light-emitting device

Abstract

Light-emitting device, comprising: a light-emitting layer (106), wherein the light-emitting layer (106) comprises a first layer (106(b1)), a second layer (106(b2)) above the first layer (106(b1)) and a third layer (106(b3)) above the second layer (106(b2)), wherein the second layer (106(b2)) is in contact with the first layer (106(b1)) and the third layer (106(b3)), wherein the first layer (106(b1)), the second layer (106(b2)) and the third layer (106(b3)) each contain a phosphorescent substance, wherein an emission peak wavelength of the second layer (106(b2)) is longer than an emission peak wavelength of the first layer (106(b1)) and / or an emission peak wavelength of the third layer (106(b3)), and wherein the first layer (106(b1)), the second layer (106(b2)) and the third layer (106(b3)) each contain substances that form an exciplex.

Description

Technical field

[0001] One embodiment of the present invention relates to a light-emitting device. State of the art

[0002] It is expected that a light-emitting element, using an organic compound as the luminescent material and exhibiting features such as thinness, lightness, fast response times, and low-voltage DC operation, will be used in a next-generation flat panel display. In particular, a display device in which light-emitting elements are arranged in a matrix is ​​expected to offer advantages over a conventional liquid crystal display device, namely a wide viewing angle and excellent visibility.

[0003] The mechanism of light emission can be described as follows: When a voltage is applied between a pair of electrodes, with an EL layer and a phosphor in between, charge carriers (electrons and holes) are injected from the electrodes, and the charge carriers recombine to form excitons; then, energy is released and light is emitted when the excitons return to the ground state. An excited singlet state (S*) and an excited triplet state (T*) are known as excited states. Light emission from the excited singlet state is called fluorescence, and light emission from the excited triplet state is called phosphorescence. The statistical generation ratio of the excited states in a light-emitting element is thought to be S*:T* = 1:3.

[0004] To improve the elemental properties of such a light-emitting element, an active development of a light-emitting element containing a phosphorescent substance has been carried out, in which intersystem crossing (i.e., transition from an excited singlet state to an excited triplet state) occurs readily. Furthermore, a light-emitting element is disclosed in which layers containing different phosphorescent substances are arranged one above the other for white light emission (see, for example, patent document 1). Further exemplary light-emitting elements are disclosed in patent documents 2 to 8. [References] Patent document 1: JP 2004 - 522 276 Patent Document 2: CN 1 02 709 482 A Patent document 3: WO 2013 / 150 968 A1 Patent document 4: US 2013 / 0 292 656 A1 Patent document 5: US 2012 / 0 217 487 A1 Patent document 6: WO 2006 / 008 977 A1 Patent document 7: US 2006 / 0 273 714 A1 Patent document 8: US 2009 / 0 308 456 A1 Disclosure of the invention

[0005] In a light-emitting element with the structure described above, light-emitting layers that emit phosphorescence (i.e., phosphorescent layers) are stacked on top of each other. This structure is used for the following reasons: High emission efficiency can be achieved by utilizing phosphorescence. Furthermore, when a fluorescent layer and a phosphorescent layer are stacked on top of each other, triplet excitons generated in the phosphorescent layer diffuse, and the triplet excitation energy is transferred to the fluorescent layer, leading to deactivation and thus a significant reduction in emission efficiency.

[0006] In light of the foregoing description, one object of an embodiment of the present invention is to provide a light-emitting device that has advantageous emission efficiency despite having a structure in which a fluorescent layer and a phosphorescent layer are arranged one above the other. A further object of an embodiment of the present invention is to provide a light-emitting device that can have low power consumption.

[0007] One embodiment of the present invention is a light-emitting device comprising a light-emitting layer, wherein the light-emitting layer comprises a first layer, a second layer above the first layer, and a third layer above the second layer, wherein the second layer is in contact with the first layer and the third layer, wherein the first layer, the second layer, and the third layer each contain a phosphorescent substance, wherein an emission peak wavelength of the second layer is longer than an emission peak wavelength of the first layer and / or an emission peak wavelength of the third layer, and wherein the first layer, the second layer, and the third layer each contain substances forming an exciplex.

[0008] Another embodiment of the present invention is a light-emitting device comprising: a light-emitting layer, wherein the light-emitting layer comprises a first layer, a second layer above the first layer and a third layer above the second layer, wherein the second layer is in contact with the first layer and the third layer, wherein at least one of the first layer, the second layer and the third layer contains a phosphorescent substance, wherein an emission peak wavelength of the second layer is longer than an emission peak wavelength of the first layer and / or an emission peak wavelength of the third layer, and wherein at least one of the first layer, the second layer and the third layer contains substances forming an exciplex.

[0009] Another embodiment of the present invention is a light-emitting device comprising: a layer arrangement of a first light-emitting layer and a second light-emitting layer, wherein the layer arrangement is located between a pair of electrodes, wherein the first light-emitting layer contains a fluorescent substance, wherein the second light-emitting layer comprises a first layer, a second layer above the first layer, a third layer above the second layer, and a fourth layer above the third layer, wherein the third layer is in contact with the second layer and the fourth layer, wherein the second layer, the third layer, and the fourth layer each contain a phosphorescent substance, and wherein an emission peak wavelength of the third layer is longer than an emission peak wavelength of the second layer and / or an emission peak wavelength of the fourth layer.

[0010] Another embodiment of the present invention is a light-emitting device comprising a layer arrangement of a first light-emitting layer, a second light-emitting layer, a third light-emitting layer, and a fourth light-emitting layer, wherein the layer arrangement is located between a pair of electrodes, wherein the first light-emitting layer contains a fluorescent substance, wherein the second light-emitting layer overlaps the first light-emitting layer, wherein the third light-emitting layer overlaps the second light-emitting layer, wherein the fourth light-emitting layer overlaps the third light-emitting layer, wherein the third light-emitting layer is in contact with the second light-emitting layer and the fourth light-emitting layer, wherein at least one of the second light-emitting layer,the third light-emitting layer and the fourth light-emitting layer contain a phosphorescent substance, and wherein an emission peak wavelength of the third light-emitting layer differs from an emission peak wavelength of the second light-emitting layer and from an emission peak wavelength of the fourth light-emitting layer.

[0011] Another embodiment of the present invention is a light-emitting device comprising: a layer arrangement of a first light-emitting layer and a second light-emitting layer, wherein the layer arrangement is located between a pair of electrodes, wherein the first light-emitting layer contains a fluorescent substance, wherein the second light-emitting layer comprises a first layer, a second layer above the first layer, a third layer above the second layer, and a fourth layer above the third layer, wherein the third layer is in contact with the second layer and the fourth layer, wherein the second layer, the third layer, and the fourth layer each contain a phosphorescent substance, and wherein the second layer and the fourth layer contain the same substances forming an exciplex.

[0012] Another embodiment of the present invention is a light-emitting device comprising: a first light-emitting layer and a second light-emitting layer, wherein the first light-emitting layer is configured to emit fluorescent light, wherein the second light-emitting layer is configured to emit phosphorescent light, wherein the second light-emitting layer comprises a first layer, a second layer above the first layer, and a third layer above the second layer, wherein the phosphorescent light is a mixture of a first phosphorescent light emitted via energy supplied by a first exciplex in the first layer, a second phosphorescent light emitted via energy supplied by a second exciplex in the second layer, and a third phosphorescent light.which is emitted via energy supplied by a third exciplex in the third layer, wherein the first phosphorescent light and the second phosphorescent light differ from each other, and wherein an intensity of the second phosphorescent light is higher than an intensity of the first phosphorescent light and an intensity of the third phosphorescent light.

[0013] Furthermore, an electronic device and a lighting device are also described, each of which includes the light-emitting device. The light-emitting device in this description refers to an image display device and a light source (e.g., a lighting device). The category of light-emitting device may also include any of the following modules: a module in which a connector, such as a flexible printed circuit (FPC) or a tape carrier package (TCP), is attached to a light-emitting device; a module comprising a TCP whose end is provided with a printed circuit board; and a module comprising an integrated circuit (IC) that is directly mounted to a light-emitting element by a chip-on-glass (COG) process.

[0014] One embodiment of the present invention can provide a light-emitting device which, by using the light-emitting element, can exhibit low power consumption. Another embodiment of the present invention can provide an electronic device and a lighting device which can exhibit low power consumption. A further embodiment of the present invention can provide a novel light-emitting device, a novel lighting device, and the like. It should be noted that the description of these effects does not preclude the existence of other effects. An embodiment of the present invention need not necessarily fulfill all of the above-mentioned objectives. Further effects will become apparent from the explanation of the description, the drawings, the claims, and the like, and can be derived from them. Brief description of the drawings Fig. Figure 1 represents a structure of a light-emitting element of an embodiment of the present invention. Fig. 2A and Fig. 2B represents a light-emitting device. Fig. 3A to Fig. 3D, Fig. 3D' Fig. 1 and Fig. 3D' Fig. 2 represent electronic devices. Fig. 4 represents lighting devices. Fig. 5A and Fig. Figure 5B represents structures of a light-emitting element 1 and a light-emitting comparison element 2. Fig. Figure 6 shows emission spectra of the light-emitting element 1 and the light-emitting reference element 2. Fig. Figure 7 shows the reliability of the light-emitting element 1. Fig. Figure 8 shows a luminance-power efficiency characteristic curve of a light-emitting element 3. Fig. Figure 9 shows an emission spectrum of the light-emitting element 3. Fig. Figure 10 shows a luminance-current efficiency characteristic of a light-emitting element 4. Fig. Figure 11 shows an emission spectrum of the light-emitting element 4. Fig. Figure 12 shows the correlation of energy levels in light-emitting layers. Best way of implementing the invention

[0015] Embodiments of the present invention are described in detail with reference to the drawings. (Version 1)

[0016] In this embodiment, a light-emitting element is described which serves to explain the light-emitting device of the present invention.

[0017] In the light-emitting element, an EL layer containing a light-emitting layer is positioned between a pair of electrodes. The light-emitting layer comprises a light-emitting layer (I) that emits fluorescent light and a light-emitting layer (II) that emits phosphorescent light. It should be noted that even if the light-emitting element does not include a charge-generating layer between light-emitting layer (I) and light-emitting layer (II) (i.e., if the light-emitting element is not a tandem element), both fluorescence and phosphorescence can be efficiently obtained. An elemental structure of the light-emitting element is shown below. Fig. 1 described in detail.

[0018] At a Fig.The light-emitting element shown in Figure 1 is an EL layer 103, which includes a light-emitting layer 106, arranged between a pair of electrodes (a first electrode 101 and a second electrode 102). The EL layer 103 has a structure in which a hole injection layer 104, a hole transport layer 105, a light-emitting layer 106, an electron transport layer 107, an electron injection layer 108, and the like are arranged one above the other in that order above the first electrode (anode) 101. The light-emitting layer 106 has a structure in which a light-emitting layer (I) 106a and a light-emitting layer (II) 106b are arranged one above the other. It should be noted that the order in which the light-emitting layer (I) 106a and the light-emitting layer (II) 106b are arranged one above the other is not particularly restricted and can be changed as required.

[0019] The light-emitting layer (I) 106a contains a fluorescent substance and host materials (organic compounds). Triplet excitons from the host materials are efficiently converted into singlet excitons by triplet-triplet annihilation (TTA), and fluorescent light is emitted by the fluorescent substance through energy transfer from singlet excitons.

[0020] In particular, in the light-emitting layer (I) 106a, the lowest triplet excitation energy level (T1 level) of the host material is preferably lower than that of the fluorescent substance. In the light-emitting layer, the proportion of host material is generally much higher than that of fluorescent substances. If the host material is used in combination with the fluorescent substance such that the T1 level of the host material is lower than that of the fluorescent substance, the probability of collision between triplet excitons can be reduced if the triplet excitons generated in the light-emitting layer (I) 106a are captured and localized by only a few fluorescent substances (molecules) in the light-emitting layer (I) 106a; consequently, the probability of triplet excitation is increased.Therefore, the emission efficiency of the fluorescence of the light-emitting layer (I) 106a can be increased. It should be noted that known substances that emit blue light (with an emission spectrum whose peak wavelength is in the range of 400 nm to 480 nm), green light (with an emission spectrum whose peak wavelength is in the range of 500 nm to 560 nm), red light (with an emission spectrum whose peak wavelength is in the range of 580 nm to 680 nm), orange light, yellow light and the like can be used as fluorescent substances in the light-emitting layer (I) 106a, as required.

[0021] The light-emitting layer (II) 106b has a structure in which at least three different layers, i.e. a first layer 106(b1), a second layer 106(b2) and a third layer 106(b3), are arranged one above the other, as in Fig.Figure 1 illustrates this. These three layers each contain two types of organic compounds that can form an excited complex (hereinafter referred to as an exciplex) and a phosphorescent substance. The emission wavelength of an exciplex formed in each layer is longer than the emission wavelength (fluorescence wavelength) of each of the organic compounds forming the exciplex; therefore, the fluorescence spectra of the organic compounds can be converted into emission spectra on the longer wavelength side, thus reducing the operating voltage. Furthermore, energy can be transferred from the exciplex to the phosphorescent substance, resulting in high emission efficiency. It should be noted that the light-emitting layer (II) 106b may, in addition to the three layers described above, include a layer containing an organic compound rather than a phosphorescent substance.

[0022] Furthermore, the three layers are designed such that the emission peak wavelength of the phosphorescence from the second layer 106(b2) is longer than that of the phosphorescence from the first layer 106(b1) and that of the phosphorescence from the third layer 106(b3).

[0023] In particular, the second phosphorescent substance used in the second layer 106(b2) is a substance with an emission peak wavelength longer than that of the first phosphorescent substance used in the first layer 106(b1) and that of the third phosphorescent substance used in the third layer 106(b3).It should be noted that known substances known to emit blue light (with an emission spectrum whose peak wavelength is in the range of 400 nm to 480 nm), green light (with an emission spectrum whose peak wavelength is in the range of 500 nm to 560 nm), red light (with an emission spectrum whose peak wavelength is in the range of 580 nm to 680 nm), orange light, yellow light and the like, can be used as required according to the structure described above.

[0024] It should be noted that the use of such a structure for the light-emitting layer (II) 106b can enable the energy of an exciplex formed in the second layer 106(b2) to be efficiently transferred to the phosphorescent substance with the longest emission peak wavelength, and that diffusion of excitons into the other layers can be suppressed, thus increasing the emission efficiency of the phosphorescence in the light-emitting layer (II) 106b. It should also be noted that, although the light-emitting layer (II) 106b may consist of only the three layers described above, it may include an additional layer containing not a phosphorescent substance, but two types of organic compounds capable of forming an exciplex.

[0025] Organic compounds used as host material or the like in the light-emitting layer (I) 106a and the light-emitting layer (II) 106b, and which are distinct from the phosphorescent substance and the phosphorescent substance, can mainly be electron transport materials with an electron mobility of 10 -6 cm 2 / Vs or higher and hole transport materials with a hole mobility of 10 -6 cm 2 / Vs or higher. It should be noted that for each of the layers containing the phosphorescent substances in the light-emitting layer (II) 106b, two or more types of the organic compounds described above are selected such that an exciplex can be formed.

[0026] By dispersing the light-emitting substance (the fluorescent or phosphorescent substance) in the organic compounds within the light-emitting layer (I) 106a or the light-emitting layer (II) 106b, crystallization within the light-emitting layer can be suppressed. Furthermore, it is possible to suppress concentration quenching due to a high concentration of the light-emitting substance; therefore, the emission efficiency of the light-emitting element can be increased.

[0027] The T1 level of the organic compound is preferably higher than that of the phosphorescent substance in the light-emitting layer (II) 106b for the following reason. If the T1 level of an electron transport material or a hole transport material is lower than that of the phosphorescent substance, the triplet excitation energy of the phosphorescent substance, which contributes to light emission, is quenched by the electron transport material or the hole transport material, leading to a reduction in emission efficiency.

[0028] By producing a light-emitting element that meets the conditions described above, a light-emitting element can be obtained that can emit fluorescent light and phosphorescent light. Examples of the color combinations of fluorescent light emitted by light-emitting layer (I) 106a and phosphorescent light emitted by light-emitting layer (II) 106b, represented by "the color of the fluorescent light emitted by light-emitting layer (I) 106a\the color of the phosphorescent light emitted by light-emitting layer (II) 106b", include "blue\green.red.green", "blue\blue.red.green", "blue\yellow-red-green", "blue\green-red-yellow", "blue\yellow-red-yellow", "green\green-red-green", "green\blue.red.green", "green\yellow-red-green", "green\green.red.yellow", "green\yellow-red-yellow", "red\green.red.green", "Red\Blue. Red.Green", "Red\Yellow-Red-Green", "Red\Green.Red.Yellow” and “Red\Yellow.Red.Yellow”. It should be noted that the combinations described above are also possible if the light-emitting layer (I) 106a and the light-emitting layer (II) 106b are arranged on top of each other in reverse order.

[0029] When a fluorescent layer and a phosphorescent layer are arranged one above the other, the triplet excitation energy generated in the phosphorescent layer is generally transferred to a host material in the fluorescent layer to cause non-radiative deactivation, resulting in a reduction of emission efficiency. However, in the light-emitting device of one embodiment of the present invention, the triplet excitation energy of an exciplex formed in the phosphorescent layer is transferred to the phosphorescent substance, thus obtaining light emission. Furthermore, it is unlikely that an exciton will diffuse from the exciplex into a substance other than the phosphorescent substance. Therefore, both phosphorescence and fluorescence can be obtained efficiently.It should be noted that in one embodiment of the present invention, an excited singlet state can be easily formed by TTA in the light-emitting layer (I) 106a, which allows the triplet excitation energy to be converted into fluorescence by an exciplex formed in the light-emitting layer (II) 106b, even when the transfer of triplet excitation energy occurs.

[0030] Fig. Figure 12 shows the correlation between the energy levels of substances and an exciplex in the light-emitting element. Fig. 12 represents S FH a singlet excitation level of a host material in the light-emitting layer (I) 106a; T FH , a triplet excitation level of the host material in the light-emitting layer (I) 106a; S FG , a singlet excitation level of a guest material (a fluorescent substance) in the light-emitting layer (I) 106a; T FG, a triplet excitation level of the guest material (the fluorescent substance in the light-emitting layer (I) 106a; S PH , a singlet excitation level of a host material (a first organic compound or a second organic compound) in the light-emitting layer (II) 106b; T PH , a triplet excitation level of the host material (the first organic compound or the second organic compound) in the light-emitting layer (II) 106b; S E , a singlet excitation level of an exciplex in the light-emitting layer (II) 106b; T E , a triplet excitation level of the exciplex in the light-emitting layer (II) 106b; and T PG , a triplet excitation level of a guest material (a phosphorescent substance) in the light-emitting layer (II) 106b.

[0031] As in Fig.As shown in Figure 12, TTA occurs because excited triplet molecules of the host material collide with each other in the light-emitting layer (I) 106a, and some of the excited triplet molecules of the host material are converted into excited singlet molecules, while thermal deactivation of some of the excited triplet molecules occurs. Then the energy of the excited singlet state generated by TTA (S FG ) of the host material is transferred to the excited singlet state of the fluorescent substance, and the singlet excitation energy is converted into fluorescence.

[0032] In the light-emitting layer (II) 106b, the excitation levels (S E and T E ) of the exciplex lower than the excitation levels (S PH and T PH) of the host materials (the first organic compound and the second organic compound); therefore, no excitation energy transfer from the exciplex to the host material occurs. Furthermore, no energy transfer occurs from one exciplex to another. If the excitation energy of the exciplex is transferred to the guest material (the phosphorescent substance), the excitation energy can be converted into light emission. As described above, the triplet excitation energy hardly diffuses and can be converted into light emission in the light-emitting layer (II) 106b.

[0033] Therefore, light emission can be obtained with favorable efficiency from both the light-emitting layer (I) 106a and the light-emitting layer (II) 106b, even if a small energy transfer (e.g., an energy transfer of T) is required. PHthe phosphorescent substance at the interface between the light-emitting layer (I) 106a and the light-emitting layer (II) 106b on T FH or T FC ) occurs at the interface. In the light-emitting layer (I) 106a, the excited singlet state is generated by TTA from the triplet excitation energy. Therefore, even if energy transfer occurs at the interface, some of the transferred energy is converted into fluorescence. This can suppress the energy loss.

[0034] Next, a specific example will be described in which the aforementioned light-emitting element is manufactured.

[0035] The first electrode (anode) 101 and the second electrode (cathode) 102 can be a metal, an alloy, an electrically conductive compound, a mixture thereof, and the like. In particular, indium oxide-tin oxide (indium tin oxide), indium oxide-tin oxide containing silicon or silicon oxide, indium oxide-zinc oxide (indium zinc oxide), indium oxide containing tungsten oxide and zinc oxide, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), and titanium (Ti) can be used. Furthermore, an element belonging to Group 1 or Group 2 of the periodic table, that is, an alkali metal such as lithium (Li) or cesium (Cs), an alkaline earth metal such as... B. Calcium (Ca) or Strontium (Sr), Magnesium (Mg), an alloy containing such an element (e.g. MgAg or AlLi), a rare earth metal, such asEuropium (Eu) or ytterbium (Yb), an alloy containing such an element, graphene, and the like may be used. The first electrode (anode) 101 and the second electrode (cathode) 102 may, for example, be formed by a sputtering process or an evaporation process (including a vacuum evaporation process).

[0036] The hole injection layer 104 injects holes into the light-emitting layer 106 via the hole transport layer 105, which has high hole transport properties. The hole injection layer 104 contains a hole transport material and an acceptor substance, such that the acceptor substance extracts electrons from the hole transport material to create holes, and the holes are injected into the light-emitting layer 106 via the hole transport layer 105. The hole transport layer 105 is formed using a hole transport material.

[0037] Specific examples of the hole transport material used for the hole injection layer 104 and the hole transport layer 105 include aromatic amine compounds, such as... B. 4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-Bis(3-methylphenyl)-N,N'-diphenyl-[1,1'biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4"-Tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), 4,4',4"-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4"-Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA) and 4,4'-Bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB); 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 include carbazole derivatives, such as...4,4'-Di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-Tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), and 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA). The substances listed here are mainly those exhibiting a hole mobility of 10. -6 cm 2 exhibiting / Vs or higher. It should be noted that any substance other than those listed here can be used, as long as its hole transport property is higher than its electron transport property.

[0038] 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: PTPD-MA) and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: poly-TPD).

[0039] Examples of the acceptor substance used for the hole injection layer 104 include oxides of metals belonging to groups 4 to 8 of the periodic table. Molybdenum oxide is particularly preferred.

[0040] The light-emitting layer 106 is a layer arrangement consisting of the light-emitting layer (I) 106a and the light-emitting layer (II) 106b, each of which has the structure described above.

[0041] Examples of the fluorescent substance used in the light-emitting layer (I) 106a are substances which convert singlet excitation energy into light emission.

[0042] Examples of the fluorescent substance include N,N'-Bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP). 4-(10-Phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N"-(2-tert-Butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-Diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-Diphenyl-2-anthryl)phenyl]-N,N',N'triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N",N",N"',N"'-Octaphenyldibenzo[g,p]chrysen-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-Diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-Bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-Triphenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-Diphenylquinacridone (abbreviation: DPQd), Rubrene, 5,12-Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(Dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanenitrile (abbreviation: DCM1), 2-{2-Methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanenitrile (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-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1 H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), {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}propanedinitrile (abbreviation: BisDCJTM). Condensed aromatic diamine compounds, typically pyrenediamine compounds such as 1,6-FLPAPrn and 1,6-MemFLPAPrn, are particularly preferred due to their high hole-trapping properties, high emission efficiency, and high reliability.

[0043] Examples of the phosphorescent substance used for the light-emitting layer (II) 106b are substances which convert triplet excitation energy into light emission.

[0044] The examples include Bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2'}iridium(III)picolinate (abbreviation: Ir(CF3ppy)2(pic)), Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]iridium(III)acetylacetonate (abbreviation: Flracac), Tris(2-phenylpyridinato)iridium(III) (abbreviation: Ir(ppy)3), Bis(2-phenylpyridinato)iridium(III)acetylacetonate (abbreviation: Ir(ppy)2(acac)), Tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: Tb(acac)3(Phen)), Bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: Ir(bzq)2(acac)), Bis(2,4-diphenyl-1,3-oxazolato-N,C 2' )iridium(III)acetylacetonate (abbreviation: Ir(dpo)2(acac)), Bis{2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2'}iridium(III)acetylacetonate (abbreviation: Ir(p-PFph)2(acac)),Bis(2-phenylbenzothiazolato-N,C 2' )iridium(III)acetylacetonate (abbreviation: Ir(bt)2(acac)), Bis[2-(2'-benzo[4,5-a]thienyl)pyridinato-N,C 3' ]Iridium(III)acetylacetonate (abbreviation: Ir(btp)2(acac)),Bis(1-phenylisoquinolinato-N,C 2')iridium(III)acetylacetonate (abbreviation: Ir(piq)2(acac)), (Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac)), (Acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]), (Acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), (Acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: Ir(tppr)2(acac)), Bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), (Acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (Acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), 2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphyrin-platinum(II) (abbreviation: PtOEP), 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)).,

[0045] It should be noted that a thermally activated delayed fluorescence (TADF) material can also be used instead of the phosphorescent substances. It should be noted that the "delayed fluorescence" exhibited by the TADF material refers to light emission that has the same emission spectrum as normal fluorescence and a very long lifetime. The lifetime is 10 -6 Seconds or longer, preferably 10 -3 Seconds or longer.

[0046] Specific examples of TADF material include fullerene, a derivative thereof, an acridine derivative such as proflavin, and eosin. Further examples include a metal-containing porphyrin, such as porphyrin containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of metal-containing porphyrin include a protoporphyrin tin fluoride complex (SnF2(Proto IX)), a mesoporphyrin tin fluoride complex (SnF2(Meso IX)), a hematoporphyrin tin fluoride complex (SnF2(Hämato IX)), a coproporphyrin tetramethyl ester tin fluoride complex (SnF2(Copro III-4Me)), an octaethylporphyrin tin fluoride complex (SnF2(OEP)), an etioporphyrin tin fluoride complex (SnF2(Etio I)) and an octaethylporphyrin platinum chloride complex (PtCl2(OEP)).Alternatively, a heterocyclic compound with 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 (PIC-TRZ). It should be noted that a material in which the π-electron-rich heteroaromatic ring is directly bonded to the π-electron-poor heteroaromatic ring is particularly preferred, as this increases both the donor property of the π-electron-rich heteroaromatic ring and the acceptor property of the π-electron-poor heteroaromatic ring, and reduces the energy difference between the S1 level and the T1 level.

[0047] Examples of the organic compound used for the light-emitting layer (I) 106a include anthracene compounds, such as... B. 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). It should be noted that the use of a substance with an anthracene backbone as a host material allows for the creation of a light-emitting layer with high emissivity and durability. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred due to their favorable properties.

[0048] The electron transport material, which is an organic compound used for the light-emitting layer (II) 106b, is preferably a π-electron-deficient heteroaromatic compound, such as a nitrogen-containing heteroaromatic compound, examples of which include: quinoxaline derivatives and dibenzoquinoxaline derivatives, such as B. 2-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[4-(3,6-Diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II) and 6-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II).

[0049] A π-electron-rich heteroaromatic compound (e.g., a carbazole derivative or an indole derivative) or an aromatic amine compound is preferred as the hole transport material, which is an organic compound used for the light-emitting layer (II) 106b, examples of which include: 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1 BP), 4,4'-di(1-naphthyl)-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), 4,4',4"-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), 2,7-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9'-bifluorene (abbreviation: DPA2SF), N,N'-Bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N-(9,9-Dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), N,N',N"-Triphenyl-N,N',N"-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B),2-[N-(9-Phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2-[N-(4-Diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), N,N'-Bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), 4,4'-Bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (abbreviation: TPD), 4,4'-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N-(9,9-Dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3-[N-(4-Diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 4,4'-Bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (Abbreviation: DNTPD), 3,6-Bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2) and 3,6-Bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2).,

[0050] The electron transport layer 107 is a layer containing a substance with high electron transport properties. A metal complex can be used for the electron transport layer 107, such as Alq3, Tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq3), Bis(10-hydroxybenzo[h]-quinolinato)beryllium (abbreviation: BeBq2), BAlq, Zn(BOX)2, or Bis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ)2). A heteroaromatic compound, such as... B. 2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-Bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP) or 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), be used.A high-molecular-weight compound, such as poly(2,5-pyridindiyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), or poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy), can also be used. The substances listed here are mainly those with an electron mobility of 10. -6 cm 2 exhibiting / Vs or higher. It should be noted that any substance other than those listed here can be used for electron transport layer 107, as long as its electron transport property is higher than its hole transport property.

[0051] The electron transport layer 107 is not limited to a single layer but can be a layer arrangement of two or more layers, each containing any one of the substances listed above.

[0052] The electron injection layer 108 is a layer containing a substance with high electron injection properties. Suitable materials for the electron injection layer 108 include an alkali metal, an alkaline earth metal, or a compound thereof, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF₂), or lithium oxide (LiO₂). x ). A rare-earth metal compound, such as erbium fluoride (ErF3), can also be used. An electride can also be used for the electron injection layer 108. Examples of electrides include substances in which electrons are added to calcium oxide-aluminum oxide in a high concentration. Any of the substances mentioned above can be used to form the electron transport layer 107.

[0053] A composite material in which an organic compound and an electron donor are mixed can also be used for the electron injection layer 108. The composite material exhibits excellent electron injection and electron transport properties because the electron donor generates electrons in the organic compound. In this case, the organic compound is preferably a material that can transport the generated electrons very well. In particular, the substances mentioned above (e.g., a metal complex or a heteroaromatic compound) can be used to form the electron transport layer 107. A substance that has the property of donating electrons to the organic compound can be used as the electron donor.In particular, an alkali metal, an alkaline earth metal, and a rare earth metal are preferred, wherein lithium, cesium, magnesium, calcium, erbium, and ytterbium are specified. Furthermore, an alkali metal oxide or an alkaline earth metal oxide is preferred, wherein lithium oxide, calcium oxide, and barium oxide are specified. A Lewis base, such as magnesium oxide, may also be used. An organic compound, such as tetrathiafulvalene (abbreviation: TTF), may also be used.

[0054] It should be noted that the hole injection layer 104, the hole transport layer 105, the light-emitting layer 106 (the light-emitting layer (I) 106a and the light-emitting layer (II) 106b), the electron transport layer 107 and the electron injection layer 108 can each be formed by a process such as an evaporation process (e.g. a vacuum evaporation process), an inkjet process or a coating process.

[0055] In the light-emitting element described above, charge carriers are injected due to a potential difference generated between the first electrode 101 and the second electrode 102. The holes and electrons recombine in the EL layer 103, thereby emitting light. The emitted light is then 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 electrodes that exhibit light-transmitting properties.

[0056] A light-emitting element having the structure described in this embodiment can emit fluorescent light and phosphorescent light, in particular phosphorescent light with high efficiency, which increases the emission efficiency of the entire light-emitting element.

[0057] It should be noted that the structure described in this embodiment can be combined with any of the structures described in the other embodiments, as required. (Version 2)

[0058] In this embodiment, a light-emitting active matrix device is used as an example of a light-emitting device of the present invention, based on… Fig. 2A and Fig. 2B described. It should be noted that the light-emitting element described in embodiment 1 can be used for the light-emitting device described in this embodiment.

[0059] Fig. 2A is a top view showing the light-emitting device, and Fig. 2B is a cross-sectional view along the dashed line AA' in Fig.2A. The light-emitting active matrix device of this embodiment comprises, above an element substrate 201, a pixel section 202, a driver circuit section (a source line driver circuit) 203, and driver circuit sections (gate line driver circuits) 204a and 204b. The pixel section 202, the driver circuit section 203, and the driver circuit sections 204a and 204b are sealed with a sealing material 205 between the element substrate 201 and a sealing substrate 206.

[0060] Furthermore, a connecting line 207 is provided above the element substrate 201 for connecting an external input terminal, from which a signal (e.g., a video signal, a clock signal, a start signal, or a reset signal) or an electrical potential is transmitted to the driver circuit section 203 and the driver circuit sections 204a and 204b. An example is shown here in which a flexible printed circuit (FPC) 208 is provided as the external input terminal. Although only the FPC is shown here, the FPC can be equipped with a printed circuit board (PWB). The category of light-emitting device in this description includes not only the light-emitting device as such, but also the light-emitting device equipped with the FPC or the PWB.

[0061] Next, a cross-sectional structure will be created based on... Fig.2B described. The driver circuit section and the pixel section are formed above the element substrate 201; here, the driver circuit section 203, which is the source line driver circuit, and the pixel section 202 are shown.

[0062] Driver circuit section 203 is an example combining a FET 209 and a FET 210. It should be noted that the FET 209 and the FET 210 contained in driver circuit section 203 can each be implemented with a circuit containing transistors of the same line type (either an n-channel transistor or a p-channel transistor), or with a CMOS circuit containing an n-channel transistor and a p-channel transistor. In this embodiment, a driver-integrated circuit is described in which the driver circuit is implemented on the substrate; however, the driver circuit is not necessarily implemented on the substrate and can be implemented off-substrate.

[0063] The pixel section 202 comprises a plurality of pixels, each containing a switching FET 211, a current-controlling FET 212, and a first electrode (anode) 213 electrically connected to a line (a source electrode or a drain electrode) of the current-controlling FET 212. Although in this embodiment the pixel section 202 comprises two FETs, namely the switching FET 211 and the current-controlling FET 212, an embodiment of the present invention is not limited thereto. The pixel section 202 can, for example, comprise three or more FETs in combination with a capacitor.

[0064] For example, a staggered transistor or an inverted staggered transistor can be used as FETs 209, 210, 211, and 212. Examples of semiconductor materials that can be used for FETs 209, 210, 211, and 212 include Group IV semiconductors (e.g., silicon), Group III semiconductors (e.g., gallium), compound semiconductors, oxide semiconductors, and organic semiconductors. Furthermore, there is no particular restriction regarding the crystallinity of the semiconductor material, and an amorphous or crystalline semiconductor can be used. In particular, an oxide semiconductor is preferably used for FETs 209, 210, 211, and 212. Examples of the oxide semiconductor include an In-Ga oxide and an In-M-Zn oxide (M being Al, Ga, Y, Zr, La, Ce, or Nd).For example, an oxide semiconductor material having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more, is used for the FETs 209, 210, 211 and 212, so that the reverse current (off-state current) of the transistors can be reduced.

[0065] An insulator 214 is designed to cover edge sections of the first electrode 213. In this embodiment, the insulator 214 is formed using a positive photosensitive acrylic resin. The first electrode 213 is used as the anode in this embodiment.

[0066] The insulator 214 preferably has a curved surface with a curvature at its upper end section or its lower end section. This makes it advantageous to cover the insulator 214 with a film. For example, the insulator 214 can be formed using either a negatively photosensitive resin or a positively photosensitive resin. The material for the insulator 214 is not limited to an organic compound, and an inorganic compound, such as silicon dioxide, silicon oxynitride, or silicon nitride, can also be used.

[0067] An EL layer 215 and a second electrode (cathode) 216 are arranged one above the other above the first electrode (anode) 213. At least one light-emitting layer is provided in the EL layer 215, wherein the light-emitting layer has the multilayer structure described in embodiment 1. In addition to the light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a charge generation layer, and the like can be provided in the EL layer 215, as required.

[0068] A light-emitting element 217 is formed from a layered arrangement of the first electrode (anode) 213, the EL layer 215, and the second electrode (cathode) 216. Any of the materials specified in embodiment 1 can be used for the first electrode (anode) 213, the EL layer 215, and the second electrode (cathode) 216. Although not shown, the second electrode (cathode) 216 is electrically connected to the FPC 208, which is an external input terminal.

[0069] Although the cross-sectional view in Fig.While 2B represents only a single light-emitting element 217, a multitude of light-emitting elements are arranged in a matrix within pixel section 202. Light-emitting elements emitting light in three types of colors (R, G, and B) are selectively formed within pixel section 202, thereby creating a light-emitting device suitable for full-color display. In addition to the light-emitting elements emitting light in three types of colors (R, G, and B), light-emitting elements emitting light in white (W), yellow (Y), magenta (M), cyan (C), and the like can be formed. For example, the light-emitting elements emitting light in multiple types of colors are used in combination with the light-emitting elements emitting light in three types of colors (R, G, and B), creating effects such as...An improvement in color purity and a reduction in power consumption can be achieved. An optical microresonator (microcavity) structure, which utilizes a light resonance effect between electrodes, can be employed to reduce the linewidth of each emission color. A light-emitting device suitable for full-color display can also be produced by combining it with color filters. Furthermore, a light-emitting element can be used in which a tandem structure is combined with the structure of the light-emitting element as described above.

[0070] The sealing substrate 206 is further attached to the element substrate 201 by means of the sealing agent 205, such that a light-emitting element 217 is provided in a space 218 which is enclosed by the element substrate 201, the sealing substrate 206 and the sealing agent 205. The space 218 can be filled with an inert gas (such as nitrogen or argon) or with the sealing agent 205.

[0071] The sealant 205 preferably consists of an epoxy-based resin or a glass frit. The material preferably allows as little moisture and oxygen to pass through as possible. The sealing substrate 206 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. In the case where a glass frit is used as the sealant, both the element substrate 201 and the sealing substrate 206 are preferably glass substrates to achieve high adhesion.

[0072] As described above, the light-emitting active matrix device can be manufactured. It should be noted that the light-emitting active matrix device is described as an example of a light-emitting device of this embodiment; a light-emitting passive matrix device can be manufactured using the light-emitting element described in embodiment 1, as described above.

[0073] It should be noted that in the fabrication of the light-emitting active matrix device, there are no particular restrictions regarding the structure of the transistor (FET). For example, a staggered FET or an inverted staggered FET can be used, depending on the requirements. A driver circuit formed on a FET substrate can be implemented with either an n-type or a p-type FET, or it can be implemented with either only an n-type or only a p-type FET. Furthermore, there are no particular restrictions regarding the crystallinity of a semiconductor film used for the FET. For example, either an amorphous semiconductor film or a crystalline semiconductor film can be used. Examples of semiconductor materials include Group IV semiconductors (e.g., silicon), Group III semiconductors (e.g.,Gallium), compound semiconductors (including oxide semiconductors) and organic semiconductors.

[0074] It should be noted that the structure described in this embodiment can be combined with either of the other two embodiments as required. (Version 3)

[0075] In this embodiment, examples of various electronic devices manufactured using a light-emitting device of an embodiment of the present invention are shown by reference to Fig. 3A to Fig. 3D, Fig. 3D' Fig. 1 and Fig. 3D' Fig. 2 described.

[0076] Examples of electronic devices that incorporate the light-emitting device 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 game consoles, portable information terminals, audio playback devices, and large gaming machines such as pinball machines. Specific examples of the electronic devices are in Fig. 3A to Fig. 3D, Fig. 3D' Fig. 1 and Fig. 3D' Fig. 2 shown.

[0077] Fig.Figure 3A represents an example of a television set. In the television set 7100, a display section 7103 is installed in a housing 7101. Images can be displayed by the display section 7103, and the light-emitting device can be used for the display section 7103. Additionally, the housing 7101 is supported by a base 7105.

[0078] The 7100 television can be operated using a control switch on the housing 7101 or with a separate remote control 7110. The remote control 7110's control buttons 7109 allow the user to select television channels, adjust the volume, and control images displayed on the display section 7103. Furthermore, the remote control 7110 can be equipped with a display section 7107 to show the data output by the remote control 7110.

[0079] It should be noted that the 7100 television set is equipped with a receiver, a modem, and the like. Using the receiver, general television broadcasts can be received. Furthermore, when the television set is connected to a communication network, either wired or wirelessly via the modem, one-way (from a sender to a receiver) or two-way (between a sender and a receiver or between receivers) information communication can take place.

[0080] Fig. Figure 3B represents a computer comprising a main unit 7201, a case 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 can be manufactured using the light-emitting device for the display section 7203.

[0081] Fig.3C represents a smartwatch comprising a case 7302, a display panel 7304, control buttons 7311 and 7312, a connection port 7313, a band 7321, a clasp 7322 and the like.

[0082] The display field 7304, which is mounted in the housing 7302 serving as a frame, has a non-rectangular display area. The display field 7304 can display an icon 7305, which shows the time, another icon 7306, and the like.

[0083] The in Fig.The smartwatch shown in Figure 3C can have various functions, such as a function to display different information (e.g., a still image, a moving image, and a text image) on a display section, a touchscreen function, a function to display a calendar, date, time, and the like, a function to control processing using various software (programs), a wireless communication function, a function to connect to different computer networks using a wireless communication function, a function to send and receive various data using a wireless communication function, and a function to read a program or data stored in a recording medium and to display the program or data on a display section.

[0084] The 7302 housing can contain a speaker, a sensor (a sensor with a function for measuring force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electrical power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays), a microphone, and the like. It should be noted that the smartwatch can be manufactured using the 7304 light-emitting device for the display panel.

[0085] Fig.Figure 3D represents an example of a mobile phone (e.g., a smartphone). A mobile phone 7400 includes a housing 7401, which is equipped with a display section 7402, a microphone 7406, a speaker 7405, a camera 7407, an external connection port 7404, an operating button 7403, and the like. In the case where the light-emitting element is formed over a flexible substrate, the light-emitting element can be used for the display section 7402, which, as in Fig. It is represented in 3D and has a curved surface.

[0086] If the display section 7402 of the in Fig. When the 3D-displayed mobile phone 7400 is touched with a finger or similar object, data can be entered into the mobile phone 7400. Furthermore, actions such as making a call and composing an email can be performed by touching the display section 7402 with a finger or similar object.

[0087] There are essentially three screen modes for the 7402 display section. The first mode is a display mode, primarily used to show an image. The second mode is an input mode, primarily used to enter data, such as text. The third mode is a combined display and input mode.

[0088] For example, when making a call or composing an email, a text input mode primarily used for entering characters is selected for display section 7402, allowing the input of characters displayed on the screen. In this case, it is preferred that a keyboard or numeric keypad be displayed across almost the entire screen of display section 7402.

[0089] If a detector device, such as a gyroscope or accelerometer, is provided in the 7400 mobile phone, the display on the screen of the 7402 display section can be automatically switched by determining the orientation of the 7400 mobile phone (depending on whether the mobile phone is positioned horizontally or vertically).

[0090] The screen modes are switched by touching the display section 7402 or by using the button 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 moving image signal, the screen mode switches to display mode. If the signal is a text data signal, the screen mode switches to input mode.

[0091] Furthermore, in input mode, if no input is made by touching the display section 7402 for a certain period of time while a signal detected by an optical sensor in the display section 7402 is being recorded, the screen mode can be controlled to switch from input mode to display mode.

[0092] The display section 7402 can serve as an image sensor. For example, an image of a handprint, fingerprint, or the like can be captured by touching the display section 7402 with the palm or finger, thus enabling personal authentication. Furthermore, if a backlight or a scanning light source emitting near-infrared light is provided in the display section, an image of a finger vein, palm vein, or the like can be captured.

[0093] Furthermore, the light-emitting device can be used for a mobile phone that has a structure that is in Fig. 3D' Fig. 1 or Fig. 3D' Fig. Figure 2 shows another structure of the mobile phone (e.g., smartphones).

[0094] It should be noted that in the case of the in Fig. 3D' Fig. 1 or Fig. 3D' Fig. The structure shown in Figure 2 allows text data, image data, or the like to be displayed on secondary screens 7502(1) and 7502(2) of housings 7500(1) and 7500(2), as well as on primary screens 7501(1) and 7501(2). Such a structure enables a user to easily view text data, image data, or the like displayed on the secondary screens 7502(1) and 7502(2) while the mobile phone is in the user's breast pocket.

[0095] As described above, the electronic devices can be obtained by using the light-emitting device of an embodiment of the present invention. It should be noted that the light-emitting device for electronic devices can be used in various fields, not limited to the electronic devices described in this embodiment.

[0096] It should be noted that the structure described in this embodiment can be combined with either of the other two embodiments as required. (Version 4)

[0097] In this embodiment, examples of lighting devices, each using a light-emitting device of an embodiment of the present invention, are given by reference to Fig. 4 described.

[0098] Fig.Figure 4 presents an example in which the light-emitting device is used as an interior lighting device 8001. Since the light-emitting device can have a large surface area, it can be used for a lighting device that covers a large area. Furthermore, by using a housing with a curved surface, a lighting device 8002 in which a light-emitting area has a curved surface can also be obtained. A light-emitting element contained in the light-emitting device described in this embodiment has the form of a thin film, which allows for greater freedom in the design of the housing. Consequently, the lighting device can be artistically designed in various ways. In addition, a wall of the room can be provided with a large lighting device 8003.

[0099] If the light-emitting device is used for a table by serving as the table's surface, a lighting device 8004 with a function as a table can be obtained. If the light-emitting device is used as part of another piece of furniture, a lighting device serving as that piece of furniture can be obtained.

[0100] As described above, various lighting devices can be obtained that include the light-emitting device. It should be noted that these lighting devices are also embodiments of the present invention.

[0101] It should be noted that the structure described in this embodiment can be combined with either of the other two embodiments as required. [Example 1]

[0102] In this example, a light-emitting element 1 and a light-emitting comparison element 2 were manufactured for comparison, and the properties of the light-emitting elements were compared.

[0103] Although both light-emitting element 1 and light-emitting reference element 2 have a light-emitting layer (I) that emits fluorescent light and a light-emitting layer (II) that emits phosphorescent light, the light-emitting elements have different structures with respect to the light-emitting layers (II). Since the light-emitting elements have the same structure except for the structures of the light-emitting layers (II), the components of light-emitting element 1 are referred to as... Fig. 5A and the components of the light-emitting reference element 2 in Fig.5B is described collectively using the same reference numerals. It should be noted that a light-emitting layer (II) 506b of the light-emitting element 1 has a multilayer structure in which a third layer 506(b3), formed between a second layer 506(b2) and a fourth layer 506(b4), emits light with an emission peak wavelength longer than that of light emitted by the second layer 506(b2) and the fourth layer 506(b4). The structural formulas and abbreviations of the materials used in this example are shown below. <<Herstellung des Licht emittierenden Elementes 1 und des Licht emittierenden Vergleichselementes 2> >

[0104] The first electrode 501 is an electrode that serves as an anode and was formed as follows: Indium tin oxide (ITO) was deposited by sputtering to a thickness of 110 nm over a glass substrate 500 with a refractive index of 1.84. The electrode area was set to 2 mm × 2 mm.

[0105] As a pretreatment, the surface of substrate 500 was washed with water and then subjected to UV-ozone treatment for 370 seconds. Afterwards, substrate 500 was transferred to a vacuum evaporation device where the pressure was set to approximately 10 -4 Pa had been reduced, and it was fired for 60 minutes in a vacuum at 190 °C in a heating chamber of the vacuum evaporation device, and then the substrate 500 was cooled over a period of approximately 30 minutes.

[0106] An EL layer 503 and a second electrode 502 are formed successively over the first electrode 501. It should be noted that, as in Fig. Figure 5A shows that the EL layer 503 in the light-emitting element 1 comprises the following layers: a hole injection layer 504, a hole transport layer 505, a light-emitting layer 506 (a light-emitting layer (I) 506a and a light-emitting layer (II) 506b), an electron transport layer 507, and an electron injection layer 508. The light-emitting layer (II) 506b has a layer arrangement of multiple layers (506(b1), 506(b2), 506(b3), and 506(b4)) containing different substances. As shown in Fig.As shown in Figure 5B, the light-emitting layer 506 in the light-emitting reference element 2 includes a light-emitting layer (II) 506b' with a structure that differs from that of the light-emitting layer (II) 506b in the light-emitting element 1. Therefore, in this embodiment, parts that are the same in the light-emitting element 1 and in the light-emitting reference element 2 are described collectively, and only different parts are described individually.

[0107] After the pressure of the vacuum evaporation device is set to 10 -4After the Pa level had been reduced, 1,3,5-tri(dibenzothiophen-4-yl)benzene (abbreviation: DBT3P-II) and molybdenum(VI) oxide were jointly deposited in a mass ratio of 1:0.5 (= DBT3P-II: molybdenum oxide), thereby forming the hole injection layer 504 over the first electrode 501. It should be noted that co-evaporation is an evaporation process in which a variety of different substances are simultaneously evaporated from their respective evaporation sources. It should also be noted that the thickness of the hole injection layer 504 was set to 30 nm in both the light-emitting element 1 and the light-emitting reference element 2.

[0108] The hole transport layer 505 was formed in a thickness of 10 nm by depositing PCPPn over the hole injection layer 504.

[0109] The light-emitting layer (I) 506a was formed by the co-deposition of 7-[4-(10-Phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and N,N'-Bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyren-1,6-diamine (abbreviation: 1,6mMemFLPAPrn) in a mass ratio of 1:0.025 (= cgDBCzPA: 1,6mMemFLPAPrn) over the hole transport layer 505 such that it has a thickness of 10 nm.

[0110] The light-emitting layer (II) 506b of the light-emitting element 1, which is in Fig. The structure shown in Figure 5A has a layered arrangement consisting of a plurality of layers, in particular the first layer 506(b1), the second layer 506(b2), the third layer 506(b3), and the fourth layer 506(b4). It should be noted that the second layer 506(b2), the third layer 506(b3), and the fourth layer 506(b4) can each emit phosphorescent light due to energy transfer from an exciplex.

[0111] The first layer 506(b1) was formed by jointly depositing 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) and N-(1,1'-Biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) in a mass ratio of 0.2:0.8 (= 2mDBTBPDBq-II: PCBBiF) over the light-emitting layer (I) 506a such that it has a thickness of 2 nm.

[0112] The second layer 506(b2) was formed by jointly depositing 2mDBTBPDBq-II, PCBBiF and (Acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]) in a mass ratio of 0.1:0.9:0.06 (= 2mDBTBPDBq-II: PCBBiF: [Ir(tBuppm)2(acac)]) over the first layer 506(b1) such that it has a thickness of 5 nm.

[0113] The third layer 506(b3) was formed by co-deposition of 2mDBTBPDBq-II, PCBBiF and Bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,4-pentanedionato-κ 2 O,O')iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(acac)]) in a mass ratio of 0.1:0.9:0.03 (= 2mDBTBPDBq-II: PCBBiF: [Ir(dmdppr-dmp)2(acac)]) over the second layer 506(b2) such that it has a thickness of 5 nm.

[0114] The fourth layer 506(b4) was formed by jointly depositing 2mDBTBPDBq-II, PCBBiF and [Ir(tBuppm)2(acac)] in a mass ratio of 0.8:0.2:0.06 (= 2mDBTBPDBq-II: PCBBiF: [Ir(tBuppm)2(acac)]) over the third layer 506(b3) such that it has a thickness of 20 nm.

[0115] The second light-emitting layer (II) 506b' in the light-emitting reference element 2, which is in Fig.Figure 5B shows a layered arrangement consisting of a plurality of layers, in particular the first layer 506(b1), a second layer 506(b2') and a third layer 506(b3'). It should be noted that the first layer 506(b1), being identical to the first layer 506(b1) in the light-emitting element 1, can be formed in the same way and that the description of the first layer 506(b1) is omitted.

[0116] The second layer 506(b2') was formed by jointly depositing 2mDBTBPDBq-II, PCBBiF and [Ir(dmdppr-dmp)2(acac)] in a mass ratio of 0.1:0.9:0.06 (2mDBTBPDBq-II: PCBBiF: [Ir(dmdppr-dmp)2(acac)]) over the first layer 506(b1) such that it has a thickness of 5 nm.

[0117] The third layer 506(b3') was formed by jointly depositing 2mDBTBPDBq-II, PCBBiF and [Ir(tBuppm)2(acac)] in a mass ratio of 0.8:0.2:0.06 (= 2mDBTBPDBq-II: PCBBiF: [Ir(tBuppm)2(acac)]) over the second layer 506(b2') such that it has a thickness of 20 nm.

[0118] The electron transport layer 507 was formed by depositing 2mDBTBPDBq-II in a thickness of 15 nm over each of the light-emitting layers (II) 506b and 506b' and then depositing Bphen (abbreviation) in a thickness of 15 nm.

[0119] The electron injection layer 508 was formed by depositing lithium fluoride (LiF) to a thickness of 1 nm over the electron transport layer 507.

[0120] The second electrode 502 is a cathode electrode formed as follows: Silver (Ag) and magnesium (Mg) were co-deposited in a mass ratio of 1:0.5 to a thickness of 1 nm over the electron injection layer 508, and then silver was deposited to a thickness of 150 nm by sputtering. It should be noted that in all of the preceding evaporation steps, the evaporation was carried out by a resistance heating process.

[0121] Although not in Fig. 5A and Fig.As shown in Figure 5B, the manufactured light-emitting element 1 and the manufactured light-emitting reference element 2 were each sealed in a glove box containing a nitrogen atmosphere in such a way that they were not exposed to air (in particular, a sealant was applied to an outer edge of the light-emitting element, and irradiation with UV light with a wavelength of 365 nm at 6 J / cm² was carried out). 2 carried out, and a heat treatment was performed for 1 hour at 80 °C).

[0122] Table 1 shows the element structures of light-emitting element 1 and light-emitting reference element 2, which were prepared as described above. It should be noted that in Table 1, concerning light-emitting element 1, * 1 the light-emitting layer (I) 506a represents and ∗ 2 , ∗ 3 , ∗ 4 and ∗ 5The first layer 506(b1), the second layer 506(b2), the third layer 506(b3) and the fourth layer 506(b4) respectively represent those contained in the light-emitting layer (II) 506b. Additionally, in Table 1, concerning the light-emitting reference element 2, * 2 , ∗ 6 and ∗ 5 the first layer 506(b1), the second layer 506(b2') or the third layer 506(b3'). [Table 1] first electrode Hole injection layer Hole transport layer Light-emitting layer (I) light-emitting layer (II) Light-emitting element 1 ITO (110 nm) DBT3P-II:MoOx(1:0.5 30 nm) PCPPn(10 nm) ∗ 1 ∗ 2 ∗ 3 ∗ 4 ∗ 5 Light-emitting reference element 2 ∗ 6 ∗ 5 electron transport layer Electron injection layer second electrode 2mDBTBPDBq-II(15 nm) Bphen(15 nm) LiF(1 nm) Mg:Ag(1:0.51 nm) Al(200 nm) ∗ 1 cgDBCzPA : 1,6mMemFLPAPrn (1:0,025 10 nm) ∗ 2 2mDBTBPDBq-II : PCBBiF (0,2:0,8 2 nm) * 3 2mDBTBPDBq-II : PCBBiF : [Ir(tBuppm)2(acac)] (0,1:0,9:0,06 5 nm) * 4 2mDBTBPDBq-II : PCBBiF : [Ir(dmdppr-dmp)2(acac)] (0,1:0,9:0,03 5 nm) * 5 2mDBTBPDBq-II : PCBBiF : [Ir(tBuppm)2(acac)] (0,8:0,2:0,06 20 nm) * 6 2mDBTBPDBq-II : PCBBiF : [Ir(dmdppr-dmp)2(acac)] (0,1:0,9:0,06 5 nm) < <Elementeigenschaften des Licht emittierenden Elementes 1 und des Licht emittierenden Vergleichselementes 2> >

[0123] First, a hemispherical lens with a refractive index of 2.0 was attached to a surface of the substrate of each of the fabricated light-emitting element 1 and light-emitting reference element 2, through which light was to be extracted, using a contact fluid with a refractive index of 1.78. The total luminous flux of each light-emitting element was measured with an integrating sphere at room temperature (in an atmosphere maintained at 25 °C). The results are shown in Table 2. It should be noted that the results shown in Table 2 are initial values ​​of the main properties of light-emitting element 1 and light-emitting reference element 2 at approximately 1000 cd / m². 2 it. [Table 2] Voltage (V) Current(A) Luminous flux (Im) Color coordinates (x,y) Corresponding color temperature (K) Energy efficiency (Im / W) external quantum yield (%) Light-emitting element 1 3,4 0,00015 0,048 (0,49,0,45) 2600 93 43 Light-emitting reference element 2 3,2 0,00015 0,032 (0,41,0,37) 3300 68 34

[0124] The results show that the light-emitting element 1, produced in this example, has a higher external quantum yield than the light-emitting reference element 2. The results also show that the light-emitting element 1 emits light with a most correlated color temperature that falls within the range of the most correlated color temperature of incandescent light (2600 K to 3250 K), which is within the range of most correlated color temperature defined by the Japanese Industrial Standards (JIS) (specifically 2600 K to 7100 K).

[0125] Fig. Figure 6 shows emission spectra in the initial phase, in which the light-emitting element 1 and the light-emitting reference element 2 were operated by a current with a current density of 3.75 mA / cm². 2 was applied to the light-emitting elements. As in Fig.As shown in Figure 6, both light-emitting element 1 and light-emitting reference element 2 exhibit emission peaks at approximately 470 nm, 547 nm, and 613 nm. This suggests that the emission peaks originate from the fluorescence of light-emitting layer (I) 506a and the phosphorescence of light-emitting layers (II) 506b and 506b'.

[0126] It should be noted that the difference between the external quantum yield of light-emitting element 1 and that of light-emitting reference element 2 is likely due to the multilayered structure of the light-emitting layer (II) 506b in light-emitting element 1. This can be suggested by the fact that the intensities of the green and red emissions, which have peaks at approximately 547 nm and 613 nm, are higher in light-emitting element 1 than in light-emitting reference element 2.

[0127] In other words, the light-emitting element 1 was configured such that the third layer 506(b3), formed between the second layer 506(b2) and the fourth layer 506(b4) in the light-emitting layer (II) 506b, emitted light with an emission peak wavelength longer than that of light emitted by the second layer 506(b2) and the fourth layer 506(b4); consequently, the diffusion of excitons formed in the third layer 506(b3) into another layer could be suppressed. This likely resulted in the increased emission efficiency of the light-emitting element 1.

[0128] Furthermore, the reason why the intensity of the blue light with an emission peak at about 470 nm of light-emitting element 1 is lower than that of light-emitting reference element 2 can be explained as follows: Phosphorescence can be efficiently emitted from light-emitting layer (II) 506b for the reason described above, and the probability of energy transfer to light-emitting layer (I) 506a has been reduced.

[0129] As a result, the proportion of phosphorescence in the fluorescence and phosphorescence emissions in light-emitting element 1 was higher than that in light-emitting reference element 2. This likely resulted in the increased external quantum yield of light-emitting element 1.

[0130] Fig. Figure 7 shows the results of a reliability test on the light-emitting element 1. Fig.Figure 7 shows the vertical axis representing the normalized luminance (%), where the initial luminance is 100%, and the horizontal axis representing the operating time (h) of the element. It should be noted that during the reliability test, the light-emitting element 1 was operated under conditions where the initial luminance was set to 5000 cd / m². 2 The current density was set to constant. Reliability test results show that light-emitting element 1 has a long lifetime.

[0131] An element with the same structure as the light-emitting element 1 produced in this example was formed over a substrate with a refractive index of 1.84 such that it had an emission area of ​​90 mm × 90 mm. A surface of the substrate through which light was to be extracted was frosted, thus producing an illumination device with an emission area of ​​90 mm × 90 mm. It should be noted that the thickness of the ITO, which serves as the anode, was set to 70 nm. The produced illumination device exhibited an excellent color rendering index (Ra) of 84 at a luminance of approximately 1000 cd / m². 2 and a very high power efficiency of 92 lm / W. Furthermore, the color temperature of the lighting device was 2800 K, which falls within the defined range of the color temperature of incandescent light. [Example 2]

[0132] In this example, a light-emitting element 3 was fabricated, and its properties were measured. It should be noted that light-emitting element 3 had the same structure as light-emitting element 1 described in Example 1, being, as in Fig.Figure 5A shows that light-emitting layer (I) 506a is a layer that emits fluorescent light, and light-emitting layer (II) 506b is a layer that emits phosphorescent light. Light-emitting layer (II) 506b has a multilayer structure and was configured such that the third layer 506(b3), formed between the second layer 506(b2) and the fourth layer 506(b4), emitted light with an emission peak wavelength longer than that of light emitted by the second layer 506(b2) and the fourth layer 506(b4). The structural formulas and abbreviations of the materials used in this example are shown below. <<Herstellung des Licht emittierenden Elementes 3> >

[0133] The first electrode 501 is an electrode that serves as an anode and was formed as follows: Indium tin oxide containing silicon oxide (ITSO) was deposited by sputtering to a thickness of 70 nm over the glass substrate 500 with a refractive index of 1.84. The electrode area was 81 cm². 2 The process was adjusted. One surface of the substrate, through which light is to be extracted, was matted.

[0134] The manufacturing process and the like of light-emitting element 3, described in this example, are the same as those of light-emitting element 1 and light-emitting reference element 2, which were described in Example 1, with the exception of the electrode area. Table 3 shows an element structure illustrating the properties of light-emitting element 3, a detailed description of which is omitted. It should be noted that fluorescence is obtained from light-emitting layer (I) 506a, and that, as in the case of light-emitting element 1, phosphorescence, which is due to energy transfer from an exciplex, is obtained from the second layer 506(b2), the third layer 506(b3), and the fourth layer 506(b4), respectively, which are contained in light-emitting layer (II) 506b. In Table 3, with respect to light-emitting element 3, * 1the light-emitting layer (I) 506a, and ∗ 2 , ∗ 3 , ∗ 4 and ∗ 5 represent the first layer 506(b1), the second layer 506(b2), the third layer 506(b3) and the fourth layer 506(b4), respectively, which are contained in the light-emitting layer (II) 506b. [Table 3] first electrode Hole injection layer Hole transport layer Light-emitting layer (I) light-emitting layer (II) Light-emitting element 3 ITSO (70 nm) DBT3P-II:MoOx(1:0.5 30 nm) PCPPn(10 nm) ∗ 1 ∗ 2 ∗ 3 ∗ 4 ∗ 5 electron transport layer Electron injection layer second electrode 2mDBTBPDBq-II Bphen(15 nm) (15 nm) LiF(1 nm) Mg:Ag(1:0.51 nm) Ag(150 nm) ∗ 1 cgDBCzPA : 1,6mMemFLPAPrn (1:0,025 10 nm) ∗ 2 2mDBTBPDBq-II : PCBBiF (0,2:0,8 2 nm) * 3 2mDBTBPDBq-II : PCBBiF : [Ir(tBuppm)2(acac)] (0,1:0,9:0,06 5 nm) * 4 2mDBTBPDBq-II : PCBBiF : [Ir(dmdppr-dmp)2(acac)] (0,1:0,9:0,03 5 nm) * 5 2mDBTBPDBq-II : PCBBiF : [Ir(tBuppm)2(acac)] (0,7:0,3:0,06 20 nm) <<Elementeigenschaften des Licht emittierenden Elementes 3> >

[0135] The properties of the fabricated light-emitting element 3 were measured at room temperature (in an atmosphere maintained at 25 °C). The results are presented in Fig. Figure 8 and Table 4 are shown. It should be noted that the results shown in Table 4 are initial values ​​of the main properties of light-emitting element 3 at approximately 1000 cd / m². 2 it. [Table 4] Voltage (V) Current(A) Luminous flux (Im) Color coordinates (x,y) Corresponding color temperature (K) Energy efficiency (Im / W) external quantum yield (%) Light-emitting element 3 3,2 0,09 24 (0,47,0,44) 2800 84 37

[0136] The results show that the light-emitting element 3, produced in this example, has an external quantum yield that is as high as that of the light-emitting element 1 described in Example 1. The results also show that the light-emitting element 3 emits light with a most correlated color temperature that falls within the range of the most correlated color temperature of incandescent light (2600 K to 3250 K), which is within the range of most correlated color temperature defined by the Japanese Industrial Standards (JIS) (specifically 2600 K to 7100 K).

[0137] Fig. Figure 9 shows an emission spectrum in the initial phase, during which the light-emitting element 3 was operated by a current with a current density of 1.2 mA / cm². 2 was applied to the light-emitting element 3. As in Fig.As shown in Figure 9, the light-emitting element 3 exhibits emission peaks at approximately 470 nm, 547 nm, and 613 nm. This suggests that the emission peaks originate from the fluorescence of light-emitting layer (I) 506a and the phosphorescence of light-emitting layer (II) 506b.

[0138] The intensity of the red light, with an emission peak at approximately 613 nm, is much higher than that of the blue light, with an emission peak at approximately 470 nm, of the light-emitting element 3 described in this example. Therefore, the diffusion of excitons formed in the third layer 506(b3), located between the second layer 506(b2) and the fourth layer 506(b4) in the light-emitting layer (II) 506b of the light-emitting element 3, into another layer was suppressed, and the contribution of phosphorescence in the fluorescence and phosphorescence emissions was increased. This likely resulted in the increased external quantum yield. [Example 3]

[0139] In this example, a light-emitting element 4 was fabricated, and its properties were measured. It should be noted that the light-emitting element 4 had the same structure as the light-emitting element 1 described in Example 1, being, as in Fig.Figure 5A shows that light-emitting layer (I) 506a is a layer that emits fluorescent light, and light-emitting layer (II) 506b is a layer that emits phosphorescent light. Light-emitting layer (II) 506b has a multilayer structure and was configured such that the third layer 506(b3), formed between the second layer 506(b2) and the fourth layer 506(b4), emitted light with an emission peak wavelength longer than that of light emitted by the second layer 506(b2) and the fourth layer 506(b4). The structural formulas and abbreviations of the materials used in this example are shown below. <<Herstellung des Licht emittierenden Elementes 4> >

[0140] The first electrode 501 is an electrode that serves as an anode and was formed as follows: Indium tin oxide containing silicon oxide (ITSO) was deposited by a sputtering process to a thickness of 110 nm over a glass substrate 500. The electrode area was set to 2 mm × 2 mm.

[0141] The manufacturing process and the like of light-emitting element 4, described in this example, are the same as those of light-emitting element 1, described in Example 1. Table 5 shows an elemental structure illustrating the properties of light-emitting element 4, the detailed description of which is omitted. It should be noted that in light-emitting element 4, fluorescence is obtained from light-emitting layer (I) 506a, and phosphorescence, which is due to energy transfer from an exciplex, is obtained from the second layer 506(b2), the third layer 506(b3), and the fourth layer 506(b4), respectively, which are contained in light-emitting layer (II) 506b. In Table 5, with respect to light-emitting element 4, * 1 the light-emitting layer (I) 506a, and ∗ 2 , ∗ 3 , ∗ 4 and ∗ 5represent the first layer 506(b1), the second layer 506(b2), the third layer 506(b3) and the fourth layer 506(b4), respectively, which are contained in the light-emitting layer (II) 506b. [Table 5] first electrode Hole injection layer Hole transport layer light-emitting layer (I) light-emitting layer (II) Light-emitting element 4 ITSO (110 nm) DBT3P-II:MoOx (2:1 15 nm) PCPPn (20 nm) * 1 * 2 * 3 * 4 * 5 electron transport layer Electron injection layer second electrode 2mDBTBPDBq-II (15 nm) Bphen (15 nm) LiF (1 nm) Mg:Ag (1:0.5 1 nm) Ag (150 nm) ∗ 1 cgDBCzPA : 1,6mMemFLPAPrn (2:0,05 10 nm) ∗ 2 2mDBTBPDBq-II : PCBBiF (0,4:1,6 2 nm) * 3 2mDBTBPDBq-II : PCBBiF : [Ir(dmppm-dmp)2 (acac)] (0,2:0,8:0,06 5 nm) * 4 2mDBTBPDBq-II : PCBBiF : [Ir(dmdppr-dmp)2 (acac)] (0,3:0,7:0,03 5 nm) * 5 2mDBTBPDBq-II : PCBBiF : [Ir(tBuppm)2 (acac)] (1,6:0,4:0,12 20 nm) <<Elementeigenschaften des Licht emittierenden Elementes 4> >

[0142] The properties of the fabricated light-emitting element 4 were measured at room temperature (in an atmosphere maintained at 25 °C). The results are presented in Fig. Figure 10 and Table 6 are shown. It should be noted that the results shown in Table 6 are initial values ​​of the main properties of light-emitting element 4 at approximately 1000 cd / m². 2 it. [Table 6] Voltage (V) Current(A) Luminous flux (Im) Color coordinates (x,y) Corresponding color temperature (K) Energy efficiency (Im / W) external quantum yield (%) Light-emitting element 4 3,2 0,1 2,6 (0,46,0,45) 3000 41 17

[0143] The results show that the light-emitting element 4, produced in this example, exhibits a high external quantum yield. The results also show that the light-emitting element 4 emits light with a most correlated color temperature that falls within the range of the most correlated color temperature of incandescent light (2600 K to 3250 K), which is within the range of most correlated color temperature defined by the Japanese Industrial Standards (JIS) (specifically, 2600 K to 7100 K).

[0144] Fig. Figure 11 shows an emission spectrum in the initial phase, during which the light-emitting element 4 was operated by a current with a current density of 3.75 mA / cm². 2 was applied to the light-emitting element 4. As in Fig.As shown in Figure 11, the light-emitting element 4 exhibits emission peaks at approximately 469 nm, 550 nm, and 611 nm. This suggests that the emission peaks originate from the fluorescence of light-emitting layer (I) 506a and the phosphorescence of light-emitting layer (II) 506b.

[0145] The intensity of the red light, with an emission peak at approximately 611 nm, is much higher than that of the blue light, with an emission peak at approximately 469 nm, of the light-emitting element 4 described in this example. Therefore, the diffusion of excitons generated in the third layer 506(b3), which was formed between the second layer 506(b2) and the fourth layer 506(b4) in the light-emitting layer (II) 506b of the light-emitting element 4, into another layer was suppressed, and the contribution of phosphorescence in the fluorescence and phosphorescence emissions was increased. This likely resulted in the increased external quantum yield.

[0146] An element with the same structure as the light-emitting element 4 produced in this example was formed over a substrate with a refractive index of 1.84 such that it had an emission area of ​​90 mm × 90 mm. A surface of the substrate through which light was to be extracted was frosted, thus producing an illumination device with an emission area of ​​90 mm × 90 mm. It should be noted that ITO was used as the anode, and the anode thickness was set to 70 nm. The produced illumination device exhibited an excellent color rendering index (Ra) of 83 at a luminance of approximately 1000 cd / m². 2 and a high power efficiency of 81 lm / W. Furthermore, the color temperature of the lighting device was 3200 K, which falls within the defined range of warm white light color temperature. Explanation of reference symbols

[0147] 101: first electrode, 102: second electrode, 103: EL layer, 104: hole injection layer, 105: hole transport layer, 106: light-emitting layer, 106a: light-emitting layer (I), 106b: light-emitting layer (II), 106(b1): first layer, 106(b2): second layer, 106(b3): ​​third layer, 107: electron transport layer, 108: electron injection layer, 201: element substrate, 202: pixel section, 203: driver circuit section (source line driver circuit), 204a and 204b: driver circuit section (gate line driver circuit), 205: sealant, 206: sealant substrate, 207: conductor, 208: flexible printed circuit (FPC), 209: FET 210: FET, 211: Switching FET, 212: Current-controlling FET, 213: First electrode (anode), 214: Insulator, 215: EL layer, 216: Second electrode (cathode), 217: Light-emitting element, 218: Space, 500: Substrate, 501: First electrode, 502: Second electrode, 503: EL layer, 504: Hole injection layer, 505: Hole transport layer506: Light-emitting layer, 506a: Light-emitting layer (I), 506b: Light-emitting layer (II), 506(b1): First layer, 506(b2): Second layer, 506(b3): ​​Third layer, 506(b4): Fourth layer, 506b': Light-emitting layer (II), 506(b2'): Second layer, 506(b3'): Third layer, 507: Electron transport layer, 508: Electron injection layer, 7100: Television set, 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: Keypad, 7205: External Connection port, 7206: Pointing device, 7302: Housing, 7304: Display field, 7305: Icon showing the time, 7306: Other icons, 7311: Control button, 7312: Control button, 7313: Connection port, 7321: Band, 7322: Clasp, 7400: Mobile phone, 7401: Housing, 7402: Display section, 7403: Control button, 7404: External connection port, 7405: Speaker, 7406: Microphone, 7407: Camera,7500(1) and 7500(2): Housing, 7501(1) and 7501(2): First screen, 7502(1) and 7502(2): Second screen, 8001: Lighting device, 8002: Lighting device, 8003: Lighting device and 8004: Lighting device.

Claims

[1] Light-emitting device comprising: a light-emitting layer (106), wherein the light-emitting layer (106) comprises a first layer (106(b1)), a second layer (106(b2)) above the first layer (106(b1)) and a third layer (106(b3)) above the second layer (106(b2)), wherein the second layer (106(b2)) is in contact with the first layer (106(b1)) and the third layer (106(b3)), wherein the first layer (106(b1)), the second layer (106(b2)) and the third layer (106(b3)) each contain a phosphorescent substance, wherein an emission peak wavelength of the second layer (106(b2)) is longer than an emission peak wavelength of the first layer (106(b1)) and / or an emission peak wavelength of the third layer (106(b3)), and wherein the first layer (106(b1)), the second layer (106(b2)) and the third layer (106(b3)) each contain substances that form an exciplex. [2] Light-emitting device comprising: a light-emitting layer (106), wherein the light-emitting layer (106) comprises a first layer (106(b1)), a second layer (106(b2)) above the first layer (106(b1)) and a third layer (106(b3)) above the second layer (106(b2)), wherein the second layer (106(b2)) is in contact with the first layer (106(b1)) and the third layer (106(b3)), wherein at least one of the first layer (106(b1)), the second layer (106(b2)) and the third layer (106(b3)) contains a phosphorescent substance, wherein an emission peak wavelength of the second layer (106(b2)) is longer than an emission peak wavelength of the first layer (106(b1)) and / or an emission peak wavelength of the third layer (106(b3)), and wherein at least one of the first layer (106(b1)), the second layer (106(b2)) and the third layer (106(b3)) contains substances that form an exciplex. [3] Light-emitting device comprising: a layer arrangement consisting of a first light-emitting layer (506a) and a second light-emitting layer (506b), wherein the layer arrangement is located between a pair of electrodes (501; 502), wherein the first light-emitting layer (506a) contains a fluorescent substance, wherein the second light-emitting layer (506b) comprises a first layer (506(b1)), a second layer (506(b2)) above the first layer (506(b1)), a third layer (506(b3)) above the second layer (506(b2)) and a fourth layer (506(b4)) above the third layer (506(b3)), wherein the third layer (506(b3)) is in contact with the second layer (506(b2)) and the fourth layer (506(b4)), wherein the second layer (506(b2)), the third layer (506(b3)) and the fourth layer (506(b4)) each contain a phosphorescent substance, and wherein an emission peak wavelength of the third layer (506(b3)) is longer than an emission peak wavelength of the second layer (506(b2)) and / or an emission peak wavelength of the fourth layer (506(b4)). [4] Light-emitting device comprising: a layer arrangement comprising a first light-emitting layer, a second light-emitting layer, a third light-emitting layer and a fourth light-emitting layer, wherein the layer arrangement lies between a pair of electrodes, wherein the first light-emitting layer contains a fluorescent substance, where the second light-emitting layer overlaps the first light-emitting layer, where the third light-emitting layer overlaps the second light-emitting layer, where the fourth light-emitting layer overlaps the third light-emitting layer, wherein the third light-emitting layer is in contact with the second light-emitting layer and the fourth light-emitting layer, wherein at least one of the second light-emitting layer, the third light-emitting layer and the fourth light-emitting layer contains a phosphorescent substance, and where the emission peak wavelength of the third light-emitting layer differs from the emission peak wavelength of the second light-emitting layer and from the emission peak wavelength of the fourth light-emitting layer. [5] Light-emitting device comprising: a layer arrangement consisting of a first light-emitting layer (506a) and a second light-emitting layer (506b), wherein the layer arrangement is located between a pair of electrodes (501; 502), wherein the first light-emitting layer (506a) contains a fluorescent substance, wherein the second light-emitting layer (506b) comprises a first layer (506(b1)), a second layer (506(b2)) above the first layer (506(b1)), a third layer (506(b3)) above the second layer (506(b2)) and a fourth layer (506(b4)) above the third layer (506(b3)), where the third layer (506(b3)) is in contact with the second layer (506(b2)) and the fourth layer (506(b4)), wherein the second layer (506(b2)), the third layer (506(b3)) and the fourth layer (506(b4)) each contain a phosphorescent substance, and wherein the second layer (506(b2)) and the fourth layer (506(b4)) contain the same substances that form an exciplex. [6] Light-emitting device comprising: a first light-emitting layer (106a) and a second light-emitting layer (106b), wherein the first light-emitting layer (106a) is configured to emit fluorescent light, wherein the second light-emitting layer (106b) is configured to emit phosphorescent light, wherein the second light-emitting layer (106b) comprises a first layer (106(b1), a second layer (106(b2)) above the first layer (106(b1)) and a third layer (106(b3)) above the second layer (106(b2)), wherein the phosphorescent light is a mixture of a first phosphorescent light emitted via energy supplied by a first exciplex in the first layer (106(b1)), a second phosphorescent light emitted via energy supplied by a second exciplex in the second layer (106(b2)), and a third phosphorescent light emitted via energy supplied by a third exciplex in the third layer (106(b3)), where the first phosphorescent light and the second phosphorescent light differ from each other, and where the intensity of the second phosphorescent light is higher than the intensity of the first phosphorescent light and the intensity of the third phosphorescent light.

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