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

Abstract

A light-emitting device comprising: an anode; a first light-emitting layer above the anode; a second light-emitting layer above the first light-emitting layer; and a cathode above the second light-emitting layer, wherein the first light-emitting layer comprises a fluorescent substance and a host material, the host material comprising an anthracene framework, wherein the second light-emitting layer comprises a phosphorescent substance, a first organic compound, and a second organic compound, wherein the first organic compound and the second organic compound are configured to form an exciplex, wherein a peak wavelength of light emitted by the first light-emitting layer is shorter than a peak wavelength of light emitted by the second light-emitting layer, wherein the energy value of a peak wavelength of an emission spectrum of the exciplex is a first energy value.where the energy value of a peak wavelength in the absorption band on the side of the lowest energy of the phosphorescent substance is a second energy value, where the difference between the first energy value and the second energy value is less than 0.2 eV, where a triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the fluorescence substance, where the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the first organic compound, and where the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the second organic compound.

Description

Technical field The present invention relates to a light-emitting device. State of the art In recent years, intensive research has been conducted on the development of a light-emitting element (an organic EL element) that utilizes an organic compound and electroluminescence (EL). In a basic structure of such a light-emitting element, an organic compound layer containing a light-emitting substance (an EL layer) is positioned between a pair of electrodes. By applying a voltage to the element, light can be emitted from the light-emitting substance. The light-emitting element is self-illuminating and therefore offers advantages such as high visibility and the absence of a need for backlighting, making it suitable for use in flat panel displays. An additional significant advantage is that a display incorporating this light-emitting element can be manufactured as a thin and lightweight unit with a very fast response time. The light-emitting element can provide planar light emission; therefore, a large-area element can easily be formed. This characteristic is difficult to achieve with point light sources, such as incandescent lamps and LEDs, or linear light sources, such as fluorescent lamps. Therefore, the light-emitting element also has great potential as a planar light source applicable to lighting devices and the like. In the case of such an organic EL cell, electrons from a cathode and holes from an anode are injected into an EL layer, causing an electric current to flow. Recombination of the injected electrons and holes excites the organic compound, which then emits light. The excitation state of an organic compound can be a singlet excitation state (S*) or a triplet excitation state (T*), and light emission from the singlet excitation state is called fluorescence, while light emission from the triplet excitation state is called phosphorescence. The statistical generation ratio of the excitation states for the light-emitting element is assumed to be S*:T* = 1:3. In a compound that emits light from the singlet excitation state (hereinafter referred to as the fluorescent compound), generally no light emission from the triplet excitation state (phosphorescence) is observed at room temperature, while light emission is observed only from the singlet excitation state (fluorescence). Therefore, the internal quantum yield (the ratio of photons produced to charge carriers injected) of a light-emitting element using a fluorescent compound is assumed to have a theoretical limit of 25%, based on the S* to T* ratio of 1:3. In contrast, a compound that emits light from the triplet excitation state (hereinafter referred to as a phosphorescent compound) exhibits light emission from the triplet excitation state (phosphorescence). Since intersystem crossing occurs readily in a phosphorescent compound, the internal quantum yield can theoretically be increased to 100%. This means that a light-emitting element using a phosphorescent compound can easily have a higher emission efficiency than a light-emitting element using a fluorescent compound. For this reason, light-emitting elements using phosphorescent compounds are now being intensively developed to obtain highly efficient light-emitting elements. A white light-emitting element disclosed in patent document 1 comprises a light-emitting region containing various light-emitting dopants that emit phosphorescence. An element disclosed in patent document 2 comprises an intermediate layer (a charge-generating layer) between a fluorescent layer and a phosphorescent layer (i.e., the element is a so-called tandem element). US 2013 / 0 069 044 A1 discloses devices with at least one hole transport layer, two light-emitting layers, and one electron transport layer, each having one highest occupied molecular orbital (HOMO) energy level and one lowest unoccupied molecular orbital (LUMO) energy level, wherein at least one of the HOMO and / or LUMO energy levels of at least one of the light-emitting layers does not decrease stepwise.US Patent 2011 / 0 215 714 A1 describes a light-emitting element with improved power efficiency that emits light with a natural color, similar to that of an incandescent bulb. US Patent 2013 / 0 324 733 A1 describes a novel dinuclear metal complex containing a biimidazole as a bridging ligand. This dinuclear metal complex can be used as a material for an organic electroluminescent element. US Patent 2011 / 0 133 227 A1 discloses an organic light-emitting diode device comprising a luminescent layer containing at least two blue luminescent units and at least one orange luminescent unit. [Reference] Patent Document 1: Japanese translation of the international PCT application JP 2004 - 522 276 A Patent Document 2: Japanese patent disclosure JP 2006 - 24 791 A Disclosure of the invention As multicolored light-emitting elements, similar to typical white light-emitting elements, elements with an intermediate layer (a charge-generating layer) between a fluorescent layer and a phosphor layer have been developed (Patent Document 2), and some of them have been implemented in practice. In the light-emitting element with such a structure, light with a short wavelength is emitted by the fluorescent layer, and light with a long wavelength is emitted by the phosphor layer. In this structure, fluorescence is used as the short-wavelength light source, which has a lifetime problem, and phosphorescence is used as the long-wavelength light source. This structure is employed to achieve stable properties in a multicolored light-emitting element, although its efficiency is lower than that of an element that uses both long-wavelength and short-wavelength phosphorescence. The multicolored light-emitting element, which has the structure described above and prioritizes reliability over performance, is suitable for practical use compared to general light-emitting elements, which often still have a problem with lifetime; however, a larger number of films are produced for the sake of a multicolored light-emitting element, which prevents its practical implementation. There are several reasons for providing the intermediate layer between the phosphor layer and the fluorescent layer in the multicolored element with this structure. One of the reasons is to suppress the quenching of phosphorescence caused by the fluorescent layer. In a fluorescent layer, a substance with a fused aromatic ring framework (especially a fused aromatic hydrocarbon ring framework), such as typically anthracene, is generally used as the host material. Substances with the fused aromatic ring framework often have a relatively low triplet level. Accordingly, when the fluorescent layer forms in contact with a phosphor layer, the triplet excitation energy generated in the phosphor layer is transferred to the triplet level of the host material in the fluorescent layer and dissipated. Since a triplet exciton has a long lifetime, the exciton diffusion length is long, and excitation energy generated in the phosphor layer, as well as excitation energy generated at the interface between the fluorescent and phosphor layers, is dissipated by the host material in the fluorescent layer.Therefore, there is a significant reduction in emission efficiency. The problems described above are solved by using a host material with a high triplet excitation energy for the fluorescent layer. However, in this case, the singlet excitation energy of the host material is higher than the triplet excitation energy, so the energy is not sufficiently transferred from the host material to the fluorescent dopant. This results in insufficient emission efficiency in the fluorescent layer. Furthermore, non-radiative decay of the host material is accelerated, thus degrading the element's properties (especially its lifetime). If the singlet excitation energy of the host material is higher than necessary, the HOMO-LUMO gap of the host material is large, leading to an excessive increase in the operating voltage. In light of the above, one object of an embodiment of the present invention is to provide a light-emitting element that utilizes fluorescence and phosphorescence and is suitable for practical application. A further object of an embodiment of the present invention is to provide a light-emitting element that utilizes fluorescence and phosphorescence, requires a small number of manufacturing steps due to a relatively small number of layers to be formed, and is suitable for practical application. Another object of an embodiment of the present invention is to provide a light-emitting element that utilizes fluorescence and phosphorescence and has a high emission efficiency. Another object of an embodiment of the present invention is to provide a light-emitting element that utilizes fluorescence and phosphorescence, has a relatively small number of layers to be formed, is suitable for practical application, and exhibits high emission efficiency. A further object according to 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 display module, a lighting module, a light-emitting device, a display device, an electronic device and a lighting device that can be manufactured at low cost by using the light-emitting element. Another object of an embodiment of the present invention is to provide a display module, a lighting module, a light-emitting device, a display device, an electronic device and a lighting device that have reduced power consumption by using the light-emitting element. It is only necessary that at least one of the above-described problems is fulfilled by the present invention. The tasks described above are solved by a light-emitting device according to one of claims 1, 2, 3 or 5. Further embodiments are specified in claims 4 and 6. Brief description of the drawings Figures 1A and 1B are conceptual diagrams of light-emitting elements. Figures 2A and 2B are conceptual diagrams of a light-emitting active matrix device. Figures 3A and 3B are conceptual diagrams of light-emitting active matrix devices. Figure 4 is a conceptual diagram of a light-emitting active matrix device. Figures 5A and 5B are conceptual diagrams of a light-emitting passive matrix device. Figures 6A and 6B depict a lighting device. Figures 7A, 7B1, 7B2, 7C, and 7D depict electronic devices. Figure 8 depicts a light source device. Figure 9 depicts a lighting device. Figure 10 depicts a lighting device. Figure 11 depicts display devices and lighting devices in the vehicle. Figures 12A to 12C depict an electronic device. Figure 13 shows the current density-luminance properties of a light-emitting element 1.Figure 14 shows luminance-current efficiency properties of the light-emitting element 1. Figure 15 shows voltage-luminance properties of the light-emitting element 1. Figure 16 shows luminance-external quantum efficiency properties of the light-emitting element 1. Figure 17 shows an emission spectrum of the light-emitting element 1. Figure 18 shows the time dependence of the normalized luminance of the light-emitting element 1. Figures 19A and 19B show emission spectra of a light-emitting element 2 and a light-emitting element 3. Figure 20 shows an emission spectrum of a light-emitting element 4. Figure 21 shows a correlation between energy levels of substances and exciplexes in a light-emitting element of an embodiment of the present invention. Best way to implement the invention Embodiments of the present invention are described below with reference to the drawings. It should be noted that the present invention is not limited to the following description, and it is readily apparent to a person skilled in the art that various changes and modifications can be made without departing from the concept and scope of protection of the present invention. Accordingly, the invention should not be considered as limited to the description in the following embodiments. (Version 1) Fig. 1A is a schematic representation of a light-emitting element of an embodiment of the present invention. The light-emitting element comprises at least one pair of electrodes (a first electrode 101 and a second electrode 102) and an EL layer 103, which includes a light-emitting layer 113. The light-emitting layer 113 comprises the first light-emitting layer 113a and the second light-emitting layer 113b. Fig. 1A also shows a hole injection layer 111, a hole transport layer 112, an electron transport layer 114, and an electron injection layer 115 in the EL layer 103. However, this multilayer structure is an example, and the structure of the EL layer 103 in the light-emitting element of an embodiment of the present invention is not limited to this. It should be noted that in Fig. 1A, the first electrode 101 serves as the anode and the second electrode 102 serves as the cathode. The first light-emitting layer 113a contains a fluorescent substance and a host material. The second light-emitting layer 113b contains a first organic compound, a second organic compound, and a phosphorescent compound. In the light-emitting layer with the structure, a combination of the first organic compound and the second organic compound forms an exciplex. This structure allows light originating from the fluorescent substance to be efficiently emitted by the first light-emitting layer 113a, and light originating from the phosphorescent substance to be efficiently emitted by the second light-emitting layer 113b. It should be noted that even if the light-emitting element does not include a charge-generating layer between the first light-emitting layer 113a and the second light-emitting layer 113b (i.e., if the light-emitting element is not a tandem element), both fluorescence and phosphorescence can be efficiently maintained. When a fluorescent layer and a phosphor layer are contained within the same electron beam junction (EL) layer, causing light emission, the triplet excitation energy of the phosphor layer is generally transferred to a host material occupying a large portion of the fluorescent layer. This leads to a significant reduction in emission efficiency. The reason is as follows: Since a substance with a condensed aromatic ring framework (especially a condensed aromatic hydrocarbon ring framework), such as typically anthracene with a low triplet level, is generally used as the host material, the triplet excitation energy generated in the phosphor layer is transferred to the host material in the fluorescent layer, resulting in non-radiative decay.Currently, it is difficult to obtain a desired emission wavelength and advantageous elemental properties or reliability without using a substance with a condensed aromatic ring framework in the fluorescence layer; therefore, it is difficult to obtain a light-emitting element with advantageous properties in the structure where the fluorescence layer and the phosphorescence layer are contained in the same EL layer. Since a triplet excitation state has a long relaxation time, the diffusion length of an exciton is long, and most of the excitons generated in the phosphor layer are transferred to the fluorescence layer as a result of diffusion, leading to non-radiative decay of the excitons. This further reduces the emission efficiency of the phosphor layer. In this embodiment, the first and second organic compounds in the second light-emitting layer 113b form an exciplex, and the triplet excitation energy is transferred from the exciplex to the phosphorescent substance, thus enabling light emission. This structure can solve the problems described above. An exciplex is an excited state formed by two types of substances. These two substances, which formed the exciplex, return to a ground state as a result of light emission, thus functioning as the original two substances. In other words, an exciplex itself does not possess a ground state, and therefore, in principle, energy transfer between exciplexes or energy transfer to an exciplex from another substance is unlikely to occur. A process in which one of the first and second organic compounds are adjacent as a cation and the other as an anion, forming an exciplex (an electroplex process), is considered dominant for exciplex generation in the light-emitting element. Even if one of the first and second organic compounds reaches an excited state, it rapidly interacts with the other adjacent compound to form an exciplex; therefore, most excitons in the second light-emitting layer 113b are found as exciplexes. The singlet excitation energy of an exciplex corresponds to an energy difference between the lower HOMO level of one of the first organic compound and the second organic compound and the higher LUMO level of the other of the first organic compound and the second organic compound; consequently, the singlet excitation energy of the exciplex is lower than the singlet excitation energy of the two organic compounds, and no singlet excitation energy transfer occurs from the exciplex to the first organic compound and the second organic compound.Furthermore, the first and second organic compounds are selected such that the triplet excitation energy of the exciplex is lower than the triplet excitation energy of either the first or the second organic compound, preferably lower than the triplet excitation energy of both the first and second organic compounds, thus minimizing energy transfer from one exciplex to the first and second organic compounds. Moreover, as described above, energy transfer between the exciplexes is minimal; therefore, exciton diffusion into the second light-emitting layer 113b is minimal. Consequently, the problems described above can be solved. When the first light-emitting layer 113a, which is a fluorescent layer, and the second light-emitting layer 113b are in contact, energy transfer (in particular, triplet energy transfer) from the exciplex to the host material of the first light-emitting layer 113a can occur at the interface. However, as described above, diffusion of the excitons into the second light-emitting layer 113b is minimal; therefore, energy transfer from the exciplex to the host material in the first light-emitting layer 113a occurs only in a limited region (i.e., at the interface between the first light-emitting layer 113a and the second light-emitting layer 113b), with no significant loss of excitation energy.Therefore, a special feature of one embodiment of the present invention is that high efficiency can be achieved even when the first light-emitting layer 113a and the second light-emitting layer 113b are in contact with each other, although the light-emitting layers are not necessarily in contact with each other. In other words, an elemental structure is also an embodiment of the present invention in which the first light-emitting layer 113a and the second light-emitting layer 113b are in contact with each other. Even if, as described above, the triplet excitation energy of the host material contained in the fluorescence layer is lower than the triplet excitation energy of the first organic compound and the second organic compound contained in the phosphorescence layer, the application of an embodiment of the present invention enables a light-emitting element to emit fluorescence and phosphorescence with high efficiency. Furthermore, in the light-emitting element of an embodiment of the present invention, even if an energy transfer (in particular a triplet energy transfer) from the exciplex to the host material in the first light-emitting layer 113a or an energy transfer from the phosphorescent substance to the host material in the first light-emitting layer 113a occurs at the interface between the first light-emitting layer 113a and the second light-emitting layer 113b, the energy can be converted into luminescence in the first light-emitting layer 113a.In other words, if the first light-emitting layer 113a has a structure in which a singlet excitation state is readily generated by triplet-triplet annihilation (TT-annihilation, TTA), the triplet excitation energy transferred from the exciplex to the host material at the interface can be converted into fluorescence in the first light-emitting layer 113a. This allows the energy loss of the light-emitting element of an embodiment of the present invention to be reduced.To enable the light-emitting layer 113a to have a structure in which the singlet excitation state is readily generated by TTA, a host material and a fluorescent substance in the first light-emitting layer 113a are preferably selected such that the singlet excitation level of the host material is higher than the singlet excitation level of the fluorescent substance, and the triplet excitation level of the host material is lower than the triplet excitation level of the fluorescent substance. A preferred combination of host material and fluorescent substance in such a relationship is a material with an anthracene framework as the host material and a material with a pyrene framework as the fluorescent substance, or the like. It should be noted that if the first light-emitting layer 113a is too thick, emission from the second light-emitting layer 113c is difficult to obtain. Furthermore, if the first light-emitting layer 113a is too thin, emission from the first light-emitting layer 113a is difficult to obtain. For these reasons, the thickness of the first light-emitting layer 113a is preferably greater than or equal to 5 nm and less than or equal to 20 nm. If the first light-emitting layer 113a is formed on the anode side, it preferably exhibits hole transport properties. In this case, a bipolar material with high hole transport properties is preferably used. A material with an anthracene framework is preferred as such a material. Furthermore, if the fluorescent substance has hole-trapping properties (e.g., a condensed aromatic amine compound described below), the concentration of the fluorescent substance is preferably less than or equal to 5%, more preferably greater than or equal to 1% and less than or equal to 4%, and even more preferably greater than or equal to 1% and less than or equal to 3%, whereby phosphorescence and fluorescence can be obtained in a balanced manner and with high efficiency.It should be noted that the fluorescent substance exhibits hole-trapping properties when the HOMO level of the fluorescent substance is higher than the HOMO level of the host material. Although there is no restriction on the combination of the first and second organic compounds in the second light-emitting layer 113b, as long as an exciplex can be formed, one organic compound is preferably a material with hole transport properties and the other organic compound is preferably a material with electron transport properties. In this case, a donor-acceptor excitation state is readily formed, which allows an exciplex to be formed efficiently. If the combination of the first and second organic compounds is a combination of the material with hole transport properties and the material with electron transport properties, the carrier balance can be easily controlled by regulating the mixing ratio.In particular, the weight ratio of the material with hole transport properties to the material with electron transport properties is preferably 1:9 inclusive to 9:1 inclusive. To increase the quantum yield, the weight ratio of the material with hole transport properties to the material with electron transport properties is particularly preferably 5:5 inclusive to 9:1 inclusive in a region closest to the anode in the second light-emitting layer 113b. Since the charge carrier balance in the light-emitting element with the structure described above can be easily controlled, a recombination range can also be easily regulated. The light-emitting element of an embodiment of the present invention also has the feature that an emission color can be regulated by controlling the charge carrier balance as described above. In the light-emitting element of this embodiment, a charge carrier recombination region is preferably distributed to a certain extent. For this purpose, each light-emitting layer preferably exhibits an appropriate degree of charge carrier capture property, and the phosphorescent substance particularly preferably exhibits electron capture property. Examples of a substance exhibiting high electron capture property include transition metal complexes (e.g., an iridium complex and a platinum complex) whose ligands comprise a diazine framework, such as a pyrimidine or pyrazine framework. It should be noted that the phosphorescent substance exhibits electron capture property if its LUMO level is lower than the LUMO levels of both the first and second organic compounds. It should be noted that in the light-emitting element, the light emitted by the first light-emitting layer 113a preferably exhibits a peak on the shorter wavelength side than the light emitted by the second light-emitting layer 113b. The luminance of a light-emitting element using a short-wavelength phosphorescent substance tends to degrade rapidly. Therefore, short-wavelength fluorescence is used, allowing for a light-emitting element with less luminance degradation. The number and thickness of layers forming the EL layer in the light-emitting element of one embodiment of the present invention are smaller than in a tandem element; therefore, the light-emitting element of one embodiment of the present invention is cost-effective and suitable for mass production. Furthermore, as described above, the number of layers forming the EL layer is small; consequently, the thickness of the EL layer can be small, and the light-emitting element is optically advantageous (e.g., the extraction efficiency is high). In addition, the light-emitting element can have a low operating voltage and efficiently provide both fluorescence and phosphorescence at an operating voltage of 5 V or lower. Furthermore, although the fluorescence layer and the phosphorescence layer are in contact with each other, a decay of the triplet excitation energy as a result of the use of the exciplex described above is less likely to occur; therefore, both phosphorescence and fluorescence can be easily obtained. Fig. 21 shows a correlation between energy levels of substances and exciplexes in the light-emitting element described in this embodiment. In Fig. 21, SFH denotes the singlet excitation level of the host material in the first light-emitting layer 113a; TFH the triplet excitation level of the host material in the first light-emitting layer 113a; SFG and TFG the singlet excitation level and triplet excitation level, respectively, of a guest material (the fluorescent substance) in the first light-emitting layer 113a; SPH and TPH the singlet excitation level and triplet excitation level, respectively, of a host material (the first organic compound or the second organic compound) in the second light-emitting layer 113b; SE and TE the singlet excitation level and triplet excitation level, respectively.the triplet excitation level of the exciplex in the second light-emitting layer 113b; and TPG the triplet excitation level of a guest material (the phosphorescent substance) in the second light-emitting layer 113b. As shown in Fig. 21, TTA occurs because triplet excitation molecules of the host materials collide in the first light-emitting layer 113a, and some of the host material's triplet excitation molecules are converted into singlet excitation molecules, while others thermally decay. The singlet excitation energy of the host materials, generated by TTA, is then transferred to the singlet excitation state of the fluorescent substance, and the singlet excitation energy is converted into fluorescence. In the second light-emitting layer 113b, the excitation levels SE and TE of the exciplex are lower than the excitation levels SPH and TPH of the host materials (the first and second organic compounds); therefore, no excitation energy transfer occurs from the exciplex to the host material. Furthermore, no energy transfer occurs from one exciplex to another. When the excitation energy of the exciplex is transferred to the host material (the phosphorescent substance), the excitation energy is converted into luminescence. As described above, the triplet excitation energy hardly diffuses and is converted into luminescence in the second light-emitting layer 113b. Since the triplet excitation energy hardly diffuses, despite a small energy transfer at the interface between the first light-emitting layer 113a and the second light-emitting layer 113b (e.g., energy transfer from TPG of the phosphorescent substance at the interface to TFH or TFG), light emission with high efficiency can be obtained from both the first light-emitting layer 113a and the second light-emitting layer 113b. It should be noted that in the first light-emitting layer 113a, the singlet excitation state is generated by the triplet excitation energy at TTA, and that some of the energy transfer at the interface is converted into fluorescence. This can suppress the energy loss. In the light-emitting element of this embodiment, the first light-emitting layer 113a and the second light-emitting layer 113b are arranged to emit light with different emission wavelengths, so that the light-emitting element can be a multicolored light-emitting element. The emission spectrum of the light-emitting element is formed by combining light with different emission peaks and therefore has at least two peaks. Such a light-emitting element is suitable for obtaining white light. If the first light-emitting layer 113a and the second light-emitting layer 113b emit light with complementary colors, white light emission can be obtained. Furthermore, white light emission with high color rendering properties, composed of three colors or four or more colors, can be obtained by using a variety of light-emitting substances emitting light of different wavelengths for one or both of the light-emitting layers. In this case, each of the light-emitting layers can be divided into sublayers, and the sublayers can contain different light-emitting substances. The absorption band on the side of the lowest energy of the phosphor overlaps the emission spectrum of the exciplex in the second light-emitting layer 113b, thereby enabling the light-emitting element to exhibit a higher emission efficiency. The difference between the equivalent energy values ​​of a peak wavelength in the absorption band on the side of the lowest energy of the phosphor and a peak wavelength of the emission spectrum of the exciplex is preferably less than or equal to 0.2 eV, with a large overlap between the absorption band and the emission spectrum.Although the absorption band on the side of the lowest energy of the phosphorescent substance is preferably an absorption band of the triplet excitation level, the absorption band on the side of the lowest energy is preferably an absorption band of the singlet excitation level when a TADF material is used instead of the phosphorescent substance, as described below. In Fig. 1A, the first light-emitting layer 113a is formed on the side where the first electrode 101, which serves as the anode, is formed, and the second light-emitting layer 113b is formed on the side where the second electrode 102, which serves as the cathode, is formed. However, the order of the layers can be reversed. In other words, the first light-emitting layer 113a can be formed on the side where the second electrode 102, which serves as the cathode, is formed, and the second light-emitting layer 113b can be formed on the side where the first electrode 101, which serves as the anode, is formed. It should be noted that the structure of the light-emitting element in this embodiment is effective as long as the light-emitting substance in the second light-emitting layer 113b can convert the triplet excitation level into luminescence. In the following description, a "phosphorescent substance" can be replaced by a "thermally activated delayed fluorescent (TADF) material," and a "phosphorescent layer" can be replaced by a "TADF layer." The TADF material is a substance that can up-convert a triplet excitation state to a singlet excitation state (i.e., reverse intersystem crossing is possible with it), using low thermal energy, and efficiently emits light (fluorescence) from the singlet excitation state.The TADF is efficiently obtained under the condition that the energy difference between the triplet excitation level and the singlet excitation level is greater than or equal to 0 eV and less than or equal to 0.2 eV, preferably greater than or equal to 0 eV and less than or equal to 0.1 eV. Both the phosphorescent substance and the TADF material are substances capable of converting the triplet excitation energy into luminescence. (Version 2) In this embodiment, a detailed example of the structure of the light-emitting element described in embodiment 1 is described below with reference to Fig. 1A and Fig. 1B. In this embodiment, a light-emitting element comprises an EL layer, which includes a plurality of layers, between a pair of electrodes. In this embodiment, the light-emitting element includes the first electrode 101, the second electrode 102, and the EL layer 103, which is arranged between the first electrode 101 and the second electrode 102. It should be noted that in this embodiment, the first electrode 101 serves as the anode and the second electrode 102 serves as the cathode. In other words, light emission can be obtained when a voltage is applied between the first electrode 101 and the second electrode 102 such that the potential of the first electrode 101 is higher than that of the second electrode 102. Since the first electrode 101 serves as the anode, it is preferably formed using one of the following metals, alloys, electrically conductive compounds with a high work function (in particular, a work function of 4.0 eV or more), mixtures thereof, and the like. Specific examples include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). Films of these electrically conductive metal oxides are usually formed by a sputtering process; however, they can also be formed by a sol-gel process or the like. For example, indium zinc oxide is deposited by a sputtering process using a target obtained by adding 1 wt.% to 20 wt.% zinc oxide to indium oxide.An indium oxide film containing tungsten oxide and zinc oxide (IWZO) can be formed by a sputtering process using a target in which 0.5 wt% to 5 wt% tungsten oxide and 0.1 wt% to 1 wt% zinc oxide are added to the indium oxide. Gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), nitrides of metallic materials (e.g., titanium nitride), and the like can also be specified. Graphene can also be used. It should be noted that if a composite material described later is used for a layer in contact with the first electrode 101 in the EL layer 103, an electrode material can be selected regardless of its work function. There is no particular restriction regarding the multilayer structure of the EL layer 103, as long as the light-emitting layer 113 has the structure described in embodiment 1. For example, the EL layer 103 can be configured by appropriately combining a hole injection layer, a hole transport layer, the light-emitting layer, an electron transport layer, an electron injection layer, a charge carrier barrier layer, an intermediate layer, and the like. In this embodiment, the EL layer 103 has a structure in which the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, the electron transport layer 114, and the electron injection layer 115 are layered over the first electrode 101 in that order. Specific examples of materials used for each layer are given below. The hole injection layer 111 is a layer containing a substance with high hole injection properties. Molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, or the like can be used. Alternatively, the hole injection layer 111 can be made using a phthalocyanine-based compound, such as phthalocyanine (abbreviation: H₂Pc) or copper phthalocyanine (abbreviation: CuPc); an aromatic amine compound, such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD); a high-molecular-weight compound, such as... B. Poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS); or the like. Alternatively, a composite material containing a substance with hole-transporting properties and a substance with acceptor properties can be used for the hole injection layer 111. It should be noted that using such a substance with hole-transporting properties and an acceptor allows the material for forming an electrode to be selected independently of its work function. In other words, in addition to a material with a high work function, a material with a low work function can be used for the first electrode 101. Acceptor substances can include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, and the like. Furthermore, transition metal oxides can be used. Additionally, oxides of metals belonging to groups 4 to 8 of the periodic table can be employed.Vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are particularly preferred due to their high electron acceptor properties. Among these, molybdenum oxide is especially favored because it is stable in air, exhibits low hygroscopicity, and is easy to handle. A variety of organic compounds, such as aromatic amines, carbazole derivatives, aromatic hydrocarbons, and high-molecular-weight compounds (e.g., oligomers, dendrimers, or polymers), can be used as the substance with hole transport properties in the composite material. It should be noted that the organic compound for the composite material is preferably one with high hole transport properties. In particular, a substance with a hole mobility of 10⁻⁶ cm² / Vs or higher is preferably used. Specific examples of organic compounds that can be used as substances with hole transport properties in the composite material are given below. Examples of aromatic amine compounds 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) and 1,3,5-Tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B). Specific examples of the carbazole derivatives that can be used for the composite material are 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) and 3-[N-(1-Naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1). Other examples of carbazole derivatives that can be used for the composite material 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) and 1,4-Bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene. Examples of aromatic hydrocarbons that can be used for the composite material 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, and 2,5,8,11-tetra(tert-butyl)perylene. Other examples include pentacene and coronene.The aromatic hydrocarbon having a hole mobility of 1 × 10-6cm2 / Vs or higher and having 14 to 42 carbon atoms is particularly preferred. It should be noted that the aromatic hydrocarbons that can be used for the composite material may have a vinyl backbone. Examples of aromatic hydrocarbons with a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA). 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). By providing a hole injection layer, a high hole injection property can be achieved, which allows a light-emitting element to be operated at a low voltage. The hole transport layer 112 is a layer containing a substance with hole transport properties. Examples of substances with hole transport properties are aromatic amine compounds, such as... B. 4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-Bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',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) and 4-Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP). The substances listed here exhibit high hole transport properties and are mainly those that have a hole mobility of 10-6cm2 / Vs or higher.An organic compound, which has been given as an example of a substance with hole transport properties in the composite material described above, can also be used for the hole transport layer 112. Furthermore, a high-molecular-weight compound, such as poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphenylamine) (abbreviation: PVTPA), can also be used. It should be noted that the layer containing a substance with hole transport properties is not limited to a single layer and can be an arrangement of two or more layers containing one of the aforementioned substances. When the first light-emitting layer 113a is arranged on the anode side of the light-emitting element of an embodiment of the present invention, the HOMO level of a substance used for the hole transport layer 112 and the HOMO level of a host material in the first light-emitting layer 113a are preferably close to each other (an energy difference of 0.2 eV or less). This can prevent too many holes from being trapped by capture states and allows holes to flow into the first light-emitting layer 113a and the second light-emitting layer 113b. Therefore, fluorescence and phosphorescence can be easily obtained in a balanced manner with high efficiency. The light-emitting layer 113 has the structure of the light-emitting layer 113 described in embodiment 1. In other words, the first light-emitting layer 113a and the second light-emitting layer 113b are layered over the first electrode in that order. A host material and a fluorescent substance are contained in the first light-emitting layer 113a. A first organic compound, a second organic compound, and a substance that can convert the triplet excitation energy into luminescence (a phosphorescent compound or a TADF material) are contained in the second light-emitting layer 113b. In the light-emitting element of this embodiment, a combination of the first organic compound and the second organic compound forms an exciplex.The exciplex can provide energy for the substance that can convert the triplet excitation energy into luminescence, so that light can be efficiently emitted from both the first light-emitting layer 113a and the second light-emitting layer 113b. Examples of materials that can be used as fluorescent substances in the first light-emitting layer 113a are given below. Other fluorescent materials besides those given below may also be used. Examples of the fluorescent substance are 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'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-diphenyl-pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-Bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-Diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), Perylene, 2,5,8,11-Tetra-tert-butylperylene (abbreviation: TBP) 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N"-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N",N-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-Diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-Diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N",N",N",N"',N"'-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-Diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-Diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-Bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-Triphenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-Diphenylquinacridone (abbreviation: DPQd), Rubren, 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}propanedinitrile (abbreviation: DCJTB), 2-(2,6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM) and 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). Condensed aromatic diamine compounds, such as typically pyrenediamine compounds like 1,6FLPARN and 1,6mMemFLPARN, are particularly preferred due to their high hole-trapping properties, high emission efficiency, and high reliability. Examples of a compound that can be used as a host material in the first light-emitting layer 113a are given below. Examples include anthracene compounds such as 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-Diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA) and 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl}anthracene (abbreviation: FLPPA). The use of a substance with an anthracene backbone as a host material enables the creation of a light-emitting layer with high emission efficiency and durability. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are especially preferred due to their excellent properties. A phosphorescent substance and a TADF material can be used in the second light-emitting layer 113b as substances capable of converting the triplet excitation energy into luminescence. Examples of the phosphorescent substance and the TADF material are described below. Examples of the phosphorescent substance are an organometallic iridium complex with a 4H-triazole skeleton, such as Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC} iridium(III) (abbreviation: Ir(mpptz-dmp)3), Tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(Mptz)3) or Tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(iPrptz-3b)3); an organometallic iridium complex with a 1H-triazole skeleton, such as... B. Tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(Mptz1-mp)3) or Tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(Prptz1-Me)3); a metal-organic iridium complex with an imidazole skeleton, such asfac-Tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: Ir(iPrpmi)3) or Tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: Ir(dmpimpt-Me)3); and an organometallic iridium complex in which a phenylpyridine derivative with an electron-withdrawing group is a ligand, such as fac-Tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole ...iPrpmi)3). Examples include Bis[2-(4',6'-difluorophenyl)pyridinato-N,C2']iridium(III)tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), Bis[2-(4',6'-difluorophenyl)pyridinato-N,C2']iridium(III)picolinate (abbreviation: FIrpic), Bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C2'}iridium(III)picolinate (abbreviation: Ir(CF3ppy)2(pic)), and Bis[2-(4',6'-difluorophenyl)pyridinato-N,C2']iridium(III)acetylacetonate (abbreviation: FIr(acac)). These compounds emit blue phosphorescence and exhibit an emission peak at 440 nm to 520 nm. Other examples include organometallic iridium complexes with pyrimidine skeletons, 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[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(nbppm)2(acac)). (Acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(mpmppm)2(acac)) and (Acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: Ir(dppm)2(acac)); organometallic iridium complexes with pyrazine skeletons, 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 pyridine skeletons, such as... B. Tris(2-phenylpyridinato-N,C2')iridium(III) (abbreviation: Ir(ppy)3), Bis(2-phenylpyridinato-N,C2')iridium(III)acetylacetonate (abbreviation: Ir(ppy)2acac)), Bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: Ir(bzq)2(acac)), Tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq)3), Tris(2-phenylquinolinato-N,C2')iridium(III) (abbreviation: Ir(pq)3) and Bis(2-phenylquinolinato-N,C2')iridium(III)acetylacetonate (abbreviation: Ir(pq)2(acac)); and a rare-earth metal complex, such as... B. Tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: Tb(acac)3(Phen)). These are mainly compounds that emit green phosphorescence and exhibit an emission peak at 500 nm to 600 nm.It should be noted that a metal-organic iridium complex with a pyrimidine framework exhibits notably high reliability and emission efficiency and is therefore particularly preferred. Other examples include (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)) and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm)2(dpm)); organometallic iridium complexes with pyrazine skeletons, 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)) or (Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac)); organometallic iridium complexes with pyridine skeletons, such as... B. Tris(1-phenylisoquinolinato-N,C2')iridium(III) (abbreviation: Ir(piq)3) and Bis(1-phenylisoquinolinato-N,C2')iridium(III)acetylacetonate (abbreviation: Ir(piq)2(acac)); a platinum complex such as e.g.2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphyrinplatin(II) (abbreviation: PtOEP); and rare-earth metal complexes such as tris(1,3-diphenyl-1,3-propanedioneto)(monophenanthroline)europium(III) (abbreviation: Eu(DBM)3(Phen)) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: Eu(TTA)3(Phen)). These are compounds that emit red phosphorescence and exhibit an emission peak at 600 nm to 700 nm. The organometallic iridium complex with a pyrazine skeleton can emit red light with favorable chromaticity (color). Other phosphorescent materials besides those listed above can also be used. Materials listed below can be used as TADF material. A fullerene, a derivative thereof, an acridine derivative such as proflavin, eosin, or the like can be used. A metal-containing porphyrin, such as porphyrin containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), can also be used. Examples of metal-containing porphyrins are a protoporphyrin tin fluoride complex (SnF2(Proto IX)), a mesoporphyrin tin fluoride complex (SnF2(Meso IX)), a hematoporphyrin tin fluoride complex (SnF2(Hemato IX)), a coproporphyrin tetramethyl ester tin fluoride complex (SnF2(Copro III-4Me)), an octaethylporphyrin tin fluoride complex (SnF2(OEP)), an etioporphyrin tin fluoride complex (SnF2(Etio I)) and an octaethylporphyrin platinum chloride complex (PtCl2(OEP)), which are represented below by their structural formulas. Alternatively, a heterocyclic compound containing a π-electron-rich heteroaromatic ring and a π-electron-poor heteroaromatic ring can be used, such as 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), which is represented below by its structural formula. The heterocyclic compound is preferred due to the presence of both the π-electron-rich and π-electron-poor heteroaromatic rings; consequently, its electron transport and hole transport properties are high.It should be noted that a substance in which the π-electron-rich heteroaromatic ring is directly bonded to the π-electron-poor heteroaromatic ring is particularly preferred because the donor property of the π-electron-rich heteroaromatic ring and the acceptor property of the π-electron-poor heteroaromatic ring are both increased and the energy difference between the S1 level and the T1 level becomes small. There is no particular restriction regarding the materials that can be used as the first and second organic compounds, as long as the combination of materials meets the conditions described in embodiment 1. Various load carrier transport materials can be selected. Examples of materials with electron transport properties include heterocyclic compounds with a polyazole skeleton, such as 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) or bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ); a heterocyclic compound with a polyazole skeleton, such as...2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-Biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-Bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-Phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI) or 2-[3-(Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II); a heterocyclic compound with a diazine backbone, such as e.g.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), 4,6-Bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm) or 4,6-Bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II); and a heterocyclic compound with a pyridine skeleton, such as 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoline (abbreviation: 2mDBTBPDBQu-II), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), or 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB). Among the above materials, a heterocyclic compound with a diazine skeleton and a heterocyclic compound with a pyridine skeleton exhibit high reliability and are therefore preferred.In particular, a heterocyclic compound with a diazine framework (pyrimidine framework or pyrazine framework) has a high electron transport property, which contributes to a reduction in the operating voltage. Examples of materials with hole transport properties include compounds with an aromatic amine skeleton, such as...4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-Bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-Bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-Diphenyl-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF) or N-Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF); a compound with a carbazole skeleton, such as...1,3-Bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-Di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-Bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP) or 3,3'-Bis(9-phenyl-9H-carbazole) (abbreviation: PCCP); a compound with a thiophene skeleton, such as... B. 4,4',4"-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) or 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV); and a compound with a furan skeleton, such as 4,4',4"-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) or 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II).Among the above materials, a compound with an aromatic amine skeleton and a compound with a carbazole skeleton are preferred because these compounds are highly reliable and have high hole transport properties, which contributes to a reduction in operating stress. Charge carrier transport materials can be selected from various substances as well as from those listed above. It should be noted that the first and second organic compounds are preferably chosen to have a triplet level (the energy difference between a ground state and a triplet excitation state) higher than the triplet level of the phosphorescent compound. Furthermore, the combination of the first and second organic compounds is preferably selected to form an exciplex that emits light whose wavelength overlaps a wavelength on the lowest-energy side of an absorption band of the phosphorescent compound. Furthermore, the combination of a material with electron transport properties as one of the first and second organic compounds and a material with hole transport properties as the other organic compound is advantageous for forming an exciplex. The transport properties of the light-emitting layer can be easily regulated, and the recombination range can be easily regulated by changing the amount of each of the contained compounds. The ratio of the amount of each of the contained material with hole transport properties to the amount of each of the contained material with electron transport properties can be from 1:9 to 9:1. The light-emitting layer 113 with the structure described above can be formed by co-evaporation using a vacuum evaporation process or an inkjet process, a rotary coating process, a dip coating process or the like, using a solution mixture. It should be noted that, although this embodiment describes a structure in which the first light-emitting layer 113a is formed on the anode side and the second light-emitting layer 113b is formed on the cathode side, the order of the layers can be reversed. In other words, the second light-emitting layer 113b can be formed on the anode side, and the first light-emitting layer 113a can be formed on the cathode side. The second light-emitting layer 113b can be divided into two or more layers, and the divided layers can contain different light-emitting substances. In particular, a structure is preferably used in which the second light-emitting layer 113b is divided into a first phosphorescent layer that emits red light (i.e., light with a peak in the emission spectrum at 580 nm to 680 nm) and a second phosphorescent layer that emits green light (i.e., light with a peak in the emission spectrum at 500 nm to 560 nm), and the first light-emitting layer 113a emits blue light (i.e., light with a peak in the emission spectrum at 400 nm to 480 nm), thereby obtaining white light emission with advantageous color rendering properties.It should be noted that in this case, the first light-emitting layer 113a, the first phosphorescent layer, and the second phosphorescent layer are preferably stacked on top of each other in this order for high durability. Furthermore, the first light-emitting layer 113a is preferably formed on the anode side, which allows for advantageous properties. The other structure and effect of the light-emitting layer 113 are the same as those in embodiment 1. Reference is made to embodiment 1. The electron transport layer 114 is a layer containing a substance with electron transport properties. For example, the electron transport layer 114 can be formed using a metal complex with a quinoline or benzoquinoline skeleton, such as tris(8-quinolinolato)aluminium (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminium (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq2), or bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminium (abbreviation: BAlq), or the like. A metal complex with an oxazole-based or thiazole-based ligand, such as... B. Bis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)2) or Bis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ)2), or the like, can also be used.In addition to the metal complexes, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), or similar substances can also be used. The substances listed here exhibit high electron transport properties and are primarily those with an electron mobility of 10⁻⁶ cm² / Vs or higher. It should be noted that any of the host materials listed above with electron transport properties can be used for the electron transport layer 114. The electron transport layer 114 is not limited to a single layer and can be a layer arrangement of two or more layers, each containing one of the substances listed above. A layer for controlling electron carrier transport can be placed between the electron transport layer and the light-emitting layer. This layer is formed by adding a small amount of a substance with high electron capture properties to the aforementioned materials with high electron transport properties. This layer can regulate the charge carrier balance by slowing down the transport of electron carriers. Such a structure is very effective in preventing problems (e.g., a reduction in the element's lifetime) that occur when electrons pass through the light-emitting layer. An electron injection layer 115 can be arranged in contact with the second electrode 102 between the electron transport layer 114 and the second electrode 102. An alkali metal, an alkaline earth metal, or a compound thereof, such as lithium fluoride (LiF), cesium fluoride (CsF), or calcium fluoride (CaF₂), can be used for the electron injection layer 115. For example, a layer formed using a substance with electron transport properties and containing an alkali metal, an alkaline earth metal, or a compound thereof can be used. It should be noted that a layer formed using a substance with electron transport properties and containing an alkali metal or an alkaline earth metal is preferably used as the electron injection layer 115, thereby efficiently carrying out electron injection from the second electrode 102. For the second electrode 102, one of the metals, alloys, electrically conductive compounds, and mixtures thereof exhibiting a low work function (particularly a work function of 3.8 eV or less) or the like can be used. Specific examples of such a cathode material are elements belonging to groups 1 and 2 of the periodic table, such as alkali metals (e.g., lithium (Li) and cesium (Cs)), magnesium (Mg), calcium (Ca), and strontium (Sr), alloys thereof (e.g., MgAg and AlLi), rare-earth metals, such as europium (Eu) and ytterbium (Yb), and alloys thereof. However, if the electron injection layer is arranged between the second electrode 102 and the electron transport layer, one of various conductive materials, such as... B. Al, Ag, ITO or indium oxide-tin oxide containing silicon or silicon oxide, can be used regardless of the work function.These conductive materials can be deposited using a sputtering process, an inkjet process, a rotational coating process, or the like. One of several processes can be used to form the EL layer 103, regardless of whether it is a dry or wet process. For example, a vacuum evaporation process, an inkjet process, or a rotational coating process can be used. A different manufacturing process can be used for each electrode or each layer. The electrode can be formed using a wet process such as a sol-gel process or a wet process using a paste of a metallic material. Alternatively, the electrode can be formed using a dry process, such as sputtering or vacuum evaporation. In the light-emitting element with the structure described above, current flows as a result of a potential difference between the first electrode 101 and the second electrode 102, and holes and electrons recombine in the light-emitting layer 113, which contains a substance with high light-emitting properties, thus emitting light. This means that a light-emitting region is formed in the light-emitting layer 113. Light emission is extracted to the outside through the first electrode 101 and / or the second electrode 102. Therefore, the first electrode 101 and / or the second electrode 102 are transparent electrodes. It should be noted that the structure of the EL layer 103, which is arranged between the first electrode 101 and the second electrode 102, is not limited to the structure described above. Preferably, a light-emitting region in which holes and electrons recombine is positioned away from the first electrode 101 and the second electrode 102, so that quenching due to the proximity of the light-emitting region and a metal used for electrodes and charge carrier injection layers can be prevented. In order to suppress the energy transfer of an exciton generated in the light-emitting layer, the hole transport layer and the electron transport layer in contact with the light-emitting layer 113, in particular a charge carrier transport layer in contact with a side that is closer to the light-emitting region in the light-emitting layer 113, are preferably formed using a substance that has a larger band gap than the light-emitting substance of the light-emitting layer or the emission center substance contained in the light-emitting layer. A light-emitting element of this embodiment is preferably produced on a substrate of glass, plastic, or the like. Layers can be arranged on top of each other from the side of the first electrode 101 or from the side of the second electrode 102. Although a single light-emitting element can be produced on top of a substrate in a light-emitting device, a plurality of light-emitting elements can also be produced on top of a substrate. When a plurality of light-emitting elements, as described above, are formed on top of a substrate, a lighting device in which elements are divided or a light-emitting passive matrix device can be produced.A light-emitting element can be formed over an electrode electrically connected to, for example, a field-effect transistor (FET) mounted on a substrate of glass, plastic, or the like, thus creating a light-emitting active-matrix device in which the FET controls the operation of the light-emitting element. It should be noted that the structure of the FET is not particularly restricted. Furthermore, the crystallinity of a semiconductor used for the FET is also not particularly restricted; an amorphous semiconductor or a crystalline semiconductor can be used. Additionally, a driver circuit can be implemented in a FET substrate with an n-type FET and a p-type FET, or with either an n-type FET or a p-type FET. It should be noted that this embodiment can be appropriately combined with one of the other embodiments. Next, a type of light-emitting element with a structure in which a plurality of light-emitting units are layered (hereinafter also referred to as a multilayer element) is described with reference to Fig. 1B. In this light-emitting element, a plurality of light-emitting units are provided between a first electrode and a second electrode. A light-emitting unit has a structure similar to that of the EL layer 103 in Fig. 1A. In other words, the light-emitting element in Fig. 1A includes a single light-emitting unit; the light-emitting element in this embodiment includes a plurality of light-emitting units. In Fig. 1B, a first light-emitting unit 511 and a second light-emitting unit 512 are layered between a first electrode 501 and a second electrode 502, and a charge-generating layer 513 is provided between the first light-emitting unit 511 and the second light-emitting unit 512. The first electrode 501 and the second electrode 502 correspond to the first electrode 101 and the second electrode 102, respectively, in Fig. 1A, and the materials specified in the description for Fig. 1A can be used. Furthermore, the first light-emitting unit 511 and the second light-emitting unit 512 can have the same structure or different structures. The charge generation layer 513 contains a composite material of an organic compound and a metal oxide. The composite material used for the hole injection layer 111 in Fig. 1A can be the same as that used for the hole injection layer 111. Preferably, the organic compound should have a hole mobility of 1 × 10⁻⁶ cm² / Vs or higher. It should be noted that any other substance can be used, provided it has a higher hole transport property than electron transport property. Due to its excellent charge carrier injection and transport properties, the composite material can operate at low voltage and low current.It should be noted that if a surface of a light-emitting unit on the anode side is in contact with a charge-generating layer, the charge-generating layer can also serve as a hole transport layer of the light-emitting unit; therefore, a hole transport layer does not necessarily have to be formed in the light-emitting unit. The charge-generating layer 513 can have a multilayer structure consisting of a layer containing the composite material of an organic compound and a metal oxide, and a layer containing another material. For example, a layer containing the composite material of the organic compound and the metal oxide can be combined with a layer containing a compound of a substance selected from substances with electron-donating properties and a compound with high electron-transport properties. Furthermore, a layer containing the composite material of the organic compound and the metal oxide can be combined with a transparent conductive film. The charge-generating layer 513, which is interposed between the first light-emitting unit 511 and the second light-emitting unit 512, can have any structure as long as electrons can be injected into a light-emitting unit on one side and holes can be injected into a light-emitting unit on the other side when a voltage is applied between the first electrode 501 and the second electrode 502. For example, in Fig. 1B, any layer can be used as the charge-generating layer 513 as long as the layer injects electrons into the first light-emitting unit 511 and holes into the second light-emitting unit 512 when a voltage is applied such that the potential of the first electrode is higher than that of the second electrode. The light-emitting element comprising two light-emitting units is described with reference to Fig. 1B; however, the present invention can be applied equally to a light-emitting element in which three or more light-emitting units are layered. When a plurality of light-emitting units, separated by the charge-generating layer, are arranged between a pair of electrodes, as in the light-emitting element of this embodiment, it is possible to provide a light-emitting element capable of emitting light with high luminance while maintaining a low current density and exhibiting a long lifetime. Furthermore, it is possible to obtain a light-emitting device that can be operated at a low voltage and has low power consumption. If the structure of the light-emitting layer 113 described above is applied to at least one of the multitude of units, the number of manufacturing steps of the unit can be reduced; consequently, a multi-colored light-emitting element suitable for practical use can be provided. The structure described above can be combined with any of the structures in this embodiment and the other embodiments. (Version 3) In this embodiment, a light-emitting device is described which includes the light-emitting element described in embodiment 1 or 2. In this embodiment, the light-emitting device, which is manufactured using the light-emitting element described in embodiment 1 or 2, is described with reference to Figures 2A and 2B. It should be noted that Figure 2A is a top view of the light-emitting device and that Figure 2B is a cross-sectional view along lines AB and CD in Figure 2A. This light-emitting device includes a driver circuit section (source line driver circuit) 601, a pixel section 602, and a driver circuit section (gate line driver circuit) 603, which control the light emission of the light-emitting element and are designated by dotted lines. Reference numeral 604 denotes a sealing substrate; 605 a sealing medium; and 607 a space enclosed by the sealing medium 605. It should be noted that a connecting line 608 is a line for transmitting signals input to the source line driver circuit 601 and the gate line driver circuit 603, and for receiving a video signal, a clock signal, a start signal, a reset signal, and the like from an FPC (flexible printed circuit) 609, which serves as an external input terminal. Although only the FPC is shown here, a printed circuit board (PWB) may be attached to the FPC. The light-emitting device in this description includes, in its category, not only the light-emitting device itself, but also the light-emitting device equipped with the FPC or the PWB. Next, a cross-sectional structure is described with reference to Fig. 2B. The driver circuit section and the pixel section are formed on an element substrate 610. The source line driver circuit 601, which is a driver circuit section, and one of the pixels in the pixel section 602 are shown here. In the source line driver circuit 601, a CMOS circuit is formed in which an n-channel FET 623 and a p-channel FET 624 are combined. Additionally, the driver circuit can be configured with one of various circuits, such as a CMOS circuit, a PMOS circuit, and an NMOS circuit. Although this embodiment describes a driver-integrated type in which a driver circuit is formed on top of a substrate, an embodiment of the present invention is not limited to this type, and the driver circuit can be formed outside the substrate. The pixel section 602 comprises a plurality of pixels, each containing a switching FET 611, a current-controlling FET 612, and a first electrode 613 electrically connected to a drain of the current-controlling FET 612. An insulator 614 is provided to cover end sections of the first electrode 613. In this embodiment, the insulator 614 is formed using a positive photosensitive acrylic resin film. The insulator 614 preferably has a curved surface with a curvature at either an upper end section or a lower end section. For example, if a positive photosensitive acrylic resin is used for the insulator 614, only the upper end section of the insulator 614 has a surface with a radius of curvature (0.2 µm to 3 µm). The insulator 614 can be made of either a negative photosensitive resin or a positive photosensitive resin. An EL layer 616 and a second electrode 617 are formed over the first electrode 613. The material for the first electrode 613, which serves as the anode, is preferably one with a high work function. For example, a single-layer film of an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% to 20 wt% zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a zinc film, a platinum film, or the like; a layer arrangement comprising a titanium nitride film and a film containing aluminum as the main component; a layer arrangement comprising three layers of a titanium nitride film, a film containing aluminum as the main component, and a titanium nitride film; or the like may be used. The multi-layer structure enables low conduction resistance, good ohmic contact, and anode function. The EL layer 616 is formed by one of several processes, such as an evaporation process using an evaporation mask, an inkjet process, and a rotational coating process. The EL layer 616 has a structure similar to that described in embodiment 1 or 2. Any low molecular weight or high molecular weight compound (including oligomers and dendrimers) can be used as an additional material incorporated into the EL layer 616. The material for the second electrode 617, which is formed above the EL layer 616 and serves as the cathode, is preferably a material with a low work function (e.g., Al, Mg, Li, Ca, or an alloy or compound thereof, such as MgAg, Mgln, or AlLi). When the light generated in the EL layer 616 passes through the second electrode 617, a layer arrangement consisting of a thin metal film and a transparent conductive film (e.g., ITO, indium oxide containing 2 wt.% to 20 wt.% zinc oxide, indium tin oxide containing silicon, or zinc oxide (ZnO)) is preferably used for the second electrode 617. It should be noted that the light-emitting element is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting element has the structure described in embodiment 1 or 2. In the light-emitting device of this embodiment, the pixel section comprising a plurality of light-emitting elements can include both the light-emitting element described in embodiment 1 or 2 and a light-emitting element with a different structure. The sealing substrate 604 is attached to the element substrate 610 by means of the sealing agent 605, such that the light-emitting element 618 is arranged in the space 607, which is surrounded by the element substrate 610, the sealing substrate 604, and the sealing agent 605. The space 607 can be filled with a filler, an inert gas (such as nitrogen or argon), or the sealing agent 605. Preferably, the sealing substrate is provided with a recessed portion, and the desiccant 625 is arranged in this recessed portion, thereby suppressing deterioration due to moisture. An epoxy-based resin or a glass frit is preferably used for the sealant 605. Preferably, such a material is as impermeable as possible to moisture or oxygen. The sealant substrate 604 can be a glass substrate, a quartz substrate, or a plastic substrate made of fiber-reinforced plastic (FRP), polyvinyl fluoride (PVF), polyester, acrylic, or the like. As described above, the light-emitting device which includes the light-emitting element described in embodiment 1 or 2 can be obtained. Fig. 3A and Fig. 3B each represent an example of a light-emitting device in which full-color display is achieved by forming a white light-emitting element and providing a color layer (a color filter) and the like. Fig. 3A 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, first electrodes 1024W, 1024R, 1024G and 1024B of light-emitting elements, a partition 1025, an EL layer 1028, a second electrode 1029 of the light-emitting elements, a sealing substrate 1031, a sealing agent 1032 and the like. In Fig. 3A, color layers (a red color layer 1034R, a green color layer 1034G, and a blue color layer 1034B) are provided on a transparent base material 1033. A black layer (a black matrix) 1035 may also be provided. The transparent base material 1033, which is provided with the color layers and the black layer, is positioned and attached to the substrate 1001. It should be noted that the color layers and the black layer are covered with a covering layer 1036. In Fig. 3A, the light emitted by one part of the light-emitting layer does not pass through the color layers, while the light emitted by the other part of the light-emitting layer does pass through the color layers. Since the light that does not pass through the color layers is white, and the light that does pass through one of the color layers is red, blue, or green, an image can be displayed using pixels of the four colors. Fig. 3B shows 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 between the gate insulating film 1003 and the first intermediate layer insulating film 1020. As shown in Fig. 3B, the color layers can be arranged between the substrate 1001 and the sealing substrate 1031. The light-emitting device described above has a structure in which light is extracted from the side of the substrate 1001 on which the FETs are formed (a bottom-emission structure), but it can also have a structure in which light is extracted from the side of the sealing substrate 1031 (a top-emission structure). Fig. 4 is a cross-sectional view of a light-emitting device with a top-emission structure. In this case, a substrate that does not transmit light can be used as the substrate 1001. The process up to the step of forming a connecting electrode that links the FET and the anode of the light-emitting element is carried out similarly to that of the light-emitting device with a bottom-emission structure. Then, a third intermediate insulating film 1037 is formed such that it covers an electrode 1022. This insulating film can have a flattening function.The third interlayer insulating film 1037 can be formed using a material similar to that of the second interlayer insulating film, or alternatively, it can be formed using one of other materials. The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting elements serve as anodes, but can also function as cathodes. In the case of a light-emitting device with a top-emission structure as shown in Fig. 4, the first electrodes are preferably reflective electrodes. The EL layer 1028 is configured to have a structure similar to that of the EL layer 103 described in embodiment 1 or 2, which allows for white light emission. In the case of a top-emission structure as shown in Fig. 4, the sealing can be carried out 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 black layer (black matrix) 1035, which is positioned between pixels. The color layers (the red color layer 1034R, the green color layer 1034G, and the blue color layer 1034B) and the black layer (black matrix) 1035 can be covered with a coating layer. It should be noted that a translucent substrate is used as the sealing substrate 1031. Although an example is shown here in which full-color display is performed using four colors, namely red, green, blue and white, there is no particular restriction, and full-color display using three colors, namely red, green and blue, can be performed. The light-emitting device in this embodiment is manufactured using the light-emitting element described in embodiment 1 or 2 and can therefore have advantageous properties. Specifically, since the light-emitting element described in embodiment 1 or 2 has a high emission efficiency, the light-emitting device can have reduced power consumption. Furthermore, since the light-emitting element is easily manufactured in large quantities, the light-emitting device can be provided at low cost. Although a light-emitting active matrix device has been described above, a light-emitting passive matrix device is described below. Figures 5A and 5B depict a light-emitting passive matrix device fabricated using the present invention. Figure 5A is a perspective view of the light-emitting device, and Figure 5B is a cross-sectional view along line XY in Figure 5A. In Figures 5A and 5B, an EL layer 955 is provided over a substrate 951 between an electrode 952 and an electrode 956. An end section of the electrode 952 is covered with an insulating layer 953. A separating layer 954 is further arranged over the insulating layer 953. The side walls of the separating layer 954 are chamfered such that the distance between one side wall and the other side wall gradually decreases towards the surface of the substrate.In other words, the cross-section along the short side of the separating layer 954 is trapezoidal, and the lower side (a side oriented in the same direction as the surface direction of the insulating layer 953 and in contact with the insulating layer 953) is shorter than the upper side (a side oriented in the same direction as the surface direction of the insulating layer 953 and not in contact with the insulating layer 953). By providing the separating layer 954 in this way, defects in the light-emitting element due to static electricity or the like can be prevented. The light-emitting passive matrix device also includes the light-emitting element described in embodiment 1 or 2, which has high emission efficiency and can therefore have lower power consumption.Furthermore, since the light-emitting element is easily manufactured in large quantities, the light-emitting device can be provided at low cost. Since many fine light-emitting elements in a matrix in the light-emitting device described above can each be controlled, the light-emitting device can advantageously be used as a display device for showing images. This embodiment can be freely combined with any of the other embodiments. (Version 4) In this embodiment, an example in which the light-emitting element described in embodiment 1 or 2 is used for a lighting device is described with reference to Fig. 6A and Fig. 6B. Fig. 6B is a top view of the lighting device, and Fig. 6A is a cross-sectional view along line ef in Fig. 6B. In the lighting device of this embodiment, a first electrode 401 is formed over a substrate 400, which is a support and has a translucent property. The first electrode 401 corresponds to the first electrode 101 of embodiment 1. When light is extracted through the side of the first electrode 401, the first electrode 401 is formed using a material with a translucent property. A pad 412 for applying a voltage to a second electrode 404 is provided above the substrate 400. An EL layer 403 is formed above the first electrode 401. The structure of the EL layer 403 corresponds, for example, to the structure of the EL layer 103 in embodiment 1 or to the structure in which the light-emitting units 511 and 512 and the charge-generating layer 513 are combined. Reference can be made to the description of embodiment 1 regarding these structures. The second electrode 404 is configured to cover the EL layer 403. The second electrode 404 corresponds to the second electrode 102 of embodiment 1. The second electrode 404 is formed using a material with a high reflectivity when light is extracted through the side of the first electrode 401. The second electrode 404 is connected to the pad 412, thereby applying a voltage to it. As described above, the lighting device described in this embodiment includes a light-emitting element comprising the first electrode 401, the EL layer 403, and the second electrode 404. Since the light-emitting element has a high emission efficiency, the lighting device of this embodiment can have low power consumption. The light-emitting element with the protruding structure is attached to a sealing substrate 407 by means of sealants 405 and 406, and sealing is carried out, thereby completing the lighting device. It is possible to use either the sealant 405 or the sealant 406 alone. Furthermore, the inner sealant 406 (not shown in Fig. 6B) can be mixed with a desiccant, which allows for moisture adsorption, resulting in increased reliability. If portions of pad 412 and the first electrode 401 extend beyond the sealing elements 405 and 406, these extended portions can serve as external input terminals. An IC chip 420, mounted with a converter or the like, can be provided via these external input terminals. Since the lighting device described in this embodiment, as described above, incorporates the light-emitting element described in embodiments 1 or 2 as an EL element, the lighting device can have low power consumption. Furthermore, the light-emitting device can have a low operating voltage. In addition, the light-emitting device can be cost-effective. (Version 5) This embodiment describes examples of electronic devices, each incorporating the light-emitting element described in embodiment 1 or 2. The light-emitting element described in embodiment 1 or 2 exhibits high emission efficiency and reduced power consumption. As a result, the electronic devices described in this embodiment can each incorporate a light-emitting area with reduced power consumption. The light-emitting element described in embodiment 1 or 2 comprises a small number of layers; therefore, the electronic devices can be cost-effective. Examples of the electronic device to which the aforementioned light-emitting element is applied include television sets (also called TVs or television receivers), computer monitors and the like, cameras such as digital cameras and digital video cameras, digital photo frames, mobile phones (also called cell phones or portable telephones), portable gaming consoles, portable information terminals, audio playback devices, and large gaming machines such as pinball machines. Specific examples of these electronic devices are given below. Fig. 7A shows an example of a television set. In this television set, a display section 7103 is installed in a housing 7101. The housing 7101 is also supported by a base 7105. Images can be displayed on the display section 7103, in which the light-emitting elements described in embodiment 1 or 2 are arranged in a matrix. The television can be operated using a control switch on the housing 7101 or a separate remote control 7110. The remote control 7110's control buttons 7109 allow control of television channels and volume, as well as control of images displayed on the display section 7103. The remote control 7110 can also be equipped with a display section 7107 for showing data output by the remote control 7110. It should be noted that the television set is equipped with a receiver, a modem, and the like. The receiver allows for the reception of general television broadcasts. Furthermore, if the display device is connected to a communication network, either wirelessly or via the modem, unidirectional (from a sender to a receiver) or bidirectional (between a sender and a receiver or between receivers) data communication can take place. Fig. 7B1 depicts a computer comprising a main part 7201, a housing 7202, a display section 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, and the like. It should be noted that this computer is manufactured by using light-emitting elements arranged in a matrix, identical to the element described in embodiment 1 or 2, in the display section 7203. The computer in Fig. 7B1 may have a structure as shown in Fig. 7B2. A computer in Fig. 7B2 is provided with a second display section 7210 instead of the keyboard 7204 and the pointing device 7206. The second display section 7210 is a touchscreen, and input can be made by controlling the display for input on the second display section 7210 with a finger or an associated stylus.The second display section 7210 can also display images other than the input display. The display section 7203 can also be a touchscreen. Connecting the two screens by means of a hinge can prevent problems; for example, it can prevent the screens from cracking or being damaged while the computer is stored or being carried. It should be noted that this computer is made by arranging the light-emitting elements described in embodiment 1 or 2 in a matrix in the display section 7203. Fig. 7C shows a portable game console comprising two enclosures, enclosure 7301 and enclosure 7302, connected to each other by means of a hinge 7303, so that the portable game console can be opened or folded. Enclosure 7301 contains a display section 7304, which includes the light-emitting elements described in embodiment 1 or 2 and arranged in a matrix, and enclosure 7302 contains a display section 7305. Additionally, the portable game console in Fig. 7C includes...7C a loudspeaker section 7306, a storage media insertion area 7307, an LED lamp 7308, an input device (an operating button 7309, a connection port 7310, a sensor 7311 (a sensor with a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotational frequency, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electric current, radiation, flow rate, humidity, gradient, oscillation, odor or infrared rays) or a microphone 7312) and the like.Of course, the structure of the portable game console is not limited to the structure described above, as long as the display section, which includes the light-emitting elements described in embodiments 1 and 2 respectively and arranged in a matrix, is used as at least one of display section 7304 and display section 7305, or both, and the structure may include further accessories as required. The portable game console in Fig. 7C has a function to read and display a program or data stored in a storage medium on the display section, and a function to share information with another portable game console via wireless communication. The portable game console in Fig. 7C may have various functions, not being limited to those described above. Fig. 7D shows an example of a mobile phone. The mobile phone is provided with a display section 7402, which is installed in a housing 7401, an operating button 7403, an external connection port 7404, a loudspeaker 7405, a microphone 7406, and the like. It should be noted that the mobile phone includes the display section 7402, which contains the light-emitting elements that have been described in embodiments 1 and 2, respectively, and which are arranged in a matrix. When the display section 7402 of the mobile phone in Fig. 7D is touched with a finger or the like, data can be entered into the mobile phone. In this case, operations such as making calls and writing emails can be carried out by touching the display section 7402 with a finger or the like. There are three main screen modes for the 7402 display section. The first mode is a display mode, primarily for showing images. The second mode is an input mode, primarily for entering data, such as text. The third mode is a combined display and input mode. For example, when making a call or writing an email, a text input mode, primarily used for entering text, is selected for display section 7402, allowing the text shown on the screen to be entered. In this case, a keyboard or number keys are preferably displayed across almost the entire screen of display section 7402. If a detector device containing a sensor for detecting inclination, such as a gyroscope or accelerometer, is provided in the mobile phone, the direction of the mobile phone (whether the mobile phone is held horizontally or vertically, for landscape or portrait orientation) is determined so that the display on the screen of display section 7402 can be switched automatically. The screen modes are switched by touching the display section 7402 or by operating the control knob 7403 on the housing 7401. The screen modes can be switched depending on the type of image displayed on the display section 7402. For example, if the signal of an image displayed on the display section is a data signal about a moving image, the screen mode switches to display mode. If the signal is a text data signal, the screen mode switches to input mode. Furthermore, if no input is made by touching the display section 7402 for a certain period of time in input mode, while a signal detected by an optical sensor in the display section 7402 is being detected, the screen mode can be controlled in such a way that it switches from input mode to display mode. The display section 7402 can function as an image sensor. For example, an image of a palm print, fingerprint, or similar feature can be captured by touching the display section 7402 with the palm or finger, thus enabling personal authentication. Furthermore, an image of a finger vein, palm vein, or similar feature can be captured by providing a backlight or a scanning light source emitting near-infrared light within the display section. It should be noted that the structure described in this embodiment can be appropriately combined with one of the structures described in embodiments 1 to 4. As described above, the scope of application of the light-emitting device, which includes the light-emitting element described in embodiment 1 or 2, is such that the light-emitting device can be applied to electronic devices in various fields. Using the light-emitting element described in embodiment 1 or 2, an electronic device with reduced power consumption can be obtained. Fig. 8 shows an example of a liquid crystal display device in which the light-emitting element described in embodiment 1 or 2 is used for backlighting. The liquid crystal display device in Fig. 8 includes a housing 901, a liquid crystal layer 902, a backlighting unit 903, and a housing 904. The liquid crystal layer 902 is connected to a driver IC 905. The light-emitting element described in embodiment 1 or 2 is used for the backlighting unit 903, which is supplied with current via a terminal 906. The light-emitting element described in embodiment 1 or 2 is used for the backlighting of the liquid crystal display device; therefore, the backlighting can have reduced power consumption. The use of the light-emitting element described in embodiment 2 additionally enables the manufacture of a planar emission illumination device and furthermore, the manufacture of a large-area planar emission illumination device; therefore, the backlighting can be a large-area backlighting, and the liquid crystal display device can also be a large-area device. Furthermore, the light-emitting device using the light-emitting element described in embodiment 2 can be thinner than a conventional one; accordingly, the display device can also be thinner. Fig. 9 shows an example in which the light-emitting element described in embodiment 1 or 2 is used for a table lamp, which is a lighting device. The table lamp in Fig. 9 includes a housing 2001 and a light source 2002. The lighting device described in embodiment 4 is used for the light source 2002. Fig. 10 shows an example in which the light-emitting element described in embodiment 1 or 2 is used for an interior lighting device 3001. Since the light-emitting element described in embodiment 1 or 2 has reduced power consumption, a lighting device with reduced power consumption can be obtained. Furthermore, since the light-emitting element described in embodiment 1 or 2 can have a large area, it can be used for a large-area lighting device. Finally, since the light-emitting element described in embodiment 1 or 2 is thin, it can be used for a lighting device with reduced thickness. The light-emitting element described in embodiment 1 or 2 can also be used for a car windshield or car dashboard. Fig. 11 shows an embodiment in which the light-emitting element described in embodiment 2 is used for a car windshield and a car dashboard. Display areas 5000 to 5005 each contain the light-emitting element described in embodiment 1 or 2. Display area 5000 and display area 5001 are provided in the car windshield, in which the light-emitting elements described in embodiment 1 or 2 are installed. The light-emitting element described in embodiment 1 or 2 can be formed into a so-called transparent display device through which the opposite side can be seen, by including a first electrode and a second electrode formed by electrodes with translucent properties. Such a transparent display device does not impair visibility and can therefore be provided in the car windshield. It should be noted that if a transistor is provided for operation or the like, a transistor with a translucent property, such as...preferably an organic transistor in which an organic semiconductor material is used, or a transistor in which an oxide semiconductor is used. A display area 5002 is provided in a pillar area, in which the light-emitting elements described in embodiment 1 or 2 are installed. The display area 5002 can compensate for the view obstructed by the pillar area by displaying an image captured by an imaging unit in the vehicle body. Similarly, the display area 5003 in the instrument panel can compensate for the view obstructed by the vehicle body by displaying an image captured by an imaging unit outside the vehicle body, thus eliminating blind spots and increasing safety. By displaying an image that compensates for the area a driver cannot see, the driver can easily and conveniently confirm safety. Display areas 5004 and 5005 can show various types of information, such as navigation data, a speedometer, a tachometer, an odometer, a fuel gauge, a gear shift indicator, and air conditioning settings. The content or layout of the display can be changed by the user as needed. It should be noted that such information can also be displayed by display areas 5000 to 5003. Display areas 5000 to 5005 can also be used as backlighting devices. The light-emitting element described in embodiment 1 or 2 can have high emission efficiency and low power consumption. Therefore, the load on a battery is low, even when many large screens, such as display areas 5000 to 5005, are provided, resulting in convenient use. For this reason, the light-emitting device and the lighting device, each incorporating the light-emitting element described in embodiment 1 or 2, can be used as needed as a light-emitting device and a lighting device in the vehicle, respectively. Figures 12A and 12B show an example of a foldable tablet computer. The tablet computer is shown open in Figure 12A and includes a housing 9630, a display section 9631a, a display section 9631b, a button 9034 for switching the display mode, a power switch 9035, a button 9036 for switching the power-saving mode, a clip 9033, and an operating button 9038. It should be noted that in the tablet computer, the display section 9631a and / or the display section 9631b are designed using a light-emitting device that includes the light-emitting element described in embodiment 1 or 2. Part of the display section 9631a can be a touchscreen area 9632a, and data can be entered when a displayed control button 9637 is touched. Although a structure in which half of the display section 9631a has only a display function and the other half has a touchscreen function is shown as an example, the structure of the display section 9631a is not limited to this. The entire area of ​​the display section 9631a can have a touchscreen function. For example, the entire area of ​​the display section 9631a can display keyboard buttons and function as a touchscreen, while the display section 9631b can be used as a display screen. As with display section 9631a, part of display section 9631b can be a touchscreen area 9632b. When a switch button 9639 for showing / hiding a keyboard on the touchscreen is touched with a finger, a stylus, or the like, the keyboard can be displayed on display section 9631b. Touch-sensitive input can be performed simultaneously on touchscreen areas 9632a and 9632b. Button 9034, used to switch the display mode, allows, for example, switching between portrait and landscape orientation and between monochrome and color display. Button 9036, used to switch the power-saving mode, optimizes the display brightness according to the amount of ambient light detected by an optical sensor in the tablet. In addition to the optical sensor, the tablet may also include another detection device, such as an orientation sensor (e.g., a gyroscope or accelerometer). Although display section 9631a and display section 9631b in Fig. 12A have the same display area, an embodiment of the present invention is not limited to this example. Display section 9631a and display section 9631b may have different areas or different display qualities. For example, one of them may be a display field capable of showing images with a higher resolution than the others. In Fig. 12B, the tablet computer is folded and includes the housing 9630, a solar cell 9633, a charge and discharge control circuit 9634, a battery 9635, and a DC-DC converter 9636. It should be noted that Fig. 12B is an example in which the charge and discharge control circuit 9634 includes the battery 9635 and the DC-DC converter 9636. Since the tablet computer is foldable, the housing 9630 can be closed when the tablet computer is not in use. Consequently, the display sections 9631a and 9631b can be protected, thus providing a tablet computer with high durability and reliability for long-term use. The tablet computer in Fig. 12A and Fig. 12B may also have a function for displaying various types of data (e.g., a still image, a moving image, and a text image), a function for displaying a calendar, date, time, or the like on the display section, a touch-sensitive input function for operating or editing data displayed on the display section by means of touch-sensitive input, a function for controlling processing by various types of software (programs), and the like. The solar cell 9633, which is attached to the surface of the tablet computer, supplies electrical current to a touchscreen, a display section, an image signal processor, and the like. It should be noted that the solar cell 9633 is preferably arranged on one or two surfaces of the housing 9630, thereby efficiently charging the battery 9635. The structure and operation of the charging and discharging control circuit 9634 in Fig. 12B are described with reference to a block diagram in Fig. 12C. Fig. 12C shows the solar cell 9633, the battery 9635, the DC-DC converter 9636, a converter 9638, switches SW1 to SW3, and the display section 9631. The battery 9635, the DC-DC converter 9636, the converter 9638, and the switches SW1 to SW3 correspond to the charging and discharging control circuit 9634 in Fig. 12B. First, an example of operation is described in the case where current is generated by solar cell 9633 using external light. The voltage of the current generated by the solar cell is increased or decreased by DC-DC converter 9636 so that the current has a voltage sufficient to charge battery 9635. Subsequently, when current from battery 9635, which is being charged by solar cell 9633, is used to operate display section 9631, switch SW1 is opened, and the voltage of the current is increased or decreased by converter 9638 to achieve the voltage required for display section 9631. Furthermore, when no display is being performed on display section 9631, switch SW1 is closed, and switch SW2 is opened, allowing battery 9635 to be charged. Although the solar cell 9633 is described as an example of a power generating device, there is no specific restriction regarding the power generating device, and the battery 9635 can be charged by another power generating device, such as a piezoelectric element or a thermoelectric converter element (Peltier element). The battery 9635 can be charged by a contactless power transfer module capable of wireless (contactless) transmission and reception of power, or by another charging device used in combination, and the power generating device is not necessarily provided. An embodiment of the present invention is not limited to the tablet computer with the shape shown in Figs. 12A to 12C, as long as the display section 9631 is included. [Example 1] This example describes a light-emitting element (a light-emitting element 1) of an embodiment of the present invention. It should be noted that the light-emitting element 1 comprised the light-emitting layer 113, which included a fluorescent layer (the first light-emitting layer 113a) and a phosphorescent layer (the second light-emitting layer 113b) in contact with each other. The phosphorescent layer (the second light-emitting layer 113b) was formed from a layer arrangement of a first phosphorescent layer (of the second light-emitting layer 113b)-1, which emits red phosphorescence, and a second phosphorescent layer (of the second light-emitting layer 113b)-2, which emits green phosphorescence. Structural formulas of organic compounds used for the light-emitting element 1 are shown below. A method for producing the light-emitting element 1 of this example is described below. (Method for producing the light-emitting element 1) First, a film of indium tin oxide containing silicon oxide (ITSO) was formed over a glass substrate using a sputtering process, thus creating the first electrode 101. The thickness was 110 nm and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 serves as the anode of the light-emitting element. Next, in the pretreatment for the formation of the light-emitting element above the substrate, a surface of the substrate was washed with water and baked at 200 °C for one hour, and then a UV ozone treatment was carried out for 370 seconds. The substrate was then transferred to a vacuum evaporation device in which the pressure was reduced to approximately 10-4 Pa and heated in a vacuum at 170 °C in a heating chamber of the vacuum evaporation device for 30 minutes, and then the substrate was cooled for about 30 minutes. The substrate, equipped with the first electrode 101, was then mounted on a substrate holder in the vacuum evaporation apparatus so that the surface on which the first electrode 101 was formed faced downwards. The pressure in the vacuum evaporation apparatus was reduced to approximately 10⁻⁴ Pa. Subsequently, 4,4',4"-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), represented by structural formula (i), and molybdenum(VI) oxide were deposited on the first electrode 101 by co-evaporation using a resistance heating process, thus forming the hole injection layer 111. The thickness was set to 40 nm, and the weight ratio of DBT3P-II to molybdenum oxide was adjusted to 4:2 (= DBT3P-II:molybdenum oxide).It should be noted that the co-evaporation process refers to an evaporation process in which evaporation from a multitude of sources is carried out simultaneously in a treatment chamber. Next, 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), represented by structural formula (ii), was deposited on the hole injection layer 111 in a thickness of 20 nm, so that the hole transport layer 112 was formed. On the hole transport layer 112, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), represented by structural formula (iii), and N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-diamine (abbreviation: 1.6mMemFLPAPrn), represented by structural formula (iv), were deposited by co-evaporation to a thickness of 10 nm, so that the fluorescent layer (the first light-emitting layer 113a) was formed such that the weight ratio of cgDBCzPA to 1.6mMemFLPAPrn was 1:0.04 (= cgDBCzPA: 1.6mMemFLPAPrn). was. Then 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), represented by structural formula (v), N-(1,1'-Biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF), represented by structural formula (vi), and (Dipivaloylmethanato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), represented by the structural formula (vii), was deposited by co-evaporation to a thickness of 5 nm, such that the first phosphorescent layer (the second light-emitting layer 113b)-1 was formed such that the weight ratio of 2mDBTBPDBq-II to PCBBiF and [Ir(tppr)2(dpm)] was 0.6:0.4:0.05 (= 2mDBTBPDBq-II: PCBBiF: [Ir(tppr)2(dpm)]), and then 2mDBTBPDBq-II, PCBBiF and Bis[2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4-pentanedionato-κ20,0')iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), which is represented by the structural formula (viii), is deposited by co-evaporation to a thickness of 20 nm, such that the second phosphorescent layer (the second light-emitting layer 113b)-2 is formed such that the weight ratio of 2mDBTBPDBq-II to PCBBiF and [Ir(tBuppm)2(acac)] is 0.8:0.2:0.05 (= 2mDBTBPDBq-II: PCBBiF: [Ir(tBuppm)2(acac)]). In this way, the phosphorescent layer (the second light-emitting layer 113b) was formed. It should be noted that 2mDBTBPDBq-II and PCBBiF form an exciplex in the phosphorescent layer (the second light-emitting layer 113b). In particular, the photoluminescence wavelength of a co-evaporation film of 2mDBTBPDBq-II and PCBBiF (i.e., the emission wavelength of the exciplex) is approximately 515 nm. This emission wavelength overlaps absorption bands on the longest wavelength sides of [Ir(tppr)2(dpm)] and [Ir(tBuppm)2(acac)], so the energy transfer efficiency is high. The singlet excitation energy of cgDBCzPA, a host material in the fluorescent layer, is higher than that of 1.6 mMemFLPAPrn, a fluorescent substance. Furthermore, the triplet excitation energy of cgDBCzPA is lower than that of 1.6 mMemFLPAPrn. Therefore, singlet exciton regeneration coupled with triplet-triplet annihilation and light emission are readily obtained in the fluorescent layer (the first light-emitting layer 113a). Indeed, the occurrence of delayed fluorescence was observed in the structure described above. Subsequently, 2mDBTBPDBq-II was deposited on the phosphor layer (the second light-emitting layer 113b) in a thickness of 10 nm, and bathophene anthroline (abbreviation: BPhen), represented by the structural formula (ix), was deposited in a thickness of 15 nm, so that the electron transport layer 114 was formed. After forming the electron transport layer 114, lithium fluoride (LiF) was deposited by evaporation to a thickness of 1 nm, forming the electron injection layer 115. Finally, aluminum was deposited by evaporation to a thickness of 200 nm to form the second electrode 102, which serves as the cathode. The light-emitting element 1 of this example was fabricated by the steps described above. It should be noted that in all the preceding evaporation steps, the evaporation was carried out by a resistance heating process. Inside a glovebox under a nitrogen atmosphere, the light-emitting element 1 was sealed using a glass substrate to prevent exposure to air (specifically, a sealant was applied to an outer edge of the element, and at the time of sealing, it first underwent UV treatment, followed by a heat treatment at 80 °C for 1 hour). The reliability of the light-emitting element 1 was then measured. It should be noted that the measurement was performed at room temperature (in an atmosphere maintained at 25 °C). Fig. 13 shows current density-luminance properties of the light-emitting element 1. Fig. 14 shows luminance-current efficiency properties of the light-emitting element 1. Fig. 15 shows voltage-luminance properties of the light-emitting element 1. Fig. 16 shows luminance-external quantum efficiency properties of the light-emitting element 1. Fig. 17 shows an emission spectrum of the light-emitting element 1. Although light-emitting element 1 did not contain an intermediate layer, it exhibited a current efficiency of approximately 30 cd / A at about 1000 cd / m² and an external quantum efficiency of approximately 13%, as can be seen from its properties. This indicates that light-emitting element 1 had a high emission efficiency. Furthermore, the operating voltage of light-emitting element 1 was low, greater than or equal to 3 V and less than 4 V. Furthermore, the emission spectrum shows that red light emission originating from [Ir(tppr)2(dpm)], green light emission originating from [Ir(tBuppm)2(acac)], and blue light emission originating from 1.6 mMemFLPAPrn were observed. This indicates that sufficient light emission was obtained from both the fluorescent layer (the first light-emitting layer 113a) and the phosphor layer (the second light-emitting layer 113b). In addition, light-emitting element 1 exhibited a correlated color temperature of 3130 K at approximately 1000 cd / m² and a general color rendering index of 92, meaning that light-emitting element 1 had a sufficient color temperature for illumination and excellent color rendering properties. Fig. 18 shows the results of a reliability test performed on the light-emitting element 1. In the reliability test, the light-emitting element 1 was operated under conditions where the initial luminance was 5000 cd / m² and the current density was constant. Fig. 18 shows a change in normalized luminance with an initial luminance of 100%. The results show that the light-emitting element 1 maintained 94% of the initial luminance even after 62 hours of operation, and that the light-emitting element 1 exhibited a low decrease in luminance over time and high reliability. The singlet excitation levels (S1 levels) of cgDBCzPA and 1.6mMemFLPArn used for light-emitting element 1 were estimated to be 2.95 eV and 2.68 eV respectively due to absorption edges of the Co evaporation film. Table 1 shows measurement results of the triplet levels (T1 levels) of 2mDBTBPDBq-II, PCBBiF, cgDBCzPA, and 1.6mMemFLPAPrn, which were used in this example for light-emitting element 1. The T1 levels were determined by measuring the emission of phosphorescence from the substances. For the measurement, each substance was irradiated with excitation light at a wavelength of 325 nm, and the measurement temperature was 10 K. When measuring an energy level, a calculation using an absorption wavelength is more accurate than a calculation using an emission wavelength. However, the absorption of the T1 level is very low and difficult to measure; therefore, a peak wavelength located on the shortest wavelength side of a phosphorescence spectrum was considered the T1 level. For this reason, some errors may be present in the measured values.It should be noted that, since intersystem crossing is hardly observed in cgDBCzPA and 1.6mMemFLPARN, Tris(2-phenylpyridinato)iridium (abbreviation: Ir(ppy)3) was added as a sensitizer (i.e., co-evaporated), resulting in observed phosphorescence. Table 1. 2mDBTBPDBq-II5152,41 PCBBiF5092.44 cgDBCzPA7211,72 1,6mMemFLPAPrn6751,84 The foregoing results indicate that in the fluorescent layer of light-emitting element 1, the singlet excitation level of cgDBCzPA, which was the host material, was higher than that of 1.6mMemFLPAPrn, which was the fluorescent substance, and that the triplet excitation level of cgDBCzPA was lower than that of 1.6mMemFLPAPrn; therefore, the fluorescent layer (the first light-emitting layer 113a) had a structure in which regeneration of a singlet exciton coupled with triplet-triplet annihilation and light emission were readily obtained. The results also indicate that the triplet excitation level of cgDBCzPA, which was the host material in the fluorescent layer, was lower than that of a first organic compound (2mDBTBPDBq-II) and a second organic compound (PCBBiF) in the phosphor layer. In such a structure, many triplet excitons generated in the phosphor layer generally diffuse into the fluorescent layer, and non-radiative decay occurs. However, in the case of the light-emitting element 1 of this example, the first and second organic compounds formed an exciplex; therefore, triplet excitons generated in the phosphor layer barely diffused into the fluorescent layer. One reason is likely as follows: Energy transfer from one exciplex to another is unlikely to occur because the exciplexes do not possess ground states.Consequently, the light-emitting element 1 exhibited significant properties: light emission from both the fluorescence layer and the phosphorescence layer, as well as high efficiency. As described above, the light-emitting element 1 of an embodiment of the present invention exhibited highly well-balanced, advantageous properties and could be produced easily and cost-effectively. The results described above were attributed to the following: Diffusion of excitons was suppressed and non-radiative decay of the triplet excitation energy was reduced by using the exciplex as the energy donor of the phosphor layer, and the emission efficiency was increased as a result of the occurrence of delayed fluorescence due to triplet-triplet annihilation in the host material in the fluorescence layer. [Example 2] This example describes methods for producing a light-emitting element 2 and a light-emitting element 3 of embodiments of the present invention and their properties. Structural formulas of organic compounds used for the light-emitting element 2 and the light-emitting element 3 are shown below. (Method for producing the light-emitting element 2) A film of indium tin oxide containing silicon oxide (ITSO) with a thickness of 110 nm was formed over a glass substrate by a sputtering process, thus forming the first electrode 101. The electrode area was 2 mm × 2 mm. Next, in the pretreatment for the production of the light-emitting element above the substrate, a surface of the substrate was washed with water and baked at 200 °C for one hour, and then a UV ozone treatment was carried out for 370 seconds. The substrate was then transferred to a vacuum evaporation device in which the pressure had been reduced to approximately 10-4 Pa, and baked in a vacuum at 170 °C in a heating chamber of the vacuum evaporation device for 30 minutes, and then the substrate was cooled over a period of about 30 minutes. The substrate, equipped with the first electrode 101, was then mounted on a substrate holder in the vacuum evaporation apparatus so that the surface on which the first electrode 101 had been formed was facing downwards. The pressure in the vacuum evaporation apparatus was reduced to approximately 10⁻⁴ Pa. Subsequently, 4,4',4"-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), represented by structural formula (i), and molybdenum(VI) oxide were deposited on the first electrode 101 by co-evaporation using a resistance heating process, thus forming the hole injection layer 111. The thickness was set to 30 nm, and the weight ratio of DBT3P-II to molybdenum oxide was adjusted to 2:1 (= DBT3P-II:molybdenum oxide). Next, 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), represented by structural formula (ii), was deposited on the hole injection layer 111 in a thickness of 20 nm, so that the hole transport layer 112 was formed. On the hole transport layer 112, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), represented by structural formula (iii), and N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-diamine (abbreviation: 1.6mMemFLPAPrn), represented by structural formula (iv), were deposited by co-evaporation to a thickness of 10 nm, so that the first light-emitting layer 113a, which was a fluorescent layer, was formed such that the weight ratio of cgDBCzPA to 1.6mMemFLPAPrn was 1:0.02 (= cgDBCzPA: 1.6mMemFLPAPrn). Then, 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), represented by structural formula (v), N-(1,1'-Biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF), represented by structural formula (vi), and Bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC} (2,4-pentanedionato-κ2O,O')iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(acac)]), which is represented by the structural formula (x), was deposited by co-evaporation to a thickness of 5 nm, such that the first phosphorescent layer (the second light-emitting layer 113b)-1 was formed such that the weight ratio of 2mDBTBPDBq-II to PCBBiF and [Ir(dmdppr-dmp)2(acac)] was 0.5:0.5:0.05 (= 2mDBTBPDBq-II: PCBBiF: [Ir(dmdppr-dmp)2(acac)]), and then 2mDBTBPDBq-II, PCBBiF and Bis[2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4-pentanedionato-κ2O,O')iridium(III)) (abbreviation: [Ir(tBuppm)2(acac)]), which is represented by the structural formula (viii), is deposited by co-evaporation to a thickness of 20 nm, such that the second phosphorescent layer (the second light-emitting layer 113b)-2 is formed such that the weight ratio of 2mDBTBPDBq-II to PCBBiF and [Ir(tBuppm)2(acac)] is 0.8:0.2:0.05 (= 2mDBTBPDBq-II: PCBBiF: [Ir(tBuppm)2(acac)]). In this way, the second light-emitting layer 113b, which was the fluorescent layer, was formed. It should be noted that 2mDBTBPDBq-II and PCBBiF form an exciplex in the phosphor layer. This emission wavelength overlaps absorption bands on the longest wavelength sides of [Ir(dmdpprdmp)2(acac)] and [Ir(tBuppm)2(acac)], resulting in high energy transfer efficiency. The singlet excitation energy of cgDBCzPA, a host material in the fluorescent layer (the first light-emitting layer 113a), is higher than the singlet excitation energy of 1.6 mMemFLPARN, a fluorescent substance. Furthermore, the triplet excitation energy from cgDBCzPA is lower than the triplet excitation energy of 1.6 mMemFLPARN. Therefore, in the phosphorescent layer (the first light-emitting layer 113a), singlet exciton regeneration coupled with triplet-triplet annihilation and light emission are readily obtained. Subsequently, 2mDBTBPDBq-II was deposited on the second light-emitting layer 113b, which was the phosphor layer, in a thickness of 10 nm, and bathophene anthroline (abbreviation: BPhen), which is represented by the structural formula (ix), was deposited in a thickness of 15 nm, so that the electron transport layer 114 was formed. After forming the electron transport layer 114, lithium fluoride (LiF) was deposited by evaporation to a thickness of 1 nm, forming the electron injection layer 115. Finally, aluminum was deposited by evaporation to a thickness of 200 nm to form the second electrode 102, which serves as the cathode. The light-emitting element 2 of this example was fabricated by the steps described above. It should be noted that in all the preceding evaporation steps, the evaporation was carried out by a resistance heating process. (Method for producing the light-emitting element 3) Light-emitting element 3 was prepared in a similar manner to light-emitting element 2, except that the weight ratio of 2mDBTBPDBq-II to PCBBiF and [Ir(dmdpprdmp)2(acac)] used to form the first phosphor layer (of the second light-emitting layer 113b)-1 was adjusted to 0.2:0.8:0.05 for light-emitting element 2, and the weight ratio of 2mDBTBPDBq-II to PCBBiF and [Ir(tBuppm)2(acac)] used to form the second phosphor layer (of the second light-emitting layer 113b)-2 was adjusted to 0.9:0.1:0.05 for light-emitting element 2. In a glovebox under a nitrogen atmosphere, light-emitting element 2 and light-emitting element 3 were each sealed using a glass substrate to prevent exposure to air (specifically, a sealant was applied to an outer edge of the element, and at the time of sealing, a UV treatment was first performed, followed by a heat treatment at 80 °C for 1 hour). The properties of the light-emitting elements were then measured. It should be noted that the measurement was performed with an integrating sphere at room temperature (in the atmosphere maintained at 25 °C). Table 2 shows the property values ​​at a current density of 2.5 mA / cm³. light-emitting element 23.047100.0142863614 light-emitting element 33.029500.0083884518 Although light-emitting elements 2 and 3 lacked a special outcoupling structure, they exhibited high external quantum efficiency and current efficiency. Furthermore, the voltage was as low as 3V compared to a tandem light-emitting element. Fig. 19A shows an emission spectrum of light-emitting element 2, and Fig. 19B shows an emission spectrum of light-emitting element 3. As can be seen from the emission spectra, red light emission originating from [Ir(dmdppr-dmp)2(acac)], green light emission originating from [Ir(tBuppm)2(acac)], and blue light emission originating from 1.6mMemFLPAPrn were observed. This indicates that sufficient light emission was obtained from both the first light-emitting layer 113a, which was the fluorescent layer, and the second light-emitting layer 113b, which was the phosphor layer. Furthermore, each of the light-emitting elements had a general color rendering index (Ra) of 85 or higher, meaning that each light-emitting element had favorable color rendering properties, and exhibited low Δuv; consequently, the light-emitting elements are suitable for illumination. Additionally, light-emitting element 2 had a color temperature of 4710 K, corresponding to daylight white, and light-emitting element 3 had a color temperature of 2950 K, corresponding to incandescent white. This indicates that light-emitting elements 2 and 3 possess the properties that meet the specifications. The only difference between light-emitting element 2 and light-emitting element 3 lies in the mixing ratio of the substances used to form the second light-emitting layer 113b. In other words, this example demonstrates that white light emission could be obtained over a wide color temperature range from 2950 K to 4710 K by regulating the mixing ratio of the substances, a simple procedure. It should be noted that a color temperature of 2950 K or lower, or 4710 K or higher, can be achieved by adjusting the mixing ratio. Furthermore, it is a significant feature that light emission was maintained over this wide color temperature range without a substantial reduction in efficiency. This example describes the case of white light emission because the light-emitting elements were each produced emitting light from three colors: blue, green, and red.When a light-emitting element is manufactured that emits light of another color, the mixing ratio of colors of a light emission can be controlled, and a desired emission color can be easily obtained by regulating the mixing ratio of substances contained in the light-emitting element. As described above, light-emitting element 2 and light-emitting element 3 exhibited highly balanced, advantageous properties and can be produced easily and inexpensively. The results described above were attributed to the following: exciton diffusion was suppressed and non-radiative decay of the triplet excitation energy was reduced by using the exciplex as the energy donor of the phosphor layer, and the emission efficiency was increased as a result of the delayed fluorescence occurring due to triplet-triplet annihilation in the host material within the fluorescence layer. [Example 3] This example describes a method for producing a light-emitting element 4 of an embodiment of the present invention and its properties. In the light-emitting element 4, the first light-emitting layer 113a was formed on the cathode side, and the second light-emitting layer 113b was formed on the anode side. Structural formulas of organic compounds used for the light-emitting element 4 are shown below. (Method for producing the light-emitting element 4) A film of indium tin oxide containing silicon oxide (ITSO) with a thickness of 110 nm was formed over a glass substrate by a sputtering process, thus forming the first electrode 101. The electrode area was 2 mm × 2 mm. Next, in the pretreatment for the production of the light-emitting element above the substrate, a surface of the substrate was washed with water and baked at 200 °C for one hour, and then a UV ozone treatment was carried out for 370 seconds. The substrate was then transferred to a vacuum evaporation device in which the pressure had been reduced to approximately 10-4 Pa, and baked in a vacuum at 170 °C in a heating chamber of the vacuum evaporation device for 30 minutes, and then the substrate was cooled over a period of about 30 minutes. The substrate, equipped with the first electrode 101, was then mounted on a substrate holder in the vacuum evaporation apparatus so that the surface on which the first electrode 101 had been formed was facing downwards. The pressure in the vacuum evaporation apparatus was reduced to approximately 10⁻⁴ Pa. Subsequently, 4,4',4"-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), represented by structural formula (i), and molybdenum(VI) oxide were deposited on the first electrode 101 by co-evaporation using a resistance heating process, thus forming the hole injection layer 111. The thickness was set to 40 nm, and the weight ratio of DBT3P-II to molybdenum oxide was adjusted to 4:2 (= DBT3P-II:molybdenum oxide). Next, N-(1,1'-Biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), represented by the structural formula (vi), was deposited on the hole injection layer in a thickness of 20 nm, so that the hole transport layer 112 was formed. On the hole transport layer 112, 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), represented by structural formula (v), PCBBiF, and (Dipivaloylmethanato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), represented by structural formula (vii), were deposited by co-evaporation to a thickness of 20 nm, such that the first phosphorescent layer (the second light-emitting layer 113b)-1 was formed such that the weight ratio of 2mDBTBPDBq-II to PCBBiF and [Ir(tppr)2(dpm)] was 0.2:0.8:0.05 (=2mDBTBPDBq-II: PCBBiF: [Ir(tppr)2(dpm)]) was, and then 2mDBTBPDBq-II, PCBBiF and Bis[2-(6-part-butyl-4-pyrimidinyl-κN3)phenyl-κC](2,4-pentanedionato-κ2O,O')iridium(III)) (abbreviation:.[Ir(tBuppm)2(acac)]), represented by structural formula (viii), was deposited by co-evaporation to a thickness of 5 nm such that the weight ratio of 2mDBTBPDBq-II to PCBBiF and [Ir(tBuppm)2(acac)] was 0.3:0.7:0.05 (= 2mDBTBPDBq-II: PCBBiF: [Ir(tBuppm)2(acac)]). In this way, the second light-emitting layer 113b, which was a phosphorescent layer, was formed. Subsequently, 7-[4-(10-Phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), represented by structural formula (iii), and N,N'-Bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]-pyren-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), represented by structural formula (iv), were deposited by co-evaporation to a thickness of 25 nm, so that the first light-emitting layer 113a, which was a phosphorescent layer, was formed such that the weight ratio of cgDBCzPA to 1,6mMemFLPAPrn was 1:0.04 (=cgDBCzPA: 1,6mMemFLPAPrn).The light-emitting layer 113 was formed by the steps described above. It should be noted that 2mDBTBPDBq-II and PCBBiF form an exciplex in the second light-emitting layer 113b, which is the phosphor layer. This emission wavelength overlaps absorption bands on the longest wavelength sides of [Ir(tppr)2(dpm)] and [Ir(tBuppm)2(acac)], resulting in high energy transfer efficiency. The singlet excitation energy of cgDBCzPA, a host material in the fluorescent layer (the first light-emitting layer 113a), is higher than the singlet excitation energy of 1.6 mMemFLPAPrn, a fluorescent substance. Furthermore, the triplet excitation energy of cgDBCzPA is lower than that of 1.6 mMemFLPAPrn. Therefore, in the phosphorescent layer (the first light-emitting layer 113a), singlet exciton regeneration coupled with triplet-triplet annihilation and light emission are readily obtained. Subsequently, cgDBCzPA was deposited on the first light-emitting layer 113a, which was the fluorescence layer, in a thickness of 10 nm, and bathophenanthroline (abbreviation: BPhen), which is represented by the structural formula (ix), was deposited in a thickness of 15 nm, so that the electron transport layer 114 was formed. After forming the electron transport layer 114, lithium fluoride (LiF) was deposited by evaporation to a thickness of 1 nm, forming the electron injection layer 115. Finally, aluminum was deposited by evaporation to a thickness of 200 nm to form the second electrode 102, which serves as the cathode. The light-emitting element 1 of this example was fabricated by the steps described above. It should be noted that in all the preceding evaporation steps, the evaporation was carried out by a resistance heating process. An element structure of the light-emitting element 4 is shown in Table 3. In a glovebox under a nitrogen atmosphere, the light-emitting element 4 was sealed using a glass substrate to prevent its exposure to air (specifically, a sealant was applied to an outer edge of the element, and at the time of sealing, a UV treatment was first performed, followed by a heat treatment at 80 °C for 1 hour). The properties of the light-emitting element 4 were then measured at a current density of 2.5 mA / cm² and at approximately 1000 cd / m². Table 3 light-emitting element 42.726900.01842911 Although light-emitting element 4 lacked a special outcoupling structure, it exhibited high external quantum yield and current efficiency. Furthermore, light-emitting element 4 operated at a very low voltage of 2.7 V, compared to a tandem light-emitting element. Fig. 20 shows an emission spectrum of the light-emitting element 4. As can be seen from the emission spectrum, red light emission originating from [Ir(tppr)2(dpm)], green light emission originating from [Ir(tBuppm)2(acac)], and blue light emission originating from 1.6mMemFLPAPrn were observed. This indicates that sufficient light emission was obtained from both the first light-emitting layer 113a, which was the fluorescent layer, and the second light-emitting layer 113b, which was the phosphor layer. Furthermore, the light-emitting element 4 had a general color rendering index (Ra) of 84, which means that the light-emitting element 4 had favorable color rendering properties and exhibited only low Δuv; consequently, the light-emitting element 4 is suitable for illumination. In addition, the light-emitting element 4 had a color temperature of 2690 K, which corresponds to an incandescent color. This indicates that the light-emitting element 4 possessed the properties that meet the specifications. As described above, the light-emitting element 4 exhibited well-balanced, advantageous properties and could be produced easily and cost-effectively. The results described above were attributed to the following: exciton diffusion was suppressed and non-radiative decay of the triplet excitation energy was reduced by using the exciplex as the energy donor of the phosphor layer, and the emission efficiency was increased as a result of the delayed fluorescence occurring due to triplet-triplet annihilation in the host material in the fluorescence layer. It was also found that advantageous properties could be maintained even when the layering order in the light-emitting layer 113 was changed. Explanation of reference symbols 101: first electrode, 102: second electrode, 103: EL layer, 111: hole injection layer, 112: hole transport layer, 113: light-emitting layer, 113a: first light-emitting layer, 113b: second light-emitting layer, 114: electron transport layer, 115: electron injection layer, 400: substrate, 401: first electrode, 403: EL layer, 404: second electrode, 405: sealant, 406: sealant, 407: sealant substrate, 412: pad, 420: IC chip, 501: first electrode, 502: second electrode, 511: first light-emitting unit, 512: second light-emitting unit, 513: charge generation layer, 601: driver circuit section (Source line driver circuit), 602: Pixel section, 603: Driver circuit section (Gate line driver circuit), 604: Sealing substrate, 605: Sealant, 607: Sealant, 608: Conductor, 609: Flexible printed circuit (FPC), 610: Element substrate, 611: Switching FET, 612: Current-controlling FET, 613: First electrode, 614: Insulator,616: EL layer, 617: second electrode, 618: light-emitting element, 623: n-channel FET, 624: p-channel FET, 625: desiccant, 901: package, 902: liquid crystal layer, 903: backlight unit, 904: package, 905: driver IC, 906: connector, 951: substrate, 952: electrode, 953: insulating layer, 954: separating layer, 955: EL layer, 956: electrode, 1001: substrate, 1002: base insulating film, 1003: gate insulating film, 1006: gate electrode, 1007: gate electrode, 1008: gate electrode, 1020: first interlayer insulating film 1021: second intermediate layer insulating film, 1022: electrode, 1024W: first electrode of the light-emitting element, 1024R: first electrode of the light-emitting element, 1024G: first electrode of the light-emitting element, 1024B: first electrode of the light-emitting element, 1025: partition, 1028: EL layer, 1029: second electrode of the light-emitting element, 1031: sealing substrate, 1032: sealant, 1033: transparent base material,1034R: red color layer, 1034G: green color layer, 1034B: blue color layer, 1035: black layer (black matrix), 1036: covering layer, 1037: third intermediate layer insulating film, 1040: pixel section, 1041: driver circuit section, 1042: peripheral section, 2001: housing, 2002: light source, 3001: illumination device, 5000: display area, 5001: display area, 5002: display area, 5003: display area, 5004: display area, 5005: display area, 7101: housing, 7103: display section, 7105: foot, 7107: display section, 7109: control button, 7110: remote control, 7201: main body 7202: Housing, 7203: Display section, 7204: Keyboard, 7205: External connection port, 7206: Pointing device, 7210: Second display section, 7301: Housing, 7302: Housing, 7303: Hinge, 7304: Display section, 7305: Display section, 7306: Speaker section, 7307: Storage media insertion area, 7308: LED lamp, 7309: Operating button, 7310: Connection port, 7311: Sensor7401: Housing, 7402: Display section, 7403: Control knob, 7404: External connection port, 7405: Speaker, 7406: Microphone, 7400: Mobile phone, 9033: Clip, 9034: Switch, 9035: Power switch, 9036: Switch, 9038: Control knob, 9630: Housing, 9631: Display section, 9631a: Display section, 9631b: Display section, 9632a: Touchscreen area, 9632b: Touchscreen area, 9633: Solar cell, 9634: Charge and discharge control circuit, 9635: Battery, 9636: DC-DC converter, 9637: Control button, 9638: Converter, and 9639: Button.

Claims

A light-emitting device comprising: an anode; a first light-emitting layer above the anode; a second light-emitting layer above the first light-emitting layer; and a cathode above the second light-emitting layer, wherein the first light-emitting layer comprises a fluorescent substance and a host material, the host material comprising an anthracene framework, wherein the second light-emitting layer comprises a phosphorescent substance, a first organic compound, and a second organic compound, wherein the first organic compound and the second organic compound are configured to form an exciplex, wherein a peak wavelength of light emitted by the first light-emitting layer is shorter than a peak wavelength of light emitted by the second light-emitting layer, wherein the energy value of a peak wavelength of an emission spectrum of the exciplex is a first energy value.where the energy value of a peak wavelength in the absorption band on the side of the lowest energy of the phosphorescent substance is a second energy value, where the difference between the first energy value and the second energy value is less than 0.2 eV, where a triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the fluorescence substance, where the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the first organic compound, and where the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the second organic compound. A light-emitting device comprising: an anode; a first light-emitting layer above the anode; a second light-emitting layer above the first light-emitting layer; and a cathode above the second light-emitting layer, wherein the first light-emitting layer comprises a host material and a fluorescent substance, the fluorescent substance comprising a pyrenediamine compound; wherein the second light-emitting layer comprises a phosphorescent substance, a first organic compound, and a second organic compound, the first organic compound and the second organic compound being configured to form an exciplex; wherein a peak wavelength of light emitted by the first light-emitting layer is shorter than a peak wavelength of light emitted by the second light-emitting layer; and wherein the energy value of a peak wavelength of an emission spectrum of the exciplex is a first energy value.where the energy value of a peak wavelength in the absorption band on the side of the lowest energy of the phosphorescent substance is a second energy value, where the difference between the first energy value and the second energy value is less than 0.2 eV, where a triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the fluorescence substance, where the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the first organic compound, and where the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the second organic compound. A light-emitting device comprising: an anode; a first light-emitting layer above the anode; a second light-emitting layer above the first light-emitting layer; and a cathode above the second light-emitting layer, wherein the first light-emitting layer comprises a fluorescent substance and a host material, the host material comprising an anthracene framework, wherein the second light-emitting layer comprises a first phosphorescent layer and a second phosphorescent layer, wherein the first phosphorescent layer or the second phosphorescent layer comprises a phosphorescent substance, a first organic compound, and a second organic compound, wherein the first organic compound and the second organic compound are configured to form an exciplex, wherein a peak wavelength of light emitted by the first light-emitting layer is shorter than a peak wavelength of light.that is emitted by the first phosphor layer, and is shorter than a peak wavelength of light emitted by the second phosphor layer, wherein the energy value of a peak wavelength of an emission spectrum of the exciplex is a first energy value, wherein the energy value of a peak wavelength in the absorption band on the side of the lowest energy of the phosphor is a second energy value, wherein a difference between the first energy value and the second energy value is less than 0.2 eV, wherein a triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the fluorescence, wherein the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the first organic compound, and wherein the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the second organic compound. Light-emitting device according to claim 1 or 3, wherein the fluorescent substance comprises a pyrenediamine compound. A light-emitting device comprising: an anode; a first light-emitting layer above the anode; a second light-emitting layer above the first light-emitting layer; and a cathode above the second light-emitting layer, wherein the first light-emitting layer comprises a host material and a fluorescent substance, the fluorescent substance comprising a pyrenediamine compound; wherein the second light-emitting layer comprises a first phosphorescent layer and a second phosphorescent layer, the first phosphorescent layer or the second phosphorescent layer comprising a phosphorescent substance, a first organic compound, and a second organic compound, the first organic compound and the second organic compound being configured to form an exciplex; wherein a peak wavelength of light emitted by the first light-emitting layer is shorter than a peak wavelength of light.that is emitted by the first phosphor layer, and is shorter than a peak wavelength of light emitted by the second phosphor layer, wherein the energy value of a peak wavelength of an emission spectrum of the exciplex is a first energy value, wherein the energy value of a peak wavelength in the absorption band on the side of the lowest energy of the phosphor is a second energy value, wherein a difference between the first energy value and the second energy value is less than 0.2 eV, wherein a triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the fluorescence, wherein the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the first organic compound, and wherein the triplet excitation level (T1) of the host material is lower than a triplet excitation level (T1) of the second organic compound. Light-emitting device according to any one of claims 1 to 3 and 5, further comprising a first light-emitting element, a second light-emitting element, a third light-emitting element and a fourth light-emitting element, wherein the first light-emitting element, the second light-emitting element, the third light-emitting element and the fourth light-emitting element each comprise the anode, the first light-emitting layer, the second light-emitting layer and the cathode, wherein the first light-emitting element overlaps with a red color filter, wherein the second light-emitting element overlaps with a green color filter, wherein the third light-emitting element overlaps with a blue color filter, and wherein the fourth light-emitting element does not overlap with the red color filter, does not overlap with the green color filter and does not overlap with the blue color filter.

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