Electronic device, light-emitting device, electronic apparatus, and illumination device

Abstract

An electronic device with high light extraction efficiency or light confinement effect is provided. The electronic device has a first layer and a second layer between a first electrode and a second electrode, a first layer between the first electrode and the second layer, the first layer has a first organic compound and a first material, the refractive index of the thin film of the first organic compound is 1 or greater and 1.75 or less, the first material has electron accepting capacity, and the second layer has the function of emitting or absorbing light.

Description

Technology Field

[0001] One embodiment of the present invention relates to a novel electronic device. Or to an electronic device using an organic compound with a low refractive index. Or to a light-emitting device, an electronic device, and a lighting device having said electronic device.

[0002] Furthermore, one embodiment of the present invention is not limited to the above technical field. One embodiment of the present invention relates to an article, a method, or a method of production. Alternatively, the present invention relates to a process, a machine, a product, or a composition of matter. In particular, one embodiment of the present invention relates to an electronic device, a semiconductor device, a light-emitting device, a display device, a lighting device, a light-emitting element, and a method of production thereof. Background Technology

[0003] The commercialization of electronic devices such as light-emitting devices (organic EL devices) and organic solar cells that utilize electroluminescence (EL) using organic compounds is underway. The basic configuration of these electronic devices consists of a semiconductor layer containing an organic compound sandwiched between a pair of electrodes.

[0004] Such electronic devices are lightweight, flexible, and highly design-oriented. Research and development is actively underway due to various advantages, such as the feasibility of coating processes. In particular, since the light-emitting elements are self-emissive, they are suitable as flat panel display devices because using them as pixels offers advantages such as high visibility and eliminates the need for a backlight.

[0005] In such electronic devices, an organic semiconductor layer formed by thinning organic compounds is primarily formed; since the organic compound and layer structure have a significant impact on the organic semiconductor device, the selection of the organic compound and layer structure is important. Furthermore, in electronic devices that emit or absorb light, such as organic solar cells or organic EL devices, a structure with high light extraction efficiency or light confinement effect is important.

[0006] Various methods have been proposed to improve the light extraction efficiency of organic EL devices. For example, in Patent Document 1, the light extraction efficiency was improved by fabricating an uneven shape on a part of the electrode or EL layer. Prior art literature

[0007] Japanese Patent Publication No. JP2013-033706 The problem to be solved

[0008] In light-emitting devices such as organic EL devices, one method to improve light extraction efficiency is to control the refractive index between the substrate and the electrode and / or between the electrode and the EL layer. However, introducing a layer that controls the refractive index into an organic EL device complicates the process. Therefore, there is a need to develop layers and layer structures that can control the refractive index while having the function of an EL layer. In addition, there is a need to develop layers and layer structures with a high light confinement effect in organic solar cells as well.

[0009] Considering the above-described problems, one embodiment of the present invention aims to provide an electronic device with high light extraction efficiency. Alternatively, one embodiment of the present invention aims to provide an electronic device comprising a layer with a low refractive index. Alternatively, one embodiment of the present invention aims to provide an electronic device with a low driving voltage. Alternatively, one embodiment of the present invention aims to provide an electronic device with reduced power consumption. Alternatively, one embodiment of the present invention aims to provide an electronic device with high reliability. Furthermore, one embodiment of the present invention aims to provide an electronic device with high luminous efficiency. Alternatively, one embodiment of the present invention aims to provide a novel electronic device. Alternatively, one embodiment of the present invention aims to provide an electronic device with a high light confinement effect. Alternatively, one embodiment of the present invention aims to provide a novel semiconductor device.

[0010] Furthermore, the description of the aforementioned problem does not prevent the existence of other problems. Moreover, one embodiment of the present invention is not necessarily required to solve all of these problems. Problems other than those described above become naturally apparent from the description in the specification, etc., and problems other than those described above can be derived from the description in the specification, etc. means of solving the problem

[0011] One embodiment of the present invention is an electronic device having a first layer and a second layer between a first electrode and a second electrode, a first layer between the first electrode and the second layer, the first layer having a first organic compound and a first material, the refractive index of the thin film of the first organic compound being 1 or more and 1.75 or less, the first material having electron accepting capacity, and the second layer having a function of emitting or absorbing light.

[0012] In addition, another embodiment of the present invention is an electronic device having a first layer between a first electrode and a second electrode, wherein the first layer has a first organic compound and a first material, the first organic compound has a first framework and an electron-donating framework, and the first framework is a tetraarylmethane framework or a tetraarylsilane framework.

[0013] In the above configuration, it is preferable that the refractive index of the first layer be 1 or more and 1.75 or less. By adopting the above configuration, the light extraction efficiency or light confinement effect of the electronic device can be improved.

[0014] In addition, in the above composition, it is preferable that the aryl groups of the tetraarylmethane backbone and the tetraarylsilane backbone are each independently substituted or unsubstituted aryl groups having 6 to 13 carbon atoms. It is also more preferable that the aryl groups are substituted or unsubstituted phenyl groups. By adopting the above composition, an organic compound with a low refractive index and good carrier transport properties can be obtained. Furthermore, the aryl groups or phenyl groups may bond with each other to form a ring.

[0015] In addition, in the above configuration, it is preferable that the electron-donating backbone includes any one of a pyrrole backbone, an aromatic amine backbone, an acridine backbone, and an azepine backbone. By using the above configuration, the driving voltage of the electronic device can be reduced.

[0016] In addition, in the above configuration, it is preferable that the glass transition point (Tg) of the first organic compound is 100°C or higher. By using the above configuration, an electronic device with excellent heat resistance can be obtained.

[0017] In addition, in the above configuration, it is preferable that the refractive index of the first layer is lower than the refractive index of the second layer. By adopting the above configuration, the light extraction efficiency or light confinement effect of the electronic device can be improved.

[0018] In addition, another embodiment of the present invention is an electronic device having a first layer, a second layer, and a third layer between a first electrode and a second electrode, a first layer between the first electrode and the second layer, a second layer between the first layer and the third layer, the first layer having a first organic compound and a first material, the refractive index of the thin film of the first organic compound being 1 or greater and 1.75 or less, the first material having electron accepting properties, the third layer having a function of emitting or absorbing light, the refractive index of the first layer being lower than the refractive index of the second layer, and the refractive index of the first layer being lower than the refractive index of the third layer.

[0019] In addition, in the above configuration, it is preferable that the first organic compound has electron-donating properties. By making the above configuration, an electronic device with good carrier transport properties can be obtained.

[0020] In addition, in the above configuration, it is preferable for the first layer and the second layer to be in contact, and it is more preferable for the second layer and the third layer to be in contact. By making the above configuration, the difference in refractive index of each layer can be suppressed, thereby improving the light extraction efficiency or light confinement effect of the electronic device.

[0021] In addition, in the above configuration, it is preferable that the refractive index of the first layer is lower than the refractive index of the first electrode. By adopting the above configuration, the light extraction efficiency or light confinement effect of the electronic device can be improved.

[0022] In addition, in the above configuration, it is preferable that the volume ratio of the first material in the first layer is 0.01 or more and 0.3 or less with respect to the first organic compound. By adopting the above configuration, the light extraction efficiency or light confinement effect of the electronic device can be improved.

[0023] In addition, in the above composition, it is preferable that the first material includes any one of titanium oxide, vanadium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, and silver oxide. By making the above composition, an electronic device with good carrier transport properties can be obtained.

[0024] In addition, in the above composition, the first material is preferably one of 7,7,8,8-tetracyanoquinodimethane (abbreviated: TCNQ), 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated: F4TCNQ), and 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated: F6TCNNQ). By using the above composition, an electronic device with good carrier transport properties can be obtained.

[0025] In addition, it is preferable that the electronic device in the above configuration is an organic EL device or a solar cell.

[0026] Furthermore, another embodiment of the present invention is an electronic device having at least one of a light-emitting element of the above configuration, a housing, and a touch sensor. Furthermore, another embodiment of the present invention is a lighting device having at least one of an electronic device of each of the above configuration, a housing, a connection terminal, and a protective cover. Furthermore, an embodiment of the present invention includes not only a light-emitting device having an electronic device, but also an electronic device having a light-emitting device within its scope. Accordingly, the term "light-emitting device" in this specification refers to an image display device or a light source (including a lighting device). Additionally, a display module equipped with a connector, such as an FPC (Flexible Printed Circuit) or TCP (Tape Carrier Package), on a light-emitting element, a display module provided with a printed circuit board at the end of the TCP, or a display module in which an IC (Integrated Circuit) is directly mounted on an electronic device by the COG (Chip On Glass) method is also an embodiment of the present invention. Effects of the invention

[0027] According to one embodiment of the present invention, an electronic device with high light extraction efficiency can be provided. Alternatively, according to one embodiment of the present invention, an electronic device comprising a layer with a low refractive index can be provided. Alternatively, according to one embodiment of the present invention, an electronic device with a low driving voltage can be provided. Alternatively, according to one embodiment of the present invention, an electronic device with reduced power consumption can be provided. Alternatively, according to one embodiment of the present invention, an electronic device with high reliability can be provided. Alternatively, according to one embodiment of the present invention, an electronic device with high luminous efficiency can be provided. Alternatively, according to one embodiment of the present invention, a novel electronic device can be provided. Alternatively, according to one embodiment of the present invention, an electronic device with a high light confinement effect can be provided. Alternatively, according to one embodiment of the present invention, a novel semiconductor device can be provided.

[0028] Furthermore, the description of these effects does not interfere with the existence of other effects. Additionally, one embodiment of the present invention does not necessarily have to possess all of these effects. Furthermore, effects other than these become naturally apparent from the description in the specification, drawings, claims, etc., and effects other than these can be derived from the description in the specification, drawings, claims, etc. Brief explanation of the drawing

[0029] FIG. 1 is a schematic cross-sectional view of an electronic device of one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a light-emitting element of one embodiment of the present invention and a diagram explaining the optical path length. FIG. 3 is a schematic cross-sectional view of a light-emitting element of one embodiment of the present invention and a diagram explaining the correlation of energy levels according to the light-emitting layer. FIG. 4 is a schematic cross-sectional view of a light-emitting element of one embodiment of the present invention and a diagram explaining the correlation of energy levels according to the light-emitting layer. FIG. 5 is a conceptual diagram of an active matrix type light-emitting device according to one embodiment of the present invention. FIG. 6 is a conceptual diagram of an active matrix type light-emitting device according to one embodiment of the present invention. FIG. 7 is a conceptual diagram of an active matrix type light-emitting device according to one embodiment of the present invention. FIG. 8 is a schematic diagram of an electronic device according to one embodiment of the present invention. FIG. 9 is a schematic diagram of an electronic device according to one embodiment of the present invention. FIG. 10 is a drawing illustrating a lighting device according to one embodiment of the present invention. FIG. 11 is a drawing illustrating a lighting device according to one embodiment of the present invention. FIG. 12 is a drawing illustrating the refractive index according to an embodiment. FIG. 13 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting element according to an embodiment. FIG. 14 is a diagram illustrating the current density-voltage characteristics of a light-emitting element according to an embodiment. FIG. 15 is a diagram illustrating the external quantum efficiency-luminance characteristics of a light-emitting element according to an embodiment. FIG. 16 is a diagram illustrating the emission spectrum according to an embodiment. FIG. 17 is a diagram illustrating the external quantum efficiency-chromaticity x characteristics of a light-emitting element according to an embodiment. FIG. 18 is a diagram illustrating the relationship between the external quantum efficiency and the volume ratio of MoO3 according to an embodiment. FIG. 19 is a drawing illustrating the refractive index according to an embodiment. FIG. 20 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting element according to an embodiment. FIG. 21 is a diagram illustrating the current density-voltage characteristics of a light-emitting element according to an embodiment. FIG. 22 is a diagram illustrating the external quantum efficiency-luminance characteristics of a light-emitting element according to an embodiment. FIG. 23 is a diagram illustrating the emission spectrum according to an embodiment. FIG. 24 is a diagram illustrating the external quantum efficiency-chromaticity x characteristics of a light-emitting element according to an embodiment. FIG. 25 is a drawing illustrating the refractive index according to an embodiment. FIG. 26 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting element according to an embodiment. FIG. 27 is a diagram illustrating the current density-voltage characteristics of a light-emitting element according to an embodiment. FIG. 28 is a diagram illustrating the external quantum efficiency-luminance characteristics of a light-emitting element according to an embodiment. FIG. 29 is a diagram illustrating the emission spectrum according to an embodiment. FIG. 30 is a drawing illustrating the reliability test results according to an embodiment. FIG. 31 is a diagram illustrating the external quantum efficiency-chromaticity x characteristics of a light-emitting element according to an embodiment. FIG. 32 is a diagram illustrating the external quantum efficiency-chromaticity y characteristics of a light-emitting element according to an embodiment. Specific details for implementing the invention

[0030] 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 description below, and its form and details may be varied without departing from the spirit and scope of the present invention. Accordingly, the present invention is not to be interpreted as being limited to the description of the embodiments shown below.

[0031] In addition, the actual location, size, and range of each component shown in drawings, etc., may not be indicated to facilitate understanding. Therefore, the disclosed invention is not necessarily limited to the location, size, and range disclosed in drawings, etc.

[0032] In addition, ordinal numbers such as "first," "second," etc., attached in this specification, etc., are used for convenience and may not indicate the order of processes or stacking. Therefore, for example, "first" may be appropriately replaced with "second" or "third," etc. Furthermore, the ordinal numbers described in this specification, etc., may not coincide with the ordinal numbers used to specify an embodiment of the present invention.

[0033] In addition, in describing the composition of the invention using drawings in this specification and the like, reference numerals indicating the same thing may be used commonly even between different drawings.

[0034] Additionally, in this specification and others, the terms "film" and "layer" may be interchangeable. For example, the term "conductive layer" may be changed to the term "conductive film." Or, for example, the term "insulating film" may be changed to the term "insulating layer."

[0035] In addition, the refractive index n includes n Ordinary, which is the refractive index of an ordinary ray; n Extraordinary, which is the refractive index of an extraordinary ray; and n Average, which is the average of both. Where "refractive index" is simply written in this specification, it may be read as n Average when no anisotropic analysis has been performed, and as n Ordinary when anisotropic analysis has been performed. Furthermore, anisotropy is represented by the difference between n Ordinary and n Extraordinary. Also, n Average is the value obtained by multiplying the value of n Ordinary by 2 and dividing the sum of the value of n Extraordinary by 3.

[0036] In addition, in this specification, etc., room temperature refers to a temperature in the range of 0°C or higher and 40°C or lower.

[0037] (Embodiment 1)

[0038] In this embodiment, an electronic device of one form of the present invention is described below using FIG. 1.

[0039] <Example of Electronic Device Configuration 1>

[0040] The electronic device (50) has a pair of electrodes (electrode (11) and electrode (12)) and an organic semiconductor layer (20) between a pair of substrates (substrate (10) and substrate (15)). The organic semiconductor layer (20) has at least a carrier transport layer (30) and a functional layer (40). Additionally, the organic semiconductor layer (20) may have multiple functional layers.

[0041] It is preferable that the functional layer (40) of the electronic device (50) has the function of absorbing or emitting light. When light generated from the functional layer (40) is extracted from the electrode (11) side, the light passing through the substrate (10) passes through the electrode (11) and the carrier transport layer (30). Alternatively, when light entering the organic semiconductor layer (20) from the electrode (11) side is absorbed in the functional layer (40), the light passing through the substrate (10) passes through the electrode (11) and the carrier transport layer (30). In order for light generated from the functional layer (40) to be efficiently extracted or for light to be efficiently absorbed in the functional layer (40), it is preferable that the amount of light attenuated in the electrode (11) and the carrier transport layer (30) be small.

[0042] However, it is known that in an electronic device (50), light is attenuated in the organic semiconductor layer (20) by a attenuation mode called the aberrant mode. For example, when light is emitted from the functional layer (40), the light generated from the functional layer (40) is attenuated by the aberrant mode when it passes through or is reflected from the electrode (11).

[0043] It is known that if a layer with a low refractive index exists in the layer through which light passes, the attenuated light is reduced. In FIG. 1, the attenuated light can be suppressed by using a layer with a low refractive index as the carrier transport layer (30).

[0044] However, carrier transport layer (30) often requires carrier transportability or carrier injection properties. Therefore, carrier transport layer (30) uses a carrier-soluble or carrier-donating material. Since the carrier-soluble or carrier-donating material is often a material with a high refractive index, the carrier transport layer (30) has a high refractive index. In other words, it was difficult to obtain a layer with low refractive index while having carrier transportability. Furthermore, when the carrier-soluble or carrier-donating material is an organic compound, it is known that the refractive index decreases if the structure of the organic compound contains a saturated cyclic compound such as a cyclohexane backbone, but there was a problem with heat resistance.

[0045] Here, the inventors have discovered that by mixing an organic compound with a low refractive index with a carrier transport layer (30), a layer with carrier transport and a low refractive index can be produced even when using a material with a high refractive index and electron accepting capacity. Furthermore, they have discovered that by mixing an organic compound having either a tetraarylmethane backbone or a tetraarylsilane backbone and an electron-donating group with a carrier transport layer (30), a layer with carrier transport and a low refractive index can be produced even when using a material with a high refractive index and electron accepting capacity. They have also discovered that the organic compound has excellent heat resistance.

[0046] The refractive index of the organic compound with the low refractive index is preferably 1 or higher and 1.75 or lower, more preferably 1 or higher and 1.73 or lower, and even more preferably 1.70 or lower. By using the above configuration, a good electronic device with reduced attenuating light can be obtained.

[0047] It is preferable that the refractive index of an organic compound having either the tetraarylmethane backbone or the tetraarylsilane backbone and an electron-donating group be 1 or higher and 1.75 or lower, more preferably 1 or higher and 1.73 or lower, and even more preferably 1.70 or lower. By using the above configuration, an electronic device with good light extraction efficiency and reduced attenuating light can be obtained.

[0048] <Example of Electronic Device Configuration 2>

[0049] Hereinafter, a light-emitting element, which is an example of an electronic device of one embodiment of the present invention, will be described using FIG. 2.

[0050] Figure 2 (A) is a schematic cross-sectional view of a light-emitting element (150) of one form of the present invention.

[0051] A light-emitting element (150) has a substrate (200) and a substrate (210), a pair of electrodes (electrode (101) and electrode (102)) between the substrate (200) and the substrate (210), and an EL layer (100) provided between the pair of electrodes. The EL layer (100) has at least a light-emitting layer (130).

[0052] In addition, the EL layer (100) shown in (A) of FIG. 2 has functional layers such as a hole injection layer (111), a hole transport layer (112), an electron transport layer (118), and an electron injection layer (119), in addition to the light-emitting layer (130).

[0053] In addition, in this embodiment, among the pair of electrodes, electrode (101) is described as the positive electrode and electrode (102) as the negative electrode, but the configuration of the light-emitting element (150) is not limited thereto. That is, electrode (101) may be the negative electrode and electrode (102) may be the positive electrode, and the stacking of each layer between these electrodes may be done in the reverse order. That is, starting from the positive electrode side, the hole injection layer (111), hole transport layer (112), light-emitting layer (130), electron transport layer (118), and electron injection layer (119) may be stacked in that order.

[0054] In addition, in this embodiment, the electrode (101) (anode) side in FIG. 2 (A) is described as the side for extracting light, but the configuration of the light-emitting element (150) is not limited thereto. That is, the side for extracting light may be the electrode (102) (negative electrode) side, and light may also be extracted from both the electrode (101) and the electrode (102).

[0055] In addition, the configuration of the EL layer (100) is not limited to the configuration shown in (A) of FIG. 2, and may have at least a light-emitting layer (130), and may have a hole injection layer (111), a hole transport layer (112), an electron transport layer (118), and an electron injection layer (119), respectively, or may not have. In addition, the EL layer (100) may be configured to have a functional layer having functions such as reducing the injection barrier of holes or electrons, improving the transportability of holes or electrons, hindering the transportability of holes or electrons, suppressing the extinction phenomenon caused by electrodes, or suppressing the diffusion of excitons. In addition, each functional layer may be a single layer or may be a configuration in which multiple layers are stacked.

[0056] FIG. 2 (B) is a schematic cross-sectional view showing an example of the light-emitting layer (130) illustrated in FIG. 2 (A). The light-emitting layer (130) illustrated in FIG. 2 (B) may have a guest material (131) and a host material (132).

[0057] In order to efficiently obtain light emission from the light-emitting element (150), it is desirable that the light extraction efficiency of the light-emitting element (150) be high. However, as described above, it is known that the light extraction efficiency of an organic EL element is reduced by a decay mode called the aberrant mode. For example, in the light-emitting element (150), when light generated from the light-emitting layer (130) passes through or is reflected from the electrode (101), it is decayed by the aberrant mode.

[0058] In order to reduce light attenuation caused by the evanescent mode, there is a method to increase the thickness of the film of the layer between the light-emitting layer (130) and the electrode (101), for example, the hole injection layer (111) or the hole transport layer (112), but if the above configuration is used, there are problems such as the driving voltage increasing or the manufacturing cost increasing.

[0059] Here, in the light-emitting element (150), light generated from the light-emitting layer (130) is extracted to the outside, but it is known that if a layer with a low refractive index exists until the light generated from the light-emitting layer (130) passes through the substrate (200), the light extraction efficiency is improved.

[0060] Light generated from the light-emitting layer (130) passes through the hole injection layer (111), hole transport layer (112), electrode (101), and substrate (200) until it is extracted to the outside. Therefore, it is desirable for the refractive index of the hole injection layer (111) or the hole transport layer (112) to be low. In particular, it is desirable for the refractive index of the hole injection layer (111) in contact with the electrode (101) to be low.

[0061] However, in order to obtain hole injection characteristics in the hole injection layer (111), a material having electron acceptance is often mixed with an organic compound having electron donating properties. Since the electron acceptance material is often a material with a high refractive index, the hole injection layer (111) has a high refractive index. In other words, it was difficult to obtain a layer with a low refractive index while having hole injection properties. Furthermore, when the electron acceptance or electron donating material is an organic compound, it is known that the refractive index decreases if the structure of the organic compound contains a saturated cyclic compound such as a cyclohexane backbone, but there was a problem with heat resistance.

[0062] Here, the inventors have discovered that by using an organic compound with a low refractive index in the electron injection layer (111), a layer with a low refractive index and hole injection characteristics can be produced even when using a material with a high refractive index and electron accepting capacity. Furthermore, the inventors have discovered that by mixing an organic compound having at least one of a tetraarylmethane backbone and a tetraarylsilane backbone and an electron-donating group with the electron injection layer (111), a layer with a low refractive index and carrier transport capabilities can be produced even when using a material with a high refractive index and electron accepting capacity. Additionally, it has been discovered that the organic compound has excellent heat resistance. It is preferable that the glass transition point (Tg) of the organic compound be 100°C or higher.

[0063] The refractive index of the organic compound with the low refractive index is preferably 1 or higher and 1.75 or lower, more preferably 1 or higher and 1.73 or lower, and even more preferably 1.70 or lower. By making the above configuration, a light-emitting device with good light extraction efficiency can be obtained.

[0064] It is preferable that the organic compound having either of the tetraarylmethane backbone and the tetraarylsilane backbone and an electron-donating group has a refractive index of 1 or higher and 1.75 or lower, more preferably 1 or higher and 1.73 or lower, and even more preferably 1.70 or lower. By having the above composition, a light-emitting device with good light extraction efficiency can be obtained.

[0065] As described above, if a layer with a low refractive index exists between the light-emitting layer (130) and the substrate (200), the light extraction efficiency is improved. However, if a layer with a low refractive index is introduced in addition to the hole injection layer (111) and the hole transport layer (112), the number of layers to be fabricated increases, making the fabrication process of the light-emitting device more complex. However, in one embodiment of the present invention, since a layer with a low refractive index and hole injection characteristics can be fabricated, the light extraction efficiency of the light-emitting device can be improved by using the existing fabrication process, that is, while maintaining the number of layers to be fabricated.

[0066] Likewise, in one embodiment of the present invention, by using either a tetraarylmethane backbone or a tetraarylsilane backbone and an organic compound having an electron-donating group, a layer having a low refractive index and hole injection characteristics can be fabricated, so the light extraction efficiency of a light-emitting device can be improved using a conventional fabrication process, that is, without increasing the number of layers fabricated.

[0067] In addition, one embodiment of the present invention relates to an EL layer between an anode and a cathode. Therefore, it can be combined with other light extraction enhancement techniques, such as forming irregularities on a substrate.

[0068] In addition, one embodiment of the present invention preferably uses an organic compound having electron-donating properties in an organic compound with a low refractive index. By making the above configuration, the hole injection characteristics can be enhanced while lowering the refractive index of the hole injection layer (111), thereby providing a light-emitting device with good light extraction efficiency and a low driving voltage. It is more preferable that the organic compound has a tetraarylmethane backbone or a tetraarylsilane backbone.

[0069] Additionally, it is preferable that the refractive index of the hole injection layer (111) is lower than the refractive index of the light-emitting layer (130). By configuring it as above, attenuation of light emission from the light-emitting layer (130) due to evanescent waves can be reduced. Additionally, it is preferable that the refractive index of the hole injection layer (111) is lower than the refractive index of the hole transport layer (112), and that the refractive index of the hole transport layer (112) is lower than the refractive index of the light-emitting layer (130). By configuring it as above, the difference in refractive index between the light-emitting layer (130) and the hole injection layer (111) can be reduced, thereby further improving the light extraction efficiency.

[0070] In addition, to suppress the waveguide mode of the EL layer, it is desirable to have a small number of layers through which light generated from the light-emitting layer (130) passes. Therefore, while it is a desirable configuration in terms of light extraction efficiency for the light-emitting layer (130) to be in contact with the electrode (101), the light-emitting efficiency of the light-emitting layer (130) may be reduced due to the influence of carrier balance or plasmon effects. Accordingly, the hole injection layer (111) and the hole transport layer (112) are layers necessary to enable the EL layer to function efficiently. Therefore, it is desirable for the hole injection layer (111) and the hole transport layer (112) to be in contact, and it is even more desirable for the hole transport layer (112) and the light-emitting layer (130) to be in contact.

[0071] In addition, it is preferable that the refractive index of the hole injection layer (111) be lower than the refractive index of the electrode (101). By making the above configuration, since the relationship between the refractive index n HIL of the hole injection layer (111) and the refractive index n cat. of the electrode (101) becomes n cat. / n HIL > 1, total reflection when light passes from the hole injection layer (111) to the electrode (101) can be suppressed. That is, the waveguide mode can be suppressed. In addition, the attenuation of light caused by the ebenescent mode that occurs due to reflection can also be suppressed.

[0072] In addition, it is preferable that the refractive index of the hole injection layer (111) be 1 or higher and 1.80 or lower. More preferably, it is 1 or higher and 1.78 or lower, and even more preferably, 1 or higher and 1.75 or lower. By making the above configuration, good light extraction efficiency can be obtained.

[0073] In addition, in the hole injection layer (111), it is preferable to mix an organic compound having electron-donating properties with a material having electron-accepting properties. By making the above configuration, good hole injection characteristics can be obtained.

[0074] Here, the mixing ratio of the above-described organic compound and the electron-accepting material is preferably such that the volume ratio of the electron-accepting material is 0.01 or more and 0.3 or less relative to the organic compound. The inventors have discovered that by using this composition, even if a material with a high refractive index is used for the electron-accepting material, a hole injection layer (111) with a low refractive index can be produced by using an organic compound with a low refractive index for the organic compound.

[0075] The light attenuation caused by the aforementioned aberrant waves can also occur with respect to light incident on an electronic device. For example, when an electronic device according to one embodiment of the present invention is applied to a solar cell, the light attenuation caused by aberrant waves can be suppressed, thereby improving the light confinement effect of the solar cell. Therefore, an electronic device according to one embodiment of the present invention can be suitably used in a solar cell. In this case, the functional layer (40) in the electronic device (50) shown in FIG. 1 may be read as an active layer, a light absorption layer, or a photovoltaic layer.

[0076] <Organic compound used in hole injection layer (111)>

[0077] Here, an organic compound suitable for use in the hole injection layer (111) is described.

[0078] It is preferable to use an organic compound with a low refractive index in the hole injection layer (111). Here, the refractive index of the polymer is represented by the Lorentz-Lorenz equation (mathematical equation (1)) shown below.

[0079] [Mathematical Formula 1]

[0080]

[0081] Mathematical formula (2) is obtained by modifying mathematical formula (1).

[0082] [Mathematical Formula 2]

[0083]

[0084] Among mathematical formulas (1) and (2), n is the refractive index, α is the polarization index, N is the number of molecules per unit volume, ρ is the density, and N A ε₀ represents Avogadro's number, M represents the molecular weight, V₀ represents the molar volume, and [R] represents the atomic refraction.

[0085] To make the refractive index n smaller than in mathematical formula (2), it is good to make φ smaller, and to make φ smaller than in mathematical formula (1), it is good to make the atomic refraction [R] smaller. That is, to make the refractive index n smaller, it is good to select an organic compound in which the atomic refraction [R] is reduced.

[0086] Since the above formula is for polymers, it is expected that there will be a slight difference in the calculated value when applied to low-molecular-weight compounds, but since the trend is thought to be almost the same, it is desirable to select an organic compound with a reduced atomic refractive index [R] for use in the hole injection layer (111). In addition, it is desirable for the hole injection layer (111) to have hole injection characteristics. Therefore, it is more desirable for the organic compound used in the hole injection layer (111) to additionally have a π-conjugation within the molecule, such as an aromatic compound, and to have electron-donating properties. By selecting such an organic compound, it is possible to produce a hole injection layer (111) with a low refractive index and excellent hole injection characteristics.

[0087] In bonds involving fluorine-containing substituents such as fluoro groups or trifluoromethyl groups, cyclohexyl groups, or aromatic rings, sp 3 If the structure has a truncated conjugate between the directional rings, represented by hybrid orbitals, the atomic refractive index [R] tends to decrease. Additionally, organic compounds having a comparative hydrocarbon tend to have a smaller atomic refractive index [R] because the conjugated system is not extended throughout the entire molecule. Therefore, the organic compound used in the hole injection layer (111) is preferably an organic compound having the above-mentioned substituent or bond.

[0088] The organic compound used in the hole injection layer (111) may suitably be an organic compound having an aromatic amine backbone, a pyrrole backbone, or a thiophene backbone, or an organic compound having an aromatic ring with bulky substituents such as a methyl group, a t-butyl group, or an isopropyl group. The organic compound has a π-conjugated system in its molecule and tends to have a low refractive index.

[0089] In the bonding involving the aforementioned directional rings, examples of structures in which the conjugate between the directional rings is cut include the tetraarylmethane framework represented by the following general formula (100), the tetraarylsilane framework represented by the general formula (101), or the cyclohexyl framework. Since the tetraarylmethane framework or the tetraarylsilane framework has a low refractive index and good heat resistance compared to the cyclohexyl framework, it can be suitablely used for the hole injection layer (111). In addition, since a thin film can be easily formed by vacuum deposition, it can be suitablely used for electronic devices such as organic EL.

[0090] [Chemical Formula 1]

[0091]

[0092] In addition, it is preferable that the organic compound used in the hole injection layer (111) has electron-donating properties. Examples of frameworks having electron-donating properties include the aromatic amine framework shown in the following general formulas (200 to 220) or the π-electron-excess type complex aromatic ring framework. X in the general formulas (210 to 213) represents oxygen or sulfur.

[0093] [Chemical Formula 2]

[0094]

[0095] The aforementioned aromatic amine backbone (specifically, for example, a triarylamine backbone) and π-electron excess complex aromatic ring backbone (specifically, for example, a ring having a furan backbone, a thiophene backbone, a pyrrole backbone, an azepine backbone, or an acridine backbone) may have substituents. As the substituents, alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups having 3 to 6 carbon atoms, or substituted or unsubstituted aryl groups having 6 to 12 carbon atoms may be selected. Specifically, examples of alkyl groups having 1 to 6 carbon atoms include methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, n-hexyl groups, etc. Additionally, specifically examples of cycloalkyl groups having 3 to 6 carbon atoms include cyclopropyl groups, cyclobutyl groups, cyclopentyl groups, cyclohexyl groups, etc. In addition, specific examples of aryl groups having 6 to 12 carbon atoms include phenyl groups, naphthyl groups, and biphenyl groups. Furthermore, the above substituents may bond with each other to form a ring. An example of this is when the carbon at the 9th position of the fluorene skeleton has two phenyl groups as substituents, and the phenyl groups bond with each other to form a spirofluorene skeleton. In addition, the non-substituent case is advantageous in terms of ease of synthesis and raw material cost.

[0096] As described above, the electron-donating framework is preferably an acridine framework, such as an aromatic amine framework, a pyrrole framework, an azepine framework, or an odd-circle ring framework. Since these frameworks have good electron-donating properties and low atomic refractive index [R], it is possible to obtain an organic compound with excellent electron-donating properties and a low refractive index by having these frameworks in the molecule.

[0097] Also, Ar 1 or Ar 8 Each represents, independently, an aryl group having 6 to 13 carbon atoms, an aromatic amine backbone represented by the general formulas (200 to 220) described above, or a π-electron excess complex aromatic backbone. The aryl group may have substituents, and the substituents may bond to form a ring. An example of this is when the carbon at the 9th position of the fluorenyl group has two phenyl groups as substituents, and the phenyl groups bond to each other to form a spiroflurene backbone. Specific examples of the aryl group having 6 to 13 carbon atoms include, for instance, a phenyl group, a naphthalenyl group, and a fluorenyl group. Furthermore, when the aryl group has substituents, the substituents may be selected from an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Specifically, examples of alkyl groups having 1 to 6 carbon atoms include methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, n-hexyl groups, etc. Additionally, specifically examples of cycloalkyl groups having 3 to 6 carbon atoms include cyclopropyl groups, cyclobutyl groups, cyclopentyl groups, cyclohexyl groups, etc. Furthermore, specific examples of aryl groups having 6 to 12 carbon atoms include phenyl groups, naphthyl groups, etc.

[0098] Also, Ar 1 or Ar 8The aryl group represented by [formula] may be, for example, a group represented by the following structural formula. In addition, the groups that can be used as aryl groups are not limited to these.

[0099] [Chemical Formula 3]

[0100]

[0101] Also, Ar 1 or Ar 8 In the case of this aryl group, it is preferable that the aryl group be a substituent with a relatively small expansion of the π-conjugation system, such as a substituted or unsubstituted aryl group having 6 to 13 carbon atoms, and it is more preferable that it be a substituted or unsubstituted phenyl group. Substituents with a small π-conjugation system tend to have a small atomic refractive index [R]. On the other hand, organic compounds with a small π-conjugation system, such as alkenes, are not suitable for electronic devices because they lack carrier transportability. Therefore, an organic compound having carrier transportability and a small π-conjugation system, such as an aryl group having 6 to 13 carbon atoms, particularly a phenyl group, is preferred as an organic compound used in the hole injection layer (111). In addition, substituents of odd-numbered rings are preferred because they have a small atomic refractive index [R].

[0102] In addition, among the general formulas (200 to 220), R 1 to R 11Each represents, independently, any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specifically, examples of alkyl groups having 1 to 6 carbon atoms include methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, n-hexyl groups, etc. Additionally, specifically examples of cycloalkyl groups having 3 to 6 carbon atoms include cyclopropyl groups, cyclobutyl groups, cyclopentyl groups, cyclohexyl groups, etc. Additionally, specific examples of aryl groups having 6 to 13 carbon atoms include phenyl groups, naphthyl groups, biphenyl groups, fluorenyl groups, etc. Furthermore, the above-mentioned aryl groups or phenyl groups may have substituents, and said substituents may bond with each other to form a ring. As the above substituent, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms may be selected. Specifically, examples of alkyl groups having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. Also, specifically examples of cycloalkyl groups having 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. Additionally, specific examples of aryl groups having 6 to 12 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, etc.

[0103] Also, R 1 to R 11 The hydrogen, alkyl, or aryl group represented by may be, for example, a group represented by the following general formulas (R-1 to R-27). In addition, the groups that can be used as alkyl or aryl groups are not limited to these.

[0104] [Chemical Formula 4]

[0105]

[0106] In addition, among the general formulas (200 to 220), Ar 9 or Ar 13 ... represents an arylene group having 6 to 13 carbon atoms, and the arylene group may have substituents, and the substituents may bond with each other to form a ring. An example of this is when the carbon at the 9th position of the fluorenyl group has two phenyl groups as substituents, and the phenyl groups bond with each other to form a spirofluorene backbone. Specific examples of the arylene group having 6 to 13 carbon atoms include, for instance, a phenylene group, a naphthalenediyl group, a biphenylene group, a fluorendiyl group, etc. Furthermore, when the arylene group has substituents, the substituents may be selected from an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Specifically, examples of alkyl groups having 1 to 6 carbon atoms include methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, n-hexyl groups, etc. Additionally, specifically examples of cycloalkyl groups having 3 to 6 carbon atoms include cyclopropyl groups, cyclobutyl groups, cyclopentyl groups, cyclohexyl groups, etc. Furthermore, specific examples of aryl groups having 6 to 12 carbon atoms include phenyl groups, naphthyl groups, biphenyl groups, etc.

[0107] Also, Ar 9 or Ar 13 The arylene group represented by can be, for example, a group represented by the following structural formulas (Ar-12 to Ar-25). In addition, Ar 9 or Ar 13 The devices that can be used as such are not limited to these.

[0108] [Chemical Formula 5]

[0109]

[0110] As described above, the organic compound used in the hole injection layer (111) is preferably an organic compound having a tetraarylmethane backbone or a tetraarylsilane backbone and electron-donating properties. Examples of the above organic compounds include 9-(4-t-butylphenyl)-3,4-ditrityl-9H-carbazole (abbreviated: CzC), 9-(4-t-butylphenyl)-3,4-ditriphenylsilyl-9H-carbazole (abbreviated: CzSi), 4,4,8,8,-12,12-hexa-p-toluyl-4H-8H-12H-12C-aza-dibenzo[cd,mn]pyrene (abbreviated: FATPA), 4,4'-bis(dibenzo-azepine-1-yl)-biphenyl (abbreviated: BazBP), 4,4'-bis(dihydro-dibenzo-azepine-1-yl)-biphenyl (abbreviated: HBazBP), and 4,4'-(diphenylmethylene)bis(N,N-diphenylamine) (abbreviated: Examples include TCBPA), 4,4'-(diphenylsilanediyl)bis(N,N-diphenylamine) (abbreviated: TSBPA), etc. Their structural formulas are shown below. Furthermore, organic compounds having the above tetraarylmethane backbone or tetraarylsilane backbone and electron-donating properties are not limited thereto. Their structural formulas are shown below.

[0111] [Chemical Formula 6]

[0112]

[0113] In addition, a low-molecular-weight organic compound can be suitably used in an electronic device according to one embodiment of the present invention. By using a low-molecular-weight organic compound, all layers included in the EL layer (100) can be formed by vacuum deposition, so the manufacturing process can be simplified.

[0114] <<Improvement of light extraction efficiency by adjusting optical path length>>

[0115] In addition, in an electronic device which is one embodiment of the present invention, the light extraction efficiency can be further improved by controlling the optical path length. Among the light emitted from the light-emitting layer (130), light of a desired wavelength can be efficiently extracted.

[0116] For example, in order to efficiently extract light of a desired wavelength (wavelength: λ) obtained from the light-emitting layer (130), it is preferable to adjust the optical distance from the interface between the electrode (101) and the hole injection layer (111) to the region (light-emitting region (134)) in the light-emitting layer (130) where light of the desired wavelength is obtained to be (2m'-1)λ4 (where m' is a natural number). In addition, the light-emitting region referred to here indicates the recombination region of holes and electrons in the light-emitting layer (130).

[0117] By performing such optical adjustment, the attenuation of light due to the evanescent mode can be reduced, thereby improving the light extraction efficiency from the light-emitting layer (130).

[0118] In addition, it is preferable to adjust the optical distance from the interface between the substrate (200) and the electrode (101) to the region (emission region (134)) in the light-emitting layer (130) where light of a desired wavelength is obtained to be mλ2 (where m is a natural number). By performing such optical adjustment, the attenuation of light due to the evanescent mode can be reduced, thereby improving the light extraction efficiency from the light-emitting layer (130).

[0119] In order to perform the above optical adjustment, it is necessary to adjust the film thickness of the hole injection layer (111) or the hole transport layer (112). However, if the refractive index of the hole injection layer (111) is high, the optical path length tends to become longer, so it may be difficult to adjust the optical path length, or the driving voltage may increase as the film thickness of the hole injection layer (111) becomes thicker. However, in one embodiment of the present invention, since the refractive index of the hole injection layer (111) is low, it is easy to control the optical path length, and the film thickness can be made thin. Therefore, not only is the light extraction efficiency from the light-emitting layer (130) improved, but the manufacturing process of the light-emitting device can also be simplified, and a light-emitting device having a low driving voltage can be realized.

[0120] The light attenuation caused by the aforementioned aberrant waves can also occur with respect to light incident on an electronic device. For example, when an electronic device according to one embodiment of the present invention is applied to a solar cell, the light attenuation caused by aberrant waves can be suppressed, thereby improving the light confinement effect of the organic solar cell. Therefore, an electronic device according to one embodiment of the present invention can be suitably used in a solar cell. In this case, the functional layer (40) in the electronic device (50) shown in FIG. 1 may be read as an active layer.

[0121] In addition, although the above-described structure describes a configuration for efficiently extracting light by adjusting the optical path length of a light-emitting element to the desired wavelength λ of light, an example of its application to a solar cell is described using FIG. 1. It is preferable to adjust the film thickness between a pair of electrodes, specifically the film thickness of the organic semiconductor layer (20) in FIG. 1, so that the optical path length is different from the wavelength λ' of light incident on the electronic device (50). By making the above configuration, light incident on the electronic device (50) can be efficiently confined within the electronic device (50). Furthermore, in an electronic device of one embodiment of the present invention, light attenuation caused by evanescent waves can be suppressed, thereby enabling a more efficient light confinement effect.

[0122] Ingredients

[0123] Next, details of the components of a light-emitting element, which is an example of an electronic device according to one embodiment of the present invention, will be described below.

[0124] <<Luminous Layer>>

[0125] The light-emitting layer (130) preferably has at least a host material (131) and additionally a guest material (132). Additionally, as described below, the host material (131) may have an organic compound (131_1) and an organic compound (131_2). In the light-emitting layer (130), the host material (131) is present in the largest weight ratio, and the guest material (132) is dispersed within the host material (131). When the guest material (132) is a fluorescent compound, it is preferable that the S1 level of the host material (131) (organic compound (131_1) and organic compound (131_2)) of the light-emitting layer (130) is lower than the S1 level of the guest material (guest material (132)) of the light-emitting layer (130). Additionally, when the guest material (132) is a phosphorescent compound, it is preferable that the T1 level of the host material (131) (organic compound (131_1) and organic compound (131_2)) of the light-emitting layer (130) be higher than the T1 level of the guest material (guest material (132)) of the light-emitting layer (130).

[0126] As for the organic compound (131_1), it is preferable to have a complex aromatic skeleton having 1 to 20 carbon atoms containing two or more nitrogen atoms. In particular, it is preferable to have a compound having a pyrimidine skeleton and a triazine skeleton. As for the organic compound (131_1), a material with higher electron transport than hole transport (electron transport material) may be used, and 1×10 -6 cm 2 It is desirable that the material has an electron mobility of / Vs or higher.

[0127] Specifically, for example, heterocyclic compounds having a diazine backbone such as 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviated: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviated: 4,6mDBTP2Pm-II), and 4,6-bis[3-(9H-carbazole-9-yl)phenyl]pyrimidine (abbreviated: 4,6mCzP2Pm), or 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated: PCCzPTzn), Heterocyclic compounds having a triazine backbone, a pyrimidine backbone, or a triazole backbone, such as 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated: mBnfBPTzn), 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (abbreviated: T2T), 2,4,6-tris[3'-(pyridine-3-yl)-biphenyl-3-yl]-1,3,5-triazine (abbreviated: TmPPPyTz), and 9-[4-(3,5-diphenyl-1H-1,2,4-triazole-1-yl)]phenyl-9H-carbazole (abbreviated: CzTAZ(1H)), are desirable because they are stable and reliable. Furthermore, complex ring compounds having the above framework exhibit high electron transport and contribute to a reduction in driving voltage. The materials described herein are primarily 1×10⁻⁶ -6 cm 2 It is a material having an electron mobility of / Vs or higher. Additionally, any material other than the above may be used if it has higher electron transport than hole transport.

[0128] In addition, as the organic compound (131_1), compounds such as pyridine derivatives, pyrazine derivatives, pyridazine derivatives, bipyridine derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, and purine derivatives may also be used. Such organic compounds are 1×10 -6 cm 2 It is desirable that the material has an electron mobility of / Vs or higher.

[0129] Specifically, for example, heterocyclic compounds having a pyridine backbone such as vasopenanthroline (abbreviation: BPhen) and vasocuproin (abbreviation: BCP), or 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), Complex cyclic compounds having a pyrazine backbone, such as 2-[4-(3,6-diphenyl-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated: 6mDBTPDBq-II), and 2-[3-(3,9'-bi-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated: 2mCzCzPDBq), or Heterocyclic compounds having a pyridine backbone, such as 3,5-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviated: 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviated: TmPyPB), may also be used. In addition, polymeric compounds such as poly(2,5-pyridindiyl) (abbreviated: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviated: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviated: PF-BPy) may also be used. Furthermore, any material other than the above may be used as long as it has higher electron transport than hole transport.

[0130] As for the organic compound (131_2), it is preferable to have a complex aromatic skeleton having 1 to 20 carbon atoms containing two or more nitrogen atoms. In particular, a nitrogen-containing complex five-membered ring skeleton is preferred. Examples include an imidazole skeleton, a triazole skeleton, and a tetrazole skeleton. Additionally, as for the organic compound (131_2), a material with higher hole transportability than electron transportability (hole transportable material) may be used, and 1×10 -6 cm 2 It is preferable that the material be having a hole mobility of / Vs or greater. In addition, the hole transporting material may be a polymer compound.

[0131] Specifically, for example, 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 9-[4-(4,5-diphenyl-4H-1,2,4-triazole-3-yl)phenyl]-9H-carbazole (abbreviation: CzTAZ1), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), etc. may be used.

[0132] As for the organic compound (131_2), other compounds having a nitrogen-containing complex five-membered ring skeleton or a tertiary amine skeleton may also be suitably used. Specifically, pyrrole skeletons or aromatic amine skeletons may be used. Examples include indole derivatives, carbazole derivatives, and triarylamine derivatives. Additionally, as for the organic compound (131_2), a material with higher hole transportability than electron transportability (hole transportable material) may be used, and 1×10 -6 cm 2 It is preferable that the material be having a hole mobility of / Vs or greater. In addition, the hole transporting material may be a polymer compound.

[0133] Specifically, as materials with high hole transportability, aromatic amine compounds include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviated: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviated: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviated: DPA3B).

[0134] In addition, as carbazole derivatives, specifically, 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviated: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviated: PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviated: PCzTPN2), 3-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated: PCzPCA1), 3,6-bis[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated: PCzPCA2), Examples include 3-[N-(1-naphthyl)-N-(9-phenylcarbazole-3-yl)amino]-9-phenylcarbazole (abbreviated: PCzPCN1), 4,4'-bis(9-carbazolyl)-2,2'-dimethyl-biphenyl (abbreviated: dmCBP), etc.

[0135] In addition, as carbazole derivatives, 4,4'-di(N-carbazolyl)biphenyl (abbreviated: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviated: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviated: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, etc. can be used.

[0136] In addition, N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviated: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviated: DPhPA), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviated: YGAPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviated: PCAPA), N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazole-3-amine (abbreviated: PCAPBA), N,9-diphenyl-N-(9,10-diphenyl-2-anthryl)-9H-carbazole-3-amine (abbreviated: 2PCAPA), 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviated: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviated: DPCzPA), N,N,N',N',N'',N'',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviated: DBC1), 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane (abbreviated: TAPC), etc. may be used.

[0137] In addition, polymer compounds such as poly(N-vinylcarbazole) (abbreviated: PVK), poly(4-vinyltriphenylamine) (abbreviated: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviated: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviated: Poly-TPD) may also be used.

[0138] In addition, materials with high hole transport include, for example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated: TPD), 4,4',4''-tris(carbazole-9-yl)triphenylamine (abbreviated: TCTA), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviated: 1'-TNATA), 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviated: TDATA), and 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviated: MTDATA), 4,4'-bis[N-(spyro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazole-3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazole-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-Triphenyl-N,N',N''-Tris(9-phenylcarbazole-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluorene-2-yl)-9-phenyl-9H-carbazole-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]fluorene-2-amine (abbreviation: PCBAF), Aromatic amine compounds such as N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]spiro-9,9'-bifluorene-2-amine (abbreviation: PCBASF), 2-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazole-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), and N,N'-bis[4-(carbazole-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F). You can use the back. In addition, amine compounds, carbazole compounds, etc., such as 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated: PCPN), 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviated: PCPPn), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated: PCCP), 1,3-bis(N-carbazolyl)benzene (abbreviated: mCP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated: CzTP), 3,6-di(9H-carbazole-9-yl)-9-phenyl-9H-carbazole (abbreviated: PhCzGI), and 2,8-di(9H-carbazole-9-yl)-dibenzothiophene (abbreviated: Cz2DBT) may be used. Among the compounds mentioned above, the pyrrole skeleton,Compounds having an aromatic amine backbone are desirable because they are stable and reliable. In addition, compounds having said backbone have high hole transport, which contributes to a reduction in driving voltage.

[0139] In addition, in the light-emitting layer (130), there are no particular limitations on the guest material (132), but as a fluorescent compound, anthracene derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, phenothiazine derivatives, etc. are preferred, and for example, the following materials may be used.

[0140] Specifically, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviated: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviated: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviated: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviated: 1,6mMemFLPAPrn), N,N'-Bis[4-(9-phenyl-9H-fluorene-9-yl)phenyl]-N,N'-Bis(4-tert-butylphenyl)pyrene-1,6-diamine (abbreviation: 1,6tBu-FLPAPrn), N,N'-Diphenyl-N,N'-Bis[4-(9-phenyl-9H-fluorene-9-yl)phenyl]-3,8-dicyclohexylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-Bis[4-(9H-carbazole-9-yl)phenyl]-N,N'-Diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-diphenyl-2-anthyl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthyl)phenyl]-9H-carbazole-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-Diphenyl-N-[4-(9,10-Diphenyl-2-Anthryl)phenyl]-9H-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'''-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazole-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 6, Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), Rubrene, 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (abbreviation: TBRb), Nyred, 5,12-Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedynitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedynitrile (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)acenaphthor[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedynitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedynitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedynitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedynitrile (abbreviation: BisDCJTM), Examples include 5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene.

[0141] As guest material (132) (phosphorescent compound), iridium, rhodium, or platinum-based organometallic complexes or metal complexes may be used, and among these, organoiridium complexes, for example, iridium-based orthometallic complexes are preferred. Examples of orthometallic ligands may include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, or isoquinoline ligands. Examples of metal complexes may include platinum complexes having porphyrin ligands.

[0142] As a substance having a blue or green emission peak, for example, tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazole-3-yl-κN 2Organometallic iridium complexes having a 4H-triazole backbone, such as ]phenyl-κC}iridium(III) (abbreviated: Ir(mpptz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazoleto)iridium(III) (abbreviated: Ir(Mptz)3), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazoleto]iridium(III) (abbreviated: Ir(iPrptz-3b)3), and tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazoleto]iridium(III) (abbreviated: Ir(iPr5btz)3), or Organometallic iridium complexes having a 1H-triazole backbone such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazoleto]iridium(III) (abbreviated: Ir(Mptz1-mp)3) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazoleto)iridium(III) (abbreviated: Ir(Prptz1-Me)3), or fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviated: Ir(iPrpmi)3) and tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenantridinato]iridium(III) (abbreviated: Ir(dmpimpt-Me)3), Tris{2-[1-(4-cyano-2,6-diisobutylphenyl)-1H-benzimidazole-2-yl-k N 3 Organometallic iridium complexes having an imidazole backbone such as ]phenyl-kC}iridium(III)(Ir(pbi-diBuCNp)3) or bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]Iridium(III)tetrakis(1-pyrazolyl)borate (abbreviated: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2' ]Iridium(III)picolinate (abbreviated: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinate-N,C 2'}Iridium(III)picolinate (abbreviation: Ir(CF3ppy)2(pic)), bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2' Examples of organometallic iridium complexes include those having a phenylpyridine derivative having an electron-withdrawing group, such as iridium(III) acetylacetonate (abbreviated: FIr(acac)), as a ligand. Among those mentioned above, organometallic iridium complexes having a nitrogen-containing five-membered heterocyclic skeleton, such as a 4H-triazole backbone, a 1H-triazole backbone, and an imidazole backbone, are particularly preferred because they have high triplet excited energy and excellent reliability and luminescence efficiency.

[0143] In addition, substances having a green or yellow emission peak include, for example, tris(4-methyl-6-phenylpyrimidineto)iridium(III) (abbreviated: Ir(mppm)3), tris(4-t-butyl-6-phenylpyrimidineto)iridium(III) (abbreviated: Ir(tBuppm)3), (acetylacetonate)bis(6-methyl-4-phenylpyrimidineto)iridium(III) (abbreviated: Ir(mppm)2(acac)), (acetylacetonate)bis(6-tert-butyl-4-phenylpyrimidineto)iridium(III) (abbreviated: Ir(tBuppm)2(acac)), (acetylacetonate)bis[4-(2-norvonyl)-6-phenylpyrimidineto]iridium(III) (abbreviated: Ir(nbppm)2(acac)), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III)(abbreviated: Ir(mpmppm)2(acac)), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN 3Organometallic iridium complexes having a pyrimidine backbone such as ]phenyl-κC}iridium(III) (abbreviated: Ir(dmppm-dmp)2(acac)) and (acetylacetonato)bis(4,6-diphenylpyrimidineto)iridium(III) (abbreviated: Ir(dppm)2(acac)), or organometallic iridium complexes having a pyrazine backbone such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazineto)iridium(III) (abbreviated: Ir(mppr-Me)2(acac)) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazineto)iridium(III) (abbreviated: Ir(mppr-iPr)2(acac)), Tris(2-phenylpyridinato-N,C 2' )Iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinate-N,C 2' )Iridium(III)acetylacetonate (abbreviation: Ir(ppy)2(acac)), bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: Ir(bzq)2(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq)3), tris(2-phenylquinolinato-N,C 2' )Iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C 2' Organometallic iridium complexes having a pyridine backbone, such as iridium(III) acetylacetonate (abbreviated: Ir(pq)2(acac)), or bis(2,4-diphenyl-1,3-oxazolato-N,C 2' )Iridium(III)acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl)phenyl]pyridinate-N,C 2'}Iridium(III)acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolate-N,C 2'In addition to organometallic iridium complexes such as iridium(III) acetylacetonate (abbreviated: Ir(bt)2(acac)), rare earth metal complexes such as tris(acetylacetonate)(monophenanthrolin)terbium(III) (abbreviated: Tb(acac)3(Phen)) can be cited. Among those mentioned above, organometallic iridium complexes having a pyrimidine backbone are particularly desirable because they exhibit remarkably excellent reliability and luminescence efficiency.

[0144] In addition, as materials having a yellow or red emission peak, organometallic iridium complexes having a pyrimidine backbone, such as (diisobutyrylmetaneto)bis[4,6-bis(3-methylphenyl)pyrimidineto]iridium(III) (abbreviated: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidineto](dipivaloylmetaneto)iridium(III) (abbreviated: Ir(5mdppm)2(dpm)), and bis[4,6-di(naphthalene-1-yl)pyrimidineto](dipivaloylmetaneto)iridium(III) (abbreviated: Ir(d1npm)2(dpm)), are examples. Organometallic iridium complexes having a pyrazine backbone, such as (acetylacetonato)bis(2,3,5-triphenylpyrazineto)iridium(III) (abbreviated: Ir(tppr)2(acac)), bis(2,3,5-triphenylpyrazineto)(dipivaloylmetaneto)iridium(III) (abbreviated: Ir(tppr)2(dpm)), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviated: Ir(Fdpq)2(acac)), or tris(1-phenylisoquinolinato-N,C 2' )Iridium(III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinolinato-N,C 2'In addition to organometallic iridium complexes having a pyridine backbone such as iridium(III) acetylacetonate (abbreviated: Ir(piq)2(acac)), there are platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviated: PtOEP), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedioto)(monophenanthrolin)europium(III) (abbreviated: Eu(DBM)3(Phen)) and tris[1-(2-tenoyl)-3,3,3-trifluoroacetonato](monophenanthrolin)europium(III) (abbreviated: Eu(TTA)3(Phen)). Among those described above, organometallic iridium complexes having a pyrimidine framework are particularly desirable as they exhibit remarkably excellent reliability and luminescence efficiency. Additionally, organometallic iridium complexes having a pyrazine framework yield red luminescence with good color intensity.

[0145] As for the light-emitting material included in the light-emitting layer (130), it is preferable that the material be capable of converting triplet excited energy into light emission. In addition to phosphorescent compounds, materials capable of converting triplet excited energy into light emission may include thermally activated delayed fluorescence (TADF) materials. Therefore, the part described as phosphorescent compound may be read as thermally activated delayed fluorescence material. Furthermore, the thermally activated delayed fluorescence material is a material that has a small difference between the triplet excited energy level and the singlet excited energy level and has the function of converting energy from a triplet excited state to a singlet excited state through reverse conversion. Therefore, the triplet excited state can be up-converted to a singlet excited state by minute thermal energy, and light emission (fluorescence) from the singlet excited state can be efficiently displayed. In addition, conditions for efficiently obtaining thermally activated delayed fluorescence include the energy difference between the triplet excited energy level and the singlet excited energy level being preferably greater than 0 eV and less than or equal to 0.2 eV, and more preferably greater than 0 eV and less than or equal to 0.1 eV.

[0146] When the thermally activated delayed fluorescent material consists of one type of material, for example, the following materials may be used.

[0147] First, fullerenes or their derivatives, acridin derivatives such as proflavins, and eosin can be cited. In addition, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) can be cited. Examples of these metal-containing porphyrins include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), ethioporphyrin-tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc.

[0148] In addition, as a thermally activated delayed fluorescent material composed of one type of material, a complex ring compound having a π-electron excess hetero-directional ring and a π-electron deficiency complex-directional ring may be used. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindoleo[2,3-a]carbazole-11-yl)-1,3,5-triazine (abbreviated: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated: PCCzPTzn), 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated: PXZ-TRZ), and 3-[4-(5-phenyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazine (abbreviated: Examples include PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviated: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridin)phenyl]sulfone (abbreviated: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviated: ACRSA). The above complex ring compounds are desirable because they have a complex directional ring with an excess of π electrons and a complex directional ring with a deficiency of π electrons, and thus have high electron transport and hole transport. Among these, among the frameworks having a complex directional ring with a deficiency of π electrons, a diazine framework (pyrimidine framework, pyrazine framework, pyridazine framework) or a triazine framework is preferred because it is stable and reliable. In addition, among the frameworks having a complex directional ring with an excess of π electrons, the acridine framework, phenoxazine framework, thiophene framework, furan framework, and pyrrole framework are stable and reliable, so it is desirable to have one or more of the frameworks selected from the above. In addition, as for the pyrrole framework, the indole framework, carbazole framework, and 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole framework are particularly preferred.In addition, a material in which an electron-excess complex direction ring and an electron-deficient complex direction ring are directly bonded is particularly desirable because both the donor nature of the electron-excess complex direction ring and the acceptor nature of the electron-deficient complex direction ring are strong, and the difference between the energy levels of the singlet excited state and the triplet excited state becomes small.

[0149] Additionally, the light-emitting layer (130) may have materials other than the host material (131) and guest material (132).

[0150] There are no particular limitations on the materials that can be used for the light-emitting layer (130), but examples include condensed polycyclic aromatic compounds such as anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives. Specifically, 9,10-diphenylanthracene (abbreviated: DPAnth), 6,12-dimethoxy-5,11-diphenylchrysene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviated: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviated: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviated: t-BuDNA), 9,9'-bianthrile (abbreviated: BANT), and 9,9'-(stilbene-3,3'-diyl)diphenanthrene (abbreviated: Examples include DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviated: DPNS2), 1,3,5-tri(1-pyreneyl)benzene (abbreviated: TPB3), etc. Additionally, among these materials and known materials, it is preferable to select and use one or more types of materials having a singlet excited energy level or a triplet excited energy level higher than the excited energy level of the guest material (132).

[0151] In addition, compounds having a complex aromatic backbone, such as oxadiazole derivatives, can be used in the light-emitting layer (130). Specifically, examples include complex ring compounds such as 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviated: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-2-yl)phenyl]-9H-carbazole (abbreviated: CO11), and 4,4'-bis(5-methylbenzoxazole-2-yl)stilbene (abbreviated: BzOs).

[0152] In addition, metal complexes having complex rings (e.g., zinc and aluminum-based metal complexes) can be used in the light-emitting layer (130). Examples include metal complexes having quinoline ligands, benzoquinoline ligands, oxazole ligands, or thiazole ligands. Specifically, examples include metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as tris(8-quinolinoleto)aluminum(III) (abbreviated: Alq), tris(4-methyl-8-quinolinoleto)aluminum(III) (abbreviated: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviated: BeBq2), bis(2-methyl-8-quinolinoleto)(4-phenylphenolato)aluminum(III) (abbreviated: BAlq), and bis(8-quinolinoleto)zinc(II) (abbreviated: Znq). In addition, metal complexes having oxazole-based or thiazole-based ligands, such as bis[2-(2-benzoxazolyl)phenolate]zinc(II) (abbreviated: ZnPBO) and bis[2-(2-benzothiazolyl)phenolate]zinc(II) (abbreviated: ZnBTZ), can also be used.

[0153] Additionally, the light-emitting layer (130) may be composed of multiple layers, such as two or more layers. For example, when the first light-emitting layer and the second light-emitting layer are sequentially stacked from the hole transport layer side to form the light-emitting layer (130), a material having hole transport properties is used as the host material of the first light-emitting layer, and a material having electron transport properties is used as the host material of the second light-emitting layer. Furthermore, the light-emitting materials of the first light-emitting layer and the second light-emitting layer may be the same material or different materials, and may be materials having the function of emitting light of the same color or materials having the function of emitting light of different colors. By using light-emitting materials having the function of emitting light of different colors in each of the two light-emitting layers, multiple light emittings can be obtained simultaneously. In particular, it is desirable to select the light-emitting materials used in each light-emitting layer so that they become white due to the light emitting from the two light-emitting layers.

[0154] In addition, the light-emitting layer (130) can be formed by a deposition method (including vacuum deposition), an inkjet method, a coating method, gravure printing, etc. In addition to the materials described above, it may also have an inorganic compound such as a quantum dot or a polymer compound (oligomer, dendrimer, polymer, etc.).

[0155] <<Hole Injection Layer>>

[0156] The hole injection layer (111) has the function of promoting hole injection by reducing the barrier for hole injection from one of the pair of electrodes (electrode (101) or electrode (102)), and is formed of, for example, a transition metal oxide, a phthalocyanine derivative, an aromatic amine, a heteropoly acid, etc. that has electron accepting properties. Examples of transition metal oxides include titanium oxide, vanadium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, silver oxide, etc., and the above transition metal oxides are preferred because they have excellent electron accepting properties and can be easily formed by vacuum deposition or wet deposition. In addition, examples of phthalocyanine derivatives include phthalocyanine or metal phthalocyanine. Examples of aromatic amines include benzidine derivatives or phenylenediamine derivatives. Polymeric compounds such as polythiophene or polyaniline may be used; for example, poly(ethylenedioxythiophene) / poly(styrenesulfonic acid), which is a self-doped polythiophene, is a representative example. In addition, examples of heteropoly acids include phosphomolybdenum acid, phosphotungstic acid, silicon molybdenum acid, and silicon tungstic acid. Heteropoly acids or polymeric compounds are preferred because they can be easily formed into films by a wet method.

[0157] As a hole injection layer (111), it is preferable to use a layer having a composite material of a hole transport material with a low refractive index as described above and a material exhibiting electron acceptance as described above. By configuring it in this way, a layer with a low refractive index can be formed while having hole injection and hole transport properties. As an organic material having electron acceptance properties, TCNQ, F4TCNQ, and F6TCNNQ can be suitably used. In addition, a stacking of a layer containing a material exhibiting electron acceptance properties and a layer containing a hole transport material may be used. Charges can be exchanged between these materials in a steady state or in the presence of an electric field. As organic materials exhibiting electron acceptance properties, in addition to the TCNQ, F4TCNQ, and F6TCNNQ described above, organic acceptors such as quinodimethane derivatives, chloranyl derivatives, and hexa-azatriphenylene derivatives may be used. Specifically, it is a compound having an electron-withdrawing group (halogen group or cyano group), such as chloranyl or 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated: HAT-CN). In addition, transition metals, such as titanium, vanadium, tantalum, molybdenum, tungsten, rhenium, ruthenium, chromium, zirconium, hafnium, silver, etc., and materials containing oxygen may be used. Specifically, these include titanium oxide, vanadium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, silver oxide, phosphomolybdenum acid, molybdenum bronze, tungsten bronze, etc. Among these, molybdenum oxide is preferred because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

[0158] In addition, the hole-transporting material with a low refractive index used in the hole injection layer (111) can suitably be an organic compound having a structure in which the conjugate between aromatic rings is cut, represented by sp3 bonds, as described above, or an organic compound having an aromatic ring with a bulky substituent. Examples of frameworks having a structure in which the conjugate between aromatic rings is cut include the tetraarylmethane framework or the tetraarylsilane framework described above. However, on the other hand, such compounds tend to lack carrier transportability and are not suitable for conventional hole injection layers. Meanwhile, the material containing transition metals and oxygen as described above alone has a very high effect of increasing hole injectionability, but has the problem of a high refractive index. However, it was found that if the material containing transition metals and oxygen as described above is used in the hole injection layer (111) in combination with a hole-transporting material with a low refractive index as a material exhibiting electron acceptance, it is possible to secure hole injectionability and hole transportability while maintaining a low refractive index of the hole injection layer (111). In other words, this configuration can offset the disadvantages of both sides and manifest only the advantages. This is thought to be due to the high electron acceptance of materials containing transition metal oxides and the fact that hole injection capabilities can be secured with the addition of only a small amount.

[0159] As hole transport materials, materials with higher hole transport than electron transport can be used, and 1×10 -6 cm 2It is preferable that the material has a hole mobility of / Vs or higher. In addition, as described above, the hole transporting material preferably has a refractive index of 1 or higher and 1.75 or lower, more preferably 1 or higher and 1.73 or lower, and even more preferably 1 or higher and 1.70 or lower. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc., can be used as the hole transporting material for use in the light-emitting layer (130), but it is particularly preferable to have a complex aromatic framework having 1 to 20 carbon atoms containing two or more nitrogen atoms. In particular, a nitrogen-containing complex five-membered ring framework is preferred. In addition, the hole transporting material may be a polymer compound.

[0160] In addition, aromatic hydrocarbons can be cited as hole-transporting materials, such as 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviated: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviated: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviated: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviated: DNA), 9,10-diphenylanthracene (abbreviated: DPAnth), 2-tert-butylanthracene (abbreviated: t-BuAnth), and 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviated: DMNA). 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthrile, 10,10'-diphenyl-9,9'-bianthrile, 10,10'-bis(2-phenylphenyl)-9,9'-bianthrile, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthrile, anthracene, tetracene, rubrene, perylene, Examples include 2,5,8,11-tetra(tert-butyl)perylene. In addition, pentacene, coronene, etc., can also be used. Thus, 1×10 -6 cm 2 It is more preferable to use an aromatic hydrocarbon having 14 to 42 carbon atoms and a hole mobility of / Vs or higher.

[0161] In addition, aromatic hydrocarbons may have a vinyl backbone. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviated: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviated: DPVPA), etc.

[0162] Also, 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviated: mmDBFFLBi-II), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviated: DBF3P-II), 1,3,5-tri(dibenzothiophen-4-yl)benzene (abbreviated: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophen (abbreviated: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophen (abbreviated: DBTFLP-IV), Thiophene compounds such as 4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviated: mDBTPTp-II), furan compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds, etc., may be used. Among the compounds described above, compounds having a pyrrole backbone, a furan backbone, a thiophene backbone, or an aromatic amine backbone are preferred because they are stable and reliable. In addition, compounds having the above backbones have high hole transportability and contribute to reducing the driving voltage.

[0163] <<Precision Transport Layer>>

[0164] The hole transport layer (112) is a layer containing a hole transportable material, and the hole transportable material exemplified as the material of the hole injection layer (111) can be used. Since the hole transport layer (112) has the function of transporting holes injected into the hole injection layer (111) to the light-emitting layer (130), it is preferable that it has a HOMO (Highest Occupied Molecular Orbital, also called the highest occupied molecular orbital) level that is equal to or close to the HOMO level of the hole injection layer (111).

[0165] Also 1×10 -6 cm 2It is preferable that the material has a hole mobility of / Vs or higher. However, if the material has higher hole transportability than electron transportability, materials other than these may be used. In addition, the layer containing the material with high hole transportability may be a single layer, or two or more layers made of the above material may be stacked.

[0166] Electron Transport Layer

[0167] The electron transport layer (118) has the function of transporting electrons injected from the other side of a pair of electrodes (electrode (101) or electrode (102)) to the light-emitting layer (130) through the electron injection layer (119). As an electron transport material, a material with higher electron transportability than hole transportability can be used, and 1×10 -6 cm 2 It is preferable that the material has an electron mobility of / Vs or higher. As a compound that readily accepts electrons (a material having electron transport properties), π-electron deficient complex aromatic compounds such as nitrogen-containing complex aromatic compounds or metal complexes may be used. Specifically, examples of electron transport materials that can be used in the light-emitting layer (130) include pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, triazole derivatives, benzimidazole derivatives, oxadiazole derivatives, etc., but it is preferable that it has a complex aromatic backbone having 1 to 20 carbon atoms containing two or more nitrogen atoms. In particular, it is preferable that it is a compound having a pyrimidine backbone and a triazine backbone. Also, 1×10 -6 cm 2 It is preferable that the material has an electron mobility of / Vs or higher. Additionally, if the material has higher electron transportability than holes, other materials may be used as the electron transport layer (118). Furthermore, the electron transport layer (118) may be a single layer, or two or more layers made of the above material may be stacked.

[0168] In addition, metal complexes having a complex ring may be cited, for example, metal complexes having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand. Specifically, examples include metal complexes having a quinoline backbone or a benzoquinoline backbone, such as tris(8-quinolinoleto)aluminum(III) (abbreviated: Alq), tris(4-methyl-8-quinolinoleto)aluminum(III) (abbreviated: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviated: BeBq2), bis(2-methyl-8-quinolinoleto)(4-phenylphenolato)aluminum(III) (abbreviated: BAlq), and bis(8-quinolinoleto)zinc(II) (abbreviated: Znq). In addition, metal complexes having oxazole-based or thiazole-based ligands, such as bis[2-(2-benzoxazolyl)phenolate]zinc(II) (abbreviated: ZnPBO) and bis[2-(2-benzothiazolyl)phenolate]zinc(II) (abbreviated: ZnBTZ), can also be used.

[0169] In addition, a layer that controls the movement of electron carriers may be provided between the electron transport layer (118) and the light-emitting layer (130). This is a layer in which a small amount of a material with high electron trapping properties is added to the above-described material with high electron transportability, and the carrier balance can be controlled by suppressing the movement of electron carriers. Such a configuration is highly effective in suppressing problems (e.g., reduction in device lifespan) that occur when the electron transportability of the electron transportable material is very high compared to the hole transportability of the hole transportable material.

[0170] <<Electron Injection Layer>>

[0171] The electron injection layer (119) has the function of promoting electron injection by reducing the barrier to electron injection from the electrode (102), and may use, for example, Group 1 metals, Group 2 metals, or their oxides, halides, carbonates, etc. In addition, a composite material of the aforementioned electron transport material and a material exhibiting electron donating properties may be used. Examples of materials exhibiting electron donating properties include Group 1 metals, Group 2 metals, or their oxides. Specifically, lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2), and lithium oxide (LiO2) x Alkali metals, alkaline earth metals, or compounds thereof such as ) may be used. Additionally, rare earth metal compounds such as erbium fluoride (ErF3) may be used. Furthermore, an electride may be used in the electron injection layer (119). Examples of the electride include a material in which electrons are added at a high concentration to a mixed oxide of calcium and aluminum. Additionally, a material that can be used in the electron transport layer (118) may be used in the electron injection layer (119).

[0172] In addition, a composite material formed by mixing an organic compound and an electron donor (donor) may be used in the electron injection layer (119). Since electrons are generated in the organic compound by the electron donor, such a composite material has excellent electron injection and electron transport properties. In this case, it is desirable for the organic compound to be a material that is excellent for transporting the generated electrons, and specifically, for example, a material constituting the electron transport layer (118) described above (such as a metal complex or a complex aromatic compound) may be used. As for the electron donor, any material that exhibits electron-donating properties with respect to the organic compound is acceptable. Specifically, alkali metals, alkaline earth metals, or rare earth metals are preferred, and examples include lithium, sodium, cesium, magnesium, calcium, erbium, ytterbium, etc. Also, alkali metal oxides or alkaline earth metal oxides are preferred, and examples include lithium oxide, calcium oxide, barium oxide, etc. Additionally, Lewis bases such as magnesium oxide may be used. Also, organic compounds such as tetrathiafulvalene (abbreviated: TTF) may be used.

[0173] In addition, the aforementioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer can each be formed by a deposition method (including vacuum deposition), an inkjet method, a coating method, gravure printing, etc. In addition, in addition to the materials described above, inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymers, etc.) may be used for the aforementioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer.

[0174] <<Quantum Dot>>

[0175] Quantum dots are semiconductor nanocrystals with a size of several nanometers to tens of nanometers, and 1×10⁻⁶ 3 Pieces up to 1×10 6It is composed of about a few atoms. Since quantum dots shift energy depending on their size, even quantum dots made of the same material have different emission wavelengths depending on their size. Therefore, the emission wavelength can be easily changed by changing the size of the quantum dots used.

[0176] In addition, quantum dots can obtain luminescence with good color purity because the peak width of their emission spectrum is narrow. Furthermore, the theoretical internal quantum efficiency of quantum dots is known to be nearly 100%, which is significantly higher than the 25% of organic compounds exhibiting fluorescent luminescence and is equivalent to organic compounds exhibiting phosphorescent luminescence. Therefore, by using quantum dots as a light-emitting material, it is possible to obtain a light-emitting device with high luminous efficiency. In addition, since quantum dots are inorganic materials, they also have excellent intrinsic stability, so a desirable light-emitting device can be obtained in terms of lifespan.

[0177] Examples of materials constituting quantum dots include Group 14 elements, Group 15 elements, Group 16 elements, compounds composed of multiple Group 14 elements, compounds of elements belonging to Groups 4 to 14 and Group 16 elements, compounds of Group 2 elements and Group 16 elements, compounds of Group 13 elements and Group 15 elements, compounds of Group 13 elements and Group 17 elements, compounds of Group 14 elements and Group 15 elements, compounds of Group 11 elements and Group 17 elements, iron oxides, titanium oxides, chalcogenide spinels, semiconductor clusters, etc.

[0178] Specifically, cadmium selenide, cadmium sulfide, cadmium telluride, zinc selenide, zinc oxide, zinc sulfide, zinc telluride, mercury sulfide, mercury selenide, mercury telluride, indium arsenide, indium phosphide, gallium arsenide, gallium phosphide, indium nitride, gallium nitride, indium antimonide, gallium antimonide, aluminum phosphide, aluminum arsenide, aluminum antimonide, lead selenide, lead telluride, lead sulfide, indium selenide, indium telluride, indium sulfide, gallium selenide, arsenic sulfide, arsenic selenide, arsenic telluride, antimony sulfide, antimony selenide, antimony telluride, bismuth sulfide, bismuth selenide, bismuth telluride, silicon, silicon carbide, germanium, tin, Selenium, Tellurium, Boron, Carbon, Phosphorus, Boron Nitride, Boron Phosphate, Boron Arsenide, Aluminum Nitride, Aluminum Sulfide, Barium Sulfide, Barium Selenide, Barium Telluride, Calcium Sulfide, Calcium Selenide, Calcium Telluride, Beryllium Sulfide, Beryllium Selenide, Beryllium Telluride, Magnesium Sulfide, Magnesium Selenide, Germanium Sulfide, Germanium Selenide, Germanium Telluride, Tin Sulfide, Tin Selenide, Tin Telluride, Lead Oxide, Copper Fluoride, Copper Chloride, Copper Bromide, Copper Iodide, Copper Oxide, Copper Selenide, Nickel Oxide, Cobalt Oxide, Cobalt Sulfide, Iron Oxide, Iron Sulfide, Manganese Oxide, Molybdenum Sulfide, Vanadium Oxide, Tungsten Oxide, Tantalum Oxide, Titanium Oxide, Examples include zirconium oxide, silicon nitride, germanium nitride, aluminum oxide, barium titanate, compounds of selenium, zinc, and cadmium, compounds of indium, arsenic, and phosphorus, compounds of cadmium, selenium, and sulfur, compounds of cadmium, selenium, and tellurium, compounds of indium, gallium, and arsenic, compounds of indium, gallium, and selenium, compounds of indium, selenium, and sulfur, compounds of copper, indium, and sulfur, and combinations thereof, but are not limited thereto. In addition, so-called alloy-type quantum dots, in which the composition is expressed in any proportion, may be used.For example, cadmium, selenium, and sulfur alloy quantum dots are one of the effective means to obtain blue light emission because the wavelength of emission can be changed by changing the ratio of the elements.

[0179] Quantum dot structures include core-type, core-shell type, and core-multishell type, and any of these may be used. However, by covering the core and forming a shell with another inorganic material having a wider band gap, the influence of defects or dangling bonds present on the nanocrystal surface can be reduced. Since this significantly improves the quantum efficiency of luminescence, it is desirable to use core-shell type or core-multishell type quantum dots. Examples of shell materials include zinc sulfide or zinc oxide.

[0180] In addition, since quantum dots have a high proportion of surface atoms, they are highly reactive and prone to aggregation. Therefore, it is desirable to have a protective agent attached to the surface of the quantum dots or to have a protective group provided. If the protective agent is attached or a protective group is provided, aggregation can be prevented and the solubility of the solvent can be increased. Furthermore, electrical stability can be improved by reducing reactivity. As a protective agent (or protecting group), for example, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; trialkyl phosphines such as tripropyl phosphine, tributyl phosphine, trihexyl phosphine, and trioctyl phosphine; polyoxyethylene alkylphenyl ethers such as polyoxyethylene n-octylphenyl ether and polyoxyethylene n-nonylphenyl ether; tertiary amines such as tri(n-hexyl)amine, tri(n-octyl)amine, and tri(n-decyl)amine; organic phosphorus compounds such as tripropyl phosphine oxide, tributyl phosphine oxide, trihexyl phosphine oxide, trioctyl phosphine oxide, and tridecyl phosphine oxide; polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate; and also organic nitrogen compounds such as nitrogen-containing aromatic compounds such as pyridine, ruthidin, collidine, and quinoline, and hexylamine. Examples include aminoalkanes such as octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine; dialkyl sulfides such as dibutyl sulfide; dialkyl sulfoxides such as dimethyl sulfoxide and dibutyl sulfoxide; organic sulfur compounds such as sulfur-containing aromatic compounds such as thiophene; higher fatty acids such as palmitic acid, stearic acid, and oleic acid; alcohols; sorbitan fatty acid esters; fatty acid modified polyesters; tertiary amine modified polyurethanes; and polyethyleneimines.

[0181] Since the band gap of quantum dots increases as their size decreases, their size is appropriately adjusted to obtain light of a desired wavelength. As the crystal size decreases, the emission of quantum dots shifts toward the blue side, that is, toward high energy; therefore, by changing the size of the quantum dots, the emission wavelength can be adjusted across the wavelength ranges of the spectrum in the ultraviolet, visible, and infrared regions. The size (diameter) of the quantum dots is typically in the range of 0.5 nm to 20 nm, preferably 1 nm to 10 nm. Furthermore, the narrower the size distribution of the quantum dots, the more the emission spectrum becomes narrower, allowing for the attainment of emission with good color purity. Additionally, the shape of the quantum dots is not particularly limited and may be spherical, rod-shaped, disc-shaped, or other shapes. In addition, since quantum rods, which are rod-shaped quantum dots, have the function of exhibiting directional light, using quantum rods as a light-emitting material can obtain a light-emitting device with better external quantum efficiency.

[0182] However, in most organic EL devices, luminous efficiency is increased by dispersing the light-emitting material into a host material to suppress the concentration quenching of the light-emitting material. The host material must be a material having a singlet excited energy level or a triplet excited energy level greater than that of the light-emitting material. In particular, when using a blue phosphorescent material as the light-emitting material, it is extremely difficult to develop a host material that has a triplet excited energy level greater than that and is excellent in terms of lifetime. Here, since quantum dots can maintain luminous efficiency even when the light-emitting layer is composed solely of quantum dots without using a host material, a light-emitting device that is desirable in terms of lifetime can be obtained in this respect as well. When the light-emitting layer is formed solely of quantum dots, it is preferable that the quantum dots have a core-shell structure (including a core-multishell structure).

[0183] When quantum dots are used as the light-emitting material of the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of quantum dots in the light-emitting layer is 1 volume% to 100 volume%. However, it is preferable to form the light-emitting layer using only quantum dots. In addition, when forming a light-emitting layer in which the quantum dots are dispersed as a light-emitting material in a host, it is preferable to form the layer by dispersing the quantum dots in the host material, or by dissolving or dispersing the host material and the quantum dots in a suitable liquid medium using a wet process (spin coating, casting, die coating, blade coating, roll coating, inkjet, printing, spray coating, curtain coating, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum deposition method may also be preferably used.

[0184] As a liquid medium used in the wet process, for example, ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) may be used.

[0185] A pair of electrodes

[0186] The electrode (101) and the electrode (102) function as the positive or negative electrode of the light-emitting element. The electrode (101) and the electrode (102) can be formed using a metal, an alloy, a conductive compound, a mixture or laminate thereof, etc.

[0187] It is preferable that one of the electrode (101) and the electrode (102) be formed of a conductive material having the function of reflecting light. Examples of the conductive material include aluminum (Al) or an alloy containing Al. Examples of alloys containing Al include an alloy containing Al and L (where L represents one or more of titanium (Ti), neodymium (Nd), nickel (Ni), and lanthanum (La)), and examples include an alloy containing Al and Ti, or Al, Ni, and La. Aluminum has a low resistance value and a high light reflectivity. In addition, since aluminum is abundant in the Earth's crust and inexpensive, the manufacturing cost of the light-emitting device can be reduced by using aluminum. In addition, silver (Ag) or alloys containing Ag and N (N refers to one or a plurality of yttrium (Y), Nd, magnesium (Mg), ytterbium (Yb), Al, Ti, gallium (Ga), zinc (Zn), indium (In), tungsten (W), manganese (Mn), tin (Sn), iron (Fe), Ni, copper (Cu), palladium (Pd), iridium (Ir), and gold (Au)) may be used. Examples of alloys containing silver include alloys containing silver, palladium, and copper; alloys containing silver and copper; alloys containing silver and magnesium; alloys containing silver and nickel; alloys containing silver and gold; and alloys containing silver and ytterbium. In addition, transition metals such as tungsten, chromium (Cr), molybdenum (Mo), copper, and titanium may be used.

[0188] In addition, the light emitted from the light-emitting layer is extracted through one or both of the electrode (101) and the electrode (102). Accordingly, it is preferable that at least one of the electrode (101) and the electrode (102) be formed of a conductive material having the function of transmitting light. The conductive material has a transmittance of visible light of 40% or more and 100% or less, preferably 60% or more and 100% or less, and also has a resistivity of 1×10⁻⁶ -2Examples of conductive materials with a conductivity of Ω·cm or less include.

[0189] Additionally, the electrode (101) and the electrode (102) may be formed of a conductive material having the function of transmitting light and reflecting light. The conductive material has a reflectance of visible light of 20% or more and 80% or less, preferably 40% or more and 70% or less, and also has a resistivity of 1×10⁻⁶ -2 Examples of conductive materials with a conductivity of Ω·cm or less may be used. For instance, one or more types of conductive metals, alloys, or conductive compounds may be used. Specifically, metal oxides such as indium tin oxide (hereinafter ITO), indium tin oxide containing silicon or silicon oxide (abbreviated as ITSO), indium zinc oxide, indium tin oxide containing titanium, indium titanium oxide, and indium oxide containing tungsten oxide and zinc oxide may be used. Additionally, a metal thin film with a thickness sufficient to transmit light (preferably 1 nm or more and 30 nm or less) may be used. As for the metal, examples include Ag, or alloys such as Ag and Al, Ag and Mg, Ag and Au, and Ag and Yb.

[0190] In addition, the material having the function of transmitting light in this specification and the like is preferably a material having the function of transmitting visible light and also having conductivity. For example, in addition to oxide conductors represented by ITO as described above, it includes oxide semiconductors or organic conductors containing organic materials. Examples of organic conductors containing organic materials include composite materials formed by mixing an organic compound and an electron donor, and composite materials formed by mixing an organic compound and an electron acceptor. In addition, inorganic carbon-based materials such as graphene may be used. Furthermore, the resistivity of the above material is preferably 1×10⁻⁶ 5Ω·cm or less, more preferably 1×10⁻⁶ 4 It is less than Ω·cm.

[0191] In addition, one or both of the electrode (101) and the electrode (102) may be formed by stacking multiple layers of the above-described material.

[0192] In addition, to improve light extraction efficiency, a material with a higher refractive index than the electrode may be formed in contact with an electrode having a light-transmitting function. Such a material may be a material having a function of transmitting visible light, and may be a material having conductivity or a material not having conductivity. For example, in addition to the oxide conductor described above, oxide semiconductors or organic materials may be used. As for organic materials, examples include the materials exemplified in the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, or electron injection layer. In addition, inorganic carbon-based materials or metal thin films capable of transmitting light may be used, and multiple layers of several nanometers to tens of nanometers may be stacked.

[0193] When the electrode (101) or electrode (102) functions as a negative electrode, it is preferable to have a material with a small work function (3.8 eV or less). For example, elements belonging to Group 1 or Group 2 of the periodic table of elements (alkali metals such as lithium, sodium, cesium, etc., alkaline earth metals such as calcium, strontium, etc., magnesium, etc.), alloys containing these elements (e.g., Ag and Mg, Al and Li), rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. may be used.

[0194] In addition, when using the electrode (101) or electrode (102) as an anode, it is preferable to use a material with a large work function (4.0 eV or more).

[0195] Additionally, the electrode (101) and the electrode (102) may be a laminate of a conductive material having a function of reflecting light and a conductive material having a function of transmitting light. In this case, the electrode (101) and the electrode (102) are preferred because they may have a function of adjusting the optical distance so as to resonate light of a desired wavelength from each light-emitting layer to strengthen the light of a desired wavelength.

[0196] The film formation method of the electrode (101) and electrode (102) can appropriately use sputtering, deposition, printing, coating, MBE (Molecular Beam Epitaxy) method, CVD method, pulsed laser deposition method, ALD (Atomic Layer Deposition) method, etc.

[0197] <<Circuit Board>>

[0198] In addition, a light-emitting element according to one embodiment of the present invention may be fabricated on a substrate made of glass, plastic, etc. The order of fabrication on the substrate may be sequential stacking from the electrode (101) side or sequential stacking from the electrode (102) side.

[0199] In addition, for a substrate capable of forming a light-emitting element according to one embodiment of the present invention, glass, quartz, or plastic may be used. A flexible substrate may also be used. A flexible substrate refers to a substrate that can be bent (flexible), and examples include plastic substrates made of polycarbonate or polyarylate. In addition, a film or an inorganic deposition film may be used. Furthermore, materials other than these may be used if they function as a support in the fabrication process of the light-emitting element and the optical element. Alternatively, it is acceptable if they have a function of protecting the light-emitting element and the optical element.

[0200] For example, in the present invention, a light-emitting element can be formed using various substrates. The type of substrate is not particularly limited. Examples of such substrates include semiconductor substrates (e.g., single-crystal substrates or silicon substrates), SOI substrates, glass substrates, quartz substrates, plastic substrates, metal substrates, stainless steel substrates, substrates having stainless steel foil, tungsten substrates, substrates having tungsten foil, flexible substrates, bonding films, paper containing fibrous materials, or base films. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, or soda-lime glass. Examples of flexible substrates, bonding films, base films, etc. include the following. For example, there are plastics represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Or, for example, there are resins such as acrylic. Or, examples include polypropylene, polyester, polyfluorinated vinyl, or polyvinyl chloride. Or, examples include polyamide, polyimide, aramid, epoxy, inorganic deposited film, or paper products.

[0201] In addition, a flexible substrate may be used as the substrate, and a light-emitting element may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light-emitting element. The release layer can be used to separate the light-emitting element from the substrate and transfer it to another substrate after completing part or all of the light-emitting element thereon. At this time, the light-emitting element can be transferred even on a substrate with poor heat resistance or a flexible substrate. Furthermore, the above-described release layer may use, for example, a configuration in which an inorganic film such as a tungsten film and a silicon oxide film are laminated, or a configuration in which a resin film such as polyimide is formed on the substrate.

[0202] That is, a light-emitting element may be formed using a substrate, and then the light-emitting element may be transferred to another substrate and placed on the other substrate. Examples of substrates on which the light-emitting element is transferred include, in addition to the substrates described above, cellophane substrates, stone substrates, wood substrates, fabric substrates (including natural fibers (silk, cotton, hemp), synthetic fibers (nylon, polyurethane, polyester), or recycled fibers (acetate, cupro, rayon, recycled polyester), leather substrates, or rubber substrates. By using these substrates, it is possible to make a light-emitting element that is resistant to breakage, a light-emitting element with high heat resistance, a lightweight light-emitting element, or a thin light-emitting element.

[0203] In addition, for example, a field-effect transistor (FET) may be formed on the substrate described above, and a light-emitting element (150) may be fabricated on an electrode electrically connected to the FET. Accordingly, an active matrix type display device can be fabricated that controls the driving of the light-emitting element (150) by the FET.

[0204] A component of a solar cell, which is an example of an electronic device according to one embodiment of the present invention, is described below.

[0205] Materials that can be used for the light-emitting device described above may be utilized in the solar cell. The hole-transporting material and electron-transporting material described above may be used for the carrier transport layer of the solar cell, and the hole-transporting material and electron-transporting material described above, the light-emitting material, silicon, or perovskite crystals represented by CH3NH3PbI3 may be used as the photovoltaic layer. Furthermore, regarding the substrate and electrode, materials that can be used for the light-emitting device described above may also be utilized.

[0206] The configurations shown in the above embodiments can be used in appropriate combination with other embodiments.

[0207] (Embodiment 2)

[0208] In this embodiment, a light-emitting element with a configuration different from that of the light-emitting element shown in Embodiment 1, and a light-emitting mechanism of said light-emitting element, will be described below using FIGS. 3 and 4. In FIGS. 3 and 4, locations having the same function as the symbol shown in (A) of FIG. 2 may have the same hatch pattern and the symbol may be omitted. Also, locations having the same function may have the same symbol attached and the detailed description thereof omitted.

[0209] <Composition Example 1 of a Light-Emitting Element>

[0210] Figure 3 (A) is a schematic cross-sectional view of a light-emitting element (250).

[0211] The light-emitting element (250) illustrated in FIG. 3 (A) has a plurality of light-emitting units (in FIG. 3 (A), light-emitting units (106) and light-emitting units (108)) between a pair of electrodes (electrode (101) and electrode (102)). Additionally, although the electrode (101) functions as an anode and the electrode (102) functions as a cathode in the light-emitting element (250), the configuration of the light-emitting element (250) may be reversed.

[0212] In addition, in the light-emitting element (250) illustrated in (A) of FIG. 3, a light-emitting unit (106) and a light-emitting unit (108) are stacked, and a charge generating layer (115) is provided between the light-emitting unit (106) and the light-emitting unit (108). In addition, the light-emitting unit (106) and the light-emitting unit (108) may have the same configuration or different configurations.

[0213] Additionally, the light-emitting element (250) has a light-emitting layer (120) and a light-emitting layer (170). Additionally, the light-emitting unit (106) has a hole injection layer (111), a hole transport layer (112), an electron transport layer (113), and an electron injection layer (114) in addition to the light-emitting layer (170). Additionally, the light-emitting unit (108) has a hole injection layer (116), a hole transport layer (117), an electron transport layer (118), and an electron injection layer (119) in addition to the light-emitting layer (120).

[0214] The charge generating layer (115) may be composed of an acceptor material that is an electron acceptor added to a hole-transporting material, or a donor material that is an electron donor added to an electron-transporting material. Additionally, both of these compositions may be stacked.

[0215] When a composite material of an organic compound and an acceptor material is included in the charge generation layer (115), the composite material may be a composite material that can be used in the hole injection layer (111) shown in Embodiment 1. As the organic compound, various compounds may be used, such as aromatic amine compounds, carbazole compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.). In addition, as the organic compound, a hole mobility of 1×10 -6 cm 2It is preferable to apply a material with a value of / Vs or higher. However, if the material has higher hole transportability than electron transportability, other materials may be used. Since composite materials of organic compounds and acceptor materials have excellent carrier injection and carrier transportability, low-voltage driving and low-current driving can be realized. Furthermore, when the positive side of the light-emitting unit is in contact with the charge generation layer (115), the charge generation layer (115) can also function as a hole injection layer or hole transport layer of the light-emitting unit, so the light-emitting unit may be configured without providing a hole injection layer or a hole transport layer. Alternatively, when the negative side of the light-emitting unit is in contact with the charge generation layer (115), the charge generation layer (115) can also function as an electron injection layer or electron transport layer of the light-emitting unit, so the light-emitting unit may be configured without providing an electron injection layer or an electron transport layer.

[0216] Additionally, the charge generating layer (115) may be formed as a laminated structure comprising a layer containing a composite material of an organic compound and an acceptor material 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 an acceptor material with a layer containing one selected from electron-donating materials and a compound with high electron transportability. Additionally, it may be formed by combining a layer containing a composite material of an organic compound and an acceptor material with a layer containing a transparent conductive film.

[0217] Additionally, the charge generation layer (115) sandwiched between the light-emitting unit (106) and the light-emitting unit (108) is preferably configured to inject electrons into one light-emitting unit and inject holes into the other light-emitting unit when a voltage is applied to the electrode (101) and the electrode (102). For example, in (A) of FIG. 3, when a voltage is applied such that the potential of the electrode (101) becomes higher than the potential of the electrode (102), the charge generation layer (115) injects electrons into the light-emitting unit (106) and injects holes into the light-emitting unit (108).

[0218] In addition, the charge generating layer (115) is preferably transparent to visible light (specifically, the transmittance of visible light to the charge generating layer (115) is 40% or more) in terms of light extraction efficiency. In addition, the charge generating layer (115) functions even if it has a lower conductivity than a pair of electrodes (electrode (101) and electrode (102)).

[0219] By forming a charge generation layer (115) using the above-described material, the increase in driving voltage in the case where the light-emitting layer is stacked can be suppressed.

[0220] In addition, although (A) of FIG. 3 describes a light-emitting device having two light-emitting units, the same can be applied to a light-emitting device having three or more light-emitting units stacked. As shown in the light-emitting device (250), by arranging a plurality of light-emitting units in a charge-generating layer between a pair of electrodes, it is possible to achieve high-brightness light emission while maintaining a low current density, and to realize a light-emitting device with a longer lifespan. In addition, it is possible to realize a light-emitting device with low power consumption.

[0221] In addition, regarding the light emission color exhibited by the guest material used in the light-emitting unit (106) and the light-emitting unit (108) in each of the above configurations, they may be the same or different. If the light-emitting unit (106) and the light-emitting unit (108) have a guest material having the function of exhibiting light emission of the same color, the light-emitting element (250) is preferably a light-emitting element that exhibits high light emission brightness with a low current value. In addition, if the light-emitting unit (106) and the light-emitting unit (108) have a guest material having the function of exhibiting light emission of different colors, the light-emitting element (250) is preferably a light-emitting element that exhibits multi-color light emission. In this case, by using a plurality of light-emitting materials with different light emission wavelengths in either or both of the light-emitting layer (120) and the light-emitting layer (170), the light emission spectrum exhibited by the light-emitting element (250) becomes light that is a composite of light emission having different light emission peaks, and thus becomes a light emission spectrum having at least two maximum values.

[0222] The above configuration is also suitable for obtaining white light emission. White light emission can be obtained by making the light from the light-emitting layer (120) and the light-emitting layer (170) complementary to each other. In particular, it is desirable to select a guest material so as to produce white light emission with high color rendering or at least light emission having red, green, and blue.

[0223] In addition, in the case of a light-emitting device comprising three or more stacked light-emitting units, the light-emitting colors exhibited by the guest materials used in each light-emitting unit may be the same or different. When there are multiple light-emitting units that emit the same color, the light-emitting colors exhibited by these multiple units can obtain high luminous brightness with a small current value compared to other colors. Such a configuration is suitable for use in adjusting the light-emitting color. In particular, it is suitable when using guest materials that have different luminous efficiencies and exhibit different light-emitting colors. For example, in the case of having three layers of light-emitting units, the light-emitting intensity of fluorescent light emission and phosphorescent light emission can be adjusted by having two layers of light-emitting units having fluorescent materials of the same color and one layer of light-emitting units having phosphorescent materials that exhibit a light-emitting color different from the fluorescent materials. That is, the intensity of the light-emitting color can be adjusted according to the number of light-emitting units.

[0224] In the case of a light-emitting device having two layers of such fluorescent light-emitting units and one layer of phosphorescent light-emitting units, it is preferable to have a light-emitting device having two layers of light-emitting units containing blue fluorescent material and one layer of light-emitting units containing yellow phosphorescent material, a light-emitting device having two layers of light-emitting units containing blue fluorescent material and one layer of light-emitting unit containing red phosphorescent material and green phosphorescent material, or a light-emitting device having two layers of light-emitting units containing blue fluorescent material and one layer of light-emitting unit containing red phosphorescent material, yellow phosphorescent material, and green phosphorescent material, because white light emission is efficiently obtained.

[0225] Additionally, at least one of the light-emitting layer (120) and the light-emitting layer (170) may be further divided into layers, and each divided layer may include a different light-emitting material. That is, at least one of the light-emitting layer (120) and the light-emitting layer (170) may be composed of two or more layers. For example, when the first light-emitting layer and the second light-emitting layer are sequentially stacked from the hole transport layer side to form a light-emitting layer, there is a configuration in which a material having hole transport properties is used as the host material of the first light-emitting layer, and a material having electron transport properties is used as the host material of the second light-emitting layer. In this case, the light-emitting materials of the first light-emitting layer and the second light-emitting layer may be the same material or different materials, and may be materials having the function of emitting light of the same color or materials having the function of emitting light of different colors. By a configuration having multiple light-emitting materials having the function of emitting light of different colors, white light with high color rendering, consisting of three primary colors or four or more light-emitting colors, may be obtained.

[0226] In addition, by applying the configuration shown in Embodiment 1 to at least one of the multiple units, a light-emitting element with good light extraction efficiency and reduced driving voltage can be provided.

[0227] Additionally, the light-emitting layer (120) of the light-emitting unit (108) has a guest material (121) and a host material (122) as shown in (B) of FIG. 3. Additionally, the guest material (121) is a fluorescent material and will be described below.

[0228] <<Light-emitting mechanism of the light-emitting layer (120)>>

[0229] The light-emitting mechanism of the light-emitting layer (120) is described below.

[0230] Excitons are generated by electrons and holes injected from a pair of electrodes (electrode (101) and electrode (102)) or a charge generation layer (115) recombining in the light-emitting layer (120). Since the host material (122) is present in large quantities compared to the guest material (121), the generation of excitons forms an excited state of almost the host material (122). Additionally, an exciton refers to a pair of carriers (electron and hole).

[0231] When the excited state of the formed host material (122) is a single excited state, the single excited energy is transferred from the S1 level of the host material (122) to the S1 level of the guest material (121), thereby forming a single excited state of the guest material (121).

[0232] Since the guest material (121) is a fluorescent material, when a singlet excited state is formed in the guest material (121), the guest material (121) emits light rapidly. At this time, in order to obtain high luminescence efficiency, it is desirable for the fluorescence quantum yield of the guest material (121) to be high. In addition, the same applies when the excited state generated by the carrier recombination in the guest material (121) is a singlet excited state.

[0233] Next, the case in which a triplet excited state of the host material (122) is formed by carrier recombination is described. The correlation between the energy levels of the host material (122) and the guest material (121) in this case is shown in FIG. 3 (C). In addition, the notations and symbols in FIG. 3 (C) are as follows. Also, since it is preferable that the T1 level of the host material (122) be lower than the T1 level of the guest material (121), FIG. 3 (C) illustrates this case, but the T1 level of the host material (122) may be higher than the T1 level of the guest material (121).

[0234] · Guest(121): Guest material(121)(fluorescent material)

[0235] · Host(122): Host material(122)

[0236] · S FG : S1 level of guest material (121) (fluorescent material)

[0237] · T FG : T1 level of guest material (121) (fluorescent material)

[0238] · S FH : S1 level of host material (122)

[0239] · T FH : T1 level of host material (122)

[0240] As shown in (C) of FIG. 3, triplet excitons generated by carrier recombination through triplet-triplet annihilation (TTA) interact to exchange excited energies with one another and perform an exchange of spin angular momentum, resulting in the S1 level (S1) of the host material (122). FH A reaction occurs in which it is converted into a singlet exciton having the energy of (see TTA in (C) of FIG. 3). The singlet excited energy of the host material (122) is S FH From, the S1 level (S of guest material (121) with lower energy than that. FG Energy transfer occurs (see path (E1) of (C) in Fig. 3), and a single excited state of the guest material (121) is formed, causing the guest material (121) to emit light.

[0241] In addition, when the density of triplet excitons in the light-emitting layer (120) is sufficiently high (e.g., 1×10⁻⁶ 12 cm -3 In the above, we can ignore the inactivation of a single triplet exciton and consider only the reaction by two adjacent triplet excitons.

[0242] Additionally, when carriers recombine in the guest material (121) to form a triplet excited state, the triplet excited state of the guest material (121) becomes difficult to use for luminescence because it is thermally deactivated. However, the T1 level (T FH ) is the T1 level (T of guest material (121) FG When lower than ), the triplet excited energy of the guest material (121) is the T1 level (T FG The T1 level (T) of the host material (122) from ) FH Energy can be transferred to (see path (E2) in (C) of Fig. 3), and then used for TTA.

[0243] That is, it is desirable for the host material (122) to have the function of converting triplet excited energy into singlet excited energy by TTA. By doing so, a portion of the triplet excited energy generated in the light-emitting layer (120) can be converted into singlet excited energy by TTA in the host material (122), and the singlet excited energy can be transferred to the guest material (121) to be extracted as fluorescent light emission. To do this, the S1 level (S1) of the host material (122) FH ) is the S1 level (S of guest material (121) FG It is desirable that it be higher than ). Also, the T1 level (T FH ) is the T1 level (T of guest material (121) FG It is desirable that it be lower than ).

[0244] In addition, in particular, the T1 level (T FG ) is the T1 level (T FHIn cases lower than ), it is preferable that the weight ratio of the guest material (121) to the host material (122) has a lower weight ratio of the guest material (121). Specifically, when the host material (122) is set to 1, the weight ratio of the guest material (121) is preferably greater than 0 and less than or equal to 0.05. By doing so, the probability of carrier recombination in the guest material (121) can be reduced. Additionally, the T1 level (T FH The T1 level (T) of the guest material (121) from ) FG It can reduce the probability of energy transfer to ).

[0245] Additionally, the host material (122) may be composed of a single compound or may be composed of multiple compounds.

[0246] In addition, when the guest materials having different light emission colors in the light-emitting unit (106) and the light-emitting unit (108) are configured such that the light emission from the light-emitting layer (120) has a peak of light emission on the shorter wavelength side than the light emission from the light-emitting layer (170). A light-emitting device using a material having a high triplet excited energy level tends to have rapid brightness degradation. Therefore, by using TTA in the light-emitting layer that exhibits short-wavelength light emission, a light-emitting device with low brightness degradation can be provided.

[0247] <Composition Example of Light-emitting Element 2>

[0248] Figure 4 (A) is a schematic cross-sectional view of a light-emitting element (252).

[0249] The light-emitting element (252) illustrated in FIG. 4 (A) has a plurality of light-emitting units (in FIG. 4 (A), light-emitting unit (106) and light-emitting unit (110)) between a pair of electrodes (electrode (101) and electrode (102)), similar to the light-emitting element (250) described above. At least one light-emitting unit has a configuration similar to that of the EL layer (100). Additionally, the light-emitting unit (106) and the light-emitting unit (110) may have the same configuration or different configurations.

[0250] Additionally, in the light-emitting element (252) illustrated in (A) of FIG. 4, a light-emitting unit (106) and a light-emitting unit (110) are stacked, and a charge-generating layer (115) is provided between the light-emitting unit (106) and the light-emitting unit (110). For example, it is preferable to use an EL layer (100) in the light-emitting unit (106).

[0251] Additionally, the light-emitting element (252) has a light-emitting layer (140) and a light-emitting layer (170). Additionally, the light-emitting unit (106) has a hole injection layer (111), a hole transport layer (112), an electron transport layer (113), and an electron injection layer (114) in addition to the light-emitting layer (170). Additionally, the light-emitting unit (110) has a hole injection layer (116), a hole transport layer (117), an electron transport layer (118), and an electron injection layer (119) in addition to the light-emitting layer (140).

[0252] In addition, by applying the configuration shown in Embodiment 1 to at least one of the multiple units, a light-emitting element with good light extraction efficiency and reduced driving voltage can be provided.

[0253] The light-emitting layer (140) of the light-emitting unit (110) has a guest material (141) and a host material (142) as shown in (B) of FIG. 4. Additionally, the host material (142) has an organic compound (142_1) and an organic compound (142_2). Furthermore, the guest material (141) of the light-emitting layer (140) is described below as a phosphorescent material.

[0254] <<Light-emitting mechanism of the light-emitting layer (140)>>

[0255] Next, the light-emitting mechanism of the light-emitting layer (140) will be explained below.

[0256] The organic compound (142_1) and the organic compound (142_2) of the light-emitting layer (140) form an excited complex.

[0257] The combination of organic compound (142_1) and organic compound (142_2) is preferably one that can form a complex that is excited to one another, but it is more preferable that one is a compound with hole transport properties and the other is a compound with electron transport properties.

[0258] The correlation of energy levels of the organic compound (142_1), the organic compound (142_2), and the guest material (141) in the light-emitting layer (140) is shown in (C) of FIG. 4. In addition, the notations and symbols in (C) of FIG. 4 are as follows.

[0259] · Guest(141): Guest material(141)(phosphorescent material)

[0260] · Host(142_1): Organic compound(142_1)(host material)

[0261] · Host(142_2): Organic compound(142_2)(Host material)

[0262] · T PG : T1 level of guest material (141) (phosphorescent material)

[0263] · S PH1 : S1 level of organic compound (142_1) (host material)

[0264] · T PH1 : T1 level of organic compound (142_1) (host material)

[0265] · S PH2 : S1 level of organic compound (142_2) (host material)

[0266] · T PH2 : T1 level of organic compound (142_2) (host material)

[0267] · S PE : S1 level of the excited complex

[0268] · T PE : T1 level of the excited complex

[0269] The organic compound (142_1) and the organic compound (142_2) form an excited complex, and the S1 level (S of the excited complex) PE ) and T1 level (T PE ) becomes adjacent energies (see path (E3) in (C) of Fig. 4).

[0270] Organic compounds (142_1) and organic compounds (142_2) rapidly form an excited complex by one side receiving a hole and the other side receiving an electron. Alternatively, when one side becomes excited, it rapidly interacts with the other side to form an excited complex. Thus, most of the excitons in the light-emitting layer (140) exist as excited complexes. The excited energy level (S) of the excited complex PE or T PE ) is the S1 level (S) of the host material (organic compound (142_1) and organic compound (142_2)) forming the excited complex. PH1 and S PH2 Since it becomes lower than ), the excited state of the host material (142) can be formed at a lower excited energy. By doing so, the driving voltage of the light-emitting element can be lowered.

[0271] And, S of the excited complex PE Wow T PE The energy from both sides is transferred to the T1 level of the guest material (141) (phosphorescent material) to obtain luminescence (see path (E4) and path (E5) in (C) of FIG. 4).

[0272] Also, the T1 level (T PE ) is the T1 level (T PGIt is desirable that it be greater than ). By doing so, the singlet excited energy and triplet excited energy of the generated excited complex are the S1 level (S of the excited complex). PE ) and T1 level (T PE The T1 level (T) of the guest material (141) from ) PG Energy can be transferred to ).

[0273] In addition, in order to efficiently transfer excited energy from the excited complex to the guest material (141), the T1 level (T PE The T1 level (T) of each organic compound (organic compound (142_1) and organic compound (142_2)) that forms the excited complex PH1 and T PH2 It is desirable that it be equal to or smaller than ). By doing so, it becomes difficult for the triplet excited energy of the excited complex to quench due to each organic compound (organic compound (142_1) and organic compound (142_2)), so that energy transfer from the excited complex to the guest material (141) occurs efficiently.

[0274] In addition, for organic compounds (142_1) and organic compounds (142_2) to efficiently form an excited complex, it is desirable that the HOMO level of one of the organic compounds (142_1) and organic compounds (142_2) is higher than the HOMO level of the other, and the LUMO level of one is higher than the LUMO level of the other. For example, when organic compounds (142_1) have hole transport and organic compounds (142_2) have electron transport, it is desirable that the HOMO level of organic compounds (142_1) is higher than the HOMO level of organic compounds (142_2), and it is desirable that the LUMO level of organic compounds (142_1) is higher than the LUMO level of organic compounds (142_2). Alternatively, when the organic compound (142_2) has hole transport and the organic compound (142_1) has electron transport, it is preferable that the HOMO level of the organic compound (142_2) is higher than the HOMO level of the organic compound (142_1), and it is preferable that the LUMO level of the organic compound (142_2) is higher than the LUMO level of the organic compound (142_1). Specifically, the energy difference between the HOMO level of the organic compound (142_1) and the HOMO level of the organic compound (142_2) is preferably 0.05 eV or more, more preferably 0.1 eV or more, and even more preferably 0.2 eV or more. In addition, the energy difference between the LUMO level of the organic compound (142_1) and the LUMO level of the organic compound (142_2) is preferably 0.05 eV or more, more preferably 0.1 eV or more, and even more preferably 0.2 eV or more.

[0275] In addition, when the combination of the organic compound (142_1) and the organic compound (142_2) is a combination of a compound having hole transport and a compound having electron transport, the carrier balance can be easily controlled according to the mixing ratio. Specifically, it is preferable that the ratio of the compound having hole transport to the compound having electron transport be in the range of 1:9 to 9:1 (weight ratio). In addition, by having this configuration, the carrier balance can be easily controlled, and thus the control of the carrier recombination region can also be easily performed.

[0276] By configuring the light-emitting layer (140) as described above, light emission from the guest material (141) (phosphorescent material) of the light-emitting layer (140) can be efficiently obtained.

[0277] Additionally, the process of the path (E3) to path (E5) described above may be referred to as ExTET (Exciplex-Triplet Energy Transfer) in this specification, etc. In other words, the light-emitting layer (140) has the donation of excited energy from the excited composite to the guest material (141). Also, in this case, T PE From S PE The cross-terminal efficiency of the row does not necessarily need to be high, and S PE Since there is no need for the emission quantum yield from to be high, a wide range of materials can be selected.

[0278] In addition, it is preferable to configure the light emission from the light emission layer (170) to have a peak of light emission on the shorter wavelength side than the light emission from the light emission layer (140). Light-emitting devices using phosphorescent materials that emit light at short wavelengths tend to experience rapid brightness degradation. Therefore, by making the short-wavelength light emission fluorescent light emission, a light-emitting device with low brightness degradation can be provided.

[0279] Examples of materials that can be used in the light-emitting layer

[0280] Next, materials that can be used for the light-emitting layer (120), the light-emitting layer (140), and the light-emitting layer (170) will be described below.

[0281] <<Materials that can be used for the light-emitting layer (120)>>

[0282] In the light-emitting layer (120), the host material (122) is present in the largest weight ratio, and the guest material (121) (fluorescent material) is dispersed within the host material (122). It is preferable that the S1 level of the host material (122) is higher than the S1 level of the guest material (121) (fluorescent material), and that the T1 level of the host material (122) is lower than the T1 level of the guest material (121) (fluorescent material).

[0283] In the light-emitting layer (120), there are no particular limitations on the guest material (121), but anthracene derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, phenothiazine derivatives, etc. are preferred, and the fluorescent compound shown in Example 1 can be suitably used.

[0284] Additionally, regarding the light-emitting layer (120), there are no particular limitations on the materials that can be used as the host material (122), but for example, tris(8-quinolinoleto)aluminum(III) (abbreviated: Alq), tris(4-methyl-8-quinolinoleto)aluminum(III) (abbreviated: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviated: BeBq2), bis(2-methyl-8-quinolinoleto)(4-phenylphenolate)aluminum(III) (abbreviated: BAlq), bis(8-quinolinoleto)zinc(II) (abbreviated: Znq), bis[2-(2-benzoxazolyl)phenolate]zinc(II) (abbreviated: ZnPBO), Metal complexes such as bis[2-(2-benzothiazolyl)phenolate]zinc(II) (abbreviation: ZnBTZ), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviation: OXD-7), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), vasofenanthroline (abbreviation: BPhen), Examples include heterocyclic compounds such as vasocuproin (abbreviated: BCP) and 9-[4-(5-phenyl-1,3,4-oxadiazole-2-yl)phenyl]-9H-carbazole (abbreviated: CO11), aromatic amine compounds such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated: TPD), and 4,4'-bis[N-(spiro-9,9'-bifluorene-2-yl)-N-phenylamino]biphenyl (abbreviated: BSPB).In addition, condensed polycyclic aromatic compounds such as anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives can be cited, specifically, 9,10-diphenylanthracene (abbreviated: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviated: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviated: DPhPA), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviated: YGAPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviated: PCAPA), N,9-Diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazole-3-amine (abbreviation: PCAPBA), N,9-Diphenyl-N-(9,10-Diphenyl-2-anthryl)-9H-carbazole-3-amine (abbreviation: 2PCAPA), 6,12-Dimethoxy-5,11-Diphenylchrycene, N,N,N',N',N'',N'',N''',N'''-OctaphenylDibenzo[g,p]chrycene-2,7,10,15-Tetraamine (abbreviation: DBC1), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 3,6-Diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 9,10-Bis(3,5-Diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-Di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-Di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-Bianthryle (abbreviation: BANT), 9,9'-(Stilbene-3,3'-Dyyl)Difhenanthrene (abbreviation: DPNS), 9,9'-(Stilbene-4,4'-Dyyl)Difhenanthrene (abbreviation: DPNS2), Examples include 3,3',3''-(benzene-1,3,5-triyl)tripyrene (abbreviated: TPB3). Additionally, among these materials and known materials, it is preferable to select and use one or more types of materials having an energy gap larger than the energy gap of the guest material (121).

[0285] Additionally, the light-emitting layer (120) may be composed of multiple layers, such as two or more layers. For example, when the first light-emitting layer and the second light-emitting layer are sequentially stacked from the hole transport layer side to form the light-emitting layer (120), a material having hole transport properties is used as the host material of the first light-emitting layer, and a material having electron transport properties is used as the host material of the second light-emitting layer.

[0286] Additionally, the host material (122) in the light-emitting layer (120) may be composed of one type of compound or may be composed of multiple compounds. Alternatively, the light-emitting layer (120) may have materials other than the host material (122) and the guest material (121).

[0287] <<Materials that can be used for the light-emitting layer (140)>>

[0288] Among the light-emitting layer (140), the host material (142) is present in the largest weight ratio, and the guest material (141) (phosphorescent material) is dispersed within the host material (142). It is preferable that the T1 level of the host material (142) (organic compound (142_1) and organic compound (142_2)) of the light-emitting layer (140) is higher than the T1 level of the guest material (141).

[0289] Examples of organic compounds (142_1) include, in addition to zinc or aluminum-based metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, phenanthroline derivatives, etc. Other examples include aromatic amines or carbazole derivatives. Specifically, electron transport materials and hole transport materials as shown in Example 1 may be used.

[0290] As for the organic compound (142_2), a combination capable of forming an excited complex with the organic compound (142_1) is preferred. Specifically, the electron transport material and hole transport material described in Embodiment 1 may be used. In this case, it is preferable to select the organic compound (142_1), the organic compound (142_2), and the guest material (141) (phosphorescent material) such that the emission peak of the excited complex formed by the organic compound (142_1) and the organic compound (142_2) overlaps with the absorption band of the triplet MLCT (Metal to Ligand Charge Transfer) transition of the guest material (141) (phosphorescent material), more specifically, with the absorption band on the longest wavelength side. By doing so, a light-emitting device with dramatically improved luminous efficiency can be produced. However, if a thermally activated delayed fluorescent material is used instead of the phosphorescent material, it is preferable that the absorption band on the longest wavelength side is a singlet absorption band.

[0291] As a guest material (141) (phosphorescent material), iridium, rhodium, or platinum-based organometallic complexes or metal complexes may be used, and among these, an organoiridium complex, for example, an iridium-based orthometallic complex, is preferred. Examples of orthometallic ligands may include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, or isoquinoline ligands. Examples of metal complexes may include platinum complexes having porphyrin ligands. Specifically, the material exemplified as the guest material (132) shown in Embodiment 1 may be used.

[0292] As for the light-emitting material included in the light-emitting layer (140), it is preferable to use a material capable of converting triplet excited energy into light emission. In addition to phosphorescent materials, thermally activated delayed fluorescent materials may be used as materials capable of converting triplet excited energy into light emission. Therefore, regarding the part described as phosphorescent material, it may be read as thermally activated delayed fluorescent material.

[0293] In addition, the material exhibiting thermally activated delayed fluorescence may be a material capable of generating a singlet excited state from a triplet excited state by crossover between inverse terms alone, or it may be composed of multiple materials forming an excited complex (also called an exciplex).

[0294] When the thermally activated delayed fluorescent material is composed of one type of material, specifically, the thermally activated delayed fluorescent material shown in Embodiment 1 can be used.

[0295] In addition, when using a thermally activated delayed fluorescent material as a host material, it is preferable to use a combination of two types of compounds that form an excited complex. In this case, it is particularly preferable to use a combination of an electron-accepting compound and a hole-accepting compound that forms the aforementioned excited complex.

[0296] <<Materials that can be used for the light-emitting layer (170)>>

[0297] As for the material that can be used for the light-emitting layer (170), it is preferable to use the material that can be used for the light-emitting layer shown in Embodiment 1, and by doing so, a light-emitting device with high light-emitting efficiency can be produced.

[0298] In addition, there are no limitations on the light emission colors of the light-emitting materials included in the light-emitting layer (120), the light-emitting layer (140), and the light-emitting layer (170); they may be the same or different. Since the light emission obtained from each is mixed and extracted out of the device, for example, if the light emission colors of both are in a complementary relationship, the light-emitting device can provide white light. Considering the reliability of the light-emitting device, it is preferable that the light emission peak wavelength of the light-emitting material included in the light-emitting layer (120) is shorter than that of the light-emitting material included in the light-emitting layer (170).

[0299] Additionally, the light-emitting unit (106), light-emitting unit (108), light-emitting unit (110), and charge-generating layer (115) can be formed by a deposition method (including vacuum deposition), an inkjet method, a coating method, gravure printing, etc.

[0300] The configuration shown in the above embodiment can be used in appropriate combination with the configuration shown in other embodiments.

[0301] (Embodiment 3)

[0302] FIG. 5 (A) is a top view illustrating a light-emitting device, and FIG. 5 (B) is a cross-sectional view of FIG. 5 (A) taken along AB and CD. This light-emitting device controls the light emission of a light-emitting element and includes a driving circuit section (source side driving circuit) (601), a pixel section (602), and a driving circuit section (gate side driving circuit) (603) indicated by a dotted line. Additionally, 604 is a sealing substrate, 625 is a drying material, and 605 is a sealing material, and the inner side surrounded by the sealing material (605) is a space (607).

[0303] Additionally, the lead wiring (608) is wiring for transmitting signals input to the source-side driving circuit (601) and the gate-side driving circuit (603), and receives video signals, clock signals, start signals, reset signals, etc. from the Flexible Printed Circuit (FPC) (609) which serves as an external input terminal. Although only the FPC is shown here, a Printed Wiring Board (PWB) may be mounted on the FPC. The light-emitting device in this specification includes not only the main body of the light-emitting device but also a state in which an FPC or PWB is mounted thereon.

[0304] Next, the cross-sectional structure of the light-emitting device described above will be explained using (B) of FIG. 5. Although a driving circuit and a pixel are formed on the element substrate (610), the source side driving circuit (601), which is the driving circuit, and one pixel within the pixel section (602) are shown here.

[0305] In addition, a CMOS circuit is formed in the source-side driving circuit (601) by combining an n-channel type TFT (623) and a p-channel type TFT (624). In addition, the driving circuit may be formed with various CMOS circuits, PMOS circuits, and NMOS circuits. In addition, in this embodiment, a driver integrated type is shown in which the driving circuit is formed on the substrate, but it is not necessary to do so, and the driving circuit may be formed externally rather than on the substrate.

[0306] Additionally, the pixel portion (602) is formed by a pixel comprising a switching TFT (611), a current control TFT (612), and a first electrode (613) electrically connected to the drain thereof. Additionally, an insulating material (614) is formed by covering the end of the first electrode (613). The insulating material (614) can be formed by using a positive-type photosensitive resin film.

[0307] In addition, to ensure good coverage of the film formed on the insulating material (614), a surface having a curvature is formed on the upper or lower part of the insulating material (614). For example, when photosensitive acrylic is used as the material of the insulating material (614), it is preferable to have a curved surface only on the upper part of the insulating material (614). It is preferable that the radius of curvature of the curved surface be 0.2 μm or more and 0.3 μm or less. In addition, both negative-type photosensitive materials and positive-type photosensitive materials can be used as the insulating material (614).

[0308] An EL layer (616) and a second electrode (617) are formed respectively on the first electrode (613). Here, it is preferable to use a material with a high work function as the material used for the first electrode (613) which functions as an anode. For example, in addition to single-layer films such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, and a Pt film, a laminate of a titanium nitride film and a film mainly composed of aluminum, or a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Furthermore, if a laminated structure is used, the resistance as wiring is low, a good ohmic contact is obtained, and it can also function as an anode.

[0309] In addition, the EL layer (616) is formed by various methods such as deposition using a deposition mask, inkjet method, and spin coating method. The material constituting the EL layer (616) may be a low-molecular-weight compound or a high-molecular-weight compound (including oligomers and dendrimers).

[0310] In addition, as a material used for the second electrode (617) which is formed on the EL layer (616) and functions as a cathode, it is preferable to use a material with a low work function (Al, Mg, Li, Ca, or alloys or compounds thereof, MgAg, MgIn, AlLi, etc.). Also, when light generated from the EL layer (616) passes through the second electrode (617), it is preferable to use a stack of a metal thin film with a thin film thickness and a transparent conductive film (ITO, indium oxide containing 2 wt% or more and 20 wt% or less of zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) as the second electrode (617).

[0311] Additionally, a light-emitting element (618) is formed by the first electrode (613), the EL layer (616), and the second electrode (617). It is preferable that the light-emitting element (618) is a light-emitting element having the configuration of Embodiment 1 and Embodiment 2. Additionally, although the pixel portion is formed by a plurality of light-emitting elements, the light-emitting device in this embodiment may include both the light-emitting element having the configuration described in Embodiment 1 and Embodiment 2 and the light-emitting element having other configurations.

[0312] In addition, the structure is such that a light-emitting element (618) is provided in a space (607) surrounded by the element substrate (610), the sealing substrate (604), and the actual material (605) by joining the sealing substrate (604) to the element substrate (610). In addition, the space (607) is filled with a filler material, and in addition to being filled with an inert gas (such as nitrogen or argon), it may also be filled with a resin or a drying material, or both.

[0313] In addition, it is preferable to use epoxy resin or glass frit in the actual (605). It is also preferable that these materials be materials that do not allow moisture or oxygen to pass through as much as possible. In addition, as a material used for the sealing substrate (604), in addition to glass substrates or quartz substrates, plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, or acrylic can be used.

[0314] As described above, a light-emitting device using the light-emitting element described in Embodiment 1 and Embodiment 2 can be obtained.

[0315] <Configuration Example 1 of a Light-emitting Device>

[0316] Figure 6 illustrates an example of a light-emitting device in which a light-emitting element exhibiting white light emission is formed and a coloring layer (color filter) is formed.

[0317] Figure 6 (A) illustrates a substrate (1001), a lower insulating film (1002), a gate insulating film (1003), a gate electrode (1006), a gate electrode (1007), a gate electrode (1008), a first interlayer insulating film (1020), a second interlayer insulating film (1021), a peripheral part (1042), a pixel part (1040), a driving circuit part (1041), a first electrode (1024W), a first electrode (1024R), a first electrode (1024G), a first electrode (1024B) of a light-emitting element, a partition (1026), an EL layer (1028), a second electrode (1029) of a light-emitting element, a sealing substrate (1031), an actual part (1032), etc.

[0318] In addition, in FIG. 6 (A) and (B), a colored layer (a red colored layer (1034R), a green colored layer (1034G), and a blue colored layer (1034B)) is provided on a transparent substrate (1033). Additionally, a black layer (black matrix) (1035) may be provided. The transparent substrate (1033) provided with the colored layer and the black layer is positioned and fixed to the substrate (1001). Additionally, the colored layer and the black layer are covered with an overcoat layer (1036). Also, in FIG. 6 (A), there is a light-emitting layer in which light does not pass through the colored layer and exits to the outside, and a light-emitting layer in which light passes through each colored layer of a different color and exits to the outside. Since the light that does not pass through the colored layer becomes white, and the light that passes through the colored layer becomes red, blue, and green, an image can be expressed with four-color pixels.

[0319] In FIG. 6 (B), an example is illustrated in which a red colored layer (1034R), a green colored layer (1034G), and a blue colored layer (1034B) are formed between the gate insulating film (1003) and the first interlayer insulating film (1020). As shown in FIG. 6 (B), the colored layer may be provided between the substrate (1001) and the sealing substrate (1031).

[0320] In addition, the light-emitting device described above is a light-emitting device with a structure (bottom emission type) that extracts light toward the substrate (1001) on which the TFT is formed, but it may also be a light-emitting device with a structure (top emission type) that extracts light toward the sealed substrate (1031).

[0321] <Configuration Example 2 of a Light-emitting Device>

[0322] A cross-sectional view of a top-emission type light-emitting device is shown in FIG. 7. In this case, a substrate that does not transmit light may be used for the substrate (1001). It is formed in the same way as a bottom-emission type light-emitting device until a connecting electrode connecting the TFT and the positive electrode of the light-emitting element is fabricated. After that, a third interlayer insulating film (1037) is formed by covering the electrode (1022). This insulating film may serve a flattening function. The third interlayer insulating film (1037) can be formed using various other materials in addition to the same material as the second interlayer insulating film (1021).

[0323] The first lower electrode (1025W), lower electrode (1025R), lower electrode (1025G), and lower electrode (1025B) of the light-emitting element are positive electrodes here, but they may also be negative electrodes. In addition, in the case of a top-emission type light-emitting device as shown in FIG. 7, it is preferable to make the lower electrode (1025W), lower electrode (1025R), lower electrode (1025G), and lower electrode (1025B) reflective electrodes. In addition, it is preferable for the second electrode (1029) to have a function of reflecting light and a function of transmitting light. In addition, it is preferable to have a function of amplifying light of a specific wavelength by applying a microcavity structure between the second electrode (1029) and the lower electrode (1025W), lower electrode (1025R), lower electrode (1025G), and lower electrode (1025B). The configuration of the EL layer (1028) is configured as described in Embodiment 2, and is a device structure capable of obtaining white light emission.

[0324] In FIGS. 6 (A), (B) and FIG. 7, the configuration of the EL layer capable of obtaining white light emission can be realized by using multiple light-emitting layers, using multiple light-emitting units, etc. Furthermore, the configuration for obtaining white light emission is not limited to this.

[0325] In a top emission structure as shown in FIG. 7, it can be sealed with a sealing substrate (1031) that provides a colored layer (red colored layer (1034R), green colored layer (1034G), blue colored layer (1034B)). The sealing substrate (1031) may also be provided with a black layer (black matrix) (1035) positioned between pixels. The colored layers (red colored layer (1034R), green colored layer (1034G), blue colored layer (1034B)) or the black layer (black matrix) may be covered with an overcoat layer. Additionally, the sealing substrate (1031) may use a transparent substrate.

[0326] In addition, although an example of performing a full-color display using four colors—red, green, blue, and white—has been shown here, it is not specifically limited to three colors—red, green, and blue—and a full-color display may also be performed using three colors. In addition, a full-color display may also be performed using four colors—red, green, blue, and yellow.

[0327] As described above, a light-emitting device using the light-emitting element described in Embodiment 1 and Embodiment 2 can be obtained.

[0328] In addition, this embodiment can be appropriately combined with other embodiments.

[0329] (Embodiment 4)

[0330] In this embodiment, an electronic device of one form of the present invention is described.

[0331] Since one embodiment of the present invention is a light-emitting device using organic EL, a highly reliable electronic device with good light-emitting efficiency can be manufactured having a planar surface. In addition, according to one embodiment of the present invention, a highly reliable electronic device with good light-emitting efficiency can be manufactured having a curved surface. In addition, according to one embodiment of the present invention, a highly reliable electronic device with good light-emitting efficiency can be manufactured having flexibility.

[0332] Examples of electronic devices include televisions, desktop or laptop personal computers, monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, portable information terminals, sound playback devices, and large game machines such as pachinko machines.

[0333] In addition, a light-emitting device of one form of the present invention can achieve high visibility regardless of the intensity of external light. Therefore, it can be suitably used in portable electronic devices, wearable electronic devices, and electronic book terminals.

[0334] The portable information terminal (900) illustrated in (A) and (B) of FIG. 8 has a housing (901), a housing (902), a display unit (903), and a hinge unit (905), etc.

[0335] Housing (901) and housing (902) are connected by a hinge portion (905). The portable information terminal (900) can be unfolded from a folded state ((A) of FIG. 8) as shown in (B) of FIG. 8. Accordingly, portability is excellent when carrying it, and visibility is excellent due to the large display area when using it.

[0336] A portable information terminal (900) is provided with a flexible display (903) extending across a housing (901) and a housing (902) connected by a hinge portion (905).

[0337] A light-emitting device manufactured using one embodiment of the present invention can be used in the display unit (903). By doing so, a portable information terminal can be manufactured with a high yield.

[0338] The display unit (903) can display at least one of document information, a still image, and a video. When document information is displayed on the display unit, the portable information terminal (900) can be used as an electronic book terminal.

[0339] When the portable information terminal (900) is unfolded, the display portion (903) is maintained in a greatly curved shape. For example, the display portion (903) is maintained including a curved portion with a radius of curvature of 1 mm or more and 50 mm or less, preferably 5 mm or more and 30 mm or less. A portion of the display portion (903) has pixels arranged continuously from the housing (901) to the housing (902) so that a curved shape display can be performed.

[0340] The display unit (903) functions as a touch panel and can be operated with a finger or a stylus.

[0341] It is preferable that the display unit (903) be composed of a single flexible display. This allows for continuous display without interruption between the housing (901) and the housing (902). Additionally, the configuration may be such that a display is provided on each of the housing (901) and the housing (902).

[0342] It is preferable that the hinge portion (905) has a locking mechanism so that when the portable information terminal (900) is unfolded, the angle between the housing (901) and the housing (902) does not become greater than a predetermined angle. For example, the angle at which the lock is engaged (preventing it from unfolding further) is preferably 90 degrees or more and less than 180 degrees, and can be typically 90 degrees, 120 degrees, 135 degrees, 150 degrees, or 175 degrees. By doing so, the convenience, safety, and reliability of the portable information terminal (900) can be enhanced.

[0343] If the hinge part (905) has a locking mechanism, no excessive force is applied to the display part (903), so the display part (903) can be prevented from being damaged. Therefore, a highly reliable portable information terminal can be realized.

[0344] Housing (901) and housing (902) may have a power button, an operation button, an external connection port, a speaker, a microphone, etc.

[0345] A wireless communication module is provided in either the housing (901) or the housing (902) to transmit and receive data through a computer network such as the Internet, LAN (Local Area Network), or Wi-Fi (registered trademark).

[0346] The portable information terminal (910) illustrated in (C) of FIG. 8 has a housing (911), a display unit (912), an operation button (913), an external connection port (914), a speaker (915), a microphone (916), a camera (917), etc.

[0347] A light-emitting device manufactured using one embodiment of the present invention can be used in the display unit (912). By doing so, a portable information terminal can be manufactured with a high yield.

[0348] A portable information terminal (910) is provided with a touch sensor on the display unit (912). Various operations, such as making a phone call or entering text, can be performed by touching the display unit (912) with a finger, a stylus, etc.

[0349] In addition, the power can be turned ON or OFF or the type of image displayed on the display unit (912) can be switched by operating the control button (913). For example, the email composition screen can be switched to the main menu screen.

[0350] In addition, by providing a detection device such as a gyroscope or an accelerometer inside the portable information terminal (910), the orientation of the portable information terminal (910) (whether vertical or horizontal) can be determined, and the orientation of the screen display of the display unit (912) can be automatically switched. In addition, the switching of the screen display orientation may be performed by touching the display unit (912), operating an operation button (913), or voice input using a microphone (916).

[0351] The portable information terminal (910) has one or more functions selected from, for example, a telephone, a notebook, and an information viewing device. Specifically, it can be used as a smartphone. The portable information terminal (910) can execute various applications such as, for example, mobile phone, email, viewing and writing text, music playback, video playback, internet communication, and games.

[0352] The camera (920) illustrated in (D) of FIG. 8 has a housing (921), a display (922), an operation button (923), a shutter button (924), etc. Additionally, the camera (920) is equipped with a detachable lens (926).

[0353] A light-emitting device manufactured using one embodiment of the present invention can be used in the display unit (922). By doing so, a camera can be manufactured with a high yield.

[0354] Here, the camera (920) is configured so that the lens (926) can be detached from the housing (921) and replaced, but the lens (926) and the housing (921) may be integrated.

[0355] The camera (920) can capture a still image or video by pressing the shutter button (924). Additionally, the display unit (922) functions as a touch panel, and can also capture an image by touching the display unit (922).

[0356] Additionally, the camera (920) may be equipped with a strobe device or a viewfinder separately. Alternatively, these may be included in the housing (921).

[0357] Figures 9 (A) to (E) are drawings showing electronic devices. These electronic devices have a housing (9000), a display unit (9001), a speaker (9003), an operation key (9005) (including a power switch or an operation switch), a connection terminal (9006), a sensor (9007) (including a function to measure force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, longitude, electric field, current, voltage, power, radiation, flow rate, humidity, inclination, vibration, smell, or infrared radiation), a microphone (9008), etc.

[0358] A light-emitting device manufactured using one embodiment of the present invention can be suitably used in a display unit (9001). By doing so, an electronic device can be manufactured with a high yield.

[0359] The electronic device illustrated in FIGS. 9 (A) to (E) may have various functions. For example, it may have a function of displaying various information (still images, video, text images, etc.) on a display unit, a touch panel function, a function of displaying a calendar, date, or time, a function of controlling processing by various software (programs), a wireless communication function, a function of connecting to various computer networks using a wireless communication function, a function of performing transmission or reception of various data using a wireless communication function, and a function of reading a program or data recorded on a recording medium and displaying it on a display unit. Furthermore, the functions of the electronic device illustrated in FIGS. 9 (A) to (E) are not limited to these, and it may have other functions.

[0360] FIG. 9 (A) is a perspective view illustrating a wristwatch-type portable information terminal (9200), and FIG. 9 (B) is a perspective view illustrating a wristwatch-type portable information terminal (9201).

[0361] The portable information terminal (9200) illustrated in FIG. 9 (A) can execute various applications such as mobile phone, email, text viewing and composition, music playback, internet communication, and computer games. Additionally, the display unit (9001) is provided with a curved display surface and can perform display along the curved display surface. Furthermore, the portable information terminal (9200) can perform short-range wireless communication according to communication standards. For example, hands-free calling can be performed by communicating with a wirelessly capable headset. Additionally, the portable information terminal (9200) has a connection terminal (9006) and can directly exchange data with another information terminal through a connector. Charging can also be performed through the connection terminal (9006). Additionally, the charging operation may be performed by wireless power supply without using the connection terminal (9006).

[0362] Unlike the portable information terminal (9201) shown in Fig. 9 (A) shown in Fig. 9, the display surface of the display unit (9001) of the portable information terminal (9201) is not curved. In addition, the shape of the display unit of the portable information terminal (9201) is non-rectangular (circular in Fig. 9 (B)).

[0363] FIGS. 9 (C) to (E) are perspective views illustrating a foldable portable information terminal (9202). FIGS. 9 (C) is a perspective view of the portable information terminal (9202) in an unfolded state, FIGS. 9 (D) is a perspective view of the portable information terminal (9202) in a state of transition from one side of the unfolded or folded state to the other, and FIGS. 9 (E) is a perspective view of the portable information terminal (9202) in a folded state.

[0364] The portable information terminal (9202) has excellent portability when folded and excellent visibility of the display due to a wide, seamless display area when unfolded. The display portion (9001) of the portable information terminal (9202) is supported by three housings (9000) connected by a hinge (9055). By bending the space between two housings (9000) using the hinge (9055), the portable information terminal (9202) can be reversibly deformed from an unfolded state to a folded state. For example, the portable information terminal (9202) can be bent with a radius of curvature of 1 mm or more and 150 mm or less.

[0365] This embodiment can be appropriately combined with other embodiments.

[0366] (Embodiment 5)

[0367] In this embodiment, an example of applying a light-emitting element of one form of the present invention to various lighting devices is described using FIGS. 10 and 11. By using a light-emitting element of one form of the present invention, a highly reliable lighting device with good light-emitting efficiency can be manufactured.

[0368] By fabricating a light-emitting element of one form of the present invention on a flexible substrate, an electronic device or lighting device having a light-emitting region having a curved surface can be realized.

[0369] In addition, a light-emitting device incorporating a light-emitting element of one form of the present invention can also be applied to lighting of an automobile, and lighting can be installed, for example, on the windshield, ceiling, etc.

[0370] FIG. 10 (A) shows a perspective view of one side of a multifunctional terminal (3500), and FIG. 10 (B) shows a perspective view of the other side of a multifunctional terminal (3500). The multifunctional terminal (3500) includes a display unit (3504), a camera (3506), a light (3508), etc. in a housing (3502). A light-emitting device of one form of the present invention can be used for the light (3508).

[0371] The lighting (3508) functions as a surface light source by using a light-emitting device of one form of the present invention. Therefore, unlike point light sources such as LEDs (Light Emitting Diodes), light with low directionality can be obtained. For example, when the lighting (3508) and the camera (3506) are used in combination, the lighting (3508) can be turned on or turned on to capture images by the camera (3506). Since the lighting (3508) functions as a surface light source, it is possible to take a photograph that looks like it was taken under natural light.

[0372] In addition, the multifunctional terminal (3500) shown in (A) and (B) of FIG. 10 can have various functions, just like the electronic device shown in (A) to (C) of FIG. 9.

[0373] Additionally, the housing (3502) may have a speaker, a sensor (including a function to measure force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, longitude, electric field, current, voltage, power, radiation, flow rate, humidity, inclination, vibration, smell, or infrared), a microphone, etc., inside. Furthermore, by providing a detection device having a sensor that detects tilt, such as a gyroscope sensor or an accelerometer sensor, inside the multi-functional terminal (3500), the orientation of the multi-functional terminal (3500) (whether vertical or horizontal) can be determined, and the screen display of the display unit (3504) can be automatically switched.

[0374] The display unit (3504) may function as an image sensor. For example, personal authentication can be performed by touching the display unit (3504) with a palm or finger to capture a palm print, fingerprint, etc. Additionally, if a backlight emitting near-infrared light or a sensing light source emitting near-infrared light is used on the display unit (3504), finger veins, palm veins, etc. may be captured. Furthermore, a light-emitting device of one form of the present invention may be applied to the display unit (3504).

[0375] Figure 10 (C) shows a perspective view of a security light (3600). The light (3600) has a light source (3608) on the outside of a housing (3602), and the housing (3602) includes a speaker (3610), etc. A light-emitting element of one form of the present invention can be used for the light source (3608).

[0376] The light (3600) may emit light by, for example, holding, grasping, or maintaining the light source (3608). Additionally, an electronic circuit capable of controlling the method of light emission from the light (3600) may be provided inside the housing (3602). The electronic circuit may be, for example, a circuit capable of enabling light emission once or intermittently multiple times, or a circuit capable of adjusting the amount of light emission by controlling the current value of the light emission. Additionally, a circuit may be included that outputs a loud alarm sound from the speaker (3610) simultaneously with the light emission of the light source (3608).

[0377] Since the light (3600) can emit light in various directions, it can be turned toward, for example, a violent person to threaten them with light or light and sound. Additionally, by providing a camera such as a digital still camera to the light (3600), a function to take photos may be provided.

[0378] FIG. 11 is an example in which a light-emitting element is used as an indoor lighting device (8501). Additionally, since the light-emitting element can be made large in area, a large-area lighting device can be formed. Furthermore, by using a housing having a curved surface, a lighting device (8502) having a curved light-emitting area can be formed. The light-emitting element shown in this embodiment is in the form of a thin film, and the design freedom of the housing is high. Therefore, lighting devices designed in various ways can be formed. Additionally, a large lighting device (8503) may be provided on an indoor wall. Additionally, touch sensors may be provided on the lighting device (8501), lighting device (8502), and lighting device (8503) to perform power on or off.

[0379] In addition, by using a light-emitting element on the surface side of the table, it can be made into a lighting device (8504) that functions as a table. In addition, by using a light-emitting element on a part of other furniture, it can be made into a lighting device that functions as furniture.

[0380] By doing as described above, a lighting device and an electronic device can be obtained by applying a light-emitting device of one form of the present invention. Furthermore, the lighting device and electronic device to which it can be applied are not limited to those shown in the present embodiment, but can be applied to electronic devices in various fields.

[0381] In addition, the configuration shown in this embodiment can be used in appropriate combination with the configuration shown in other embodiments.

[0382] (Example 1)

[0383] In this embodiment, an example of fabrication of a light-emitting element, which is a type of electronic device according to one embodiment of the present invention, and the characteristics of the light-emitting element are described. In addition, the refractive index of the organic compound used in the hole injection layer and the refractive index of the hole injection layer are described. A cross-sectional view of the device structure fabricated in this embodiment is shown in FIG. 2 (A). In addition, details of the device structure are shown in Table 1. Furthermore, the structure and abbreviation of the compound used are shown below.

[0384] [Chemical Formula 7]

[0385]

[0387] [Table 1]

[0388]

[0389] [Table 2]

[0390]

[0391] [Table 3]

[0392]

[0393] Measurement of Refractive Index

[0394] The organic compounds used in the hole injection layer (111) of comparative light-emitting elements 1 to 4, light-emitting elements 5 to 8, and light-emitting elements 9 to 12, and the refractive index of the hole injection layer (111) were measured. The refractive index was measured at room temperature using a rotating compensator type multi-angle incident high-speed spectroscopic ellipsometer (M-2000U) manufactured by JAWoolam. The measurement samples were prepared by vacuum deposition on a quartz substrate. The n Ordinary and n Extraordinary values ​​were measured to calculate the n average.

[0395] The results of measuring the refractive index of each film in light with a wavelength of 532 nm are shown in Fig. 12. From Fig. 12, it was found that DBT3P-II, used in comparative light-emitting elements 1 to 4, has the highest refractive index. It was found that dmCBP, used in light-emitting elements 5 to 8, is an organic compound with a low refractive index, with an n Ordinary of 1.75 or less. In addition, it was found that TAPC, used in light-emitting elements 9 to 12, is an organic compound with a very low refractive index, with an n Ordinary of 1.70 or less.

[0396] In addition, since hole injection properties are required for the hole injection layer (111), it is desirable to have an electron-donating material. The hole injection layer (111) of each light-emitting device using MoO3, which has a high refractive index, as the electron-donating material is expected to have a high refractive index. However, from FIG. 12, it was found that the refractive index of the film in which MoO3, which is the hole injection layer (111) of each light-emitting device, is added to each organic compound is only slightly higher than the refractive index of each organic compound. That is, by using an organic compound with a low refractive index for the hole injection layer (111), it was found that a hole injection layer (111) with a low refractive index can be obtained even if a material with a high refractive index is used for the electron-donating material.

[0397] In addition, from FIG. 12, it was found that the hole injection layer (111) of each light-emitting element has a smaller difference between n Ordinary and n Extraordinary than the film of each organic compound. That is, it was found that the mixed film of MoO3, which is an electron-accepting material, and an organic compound has reduced anisotropy compared to the organic compound film.

[0398] Fabrication of light-emitting devices

[0399] <<Fabrication of Comparative Light Emitting Devices 1 to 4>> An ITSO film was formed on a glass substrate as an electrode (101) with a thickness of 70 nm. In addition, the electrode area of ​​the electrode (101) is 4 mm 2 It was made (2mm×2mm). Also, the refractive index (n Ordinary) of the ITSO film at a wavelength of 532nm is 2.07.

[0400] Next, as a hole injection layer (111) on the electrode (101), 1,3,5-tri-(4-dibenzothiophenyl)-benzene (abbreviated: DBT3P-II) and MoO3 were co-deposited with a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of x1 nm. Additionally, the value of x1 is different for each light-emitting element, and the value of x1 for each light-emitting element is the value shown in Table 2.

[0401] Next, PCCP was deposited on the hole injection layer (111) as a hole transport layer (112) with a thickness of 20 nm.

[0402] Next, as a light-emitting layer (130(1)) on the hole transport layer (112), 4,6mCzP2Pm, PCCP, and Ir(pbi-diBuCNp)3 (a mixture of fac isomer:mer isomer = 3:2) were co-deposited with a weight ratio (4,6mCzP2Pm:PCCP:Ir(pbi-diBuCNp)3) of 0.5:0.5:0.1 and a thickness of 20nm, and then as a light-emitting layer (130(2)), a weight ratio (4,6mCzP2Pm:PCCP:Ir(pbi-diBuCNp)3) of 0.8:0.2:0.1 and a thickness of 20nm were co-deposited. Also, in the light-emitting layer (130(1)) and the light-emitting layer (130(2)), Ir(pbi-diBuCNp)3 is a guest material that exhibits phosphorescent light emission.

[0403] Next, 4,6 mCz P2Pm was co-deposited on the light-emitting layer (130(2)) as a first electron transport layer (118(1)) with a thickness of 20 nm. Subsequently, vasophenanthroline (abbreviated as BPhen) was deposited on the first electron transport layer (118(1)) as a second electron transport layer (118(2)) with a film thickness of 10 nm.

[0404] Next, lithium fluoride (LiF) was deposited on the second electron transport layer (118(2)) as an electron injection layer (119) with a thickness of 1 nm.

[0405] Next, aluminum (Al) was formed as an electrode (102) on the electron injection layer (119) with a thickness of 200 nm.

[0406] Next, comparative light-emitting elements 1 to 4 were sealed inside a glove box in a nitrogen atmosphere by fixing a glass substrate for sealing using a sealant for organic EL to a glass substrate on which an organic material was formed. Specifically, a sealant was applied around the organic material on the glass substrate on which the organic material was formed, and this substrate was bonded to the glass substrate for sealing, thereby emitting ultraviolet light with a wavelength of 365 nm at 6 J / cm² 2 The sample was investigated and heat-treated at 80°C for 1 hour. Comparative light-emitting elements 1 to 4 were obtained by the above-described process.

[0407] <<Fabrication of Light-emitting Elements 5 to 8>>

[0408] The fabrication process of light-emitting elements 5 to 8 is different only in the fabrication process of the hole injection layer (111) as in the fabrication process of comparative light-emitting elements 1 to 4, and the other processes are performed in the same way as comparative light-emitting elements 1 to 4.

[0409] As a hole injection layer (111(1)) on the electrode (101), dmCBP and MoO3 were co-deposited with a weight ratio (dmCBP:MoO3) of 2:0.5 and a thickness of 35 nm, and then DBT3P-II and MoO3 were co-deposited with a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of x2 nm. In addition, the value of x2 is different for each light-emitting element, and the value of x2 for each light-emitting element is the value shown in Table 3.

[0410] <<Fabrication of Light-emitting Elements 9 to 12>>

[0411] The fabrication process of light-emitting elements 9 to 12 is different only in the fabrication process of the hole injection layer (111) as in the fabrication process of comparative light-emitting elements 1 to 4, and the other processes are performed in the same way as comparative light-emitting elements 1 to 4.

[0412] As a hole injection layer (111(1)) on the electrode (101), TAPC and MoO3 were co-deposited with a weight ratio (TAPC:MoO3) of 2:0.5 and a thickness of 35 nm, and then DBT3P-II and MoO3 were co-deposited with a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of x2 nm. In addition, the value of x2 is different for each light-emitting element, and the value of x2 for each light-emitting element is the value shown in Table 3.

[0413] Characteristics of light-emitting devices

[0414] Next, the characteristics of the fabricated comparative light-emitting elements 1 to 4 and light-emitting elements 5 to 12 were measured. A colorimeter (BM-5A, manufactured by Topcon Technohouse Corporation) was used to measure luminance and CIE chromaticity, and a multichannel spectrometer (PMA-11, manufactured by Hamamatsu Photonics KK) was used to measure the electroluminescence spectrum. In addition, measurements of each light-emitting element were performed at room temperature (an atmosphere maintained at 23°C).

[0415] Among the fabricated light-emitting elements, the current efficiency-luminance characteristics of comparison light-emitting element 1, light-emitting element 5, and light-emitting element 9 are shown in FIG. 13. The current density-voltage characteristics are also shown in FIG. 14. Additionally, the external quantum efficiency-luminance characteristics are shown in FIG. 15. Furthermore, the value of the external quantum efficiency shown in FIG. 15 is the external quantum efficiency when measured from the front direction with respect to the light-emitting element without performing viewing angle correction. Additionally, regarding the organic compound of the hole injection layer (111), comparison light-emitting element 1 uses DBT3P-II, light-emitting element 5 uses dmCBP, and light-emitting element 9 uses TAPC, and all parts other than the hole injection layer (111) have the same device structure.

[0416] From FIG. 14, it was found that comparative light-emitting elements 1, emitting element 5, and emitting element 9 have equivalent current density-voltage characteristics. Therefore, it was found that even if an organic compound with a low refractive index is used in the hole injection layer (111), good hole injection characteristics are obtained.

[0417] In addition, from FIGS. 13 and 15, it was found that comparative light-emitting element 1, light-emitting element 5, and light-emitting element 9 have a high current efficiency exceeding 100 cd / A and a high external quantum efficiency exceeding 30%. Furthermore, light-emitting element 5 and light-emitting element 9, which use dmCBP and TAPC, which are organic compounds with low refractive index, in the hole injection layer (111), showed higher efficiency than comparative light-emitting element 1, which uses DBT3P-II, which is a material with a high refractive index.

[0418] In addition, 25 mA / cm² for comparative light-emitting elements 1, light-emitting element 5, and light-emitting element 9 2 The emission spectrum when current is passed at a current density is shown in FIG. 16. As shown in FIG. 16, the emission spectra of comparative emission element 1, emission element 5, and emission element 9 have peaks around 515 nm and 550 nm, and it was found that they originate from the emission of Ir(pbi-diBuCNp)3, a guest material included in the emission layer (130).

[0419] In addition, 1000 cd / m of comparative light-emitting elements 1 to 4, and light-emitting elements 5 to 12 2 The device characteristics in the vicinity are shown in Table 4. The external quantum efficiency shown in Table 4 represents the external quantum efficiency after performing viewing angle correction.

[0420] [Table 4]

[0421]

[0422] From the above results, it can be seen that the comparative light-emitting elements 1 to 4 and light-emitting elements 5 to 12 produced in this embodiment exhibit good driving voltage and light-emitting efficiency regardless of the structure of the hole injection layer (111).

[0423] <Relationship between the refractive index of the hole injection layer (111) and the external quantum efficiency>

[0424] In FIG. 17, the relationship between chromaticity x and external quantum efficiency according to the organic material used in each hole injection layer (111) is shown using the values ​​of each element shown in Table 4. In FIG. 17, the values ​​of comparative light-emitting elements 1 to 4 are used for the curve data of "DBT3P-II", the values ​​of light-emitting elements 5 to 8 are used for the curve data of "dmCBP", and the values ​​of light-emitting elements 9 to 12 are used for the curve data of "TAPC". Here, in comparative light-emitting elements 1 to 4 and light-emitting elements 5 to 12, even if the film thickness of the hole injection layer (111) is the same, the refractive index differs depending on the organic compound used, so the optical path length from the light-emitting region of each light-emitting element to the substrate changes. When the optical path length changes, the external quantum efficiency also changes, so when evaluating the relationship between the refractive index of the hole injection layer (111) and the external quantum efficiency, it is necessary to adjust the optical path length in each light-emitting element, but it is difficult to finely adjust the film thickness of the EL layer by fabricating the light-emitting element.

[0425] In light-emitting devices using the same light-emitting material, if the optical path length from the light-emitting region of each light-emitting device to the substrate is different, there will be differences in the light emission spectrum and chromaticity obtained from the light-emitting device. On the other hand, if the same chromaticity is obtained from each light-emitting device, the light emission spectrum extracted from each light-emitting device is considered to be the same. That is, if the same chromaticity is obtained from each light-emitting device, the optical path length from the light-emitting region of each light-emitting device to the substrate can be considered to be the same. Therefore, by considering the relationship between the external quantum efficiency and the chromaticity x or chromaticity y, the relationship between the refractive index of the hole injection layer (111) and the external quantum efficiency can be evaluated.

[0426] From FIG. 12, the organic compounds used in the hole injection layer (111) have higher refractive indices in the order of DBT3P-II > dmCBP > TAPC. From FIG. 17, it was found that the lower the refractive index of the organic compounds used in the hole injection layer (111), the higher the external quantum efficiency. This is because the attenuation of light due to the ebenescent mode is reduced and the light extraction efficiency is improved.

[0427] Above, it was found that by using an organic compound with a low refractive index in the hole injection layer (111), a light-emitting device with good light extraction efficiency is obtained while maintaining hole injection characteristics.

[0428] <Relationship between the volume ratio of electron-donating material and electron-accepting material in the hole injection layer (111) and the external quantum efficiency>

[0429] Here, the relationship between the volume ratio of the electron accepting material (MoO3) to the electron donating material in the hole injection layer (111) (hereinafter referred to as the volume ratio of MoO3) and the external quantum efficiency was investigated. In addition, details of the device structure are shown in Table 5. In addition, the structure and abbreviation of the compound used are shown below. In addition, for other organic compounds, it is recommended to refer to the compounds described above.

[0430] [Chemical Formula 8]

[0431]

[0432] [Table 5]

[0433]

[0434] [Table 6]

[0435]

[0436] <<Fabrication of light-emitting elements 13 to 18>>

[0437] The manufacturing process of light-emitting elements 13 to 18 is different from the manufacturing process of comparative light-emitting elements 1 to 4, only in the manufacturing process of the hole injection layer (111) and the light-emitting layer (130), and the other processes are performed in the same way as comparative light-emitting elements 1 to 4.

[0438] DBT3P-II and MoO3 were co-deposited on the electrode (101) as a hole injection layer (111) such that the weight ratio (DBT3P-II:MoO3) is 3-y:y and the thickness is 40 nm. Additionally, the value of y is different for each light-emitting element, and the value of y for each light-emitting element is shown in Table 6. In addition, the result of converting the weight ratio into the volume ratio of MoO3 is also shown in Table 6.

[0439] Next, as a light-emitting layer (130(1)) on the hole transport layer (112), 4,6 mCz P2Pm, PCCP, and Ir(tBuppm)3 are co-deposited with a weight ratio (4,6 mCz P2Pm:PCCP:Ir(tBuppm)3) of 0.5:0.5:0.075 and a thickness of 20 nm, and then as a light-emitting layer (130(2)), a weight ratio (4,6 mCz P2Pm:PCCP:Ir(tBuppm)3) of 0.8:0.2:0.075 and a thickness of 20 nm are co-deposited. In addition, in the light-emitting layer (130(1)) and the light-emitting layer (130(2)), Ir(tBuppm)3 is a guest material that exhibits phosphorescent light emission.

[0440] Characteristics of light-emitting devices

[0441] Next, the luminance-external quantum efficiency characteristics of the light-emitting elements (13) to (18) fabricated above were measured. The measurement was performed using the method described above.

[0442] In FIG. 18, 10,000 cd / m of each element 2The relationship between the external quantum efficiency in the vicinity and the volume ratio of MoO3 in the hole injection layer (111) is shown. From FIG. 18, it can be seen that in the region where the volume ratio of MoO3 is greater than 0 and less than 0.3 with respect to the electron-donating material, the external quantum efficiency showed a high efficiency of 24% to 26%, but in the region greater than 0.3, the efficiency decreased. This suggests that in the region where the volume ratio of MoO3 is greater than 0.3, the light extraction efficiency decreased because the refractive index of the hole injection layer (111) increased due to the influence of the electron-accepting material (MoO3) with a high refractive index. On the other hand, in the region where the volume ratio of MoO3 is greater than 0 and less than 0.3, the influence of the electron-accepting material (MoO3) with a high refractive index is small, and the refractive index of the electron-donating material, which has a lower refractive index than the electron-accepting material (MoO3), strongly influences the refractive index of the hole injection layer (111), so the light extraction efficiency is good. That is, by using a volume ratio of MoO3 of the hole injection layer (111) greater than 0 and a concentration of 0.3 or less, a light-emitting device with good light extraction efficiency can be fabricated.

[0443] (Example 2)

[0444] In this embodiment, as an electronic device according to one embodiment of the present invention, an example of fabrication of a light-emitting element different from Example 1 and the characteristics of the light-emitting element are described. In addition, the refractive index of the organic compound used in the hole injection layer (111) and the refractive index of the hole injection layer are described. In addition, details of the device structure are shown in Table 7. The structure and abbreviation of the compound used are shown below. In addition, for other organic compounds, it is recommended to refer to Example 1 described above.

[0445] [Chemical Formula 9]

[0446]

[0447] [Table 7]

[0448]

[0449] [Table 8]

[0450]

[0451] [Table 9]

[0452]

[0453] Measurement of Refractive Index

[0454] The refractive index of the organic compound used in the hole injection layer (111) of comparative light-emitting elements 19 to 22, light-emitting elements 23 to 26, and light-emitting elements 27 to 30 was measured. The measurement of the refractive index was performed in the same manner as in Example 1.

[0455] The results of measuring the refractive index of each film in light with a wavelength of 532 nm are shown in Fig. 19. From Fig. 19, it was found that DBT3P-II, used in comparative light-emitting devices 19 to 22, has the highest refractive index. It was found that 9-[3-(9-phenyl-9H-fluorene-9-yl)phenyl]-9H-carbazole (abbreviated: mCzFLP), used in light-emitting devices 23 to 26, is an organic compound with a low refractive index, with an n Ordinary value of 1.75 or less. In addition, it was found that 4,4'-[bis(9-phenylfluorene-9-yl)]-triphenylamine (abbreviated: FLP2A), used in light-emitting devices 27 to 30, is an organic compound with a low refractive index, with an n Ordinary value of 1.75 or less.

[0456] In addition, from the results of Example 1, the mixed film of mCzFLP or FLP2A and MoO3, which is the hole injection layer (111) of light-emitting elements 23 to 30, is expected to have a refractive index similar to that of each organic compound and a lower refractive index than the mixed film of DBT3P-II and MoO3, which is the hole injection layer (111) of comparative light-emitting elements 19 to 22.

[0457] Fabrication of light-emitting devices

[0458] <<Fabrication of Comparative Light-Emitting Elements 19 to 22>>

[0459] The fabrication process of comparative light-emitting elements 19 to 22 is different from the fabrication process of comparative light-emitting elements 1 to 4 only in the fabrication process of the hole injection layer (111) and the light-emitting layer (130), and the other processes are performed in the same way as comparative light-emitting elements 1 to 4.

[0460] As a hole injection layer (111) on the electrode (101), DBT3P-II and MoO3 were co-deposited with a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of z1 nm. Additionally, the value of z1 is different for each light-emitting element, and the value of z1 for each light-emitting element is the value shown in Table 8.

[0461] Next, as a light-emitting layer (130(1)) on the hole transport layer (112), 4,6 mCz P2Pm, PCCP, and Ir(ppy)3 are co-deposited with a weight ratio (4,6 mCz P2Pm:PCCP:Ir(ppy)3) of 0.5:0.5:0.1 and a thickness of 20 nm, and then as a light-emitting layer (130(2)), a weight ratio (4,6 mCz P2Pm:PCCP:Ir(ppy)3) of 0.8:0.2:0.1 and a thickness of 20 nm are co-deposited. In addition, in the light-emitting layer (130(1)) and the light-emitting layer (130(2)), Ir(ppy)3 is a guest material that exhibits phosphorescent light emission.

[0462] <<Fabrication of light-emitting elements 23 to 26>>

[0463] The fabrication process of light-emitting elements 23 to 26 is different from the fabrication process of comparative light-emitting elements 19 to 22 and the fabrication process of the hole injection layer (111), and other processes are performed in the same way as comparative light-emitting elements 19 to 22.

[0464] As a hole injection layer (111(1)) on the electrode (101), mCzFLP and MoO3 were co-deposited with a weight ratio (mCzFLP:MoO3) of 2:0.5 and a thickness of 35 nm, and then DBT3P-II and MoO3 were co-deposited with a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of z2 nm. In addition, the value of z2 is different for each light-emitting element, and the value of z2 for each light-emitting element is the value shown in Table 9.

[0465] <<Fabrication of light-emitting elements 27 to 30>>

[0466] The fabrication process of light-emitting elements 27 to 30 is different only from the fabrication process of comparative light-emitting elements 19 to 22 and the fabrication process of the hole injection layer (111), and other processes are performed in the same way as comparative light-emitting elements 19 to 22.

[0467] As a hole injection layer (111(1)) on the electrode (101), FLP2A and MoO3 were co-deposited with a weight ratio (FLP2A:MoO3) of 2:0.5 and a thickness of 35 nm, and then DBT3P-II and MoO3 were co-deposited with a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of z2 nm. In addition, the value of z2 is different for each light-emitting element, and the value of z2 for each light-emitting element is the value shown in Table 9.

[0468] Characteristics of light-emitting devices

[0469] Next, the characteristics of the fabricated comparative light-emitting elements 19 to 22 and light-emitting elements 23 to 30 were measured. The measurements were performed in the same manner as in Example 1.

[0470] Among the fabricated light-emitting elements, the current efficiency-luminance characteristics of comparison light-emitting element 19, light-emitting element 23, and light-emitting element 27 are shown in FIG. 20. Also, the current density-voltage characteristics are shown in FIG. 21. Also, the external quantum efficiency-luminance characteristics are shown in FIG. 22. Also, the value of the external quantum efficiency shown in FIG. 22 is the external quantum efficiency when measured from the front direction with respect to the light-emitting element without performing viewing angle correction. Also, as for the organic compound of the hole injection layer (111), comparison light-emitting element 19 uses DBT3P-II, light-emitting element 23 uses mCzFLP, and light-emitting element 27 uses FLP2A, and all parts other than the hole injection layer (111) have the same device structure.

[0471] From FIG. 21, it was found that the comparative light-emitting element 19, light-emitting element 23, and light-emitting element 27 have equivalent current density-voltage characteristics. Therefore, it was found that even if an organic compound with a low refractive index is used in the hole injection layer (111) as in Example 1, good hole injection characteristics are obtained.

[0472] In addition, from FIGS. 20 and 22, it was found that comparative light-emitting elements 19, light-emitting elements 23, and light-emitting elements 27 have a high current efficiency of around 100 cd / A and a high external quantum efficiency exceeding 25%. Furthermore, light-emitting elements 23 and 27, which use mCzFLP and FLP2A, which are organic compounds with a low refractive index, in the hole injection layer (111), showed higher efficiency than comparative light-emitting element 19, which uses DBT3P-II, which is a material with a high refractive index.

[0473] In addition, 25 mA / cm² for comparative light-emitting elements 19, light-emitting element 23, and light-emitting element 27 2The emission spectrum when current is passed at a current density is shown in FIG. 23. As shown in FIG. 23, the emission spectra of comparative light-emitting elements 19, light-emitting elements 23, and light-emitting elements 27 have a peak around 518 nm and can be seen to originate from the emission of Ir(ppy)3, a guest material included in the light-emitting layer (130).

[0474] In addition, 1000 cd / m² of comparative light-emitting elements 19 to 22, and light-emitting elements 23 to 30 2 The device characteristics in the vicinity are shown in Table 10.

[0475] [Table 10]

[0476]

[0477] From the above results, it can be seen that the comparative light-emitting elements 19 to 22 and light-emitting elements 23 to 30 produced in this embodiment exhibit good driving voltage and light-emitting efficiency regardless of the structure of the hole injection layer (111).

[0478] <Relationship between the refractive index of the hole injection layer (111) and the external quantum efficiency>

[0479] In FIG. 24, the relationship between chromaticity x and external quantum efficiency according to the organic material used in each hole injection layer (111) is shown using the values ​​of each element shown in Table 10. In FIG. 24, the values ​​of comparative light-emitting elements 19 to 22 were used for the curve data of "DBT3P-II", the values ​​of light-emitting elements 23 to 26 were used for the curve data of "mCzFLP", and the values ​​of light-emitting elements 27 to 30 were used for the curve data of "FLP2A".

[0480] From FIG. 19, the organic compounds used in the hole injection layer (111) have higher refractive indices in the order of DBT3P-II > mCzFLP > FLP2A. From FIG. 24, it was found that, as in Example 1, the lower the refractive index of the organic compounds used in the hole injection layer (111), the higher the external quantum efficiency. This is because the attenuation of light due to the ebenescent mode is reduced and the light extraction efficiency is improved.

[0481] Above, it was found that by using an organic compound with a low refractive index in the hole injection layer (111), a light-emitting device with good light extraction efficiency is obtained while maintaining hole injection characteristics.

[0482] (Example 3)

[0483] In this embodiment, an example of fabrication of a light-emitting element, which is a type of electronic device according to one embodiment of the present invention, and the characteristics of the light-emitting element are described. In addition, the refractive index of the organic compound used in the hole injection layer and the refractive index of the hole injection layer are described. A cross-sectional view of the device structure fabricated in this embodiment is shown in FIG. 2 (A). In addition, details of the device structure are shown in Tables 11 to 14. Furthermore, the structure and abbreviation of the compound used may be taken into account in the above-described embodiments and examples.

[0484] [Table 11]

[0485]

[0486] [Table 12]

[0487]

[0488] [Table 13]

[0489]

[0490] [Table 14]

[0491]

[0492] Measurement of Refractive Index

[0493] The organic compound used in the hole injection layer (111) of comparative light-emitting elements 31 to 34, light-emitting elements 35 to 38, light-emitting elements 39 to 42, light-emitting elements 43 to 46, and comparative light-emitting elements 47 to 50, and the refractive index of the hole injection layer (111) used in comparative light-emitting elements 31 to 34, light-emitting elements 35 to 38, light-emitting elements 39 to 42, light-emitting elements 43 to 46, and comparative light-emitting elements 47 to 50 were measured. The measurement of the refractive index was performed in the same manner as the method described in Example 1.

[0494] The results of measuring the refractive index of each film in light with a wavelength of 532 nm are shown in FIG. 25. From FIG. 25, it was found that DBT3P-II used in comparative light-emitting elements 31 to 34 had the highest refractive index. It was found that CzC used in light-emitting elements 35 to 38, CzSi used in light-emitting elements 39 to 42, FATPA used in light-emitting elements 43 to 46, and 1,4-di(triphenylsilyl)benzene (abbreviated: UGH-2) used in comparative light-emitting elements 47 to 50 were all organic compounds with very low refractive indices, with an n Ordinary of 1.70 or less.

[0495] In addition, since hole injection properties are required for the hole injection layer (111), it is desirable to have an electron-donating material. The hole injection layer (111) of each light-emitting device using MoO3, which has a high refractive index, as the electron-donating material is expected to have a high refractive index. However, from FIG. 25, it was found that the refractive index of the film in which MoO3, which is the hole injection layer (111) of each light-emitting device, is added to each organic compound is only slightly higher than the refractive index of each organic compound. That is, by using a material having electron-donating properties with a low refractive index in the hole injection layer (111), it was found that a hole injection layer (111) with a low refractive index can be obtained even if a material with a high refractive index is mixed with the electron-donating material.

[0496] Also, from FIG. 25, it was found that the hole injection layer (111) of each light-emitting element has a smaller difference between n Ordinary and n Extraordinary than the film of each organic compound. That is, it was found that the mixed film of MoO3, which is an electron-donating material, and an organic compound has reduced anisotropy compared to the organic compound film.

[0497] In addition, the organic compound CzSi used in the hole injection layer (111) of light-emitting elements 39 to 42, and the organic compound UGH-2 used in the hole injection layer (111) of comparative light-emitting elements 47 to 50, and the mixed film of MoO3 are expected to have the same refractive index as each organic compound, and have a lower refractive index than the mixed film of DBT3P-II and MoO3, which is the hole injection layer (111) of comparative light-emitting elements 1 to 4.

[0498] Fabrication of light-emitting devices

[0499] <<Fabrication of Comparative Light-Emitting Elements 31 to 34>> An ITSO film was formed on a glass substrate as an electrode (101) with a thickness of 70 nm. In addition, the electrode area of ​​the electrode (101) is 4 mm2 It was made (2mm×2mm).

[0500] Next, as a hole injection layer (111) on the electrode (101), 1,3,5-tri-(4-dibenzothiophenyl)-benzene (abbreviated: DBT3P-II) and MoO3 were co-deposited with a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of x3 nm. Additionally, the value of x3 is different for each light-emitting element, and the value of x3 for each light-emitting element is the value shown in Table 13.

[0501] Next, PCCP was deposited on the hole injection layer (111) as a hole transport layer (112) with a thickness of 20 nm.

[0502] Next, as a light-emitting layer (130(1)) on the hole transport layer (112), 4,6 mCz P2Pm, PCCP, and Ir(ppy)3 are co-deposited with a weight ratio (4,6 mCz P2Pm:PCCP:Ir(ppy)3) of 0.5:0.5:0.1 and a thickness of 20 nm, and then as a light-emitting layer (130(2)), a weight ratio (4,6 mCz P2Pm:PCCP:Ir(ppy)3) of 0.8:0.2:0.1 and a thickness of 20 nm are co-deposited. In addition, in the light-emitting layer (130(1)) and the light-emitting layer (130(2)), Ir(ppy)3 is a guest material that exhibits phosphorescent light emission.

[0503] Next, 4,6 mCz P2Pm was co-deposited on the light-emitting layer (130(2)) as a first electron transport layer (118(1)) with a thickness of 20 nm. Subsequently, vasophenanthroline (abbreviated as BPhen) was deposited on the first electron transport layer (118(1)) as a second electron transport layer (118(2)) with a film thickness of 10 nm.

[0504] Next, lithium fluoride (LiF) was deposited on the second electron transport layer (118(2)) as an electron injection layer (119) with a thickness of 1 nm.

[0505] Next, aluminum (Al) was formed as an electrode (102) on the electron injection layer (119) with a thickness of 200 nm.

[0506] Next, comparative light-emitting elements 31 to 34 were sealed in a glove box under a nitrogen atmosphere by fixing a glass substrate for sealing using a sealant for organic EL to a glass substrate on which an organic material was formed. Specifically, a sealant was applied around the organic material on the glass substrate on which the organic material was formed, and this substrate was bonded to the glass substrate for sealing, thereby emitting ultraviolet light with a wavelength of 365 nm at 6 J / cm² 2 The sample was investigated and heat-treated at 80°C for 1 hour. Comparative light-emitting elements 31 to 34 were obtained by the above-described process.

[0507] <<Fabrication of light-emitting elements 35 to 46 and comparative light-emitting elements 47 to 50>>

[0508] The fabrication process of light-emitting elements 35 to 46 and comparative light-emitting elements 47 to 50 differs only in the fabrication process of the hole injection layer (111) from the fabrication process of comparative light-emitting elements 31 to 34, and other processes were performed in the same manner as comparative light-emitting elements 31 to 34. Since the details of the element structure are as shown in Tables 11 to 14, the details of the fabrication method are omitted.

[0509] Characteristics of light-emitting devices

[0510] Next, the characteristics of the fabricated comparative light-emitting elements 31 to 34, light-emitting elements 35 to 46, and comparative light-emitting elements 47 to 50 were measured. The measurements were performed in the same manner as in Example 1.

[0511] Among the fabricated light-emitting elements, the current efficiency-luminance characteristics of comparative light-emitting element 31, light-emitting element 35, light-emitting element 39, light-emitting element 43, and comparative light-emitting element 47 are shown in FIG. 26. The current density-voltage characteristics are also shown in FIG. 27. Additionally, the external quantum efficiency-luminance characteristics are shown in FIG. 28. Furthermore, the value of the external quantum efficiency shown in FIG. 28 is the external quantum efficiency when measured from the front direction with respect to the light-emitting element without performing viewing angle correction. Additionally, regarding the organic compound of the hole injection layer (111), comparative light-emitting element 31 uses DBT3P-II, light-emitting element 35 uses CzC, light-emitting element 39 uses CzSi, light-emitting element 43 uses FATPA, and comparative light-emitting element 47 uses UGH-2, and all parts other than the hole injection layer (111) have the same device structure.

[0512] From FIGS. 26 and 28, it was found that comparative light-emitting elements 31, emitting elements 35, emitting elements 39, emitting elements 43, and comparative light-emitting elements 47 have a high current efficiency exceeding 90 cd / A and a high external quantum efficiency exceeding 25%. Additionally, light-emitting elements 35, emitting elements 39, emitting elements 43, and comparative light-emitting elements 47, which use an organic compound with a low refractive index in the hole injection layer (111), exhibited higher efficiency than comparative light-emitting element 31, which uses DBT3P-II, a material with a high refractive index. This suggests that light attenuation due to evanescent waves is suppressed by using an organic compound with a low refractive index in the hole injection layer (111).

[0513] In addition, from FIG. 27, it was found that comparative light-emitting elements 31, light-emitting elements 35, light-emitting elements 39, and light-emitting elements 43 have equivalent good current density-voltage characteristics. Meanwhile, it was found that comparative light-emitting element 47 has degraded current density-voltage characteristics and low hole injection properties compared to comparative light-emitting elements 31, light-emitting elements 35, light-emitting elements 39, and light-emitting elements 43. This is because UGH-2 does not have electron-donating groups in its molecules. Therefore, it was found that if electron-donating groups are present in the molecules, a hole injection layer (111) having good hole injection properties can be fabricated even if a material with a small refractive index is used in the hole injection layer (111).

[0514] In addition, 25 mA / cm² for comparative light-emitting elements 31, light-emitting elements 35, light-emitting elements 39, light-emitting elements 43, and comparative light-emitting elements 47 2 The emission spectrum when current is passed at a current density is shown in FIG. 29. As shown in FIG. 29, the emission spectra of comparative emission elements 31, emitting elements 35, emitting elements 39, emitting elements 43, and comparative emission elements 47 have a peak around 518 nm and can be seen to originate from the emission of Ir(ppy)3, a guest material included in the emission layer (130).

[0515] In addition, 1000 cd / m² of comparative light-emitting elements 31 to 34, light-emitting elements 35 to 46, and comparative light-emitting elements 47 to 50 2 The device characteristics in the vicinity are shown in Table 15. The external quantum efficiency shown in Table 15 represents the external quantum efficiency after performing viewing angle correction.

[0516] [Table 15]

[0517]

[0518] From the above results, it can be seen that the comparative light-emitting elements 31 to 34, light-emitting elements 35 to 46, and comparative light-emitting elements 47 to 50 fabricated in this embodiment exhibit good driving voltage and light-emitting efficiency regardless of the structure of the hole injection layer (111).

[0519] Reliability of light-emitting devices

[0520] Next, a constant current driving test at 2mA was performed on the comparative light-emitting element 31, light-emitting element 35, light-emitting element 39, light-emitting element 43, and comparative light-emitting element 47. The results are shown in FIG. 30. From FIG. 30, it was found that the reliability of the comparative light-emitting element 31, light-emitting element 35, light-emitting element 39, and light-emitting element 43 is better compared to the comparative light-emitting element 47. In particular, it was found that the reliability of the light-emitting element 43 is good. As described above, it is believed that the organic compound used in the hole injection layer (111) of the comparative light-emitting element 31, light-emitting element 35, light-emitting element 39, and light-emitting element 43 has electron-donating groups within its molecule, and therefore has better hole injection properties compared to UGH-2 used in the comparative light-emitting element 47. Thus, it was found that if the hole injection properties of the hole injection layer (111) are good, the reliability of the light-emitting element is better. Also, in FIG. 30, the reliability test results of comparative light-emitting elements 31, light-emitting elements 35, and light-emitting elements 39 are superimposed.

[0521] <Relationship between the refractive index of the hole injection layer (111) and the external quantum efficiency>

[0522] In FIG. 31, the relationship between chromaticity x and external quantum efficiency according to the organic material used in each hole injection layer (111) is shown using the values ​​of each element shown in Table 15. In FIG. 31, the values ​​of comparative light-emitting elements 31 to 34 were used for the curve data of "DBT3P-II", the values ​​of light-emitting elements 35 to 38 were used for the curve data of "CzC", the values ​​of light-emitting elements 39 to 42 were used for the curve data of "CzSi", the values ​​of light-emitting elements 43 to 46 were used for the curve data of "FATPA", and the values ​​of comparative light-emitting elements 47 to 50 were used for the curve data of "UGH-2".

[0523] From FIG. 25, DBT3P-II, an organic compound used in the hole injection layer (111), has a high refractive index exceeding 1.80, whereas CzC, CzSi, FATPA, and UGH-2 are organic compounds with a low refractive index of 1.70 or less. From FIG. 31, it was found that a light-emitting device using an organic compound with a low refractive index in the hole injection layer (111) has a higher external quantum efficiency than a light-emitting device using DBT3P-II in the hole injection layer (111). This is because the attenuation of light due to the evanescent mode is reduced and the light extraction efficiency is improved.

[0524] Above, it was found that by using either a tetraarylmethane backbone or a tetraarylsilane backbone and an organic compound having an electron-donating group in the hole injection layer (111), a light-emitting device with good light extraction efficiency and good reliability is obtained while maintaining hole injection characteristics.

[0525] (Example 4)

[0526] In this embodiment, an example of fabrication of a light-emitting element, which is a type of electronic device according to one embodiment of the present invention, and the characteristics of the light-emitting element are described. In addition, the refractive index of the organic compound used in the hole injection layer and the refractive index of the hole injection layer are described. A cross-sectional view of the device structure fabricated in this embodiment is shown in FIG. 2 (A). In addition, detailed information on the device structure is shown in Tables 16 and 17. The structure and abbreviation of the compound used are shown below. In addition, for other organic compounds, it is recommended to refer to the above-described examples and embodiments. Furthermore, the light-emitting element shown in this embodiment is composed solely of organic compounds without using a metal oxide in the hole injection layer (111).

[0527] [Chemical Formula 10]

[0528]

[0529] [Table 16]

[0530]

[0531] [Table 17]

[0532]

[0533] Measurement of Refractive Index

[0534] The refractive index of the hole injection layer (111) of comparative light-emitting elements 51 to 54, comparative light-emitting elements 55 to 58, light-emitting elements 59 to 62, and light-emitting elements 63 to 66 was measured. The measurement of the refractive index was performed in the same manner as described in Example 1. The values ​​of the refractive index (n Ordinary) of each film in light with a wavelength of 633 nm are shown in Table 18.

[0535] [Table 18]

[0536]

[0537] From Table 18, it was found that the mixed film of N,N,N',N'-tetra-naphthalene-2-yl-benzidine (abbreviated: β-TNB) and p-dopant (purchased from Analysis Atelier Corporation), used in comparative light-emitting devices 51 to 54, and the mixed film of NPB and p-dopant, used in comparative light-emitting devices 55 to 58, had a refractive index greater than 1.75 and had a high refractive index. On the other hand, it was found that the mixed film of BPAFLP and p-dopant, used in light-emitting devices 59 to 62, and the mixed film of TAPC and p-dopant, used in light-emitting devices 63 to 66, had a refractive index lower than 1.75 and had a low refractive index.

[0538] Fabrication of light-emitting devices

[0539] <<Fabrication of Comparative Light Emitting Devices 51 to 54>> An ITSO film was formed on a glass substrate as an electrode (101) with a thickness of 70 nm. In addition, the electrode area of ​​the electrode (101) is 4 mm 2 It was made (2mm×2mm).

[0540] Next, as a hole injection layer (111) on the electrode (101), β-TNB and p-dopant were co-deposited with a weight ratio (β-TNB:p-dopant) of 1:0.01 and a thickness of 60 nm.

[0541] Next, PCBBiF was deposited on the hole injection layer (111) as a hole transport layer (112) with a thickness of z1 nm. Also, the value of z1 is different for each light-emitting element, and the value of z1 for each light-emitting element is the value shown in Table 17.

[0542] Next, as a light-emitting layer (130(1)) on the hole transport layer (112), 2mDBTBPDBq-II, PCBBiF, and Ir(dppm)2(acac) are co-deposited with a weight ratio (2mDBTBPDBq-II:PCBBiF:Ir(dppm)2(acac)) of 0.7:0.3:0.06 and a thickness of 20 nm, and then as a light-emitting layer (130(2)), a weight ratio (2mDBTBPDBq-II:PCBBiF:Ir(dppm)2(acac)) of 0.8:0.2:0.06 and a thickness of 20 nm are co-deposited. In addition, in the light-emitting layer (130(1)) and the light-emitting layer (130(2)), Ir(dppm)2(acac) is a guest material that exhibits phosphorescent light emission.

[0543] Next, 2mDBTBPDBq-II was co-deposited on the light-emitting layer (130(2)) as a first electron transport layer (118(1)) with a thickness of 20 nm. Subsequently, 2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen) was deposited on the first electron transport layer (118(1)) as a second electron transport layer (118(2)) with a film thickness of 20 nm.

[0544] Next, lithium fluoride (LiF) was deposited on the second electron transport layer (118(2)) as an electron injection layer (119) with a thickness of 1 nm.

[0545] Next, aluminum (Al) was formed as an electrode (102) on the electron injection layer (119) with a thickness of 200 nm.

[0546] Next, comparative light-emitting elements 51 to 54 were sealed in a glove box under a nitrogen atmosphere by fixing a glass substrate for sealing using a sealant for organic EL to a glass substrate on which an organic material was formed. Specifically, a sealant was applied around the organic material on the glass substrate on which the organic material was formed, and this substrate was bonded to the glass substrate for sealing, thereby emitting ultraviolet light with a wavelength of 365 nm at 6 J / cm² 2 The sample was investigated and heat-treated at 80°C for 1 hour. Comparative light-emitting elements 51 to 54 were obtained by the above-described process.

[0547] <<Fabrication of Comparative Light-emitting Devices 55 to 58 and Light-emitting Devices 59 to 66>>

[0548] The fabrication process of comparative light-emitting elements 55 to 58 and light-emitting elements 59 to 66 differs only in the fabrication process of the hole injection layer (111) from the fabrication process of comparative light-emitting elements 51 to 54, and other processes were performed in the same manner as comparative light-emitting elements 51 to 54. Since the details of the device structure are as shown in Tables 16 and 17, the details of the fabrication method are omitted.

[0549] Characteristics of light-emitting devices

[0550] Next, the characteristics of the fabricated comparative light-emitting elements 51 to 58 and light-emitting elements 59 to 66 were measured. The measurements were performed in the same manner as in Example 1. 1000 cd / m² 2 The characteristics of each element in the vicinity are shown in Table 19. The external quantum efficiency shown in Table 19 represents the external quantum efficiency before performing viewing angle correction.

[0551] [Table 19]

[0552]

[0553] From the above results, it can be seen that the comparative light-emitting elements 51 to 58 and light-emitting elements 59 to 66 produced in this embodiment exhibit good driving voltage and light-emitting efficiency regardless of the structure of the hole injection layer (111).

[0554] <Relationship between the refractive index of the hole injection layer (111) and the external quantum efficiency>

[0555] In FIG. 32, the relationship between chromaticity y and external quantum efficiency according to the organic material used in each hole injection layer (111) is shown using the values ​​of each element shown in Table 19. In FIG. 32, the values ​​of comparative light-emitting elements 51 to 54 were used for the curve data of "β-TNB", the values ​​of comparative light-emitting elements 55 to 58 were used for the curve data of "NPB", the values ​​of light-emitting elements 59 to 62 were used for the curve data of "BPAFLP", and the values ​​of light-emitting elements 63 to 66 were used for the curve data of "TAPC".

[0556] From Table 18, when β-TNB and NPB are used in the hole injection layer (111), the refractive index of the hole injection layer (111) is a high refractive index exceeding 1.75, but when BPAFLP and TAPC are used, the refractive index of the hole injection layer (111) is a low refractive index of 1.75 or less. From FIG. 32, for example, when comparing the external quantum efficiency of each light-emitting element around a y-chroma of 0.435, it was found that the light-emitting element having a hole injection layer (111) with a low refractive index has a higher external quantum efficiency. Therefore, at the same chroma, it was found that the light-emitting element having a hole injection layer (111) with a low refractive index has better light-emitting efficiency. This is because the attenuation of light due to the evanescent mode is reduced and the light extraction efficiency is improved.

[0557] (Reference Example 1)

[0558] In this reference example, the synthesis method of Ir(pbi-diBuCNp)3 used in Example 1 is described.

[0559] <Step 1; Synthesis of 4-amino-3,5-diisobutylbenzonitrile>

[0560] 52 g (280 mmol) of 4-amino-3,5-dichlorobenzonitrile, 125 g (1226 mmol) of isobutylboronic acid, 260 g (1226 mmol) of tripotassium phosphate, 5.4 g (13.1 mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S-phos), and 1500 mL of toluene were placed in a 3000 mL three-necked flask, nitrogen was applied to the flask, and the mixture was degassed by stirring under reduced pressure. After degassing, 4.8 g (5.2 mmol) of tris(dibenzylideneacetone)dipalladium (O) was added, and the mixture was stirred for 12 hours at 130°C under a nitrogen stream. Toluene was added to the obtained reaction solution, and suction filtration was performed using a filtration aid layered in the order of Celite (Wako Pure Chemical Industries, Ltd., Catalog No.: 531-16855), Florisil (Wako Pure Chemical Industries, Ltd., Catalog No.: 540-00135), and aluminum oxide. The obtained filtrate was concentrated to obtain an oily substance. The obtained oily substance was purified by silica column chromatography. Toluene was used as the developing solvent. The obtained fraction was concentrated to obtain 61 g of yellow oily substance with a yield of 95%. Nuclear magnetic resonance (NMR) confirmed that the obtained yellow oily substance was 4-amino-3,5-diisobutylbenzonitrile. The synthesis scheme for Step 1 is shown in the following equation (a-1).

[0561] [Chemical Formula 11]

[0562]

[0563] <Step 2; Synthesis of 4-[N-(2-nitrophenyl)amino]-3,5-diisobutylbenzonitrile>

[0564] 30 g (131 mmol) of 4-amino-3,5-diisobutylbenzonitrile synthesized in Step 1, 86 g (263 mmol) of cesium carbonate, 380 mL of dimethyl sulfoxide (DMSO), and 19 g (131 mmol) of 2-fluoronitrobenzene were placed in a 1000 mL three-necked flask and stirred at 120 °C for 20 hours under a nitrogen stream. After the specified time had elapsed, the reaction solution was extracted using chloroform to obtain a crude product. The obtained crude product was purified by silica column chromatography. A hexane:ethyl acetate ratio of 7:1 was used as the developing solvent. The resulting fraction was concentrated to obtain an orange solid. Hexane was added to the obtained solid and filtered by suction to obtain 16 g of a yellow solid with a yield of 35%. It was confirmed by nuclear magnetic resonance (NMR) that the yellow solid obtained was 4-[N-(2-nitrophenyl)amino]-3,5-diisobutylbenzonitrile. The synthesis scheme for step 2 is shown in the following formula (a-2).

[0565] [Chemical Formula 12]

[0566]

[0567] <Step 3; Synthesis of 4-[N-(2-aminophenyl)amino]-3,5-diisobutylbenzonitrile>

[0568] 21 g (60.0 mmol) of 4-[N-(2-nitrophenyl)amino]-3,5-diisobutylbenzonitrile synthesized in Step 2, 11 mL (0.6 mol) of water, and 780 mL of ethanol were placed in a 2000 mL three-necked flask and stirred. 57 g (0.3 mol) of tin(II) chloride was added to this mixture, and the mixture was stirred for 7.5 hours at 80°C under a nitrogen stream. After the specified time had elapsed, the mixture was poured into 400 mL of a 2 M aqueous sodium hydroxide solution and stirred at room temperature for 16 hours. The precipitated precipitate was removed by suction filtration, and the filtrate was obtained by washing with chloroform. The obtained filtrate was extracted using chloroform. Subsequently, the extracted solution was concentrated to obtain 20 g of a white solid with a yield of 100%. It was confirmed by nuclear magnetic resonance (NMR) that the white solid obtained was 4-[N-(2-aminophenyl)amino]-3,5-diisobutylbenzonitrile. The synthesis scheme for step 3 is shown in the following formula (a-3).

[0569] [Chemical Formula 13]

[0570]

[0571] <Step 4; Synthesis of 1-(4-cyano-2,6-diisobutylphenyl)-2-phenyl-1H-benzimidazole (abbreviation: Hpbi-diBuCNp)>

[0572] 20 g (60.0 mmol) of 4-[N-(2-aminophenyl)amino]-3,5-diisobutylbenzonitrile synthesized in Step 3, 200 mL of acetonitrile, and 6.4 g (60.0 mmol) of benzaldehyde were placed in a 1000 mL branched flask and stirred at 100°C for 1 hour. 100 mg (0.60 mmol) of iron(III) chloride was added to this mixture and stirred at 100°C for 24 hours. After the specified time had elapsed, the reaction solution was extracted using chloroform to obtain an oil phase. Toluene was added to the obtained oil phase, and the mixture was filtered by suction through a filtration aid layered in the order of Celite / Florisil / aluminum oxide. The obtained filtrate was concentrated to obtain an oil phase. The obtained oil phase was purified by silica column chromatography. Toluene was used as the developing solvent. The obtained fraction was concentrated to obtain a solid. This solid was recrystallized using ethylhexane acetate, and the target white solid was obtained in a yield of 4.3 g with a yield of 18%. Nuclear magnetic resonance (NMR) confirmed that the obtained white solid was 1-(4-cyano-2,6-diisobutylphenyl)-2-phenyl-1H-benzimidazole (abbreviated: Hpbi-diBuCNp). The synthesis scheme for Step 4 is shown in the following formula (a-4).

[0573] [Chemical Formula 14]

[0574]

[0575] <Step 5; Tris{2-[1-(4-cyano-2,6-diisobutylphenyl)-1H-benzimidazole-2-yl-κ N 3 ]phenyl-κ C Synthesis of Iridium(III) (abbreviation: Ir(pbi-diBuCNp)3)

[0576] 1.8 g (4.4 mmol) of 1-(4-cyano-2,6-diisobutylphenyl)-2-phenyl-1H-benzimidazole (abbreviated: Hpbi-diBuCNp) synthesized in Step 4 and 0.43 g (0.88 mmol) of tris(acetylacetonato)iridium(III) were placed in a reaction vessel equipped with a three-way stopcock and heated at 250°C for 39 hours. Toluene was added to the resulting reaction mixture to remove insoluble matter. The resulting filtrate was concentrated to obtain a solid. The obtained solid was purified by silica column chromatography (neutral silica). Toluene was used as the developing solvent. The resulting fraction was concentrated to obtain a solid. The obtained solid was recrystallized using ethylhexane acetate to obtain 0.26 g of a yellow solid with a yield of 21%. The synthesis scheme is shown in the following equation (a-5).

[0577] [Chemical Formula 15]

[0578]

[0579] Proton of the yellow solid obtained above ( 1 H) was measured by nuclear magnetic resonance (NMR). From the measurement results, it was found that Ir(pbi-diBuCNp)3 (a mixture of the fac isomer and the mer isomer) was obtained in this reference example. Also 1 From H-NMR, it was confirmed that it is a mixture of isomers of the fac isomer and the mer isomer. It was found that the ratio of isomers was fac isomer:mer isomer = 3:2. Explanation of the symbols

[0580] 10: Substrate, 11: Electrode, 12: Electrode, 15: Substrate, 20: Organic semiconductor layer, 30: Carrier transport layer, 40: Functional layer, 50: Electronic device, 100: EL layer, 101: Electrode, 102: Electrode, 106: Emitting unit, 108: Emitting unit, 110: Emitting unit, 111: Hole injection layer, 112: Hole transport layer, 113: Electron transport layer, 114: Electron injection layer, 115: Charge generation layer, 116: Hole injection layer, 117: Hole transport layer, 118: Electron transport layer, 119: Electron injection layer, 120: Emitting layer, 121: Guest material, 122: Host material, 130: Emitting layer, 131: Guest material, 131_1: Organic compound, 131_2: Organic Compound, 132: Host material, 134: Emitting region, 140: Emitting layer, 141: Guest material, 142: Host material, 142_1: Organic compound, 142_2: Organic compound, 150: Emitting element, 170: Emitting layer, 200: Substrate, 250: Emitting element, 252: Emitting element, 601: Source-side driving circuit, 602: Pixel portion, 603: Gate-side driving circuit, 604: Sealing substrate, 605: Sealing material, 607: Space, 608: Wiring, 610: Device substrate, 611: Switching TFT, 612: Current control TFT, 613: Electrode, 614: Insulator, 616: EL layer, 617: Electrode, 618: Emitting element, 623: n-channel TFT, 624: p-channel TFT, 900: Portable information terminal, 901: Housing, 902: Housing, 903: Display, 905: Hinge, 910: Portable information terminal, 911: Housing, 912: Display, 913: Operation button, 914: External connection port, 915: Speaker, 916: Microphone, 917: Camera, 920: Camera, 921: Housing, 922: Display, 923: Operation button, 924: Shutter button, 926: Lens, 1001: Substrate, 1002: Underlay insulating film, 1003: Gate insulating film, 1006: Gate electrode, 1007: Gate electrode,1008: Gate electrode, 1020: Interlayer insulating film, 1021: Interlayer insulating film, 1022: Electrode, 1024B: Electrode, 1024G: Electrode, 1024R: Electrode, 1024W: Electrode, 1025B: Bottom electrode, 1025G: Bottom electrode, 1025R: Bottom electrode, 1025W: Bottom electrode, 1026: Barrier, 1028: EL layer, 1029: Electrode, 1031: Sealing substrate, 1032: Material, 1033: Substrate, 1034B: Coloring layer, 1034G: Coloring layer, 1034R: Coloring layer, 1036: Overcoat layer, 1037: Interlayer insulating film, 1040: Pixel portion, 1041: Driving circuit portion, 1042: Peripheral part, 3054: Display unit, 3500: Multifunction terminal, 3502: Housing, 3504: Display unit, 3506: Camera, 3508: Lighting, 3600: Light, 3602: Housing, 3608: Lighting, 3610: Speaker, 8501: Lighting device, 8502: Lighting device, 8503: Lighting device, 8504: Lighting device, 9000: Housing, 9001: Display unit, 9003: Speaker, 9005: Operation key, 9006: Connection terminal, 9007: Sensor, 9008: Microphone, 9055: Hinge, 9200: Portable information terminal, 9201: Portable information terminal, 9202: Portable information terminal,

Claims

Claim 1 An electronic device having a first electrode, a second electrode, a first layer, and a second layer, wherein the first layer is provided between the first electrode and the second layer, the second layer is provided between the first layer and the second electrode, the first layer has a first material and a first organic compound, the first material has electron accepting properties, and the refractive index when the first organic compound is formed into a thin film is 1 or greater and 1.75 or less. Claim 2 An electronic device having a first layer between a first electrode and a second electrode, wherein the first layer has a first organic compound and a first material, wherein the first organic compound has a first framework and an electron-donating framework, and the first framework is a tetraarylmethane framework or a tetraarylsilane framework. Claim 3 An electronic device having a first layer, a second layer, and a third layer between a first electrode and a second electrode, wherein the first layer is provided between the first electrode and the second layer, the second layer is provided between the first layer and the third layer, the first layer has a first material and a first organic compound, the first material has electron accepting properties, the third layer has a function of emitting or absorbing light, the refractive index of the first layer is lower than both the refractive index of the second layer and the refractive index of the third layer, and the refractive index when the first organic compound is formed as a thin film is 1 or greater and 1.75 or less. Claim 4 An electronic device according to claim 2, wherein the refractive index of the first layer is 1 or greater and 1.75 or less. Claim 5 An electronic device according to claim 2, wherein the aryl groups in the tetraarylmethane backbone and the tetraarylsilane backbone are each independently substituted or unsubstituted aryl groups having 6 to 13 carbon atoms, and furthermore, the aryl groups may be bonded to each other to form a ring. Claim 6 An electronic device according to claim 5, wherein each of the aryl groups is an independently substituted or unsubstituted phenyl group, and furthermore, the phenyl groups may be bonded to each other to form a ring. Claim 7 An electronic device according to claim 2, wherein the electron-donating framework comprises at least one of a pyrrole framework, an aromatic amine framework, an acridine framework, and an azepine framework. Claim 8 An electronic device according to claim 2, wherein the glass transition point (Tg) of the first organic compound is 100°C or higher. Claim 9 An electronic device according to claim 1 or 2, wherein the refractive index of the first layer is lower than the refractive index of the second layer. Claim 10 An electronic device according to claim 1 or 3, wherein the first organic compound has electron-donating properties. Claim 11 In claim 3, the third layer is an electronic device in contact with the second layer. Claim 12 An electronic device according to any one of claims 1 to 3, wherein the first layer is in contact with the second layer. Claim 13 An electronic device according to any one of claims 1 to 3, wherein the refractive index of the first layer is lower than the refractive index of the first electrode. Claim 14 An electronic device according to any one of claims 1 to 3, wherein the volume ratio of the first substance to the first organic compound is 0.01 or more and 0.3 or less. Claim 15 An electronic device according to any one of claims 1 to 3, wherein the first material comprises any one of titanium oxide, vanadium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, and silver oxide. Claim 16 An electronic device according to any one of claims 1 to 3, wherein the first material is any one of TCNQ, F4TCNQ, and F6TCNNQ. Claim 17 An electronic device according to any one of claims 1 to 3, wherein the first electrode is a positive electrode and the second electrode is a negative electrode. Claim 18 An electronic device according to any one of claims 1 to 3, wherein the second layer has a light-emitting function. Claim 19 An electronic device according to any one of claims 1 to 3, wherein the second layer has a photoelectric conversion function. Claim 20 A display device having at least one of an electronic device described in any one of claims 1 to 3, a color filter, and a transistor. Claim 21 An electronic device having at least one of a display device described in claim 20, a housing, and a touch sensor. Claim 22 A lighting device having at least one of an electronic device described in any one of claims 1 to 3, a housing, and a touch sensor.

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