contains Al and has a thickness of 200 nm.

[0566] <<Operating Characteristics of Reference Device 1>> When power was supplied, Reference Device 1 emitted light EL1 (see FIG. 17A). The operating characteristics of Reference Device 1 were measured (see FIGS. 29 and 30). Note that a color luminance meter (Topcon Corporation, BM-5A) was used to measure the luminance and CIE chromaticity, and a multichannel spectrometer (Hamamatsu Photonics KK, PMA-11) was used to measure the emission spectrum, all at room temperature.

[0567] In addition, delayed fluorescence was measured using a picosecond fluorescence lifetime system (manufactured by Hamamatsu Photonics). ２ A voltage corresponding to the conditions shown in was applied to Reference Device 1, a predetermined voltage was maintained in a rectangular pulse form for 100 μs, and the decay of delayed fluorescence was observed for 20 μs. A negative bias of −5 V was also applied during the period in which the decay of delayed fluorescence was observed. Measurements were repeated at a cycle of 10 Hz, and the data was integrated. The luminescence intensity of Reference Device 1 pulse-driven at a predetermined voltage is shown in FIG.

[0568] Holes supplied from the electrode 101 and electrons supplied from the electrode 102 recombined in the layer 111, and light was emitted from the excited host material, specifically, mPCCzPTzn-02 (see FIG. 30). Light emission from excitons with a short lifetime of 0.3 μs or less and light emission from excitons with a long lifetime of 6 μs were confirmed (see FIG. 31). This confirmed that singlet excitons were generated via triplet excitons with a long lifetime.

[0569] In this example, light-emitting devices 321(22) to 332(22) of one embodiment of the present invention will be described with reference to FIG. 17 and FIGS. 32 to 38 . Note that in the figures and tables of this example, subscripts and superscripts are written in standard size for convenience. For example, subscripts used for abbreviations and superscripts used for units are written in standard size in the tables. The descriptions in these tables can be interpreted with reference to the description in the specification.

[0570] FIG. 32 is a diagram illustrating the current density-luminance characteristics of the light-emitting device 321(22) and the light-emitting device 331(22).

[0571] FIG. 33 is a diagram illustrating the luminance-current efficiency characteristics of the light-emitting device 321(22) and the light-emitting device 331(22).

[0572] FIG. 34 is a diagram illustrating the voltage-luminance characteristics of the light-emitting device 321(22) and the light-emitting device 331(22).

[0573] FIG. 35 is a diagram illustrating the voltage-current characteristics of the light-emitting device 321(22) and the light-emitting device 331(22).

[0574] 36 is a diagram illustrating the luminance-external quantum efficiency characteristics of the light-emitting device 321(22) and the light-emitting device 331(22). The external quantum efficiency was calculated from the luminance, assuming that the light distribution characteristics of the light-emitting device are Lambertian.

[0575] FIG. 37 shows the light emitting device 321(22) and the light emitting device 331(22) at 1000 cd / m ２ 10 is a diagram illustrating an emission spectrum when light is emitted at a luminance of 1000 .mu.m.

[0576] FIG. 38 shows the current density at 50 mA / cm ２ 10 is a diagram illustrating the normalized luminance-time change characteristics when the light-emitting device 321(22) and the light-emitting device 331(22) are caused to emit light at a constant current density of 1000 .mu.m.

[0577] <Light-Emitting Device 321 (22)> The light-emitting device 321 (22) fabricated and described in this example has the same configuration as the light-emitting device 150 (see FIG. 17A).

[0578] The light-emitting device 150 includes an electrode 101, an electrode 102, and a layer 111 (see FIG. 17A). The electrode 102 has an area that overlaps with the electrode 101, and the layer 111 is located between the electrode 101 and the electrode 102.

[0579] Layer 111 includes a light-emitting material FM, an energy donor material ED, and a host material.

[0580] The light-emitting material FM has a function of emitting fluorescence, and the light-emitting material FM has an end point at a wavelength λ abs (nm) that is located at the longest wavelength of the absorption spectrum Abs (see FIG. 17C).

[0581] An organometallic complex is used as the energy donor material ED, and the organometallic complex has a ligand, and the ligand has a substituent R １ and the substituent R １ is either an alkyl group, a cycloalkyl group, or a trialkylsilyl group. The alkyl group has 3 to 12 carbon atoms, the cycloalkyl group has 3 to 10 carbon atoms forming a ring, and the trialkylsilyl group has 3 to 12 carbon atoms.

[0582] The organometallic complex also has the function of emitting phosphorescence at room temperature, and the phosphorescence has an end point at wavelength λp (nm) located at the shortest wavelength of the spectrum, and the wavelength λp is located at a wavelength shorter than the wavelength λabs.

[0583] In addition, the organometallic complex has a first HOMO level HOMO1 and a first LUMO level LUMO1 (see FIG. 17B).

[0584] The host material has a function of emitting delayed fluorescence at room temperature, and the host material has a second HOMO level HOMO2 and a second LUMO level LUMO2.

[0585] The first HOMO level HOMO1, the first LUMO level LUMO1, the second HOMO level HOMO2, and the second LUMO level LUMO2 satisfy the following formula (1).

[0586]

[0587] <<Configuration of Light-Emitting Device 321 (22)>> The configuration of the light-emitting device 321 (22) is shown in Table 7. The structural formulas, HOMO levels, and LUMO levels of the materials used in the light-emitting device described in this example are shown below.

[0588] The TTPA used as the luminescent material FM in the light-emitting device 321(22) has an absorption spectrum with the longest wavelength at 514 nm (see FIG. 18). The absorption spectrum of a toluene solution of the luminescent material FM was measured at room temperature using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation).

[0589] Ir(5tBuppy) used in the organometallic complex of light-emitting device 321 (22) ３ has the function of emitting phosphorescence. The phosphorescence has an end point at the shortest wavelength of the spectrum at a wavelength of 484 nm, and the end point is located at a wavelength shorter than 514 nm. ３ has a first HOMO level HOMO1 at -5.32 eV and a first LUMO level LUMO1 at -2.25 eV. The phosphorescence spectrum of a dichloromethane solution of the organometallic complex was measured at room temperature using a fluorometer (FP-8600 model, manufactured by JASCO Corporation). The HOMO level and LUMO level of the organometallic complex were calculated from the oxidation potential and reduction potential obtained by cyclic voltammetry (CV) measurement using an electrochemical analyzer (manufactured by BAS Inc., model number: ALS Model 600A or 600C).

[0590] The mixed material used as the host material of light-emitting device 321 (22) has the function of emitting delayed fluorescence. Specifically, the mixed material containing mPCCzPTzn-02 and PCCP emits delayed fluorescence. Furthermore, the mixed material has a second HOMO level HOMO2 at -5.63 eV and a second LUMO level LUMO2 at -3.00 eV (see Table 2). The HOMO level and LUMO level of the host material were calculated from the oxidation potential and reduction potential obtained by cyclic voltammetry (CV) measurement using an electrochemical analyzer (manufactured by BAS Inc., model number: ALS Model 600A or 600C).

[0591] The value of (LUMO2-HOMO2) is 2.63 eV, which is smaller than the value of (LUMO1-HOMO1), 3.07 eV.

[0592]

[0593] <<Method of Fabricating Light-Emitting Device 321 (22)>> The light-emitting device 321 (22) described in this example was fabricated using a method having the following steps.

[0594] [First Step] In the first step, the electrode 101 was formed. Specifically, the electrode 101 was formed by a sputtering method using indium oxide-tin oxide (abbreviation: ITSO) containing silicon or silicon oxide as a target.

[0595] The electrode 101 includes ITSO, has a thickness of 70 nm, and is 4 mm ２ It has an area of ​​(2 mm x 2 mm).

[0596] Next, the substrate on which the electrode 101 was formed was washed with water, baked at 200° C. for 1 hour, and then subjected to UV ozone treatment for 370 seconds. −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and vacuum baking was performed at 170° C. for 30 minutes in a heating chamber of the vacuum deposition apparatus. Thereafter, the substrate was allowed to cool for about 30 minutes.

[0597] [Second Step] In the second step, the layer 104 was formed on the electrode 101. Specifically, materials were co-evaporated using a resistance heating method.

[0598] The layer 104 is made of DBT3P-II and MoO ３ DBT3P-II:MoO ３ = 1:0.5 (weight ratio) and had a thickness of 40 nm.

[0599] [Third Step] In the third step, a layer 112 was formed on the layer 104. Specifically, a material was evaporated by using a resistance heating method.

[0600] The layer 112 contains 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP) and has a thickness of 20 nm.

[0601] [Fourth Step] In the fourth step, the layer 111 was formed over the layer 112. Specifically, materials were co-evaporated by using a resistance heating method.

[0602] The layer 111 is made of mPCCzPTzn-02, PCCP, Ir (5tBuppy) ３ and TTPA to mPCCzPTzn-02:PCCP:Ir(5tBuppy) ３ The film contained mPCCzPTzn-02 and PCCP in a weight ratio of 0.5:0.5:0.1:0.05, and had a thickness of 40 nm. Note that mPCCzPTzn-02 and PCCP are substances that form an exciplex.

[0603]

[0604] [Fifth Step] In the fifth step, a layer 113A was formed on the layer 111. Specifically, a material was evaporated by using a resistance heating method.

[0605] Note that layer 113A contains mPCCzPTzn-02 and has a thickness of 20 nm.

[0606] [Sixth Step] In the sixth step, the layer 113B was formed on the layer 113A. Specifically, the material was evaporated by using a resistance heating method.

[0607] The layer 113B contains NBPhen and has a thickness of 10 nm.

[0608] [Seventh Step] In the seventh step, the layer 105 was formed on the layer 113B. Specifically, the material was evaporated by using a resistance heating method.

[0609] The layer 105 contains LiF and has a thickness of 1 nm.

[0610] [Eighth Step] In the eighth step, the electrode 102 was formed on the layer 105. Specifically, a material was evaporated by using a resistance heating method.

[0611] The electrode 102 contains Al and has a thickness of 200 nm.

[0612] <Light-Emitting Device 331 (22)> The light-emitting device 331 (22) fabricated and described in this example has the same configuration as the light-emitting device 150 (see FIG. 17A).

[0613] <Configuration of the Light-Emitting Device 331 (22)> The light-emitting device 331 (22) is made of tris[2-[4-(tert-butyl)-2-pyridinyl-κN]phenyl-κC]iridium (abbreviation: Ir(4tBuppy) ３ ) is used as the energy donor material ED, which is different from the light-emitting device 321 (22).

[0614] Ir(4tBuppy) used in the organometallic complex of light-emitting device 331(22) ３ has the function of emitting phosphorescence (see FIG. 19). The phosphorescence has an end point at the shortest wavelength of the spectrum at 482 nm, and the end point is located at a wavelength shorter than 514 nm. ３ has a first HOMO level HOMO1 at -5.26 eV and a first LUMO level LUMO1 at -2.25 eV. The phosphorescence spectrum of a dichloromethane solution of the organometallic complex was measured at room temperature using a fluorometer (FP-8600 model, manufactured by JASCO Corporation). The HOMO level and LUMO level of the organometallic complex were calculated from the oxidation potential and reduction potential obtained by cyclic voltammetry (CV) measurement using an electrochemical analyzer (manufactured by BAS Inc., model number: ALS Model 600A or 600C).

[0615] The value of (LUMO2-HOMO2) is 2.63 eV, which is smaller than the value of (LUMO1-HOMO1), 3.01 eV.

[0616] <<Method of Fabricating Light-Emitting Device 331 (22)>> The light-emitting device 331 (22) described in this example was fabricated using a method having the following steps.

[0617] In the method for manufacturing the light-emitting device 331 (22), in the step of forming the layer 111, Ir(5tBuppy) ３ Replace with Ir (4tBuppy) ３The method of fabricating the light-emitting device 321 (22) differs from that of fabricating the light-emitting device 321 (22) in that the energy donor material ED is used. Here, the differences will be described in detail, and the above description will be used for the parts in which similar methods are used.

[0618] [Fourth Step] In the fourth step, the layer 111 was formed over the layer 112. Specifically, materials were co-evaporated by using a resistance heating method.

[0619] The layer 111 is made of mPCCzPTzn-02, PCCP, Ir (4tBuppy) ３ and TTPA to mPCCzPTzn-02:PCCP:Ir(4tBuppy) ３ :TTPA = 0.5:0.5:0.1:0.05 (weight ratio) and had a thickness of 40 nm (see Table 8).

[0620] <<Operation Characteristics of Light-Emitting Device 321(22) and Light-Emitting Device 331(22)>> When power was supplied, light-emitting device 321(22) and light-emitting device 331(22) emitted green light EL1 (see FIG. 17A). The operation characteristics of light-emitting device 321(22) and light-emitting device 331(22) were measured (see FIGS. 32 to 37). The luminance, CIE chromaticity, and emission spectrum were measured at room temperature using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0621] The fabricated light-emitting device had a brightness of 1000 cd / m ２ The main initial characteristics when the light-emitting device was driven to emit light at a constant current density (50 mA / cm ２ ) and the LT90, which is the time elapsed until the luminance decreased to 90% of the initial luminance, is shown in Table 4. Table 4 also shows the properties of other light-emitting devices whose configurations will be described later.

[0622] It was found that the light-emitting device 321 (22) and the light-emitting device 331 (22) exhibited good characteristics. For example, the light-emitting device 321 (22) and the light-emitting device 331 (22) emitted light with an emission spectrum originating from the light-emitting material FM, with a peak wavelength at approximately 540 nm (see FIG. 37). Furthermore, no light emission originating from the energy donor material ED was observed. Alternatively, energy was transferred from the energy donor material ED to the light-emitting material FM. Furthermore, undesired energy transfer from the energy donor material ED to the light-emitting material FM was suppressed. Furthermore, energy transfer due to the Dexter mechanism was suppressed.

[0623] Furthermore, the light-emitting device 321(22) and the light-emitting device 331(22) were able to emit 1000 cd / m at a lower voltage than the comparative device 311(22). ２ (See Table 4.) Furthermore, the device exhibited a higher external quantum efficiency than the comparative device 311 (22).

[0624] Also, 50 mA / cm ２ When light was emitted at a constant current density of 1000 kJ / s, the light-emitting devices 321(22) and 331(22) took longer to reduce their luminance to 90% of the initial luminance than the comparative device 311(22).

[0625] Reference Example 3 The comparative device 311 (22) prepared in this reference example was made of tris(2-phenylpyridinato-N,C ２’ ) Iridium (III) (abbreviation: Ir(ppy) ３ ) is used as the energy donor material ED, which is different from the light-emitting device 321 (22) and the light-emitting device 331 (22).

[0626] <Configuration of Comparative Device 311 (22)> The comparative device 311 (22) fabricated and explained in this reference example is made of Ir(ppy) ３ The light-emitting device 321 (22) differs from the light-emitting device 321 (22) in that the energy donor material ED is

[0627] Ir(ppy) used in the organometallic complex of light-emitting device 311 (22) ３has a ligand, and the ligand does not have an alkyl group, a cycloalkyl group, or a trialkylsilyl group.

[0628]

[0629] <<Method for Fabricating Comparative Device 311 (22)>> Comparative device 311 (22) was fabricated using a method having the following steps.

[0630] In the method for fabricating the comparative device 311 (22), in the step of forming the layer 111, Ir(5tBuppy) ３ Instead of Ir(ppy) ３ The method of fabricating the light-emitting device 321 (22) differs from that of fabricating the light-emitting device 321 (22) in that the energy donor material ED is used. Here, the differences will be described in detail, and the above description will be used for the parts in which similar methods are used.

[0631] [Fourth Step] In the fourth step, the layer 111 was formed over the layer 112. Specifically, materials were co-evaporated by using a resistance heating method.

[0632] The layer 111 is made of mPCCzPTzn-02, PCCP, Ir(ppy) ３ and TTPA to mPCCzPTzn-02:PCCP:Ir(ppy) ３ :TTPA = 0.5:0.5:0.1:0.05 (weight ratio) and had a thickness of 40 nm (see Table 8).

[0633] Reference Example 4 The fabricated Reference Device 2 described in this Reference Example differs from Reference Device 1 in the configuration of the layer 111. Specifically, Reference Device 2 differs from Reference Device 1 in that a mixed material containing mPCCzPTzn-02 and PCCP is used as the host material, instead of the configuration in which only mPCCzPTzn-02 is used as the host material.

[0634] <<Method for Producing Reference Device 2>> Reference Device 2 described in this example was produced using a method including the following steps.

[0635] The method for fabricating Reference Device 2 differs from the method for fabricating Reference Device 1 in the step of forming layer 111. Here, the differences will be described in detail, and the above description will be used for the parts where similar methods are used.

[0636] [Fourth Step] In the fourth step, the layer 111 was formed on the layer 112. Specifically, the material was evaporated by using a resistance heating method.

[0637] The layer 111 contains mPCCzPTzn-02 and PCCP in a weight ratio of mPCCzPTzn-02:PCCP=0.8:0.2, and has a thickness of 30 nm.

[0638] <<Operating Characteristics of Reference Device 2>> When power was supplied, Reference Device 2 emitted light EL1 (see FIG. 17A). The operating characteristics of Reference Device 2 were measured (see FIGS. 29 and 30). Note that a color luminance meter (BM-5A, manufactured by Topcon Corporation) was used to measure the luminance and CIE chromaticity, and a multichannel spectrometer (PMA-11, manufactured by Hamamatsu Photonics KK) was used to measure the emission spectrum, all at room temperature.

[0639] In addition, delayed fluorescence was measured using a picosecond fluorescence lifetime system (manufactured by Hamamatsu Photonics). ２ A voltage corresponding to the conditions shown in (1) was applied to Reference Device 2, a predetermined voltage was maintained in a rectangular pulse form for 100 μs, and the decay of delayed fluorescence was observed for 20 μs. A negative bias of −5 V was also applied during the period in which the decay of delayed fluorescence was observed. Measurements were repeated at a cycle of 10 Hz, and the data was integrated. The luminescence intensity of Reference Device 2 pulse-driven at a predetermined voltage is shown in FIG. 31.

[0640] Holes supplied from the electrode 101 and electrons supplied from the electrode 102 recombine in the layer 111, and light is emitted from the excited host material, specifically, the exciplex of mPCCzPTzn-02 and PCCP (see FIG. 30). Light emission from excitons with a short lifetime of 0.3 μs or less and light emission from excitons with a long lifetime of 4 μs were confirmed (see FIG. 31). This confirmed that singlet excitons are generated via triplet excitons with a long lifetime.

[0641] In this example, light-emitting devices 322(22) to 332(22) of one embodiment of the present invention will be described with reference to FIGS. 17 and 39 to 45. Note that in the figures and tables of this example, subscripts and superscripts are written in standard size for convenience. For example, subscripts used for abbreviations and superscripts used for units are written in standard size in the tables. The descriptions in these tables can be interpreted with reference to the description in the specification.

[0642] FIG. 39 is a diagram illustrating the current density-luminance characteristics of the light-emitting device 322(22) and the light-emitting device 332(22).

[0643] FIG. 40 is a diagram illustrating the luminance-current efficiency characteristics of the light-emitting device 322(22) and the light-emitting device 332(22).

[0644] FIG. 41 is a diagram illustrating the voltage-luminance characteristics of the light-emitting device 322(22) and the light-emitting device 332(22).

[0645] FIG. 42 is a diagram illustrating the voltage-current characteristics of the light-emitting device 322(22) and the light-emitting device 332(22).

[0646] 43 is a diagram illustrating the luminance-external quantum efficiency characteristics of the light-emitting device 322(22) and the light-emitting device 332(22). The external quantum efficiency was calculated from the luminance, assuming that the light distribution characteristics of the light-emitting device are Lambertian.

[0647] FIG. 44 shows the light emitting device 322(22) and the light emitting device 332(22) at 1000 cd / m ２ 10 is a diagram illustrating an emission spectrum when light is emitted at a luminance of 1000 .mu.m.

[0648] Figure 45 shows the current density at 50 mA / cm ２ 10 is a diagram illustrating the normalized luminance-time change characteristics when the light-emitting device 322(22) and the light-emitting device 332(22) are caused to emit light at a constant current density of 1000 .mu.m.

[0649] <Light-emitting device 322(22)> The light-emitting device 322(22) fabricated in this example has a configuration similar to that of the light-emitting device 150 (see FIG. 17A ). Note that the light-emitting device 322(22) differs from the light-emitting device 321(22) in that 2Ph-mmtBuDPhA2Anth was used as the light-emitting material FM.

[0650] The light-emitting material FM is a second substituent R ２ and the second substituent R ２ is any one of a methyl group, a branched alkyl group, a substituted or unsubstituted cycloalkyl group, and a trialkylsilyl group. The branched alkyl group has 3 to 12 carbon atoms, the cycloalkyl group has 3 to 10 carbon atoms forming a ring, and the trialkylsilyl group has 3 to 12 carbon atoms.

[0651] <Configuration of Light-Emitting Device 322 (22)> The light-emitting device 322 (22) fabricated and described in this example differs from the light-emitting device 321 (22) in that 2Ph-mmtBuDPhA2Anth is used as the light-emitting material FM.

[0652] The 2Ph-mmtBuDPhA2Anth used as the luminescent material FM of the light-emitting device 322 (22) has an edge at the longest wavelength of the absorption spectrum at a wavelength of 519 nm (see FIG. 20).

[0653] Ir(5tBuppy) used in organometallic complex of light-emitting device 322 (22) ３ has the ability to emit phosphorescence, which has an end at the shortest wavelength of the spectrum at a wavelength of 484 nm, and this end is located at a wavelength shorter than 519 nm.

[0654] <<Method of Fabricating Light-Emitting Device 322 (22)>> The light-emitting device 322 (22) was fabricated using a method having the following steps.

[0655] The method for fabricating the light-emitting device 322 (22) differs from the method for fabricating the light-emitting device 321 (22) in that 2Ph-mmtBuDPhA2Anth was used as the light-emitting material FM instead of TTPA in the step of forming the layer 111. Here, the differences will be described in detail, and the above description will be used for the parts where similar methods were used.

[0656] [Fourth Step] In the fourth step, the layer 111 was formed over the layer 112. Specifically, materials were co-evaporated by using a resistance heating method.

[0657] The layer 111 is made of mPCCzPTzn-02, PCCP, Ir (5tBuppy) ３ and 2Ph-mmtBuDPhA2Anth to mPCCzPTzn-02:PCCP:Ir(5tBuppy) ３ :2Ph-mmtBuDPhA2Anth=0.5:0.5:0.1:0.05 (weight ratio) and has a thickness of 40 nm.

[0658]

[0659] <Light-emitting device 332 (22)> The light-emitting device 332 (22) fabricated in this example has the same configuration as the light-emitting device 150 (see FIG. 17A). The light-emitting device 332 (22) is made of Ir (4tBuppy) ３ The light-emitting device 321 (22) differs from the light-emitting device 321 (22) in that the energy donor material ED is 2Ph-mmtBuDPhA2Anth and the light-emitting material FM is 2Ph-mmtBuDPhA2Anth.

[0660] <Configuration of the Light-Emitting Device 332 (22)> The light-emitting device 332 (22) fabricated in this example is made of Ir(4tBuppy) ３ The light-emitting device 321 (22) differs from the light-emitting device 321 (22) in that the energy donor material ED is 2Ph-mmtBuDPhA2Anth and the light-emitting material FM is 2Ph-mmtBuDPhA2Anth.

[0661] 2Ph-mmtBuDPhA2Anth used as the luminescent material FM of the light-emitting device 332 (22) has an edge at the longest wavelength of the absorption spectrum at a wavelength of 519 nm (see FIG. 21).

[0662] Ir(4tBuppy) used in organometallic complex of light-emitting device 332(22) ３ has the function of emitting phosphorescence. The phosphorescence has an end point at the shortest wavelength of the spectrum at a wavelength of 482 nm, and the end point is located at a wavelength shorter than 519 nm. ３ has a first HOMO level HOMO1 at −5.26 eV and a first LUMO level LUMO1 at −2.25 eV.

[0663] The value of (LUMO2-HOMO2) is 2.63 eV, which is smaller than the value of (LUMO1-HOMO1), 3.01 eV.

[0664] <<Method of Fabricating Light-Emitting Device 332 (22)>> The light-emitting device 332 (22) described in this example was fabricated using a method having the following steps.

[0665] In the method for manufacturing the light-emitting device 332 (22), in the step of forming the layer 111, Ir(5tBuppy) ３ Replace with Ir (4tBuppy) ３ The method of fabricating the light-emitting device 321 (22) differs from that of fabricating the light-emitting device 321 (22) in that the energy donor material ED was replaced with 2Ph-mmtBuDPhA2Anth instead of TTPA as the light-emitting material FM. Here, the differences will be described in detail, and the above description will be used for the parts in which similar methods were used.

[0666] [Fourth Step] In the fourth step, the layer 111 was formed over the layer 112. Specifically, materials were co-evaporated by using a resistance heating method.

[0667] The layer 111 is made of mPCCzPTzn-02, PCCP, Ir (4tBuppy) ３ and 2Ph-mmtBuDPhA2Anth to mPCCzPTzn-02:PCCP:Ir(4tBuppy) ３ :2Ph-mmtBuDPhA2Anth=0.5:0.5:0.1:0.05 (weight ratio) and had a thickness of 40 nm (see Table 9).

[0668] <<Operation Characteristics of Light-Emitting Device 322(22) and Light-Emitting Device 332(22)>> When power was supplied, light-emitting device 322(22) and light-emitting device 332(22) emitted green light EL1 (see FIG. 17A). The operation characteristics of light-emitting device 322(22) and light-emitting device 332(22) were measured (see FIGS. 39 to 44). The luminance, CIE chromaticity, and emission spectrum were measured at room temperature using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0669] The light-emitting device 322 (22) and the light-emitting device 332 (22) were illuminated at a luminance of 1000 cd / m ２ The main initial characteristics when the light-emitting device was driven to emit light at a constant current density (50 mA / cm ２ ) and LT90, which is the time elapsed until the luminance decreased to 90% of the initial luminance, is shown in Table 4.

[0670] It was found that the light-emitting device 322 (22) and the light-emitting device 332 (22) exhibited good characteristics. For example, the light-emitting device 322 (22) and the light-emitting device 332 (22) emitted light with an emission spectrum originating from the light-emitting material FM, with a peak wavelength at approximately 540 nm (see FIG. 44). Furthermore, no emission originating from the energy donor material ED was observed. Alternatively, energy was transferred from the energy donor material ED to the light-emitting material FM. Furthermore, undesired energy transfer from the energy donor material ED to the light-emitting material FM was suppressed. Furthermore, energy transfer due to the Dexter mechanism was suppressed.

[0671] Furthermore, the light-emitting device 322(22) and the light-emitting device 332(22) were able to emit 1000 cd / m at a lower voltage than the comparative device 312(22). ２ (See Table 4.) Furthermore, the device exhibited a higher external quantum efficiency than the comparative device 312 (22).

[0672] Also, 50 mA / cm ２When light was emitted at a constant current density of 1000 kJ / s, the light-emitting devices 322(22) and 332(22) had a longer time until their normalized luminance decreased to 90% of the initial luminance than the comparative device 312(22), demonstrating higher reliability (see FIG. 45).

[0673] The light-emitting device according to one embodiment of the present invention can achieve higher reliability in an environment of 65° C. than conventional light-emitting devices. For example, a light-emitting device emitting green light has a luminance of 29000 cd / m ２ It is expected that light-emitting device B will have twice the reliability of conventional light-emitting device A in terms of the time it takes for the luminance to decrease to 90% of the initial luminance when the device is lit at a temperature of about 1000 .mu.m (see FIG. 46).

[0674] Reference Example 5 The comparative device 312 (22) prepared in this reference example was made of tris(2-phenylpyridinato-N,C ２’ ) Iridium (III) (abbreviation: Ir(ppy) ３ ) is used as the energy donor material ED.

[0675] <Configuration of Comparative Device 312 (22)> The comparative device 312 (22) fabricated and explained in this reference example is Ir(ppy) ３ was used as the energy donor material ED.

[0676] <Configuration of Comparative Device 312 (22)> The comparative device 312 (22) fabricated and explained in this reference example is made of Ir(ppy) ３ was used as the energy donor material ED.

[0677] <<Method of Fabricating Comparative Device 312 (22)>> Comparative device 312 (22) was fabricated using a method having the following steps.

[0678] In the method for fabricating the comparative device 312 (22), in the step of forming the layer 111, Ir(5tBuppy) ３ Instead of Ir(ppy) ３The method of fabricating the light-emitting device 321 (22) differs from that of fabricating the light-emitting device 321 (22) in that the energy donor material ED was replaced with 2Ph-mmtBuDPhA2Anth instead of TTPA as the light-emitting material FM. Here, the differences will be described in detail, and the above description will be used for the parts in which similar methods were used.

[0679] [Fourth Step] In the fourth step, the layer 111 was formed over the layer 112. Specifically, materials were co-evaporated by using a resistance heating method.

[0680] The layer 111 is made of mPCCzPTzn-02, PCCP, Ir(ppy) ３ and 2Ph-mmtBuDPhA2Anth to mPCCzPTzn-02:PCCP:Ir(ppy) ３ :2Ph-mmtBuDPhA2Anth=0.5:0.5:0.1:0.05 (weight ratio) and had a thickness of 40 nm (see Table 9).

[0681] 101: electrode, 101S: electrode, 102: electrode, 103: unit, 103S: unit, 104: layer, 105: layer, 106: intermediate layer, 106A: layer, 106B: layer, 111: layer, 112: layer, 113: layer, 113A: layer, 113B: layer, 114: layer, 114N: layer, 114P: layer, 150: light-emitting device, 170: optical functional device, 400: substrate, 401: electrode, 403: EL layer, 404: electrode, 405: sealing material, 406: sealing material, 407: sealing substrate, 412: pad, 420: IC chip, 521: insulating film, 528: insulating film, 573: insulating film, 5 73A: insulating film, 573B: insulating film, 601: source line driving circuit, 602: pixel portion, 603: gate line driving circuit, 604: sealing substrate, 605: sealing material, 607: space, 608: wiring, 609: FPC, 610: element substrate, 611: switching FET, 612: current control FET, 613: electrode, 614: insulator, 616: EL layer, 617: electrode, 618: light-emitting device, 623: FET, 700: functional panel, 951: substrate, 952: electrode, 953: insulating layer, 954: partition layer, 955: EL layer, 956: electrode, 1001: substrate, 1002: base insulating film , 1003: gate insulating film, 1006: gate electrode, 1007: gate electrode, 1008: gate electrode, 1020: interlayer insulating film, 1021: interlayer insulating film, 1022: electrode, 1024B: electrode, 1024G: electrode, 1024R: electrode, 1024W: electrode, 1025: partition wall, 1028: EL layer, 1029: electrode, 1031: sealing substrate, 1032: sealing material, 1033: base material, 1034B: colored layer, 1034G: colored layer, 1034R: colored layer, 1035: black matrix, 1036: overcoat layer, 1037: interlayer insulating film, 1040: pixel portion, 1041: Drive circuit unit, 1042: peripheral unit, 2001: housing, 2002: light source, 2100: robot, 2101: illuminance sensor, 2102: microphone, 2103: upper camera, 2104: speaker, 2105: display, 2106: lower camera, 2107: obstacle sensor, 2108: movement mechanism, 2110: computing unit, 3001: lighting device, 5000: housing, 5001: display unit, 5002: display unit, 5003: speaker, 5004: LED lamp, 5006: connection terminal, 5007: sensor, 5008: microphone, 5012: support unit, 5013: earphone,5100: cleaning robot, 5101: display, 5102: camera, 5103: brush, 5104: operation button, 5120: dust, 5140: portable electronic device, 5200: display area, 5201: display area, 5202: display area, 5203: display area, 7101: housing, 7103: display unit, 7105: stand, 7107: display unit, 7109: operation key, 7110: remote control unit, 7 201: main body, 7202: housing, 7203: display unit, 7204: keyboard, 7205: external connection port, 7206: pointing device, 7210: display unit, 7401: housing, 7402: display unit, 7403: operation buttons, 7404: external connection port, 7405: speaker, 7406: microphone, 9310: mobile information terminal, 9311: display panel, 9313: hinge, 9315: housing,

Claims

1. a first layer including a light-emitting material, a first organic compound, and a first material between a first electrode and a second electrode; The light-emitting material has a function of emitting fluorescence, the luminescent material has an absorption spectrum edge at a first wavelength that is located at the longest wavelength; the first organic compound has a function of converting triplet excitation energy into luminescence, the emission of the first organic compound has an edge at a second wavelength that is located at the shortest wavelength of the spectrum; The second wavelength is shorter than the first wavelength, the first organic compound comprises a first substituent; the first substituent is any one of an alkyl group, a substituted or unsubstituted cycloalkyl group, and a trialkylsilyl group; The alkyl group has 3 to 12 carbon atoms. The cycloalkyl group has 3 to 10 carbon atoms forming a ring, The trialkylsilyl group has 3 to 12 carbon atoms, The first material has a function of emitting delayed fluorescence at room temperature.

2. A light-emitting device comprising: a first layer including a light-emitting material, a first organic compound, and a first material between a first electrode and a second electrode; The light-emitting material has a function of emitting fluorescence, the luminescent material has an absorption spectrum edge at a first wavelength that is located at the longest wavelength; the first organic compound has a function of converting triplet excitation energy into luminescence, the emission of the first organic compound has an edge at a second wavelength that is located at the shortest wavelength of the spectrum; The second wavelength is shorter than the first wavelength, the first organic compound comprises a first substituent; the first substituent is any one of an alkyl group, a substituted or unsubstituted cycloalkyl group, and a trialkylsilyl group; The alkyl group has 3 to 12 carbon atoms. The cycloalkyl group has 3 to 10 carbon atoms forming a ring, The trialkylsilyl group has 3 to 12 carbon atoms, the first material is composed of a second organic compound and a third organic compound; A light-emitting device, wherein the second organic compound and the third organic compound are a combination that forms an exciplex.

3. In claim 1 or claim 2, the first organic compound has a first HOMO level HOMO1 and a first LUMO level LUMO1; the first material has a second HOMO level HOMO2 and a second LUMO level LUMO2; A light-emitting device, wherein the first HOMO level HOMO1, the first LUMO level LUMO1, the second HOMO level HOMO2, and the second LUMO level LUMO2 satisfy the following formula (1): [0010]

4. In any one of claims 1 to 3, the light-emitting material comprises a second substituent; the second substituent is any one of a methyl group, a branched alkyl group, a substituted or unsubstituted cycloalkyl group, and a trialkylsilyl group; The branched alkyl group has 3 to 12 carbon atoms, The cycloalkyl group has 3 to 10 carbon atoms forming a ring, The trialkylsilyl group has 3 or more and 12 or less carbon atoms.

5. In any one of claims 1 to 3, the light-emitting material comprises five or more second substituents; at least five of the five or more second substituents are each independently any one of a branched alkyl group, a substituted or unsubstituted cycloalkyl group, and a trialkylsilyl group; The branched alkyl group has 3 to 12 carbon atoms, The cycloalkyl group has 3 to 10 carbon atoms forming a ring, The trialkylsilyl group has 3 or more and 12 or less carbon atoms.

6. In any one of claims 1 to 5, the luminescent material has a third LUMO level; The third LUMO level is higher than the second LUMO level, LUMO2.

7. In any one of claims 1 to 6, the second HOMO level HOMO2 is higher than the first HOMO level HOMO1; The second LUMO level LUMO2 is lower than the first LUMO level LUMO1.

8. In any one of claims 1 to 6, A light emitting device, wherein the first HOMO level HOMO1 is higher than the second HOMO level HOMO2.

9. In any one of claims 1 to 6, A light emitting device, wherein the first LUMO level LUMO1 is lower than the second LUMO level LUMO2.

10. A light emitting apparatus comprising the light emitting device according to claim 1 and a transistor or a substrate.

11. A display device comprising the light-emitting device according to claim 1 and a transistor or a substrate.

12. A lighting device comprising the light-emitting device according to claim 10 and a housing.

13. 12. An electronic device comprising: the display device according to claim 11; and at least one of a sensor, an operation button, a speaker, and a microphone.

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