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

Abstract

Light-emitting element (250) comprising: a light-emitting layer (120) between a pair of electrodes (102; 103); a host material (121); and a guest material (122), wherein the host material (121) comprises a first organic compound and a second organic compound, wherein the first organic compound is configured to emit thermally activated delayed fluorescence at room temperature, wherein the first organic compound and the second organic compound form an exciplex, and wherein the first organic compound comprises a π-electron-deficient heteroaromatic 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. State of the art

[0002] 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 electrodes of this element, light emission can be obtained from the light-emitting material.

[0003] Since the aforementioned light-emitting element is of a self-illuminating type, a display device using this light-emitting element offers the following advantages: good visibility, no need for backlighting, and low power consumption. Furthermore, such a light-emitting element is also advantageous in that it can be manufactured thin and lightweight and exhibits a high response speed.

[0004] In a light-emitting element (EL) whose EL layer contains an organic material as the light-emitting material and is positioned between a pair of electrodes (e.g., an organic EL cell), applying a voltage between the electrode pair causes electrons from a cathode and holes from an anode to be injected into the light-emitting EL layer, resulting in a current flow. 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.

[0005] 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 for the light-emitting element is 1:3. In other words, a light-emitting element containing a phosphorescent material has a higher light yield than a light-emitting element containing a fluorescent material.Consequently, light-emitting elements containing phosphorescent materials capable of converting the energy of a triplet excitation state into light emission have been actively developed in recent years (see, for example, patent document 1).

[0006] The energy required to excite an organic material depends on the energy of its singlet excitation state. In a light-emitting element containing a phosphorescent organic material, triplet excitation energy is converted into light emission energy. Consequently, if the energy difference between the singlet and triplet excitation states of an organic material is large, the energy required to excite the organic material is higher than the light emission energy by an amount equal to this energy difference. This difference between the energy required to excite the organic material and the light emission energy increases the drive voltage of the light-emitting element. Therefore, a method for suppressing this increase in the drive voltage has been developed (see patent document 2).

[0007] Among light-emitting elements containing phosphorescent materials, a light-emitting element that emits blue light, in particular, has not yet been used in practice because it is difficult to develop a stable material with a high triplet excitation energy level. For this reason, a light-emitting element containing a more stable fluorescent material has been developed, and a technique for increasing the light output of a light-emitting element containing a fluorescent material (a fluorescent element) has been investigated.

[0008] One of the materials that can partially convert the energy of the triplet excitation state into light emission is a thermally activated delayed fluorescent (TADF) emitter. In a TADF, a singlet excitation state is generated from a triplet excitation state through reverse intersystem crossing, and the singlet excitation state is converted into light emission.

[0009] To increase the light output of a light-emitting element using a thermally activated, delayed-fluorescence emitter, it is important not only for the efficient generation of a singlet excitation state from a triplet excitation state, but also for efficient emission from a singlet excitation state, i.e., a high fluorescence quantum yield. However, it is difficult to create a light-emitting material that fulfills both of these requirements.

[0010] Patent document 3 discloses a method: In a light-emitting element containing a thermally activated delayed-release (TADF) emitter and a fluorescent material, singlet excitation energy from the TADF is transferred to the fluorescent material, and light emission is obtained from the fluorescent material. Non-patent document 1 discloses a light-emitting element containing a host material acting as a TADF emitter in the light-emitting layer. Further exemplary light-emitting elements are disclosed in patent documents 4 to 8. [Reference] [Patent document 1] JP 2010 - 182 699 A [Patent document 2] JP 2012 - 212 879 A [Patent Document 3] JP 2014 - 451 79 A [Patent document 4] US 2014 / 0 034 930 A1 [Patent document 5] US 2014 / 0 080 237 A1 [Patent Document 6] WO 2013 / 056 776 A1 [Patent document 7] US 2014 / 0 091 293 A1 [Patent document 8] US 2013 / 0 207 088 A1 [Non-patent document 1] H. Nakanotani et al., Nature Communications 2014, 5(1), 1-7. Disclosure of the invention

[0011] In a light-emitting element containing a thermally activated, delayed fluorescent emitter and a light-emitting material, charge carriers preferably recombine efficiently in the thermally activated, delayed fluorescent emitter to increase the light output or reduce the drive voltage.

[0012] To increase the light output of a light-emitting element containing a thermally activated, delayed-release fluorescent emitter and a fluorescent material, efficient generation of a singlet excitation state from a triplet excitation state is preferred. Furthermore, efficient energy transfer from a singlet excitation state of the thermally activated, delayed-release fluorescent emitter to a singlet excitation state of the fluorescent material is preferred.

[0013] In light of the foregoing, one object of an embodiment of the present invention is to provide a light-emitting element that contains a fluorescent or phosphorescent material and has a high luminous efficacy. Another object of an embodiment of the present invention is to provide a light-emitting element with low power consumption. 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.

[0014] It should be noted that the description of the preceding problem does not preclude the existence of further problems. In one embodiment of the present invention, it is unnecessary to fulfill all problems. Problems other than those stated above will become apparent from the explanation of the description and the like, and can be derived from it.

[0015] In one embodiment of the present invention, a light-emitting element comprises a light-emitting layer between a pair of electrodes, a host material, and a guest material, wherein the host material comprises a first organic compound and a second organic compound, wherein the first organic compound is configured to emit thermally activated delayed fluorescence at room temperature, wherein the first organic compound and the second organic compound form an exciplex, and wherein the first organic compound comprises a π-electron-deficient heteroaromatic framework.

[0016] In a further embodiment of the present invention, a light-emitting element comprises a light-emitting layer between a pair of electrodes, a host material and a guest material, wherein the host material comprises a first organic compound and a second organic compound, wherein in the first organic compound there is a difference between a singlet excitation energy level and a triplet excitation energy level greater than 0 eV and less than or equal to 0.2 eV, wherein the first organic compound and the second organic compound form an exciplex, and wherein the first organic compound comprises a π-electron-deficient heteroaromatic framework.

[0017] In each of the aforementioned structures, the exciplex preferably has a function for emitting thermally activated delayed fluorescence at room temperature. Furthermore, the exciplex preferably has a function for supplying excitation energy to the guest material. An emission spectrum of the exciplex preferably also includes a region that overlaps with an absorption band on the lowest energy side of an absorption spectrum of the guest material.

[0018] In each of the above structures, the first organic compound has a function to emit thermally activated delayed fluorescence at room temperature.

[0019] In each of the aforementioned structures, one of the first organic compound and the second organic compound preferably has a hole-transporting function, and the other of the first organic compound and the second organic compound preferably has an electron-transporting function. Furthermore, the second organic compound preferably comprises a π-electron-rich heteroaromatic framework and / or an aromatic amine framework. The first organic compound also preferably comprises a π-electron-rich heteroaromatic framework and / or an aromatic amine framework in addition to the π-electron-deficient heteroaromatic framework.

[0020] In each of the above structures, the π-electron-rich heteroaromatic framework preferably comprises one or more of the following: an acridine framework, a phenoxazine framework, a phenothiazine framework, a furan framework, a thiophene framework, and a pyrrole framework; and the π-electron-poor heteroaromatic framework preferably comprises a diazine framework or a triazine framework. Furthermore, the pyrrole framework preferably comprises an indole framework, a carbazole framework, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole framework.

[0021] In another embodiment of the present invention, a display device comprises the light-emitting element with one of the structures described above, as well as a color filter and / or a transistor. In another embodiment of the present invention, an electronic device comprises the display device described above, as well as a housing and / or a touch sensor. In another embodiment of the present invention, a lighting device comprises the light-emitting element with one of the structures described above, as well as a housing and / or a touch sensor. The category of one embodiment 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 therefore refers to an image display device and a light source (e.g., a lighting device). The light-emitting device may be contained in a display module in which a connector, such as a flexible printed circuit (FPC) or a tape carrier package (TCP), is connected to a light-emitting device; in a display module in which a printed circuit board is provided at the end of a TCP; or in a display module in which an integrated circuit (IC) is mounted directly onto a light-emitting element by a chip-on-glass (COG) process.

[0022] According to one embodiment of the present invention, a light-emitting element can be provided which contains a fluorescent or phosphorescent material exhibiting high luminous efficacy. According to one embodiment of the present invention, a light-emitting element with low power consumption can be provided. According to one embodiment of the present invention, a novel light-emitting element can be provided. According to one embodiment of the present invention, a novel light-emitting device can be provided. According to one embodiment of the present invention, a novel display device can be provided.

[0023] It should be noted that the description of these effects does not preclude the existence of further effects. An embodiment of the present invention need not necessarily exhibit all of the effects mentioned 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

[0024] In the accompanying drawings: Fig. 1A and Fig. Figure 1B shows schematic cross-sectional views of a light-emitting element of an embodiment of the present invention, and Fig. Figure 1C shows the correlation between energy levels in a light-emitting layer; Fig. 2A and Fig. Figures 2B show the correlation between energy bands in a light-emitting layer of a light-emitting element of an embodiment of the present invention; Fig. 3A to Fig. Figures 3C each show the correlation between energy levels in a light-emitting layer of a light-emitting element of an embodiment of the present invention; Fig. 4A and Fig. Figures 4B are schematic cross-sectional views of a light-emitting element of an embodiment of the present invention, and Fig. 4C shows the correlation between energy levels in a light-emitting layer; Fig. 5A and Fig. Figure 5B are schematic cross-sectional views of a light-emitting element of an embodiment of the present invention, and Fig. 5C shows the correlation between energy levels in a light-emitting layer; Fig. 6A and Fig. Figures 6B are each a schematic cross-sectional view of a light-emitting element of an embodiment of the present invention; Fig. 7A and Fig. Figures 7B are each a schematic cross-sectional view of a light-emitting element of an embodiment of the present invention; Fig. 8A and Fig. Figures 8B are each a schematic cross-sectional view of a light-emitting element of an embodiment of the present invention; Fig. 9A to Fig. Figures 9C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting element of an embodiment of the present invention; Fig. 10A to Fig. Figures 10C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting element of an embodiment of the present invention; Fig. 11A and Fig. Figures 11B are a top view and 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. Figure 13 is a schematic cross-sectional view representing a display device of an embodiment of the present invention; Fig. 14A and Fig. Figures 14B are schematic cross-sectional views, each representing a display device of an embodiment of the present invention; Fig. 15A and Fig. Figures 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. Figures 17B are schematic cross-sectional views, each representing a display device of an embodiment of the present invention; Fig. Figure 18 is a schematic cross-sectional view representing a display device of an embodiment of the present invention; Fig. 19A and Fig. Figures 19B are schematic cross-sectional views, each representing a display device of an embodiment of the present invention; Fig. 20A and Fig. 20B are a block diagram and a circuit diagram representing a display device of an embodiment of the present invention; Fig. 21A and Fig. 21B are circuit diagrams, each representing a pixel circuit of a display device of an embodiment of the present invention; Fig. 22A and Fig. 22B are circuit diagrams, each representing a pixel circuit of a display device of an embodiment of the present invention; Fig. 23A and Fig. Figures 23B are perspective views of an example of a touchscreen of an embodiment of the present invention; Fig. 24A to Fig. Figures 24C are cross-sectional views of examples of a display device and a touch sensor of an embodiment of the present invention; Fig. 25A and Fig. Figures 25B are cross-sectional views of examples of a touchscreen of an embodiment of the present invention; Fig. 26A and Fig. Figures 26B are a block diagram and a timing diagram of a touch sensor of an embodiment of the present invention; Fig. 27 is a circuit diagram of a touch sensor of an embodiment of the present invention; Fig. Figure 28 is a perspective view showing a display module of an embodiment of the present invention; Fig. 29A to Fig. 29G represent electronic devices of an embodiment of the present invention; Fig. 30A to Fig. 30D represent electronic devices of an embodiment of the present invention; Fig. 31A and Fig. Figures 31B are perspective views showing a display device of an embodiment of the present invention; Fig. 32A to Fig. Figures 32C are a perspective view and cross-sectional views depicting light-emitting devices of an embodiment of the present invention; Fig. 33A and Fig. Figures 33D are cross-sectional views, each representing a light-emitting device of an embodiment of the present invention; Fig. 34A to Fig. 34C represent an electronic device and a lighting device of an embodiment of the present invention; Fig. 35 represents lighting devices of an embodiment of the present invention; Fig. 36A and Fig. Figure 36B shows the luminance-current density properties of light-emitting elements of an example; Fig. 37A and Fig. Figure 37B shows the luminance-voltage properties of light-emitting elements of an example; Fig. 38A and Fig. Figure 38B shows the power efficiency-luminance properties of light-emitting elements of an example; Fig. 39A and Fig. Figure 39B shows the power efficiency-luminance properties of light-emitting elements of an example; Fig. 40A and Fig. Figure 40B shows the external quantum efficiency luminance properties of light-emitting elements of an example; Fig. 41A and Fig. Figure 41B shows the electroluminescence spectra of light-emitting elements of an example; Fig. Figure 42 shows the emission spectra of a thin film of an example; Fig. Figure 43 shows the emission spectra of a thin film of an example; Fig. Figure 44 shows the emission spectra of a thin film of an example; Fig. Figure 45 shows the emission spectra of a thin film of an example; Fig. Figure 46 shows the emission spectra of a thin film of an example; Fig. Figure 47 shows the emission spectra of a thin film of an example; Fig. Figure 48 shows the emission spectra of a thin film of an example; Fig. 49A and Fig. 49B shows NMR diagrams of a compound from a reference example; Fig. Figure 50 shows an NMR diagram of a compound from a reference example; and Fig. Figure 51 shows an NMR diagram of a compound of a reference example. Best method for implementing the invention

[0025] Embodiments of the present invention are described below with reference to the drawings. However, the present invention is not limited to the following description, and it is readily apparent that 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.

[0026] It should be noted that, for the sake of simplicity, the position, size, area, or the like of any structure depicted in drawings and the like is not always shown precisely. The disclosed invention is therefore not necessarily limited to the position, size, area, or the like disclosed in the drawings and the like.

[0027] It should be noted that the ordinal numbers, such as "first," "second," and the like, are used in this description and the like for convenience only, and they do not indicate the sequence of steps or the order of layers. Therefore, for example, an appropriate description may still be given 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.

[0028] In the explanations of the modes of the present invention in this description and the like, based on the drawings, in some cases the same components in different drawings are generally provided with the same reference numerals.

[0029] In this description and similar texts, the terms "film" and "layer" may be used interchangeably depending on the context or circumstances. For example, in some cases the term "conducting layer" may be changed to "conducting film." Similarly, in some cases the term "insulating film" may be changed to "insulating layer."

[0030] In this description and similar texts, a singlet excitation state (S*) denotes a singlet state with a given excitation energy. An S1 level refers to the lowest level of singlet excitation energy, i.e., the lowest level of excitation energy in a singlet excitation state. A triplet excitation state (T*) denotes a triplet state with a given excitation energy. A T1 level refers to the lowest level of triplet excitation energy, i.e., the lowest level of excitation energy in a triplet excitation state. It should be noted that in this description and similar texts, simple expressions such as "singulet excitation state" and "singulet excitation energy level" sometimes refer to the lowest singlet excitation state or the S1 level, respectively.Furthermore, in some cases, simple expressions such as "triplet excitation state" and "triplet excitation energy level" refer to the lowest triplet excitation state or the T1 level.

[0031] 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.

[0032] Thermally activated delayed fluorescent emission energy can be derived from an emission peak (including a shoulder) on the shortest wavelength side of the thermally activated delayed fluorescence. Phosphorescence emission energy or triplet excitation energy can be derived from an emission peak (including a shoulder) on the shortest wavelength side of the phosphorescence emission. It should be noted that phosphorescence emission can be observed in a low-temperature environment (e.g., 10 K) by time-resolved photoluminescence.

[0033] 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.

[0034] 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 490 nm, and blue light emission refers to light emission with at least one emission spectrum peak in that wavelength range. A wavelength range of green refers to a wavelength range greater than or equal to 490 nm and less than 580 nm, and green light emission refers to light emission with at least one emission spectrum peak in that wavelength range. A wavelength range of red refers to a wavelength range greater than or equal to 580 nm and less than 680 nm, and red light emission refers to light emission with at least one emission spectrum peak in that wavelength range. (Version 1)

[0035] In this embodiment, a light-emitting element of an embodiment of the present invention is described below by reference to Fig. 1A to Fig. 1C, Fig. 2A and Fig. 2B as well as Fig. 3A to Fig. 3C described. <Strukturbeispiel des Licht emittierenden Elements>

[0036] First, a structure of the light-emitting element of an embodiment of the present invention will be described below based on Fig. 1A to Fig. 1C described.

[0037] Fig. Figure 1A is a schematic cross-sectional view of a light-emitting element 150 of an embodiment of the present invention.

[0038] 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.

[0039] 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.

[0040] 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 order 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.

[0041] The structure of EL layer 100 is not limited to the structure described in Fig. Figure 1A shows 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. Alternatively, the EL layer 100 can, for example, comprise a functional layer capable of lowering a hole or electron injection barrier, improving a hole or electron transport property, inhibiting a hole or electron transport property, or suppressing an electrode quenching effect. It should be noted that the functional layers can each be a single layer or a multiple layer.

[0042] 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.

[0043] The guest material 132 can be a light-emitting organic material, and the light-emitting organic material is preferably a material capable of emitting fluorescence (hereinafter also referred to as the fluorescent material). A structure in which a fluorescent material is used as the guest material 132 is described below. The guest material 132 can also be referred to as the fluorescent material.

[0044] In the light-emitting element 150 of an embodiment of the present invention, applying a voltage between the pair of electrodes (electrodes 101 and 102) causes electrons and holes to be injected from the cathode and the anode, respectively, into the EL layer 100, thereby generating a current. Excitons are formed by recombination of the injected electrons and holes. The ratio of singlet excitons to triplet excitons (hereinafter referred to as the exciton generation probability) generated by the recombination of charge carriers (electrons and holes) is, according to the statistically obtained probability, approximately 1:3.Accordingly, for a light-emitting element containing a fluorescent material, the probability of generating singlet excitons that contribute to light emission is 25%, and the probability of generating triplet excitons that do not contribute to light emission is 75%. Therefore, to increase the light output of the light-emitting element, it is important to convert the triplet excitons that do not contribute to light emission into singlet excitons that do contribute to light emission. <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] The combination of organic compound 131_1 and organic compound 131_2 is acceptable as long as it can form an exciplex; 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 preferably fulfills the following: The highest occupied molecular orbital (HOMO) level of one of organic compound 131_1 and organic compound 131_2 is higher than or equal to the HOMO level of the other organic compound; and the lowest unoccupied molecular orbital (LUMO) level of one of the organic compounds is higher than or equal to the LUMO level of the other organic compound.

[0049] For example, if organic compound 131_1 has a hole transport property and organic compound 131_2 has an electron transport property, the HOMO level of organic compound 131_1 is preferably higher than or equal to the HOMO level of organic compound 131_2, and the LUMO level of organic compound 131_1 is preferably higher than or equal to the LUMO level of organic compound 131_2, as shown in an energy band diagram in Fig. 2A. Alternatively, if organic compound 131_2 has a hole transport property and organic compound 131_1 has an electron transport property, the HOMO level of organic compound 131_2 is preferably higher than or equal to the HOMO level of organic compound 131_1, and the LUMO level of organic compound 131_2 is preferably higher than or equal to the LUMO level of organic compound 131_1, as shown in an energy band diagram in Fig. Figure 2B illustrates this. In this case, an exciplex formed by organic compound 131_1 and organic compound 131_2 has an excitation energy that essentially corresponds to an energy difference between the HOMO level of one of the organic compounds and the LUMO level of the other organic compound. Furthermore, the difference between the HOMO level of organic compound 131_1 and the HOMO level of organic compound 131_2, as well as the difference between the LUMO level of organic compound 131_1 and the LUMO level of organic compound 131_2, are each preferably 0.2 eV or more, more preferably 0.3 eV or more. Fig. 2A and Fig. 2B represents “host” (131_1) and “host” (131_2) the organic compound 131_1 and the organic compound 131_2, respectively.

[0050] According to the relationship between the HOMO level and the LUMO level described above, the combination of organic compound 131_1 and organic compound 131_2 preferably fulfills the following: The oxidation potential of one of the organic compounds 131_1 and organic compound 131_2 is higher than or equal to the oxidation potential of the other organic compound; and the reduction potential of one of the organic compounds is higher than or equal to the reduction potential of the other organic compound.

[0051] For example, if organic compound 131_1 has hole transport properties and organic compound 131_2 has electron transport properties, the oxidation potential of organic compound 131_1 is preferably lower than or equal to the oxidation potential of organic compound 131_2, and the reduction potential of organic compound 131_1 is preferably lower than or equal to the reduction potential of organic compound 131_2. Alternatively, if organic compound 131_2 has hole transport properties and organic compound 131_1 has electron transport properties, the oxidation potential of organic compound 131_2 is preferably lower than or equal to the oxidation potential of organic compound 131_1, and the reduction potential of organic compound 131_2 is preferably lower than or equal to the reduction potential of organic compound 131_1.It should be noted that the oxidation potentials and the reduction potentials can be measured using a cyclic voltammetry (CV) method.

[0052] 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 by adjusting 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.

[0053] Organic compound 131_1 is preferably a thermally activated, delayed-release fluorescent emitter. Alternatively, organic compound 131_1 preferably has a function for emitting thermally activated delayed-release fluorescence at room temperature. That is, organic compound 131_1 is a material that can spontaneously generate a singlet excitation state from a triplet excitation state by reverse intersystem crossing. Therefore, the difference between the singlet excitation energy level and the triplet excitation energy level is preferably greater than 0 eV and less than or equal to 0.2 eV. It should be noted that organic compound 131_1 is not necessarily a thermally activated, delayed-release fluorescent emitter, as long as it has a function for converting triplet excitation energy to singlet excitation energy.

[0054] Furthermore, the organic compound 131_1 preferably comprises a framework with hole transport properties and a framework with electron transport properties. The organic compound 131_1 also preferably comprises a π-electron-rich heteroaromatic framework and / or an aromatic amine framework, as well as a π-electron-poor heteroaromatic framework. Moreover, the π-electron-rich heteroaromatic framework is particularly preferably directly bonded to the π-electron-poor heteroaromatic framework, in which case both the donor properties of the π-electron-rich heteroaromatic framework and the acceptor properties of the π-electron-poor heteroaromatic framework are improved, and the difference between the singlet excitation energy level and the triplet excitation energy level becomes small.If organic compound 131_1 has strong donor and acceptor properties, a donor-acceptor exciplex is readily formed by organic compound 131_1 and organic compound 131_2.

[0055] Furthermore, the overlap between a region containing the HOMO and a region containing the LUMO in organic compound 131_1 is preferably small. It should be noted that a molecular orbital describes the spatial distribution of electrons in a molecule and can indicate the probability of finding electrons. The molecular orbital allows for a detailed description of the electron configuration of the molecule (the spatial distribution and energy of the electrons).

[0056] 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; therefore, the overlap between the HOMO and the LUMO is very small. This means that the exciplex has a small difference between the singlet and triplet excitation energy levels. Therefore, the difference between the triplet and singlet excitation energy levels of the exciplex formed by organic compounds 131_1 and 131_2 is preferably greater than 0 eV and less than or equal to 0.2 eV.

[0057] Fig. Figure 1C shows a correlation between the energy levels of organic compound 131_1, organic compound 131_2, and guest material 132 in the light-emitting layer 130. The following explains the terms and symbols in Fig. 1C represents: 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 fluorescent material); S H1 : the S1 level of the host material (of the organic compound 131_1); T H1 : the T1 level of the host material (of the organic compound 131_1); S H2 : the S1 level of the host material (of the organic compound 131_2); T H2 : the T1 level of the host material (of the organic compound 131_2); S G : the S1 level of guest material 132 (the fluorescent material); T G : the T1 level of guest material 132 (the fluorescent material); S E : the S1 level of the exciplex; and T E : the T1 level of the exciplex.

[0058] 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 (S E ) of the exciplex and the T1 level (T E The energy levels of the exciplex are adjacent to each other (see Route E3 in Fig. 1C).

[0059] 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 then function as the original two 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 accepts a hole and the other substance accepts an electron, and they interact to readily form an exciplex.In this case, any one of the substances can form an exciplex without itself forming an excited state; accordingly, most of the excited states formed in the light-emitting layer 130 can exist as exciplexes. The excited state of the host material 131 can be formed with a lower excitation energy, since the excitation energy levels (p. E and T E ) of the exciplex are lower than the S1 levels (S H1 and S H2 ) of the organic compounds (organic compound 131_1 and organic compound 131_2) that form the exciplex. Accordingly, the drive voltage of the light-emitting element 150 can be reduced.

[0060] Since the S1 level (S E ) and the T1 level (T ESince the exciplex's ionic pathways are located close together, the exciplex exhibits a function for emitting thermally activated delayed fluorescence. In other words, the exciplex exhibits a function for converting triplet excitation energy to singlet excitation energy through reverse intersystem crossing (upward conversion) (see Route E4 in [reference]). Fig. 1C). Thus, the triplet excitation energy generated in the light-emitting layer 130 is partially converted into singlet excitation energy by the exciplex. To bring about this conversion, the energy difference between the singlet excitation energy level (S) E ) and the triplet excitation energy level (T E ) of the exciplex preferably greater than 0 eV and less than or equal to 0.2 eV.

[0061] Furthermore, the S1 level (S E ) of the exciplex preferably higher than the S1 level (S G) of the guest material 132. In this way, the singlet excitation energy of the formed exciplex can be reduced from the S1 level (S E ) of the exciplex to the S1 level (S G ) of guest material 132 are transferred, so that guest material 132 is put into the singlet excitation state, resulting in light emission (see Route E5 in Fig. 1C).

[0062] In order to obtain efficient light emission from the singlet excitation state of the guest material 132, the fluorescence quantum yield of the guest material 132 is preferably high, in particular 50% or higher, more preferably 70% or higher, and even more preferably 90% or higher.

[0063] It should be noted that the T1 level (T E ) of the exciplex preferably lower than the T1 levels (T H1 and T H2) of the organic compounds forming the exciplex (organic compound 131_1 and organic compound 131_2) to efficiently bring about reverse intersystem crossing. Thus, it is less likely that the triplet excitation energy of the exciplex will be quenched due to the organic compounds, leading to efficient induction of reverse intersystem crossing.

[0064] For example, if there is a large difference between the S1 level and the T1 level in at least one of the connections forming an exciplex, the T1 level (T EThe S1 level of the exciplex is equal to an energy level lower than the T1 level of each compound. Furthermore, the difference between the S1 level and the T1 level of the exciplex is preferably small, and the S1 level of the guest material is preferably lower than the S1 level of the exciplex. Therefore, it is difficult to use a material with a high singlet excitation energy level, i.e., a material that emits light with a high emission energy, such as blue light, as guest material 132 if the difference between the S1 level and the T1 level of at least one of the compounds is large.

[0065] However, in the organic compound 131_1 of an embodiment of the present invention, there is a difference between the S1 level (S H1 ) and the T1 level (T H1) small. Therefore, both the S1 level and the T1 level of the organic compound 131_1 can be increased simultaneously, and the T1 level of the exciplex can be increased. Consequently, an embodiment of the present invention, without being limited to the emission color of the guest material 132, can be used with any light-emitting element that emits various types of light, ranging from light with a high emission energy, such as blue light, to light with a low emission energy, such as red light.

[0066] If organic compound 131_1 comprises a framework with strong donor properties, a hole injected into the light-emitting layer 130 is readily injected into and transported into organic compound 131_1. At this point, organic compound 131_2 preferably comprises an acceptor framework exhibiting stronger acceptor properties than an acceptor framework of organic compound 131_1. Consequently, organic compound 131_1 and organic compound 131_2 readily form an exciplex. Alternatively, 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 into organic compound 131_1.At this stage, organic compound 131_2 preferably comprises a donor scaffold that exhibits stronger donor properties than a donor scaffold of organic compound 131_1. Consequently, organic compound 131_1 and organic compound 131_2 readily form an exciplex.

[0067] It should be noted that if organic compound 131_1 has a function for converting the triplet excitation energy into the singlet excitation energy spontaneously by reverse intersystem crossing, and organic compound 131_1 and organic compound 131_2 do not readily form an exciplex, e.g., if the HOMO level of organic compound 131_1 is higher than that of organic compound 131_2 and the LUMO level of organic compound 131_2 is higher than that of organic compound 131_1, then both the electron and the hole, which are charge carriers that have been injected into the light-emitting layer 130, are readily injected and transported into organic compound 131_1. In this case, the charge carrier balance in the light-emitting layer 130 must be controlled by the hole transport property and the electron transport property of the organic compound 131_1.Therefore, in addition to having a function for converting triplet excitation energy into singlet excitation energy, organic compound 131_1 must itself possess a molecular structure with a suitable charge carrier balance, which makes constructing the molecular structure difficult. In contrast, in one embodiment of the present invention, an electron is injected and transported into one of organic compounds 131_1 and organic compound 131_2, and a hole is injected and transported into the other; thus, the charge carrier balance can be easily controlled by adjusting the mixing ratio, and a light-emitting element with high luminous efficacy can be provided.

[0068] Alternatively, if, for example, the HOMO level of organic compound 131_2 is higher than that of organic compound 131_1 and the LUMO level of organic compound 131_1 is higher than that of organic compound 131_2, both the electron and the hole, which are charge carriers injected into the light-emitting layer 130, are readily injected and transported into organic compound 131_2. Thus, the charge carriers readily recombine in organic compound 131_2. In the case where organic compound 131_2 lacks a function for converting triplet excitation energy to singlet excitation energy on its own through reverse intersystem crossing, it is difficult to convert the triplet excitation energy of an exciton directly formed by charge carrier recombination into singlet excitation energy.Therefore, it is difficult to use exciton energies other than the singlet excitation energy, which is directly generated by charge carrier recombination, for light emission. In contrast, in one embodiment of the present invention, organic compound 131_1 and organic compound 131_2 can form an exciplex, and the triplet excitation energy can be converted into the singlet excitation energy by reverse intersystem crossing. Therefore, a light-emitting element with high luminous efficacy and high reliability can be provided.

[0069] Fig. Figure 1C shows the case in which the S1 level of organic compound 131_2 is higher than that of organic compound 131_1 and the T1 level of organic compound 131_1 is higher than that of organic compound 131_2; however, an embodiment of the present invention is not limited to this. For example, as shown in Fig. 3A, the S1 level of organic compound 131_1 may be higher than that of organic compound 131_2, and the T1 level of organic compound 131_1 may be higher than that of organic compound 131_2. Alternatively, as in Fig. 3B, the S1 level of organic compound 131_1 is essentially the same as that of organic compound 131_2. Alternatively, as in Fig. 3C, the S1 level of organic compound 131_2 is higher than that of organic compound 131_1, and the T1 level of organic compound 131_2 can be higher than that of organic compound 131_1. It should be noted that in each case, the T1 level of the exciplex is preferably lower than the T1 level of each of the organic compounds forming the exciplex (organic compound 131_1 and organic compound 131_2) in order to efficiently bring about reverse intersystem crossing. It should be noted that in the process of exciplex formation, the following steps are effective in increasing efficiency: First, reverse intersystem crossing occurs in organic compound 131_1; the singlet excitation state (with an energy level of S) H1 ) of the organic compound 131_1 is increased; and the singlet exciplex (with an energy level of S E) is formed (after which the energy is transferred to the guest). In this case, the T1 level (T H2 ) of the organic compound 131_2 preferably higher than the T1 level (T H1 ) of the organic compound 131_1; thus the structure in Fig. 3C preferred.

[0070] It should be noted that, since a direct transition from a singlet ground state to a triplet excited state is forbidden in guest material 132, it is unlikely that an energy transfer from the S1 level (S E ) of the exciplex to the T1 level (T G ) of the guest material 132 is a major energy transfer process.

[0071] If a transfer of the triplet excitation energy from the T1 level (T E ) of the exciplex to the T1 level (T G ) of guest material 132 occurs, the triplet excitation energy is deactivated (see route Es in Fig. 1C). Therefore, it is preferably less likely that energy transfer via route E6 will occur, as the efficiency of generating the triplet excitation state of the guest material 132 and thermal deactivation can be reduced. To satisfy this condition, the weight ratio of the guest material 132 to the host material 131 is preferably low, in particular preferably greater than or equal to 0.001 and less than or equal to 0.05, more preferably greater than or equal to 0.001 and less than or equal to 0.03, more preferably greater than or equal to 0.001 and less than or equal to 0.01.

[0072] It should be noted that if the direct charge carrier recombination process is dominant in the guest material 132, many triplet excitons are generated in the light-emitting layer 130, leading to a reduced light yield due to thermal deactivation. Therefore, the probability of the energy transfer process through the exciplex formation process (routes E4 and E5 in [reference]) is preferable. Fig. 1C) higher than the probability of the direct charge carrier recombination process in the guest material 132, since the efficiency of generating the triplet excitation state of the guest material 132 and thermal deactivation can be reduced. Therefore, as described above, the weight ratio of the guest material 132 to the host material 131 is preferably low, in particular preferably greater than or equal to 0.001 and less than or equal to 0.05, more preferably greater than or equal to 0.001 and less than or equal to 0.03, more preferably greater than or equal to 0.001 and less than or equal to 0.01.

[0073] By ensuring that all energy transfer processes of routes E4 and E5 occur efficiently in the manner described above, both the singlet excitation energy and the triplet excitation energy of the host material 131 can be efficiently converted into the singlet excitation energy of the guest material 132, enabling the light-emitting element 150 to emit light with high luminous efficacy.

[0074] The processes described above via routes E3, E4, and E5 can be referred to in this description and the like as exciplex singlet energy transfer (ExSET) or exciplex-enhanced fluorescence (ExEF). In other words, in the light-emitting layer 130, the excitation energy is transferred from the exciplex to the guest material 132.

[0075] 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>

[0076] 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). Although the intermolecular energy transfer process between host material 131 and guest material 132 is described here, the same applies to a case where host material 131 is an exciplex. <<Förster-Mechanismus> >

[0077] In the Förster mechanism, energy transfer does not require direct contact between molecules. Instead, energy is transferred through 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 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). kh*→g=9000c4K2ϕln10128π5n4NτR6∫f'h(ν)εg(ν)ν4dν

[0078] In formula (1), v represents a frequency, f' h(v) represents a normalized emission spectrum of the host material 131 (a fluorescence spectrum for energy transfer from a singlet excitation state, and a phosphorescence spectrum for 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 an energy transfer from a singlet excitation state, and a phosphorescence quantum yield for an energy transfer from a triplet excitation state), and K 2represents a coefficient (0 to 4) for the orientation of a transition dipole moment between the host material 131 and the guest material 132. It should be noted that for random orientation K 2 is equal to 2 / 3. < <dexter-mechanismus>>

[0079] In the Dexter mechanism, the host material 131 and the guest material 132 are located near a contact-effective region where their orbitals overlap. 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 energy transfer. It should be noted that the rate constant k h * →g the Dexter mechanism is represented by formula (2). kh*→g=(2πh)K2exp(−2RL)∫f'h(ν)ε'g(ν)dν

[0080] 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 for energy transfer from a singlet excitation state, and a phosphorescence spectrum for 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.

[0081] 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 during energy transfer from a singlet excitation state, and phosphorescence during energy transfer from a triplet excitation state) of the host material 132, 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. ϕET=kh*→gkr+kn+kh*→g=kh*→g(1τ)+kh*→g

[0082] Formula (3) shows that the energy transfer efficiency ϕ ET by increasing the velocity constant k h * →g during energy transfer, so that another competing rate constant k r + k n (= 1 / τ) becomes relatively small. <<Konzept zur Förderung der Energieübertragung> >

[0083] First, energy transfer via the Förster mechanism is considered. Substituting formula (1) into formula (3) allows τ to be eliminated. Thus, for the Förster mechanism, the energy transfer efficiency ϕ depends on... ET does not depend on the lifetime τ of the excitation state of the host material 131. Furthermore, it can be stated that the energy transfer efficiency ϕ ET The luminescence quantum yield ϕ (here the fluorescence quantum yield, because it involves energy transfer from a singlet excitation state) is higher. The luminescence quantum yield of an organic compound in a triplet excitation state is generally very low at room temperature. Therefore, if the host material 131 is in a triplet excitation state, an energy transfer process via the Förster mechanism can be ignored, and an energy transfer process via the Förster mechanism is only considered if the host material 131 is in a singlet excitation state.

[0084] Furthermore, the emission spectrum (the fluorescence spectrum in the case of energy transfer from a singlet excitation state) of the host material 131 preferably overlaps to a large extent with the absorption spectrum (absorption corresponding to the transition from the singlet ground state to the singlet excitation state) of the guest material 132. It is also preferred that the molar absorption coefficient of the guest material 132 is also high. That is, the emission spectrum of the host material 131 overlaps with the absorption band of the guest material 132, which is located on the longest wavelength side. Since a direct transition from the singlet ground state to the triplet excitation state of the guest material 132 is forbidden, the molar absorption coefficient of the guest material 132 in the triplet excitation state can be ignored.Thus, the Förster mechanism can ignore a process of energy transfer to a triplet excitation state of the host material 132, and only a process of energy transfer to a singlet excitation state of the host material 132 is considered. That is, the Förster mechanism considers a process of energy transfer from the singlet excitation state of the host material 131 to the singlet excitation state of the host material 132.

[0085] Next, energy transfer via the Dexter mechanism is considered. According to formula (2), it is preferable that, in order to determine the rate constant k h * →g To increase the energy transfer efficiency, the emission spectrum of the host material 131 (a fluorescence spectrum in the case of energy transfer from a singlet excitation state) preferably overlaps largely with an absorption spectrum of the guest material 132 (absorption corresponding to the transition from a singlet ground state to a singlet excitation state). Therefore, the energy transfer efficiency can be optimized by ensuring that the emission spectrum of the host material 131 overlaps with the absorption band of the guest material 132 located on the longest wavelength side.

[0086] When formula (2) is substituted into formula (3), it is found that the energy transfer efficiency ϕ ET in the Dexter mechanism depends on τ. In the Dexter mechanism, which is a process of energy transfer based on electron exchange, energy transfer from the triplet excitation state of the host material 131 to the triplet excitation state of the guest material 132 occurs, just as in the energy transfer from the singlet excitation state of the host material 131 to the singlet excitation state of the guest material 132.

[0087] In the light-emitting element of an embodiment of the present invention, in which the guest material 132 is a fluorescent material, the efficiency of energy transfer to the triplet excitation state of the guest material 132 is preferably low. That is, the energy transfer efficiency based on the Dexter mechanism from the host material 131 to the guest material 132 is preferably low, and the energy transfer efficiency based on the Förster mechanism from the host material 131 to the guest material 132 is preferably high.

[0088] As described above, the energy transfer efficiency of the Förster mechanism does not depend on the excitation lifetime τ of the host material 131. In contrast, the energy transfer efficiency of the Dexter mechanism does depend on the excitation lifetime τ of the host material 131. Therefore, the excitation lifetime τ of the host material 131 is preferably short to reduce the energy transfer efficiency of the Dexter mechanism.

[0089] In a similar way to the energy transfer from the host material 131 to the guest material 132, the energy transfer also occurs through both the Förster mechanism and the Dexter mechanism in the energy transfer process from the exciplex to the guest material 132.

[0090] Accordingly, one embodiment of the present invention provides a light-emitting element containing organic compound 131_1 and organic compound 131_2 as host material 131, which combine to form an exciplex that acts as an energy donor capable of efficiently transferring energy to the host material 132. The exciplex formed by organic compound 131_1 and organic compound 131_2 has a singlet excitation energy level and a triplet excitation energy level adjacent to each other; consequently, a transition from a triplet exciton generated in the light-emitting layer 130 to a singlet exciton (reverse intersystem crossing) is likely to occur. This can increase the efficiency of singlet exciton generation in the light-emitting layer 130.To promote energy transfer from the singlet excitation state of the exciplex to the singlet excitation state of the guest material 132, which serves as an energy acceptor, the emission spectrum of the exciplex preferably overlaps with the absorption band of the guest material 132, which is located on the longest wavelength side (lowest energy side). Consequently, the efficiency of generating the singlet excitation state of the guest material 132 can be increased.

[0091] Furthermore, the fluorescence lifetime of a thermally activated, delayed fluorescent component under light emitted by the exciplex is preferably short, particularly preferably 10 ns or longer and 50 µs or shorter, more preferably 10 ns or longer and 30 µs or shorter.

[0092] The proportion of a thermally activated, delayed-release fluorescent component among the light emitted by the exciplex is preferably high. In particular, the proportion of a thermally activated, delayed-release fluorescent component among the light emitted by the exciplex is preferably higher than or equal to 5%, more preferably higher than or equal to 10%. <material>

[0093] Next, the components of a light-emitting element of an embodiment of the present invention will be described in detail. <<Licht emittierende Schicht> >

[0094] The following describes materials that can be used for the light-emitting layer 130.

[0095] In the light-emitting layer 130, the host material 131 is present in the highest weight fraction, and the guest material 132 (the fluorescent material) is dispersed in the host material 131. The S1 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 S1 level of the guest material 132 (the fluorescent material) in the light-emitting layer 130. 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 132 (the fluorescent material) in the light-emitting layer 130.

[0096] The organic compound 131_1 preferably has a function for converting the triplet excitation energy to the singlet excitation energy spontaneously by reverse intersystem crossing and preferably has a function for emitting thermally activated delayed fluorescence at room temperature. As an example of the material capable of converting the triplet excitation energy to the singlet excitation energy, a thermally activated delayed fluorescent material can be specified. In the case where the thermally activated delayed fluorescent material consists of a single material type, any of the following materials can be used, for example.

[0097] Firstly, a fullerene, a derivative thereof, or an acridine derivative, such as proflavin, eosin, and the like, can be mentioned. Further examples include a metal-containing porphyrin, 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 (PtCl2OEP).

[0098] A heterocyclic compound comprising a π-electron-rich heteroaromatic framework and a π-electron-poor heteroaromatic framework can also be used as a thermally activated, delayed fluorescent material consisting of one material type. 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-dihydroacridin)phenyl]sulfone (abbreviation: DMAC-DPS) or 10-Phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA) are used.The heterocyclic compound is preferred because it possesses both the π-electron-rich and the π-electron-poor heteroaromatic frameworks; therefore, its electron transport and hole transport properties are high. Among the π-electron-poor heteroaromatic frameworks, 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 the π-electron-rich heteroaromatic frameworks, an acridine framework, a phenoxazine framework, a phenothiazine framework, a furan framework, a thiophene framework, and a pyrrole framework exhibit high stability and reliability; consequently, one or more of these frameworks is / are preferably included. An indole or carbazole skeleton, in particular a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton, is preferable as a pyrrole skeleton.It should be noted that a substance in which the π-electron-rich heteroaromatic framework is directly bonded to the π-electron-poor heteroaromatic framework is particularly preferred, since both the donor property of the π-electron-rich heteroaromatic framework and the acceptor property of the π-electron-poor heteroaromatic framework are increased, and the difference between the singlet excitation energy level and the triplet excitation energy level becomes small.

[0099] It should be noted that organic compound 131_1 need not have a function for emitting thermally activated delayed fluorescence, as long as it has a function for converting the triplet excitation energy to the singlet excitation energy by reverse intersystem crossing. In this case, organic compound 131_1 preferably has a structure in which the π-electron-deficient heteroaromatic framework and the π-electron-rich heteroaromatic framework and / or the aromatic amine framework are linked to one another via a structure comprising an m-phenylene group and / or an o-phenylene group, or via an arylene group comprising an m-phenylene group and / or an o-phenylene group. Preferably, the arylene group is a biphenylene group. This can increase the T1 level of organic compound 131_1.In this case, it is also preferred that the π-electron-deficient heteroaromatic framework comprises a diazine framework (a pyrimidine framework, a pyrazine framework, or a pyridazine framework) or a triazine framework. Furthermore, the π-electron-rich heteroaromatic framework preferably comprises one or more of the following frameworks: an acridine framework, a phenoxazine framework, a phenothiazine framework, a furan framework, a thiophene framework, and a pyrrole framework. A dibenzofuran framework is preferred as the furan framework. A dibenzothiophene framework is preferred as the thiophene framework. An indole framework or a carbazole framework, in particular a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole framework, is preferred as the pyrrole framework. As an aromatic amine framework, a tertiary amine that does not include an NH bond, in particular a triarylamine framework, is preferable.As an aryl group of a triarylamine framework, a substituted or unsubstituted aryl group with 6 to 13 carbon atoms contained in a ring is preferred, and examples of the aryl group include a phenyl group, a naphthyl group and a fluorenyl group.

[0100] As examples of the aromatic amine framework and the π-electron-rich heteroaromatic framework described above, frameworks represented by the following general formulas (101) to (117) are given. It should be noted that X in the general formulas (113) to (116) represents an oxygen atom or a sulfur atom.

[0101] Furthermore, as examples of the π-electron-deficient heteroaromatic framework described above, frameworks are given which are represented by the following general formulas (201) to (218).

[0102] In the case where a framework with hole-transport property (e.g., the π-electron-rich heteroaromatic framework and / or the aromatic amine framework) and a framework with electron-transport property (e.g., the π-electron-poor heteroaromatic framework) are bonded to each other via a bonding group comprising an m-phenylene group and / or an o-phenylene group, or via a bonding group comprising an arylene group comprising the m-phenylene group and / or the o-phenylene group, examples of the bonding group include frameworks represented by the following general formulas (301) to (314). Examples of the arylene group described above include a phenylene group, a biphenyldiyl group, a naphthalenediyl group, a fluorenediyl group, and a phenanthrenediyl group.

[0103] The aromatic amine framework (e.g. the triarylamine framework), the π-electron-rich heteroaromatic framework (e.g. a ring comprising the acridine framework, the phenoxazine framework, the phenothiazine framework, the furan framework, the thiophene framework or the pyrrole framework), and the π-electron-poor heteroaromatic framework (e.g. a ring comprising the diazine framework or the triazine framework) described above, or the general formulas (101) to (117), general formulas (201) to (218) and general formulas (301) to (314) described above, may each contain a substituent. A 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 12 carbon atoms.Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl, and the like. Specific examples of cycloalkyl groups with 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. Specific examples of aryl groups with 6 to 12 carbon atoms include phenyl, naphthyl, biphenyl, and the like. The aforementioned substituents may be bonded together to form a ring. In the case where, for example, a carbon atom at the 9 position in a fluorene framework has two phenyl groups as substituents, the phenyl groups are bonded to each other to form a spirofluorene framework.It should be noted that an unsubstituted group is advantageous in that it can be easily synthesized and is an inexpensive raw material.

[0104] Furthermore, Ar represents an arylene group with 6 to 13 carbon atoms. The arylene group can contain one or more substituents, and the substituents can be bonded together to form a ring. For example, a carbon atom at the 9-position in a fluorenyl group has two phenyl groups as substituents, and the phenyl groups are bonded together to form a spirofluorene framework. Specific examples of the 6- to 13-carbon arylene group include a phenylene group, a naphthylene group, a biphenylene group, a fluorenediyl group, and the like. In the case where the arylene group has one 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 an aryl group with 6 to 12 carbon atoms.Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl, and the like. Specific examples of cycloalkyl groups with 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. Specific examples of aryl groups with 6 to 12 carbon atoms include phenyl, naphthyl, biphenyl, and the like.

[0105] For example, the arylene group represented by the following structural formulas (Ar-1) to (Ar-18) can be used. It should be noted that the group that can be used as Ar is not limited to these.

[0106] Furthermore, R 1 and R 2 Each of these is independently defined as hydrogen, 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 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, an n-hexyl group, and the like. Specific examples of a cycloalkyl group with 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like. Specific examples of the aryl group with 6 to 13 carbon atoms are a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and the like.The preceding aryl or phenyl group can comprise one or more substituents, and the substituents may be bonded to each other to form a ring. The substituent can also be 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 12 carbon atoms. Specific examples of alkyl groups with 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl, and the like. Specific examples of cycloalkyl groups with 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like.Specific examples of the aryl group with 6 to 12 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, and the like.

[0107] For example, groups represented by the following structural formulas (R-1) to (R-29) can be used as alkyl or aryl groups, represented by R 1 and R 2 is represented. It should be noted that the group which can be used as an alkyl group or aryl group is not limited to this.

[0108] As a substituent, which appears in general formulas (101) to (117), general formulas (201) to (218), general formulas (301) to (314), Ar, R 1 and R 2 The group that can be used is, for example, the alkyl group or the aryl group represented by the structural formulas (R-1) to (R-24) above. It should be noted that the group that can be used as an alkyl or aryl group is not limited to these.

[0109] In the light-emitting layer 130, the guest material 132 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 any of the following materials may be used, for example.

[0110] 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,N'-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,ρ]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-phenylenediame in (abbreviation: 2DPAPPhA), 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)propanedinitrile (abbreviation: DCM1), 2-{2-Methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-Tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-Diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-Isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl )ethenyl]-4H-pyran-4-ylidene}propanenitrile (abbreviation: DCJTB), 2-(2,6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanenitrile (abbreviation: BisDCM), 2-{2,6-Bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin -9-yl)ethenyl]-4H-pyran-4-ylidene}propanenitrile (abbreviation: BisDCJTM) and 5,10,15,20-Tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene.,

[0111] As described above, the energy transfer efficiency based on the Dexter mechanism from the host material 131 (or the Exciplex) to the guest material 132 is preferably low. The rate constant of the Dexter mechanism is inversely proportional to the exponential function of the distance between the two molecules. Therefore, when the distance between the two molecules is approximately 1 nm or less, the Dexter mechanism is dominant, and when the distance is approximately 1 nm or more, the Förster mechanism is dominant. To reduce the energy transfer efficiency of the Dexter mechanism, the distance between the host material 131 and the guest material 132 is preferably large, in particular 0.7 nm or more, more preferably 0.9 nm or more, and even more preferably 1 nm or more. In light of the above, the guest material 132 preferably has a substituent that prevents it from approaching the host material 131.The substituent is preferably an aliphatic hydrocarbon, more preferably an alkyl group, and even more preferably a branched alkyl group. In particular, the guest material 132 preferably comprises at least two alkyl groups, each having two or more carbon atoms. Alternatively, the guest material 132 preferably comprises at least two branched alkyl groups, each having three to ten carbon atoms. Alternatively, the guest material 132 preferably comprises at least two cycloalkyl groups, each having three to ten carbon atoms.

[0112] Organic compound 131_2 is a substance that can form an exciplex together with organic compound 131_1. In particular, a zinc- or aluminum-based metal complex, an oxadiazole derivative, a triazole derivative, a benzimidazole derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a dibenzothiophene derivative, a dibenzofuran derivative, a pyrimidine derivative, a triazine derivative, a pyridine derivative, a bipyridine derivative, a phenanthroline derivative, or the like may be used. Further examples include an aromatic amine and a carbazole derivative.Preferably, in this case, the organic compound 131_1, the organic compound 131_2, and the guest material 132 (the fluorescent material) are selected such that the emission peak of the exciplex formed by the organic compound 131_1 and the organic compound 131_2 overlaps with an absorption band on the longest wavelength side (low energy side) of the guest material 132 (the fluorescent material). This allows a light-emitting element with drastically improved emission efficiency to be provided.

[0113] Alternatively, any of the following hole transport materials and electron transport materials can be used as organic compound 131_2.

[0114] 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.

[0115] Examples of 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.

[0116] 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.

[0117] 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-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 1,4-Bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene and the like.

[0118] 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 material with a density of / Vs or higher and having 14 to 42 carbon atoms is particularly preferred.

[0119] 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.

[0120] 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).

[0121] 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). The substances described here are mainly substances with a hole mobility of 1 × 10⁻⁶. -6 cm 2 / Vs or higher. It should be noted that, apart from these substances, any substance can be used that has the property of transporting more holes than electrons.

[0122] A material that has the property of transporting more electrons than holes can be used as an electron transport material, with a material having an electron mobility of 1 × 10 -6 cm 2 / Vs or higher is preferable. A π-electron-deficient heteroaromatic compound, such as a nitrogen-containing heteroaromatic compound, a metal complex, or the like, can be used as a material that readily accepts electrons (as a material with electron transport properties). Specific examples include a metal complex with a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand, an oxadiazole derivative, a triazole derivative, a phenanthroline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, and the like.

[0123] Examples include metal complexes with a quinoline or benzoquinoline skeleton, such as 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), and the like. A metal complex with an oxazole-based or thiazole-based ligand, such as... B. Bis[2-(2-benzoxazolyl)phenolate]zinc(II) (abbreviation: ZnPBO) or bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), can be used as alternatives. Besides such metal complexes, any of the following compounds can be used: heterocyclic compounds, such as...2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(biphenyl-4-yl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 9-[4-(4,5-Diphenyl-4H-1,2,4-triazol-3-yl)phenyl]-9H-carbazole (abbreviation: CzTAZ1), 2,2',2"-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP) and 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen); heterocyclic compounds with a diazine backbone, such as...2-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-Carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-Diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[fh]quinoxaline (abbreviation: 7mDBTPDBq-II) 6-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-[3-(3,9'-bi-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzCzPDBq), 4,6-Bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-Bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II) and 4,6-Bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm); heterocyclic compounds with a triazine skeleton, such as... B. PCCzPTzn; heterocyclic compounds with a pyridine skeleton, such as e.g.3,5-Bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy); and heteroaromatic compounds, such as 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs). Among the heterocyclic compounds, those with diazine frameworks (pyrimidine, pyrazine, pyridazine) or a pyridine framework are very reliable and stable and are therefore preferred. Furthermore, these heterocyclic compounds exhibit high electron transport properties, which contributes to a reduction in the drive voltage. A high-molecular-weight compound, such as... B. Poly(2,5-pyridindiyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py) or poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy), can be used as a further alternative. The substances described here are mainly substances with an electron mobility of 1 × 10⁻⁶. -6 cm 2 / Vs or higher. It should be noted that other substances can also be used, as long as their electron transport properties are higher than their hole transport properties.

[0124] 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 arranging 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 the host material, and the second light-emitting layer is formed using a substance with electron-transport properties as the host material.

[0125] The light-emitting layer 130 can contain a different material than the host material 131 and the guest material 132. < <lochinjektionsschicht>>

[0126] 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 it 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.

[0127] A hole injection layer 111 can also be a layer containing a composite material of a hole transport material and a material that accepts electrons from the hole transport material. Alternatively, a layer arrangement can be used consisting of a layer containing a material with electron-accepting properties and a layer containing a hole transport material. In a stable state or in the presence of an electric field, electrical charges can be transferred between these materials. Examples of materials with 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) can be used. Alternatively, a transition metal oxide, such as an oxide of a metal from Group 4 to Group 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.

[0128] 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 of the aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, and the like, which have been described as examples of hole transport material that can be used in the light-emitting layer 130, can be used. Furthermore, the hole transport material can be a high-molecular-weight compound. < <lochtransportschicht>>

[0129] 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, 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.

[0130] 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, apart from the substances mentioned above, any substance can 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 can be stacked on top of each other. < <elektronentransportschicht>>

[0131] 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) through 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 (as a material with electron transport properties). In particular, a metal complex with a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand that has been described as an electron transport material suitable for use in the light-emitting layer 130 can be specified. Furthermore, an oxadiazole derivative, a triazole derivative, a phenanthroline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, and the like can be specified. A substance with an electron mobility of 1 × 10 -6 cm 2 / Vs or higher is preferable. It should be noted that, apart from these substances, any substance possessing the property of transporting more electrons than holes can be used for the electron transport layer. The electron transport layer 118 is not limited to a single layer and can comprise two or more superimposed layers containing the aforementioned substances.

[0132] A layer controlling electron carrier transport can be provided between the electron transport layer 118 and the light-emitting layer 130. This layer is formed by adding a small amount of a substance with high electron-capturing properties to a previously described material with high electron transport properties. The layer is capable of adjusting the charge carrier balance by suppressing electron carrier transport. Such a structure is very effective in preventing problems (such as a reduction in the element's lifetime) that arise when electrons pass through the light-emitting layer. < <elektroneninjektionsschicht>>

[0133] 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 any 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 electron-donating property can be a metal of group 1, a metal of group 2, an oxide of any 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 ). A rare-earth metal compound, such as erbium fluoride (ErF3), can be used as an alternative. An electride can also be used for the electron injection layer 119. Examples of the electride include a substance 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 substance that can be used for the electron transport layer 118.

[0134] 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 is characterized by 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.

[0135] 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.

[0136] The quantum dot can be, for example, a colloidal quantum dot, an alloy 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> >

[0137] 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.

[0138] Either electrode 101 or 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 (where L represents 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; therefore, it is possible to reduce the cost of manufacturing a light-emitting element using aluminum.Alternatively, an alloy of silver (Ag) and nitrogen (N) (where N represents one or more of yttrium (Y), Nd, magnesium (Mg), ytterbium (Yb), aluminum (Al), titanium (Ti), gallium (Ga), zinc (Zn), indium (In), tungsten (W), manganese (Mn), tin (Sn), iron (Fe), nickel (Ni), copper (Cu), palladium (Pd), iridium (Ir), or 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.

[0139] Light emitted by the light-emitting layer is extracted by 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 can be one whose visible light transmittance 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.

[0140] 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-containing indium tin oxide (ITSO), indium zinc oxide, titanium-containing indium oxide-tin oxide, indium titanium oxide, or tungsten- and zinc-containing indium oxide may be used. A thin metal film of 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 silver (Ag), an alloy of Ag and aluminum (Al), an alloy of Ag and magnesium (Mg), an alloy of Ag and gold (Au), an alloy of Ag and ytterbium (Yb), or the like.

[0141] 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, an inorganic, carbon-based 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.

[0142] Alternatively, electrode 101 and / or electrode 102 can be formed by arranging two or more of these materials on top of each other.

[0143] Furthermore, to improve light extraction efficiency, a material with a higher refractive index than the transmitting electrode can be formed in contact with it. Such a material can be conductive or non-conductive, as long as it transmits visible light. In addition to the oxide conductor described above, examples include oxide semiconductors and organic materials. Examples of organic materials include those used in the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer. Alternatively, an inorganic, carbon-based material or a thin metal film that allows light transmission can be used.A large number of layers, each formed using the material with a high refractive index and having a thickness of several nanometers to several tens of nanometers, can be arranged on top of each other.

[0144] 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.

[0145] In the case where electrode 101 or electrode 102 is used as the anode, a material with a high work function (higher than or equal to 4.0 eV) is preferably used.

[0146] Alternatively, electrodes 101 and 102 can each be a layered arrangement of a conductive material with a function for reflecting light and a conductive material with a function for transmitting light. In this case, electrodes 101 and 102 can each have a function for adjusting the optical path length, so that light of a desired wavelength emitted by each light-emitting layer oscillates and is amplified; thus, such a structure is preferable.

[0147] 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>>

[0148] 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.

[0149] 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 may be used, for example. Alternatively, a flexible substrate may 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 vapor deposition, or the like may be used. Another material may be used, provided that the substrate serves as a support in a manufacturing process of the light-emitting element or an optical element, or provided that it has a function of protecting the light-emitting element or an optical element.

[0150] For example, in this description and similar examples, a light-emitting element can be formed using various substrates. There is no particular restriction regarding the type of substrate. 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, a 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 plastic substrates, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Another example is a resin, such as acrylic. Polypropylene, polyester, polyvinyl fluoride, and polyvinyl chloride can also be cited as examples. Further examples include polyamide, polyimide, aramid, epoxy, vapor-deposited inorganic films, paper, and the like.

[0151] Alternatively, a flexible substrate can be used, with the light-emitting element positioned 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 also be transferred to a substrate with low heat resistance or to a flexible substrate. For the separating layer described above, for example, a layer arrangement comprising inorganic films, namely a tungsten film and a silicon oxide film, and a structure in which a resin film of polyimide or the like is formed over a substrate can be used.

[0152] 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 can be transferred include, in addition to those mentioned above, a cellophane substrate, a rock substrate, a wood substrate, a fabric substrate (including natural fibers (e.g., silk, cotton, and hemp), synthetic fibers (e.g., nylon, polyurethane, and polyester), regenerated fibers (e.g., acetate, cupro, viscose, and 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.

[0153] The light-emitting element can, for example, be formed over an electrode electrically connected to a field-effect transistor (FET) formed over any of the substrates described above. Accordingly, an active-matrix display device can be manufactured in which the FET controls the operation of the light-emitting element 150.

[0154] In embodiment 1, one embodiment of the present invention has been described. Further embodiments of the present invention are described in embodiments 2 to 10. It should be noted that an embodiment of the present invention is not limited to these. 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 embodiment 1 and embodiments 2 to 10. The example described involves the use of an embodiment of the present invention with a light-emitting element; however, 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.Although another example, in which the EL layer contains the host material and the guest material having a function for emitting fluorescence, or the guest material having a function for converting triplet excitation energy into light emission, and the host material contains a first organic compound in which the difference between the singlet excitation energy level and the triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV, is shown as an embodiment of the present invention, this embodiment is not limited to such an embodiment. Depending on the circumstances or conditions, the host material of an embodiment of the present invention need not necessarily contain the first organic compound in which the difference between the singlet excitation energy level and the triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV.Alternatively, in the first organic compound, the difference between the singlet excitation energy level and the triplet excitation energy level need not necessarily be greater than 0 eV and less than or equal to 0.2 eV. Although another example in which a first organic compound and a second organic compound form an exciplex is shown as an embodiment of the present invention, an embodiment of the present invention is not limited to this. Depending on the circumstances or conditions, for example, the first organic compound and the second organic compound of an embodiment of the present invention need not necessarily form an exciplex.Although another example, in which the HOMO level of one of the first organic compounds and the second organic compound is higher than or equal to the HOMO level of the other, and the LUMO level of one of the first organic compounds and the second organic compound is higher than or equal to the LUMO level of the other, is shown as an embodiment of the present invention, an embodiment of the present invention is not limited thereto. Depending on the circumstances or conditions, an embodiment of the present invention need not necessarily have a structure in which the HOMO level of one of the first organic compounds and the second organic compound is higher than or equal to the HOMO level of the other, and the LUMO level of one of the first organic compounds and the second organic compound is higher than or equal to the LUMO level of the other.

[0155] The structure described above for this embodiment can be used in a suitable combination with any of the other embodiments. (Version 2)

[0156] In this embodiment, a light-emitting element with a structure that differs from that described in embodiment 1, as well as light emission mechanisms of the light-emitting element, are described below based on Fig. 4A to Fig. 4C described. In Fig. In some cases, section 4A will have 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, common reference symbols are used for sections with similar functions, and a detailed description of the sections is omitted in some cases. <Strukturbeispiel des Licht emittierenden Elements>

[0157] Fig. Figure 4A is a schematic cross-sectional view of a light-emitting element 152 of an embodiment of the present invention.

[0158] The light-emitting element 152 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 140.

[0159] It should be noted that in the following description of the light-emitting element 152, electrode 101 serves as the anode and electrode 102 as the cathode; however, the functions of the light-emitting element 152 can be interchanged.

[0160] Fig. Figure 4B is a schematic cross-sectional view showing an example of the light-emitting layer 140 in Fig. 4A represents the light-emitting layer 140 in Fig. 4B contains a host material 141 and a guest material 142. The host material 141 contains an organic compound 141_1 and an organic compound 141_2.

[0161] The guest material 142 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 is described below in which a phosphorescent material is used as the guest material 142. The guest material 142 can also be referred to as the phosphorescent material. <Lichtemissionsmechanismus des Licht emittierenden Elements>

[0162] The light emission mechanism of the light-emitting layer 140 is described below.

[0163] The organic compound 141_1 and the organic compound 141_2, which are contained in the host material 141 in the light-emitting layer 140, form an exciplex.

[0164] The combination of organic compound 141_1 and organic compound 141_2 is acceptable as long as it can form an exciplex; however, preferably one of them is a compound with hole transport properties and the other is a compound with electron transport properties. In this case, a donor-acceptor exciplex is readily formed; thus, an exciplex can be formed efficiently.

[0165] The combination of organic compound 141_1 and organic compound 141_2 preferably fulfills the following: The HOMO level of one of organic compound 141_1 and organic compound 141_2 is higher than or equal to the HOMO level of the other organic compound; and the LUMO level of one of the organic compounds is higher than or equal to the LUMO level of the other organic compound.

[0166] How the organic compounds 131_1 and 131_2 appear in the energy band diagrams in Fig. 2A and Fig. 2B, which are described in embodiment 1, is, for example, when the organic compound 141_1 has a hole transport property and the organic compound 141_2 has an electron transport property, the HOMO level of the organic compound 141_1 is preferably higher than or equal to the HOMO level of the organic compound 141_2, and the LUMO level of the organic compound 141_1 is preferably higher than or equal to the LUMO level of the organic compound 141_2. Alternatively, if the organic compound 141_2 has a hole transport property and the organic compound 141_1 has an electron transport property, the HOMO level of the organic compound 141_2 is preferably higher than or equal to the HOMO level of the organic compound 141_1, and the LUMO level of the organic compound 141_2 is preferably higher than or equal to the LUMO level of the organic compound 141_1.In this case, an exciplex formed by organic compound 141_1 and organic compound 141_2 has an excitation energy that essentially corresponds to an energy difference between the HOMO level of one of the organic compounds and the LUMO level of the other organic compound. Furthermore, the difference between the HOMO level of organic compound 141_1 and the HOMO level of organic compound 141_2, as well as the difference between the LUMO level of organic compound 141_1 and the LUMO level of organic compound 141_2, are each preferably 0.2 eV or more, more preferably 0.3 eV or more.

[0167] According to the relationship between the HOMO level and the LUMO level described above, the combination of organic compound 141_1 and organic compound 141_2 preferably fulfills the following: The oxidation potential of one of the organic compounds 141_1 and organic compound 141_2 is higher than or equal to the oxidation potential of the other organic compound; and the reduction potential of one of the organic compounds is higher than or equal to the reduction potential of the other organic compound.

[0168] This means that if organic compound 141_1 has a hole-transport property and organic compound 141_2 has an electron-transport property, the oxidation potential of organic compound 141_1 is preferably lower than or equal to the oxidation potential of organic compound 141_2, and the reduction potential of organic compound 141_1 is preferably lower than or equal to the reduction potential of organic compound 141_2. Alternatively, if organic compound 141_2 has a hole-transport property and organic compound 141_1 has an electron-transport property, the oxidation potential of organic compound 141_2 is preferably lower than or equal to the oxidation potential of organic compound 141_1, and the reduction potential of organic compound 141_2 is preferably lower than or equal to the reduction potential of organic compound 141_1.

[0169] In the case where the combination of organic compounds 141_1 and 141_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 by adjusting 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.

[0170] Organic compound 141_1 is preferably a thermally activated, delayed-release fluorescent emitter. Alternatively, organic compound 141_1 preferably has a function for emitting thermally activated delayed-release fluorescence at room temperature. That is, organic compound 141_1 is a material that can spontaneously generate a singlet excitation state from a triplet excitation state by reverse intersystem crossing. Therefore, the difference between the singlet excitation energy level and the triplet excitation energy level is preferably greater than 0 eV and less than or equal to 0.2 eV. It should be noted that organic compound 141_1 is not necessarily a thermally activated, delayed-release fluorescent emitter, as long as it has a function for converting triplet excitation energy to singlet excitation energy.

[0171] Furthermore, the organic compound 141_1 preferably comprises a framework with hole transport properties and a framework with electron transport properties. The organic compound 141_1 also preferably comprises a π-electron-rich heteroaromatic framework and / or an aromatic amine framework, as well as a π-electron-poor heteroaromatic framework. Moreover, the π-electron-rich heteroaromatic framework is particularly preferably directly bonded to the π-electron-poor heteroaromatic framework, in which case both the donor properties of the π-electron-rich heteroaromatic framework and the acceptor properties of the π-electron-poor heteroaromatic framework are improved, and the difference between the singlet excitation energy level and the triplet excitation energy level becomes small.If organic compound 141_1 has strong donor and acceptor properties, a donor-acceptor exciplex is readily formed by organic compound 141_1 and organic compound 141_2.

[0172] Furthermore, the overlap between a region containing the HOMO and a region containing the LUMO in organic compound 141_1 is preferably small.

[0173] The exciplex formed by organic compounds 141_1 and 141_2 has the HOMO in one of the organic compounds and the LUMO in the other; therefore, the overlap between the HOMO and the LUMO is very small. This means that the exciplex has a small difference between the singlet and triplet excitation energy levels. Therefore, the difference between the triplet and singlet excitation energy levels of the exciplex formed by organic compounds 141_1 and 141_2 is preferably greater than 0 eV and less than or equal to 0.2 eV.

[0174] Fig. 4C shows a correlation between the energy levels of organic compound 141_1, organic compound 141_2, and guest material 142 in the light-emitting layer 140. The following explains what terms and symbols in Fig. Represent 4C: Host (141_1): a host material (the organic compound 141_1); Host (141_2): a host material (the organic compound 141_2); Guest (142): the guest material 142 (the phosphorescent material); S PH1 . the S1 level of the host material (of the organic compound 141_1); T PH1 : the T1 level of the host material (of the organic compound 141_1); S PH2 : the S1 level of the host material (of the organic compound 141_2); T PH2 : the T1 level of the host material (of the organic compound 141_2); T PG : the T1 level of the guest material 142 (the phosphorescent material); S PE : the S1 level of the exciplex; and T PE : the T1 level of the exciplex.

[0175] In the light-emitting element of an embodiment of the present invention, an exciplex is formed by the organic compounds 141_1 and 141_2, which are contained in the light-emitting layer 140. The S1 level (S PE ) of the exciplex and the T1 level (T PE The Exciplex's exits are located close together (see Route E7 in [link]). Fig. 4C).

[0176] One of the organic compounds 141_1 and 141_2, which accepts a hole, and the other, which accepts an electron, interact with each other to immediately form an exciplex. Alternatively, one of the organic compounds, which is brought into an excited state, immediately interacts with the other organic compound to form an exciplex. Consequently, most of the excited states formed in the light-emitting layer 140 exist as exciplexes. The excited state of the host material 141 (the exciplex) can be formed with a lower excitation energy because the excitation energy levels (S1, S2, S3, S4, S5, S6, S7, S8, S9, S1 ... PE and T PE ) of the exciplex are lower than the S1 levels (S PH1 and S PH2 ) of the organic compounds (organic compounds 141_1 and 141_2) that form the exciplex. Accordingly, the drive voltage of the light-emitting element 152 can be reduced.

[0177] Both energies, S PE and T PE The energy of the exciplex is then transferred to the level of the lowest triplet excitation state of the guest material 142 (the phosphorescent material); thus, light emission is obtained (see routes E8 and E9 in [reference]). Fig. 4C).

[0178] Furthermore, the T1 level (T PE ) of the exciplex preferably higher than the T1 level (T PG ) of the guest material 142. In this way, 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 142 will be transferred.

[0179] If the light-emitting layer 140 has the structure described above, light emission from the guest material 142 (the phosphorescent material) of the light-emitting layer 140 can be obtained efficiently.

[0180] It should be noted that in this description and the like, the processes described above via routes E7, E8, and E8 can be referred to as exciplex triplet energy transfer (ExTET). In other words, in the light-emitting layer 140, excitation energy is transferred from the exciplex to the guest material 142. In this case, the efficiency of the reverse intersystem crossing of T PE to S PE and the luminescence quantum yield of S PE not necessarily high; therefore, materials can be selected from a wide range of options.

[0181] It should be noted that the reactions described above can be represented by general formulas (G1) to (G3). D++A−→(D⋅A)* (D⋅A)*+G→D+A+G* G*→G+hv

[0182] In the general formula (G1), one of the organic compounds 141_1 and 141_2 occupies a hole (D). + ) and the other accepts an electron (A - ) whereby organic compound 141_1 and organic compound 141_2 form an exciplex ((D·A)*). In the general formula (G2), energy is transferred from the exciplex ((D·A)*) to the guest material 142 (G), thereby generating an excited state of the guest material 142 (G*). Subsequently, as represented by the general formula (G3), the guest material 142 emits light (hv) in the excited state.

[0183] It should be noted that, in order to efficiently transfer excitation energy from the Exciplex to the guest material 142, the T1 level (T PE ) of the exciplex preferably lower than or equal to the T1 levels (T PH1 and T PH2 ) of the organic compounds (organic compound 141_1 and organic compound 141_2) that form the exciplex. Thus, it is less likely that quenching of the triplet excitation energy of the exciplex due to the organic compounds will occur, leading to efficient energy transfer to the guest material 142.

[0184] For example, if there is a large difference between the S1 level and the T1 level in at least one of the connections forming an exciplex, the T1 level (T PE The T1 level of the exciplex must be lower than or equal to the T1 level of each compound. Furthermore, the T1 level of the guest material is preferably lower than or equal to the T1 level of the exciplex. Therefore, it is difficult to use a material with a high triplet excitation energy level, i.e., a material that emits light with a high emission energy, e.g., blue light, as guest material 142 if the difference between the S1 level and the T1 level of at least one of the compounds is large.

[0185] However, in the organic compound 141_1 of an embodiment of the present invention, there is a difference between the S1 level (S PH1 ) and the T1 level (T PH1 ) small. Therefore, both the S1 level and the T1 level of the organic compound 141_1 can be increased simultaneously, and the T1 level of the exciplex can be increased. Consequently, an embodiment of the present invention, without limitation to the emission color of the guest material 142, can be used with any light-emitting element that emits various types of light, ranging from light with a high emission energy, such as blue light, to light with a low emission energy, such as red light.

[0186] If organic compound 141_1 comprises a framework with strong donor properties, a hole injected into the light-emitting layer 140 is readily injected into and transported to organic compound 141_1. At this point, organic compound 141_2 preferably comprises an acceptor framework with stronger acceptor properties than an acceptor framework of organic compound 141_1. Consequently, organic compound 141_1 and organic compound 141_2 readily form an exciplex. Alternatively, if organic compound 141_1 comprises a framework with strong acceptor properties, an electron injected into the light-emitting layer 140 is readily injected into and transported to organic compound 141_1.At this stage, organic compound 141_2 preferably comprises a donor scaffold that exhibits stronger donor properties than a donor scaffold of organic compound 141_1. Consequently, organic compound 141_1 and organic compound 141_2 readily form an exciplex.

[0187] It should be noted that if organic compound 141_1 has a function for converting the triplet excitation energy into the singlet excitation energy spontaneously by reverse intersystem crossing, and organic compound 141_1 and organic compound 141_2 do not readily form an exciplex, e.g., if the HOMO level of organic compound 141_1 is higher than that of organic compound 141_2 and the LUMO level of organic compound 141_2 is higher than that of organic compound 141_1, then both the electron and the hole, which are charge carriers that have been injected into the light-emitting layer 140, are readily injected and transported into organic compound 141_1. In this case, the charge carrier balance in the light-emitting layer 140 must be controlled by the hole transport property and the electron transport property of the organic compound 141_1.Therefore, in addition to having a function for converting triplet excitation energy into singlet excitation energy, organic compound 141_1 must itself possess a molecular structure with a suitable charge carrier balance, which makes constructing the molecular structure difficult. In contrast, in one embodiment of the present invention, an electron is injected and transported into one of organic compounds 141_1 and organic compound 141_2, and a hole is injected and transported into the other; thus, the charge carrier balance can be easily controlled by adjusting the mixing ratio, and a light-emitting element with high luminous efficacy can be provided.

[0188] Alternatively, for example, if the HOMO level of organic compound 141_2 is higher than that of organic compound 141_1 and the LUMO level of organic compound 141_1 is higher than that of organic compound 141_2, both the electron and the hole, which are charge carriers injected into the light-emitting layer 140, are readily injected and transported into organic compound 141_2. Thus, the charge carriers readily recombine in organic compound 141_2. In the case where the organic compound 141_2 has no function to convert the triplet excitation energy into the singlet excitation energy by itself through reverse intersystem crossing, there is a large energy difference between the S1 level and the T1 level of the organic compound 141_2, such that there is a large energy difference between the T1 level of the guest material 142 and the S1 level of the organic compound 141_2.Thus, the drive voltage of the light-emitting element is increased by a voltage corresponding to the energy difference. In contrast, in one embodiment of the present invention, organic compound 141_1 and organic compound 141_2 can form an exciplex with an excitation energy lower than the excitation energy level of each of the organic compounds (organic compound 141_1 and organic compound 141_2). Therefore, the drive voltage of the light-emitting element can be reduced, and the light-emitting element can be provided with low power consumption.

[0189] Fig. Figure 4C shows the case in which the S1 level of organic compound 141_2 is higher than that of organic compound 141_1 and the T1 level of organic compound 141_1 is higher than that of organic compound 141_2; however, an embodiment of the present invention is not limited thereto. The S1 level of organic compound 141_1 can be higher than that of organic compound 141_2, and the T1 level of organic compound 141_1 can be higher than that of organic compound 141_2. Alternatively, the S1 level of organic compound 141_1 can be substantially the same as that of organic compound 141_2. Alternatively, the S1 level of organic compound 141_2 can be higher than that of organic compound 141_1, and the T1 level of organic compound 141_2 can be higher than that of organic compound 141_1.It should be noted that in any case the T1 level of the exciplex is preferably lower than or equal to the T1 level of each of the organic compounds (organic compound 141_1 and organic compound 141_2) that form the exciplex.

[0190] Furthermore, the mechanism of the energy transfer process between the molecules of the host material 141 and the guest material 142 can be described using two mechanisms, i.e., the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange interaction), as in embodiment 1. For the Förster mechanism and the Dexter mechanism, reference can be made to embodiment 1. <<Konzept zur Förderung der Energieübertragung> >

[0191] In energy transfer via the Förster mechanism, the energy transfer efficiency ϕ ET The luminescence quantum yield ϕ (the fluorescence quantum yield if it is an energy transfer from a singlet excitation state) is higher. Furthermore, the emission spectrum (the fluorescence spectrum in the case of an energy transfer from a singlet excitation state) of the host material 141 preferably overlaps to a large extent with the absorption spectrum (absorption corresponding to the transition from the singlet ground state to the triplet excitation state) of the guest material 142. It is also preferred that the molar absorption coefficient of the guest material 142 is also high. That is, the emission spectrum of the host material 141 overlaps with the absorption band of the guest material 142, which is located on the longest wavelength side.

[0192] To determine the velocity constant k h*→g To increase energy transfer via the Dexter mechanism, the emission spectrum of the host material 141 (a fluorescence spectrum in the case of energy transfer from a singlet excitation state) preferably overlaps to a large extent with the absorption spectrum of the guest material 142 (absorption corresponding to the transition from a singlet ground state to a triplet excitation state). Therefore, the energy transfer efficiency can be optimized by ensuring that the emission spectrum of the host material 141 overlaps with the absorption band of the guest material 142 located on the longest wavelength side.

[0193] In a similar way to the energy transfer from the host material 141 to the guest material 142, the energy transfer also occurs through both the Förster mechanism and the Dexter mechanism in the energy transfer process from the exciplex to the guest material 142.

[0194] Accordingly, one embodiment of the present invention provides a light-emitting element containing organic compound 141_1 and organic compound 141_2 as host material 141, which combine to form an exciplex that acts as an energy donor capable of efficiently transferring energy to the host material 142. The exciplex formed by organic compound 141_1 and organic compound 141_2 has singlet and triplet excitation energy levels that are close to each other; consequently, the exciplex generated in the light-emitting layer 140 can be formed with an excitation energy that is lower than the excitation energies of organic compound 141_1 and organic compound 141_2. This can reduce the drive voltage of the light-emitting element 142.To promote energy transfer from the singlet excitation state of the exciplex to the triplet excitation state of the guest material 142, which serves as the energy acceptor, the emission spectrum of the exciplex preferably overlaps with the absorption band of the guest material 142, which is located on the longest wavelength side (lowest energy side). Consequently, the efficiency of generating the triplet excitation state of the guest material 142 can be increased. <Material, das bei den Licht emittierenden Schichten verwendet werden kann>

[0195] Next, the following describes materials that can be used in the light-emitting layer 140.

[0196] In the light-emitting layer 140, the host material 141 is present in the highest weight fraction, and the guest material 142 (the phosphorescent material) is dispersed in the host material 141. The T1 level of the host material 141 (organic compound 141_1 and organic compound 141_2) in the light-emitting layer 140 is preferably higher than the T1 level of the guest material (guest material 142) in the light-emitting layer 140.

[0197] The organic compound 141_1 preferably has a function for emitting thermally activated delayed fluorescence at room temperature. This means that the energy difference between a triplet excitation energy level and a singlet excitation energy level is preferably small, in particular 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. A thermally activated delayed fluorescent material can be given as an example of a material in which the energy difference between the triplet excitation energy level and the singlet excitation energy level is small. Any of the materials shown as examples in embodiment 1 can be used as a thermally activated delayed fluorescent material.

[0198] It should be noted that organic compound 141_1 does not necessarily have to exhibit a function for emitting thermally activated delayed fluorescence, as long as the energy difference between the triplet excitation energy level and the singlet excitation energy level is small. In this case, organic compound 141_1 preferably has a structure in which the π-electron-deficient heteroaromatic framework and the π-electron-rich heteroaromatic framework and / or the aromatic amine framework are linked to one another via a structure comprising an m-phenylene group and / or an o-phenylene group, or via an arylene group comprising an m-phenylene group and / or an o-phenylene group. Preferably, the arylene group is a biphenylene group. This can increase the T1 level of organic compound 141_1.In this case, it is also preferred that the π-electron-deficient heteroaromatic framework comprises a diazine framework (a pyrimidine framework, a pyrazine framework, or a pyridazine framework) or a triazine framework. Furthermore, the π-electron-rich heteroaromatic framework preferably comprises one or more of the following frameworks: an acridine framework, a phenoxazine framework, a phenothiazine framework, a furan framework, a thiophene framework, and a pyrrole framework. An indole framework or a carbazole framework, in particular a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole framework, is preferred as the pyrrole framework.

[0199] The organic compound 141_2 is preferably a substance that can form an exciplex together with the organic compound 141_1. In particular, zinc- and aluminum-based metal complexes, heteroaromatic compounds such as an oxadiazole derivative, a triazole derivative, a benzimidazole derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a dibenzothiophene derivative, a dibenzofuran derivative, a pyrimidine derivative, a triazine derivative, a pyridine derivative, a bipyridine derivative, and a phenanthroline derivative, or an aromatic amine, as well as a carbazole derivative, which in embodiment 1 are specified as electron transport material and hole transport material, can be used.Preferably, in this case, the organic compound 141_1, the organic compound 141_2, and the guest material 142 (phosphorescent material) are selected such that the emission peak of the exciplex formed by the organic compound 141_1 and the organic compound 141_2 overlaps with an absorption band, in particular with an absorption band on the longest wavelength side, of a triplet metal-to-ligand charge transfer (MLCT) transition of the guest material 142 (phosphorescent material). This allows a light-emitting element with drastically improved emission efficiency to be provided. It should be noted that if a thermally activated, delayed-release fluorescent material is used instead of the phosphorescent material, the absorption band is preferably a singlet absorption band on the longest wavelength side.

[0200] The guest material 142 (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.

[0201] 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-KN2]phenyl-κC}i iridium(III) (abbreviation: Ir(mpptz-dmp)3), Tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(Mptz)3) Tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(iPrptz-3b)3) 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 asfac-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-fJphenanthridinato]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: FIr6), Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III)picolinate (abbreviation: FIrpic), Bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2' }iridium(III)picolinate (abbreviation: Ir(CF3ppy)2(pic)) and Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]Iridium(III)acetylacetonate (abbreviation: FIr(acac)). Among the materials mentioned above, the organometallic iridium complexes with a 4H-triazole framework exhibit high reliability and high light yield and are therefore particularly preferred.

[0202] Examples of the substance exhibiting an emission peak in the green or yellow wavelength range include organometallic iridium complexes with a pyrimidine framework, 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-r 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)), 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 yield and are therefore particularly preferred.

[0203] Examples of the substance exhibiting an emission peak in the yellow or red wavelength range include organometallic iridium complexes with a pyrimidine backbone, 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 backbone, such as... B. (Acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: Ir(tppr)2(acac)), Bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)) and (Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac)); organometallic iridium complexes with a pyridine 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 yield and are therefore particularly preferred. Furthermore, the organometallic iridium complexes with a pyrazine framework can exhibit red light emission with advantageous chromaticity.

[0204] Any material capable of converting triplet excitation energy into light emission can be used as the light-emitting material in light-emitting layer 140. In addition to a phosphorescent material, a thermally activated, delayed-release fluorescent 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-release fluorescent material" in the description.

[0205] In the case where the material emitting thermally activated delayed fluorescence is formed from a type of material, in particular any of the thermally activated delayed fluorescent materials described in embodiment 1 may be used.

[0206] The light-emitting layer 140 can have a structure in which two or more layers are arranged one above the other. For example, if the light-emitting layer 140 is formed by arranging 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 the host material, and the second light-emitting layer is formed using a substance with electron-transport properties as the host material.

[0207] The light-emitting layer 140 can contain a different material than the host material 141 and the guest material 142.

[0208] It should be noted that the light-emitting layer 140 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 used.

[0209] The structure described in this embodiment can be used in a suitable combination with any of the structures described in the other embodiments. (Version 3)

[0210] In this embodiment, light-emitting elements with structures that differ from those described in embodiments 1 and 2, as well as the light-emission mechanisms of the light-emitting elements, are described below based on: Fig. 5A to Fig. 5C as well Fig. 6A and Fig. 6B described. Fig. 5A to 5C as well as Fig. 6A and Fig. In some cases, 6B 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>

[0211] Fig. 5A is a schematic cross-sectional view of a light-emitting element 250.

[0212] The light-emitting element 250, which is in Fig. 5A, as shown, comprises a variety of light-emitting units (one light-emitting unit 106 and one light-emitting unit 108 in Fig. 5A) between a pair of electrodes (electrode 101 and electrode 102). Any one of the plurality of light-emitting units preferably has the same structure as the EL layer 100, which is described in Fig. 1A is shown. That is: The light-emitting element 150 in Fig. 1A preferably comprises a light-emitting unit, and the light-emitting element 250 preferably comprises a plurality of light-emitting units. It should be noted that in the following description of the light-emitting element 250, electrode 101 serves as the anode and electrode 102 as the cathode; however, the functions of the light-emitting element 250 can be interchanged.

[0213] The light-emitting element 250, which is in Fig. As shown in Figure 5A, 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 different structures. For example, the EL layer 100, which is shown in Figure 5A, is arranged in the following diagram: Fig. 1A is shown, preferably used in the light-emitting unit 108.

[0214] The light-emitting element 250 comprises a light-emitting layer 120 and a light-emitting layer 130. 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 130, a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 119.

[0215] 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.

[0216] 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 substance 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 on the anode side is in contact with the charge-generating layer 115, as in the case of light-emitting unit 108, 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.

[0217] 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 materials 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.

[0218] 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. 5A 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 becomes higher than that of electrode 102.

[0219] 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). In the case where the conductivity of the charge-generating layer 115 is as high as that of the pair of electrodes, charge carriers generated in the charge-generating layer 115 flow towards the film surface, so that in some cases light is emitted in an area where electrodes 101 and 102 do not overlap.To suppress such a defect, the charge-generating layer 115 is preferably formed using a material whose conductivity is lower than that of the pair of electrodes.

[0220] 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.

[0221] The light-emitting element, which comprises two light-emitting units, is defined by Fig. 5A 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 means of a plurality of light-emitting units separated from the charge-generating layer between a pair of electrodes, a light-emitting element can be provided, just as in the light-emitting element 250, 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.

[0222] If the structure of the EL layer 100, which is in Fig. As shown in 1A, a light-emitting element with high luminous efficacy can be provided for at least one of the multitude of units.

[0223] Preferably, the light-emitting layer 130 contained in the light-emitting unit 108 has the structure described in embodiment 1. Thus, the light-emitting element 250 contains a fluorescent material as the light-emitting material and has a high luminous efficacy, which is preferable.

[0224] Furthermore, the light-emitting layer 120, which is contained in the light-emitting unit 106, contains, for example, a host material 121 and a guest material 122, as shown in Fig. Figure 5B is shown. It should be noted that guest material 122 is described below as a fluorescent material. <Lichtemissionsmechanismus der Licht emittierenden Schicht 120>

[0225] The light emission mechanism of the light-emitting layer 120 is described below.

[0226] Excitons are formed when electrons and holes injected into the light-emitting layer 120 from the pair of electrodes (electrode 101 and electrode 102) or the charge-generating layer recombine. 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.

[0227] 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 generated is brought into an excited state.

[0228] 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.

[0229] Since the guest material 122 is a fluorescent material, it emits light immediately upon the formation of a singlet excitation state. To obtain a high light yield 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.

[0230] Next, the case is described in which the recombination of charge carriers forms a triplet excitation state of the host material 121. The correlation between the energy levels of the host material 121 and the guest material 122 in this case is shown in Fig. 5C shown. The following clarifies what terms and symbols in Fig. 5C. 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. 5C 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).

[0231] As in Fig. As shown in 5C, triplet excitons formed by charge carrier recombination lie close together, and excitation energy is transferred, and spin angular momenta are exchanged; as a result, a reaction occurs in which one of the triplet excitons is converted into a singlet exciton having the energy of the S1 level of the host material 121 (S FH ), that is, that a triplet-triplet annihilation (TTA) occurs (see TTA in Fig. 5C). 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. 5C), and a singlet excitation state of the guest material 122 is formed, causing the guest material 122 to emit light.

[0232] 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.

[0233] In the case where a triplet excitation state of the guest material 122 is formed by charge carrier recombination, the triplet excitation state 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 ) will be transferred (see Route E2 in Fig. 5C) and is then used for TTA.

[0234] In other words, the host material 121 preferably has a function for converting triplet excitation energy into singlet excitation energy by inducing TTA, such 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 obtain 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 ).

[0235] It should be noted that, in particular, 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.

[0236] It should be noted that the host material 121 can consist of a single compound or a multitude of compounds.

[0237] It should be noted that in each of the structures described above, the guest materials (fluorescent materials) used in light-emitting unit 106 and light-emitting unit 108 can be the same or different. If the same guest material is 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 different guest materials are used for light-emitting unit 106 and light-emitting unit 108, light-emitting element 250 can exhibit multicolored light emission, which is preferable.Preferably, the guest materials are selected in such a way that a white light emission with high color rendering properties or a light emission of at least red, green and blue can be obtained.

[0238] In the case where the light-emitting units 106 and 108 contain different guest materials, light emitted by the light-emitting layer 120 preferably exhibits a peak on the shorter wavelength side than light emitted by the light-emitting layer 130. Since the luminance of a light-emitting element using a material with a high triplet excitation state 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>

[0239] Fig. 6A is a schematic cross-sectional view of a light-emitting element 252.

[0240] The light-emitting element 252, which is in Fig. Figure 6A, like the light-emitting element 250 described above, comprises a plurality of light-emitting units (one light-emitting unit 106 and one light-emitting unit 110 in Fig. 6A) between a pair of electrodes (electrode 101 and electrode 102). A light-emitting unit preferably has the same structure as the EL layer 100, which is described in Fig. Figure 4A is shown. It should be noted that the light-emitting unit 106 and the light-emitting unit 110 may have the same structure or different structures.

[0241] The light-emitting element 252, which is in Fig. As shown in Figure 6A, the light-emitting unit 106 and the light-emitting unit 110 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 110. For example, the EL layer 100, which is shown in Figure 6A, is preferably arranged as a charge-generating layer 115. Fig. 4A is shown, where the light-emitting unit 110 is used.

[0242] The light-emitting element 252 comprises the light-emitting layer 120 and a light-emitting layer 140. The light-emitting unit 106 comprises, in addition to the light-emitting layer 120, the hole injection layer 111, the hole transport layer 112, the electron transport layer 113, and the electron injection layer 114. The light-emitting unit 110 comprises, in addition to the light-emitting layer 140, the hole injection layer 116, the hole transport layer 117, the electron transport layer 118, and the electron injection layer 119.

[0243] Furthermore, the light-emitting layer of the light-emitting unit 110 preferably contains a phosphorescent material. That is to say, the light-emitting layer 120 contained in the light-emitting unit 106 preferably has the structure described in structural example 1 of embodiment 3, and the light-emitting layer 140 contained in the light-emitting unit 110 has the structure described in embodiment 2.

[0244] It should be noted that light emitted by light-emitting layer 120 preferably exhibits a peak on the shorter wavelength side than light emitted by light-emitting layer 140. Since the luminance of a light-emitting element using a phosphorescent material emitting short-wavelength light tends to degrade rapidly, a short-wavelength fluorescence is used so that a light-emitting element with less luminance degradation can be provided.

[0245] Furthermore, the light-emitting layer 120 and the light-emitting layer 140 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.

[0246] The above structure is also suitable for obtaining white light emission. If light-emitting layer 120 and light-emitting layer 140 emit light in complementary colors, white light emission can be obtained.

[0247] Furthermore, a white light emission with high color rendering properties, composed of three primary colors or four or more colors, can be obtained by using a variety of light-emitting substances emitting light at different wavelengths for one or both of the light-emitting layers 120 and 140. In this case, one or both of the light-emitting layers 120 and 140 can be divided into layers, and each of the divided layers can contain a light-emitting material that differs from that of the others. <Strukturbeispiel 3 des Licht emittierenden Elements>

[0248] Fig. Figure 6B is a schematic cross-sectional view of a light-emitting element 254.

[0249] The light-emitting element 254, which is in Fig. Figure 6B, like the light-emitting element 250 described above, comprises a plurality of light-emitting units (one light-emitting unit 109 and one light-emitting unit 110 in Fig. 6B) between a pair of electrodes (electrode 101 and electrode 102). At least one of the plurality of light-emitting units preferably has the same structure as the EL layer 100 described in Fig. 1A is shown, and the other light-emitting unit preferably has the same structure as the EL layer 100 shown in Fig. 4A is shown.

[0250] The light-emitting element 254, which is in Fig. As shown in Figure 6B, the light-emitting unit 109 and the light-emitting unit 110 are arranged one above the other, and a charge-generating layer 115 is provided between the light-emitting unit 109 and the light-emitting unit 110. For example, preferably the same structure as the EL layer 100 shown in Figure 6B is used. Fig. 1A is shown, in which the light-emitting unit 109 is used and has the same structure as the EL layer 100, which is shown in Fig. 4A is preferably used in the light-emitting unit 110.

[0251] The light-emitting element 254 comprises the light-emitting layer 130 and a light-emitting layer 140. The light-emitting unit 109 comprises, in addition to the light-emitting layer 130, the hole injection layer 111, the hole transport layer 112, the electron transport layer 113, and the electron injection layer 114. The light-emitting unit 110 comprises, in addition to the light-emitting layer 140, the hole injection layer 116, the hole transport layer 117, the electron transport layer 118, and the electron injection layer 119.

[0252] This means that the light-emitting layer 130 contained in the light-emitting unit 109 preferably has the structure described in embodiment 1, and the light-emitting layer 140 contained in the light-emitting unit 110 preferably has the structure described in embodiment 2.

[0253] It should be noted that light emitted by light-emitting layer 130 preferably exhibits a peak on the shorter wavelength side than light emitted by light-emitting layer 140. Since the luminance of a light-emitting element using a phosphorescent material emitting short-wavelength light tends to degrade rapidly, a short-wavelength fluorescence is used so that a light-emitting element with less luminance degradation can be provided.

[0254] Furthermore, the light-emitting layer 130 and the light-emitting layer 140 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.

[0255] The above structure is also suitable for obtaining white light emission. If light-emitting layer 130 and light-emitting layer 140 emit light in complementary colors, white light emission can be obtained.

[0256] Furthermore, a white light emission with high color rendering properties, composed of three primary colors or four or more colors, can be obtained by using a variety of light-emitting substances emitting light at different wavelengths for one or both of the light-emitting layers 130 and 140. In this case, one or both of the light-emitting layers 130 and 140 can be divided into layers, and each of the divided layers can contain a light-emitting material that differs from that of the others. <Material, das in den Licht emittierenden Schichten verwendet werden kann>

[0257] Next, materials that can be used in the light-emitting layers 120, 130 and 140 are described. <<Material, das in der Licht emittierenden Schicht 120 verwendet werden kann> >

[0258] 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 compound), while the T1 level of the host material 121 is preferably lower than the T1 level of the guest material 122 (the fluorescent material).

[0259] For example, any of the materials described in embodiment 1 as examples of the guest material 132 can be used in the light-emitting layer 120, although the guest material 122 is not particularly restricted.

[0260] 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-(o-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... 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), and 4,4'-Bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB). Furthermore, condensed polycyclic aromatic compounds, such as... B. Anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives and dibenzo[g,p]chrysene derivatives are listed, and specific examples are 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.

[0261] The light-emitting layer 120 can have a structure in which two or more layers are arranged one above the other. For example, if 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, starting from the hole-transport layer side, the first light-emitting layer is formed using a substance with hole-transport properties as the host material, and the second light-emitting layer is formed using a substance with electron-transport properties as the host material.

[0262] 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 130 verwendet werden kann> >

[0263] A material suitable for use in the light-emitting layer 130 can be that used in the light-emitting layer 130 in embodiment 1. Thus, a light-emitting element with high singlet excitation state generation efficiency and high luminous efficacy can be produced. <<Material, das in der Licht emittierenden Schicht 140 verwendet werden kann> >

[0264] The material that can be used in the light-emitting layer 140 is one that can be used in the light-emitting layer 140 in embodiment 2. Thus, a light-emitting element with a low drive voltage can be produced.

[0265] There is no restriction regarding the emission colors of the light-emitting materials contained in the light-emitting layers 120, 130, and 140, 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 those of the light-emitting materials contained in the light-emitting layers 130 and 140.

[0266] It should be noted that the light-emitting units 106, 108, 109 and 110 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.

[0267] The structures described in this embodiment can be used in a suitable combination with any of the structures described in the other embodiments. (Version 4)

[0268] In this embodiment, examples of light-emitting elements with structures that differ from those described in embodiments 1 to 3 are given below, based on: Fig. 7A and Fig. 7B, Fig. 8A and Fig. 8B, Fig. 9A to Fig. 9C and Fig. 10A to Fig. 10C described. <Strukturbeispiel 1 des Licht emittierenden Elements>

[0269] Fig. 7A and Fig. Figure 7B are cross-sectional views, each representing a light-emitting element of an embodiment of the present invention. Fig. 7A and Fig. In some cases, 7B 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.

[0270] Light-emitting elements 260a and 260b in Fig. 7A and Fig. 7B can have a bottom-emission structure in which light is extracted through 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.

[0271] 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.

[0272] 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.

[0273] 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.

[0274] In the light-emitting element 260b, the conductive layer 101b and the conductive layer 101c can be formed with different materials or with 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.

[0275] In the light-emitting element 260b, the electrode 101 can comprise either the conductive layer 101b or the conductive layer 101c.

[0276] 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.

[0277] In Fig. 7A and Fig. 7B is a partition 145 provided between a region 221B, a region 221G and a region 221R, which are arranged between the electrode 101 and the electrode 102. The partition 145 has insulating properties. The partition 145 covers end sections of the electrode 101 and has openings that overlap with 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.

[0278] 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 with the partition 145. The light-emitting layer 123G and the light-emitting layer 123R can overlap each other in an area where they overlap with the partition 145. The light-emitting layer 123R and the light-emitting layer 123B can overlap each other in an area where they overlap with the partition 145.

[0279] 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.

[0280] It should be noted that a silicon oxynitride film is 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 is 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.

[0281] 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.

[0282] One or more of the light-emitting layers 123B, 123G and 123R preferably comprise the light-emitting layer 130 described in embodiment 1 and / or the light-emitting layer 140 described in embodiment 2, wherein in this case a light-emitting element with high luminous efficacy can be produced.

[0283] One or more of the light-emitting layers 123B, 123G and 123R may comprise two or more layers arranged on top of each other.

[0284] If at least one light-emitting layer, as described above, comprises the light-emitting layer described in embodiment 1 or 2, and the light-emitting element 260a or 260b comprising the light-emitting layer is used in pixels of a display device, a display device with high luminous efficacy can be manufactured. The display device, which includes the light-emitting element 260a or 260b, can thus have reduced power consumption.

[0285] 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 through which light is extracted, the color purity of each of the light-emitting elements 260a and 260b can be improved. Consequently, the color purity of a display device incorporating 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 incorporating light-emitting element 260a or 260b can be improved.

[0286] For the other components of the light-emitting elements 260a and 260b, reference can be made to the components of the light-emitting elements in embodiments 1 to 3. <Strukturbeispiel 2 des Licht emittierenden Elements>

[0287] Next, structural examples that differ from the light-emitting elements described in will be presented. Fig. 7A and Fig. 7B will be shown below using the following examples: Fig. 8A and Fig. 8B described.

[0288] Fig. 8A and Fig. Figure 8B shows cross-sectional views of a light-emitting element of an embodiment of the present invention. Fig. 8A and Fig. In some cases, 8B will be a section with a similar function to the one in Fig. 7A and Fig. 7B through the same hatching pattern as in Fig. 7A and Fig. Section 7B 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 not repeated in some cases.

[0289] Fig. 8A and Fig. Figure 8B 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. 8A 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 8B 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.

[0290] The light-emitting elements 262a and 262b each comprise electrode 101, electrode 102, electrode 103, and electrode 104 above the substrate 200. At least one light-emitting layer 170 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, a light-emitting layer 180, 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.

[0291] 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.

[0292] The light-emitting element 262a, which is in Fig. 8A is shown, and the light-emitting element 262b, which is in Fig. As shown in Figure 8B, each 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 with the electrodes. The partition 145 allows the electrodes, which are provided above the substrate 200 in the regions, to be divided into island shapes.

[0293] 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. The 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.

[0294] 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.

[0295] 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 the quantum dot type can increase the color reproducibility of the display device.

[0296] One or more optical elements may be arranged over each of the optical elements 224R, 224G, and 224B. For example, a circularly polarizing plate, an antireflection film, or the like may be provided as an additional optical element. A circularly polarizing plate, provided on the side from which light emitted by the light-emitting element of the display device is extracted, can prevent the phenomenon of light incident from the outside of the display device being 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.

[0297] It should be noted that in Fig. 8A and Fig. 8B 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.

[0298] 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.

[0299] 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.

[0300] It should be noted that optical element 224B and optical element 224G can overlap in an area where they overlap with the opaque layer 223. Furthermore, optical element 224G and optical element 224R can overlap in an area where they overlap with the opaque layer 223. Additionally, optical element 224R and optical element 224B can overlap in an area where they overlap with the opaque layer 223.

[0301] For substrate 200 and substrate 220, which is provided with the optical elements, reference can be made to the substrate of embodiment 1.

[0302] Furthermore, the light-emitting elements 262a and 262b have a microcavity structure. <<Mikrokavitätsstruktur> >

[0303] Light emitted by light-emitting layer 170 and light-emitting layer 180 oscillates between a pair of electrodes (e.g., electrode 101 and electrode 102). Light-emitting layer 170 and light-emitting layer 180 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 region of electrode 101 to the light-emitting region of the light-emitting layer 180, as well as the optical length from the reflective region of electrode 102 to the light-emitting region of the light-emitting layer 180, the light of a desired wavelength can be amplified from the light emitted by the light-emitting layer 180. In the case of a light-emitting element in which a plurality of light-emitting layers (here, the light-emitting layers 170 and 180) are arranged one above the other, the optical lengths of the light-emitting layers 170 and 180 are preferably optimized.

[0304] 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 180 by adjusting the thicknesses of the conductive layers (conductive layer 101b, conductive layer 103b, and conductive layer 104b) in the respective regions. 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 180.

[0305] 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 180, 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 (m R is a natural number and λ R is the wavelength of the light that is amplified in the 222R range).

[0306] In cases where it is difficult to precisely determine the reflective areas of electrodes 101 to 104, the optical length for amplifying the light emitted by light-emitting layer 170 or light-emitting layer 180 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 180, the optical length for amplifying the light emitted by light-emitting layer 170 and light-emitting layer 180 can be derived by assuming that certain areas of light-emitting layer 170 and light-emitting layer 180 are the light-emitting areas.

[0307] In the manner described above, the microcavity structure, in which the optical length between the pair of electrodes is adjusted in the respective regions, suppresses scattering and absorption of light in the vicinity of the electrodes, resulting in high light extraction efficiency. In the structure described above, 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. The conductive layers 101b, 103b, and 104b are preferably formed using the same materials, in which case structuring by etching can be easily carried out. Each of the conductive layers 101b, 103b, and 104b can have a multilayer structure consisting of two or more layers.

[0308] Since the light-emitting element 262a, which is in Fig. As shown in Figure 8A, which has a top-emission structure, the conductive layer 101a, the conductive layer 103a and the conductive layer 104a preferably have a light-reflecting function. Furthermore, the electrode 102 preferably has light-transmitting and light-reflecting functions.

[0309] Since the light-emitting element 262b, which is in Fig. Figure 8B 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.

[0310] 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.

[0311] At least one of the light-emitting layers 170 and 180 in the light-emitting elements 262a and 262b preferably has the structure described in embodiment 1 or 2, in which case light-emitting elements with high light output can be produced.

[0312] One or both of the light-emitting layers 170 and 180 can have a multilayer structure consisting of two layers, such as a light-emitting layer 180a and a light-emitting layer 180b. The two light-emitting layers, containing two types of light-emitting materials (a first light-emitting material and a second light-emitting material) for emitting light of different colors, enable the emission of light in a variety of colors. The light-emitting materials of the light-emitting layers are particularly preferably selected such that white light can be obtained by combining the light emissions from the light-emitting layers 170 and 180.

[0313] One or both of the light-emitting layers 170 and 180 may have a multilayer structure consisting of three or more layers, which may include one layer that does not contain light-emitting material.

[0314] In the manner described above, the light-emitting element 262a or 262b, comprising at least one of the light-emitting layers having the structures described in embodiments 1 and 2, is used in pixels of a display device, thereby enabling the production of a display device with high luminous efficacy. The display device incorporating the light-emitting element 262a or 262b can thus have low power consumption.

[0315] For the other components of the light-emitting elements 262a and 262b, reference can be made to the components of the light-emitting elements 260a and 260b as well as the light-emitting elements in embodiments 1 to 3. <Herstellungsverfahren des Licht emittierenden Elements>

[0316] 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. 9A to Fig. 9C and Fig. 10A to Fig. 10C is described here. A method for producing the light-emitting element 262a, which is described in Fig. 8A is shown and described.

[0317] Fig. 9A to Fig. 9C and Fig. 10A to Fig. Figure 10C are cross-sectional views illustrating a method for manufacturing the light-emitting element of an embodiment of the present invention.

[0318] The following described procedure for producing the light-emitting element 262a comprises a first to seventh step. <<Erster Schritt> >

[0319] 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. 9A).

[0320] 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-Pg-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.

[0321] 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> >

[0322] 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. 9B).

[0323] 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, respectively, which each have 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.

[0324] The conductive layers 101b, 103b, and 104b, which transmit light, can be formed through a variety of steps. When these conductive layers are formed through a variety of steps, they can be designed to have thicknesses that allow for suitable microcavity structures in the respective regions. <<Dritter Schritt> >

[0325] In the third step, the partition 145, which covers the end sections of the electrodes of the light-emitting element, is formed (see Fig. 9C).

[0326] The partition 145 includes 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.

[0327] 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 island shapes by a wet etching process to form the electrodes 101, 103 and 104. <<Vierter Schritt> >

[0328] In the fourth step, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 180, the electron transport layer 113, the electron injection layer 114 and the charge generation layer 115 are formed (see Fig. 10A).

[0329] 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 their respective different evaporation sources. The hole transport layer 112 can be formed by evaporating a hole transport material.

[0330] The light-emitting layer 180 can be formed by evaporating the guest material, which emits light in at least one of the following colors: violet, blue, blue-green, green, yellow-green, yellow, orange, and red. A fluorescent or phosphorescent organic compound can be used as the guest material. Furthermore, the light-emitting layer preferably has any of the structures described in embodiments 1 to 3. The light-emitting layer 180 can have a two-layer structure. In this case, the two light-emitting layers preferably contain light-emitting substances that emit light in different colors.

[0331] 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.

[0332] 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> >

[0333] 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. 10B).

[0334] 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.

[0335] The light-emitting layer 170 can be formed by evaporating the guest material, which emits light in at least one color selected from violet, blue, blue-green, green, yellow-green, yellow, orange, and red. A fluorescent organic compound can be used as the guest material. The fluorescent organic compound alone can be evaporated, or it can be evaporated mixed with another material. For example, the fluorescent organic compound can be used as the guest material and dispersed into a host material that has a higher excitation energy than the guest material.

[0336] 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.

[0337] 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.

[0338] 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> >

[0339] 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. 10C).

[0340] 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> >

[0341] 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).

[0342] The steps described above allow the light-emitting element 262a, which is in Fig. 8A is shown, and will be trained.

[0343] It should be noted that the structures described in this embodiment can be used in a suitable combination with any of the structures described in the other embodiments. (Version 5)

[0344] In this embodiment, a display device of an embodiment of the present invention is described below by reference to Fig. 11A and Fig. 11B, Fig. 12A and Fig. 12B, Fig. 13, Fig. 14A and Fig. 14B, Fig. 15A and Fig. 15B, Fig. 16, Fig. 17A and Fig. 17B, Fig. 18 as well Fig. 19A and Fig. 19B described. <Strukturbeispiel 1 der Anzeigevorrichtung>

[0345] Fig. Figure 11A is a top view showing a display device 600, and Fig. 11 B is a cross-sectional view along the dashed-dotted line AB and the dashed-dotted line CD in Fig. 11A. The display device 600 includes 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.

[0346] The display device 600 also includes 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.

[0347] 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).

[0348] 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.

[0349] The pixel section 602 includes 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.

[0350] To obtain advantageous coverage with a film formed over the partition 614, 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.

[0351] 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 containing 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)).

[0352] 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.

[0353] Furthermore, the EL layer 616 is formed using various methods, 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).

[0354] 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 includes 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.

[0355] 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 the desiccant is provided in the recessed part, whereby deterioration due to the influence of moisture can be prevented.

[0356] An optical element 621 is provided beneath the sealing substrate 604 to overlap with 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 of embodiment 3.

[0357] 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.

[0358] The display device, which includes 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>

[0359] Next, another example of the display device will be given using... Fig. 12A and Fig. 12B as well Fig. 13 described. It should be noted that Fig. 12A and Fig. 12B as well Fig. 13 each represent a cross-sectional view of a display device of an embodiment of the present invention.

[0360] In Fig. Figure 12A 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.

[0361] In Fig. Figure 12A 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 positioned 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. 12A red light, green light and blue light pass through the color layers, and consequently an image can be displayed using pixels of three colors.

[0362] Fig. Figure 12B 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.

[0363] Fig. Figure 13 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.

[0364] 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), but 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>

[0365] Fig. 14A and Fig. Figures 14B are examples of cross-sectional views of a display device with a top-emission structure. It should be noted that Fig. 14A and Fig. 14B 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. 12A and Fig. 12B as well Fig. 13 are shown, but are not shown in these.

[0366] In this case, a light-impermeable substrate 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 can 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 other known materials.

[0367] 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. 14A and Fig. In the display device shown in Figure 14B, 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 is preferably 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.

[0368] In the event of an Fig. The top-emission structure shown in Figure 14A 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.

[0369] Fig. Figure 14A 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 14B shows a structure that includes the red color layer 1034R and the blue color layer 1034B, but no green color layer, to obtain a full-color display with the three colors red, green, and blue. The structure shown in Fig. The structure shown in Figure 14A, 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 14B, 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>

[0370] Although a display device containing 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. 15A and Fig. 15B, Fig. 16 as well Fig. 17A and Fig. 17B represent structures of display devices, each incorporating the lower electrodes 1024R, 1024G, 1024B and 1024Y. Fig. 15A and Fig. 15B as well Fig. 16 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. 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 (top emission structure).

[0371] Fig. 15A 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. 15B 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 16 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.

[0372] 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 can transmit 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 that emits yellow or white light has a high luminous efficacy, the display device incorporating the 1034Y color layer can have low power consumption.

[0373] The top emission indicator devices, which are in Fig. 17A and Fig. Figure 17B shows a light-emitting element comprising the lower electrode 1024Y, preferably 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. 14A is shown. The display device, which is in Fig. As shown in 17A, 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.

[0374] 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 luminous intensity factor, a light-emitting element that emits yellow light has a high luminous efficacy. Consequently, the display device can be used in Fig. 17A reduces power consumption.

[0375] Fig. Figure 17A 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 17B 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 obtain a full-color display with 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 17A 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 17A. Fig. 17B 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>

[0376] Next, a display device of a further embodiment of the present invention will be described using the following examples: Fig. 18 described. Fig. Figure 18 is a cross-sectional view along the dashed-dotted line AB and the dashed-dotted line CD in Fig. 11A. It should be noted that in Fig. 18 sections with functions that are similar to those of the sections in Fig. 11B same, with the same reference symbols as in Fig. are marked 11B, and a detailed description of the sections is omitted.

[0377] The display device 600 in Fig. 18 comprises a sealing layer 607a, a sealing layer 607b, and a sealing layer 607c in 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.

[0378] Alternatively, one or two of the sealing layers 607a, 607b, and 607c can be provided, or four or more sealing layers can be formed. If the sealing layer has a multilayered structure, contaminants, such as water, can be effectively prevented from penetrating from the outside of the display device 600 into the light-emitting element 618 located inside the display device. In the case where the sealing layer has a multilayered structure, a resin and an organic material are preferably arranged one on top of the other. <Strukturbeispiel 6 der Anzeigevorrichtung>

[0379] Although the display devices in 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.

[0380] Fig. 19A and Fig. 19B 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. 19A 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. 19B is 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.

[0381] 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 luminous efficacy, the display device incorporating the light-emitting layer 1028Y can have low power consumption.

[0382] Each of the display devices in Fig. 19A and Fig. 19B does not necessarily include color layers that serve as optical elements, since EL layers that emit light of different colors are contained in subpixels.

[0383] 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.

[0384] Alternatively, the sealing layer 1029 can have a single-layer or 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 organic material are preferably arranged one on top of the other.

[0385] It should be noted that the sealing substrate 1031 has a function of protecting the light-emitting element. Therefore, a flexible substrate or a film can be used for the sealing substrate 1031.

[0386] It should be noted that 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 6)

[0387] In this embodiment, a display device comprising a light-emitting element of an embodiment of the present invention is used by means of Fig. 20A and Fig. 20B, Fig. 21A and Fig. 21B as well Fig. 22A and Fig. 22B described.

[0388] Fig. 20A is a block diagram representing the display device of an embodiment of the present invention, and Fig. Figure 20B is a circuit diagram that represents a pixel circuit of the display device of an embodiment of the present invention. <Beschreibung der Anzeigevorrichtung>

[0389] The display device, which is in Fig. The circuit shown in Figure 20A includes a section containing pixels of display elements (hereinafter referred to as Pixel Section 802), a circuit section provided outside Pixel Section 802 containing circuits for driving the pixels (hereinafter referred to as Driver Circuit Section 804), circuits having a function for protecting elements (hereinafter referred to as Protection Circuits 806), and a terminal section 807. It should be noted that the Protection Circuits 806 are not necessarily provided.

[0390] 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).

[0391] The pixel section 802 includes a variety of circuits for driving the display elements, which are arranged in X rows (X is a natural number of 2 or greater) and Y columns (Y is a natural number of 2 or greater) (hereafter such circuits are referred to as pixel circuits 801). The driver circuit section 804 includes driver circuits, such as a circuit for supplying 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).

[0392] The 804a sample line driver circuit includes a shift register or the like. Via terminal 807, the 804a sample line driver circuit receives a signal to control 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.

[0393] 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 control 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 signal, a clock signal, or the like. Furthermore, the signal line driver circuit 804b 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.

[0394] The 804b signal line driver circuit, for example, includes a variety of analog switches or similar components. By sequentially switching on the various analog switches, the 804b signal line driver circuit can output signals obtained by dividing the video signal in time as data signals. The 804b signal line driver circuit may also include a shift register or similar component.

[0395] 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.

[0396] The in Fig. The protection circuit 806 shown in Figure 20A 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. The protection circuit 806 can also 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 image signals from external circuits are input into the display device.

[0397] 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.

[0398] As in Fig. As shown in Figure 20A, 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.

[0399] In Fig. Figure 20A shows an example in which the driver circuit section 804 includes the sampling line driver circuit 804a and the signal line driver circuit 804b; however, the structure is not limited to this. For example, only the sampling line driver circuit 804a can be formed, and a separately fabricated 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>

[0400] Each of the multitude of 801 pixel circuits in Fig. 20A can, for example, be a Fig. exhibit the structure shown in 20B.

[0401] The in Fig. The pixel circuit 801 shown in Figure 20B includes transistors 852 and 854, a capacitor 862 and a light-emitting element 872.

[0402] 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).

[0403] The 852 transistor has a function to control whether a data signal is written.

[0404] 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.

[0405] The capacitor 862 serves as a storage capacitor for storing the written data.

[0406] 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.

[0407] 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.

[0408] Any of the light-emitting elements described in embodiments 1 to 3 can be used as the light-emitting element 872.

[0409] It should be noted that either the potential supply line VL_a or the potential supply line VL_b is supplied with a high power supply potential VDD, and that the other line is supplied with a low power supply potential VSS.

[0410] For example, the display device uses 801 pixel circuits in Fig. 20B the pixel circuits 801 through the sampling line driver circuit 804a in Fig. 20A is selected sequentially, row by row, which turns on the 852 transistors and writes a data signal.

[0411] 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.

[0412] Alternatively, the pixel circuit can have a function to compensate for fluctuations in the threshold voltages or the like of a transistor. Fig. 21A and Fig. 21B as well Fig. 22A and Fig. 22B provide examples of pixel circuitry.

[0413] The pixel circuitry that is in Fig. The circuit shown in 21A includes 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 diagram 21A 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.

[0414] The pixel circuitry that is in Fig. Figure 21B shows a configuration in which the pixel circuitry shown in Fig. As shown in 21A, a 303_7 transistor is added. The pixel circuit shown in Fig. The transistor shown in diagram 21B 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.

[0415] The pixel circuitry that is in Fig. Figure 22A includes six transistors (transistors 308_1 to 308_6), capacitor 304, and light-emitting element 305. The pixel circuit shown in Fig. The component shown as 22A 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.

[0416] The pixel circuitry that is in Fig. The circuit shown in 22B includes 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 unit shown in diagram 22B 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 diagram 22B, the unit is electrically connected to lines 311_1 to 311_3 and lines 312_1 and 312_2. Fig. As shown in Figure 22B, the pixel circuit can be controlled by a voltage input current driving method (also known as CVCC). It should be noted that, for example, p-channel transistors such as transistors 309_1 and 309_2 can be used.

[0417] 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.

[0418] 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 or achieving higher luminance.

[0419] As an alternative to the active matrix method, the passive matrix method can also be used, in which no active element (no nonlinear element) is employed. Since no active element (no nonlinear element) is used, the number of manufacturing steps is reduced, thus lowering production costs or improving yield. Alternatively, since 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.

[0420] The structure described in this embodiment can be used in a suitable combination with the structure described in any of the other embodiments. (Version 7)

[0421] 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. 23A and Fig. 23B, Fig. 24A to Fig. 24C, Fig. 25A and Fig. 25B, Fig. 26A and Fig. 26B as well Fig. 27 described. <Beschreibung 1 des Touchscreens>

[0422] In this embodiment, a touchscreen 2000, which includes 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 used as the input device.

[0423] Fig. 23A and Fig. Figures 23B are perspective views of the Touchscreen 2000. It should be noted that... Fig. 23A and Fig. For the sake of simplicity, section 23B only shows the main components of the Touchscreen 2000.

[0424] The Touchscreen 2000 includes a display device 2501 and a touch sensor 2595 (see Fig. 23B). The Touchscreen 2000 also includes 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.

[0425] The display device 2501 includes 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).

[0426] The substrate 2590 includes 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. 23B 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.

[0427] 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.

[0428] Examples of projected capacitive touch sensors include self-capacitive and mutual capacitive touch sensors, which differ primarily in their control method. A mutual capacitive type is preferred because it allows for the simultaneous detection of multiple points.

[0429] It should be noted that the touch sensor 2595, which is in Fig. Figure 23B shows an example where a projected capacitive touch sensor is used.

[0430] It should be noted that various sensors can be used as touch sensors 2595, which can detect the approach or touch of a detection object, such as a finger.

[0431] The projected capacitive touch sensor 2595 includes 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.

[0432] 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. 23A and Fig. 23B shown.

[0433] The electrodes 2591 each have a square shape and are arranged in a direction that intersects the direction in which the electrodes 2592 extend.

[0434] A conductor 2594 electrically connects two electrodes 2591, between which the electrode 2592 is positioned. The intersection area of ​​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.

[0435] It should be noted that the shapes of the electrodes 2591 and the electrodes 2592 are not limited and can be any 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 with 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>

[0436] Next, the display device 2501 will be described in detail using the following examples: Fig. 24A described. Fig. 24A corresponds to a cross-sectional view along the dashed line X1-X2 in Fig. 23B.

[0437] The display device 2501 comprises a multitude of pixels arranged in a matrix. Each pixel contains a display element and a pixel circuit for controlling the display element.

[0438] 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.

[0439] 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 for substrate 2510 and substrate 2570 are preferably used whose coefficients of thermal expansion are essentially the same. For example, the coefficients of linear expansion of the materials are preferably less than or equal to 1 × 10 -3 / K, preferably lower than or equal to 5 × 10 -5 / K and even more preferably lower than or equal to 1 × 10 -5 / K.

[0440] 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.

[0441] For adhesive layer 2510c and adhesive layer 2570c, materials such as polyester, polyolefin, polyamide (e.g., nylon, aramid), polyimide, polycarbonate, acrylic, urethane, or epoxy can be used. Alternatively, a material containing a resin with a siloxane bond can be used.

[0442] 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. As shown in 24A, the sealing layer 2560 is taken from the side of the sealing layer 2560, and the sealing layer 2560 can also serve as an optical adhesive layer.

[0443] 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 or 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. Alternatively, a resin, such as acrylic or epoxy, can be used instead of the sealing layer 2560. 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.

[0444] The display device 2501 includes a pixel 2502R. The pixel 2502R includes a light-emitting module 2580R.

[0445] The 2502R pixel contains the 2550R light-emitting element and a 2502t transistor, which supplies electrical energy to the 2550R light-emitting element. It should be noted that the 2502t transistor serves as part of the pixel circuit. The 2580R light-emitting module contains the 2550R light-emitting element and a 2567R color layer.

[0446] 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.

[0447] A microcavity structure can be used between the lower electrode and the upper electrode, so that the intensity of the light with a specific wavelength can be increased.

[0448] 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.

[0449] The color layer 2567R is positioned in an area that overlaps with 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 towards the outside of the light-emitting module 2580R, as indicated by an arrow in Fig. 24A is displayed.

[0450] The display device 2501 includes an opaque layer 2567BM on the light extraction side. The opaque layer 2567BM is arranged such that it surrounds the color layer 2567R.

[0451] 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.

[0452] 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 any 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.

[0453] The light-emitting element 2550R is formed above the insulating layer 2521. A partition 2528 is provided such that it overlaps with an 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.

[0454] A sampling line driver circuit 2503g(1) includes 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.

[0455] 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.

[0456] The display device 2501 can use transistors with any number of different structures. Fig. Figure 24A represents an example where 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 24A. Fig. 24B shown.

[0457] 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 containing 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>

[0458] Next, the 2595 touch sensor will be described in detail using the following examples: Fig. 24C described. Fig. 24C corresponds to a cross-sectional view along the dashed line X3-X4 in Fig. 23B.

[0459] The touch sensor 2595 includes 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.

[0460] 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.

[0461] The electrodes 2591 and the electrodes 2592 can be formed, for example, by 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.

[0462] 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.

[0463] 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 for 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.

[0464] 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.

[0465] Adjacent electrodes 2591 are provided, with an electrode 2592 positioned between them. The conductor 2594 electrically connects the adjacent electrodes 2591.

[0466] 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°.

[0467] 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.

[0468] 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.

[0469] A connection layer 2599 electrically connects the line 2598 to the FPC 2509(2).

[0470] Any of the following anisotropic conductive films (ACF), anisotropic conductive pastes (ACP), and the like can be used as the junction layer 2599. <Beschreibung 2 des Touchscreens>

[0471] Next, the Touchscreen 2000 will be described in detail using the following examples: Fig. 25A described. Fig. 25A corresponds to a cross-sectional view along the dashed line X5-X6 in Fig. 23A.

[0472] The Touchscreen 2000, which is in Fig. The display device 2501, shown in 25A, is based on Fig. 24A has been described, and the touch sensor 2595, which is based on Fig. 24C has been described, attached to each other.

[0473] The Touchscreen 2000, which is in Fig. 25A, in addition to the components shown based on Fig. 24A and Fig. 24C have been described, an adhesive layer 2597 and an anti-reflective layer 2567p.

[0474] 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 with 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.

[0475] The 2567p antireflection layer is positioned in an area that overlaps with pixels. A circularly polarizing plate, for example, can be used as the 2567p antireflection layer.

[0476] Next, a touchscreen with a structure that differs from the one in Fig. 25A is shown, distinguishing it based on Fig. 25B described.

[0477] Fig. 25B is a cross-sectional view of a Touchscreen 2001. The Touchscreen 2001, which is in Fig. The 25B shown differs from the Touchscreen 2000, which is shown in Fig. Figure 25A 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 parts, reference is made to the preceding description of the touchscreen 2000.

[0478] The color layer 2567R is positioned in an area that overlaps with the light-emitting element 2550R. The light-emitting element 2550R, which is in Fig. As shown in figure 25B, light is emitted towards the side where transistor 2502t is located. Consequently, 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 2580R. Fig. 25B is shown.

[0479] The touch sensor 2595 is provided on the side of the substrate 2510 of the display device 2501.

[0480] 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.

[0481] As in Fig. 25A or Fig. As shown in Figure 25B, light from the light-emitting element can be emitted through one or both of the substrates 2510 and 2570. <Beschreibung eines Verfahrens zum Ansteuern des Touchscreens>

[0482] Next, an example of a method for controlling a touchscreen will be given using... Fig. 26A and Fig. 26B described.

[0483] Fig. Figure 26A is a block diagram illustrating the structure of a mutual capacitive touch sensor. Fig. 26A represents a pulse voltage output circuit 2601 and a current sensing circuit 2602. It should be noted that in Fig. 26A 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 the changes in current. Fig. 26A 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.

[0484] 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 occurs in capacitor 2603 (mutual capacitance). The approach or contact of a sensor object can be detected by exploiting this change.

[0485] 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 of a sensing object, while 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.

[0486] Fig. 26B is a time diagram showing the input and output waveforms of the device in Fig. Figure 26A shows a mutually capacitive touch sensor. Fig. 26B involves capturing a capture object in all rows and columns within one frame period. Fig. Figure 26B shows a period in which a detection object is not detected (not touched) and a period in which a detection object is detected (touched). The detected current values ​​of lines Y1 to Y6 are shown in Fig. 26B shown as waveforms of the voltage values.

[0487] 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.

[0488] By detecting a change in mutual capacity in this way, the approach or contact of a detection object can be recorded. <Beschreibung der Sensorschaltung>

[0489] Although Fig. While 26A represents a passive matrix touch sensor in which only the capacitor 2603 is provided as a touch sensor at the intersection of the lines, an active matrix touch sensor can also be used, which includes a transistor and a capacitor. Fig. Figure 27 represents an example of a sensor circuit included in an active matrix touch sensor.

[0490] The sensor circuit in Fig. 27 includes the capacitor 2603 as well as transistors 2611, 2612 and 2613.

[0491] 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.

[0492] Next, the operating principle of the sensor circuit will be described in Fig. As described in section 27, 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.

[0493] Subsequently, the mutual capacitance of capacitor 2603 changes as a result of the approach or contact of a detection object, such as a finger, and accordingly the potential of node n of VRES is changed.

[0494] During a reading operation, 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 detection object can be detected.

[0495] 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.

[0496] The structures described in this embodiment can be used in a suitable combination with any of the structures described in the other embodiments. (Version 8)

[0497] 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. 28, Fig. 29A to Fig. 29G, Fig. 30A to Fig. 30D as well Fig. 31A and Fig. 31B described. <Beschreibung des Anzeigemoduls>

[0498] With a display module 8000 in Fig. 28 are provided 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 between a top cover 8001 and a bottom cover 8002.

[0499] The light-emitting element of an embodiment of the present invention can, for example, be used for the display device 8006.

[0500] 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.

[0501] The touch sensor 8004 can be a resistive touch sensor or a capacitive touch sensor and can be configured to overlap with 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.

[0502] 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.

[0503] 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.

[0504] 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>

[0505] Fig. 29A to Fig. 29G 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, like a pulse sensor and a fingerprint sensor, may have a function for measuring biological information.

[0506] The electronic devices that are in Fig. 29A to Fig. 29G may depict various functions, 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 via a wireless communication function, a function for transmitting and receiving different types of data via a wireless communication function, a function for reading a program or data stored in a storage medium and displaying the program or data on the display section, and the like. It should be noted that functions that can be provided for the electronic devices described in Fig. 29A to Fig. 29G are shown, are not limited to those described above, and the electronic devices may have various functions. Although in Fig. 29A to Fig. Not shown in Section 29G, 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.

[0507] The electronic devices that are in Fig. 29A to Fig. The elements shown in section 29G are described in detail below.

[0508] Fig. Figure 29A 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.

[0509] Fig. Figure 29B 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 laptop, 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. 29B 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 29A. 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; the time; the remaining battery capacity; and the signal strength of an antenna.Instead of the information 9051, the operating buttons 9050 or the like may be displayed in the place where the information 9051 is displayed.

[0510] Fig. Figure 29C is a perspective view of a portable information terminal 9102. The portable information terminal 9102 has a function for displaying information on three or more surfaces of the display section 9001. Here, information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user of the portable information terminal 9102 can view the display (here, information 9053) while the portable information terminal 9102 is placed in a breast pocket of their clothing. In particular, the telephone number, name, or similar information of a caller of an incoming call can be displayed in a location visible from above the portable information terminal 9102. Therefore, the user can view the display without having to remove the portable information terminal 9102 from their pocket and decide whether to answer the call.

[0511] Fig. Figure 29D is a perspective view of a portable information terminal 9200 in the form of a wristwatch. The portable information terminal 9200 can perform various applications, such as making mobile phone calls, sending and receiving emails, displaying and editing texts, playing music, using the internet, and playing computer games. The display surface of the display section 9001 is curved, and images can be displayed on this curved surface. The portable information terminal 9200 can use short-range communication, which is a communication method according to an existing communication standard. For example, in this case, two-way communication can take place between the portable information terminal 9200 and a headset suitable for wireless communication, thus enabling hands-free telephone calls.The 9200 portable information terminal includes the 9006 connection port, and data can be sent and received directly to / from another information terminal via a connection element. Charging via the 9006 connection port is possible. It should be noted that charging can also be performed wirelessly without the 9006 connection port.

[0512] Fig. 29E, Fig. 29F and Fig. 29G are perspective views of a foldable portable information terminal 9201. Fig. Figure 29E is a perspective view showing the Portable Information Terminal 9201 with the opening. Fig. Figure 29F is a perspective view showing the Portable Information Terminal 9201 as opened or folded. Fig. Figure 29G is a perspective view showing the portable information terminal 9201 in its folded state. The portable information terminal 9201 is highly portable when folded. When the portable information terminal 9201 is open, a large, seamless display area is easily searchable. The display section 9001 of the portable information terminal 9201 is supported by three housings 9000 connected by hinges 9055. By folding the portable information terminal 9201 at a junction between two housings 9000 at the hinges 9055, the shape of the portable information terminal 9201 can be reversibly changed from the open state to the folded state. For example, the portable information terminal 9201 can be bent with a radius of curvature greater than or equal to 1 mm and less than or equal to 150 mm.

[0513] Examples of electronic devices include a television set (also called a TV or television receiver), a monitor for a computer or the like, a camera such as a digital camera and a digital video camera, a digital photo frame, a mobile phone (also called a cell phone or portable telephone device), video glasses (a head-worn display), a portable gaming console, a portable information terminal, an audio playback device, and a large gaming machine such as a pachinko machine.

[0514] Fig. Figure 30A represents an example of a television set. In the television set 9300, the display section 9001 is built into the housing 9000. Here, the housing 9000 is supported by a stand 9301.

[0515] The 9300 television set, which is in Fig. The display section 9001, shown in diagram 30A, can be operated using the operating switch on the housing 9000 or using a separate remote control 9311. The display section 9001 may include a touch sensor. The television 9300 can be operated by touching the display section 9001 with a finger or similar object. The remote control 9311 may be equipped with a display section for showing data output by the remote control 9311. The television channels or volume can be controlled, and images displayed on the display section 9001 can be controlled, using the operating buttons or touchscreen of the remote control 9311.

[0516] The 9300 television set is equipped with a receiver, a modem, and similar components. Using the receiver, general television broadcasts can be received. When the television is connected to a communication network via modem, either wirelessly or via cable, unidirectional (from a transmitter to a receiver) or bidirectional (between a transmitter and a receiver or between receivers) data communication can take place.

[0517] The electronic device or lighting device of an embodiment of the present invention is flexible and can therefore be integrated along a curved inner / outer wall surface of a house or building or along a curved inner / outer surface of a car.

[0518] Fig. 30B is an exterior view of a 9700 vehicle. Fig. Figure 30C represents a driver's seat of the vehicle 9700. The vehicle 9700 includes a body 9701, wheels 9702, a dashboard 9703, headlights 9704, and the like. The display device, light-emitting device, or the like of an embodiment of the present invention can be used in a display section or the like of the vehicle 9700. For example, the display device, light-emitting device, or the like of an embodiment of the present invention can be used in display sections 9710 to 9715, which are located in Fig. 30C will be displayed, used.

[0519] Display section 9710 and display section 9711 are each display devices provided in a car windshield. The display device, light-emitting device, or the like of an embodiment of the present invention can be a transparent display device through which the opposite side can be seen by using a translucent conductive material for its electrodes and leads. Such a transparent display section 9710 or 9711 does not obstruct the driver's view while driving the vehicle 9700. Accordingly, the display device, light-emitting device, or the like of an embodiment of the present invention can be provided in the windshield of the vehicle 9700.It should be noted that in the event that a transistor or the like is provided for operating the display device, the light-emitting device or the like, a transistor with a light-transmitting property, such as an organic transistor using an organic semiconductor material or a transistor using an oxide semiconductor, is preferably used.

[0520] Display section 9712 is a display device provided on a pillar section. For example, an image captured by an imaging unit provided in the vehicle body is displayed on display section 9712, thus compensating for the view obstructed by the pillar section. Display section 9713 is a display device provided on the instrument panel. For example, an image captured by an imaging unit provided in the vehicle body is displayed on display section 9713, thus compensating for the view obstructed by the instrument panel. This means that blind spots can be eliminated and safety increased by displaying an image captured by an imaging unit provided on the exterior of the vehicle.By displaying an image to compensate for the area that a driver cannot see, the driver can easily and comfortably check safety.

[0521] Fig. Figure 30D depicts the interior of a car in which bench seats are used as the driver's and passenger's seats. A display section 9721 is a display device provided in a door section. For example, an image captured by an imaging unit provided in the car body is displayed on the display section 9721, thus compensating for the view obstructed by the door. A display section 9722 is a display device provided in a steering wheel. A display section 9723 is a display device provided in the center of a seat cushion. It should be noted that the display device can be used as a seat warmer by placing the display device on the cushion or backrest and using the heat generated by the display device as a heat source.

[0522] Display sections 9714, 9715, and 9722 can provide a variety of information, such as navigation data, a speedometer, a tachometer, an odometer, a fuel gauge, a shift indicator, and air conditioning settings. The content, layout, or other aspects of the display on these sections can be freely modified by the user as needed. The information listed above can also be displayed on display sections 9710 through 9713, 9721, and 9723. Display sections 9710 through 9715 and 9721 through 9723 can also be used as lighting devices. Display sections 9710 through 9715 and 9721 through 9723 can also be used as heaters.

[0523] Furthermore, the electronic device of an embodiment of the present invention can include a secondary battery. Preferably, the secondary battery can be charged by contactless energy transfer.

[0524] Examples of secondary batteries include a lithium-ion secondary battery, such as a lithium polymer battery using a gel electrolyte (lithium-ion polymer battery), a lithium-ion battery, a nickel hydride battery, a nickel-cadmium battery, an organic radical battery, a lead-acid battery, an air secondary battery, a nickel-zinc battery, and a silver-zinc battery.

[0525] The electronic device of an embodiment of the present invention may include an antenna. When a signal is received from the antenna, the electronic device may display an image, data, or the like on a display section. If the electronic device includes a secondary battery, the antenna may be used for contactless power transfer.

[0526] A display device 9500, which is in Fig. 31A and Fig. Figure 31B includes a plurality of display fields 9501, a joint 9511, and a bracket 9512. Each plurality of display fields 9501 comprises a display area 9502 and a translucent area 9503.

[0527] Each of the multiple display fields 9501 is flexible. Two adjacent display fields 9501 are provided in such a way that they partially overlap. For example, the translucent areas 9503 of the two adjacent display fields 9501 can overlap. A display device with a large screen can be obtained using the multiple display fields 9501. The display device is very versatile because the display fields 9501 can be wound up depending on their intended use.

[0528] Although the display areas 9502 of the adjacent display fields 9501 in Fig. 31A and Fig. 31B are separated from each other, the display areas 9502 of the adjacent display fields 9501 can, without being limited to this structure, for example overlap each other without a gap, so that a continuous display area 9502 is obtained.

[0529] The electronic devices described in this embodiment each include a display section for showing certain types of data. It should be noted that the light-emitting element of an embodiment of the present invention can also be used for an electronic device that does not have a display section. The structure in which the display section of the electronic device described in this embodiment is flexible and in which a display can be performed on the curved display surface, or the structure in which the display section of the electronic device is foldable, are described by way of example; however, the structure is not limited to these, and a structure in which the display section of the electronic device is not flexible and a display is performed on a flat surface can also be used.

[0530] The structure described in this embodiment can be used in a suitable combination with the structure described in any of the other embodiments. (Version 9)

[0531] In this embodiment, a light-emitting device is combined with the light-emitting element of an embodiment of the present invention by means of Fig. 32A to Fig. 32C and Fig. 33A to Fig. 33D described.

[0532] Fig. Figure 32A is a perspective view of a light-emitting device 3000 shown in this embodiment, and Fig. 32B is a cross-sectional view along the dashed-dotted line EF in Fig. 32A. It should be noted that in Fig. 32A Some components are represented by dashed lines to avoid complicating the drawing.

[0533] The light-emitting device 3000, which is in Fig. 32A and Fig. Figure 32B includes a ...

Claims

[1] Light-emitting element (250) comprising: a light-emitting layer (120) between a pair of electrodes (102; 103); a host material (121); and a guest material (122), wherein the host material (121) comprises a first organic compound and a second organic compound, wherein the first organic compound is configured to emit thermally activated delayed fluorescence at room temperature, wherein the first organic compound and the second organic compound form an exciplex, and wherein the first organic compound comprises a π-electron-deficient heteroaromatic skeleton. [2] Light-emitting element (250) comprising: a light-emitting layer (120) between a pair of electrodes (102; 103); a host material (121); and a guest material (122), wherein the host material (121) comprises a first organic compound and a second organic compound, where in the first organic compound the difference between a singlet excitation energy level and a triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV, wherein the first organic compound and the second organic compound form an exciplex, and wherein the first organic compound comprises a π-electron-deficient heteroaromatic skeleton. [3] Light-emitting element (250) according to one of claims 1 or 2, wherein the guest material (122) is a phosphorescent compound. [4] Light-emitting element (250) according to one of claims 1 to 3, wherein an emission spectrum of the exciplex has a region which overlaps with an absorption band on the lowest energy side in an absorption spectrum of the guest material (122). [5] Display device (600; 2501; 8006; 9500), comprising: the light-emitting element (250) according to one of claims 1 to 4. [6] Lighting device (8501; 8502; 8503; 8504), comprising: the light-emitting element (250) according to one of claims 1 to 4. [7] Electronic device, comprising: the light-emitting element (250) according to one of claims 1 to 4. [8] Light-emitting element (250) according to one of claims 1 to 4, wherein the first organic compound further comprises a π-electron-rich heteroaromatic framework.

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