Light-emitting device

Abstract

To provide a light-emitting element including a plurality of light-emitting layers between a pair of electrodes, in each light-emitting layer of which the driving voltage is low and the luminous efficiency is high.SOLUTION: A light-emitting element includes a first light-emitting layer to a third light-emitting layer between a cathode and an anode. The first light-emitting layer includes a first phosphorescent material and a first electron-transporting material. The second light-emitting layer includes a second phosphorescent material and a second electron-transporting material. The third light-emitting layer includes a fluorescent material and a third electron-transporting material. The first light-emitting layer to the third light-emitting layer are provided in contact with an electron-transporting layer provided on a cathode side. The triplet excitation energy level of the material that forms the electron-transporting layer is lower than the triplet excitation energy level of the first electron-transporting material and the second electron-transporting material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention is a light-emitting layer that emits light when an electric field is applied between a pair of electrodes. A light-emitting element comprising the same, a light-emitting device, an electronic device, and a lighting device each having such a light-emitting element are also provided. Regarding placement. [Background technology]

[0002] The organic compound used as the light-emitting layer has the characteristics of being thin, lightweight, fast response, and driven by low DC voltage. The light-emitting element used is expected to be applied to next-generation flat panel displays. In addition, a display device with light-emitting elements arranged in a matrix has a higher visual quality than a conventional liquid crystal display device. It is believed that its advantages lie in its wide field of view and excellent visibility.

[0003] The light-emitting mechanism of a light-emitting element is to sandwich a light-emitting layer containing a light-emitting body between a pair of electrodes and apply a voltage. As a result, electrons injected from the cathode and holes injected from the anode are emitted at the luminescence center of the luminescent layer. recombines to form molecular excitons, which then release energy as they relax to the ground state. It is said that the excited state is a singlet excited state and a triplet excited state. It is believed that light emission can occur through either excited state, and the singlet excited state (S * ) is emitted from the triplet excited state (T * ) is called phosphorescence.

[0004] Regarding such light-emitting devices, in order to improve the device characteristics or productivity, Improvements and material development are being actively carried out. In addition, research on organic EL elements is also underway. Development is being carried out vigorously, and efforts to make it full color are gaining momentum.

[0005] One method for achieving full color is to paint the light-emitting layer separately for each pixel. The light-emitting layer is deposited only on the required pixels using a shadow mask. In order to reduce the number of layers and reduce costs, layers other than the light-emitting layer, such as a hole transport layer, an electron transport layer, A configuration has been disclosed in which a cathode is formed in common for a plurality of pixels (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-6362 Summary of the Invention [Problem to be solved by the invention]

[0007] In the configuration described in Patent Document 1, the hole transport layer or the electron transport layer is shared by a plurality of pixels. Since the pixels are used interchangeably, the device characteristics, such as the driving voltage, differ for each pixel that displays a different color. In addition, in such a configuration, the hole transport layer or the electron transport layer is used for pixels that display different colors. Since the transmission layer is common, the element configuration is not optimal for each pixel, and at least In any one pixel, abnormality in the element characteristics, such as an increase in driving voltage or a decrease in reliability, There are issues such as the following occurring.

[0008] In view of the above-described problems, one embodiment of the present invention provides a light-emitting device having a plurality of light-emitting layers between a pair of electrodes. The device has a plurality of light-emitting layers each of which has a low driving voltage and a high luminous efficiency. One of the objects is to provide an optical element. [Means for solving the problem]

[0009] One embodiment of the present invention is a light-emitting element including first to third light-emitting layers between a cathode and an anode. the first light-emitting layer comprises a first phosphorescent material and a first electron-transporting material; The second light-emitting layer includes a second phosphorescent material and a second electron-transporting material, and the third light-emitting layer includes a second phosphorescent material and a second electron-transporting material. The first light-emitting layer, the second light-emitting layer, the third light-emitting layer, and the third light-emitting layer include a fluorescent material and a third electron-transporting material. , which are provided in contact with the electron transport layer arranged on the cathode side, and are materials for forming the electron transport layer. The triplet excited energy level of the first electron transporting material and the second electron transporting material is The light-emitting element is characterized in that the excitation energy level is lower than the first excitation energy level.

[0010] In this way, by using a structure in which the electron transport layer is in contact with the first to third light-emitting layers in common, The productivity in forming optical elements can be improved. The triplet excited energy level (T1 level) of the material and the second electron transport material is higher than the T1 level. The electron transport of the first electron transport material and the second electron transport material is low. Because of its high transmittance, the light-emitting region of the light-emitting element of one embodiment of the present invention is formed on the hole-transport layer side of the light-emitting layer. Therefore, the first and second light-emitting layers are affected by the low T1 level of the electron transport layer. This results in a device configuration that is not affected by the influence of the external force, has a low driving voltage, and has high luminous efficiency.

[0011] Another embodiment of the present invention is a light-emitting device including first to third light-emitting layers between a cathode and an anode. a first light-emitting layer including a first phosphorescent material and a first electron-transporting material; the second light-emitting layer comprises a second phosphorescent material and a second electron-transporting material; and The light-emitting layer includes a fluorescent material and a third electron-transporting material, and the first light-emitting layer and the second light-emitting layer include a a third electron transport material provided in contact with the cathode side of the light emitting layer, the triplet excited energy level of which is , lower than the triplet excitation energy levels of the first electron transporting material and the second electron transporting material. The light-emitting element is characterized by the above.

[0012] In this way, the third light-emitting layer is provided in contact with the cathode sides of the first light-emitting layer and the second light-emitting layer. Thus, the third light-emitting layer functions as an electron transport layer on the first light-emitting layer and the second light-emitting layer. In the third light-emitting layer, it functions as a light-emitting layer. The fluorescent material (also called a dopant or guest material) contained in the first electron transport material Since the electron transporting property of the second electron transporting material is high, the first light-emitting layer and the second light-emitting layer On the other hand, in the third light-emitting layer, light is emitted from the fluorescent material. That is, since the third light-emitting layer simultaneously functions as an electron transport layer and a light-emitting layer, The first and second light-emitting layers can be commonly used as an electron transport layer. Therefore, the third light-emitting layer can be used as a light-emitting layer. This can increase productivity during element formation.

[0013] Another embodiment of the present invention is a light-emitting device having a light-emitting element, an electronic device having the light-emitting device, and Therefore, the light-emitting device in this specification includes: This refers to an image display device or a light source (including lighting equipment). Also, a light-emitting device with a connector , such as FPC (Flexible printed circuit) or TCP (Tape Carrier Package) mounted module, TCP A module with a printed wiring board or a light emitting element with COG (Chip On Glass) All modules with ICs (integrated circuits) directly mounted using the Glass method are light-emitting devices. This shall be included in the [Effects of the Invention]

[0014] A light-emitting element which is one embodiment of the present invention is a light-emitting element which has a plurality of light-emitting layers between a pair of electrodes. Thus, in each of the plurality of light-emitting layers, a light-emitting element having a low driving voltage and high light-emitting efficiency is formed. Furthermore, it is possible to improve productivity when forming the light emitting element. can. [Brief explanation of the drawings]

[0015] [Figure 1] 1A to 1C illustrate a light-emitting element of one embodiment of the present invention. [Figure 2] 1A to 1C illustrate a light-emitting element of one embodiment of the present invention. [Figure 3] 1A to 1C illustrate a light-emitting element of one embodiment of the present invention. [Figure 4] 1A and 1B illustrate a light-emitting device using a light-emitting element of one embodiment of the present invention. [Figure 5] 1A to 1C illustrate electronic devices each including a light-emitting element and a light-emitting device according to one embodiment of the present invention. [Figure 6] 1A to 1C are diagrams illustrating light-emitting elements according to an embodiment. [Figure 7] FIG. 10 shows current density-luminance characteristics of Light-emitting Element 1 and Comparative Light-emitting Element 2. [Figure 8] FIG. 10 shows voltage-luminance characteristics of the light-emitting element 1 and the comparative light-emitting element 2. [Figure 9] FIG. 10 shows luminance-current efficiency characteristics of the light-emitting element 1 and the comparative light-emitting element 2. [Figure 10] FIG. 10 shows voltage-current characteristics of the light-emitting element 1 and the comparative light-emitting element 2. [Figure 11] 10 shows emission spectra of the light-emitting element 1 and the comparative light-emitting element 2. FIG. [Figure 12] FIG. 10 shows current density-luminance characteristics of the light-emitting element 3 and the comparative light-emitting element 4. [Figure 13] FIG. 10 shows voltage-luminance characteristics of the light-emitting element 3 and the comparative light-emitting element 4. [Figure 14] FIG. 10 shows luminance-current efficiency characteristics of the light-emitting element 3 and the comparative light-emitting element 4. [Figure 15] 10 shows voltage-current characteristics of the light-emitting element 3 and the comparative light-emitting element 4. [Figure 16] 10 shows emission spectra of the light-emitting element 3 and the comparative light-emitting element 4. FIG. [Figure 17] FIG. 10 shows current density-luminance characteristics of the light-emitting element 5 and the comparative light-emitting element 6. [Figure 18] FIG. 10 shows voltage-luminance characteristics of the light-emitting element 5 and the comparative light-emitting element 6. [Figure 19] FIG. 10 shows luminance-current efficiency characteristics of the light-emitting element 5 and the comparative light-emitting element 6. [Figure 20] FIG. 10 shows voltage-current characteristics of the light-emitting element 5 and the comparative light-emitting element 6. [Figure 21] FIG. 10 shows emission spectra of the light-emitting element 5 and the comparative light-emitting element 6. [Figure 22] 10 is a graph showing current density-luminance characteristics of the light-emitting elements 7 and 8. FIG. [Figure 23] 10 is a graph showing voltage-luminance characteristics of the light-emitting elements 7 and 8. FIG. [Figure 24] 10 shows luminance-current efficiency characteristics of the light-emitting elements 7 and 8. FIG. [Figure 25] 10 is a graph showing voltage-current characteristics of the light-emitting elements 7 and 8. FIG. [Figure 26] 10 shows emission spectra of the light-emitting elements 7 and 8. FIG. [Figure 27] 10 shows the results of reliability tests on light-emitting elements 1, 3, 7, and 8 and comparative light-emitting elements 2 and 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the embodiments and details thereof may be modified without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the embodiments described below. It is not to be construed as being limited to the content.

[0017] In addition, the position, size, range, etc. of each component shown in the drawings etc. are not necessarily shown in order to facilitate understanding. It may not represent the actual position, size, range, etc. Therefore, the disclosed invention The position, size, range, etc. are not necessarily limited to those disclosed in the drawings, etc.

[0018] In this specification, ordinal numbers such as "first," "second," and "third" refer to the order of components. It should be noted that this is added to avoid confusion and is not intended to limit the number.

[0019] (Embodiment 1) In this embodiment, a concept and specific examples of forming a light-emitting element according to one embodiment of the present invention will be described. First, a light-emitting element according to one embodiment of the present invention will be described with reference to FIG. This will be explained using 1(A) and (B).

[0020] The light-emitting element shown in FIG. 1(A) has a light-emitting layer 1 between a pair of electrodes (anode 101 and cathode 103). 15, and the light-emitting layer 115 comprises a first phosphorescent material 121a and a first electron-transporting material 122. a first light-emitting layer 115a containing a second phosphorescent material 131a and a second electron-transporting material 131b; a second light-emitting layer 115b containing a fluorescent material 141a and a third electron-transporting material 14 and a third light-emitting layer 115c including 2a.

[0021] In addition, each of the first light-emitting layer 115a, the second light-emitting layer 115b, and the third light-emitting layer 115c This is provided in contact with the electron transport layer 117 arranged on the cathode 103 side.

[0022] The first light-emitting layer 115a is made of a first phosphorescent material 121a and a first electron transport material The second hole transport material 122a may further include a first hole transport material 123a. The light-emitting layer 115b includes a second phosphorescent material 131a, a second electron-transporting material 132a, and The second hole transporting material 133a may also be included.

[0023] In the first light-emitting layer 115a, the first electron-transporting material 122a acts as a host material. The first phosphorescent material 121a functions as a guest material (also called a dopant). The first hole transport material 123a also functions as an assist material. The first electron transporting material 122a functions as a host material, and the first phosphorescent material 121a and The second light-emitting layer 115b has a structure in which the first hole transport material 123a and the second hole transport material 123b are dispersed. In the above, the second electron transporting material 132a functions as a host material, and the second phosphorescent material The second hole transporting material 131a functions as a guest material. That is, the second electron transporting material functions as a host material. The second phosphorescent material 131a and the second hole transport material 133a are dispersed in the second phosphorescent material 132a. In the third light-emitting layer 115c, the third electron transporting material 142a is The fluorescent material 141a functions as a base material, and the fluorescent material 141b functions as a guest material. The fluorescent material 141a is dispersed in the third electron transporting material 142a which functions as a host material. It is a structure that

[0024] For example, the first phosphorescent material 121a may be a phosphorescent material that emits red light. The second phosphorescent material 131a can be a material that emits green light. A phosphorescent material can be used as the light-emitting material. In this specification, a fluorescent material that emits blue light can be used as the light-emitting substance. In this case, the maximum emission wavelength of the phosphorescent material exhibiting red emission is greater than 570 nm and less than 740 nm. nm or less, and the maximum emission wavelength of the phosphorescent material exhibiting green emission is greater than 500 nm. The maximum emission wavelength of blue fluorescent materials is 570 nm or less, and the maximum emission wavelength of blue fluorescent materials is 400 nm or more. It is less than 500 nm.

[0025] In FIG. 1A, a light-emitting layer 115 and an electron transport layer 117 are provided between a pair of electrodes. In addition, a hole injection layer 111, a first hole transport layer 113a, a second hole transport layer 113b, a third hole transport layer 113c, a fourth hole transport layer 113d, a fifth hole transport layer 113e, a sixth hole transport layer 113f, a sixth hole transport layer 113g, a sixth hole transport layer 113h, a sixth hole transport layer 113i, a sixth hole transport layer 113j, a sixth hole transport layer The third hole transport layer 113c and the third electron injection layer 119 are formed on the insulating layer 113.

[0026] More specifically, the light-emitting device shown in FIG. 1A includes an anode 101 on a substrate 100, and a a hole injection layer 111 on the hole injection layer 111; a first hole transport layer 113a on the hole injection layer 111; a second hole transport layer 113b on the injection layer 111 and a third hole transport layer 113b on the hole injection layer 111; 113c, a first light-emitting layer 115a on the first hole transport layer 113a, and a second hole transport layer the second light-emitting layer 115b on the third hole transport layer 113b, and the third light-emitting layer 11 on the third hole transport layer 113c. 5c, and the first light-emitting layer 115a, the second light-emitting layer 115b, and the third light-emitting layer 115c. An electron transport layer 117, an electron injection layer 119 on the electron transport layer 117, and a and a cathode 103.

[0027] In this way, if necessary, a layer other than the light-emitting layer 115 and the electron transport layer 117 may be provided between the pair of electrodes. For example, a hole-injecting or electron-injecting substance, a hole-transporting or electron-transporting substance or a layer containing a bipolar substance (a substance having high electron transporting and hole transporting properties) or the like is formed. However, these are not necessarily required.

[0028] In addition, in the light-emitting element shown in FIG. 1A, the first hole-transporting layer 113a and the second hole-transporting layer 113b are The hole transport layer 113b and the third hole transport layer 113c are connected to each light-emitting layer (first light-emitting layer 115a , the second light-emitting layer 115b, and the third light-emitting layer 115c) are disposed on the However, the present invention is not limited to this configuration, and the hole transport layer may be formed in common for each light-emitting layer. In addition, in the light-emitting element shown in FIG. 1(A), the first hole-transporting layer 113a and the second By adjusting the film thickness of the hole transport layer 113b and the third hole transport layer 113c, The optical path of the light emitted from the light-emitting layer can be adjusted.

[0029] In the light-emitting element shown in FIG. 1A, the light-emitting layer 115 (first light-emitting layer 115a, The second light-emitting layer 115b and the third light-emitting layer 115c are formed by an electron transport layer 117, an electron injection layer The electron transport layer 117, the electron injection layer 119, and the cathode 103 are common to each other. 9 and the cathode 103 are commonly used in the light-emitting layer 115, The separate coating process shown in FIG. 1(A) can be performed in the first step of forming the light-emitting element. The first hole transport layer 113a, the second hole transport layer 113b, and the third hole transport layer 113c are A first light-emitting layer 115a, a second light-emitting layer 115b and a third light-emitting layer 115c are formed on the hole injection layer 111. The light-emitting layer 115c is formed by the first hole transport layer 113a, the second hole transport layer 113b, and the The hole transport layer 113c is formed on the hole transport layer 113c of the third layer. In addition, each hole transport layer and each light emitting layer are formed continuously. By doing so, it is possible to reduce the number of times of separate coating. For example, 3a and the first light-emitting layer 115a are formed successively, and the second hole transport layer 113b and the second light-emitting layer The third hole transport layer 113c and the third light emitting layer 115c are formed continuously. Therefore, the light-emitting element shown in FIG. 1(A) is formed by applying the coating three times in total. It is possible.

[0030] In addition, the light-emitting element shown in FIG. 1A includes a first electron-transporting material 122a and a second electron-transporting material 122b. The electron transporting property of the light-emitting material 132a is very high. The light-emitting region of the second light-emitting layer 115b is formed by the first hole transport layer 113a and the second hole transport layer 11 Therefore, the first light-emitting layer 115a and the second light-emitting layer 115b are formed in the region near the first light-emitting layer 115a and the second light-emitting layer 115b. The light emitted from b is emitted when the triplet excited energy level of the electron transport layer 117 is higher than that of the first electron transport material Although the triplet excitation energy is lower than that of the second electron transporting material 122a and the second electron transporting material 132a, However, the triplet excitation energy level of the electron transport layer 117 is not affected or is extremely low. and is less susceptible to impact.

[0031] That is, in the light-emitting element of one embodiment of the present invention, the first light-emitting layer 115a and the second light-emitting layer 11 In the case where a common electron transport layer 117 is used in the third light-emitting layer 115b and the third light-emitting layer 115c, Even if the device is manufactured in a single layer, each light-emitting layer can have an optimized device configuration, resulting in high productivity. A light-emitting element with high luminous efficiency can be realized.

[0032] Next, the light-emitting element shown in FIG. 1(B) will be described below.

[0033] The light-emitting element shown in FIG. 1B has a light-emitting layer 1 between a pair of electrodes (anode 101 and cathode 103). 15, and the light-emitting layer 115 comprises a first phosphorescent material 121a and a first electron-transporting material 122. a first light-emitting layer 115a containing a second phosphorescent material 131a and a second electron-transporting material 131b; a second light-emitting layer 115b including the first light-emitting layer 115a and the second light-emitting layer 115b; a third light-emitting layer 141a covering the first light-emitting layer 141 and including a fluorescent material 141a and a third electron-transporting material 142a; 15c and has.

[0034] The third light-emitting layer 115c is the shade of the first light-emitting layer 115a and the second light-emitting layer 115b. It is provided in contact with the electrode 103 side.

[0035] The first light-emitting layer 115a is made of a first phosphorescent material 121a and a first electron transport material The second hole transport material 122a may further include a first hole transport material 123a. The light-emitting layer 115b includes a second phosphorescent material 131a, a second electron-transporting material 132a, and The second hole transporting material 133a may also be included.

[0036] In addition, in FIG. 1B, in addition to the light-emitting layer 115, a hole injection layer 1 11, first hole transport layer 113a, second hole transport layer 113b, third hole transport layer 113 However, these may be provided as needed. stomach.

[0037] More specifically, the light-emitting device shown in FIG. 1B includes an anode 101 on a substrate 100, and a a hole injection layer 111 on the hole injection layer 111; a first hole transport layer 113a on the hole injection layer 111; a second hole transport layer 113b on the injection layer 111 and a third hole transport layer 113b on the hole injection layer 111; 113c, a first light-emitting layer 115a on the first hole transport layer 113a, and a second hole transport layer a second light-emitting layer 115b on the first light-emitting layer 115a, a second light-emitting layer 115b on the second light-emitting layer 113b, and and a third light-emitting layer 115c on the third hole transport layer 113c, and a third light-emitting layer 115c on the third light-emitting layer 115c. It has an electron injection layer 119 and a cathode 103 on the electron injection layer 119 .

[0038] In the light-emitting element shown in FIG. 1B, the third light-emitting layer 115c is a light-emitting layer and a first light-emitting layer. The second light-emitting layer 115a functions as an electron transport layer for the second light-emitting layer 115b.

[0039] The electron transporting properties of the first electron transporting material 122a and the second electron transporting material 132a are The fluorescent material 141a contained in the third light-emitting layer 115c has high luminescence. The third light-emitting layer 115a and the second light-emitting layer 115b do not contribute to light emission. In the case of c, light is emitted from the fluorescent material 141a contained in the third light-emitting layer 115c. do.

[0040] That is, in the light-emitting element of one embodiment of the present invention, the third light-emitting layer 115c functions as an electron-transporting layer and a light-emitting layer. In order to simultaneously provide the functions of the first light-emitting layer 115a and the second light-emitting layer 115b, In this case, the third light-emitting layer 115c can be commonly used as an electron transport layer. On the hole transport layer 113c, the third light emitting layer 115c can be used as a light emitting layer. Therefore, it is possible to realize a light emitting device with high productivity and high luminous efficiency. In addition, the separate coating process for forming the light-emitting element shown in FIG. 1(B) is performed by coating the first hole transport layer 1 13a, the second hole transport layer 113b and the third hole transport layer 113c are formed on the hole injection layer 111. The first light-emitting layer 115a and the second light-emitting layer 115b are formed on the first hole transport layer 115b. A third light-emitting layer 115c is formed on the first light-emitting layer 113a and the second hole transport layer 113b. The second light-emitting layer 115a, the second light-emitting layer 115b, and the third hole-transporting layer 113c are formed on the second light-emitting layer 115a, the second light-emitting layer 115b, and the third hole-transporting layer 113c. In addition, by forming each hole transport layer and each light emitting layer continuously, the number of times of separate coating can be reduced. For example, the first hole transport layer 113a and the first light emitting layer 115a may be formed successively. Then, the second hole transport layer 113b and the second light emitting layer 115b are formed in succession, and the third hole transport layer Then, the first light-emitting layer 115a, the second light-emitting layer 115b, and the The third light-emitting layer 115c is formed on the third hole transport layer 113c. By separately painting the above, the light-emitting element shown in FIG. 1(B) can be formed. The light-emitting element shown in FIG. 1(A) does not require the step of forming an electron transport layer 117. It is possible to omit it.

[0041] Here, other components of the light-emitting device shown in FIGS. 1(A) and 1(B) will be described in detail below. explain.

[0042] <Substrate> The substrate 100 is used as a support for the light-emitting element. A substrate made of glass, quartz, plastic, or the like may be used. A flexible substrate may also be used. A flexible substrate is a substrate that can be bent (flexible), for example, Plastic substrates made of polycarbonate, polyarylate, polyethersulfone, etc. In addition, films (polypropylene, polyester, polyvinyl fluoride, It is also possible to use inorganic vapor deposition films, etc. Anything other than these may be used as long as it functions as a support in the manufacturing process of the element.

[0043] <Anode> The anode 101 is formed using one or more kinds of conductive metals, alloys, conductive compounds, etc. In particular, it is preferable to use a material with a large work function (4.0 eV or more). For example, indium tin oxide (ITO) , indium tin oxide containing silicon or silicon oxide, indium zinc oxide, oxide Indium oxide containing tungsten and zinc oxide, graphene, gold, platinum, nickel , tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or metallic materials Nitrides (for example, titanium nitride), etc. Also, silver, copper, aluminum, titanium etc. are formed into nanowires (or thin wires), and conductive materials (conductive organic materials, etc.) are placed on top of them. The anode 101 is formed by forming a thin film of a metal oxide (e.g., graphene) by a coating method, a printing method, or the like. Good too.

[0044] <Cathode> The cathode 103 is made of one or more conductive metals, alloys, conductive compounds, etc. In particular, it is possible to use a material with a small work function (3.8 eV or less). For example, an element belonging to Group 1 or 2 of the periodic table (e.g., lithium, cerium, Alkali metals such as sodium, alkaline earth metals such as calcium and strontium, magnesium alloys containing these elements (e.g., Mg-Ag, Al-Li), europium, Rare earth metals such as ytterbium, alloys containing these rare earth metals, aluminum, silver, etc. You can be there.

[0045] <Hole injection layer and hole transport layer> A hole injection layer 111, a first hole transport layer 113a, a second hole transport layer 113b, and a third hole transport layer 113c. As a material having a high hole transporting property used for the hole transporting layer 113c, for example, 4,4'-bis(4,4'-diphenyl ether) [N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB or α-N PD) and N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'- Biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-tris(calcium phosphate) 4,4',4''-Triphenyl-9-benzol-9-yltriphenylamine (TCTA) (N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4', 4''-Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine 4,4'-bis[N-(spiro-9,9'-bifluorene- Aromatic amination of [2-yl]-N-phenylamino]biphenyl (abbreviation: BSPB) Compound, 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9 -phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenyl carbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazole-3 -yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), etc. Others include 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5 -Tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4 -(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: C Carbazole derivatives such as carbazole (zPA) can be used. The substances mentioned here are mainly 10 -6 cm 2 It is a material with a hole mobility of 1 / Vs or more. However, the transport of holes is higher than that of electrons. Any substance other than these may be used as long as it has high transportability.

[0046] Furthermore, a hole injection layer 111, a first hole transport layer 113a, a second hole transport layer 113b, and the third hole transport layer 113c was made of poly(N-vinylcarbazole) (abbreviation: PVK ), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{ N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino} Poly[N,N'-bis(4-butylphenyl)methacrylamide] (abbreviation: PTPDMA) (phenyl)-N,N'-bis(phenyl)benzidine (abbreviation: Poly-TPD), etc. It is also possible to use a polymer compound of the following formula:

[0047] In addition, the hole injection layer 111, the first hole transport layer 113a, the second hole transport layer 113b, and Acceptor materials that can be used for the third hole transport layer 113c include transition metals, Examples of the transition metal oxides include oxides of Group 4 of the periodic table. Oxides of metals belonging to Groups 1 to 8 are preferred. Specifically, molybdenum oxide is particularly preferred. stomach.

[0048] <First light-emitting layer> The first light-emitting layer 115a contains a first phosphorescent material 121a (guest material), a first electron transport a first hole transporting material 122a (host material) and a second hole transporting material 123a (assist material) In addition, the first light-emitting layer 115a preferably emits red light.

[0049] The T1 level of the host material (or assist material) is higher than the T1 level of the guest material. If the T1 level of the host material is lower than the T1 level of the guest material, The host material quenches the triplet excitation energy of the guest material that contributes to light. This is because it leads to a decrease in luminous efficiency.

[0050] In addition, the first phosphorescent material 121a (guest material) and the first electron transporting material 122a (ho The first hole transporting material 123a (assist material) and the first hole transporting material 123b (assist material) are capable of forming an exciplex. The emission spectrum of the exciplex is the same as that of the first phosphorescent material 121a (guess The absorption spectrum of the exciplex overlaps with that of the first phosphorescent material, and the emission spectrum of the exciplex peaks at the first phosphorescent material. It is preferable that the wavelength is longer than the peak of the absorption spectrum of the material 121a (guest material).

[0051] Here, in order to increase the efficiency of energy transfer from the host material to the guest material, The Förster mechanism (dipole-dipole interaction) and the Dexter mechanism are known as the Considering the mechanism (electron exchange interaction), the emission spectrum (singlet excited state) of the host material When discussing energy transfer from the excited triplet state, the fluorescence spectrum is used. -transfer) and the absorption spectrum of the guest material (more specifically, The overlap with the spectrum of the absorption band on the longest wavelength (lowest energy) side becomes large. It is preferable that:

[0052] However, the fluorescence spectrum of the host material is usually determined by the longest wavelength (low energy) of the guest material. It is difficult to superimpose the absorption spectrum on the absorption band on the energy side. In this case, the phosphorescence spectrum of the host material will be longer wavelength (lower wavelength) than the fluorescence spectrum. Since the T1 level of the host material is located on the lower energy side, the T1 level of the phosphorescent compound is lower than that of the This is because the quenching problem described above occurs. To avoid this, the T1 level of the host material is designed to be higher than the T1 level of the phosphorescent compound. This shifts the fluorescence spectrum of the host material to the short wavelength (high energy) side. The fluorescence spectrum is the absorption band of the guest material on the longest wavelength (lowest energy) side. Therefore, the fluorescence spectrum of the host material does not overlap with that of the guest material. The absorption spectrum of the host material is superimposed on the absorption spectrum of the longest wavelength (lowest energy) absorption band of the Maximizing energy transfer from singlet excited states is usually difficult.

[0053] Therefore, the first light-emitting layer 115a included in the light-emitting element of one embodiment of the present invention is made of a guest material. The first phosphorescent material 121a (hereinafter referred to as the first substance) is a first electron transporting material. In addition to the material 122a (referred to as the second substance), a first hole transporting material 123a (referred to as the third substance) The host material and the third substance form an excited complex (also called an exciplex). In this case, the carriers (electrons and Upon recombination of the electron and hole, the host material and the third material form an exciplex.

[0054] As a result, in the light-emitting layer, the fluorescence spectrum of the host material and the fluorescence spectrum of the third material are The energy of the exciplex is converted into the emission spectrum of the exciplex at longer wavelengths. In order to increase the overlap between the emission spectrum of the complex and the absorption spectrum of the guest material, By selecting the host material and the third substance, it is possible to maximize the energy transfer from the singlet excited state. Regarding the triplet excited state, it is possible to increase the excitation energy from the exciplex rather than the host material. It is believed that energy transfer occurs between the two. is an exciplex that utilizes the overlap between the emission spectrum of the exciplex and the absorption spectrum of the phosphorescent compound. Energy transfer can increase the energy transfer efficiency, leading to high external quantum efficiency. Therefore, a light emitting device with high light emission can be realized.

[0055] In addition, the first electron transporting material 122a (host material) and the first hole transporting material 123a When using an assist material, the carrier balance can be controlled by the mixture ratio. Specifically, the first electron transporting material 122a: the first hole transporting material 123a= The weight ratio is preferably in the range of 1:9 to 9:1.

[0056] In addition, energy transfer between exciplexes (exciton diffusion) is difficult to occur, so By using an exciplex in the electron transport layer 117, exciton diffusion to the electron transport layer 117 can be prevented.

[0057] The first phosphorescent material 121a that can be used in the first light-emitting layer 115a is, for example, For example, a phosphorescent material having an emission peak in the range of 600 nm to 700 nm can be used. Examples of the starting material include (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)-2-isobutyryl]methylpropional. [Ir(5mdppm)2(dib m)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethyl Thanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis [4,6-Di(naphthalen-1-yl)pyrimidinate](dipivaloylmethanato)iridi Pyrimidine skeletons such as Ir(III) (abbreviation: [Ir(d1npm)2(dpm)]) and organometallic iridium complexes with (acetylacetonato)bis(2,3,5-trifluoromethyl) (phenylpyrazinate)iridium(III) (abbreviation: [Ir(tppr)2(acac)] ), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium (III) (abbreviation: [Ir(tppr)2(dpm)]), (acetylacetonato)bis [2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation Organometallic iridates with pyrazine skeletons, such as [Ir(Fdpq)2(acac)] complexes and tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ )stomach Lithium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]) Among the above, organometallic iridium complexes having a pyridine skeleton such as Organometallic iridium complexes with pyrimidine skeletons are also outstanding in terms of reliability and luminescence efficiency. In addition, organometallic iridium complexes having a pyrazine skeleton are particularly preferred because they have a high chromaticity. Good red light emission is obtained.

[0058] The first electron transporting material 122a that can be used in the first light-emitting layer 115a is: π-electron deficient heteroaromatic compounds such as nitrogen-containing heteroaromatic compounds are preferred, for example, 2 -(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxa Diazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-t ert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis [5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl] Benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazo 2,2',2'-(2-yl)phenyl]-9H-carbazole (abbreviation: CO11) '-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazoline) 2-[3-(dibenzothiophen-4-yl)phenyl]-1 -phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II) and other polyazo Heterocyclic compounds with an oxadiazole skeleton (oxadiazole derivatives, imidazole derivatives, triazole derivatives) azole derivatives, etc.) and 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo [f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzo Thiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation :2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl] [phenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 4 ,6-Bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6m PnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine ( Heterocyclic compounds (pyrazolidinyl compounds) with a diazine skeleton, such as 4,6mDBTP2Pm-II (abbreviation: 4,6mDBTP2Pm-II) idine derivatives, pyrimidine derivatives, pyridazine derivatives, quinoxaline derivatives, dibenzoquinone derivatives oxaline derivatives, etc.) and 3,5-bis(9H-carbazol-9-yl)phenyl)pyri 3,5DCzPPy, 1,3,5-tri[(3-pyridyl)-phen-3 Heterocyclic compounds (pyridinium compounds) with a pyridine skeleton, such as [-yl]benzene (abbreviation: TmPyPB), Lysine derivatives, quinoline derivatives, dibenzoquinoline derivatives, etc. However, heterocyclic compounds with diazine skeletons and heterocyclic compounds with pyridine skeletons are reliable. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton are preferred. The compound has a high electron transporting property and also contributes to a reduction in driving voltage.

[0059] The first hole transporting material 123a that can be used in the first light-emitting layer 115a is For example, π-electron-rich heteroaromatic compounds (e.g., carbazole derivatives and indole derivatives) and aromatic amine compounds are preferred, for example, 4,4'-bis[N-(1-naphthyl)-N -phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl )-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: T PD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-fluorene phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylphenyl) Fluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3' -(9-Phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP) , 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenyl Amine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9 H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-( 1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenyl Amine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl (9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9, 9-Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl] N-phenyl-N-[ 4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9'- Compounds with an aromatic amine skeleton, such as bifluorene-2-amine (abbreviation: PCBASF) and 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N -carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl) 3,3'-bis(9-phenyl)-9-phenyl-carbazole (abbreviation: CzTP), Compounds with a carbazole skeleton, such as PCCP (9H-carbazole) , 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (Abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H- Fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) , 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyl Compounds with a thiophene skeleton, such as dibenzothiophene (abbreviation: DBTFLP-IV) and 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) ( Abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluorene-9- (I)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) Among the above, compounds having an aromatic amine skeleton are preferred. Compounds having a carbazole skeleton and compounds having a high reliability and high hole transport property are also used. This is preferable because it contributes to reducing the driving voltage.

[0060] <Second light-emitting layer> The second light-emitting layer 115b contains a second phosphorescent material 131a (guest material), a second electron transport a second hole transporting material 132a (host material) and a second hole transporting material 133a (assist material) In addition, the second light-emitting layer 115b preferably emits green light.

[0061] In addition, the second phosphorescent material 131a (guest material) and the second electron transport material 132a (ho The first hole transporting material 133a (assist material) and the second hole transporting material 133b (assist material) are capable of forming an exciplex. The emission spectrum of the exciplex is the same as that of the second phosphorescent material 131a (Guess). The absorption spectrum of the exciplex overlaps with that of the second phosphorescent material, and the emission spectrum of the exciplex peaks at the second phosphorescent material. It is preferable that the wavelength is longer than the peak of the absorption spectrum of the material 131a (guest material). The structure of the exciplex is the same as that of the first light-emitting layer 115a. 15b can also be applied.

[0062] In addition, the second electron transporting material 132a (host material) and the second hole transporting material 133a When using an assist material, the carrier balance can be controlled by the mixture ratio. Specifically, the second electron transporting material 132a: the second hole transporting material 133a= The weight ratio is preferably in the range of 1:9 to 9:1.

[0063] In addition, energy transfer between exciplexes (exciton diffusion) is difficult to occur, so By using an exciplex in the electron transport layer 117, exciton diffusion to the electron transport layer 117 can be prevented.

[0064] The second phosphorescent material 131a that can be used in the second light-emitting layer 115b is, for example, For example, a phosphorescent material having an emission peak in the range of 520 nm to 600 nm can be used. Examples of the material include tris(4-methyl-6-phenylpyrimidinato)iridium (I II) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyridine) Iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylated cetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation :[Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert -butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBup pm)2(acac)]), (acetylacetonato)bis[4-(2-norbornyl)- 6-phenylpyrimidinato]iridium(III) (endo-, exo-mixture) (abbreviation Name: Ir(nbppm)2(acac)), (acetylacetonato)bis[5-methyl- 6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation :[Ir(mpmppm)2(acac)]), (acetylacetonato)bis(4,6- Diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(aca c)]) and organometallic iridium complexes with pyrimidine skeletons, such as (acetylacetonate Nato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation :[Ir(mppr-Me)2(acac)]), (acetylacetonato)bis(5-acetylacetonato)bis(5-acetylacetonato) isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [I Organometallic iridium compounds with pyrazine skeletons, such as r(mppr-iPr)2(acac)] complexes and tris(2-phenylpyridinato-N,C 2’ ) Iridium(III)( Abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’ ) Irijiu Ir(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis (Benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir (bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III ) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ )stomach Lithium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N ,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(ac ac)]) and other organometallic iridium complexes having a pyridine skeleton. Among these, organometallic iridium complexes with pyrimidine skeletons are particularly reliable and highly efficient. It is especially preferable because it is superior.

[0065] The second electron transporting material 132a that can be used in the second light-emitting layer 115b is: The same material as the material shown in the first electron transporting material 122a can be used. The second hole transport material 133a that can be used in the second light emitting layer 115b is The same materials as those shown as the hole transporting material 123a can be used.

[0066] <Third light-emitting layer> The third light-emitting layer 115c includes a fluorescent material 141a (guest material) and a third electron-transporting The third light-emitting layer 115c includes a material 142a (host material). It is preferable to show

[0067] The fluorescent material 141a that can be used in the third light-emitting layer 115c is N,N'- Bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-difluor Phenyl-pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis( 3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene-9- (I)phenyl)-pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn) , N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenyl Phenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol- (10-phenyl-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation :YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl N,9-diphenyl-2-anthryltriphenylamine (abbreviation: 2YGAPPA) N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole 3-Amine (abbreviation: PCAPA), Perylene, 2,5,8,11-tetra-tert-butyl Thiperylene (TBP), 4-(10-phenyl-9-anthryl)-4'-(9 -phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA In particular, fluorescent compounds having a pyrene skeleton have a high hole trapping property, It is preferable because it has excellent luminescence efficiency and reliability. Condensed aromatic diamine compounds, such as pyrenediamine compounds like emFLPAPrn, The material is preferred because it has a high hole trapping property, and is excellent in luminous efficiency and reliability.

[0068] The third electron-transporting material 142a that can be used in the third light-emitting layer 115c is: For example, an organic compound containing an anthracene skeleton is preferred. Examples of the compound include 9-[4-(10-phenyl-9-anthracenyl)phenyl ]-9H-carbazole (abbreviation: CzPA), 9-phenyl-3-[4-(10-phenyl [(9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6- Diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carba DPCzPA (abbreviation: DPCzPA), 9,10-bis(3,5-diphenylphenyl) ant Helical anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA ), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: tB It is preferable to use compounds that have electron transport properties but also readily accept holes, such as uDNA. In the light-emitting element of one embodiment of the present invention, the third electron-transporting material 142a is an The compound having a thracene skeleton is preferred because it not only has electron transport properties but also easily accepts holes. It's nice.

[0069] <Electron transport layer> The electron transport layer 117 is a layer containing a substance with a high electron transport property. The triplet excitation energy levels of the materials forming the first light-emitting layer 115a and the second light-emitting layer The first electron transport material 122a and the second electron transport material 132a used in 115b The energy level of the third light-emitting layer is lower than that of the first light-emitting layer. The same material as the third electron transporting material 142a that can be used for 115c is used. can be done.

[0070] <Electron injection layer> The electron injection layer 119 is a layer containing a substance with high electron injection properties. Lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2) Alkali metal or alkaline earth metal compounds such as lithium oxide (LiOx), etc. Also, rare earth metal compounds such as erbium fluoride (ErF3) can be used. can be used.

[0071] Alternatively, the electron injection layer 119 may be formed by mixing an organic compound and an electron donor. Composite materials may also be used. Such composite materials are made by adding electrons to organic compounds via electron donors. In this case, the organic compound is The electron donor is preferably a material that is excellent in transporting the generated electrons. Any substance that exhibits electron donating properties to organic compounds is acceptable. Preferred are lithium earth metals and rare earth metals, and lithium, cesium, magnesium, calcium, Examples include erbium and ytterbium. In addition, alkali metal oxides and alkaline earth metals Metal oxides are preferred, and examples thereof include lithium oxide, calcium oxide, and barium oxide. Lewis bases such as magnesium oxide can also be used. Organic compounds such as thiafulvalene (abbreviation: TTF) can also be used.

[0072] The hole injection layer 111, the first hole transport layer 113a, and the second hole transport layer 11 3b, a third hole transport layer 113c, a first light-emitting layer 115a, a second light-emitting layer 115b, a third The light-emitting layer 115c, the electron transport layer 117, and the electron injection layer 119 are each formed by evaporation ( The layer can be formed by a method such as a vacuum deposition method, an ink jet method, or a coating method.

[0073] In addition, the first light-emitting layer 115a, the second light-emitting layer 115b, and the third light-emitting layer 115c of the light-emitting element described above The light emitted from the light-emitting layer 115c is emitted from either or both of the anode 101 and the cathode 103. Therefore, the anode 101 and the cathode 102 in this embodiment are taken out to the outside. Either one or both of the electrodes 03 is a light-transmitting electrode.

[0074] Note that the structure shown in this embodiment mode may be combined as appropriate with structures shown in other embodiment modes or examples. It can be adjusted.

[0075] (Embodiment 2) In this embodiment, a modified example of the light-emitting element of one embodiment of the present invention shown in FIG. 2 and 3. Note that the same parts as those shown in the previous embodiment or the same parts as those shown in the previous embodiment will be described. The parts having the same functions are denoted by the same reference numerals, and detailed explanations thereof will be omitted.

[0076] The light-emitting element shown in FIG. 2(A) has a light-emitting layer 1 between a pair of electrodes (anode 101 and cathode 103). 15, and the light-emitting layer 115 comprises a first phosphorescent material 121a and a first electron-transporting material 122. a first light-emitting layer 115a containing a second phosphorescent material 131a and a second electron-transporting material 131b; a second light-emitting layer 115b containing a fluorescent material 141a and a third electron-transporting material 14 and a third light-emitting layer 115c including 2a.

[0077] In addition, each of the first light-emitting layer 115a, the second light-emitting layer 115b, and the third light-emitting layer 115c This is provided in contact with the electron transport layer 117 arranged on the cathode 103 side.

[0078] The first light-emitting layer 115a is made of a first phosphorescent material 121a and a first electron transport material The second hole transport material 122a may further include a first hole transport material 123a. The light-emitting layer 115b includes a second phosphorescent material 131a, a second electron-transporting material 132a, and The second hole transporting material 133a may also be included.

[0079] In FIG. 2(A), a light-emitting layer 115 and an electron transport layer 117 are provided between a pair of electrodes. In addition, a hole injection layer 111, a first hole transport layer 113a, a second hole transport layer 113b, a third hole transport layer 113c, a fourth hole transport layer 113d, a fifth hole transport layer 113e, a sixth hole transport layer 113f, a sixth hole transport layer 113g, a sixth hole transport layer 113h, a sixth hole transport layer 113i, a sixth hole transport layer 113j, a sixth hole transport layer A fourth hole transport layer 113d and an electron injection layer 119 are formed on the first and second layers.

[0080] More specifically, the light-emitting device shown in FIG. 2A includes an anode 101 on a substrate 100, and a a hole injection layer 111 on the hole injection layer 111; a fourth hole transport layer 113d on the hole injection layer 111; the first hole transport layer 113a on the hole transport layer 113d, and the fourth hole transport layer 113d on the a second hole transport layer 113b, a first light-emitting layer 115a on the first hole transport layer 113a; The second light-emitting layer 115b on the second hole transport layer 113b and the fourth light-emitting layer 115c on the fourth hole transport layer 113d The third light-emitting layer 115c, the first light-emitting layer 115a, the second light-emitting layer 115b, and the third light-emitting layer 115c. An electron transport layer 117 on the light-transporting layer 115c, an electron injection layer 119 on the electron transport layer 117, and an electron and a cathode 103 on the injection layer 119.

[0081] Next, the light-emitting element shown in FIG. 2(B) will be described below.

[0082] The light-emitting element shown in FIG. 2(B) has a light-emitting layer 1 between a pair of electrodes (anode 101 and cathode 103). 15, and the light-emitting layer 115 comprises a first phosphorescent material 121a and a first electron-transporting material 122. a first light-emitting layer 115a containing a second phosphorescent material 131a and a second electron-transporting material 131b; a second light-emitting layer 115b including the first light-emitting layer 115a and the second light-emitting layer 115b; a third light-emitting layer 141a covering the first light-emitting layer 141 and including a fluorescent material 141a and a third electron-transporting material 142a; 15c and has.

[0083] The third light-emitting layer 115c is the shade of the first light-emitting layer 115a and the second light-emitting layer 115b. It is provided in contact with the electrode 103 side.

[0084] The first light-emitting layer 115a is made of a first phosphorescent material 121a and a first electron transport material The second hole transport material 122a may further include a first hole transport material 123a. The light-emitting layer 115b includes a second phosphorescent material 131a, a second electron-transporting material 132a, and The second hole transporting material 133a may also be included.

[0085] In addition, in FIG. 2B, in addition to the light-emitting layer 115, a hole injection layer 1 11, first hole transport layer 113a, second hole transport layer 113b, fourth hole transport layer 113 d, and an electron injection layer 119 are formed.

[0086] More specifically, the light-emitting device shown in FIG. 2B includes an anode 101 on a substrate 100 and a a hole injection layer 111 on the hole injection layer 111; a fourth hole transport layer 113d on the hole injection layer 111; the first hole transport layer 113a on the hole transport layer 113d, and the fourth hole transport layer 113d on the a second hole transport layer 113b, a first light-emitting layer 115a on the first hole transport layer 113a; The second light-emitting layer 115b on the second hole transport layer 113b, the first light-emitting layer 115a, the second a third light-emitting layer 115c on the light-emitting layer 115b and the fourth hole-transporting layer 113d; The light emitting device has an electron injection layer 119 on the optical layer 115c and a cathode 103 on the electron injection layer 119.

[0087] The light-emitting element shown in FIGS. 2A and 2B is different from the light-emitting element shown in FIGS. 1A and 1B in the following respects. As a result, a fourth hole transport layer 113d is provided on the hole injection layer 111. The light-emitting layer 115c does not include the third hole transport layer 113c. The light-emitting layer 115c is provided in contact with the fourth hole transport layer 113d. The material that can be used for the hole transport layer 113d is the same as that for the third hole transport layer 113c. Fees can be used.

[0088] The fourth hole transport layer 113d is a layer including the first light-emitting layer 115a, the second light-emitting layer 115b, and 2(A) and 2(B) can be used in common for the light-emitting layer 115c of FIG. The light-emitting element shown in FIG. 1B has the excellent effect of the light-emitting element of one embodiment of the present invention shown in FIG. In addition, the productivity in forming the light-emitting element can be further improved. The coating process for forming the optical element is to coat the first hole transport layer 113a and the second hole transport layer 113b. This results in a first light-emitting layer 115a, a second light-emitting layer 115b, and a third light-emitting layer 115c. In addition, by forming each hole transport layer and each light emitting layer continuously, the number of times of separate coating can be reduced. For example, the first hole transport layer 113a and the first light emitting layer 115a may be formed successively. The second hole transport layer 113b and the second light emitting layer 115b are connected to each other, and the third light emitting layer 115c is connected to the second hole transport layer 113b. Therefore, the light emitting element shown in FIG. 2(A) is formed by applying the coating three times in total. In addition, the separate coating process for forming the light-emitting element shown in FIG. 2(B) can be performed by applying the first hole transport a first hole transport layer 113a, a second hole transport layer 113b, a first light emitting layer 115a, and a second light emitting layer 116b. In addition, by forming each hole transport layer and each light emitting layer continuously, the number of times of coating can be reduced. For example, the first hole transport layer 113a and the first light emitting layer 115 a) is formed successively, and the second hole transport layer 113b and the second light emitting layer 115b are formed successively. Therefore, the light-emitting element shown in FIG. 2(B) can be formed by applying the coating two times in total. can.

[0089] In the light-emitting element shown in FIGS. 2A and 2B, the first light-emitting layer 115a and The two light-emitting layers 115b each independently comprise a first hole transport layer 113a and a second hole transport layer 113b. Therefore, it is possible to obtain an optimum element configuration for each light-emitting layer. As a result, a light-emitting element with high luminous efficiency can be realized in each of the light-emitting layers.

[0090] In the light-emitting element shown in FIGS. 2A and 2B, the first hole-transporting layer 113a and the second hole-transporting layer 113b are By adjusting the film thickness of the second hole transport layer 113b and the fourth hole transport layer 113d, , the optical path length in each light-emitting layer can be adjusted.

[0091] Next, the light-emitting element shown in FIG. 3(A) will be described below.

[0092] The light-emitting element shown in FIG. 3A has a light-emitting layer 1 between a pair of electrodes (anode 101 and cathode 103). 15, and the light-emitting layer 115 comprises a first phosphorescent material 121a and a first electron-transporting material 122. a first light-emitting layer 115a containing a second phosphorescent material 131a and a second electron-transporting material 131b; a second light-emitting layer 115b containing a fluorescent material 141a and a third electron-transporting material 14 and a third light-emitting layer 115c including 2a.

[0093] In addition, each of the first light-emitting layer 115a, the second light-emitting layer 115b, and the third light-emitting layer 115c This is provided in contact with the electron transport layer 117 arranged on the cathode 103 side.

[0094] The first light-emitting layer 115a is made of a first phosphorescent material 121a and a first electron transport material The second hole transport material 122a may further include a first hole transport material 123a. The light-emitting layer 115b includes a second phosphorescent material 131a, a second electron-transporting material 132a, and The second hole transporting material 133a may also be included.

[0095] In addition, in FIG. 3A, a hole injection layer 115 is also provided between the pair of electrodes. 11, a hole transport layer 113, and an electron injection layer 119 are formed.

[0096] More specifically, the light-emitting device shown in FIG. 3A includes an anode 101 on a substrate 100, and a A hole injection layer 111 on the hole injection layer 111, a hole transport layer 113 on the hole injection layer 111, and a hole transport layer 114 on the hole injection layer 111. a first light-emitting layer 115a on the hole-transporting layer 113, a second light-emitting layer 115b on the hole-transporting layer 113, and a hole The third light-emitting layer 115c on the transport layer 113, the first light-emitting layer 115a, the second light-emitting layer 115 b, the electron injection layer 119 on the third light-emitting layer 115c, and the cathode 10 on the electron injection layer 119. 3 and has.

[0097] Next, the light-emitting element shown in FIG. 3(B) will be described below.

[0098] The light-emitting element shown in FIG. 3B has a light-emitting layer 1 between a pair of electrodes (anode 101 and cathode 103). 15, and the light-emitting layer 115 comprises a first phosphorescent material 121a and a first electron-transporting material 122. a first light-emitting layer 115a containing a second phosphorescent material 131a and a second electron-transporting material 131b; a second light-emitting layer 115b including the first light-emitting layer 115a and the second light-emitting layer 115b; a third light-emitting layer 141a covering the first light-emitting layer 141 and including a fluorescent material 141a and a third electron-transporting material 142a; 15c and has.

[0099] The third light-emitting layer 115c is the shade of the first light-emitting layer 115a and the second light-emitting layer 115b. It is provided in contact with the electrode 103 side.

[0100] The first light-emitting layer 115a is made of a first phosphorescent material 121a and a first electron transport material The second hole transport material 122a may further include a first hole transport material 123a. The light-emitting layer 115b includes a second phosphorescent material 131a, a second electron-transporting material 132a, and The second hole transporting material 133a may also be included.

[0101] In addition, in FIG. 3B, in addition to the light-emitting layer 115, a hole injection layer 1 11, a hole transport layer 113, and an electron injection layer 119 are formed.

[0102] More specifically, the light-emitting device shown in FIG. 3B includes an anode 101 on a substrate 100 and a A hole injection layer 111 on the hole injection layer 111, a hole transport layer 113 on the hole injection layer 111, and a hole transport layer 114 on the hole injection layer 111. a first light-emitting layer 115a on the hole transport layer 113, a second light-emitting layer 115b on the hole transport layer 113, and a first The third light-emitting layer 115a, the second light-emitting layer 115b, and the hole-transporting layer 113 are formed on the first light-emitting layer 115a, the second light-emitting layer 115b, and the hole-transporting layer 113. 5c, an electron injection layer 119 on the third light-emitting layer 115c, and a cathode 10 on the electron injection layer 119. 3 and has.

[0103] The light-emitting element shown in FIGS. 3A and 3B is different from the light-emitting element shown in FIGS. 1A and 1B in that As a result, a hole transport layer 113 is provided on the hole injection layer 111. Layer 113 includes a first light-emitting layer 115a, a second light-emitting layer 115b, and a third light-emitting layer 115c. It can be used as a common hole transport layer for the hole transport layer 113. The material that can be used for the third hole transport layer 113c can be the same as that for the third hole transport layer 113c. The light-emitting element shown in FIGS. 3A and 3B is a light-emitting element according to one embodiment of the present invention shown in FIGS. In addition to the excellent effects of the light emitting device, the productivity during the formation of the light emitting device can be further improved. In the separate coating process shown in FIG. 3A, the first light-emitting layer 115a, the second light-emitting layer 115b, and the The light-emitting layer 115b and the third light-emitting layer 115c are formed three times in total. In the separate coating process shown in FIG. 1, the first light-emitting layer 115a and the second light-emitting layer 11 This makes it 5b, for a total of two repetitions.

[0104] However, in the device configuration shown in FIGS. 3(A) and 3(B), the first light-emitting layer 115a and the second light-emitting layer 115b are The first light-emitting layer 115b and the third light-emitting layer 115c share the hole transport layer 113. Therefore, the first light-emitting layer 115a, the second light-emitting layer 115b, and the third light-emitting layer 115c In one or two of these cases, the device characteristics may be degraded. When productivity is prioritized over cost, the configurations shown in FIGS. 3(A) and 3(B) may be applied. In the configuration shown in FIGS. 3(A) and 3(B), the first electron transporting material 122a and The second electron-transporting material 132a and the third light-emitting layer 115c have very high electron-transporting properties. Therefore, even when a common hole transport layer is used for each light-emitting layer, the element on the electron transport layer side There is no or very little degradation in molecular properties, resulting in well-balanced emission across multiple light-emitting layers. It may be an optical element.

[0105] In the light-emitting element shown in FIGS. 3A and 3B, the first light-emitting layer 115a and the second light-emitting layer 115b are The light-emitting layer 115b and the third light-emitting layer 115c have a common anode 101 below. For example, the first light-emitting layer 115a, the second light-emitting layer 115b, and the The light emitting layer 115b and the third light emitting layer 115c are formed independently of each other by forming the anode 101 with different thicknesses. For example, the anode 101 may have a different thickness from the first anode 101. The first light-emitting layer 115a, the second light-emitting layer 115b, and the third light-emitting layer 115c are stacked on the anode 101 in this order. The thickness can be increased.

[0106] In the light-emitting devices shown in FIGS. 3A and 3B, a common hole transport layer 1 is used in each light-emitting layer. 13 is used, the structure for adjusting the optical path length by the film thickness of the anode 101 is This is one of the configurations useful for improving the device characteristics.

[0107] Note that the structure shown in this embodiment mode may be combined as appropriate with structures shown in other embodiment modes or examples. It can be adjusted.

[0108] (Embodiment 3) In this embodiment, a light-emitting device manufactured using a light-emitting element according to one embodiment of the present invention will be described. This will be explained with reference to FIG.

[0109] 4A and 4B show a light-emitting device having first to third light-emitting layers between a cathode and an anode. 2 is a cross-sectional view of a device 250 and a light-emitting device 260. FIG.

[0110] First, the light emitting device 250 shown in FIG. 4(A) will be described below.

[0111] The light emitting device 250 is configured to extract light from the substrate 200 side (the side indicated by the arrow in FIG. 4(A)). This is a light emitting device with a so-called bottom emission structure.

[0112] The light emitting device 250 has an anode 201a, an anode 201b, and an anode 201c, which are separated into island shapes on the substrate 200. The substrate 200 is made of the same material as the substrate 100 in the first embodiment. The anodes 201a, 201b, and 201c can be the same as those shown in the first embodiment. The anodes 201a, 201b, and 201c can be made of the material shown in FIG. The thickness of each element that emits a different color may be different. In this case, since the light emitting device has a bottom emission structure, the anodes 201a, 201b, and 20 1c is formed using a material that is transparent to visible light (for example, ITO, etc.). good.

[0113] The light emitting device 250 also includes partitions 251a, 251b, 251c, and 251d. The wall 251a covers one end of the anode 201a. The partition wall 251c covers the other end of the anode 201b and one end of the anode 201b. The partition wall 251d covers the other end of the anode 201b and one end of the anode 201c. The partition walls 251a, 251b, 251c, and 251d are made of an organic resin or As the organic resin, for example, polyimide resin, Polyamide resin, acrylic resin, siloxane resin, epoxy resin, or phenolic resin Examples of inorganic insulating materials include silicon oxide and silicon oxynitride. This makes it easy to manufacture the partition walls 251a, 251b, 251c, and 251d. Therefore, it is particularly preferable to use a photosensitive resin.

[0114] The light emitting device 250 also includes anodes 201a, 201b, and 201c and partition walls 251a, 251b, and 251c. The hole injection layer 211 is formed on the layers 251b, 251c, and 251d. The materials shown for the hole injection layer 111 in embodiment 1 can be used.

[0115] The light emitting device 250 also has first positive electrodes separated into islands on the hole injection layer 211. a hole transport layer 213a, a second hole transport layer 213b, and a third hole transport layer 213c. In addition, the first hole transport layer 213a, the second hole transport layer 213b, and the third hole transport layer 213c, a first light-emitting layer 215a, a second light-emitting layer 215b, and a third light-emitting layer 215c are formed on the first light-emitting layer 215a, the second light-emitting layer 215b, and the third light-emitting layer 215c, respectively. The first hole transport layer 213a, the second hole transport layer 213b, the third hole transport layer 215c, The hole transport layer 213c, the first light-emitting layer 215a, the second light-emitting layer 215b, and the third light-emitting layer 215c are 15c are the first hole transport layer 113a and the second hole transport layer 114a shown in Embodiment 1, respectively. 13b, a third hole transport layer 113c, a first light-emitting layer 115a, a second light-emitting layer 115b, and The materials shown in the table for the third light-emitting layer 115c can be used.

[0116] The first light-emitting layer 215a is the same as the first light-emitting layer 115a shown in FIG. The light-emitting device includes a first phosphorescent material, a first electron transport material, and a first hole transport material. The second light-emitting layer 215b is made of a second phosphorus, similar to the second light-emitting layer 115b shown in FIG. 1(A). The light-transmitting layer includes a first light-transmitting material, a second electron-transporting material, and a second hole-transporting material. The light-emitting layer 215c is made of a fluorescent material and a fluorescing material, similar to the third light-emitting layer 115c shown in FIG. and a third electron transporting material. Therefore, a first phosphorescent material, a first electron transport material, a first hole transport material, a second phosphorescent material, a second electron transporting material, a second hole transporting material, a fluorescent material, and a third electron transporting material The materials are omitted from the illustration.

[0117] The light emitting device 250 also includes a first light emitting layer 215a, a second light emitting layer 215b, and a third light emitting layer 215c. The electron transport layer 217 is provided on the light emitting layer 215c. The cathode 203 is disposed on the electron injection layer 219. The electron transport layer 17 can be formed using the materials described for the electron transport layer 117 in Embodiment 1. For the electron-injecting layer 219, the materials shown for the electron-injecting layer 119 in Embodiment 1 can be used. The cathode 203 can be formed using the material described for the cathode 103 in Embodiment 1. The light emitting device 250 has a bottom emission structure, so the cathode 203 It is preferable that the light source 100 is made of a material having particularly reflective properties (for example, aluminum).

[0118] In addition, in FIG. 4(A), a configuration in which the anode is placed below and the cathode is placed above is explained. However, the present invention is not limited to this, and for example, the anode may be arranged above and the cathode may be arranged below. In this case, the hole injection layer, the hole transport layer, the light emitting layer, the electron injection layer, and the The lamination order of the electron transport layer and the electron transport layer may be reversed.

[0119] The first light-emitting layer 215a, the second light-emitting layer 215b, and the third light-emitting layer 215c of the light-emitting device 250 The material 15c is provided in contact with the electron transport layer 217. The triplet excitation energy level of the electron transporting material and the The triplet excited energy level of the second electron transporting material contained in the second light-emitting layer 215b is higher than that of the first light-emitting layer 215a. In this way, each light-emitting element included in the light-emitting device 250 has a light-emitting layer that shares a common electron transport layer. Even when using a photodiode, the device has an optimal configuration, resulting in low drive voltage and high current efficiency. Therefore, it is possible to provide a light emitting device 250 with low power consumption or a long life. Furthermore, since a common electron transport layer is used, the light-emitting device can be manufactured with high productivity. 250 can be offered.

[0120] Next, a light emitting device 260 shown in FIG. 4(B) will be described below.

[0121] The light emitting device 260 is a modified example of the light emitting device 250, and emits light from the side indicated by the arrow in FIG. 4(B). This light emitting device has a so-called top emission structure, which allows the light to be removed.

[0122] The light emitting device 260 also includes reflective electrodes 253 on the substrate 200, each of which is separated into an island shape. The reflective electrodes 253a, 253b, and 253c are provided with: Each of the light emitting devices 260 has anodes 201a, 201b, and 201c separated into island shapes. In this case, since the light emitting device has a top emission structure, the reflective electrodes 253a and 253b are b, 253c are made of reflective material (e.g., aluminum or silver) It would be good to achieve it.

[0123] The light emitting device 260 also includes partitions 251a, 251b, 251c, and 251d. The wall 251a covers one end of the reflective electrode 253a and the anode 201a. 1b is the other end of the reflective electrode 253a and the anode 201a, and the other end of the reflective electrode 253b and the anode The partition wall 251c covers one end of the reflective electrode 253b and the anode 201b. b, and one end of the reflective electrode 253c and the anode 201c. 251d covers the other end of the reflective electrode 253c and the anode 201c.

[0124] The light emitting device 260 also includes anodes 201a, 201b, and 201c and partition walls 251a and 251b. A hole injection layer 211 is provided on the layers 251b, 251c, and 251d.

[0125] The light emitting device 260 also has first positive electrodes separated into islands on the hole injection layer 211. a hole transport layer 213a, a second hole transport layer 213b, and a third hole transport layer 213c. In addition, the first hole transport layer 213a, the second hole transport layer 213b, and the third hole transport layer 213c, a first light-emitting layer 215a, a second light-emitting layer 215b, and a third light-emitting layer 215c are formed on the first light-emitting layer 215a, the second light-emitting layer 215b, and the third light-emitting layer 215c, respectively. It has a layer 215c.

[0126] The first light-emitting layer 215a is formed of the first light-emitting layer 115a shown in FIG. The light-emitting device includes a first phosphorescent material, a first electron transport material, and a first hole transport material. The second light-emitting layer 215b is made of a second phosphorus, similar to the second light-emitting layer 115b shown in FIG. 1(A). The light-transmitting layer includes a first light-transmitting material, a second electron-transporting material, and a second hole-transporting material. The light-emitting layer 215c is made of a fluorescent material and a fluorescing material, similar to the third light-emitting layer 115c shown in FIG. and a third electron transporting material. Therefore, a first phosphorescent material, a first electron transport material, a first hole transport material, a second phosphorescent material, a second electron transport material, a second hole transport material, a fluorescent material, and a third electron transport material is omitted in the illustration.

[0127] The light emitting device 260 also includes a first light emitting layer 215a, a second light emitting layer 215b, and a third light emitting layer 215c. The electron transport layer 217 is provided on the light emitting layer 215c. The electron injection layer 219 has a semi-transmitting / semi-reflective layer that functions as a cathode. The semi-transmissive / semi-reflective electrode 253 is, for example, a thin metal film (preferably 2 0 nm or less, more preferably 10 nm or less) and a conductive metal oxide are laminated to form the conductive layer. The thin metal film can be made of silver, magnesium, or alloys containing these metal materials. The conductive metal oxide can be formed by a single layer or a multilayer structure of gold or the like. Indium (In2O3), tin oxide (SnO2), zinc oxide (ZnO), ITO, oxide Indium zinc oxide (In2O3-ZnO), or these metal oxide materials with silicon oxide It is possible to use a material containing kon.

[0128] The light emitting device 260 is a top emission light emitting device, so the reflective electrode The optical resonance effect is utilized between 253a, 253b, 253c and the semi-transparent / semi-reflective electrode 253. The micro-optical resonator (microcavity) is used to increase the light intensity at a specific wavelength. The function of this microcavity can be realized by the reflective electrode 253a, The material sandwiched between 253b, 253c and the semi-transmissive / semi-reflective electrode 253, or the optical path length, etc. For example, the anodes 201a, 201b, and 201c, the first hole The thicknesses of the transport layer 213a, the second hole transport layer 213b, and the third hole transport layer 213c are adjusted. By adjusting the wavelength, the intensity of light emitted from each light-emitting layer can be increased. In device 260, first hole transport layer 213a, second hole transport layer 213b, and third hole transport layer 213c are provided. 2 illustrates a configuration in which the optical path length is adjusted by the film thickness of the hole transport layer 213c.

[0129] In addition, in FIG. 4(B), a configuration in which the anode is placed below and the cathode is placed above is explained. However, the present invention is not limited to this, and for example, the anode may be arranged above and the cathode may be arranged below. In this case, the hole injection layer, the hole transport layer, the light emitting layer, the electron injection layer, and the The lamination order of the electron transport layer and the electron transport layer may be reversed.

[0130] The first light-emitting layer 215a, the second light-emitting layer 215b, and the third light-emitting layer 215c of the light-emitting device 260 The material 15c is provided in contact with the electron transport layer 217. The triplet excitation energy level of the electron transporting material and the The triplet excited energy level of the second electron transporting material contained in the second light-emitting layer 215b is higher than that of the first light-emitting layer 215a. In this way, each light-emitting element included in the light-emitting device 260 has a light-emitting layer that shares a common electron transport layer. Even when using a photodiode, the device has an optimal configuration, resulting in low drive voltage and high current efficiency. Therefore, it is possible to provide a light emitting device 260 with low power consumption or a long life. Furthermore, since a common electron transport layer is used, the light-emitting device can be manufactured with high productivity. 260 can be provided.

[0131] The light emitting device 250 shown in FIG. 4(A) and the light emitting device 260 shown in FIG. 4(B) are made of a substrate. Although the configuration in which only the light emitting element is formed on the substrate 200 has been exemplified, the present invention is not limited to this. For example, a transistor (for example, a TFT) may be separately formed on the substrate 200, and the transistor may be and anodes 201a, 201b, and 201c or reflective electrodes 253a, 253b, and 253c. It is preferable to electrically connect the

[0132] Here, a method for manufacturing the light-emitting device 250 shown in FIG. 4(A) will be described below.

[0133] First, a conductive film is formed on the substrate 200, and the conductive film is processed into a desired shape to form the anode 2. Next, the substrate 200 and the anodes 201a, 201b, and 201c are formed. , 201c, and the partition walls 251a, 251b, 251c, and 251d are formed on the anode 2. The partitions 251a, 251b, 251c, and 251d are It is preferable to form it in the transistor manufacturing process.

[0134] Furthermore, the structure of the transistor is not limited, and a top-gate transistor may be used. Alternatively, a bottom gate transistor such as an inverted staggered transistor may be used. A n-channel transistor or a p-channel transistor may be used. There is no particular limitation on the material used for the transistor. For example, silicon or In-Ga- Applying transistors that use oxide semiconductors such as Zn-based metal oxides in the channel formation region It is possible.

[0135] Next, the anodes 201a, 201b, and 201c and the partition walls 251a, 251b, 251c, and The hole injection layer 211 is formed on the anode 51d. using a method (including vacuum deposition), sputtering, coating, or inkjet method The hole injection layer 211 can be formed by a deposition method (including a vacuum deposition method), a transfer method, or the like. The film can be formed by a method such as a printing method, an ink jet method, or a coating method.

[0136] Next, the first hole transport layer 21 is formed at a position in contact with the hole injection layer 211 and overlapping with the anode 201a. The first hole transport layer 213a is formed by a deposition method (including a vacuum deposition method), a transfer method, The film can be formed by a printing method, an ink jet method, a coating method, or the like. In this case, the deposition method is used, and a deposition mask (metal mask, fine metal mask, or shield The desired area is formed using a dough mask.

[0137] Next, the first light-emitting layer 215a is formed on the first hole transport layer 213a. 215a includes deposition methods (including vacuum deposition methods), transfer methods, printing methods, inkjet methods, and coating methods. In this embodiment, a deposition method is used, and a deposition mask is formed. (also called metal mask, fine metal mask, or shadow mask) The first hole transport layer 213a and the first light emitting layer 215a are formed in the same region. It is preferable to form the layers successively using the deposition mask of the above.

[0138] Next, the second hole transport layer 21 is formed at a position in contact with the hole injection layer 211 and overlapping with the anode 201b. The second hole transport layer 213b is formed in the same manner as the first hole transport layer 213a. It can be formed using:

[0139] Next, the second light-emitting layer 215b is formed on the second hole-transporting layer 213b. The first light-emitting layer 215b can be formed using the same method as that for the first light-emitting layer 215a. The second hole transport layer 213b and the second light emitting layer 215b are successively formed using the same deposition mask. It is preferable to form the layers one after the other.

[0140] Next, the third hole transport layer 21 is formed at a position in contact with the hole injection layer 211 and overlapping with the anode 201c. The third hole transport layer 213c is formed in the same manner as the first hole transport layer 213a. It can be formed using:

[0141] Next, the third light-emitting layer 215c is formed on the third hole-transporting layer 213c. The first light-emitting layer 215c can be formed using the same method as that for the first light-emitting layer 215a. The third hole transport layer 213c and the third light emitting layer 215c are successively formed using the same deposition mask. It is preferable to form the layers one after the other.

[0142] Next, the hole injection layer 211, the first light-emitting layer 215a, the second light-emitting layer 215b, and the third light-emitting layer 215c are An electron transport layer 217 is formed on the light-emitting layer 215c, and then electrons are injected onto the electron transport layer 217. The electron transport layer 217 and the electron injection layer 219 are formed by evaporation (vacuum evaporation). The layer can be formed by a method such as a transfer method, a printing method, an ink jet method, or a coating method.

[0143] Next, the cathode 203 is formed on the electron injection layer 219. The cathode 203 is formed by a vapor deposition method (vacuum deposition) (including the deposition method), sputtering method, coating method, or ink-jet method. can be done.

[0144] In this manner, the light-emitting device 250 shown in FIG. 4A can be manufactured.

[0145] Furthermore, a light-emitting device 260 shown in FIG. 4B is fabricated by the same process as the light-emitting device 250 described above, but Reflecting electrodes 253a, 253b, and 253c are formed below the electrodes 201a, 201b, and 201c. and a step of forming a semi-transmissive and semi-reflective electrode 253 instead of the cathode 203. It can be formed by

[0146] Note that the structure shown in this embodiment mode may be combined as appropriate with structures shown in other embodiment modes or examples. It can be adjusted.

[0147] (Fourth embodiment) In this embodiment, various light-emitting elements or light-emitting devices according to one embodiment of the present invention are fabricated. An example of such an electronic device and lighting device will be described with reference to FIG.

[0148] Examples of electronic devices include television sets (televisions or television receivers) (also known as computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game consoles , portable information terminals, audio playback devices, large game machines such as pachinko machines, etc.

[0149] By fabricating the light-emitting element of one embodiment of the present invention over a flexible substrate, it is possible to fabricate a light-emitting element having a curved surface. It is possible to realize electronic devices and lighting devices having a light-emitting portion.

[0150] Furthermore, the pair of electrodes included in the light-emitting element of one embodiment of the present invention may be made of a material having a light-transmitting property to visible light. By forming the material, electronic devices and lighting devices with see-through light-emitting parts can be realized. It is possible.

[0151] Furthermore, a light-emitting device to which one embodiment of the present invention is applied can also be used for automobile lighting. For example, lighting can be installed on the dashboard, windshield, ceiling, etc.

[0152] FIG. 5A shows an example of a television device. The television device 7100 includes: A display unit 7103 is built into the housing 7101. The display unit 7103 displays images. The light-emitting device can be used in the display portion 7103. 7 shows a configuration in which a housing 7101 is supported by a stand 7105.

[0153] The television device 7100 can be operated using an operation switch provided on the housing 7101 or a separate remote control. This can be done by using the remote control operation device 7110. The channel and volume can be controlled by the -7109, and the information displayed on the display 7103 In addition, the remote control unit 7110 can be used to control the video. A display unit 7107 for displaying information output from the device 7110 may be provided.

[0154] The television device 7100 includes a receiver, a modem, and the like. It is possible to receive general television broadcasts by this, and furthermore, it is possible to receive television broadcasts by wired or wireless via a modem. By connecting to a communication network, it is possible to communicate in one direction (from sender to receiver) or two directions ( It is also possible to communicate information between a sender and a receiver, or between receivers.

[0155] FIG. 5B shows a computer, which includes a main body 7201, a housing 7202, a display unit 7203, and a keyboard. keyboard 7204, external connection port 7205, pointing device 7206, etc. Note that the computer is manufactured by using a light-emitting device for the display portion 7203. .

[0156] FIG. 5C shows a portable gaming machine, which is composed of two housings, a housing 7301 and a housing 7302. The housing 7301 is connected to the display unit 7301 by a connecting portion 7303 so as to be openable and closable. A display unit 7305 is incorporated in the housing 7302. The portable gaming machine shown in FIG. 5(C) also includes a speaker unit 7306, a recording medium insertion unit 7307, , LED lamp 7308, input means (operation keys 7309, connection terminal 7310, sensor 73 11 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical Chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration , including the function of measuring odor or infrared rays), microphone 7312) Of course, the configuration of the portable gaming machine is not limited to the above, and at least the display unit 73 04 and the display portion 7305, or both, may use a light-emitting device. The portable gaming machine shown in FIG. The function of reading out the program or data recorded on the media and displaying it on the display unit, and other It has the function of sharing information with the portable gaming machine by wireless communication. The functions of the portable gaming machine are not limited to these, and the portable gaming machine may have a variety of functions.

[0157] FIG. 5D shows an example of a mobile phone. The mobile phone 7400 has a housing 7401. In addition to the display unit 7402 incorporated in the The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, and the like. The device is used in the display portion 7402 .

[0158] In a mobile phone 7400 shown in FIG. 5D, information can be displayed by touching the display portion 7402 with a finger or the like. You can also make calls, write emails, and perform other operations. This can be done by touching the display portion 7402 with a finger or the like.

[0159] The screen of the display unit 7402 has three main modes. The first is a mode that mainly displays images. The first mode is a display mode, and the second mode is an input mode that mainly inputs information such as characters. This is a display + input mode that combines the display mode and the input mode.

[0160] For example, when making a call or creating an email, the display portion 7402 is used for inputting characters. In this case, you can input characters displayed on the screen. In this case, it is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402. I wish.

[0161] In addition, the mobile phone 7400 includes a sensor for detecting tilt, such as a gyro or an acceleration sensor. By providing a detection device having the above, the orientation of the mobile phone 7400 (portrait or landscape) can be determined, The screen display on the display portion 7402 can be automatically switched.

[0162] The screen mode can be switched by touching the display portion 7402 or operating the housing 7401. The type of image displayed on the display unit 7402 can be selected by operating the create button 7403. For example, the image signal to be displayed on the display unit can be switched by If the data is text data, the mode switches to display mode, and if the data is text data, the mode switches to input mode.

[0163] In the input mode, a signal detected by the optical sensor of the display unit 7402 is detected and displayed. If there is no input by touch operation on the display unit 7402 for a certain period of time, the screen mode is changed to the input mode. Alternatively, the display mode may be switched from the normal mode to the display mode.

[0164] The display portion 7402 can also function as an image sensor. By touching 402 with the palm or fingers and capturing an image of the palm print, fingerprint, etc., personal authentication can be performed. In addition, a backlight that emits near-infrared light to the display unit or a sensing light that emits near-infrared light By using a source, it is also possible to image finger veins, palm veins, etc.

[0165] FIG. 5(E) shows a tabletop lighting device, which includes a lighting unit 7501, a shade 7502, and an adjustable arm 7503. , a support 7504, a base 7505, and a power supply 7506. It is manufactured by using it for the lighting part 7501. The lighting device is a ceiling-mounted lighting device. This also includes wall-mounted or ceiling-mounted lighting fixtures.

[0166] Note that the structure shown in this embodiment mode may be combined as appropriate with structures shown in other embodiment modes or examples. It can be adjusted. [Example]

[0167] In this example, a 9- [4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation :CzPA) and the host material of the phosphorescent element (the first electron transporting material and the second electron transporting material 2-[3'-(dibenzothiophen-4-yl)biphenyl]- ... nyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II The triplet excitation energy level (T1 level) of the material used in this example was measured. The chemical formula of the material is shown below.

[0168] [ka]

[0169] The T1 level was measured by measuring the phosphorescence of each substance. The measurements were performed at a temperature of 10 K, irradiating each substance with 325 nm excitation light. For TBPDBq-II, time-resolved measurements were performed using a mechanical chopper. For PA, time-resolved measurements are difficult, so Ir(ppy)3 is added as a sensitizer. The measurement was carried out without time resolution. The measurement conditions were a weight ratio of CzPA to Ir(ppy)3 was added at a ratio of 1. The triplet excitation energy level was measured by Calculation from the absorption wavelength is more accurate than calculation from the light wavelength. However, the absorption of the T1 level is extremely Since the emission wavelength is very weak and difficult to measure, we will measure the T Therefore, the measured values ​​may contain some error. The measurement results are shown in Table 1. As shown in the figure.

[0170] [Table 1]

[0171] As shown in Table 1, the triplet excitation energy of CzPA that can be used as an electron transport layer is The electron transport level of the host material of the phosphorescent device (the first electron transport material and the second electron transport material) ) can be used as a triplet excited energy level of 2mDBTBPDBq-II. It was confirmed that the electron density was 0.69 eV lower than that of the conventional method. [Example]

[0172] In this example, light-emitting elements (light-emitting element 1, light-emitting element 3, and light-emitting element 5) according to one embodiment of the present invention were ), and comparative light-emitting elements (comparative light-emitting element 2, comparative light-emitting element 4, and comparative light-emitting element 6). The chemical formulas of the materials used in this example are shown below. vinegar.

[0173] [ka]

[0174] [ka]

[0175] The light-emitting elements of one embodiment of the present invention used in this example (Light-emitting Elements 1, 3, and Light-emitting element 5), and comparative light-emitting elements (comparative light-emitting element 2, comparative light-emitting element 4, and comparative light-emitting element 5). The method for fabricating element 6) is shown below.

[0176] The light-emitting element 1 and the comparative light-emitting element 2 are light-emitting elements that emit red light. Light-emitting element 3 and comparative light-emitting element 4 are light-emitting elements that emit green light, and light-emitting element 5 and comparative light-emitting element The element 6 is a light emitting element that emits blue light.

[0177] (Light-emitting element 1) First, on the substrate 1100, indium oxide-tin oxide containing silicon or silicon oxide is formed. A compound (ITO-SiO2, hereafter abbreviated as ITSO) was formed into a film by sputtering. The anode 1101 was formed. The composition of the target used was In2O3:SnO2: The SiO2 content was 85:10:5 [wt %]. The thickness of the anode 1101 was 110 nm. The electrode area was set to 2 mm x 2 mm.

[0178] Next, as a pretreatment for forming a light emitting element on the substrate 1100, the substrate surface is washed with water. After baking at 200°C for 1 hour, UV ozone treatment was performed for 370 seconds.

[0179] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170° C. for 30 minutes in the heating chamber of the deposition apparatus, the substrate 1100 It was left to cool for about 30 minutes.

[0180] Next, the substrate on which the anode 1101 is formed is placed so that the surface on which the anode 1101 is formed faces downward. The plate 1100 was fixed to a substrate holder provided in a vacuum deposition apparatus, and 10 -4 Up to Pa After reducing the pressure, 4,4',4''-( Benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-I I) The hole injection layer 1111 was formed by co-evaporating SiO 2 and molybdenum oxide. The weight ratio of DBT3P-II to molybdenum oxide was 4:2 (=DBT3 P-II: molybdenum oxide). This is a deposition method in which deposition is carried out simultaneously from multiple evaporation sources within a single chamber.

[0181] Next, 4-phenyl-4'-(9-phenylfluorene-9 -yl)triphenylamine (abbreviation: BPAFLP) to a thickness of 20 nm. Thus, a hole transport layer 1113 was formed.

[0182] Next, 2mDBTBPDBq-II and 4,4'-di(1-naphthyl)-4''-(9 -phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB) ) and (dipivaloylmethanato)bis(2,3,5-triphenylpyrazinato)iridiu Ir(tppr)2dpm) and Zn(III) were co-evaporated to form a hole transport layer 1113 An emitting layer 1115 was formed on the substrate. and Ir(tppr)2dpm weight ratio was 0.8:0.2:0.06 (=2mDBTB PDBq-II: PCBNBB: Ir(tppr) 2dpm). The thickness of the light-emitting layer 1115 was set to 40 nm.

[0183] In the light-emitting layer 1115, 2mDBTBPDBq-II is an electron transport material. PCBNBB is a hole transport material and acts as a host material. Ir(tppr)2dpm also functions as an organic material containing iridium. It is a complex and functions as a guest material.

[0184] Furthermore, a film of CzPA was formed on the light-emitting layer 1115 to a thickness of 10 nm, and an electron transport layer 1117 was formed.

[0185] Then, bathophenanthroline (abbreviation: BPhen) was deposited on the electron transport layer 1117 to a thickness of 1 The film was formed to a thickness of 5 nm to form a first electron injection layer 1119a.

[0186] Furthermore, lithium fluoride (LiF) was deposited on the first electron injection layer 1119a to a thickness of 1 nm. The second electron injection layer 1119b was formed by vapor deposition of a compound.

[0187] Finally, a cathode 1103 was formed on the second electron injection layer 1119b by depositing aluminum at 200 The light-emitting element 1 of this example was fabricated by vapor deposition to a film thickness of 100 nm.

[0188] (Comparative light-emitting element 2) The comparative light-emitting element 2 is different from the light-emitting element 1 in the electron transport layer 1117. Specifically, The electron transport layer 1117 of the light-emitting element 2 was made of 2mD instead of CzPA used in the light-emitting element 1. The thickness of the 2mDBTBPDBq-II film was 10 nm. did.

[0189] The comparative light-emitting element 2 has the same configuration as the light-emitting element 1 except for the electron transport layer 1117. It was made for you.

[0190] (Light-emitting element 3) The light-emitting element 3 is different from the light-emitting element 1 in the light-emitting layer 1115. Specifically, the light-emitting element 3 The light-emitting layer 1115 is made of 2mDBTBPDBq-II, PCBNBB, and Ir(tppr)2dpm instead of 2mDBTBPDBq-II, PCBNBB , and (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinate) ) Iridium(III) (abbreviation: Ir(tBuppm)2(acac)) was used.

[0191] The light-emitting layer 1115 of the light-emitting element 3 is made of 2mDBTBPDBq-II and PCBNBB. and Ir(tBuppm)2(acac) were co-evaporated. The weight ratio of BPDBq-II, PCBNBB, and Ir(tBuppm)2(acac) is , 0.8:0.2:0.06(=2mDBTBPDBq-II:PCBNBB:Ir(t The light-emitting layer 111 of the light-emitting element 3 was adjusted to have a thickness of 100 Å. The film thickness of 5 was set to 40 nm.

[0192] In the light-emitting layer 1115 of the light-emitting element 3, 2mDBTBPDBq-II acts as an electron transport PCBNBB is a hole transport material and functions as a host material. It functions as an assist material. It is an organometallic complex containing lithium and functions as a guest material.

[0193] The light-emitting element 3 was fabricated in the same manner as the light-emitting element 1 except for the light-emitting layer 1115. did.

[0194] (Comparative light-emitting element 4) The comparative light-emitting element 4 differs from the light-emitting element 1 in the light-emitting layer 1115 and the electron-transporting layer 1117. Specifically, the light-emitting layer 1115 of the comparative light-emitting element 4 is made of the same 2mDBTB as that used in the light-emitting element 1. 2mDBT instead of PDBq-II, PCBNBB, and Ir(tppr)2dpm BPDBq-II, PCBNBB, and Ir(tBuppm)2(acac) were used. In addition, the electron transport layer 1117 of the comparative light-emitting element 4 was formed using a compound other than CzPA used in the light-emitting element 1. , 2mDBTBPDBq-II was used.

[0195] The light-emitting layer 1115 of the comparative light-emitting element 4 was made of 2mDBTBPDBq-II and PCBN BB and Ir(tBuppm)2(acac) were co-evaporated. Weights of BTBPDBq-II, PCBNBB, and Ir(tBuppm)2(acac) The ratio was 0.8:0.2:0.06 (=2mDBTBPDBq-II:PCBNBB:Ir (tBuppm)2(acac)). The thickness of the layer 1115 was set to 40 nm.

[0196] The thickness of the electron transport layer 1117 of the comparative light-emitting element 4 was set to 10 nm.

[0197] The comparative light-emitting element 4 has the same structure as the light-emitting layer 1115 and the electron transport layer 1117. was fabricated in the same manner as in the light-emitting element 1.

[0198] (Light-emitting element 5) The light-emitting element 5 is different from the light-emitting element 1 in the light-emitting layer 1115. Specifically, the light-emitting element 5 The light-emitting layer 1115 is made of 2mDBTBPDBq-II, PCBNBB, and Ir(tppr)2dpm instead of CzPA and N,N'-bis(3-methyl phenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl] The compound used was [[1,6mMemFLPAPrn]]-pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn).

[0199] The light-emitting layer 1115 of the light-emitting element 5 is a compound containing CzPA and 1,6mMemFLPAPrn. The weight ratio of CzPA and 1,6mMemFLPAPrn was was adjusted to 1:0.05 (=CzPA:1,6mMemFLPAPrn). The thickness of the light-emitting layer 1115 of the light-emitting element 5 was set to 25 nm.

[0200] In the light-emitting layer 1115 of the light-emitting element 5, CzPA is an electron transporting material. 1,6mMemFLPAPrn also functions as a fluorescent material. It functions as a guest material.

[0201] The light-emitting element 5 was fabricated in the same manner as the light-emitting element 1 except for the light-emitting layer 1115. did.

[0202] (Comparative light-emitting element 6) The comparative light-emitting element 6 differs from the light-emitting element 1 in the light-emitting layer 1115 and the electron-transporting layer 1117. Specifically, the light-emitting layer 1115 of the comparative light-emitting element 6 is made of the same 2mDBTB as that used in the light-emitting element 1. Instead of PDBq-II, PCBNBB, and Ir(tppr)2dpm, CzPA, and 1,6mMemFLPAPrn were used. In the light-emitting device 7, 2mDBTBPDBq-II was used instead of CzPA used in the light-emitting device 1.

[0203] The light-emitting layer 1115 of the comparative light-emitting element 6 contains CzPA and 1,6mMemFLPAPr n and 1,6mMemFLPAPrn were co-evaporated. The ratio was adjusted to 1:0.05 (=CzPA:1,6mMemFLPAPrn). The thickness of the light-emitting layer 1115 of the comparative light-emitting element 6 was set to 25 nm.

[0204] In the light-emitting layer 1115 of the comparative light-emitting element 6, CzPA is an electron transporting material. 1,6mMemFLPAPrn functions as a host material. It functions as a guest material.

[0205] The thickness of the electron transport layer 1117 of the comparative light-emitting element 6 was set to 10 nm.

[0206] The comparative light-emitting element 6 has the same structure as the comparative light-emitting element 1115 except for the light-emitting layer 1115 and the electron-transporting layer 1117. was fabricated in the same manner as in the light-emitting element 1.

[0207] Furthermore, the light-emitting elements according to the above-described embodiments of the present invention (light-emitting element 1, light-emitting element 3, and light-emitting element 5) ), and comparative light-emitting elements (comparative light-emitting element 2, comparative light-emitting element 4, and comparative light-emitting element 6). The entire deposition process was carried out using a resistance heating method.

[0208] In this way, the light-emitting elements (light-emitting element 1, light-emitting element 3, and light-emitting element 5) according to one embodiment of the present invention , and the comparative light-emitting elements (comparative light-emitting element 2, comparative light-emitting element 4, and comparative light-emitting element 6) emit light. The configurations other than the layer 1115 and the electron transport layer 1117 are the same.

[0209] The light-emitting elements of one embodiment of the present invention obtained as described above (light-emitting element 1, light-emitting element 3, and light-emitting element and comparative light-emitting elements (comparative light-emitting element 2, comparative light-emitting element 4, and comparative light-emitting element 6). The device structure is shown in Table 2.

[0210] [Table 2]

[0211] As shown in Table 2, the light-emitting elements of one embodiment of the present invention contain phosphorescent materials (light-emitting elements 1 and 2). 2mDBTBPDBq-II was used as the host material for the fluorescent material (light-emitting element 5 CzPA was used as a host material for the light-emitting element 1, the light-emitting element 3, and the light-emitting element 4. The electron transport layer of the optical element 5 uses the same CzPA. 2mDBTBP was used as a host material for the phosphorescent materials (comparative light-emitting element 2 and comparative light-emitting element 4). DBq-II was used, and CzPA was used as the host material for the fluorescent material (comparative light-emitting element 6). In addition, the electron transport layer of the comparative light-emitting element 2, the comparative light-emitting element 4, and the comparative light-emitting element 6 , using the common 2mDBTBPDBq-II.

[0212] Next, each of the fabricated light-emitting devices was exposed to the atmosphere in a glove box with a nitrogen atmosphere. The process of sealing with a glass substrate to prevent the device from being damaged (sealing material is applied around the device and the device is sealed) Then, the device was subjected to a heat treatment at 80°C for 1 hour. After that, the operating characteristics of each light-emitting device were measured. The measurements were carried out at room temperature (an atmosphere maintained at 25°C).

[0213] FIG. 7 shows the current density-luminance characteristics of the light-emitting element 1 and the comparative light-emitting element 2, and FIG. 8 shows the voltage-luminance characteristics. The luminance-current efficiency characteristics are shown in Fig. 9, the voltage-current characteristics in Fig. 10, and the emission spectrum in Fig. 11. are shown below.

[0214] FIG. 12 shows the current density-luminance characteristics of the light-emitting element 3 and the comparative light-emitting element 4, and FIG. 13 shows the voltage-luminance characteristics of the light-emitting element 3 and the comparative light-emitting element 4. 13, the luminance-current efficiency characteristics are shown in Fig. 14, the voltage-current characteristics are shown in Fig. 15, and the emission spectrum is shown in Fig. 16. These are shown in FIG.

[0215] FIG. 17 shows the current density-luminance characteristics of the light-emitting element 5 and the comparative light-emitting element 6, and FIG. 18 shows the voltage-luminance characteristics of the light-emitting element 5 and the comparative light-emitting element 6. 18, the luminance-current efficiency characteristics are shown in Fig. 19, the voltage-current characteristics are shown in Fig. 20, and the emission spectrum is shown in Fig. These are shown in FIG.

[0216] 7, 12, and 17, the horizontal axis represents the current density (mA / cm 2 ) on the vertical axis is the luminance (cd / m 2 ) In addition, in Fig. 8, Fig. 13, and Fig. 18, the horizontal axis represents voltage ( V) and the vertical axis is luminance (cd / m 2 ) In addition, in Figs. 9, 14, and 19, The horizontal axis is luminance (cd / m 2 ), and the vertical axis represents the current efficiency (cd / A). 20, the horizontal axis represents voltage (V) and the vertical axis represents current (mA). 16 and 21, the horizontal axis represents wavelength (nm) and the vertical axis represents intensity (arbitrary unit). 11, 16, and 21, the emission spectra of the light-emitting elements are roughly overlapped. It is.

[0217] In addition, the luminance of each light-emitting element is 1000 cd / m 2 Voltage (V) and current density near (mA / cm 2 ), CIE chromaticity coordinates (x, y), current efficiency (cd / A), external quantum efficiency ( %) are shown in Table 3.

[0218] [Table 3]

[0219] As shown in Table 3, the luminance of light-emitting element 1 is 992 cd / m 2 The element characteristics in The luminance is 27 cd / A, the external quantum efficiency is 24%, and the CIE chromaticity coordinates are (x, y) =(0.66, 0.34). The luminance of the comparative light-emitting element 2 was 1103 cd / m2 oh The device characteristics are a current efficiency of 27 cd / A, an external quantum efficiency of 23%, and a C The IE chromaticity coordinates were (x,y)=(0.66,0.34).

[0220] As shown in FIG. 11, the emission spectra of the light-emitting element 1 and the comparative light-emitting element 2 are 619 It has a peak at 100 nm.

[0221] As described above, when comparing light-emitting element 1 and comparative light-emitting element 2, no significant differences were observed in the element characteristics. That is, the electron transporting property of the electron transporting layer 1117 (CzPA) of the light-emitting element 1 and The electron transport of the electron transport material (2mDBTBPDBq-II), which is the host material of the phosphorescent material, Since the transmittance is very high, the light emitted from the light-emitting layer 1115 diffuses to the electron transport layer 1117 side. It was confirmed that the element configuration does not cause diffusion or is difficult to cause diffusion.

[0222] Furthermore, as shown in Table 3, the luminance of light-emitting element 3 was 804 cd / m 2 The element characteristics are as follows: The current efficiency is 91 cd / A, the external quantum efficiency is 26%, and the CIE chromaticity coordinates are (x , y)=(0.43, 0.56). The luminance of the comparative light-emitting element 4 was 987 cd / m 2 The device characteristics are a current efficiency of 93 cd / A and an external quantum efficiency of 26%. The CIE chromaticity coordinates were (x,y)=(0.43,0.56).

[0223] As shown in FIG. 16, the emission spectra of the light-emitting element 3 and the comparative light-emitting element 4 are It has peaks at 549 nm and 546 nm.

[0224] As described above, when comparing light-emitting element 3 and comparative light-emitting element 4, no significant differences in the element characteristics were observed. That is, the electron transporting property of the electron transporting layer 1117 (CzPA) of the light-emitting element 3 and the phosphorus Electron transport in the electron transport material (2mDBTBPDBq-II) which is the host material for the photoactive material Since the conductivity is very high, the light emitted from the light-emitting layer 1115 is diffused to the electron transport layer 1117 side. It was confirmed that the element configuration was such that diffusion was not observed or was difficult to occur.

[0225] Furthermore, as shown in Table 3, the luminance of light-emitting element 5 was 905 cd / m 2 The element characteristics are as follows: The current efficiency is 11 cd / A, the external quantum efficiency is 9%, and the CIE chromaticity coordinates are (x, y)=(0.14, 0.19). The luminance of the comparative light-emitting element 6 was 1115 cd / m 2 The device characteristics are a current efficiency of 12 cd / A and an external quantum efficiency of 9%. The CIE chromaticity coordinates were (x,y)=(0.14,0.19).

[0226] As shown in FIG. 21, the emission spectra of the light-emitting element 5 and the comparative light-emitting element 6 are It has peaks at 464 nm and 465 nm.

[0227] As described above, when comparing the light-emitting element 5 and the comparative light-emitting element 6, there are differences in the element characteristics. Specifically, as shown in Table 3 and Figure 20, the main difference is in the voltage-current characteristics. Light-emitting element 5 is 905 cd / m 2 The voltage at 1 115cd / m 2 The voltage at this point is 3.5V. Also, as shown in Figure 20, the voltage at When the voltage was increased from 0.01 to 0.25 V, the current value of the comparative light-emitting element 6 was lower than that of the light-emitting element 5 of one embodiment of the present invention. .

[0228] This is because the electron transport layer 1117 of the comparative light-emitting element 6 is an electron transport layer that is a host material for the phosphorescent material. This is due to the use of a transport material (2mDBTBPDBq-II). The host material of the material is different from the electron transporting material (CzPA) used in the light-emitting layer 1115. As a result, the electron transport property is reduced.

[0229] On the other hand, in the light-emitting element 5 of one embodiment of the present invention, the electron-transporting property of the electron-transporting layer 1117 (CzPA) is However, the electron transport material (2mDBTBPDBq-II), which is the host material for the phosphorescent material, Since it has better electron transport properties than the other materials, it has excellent device characteristics at a lower driving voltage.

[0230] The configuration shown in this embodiment may be the same as the configuration shown in other embodiments or the configuration shown in other embodiments. It can be used in combination with other components as appropriate. [Example]

[0231] In this example, light-emitting elements (light-emitting elements 7 and 8) of one embodiment of the present invention are shown in FIG. 6(B) will be used for the explanation. The chemical formulas of the materials used in this example are shown below.

[0232] [ka]

[0233] [ka]

[0234] The light-emitting elements (light-emitting elements 7 and 8) of one embodiment of the present invention used in this example are described below. The manufacturing method is shown below.

[0235] The light-emitting element 7 is a light-emitting element that emits red light, and the light-emitting element 8 is a light-emitting element that emits green light. The light emitting element shown in FIG.

[0236] (Light emitting element 7) First, on the substrate 1100, indium oxide-tin oxide containing silicon or silicon oxide is formed. The compound (ITSO) was deposited by sputtering to form an anode 1101. The composition of the target used was In2O3:SnO2:SiO2 = 85:10:5 [wt%] The thickness of the anode 1101 was 110 nm, and the electrode area was 2 mm × 2 mm. Ta.

[0237] Next, as a pretreatment for forming a light emitting element on the substrate 1100, the substrate surface is washed with water. After baking at 200°C for 1 hour, UV ozone treatment was performed for 370 seconds.

[0238] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170° C. for 30 minutes in the heating chamber of the deposition apparatus, the substrate 1100 It was left to cool for about 30 minutes.

[0239] Next, the substrate on which the anode 1101 is formed is placed so that the surface on which the anode 1101 is formed faces downward. The plate 1100 was fixed to a substrate holder provided in a vacuum deposition apparatus, and 10 -4 Up to Pa After reducing the pressure, 4,4',4''-( Benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P- II) The hole injection layer 1111 was formed by co-evaporating SiO 2 and molybdenum oxide. The weight ratio of DBT3P-II to molybdenum oxide was 4:2 (=DBT3 P-II: molybdenum oxide).

[0240] Next, 4-phenyl-4'-(9-phenylfluorene-9 -yl)triphenylamine (abbreviation: BPAFLP) to a thickness of 20 nm. Thus, a hole transport layer 1113 was formed.

[0241] Next, 2mDBTBPDBq-II and 4,4'-di(1-naphthyl)-4''-(9 -phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB) ) and (dipivaloylmethanato)bis(2,3,5-triphenylpyrazinato)iridiu Ir(tppr)2dpm) and Zn(III) were co-evaporated to form a hole transport layer 1113 An emitting layer 1115 was formed on the substrate. and Ir(tppr)2dpm weight ratio was 0.8:0.2:0.06 (=2mDBTB PDBq-II: PCBNBB: Ir(tppr) 2dpm). The thickness of the light-emitting layer 1115 was set to 40 nm.

[0242] In the light-emitting layer 1115, 2mDBTBPDBq-II is an electron transport material. PCBNBB is a hole transport material and acts as a host material. Ir(tppr)2dpm also functions as an organic material containing iridium. It is a complex and functions as a guest material.

[0243] Furthermore, CzPA and 1,6mMemFLPAPrn are co-deposited on the light-emitting layer 1115. Then, an electron transport layer 1117a was formed on the light-emitting layer 1115. The weight ratio of CzPA to 6mMemFLPAPrn was 1:0.05 (= CzPA:1,6mMemFL The thickness of the electron transport layer 1117a of the light-emitting element 7 was adjusted to be PAPrn). The thickness was set to 25 nm.

[0244] The electron transport layer 1117a of the light-emitting element 7 was the same as that of the light-emitting element 5 shown in Example 2 and the comparative light-emitting element 6 shown in Example 3. The structure is the same as that used for the light-emitting layer of the light-emitting element 6. That is, the light-emitting layer that emits blue light is This is a configuration used as the electron transport layer 1117a of the optical element 7.

[0245] Then, bathophenanthroline (abbreviation: BPhen) was deposited on the electron transport layer 1117 to a thickness of 1 The film was formed to a thickness of 5 nm to form a first electron injection layer 1119a.

[0246] Furthermore, lithium fluoride (LiF) was deposited on the first electron injection layer 1119a to a thickness of 1 nm. The second electron injection layer 1119b was formed by vapor deposition of a compound.

[0247] Finally, a cathode 1103 was formed on the second electron injection layer 1119b by depositing aluminum at 200 The light-emitting element 7 of this example was fabricated by vapor deposition to a film thickness of 100 nm.

[0248] (Light emitting element 8) The light-emitting element 8 is different from the light-emitting element 7 in the light-emitting layer 1115. Specifically, the light-emitting element 8 The light-emitting layer 1115 is made of 2mDBTBPDBq-II, PCBNBB, and Ir(tppr)2dpm instead of 2mDBTBPDBq-II, PCBNBB , and Ir(tBuppm)2(acac) were used.

[0249] The light-emitting layer 1115 of the light-emitting element 8 is made of 2mDBTBPDBq-II and PCBNBB and Ir(tBuppm)2(acac) are co-evaporated to form a hole transport layer 1113. Here, 2mDBTBPDBq-II, PCBNBB, and Ir(tBuppm) The weight ratio of 2(acac) was 0.8:0.2:0.06 (=2mDBTBPDBq-II :PCBNBB:Ir(tBuppm)2(acac)). The thickness of the light-emitting layer 1115 of the light-emitting element 8 was set to 40 nm.

[0250] In the light-emitting layer 1115 of the light-emitting element 8, 2mDBTBPDBq-II was an electron transport PCBNBB is a hole transport material and functions as a host material. It functions as an assist material. It is an organometallic complex containing lithium and functions as a guest material.

[0251] The electron transport layer 1117a of the light-emitting element 8 is the same as that of the light-emitting element 7, as shown in Example 2. The structure is the same as that used in the light-emitting layer of the light-emitting element 5 and the comparative light-emitting element 6. The light-emitting layer that emits light is used as the electron transport layer 1117 a of the light-emitting element 8 .

[0252] The light-emitting element 8 was fabricated in the same manner as the light-emitting element 7 except for the light-emitting layer 1115. did.

[0253] The deposition process of the light-emitting elements (light-emitting elements 7 and 8) according to one embodiment of the present invention is as follows: All of these were done using a resistance heating method.

[0254] The element structures of the light-emitting elements (light-emitting elements 7 and 8) according to one embodiment of the present invention obtained as described above were The structure is shown in Table 4.

[0255] [Table 4]

[0256] As shown in Table 4, the light-emitting elements of one embodiment of the present invention contain phosphorescent materials (light-emitting elements 7 and 8). 8) 2mDBTBPDBq-II is used as the host material. The electron transport layer of the light-emitting element 8 uses the same CzPA and 1,6mMemFLPAPrn. It is.

[0257] Next, each of the fabricated light-emitting devices was exposed to the atmosphere in a glove box with a nitrogen atmosphere. The process of sealing with a glass substrate to prevent the device from being damaged (sealing material is applied around the device and the device is sealed) Then, the device was subjected to a heat treatment at 80°C for 1 hour. After that, the operating characteristics of each light-emitting device were measured. The measurements were carried out at room temperature (an atmosphere maintained at 25°C).

[0258] FIG. 22 shows the current density-luminance characteristics of the light-emitting element 7 and the light-emitting element 8, and FIG. 23 shows the voltage-luminance characteristics of the light-emitting element 7 and the light-emitting element 8. The luminance-current efficiency characteristics are shown in Figure 24, the voltage-current characteristics in Figure 25, and the emission spectrum in Figure 26. 6, respectively.

[0259] In FIG. 22, the horizontal axis represents the current density (mA / cm 2 ) and the vertical axis is luminance (cd / m 2 ) In FIG. 23, the horizontal axis represents voltage (V) and the vertical axis represents luminance (cd / m 2 ) In Figure 24, the horizontal axis represents luminance (cd / m 2 ), and the vertical axis represents the current efficiency (cd / A). In FIG. 25, the horizontal axis represents voltage (V) and the vertical axis represents current (mA). In FIG. 26, the horizontal axis represents wavelength (nm) and the vertical axis represents intensity (arbitrary unit).

[0260] In addition, the luminance of each light-emitting element is 1000 cd / m 2 Voltage (V) and current density near (mA / cm 2 ), CIE chromaticity coordinates (x, y), current efficiency (cd / A), external quantum efficiency ( %) are shown in Table 5.

[0261] [Table 5]

[0262] As shown in Table 5, the luminance of light-emitting element 7 was 984 cd / m 2 The element characteristics in The luminance is 27 cd / A, the external quantum efficiency is 25%, and the CIE chromaticity coordinates are (x, y) =(0.66, 0.34). The luminance of light-emitting element 8 was 948 cd / m 2 O The characteristics are a current efficiency of 76 cd / A, an external quantum efficiency of 23%, and a CIE color The degree coordinates were (x,y)=(0.44,0.56).

[0263] As shown in FIG. 26, the emission spectra of the light-emitting elements 7 and 8 are 6 The peaks are at 20 nm and 548 nm. It can be seen that blue light emission from FLPAPrn (see FIG. 21) was not observed.

[0264] As described above, the light-emitting element 7 of one embodiment of the present invention contains a blue electron-transport layer 1117a. Even when a light-emitting layer that emits light was used, the same device characteristics as those of the light-emitting device 1 shown in Example 2 were obtained. Furthermore, the light-emitting element 8 of one embodiment of the present invention has an electron-transport layer 1117a that emits blue light. Even when the light-emitting layer was used, the same device characteristics as those of the light-emitting device 3 shown in Example 2 were obtained.

[0265] Therefore, the electron transport layer 1117a is formed by the electron transporting layer 1117b. The electron transport material (2mDBTBPDBq-I) is a host material for electron transport and phosphorescent materials. Since I) has a large electron transporting property, the light emitting region of this light emitting device is a hole transporting layer of the light emitting layer 1115. The light emitted by the light-emitting layer 1115 is emitted to the electron transport layer 1117. It was confirmed that the device structure does not or does not easily diffuse to the a-side. The electron transport layer 1117a used in the device 7 and the light-emitting device 8 contains 1.6 mM of a fluorescent material. However, as shown in Figures 22 to 26, It was confirmed that the active material 1,6mMemFLPAPrn does not affect the device characteristics. It was.

[0266] The configuration shown in this embodiment may be the same as the configuration shown in other embodiments or the configuration shown in other embodiments. It can be used in combination with other components as appropriate. [Example]

[0267] In this example, the light-emitting element of one embodiment of the present invention manufactured in Example 2 and Example 3 was The light-emitting element 1, the light-emitting element 3, the light-emitting element 7, and the light-emitting element 8, and the comparative light-emitting element A reliability test was carried out on the element 2 and the comparative light-emitting element 4. The results of the reliability test are shown in FIG. Shown in (A) and (B).

[0268] FIG. 27A shows the light-emitting element 1, the comparative light-emitting element 2, and the light-emitting element 7, i.e., the red element. 27B shows the reliability test results of the light-emitting element 3, the comparative light-emitting element 4, and the These are the reliability test results for optical element 8, i.e., the green element. The reliability test is performed with an initial brightness of 5000 cd / m 2 and the current density is set to Each light-emitting element was driven under the same conditions. The horizontal axis represents the driving time (h) of the element, and the vertical axis represents the initial luminance (1 27(A) and (B), the normalized brightness (%) is shown when the brightness is 0.0 ... The data for the optical elements are roughly overlapping.

[0269] From the results of FIG. 27(A), the normalized luminance of the light-emitting element 1 after 357 hours was 68%. The normalized luminance of the comparative light-emitting element 2 after 357 hours was 68%. The normalized luminance of the light-emitting element 7 after 357 hours was 66%. As a result, the normalized luminance of the light-emitting element 3 after 688 hours was 81%. The normalized luminance of the comparative light-emitting element 4 after 688 hours was 82%. After 688 hours, the normalized luminance was 80%.

[0270] As described above, the light-emitting element 1 and the light-emitting element 7, which are embodiments of the present invention, are similar to the comparative light-emitting element 2. The reliability test results were similar. The reliability test results for the comparative light-emitting element 8 were the same as those for the comparative light-emitting element 4.

[0271] The configuration shown in this embodiment may be the same as the configuration shown in other embodiments or the configuration shown in other embodiments. It can be used in combination with other components as appropriate. [Explanation of symbols]

[0272] 100 boards 101 Anode 103 Cathode 111 Hole injection layer 113 Hole transport layer 113a First hole transport layer 113b Second hole transport layer 113c Third hole transport layer 113d Fourth hole transport layer 115 Light-emitting layer 115a First light-emitting layer 115b Second light-emitting layer 115c Third light-emitting layer 117 Electron transport layer 119 Electron injection layer 121a First phosphorescent material 122a First electron transport material 123a First hole transport material 131a Second phosphorescent material 132a Second electron transport material 133a Second hole transport material 141a Fluorescent materials 142a Third electron transport material 200 boards 201a Anode 201b Anode 201c anode 203 Cathode 211 Hole injection layer 213a First hole transport layer 213b Second hole transport layer 213c Third hole transport layer 215a First light-emitting layer 215b Second light-emitting layer 215c Third luminescent layer 217 Electron transport layer 219 Electron injection layer 250 Light-emitting device 251a Bulkhead 251b Bulkhead 251c Bulkhead 251d Bulkhead 253 Semi-transparent / semi-reflective electrode 253a reflective electrode 253b reflective electrode 253c reflective electrode 260 Light-emitting device 1100 board 1101 Anode 1103 Cathode 1111 Hole injection layer 1113 Hole transport layer 1115 Light-emitting layer 1117 Electron transport layer 1117a Electron transport layer 1119a Electron injection layer 1119b Electron injection layer 7100 Television equipment 7101 Housing 7103 Display section 7105 Stand 7107 Display section 7109 Operation key 7110 Remote control device 7201 Main unit 7202 Case 7203 Display section 7204 keyboard 7205 External connection port 7206 Pointing Device 7301 Housing 7302 Housing 7303 Connection section 7304 Display section 7305 Display section 7306 Speaker section 7307 Recording medium insertion section 7308 LED Lamp 7309 Operation Key 7310 Connection terminal 7311 Sensor 7312 Microphone 7400 mobile phone 7401 Housing 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7501 Lighting Department 7502 umbrella 7503 Adjustable Arm 7504 Post 7505 units 7506 Power supply

Claims

1. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

2. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

3. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption band on the longest wavelength side of an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

4. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

5. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

6. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption band on the longest wavelength side of an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

7. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

8. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

9. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption band on the longest wavelength side of an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

10. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

11. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

12. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the nitrogen-containing heteroaromatic compound contained in the first light-emitting layer and the compound having a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption band on the longest wavelength side of an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

13. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

14. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

15. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption band on the longest wavelength side of an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

16. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

17. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

18. A light-emitting device having a light-emitting element that emits green light, a light-emitting element that emits blue light, and a light-emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption band on the longest wavelength side of an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

19. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

20. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

21. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption band on the longest wavelength side of an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

22. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

23. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

24. A light emitting device having a top emission structure, the light emitting device having a light emitting element that emits green light, a light emitting element that emits blue light, and a light emitting element that emits red light, the green light-emitting element includes a first light-emitting layer and a first electron transport layer that is in contact with a cathode side of the first light-emitting layer and that includes a first compound; the blue light-emitting element includes a second light-emitting layer and a second electron transport layer that is in contact with a cathode side of the second light-emitting layer and includes the first compound; the red light-emitting element includes a third light-emitting layer and a third electron transport layer that is in contact with a cathode side of the third light-emitting layer and includes the first compound; the π-electron-deficient heteroaromatic compound contained in the first light-emitting layer and the compound containing a carbazole skeleton contained in the first light-emitting layer are a combination that forms an exciplex, an emission spectrum of the exciplex overlaps with an absorption band on the longest wavelength side of an absorption spectrum of a light-emitting substance contained in the first light-emitting layer; the first electron transport layer, the second electron transport layer, and the third electron transport layer are used as a common electron transport layer in the light-emitting element that exhibits green light emission, the light-emitting element that exhibits blue light emission, and the light-emitting element that exhibits red light emission; a triplet excitation energy level of the first compound is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

25. In any one of claims 1 to 12, a triplet excitation energy level of the organic compound containing an anthracene skeleton in the second light-emitting layer that is lower than a triplet excitation energy level of the nitrogen-containing heteroaromatic compound;

26. In any one of claims 13 to 24, a triplet excitation energy level of the organic compound containing an anthracene skeleton in the second light-emitting layer that is lower than a triplet excitation energy level of the π-electron-deficient heteroaromatic compound;

27. In claim 25 or claim 26, The triplet excitation energy level of the organic compound containing the anthracene skeleton in the second light-emitting layer is Ir(ppy) ３ The light-emitting device was obtained by adding

28. In any one of claims 2, 3, 5, 6, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21, 23 and 24, A light-emitting device, wherein the peak of the emission spectrum of the exciplex is at a wavelength longer than the peak of the absorption spectrum of the luminescent substance.

29. In any one of claims 2, 3, 5, 6, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21, 23, 24 and 28, The light-emitting device, wherein the luminescent material contains iridium and has an emission peak in the range of 520 nm to 600 nm.

30. In any one of claims 1 to 29, The light-emitting device, wherein the first compound includes an anthracene skeleton.

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