Light-emitting element

Abstract

To provide a multi-color light-emitting element using fluorescence and phosphorescence and being useful for practical application.SOLUTION: A light-emitting element includes a multilayer structure including a first light-emitting layer containing a host material and a fluorescence material, a separation layer containing a material with a hole transport property and a material with an electron transport property, and a second light-emitting layer containing two kinds of organic compounds forming an exciplex and a material that can convert triplet excited energy into light emission. A light-emitting element in which the peak of emission spectrum of the light from the first light-emitting layer exists on a shorter wavelength side than that of the light from the second light-emitting layer is more useful.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One aspect of the present invention relates to a light-emitting element using an organic compound as a light-emitting substance, a display module, a lighting module, a display device, a light-emitting device, an electronic device, and a lighting device.

[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 or the like relates to an article, a method, or a manufacturing method. Alternatively, 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. can be cited.

Background Art

[0003] In recent years, research and development of light-emitting elements (organic EL elements) using electroluminescence (EL) of organic compounds have been actively conducted. The basic configuration of these light-emitting elements is such that an organic compound layer (EL layer) containing a light-emitting substance is sandwiched between a pair of electrodes. By applying a voltage to this element, light emission from the light-emitting substance can be obtained.

[0004] Since such light-emitting elements are self-luminous, they have advantages such as higher visibility of pixels compared to liquid crystal displays and the need for no backlight, and are considered suitable as flat panel display elements. In addition, displays using such light-emitting elements are thin and light ​ The fact that it can be manufactured in large quantities is also a great advantage. Furthermore, it is also characterized by a very fast response speed. This is the case.

[0005] These light-emitting elements can emit light in a planar shape. This is a characteristic that is difficult to obtain with point light sources typified by incandescent lamps and LEDs, or line light sources typified by fluorescent lamps, and thus it has high utility value for lighting and the like. This is a characteristic that is difficult to obtain with point light sources typified by incandescent lamps and LEDs, or line light sources typified by fluorescent lamps, and thus it has high utility value for lighting and the like. This is a characteristic that is difficult to obtain with point light sources typified by incandescent lamps and LEDs, or line light sources typified by fluorescent lamps, and thus it has high utility value for lighting and the like.

[0006] In such an organic EL element, electrons are injected from the cathode and holes are injected from the anode into the EL layer, respectively. When they recombine, the light-emitting organic compound is excited and light emission can be obtained. In such an organic EL element, electrons are injected from the cathode and holes are injected from the anode into the EL layer, respectively. When they recombine, the light-emitting organic compound is excited and light emission can be obtained. In such an organic EL element, electrons are injected from the cathode and holes are injected from the anode into the EL layer, respectively. When they recombine, the light-emitting organic compound is excited and light emission can be obtained.

[0007] As types of excited states formed by organic compounds, there are singlet excited states and triplet excited states. Light emission from the singlet excited state (S ) is called fluorescence, and light emission from the triplet excited state (T * ) is called phosphorescence. And the statistical generation ratio in the light-emitting element is said to be S * :T =1:3. * :T * =1:3.

[0008] In a compound that emits light from the singlet excited state (hereinafter referred to as a fluorescent substance), usually only fluorescence is observed at room temperature and phosphorescence is not observed. Therefore, the theoretical limit of the internal quantum efficiency (the ratio of photons generated with respect to the injected carriers) in a light-emitting element using a fluorescent substance is 25% based on the fact that S :T =1:3. * :T * =1:3.

[0009] On the other hand, if a compound that emits light from the triplet excited state (hereinafter referred to as a phosphorescent compound) is used, Phosphorescence can be observed at room temperature. In addition, since the phosphorescent compound is prone to intersystem crossing (excitation energy transfer from the singlet excited state to the triplet excited state), the internal quantum efficiency theoretically can reach up to 100%. That is, in a light-emitting device using a phosphorescent light-emitting substance, a higher luminous efficiency can be achieved compared to a light-emitting device using a fluorescent light-emitting substance. For these reasons, in recent years, the development of light-emitting devices using phosphorescent compounds has been actively carried out to realize highly efficient light-emitting devices. In Patent Document 1, a white light-emitting device having a light-emitting region containing a plurality of light-emitting dopants and the light-emitting dopants emitting phosphorescence is disclosed. In addition, in Patent Document 2, an element (so-called tandem element) having an intermediate layer (charge generation layer) provided between a fluorescent light-emitting layer and a phosphorescent light-emitting layer is disclosed.

[0010] As a multi-color light-emitting device typified by a white light-emitting device, as in Patent Document 2, a layer (fluorescent light-emitting layer) that emits fluorescence in the short-wavelength region, and a layer that emits phosphorescence in the long-wavelength region (phosphorescent light-emitting layer) are provided, and an element having an intermediate layer (charge generation layer) provided between the fluorescent light-emitting layer and the phosphorescent light-emitting layer has been developed and partially put into practical use. The said element has a light-emitting device with an intermediate layer interposed therebetween.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0012] As a multi-color light-emitting device typified by a white light-emitting device, as in Patent Document 2, a layer (fluorescent light-emitting layer) that emits fluorescence in the short-wavelength region, and a layer that emits phosphorescence in the long-wavelength region (phosphorescent light-emitting layer) are provided, and an element having an intermediate layer (charge generation layer) provided between the fluorescent light-emitting layer and the phosphorescent light-emitting layer has been developed and partially put into practical use. The said element has a light-emitting device with an intermediate layer interposed therebetween. ​​​​​​It has a structure in which two are connected in series.

[0013] In this structure, the light emission on the short-wavelength side, which has concerns about lifespan, is fluorescence, and the light emission on the long-wavelength side is phosphorescence. By doing so, although the luminous efficiency is lower than that of an element that emits only phosphorescence, it is characterized in that a multi-color light-emitting element with stable characteristics can be obtained.

[0014] The multi-color light-emitting element having such a structure is highly reliable and suitable for practical use. However, on the other hand, it also has a disadvantage in practical use that the number of films to be formed to obtain one light-emitting element increases.

[0015] In such an element, there are several reasons for providing an intermediate layer between the phosphorescent light-emitting layer and the fluorescent light-emitting layer. One of them is to prevent the quenching of phosphorescence by the fluorescent light-emitting layer.

[0016] In the fluorescent light-emitting layer, substances having a condensed aromatic ring (especially a condensed aromatic hydrocarbon ring) skeleton typified by anthracene are often used as the host material. This is because when a substance having a condensed aromatic ring skeleton is used as the host material of the fluorescent light-emitting layer, a light-emitting element with stable and good characteristics can be obtained. However, on the other hand, substances having a condensed aromatic ring skeleton generally have a problem of low triplet level. For this reason, when the fluorescent light-emitting layer and the phosphorescent light-emitting layer are provided in contact with each other, the triplet excitation energy generated in the phosphorescent light-emitting layer moves to the triplet level of the host material of the fluorescent light-emitting layer and is deactivated. Since triplet excitons have a long lifespan and a long diffusion distance, not only the excitation energy generated at the interface between the fluorescent light-emitting layer and the phosphorescent light-emitting layer but also the excitation energy generated inside the phosphorescent light-emitting layer is deactivated by the host material of the fluorescent light-emitting layer, resulting in a significant decrease in luminous efficiency.

[0017] On the one hand, if a host material with a large triplet excitation energy is used in the fluorescent emission layer, such problems can be solved. However, since the singlet excitation energy of the host material is larger than the triplet excitation energy of the host material, the energy difference between the singlet excited state of the host material and the singlet excited state of the fluorescent dopant becomes too large, and the energy transfer from the host material to the fluorescent dopant becomes insufficient, so sufficient emission efficiency cannot be obtained in the fluorescent emission layer. Furthermore, as a result, the non-radiative deactivation process of the host material increases, and the characteristics (especially the lifetime) of the device deteriorate. There is also a case. In addition, the fact that the singlet excitation energy of the host material is large means that the HOMO-LUMO gap of the host material is naturally large, which also leads to an increase in the driving voltage. Therefore, in one aspect of the present invention, it is an object to provide a novel light-emitting device. Or, in one aspect of the present invention, in a light-emitting device using fluorescent emission and phosphorescent emission, it is an object to provide a multicolor light-emitting device advantageous for practical use. Also, in a light-emitting device using fluorescent emission and phosphorescent emission, due to the relatively small number of film-forming layers, the manufacturing process is less, and it is an object to provide a multicolor light-emitting device advantageous for practical use. Or, in another aspect of the present invention, in a light-emitting device using fluorescent emission and phosphorescent emission, it is an object to provide a multicolor light-emitting device having good emission efficiency. Or, in another aspect of the present invention, in a light-emitting device using fluorescent emission and phosphorescent emission, the number of film-forming layers is relatively small, which is advantageous for practical use, and a multicolor light-emitting device having good emission efficiency.

[0018]

[0019]

[0020] ​​​​​​​​​​​An object of the present invention is to provide a child. Or, in another aspect of the present invention, to provide a novel light-emitting element. An object is to provide.

[0021] Or, one aspect of the present invention is to provide a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device that can be manufactured at low cost by using the above-described light-emitting element. respectively. An object is to provide each.

[0022] Or, one aspect of the present invention is to provide a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption by using the above-described light-emitting element. respectively. An object is to provide each.

[0023] The present invention only needs to solve any one of the above problems.

Means for Solving the Problems

[0024] A first light-emitting layer including a host material and a fluorescent light-emitting substance, a separation layer, and a second light-emitting layer including two types of organic compounds that form an exciplex and a substance that can convert triplet excitation energy into light emission. The laminated structure can achieve the above problems. Note that the emission from the first light-emitting layer has a peak in the emission spectrum on the shorter wavelength side than the emission from the second light-emitting layer. The light-emitting element is more useful. That is, one aspect of the present invention has a pair of electrodes and an EL layer sandwiched between the pair of electrodes. The EL layer has at least a first light-emitting layer, a second light-emitting layer, and a separation layer provided therebetween. The emission spectrum from the first light-emitting layer exists in a shorter wavelength region than the emission spectrum from the second light-emitting layer. The first light-emitting layer has at least a fluorescent light-emitting substance and a host material.

[0025] That is, one aspect of the present invention has a pair of electrodes and an EL layer sandwiched between the pair of electrodes. The EL layer has at least a first light-emitting layer, a second light-emitting layer, and a separation layer provided therebetween. The EL layer has at least a first light-emitting layer, a second light-emitting layer, and a separation layer provided therebetween. The emission spectrum from the first light-emitting layer is in a shorter wavelength region than the emission spectrum from the second light-emitting layer. The first light-emitting layer has at least a fluorescent light-emitting substance and a host material. The emission spectrum from the first light-emitting layer is in a shorter wavelength region than the emission spectrum from the second light-emitting layer. The first light-emitting layer has at least a fluorescent light-emitting substance and a host material. The emission spectrum from the first light-emitting layer is in a shorter wavelength region than the emission spectrum from the second light-emitting layer. The first light-emitting layer has at least a fluorescent light-emitting substance and a host material. The second light-emitting layer has at least a substance capable of converting triplet excitation energy into light emission, a first organic compound, and a second organic compound, and is a light-emitting device in which the first organic compound and the second organic compound form an exciplex.

[0026] Alternatively, another aspect of the present invention is a light-emitting device having the above configuration, in which the separation layer contains a substance having hole-transporting properties and a substance having electron-transporting properties.

[0027] Alternatively, another aspect of the present invention is a light-emitting device having the above configuration, characterized in that a substance having hole-transporting properties and a substance having electron-transporting properties form a second exciplex.

[0028] Alternatively, another aspect of the present invention is a light-emitting device having the above configuration, in which the thickness of the separation layer is greater than 0 nm and less than or equal to 20 nm.

[0029] Alternatively, another aspect of the present invention is a light-emitting device having the above configuration, in which the thickness of the separation layer is 1 nm or more and 10 nm or less.

[0030] Alternatively, another aspect of the present invention is a light-emitting device having the above configuration, in which the combination of a substance having hole-transporting properties and a substance having electron-transporting properties is the same as the combination of the first organic compound and the second organic compound.

[0031] Alternatively, another aspect of the present invention is a light-emitting device having the above configuration, characterized in that there is energy transfer from the first exciplex to a substance capable of converting triplet excitation energy into light emission.

[0032] ​​​​​​​​Alternatively, another aspect of the present invention is a light-emitting device having the above-described configuration, in which the singlet excitation level of the host material is higher than the singlet excitation level of the fluorescent light-emitting substance, and the triplet excitation level of the host material is lower than the triplet excitation level of the fluorescent light-emitting substance.

[0033] Alternatively, another aspect of the present invention is a light-emitting device having the above-described configuration, in which the triplet excitation level of the host material is lower than the triplet excitation levels of a hole-transporting substance and an electron-transporting substance. This light-emitting device is characterized by this.

[0034] Alternatively, another aspect of the present invention is a light-emitting device having the above-described configuration, in which the host material is a condensed organic compound having an aromatic ring skeleton.

[0035] Alternatively, another aspect of the present invention is a light-emitting device having the above-described configuration, in which the host material is an organic compound having an anthracene skeleton.

[0036] Alternatively, another aspect of the present invention is a light-emitting device having the above-described configuration, in which the host material is an organic compound having an anthracene skeleton, and the fluorescent light-emitting substance is an organic compound having a pyrene skeleton. This light-emitting device is characterized by this.

[0037] Alternatively, another aspect of the present invention is a light-emitting device having the above-described configuration, in which the second light-emitting layer contains substances that can convert triplet excitation energies of n types (n is an integer of 2 or more) having different emission spectra into light emission, the second light-emitting layer is composed of n layers, and each of the n layers contains a substance that can convert a different triplet excitation energy into light emission. This light-emitting device is characterized by this. This light-emitting device is characterized by this.

[0038] Alternatively, another aspect of the present invention is a light-emitting element having the above-described configuration, wherein the second light-emitting layer contains a first phosphorescent light-emitting substance and a second phosphorescent light-emitting substance, each having a different emission spectrum, as substances capable of converting triplet excitation energy into light emission.

[0039] Alternatively, another aspect of the present invention is a light-emitting element having the above-described configuration, wherein the first phosphorescent light-emitting substance exhibits light emission in the red region, the second phosphorescent light-emitting substance exhibits light emission in the green region, and the fluorescent light-emitting substance exhibits light emission in the blue region.

[0040] Alternatively, another aspect of the present invention is a light-emitting element having the above-described configuration, wherein the first phosphorescent light-emitting substance has a peak of the emission spectrum at 580 nm to 680 nm, the second phosphorescent light-emitting substance has a peak of the emission spectrum at 500 nm to 560 nm, and the fluorescent light-emitting substance has a peak of the emission spectrum at 400 nm to 480 nm.

[0041] Alternatively, another aspect of the present invention is a light-emitting element having the above-described configuration, wherein the second light-emitting layer is composed of a first phosphorescent light-emitting layer and a second phosphorescent light-emitting layer, the first phosphorescent light-emitting layer contains the first phosphorescent light-emitting substance, and the second phosphorescent light-emitting layer contains the second phosphorescent light-emitting substance.

[0042] Alternatively, another aspect of the present invention is a light-emitting element having the above-described configuration, wherein the first phosphorescent light-emitting substance exhibits carrier trapping properties within the first phosphorescent light-emitting layer.

[0043] Alternatively, another aspect of the present invention is a light-emitting element having the above-described configuration, wherein carrier trapping ​The property is a light-emitting element characterized by electron trapping property.

[0044] Alternatively, one aspect of the present invention is a display module having the light-emitting element described in any of the above. ule.

[0045] Alternatively, one aspect of the present invention is an illumination module having the light-emitting element described in any of the above. is.

[0046] Alternatively, one aspect of the present invention is a light-emitting device including the light-emitting element described in any of the above and means for controlling the light-emitting element. stage.

[0047] Alternatively, one aspect of the present invention is a display device having the light-emitting element described in any of the above in a display unit and including means for controlling the light-emitting element. element.

[0048] Alternatively, one aspect of the present invention is an illumination device having the light-emitting element described in any of the above in an illumination unit and including means for controlling the light-emitting element. element.

[0049] Alternatively, one aspect of the present invention is an electronic device having the light-emitting element described in any of the above.

[0050] Note that the light-emitting device in this specification includes an image display device using a light-emitting element. Also, a module in which a connector, for example, an anisotropic conductive film or a TCP (Tape Carr ier Package) is attached to the light-emitting element, a module in which a printed wiring board is provided at the tip of the TCP, or a module in which an IC (integrated circuit) is directly mounted on the light-emitting element by the COG (Chip On Glass) method shall all be included in the light-emitting device. Furthermore, a light-emitting device used for lighting fixtures and the like shall also be included.

Advantages of the Invention

[0051] In one aspect of the present invention, a novel light-emitting element can be provided.

[0052] In one aspect of the present invention, in a light-emitting element using fluorescence and phosphorescence, a multi-color light-emitting element with a relatively small number of film-forming layers, which is advantageous for practical use, can be provided. In addition, in another aspect of the present invention, in a light-emitting element using fluorescence and phosphorescence, a multi-color light-emitting element having good luminous efficiency can be provided.

[0053] Also, in another aspect of the present invention, in a light-emitting element using fluorescence and phosphorescence, a multi-color light-emitting element having a relatively small number of film-forming layers, which is advantageous for practical use and has good luminous efficiency, can be provided. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device that can be manufactured at low cost can be provided respectively.

[0054] Also, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc.

[0055] Also, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device that can be manufactured at low cost can be provided respectively. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc.

[0056] Also, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc. In addition, in another aspect of the present invention, by using the above-described light-emitting element, a display module, a lighting module, a light-emitting device, a display device, an electronic device, and a lighting device with reduced power consumption can be provided respectively. Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0058] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and those skilled in the art can easily understand that the form and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention is not interpreted as being limited to the description content of the embodiments shown below.

[0059] A schematic diagram of a light-emitting element according to an aspect of the present invention is shown in FIG. 1(A). The light-emitting element has at least It also has a pair of electrodes (first electrode 101, second electrode 102) and a light-emitting layer 113 in the EL layer 1 and has 03. The light-emitting layer 113 has a structure in which a first light-emitting layer 113a, a separation layer 113b, and a second light-emitting layer 113c are laminated in this order in contact with each other.

[0060] In Fig. 1(A), as the EL layer 103, a hole injection layer 111, a hole transport layer 1 12, an electron transport layer 114, and an electron injection layer 115 are shown, but this laminated structure is an example and the configuration of the EL layer 103 in the light-emitting device of one aspect of the present invention is not limited to this. Also in Fig. 1(A), the first electrode 101 is illustrated as functioning as an anode, and the second electrode 102 is illustrated as functioning as a cathode.

[0061] The first light-emitting layer 113a contains a fluorescent light-emitting substance and a host material, and the second light-emitting layer 1 13c contains a first organic compound, a second organic compound, and a phosphorescent light-emitting substance. Also in the light-emitting layer having this configuration, the first organic compound and the second organic compound are preferably a combination that forms a first excimer complex.

[0062] By having this configuration, from the first light-emitting layer 113a of the light-emitting device, light emission from the fluorescent light-emitting substance and light emission from the phosphorescent light-emitting substance from the second light-emitting layer 113c are both effectively obtained. In the light-emitting device, even if a charge generation layer is not provided between the first light-emitting layer 113a and the second light-emitting layer 113c (even if it is not a tandem device), both fluorescent light emission and phosphorescent light emission can be efficiently obtained. Note that in the light-emitting device, even if a charge generation layer is not provided between the first light-emitting layer 113a and the second light-emitting layer 113c (even if it is not a tandem device), both fluorescent light emission and phosphorescent light emission can be efficiently obtained. In general, a fluorescent light-emitting layer and a phosphorescent light-emitting layer are introduced into the same EL layer without being separated by a charge generation layer and both fluorescent light emission and phosphorescent light emission can be efficiently obtained.

[0063] and introduced into the same EL layer without separating the fluorescent light-emitting layer and the phosphorescent light-emitting layer with a charge generation layer When light is emitted, a significant decrease in luminous efficiency occurs. In the fluorescent light-emitting layer, a substance having a condensed aromatic ring (particularly a condensed aromatic hydrocarbon ring) skeleton typified by anthracene or the like is usually used as a host material. Therefore, the triplet level of the host material of the fluorescent light-emitting layer is low, and the triplet excitation energy generated in the phosphorescent light-emitting layer moves to the fluorescent light-emitting layer and is deactivated non-radiatively, which is one of the causes. At present, in the fluorescent light-emitting layer, it is difficult to obtain a desired emission wavelength, good device characteristics, and reliability by using a substance other than a substance having a condensed aromatic ring skeleton. Therefore, it is difficult to obtain a light-emitting device having good characteristics by using a configuration in which the fluorescent light-emitting layer and the phosphorescent light-emitting layer are introduced into the same EL layer. Substances having a condensed aromatic ring skeleton are used, so the triplet level of the host material of the fluorescent light-emitting layer is low, and the triplet excitation energy generated in the phosphorescent light-emitting layer moves to the fluorescent light-emitting layer and is deactivated non-radiatively, which is one of the reasons. At present, in the fluorescent light-emitting layer, it is difficult to obtain a desired emission wavelength, good device characteristics, and reliability by using a substance other than a substance having a condensed aromatic ring skeleton. Therefore, it is difficult to obtain a light-emitting device having good characteristics by using a configuration in which the fluorescent light-emitting layer and the phosphorescent light-emitting layer are introduced into the same EL layer. Substances having a condensed aromatic ring skeleton are used, so the triplet level of the host material of the fluorescent light-emitting layer is low, and the triplet excitation energy generated in the phosphorescent light-emitting layer moves to the fluorescent light-emitting layer and is deactivated non-radiatively, which is one of the reasons. At present, in the fluorescent light-emitting layer, it is difficult to obtain a desired emission wavelength, good device characteristics, and reliability by using a substance other than a substance having a condensed aromatic ring skeleton. Therefore, it is difficult to obtain a light-emitting device having good characteristics by using a configuration in which the fluorescent light-emitting layer and the phosphorescent light-emitting layer are introduced into the same EL layer. At present, in the fluorescent light-emitting layer, it is difficult to obtain a desired emission wavelength, good device characteristics, and reliability by using a substance other than a substance having a condensed aromatic ring skeleton. Therefore, it is difficult to obtain a light-emitting device having good characteristics by using a configuration in which the fluorescent light-emitting layer and the phosphorescent light-emitting layer are introduced into the same EL layer. At present, in the fluorescent light-emitting layer, it is difficult to obtain a desired emission wavelength, good device characteristics, and reliability by using a substance other than a substance having a condensed aromatic ring skeleton. Therefore, it is difficult to obtain a light-emitting device having good characteristics by using a configuration in which the fluorescent light-emitting layer and the phosphorescent light-emitting layer are introduced into the same EL layer. At present, in the fluorescent light-emitting layer, it is difficult to obtain a desired emission wavelength, good device characteristics, and reliability by using a substance other than a substance having a condensed aromatic ring skeleton. Therefore, it is difficult to obtain a light-emitting device having good characteristics by using a configuration in which the fluorescent light-emitting layer and the phosphorescent light-emitting layer are introduced into the same EL layer.

[0064] Furthermore, since the relaxation time of the triplet excited state is long, the diffusion distance of excitons is long, and most of the excitons generated inside the phosphorescent light-emitting layer also move to the fluorescent light-emitting layer by diffusion, which makes this problem more serious. Furthermore, since the relaxation time of the triplet excited state is long, the diffusion distance of excitons is long, and most of the excitons generated inside the phosphorescent light-emitting layer also move to the fluorescent light-emitting layer by diffusion, which makes this problem more serious. Furthermore, since the relaxation time of the triplet excited state is long, the diffusion distance of excitons is long, and most of the excitons generated inside the phosphorescent light-emitting layer also move to the fluorescent light-emitting layer by diffusion, which makes this problem more serious.

[0065] At present, it may be difficult to obtain a desired emission wavelength, good device characteristics, and reliability by using a substance not having a condensed aromatic ring skeleton. In a light-emitting device in which the fluorescent light-emitting layer and the phosphorescent light-emitting layer are formed close to each other, it has been difficult to obtain good characteristics. At present, it may be difficult to obtain a desired emission wavelength, good device characteristics, and reliability by using a substance not having a condensed aromatic ring skeleton. In a light-emitting device in which the fluorescent light-emitting layer and the phosphorescent light-emitting layer are formed close to each other, it has been difficult to obtain good characteristics. At present, it may be difficult to obtain a desired emission wavelength, good device characteristics, and reliability by using a substance not having a condensed aromatic ring skeleton. In a light-emitting device in which the fluorescent light-emitting layer and the phosphorescent light-emitting layer are formed close to each other, it has been difficult to obtain good characteristics.

[0066] Here, in the light-emitting device according to one aspect of the present embodiment, a first organic compound and a second organic compound form an exciplex in the second light-emitting layer 113c, and triplet excitation energy moves from this exciplex to a phosphorescent light-emitting substance to obtain light emission. By having such a configuration, the above problem can be solved. Here, in the light-emitting device according to one aspect of the present embodiment, a first organic compound and a second organic compound form an exciplex in the second light-emitting layer 113c, and triplet excitation energy moves from this exciplex to a phosphorescent light-emitting substance to obtain light emission. By having such a configuration, the above problem can be solved. Here, in the light-emitting device according to one aspect of the present embodiment, a first organic compound and a second organic compound form an exciplex in the second light-emitting layer 113c, and triplet excitation energy moves from this exciplex to a phosphorescent light-emitting substance to obtain light emission. By having such a configuration, the above problem can be solved. Here, in the light-emitting device according to one aspect of the present embodiment, a first organic compound and a second organic compound form an exciplex in the second light-emitting layer 113c, and triplet excitation energy moves from this exciplex to a phosphorescent light-emitting substance to obtain light emission. By having such a configuration, the above problem can be solved.

[0067] An exciplex is a complex formed by two substances (in one aspect of the present invention, a first organic compound and a second organic compound) ) is an excited state. When the exciplex emits energy, it forms an exciplex and the two substances that were originally separate also behave as the original separate substances. That is, the exciplex has no ground state and energy transfer between exciplexes or energy transfer from other substances to the exciplex is unlikely to occur in principle.

[0068] In the generation of an exciplex in a light-emitting device, the direct formation of an exciplex (electroplex process) is considered to be dominant when a cation of one of the first organic compound and the second organic compound is adjacent to an anion of the other. Also even if one of the first organic compound and the second organic compound is in an excited state, since it quickly takes in the other substance to form an exciplex, most of the excitons in the second light-emitting layer 113c exist as an exciplex. The exciplex has a smaller bandgap than either the first organic compound or the second organic compound. Also, it is preferable to select the first organic compound and the second organic compound so that the triplet excitation energy of the exciplex is smaller than at least one of the triplet excitation energies of the first organic compound and the second organic compound. More preferably, the first organic compound and the second organic compound are selected so that the triplet excitation energy of the exciplex is smaller than the triplet excitation energies of both the first organic compound and the second organic compound. By selecting the first organic compound and the second organic compound in this way, energy transfer from the exciplex to the first organic compound and the second organic compound hardly occurs. Also, as described above, energy transfer between exciplexes hardly occurs either. As a result, the excitation energy of the exciplex is transferred to the phosphorescent material and converted into light emission. Therefore, almost no exciton diffusion occurs in the second light-emitting layer 113c. As a result the above-described problems can be solved.

[0069] Here, when the first light-emitting layer 113a which is a fluorescent light-emitting layer and the second light-emitting layer 1 13c which is a phosphorescent light-emitting layer are in contact with each other, at this interface, although slightly, energy transfer from the exciplex and the phosphorescent dopant to the host material of the first light-emitting layer 113a (particularly triplet-triplet energy transfer) occurs. As described above, since the exciplex is difficult for excitons to diffuse and can easily transfer energy to the phosphorescent dopant, the influence is relatively small. However, when a phosphorescent dopant that contacts the host material of the first light-emitting layer 113a exists at the interface, the host material extinguishes the light emission of the phosphorescent dopant extremely due to energy transfer by the Dexter mechanism. Therefore, by forming the separation layer 113b between the first light-emitting layer 1 13a and the second light-emitting layer 113c, energy transfer at the interface between the first light-emitting layer 1 13a and the second light-emitting layer 113c can also be suppressed, and both phosphorescent light emission and fluorescent light emission can be achieved with better characteristics. Furthermore, in the light-emitting element of one aspect of the present invention, the first light-emitting layer 113a is configured such that singlet excited states can be easily generated by triplet-triplet

[0070] annihilation (T-T annihilation; TTA). Thereby, the triplet excitation energy generated in the first light-emitting layer 113a can be converted into fluorescent light emission within the first light-emitting layer 113a. As a result, this makes it possible to convert the triplet excitation energy generated in the first light-emitting layer 113a into fluorescent light emission within the first light-emitting layer 113a. As a result, Furthermore, the light-emitting element according to one aspect of the present invention can be a light-emitting element with reduced energy loss. In order to facilitate the generation of singlet excited states by TTA, in the first light-emitting layer 113a, the singlet excitation level of the host material is larger than that of the fluorescent substance, and the triplet excitation level of the host material is smaller than that of the fluorescent substance. The host material and the fluorescent substance may be selected accordingly. As a selection of the host material and the fluorescent substance having such a relationship, typically, a combination of a material having an anthracene skeleton as the host material and a material having a pyrene skeleton as the fluorescent substance is suitable. In the first light-emitting layer 113a, the singlet excitation level of the host material is larger than that of the fluorescent substance, and the triplet excitation level of the host material is smaller than that of the fluorescent substance. The host material and the fluorescent substance may be selected accordingly. As a selection of the host material and the fluorescent substance having such a relationship, typically, a combination of a material having an anthracene skeleton as the host material and a material having a pyrene skeleton as the fluorescent substance is suitable. In addition, if the thickness of the first light-emitting layer 113a is too thick, it becomes difficult to obtain light emission from the second light-emitting layer 113c. On the other hand, if the thickness is too thin, it becomes difficult to obtain light emission from the first light-emitting layer 113a. Therefore, the thickness of the first light-emitting layer 113a is preferably 5 nm or more and 20 nm or less. In addition, if the thickness of the first light-emitting layer 113a is too thick, it becomes difficult to obtain light emission from the second light-emitting layer 113c. On the other hand, if the thickness is too thin, it becomes difficult to obtain light emission from the first light-emitting layer 113a. Therefore, the thickness of the first light-emitting layer 113a is preferably 5 nm or more and 20 nm or less.

[0071] In addition, when the first light-emitting layer 113a is formed on the anode side, the first light-emitting layer 113a is preferably a layer having hole transport properties. At this time, it is preferable to use a bipolar material having high hole transport properties as the host material. As such a substance, a material having an anthracene skeleton is preferable. In addition, when the first light-emitting layer 113a is formed on the anode side, the first light-emitting layer 113a is preferably a layer having hole transport properties. At this time, it is preferable to use a bipolar material having high hole transport properties as the host material. As such a substance, a material having an anthracene skeleton is preferable. Furthermore, when the hole trapping property of the fluorescent substance is high (for example, a condensed aromatic amine compound as described later), its concentration is 5% or less, preferably 1% or more and 4% or less, more preferably 1% or more and 3% or less. This is a preferable configuration for obtaining phosphorescent emission and fluorescent emission in a well-balanced and highly efficient manner.

[0072] In addition, when the first light-emitting layer 113a is formed on the anode side, the first light-emitting layer 113a is preferably a layer having hole transport properties. At this time, it is preferable to use a bipolar material having high hole transport properties as the host material. As such a substance, a material having an anthracene skeleton is preferable. Furthermore, when the hole trapping property of the fluorescent substance is high (for example, a condensed aromatic amine compound as described later), its concentration is 5% or less, preferably 1% or more and 4% or less, more preferably 1% or more and 3% or less. This is a preferable configuration for obtaining phosphorescent emission and fluorescent emission in a well-balanced and highly efficient manner. (For example, a condensed aromatic amine compound as described later), its concentration is 5% or less, preferably 1% or more and 4% or less, more preferably 1% or more and 3% or less. This is a preferable configuration for obtaining phosphorescent emission and fluorescent emission in a well-balanced and highly efficient manner. In addition, when the first light-emitting layer 113a is formed on the anode side, the first light-emitting layer 113a is preferably a layer having hole transport properties. When the HOMO is higher than the HOMO of the host material, the hole trapping property occurs.

[0073] The combination of the first organic compound and the second organic compound that forms an exciplex in the second light-emitting layer 113c may be any combination capable of forming an exciplex, but it is more preferable that one is a substance having hole transporting properties and the other is a substance having electron transporting properties. In this case, it becomes easier to form a donor-acceptor type excited state, and an exciplex can be efficiently formed. Further, when the combination of the first organic compound and the second organic compound is constituted by the combination of a substance having hole transporting properties and a substance having electron transporting properties, the carrier balance can be easily controlled by the mixing ratio. Specifically, the range of the substance having hole transporting properties: the substance having electron transporting properties = 1:9 to 9:1 is preferable. Further, since the light-emitting device having such a configuration can easily control the carrier balance, the control of the recombination region can also be easily performed. Furthermore, the light-emitting device according to one aspect of the present invention also has the feature that the emission color can be adjusted by controlling the carrier balance as described above.

[0074] In the second light-emitting layer 113c, by overlapping the absorption band on the lowest energy side of the phosphorescent material with the emission spectrum of the first exciplex, the energy transfer from the first exciplex to the phosphorescent material can be optimized, and a light-emitting device with better luminous efficiency can be obtained. It is preferable that the difference in energy conversion value between the peak wavelength of the absorption band on the lowest energy side of the phosphorescent material and the peak wavelength of the emission spectrum of the exciplex is 0.2 eV or less because the overlap is large. ​​​​​​​​​​​​​This is a novel structure. The lowest energy absorption band of phosphorescent materials is the triplet absorption band. It is preferable to use a thermally activated delayed fluorescence (TDF) instead of a phosphorescent material. TADF (activated delayed fluorescence) material When used, the lowest energy absorption band is preferably a singlet absorption band.

[0075] Note that in the light-emitting element of one embodiment of the present invention, the light-emitting substance contained in the second light-emitting layer 113c is Any substance capable of converting doublet excitation energy into luminescence is suitable. Regarding the part described as phosphorescent material, it is described as TADF material and phosphorescent layer. The above part can be read as a TADF light-emitting layer. The excited state is up-converted to the singlet excited state by a small amount of thermal energy (reverse intersystem exchange). A substance that can emit light (fluorescence) from a singlet excited state efficiently. In addition, the conditions for efficiently obtaining thermally activated delayed fluorescence are triplet and singlet excited states. The energy difference between the levels is 0 eV or more and 0.2 eV or less, preferably 0 eV or more and 0.1 eV or less Both phosphorescent materials and TADF materials have triplet excitation energy It is a substance that can convert light into light.

[0076] In the light emitting device of this embodiment, the recombination region of carriers is not localized but is rather distributed to a certain extent. For this purpose, it is preferable to form each light-emitting layer with a suitable carrier distribution. It is preferable that the first light-emitting layer 113a is disposed on the anode side, and the second light-emitting layer In the case where the first light-emitting layer 113c is formed on the cathode side, the first light-emitting layer 113a is a fluorescent material. The quality has hole trapping properties, and in the second light-emitting layer 113c, the phosphorescent material has electron trapping properties, respectively, which is preferable. In the case of a configuration where the first light-emitting layer 113a is formed on the cathode side and the second light-emitting layer 113c is formed on the anode side, it is the opposite. As a material with high electron trapping properties, there are transition metal complexes (such as iridium complexes and platinum complexes) containing a diazine skeleton such as pyrimidine and pyrazine as ligands. In addition, when the LUMO of the phosphorescent material is lower than that of any of the first organic compound and the second organic compound , the electron trapping property occurs.

[0077] The separation layer 113b may be composed of a single substance, but it is preferably composed of a substance having hole transporting properties and a substance having electron transporting properties. Further, it is more preferable that these are a combination that forms an exciplex. Also, by changing the mixing ratio of the substance having hole transporting properties and the substance having electron transporting properties, as described in the second light-emitting layer 113c , the carrier balance can be easily controlled, and the emission color can be adjusted.

[0078] In addition, the material constituting the separation layer 113b preferably has a singlet excitation energy and a triplet excitation energy that are the same as or higher than those of the host material in the first light-emitting layer 113a. Note that , in the case of a configuration where a second exciplex is formed in the separation layer 113b, as described above , since energy transfer to the exciplex hardly occurs, the singlet excitation energy and the triplet excitation energy of the second exciplex may be lower than those of the host material.

[0079] In addition, the singlet excitation energy and the triplet excitation energy of the material constituting the separation layer 113b - One is that there is no restriction on the singlet excitation energy and triplet excitation energy of the first exciplex in the second light-emitting layer 113c. That is, the singlet excitation energy and triplet excitation energy of the material constituting the separation layer 113b may be higher or lower than the singlet excitation energy and triplet excitation energy of the first exciplex in the second light-emitting layer 113c. Normally, when the excitation energy of the separation layer is lower than the excitation energy of the second light-emitting layer 113c, the light emission of the second light-emitting layer 113c significantly decreases. However, in this configuration, since most of the excitons in the second light-emitting layer 113c exist as exciplexes, exciton diffusion is less likely to occur, and energy loss is small.

[0080] When the separation layer 113b is composed of a hole-transporting material and an electron-transporting material, this combination is a preferable configuration because an increase in driving voltage is suppressed when it is the same as the combination of the first organic compound and the second organic compound constituting the second light-emitting layer 113c. That is, it is preferable that one of the first organic compound and the second organic compound is the same as the hole-transporting material in the separation layer 113b, and the other is the same as the electron-transporting material in the separation layer 113b. That is, it is preferable that the second exciplex formed in the separation layer 113b and the first exciplex formed in the second light-emitting layer 113c are the same exciplex.

[0081] In addition, in this light-emitting element, it is preferable to have a configuration in which the light emission from the first light-emitting layer 113a has a peak on the shorter wavelength side than the light emission from the second light-emitting layer 113c. Since a light-emitting element using a phosphorescent light-emitting material that emits short-wavelength light tends to have early luminance degradation, ​​​​​​​​​​​​​By using a fluorescent material that exhibits light emission at a specific wavelength, a light-emitting device with little luminance degradation can be provided. This is possible. Note that, unlike tandem-type devices, in this light-emitting device, between the first light-emitting layer 113a, which is a fluorescent light-emitting layer, and the second light-emitting layer 113c, which is a phosphorescent light-emitting layer, there is only a separation layer 113b with a thickness of several nanometers. Therefore, the number of layers for forming the EL layer is small, and the layer thickness is also thin, making it cost-effective and suitable for mass production. Also, as described above, since the number of layers for forming the EL layer is small, the film thickness of the EL layer can be made thin, which is also an optically advantageous configuration (a configuration with high light extraction efficiency). Furthermore, the driving voltage is low, and a light-emitting device capable of efficiently obtaining both fluorescence and phosphorescence can be achieved at a driving voltage of 5 V or less. Moreover, even when the fluorescent light-emitting layer and the phosphorescent light-emitting layer are close to each other, since a phosphorescent complex is used in the phosphorescent light-emitting layer as described above, deactivation of triplet excitation energy is less likely to occur, and it is an easy configuration to achieve both phosphorescent light emission and fluorescent light emission. In addition, the light-emitting device in this embodiment can be made into a multicolor light-emitting device by obtaining light with different emission wavelengths from the first light-emitting layer 113a and the second light-emitting layer 113c. By this means, light-emitting devices with various emission colors, in which light emission from a plurality of light-emitting materials is combined, can be obtained.

[0082] Also, such a light-emitting device is also suitable for obtaining white light emission. By making the light from the first light-emitting layer 113a and the second light-emitting layer 113c complementary to each other, white light emission can be obtained. Moreover, by using a plurality of light-emitting substances with different emission wavelengths in either or both of the light-emitting layers, white light emission can be obtained.

[0083] In addition, the light-emitting device in this embodiment can be made into a multicolor light-emitting device by obtaining light with different emission wavelengths from the first light-emitting layer 113a and the second light-emitting layer 113c. By this means, light-emitting devices with various emission colors, in which light emission from a plurality of light-emitting materials is combined, can be obtained. In addition, such a light-emitting device is also suitable for obtaining white light emission. By making the light from the first light-emitting layer 113a and the second light-emitting layer 113c complementary to each other, white light emission can be obtained. Moreover, by using a plurality of light-emitting substances with different emission wavelengths in either or both of the light-emitting layers,

[0084] In addition, such a light-emitting device is also suitable for obtaining white light emission. By making the light from the first light-emitting layer 113a and the second light-emitting layer 113c complementary to each other, white light emission can be obtained. Moreover, by using a plurality of light-emitting substances with different emission wavelengths in either or both of the light-emitting layers, white light emission can be obtained. By using a substance, it is also possible to obtain white light with high color rendering composed of three primary colors or four or more types of light emissions. In this case, each light-emitting layer may be further divided into layers, and different light-emitting substances may be contained in each of the divided layers. The white light-emitting element utilizes phosphorescent light emission, and although it is a light-emitting element with high luminous efficiency, compared with a tandem-type light-emitting element, since the number of film-forming layers is small and the layer thickness is thin, it can be an inexpensive light-emitting element. Also, since the layer thickness is thin, the light extraction efficiency is improved. Subsequently, an example of the detailed structure of the above-described light-emitting element will be described below with reference to FIG. 1(A).

[0085]

[0086] The light-emitting element in this embodiment has an EL layer composed of a plurality of layers between a pair of electrodes. In this embodiment, the light-emitting element is composed of a first electrode 101, a second electrode 102, and an EL layer 103 provided between the first electrode 101 and the second electrode 102. In this form, the first electrode 101 functions as an anode, and the second electrode 102 functions as a cathode. The following description will be made on this basis. Note that this stacking order may be reversed. That is, even if the first light-emitting layer 113a is formed on the cathode side and the second light-emitting layer 113c is formed on the anode side, it may be acceptable.

[0087] Since the first electrode 101 functions as an anode, it is preferably formed using a metal, alloy, conductive compound, or a mixture thereof having a large work function (specifically, 4.0 eV or more). Specifically, for example, indium tin oxide (ITO: Indium Tin Oxide), indium tin oxide containing silicon or silicon oxide,

[0087] Indium oxide-zinc oxide, tungsten oxide, and indium oxide containing zinc oxide ( IWZO) and the like can be mentioned. These conductive metal oxide films are usually formed by sputtering, but may also be produced by applying the sol-gel method or the like. As an example of the production method is, indium oxide-zinc oxide is formed by sputtering using a target in which 1 to 20 wt% of zinc oxide is added to indium oxide and the like. Further, indium oxide containing tungsten oxide and zinc oxide (IWZO) contains 0.5 to 5 wt% of tungsten oxide and 0.1 to 1 wt% of zinc oxide with respect to indium oxide and can also be formed by sputtering using a target. In addition, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or a nitride of a metal material (for example, titanium nitride) and the like can be mentioned. Graphene can also be used . By using the composite material described later for the layer in contact with the first electrode 101 in the EL layer 103, it becomes possible to select the electrode material regardless of the work function. Regarding the laminated structure of the EL layer 103, other than the light emitting layer 113 having the above configuration, there are no particular limitations. For example, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, a charge block layer, an intermediate layer, etc. can be appropriately combined and configured. In the present embodiment

[0088] , the EL layer 103 has a configuration in which a hole injection layer 111, a hole transport layer 112, a light emitting layer 113, an electron transport layer 114, and an electron injection layer 115 are sequentially laminated on the first electrode 101. The materials constituting each layer are specifically shown below. ​​

[0089] The hole injection layer 111 is a layer containing a substance having hole injection properties. Molybdenum oxide, b sodium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. can be used. In addition, phthalocyanine-based compounds such as phthalocyanine (abbreviation: H2Pc) and copper phthalocyanine (CuPC ), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl )-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bi s(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-bi phenyl)-4,4'-diamine (abbreviation: DNTPD), or polythiophene / polystyrene sulfonate (PEDOT T / PSS), etc. polymers can also be used to form the hole injection layer 111.

[0090] Also, as the hole injection layer 111, a composite material in which an acceptor substance is contained in a hole transporting substance can be used. Note that by using a substance in which an acceptor substance is contained in a hole transporting substance, the material for forming the electrode can be selected regardless of the work function of the electrode. That is, not only a material with a large work function but also a material with a small work function can be used as the first electrode 101. Examples of acceptor substances include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation : F4-TCNQ), chloranil, etc. Also, metal oxides belonging to Groups 4 to 8 in the periodic table can be mentioned. Specifically, vanadium oxide , niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, mangan ese oxide, etc. ese oxide, etc. Ngan and rhenium oxide are preferred because they have high electron acceptor properties. Among them, molybdenum oxide is preferred because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

[0091] As substances having hole transporting properties used in the composite material, aromatic amine compounds, carbazo le derivatives, aromatic hydrocarbons, polymer compounds (such as oligomers, dendrimers, polymers, etc.) and various organic compounds can be used. Note that as the organic compound used in the composite material it is preferably a substance having hole transporting properties. Specifically, 10 -6 cm 2 / Vs or more, preferably a substance having a hole mobility of. Hereinafter, organic compounds that can be used as substances having hole transporting properties in the composite material will be specifically listed.

[0092] For example, as aromatic amine compounds, N,N'-di(p-tolyl)-N,N'-dif enyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4- diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N ,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-dif enyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3 ,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc. can be mentioned.

[0093] As carbazole derivatives that can be used in the composite material, specifically, 3-[N- (9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarb Zol (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3 -yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2) , 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino] -9-phenylcarbazole (abbreviation: PCzPCN1), etc. can be mentioned.

[0094] In addition, as carbazole derivatives that can be used in composite materials, there are also 4,4’- di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N- carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl- 9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 1,4-bis 4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, etc. can be used.

[0095] In addition, as aromatic hydrocarbons that can be used in composite materials, for example, 2-tert -butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2- tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3, 5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9 ,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,1 0-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthra cene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAn th), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA) , 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene ne, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7- tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetram hyl-9,10-di(2-naphthyl)anthracene, 9,9’-bianthryl, 10,1 0’-diphenyl-9,9’-bianthryl, 10,10’-bis(2-phenylphenyl yl)-9,9’-bianthryl, 10,10’-bis[(2,3,4,5,6-pentap henyl)phenyl]-9,9’-bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, etc. may be mentioned. Fur thermore, pentacene, coronene, etc. can also be used. Thus, 1×10 -6 cm 2 / Vs or more hole mobility, and it is more preferable to use aromatic hydrocarbons having 14 to 42 carbon atoms.

[0096] Note that the aromatic hydrocarbons that can be used in the composite material may have a vinyl skeleton. Examples of the aromatic hydrocarbon having a vinyl group include 4,4’-bis(2,2- diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2- diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA), etc.

[0097] In addition, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphe nylamine) (abbreviation: PVTPA), poly[N-(4-{N’-[4-(4-diphenyl amino)phenyl]phenyl-N’-phenylamino}phenyl)methacrylamide]( ​​Abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis (phenyl)benzidine](abbreviation: Poly-TPD), etc., can also be used for this.

[0098] By forming a hole injection layer, the injectability of holes becomes good, and it becomes possible to obtain a light-emitting element with a small driving voltage.

[0099] The hole transport layer 112 is a layer containing a substance having hole transport properties. Examples of substances having hole transport properties include, for example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]bi phenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N'-diphe nyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4 ''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]trip henylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-bip luoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phe nyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPA FLP), etc., such as aromatic amine compounds, can be used. The substances described here have high hole transport properties and are substances mainly having a hole mobility of 10 cm / Vs or more. Also, -6 cm 2 The organic compounds listed as substances having hole transport properties in the above composite materials can also be used for the hole transport layer 1 112. Also, poly(N-vinylcarbazole) (abbreviation: PVK) or Using a polymer compound such as poly(4-vinyltriphenylamine) (abbreviation: PVTPA), etc. This is also possible. Note that the layer containing a hole transporting material may be not only a single layer but also a laminate of two or more layers composed of the above materials.

[0100] In the light-emitting device according to one embodiment of the present invention, when the first light-emitting layer 113a is provided on the anode side, the HOMO level of the material used for the hole transport layer 112 and the HOMO level of the host material in the first light-emitting layer 113a are preferably close (the energy difference is 0.2 eV or less). By this, holes can flow into the separation layer 113b or the second light-emitting layer 113c without being trapped too much in the trap level, so that fluorescence emission and phosphorescence emission can be balanced and it becomes easy to obtain with good efficiency.

[0101] The light-emitting layer 113 has the above-described configuration. That is, from the first electrode side, the first light-emitting layer 1 13a, the separation layer 113b, and the second light-emitting layer 113c are laminated. Further, the first light-emitting layer 113a contains a host material and a fluorescent light-emitting substance, and the second light-emitting layer 113 c contains a first organic compound, a second organic compound, and a substance capable of converting triplet excitation energy into light emission (phosphorescent compound or TADF material).

[0102] In the first light-emitting layer 113a, examples of materials that can be used as the fluorescent light-emitting substance include the following. Also, various other fluorescent light-emitting substances can be used.

[0103] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine Gin (abbreviation: PAP2BPy), 5,6-bis[4’-(10-phenyl-9-anthryl yl)biphenyl-4-yl]-2,2’-bipyridine (abbreviation: PAPP2BPy), N, N’-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N’ -diphenyl-pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N’- bis(3-methylphenyl)-N,N’-bis[3-(9-phenyl-9H-fluorene -9-yl)phenyl]-pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAP rn), N,N’-bis[4-(9H-carbazol-9-yl)phenyl]-N,N’ -diphenylstilbene-4,4’-diamine (abbreviation: YGA2S), 4-(9H-carb azol-9-yl)-4’-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4’-(9,10-di phenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-di phenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbaz ol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-ter t-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4’ -(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCB APA), N,N’’-(2-tert-butylanthracene-9,10-diyl-di-4 ,1-phenylene)bis[N,N’,N’-triphenyl-1,4-phenylenediamine (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl- 2-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA ), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N’,N’ -triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N’ ,N’,N’’,N’’,N’’’,N’’’-octaphenyldibenz[g,p]chry sene-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-carbazol-9-yl) phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N, N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA) Coumarin 54 5T, N,N’-diphenylquinacridone, (abbreviation: DPQd), Rubrene, 5,12- bis(1,1’-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: B PT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl -4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-me Chile-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinoli din-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation : DCM2), N,N,N’,N’-tetrakis(4-methylphenyl)tetracene-5 ,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N’,N ’-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3, 10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1 ,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[i j]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinit ril (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7 -tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidi ne-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl }-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{ 2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7- tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H- pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM) and the like are mentioned. In particular, condensed aromatic diamine compounds represented by pyrenediamine compounds such as 1,6FLPAPrn and 1,6mMemFLPAPrn have high hole trapping properties and are preferable because of their excellent luminous efficiency and reliability.

[0104] ​​ In the first light-emitting layer 113a, examples of a substance that can be used as a host material include For example, the following can be mentioned:

[0105] 9-Phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-ca PCzPA (abbreviation: PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl PCPN, 9-[4-(10-phenyl-9-anthylene 7-[4-(10- Phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation :cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl ]-Benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl 10-{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl Examples of anthracene compounds include anthracene compounds such as anthracene (abbreviation: FLPPA). When a substance having a cesene skeleton is used as a host material, a light-emitting layer having good light-emitting efficiency and durability can be obtained. In particular, CzPA, cgDBCzPA, 2mBnfPPA, PCzPA is the preferred choice as it exhibits very good properties.

[0106] In the second light-emitting layer 113c, a material capable of converting triplet excitation energy into light emission The materials that fall under this category are phosphorescent materials and TADF materials, for example: can be done.

[0107] The phosphorescent material is tris{2-[5-(2-methylphenyl)-4-(2,6- Dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl- {κC}iridium(III) (abbreviation: Ir(mpptz-dmp)3), tris(5-methyl ethyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III)( Abbreviation: Ir(Mptz)3), tris[4-(3-biphenyl)-5-isopropyl-3 -phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(i Organometallic iridium complexes with 4H-triazole skeletons such as Prptz-3b)3) The body and tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2 ,4-Triazolate]iridium(III) (abbreviation: Ir(Mptz1-mp)3), Tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)i 1H-Triazolium such as iridine(III) (abbreviation: Ir(PrptZ1-Me)3) Organometallic iridium complexes with fac-tris[1-(2,6-diisopropyl] (2-phenyl-1H-imidazole)iridium(III) (abbreviation: I r(iPrpmi)3), tris[3-(2,6-dimethylphenyl)-7-methylimide Dazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: Ir(dmpi Organometallic iridium complexes with imidazole skeletons such as mpt-Me)3) and bis(trifluoromethyl) [2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]Iridium (II I) Tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6 '-Difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) picolinate (Abbreviation: FIrpic), bis{2-[3’,5’-bis(trifluoromethyl)phenyl pyridinato-N,C 2’}iridium(III) picolinate (Abbreviation: Ir(CF3 ppy)2(pic)), bis[2-(4’,6’-difluorophenyl)pyridinato- N,C 2’ iridium(III) acetylacetonate (Abbreviation: FIracac), and the like, organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand are exemplified. These are compounds that exhibit blue phosphorescent emission and are compounds having a peak of emission at 440 nm to 520 n m.

[0108] In addition, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (Abbreviation: Ir(mppm)3), tris(4-t-butyl-6-phenylpyrimidinato)iridium ium(III) (Abbreviation: Ir(tBuppm)3), (acetylacetonato)bis(6-me thyl-4-phenylpyrimidinato)iridium(III) (Abbreviation: Ir(mppm)2( acac)), bis[2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl l-κC](2,4-pentanedionato-κ 2 O,O’)iridium(III) (Abbreviation: Ir(tBuppm)2(acac)), (acetylacetonato)bis[4-(2-nor bornil)-6-phenylpyrimidinato]iridium(III) (endo-, exo- mixture) (Abbreviation: Ir(nbppm)2(acac)), (acetylacetonato)bis 5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(I II) (Abbreviation: Ir(mpmppm)2(acac)), (acetylacetonato)bis( 4,6-diphenylpyrimidinato)iridium(III) (abbreviation: Ir(dppm)2( acac)), an organometallic iridium complex having a pyrimidine skeleton, and (acetyl acetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)( abbreviation: Ir(mppr-Me)2(acac), (acetylacetonato)bis(5-iso propyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir( mppr-iPr)2(acac)), an organometallic iridium complex having a pyrazine skeleton, and tris(2-phenylpyridinato-N,C )iridium(III)( 2’ ) (abbreviation: I r(ppy)3), bis(2-phenylpyridinato-N,C 2’ )iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(acac)), bis(benzo[h]qui nolinato)iridium(III) acetylacetonate (abbreviation: Ir(bzq)2(ac ac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bz q)3), tris(2-phenylquinolinato-N,C 2’ )iridium(III) (abbreviation :Ir(pq)3), bis(2-phenylquinolinato-N,C 2’ )iridium(III ) acetylacetonate (abbreviation: Ir(pq)2(acac)), an organometallic iridium complex having a pyridine skeleton, and tris(acetylacetonato)(monophenantro line)terbium(III) (abbreviation: Tb(acac)3(Phen)), a rare earth metal complex. These are mainly compounds that exhibit green phosphorescent emission and have an emission peak at 500 nm to 600 nm. In addition, an organometallic iridium having a pyrimidine skeleton complex, and ​The uranium complex is particularly preferred because it is outstanding in terms of reliability and luminous efficiency.

[0109] Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrim dinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis 4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium m(III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-di(naphtha len-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation :Ir(d1npm)2(dpm)) and other organometallic iridium complexes having a pyrimidine skeleton, (acetylacetonato)bis(2,3,5-triphenylpyrazinato)irid ium(III) (abbreviation: Ir(tppr)2(acac)), bis(2,3,5-trip henylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tp pr)2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophen yl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac) ), and other organometallic iridium complexes having a pyrazine skeleton, tris(1-phenyliso quinolinato-N,C 2’ )iridium(III) (abbreviation: Ir(piq)3), bis(1 -phenylisoquinolinato-N,C 2’ )iridium(III) (abbreviation: Ir(piq) 2(acac)), and other organometallic iridium complexes having a pyridine skeleton, in addition to 2,3, 7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum( II) (abbreviation: PtOEP) and other platinum complexes, tris(1,3-diphenyl-1,3 -Propanedionato)(monophenanthroline)europium(III)(abbreviation: Eu( DBM)3(Phen)), tris[1-(2-thenoyl)-3,3,3-trifluoro acetonato](monophenanthroline)europium(III)(abbreviation: Eu(TTA) 3(Phen)) and other rare earth metal complexes. These are compounds that exhibit red phosphorescent emission and have an emission peak in the range of 600 nm to 700 nm. In addition, organometallic iridium complexes having a pyrazine skeleton can obtain red emission with good chromaticity.

[0110] In addition to the phosphorescent compounds described above, various phosphorescent emission materials can also be selected and used. That's fine.

[0111] The following can be used as TADF materials.

[0112] Fullerene and its derivatives, acridine derivatives such as proflavine, eosin, etc. Also, metals such as magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt) , indium (In), or palladium (Pd) containing metal-containing porphyrins. Examples of the metal-containing porphyrins include, for example, protoporphyrin- tin fluoride complex (SnF2(Proto IX)) shown by the following structural formula, mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(H emato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (S nF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)) Octaethylporphyrin-platinum chloride complex (PtCl2OEP) etc. can also be mentioned. .

[0113]

Chemical formula

[0114] Also, 2-(biphenyl-4-yl)-4,6-bis(12-flu enylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine ( PIC-TRZ) etc. heterocyclic compounds having a π-electron excess type heteroaromatic ring and a π-electron deficient type heteroaromatic ring can also be used. Since the heterocyclic compound has a π-electron excess type heteroaromatic ring and a π-electron deficient type heteroaromatic ring, it has high electron transport property and hole transport property, which is preferable. Note that a substance in which a π electron excess type heteroaromatic ring and a π-electron deficient type heteroaromatic ring are directly bonded has both strong donor property of the π-electron excess type heteroaromatic ring and acceptor property of the π-electron deficient type heteroaromatic ring, and the energy difference between the S1 level and the T1 level becomes small, so it is particularly preferable.

[0115]

Chemical formula

[0116] As materials that can be used as the above-mentioned first organic compound and second organic compound, there is no particular limitation as long as it is a combination that satisfies the above mentioned conditions, and various carrier transport materials can be selected.

[0117] For example, as substances having electron transport property, bis(10-hydroxybenzo[h]quinoline ato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato )(4-Phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8- quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl) phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl) phenolato]zinc(II) (abbreviation: ZnBTZ) and other metal complexes, 2-(4-bipheny ryl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation : PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylph enyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-te rt-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl) phenyl]-9H-carbazole (abbreviation: CO11), 2,2’,2’’-(1,3,5 -benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TP BI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H -benzimidazole (abbreviation: mDBTBIm-II) and other heterocyclic compounds having a polyazole skeleton, 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzof ,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3’-(dibenzothi ophen-4-yl)biphenyl-3-yl]dibenzof,h]quinoxaline (abbreviation: 2 mDBTBPDBq-II), 2-[3’-(9H-carbazol-9-yl)bipheny yl-3-yl]dibenzof,h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6 -bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPn -bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPn P2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation : 4,6mDBTP2Pm-II), and other heterocyclic compounds having a diazine skeleton, 3,5 -bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCz PPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmP yPB), and other heterocyclic compounds having a pyridine skeleton can be mentioned. Among those described above, the dia heterocyclic compounds having a diazine skeleton and heterocyclic compounds having a pyridine skeleton have good reliability and are preferable. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton have high electron transport properties and contribute to reducing the driving voltage.

[0118] Also, as substances having hole transport properties, 4,4'-bis[N-(1-naphthyl)-N- phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl) -N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TP D), 4,4'-bis[N-(spiro-9,9'-bifluorene-2-yl)-N-phen ylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylflu oren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'- (9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine mine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H -carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1 -Naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine amine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl -9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9 -dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl )phenyl]-fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4 -(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bif luorene-2-amine (abbreviation: PCBASF), etc. compounds having an aromatic amine skeleton and , 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-c arbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl )-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9 H-carbazole) (abbreviation: PCCP), etc. compounds having a carbazole skeleton, 4, 4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation : DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoro rene-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4- [4-(9-phenyl-9H-fluorene-9-yl)phenyl]-6-phenyldibenz othiophene (abbreviation: DBTFLP-IV), etc. compounds having a thiophene skeleton, 4 ,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluorene-9-yl) phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), etc. furan Examples of the compound having a skeleton include. Among those described above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferable because they have good reliability, high hole transportability, and contribute to reducing the driving voltage.

[0119] In addition to the carrier transport materials described above, carrier transport materials may be used from among various substances. Note that as the first organic compound and the second organic compound, it is preferable to select a substance having a triplet level larger than the triplet level (energy difference between the ground state and the triplet excited state) of the phosphorescent compound. Further, it is preferable to select a combination of the first organic compound and the second organic compound that forms an exciplex exhibiting light emission overlapping with the wavelength of the absorption band on the lowest energy side of the phosphorescent material.

[0120] Furthermore, by using a substance having electron transporting properties for one of the combinations of the first organic compound and the second organic compound and a substance having hole transporting properties for the other, a configuration advantageous for the formation of an exciplex can be achieved. Also, by changing the content of these compounds, the transportability of the light emitting layer can be easily adjusted, and the control of the recombination region can also be easily performed. The ratio of the content of the substance having hole transporting properties to the content of the substance having electron transporting properties may be such that the substance having hole transporting properties: the substance having electron transporting properties = 1:9 to 9:1.

[0121] As the material constituting the separation layer 113b, the materials listed as the materials that can be used as the first organic compound and the second organic compound can be used in the same manner.

[0122] The second light-emitting layer 113c may be further divided into two or more layers, and it is preferable that each layer contains different light-emitting substances. In particular, when the second light-emitting layer 113c is divided into two layers, namely the first phosphorescent light-emitting layer and the second phosphorescent light-emitting layer, and red light emission (light emission having a peak in the emission spectrum at 580 nm to 680 nm) is obtained from the first phosphorescent light-emitting layer, and green light emission (light emission having a peak in the emission spectrum at 500 nm to 560 nm) is obtained from the second phosphorescent light-emitting layer, and blue light emission (light emission having a peak in the emission spectrum at 400 nm to 480 nm) is obtained from the first light-emitting layer 113a, a white light emission with good color rendering can be obtained, so this is a preferable configuration. In this case, the stacking order of each light-emitting layer is preferably the first light-emitting layer 113a, the first phosphorescent light-emitting layer, and the second phosphorescent light-emitting layer from the viewpoint of the durability of the light-emitting element. Furthermore, it is preferable that the first light-emitting layer 113a is formed on the anode side to obtain better characteristics. The electron transport layer 114 is a layer containing a substance having electron transporting properties. For example, tris(8-quinolinolato)aluminum (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (abbreviation: BAlq), etc., and is a layer composed of a metal complex having a quinoline skeleton or a benzoquinoline skeleton. In addition, among others, bis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)2), bis[2-(2-

[0123] ​​​​​​​​​​​​​​​​(Hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ)2) and other oxa Metallic complexes having oxazole-based and thiazole-based ligands can also be used. Furthermore, gold In addition to metallic complexes, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)- 1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert -butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OX D-7), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphen nyl)-1,2,4-triazole (abbreviation: TAZ), bathophenanthroline (abbreviation: B Phen), bathocuproin (abbreviation: BCP), etc. can also be used. The substances described here have high electron transport properties and mainly have an electron mobility of 10 -6 cm 2 / Vs or more. Note that the above-described substances having electron transport properties may be used for the electron transport layer 114. In addition, the electron transport layer 114 may be not only a single layer but also a laminate of two or more different layers made of the above substances.

[0124] Also, a layer for controlling the movement of electron carriers may be provided between the electron transport layer and the light emitting layer. This is a layer in which a small amount of a substance having high electron trapping properties is added to the above-described substance having electron transport properties, and by suppressing the movement of electron carriers, it is possible to adjust the carrier balance.

[0125] Such a configuration has a great effect on suppressing problems (for example, a decrease in the device lifetime) caused by electrons passing through the light emitting layer.

[0126] ​​​​Also, an electron injection layer 115 may be provided between the electron transport layer 114 and the second electrode 102 in contact with the second electrode 102 for electrons. As the electron injection layer 115, alkali metals such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), etc., or alkaline earth metals or their compounds can be used. For example, by incorporating an alkali metal, an alkaline earth metal, or their compounds into a layer made of a substance having electron transport properties, it can be used. Note that as the electron injection layer 115, it is more preferable to use a layer made of a substance having electron transport properties and containing an alkali metal or an alkaline earth metal, because electron injection from the second electrode 102 can be efficiently performed.

[0127] As the material for forming the second electrode 102, metals, alloys, electrically conductive compounds, and mixtures thereof having a small work function (specifically, 3.8 eV or less) can be used. Specific examples of such cathode materials include alkali metals such as lithium (Li) and cesium (Cs), and elements belonging to Group 1 or Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), strontium (Sr), and alloys containing these (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these. However, by providing an electron injection layer between the second electrode 102 and the electron transport layer, regardless of the work function, various conductive materials such as Al, Ag, ITO, indium tin oxide containing silicon or silicon oxide, etc. can be used as the second electrode 102. These conductive materials can be formed by sputtering or evaporation methods. electrode 102. It is possible to form a film using the inkjet method, spin coating method, etc.

[0128] Moreover, as a method for forming the EL layer 103, various methods can be used regardless of whether it is a dry method or a wet method. For example, a vacuum evaporation method, an inkjet method, a spin coating method, etc. may be used. Also, different film formation methods may be used for each electrode or each layer. .

[0129] Regarding the electrodes, they may be formed by a wet method using the sol-gel method, or may be formed by a wet method using a paste of a metal material. Also, they may be formed by a dry method such as a sputtering method or a vacuum evaporation method. .

[0130] Light emission is taken out to the outside through either one or both of the first electrode 101 and the second electrode 102. Therefore, either one or both of the first electrode 101 and the second electrode 102 are made of a translucent electrode. When only the first electrode 101 is a translucent electrode, light emission is taken out through the first electrode 101. Also, when all of the second electrode 102 is a translucent electrode, light emission is taken out through the second electrode 102. When both the first electrode 101 and the second electrode 102 are translucent electrodes, light emission is taken out from both through the first electrode 101 and the second electrode 102. Note that the configuration of the layer provided between the first electrode 101 and the second electrode 102 is not limited to the above. However, so as to suppress quenching caused by the light emitting region being in close contact with the metal used for the electrode or the carrier injection layer, the first electrode 101 and the second electrode

[0131] are provided. However, so as to suppress quenching caused by the light emitting region being in close contact with the metal used for the electrode or the carrier injection layer, the first electrode 101 and the second electrode are provided. It is preferable to have a configuration in which a light-emitting region where holes and electrons recombine is provided at a site away from 102.

[0132] In addition, the hole transport layer or electron transport layer in contact with the light-emitting layer 113, particularly the carrier transport layer in contact closer to the light-emitting region in the light-emitting layer 113, suppresses energy transfer from the excitons generated in the light-emitting layer. Therefore, it preferably consists of a material having a band gap larger than the band gap of the light-emitting substance constituting the light-emitting layer or the light-emitting center substance contained in the light-emitting layer. It is preferably composed of a material having a band gap larger than the band gap of the light-emitting substance constituting the light-emitting layer or the light-emitting center substance contained in the light-emitting layer.

[0133] The light-emitting element in this embodiment may be fabricated on a glass substrate, a quartz substrate, a semiconductor substrate, a plastic substrate (such as polyester, polyolefin, polyamide (nylon, aramid, etc.), polyimide, polycarbonate, or acrylic resin). Further, it may be fabricated on a glass substrate, a quartz substrate, or a semiconductor substrate and then transferred to a plastic substrate.

[0134] The light-emitting device may be one in which one light-emitting element is formed on a single substrate, but it may also be one in which a plurality of light-emitting elements are formed. By fabricating a plurality of such light-emitting elements on a single substrate, it is possible to fabricate a lighting device or a passive matrix type light-emitting device in which the elements are divided. In addition, for example, a field effect transistor (FET) may be formed on a substrate made of glass, plastic, etc., and a light-emitting element may be fabricated on an electrode electrically connected to the FET. Thereby, an active matrix type light-emitting device that controls the driving of the light-emitting element by the FET can be fabricated. Note that the structure of the FET is not particularly limited. Also, the crystallinity of the semiconductor used for the FET is not particularly limited, and an amorphous semiconductor or a crystalline semiconductor may be used. Also, the crystallinity of the semiconductor used for the FET is not particularly limited, and an amorphous semiconductor or a crystalline semiconductor may be used. Also, ​Regarding the driving circuit formed on the FET substrate, it may also be composed of N-type and P-type FETs or may be composed of only one of N-type FETs or P-type FETs. It may be either.

[0135] Note that this embodiment can be appropriately combined with other embodiments.

[0136] Subsequently, an embodiment of a light-emitting element having a structure in which a plurality of light-emitting units are stacked (hereinafter also referred to as a stacked element) will be described with reference to FIG. 1(B). This light-emitting element is a light-emitting element having a plurality of light-emitting units between a first electrode and a second electrode. One light-emitting unit has the same configuration as the EL layer 103 shown in FIG. 1(A). That is, the light-emitting element shown in FIG. 1(A) is a light-emitting element having one light-emitting unit, and in this embodiment, it can be said to be a light-emitting element having a plurality of light-emitting units.

[0137] In FIG. 1(B), between the first electrode 501 and the second electrode 502, a first light-emitting unit 511 and a second light-emitting unit 512 are stacked, and a charge generation layer 513 is provided between the first light-emitting unit 511 and the second light-emitting unit 512. The first electrode 501 and the second electrode 502 respectively correspond to the first electrode 101 and the second electrode 102 in FIG. 1(A), and the same ones as those described in the description of FIG. 1(A) can be applied. Also the first light-emitting unit 511 and the second light-emitting unit 512 may have the same configuration or different configurations.

[0138] The charge generation layer 513 contains a composite material of an organic compound and a metal oxide. This organic The composite material of a compound and a metal oxide can be used for the hole injection layer 111 shown in Fig. 1(A). A composite material that can be used can be used. When the surface on the anode side of the light emitting unit is in contact with the charge generation layer, the charge generation layer can also serve as the hole transport layer of the light emitting unit. Therefore, the light emitting unit does not necessarily need to be provided with a hole transport layer.

[0139] Note that the charge generation layer 513 may be formed as a laminated structure combining a layer containing a composite material of an organic compound and a metal oxide and a layer composed of other materials. For example, it may be formed by combining a layer containing a composite material of an organic compound and a metal oxide and a layer containing a compound selected from electron donating substances and a substance having electron transporting properties. Alternatively, it may be formed by combining a layer containing a composite material of an organic compound and a metal oxide and a transparent conductive film.

[0140] In Fig. 1(B), a light emitting device having two light emitting units was described, but the same can be similarly applied to a light emitting device in which three or more light emitting units are laminated. By arranging a plurality of light emitting units between a pair of electrodes with a charge generation layer interposed therebetween as in the light emitting device according to the present embodiment, high-intensity light emission can be achieved while keeping the current density low. As a result, a light emitting device that can be driven at a low voltage and has low power consumption can be realized.

[0141] Note that, in at least one of the plurality of units, since the configuration of the light emitting layer 113 is used, the manufacturing process of the unit can be reduced, so that a multi-color light emitting device advantageous for practical use can be provided.

[0142] Note that the above configuration can be appropriately combined with other embodiments and other configurations in the present embodiment.​​​​​​​​​​​ is possible.

[0143] (Light-emitting device) Next, a light-emitting device according to one embodiment of the present invention will be described.

[0144] The light-emitting device according to one embodiment of the present invention is a light-emitting device manufactured using the above-described light-emitting element. In addition, FIG. 2(A) is a top view showing the light-emitting device, and FIG. 2(B) is a cross-sectional view taken along lines A-B and C- D of FIG. 2(A). This light-emitting device includes a drive circuit section (source line drive circuit) 601, a pixel section 602, and a drive circuit section (gate line drive circuit) 603, which are indicated by dotted lines. Further, 604 is a sealing substrate, and 605 is a sealing material. The inside surrounded by the sealing material 605 is a space 607. The space 607 may be filled with a dried inert gas or a resin for solid sealing. The sealing material 605 and the resin for solid sealing may be the same or different.

[0145] The routing wiring 608 is a wiring for transmitting signals input to the source line drive circuit 601 and the gate line drive circuit 603. It receives a video signal, a clock signal, a start signal, a reset signal, etc. from an FPC (flexible printed circuit) 609 serving as an external input terminal. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to this FPC. The light-emitting device in this specification includes not only the light-emitting device main body but also a state in which an FPC or a PWB is attached thereto.

[0146] Next, the cross-sectional structure will be described with reference to FIG. 2(B). On the element substrate 610, there is a drive circuit. Although a driving circuit section and a pixel section are formed, here, the source line driving circuit 601 which is a driving circuit section and one pixel in the pixel section 602 are shown.

[0147] Note that the source line driving circuit 601 is formed of a CMOS circuit which combines an n-channel type FET 623 and a p-channel type FET 62 4. Also, the driving circuit may be formed of various CMOS circuits , a PMOS circuit or an NMOS circuit. Also, in the present embodiment, although a driver integrated type in which the driving circuit is formed on the substrate is shown, it is not necessarily required, and the driving circuit can also be formed outside rather than on the substrate .

[0148] Also, the pixel section 602 is formed of a plurality of pixels including a switching FET 611, a current control FET 612, and a first electrode 613 electrically connected to its drain. Note that an insulator 614 is formed covering an end portion of the first electrode 613. Here, it is formed by using a positive type photosensitive acrylic resin film.

[0149] Also, in order to make the covering property good, a curved surface having a curvature is formed at an upper end portion or a lower end portion of the insulator 614 . For example, when using a positive type photosensitive acrylic as the material of the insulator 614 , it is preferable to provide a curved surface having a radius of curvature (0.2 μm to 3 μm) only at the upper end portion of the insulator 614. Also, as the insulator 614, either a negative type photosensitive resin , or a positive type photosensitive resin can be used.

[0150] An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613 . Here, as the material used for the first electrode 613 which functions as an anode, the work function ​It is desirable to use a large material. For example, an ITO film, indium tin oxide film containing silicon, indium oxide film containing 2 to 20 wt% of zinc oxide, titanium nitride film , chromium film, tungsten film, Zn film, Pt film, etc., and in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum , a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. When a laminated structure is used, the resistance as a wiring is low, good ohmic contact can be obtained, and it can further function as an anode . In addition, the EL layer 616 is formed by various methods such as vapor deposition using a vapor deposition mask, inkjet method, spin coating method, etc. The EL layer 616 includes the configuration as described in FIG. 1(A) or (B). As other materials constituting the EL layer 616, a low molecular weight compound or a high molecular weight compound (including oligomers and dendrimers) may be used .

[0151] Furthermore, as the material used for the second electrode 617 formed on the EL layer 616 and functioning as a cathode, a material with a small work function (Al, Mg, Li, Ca, or their alloys and compounds, MgAg, MgIn, AlLi, etc.) is preferably used. When the light generated in the EL layer 616 passes through the second electrode 617, as the second electrode 617, a laminated structure of a thin metal thin film and a transparent conductive film (ITO, indium tin oxide containing 2 to 20 wt% of zinc oxide, silicon-containing indium tin oxide, zinc oxide (ZnO), etc.) is preferably used . By bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, the element substrate

[0152]

[0153] ​​​​​​​​​ A structure is provided in which a light-emitting element 618 is provided in a space 607 surrounded by a plate 610, a sealing substrate 604, and a sealing material 605. The space 607 is filled with a filling material. In addition to the case where an inert gas (such as nitrogen or argon) is filled, it may also be filled with a resin or the sealing material 605. Forming a recess in the sealing substrate and providing a drying material therein can suppress deterioration due to the influence of moisture, which is a preferable configuration.

[0154] It is preferable to use an epoxy-based resin or glass frit for the sealing material 605. Moreover, it is desirable that these materials are materials that do not permeate moisture and oxygen as much as possible. In addition to a glass substrate or a quartz substrate, as materials used for the sealing substrate 604, plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, or acrylic can be used.

[0155] The light-emitting device according to one aspect of the present invention can be a light-emitting device with reduced power consumption. Also, it can be an inexpensive light-emitting device.

[0156] FIG. 3 shows an example of a full-color light-emitting device formed by forming a light-emitting element that exhibits white light emission and providing a coloring layer (color filter) or the like. FIG. 3(A) shows a substrate 1001, an underlying insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a drive circuit portion 1041, first electrodes 1024W, 1024R, 1024G, 1024B of the light-emitting element, a partition wall 1025, an EL layer 1028, a second electrode 1029 of the light-emitting element, and a sealing substrate 10 31. A sealing material 1032 etc. is illustrated.

[0157] Also, in Fig. 3(A), the coloring layers (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) are provided on a transparent substrate 1033. Also, a black layer (black ma trix) 1035 may be further provided. The transparent substrate 1033 provided with the coloring layer and the black layer is aligned and fixed to the substrate 1001. Note that the coloring layer and the black layer are covered with an overcoat layer 1036. Also, in Fig. 3(A), there are a light-emitting layer where light does not pass through the coloring layer and goes outside, and a light-emitting layer where light passes through the coloring layers of each color and goes outside. Since the light that does not pass through the coloring layer is white, and the light that passes through the coloring layer is red, blue, and green, an image can be expressed with 4-color pixels.

[0158] In Fig. 3(B), an example is shown in which the coloring layers (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. As described above, the coloring layer may be provided between the substrate 1001 and the sealing substrate 1031.

[0159] Also, in the light-emitting device described above, a light-emitting device having a structure (bottom emission type) that extracts light on the substrate 1001 side where the FET is formed is used. However, a light-emitting device having a structure (top emission type) that extracts light on the sealing substrate 1031 side may also be used. A cross-sectional view of the top emission type light-emitting device is shown in Fig. 4. In this case, the substrate 1001 can use a substrate that does not transmit light. Until a connection electrode connecting the FET and the anode of the light-emitting element is fabricated, it is formed in the same manner as the bottom emission type light-emitting device. After that, the third interlayer insulating film 1037 is electrically ​ It is formed to cover the electrode 1022. This insulating film may serve as a planarization layer. The third layer The interlayer insulating film 1037 can be formed using various materials in addition to the same material as the second interlayer insulating film.

[0160] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting element are anodes here, but they can also be cathodes. Further, in the case of a top-emission type light-emitting device as shown in FIG. 4, it is preferable that the first electrode is a reflective electrode. The configuration of the EL layer 1028 is the same as the configuration described for the EL layer 103 in FIG. 1, and an element structure is adopted such that white light emission can be obtained.

[0161] In the top-emission structure as shown in FIG. 4, sealing can be performed with a sealing substrate 1031 provided with color filter layers (red color filter layer 1034R, green color filter layer 1034G, blue color filter layer 1034B). A black layer (black matrix) 1035 may be provided on the sealing substrate 1031 so as to be located between pixels. The color filter layers (red color filter layer 1034R, green color filter layer 1034G, blue color filter layer 1034B) and the black layer (black matrix) 1035 may be covered with an overcoat layer. Note that a translucent substrate is used for the sealing substrate 1031.

[0162] Here, an example of full-color display using four colors of red, green, blue, and white is shown, but it is not particularly limited, and full-color display may be performed using three colors of red, green, and blue.

[0163] Since the light-emitting device in this embodiment uses the light-emitting element described in FIG. 1(A) or (B), a light-emitting device having good characteristics can be obtained. Specifically, as shown in FIG. 1(A), ​​​​​​​​​ Alternatively, the light-emitting element described in (B) is a light-emitting element with good luminous efficiency, and has a reduced power consumption and can be used as a light-emitting device. Also, the light-emitting element described in FIG. 1(A) or (B) is relatively easy to mass-produce, and can provide an inexpensive light-emitting device.

[0164] So far, the active matrix type light-emitting device has been described. From below, a passive matrix type light-emitting device will be described. FIG. 5 shows a passive matrix type light-emitting device fabricated by applying an aspect of the present invention. Note that FIG. 5(A) is a perspective view showing the light-emitting device, and FIG. 5(B) is a cross-sectional view obtained by cutting FIG. 5(A) along the X-Y plane. In FIG. 5, an EL layer 955 is provided between an electrode 952 and an electrode 956 on a substrate 95 1. The end of the electrode 95 2 is covered with an insulating layer 953. Then, a partition layer 954 is provided on the insulating layer 953 . The side walls of the partition layer 954 have an inclination such that the distance between one side wall and the other side wall becomes narrower as it approaches the substrate surface. That is, the cross-section of the partition layer 954 in the short side direction is trapezoidal, and the bottom side (the side facing the same direction as the surface direction of the insulating layer 953 and in contact with the insulating layer 953) is shorter than the upper side (the side facing the same direction as the surface direction of the insulating layer 953 and not in contact with the insulating layer 953). By providing the partition layer 954 in this way, it is possible to prevent defects in the light-emitting element caused by static electricity or the like. Also, in the passive matrix type light-emitting device as well , a light-emitting element with good luminous efficiency shown in FIG. 1(A) or (B) is used, and a light-emitting device with reduced power consumption can be obtained. Also, the light-emitting element is a light-emitting element that is easy to mass-produce and can provide an inexpensive light-emitting device.

[0165] As described above, the light-emitting device can control a large number of minute light-emitting elements arranged in a matrix, and thus is suitably used as a display device for displaying an image.

[0166] (Lighting device) An example of using the light-emitting element described in FIG. 1(A) or FIG. 1(B) as a lighting device will be described with reference to FIG. 6. FIG. 6(B) is a top view of the lighting device, and FIG. 6(A) is a cross-sectional view taken along the line e-f in FIG. 6(B).

[0167] In the lighting device according to the present embodiment, a first electrode 401 is formed on a light-transmissive substrate 400 serving as a support. The first electrode 401 corresponds to the first electrode 101 in FIG. 1(A). When light is extracted from the side of the first electrode 401, the first electrode 401 is formed of a material having light-transmissivity.

[0168] A pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400.

[0169] An EL layer 403 is formed on the first electrode 401. The EL layer 403 corresponds to the configuration of the EL layer 103 in FIG. 1(A), or the configuration in which the first light-emitting unit 511, the second light-emitting unit 512, and the charge generation layer 513 in FIG. 1(B) are combined. For these configurations, refer to the description.

[0170] The second electrode 404 is formed to cover the EL layer 403. The second electrode 404 corresponds to the second electrode 102 in FIG. 1(A). When light is extracted from the side of the first electrode 401, the second electrode 404 is formed of a material having a high reflectance. The second electrode 404 is connected to the pad 412. By connecting thereto, voltage is supplied.

[0171] As described above, the lighting device according to one aspect of the present invention includes the light-emitting element having the first electrode 401, the EL layer 403, and the second electrode 404.

[0172] The light-emitting element having the above configuration is fixed to the sealing substrate 407 using the sealing materials 405 and 406, and the lighting device is completed by sealing. Either of the sealing materials 405 and 406 may be used. Further, a desiccant can be mixed into the inner sealing material 406 (not shown in FIG. 6(B)), and thereby, moisture can be adsorbed, leading to an improvement in reliability.

[0173] Also, by extending a part of the pad 412 and the first electrode 401 outside the sealing materials 405 and 406, it can be used as an external input terminal. Further, an IC chip 420 or the like on which a converter or the like is mounted may be provided thereon.

[0174] As described above, since the lighting device described in the present embodiment has the light-emitting element described in FIG. 1(A) or FIG. 1(B), it can be a lighting device with low power consumption. Also, it can be a lighting device with a low driving voltage. Also, it can be an inexpensive lighting device.

[0175] (Electronic device) Next, an example of an electronic device including the light-emitting element described in FIG. 1(A) or (B) in a part thereof will be described. The light-emitting element described in FIG. 1(A) or (B) has good luminous efficiency and reduced power consumption. As a result, the electronic device described in the present embodiment can be an electronic device having a light-emitting portion with reduced power consumption. Also, FIG. 1(A) or (B) ​​ Since the light-emitting element described in has a small number of film-forming layers, it is possible to make an inexpensive electronic device. It is possible.

[0176] Examples of electronic devices to which the above light-emitting element is applied include, for example, a television device (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device ), a portable game machine, a portable information terminal, an audio reproduction device, a large game machine such as a pachinko machine, etc. ) are mentioned. Specific examples of these electronic devices are shown below. Examples are as follows.

[0177] FIG. 7(A) shows an example of a television device. The television device has a display unit 7103 incorporated in a housing 710 1. Here, a configuration in which the housing 7101 is supported by a stand 7105 is shown. The display unit 7103 can display an image, and the display unit 7103 is configured by arranging the light-emitting elements described in FIG. 1(A) or (B) in a matrix. It is possible, and the display unit 7103 is configured by arranging the light-emitting elements described in FIG. 1(A) or (B) in a matrix. It is arranged.

[0178] The operation of the television device can be performed by an operation switch provided in the housing 7101 or a separate remote control operation device 7110. The operation keys 7109 provided in the remote control operation device 7110 can be used to operate the channel and volume, and the image displayed on the display unit 7103 can be operated. In addition, the remote control operation device 7110 may be configured to include a display unit 7107 for displaying information output from the remote control operation device 7110. It is provided.

[0179] In addition, the television device has a configuration including a receiver, a modem, etc. The receiver is used for general It is possible to receive television broadcasts, and furthermore, communicate wired or wirelessly via a modem By connecting to a network, it is also possible to perform one-way (sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0180] Figure 7(B1) is a computer, including a main body 7201, a housing 7202, a display unit 7203, a ke yboard 7204, an external connection port 7205, a pointing device 7206, etc. Note that this computer is manufactured by arranging light-emitting elements similar to those described in Fig. 1(A) or (B) in a matrix and using them for the display unit 7203. The computer in Fig. 7(B1) may also be in the form shown in Fig. 7(B2). The computer in Fig. 7(B2) has a second display unit 7 210 provided instead of the keyboard 7204 and the pointing device 7206. The second display unit 7210 is a touch panel type, and by operating the input display shown on the second display unit 7210 with a finger or a dedicated pen, input can be performed. Also, the second display unit 7210 can display not only input displays but also other images. The display unit 7203 may also be a touch panel. By connecting the two screens with a hinge, it is possible to prevent troubles such as damaging or breaking the screens during storage or transportation. Note that this computer is manufactured by arranging the light-emitting elements described in Fig. 1(A) or (B) in a matrix and using them for the display unit 7203.

[0181] Figure 7(C) is a portable gaming machine, composed of two housings, a housing 7301 and a housing 7302 and are connected so as to be openable and closable by a connecting portion 7303. The housing 7301 incorporates a display portion 7304 manufactured by arranging the light-emitting elements described in FIG. 1( (A) or (B) in a matrix, and the housing 7302 incorporates a display portion 7305. Further, the portable game machine shown in FIG. 7(C) also includes, among other things, a speaker portion 7306, a recording medium insertion portion 7307, an LED lamp 7308, input means (operation keys 7309, connection terminals 7310, sensors 7311 (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, gradient, vibration, odor or infrared rays), a microphone 7312), etc. Of course, the configuration of the portable game machine is not limited to the above, and at least both the display portion 7304 and the display portion 7305, or one of them, may use a display portion manufactured by arranging the light-emitting elements described in FIG. 1(A) or (B) in a matrix, and other accessory equipment may be appropriately provided. The portable game machine shown in FIG. 7(C) has a function of reading a program or data recorded on a recording medium and displaying it on the display portion, and a function of sharing information by performing wireless communication with other portable game machines. Note that the functions of the portable game machine shown in FIG. 7(C) are not limited to this, and it can have various functions.

[0182] FIG. 7(D) shows an example of a mobile phone. The mobile phone includes, in addition to a display portion 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 74 05, a microphone 7406, etc. Note that the mobile phone is as shown in FIG. 1(A) or (B) ​​​​​It has a display unit 7402 manufactured by arranging the described light-emitting elements in a matrix form.

[0183] The mobile phone shown in Fig. 7(D) can also be configured such that information can be input by touching the display unit 7402 with a finger or the like. In this case, operations such as making a call or creating an email can be performed by touching the display unit 7402 with a finger or the like. There are mainly three modes on the screen of the display unit 7402. The first is a display mode mainly for displaying images, the second is an input mode mainly for inputting information such as characters, and the third is a display + input mode in which the two modes of the display mode and the input mode are mixed. For example, when making a call or creating an email, the display unit 7402 may be set to the character input mode mainly for character input, and an input operation on the characters displayed on the screen may be performed. In this case, it is preferable to display a keyboard or number buttons on most of the screen of the display unit 7402.

[0184] Moreover, by providing a detection device having sensors such as a gyro and an acceleration sensor inside the mobile phone to detect the inclination, the orientation (vertical or horizontal) of the mobile phone can be determined, and the screen display of the display unit 7402 can be automatically switched. In addition, the switching of the screen mode is performed by touching the display unit 7402 or operating the operation button 7403 of the housing 7401. It can also be switched according to the type of image displayed on the display unit 7402. For example, when the image signal displayed on the display unit is a moving image

[0185]

[0186]

[0187] Switch to the display mode if it is data, or to the input mode if it is text data.

[0188] Also, in the input mode, detect the signal detected by the optical sensor of the display unit 7402, and if there is no input by the touch operation of the display unit 7402 for a certain period, the screen mode may be controlled to switch from the input mode to the display mode.

[0189] The display unit 7402 can also function as an image sensor. For example, by touching the display unit 74 02 with a palm or finger and imaging palm prints, fingerprints, etc., personal authentication can be performed. Also, by using a backlight that emits near-infrared light or a sensing light source that emits near-infrared light in the display unit, finger vein, palm vein, etc. can also be imaged.

[0190] As described above, the application range of the light-emitting device including the light-emitting element described in FIG. 1(A) or (B) is extremely wide, and this light-emitting device can be applied to electronic devices in all fields. By using the light-emitting element described in FIG. 1(A ) or (B), an electronic device with reduced power consumption can be obtained.

[0191] FIG. 8 shows an example of a liquid crystal display device in which the light-emitting element described in FIG. 1(A) or (B) is applied to a backlight. The liquid crystal display device shown in FIG. 8 includes a housing 901, a liquid crystal layer 902, a backlight unit 903, and a housing 904. The liquid crystal layer 902 is connected to a driver IC 905. Also, the light-emitting element described in FIG. 1(A) or (B) is used in the backlight unit 903, and current is supplied through a terminal 906.

[0192] The light-emitting element described in FIG. 1(A) or (B) is applied to the backlight of the liquid crystal display device. This enables a backlight with reduced power consumption. Also, by using the light-emitting element described in Fig. 1(A) or (B), a surface-emitting lighting device can be fabricated, and it is also possible to increase the area to a large size. This makes it possible to increase the area of the backlight and also increase the area of the liquid crystal display device. Furthermore, the light-emitting device applying the light-emitting element described in Fig. 1(A) or (B) can have a smaller thickness compared to the conventional one, so that the display device can also be made thinner. Fig. 9 shows an example in which the light-emitting element described in Fig. 1(A) or (B) is used in an electric stand which is a lighting device. The electric stand shown in Fig. 9 has a housing 2001 and a light source 2002, and the light-emitting element described in Fig. 1(A) or (B) is used as the light source 2002.

[0193] Fig. 10 shows an example in which the light-emitting element described in Fig. 1(A) or (B) is used as an indoor lighting device 3001. Also, since the light-emitting element described in Fig. 1(A) or (B) can have a large area, it can be used as a large-area lighting device.

[0194]

[0195] The light-emitting element described in Fig. 1(A) or (B) can also be mounted on the windshield or dashboard of an automobile. Fig. 11 shows an embodiment in which the light-emitting element described in Fig. 1(A) or (B) is used for the windshield or dashboard of an automobile. Display areas 5000 to 5005 are displays provided using the light-emitting element described in Fig. 1(A) or (B).

[0196] Display area 5000 and display area 5001 are provided on the windshield of the automobile as shown in Fig. 1(A). ) or a display device equipped with the light-emitting element described in (B). The light-emitting element described in FIG. 1(A) or (B) is manufactured by forming the first electrode and the second electrode with translucent electrodes, resulting in a so-called see-through display device where the opposite side can be seen through. In the case of a see-through display, even if it is installed on the windshield of an automobile, it can be installed without obstructing the view. When providing transistors or the like for driving, it is preferable to use organic transistors made of organic semiconductor materials or transistors using oxide semiconductors, i.e., translucent transistors.

[0197] The display area 5002 is a display device equipped with the light-emitting element described in FIG. 1(A) or (B) provided in the pillar portion. In the display area 5002, by projecting the video from the imaging means provided on the vehicle body, the view blocked by the pillar can be complemented. Similarly, the display area 5003 provided in the dashboard portion complements the view blocked by the vehicle body by projecting the video from the imaging means provided outside the vehicle, filling in the blind spot and enhancing safety. By projecting the video to complement the invisible parts, a safer confirmation can be performed more naturally without discomfort.

[0198] The display areas 5004 and 5005 can provide various other information such as navigation information, speedometers, tachometers, travel distances, fuel supply amounts, gear states, air conditioner settings, etc. The display can be appropriately changed in terms of its display items and layout according to the user's preference. Note that this information can also be provided in the display areas 5000 to 5003. In addition, the display areas 5000 to 5005 can also be used as lighting devices. It is possible.

[0199] The light-emitting element described in FIG. 1(A) or (B) can be a light-emitting element with high luminous efficiency. In addition, it can be a light-emitting element with low power consumption. From this, even if a large number of large screens are provided in the display areas 500 0 to 5005, the load on the battery is small and it can be used comfortably. Therefore, the light-emitting element described in FIG. 1(A) or (B) The light-emitting device or lighting device using the same can be preferably used as a vehicle-mounted light-emitting device or lighting device. It can be used. It can be used.

[0200] FIGS. 12(A) and 12(B) are an example of a two-foldable tablet terminal. FIG. 1 2(A) shows an open state. The tablet terminal includes a housing 9630, a display unit 9631a , a display unit 9631b, a display mode switching switch 9034, a power switch 9035, a power saving mode switching switch 9036, a fastener 9033, and an operation switch 9038. Note that the tablet terminal is manufactured by using a light-emitting device including the light-emitting element described in FIG. 1(A) or (B) for one or both of the display units 9631a and 9631b. It is made.

[0201] A part of the display unit 9631a can be a touch panel area 9632a, and data can be input by touching the displayed operation keys 9637. Note that in the display unit 963 1a, as an example, a configuration in which half of the area has only a display function and the other half of the area has a touch panel function is shown, but the configuration is not limited to this. The display unit 963 All areas of 1a may also be configured to have the function of a touch panel. For example, the display unit 96 The entire surface of 31a can be made to display keyboard buttons to serve as a touch panel, and the display unit 9631b can be used as a display screen.

[0202] Also, in the display unit 9631b as well as in the display unit 9631a, a part of the display unit 9631b can be made into a touch panel area 9632b. Further, by touching the position where the keyboard display switching button 9639 of the touch panel is displayed with a finger or a stylus, etc., keyboard buttons can be displayed on the display unit 9631b.

[0203] Also, touch input can be performed simultaneously on the touch panel area 9632a and the touch panel area 9632b.

[0204] Also, the display mode switching switch 9034 can switch the display orientation such as portrait or landscape, and can select switching between monochrome display and color display, etc. The power saving mode switching switch 9036 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet type terminal during use. The tablet type terminal may incorporate other detection devices such as not only an optical sensor but also sensors for detecting inclination such as a gyro and an acceleration sensor.

[0205] Also, in Fig. 12(A), an example where the display areas of the display unit 9631b and the display unit 9631a are the same is shown, but it is not particularly limited, and the size of one may be different from that of the other, and the display quality may also be different. For example, one may be a display panel that can perform higher definition display than the other.

[0206] ​​ Figure 12(B) is in a closed state. In the tablet terminal of the present embodiment, the housing 9630, solar cell 9633, charge / discharge control circuit 9634, battery 9635, DCD C converter 9636 are provided. Note that in Figure 12(B), the charge / discharge control circuit 963 4 is shown as an example having a configuration including battery 9635 and DCDC converter 9636. is shown.

[0207] Since the tablet terminal is foldable in two, the housing 9630 can be closed when not in use. Therefore, the display units 9631a and 9631b can be protected, and a tablet terminal with excellent durability and reliability from the perspective of long-term use can be provided. In addition, the tablet terminals shown in FIGS. 12(A) and 12(B) can also have functions such as displaying various

[0208] information (still images, moving images, text images, etc.), a calendar, a date or time, etc. on the display unit, a touch input function for touching and inputting or editing the information displayed on the display unit, a function of controlling processing by various software (programs), and the like. can be performed.

[0209]

[0209] The solar cell 9633 mounted on the surface of the tablet terminal can supply power to the touch panel , display unit, or video signal processing unit, etc. Note that the solar cell 9633 is preferably provided on one or two sides of the housing 9630 so that efficient charging of the battery 9635 can be performed.

[0210] In addition, regarding the configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 12(B), refer to FIG. 12( C) is shown in a block diagram and described. Figure 12(C) shows a solar cell 9633, a battery 9 635, a DCDC converter 9636, a converter 9638, and switches SW1 to SW3 , and a display unit 9631 are shown. The battery 9635, the DCDC converter 963 6, the converter 9638, and the switches SW1 to SW3 correspond to the locations of the charge / discharge control circuit 9634 shown in Figure 12(B).

[0211] First, an example of the operation when power is generated by the solar cell 9633 due to external light will be described . The power generated by the solar cell becomes a voltage for charging the battery 9635, and is stepped up or down by a DC DC converter 9636. When the power charged by the solar cell 9633 is used for the operation of the display unit 9631, switch SW1 is turned on, and the converter 9638 steps up or down the voltage to the voltage required for the display unit 9631. Also , when the display on the display unit 9631 is not performed, SW1 is turned off, SW2 is turned on, and the battery 9635 may be configured to be charged. Note that the solar cell 9633 is shown as an example of a power generation means, but the power generation means is not particularly

[0212] limited, and other power generation means such as a piezoelectric element (piezo element) or a thermoelectric conversion element (Peltier element) may be used to charge the battery 9635. A contactless power transmission module that wirelessly (non-contact) transmits and receives power for charging, or a configuration that combines other charging means may be used, and it is not necessary to have a power generation means.

[0213]

[0213] Also, if the above display unit 9631 is provided, it is not limited to the tablet-type terminal having the shape shown in Figure 12.

Example

[0214] In this example, the manufacturing methods and characteristics of light-emitting elements 1 to 3, which are light-emitting elements of one aspect of the present invention, and light-emitting element 4, which is a reference example, are shown. The structural formulas of the organic compounds used in light-emitting elements 1 to 4 are shown below. In this example, the manufacturing methods and characteristics of light-emitting elements 1 to 3, which are light-emitting elements of one aspect of the present invention, and light-emitting element 4, which is a reference example, are shown. The structural formulas of the organic compounds used in light-emitting elements 1 to 4 are shown below. In this example, the manufacturing methods and characteristics of light-emitting elements 1 to 3, which are light-emitting elements of one aspect of the present invention, and light-emitting element 4, which is a reference example, are shown. The structural formulas of the organic compounds used in light-emitting elements 1 to 4 are shown below.

[0215]

Chemical formula

[0216] (Manufacturing method of light-emitting element 1) On a glass substrate, indium tin oxide (ITSO) containing silicon oxide was formed by sputtering to form a first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as the anode of the light-emitting element. On a glass substrate, indium tin oxide (ITSO) containing silicon oxide was formed by sputtering to form a first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as the anode of the light-emitting element. On a glass substrate, indium tin oxide (ITSO) containing silicon oxide was formed by sputtering to form a first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as the anode of the light-emitting element. On a glass substrate, indium tin oxide (ITSO) containing silicon oxide was formed by sputtering to form a first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as the anode of the light-emitting element.

[0217] Next, as a pretreatment for forming a light-emitting element on the substrate, the substrate surface was washed with water, baked at 200 °C for 1 hour, and then subjected to UV ozone treatment for 370 seconds. Next, as a pretreatment for forming a light-emitting element on the substrate, the substrate surface was washed with water, baked at 200 °C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0218] After that, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to about 10 -4 Pa, and vacuum baking was performed at 170 °C for 30 minutes in the heating chamber of the vacuum evaporation apparatus. Then, the substrate was allowed to cool for about 30 minutes. After that, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to about 10 Pa, and vacuum baking was performed at 170 °C for 30 minutes in the heating chamber of the vacuum evaporation apparatus. Then, the substrate was allowed to cool for about 30 minutes.

[0219] Next, with the surface on which the first electrode 101 is formed facing downward, the substrate on which the first electrode 101 is formed was fixed to a substrate holder provided in the vacuum evaporation apparatus, and the pressure was reduced to about 10 Pa. Then, on the first electrode 101, by vapor deposition using resistance heating, the above structural formula (i) was represented -4 Pa, and then Pa, and then 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzothiophene ne) (abbreviation: DBT3P-II), and molybdenum(VI) oxide are co-evaporated to form a hole injection layer 111. The film thickness is 40 nm, and the ratio of DBT3P-II to molybdenum oxide is adjusted to 4:2 (= DBT3P-II: molybdenum oxide) by weight ratio . Note that the co-evaporation method is a deposition method in which deposition is performed simultaneously from a plurality of evaporation sources in one processing chamber .

[0220] Subsequently, 3-[4-(9-phenanthryl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn) represented by the above structural formula (ii) is formed into a film on the hole injection layer 111 so as to have a film thickness of 20 nm to form a hole transport layer 112 .

[0221] Furthermore, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenz[c,g]carbazole (abbreviation: cgDBCzPA) represented by the above structural formula (iii) and N,N’-bis(3-methylphenyl l)-N,N’-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl] -pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn) are co-evaporated in a weight ratio of 1: 0.03 (= cgDBCzPA: 1,6mMemFLPAPrn) to form a first light-emitting layer 113a which is a fluorescent light-emitting layer. Next, 2-[3’-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo zo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (v), and the above structural formula (vi ​​​​) N-(1,1'-Biphenyl-4-yl)-N-[4-(9-phenyl-9 H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2- amine (abbreviation: PCBBiF) were co-evaporated at a weight ratio of 0.6:0.4 (= 2mDBTBPDBq-I I:PCBBiF) to form the separation layer 113b. The film thickness of the separation layer 113b was set to 2 nm. Then, 2mDBTBPDBq-II, PCBBiF, and the above bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl )-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC }(2,4-pentanedionato-κ 2 O,O’)iridium(III) (abbreviation: [Ir( dmdppr-dmp)2(acac)]) were co-evaporated in a weight ratio of 0.2:0.8:0.05 (= 2mDBTBPDBq-II:PCBBiF:[Ir(dmdppr-dmp)2(ac ac)]) by 5 nm to form the first phosphorescent light-emitting layer 113c-1, and then 2mDBTBPDBq-II, PCBBiF, and the bis represented by the above structural formula (viii) [2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl-κC](2, 4-pentanedionato-κ 2 O,O’)iridium(III) (abbreviation: [Ir(tBup pm)2(acac)]) were co-evaporated in a weight ratio of 0.7:0.3:0.05 (= 2mDBTBPD Bq-II:PCBBiF:[Ir(tBuppm)2(acac)]) by 2 0 nm to form the second phosphorescent light-emitting layer 113c-2, and the second light-emitting layer 113c which is a phosphorescent light-emitting layer was formed. Above, in the light-emitting element 1, the first light-emitting layer 113a and the second light-emitting layer 113c form the light-emitting layer 113.

[0222] In the phosphorescent light-emitting layer (the second light-emitting layer 113c), 2mDBTBPDBq-II and PCBBiF form an exciplex. Further, the emission wavelength thereof is the longest wavelength side absorption band of [Ir(dmdppr -dmp)2(acac)] and [Ir(tBuppm)2(acac)], and the configuration has high energy transfer efficiency.

[0223] Furthermore, the singlet excitation energy of cgDBCzPA, which is the host material of the fluorescent light-emitting layer (the first light-emitting layer 113a), is larger than the singlet excitation energy of 1,6mMemFLPAPrn, which is the fluorescent light-emitting substance, and the triplet excitation energy of cgDBCzPA is smaller than the triplet excitation energy of 1,6 mMemFLPAPrn. The fluorescent light-emitting layer (the first light-emitting layer 113a) has a configuration in which regeneration and emission of singlet excitons due to triplet-triplet annihilation are easily obtained.

[0224] Thereafter, 2mDBTBPDBq-II is formed into a film with a thickness of 10 nm on the phosphorescent light-emitting layer (the second light-emitting layer 113c), and further, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (ix) is formed into a film with a thickness of 15 nm to form the electron transport layer 114.

[0225] After forming the electron transport layer 114, then, lithium fluoride (LiF) is deposited to a film thickness of 1 nm to form the electron injection layer 115, and finally, as the second electrode 1 02 that functions as a cathode, aluminum is deposited to a film thickness of 200 nm, whereby the light-emitting device 1 of this example is manufactured.

[0226] ​​​​​​​​In addition, in the above-described vapor deposition process, all vapor depositions were performed using the resistance heating method.

[0227] (Method for manufacturing light-emitting elements 2 and 3) Light-emitting elements 2 and 3 are elements manufactured by changing the film thicknesses of the separation layers 113b in light-emitting element 1 to 5n m and 10 nm, respectively.

[0228] (Method for manufacturing light-emitting element 4) Light-emitting element 4 is a light-emitting element having a structure obtained by removing the separation layer 113b from the structure of light-emitting element 1 .

[0229] After performing the operation of sealing light-emitting elements 1 to 4 with a glass substrate so that the light-emitting elements are not exposed to the air in a glove box under a nitrogen atmosphere (applying a sealing material around the elements, performing UV treatment and heat treatment at 80 °C for 1 hour during sealing), the reliability of these light-emitting elements was measured. The measurement was performed at room temperature (an atmosphere maintained at 25 °C). The element structures of light-emitting elements 1 to 4 are summarized in the following table.

[0230] The current density-luminance characteristics of light-emitting elements 1 to 4 are shown in FIG. 13, the luminance-current efficiency characteristics are shown in FIG.

[0231]

Table 1

[0232] 14, the voltage-luminance characteristics are shown in FIG. 15, the luminance-external quantum efficiency characteristics are shown in FIG. 16, and the emission spectrum is shown in FIG. 17. As described above, light-emitting elements 1 to 4 have a structure without an intermediate layer, but have good emission with a current efficiency of about 40 cd / A or more and an external quantum efficiency of about 18% or more at around 100

[0233] 0 cd / m 0 cd / m 2 and above. It was found to exhibit luminous efficiency. Also, the driving voltage near 1000 cd / m 2 is also as low as in the 3 V range, and it can be seen that it is very low compared to the tandem type light-emitting element. Furthermore, Light-emitting elements 1 to Light-emitting element 3 have an external quantum efficiency of 19% or more near 1000 cd / m and exhibit very good efficiency. It can be seen that the main characteristics 2 near 1000 cd / m of Light-emitting elements 1 to 4 are shown in a table summarizing the values. 2

[0234]

Table 2

[0235] Also, in the emission spectrum of Fig. 17, red emission derived from [Ir(dmdppr-dmp)2(acac) , green emission derived from [Ir(tBuppm)2(acac)] and blue emission derived from 1, 6mMemFLPAPrn were both observed. From this, it was found that sufficient emission was obtained from both the first light-emitting layer 113a which is a fluorescent light-emitting layer and the second light-emitting layer 113c which is a phosphorescent light-emitting layer.

[0236] Thus, it was found that Light-emitting elements 1 to 4 are light-emitting elements that can be manufactured simply and inexpensively while having very well-balanced good characteristics. This result is due to the fact that exciton diffusion is suppressed and the non-radiative deactivation of triplet excitons is reduced by using an exciplex as the energy donor of the phosphorescent light-emitting layer, and the generation of delayed fluorescence due to triplet-triplet annihilation in the host material of the fluorescent light-emitting layer contributes to the improvement of the luminous efficiency. Also, Light-emitting elements 1 to 3 use the separation layer 113b ​​​​​​​From the phosphorescent light-emitting layer (second light-emitting layer 113c) to the fluorescent light-emitting layer (first light-emitting layer 113a) Energy transfer at the interface to was also suppressed, and it was found that better characteristics were exhibited.

Example

[0237] In this example, the manufacturing method and characteristics of the light-emitting element 5, which is a light-emitting element of one aspect of the present invention, are shown. The structural formula of the organic compound used in the light-emitting element 5 is shown below.

[0238]

Chemical formula

[0239] (Manufacturing method of the light-emitting element 5) Indium tin oxide (ITSO) containing silicon oxide was formed on a glass substrate by sputtering to form the first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as the anode of the light-emitting element.

[0240] Next, as a pretreatment for forming the light-emitting element on the substrate, the substrate surface was washed with water, baked at 200 °C for 1 hour, and then UV ozone treatment was performed for 370 seconds.

[0241] After that, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to about 10 -4 Pa, and vacuum baking was performed at 170 °C for 30 minutes in the heating chamber of the vacuum evaporation apparatus. Then, the substrate was allowed to cool for about 30 minutes.

[0242] Next, with the surface on which the first electrode 101 is formed facing downward, the substrate on which the first electrode 101 is formed was fixed to the substrate holder provided in the vacuum evaporation apparatus, and the pressure was reduced to about 10 -4 Pa ​​After pressing, by vapor deposition using resistance heating, on the first electrode 101, the 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzothiophene) represented by the above structural formula (i) (abbreviation: DBT3P-II), and molybdenum(VI) oxide are co-evaporated to form a hole injection layer 111. The film thickness is 40 nm, and the ratio of DBT3P-II to molybdenum oxide is adjusted to be 4:2 ( = DBT3P-II: molybdenum oxide) by weight. Note that the co-evaporation method is a vapor deposition method in which vapor deposition is performed simultaneously from a plurality of evaporation sources in one processing chamber.

[0243] Subsequently, on the hole injection layer 111, 3-[4-(9-phenanthryl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn) represented by the above structural formula (ii) is formed into a film to a thickness of 10 nm to form a hole transport layer 112.

[0244] Further, on the hole transport layer 112, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and N,N’-bis(3-methylphenyl)-N,N’-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl] -pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn) represented by the above structural formula (iv) are co-evaporated in a weight ratio of 1: 0.04 (= cgDBCzPA: 1,6mMemFLPAPrn) to a thickness of 5 nm to form a first light-emitting layer 113a which is a fluorescent light-emitting layer. Next, 2-[3’-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzothiophene represented by the above structural formula (v) Z[f,h] quinoxaline (abbreviation: 2mDBTBPDBq-II), and N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9 ) phenyl]-9,9-dimethyl-9H-fluorene-2- amine (abbreviation: PCBBiF) represented by the above structural formula (vi were co-evaporated at a weight ratio of 0.6:0.4 (= 2mDBTBPDBq-I I:PCBBiF) to form the separation layer 113b. The film thickness of the separation layer 113b was set to 2 nm. Then, 2mDBTBPDBq-II, PCBBiF, and the above bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl enyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC }(2,4-pentanedionato-κ 2 O,O’)iridium(III) (abbreviation: [Ir( dmdppr-dmp)2(acac)]) were co-evaporated at a weight ratio of 0.5:0.5:0.05 (= 2mDBTBPDBq-II:PCBBiF:[Ir(dmdppr-dmp)2(ac ac)]) by 5 nm to form the first phosphorescent emission layer 113c-1, and then subsequently, 2mDBTBPDBq-II, PCBBiF, and bis[2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl-κC](2, 4-pentanedionato-κ O,O’)iridium(III) (abbreviation: [Ir(tBup 2 pm)2(acac)]) represented by the above structural formula (viii) were co-evaporated at a weight ratio of 0.7:0.3:0.05 (= 2mDBTBPD Bq-II:PCBBiF:[Ir(tBuppm)2(acac)]) by 2 0 nm to form the second phosphorescent emission layer 113c-2, and the second emission layer 113c which is a phosphorescent emission layer was formed. ​

[0245] In the phosphorescent light-emitting layer (second light-emitting layer 113c), 2mDBTBPDBq-II and PCBBiF form an exciplex. Further, the emission wavelength thereof is overlapped with the absorption band on the longest wavelength side of [Ir(dmdppr -dmp)2(acac)] and [Ir(tBuppm)2(acac)], and has a configuration with high energy transfer efficiency.

[0246] Furthermore, the singlet excitation energy of cgDBCzPA, which is the host material of the fluorescent light-emitting layer (first light-emitting layer 113a), is larger than the singlet excitation energy of 1,6mMemFLPAPrn, which is the fluorescent light-emitting substance, and the triplet excitation energy of cgDBCzPA is smaller than the triplet excitation energy of 1,6mMemFLPAPrn. The fluorescent light-emitting layer (first light-emitting layer 113a) has a configuration in which regeneration and emission of singlet excitons due to triplet-triplet annihilation are easily obtained. After that, 2mDBTBPDBq-II is formed into a film with a film thickness of 10 nm on the phosphorescent light-emitting layer (second light-emitting layer 113c), and further, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (ix) is formed into a film with a film thickness of 15 nm to form the electron transport layer 114.

[0247] After forming the electron transport layer 114, then, lithium fluoride (LiF) is vapor-deposited to have a film thickness of 1 nm to form the electron injection layer 115, and finally, as the second electrode 1 02 that functions as a cathode, aluminum is vapor-deposited to have a film thickness of 200 nm, thereby fabricating the light-emitting device 5 of this example.

[0248] After forming the electron transport layer 114, then, lithium fluoride (LiF) is vapor-deposited to have a film thickness of 1 nm to form the electron injection layer 115, and finally, as the second electrode 1 02 that functions as a cathode, aluminum is vapor-deposited to have a film thickness of 200 nm to fabricate the light-emitting device 5 of this example.

[0249] ​​​​In the above-described vapor deposition process, all vapor depositions were carried out using the resistance heating method.

[0250] The light-emitting element 5 was sealed with a glass substrate in a glove box under a nitrogen atmosphere so that the light-emitting element was not exposed to the atmosphere. (A sealing material was applied around the element, and UV treatment was performed during sealing, followed by heat treatment at 80°C for 1 hour). After that, the reliability of these light-emitting elements was measured. The measurement was performed at room temperature (an atmosphere maintained at 25°C).

[0251] The element structure of the light-emitting element 5 was summarized in the following table.

[0252]

Table 3

[0253] The current density-luminance characteristics of the light-emitting element 5 are shown in FIG. 18, the luminance-current efficiency characteristics are shown in FIG. 19, the voltage-luminance characteristics are shown in FIG. 20, the luminance-external quantum efficiency characteristics are shown in FIG. 21, the emission spectrum is shown in FIG. 22, and the luminance-CIE chromaticity characteristics are shown in FIG. 23.

[0254] As described above, although the light-emitting element 5 has a structure without an intermediate layer, it shows good luminous efficiency with a current efficiency of about 40 cd / A or more and an external quantum efficiency of about 18% or more at around 1000 cd / m². 2 attached It was also found that the driving voltage is as low as around 3 V, which is very low compared to tandem-type light-emitting elements. A table summarizing the main characteristic values of the light-emitting element 5 around 1000 cd / m² is shown. 2 near

[0255]

Table 4

[0256] ​​​In addition, in the emission spectrum of FIG. 22, the red emission from [[Ir(dmdppr-dmp)2(acac)]] , the green emission from [[Ir(tBuppm)2(acac)]] and the blue emission from 1,6 mMemFLPAPrn were both observed. From this, it was found that sufficient emission was obtained from both the first emission layer 113a which is a fluorescent emission layer and the second emission layer 113c which is a phosphorescent emission layer.

[0257] In addition, from the luminance-CIE chromaticity characteristics of FIG. 23, it was found that the light-emitting device 5 is a light-emitting device with a very small color change in the practical luminance region. Note that the color change observed around 100 cd / m 2 is due to the difference in the emission start voltage between phosphorescence and fluorescence. Since the phosphorescent layer has a lower emission start voltage than the fluorescent layer, only phosphorescence is observed in the low luminance region, and fluorescence also starts to emit around 100 cd / m , resulting in a color change around 100 cd / m . In the practical luminance region where both fluorescence and phosphorescence stably emit light, the color change is very small. 2 2

[0258] Thus, it was found that the light-emitting device 5 is a light-emitting device that has very well-balanced good characteristics and can be manufactured simply and inexpensively. This result is due to the suppression of exciton diffusion by using an exciplex as the energy donor of the phosphorescent emission layer, reducing the non-radiative deactivation of triplet excitation energy, and the contribution of the improvement of the emission efficiency by the generation of delayed fluorescence accompanying the triplet-triplet annihilation in the host material of the fluorescent emission layer. In addition, the light-emitting device 5 uses the separation layer 113b, so that the phosphorescent emission layer (the second Energy at the interface from the light-emitting layer 113c) to the fluorescent light-emitting layer (the first light-emitting layer 113a) The energy transfer was also suppressed, and better characteristics were shown.

Example

[0259] In this example, the manufacturing method and characteristics of the light-emitting elements 6 and 7, which are light-emitting elements of one aspect of the present invention, are shown. The structural formulas of the organic compounds used in the light-emitting elements 6 and 7 are shown below as follows.

[0260]

Chemical formula

[0261] (Manufacturing method of the light-emitting element 6) On a glass substrate, indium tin oxide (ITSO) containing silicon oxide was deposited by sputtering to form the first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as the anode of the light-emitting element and is the anode.

[0262] Next, as a pretreatment for forming the light-emitting element on the substrate, the substrate surface was washed with water, baked at 200 °C for 1 hour, and then UV ozone treatment was performed for 370 seconds.

[0263] After that, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to about 10 -4 Pa, and vacuum baking was performed at 170 °C for 30 minutes in the heating chamber of the vacuum evaporation apparatus. Then, the substrate was allowed to cool for about 30 minutes and cooled.

[0264] Next, with the surface on which the first electrode 101 is formed facing downward, the substrate on which the first electrode 101 is formed was fixed to the substrate holder provided in the vacuum evaporation apparatus, and the pressure was reduced to about 10 -4 Pa and the pressure was reduced to about 10 After pressing, 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (i) and molybdenum(VI) oxide are co-evaporated on the first electrode 101 by a vapor deposition method using resistance heating to form a hole injection layer 111. The film thickness is 30 nm, and the ratio of DBT3P-II to molybdenum oxide is adjusted to be 2:1 (= DBT3P-II: molybdenum oxide) by weight.

[0265] Subsequently, 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA) represented by the above structural formula (x) is formed into a film with a film thickness of 20 nm on the hole injection layer 111 to form a hole transport layer 112.

[0266] On the hole transport layer 112, PCzPA and 1,6mMemFLPAPrn are co-evaporated in a weight ratio of 1:0.05 (= PCzPA: 1,6mMemFLPAPrn) by 5 nm to form a first light-emitting layer 113a which is a fluorescent light-emitting layer. Next, 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) represented by the above structural formula (xi) and 4,4’-di(N-carbazolyl)biphenyl (abbreviation: CBP) represented by the above structural formula (xii) are co-evaporated in a weight ratio of 0.4:0.6 (= 4,6mCzP2Pm: CBP) to form a separation layer 113b. The film thickness of the separation layer 113b is 2 nm. Thereafter, 2mDBTBPDBq-II, PCBBiF, and (acetylacetonato)bis(4,6-diphenylpyrimidinato) represented by the above structural formula (xiii) ​​​​​​​​​​​​​​​Iridium(III) (abbreviation: [Ir(dppm)2(acac)]) was co-evaporated at a weight ratio 0.8:0.2:0.05 (= 2mDBTBPDBq-II:PCBBiF:[Ir(d ppm)2(acac)]) to a thickness of 20 nm to form the second phosphorescent light-emitting layer 113c.

[0267] In the phosphorescent light-emitting layer (the second light-emitting layer 113c), 2mDBTBPDBq-II and PCBBiF form an exciplex. Also, its emission wavelength overlaps with the absorption band on the longest wavelength side of [Ir(dppm)2 (acac)], resulting in a configuration with high energy transfer efficiency. That is.

[0268] Furthermore, the singlet excitation energy of PCzPA, which is the host material of the fluorescent light-emitting layer (the first light-emitting layer 113a), is greater than the singlet excitation energy of 1,6mMemFLPAPrn, which is the fluorescent light-emitting substance, and the triplet excitation energy of PCzPA is smaller than the triplet excitation energy of 1,6mMemFL PAPrn. Thus, the fluorescent light-emitting layer (the first light-emitting layer 113a) has a configuration in which the regeneration and emission of singlet excitons due to triplet-triplet annihilation are easily obtained. That is, the fluorescent light-emitting layer (the first light-emitting layer 113a) has a configuration in which the regeneration and emission of singlet excitons due to triplet-triplet annihilation are easily obtained. That is, the fluorescent light-emitting layer (the first light-emitting layer 113a) has a configuration in which the regeneration and emission of singlet excitons due to triplet-triplet annihilation are easily obtained. That is, the fluorescent light-emitting layer (the first light-emitting layer 113a) has a configuration in which the regeneration and emission of singlet excitons due to triplet-triplet annihilation are easily obtained.

[0269] Thereafter, 2mDBTBPDBq-II was formed into a film with a thickness of 10 nm on the phosphorescent light-emitting layer (the second light-emitting layer 113c), and further, BPhen was formed into a film with a thickness of 15 nm to form the electron transport layer 114. After forming the electron transport layer 114, lithium fluoride (LiF) was then evaporated to a thickness of 1 nm to form the electron injection layer 115, and finally, the second electrode 1 that functions as the cathode

[0270] After forming the electron transport layer 114, lithium fluoride (LiF) was then evaporated to a thickness of 1 nm to form the electron injection layer 115, and finally, the second electrode 1 that functions as the cathode After forming the electron transport layer 114, lithium fluoride (LiF) was then evaporated to a thickness of 1 nm to form the electron injection layer 115, and finally, the second electrode 1 that functions as the cathode As 02, aluminum was deposited to a film thickness of 200 nm, and the light-emitting element 6 of this example was fabricated. was fabricated.

[0271] In addition, in the above-described deposition process, all depositions were performed using the resistance heating method.

[0272] (Fabrication method of light-emitting element 7) The light-emitting element 7 was formed by using 4,6mCzP2Pm alone for the separation layer 113b in the light-emitting element 6. The others were formed in the same manner as the light-emitting element 6.

[0273] The light-emitting elements 6 and 7 were sealed with a glass substrate in a glove box under a nitrogen atmosphere so that the light-emitting elements were not exposed to the air (a sealing material was applied around the elements, and UV treatment and heat treatment were performed at 80 °C for 1 hour during sealing). After that, the reliability of these light-emitting elements was measured. The measurement was performed at room temperature (an atmosphere maintained at 25 °C). The light-emitting elements 6 and 7 were sealed with a glass substrate in a glove box under a nitrogen atmosphere so that the light-emitting elements were not exposed to the air (a sealing material was applied around the elements, and UV treatment and heat treatment were performed at 80 °C for 1 hour during sealing). After that, the reliability of these light-emitting elements was measured. The measurement was performed at room temperature (an atmosphere maintained at 25 °C). The light-emitting elements 6 and 7 were sealed with a glass substrate in a glove box under a nitrogen atmosphere so that the light-emitting elements were not exposed to the air (a sealing material was applied around the elements, and UV treatment and heat treatment were performed at 80 °C for 1 hour during sealing). After that, the reliability of these light-emitting elements was measured. The measurement was performed at room temperature (an atmosphere maintained at 25 °C). The light-emitting elements 6 and 7 were sealed with a glass substrate in a glove box under a nitrogen atmosphere so that the light-emitting elements were not exposed to the air (a sealing material was applied around the elements, and UV treatment and heat treatment were performed at 80 °C for 1 hour during sealing). After that, the reliability of these light-emitting elements was measured. The measurement was performed at room temperature (an atmosphere maintained at 25 °C).

[0274] The element structures of the light-emitting elements 6 and 7 are summarized in the following table.

[0275]

Table 5

[0276] The current density-luminance characteristics of the light-emitting elements 6 and 7 are shown in FIG. 24, the luminance-current efficiency characteristics are shown in FIG. 25, the voltage-luminance characteristics are shown in FIG. 26, the luminance-external quantum efficiency characteristics are shown in FIG. 27, and the emission spectrum is shown in FIG. 28. The current density-luminance characteristics of the light-emitting elements 6 and 7 are shown in FIG. 24, the luminance-current efficiency characteristics are shown in FIG. 25, the voltage-luminance characteristics are shown in FIG. 26, the luminance-external quantum efficiency characteristics are shown in FIG. 27, and the emission spectrum is shown in FIG. 28. are shown in FIG. 28.

[0277] As described above, it was found that both the light-emitting elements 6 and 7 exhibit good luminous efficiency with a current efficiency of 20 cd / A or more in the vicinity of 1000 cd / m 2 Furthermore, the driving voltage is also in the 3 V range. Furthermore, the driving voltage is also in the 3 V range. , which is found to be very low compared to the tandem light-emitting element. Light-emitting element 6 and light-emitting element 7 at 1000 cd / m 2 shows a table summarizing the main characteristic values in the vicinity.

[0278]

Table 6

[0279] Also, from the emission spectrum, both orange emission derived from [Ir(dppm)2(acac)] and blue emission derived from 1,6mMemFLPAPrn were observed. From this, it can be seen that in light-emitting element 6 and light-emitting element 7, sufficient emission is obtained from both the first light-emitting layer 113a which is a fluorescent light-emitting layer and the second light-emitting layer 113c which is a phosphorescent light-emitting layer.

[0280] Thus, it can be seen that light-emitting element 6 and light-emitting element 7 are light-emitting elements having very well-balanced and good characteristics and can be fabricated simply and inexpensively. This result is due to the fact that exciton diffusion is suppressed and non-radiative deactivation of triplet excitons is reduced by using an exciplex as the energy donor of the phosphorescent light-emitting layer, and the generation of delayed fluorescence due to triplet-triplet annihilation in the host material of the fluorescent light-emitting layer contributes to the improvement of the emission efficiency. Also, by using the separation layer 113b, energy transfer at the interface from the phosphorescent light-emitting layer (the second light-emitting layer 113c) to the fluorescent light-emitting layer (the first light-emitting layer 113a) is also suppressed, which is also one of the reasons for showing good characteristics. Further, since light-emitting element 6 has better characteristics than light-emitting element 7, it can be seen that the separation layer 113b is preferably composed of a substance having hole-transporting properties and a substance having electron-transporting properties. Furthermore, They are more preferable configurations for forming an exciplex.

Example

[0281] In this example, the manufacturing method and characteristics of the light-emitting element 8, which is a light-emitting element of one aspect of the present invention, are shown. The light-emitting element 8 is a light-emitting element in which the first light-emitting layer 113a is on the cathode side and the second light-emitting layer 113c is on the anode side. The structural formula of the organic compound used in the light-emitting element 8 is shown below.

[0282]

Chemical formula

[0283] (Manufacturing method of the light-emitting element 8) On a high refractive index glass substrate with a refractive index n = 1.84, indium tin oxide (ITO) was sputtered to form a 110 nm film by a sputtering method to form the first electrode 101. The electrode area was 2 mm × 2 mm.

[0284] Next, as a pretreatment for forming a light-emitting element on the substrate, the substrate surface was washed with water and subjected to UV ozone treatment for 370 seconds.

[0285] After that, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to about 10 -4 Pa, and in the heating chamber of the vacuum evaporation apparatus, vacuum baking was performed at 190 °C for 60 minutes, and then the substrate was allowed to cool for about 30 minutes.

[0286] Next, with the surface on which the first electrode 101 is formed facing downward, the substrate on which the first electrode 101 is formed was fixed to a substrate holder provided in the vacuum evaporation apparatus, and the pressure was reduced to about 10 Pa, and then, on the first electrode 101, by a vapor deposition method using resistance heating, the above structural formula (i) was represented -4 and then 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) and molybdenum(VI) oxide are co-evaporated to form a hole injection layer 111. The film thickness is 30 nm, and the ratio of DBT3P-II to molybdenum oxide is adjusted to be 1:0.5 (by weight) (= DBT3P-II: molybdenum oxide). Subsequently, on the hole injection layer 111, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi) is formed into a film with a thickness of 20 nm to form a hole transport layer 112. Furthermore, on the hole transport layer 112, 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (v), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi), and bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,4-pentanedionato-κO,O')iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(acac)]) represented by the above structural formula (vii) are used in a weight ratio of 0.1:0.9:0.06 ( (= 2mDBTBPDBq-II: PCBBiF: [Ir(dmdppr-dmp)2(acac)]) and co-evaporated to form a light-emitting layer 113.

[0287] Subsequently, on the hole injection layer 111, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi) is formed into a film with a thickness of 20 nm to form a hole transport layer 112. Furthermore, on the hole transport layer 112, 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (v), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi), and bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,4-pentanedionato-κO,O')iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(acac)]) represented by the above structural formula (vii) are used in a weight ratio of 0.1:0.9:0.06 ( (= 2mDBTBPDBq-II: PCBBiF: [Ir(dmdppr-dmp)2(acac)]) and co-evaporated to form a light-emitting layer 113.

[0288] Furthermore, on the hole transport layer 112, 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (v), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi), and bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,4-pentanedionato-κO,O')iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(acac)]) represented by the above structural formula (vii) are used in a weight ratio of 0.1:0.9:0.06 ( (= 2mDBTBPDBq-II: PCBBiF: [Ir(dmdppr-dmp)2(acac)]) and co-evaporated to form a light-emitting layer 113. Subsequently, on the hole injection layer 111, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi) is formed into a film with a thickness of 20 nm to form a hole transport layer 112. Furthermore, on the hole transport layer 112, 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (v), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi), and bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,4-pentanedionato-κO,O')iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(acac)]) represented by the above structural formula (vii) are used in a weight ratio of 0.1:0.9:0.06 ( (= 2mDBTBPDBq-II: PCBBiF: [Ir(dmdppr-dmp)2(acac)]) and co-evaporated to form a light-emitting layer 113. Subsequently, on the hole injection layer 111, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi) is formed into a film with a thickness of 20 nm to form a hole transport layer 112. Furthermore, on the hole transport layer 112, 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (v), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi), and bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,4-pentanedionato-κO,O')iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(acac)]) represented by the above structural formula (vii) are used in a weight ratio of 0.1:0.9:0.06 ( (= 2mDBTBPDBq-II: PCBBiF: [Ir(dmdppr-dmp)2(acac)]) and co-evaporated to form a light-emitting layer 113. 2 Subsequently, on the hole injection layer 111, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi) is formed into a film with a thickness of 20 nm to form a hole transport layer 112. Furthermore, on the hole transport layer 112, 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (v), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi), and bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,4-pentanedionato-κO,O')iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(acac)]) represented by the above structural formula (vii) are used in a weight ratio of 0.1:0.9:0.06 ( ​​=2mDBTBPDBq-II:PCBBiF:[Ir(dmdppr-dmp)2(a were co-evaporated at 15 nm so as to obtain 2mDBTBPDBq-II:PCBBiF:[Ir(dmdppr-dmp)2(acac)]) to form the first phosphorescent emission layer 113c-1 , and subsequently, 2mDBTBPDBq-II, PCBBiF, and bis[2-(6-tert-butyl-4-pyrimidinyl-κN3)phenyl-κC]( represented by the above structural formula (viii) 2,4-pentanedionato-κ 2 O,O’)iridium(III) (abbreviation: [Ir(tB uppm)2(acac)]) were co-evaporated at a weight ratio of 0.5:0.5:0.06 (= 2mDBTB PDBq-II:PCBBiF:[Ir(tBuppm)2(acac)]) so as to obtain 5 nm to form the second phosphorescent emission layer 113c-2, thereby forming the second emission layer 113c which is a phosphorescent emission layer . Further, 2mDBTBPDBq-II and PCBBiF were co-evaporated at a weight ratio of 0.5:0.5 (= 2mDBTBPDBq-II:PCBBiF) so as to obtain 2 nm to form the separation layer 113b. Thereafter, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenz[c,g]carbazole (abbreviation: cgDBCzPA) represented by the above structural formula (iii), and N,N’-bis(3-methylphenyl)-N,N’-bis[3-(9-phenyl-9H-fluoren- 9-yl)phenyl]-pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPr n) represented by the above structural formula (iv) were co-evaporated at a weight ratio of 1:0.025 (= cgDBCzPA:1,6mMemFLPAPrn ) so as to obtain 20 nm to form the first emission layer 113a which is a fluorescent emission layer, thereby forming the emission layer 113 .

[0289] ​​​​In the second light-emitting layer 113c which is a phosphorescent light-emitting layer and the separation layer 113b, 2 mD BTBPDBq-II and PCBBiF form an exciplex. Also, the emission wavelength thereof is [I r(dmdppr-dmp)2(acac)] and [Ir(tBuppm)2(acac )], and it has a configuration with high energy transfer efficiency that overlaps with the absorption band on the longest wavelength side of .

[0290] Furthermore, the singlet excitation energy of cgDBCzPA, which is the host material of the fluorescent light-emitting layer (the first light-emitting layer 113a), is greater than the singlet excitation energy of 1,6mMemFLPAPrn, which is a fluorescent light-emitting substance, and the triplet excitation energy of cgDBCzPA is smaller than the triplet excitation energy of 1,6 mMemFLPAPrn. The fluorescent light-emitting layer (the first light-emitting layer 113a) has a configuration in which regeneration and emission of singlet excitons associated with triplet-triplet annihilation are likely to be obtained.

[0291] Thereafter, cgDBCzPA was formed into a film with a film thickness of 10 nm on the first light-emitting layer 113a which is a fluorescent light-emitting layer, and furthermore, bathophenanthroline (abbreviation : BPhen) represented by the above structural formula (ix) was formed into a film with a thickness of 15 nm to form an electron transport layer 114.

[0292] After forming the electron transport layer 114, then, lithium fluoride (LiF) was deposited to have a film thickness of 1 nm to form an electron injection layer 115, and finally, as the second electrode 1 02 that functions as a cathode, a silver-magnesium alloy (1:0.5) was deposited to have a film thickness of 1 nm and silver was deposited to have a film thickness of 150 nm to fabricate the light-emitting device 8 of this example. In the above-described deposition process , all depositions were performed using the resistance heating method. ​​​​

[0293] The element structure of the light-emitting element 8 is shown in the following table.

[0294]

Table 7

[0295] The light-emitting element 8 was sealed with a glass substrate in a glove box under a nitrogen atmosphere so that the light-emitting element was not exposed to the atmosphere (applying a sealing material around the element and performing UV treatment and heat treatment at 80°C for 1 hour during sealing), and then the characteristics of this light-emitting element were measured. Note that the measurement was performed at room temperature (atmosphere maintained at 25°C) using an integrating sphere. A table summarizing the characteristic values at a current density of 3. 75 mA / cm is shown. 2

[0296]

Table 8

[0297] The light-emitting element 8 showed good external quantum efficiency and power efficiency. Also, the driving voltage was 2.8 V, which is a very low value compared to tandem-type light-emitting elements.

[0298] Also, the emission spectrum of the light-emitting element 8 is shown in FIG. 29. From the emission spectrum, red emission derived from [Ir(d mdppr-dmp)2(acac)], green emission derived from [Ir(tBuppm)2( acac)] and blue emission derived from 1,6mMemFLPAPrn were all observed. From this, it can be seen that sufficient emission is obtained from both the first light-emitting layer 113a, which is a fluorescent light-emitting layer, and the second light-emitting layer 113c, which is a phosphorescent light-emitting layer.

[0299] Furthermore, this light-emitting element has a good color rendering property with an average color rendering index Ra of 87, and a small deviation duv (from the black body radiation locus), making it suitable for lighting applications. Also, the color temperature shows characteristics that match the standard of 2840K bulb color.

[0300] Thus, it can be seen that the light-emitting element 8 is a light-emitting element that can be manufactured simply and inexpensively while having well-balanced and good characteristics. This result is due to the use of an exciplex as the energy donor of the phosphorescent light-emitting layer, which suppresses exciton diffusion and reduces the non-radiative deactivation of triplet excitation energy, and the contribution of the generation of delayed fluorescence due to triplet-triplet annihilation in the host material of the fluorescent light-emitting layer to the improvement of the luminous efficiency.

Examples

[0301] In this example, the manufacturing method and characteristics of the light-emitting element 9, which is a light-emitting element of one aspect of the present invention, will be described. The structural formula of the organic compound used in the light-emitting element 9 is shown below.

[0302]

Chemical formula

[0303] (Manufacturing method of the light-emitting element 9) Indium tin oxide (ITSO) containing silicon oxide was deposited on a glass substrate by sputtering to form the first electrode 101. The film thickness was set to 110 nm, and the electrode area was set to 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as the anode of the light-emitting element.

[0304] Next, as a pretreatment for forming the light-emitting element on the substrate, the substrate surface was washed with water, and 200 ​​​​​After baking at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0305] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0306] Next, the first electrode 101 is formed so that the surface on which the first electrode 101 is formed faces downward. The substrate was fixed to a substrate holder installed in a vacuum deposition apparatus and was heated for 10 -4 Reduced to about Pa After pressing, a film represented by the above structural formula (i) was deposited on the first electrode 101 by a deposition method using resistance heating. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) By co-evaporating DBT3P-II and molybdenum oxide (VI), The hole injection layer 111 was formed. The thickness of the layer was set to 15 nm. The layer was made of DBT3P-II and molybdenum oxide. The weight ratio of DBT3P-II to molybdenum oxide was adjusted to 2:1 (=DBT3P-II:molybdenum oxide). Saved.

[0307] Next, on the hole injection layer 111, 3-[4-(9-phenylene oxide) represented by the above structural formula (ii) 9-phenyl-9H-carbazole (abbreviation: PCPPn) A film was formed so as to have a thickness of 20 nm to form the hole transport layer 112 .

[0308] Furthermore, on the hole transport layer 112, a 7-[4-(10-fluoro)- [phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and N,N'-bis(3-methylphenyl) -N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl] -pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn) in a weight ratio of 2: 0.1 (= cgDBCzPA: 1,6mMemFLPAPrn) and co-evaporated to form a first light-emitting layer 113a which is a fluorescent light-emitting layer. Next, 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenz [f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (v) and N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H -carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF) represented by the above structural formula (vi) are co-evaporated in a weight ratio of 0.4:1.6 (= 2mDBTBPDBq-II :PCBBiF) to form a separation layer 113b. The film thickness of the separation layer 113b was 2 nm. Then, 2mDBTBPDBq-II, PCBBiF, and (acetylacetonato)bis(4,6-diphenylpyrimidinato iridium(III) (abbreviation: [Ir(dppm)2(acac)]) represented by the above structural formula (xiv) are co-evaporated in a weight ratio of 0.8:1.2:0.12 (= 2mDBTBPDBq-II:PCBBiF:[Ir(d ppm)2(acac)]) to form a first phosphorescent light-emitting layer 113c -1, and then 2mDBTBPDBq-II, PCBBiF, and bis{2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3 phenyl-κC}(2,4-pentanedionato-κO,O')iridium(III) ( abbreviation: [Ir(ppm-dmp)2(acac)]) represented by the above structural formula (xv) are co-evaporated in a weight ratio of 1.6:0.4:0. phenyl-κC}(2,4-pentanedionato-κO,O')iridium(III) ( abbreviation: [Ir(ppm-dmp)2(acac)]) in a weight ratio of 1.6:0.4:0.​​​​​ 12(=2mDBTBPDBq-II:PCBBiF:[Ir(ppm-dmp)2(a were co-evaporated at 15 nm so as to obtain 12(=2mDBTBPDBq-II:PCBBiF:[Ir(ppm-dmp)2(a and the second phosphorescent light-emitting layer 113c-2 was formed, and the second light-emitting layer 113c which is a phosphorescent light-emitting layer was formed. As described above, in the light-emitting element 9, the light-emitting layer 113 is formed by the first light-emitting layer 113a and the second light-emitting layer 113c.

[0309] In the phosphorescent light-emitting layer (the second light-emitting layer 113c), 2mDBTBPDBq-II and PCBBiF form an exciplex. Further, the emission wavelength thereof overlaps with the absorption band on the longest wavelength side of [Ir(dppm)2 (acac)] and [Ir(ppm-dmp)2(acac)], and has a configuration with high energy transfer efficiency.

[0310] Furthermore, the singlet excitation energy of cgDBCzPA, which is the host material of the fluorescent light-emitting layer (the first light-emitting layer 113a), is larger than the singlet excitation energy of 1,6mMemFLPAPrn, which is a fluorescent light-emitting substance, and the triplet excitation energy of cgDBCzPA is smaller than the triplet excitation energy of 1,6 mMemFLPAPrn. The fluorescent light-emitting layer (the first light-emitting layer 113a) has a configuration in which regeneration and emission of singlet excitons due to triplet-triplet annihilation are easily obtained. mMemFLPAPrn, and there is a relationship such that the fluorescent light-emitting layer (the first light-emitting layer 113a) has a configuration in which regeneration and emission of singlet excitons due to triplet-triplet annihilation are easily obtained.

[0311] Thereafter, 2mDBTBPDBq-II was formed into a film with a thickness of 10 nm on the phosphorescent light-emitting layer (the second light-emitting layer 113c), and further, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (ix) was formed into a film with a thickness of 15 nm to form the electron transport layer 114.

[0312] After the electron transport layer 114 is formed, lithium fluoride (LiF) is then deposited to a thickness of 1 nm. The electron injection layer 115 was formed by vapor deposition so as to form a second electrode 116 which functions as a cathode. 102, silver (Ag) and magnesium (Mg) were co-evaporated in a weight ratio of 1:0.5 to form 1 After forming a film with a thickness of 100 nm, a silver film was formed with a thickness of 150 nm by sputtering. In this way, the light-emitting device 9 of this example was fabricated.

[0313] In the above-mentioned deposition process, the deposition was all performed by a resistance heating method.

[0314] The light emitting element 9 is placed in a glove box with a nitrogen atmosphere so that the light emitting element is not exposed to the atmosphere. The process of sealing the element with a glass substrate (applying a sealant around the element and applying UV light during sealing) After that, the reliability of the light-emitting device was measured. The measurements were carried out at room temperature (atmosphere maintained at 25°C).

[0315] The device structure of the light-emitting device 9 is summarized in the table below.

[0316] [Table 9]

[0317] FIG. 30 shows the current density-luminance characteristics of the light-emitting element 9, FIG. 31 shows the luminance-current efficiency characteristics, and FIG. The luminance characteristics are shown in FIG. 32, the luminance-external quantum efficiency characteristics in FIG. 33, and the emission spectrum in FIG. 34. .

[0318] As described above, the light-emitting element 9 has a light emission rate of 1000 cd / m despite having a structure without an intermediate layer. 2 Attached The current efficiency is about 70cd / A and the external quantum efficiency is about 22% or more. It was found that it can be shown. Also, the driving voltage is 2.9 V, which is very low compared to the tandem light-emitting element. It can be seen that it is low.

[0319]

Table 10

[0320] Also, from the emission spectrum, both the phosphorescence emission derived from [Ir(dppm)2(acac)] and [Ir(p pm-dmp)2(acac)] and the fluorescence emission derived from 1,6mMemFLPAPrn were observed. From this, it was found that sufficient emission was obtained from both the first emission layer 113a which is the fluorescence emission layer and the second emission layer 113c which is the phosphorescence emission layer. It was found that this is the case.

[0321] Thus, it was found that the light-emitting element 9 is a light-emitting element that can exhibit white light emission with very high luminous efficiency and can be manufactured simply and inexpensively. This result is due to the suppression of exciton diffusion by using an exciplex as the energy donor of the phosphorescence emission layer, resulting in a reduction in the non-radiative deactivation of triplet excitation energy, and the contribution of the improvement in luminous efficiency due to the generation of delayed fluorescence accompanying triplet-triplet annihilation in the host material of the fluorescence emission layer. Also, the light-emitting element 9 uses the separation layer 113b to suppress the energy transfer at the interface from the phosphorescence emission layer (the second emission layer 113c) to the fluorescence emission layer (the first emission layer 113a), and further good characteristics were obtained. Also, an element having the same element structure as the light-emitting element 9 and having a film thickness of the first electrode of 70 nm was formed on a glass substrate having a refractive index of 1.84 so that the emission area was 90 mm × 90 mm.

[0322] Also, an element having the same element structure as the light-emitting element 9 and having a film thickness of the first electrode of 70 nm was formed on a glass substrate having a refractive index of 1.84 so that the emission area was 90 mm × 90 mm. ​​​​​​​​Furthermore, an organic EL lighting device was fabricated in which the surface of the substrate on the side where light is emitted was subjected to frosting process. 。

[0323] The luminance-power efficiency characteristics of this organic EL lighting device are shown in Fig. 35. While meeting the standards of a color temperature of 2700K and d uv = 0.019 for a bulb color, it showed a very high efficiency of 140 lm / W in the vicinity of a luminance of 1500 cd / m 2 2.

Explanation of symbols

[0324] 102 Second electrode 103 EL layer 104 Hole injection layer 111 Hole injection layer 112 Hole transport layer 113 Light emitting layer 113a First light emitting layer 113b Separation layer 113c Second light emitting layer 113c-1 First phosphorescent light emitting layer 113c-2 Second phosphorescent light emitting layer 114 Electron transport layer 115 Electron injection layer 400 Substrate 401 First electrode 403 EL layer 404 Second electrode 405 Sealing material 406 Sealing material 407 Sealing substrate 412 Pad 420 IC chip 501 First electrode 502 Second electrode 511 First light emitting unit 512 Second light emitting unit 513 Charge generation layer 601 Driving circuit section (source line driving circuit) 602 Pixel section 603 Driving circuit section (gate line driving circuit) 604 Sealing Substrate 605 Sealing Material 607 Space 608 Wiring 609 FPC (Flexible Printed Circuit) 610 Element Substrate 611 FET for Switching 612 FET for Current Control 613 First Electrode 614 Insulator 616 EL Layer 617 Second Electrode 618 Light-Emitting Element 623 n-Channel FET 624 p-Channel FET 901 Housing 902 Liquid Crystal Layer 903 Backlight Unit 904 Housing 905 Driver IC 906 Terminal 951 Substrate 952 Electrode 953 Insulation Layer 954 Partition Layer 955 EL Layer 956 Electrode 1001 Substrate 1002 Underlying Insulating Film 1003 Gate Insulating Film 1006 Gate Electrode 1007 Gate Electrode 1008 Gate Electrode 1020 First Interlayer Insulating Film 1021 Second Interlayer Insulating Film 1022 Electrode 1024W First Electrode of Light-Emitting Element 1024R First Electrode of Light-Emitting Element 1024G First Electrode of Light-Emitting Element 1024B First Electrode of Light-Emitting Element 1025 Partition 1028 EL Layer 1029 Second Electrode of Light-Emitting Element 1031 Sealing Substrate 1032 Sealing material 1033 Transparent substrate 1034R Red colored layer 1034G Green colored layer 1034B Blue colored layer 1035 Black layer (black matrix) 1036 Overcoat layer 1037 Third interlayer insulating film 1040 Pixel section 1041 Driving circuit section 1042 Peripheral section 2001 Housing 2002 Light source 3001 Lighting device 5000 Display area 5001 Display area 5002 Display area 5003 Display area 5004 Display area 5005 Display area 7101 Housing 7103 Display section 7105 Stand 7107 Display section 7109 Operation key 7110 Remote control operation unit 7201 Main body 7202 Housing 7203 Display section 7204 Keyboard 7205 External connection port 7206 Pointing device 7210 Second display section 7301 Housing 7302 Housing 7303 Connecting section 7304 Display section 7305 Display section 7306 Speaker section 7307 Recording medium insertion section 7308 LED lamp 7309 Operation key 7310 Connection terminal 7311 Sensor 7401 Housing 7402 Display unit 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 9033 Fastener 9034 Switch 9035 Power switch 9036 Switch 9038 Operation switch 9630 Housing 9631 Display unit 9631a Display unit 9631b Display unit 9632a Touch panel area 9632b Touch panel area 9633 Solar cell 9634 Charge and discharge control circuit 9635 Battery 9636 DCDC converter 9637 Operation key 9638 Converter 9639 Button

Claims

【Claim 1】 It has at least a first light-emitting layer, a second light-emitting layer, and a separation layer provided between the first light-emitting layer and the second light-emitting layer between a pair of electrodes, The emission spectrum from the first light-emitting layer exists in a shorter wavelength region than the emission spectrum from the second light-emitting layer, The first light-emitting layer has at least a fluorescent light-emitting substance and a host material, The second light-emitting layer has at least a substance capable of converting triplet excitation energy into light emission, a first organic compound, and a second organic compound, A light-emitting device in which the first organic compound and the second organic compound form a first exciplex.

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