Light-emitting element, light-emitting device, electronic apparatus, and illumination device

Abstract

To provide a light-emitting element having improved reliability, a light-emitting element having high current efficiency (or, quantum efficiency), and a new dibenzo [f,h] quinoxaline derivative suitable for application to a light-emitting element, in one aspect of the present invention.SOLUTION: A light-emitting element includes an EL layer between a positive electrode and a negative electrode, the EL layer including a light-emitting layer, the light-emitting layer including a first organic compound having an electron transport property and hole transport property, a second organic compound having a hole transport property, and a light-emitting material. A combination of the first organic compound and the second organic compound forms an excited complex. The first organic compound's HOMO level is lower than the second organic compound's HOMO level. A difference between the first organic compound's HOMO level and the second organic compound's HOMO level is equal to or smaller than 0.4 eV.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an article, a method, or a manufacturing method. , manufacture, or composition of matter. One embodiment of the present invention is a light-emitting element, a light-emitting device, an electronic device, a lighting device, and a driving method thereof. The present invention also relates to a light-emitting element, a light-emitting device, an electronic device, and a method for manufacturing the same. The present invention relates to organic compounds that can be used in lighting devices. [Background technology]

[0002] The organic compound used as the light emitter has characteristics such as being thin and lightweight, having high-speed response, and being driven by a low direct current voltage. The light-emitting element is expected to be applied to the next generation of flat panel displays. A display device in which light-emitting elements are arranged in a matrix has a longer viewing angle than a conventional liquid crystal display device. It is believed that its advantages lie in its wide corners and excellent visibility.

[0003] The mechanism of light emission of a light-emitting element is to sandwich an EL 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 regenerated at the luminescence centers of the EL layer. They combine to form molecular excitons, which release energy as they relax to the ground state. It is said that they emit light by releasing the light. There are two types of excited states: singlet excitation and triplet excitation. It is believed that either excited state is possible.

[0004] Regarding such light-emitting devices, in order to improve the device characteristics, improvements in the device structure and material development have been carried out. Developments in this field are being actively pursued (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-182699 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the development of light-emitting devices, increasing the reliability of the devices is an important factor for commercialization. In order to improve the reliability of the element, the capacitance of the EL layer of the light-emitting element is A device configuration that allows control of rear balance and improves the probability of carrier recombination is required. Therefore, by forming the EL layer into a desired device configuration, carrier movement in the light-emitting layer can be improved. In addition, it is an object of the present invention to provide a light-emitting element having high current efficiency (or It is also important to obtain a high quantum efficiency in order to reduce the amount of current required for driving and to improve reliability. .

[0007] In view of this, one embodiment of the present invention provides a light-emitting element with improved reliability. Further, a light-emitting element according to one embodiment of the present invention is provided. In another aspect of the present invention, a novel organic compound is provided, which is preferably applied to the above-mentioned Light emitting element and light emitting device with high luminous efficiency and high reliability using the organic compound as an EL material In another aspect of the present invention, a novel material is provided. Another embodiment of the present invention provides a novel light-emitting element and a novel light-emitting device. The description of these problems does not preclude the existence of other problems. It is not necessary for the embodiment to solve all of these problems. The above will become apparent from the description in the specification, drawings, claims, etc. It is possible to extract other issues from the descriptions in the patent, claims, etc. [Means for solving the problem]

[0008] One embodiment of the present invention is a device having an EL layer between an anode and a cathode, the EL layer having a light-emitting layer, The optical layer includes a first organic compound having an electron transport property and a hole transport property, and a second organic compound having a hole transport property. The organic light-emitting device includes a second organic compound and a light-emitting material, and the first organic compound and the second organic compound are an excitation light-emitting material. The HOMO level of the first organic compound is higher than that of the second organic compound. The HOMO level of the first organic compound is lower than the HOMO level of the second organic compound. The light-emitting element is characterized in that the difference between the HOMO level of

[0009] In addition, another embodiment of the present invention is a light-emitting device having an EL layer between an anode and a cathode. The light-emitting layer comprises a first organic compound having an electron transport property and a hole transport property, and a second organic compound having a hole transport property. The first organic compound and the second organic compound have a property of being luminescent, and the first organic compound and the second organic compound have a property of being luminescent, The compound is a combination that forms an exciplex, and the first organic compound is a six-membered nitrogen-containing complex. a first aromatic ring and a carbazole skeleton, and a second aromatic ring and a carbazole skeleton, but not a triarylamine skeleton; The organic compound is a light-emitting element characterized by including a triarylamine skeleton.

[0010] In addition, another embodiment of the present invention is a light-emitting device having an EL layer between an anode and a cathode. The light-emitting layer comprises a first organic compound having an electron transport property and a hole transport property, and a second organic compound having a hole transport property. The first organic compound and the second organic compound have a property of being luminescent, and the first organic compound and the second organic compound have a property of being luminescent, The compound is a combination that forms an exciplex, and the first organic compound is composed of a six-membered ring. The compound contains a nitrogen-containing heteroaromatic ring and a bicarbazole skeleton, and also contains a triarylamine skeleton. First, the second organic compound is a light-emitting element that includes a triarylamine skeleton. do.

[0011] In the above structure, the bicarbazole skeleton is a 3,3'-bicarbazole skeleton, or is characterized by having a 2,3'-bicarbazole skeleton.

[0012] In each of the above structures, the light-emitting substance is a phosphorescent compound.

[0013] In each of the above structures, the EL layer includes a hole transport layer, and the hole transport layer and the light emitting layer are mutually The hole transport layer has a third organic compound having a hole transport property. The HOMO level of the light-emitting element is lower than the HOMO level of the second organic compound. It is.

[0014] In each of the above structures, the first organic compound is represented by the following general formula (G0): The light emitting device is characterized by the above.

[0015] [ka]

[0016] In the formula, A represents a dibenzo[f,h]quinoxalinyl group, R 1 ~R 15 Is that each independently represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, Substituted cycloalkyl group having 5 to 7 carbon atoms, substituted or unsubstituted aryl group having 6 to 13 carbon atoms Ar represents a substituted or unsubstituted arylene group having 6 to 25 carbon atoms; or a single bond. Note that the arylene group of Ar does not include an anthracenylene group. It is preferable.

[0017] Another embodiment of the present invention is an organic compound represented by the following general formula (G0).

[0018] [ka]

[0019] In the formula, A represents a dibenzo[f,h]quinoxalinyl group, R 1 ~R 15 Is that each independently represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, Substituted cycloalkyl group having 5 to 7 carbon atoms, substituted or unsubstituted aryl group having 6 to 13 carbon atoms Ar represents a substituted or unsubstituted arylene group having 6 to 25 carbon atoms; or a single bond. Note that the arylene group of Ar does not include an anthracenylene group. It is preferable.

[0020] Another embodiment of the present invention is an organic compound represented by the following general formula (G1).

[0021] [ka]

[0022] In the formula, R 1 ~R 24 are each independently hydrogen or a substituted or unsubstituted group having 1 to 1 6 alkyl group, substituted or unsubstituted cycloalkyl group having 5 to 7 carbon atoms, substituted or or an unsubstituted aryl group having 6 to 13 carbon atoms, Ar is an arylene group having 6 to 25 carbon atoms, or a single bond. It is therefore preferred that the aryl group does not contain an anthracenylene group.

[0023] Another embodiment of the present invention is an organic compound represented by the following general formula (G2).

[0024] [ka]

[0025] In the formula, R 1 ~R 24 are each independently hydrogen or a substituted or unsubstituted group having 1 to 1 6 alkyl group, substituted or unsubstituted cycloalkyl group having 5 to 7 carbon atoms, substituted or or an unsubstituted aryl group having 6 to 13 carbon atoms, Ar is an arylene group having 6 to 25 carbon atoms, or a single bond. It is therefore preferred that the aryl group does not contain an anthracenylene group.

[0026] Another embodiment of the present invention is an organic compound represented by the following general formula (G3).

[0027] [ka]

[0028] In the formula, R 1 ~R 24 are each independently hydrogen or a substituted or unsubstituted group having 1 to 1 6 alkyl group, substituted or unsubstituted cycloalkyl group having 5 to 7 carbon atoms, substituted or or an unsubstituted aryl group having 6 to 13 carbon atoms, Ar is an arylene group having 6 to 25 carbon atoms, or a single bond. It is therefore preferred that the aryl group does not contain an anthracenylene group.

[0029] In addition, in the above-mentioned general formula (G0), general formula (G2) and general formula (G3), Examples of the alkyl group of 1 to 6 include a methyl group, an ethyl group, a propyl group, and an isopropyl group. , butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, iso Examples of the cycloalkyl group having 5 to 7 carbon atoms include pentyl and hexyl groups. Examples of the aryl group include a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. Examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a tolyl group, and a xylyl group. , biphenyl group, indenyl group, naphthyl group, fluorenyl group, etc. The arylene group having 6 to 25 carbon atoms in Ar is 1,2-, 1,3- or 1 ,4-phenylene group, 2,6- or 3,5- or 2,4-toluylene group, 4,6-di Methylbenzene-1,3-diyl group, 2,4,6-trimethylbenzene-1,3-diyl group, 2,3,5,6-tetramethylbenzene-1,4-diyl group, 3,3'- or 3, 4'- or 4,4'-biphenylene group, 1,1':3',1''-tert-benzene-3, 3''-diyl group, 1,1':4',1''-tert-benzene-3,3''-diyl group, 1 ,1':4',1''-tert-4,4''-diyl group, 1,1':3',1'' :3'',1'''-quaterbenzene-3,3'''-diyl group, 1,1':3',1 '':4'',1'''-quaterbenzene-3,4'''-diyl group, 1,1':4' ,1'':4'',1'''-quaterbenzene-4,4'''-diyl group, 1,4- or a 1,5-, 2,6- or 2,7-naphthylene group, a 2,7-fluorenylene group, 9,9-Dimethyl-2,7-fluorenylene group, 9,9-diphenyl-2,7-fluorene group 9,9-dimethyl-1,4-fluorenylene group, spiro-9,9'-bifluorenylene group 9,10-dihydro-2,7-phenanthrenylene group, 2,7 -Phenanthrenylene group, 3,6-phenanthrenylene group, 9,10-phenanthrenylene group 2,7-triphenylene group, 3,6-triphenylene group, 2,8-benzo [a]phenanthrenylene group, 2,9-benzo[a]phenanthrenylene group, 5,8-benzo[a]phenanthrenylene group and benzo[c]phenanthrenylene groups.

[0030] In addition, the above-mentioned alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups having 5 to 7 carbon atoms, and alkyl groups having 6 The aryl group having from 1 to 13 carbon atoms and the arylene group having from 6 to 25 carbon atoms may have a substituent. The substituents include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, butyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl C1-6 alkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl groups. Cycloalkyl groups having 5 to 7 carbon atoms, such as ethyl groups, phenyl groups, tolyl groups, xylyl groups, biphenyl groups, Phenyl group, indenyl group, naphthyl group, fluorenyl group, 9,9'-dimethylfluorene group An aryl group having 6 to 13 carbon atoms forming a ring, such as an aryl group, is preferred.

[0031] Another aspect of the present invention is a method for producing an organic compound represented by any one of the general formulae (G0) to (G3). This is the light-emitting element used.

[0032] Another embodiment of the present invention is a light-emitting device including the light-emitting element having any of the above structures and a housing. be.

[0033] Note that one embodiment of the present invention is not only a light-emitting device having a light-emitting element, but also a light-emitting element or a light-emitting device Electronic equipment to which the device is applied (specifically, the light-emitting element or the light-emitting device and a connection terminal or an operating and a lighting device (specifically, a light-emitting element or a light-emitting device and a housing Therefore, the light-emitting device in this specification also includes a lighting device having a light-emitting body. The term "device" refers to an image display device or a light source (including lighting equipment). Connectors, such as FPC (Flexible printed circuit) or is a module equipped with a TCP (Tape Carrier Package), A module with a printed wiring board at the end of the TCP, or a light-emitting element with COG (Chi All modules with ICs directly mounted using the PO On Glass method are also This is included in the light-emitting device. Effect of the Invention

[0034] According to one aspect of the present invention, it is possible to provide novel dibenzo[f,h]quinoxaline derivatives. According to one aspect of the present invention, the dibenzo[f,h]quinoxaline derivative can be prepared by the method of The present invention relates to a light-emitting element, a light-emitting device, an electronic device, and an optical material having high luminous efficiency and high reliability. According to one embodiment of the present invention, a novel material can be provided. In another embodiment of the present invention, a novel light-emitting element and a light-emitting device are provided. The description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Effects other than these will become apparent from the description, drawings, claims, etc. It is possible to extract other effects from the description, drawings, claims, etc. do. [Brief description of the drawings]

[0035] [Figure 1] 2A to 2C are diagrams illustrating a light-emitting layer of a light-emitting element. [Diagram 2] 2A to 2C are diagrams illustrating a light-emitting layer of a light-emitting element. [Diagram 3] 1A to 1C are diagrams illustrating a structure of a light-emitting element. [Figure 4] 1A to 1C are diagrams illustrating a structure of a light-emitting element. [Diagram 5] 1A and 1B are diagrams illustrating a light-emitting device. [Figure 6] 1A and 1B are diagrams illustrating a light-emitting device. [Figure 7] 1A to 1C are diagrams illustrating electronic devices. [Figure 8] 1A to 1C are diagrams illustrating electronic devices. [Figure 9] FIG. [Figure 10] 1H-NMR chart of the dibenzo[f,h]quinoxaline derivative shown in structural formula (100). [Figure 11] UV-visible absorption and emission spectra of the dibenzo[f,h]quinoxaline derivative shown in structural formula (100). [Figure 12] UV-visible absorption and emission spectra of the dibenzo[f,h]quinoxaline derivative shown in structural formula (100). [Figure 13] 1H-NMR chart of the dibenzo[f,h]quinoxaline derivative shown in structural formula (101). [Figure 14] UV-visible absorption and emission spectra of the dibenzo[f,h]quinoxaline derivative shown in structural formula (101). [Figure 15]UV-visible absorption and emission spectra of the dibenzo[f,h]quinoxaline derivative shown in structural formula (101). [Figure 16] 1H-NMR chart of the dibenzo[f,h]quinoxaline derivative shown in structural formula (102). [Figure 17] UV-visible absorption and emission spectra of the dibenzo[f,h]quinoxaline derivative shown in structural formula (102). [Figure 18] UV-visible absorption and emission spectra of the dibenzo[f,h]quinoxaline derivative shown in structural formula (102). [Figure 19] 1H-NMR chart of the dibenzo[f,h]quinoxaline derivative shown in structural formula (103). [Figure 20] UV-visible absorption and emission spectra of the dibenzo[f,h]quinoxaline derivative shown in structural formula (103). [Figure 21] UV-visible absorption and emission spectra of the dibenzo[f,h]quinoxaline derivative shown in structural formula (103). [Figure 22] 1A to 1C illustrate structures of a light-emitting element 1, a light-emitting element 2, and a comparative light-emitting element 3. [Figure 23] 13 shows current density-luminance characteristics of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. [Figure 24] 13 shows voltage-luminance characteristics of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. [Diagram 25] 13 shows luminance-current efficiency characteristics of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. [Figure 26] 13 shows voltage-current characteristics of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. [Figure 27] FIG. 1 shows emission spectra of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. [Figure 28] 13 shows the reliability of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. [Figure 29] FIG. 13 shows current density-luminance characteristics of the light-emitting element 4. [Diagram 30]FIG. 13 shows voltage-luminance characteristics of the light-emitting element 4. [Diagram 31] FIG. 13 shows luminance vs. current efficiency characteristics of the light-emitting element 4. [Diagram 32] FIG. 13 shows voltage-current characteristics of the light-emitting element 4. [Diagram 33] FIG. 13 shows an emission spectrum of the light-emitting element 4. [Diagram 34] FIG. 13 shows the reliability of the light-emitting element 4. [Diagram 35] 1H-NMR chart of the dibenzo[f,h]quinoxaline derivative shown in structural formula (122). [Diagram 36] 13 shows current density-luminance characteristics of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. [Figure 37] 13 shows voltage-luminance characteristics of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. [Figure 38] 13 shows luminance-current efficiency characteristics of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. [Figure 39] 13 shows voltage-current characteristics of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. [Diagram 40] 13 shows emission spectra of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. FIG. [Diagram 41] 13 shows the reliability of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. [Diagram 42] FIG. 13 is a graph showing current density-luminance characteristics of the light-emitting element 8. [Diagram 43] FIG. 13 shows voltage-luminance characteristics of the light-emitting element 8. [Diagram 44] FIG. 13 shows luminance vs. current efficiency characteristics of the light-emitting element 8. [Diagram 45] FIG. 13 is a graph showing voltage-current characteristics of the light-emitting element 8. [Diagram 46] FIG. 2 shows an emission spectrum of the light-emitting element 8. [Figure 47] FIG. 13 is a graph showing voltage-current characteristics of the light-emitting element 1A during a storage test. [Figure 48] FIG. 13 is a graph showing luminance vs. external quantum efficiency characteristics of the light-emitting element 1A in a storage test. [Figure 49]FIG. 13 is a graph showing voltage-current characteristics of the light-emitting element 2A during a storage test. [Figure 50] FIG. 13 is a graph showing luminance vs. external quantum efficiency characteristics of the light-emitting element 2A in a storage test. [Figure 51] FIG. 13 is a graph showing voltage-current characteristics of the comparative light-emitting element 3A in a storage test. [Figure 52] FIG. 13 shows luminance vs. external quantum efficiency characteristics of the comparative light-emitting element 3A in a storage test. [Figure 53] FIG. 13 is a graph showing voltage-current characteristics of the light-emitting element 4A during a storage test. [Figure 54] FIG. 13 shows luminance vs. external quantum efficiency characteristics of the light-emitting element 4A in a storage test. [Figure 55] FIG. 13 is a graph showing voltage-current characteristics of the light-emitting element 8A during a storage test. [Figure 56] FIG. 13 is a graph showing luminance vs. external quantum efficiency characteristics of the light-emitting element 8A in a storage test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Hereinafter, the embodiment 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 form and details are not limited thereto without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the above embodiment. It is not to be construed as being limited to the following:

[0037] The words "membrane" and "layer" may be interchangeable depending on the situation. For example, the term "conductive layer" can be used interchangeably with the term "conductive film." ". Alternatively, for example, the term "insulating film" may be used. It may be possible to change the term to "insulating layer."

[0038] (Embodiment 1) In this embodiment, a light-emitting element which is one embodiment of the present invention will be described.

[0039] The light-emitting element shown in this embodiment has a pair of electrodes (a first electrode (anode) and a second electrode (cathode) The EL layer, which contains a light-emitting layer, is sandwiched between the electrons. The EL layer contains holes (or hols) in addition to the light-emitting layer. The layer includes a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, etc. It is done.

[0040] When a voltage is applied to the light-emitting element, holes injected from the first electrode side and the second electrode side are The electrons injected from the electrode side recombine in the light-emitting layer, and the resulting energy This causes the luminescent material contained in the luminescent layer to emit light.

[0041] In this case, the light-emitting layer 100 contains a first layer having an electron transport property and a hole transport property as shown in FIG. The organic compound (h) 101 having the hole transporting property, the second organic compound (a) 102 having the hole transporting property, and The first organic compound (h) 101 and the second organic compound (h) 102 are included. The organic compound (a) 102 is an excited complex (also called an exciplex). That is, at least 10 of the first organic compound (h) forms a 1's Lowest Unoccupied Molecular Orbital (LUMO) ar Orbital) level is lower than the LUMO level of the second organic compound (a)102 , and the highest occupied molecular orbital (HOMO) of the first organic compound (h) 101 The Occupied Molecular Orbital level is the second organic compound (a ) lower than the HOMO level of 102. Therefore, the excitation energy of the resulting exciplex is As shown, the LUMO level (LUMO(h)) of the first organic compound (h) 101 and the LUMO level (LUMO(h)) of the second organic compound (h) 102 are The energy difference between the HOMO level of the organic compound (a) and the HOMO level of the organic compound (a) is That is, ΔE in the figure e ) is affected.

[0042] In such a light-emitting layer 100, the emission spectrum of the exciplex and the absorption spectrum of the light-emitting substance (guest material) are Energy transfer can be performed by utilizing the overlap with the absorption spectrum. A light-emitting element having high transfer efficiency and high external quantum efficiency can be realized. To electrically excite ΔE e This requires electrical energy (i.e. voltage) equivalent to However, this ΔE e is the energy required to electrically excite the first organic compound (h) 101. -ΔE h and the energy ΔE required to electrically excite the second organic compound (a) 102. a That is, in such a light-emitting layer 100, the driving voltage ( The photoinitiation voltage can be reduced.

[0043] In this case, the first organic compound (h) 101 and the second organic compound (a) 102 are not used, ΔE e The light-emitting layer is made of one organic compound having a HOMO-LUMO gap corresponding to 0, it is possible to obtain a low driving voltage (light emission start voltage) similar to that of the light emitting layer 100. However, in one organic compound, the triplet excitation energy is much lower than the singlet excitation energy. The triplet excitation energy is then transferred to the luminescent material (guest material). It is difficult to transfer energy to the exciplex and have it contribute to light emission. It has the characteristic that the singlet excitation energy and triplet excitation energy are located at almost the same position. Therefore, both singlet excitation energy and triplet excitation energy are transferred to the luminescent material. As a result, in addition to the effect of lowering the voltage, the effect of increasing efficiency can be obtained. The details of the mechanism of high efficiency mentioned here are as follows.

[0044] When the luminescent material is a phosphorescent compound, the singlet excitation energy and triplet excitation energy of the exciplex are The energy of both the phosphorescent compound and the triplet excited state is transferred to the triplet excited state. This is most preferable from the viewpoint of high efficiency because the emitted light from the

[0045] In addition, when the luminescent substance is a thermally activated delayed fluorescent compound, the singlet excitation energy of the exciplex is Energy is transferred to the singlet excited state of the luminescent material, and light is emitted from the singlet excited state (i.e. The triplet excitation energy of the exciplex can be converted into a luminescent material. Energy is transferred to the triplet excited state of the nucleonyl group, but the triplet excited state is partially or completely activated by thermal activation. or all of the luminescent material undergoes reverse intersystem crossing to the singlet excited state and is finally converted to fluorescent emission. This results in high efficiency.

[0046] In addition, when the luminescent substance is a fluorescent compound, the singlet excitation energy of the exciplex is Energy is transferred to a singlet excited state, and light is emitted from the singlet excited state (i.e., fluorescence emission). On the other hand, the triplet excitation energy of the exciplex can be converted to the triplet excitation energy of the luminescent material. At first glance, it may not seem possible to achieve high efficiency because the energy is transferred to the activated state and thermally deactivated. However, the energy donor exciplexes can transfer singlet excitation energy and triplet excitation energy. Since the difference in excitation energy is small, the exciplex itself has the property of exhibiting thermally activated delayed fluorescence. In other words, the triplet excited state of the exciplex undergoes reverse intersystem crossing partially or entirely to the singlet excited state. The ratio of singlet excitons increases compared to normal. The proportion of singlet excitons increases, and the singlet excitation energy is transferred to the singlet excited state of the luminescent material. Since energy transfer occurs, even if a fluorescent compound is used as a luminescent material, This phenomenon is also one of the features of the present invention.

[0047] In this way, the light-emitting device in which the exciplex is used as the energy donor in the light-emitting layer can emit light with a phosphorescent compound. The present invention uses any of the following compounds as luminescent substances: thermally activated delayed fluorescent compounds, fluorescent compounds, etc. Although this is useful in some cases, problems may arise in terms of controlling the light-emitting region.

[0048] As mentioned above, at least the LUMO level (LU The LUMO level (LUMO(h)) of the second organic compound (a) 102 is higher than the LUMO level (LUMO(a)) of the second organic compound (a). The energy level is low, and the HOMO level of the first organic compound (h) 101 (HOMO (h)) is more energetic than the HOMO level (HOMO(a)) of the second organic compound (a)102. The low energy level of the first organic compound (h) 101 and the second organic compound (a) 10 In particular, in the conventional method, the exciplex is formed in the light-emitting layer 100. In the light-emitting device in which the first organic compound (h) 101 is used as an energy donor, O level (HOMO(h)) and the HOMO level of the second organic compound (a)102 (HOMO( a)) and the energy difference ΔE HOMO By making For example, the first organic compound (h) 101 is 2-[3'-(dibenzo Thiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation :2mDBTBPDBq-II) as the second organic compound (a) 102, 1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H- Carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBB When iF is used, the HOMO level (HOMO(h)) of the first organic compound (h) 101 is -6.22 eV, whereas the HOMO level (HO Since MO(a) is -5.36 eV, ΔE HOMO is 0.86 eV.

[0049] Thus, the HOMO level (HOMO(h)) of the first organic compound (h) 101 and the HOMO level (HOMO(h)) of the second organic compound (h) 102 are The difference in the HOMO levels (HOMO(a)) of organic compounds (a)102 (ΔE HOMO ) is large In this case, the carrier dispersion is controlled by the content of the second organic compound (a) 102 in the light-emitting layer 100. In other words, if the amount of the second organic compound (a) 102 is too small, the electric Excessive electrons, i.e. the light-emitting area is biased toward the anode, but the amount is slightly more than optimal. However, this time there will be an excess of holes, i.e. the holes will escape to the cathode side. In the case of a small number of devices, even if the first organic compound (h) 101 and the second organic compound (a) Even if the mixture ratio of 102 is exquisitely optimized, the carrier balance may be slightly disturbed by long-term operation. When the recombination efficiency is reduced, the luminance is deteriorated. HOM OWhen the electron transport layer 100 is large, holes are accumulated in the second organic compound (a) 102, and the electron transport layer 100 is On the other hand, the recombination region in the light-emitting layer 100 is wider. However, since the entire light-emitting layer 100 can be utilized, it can be said that the reliability is higher.

[0050] In addition, the electron injection capability of the light-emitting element decreases with deterioration of the electron injection electrode (cathode), etc. Long-term operation often causes the recombination region to shift toward the cathode. Therefore, if the light-emitting layer 100 has poor hole transport properties, the average distance that the holes have to be transported to the light-emitting layer 100 becomes long. In other words, when driven at a constant current, the driving voltage increases over time. The HOMO level (HOMO(h)) of the first organic compound (h) and the HOMO level (HOMO(h)) of the second organic compound (h) The difference in the HOMO level (HOMO(a)) of organic compound (a) (ΔE HOMO ) is large In the case of the light-emitting layer 100, since holes are unlikely to move in the light-emitting layer 100, this problem is likely to become more pronounced. do.

[0051] In the light-emitting device, the above-mentioned exciplex is used as an energy donor in the light-emitting layer 100. One aspect of the light-emitting device of the present invention is to solve the above problems. The EL layer has an emitting layer 100 between the first and second layers. The emitting layer 100 has electron transport properties and A first organic compound (h) 101 having a hole transporting property and a second organic compound (h) having a hole transporting property. The compound (a) 102 and the luminescent material are included, and the first organic compound (h) 101 and the second organic compound (h) 102 are included. The organic compound (a) 102 is a combination that forms an exciplex, and the first organic compound (h The HOMO level (HOMO(h)) of the second organic compound (a) is MO(a)) and is equal to the HOMO level (HOMO(h)) of the first organic compound (h). , the difference between the HOMO level (HOMO(a)) of the second organic compound (a) is 0.4 eV or less The light-emitting element is characterized in that:

[0052] With this structure, some of the holes are transported not only to the second organic compound (a) 102 but also to The first organic compound (h) 101 is also injected. As a result, the second organic compound (a) 10 Since holes are less likely to accumulate in the light-emitting layer 100, the carrier balance is easily maintained. It is possible to obtain a light-emitting device with a wide recombination region at low current. In this case, the voltage rise in the first organic compound (h) can be suppressed. Recombination can also occur at 1 to form an excited state of the first organic compound, but this is rapid. Since the photoexciplex is quickly converted to an exciplex, the high efficiency effect of using the exciplex mentioned above is also achieved. In addition, the holes are mainly injected into the second organic compound (a) 102. Therefore, the effect of lowering the driving voltage (light emission start voltage) is also maintained.

[0053] Thus, ΔE HOMO While keeping the first effective The organic compound (h) 101 and the second organic compound (a) 102 form an exciplex, The above-mentioned problems can be solved. From the viewpoint of injecting holes into the organic compound (h) 101 of 1, ΔE HOMO is 0.3 eV The following is more preferred:

[0054] In addition, compounds suitable for realizing the above concept are as follows. First, the first organic compound (h) 101 contains a 6-membered nitrogen-containing heteroaromatic ring and a carbazole skeleton, and is a tricyclic ring. It is preferable that the compound does not contain an arylamine skeleton. That is, the compound does not contain a six-membered nitrogen-containing heteroaromatic ring. The compound has an electron transporting property and contains a carbazole skeleton and a triarylamine skeleton. It is preferable to use a compound that does not have a second function and thus has a moderate hole transporting property. The organic compound (a) 102 is a compound having a hole transporting property, and the first organic compound (h) 1 In order to make the HOMO level higher than that of 01, it is preferable to include a triarylamine skeleton. .

[0055] Many compounds containing triarylamine skeletons have been reported to be stable by cyclic voltammetry (CV) measurements. According to the calculation, the HOMO level is around -5.5 eV or higher. The HOMO level of 9-phenylcarbazole is -5.88 eV, so the difference is 0.4 Therefore, in one embodiment of the present invention, the first organic compound The carbazole skeleton of the compound (h) 101 preferably contains a bicarbazole skeleton. This is because bicarbazole has a higher HOMO level than 9-phenylcarbazole. In particular, when 3,3'-bicarbazole or 2,3'-bicarbazole structures are introduced, Since the HOMO level is in the vicinity of −5.6 to −5.7 eV, the first Suitable for organic compound (h) 101.

[0056] In addition, the above-mentioned six-membered nitrogen-containing heteroaromatic ring includes pyridine, pyrazine, pyrimidine, These six-membered rings include diazines such as pyridazine, triazines, and tetrazines. The nitrogen-containing heteroaromatic ring may further be condensed with a benzene ring or the like. For example, The 6-membered nitrogen-containing heteroaromatic rings condensed with rings include quinoline, isoquinoline, dibenzo[ f,h] quinoline. Also, quinoxaline, quinazoline, and phthalazine are representative. naphthyridine, dibenzo[f,h]quinoxaline, dibenzo[f,h]quinazoline etc. are also useful.

[0057] In one embodiment of the present invention, as described above, not only the second organic compound (a) 102, It is preferable to inject holes into the first organic compound (h) 101 and transport them. As shown in FIG. 2, the first organic compound (h) 101 and the second organic compound (h) 102 in the light-emitting layer 100 In order to enhance hole injection into both the organic compound (a) 102 and the light-emitting layer 100, The hole transport layer 104 is formed by using a third organic compound (p) 105 having a hole transport property. The HOMO level (HOMO(p)) of the organic compound (p) 105 is equal to that of the second organic compound (a) 10 It is preferable that the HOMO level of the 2-compound is lower than the HOMO level of the 2-compound (HOMO(a)). The HOMO level (HOMO(p)) of the third organic compound (p) 105 is (a) HOMO level of 102 (HOMO(a)) and the HO of the first organic compound (h) 101 The third organic compound (p) 105 is selected so that its valence level is between the HOMO (h) and It is more preferable to do so.

[0058] A specific example of a light-emitting element having the above structure according to one embodiment of the present invention will be described below with reference to FIG. I will use this to explain.

[0059] The first electrode (anode) 201 and the second electrode (cathode) 203 are made of a metal, an alloy, an electrically conductive material, or the like. In particular, indium oxide, Indium Tin Oxide, silicon or silicon oxide Indium oxide-tin oxide, Indium oxide-zinc oxide ide), indium oxide containing tungsten oxide and zinc oxide, gold (Au), platinum (Pt), Nickel (Ni), Tungsten (W), Chromium (Cr), Molybdenum (Mo ), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), titanium (Ti) In addition, elements in the first or second group of the periodic table, such as lithium (Li) and cesium (Ce), Alkali metals such as Cs, calcium (Ca), strontium (Sr), etc. Alkaline earth metals, magnesium (Mg), and alloys containing these (MgAg, Al Li), europium (Eu), ytterbium (Yb), and other rare earth metals, An alloy containing ZnO, graphene, etc. can be used. The second electrode (cathode) 203 is formed by, for example, sputtering or deposition (including vacuum deposition). It can be formed by, for example,

[0060] The hole injection layer 211 injects holes into the light emitting layer 213 via the hole transport layer 212 having high hole transport properties. This is the injection layer, which is made of a substance with high hole transport properties (also called a hole transport compound) and an acceptor. The layer contains a material with high hole transport properties and a material with high acceptor properties. The scepter material removes electrons from the material with high hole transport properties, generating holes. Holes are injected into the light-emitting layer 213 through the hole-transporting layer 212. The layer 12 is formed using a material with high hole transporting properties.

[0061] The hole-injection layer 211 and the hole-transport layer 212 may be formed of a material having a high hole-transporting property. For example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD) and N,N'-bis(3-methylphenyl)-N,N'-diphenyl Nyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4 ''-Tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), 4, 4',4''-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDA TA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino ]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9 '-Bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB) Which aromatic amine compound, 3-[N-(9-phenylcarbazol-3-yl)-N-phenyl phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[ N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazol Rubazol (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenyl PCzPCN 1) and others. Other examples include 4,4'-di(N-carbazolyl)biphenyl (abbreviation: C BP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: T CPB), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-cal Carbazole derivatives such as CzPA (abbreviation: CzPA) can be used. The substances mentioned are mainly 1×10 -6 cm 2A material that has a hole mobility of 1 / Vs or more. However, other substances may be used as long as they have a higher hole transporting property than an electron transporting property.

[0062] In addition, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylphosphine) nylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenyl Amino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide]( abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis (phenyl)benzidine (abbreviation: Poly-TPD) and other polymer compounds. It is also possible.

[0063] The acceptor material used in the hole injection layer 211 is selected from the group consisting of the 4th group of the periodic table of elements. Examples of the oxides of metals belonging to groups 1 to 8 include molybdenum oxide. is particularly preferred.

[0064] The light-emitting layer 213 is a layer containing a light-emitting substance. However, the light-emitting layer 213 has the structure shown in FIG. In this case, the first organic compound having an electron transport property and a hole transport property described later and the The first organic compound includes a second organic compound having a hole transporting property and a light emitting substance. The organic compound and the second organic compound are used to induce recombination of carriers (electrons and holes) in the light-emitting layer. A combination that can form an excited complex (also called an exciplex) when combined with In the light-emitting layer, an exciplex is formed, and the fluorescent spectrum of the first organic compound is increased. The fluorescence spectra of the first and second organic compounds are closer to the longer wavelength exciplexes. The emission spectrum of the exciplex and the absorption spectrum of the guest material are then converted into an emission spectrum. The first and second organic compounds are selected so that the spectrum overlaps greatly. By doing so, it is possible to maximize the energy transfer from the singlet excited state. For triplet excited states, energy transfer occurs from the exciplex rather than from the host material. It is thought that.

[0065] The first organic compound and the second organic compound may be any combination that generates an exciplex. However, there are compounds that easily accept electrons (electron trapping compounds) and compounds that easily accept holes. It is preferable to combine the first organic compound with a hole trapping compound. It is preferable that the material be capable of trapping (or transporting) not only electrons but also holes, so that the material is a six-membered A compound having a nitrogen-containing heteroaromatic ring and a bicarbazole skeleton, and a triaryl A compound not containing an amine skeleton is preferred. For example, a compound represented by the following general formula (G0) This is preferable.

[0066] [ka]

[0067] (In the formula, A represents a dibenzo[f,h]quinoxalinyl group, R 1 ~R 15 are respectively Independently, hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted a cycloalkyl group having 5 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 13 carbon atoms, Ar represents a substituted or unsubstituted arylene group having 6 to 25 carbon atoms, or represents a single bond. Note that the arylene group of Ar does not include an anthracenylene group. is preferred.)

[0068] In addition, when Ar contains an anthracenylene group, the triplet excitation energy of the compound is large (1 0.7 eV or less), quenching the triplet excitation energy of the exciplex. Therefore, the arylene group of Ar does not include an anthracenylene group. is preferred.

[0069] More specifically, the compounds represented by the above general formulas (G1) to (G3) are suitable. Specifically, for example, 2-{4-[3-(N-phenyl-9H-carbazole-3-yl) phenyl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline(abbreviation Name: 2PCCzPDBq), 2-{3-[3-(N-phenyl-9H-carbazole-3 -yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation 2mPCCzPDBq), 2-{4-[2-(N-phenyl-9H-carbazole -3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxa Phosphorus (abbreviation: 2PCCzPDBq-02) and 2-{3-[2-(N-phenyl-9 H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[ f,h]quinoxaline (abbreviation 2mPCCzPDBq-02).

[0070] Compounds that readily accept holes include, for example, 4-phenyl-4'-(9-phenyl- (phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP) , 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino] -9-phenylcarbazole (abbreviation: PCzPCN1), 4,4',4''-tris[N -(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNAT A), 2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]- Spiro-9,9'-bifluorene (abbreviation: DPA2SF), N,N'-bis(9-phenyl) (abbreviation)-N,N'-diphenylbenzene-1,3-diamine : PCA2B), N-(9,9-dimethyl-2-N',N'-diphenylamino-9H- Fluoren-7-yl)diphenylamine (abbreviation: DPNF), N,N',N''-triphenylamine Phenyl-N,N',N''-tris(9-phenylcarbazol-3-yl)benzene -1,3,5-triamine (abbreviation: PCA3B), 2-[N-(9-phenylcarbazol PCA SF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro- 9,9'-Bifluorene (abbreviation: DPASF), N,N'-bis[4-(carbazole- 9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7- Diamine (abbreviation: YGA2F), 4,4'-bis[N-(3-methylphenyl)-N- 4,4'-bis[N-(4-diphenylamino)biphenyl (abbreviation: TPD) N-(9,9-aminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), Dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2[N'-phenyl -N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren 3-[N-(9-phenyl-7-yl)phenylamine (abbreviation: DFLADFL), Carbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3-[N-(4-diphenylaminophenyl)-N-phenylamino ]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-di phenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N' -phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD) , 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino ]-9-phenylcarbazole (abbreviation: PCzTPN2), 3,6-bis[N-(9-phenyl phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole ( Examples of compounds having a triarylamine skeleton include compounds such as PCzPCA2).

[0071] The first organic compound and the second organic compound described above are not limited to these specific examples. The combination is such that an exciplex can be formed, and the emission spectrum of the exciplex is similar to that of the luminescent material. The emission spectrum of the exciplex overlaps with the absorption spectrum of the luminescent material. It is sufficient that the wavelength is longer than the peak of the torr.

[0072] The first organic compound is a compound that easily accepts electrons and a compound that easily accepts holes. When the first organic compound is mixed with the second organic compound, the carrier balance can be controlled by the mixture ratio. Specifically, the ratio of the first organic compound to the second organic compound is in the range of 1:9 to 9:1. is preferred.

[0073] In the light-emitting layer 213, the following materials can be used as the light-emitting material and the light-emitting center material: is a luminescent material that converts singlet excitation energy into light emission, or triplet excitation energy into light emission. The above-mentioned luminescent materials and the like can be used alone or in combination. Examples of the substance and the luminescence center substance include the following.

[0074] Examples of luminescent substances that convert singlet excitation energy into luminescence include fluorescent substances (fluorescent photoactive compounds).

[0075] The fluorescent substance is N,N'-bis[4-(9H-carbazol-9-yl)fluorene]. [phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S) , 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl) Triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4 '-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAP PA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl ]-9H-Carbazole-3-amine (abbreviation: PCAPA), Perylene, 2,5,8,1 1-Tetra-tert-butylperylene (TBP), 4-(10-phenyl-9- Anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenyl PCBAPA, N,N''-(2-tert-butylanthracene-9, 10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4- phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9, 10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation Name: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl ]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPP A) N,N,N',N',N'',N'',N'''',N'''-Octaphenyldibenzyl Chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Phosphorus 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H -Carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1' -Biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol N-(9,10-diphenyl-2-anthracene) (aryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPA PA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl] -N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPh A), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carba 2YG ABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAP hA), Coumarin 545T, N,N'-Diphenylquinacridone (abbreviation: DPQd), 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyl ether Thracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethene {6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM 1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-beta 4H-pyran-4-ylidene)propane DCM2, N,N,N',N'-tetrakis(4-methylphenyl) p-mPhTD, 7,14-diphenyl -N,N,N',N'-Tetrakis(4-methylphenyl)acenaphtho[1,2-a]phenyl Phosphoranthene-3,10-diamine (abbreviation: p-mPhAFD), {2-isopropyl- 6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5 H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene Propanedinitrile (abbreviation: DCJTI), {2-tert-butyl-6-[2-(1, 1,7,7-Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij ]Quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitri (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl ]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM ), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3 ,6,7-Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl ]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), etc. Examples include:

[0076] Examples of luminescent materials that convert triplet excitation energy into luminescence include phosphorescent materials ( Fluorescent compounds and thermally activated delayed fluorescence (TADF) materials The delayed fluorescence in TADF materials is similar to that of normal fluorescence. It is a type of light emission that has a spectrum and has a very long lifespan. Its lifespan is about 10 -6 More than a second, Preferably 10 -3 More than seconds.

[0077] Phosphorescent substances include bis{2-[3',5'-bis(trifluoromethyl)phenyl]phenyl Nyl]pyridinato-N,C 2’}Iridium(III) picolinate (abbreviation: Ir(CF 3ppy)2(pic)), bis[2-(4',6'-difluorophenyl)pyridinato -N,C 2’ ]Iridium(III) acetylacetonate (abbreviation: FIracac), Tris(2-phenylpyridinato)iridium(III) (abbreviation: Ir(ppy)3), Bis(2-phenylpyridinato)iridium(III) acetylacetonate (abbreviation: I r(ppy)2(acac)), tris(acetylacetonato)(monophenanthroline ) terbium(III) (abbreviation: Tb(acac)3(Phen)), bis(benzo[h ]quinolinato)iridium(III) acetylacetonate (abbreviation: Ir(bzq)2( acac)), Bis(2,4-diphenyl-1,3-oxazolato-N,C 2’ ) Iridi Ir(III) acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{ 2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2’}iridium (III) Acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)), Bis(III) S(2-phenylbenzothiazolato-N,C 2’ ) Iridium(III) acetylacetonate Ir(bt)2(acac)), bis[2-(2'-benzo[4,5-a ]Thienyl)pyridinato-N,C 3’ ]Iridium(III) acetylacetonate (abbreviation Name: Ir(btp)2(acac)), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(piq)2(acac)) , (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato ]Iridium(III) (abbreviation: Ir(Fdpq)2(acac)), (acetylacetonate Nato)bis(3,5-dimethyl-2-phenylpyrazinate)iridium(III)(abbreviation : [Ir(mppr-Me)2(acac)]), (acetylacetonato)bis(5-acetylacetonato) isopropyl-3-methyl-2-phenylpyrazinate)iridium(III) (abbreviation: [I r(mppr-iPr)2(acac)]), (acetylacetonato)bis(2,3,5 -Triphenylpyrazinate)iridium(III) (abbreviation: Ir(tppr)2(aca c)) Bis(2,3,5-triphenylpyrazine)(dipivaloylmethanate)iridide Ir(III) (abbreviation: [Ir(tppr)2(dpm)]), (acetylacetonate) Bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation :[Ir(tBuppm)2(acac)]), (acetylacetonato)bis(4,6- Diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(aca c)]), 2,3,7,8,12,13,17,18-octaethyl-21H,23H- Porphyrin platinum (II) (abbreviation: PtOEP), tris(1,3-diphenyl-1,3 -propanedionato)(monophenanthroline)europium(III)(abbreviation:Eu( DBM)3(Phen)), tris[1-(2-thenoyl)-3,3,3-trifluoro Acetonato](monophenanthroline)europium(III) (abbreviation: Eu(TTA) 3(Phen)).

[0078] In addition, TADF materials include, for example, fullerene and its derivatives, and activators such as proflavine. Lysine derivatives, eosin, etc. Magnesium (Mg), zinc (Zn), Cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or para Examples of the metal-containing porphyrin include porphyrins containing palladium (Pd) and the like. For example, protoporphyrin-tin fluoride complex (SnF2(Proto IX) ), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin Hemato IX complex (SnF2(Hemato IX)), coproporphyrin tetrachloride Trimethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octyl Triethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin Tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride complex Furthermore, 2-(biphenyl-4-yl)-4, 6-Bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3 ,5-triazine (PIC-TRZ) and other π-electron rich heteroaromatic rings and π-electron deficient heteroaromatic rings A heterocyclic compound having an aromatic ring can also be used. In the case of a substance in which an electron-deficient heteroaromatic ring is directly bonded, the donor property of the π-electron-rich heteroaromatic ring and the π The acceptor properties of the electron-deficient heteroaromatic rings are both strong, and the energy difference between S1 and T1 is small. This is particularly preferred since it reduces the

[0079] The light-emitting layer 213 may have a laminated structure as shown in FIG. In this case, each layer of the laminated layers emits light. For example, the first layer The light-emitting layer 213(a1) is configured to emit fluorescent light, and the second layer laminated on the first layer The first light-emitting layer 213(a2) may be configured to emit phosphorescence. In the layer from which phosphorescence is obtained, the exciplex is It is preferable that the light emission is obtained by energy transfer from the dopant to the organic compound. Regarding the color of emitted light, if one layer emits blue light, the other layer emits orange light. In addition, the layers may be configured to emit light in multiple colors or yellow. A configuration containing several kinds of dopants may also be used.

[0080] The electron transport layer 214 is a layer containing a substance with high electron transporting properties (also called an electron transporting compound). The electron transport layer 214 contains tris(8-quinolinolato)aluminum(III) (abbreviation : Alq3), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation :Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)al bis[2-(2-hydroxyphenyl)benzo[III](abbreviation: BAlq) oxazolato]zinc(II) (abbreviation: Zn(BOX)2), bis[2-(2-hydroxy Metal complexes such as phenyl)benzothiazolato]zinc(II) (abbreviation: Zn(BTZ)2) Also, 2-(4-biphenylyl)-5-(4-tert-butyl phenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p -tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene( Abbreviation: OXD-7), 3-(4'-tert-butylphenyl)-4-phenyl-5-( 4''-biphenyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-ter t-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1, 2,4-Triazole (abbreviation: p-EtTAZ), Bathophenanthroline (abbreviation: BPh en), Bathocuproine (abbreviation: BCP), 4,4'-bis(5-methylbenzoxa Heteroaromatic compounds such as (2-phenyl-2-yl)stilbene (abbreviation: BzOs) can also be used. In addition, poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9- Dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)](abbreviation Name: PF-Py), Poly[(9,9-dioctylfluorene-2,7-diyl)-co- (2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) Compounds can also be used. The substances mentioned here are mainly 1×10 -6 cm 2 / Vs or more In addition, if a material has a higher electron transporting property than a hole transporting property, Materials other than those listed above may also be used for the electron-transporting layer 214 .

[0081] The electron transport layer 214 may be a single layer or a laminate of two or more layers made of the above-mentioned materials. The structure may be such that

[0082] The electron injection layer 215 is a layer containing a substance with high electron injection properties. Lithium fluoride (LiF), Cesium fluoride (CsF), Calcium fluoride (CaF2), Lithium oxide (LiO x ) and the like, alkali metals, alkaline earth metals, or Compounds of the formula: In addition, an electride may be used for the electron injection layer 215. The electride is, for example, a mixed oxide of calcium and aluminum with electrons. The above-mentioned material constituting the electron transport layer 214 may be a material containing a high concentration of can also be used.

[0083] In addition, the electron injection layer 215 is made of a composite material obtained by mixing an organic compound and an electron donor. Such composite materials are made by adding electrons to organic compounds by electron donors. In this case, the organic compound is: It is preferable that the material has excellent transport properties for the generated electrons. Specifically, for example, the above-mentioned The substance constituting the electron transport layer 214 (metal complex, heteroaromatic compound, etc.) can be used. The electron donor may be any substance that exhibits electron donating properties to organic compounds. The metal is preferably an alkali metal, an alkaline earth metal, or a rare earth metal, and more preferably lithium, cesium, maium, or the like. Examples of the metals include magnesium, calcium, erbium, and ytterbium. Metal oxides and alkaline earth metal oxides are preferred, and lithium oxide, calcium oxide, Barium oxide and the like can be used. In addition, a Lewis base such as magnesium oxide can be used. It is also possible to use organic compounds such as tetrathiafulvalene (TTF). It is also possible.

[0084] The hole injection layer 211, the hole transport layer 212, the light emitting layer 213, and the electron transport layer 214 The electron injection layer 215 is formed by a deposition method (including a vacuum deposition method), an inkjet method, a coating method, and the like, respectively. It can be formed by a method such as a cloth method.

[0085] The light-emitting element described above emits light by recombination of holes and electrons in the EL layer 202. This light emission is caused by either the first electrode 201 or the second electrode 203 or Therefore, the first electrode 201 and the second electrode 203 are connected to each other. Either one or both of these electrodes is a light-transmitting electrode.

[0086] Note that the light-emitting element described in this embodiment has an emission spectrum of an exciplex and a phosphorescent compound ( Energy transfer can be achieved by utilizing the overlap of the absorption spectrum of the Therefore, a light-emitting element having high energy transfer efficiency and high external quantum efficiency can be realized.

[0087] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. It is possible to do so.

[0088] (Embodiment 2) In this embodiment, a dibenzo[f, h]Quinoxaline derivatives are described.

[0089] The dibenzo[f,h]quinoxaline derivative according to one embodiment of the present invention is represented by the following general formula (G0): Represented.

[0090] [ka]

[0091] In the formula, A represents a dibenzo[f,h]quinoxalinyl group, R 1 ~R 15 Is that each independently represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, Substituted cycloalkyl group having 5 to 7 carbon atoms, substituted or unsubstituted aryl group having 6 to 13 carbon atoms Ar represents a substituted or unsubstituted arylene group having 6 to 25 carbon atoms; or a single bond. Note that the arylene group of Ar does not include an anthracenylene group. It is preferred.

[0092] The dibenzo[f,h]quinoxaline derivative represented by the above general formula (G0) is First, as shown in the following synthesis scheme (a), , a halogen compound of a dibenzo[f,h]quinoxaline derivative (A1) and bicarbazole The dibenzo[f,h] ]The quinoxaline derivative (G0) is obtained.

[0093] [ka]

[0094] In the formula, A represents a dibenzo[f,h]quinoxalinyl group, and R 1 ~R 15 Is that each independently represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, Substituted cycloalkyl group having 5 to 7 carbon atoms, substituted or unsubstituted aryl group having 6 to 13 carbon atoms Ar represents a substituted or unsubstituted arylene group having 6 to 25 carbon atoms; or a single bond. Note that the arylene group of Ar does not include an anthracenylene group. It is preferable that X represents a halogen atom. It is also preferable that Ar is a substituted or unsubstituted group having a carbon number of When B is an arylene group having a length of 6 to 25, B is a boronic acid or a boronic ester or a cyclic aryl group. The cyclic triol borate salts include lithium salts. Alternatively, potassium salts and sodium salts may be used. When Ar is a single bond, B is hydrogen. Represents.

[0095] In addition, as shown in the following synthesis scheme (b), dibenzo[f,h]quinoxaline derivatives can be synthesized. The halogen compound (A1) is reacted with a halogen-substituted arylboronic acid (B1). After obtaining intermediate (B2) by the reaction with bicarbazole derivative (B3), By subjecting the reaction to the above reaction, the dibenzo[f,h]quinoxaline derivative (G0) can be obtained.

[0096] [ka]

[0097] In the formula, A represents a dibenzo[f,h]quinoxalinyl group, and R 1 ~R 15 Is that each independently represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, Substituted cycloalkyl group having 5 to 7 carbon atoms, substituted or unsubstituted aryl group having 6 to 13 carbon atoms Ar represents a substituted or unsubstituted arylene group having 6 to 25 carbon atoms; or a single bond. Note that the arylene group of Ar does not include an anthracenylene group. It is preferable that X represents a halogen. B represents a boronic acid or a boronic acid ester. or cyclic triol borate salt, etc.

[0098] When Ar in general formula (G0) represents a single bond, (A1) and (B3) are reacted as they are. Just let them do it.

[0099] Next, a dibenzofuran, which is one embodiment of the present invention, can be synthesized by the above-mentioned synthesis method. [f,h] The quinoxaline derivative is more preferably represented by the above general formulas (G1) to (G3). The compound according to the present invention is represented by the general formulas (G0) to (G3). The specific structural formula of the dibenzo[f,h]quinoxaline derivative is shown below (Structural formula (1) 00) to (131)). However, the present invention is not limited to these.

[0100] [ka]

[0101] [ka]

[0102] [ka]

[0103] [ka]

[0104] [ka]

[0105] [ka]

[0106] The dibenzo[f,h]quinoxaline derivative according to one embodiment of the present invention can be used as a By using it in a certain light-emitting element, a ... device, and an electronic device having high light-emitting efficiency and high reliability can be obtained. In addition, a light-emitting element, a light-emitting device, or a lighting device can be realized. , electronic devices, or lighting devices can be realized.

[0107] In addition, the dibenzo[f,h]quinoxaline derivatives represented by the general formulae (G0) to (G3) are Because it has electron-transporting and hole-transporting properties, it can be used as a host material in the light-emitting layer or as an electron transport material. It can be used as a hole transport layer or a positive transport layer. It can also be used as a light-emitting material in optical elements. The dibenzo[f,h]quinoxaline derivative represented by the formula: Since the dibenzofuran represented by the general formulas (G0) to (G3) is a novel compound having a wide range of uses, A light-emitting element including a zo[f,h]quinoxaline derivative is a light-emitting element of one embodiment of the present invention.

[0108] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiment modes. It is possible.

[0109] (Embodiment 3) In this embodiment, a light-emitting element according to one embodiment of the present invention is formed by sandwiching an EL layer between a charge generation layer and a A light emitting device having a structure having a plurality of light emitting elements (hereinafter, referred to as a tandem type light emitting device) will be described. As shown in FIG. 4A, the tandem light emitting element has a pair of electrodes (a first electrode 401 and A plurality of EL layers (first EL layer 402(1), second EL layer 402(2) and second electrode 404) are disposed between the first EL layer 402(3) and second EL layer 402(4). 2(2)).

[0110] In this embodiment, the first electrode 401 functions as an anode. The second electrode 404 functions as a cathode. The electrode 404 may have the same structure as that in the embodiment 1. The first EL layer 402(1) and the second EL layer 402(2) are the same as those in the first embodiment. The first layer may have a similar structure, or either of them may have a similar structure. The first EL layer 402(1) and the second EL layer 402(2) may have the same or different configurations. The configuration may be the same as that of the first embodiment. , in any one of the multiple EL layers (the first EL layer 402(1) and the second EL layer 402(2)). The dibenzo[f,h]quinoxaline derivative shown in Embodiment 2 can be used.

[0111] In addition, between the multiple EL layers (the first EL layer 402(1) and the second EL layer 402(2)), The charge generating layer 405 is provided between the first electrode 401 and the second electrode 402. When a voltage is applied to the electrode 404, electrons are injected into one EL layer and holes are injected into the other EL layer. In the present embodiment, the first electrode 401 is connected to the second electrode 40. When a voltage is applied so that the potential becomes higher than that of the first EL layer 404, the charge generating layer 405 emits light to the first EL layer 404. Electrons are injected into second EL layer 402(1) and holes are injected into second EL layer 402(2).

[0112] The charge generating layer 405 is transparent to visible light from the viewpoint of light extraction efficiency. (Specifically, it is preferable that the transmittance of visible light through the charge generating layer 405 is 40% or more.) In addition, the charge generating layer 405 has a lower electrical conductivity than the first electrode 401 and the second electrode 404. But it still works.

[0113] The charge generation layer 405 is formed by adding an electron acceptor to an organic compound having a high hole transporting property. Even if the structure is such that an electron donor is added to an organic compound with high electron transport properties, In addition, both of these configurations may be laminated.

[0114] In the case where an electron acceptor is added to an organic compound having high hole transport properties, Examples of organic compounds with high transport properties include NPB, TPD, TDATA, MTDATA, 4,4'-Bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenyla Aromatic amine compounds such as bis(amino)biphenyl (abbreviation: BSPB) can be used. The substances mentioned here are mainly 1×10 -6 cm 2 / Vs or more. However, if the organic compound has a higher hole transporting property than the electron transporting property, other substances than those mentioned above can be used. It's okay.

[0115] In addition, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroethylene is used as an electron acceptor. Examples of the fluorinated compounds include fluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. Further, transition metal oxides can be mentioned. Examples of the oxides of metals belonging to the group include vanadium oxide, niobium oxide, Tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, lanthanum oxide Molybdenum oxide is preferred because it has high electron-accepting properties. In particular, molybdenum oxide is stable in the atmosphere. This is preferable because it has low hygroscopicity and is easy to handle.

[0116] On the other hand, in the case where an electron donor is added to an organic compound having high electron transport properties, Examples of organic compounds with high electron transport properties include Alq3, Almq3, BeBq2, and B Metal complexes having a quinoline or benzoquinoline skeleton, such as Alq, can be used. In addition, oxazole-based compounds such as Zn(BOX)2 and Zn(BTZ)2, Metal complexes having azole-based ligands can also be used. However, PBD, OXD-7, TAZ, BPhen, BCP, etc. can also be used. The substances mentioned in are mainly 1×10 -6 cm 2 It is a material that has an electron mobility of 0.1V or more. In addition, any organic compound having a higher electron transporting property than a hole transporting property may be used other than the above. I don't.

[0117] The electron donor may be an alkali metal, an alkaline earth metal, a rare earth metal, or The metals belonging to the second and thirteenth groups of the periodic table and their oxides and carbonates are used. Specifically, lithium (Li), cesium (Cs), magnesium (Mg) , calcium (Ca), ytterbium (Yb), indium (In), lithium oxide, It is preferable to use cesium carbonate. The compound may be used as the electron donor.

[0118] In addition, the charge generating layer 405 is formed using the above-mentioned material, and thus the EL layer is laminated. In this case, the increase in the driving voltage can be suppressed.

[0119] In this embodiment mode, a light-emitting element having two EL layers has been described. In this way, n (n is 3 or more) EL layers (402(1) to 402(n)) are laminated. The present invention can be similarly applied to the light emitting device according to the present embodiment. In the case of a device having multiple EL layers between a pair of electrodes, By disposing the charge generating layers (405(1) to 405(n-1)), the current density is kept low. Since the current density can be kept low, it is possible to produce long-life elements. In addition, it can be applied to light-emitting devices, electronic devices, lighting devices, etc. that have a large light-emitting surface. In this case, the voltage drop due to the resistance of the electrode material can be reduced, making it possible to achieve uniform light emission over a large area. It becomes Noh.

[0120] In addition, by making the emission color of each EL layer different, the light-emitting device as a whole can have a desired color. For example, in a light-emitting element having two EL layers, the first By making the emission color of the first EL layer and the emission color of the second EL layer complementary to each other, It is also possible to obtain a light-emitting element that emits white light as a whole. This refers to the relationship between colors that become achromatic. In other words, when light of complementary colors is mixed with each other, Specifically, blue light is emitted from the first EL layer, and white light is emitted from the second EL layer. In this case, a combination in which yellow light emission (or orange light emission) can be obtained from the EL layer of the second electrode is possible. In this case, the blue and yellow (or orange) emissions are both the same fluorescent or phosphorescent emission. It is not necessary that the blue emission is fluorescent and the yellow emission (or orange emission) is phosphorescent. Furthermore, the optical path length in the light emitting element may be A laminated structure suitable for adjusting the emission wavelength (for example, yellow light is emitted from the first light-emitting layer and By using a structure in which blue light can be emitted from the cathode, the device characteristics can be further improved. is preferable.

[0121] The same applies to a light-emitting element having three EL layers. For example, the light-emitting element of the first EL layer The light color of the first EL layer is red, the light color of the second EL layer is green, and the light color of the third EL layer is blue. In some cases, the light emitting element as a whole can emit white light.

[0122] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiment modes. It is possible.

[0123] (Embodiment 4) In this embodiment, a colored layer (such as a color filter) is combined with the light-emitting element described in the first embodiment. In this embodiment, a light-emitting device in which the light-emitting element and the light-emitting diode are combined will be described. The configuration of the pixel section of the device will be described with reference to FIG.

[0124] In FIG. 5, a plurality of FETs (transistors) 502 are formed on a substrate 501. The ET 502 is electrically connected to each light emitting element (507R, 507G, 507B, 507Y). Specifically, each FET 502 is connected to a first electrode 503 which is a pixel electrode of a light-emitting element. In addition, a partition wall 5 is formed to fill the ends of the adjacent first electrodes 503. 04 is provided.

[0125] In addition, the first electrode 503 in this embodiment has a function as a reflective electrode. An EL layer 505 is formed on the first electrode 503, and a second The EL layer 505 is provided with a plurality of light-emitting diodes each emitting a single color light. The second electrode 510 is an electrode that functions as a semi-transmissive and semi-reflective electrode. be.

[0126] Each light-emitting element (507R, 507G, 507B, 507Y) emits a different light. Specifically, the light emitting element 507R is optically adjusted to obtain red light emission. In the region indicated by 506R, red light passes through the colored layer 508R in the direction of the arrow. The light emitting element 507G is optically adjusted to emit green light. In the region indicated by 506G, green light is emitted in the direction of the arrow through the colored layer 508G. The light emitting element 507B is optically adjusted to emit blue light. In the area indicated by 06B, blue light is emitted in the direction of the arrow through the colored layer 508B. The light emitting element 507Y is optically adjusted to emit yellow light. In the region indicated by Y, yellow light is emitted in the direction of the arrow through colored layer 508Y.

[0127] As shown in FIG. 5, each of the colored layers (508R, 508G, 508B, 508Y) is The optical elements (507R, 507G, 507B, 507Y) are disposed above the substrate 501. The color layers (508R, 508G) are provided on a transparent sealing substrate 511 placed on the substrate. , 508B, 508Y) are light emitting elements (507R, 507G) each of which emits a light of a respective color. , 507B, 507Y).

[0128] In addition, in order to fill the ends of the adjacent colored layers (508R, 508G, 508B, 508Y), A black layer (black matrix) 509 is provided. , 508G, 508B, 508Y) and the black layer 509 are overcoated with a transparent material. The insulating layer may be covered with a tungsten layer.

[0129] In the configuration described above, the structure in which light is emitted to the sealing substrate 511 side (top emission) is used. The light emitting device is a type (boiler type) that extracts light to the substrate 501 side where the FET is formed. The light emitting device may be a top-emission type. In the case of a cushion type light emitting device, a light-shielding substrate and a light-transmitting substrate are used as the substrate 501. However, in the case of a bottom emission type light emitting device, the substrate 501 can be A light-transmitting substrate must be used.

[0130] For example, in this specification, transistors and light-emitting elements are formed using various substrates. The type of the substrate is not limited to a specific one. For example, semiconductor substrates (such as single crystal substrates or silicon substrates), SOI substrates, glass substrates, English substrate, plastic substrate, metal substrate, stainless steel substrate, stainless steel Substrate with foil, Tungsten substrate, Substrate with tungsten foil, Flexible substrate Plates, laminated films, papers containing fibrous materials, or base films. Glass Examples of the substrate include barium borosilicate glass, aluminoborosilicate glass, or so Examples of flexible substrates, laminated films, and base films Examples of such materials include polyethylene terephthalate (PET), Polyethylene naphthalate (PEN), polyethersulfone (PES), polytetrafluoroethylene There are plastics such as fluoroethylene (PTFE) and acrylic. Synthetic resin, polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, etc. Films made of polyamide, polyimide, aramid, epoxy, etc. In particular, semiconductor substrates, single crystal substrates, and SO By manufacturing transistors using I substrates, etc., the characteristics, size, shape, etc. To manufacture transistors with small size, high current supply capability, and low variation in temperature. By configuring a circuit using such transistors, the power consumption of the circuit can be reduced. This allows for high circuit integration.

[0131] In addition, a flexible substrate is used as the substrate, and transistors and light-emitting elements are directly formed on the flexible substrate. Alternatively, a peeling layer may be provided between the substrate and the transistor or the like. After completing a part or all of the semiconductor device on it, it is separated from the substrate and transferred to another substrate. In this case, the transistors and the like are mounted on a substrate with poor heat resistance or a flexible substrate. The above-mentioned peeling layer may be formed, for example, of a tungsten film and a silicon oxide film. The laminated structure is made of an inorganic film and an organic resin film such as polyimide formed on a substrate. Composition etc. can be used.

[0132] That is, a transistor or a light-emitting element is formed on a certain substrate, and then the transistor or light-emitting element is formed on another substrate. The transistors and light-emitting elements may be transposed and disposed on a different substrate. An example of a substrate on which a transistor or a light emitting element is transferred is a substrate on which the above-mentioned transistors or the like are formed. In addition to the substrates that can be used, paper substrates, cellophane substrates, aramid film substrates, polyimide substrates, Midofilm substrate, stone substrate, wood substrate, fabric substrate (natural fibers (silk, cotton, hemp), synthetic fibers ( Nylon, polyurethane, polyester) or regenerated fiber (acetate, cupra, These include polyester, recycled polyester, leather substrates, and rubber substrates. By using this substrate, it is possible to form transistors with good characteristics and transistors with low power consumption. To form resistors, manufacture devices that are hard to break, provide heat resistance, and reduce weight or thickness. can be done.

[0133] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. It is possible to do so.

[0134] (Embodiment 5) In this embodiment, the dibenzo[f,h]quinoxaline derivative according to one embodiment of the present invention is used as an EL A light-emitting device having a light-emitting element used in a layer will be described.

[0135] The light emitting device may be a passive matrix light emitting device or an active matrix light emitting device. Note that the light-emitting device shown in this embodiment may be a light-emitting device having the same structure as the light-emitting device described in the other embodiment modes. Photonic elements can be applied.

[0136] In this embodiment mode, an active matrix light emitting device will be described with reference to FIG.

[0137] 6A is a top view showing a light emitting device, and FIG. 6B is a top view showing the light emitting device along the dashed line A in FIG. 1 is a cross-sectional view taken along line -A' of an active matrix light-emitting device according to an embodiment of the present invention. 6, a pixel section 602 and a driver circuit section (source line driver circuit) 603 are provided on an element substrate 601. 03 and driver circuit sections (gate line driver circuits) 604a and 604b. 02, the driver circuit section 603 and the driver circuit section 604 are attached to the element substrate by a sealant 605. It is sealed between 601 and a sealing substrate 606 .

[0138] In addition, on the element substrate 601, a driving circuit section 603, and driving circuit sections 604a and 604b are provided. An external signal (e.g. video signal, clock signal, start signal, or reset signal) A wiring 607 is provided for connecting an external input terminal for transmitting a signal or potential. Here, we set FPC (Flexible Print Circuit) 608 as the external input terminal. This is an example of a FPC. Note that only the FPC is shown here, but the FPC has a plug. A printed wiring board (PWB) may be attached. This includes not only the light emitting device itself, but also the state in which the FPC or PWB is attached to it. It shall be so.

[0139] Next, the cross-sectional structure will be described with reference to FIG. A driver circuit portion 603 which is a source line driver circuit and a pixel portion are formed. 6, a pixel portion 602 is shown.

[0140] The driving circuit section 603 is exemplified by a configuration in which a FET 609 and a FET 610 are combined. The driving circuit section 603 is a transistor of a single polarity (either N-type or P-type). The circuit may be formed of a circuit including an N-type transistor and a P-type transistor. In this embodiment, the driver circuit may be formed on a substrate. Although an integrated driver is shown, an external driver circuit can also be formed.

[0141] The pixel section 602 includes a switching FET 611, a current control FET 612, and a current control FET 613. A first electrode is electrically connected to the wiring (source electrode or drain electrode) of the control FET 612. The pixel electrode (anode) 613 is formed of a plurality of pixels. The pixel section 602 has two FFETs, a switching FET 611 and a current control FET 612. Although an example in which the pixel unit 602 is configured by ET has been described, the present invention is not limited to this. For example, The pixel portion 602 may be formed by combining three or more FETs and a capacitor element.

[0142] The FETs 609, 610, 611, and 612 are, for example, staggered or inverted staggered transistors. Transistors can be applied. Examples of semiconductor materials that can achieve this include Group 13 (gallium, etc.) semiconductors and Group 14 (silicon, etc.) Semiconductors such as silicon semiconductors, compound semiconductors, oxide semiconductors, and organic semiconductor materials can be used. The crystallinity of the semiconductor material is not particularly limited. For example, the semiconductor material may be an amorphous semiconductor film. In particular, FETs 609, 610, 611, and 612 can be made of crystalline semiconductor films. As the oxide semiconductor, for example, an In- Ga oxide, In-M-Zn oxide (M is Al, Ga, Y, Zr, La, Ce, or As the FETs 609, 610, 611, and 612, for example, The gap is 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. The off-state current of a transistor can be reduced by using an oxide semiconductor material.

[0143] An insulator 614 is formed to cover the end of the first electrode 613. The object 614 is formed by using a positive photosensitive acrylic resin. In this embodiment, the first electrode 613 is used as an anode.

[0144] In addition, the insulator 614 is designed to have a curved surface at the upper or lower end. By forming the shape of the insulator 614 as described above, the upper layer of the insulator 614 is The coating property of the formed film can be improved. For example, the material of the insulator 614 is Either a negative photosensitive resin or a positive photosensitive resin can be used. Not only organic compounds but also inorganic compounds such as silicon oxide, silicon oxynitride, silicon nitride, etc. Cone, etc. can be used.

[0145] An EL layer 615 and a second electrode (cathode) 616 are laminated on a first electrode (anode) 613. The EL layer 615 is provided with at least a light-emitting layer. In addition to the light-emitting layer, 5 may also include a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a charge generation layer, etc. can be provided as appropriate.

[0146] The first electrode (anode) 613, the EL layer 615, and the second electrode (cathode) 616 are laminated. The light emitting element 617 is formed by the structure. The material for the second electrode (cathode) 616 is the same as that shown in the embodiment 2. Although not shown here, the second electrode (cathode) 616 is an external input terminal. The FPC 608 is electrically connected to the FPC 608.

[0147] In addition, although only one light emitting element 617 is shown in the cross-sectional view shown in FIG. 02, a plurality of light emitting elements are arranged in a matrix. 2, light-emitting elements capable of emitting three kinds of light (R, G, B) are selectively formed, and It is possible to form a light-emitting device capable of displaying three colors (R, G, B). In addition to the light-emitting element from which light is obtained, for example, white (W), yellow (Y), magenta (M For example, a light-emitting element that can emit light of three colors (R, A light-emitting element capable of emitting the above-mentioned several types of light is added to a light-emitting element capable of emitting the light of G and B. This can improve color purity and reduce power consumption. By combining it with a filter, a light emitting device capable of full color display may be formed. In addition, by combining it with quantum dots, the light-emitting device has improved light-emitting efficiency and reduced power consumption. It may also be placed.

[0148] Furthermore, a sealing substrate 606 is bonded to the element substrate 601 with a sealant 605, A space 618 surrounded by the element substrate 601, the sealing substrate 606, and the sealant 605 contains light-emitting elements. The space 618 is filled with an inert gas (such as nitrogen or argon). In addition to the case where the cavity is filled with a gas such as argon, a configuration where the cavity is filled with a sealant 605 is also included.

[0149] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is desirable that these materials are as impermeable to moisture and oxygen as possible. Materials used for the sealing substrate 606 and the element substrate 601 include glass substrates, quartz substrates, and FRP. (Fiber-Reinforced Plastics), PVF (Polyvinyl Flora A plastic substrate made of, for example, polyester or acrylic can be used. When glass frit is used as the sealing material, the element substrate 601 and the The sealing substrate 606 is preferably a glass substrate.

[0150] In this manner, an active matrix light emitting device can be obtained.

[0151] Note that the structure shown in this embodiment mode may be used in appropriate combination with structures shown in other embodiment modes. It is possible.

[0152] (Embodiment 6) In this embodiment, various electronic devices are completed using a light-emitting device which is one embodiment of the present invention. An example of this will be described with reference to FIG.

[0153] As an example of an electronic device to which a light-emitting device is applied, a television set (television or television (also called television receivers), computer monitors, digital cameras, digital video Cameras such as cameras, digital photo frames, mobile phones (mobile phones, mobile phone devices, etc.) (also called "game consoles"), portable game machines, personal digital assistants, audio playback devices, pachinko machines and other large game machines Specific examples of these electronic devices are shown in Figure 7.

[0154] FIG. 7A shows an example of a television device. The television device 7100 is A display unit 7103 is built into the body 7101. The display unit 7103 displays images. It is possible to use a touch panel (input / output device) equipped with a touch sensor (input device). Note that the light-emitting device which is one embodiment of the present invention can be used for the display portion 7103. In addition, a configuration in which the housing 7101 is supported by a stand 7105 is shown here. There are.

[0155] 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 the remote control operation device 7110. The channel and volume can be controlled by the 7109, and the display 7103 shows In addition, the remote control unit 7110 can control the video. A display unit 7107 for displaying information output from 7110 may be provided.

[0156] The television device 7100 includes a receiver and a modem. It is possible to receive more general television broadcasts, and furthermore, to receive them by wire or wirelessly via a modem. By connecting to a communication network, It is also possible to communicate information between followers and recipients, or between recipients themselves.

[0157] FIG. 7B shows a computer, which includes a main body 7201, a housing 7202, a display unit 7203, and a keyboard. It includes a board 7204, an external connection port 7205, a pointing device 7206, and the like. Note that the computer uses the light-emitting device according to one embodiment of the present invention for the display portion 7203. The display panel 7203 can be manufactured by using a touch sensor (an input device). ) may be mounted on a touch panel (input / output device).

[0158] FIG. 7C shows a smart watch. The smart watch includes a housing 7302, a display panel 7304, and an operation button. The connector 7311, 7312, a connection terminal 7313, a band 7321, a clasp 7322, etc. do.

[0159] A display panel 7304 mounted on a housing 7302 that also serves as a bezel has a non-rectangular display area. The display panel 7304 displays an icon 7305 representing the time, other icons, The display portion 7304 can display a touch sensor (input device). The present invention may be applied to a touch panel (input / output device) equipped with a touch panel.

[0160] The smartwatch shown in FIG. 7C can have various functions. For example, , the function to display various information (still images, videos, text images, etc.) on the display unit, Functions such as displaying calendars, dates, or times, and various software (programs) The function of controlling processing by the wireless communication function, It has a function to connect to a data network, and a wireless communication function to transmit or receive various data. The function of reading out the program or data recorded on the recording medium and displaying it on the display unit. It may have the function of

[0161] In addition, a speaker, a sensor (force, displacement, position, velocity, acceleration, angular velocity) degree, rotation speed, distance, light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, current, Includes functions to measure pressure, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays. The smart watch may have a light emitting device, a microphone, etc. The display panel 7304 can be manufactured by using the same.

[0162] FIG. 7(D) shows an example of a mobile phone (including a smartphone). Mobile phone 7 400 is a housing 7401, a display unit 7402, a microphone 7406, a speaker 7405, a camera The device is equipped with a camera 7407, an external connection unit 7404, and an operation button 7403. When a light-emitting device is manufactured by forming a light-emitting element according to one embodiment of the present invention on a flexible substrate, This can be applied to a display portion 7402 having a curved surface as shown in FIG.

[0163] In a mobile phone 7400 shown in FIG. 7D, information is displayed by touching a display portion 7402 with a finger or the like. You can also make a call or write an email by This can be done by touching the display portion 7402 with a finger or the like.

[0164] The screen of the display unit 7402 has three main modes. The first is a display mode that is mainly used for displaying images. The first mode is a display mode, the second is an input mode for inputting information such as characters, and the third mode is a display mode. This is a display + input mode that combines the display mode and the input mode.

[0165] For example, when making a call or composing an e-mail, the display unit 7402 is used to input characters. The main character input mode is to input characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402. It is nice.

[0166] In addition, a detection device such as a gyro sensor or an acceleration sensor is provided inside the mobile phone 7400. By this, the orientation of the mobile phone 7400 (vertical or horizontal) is determined, and the screen display of the display unit 7402 is can be made to switch automatically.

[0167] The screen mode can be changed by touching the display portion 7402 or by operating the housing 7401. The type of image displayed on the display unit 7402 can be changed by operating the button 7403. For example, the image signal to be displayed on the display unit may be changed by If the data is text data, the mode switches to input mode.

[0168] In the input mode, the optical sensor of the display unit 7402 detects a signal and displays If there is no input by touch operation of the part 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.

[0169] The display portion 7402 can also function as an image sensor. By touching the palm or fingers of the user on the sensor 02 and capturing an image of the palm print or fingerprint, the user can be authenticated. In addition, a backlight that emits near-infrared light to the display unit or a sensing light source that emits near-infrared light By using this, it is possible to image finger veins, palm veins, etc.

[0170] Furthermore, as another configuration of a mobile phone (including a smartphone), FIG. 7(D'-1) and FIG. The present invention can also be applied to a mobile phone having a structure such as that shown in FIG. 7(D'-2).

[0171] In addition, when the structure is as shown in FIG. 7(D'-1) or FIG. 7(D'-2), character information and Image information, etc., is stored on the first surfaces 7501(1) and 7501(2) of the housings 7500(1) and 7500(2). (2), but can also be displayed on the second surfaces 7502(1) and 7502(2). With this structure, the mobile phone can be stored in a breast pocket without Uses text and image information displayed on pages 7502(1) and 7502(2) on the second page This can be easily verified by the person in charge.

[0172] 8(A) to (C) show a foldable mobile information terminal 9310. 8(B) shows the portable information terminal 9310 in an unfolded or folded state. The mobile information terminal 9310 is in the process of changing from one folded state to the other. FIG. 9C) shows the portable information terminal 9310 in a folded state. When folded, it is highly portable, and when unfolded, it has a seamless, large display area for easy viewing. It has excellent visibility of the information displayed.

[0173] The display panel 9311 is supported by three housings 9315 connected by hinges 9313. The display panel 9311 is a touch panel equipped with a touch sensor (input device). The display panel 9311 may be a display panel (input / output device). The portable information terminal 9310 is in an unfolded state by bending the two housings 9315. The light-emitting device according to one embodiment of the present invention can be reversibly transformed from a folded state to a folded state. It can be used for a display panel 9311. The display area of ​​the display panel 9311 is a folding type. This is a display area located on the side of the portable information terminal 9310 in the folded state. Display information icons and frequently used app and program shortcuts This allows you to smoothly check information and launch apps, etc.

[0174] In this manner, an electronic device can be obtained by using the light-emitting device which is one embodiment of the present invention. In addition, the electronic devices that can be used are not limited to those shown in this embodiment, but can be used in any field. The present invention can be applied to electronic devices.

[0175] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiment modes. It is possible.

[0176] (Embodiment 7) In this embodiment, an example of a lighting device to which a light-emitting device according to one embodiment of the present invention is applied will be described. This will be explained using FIG.

[0177] FIG. 9 shows an example in which the light emitting device is used as an indoor lighting device 8001. It is also possible to make a large-area lighting device because it is possible to make a large-area lighting device. By using a housing having such a curved surface, the light emitting area has a curved surface. A lighting device 8002 can also be formed. The element is thin film, and the design of the housing has a high degree of freedom. Furthermore, a large lighting device 8003 can be provided on the wall of the room. It's okay to think so.

[0178] In addition, by using a light-emitting device on the surface of a table, a lighting device having a function as a table can be provided. The light emitting device can be used as a light emitting device 8004. This makes it possible to provide a lighting device that also functions as furniture.

[0179] As described above, various lighting devices using the light-emitting device can be obtained. is included in one aspect of the present invention.

[0180] The structure shown in this embodiment mode may be used in appropriate combination with structures shown in other embodiment modes. It is possible. EXAMPLES

[0181] <Synthesis Example 1> In this example, a synthesis method according to one embodiment of the present invention was carried out using 2-{4-[3-(N-phenyl -9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzyl Synthesis of zo[f,h]quinoxaline (abbreviation: 2PCCzPDBq) (structural formula (100)) The structure of 2PCCzPDBq is shown below.

[0182] [ka]

[0183] <Synthesis of 2PCCzPDBq> First, 1.0 g (2.8 mg) of 2-(4-chlorophenyl)dibenzo[f,h]quinoxaline mol), 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole 1.1g (2.8mmol), sodium tert-butoxide 0.54g (5.6m mol), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S- Add 23 mg (0.10 mmol) of phosphate to a 200 mL three-neck flask and mix. The flask was purged with nitrogen. 14 mL of mesitylene was added to the mixture, and the flask was placed under reduced pressure. The mixture was then degassed by stirring.

[0184] Next, bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd( dba)2) 16 mg (0.028 mmol) was added. This mixture was stirred for 15 min under a nitrogen stream. After stirring at 0°C for 5 hours, a solid precipitated. The precipitated solid was collected by suction filtration. The collected solid was dissolved in about 400 mL of hot toluene, and the solution was filtered through Celite and aluminum. The filtrate was concentrated and the solid was recrystallized from toluene. As a result, 1.6 g of the desired yellow powder was obtained in a yield of 80%.

[0185] The resulting yellow powdery solid (1.4 g) was purified by train sublimation. The sublimation purification conditions were a pressure of 3.8 Pa and an argon gas flow rate of 10 mL / min. After purification by sublimation, the yellow glassy solid of 2PCCzPDBq was obtained. The compound was obtained in an amount of 1.1 g and a yield of 79%. The synthetic scheme for this step is shown in (a-1) below.

[0186] [ka]

[0187] Nuclear magnetic resonance spectroscopy of the yellow powdery solid obtained in the above step ( 1 Analysis by H-NMR The results are shown below. 1 The H-NMR charts are shown in Figures 10(A) and 10(B). 10(B) is the horizontal axis (δ) of Fig. 10(A) from 7.0(ppm) to 10(ppm). From this, in the above step, (Structural formula (100)) was obtained.

[0188] δ=7.32(t,J=5.7Hz,1H),7.37(t,J=8.0Hz,1H), 7.43-7.53(m,5H),7.58-7.66(m,6H),7.72-7.8 9(m,8H),8.25(d,J=7.4Hz,1H),8.30(d,J=8.1H z,1H),8.44(d,J=7.5Hz,1H),8.50(d,J=5.4Hz, 2H),8.64-8.67(m,3H),9.25(d,J=8.0Hz,1H),9 .37(d,J=6.3Hz,1H),9.47(s,1H).

[0189] Next, the absorption spectrum and emission spectrum of the toluene solution of 2PCCzPDBq are shown in Figure 11. The absorption and emission spectra of the thin film are shown in Fig. 12. A visible-light spectrophotometer (V550, manufactured by JASCO Corporation) was used. The torr was measured by placing a toluene solution of 2PCCzPDBq in a quartz cell. The spectrum was measured using a sample prepared by evaporating 2PCCzPDBq onto a quartz substrate. The absorption spectrum of the toluene solution was measured by putting only toluene in a quartz cell. The absorption spectrum of the thin film is shown with the absorption spectrum of the quartz substrate subtracted. The absorption spectrum after spectrum subtraction is shown.

[0190] As shown in Figure 11, the toluene solution of 2PCCzPDBq has absorption peaks around 305 nm and 385 nm. A peak was observed in the emission wavelength at 450 nm (excitation wavelength 305 nm). From Figure 12, the thin film of 2PCCzPDBq is 209 nm, 258 nm, 307 nm, and 336 nm. Absorption peaks are seen at around 396 nm and 396 nm, and the emission wavelength peak is 502 nm (excitation wavelength The length was 396 nm. EXAMPLES

[0191] <Synthesis Example 2> In this example, a synthesis method according to one embodiment of the present invention was carried out using 2-{3-[3-(N-phenyl -9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzyl Synthesis of zo[f,h]quinoxaline (abbreviation 2mPCCzPDBq) (structural formula (101)) The structure of 2mPCCzPDBq is shown below.

[0192] [ka]

[0193] <Synthesis of 2mPCCzPDBq> First, 1.7 g (5.0 mg) of 2-(3-chlorophenyl)dibenzo[f,h]quinoxaline was mol), 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole 2.0g (5.0mmol), sodium tert-butoxide 0.96g (10mmol) ol), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (SP Add 41 mg (0.10 mmol) of HOs to a 200 mL three-neck flask, mix, and The atmosphere was replaced with nitrogen. 25 mL of mesitylene was added to this mixture, and the inside of the flask was placed under reduced pressure. The mixture was degassed by stirring.

[0194] Next, bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd( dba)2) (29 mg, 0.050 mmol) was added to the mixture. After stirring at 0°C for 5 hours, a solid precipitated. The precipitated solid was collected by suction filtration. The collected solid was dissolved in about 400 mL of hot toluene, and the solution was filtered through Celite and aluminum. The filtrate was concentrated and the solid was recrystallized from toluene. As a result, 2.8 g of a yellow powder was obtained in a yield of 79%.

[0195] The resulting yellow powdery solid (2.2 g) was purified by train sublimation. The conditions for the sublimation purification were a pressure of 2.5 Pa and an argon gas flow rate of 10 mL / min. After purification by sublimation, a yellow glassy solid of 2mPCCzPDBq was obtained. The compound was obtained in an amount of 1.2 g with a recovery rate of 55%. The synthetic scheme for this step is shown in (b-1) below. .

[0196] [ka]

[0197] Nuclear magnetic resonance spectroscopy of the yellow powdery solid obtained in the above step ( 1 Analysis by H-NMR The results are shown below. 1 The H-NMR charts are shown in Figures 13(A) and 13(B). 13(B) shows the horizontal axis (δ) of Fig. 13(A) changed from 7.0(ppm) to 10(ppm). This is an enlarged view of the range of 2-{3-[3-( N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl)phenyl nyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) (structural formula (10 It was found that 1)) was obtained.

[0198] 1 H NMR(CDCl3,500MHz):δ(ppm)=7.31-7.54(m, 7H),7.58-7.67(m,6H),7.73-7.90(m,8H),8.25 (d,J=8.0Hz,1H),8.30(d,J=8.1Hz,1H),8.45(d ,J=6.3Hz,1H),8.49(d,J=3.7Hz,2H),8.65-8.6 8(m,3H),9.25(d,J=2.0Hz,1H),9.37(d,J=6.9H z,1H),9.48(s,1H).

[0199] Next, the absorption spectrum and emission spectrum of 2mPCCzPDBq in toluene are shown in Fig. 1. The absorption and emission spectra of the thin film are shown in Fig. 15. An ultraviolet-visible spectrophotometer (V550, manufactured by JASCO Corporation) was used. The spectra were measured by placing a toluene solution of 2mPCCzPDBq in a quartz cell. The spectrum of the film was measured by preparing a sample by evaporating 2mPCCzPDBq onto a quartz substrate. The absorption spectrum of the toluene solution was measured by putting only toluene in the quartz cell. The absorption spectrum of the thin film is shown with the absorption spectrum of the quartz substrate subtracted. The absorption spectrum from which the absorption spectrum of

[0200] As shown in Figure 14, the toluene solution of 2mPCCzPDBq absorbs around 305 nm and 374 nm. A peak was observed, and the emission wavelength peak was 480 nm (excitation wavelength 305 nm). ,From Figure 15, the thin film of 2mPCCzPDBq is 208 nm, 257 nm, 308 nm, and 36 Absorption peaks were observed at around 1 nm and 379 nm, and the emission wavelength peak was 515 nm (excitation wavelength). The excitation wavelength was 380 nm. EXAMPLES

[0201] <Synthesis Example 3> In this example, a synthesis method according to one embodiment of the present invention was carried out using 2-{4-[2-(N-phenyl -9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzyl Zo[f,h]quinoxaline (abbreviation: 2PCCzPDBq-02) (structural formula (102)) The synthesis method is explained below. The structure of 2PCCzPDBq-02 is shown below.

[0202] [ka]

[0203] <Synthesis of 2PCCzPDBq-02> First, 1.4 g (4.2 m) of 2-(4-chlorophenyl)dibenzo[f,h]quinoxaline mol), 2-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole 1.7g (4.2mmol), sodium tert-butoxide 0.81g (8.4m mol), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S- Add 34 mg (0.10 mmol) of phosphatidylcholine to a 200 mL three-neck flask and mix. The flask was purged with nitrogen. 21 mL of mesitylene was added to the mixture, and the flask was placed under reduced pressure. The mixture was then degassed by stirring.

[0204] Next, bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd( dba)2) (24 mg, 0.042 mmol) was added. This mixture was stirred for 15 min under a nitrogen stream. After stirring at 0°C for 5 hours, a solid precipitated. The precipitated solid was collected by suction filtration. The collected solid was dissolved in about 400 mL of hot toluene, and the solution was filtered through Celite and aluminum. The filtrate was concentrated and the solid was recrystallized from toluene. As a result, 2.5 g of a yellow powder was obtained in a yield of 84%.

[0205] The resulting yellow powdery solid (2.0 g) was purified by train sublimation. The conditions for sublimation purification were a pressure of 3.7 Pa and an argon gas flow rate of 10 mL / min. After sublimation purification, the yellow glass of 2PCCzPDBq-02 was obtained. The solid was obtained in an amount of 1.7 g with a recovery rate of 85%. The synthesis scheme for this step is shown in (c-1) below. show.

[0206] [ka]

[0207] Nuclear magnetic resonance spectroscopy of the yellow powdery solid obtained in the above step ( 1 Analysis by H-NMR The results are shown below. 1 The H-NMR charts are shown in Figures 16(A) and 16(B). 16(B) shows the horizontal axis (δ) of Fig. 16(A) changed from 7.0(ppm) to 10(ppm). This is an enlarged view of the range of 2-{4-[2-( N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl)phenyl nyl}dibenzo[f,h]quinoxaline (abbreviation: 2PCCzPDBq-02) (structural formula ( 102)) was obtained.

[0208] δ=7.25-7.48(m,7H),7.71-7.75(m,2H),7.71-7 .75(m,5H),7.91(d,J=8.6Hz,2H),8.21(d,J=7. 4Hz,1H),8.26(d,J=8.0Hz,2H),8.42(sd,J=1.7 Hz,2H),8.63-8.69(m,4H),9.27(d,J=8.0Hz,1H ),9.46(d,J=6.3Hz,1H),9.51(s,1H).

[0209] Next, the absorption and emission spectra of the toluene solution of 2PCCzPDBq-02 were The absorption spectrum and emission spectrum of the thin film are shown in Figure 17 and Figure 18, respectively. A UV-visible spectrophotometer (V550, manufactured by JASCO Corporation) was used for the analysis. The spectrum was measured by placing a toluene solution of 2PCCzPDBq-02 in a quartz cell. The spectrum of the thin film was obtained by depositing 2PCCzPDBq-02 on a quartz substrate. The absorption spectrum of the toluene solution was measured by putting only toluene in the quartz cell. The absorption spectrum of the thin film is shown in Fig. 1. The absorption spectrum of the thin film is shown in Fig. 1. The absorption spectrum is shown after subtracting the absorption spectrum of the substrate.

[0210] As shown in Figure 17, the toluene solution of 2PCCzPDBq-02 has peaks at around 323 nm and 381 nm. An absorption peak was observed, and the emission wavelength peak was 421 nm (excitation wavelength 320 nm). In addition, from Figure 18, the thin film of 2PCCzPDBq-02 is 209 nm, 257 nm, and 311 nm. Absorption peaks are seen at 326 nm, 351 nm, and 389 nm, and the emission wavelength peaks are The excitation wavelength was 473 nm (excitation wavelength 396 nm). EXAMPLES

[0211] <Synthesis Example 4> In this example, 2-{3-[2-(N-phenyl-9H-carbazone]-1,2-diphenyl-2,4-diphenyl-1H-phenyl-2H- ... (3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quino Synthesis of xaline (abbreviation 2mPCCzPDBq-02) (structural formula (103)) The structure of 2mPCCzPDBq-02 is shown below.

[0212] [ka]

[0213] <Synthesis of 2mPCCzPDBq-02> First, 1.7 g (5.0 mg) of 2-(3-chlorophenyl)dibenzo[f,h]quinoxaline was mol), 2-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole 2.0g (5.0mmol), sodium tert-butoxide 0.96g (10mmol) ol), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (SP Add 41 mg (0.10 mmol) of HOs to a 200 mL three-neck flask, mix, and The atmosphere was replaced with nitrogen. 25 mL of mesitylene was added to this mixture, and the inside of the flask was placed under reduced pressure. The mixture was degassed by stirring.

[0214] Next, bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd( dba)2) (29 mg, 0.050 mmol) was added to the mixture. After stirring at 0°C for 4 hours, a solid precipitated. The precipitated solid was collected by suction filtration. The collected solid was dissolved in about 400 mL of hot toluene, and the solution was filtered through Celite and aluminum. The mixture was filtered through a laminate of sodium hydroxide and Florisil by suction. The filtrate was concentrated to give a solid. The residue was recrystallized from toluene to obtain 3.1 g of a white powder in a yield of 87%.

[0215] The resulting white powdery solid (3.0 g) was purified by train sublimation. The conditions for sublimation purification were a pressure of 10 Pa and an argon gas flow rate of 5.0 mL / min. After purification by sublimation, the yellow glass of 2mPCCzPDBq-02 was A powdery solid was obtained (2.0 g, 65% recovery). The synthesis scheme for this step is shown below (d-1). As shown in.

[0216] [ka]

[0217] The nuclear magnetic resonance spectroscopy of the white powdery solid obtained in the above step ( 1 Analysis by H-NMR The results are shown below. 1 The H-NMR charts are shown in Figures 19(A) and 19(B). 19(B) shows the horizontal axis (δ) of Fig. 19(A) changed from 7.0(ppm) to 10(ppm). This is an enlarged view of the range of 2mPCCzPDB It was found that q-02 (structural formula (103)) was obtained.

[0218] 1 H NMR (DMSO-d 6 ,500MHz):δ(ppm)=7.17(t,J1= 7.5Hz, 1H), 7.31-7.39(m, 4H), 7.47-7.52(m, 2H) ),7.56-7.57(m,3H),7.63-7.66(m,3H),7.75-7 .92(m,7H),7.98(t,J1=2.5Hz,1H),8.19(d,J1= 7.5Hz,1H),8.30(d,J1=7.5Hz,1H),8.37(d,J1= 8.0Hz,1H),8.54(sd,J1=1.5Hz,1H),8.62(d,J1 =8.0Hz,1H),8.79-8.82(m,3H),9.19(d,J1=8.0 Hz,1H),9.25(d,J1=9.0Hz,1H),9.75(s,1H).

[0219] Next, the absorption and emission spectra of 2mPCCzPDBq-02 in toluene The absorption spectrum and emission spectrum of the thin film are shown in Figure 20 and Figure 21, respectively. The measurement was performed using an ultraviolet-visible spectrophotometer (V550, manufactured by JASCO Corporation). The spectrum was measured by placing a toluene solution of 2mPCCzPDBq-02 in a quartz cell. The spectrum of the thin film was obtained by evaporating 2mPCCzPDBq-02 onto a quartz substrate. The absorption spectrum of the toluene solution was measured by placing toluene in a quartz cell. The absorption spectrum after subtracting the absorption spectrum measured with the filter is shown in Fig. The absorption spectrum shown is the absorption spectrum from which the absorption spectrum of the quartz substrate has been subtracted.

[0220] As shown in Figure 20, the toluene solution of 2mPCCzPDBq-02 is irradiated at 281 nm, 305 nm, and 3 Absorption peaks are seen at around 19 nm and 374 nm, and the emission wavelength peak is 389 nm. and 410 nm. Also, from Figure 21, the thin film of 2mPCCzPDBq-02 was 209 Absorption peaks at 257nm, 309nm, 327nm, 354nm, and 386nm A peak was observed in the emission wavelength at 484 nm (excitation wavelength 381 nm). EXAMPLES

[0221] In this example, a development process was carried out using a dibenzo[f,h]quinoxaline derivative which is one embodiment of the present invention. The optical element 1, the light-emitting element 2, and the comparative light-emitting element 3 were fabricated. The details will be explained with reference to Fig. 22. The chemical formulas of the materials used in this example are shown below.

[0222] [ka]

[0223] [ka]

[0224] <Fabrication of Light-Emitting Element 1, Light-Emitting Element 2, and Comparative Light-Emitting Element 3> First, indium tin oxide containing silicon oxide (ITSO) is deposited on a glass substrate 1100. A film was formed by a sputtering method to form a first electrode 1101 that functions as an anode. The film thickness was 110 nm and the electrode area was 2 mm × 2 mm.

[0225] Next, in order to form the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3 on the substrate 1100, As a pretreatment, the substrate surface was washed with water, baked at 200°C for 1 hour, and then UV ozone treatment was performed. This was done for 370 seconds.

[0226] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. After vacuum baking at 170° C. for 30 minutes in the heating chamber of the device, the substrate 1100 is It was left to cool for about 0 minutes.

[0227] Next, the substrate 1100 is vacuum-deposited so that the surface on which the first electrode 1101 is formed faces downward. The EL layer 11 was fixed to a holder provided in the device. 02, a hole injection layer 1111, a hole transport layer 1112, a light emitting layer 1113, and an electron transport layer A case where a layer 1114 and an electron injection layer 1115 are formed in this order will be described.

[0228] The vacuum deposition equipment was -4 After reducing the pressure to 100 Pa, 1,3,5-tri(dibenzothiophene 4-yl)-benzene (abbreviation: DBT3P-II) and molybdenum oxide, The first electrode was formed by co-evaporating the first electrode and the second electrode in a ratio of 4:2 (mass ratio). A hole injection layer 1111 was formed on the electrode 1101. The thickness of the layer was set to 20 nm. is a deposition method in which different substances are evaporated simultaneously from different evaporation sources.

[0229] Next, 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) was evaporated to a thickness of 20 nm to form a hole transport layer 1112. .

[0230] Next, a light-emitting layer 1113 was formed on the hole-transporting layer 1112. 3-[2-(N-phenyl-9H-carbazol-3-yl)-9H-carbazole-9 -yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq-0 2 (Structural formula (103))), N-(1,1'-biphenyl-4-yl)-N-[4-(9 -phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H- PCBBiF, (acetylacetonato)bis(6-tetraacetate) rt-Butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tB uppm)2(acac)]), 2mPCCzPDBq-02:PCBBiF:[Ir (tBuppm)2(acac)] = 0.7:0.3:0.05 (mass ratio) After deposition and forming a film with a thickness of 20 nm, 2mPCCzPDBq-02:PCBBiF:[ Ir(tBuppm)2(acac)] = 0.8:0.2:0.05 (mass ratio) The light-emitting layer 1113 having a laminated structure was formed by co-evaporating the four layers of the luminescent layer 1113 to a thickness of 20 nm. The film was formed to a thickness of 0 nm.

[0231] In the case of light-emitting element 2, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl )-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation :2mPCCzPDBq (Structural formula (101))), PCBBiF, [Ir(tBuppm )2(acac)], 2mPCCzPDBq:PCBBiF:[Ir(tBuppm) 2(acac)] = 0.7:0.3:0.05 (mass ratio), After forming the film with a thickness of 2mPCCzPDBq:PCBBiF:[Ir(tBuppm)2 (acac)] = 0.8:0.2:0.05 (mass ratio), and The light-emitting layer 1113 having a laminated structure was formed to a thickness of 40 nm. .

[0232] In the case of the comparative light-emitting element 3, 2-[3'-(dibenzothiophene-4-yl)biphenyl] nyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II ), PCBBiF, [Ir(tBuppm)2(acac)], 2mDBTBPDBq -II:PCBBiF:[Ir(tBuppm)2(acac)]=0.7:0.3:0 0.05 (mass ratio), and then a 20 nm thick film was formed. Bq-II:PCBBiF:[Ir(tBuppm)2(acac)]=0.8:0.2 0.05 (mass ratio) and a thickness of 20 nm was formed to form a laminate structure. The light emitting layer 1113 having this structure was formed to a thickness of 40 nm.

[0233] Next, in the case of the light-emitting element 1, 2mPCCzPDBq-02 was deposited on the light-emitting layer 1113 at a thickness of 20 nm. After the deposition, bathophenanthroline (abbreviation: Bphen) was deposited at 10 nm. In the case of the light-emitting element 2, a 2 μm thick film was formed on the light-emitting layer 1113. After depositing 20 nm of PCCzPDBq, bathophenanthroline (abbreviation: Bphen) was An electron transport layer 1114 was formed by vapor deposition of 10 nm. In the case of the luminescent layer 1113, 20 nm of 2mDBTBPDBq-II was deposited on the luminescent layer 1113, and then the By depositing phenanthroline (abbreviation: Bphen) at 10 nm, an electron transport layer 111 4 was formed.

[0234] Furthermore, lithium fluoride is deposited at 1 nm on the electron transport layer 1114 to inject electrons. A layer 1115 was formed.

[0235] Finally, aluminum was evaporated onto the electron injection layer 1115 to a thickness of 200 nm. A second electrode 1103 serving as a cathode was formed, and the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element were In the above-mentioned deposition process, the deposition was all performed by resistance heating.

[0236] The device structures of the thus obtained light-emitting element 1, light-emitting element 2, and comparative light-emitting element 3 are shown in Table 1. show.

[0237] [Table 1]

[0238] The fabricated light-emitting element 1, light-emitting element 2, and comparative light-emitting element 3 were placed in a container so as not to be exposed to the air. The device was sealed in a glove box with a nitrogen atmosphere (specifically, the device was sealed in a nitrogen atmosphere). The specimen was then coated with a coating of adhesive, UV-treated, and heat-treated at 80°C for 1 hour.

[0239] <Operation characteristics of light-emitting element 1, light-emitting element 2, and comparative light-emitting element 3> The operating characteristics of the fabricated light-emitting element 1, light-emitting element 2, and comparative light-emitting element 3 were measured. The measurements were carried out at room temperature (atmosphere maintained at 25°C). The results are shown in Figures 23 to 26. show.

[0240] Also, 1000cd / m 2 Light-emitting element 1, light-emitting element 2, and comparative light-emitting element 3 in the vicinity The main initial characteristic values ​​are shown in Table 2 below.

[0241] [Table 2]

[0242] In addition, the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3 were each subjected to a current of 2.5 mA / cm 2 Current density of FIG. 27 shows the emission spectrum when a current was applied. The optical element 2 and the comparative light-emitting element 3 both have an optical constant of [Ir(tBuppm)2(acac)] The spectrum showed a peak at around 546 nm, which was due to

[0243] The results of reliability tests on the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3 are shown in FIG. In FIG. 28(A), the vertical axis is the normalized value when the initial luminance is set to 100%. The horizontal axis indicates the brightness (%) and the horizontal axis indicates the operation time (h) of the element. Note that the reliability test was performed on the initial brightness 5000cd / m 2 The current density was set to constant, and the light-emitting elements 1, 2, and The comparative light-emitting element 3 was driven.

[0244] As a result, a light-emitting device 1 using 2mPCCzPDBq-02, which is one embodiment of the present invention, and Light-emitting element 2 using 2mPCCzPDBq is compared with 2mDBTBPDBq-II. It was found that this light-emitting element had higher reliability and a longer lifetime than Light-emitting Element 3.

[0245] The results of measuring the amount of voltage change during a reliability test are shown in FIG. 28(B). The vertical axis is the voltage change The horizontal axis indicates the amount of light emitted (V), and the horizontal axis indicates the operation time of the element (h). The voltage rise of the element 1 and the light-emitting element 2 when driven at a constant current is smaller than that of the comparative light-emitting element 3. For example, when we look at the amount of voltage rise after about 500 hours of operation, the comparative light-emitting element 3 The light-emitting element 1 has a voltage of about 0.05 V, and the light-emitting element 2 has a voltage of about 0.0 2 V. In other words, the voltage rise of the light-emitting element 1 is about half that of the comparative light-emitting element 3. The voltage rise of element 2 was suppressed to about one-fourth, which is a remarkable effect.

[0246] In addition, 2mPCCzPDBq-02, 2mPCCzPDBq, 2mDBTBPDBq-I All of these dibenzoquinoxaline compounds form exciplexes with PCBBiF. The mixed films of PCBBiF and dibenzoquinoxaline compounds were all more effective than the single films of PCBBiF and dibenzoquinoxaline compounds. (Because it emits yellow-green light with a longer wavelength than the BiF monolayer.) 2, 2mPCCzPDBq, 2mDBTBPDBq-II, and PCBBiF HOM The O levels are -5.69 eV, -5.63 eV, -6.22 eV, and -5.36 eV, respectively. The HOMO level was calculated from cyclic voltammetry (CV) measurements. .

[0247] From the HOMO level measurement results, ΔE HOMO was calculated. The results are summarized in Table 3.

[0248] [Table 3]

[0249] From this result, ΔE HOMO is preferably 0.4 eV or less, more preferably 0.3 eV or less. It is clear that the above is important.

[0250] In addition, the HOMO level of BPAFLP used in the hole transport layer is -5.51 eV. Therefore, the HOMO level of the third organic compound used in the hole transport layer is The HOMO level is lower than that of the organic compound PCBBiF, and the HOMO level of the second organic compound The HOMO levels of PCBBiF and the first organic compound (2mPCCzPDBq-02 or 2mPCCzPDBq) HOMO level. This is important in terms of injecting holes not only into the second organic compound but also into the first organic compound in part. . EXAMPLES

[0251] In this example, a development process was carried out using a dibenzo[f,h]quinoxaline derivative which is one embodiment of the present invention. An optical element 4 was fabricated. The structure of the light-emitting element was the same as that of Example 5, using FIG. 22. The chemical formulas of the materials used in this embodiment are shown below.

[0252] [ka]

[0253] <Fabrication of light-emitting element 4> First, indium tin oxide containing silicon oxide (ITSO) is deposited on a glass substrate 1100. A film was formed by a sputtering method to form a first electrode 1101 that functions as an anode. The film thickness was 110 nm and the electrode area was 2 mm × 2 mm.

[0254] Next, as a pretreatment for forming the light emitting element 4 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.

[0255] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. After vacuum baking at 170° C. for 30 minutes in the heating chamber of the device, the substrate 1100 is It was left to cool for about 0 minutes.

[0256] Next, the substrate 1100 is vacuum-deposited so that the surface on which the first electrode 1101 is formed faces downward. The EL layer 11 was fixed to a holder provided in the device. 02, a hole injection layer 1111, a hole transport layer 1112, a light emitting layer 1113, and an electron transport layer A case where a layer 1114 and an electron injection layer 1115 are formed in this order will be described.

[0257] The vacuum deposition equipment was -4 After reducing the pressure to 100 Pa, 1,3,5-tri(dibenzothiophene 4-yl)benzene (abbreviation: DBT3P-II) and molybdenum oxide, The first electrode was formed by co-evaporating I and molybdenum oxide in a ratio of 4:2 (mass ratio). A hole injection layer 1111 was formed on the substrate 1101. The thickness of the layer was set to 20 nm. It is a deposition method in which different substances are evaporated simultaneously from different evaporation sources.

[0258] Next, 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) was evaporated to a thickness of 20 nm to form a hole transport layer 1112. .

[0259] Next, the light-emitting layer 1113 was formed on the hole-transporting layer 1112. 9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}di Benzo[f,h]quinoxaline (abbreviation: 2PCCzPDBq-02 (structural formula (102)) ), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazolyl) 9,9-dimethyl-9H-fluoren-2-amine( Abbreviation: PCBBiF), (acetylacetonato)bis(4,6-diphenylpyrimidinate ) Iridium(III) (abbreviation: [Ir(dppm)2(acac)]) in 2PCCz PDBq-02:PCBBiF:[Ir(dppm)2(acac)]=0.7:0.3 :0.05 (mass ratio) and formed into a film with a thickness of 20 nm, and then 2PCCzP DBq-02:PCBBiF:[Ir(dppm)2(acac)]=0.8:0.2: The layer structure was formed by co-evaporating the material so that the mass ratio was 0.05 and the thickness was 20 nm. The light-emitting layer 1113 having the above structure was formed to a thickness of 40 nm.

[0260] Next, 2PCCzPDBq-02 was deposited at 20 nm on the light-emitting layer 1113, and then An electron transport layer 1114 is formed by depositing 10 nm of benzophenone (abbreviation: Bphen). Formed.

[0261] Furthermore, lithium fluoride is deposited at 1 nm on the electron transport layer 1114 to inject electrons. A layer 1115 was formed.

[0262] Finally, aluminum was evaporated onto the electron injection layer 1115 to a thickness of 200 nm. A second electrode 1103 serving as a cathode was formed, and a light-emitting element 4 was obtained. In all the depositions, a resistance heating method was used.

[0263] The element structure of the thus obtained Light-emitting Element 4 is shown in Table 4.

[0264] [Table 4]

[0265] The fabricated light-emitting element 4 was placed in a glove box with a nitrogen atmosphere to prevent it from being exposed to the air. The device was sealed at 80°C (specifically, the sealing material was applied around the device, UV treatment was performed, and the device was sealed at 80°C). (Then, heat treatment was performed for 1 hour.)

[0266] <Operation characteristics of light-emitting element 4> The operating characteristics of the fabricated light-emitting element 4 were measured. The measurements were performed at room temperature (25° C.) The results are shown in Figs. 29 to 32.

[0267] Also, 1000cd / m 2 The main initial characteristic values ​​of the light-emitting element 4 in the vicinity are shown in Table 5 below. .

[0268] [Table 5]

[0269] In addition, the light-emitting element 4 is supplied with 2.5 mA / cm 2 The emission spectrum when a current is applied at a current density of As shown in FIG. 33, the light-emitting element 4 contains [Ir(dppm)2(acac)] The spectrum showed a peak at around 581 nm, which was due to

[0270] The results of a reliability test on the light-emitting element 4 are shown in FIG. The vertical axis shows the normalized luminance (%) when the initial luminance is 100%, and the horizontal axis shows the driving time of the element. The time (h) is shown. The reliability test was performed with an initial brightness of 5000cd / m 2 Set the current The light-emitting element 4 was driven under a constant density condition.

[0271] As a result, the light-emitting element 4 using 2PCCzPDBq-02, which is one embodiment of the present invention, has high It was found to be a reliable light-emitting element with a long life.

[0272] The results of measuring the amount of voltage change during a reliability test are shown in FIG. 34(B). The vertical axis is the voltage change The horizontal axis indicates the amount of light emitted (V), and the horizontal axis indicates the operation time of the element (h). It can be seen that the voltage rise of element 4 is small when driven at a constant current. For example, after about 500 hours of driving The amount of voltage rise after that is about 0.01 V for the light-emitting element 4. A comparative light-emitting element 9 was created using 2mDBTBPDBq-II instead of CzPDBq-02. When the device was fabricated and driven in the same manner, the voltage increase after about 500 hours of driving was about 0.06 V. In other words, the amount of voltage rise in the light-emitting element 4 is suppressed to about one-sixth of that in the comparative light-emitting element 9. It is clear that this is a significant effect.

[0273] In addition, 2PCCzPDBq-02 forms an exciplex with PCBBiF (this dibenzo The mixed film of quinoxaline compound and PCBBiF is similar to the single film of dibenzoquinoxaline compound. (Because it emits green light with a longer wavelength than the PCBBiF single film.) Since the HOMO level of q-02 is −5.68 eV, Δ E HOMO is 0.32 eV. From this result, ΔE HOMO is 0.4 eV or less It turns out that this is important.

[0274] In addition, the HOMO level of BPAFLP used in the hole transport layer is -5.51 eV. Therefore, the HOMO level of the third organic compound used in the hole transport layer is The HOMO level is lower than that of the organic compound PCBBiF, and the HOMO level of the second organic compound HOMO levels of PCBBiF and the HOM of the first organic compound (2PCCzPDBq-02) This means that the hole is transported not only to the second organic compound but also to the , it is important from the viewpoint of injecting a part of it into the first organic compound as well. EXAMPLES

[0275] <Synthesis Example 5> In this example, the synthesis method according to one embodiment of the present invention is (9H-carbazol-3-yl)-9H-carbazol-9-yl]biphenyl-3 -yl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzBPDBq) (structural formula (1 The synthesis method of 22) is explained below. The structure of 2mPCCzBPDBq is shown below. vinegar.

[0276] [ka]

[0277] <2-{3'-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-3-yl] 2m-phenyl-9-yl]biphenyl-3-yl}dibenzo[f,h]quinoxaline (abbreviation Synthesis of PCCzBPDBq) First, 2-(3'-bromobiphenyl-3-yl)dibenzo[f,h]quinoxaline 2. 0g (4.3mmol), 3-(9-phenyl-9H-carbazol-3-yl)-9H -Carbazole 1.8g (4.3mmol), sodium tert-butoxide 0.8 3g (8.6mmol) was added to a 100mL three-neck flask, mixed, and the flask was purged with nitrogen. 22 mL of mesitylene was added to this mixture, and the inside of the flask was reduced pressure and stirred. The mixture was degassed with and.

[0278] Next, bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd( dba)2) 25 mg (0.040 mmol) and 2-dicyclohexylphosphino-2' ,6'-dimethoxybiphenyl (S-Phos) 35 mg (0.09 mmol) was added The mixture was stirred at 150°C for 23 hours under a nitrogen stream. Water and toluene were added, and the aqueous layer of the filtrate was extracted with toluene. The extract and the organic layer were combined. The mixture was washed with an aqueous solution of sodium hydrogen carbonate and saturated saline, and then dried over magnesium sulfate. The mixture was gravity filtered, and the filtrate was concentrated to give an oily product. The oily product was dissolved in toluene and The solution was filtered through a stack of Celite and alumina with suction. The filtrate was concentrated. A brown oil was obtained. This oil was purified by high performance liquid chromatography. Chromatography was performed using chloroform as the developing solvent (column Pressure 4.5 MPa, flow rate 100 mL / min, holding time 45 minutes, injection volume 0.9 g / 30 mL). The obtained fraction was concentrated and recrystallized with hexane, yielding the desired yellow powder in 0. Obtained 66 g, 18% yield.

[0279] The yellow powdery solid (0.66 g) obtained was purified by sublimation using the train sublimation method. The sublimation purification conditions were a pressure of 2.6 Pa and an argon gas flow rate of 5 mL / min. After purification by sublimation, the yellow glassy phase of 2mPCCzBPDBq was obtained. 0.5 g of solid was obtained with a recovery rate of 83%. The synthesis scheme for this step is shown in (e-1) below. vinegar.

[0280] [ka]

[0281] Nuclear magnetic resonance spectroscopy of the yellow powdery solid obtained in the above step ( 1 Analysis by H-NMR The results are shown below. 1 The H-NMR charts are shown in Figures 35(A) and 35(B). 35(B) is a graph showing the horizontal axis (δ) of Fig. 35(A) from 7.0(ppm) to 10(ppm). From this, in the above step, 2-{3'-[3- (N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]bi Phenyl-3-yl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzBPDBq) (Structural formula (122)) was obtained.

[0282] 1 H NMR(CDCl3,500MHz):δ(ppm)=7.30-7.37(m, 2H), 7.41-7.53(m, 5H), 7.59-7.89(m, 18H), 8.0 4(dd, J=1.7Hz, 1H), 8.23(d, J=7.5Hz, 1H), 8.28 (d, 8.0Hz, 1H), 8.35(d, J=8.0Hz, 1H), 8.48(dd, J=11.4Hz, J=1.7Hz, 2H), 8.66(d, J=8.1Hz, 1H), 8.70(s, 1H), 9.25(dd, J=6.3Hz, J=1.1Hz, 1H), 9 .43(dd, J=7.5Hz, J=1.7Hz, 1H), 9.47(s, 1H). EXAMPLES

[0283] In this example, the dibenzo[f,h]quinoxaline derivative 2mPCC, which is one embodiment of the present invention, Light-emitting device 5 using zPDBq (structural formula (101)) and comparative material 2-[3-(9H-cal 2mDBTP Comparison of light-emitting element 6 using comparative material 2mCzPDBq The light-emitting element 7 was fabricated. The fabrication of each light-emitting element was basically the same as in Example 5. The chemical formulas of the materials used in this example are shown below.

[0284] [ka]

[0285] <Preparation of Light-Emitting Element 5, Comparative Light-Emitting Element 6, and Comparative Light-Emitting Element 7> The device structures of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7 prepared in this example are shown in FIG. Shown in 6.

[0286] [Table 6]

[0287] The fabricated light-emitting element 5, comparative light-emitting element 6, and comparative light-emitting element 7 were not exposed to the air. The device was sealed in a glove box with a nitrogen atmosphere to prevent damage to the device. (Then, the film is sealed with UV treatment and heat treated at 80℃ for 1 hour.)

[0288] <Operation characteristics of light-emitting element 5, comparative light-emitting element 6, and comparative light-emitting element 7> The operating characteristics of the fabricated light-emitting element 5, comparative light-emitting element 6, and comparative light-emitting element 7 were measured. The measurements were carried out at room temperature (atmosphere maintained at 25°C).

[0289] The current density-luminance characteristics of each light-emitting element are shown in FIG. 36, the voltage-luminance characteristics are shown in FIG. 37, and the luminance-current efficiency characteristics are shown in FIG. The characteristics are shown in Figure 38 and the voltage-current characteristics are shown in Figure 39.

[0290] Also, 1000cd / m 2 Light-emitting element 5, comparative light-emitting element 6, and comparative light-emitting element The main initial characteristic values ​​of Child 7 are shown in Table 7 below.

[0291] [Table 7]

[0292] Furthermore, the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7 were each subjected to a current of 2.5 mA / cm 2 Current FIG. 40 shows the emission spectrum when a current was applied at a density of 1000 nm. As shown in FIG. 40, the emission spectrum of the light-emitting element 5 , Comparative Light-Emitting Element 6, and Comparative Light-Emitting Element 7 are all [Ir(tBuppm)2(ac The spectrum showed a peak at around 544 nm, which was derived from the chromatographic method (a).

[0293] The results of the reliability test for the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7 are shown below. In FIG. 41(A), the vertical axis indicates the standard deviation when the initial luminance is 100%. The horizontal axis indicates the rated luminance (%), and the horizontal axis indicates the operation time (h) of the element. Brightness: 5000cd / m 2The light-emitting element 5 and the comparative light-emitting element 6 were measured under a constant current density. and comparative light-emitting element 7 were driven.

[0294] As a result, the light-emitting device 5 using 2mPCCzPDBq according to one embodiment of the present invention exhibited a Comparison light-emitting element 6 using TPDBq-II and comparison light-emitting element 7 using 2mCzPDBq It was found that this was a light emitting element with higher reliability and longer life than that of Device 7.

[0295] The results of measuring the amount of voltage change during a reliability test are shown in FIG. 41(B). The vertical axis is the voltage change The horizontal axis indicates the amount of light emitted (V), and the horizontal axis indicates the operation time of the element (h). The voltage rise of the element 5 when driven at a constant current is smaller than that of the comparative light-emitting elements 6 and 7. For example, looking at the voltage rise after about 1000 hours of operation, the comparative light-emitting element 6 The light-emitting element 5 had a voltage of about 0.01V, the light-emitting element 6 had a voltage of about 0.02V, and the light-emitting element 7 had a voltage of about 0.50V. 4 V. In other words, the voltage increase amount of the light-emitting element 5 is larger than that of the comparative light-emitting element 6 and the comparative light-emitting element 7. is significantly suppressed, which is a remarkable effect.

[0296] In addition, 2mPCCzPDBq, 2mDBTPDBq-II, and 2mCzPDBq are all , and form exciplexes with PCBBiF (these dibenzoquinoxaline compounds and PCBB The mixed films with iF were all more effective than the single films of each dibenzoquinoxaline compound and the single film of PCBBiF. (Because it emits yellow-green light with a longer wavelength than 2mPCCzPDBq, 2mDBTPD The HOMO levels of Bq-II, 2mCzPDBq, and PCBBiF are −5, respectively. 63 eV, -6.22 eV, -5.91 eV, and -5.36 eV. The potential was calculated from cyclic voltammetry (CV) measurements.

[0297] From the HOMO level measurement results, ΔE HOMO The results were as follows: The results are summarized in Table 8.

[0298] [Table 8]

[0299] From this result, ΔE HOMO It is preferable that the value is 0.4 eV or less, and more preferably 0.3 eV or less. It is clear that the above is important.

[0300] In addition, the HOMO level of BPAFLP used in the hole transport layer is -5.51 eV. Therefore, the HOMO level of the third organic compound used in the hole transport layer is The HOMO level is lower than that of the organic compound PCBBiF, and the HOMO level of the second organic compound The HOMO levels of PCBBiF and the first organic compound (2mPCCzPDBq) This means that the holes are not only transported through the second organic compound but also through the first organic compound. This is important from the perspective of injecting the organic compound in part 1. EXAMPLES

[0301] In this example, the dibenzo[f,h]quinoxaline derivative 2mPCC, which is one embodiment of the present invention, The light-emitting device 8 was fabricated using zBPDBq. The details are omitted since they are the same as those in Example 5. The chemical formulas of the materials used in this example are as follows: show.

[0302] [ka]

[0303] <Fabrication of light-emitting element 8> Table 9 shows the element structure of the light-emitting element 8 produced in this example.

[0304] [Table 9]

[0305] The fabricated light-emitting element 8 was placed in a glove box with a nitrogen atmosphere to prevent it from being exposed to the air. (Sealing material was applied around the element, and UV treatment was performed during sealing, and the device was sealed at 80°C.) Heat treatment for 1 hour).

[0306] <Operation characteristics of light-emitting element 8> The operating characteristics of the fabricated light-emitting device 8 were measured. The measurements were performed at room temperature (25° C.). I went there for the atmosphere.

[0307] FIG. 42 shows the current density-luminance characteristics of the light-emitting element 8, FIG. 43 shows the voltage-luminance characteristics, and FIG. 44 shows the luminance-current efficiency characteristics. The characteristics are shown in Figure 44 and the voltage-current characteristics are shown in Figure 45.

[0308] Also, 1000cd / m 2 The main initial characteristic values ​​of the light-emitting element 8 in the vicinity are shown in Table 10 below. vinegar.

[0309] [Table 10]

[0310] In addition, the light emitting element 8 is rated at 2.5 mA / cm 2 The emission spectrum when a current is applied at a current density of As shown in FIG. 46, the light-emitting element 8 contains [Ir(dppm)2(acac)] The spectrum showed a peak at around 584 nm, which was due to EXAMPLES

[0311] In this example, a light-emitting element which is one embodiment of the present invention was manufactured and subjected to a storage test.

[0312] In this embodiment, the light-emitting element 1A, the light-emitting element 2A, the comparative light-emitting element 3A, the light-emitting element 4A, The light-emitting element 8A was fabricated. The light-emitting element 1A had the same configuration as the light-emitting element 1 of Example 5 and was fabricated in the same manner. The light-emitting element 2A was fabricated according to the same method as the light-emitting element 2 of Example 5 and the comparative light-emitting element 3. A is the comparative light-emitting element 3 and the light-emitting element 4 of Example 5. A is the light-emitting element 4 and the light-emitting element 8 of Example 6. A had the same configuration as the light-emitting element 8 of Example 9 and was fabricated by the same fabrication method.

[0313] In the storage test in this embodiment, each light-emitting element was stored in a thermostatic chamber maintained at 100° C. After a certain time had passed, the operating characteristics were measured. The experiment was carried out at room temperature (atmosphere maintained at 25°C).

[0314] First, the voltage-current characteristics of the light-emitting element 1A when stored at 100° C. for a certain period of time are shown in FIG. The luminance-external quantum efficiency characteristics are shown in FIG. 48. In FIG. 47, the horizontal axis represents voltage (V) and the vertical axis represents represents the current (mA). In Figure 48, the horizontal axis represents the luminance (cd / m 2 ) and the vertical axis is the external quantity Represents the child efficiency (%).

[0315] Next, the voltage-current characteristics of the light-emitting element 2A when stored at 100° C. for a predetermined time are shown in FIG. The luminance-external quantum efficiency characteristics are shown in FIG. 50. In FIG. 49, the horizontal axis is voltage (V) and the vertical axis is represents the current (mA). In Figure 50, the horizontal axis represents the luminance (cd / m 2 ) and the vertical axis is the external quantity Represents the child efficiency (%).

[0316] Next, the voltage-current characteristics of the comparative light-emitting element 3A when stored at 100°C for a certain period of time are shown in FIG. The luminance vs. external quantum efficiency characteristics are shown in FIG. 52. In FIG. 51, the horizontal axis represents voltage (V), The vertical axis represents the current (mA). In Figure 52, the horizontal axis represents the luminance (cd / m 2 ) and the vertical axis is the outer The partial quantum efficiency (%) is shown in FIG. 52. Note that no luminescence was observed after storage for more than 20 hours. Therefore, data could not be obtained for storage longer than 20 hours.

[0317] Next, the voltage-current characteristics of the light-emitting element 4A when stored at 100° C. for a predetermined time are shown in FIG. The luminance-external quantum efficiency characteristics are shown in FIG. 54. In FIG. 53, the horizontal axis is voltage (V) and the vertical axis is represents the current (mA). In Figure 54, the horizontal axis represents the luminance (cd / m 2 ) and the vertical axis is the external quantity Represents the child efficiency (%).

[0318] Next, the voltage-current characteristics of the light-emitting element 8A when stored at 100° C. for a predetermined time are shown in FIG. The luminance-external quantum efficiency characteristics are shown in FIG. 56. In FIG. 55, the horizontal axis is voltage (V) and the vertical axis is represents the current (mA). In Figure 56, the horizontal axis represents the luminance (cd / m 2 ) and the vertical axis is the external quantity Represents the child efficiency (%).

[0319] 47 to 50 and 53 to 56, the light-emitting element 1A, the light-emitting element 2A, the light-emitting element 4A, and The light-emitting device 8A and the light-emitting device 9A were stored at 100° C. for 500 hours, but the voltage-current characteristics and There is little change in the luminance-external quantum efficiency characteristics, and there is little deterioration of the device characteristics due to storage at high temperatures. On the other hand, as can be seen from FIG. 51 and FIG. 52, the comparative light-emitting element 3A was stored at 100° C. The voltage-current characteristics and luminance-external quantum efficiency characteristics change significantly due to the temperature change. As shown in FIG. 51, the comparative light-emitting element 3A lost its initial characteristics after 100 hours. The insulation property of the semiconductor device cannot be maintained, and a leakage current occurs. Therefore, it is understood that the use of the compound of the present invention improves the high temperature retention of the light-emitting element. It can be seen that the heat resistance in storage is dramatically improved. [Explanation of symbols]

[0320] 100 Light-emitting layer 101 First organic compound (h) 102 Second organic compound (a) 103 Phosphorescent compounds (g) 104 Hole transport layer 105 Hole transporting compounds (p) 201 First electrode 202 EL layer 203 Second electrode 211 Hole injection layer 212 Hole transport layer 213 Light-emitting layer 214 Electron transport layer 215 Electron injection layer 401 First electrode 402(1) First EL layer 402(2) Second EL layer 402(n-1) EL layer (n-1) 402(n) EL layer (n) 404 Second electrode 405 Charge generation layer 405(1) First charge generating layer 405(2) Second charge generating layer 405(n-1) (n-1)th charge generating layer 501 Substrate 502 FET 503 First electrode 504 Bulkhead 505 EL layer 506R, 506G, 506B, 506Y Light Emitting Area 507R, 507G, 507B, 507Y Light emitting element 508R, 508G, 508B, 508Y colored layer 509 Black layer (black matrix) 510 Second electrode 511 Sealing substrate 601 Element substrate 602 Pixel section 603 Driver circuit section (source line driver circuit) 604a, 604b Drive circuit section (gate line drive circuit) 605 Sealing material 606 Sealing substrate 607 Wiring 608 FPC (Flexible Printed Circuit) 609 FET 610 FET 611 Switching FET 612 Current Control FET 613 First electrode (anode) 614 Insulation 615 EL layer 616 Second electrode (cathode) 617 Light emitting element 618 Space 1100 Substrate 1101 First electrode 1102 EL layer 1103 Second electrode 1111 Hole injection layer 1112 Hole transport layer 1113 Light-emitting layer 1114 Electron transport layer 1115 Electron injection layer 7100 Television equipment 7101 Case 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 7302 Case 7304 Display Panel 7305 Time Icon 7306 Other Icons 7311 Operation button 7312 Operation button 7313 Connection terminal 7321 Band 7322 Clasp 7400 Mobile Phone 7401 Case 7402 Display section 7403 Operation button 7404 External connection part 7405 Speaker 7406 Mike 7407 Camera 8001 Lighting equipment 8002 Lighting equipment 8003 Lighting equipment 8004 Lighting equipment 9310 Mobile Information Terminal 9311 Display Panel 9313 Hinge 9315 Case

Claims

1. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.4 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

2. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.4 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

3. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.33 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

4. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.33 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

5. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.32 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

6. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.32 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

7. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.3 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

8. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.3 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

9. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.27 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

10. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.27 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

11. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.33 eV or less.

12. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.33 eV or less.

13. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.32 eV or less.

14. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.32 eV or less.

15. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.27 eV or less.

16. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; the 6-membered nitrogen-containing heteroaromatic ring is any one of pyrazine, pyridazine, triazine, and tetrazine; a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.27 eV or less.

17. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.4 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

18. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.4 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

19. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.33 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

20. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.33 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

21. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.32 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

22. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.32 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

23. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.3 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

24. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.3 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

25. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.27 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

26. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.27 eV or less; A light-emitting element, wherein the HOMO level of the first organic compound and the HOMO level of the second organic compound are values ​​calculated by cyclic voltammetry measurement.

27. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.33 eV or less.

28. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.33 eV or less.

29. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.32 eV or less.

30. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.32 eV or less.

31. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; an emission spectrum of a mixed film of the first organic compound and the second organic compound is located on a longer wavelength side than a fluorescence spectrum of a film of the first organic compound and a fluorescence spectrum of a film of the second organic compound; the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.27 eV or less.

32. A light-emitting layer is disposed between an anode and a cathode, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent compound; the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound contains a nitrogen-containing heteroaromatic ring composed of a 6-membered ring and a carbazole skeleton, but does not contain a triarylamine skeleton; a benzene ring is condensed to the 6-membered nitrogen-containing heteroaromatic ring, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; A light-emitting element, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.27 eV or less.

33. In any one of claims 17 to 32, The six-membered nitrogen-containing heteroaromatic ring is any one of pyridine, pyrazine, pyrimidine, pyridazine, triazine, and tetrazine.

34. In any one of claims 17 to 32, The nitrogen-containing heteroaromatic ring composed of a 6-membered ring to which a benzene ring is condensed is any one of quinoline, isoquinoline, dibenzo[f,h]quinoline, naphthyridine, dibenzo[f,h]quinoxaline, and dibenzo[f,h]quinazoline.

35. In any one of claims 1 to 34, A light-emitting device comprising a hole-transporting layer located between the anode and the light-emitting layer.

36. A light-emitting element according to any one of claims 1 to 35 and a transistor, the transistor is electrically connected to the light-emitting element.

37. A light emitting element according to any one of claims 1 to 35 or a light emitting device according to claim 36; An electronic device having at least one of a connection terminal and an operation key.

38. A lighting device comprising the light-emitting device according to claim 36 and a housing.

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