Light-emitting element, display device, electronic device and lighting device

Abstract

Light-emitting element (150; 250; 252; 260a; 260b; 262a; 262b), comprising: a light-emitting layer (120; 130; 160; 170; 180; 190), wherein the light-emitting layer (120; 130; 160; 170; 180; 190) comprises a first organic compound (131_1; 171_1), a second organic compound (131_2; 171_2) and a guest material (122; 132; 172), where a lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) is lower than a lowest unoccupied molecular orbital level of the second organic compound (131_2; 171_2), where a highest occupied molecular orbital level of the guest material (122; 132; 172) is higher than a highest occupied molecular orbital level of the second organic compound (131_2; 171_2), where an energy difference between a lowest unoccupied molecular orbital level of the guest material (122; 132; 172) and the highest occupied molecular orbital level of the guest material (122; 132; 172) is greater than an energy difference between the lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) and the highest occupied molecular orbital level of the second organic compound (131_2; 171_2), where the guest material (122; 132; 172) converts triplet excitation energy into a light emission, wherein the first organic compound (131_1; 171_1) and the second organic compound (131_2; 171_2) form an exciplex, wherein a maximum peak of an emission spectrum of a mixed thin film of the first organic compound (131_1; 171_1) and the second organic compound (131_2; 171_2) has a longer wavelength than a maximum peak of an emission spectrum of a thin film of the first organic compound (131_1; 171_1) and a maximum peak of an emission spectrum of a thin film of the second organic compound (131_2; 171_2), respectively, and wherein the first organic compound (131_1; 171_1) comprises a triazine skeleton.

Description

Technical field

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

[0002] It should be noted that an embodiment of the present invention is not limited to the aforementioned technical field. The technical field of an embodiment of the invention disclosed in this description and the like relates to an object, a method, or a manufacturing process. An embodiment of the present invention further relates to a process, a machine, a product, or a composition. In particular, examples of the technical field of an embodiment of the present invention disclosed in this description include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, an energy storage device, a storage device, a method for controlling any of them, and a method for manufacturing any of them. State of the art

[0003] In recent years, intensive research and development have been conducted on light-emitting elements that utilize electroluminescence (EL). In a basic structure of such a light-emitting element, a layer containing a light-emitting material (an EL layer) is positioned between a pair of electrodes. By applying a voltage between the electrode pair of this element, light emission can be obtained from the light-emitting material.

[0004] Since the aforementioned light-emitting element is of a self-illuminating type, a display device using this light-emitting element offers the following advantages: high visibility, no need for backlighting, low power consumption, and the like. The display device is also advantageous in that it can be made thin and lightweight and exhibits a high response speed.

[0005] In a light-emitting element (e.g., an organic EL element) whose EL layer contains an organic material as the light-emitting material and is positioned between a pair of electrodes, applying a voltage between the electrode pair causes the injection of electrons from a cathode and holes from an anode into the light-emitting EL layer, thereby generating a current. As a result of recombination of the injected electrons and holes, the light-emitting organic material is excited to a state that produces light emission.

[0006] It should be noted that an excitation state formed by an organic material can be a singlet excitation state (S*) or a triplet excitation state (T*). Light emission from the singlet excitation state is called fluorescence, and light emission from the triplet excitation state is called phosphorescence. The S* to T* generation ratio in the light-emitting element is 1:3. In other words, a light-emitting element containing a phosphorescent material has a higher light emission efficiency than a light-emitting element containing a fluorescent material.Consequently, light-emitting elements containing phosphorescent materials capable of converting triplet excitation energy into light emission have been actively developed in recent years (see, for example, patent document 1).

[0007] The energy required to excite an organic material depends on the energy difference between the LUMO (lowest unoccupied molecular orbital) and HOMO (highest occupied molecular orbital) levels of the organic material. This energy difference is approximately equal to the singlet excitation energy. In a light-emitting element containing an organic material that emits phosphorescence, the triplet excitation energy is converted into light emission energy. Consequently, if the organic material has a large difference between its singlet and triplet excitation energies, the energy required to excite the organic material will be higher than the light emission energy by the amount of this energy difference.The difference between the energy required to excite the organic material and the light emission energy affects the properties of a light-emitting element: the drive voltage of the light-emitting element increases. A technique to prevent such an increase in the drive voltage is developed (see patent document 2). Further examples of light-emitting elements are disclosed in patent documents 3 to 5 and non-patent documents 1 and 2.

[0008] Among light-emitting elements containing phosphorescent materials, a blue-emitting element has not yet been used in practice because it is difficult to develop a stable compound with a high triplet excitation energy level. Consequently, the development of a stable phosphorescent material with high emission efficiency and a highly reliable phosphorescent light-emitting element with high emission efficiency is necessary. [Reference] [Patent document 1] JP 2010 - 182 699 A [Patent document 2] JP 2012 - 212 879 A [Patent document 3] US 2013 / 0 277 656 A1 [Patent document 4] US 2013 / 0 292 656 A1 [Patent Document 5] JP 2014 - 152 151 A [Non-Patent Document 1] D.-Y. Zhou et al., J. Phys. Chem. C 2014, 118, 24006-24012. [Non-Patent Document 2] J.-H. Lee et al., Adv. Funct. Mater. 2015, 25, 361-366. Disclosure of the invention

[0009] An iridium complex is known as a phosphorescent material with high emission efficiency. An iridium complex comprising a pyridine framework or a five-membered nitrogenous heterocyclic framework in a ligand is known as an iridium complex with high light emission energy. Although the pyridine framework and the five-membered nitrogenous heterocyclic framework exhibit high triplet excitation energies, they have poor electron-accepting properties. Accordingly, the HOMO and LUMO levels of the iridium complex with the framework in a ligand are high, and hole charge carriers are readily injected into the iridium complex, whereas this is not the case for electron charge carriers.As a result, in some cases it is difficult to obtain excitation by direct recombination of charge carriers or efficient light emission from a light-emitting element when an iridium complex with a high light emission energy is used.

[0010] In light of the foregoing, one object of an embodiment of the present invention is to provide a light-emitting element that contains a phosphorescent material and has high emission efficiency. Another object of an embodiment of the present invention is to provide a light-emitting element with reduced power consumption. Another object of an embodiment of the present invention is to provide a highly reliable light-emitting element. Another object of an embodiment of the present invention is to provide a novel light-emitting element. Another object of an embodiment of the present invention is to provide a novel light-emitting device. Another object of an embodiment of the present invention is to provide a novel display device.

[0011] It should be noted that the description of these problems does not preclude the existence of further problems. In one embodiment of the present invention, it is unnecessary to achieve all of the problems. Further problems will become apparent from the explanation of the description and the like, and can be derived from it.

[0012] One embodiment of the present invention is a light-emitting element containing an exciplex that can efficiently excite a phosphorescent material.

[0013] Therefore, one embodiment of the present invention is a light-emitting element comprising a light-emitting layer, wherein the light-emitting layer contains a first organic compound, a second organic compound, and a guest material, the first organic compound comprising a triazine backbone. The LUMO level of the first organic compound is lower than that of the second organic compound. The HOMO level of the first organic compound is lower than that of the second organic compound. The HOMO level of the guest material is higher than that of the second organic compound. The energy difference between the LUMO level of the guest material and the HOMO level of the guest material is greater than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound.The guest material exhibits a function for converting triplet excitation energy into light emission. A combination of the first organic compound and the second organic compound forms an exciplex. A maximum peak of an emission spectrum of a mixed thin film consisting of the first organic compound and the second organic compound has a longer wavelength than, respectively, a maximum peak of an emission spectrum of a thin film of the first organic compound and a maximum peak of an emission spectrum of a thin film of the second organic compound.

[0014] In the above structure, the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound is preferably greater than or equal to a transition energy calculated from an absorption edge of an absorption spectrum of the guest material. Preferably, the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound is greater than or equal to the light emission energy of the guest material.

[0015] Another embodiment of the present invention is a light-emitting element comprising a light-emitting layer, wherein the light-emitting layer contains a first organic compound, a second organic compound, and a guest material, the first organic compound comprising a triazine backbone. The LUMO level of the first organic compound is lower than that of the second organic compound. The HOMO level of the first organic compound is lower than that of the second organic compound. The HOMO level of the guest material is higher than that of the second organic compound. The energy difference between the LUMO level of the guest material and the HOMO level of the guest material is greater than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound.The guest material possesses a function for converting triplet excitation energy into light emission. A combination of the first organic compound and the second organic compound forms an exciplex. An energy difference between the LUMO level of the first organic compound and the HOMO level of the guest material is greater than or equal to a transition energy calculated from an absorption edge of an absorption spectrum of the guest material.

[0016] Another embodiment of the present invention is a light-emitting element comprising a light-emitting layer, wherein the light-emitting layer contains a first organic compound, a second organic compound, and a guest material, the first organic compound comprising a triazine backbone. The LUMO level of the first organic compound is lower than that of the second organic compound. The HOMO level of the first organic compound is lower than that of the second organic compound. The HOMO level of the guest material is higher than that of the second organic compound. The energy difference between the LUMO level of the guest material and the HOMO level of the guest material is greater than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound.The guest material possesses a function for converting triplet excitation energy into light emission. A combination of the first organic compound and the second organic compound forms an exciplex. An energy difference between the LUMO level of the first organic compound and the HOMO level of the guest material is greater than or equal to the light emission energy of the guest material. A maximum peak of an emission spectrum of a mixed thin film of the first organic compound and the second organic compound has a longer wavelength than, respectively, a maximum peak of an emission spectrum of a thin film of the first organic compound and a maximum peak of an emission spectrum of a thin film of the second organic compound.

[0017] In each of the above structures, the energy difference between the LUMO level of the guest material and the HOMO level of the guest material is preferably 0.3 eV or more greater than the transition energy calculated from the absorption edge of the absorption spectrum of the guest material.

[0018] In each of the above structures, the energy difference between the LUMO level of the guest material and the HOMO level of the guest material is preferably greater than the light emission energy of the guest material by 0.3 eV or more.

[0019] In each of the aforementioned structures, the exciplex preferably has a function for transferring excitation energy to the guest material. Furthermore, an emission spectrum of the exciplex preferably includes a region that overlaps an absorption band on the longest wavelength side of the absorption spectrum of the guest material.

[0020] In each of the above structures, the guest material preferably contains iridium.

[0021] In each of the above structures, the guest material preferably contains a ligand coordinated to the iridium, wherein the ligand comprises a cyano group and a five-membered nitrogen-containing heterocyclic framework. Preferably, the ligand comprises a cyano group and a triazole framework.

[0022] In each of the aforementioned structures, the first organic compound preferably has an electron-transporting function, and the second organic compound preferably has a hole-transporting function. The first organic compound preferably comprises a framework with a π-electron-deficient heteroaromatic ring, and the second organic compound preferably comprises a framework with a π-electron-rich heteroaromatic ring and / or an aromatic amine framework.

[0023] In another embodiment of the present invention, a display device comprises the light-emitting element having one of the structures described above and a color filter and / or a transistor. In another embodiment of the present invention, an electronic device comprises the display device described above and a housing and / or a touch sensor. In another embodiment of the present invention, a lighting device comprises the light-emitting element having one of the structures described above and a housing and / or a touch sensor. The category of embodiments of the present invention includes not only a light-emitting device comprising a light-emitting element, but also an electronic device comprising a light-emitting device.The light-emitting device in this description refers to an image display device and a light source (e.g., a lighting device). A display module in which a connecting element, such as a flexible printed circuit (FPC) or a tape carrier package (TCP), is connected to a light-emitting device, a display module in which a printed circuit board is provided on top of a TCP, and a display module in which an integrated circuit (IC) is directly attached to a light-emitting element by a chip-on-glass (COG) process are also embodiments of the present invention.

[0024] In one embodiment of the present invention, a light-emitting element can be provided which contains a phosphorescent material and has high emission efficiency. In one embodiment of the present invention, a light-emitting element with reduced power consumption can be provided. In one embodiment of the present invention, a highly reliable light-emitting element can be provided. In one embodiment of the present invention, a novel light-emitting element can be provided. In one embodiment of the present invention, a novel light-emitting device can be provided. In one embodiment of the present invention, a novel display device can be provided.

[0025] It should be noted that the description of these effects does not preclude the existence of further effects. An embodiment of the present invention does not necessarily exhibit all of the effects described above. Further effects will become apparent from the explanation of the description, the drawings, the claims, and the like, and can be derived from them. Brief description of the drawings Fig. 1A and Fig. Figure 1B shows schematic cross-sectional views of a light-emitting element of an embodiment of the present invention. Fig. 2A and Fig. Figure 2B shows a correlation of energy bands and a correlation of energy levels in a light-emitting layer of a light-emitting element of an embodiment of the present invention. Fig. 3A to Fig. Figures 3C are schematic cross-sectional views of a light-emitting element of an embodiment of the present invention and a diagram showing a correlation of energy levels. Fig. 4A to Fig. Figures 4C are schematic cross-sectional views of a light-emitting element of an embodiment of the present invention and a diagram showing a correlation of energy levels. Fig. 5A and Fig. Figures 5B are each a schematic cross-sectional view of a light-emitting element of an embodiment of the present invention. Fig. 6A and Fig. Figure 6B each shows a schematic cross-sectional view of a light-emitting element of an embodiment of the present invention. Fig. 7A to Fig. Figure 7C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting element of an embodiment of the present invention. Fig. 8A to Fig. Figure 8C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting element of an embodiment of the present invention. Fig. 9A and Fig. Figure 9B shows a top view and a schematic cross-sectional view representing a display device of an embodiment of the present invention. Fig. 10A and Fig. Figures 10B are schematic cross-sectional views, each representing a display device of an embodiment of the present invention. Fig. Figure 11 is a schematic cross-sectional view representing a display device of an embodiment of the present invention. Fig. 12A and Fig. Figures 12B are schematic cross-sectional views, each representing a display device of an embodiment of the present invention. Fig. 13A and Fig. Figure 13B are schematic cross-sectional views, each representing a display device of an embodiment of the present invention. Fig. Figure 14 is a schematic cross-sectional view representing a display device of an embodiment of the present invention. Fig. 15A and Fig. Figure 15B are schematic cross-sectional views, each representing a display device of an embodiment of the present invention. Fig. Figure 16 is a schematic cross-sectional view representing a display device of an embodiment of the present invention. Fig. 17A and Fig. Figure 17B are schematic cross-sectional views, each representing a display device of an embodiment of the present invention. Fig. 18A and Fig. Figure 18B is a block diagram and a circuit diagram representing a display device of an embodiment of the present invention. Fig. 19A and Fig. Figure 19B are circuit diagrams, each representing a pixel circuit of a display device of an embodiment of the present invention. Fig. 20A and Fig. Figures 20B are circuit diagrams, each representing a pixel circuit of a display device of an embodiment of the present invention. Fig. 21A and Fig. Figure 21B shows perspective views illustrating an example of a touchscreen in an embodiment of the present invention. Fig. 22A to Fig. Figures 22C are cross-sectional views showing examples of a display device and a touch sensor of embodiments of the present invention. Fig. 23A and Fig. Figures 23B are cross-sectional views, each representing an example of a touchscreen of an embodiment of the present invention. Fig. 24A and Fig. Figures 24B are a block diagram and a timing diagram of a touch sensor of an embodiment of the present invention. Fig. Figure 25 is a circuit diagram of a touch sensor of an embodiment of the present invention. Fig. Figure 26 is a perspective view showing a display module of an embodiment of the present invention. Fig. 27A to Fig. 27G represent electronic devices of embodiments of the present invention. Fig. 28A to Fig. 28D represent electronic devices of embodiments of the present invention. Fig. 29A and Fig. Figure 29B are perspective views showing a display device of an embodiment of the present invention. Fig. 30A to Fig. Figures 30C are a perspective view and cross-sectional views representing a light-emitting device of an embodiment of the present invention. Fig. 31A to Fig. Figures 31D are cross-sectional views, each representing a light-emitting device of an embodiment of the present invention. Fig. 32A and Fig. 32B represent an electronic device of an embodiment of the present invention and Fig. 32C represents a lighting device of an embodiment of the present invention. Fig. Figure 33 represents lighting devices of embodiments of the present invention. Fig. Figure 34 is a schematic cross-sectional view representing a light-emitting element in the example. Fig. Figure 35 shows curves that depict the emission spectra of host materials in the example. Fig. 36A and Fig. Figures 36B are curves that each show absorption and emission spectra of a guest material in the example. Fig. Figure 37 shows curves that display phosphorescence spectra of host materials in the example. Fig. Figure 38 shows curves that demonstrate the power efficiency-luminance properties of light-emitting elements in the example. Fig. Figure 39 shows curves that depict luminance-voltage properties of light-emitting elements in the example. Fig. Figure 40 shows curves that represent external quantum efficiency luminance properties of light-emitting elements in the example. Fig. Figure 41 shows curves that depict the power efficiency-luminance properties of light-emitting elements in the example. Fig. Figure 42 shows curves that represent electroluminescence spectra of light-emitting elements in the example. Fig. Figure 43 shows curves that represent the results of the reliability tests of light-emitting elements in the example. Fig. Figure 44 shows curves that depict the emission spectra of host materials in the example. Fig. 45A and Fig. 45B are curves showing absorption and emission spectra of guest materials in the example. Fig. Figure 46 shows curves that represent the power efficiency-luminance properties of light-emitting elements in the example. Fig. Figure 47 shows curves that depict luminance-voltage properties of light-emitting elements in the example. Fig. Figure 48 shows curves that represent external quantum efficiency luminance properties of light-emitting elements in the example. Fig. Figure 49 shows curves that depict the power efficiency-luminance properties of light-emitting elements in the example. Fig. Figure 50 shows curves that represent electroluminescence spectra of light-emitting elements in the example. Fig. 51A and Fig. Figures 51B each show a correlation of energy bands in the example. Fig. Figure 52 shows curves that represent the results of the reliability tests of light-emitting elements in the example. Fig. Figure 53 shows curves that represent the absorption and emission spectra of a guest material in the example. Fig. Figure 54 shows curves that represent the absorption and emission spectra of a guest material in the example. Fig. Figure 55 shows curves that represent the absorption and emission spectra of a guest material in the example. Fig. Figure 56 shows curves that illustrate the power efficiency-luminance properties of light-emitting elements in the example. Fig. Figure 57 shows curves that depict luminance-voltage properties of light-emitting elements in the example. Fig. Figure 58 shows curves that represent external quantum efficiency luminance properties of light-emitting elements in the example. Fig. Figure 59 shows curves that depict the power efficiency-luminance properties of light-emitting elements in the example. Fig. Figure 60 shows curves that represent electroluminescence spectra of light-emitting elements in the example. Fig. Figure 61 shows curves that depict the emission spectra of host materials in the example. Fig. Figure 62 is a curve that shows an absorption spectrum of a guest material in the example. Fig. Figure 63 is a curve that shows a phosphorescence spectrum of a host material in the example. Fig. Figure 64 is a curve that shows the power efficiency-luminance properties of a light-emitting element in the example. Fig. 65 is a curve that shows luminance-voltage properties of a light-emitting element in the example. Fig. Figure 66 is a curve that shows external quantum efficiency luminance properties of a light-emitting element in the example. Fig. Figure 67 is a curve that shows the power efficiency-luminance properties of a light-emitting element in the example. Fig. Figure 68 is a curve that shows an electroluminescence spectrum of a light-emitting element in the example. Fig. Figure 69 shows curves that represent the absorption and emission spectra of a guest material in the example. Fig. 70 is a curve that shows the power efficiency-luminance properties of a light-emitting element in the example. Fig. 71 is a curve that shows luminance-voltage properties of a light-emitting element in the example. Fig. 72 is a curve that shows external quantum efficiency luminance properties of a light-emitting element in the example. Fig. 73 is a curve that shows the power efficiency-luminance properties of a light-emitting element in the example. Fig. Figure 74 is a curve that shows an electroluminescence spectrum of a light-emitting element in the example. Fig. Figure 75 shows the power efficiency-luminance properties of light-emitting elements in the example. Fig. Figure 76 shows curves that depict luminance-voltage properties of light-emitting elements in the example. Fig. Figure 77 shows curves that represent external quantum efficiency luminance properties of light-emitting elements in the example. Fig. Figure 78 shows curves that demonstrate the power efficiency-luminance properties of light-emitting elements in the example. Fig. Figure 79 shows curves that represent electroluminescence spectra of light-emitting elements in the example. Fig. 80 are curves that show emission spectra of host materials in the example. Fig. Figure 81 shows curves that illustrate the power efficiency-luminance properties of light-emitting elements in the example. Fig. Figure 82 shows curves that depict luminance-voltage properties of light-emitting elements in the example. Fig. Figure 83 shows curves that represent external quantum efficiency luminance properties of light-emitting elements in the example. Fig. Figure 84 shows curves that represent electroluminescence spectra of light-emitting elements in the example. Fig. Figure 85 shows curves that represent the absorption and emission spectra of a guest material in the example. Fig. Figure 86 shows curves that display phosphorescence spectra of host materials in the example. Fig. Figure 87 shows curves that represent the results of the reliability tests of light-emitting elements in the example. Fig. Figure 88 shows curves that represent the power efficiency-luminance properties of a light-emitting element in the example. Fig. Figure 89 shows curves that represent luminance-voltage properties of a light-emitting element in the example. Fig. Figure 90 is a curve showing external quantum efficiency luminance properties of a light-emitting element in the example. Fig. Figure 91 shows curves that represent the power efficiency-luminance properties of a light-emitting element in the example. Fig. Figure 92 is a curve that shows an electroluminescence spectrum of a light-emitting element in the example. Fig. Figure 93 is a curve that shows a phosphorescence spectrum of a host material in the example. Best way to implement the invention

[0026] Embodiments of the present invention are described in detail below with reference to the drawings. However, the present invention is not limited to the description given below, and its modes and details can be modified in various ways without departing from the essence and scope of the present invention. Therefore, the present invention should not be considered as limited to the content of the following embodiments.

[0027] It should be noted that, for the sake of simplicity, the position, size, area, or the like of any structure shown in drawings and the like is not always precisely depicted. The disclosed invention is therefore not necessarily limited to the position, size, area, or the like shown in the drawings and the like.

[0028] It should be noted that ordinal numbers, such as "first," "second," and the like, are used in this description and the like for the sake of simplicity, and they do not indicate the sequence of steps or the order in which the layers are arranged. Therefore, for example, an adequate description may be given even if "first" is replaced by "second" or "third." Furthermore, the ordinal numbers in this description and the like are not necessarily the same as those that specify an embodiment of the present invention.

[0029] In the explanations of the modes of the present invention in this description and the like, which are based on the drawings, in some cases identical components in different drawings are generally provided with the same reference numerals.

[0030] In this description and similar texts, the terms "film" and "layer" may be used interchangeably. For example, in some cases, the term "conducting layer" may be replaced by the term "conducting film." Similarly, in some cases, the term "insulating film" may be replaced by the term "insulating layer."

[0031] In this description and the like, a singlet excitation state (S*) denotes a singlet state with excitation energy . An S1 level denotes the lowest level of the singlet excitation energy levels, i.e., the excitation energy level of the lowest singlet excitation state. A triplet excitation state (T*) denotes a triplet state with excitation energy . A T1 level denotes the lowest level of the triplet excitation energy levels, i.e., the excitation energy level of the lowest triplet excitation state. It should be noted that in this description and the like, a singlet excitation state and a singlet excitation energy level sometimes refer to the lowest singlet excitation state and the S1 level, respectively. A triplet excitation state and a triplet excitation energy level sometimes refer to the lowest triplet excitation state and the T1 level, respectively.

[0032] In this description and similar usage, a fluorescent material refers to a material that emits light in the visible spectrum when it relaxes from the singlet excitation state to the ground state. A phosphorescent material refers to a material that emits light in the visible spectrum at room temperature when it relaxes from the triplet excitation state to the ground state. That is, a phosphorescent material refers to a material that can convert triplet excitation energy into visible light.

[0033] Phosphorescence emission energy, or triplet excitation energy, can be obtained from the wavelength of an emission peak (including a shoulder) on the shortest wavelength side of the phosphorescence emission. It should be noted that phosphorescence emission in a low-temperature environment (e.g., 10 K) can be observed by time-resolved photoluminescence. Thermally activated delayed fluorescence emission energy can be obtained from the wavelength of an emission peak (including a shoulder) on the shortest wavelength side of the thermally activated delayed fluorescence.

[0034] It should be noted that in this description and similar texts, "room temperature" refers to a temperature higher than or equal to 0 °C and lower than or equal to 40 °C.

[0035] In this description and similar usage, a wavelength range of blue refers to a wavelength range greater than or equal to 400 nm and less than 505 nm, and blue light exhibits at least one peak in an emission spectrum within this range. A wavelength range of green refers to a wavelength range greater than or equal to 505 nm and less than 580 nm, and green light exhibits at least one peak in an emission spectrum within this range. A wavelength range of red refers to a wavelength range greater than or equal to 580 nm and less than or equal to 680 nm, and red light exhibits at least one peak in an emission spectrum within this range. (Version 1)

[0036] In this embodiment, a light-emitting element of an embodiment of the present invention is described below based on Fig. 1A and Fig. 1B as well as Fig. 2A and Fig. 2B described. <Strukturbeispiel des Licht emittierenden Elements>

[0037] First, a structure of the light-emitting element of an embodiment of the present invention is described based on Fig. 1A and Fig. 1B described.

[0038] Fig. Figure 1A is a schematic cross-sectional view of a light-emitting element 150 of an embodiment of the present invention.

[0039] The light-emitting element 150 comprises a pair of electrodes (an electrode 101 and an electrode 102) and an EL layer 100 between the pair of electrodes. The EL layer 100 comprises at least one light-emitting layer 130.

[0040] The EL layer 100, which is in Fig. Figure 1A shows that, in addition to the light-emitting layer, 130 functional layers are included, such as a hole injection layer 111, a hole transport layer 112, an electron transport layer 118 and an electron injection layer 119.

[0041] Although this embodiment is described assuming that electrode 101 and electrode 102 of the electrode pair serve as the anode and cathode, respectively, the structure of the light-emitting element 150 is not limited to this. That is to say, electrode 101 can be a cathode, electrode 102 can be an anode, and the arrangement of the layers between the electrodes can be reversed. In other words, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 130, the electron transport layer 118, and the electron injection layer 119 can be arranged in this order, starting from the anode side.

[0042] The structure of EL layer 100 is not based on the structure found in Fig. Figure 1A is limited, and a structure comprising at least one layer selected from the hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119 can be used. Alternatively, the EL layer 100 can, for example, comprise a functional layer suitable for lowering a hole or electron injection barrier, improving a hole or electron transport property, preventing hole or electron transport, or suppressing an electrode quenching effect. It should be noted that the functional layers can each be a single layer or a multiple layer.

[0043] Fig. Figure 1B is a schematic cross-sectional view showing an example of the light-emitting layer 130 in Fig. 1A represents the light-emitting layer 130 in Fig. 1B contains a host material 131 and a guest material 132. The host material 131 contains an organic compound 131_1 and an organic compound 131_2.

[0044] The guest material 132 can be a light-emitting organic material, and the light-emitting organic material is preferably a material suitable for emitting phosphorescence (hereinafter also referred to as the phosphorescent material). A structure in which a phosphorescent material is used as the guest material 132 is described below. The guest material 132 can also be reformulated as a phosphorescent material. <Lichtemissionsmechanismus des Licht emittierenden Elements>

[0045] Next, the light emission mechanism of the light-emitting layer 130 will be described.

[0046] The organic compound 131_1 and the organic compound 131_2, which are contained in the host material 131 in the light-emitting layer 130, form an exciplex.

[0047] As long as the combination of organic compound 131_1 and organic compound 131_2 can form an exciplex, it is acceptable; however, preferably one of them is a compound with a hole-transporting function (a hole-transporting property) and the other is a compound with an electron-transporting function (an electron-transporting property). In this case, a donor-acceptor exciplex is readily formed; thus, an exciplex can be formed efficiently.

[0048] The combination of organic compound 131_1 and organic compound 131_2 is preferably as follows: One compound has a lower HOMO (highest occupied molecular orbital) level and a lower LUMO (lowest unoccupied molecular orbital) level than the other.

[0049] In the case where, for example, organic compound 131_1 has an electron transport property and organic compound 131_2 has a hole transport property, the HOMO level of organic compound 131_1 is preferably lower than that of organic compound 131_2, and the LUMO level of organic compound 131_1 is preferably lower than that of organic compound 131_2, as shown in the energy band diagram in Fig. 2A shown.

[0050] At this time, an exciplex formed by organic compound 131_1 and organic compound 131_2 has an excitation energy approximately equal to an energy difference (ΔE). Ex ) between the LUMO level of organic compound 131_1 and the HOMO level of organic compound 131_2.

[0051] A difference between the HOMO level of organic compound 131_1 and that of organic compound 131_2 is preferably greater than or equal to 0.1 eV, more preferably greater than or equal to 0.2 eV. A difference between the LUMO level of organic compound 131_1 and that of organic compound 131_2 is preferably greater than or equal to 0.1 eV, more preferably greater than or equal to 0.2 eV. The energy difference is preferred because it promotes the injection of electron and hole charge carriers from the pair of electrodes (electrode 101 and electrode 102) into organic compound 131_1 and organic compound 131_2.

[0052] It should be noted that in Fig. 2A Host (131_1) represents the organic compound 131_1, Host (131_2) represents the organic compound 131_2, Guest (132) represents the guest material 132, ΔE Exrepresents an energy difference between the LUMO level of organic compound 131_1 and the HOMO level of organic compound 131_2, ΔE B represents an energy difference between the LUMO level of the organic compound 131_1 and the HOMO level of the guest material 132, as well as ΔE G represents an energy difference between the LUMO level and the HOMO level of the guest material 132.

[0053] To cause the guest material 132 to emit light of a short wavelength with a high emission energy, the following applies: The greater the energy difference (ΔE) GThe smaller the energy difference (ΔE) between the LUMO level and the HOMO level of the guest material 132, the better. However, the excitation energy in the light-emitting element 150 is preferably as small as possible to reduce the drive voltage; therefore, the following applies: The smaller the excitation energy of an exciplex formed by the organic compounds 131_1 and 131_2, the better. Consequently, the energy difference (ΔE) Ex ) between the LUMO level of organic compound 131_1 and the HOMO level of organic compound 131_2 is preferably small.

[0054] Guest material 132 is a phosphorescent light-emitting material and thus possesses a function for converting triplet excitation energy into light emission. Furthermore, energy in a triplet excitation state is more stable than in a singlet excitation state. Consequently, guest material 132 can emit light with an energy that is smaller than the energy difference (ΔE). G ) between the LUMO level and the HOMO level of the guest material 132. The inventors of the present invention have found that even in the case where the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 132 is greater than the energy difference (ΔE) Ex) between the LUMO level of organic compound 131_1 and the HOMO level of organic compound 131_2, the excitation energy transfer from an exciplex formed by organic compound 131_1 and organic compound 131_2 to the guest material 132 is possible and light emission from the guest material 132 can be obtained as long as a light emission energy (ΔE) Em ) of the guest material 132 or a transition energy (ΔE abs ), which is calculated from an absorption edge of an absorption spectrum, less than or equal to ΔE Ex is. If ΔE G of the guest material 132 greater than the energy (ΔE Em ) the light emission from the guest material 132 or the transition energy (ΔE abs ) is, which is calculated from the absorption edge of the absorption spectrum, is a high electrical energy, which ΔE GThis corresponds to the necessary voltage to directly bring about an electrical excitation of the guest material 132, thereby increasing the drive voltage of a light-emitting element. However, in one embodiment of the present invention, an exciplex is electrically excited with an electrical energy that ΔE Ex corresponds to (which is smaller than ΔE) G is excited), and the guest material 132 is excited by energy transfer from the exciplex, so that light emission from the guest material 132 can be obtained very efficiently with a low drive voltage. That is to say, an embodiment of the present invention is particularly useful in the case where ΔE G significantly larger than the energy (ΔE) Em ) the light emission from the guest material 132 or the transition energy (ΔE abs ) is calculated from the absorption spectrum (for example, in the case where the guest material is a material that emits blue light).

[0055] In the case where the guest material 132 contains a heavy metal, intersystem crossing between a singlet state and a triplet state is promoted by a spin-orbit interaction (an interaction between the spin angular momentum and the orbital angular momentum of an electron), and a transition between a singlet ground state and a triplet excitation state of the guest material 132 is not forbidden in some cases. Consequently, the emission efficiency and absorption probability relating to the transition between the singlet ground state and the triplet excitation state of the guest material 132 can be increased. Accordingly, the guest material 132 preferably contains a metallic element with a large spin-orbit interaction, in particular a platinum group element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt)).Iridium is particularly preferred because it can increase the absorption probability, which concerns the direct transition between a singlet ground state and a triplet excited state.

[0056] In order for the guest material 132 to emit light with a high luminous emission energy (light of a short wavelength), the lowest triplet excitation energy level of the guest material 132 is preferably high. To ensure that the lowest triplet excitation energy level of the guest material 132 is high, the ligand coordinated to the heavy metal atom of the guest material 132 preferably has a high lowest triplet excitation energy level, low electron acceptor properties, and a high LUMO level.

[0057] Such a guest material tends to exhibit a molecular structure with a high HOMO level and high hole-accepting properties. If the guest material 132 has a molecular structure with high hole-accepting properties, the HOMO level of the guest material 132 is sometimes higher than that of the organic compound 131_2. Furthermore, if ΔE G is greater than ΔE H The LUMO level of guest material 132 is higher than the LUMO level of organic compound 131_1. It should be noted that the energy difference between the LUMO level of guest material 132 and the LUMO level of organic compound 131_1 is greater than the energy difference between the HOMO level of guest material 132 and the HOMO level of organic compound 131_2.

[0058] If the HOMO level of the guest material 132 is higher than that of the organic compound 131_2 and the LUMO level of the guest material 132 is higher than that of the organic compound 131_1, then, among charge carriers (holes and electrons) injected by the pair of electrodes (electrode 101 and electrode 102), holes injected from the anode are readily injected into the guest material 132 and electrons injected from the cathode are readily injected into the organic compound 131_1 in the light-emitting layer 130. Therefore, it is possible that the organic compound 131_1 and the guest material 132 form an exciplex if the guest material 132 has the highest HOMO level and the organic compound 131_1 the lowest LUMO level among the materials of the light-emitting layer 130. In particular, if there is an energy difference (ΔE) B) between the LUMO level of the organic compound 131_1 and the HOMO level of the guest material 132 is smaller than the emission energy of the guest material (ΔE) Em The generation of exciplexes formed by the organic compound 131_1 and the guest material 132 becomes predominant. In this case, it is difficult for an excitation state to be formed solely by the guest material 132, which reduces the emission efficiency of the light-emitting element.

[0059] It should be noted that the reactions described above can be represented by formula (G11) or (G12). A−+G−→(A⋅G)* A+G*→(A⋅G)*

[0060] Formula (G11) represents a reaction in which the organic compound 131_1 loses an electron (A - ) records and the guest material 132 a hole (G +The formula (G12) represents a reaction in which the guest material 132 (G*) in the excited state interacts with the organic compound 131_1 (A) in the ground state, thereby forming an exciplex ((A·G)*). The formation of the exciplex ((A·G)*) by the organic compound 131_1 and the guest material 132 makes it more difficult for the guest material 132 alone to form an excited state (G*).

[0061] An exciplex formed by the organic compound 131_1 and the guest material 132 has an excitation energy that is approximately equal to the energy difference (ΔE). B ) between the LUMO level of the organic compound 131_1 and the HOMO level of the guest material 132. The inventors of the present invention have found that when an energy difference (ΔE)B ) between the LUMO level of the organic compound 131_1 and the HOMO level of the guest material 132 greater than or equal to an emission energy (ΔE) Em ) of the guest material 132 or a transition energy (ΔE abs ) is, which is calculated from the absorption edge of the absorption spectrum of the guest material 132, the reaction to form an exciplex by the organic compound 131_1 and the guest material 132 can be prevented, which can result in a high emission efficiency of the guest material 132. Since ΔE abs smaller than ΔE B The guest material 132 readily receives excitation energy. Excitation of the guest material 132 by receiving the excitation energy requires less energy and provides a more stable excited state than the formation of an exciplex by the organic compound 131_1 and the guest material 132.

[0062] As described above, even if the energy difference (ΔE) G ) between the LUMO level and the HOMO level of the guest material 132 is greater than the energy difference (ΔE) Ex ) between the LUMO level of organic compound 131_1 and the HOMO level of organic compound 131_2, an excitation energy is efficiently transferred from an exciplex formed by organic compound 131_1 and organic compound 131_2 to the guest material 132, as long as the transition energy (ΔE abs ), which is calculated from an absorption edge of an absorption spectrum of the guest material 132, less than or equal to ΔE Ex As a result, a light-emitting element with high efficiency and a low drive voltage can be obtained, which is a feature of an embodiment of the present invention. At this point, the formula ΔE abs ≤ ΔEEx < ΔE G (ΔE abs is less than or equal to ΔE Ex and ΔE Ex is smaller than ΔE G ) fulfilled. Therefore, the mechanism of an embodiment of the present invention is suitable in the case where ΔE abs is smaller than ΔE G In other words, the mechanism of an embodiment of the present invention is suitable in the case where ΔE G is greater than ΔE abs In particular, the energy difference (ΔE) G ) between the LUMO level and the HOMO level of the guest material 132 preferably by 0.3 eV or more, more preferably by 0.4 eV or more, greater than the transition energy (ΔE) abs ), which is calculated from the absorption edge of the absorption spectrum of guest material 132. Since the light emission energy (ΔE Em ) of the guest material 132 less than or equal to ΔE abs is the energy difference (ΔE G) between the LUMO level and the HOMO level of the guest material 132 preferably by 0.3 eV or more, more preferably by 0.4 eV or more greater than the light emission energy (ΔE) Em ) of the guest material 132. It should be noted that the light emission energy (ΔE Em ) can be derived from the wavelength of an emission peak (the maximum value or including a shoulder) on the shortest wavelength side of the emission spectrum.

[0063] Preferably, ΔE abs ≤ ΔE B (ΔE abs is less than or equal to ΔE B ) or ΔE Em ≤ ΔE B (ΔE Em is less than or equal to ΔE B ) fulfills the conditions described above if the HOMO level of the guest material 132 is higher than that of the organic compound 131_2. Therefore, ΔE is preferably abs ≤ ΔE B < ΔE Ex < ΔE G (ΔE abs is less than or equal to ΔEB , ΔE B is smaller than ΔE Ex as well as ΔE Ex is smaller than ΔE G ) or ΔE Em ≤ ΔE B < ΔE Ex < ΔE G (ΔE Em is less than or equal to ΔE B , ΔE B is smaller than ΔE Ex as well as ΔE Ex is smaller than ΔE G ) fulfilled. The foregoing conditions represent important discoveries of an embodiment of the present invention.

[0064] The shorter the emission wavelength of the guest material 132 and the higher the light emission energy (ΔE) Em ), the greater the energy difference (ΔE) G ) between the LUMO level and the HOMO level of the guest material 132; consequently, a greater energy is required for the electrical excitation of the guest material 132. However, if, according to one embodiment of the present invention, the transition energy (ΔE abs), which is calculated from the absorption edge of the absorption spectrum of the guest material 132, less than or equal to ΔE Ex is that the guest material 132 is excited with an energy as small as ΔE Ex is what is smaller than ΔE G This reduces the power consumption of the light-emitting element. Consequently, the effect of the mechanism in one embodiment of the present invention becomes effective when there is an energy difference between the transition energy (ΔE). abs ), which is calculated from the absorption edge of the absorption spectrum of the guest material 132, and the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material is 132 (i.e., especially in the case where the guest material is a material that emits blue light).

[0065] If the transition energy (ΔE) absIf the ΔE, calculated from the absorption edge of the absorption spectrum of guest material 132, decreases, the light emission energy of guest material 132 also decreases. In this case, light emission requiring high energy, such as blue light emission, is difficult to obtain. That is: If there is a difference between ΔE abs and ΔE G If the size is too large, it is difficult to obtain high-energy light emission, such as blue light emission.

[0066] For these reasons, the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 132 preferably by 0.3 eV to 0.8 eV, more preferably by 0.4 eV to 0.8 eV, and even more preferably by 0.5 eV to 0.8 eV greater than the transition energy (ΔE) abs ), which is calculated from the absorption edge of the absorption spectrum of guest material 132. Since the light emission energy (ΔE Em) of the guest material 132 less than or equal to ΔE abs is the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 132 preferably by 0.3 eV to 0.8 eV, more preferably by 0.4 eV to 0.8 eV, and even more preferably by 0.5 eV to 0.8 eV greater than the light emission energy (ΔE) Em ) of the guest material 132.

[0067] A difference between the HOMO level of the guest material 132 and the HOMO level of the organic compound 131_2 is preferably greater than or equal to 0.05 eV and less than or equal to 0.4 eV. This is because adequate hole trapping leads to a longer lifetime of a light-emitting element, whereas an excessively high HOMO level of the guest material ΔE BThe difference between the LUMO level of the guest material 132 and the LUMO level of the organic compound 131_1 is preferably greater than or equal to 0.05 eV, more preferably greater than or equal to 0.1 eV, and even more preferably greater than or equal to 0.2 eV. This is because electron charge carriers with such a correlation of energy levels are easily injected into the organic compound 131_1.

[0068] Since the energy difference (ΔE ExIf the energy difference between the LUMO level of organic compound 131_1 and the HOMO level of organic compound 131_2 is smaller than the energy difference between the LUMO level and the HOMO level of organic compound 131_1 and smaller than the energy difference between the LUMO level and the HOMO level of organic compound 131_2, then the formation of an exciplex by organic compound 131_1 and organic compound 131_2 is energetically more stable than the formation of an excited state by either organic compound 131_1 or organic compound 131_2 alone. Furthermore, if the energy difference (ΔE) G ) between the LUMO level and the HOMO level of the guest material 132 is greater than the energy difference (ΔE) Ex) between the LUMO level of organic compound 131_1 and the HOMO level of organic compound 131_2, the formation of an exciplex by organic compound 131_1 and organic compound 131_2 is energetically more stable than an excitation state formed by recombination of charge carriers (holes and electrons) injected into the light-emitting layer 130. Consequently, the majority of the excitation states generated in the light-emitting layer 130 are present as exciplexes formed by organic compound 131_1 and organic compound 131_2. Accordingly, the structure of one embodiment of the present invention facilitates the transfer of excitation energy from the exciplex to the guest material 132, resulting in a lower drive voltage of the light-emitting element and a higher emission efficiency.

[0069] It should be noted that the LUMO level of guest material 132 may be higher or lower than the LUMO level of organic compound 131_2.

[0070] Furthermore, the guest material 132 acts as a hole trap in the light-emitting layer 130, since its HOMO level is higher than that of the organic compound 131_1. This is advantageous because the charge carrier balance in the light-emitting layer can be easily controlled thanks to the guest material 132 acting as a hole trap, resulting in a longer lifetime.

[0071] In the case where the combination of organic compounds 131_1 and 131_2 is a combination of a compound with hole transport properties and a compound with electron transport properties, the charge carrier balance can be easily controlled depending on the mixing ratio. In particular, the weight ratio of the compound with hole transport properties to the compound with electron transport properties is preferably within a range of 1:9 to 9:1. Since the charge carrier balance can be easily controlled by the structure, a charge carrier recombination range can also be easily controlled.

[0072] The exciplex formed by organic compounds 131_1 and 131_2 has the HOMO in one of the organic compounds and the LUMO in the other; thus, the overlap between the HOMO and the LUMO is very small. This means that the difference between a singlet excitation energy level and a triplet excitation energy level in the exciplex is small. The difference between the triplet excitation energy level and the singlet excitation energy level of the exciplex formed by organic compounds 131_1 and 131_2 is therefore preferably greater than 0 eV and less than or equal to 0.2 eV, and more preferably greater than 0 eV and less than or equal to 0.1 eV.

[0073] Fig. Figure 2B shows a correlation of energy levels of organic compound 131_1, organic compound 131_2, and guest material 132 in the light-emitting layer 130. The following clarifies what terms and symbols in Fig. 2B: Host (131_1): a host material (the organic compound 131_1); Host (131_2): a host material (the organic compound 131_2); Guest (132): the guest material 132 (the phosphorescent material); Exciplex: an Exciplex (organic compound 131_1 and organic compound 131_2); S PH1 : the S1 level of the host material (of the organic compound 131_1); T PH1 : the T1 level of the host material (of the organic compound 131_1); S PH2 : the S1 level of the host material (of the organic compound 131_2); T PH2 : the T1 level of the host material (of the organic compound 131_2); S PG : the S1 level of the guest material 132 (the phosphorescent material); T PG : the T1 level of the guest material 132 (the phosphorescent material); S PE : the S1 level of the exciplex; and T PE : the T1 level of the exciplex.

[0074] In the light-emitting element of an embodiment of the present invention, the organic compounds 131_1 and 131_2, which are contained in the light-emitting layer 130, form an exciplex. The S1 level of the exciplex (S PE ) and the T1 level of the exciplex (T PE ) are next to each other (see Route E7 in Fig. 2B).

[0075] An exciplex is an excited state formed by two types of substances. In the case of light excitation, the exciplex is formed by the interaction between one substance in an excited state and the other substance in a ground state. The two types of substances that formed the exciplex return to a ground state by emitting light, and they once again function as the two original types of substances. In the case of electrical excitation, when one substance is brought into an excited state, it immediately interacts with the other substance to form an exciplex. Alternatively, one substance receives a hole and the other substance receives an electron, readily forming an exciplex.In this case, any of the substances can form an exciplex without themselves forming an excited state, and consequently, the majority of the excited states formed in the light-emitting layer 130 can exist as exciplexes. Since the excitation energy levels (p. E and T E ) of the exciplex are lower than the S1 levels (S PH1 and S PH2 By reducing the energy of the host materials (organic compound 131_1 and organic compound 131_2) that form the exciplex, the excited state of host material 131 can be established with a lower excitation energy. Accordingly, the drive voltage of the light-emitting element 150 can be reduced.

[0076] Both energies, S PE and T PE , the exciplexes are then reduced to the T1 level (T PG) of the guest material 132 (the phosphorescent material) is transferred; thus, a light emission is obtained (see routes E8 and E9 in Fig. 2B).

[0077] Furthermore, the T1 level (T PE ) of the exciplex preferably higher than the T1 level (T PG ) of the guest material 132. If the T1 levels satisfy such a relationship, the singlet excitation energy and the triplet excitation energy of the formed exciplex can be determined from the S1 level (S PE ) and the T1 level (T PE ) of the exciplex to the T1 level (T PG ) of the guest material 132 will be transferred.

[0078] If the light-emitting layer 130 has the structure described above, light emission from the guest material 132 (the phosphorescent material) of the light-emitting layer 130 can be obtained efficiently.

[0079] In this description and similar descriptions, the processes described above via routes E7, E8, and E9 can be referred to as exciplex triplet energy transfer (ExTET). In other words, in the light-emitting layer 130, excitation energy is transferred from the exciplex to the guest material 132. In this case, the efficiency of the reverse intersystem crossing of T must be considered. PE on S PE not necessarily be high and the emission quantum yield of S PE It also does not necessarily have to be high, which allows for a wide range of material options to be selected.

[0080] It should be noted that the reactions described above can be represented by formulas (G13) to (G15). D++A−→(D⋅A)* (D⋅A)*+ G→D+A+G* G*→G+hv

[0081] In formula (G13), either organic compound 131_1 or organic compound 131_2 occupies a hole (D + ) and the other accepts an electron (A - ) whereby organic compound 131_1 and organic compound 131_2 form an exciplex ((D·A)*). In formula (G14), energy is transferred from the exciplex ((D·A)*) to the guest material 132 (G), thereby creating an excited state of the guest material 132 (G*). Subsequently, as shown by formula (G15), the guest material 132 emits light (hv) in the excited state.

[0082] It should be noted that, in order to efficiently transfer excitation energy from the exciplex to the guest material 132, the T1 level (T PEThe T1 level of the exciplex is preferably lower than the T1 levels of the organic compounds (organic compound 131_1 and organic compound 131_2) in the host material that form the exciplex. Consequently, the probability of quenching the triplet excitation energy of the exciplex due to the organic compounds is lower, leading to efficient energy transfer to the guest material 132.

[0083] If organic compound 131_2 comprises a framework with strong donor properties, a hole injected into the light-emitting layer 130 is readily injected into and transported to organic compound 131_2. If organic compound 131_1 comprises a framework with strong acceptor properties, an electron injected into the light-emitting layer 130 is readily injected into and transported to organic compound 131_1. When electrons and holes are injected into organic compound 131_1 and organic compound 131_2, respectively, organic compound 131_1 and organic compound 131_2 readily form an exciplex.

[0084] If the light-emitting layer 130 has the structure described above, light emission from the guest material 132 of the light-emitting layer 130 can be obtained efficiently. <Energieübertragungsmechanismus>

[0085] Next, factors controlling the processes of intermolecular energy transfer between host material 131 and guest material 132 are described. Two mechanisms have been proposed for intermolecular energy transfer: the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange interaction). Here, the intermolecular energy transfer process between host material 131 and guest material 132 is described; however, the same applies to the case where host material 131 is an exciplex. <<Förster-Mechanismus> >

[0086] In the Förster mechanism, energy transfer does not require direct contact between molecules, and energy is transferred via a resonance phenomenon of a dipole vibration between the host material 131 and the guest material 132. Through this resonance phenomenon, the host material 131 releases energy to the guest material 132, thus bringing the excited host material 131 to a ground state, and the ground-state guest material 132 to an excited state. It should be noted that the rate constant k h*→g The Förster mechanism is represented by formula (1). [Formula 1] kh*→g=9000c4K2ϕ ln 10128π5n4N τR6∫f'h(v)εg(v)v4dv

[0087] In formula (1), v represents a frequency, f' h(v) represents a normalized emission spectrum of the host material 131 (a fluorescence spectrum upon energy transfer from a singlet excitation state, and a phosphorescence spectrum upon energy transfer from a triplet excitation state), ε g (v) represents a molar absorption coefficient of the guest material 132, N represents Avogadro's number, n represents a refractive index of a medium, R represents an intermolecular distance between the host material 131 and the guest material 132, τ represents a measured lifetime of an excitation state (fluorescence lifetime or phosphorescence lifetime), c represents the speed of light, ϕ represents a luminescence quantum yield (a fluorescence quantum yield for energy transfer from a singlet excitation state, and a phosphorescence quantum yield for energy transfer from a triplet excitation state), and K 2represents a coefficient (0 to 4) depending on the orientation of a transition dipole moment of the host material 131 and that of a transition dipole moment of the guest material 132. It should be noted that with random orientation K 2 2 / 3. < <dexter-mechanismus>>

[0088] In the Dexter mechanism, the host material 131 and the guest material 132 are located within a contact-effective region where their orbitals overlap, and the host material 131, which is in an excited state, and the guest material 132, which is in a ground state, exchange electrons, resulting in an energy transfer. It should be noted that the rate constant k h*→g the Dexter mechanism is represented by formula (2). [Formula 2] kh*→g=(2πh)K2exp(−2RL)∫f'h(v)ε'g(v)dv

[0089] In formula (2), h represents a Planck constant, K represents a constant with an energy dimension, v represents a frequency, f' h (v) represents a normalized emission spectrum of the host material 131 (a fluorescence spectrum upon energy transfer from a singlet excitation state, and a phosphorescence spectrum upon energy transfer from a triplet excitation state), ε' g (v) represents a normalized absorption spectrum of the guest material 132, L represents an effective molecular radius and R represents an intermolecular distance between the host material 131 and the guest material 132.

[0090] Here, the efficiency of energy transfer from the host material 131 to the guest material 132 (energy transfer efficiency ϕ) is measured. ET ) is represented by formula (3). In the formula, k represents r a rate constant of a light emission process (fluorescence upon energy transfer from a singlet excitation state, and phosphorescence upon energy transfer from a triplet excitation state) of the host material 131, k n represents a rate constant of a process without light emission (thermal deactivation or intersystem crossing) of the host material 131, and τ represents a measured lifetime of an excitation state of the host material 131. [Formula 3] ϕET=kh*→gkr+kn+kh*→g=Kh*→g(1τ)+kh*→g

[0091] According to formula (3) it has been found that the energy transfer efficiency ϕ ET by increasing the velocity constant k h*→g during energy transfer, so that another competing velocity constant k r + k n (= 1 / τ) becomes relatively small. <<Konzept zur Förderung der Energieübertragung> >

[0092] Energy transfer via the Förster mechanism results in a high energy transfer efficiency ϕ. ET A high quantum yield ϕ (the fluorescence quantum yield in the case of energy transfer from a singlet excitation state, and the phosphorescence quantum yield in the case of energy transfer from a triplet excitation state) is obtained. Furthermore, the emission spectrum (the fluorescence spectrum in the case of energy transfer from the singlet excitation state) of the host material 131 preferably exhibits a large overlap with the absorption spectrum (absorption corresponding to the transition from the singlet ground state to the triplet excitation state) of the guest material 132. It is also preferred that the molar absorption coefficient of the guest material 132 is high. This means that the emission spectrum of the host material 131 overlaps the absorption band of the absorption spectrum of the guest material 132, which is located on the longest wavelength side.

[0093] To determine the velocity constant k h*→g To increase energy transfer via the Dexter mechanism, the emission spectrum (a fluorescence spectrum in the case of energy transfer from a singlet excitation state, and a phosphorescence spectrum in the case of energy transfer from a triplet excitation state) of the host material 131 preferably exhibits a large overlap with the absorption spectrum (absorption corresponding to the transition from a singlet ground state to a triplet excitation state) of the guest material 132. Consequently, the energy transfer efficiency can be optimized by ensuring that the emission spectrum of the host material 131 overlaps the absorption band of the absorption spectrum of the guest material 132 that lies on the longest wavelength side.

[0094] In a manner similar to that of energy transfer from host material 131 to guest material 132, energy transfer through the Förster mechanism and through the Dexter mechanism also occurs in the energy transfer process from the exciplex to guest material 132.

[0095] Accordingly, one embodiment of the present invention provides a light-emitting element which, as host material 131, contains the organic compounds 131_1 and 131_2, which together form an exciplex that acts as an energy donor capable of efficiently transferring energy to the guest material 132. The excitation energy required to form the exciplex by organic compounds 131_1 and 131_2 can be lower than the excitation energy of organic compound 131_1 in the excited state and lower than the excitation energy of organic compound 131_2 in the excited state. Thus, the drive voltage of the light-emitting element 150 can be reduced.To promote energy transfer from the singlet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 132, which functions as an energy acceptor, the emission spectrum of the exciplex preferably overlaps the absorption band of the absorbance spectrum of the guest material 132, which is located on the longest wavelength side (lowest energy side). Such emission and absorption spectra increase the efficiency of generating the triplet excitation state of the guest material 132. The exciplex generated in the light-emitting layer 130 has the following feature: its singlet excitation energy level is close to the triplet excitation energy level.Therefore, by overlapping the emission spectrum of the exciplex and the absorption band of the absorption spectrum of the guest material 132, which is located on the longest wavelength side (lowest energy side), the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 132 can be promoted. <material>

[0096] Next, the components of a light-emitting element of an embodiment of the present invention will be described in detail. <<Licht emittierende Schicht> >

[0097] In the light-emitting layer 130, the host material 131 is present in the highest weight fraction, and the guest material 132 (the phosphorescent material) is dispersed in the host material 131. The T1 level of the host material 131 (organic compound 131_1 and organic compound 131_2) in the light-emitting layer 130 is preferably higher than the T1 level of the guest material (guest material 132) in the light-emitting layer 130. < <wirtsmaterial>>

[0098] Organic compound 131_1 can be a material that has the property of transporting more electrons than holes, wherein a material has an electron mobility of 1 × 10 -6 cm 2 / Vs or higher is preferable. According to the present invention, a compound comprising a triazine backbone is used.

[0099] Specific examples include heterocyclic compounds with a triazine framework, such as 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn). Among heterocyclic compounds, those with a triazine framework are highly reliable. Furthermore, these heterocyclic compounds exhibit high electron transport properties, which contribute to a reduction in the drive voltage.

[0100] Organic compound 131_2 is preferably a substance that can form an exciplex together with organic compound 131_1. In particular, organic compound 131_2 preferably comprises a framework with high donor properties, such as a framework with a π-electron-rich heteroaromatic ring or an aromatic amine framework. Examples of the compound comprising a framework with a π-electron-rich heteroaromatic ring include heteroaromatic compounds such as a dibenzothiophene derivative, a dibenzofuran derivative, and a carbazole derivative.Preferably, in this case, organic compound 131_1, organic compound 131_2, and guest material 132 (the phosphorescent material) are selected such that the emission peak of the exciplex formed by organic compound 131_1 and organic compound 131_2 overlaps an absorption band, in particular an absorption band on the longest wavelength side, of a triplet metal-to-ligand charge transfer (MLCT) transition of guest material 132 (the phosphorescent material). This makes it possible to provide a light-emitting element with a drastically improved emission efficiency. It should be noted that if a thermally activated delayed-fluorescence material is used instead of the phosphorescent material, the absorption band on the longest wavelength side is preferably a singlet absorption band.

[0101] The following materials with hole transport properties can be used as organic compound 131_2.

[0102] A material that has the property of transporting more holes than electrons can be used as a hole transport material, where a material with a hole mobility of 1 × 10 -6 cm 2 / Vs or higher is preferable. In particular, an aromatic amine, a carbazole derivative, an aromatic hydrocarbon, a stilbene derivative, or the like can be used. Furthermore, the hole transport material can be a high-molecular-weight compound.

[0103] Examples of aromatic amine compounds that can be used as materials with high hole transport properties are 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), 1,3,5-Tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B) and the like.

[0104] Specific examples of the carbazole derivative are 3-[N-(4-Diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-Bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 3-[N-(9-Phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-Bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-Naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) and the like.

[0105] Other examples of the carbazole derivative are 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.

[0106] Examples of the aromatic hydrocarbon are 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-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 and the like. Other examples include pentacene, coronene, and the like.The aromatic hydrocarbon, which has a hole mobility of 1 × 10. -6 cm 2 A carbon atom with a carbon density of / Vs or higher and more than or equal to 14 and less than or equal to 42 carbon atoms is particularly preferred.

[0107] The aromatic hydrocarbon may contain a vinyl skeleton. Examples of aromatic hydrocarbons with a vinyl group are 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA), and the like.

[0108] Other examples include high-molecular-weight compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), Poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide ] (abbreviation: PTPDMA) and Poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (Abbreviation: Poly-TPD).

[0109] Examples of materials with high hole transport properties are aromatic amine compounds, such as... B. 4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-Bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4"-Tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), 4,4',4"-Tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), 4,4',4"-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4"-Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 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), N-(9,9-Dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-Dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-Diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 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) 4-Phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N'-Bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N,N'-Triphenyl-N,N,N'-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-Biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,1'-Biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 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), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP) and N,N-Bis[4-(carbazol-9-yl)phenyl]-N,N-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F). Other examples include amine compounds, carbazole compounds, thiophene compounds, furan compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds, and the like, such as 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-Bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-Bis(N-carbazolyl)benzene (abbreviation: mCP), 3,6-Bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,6-Di(9H-carbazol-9-yl)-9-phenyl-9H-carbazole (abbreviation: PhCzGI), 2,8-Di(9H-carbazol-9-yl)-dibenzothiophene (abbreviation: Cz2DBT), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl} dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4',4"-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-Tri(dibenzothiophene-4-yl)benzene (abbreviation: DBT3P-II), 2,8-Diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (Abbreviation: DBTFLP-III), 4-[4-(9-Phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV) and 4-[3-(Triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II). Among the above compounds, those comprising a pyrrole framework, a furan framework, a thiophene framework, or an aromatic amine framework are preferred due to their high stability and reliability. Furthermore, compounds with such frameworks exhibit high hole transport properties.which contributes to a reduction in the drive voltage. < <gastmaterial>>

[0110] The guest material 132 (phosphorescent material) can be an iridium-, rhodium-, or platinum-based organometallic complex or metal complex; in particular, an organoiridium complex, such as an iridium-based orthometallated complex, is preferred. The orthometallated ligand can be a 4H-triazole ligand, a 1H-triazole ligand, an imidazole ligand, a pyridine ligand, a pyrimidine ligand, a pyrazine ligand, an isoquinoline ligand, and the like. The metal complex can be a platinum complex with a porphyrin ligand, and the like.

[0111] Organic compound 131_1, organic compound 131_2, and guest material 132 (phosphorescent material) are preferably selected such that the LUMO level of guest material 132 (the phosphorescent material) is higher than that of organic compound 131_1 and that the HOMO level of guest material 132 is higher than that of organic compound 131_2. With this structure, a light-emitting element with high emission efficiency and a low drive voltage can be obtained.

[0112] Examples of the substance exhibiting an emission peak in the blue or green wavelength range include organometallic iridium complexes with a 4H-triazole framework, such as... B. Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}i ridium(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) and Tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (Abbreviation: Ir(iPr5btz)3); organometallic iridium complexes with a 1H-triazole skeleton, such as Tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(Mptz1-mp)3) and Tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (Abbreviation: Ir(Prptz1-Me)3); organometallic iridium complexes with an imidazole skeleton, such as fac-Tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: Ir(iPrpmi)3) and Tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (Abbreviation: Ir(dmpimpt-Me)3); and organometallic iridium complexes in which a phenylpyridine derivative with an electron-withdrawing group is a ligand, such as Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III)tetrakis(1-pyrazolyl)borate (abbreviation: Flr6), Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III)picolinate (abbreviation: Flrpic), Bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2' }iridium(III)picolinate (abbreviation: Ir(CF3ppy)2(pic)) and Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]Iridium(III)acetylacetonate (abbreviation: Flr(acac)). Among the materials mentioned above, the organometallic iridium complexes comprising a five-membered nitrogenous heterocyclic framework, such as a 4H-triazole framework, a 1H-triazole framework, or an imidazole framework, exhibit high triplet excitation energy, reliability, and emission efficiency and are therefore particularly preferred.

[0113] Examples of substances exhibiting an emission peak in the green or yellow wavelength range include organometallic iridium complexes with a pyrimidine backbone, such as 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[4-(2-norbornyl)-6-phenylpyrimidinato]iridium(III) (Abbreviation: Ir(nbppm)2(acac)), (Acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (Abbreviation: Ir(mpmppm)2(acac)), (Acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κ C}iridium(III) (abbreviation: Ir(dmppm-dmp)2(acac)) and (Acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: Ir(dppm)2(acac)); organometallic iridium complexes with a pyrazine framework, such as (Acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir(mppr-Me)2(acac)) and (Acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir(mppr-iPr)2(acac)); organometallic iridium complexes with a pyridine skeleton, such as Tris(2-phenylpyridinato-N,C 2' )iridium(III) (abbreviation: Ir(ppy)3), Bis(2-phenylpyridinato-N,C 2' )iridium(III)acetylacetonate (abbreviation: Ir(ppy)2(acac)), Bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: Ir(bzq)2(acac)), Tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq)3), Tris(2-phenylquinolinato-N,C 2' )iridium(III) (abbreviation: Ir(pq)3) and bis(2-phenylquinolinato-N,C 2' )iridium(III)acetylacetonate (abbreviation: Ir(pq)2(acac)); organometallic iridium complexes, such as bis(2,4-diphenyl-1,3-oxazolato-N,C 2' )iridium(III)acetylacetonate (abbreviation: Ir(dpo)2(acac)),

[0114] Bis{2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2' }iridium(III)acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)) and bis(2-phenylbenzothiazolato-N,C 2' )iridium(III)acetylacetonate (abbreviation: Ir(bt)2(acac)); and a rare-earth metal complex, such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: Tb(acac)3(Phen)). Among the materials mentioned above, the organometallic iridium complexes with a pyrimidine framework exhibit very high reliability and very high light emission efficiency and are therefore particularly preferred.

[0115] Examples of the substance exhibiting an emission peak in the yellow or red wavelength range include organometallic iridium complexes with a pyrimidine framework, such as: (Diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), Bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)) and Bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm)2(dpm)); organometallic iridium complexes with a pyrazine framework, such as (Acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: Ir(tppr)2(acac)), Bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)) and (Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (Abbreviation: Ir(Fdpq)2(acac)); organometallic iridium complexes with a pyridine skeleton, such as Tris(1-phenylisoquinolinato-N,C 2' )iridium(III) (abbreviation: Ir(piq)3) and bis(1-phenylisoquinolinato-N,C 2' )iridium(III)acetylacetonate (abbreviation: Ir(piq)2(acac)); a platinum complex, such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin-platinum(II) (abbreviation: PtOEP); and rare earth metal complexes, such as tris(1,3-diphenyl-1,3-propanediumato)(monophenanthroline)europium(III) (abbreviation: Eu(DBM)3(Phen)) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: Eu(TTA)3(Phen)). Among the materials mentioned above, the organometallic iridium complexes with a pyrimidine framework exhibit very high reliability and very high light emission efficiency and are therefore particularly preferred. Furthermore, the organometallic iridium complex with a pyrazine framework can exhibit red light emission with advantageous chromaticity.

[0116] The above-described organometallic iridium complexes comprising a five-membered nitrogen-containing heterocyclic framework, such as a 4H-triazole framework, a 1H-triazole framework and an imidazole framework, and the above-described iridium complexes comprising a pyridine framework, exhibit ligands with low electron acceptor properties and readily exhibit a high HOMO level; therefore, these complexes are suitable for an embodiment of the present invention.

[0117] Among the aforementioned organometallic iridium complexes comprising a five-membered nitrogen-containing heterocyclic framework, at least those iridium complexes having a substituent comprising a cyano group can be advantageously used for the light-emitting element of an embodiment of the present invention because, thanks to the high electron-withdrawing property of the cyano group, they exhibit appropriately reduced LUMO and HOMO levels. Furthermore, a light-emitting element comprising one of the iridium complexes can emit blue light with high emission efficiency, since the iridium complexes have a high triplet excitation energy level. Because the iridium complexes are very resistant to repeated oxidation and reduction, a light-emitting element containing one of the iridium complexes can have a long service life.

[0118] It should be noted that, with regard to stability and reliability of the elemental properties, the iridium complex preferably comprises a ligand in which an aryl group, which includes a cyano group, is bonded to the five-membered nitrogenous heterocyclic framework, and the number of carbon atoms of the aryl group is preferably 6 to 13. In this case, the iridium complex can be vacuum-evaporated at a relatively low temperature, making it unlikely that it will degrade due to pyrolysis or the like during evaporation.

[0119] The iridium complex, which includes a ligand in which a cyano group is bonded via an arylene group to a nitrogen atom of a five-membered nitrogenous heterocyclic framework, can maintain a high triplet excitation energy level and can therefore be advantageously used in a light-emitting element that emits high-energy light, such as blue light. The light-emitting element containing the iridium complex can emit high-energy light, such as blue light, with higher efficiency than a light-emitting element that does not include a cyano group. Furthermore, a highly reliable light-emitting element that emits high-energy light, such as blue light, can be obtained by bonding a cyano group to a specific site, as described above.It should be noted that the five-membered nitrogenous heterocyclic skeleton and the cyano group are preferably bonded to each other via an arylene group, such as a phenylene group.

[0120] If the number of carbon atoms in the arylene group is 6 to 13, the iridium complex is a compound with a relatively low molecular weight, making it suitable for vacuum evaporation (allowing it to be evaporated under vacuum at a relatively low temperature). Generally, a compound with a lower molecular weight tends to exhibit lower heat resistance after film formation. However, the iridium complex described above, even with a low molecular weight ligand, has the following advantage: sufficient heat resistance can be ensured because the iridium complex comprises a variety of ligands.

[0121] This means that, in addition to ease of evaporation and electrochemical stability, the iridium complex has the following characteristic: a high triplet excitation energy level. Consequently, the iridium complex is preferably used as a guest material in a light-emitting layer in a light-emitting element of an embodiment of the present invention, particularly in an element that emits blue light. <<Beispiel für Iridiumkomplex> >

[0122] This iridium complex is represented by the general formula (G1).

[0123] In the general formula (G1) Ar 1 and Ar 2 Each of these groups can be independently represented by a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of aryl groups with 6 to 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl. In cases where the aryl group includes a substituent, the substituent can also be an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl.Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of an aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group.

[0124] Q 1 and Q 2 Each independently represents N or CR, and R represents hydrogen, an alkyl group with 1 to 6 carbon atoms, a haloalkyl group with 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Q 1 and / or Q 2 CR includes / includes. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. The haloalkyl group with 1 to 6 carbon atoms is an alkyl group in which at least one hydrogen atom is replaced by an element of Group 17 (fluorine, chlorine, bromine, iodine, or astatine). Examples of the haloalkyl group with 1 to 6 carbon atoms include an alkyl fluoride group, an alkyl chloride group, an alkyl bromide group, and an alkyl iodide group. Specific examples include a methyl fluoride group, a methyl chloride group, an ethyl fluoride group, and an ethyl chloride group. It should be noted that the number and types of halogen elements can be one, two, or more.Specific examples of aryl groups with 6 to 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl groups. The aryl group can contain a substituent, and aryl substituents can be bonded together to form a ring. Alternatively, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or an aryl group with 6 to 13 carbon atoms can be chosen as the substituent. Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl groups. Specific examples of the cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group.

[0125] At least one of the aryl groups represented by Ar 1 and Ar 2 can be represented, and the aryl group, represented by R, includes a cyano group.

[0126] An iridium complex that can be advantageously used for a light-emitting element of an embodiment of the present invention is preferably an ortho-metallated complex. This iridium complex is represented by the general formula (G2).

[0127] In the general formula (G2), Ar represents 1 A 6-carbon aryl group is a substituted or unsubstituted group with 6 to 13 carbon atoms. Specific examples of 6-carbon aryl groups include phenyl, naphthyl, biphenyl, and fluorenyl groups. If the aryl group has a substituent, the substituent can also be an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or a 6-carbon aryl group with 6 to 13 carbon atoms. Specific examples of 1-carbon alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl groups.Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of an aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group.

[0128] R 1 to R 4 Each of these groups independently represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, a substituted or unsubstituted aryl group with 6 to 13 carbon atoms, and a cyano group. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The case in which R 1 to R 4 Each of which uses hydrogen, is advantageous in terms of the simplicity of synthesis and material costs.

[0129] Q 1 and Q 2 Each independently represents N or CR, and R represents hydrogen, an alkyl group with 1 to 6 carbon atoms, a haloalkyl group with 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Q 1 and / or Q 2 CR includes / includes. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. The haloalkyl group with 1 to 6 carbon atoms is an alkyl group in which at least one hydrogen atom is replaced by an element of Group 17 (fluorine, chlorine, bromine, iodine, or astatine). Examples of the haloalkyl group with 1 to 6 carbon atoms include an alkyl fluoride group, an alkyl chloride group, an alkyl bromide group, and an alkyl iodide group. Specific examples include a methyl fluoride group, a methyl chloride group, an ethyl fluoride group, and an ethyl chloride group. It should be noted that the number and types of halogen elements can be one, two, or more.Specific examples of aryl groups with 6 to 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl groups. The aryl group can contain a substituent, and aryl substituents can be bonded together to form a ring. Alternatively, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or an aryl group with 6 to 13 carbon atoms can be chosen as the substituent. Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl groups. Specific examples of the cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group.

[0130] At least one of R 1 to R 4 and the aryl groups formed by Ar 1 and R 1 to R 4 as well as R being represented, comprises a cyano group.

[0131] An iridium complex that can be advantageously used for a light-emitting element of an embodiment of the present invention comprises a 4H-triazole framework as a ligand, which is preferable because the iridium complex can have a high triplet excitation energy level and can be advantageously used in a light-emitting element that emits high-energy light, such as blue light. This iridium complex is represented by the general formula (G3).

[0132] In the general formula (G3), Ar represents 1 A 6-carbon aryl group is a substituted or unsubstituted group with 6 to 13 carbon atoms. Specific examples of 6-carbon aryl groups include phenyl, naphthyl, biphenyl, and fluorenyl groups. If the aryl group has a substituent, the substituent can also be an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or a 6-carbon aryl group with 6 to 13 carbon atoms. Specific examples of 1-carbon alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl groups.Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of an aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group.

[0133] R 1 to R 4 Each of these groups independently represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, a substituted or unsubstituted aryl group with 6 to 13 carbon atoms, and a cyano group. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The case in which R 1 to R 4 Each of which uses hydrogen, is advantageous in terms of the simplicity of synthesis and material costs.

[0134] R 5 Represents one or more hydrogen atoms, an alkyl group with 1 to 6 carbon atoms, a haloalkyl group with 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. The haloalkyl group with 1 to 6 carbon atoms is an alkyl group in which at least one hydrogen atom is replaced by an element from Group 17 (fluorine, chlorine, bromine, iodine, or astatine). Examples of the haloalkyl group with 1 to 6 carbon atoms include an alkyl fluoride group, an alkyl chloride group, an alkyl bromide group, and an alkyl iodide group.Specific examples include a methyl fluoride group, a methyl chloride group, an ethyl fluoride group, and an ethyl chloride group. It should be noted that the number and types of halogen elements can be one, two, or more. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The aryl group can include a substituent, and substituents of the aryl group can be bonded together to form a ring. An alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or an aryl group with 6 to 13 carbon atoms can also be chosen as the substituent.Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl. Specific examples of cycloalkyl groups with 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Specific examples of aryl groups with 6 to 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl.

[0135] At least one of R 1 to R 4 and the aryl groups formed by Ar 1 and R 1 to R 5 The representation includes a cyano group.

[0136] An iridium complex that can be advantageously used for a light-emitting element of an embodiment of the present invention comprises an imidazole framework as a ligand, which is preferable because the iridium complex can have a high triplet excitation energy level and can be advantageously used in a light-emitting element that emits high-energy light, such as blue light. This iridium complex is represented by the general formula (G4).

[0137] In the general formula (G4) Ar represents 1 A 6-carbon aryl group is a substituted or unsubstituted group with 6 to 13 carbon atoms. Specific examples of 6-carbon aryl groups include phenyl, naphthyl, biphenyl, and fluorenyl groups. If the aryl group has a substituent, the substituent can also be an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or a 6-carbon aryl group with 6 to 13 carbon atoms. Specific examples of 1-carbon alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl groups.Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of an aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group.

[0138] R 1 to R 4 Each of these groups independently represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The case in which R 1 to R 4 Each of which uses hydrogen, is advantageous in terms of the simplicity of synthesis and material costs.

[0139] R 5 and R 6 Each of these groups independently represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, a haloalkyl group with 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. The haloalkyl group with 1 to 6 carbon atoms is an alkyl group in which at least one hydrogen atom is replaced by an element from Group 17 (fluorine, chlorine, bromine, iodine, or astatine). Examples of the haloalkyl group with 1 to 6 carbon atoms include an alkyl fluoride group, an alkyl chloride group, an alkyl bromide group, and an alkyl iodide group.Specific examples include a methyl fluoride group, a methyl chloride group, an ethyl fluoride group, and an ethyl chloride group. It should be noted that the number and types of halogen elements can be one, two, or more. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The aryl group can include a substituent, and substituents of the aryl group can be bonded together to form a ring. An alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or an aryl group with 6 to 13 carbon atoms can also be chosen as the substituent.Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl. Specific examples of cycloalkyl groups with 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Specific examples of aryl groups with 6 to 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl.

[0140] At least one of R 1 to R 4 and the aryl groups formed by Ar 1 and R 1 to R 6 The representation includes a cyano group.

[0141] An iridium complex that can be advantageously used for a light-emitting element of an embodiment of the present invention comprises a five-membered nitrogen-containing heterocyclic framework, and an aryl group bonded to the nitrogen of the framework is preferably a substituted or unsubstituted phenyl group. In this case, the iridium complex can be vacuum-evaporated at a relatively low temperature and exhibits a high triplet excitation energy level, and thus it can be used in a light-emitting element that emits high-energy light, such as blue light. The iridium complex is represented by the general formula (G5) or (G6).

[0142] In the general formula (G5) R 7 and R 11 each represents an alkyl group with 1 to 6 carbon atoms, and R 7 and R 11 They exhibit the same structure. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group.

[0143] R 8 to R 10 Each of these groups independently represents hydrogen, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, a substituted or unsubstituted phenyl group, or a cyano group. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. It should be noted that at least one of R 8 to R 10 preferably includes a cyano group.

[0144] R 1 to R 4 Each of these groups independently represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The case in which R 1 to R 4 Each of which uses hydrogen, is advantageous in terms of the simplicity of synthesis and material costs.

[0145] R 5 Represents one or more hydrogen atoms, an alkyl group with 1 to 6 carbon atoms, a haloalkyl group with 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. The haloalkyl group with 1 to 6 carbon atoms is an alkyl group in which at least one hydrogen atom is replaced by an element from Group 17 (fluorine, chlorine, bromine, iodine, or astatine). Examples of the haloalkyl group with 1 to 6 carbon atoms include an alkyl fluoride group, an alkyl chloride group, an alkyl bromide group, and an alkyl iodide group.Specific examples include a methyl fluoride group, a methyl chloride group, an ethyl fluoride group, and an ethyl chloride group. It should be noted that the number and types of halogen elements can be one, two, or more. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The aryl group can include a substituent, and substituents of the aryl group can be bonded together to form a ring. An alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or an aryl group with 6 to 13 carbon atoms can also be chosen as the substituent.Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl. Specific examples of cycloalkyl groups with 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Specific examples of aryl groups with 6 to 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl.

[0146] In the general formula (G6) R 7 and R 11 each represents an alkyl group with 1 to 6 carbon atoms, and R 7 and R 11 They exhibit the same structure. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group.

[0147] R 8 to R 10 Each of these groups independently represents hydrogen, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, a substituted or unsubstituted phenyl group, or a cyano group. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. It should be noted that at least one of R 8 to R 10 preferably includes a cyano group.

[0148] R 1 to R 4 Each of these groups independently represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The case in which R 1 to R 4 Each of which uses hydrogen, is advantageous in terms of the simplicity of synthesis and material costs.

[0149] R 5 and R 6 Each of these groups independently represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, a haloalkyl group with 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. The haloalkyl group with 1 to 6 carbon atoms is an alkyl group in which at least one hydrogen atom is replaced by an element from Group 17 (fluorine, chlorine, bromine, iodine, or astatine). Examples of the haloalkyl group with 1 to 6 carbon atoms include an alkyl fluoride group, an alkyl chloride group, an alkyl bromide group, and an alkyl iodide group.Specific examples include a methyl fluoride group, a methyl chloride group, an ethyl fluoride group, and an ethyl chloride group. It should be noted that the number and types of halogen elements can be one, two, or more. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The aryl group can include a substituent, and substituents of the aryl group can be bonded together to form a ring. An alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or an aryl group with 6 to 13 carbon atoms can also be chosen as the substituent.Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl. Specific examples of cycloalkyl groups with 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Specific examples of aryl groups with 6 to 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl.

[0150] An iridium complex that can be advantageously used for a light-emitting element of an embodiment of the present invention comprises a 1H-triazole framework as a ligand, which is preferable because the iridium complex can have a high triplet excitation energy level and can be advantageously used in a light-emitting element that emits high-energy light, such as blue light. This iridium complex is represented by the general formula (G7) or (G8).

[0151] In the general formula (G7) Ar represents 1 A 6-carbon aryl group is a substituted or unsubstituted group with 6 to 13 carbon atoms. Specific examples of 6-carbon aryl groups include phenyl, naphthyl, biphenyl, and fluorenyl groups. If the aryl group has a substituent, the substituent can also be an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or a 6-carbon aryl group with 6 to 13 carbon atoms. Specific examples of 1-carbon alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl groups.Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of an aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group.

[0152] R 1 to R 4 Each of these groups independently represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The case in which R 1 to R 4 Each of which uses hydrogen, is advantageous in terms of the simplicity of synthesis and material costs.

[0153] R 6 Represents one or more hydrogen atoms, an alkyl group with 1 to 6 carbon atoms, a haloalkyl group with 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. The haloalkyl group with 1 to 6 carbon atoms is an alkyl group in which at least one hydrogen atom is replaced by an element from Group 17 (fluorine, chlorine, bromine, iodine, or astatine). Examples of the haloalkyl group with 1 to 6 carbon atoms include an alkyl fluoride group, an alkyl chloride group, an alkyl bromide group, and an alkyl iodide group.Specific examples include a methyl fluoride group, a methyl chloride group, an ethyl fluoride group, and an ethyl chloride group. It should be noted that the number and types of halogen elements can be one, two, or more. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The aryl group can include a substituent, and substituents of the aryl group can be bonded together to form a ring. An alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or an aryl group with 6 to 13 carbon atoms can also be chosen as the substituent.Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl. Specific examples of cycloalkyl groups with 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Specific examples of aryl groups with 6 to 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl.

[0154] At least one of R 1 to R 4 and the aryl groups formed by Ar 1 , R 1 to R 4 and R 6 The representation includes a cyano group.

[0155] In the general formula (G8) R 7 and R 11 each represents an alkyl group with 1 to 6 carbon atoms, and R 7 and R 11 They exhibit the same structure. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group.

[0156] R 8 to R 10 Each of these groups independently represents hydrogen, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, a substituted or unsubstituted phenyl group, or a cyano group. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. It should be noted that at least one of R 8 to R 10 preferably includes a cyano group.

[0157] R 1 to R 4 Each of these groups independently represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The case in which R 1 to R 4 Each of which uses hydrogen, is advantageous in terms of the simplicity of synthesis and material costs.

[0158] R 6 Represents one or more hydrogen atoms, an alkyl group with 1 to 6 carbon atoms, a haloalkyl group with 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group with 6 to 13 carbon atoms. Specific examples of the alkyl group with 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. The haloalkyl group with 1 to 6 carbon atoms is an alkyl group in which at least one hydrogen atom is replaced by an element from Group 17 (fluorine, chlorine, bromine, iodine, or astatine). Examples of the haloalkyl group with 1 to 6 carbon atoms include an alkyl fluoride group, an alkyl chloride group, an alkyl bromide group, and an alkyl iodide group.Specific examples include a methyl fluoride group, a methyl chloride group, an ethyl fluoride group, and an ethyl chloride group. It should be noted that the number and types of halogen elements can be one, two, or more. Specific examples of the aryl group with 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. The aryl group can include a substituent, and substituents of the aryl group can be bonded together to form a ring. An alkyl group with 1 to 6 carbon atoms, a cycloalkyl group with 3 to 6 carbon atoms, or an aryl group with 6 to 13 carbon atoms can also be chosen as the substituent.Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl. Specific examples of cycloalkyl groups with 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Specific examples of aryl groups with 6 to 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl.

[0159] As alkyl group and aryl group, which are connected by R 1 to R 4 Groups represented by the structural formulas (R-1) to (R-29), for example, can be used in the general formulas (G2) to (G8). It should be noted that groups that can be used as alkyl and aryl groups are not limited to these.

[0160] For example, groups represented by the structural formulas (R-12) to (R-29) can be described as aryl groups, denoted by Ar 1 represented in the general formulas (G1) to (G4) and (G7), and used as an aryl group, which is represented by Ar 2 is represented in the general formula (G1). It should be noted that groups which are for Ar 1 and Ar 2 can be used, but are not limited to these groups.

[0161] For example, the groups represented by the structural formulas (R-1) to (R-10) can be used as alkyl groups, which are represented by R 7 and R 11 They are represented in the general formulas (G5), (G6) and (G8). It should be noted that groups which can be used as alkyl groups are not limited to these groups.

[0162] As an alkyl group or substituted or unsubstituted phenyl group, which is represented by R 8 to R 10 Groups represented by the structural formulas (R-1) to (R-22) above, as shown in the general formulas (G5), (G6) and (G8), can be used, for example. It should be noted that groups that can be used for the alkyl or phenyl group are not limited to these.

[0163] For example, groups represented by structural formulas (R-1) to (R-29) and structural formulas (R-30) to (R-37) can be used as alkyl groups, aryl groups and haloalkyl groups, respectively, represented by R 5 in the general formulas (G3) to (G6) and by R 6 in the general formulas (G4) and (G6) to (G8). It should be noted that a group which can be used as an alkyl group, aryl group or haloalkyl group is not limited to these groups. <<Spezifische Beispiele für Iridiumkomplexe> >

[0164] Specific examples of structures of the iridium complexes represented by the general formulas (G1) to (G8) are compounds represented by the structural formulas (100) to (134). It should be noted that the iridium complexes represented by the general formulas (G1) to (G8) are not limited to the examples shown below.

[0165] The iridium complexes mentioned above by way of example each exhibit relatively low HOMO and LUMO levels, as described above, and are therefore preferred as guest material for a light-emitting element in an embodiment of the present invention. In this case, the light-emitting element can have a high emission efficiency. Furthermore, the iridium complexes mentioned above by way of example each exhibit a high triplet excitation energy level, and are therefore particularly preferred as guest material for an element that emits blue light. In this case, the element that emits blue light can have a high emission efficiency. Moreover, since the iridium complexes mentioned above by way of example are each very resistant to repeated oxidation and reduction, a light-emitting element containing one of the iridium complexes can have a long operating lifetime.

[0166] Any material capable of converting triplet excitation energy into light emission can be used as the light-emitting material contained in light-emitting layer 130. In addition to a phosphorescent material, a thermally activated delayed fluorescent (TADF) material can be specified as an example of a material capable of converting triplet excitation energy into light emission. Therefore, it is acceptable to replace "phosphorescent material" with "thermally activated delayed fluorescent material" in the description.It should be noted that the thermally activated delayed fluorescent material (TADF) is a material that exhibits a small difference between the triplet and singlet excitation energy levels and a function for converting triplet excitation energy to singlet excitation energy via reverse intersystem crossing. Thus, the TADF material can, using a small amount of thermal energy, upgrade from a triplet excitation state to a singlet excitation state (i.e., reverse intersystem crossing is possible) and efficiently emit light (fluorescence) from the singlet excitation state.The TADF is efficiently obtained under the condition that the energy difference between the triplet excitation energy level and the singlet excitation energy level is preferably greater than 0 eV and less than or equal to 0.2 eV, more preferably greater than 0 eV and less than or equal to 0.1 eV.

[0167] In the case where the thermally activated delayed fluorescence material consists of one type of material, any of the following materials can be used, for example.

[0168] Firstly, fullerenes, a derivative thereof, or an acridine derivative such as proflavin, eosin, and the like can be identified. Furthermore, a metal-containing porphyrin can be identified, such as a porphyrin containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of metal-containing porphyrin include a protoporphyrin tin fluoride complex (SnF2(Proto IX)), a mesoporphyrin tin fluoride complex (SnF2(Meso IX)), a hematoporphyrin tin fluoride complex (SnF2(Hämato IX)), a coproporphyrin tetramethyl ester tin fluoride complex (SnF2(Copro III-4Me)), an octaethylporphyrin tin fluoride complex (SnF2(OEP)), an etioporphyrin tin fluoride complex (SnF2(Etio I)) and an octaethylporphyrin platinum chloride complex (PtCl2(OEP)).

[0169] For the thermally activated, delayed-release fluorescent material, which consists of a single material type, a heterocyclic compound comprising a π-electron-rich heteroaromatic ring and a π-electron-poor heteroaromatic ring can also be used. In particular, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-Phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-Phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-Phenyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-Dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), Bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS) or 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA) can be used. The heterocyclic compound is preferred because it has both the π-electron-rich heteroaromatic ring and the π-electron-poor heteroaromatic ring; therefore, its electron transport and hole transport properties are high.Among frameworks with the π-electron-deficient heteroaromatic ring, a diazine framework (a pyrimidine framework, a pyrazine framework, or a pyridazine framework) and a triazine framework exhibit high stability and reliability and are particularly preferable. Among frameworks with the π-electron-rich heteroaromatic ring, an acridine framework, a phenoxazine framework, a thiophene framework, a furan framework, and a pyrrole framework exhibit high stability and reliability; consequently, one or more of these frameworks are preferably included. An indole framework, a carbazole framework, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole framework is particularly preferable as a pyrrole framework.It should be noted that a substance in which the π-electron-rich heteroaromatic ring is directly bonded to the π-electron-poor heteroaromatic ring is particularly preferred, since both the donor property of the π-electron-rich heteroaromatic ring and the acceptor property of the π-electron-poor heteroaromatic ring are increased, and the difference between the singlet excitation energy level and the triplet excitation energy level becomes small.

[0170] The light-emitting layer 130 can have a structure in which two or more layers are arranged one above the other. For example, if the light-emitting layer 130 is formed by stacking a first light-emitting layer and a second light-emitting layer in that order from the hole-transport layer side, the first light-emitting layer is formed using a substance with hole-transport properties as its host material, and the second light-emitting layer is formed using a substance with electron-transport properties as its host material. A light-emitting material contained in the first light-emitting layer can be the same as or different from a light-emitting material contained in the second light-emitting layer.Furthermore, the materials can have functions for emitting light of the same color or light of different colors. Two types of light-emitting materials with functions for emitting light of different colors are used for the two light-emitting layers, so that light of a variety of emission colors can be obtained simultaneously. The light-emitting materials of the light-emitting layers are particularly preferably selected such that white light can be obtained by combining the light emission from the two light-emitting layers.

[0171] The light-emitting layer 130 can contain an additional material besides the host material 131 and the guest material 132.

[0172] It should be noted that the light-emitting layer 130 can be formed by an evaporation process (including a vacuum evaporation process), an inkjet process, a coating process, gravure printing, or the like. In addition to the materials mentioned above, an inorganic compound, such as a quantum dot, or a high-molecular-weight compound (e.g., an oligomer, a dendrimer, and a polymer) can be incorporated into the light-emitting layer 130. < <lochinjektionsschicht>>

[0173] The hole injection layer 111 has a function of reducing the barrier to hole injection from one electrode of the electrode pair (electrode 101 or electrode 102) to promote hole injection and is formed, for example, using a transition metal oxide, a phthalocyanine derivative, or an aromatic amine. The transition metal oxide can be molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, or the like. The phthalocyanine derivative can be phthalocyanine, metal phthalocyanine, or the like. The aromatic amine can be a benzidine derivative, a phenylenediamine derivative, or the like. It is also possible to use a high-molecular-weight compound, such as polythiophene or polyaniline; a typical example is poly(ethylenedioxythiophene) / poly(styrenesulfonic acid), which is a self-doped polythiophene.

[0174] A hole injection layer 111 can also be a layer containing a composite material of a hole transport material and a material exhibiting the property of accepting electrons from the hole transport material. Alternatively, a layer arrangement consisting of a layer containing a material with electron-accepting properties and a layer containing a hole transport material can be used. In a stable state or in the presence of an electric field, electrical charges can be transferred between these materials. Examples of materials exhibiting electron-accepting properties include organic acceptors such as a quinodimethane derivative, a chloranil derivative, and a hexaazatriphenylene derivative. A specific example is a compound with an electron-withdrawing group (a halogen group or a cyano group), such as...7,7,8,8-Tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, or 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN). Alternatively, a transition metal oxide, such as an oxide of a metal from Groups 4 to 8, can be used. In particular, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, or the like can be used. Molybdenum oxide is especially preferred because it is stable in air, has low hygroscopic properties, and is easy to handle.

[0175] A material that has the property of transporting more holes than electrons can be used as a hole transport material, where a material with a hole mobility of 1 × 10 -6 cm 2 / Vs or higher is preferable. In particular, any aromatic amine, carbazole derivative, aromatic hydrocarbon, stilbene derivative, and the like, which have been described as examples of hole transport material that can be used in light-emitting layer 130, may be used. Furthermore, the hole transport material may be a high-molecular-weight compound. < <lochtransportschicht>>

[0176] The hole transport layer 112 is a layer containing a hole transport material and can be configured using any of the hole transport materials given as examples of the material for the hole injection layer 111. For the hole transport layer 112 to function as a transporter of holes injected into the hole injection layer 111 to the light-emitting layer 130, the HOMO level of the hole transport layer 112 is preferably equal to or close to the HOMO level of the hole injection layer 111.

[0177] Preferably, a substance with a hole mobility of 1 × 10 -6 cm 2 / Vs or higher is used as a hole transport material. It should be noted that a substance other than the aforementioned substances may be used as long as its hole transport property is higher than its electron transport property. The layer containing a substance with a high hole transport property is not limited to a single layer, and two or more layers containing the aforementioned substances may be stacked on top of each other. < <elektronentransportschicht>>

[0178] The electron transport layer 118 has the function of transporting electrons injected from the other electrode of the electrode pair (electrode 101 or electrode 102) via the electron injection layer 119 to the light-emitting layer 130. A material exhibiting the property of transporting more electrons than holes can be used as the electron transport material, with a material having an electron mobility of 1 × 10 -6 cm 2 / Vs or higher is preferable. For example, a π-electron-deficient heteroaromatic compound, such as a nitrogen-containing heteroaromatic compound, a metal complex, or the like, can be used as a compound that readily accepts electrons (the material with electron transport properties). In particular, a metal complex with a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand, which have been described as electron transport materials that can be used in the light-emitting layer 130, an oxadiazole derivative, a triazole derivative, a benzimidazole derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a phenanthroline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, and a triazine derivative can be specified. A substance with an electron mobility of 1 × 10 -6 cm 2 A value of / Vs or higher is preferred. It should be noted that a substance other than these substances, which has the property of transporting more electrons than holes, may be used for the electron transport layer. The electron transport layer 118 is not limited to a single layer and may be a layer arrangement of two or more layers containing the aforementioned substances.

[0179] A layer controlling electron carrier transfer can be provided between the electron transport layer 118 and the light-emitting layer 130. This electron carrier transfer control layer is formed by adding a small amount of a substance with high electron capture properties to a material with high electron transport properties as described above. The layer can regulate the charge carrier balance by suppressing electron carrier movement. Such a structure is very effective in preventing a problem (such as a reduction in the lifetime of the element) that arises when electrons pass through the light-emitting layer. < <elektroneninjektionsschicht>>

[0180] The electron injection layer 119 has a function for reducing the barrier to electron injection from the electrode 102 in order to promote electron injection, and can be formed, for example, using a metal of group 1 or a metal of group 2, or an oxide, halide, or carbonate of one of the metals. Alternatively, a composite material can be used that includes an electron transport material (described above) and a material that has the property of donating electrons to the electron transport material. The material that has the property of donating electrons can be a metal of group 1, a metal of group 2, an oxide of one of the metals, or the like. In particular, an alkali metal, an alkaline earth metal, or a compound thereof, such as...Lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2) or lithium oxide (LiO). x ). Alternatively, a rare-earth metal compound, such as erbium fluoride (ErF3), can be used. An electride can also be used for the electron injection layer 119. Examples of electrides include substances in which electrons have been added to calcium oxide-aluminum oxide in a high concentration. The electron injection layer 119 can be formed using the same substance that can be used for the electron transport layer 118.

[0181] A composite material in which an organic compound and an electron donor (donor) are mixed can also be used for the electron injection layer 119. Such a composite material exhibits excellent electron injection and electron transport properties, since electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that can transport the generated electrons excellently. In particular, for example, the substances listed above (e.g., the metal complexes and heteroaromatic compounds) can be used to form the electron transport layer 118. A substance that has an electron-donating property with respect to the organic compound can be used as the electron donor.In particular, an alkali metal, an alkaline earth metal, and a rare earth metal are preferred, and lithium, sodium, cesium, magnesium, calcium, erbium, and ytterbium are acceptable. Furthermore, an alkali metal oxide or an alkaline earth metal oxide is preferred, and lithium oxide, calcium oxide, barium oxide, and the like are acceptable. A Lewis base, such as magnesium oxide, may also be used. An organic compound, such as tetrathiafulvalene (abbreviation: TTF), may also be used.

[0182] It should be noted that the light-emitting layer, the hole injection layer, the hole transport layer, the electron transport layer, and the electron injection layer described above can each be formed by an evaporation process (including a vacuum evaporation process), an inkjet process, a coating process, a gravure printing process, or the like. In addition to the materials mentioned above, an inorganic compound, such as a quantum dot, or a high-molecular-weight compound (e.g., an oligomer, a dendrimer, and a polymer) can be used in the light-emitting layer, the hole injection layer, the hole transport layer, the electron transport layer, and the electron injection layer.

[0183] The quantum dot can be, for example, a gelatinous quantum dot, an alloyed quantum dot, a core-shell quantum dot, or a core-quantum quantum dot. A quantum dot containing elements from groups 2 and 16, elements from groups 13 and 15, elements from groups 13 and 17, elements from groups 11 and 17, or elements from groups 14 and 15 can be used. Alternatively, a quantum dot containing an element such as cadmium (Cd), selenium (Se), zinc (Zn), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), arsenic (As), or aluminum (Al) can be used. <<Paar von Elektroden> >

[0184] Electrodes 101 and 102 serve as the anode and cathode of each light-emitting element. Electrodes 101 and 102 can be formed using a metal, an alloy, a conductive compound, a mixture, or a layered arrangement of these or the like.

[0185] The electrode 101 or the electrode 102 is preferably designed using a conductive material with a light-reflecting function. Examples of the conductive material include aluminum (Al), an alloy containing Al, and the like. Examples of the alloy containing Al include an alloy containing Al and L (L representing one or more of titanium (Ti), neodymium (Nd), nickel (Ni), and lanthanum (La)), such as an alloy containing Al and Ti, and an alloy containing Al, Ni, and La. Aluminum has low resistance and high light reflectivity. Aluminum is abundant in the Earth's crust and is inexpensive; consequently, it is possible to reduce the cost of manufacturing a light-emitting element using aluminum.Alternatively, silver (Ag), an alloy of Ag and N (where N represents one or more of yttrium (Y), Nd, magnesium (Mg), ytterbium (Yb), Al, Ti, gallium (Ga), zinc (Zn), indium (In), tungsten (W), manganese (Mn), tin (Sn), iron (Fe), Ni, copper (Cu), palladium (Pd), iridium (Ir), and gold (Au)), or the like may be used. Examples of silver-containing alloys include an alloy containing silver, palladium, and copper; an alloy containing silver and copper; an alloy containing silver and magnesium; an alloy containing silver and nickel; an alloy containing silver and gold; an alloy containing silver and ytterbium; and the like. In addition, a transition metal, such as tungsten, chromium (Cr), molybdenum (Mo), copper, or titanium, may be used.

[0186] Light emitted by the light-emitting layer is extracted via electrode 101 and / or electrode 102. Accordingly, at least one of the electrodes 101 and 102 is preferably formed using a conductive material with a light-transmitting function. The conductive material used can be a material whose transmittance for visible light is greater than or equal to 40% and less than or equal to 100%, preferably greater than or equal to 60% and less than or equal to 100%, and whose resistivity is less than or equal to 1 × 10⁻⁶. -2 Ω·cm is.

[0187] Electrodes 101 and 102 can each be configured using a conductive material with properties for transmitting and reflecting light. The conductive material can be one whose reflectivity for visible light is greater than or equal to 20% and less than or equal to 80%, preferably greater than or equal to 40% and less than or equal to 70%, and whose resistivity is less than or equal to 1 × 10⁻⁶. 2 Ω·cm. For example, one or more types of conductive metals and alloys, conductive compounds, and the like may be used. In particular, a metal oxide such as indium tin oxide (hereinafter referred to as ITO), silicon- or silicon-oxide-containing indium tin oxide (ITSO), indium zinc oxide, titanium-containing indium tin oxide, indium titanium oxide, or tungsten oxide and zinc oxide-containing indium oxide may be used. A thin metal film with a thickness that allows the transmission of light (preferably a thickness greater than or equal to 1 nm and less than or equal to 30 nm) may also be used. The metal may be Ag, an alloy of Ag and Al, an alloy of Ag and Mg, an alloy of Ag and Au, an alloy of Ag and Yb, or the like.

[0188] In this description and similar texts, the term "transmitting material" refers to a material that transmits visible light and exhibits conductivity. Examples of such a material include, in addition to the oxide conductor described above, of which ITO is a typical example, an oxide semiconductor and an organic conductor containing an organic substance. Examples of the organic conductor containing an organic substance include a composite material in which an organic compound and an electron donor (donor material) are mixed, and a composite material in which an organic compound and an electron acceptor (acceptor material) are mixed. Alternatively, a carbon-based inorganic material, such as graphene, may be used. The resistivity of the material is preferably less than or equal to 1 × 10⁻⁶. 5 Ω·cm, preferably lower than or equal to 1 × 10 4 Ω·cm.

[0189] Alternatively, electrode 101 and / or electrode 102 can be formed by arranging two or more of these materials on top of each other.

[0190] To improve light extraction efficiency, a material with a higher refractive index than that of a transmitting electrode can be formed in contact with the electrode. The material can be electrically conductive or non-conductive, as long as it transmits visible light. In addition to the oxide conductors described above, an oxide semiconductor and an organic compound can be given as examples of the material. Examples of the organic compound include materials for the light-emitting layer, the hole injection layer, the hole transport layer, the electron transport layer, and the electron injection layer. Alternatively, a carbon-based inorganic material or a metal film thin enough to transmit light can be used.As another alternative, a large number of layers, each formed using the material with a high refractive index and with a thickness of several nanometers to several tens of nanometers, can be arranged on top of each other.

[0191] In the case where electrode 101 or electrode 102 serves as the cathode, the electrode preferably contains a material with a low work function (less than or equal to 3.8 eV). Examples include an element belonging to Group 1 or 2 of the periodic table (e.g., an alkali metal such as lithium, sodium, or cesium; an alkaline earth metal such as calcium or strontium; or magnesium); an alloy containing one of these elements (e.g., Ag-Mg or Al-Li); a rare earth metal such as europium (Eu) or Yb; an alloy containing one of these rare earth metals; an alloy containing aluminum and silver; and the like.

[0192] If electrode 101 or electrode 102 is used as the anode, a material with a high work function (4.0 eV or higher) is preferably used.

[0193] Electrode 101 and electrode 102 can be a multilayer consisting of a conductive material with a light-reflecting function and a conductive material with a light-transmitting function. In this case, electrode 101 and electrode 102 can have an optical path length matching function, such that light of a desired wavelength emitted by each light-emitting layer oscillates and is amplified, which is preferable.

[0194] Depending on requirements, a sputtering process, an evaporation process, a printing process, a coating process, a molecular beam epitaxy (MBE) process, a CVD process, a pulsed laser deposition process, an atomic layer deposition (ALD) process or the like can be used as a method for forming the electrode 101 and the electrode 102. < <substrat>>

[0195] A light-emitting element of an embodiment of the present invention can be formed on a substrate made of glass, plastic, or the like. As one possibility for arranging layers on top of each other on the substrate, layers can be arranged sequentially from the side of electrode 101 or sequentially from the side of electrode 102.

[0196] For the substrate on which the light-emitting element of an embodiment of the present invention can be formed, glass, quartz, plastic, or the like can be used, for example. Alternatively, a flexible substrate can be used. The flexible substrate means, for example, a substrate that can be bent, such as a plastic substrate made of polycarbonate or polyarylate. Alternatively, a film, an inorganic film formed by evaporation, or the like can be used. Another material can be used as long as the substrate serves as a support in a manufacturing process of the light-emitting element or an optical element, or as long as it has a function of protecting the light-emitting element or an optical element.

[0197] For example, in this description and the like, a light-emitting element can be formed using various substrates. The type of substrate is not particularly restricted. Examples of substrates include a semiconductor substrate (e.g., a single-crystal substrate or a silicon substrate), a SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate containing a stainless steel foil, a tungsten substrate, a substrate containing a tungsten foil, a flexible substrate, a mounting film, cellulose nanofiber (CNF), paper containing a fiber material, a base material film, and the like. Examples of glass substrates include a barium borosilicate glass substrate, an aluminum borosilicate glass substrate, a soda-lime glass substrate, and the like.Examples of flexible substrates, mounting films, base material films, and the like include substrates made of plastics, for which polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE) are typical examples. Another example is a resin, such as acrylic. Furthermore, polypropylene, polyester, polyvinyl fluoride, and polyvinyl chloride can be given as examples. Other examples include polyamide, polyimide, aramid, epoxy, an inorganic film formed by evaporation, paper, and the like.

[0198] Alternatively, a flexible substrate can be used, allowing the light-emitting element to be placed directly above it. Another alternative is to provide a separating layer between the substrate and the light-emitting element. This separating layer can be used when part or all of the light-emitting element formed above the separating layer is separated from the substrate and transferred to another substrate. In such a case, the light-emitting element can be transferred to a substrate with low heat resistance or to a flexible substrate. For the separating layer, for example, a layer arrangement comprising inorganic films, namely a tungsten film and a silicon oxide film, or a structure in which a resin film of polyimide or the like is formed over a substrate can be used.

[0199] In other words, once the light-emitting element has been formed using a substrate, it can be transferred to another substrate. Examples of substrates onto which the light-emitting element is transferred include, in addition to those mentioned above, a cellophane substrate, a rock substrate, a wood substrate, a fabric substrate (including a natural fiber (e.g., silk, cotton, or hemp), a synthetic fiber (e.g., nylon, polyurethane, or polyester), a regenerated fiber (e.g., acetate, cupro, viscose, or regenerated polyester), and the like), a leather substrate, a rubber substrate, and the like. Using such a substrate allows for the formation of a light-emitting element with high durability, high heat resistance, reduced weight, or reduced thickness.

[0200] The light-emitting element 150 can, for example, be formed over an electrode that is electrically connected to a field-effect transistor (FET) formed over one of the substrates described above. In this way, an active-matrix display device can be manufactured in which the FET controls the operation of the light-emitting element 150.

[0201] This embodiment describes one embodiment of the present invention. Further embodiments of the present invention are described in other embodiments. It should be noted that an embodiment of the present invention is not limited to this. That is to say, an embodiment of the present invention is not limited to a specific embodiment, since various embodiments of the present invention are disclosed in this embodiment as well as in other embodiments. Although the example described involves the use of an embodiment of the present invention with a light-emitting element, an embodiment of the present invention is not limited to this. For example, depending on the circumstances or conditions, an embodiment of the present invention need not necessarily be used with a light-emitting element.One embodiment of the present invention, though not limited thereto, shows an example comprising a first organic compound, a second organic compound, and a guest material suitable for converting the triplet excitation energy into light emission, and in which the LUMO level of the first organic compound is lower than that of the second organic compound, and in which the HOMO level of the first organic compound is lower than that of the second organic compound. Depending on the circumstances or conditions, in one embodiment of the present invention, the LUMO level of the first organic compound need not necessarily be lower than that of the second organic compound. Alternatively, the HOMO level of the first organic compound need not necessarily be lower than that of the second organic compound.One embodiment of the present invention shows, though not limited thereto, an example in which the first organic compound and the second organic compound form an exciplex. Depending on the circumstances or conditions, in one embodiment of the present invention, for example, the first organic compound and the second organic compound need not necessarily form an exciplex. One embodiment of the present invention shows, though not limited thereto, an example in which the LUMO level of the guest material is higher than that of the first organic compound and in which the HOMO level of the guest material is higher than that of the second organic compound. Depending on the circumstances or conditions, in one embodiment of the present invention, for example, the LUMO level of the guest material need not necessarily be higher than that of the first organic compound.Alternatively, the HOMO level of the guest material is not necessarily higher than that of the second organic compound.

[0202] The structure described in this embodiment can be used in a suitable combination with any of the other embodiments. (Version 2)

[0203] In this embodiment, light-emitting elements, each having a structure that differs from that described in embodiment 1, are described below based on Fig. 3A to Fig. 3C and Fig. 4A to Fig. 4C described. In Fig. 3A to Fig. 3C and Fig. 4A to Fig. In some cases, 4C will be a section with a similar function to the one in Fig. 1A through the same hatching pattern as in Fig. Sections are shown in 1A and are not specifically marked with a reference symbol. Furthermore, the same reference symbols are used for sections with similar functions, and a detailed description of the sections is omitted in some cases. <Strukturbeispiel 1 des Licht emittierenden Elements>

[0204] Fig. 3A is a schematic cross-sectional view of a light-emitting element 250.

[0205] The light-emitting element 250, which is in Fig. Figure 3A shows a variety of light-emitting units (one light-emitting unit 106 and one light-emitting unit 108 in Fig. 3A) between a pair of electrodes (electrode 101 and electrode 102). One of the light-emitting units preferably has the same structure as the EL layer 100 described in Fig. 1A and Fig. Figure 1B is shown. That is to say: Preferably the light-emitting element 150 comprises Fig. 1A and Fig. 1B is a light-emitting unit, whereas the light-emitting element 250 comprises a plurality of light-emitting units. It should be noted that electrode 101 serves as the anode and electrode 102 as the cathode in the following description of the light-emitting element 250; however, the functions of the light-emitting element 250 can be interchanged.

[0206] In the light-emitting element 250, which is in Fig. As shown in Figure 3A, the light-emitting unit 106 and the light-emitting unit 108 are arranged one above the other, and a charge-generating layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 108. It should be noted that the light-emitting unit 106 and the light-emitting unit 108 may have the same structure or they may have different structures. For example, the EL layer 100, which is shown in Figure 3A, is arranged in the light-emitting unit 106. Fig. 1A and Fig. 1B is shown, preferably used in the light-emitting unit 108.

[0207] The light-emitting element 250 comprises a light-emitting layer 120 and a light-emitting layer 170. The light-emitting unit 106 comprises, in addition to the light-emitting layer 120, the hole injection layer 111, the hole transport layer 112, an electron transport layer 113, and an electron injection layer 114. The light-emitting unit 108 comprises, in addition to the light-emitting layer 170, a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 119.

[0208] The charge-generating layer 115 can either have a structure in which an acceptor substance, which is an electron acceptor, is added to a hole transport material, or a structure in which a donor substance, which is an electron donor, is added to an electron transport material. Alternatively, both of these structures can be arranged one above the other.

[0209] In the case where the charge-generating layer 115 contains a composite material of an organic compound and an acceptor substance, the composite material that can be used for the hole injection layer 111 described in embodiment 1 can be used for the composite material. Various compounds can be used as the organic compound, such as an aromatic amine compound, a carbazole compound, an aromatic hydrocarbon, and a high-molecular-weight compound (such as an oligomer, a dendrimer, or a polymer). A substance with a hole mobility of 1 × 10⁻⁶ -6 cm 2 A voltage of / Vs or higher is preferably used as an organic compound. It should be noted that another material may be used as long as it has the property of transporting more holes than electrons. Since the composite material of an organic compound and an acceptor substance exhibits excellent charge carrier injection and charge carrier transport properties, operation at a low voltage or low current can be achieved. It should be noted that if a surface of a light-emitting unit, such as that of light-emitting unit 108, is in contact with the charge-generating layer 115 on the anode side, the charge-generating layer 115 can also serve as a hole injection layer or hole transport layer of the light-emitting unit; therefore, a hole injection layer or a hole transport layer need not necessarily be included in the light-emitting unit.

[0210] The charge-generating layer 115 can have a multilayer structure consisting of a layer containing the composite material of an organic compound and an acceptor substance, and a layer containing another material. For example, the charge-generating layer 115 can be formed by combining a layer containing the composite material of an organic compound and an acceptor substance with a layer containing a compound selected from substances with electron-donating properties and a compound with high electron-transport properties. Furthermore, the charge-generating layer 115 can be formed by combining a layer containing the composite material of an organic compound and an acceptor substance with a layer containing a transparent conductive material.

[0211] The charge-generating layer 115, provided between the light-emitting unit 106 and the light-emitting unit 108, can have any structure as long as electrons can be injected into the light-emitting unit on one side and holes can be injected into the light-emitting unit on the other side when a voltage is applied between electrode 101 and electrode 102. For example, injected into Fig. 3A the charge-generating layer 115 electrons into the light-emitting unit 106 and holes into the light-emitting unit 108 when a voltage is applied such that the potential of electrode 101 is higher than that of electrode 102.

[0212] It should be noted that, with regard to light extraction efficiency, the charge-generating layer 115 preferably transmits visible light (in particular, it has a visible light transmittance of 40% or higher). The charge-generating layer 115 functions even when it has a lower conductivity than the pair of electrodes (electrodes 101 and 102).

[0213] It should be noted that forming the charge-generating layer 115 using one of the aforementioned materials can suppress an increase in the drive voltage caused by the layer arrangement of the light-emitting layers.

[0214] The light-emitting element, which comprises two light-emitting units, is defined by Fig. 3A has been described; however, a similar structure can also be applied to a light-emitting element in which three or more light-emitting units are arranged one above the other. By using a plurality of light-emitting units separated from the charge-generating layer between a pair of electrodes, just as in light-emitting element 250, a light-emitting element can be provided that can emit light with high luminance while keeping the current density low and exhibiting a long lifetime. A light-emitting element with low power consumption can be provided.

[0215] If the structures described in embodiment 1 are used for at least one of the plurality of units, a light-emitting element with a high emission efficiency can be provided.

[0216] Preferably, the light-emitting layer 170 contained in the light-emitting unit 108 has a structure similar to that of the light-emitting layer 130 described in embodiment 1. In this case, the light-emitting element 250 has a high emission efficiency.

[0217] Furthermore, the light-emitting layer 120, which is contained in the light-emitting unit 106, contains a host material 121 and a guest material 122, as shown in Fig. Figure 3B is shown. It should be noted that guest material 122 is subsequently described as a fluorescent material. <<Lichtemissionsmechanismus der Licht emittierenden Schicht 120> >

[0218] The light emission mechanism of the light-emitting layer 120 is described below.

[0219] Excitons are formed when electrons and holes injected from the pair of electrodes (electrode 101 and electrode 102) or the charge-generating layer recombine in the light-emitting layer 120. Since the amount of host material 121 is greater than that of guest material 122, the host material 121 is excited by the exciton generation.

[0220] It should be noted that the term "exciton" refers to a charge carrier (electron and hole) pair. Since excitons possess energy, a material in which excitons are formed is brought into an excited state.

[0221] In the case where the excitation state formed of the host material 121 is a singlet excitation state, the singlet excitation energy is transferred from the S1 level of the host material 121 to the S1 level of the guest material 122, thereby forming the singlet excitation state of the guest material 122.

[0222] Since the guest material 122 is a fluorescent material, it emits light immediately upon the formation of a singlet excitation state. To achieve a high light emission efficiency in this case, the fluorescence quantum yield of the guest material 122 is preferably high. The same applies if a singlet excitation state is formed by recombination of charge carriers in the guest material 122.

[0223] Next, a case is described in which the recombination of charge carriers forms a triplet excitation state of the host material 121. The correlation of the energy levels of the host material 121 and the guest material 122 in this case is given in Fig. 3C shown. The following clarifies what terms and symbols in Fig. 3C. It should be noted that, since the T1 level of the host material 121 is preferably lower than the T1 level of the guest material 122, Fig. Figure 3C shows this preferable case. However, the T1 level of the host material 121 can be higher than the T1 level of the guest material 122. Host (121): the host material 121; Guest (122): the guest material 122 (the fluorescent material); S FH : the S1 level of host material 121; T FH : the T1 level of host material 121; S FG : the S1 level of guest material 122 (the fluorescent material); and T FG : the T1 level of guest material 122 (the fluorescent material).

[0224] As in Fig. As shown in 3C, a triplet-triplet annihilation (TTA) occurs; that is, triplet excitons formed by charge carrier recombination interact with each other, and an excitation energy is transferred, and spin angular momenta are exchanged; as a result, a reaction occurs in which the triplet excitons are converted into singlet excitons, which increase the energy of the S1 level of the host material 121 (S FH ) exhibit (see TTA in Fig. 3C). The singlet excitation energy of the host material 121 is determined by S FH to the S1 level of the guest material 122 (S FG ) transferred, which has a lower energy than S FH features (see Route E1 in Fig. 3C), and a singlet excitation state of the guest material 122 is formed, causing the guest material 122 to emit light.

[0225] It should be noted that in the case where the density of triplet excitons in the light-emitting layer 120 is sufficiently high (e.g. 1 × 10 -12 cm -3 or higher), only the response of two triplet excitons that are close together can be considered, whereas the deactivation of a single triplet exciton can be ignored.

[0226] In the case where a triplet excitation state of the guest material 122 is formed by charge carrier recombination, the triplet excitation energy of the guest material 122 is thermally deactivated, and it is difficult to use it for light emission. However, in the case where the T1 level of the host material 121 (T FH ) is lower than the T1 level of the guest material 122 (T FG ), the triplet excitation energy of the guest material 122 from the T1 level of the guest material 122 (T FG ) to the T1 level of host material 121 (T FH ) transferred (see Route E2 in Fig. 3C) and then used for TTA.

[0227] In other words, the host material 121 preferably has a function for converting the triplet excitation energy into singlet excitation energy by inducing TTA, so that the triplet excitation energy generated in the light-emitting layer 120 can be partially converted into singlet excitation energy in the host material 121 by TTA. The singlet excitation energy can be transferred to the guest material 122 and extracted as fluorescence. To achieve this effect, the S1 level of the host material 121 (S FH ) preferably higher than the S1 level of the guest material 122 (S FG ). Furthermore, the T1 level of the host material is 121 (T FH ) preferably lower than the T1 level of the guest material 122 (T FG ).

[0228] It should be noted that especially in the case where the T1 level of the guest material is 122 (T FG ) is lower than the T1 level of host material 121 (T FH ), the weight ratio of the guest material 122 to the host material 121 is preferably low. In particular, the weight ratio of the guest material 122 to the host material 121 is preferably greater than 0 and less than or equal to 0.05, in which case the probability of charge carrier recombination in the guest material 122 can be reduced. Furthermore, the probability of energy transfer from the T1 level of the host material 121 (T FH ) to the T1 level of the guest material 122 (T FG ) will be reduced.

[0229] It should be noted that the host material 121 can consist of a single compound or a multitude of compounds.

[0230] It should be noted that in each of the structures described above, the emission colors of the guest materials used in light-emitting unit 106 and light-emitting unit 108 can be the same or different. If the same guest materials, emitting light of the same color, are used for both light-emitting unit 106 and light-emitting unit 108, light-emitting element 250 can exhibit high emission luminance at a low current value, which is preferable. If guest materials emitting light of different colors are used for both light-emitting unit 106 and light-emitting unit 108, light-emitting element 250 can exhibit multicolored light emission, which is preferable.In this case, when a variety of light-emitting materials with different emission wavelengths are used in one or both of the light-emitting layers 120 and 170, the light-emitting element 250 emits light obtained by synthesizing lights with different emission peaks. That is to say, the emission spectrum of the light-emitting element 250 has at least two peaks.

[0231] The above structure is also suitable for obtaining white light emission. If the light-emitting layer 120 and the light-emitting layer 170 emit light of complementary colors, white light emission can be obtained. Particularly preferably, the guest materials are selected such that white light emission with high color rendering properties or light emission of at least red, green, and blue can be obtained.

[0232] One or both of the light-emitting layers 120 and 170 can be subdivided into layers, and the subdivided layers can each contain a different light-emitting material. That is, one or both of the light-emitting layers 120 and 170 can consist of two or more layers. For example, in the case where the light-emitting layer is formed by stacking a first light-emitting layer and a second light-emitting layer on top of each other in that order, starting from the hole-transport layer side, the first light-emitting layer is formed using a substance with hole-transport properties as its host material, and the second light-emitting layer is formed using a substance with electron-transport properties as its host material.In this case, a light-emitting material contained in the first light-emitting layer can be the same as, or different from, a light-emitting material contained in the second light-emitting layer. Furthermore, the materials can have the ability to emit light of the same color or light of different colors. White light emission with high color rendering, formed by three primary colors or four or more colors, can be obtained by using a variety of light-emitting materials that emit light of different colors.

[0233] In the case where the light-emitting units 106 and 108 contain guest materials with different emission colors, light emitted by the light-emitting layer 120 preferably exhibits an emission peak on the shorter wavelength side than light emitted by the light-emitting layer 170. Since the luminance of a light-emitting element using a material with a high triplet excitation energy level tends to degrade rapidly, TTA is used in the light-emitting layer emitting short-wavelength light, thus providing a light-emitting element with less luminance degradation. <Strukturbeispiel 2 des Licht emittierenden Elements>

[0234] Next, structural examples that differ from the light-emitting element described in will be presented. Fig. 3A to Fig. 3C is shown below using the following Fig. 4A to Fig. 4C described.

[0235] Fig. 4A is a schematic cross-sectional view of a light-emitting element 252.

[0236] The light-emitting element 252, which is in Fig. As shown in Figure 4A, an EL layer 110 is located between a pair of electrodes (electrode 101 and electrode 102). It should be noted that in the following description of the light-emitting element 252, electrode 101 serves as the anode and electrode 102 as the cathode; however, the functions of the light-emitting element 252 can be reversed.

[0237] The EL layer 110 comprises the light-emitting layer 180. The light-emitting layer 180 comprises the light-emitting layer 120 and the light-emitting layer 170. In the light-emitting element 252, the hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119 are shown as EL layer 110 in addition to the light-emitting layers. However, this stacked structure is an example, and the structure of the EL layer 110 in the light-emitting element 252 is not limited to it. For example, the arrangement order of the aforementioned layers of the EL layer 110 can be changed. Alternatively, another functional layer can be provided in the EL layer 110 in addition to the aforementioned layers.The functional layer may, for example, have a function to lower a hole or electron injection barrier, a function to improve a hole or electron transport property, a function to prevent the transport of holes or electrons, or a function to generate holes or electrons.

[0238] As in Fig. As shown in Figure 4B, the light-emitting layer 120 contains the host material 121 and the guest material 122. The light-emitting layer 170 contains a host material 171 and a guest material 172. The host material 171 contains an organic compound 171_1 and an organic compound 171_2. It should be noted that in the following description, the guest material 122 is a fluorescent material and the guest material 172 is a phosphorescent material. <<Lichtemissionsmechanismus der Licht emittierenden Schicht 180> >

[0239] The light emission mechanism of the light-emitting layer 120 is similar to that of the light-emitting layer 120 described in Fig. 3A to Fig. Figure 3C illustrates the light emission mechanism of the light-emitting layer 170. This mechanism is similar to that of the light-emitting layer 130 of embodiment 1. In other words, the host material 171, the organic compound 171_1, the organic compound 171_2, and the guest material 172 are similar to the host material 131, the organic compound 131_1, the organic compound 131_2, and the guest material 132, respectively.

[0240] As with the light-emitting element 252, in the case where the light-emitting layers 120 and 170 are in contact with each other, even if energy is transferred from the exciplex to the host material 121 of the light-emitting layer 120 at an interface between the light-emitting layer 120 and the light-emitting layer 170 (especially if triplet excitation level energy is transferred), triplet excitation energy can be converted into light emission in the light-emitting layer 120.

[0241] The T1 level of the host material 121 of the light-emitting layer 120 is preferably lower than the T1 levels of the organic compounds 171_1 and 171_2 of the light-emitting layer 170. In the light-emitting layer 120, the S1 level of the host material 121 is preferably higher than the S1 level of the guest material 122 (the fluorescent material), whereas the T1 level of the host material 121 is preferably lower than the T1 level of the guest material 122 (the fluorescent material).

[0242] Fig. 4C shows a correlation of energy levels using TTA in light-emitting layer 120 and ExTET in light-emitting layer 170. The following clarifies what terms and symbols in Fig. Represent 4C: Fluorescence-EML (120): the light-emitting layer 120 (the fluorescent light-emitting layer); Phosphorescent EML (170): the light-emitting layer 170 (the phosphorescent light-emitting layer); Host (121): the host material 121; Guest (122): the guest material 122 (the fluorescent material); Host (171_1): the host material (the organic compound 171_1); Guest (172): the guest material 172 (the phosphorescent material); Exciplex: an Exciplex (organic compound 171_1 and organic compound 171_2); S FH : the S1 level of host material 121; T FH : the T1 level of host material 121; S FG : the S1 level of guest material 122 (the fluorescent material); T FG : the T1 level of guest material 122 (the fluorescent material); S PH : the S1 level of the host material (of the organic compound 171_1); T PH : the T1 level of the host material (of the organic compound 171_1); T PG : the T1 level of the guest material 172 (the phosphorescent material); S E : the S1 level of the exciplex; and T E : the T1 level of the exciplex.

[0243] As in Fig. As shown in Figure 4C, the exciplex exists in only one excited state; therefore, exciton diffusion between exciplexes is less likely. Furthermore, energy diffusion from the exciplex into organic compound 171_1 does not occur because the excitation energy levels (S E and T E ) of the exciplex are lower than the excitation energy levels (S PH and T PH ) of the organic compound 171_1 (of the host material of the phosphorescent material) of the light-emitting layer 170. This means that the efficiency of the phosphorescent light-emitting layer (of the light-emitting layer 170) can be maintained because an exciton diffusion length of the exciplex in the phosphorescent light-emitting layer (of the light-emitting layer 170) is short.Furthermore, the energy loss can be reduced even if some of the triplet excitation energy of the exciplex of the phosphorescent light-emitting layer (the light-emitting layer 170) diffuses into the fluorescent light-emitting layer (the light-emitting layer 120) through the interface between the fluorescent light-emitting layer (the light-emitting layer 120) and the phosphorescent light-emitting layer (the light-emitting layer 170), because the triplet excitation energy in the fluorescent light-emitting layer (the light-emitting layer 120) generated by the diffusion is converted into light emission by TTA.

[0244] The light-emitting element 252 can exhibit high emission efficiency because ExTET is used in the light-emitting layer 170 and TTA is used in the light-emitting layer 120, as described above, thus reducing energy loss. As with the light-emitting element 252, in addition to reducing energy loss, the number of EL layers 110 can be reduced when the light-emitting layer 120 and the light-emitting layer 170 are in contact with each other. Therefore, a light-emitting element with low manufacturing costs can be obtained.

[0245] It should be noted that the light-emitting layer 120 and the light-emitting layer 170 are not necessarily in contact with each other. In this case, it is possible to prevent energy transfer via the Dexter mechanism (in particular, triplet energy transfer) from the organic compound 171_1 in an excited state, the organic compound 171_2 in an excited state, or the guest material 172 (the phosphorescent material) in an excited state generated in the light-emitting layer 170, to the host material 121 or the guest material 122 (the fluorescent material) in the light-emitting layer 120. Therefore, the thickness of a layer provided between the light-emitting layer 120 and the light-emitting layer 170 can be a few nanometers.In particular, the thickness is preferably more than or equal to 1 nm and less than or equal to 5 nm, whereby an increase in the driving voltage can be prevented.

[0246] The layer provided between light-emitting layer 120 and light-emitting layer 170 can contain a single material or both a hole transport material and an electron transport material. In the case of a single material, a bipolar material can be used. Here, bipolar refers to a material in which the ratio between electron mobility and hole mobility is 100 or less. Alternatively, the hole transport material, the electron transport material, or the like can be used. At least one of the materials contained in the layer can be identical to the host material (organic compound 171_1 or 171_2) of light-emitting layer 170. This promotes the production of the light-emitting element and reduces the drive voltage.Furthermore, the hole transport material and the electron transport material can form an exciplex that effectively prevents exciton diffusion. In particular, it is possible to prevent energy transfer from the host material (the organic compound 171_1 or 171_2) in an excited state or from the guest material 172 (the phosphorescent material) in an excited state of the light-emitting layer 170 to the host material 121 or the guest material 122 (the fluorescent material) in the light-emitting layer 120.

[0247] In the case of the light-emitting element 252, although the light-emitting layer 170 and the light-emitting layer 120 have been described as being located on the side of the hole transport layer 112 and on the side of the electron transport layer 118, respectively, the light-emitting element of one embodiment of the present invention is not limited to this structure. The light-emitting layer 170 and the light-emitting layer 120 can be located on the side of the electron transport layer 118 and on the side of the hole transport layer 112, respectively.

[0248] It should be noted that in the light-emitting element 252, a charge carrier recombination region is preferably distributed to a certain extent. Therefore, the light-emitting layer 120 or 170 preferably exhibits an appropriate degree of charge carrier trapping property. Particularly preferably, the guest material 172 (the phosphorescent material) in the light-emitting layer 170 exhibits hole trapping property. Therefore, the structure of the light-emitting layer 130 of embodiment 1 is suitable for that of the light-emitting layer 170.

[0249] It should be noted that light emitted by the light-emitting layer 120 preferably has an emission peak on the shorter wavelength side than light emitted by the light-emitting layer 170. Since the luminance of a light-emitting element using a phosphorescent material emitting short-wavelength light tends to degrade rapidly, short-wavelength fluorescence is employed to provide a light-emitting element with less luminance degradation.

[0250] Furthermore, the light-emitting layer 120 and the light-emitting layer 170 can be configured to emit light with different emission wavelengths, so that the light-emitting element can be a multicolored light-emitting element. In this case, the emission spectrum of the light-emitting element is formed by combining light with different emission peaks and therefore has at least two peaks.

[0251] The above structure is also suitable for obtaining white light emission. If light-emitting layer 120 and light-emitting layer 170 emit light of complementary colors, white light emission can be obtained.

[0252] Furthermore, a white light emission with high color rendering properties can be obtained, formed by three primary colors or four or more colors, by using a variety of light-emitting materials emitting light of different emission wavelengths for one or both of the light-emitting layers 120 and 170. In this case, the light-emitting layer can be divided into layers, and each of the divided layers can contain a light-emitting material that differs from the others. <Material, das bei den Licht emittierenden Schichten verwendet werden kann>

[0253] Next, materials that can be used in the light-emitting layers 120 and 170 are described. <<Material, das bei der Licht emittierenden Schicht 120 verwendet werden kann> >

[0254] In the light-emitting layer 120, the host material 121 is present in the highest weight fraction, and the guest material 122 (the fluorescent material) is dispersed in the host material 121. The S1 level of the host material 121 is preferably higher than the S1 level of the guest material 122 (the fluorescent material), whereas the T1 level of the host material 121 is preferably lower than the T1 level of the guest material 122 (the fluorescent material).

[0255] In the light-emitting layer 120, the guest material 122 is preferably, but not limited to, an anthracene derivative, a tetracene derivative, a chrysene derivative, a phenanthrene derivative, a pyrene derivative, a perylene derivative, a stilbene derivative, an acridone derivative, a coumarin derivative, a phenoxazine derivative, a phenothiazine derivative or the like, and one of the following materials may be used, for example.

[0256] The examples include 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (Abbreviation: 1,6FLPAPrn), N,N'-Bis(3-methylphenyl)-N,N-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (Abbreviation: 1,6mMemFLPAPrn), N,N'-Bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,IV'-bis(4-tert-butylphenyl)pyrene-1,6-diamine (Abbreviation: 1,6tBu-FLPAPrn), N,N'-Diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-3,8-dicyclohexylpyrene-1,6-diamine (Abbreviation: ch-1,6FLPAPrn), 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: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N,N,N',N',N'',N''-octaphenyldibenzo[g,p]chrysen-2,7,10,15-tetraamine (Abbreviation: DBC1), Coumarin 30, N-(9,10-Diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (Abbreviation: 2PCAPA), N-[9,10-bis(1,1'-Biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (Abbreviation: 2PCABPhA), N-(9,10-Diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (Abbreviation: 2DPAPA), N-[9,10-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (Abbreviation: 2DPABPhA), 9,10-Bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracene-2-amine (Abbreviation: 2YGABPhA), N,N,9-Triphenylanthracene-9-amine (Abbreviation: DPhAPhA), Coumarin 6, Coumarin 545T, N,N'-Diphenylquinacridone (Abbreviation: DPQd), Rubrene, 2,8-Di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (Abbreviation: TBRb), Nile Red, 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)propanenitrile (Abbreviation: DCM1), 2-{2-Methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[lj]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (Abbreviation: DCM2), N,N,N',N-Tetrakis(4-methylphenyl)tetracene-5,11-diamine (Abbreviation: p-mPhTD), 7,14-Diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (Abbreviation: p-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[lj]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]quinolizine} -9-yl)ethenyl]-4H-pyran-4-ylidene}propanenitrile (abbreviation: BisDCJTM) and 5,10,15,20-Tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene.

[0257] Although there is no particular restriction regarding a material that can be used as host material 121 in the light-emitting layer 120, any of the following materials, for example, can be used: metal complexes, such as... B. Tris(8-quinolinolato)aluminium(III) (abbreviation: Alq), Tris(4-methyl-8-quinolinolato)aluminium(III) (abbreviation: Almq3), Bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), Bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminium(III) (abbreviation: BAlq), Bis(8-quinolinolato)zinc(II) (abbreviation: Znq), Bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and Bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ); heterocyclic compounds, such as... B. 2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-Bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 3-(4-Biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 2,2',2''-(1,3,5-Benzenetriyl)-tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP) and 9-[4-(5-Phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11); and aromatic amine compounds, such as... Examples include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), and 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB). Additionally, condensed polycyclic aromatic compounds, such as... B. Anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives and dibenzo[g,p]chrysene derivatives are specified, and specific examples include 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA),4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), N,9-Diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N,9-diphenyl-N-(9,10-diphenyl-2-anthryl)-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-Dimethoxy-5,11-diphenylchrysene, N,N,N,N,N',N',N',N'',N''-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetramine (abbreviation: DBC1), 9-[4-(10-Phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 3,6-Diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 9,10-Bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-Di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-Butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-Bianthryl (abbreviation: BANT), 9,9'-(Stilben-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(Stilben-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-Tri(1-pyrenyl)benzene (abbreviation: TPB3) and the like. One or more substances with a larger energy gap than guest material 122 are preferably selected from these substances and known substances.

[0258] The light-emitting layer 120 can have a structure in which two or more layers are arranged one above the other. In the case where, for example, the light-emitting layer 120 is formed by arranging a first light-emitting layer and a second light-emitting layer on top of each other in that order from the side of the hole transport layer, the first light-emitting layer is formed using a substance with a hole transport property as the host material, and the second light-emitting layer is formed using a substance with an electron transport property as the host material.

[0259] In the light-emitting layer 120, the host material 121 can consist of one type of compound or a variety of compounds. Alternatively, the light-emitting layer 120 can contain a different material than the host material 121 and the guest material 122. <<Material, das in der Licht emittierenden Schicht 170 verwendet werden kann> >

[0260] A material suitable for use in the light-emitting layer 170 can be the same material used in the light-emitting layer 130 of embodiment 1. This allows the production of a light-emitting element with high emission efficiency.

[0261] There is no restriction regarding the emission colors of the light-emitting materials contained in the light-emitting layers 120 and 170, and they can be the same or different. Light emitted by the light-emitting materials is mixed and extracted from the element; therefore, for example, if their emission colors are complementary, the light-emitting element can emit white light. Considering the reliability of the light-emitting element, the emission peak wavelength of the light-emitting material contained in the light-emitting layer 120 is preferably shorter than that of the light-emitting material contained in the light-emitting layer 170.

[0262] It should be noted that the light-emitting units 106 and 108 and the charge-generating layer 115 can be formed by an evaporation process (including a vacuum evaporation process), an inkjet process, a coating process, gravure printing or the like.

[0263] The structure described above for this embodiment can be used in a suitable combination with any of the structures described for the other embodiments. (Version 3)

[0264] In this embodiment, examples of light-emitting elements with structures that differ from those described in embodiments 1 and 2 are given below, based on Fig. 5A and Fig. 5B, Fig. 6A and Fig. 6B, Fig. 7A to Fig. 7C and Fig. 8A to Fig. 8C described. <Strukturbeispiel 1 des Licht emittierenden Elements>

[0265] Fig. 5A and Fig. Figure 5B are cross-sectional views, each representing a light-emitting element of an embodiment of the present invention. Fig. 5A and Fig. In some cases, 5B is a section with a similar function to the one in Fig. 1A through the same hatching pattern as in Fig. Sections are shown in 1A and are not specifically marked with a reference symbol. Furthermore, the same reference symbols are used for sections with similar functions, and a detailed description of the sections is omitted in some cases.

[0266] Light-emitting elements 260a and 260b in Fig. 5A and Fig. 5B can have a bottom-emission structure in which light is extracted via the substrate 200, or they can have a top-emission structure in which light emitted by the light-emitting element is extracted in the direction opposite the substrate 200. However, an embodiment of the present invention is not limited to this structure, and a light-emitting element with a dual-emission structure in which light emitted by the light-emitting element is extracted in both the top and bottom directions of the substrate 200 can be used.

[0267] In the case where the light-emitting elements 260a and 260b each have a bottom-emission structure, the electrode 101 preferably has a light-transmitting function and the electrode 102 preferably has a light-reflecting function. Alternatively, in the case where the light-emitting elements 260a and 260b each have a top-emission structure, the electrode 101 preferably has a light-reflecting function and the electrode 102 preferably has a light-transmitting function.

[0268] The light-emitting elements 260a and 260b each comprise electrode 101 and electrode 102 above substrate 200. Between electrodes 101 and 102, a light-emitting layer 123B, a light-emitting layer 123G, and a light-emitting layer 123R are provided. The hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119 are also provided.

[0269] The light-emitting element 260b comprises, as part of the electrode 101, a conductive layer 101a, a conductive layer 101b above the conductive layer 101a, and a conductive layer 101c below the conductive layer 101a. In other words, the light-emitting element 260b comprises the electrode 101 with a structure in which the conductive layer 101a is arranged between the conductive layer 101b and the conductive layer 101c.

[0270] In the light-emitting element 260b, the conductive layer 101b and the conductive layer 101c can be formed from different materials or from the same material. The electrode 101 preferably has a structure in which the conductive layer 101a is arranged between the layers formed from the same conductive material, in which case structuring by etching can be easily carried out in the process for forming the electrode 101.

[0271] In the light-emitting element 260b, the electrode 101 can comprise either the conductive layer 101b or the conductive layer 101c.

[0272] For each of the conductive layers 101a, 101b and 101c contained in the electrode 101, the structure and materials of the electrode 101 or 102 described in embodiment 1 can be used.

[0273] In Fig. 5A and Fig. 5B is a partition 145 provided between a region 221B, a region 221G, and a region 221R, which are arranged between electrode 101 and electrode 102. The partition 145 has insulating properties. The partition 145 covers end sections of electrode 101 and has openings that overlap the electrode. The partition 145 allows the electrode 101, which is provided above the substrate 200 in the regions, to be divided into island shapes.

[0274] It should be noted that the light-emitting layer 123B and the light-emitting layer 123G can overlap each other in an area where they overlap the partition 145. The light-emitting layer 123G and the light-emitting layer 123R can overlap each other in an area where they overlap the partition 145. The light-emitting layer 123R and the light-emitting layer 123B can overlap each other in an area where they overlap the partition 145.

[0275] The partition 145 has insulating properties and is formed using an inorganic or organic material. Examples of inorganic materials include silicon dioxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, and aluminum nitride. Examples of organic materials include photosensitive resin materials, such as acrylic resins and polyimide resins.

[0276] It should be noted that a silicon oxynitride film refers to a film in which the proportion of oxygen is higher than that of nitrogen. The silicon oxynitride film preferably contains oxygen, nitrogen, silicon, and hydrogen in the ranges of 55 atomic percent to 65 atomic percent, 1 atomic percent to 20 atomic percent, 25 atomic percent to 35 atomic percent, and 0.1 atomic percent to 10 atomic percent, respectively. A silicon nitride oxide film refers to a film in which the proportion of nitrogen is higher than that of oxygen. The silicon nitride oxide film preferably contains nitrogen, oxygen, silicon, and hydrogen in the ranges of 55 atomic percent to 65 atomic percent, 1 atomic percent to 20 atomic percent, 25 atomic percent to 35 atomic percent, and 0.1 atomic percent to 10 atomic percent, respectively.

[0277] The light-emitting layers 123R, 123G, and 123B preferably contain light-emitting materials with functions for emitting light of different colors. For example, if light-emitting layer 123R has a light-emitting material with a function for emitting red, region 221R emits red light. If light-emitting layer 123G has a light-emitting material with a function for emitting green, region 221G emits green light. If light-emitting layer 123B has a light-emitting material with a function for emitting blue, region 221B emits blue light. The light-emitting element 260a or 260b with such a structure is used in a pixel of a display device, thereby enabling the production of a full-color display device. The thicknesses of the light-emitting layers can be the same or different from one another.

[0278] One or more of the light-emitting layer 123B, the light-emitting layer 123G, and the light-emitting layer 123R preferably have a structure similar to that of the light-emitting layer 130 described in embodiment 1. In this case, a light-emitting element with high emission efficiency can be produced.

[0279] One or more of the light-emitting layers 123B, 123G and 123R may comprise two or more layers arranged on top of each other.

[0280] If at least one light-emitting layer, as described above, has the structure of the light-emitting layer described in embodiments 1 and 2, and the light-emitting element 260a or 260b comprising the light-emitting layer is used in pixels in a display device, a display device with high emission efficiency can be manufactured. The display device comprising the light-emitting element 260a or 260b can thus have reduced power consumption.

[0281] By providing an optical element (e.g., a color filter, a polarizing plate, and an anti-reflective film) on the light extraction side of the electrode, the color purity of each of the light-emitting elements 260a and 260b can be improved. Consequently, the color purity of a display device comprising light-emitting element 260a or 260b can be improved. Alternatively, the reflection of external light from each of the light-emitting elements 260a and 260b can be reduced. Consequently, the contrast ratio of a display device comprising light-emitting element 260a or 260b can be improved.

[0282] For the other components of the light-emitting elements 260a and 260b, reference can be made to the components of the light-emitting element in embodiments 1 and 2. <Strukturbeispiel 2 des Licht emittierenden Elements>

[0283] Next, structural examples that differ from the light-emitting elements described in will be presented. Fig. 5A and Fig. 5B are shown below using the following Fig. 6A and Fig. 6B described.

[0284] Fig. 6A and Fig. Figure 6B shows cross-sectional views of a light-emitting element of an embodiment of the present invention. Fig. 6A and Fig. In some cases, section 6B has a similar function to the one in Fig. 5A and Fig. 5B through the same hatching pattern as in Fig. 5A and Fig. 5B is shown and not specifically marked with a reference symbol. Furthermore, the same reference symbols are used for sections with similar functions, and a detailed description of such sections is omitted in some cases.

[0285] Fig. 6A and Fig. Figure 6B presents structural examples of a light-emitting element comprising the light-emitting layer between a pair of electrodes. A light-emitting element 262a, which is in Fig. 6A shows a top-emission structure in which light is extracted in a direction opposite the substrate 200, and a light-emitting element 262b which is in Fig. Figure 6B shows a bottom-emission structure in which light is extracted towards the side of the substrate 200. However, an embodiment of the present invention is not limited to these structures and may have a dual-emission structure in which light extracted from the light-emitting element is extracted in both the top and bottom directions with respect to the substrate 200 above which the light-emitting element is formed.

[0286] The light-emitting elements 262a and 262b each comprise electrode 101, electrode 102, electrode 103, and electrode 104 above substrate 200. At least one light-emitting layer 170, one light-emitting layer 190, and one charge-generating layer 115 are provided between electrode 101 and electrode 102, between electrode 102 and electrode 103, and between electrode 102 and electrode 104. The hole injection layer 111, the hole transport layer 112, the electron transport layer 113, the electron injection layer 114, the hole injection layer 116, the hole transport layer 117, the electron transport layer 118, and the electron injection layer 119 are also provided.

[0287] Electrode 101 comprises a conductive layer 101a and a conductive layer 101b above and in contact with the conductive layer 101a. Electrode 103 comprises a conductive layer 103a and a conductive layer 103b above and in contact with the conductive layer 103a. Electrode 104 comprises a conductive layer 104a and a conductive layer 104b above and in contact with the conductive layer 104a.

[0288] The light-emitting element 262a, which is in Fig. 6A is shown, and the light-emitting element 262b, which is in Fig. As shown in Figure 6B, each section comprises a partition 145 between a region 222B located between electrode 101 and electrode 102, a region 222G located between electrode 102 and electrode 103, and a region 222R located between electrode 102 and electrode 104. The partition 145 has insulating properties. The partition 145 covers end sections of electrodes 101, 103, and 104 and has openings that overlap the electrodes. The partition 145 allows the electrodes, which are provided above the substrate 200 in the regions, to be divided into island shapes.

[0289] The charge-generating layer 115 can be formed with a material obtained by adding an electron acceptor to a hole transport material, or with a material obtained by adding an electron donor to an electron transport material. It should be noted that if the conductivity of the charge-generating layer 115 is as high as that of the electrode pair, the charge carriers generated in the charge-generating layer 115 could migrate to a neighboring pixel, potentially causing light emission in that pixel. To avoid such distorted light emission from a neighboring pixel, the charge-generating layer 115 is preferably formed with a material whose conductivity is lower than that of the electrode pair.

[0290] The light-emitting elements 262a and 262b each comprise a substrate 220 provided with an optical element 224B, an optical element 224G, and an optical element 224R in the direction in which light emitted from area 222B, light emitted from area 222G, and light emitted from area 222R are extracted. Light emitted from each area is emitted to the outside of the light-emitting element via each optical element. In other words, the light from area 222B, the light from area 222G, and the light from area 222R are emitted via optical element 224B, optical element 224G, and optical element 224R, respectively.

[0291] Optical elements 224B, 224G, and 224R each have a function for selectively transmitting light of a specific color from the incident light. For example, the light emitted from area 222B via optical element 224B is blue light, the light emitted from area 222G via optical element 224G is green light, and the light emitted from area 222R via optical element 224R is red light.

[0292] For example, a color layer (also called a color filter), a bandpass filter, a multilayer filter, or the like can be used for the optical elements 224R, 224G, and 224B. Alternatively, color conversion elements can be used as optical elements. A color conversion element is an optical element that converts incident light into light with a longer wavelength than the incident light. Quantum dot elements can be advantageously used as color conversion elements. The use of quantum dots can increase the color reproducibility of the display device.

[0293] One or more optical elements may be arranged over each of the optical elements 224R, 224G, and 224B. An additional optical element may be, for example, a circularly polarizing plate, an antireflection film, or the like. A circularly polarizing plate placed on the side from which light emitted by the light-emitting element of the display device is extracted can prevent a phenomenon in which light incident from the outside of the display device is reflected within the display device and directed back outwards. An antireflection film can attenuate external light reflected from a surface of the display device. This results in a clear observation of light emitted by the display device.

[0294] It should be noted that in Fig. 6A and Fig. 6B Blue light (B), green light (G) and red light (R) emitted from the areas via the optical elements are schematically represented by arrows made of dashed lines.

[0295] An opaque layer 223 is provided between the optical elements. The opaque layer 223 serves to block light emitted from adjacent areas. It should be noted that a structure without the opaque layer 223 can also be used.

[0296] The opaque layer 223 has the function of reducing the reflection of external light. The opaque layer 223 also has the function of preventing the mixing of light emitted by a neighboring light-emitting element. The opaque layer 223 can be a metal, a resin containing a black pigment, carbon black, a metal oxide, a composite oxide containing a solid solution of a variety of metal oxides, or the like.

[0297] It should be noted that optical element 224B and optical element 224G can overlap in an area where they overlap the opaque layer 223. Furthermore, optical element 224G and optical element 224R can overlap in an area where they overlap the opaque layer 223. Additionally, optical element 224R and optical element 224B can overlap in an area where they overlap the opaque layer 223.

[0298] For the structures of substrate 200 and substrate 220, which are provided with the optical elements, reference can be made to embodiment 1.

[0299] Furthermore, the light-emitting elements 262a and 262b have a microcavity structure. <<Mikrokavitätsstruktur> >

[0300] Light emitted by light-emitting layer 170 and light-emitting layer 190 oscillates between a pair of electrodes (e.g., electrode 101 and electrode 102). Light-emitting layer 170 and light-emitting layer 190 are positioned such that they amplify light of a desired wavelength among the light to be emitted. For example, by adjusting the optical length from a reflective region of electrode 101 to the light-emitting region of light-emitting layer 170, and the optical length from a reflective region of electrode 102 to the light-emitting region of light-emitting layer 170, the light of a desired wavelength can be amplified among the light emitted by light-emitting layer 170.By adjusting the optical length from the reflective area of ​​electrode 101 to the light-emitting area of ​​the light-emitting layer 190, as well as the optical length from the reflective area of ​​electrode 102 to the light-emitting area of ​​the light-emitting layer 190, the light of a desired wavelength can be amplified from the light emitted by the light-emitting layer 190. In the case of a light-emitting element in which a plurality of light-emitting layers (here, the light-emitting layers 170 and 190) are arranged one above the other, the optical lengths of the light-emitting layers 170 and 190 are preferably optimized.

[0301] In each of the light-emitting elements 262a and 262b, the amount of light of a desired wavelength can be increased below the amount of light emitted by the light-emitting layers 170 and 190 by adjusting the thicknesses of the conductive layers (conductive layer 101b, conductive layer 103b, and conductive layer 104b) in each region. It should be noted that the thickness(es) of the hole injection layer 111 and / or the hole transport layer 112 can differ between the regions to increase the amount of light emitted by the light-emitting layers 170 and 190.

[0302] For example, in the case where the refractive index of the conductive material with a function for reflecting light in the electrodes 101 to 104 is lower than the refractive index of the light-emitting layer 170 or 190, the thickness of the conductive layer 101b of the electrode 101 is adjusted such that the optical length between the electrode 101 and the electrode 102 is reduced to m B λ B / 2 will (m B is a natural number and λ B (is the wavelength of the light that is amplified in the region 222B). The thickness of the conductive layer 103b of the electrode 103 is similarly adjusted such that the optical length between the electrode 103 and the electrode 102 is m G λ G / 2 will (m G is a natural number and λ G (is the wavelength of the light that is amplified in the region 222G). Furthermore, the thickness of the conductive layer 104b of the electrode 104 is adjusted such that the optical length between the electrode 104 and the electrode 102 is m R λ R / 2 will be (m R is a natural number and λ R is the wavelength of the light that is amplified in the 222R range).

[0303] In cases where it is difficult to precisely determine the reflective areas of electrodes 101 to 104, the optical length for increasing the intensity of the light emitted by light-emitting layer 170 or light-emitting layer 190 can be derived by assuming that certain areas of electrodes 101 to 104 are the reflective areas. Similarly, in cases where it is difficult to precisely determine the light-emitting areas of light-emitting layer 170 and light-emitting layer 190, the optical length for increasing the intensity of the light emitted by light-emitting layer 170 and light-emitting layer 190 can be derived by assuming that certain areas of light-emitting layer 170 and light-emitting layer 190 are the light-emitting areas.

[0304] In the above manner, the microcavity structure, in which the optical length between the pair of electrodes is adjusted in the respective areas, can suppress scattering and absorption of light in the vicinity of the electrodes, resulting in high light extraction efficiency.

[0305] In the above structure, the conductive layers 101b, 103b, and 104b preferably have a light-transmitting function. The materials for the conductive layers 101b, 103b, and 104b can be the same or different. Preferably, the same material is used for the conductive layer 101b, the conductive layer 103b, and the conductive layer 104b, since structuring by etching can be easily carried out during the formation process of the electrode 101, the electrode 103, and the electrode 104. Each of the conductive layers 101b, 103b, and 104b can have a multilayer structure consisting of two or more layers.

[0306] Since the light-emitting element 262a, which is in Fig. As shown in Figure 6A, which has a top-emission structure, the conductive layer 101a, the conductive layer 103a and the conductive layer 104a have a light-reflecting function. Furthermore, the electrode 102 preferably has light-transmitting and light-reflecting functions.

[0307] Since the light-emitting element 262b, which is in Fig. Figure 6B shows a bottom-emission structure, and the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a preferably have functions for transmitting and reflecting light. Furthermore, the electrode 102 preferably has a function for reflecting light.

[0308] In each of the light-emitting elements 262a and 262b, the conductive layers 101a, 103a, and 104a can be formed from different materials or from the same material. If the conductive layers 101a, 103a, and 104a are formed from the same material, the manufacturing costs of the light-emitting elements 262a and 262b can be reduced. It should be noted that each of the conductive layers 101a, 103a, and 104a can have a multilayer structure consisting of two or more layers.

[0309] At least one of the structures described in embodiments 1 and 2 is preferably used for at least one of the light-emitting layers 170 and 190 contained in the light-emitting elements 262a and 262b. In this way, the light-emitting elements can have a high emission efficiency.

[0310] One or both of the light-emitting layers 170 and 190 can, like the light-emitting layers 190a and 190b, for example, have a multilayer structure consisting of two layers. The two light-emitting layers, each containing two types of light-emitting materials (a first compound and a second compound) for emitting light of different colors, enable the emission of light in a variety of colors. Preferably, the light-emitting materials of the light-emitting layers are selected such that white light can be obtained by combining the light emissions from the light-emitting layers 170 and 190.

[0311] One or both of the light-emitting layers 170 and 190 may have a multilayer structure consisting of three or more layers, which may include one layer that does not contain light-emitting material.

[0312] By using the light-emitting element 262a or 262b, which has at least one of the structures of the light-emitting layers described in embodiments 1 and 2, in pixels of a display device, a display device with high emission efficiency can be produced in the manner described above. The display device comprising the light-emitting element 262a or 262b can thus have reduced power consumption.

[0313] For the other components of the light-emitting elements 262a and 262b, reference can be made to the components of the light-emitting element 260a or 260b or of the light-emitting element of embodiment 1 or 2. <Herstellungsverfahren des Licht emittierenden Elements>

[0314] Next, a method for manufacturing a light-emitting element of an embodiment of the present invention will be described below using the following examples: Fig. 7A to Fig. 7C and Fig. 8A to Fig. 8C is described here. A method for producing the light-emitting element 262a, which is described in Fig. 6A is shown and described.

[0315] Fig. 7A to Fig. 7C and Fig. 8A to Fig. Figure 8C are cross-sectional views illustrating a method for manufacturing the light-emitting element of an embodiment of the present invention.

[0316] The following described procedure for producing the light-emitting element 262a comprises a first to seventh step. <<Erster Schritt> >

[0317] In the first step, the electrodes (in particular the conductive layer 101a of electrode 101, the conductive layer 103a of electrode 103 and the conductive layer 104a of electrode 104) of the light-emitting elements are formed over the substrate 200 (see Fig. 7A).

[0318] In this embodiment, a conductive layer with a light-reflecting function is formed over the substrate 200 and processed into a desired shape, thereby forming the conductive layers 101a, 103a, and 104a. An alloy film of silver, palladium, and copper (also known as an Ag-Pd-Cu film or APC) is used as the conductive layer with a light-reflecting function. The conductive layers 101a, 103a, and 104a are preferably formed in a single step for processing the same conductive layer, as this reduces manufacturing costs.

[0319] It should be noted that a large number of transistors can be formed above substrate 200 before the first step. These transistors can be electrically connected to the conductive layers 101a, 103a, and 104a. <<Zweiter Schritt> >

[0320] In the second step, the conductive layer 101b is formed with a function for transmitting light over the conductive layer 101a of the electrode 101, the conductive layer 103b is formed with a function for transmitting light over the conductive layer 103a of the electrode 103, and the conductive layer 104b is formed with a function for transmitting light over the conductive layer 104a of the electrode 104 (see Fig. 7B).

[0321] In this embodiment, the conductive layers 101b, 103b, and 104b, each having a function for transmitting light, are formed over the conductive layers 101a, 103a, and 104a, each having a function for reflecting light, thereby forming electrode 101, electrode 103, and electrode 104. ITSO films are used as the conductive layers 101b, 103b, and 104b.

[0322] The conductive layers 101b, 103b, and 104b, which have a light-transmitting function, can be formed in a variety of steps. When these conductive layers are formed in a variety of steps, they can be designed to have thicknesses that allow for suitable microcavity structures in the respective regions. <<Dritter Schritt> >

[0323] In the third step, the partition 145, which covers the end sections of the electrodes of the light-emitting element, is formed (see Fig. 7C).

[0324] The partition 145 has an opening that overlaps the electrode. The conductive film exposed through the opening serves as the anode of the light-emitting element. In this embodiment, a polyimide-based resin is used as the partition 145.

[0325] In the first to third steps, various film formation processes and micromachining techniques can be employed, as there is no possibility of damaging the EL layer (a layer containing an organic compound). In this embodiment, a reflective conductive layer is formed by a sputtering process, a pattern is formed over the conductive layer by a lithography process, and then the conductive layer is processed into an island shape by a dry or wet etching process to form the conductive layer 101a of electrode 101, the conductive layer 103a of electrode 103, and the conductive layer 104a of electrode 104.Then a transparent conductive film is formed by a sputtering process, a pattern is formed over the transparent conductive film by a lithography process, and then the transparent conductive film is processed into an island shape by a wet etching process to form the electrodes 101, 103 and 104. <<Vierter Schritt> >

[0326] In the fourth step, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 190, the electron transport layer 113, the electron injection layer 114 and the charge generation layer 115 are formed (see Fig. 8A).

[0327] The hole injection layer 111 can be formed by co-evaporation of a hole transport material and a material containing an acceptor substance. It should be noted that a co-evaporation process is an evaporation process in which a variety of different substances are evaporated simultaneously from different evaporation sources. The hole transport layer 112 can be formed by evaporation of a hole transport material.

[0328] The light-emitting layer 190 can be formed by evaporating a guest material that emits light of at least one color selected from violet, blue, blue-green, green, yellow-green, yellow, orange, and red. A fluorescent or phosphorescent organic material can be used as the guest material. The structure of the light-emitting layer described in embodiment 1 or 2 is preferably employed. The light-emitting layer 190 can have a two-layer structure. In such a case, the two light-emitting layers preferably contain light-emitting materials that emit light of different colors.

[0329] The electron transport layer 113 can be formed by evaporating a substance with high electron transport properties. The electron injection layer 114 can be formed by evaporating a substance with high electron injection properties.

[0330] The charge-generating layer 115 can be formed by evaporating a material obtained by adding an electron acceptor (acceptor) to a hole transport material, or a material obtained by adding an electron donor (donor) to an electron transport material. <<Fünfter Schritt> >

[0331] In the fifth step, the hole injection layer 116, the hole transport layer 117, the light-emitting layer 170, the electron transport layer 118, the electron injection layer 119 and the electrode 102 are formed (see Fig. 8B).

[0332] The hole injection layer 116 can be formed using a material and a process similar to those of the hole injection layer 111. The hole transport layer 117 can be formed using a material and a process similar to those of the hole transport layer 112.

[0333] The light-emitting layer 170 can be formed by evaporating a guest material that emits light of at least one color selected from violet, blue, blue-green, green, yellow-green, yellow, orange, and red. A fluorescent or phosphorescent organic compound can be used as the guest material. The structure of the light-emitting layer described in embodiment 1 or 2 is preferably employed. It should be noted that the light-emitting layer 170 and / or the light-emitting layer 190 preferably have the structure of a light-emitting layer described in embodiment 1. The light-emitting layer 170 and the light-emitting layer 190 preferably contain light-emitting organic compounds that emit light of different colors.

[0334] The electron transport layer 118 can be formed using a material and a process similar to those of the electron transport layer 113. The electron injection layer 119 can be formed using a material and a process similar to those of the electron injection layer 114.

[0335] Electrode 102 can be formed by layering a reflective conductive film and a translucent conductive film on top of each other. Electrode 102 can have a single-layer or a multi-layer structure.

[0336] By the steps described above, the light-emitting element, which comprises area 222B, area 222G and area 222R above electrode 101, electrode 103 and electrode 104 respectively, is formed above the substrate 200. <<Sechster Schritt> >

[0337] In the sixth step, the opaque layer 223, the optical element 224B, the optical element 224G and the optical element 224R are formed over the substrate 220 (see Fig. 8C).

[0338] An opaque layer 223, consisting of a resin film containing a black pigment, is formed in a desired area. Subsequently, optical elements 224B, 224G, and 224R are formed over substrate 220 and the opaque layer 223. Optical element 224B consists of a resin film containing a blue pigment, 224G of a resin film containing a green pigment, and 224R of a resin film containing a red pigment. <<Siebter Schritt> >

[0339] In the seventh step, the light-emitting element formed over the substrate 200 is attached to the opaque layer 223, the optical element 224B, the optical element 224G and the optical element 224R formed over the substrate 220 and sealed with a sealant (not shown).

[0340] The steps described above allow the light-emitting element 262a, which is in Fig. 6A is shown, to be trained.

[0341] The structure described in this embodiment can be used in a suitable combination with any of the structures described in the other embodiments. (Version 4)

[0342] In this embodiment, a display device of an embodiment of the present invention is described below by reference to Fig. 9A and Fig. 9B, Fig. 10A and Fig. 10B, Fig. 11, Fig. 12A and Fig. 12B, Fig. 13A and Fig. 13B, Fig. 14, Fig. 15A and Fig. 15B, Fig. 16 as well Fig. 17A and Fig. 17B described. <Strukturbeispiel 1 der Anzeigevorrichtung>

[0343] Fig. 9A is a top view showing a display device 600, and Fig. 9B is a cross-sectional view along the dashed-dotted line AB and the dashed-dotted line CD in Fig. 9A. The display device 600 comprises driver circuit sections (a signal line driver circuit section 601 and a scanning line driver circuit section 603) and a pixel section 602. It should be noted that the signal line driver circuit section 601, the scanning line driver circuit section 603, and the pixel section 602 have a function for controlling a light emission from a light-emitting element.

[0344] The display device 600 also comprises an element substrate 610, a sealing substrate 604, a sealing agent 605, a region 607 enclosed by the sealing agent 605, a connecting line 608 and an FPC 609.

[0345] It should be noted that the connecting line 608 is a line for transmitting signals input to the signal line driver circuit section 601 and the sample line driver circuit section 603, and for receiving a video signal, clock signal, start signal, reset signal, and the like from the FPC 609, which serves as an external input connector. Although only the FPC 609 is shown here, the FPC 609 may be mounted on a printed circuit board (PWB).

[0346] A CMOS circuit combining an n-channel transistor 623 and a p-channel transistor 624 is configured as the signal line driver circuit section 601. Various circuit types, such as a CMOS circuit, a PMOS circuit, or an NMOS circuit, can be used as the signal line driver circuit section 601 or as the sample line driver circuit section 603. Although a driver, in which a driver circuit section is configured, and a pixel are configured over the same surface of a substrate in the display device of this embodiment, the driver circuit section is not necessarily configured over the substrate and can be configured outside of the substrate.

[0347] The pixel section 602 comprises a switching transistor 611, a current control transistor 612, and a lower electrode 613, which is electrically connected to a drain of the current control transistor 612. It should be noted that a partition 614 is configured to cover end sections of the lower electrode 613. A positive photosensitive acrylic resin film, for example, can be used as the partition 614.

[0348] To achieve advantageous coverage, the partition 614 is designed to have a curved surface with a curvature at its upper or lower end section. For example, if a positive photosensitive acrylic is used as the material of the partition 614, preferably only the upper end section of the partition 614 has a curved surface with a curvature (where the radius of curvature is 0.2 µm to 3 µm). Either a negative photosensitive resin or a positive photosensitive resin can be used as the partition 614.

[0349] It should be noted that there is no particular restriction regarding the structure of each of the transistors (transistors 611, 612, 623, and 624). For example, a staggered transistor can be used. Furthermore, there is no particular restriction regarding the polarity of these transistors. Both n-channel and p-channel transistors can be used, or, for example, either n-channel or p-channel transistors can be used. In addition, there is no particular restriction regarding the crystallinity of a semiconductor film used for these transistors. For example, an amorphous semiconductor film or a crystalline semiconductor film can be used. Examples of semiconductor materials include Group 14 semiconductors (e.g., a semiconductor comprising silicon), compound semiconductors (including oxide semiconductors), organic semiconductors, and the like.For example, an oxide semiconductor having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more, is preferably used for the transistors so that the reverse current of the transistors can be reduced. Examples of the oxide semiconductor include an In-Ga oxide and an In-M-Zn oxide (M is aluminum (Al), gallium (Ga), yttrium (Y), zirconium (Zr), lanthanum (La), cerium (Ce), tin (Sn), hafnium (Hf), or neodymium (Nd)).

[0350] An EL layer 616 and an upper electrode 617 are formed above the lower electrode 613. Here, the lower electrode 613 serves as the anode, and the upper electrode 617 serves as the cathode.

[0351] Furthermore, the EL layer 616 is formed using various processes, such as evaporation via an evaporation mask, inkjet printing, or rotational coating. The EL layer 616 can also contain low-molecular-weight or high-molecular-weight compounds (including oligomers and dendrimers).

[0352] It should be noted that a light-emitting element 618 is formed with the lower electrode 613, the EL layer 616, and the upper electrode 617. The light-emitting element 618 preferably has any of the structures described in embodiments 1 to 3. In the case where the pixel section comprises a plurality of light-emitting elements, the pixel section can include either one of the light-emitting elements described in embodiments 1 to 3 or a light-emitting element with a different structure.

[0353] When the sealing substrate 604 and the element substrate 610 are joined together with the sealant 605, the light-emitting element 618 is provided in the area 607 enclosed by the element substrate 610, the sealing substrate 604, and the sealant 605. The area 607 is filled with a filler material. In some cases, the area 607 is filled with an inert gas (nitrogen, argon, or the like) or with a UV-curing or thermosetting resin that can be used for the sealant 605. For example, a polyvinyl chloride (PVC)-based resin, an acrylic-based resin, a polyimide-based resin, an epoxy-based resin, a silicone-based resin, a polyvinyl butyral (PVB)-based resin, or an ethylene vinyl acetate (EVA)-based resin can be used.Preferably, the sealing substrate is provided with a recessed part and a desiccant is arranged in the recessed part, whereby deterioration due to the influence of moisture can be prevented.

[0354] An optical element 621 is provided beneath the sealing substrate 604 to overlap the light-emitting element 618. An opaque layer 622 is provided beneath the sealing substrate 604. The structures of the optical element 621 and the opaque layer 622 can be the same as those of the optical element and the opaque layer, respectively, of embodiment 3.

[0355] An epoxy-based resin or a glass frit is preferably used for the sealant 605. Preferably, such a material allows as little moisture or oxygen to pass through as possible. A glass substrate, a quartz substrate, or a plastic substrate made of fiber-reinforced plastic (FRP), polyvinyl fluoride (PVF), polyester, acrylic, or the like can be used as the sealant substrate 604.

[0356] The display device, comprising any of the light-emitting elements and optical elements described in embodiments 1 to 3, can be obtained in the manner described above. <Strukturbeispiel 2 der Anzeigevorrichtung>

[0357] Next, another example of the display device will be given using... Fig. 10A and Fig. 10B as well Fig. 11 described. It should be noted that Fig. 10A and Fig. 10B as well Fig. 11 each represent a cross-sectional view of a display device of an embodiment of the present invention.

[0358] In Fig. Figure 10A 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 section 1042, a pixel section 1040, a driver circuit section 1041, lower electrodes 1024R, 1024G and 1024B of the light-emitting elements, a partition 1025, an EL layer 1028, an upper electrode 1026 of the light-emitting elements, a sealing layer 1029, a sealing substrate 1031, a sealing agent 1032 and the like.

[0359] In Fig. Figure 10A shows examples of optical elements consisting of color layers (a red color layer 1034R, a green color layer 1034G, and a blue color layer 1034B) on a transparent base material 1033. An opaque layer 1035 may also be provided. The transparent base material 1033, which is provided with the color layers and the opaque layer, is located on and attached to the substrate 1001. It should be noted that the color layers and the opaque layer are covered with a cover layer 1036. In the structure shown in Fig. 10A red light, green light and blue light pass through the color layers, and consequently an image can be displayed using pixels of three colors.

[0360] Fig. Figure 10B provides an example in which the color layers (the red color layer 1034R, the green color layer 1034G, and the blue color layer 1034B) are provided as examples of the optical elements between the gate insulating film 1003 and the first intermediate insulating film 1020. As with this structure, the color layers can be arranged between the substrate 1001 and the sealing substrate 1031.

[0361] Fig. Figure 11 presents an example in which the color layers (the red color layer 1034R, the green color layer 1034G, and the blue color layer 1034B) are provided as examples of the optical elements between the first interlayer insulating film 1020 and the second interlayer insulating film 1021. As with this structure, the color layers can be arranged between the substrate 1001 and the sealing substrate 1031.

[0362] The display device described above has a structure in which light is taken from the side of the substrate 1001 on which the transistors are formed (a bottom-emission structure); however, it can have a structure in which light is taken from the side of the sealing substrate 1031 (a top-emission structure). <Strukturbeispiel 3 der Anzeigevorrichtung>

[0363] Fig. 12A and Fig. Figures 12B are examples of cross-sectional views of a display device with a top-emission structure. It should be noted that Fig. 12A and Fig. 12B each are a cross-sectional view representing the display device of an embodiment of the present invention, and the driver circuit section 1041, the peripheral section 1042 and the like, which are shown in Fig. 10A and Fig. 10B as well Fig. Items shown in 11 are not shown in these.

[0364] In this case, a substrate that does not transmit light can be used as substrate 1001. The process up to the step of forming a connecting electrode that links the transistor and the anode of the light-emitting element is carried out in a similar manner to that of the display device with a bottom-emission structure. Subsequently, a third interlayer insulating film 1037 is formed such that it covers an electrode 1022. This insulating film may have a leveling function. The third interlayer insulating film 1037 can be formed using a material similar to that of the second interlayer insulating film or can be formed using various other materials.

[0365] The lower electrodes 1024R, 1024G and 1024B of the light-emitting elements each serve as anodes, but they can also serve as cathodes. In the case of a Fig. 12A and Fig. In the display device shown in Figure 12B, which has a top-emission structure, the lower electrodes 1024R, 1024G, and 1024B preferably also have a light-reflecting function. The upper electrode 1026 is provided above the EL layer 1028. Preferably, the upper electrode 1026 has both a light-reflecting and a light-transmitting function, and a microcavity structure can be used between the upper electrode 1026 and the lower electrodes 1024R, 1024G, and 1024B, in which case the intensity of the light with a specific wavelength is increased.

[0366] In the event of an Fig. The top-emission structure shown in Figure 12A can be sealed using the sealing substrate 1031, on which the color layers (the red color layer 1034R, the green color layer 1034G, and the blue color layer 1034B) are provided. The sealing substrate 1031 can be provided with the opaque layer 1035, which is positioned between pixels. It should be noted that a translucent substrate is advantageously used as the sealing substrate 1031.

[0367] Fig. Figure 12A provides an example of the structure provided with the light-emitting elements and the color layers for the light-emitting elements; however, the structure is not limited to this. For example, as shown in Fig. Figure 12B shows a structure that includes the red color layer 1034R and the blue color layer 1034B, but no green color layer, to achieve a full-color display using the three colors red, green, and blue. The structure shown in Fig. The structure shown in Figure 12A, in which the light-emitting elements are provided with the color layers, is effective at suppressing the reflection of external light. In contrast, the structure shown in Fig. The structure shown in Figure 12B, in which the light-emitting elements are provided with the red color layer and the blue color layer, but without the green color layer, effectively reduces power consumption due to a low energy loss of the light emitted by the green light-emitting element. <Strukturbeispiel 4 der Anzeigevorrichtung>

[0368] Although a display device comprising subpixels of three colors (red, green and blue) has been described above, the number of colors of subpixels can be four (red, green, blue and yellow, or red, green, blue and white). Fig. 13A and Fig. 13B, Fig. 14 as well Fig. 15A and Fig. 15B represent structures of display devices, each comprising the lower electrodes 1024R, 1024G, 1024B and 1024Y. Fig. 13A and Fig. 13B as well Fig. 14 each represent a display device with a structure in which light is extracted from the side of the substrate 1001 on which transistors are formed (bottom emission structure), and Fig. 15A and Fig. 15B each represent a display device with a structure in which light is extracted from the side of the sealing substrate 1031 (top emission structure).

[0369] Fig. 13A represents an example of a display device in which optical elements (the color layer 1034R, the color layer 1034G, the color layer 1034B and a color layer 1034Y) are provided on the transparent base material 1033. Fig. 13B represents an example of a display device in which optical elements (the color layer 1034R, the color layer 1034G, the color layer 1034B and the color layer 1034Y) are provided between the gate insulating film 1003 and the first intermediate layer insulating film 1020. Fig. Figure 14 provides an example of a display device in which optical elements (the color layer 1034R, the color layer 1034G, the color layer 1034B and the color layer 1034Y) are provided between the first interlayer insulating film 1020 and the second interlayer insulating film 1021.

[0370] The 1034R color layer transmits red light, the 1034G color layer transmits green light, and the 1034B color layer transmits blue light. The 1034Y color layer transmits yellow light or light of a variety of colors selected from blue, green, yellow, and red. Since the 1034Y color layer transmits light of a variety of colors selected from blue, green, yellow, and red, the light passing through the 1034Y color layer can be white light. Because the light-emitting element emitting yellow or white light has high emission efficiency, the display device incorporating the 1034Y color layer can have low power consumption.

[0371] The top emission indicator devices, which are in Fig. 15A and Fig. Figure 15B shows a light-emitting element comprising the lower electrode 1024Y, preferably having a microcavity structure between the upper electrode 1026 and the lower electrodes 1024R, 1024G, 1024B and 1024Y, as in the display device shown in Fig. 12A is shown. The display device, which is in Fig. As shown in 15A, sealing can be carried out with the sealing substrate 1031, on which the color layers (the red color layer 1034R, the green color layer 1034G, the blue color layer 1034B and the yellow color layer 1034Y) are provided.

[0372] Light emitted through the microcavity and the yellow 1034Y color layer exhibits an emission spectrum in the yellow range. Since yellow is a color with a high luminance factor, a light-emitting element that emits yellow light has a high emission efficiency. Consequently, the display device can be used in Fig. 15A exhibit reduced power consumption.

[0373] Fig. Figure 15A provides an example of the structure provided with the light-emitting elements and the color layers for the light-emitting elements; however, the structure is not limited to this. For example, as shown in Fig. Figure 15B shows a structure comprising the red color layer 1034R, the green color layer 1034G, and the blue color layer 1034B, but no yellow color layer, to achieve a full-color display using the four colors red, green, blue, and yellow, or red, green, blue, and white. The structure in which the light-emitting elements are provided with the color layers is, as shown in Fig. Figure 15A is shown to be effective in suppressing the reflection of external light. In contrast, the structure in which the light-emitting elements are provided with the red, green, and blue color layers, but without the yellow color layer, is shown in Figure 15A. Fig. 15B shows that, due to a low energy loss of the light emitted by the yellow or white light emitting element, it is effective in reducing power consumption. <Strukturbeispiel 5 der Anzeigevorrichtung>

[0374] Next, a display device of a further embodiment of the present invention will be described using the following examples: Fig. 16 described. Fig. Figure 16 is a cross-sectional view along the dashed line AB and the dashed line CD in Fig. 9A. It should be noted that in Fig. 16 sections with functions similar to those of sections in Fig. 9B same, with the same reference symbols as in Fig. are marked 9B, and a detailed description of the sections is omitted.

[0375] The display device 600 in Fig. 16 comprises a sealing layer 607a, a sealing layer 607b, and a sealing layer 607c within a region 607 enclosed by the element substrate 610, the sealing substrate 604, and the sealant 605. For one or more of the sealing layers 607a, 607b, and 607c, a resin such as a polyvinyl chloride (PVC)-based resin, an acrylic-based resin, a polyimide-based resin, an epoxy-based resin, a silicone-based resin, a polyvinyl butyral (PVB)-based resin, or an ethylene vinyl acetate (EVA)-based resin may be used. Alternatively, an inorganic material such as silicon dioxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, or aluminum nitride may be used. The formation of the sealing layers 607a, 607b and 607c can prevent the light-emitting element 618 from becoming obstructed due to impurities, such as e.g.Water deteriorates, which is preferable. In the case where sealing layers 607a, 607b and 607c are formed, the sealant 605 is not necessarily provided.

[0376] Alternatively, any one or two of the sealing layers 607a, 607b, and 607c may be provided, or four or more sealing layers may be formed. If the sealing layer has a multilayer structure, water and other contaminants from the outside of the display device 600 can be effectively prevented from penetrating the light-emitting element 618 located inside the display device. In the case where the sealing layer has a multilayer structure, a resin and an inorganic material are preferably arranged one on top of the other. <Strukturbeispiel 6 der Anzeigevorrichtung>

[0377] Although the display devices of structural examples 1 to 4 each have a structure comprising optical elements in this embodiment, an embodiment of the present invention does not necessarily include an optical element.

[0378] Fig. 17A and Fig. 17B each represent a display device with a structure in which light is extracted from the side of the sealing substrate 1031 (a top emission display device). Fig. 17A represents an example of a display device comprising a light-emitting layer 1028R, a light-emitting layer 1028G and a light-emitting layer 1028B. Fig. 17B represents an example of a display device comprising a light-emitting layer 1028R, a light-emitting layer 1028G, a light-emitting layer 1028B and a light-emitting layer 1028Y.

[0379] The light-emitting layer 1028R has a function for emitting red light, the light-emitting layer 1028G has a function for emitting green light, and the light-emitting layer 1028B has a function for emitting blue light. The light-emitting layer 1028Y has a function for emitting yellow light or a function for emitting light of a variety of colors selected from blue, green, and red. The light-emitting layer 1028Y can emit white light. Because the light-emitting element that emits yellow or white light has a high light emission efficiency, the display device incorporating the light-emitting layer 1028Y can have low power consumption.

[0380] Each of the display devices in Fig. 17A and Fig. 17B does not necessarily include color layers that serve as optical elements, since EL layers, which exhibit light of different colors, are contained in subpixels.

[0381] For the sealing layer 1029, a resin such as a polyvinyl chloride (PVC)-based resin, an acrylic-based resin, a polyimide-based resin, an epoxy-based resin, a silicone-based resin, a polyvinyl butyral (PVB)-based resin, or an ethylene vinyl acetate (EVA)-based resin can be used. Alternatively, an inorganic material such as silicon dioxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, or aluminum nitride can be used. The formation of the sealing layer 1029 can prevent the light-emitting element from deteriorating due to impurities such as water, which is preferable.

[0382] Alternatively, the sealing layer 1029 can have a single-layer or a two-layer structure, or four or more sealing layers can be formed as the sealing layer 1029. If the sealing layer has a multi-layer structure, contaminants, such as water, can be effectively prevented from penetrating from the outside of the display device into the interior of the display device. In the case where the sealing layer has a multi-layer structure, a resin and an inorganic material are preferably arranged one on top of the other.

[0383] It should be noted that the sealing substrate 1031 has a function to protect the light-emitting element. Therefore, a flexible substrate or a flexible film can be used for the sealing substrate 1031.

[0384] The structures described in this embodiment can be appropriately combined with any of the other structures of this embodiment and of the other embodiments. (Version 5)

[0385] In this embodiment, a display device comprising a light-emitting element of an embodiment of the present invention is used by means of Fig. 18A and Fig. 18B, Fig. 19A and Fig. 19B as well Fig. 20A and Fig. 20B described.

[0386] Fig. 18A is a block diagram representing the display device of an embodiment of the present invention, and Fig. Figure 18B is a circuit diagram that represents a pixel circuit of the display device of an embodiment of the present invention. <Beschreibung der Anzeigevorrichtung>

[0387] The display device, which is in Fig. The circuit shown in Figure 18A comprises a section containing pixels of display elements (hereinafter referred to as the pixel section 802), a circuit section provided outside the pixel section 802 and comprising circuits for driving the pixels (hereinafter referred to as the driver circuit section 804), circuits having a function for protecting elements (hereinafter referred to as the protection circuits 806), and a terminal section 807. It should be noted that the protection circuits 806 are not necessarily provided.

[0388] Preferably, part or all of the driver circuit section 804 is formed on a substrate on which the pixel section 802 is formed, in which case the number of components and the number of connections can be reduced. If part or all of the driver circuit section 804 is not formed on the substrate on which the pixel section 802 is formed, the part or all of the driver circuit section 804 can be mounted by COG or tape-automated bonding (TAB).

[0389] The pixel section 802 comprises a variety of circuits for driving the display elements, which are arranged in X rows (X is a natural number greater than or equal to 2) and Y columns (Y is a natural number greater than or equal to 2) (hereafter such circuits are referred to as pixel circuits 801). The driver circuit section 804 comprises driver circuits, such as a circuit for outputting a signal (sampling signal) to select a pixel (hereafter referred to as the sampling line driver circuit 804a), and a circuit for supplying a signal (data signal) to drive a display element in a pixel (hereafter referred to as the signal line driver circuit 804b).

[0390] The 804a sample line driver circuit comprises a shift register or the like. Via terminal 807, the 804a sample line driver circuit receives a signal to drive the shift register and outputs a signal. For example, the 804a sample line driver circuit receives a start pulse signal, a clock signal, or the like and outputs a pulse signal. The 804a sample line driver circuit has a function for controlling the potentials of lines to which sample signals are supplied (hereafter referred to as sample lines GL_1 to GL_X). It should be noted that multiple 804a sample line driver circuits can be provided to control sample lines GL_1 to GL_X separately. Alternatively, the 804a sample line driver circuit has a function for supplying an initialization signal.Without being limited to this, the 804a sampling line driver circuit can supply a different signal.

[0391] The signal line driver circuit 804b includes a shift register or the like. Via connection section 807, the signal line driver circuit 804b receives a signal (video signal) from which a data signal is derived, and a signal to drive the shift register. The signal line driver circuit 804b has a function for generating a data signal, which is written to the pixel circuit 801, based on the video signal. The signal line driver circuit 804b also has a function for controlling the output of a data signal in response to a pulse signal generated by input of a start pulse, clock signal, or the like. The signal line driver circuit 804b further has a function for controlling the potentials of lines to which data signals are supplied (hereafter referred to as data lines DL_1 to DL_Y).Alternatively, the 804b signal line driver circuit has a function for supplying an initialization signal. While not limited to this, the 804b signal line driver circuit can supply a different signal.

[0392] The 804b signal line driver circuit, for example, comprises a variety of analog switches or the like. The 804b signal line driver circuit can output signals obtained by time-dividing the video signal as data signals by sequentially turning on the variety of analog switches. The 804b signal line driver circuit may also include a shift register or the like.

[0393] A pulse signal and a data signal are input into each of the multiple pixel circuits 801 via one of the multiple sample lines GL, to which sample signals are supplied, and via one of the multiple data lines DL, to which data signals are supplied. The writing and holding of the data signal in each of the multiple pixel circuits 801 are controlled by the sample line driver circuit 804a. For example, in the pixel circuit 801 in the m-th row and n-th column (m is a natural number less than or equal to X, and n is a natural number less than or equal to Y), a pulse signal from the sample line driver circuit 804a is input via the sample line GL_m, and a data signal is input from the signal line driver circuit 804b via the data line DL_n according to the potential of the sample line GL_m.

[0394] The in Fig. The protection circuit 806 shown in Figure 18A is, for example, connected to the sampling line GL between the sampling line driver circuit 804a and the pixel circuit 801. Alternatively, the protection circuit 806 is connected to the data line DL between the signal line driver circuit 804b and the pixel circuit 801. Alternatively, the protection circuit 806 can be connected to a line between the sampling line driver circuit 804a and the terminal section 807. Alternatively, the protection circuit 806 can be connected to a line between the signal line driver circuit 804b and the terminal section 807. It should be noted that the terminal section 807 is a section with terminals through which power, control signals, and video signals from external circuits are input into the display device.

[0395] The 806 protection circuit is a circuit that electrically connects a conductor connected to the protection circuit to another conductor when a potential outside a certain range is applied to the conductor connected to the protection circuit.

[0396] As in Fig. As shown in Figure 18A, the protection circuits 806 are provided for the pixel section 802 and the driver circuit section 804, thus improving the resistance of the display device to overcurrent caused by electrostatic discharge (ESD) or the like. It should be noted that the configuration of the protection circuits 806 is not limited to this; for example, a configuration in which the protection circuits 806 are connected to the sample line driver circuit 804a, or a configuration in which the protection circuits 806 are connected to the signal line driver circuit 804b, may be used. Alternatively, the protection circuits 806 may be configured to be connected to the terminal section 807.

[0397] In Fig. Figure 18A shows an example in which the driver circuit section 804 comprises the sampling line driver circuit 804a and the signal line driver circuit 804b; however, the structure is not limited thereto. For example, only the sampling line driver circuit 804a can be formed, and a separately prepared substrate on which a signal line driver circuit is formed (e.g., a driver circuit substrate formed from a single-crystal semiconductor film or a polycrystalline semiconductor film) can be mounted. <Strukturbeispiel der Pixelschaltung>

[0398] Each of the multitude of 801 pixel circuits in Fig. 18A can, for example, be used in Fig. exhibit the structure shown in 18B.

[0399] The in Fig. The pixel circuit 801 shown in Figure 18B comprises transistors 852 and 854, a capacitor 862 and a light-emitting element 872.

[0400] Either a source electrode or a drain electrode of transistor 852 is electrically connected to a line carrying a data signal (a data line DL_n). A gate electrode of transistor 852 is electrically connected to a line carrying a gate signal (a sampling line GL_m).

[0401] The 852 transistor has a function to control whether a data signal is written.

[0402] One of a pair of electrodes of capacitor 862 is electrically connected to a line to which a potential is supplied (hereinafter referred to as the potential supply line VL_a), and the other is electrically connected to the other of the source electrode and the drain electrode of transistor 852.

[0403] The capacitor 862 serves as a storage capacitor for storing the written data.

[0404] Either a source electrode or a drain electrode of transistor 854 is electrically connected to the potential supply line VL_a. Furthermore, a gate electrode of transistor 854 is electrically connected to the other source electrode and the drain electrode of transistor 852.

[0405] Either one anode or one cathode of the light-emitting element 872 is electrically connected to a potential supply line VL_b, and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 854.

[0406] Any of the light-emitting elements described in embodiments 1 to 3 can be used as the light-emitting element 872.

[0407] It should be noted that a high power supply potential VDD is supplied either to the potential supply line VL_a or the potential supply line VL_b, and a low power supply potential VSS is supplied to the other line.

[0408] For example, in the display device, which includes the 801 pixel circuits, in Fig. 18B the pixel circuits 801 through the sampling line driver circuit 804a in Fig. 18A is selected sequentially, row by row, which turns on transistors 852 and writes a data signal.

[0409] When transistors 852 are switched off, the pixel circuits 801, into which the data has been written, are put into a hold state. The magnitude of the current flowing between the source and drain electrodes of transistor 854 is further controlled according to the potential of the written data signal. The light-emitting element 872 emits light with a luminance corresponding to the magnitude of the current flowing. This process is carried out sequentially, line by line; in this way, an image is displayed.

[0410] Alternatively, the pixel circuit can have a function to compensate for fluctuations in the threshold voltages or the like of a transistor. Fig. 19A and Fig. 19B as well Fig. 20A and Fig. 20B provide examples of pixel circuitry.

[0411] The pixel circuitry that is in Fig. Figure 19A comprises six transistors (transistors 303_1 to 303_6), a capacitor 304, and a light-emitting element 305. The pixel circuit shown in Fig. The component shown in Figure 19A is electrically connected to lines 301_1 to 301_5 and lines 302_1 and 302_2. It should be noted that p-channel transistors, for example, can be used as transistors 303_1 to 303_6.

[0412] The pixel circuitry that is in Fig. As shown in 19B, it has a configuration in which the pixel circuitry shown in Fig. As shown in 19A, a 303_7 transistor is added. The pixel circuit shown in Fig. The component shown in Figure 19B is electrically connected to lines 301_6 and 301_7. Lines 301_5 and 301_6 can be electrically connected to each other. It should be noted that, for example, a p-channel transistor can be used as transistor 303_7.

[0413] The pixel circuitry that is in Fig. The circuit shown in 20A comprises six transistors (transistors 308_1 to 308_6), capacitor 304, and light-emitting element 305. The pixel circuit shown in Fig. The 20A shown is electrically connected to lines 306_1 to 306_3 and lines 307_1 to 307_3. Lines 306_1 and 306_3 can be electrically connected to each other. It should be noted that, for example, p-channel transistors can be used as transistors 308_1 to 308_6.

[0414] The pixel circuitry that is in Fig. The circuit shown in 20B comprises two transistors (transistors 309_1 and 309_2), two capacitors (capacitors 304_1 and 304_2), and the light-emitting element 305. The pixel circuit shown in Fig. The component shown in Figure 20B is electrically connected to lines 311_1 to 311_3 and lines 312_1 and 312_2. With the configuration of the pixel circuit shown in Fig. As shown in Figure 20B, the pixel circuit can be driven by a voltage input current driving method (also known as CVCC). It should be noted that, for example, p-channel transistors can be used for transistors 309_1 and 309_2.

[0415] A light-emitting element of an embodiment of the present invention can be used for an active matrix method in which an active element is contained in a pixel of a display device, or for a passive matrix method in which no active element is contained in a pixel of a display device.

[0416] In active matrix transistors, not only transistors but also various other active elements (nonlinear elements) can be used as the active element (nonlinear element). For example, a metal-insulator-metal (MIM), a thin-film diode (TFD), or similar devices can also be used. Since these elements can be fabricated with fewer steps, manufacturing costs can be reduced or the yield improved. Alternatively, because these elements are small, the aperture ratio can be improved, thus reducing power consumption and achieving higher luminance.

[0417] In addition to the active matrix method, the passive matrix method can also be used, which does not employ an active element (no nonlinear element). Since no active element (no nonlinear element) is used, the number of manufacturing steps is reduced, thus lowering production costs or improving yield. Alternatively, because no active element (no nonlinear element) is used, the aperture ratio can be improved, allowing, for example, reduced power consumption or higher luminance to be achieved.

[0418] The structure described in this embodiment can be used in a suitable combination with any of the structures described in the other embodiments. (Version 6)

[0419] In this embodiment, a display device comprising a light-emitting element of an embodiment of the present invention and an electronic device in which the display device is provided with an input device are connected by means of Fig. 21A and Fig. 21B, Fig. 22A to Fig. 22C, Fig. 23A and Fig. 23B, Fig. 24A and Fig. 24B as well Fig. 25 described. <Beschreibung 1 des Touchscreens>

[0420] In this embodiment, a touchscreen 2000, comprising a display device and an input device, is described as an example of an electronic device. An example is also described in which a touch sensor is included as the input device.

[0421] Fig. 21A and Fig. Figures 21B are perspective views of the Touchscreen 2000. It should be noted that... Fig. 21A and Fig. For the sake of simplicity, section 21B only shows the main components of the Touchscreen 2000.

[0422] The Touchscreen 2000 includes a display device 2501 and a touch sensor 2595 (see Fig. 21B). The Touchscreen 2000 further comprises a substrate 2510, a substrate 2570, and a substrate 2590. The substrate 2510, the substrate 2570, and the substrate 2590 each exhibit flexibility. It should be noted that one or all of the substrates 2510, 2570, and 2590 may be inelastic.

[0423] The display device 2501 comprises a plurality of pixels above the substrate 2510 and a plurality of lines 2511 through which signals are supplied to the pixels. The plurality of lines 2511 extends to a peripheral section of the substrate 2510, and portions of the plurality of lines 2511 form a terminal 2519. The terminal 2519 is electrically connected to an FPC 2509(1). The plurality of lines 2511 can supply signals to the plurality of pixels from a signal line driver circuit 2503s(1).

[0424] The substrate 2590 comprises the touch sensor 2595 and a plurality of wires 2598 that are electrically connected to the touch sensor 2595. The plurality of wires 2598 extends to a peripheral section of the substrate 2590, and portions of the plurality of wires 2598 form a terminal. The terminal is electrically connected to an FPC 2509(2). It should be noted that in Fig. 21B Electrodes, wires and the like of the touch sensor 2595, which is provided on the back of the substrate 2590 (the side facing the substrate 2510), are shown by solid lines for clarity.

[0425] A capacitive touch sensor can be used as the 2595 touch sensor. Examples of capacitive touch sensors include surface capacitive touch sensors and projected capacitive touch sensors.

[0426] Examples of projected capacitive touch sensors include self-capacitive and mutual capacitive touch sensors, which differ primarily in their control method. A mutual capacitive touch sensor is preferred because it allows for the simultaneous detection of multiple points.

[0427] It should be noted that the touch sensor 2595, which is in Fig. Figure 21B shows an example where a projected capacitive touch sensor is used.

[0428] It should be noted that various sensors can be used as touch sensors 2595, which can detect the proximity or touch of a detection object, such as a finger.

[0429] The projected capacitive touch sensor 2595 comprises electrodes 2591 and electrodes 2592. The electrodes 2591 are electrically connected to one of the plurality of lines 2598, and the electrodes 2592 are electrically connected to one of the other lines 2598.

[0430] The electrodes 2592 each have a shape consisting of a plurality of quadrilaterals arranged in one direction, with one corner of one quadrilateral connected to a corner of another quadrilateral, as shown in Fig. 21A and Fig. 21B is shown.

[0431] The electrodes 2591 each have a square shape and are arranged in a direction that intersects the direction in which the electrodes 2592 extend.

[0432] A conductor 2594 electrically connects two electrodes 2591, between which the electrode 2592 is positioned. The interface between the electrode 2592 and the conductor 2594 is preferably as small as possible. Such a structure allows for a reduction in the area where the electrodes are not present, thereby reducing fluctuations in light transmittance. This, in turn, reduces fluctuations in the luminance of light passing through the touch sensor 2595.

[0433] It should be noted that the shapes of the electrodes 2591 and the electrodes 2592 are not limited and can have any number of different shapes. For example, a structure can be used in which the plurality of electrodes 2591 are arranged such that the gaps between the electrodes 2591 are minimized, and the electrodes 2592 are arranged separately from the electrodes 2591 with an insulating layer between them to provide areas that do not overlap the electrodes 2591. In this case, it is preferred that a dummy electrode be provided between two adjacent electrodes 2592, which is electrically isolated from these electrodes, since this reduces the area of ​​regions exhibiting different light transmittances. <Beschreibung der Anzeigevorrichtung>

[0434] Next, the display device 2501 will be described in detail using the following examples: Fig. 22A described. Fig. 22A corresponds to a cross-sectional view along the dashed line X1-X2 in Fig. 21B.

[0435] The display device 2501 comprises a plurality of pixels arranged in a matrix. Each pixel includes a display element and a pixel circuit for controlling the display element.

[0436] The following description provides an example where a light-emitting element that emits white light is used as the display element; however, the display element is not limited to such an element. For example, it can contain light-emitting elements that emit light of different colors, so that light of different colors can be emitted from neighboring pixels.

[0437] For substrate 2510 and substrate 2570, for example, a flexible material with a water vapor permeability of less than or equal to 1 × 10 can be used. -5 g·m -2 ·Day -1 preferably less than or equal to 1 × 10 -6 g·m -2 ·Day -1 , can be used advantageously. Alternatively, materials whose coefficients of thermal expansion are essentially the same are preferably used for substrate 2510 and substrate 2570. For example, the coefficients of linear expansion of the materials are preferably less than or equal to 1 × 10 -3 / K, more strongly preferred, less than or equal to 5 × 10 -5 / K, even more strongly preferred to be lower than or equal to 1 × 10 -5 / K.

[0438] It should be noted that substrate 2510 is a layered arrangement consisting of an insulating layer 2510a for preventing the diffusion of impurities into the light-emitting element, a flexible substrate 2510b, and an adhesive layer 2510c for attaching the insulating layer 2510a to the flexible substrate 2510b. Substrate 2570 is a layered arrangement consisting of an insulating layer 2570a for preventing the diffusion of impurities into the light-emitting element, a flexible substrate 2570b, and an adhesive layer 2570c for attaching the insulating layer 2570a to the flexible substrate 2570b.

[0439] For adhesive layer 2510c and adhesive layer 2570c, materials such as polyester, polyolefin, polyamide (e.g., nylon, aramid), polyimide, polycarbonate, or an acrylic resin, polyurethane, or an epoxy resin can be used. Alternatively, a material containing a resin with a siloxane bond, such as silicone, can be used.

[0440] A sealing layer 2560 is provided between the substrate 2510 and the substrate 2570. The sealing layer 2560 preferably has a higher refractive index than air. In the case where light, as in Fig. 22A shown, taken from the side of the sealing layer 2560, the sealing layer 2560 can also serve as an optical adhesive layer.

[0441] A sealant can be formed in the peripheral section of the sealing layer 2560. Using the sealant, a light-emitting element 2550R can be provided in a region enclosed by the substrate 2510, the substrate 2570, the sealing layer 2560, and the sealant. It should be noted that an inert gas (such as nitrogen and argon) can be used instead of the sealing layer 2560. A desiccant can be provided in the inert gas to adsorb moisture or the like. A resin, such as an acrylic resin or an epoxy resin, can be used. An epoxy-based resin or a glass frit is preferably used for the sealant. The material used for the sealant is preferably one that is impermeable to both moisture and oxygen.

[0442] The display device 2501 comprises a pixel 2502R. The pixel 2502R comprises a light-emitting module 2580R.

[0443] The pixel 2502R comprises the light-emitting element 2550R and a transistor 2502t, which can supply electrical energy to the light-emitting element 2550R. It should be noted that the transistor 2502t serves as part of the pixel circuit. The light-emitting module 2580R comprises the light-emitting element 2550R and a color layer 2567R.

[0444] The light-emitting element 2550R comprises a lower electrode, an upper electrode, and an EL layer between the lower and upper electrodes. Any of the light-emitting elements described in embodiments 1 to 3 can be used as the light-emitting element 2550R.

[0445] A microcavity structure can be used between the lower electrode and the upper electrode, so that the intensity of light of a specific wavelength can be increased.

[0446] In the case where the sealing layer 2560 is provided on the light extraction side, the sealing layer 2560 is in contact with the light emitting element 2550R and the color layer 2567R.

[0447] The color layer 2567R is positioned in an area that overlaps the light-emitting element 2550R. Consequently, some of the light emitted by the light-emitting element 2550R passes through the color layer 2567R and is emitted to the outside of the light-emitting module 2580R, as indicated by an arrow in the drawing.

[0448] The display device 2501 comprises an opaque layer 2567BM on the light extraction side. The opaque layer 2567BM is arranged such that it encloses the color layer 2567R.

[0449] The 2567R color layer is a color layer with a function of transmitting light within a specific wavelength range. For example, a color filter can be used to transmit light in the red wavelength range, a color filter to transmit light in the green wavelength range, a color filter to transmit light in the blue wavelength range, a color filter to transmit light in the yellow wavelength range, or the like. Each color filter can be formed from any number of different materials using a printing process, an inkjet process, an etching process using photolithography, or the like.

[0450] An insulating layer 2521 is provided in the display device 2501. The insulating layer 2521 covers the transistor 2502t. It should be noted that the insulating layer 2521 has a function of covering an unevenness caused by the pixel circuit. The insulating layer 2521 may also have a function of suppressing the diffusion of impurities. This can prevent the reliability of the transistor 2502t or the like from being reduced by the diffusion of impurities.

[0451] The light-emitting element 2550R is formed above the insulating layer 2521. A partition 2528 is provided such that it overlaps the end section of the lower electrode of the light-emitting element 2550R. It should be noted that a spacer for controlling the distance between the substrate 2510 and the substrate 2570 can be formed above the partition 2528.

[0452] A sampling line driver circuit 2503g(1) comprises a transistor 2503t and a capacitor 2503c. It should be noted that the driver circuit can be formed in the same process and on the same substrate as the pixel circuits.

[0453] Above substrate 2510 are lines 2511, through which signals can be supplied. Connection 2519 is provided above lines 2511. The FPC 2509(1) is electrically connected to connection 2519. The FPC 2509(1) has a function for supplying a video signal, a clock signal, a start signal, a reset signal, or the like. It should be noted that the FPC 2509(1) can be provided with a PCB.

[0454] The 2501 display device can use transistors with different structures. Fig. Figure 22A represents an example in which bottom-gate transistors are used; however, the present invention is not limited to this example, and top-gate transistors can be used in the display device 2501, as shown in Figure 22A. Fig. 22B shown.

[0455] Furthermore, there is no particular restriction regarding the polarity of transistors 2502t and 2503t. Both n-channel and p-channel transistors can be used for these transistors, or, for example, either n-channel or p-channel transistors can be used. In addition, there is no particular restriction regarding the crystallinity of a semiconductor film used for transistors 2502t and 2503t. For example, an amorphous semiconductor film or a crystalline semiconductor film can be used. Examples of semiconductor materials include group 14 semiconductors (e.g., a semiconductor comprising silicon), compound semiconductors (including oxide semiconductors), organic semiconductors, and the like.Preferably, an oxide semiconductor having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more, is used for one or both of the transistors 2502t and 2503t, so that the reverse current of the transistors can be reduced. Examples of the oxide semiconductors include an In-Ga oxide, an In-M-Zn oxide (M representing Al, Ga, Y, Zr, La, Ce, Sn, Hf or Nd) and the like. <Beschreibung des Berührungssensors>

[0456] Next, the 2595 touch sensor will be described in detail using the following examples: Fig. 22C described. Fig. 22C corresponds to a cross-sectional view along the dashed line X3-X4 in Fig. 21B.

[0457] The touch sensor 2595 comprises the electrodes 2591 and the electrodes 2592, which are arranged in an offset arrangement on the substrate 2590, an insulating layer 2593 that covers the electrodes 2591 and the electrodes 2592, and the conductor 2594 that electrically connects the adjacent electrodes 2591.

[0458] Electrodes 2591 and 2592 are formed using a translucent conductive material. A conductive oxide, such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium has been added, can be used as the translucent conductive material. It should be noted that a graphene-containing film can also be used. The graphene-containing film can be formed, for example, by reducing a graphene oxide-containing film. A heat-based reduction process or similar method can be employed.

[0459] The electrodes 2591 and the electrodes 2592 can be formed by, for example, depositing a translucent conductive material onto the substrate 2590 by a sputtering process and then removing an unnecessary part by any of the various structuring techniques, such as photolithography.

[0460] Examples of a material for the insulating layer 2593 are a resin, such as an acrylic resin or an epoxy resin, a resin with a siloxane bond, and an inorganic insulating material, such as silicon dioxide, silicon oxynitride, or aluminum oxide.

[0461] Openings reaching the electrodes 2591 are formed in the insulating layer 2593, and the conductor 2594 electrically connects the adjacent electrodes 2591. A translucent conductive material can be advantageously used as the conductor 2594, as this increases the aperture ratio of the touchscreen. Furthermore, a material with a higher conductivity than electrodes 2591 and 2592 can be advantageously used for the conductor 2594, as this reduces the electrical resistance.

[0462] An electrode 2592 extends in one direction, and a plurality of electrodes 2592 are provided in strip form. The conductor 2594 crosses the electrode 2592.

[0463] Adjacent electrodes 2591 are provided, with an electrode 2592 positioned between them. The conductor 2594 electrically connects the adjacent electrodes 2591.

[0464] It should be noted that the plurality of electrodes 2591 is not necessarily arranged in the direction orthogonal to an electrode 2592 and may be arranged such that it crosses an electrode 2592 at an angle of more than 0° and less than 90°.

[0465] The conductor 2598 is electrically connected to one of the electrodes 2591 and 2592. A portion of the conductor 2598 serves as a terminal. The conductor 2598 can be made of a metal such as aluminum, gold, platinum, silver, nickel, titanium, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium, or an alloy containing any of these metals.

[0466] It should be noted that an insulating layer covering the insulating layer 2593 and the conductor 2594 may be provided to protect the touch sensor 2595.

[0467] A connection layer 2599 electrically connects the line 2598 to the FPC 2509(2).

[0468] Any different anisotropic conductive film (ACF), anisotropic conductive paste (ACP), or the like can be used as the junction layer 2599. <Beschreibung 2 des Touchscreens>

[0469] Next, the Touchscreen 2000 will be described in detail using the following examples: Fig. 23A described. Fig. 23A corresponds to a cross-sectional view along the dashed-dotted line X5-X6 in Fig. 21A.

[0470] The Touchscreen 2000, which is in Fig. The display device 2501, shown in 23A, is based on Fig. 22A has been described, and the touch sensor 2595, which is based on Fig. 22C has been described, attached to each other.

[0471] The 2000 touch sensor, which is in Fig. 23A includes, in addition to the components shown based on Fig. 22A and Fig. 22C have been described, an adhesive layer 2597 and an anti-reflective layer 2567p.

[0472] The adhesive layer 2597 is provided in contact with the conductor 2594. It should be noted that the adhesive layer 2597 bonds the substrate 2590 to the substrate 2570 such that the touch sensor 2595 overlaps the display device 2501. The adhesive layer 2597 preferably has a light-transmitting property. A thermosetting resin or a UV-curing resin can be used for the adhesive layer 2597. For example, an acrylic resin, a urethane-based resin, an epoxy-based resin, or a siloxane-based resin can be used.

[0473] The 2567p antireflection layer is positioned in an area that overlaps pixels. A circularly polarizing plate, for example, can be used as the 2567p antireflection layer.

[0474] Next, a touchscreen with a structure that differs from the one in Fig. 23A, which is shown, differs based on Fig. 23B described.

[0475] Fig. 23B is a cross-sectional view of a Touchscreen 2001. The Touchscreen 2001, which is in Fig. The one shown in 23B differs from the touchscreen 2000, which is shown in Fig. Figure 23A shows the relative position of the touch sensor 2595 to the display device 2501. Different parts are described in detail below, and for the other similar structures, reference is made to the preceding description of the touchscreen 2000.

[0476] The color layer 2567R is positioned in an area that overlaps the light-emitting element 2550R. The light-emitting element 2550R, which is in Fig. As shown in figure 23B, light is emitted towards the side where transistor 2502t is located. Therefore, some of the light emitted by light-emitting element 2550R passes through the color layer 2567R and is emitted towards the outside of light-emitting module 2580R, as indicated by an arrow in figure 23B. Fig. 23B shows.

[0477] The touch sensor 2595 is provided on the side of the substrate 2510 of the display device 2501.

[0478] The adhesive layer 2597 is provided between the substrate 2510 and the substrate 2590 and attaches the touch sensor 2595 to the display device 2501.

[0479] As in Fig. 23A or Fig. As shown in Figure 23B, light can be emitted from the light-emitting element via one or both of the substrates 2510 and 2570. <Beschreibung eines Verfahrens zum Ansteuern des Touchscreens>

[0480] Next, an example of a method for controlling a touchscreen will be given using... Fig. 24A and Fig. 24B described.

[0481] Fig. Figure 24A is a block diagram illustrating the structure of a mutual capacitive touch sensor. Fig. 24A represents a pulse voltage output circuit 2601 and a current sensing circuit 2602. It should be noted that in Fig. 24A six lines X1 to X6 represent the electrodes 2621 to which a pulse voltage is applied, and six lines Y1 to Y6 represent the electrodes 2622, which detect changes in current. Fig. 24A also represents capacitors 2603, each formed in a region where electrodes 2621 and 2622 overlap. It should be noted that a functional exchange between electrodes 2621 and 2622 is possible.

[0482] The pulse voltage output circuit 2601 is a circuit for sequentially applying a pulse voltage to lines X1 to X6. Applying a pulse voltage to lines X1 to X6 generates an electric field between electrodes 2621 and 2622 of capacitor 2603. If the electric field between the electrodes is shielded, a change in the capacitance of capacitor 2603 occurs, for example. The approach or contact of a sensor object can be detected by utilizing this change.

[0483] The current sensing circuit 2602 is a circuit for detecting changes in the current flowing through lines Y1 to Y6, which are caused by changes in the capacitance of the capacitor 2603. No change in the current value is detected in lines Y1 to Y6 if there is no approach or contact with a sensing object, whereas a decrease in the current value is detected if the capacitance decreases due to the approach or contact of a sensing object. It should be noted that an integrator circuit or similar is used to detect the current values.

[0484] Fig. 24B is a time diagram showing the input and output waveforms of the device in Fig. Figure 24A shows a mutually capacitive touch sensor. Fig. In 24B, a capture object is performed in all rows and columns within one frame period. Fig. 24B shows a period in which no object is detected (no touch), and a period in which an object is detected (touch). Fig. 24B shows the recorded current values ​​of lines Y1 to Y6 as waveforms of the voltage values.

[0485] A pulse voltage is applied sequentially to lines X1 to X6, and the waveforms of lines Y1 to Y6 change according to the pulse voltage. If there is no approach or contact with a detection object, the waveforms of lines Y1 to Y6 change uniformly according to the changes in the voltages of lines X1 to X6. The current value decreases at the point where a detection object approaches or makes contact, and the waveform of the voltage value changes accordingly.

[0486] By recording a change in mutual capacity in this way, the approach or contact of a recording object can be detected. <Beschreibung der Sensorschaltung>

[0487] Although Fig. Figure 24A shows a passive matrix touch sensor in which only the capacitor 2603 is provided as a touch sensor at the intersection of the lines, but an active matrix touch sensor comprising a transistor and a capacitor can also be used. Fig. Figure 25 represents an example of a sensor circuit included in an active matrix touch sensor.

[0488] The sensor circuit in Fig. 25 includes capacitor 2603 as well as transistors 2611, 2612 and 2613.

[0489] A signal G2 is input to a gate of transistor 2613. A voltage VRES is applied to one terminal of the source and drain of transistor 2613, and one electrode of capacitor 2603 and one gate of transistor 2611 are electrically connected to the other terminal of the source and drain of transistor 2613. One terminal of the source and drain of transistor 2611 is electrically connected to one terminal of the source and drain of transistor 2612, and a voltage VSS is applied to the other terminal of the source and drain of transistor 2611. A signal G1 is input to a gate of transistor 2612, and a line ML is electrically connected to the other terminal of the source and drain of transistor 2612. The voltage VSS is applied to the other electrode of capacitor 2603.

[0490] Next, the operating principle of the sensor circuit will be described in Fig. As described in section 25, first a potential is applied as signal G2 to switch on transistor 2613, thus applying a potential relative to the voltage VRES to node n, which is connected to the gate of transistor 2611. Then, a potential is applied as signal G2 to switch off transistor 2613, thereby maintaining the potential of node n.

[0491] Subsequently, the mutual capacitance of capacitor 2603 changes as a result of the approach or contact of a detection object, such as a finger; accordingly, the potential of node n of VRES is changed.

[0492] During a reading process, a potential is applied as signal G1 to switch on transistor 2612. Corresponding to the potential of node n, a current flows through transistor 2611, i.e., a current flows through line ML. By detecting this current, the approach or contact of a sensor object can be detected.

[0493] In each of the transistors 2611, 2612 and 2613, an oxide semiconductor layer is preferably used as the semiconductor layer in which a channel region is formed. In particular, such a transistor is preferably used for transistor 2613, so that the potential of node n can be maintained for a long time and the frequency of an operation to re-supply VRES to node n (update operation) can be reduced.

[0494] The structure described in this embodiment can be used in a suitable combination with any of the structures described in the other embodiments. (Version 7)

[0495] In this embodiment, a display module and electronic devices comprising a light-emitting element of an embodiment of the present invention are connected by means of Fig. 26, Fig. 27A to Fig. 27G, Fig. 28A to Fig. 28F as well Fig. 29A to Fig. 29D described. <Beschreibung des Anzeigemoduls>

[0496] With a display module 8000 in Fig. 26 are a touch sensor 8004 connected to an FPC 8003, a display device 8006 connected to an FPC 8005, a frame 8009, a printed circuit board 8010 and a battery 8011 arranged between an upper cover 8001 and a lower cover 8002.

[0497] The light-emitting element of an embodiment of the present invention can, for example, be used for the display device 8006.

[0498] The shapes and sizes of the upper cover 8001 and the lower cover 8002 can be changed as required according to the sizes of the touch sensor 8004 and the display device 8006.

[0499] The touch sensor 8004 can be a resistive touch sensor or a capacitive touch sensor and can be configured to overlap the display device 8006. A counter substrate (sealing substrate) of the display device 8006 can have a touch sensor function. A photosensor can be provided in each pixel of the display device 8006, thus obtaining an optical touch sensor.

[0500] Frame 8009 protects display device 8006 and also serves as an electromagnetic shield to block electromagnetic waves generated by the operation of printed circuit board 8010. Frame 8009 can also act as a radiation shield.

[0501] The 8010 printed circuit board includes a power supply circuit and a signal processing circuit for outputting a video signal and a clock signal. An external mains power supply or the separately supplied 8011 battery can be used to supply power to the power supply circuit. The 8011 battery can be omitted if a mains power supply is used.

[0502] The 8000 display module can also be equipped with a component such as a polarizing plate, a retardation plate or a prism foil. <Beschreibung des elektronischen Geräts>

[0503] Fig. 27A to Fig. 27G represents electronic devices. These electronic devices may include a housing 9000, a display section 9001, a loudspeaker 9003, operating buttons 9005 (including a power switch or an operating switch), a connection port 9006, a sensor 9007 (a sensor with a function for measuring or detecting force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electrical power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation), a microphone 9008, and the like. Furthermore, the sensor 9007 may have a function for measuring biological information, such as a pulse sensor and a fingerprint sensor.

[0504] The electronic devices that are in Fig. 27A to Fig. The functions shown in section 27G may include various features, such as a function for displaying different types of data (a still image, a moving image, a text image, and the like) on the display section, a touch sensor function, a function for displaying a calendar, date, time, and the like, a function for controlling processing with various types of software (programs), a wireless communication function, a function for connecting to different computer networks using a wireless communication function, a function for transmitting and receiving different types of data using a wireless communication function, a function for reading a program or data stored on a storage medium and displaying the program or data on the display section, and the like. It should be noted that functions that are for the purposes of the above are Fig. 27A to Fig. The electronic devices shown in section 27G are not limited to those described above, and the electronic devices may have additional functions. Although in Fig. 27A to Fig. Not shown in Section 27G, the electronic devices may include a variety of display sections. The electronic devices may include a camera or the like, as well as a function for capturing a still image, a function for capturing a moving image, a function for storing the captured image on a storage medium (an external storage medium or a storage medium built into the camera), a function for displaying the captured image on the display section, or the like.

[0505] The electronic devices that are in Fig. 27A to Fig. The items shown in section 27G are described in detail below.

[0506] Fig. Figure 27A is a perspective view of a portable information terminal 9100. The display section 9001 of the portable information terminal 9100 is flexible. Therefore, the display section 9001 can be installed along a curved surface of a curved housing 9000. The display section 9001 also includes a touch sensor, and operation can be performed by touching the screen with a finger, a stylus, or the like. For example, touching an icon displayed on the display section 9001 can launch an application.

[0507] Fig. Figure 27B is a perspective view of a portable information terminal 9101. The portable information terminal 9101 serves, for example, as one or more devices of a telephone, a notebook, and an information retrieval system. In particular, the portable information terminal can be used as a smartphone. It should be noted that the speaker 9003, the connection port 9006, the sensor 9007, and the like, which are shown in Fig. 27B not shown, in the portable information terminal 9101, as in the portable information terminal 9100, which is in Fig. The portable information terminal 9101 can be arranged as shown in Figure 27A. It can display text and image information on its various surfaces. For example, three control buttons 9050 (also called control icons, or simply icons) can be displayed on one surface of the display section 9001. Additionally, information 9051, represented by dashed rectangles, can be displayed on another surface of the display section 9001. Examples of the information 9051 include an indication of the arrival of an incoming email, a message from a social networking service (SNS), a call, and the like; the subject and sender of an email and an SNS message; the date; ...

Claims

[1] Light-emitting element (150; 250; 252; 260a; 260b; 262a; 262b), comprising: a light-emitting layer (120; 130; 160; 170; 180; 190), wherein the light-emitting layer (120; 130; 160; 170; 180; 190) comprises a first organic compound (131_1; 171_1), a second organic compound (131_2; 171_2) and a guest material (122; 132; 172), where a lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) is lower than a lowest unoccupied molecular orbital level of the second organic compound (131_2; 171_2), where a highest occupied molecular orbital level of the guest material (122; 132; 172) is higher than a highest occupied molecular orbital level of the second organic compound (131_2; 171_2), where an energy difference between a lowest unoccupied molecular orbital level of the guest material (122; 132; 172) and the highest occupied molecular orbital level of the guest material (122; 132; 172) is greater than an energy difference between the lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) and the highest occupied molecular orbital level of the second organic compound (131_2; 171_2), where the guest material (122; 132; 172) converts triplet excitation energy into a light emission, wherein the first organic compound (131_1; 171_1) and the second organic compound (131_2; 171_2) form an exciplex, wherein a maximum peak of an emission spectrum of a mixed thin film of the first organic compound (131_1; 171_1) and the second organic compound (131_2; 171_2) has a longer wavelength than a maximum peak of an emission spectrum of a thin film of the first organic compound (131_1; 171_1) and a maximum peak of an emission spectrum of a thin film of the second organic compound (131_2; 171_2), respectively, and wherein the first organic compound (131_1; 171_1) comprises a triazine skeleton. [2] Light-emitting element (150; 250; 252; 260a; 260b; 262a; 262b), comprising: a light-emitting layer (120; 130; 160; 170; 180; 190), wherein the light-emitting layer (120; 130; 160; 170; 180; 190) comprises a first organic compound (131_1; 171_1), a second organic compound (131_2; 171_2) and a guest material (122; 132; 172), where a lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) is lower than a lowest unoccupied molecular orbital level of the second organic compound (131_2; 171_2), where the highest occupied molecular orbital level of the first organic compound (131_1; 171_1) is lower than the highest occupied molecular orbital level of the second organic compound (131_2; 171_2), where the highest occupied molecular orbital level of the guest material (122; 132; 172) is higher than the highest occupied molecular orbital level of the second organic compound (131_2; 171_2), where an energy difference between a lowest unoccupied molecular orbital level of the guest material (122; 132; 172) and the highest occupied molecular orbital level of the guest material (122; 132; 172) is greater than an energy difference between the lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) and the highest occupied molecular orbital level of the second organic compound (131_2; 171_2), wherein the first organic compound (131_1; 171_1) comprises a triazine skeleton, where the guest material (122; 132; 172) converts triplet excitation energy into a light emission, wherein the first organic compound (131_1; 171_1) and the second organic compound (131_2; 171_2) form an exciplex, and wherein an energy difference between the lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) and the highest occupied molecular orbital level of the guest material (122; 132; 172) is greater than or equal to a transition energy calculated from an absorption edge of an absorption spectrum of the guest material (122; 132; 172). [3] Light-emitting element (150; 250; 252; 260a; 260b; 262a; 262b), comprising: a light-emitting layer (120; 130; 160; 170; 180; 190), wherein the light-emitting layer (120; 130; 160; 170; 180; 190) comprises a first organic compound (131_1; 171_1), a second organic compound (131_2; 171_2) and a guest material (122; 132; 172), where a lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) is lower than a lowest unoccupied molecular orbital level of the second organic compound (131_2; 171_2), where the highest occupied molecular orbital level of the first organic compound (131_1; 171_1) is lower than the highest occupied molecular orbital level of the second organic compound (131_2; 171_2), where the highest occupied molecular orbital level of the guest material (122; 132; 172) is higher than the highest occupied molecular orbital level of the second organic compound (131_2; 171_2), where an energy difference between a lowest unoccupied molecular orbital level of the guest material (122; 132; 172) and the highest occupied molecular orbital level of the guest material (122; 132; 172) is greater than an energy difference between the lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) and the highest occupied molecular orbital level of the second organic compound (131_2; 171_2), where the guest material (122; 132; 172) converts triplet excitation energy into a light emission, wherein the first organic compound (131_1; 171_1) and the second organic compound (131_2; 171_2) form an exciplex, wherein a maximum peak of an emission spectrum of a mixed thin film of the first organic compound (131_1; 171_1) and the second organic compound (131_2; 171_2) has a longer wavelength than a maximum peak of an emission spectrum of a thin film of the first organic compound (131_1; 171_1) and a maximum peak of an emission spectrum of a thin film of the second organic compound (131_2; 171_2), respectively, and wherein the first organic compound (131_1; 171_1) comprises a triazine skeleton. [4] Light-emitting element according to claim 1 or 3, wherein the energy difference between the lowest unoccupied molecular orbital level of the guest material (122; 132; 172) and the highest occupied molecular orbital level of the guest material (122; 132; 172) is greater by 0.3 eV or more than a transition energy calculated from an absorption edge of an absorption spectrum of the guest material (122; 132; 172). [5] Light-emitting element according to claim 2, wherein the energy difference between the lowest unoccupied molecular orbital level of the guest material (122; 132; 172) and the highest occupied molecular orbital level of the guest material (122; 132; 172) is greater by 0.3 eV or more than the transition energy calculated from the absorption edge of the absorption spectrum of the guest material (122; 132; 172). [6] Light-emitting element according to any one of claims 1 to 3, wherein the energy difference between the lowest unoccupied molecular orbital level of the guest material (122; 132; 172) and the highest occupied molecular orbital level of the guest material (122; 132; 172) is greater than a light emission energy of the guest material (122; 132; 172) by 0.3 eV or more. [7] Light-emitting element according to claim 1 or 3, wherein an emission spectrum of the exciplex comprises a region that overlaps an absorption band on a longest wavelength side of an absorption spectrum of the guest material (122; 132; 172). [8] Light-emitting element according to any one of claims 1 to 5 and 7, wherein the light emission energy of the guest material (122; 132; 172) is less than the energy difference between the lowest unoccupied molecular orbital level of the first organic compound (131_1; 171_1) and the highest occupied molecular orbital level of the second organic compound (131_2; 171_2). [9] Display device (600; 2501) comprising: the light-emitting element according to any one of claims 1 to 8; and a color filter and / or a transistor. [10] Electronic device comprising: the display device (600; 2501) according to claim 9; and a housing and / or a touch sensor. [11] Lighting device comprising: the light-emitting element (150; 250; 252; 260a; 260b; 262a; 262b) according to any one of claims 1 to 8; and a housing and / or a touch sensor.

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