Light-emitting device

Abstract

It has a structure in which a fluorescent emitting layer and a phosphorescent emitting layer are stacked, and exhibits good luminescence efficiency. To provide the element. [Solution] An EL layer is provided between a pair of electrodes, the EL layer has a light-emitting layer, and the light-emitting layer has fluorescence A laminated structure consisting of a first light-emitting layer and a second light-emitting layer that exhibits phosphorescence is in contact with each other. The second light-emitting layer also includes at least multiple layers that form an excitation complex, and the excitation complex forms The resulting layer has a wavelength longer than the emission peaks obtained from each of the two layers. This is a light-emitting element having a stacked structure in which layers exhibiting emission peaks are in contact with each other.

Description

Technical Field

[0001] One aspect of the present invention relates to a light-emitting element in which an organic compound that emits light when an electric field is applied is sandwiched between a pair of electrodes, and also to a light-emitting device, an electronic device, and a lighting device having such a light-emitting element. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Or, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition (composition of matter). Therefore, more specifically, examples of the technical field of one aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, their driving methods, or their manufacturing methods.

[0002] Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Or, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition (composition of matter). Therefore, more specifically, examples of the technical field of one aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, their driving methods, or their manufacturing methods. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Or, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition (composition of matter). Therefore, more specifically, examples of the technical field of one aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, their driving methods, or their manufacturing methods. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Or, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition (composition of matter). Therefore, more specifically, examples of the technical field of one aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, their driving methods, or their manufacturing methods. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Or, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition (composition of matter). Therefore, more specifically, examples of the technical field of one aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, their driving methods, or their manufacturing methods. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Or, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition (composition of matter). Therefore, more specifically, examples of the technical field of one aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, their driving methods, or their manufacturing methods. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Or, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition (composition of matter). Therefore, more specifically, examples of the technical field of one aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, their driving methods, or their manufacturing methods.

Background Art

[0003] Light-emitting elements using an organic compound having characteristics such as thin and light weight, high-speed response, and driving at a low DC voltage as a light-emitting body are expected to be applied to next-generation flat panel displays. In particular, a display device in which light-emitting elements are arranged in a matrix is considered to have an advantage in that it has a wider viewing angle and better visibility compared to conventional liquid crystal display devices. Light-emitting elements using an organic compound having characteristics such as thin and light weight, high-speed response, and driving at a low DC voltage as a light-emitting body are expected to be applied to next-generation flat panel displays. In particular, a display device in which light-emitting elements are arranged in a matrix is considered to have an advantage in that it has a wider viewing angle and better visibility compared to conventional liquid crystal display devices. Light-emitting elements using an organic compound having characteristics such as thin and light weight, high-speed response, and driving at a low DC voltage as a light-emitting body are expected to be applied to next-generation flat panel displays. In particular, a display device in which light-emitting elements are arranged in a matrix is considered to have an advantage in that it has a wider viewing angle and better visibility compared to conventional liquid crystal display devices. Light-emitting elements using an organic compound having characteristics such as thin and light weight, high-speed response, and driving at a low DC voltage as a light-emitting body are expected to be applied to next-generation flat panel displays. In particular, a display device in which light-emitting elements are arranged in a matrix is considered to have an advantage in that it has a wider viewing angle and better visibility compared to conventional liquid crystal display devices.

[0004] The light-emitting mechanism of a light-emitting element is as follows: When a voltage is applied across a pair of electrodes sandwiching an EL layer containing a light-emitting body, carriers (electrons or holes) are injected from the electrodes, and these carriers recombine to form excitons. When the excitons return to the ground state, energy is released to emit light. The light-emitting mechanism of a light-emitting element is as follows: When a voltage is applied across a pair of electrodes sandwiching an EL layer containing a light-emitting body, carriers (electrons or holes) are injected from the electrodes, and these carriers recombine to form excitons. When the excitons return to the ground state, energy is released to emit light. The light-emitting mechanism of a light-emitting element is as follows: When a voltage is applied across a pair of electrodes sandwiching an EL layer containing a light-emitting body, carriers (electrons or holes) are injected from the electrodes, and these carriers recombine to form excitons. When the excitons return to the ground state, energy is released to emit light. ​​It is said that there are singlet excited states (S * ) and triplet excited state (T * ) knew Furthermore, the emission from the singlet excited state is called fluorescence, and the emission from the triplet excited state is called phosphorescence. And the statistical generation ratio in the light-emitting element is S * :T * It is assumed that the ratio is 1:3. It is being done.

[0005] Regarding such light-emitting elements, in order to improve their element characteristics, intersystem crossing (singlet excitation) is used. Development of light-emitting devices using phosphorescent materials that readily undergo transitions from a state to a triplet excited state. This is being actively pursued. Furthermore, different phosphorescent materials are used to obtain white light emission. A light-emitting device comprising layers containing the above is disclosed (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-522276 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In the case of the light-emitting element with the above configuration, all stacked light-emitting layers are light-emitting layers that exhibit phosphorescence (phosphorescence) It is composed of a light-emitting layer. This achieves high luminescence efficiency by utilizing phosphorescence. Not only can it be used, but it also has a light-emitting layer that exhibits fluorescence (fluorescent light-emitting layer) and a light-emitting layer that exhibits phosphorescence When a phosphorescent layer is stacked with the triplet excitons generated in the phosphorescent layer, the triplet excitons diffuse into the triplet layer. After the excitation energy is transferred to the fluorescent layer, deactivation occurs, resulting in a significant decrease in luminescence efficiency. This is because it has the problem of having to do so.

[0008] Therefore, in one aspect of the present invention, the structure is made in which a fluorescent emitting layer and a phosphorescent emitting layer are laminated. The present invention also provides a light-emitting element that exhibits good luminescence efficiency. Furthermore, in one aspect of the present invention, the above light-emitting element is The present invention provides a light-emitting device that can be applied and achieve low power consumption. Furthermore, one aspect of the present invention is the above To provide electronic devices and lighting devices that can achieve low power consumption by applying light-emitting elements. One aspect of the present invention relates to a novel light-emitting element, a novel light-emitting device, or a novel lighting device, etc. We will provide these. Note that the description of these issues does not preclude the existence of other issues. One aspect of the present invention does not necessarily have to solve all of these problems. Other issues will become clear from the descriptions in the specification, drawings, claims, etc. It is possible to extract other issues from descriptions such as specifications, drawings, and claims. [Means for solving the problem]

[0009] One aspect of the present invention has an EL layer between a pair of electrodes, the EL layer has a light-emitting layer, and the light-emitting layer is A laminated structure having a first light-emitting layer that exhibits fluorescence and a second light-emitting layer that exhibits phosphorescence is used. The second light-emitting layer includes at least a plurality of layers that form an excitation complex, and the excitation complex The layer formed has a wavelength longer than the emission peaks obtained from each of the two layers, between the two layers. This light-emitting element is characterized by having a stacked structure in which layers exhibiting a specific emission peak are in contact with each other.

[0010] Another aspect of the present invention includes an EL layer between a pair of electrodes, the EL layer having a light-emitting layer, The light-emitting layer consists of a first light-emitting layer that exhibits fluorescence and a second light-emitting layer that exhibits phosphorescence, in contact with each other. The material has at least a layered structure, and the second light-emitting layer comprises a material that forms an excitation complex and a phosphorescent material. It includes multiple layers, and the multiple layers are obtained from each of the two layers between two layers. It is characterized by having a layered structure in which layers exhibiting emission peaks with longer wavelengths than the emission peak are in contact. It is a light-emitting element.

[0011] Another aspect of the present invention includes an EL layer between a pair of electrodes, the EL layer having a light-emitting layer, The light-emitting layer consists of a first light-emitting layer that exhibits fluorescence and a second light-emitting layer that exhibits phosphorescence, in contact with each other. The material has at least a layered structure, and the second light-emitting layer comprises a material that forms an excitation complex and a phosphorescent material. It includes multiple layers, and the multiple layers are between two layers formed using the same material. The layers that exhibit emission peaks with longer wavelengths than the emission peaks obtained from each of the two layers are in contact with each other. This is a light-emitting element characterized by having a layered structure.

[0012] Another aspect of the present invention includes an EL layer between a pair of electrodes, the EL layer having a light-emitting layer, The light-emitting layer consists of a first light-emitting layer that exhibits fluorescence and a second light-emitting layer that exhibits phosphorescence, in contact with each other. The material has at least a layered structure, and the second light-emitting layer comprises a material that forms an excitation complex and a phosphorescent material. It includes multiple layers, each of which contains one or more common organic compounds. It contains seeds, and between the two layers, there are wavelengths longer than the emission peaks obtained from each of the two layers. This light-emitting element is characterized by having a stacked structure in which layers exhibiting an emission peak are in contact with each other.

[0013] Another aspect of the present invention includes an EL layer between a pair of electrodes, the EL layer having a light-emitting layer, The light-emitting layer consists of a first light-emitting layer that exhibits fluorescence and a second light-emitting layer that exhibits phosphorescence, in contact with each other. The device has at least a layered structure, the first light-emitting layer containing a fluorescent light-emitting material, and the second light-emitting layer containing phosphorus It contains multiple layers containing photoluminescent material, and the layers containing phosphorescent material are separated by two layers. It has a layered structure in which layers exhibiting emission peaks with longer wavelengths than the emission peaks obtained from each layer are in contact with each other. This is a light-emitting element characterized by the following:

[0014] Another aspect of the present invention includes an EL layer between a pair of electrodes, the EL layer having a light-emitting layer, The light-emitting layer consists of a first light-emitting layer that exhibits fluorescence and a second light-emitting layer that exhibits phosphorescence, in contact with each other. The layered structure is at least, and the first light-emitting layer comprises a fluorescent material and a T1 The second light-emitting layer contains a host material with a low energy level, and the second light-emitting layer contains a substance that forms an excitation complex and a phosphorescent substance. It includes multiple layers, and the multiple layers are obtained from each of the two layers between the two layers. It is characterized by having a layered structure in which layers exhibiting emission peaks with longer wavelengths than the emission peak are in contact with each other. It is a light-emitting element.

[0015] Another aspect of the present invention includes an EL layer between a pair of electrodes, the EL layer having a light-emitting layer, The light-emitting layer consists of a first light-emitting layer that exhibits fluorescence and a second light-emitting layer that exhibits phosphorescence, in contact with each other. The layered structure is at least, and the first light-emitting layer comprises a fluorescent material and a T1 The second light-emitting layer contains a host material with a low energy level, and the second light-emitting layer contains a substance that forms an excitation complex and a phosphorescent substance. It includes multiple layers, and the multiple layers are formed between two layers made of the same material. The intersection of two layers that exhibit emission peaks with longer wavelengths than the emission peaks obtained from each of the two layers. This is a light-emitting element characterized by having a layered structure.

[0016] Another aspect of the present invention includes an EL layer between a pair of electrodes, the EL layer having a light-emitting layer, The light-emitting layer consists of a first light-emitting layer that exhibits fluorescence and a second light-emitting layer that exhibits phosphorescence, in contact with each other. The layered structure is at least, and the first light-emitting layer comprises a fluorescent material and a T1 The second light-emitting layer contains a host material with a low energy level, and the second light-emitting layer contains a substance that forms an excitation complex and a phosphorescent substance. It includes multiple layers, and each of the multiple layers contains one or more common organic compounds. It contains, and between the two layers, emission with wavelengths longer than the emission peaks obtained from each of the two layers. This light-emitting element is characterized by having a stacked structure in which layers exhibiting optical peaks are in contact with each other.

[0017] Another aspect of the present invention includes an EL layer between a pair of electrodes, the EL layer having a light-emitting layer, The light-emitting layer consists of a first light-emitting layer that exhibits fluorescence and a second light-emitting layer that exhibits phosphorescence, in contact with each other. The layered structure is at least, and the first light-emitting layer comprises a fluorescent material and a T1 The second light-emitting layer contains a host material with a low energy level, and the second light-emitting layer contains multiple layers containing phosphorescent material, The layer containing the luminescent material has a higher emission peak between the two layers than the emission peaks obtained from each of the two layers. This light-emitting element is characterized by having a stacked structure in which layers exhibiting long-wavelength emission peaks are in contact with each other. .

[0018] Furthermore, one aspect of the present invention is a light-emitting device using a light-emitting element having the above-described configuration.

[0019] Furthermore, one aspect of the present invention is not limited to a light-emitting device having a light-emitting element, but also includes an electronic device having a light-emitting element. This also includes equipment and lighting devices. Therefore, the light-emitting devices and This refers to an image display device or a light source (including lighting devices). It also refers to a light-emitting device connected to... For example, FPC (Flexible Printed Circuit) or T Module with CP (Tape Carrier Package) attached, TC A module with a printed circuit board attached to the end of P, or a light-emitting element with COG (Chip Modules in which ICs (integrated circuits) are directly mounted using the On Glass method are luminescent. It may be included in the placement. [Effects of the Invention]

[0020] According to one aspect of the present invention, it is also acceptable to have a structure in which a fluorescent emitting layer and a phosphorescent emitting layer are laminated. It is possible to provide a light-emitting element that exhibits high luminescence efficiency. Furthermore, one aspect of the present invention relates to the above light emission By applying the element, it is possible to provide a light-emitting device that achieves low power consumption. Furthermore, the present invention One embodiment involves applying the above-mentioned light-emitting element to provide an electronic device and lighting device that achieve low power consumption. It can be provided. Alternatively, according to one aspect of the present invention, a novel light-emitting element, a novel light-emitting device Alternatively, we can provide novel lighting devices, etc. Note that the descriptions of these effects are as follows: This does not preclude the existence of other effects. Furthermore, one aspect of the present invention does not necessarily preclude the existence of these effects. It is not necessary to have all of these effects. Furthermore, any effects other than those mentioned above will be described in the specification, drawings, claims, etc. This will become clear from the description, and from the description in the specification, drawings, claims, etc. It is possible to extract effects other than those mentioned above. [Brief explanation of the drawing]

[0021] [Figure 1] A diagram illustrating the structure of a light-emitting element according to one aspect of the present invention. [Figure 2] A diagram illustrating a light-emitting device. [Figure 3] A diagram explaining electronic devices. [Figure 4] A diagram illustrating a lighting device. [Figure 5] A diagram illustrating the structure of light-emitting element 1 and comparative light-emitting element 2. [Figure 6] A figure showing the emission spectra of light-emitting element 1 and comparative light-emitting element 2. [Figure 7] A diagram showing the reliability of the light-emitting element 1. [Figure 8] A diagram showing the brightness-power efficiency characteristics of the light-emitting element 3. [Figure 9] A diagram showing the emission spectrum of the light-emitting element 3. [Figure 10] A diagram showing the brightness-current efficiency characteristics of the light-emitting element 4. [Figure 11] A diagram showing the emission spectrum of the light-emitting element 4. [Figure 12] A diagram illustrating the correlation of energy levels in the light-emitting layer. [Modes for carrying out the invention]

[0022] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is as follows Not limited to the description, the form and details thereof may be described without departing from the spirit and scope of the present invention. It is possible to modify it in various ways. Therefore, the present invention is described in the following embodiments. It is not meant to be interpreted in this way only.

[0023] (Embodiment 1) This embodiment describes a light-emitting element, which is one aspect of the present invention.

[0024] A light-emitting element according to one aspect 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 consists of a light-emitting layer (I) that produces fluorescence emission and a light-emitting layer (I) that produces phosphorescence emission. It has I). In this light-emitting element, charge generation occurs between the light-emitting layer (I) and the light-emitting layer (II). Even without layers (even without tandem elements), both fluorescence and phosphorescence can be achieved. It can be obtained efficiently. Below, the element structure of a light-emitting element, which is one embodiment of the present invention, is shown in Figure I will explain this in detail using 1.

[0025] The light-emitting element shown in Figure 1 has a light-emitting layer between a pair of electrodes (first electrode 101, second electrode 102). An EL layer 103 containing 106 is sandwiched in between, and the EL layer 103 is the first electrode (anode) 101 From the side: hole injection layer 104, hole transport layer 105, light-emitting layer 106, electron It has a structure in which a transport layer 107, an electron injection layer 108, etc. are sequentially stacked. Also, an emissive layer 106 It has a structure in which light-emitting layer (I) 106a and light-emitting layer (II) 106b are stacked. The stacking order of light-emitting layer (I) 106a and light-emitting layer (II) 106b is not particularly limited and is appropriate. It may be changed as appropriate.

[0026] The light-emitting layer (I) 106a contains a fluorescent light-emitting substance and a host material (organic compound), Efficiently convert triplet excitons generated from the material into triplet-triplet annihilation (TTA: triplet By performing et-triplet annihilation, singlet excitons It has a configuration that converts and causes a fluorescent material to emit light through energy transfer from singlet excitons. ru.

[0027] Specifically, the T1 level of the host material in the light-emitting layer (I) 106a (lowest triplet excitation energy) It is preferable that the energy level is lower than the T1 level of the fluorescent material. Typically, in the light-emitting layer The abundance ratio is overwhelmingly higher in the host material. The T1 level of the host material is a fluorescent substance. By using them in combination such that the T1 level is lower than that, the light-emitting layer (I) 106a The triplet excitons then enter the fluorescent material, which is present in only small amounts in the light-emitting layer (I) 106a. The probability of collisions between triplet excitons decreases due to them being trapped and localized in molecules. This prevents the occurrence of TTA and increases the probability of TTA occurring. This can increase the luminescence efficiency of the fluorescence emission in the light-emitting layer (I) 106a. As the fluorescent material, known substances can be used, and the emission color is blue (for example, (Having emission spectral peaks between 400nm and 480nm), green (e.g., 5 (Having emission spectrum peaks between 00nm and 560nm), red (e.g., 58 (Having emission spectral peaks between 0 nm and 680 nm), orange, yellow, etc., as appropriate. It may be used.

[0028] The light-emitting layer (II) 106b includes a structure in which at least three different layers are stacked, each As shown in Figure 1, the first layer 106(b1), the second layer 106(b2), and the third layer 10 Let's call it 6(b3). All three of these layers form an excited complex (exciplex). It contains two types of organic compounds and a phosphorescent substance that can form a phosphorescent material. The emission wavelength of the formed excited complex is the same as the emission wavelength of each organic compound forming the excited complex. Because they are located at longer wavelengths compared to (fluorescence wavelength), these fluorescence spectra are displayed at longer wavelengths. It can be converted to an emission spectrum located on the side, and the driving voltage can be further reduced. Furthermore, energy can be transferred from the excited complex to the phosphorescent material, resulting in high luminescence. Efficiency can also be achieved. In addition, in the light-emitting layer (II) 106b, The device may also have a layer made of an organic compound that does not contain phosphorescent material.

[0029] Furthermore, the three layers mentioned above show the emission peaks of phosphorescence obtained from the second layer 106(b2). The phosphorescence emission of the first layer 106(b1) and the third layer 106(b3) respectively It is formed to have a longer wavelength than the light.

[0030] Specifically, the second phosphorescent material used in the second layer 106(b2) is the same as the first layer 106( The first phosphorescent material used in b1), and the third phosphorescent material used in the third layer 106 (b3) A material with a longer wavelength emission peak than the material will be used. Note that emission layer (II)1 As the phosphorescent material used in these three layers of 06b, known materials are used. This can be done, and the emitted color is blue (for example, the emission spectrum between 400nm and 480nm). (Having a peak in the green spectrum, for example, between 500nm and 560nm) (having a peak), red (for example, the emission spectrum between 580nm and 680nm) Colors such as orange, yellow, etc. (with peaks), can be used as appropriate according to the above configuration. Let's assume that.

[0031] Furthermore, by using such a configuration for the light-emitting layer (II) 106b, the second layer 106( In b2), the emission peak is longest from the excited complex generated in the second layer 106(b2). It is possible to efficiently transfer energy to phosphorescent materials of a specific wavelength, and also to other layers. Because the diffusion of excitons can be suppressed, the luminescence efficiency of phosphorescence in the light-emitting layer (II) 106b can be increased. This can be enhanced. Furthermore, the light-emitting layer (II) 106b is formed only from the three layers mentioned above. It may be included, but there are two types of organic compounds that do not contain phosphorescent material and can form excitation complexes. It may further have layers containing compounds.

[0032] In the light-emitting layer (I) 106a and light-emitting layer (II) 106b, fluorescent material and phosphorescent material Other organic compounds used as host materials include mainly 10 -6 cm 2 / Vs or more Electron transport materials having an electron mobility of 10 -6 cm 2 Hole movement of / Vs or greater Examples include hole transport materials having a degree of luminescence. However, phosphorescent luminescence is observed in the luminescent layer (II) 106b. In the layers containing the substance, each layer contains combinations of the above organic compounds that can form excited complexes. We will use two or more species that are hybrids.

[0033] Furthermore, in the light-emitting layer (I) 106a and the light-emitting layer (II) 106b, the light-emitting material (fluorescent material) By dispersing phosphorescent substances (such as phosphorescent materials) in the above-mentioned organic compound, the light-emitting layer is made It can suppress crystallization. Also, it can suppress concentration quenching caused by a high concentration of luminescent material. This suppresses emission and increases the luminescence efficiency of the light-emitting element.

[0034] Furthermore, in the light-emitting layer (II) 106b, the T1 level of the above organic compound is the phosphorescent material. It is preferable that the T1 level is higher than that of the quality. The T1 level of electron transport materials and hole transport materials is If the T1 level is lower than that of the phosphorescent material, the triplet excitation energy of the phosphorescent material that contributes to emission Electron-transporting and hole-transporting materials quench the ghee, leading to a decrease in luminescence efficiency. This is to invite it.

[0035] By fabricating a light-emitting element that satisfies the above conditions, fluorescence emission and phosphorescence emission can be obtained. A light-emitting element can be obtained. Furthermore, fluorescence emission can be obtained using the materials described above. From the light-emitting layer (I) 106a and the light-emitting layer (II) 106b that produces phosphorescence Combinations of emission colors obtained (Emission color obtained in emission layer (I) 106a \ Emission layer (II The "luminescence color obtained with 106b" can be, for example, "blue, green, red, green". "Blue\Blue, Red, Green", "Blue\Yellow, Red, Green", "Blue\Green, Red, Yellow Colors: "Blue / Yellow / Red / Yellow", "Green / Green / Red / Green", "Green / Blue / Red ·Green", "Green\Yellow·Red·Green", "Green\Green·Red·Yellow", "Green\Yellow· Red and yellow, Red / green, Red / green, Red / blue, Red / green, Red / yellow Examples include "color red green", "red / green / red / yellow", and "red / yellow / red / yellow". It can be done. Note that the stacking relationship between light-emitting layer (I) 106a and light-emitting layer (II) 106b is reversed. The same combinations are possible in this case as well.

[0036] Normally, when a fluorescence-producing light-emitting layer and a phosphorescence-producing light-emitting layer are stacked, a phosphorescence-producing light-emitting layer is formed. The triplet excitation energy generated is transferred to the host material of the fluorescent layer, resulting in non-radiative deactivation. It is known that this can cause a decrease in luminescence efficiency. However, the luminescence shown in one aspect of the present invention The device generates triplet excitation energy from the excitation complex formed in the phosphorescent layer to the phosphorescent material. This configuration involves the movement of excitons to produce light, and the expansion of excitons from the excited complex to materials other than phosphorescent materials. Because scattering is inherently unlikely, not only fluorescence but also phosphorescence can be obtained efficiently. This is possible. However, in one aspect of the present invention, in the light-emitting layer (I) 106a, TTA is used. Since it has a configuration that can easily generate a singlet excited state, the light-emitting layer (II) 106 Even if there is a transfer of triplet excitation energy from the excited complex formed at b, It becomes possible to convert it into fluorescence emission.

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

[0038] As shown in FIG. 12, in the light-emitting layer (I) 106a, TTA occurs due to the collision of triplet excited molecules of the host material, and a part of the triplet excited molecules of the host material is converted into singlet excited molecules (a part is thermally deactivated). Then, the energy in the singlet excited state ( ) of the host material generated by this TTA S FH ) moves to the singlet excited state (S FG ) of the fluorescent light-emitting substance, and the energy is converted into fluorescence.

[0039] Furthermore, in the luminescent layer (II) 106b, the excited level (S) of the excited complex E , T E ) is the host material Excited levels (S) of (the first organic compound and the second organic compound) PH , T PH Smaller than ) Therefore, no excitation energy transfer occurs from the excited complex to the host material. No energy transfer occurs from this to other excited complexes. However, the excitation energy of the excited complex When it moves to a guest material (phosphorescent material), it can be converted into light emission. In the light-emitting layer (II) 106b, there is almost no diffusion of triplet excitation energy, and light emission occurs. It can be converted to [this].

[0040] Therefore, the energy at the interface where the light-emitting layer (I) 106a and the light-emitting layer (II) 106b are in contact. - Even if there is some movement (for example, the T of the phosphorescent material present at the interface) PG From T FH Ya T FG Energy transfer to (I) 106a and 106b Light emission can be obtained with good efficiency from both sides. In addition, in the light-emitting layer (I) 106a, Because singlet excited states are generated by the triplet excitation energy due to TTA, at the interface Even if energy transfer occurs, a portion of it is converted into fluorescence emission, therefore It is possible to suppress energy loss.

[0041] Next, we will explain a specific example of how to fabricate the above-mentioned light-emitting element.

[0042] The first electrode (anode) 101 and the second electrode (cathode) 102 are made of metal, alloy, or electrically conductive material. Indioxin compounds and mixtures thereof can be used. Specifically, indioxin oxide Mu - Contains indium tin oxide, silicon, or silicon oxide. Indium oxide-tin oxide, Indium oxide-zinc oxide Indium oxide containing tungsten oxide and zinc oxide, gold (Au), platinum (Pt), Nickel (Ni), Tungsten (W), Chromium (Cr), Molybdenum (Mo Iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), titanium (Ti) In addition, elements belonging to Group 1 or Group 2 of the periodic table, namely lithium (Li) and cesium Alkali metals such as um (Cs), and 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 these Alloys containing graphene and other materials can be used. Note that the first electrode (anode) 101 The second electrode (cathode) 102 is, for example, produced by sputtering or deposition (including vacuum deposition). It can be formed by (m), etc.

[0043] The hole injection layer 104 delivers holes to the light-emitting layer 106 via the highly hole-transporting hole transport layer 105. This is the injection layer, which contains a hole transport material and an acceptor material. By including a material and an acceptor substance, the acceptor substance allows electricity to be released from the hole transport material. When a child is pulled out, a hole is generated, which is then transmitted to the light-emitting layer 106 via the hole transport layer 105. Holes are injected. The hole transport layer 105 is formed using a hole transport material.

[0044] For example, the hole transport material used in the hole injection layer 104 and the hole transport layer 105 is 4 ,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) Or α-NPD) or N,N'-bis(3-methylphenyl)-N,N'-diphenyl- [1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''- Tris(carbazole-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'-bis Aromatic compounds such as fluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB) Aromatic amine compounds, 3-[N-(9-phenylcarbazole-3-yl)-N-phenyl [amino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-( 9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazo (Abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcal [Bazole-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-carbazeo Carbazole derivatives such as CzPA (abbreviated as CzPA) can be used. The substance is mainly 10 -6 cm 2 It is a material having a hole mobility of / Vs or greater. However, electrons Other materials may be used as long as they have high hole transport capabilities.

[0045] Furthermore, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphen 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 Using polymer compounds such as (phenyl)benzidine (abbreviation: Poly-TPD) It's also possible.

[0046] Furthermore, the acceptor material used in the hole injection layer 104 is the fourth element in the periodic table. Examples include oxides of metals belonging to groups 1 through 8. Specifically, molybdenum oxide. That is particularly preferable.

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

[0048] The fluorescent material used in the light-emitting layer (I) 106a emits the following singlet excitation energies. Examples include substances that convert light into light.

[0049] For example, N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N' -Diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-Cal Bazole-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (Abbreviation: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-di Phenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-di Phenyl-N-[4-(10-phenyl-9-antryl)phenyl]-9H-carbazo 3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-(te rt-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-antryl)- 4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: P) CBAPA), N,N''-(2-tert-butylanthracene-9,10-dibutyldi -4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine [Min] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl [2-Anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 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-carbazole-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-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), Kumari N545T, N,N'-diphenylquinacridone, (abbreviation: DPQd), rubrene, 5, 12-Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviated) 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] [Quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (Abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetrace n-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N ',N'-Tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluorantene -3,10-diamine (abbreviation: p-mPhAFD), {2-isopropyl-6-[2-( 1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ ij]Quinolysin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedin Trill (abbreviation: DCJTI), {2-tert-butyl-6-[2-(1,1,7,7- Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidine [-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 Trahydro-1H,5H-benzo[ij]quinoridine-9-yl)ethenyl]-4H-p Examples include ran-4-ylidene propanedinitrile (abbreviation: BisDCJ™). In particular, pyrenediamines such as 1,6-FLPAPrn and 1,6-mMemFLPAPrn. Condensed aromatic diamine compounds, such as those represented by the compound, have high hole-trapping properties and high luminescence efficiency. It is preferable because it is highly reliable.

[0050] Furthermore, the phosphorescent material used in the light-emitting layer (II) 106b is the following triplet excitation energy Examples include substances that convert ghee into light.

[0051] For example, bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinate- N,C 2’ Iridium(III) picolinate (abbreviation: Ir(CF3ppy)2(pi) c)) Bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’ ] Iri Dium(III) acetylacetonate (abbreviation: FIracac), Tris(2-phenyl Lupyridinate) Iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenyl Iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(a) cac)), Tris(acetylacetonate)(monophenanthroline)terbium(II) I) (Abbreviation: Tb(acac)3(Phen)), Bis(benzo[h]quinolinato)iri Dium(III) acetylacetonate (abbreviation: Ir(bzq)2(acac)), bis (2,4-diphenyl-1,3-oxazolato-N,C 2’ Iridium(III) acetate Chilacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4'-(par Fluorophenyl)phenyl]pyridinate-N,C 2’ Iridium(III) acetyl Acetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbe Nzothiazolat-N,C 2’ Iridium(III) acetylacetonate (abbreviation: Ir (bt)2(acac)), bis[2-(2'-benzo[4,5-α]thienyl)pyridyl Nato-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)), (acetylaceto Nato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(II) I) (Abbreviation: Ir(Fdpq)2(acac)), (acetylacetonato)bis(3,5) -Dimethyl-2-phenylpyradinate) Iridium(III) (Abbreviation: [Ir(mppr) -Me)2(acac)]), (acetylacetonato)bis(5-isopropyl-3-Me) Iridium(III) (Abbreviation: [Ir(mppr-iP r)2(acac)]), (acetylacetonato)bis(2,3,5-triphenylpyra Dinato) Iridium(III) (abbreviation: Ir(tppr)2(acac)), Bis(2, 3,5-Triphenylpyrazinate)(dipivaloylmethanato) Iridium(III) (abbreviated) Name: [Ir(tppr)2(dpm)]), (acetylacetonato)bis(6-tert -Butyl-4-phenylpyrimidinato) Iridium(III) (Abbreviation: [Ir(tBup pm)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidium) Sodium iridium(III) (abbreviation: [Ir(dppm)2(acac)]), 2,3, 7,8,12,13,17,18-Octaethyl-21H,23H-Porphyrin Platinum ( II) (Abbreviation: PtOEP), Tris(1,3-diphenyl-1,3-propanediona) (Monophenanthroline) europium(III) (Abbreviation: Eu(DBM)3(Phe n)), Tris[1-(2-tenoyl)-3,3,3-trifluoroacetonate](mono Phenanthroline europium(III) (abbreviation: Eu(TTA)3(Phen)) Some examples include:

[0052] In addition, instead of the phosphorescent material mentioned above, thermally activated delayed fluorescence (TADF) can be used. ) Materials can also be used. Note that delayed fluorescence in TADF materials is different from normal fluorescence. This refers to luminescence that has a similar spectrum but a significantly longer lifetime. Its lifetime is 10 -6 seconds Preferably 10 -3 It is more than a second.

[0053] Specific TADF materials include, for example, fullerenes and their derivatives, and proflavins. Examples include cridine derivatives and eosin. Also, magnesium (Mg) and zinc (Zn) Cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or P Examples include metal-containing porphyrins containing radium (Pd), etc. For example, protoporphyrin-tin fluoride complex (SnF2(Proto IX) )), Mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), Hematopor Firin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrinte Tramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), Ethoethylporphyrin-tin fluoride complex (SnF2(OEP)), Ethioporphyrin -Tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride Examples include the complex (PtCl2OEP). Furthermore, 2-(biphenyl-4-yl)-4 ,6-bis(12-phenylindoro[2,3-a]carbazol-11-yl)-1, 3,5-triazine (PIC-TRZ) and other π-electron-rich heteroaromatic rings and π-electron-deficient heteroaromatic rings Heterocyclic compounds having an aromatic ring can also be used. Furthermore, π-electron-rich heterocyclic aromatic rings and Substances in which a π-electron-deficient heteroaromatic ring is directly bonded to a π-electron-rich heteroaromatic ring have the properties of a donor and a donor of a π-electron-rich heteroaromatic ring. The acceptor properties of the π-electron-deficient heteroatom ring become stronger, and the energy difference between S1 and T1 becomes It is particularly desirable because it becomes smaller.

[0054] The organic compound used in the light-emitting layer (I) 106a is 9-phenyl-3-[4-(10- Phenyl-9-antryl)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 Bazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-antryl)phenyl ]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-( 9,10-Diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d ]Fran (abbreviation: 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9 H-Fluorene-9-yl)-biphenyl-4'-yl}anthracene (abbreviation: FLPP) Examples of anthracene compounds include those listed in A). Note that substances having an anthracene skeleton are phosphate When used as a material, it is possible to realize a light-emitting layer with good luminescence efficiency and durability. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA exhibit very good characteristics. It is preferable because it indicates sexuality.

[0055] As an electron transport material, which is an organic compound used in the light-emitting layer (II) 106b, nitrogen-containing complex 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-carbazole-9-yl)phenyl]dibenzo [f,h]Quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothio Fen-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) and other quinoxalines Examples include dibenzoquinoxaline derivatives.

[0056] Furthermore, as a hole transport material, which is an organic compound used in the light-emitting layer (II) 106b, π-electric heteroaromatic compounds with excess of ions (e.g., carbazole derivatives and indole derivatives) and aromatic compounds Min compounds are preferred, for example, 4-phenyl-4'-(9-phenyl-9H-carbazo (Il-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-di(1-na Phthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine N (abbreviation: PCBNBB), 3-[N-(1-naphthyl)-N-(9-phenylcarbazo [Il-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), 4, 4',4''-Tris[N-(1-naphthyl)-N-phenylamino]triphenylamino (Abbreviation: 1'-TNATA), 2,7-bis[N-(4-diphenylaminophenyl) -N-phenylamino]-spiro-9,9'-bifluorene (abbreviation: DPA2SF), N ,N'-bis(9-phenylcarbazole-3-yl)-N,N'-diphenylbenzene -1,3-diamine (abbreviation: PCA2B), N-(9,9-dimethyl-2-diphenyl Mino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), N,N', N''-triphenyl-N,N',N''-tris(9-phenylcarbazole-3-I) (L)Benzene-1,3,5-triamine (abbreviation: PCA3B), 2-[N-(9-phenyl Lucarbazole-3-yl)-N-phenylamino]spiro-9,9'-bifluoren( Abbreviation: PCASF), 2-[N-(4-diphenylaminophenyl)-N-phenylami [N]spiro-9,9'-bifluorene (abbreviation: DPASF), N,N'-bis[4-(ca [Luvazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluore n-2,7-diamine (abbreviation: YGA2F), 4,4'-bis[N-(3-methylphenicol) [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-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarb Zol (abbreviation: PCzPCA1), 3-[N-(4-diphenylaminophenyl)-N- Phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis [N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarb Zol (abbreviation: PCzDPA2), 4,4'-bis(N-{4-[N'-(3-methylf [phenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation) :DNTPD), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-na Phthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 3,6-bis [N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenyl One example is carbazole (abbreviated as PCzPCA2).

[0057] The electron transport layer 107 is a layer containing a material with high electron transport properties. The electron transport layer 107 contains A lq3, Tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq3), Bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq2), B Alq, Zn(BOX)2, bis[2-(2-hydroxyphenyl)benzothiazolat] Metal complexes such as zinc (abbreviated as Zn(BTZ)2) can be used. Also, 2-(4 (-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazo PBD (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3 ,4-Oxadiazole-2-yl]benzene (abbreviation: OXD-7), 3-(4-ter t-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-tria Zole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl) (Phenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTA) Z), vasophenanthroline (abbreviation: Bphen), vasocuproin (abbreviation: BCP) , 4,4'-bis(5-methylbenzoxazole-2-yl)stilbene (abbreviation: Bz Hetero-aromatic compounds such as Os can also be used. In addition, poly(2,5-pyridinedi (Abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)- co-(pyridine-3,5-diyl) (abbreviation: PF-Py), poly[(9,9-dioc) (Chillfluoren-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl) Polymer compounds such as ) (abbreviation: PF-BPy) can also be used. Matter is mainly 1 × 10 -6 cm 2 It is a substance with an electron mobility of / Vs or greater. Any material other than those mentioned above can be used as the electron transport layer 107 if it has higher electron transport capabilities than pores. It's okay to be there.

[0058] Furthermore, the electron transport layer 107 is not only a single layer, but also consists of two or more layers made of the above material stacked together. It may be considered as such.

[0059] The electron injection layer 108 is a layer containing a material with high electron injection potential. Lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), Lithium oxide (LiO x Alkali metals, alkaline earth metals, or similar materials such as ) Compounds such as erbium fluoride (ErF3) can be used. Compounds of this group can be used. Alternatively, an electride can be used in the electron injection layer 108. i. The electride is, for example, a mixed oxide of calcium and aluminum with electrons Examples include substances to which high concentrations of the substance are added. Furthermore, the substance constituting the electron transport layer 107 described above... You can also use this.

[0060] Furthermore, the electron injection layer 108 is a composite material made by mixing an organic compound and an electron donor. Materials may be used. In such composite materials, electrons are generated in the organic compound by the electron donor. Therefore, it exhibits excellent electron injection and electron transport properties. In this case, as an organic compound, It is preferable that the material is excellent in transporting the generated electrons, and specifically, for example, the material described above The material constituting the subtransport layer 107 (such as a metal complex or a heteroaromatic compound) can be used. The electron donor can be any substance that exhibits electron-donating properties towards organic compounds. Specifically Alkali metals, alkaline earth metals, and rare earth metals are preferred, as are lithium, cesium, and ma Examples include magnesium, calcium, erbium, and ytterbium. Also, alkalis. Metal oxides and alkaline earth metal oxides are preferred, as are lithium oxides, calcium oxides, Examples include barium oxides. Additionally, using a Lewis base such as magnesium oxide can be... It is also possible to use organic compounds such as tetrathiafulvalene (abbreviated as TTF). It's also possible.

[0061] Furthermore, the hole injection layer 104, hole transport layer 105, and 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 methods such as vapor deposition (including vacuum deposition), inkjet, and coating. ru.

[0062] The above-described light-emitting element reacts to the potential difference generated between the first electrode 101 and the second electrode 102. As more carriers are injected, holes and electrons recombine in the EL layer 103, generating It emits light. And this light is emitted from either the first electrode 101 or the second electrode 102. Or it is taken out to the outside through both. Thus, the first electrode 101 and the second electrode 1 Either one or both of 02 will be a light-transmitting electrode.

[0063] By forming a light-emitting element having the structure described in this embodiment, fluorescence emission and In a light-emitting element that produces phosphorescence, the luminescence efficiency of the phosphorescence is particularly increased, and the entire light-emitting element and This allows for the creation of light-emitting elements with high luminescence efficiency.

[0064] The configuration shown in this embodiment may be used in appropriate combination with the configurations shown in other embodiments. It shall be possible.

[0065] (Embodiment 2) In this embodiment, as an example of a light-emitting device having an light-emitting element according to one aspect of the present invention, A dual-matrix type light-emitting device will be explained using Figure 2. The light-emitting device can be fitted with the light-emitting element described in Embodiment 1.

[0066] Figure 2(A) is a top view showing the light-emitting device, and Figure 2(B) is a dashed line AA of Figure 2(A). This is a cross-sectional view taken by cutting along the line '. The active matrix type light-emitting device according to this embodiment is A pixel section 202 and a drive circuit section (source line drive circuit) 203 are provided on the element substrate 201. It has a drive circuit section (gate line drive circuit) 204a and 204b, and a pixel section 202 The drive circuit section 203 and the drive circuit sections 204a and 204b are sealed by the sealing material 205. It is sealed between the element substrate 201 and the sealing substrate 206.

[0067] Furthermore, the element substrate 201 includes a drive circuit section 203 and drive circuit sections 204a and 204b. to an external signal (e.g., video signal, clock signal, start signal, or reset signal) A wiring harness 207 is provided for connecting external input terminals that transmit electrical potentials (such as numbers). Here, an FPC (Flexible Printed Circuit) 208 is provided as an external input terminal. An example is shown. Note that only FPC is shown in the diagram, but this FPC also has a pad. A lint-covered wiring board (PWB) may be attached. The light-emitting device in this specification includes 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 considered as such.

[0068] Next, the cross-sectional structure will be explained using Figure 2(B). The drive circuit section is located on the element substrate 201. And a pixel section is formed, but here, the drive circuit section 203, which is a source line drive circuit, The pixel section 202 is shown.

[0069] The drive circuit section 203 is illustrated by a configuration combining FET 209 and FET 210. It is present. Furthermore, the FETs 209 and 210 in the drive circuit section 203 are unipolar (N-type). The circuit may be formed by including either a P-type or N-type transistor (or only one of the two types). It may also be formed by a CMOS circuit including a transistor and a P-type transistor. In terms of implementation, a driver-integrated type with a drive circuit formed on a circuit board is shown, but this is not necessarily required. In fact, the drive circuit can be formed externally rather than on the circuit board.

[0070] Furthermore, the pixel section 202 includes a switching FET 211 and a current control FET 212. The first electric component is electrically connected to the wiring (source electrode or drain electrode) of the FET212. It is formed by multiple pixels including a pole (anode) 213. In this embodiment, The pixels are controlled by two FETs: a switching FET 211 and a current control FET 212. An example of what constitutes part 202 has been shown, but it is not limited to this. For example, three or more FE A pixel unit 202 may be formed by combining T and a capacitive element.

[0071] FETs 209, 210, 211, and 212 are examples of staggered and inverse staggered transistors. An inverter can be applied. It should be used with FETs 209, 210, 211, and 212. Examples of semiconductor materials that can do this include Group IV (silicon, etc.) semiconductors and 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; for example, amorphous semiconductors or crystalline semiconductors. Crystalline semiconductors can be used, particularly as FETs 209, 210, 211, and 212. It is preferable to use an oxide semiconductor. Examples of such oxide semiconductors include In-Ga acid In-M-Zn oxide (where M is Al, Ga, Y, Zr, La, Ce, or Nd) Examples include FET209, 210, 211, and 212, for example, energy g Oxides with a cap of 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. By using semiconductor materials, the off-current of the transistor can be reduced.

[0072] Furthermore, an insulator 214 is formed covering the end of the first electrode 213. Here, insulation Material 214 is formed by using a positive-type photosensitive acrylic resin. In this configuration, the first electrode 213 is used as the anode.

[0073] Furthermore, a curved surface with curvature is formed at the upper or lower end of the insulator 214. Preferably, by forming the shape of the insulator 214 as described above, the upper layer of the insulator 214 The coating properties of the formed film can be improved. For example, the material of the insulator 214 and Therefore, either a negative-type photosensitive resin or a positive-type photosensitive resin can be used. This applies not only to organic compounds but also to inorganic compounds, such as silicon oxide, silicon oxide nitride, and silicon nitride. Cones, etc., can be used.

[0074] On the first electrode (anode) 213, the EL layer 215 and the second electrode (cathode) 216 are stacked. It is done. The EL layer 215 is provided with at least an emissive layer, and the emissive layer is implemented It has the layered structure described in Embodiment 1. In addition, the EL layer 215 has a hole injection layer in addition to the light-emitting layer. A hole transport layer, electron transport layer, electron injection layer, charge generation layer, etc., can be provided as appropriate.

[0075] Furthermore, the first electrode (anode) 213, the EL layer 215, and the second electrode (cathode) 216 are stacked together. In the structure, a light-emitting element 217 is formed. First electrode (anode) 213, EL layer 215 and As for the material used for the second electrode (cathode) 216, the material shown in Embodiment 1 is used. This is possible. Also, although not shown in the diagram here, the second electrode (cathode) 216 is connected to the external input terminal. It is electrically connected to a certain FPC208.

[0076] Furthermore, although only one light-emitting element 217 is shown in the cross-sectional view in Figure 2(B), the pixel section 2 In 02, a plurality of light-emitting elements, including a light-emitting element according to one aspect of the present invention, are arranged in a matrix. It is assumed that it is positioned as follows. Furthermore, the pixel section 202 is capable of emitting three types of light (R, G, B). To selectively form light-emitting elements and create a light-emitting device capable of full-color display. This is possible. In addition to light-emitting elements that can produce three types of light (R, G, B), for example, white Light-emitting elements that produce light in colors such as white (W), yellow (Y), magenta (M), and cyan (C). Child elements may be formed. For example, the above-mentioned light-emitting element can be used to obtain three types of light (R, G, B). By adding light-emitting elements that can produce several types of light, color purity can be improved and power consumption reduced. These effects can be obtained. In addition, to narrow the range of each emission color, the resonance of light between electrodes A configuration with a micro-optical resonator (microcavity) structure that utilizes this effect is also possible. Furthermore, by combining it with a color filter, it can function as a light-emitting device capable of full-color display. Furthermore, combining a tandem structure with the configuration of a light-emitting element, which is one aspect of the present invention, is also possible. Optical elements may also be used.

[0077] Furthermore, by bonding the sealing substrate 206 to the element substrate 201 with the sealing material 205, A light-emitting element is placed in the space 218 surrounded by the element substrate 201, the sealing substrate 206, and the sealing material 205. The structure is equipped with child 217. Furthermore, the space 218 contains an inert gas (nitrogen or nitrate). This includes configurations in which a sealant (such as Lugon) is used as the filling material, as well as configurations in which a sealant 205 is used as the filling material.

[0078] Furthermore, it is preferable to use epoxy resin or glass frit for the sealing material 205. These materials should ideally be as impermeable to moisture and oxygen as possible. In addition to glass substrates and quartz substrates, FRP (Fiber-R) is also used as a material for the encapsulation substrate 206. reinforced plastics, PVF (polyvinyl fluoride), polyester A plastic substrate made of tel or acrylic can be used as a sealing material. When using glass frit, the element substrate 201 and the encapsulation substrate 206 are selected from the viewpoint of adhesion. It is preferable that the substrate is a glass substrate.

[0079] As described above, an active matrix type light-emitting device can be obtained. In terms of application methods, an active matrix type light-emitting device will be described as an example of a light-emitting device. However, a passive matrix to which a light-emitting element, which is one aspect of the present invention described in Embodiment 1, is applied It is also possible to create a Rix-type light-emitting device.

[0080] In the case of an active matrix light-emitting device, the structure of the transistor (FET) is not particularly limited. For example, staggered or inverse staggered FETs can be appropriately used. Also, the driving circuit formed on the FET substrate may be composed of N-type and P-type FETs, or may be composed of only one of N-type FETs or P-type FETs. Furthermore, the crystallinity of the semiconductor film used for the FET is not particularly limited. For example, an amorphous semiconductor film or a crystalline semiconductor film can be used. As the semiconductor material, in addition to group IV (such as silicon) semiconductors, group III (such as gallium) semiconductors, compound semiconductors (including oxide semiconductors), organic semiconductors, etc. can be used. Note that the configuration shown in this embodiment can be used by appropriately combining the configurations shown in other embodiments.

[0081]

[0082] (Embodiment 3) In this embodiment, an example of various electronic devices completed using a light-emitting device manufactured by applying a light-emitting element, which is an aspect of the present invention, will be described with reference to FIG. 3.

[0083] Examples of electronic devices to which the light-emitting device is applied include, for example, television devices (also referred to as TVs or television receivers), monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones (also referred to as mobile phones or mobile phone devices), portable game machines, portable information terminals, audio playback devices, and large game machines such as pachinko machines. Specific examples of these electronic devices are shown in FIG. 3.

[0084] FIG. 3(A) shows an example of a television device. The television device 7100 has a housing The display unit 7103 is incorporated into the body 7101. The display unit 7103 displays images. It is possible to do so, and the light-emitting device can be used in the display unit 7103. This shows a configuration in which the housing 7101 is supported by the stand 7105.

[0085] The television unit 7100 is operated using the control switches on the housing 7101 and a separate remote control. This can be done using the control unit 7110. The remote control unit 7110 has control keys 7109 allows you to control the channel and volume, and the information is displayed on the display unit 7103. The video can be controlled. Furthermore, the remote control unit 7110 can be controlled by the remote control unit. A display unit 7107 may be provided to display the information output from 7110.

[0086] The television system 7100 will consist of a receiver, modem, and other components. It can receive more general television broadcasts, and furthermore, via a modem, it can receive them via wired or wireless connection. By connecting to a communication network, one-way (sender to receiver) or two-way (sender to receiver) communication is possible. It is also possible to communicate information between believers and recipients, or between recipients themselves.

[0087] Figure 3(B) shows a computer, consisting of the main unit 7201, the casing 7202, the display unit 7203, and keys. Includes board 7204, external connection port 7205, pointing device 7206, etc. Furthermore, the computer is manufactured by using a light-emitting device in its display unit 7203. It is possible.

[0088] Figure 3(C) shows a smartwatch, consisting of a housing 7302, a display panel 7304, and operation buttons. It has connectors 7311, 7312, connection terminal 7313, band 7321, fastener 7322, etc. and so on.

[0089] The display panel 7304 mounted on the housing 7302 that also serves as a bezel part has a non-rectangular display area. The display panel 7304 can display an icon 7305 representing time, other icons 7306, etc. and so on.

[0090] Incidentally, the smartwatch shown in Fig. 3(C) can have various functions. For example, it can have a function of displaying various information (such as still images, moving images, text images, etc.) on the display part, a touch panel function, a function of displaying a calendar, date or time, etc., a function of controlling processing by various software (programs), a wireless communication function, a function of connecting to various computer networks using the wireless communication function, a function of transmitting or receiving various data using the wireless communication function, a function of reading a program or data recorded on a recording medium and displaying it on the display part, etc. and so on. Moreover, inside the housing 7302, there can be a speaker, a sensor (including functions of measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, inclination, vibration, odor or infrared rays), a microphone, etc. Incidentally, the smartwatch can be manufactured by using a light-emitting device for its display panel 7304. and so on. and so on. and so on.

[0091] Also, inside the housing 7302, there can be a speaker, a sensor (including those for measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, inclination, vibration, odor or infrared rays), a microphone, etc. and so on. and so on. Incidentally, the smartwatch can be manufactured by using a light-emitting device for its display panel 7304. and so on.

[0092] Fig. 3(D) shows an example of a mobile phone (including a smartphone). The mobile phone 7 The 400 consists of a casing 7401, a display unit 7402, a microphone 7406, a speaker 7405, and a camera It is equipped with a 7407 connector, an external connection unit 7404, and an operation button 7403. When a light-emitting element according to one embodiment of the light is formed on a flexible substrate, as shown in Figure 3(D) It can be applied to the display unit 7402 which has a curved surface.

[0093] The mobile phone 7400 shown in Figure 3(D) allows information to be accessed by touching the display unit 7402 with a finger or the like. You can input [text]. Also, you can perform operations such as making a phone call or composing an email. This can be done by touching the display unit 7402 with a finger or the like.

[0094] The display unit 7402 has three main modes. The first is a display that primarily displays images. The first mode is display mode, the second is input mode which is mainly for inputting information such as characters. The third is display mode. This is a display + input mode, which is a combination of two modes: display mode and input mode.

[0095] For example, when making a phone call or composing an email, the display unit 7402 is used for text input. In this case, the primary text input mode should be used, and you should perform the input operation for the characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display unit 7402. It's nice.

[0096] Furthermore, detection devices such as a gyro sensor and an accelerometer are installed inside the mobile phone 7400. This determines the orientation (vertical or horizontal) of the mobile phone 7400 and the screen display of the display unit 7402. It can be configured to switch automatically.

[0097] Furthermore, the screen mode can be switched by touching the display unit 7402 or by pressing the button on the housing 7401. This is performed by operating unit 7403. Furthermore, the type of image displayed on display unit 7402 also affects the operation. It can also be configured to switch between them. For example, if the image signal displayed on the display unit is video data If it's a "T" character, switch to display mode; if it's text data, switch to input mode.

[0098] Furthermore, in input mode, the signal detected by the optical sensor of the display unit 7402 is detected and displayed If there is no input via touch operation on unit 7402 for a certain period of time, the screen mode will be changed to input mode. You may also control the system to switch from that display mode to a different mode.

[0099] The display unit 7402 can also function as an image sensor. For example, the display unit 74 By touching device 02 with the palm or fingers, the user can be authenticated by capturing images of their palm print, fingerprints, etc. Furthermore, the display unit may have a backlight that emits near-infrared light or a sensing light source that emits near-infrared light. Using this method, it is also possible to image finger veins, palmar veins, and other veins.

[0100] Furthermore, another configuration of a mobile phone (including smartphones) is shown in Figure 3(D'-1) and Figure It can also be applied to mobile phones having a structure like 3(D'-2).

[0101] Furthermore, in cases where the structure is as shown in Figure 3(D'-1) or Figure 3(D'-2), the text information and Image information etc. on the first surface 7501(1), 7501 of the enclosure 7500(1), 7500(2) (2) In addition, it can be displayed on the second side 7502(1) and 7502(2). With this structure, you can keep your mobile phone in your breast pocket, Use the text information and image information displayed on pages 7502(1), 7502(2), etc. The person can easily verify this.

[0102] As described above, an electronic device is made by applying a light-emitting device including a light-emitting element, which is one aspect of the present invention. It can be obtained. Note that the applicable electronic devices are not limited to those shown in this embodiment. It can be applied to electronic devices in all fields.

[0103] The configuration shown in this embodiment may be used in appropriate combination with the configurations shown in other embodiments. It is possible.

[0104] (Embodiment 4) In this embodiment, a lighting device to which a light-emitting device including a light-emitting element, which is one aspect of the present invention, is applied. Let's illustrate one example using Figure 4.

[0105] Figure 4 shows an example in which the light-emitting device is used as an indoor lighting device 8001. Note that the light-emitting device is large Because it can be scaled up over an area, it is also possible to create large-area lighting devices. In addition, it can be used on curved surfaces. By using such a housing, it is also possible to form a lighting device 8002 in which the light-emitting area has a curved surface. The light-emitting element included in the light-emitting device shown in this embodiment is a thin film, and the housing design It offers a high degree of freedom. Therefore, it is possible to create lighting devices with a wide variety of designs. Furthermore, a large lighting fixture 8003 may be installed on the interior wall.

[0106] Furthermore, by using the light-emitting device on the surface of the table, it also functions as a table. This can be made into device 8004. Furthermore, a light-emitting device can be used in some of the other furniture. This allows for the creation of lighting fixtures that also function as furniture.

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

[0108] Furthermore, the configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments. It is possible. [Examples]

[0109] In this embodiment, an element-emitting element 1 is used as an element-emitting element according to one aspect of the present invention, and a comparison is used for comparison. We fabricated a second light-emitting element and compared its characteristics.

[0110] The element structure of light-emitting element 1 and comparative light-emitting element 2 is such that fluorescence emission is obtained from the light-emitting layer (I It has both a light-emitting layer (II) that produces phosphorescence and a light-emitting layer (II), but the composition of the light-emitting layer (II) These are all different. However, everything else is the same, so Figure 5(A) explains the light-emitting element 1. Figure 5(B), which illustrates the comparison light-emitting element 2, will be explained together using common reference numerals. Furthermore, the light-emitting layer (II) 506b of the light-emitting element 1 has a stacked structure, and the second layer 50 The third layer 506(b3) formed between 6(b2) and the fourth layer 506(b4) is The emission peaks obtained from layer 2 506(b2) and layer 4 506(b4) are longer It has a configuration that exhibits emission peaks at specific wavelengths. Furthermore, the structural formula and abbreviation of the material used in this embodiment are provided below. See 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 glass with a refractive index of 1.84. A 110 nm film of indium tin oxide (ITO) is formed on a 500 mm plate by sputtering. The film was deposited and formed in a thick layer. The electrode area was 2 mm × 2 mm.

[0114] Here, as a pretreatment, the surface of substrate 500 was washed with water, and then UV ozone treatment was performed for 370 seconds. I went. After that, 10 -4 The substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa. After vacuum firing at 190°C for 60 minutes in the heating chamber of the vacuum deposition apparatus, the substrate 50 I let it cool for about 30 minutes.

[0115] An EL layer 503 and a second electrode 502 are sequentially formed on the first electrode 501. As shown in 5(A), the EL layer 503 of the light-emitting element 1 has a hole injection layer 504 and hole injection Transmitting layer 505, Emitting layer 506 (Emitting layer (I) 506a, Emitting layer (II) 506b), Electron transport The electron-transmitting layer 507 and electron-injection layer 508 are included. Additionally, the light-emitting layer (II) 506b is included. Multiple layers of different materials (506(b1), 506(b2), 506(b3), 506(b 4)) has a laminated structure. Also, as shown in Figure 5(B), the comparative light-emitting element 2 The light-emitting layer 506 has a different configuration from the light-emitting element 1, specifically the light-emitting layer (II) 506b'. In this embodiment, the common parts of the light-emitting element 1 and the comparative light-emitting element 2 will be described together. We will explain only the differences individually.

[0116] The hole injection layer 504 is deposited within the vacuum deposition apparatus at 10 -4 After reducing the pressure to Pa, 1,3,5-tri( Dibenzothiophen-4-yl)-benzene (abbreviation: DBT3P-II) and molybdenum oxide (VI) and DBT3P-II:Molybdenum oxide = 1:0.5 (mass ratio) It was formed on the first electrode 501 by co-depositing. Co-depositing is the process of depositing multiple different materials together. This is a vapor deposition method that simultaneously evaporates from different evaporation sources. In both cases of 2, 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 on the hole transport layer 505, and contains 7-[4-(10-phenyl-9-ammonium [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) is cgDBCzPA:1,6mMemFLPAPrn=1:0. The film was formed by co-depositing to achieve a mass ratio of 0.25. The film thickness was set to 10 nm.

[0119] The light-emitting layer (II) 506b of the light-emitting element 1 shown in Figure 5(A) has a stacked structure consisting of multiple layers. It has, specifically the first layer 506(b1), the second layer 506(b2), the third layer 506( b3) It has a laminated structure consisting of a fourth layer 506 (b4). 2) The third layer 506(b3) and the fourth layer 506(b4) are both composed of e-compounds from the excited complex. This configuration allows for phosphorescence emission based on energy transfer.

[0120] The first layer 506(b1) has 2-[3'-(dibenzothiophenate) on the luminescent layer (I) 506a. [n-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mD) BTBPDBq-II), N-(1,1'-biphenyl-4-yl)-N-[4-(9- Phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-flu Oren-2-amine (abbreviation: PCBBiF) is used in 2mDBTBPDBq-II:PCBB The film was formed by co-deposition with iF = 0.2:0.8 (mass ratio). The film thickness was 2 nm. .

[0121] The second layer 506(b2) is 2mDBTBPDBq-II on the first layer 506(b1), PCBBiF, (acetylacetonato)bis(6-tert-butyl-4-phenylpyryl) Iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]) , 2mDBTBPDBq-II:PCBBiF:[Ir(tBuppm)2(acac) It was formed by co-deposition with a mass ratio of 0.1:0.9:0.06. The film thickness was 5n Let's call it m.

[0122] The third layer 506(b3) is 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- pentandionato-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. The film thickness was set to 5 nm.

[0123] The fourth layer 506(b4) is 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-deposition at a mass ratio of 6. The film thickness was set to 20 nm.

[0124] The light-emitting layer (II) 506b' of the comparative light-emitting element 2 shown in Figure 5(B) is a stacked layer consisting of multiple layers. It has a structure, specifically a first layer 506(b1), a second layer 506(b2'), and a third layer It has a laminated structure consisting of 506(b3'). The first layer 506(b1) is Since it is the same as the first layer 506(b1) in the light-emitting element 1, it can be manufactured in the same manner. I will omit the explanation.

[0125] The second layer 506(b2') is 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 layers were formed by co-deposition with a mass ratio of 1:0.9:0.06. The film thickness was 5 nm. .

[0126] The third layer 506(b3') is 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-deposition to a mass ratio of 0.06. The film thickness was 20 nm.

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

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

[0129] The second electrode 502 is an electrode that functions as a cathode, and has silver (Ag) on ​​the electron injection layer 508. It was co-deposited with magnesium (Mg) in a 1:0.5 (mass ratio) to form a film thickness of 1 nm. Next, silver was deposited to a thickness of 150 nm using the sputtering method. In the vapor deposition process, resistance heating was used for all deposition steps.

[0130] Although not shown in Figure 5, the fabricated light-emitting element 1 and comparative light-emitting element 2 were exposed to the atmosphere. To prevent this, it was sealed inside a glove box under a nitrogen atmosphere (specifically, the sealing material was used Apply to the area around the child and expose to 365nm ultraviolet light at 6J / cm². 2 Irradiate and heat at 80°C for 1 hour. Processed.

[0131] Table 1 shows the element structures of the light-emitting element 1 and comparative light-emitting element 2 obtained as described above. However, For the light-emitting layer (I) 506a in the optical element 1, see * in the table. 1 As shown, the light-emitting layer (II) For the first layer 506(b1) included in 506b, see * in the table. 2 As shown, the second layer 5 For 06(b2), see * in the table. 3 As shown, for the third layer 506(b3), in the table of* 4 As shown, for the fourth layer 506(b4), see * in the table. 5This is shown. Also, comparative emission For the first layer 506(b1) in element 2, see * in the table. 2 As shown, the second layer 506 For (b2'), see * in the table. 6 As shown, for the third layer 506(b3'), in the table... of* 5 This is shown.

[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 attached to the fabricated light-emitting element 1 and the comparative light-emitting element 2. These were bonded to the substrate surface on the side from which light was emitted using a contact solution with a refractive index of 1.78. Regarding the device characteristics, the total luminous flux was measured using an integrating sphere at room temperature (in an atmosphere maintained at 25°C). The results are shown in Table 2 below. Note that the results shown in Table 2 are for 1000 cd / m². 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, the light-emitting element 1 fabricated in this embodiment has a higher external quantum value compared to the comparative light-emitting element 2. It was found to demonstrate efficiency. Furthermore, the correlated color temperature is also defined in the JIS standard for indoor lighting. Incandescent light emission within the specified range (specifically, correlated color temperature of 2600K to 7100K) (2 The results showed that the temperature range was 600K to 3250K.

[0136] Furthermore, 3.75 mA / cm² is supplied to both light-emitting element 1 and comparison light-emitting element 2. 2 A current flows at this current density. Figure 6 shows the emission spectrum at the initial stage of operation. As shown in Figure 6, the light-emitting element 1 and the relative The emission spectra of comparison light-emitting element 2 are all around 470 nm, 547 nm, and 613 nm. It has a peak around m, and the fluorescence emission obtained from the light-emitting layer (I) 506a, and the emission It is suggested that this originates from phosphorescence obtained from layer (II)(506b, 506b'). It can be done.

[0137] Furthermore, the difference in external quantum efficiency when comparing light-emitting element 1 and comparative light-emitting element 2 is as follows: This is thought to be due to the layered structure of the light-emitting layer (II) 506b. This is shown in Figure 6. Furthermore, the light-emitting element 1 has emission peaks around 547 nm and 613 nm, producing green light. This can be explained by the fact that the intensity of the red light emission is greater than that of the comparative light-emitting element 2. .

[0138] In other words, the light-emitting element 1 has a second layer 506(b2) in the light-emitting layer (II) 506b The third layer 506(b3) formed between the fourth layer 506(b4) and the second layer 506 (b2) and emission peaks with longer wavelengths than those obtained from the fourth layer 506 (b4) It is formed to show a curve, and as a result, excitation is generated in the third layer 506(b3). It is thought that the luminescence efficiency increased because the diffusion of the offspring to other layers was suppressed.

[0139] Furthermore, in Figure 6, the intensity of the blue light emission from the light-emitting element 1, which has an emission peak around 470 nm, is shown. Regarding the fact that the intensity is smaller compared to the intensity of comparative light-emitting element 2, the light-emitting layer (II) For the reasons mentioned above, phosphorescence emission in 506b is performed more efficiently, and the light-emitting layer (I This can be explained by the fact that the probability of energy transfer to 506a has decreased.

[0140] As a result of these, the phosphorescence emission in the emission ratio of fluorescence emission to phosphorescence emission of the light-emitting element 1 The ratio is higher compared to comparative light-emitting element 2, which suggests that the external quantum efficiency has increased. .

[0141] Furthermore, the results of the reliability test for the light-emitting element 1 are shown in Figure 7. In Figure 7, the vertical axis represents the initial state. The graph shows the normalized brightness (%) with brightness set to 100%, and the horizontal axis represents the element's operating time (h). Furthermore, the reliability test was conducted with an initial brightness of 5000 cd / m². 2 Set to the following condition: The light-emitting element 1 was driven. As a result, it was found that the light-emitting element 1 is a long-life light-emitting element. .

[0142] Furthermore, an element with the same configuration as the light-emitting element 1 fabricated in this embodiment was placed on a substrate with a refractive index of 1.84. The light area is formed to be 90mm x 90mm, and the side of the substrate from which light is emitted is flossed. By processing the material, a lighting device with a light-emitting area of ​​90mm x 90mm was manufactured. The ITO film thickness of the electrode was set to 70 nm. The fabricated lighting device had a brightness of 1000 cd / m². 2 In the vicinity, the average color rendering index Ra is a good 84, and the power efficiency is 92 lm / W. It demonstrated extremely high efficiency. Furthermore, this lighting device has a color temperature of 2800K, conforming to the standard for incandescent light. They exhibit matching characteristics. [Examples]

[0143] In this embodiment, a light-emitting element 3 is fabricated as a light-emitting element according to one aspect of the present invention, and its characteristics are evaluated. Furthermore, the light-emitting element 3 has the same structure as the light-emitting element 1 shown in Example 1, as shown in Figure 5. As shown in (A), the light-emitting layer (I) 506a is a light-emitting layer that produces fluorescence emission, Layer (II) 506b is an emissive layer that produces phosphorescence. b has a laminated structure, between the second layer 506(b2) and the fourth layer 506(b4) The third layer 506(b3) formed therein is the second layer 506(b2) and the fourth layer 506(b 4) It is formed to show an emission peak with a longer wavelength than the emission peak obtained from 4) Furthermore, the structural formulas and abbreviations of the materials used in this embodiment are shown below.

[0144] [ka]

[0145] [ka]

[0146] <Fabrication of Light-Emitting Device 3> 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 a 500 surface, indium tin oxide (ITSO) containing silicon oxide is applied by sputtering. The film was deposited and formed to a thickness of 70 nm. The electrode area was 81 cm². 2 Furthermore, the light emitted from the substrate... The side facing outwards was given a frosted finish.

[0147] The light-emitting element 3 shown in this embodiment is different from the light-emitting element 1 and comparative light-emitting element 2 shown in Example 1. Since the manufacturing method and other aspects are the same, only the electrode area differs, the characteristic element structure of the light-emitting element 3 is The composition is shown in Table 3 below, and a detailed explanation is omitted. Note that the light-emitting layer (I) 50 Of 6a and the light-emitting layer (II) 506b, the light-emitting layer (I) 506a produces fluorescence emission. The structure is such that the second layer 506(b2) and the third layer 5 are included in the light-emitting layer (II) 506b. Layers 06(b3) and the fourth layer 506(b4) are both derived from the excitation complex, similar to the light-emitting element 1. This configuration provides phosphorescent emission based on energy transfer. Also, in Table 3, light-emitting element 3 For the light-emitting layer (I) 506a, see * in the table. 1 As shown, the luminescent layer (II) 506b contains For the first layer 506(b1) that is included, see * in the table. 2 As shown, the second layer 506(b2) For this, see * in the table. 3 As shown, for the third layer 506(b3), see * in the table. 4 Shown For the fourth layer 506(b4), see * in the table. 5 This is shown.

[0148] [Table 3]

[0149] ≪Element characteristics of light-emitting element 3≫ The element characteristics of the fabricated light-emitting element 3 were measured at room temperature (in an atmosphere maintained at 25°C). The results are shown in Figure 8 and Table 4 below. Note that the results shown in Table 4 are for 1000 cd / m². 2 Nearby These are the main initial characteristic values ​​of the light-emitting element 3.

[0150] [Table 4]

[0151] From the above results, the light-emitting element 3 fabricated in this embodiment is similar to the light-emitting element 1 shown in Example 1. It was found to exhibit high external quantum efficiency. Furthermore, the correlated color temperature is also defined in the JIS standard. Electrical lighting within the specified range for indoor lighting (specifically, correlated color temperature of 2600K to 7100K) The results showed that it emitted a bulbous color (2600K~3250K) light.

[0152] Additionally, 1.2 mA / cm³ is emitted to the light-emitting element 3. 2 When current is passed at this current density, the initial light emission of the drive... The spectral distribution is shown in Figure 9. As shown in Figure 9, the emission spectrum of the light-emitting element 3 is 470 nm. It has peaks around 547nm and 613nm, suggesting that the light-emitting layer (I) 506a... The fluorescence emission obtained from this, and the phosphorescence emission obtained from the light-emitting layer (II) 506b, This suggests that...

[0153] Furthermore, the light-emitting element 3 shown in this embodiment emits strong blue light with an emission peak around 470 nm. Compared to the other values, the intensity of the red emission, which has an emission peak around 613 nm, is very high. Therefore In the light-emitting layer (II) 506b of the light-emitting element 3, the second layer 506(b2) and the fourth layer excitons generated in the third layer 506(b3) formed between 506(b4) and 506(b4) Diffusion to other layers is suppressed, and the proportion of phosphorescence in the emission ratio of fluorescence emission to phosphorescence emission. This is thought to be due to an increase in the external quantum efficiency. [Examples]

[0154] In this embodiment, a light-emitting element 4 is fabricated as a light-emitting element according to one aspect of the present invention, and its characteristics are evaluated. The light-emitting element 4 has a structure similar to the light-emitting element 1 shown in Example 1, as shown in Figure As shown in 5(A), the light-emitting layer (I) 506a is a light-emitting layer that produces fluorescence emission. The light layer (II) 506b is a light-emitting layer that produces phosphorescence. Also, the light-emitting layer (II) 50 6b has a laminated structure, and the second layer 506(b2) and the fourth layer 506(b4) The third layer 506(b3) formed in between the second layer 506(b2) and the fourth layer 506( It is formed to show an emission peak with a longer wavelength than the emission peak obtained from b4). The structural formulas and abbreviations of the materials used in this embodiment are shown below.

[0155] [ka]

[0156] [ka]

[0157] <Fabrication of the light-emitting element 4> The first electrode 501 is an electrode that functions as an anode, and is made of silica oxide on a glass substrate 500. Indium tin oxide (ITSO) containing ions is coated to a thickness of 110 nm by sputtering. The film was deposited and formed using [a specific method]. The electrode area was set to 2 mm × 2 mm.

[0158] The light-emitting element 4 shown in this embodiment is the same as the light-emitting element 1 shown in Embodiment 1 in terms of manufacturing method, etc. Therefore, the characteristic element configuration of the light-emitting element 4 is shown in Table 5 below, and a detailed explanation will be provided later. Omitted. Note that the light-emitting layer (I) 506a and light-emitting layer (II) 506b of the light-emitting element 4 The light-emitting layer (I) 506a is configured to produce fluorescence emission, and the light-emitting layer (II) 506b The second layer 506(b2), the third layer 506(b3), and the fourth layer 506(b4) are included in this. This configuration yields phosphorescence based on energy transfer from the excited complex. See also Table 5. In the table, the light-emitting layer (I) 506a of the light-emitting element 4 is as shown by * 1 As shown, the light-emitting layer (II) For the first layer 506(b1) included in 506b, see * in the table. 2 As shown, the second layer 5 For 06(b2), see * in the table. 3 As shown, for the third layer 506(b3), in the table of* 4 As shown, for the fourth layer 506(b4), see * in the table. 5 This is shown.

[0159] [Table 5]

[0160] <Element characteristics of light-emitting element 4> The element characteristics of the fabricated light-emitting element 4 were measured at room temperature (in an atmosphere maintained at 25°C). The results are shown in Figure 10 and Table 6 below. Note that the results shown in Table 6 are for 1000 cd / m². 2 nearby These are the main initial characteristic values ​​of the light-emitting element 4.

[0161] [Table 6]

[0162] From the above results, it was found that the light-emitting element 4 fabricated in this embodiment exhibits high external quantum efficiency. Furthermore, the correlated color temperature is also within the specified range for indoor lighting as defined in the JIS standard (specifically, Incandescent-colored light (2600K~3250K) with a correlated color temperature of 2600K~7100K. The results showed that...

[0163] Additionally, the light-emitting element 4 receives 3.75 mA / cm². 2 Initial illumination when current is passed at this current density. The spectrum is shown in Figure 11. As shown in Figure 11, the emission spectrum of the light-emitting element 4 is 46 It has peaks around 9nm, 550nm, and 611nm, and the light-emitting layer (I) 50 The fluorescence emission is derived from 6a and the phosphorescence emission is derived from the luminescence layer (II) 506b. This suggests that they are doing so.

[0164] Furthermore, the light-emitting element 4 shown in this embodiment emits a strong blue light with an emission peak around 469 nm. Compared to the other values, the intensity of the red emission, which has an emission peak around 611 nm, is very high. Therefore In the light-emitting layer (II) 506b of the light-emitting element 4, the second layer 506(b2) and the fourth layer excitons generated in the third layer 506(b3) formed between 506(b4) and 506(b4) Diffusion to other layers is suppressed, and the proportion of phosphorescence in the emission ratio of fluorescence emission to phosphorescence emission. This is thought to be due to an increase in the external quantum efficiency.

[0165] Furthermore, an element with the same configuration as the light-emitting element 4 fabricated in this embodiment was placed on a substrate with a refractive index of 1.84. The light area is formed to be 90mm x 90mm, and the side of the substrate from which light is emitted is flossed. By processing the material, a lighting device with a light-emitting area of ​​90mm x 90mm was manufactured. ITO was used for the electrodes, with a thickness of 70 nm. The fabricated lighting device had a brightness of 10 00 cd / m 2 In the vicinity, the average color rendering index Ra is a good 83, and the power efficiency is also 8 It demonstrated high efficiency of 1 lm / W. Furthermore, this lighting device has a color temperature of 3200K, providing warm white light. It exhibits characteristics that conform to 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 Emitting layer (I), 106b 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 Sealant 206 Sealing substrate 207 Wiring 208 FPC (Flexible Printed Circuit) 209 FET 210 FET 211 Switching FET 212 Current-controlled FETs 213 First electrode (anode) 214 Insulators 215 EL layer 216 Second electrode (cathode) 217 Light-emitting element 218 Space 500 circuit boards 501 First electrode 502 Second electrode 503 EL layer 504 Hole injection layer 505 Hole transport layer 506 Emitting layer 506a Emitting layer (I), 506b Emitting layer (II) 506(b1) First layer 506(b2) Second layer 506(b3) Third layer 506(b4) The fourth layer 506b' Emitting layer (II) 506(b2') Second layer 506(b3') Third layer 507 Electron transport layer 508 Electron injection layer 7100 Television equipment 7101 enclosure 7103 Display section 7105 Stand 7107 Display section 7109 Operation Keys 7110 Remote Control Unit 7201 Main Unit 7202 enclosure 7203 Display section 7204 Keyboard 7205 External connection port 7206 Pointing device 7302 enclosure 7304 Display Panel 7305 Icon representing the time 7306 Other icons 7311 Operation Buttons 7312 Operation Buttons 7313 Connection terminal 7321 Band 7322 Clasp 7400 mobile phones 7401 enclosure 7402 Display section 7403 Operation buttons 7404 External connection section 7405 Speaker 7406 Microphone 7407 Camera 7500(1), 7500(2) cabinet 7501(1), 7501(2) 1st page 7502(1), 7502(2) 2nd page 8001 Lighting device 8002 Lighting device 8003 Lighting device 8004 Lighting device

Claims

1. Lens and, Anode and, Cathode and, A first layer, a second layer, a third layer, a fourth layer, and a fifth layer are disposed 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 phosphorescent material. The third layer is located between the second layer and the fourth layer and includes the first phosphorescent material, The fourth layer is located between the third layer and the fifth layer and contains a second phosphorescent material. The fifth layer is located between the fourth layer and the cathode and contains a third phosphorescent material. The emission peak wavelength of the second phosphorescent material is longer than the emission peak wavelength of the first phosphorescent material. The emission peak wavelength of the second phosphorescent material is longer than the emission peak wavelength of the third phosphorescent material. Each of the third, fourth, and fifth layers has two organic compounds that form an excited complex, Light is emitted through the lens. Light-emitting device.

2. Lens and, Anode and, Cathode and, It has a first layer, a second layer, a third layer, a fourth layer, and a fifth layer disposed 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 phosphorescent material. The third layer is located between the second layer and the fourth layer and includes the first phosphorescent material, The fourth layer is located between the third layer and the fifth layer and contains a second phosphorescent material. The fifth layer is located between the fourth layer and the cathode and contains a third phosphorescent material. The emission peak wavelength of the second phosphorescent material is longer than the emission peak wavelength of the third phosphorescent material. Unlike the first and third phosphorescent materials, the second phosphorescent material differs from the first and third phosphorescent materials. Each of the third, fourth, and fifth layers has two organic compounds that form an excited complex, Light is emitted through the lens. Light-emitting device.

3. In claim 1 or claim 2, It has a transistor that has an oxide semiconductor, The transistor is electrically connected to the anode in the light-emitting device.

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