Light-emitting element and light-emitting device

Abstract

To provide a light-emitting element having a structure in which a fluorescence emitting layer and a phosphorescence emitting layer are stacked, and having excellent luminous efficiency.SOLUTION: A light-emitting element includes an EL layer between a pair of electrodes. The EL layer includes a light-emitting layer. The light-emitting layer has at least a multilayer structure in which a first light-emitting layer emitting fluorescence and a second light-emitting layer emitting phosphorescence are in contact. The second layer includes a plurality of layers forming at least an exciplex. The layer forming the exciplex has a multilayer structure in which, between two layers, a layer exhibiting the emission peak longer than the emission peak obtained from the two layers is disposed in contact.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention is a semiconductor device in which an organic compound that emits light when an electric field is applied is disposed between a pair of electrodes. A light-emitting element sandwiched between the light-emitting elements, a light-emitting device having such a light-emitting element, an electronic device, and a lighting device Regarding the device.

[0002] Note that one embodiment of the present invention is not limited to the above technical fields. The technical field of one aspect relates to an article, a method, or a manufacturing method. One aspect of the present invention is a process, machine, manufacture, or composition. Therefore, the invention disclosed herein more specifically relates to The technical field of one aspect of the present invention is a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof, as examples. Some examples include: [Background technology]

[0003] It uses organic compounds as light emitters, which have characteristics such as thinness, light weight, high-speed response, and low DC voltage operation. The light-emitting element is expected to be applied to next-generation flat panel displays. A display device in which light-emitting elements are arranged in a matrix has a longer viewing angle than a conventional liquid crystal display device. It is believed that its advantages lie in its wide angle and excellent visibility.

[0004] The light-emitting mechanism of a light-emitting element is to sandwich an EL layer containing a light-emitting body between a pair of electrodes and apply a voltage. This allows carriers (electrons or holes) to be injected from the electrode, and these carriers then recombine. When the exciton returns to the ground state, it releases energy and emits light. There are two excited states: the singlet excited state (S * ) and triplet excited states (T * ) is known Light emitted from the singlet excited state is called fluorescence, and light emitted from the triplet excited state is called phosphorescence. The statistical generation rate in the light-emitting element is S * :T * =1:3 It is being done.

[0005] In order to improve the device characteristics, it is necessary to consider intersystem crossing (singlet excited state) in such light-emitting devices. Development of light-emitting devices using phosphorescent materials that are prone to transition from a triplet excited state to a triplet excited state Furthermore, in order to obtain white light, different phosphorescent materials are used. A light-emitting device has been disclosed in which layers containing the above are stacked (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-522276 Summary of the Invention [Problem to be solved by the invention]

[0007] In the case of the light-emitting element having the above structure, the stacked light-emitting layers are all light-emitting layers that exhibit phosphorescence (phosphorescence This is because it uses phosphorescence to achieve high luminous efficiency. Not only can it be used as a light-emitting layer that emits fluorescent light (fluorescent light-emitting layer) and a light-emitting layer that emits phosphorescent light, When a layer (phosphorescent light-emitting layer) is laminated, triplet excitons generated in the phosphorescent light-emitting layer diffuse and form triplet After the excitation energy is transferred to the fluorescent layer, it is deactivated, resulting in a significant decrease in luminous efficiency. This is because there is a problem that

[0008] In view of this, in one embodiment of the present invention, a fluorescent-emitting layer and a phosphorescent-emitting layer are stacked. Another embodiment of the present invention provides a light-emitting element having high emission efficiency. Furthermore, one embodiment of the present invention provides a light-emitting device that can achieve low power consumption by applying the above-mentioned To provide an electronic device and a lighting device that can achieve low power consumption by applying a light-emitting element. One embodiment of the present invention is a novel light-emitting element, a novel light-emitting device, a novel lighting device, or the like. The description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily solve all of these problems. The other problems will be obvious from the description, drawings, claims, etc. It is possible to extract other issues from the description, drawings, claims, etc. [Means for solving the problem]

[0009] One embodiment of the present invention includes an EL layer between a pair of electrodes, the EL layer including a light-emitting layer, A laminated structure having a first light-emitting layer that exhibits fluorescent light and a second light-emitting layer that exhibits phosphorescent light is provided. The second light-emitting layer includes at least a plurality of layers that form an exciplex, and the exciplex is The layer to be formed is placed between two layers and has a wavelength longer than the emission peaks obtained from each of the two layers. The light-emitting element is characterized by having a stacked structure in which layers showing different emission peaks are in contact with each other.

[0010] Another embodiment of the present invention is a liquid crystal display device including an EL layer between a pair of electrodes, the EL layer including a light-emitting layer, The light-emitting layer is composed of a first light-emitting layer that emits fluorescent light and a second light-emitting layer that emits phosphorescent light, which are in contact with each other. The second light-emitting layer has at least a laminated structure, and the second light-emitting layer contains a substance that forms an exciplex and a phosphorescent substance. The plurality of layers includes a plurality of layers each including a layer obtained from two layers between two layers. The present invention is characterized in that the layer has a laminated structure in which two layers each exhibiting an emission peak at a wavelength longer than that of the other layer are in contact with each other. It is a light-emitting element.

[0011] Another embodiment of the present invention is a liquid crystal display device including an EL layer between a pair of electrodes, the EL layer including a light-emitting layer, The light-emitting layer is composed of a first light-emitting layer that emits fluorescent light and a second light-emitting layer that emits phosphorescent light, which are in contact with each other. The second light-emitting layer has at least a laminated structure, and the second light-emitting layer contains a substance that forms an exciplex and a phosphorescent substance. and the plurality of layers includes a plurality of layers including: The layers that show emission peaks with wavelengths longer than those obtained from the two layers are adjacent. The light-emitting element is characterized by having a layered structure.

[0012] Another embodiment of the present invention is a liquid crystal display device including an EL layer between a pair of electrodes, the EL layer including a light-emitting layer, The light-emitting layer is composed of a first light-emitting layer that emits fluorescent light and a second light-emitting layer that emits phosphorescent light, which are in contact with each other. The second light-emitting layer has at least a laminated structure, and the second light-emitting layer contains a substance that forms an exciplex and a phosphorescent substance. The plurality of layers each contain one or more common organic compounds. The two layers contain a seed, and between them there is a peak with a wavelength longer than the emission peaks obtained from the two layers. The light-emitting element is characterized by having a stacked structure in which layers showing an emission peak are in contact with each other.

[0013] Another embodiment of the present invention is a liquid crystal display device including an EL layer between a pair of electrodes, the EL layer including a light-emitting layer, The light-emitting layer is composed of a first light-emitting layer that emits fluorescent light and a second light-emitting layer that emits phosphorescent light, which are in contact with each other. The device has at least a laminated structure, and the first light-emitting layer contains a fluorescent light-emitting material, and the second light-emitting layer contains a phosphorescent light-emitting material. The layer containing the phosphorescent material is disposed between two layers. The layer has a laminated structure in which layers that show an emission peak with a wavelength longer than the emission peaks obtained from the respective layers are in contact with each other. The light-emitting device is characterized by:

[0014] Another embodiment of the present invention is a liquid crystal display device including an EL layer between a pair of electrodes, the EL layer including a light-emitting layer, The light-emitting layer is composed of a first light-emitting layer that emits fluorescent light and a second light-emitting layer that emits phosphorescent light, which are in contact with each other. The first light-emitting layer has a laminated structure, and the first light-emitting layer contains a fluorescent light-emitting material and a T1 The second light-emitting layer contains a host material with a low level, and a material that forms an exciplex and a phosphorescent material. and a plurality of layers including: The present invention is characterized by having a laminated structure in which layers exhibiting an emission peak at a wavelength longer than the emission peak are in contact with each other. It is a light emitting element.

[0015] Another embodiment of the present invention is a liquid crystal display device including an EL layer between a pair of electrodes, the EL layer including a light-emitting layer, The light-emitting layer is composed of a first light-emitting layer that emits fluorescent light and a second light-emitting layer that emits phosphorescent light, which are in contact with each other. The first light-emitting layer has a laminated structure, and the first light-emitting layer contains a fluorescent light-emitting material and a T1 The second light-emitting layer contains a host material with a low level, and a material that forms an exciplex and a phosphorescent material. and a plurality of layers including: The area where two layers contact each other and show an emission peak with a wavelength longer than that of the other two layers. The light-emitting element is characterized by having a layer structure.

[0016] Another embodiment of the present invention is a liquid crystal display device including an EL layer between a pair of electrodes, the EL layer including a light-emitting layer, The light-emitting layer is composed of a first light-emitting layer that emits fluorescent light and a second light-emitting layer that emits phosphorescent light, which are in contact with each other. The first light-emitting layer has a laminated structure, and the first light-emitting layer contains a fluorescent light-emitting material and a T1 The second light-emitting layer contains a host material with a low level, and a material that forms an exciplex and a phosphorescent material. The plurality of layers each contain one or more common organic compounds. Between the two layers, there is an emission peak with a wavelength longer than that obtained from each of the two layers. The light-emitting element is characterized by having a stacked structure in which layers showing optical peaks are in contact with each other.

[0017] Another embodiment of the present invention is a liquid crystal display device including an EL layer between a pair of electrodes, the EL layer including a light-emitting layer, The light-emitting layer is composed of a first light-emitting layer that emits fluorescent light and a second light-emitting layer that emits phosphorescent light, which are in contact with each other. The first light-emitting layer has a laminated structure, and the first light-emitting layer contains a fluorescent light-emitting material and a T1 the second light-emitting layer includes a plurality of layers each including a phosphorescent material, and The layer containing the luminescent material has a peak between the two layers that is higher than the peaks of the luminescence obtained from each of the two layers. The light-emitting element is characterized by having a laminated structure in which layers exhibiting a long-wavelength emission peak are in contact with each other. .

[0018] Another embodiment of the present invention is a light-emitting device using a light-emitting element having any of the above structures.

[0019] Furthermore, one embodiment of the present invention is not only a light-emitting device having a light-emitting element, but also an electronic device having a light-emitting device. Therefore, the term "light-emitting device" as used herein also includes a light-emitting device and a lighting device. refers to an image display device or a light source (including lighting equipment). For example, FPC (Flexible printed circuit) or T Module with CP (Tape Carrier Package) attached, TC A module with a printed wiring board at the end of P, or a light emitting element with COG (Chip On Glass) The module, in which the IC (integrated circuit) is directly mounted using the "On Glass" method, is This may be included in the location. [Effects of the Invention]

[0020] According to one embodiment of the present invention, a structure in which a fluorescent-emitting layer and a phosphorescent-emitting layer are stacked is also preferable. Furthermore, one embodiment of the present invention is to provide a light-emitting element that exhibits high emission efficiency. By applying the element, it is possible to provide a light emitting device that realizes low power consumption. One embodiment of the present invention provides an electronic device and a lighting device which use the above light-emitting element and achieve low power consumption. According to one embodiment of the present invention, a novel light-emitting element and a novel light-emitting device can be provided. , or a novel lighting device, etc. can be provided. It is to be noted that one embodiment of the present invention does not necessarily have these effects. It is not necessary for the invention to have all of the above effects. Effects other than these may be included in the specification, drawings, claims, etc. This is self-evident from the description, drawings, claims, etc. It is possible to extract effects other than these. [Brief explanation of the drawings]

[0021] [Figure 1] 1A and 1B illustrate a structure of a light-emitting element according to one embodiment of the present invention. [Figure 2] 1A and 1B illustrate a light-emitting device. [Figure 3] 1A and 1B are diagrams illustrating electronic devices. [Figure 4] 1A and 1B are diagrams illustrating a lighting device. [Figure 5] 1A and 1B illustrate structures of a light-emitting element 1 and a comparative light-emitting element 2. [Figure 6] 10 shows emission spectra of the light-emitting element 1 and the comparative light-emitting element 2. FIG. [Figure 7] FIG. 10 shows the reliability of the light-emitting element 1. [Figure 8] FIG. 10 shows luminance vs. power efficiency characteristics of the light-emitting element 3. [Figure 9] FIG. 10 shows an emission spectrum of the light-emitting element 3. [Figure 10] FIG. 10 shows luminance-current efficiency characteristics of Light-emitting Element 4. [Figure 11] FIG. 10 shows an emission spectrum of the light-emitting element 4. [Figure 12] 1A and 1B are diagrams illustrating the correlation of energy levels in a light-emitting layer. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the form and details thereof may be changed without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the embodiments described below. It is not to be construed as being limited to the

[0023] (Embodiment 1) In this embodiment, a light-emitting element which is one embodiment of the present invention will be described.

[0024] A light-emitting element according to one embodiment of the present invention is formed by sandwiching an EL layer including a light-emitting layer between a pair of electrodes. The light-emitting layer is composed of an emitting layer (I) from which fluorescent light is obtained and an emitting layer (I) from which phosphorescent light is obtained. In this light-emitting element, a charge generation layer (P) is formed between the light-emitting layer (I) and the light-emitting layer (II). Even if no layers are provided (even if it is not a tandem type element), both fluorescent and phosphorescent light can be emitted effectively. Hereinafter, the element structure of the light-emitting element according to one embodiment of the present invention will be described with reference to the accompanying drawings. 1 will be used for a detailed explanation.

[0025] The light-emitting element shown in FIG. 1 has a light-emitting layer between a pair of electrodes (a first electrode 101 and a second electrode 102). The EL layer 103 including the first electrode (anode) 101 is sandwiched between the first electrode (anode) 101 and the second electrode (anode) 102. From the side, a hole injection layer 104, a hole transport layer 105, a light emitting layer 106, an electron The light-emitting layer 106 has a structure in which a transport layer 107, an electron injection layer 108, etc. are laminated in this order. The light-emitting layer (I) 106a and the light-emitting layer (II) 106b are stacked. The order in which the light-emitting layer (I) 106a and the light-emitting layer (II) 106b are stacked is not particularly limited, and any suitable order may be used. This may be changed as appropriate.

[0026] The light-emitting layer (I) 106a contains a fluorescent material and a host material (organic compound). Triplet-triplet annihilation (TTA) is an efficient method for generating triplet excitons from a crystalline material. By using the ion-triplet annihilation (ET-triplet annihilation), the singlet excitons are converted to and the fluorescent substance emits light by energy transfer from the singlet exciton. do.

[0027] Specifically, the T1 level (lowest triplet excitation energy) of the host material in the light-emitting layer (I) 106a It is preferable that the T1 level of the fluorescent material is lower than the T1 level of the fluorescent material. The abundance ratio of the host material is overwhelmingly higher. By using them in combination so that the T1 level is lower than that of the emitting layer (I) 106a, The triplet excitons are converted into the fluorescent material ( The probability of triplet excitons colliding with each other is reduced due to the triplet excitons being trapped and localized in the molecule. This prevents the occurrence of TTA and increases the probability of TTA occurring. The luminous efficiency of the fluorescent light emitted from the light-emitting layer (I) 106a can be improved. As the fluorescent material, known materials can be used, and the emitted light color is blue (for example, having an emission spectrum peak between 400 nm and 480 nm), green (e.g., 5 red (e.g., having an emission spectrum peak between 5800 nm and 560 nm); 0 nm to 680 nm), orange, yellow, etc., as appropriate. It shall be possible to use it.

[0028] The light-emitting layer (II) 106b includes a structure in which at least three different layers are stacked, each of which is As shown in FIG. 1, the first layer 106(b1), the second layer 106(b2), the third layer 106(b3), 6(b3). All three of these layers form exciplexes. Each layer contains two types of organic compounds that can be synthesized and a phosphorescent material. The emission wavelength of the formed exciplex is the emission wavelength of each organic compound that forms the exciplex. (fluorescence wavelength), these fluorescence spectra are on the longer wavelength side. This allows for a reduction in the driving voltage. In addition, energy can be transferred from the exciplex to the phosphorescent material, resulting in high luminescence. In addition to the above three layers, the light-emitting layer (II) 106b also includes: It may also have a layer made of an organic compound that does not contain a phosphorescent material.

[0029] Furthermore, the above three layers have the same emission peak of phosphorescence obtained from the second layer 106(b2). are the phosphorescent emission peaks of the first layer 106(b1) and the third layer 106(b3). The wavelength is formed to be longer than that of the peak.

[0030] Specifically, the second phosphorescent material used in the second layer 106(b2) is the same as that used in the first layer 106( b1) and the third phosphorescent material used in the third layer 106 (b3). A substance having an emission peak at a wavelength longer than that of the light-emitting layer (II) 1 is used. The phosphorescent materials used in these three layers of the optical film 06b may be known materials. The emission color is blue (e.g., emission spectrum between 400 nm and 480 nm). green (e.g., with an emission spectrum between 500 nm and 560 nm) red (e.g., with an emission spectrum between 580 nm and 680 nm) Peak), orange, yellow, etc., which can be used appropriately according to the above configuration Let's say.

[0031] By using such a structure for the light-emitting layer (II) 106b, the second layer 106( In the second layer 106 (b2), the emission peak from the exciplex generated in the second layer 106 (b2) is the longest. This allows for efficient energy transfer to the phosphorescent material, which has a wavelength similar to that of the other layers. Since the diffusion of excitons can be suppressed, the luminous efficiency of phosphorescence in the light-emitting layer (II) 106b can be increased. The light-emitting layer (II) 106b is formed only from the above-mentioned three layers. There are two types of organic compounds that can form exciplexes without phosphorescent materials. It may further have a layer containing a compound.

[0032] In the light-emitting layer (I) 106a and the light-emitting layer (II) 106b, a fluorescent material or a phosphorescent material In addition, the organic compounds used as host materials are mainly 10 -6 cm 2 / Vs or more electron transporting materials with electron mobilities of 10 -6 cm 2 Hole transfer above / Vs However, the phosphorescent light-emitting layer (II) 106b may be a hole-transporting material having a high conductivity. In the layer containing the substance, a combination of the above organic compounds capable of forming an exciplex is used for each layer. Two or more types of combinations shall be used.

[0033] In addition, in the light-emitting layer (I) 106a and the light-emitting layer (II) 106b, a light-emitting material (a fluorescent material) By dispersing the organic compound (such as a phosphorescent material) in the light-emitting layer, In addition, it is possible to suppress the crystallization in the luminescent material. This can suppress the emission of light and increase the luminous efficiency of the light-emitting element.

[0034] In the light-emitting layer (II) 106b, the T1 level of the organic compound is It is preferable that the T1 level of the electron transport material or hole transport material is higher than the T1 level of the material. If the triplet excitation energy of the phosphorescent material is lower than the T1 level of the phosphorescent material, the triplet excitation energy of the phosphorescent material that contributes to the emission The electron transport material and hole transport material quench the light, resulting in a decrease in luminous efficiency. This is to invite

[0035] By fabricating a light-emitting device that satisfies the above conditions, it is possible to obtain fluorescent and phosphorescent light. Furthermore, a light-emitting element can be obtained that emits fluorescent light using the above-mentioned materials. The light-emitting layer (I) 106a from which phosphorescence is obtained and the light-emitting layer (II) 106b from which phosphorescence is obtained are respectively The combination of luminescent colors obtained (luminescent colors obtained from the luminescent layer (I) 106a and the luminescent layer (II) The emission color obtained by 106b is shown as "blue, green, red, green" for example. , "Blue\Blue·Red·Green", "Blue\Yellow·Red·Green", "Blue\Green·Red·Yellow" Color", "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 Examples include "red-green-red-yellow" and "red-yellow-red-yellow". In addition, the stacking relationship between the light-emitting layer (I) 106a and the light-emitting layer (II) 106b is reversed. Similar combinations are possible when

[0036] Generally, when a light-emitting layer that produces fluorescence and a light-emitting layer that produces phosphorescence are laminated, a phosphorescent light-emitting layer The triplet excitation energy generated in the fluorescent layer is transferred to the host material and non-radiatively deactivated. However, the light-emitting diodes shown in one embodiment of the present invention can be used to reduce the light-emitting efficiency. The device converts triplet excitation energy from the exciplex formed in the phosphorescent emitting layer into the phosphorescent material. The structure is such that light is emitted by the transfer of excitons from the exciplex to a region other than the phosphorescent material. In principle, this is a situation where diffusion is difficult to occur, so not only fluorescent emission but also phosphorescent emission can be obtained efficiently. However, in one embodiment of the present invention, in the light-emitting layer (I) 106a, Since the light-emitting layer (II) 106 has a structure that can easily generate a singlet excited state, Even if there is a transfer of triplet excitation energy from the exciplex formed in b, It can be converted into fluorescent light.

[0037] FIG. 12 shows a correlation diagram of the energy levels of each substance and exciplex in the light-emitting element. S FH is the singlet excitation level of the host material in the light-emitting layer (I) 106a, T FH is the light-emitting layer ( I) Triplet excited level of the host material in 106a, S FG In the light-emitting layer (I) 106a The singlet excited level of the guest material (fluorescent material) in the FG In the light-emitting layer (I) 106a The triplet excited state of the guest material (fluorescent material) in the PH is in the light-emitting layer (II) 106b. The singlet excited level of the host material (the first organic compound or the second organic compound) in the PH is the host material (first organic compound or second organic compound) in the light-emitting layer (II) 106b ) triplet excited level, S E is the singlet excited level of the exciplex in the light-emitting layer (II) 106b. , T E is the triplet excited level of the exciplex in the light-emitting layer (II) 106b, T PG is the light-emitting layer (II) The triplet excitation level of the guest material (phosphorescent material) in 106b.

[0038] As shown in FIG. 12, in the light-emitting layer (I) 106a, triplet excited molecules of the host material collide with each other, and This causes TTA, converting some of the triplet excited molecules of the host material into singlet excited molecules. (Part of it is thermally deactivated). Then, the singlet excited state ( S FH ) is converted into the singlet excited state (S FG ) and then The energy is converted into fluorescence.

[0039] In the light-emitting layer (II) 106b, the excitation level (S E , T E ) is the host material The excited levels (S PH , T PH ) Therefore, the excitation energy does not transfer from the exciplex to the host material. However, the excitation energy of the exciplex does not transfer from the exciplex to another exciplex. When the ions move to the guest material (phosphorescent material), they can be converted into light. In the light-emitting layer (II) 106b, there is almost no diffusion of triplet excitation energy, and light is emitted. can be converted to

[0040] Therefore, the energy at the interface where the light-emitting layer (I) 106a and the light-emitting layer (II) 106b are in contact with each other is Even if there is some movement (for example, the T of the phosphorescent material present at the interface), PG From T FH and T FG (energy transfer to the light-emitting layer (I) 106a and the light-emitting layer (II) 106b) In addition, in the light-emitting layer (I) 106a, The triplet excitation energy of TTA generates a singlet excited state, which causes Even if energy transfer occurs in the fluorescein, part of it is converted into fluorescence. It is possible to suppress energy loss.

[0041] Next, a specific example of fabricating the above light-emitting device will be described.

[0042] The first electrode (anode) 101 and the second electrode (cathode) 102 are made of a metal, an alloy, an electrically conductive material, or the like. In particular, indium oxide, Indium tin oxide, silicon or silicon oxide containing Indium oxide-tin oxide, Indium oxide-zinc oxide (Indium Zinc Oxide) ide), 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), titanium (Ti) In addition to these, elements belonging to Groups 1 and 2 of the periodic table, such as lithium (Li) and cesium (Ce), Alkali metals such as cesium (Cs), calcium (Ca), strontium (Sr), etc. Alkaline earth metals, magnesium (Mg), and alloys containing these (MgAg, Al rare earth metals such as Li, europium (Eu), ytterbium (Yb) and The first electrode (anode) 101 may be an alloy containing graphene or the like. The second electrode (cathode) 102 is formed by, for example, sputtering or vapor deposition (including vacuum deposition). It can be formed by, for example,

[0043] 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. This is a layer for injecting holes, and contains a hole transporting material and an acceptor material. By including a hole transporting material and an acceptor material, the acceptor material can transfer electrons from the hole transporting material. The electrons are extracted, generating holes, which are transported to the light-emitting layer 106 via the hole transport layer 105. Holes are injected into the hole transport layer 105. The hole transport layer 105 is formed using a hole transport material.

[0044] Examples of hole transport materials used in the hole injection layer 104 and the hole transport layer 105 include: ,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD) and 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]tri Phenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-biphenylamine)] Aromatic compounds such as [fluoren-2-yl]-N-phenylamino]biphenyl (abbreviation: BSPB) Aromatic amine compound, 3-[N-(9-phenylcarbazol-3-yl)-N-phenyl amino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-( 9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazol (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbamoyl) [(3-phenylcarbazole-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), etc. Other examples include 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP) , 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB ), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazo Carbazole derivatives such as CzPA (abbreviation: CzPA) can be used. The substance is mainly 10 -6 cm 2 A material with a hole mobility of 1 / Vs or more. Any substance other than these may be used as long as it has a higher hole transporting property than the above.

[0045] Furthermore, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenyl ether) Nylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenyl amino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide]( abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis (phenyl)benzidine (abbreviated as Poly-TPD) It is also possible.

[0046] The acceptor material used in the hole injection layer 104 is selected from the group consisting of the 4th group of the periodic table of elements. Examples of the oxides of metals belonging to Groups 1 to 8 include molybdenum oxide. is particularly preferred.

[0047] The light-emitting layer 106 is a layer in which a light-emitting layer (I) 106a and a light-emitting layer (II) 106b are laminated. The configuration of these layers is as described above.

[0048] The fluorescent material used in the light-emitting layer (I) 106a is a material that emits the following singlet excitation energy: There are substances that can be converted into light.

[0049] For example, N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N' -Diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-calcium (bazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (Abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-di N,9-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA) Phenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazo perylene, 2,5,8,11-tetra-(tetramethylbenzophenone) rt-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)- 4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: P CBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi -4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenedia N,9-diphenyl-N-[4-(9,10-diphenylamine)] (abbreviation: DPABPA), [(2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviated as 2PCAP) PA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N', N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N, N',N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p] Chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N- (9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole -3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl- 2-yl)-2-anthryl]-N,9-diphenyl-9H-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-carbazole-9-yl)] phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Kumari N,N'-diphenylquinacridone, (abbreviation: DPQd), rubrene, 5, 12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation Name: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6- Methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{ 2-Methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij] Quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene N,N,N-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-1H,5H-benzo[ ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanediyl tolyl (abbreviation: DCJTI), {2-tert-butyl-6-[2-(1,1,7,7- Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine -9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: D CJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl} -4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2 ,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetramethyl- tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pi {ran-4-ylidene}propanedinitrile (abbreviation: BisDCJ™) In particular, pyrenediamines such as 1,6FLPAPrn and 1,6mMemFLPAPrn Condensed aromatic diamine compounds, which are typified by compounds such as phthalocyanine, have high hole trapping properties and high luminous efficiency. This is preferable because of its excellent reliability.

[0050] The phosphorescent material used in the light-emitting layer (II) 106b is selected from the group consisting of: There are substances that can turn ghee into luminescence.

[0051] For example, bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato- N,C 2’}Iridium(III) picolinate (abbreviation: Ir(CF3ppy)2(pi c)), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]Ili Dium(III) acetylacetonate (abbreviation: FIracac), tris(2-phenyl) Ir(ppy)3, bis(2-phenyl) pyridinato)iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(a cac)), tris(acetylacetonato)(monophenanthroline)terbium(II I) (abbreviation: Tb(acac)3(Phen)), bis(benzo[h]quinolinato)yl Ir(bzq)2(acac) (2,4-diphenyl-1,3-oxazolato-N,C 2’ ) Iridium(III) acetone Ir(dpo)2(acac)), bis{2-[4'-(per Fluorophenyl)phenyl]pyridinato-N,C 2’}Iridium(III) acetyl Acetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzyl) N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir (bt)2(acac)), bis[2-(2'-benzo[4,5-α]thienyl)pyridin Nat-N,C 3’ ]Iridium(III) acetylacetonate (abbreviation: Ir(btp) 2(acac)), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium (II I) acetylacetonate (abbreviation: Ir(piq)2(acac)), (acetylacetonate Nato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(II I) (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- methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iP r)2(acac)]), (acetylacetonato)bis(2,3,5-triphenylpyrrolidone) dinato)iridium(III) (abbreviation: Ir(tppr)2(acac)), bis(2, 3,5-triphenylpyrazinate)(dipivaloylmethanato)iridium(III)(abbreviation Name: [Ir(tppr)2(dpm)]), (acetylacetonato)bis(6-tert -butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBup pm)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinyl) Nat(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-propanedionato) )(monophenanthroline)europium(III) (abbreviation: Eu(DBM)3(Phe n)), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](mono Phenanthroline) europium(III) (abbreviation: Eu(TTA)3(Phen)) Examples include:

[0052] In place of the phosphorescent material, a thermally activated delayed fluorescence (TADF) ) materials can also be used. Note that delayed fluorescence in TADF materials is different from normal fluorescence. It is a type of luminescence that has a similar spectrum but has a significantly longer lifetime. -6 seconds More than 10, preferably -3 More than a second.

[0053] Specific examples of TADF materials include fullerenes and their derivatives, and aldehydes such as proflavine. These include chloridine derivatives, eosin, etc. Also, magnesium (Mg), zinc (Zn) , cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or Examples of metal-containing porphyrins include those containing radium (Pd). Examples of the fluorine-containing compounds include protoporphyrin-tin fluoride complex (SnF2 (Proto IX )), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematopor Hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrinte tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), Octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin -Tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride Furthermore, 2-(biphenyl-4-yl)-4 ,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1, π-electron rich heteroaromatic rings such as 3,5-triazine (PIC-TRZ) and π-electron deficient heteroaromatic rings A heterocyclic compound having a π-electron-rich heteroaromatic ring can also be used. The substance in which the π-electron-deficient heteroaromatic ring is directly bonded exhibits the donor property of the π-electron-rich heteroaromatic ring. The acceptor properties of the π-electron-deficient heteroaromatic rings are both strong, and the energy difference between S1 and T1 is This is particularly preferable because it is small.

[0054] The organic compound used in the light-emitting layer (I) 106a is 9-phenyl-3-[4-(10- Phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3 -[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: P CPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-cal CzPA (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), 9-phenyl-10-{4-(9-phenyl-9 H-fluoren-9-yl)-biphenyl-4'-yl}anthracene (abbreviation: FLPP A) and other anthracene compounds. When used as a light-emitting material, it is possible to realize a light-emitting layer with good luminous efficiency and durability. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA have very good characteristics. It is preferable because it indicates sex.

[0055] The electron transporting organic compound used in the light-emitting layer (II) 106b is a nitrogen-containing heterocyclic compound. π-electron deficient heteroaromatic compounds such as aromatic compounds are preferred, for example, 2-[3-( Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2 mDBTPDBq-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-(dibenzothiophene) phen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPD Bq-II) and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo [f,h]quinoxaline (abbreviation: 6mDBTPDBq-II) or Dibenzoquinoxaline derivatives are included.

[0056] The hole transport material, which is an organic compound used in the light-emitting layer (II) 106b, is a π-electron Electron-rich heteroaromatic compounds (e.g., carbazole derivatives and indole derivatives) and aromatic aromatic compounds Preferred are amine compounds, such as 4-phenyl-4'-(9-phenyl-9H-carbazoline). 4,4'-di(1-naphthyl-3-yl)triphenylamine (abbreviation: PCBA1BP), (9-phenyl-9H-carbazol-3-yl)triphenylamine PCBNBB, 3-[N-(1-naphthyl)-N-(9-phenylcarbazoline] (3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), 4, 4',4''-Tris[N-(1-naphthyl)-N-phenylamino]triphenylamine 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-diphenylamine) N,N',amino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF) N''-triphenyl-N,N',N''-tris(9-phenylcarbazole-3-yl) 2-[N-(9-phenyl)benzene-1,3,5-triamine (abbreviation: PCA3B) 1,2-Dimethylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene( Abbreviation: PCASF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino] N,N'-bis[4-(carbonyl) [N,N'-diphenyl-9,9-dimethylfluorene]-N,N'-diphenyl-9,9-dimethylfluorene 4,4'-bis[N-(3-methylphenyl)-2,7-diamine (abbreviation: YGA2F) 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-phenylcarbazol PCzPCA1, 3-[N-(4-diphenylaminophenyl)-N- Phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis [N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarba PCzDPA2, 4,4'-bis(N-[4-[N'-(3-methylphenyl) (phenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation :DNTPD), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-na butyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 3,6-bis [N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenyl Carbazole (abbreviation: PCzPCA2) is an example.

[0057] The electron transport layer 107 is a layer containing a substance with a high electron transport property. lq3, tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq3), Bis(10-hydroxybenzo[h]quinolinato)beryllium (BeBq2), B Alq, Zn(BOX)2, bis[2-(2-hydroxyphenyl)benzothiazolato] Metal complexes such as zinc (abbreviated as Zn(BTZ)2) can be used. -biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazo PBD, 1,3-bis[5-(p-tert-butylphenyl)-1,3 ,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 3-(4-ter t-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triacontria TAZ (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)- p-EtTA Z), bathophenanthroline (abbreviated as Bphen), bathocuproine (abbreviated as BCP) , 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: Bz Heteroaromatic compounds such as poly(2,5-pyridinediamine) and poly(2,5-pyridinediamine) can also be used. yl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)- co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), poly[(9,9-dioctadecyl) (2,2'-bipyridine-6,6'-diyl)-co-(2,2'-bipyridine-2,7-diyl) )] (abbreviation: PF-BPy) can also be used. The substance is mainly 1×10 -6 cm 2 It is a substance with an electron mobility of 1 / Vs or more. Any substance other than those mentioned above can be used as the electron transport layer 107 as long as it has a higher electron transporting property than hole transporting property. It's fine.

[0058] The electron transport layer 107 may be a single layer or may be a laminate of two or more layers made of the above-mentioned materials. It may also be the same as the above.

[0059] The electron injection layer 108 is a layer containing a substance with high electron injection properties. Lithium fluoride (LiF), Cesium fluoride (CsF), Calcium fluoride (CaF2), Lithium oxide (LiO x ) and the like, alkali metals, alkaline earth metals, or Compounds such as erbium fluoride (ErF3) can also be used. Furthermore, an electride may be used for the electron injection layer 108. The electride may be, for example, a mixed oxide of calcium and aluminum with electrons. The material constituting the electron transport layer 107 may be a material containing a high concentration of can also be used.

[0060] In addition, the electron injection layer 108 may contain a composite material formed by mixing an organic compound and an electron donor (donor). Such composite materials are formed by electron donors generating electrons in organic compounds. In this case, the organic compound is: It is preferable that the material has excellent transport properties for the generated electrons. Specifically, for example, the above-mentioned The substance constituting the electron transport layer 107 (metal complex, heteroaromatic compound, etc.) can be used. The electron donor may be any substance that exhibits electron donating properties to organic compounds. The metals are preferably alkali metals, alkaline earth metals, or rare earth metals, and more preferably lithium, cesium, magnesium, or the like. Examples of the metals include magnesium, calcium, erbium, and ytterbium. Metal oxides and alkaline earth metal oxides are preferred, and lithium oxide, calcium oxide, Examples of the base include barium oxide. In addition, a Lewis base such as magnesium oxide can be used. It is also possible to use organic compounds such as tetrathiafulvalene (TTF). It is also possible.

[0061] The hole injection layer 104, the hole transport layer 105, and the light-emitting layer 106 (light-emitting layer (I) 10) 6a), the light-emitting layer (II) 106b), the electron transport layer 107, and the electron injection layer 108 are respectively It can be formed by a deposition method (including a vacuum deposition method), an inkjet method, a coating method, etc. do.

[0062] The light-emitting element described above emits light due to a potential difference generated between the first electrode 101 and the second electrode 102. Carriers are injected from the EL layer 103, and holes and electrons are recombined in the EL layer 103, resulting in light emission. This light emission is transmitted to either the first electrode 101 or the second electrode 102. Therefore, the electric current is taken out through the first electrode 101 and the second electrode 102. Either one or both of the electrodes 02 is a light-transmitting electrode.

[0063] As described above, by forming a light emitting element having the structure described in this embodiment mode, fluorescent light and In a light-emitting element that can emit phosphorescence, the luminous efficiency of the phosphorescence is particularly increased, and the entire light-emitting element As a result, a light-emitting element with high luminous efficiency can be obtained.

[0064] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. It shall be possible to do so.

[0065] (Embodiment 2) In this embodiment, an example of a light-emitting device including a light-emitting element according to one embodiment of the present invention will be described. An active matrix light-emitting device will be described with reference to FIG. The light-emitting element described in Embodiment 1 can be applied to the light-emitting device.

[0066] 2A is a top view showing the light emitting device, and FIG. 2B is a top view showing the light emitting device along the dashed line AA in FIG. 2A. 1 is a cross-sectional view taken along the line '. A pixel section 202 and a driving circuit section (source line driving circuit) 203 are provided on an element substrate 201. and driver circuit sections (gate line driver circuits) 204a and 204b. The drive circuit section 203 and the drive circuit sections 204a and 204b are sealed by a seal material 205. The element substrate 201 is sealed between the element substrate 201 and the sealing substrate 206 .

[0067] Also, on the element substrate 201, a driving circuit section 203, and driving circuit sections 204a and 204b are provided. external signals (e.g., video signals, clock signals, start signals, or reset signals) A wiring 207 is provided for connecting an external input terminal for transmitting a signal or potential. Here, an FPC (flexible printed circuit) 208 is set as the external input terminal. Although only the FPC is shown here, this FPC also has a plug. A printed wiring board (PWB) may be attached. This includes not only the light-emitting device itself, but also the state in which an FPC or PWB is attached to it. It shall be.

[0068] Next, the cross-sectional structure will be described with reference to FIG. and a pixel portion are formed, but here, a driver circuit portion 203 which is a source line driver circuit and , a pixel portion 202 is shown.

[0069] The driving circuit section 203 is exemplified by a configuration in which an FET 209 and an FET 210 are combined. The FET 209 and the FET 210 included in the driving circuit unit 203 are unipolar (N-type or It may be formed of a circuit including only N-type or P-type transistors. It may be formed of a CMOS circuit including a P-type transistor and a P-type transistor. In the embodiment, a driver integrated type in which a drive circuit is formed on a substrate is shown, but this is not necessarily required. It is not necessary to form the driving circuit on the substrate, but it is also possible to form the driving circuit externally.

[0070] The pixel section 202 includes a switching FET 211, a current control FET 212, and a current control FET 213. A first electrode electrically connected to the wiring (source electrode or drain electrode) of the control FET 212 The pixel electrode (anode) 213 is formed by a plurality of pixels. The pixel is formed by two FETs, a switching FET 211 and a current control FET 212. However, the present invention is not limited to this. For example, the present invention may be applied to a case where three or more FEs are configured. The pixel portion 202 may be a combination of T and a capacitance element.

[0071] The FETs 209, 210, 211, and 212 may be, for example, staggered or inverted staggered transistors. Transistors can be applied to FETs 209, 210, 211, and 212. Examples of semiconductor materials that can be used include Group IV (silicon, etc.) semiconductors, Group III (gallium, Semiconductors, compound semiconductors, oxide semiconductors, and organic semiconductor materials can be used. The crystallinity of the semiconductor material is not particularly limited, and may be, for example, an amorphous semiconductor or a crystalline semiconductor. In particular, FETs 209, 210, 211, and 212 can be made of crystalline semiconductors. It is preferable to use an oxide semiconductor. As the oxide semiconductor, for example, an In-Ga oxide oxides, In-M-Zn oxides (M is Al, Ga, Y, Zr, La, Ce, or Nd) The FETs 209, 210, 211, and 212 may be, for example, energy gates. Oxides with a gap of 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more By using a semiconductor material, the off-state current of a transistor can be reduced.

[0072] An insulator 214 is formed to cover the end of the first electrode 213. The object 214 is formed by using a positive photosensitive acrylic resin. In this embodiment, the first electrode 213 is used as an anode.

[0073] In addition, the upper or lower end of the insulator 214 is formed with a curved surface. By forming the shape of the insulator 214 as described above, the upper layer of the insulator 214 is For example, the material of the insulator 214 can be Either a negative photosensitive resin or a positive photosensitive resin can be used. Not only organic compounds but also inorganic compounds, such as silicon oxide, silicon oxynitride, silicon nitride, etc. Cone etc. can be used.

[0074] An EL layer 215 and a second electrode (cathode) 216 are stacked on the first electrode (anode) 213. The EL layer 215 is provided with at least a light-emitting layer. It has the laminated structure described in the embodiment 1. In addition to the light-emitting layer, the EL layer 215 also has 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 as appropriate.

[0075] The first electrode (anode) 213, the EL layer 215, and the second electrode (cathode) 216 are laminated together. The light emitting element 217 is formed by the structure. The material used for the second electrode (cathode) 216 is the material shown in Embodiment 1. Although not shown here, the second electrode (cathode) 216 is an external input terminal. It is electrically connected to an FPC 208.

[0076] In addition, although only one light-emitting element 217 is shown in the cross-sectional view of FIG. 2B, the pixel portion 2 In the device 02, a plurality of light-emitting elements including a light-emitting element according to one embodiment of the present invention are arranged in a matrix. The pixel section 202 emits three types of light (R, G, B). and forming a light-emitting device capable of full-color display by selectively forming light-emitting elements to be used. In addition to light-emitting elements that can emit three types of light (R, G, B), Light-emitting elements that emit light such as white (W), yellow (Y), magenta (M), and cyan (C) For example, a light emitting element that can emit three kinds of light (R, G, B) may be formed by By adding light-emitting elements that can emit several types of light, color purity can be improved and power consumption can be reduced. In addition, in order to narrow the line width of each luminescent color, the resonance of light between the electrodes is It may also be configured to have a micro-optical resonator (microcavity) structure that utilizes the effect. In addition, by combining it with a color filter, it can be used as a light-emitting device capable of full-color display. Furthermore, a light-emitting element having a tandem structure may be used as the light-emitting element according to one embodiment of the present invention. An optical element may also be applied.

[0077] Furthermore, by bonding the sealing substrate 206 to the element substrate 201 with the sealing material 205, A space 218 surrounded by the element substrate 201, the sealing substrate 206, and the sealant 205 contains a light-emitting element. The space 218 is filled with an inert gas (nitrogen or argon). The present invention also includes a configuration in which the cavity is filled with a sealing material 205, in addition to a configuration in which the cavity is filled with a gas such as argon.

[0078] It is preferable to use epoxy resin or glass frit for the sealing material 205. It is desirable that these materials be as impermeable to moisture and oxygen as possible. Materials used for the sealing substrate 206 include glass substrates, quartz substrates, and FRP (Fiber-Reinforced Plastics). reinforced plastics), PVF (polyvinyl fluoride), polyester A plastic substrate made of polyethylene or acrylic can be used as a sealing material. When glass frit is used, the element substrate 201 and the sealing substrate 206 are is preferably a glass substrate.

[0079] In this manner, an active matrix light emitting device can be obtained. In the embodiment, an active matrix light emitting device will be described as an example of the light emitting device. However, a passive matrix to which the light-emitting element according to one embodiment of the present invention described in Embodiment 1 is applied is also used. It is also possible to fabricate a light-emitting device of a risk type.

[0080] In the case of an active matrix light emitting device, the structure of the transistor (FET) The structure is not particularly limited. For example, a staggered or inverted staggered FET can be used as appropriate. In addition, the drive circuit formed on the FET substrate can be divided into N-type and P-type FETs. Alternatively, it may be composed of only one of N-type FETs or P-type FETs. Furthermore, there is no particular limitation on the crystallinity of the semiconductor film used in the FET. For example, an amorphous semiconductor film or a crystalline semiconductor film can be used. Materials include group IV (silicon, etc.) semiconductors, group III (gallium, etc.) semiconductors, and compound semiconductors. In addition to semiconductors (including oxide semiconductors), organic semiconductors and the like can also be used.

[0081] Note that the structure shown in this embodiment mode may be used in appropriate combination with structures shown in other embodiment modes. It is possible.

[0082] (Embodiment 3) In this embodiment, a light-emitting device manufactured using a light-emitting element according to one embodiment of the present invention is used. An example of various electronic devices completed using this method will be described with reference to FIG. 3.

[0083] As an electronic device to which a light emitting device is applied, for example, a television set (television or television (also called television receivers), computer monitors, digital cameras, digital video Cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), mobile phones These include portable game machines, mobile information terminals, sound reproduction devices, and large game machines such as pachinko machines. Specific examples of these electronic devices are shown in Figure 3.

[0084] FIG. 3A shows an example of a television device. The television device 7100 is A display unit 7103 is built into the body 7101. The display unit 7103 displays images. The light-emitting device can be used for the display portion 7103. 7, a configuration in which a housing 7101 is supported by a stand 7105 is shown.

[0085] The television device 7100 can be operated using an operation switch provided on the housing 7101 or a separate remote control. This can be done using the remote control operation device 7110. The channel and volume can be controlled by the 7109, and the information displayed on the display 7103 is In addition, the remote control unit 7110 can be used to operate the video. A display unit 7107 for displaying information output from 7110 may be provided.

[0086] The television device 7100 is configured to include a receiver, a modem, etc. It is possible to receive more general television broadcasts, and also to receive them by wire or wirelessly via a modem. By connecting to a communication network, it can be transmitted in one direction (sender to receiver) or two directions (transmit to receiver). It is also possible to communicate information between followers and recipients, or between recipients themselves.

[0087] FIG. 3B shows a computer, which includes a main body 7201, a housing 7202, a display unit 7203, and a keyboard. It includes a board 7204, an external connection port 7205, a pointing device 7206, and the like. Note that the computer can be manufactured by using a light-emitting device in the display portion 7203. can be done.

[0088] FIG. 3C shows a smartwatch, which includes a housing 7302, a display panel 7304, and operation buttons. The connectors 7311, 7312, the connection terminal 7313, the band 7321, the clasp 7322, etc. do.

[0089] A display panel 7304 mounted on a housing 7302 that also serves as a bezel has a non-rectangular display area. The display panel 7304 displays an icon 7305 that indicates the time, other icons, It is possible to display 7306 etc.

[0090] The smartwatch shown in FIG. 3C can have various functions. For example, , the function to display various information (still images, videos, text images, etc.) on the display, Functions such as calendar, date or time display, various software (programs) It has the functions of controlling processing by wireless communication, and It has the function of connecting to a data network, and the function of transmitting or receiving various data using wireless communication. The function of reading out the program or data recorded on the recording medium and displaying it on the display unit. It can have functions such as:

[0091] In addition, a speaker, a sensor (force, displacement, position, velocity, acceleration, angular velocity) Degrees, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, electricity Includes functions to measure pressure, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared. The smart watch may have a light emitting device, a microphone, etc. The display panel 7304 can be manufactured by using the same.

[0092] FIG. 3(D) shows an example of a mobile phone (including a smartphone). 400 includes a housing 7401, a display unit 7402, a microphone 7406, a speaker 7405, a camera, and the like. The device is equipped with a camera 7407, an external connection section 7404, and operation buttons 7403. When a light-emitting element according to one embodiment of the present invention is formed over a flexible substrate, as shown in FIG. The present invention can be applied to a display portion 7402 having such a curved surface.

[0093] In a mobile phone 7400 shown in FIG. 3D, information can be displayed by touching the display portion 7402 with a finger or the like. You can also make a call or write an email using the This can be done by touching the display portion 7402 with a finger or the like.

[0094] The screen of the display unit 7402 has three main modes. The first is a display mode that mainly displays images. The first mode is a display mode, and the second mode is an input mode that mainly inputs information such as characters. This is a display + input mode that combines two modes: display mode and input mode.

[0095] For example, when making a call or creating an email, the display unit 7402 is used to input characters. This is the main character input mode, and you can input characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402. It's nice.

[0096] In addition, a detection device such as a gyro sensor or an acceleration sensor is provided inside the mobile phone 7400. By doing so, the orientation of the mobile phone 7400 (portrait or landscape) is determined, and the screen display of the display unit 7402 is can be set to switch automatically.

[0097] The screen mode can be switched by touching the display portion 7402 or by pressing a button on the housing 7401. The operation is performed by operating the button 7403. Also, depending on the type of image displayed on the display unit 7402, For example, if the image signal to be displayed on the display unit is video data, If it is data, it switches to display mode, and if it is text data, it switches to input mode.

[0098] In the input mode, the optical sensor of the display unit 7402 detects a signal and displays it. If there is no input by touch operation on the part 7402 for a certain period of time, the screen mode is changed to the input mode. Alternatively, the display mode may be switched from the normal mode to the display mode.

[0099] The display portion 7402 can also function as an image sensor. By touching the device with your palm or fingers and capturing an image of your palm print or fingerprint, you can authenticate your identity. In addition, a backlight that emits near-infrared light to the display unit or a sensing light source that emits near-infrared light By using this, it is possible to capture images of finger veins, palm veins, etc.

[0100] Furthermore, as another configuration of a mobile phone (including a smartphone), Fig. 3(D'-1) and Fig. It can also be applied to a mobile phone having a structure such as 3(D'-2).

[0101] In addition, when the structure is as shown in Figure 3(D'-1) or Figure 3(D'-2), character information and Image information and the like are stored on the first surfaces 7501(1) and 7501(2) of the housings 7500(1) and 7500(2). (2), but can also be displayed on the second screen 7502(1) and 7502(2). With this structure, you can keep the mobile phone in your breast pocket. Uses text information and image information displayed on the second page 7502(1), 7502(2), etc. The person can easily verify this.

[0102] As described above, electronic devices can be manufactured by using light-emitting devices including light-emitting elements according to embodiments of the present invention. It should be noted that the electronic devices to which the present invention can be applied are not limited to those described in this embodiment. It can be applied to electronic devices in all fields.

[0103] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiment modes. It is possible.

[0104] (Fourth embodiment) In this embodiment, a light-emitting device including a light-emitting element according to one embodiment of the present invention is used. An example will be described with reference to FIG.

[0105] FIG. 4 shows an example in which the light emitting device is used as an indoor lighting device 8001. It is also possible to make a large-area lighting device. By using a housing having a curved surface, it is possible to form a lighting device 8002 having a light-emitting area with a curved surface. The light-emitting element included in the light-emitting device shown in this embodiment mode is a thin film, and the design of the housing Therefore, lighting devices with a variety of elaborate designs can be formed. Furthermore, a large lighting device 8003 may be provided on the wall of the room.

[0106] In addition, by using a light emitting device on the surface of a table, it is possible to provide a lighting device that functions as a table. The light emitting device can be used as a light emitting device 8004. This allows the lighting device to function as furniture.

[0107] As described above, various lighting devices using the light-emitting device can be obtained. is included in one aspect of the present invention.

[0108] The structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. It is possible. [Example]

[0109] In this example, a light-emitting element 1 and a light-emitting element 2 for comparison are used as a light-emitting element according to one embodiment of the present invention. Light-emitting device 2 was fabricated and the characteristics were compared.

[0110] The element structures of the light-emitting element 1 and the comparative light-emitting element 2 are as follows: The light-emitting layer (II) has both a layer (1) and a layer (2) for obtaining phosphorescence. However, since the other parts are the same, the same structure as that of the light-emitting element 1 will be explained with reference to FIG. 5B, which explains the comparative light-emitting element 2, will be collectively explained using the same reference numerals. The light-emitting layer (II) 506b of the light-emitting element 1 has a laminated structure, and the second layer 50 The third layer 506(b3) formed between the first layer 506(b2) and the fourth layer 506(b4) The emission peaks of the light emitted from the second layer 506(b2) and the fourth layer 506(b4) are longer than those of the light emitted from the first layer 506(b1) and the fourth layer 506(b2). The structural formulas and abbreviations of the materials used in this example are as follows: Shown below.

[0111] [ka]

[0112] [ka]

[0113] <Fabrication of Light-Emitting Element 1 and Comparative Light-Emitting Element 2> The first electrode 501 is an electrode that functions as an anode, and is made of a glass substrate with a refractive index of 1.84. On the plate 500, indium tin oxide (ITO) was deposited by sputtering to a thickness of 110 nm. The electrode area was 2 mm × 2 mm.

[0114] Here, as a pretreatment, the surface of the substrate 500 is washed with water, and then subjected to UV ozone treatment for 370 seconds. After that, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about Pa. After vacuum baking at 190° C. for 60 minutes in the heating chamber of the vacuum deposition apparatus, the substrate 50 The mixture was allowed to cool for about 30 minutes.

[0115] An EL layer 503 and a second electrode 502 are formed in this order on the first electrode 501. As shown in FIG. 5(A), the EL layer 503 of the light-emitting element 1 includes a hole injection layer 504, a hole transport layer 505, and a hole transport layer 506. The electron transport layer 505, the light emitting layer 506 (light emitting layer (I) 506a, light emitting layer (II) 506b), The light-emitting layer (II) 506b includes a transport layer 507 and an electron injection layer 508. Multiple layers of different materials (506(b1), 506(b2), 506(b3), 506(b 5B, the comparative light-emitting element 2 has a laminated structure of The light-emitting layer 506 has a different structure from that of the light-emitting element 1 in the light-emitting layer (II) 506b'. In the embodiment, the common parts between the light-emitting element 1 and the comparative light-emitting element 2 will be described together. Only the different parts will be explained separately.

[0116] The hole injection layer 504 was formed by evaporating the solution in a vacuum deposition apparatus for 10 -4 After reducing the pressure to 100 Pa, 1,3,5-tri( Dibenzothiophen-4-yl)-benzene (abbreviation: DBT3P-II) and molybdenum oxide The ratio of DBT3P-II to molybdenum oxide was 1:0.5 (by mass). The first electrode 501 was formed by co-evaporation of a plurality of different materials. This is a vapor deposition method in which different evaporation sources are evaporated simultaneously. In both cases, the film thickness was set to 30 nm.

[0117] The hole transport layer 505 is formed by depositing PCPPn on the hole injection layer 504 to a thickness of 10 nm. did.

[0118] The light-emitting layer (I) 506a is formed by disposing 7-[4-(10-phenyl-9-anthracene)- tolyl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA ), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9 H-fluoren-9-yl)phenyl)-pyrene-1,6-diamine (abbreviation: 1,6mM emFLPAPrn), cgDBCzPA:1,6mMemFLPAPrn=1:0. The film was formed by co-evaporation so that the mass ratio was 0.25. The film thickness was 10 nm.

[0119] The light-emitting layer (II) 506b of the light-emitting element 1 shown in FIG. 5(A) has a laminated structure made up of multiple layers. Specifically, the first layer 506(b1), the second layer 506(b2), the third layer 506( The second layer 506 (b 2), the third layer 506(b3), and the fourth layer 506(b4) are all formed by the excitation of the exciplex. This is a structure that allows phosphorescence emission based on energy transfer.

[0120] The first layer 506(b1) is a layer of 2-[3'-(dibenzothiophene)-2-(2-methyl-2-phenylene sulfide]] on the light-emitting layer (I) 506a. [f,h]quinoxaline (abbreviated as 2mD BTBPDBq-II), N-(1,1'-biphenyl-4-yl)-N-[4-(9- (phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoro PCBBiF was added to 2mDBTBPDBq-II:PCBB The film was formed by co-evaporation so that the mass ratio of iF was 0.2:0.8. The film thickness was 2 nm. .

[0121] The second layer 506(b2) is formed by disposing 2mDBTBPDBq-II on the first layer 506(b1), PCBBiF, (acetylacetonato)bis(6-tert-butyl-4-phenylpyridine) Iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]) , 2mDBTBPDBq-II:PCBBiF:[Ir(tBuppm)2(acac) The film was formed by co-evaporation so that the mass ratio was 0.1:0.9:0.06. The value was m.

[0122] The third layer 506(b3) has 2mDBTBPDBq-II on the second layer 506(b2), PCBBiF, bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3 -(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,4- Pentanedionate-κ 2 O,O')iridium(III) (abbreviation: [Ir(dmdppr -dmp)2(acac)]), 2mDBTBPDBq-II:PCBBiF:[Ir (dmdppr-dmp)2(acac)] = 0.1:0.9:0.03 (mass ratio) The film was formed by co-evaporation so that the thickness was 5 nm.

[0123] The fourth layer 506(b4) has 2mDBTBPDBq-II on the third layer 506(b3), PCBBiF, [Ir(tBuppm)2(acac)], 2mDBTBPDBq-I I:PCBBiF:[Ir(tBuppm)2(acac)]=0.8:0.2:0.0 The film was formed by co-evaporation so that the mass ratio was 6. The film thickness was 20 nm.

[0124] The light-emitting layer (II) 506b' of the comparative light-emitting element 2 shown in FIG. 5(B) is a laminated layer made up of multiple layers. Specifically, the structure includes a first layer 506(b1), a second layer 506(b2'), a third layer The first layer 506(b1) has a laminated structure consisting of Since this is the same as the first layer 506(b1) in the light-emitting element 1, it can be fabricated in the same manner. The explanation will be omitted.

[0125] The second layer 506(b2') is formed by disposing 2mDBTBPDBq-II on the first layer 506(b1). , PCBBiF, [Ir(dmdppr-dmp)2(acac)], 2mDBTBP DBq-II:PCBBiF:[Ir(dmdppr-dmp)2(acac)]=0. The film was formed by co-evaporation in a mass ratio of 1:0.9:0.06. The film thickness was 5 nm. .

[0126] The third layer 506 (b3') is formed by disposing 2mDBTBPDBq-I on the second layer 506 (b2'). I, PCBBiF, [Ir(tBuppm)2(acac)], 2mDBTBPDBq -II:PCBBiF:[Ir(tBuppm)2(acac)]=0.8:0.2:0 The film was formed by co-evaporation so that the mass ratio was 0.06. The film thickness was 20 nm.

[0127] The electron transport layer 507 is formed by dissolving 2mDBTBPDB on the light-emitting layer (II) (506b, 506b'). After q-II was evaporated to a thickness of 15 nm, Bphen (abbreviation) was evaporated to a thickness of 15 nm. It was formed.

[0128] The electron injection layer 508 is formed by depositing lithium fluoride (LiF) on the electron transport layer 507 to a thickness of 1 nm. It was formed by vapor deposition.

[0129] The second electrode 502 functions as a cathode and is formed by depositing silver (Ag) on ​​the electron injection layer 508. and magnesium (Mg) were co-evaporated at a mass ratio of 1:0.5 to form a film with a thickness of 1 nm. After that, a silver film was formed to a thickness of 150 nm by sputtering. In the deposition process, the deposition was all carried out using a resistance heating method.

[0130] Although not shown in FIG. 5, the fabricated light-emitting element 1 and the comparative light-emitting element 2 were exposed to the air. The seal was placed in a glove box with a nitrogen atmosphere to prevent the seal from being broken. Apply 365 nm ultraviolet light at 6 J / cm 2 Irradiate and heat at 80°C for 1 hour. Processed.)

[0131] The element structures of the light-emitting element 1 and the comparative light-emitting element 2 obtained as described above are shown in Table 1. The light-emitting layer (I) 506a in the optical element 1 is marked with an * in the table. 1 and the light-emitting layer (II) The first layer 506(b1) included in 506b is marked with * in the table. 2 The second layer is denoted by 5 For 06(b2), please mark with an * in the table. 3 The third layer 506(b3) is indicated by of* 4 The fourth layer 506 (b4) is indicated by * in the table. 5Also, the comparative light For the first layer 506(b1) in element 2, the * in the table 2 and the second layer 506 For (b2'), please refer to the * in the table. 6 The third layer 506 (b3') is indicated by of* 5 Shown in.

[0132] [Table 1]

[0133] <Element characteristics of light-emitting element 1 and comparative light-emitting element 2> First, a hemispherical lens with a refractive index of 2.0 was used for the fabricated light-emitting element 1 and comparative light-emitting element 2. The substrate surface from which light is emitted was attached using a contact liquid with a refractive index of 1.78. Regarding the device characteristics, the total luminous flux was measured using an integrating sphere at room temperature (atmosphere maintained at 25°C). The results are shown in Table 2 below. The results shown in Table 2 are for 1000 cd / m 2 Nearby These are the main initial characteristic values ​​of the optical element 1 and the comparative light-emitting element 2.

[0134] [Table 2]

[0135] From the above results, it can be seen that the light-emitting element 1 fabricated in this example has a higher external quantum efficiency than the comparative light-emitting element 2. It was found that the efficiency of the LEDs was also improved. The specified range of the color temperature is 2600K to 7100K. The results showed that the temperature range was 600K to 3250K.

[0136] Furthermore, the light-emitting element 1 and the comparative light-emitting element 2 were 2 A current is passed with a current density of FIG. 6 shows the emission spectrum at the initial stage of driving when the light emitting element 1 and the comparative The emission spectrum of comparative light emitting element 2 is around 470 nm, around 547 nm, and around 613 nm. The fluorescent light emitted from the light-emitting layer (I) 506a has a peak near m, and the light It is suggested that this is due to phosphorescence from layer (II) (506b, 506b'). can be.

[0137] The difference in external quantum efficiency between the light-emitting element 1 and the comparative light-emitting element 2 was This is thought to be due to the laminated structure of the light-emitting layer (II) 506b in FIG. The light-emitting element 1 emits green and red light having emission peaks at around 547 nm and 613 nm. This can be explained by the fact that the intensity of the red light emitted from the comparative light-emitting element 2 is greater than that of the comparative light-emitting element 1. .

[0138] That is, in the light-emitting element 1, the light-emitting layer (II) 506b is a layer having a second layer 506(b2) and a The third layer 506(b3) formed between the fourth layer 506(b4) and the second layer 506 The emission peak has a wavelength longer than that of the emission peak obtained from the fourth layer 506 (b2) and the fourth layer 506 (b4). As a result, the excitation generated in the third layer 506(b3) It is believed that the luminous efficiency is improved because the diffusion of molecules into other layers can be suppressed.

[0139] Furthermore, in FIG. 6, the intensity of blue light emitted from the light-emitting element 1 has an emission peak at around 470 nm. The intensity of the light-emitting layer (II) is smaller than that of the comparative light-emitting element 2. For the above reasons, phosphorescence in the light-emitting layer (I This can be explained by the fact that the probability of energy transfer to 506a is low.

[0140] As a result, the ratio of the phosphorescent emission to the fluorescent emission of the light-emitting element 1 is This is thought to be because the proportion of the light-emitting element is higher than that of the comparative light-emitting element 2, resulting in a higher external quantum efficiency. .

[0141] The results of the reliability test on the light-emitting element 1 are shown in FIG. The horizontal axis shows the normalized brightness (%) when the brightness is 100%, and the horizontal axis shows the device operating time (h). The reliability test was conducted with an initial brightness of 5000 cd / m 2 and under the condition of constant current density The light-emitting element 1 was driven. As a result, it was found that the light-emitting element 1 was a light-emitting element with a long life. It was.

[0142] In addition, a light-emitting element having the same configuration as the light-emitting element 1 fabricated in this example was mounted on a substrate having a refractive index of 1.84. The light emitting surface of the substrate was formed to be 90mm x 90mm. By processing the glass, a lighting device with a light-emitting area of ​​90 mm x 90 mm was fabricated. The thickness of the ITO film on the electrode was 70 nm. The luminance of the fabricated lighting device was 1000 cd / m 2 The average color rendering index Ra is good at 84 in the vicinity, and the power efficiency is also good at 92 lm / W. This lighting device showed extremely high efficiency. In addition, the color temperature of this lighting device is 2800K, which is in line with the standard for incandescent light. The results show matching characteristics. [Example]

[0143] In this example, a light-emitting element 3 was fabricated as a light-emitting element according to one embodiment of the present invention, and its characteristics were evaluated. The light-emitting element 3 has the same structure as the light-emitting element 1 shown in Example 1, and is shown in FIG. As shown in (A), the light-emitting layer (I) 506a is a light-emitting layer from which fluorescent light is obtained. The layer (II) 506b is a light-emitting layer that emits phosphorescence. b has a laminated structure, and is between the second layer 506 (b2) and the fourth layer 506 (b4). The third layer 506(b3) formed on the second layer 506(b2) and the fourth layer 506(b 4) is formed to exhibit an emission peak at a wavelength longer than that of the emission peak obtained from The structural formulas and abbreviations of the materials used in this example are shown below.

[0144] [ka]

[0145] [ka]

[0146] <Fabrication of Light-Emitting Element 3> The first electrode 501 is an electrode that functions as an anode, and is a glass substrate with a refractive index of 1.84. Indium tin oxide (ITSO) containing silicon oxide was deposited on 500 by sputtering. The electrode was formed with a thickness of 70 nm and had an area of ​​81 cm. 2 In addition, the light emitted from the substrate The side that is served is frosted.

[0147] The light-emitting element 3 shown in this example has the following characteristics compared to the light-emitting element 1 and the comparative light-emitting element 2 shown in Example 1: The only difference is the electrode area, and the manufacturing method is the same. The composition of the light-emitting layer (I) 50 is shown in Table 3 below, and a detailed description thereof will be omitted. Among the light-emitting layer (I) 506a and the light-emitting layer (II) 506b, the light-emitting layer (I) 506a is capable of obtaining fluorescent light. The second layer 506(b2) and the third layer 506(b3) included in the light-emitting layer (II) 506b are The fourth layer 506(b3) and the fourth layer 506(b4) are both derived from exciplexes, similarly to the light-emitting element 1. This is a structure in which phosphorescence can be obtained based on energy transfer. For the light-emitting layer (I) 506a in the 1 and contained in the light-emitting layer (II) 506b. For the first layer 506(b1) included in the 2 and the second layer 506(b2) For details, please refer to the * in the table. 3 The third layer 506(b3) is indicated by * in the table. 4 Indicated by , and for the fourth layer 506 (b4), * in the table 5 Shown in.

[0148] [Table 3]

[0149] <Element characteristics of light-emitting element 3> The device characteristics of the fabricated light-emitting device 3 were measured at room temperature (in an atmosphere maintained at 25°C). The results are shown in Figure 8 and Table 4 below. The results shown in Table 4 are for 1000 cd / m 2 Nearby These are the main initial characteristic values ​​of the light-emitting element 3 in the experiment.

[0150] [Table 4]

[0151] From the above results, it can be seen that the light-emitting element 3 fabricated in this example has the same properties as the light-emitting element 1 shown in Example 1. It was found to have high external quantum efficiency. The correlated color temperature is also specified in the JIS standard. The lighting is within the specified range for indoor lighting (specifically, the correlated color temperature is 2600K to 7100K). The results showed that the material emitted spherical color light (2600K~3250K).

[0152] Furthermore, the light-emitting element 3 is supplied with 1.2 mA / cm 2 The light emission at the initial stage of operation when a current is passed through the device at a current density of The emission spectrum of the light-emitting element 3 is shown in FIG. 9. As shown in FIG. 9, the emission spectrum of the light-emitting element 3 is The emission layer (I) 506a has peaks at around 547 nm, 547 nm, and 613 nm. and phosphorescence from the light-emitting layer (II) 506b. This suggests that

[0153] Furthermore, the light-emitting element 3 shown in this example emits strong blue light having an emission peak around 470 nm. The intensity of red light emission, which has an emission peak around 613 nm, is very high compared to the intensity of red light. In the light-emitting layer (II) 506b of the light-emitting element 3, the second layer 506(b2) and the fourth layer The excitons generated in the third layer 506(b3) formed between the first and second layers 506(b4) The ratio of phosphorescence emission to fluorescence emission is reduced by suppressing diffusion to other layers. This is thought to be why the external quantum efficiency increased. [Example]

[0154] In this example, a light-emitting element 4 was fabricated as a light-emitting element according to one embodiment of the present invention, and its characteristics were evaluated. The light-emitting element 4 has a structure similar to that of the light-emitting element 1 shown in Example 1, and As shown in FIG. 5(A), the light-emitting layer (I) 506a is a light-emitting layer from which fluorescent light can be obtained. The light-emitting layer (II) 506b is a light-emitting layer that can emit phosphorescent light. 6b has a laminated structure, and is made up of a second layer 506(b2) and a fourth layer 506(b4). The third layer 506(b3) formed between the second layer 506(b2) and the fourth layer 506( b4) is formed to have an emission peak with a wavelength longer than that of the emission peak obtained from The structural formulas and abbreviations of the materials used in this example are shown below.

[0155] [ka]

[0156] [ka]

[0157] <Fabrication of Light-Emitting Element 4> The first electrode 501 is an electrode that functions as an anode, and is formed by depositing silicon oxide on a glass substrate 500. Indium tin oxide (ITSO) containing silicon was deposited to a thickness of 110 nm by sputtering. The electrode area was 2 mm × 2 mm.

[0158] The light-emitting element 4 shown in this example is fabricated in the same manner as the light-emitting element 1 shown in Example 1. Therefore, the element configuration that is characteristic of the light-emitting element 4 is shown in Table 5 below, and a detailed description will be given below. The light-emitting layer (I) 506a and the light-emitting layer (II) 506b of the light-emitting element 4 are omitted. The light-emitting layer (I) 506a is configured to emit fluorescent light, and the light-emitting layer (II) 506b The second layer 506(b2), the third layer 506(b3), and the fourth layer 506(b4) included in The structure shown in Table 5 provides phosphorescence based on energy transfer from the exciplex. The light-emitting layer (I) 506a of the light-emitting element 4 is marked with an asterisk (*) in the table. 1 and the light-emitting layer (II) The first layer 506(b1) included in 506b is marked with * in the table. 2 The second layer is denoted by 5 For 06(b2), please mark with an * in the table. 3 The third layer 506(b3) is indicated by of* 4 The fourth layer 506 (b4) is indicated by * in the table. 5 Shown in.

[0159] [Table 5]

[0160] <Element characteristics of light-emitting element 4> The device characteristics of the fabricated light-emitting device 4 were measured at room temperature (in an atmosphere maintained at 25°C). The results are shown in Figure 10 and Table 6 below. The results shown in Table 6 are for 1000 cd / m 2 Nearby 10 shows the main initial characteristic values ​​of the light-emitting element 4.

[0161] [Table 6]

[0162] From the above results, it is clear that the light-emitting device 4 fabricated in this example exhibits high external quantum efficiency. In addition, the correlated color temperature is within the range of indoor lighting specified in the JIS standard (specifically, Warm white light (2600K~3250K) with a correlated color temperature of 2600K~7100K The results showed that:

[0163] Furthermore, the light-emitting element 4 is supplied with 3.75 mA / cm 2 Light emission at the initial stage of operation when a current is applied at a current density of The spectrum is shown in FIG. 11. As shown in FIG. 11, the emission spectrum of the light-emitting element 4 is 46 The emission layer (I) has peaks at around 509 nm, 550 nm, and 611 nm. Fluorescence emission from 6a and phosphorescence emission from the light-emitting layer (II) 506b This suggests that

[0164] Furthermore, the light-emitting element 4 shown in this example emits strong blue light having an emission peak around 469 nm. The intensity of red light emission, which has an emission peak around 611 nm, is very high compared to the intensity of red light. In the light-emitting layer (II) 506b of the light-emitting element 4, the second layer 506(b2) and the fourth layer The excitons generated in the third layer 506(b3) formed between the first and second layers 506(b4) The ratio of phosphorescence emission to fluorescence emission is reduced by suppressing diffusion to other layers. This is thought to be why the external quantum efficiency increased.

[0165] Furthermore, a light-emitting element having the same configuration as the light-emitting element 4 fabricated in this example was fabricated on a substrate having a refractive index of 1.84. The light emitting surface of the substrate was formed to be 90mm x 90mm. By processing the glass, a lighting device with a light-emitting area of ​​90 mm x 90 mm was fabricated. The electrode was made of ITO, and its thickness was 70 nm. 00cd / m 2 The average color rendering index Ra is 83 in the vicinity, and the power efficiency is also good. The lighting device showed a high efficiency of 1lm / W. In addition, the color temperature of this lighting device is 3200K, which is warm white. It shows characteristics that meet color standards. [Explanation of symbols]

[0166] 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 Drive circuit section (source line drive circuit) 204a, 204b Drive circuit section (gate line drive circuit) 205 Sealing material 206 Sealing substrate 207 Wiring 208 FPC (Flexible Printed Circuit) 209 FET 210 FET 211 Switching FET 212 Current control FET 213 First electrode (anode) 214 Insulators 215 EL layer 216 Second electrode (cathode) 217 Light-emitting element 218 Space 500 boards 501 first electrode 502 Second electrode 503 EL layer 504 Hole injection layer 505 Hole transport layer 506 Light-emitting layer 506a luminescent layer (I), 506b luminescent 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 equipment 7101 Housing 7103 Display section 7105 Stand 7107 Display section 7109 Operation key 7110 Remote control device 7201 Main unit 7202 Case 7203 Display section 7204 keyboard 7205 External connection port 7206 Pointing Device 7302 Housing 7304 Display Panel 7305 Time Icon 7306 Other Icons 7311 Operation button 7312 Operation button 7313 Connection terminal 7321 Band 7322 Clasp 7400 mobile phone 7401 Housing 7402 Display section 7403 Operation buttons 7404 External connection part 7405 Speaker 7406 Microphone 7407 Camera 7500(1), 7500(2) enclosure 7501(1), 7501(2) 1st page 7502(1), 7502(2) 2nd page 8001 Lighting equipment 8002 Lighting equipment 8003 Lighting equipment 8004 Lighting equipment

Claims

1. a first layer, a second layer, a third layer, a fourth layer, and a fifth layer between the anode and the cathode; the first layer is located between the anode and the second layer and contains a fluorescent material; the second layer is located between the first layer and the third layer and does not contain a phosphorescent material; the third layer is located between the second layer and the fourth layer and includes a first phosphorescent material; the fourth layer is located between the third layer and the fifth layer and includes a second phosphorescent material; the fifth layer is located between the fourth layer and the cathode and includes a third phosphorescent material; an emission peak wavelength of the second phosphorescent material is longer than an emission peak wavelength of the first phosphorescent material; an emission peak wavelength of the second phosphorescent material is longer than an emission peak wavelength of the third phosphorescent material; The light-emitting element, wherein each of the third layer, the fourth layer, and the fifth layer has two organic compounds that combine to form an exciplex.

2. a first layer, a second layer, a third layer, a fourth layer, and a fifth layer between the anode and the cathode; the first layer is located between the anode and the second layer and contains a fluorescent material; the second layer is located between the first layer and the third layer and does not contain a phosphorescent material; the third layer is located between the second layer and the fourth layer and includes a first phosphorescent material; the fourth layer is located between the third layer and the fifth layer and includes a second phosphorescent material; the fifth layer is located between the fourth layer and the cathode and includes a third phosphorescent material; an emission peak wavelength of the second phosphorescent material is longer than an emission peak wavelength of the third phosphorescent material; the second phosphor is different from the first phosphor and the third phosphor; The light-emitting element, wherein each of the third layer, the fourth layer, and the fifth layer has two organic compounds that combine to form an exciplex.

3. A light-emitting element according to claim 1 or 2, and a transistor including an oxide semiconductor, The transistor is connected to the light-emitting element.

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