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

Abstract

Provided is an electronic device having high light extraction efficiency and light trapping effect. One embodiment of the present invention is an electronic device comprising: a first layer, a second layer, and a third layer between a first electrode and a second electrode, the first layer being provided between the first electrode and the second layer, the second layer being provided between the first layer and the third layer, and the third layer being provided between the first electrode and the second electrode; the first layer contains a first substance having electron-receiving properties and a first organic compound, the third layer has a function of emitting or absorbing light, the refractive index of the first layer is lower than the refractive index of the second layer, the refractive index of the first layer is lower than the refractive index of the third layer, and the refractive index of the second layer is lower than the refractive index of the third layer. When the first organic compound is a thin film, the refractive index of the first organic compound with respect to light having a wavelength of 532 nm is 1-1.75, the first organic compound has electron donating properties, and the first organic compound contains a non-mutual hydrocarbon.

Description

This application is a divisional application of the Chinese patent application titled “Electronic devices, light-emitting devices, electronic devices and lighting devices” with national application number 201880029951.8 after the PCT international application with international application number PCT / IB2018 / 053276 and international application date May 11, 2018 entered the Chinese stage. Technical Field

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

[0002] Note that one embodiment of the present invention is not limited to the above-mentioned technical field. One embodiment of the present invention relates to an object, a method, or a manufacturing method. In addition, the present invention relates to a process 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 for manufacturing the same. Background Art

[0003] Light-emitting elements (organic EL elements) and organic solar cells that utilize electroluminescence (EL) using organic compounds are being put into practical use. In the basic structure of these electronic devices, a semiconductor layer containing an organic compound is sandwiched between a pair of electrodes.

[0004] This electronic device is lightweight, flexible, and highly designed. Research and development of this organic semiconductor element is becoming increasingly popular due to various advantages such as the ability to adopt a coating process. In particular, the light-emitting element is a self-luminous element. When used in pixels of a display, it has advantages such as high visibility and no need for backlight, so it is preferred as a flat panel display element.

[0005] Such electronic devices mainly have an organic semiconductor layer formed of an organic compound in a thin film. The organic compound and the layer structure have a great influence on the organic semiconductor element, so the selection of the organic compound and the layer structure is important. In addition, in electronic devices that emit or absorb light, such as organic solar cells and organic EL elements, a structure with high light extraction efficiency and light trapping effect is important.

[0006] Various methods have been proposed to improve the light extraction efficiency of an organic EL element. For example, in Patent Document 1, the light extraction efficiency is improved by forming a concavo-convex shape in a part of an electrode and an EL layer. [Prior technical literature] [Patent Document]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2013-033706 Summary of the invention Technical problem to be solved by the invention

[0008] In light-emitting elements such as organic EL elements, as a method for improving light extraction efficiency, there is a method of adjusting the refractive index between the substrate and the electrode and / or between the electrode and the EL layer. However, when a layer for adjusting the refractive index is used in an organic EL element, there is a problem that the process becomes complicated. Therefore, it is necessary to develop a layer and a layer structure that can control the refractive index while having the function of an EL layer. In addition, in organic solar cells, it is necessary to develop a layer and a layer structure with a high light trapping effect.

[0009] In view of the above problems, one of the objects of one embodiment of the present invention is to provide an electronic device with high light extraction efficiency. In addition, one of the objects of one embodiment of the present invention is to provide an electronic device including a layer with a low refractive index. In addition, one of the objects of one embodiment of the present invention is to provide an electronic device with a low driving voltage. In addition, one of the objects of one embodiment of the present invention is to provide an electronic device with reduced power consumption. In addition, one of the objects of one embodiment of the present invention is to provide an electronic device with high reliability. In addition, one of the objects of one embodiment of the present invention is to provide an electronic device with high luminous efficiency. In addition, one of the objects of one embodiment of the present invention is to provide a novel electronic device. In addition, one of the objects of one embodiment of the present invention is to provide an electronic device with a high light trapping effect. In addition, one of the objects of one embodiment of the present invention is to provide a novel semiconductor device.

[0010] Note that the description of the above-mentioned objects does not prevent the existence of other objects. Note that one embodiment of the present invention does not necessarily need to achieve all of the above-mentioned objects. Objects other than the above-mentioned objects can be known and derived from the description of the specification and the like. Solutions to technical problems

[0011] One embodiment of the present invention is an electronic device, comprising: a first layer and a second layer between a first electrode and a second electrode; and a first layer between the first electrode and the second layer, wherein the first layer contains a first organic compound and a first substance, the refractive index of the thin film of the first organic compound is greater than 1 and less than 1.75, the first substance has an electron-accepting property, and the second layer has a function of emitting or absorbing light.

[0012] Another embodiment of the present invention is an electronic device, comprising: a first layer between a first electrode and a second electrode, wherein the first layer comprises a first organic compound and a first substance, the first organic compound has a first skeleton and an electron donating skeleton, and the first skeleton is a tetraarylmethane skeleton or a tetraarylsilane skeleton.

[0013] In the above structure, the refractive index of the first layer is preferably greater than or equal to 1 and less than or equal to 1.75. With this structure, the light extraction efficiency and light trapping effect of the electronic device can be improved.

[0014] In the above structure, it is preferred that the aryl groups of the tetraarylmethane skeleton and the tetraarylsilane skeleton are independently substituted or unsubstituted aryl groups having 6 to 13 carbon atoms. More preferably, the aryl group is a substituted or unsubstituted phenyl group. By having this structure, an organic compound having a low refractive index and good carrier transport properties can be obtained. Note that the aryl groups or phenyl groups can be bonded to each other to form a ring.

[0015] In the above structure, the electron donating skeleton preferably has any one of a pyrrole skeleton, an aromatic amine skeleton, an acridine skeleton, and an azapine skeleton. By having this structure, the driving voltage of the electronic device can be reduced.

[0016] In the above structure, the glass transition point (Tg) of the first organic compound is preferably not less than 100° C. With this structure, an electronic device having high heat resistance can be obtained.

[0017] In the above structure, the refractive index of the first layer is preferably lower than the refractive index of the second layer. With this structure, the light extraction efficiency and light trapping effect of the electronic device can be improved.

[0018] Another embodiment of the present invention is an electronic device, comprising: a first layer, a second layer and a third layer between a first electrode and a second electrode; the first layer between the first electrode and the second layer; and the second layer between the first layer and the third layer, wherein the first layer contains a first organic compound and a first substance, the refractive index of the thin film of the first organic compound is greater than 1 and less than 1.75, the first substance has an electron accepting property, the third layer has a function of emitting or absorbing light, the refractive index of the first layer is lower than the refractive index of the second layer, and the refractive index of the first layer is lower than the refractive index of the third layer.

[0019] In the above structure, the first organic compound preferably has an electron donating property. With this structure, an electronic device having excellent carrier transport properties can be obtained.

[0020] In the above structure, the first layer is preferably in contact with the second layer, and the second layer is more preferably in contact with the third layer. With this structure, the refractive index step of each layer can be suppressed, thereby improving the light extraction efficiency and light trapping effect of the electronic device.

[0021] In the above structure, the refractive index of the first layer is preferably lower than the refractive index of the first electrode. With this structure, the light extraction efficiency and light trapping effect of the electronic device can be improved.

[0022] In the above structure, the volume ratio of the first substance to the first organic compound in the first layer is preferably 0.01 to 0.3. With this structure, the light extraction efficiency and light trapping effect of the electronic device can be improved.

[0023] In the above structure, the first substance preferably 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. With this structure, an electronic device with good carrier transport properties can be obtained.

[0024] In the above structure, the first substance is preferably any one of 7,7,8,8-tetracyanoquinodimethane (abbreviated as TCNQ), 7,7,8,8-tetracyano-2,3,5,6-tetrafluoro-quinodimethane (abbreviated as F4TCNQ) and 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated as F6TCNNQ). By having this structure, an electronic device with good carrier transport properties can be obtained.

[0025] In the above structure, the electronic device is preferably an organic EL element or a solar cell.

[0026] In addition, one embodiment of the present invention is an electronic device, which includes: a light-emitting element having the above-mentioned structure; and at least one of a housing and a touch sensor. In addition, one embodiment of the present invention is a lighting device, which includes: an electronic device having each of the above-mentioned structures; and at least one of a housing, a connecting terminal and a protective cover. In addition, one 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. Therefore, the light-emitting device in this specification refers to an image display device or a light source (including a lighting device). In addition, the following display module is also a mode of the present invention: a display module in which a connector such as an FPC (Flexible Printed Circuit) or a TCP (Tape Carrier Package) is installed in the light-emitting element; a display module in which a printed circuit board is provided in the TCP end; or a display module in which an IC (integrated circuit) is directly mounted on an electronic device by a COG (Chip On Glass) method. Effects of the Invention

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

[0028] Note that the description of these effects does not prevent the existence of other effects. Note that one embodiment of the present invention does not necessarily need to have all of the above effects. Note that effects other than the above effects can be known and derived from the description of the specification, drawings, claims, etc. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following description, and its mode and details can be transformed into various forms without departing from the purpose and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the contents recorded in the embodiments shown below.

[0031] In addition, for ease of understanding, the position, size, range, etc. of each structure shown in the drawings and the like may not represent its actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings and the like.

[0032] In addition, in this specification, for the sake of convenience, ordinal numbers such as first and second are added, but they do not sometimes indicate the order of processes or the order of stacking. Therefore, for example, "first" can be appropriately replaced with "second" or "third" for description. In addition, the ordinal numbers recorded in this specification and the like are sometimes inconsistent with the ordinal numbers used to specify one embodiment of the present invention.

[0033] Note that in this specification and the like, when components of the invention are described using drawings, reference numerals may be used in common to represent the same components in different drawings.

[0034] In addition, in this specification, "film" and "layer" may be interchanged. For example, "conductive layer" may be referred to as "conductive film" in some cases. Also, "insulating film" may be referred to as "insulating layer" in some cases.

[0035] In addition, as the refractive index n, there are n Ordinary, which is the refractive index of ordinary light, n Extraordinary, which is the refractive index of extraordinary light, and n Average, which is the average value of the two. In this specification, etc., when simply recorded as "refractive index", the "refractive index" can be regarded as n Average when anisotropy analysis is not performed, and the "refractive index" can be regarded as n Ordinary when anisotropy analysis is performed. In addition, anisotropy refers to the difference between n Ordinary and n Extraordinary. Note that the value obtained by dividing the sum of twice the value of n Ordinary and the value of n Extraordinary by 3 is n Average.

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

[0037] (Implementation Method 1) In this embodiment, refer to Figure 1 An electronic device according to one embodiment of the present invention will be described.

[0038] <Structural Example 1 of Electronic Device> The electronic device 50 includes 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 includes at least a carrier transport layer 30 and a functional layer 40. Note that the organic semiconductor layer 20 may include a plurality of functional layers.

[0039] The functional layer 40 of the electronic device 50 preferably has a function of absorbing or emitting light. When the light generated by the functional layer 40 is extracted from the electrode 11 side, the light passes through the electrode 11 and the carrier transport layer 30 after passing through the substrate 10. In addition, when the light entering the organic semiconductor layer 20 from the electrode 11 side is absorbed by the functional layer 40, the light passes through the electrode 11 and the carrier transport layer 30 after passing through the substrate 10. In order for the light generated by the functional layer 40 to be efficiently extracted or the light to be efficiently absorbed by the functional layer 40, it is preferred that the light attenuated in the electrode 11 and the carrier transport layer 30 is small.

[0040] However, in the electronic device 50, light decays in the organic semiconductor layer 20 in a decay mode called an evanescent mode. For example, when light emission occurs in the functional layer 40, the light generated by the functional layer 40 decays in the evanescent mode while passing through the electrode 11 or being reflected by the electrode 11.

[0041] Here, when a layer having a low refractive index is present among the layers through which light passes, attenuation of the light is reduced. Figure 1 In the embodiment, by using a layer having a low refractive index as the carrier transport layer 30, attenuated light can be suppressed.

[0042] However, in many cases, the carrier transport layer 30 is required to have carrier transport properties or carrier injection properties. Therefore, the carrier transport layer 30 uses a carrier accepting or carrier supplying substance. Because the carrier accepting or carrier supplying substance is mostly a material with a high refractive index, the refractive index of the carrier transport layer 30 becomes high. That is, it is difficult to obtain a layer with a carrier transport property and a low refractive index. In addition, in the case where the carrier accepting or carrier supplying substance is an organic compound, when a saturated cyclic compound such as a cyclohexane skeleton is present in the structure of the organic compound, the refractive index decreases, but there are problems with heat resistance.

[0043] Here, the inventors found that by mixing an organic compound with a low refractive index into the carrier transport layer 30, a layer with a carrier transport property and a low refractive index can be manufactured even if a substance with a high refractive index and electron accepting property is used. In addition, the inventors found that by mixing an organic compound having an electron donating group and any one of a tetraarylmethane skeleton and a tetraarylsilane skeleton into the carrier transport layer 30, a layer with a carrier transport property and a low refractive index can be manufactured even if a substance with a high refractive index and electron accepting property is used. Furthermore, the inventors found that the organic compound has high heat resistance.

[0044] The refractive index of the low-refractive-index organic compound is preferably 1 to 1.75, more preferably 1 to 1.73, and further preferably 1.70 or less. With this structure, a good electronic device with reduced attenuation of light can be obtained.

[0045] The refractive index of the organic compound having an electron donating group and any one of the tetraarylmethane skeleton and the tetraarylsilane skeleton is preferably 1 to 1.75, more preferably 1 to 1.73, and further preferably 1.70 or less. With this structure, an electronic device with reduced attenuation of light and high light extraction efficiency can be obtained.

[0046] <Structural Example 2 of Electronic Device> Hereinafter, a light emitting element which is an example of an electronic device according to one embodiment of the present invention will be described with reference to FIG. 2 .

[0047] Figure 2A It is a schematic cross-sectional view of a light emitting element 150 according to one embodiment of the present invention.

[0048] The light-emitting element 150 includes a substrate 200 and a substrate 210 , includes a pair of electrodes (electrode 101 and electrode 102 ) between the substrate 200 and the substrate 210 , and includes an EL layer 100 provided between the pair of electrodes. The EL layer 100 includes at least a light-emitting layer 130 .

[0049] in addition, Figure 2A The EL layer 100 shown includes 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 .

[0050] Note that although the electrode 101 of a pair of electrodes is described as an anode and the electrode 102 is described as a cathode in this embodiment, the structure of the light-emitting element 150 is not limited to this. That is, the electrode 101 may be used as a cathode and the electrode 102 may be used as an anode, and the layers between the electrodes may be stacked in reverse order. In other words, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 130, the electron transport layer 118, and the electron injection layer 119 may be stacked in order from the anode side.

[0051] In addition, although in this embodiment Figure 2A The electrode 101 (anode) in the embodiment is described as the light extraction side, but the structure of the light emitting element 150 is not limited to this. That is, the light extraction side can also be used as the electrode 102 (cathode) side, and light can be extracted from both the electrode 102 and the electrode 102.

[0052] Note that the structure of the EL layer 100 is not limited to Figure 2A The structure shown only needs to include the light-emitting layer 130, and may include or exclude the hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119. In addition, the EL layer 100 may also include a functional layer having the following functions: a function of reducing the injection barrier of holes or electrons; a function of improving the transportability of holes or electrons; a function of hindering the transportability of holes or electrons; a function of suppressing the quenching phenomenon caused by the electrode; or a function of suppressing the diffusion of excitons, etc. The functional layer may be a single layer or a structure in which a plurality of layers are stacked.

[0053] Figure 2B It is shown Figure 2A FIG. 1 is a schematic cross-sectional view of an example of the light emitting layer 130 shown. Figure 2B The light emitting layer 130 shown may include a guest material 131 and a host material 132 .

[0054] In order to efficiently obtain light from the light emitting element 150, the light emitting element 150 preferably has high light extraction efficiency. However, as described above, the light extraction efficiency of the organic EL element is reduced in a decay mode called an evanescent mode. For example, in the light emitting element 150, the light generated by the light emitting layer 130 is decayed in an evanescent mode when passing through the electrode 101 or reflected by the electrode 101.

[0055] In order to reduce the light attenuation caused by the evanescent mode, there is a method of thickening the layers between the light-emitting layer 130 and the electrode 101, such as the hole injection layer 111 and the hole transport layer 112. However, when this structure is adopted, problems such as an increase in driving voltage and an increase in manufacturing cost occur.

[0056] Here, in the light emitting element 150 , light generated by the light emitting layer 130 is extracted to the outside, and when the light generated by the light emitting layer 130 passes through the substrate 200 after passing through a layer having a low refractive index, light extraction efficiency is improved.

[0057] The light generated by the light emitting layer 130 passes through the hole injection layer 111, the hole transport layer 112, the electrode 101, and the substrate 200 until it is extracted to the outside. Therefore, the hole injection layer 111 or the hole transport layer 112 preferably has a low refractive index. In particular, the hole injection layer 111 in contact with the electrode 101 preferably has a low refractive index.

[0058] However, in many cases, in order to obtain hole injection characteristics, a substance with electron acceptability is mixed with an organic compound with electron donating property in the hole injection layer 111. Because the substance with electron acceptability is mostly a material with a high refractive index, the refractive index of the hole injection layer 111 becomes high. In other words, it is difficult to obtain a layer with hole injection and a low refractive index. In addition, when the substance with electron acceptability or electron donating property is an organic compound, it is known that when a saturated cyclic compound such as a cyclohexane skeleton is present in the structure of the organic compound, the refractive index decreases, but there is a problem in terms of heat resistance.

[0059] Here, the inventors found that by using an organic compound with a low refractive index in the hole injection layer 111, a layer with a hole injection property and a low refractive index can be manufactured even if a substance with a high refractive index and electron accepting property is used. In addition, the inventors found that by mixing at least one of a tetraarylmethane skeleton and a tetraarylsilane skeleton and an organic compound with an electron donating group into the hole injection layer 111, a layer with a carrier transport property and a low refractive index can be manufactured even if a substance with a high refractive index and electron accepting property is used. Furthermore, the inventors found that the organic compound has high heat resistance. The glass transition point (Tg) of the organic compound is preferably above 100°C.

[0060] The refractive index of the low-refractive-index organic compound is preferably 1 to 1.75, more preferably 1 to 1.73, and further preferably 1.70 or less. With this structure, a light-emitting element with high light extraction efficiency can be obtained.

[0061] The refractive index of the organic compound having an electron donating group and any one of the tetraarylmethane skeleton and the tetraarylsilane skeleton is preferably 1 to 1.75, more preferably 1 to 1.73, and further preferably 1.70 or less. With this structure, a light-emitting element with high light extraction efficiency can be obtained.

[0062] As described above, when a layer with a low refractive index is present between the light-emitting layer 130 and the substrate 200, the light extraction efficiency is improved, but when a layer with a low refractive index is formed in addition to the hole injection layer 111 and the hole transport layer 112, the number of layers manufactured increases and the manufacturing process of the light-emitting element becomes complicated. However, in one embodiment of the present invention, a layer with a low refractive index and a hole injection property can be manufactured, thereby improving the light extraction efficiency of the light-emitting element by using the existing manufacturing process, that is, while maintaining the number of layers manufactured.

[0063] Similarly, in one embodiment of the present invention, a layer having a low refractive index and a hole injection property can be manufactured using any one of a tetraarylmethane skeleton and a tetraarylsilane skeleton and an organic compound having an electron-donating group. Thus, by using the existing manufacturing process, the light extraction efficiency of the light-emitting element can be improved without increasing the number of layers manufactured.

[0064] 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 techniques for improving light extraction, such as forming unevenness on a substrate.

[0065] In addition, in one embodiment of the present invention, an organic compound having an electron donating property is preferably used as an organic compound having a low refractive index. By having this structure, the hole injection property can be improved while reducing the refractive index of the hole injection layer 111, thereby providing a light-emitting element having a high light extraction efficiency and a low driving voltage. The organic compound more preferably has a tetraarylmethane skeleton or a tetraarylsilane skeleton.

[0066] In addition, the refractive index of the hole injection layer 111 is preferably lower than the refractive index of the light emitting layer 130. By having this structure, the attenuation of the light emitted from the light emitting layer 130 due to the evanescent wave can be reduced. In addition, it is more preferred that the refractive index of the hole injection layer 111 is lower than the refractive index of the hole transport layer 112, and the refractive index of the hole transport layer 112 is lower than the refractive index of the light emitting layer 130. By having this structure, the refractive index step between the light emitting layer 130 and the hole injection layer 111 can be reduced, and the light extraction efficiency can be further improved.

[0067] In addition, in order to suppress the waveguide mode of the EL layer, the fewer layers the light generated by the light-emitting layer 130 passes through, the better. Therefore, in terms of light extraction efficiency, the light-emitting layer 130 preferably has a structure in contact with the electrode 101, but when having this structure, the light-emitting layer 130 is sometimes affected by the carrier balance or plasma effect and its luminous efficiency decreases. Therefore, the hole injection layer 111 and the hole transport layer 112 can be said to be layers required for the EL layer to function efficiently. Therefore, it is preferred that the hole injection layer 111 is in contact with the hole transport layer 112, and it is more preferred that the hole transport layer 112 is in contact with the light-emitting layer 130.

[0068] In addition, the refractive index of the hole injection layer 111 is preferably lower than the refractive index of the electrode 101. With this structure, the relationship between the refractive index n HIL of the hole injection layer 111 and the refractive index n cat. of the electrode 101 satisfies n cat. / n HIL>1, thereby suppressing total reflection when light passes from the hole injection layer 111 to the electrode 101. That is, the waveguide mode can be suppressed. In addition, light attenuation caused by the evanescent mode caused by reflection can be suppressed.

[0069] The refractive index of the hole injection layer 111 is preferably 1 to 1.80, more preferably 1 to 1.78, and even more preferably 1 to 1.75. With this structure, high light extraction efficiency can be obtained.

[0070] Furthermore, it is preferable that an organic compound having an electron donating property and a substance having an electron accepting property are mixed in the hole injection layer 111. With such a structure, good hole injection characteristics can be obtained.

[0071] Here, regarding the mixing ratio of the organic compound and the substance having electron accepting property, the volume ratio of the substance having electron accepting property relative to the organic compound is preferably 0.01 or more and 0.3 or less. The inventors of the present invention have found that in this structure, by using an organic compound having a low refractive index as the organic compound, a hole injection layer 111 having a low refractive index can be manufactured even if a substance having a high refractive index is used as the substance having electron accepting property.

[0072] The light incident on the electronic device may also be attenuated by the evanescent wave. For example, when the electronic device of one embodiment of the present invention is used in a solar cell, the light attenuation caused by the evanescent wave can be suppressed, so the light trapping effect of the solar cell can be improved. Therefore, the electronic device of one embodiment of the present invention can be applied to a solar cell. In this case, Figure 1 The functional layer 40 in the electronic device 50 shown is alternatively referred to as an active layer, a light absorbing layer or a photovoltaic layer.

[0073] <Organic Compound for Hole Injection Layer 111> Here, organic compounds that can be used for the hole injection layer 111 are described.

[0074] It is preferable to use an organic compound having a small refractive index for the hole injection layer 111. Here, the refractive index of a polymer is represented by the following Lorentz-Lorenz equation (Equation (1)).

[0075] [Formula 1]

[0076] Formula (2) is obtained by transforming formula (1).

[0077] [Formula 2]

[0078] In equations (1) and (2), n represents the refractive index, α represents the polarizability, N represents the number of molecules per unit volume, ρ represents the density, and N A represents Avogadro's number, M represents molecular weight, V0 represents molar volume, and [R] represents atomic refraction.

[0079] To make the refractive index n smaller than the formula (2), φ can be reduced, and to make φ smaller than the formula (1), the atomic refractive index [R] can be reduced. In other words, to reduce the refractive index n, an organic compound with a smaller atomic refractive index [R] can be selected.

[0080] Since the above formula is a formula for a polymer, the calculated value may be slightly different when the above formula is applied to a low molecular compound, but the tendency can be considered to be roughly the same, so it is preferred to select an organic compound with a small atomic refractive index [R] as the organic compound used for the hole injection layer 111. In addition, the hole injection layer 111 preferably has a hole injection property. Therefore, the organic compound used for the hole injection layer 111 is more preferably π-conjugated and electron-donating in the molecule, such as an aromatic compound. By selecting such an organic compound, a hole injection layer 111 with a low refractive index and excellent hole injection properties can be manufactured.

[0081] When the substituent contains fluorine such as a fluoro group or a trifluoromethyl group, a cyclohexyl group or an aromatic ring, the bond has a sp 3 When the conjugation between aromatic rings represented by hybrid orbitals is cut, the atomic refraction [R] tends to become smaller. In addition, in organic compounds containing non-mutual hydrocarbons, the conjugated system does not expand in the entire molecule, so there is a tendency for the atomic refraction [R] to be small. Therefore, as an organic compound used for the hole injection layer 111, it is preferred to use an organic compound having the above-mentioned substituent or bond.

[0082] As the organic compound used for the hole injection layer 111, an organic compound having an aromatic amine skeleton, a pyrrole skeleton, a thiophene skeleton, or an organic compound having an aromatic ring with a bulky substituent such as a methyl group, a tert-butyl group, an isopropyl group, etc. can be used. Such an organic compound has a π-conjugated system in the molecule and tends to have a lower refractive index.

[0083] As an example of the structure in which the conjugation between aromatic rings is cut in the above-mentioned bonding through aromatic rings, a tetraarylmethane skeleton represented by the following general formula (100), a tetraarylsilane skeleton represented by the general formula (101), or a cyclohexyl skeleton can be cited. The tetraarylmethane skeleton and the tetraarylsilane skeleton have a low refractive index and high heat resistance compared to the cyclohexyl skeleton, and therefore can be applied to the hole injection layer 111. In addition, a thin film can be easily formed by vacuum deposition, so it can be applied to electronic devices such as organic EL.

[0084] [Chemical formula 1]

[0085] The organic compound used for the hole injection layer 111 preferably has an electron donating property. Examples of the electron donating skeleton include aromatic amine skeletons and π-electron-rich heteroaromatic ring skeletons represented by the following general formulae (200) to (220). X in the general formulae (210) to (213) represents oxygen or sulfur.

[0086] [Chemical formula 2]

[0087] The above aromatic amine skeleton (specifically, triarylamine skeleton), π-electron-rich heteroaromatic ring skeleton (specifically, a ring having a furan skeleton, a thiophene skeleton, a pyrrole skeleton, an azapine skeleton or an acridine skeleton) may have a substituent. As the substituent, 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 12 carbon atoms can be selected. As the alkyl group having 1 to 6 carbon atoms, specifically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl can be mentioned. In addition, as the cycloalkyl group having 3 to 6 carbon atoms, specifically, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. can be mentioned. In addition, as the aryl group having 6 to 12 carbon atoms, specifically, phenyl, naphthyl, biphenyl, etc. can be mentioned. In addition, the above substituents can be bonded to each other to form a ring. As an example of this, for example, when the carbon at position 9 of the fluorene skeleton has two phenyl groups as substituents, the phenyl groups are bonded to each other to form a spirofluorene skeleton. In addition, when there is no substitution, it is advantageous in terms of easy synthesis and raw material price.

[0088] As described above, the skeleton with electron donating property is preferably an odd-membered ring skeleton such as an aromatic amine skeleton, a pyrrole skeleton, an azapine skeleton, or an acridine skeleton. These skeletons have good electron donating property and the atomic refraction [R] is also low, so by having these skeletons in the molecule, an organic compound having excellent electron donating property and low refractive index can be obtained.

[0089] In addition, Ar 1To Ar 8 Each independently represents an aryl group having 6 to 13 carbon atoms or an aromatic amine skeleton or a π-electron-rich heteroaromatic skeleton represented by the general formula (200) to (220). The aryl group may have a substituent, and the substituents may be bonded to each other to form a ring. As such an example, for example, the following case can be cited: when the carbon at the 9th position of the fluorenyl group has two phenyl groups as substituents, the phenyl groups are bonded to each other to form a spirofluorene skeleton. As aryl groups having 6 to 13 carbon atoms, phenyl, naphthyl and fluorenyl can be cited. In addition, when the aryl group has a substituent, as the 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 can be selected. As alkyl groups having 1 to 6 carbon atoms, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl can be cited. In addition, specific examples of the cycloalkyl group having 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. In addition, examples of the aryl group having 6 to 12 carbon atoms include phenyl and naphthyl.

[0090] In addition, by Ar 1 To Ar 8 As the aryl group represented by: , for example, a group represented by the following structural formula can be used. In addition, the group that can be used as the aryl group is not limited to this.

[0091] [Chemical formula 3]

[0092] In addition, in Ar 1 To Ar 8 When it is an aryl group, the aryl group is preferably a substituent with a smaller expansion of the π conjugated system, such as a substituted or unsubstituted aryl group with 6 to 13 carbon atoms, and is more preferably a substituted or unsubstituted phenyl group. Substituents with a smaller π conjugated system tend to have a smaller atomic refraction [R]. On the other hand, since organic compounds with a smaller π conjugated system, such as olefins, have low carrier transport properties, they are not suitable for electronic devices. Therefore, as an organic compound for the hole injection layer 111, it is preferred to use an aryl group with 6 to 13 carbon atoms, especially an organic compound with carrier transport properties and a smaller π conjugated system, such as phenyl. In addition, the atomic refraction [R] of the substituent of an odd-membered ring is smaller, so it is preferred.

[0093] In general formulas (200) to (220), R 1 To R 11Respectively independently represent any one of hydrogen, alkyl having 1 to 6 carbon atoms, cycloalkyl having 3 to 6 carbon atoms, and substituted or unsubstituted aryl having 6 to 13 carbon atoms. As alkyl having 1 to 6 carbon atoms, specifically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl etc. can be cited. In addition, as cycloalkyl having 3 to 6 carbon atoms, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl etc. can be cited. In addition, as aryl having 6 to 13 carbon atoms, phenyl, naphthyl, biphenyl, fluorenyl etc. can be cited. And, the above-mentioned aryl and phenyl can have substituents, and the substituents can be bonded to each other to form a ring. In addition, as the substituent, alkyl having 1 to 6 carbon atoms, cycloalkyl having 3 to 6 carbon atoms or aryl having 6 to 12 carbon atoms can be selected. As the alkyl group having 1 to 6 carbon atoms, specifically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl etc. can be mentioned. In addition, as the cycloalkyl group having 3 to 6 carbon atoms, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl etc. can be mentioned. In addition, as the aryl group having 6 to 12 carbon atoms, phenyl, naphthyl, biphenyl etc. can be mentioned.

[0094] In addition, by R 1 To R 11 As the hydrogen, alkyl or aryl group, for example, the groups represented by the following structural formulas (R-1) to (R-27) can be used. In addition, the groups that can be used as the alkyl or aryl group are not limited thereto.

[0095] [Chemical formula 4]

[0096] In general formulae (200) to (220), Ar 9 To Ar 13 Represents an arylene group having 6 to 13 carbon atoms, the arylene group may have a substituent, and the substituents may be bonded to each other to form a ring. As such an example, for example, the following situation can be cited: when the carbon at the 9th position of the fluorene group has two phenyl groups as substituents, the phenyl groups are bonded to each other to form a spirofluorene skeleton. As arylene groups having 6 to 13 carbon atoms, phenylene, naphthalene diyl, biphenylene and fluorene diyl can be cited. In addition, when the arylene group has a substituent, as the 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 can be selected. As an alkyl group having 1 to 6 carbon atoms, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl can be cited. In addition, as a cycloalkyl group having 3 to 6 carbon atoms, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like can be cited. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a naphthyl group, and a biphenyl group.

[0097] In addition, by Ar 9 To Ar 13 The arylene group represented by, for example, the groups represented by the following structural formulas (Ar-12) to (Ar-25) can be used. 9 To Ar 13 The base is not limited to this.

[0098] [Chemical formula 5]

[0099] As described above, the organic compound used for the hole injection layer 111 is preferably an organic compound having a tetraarylmethane skeleton or a tetraarylsilane skeleton and electron donating properties. Examples of such organic compounds include 9-(4-t-butylphenyl)-3,4-ditriphenylmethyl (ditrityl)-9H-carbazole (abbreviated as: CzC), 9-(4-t-butylphenyl)-3,4-ditriphenylsilyl (ditriohenylsilyl)-9H-carbazole (abbreviated as: CzSi), 4,4,8,8,-12,12-hexa-p-toluoyl-4H-8H-12H-12C-aza- Dibenzo[cd,mn]pyrene (abbreviation: FATPA), 4,4'-bis(dibenzo-azepin-1-yl)-biphenyl (abbreviation: BazBP), 4,4'-bis(dihydro-dibenzo-azepin-1-yl)-biphenyl (abbreviation: HBazBP), 4,4'-(diphenylmethylene)bis(N,N-diphenylamine) (abbreviation: TCBPA), 4,4'-(diphenylsilanediyl)bis(N,N-diphenylamine) (abbreviation: TSBPA), etc. Their structural formulas are shown below. Note that organic compounds having the tetraarylmethane skeleton or tetraarylsilane skeleton and electron donating properties are not limited thereto. Their structural formulas are shown below.

[0100] [Chemical formula 6]

[0101] Note that a low-molecular-weight organic compound can be applied to the electronic device of 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, thereby simplifying the manufacturing process.

[0102] 《Improvement of light extraction efficiency by adjusting the optical path length》 Furthermore, by controlling the optical path length of the electronic device of one embodiment of the present invention, the light extraction efficiency can be further improved, and light of a desired wavelength among the light emitted from the light emitting layer 130 can be efficiently extracted.

[0103] 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 between the interface between the electrode 101 and the hole injection layer 111 and the region (light-emitting region 134) in the light-emitting layer 130 where light of a desired wavelength can be obtained to be approximately (2m'-1)λ / 4 (note that m' is a natural number). Note that the light-emitting region described here refers to the region where holes and electrons in the light-emitting layer 130 recombine.

[0104] By performing such optical adjustment, light attenuation caused by the evanescent mode can be reduced, thereby improving the light extraction efficiency from the light emitting layer 130 .

[0105] In addition, it is preferable to adjust the optical distance between the interface between the substrate 200 and the electrode 101 and the region (light emitting region 134) in the light emitting layer 130 where light of a desired wavelength can be obtained to be near mλ / 2 (note that m is a natural number). By performing such optical adjustment, light attenuation caused by the evanescent mode can be reduced, thereby improving the light extraction efficiency from the light emitting layer 130.

[0106] In order to perform the above optical adjustment, it is necessary to adjust the thickness of the hole injection layer 111 or the hole transport layer 112, but when the refractive index of the hole injection layer 111 is high, the optical path length tends to be longer, so it is sometimes difficult to adjust the optical path length or the thickness of the hole injection layer 111 becomes thicker and the driving voltage increases. However, in one embodiment of the present invention, because the hole injection layer 111 has a low refractive index, it is easy to control the optical path length and its thickness can be reduced. Therefore, not only can the light extraction efficiency from the light-emitting layer 130 be improved, but also the manufacturing process of the light-emitting element can be simplified and the light-emitting element can have a low driving voltage.

[0107] The light incident on the electronic device may also be attenuated by the evanescent wave. For example, when the electronic device of one embodiment of the present invention is used in a solar cell, the light attenuation due to the evanescent wave can be suppressed, so the light trapping effect of the organic solar cell can be improved. Therefore, the electronic device of one embodiment of the present invention can be applied to a solar cell. In this case, Figure 1 The functional layer 40 in the illustrated electronic component 50 is referred to as an active layer.

[0108] In the above description of the structure, light is efficiently extracted by adjusting the optical path length of the light emitting element to the wavelength λ of the desired light. Figure 1 The following describes an example of applying the above structure to a solar cell. It is preferred to adjust the thickness between the pair of electrodes in such a way that the optical path length thereof is different from the wavelength λ' of the light incident on the electronic device 50, that is, Figure 1By having this structure, light incident on the electronic device 50 can be efficiently trapped in the electronic device 50. In addition, the electronic device of one embodiment of the present invention can suppress light attenuation caused by evanescent waves, thereby efficiently obtaining a light trapping effect.

[0109] <Materials> Next, 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 in detail.

[0110] Luminous Layer The light-emitting layer 130 includes at least a host material 131, and preferably further includes a guest material 132. In addition, as described below, the host material 131 may include an organic compound 131_1 and an organic compound 131_2. In the light-emitting layer 130, the weight ratio of the host material 131 is the highest, and the guest material 132 is dispersed in the host material 131. In the case where the guest material 132 is a fluorescent compound, the S1 energy level of the host material 131 (organic compound 131_1 and organic compound 131_2) of the light-emitting layer 130 is preferably higher than the S1 energy level of the guest material (guest material 132) of the light-emitting layer 130. In the case where the guest material 132 is a phosphorescent compound, the T1 energy level of the host material 131 (organic compound 131_1 and organic compound 131_2) of the light-emitting layer 130 is preferably higher than the T1 energy level of the guest material (guest material 132) of the light-emitting layer 130.

[0111] The organic compound 131_1 preferably has a heteroaromatic skeleton containing two or more nitrogen atoms and having 1 to 20 carbon atoms. In particular, compounds having a pyrimidine skeleton and a triazine skeleton are preferred. As the organic compound 131_1, a material having a higher electron transport property than a hole transport property (electron transport material) can be used, and preferably a material having a 1×10 -6 cm 2 / Vs or above.

[0112] Specifically, for example, heterocyclic compounds having a diazine skeleton such as 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), and 4,6-bis[3-(9H-carbazole-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) can be used; 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-{3-[3-(benzo[b]naphtho[ Heterocyclic compounds having triazine skeleton, pyrimidine skeleton, triazole skeleton, etc., such as 1,2-d] furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as: mBnfBPTzn), 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (abbreviated as: T2T), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviated as: TmPPPyTz), 9-[4-(3,5-diphenyl-1H-1,2,4-triazole-1-yl)]phenyl-9H-carbazole (abbreviated as: CzTAZ(1H)), etc., are stable and have high reliability, so they are preferred. In addition, heterocyclic compounds having the above skeletons have high electron transport properties, which also help to reduce the driving voltage. The substances described here are mainly those with an electron mobility of 1×10 -6 cm 2 Note that any substance other than the above substances may be used as long as it has a higher electron-transporting property than a hole-transporting property.

[0113] As the organic compound 131_1, a pyridine derivative, a pyrazine derivative, a pyridazine derivative, a bipyridine derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a phenanthroline derivative, a purine compound, or the like can be used. Such an organic compound preferably has a 1×10 -6 cm 2 / Vs or above.

[0114] Specifically, for example, heterocyclic compounds having a pyridine skeleton such as bathophenanthroline (abbreviated as BPhen) and bathocuproin (abbreviated as BCP) can be used; 2-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2mDBTPDBq-II), 2-[3'-(dibenzothiophene-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2CzPDBq -III), 7-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 7mDBTPDBq-II), 6-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 6mDBTPDBq-II), 2-[3-(3,9'-bi-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2mCzCzPDBq), and the like heteroaromatic compounds having a pyrazine skeleton; 3,5-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviated as: 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviated as: TmPyPB), and the like heteroaromatic compounds having a pyridine skeleton. In addition, polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can also be used. Note that as long as the electron transport property is higher than the hole transport property, substances other than the above substances can be used.

[0115] The organic compound 131_2 preferably has a heteroaromatic skeleton containing two or more nitrogen atoms and having 1 to 20 carbon atoms. It is particularly preferred to have a nitrogen-containing five-membered heteroaromatic ring skeleton. For example, an imidazole skeleton, a triazole skeleton, and a tetrazole skeleton can be cited. In addition, as the organic compound 131_2, a material having a hole transport property that is higher than an electron transport property (hole transport material) can be used, preferably a material having a 1×10 -6 cm 2 The hole transport material may be a polymer compound.

[0116] Specifically, for example, 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 9-[4-(4,5-diphenyl-4H-1,2,4-triazol-3-yl)phenyl]-9H-carbazole (abbreviation: CzTAZ1), 2,2',2"-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), etc. can be used.

[0117] As the organic compound 131_2, it is preferred to use other compounds having a nitrogen-containing five-membered heteroaromatic ring skeleton or a tertiary amine skeleton. Specifically, a pyrrole skeleton or an aromatic amine skeleton can be used. For example, indole derivatives, carbazole derivatives, triarylamine derivatives, etc. can be used. In addition, as the organic compound 131_2, a material having a hole transport property higher than an electron transport property (hole transport material) can be used, preferably a material having a 1×10 -6 cm 2 The hole transport material may be a polymer compound.

[0118] As materials with high hole transport properties, specifically, as aromatic amine compounds, there can be mentioned N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc.

[0119] In addition, specific examples of carbazole derivatives include 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviated as PCzTPN2), 3-[N-(9- ... Carbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzPCA1), 3,6-bis[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazole-3-yl)amino]-9-phenylcarbazole (abbreviated as PCzPCN1), 4,4'-bis(9-carbazole)-2,2'-dimethyl-biphenyl (abbreviated as dmCBP), etc.

[0120] In addition, examples of carbazole derivatives include 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tri[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.

[0121] In addition, N,N-diphenyl-9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthracenyl)triphenylamine (abbreviation: DPhPA), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthracenyl)triphenylamine (abbreviation: YGAPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole-3-amine (abbreviation: 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), 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), N,N,N',N',N",N",N"',N"'-octaphenyldibenzo[g,p] (chrysene)-2,7,10,15-tetramine (abbreviation: DBC1), 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl-cyclohexane (abbreviation: TAPC), etc.

[0122] In addition, high molecular weight compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used.

[0123] In addition, as a material with high hole transport properties, for example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as: TPD), 4,4',4"-tri(carbazol-9-yl)triphenylamine (abbreviated as: TCTA), 4,4',4"-tri[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviated as: 1'-TNATA), 4,4',4"-tri(N,N-diphenylamino)triphenylamine (abbreviated as: TDATA), 4,4',4"-tri[N-(3-methylphenyl)-N-phenylamino]triphenylamine amine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-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 amine (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: PCNBB), 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"-tri(9-phenylcarbazole-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-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-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluoren-2-amine (abbreviation: PCASF), 2, Aromatic amine compounds such as 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), N,N'-bis[4-(carbazole-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), etc. In addition, amine compounds and carbazole compounds such as 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated as PCPN), 3-[4-(9-phenanthrenyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated as PCPPn), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as PCCP), 1,3-bis(N-carbazolyl)benzene (abbreviated as mCP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as CzTP), 3,6-bis(9H-carbazole-9-yl)-9-phenyl-9H-carbazole (abbreviated as PhCzGI), and 2,8-bis(9H-carbazole-9-yl)-dibenzothiophene (abbreviated as Cz2DBT) can also be used. Among the above compounds, compounds having a pyrrole skeleton or an aromatic amine skeleton are preferred because they are stable and have good reliability. In addition, the compound having the above skeleton has high hole transport properties, which also contributes to the reduction of driving voltage.

[0124] In the light-emitting layer 130, the guest material 132 is not particularly limited, and anthracene derivatives, tetracene derivatives, Derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, phenothiazine derivatives and the like can be used, for example, the following.

[0125] Specifically, examples of the material include 5,6-bis[4-(10-phenyl-9-anthracenyl)phenyl]-2,2'-bipyridine (abbreviated as PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthracenyl)biphenyl-4-yl]-2,2'-bipyridine (abbreviated as PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluorene-9-yl)phenyl]pyrene-1,6-diamine (abbreviated as 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene-9-yl)phenyl]pyrene- 1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-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-fluoren-9-yl)phenyl]-3,8-dicyclohexylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthracenyl)triphenylamine (abbreviated as: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-diphenyl-2-anthracenyl)triphenylamine (abbreviated as: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole-3-amine (abbreviated as: PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviated as: TBP), 4-(10-phenyl-9-anthracenyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as: P CBAPA), N,N"-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviated as DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthracenyl)phenyl]-9H-carbazole-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthracenyl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), N,N,N',N',N",N",N"',N"'-octaphenyldibenzo[g,p] -2,7,10,15-tetramine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthracenyl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthracenyl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthracenyl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthracenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAB PhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazole-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviated as: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviated as: DPhAPhA), coumarin 6, coumarin 545T, N,N'-diphenylquinacridone (abbreviated as: DPQd), rubrene, 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenylnaphthacene (abbreviated as: TBRb), Nile Red, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenylnaphthacene (abbreviated as: BPT), 2-(2-{2-[4-(dimethylamino)phenyl] ]vinyl}-6-methyl-4H-pyran-4-ylidene)malononitrile (abbreviated as DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviated as DCM2), N,N,N',N'-tetrakis(4-methylphenyl)naphthocene-5,11-diamine (abbreviated as p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviated as p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3 , 6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]vinyl}-4H-pyran-4-ylidene)malononitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviation: DCJTB),5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviated as: BisDCJTM), 5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene, etc.

[0126] As guest material 132 (phosphorescent compound), iridium, rhodium, platinum type organic metal complexes or metal complexes can be cited, among which organic iridium complexes, such as iridium type ortho-metal complexes, are preferred. As ortho-metallated ligands, 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands or isoquinoline ligands can be cited. As metal complexes, platinum complexes with porphyrin ligands can be cited.

[0127] Examples of substances having a light emission peak in the blue or green wavelength region include tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN 2 ]phenyl-κC}iridium(III) (abbreviated as Ir(mpptz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazole)iridium(III) (abbreviated as Ir(Mptz)3), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviated as Ir(iPrptz-3b)3), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviated as Ir(iPr5btz)3), etc. having a 4H-triazole skeleton; tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazole]iridium(III) (abbreviated as Ir( Organometallic iridium complexes with a 1H-triazole skeleton, such as Ir(Mptz1-mp)3), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole)iridium(III) (abbreviated as Ir(Prptz1-Me)3); fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviated as Ir(iPrpmi)3), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviated as Ir(dmpimpt-Me)3), tris{2-[1-(4-cyano)-2,6-diisobutylphenyl)-1H-benzimidazol-2-yl-κN 3]phenyl-κC}iridium(III) (abbreviated as Ir(pbi-diBuCNp)3) and other organometallic iridium complexes with imidazole skeletons; and bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2 '] iridium (III) tetrakis (1-pyrazolyl) borate (abbreviated as FIr6), bis [2-(4',6'-difluorophenyl) pyridinium-N,C 2 '] iridium (III) picolinate (abbreviated as FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinium-N,C 2 '}iridium(III) picolinate (abbreviated as: Ir(CF3ppy)2(pic)), bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2 '] Iridium (III) acetylacetonate (FIr(acac) for short) and other organometallic iridium complexes with phenylpyridine compounds having electron-withdrawing groups as ligands. Among the above metal complexes, organometallic iridium complexes having nitrogen-containing five-membered heterocyclic skeletons such as 4H-triazole skeleton, 1H-triazole skeleton and imidazole skeleton are particularly preferred because of their high triplet excitation energy and excellent reliability and luminous efficiency.

[0128] Examples of substances having a light emission peak in the green or yellow wavelength region include tris(4-methyl-6-phenylpyrimidinyl)iridium(III) (abbreviated as Ir(mppm)3), tris(4-tert-butyl-6-phenylpyrimidinyl)iridium(III) (abbreviated as Ir(tBuppm)3), (acetylacetonate)bis(6-methyl-4-phenylpyrimidinyl)iridium(III) (abbreviated as Ir(mppm)2(acac)), (acetylacetonate)bis(6-tert-butyl-4-phenylpyrimidinyl)iridium(III) (abbreviated as Ir(mppm)2(acac)), and tris(4-tert-butyl-6-phenylpyrimidinyl)iridium(III) (abbreviated as Ir(tBuppm)3). Abbreviations: Ir(tBuppm)2(acac)), (acetylacetonate)bis[4-(2-norbornyl)-6-phenylpyrimidinyl]iridium(III) (abbreviations: Ir(nbppm)2(acac)), (acetylacetonate)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinyl]iridium(III) (abbreviations: Ir(mpmppm)2(acac)), (acetylacetonate)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN 3]phenyl-κC}iridium(III) (abbreviated as Ir(dmppm-dmp)2(acac)), (acetylacetonate)bis(4,6-diphenylpyrimidine)iridium(III) (abbreviated as Ir(dppm)2(acac)), etc., which have a pyrimidine skeleton; (acetylacetonate)bis(3,5-dimethyl-2-phenylpyrazine)iridium(III) (abbreviated as Ir(mppr-Me)2(acac)), (acetylacetonate)bis(5-isopropyl-3-methyl-2-phenylpyrazine)iridium(III) (abbreviated as Ir(mppr-iPr)2(acac)), etc., which have a pyrazine skeleton; tris(2-phenylpyridine-N,C 2 ') iridium (III) (abbreviated as: Ir(ppy)3), bis(2-phenylpyridinium-N,C 2 ') iridium (III) acetylacetonate (abbreviated as Ir(ppy)2(acac)), bis(benzo[h]quinoline)iridium (III) acetylacetonate (abbreviated as Ir(bzq)2(acac)), tris(benzo[h]quinoline)iridium (III) (abbreviated as Ir(bzq)3), tris(2-phenylquinoline-N,C 2′ )iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinoline-N,C 2 ') iridium (III) acetylacetonate (abbreviated as: Ir(pq)2(acac)) and other organic metal iridium complexes with pyridine skeleton; bis(2,4-diphenyl-1,3-oxazole-N,C 2 ') iridium (III) acetylacetonate (abbreviated as: Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl)phenyl]pyridine-N,C 2 '}Iridium(III) acetylacetonate (abbreviated as: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazole-N,C 2 ') Iridium (III) acetylacetonate (abbreviated as Ir(bt)2(acac)) and other organometallic iridium complexes; tris(acetylacetonate)(monophenanthroline)terbium (III) (abbreviated as Tb(acac)3(Phen)) and other rare earth metal complexes. Among the above substances, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they also have significantly excellent reliability and luminous efficiency.

[0129] In addition, as a substance having a light emission peak in the yellow or red wavelength region, for example, (diisobutyrylmethane)bis[4,6-bis(3-methylphenyl)pyrimidinyl]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinyl](dipivaloylmethane)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-di(naphthalene-1-yl)pyrimidinyl](dipivaloylmethane)iridium(III) (abbreviation: Ir(d1npm)2(dpm) ) and other organic metal iridium complexes with a pyrimidine skeleton; (acetylacetonato)bis(2,3,5-triphenylpyrazine)iridium(III) (abbreviated as: Ir(tppr)2(acac)), bis(2,3,5-triphenylpyrazine)(dipivaloylmethanone)iridium(III) (abbreviated as: Ir(tppr)2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxaline]iridium(III) (abbreviated as: Ir(Fdpq)2(acac)) and other organic metal iridium complexes with a pyrazine skeleton; tris(1-phenylisoquinoline-N,C 2’ )iridium(III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinoline-N,C 2’ ) iridium (III) acetylacetonate (abbreviated as: Ir(piq)2(acac)) and other organic metal iridium complexes having a pyridine skeleton; platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum (II) (abbreviated as: PtOEP); and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedione (propanedionato))(monophenanthroline)europium (III) (abbreviated as: Eu(DBM)3(Phen)), tris[1-(2-thenoyl)-3,3,3-trifluoroacetone](monophenanthroline)europium (III) (abbreviated as: Eu(TTA)3(Phen)). Among the above substances, organic metal iridium complexes having a pyrimidine skeleton are particularly preferred because they also have significantly high reliability and luminous efficiency. In addition, organic metal iridium complexes having a pyrazine skeleton can achieve red light with good chromaticity.

[0130] As the luminescent material included in the luminescent layer 130, it is preferred to use a material that can convert triplet excitation energy into luminescence. As the material that can convert triplet excitation energy into luminescence, in addition to phosphorescent compounds, thermally activated delayed fluorescence (TADF) materials can be cited. Therefore, the description of phosphorescent compounds can be regarded as the description of thermally activated delayed fluorescence materials. Note that thermally activated delayed fluorescence materials refer to materials that have a small difference between the triplet excitation energy level and the singlet excitation energy level and have the function of converting energy from the triplet excited state to the singlet excited state through anti-intersystem crossing. Therefore, the triplet excited state can be up-converted (up-converted) to the singlet excited state (anti-intersystem crossing) by a small amount of thermal energy and can efficiently present luminescence (fluorescence) from the singlet excited state. In addition, the conditions for efficiently obtaining thermally activated delayed fluorescence are as follows: the energy difference between the triplet excited state energy level and the singlet excited state emission energy level is greater than 0 eV and is less than 0.2 eV, preferably greater than 0 eV and less than 0.1 eV.

[0131] When the thermally activated delayed fluorescent material is composed of one material, for example, the following materials can be used.

[0132] First, fullerene or its derivatives, acridine derivatives such as proflavine, eosin, etc. Also, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) can be mentioned. As the metal-containing porphyrin, for example, there can be mentioned protoporphyrin-tin fluoride complex (abbreviated as: SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviated as: SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (abbreviated as: SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviated as: SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviated as: SnF2(OEP)), protoporphyrin-tin fluoride complex (abbreviated as: SnF2(Etio I)) and octaethylporphyrin-platinum chloride complex (abbreviated as: PtCl2OEP), etc.

[0133] In addition, as a thermally activated delayed fluorescent material composed of a single material, a heterocyclic compound having a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring can also be used. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazole-11-yl)-1,3,5-triazine (abbreviated as: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as: PCCzPTzn), 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as: PXZ-TRZ) can be cited. , 3-[4-(5-phenyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-oxanthene-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridinium)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracenes]-10'-one (abbreviation: ACRSA), etc. This heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport properties and hole transport properties, so it is preferred. In particular, among the skeletons having π-electron-deficient heteroaromatic rings, diazine skeletons (pyrimidine skeletons, pyrazine skeletons, pyridazine skeletons) or triazine skeletons are stable and have good reliability, so they are preferred. In addition, among the skeletons having π-electron-rich heteroaromatic rings, acridine skeletons, phenoxazine skeletons, thiophene skeletons, furan skeletons and pyrrole skeletons are stable and have good reliability, so it is preferred to have any one or more selected from these skeletons. As the pyrrole skeleton, it is particularly preferred to use an indole skeleton, a carbazole skeleton and a 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole skeleton. In addition, in substances in which a π-electron-rich heteroaromatic ring is directly bonded to a π-electron-deficient heteroaromatic ring, the donor property of the π-electron-rich heteroaromatic ring and the acceptor property of the π-electron-deficient heteroaromatic ring are both strong, and the difference between the energy level of the singlet excited state and the energy level of the triplet excited state is small, so it is particularly preferred.

[0134] In addition, the light-emitting layer 130 may include materials other than the host material 131 and the guest material 132 .

[0135] There is no particular limitation on the material that can be used for the light-emitting layer 130. Examples of the material include anthracene derivatives, phenanthrene derivatives, pyrene derivatives, Derivatives, dibenzo[g,p] Condensed polycyclic aromatic compounds such as derivatives, specifically, 9,10-diphenylanthracene (abbreviation: DPAnth), 6,12-dimethoxy-5,11-diphenyl 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviated as DPPA), 9,10-di(2-naphthyl)anthracene (abbreviated as DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviated as t-BuDNA), 9,9'-bianthracene (abbreviated as BANT), 9,9'-(stilbene-3,3'-diyl)phenanthrene (abbreviated as DPNS), 9,9'-(stilbene-4,4'-diyl)phenanthrene (abbreviated as DPNS2), 1,3,5-tri(1-pyrene)benzene (abbreviated as TPB3), etc. In addition, one or more substances having a singlet excitation energy level or a triplet excitation energy level higher than the excitation energy level of the guest material 132 can be selected from the above substances and known substances and used.

[0136] In addition, for example, a compound having a heteroaromatic skeleton such as an oxadiazole derivative can be used for the light-emitting layer 130. Specifically, for example, heterocyclic compounds such as 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), 9-[4-(5-phenyl-1,3,4-oxadiazole-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), and 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs) can be cited.

[0137] In addition, a metal complex having a heterocyclic ring (e.g., a zinc and aluminum metal complex) can be used for the light-emitting layer 130. For example, a metal complex including a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand can be cited. Specifically, a metal complex having a quinoline skeleton or a benzoquinoline skeleton can be cited, such as tris(8-hydroxyquinoline)aluminum(III) (abbreviated as: Alq), tris(4-methyl-8-hydroxyquinoline)aluminum(III) (abbreviated as: Almq3), bis(10-hydroxybenzo[h]quinoline)beryllium(II) (abbreviated as: BeBq2), bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum(III) (abbreviated as: BAlq), bis(8-hydroxyquinoline)zinc(II) (abbreviated as: Znq), etc. In addition to these, metal complexes having oxazolyl or thiazole ligands such as bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviated as ZnPBO) and bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviated as ZnBTZ) can also be used.

[0138] The light-emitting layer 130 may also be formed of a plurality of layers of more than two layers. For example, in the case where the light-emitting layer 130 is formed by stacking the first light-emitting layer and the second light-emitting layer in sequence from the hole transport layer side, a substance having a hole transport property may be used as the main material of the first light-emitting layer, and a substance having an electron transport property may be used as the main material of the second light-emitting layer. In addition, the light-emitting materials contained in the first light-emitting layer and the second light-emitting layer may also be the same or different materials. In addition, the light-emitting materials contained in the first light-emitting layer and the second light-emitting layer 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 from each other as two light-emitting layers, multiple light emission can be obtained at the same time. In particular, it is preferred to select the light-emitting material for each light-emitting layer so that white light emission can be obtained by combining the light emitted by the two light-emitting layers.

[0139] The light emitting layer 130 may be formed by evaporation (including vacuum evaporation), inkjet, coating, gravure printing, etc. In addition to the above materials, the light emitting layer 130 may also include inorganic compounds such as quantum dots or high molecular compounds (oligomers, dendrimers, polymers, etc.).

[0140] Hole injection layer The hole injection layer 111 has a function of promoting hole injection by reducing the injection barrier of holes from one of a pair of electrodes (electrode 101 or electrode 102), and is formed, for example, using transition metal oxides, phthalocyanine derivatives, aromatic amines, heteropoly acids, etc. with electron acceptability. As transition metal oxides, titanium oxides, vanadium oxides, tantalum oxides, molybdenum oxides, tungsten oxides, rhenium oxides, ruthenium oxides, chromium oxides, zirconium oxides, hafnium oxides, silver oxides, etc. can be cited. The transition metal oxides are superior in electron acceptability and can be easily formed into films using vacuum evaporation or wet methods, so they are preferred. In addition, as phthalocyanine derivatives, phthalocyanine or metal phthalocyanine can be cited. As aromatic amines, benzidine derivatives or phenylenediamine derivatives can be cited. In addition, polymer compounds such as polythiophene or polyaniline can also be used, typically: poly (ethyldioxythiophene) / poly (styrene sulfonic acid) as self-doped polythiophene, etc. Examples of the heteropoly acid include phosphomolybdic acid, phosphotungstic acid, silicomolybdic acid, silicotungstic acid, etc. Heteropoly acids and polymer compounds are preferred because they can easily form a film by a wet method.

[0141] As the hole injection layer 111, it is preferred to use a layer of a composite material comprising the above-mentioned hole transport material with a low refractive index and the above-mentioned material presenting electron acceptance. By having such a structure, a layer with a low refractive index can be formed while having hole injection and transport properties. As an organic material with electron acceptance, TCNQ, F4TCNQ, and F6TCNNQ are preferably used. In addition, a stack of a layer containing a material presenting electron acceptance and a layer containing a hole transport material can also be used. In a steady state or in the presence of an electric field, charge transfer can be performed between these materials. As an organic material presenting electron acceptance, in addition to the above-mentioned TCNQ, F4TCNQ, and F6TCNNQ, organic acceptors such as quinone dimethane derivatives, tetrachlorobenzoquinone derivatives, and hexaazatriphenylene derivatives can also be cited. Specifically, compounds having electron-withdrawing groups (halogen or cyano) such as chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated as: HAT-CN) can be cited. In addition, a substance containing a transition metal such as titanium, vanadium, tantalum, molybdenum, tungsten, rhenium, ruthenium, chromium, zirconium, hafnium, silver, etc. and oxygen can be used. Specifically, titanium oxide, vanadium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, silver oxide, phosphomolybdic acid, molybdenum bronze, and tungsten bronze can be mentioned. Molybdenum oxide is particularly preferably used because it is stable even in the atmosphere, has low hygroscopicity, and is easy to handle.

[0142] As described above, as a hole transport material with a low refractive index for the hole injection layer 111, it is preferred to use an organic compound having a structure in which the conjugation between aromatic rings represented by sp3 bonding is cut off and an organic compound including an aromatic ring with a bulky substituent. As a skeleton having a structure in which the conjugation between aromatic rings is cut off, for example, the above-mentioned tetraarylmethane skeleton and tetraarylsilane skeleton can be cited. However, this compound has a tendency to have low carrier transport and is not suitable for the existing hole injection layer. On the other hand, the effect of improving the hole injection property of the above-mentioned single substance containing transition metals and oxygen is very high, but there is a problem of high refractive index. However, as a material showing electron acceptability, the above-mentioned substance containing transition metals and oxygen is used, and it is combined with a hole transport material with a low refractive index for the hole injection layer 111, thereby simultaneously ensuring the low refractive index and hole injection and transport properties of the hole injection layer 111. That is to say, this structure can eliminate disadvantages and only find advantages. This is because: the electron acceptability of the substance containing transition metal oxide is high, and a small amount of this substance is added to ensure hole injection.

[0143] As the hole transport material, a material having a hole transport property higher than an electron transport property can be used, and preferably a material having a 1×10 -6 cm 2 / Vs or more hole mobility. As described above, the refractive index of the hole transport material is preferably greater than 1 and less than 1.75, more preferably greater than 1 and less than 1.73, and further preferably greater than 1 and less than 1.70. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc., which are listed as hole transport materials that can be used for the light-emitting layer 130, can be used, preferably having a heteroaromatic skeleton with 1 to 20 carbon atoms containing two or more nitrogens. It is particularly preferred to have a nitrogen-containing five-membered heteroaromatic ring skeleton. In addition, the above-mentioned hole transport material can also be a polymer compound.

[0144] In addition, as hole transport materials, aromatic hydrocarbons can also be mentioned, for example, 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: D ...9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 9,10-bis(4-methyl-1-naph MNA), 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'-bianthracene, 10,10'-diphenyl-9,9'-bianthracene, 10,10'-bis(2-phenylphenyl)-9,9'-bianthracene, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthracene, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, and the like. In addition, pentacene, coronene, and the like can also be used. Thus, it is more preferable to use a 1×10 -6 cm 2 / Vs or more and an aromatic hydrocarbon having 14 to 42 carbon atoms.

[0145] The aromatic hydrocarbon may have a vinyl skeleton. Examples of the aromatic hydrocarbon having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

[0146] In addition, 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4',4"-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tri(dibenzothiophen-4-yl)benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[ Thiophene compounds such as 4-(9-phenyl-9H-fluorene-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as: DBTFLP-IV), 4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviated as: mDBTPTp-II), furan compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds, etc. Among them, compounds having a pyrrole skeleton, a furan skeleton, a thiophene skeleton, and an aromatic amine skeleton are stable and have good reliability, so they are preferred. Compounds having the above skeletons have high hole transport properties and also contribute to the reduction of driving voltage.

[0147] Hole transport layer The hole transport layer 112 is a layer containing a hole transport material, and the hole transport material exemplified as the material of the hole injection layer 111 can be used. The hole transport layer 112 has the function of transporting the holes injected into the hole injection layer 111 to the light-emitting layer 130, so it preferably has a HOMO energy level that is the same as or close to the HOMO (Highest Occupied Molecular Orbital, also called the highest occupied molecular orbital) energy level of the hole injection layer 111.

[0148] In addition, it is preferred to use a 1×10 -6 cm 2 / Vs or more. However, as long as the hole transport property is higher than the electron transport property, a substance other than the above substances can be used. In addition, the layer including the substance with high hole transport property is not limited to a single layer, and two or more layers composed of the above substances can be stacked.

[0149] Electron Transport Layer The electron transport layer 118 has a function of transporting electrons injected from the other of the pair of electrodes (electrode 101 or electrode 102) through the electron injection layer 119 to the light-emitting layer 130. As the electron transport material, a material having a higher electron transport property than a hole transport property can be used, and preferably a material having a 1×10 -6 cm 2 / Vs or higher electron mobility. As a compound that easily accepts electrons (a material with electron transport properties), a nitrogen-containing heteroaromatic compound or a π-electron-deficient heteroaromatic or metal complex can be used. Specifically, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, triazole derivatives, benzimidazole derivatives, oxadiazole derivatives, etc., which are electron transport materials that can be used for the light-emitting layer 130, are mentioned, preferably having a heteroaromatic skeleton with 1 to 20 carbon atoms containing two or more nitrogen atoms. Particularly preferred are compounds having a pyrimidine skeleton and a triazine skeleton. In addition, it is preferred to have a 1×10 -6 cm 2 / Vs or higher. In addition, as long as the electron transport property is higher than the hole transport property, a substance other than the above substances can be used as the electron transport layer 118. In addition, the electron transport layer 118 is not limited to a single layer, and two or more layers composed of the above substances can be stacked.

[0150] In addition, metal complexes having heterocyclic rings can also be mentioned, for example, metal complexes including quinoline ligands, benzoquinoline ligands, oxazole ligands or thiazole ligands. Specifically, metal complexes having quinoline skeletons or benzoquinoline skeletons can be mentioned, such as tris(8-hydroxyquinoline)aluminum(III) (abbreviated as: Alq), tris(4-methyl-8-hydroxyquinoline)aluminum(III) (abbreviated as: Almq3), bis(10-hydroxybenzo[h]quinoline)beryllium(II) (abbreviated as: BeBq2), bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum(III) (abbreviated as: BAlq), bis(8-hydroxyquinoline)zinc(II) (abbreviated as: Znq), etc. In addition to these, metal complexes having oxazolyl ligands or thiazole ligands such as bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviated as ZnPBO) and bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviated as ZnBTZ) can also be used.

[0151] In addition, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light emitting layer 130. The layer for controlling the movement of electron carriers is a layer formed by adding a small amount of a substance with high electron capture property to the above-mentioned material with high electron transport property, and the carrier balance can be adjusted by suppressing the movement of electron carriers. This structure has a great effect on suppressing problems (such as a decrease in the life of the element) that occur when the electron transport property of the electron transport material is much higher than the hole transport property of the hole transport material.

[0152] 《Electron injection layer》 The electron injection layer 119 has the function of lowering the injection barrier of electrons from the electrode 102 to promote electron injection. For example, Group 1 metals, Group 2 metals or their oxides, halides, carbonates, etc. can be used. In addition, a composite material of the above-mentioned electron transport material and a material that has electron supply properties to the electron transport material can also be used. As electron supply materials, Group 1 metals, Group 2 metals or their oxides can be cited. Specifically, lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2) and lithium oxide (LiO x ) or other alkali metals, alkaline earth metals, or compounds of these metals. In addition, rare earth metal compounds such as erbium fluoride (ErF3) can be used. In addition, electron salts can also be used for the electron injection layer 119. As the electron salt, for example, a substance that adds electrons to a mixed oxide of calcium and aluminum at a high concentration can be cited. In addition, a substance that can be used for the electron transport layer 118 can also be used for the electron injection layer 119.

[0153] In addition, a composite material formed by mixing an organic compound with an electron donor (donor) can also be used for the electron injection layer 119. This composite material has excellent electron injection and electron transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material with excellent performance in transporting the generated electrons. Specifically, for example, the substances (metal complexes, heteroaromatic compounds, etc.) constituting the electron transport layer 118 as described above can be used. As an electron donor, any substance that exhibits electron donating properties to organic compounds can be used. Specifically, alkali metals, alkaline earth metals and rare earth metals are preferably used, and lithium, sodium, cesium, magnesium, calcium, erbium, ytterbium, etc. can be cited. In addition, alkali metal oxides or alkaline earth metal oxides are preferably used, and lithium oxide, calcium oxide, barium oxide, etc. can be cited. In addition, Lewis bases such as magnesium oxide can also be used. In addition, organic compounds such as tetrathiafulvalene (abbreviated as: TTF) can also be used.

[0154] In addition, the above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer and electron injection layer can be formed by evaporation (including vacuum evaporation), inkjet, coating, gravure printing and other methods. In addition, as the above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer and electron injection layer, in addition to the above-mentioned materials, inorganic compounds such as quantum dots or high molecular compounds (oligomers, dendrimers, polymers, etc.) can also be used.

[0155] "Quantum Dot" Quantum dots are semiconductor nanocrystals with a size of several nanometers to tens of nanometers and include 1×10 3 to 1 10 6The energy transfer of quantum dots depends on their size, so even quantum dots made of the same substance have different emission wavelengths depending on their size. Therefore, by changing the size of the quantum dots used, the emission wavelength can be easily changed.

[0156] In addition, the peak width of the emission spectrum of quantum dots is narrow, so that light with high color purity can be obtained. Furthermore, the theoretical internal quantum efficiency of quantum dots is considered to be almost 100%, that is, it greatly exceeds 25% of organic compounds that exhibit fluorescent light emission and is equal to organic compounds that exhibit phosphorescent light emission. Therefore, by using quantum dots as luminescent materials, a light-emitting element with high luminous efficiency can be obtained. Moreover, quantum dots as inorganic materials are also excellent in substantial stability, so a light-emitting element with a long life can be obtained.

[0157] As materials constituting quantum dots, there can be cited Group 14 elements, Group 15 elements, Group 16 elements, compounds containing multiple Group 14 elements, compounds of Group 4 to Group 14 elements 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, chalcogenides, semiconductor clusters, and the like.

[0158] 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 phosphide, 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 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, zirconium oxide, silicon nitride, germanium nitride, aluminum oxide, barium titanate, selenium zinc cadmium compound, indium arsenic phosphorus compound, cadmium selenium sulfur compound, cadmium selenium tellurium compound, indium gallium arsenic compound, indium gallium selenide compound, indium selenium sulfur compound, copper indium sulfur compound and their combination, but not limited thereto. In addition, so-called alloy-type quantum dots with arbitrary numbers representing the composition can also be used. For example, cadmium-selenium-sulfur alloy quantum dots are one of the effective means for obtaining blue light emission because the emission wavelength can be changed by changing the content ratio of the elements.

[0159] As the structure of quantum dot, there are core type, core shell (Core Shell) type, core multi-shell (Core Multishell) type etc.. Any of the above can be used, but by using other inorganic materials covering the core and having a wider band gap to form a shell, the influence of defects or dangling bonds present on the surface of the nanocrystal can be reduced, thereby significantly improving the quantum efficiency of luminescence. Thus, preferably use a core shell type or core multi-shell type quantum dot. As an example of the material of the shell, zinc sulfide or zinc oxide can be cited.

[0160] In addition, in quantum dots, since the proportion of surface atoms is high, the reactivity is high and aggregation occurs easily. Therefore, the surface of the quantum dots is preferably attached with a protective agent or provided with a protective group. This can prevent aggregation and improve the solubility in solvents. In addition, the electrical stability can be improved by reducing the reactivity. Examples of protective agents (or protective groups) include: polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene ole ... ether) and other polyoxyethylene alkyl ethers; tripropyl phosphine, tributyl phosphine, trihexyl phosphine, trioctyl phosphine and other trialkyl phosphines; polyoxyethylene n-octyl phenyl ether, polyoxyethylene n-nonyl phenyl ether and other polyoxyethylene alkyl phenyl ethers; tri(n-hexyl)amine, tri(n-octyl)amine, tri(n-decyl)amine and other tertiary amines; tripropyl phosphine oxide, tributyl phosphine oxide, trihexyl phosphine oxide, trioctyl phosphine oxide, tridecyl phosphine oxide and other organic phosphorus compounds; polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate; Organic nitrogen compounds such as pyridine, lutiidine, collidine, quinoline and other nitrogen-containing aromatic compounds; aminoalkanes such as hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine and other aminoalkanes; 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, oleic acid; ethanol; sorbitan fatty acid esters; fatty acid-modified polyesters; tertiary amine-modified polyurethanes; polyethyleneimines, etc.

[0161] The smaller the size of the quantum dot, the larger the band gap, so the size is appropriately adjusted to obtain the desired wavelength of light. The smaller the crystal size, the more the luminescence of the quantum dot migrates to the blue side (i.e., the high energy side), so by changing the size of the quantum dot, the luminescence wavelength can be adjusted to the wavelength region of the spectrum of the ultraviolet region, the visible light region, and the infrared region. The size (diameter) of the commonly used quantum dots is 0.5nm to 20nm, preferably 1nm to 10nm. In addition, the smaller the size distribution of the quantum dot, the narrower the emission spectrum, so luminescence with high color purity can be obtained. In addition, there is no particular restriction on the shape of the quantum dot, which can be spherical, rod-shaped, disc-shaped, or other shapes. In addition, the quantum rod as a rod-shaped quantum dot has the function of presenting directional light, so by using the quantum rod as a luminescent material, a light-emitting element with higher external quantum efficiency can be obtained.

[0162] In organic EL elements, the concentration quenching of the luminescent material is usually suppressed by dispersing the luminescent material in the host material, thereby improving the luminous efficiency. The host material needs to have a singlet excitation energy level or a triplet excitation energy level higher than the luminescent material. In particular, when a blue phosphorescent material is used as a luminescent material, a host material with a triplet excitation energy level higher than the blue phosphorescent material and a long service life is required, and the development of such a material is extremely difficult. Here, quantum dots can ensure luminous efficiency even when only quantum dots are used to form a luminescent layer without using a host material, so a luminescent element with a long service life can be obtained. When only quantum dots are used to form a luminescent layer, the quantum dots preferably have a core-shell structure (including a core-multi-shell structure).

[0163] When quantum dots are used as the luminescent material of the luminescent layer, the thickness of the luminescent layer is 3nm to 100nm, preferably 10nm to 100nm, and the ratio of quantum dots contained in the luminescent layer is 1vol.% to 100vol.%. Note that it is preferred that the luminescent layer is formed only by quantum dots. In addition, when forming a luminescent layer in which the quantum dots are used as luminescent materials and dispersed in a host material, the quantum dots can be dispersed in the host material or the host material and the quantum dots can be dissolved or dispersed in a suitable liquid medium, and formed using a wet method (spin coating, casting, dye coating, blade coating, roller coating, inkjet, printing, spraying, curtain coating, Langmuir-Blodgett method, etc.). In addition to the above-mentioned wet method, the luminescent layer using phosphorescent luminescent materials preferably adopts a vacuum evaporation method.

[0164] As the liquid medium used for the wet method, 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, cyclohexylbenzene; aliphatic hydrocarbons such as cyclohexane, decalin, dodecane; organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0165] A pair of electrodes The electrode 101 and the electrode 102 are used as an anode or a cathode 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 a stacked body thereof, or the like.

[0166] One of the electrode 101 and the electrode 102 is preferably formed using a conductive material having a function of reflecting light. As the conductive material, aluminum (Al) or an alloy containing Al can be cited. As the alloy containing Al, an alloy containing Al and L (L represents one or more of titanium (Ti), neodymium (Nd), nickel (Ni) and lanthanum (La)) can be cited, for example, an alloy containing Al and Ti or an alloy containing Al, Ni and La. Aluminum has low resistivity and high light reflectivity. In addition, since aluminum is contained in large quantities in the earth's crust and is not expensive, the use of aluminum can reduce the manufacturing cost of the light-emitting element. In addition, silver (Ag), alloys containing Ag, N (N represents one or more 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) can also be used. As alloys containing silver, for example, the following alloys can be cited: 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, etc. In addition to the above materials, transition metals such as tungsten, chromium (Cr), molybdenum (Mo), copper and titanium can be used.

[0167] In addition, light obtained from the light-emitting layer is extracted through one or both of the electrode 101 and the electrode 102. Therefore, at least one of the electrode 101 and the electrode 102 is preferably formed using a conductive material having a function of transmitting light. Examples of the conductive material include a material having a visible light transmittance of 40% or more and 100% or less, preferably 60% or more and 100% or less, and a resistivity of 1×10 -2 Conductive materials with a resistance of Ω·cm or less.

[0168] In addition, the electrodes 101 and 102 may be formed using a conductive material having a function of transmitting light and a function of reflecting light. Examples of the conductive material include a material having a visible light reflectance of 20% or more and 80% or less, preferably 40% or more and 70% or less, and a resistivity of 1×10 -2Conductive materials with a resistance of less than Ω·cm. For example, one or more of conductive metals, alloys and conductive compounds can be used. Specifically, metal oxides such as indium tin oxide (hereinafter referred to as ITO), indium tin oxide containing silicon or silicon oxide (abbreviated as: ITSO), indium zinc oxide (Indium Zinc Oxide), indium oxide-tin oxide containing titanium, indium-titanium oxide, indium oxide containing tungsten oxide and zinc oxide. In addition, a metal film having a thickness that allows light to pass (preferably a thickness of more than 1 nm and less than 30 nm) can be used. As the metal, for example, alloys of Ag, Ag and Al, Ag and Mg, Ag and Au, and Ag and Yb can be used.

[0169] Note that in this specification, as a material having a light-transmitting function, a material having a function of transmitting visible light and having conductivity may be used, such as the oxide conductor represented by ITO (Indium Tin Oxide), an oxide semiconductor, or an organic conductor containing organic matter. As an organic conductor containing organic matter, for example, a composite material containing a mixed organic compound and an electron donor (donor), a composite material containing a mixed organic compound and an electron acceptor (acceptor), etc. can be cited. Inorganic carbon materials such as graphene can also be used. In addition, the resistivity of the material is preferably 1×10 5 Ω·cm or less, more preferably 1×10 4 Ω·cm or less.

[0170] In addition, one or both of the electrode 101 and the electrode 102 may be formed by stacking a plurality of the above-mentioned materials.

[0171] In order to improve the light extraction efficiency, a material having a refractive index higher than that of the electrode can be formed in contact with the electrode having the function of transmitting light. As such a material, as long as it has the function of transmitting visible light, it can be a conductive material or a non-conductive material. For example, in addition to the above-mentioned oxide conductors, oxide semiconductors and organic substances can also be cited. As organic substances, for example, materials illustrated as light-emitting layers, hole injection layers, hole transport layers, electron transport layers, or electron injection layers can be cited. In addition, inorganic carbon materials or metal films having a thickness that allows light to be transmitted can also be used, and multiple layers having a thickness of several nm to tens of nm can be stacked.

[0172] When the electrode 101 or the electrode 102 is used as a cathode, it is preferable to use 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 (e.g., alkali metals such as lithium, sodium, and cesium, alkaline earth metals such as calcium or strontium, magnesium, etc.), alloys containing the above elements (e.g., Ag and Mg or Al and Li), rare earth metals such as europium (Eu) or Yb, alloys containing the above rare earth metals, alloys containing aluminum and silver, etc. can be used.

[0173] When the electrode 101 or the electrode 102 is used as an anode, it is preferable to use a material having a large work function (4.0 eV or more).

[0174] Electrodes 101 and 102 may also be made of a stack of conductive materials having a function of reflecting light and conductive materials having a function of transmitting light. In this case, electrodes 101 and 102 have the function of adjusting the optical distance so that the light of the desired wavelength from each light-emitting layer resonates and enhances the light of the desired wavelength, so it is preferred.

[0175] As a film forming method of the electrode 101 and the electrode 102 , sputtering, vapor deposition, printing, coating, MBE (Molecular Beam Epitaxy) method, CVD method, pulse laser deposition method, ALD (Atomic Layer Deposition) method, etc. can be appropriately used.

[0176] Substrate The light-emitting element of one embodiment of the present invention can be manufactured over a substrate made of glass, plastic, etc. The order of stacking layers on the substrate may be stacked from the electrode 101 side or from the electrode 102 side.

[0177] In addition, as a substrate capable of forming a light-emitting element of one embodiment of the present invention, for example, glass, quartz or plastic can be used. Alternatively, a flexible substrate can also be used. A flexible substrate is a substrate that can be bent, such as a plastic substrate made of polycarbonate or polyarylate. In addition, a film, an inorganic vapor-deposited film, etc. can be used. Note that other materials can be used as long as they serve as a support in the manufacturing process of the light-emitting element and the optical element. Alternatively, any material can be used as long as it has the function of protecting the light-emitting element and the optical element.

[0178] For example, in the present invention, various substrates can be used to form light-emitting elements. There is no particular restriction on the type of substrate. As examples of the substrate, for example, semiconductor substrates (for example, single crystal substrates or silicon substrates), SOI substrates, glass substrates, quartz substrates, plastic substrates, metal substrates, stainless steel substrates, substrates with stainless steel foil, tungsten substrates, substrates with tungsten foil, flexible substrates, laminated films, paper containing fibrous materials or substrate films, etc. can be used. As examples of glass substrates, there are barium borosilicate glass, aluminum borosilicate glass, soda-lime glass, etc. As flexible substrates, laminated films, substrate films, etc., the following examples can be cited. For example, plastics represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), and polytetrafluoroethylene (PTFE) can be cited. Alternatively, as an example, resins such as acrylic resins can be cited. Alternatively, as an example, polypropylene, polyester, polyvinyl fluoride or polyvinyl chloride can be cited. Alternatively, polyamide, polyimide, aramid, epoxy resin, inorganic vapor-deposited film, paper, etc. can be cited as examples.

[0179] In addition, a flexible substrate may be used as a substrate, and a light-emitting element may be directly formed on the flexible substrate. Alternatively, a peeling layer may be provided between the substrate and the light-emitting element. The peeling layer may be used when a part or all of the light-emitting element is manufactured on the peeling layer, and then it is separated from the substrate and transferred to another substrate. In this case, the light-emitting element may also be transferred to a substrate with low heat resistance or a flexible substrate. In addition, as the above-mentioned peeling layer, for example, a laminated structure of an inorganic film of a tungsten film and a silicon oxide film or a structure in which a resin film such as polyimide is formed on a substrate may be used.

[0180] That is, a light-emitting element can also be formed using one substrate, and then the light-emitting element can be transferred to another substrate. As examples of substrates to which the light-emitting element is transferred, in addition to the above-mentioned substrates, there can be cited cellophane substrates, stone substrates, wood substrates, cloth substrates (including natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester) or regenerated fibers (acetate, cuprammonium fiber, rayon, regenerated polyester), etc.), leather substrates, rubber substrates, etc. By using these substrates, it is possible to manufacture light-emitting elements that are not easily damaged, light-emitting elements with high heat resistance, light-emitting elements that are lightweight, or light-emitting elements that are thin.

[0181] Alternatively, a field effect transistor (FET) may be formed over the substrate, and the light emitting element 150 may be formed on an electrode electrically connected to the FET. Thus, an active matrix display device in which driving of the light emitting element 150 is controlled by the FET can be manufactured.

[0182] Hereinafter, components of a solar cell which is an example of an electronic device according to one embodiment of the present invention will be described.

[0183] In solar cells, materials that can be used for the above-mentioned light-emitting elements can be used. In the carrier transport layer of the solar cell, the above-mentioned hole transport materials and electron transport materials can be used, and in the photovoltaic layer, the above-mentioned hole transport materials, electron transport materials, light-emitting materials, and perovskite crystals represented by silicon or CH3NH3PbI3 can be used. In addition, for the substrate or electrode, materials that can be used for the above-mentioned light-emitting elements can be used.

[0184] The structure described in this embodiment mode can be used in combination with other embodiment modes as appropriate.

[0185] (Implementation Method 2) In this embodiment, a light-emitting element having a structure different from that described in Embodiment 1 and a light-emitting mechanism of the light-emitting element are described with reference to FIGS. 3 and 4. Figure 2A The same hatching shows Figure 2A The same function as the part, and sometimes the reference numeral is omitted. Figure 2A Components with the same functions are denoted by the same reference numerals, and detailed description thereof may be omitted.

[0186] <Structural Example 1 of Light Emitting Element> Figure 3A is a schematic cross-sectional view of the light emitting element 250 .

[0187] Figure 3A The light emitting element 250 shown has a plurality of light emitting units ( Figure 3A 106 and 108 in the light-emitting element 250). Note that in the light-emitting element 250, although the case where the electrode 101 is an anode and the electrode 102 is a cathode is described, the opposite structure may be adopted.

[0188] In addition, Figure 3A In the light emitting element 250 shown, the light emitting unit 106 and the light emitting unit 108 are stacked, and the charge generation 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 structure or different structures.

[0189] In addition, the light-emitting element 250 includes a light-emitting layer 120 and a light-emitting layer 170. In addition, the light-emitting unit 106 includes 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. In addition, the light-emitting unit 108 includes 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.

[0190] The charge generation layer 115 may have a structure in which an acceptor substance serving as an electron acceptor is added to a hole transport material, or a structure in which a donor substance serving as an electron donor is added to an electron transport material. Alternatively, these two structures may be stacked.

[0191] When the charge generation layer 115 includes a composite material composed of an organic compound and an acceptor substance, the composite material that can be used for the hole injection layer 111 described in Embodiment 1 can be used as the composite material. As the organic compound, various compounds such as aromatic amine compounds, carbazole compounds, aromatic hydrocarbons, and high molecular weight compounds (oligomers, dendrimers, polymers, etc.) can be used. In addition, as the organic compound, it is preferred to use an organic compound having a hole mobility of 1×10 -6 cm 2 / Vs or above. However, as long as the hole transport property is higher than the electron transport property, substances other than these can be used. Because the composite material composed of organic compounds and acceptor substances has good carrier injection and carrier transport properties, low voltage drive and low current drive can be achieved. Note that when the surface on the anode side of the light-emitting unit contacts the charge generation layer 115, the charge generation layer 115 can also have the function of the hole injection layer or hole transport layer of the light-emitting unit, so the light-emitting unit can also have a structure in which the hole injection layer or the hole transport layer is not provided. Note that when the surface on the cathode side of the light-emitting unit contacts the charge generation layer 115, the charge generation layer 115 can also have the function of the electron injection layer or the electron transport layer of the light-emitting unit, so the light-emitting unit can also have a structure in which the electron injection layer or the electron transport layer is not provided.

[0192] Note that the charge generation layer 115 may also be a laminated structure in which a layer of a composite material including an organic compound and an acceptor substance is combined with a layer composed of other materials. For example, a structure in which a layer of a composite material including an organic compound and an acceptor substance is combined with a layer including a compound selected from electron-donating substances and a compound with high electron transport properties may be combined. Alternatively, a structure in which a layer of a composite material including an organic compound and an acceptor substance is combined with a layer including a transparent conductive film may be combined.

[0193] The charge generation layer 115 sandwiched between the light-emitting unit 106 and the light-emitting unit 108 may have a structure that injects electrons into one light-emitting unit and injects holes into the other light-emitting unit when a voltage is applied between the electrode 101 and the electrode 102. Figure 3A In the embodiment, when a voltage is applied so that the potential of the electrode 101 is 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 .

[0194] From the viewpoint of light extraction efficiency, the charge generation layer 115 preferably has visible light transmittance (specifically, the charge generation layer 115 has a visible light transmittance of 40% or more). The charge generation layer 115 functions even if its conductivity is lower than that of the pair of electrodes (electrode 101 and electrode 102).

[0195] By forming the charge generation layer 115 using the above-mentioned material, an increase in driving voltage when a light-emitting layer is stacked can be suppressed.

[0196] Although in Figure 3A , a light-emitting element having two light-emitting units is described, but the same structure can be applied to a light-emitting element having three or more light-emitting units stacked. As shown in light-emitting element 250, by arranging a plurality of light-emitting units between a pair of electrodes in a manner separated by a charge generation layer, a light-emitting element that can emit light at high brightness while maintaining a low current density and has a longer service life can be realized. In addition, a light-emitting element with low power consumption can also be realized.

[0197] In each of the above structures, the luminescent colors presented by the guest materials used for the light-emitting unit 106 and the light-emitting unit 108 may be the same or different. When the light-emitting unit 106 and the light-emitting unit 108 include guest materials having the function of presenting the same color, the light-emitting element 250 becomes a light-emitting element that presents high luminescence brightness at a small current value, so it is preferred. In addition, when the light-emitting unit 106 and the light-emitting unit 108 include guest materials having the function of presenting light of different colors from each other, the light-emitting element 250 becomes a light-emitting element that presents multi-color light emission, so it is preferred. At this time, since a plurality of light-emitting materials with different luminescent wavelengths are used as one or both of the light-emitting layer 120 and the light-emitting layer 170, light with different luminescent peaks is synthesized, the emission spectrum presented by the light-emitting element 250 has at least two maximum values.

[0198] The above structure is suitable for obtaining white light emission. White light emission can be obtained by making the light of the light emitting layer 120 and the light emitting layer 170 complementary colors. It is particularly preferred to select the guest material in a manner that realizes white light emission with high color rendering index or light emission having at least red, green, and blue.

[0199] In addition, in a light-emitting element having three or more stacked light-emitting units, the light-emitting colors of the guest materials used for each light-emitting unit may be the same or different. In the case where the light-emitting element includes a plurality of light-emitting units emitting light of the same color, these plurality of light-emitting units can obtain a light-emitting color with high light-emitting brightness at a current value lower than that of other colors. This structure is suitable for adjusting the light-emitting color. It is particularly preferred for use in the case of using guest materials with different luminous efficiencies and exhibiting different light-emitting colors. For example, in the case of setting three light-emitting units, by setting two light-emitting units containing a fluorescent material exhibiting the same light-emitting color and one light-emitting unit containing a phosphorescent material exhibiting a light-emitting color different from that of the fluorescent material, the light-emitting intensity of the fluorescent light and the phosphorescent light can be adjusted. In other words, the intensity of the light-emitting color can be adjusted according to the number of light-emitting units.

[0200] In the case of using the above-mentioned light-emitting element including two fluorescent light-emitting units and one phosphorescent light-emitting unit, in order to efficiently obtain white light emission, it is preferably adopted the following structure: a structure in which the light-emitting unit includes two light-emitting units including blue fluorescent material and one light-emitting unit including yellow phosphorescent material; a structure in which the light-emitting unit includes two light-emitting units including blue fluorescent material and one light-emitting unit including red phosphorescent material and green phosphorescent material; a structure in which the light-emitting unit includes two light-emitting units including blue fluorescent material and one light-emitting unit including red phosphorescent material, yellow phosphorescent material and green phosphorescent material.

[0201] In addition, at least one of the light-emitting layer 120 and the light-emitting layer 170 may be further divided into layers and each of the divided layers may contain a different light-emitting material. That is, at least one of the light-emitting layer 120 and the light-emitting layer 170 may also be formed by a plurality of layers of two or more. For example, in the case where the light-emitting layer is formed by stacking the first light-emitting layer and the second light-emitting layer in sequence from the hole transport layer side, a material having a hole transport property may be used as the main material of the first light-emitting layer, and a material having an electron transport property may be used as the main material of the second light-emitting layer. In this case, the light-emitting materials contained in the first light-emitting layer and the second light-emitting layer may also be the same or different materials. In addition, the light-emitting materials contained in the first light-emitting layer and the second light-emitting layer 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 adopting a structure of a plurality of light-emitting materials having the function of emitting light of different colors from each other, white light with high color rendering properties consisting of three primary colors or four or more light-emitting colors may also be obtained.

[0202] In addition, by applying the structure described in Embodiment 1 to at least one of a plurality of units, a light-emitting element having high light extraction efficiency and reduced driving voltage can be provided.

[0203] In addition, if Figure 3B As shown, the light-emitting layer 120 included in the light-emitting unit 108 includes a guest material 121 and a host material 122. In the following, the fluorescent material is used as the guest material 121 for description.

[0204] 《Luminescence Mechanism of Luminescent Layer 120》 Next, the light emitting mechanism of the light emitting layer 120 is described.

[0205] Electrons and holes injected from a pair of electrodes (electrode 101 and electrode 102) or the charge generation layer 115 are recombined in the light emitting layer 120, thereby generating excitons. Since the host material 122 is present in a larger amount than the guest material 121, the host material 122 is almost in an excited state due to the generation of excitons. Note that an exciton refers to a pair of carriers (electrons and holes).

[0206] When the formed excited state of the host material 122 is a singlet excited state, the singlet excitation energy is transferred from the S1 energy level of the host material 122 to the S1 energy level of the guest material 121 , thereby forming the singlet excited state of the guest material 121 .

[0207] 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 will emit light rapidly. At this time, in order to obtain high luminous efficiency, the guest material 121 preferably has a high fluorescence quantum yield. In addition, this is also the case when the excited state generated by carrier recombination in the guest material 121 is a singlet excited state.

[0208] Next, the formation of a triplet excited state of the host material 122 due to recombination of carriers will be described. Figure 3C The energy level relationship between the host material 122 and the guest material 121 at this time is shown. Figure 3C The descriptions and symbols in 12 are as follows. Note that since the T1 level of the host material 122 is preferably lower than the T1 level of the guest material 121, Figure 3C The situation at this time is shown in , but the T1 energy level of the host material 122 can also be higher than the T1 energy level of the guest material 121.

[0209] Guest (121): Guest material 121 (fluorescent material) Host(122): Main material 122 S FG : S1 level of guest material 121 (fluorescent material) T FG : T1 level of guest material 121 (fluorescent material) S FH : S1 level of host material 122 T FH: T1 level of host material 122

[0210] like Figure 3C As shown, due to triplet-triplet annihilation (TTA), triplet excitons generated by the recombination of carriers interact with each other, supplying excitation energy and exchanging spin angular momentum, thereby converting them to the S1 level (S2) of the host material 122. FH ) of the energy of the singlet exciton (refer to Figure 3C The singlet excitation energy of the host material 122 is increased from S FH The energy level (S1) of the guest material 121 is lower than that of the guest material 121. FG ) (refer to Figure 3C Path E1), forming a singlet excited state of the guest material 121, thereby the guest material 121 emits light.

[0211] In addition, when the density of triplet excitons in the light-emitting layer 120 is sufficiently high (e.g., 1×10 12 cm -3 When the deactivation of a single triplet exciton is neglected, only the reaction of two close triplet excitons is considered.

[0212] In addition, when carriers recombine in the guest material 121 to form a triplet excited state, the triplet excited state of the guest material 121 is thermally deactivated and thus difficult to use for light emission. FH ) is lower than the T1 energy level (T FG ), the triplet excitation energy of the guest material 121 can be increased from the T1 energy level (T FG ) is transferred to the T1 energy level (T FH ) (refer to Figure 3C Path E2) is then used for TTA.

[0213] That is, the host material 122 preferably has a function of converting triplet excitation energy into singlet excitation energy using TTA. Thus, by using TTA in the host material 122 to convert a portion of the triplet excitation energy generated in the light-emitting layer 120 into singlet excitation energy, and transferring the singlet excitation energy to the guest material 121, it is possible to extract fluorescent light. For this reason, the S1 energy level (S FH ) is preferably higher than the S1 energy level (S FG In addition, the T1 energy level (T FH ) is preferably lower than the T1 energy level (T FG ).

[0214] In particular, at the T1 level (T FG ) is lower than the T1 energy level (T FH ), it is preferred that the weight ratio of the guest material 121 to the host material 122 is lower than that of the host material 122. Specifically, the weight ratio of the guest material 121 to the host material 122 is preferably greater than 0 and less than 0.05. This can reduce the probability of carrier recombination in the guest material 121. In addition, the T1 energy level (T FH ) to the T1 level (T FG )'s energy transfer probability.

[0215] In addition, the host material 122 may be composed of a single compound or a plurality of compounds.

[0216] In addition, when the light-emitting unit 106 and the light-emitting unit 108 each have a guest material having a different light-emitting color, the light emitted from the light-emitting layer 120 preferably has a light emission peak closer to the shorter wavelength side than the light emitted from the light-emitting layer 170. A light-emitting element using a material having a high triplet excitation energy level tends to deteriorate rapidly in brightness. Therefore, by using TTA for a light-emitting layer that emits light of a short wavelength, a light-emitting element with less brightness degradation can be provided.

[0217] <Structural Example 2 of Light Emitting Element> Figure 4A is a schematic cross-sectional view of the light emitting element 252 .

[0218] As with the above-mentioned light emitting element 250, Figure 4A The light emitting element 252 shown includes a plurality of light emitting units (in Figure 4A 106 and the light-emitting unit 110). At least one of the light-emitting units has the same structure as the EL layer 100. Note that the light-emitting unit 106 and the light-emitting unit 110 may have the same structure or different structures.

[0219] In addition, Figure 4A In the light-emitting element 252 shown, the light-emitting unit 106 and the light-emitting unit 110 are stacked, and the charge generation layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 110. For example, the EL layer 100 is preferably used for the light-emitting unit 106.

[0220] In addition, the light-emitting element 252 includes a light-emitting layer 140 and a light-emitting layer 170. In addition, the light-emitting unit 106 includes 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. In addition, the light-emitting unit 110 includes 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.

[0221] In addition, by applying the structure described in Embodiment 1 to at least one of a plurality of units, a light-emitting element having high light extraction efficiency and reduced driving voltage can be provided.

[0222] like Figure 4B As shown, the light-emitting layer 140 included in the light-emitting unit 110 includes a guest material 141 and a host material 142. In addition, the host material 142 includes an organic compound 142_1 and an organic compound 142_2. The guest material 141 included in the light-emitting layer 140 is described below as a phosphorescent material.

[0223] 《Luminescence mechanism of luminescent layer 140》 Next, the light emitting mechanism of the light emitting layer 140 will be described below.

[0224] The organic compound 142_1 and the organic compound 142_2 in the light-emitting layer 140 form an exciplex.

[0225] The combination of the organic compound 142_1 and the organic compound 142_2 may be any combination as long as they can form an exciplex, and preferably, one of the organic compounds is a compound having a hole-transporting property and the other is a compound having an electron-transporting property.

[0226] Figure 4C The energy level correlation of the organic compound 142_1, the organic compound 142_2, and the guest material 141 in the light-emitting layer 140 is shown below. Figure 4C The records and figure marks in .

[0227] Guest (141): Guest material 141 (phosphorescent material) Host (142_1): Organic compound 142_1 (host material) Host (142_2): Organic compound 142_2 (host material) ·T PG : T1 energy level of guest material 141 (phosphorescent material) ·S PH1 : S1 level of organic compound 142_1 (host material) ·T PH1: T1 level of organic compound 142_1 (host material) ·S PH2 : S1 level of organic compound 142_2 (host material) ·T PH2 : T1 level of organic compound 142_2 (host material) ·S PE : S1 energy level of the exciplex ·T PE : T1 energy level of the exciplex

[0228] The organic compound 142_1 forms an exciplex with the organic compound 142_2. The S1 energy level (S PE ) and T1 level (T PE ) become adjacent energies (refer to Figure 4C Path E3).

[0229] When one of the organic compound 142_1 and the organic compound 142_2 receives a hole and the other receives an electron, an exciplex is rapidly formed. Alternatively, when one of the organic compounds 142_1 and 142_2 is in an excited state, an exciplex is rapidly formed by interacting with the other. As a result, most of the excitons in the light-emitting layer 140 exist as exciplexes. The excitation energy level (S PE or T PE ) is lower than the S1 level (S PH1 and S PH2 ) is low, the excited state of the host material 142 can be formed with lower excitation energy. As a result, the driving voltage of the light-emitting element can be reduced.

[0230] Then, by adding the S PE and T PE The energy of both sides is transferred to the T1 level of the guest material 141 (phosphorescent material) to obtain light emission (refer to Figure 4C Paths E4, E5).

[0231] The T1 energy level of the exciplex (T PE ) is preferably higher than the T1 energy level (T PG ) is high. Thus, the singlet excitation energy and triplet excitation energy of the generated exciplex can be increased from the S1 level (S PE ) and T1 level (T PE ) is transferred to the T1 level (T PG ).

[0232] In order to efficiently transfer the excitation energy from the exciplex to the guest material 141, the T1 energy level (T PE ) is preferably equal to or lower than the T1 level (T PH1 and T PH2 ). Thus, quenching of triplet excitation energy of the exciplex by each organic compound (the organic compound 142_1 and the organic compound 142_2) is unlikely to occur, and energy transfer from the exciplex to the guest material 141 occurs efficiently.

[0233] In order to efficiently form an exciplex with the organic compound 142_1, it is preferred that the HOMO energy level of one of the organic compound 142_1 and the organic compound 142_2 is higher than the HOMO energy level of the other, and the LUMO energy level of one of the organic compound 142_1 and the organic compound 142_2 is higher than the LUMO energy level of the other. For example, when the organic compound 142_1 has a hole transport property and the organic compound 142_2 has an electron transport property, it is preferred that the HOMO energy level of the organic compound 142_1 is higher than the HOMO energy level of the organic compound 142_2 and the LUMO energy level of the organic compound 142_1 is higher than the LUMO energy level of the organic compound 142_2. Alternatively, when the organic compound 142_2 has a hole transport property and the organic compound 142_1 has an electron transport property, it is preferred that the HOMO energy level of the organic compound 142_2 is higher than the HOMO energy level of the organic compound 142_1 and the LUMO energy level of the organic compound 142_2 is higher than the LUMO energy 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 further 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 further preferably 0.2 eV or more.

[0234] When the combination of the organic compound 142_1 and the organic compound 142_2 is a combination of a compound having a hole transport property and a compound having an electron transport property, the carrier balance can be easily controlled by adjusting the mixing ratio. Specifically, it is preferred that the compound having a hole transport property: the compound having an electron transport property is in the range of 1:9 to 9:1 (weight ratio). In addition, when having this structure, the carrier balance can be easily controlled, thereby also being able to easily control the carrier recombination region.

[0235] When the light-emitting layer 140 has the above structure, light emission from the guest material 141 (phosphorescent material) in the light-emitting layer 140 can be obtained efficiently.

[0236] In this specification, the process of the above-mentioned path E3 to E5 is sometimes referred to as ExTET (Exciplex-Triplet Energy Transfer). In other words, in the light-emitting layer 140, the excitation energy is supplied from the exciplex to the guest material 141. In this case, it is not necessary to make the excitation energy from T PE To S PE The efficiency of anti-system crossing and the PE The luminescence quantum yield is high, so more materials can be selected.

[0237] Preferably, the light emitted from the light emitting layer 170 has a light emission peak at a shorter wavelength than the light emitted from the light emitting layer 140. A light emitting element using a phosphorescent material that emits light with a short wavelength tends to deteriorate rapidly in brightness. Therefore, by using fluorescent light emission as the light emission with a short wavelength, a light emitting element with less brightness degradation can be provided.

[0238] <Examples of Materials That Can Be Used for the Light Emitting Layer> Next, materials that can be used for the light-emitting layer 120 , the light-emitting layer 140 , and the light-emitting layer 170 are described.

[0239] 《Materials that can be used for the light-emitting layer 120》 In the light-emitting layer 120, the weight ratio of the host material 122 is the largest, and the guest material 121 (fluorescent material) is dispersed in the host material 122. Preferably, the S1 energy level of the host material 122 is higher than the S1 energy level of the guest material 121 (fluorescent material), and the T1 energy level of the host material 122 is lower than the T1 energy level of the guest material 121 (fluorescent material).

[0240] In the light-emitting layer 120, the guest material 121 is not particularly limited, but anthracene derivatives, tetracene derivatives, The fluorescent compounds described in Embodiment 1 can be appropriately used, for example, derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, phenothiazine derivatives, and the like.

[0241] Although there is no particular limitation on the material of the host material 122 that can be used in the light-emitting layer 120, examples thereof include tris(8-hydroxyquinoline)aluminum(III) (abbreviated as Alq), tris(4-methyl-8-hydroxyquinoline)aluminum(III) (abbreviated as Almq3), bis(10-hydroxybenzo[h]quinoline)beryllium(II) (abbreviated as BeBq2), bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum(III) (abbreviated as BAlq), and bis(10-hydroxybenzo[h]quinoline)beryllium(II) (abbreviated as BeBq2). (8-Hydroxyquinoline) zinc (II) (abbreviated as Znq), bis[2-(2-benzoxazolyl) phenol] zinc (II) (abbreviated as ZnPBO), bis[2-(2-benzothiazolyl) phenol] zinc (II) (abbreviated as ZnBTZ) and other metal complexes; 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviated as OXD-7), 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviated as TAZ), 2,2',2"-(1,3,5-phenyltriyl)tris(1-phenyl-1H-benzimidazole) (abbreviated as TPBI), bathophenanthroline (abbreviated as BPhen), bathocuproin (abbreviated as BCP), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviated as CO11), etc. cyclic compounds; aromatic amine compounds such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), 4,4'-bis[N-(spiro-9,9'-bifluorene-2-yl)-N-phenylamino]biphenyl (abbreviated as BSPB). In addition, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, Derivatives, dibenzo[g,p] Condensed polycyclic aromatic compounds such as derivatives. Specifically, 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthracenyl)triphenylamine (abbreviation: DPhPA), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthracenyl)triphenylamine (abbreviation: YGAPA), N,9-diphenyl-N -[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole-3-amine (abbreviated as: PCAPA), N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthracenyl)phenyl]phenyl}-9H-carbazole-3-amine (abbreviated as: PCAPBA), N,9-diphenyl-N-(9,10-diphenyl-2-anthracenyl)-9H-carbazole-3-amine (abbreviated as: 2PCAPA), 6,12-dimethoxy-5,11-diphenyl N,N,N',N',N",N",N"',N"'-octaphenyldibenzo[g,p] -2,7,10,15-tetramine (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'-anthracene (abbreviation: BANT), 9,9'-(stilbene-3,3'-diyl)phenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl)phenanthrene (abbreviation: DPNS2) and 3,3',3"-(benzene-1,3,5-triyl)tripyrene (abbreviation: TPB3), etc. In addition, one or more substances having an energy gap larger than the energy gap of the above-mentioned guest material 121 can be selected from these substances and known substances.

[0242] The light-emitting layer 120 may also be formed of two or more layers. For example, when the light-emitting layer 120 is formed by stacking a first light-emitting layer and a second light-emitting layer in sequence from the hole transport layer side, a substance having a hole transport property may be used as a main material of the first light-emitting layer, and a substance having an electron transport property may be used as a main material of the second light-emitting layer.

[0243] In the light-emitting layer 120 , the host material 122 may be composed of one compound or a plurality of compounds. Alternatively, the light-emitting layer 120 may include a material other than the host material 122 and the guest material 121 .

[0244] 《Materials that can be used for the light-emitting layer 140》 In the material weight ratio of the light emitting layer 140, the host material 142 accounts for the largest proportion, and the guest material 141 (phosphorescent material) is dispersed in the host material 142. The T1 energy level of the host material 142 (organic compound 142_1 and organic compound 142_2) of the light emitting layer 140 is preferably higher than the T1 energy level of the guest material 141.

[0245] As the organic compound 142_1, in addition to zinc and aluminum 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. can be cited. As other examples, aromatic amines or carbazole derivatives can be cited. Specifically, the electron transport material and the hole transport material shown in Embodiment 1 can be used.

[0246] As the organic compound 142_2, a material that can form an exciplex in combination with the organic compound 142_1 is preferably used. Specifically, the electron transport material and the hole transport material shown in Embodiment 1 can be used. At this time, the organic compound 142_1, the organic compound 142_2 and the guest material 141 (phosphorescent material) are preferably selected in such a way that the emission peak of the exciplex formed by the organic compound 142_1 and the organic compound 142_2 overlaps with the absorption band (specifically, the absorption band on the longest wavelength side) of the triple MLCT (charge transfer from metal to ligand) transition of the guest material 141 (phosphorescent material). Thus, a light-emitting element with significantly improved luminous efficiency can be realized. Note that when a thermally activated delayed fluorescent material is used instead of a phosphorescent material, the absorption band on the longest wavelength side is preferably a singlet absorption band.

[0247] As guest material 141 (phosphorescent material), iridium, rhodium, platinum organic metal complexes or metal complexes can be cited, among which organic iridium complexes, such as iridium ortho-metal complexes, are preferred. As ortho-metallated ligands, 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands or isoquinoline ligands can be cited. As metal complexes, platinum complexes with porphyrin ligands can be cited. Specifically, the materials exemplified as guest material 132 in embodiment 1 can be used.

[0248] As the luminescent material included in the luminescent layer 140, a material capable of converting triplet excitation energy into luminescence can be used. As the material capable of converting triplet excitation energy into luminescence, in addition to phosphorescent materials, thermally activated delayed fluorescent materials can be cited. Therefore, the description of the phosphorescent material can be regarded as the description of the thermally activated delayed fluorescent material.

[0249] The material showing thermally activated delayed fluorescence may be a material that can generate a singlet excited state from a triplet excited state by antisystem crossing alone, or may be composed of a plurality of materials that form an exciplex (also called an exciplex).

[0250] When the thermally activated delayed fluorescent material is composed of one material, specifically, the thermally activated delayed fluorescent material described in Embodiment Mode 1 can be used.

[0251] When a thermally activated delayed fluorescent material is used as a host material, it is preferred to use a combination of two compounds that form an exciplex. In this case, it is particularly preferred to use a combination of the compound that easily accepts electrons and the compound that easily accepts holes, which form an exciplex.

[0252] 《Materials that can be used for the light-emitting layer 170》 As a material that can be used for the light-emitting layer 170 , the materials that can be used for the light-emitting layer described in Embodiment 1 can be applied. Thus, a light-emitting element with high light emission efficiency can be manufactured.

[0253] In addition, there is no limitation on the luminescent colors of the luminescent materials included in the luminescent layer 120, the luminescent layer 140, and the luminescent layer 170, and they may be the same or different. The luminescence from each material is mixed and extracted to the outside of the element, so that, for example, when the two luminescent colors are in a complementary relationship, the luminescent element can provide white light. When considering the reliability of the luminescent element, the luminescent peak wavelength of the luminescent material included in the luminescent layer 120 is preferably shorter than that of the luminescent material included in the luminescent layer 170.

[0254] Alternatively, the light-emitting unit 106 , the light-emitting unit 108 , the light-emitting unit 110 , and the charge generation layer 115 may be formed by evaporation (including vacuum evaporation), inkjet, coating, gravure printing, or the like.

[0255] The structure described in this embodiment mode can be used in combination with the structures described in other embodiment modes as appropriate.

[0256] (Implementation method 3) Figure 5A is a top view showing a light emitting device, Figure 5B is along Figure 5AAB and CD cut cross-sectional view in FIG. The light-emitting device includes a driving circuit portion (source side driving circuit) 601 for controlling the light emission of the light-emitting element, a pixel portion 602, and a driving circuit portion (gate side driving circuit) 603 indicated by a dotted line. In addition, reference numeral 604 is a sealing substrate, reference numeral 625 is a desiccant, reference numeral 605 is a sealant, and the inside surrounded by the sealant 605 is a space 607.

[0257] In addition, the guide wiring 608 is a wiring for transmitting signals input to the source side driving circuit 601 and the gate side driving circuit 603, and receives a video signal, a clock signal, a start signal, a reset signal, etc. from an FPC (flexible printed circuit) 609 used as an external input terminal. In addition, although only the FPC is shown here, the FPC may also be installed with a printed wiring board (PWB). The light-emitting device in this specification includes not only the light-emitting device body, but also a light-emitting device installed with an FPC or a PWB.

[0258] Next, refer to Figure 5B The cross-sectional structure of the light emitting device is described below. A driver circuit portion and a pixel portion are formed over an element substrate 610 , and a source-side driver circuit 601 as the driver circuit portion and one pixel in the pixel portion 602 are shown here.

[0259] In addition, in the source side driving circuit 601, a CMOS circuit combining an n-channel TFT 623 and a p-channel TFT 624 is formed. In addition, the driving circuit can also be formed using various CMOS circuits, PMOS circuits, or NMOS circuits. In addition, in this embodiment, although a driver-integrated type in which the driving circuit is formed on the substrate is shown, this structure does not necessarily have to be adopted, and the driving circuit can also be formed outside instead of being formed on the substrate.

[0260] The pixel portion 602 is formed of a pixel including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain of the current control TFT 612. An insulator 614 is formed to cover the end of the first electrode 613. The insulator 614 can be formed using a positive photosensitive resin film.

[0261] In order to improve the coverage of the film formed on the insulator 614, the upper end or the lower end of the insulator 614 is formed into a curved surface having a curvature. For example, when a photosensitive acrylic resin is used as the material of the insulator 614, it is preferable to form a curved surface only at the upper end of the insulator 614. The curvature radius of the curved surface is 0.2 μm or more and 0.3 μm or less. In addition, as the insulator 614, a negative photosensitive material or a positive photosensitive material can be used.

[0262] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, as a material of the first electrode 613 used as an anode, a material having a large work function is preferably used. For example, in addition to a single-layer film 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, or a Pt film, a stacked layer composed of a titanium nitride film and a film containing aluminum as a main component, and a three-layer structure composed of a titanium nitride film, a film containing aluminum as a main component, and a titanium nitride film can be used. Note that when a stacked-layer structure is used, wiring resistance is also low, good ohmic contact can be obtained, and it can be used as an anode.

[0263] The EL layer 616 is formed by various methods such as vapor deposition using a vapor deposition mask, inkjet, and spin coating. As a material constituting the EL layer 616, a low molecular compound or a high molecular compound (including an oligomer and a dendrimer) may be used.

[0264] In addition, as a material of the second electrode 617 formed on the EL layer 616 and serving as a cathode, a material having a small work function (such as Al, Mg, Li, Ca, or alloys and compounds thereof, MgAg, MgIn, AlLi, etc.) is preferably used. Note that when light generated in the EL layer 616 is transmitted through the second electrode 617, a stacked layer composed of a metal thin film with a reduced thickness and a transparent conductive film (such as 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.) is preferably used as the second electrode 617.

[0265] In addition, a light-emitting element 618 is formed by a first electrode 613, an EL layer 616, and a second electrode 617. The light-emitting element 618 preferably has a structure described in Embodiment Mode 1 or Embodiment Mode 2. In addition, the pixel portion includes a plurality of light-emitting elements, and the light-emitting device of this embodiment mode may include both a light-emitting element having the structure described in Embodiment Mode 1 or Embodiment Mode 2 and a light-emitting element having another structure.

[0266] Furthermore, by bonding the sealing substrate 604 and the element substrate 610 together using the sealant 605, a light emitting element 618 is provided in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. In addition, the space 607 is filled with a filler, and in addition to being filled with an inert gas (nitrogen, argon, etc.), it is sometimes filled with a resin or a dry material, or both a resin and a dry material.

[0267] As the sealant 605, epoxy resin or glass powder is preferably used. In addition, these materials are preferably materials that do not allow moisture and oxygen to pass through as much as possible. In addition, as a material for sealing the substrate 604, in addition to a glass substrate and a quartz substrate, a plastic substrate composed of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester or acrylic resin can also be used.

[0268] By the above method, a light-emitting device using the light-emitting element described in Embodiment Mode 1 and Embodiment Mode 2 can be obtained.

[0269] <Structural Example 1 of Light Emitting Device> FIG. 6 shows, as an example of a light-emitting device, an example of a light-emitting device in which a light-emitting element that emits white light and a coloring layer (color filter) are formed.

[0270] Fig. 6A Shown are a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a driving circuit portion 1041, a first electrode 1024W, 1024R, 1024G, 1024B of the light-emitting element, a partition wall 1026, an EL layer 1028, a second electrode 1029 of the light-emitting element, a sealing substrate 1031, a sealant 1032, and the like.

[0271] In addition, Fig. 6A and Figure 6B In the embodiment, the coloring layers (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) are provided on the transparent substrate 1033. In addition, a black layer (black matrix) 1035 may be provided. The transparent substrate 1033 provided with the coloring layers and the black layer is aligned and fixed on the substrate 1001. In addition, the coloring layers and the black layer are covered by the covering layer 1036. In addition, Fig. 6A It shows that light does not pass through the coloring layer but is transmitted to the outside luminous layer, and light passes through the coloring layers of each color and is transmitted to the outside luminous layer. The light that does not pass through the coloring layer becomes white light, and the light that passes through the coloring layer becomes red light, blue light, and green light, so that an image can be presented with pixels of four colors.

[0272] Figure 6B An example is shown in which a red coloring layer 1034R, a green coloring layer 1034G, and a blue coloring layer 1034B are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. Figure 6B As shown, a coloring layer may be provided between the substrate 1001 and the sealing substrate 1031.

[0273] Although the light-emitting device described above has a structure in which light is emitted from the substrate 1001 side on which a TFT is formed (bottom emission type), a light-emitting device in which light is emitted from the sealing substrate 1031 side (top emission type) may also be used.

[0274] <Structural Example 2 of Light Emitting Device> Figure 7 1001 is a cross-sectional view of a top-emitting light-emitting device. In this case, a substrate that does not allow light to pass through can be used as the substrate 1001. The process until the connection electrode for connecting the TFT and the anode of the light-emitting element is manufactured is performed in the same manner as the bottom-emitting light-emitting device. Then, a third interlayer insulating film 1037 is formed in a manner covering the electrode 1022. The third interlayer insulating film 1037 may also have a planarization function. The third interlayer insulating film 1037 may be formed using the same material as the second interlayer insulating film 1021 or various other materials.

[0275] Although the first lower electrodes 1025W, 1025R, 1025G, and 1025B of the light-emitting elements are all anodes here, they may also be cathodes. Figure 7 In the top emission type light-emitting device shown, the lower electrodes 1025W, 1025R, 1025G, and 1025B are preferably reflective electrodes. In addition, the second electrode 1029 preferably has the function of emitting light and transmitting light. In addition, a microcavity structure is preferably used between the second electrode 1029 and the lower electrodes 1025W, 1025R, 1025G, and 1025B to amplify light of a specific wavelength. The structure of the EL layer 1028 is the structure described in Embodiment 2, and an element structure capable of obtaining white light emission is used.

[0276] exist Fig. 6A , Figure 6B and Figure 7 In the embodiment of the present invention, a structure of an EL layer capable of obtaining white light emission may be realized by using a plurality of light-emitting layers or a plurality of light-emitting units. Note that the structure for obtaining white light emission is not limited to this.

[0277] In adopting Figure 7 In the case of the top emission structure shown, a sealing substrate 1031 provided with a coloring layer (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) can be used for sealing. A black layer (black matrix) 1035 located between pixels can be provided on the sealing substrate 1031. The coloring layer (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) and the black layer (black matrix) can also be covered by a covering layer. In addition, a light-transmitting substrate is used as the sealing substrate 1031.

[0278] In addition, although the example of full-color display with four colors of red, green, blue, and white is shown here, it is not limited to this, and full-color display with three colors of red, green, and blue can also be performed. In addition, full-color display with four colors of red, green, blue, and yellow can also be performed.

[0279] By the above method, a light-emitting device using the light-emitting element described in Embodiment Mode 1 and Embodiment Mode 2 can be obtained.

[0280] In addition, this embodiment mode can be combined with other embodiment modes as appropriate.

[0281] (Implementation 4) In this embodiment, an electronic device which is one embodiment of the present invention is described.

[0282] Because one embodiment of the present invention uses an organic EL light-emitting element, an electronic device having a flat surface, high luminous efficiency and high reliability can be manufactured. In addition, one embodiment of the present invention can manufacture an electronic device having a curved surface, high luminous efficiency and high reliability. In addition, one embodiment of the present invention can form an electronic device having flexibility, high luminous efficiency and high reliability.

[0283] Examples of the electronic equipment include television sets; desktop or notebook personal computers; displays for computers, etc.; digital cameras; digital video cameras; digital photo frames; mobile phones; portable game consoles; portable information terminals; sound reproduction devices; and large-scale game machines such as pinball machines.

[0284] Furthermore, the light emitting device of one embodiment of the present invention can achieve high visibility regardless of the intensity of external light, and is therefore suitable for portable electronic devices, wearable electronic devices, e-book readers, and the like.

[0285] Fig. 8A and Figure 8B The illustrated portable information terminal 900 includes a housing 901 , a housing 902 , a display portion 903 , a hinge portion 905 , and the like.

[0286] The housing 901 and the housing 902 are connected together by a hinge portion 905. The portable information terminal 900 can be opened from a folded state ( Fig. 8A ) is converted into Figure 8B As a result, the portability is good when carrying, and the visibility is high when using due to the large display area.

[0287] The portable information terminal 900 is provided with a flexible display portion 903 across a housing 901 and a housing 902 connected by a hinge portion 905 .

[0288] The light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 903. Thus, the portable information terminal can be manufactured with a high yield.

[0289] The display portion 903 can display at least one of document information, static images, dynamic images, etc. When the document information is displayed on the display portion, the portable information terminal 900 can be used as an electronic book reader.

[0290] When the portable information terminal 900 is unfolded, the display unit 903 is maintained in a greatly curved state. For example, the display unit 903 may be maintained in a manner including a portion curved with a radius of curvature of not less than 1 mm and not more than 50 mm, preferably not less than 5 mm and not more than 30 mm. A portion of the display unit 903 is continuously provided with pixels across the housing 901 and the housing 902, thereby enabling curved display.

[0291] The display portion 903 is used as a touch panel and can be operated with a finger, a stylus pen, or the like.

[0292] The display unit 903 is preferably formed of a flexible display, so that a continuous display can be performed across the housing 901 and the housing 902. In addition, the housing 901 and the housing 902 can also be provided with displays respectively.

[0293] In order to prevent the angle formed by the housing 901 and the housing 902 from exceeding a predetermined angle when the portable information terminal 900 is unfolded, the hinge portion 905 preferably has a locking mechanism. For example, the locking angle (at which the portable information terminal 900 cannot be further opened) is preferably greater than 90° and less than 180°, and typically can be 90°, 120°, 135°, 150°, or 175°, etc. Thus, the convenience, safety, and reliability of the portable information terminal 900 can be improved.

[0294] When the hinge portion 905 has the above-described locking mechanism, it is possible to suppress application of an excessive force to the display portion 903, thereby preventing damage to the display portion 903. Thus, a highly reliable portable information terminal can be realized.

[0295] Housing 901 and housing 902 may also include a power button, operation buttons, an external connection port, a speaker, a microphone, and the like.

[0296] Either the housing 901 or the housing 902 may be provided with a wireless communication module, and data may be sent and received via a computer network such as the Internet, a local area network (LAN), or Wireless Fidelity (Wi-Fi: a registered trademark).

[0297] Figure 8CThe illustrated portable information terminal 910 includes a housing 911 , a display portion 912 , operation buttons 913 , an external connection port 914 , a speaker 915 , a microphone 916 , a camera 917 , and the like.

[0298] The light-emitting device manufactured by one embodiment of the present invention can be used for the display portion 912. Thus, the portable information terminal can be manufactured with a high yield.

[0299] The portable information terminal 910 includes a touch sensor in the display portion 912. By touching the display portion 912 with a finger or a stylus pen, various operations such as making a call and inputting text can be performed.

[0300] Furthermore, by operating the operation button 913, it is possible to turn the power on and off or switch the type of image displayed on the display portion 912. For example, the e-mail composition screen can be switched to the main menu screen.

[0301] In addition, by providing a detection device such as a gyro sensor or an acceleration sensor inside the portable information terminal 910, the direction (vertical or horizontal) of the portable information terminal 910 can be determined, and the screen display direction of the display unit 912 can be automatically switched. In addition, the screen display direction can also be switched by touching the display unit 912, operating the operation button 913, or inputting a sound using the microphone 916.

[0302] The portable information terminal 910 has one or more functions selected from a telephone, a notebook, and an information reading device, for example. Specifically, the portable information terminal 910 can be used as a smart phone. The portable information terminal 910 can execute various applications such as mobile phone, e-mail, article reading and editing, music playing, animation playing, network communication, computer games, etc.

[0303] Fig.8D The camera 920 shown includes a housing 921 , a display portion 922 , operation buttons 923 , a shutter button 924 , etc. In addition, the camera 920 is equipped with a detachable lens 926 .

[0304] The light-emitting device manufactured by one embodiment of the present invention can be used for the display portion 922. Thus, the camera can be manufactured with a high yield.

[0305] Here, although the camera 920 has a structure in which the lens 926 can be detached from the housing 921 and replaced, the lens 926 and the housing 921 may be formed integrally.

[0306] The camera 920 can capture a still image or a moving image by pressing the shutter button 924. Alternatively, the display portion 922 may have a touch panel function, and the image may be captured by touching the display portion 922.

[0307] In addition, the camera 920 may further include a flash device and a viewfinder that are separately installed. In addition, these components may also be assembled in the housing 921.

[0308] 9A to 9E 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 (which has a function of measuring the following factors: force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electricity, radiation, flow, humidity, inclination, vibration, smell or infrared), a microphone 9008, etc.

[0309] The light-emitting device manufactured by one embodiment of the present invention can be used for the display portion 9001. Thus, electronic devices can be manufactured with a high yield.

[0310] 9A to 9E The electronic device shown may have various functions. For example, it may have the following functions: display various information (static images, dynamic images, text images, etc.) on the display unit; touch panel; display calendar, date or time, etc.; control processing by using various software (programs); perform wireless communication; connect to various computer networks by using wireless communication functions; send or receive various data by using wireless communication functions; read programs or data stored in recording media and display them on the display unit, etc. Note that 9A to 9E The functions of the electronic device shown are not limited to the above functions, and the electronic device may also have other functions.

[0311] Fig. 9A is a perspective view showing a wristwatch-type portable information terminal 9200, Fig. 9B It is a perspective view showing a wristwatch-type portable information terminal 9201.

[0312] Fig. 9AThe portable information terminal 9200 shown can execute various applications such as mobile phones, e-mails, article reading and editing, music playing, network communication, computer games, etc. In addition, the display surface of the display unit 9001 is curved, and display can be performed along its curved display surface. In addition, the portable information terminal 9200 can perform short-range wireless communication based on communication standards. For example, by communicating with a headset that can perform wireless communication, a hands-free call can be made. In addition, the portable information terminal 9200 includes a connection terminal 9006, and data can be exchanged directly with other information terminals through a connector. In addition, charging can also be performed through the connection terminal 9006. In addition, the charging action can also be performed using wireless power supply instead of through the connection terminal 9006.

[0313] Fig. 9B The portable information terminal 9201 shown is Fig. 9A The portable information terminal shown in the figure is different in that the display surface of the display portion 9001 is not curved. In addition, the display portion of the portable information terminal 9201 has a non-rectangular shape (in Fig. 9B (circular in shape).

[0314] FIG. 9C to FIG. 9E 9202 is a perspective view showing a foldable portable information terminal. Fig. 9C is a perspective view of the portable information terminal 9202 in an unfolded state. Fig.9D This is a perspective view of a state in which the portable information terminal 9202 is being converted from one of the unfolded state and the folded state to the other. Fig.9E This is a perspective view of the portable information terminal 9202 in a folded state.

[0315] The portable information terminal 9202 is easy to carry when folded, and has a large seamless display area when unfolded, so the display is easy to see at a glance. The display unit 9001 included in the portable information terminal 9202 is supported by three housings 9000 connected by hinges 9055. The portable information terminal 9202 can be reversibly changed from the unfolded state to the folded state by bending the two housings 9000 through the hinges 9055. For example, the portable information terminal 9202 can be bent with a curvature radius of 1 mm or more and 150 mm or less.

[0316] This embodiment mode can be combined with other embodiment modes as appropriate.

[0317] (Implementation method 5) In this embodiment, referring to FIGS. 10 and Fig.11Examples of cases where the light-emitting element of one embodiment of the present invention is applied to various lighting devices will be described. By using the light-emitting element of one embodiment of the present invention, a lighting device with high light emission efficiency and high reliability can be manufactured.

[0318] By forming the light-emitting element of one embodiment of the present invention on a flexible substrate, an electronic device or a lighting device including a light-emitting region having a curved surface can be realized.

[0319] Furthermore, a light-emitting device to which the light-emitting element of one embodiment of the present invention is applied can also be applied to lighting for an automobile provided on a windshield, a ceiling, or the like.

[0320] Fig. 10A A perspective view showing one face of the multi-function terminal 3500, Fig. 10B This is a perspective view showing another surface of the multifunctional terminal 3500. In the multifunctional terminal 3500, a display unit 3504, a camera 3506, a lighting unit 3508, and the like are incorporated into a housing 3502. The light emitting device of one embodiment of the present invention can be used for the lighting unit 3508.

[0321] The lighting 3508 including the light emitting device of one embodiment of the present invention is used as a surface light source. Therefore, unlike a point light source represented by an LED (Light Emitting Diode), light emission with low directivity can be obtained. For example, when the lighting 3508 and the camera 3506 are used in combination, the camera 3506 can be used to take pictures while lighting or flashing the lighting 3508. Because the lighting 3508 has the function of a surface light source, a picture can be obtained as if it were taken under natural light.

[0322] Notice, Fig. 10A and Fig. 10B The multifunctional terminal 3500 shown is 9A to 9C The electronic device shown may likewise have a variety of functions.

[0323] In addition, a speaker, a sensor (the sensor has the function of measuring the following factors: force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electricity, radiation, flow, humidity, inclination, vibration, smell or infrared), a microphone, etc. can be provided inside the housing 3502. In addition, by providing a detection device having a sensor for detecting inclination such as a gyroscope and an acceleration sensor inside the multi-function terminal 3500, the direction (vertical or horizontal) of the multi-function terminal 3500 can be determined and the screen display of the display unit 3504 can be automatically switched.

[0324] In addition, the display portion 3504 can also be used as an image sensor. For example, by touching the display portion 3504 with a palm or a finger, a palm print or a fingerprint can be photographed, thereby enabling personal identification. In addition, by providing a backlight or a sensing light source that emits near-infrared light in the display portion 3504, it is also possible to photograph finger veins, palm veins, etc. Note that the light-emitting device of one embodiment of the present invention can be applied to the display portion 3504.

[0325] Fig. 10C The figure shows a perspective view of a security light 3600. The light 3600 includes a lighting 3608 on the outside of a housing 3602, and a speaker 3610 and the like are incorporated into the housing 3602. The light emitting element of one embodiment of the present invention can be used for the lighting 3608.

[0326] The lamp 3600 can emit light when the lighting 3608 is grasped or held, for example. In addition, an electronic circuit capable of controlling the light-emitting mode of the lamp 3600 can be provided inside the housing 3602. As the electronic circuit, for example, a circuit capable of realizing single or intermittent multiple light emission or a circuit capable of adjusting the light emission amount by controlling the light emission current value can be used. In addition, a circuit that emits a loud alarm sound from the speaker 3610 while the lighting 3608 emits light can also be assembled.

[0327] Since the light 3600 can emit light in all directions, it can emit light or emit light and sound to frighten criminals, etc. In addition, the light 3600 can have a function of having a camera function by including a camera such as a digital still camera.

[0328] Fig.11 This is an example of using a light-emitting element for an indoor lighting device 8501. In addition, since the light-emitting element can be large-area, a large-area lighting device can also be formed. In addition, a lighting device 8502 in which the light-emitting area has a curved surface can be formed by using a shell having a curved surface. The light-emitting element shown in this embodiment is in the form of a thin film, so the design freedom of the shell is high. Therefore, a lighting device that can correspond to various designs can be formed. In addition, a large lighting device 8503 can also be provided on the wall of the room. In addition, a touch sensor can also be provided in the lighting device 8501, the lighting device 8502, and the lighting device 8503 to start or turn off the power.

[0329] In addition, by using the light-emitting element on the surface side of the table, a lighting device 8504 having the function of a table can be provided. In addition, by using the light-emitting element on a part of other furniture, a lighting device having the function of furniture can be provided.

[0330] As described above, by applying the light-emitting device of one embodiment of the present invention, a lighting device and an electronic device can be obtained. Note that the present invention is not limited to the lighting device and the electronic device described in this embodiment, but can be applied to electronic devices in various fields.

[0331] The structure described in this embodiment mode can be implemented in combination with the structures described in other embodiment modes as appropriate. Example 1

[0332] In this example, a manufacturing example of a light-emitting element which is one of electronic devices of one embodiment of the present invention and characteristics of the light-emitting element are described. In addition, an organic compound used for a hole injection layer and a refractive index of the hole injection layer are described. Figure 2A 2 is a cross-sectional view showing the structure of the device manufactured in this example. In addition, the detailed device structure is shown in Table 1. In addition, the structures and abbreviations of the compounds used are shown below.

[0333] [Chemical formula 7]

[0334] [Table 1]

[0335] [Table 2] Comparison light emitting element 1 Comparison light emitting element 2 Comparison light emitting element 3 Comparison of light emitting elements 4 <![CDATA[x1]]> 35 40 45 50

[0336] [Table 3] Light emitting element 5, 9 Light emitting element 6, 10 Light emitting element 7, 11 Light emitting element 8, 12 <![CDATA[x2]]> 0 5 10 15

[0337] <Measurement of refractive index> The refractive index of the organic compound and the hole injection layer 111 used for the comparative light-emitting element 1 to the comparative light-emitting element 4, the light-emitting element 5 to the light-emitting element 8, and the light-emitting element 9 to the light-emitting element 12 was measured. The refractive index was measured at room temperature using a multi-incident angle high-speed spectroscopic ellipsometer (M-2000U) of a rotary compensator type manufactured by JA Woolam. The measurement sample was manufactured by vacuum evaporation on a quartz substrate. n Ordinary and n Extraordinary were measured, and n average was calculated.

[0338] Fig.12 The results of measuring the refractive index of each film for light with a wavelength of 532 nm are shown. Fig.12It can be seen that DBT3P-II used for comparative light-emitting elements 1 to 4 has the highest refractive index. dmCBP used for light-emitting elements 5 to 8 is an organic compound with a low refractive index, that is, n Ordinary is less than 1.75. In addition, TAPC used for light-emitting elements 9 to 12 is an organic compound with a very low refractive index, that is, n Ordinary is less than 1.70.

[0339] In addition, the hole injection layer 111 is required to have hole injecting properties, so it is preferable to include an electron donating material. The hole injection layer 111 of each light emitting element using MoO3 with a high refractive index as an electron donating material is estimated to have a high refractive index. Fig.12 It can be seen that the refractive index of the film formed by adding MoO3 of the hole injection layer 111 of each light-emitting element to each organic compound is slightly greater than the refractive index of each organic compound. That is, by using an organic compound with a low refractive index as the hole injection layer 111, a hole injection layer 111 with a low refractive index can be obtained even if a material with a high refractive index is used as the material having electron donating properties.

[0340] In addition, by Fig.12 It can be seen that the difference between n Ordinary and n Extraordinary of the hole injection layer 111 of each light emitting element is smaller than that of each organic compound film. In other words, the mixed film of MoO3, an electron accepting material, and an organic compound has lower anisotropy than the organic compound film.

[0341] <Manufacturing of Light Emitting Element> <<Manufacturing of Comparative Light-Emitting Elements 1 to 4>> As the electrode 101, a 70 nm thick ITSO film was formed on a glass substrate. In addition, the area of ​​the electrode 101 was 4 mm 2 (2 mm×2 mm) The refractive index (n Ordinary) of the ITSO film for light having a wavelength of 532 nm is 2.07.

[0342] Next, as a hole injection layer 111, 1,3,5-tri-(4-dibenzothienyl)-benzene (abbreviation: DBT3P-II) and MoO3 were co-evaporated on the electrode 101 in a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of x1 nm. Note that the value of x1 varies depending on each light-emitting element, and Table 2 shows the value of x1 in each light-emitting element.

[0343] Next, PCCP was deposited on the hole injection layer 111 to a thickness of 20 nm as the hole transport layer 112 .

[0344] Next, as the light-emitting layer 130 (1), 4,6mCzP2Pm, PCCP and Ir(pbi-diBuCNp)3 (facial isomer: meridional isomer) were deposited on the hole transport layer 112. =3:2 mixture) was co-evaporated in a weight ratio (4,6mCzP2Pm:PCCP:Ir(pbi-diBuCNp)3) of 0.5:0.5:0.1 and a thickness of 20 nm, and then, as the light-emitting layer 130(2), it was co-evaporated in a weight ratio (4,6mCzP2Pm:PCCP:Ir(pbi-diBuCNp)3) of 0.8:0.2:0.1 and a thickness of 20 nm. Note that in the light-emitting layer 130(1) and the light-emitting layer 130(2), Ir(pbi-diBuCNp)3 is a guest material that exhibits phosphorescence.

[0345] Next, 4,6mCzP2Pm was co-evaporated on the light-emitting layer 130(2) to a thickness of 20 nm as the first electron transport layer 118(1). Then, bathophenanthroline (abbreviated as BPhen) was evaporated on the first electron transport layer 118(1) to a thickness of 10 nm as the second electron transport layer 118(2).

[0346] Next, as the electron injection layer 119 , lithium fluoride (LiF) was deposited on the second electron transport layer 118 ( 2 ) to a thickness of 1 nm.

[0347] Next, aluminum (Al) was formed as the electrode 102 on the electron injection layer 119 to a thickness of 200 nm.

[0348] Next, in a glove box with a nitrogen atmosphere, a sealing glass substrate was fixed to a glass substrate on which an organic material was formed using an organic EL sealing agent to seal comparative light-emitting elements 1 to 4. Specifically, the sealing agent was applied around the organic material on the glass substrate on which an organic material was formed, and the substrate and the sealing glass substrate were bonded together, and the sealing agent was applied at 6 J / cm 2 Ultraviolet light having a wavelength of 365 nm was irradiated, and a heat treatment was performed at 80° C. for 1 hour. Comparative Light-Emitting Elements 1 to 4 were obtained through the above steps.

[0349] <<Manufacturing of Light-Emitting Elements 5 to 8>> The difference between the manufacturing process of light-emitting elements 5 to 8 and the comparative light-emitting elements 1 to 4 is only the manufacturing process of the hole injection layer 111, and the other processes are the same as those of comparative light-emitting elements 1 to 4.

[0350] As the hole injection layer 111 (1), dmCBP and MoO3 were co-deposited on the electrode 101 in a weight ratio (dmCBP:MoO3) of 2:0.5 and a thickness of 35 nm, and then DBT3P-II and MoO3 were co-deposited in a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of x2 nm. Note that the value of x2 varies depending on each light-emitting element, and Table 3 shows the value of x2 in each light-emitting element.

[0351] <<Manufacturing of Light-Emitting Elements 9 to 12>> The difference between the manufacturing process of light-emitting elements 9 to 12 and the comparative light-emitting elements 1 to 4 is only the manufacturing process of the hole injection layer 111, and the other processes are the same as those of comparative light-emitting elements 1 to 4.

[0352] As the hole injection layer 111 (1), TAPC and MoO3 were co-evaporated on the electrode 101 in a weight ratio (TAPC:MoO3) of 2:0.5 and a thickness of 35 nm, and then DBT3P-II and MoO3 were co-evaporated in a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of x2 nm. Note that the value of x2 varies depending on each light-emitting element, and Table 3 shows the value of x2 in each light-emitting element.

[0353] <Characteristics of Light Emitting Element> Next, the characteristics of the comparative light-emitting elements 1 to 4 and the light-emitting elements 5 to 12 were measured. In the measurement of brightness and CIE chromaticity, a colorimeter (BM-5A manufactured by Topcon Technohouse) was used, and in the measurement of electroemission spectrum, a multi-channel spectrum analyzer (PMA-11 manufactured by Hamamatsu Photonics Co., Ltd., Japan) was used. The measurement of each light-emitting element was carried out at room temperature (an atmosphere maintained at 23°C).

[0354] Fig.13 The current efficiency-luminance characteristics of the comparative light-emitting element 1, the light-emitting element 5, and the light-emitting element 9 among the manufactured light-emitting elements are shown. Fig.14 The current density-voltage characteristics are shown. Fig.15 The external quantum efficiency-brightness characteristics are shown. Note that Fig.15 The external quantum efficiency shown is the external quantum efficiency when measured from the front direction of the light-emitting element without viewing angle correction. In addition, as the organic compound of the hole injection layer 111, DBT3P-II is used in the comparative light-emitting element 1, dmCBP is used in the light-emitting element 5, and TAPC is used in the light-emitting element 9, and the parts other than the hole injection layer 111 have the same element structure.

[0355] Depend on Fig.14 It can be seen that the comparative light-emitting element 1, the light-emitting element 5, and the light-emitting element 9 have current density-voltage characteristics of comparable magnitude. Therefore, even when an organic compound having a low refractive index is used in the hole injection layer 111, good hole injection characteristics are obtained.

[0356] In addition, by Fig.13 and Fig.15 It can be seen that the comparative light-emitting element 1, the light-emitting element 5 and the light-emitting element 9 have a high current efficiency exceeding 100 cd / A and a high external quantum efficiency exceeding 30%. In addition, the light-emitting element 5 and the light-emitting element 9 using dmCBP and TAPC, which are organic compounds with a low refractive index, for the hole injection layer 111 show higher efficiency than the comparative light-emitting element 1 using DBT3P-II, which is a material with a high refractive index.

[0357] also, Fig.16 Shown at 25mA / cm 2 The emission spectra of light-emitting element 1, light-emitting element 5 and light-emitting element 9 when the current density is made to flow through the light-emitting element 1, light-emitting element 5 and light-emitting element 9. Fig.16 It can be seen that the emission spectra of the comparative light-emitting element 1, the light-emitting element 5 and the light-emitting element 9 have peaks near 515 nm and 550 nm, and the peaks are derived from the light emission of Ir(pbi-diBuCNp) 3 which is the guest material contained in the light-emitting layer 130 .

[0358] In addition, Table 4 shows that 1000 cd / m 2 The device characteristics of the nearby comparative light-emitting elements 1 to 4 and light-emitting elements 5 to 12. The external quantum efficiency shown in Table 4 is the external quantum efficiency after viewing angle correction.

[0359] [Table 4]

[0360] From the above results, it can be seen that the comparative light-emitting elements 1 to 4 and the light-emitting elements 5 to 12 manufactured in this example have good driving voltage and light-emitting efficiency regardless of the structure of the hole injection layer 111 .

[0361] <Relationship between Refractive Index and External Quantum Efficiency of Hole Injection Layer 111> exist Fig.17 In the figure, the relationship between the chromaticity x and the external quantum efficiency of the organic material used for each hole injection layer 111 is represented using the values ​​of each element shown in Table 4. Fig.17In the graph, the values ​​of comparative light-emitting elements 1 to 4 are used as the curve data of "DBT3P-II", the values ​​of light-emitting elements 5 to 8 are used as the curve data of "dmCBP", and the values ​​of light-emitting elements 9 to 12 are used as the curve data of "TAPC". Here, in comparative light-emitting elements 1 to 4 and light-emitting elements 5 to 12, even when the thickness of the hole injection layer 111 is the same, the refractive index is different depending on the organic compound used, and thus the optical path length from the light-emitting region to the substrate of each light-emitting element changes. When the optical path length changes, the external quantum efficiency also changes. Therefore, in order to evaluate 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 of each light-emitting element. However, it is difficult to adjust the thickness of the EL layer when manufacturing the light-emitting element.

[0362] In a light-emitting element using the same light-emitting material, when the optical path length from the light-emitting region to the substrate of each light-emitting element is different, the emission spectrum and chromaticity obtained from the light-emitting element are different. On the other hand, when the same chromaticity is obtained from each light-emitting element, the emission spectrum extracted from each light-emitting element is considered to be the same. That is, when the same chromaticity is obtained from each light-emitting element, the optical path length from the light-emitting region to the substrate of each light-emitting element can be said to be the same. Therefore, focusing on the relationship between the external quantum efficiency and the chromaticity x or the chromaticity y, the relationship between the refractive index of the hole injection layer 111 and the external quantum efficiency can be evaluated.

[0363] from Fig.12 It can be seen that the organic compounds used for the hole injection layer 111 have high refractive indexes in the order of DBT3P-II>dmCBP>TAPC. Fig.17 It can be seen that the lower the refractive index of the organic compound used for the hole injection layer 111, the higher the external quantum efficiency. This is because the light attenuation caused by the evanescent mode is reduced and the light extraction efficiency is improved.

[0364] This shows that, by using an organic compound having a low refractive index in the hole injection layer 111 , a light-emitting element having high light extraction efficiency can be obtained while maintaining hole injection characteristics.

[0365] <Relationship between the Volume Ratio of the Electron Donating Material and the Electron Accepting Material in the Hole Injection Layer 111 and the External Quantum Efficiency> Here, the relationship between the volume ratio of the electron accepting material (MoO3) relative 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 is investigated. In addition, Table 5 shows the detailed element structure. In addition, the structure and abbreviation of the compound used are shown below. Note that for other organic compounds, the above compounds can be referred to.

[0366] [Chemical formula 8]

[0367] [Table 5]

[0368] [Table 6] Light emitting element 13 Light emitting element 14 Light emitting element 15 Light emitting element 16 Light emitting element 17 Light emitting element 18 y 0.25 0.5 1.0 1.5 2 2.5 <![CDATA[Volume ratio of MoO3]]> 0.02 0.05 0.1 0.29 0.33 0.56

[0369] <<Manufacturing of Light Emitting Elements 13 to 18>>> The difference between the manufacturing process of light-emitting elements 13 to 18 and the above-mentioned comparative light-emitting elements 1 to 4 lies only in the manufacturing process of the hole injection layer 111 and the light-emitting layer 130 , and the other processes are the same as those of comparative light-emitting elements 1 to 4 .

[0370] As the hole injection layer 111, DBT3P-II and MoO3 were co-evaporated on the electrode 101 in a weight ratio (DBT3P-II:MoO3) of 3-y:y and a thickness of 40 nm. Note that the value of y varies depending on each light-emitting element, and Table 6 shows the value of y in each light-emitting element. In addition, Table 6 also shows the result of converting the weight ratio into the volume ratio of MoO3.

[0371] Next, as the light-emitting layer 130(1), 4,6mCzP2Pm, PCCP, and Ir(tBuppm)3 were co-deposited on the hole transport layer 112 in a weight ratio (4,6mCzP2Pm:PCCP:Ir(tBuppm)3) of 0.5:0.5:0.075 and a thickness of 20 nm, and then as the light-emitting layer 130(2), they were co-deposited in a weight ratio (4,6mCzP2Pm:PCCP:Ir(tBuppm)3) of 0.8:0.2:0.075 and a thickness of 20 nm. Note that in the light-emitting layer 130(1) and the light-emitting layer 130(2), Ir(tBuppm)3 is a guest material that exhibits phosphorescence.

[0372] <Characteristics of Light Emitting Element> Next, the luminance-external quantum efficiency characteristics of the above-mentioned Light-Emitting Elements 13 to 18 were measured. The measurement was performed by the above-mentioned method.

[0373] Fig.18 Shows 10000cd / m 2 The relationship between the external quantum efficiency and the volume ratio of MoO3 in the hole injection layer 111. Fig.18It can be seen that in the region where the volume ratio of MoO3 relative to the electron-donating substance is greater than 0 and less than 0.3, the external quantum efficiency is relatively high, that is, it shows an efficiency of 24% to 26%, but the efficiency decreases in the region greater than 0.3. This is because: in the region where the volume ratio of MoO3 is greater than 0.3, the refractive index of the hole injection layer 111 becomes larger due to the influence of the electron-accepting substance (MoO3) with a large refractive index, so the light extraction efficiency decreases. 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 substance (MoO3) with a large refractive index is small, and the refractive index of the electron-donating substance whose refractive index is less than that of the electron-accepting substance (MoO3) strongly affects the refractive index of the hole injection layer 111, so that the region has a high light extraction efficiency. That is, by using a hole injection layer 111 with a concentration of MoO3 greater than 0 and less than 0.3, a light-emitting element with high light extraction efficiency can be manufactured. Example 2

[0374] In this embodiment, an example of manufacturing a light-emitting element different from that in Embodiment 1 of an electronic device of one embodiment of the present invention and the characteristics of the light-emitting element are described. In addition, an organic compound used for the hole injection layer 111 and the refractive index of the hole injection layer are described. In addition, Table 7 shows the detailed element structure. The structures and abbreviations of the compounds used are shown below. Note that for other organic compounds, reference can be made to Embodiment 1 above.

[0375] [Chemical formula 9]

[0376] [Table 7]

[0377] [Table 8] Comparison light emitting element 19 Comparison of light emitting elements 20 Comparison of light emitting elements 21 Comparison of light emitting elements 22 <![CDATA[z1]]> 35 40 45 50

[0378] [Table 9] Light emitting elements 23, 27 Light emitting elements 24, 28 Light emitting element 25, 29 Light emitting elements 26, 30 <![CDATA[z2]]> 0 5 10 15

[0379] <Measurement of refractive index> The refractive index of the organic compound used for 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 refractive index was measured in the same manner as in Example 1.

[0380] Fig.19 The results of measuring the refractive index of each film for light with a wavelength of 532 nm are shown. Fig.19It can be seen that DBT3P-II used for comparative light-emitting elements 19 to 22 has the highest refractive index. 9-[3-(9-phenyl-9H-fluorene-9-yl)phenyl]-9H-carbazole (abbreviated as mCzFLP) used for light-emitting elements 23 to 26 is an organic compound with a low refractive index of n Ordinary of 1.75 or less. In addition, 4,4'-[bis(9-phenylfluorene-9-yl)]-triphenylamine (abbreviated as FLP2A) used for light-emitting elements 27 to 30 is an organic compound with a low refractive index of n Ordinary of 1.75 or less.

[0381] In addition, based on the results of Example 1, it can be estimated that the mixed film of mCzFLP or FLP2A and MoO3 in the hole injection layer 111 of light-emitting elements 23 to 30 has the same refractive index as each organic compound, and has a lower refractive index than the mixed film of DBT3P-II and MoO3 in the hole injection layer 111 of comparison light-emitting elements 19 to comparison light-emitting elements 22.

[0382] <Manufacturing of Light Emitting Element> <<Manufacturing of Comparative Light-Emitting Elements 19 to 22>> The difference between the manufacturing process of comparative light-emitting elements 19 to comparative light-emitting elements 22 and the above-mentioned comparative light-emitting elements 1 to comparative light-emitting elements 4 lies only in the manufacturing process of the hole injection layer 111 and the light-emitting layer 130 , and the other processes are the same as those of comparative light-emitting elements 1 to comparative light-emitting elements 4 .

[0383] As the hole injection layer 111, DBT3P-II and MoO3 were co-evaporated on the electrode 101 at a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of z1 nm. Note that the value of z1 varies depending on each light-emitting element, and Table 8 shows the value of z1 in each light-emitting element.

[0384] Next, as the light-emitting layer 130(1), 4,6mCzP2Pm, PCCP, and Ir(ppy)3 were co-deposited on the hole transport layer 112 in a weight ratio (4,6mCzP2Pm:PCCP:Ir(ppy)3) of 0.5:0.5:0.1 and a thickness of 20 nm, and then as the light-emitting layer 130(2), they were co-deposited in a weight ratio (4,6mCzP2Pm:PCCP:Ir(ppy)3) of 0.8:0.2:0.1 and a thickness of 20 nm. Note that in the light-emitting layer 130(1) and the light-emitting layer 130(2), Ir(ppy)3 is a guest material that exhibits phosphorescence.

[0385] <<Manufacturing of Light-Emitting Elements 23 to 26>> The difference between the manufacturing process of light-emitting elements 23 to 26 and the comparative light-emitting elements 19 to 22 mentioned above lies only in the manufacturing process of the hole injection layer 111 , and the other processes are the same as those of the comparative light-emitting elements 19 to 22 .

[0386] As the hole injection layer 111 (1), mCzFLP and MoO3 were co-deposited on the electrode 101 in a weight ratio of 2:0.5 (mCzFLP:MoO3) and a thickness of 35 nm. Then, DBT3P-II and MoO3 were co-deposited in a weight ratio of 2:0.5 (DBT3P-II:MoO3) and a thickness of z2 nm. Note that the value of z2 varies depending on each light-emitting element, and Table 9 shows the value of z2 in each light-emitting element.

[0387] <<Manufacturing of Light-Emitting Elements 27 to 30>> The difference between the manufacturing process of light-emitting elements 27 to 30 and the comparative light-emitting elements 19 to 22 mentioned above lies only in the manufacturing process of the hole injection layer 111 , and the other processes are the same as those of the comparative light-emitting elements 19 to 22 .

[0388] As the hole injection layer 111 (1), FLP2A and MoO3 were co-deposited on the electrode 101 in a weight ratio (FLP2A:MoO3) of 2:0.5 and a thickness of 35 nm. Then, DBT3P-II and MoO3 were co-deposited in a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of z2 nm. Note that the value of z2 varies depending on each light-emitting element, and Table 9 shows the value of z2 in each light-emitting element.

[0389] <Characteristics of Light Emitting Element> Next, the characteristics of the comparative light-emitting elements 19 to 22 and the light-emitting elements 23 to 30 were measured. The measurement was performed in the same manner as in Example 1.

[0390] Fig. 20 The current efficiency-luminance characteristics of the comparative light-emitting element 19, the light-emitting element 23, and the light-emitting element 27 among the manufactured light-emitting elements are shown. Fig.21 The current density-voltage characteristics are shown. Fig. 22 The external quantum efficiency-brightness characteristics are shown. Note that Fig. 22The external quantum efficiency shown is the external quantum efficiency when measured from the front direction of the light-emitting element without viewing angle correction. In addition, as the organic compound of the hole injection layer 111, DBT3P-II is used in the comparative light-emitting element 19, mCzFLP is used in the light-emitting element 23, and FLP2A is used in the light-emitting element 27, and the parts other than the hole injection layer 111 have the same element structure.

[0391] Depend on Fig.21 It is found that the comparative light-emitting element 19, the light-emitting element 23, and the light-emitting element 27 have current density-voltage characteristics of the same degree. Therefore, similarly to Example 1, even when an organic compound with a low refractive index is used in the hole injection layer 111, good hole injection characteristics are obtained.

[0392] In addition, by Fig. 20 and Fig. 22 It can be seen that the comparative light-emitting element 19, the light-emitting element 23, and the light-emitting element 27 have a high current efficiency of about 100 cd / A and a high external quantum efficiency of more than 25%. In addition, the light-emitting element 23 and the light-emitting element 27 using mCzFLP and FLP2A, which are organic compounds with a low refractive index, for the hole injection layer 111 show higher efficiency than the comparative light-emitting element 19 using DBT3P-II, which is a material with a high refractive index.

[0393] also, Fig.23 Shown at 25mA / cm 2 The emission spectra when the current density is made to flow through the light-emitting element 19, the light-emitting element 23 and the light-emitting element 27 are compared. Fig.23 It can be seen that the emission spectra of the comparative light-emitting element 19 , the light-emitting element 23 , and the light-emitting element 27 have a peak near 518 nm, and the peak is derived from the light emission of Ir(ppy) 3 which is a guest material contained in the light-emitting layer 130 .

[0394] In addition, Table 10 shows that 1000 cd / m 2 Element characteristics of the nearby comparative light-emitting elements 19 to 22 and light-emitting elements 23 to 30.

[0395] [Table 10]

[0396] From the above results, it can be seen that the comparative light-emitting elements 19 to 22 and the light-emitting elements 23 to 30 manufactured in this example have good driving voltage and light-emitting efficiency regardless of the structure of the hole injection layer 111.

[0397] <Relationship between Refractive Index and External Quantum Efficiency of Hole Injection Layer 111>

[0398] exist Fig.24 In the table, the relationship between the chromaticity x and the external quantum efficiency of the organic material used for each hole injection layer 111 is shown using the values ​​of each element shown in Table 10. Fig.24 In the figure, the values ​​of comparison light-emitting elements 19 to 22 are used as the curve data of “DBT3P-II”, the values ​​of light-emitting elements 23 to 26 are used as the curve data of “mCzFLP”, and the values ​​of light-emitting elements 27 to 30 are used as the curve data of “FLP2A”.

[0399] from Fig.19 It can be seen that the organic compounds used for the hole injection layer 111 have high refractive index in the order of DBT3P-II>mCzFLP>FLP2A. Fig.24 It can be seen that, similar to Example 1, the lower the refractive index of the organic compound used for the hole injection layer 111, the higher the external quantum efficiency. This is because the light attenuation caused by the evanescent mode is reduced, and the light extraction efficiency is improved.

[0400] This shows that, by using an organic compound having a low refractive index in the hole injection layer 111 , a light-emitting element having high light extraction efficiency can be obtained while maintaining hole injection characteristics. Example 3

[0401] In this example, a manufacturing example of a light-emitting element which is one of electronic devices of one embodiment of the present invention and characteristics of the light-emitting element are described. In addition, an organic compound used for a hole injection layer and a refractive index of the hole injection layer are described. Figure 2A 1 is a cross-sectional view showing the structure of the device manufactured in this example. In addition, Tables 11 to 14 show the detailed device structure. In addition, the structures and abbreviations of the compounds used can refer to the above-mentioned embodiment and examples.

[0402] [Table 11]

[0403] [Table 12]

[0404] [Table 13] Comparison of light emitting elements 31 Comparison of light emitting elements 32 Comparison of light emitting elements 33 Comparison of light emitting elements 34 <![CDATA[x3]]> 35 40 45 50

[0405] [Table 14]

[0406] <Measurement of refractive index> The refractive index of the organic compound used for the hole injection layer 111 of comparative light-emitting elements 31 to 34, 35 to 38, 39 to 42, 43 to 46, and 47 to 50 and the hole injection layer 111 used for comparative light-emitting elements 31 to 34, 35 to 38, 39 to 42, 43 to 46, and 47 to 50 was measured. The refractive index was measured in the same manner as in Example 1.

[0407] Fig.25 The results of measuring the refractive index of each film for light with a wavelength of 532 nm are shown. Fig.25 It can be seen that DBT3P-II used for comparative light-emitting elements 31 to 34 has the highest refractive index. CzC used for light-emitting elements 35 to 38, CzSi used for light-emitting elements 39 to 42, FATPA used for light-emitting elements 43 to 46, and 1,4-bis(triphenylsilyl)benzene (abbreviated as: UGH-2) used for comparative light-emitting elements 47 to 50 are organic compounds with very low refractive index, that is, n Ordinary is less than 1.70.

[0408] In addition, the hole injection layer 111 is required to have hole injecting properties, so it is preferable to include an electron donating material. The hole injection layer 111 of each light emitting element using MoO3 with a high refractive index as an electron donating material is estimated to have a high refractive index. Fig.25 It can be seen that the refractive index of the film formed by adding MoO3 of the hole injection layer 111 of each light-emitting element to each organic compound is slightly greater than the refractive index of each organic compound. That is, by using a material with a low refractive index and electron donating property as the hole injection layer 111, 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 material with electron donating property.

[0409] In addition, by Fig.25 It can be seen that the difference between n Ordinary and n Extraordinary of the hole injection layer 111 of each light emitting element is smaller than that of each organic compound film. That is, the mixed film of MoO3, an electron donating material, and an organic compound has lower anisotropy than the organic compound film.

[0410] In addition, the mixed film of CzSi and MoO3 of the organic compound used for the hole injection layer 111 of light-emitting elements 39 to 42 and the mixed film of UGH-2 and MoO3 of the organic compound used for the hole injection layer 111 of comparison light-emitting elements 47 to 50 have the same refractive index as the respective organic compounds, and the refractive index thereof is estimated to be lower than that of the mixed film of DBT3P-II and MoO3 of the hole injection layer 111 of comparison light-emitting elements 1 to 4.

[0411] <Manufacturing of Light Emitting Element> <<Manufacturing of Comparative Light-Emitting Elements 31 to 34>> As the electrode 101, a 70 nm thick ITSO film was formed on a glass substrate. In addition, the area of ​​the electrode 101 was 4 mm 2 (2mm×2mm).

[0412] Next, as a hole injection layer 111, 1,3,5-tri-(4-dibenzothienyl)-benzene (abbreviation: DBT3P-II) and MoO3 were co-evaporated on the electrode 101 in a weight ratio (DBT3P-II:MoO3) of 2:0.5 and a thickness of x3nm. Note that the value of x3 varies depending on each light-emitting element, and Table 13 shows the value of x3 in each light-emitting element.

[0413] Next, PCCP was deposited on the hole injection layer 111 to a thickness of 20 nm as the hole transport layer 112 .

[0414] Next, as the light-emitting layer 130(1), 4,6mCzP2Pm, PCCP, and Ir(ppy)3 were co-deposited on the hole transport layer 112 in a weight ratio (4,6mCzP2Pm:PCCP:Ir(ppy)3) of 0.5:0.5:0.1 and a thickness of 20 nm, and then as the light-emitting layer 130(2), they were co-deposited in a weight ratio (4,6mCzP2Pm:PCCP:Ir(ppy)3) of 0.8:0.2:0.1 and a thickness of 20 nm. Note that in the light-emitting layer 130(1) and the light-emitting layer 130(2), Ir(ppy)3 is a guest material that exhibits phosphorescence.

[0415] Next, 4,6mCzP2Pm was co-evaporated on the light-emitting layer 130(2) to a thickness of 20 nm as the first electron transport layer 118(1). Then, bathophenanthroline (abbreviated as BPhen) was evaporated on the first electron transport layer 118(1) to a thickness of 10 nm as the second electron transport layer 118(2).

[0416] Next, as the electron injection layer 119 , lithium fluoride (LiF) was deposited on the second electron transport layer 118 ( 2 ) to a thickness of 1 nm.

[0417] Next, aluminum (Al) was formed as the electrode 102 on the electron injection layer 119 to a thickness of 200 nm.

[0418] Next, in a glove box with a nitrogen atmosphere, a sealing glass substrate was fixed to a glass substrate on which an organic material was formed using an organic EL sealing agent to seal comparative light-emitting elements 31 to 34. Specifically, the sealing agent was applied around the organic material on the glass substrate on which an organic material was formed, and the substrate and the sealing glass substrate were bonded together at 6 J / cm 2 Ultraviolet light having a wavelength of 365 nm was irradiated, and a heat treatment was performed at 80° C. for 1 hour. Comparative light-emitting elements 31 to 34 were obtained through the above-described steps.

[0419] <<Manufacturing of Light-Emitting Elements 35 to 46 and Comparative Light-Emitting Elements 47 to 50>> The difference between the manufacturing process of light-emitting elements 35 to 46 and comparative light-emitting elements 47 to 50 and the comparative light-emitting elements 31 to 34 is the manufacturing process of the hole injection layer 111, and the other processes are the same as those of the comparative light-emitting elements 31 to 34. The detailed element structures are shown in Tables 11 to 14, and thus the detailed manufacturing method is omitted.

[0420] <Characteristics of Light Emitting Element> Next, the characteristics of the comparative light-emitting elements 31 to 34, the comparative light-emitting elements 35 to 46, and the comparative light-emitting elements 47 to 50 were measured. The measurement was performed in the same manner as in Example 1.

[0421] Fig.26 The current efficiency-luminance characteristics of the comparative light-emitting element 31, the light-emitting element 35, the light-emitting element 39, the light-emitting element 43, and the comparative light-emitting element 47 among the manufactured light-emitting elements are shown. In addition, Fig. 27 The current density-voltage characteristics are shown. Fig.28 The external quantum efficiency-brightness characteristics are shown. Note that Fig.28 The external quantum efficiency shown is the external quantum efficiency when measured from the front direction of the light-emitting element without viewing angle correction. In addition, as the organic compound of the hole injection layer 111, DBT3P-II is used for the comparative light-emitting element 31, CzC is used for the light-emitting element 35, CzSi is used for the light-emitting element 39, FATPA is used for the light-emitting element 43, and UGH-2 is used for the comparative light-emitting element 47, and the parts other than the hole injection layer 111 have the same element structure.

[0422] Depend on Fig.26 and Fig.28 It can be seen that the comparative light-emitting element 31, the light-emitting element 35, the light-emitting element 39, the light-emitting element 43, and the comparative light-emitting element 47 have a high current efficiency exceeding 90 cd / A and a high external quantum efficiency exceeding 25%. In addition, the light-emitting element 35, the light-emitting element 39, the light-emitting element 43, and the comparative light-emitting element 47 using an organic compound with a low refractive index for the hole injection layer 111 have higher efficiency than the comparative light-emitting element 31 using DBT3P-II, which is a material with a high refractive index. It can be seen that by using an organic compound with a low refractive index in the hole injection layer 111, the light attenuation caused by the evanescent wave can be suppressed.

[0423] In addition, by Fig. 27 It can be seen that the comparison light-emitting element 31, the light-emitting element 35, the light-emitting element 39 and the light-emitting element 43 have good current density-voltage characteristics to the same extent. On the other hand, the comparison light-emitting element 47 has a decrease in current density-voltage characteristics compared with the comparison light-emitting element 31, the light-emitting element 35, the light-emitting element 39 and the light-emitting element 43, and the hole injection property is low. This is because UGH-2 does not have an electron-donating group in the molecule. Therefore, when there is an electron-donating group in the molecule, even if a material with a small refractive index is used for the hole injection layer 111, a hole injection layer 111 with high hole injection properties can be manufactured.

[0424] also, Fig.29 Shown at 25mA / cm 2 The emission spectra when the current density is such that the current flows through the comparison light-emitting element 31, the light-emitting element 35, the light-emitting element 39, the light-emitting element 43, and the comparison light-emitting element 47. Fig.29 It can be seen that the emission spectra of comparison light-emitting element 31 , light-emitting element 35 , light-emitting element 39 , light-emitting element 43 and comparison light-emitting element 47 have a peak near 518 nm, and the peak originates from the light emission of Ir(ppy) 3 which is the guest material contained in light-emitting layer 130 .

[0425] In addition, Table 15 shows that 1000 cd / m 2 The device characteristics of the nearby comparative light-emitting elements 31 to 34, 35 to 46, and 47 to 50. The external quantum efficiency shown in Table 15 is the external quantum efficiency after viewing angle correction.

[0426] [Table 15]

[0427] From the above results, it can be seen that the comparative light-emitting elements 31 to 34, 35 to 46, and 47 to 50 manufactured in this embodiment have good driving voltage and luminous efficiency regardless of the structure of the hole injection layer 111.

[0428] <Reliability of Light Emitting Components> Next, a driving test was performed on the comparative light-emitting element 31 , the light-emitting element 35 , the light-emitting element 39 , the light-emitting element 43 , and the comparative light-emitting element 47 at a constant current of 2 mA. Fig.30 The results are shown in Figure 2. Fig.30 It can be seen that the reliability of the comparative light-emitting element 31, the light-emitting element 35, the light-emitting element 39, and the light-emitting element 43 is higher than that of the comparative light-emitting element 47. In particular, the light-emitting element 43 has high reliability. As described above, since the organic compound used for the hole injection layer 111 of the comparative light-emitting element 31, the light-emitting element 35, the light-emitting element 39, and the light-emitting element 43 has an electron-donating group in the molecule, it can be considered that it has a high hole injection property compared with UGH-2 used for the comparative light-emitting element 47. Therefore, the higher the hole injection property of the hole injection layer 111, the higher the reliability of the light-emitting element. Note that in Fig.30 In FIG. 1 , the reliability test results of the light emitting element 31 , the light emitting element 35 and the light emitting element 39 overlap with each other.

[0429] <Relationship between the Refractive Index of the Hole Injection Layer 111 and the External Quantum Efficiency>

[0430] exist Fig.31 In the table 15, the relationship between the chromaticity x and the external quantum efficiency of the organic material used for each hole injection layer 111 is shown using the values ​​of each element shown in Table 15. Fig.31 In the figure, the values ​​of comparison light-emitting elements 31 to 34 are used as curve data for “DBT3P-II”, the values ​​of light-emitting elements 35 to 38 are used as curve data for “CzC”, the values ​​of light-emitting elements 39 to 42 are used as curve data for “CzSi”, the values ​​of light-emitting elements 43 to 46 are used as curve data for “FATPA”, and the values ​​of comparison light-emitting elements 47 to 50 are used as curve data for “UGH-2”.

[0431] from Fig.25 It can be seen that DBT3P-II, an organic compound used for the hole injection layer 111, has a high refractive index exceeding 1.80, but CzC, CzSi, FATPA, and UGH-2 are organic compounds having a low refractive index of 1.70 or less. Fig.31It is found that the light-emitting element using an organic compound with a low refractive index for the hole injection layer 111 has a higher external quantum efficiency than the light-emitting element using DBT3P-II for the hole injection layer 111. This is because the light attenuation caused by the evanescent mode is reduced and the light extraction efficiency is improved.

[0432] This shows that by using either a tetraarylmethane skeleton or a tetraarylsilane skeleton and an organic compound having an electron donating group in the hole injection layer 111 , a light-emitting element with high light extraction efficiency and reliability can be obtained while maintaining hole injection characteristics. Example 4

[0433] In this example, a manufacturing example of a light-emitting element which is one of electronic devices of one embodiment of the present invention and characteristics of the light-emitting element are described. In addition, an organic compound used for a hole injection layer and a refractive index of the hole injection layer are described. Figure 2A A cross-sectional view of the element structure manufactured in this embodiment is shown. In addition, Table 16 and Table 17 show the detailed element structure. The structures and abbreviations of the compounds used are shown below. Note that for other organic compounds, reference can be made to the above embodiments and implementation methods. Note that in the light-emitting element shown in this embodiment, no metal oxide is used as the hole injection layer 111, and the hole injection layer 111 is composed only of an organic compound.

[0434] [Chemical formula 10]

[0435] [Table 16]

[0436] [Table 17]

[0437] <Measurement of refractive index> 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 refractive index was measured in the same manner as in Example 1. Table 18 shows the values ​​of the refractive index (nOrdinary) of each film for light with a wavelength of 633 nm.

[0438] [Table 18] Hole injection layer 111 (weight ratio) ordinary β-TNB:p-dopant(1:0.01) 1.77 NPB: p-dopant (1:0.01) 1.77 BPAFLP:p-dopant(1:0.01) 1.73 TAPC: p-dopant (1:0.01) 1.67

[0439] As can be seen from Table 18, the mixed film of N,N,N',N'-tetra-naphth-2-yl-benzidine (abbreviation: β-TNB) and p-dopant (material purchased from Analysis Kobo Co., Ltd.) used in Comparative Light-Emitting Elements 51 to 54 and the mixed film of NPB and p-dopant used in Comparative Light-Emitting Elements 55 to 58 have a high refractive index greater than 1.75. On the other hand, the mixed film of BPAFLP and p-dopant used in Light-Emitting Elements 59 to 62 and the mixed film of TAPC and p-dopant used in Light-Emitting Elements 63 to 66 have a low refractive index of less than 1.75.

[0440] <Manufacturing of Light Emitting Element> »Manufacturing of Comparative Light-Emitting Elements 51 to 54 » As the electrode 101, a 70 nm thick ITSO film was formed on a glass substrate. In addition, the area of ​​the electrode 101 was 4 mm 2 (2mm×2mm).

[0441] Next, as the hole injection layer 111 , co-evaporation was performed on the electrode 101 so that the weight ratio of β-TNB to p-dopant (β-TNB:p-dopant) was 1:0.01 and the thickness was 60 nm.

[0442] Next, PCBBiF was deposited on the hole injection layer 111 to a thickness of z1 nm as the hole transport layer 112. Note that the value of z1 varies depending on each light-emitting element, and Table 17 shows the value of z1 in each light-emitting element.

[0443] Next, as the light-emitting layer 130(1), 2mDBTBPDBq-II, PCBBiF, and Ir(dppm)2(acac) were co-deposited on the hole transport layer 112 in a weight ratio of 0.7:0.3:0.06 (2mDBTBPDBq-II:PCBBiF:Ir(dppm)2(acac)) to form a thickness of 20 nm, and then, as the light-emitting layer 130(2), 2mDBTBPDBq-II:PCBBiF:Ir(dppm)2(acac) were co-deposited in a weight ratio of 0.8:0.2:0.06 (2mDBTBPDBq-II:PCBBiF:Ir(dppm)2(acac)) to form a thickness of 20 nm. Note that in the light-emitting layer 130(1) and the light-emitting layer 130(2), Ir(dppm)2(acac) is a guest material that exhibits phosphorescence.

[0444] Next, 2mDBTBPDBq-II was co-evaporated to a thickness of 20 nm on the light-emitting layer 130 (2) as the first electron transport layer 118 (1). Then, 2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as: NBPhen) was evaporated to a thickness of 20 nm on the first electron transport layer 118 (1) as the second electron transport layer 118 (2).

[0445] Next, as the electron injection layer 119 , lithium fluoride (LiF) was deposited on the second electron transport layer 118 ( 2 ) to a thickness of 1 nm.

[0446] Next, aluminum (Al) was formed as the electrode 102 on the electron injection layer 119 to a thickness of 200 nm.

[0447] Next, in a glove box with a nitrogen atmosphere, a sealing glass substrate was fixed to a glass substrate on which an organic material was formed using an organic EL sealing agent to seal comparative light-emitting elements 51 to 54. Specifically, the sealing agent was applied around the organic material on the glass substrate on which an organic material was formed, and the substrate and the sealing glass substrate were bonded together, and the sealing agent was applied at 6 J / cm 2 Ultraviolet light having a wavelength of 365 nm was irradiated, and a heat treatment was performed at 80° C. for 1 hour. Comparative light-emitting elements 51 to 54 were obtained through the above-described steps.

[0448] 》Manufacturing of Comparative Light-Emitting Elements 55 to 58 and Light-Emitting Elements 59 to 66》 The manufacturing process of comparative light-emitting elements 55 to 58 and light-emitting elements 59 to 66 is different from that of comparative light-emitting elements 51 to 54 only in the manufacturing process of the hole injection layer 111, and the other processes are the same as those of comparative light-emitting elements 51 to 54. The detailed element structures are shown in Tables 16 and 17, and thus the detailed manufacturing method is omitted.

[0449] <Characteristics of Light Emitting Element> Next, the characteristics of the comparative light-emitting elements 51 to 58 and the light-emitting elements 59 to 66 were measured. The measurement was performed in the same manner as in Example 1. Table 19 shows the characteristics of the comparative light-emitting elements 51 to 58 and the light-emitting elements 59 to 66. 2 The external quantum efficiency shown in Table 19 is the external quantum efficiency before viewing angle correction.

[0450] [Table 19]

[0451] From the above results, it can be seen that the comparative light-emitting elements 51 to 58 and the light-emitting elements 59 to 66 manufactured in this example have good driving voltage and light-emitting efficiency regardless of the structure of the hole injection layer 111.

[0452] <Relationship between the Refractive Index of the Hole Injection Layer 111 and the External Quantum Efficiency> exist Fig.32 In the table, the relationship between the chromaticity y and the external quantum efficiency of the organic material used for each hole injection layer 111 is shown using the values ​​of each element shown in Table 19. Fig.32 , the values ​​of comparison light-emitting elements 51 to 54 are used as curve data for “β-TNB”, the values ​​of comparison light-emitting elements 55 to 58 are used as curve data for “NPB”, the values ​​of light-emitting elements 59 to 62 are used as curve data for “BPAFLP”, and the values ​​of light-emitting elements 63 to 66 are used as curve data for “TAPC”.

[0453] As can be seen from Table 18, when β-TNB and NPB are used for the hole injection layer 111, the hole injection layer 111 has a high refractive index exceeding 1.75, but when BPAFLP and TAPC are used for the hole injection layer 111, the hole injection layer 111 has a low refractive index of less than 1.75. Fig.32 It can be seen that, for example, when comparing the external quantum efficiencies of the light-emitting elements around the y chromaticity of 0.435, the light-emitting element including the hole injection layer 111 having a low refractive index has a higher external quantum efficiency. Therefore, in the case of having the same chromaticity, the light-emitting element including the hole injection layer 111 having a low refractive index has a higher luminous efficiency. This is because the light attenuation caused by the evanescent mode is reduced, and the light extraction efficiency is improved.

[0454] (Reference Example 1) In this reference example, the synthesis method of Ir(pbi-diBuCNp) 3 used in Example 1 is described.

[0455] <Step 1: Synthesis of 4-amino-3,5-diisobutylbenzonitrile> 52 g (280 mmol) of 4-amino-3,5-dichlorobenzonitrile, 125 g (1226 mmol) of isobutylboric 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, the flask was purged with nitrogen, and the mixture was degassed while being stirred while reducing the pressure in the flask. After degassing, 4.8 g (5.2 mmol) of tris(dibenzylideneacetone)dipalladium (0) was added, and the mixture was stirred at 130° C. for 12 hours under a nitrogen stream. Toluene is added to the obtained reaction solution, and suction filtration is performed through a filter aid composed of diatomaceous earth (Wako Pure Chemical Industries, Ltd., catalog number: 531-16855) / magnesium silicate (Wako Pure Chemical Industries, Ltd., catalog number: 540-00135) / alumina layered in this order. The obtained filtrate is concentrated to obtain an oily substance. The obtained oily substance is purified by silica gel column chromatography. Toluene is used as a developing solvent. The obtained fraction is concentrated to obtain 61 g of a 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 following formula (a-1) shows the synthesis scheme of step 1.

[0456] [Chemical formula 11]

[0457] <Step 2: Synthesis of 4-[N-(2-nitrophenyl)amino]-3,5-diisobutylbenzonitrile> 30 g (131 mmol) of 4-amino-3,5-diisobutylbenzonitrile synthesized by 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 a specified time, the reaction solution was extracted with chloroform to obtain a crude product. The obtained crude product was purified by silica gel column chromatography. As a developing solvent, hexane: ethyl acetate = 7:1 was used. The obtained fraction was concentrated to obtain an orange solid. Hexane was added to the obtained solid and filtered to obtain 16 g of a yellow solid with a yield of 35%. Nuclear magnetic resonance (NMR) confirmed that the obtained yellow solid was 4-[N-(2-nitrophenyl)amino]-3,5-diisobutylbenzonitrile. The synthesis scheme of step 2 is shown in the following formula (a-2).

[0458] [Chemical formula 12]

[0459] <Step 3; Synthesis of 4-[N-(2-aminophenyl)amino]-3,5-diisobutylbenzonitrile> 21g (60.0mmol) of 4-[N-(2-nitrophenyl)amino]-3,5-diisobutylbenzonitrile synthesized by step 2, 11mL (0.6mol) of water and 780mL of ethanol were placed in a 2000mL three-necked flask and stirred. 57g (0.3mol) of tin (II) chloride was added to the mixture and stirred at 80°C for 7.5 hours under a nitrogen stream. After the specified time, the mixture was poured into 400mL of 2M sodium hydroxide aqueous solution and stirred at room temperature for 16 hours. The precipitated precipitate was removed by suction filtration and washed with chloroform to obtain a filtrate. The obtained filtrate was extracted with chloroform. Then, the extracted solution was concentrated to obtain 20g of a white solid with a yield of 100%. Nuclear magnetic resonance (NMR) confirmed that the obtained white solid was 4-[N-(2-aminophenyl)amino]-3,5-diisobutylbenzonitrile. The following formula (a-3) shows the synthesis scheme of step 3.

[0460] [Chemical formula 13]

[0461] <Step 4: Synthesis of 1-(4-cyano-2,6-diisobutylphenyl)-2-phenyl-1H-benzimidazole (abbreviated as: Hpbi-diBuCNp)> 20 g (60.0 mmol) of 4-[N-(2-aminophenyl)amino]-3,5-diisobutylbenzonitrile synthesized by step 3, 200 mL of acetonitrile and 6.4 g (60.0 mmol) of benzaldehyde were placed in a 1000 mL eggplant flask and stirred at 100°C for 1 hour. 100 mg (0.60 mmol) of iron (III) chloride was added to the mixture and stirred at 100°C for 24 hours. After the specified time, the reaction solution was extracted with chloroform to obtain an oily substance. Toluene was added to the obtained oily substance, and suction was performed through a filter aid layered with diatomaceous earth / magnesium silicate / alumina. The obtained filtrate was concentrated to obtain an oily substance. The obtained oily substance was purified by silica gel column chromatography. Toluene was used as a developing solvent. The obtained fraction was concentrated to obtain a solid. The solid was recrystallized using ethyl acetate / hexane to obtain 4.3 g of the target white solid in a yield of 18%. The obtained white solid was confirmed to be 1- (4-cyano-2,6-diisobutylphenyl)-2-phenyl-1H-benzimidazole (abbreviation: Hpbi-diBuCNp). The synthesis scheme of step 4 is shown in the following formula (a-4).

[0462] [Chemical formula 14]

[0463] <Step 5; tri{2-[1-(4-cyano-2,6-diisobutylphenyl)-1H-benzimidazol-2-yl-κN 3 Synthesis of phenyl-κC}iridium(III) (abbreviated as: Ir(pbi-diBuCNp)3)> 1.8 g (4.4 mmol) of 1-(4-cyano-2,6-diisobutylphenyl)-2-phenyl-1H-benzimidazole (abbreviated as: Hpbi-diBuCNp) synthesized by step 4 and 0.43 g (0.88 mmol) of tris(acetylacetone)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 resulting solid was purified by silica gel column chromatography (using neutral silica gel). Toluene was used as a developing solvent. The resulting fraction was concentrated to obtain a solid. The resulting solid was recrystallized using ethyl acetate / hexane to obtain 0.26 g of a yellow solid in a yield of 21%. The following formula (a-5) shows the synthesis scheme.

[0464] [Chemical formula 15]

[0465] The protons of the yellow solid obtained by the above steps ( 1 H) was measured. From the measurement results, it can be seen that Ir(pbi-diBuCNp)3 (a mixture of fac-isomers and mer-isomers) was obtained in this reference example. 1 H-NMR confirmed an isomer mixture of fac-isomer and merid-isomer. The isomer ratio was fac-isomer:merid-isomer=3:2. [Explanation of symbols]

[0466] 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: light-emitting unit, 108: light-emitting unit, 110: light-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: light-emitting layer, 121: guest material, 122: host material, 130: light-emitting layer, 131: guest material, 131_1: organic compound, 131_2: organic compound, 132: host material, 134: light-emitting region, 140: light-emitting layer, 141: guest material, 142: host material, 142_1: organic compound, 142_2: organic compound, 150: light-emitting element, 170: light-emitting layer, 200: substrate, 250: light-emitting element, 252: light-emitting element, 601: source side driver circuit, 602: pixel portion, 603: gate side driver circuit, 604: sealing substrate, 605: sealing agent, 607: space, 608: wiring, 610: element substrate, 611: switching TFT, 612: current control TFT, 613: electrode, 614: insulator, 616: EL layer, 6 17: electrode, 618: light emitting element, 623: n-channel TFT, 624: p-channel TFT, 900: portable information terminal, 901: housing, 902: housing, 903: display unit, 905: hinge unit, 910: portable information terminal, 911: housing, 912: display unit, 913: operation button, 914: external connection port, 915: speaker, 916: microphone, 917: camera, 920: camera, 921: housing, 922: display unit, 923: operation button, 924: shutter button, 926: lens, 1001: substrate, 1002: base insulating film, 1003: gate insulating film, 1006: gate electrode, 1007: gate electrode, 10 08: gate electrode, 1020: interlayer insulating film, 1021: interlayer insulating film, 1022: electrode, 1024B: electrode, 1024G: electrode, 1024R: electrode, 1024W: electrode, 1025B: lower electrode, 1025G: lower electrode, 1025R: lower electrode, 1025W: lower electrode, 1026: partition wall, 1028: EL layer, 1029: electrode, 1031: sealing substrate, 1032: sealant, 1033: base material, 1034B: coloring layer, 1034G: coloring layer, 1034R: coloring layer, 1036: protective layer, 1037: interlayer insulating film, 1040: pixel portion, 1041: driver circuit portion, 1042: peripheral portion,3054: display unit, 3500: multi-function 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

1. An electronic device comprising: The first layer, the second layer and the third layer between the first electrode and the second electrode, wherein the first layer is disposed between the first electrode and the second layer, The second layer is disposed between the first layer and the third layer, The first layer includes a first substance and a first organic compound, The first substance has electron accepting property, The third layer has the function of emitting or absorbing light, The refractive index of the first layer is lower than the refractive index of the second layer, The refractive index of the second layer is lower than the refractive index of the third layer, When the first organic compound is a thin film, the refractive index for light having a wavelength of 532 nm is greater than 1 and less than 1.

75. The first organic compound has an electron donating property, Furthermore, the first organic compound includes non-mutual hydrocarbons. The electronic device according to claim 1 , wherein the third layer is in contact with the second layer. The electronic device according to claim 1 , wherein the first layer is in contact with the second layer.

4. An electronic device comprising: The first layer and the third layer between the first electrode and the second electrode, Wherein, the first layer is arranged between the first electrode and the third layer, The first layer is in contact with the first electrode, The first layer includes a first substance and a first organic compound, The first substance has electron accepting property, The third layer has the function of emitting or absorbing light, The first organic compound has an electron donating property, Furthermore, a difference between the refractive index of ordinary light and the refractive index of extraordinary light of the film including the first substance and the first organic compound is smaller than a difference between the refractive index of ordinary light and the refractive index of extraordinary light of the film including the first organic compound.

5. An electronic device comprising: The first layer and the third layer between the first electrode and the second electrode, Wherein, the first layer is arranged between the first electrode and the third layer, The first layer is in contact with the first electrode, The first layer includes a first substance and a first organic compound, The first substance has electron accepting property, The third layer has the function of emitting or absorbing light, The first organic compound has an electron donating property, The refractive index of the ordinary light of the film including the first organic compound is higher than the refractive index of the extraordinary light of the film including the first organic compound, Furthermore, the refractive index of ordinary light of the film including the first substance and the first organic compound is smaller than the refractive index of extraordinary light of the film including the first substance and the first organic compound. 6 . The electronic device according to claim 1 , wherein a volume ratio of the first substance relative to the first organic compound is 0.01 or more and 0.3 or less.

7. The electronic device according to any one of claims 1, 4 and 5, wherein the first substance 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.

8. The electronic device according to any one of claims 1, 4 and 5, wherein the first substance is any one of TCNQ, F4TCNQ and F6TCNNQ.

9. A display device, comprising: The electronic device according to any one of claims 1, 4 and 5; as well as At least one of a color filter and a transistor.

10. An electronic device comprising: The display device according to claim 9; as well as At least one of the housing and the touch sensor.

11. A lighting device, comprising: The electronic device according to any one of claims 1, 4 and 5; as well as At least one of the housing and the touch sensor.

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