Light-emitting element

Abstract

To provide a light-emitting element with improved reliability, a light-emitting element with high current efficiency (or quantum efficiency), and a novel dibenzo[f,h]quinoxaline derivative that is preferably used for a light-emitting element according to one aspect of the present invention.SOLUTION: An EL layer is provided between an anode and a cathode. The EL layer includes a light-emitting layer. The light-emitting layer contains a first organic compound with electron transporting property and hole transporting property, a second organic compound with hole transporting property, and a light-emitting material. The first organic compound and the second organic compound are the combination that forms an excitation complex. The HOMO level of the first organic compound is lower than the HOMO level of the second organic compound. The difference between the HOMO level of the first organic compound and the HOMO level of the second organic compound is 0.4 eV or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, relating to the manufacture or composition of matter, especially 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. Furthermore, the present invention 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] It uses organic compounds as light emitters, which have characteristics such as thinness, light weight, high-speed response, and low DC voltage drive. The light-emitting element is expected to be applied to next-generation 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 angle and excellent visibility.

[0003] The light-emitting mechanism 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 light-emitting 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 the excited state is singlet excited and triplet excited, and the emission is It is believed that either excited state is possible.

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

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-182699 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 device, the capacitance of the EL layer of the light-emitting device is It is necessary to have an element configuration that allows for rear balance control and improves the carrier recombination probability. Therefore, by making the EL layer into a desired device configuration, carrier movement in the light-emitting layer can be improved. Furthermore, 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 improve reliability. .

[0007] In view of this, one embodiment of the present invention provides a light-emitting element with improved reliability. Furthermore, 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. 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 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 present invention to solve all of these problems. The above will be made clear from the description, 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 comprises a first organic compound having electron transport properties and hole transport properties, and a second organic compound having hole transport properties. The organic compound includes a second organic compound and a light-emitting material, and the first organic compound and the second organic compound are an excitation light source. 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 another embodiment of the present invention, an EL layer is provided 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. a second organic compound having a property of being luminescent, and a light-emitting material, The compound is a combination that forms an exciplex, and the first organic compound is a six-membered nitrogen-containing compound. 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 another embodiment of the present invention, an EL layer is provided 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. a second organic compound having a property of being luminescent, and a light-emitting material, 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 characterized by including a triarylamine skeleton. do.

[0011] In the above structure, the bicarbazole skeleton is a 3,3'-bicarbazole skeleton, or is characterized by 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 hole transport properties. a light-emitting element having a HOMO level lower than that of the second organic compound; 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 following characteristics.

[0015] [ka]

[0016] 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 groups having 5 to 7 carbon atoms, substituted or unsubstituted aryl groups having 6 to 13 carbon atoms group, 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, 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 groups having 5 to 7 carbon atoms, substituted or unsubstituted aryl groups having 6 to 13 carbon atoms group, 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] However, in the formula, R 1 ~R 24 are each independently hydrogen, a substituted or unsubstituted group having 1 to 10 carbon atoms, 6 alkyl group, substituted or unsubstituted cycloalkyl group having 5 to 7 carbon atoms, substituted or unsubstituted or an unsubstituted aryl group having 6 to 13 carbon atoms, and Ar is a substituted or unsubstituted The arylene group represented by Ar is an arylene group having 6 to 25 carbon atoms, or a single bond. Therefore, it is preferred that the anthracenylene group is not contained.

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

[0024] [ka]

[0025] However, in the formula, R 1 ~R 24 are each independently hydrogen, a substituted or unsubstituted group having 1 to 10 carbon atoms, 6 alkyl group, substituted or unsubstituted cycloalkyl group having 5 to 7 carbon atoms, substituted or unsubstituted or an unsubstituted aryl group having 6 to 13 carbon atoms, and Ar is a substituted or unsubstituted The arylene group represented by Ar is an arylene group having 6 to 25 carbon atoms, or a single bond. Therefore, it is preferred that the anthracenylene group is not contained.

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

[0027] [ka]

[0028] However, in the formula, R 1 ~R 24 are each independently hydrogen, a substituted or unsubstituted group having 1 to 10 carbon atoms, 6 alkyl group, substituted or unsubstituted cycloalkyl group having 5 to 7 carbon atoms, substituted or unsubstituted or an unsubstituted aryl group having 6 to 13 carbon atoms, and Ar is a substituted or unsubstituted The arylene group represented by Ar is an arylene group having 6 to 25 carbon atoms, or a single bond. Therefore, it is preferred that the anthracenylene group is not contained.

[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 a pentyl group and a hexyl group. Examples of the cyclopentyl 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-diol. ,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''-terbenzen-3, 3''-diyl group, 1,1':4',1''-tert-benzene-3,3''-diyl group, 1 ,1':4',1''-tert-benzene-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 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-fluorenylene group Nylene group, 9,9-dimethyl-1,4-fluorenylene group, spiro-9,9'-bifluorenylene group 2,7-phenanthrenylene group, 9,10-dihydro-2,7-phenanthrenylene group, -phenanthrenylene group, 3,6-phenanthrenylene group, 9,10-phenanthrenylene group phenylene group, 2,7-triphenylenylene group, 3,6-triphenylenylene group, 2,8-benzo [a]phenanthrenylene group, 2,9-benzo[a]phenanthrenylene group, 5,8-benzo[a]phenanthrenylene group Examples include 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 carbon atoms are also usable. The aryl group having 1 to 13 carbon atoms and the arylene group having 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, and the like. butyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, hexyl group alkyl groups having 1 to 6 carbon atoms, such as cyclopentyl groups, cyclohexyl groups, and cycloheptyl groups Cycloalkyl groups with 5 to 7 carbon atoms, such as phenyl, tolyl, xylyl, and biphenyl. Phenyl group, indenyl group, naphthyl group, fluorenyl group, 9,9'-dimethylfluorene 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 a photosensitive layer comprising: 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 and a light-emitting device Electronic equipment to which the device is applied (specifically, the light emitting element or the light emitting device and the connection terminal or the operation 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 COG (Chip on Glass) All modules with ICs (integrated circuits) directly mounted using the p On Glass method are also This is included in the light-emitting device. [Effects of the Invention]

[0034] According to one aspect of the present invention, novel dibenzo[f,h]quinoxaline derivatives are provided. According to another aspect of the present invention, the dibenzo[f,h]quinoxaline derivative can be prepared by the method of E The present invention relates to a light-emitting element, a light-emitting device, an electronic device, and an optical element, which are used as an EL material and have high luminous efficiency and high reliability. In addition, one aspect of the present invention provides a novel material. Another embodiment of the present invention provides a novel light-emitting element and a light-emitting device. 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 explanation of the drawings]

[0035] [Figure 1] 1A and 1B are diagrams illustrating a light-emitting layer of a light-emitting element. [Figure 2] 1A and 1B are diagrams illustrating a light-emitting layer of a light-emitting element. [Figure 3] 1A to 1C illustrate a structure of a light-emitting element. [Figure 4] 1A to 1C illustrate a structure of a light-emitting element. [Figure 5] 1A and 1B illustrate a light-emitting device. [Figure 6] 1A and 1B illustrate a light-emitting device. [Figure 7] 1A and 1B are diagrams illustrating electronic devices. [Figure 8] 1A and 1B 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 and 1B illustrate structures of a light-emitting element 1, a light-emitting element 2, and a comparative light-emitting element 3. [Figure 23] 10 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] 10 shows voltage-luminance characteristics of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. [Figure 25] 10 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] 10 shows voltage-current characteristics of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. [Figure 27] 10 shows emission spectra of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. FIG. [Figure 28] 10 shows the reliability of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3. [Figure 29] FIG. 10 is a graph showing current density-luminance characteristics of Light-emitting element 4. [Figure 30]FIG. 10 shows voltage-luminance characteristics of the light-emitting element 4. [Figure 31] FIG. 10 shows luminance-current efficiency characteristics of Light-emitting Element 4. [Figure 32] FIG. 10 is a graph showing voltage-current characteristics of the light-emitting element 4. [Figure 33] FIG. 10 shows an emission spectrum of the light-emitting element 4. [Figure 34] FIG. 10 shows the reliability of the light-emitting element 4. [Figure 35] 1H-NMR chart of the dibenzo[f,h]quinoxaline derivative shown in structural formula (122). [Figure 36] 10 is a graph showing current density-luminance characteristics of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. FIG. [Figure 37] 10 is a graph showing voltage-luminance characteristics of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. [Figure 38] 10 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] 10 shows voltage-current characteristics of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. [Figure 40] 10 shows emission spectra of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. FIG. [Figure 41] 10 shows the reliability of the light-emitting element 5, the comparative light-emitting element 6, and the comparative light-emitting element 7. [Figure 42] 10 is a graph showing current density-luminance characteristics of the light-emitting element 8. FIG. [Figure 43] FIG. 10 is a graph showing voltage-luminance characteristics of the light-emitting element 8. [Figure 44] FIG. 10 shows luminance-current efficiency characteristics of the light-emitting element 8. [Figure 45] FIG. 10 is a graph showing voltage-current characteristics of the light-emitting element 8. [Figure 46] FIG. 10 is a graph showing an emission spectrum of the light-emitting element 8. [Figure 47] FIG. 10 is a graph showing voltage-current characteristics of the light-emitting element 1A in a storage test. [Figure 48] FIG. 10 is a graph showing luminance-external quantum efficiency characteristics of the light-emitting element 1A in a storage test. [Figure 49]FIG. 10 is a graph showing voltage-current characteristics of the light-emitting element 2A in a storage test. [Figure 50] FIG. 10 is a graph showing luminance-external quantum efficiency characteristics of the light-emitting element 2A in a storage test. [Figure 51] FIG. 10 is a graph showing voltage-current characteristics of the comparative light-emitting element 3A in a storage test. [Figure 52] FIG. 10 is a graph showing the luminance-external quantum efficiency characteristics of the comparative light-emitting element 3A in a storage test. [Figure 53] FIG. 10 is a graph showing voltage-current characteristics of the light-emitting element 4A in a storage test. [Figure 54] FIG. 10 is a graph showing luminance-external quantum efficiency characteristics of the light-emitting element 4A in a storage test. [Figure 55] FIG. 10 is a graph showing voltage-current characteristics of the light-emitting element 8A in a storage test. [Figure 56] FIG. 10 is a graph showing luminance-external quantum efficiency characteristics of the light-emitting element 8A in a storage test. DETAILED DESCRIPTION OF THE INVENTION

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the form and details thereof may be changed without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the embodiments described below. It is not to be construed as being limited to the

[0037] The words "film" and "layer" may be used interchangeably depending on the situation. For example, the term "conductive layer" can be replaced with "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) ) and an EL layer including a light-emitting layer is sandwiched between the electrons. It 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] At this time, the light-emitting layer 100 contains a first layer having electron transport properties and hole transport properties as shown in FIG. The organic compound (h) 101 has a hole transporting property, and the second organic compound (a) 102 has a hole transporting property. The first organic compound (h) 101 and the second organic compound (h) 102 are included. The organic compound (a) 102 is an exciplex (also called an exciplex). That is, at least the first organic compound (h) 10 The lowest unoccupied molecular orbital (LUMO) of 1 The LUMO level of the second organic compound (a) is lower than the LUMO level of the second organic compound (a). , 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 )102 is lower than the HOMO level. 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 (HOMO(a)) of the organic compound (a)102 (i.e., 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) 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 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, and ΔE e The light-emitting layer 10 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 starting voltage) similar to that of the light emitting layer 100. However, in one organic compound, the triplet excitation energy is higher than the singlet excitation energy. Therefore, the triplet excitation energy is transferred to the luminescent material (guest material). It is difficult to transfer energy to the exciplex and have it contribute to luminescence. It has the characteristic that the singlet excitation energy and triplet excitation energy are located at almost the same position. Therefore, both singlet and triplet excitation energy are transferred to the luminescent material. As a result, in addition to the effect of lowering voltage, the effect of increasing efficiency can be obtained. The details of the mechanism of this high efficiency are described below.

[0044] When the luminescent material is a phosphorescent compound, the singlet excitation energy and triplet excitation energy of the exciplex are Both of the energy transfers to the triplet excited state of the phosphorescent compound, and the triplet excited state This is most preferable from the viewpoint of high efficiency, since the light emitted from the luminescent material is converted into light emitted from the luminescent material (i.e., phosphorescence).

[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 substance, 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. The energy is transferred to the triplet excited state of the nucleus, but the triplet excited state is partially or completely activated by thermal activation. All or part of the luminescent material undergoes reverse intersystem crossing to the singlet excited state, which is ultimately converted into fluorescent light. 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 the 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 into the triplet excitation energy of the luminescent material. At first glance, it seems that high efficiency cannot be achieved because energy is transferred to the activated state and thermal deactivation occurs. However, the energy donor exciplex generates singlet excitation energy and triplet excitation energy. Because the difference in photoexcitation 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, either 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 when 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, a light-emitting device using an exciplex as an energy donor in the light-emitting layer can emit light with a phosphorescent compound. The compound used as the luminescent material is a compound having a thermally activated delayed fluorescent property, a compound having a fluorescent property, or a compound having a thermally activated delayed fluorescent property. Although this method is useful in such cases, it can cause problems in terms of controlling the light-emitting region.

[0048] As mentioned above, at least the LUMO level (LU MO(h)) is higher than the LUMO level (LUMO(a)) of the second organic compound (a). The energy level is low, and the HOMO level (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 2 is the condition for forming an exciplex. 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, N-(1, 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 MO(a)) is -5.36 eV, so ΔE HOMO is as much as 0.86 eV.

[0049] In this way, 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 The difference (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. That is, 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 is an excess of holes, that is, holes 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 disrupted due to long-term operation. If the recombination efficiency is reduced, the brightness will be deteriorated. HOM OWhen the value of θ is large, holes are accumulated in the second organic compound (a) 102, and the electrons in the light-emitting layer 100 On the other hand, the recombination region in the light-emitting layer 100 tends to be wider. However, since the entire light-emitting layer 100 can be used, it can be said that the reliability is higher.

[0050] Furthermore, the electron injection capability of light-emitting elements decreases with the deterioration of the electron injection electrode (cathode), etc. The recombination region often shifts toward the cathode due to long-term operation. Therefore, if the light-emitting layer 100 has poor hole transport properties, the average distance for the holes to be transported to the light-emitting layer 100 will be 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 levels (HOMO(a)) of organic compounds (a) (ΔE HOMO ) is large In the case of the light-emitting layer 100, since holes are difficult to move in the light-emitting layer 100, this problem tends to become more pronounced. do.

[0051] In a light-emitting device in which the above-described 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 layers, and the emitting layer 100 has electron transporting and A first organic compound (h) 101 having hole transport properties and a second organic compound (h) 102 having hole transport properties. 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 lower than 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 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, it is easier to maintain the carrier balance. 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) 10 Recombination can occur at 1, resulting in the formation of an excited state of the first organic compound, but this is rapid. Since the exciplex is quickly converted into 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 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] The compounds suitable for realizing the above concept are as follows: First, the first organic compound (h) 101 contains a six-membered nitrogen-containing heteroaromatic ring and a carbazole skeleton, and is a triaromatic ring. It is preferable that the compound does not contain an arylamine skeleton. The compound has an electron transport property and contains a carbazole skeleton and a triarylamine skeleton. It is preferable that the compound has a moderate hole transporting property by not containing the second active ingredient. The organic compound (a) 102 is a compound having hole transport properties, and the first organic compound (h) 1 It is preferable that the compound contains a triarylamine skeleton in order to increase the HOMO level higher than that of O1. .

[0055] Many compounds containing triarylamine skeletons can be measured by cyclic voltammetry (CV). 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 a 3,3'-bicarbazole skeleton or a 2,3'-bicarbazole skeleton is introduced, Since the HOMO level is in the vicinity of −5.6 to −5.7 eV, the first Suitable for organic compounds (h) 101.

[0056] In addition, examples of the six-membered nitrogen-containing heteroaromatic ring include 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. The six-membered nitrogen-containing heteroaromatic rings fused with rings include quinoline, isoquinoline, dibenzo[ f,h] quinoline. Also, quinoxaline, quinazoline, and phthalazine are representative. naphthyridine, dibenzo[f,h]quinoxaline, and dibenzo[f,h]quinazoline are also useful.

[0057] In one embodiment of the present invention, as described above, not only the second organic compound (a) 102 but also 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) In order to improve 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 hole transport properties. The HOMO level (HOMO(p)) of the organic compound (p)105 is higher than that of the second organic compound (a)10 It is preferable that the HOMO level of 2 is lower than the HOMO level (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 MO level (HOMO(h)) is between 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. This will be used 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 containing Indium oxide-tin oxide, Indium oxide-zinc oxide (Indium 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 to these, elements belonging to Groups 1 and 2 of the periodic table, such as lithium (Li) and cesium (Ce), Alkali metals such as cesium (Cs), calcium (Ca), strontium (Sr), etc. alkaline earth metals, magnesium (Mg), and alloys containing these (MgAg, Al rare earth metals such as Li, europium (Eu), ytterbium (Yb) and An alloy containing graphene or the like can be used. The second electrode (cathode) 203 is formed by, for example, sputtering or vapor 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, which has high hole transport properties. This is the injection layer, and it is made of a substance with high hole transporting properties (also called a hole transporting compound) and an acceptor. The layer contains a substance with high hole transporting properties and an acceptor substance. The scepter material pulls out electrons from the material with high hole transport properties, generating holes. Holes are injected into the light-emitting layer 213 through the hole transport layer 212. The layer 12 is formed using a material with high hole transporting properties.

[0061] The hole-injecting layer 211 and the hole-transporting layer 212 may be formed of a material having a high hole-transporting property, for example. 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-3-yl Rubazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenyl) PCzPCN 1) and the like. 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 with a hole mobility of 1 / Vs or more. However, other materials may be used as long as they have a higher hole transporting property than electron transporting property.

[0062] Furthermore, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenyl ether) 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 (abbreviated as Poly-TPD) 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, if the light-emitting layer 213 has the structure shown in FIG. In this case, the first organic compound having electron transport properties and hole transport properties described later and the The light-emitting element 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, the exciplex is formed, and the fluorescent spectrum of the first organic compound is The fluorescence spectra of the first and second organic compounds are similar to those of the exciplexes located at longer wavelengths. 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 spectra overlap. 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 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 able to trap (or transport) not only electrons but also holes. 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 (GO) It is suitable.

[0066] [ka]

[0067] (wherein 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. It is preferable that:

[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 (abbreviated as 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 (abbreviated as 2mPCCzPDBq-02).

[0070] Compounds that readily accept holes include, for example, 4-phenyl-4'-(9-phenyl-4 ... (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 (abbreviated as 1'-TNAT A), 2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]- Spiro-9,9'-bifluorene (abbreviation: DPA2SF), N,N'-bis(9-phenyl) (N,N'-diphenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviated :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- phenylamino]biphenyl (abbreviation: TPD), 4,4'-bis[N-(4-diphenylamino)biphenyl 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-phenylcarbazole) phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole ( Examples include compounds having a triarylamine skeleton 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 peak of the emission spectrum of the exciplex overlaps with the absorption spectrum of the luminescent material. It is sufficient if the wavelength is longer than the peak of the torque.

[0072] The first organic compound is a compound that readily accepts electrons and a compound that readily accepts holes. When the first organic compound and the second organic compound are mixed, the carrier balance can be controlled by the mixing 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 material that can be used as the light-emitting substance and the light-emitting center substance is is a luminescent material that converts singlet excitation energy into luminescence, or triplet excitation energy into luminescence. The luminescent materials that change the luminescent material into the luminescent material can be used alone or in combination. Examples of the substance and the luminescent center substance include the following:

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

[0075] Fluorescent substances include 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]phenyl ]-9H-carbazol-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 amine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9, 10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4- phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9, 10-diphenyl-2-anthryl)phenyl]-9H-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)-3-amine (abbreviation: 2PCABPhA), (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 [N-phenyl-9-ylphenyl]-N-phenylanthracen-2-amine (abbreviation: 2YG ABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAP hA), Coumarin 545T, N,N'-Diphenylquinacridone (abbreviation: DPQd), Prene, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetrahydrofuran Thracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethene {6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviated as DCM 1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzyl benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propan Dibenzonitrile (abbreviation: 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 (phosphors Fluorescent compounds and TADF materials that exhibit TADF Delayed fluorescence in TADF materials is similar to normal fluorescence. It is a type of light emission that has a spectrum and a very long lifespan. -6 More than a second, Preferably 10 -3 More than a second.

[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’ ) Iriji 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)), bicarbonate bis(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-phenylpyrazinato)iridium(III) (abbreviation :[Ir(mppr-Me)2(acac)]), (acetylacetonato)bis(5-acetylacetonato)bis(5-acetylacetonato) isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [I r(mppr-iPr)2(acac)]), (acetylacetonato)bis(2,3,5 -triphenylpyrazinate)iridium(III) (abbreviation: Ir(tppr)2(aca c)), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridine 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- Platinum porphyrin (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] TADF materials include, for example, fullerenes and their derivatives, and activators such as proflavine. Lysine derivatives, eosin, etc. Also, magnesium (Mg), zinc (Zn), Cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or para Examples of the metal-containing porphyrin include metal-containing porphyrins containing palladium (Pd). For example, protoporphyrin-tin fluoride complex (SnF2(Proto IX) ), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin Porphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetroxide tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octamethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), 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 π-electron rich heteroaromatic rings and π-electron deficient heteroaromatic rings such as ,5-triazine (PIC-TRZ) A heterocyclic compound having an aromatic ring can also be used. The materials in which the π-electron-deficient heteroaromatic ring is directly bonded to the π-electron-rich heteroaromatic ring exhibit the donor property and 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 because it reduces the size.

[0079] The light-emitting layer 213 may have a laminated structure as shown in FIG. In this case, each layer 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 phosphorescent light. In the layer from which phosphorescence is obtained, the exciplex is It is preferable that the structure be such that light emission is obtained by energy transfer from the organic compound to the dopant. Regarding the color of emitted light, if blue light is emitted from one layer, orange light is emitted from the other layer. It is possible to obtain a structure in which colored light or yellow light can be emitted. A configuration containing several types of dopants may also be used.

[0080] The electron transport layer 214 is a layer containing a substance with high electron transporting properties (also referred to as 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 Aluminum(III) (abbreviation: BAlq), bis[2-(2-hydroxyphenyl)benz[ 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-isopropyl-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 substance has a higher electron transporting property than a hole transporting property, Materials other than those mentioned above may be used for the electron transport layer 214 .

[0081] The electron transport layer 214 may be a single layer or may be 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 such as erbium fluoride (ErF3) can also be used. Alternatively, an electride may be used for the electron injection layer 215. The electride may be, for example, a mixed oxide of calcium and aluminum with electrons. The material constituting the electron transport layer 214 may be a material containing a high concentration of can also be used.

[0083] The electron injection layer 215 is made of a composite material obtained by mixing an organic compound and an electron donor (donor). Such composite materials are formed by electron donors generating electrons in organic compounds. 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 metals are preferably alkali metals, alkaline earth metals, or rare earth metals, and more preferably lithium, cesium, magnesium, 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, Examples of the base include barium oxide. 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 ink jet method, a coating method, and the like, respectively. It can be formed by a method such as a fabric 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 transmitted to either the first electrode 201 or the second electrode 203. 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 (a Energy transfer can be achieved by utilizing the overlap of the absorption spectrum with that of the quartz crystal (the material). Therefore, a light-emitting device with 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 shall be possible to do so.

[0088] (Embodiment 2) In this embodiment, a dibenzo[f, h]Quinoxaline derivatives will be explained.

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

[0090] [ka]

[0091] 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 groups having 5 to 7 carbon atoms, substituted or unsubstituted aryl groups having 6 to 13 carbon atoms group, 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.

[0092] The dibenzo[f,h]quinoxaline derivative represented by the above general formula (G0) is as follows: First, as shown in the following synthesis scheme (a), , a halogen compound of a dibenzo[f,h]quinoxaline derivative (A1) and bicarbazole By reacting the derivative with an arylboronic acid compound (A2), 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 groups having 5 to 7 carbon atoms, substituted or unsubstituted aryl groups having 6 to 13 carbon atoms group, 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 boronic acid ester or a cyclic tetracarboxylic acid. 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 a hydrogen atom. Represents.

[0095] In addition, as shown in the following synthesis scheme (b), dibenzo[f,h]quinoxaline derivatives 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 carrying out the reaction, the dibenzo[f,h]quinoxaline derivative (G0) can also 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 groups having 5 to 7 carbon atoms, substituted or unsubstituted aryl groups having 6 to 13 carbon atoms group, 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. X represents a halogen atom. B represents a boronic acid or a boronic acid ester. It represents a cyclic triol borate salt or a cyclic triol borate salt.

[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 and can be synthesized by the above-mentioned synthesis method, The [f,h]quinoxaline derivative is more preferably one represented by the above general formulas (G1) to (G3). In addition, the compounds represented by the general formulas (G0) to (G3) are embodiments of the present invention. The specific structural formula of the dibenzo[f,h]quinoxaline derivative is shown below (the following 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] Note that the dibenzo[f,h]quinoxaline derivative of one embodiment of the present invention can be By using it in a certain light emitting element, it is possible to obtain a light emitting element, a light emitting device, an electronic device, and the like having high light emitting efficiency and high reliability. Furthermore, a light-emitting element and a light-emitting device with low power consumption can be realized. , electronic devices, or lighting devices can be realized.

[0107] Furthermore, the dibenzo[f,h]quinoxaline derivatives represented by the general formulae (G0) to (G3) are Because of its electron-transporting and hole-transporting properties, it can be used as a host material in the light-emitting layer or as an electron-transporting It can be used as a transport layer or a hole transport layer. It can also be used as a light-emitting material in optical elements. The dibenzo[f,h]quinoxaline derivative represented by the following formula (I) is used as a material for a light-emitting element. Since they are novel compounds with a wide range of uses, dibenzofurans represented by general formulas (G0) to (G3) are 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 includes an EL layer sandwiched between a charge generation layer and an EL layer. A light emitting device having a structure having a plurality of light emitting elements (hereinafter referred to as a tandem light emitting device) will be described. As shown in FIG. 4(A), the tandem light emitting element has a pair of electrodes (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(1) and second EL layer 402(2). 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 can have the same structure as that in 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 the same structure, or either of them may have the same structure. The first EL layer 402(1) and the second EL layer 402(2) may have the same or different configurations. The same configuration as that of the first embodiment can be applied. , in one of the plurality of EL layers (first EL layer 402(1) and second EL layer 402(2)). The dibenzo[f,h]quinoxaline derivative shown in Embodiment Mode 2 can be used.

[0111] In addition, between the plurality of 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 this 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 4, the charge generation layer 405 generates a charge. Electrons are injected into the second EL layer 402(1) and holes are injected into the 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 charge generating layer 405 is 40% or more.) In addition, the charge generating layer 405 has a lower conductivity than the first electrode 401 and the second electrode 404. It still works.

[0113] The charge generation layer 405 is formed by adding an electron acceptor to an organic compound having high hole transport properties. Even if the structure is such that an electron donor (donor) is added to an organic compound with high electron transport properties, Alternatively, both of these structures may be stacked.

[0114] In the case where an electron acceptor is added to an organic compound having high hole transport properties, Examples of highly permeable organic compounds include NPB, TPD, TDATA, MTDATA, 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylalanine 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 an organic compound has a higher hole transporting property than an electron transporting property, a substance other than those mentioned above can be used. It's okay.

[0115] The electron acceptor is 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroethylene. Examples include fluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. Further, transition metal oxides can be mentioned. Examples of oxides of metals belonging to the group include vanadium oxide, niobium oxide, Tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, lenium oxide Molybdenum oxide is particularly stable in the atmosphere. It 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 with an electron mobility of 1 / Vs or higher. Note that, other organic compounds may be used as long as they have a higher electron transporting property than hole transporting property. No.

[0117] The electron donor may be an alkali metal, an alkaline earth metal, a rare earth metal, or The metals belonging to Groups 2 and 13 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] 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 (where n is 3 or more) EL layers (402(1) to 402(n)) are stacked. The same can be applied to the light emitting device according to the present embodiment. When there are multiple EL layers between a pair of electrodes, as in the case of a device, By arranging the charge generation layers (405(1) to 405(n-1)), the current density can be kept low. It is possible to emit light in a high brightness range while maintaining a low current density, which allows for long-life elements. It can also 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 luminescent color of each EL layer different, the desired luminescent color can be obtained as a whole. For example, in a light-emitting element having two EL layers, the first The emission color of the first EL layer and the emission color of the second EL layer are in a complementary color relationship. 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 result in an achromatic color. 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) is obtained from the EL layer of the second electrode is possible. In this case, both the blue and yellow (or orange) emissions are the same fluorescent or phosphorescent emission. It is not necessary that blue emission is fluorescent emission and yellow emission (or orange emission) is phosphorescent emission. Furthermore, the optical path length in the light-emitting element may be A laminated structure suitable for adjusting the 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] (Fourth embodiment) In this embodiment, a colored layer (color filter or the like) is combined with the light emitting element described in the first embodiment. In this embodiment, a light-emitting device in which a light-emitting element and a 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, the partition wall 505 is formed to fill the ends of the adjacent first electrodes 503. 04 is provided.

[0125] Note that 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 An electrode 510 is formed on the EL layer 505. The EL layer 505 has a plurality of light-emitting elements that emit a plurality of monochromatic lights. 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 emit red light. 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 region 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, and In the region indicated by Y, yellow light is emitted in the direction of the arrow through the colored layer 508Y.

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

[0128] In addition, in order to fill the edges 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 protective layer.

[0129] In the configuration described above, the structure in which light is extracted to the sealing substrate 511 side (top emission) The light emitting device is a type (bore 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 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 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 These include plates, laminated films, paper containing fibrous materials, and substrate films. Examples of the substrate include barium borosilicate glass, aluminoborosilicate glass, or silicon dioxide. Examples of flexible substrates, laminated films, and base films include glass. Examples of such materials include polyethylene terephthalate (PET), Polyethylene naphthalate (PEN), polyethersulfone (PES), polytetrafluoroethylene There are plastics such as fluoroethylene (PTFE), or acrylic. Synthetic resin, polypropylene, polyester, polyvinyl fluoride, vinyl chloride, etc. Films made of polyamide, polyimide, aramid, epoxy, etc. In particular, semiconductor substrates, single crystal substrates, or SO By manufacturing transistors using an I substrate, etc., characteristics, size, shape, etc. can be To manufacture transistors with small size, high current supply capacity, and low variation in By configuring a circuit using such transistors, it is possible to reduce the power consumption of the circuit, This allows for higher circuit integration.

[0131] In addition, a flexible substrate is used as the substrate, and a transistor or a light-emitting element is 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 substrates with poor heat resistance or flexible substrates. The above-mentioned peeling layer may be formed of, for example, a tungsten film and a silicon oxide film. The laminated structure of inorganic film and polyimide film, and the structure in which organic resin film such as polyimide is formed on the 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 different substrates. An example of a substrate on which a transistor or a light emitting element is transferred is a substrate on which the above-mentioned transistor or the like is 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, linen), synthetic fibers ( nylon, polyurethane, polyester) or regenerated fiber (acetate, cupra, These include polyester (including 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. Formation of resistors, manufacturing of durable devices, imparting heat resistance, lightening or thinning 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 shall be possible to do so.

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

[0135] The light emitting device may be a passive matrix light emitting device or an active matrix light emitting device. The light-emitting device described in this embodiment may be a light-emitting device. Optical 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 the light emitting device, and FIG. 6B is a view showing the light emitting device as seen from the dashed line A in FIG. 6A. 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 includes a pixel section 602 provided on an element substrate 601 and a driver circuit section (source line driver circuit) 6 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 sealing material 605. It is sealed between 601 and a sealing substrate 606 .

[0138] Also, on the element substrate 601, a driving circuit section 603, and driving circuit sections 604a and 604b are provided. external signals (e.g., video signals, clock signals, start signals, or reset signals) 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. Although only the FPC is shown here, this FPC also 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 an FPC or PWB is attached to it. It shall be.

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

[0140] The driving circuit section 603 is exemplified by a configuration in which an FET 609 and an FET 610 are combined. The driving circuit section 603 is a transistor of a single polarity (either N-type or P-type). It may be formed by 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 the figure shows an integrated driver, 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 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 FETs, a switching FET 611 and a current control FET 612. Although an example in which the pixel unit 602 is configured using ET has been described, the present invention is not limited to this. For example, The pixel portion 602 may be a combination of three or more FETs and a capacitor element.

[0142] The FETs 609, 610, 611, and 612 may be, for example, staggered or inverted staggered transistors. Transistors can be applied. Examples of semiconductor materials that can be used include semiconductors from Group 13 (gallium, etc.) and Group 14 (silicon, etc.). Semiconductors such as elemental semiconductors, compound semiconductors, oxide semiconductors, and organic semiconductor materials can be used. The crystallinity of the semiconductor material is not particularly limited. For example, it may be an amorphous semiconductor film or 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 energy gap is 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. By using an oxide semiconductor material, the off-state current of a transistor can be reduced.

[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 upper or lower end of the insulator 614 is formed with a curved surface. By forming the shape of the insulator 614 as described above, the upper layer of the insulator 614 For example, the material of the insulator 614 can be 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 stacked 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, the layer 5 may 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 together. The first electrode (anode) 613, the EL layer 615, and the The material used for the second electrode (cathode) 616 is the material shown in Embodiment 2. Although not shown here, the second electrode (cathode) 616 is an external input terminal. It is electrically connected to an FPC 608.

[0147] In addition, although only one light emitting element 617 is shown in the cross-sectional view of FIG. 6B, the pixel portion 6 02, a plurality of light-emitting elements are arranged in a matrix. 2, light-emitting elements that can emit three types 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 emits three kinds of light (R, A light-emitting element that can emit the above-mentioned several types of light is added to a light-emitting element that can emit G and B light. 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 obtained. In addition, by combining quantum dots, the luminous efficiency is improved and power consumption is reduced. It may also be placed.

[0148] Furthermore, by bonding a sealing substrate 606 to the element substrate 601 with a sealing material 605, A space 618 surrounded by the element substrate 601, the sealing substrate 606, and the sealant 605 contains a light-emitting element. The space 618 is filled with an inert gas (nitrogen or argon). The present invention also includes a configuration in which the cavity is filled with a sealing material 605, in addition to a configuration in which the cavity is filled with a gas such as argon.

[0149] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is desirable that these materials be 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, aluminum, polyester, or acrylic can be used. When glass frit is used as the sealing material, it is necessary to use a glass frit between the element substrate 601 and the sealing material from the viewpoint of adhesiveness. 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 completed by applying a light-emitting device which is one embodiment of the present invention will be described. An example of this will be described with reference to FIG.

[0153] As an electronic device to which a light emitting device is applied, for example, 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), portable game consoles, personal digital assistants, audio playback devices, large game machines such as pachinko 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 of one embodiment of the present invention can be used for the display portion 7103. In addition, the 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 using the remote control operation device 7110. The channel and volume can be controlled by the 7109, and the information displayed on the display 7103 is In addition, the remote control unit 7110 can be used to operate the video. A display unit 7107 for displaying information output from 7110 may be provided.

[0156] The television device 7100 is configured to include a receiver, a modem, etc. It is possible to receive more general television broadcasts, and also to receive them by wire or wirelessly via a modem. By connecting to a communication network, it can be transmitted in one direction (sender to receiver) or two directions (transmit to receiver). 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 of 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 smartwatch, which includes a housing 7302, a display panel 7304, and operation buttons. The connectors 7311, 7312, the connection terminal 7313, the band 7321, the 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 that indicates the time, other icons, The display portion 7304 can display a touch sensor (an input device). The touch panel (input / output device) may be mounted.

[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, Functions such as calendar, date or time display, various software (programs) It has the functions of controlling processing by wireless communication, and It has the function of connecting to a data network, and the function of transmitting or receiving various data using wireless communication. The function of reading out the program or data recorded on the recording medium and displaying it on the display unit. It can have functions such as:

[0161] In addition, a speaker, a sensor (force, displacement, position, velocity, acceleration, angular velocity) Degrees, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, electricity Includes functions to measure pressure, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared. 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). 400 includes a housing 7401, a display unit 7402, a microphone 7406, a speaker 7405, a camera, and the like. The device is equipped with a camera 7407, an external connection section 7404, and operation buttons 7403. When a light-emitting device is manufactured by forming a light-emitting element according to one embodiment 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 can be displayed by touching a display portion 7402 with a finger or the like. You can also make a call or write an email using the 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 mainly displays images. The first mode is a display mode, and the second mode is an input mode that mainly inputs information such as characters. This is a display + input mode that combines two modes: display mode and input mode.

[0165] For example, when making a call or creating an email, the display unit 7402 is used to input characters. This is the main character input mode, and you can 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's nice.

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

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

[0168] In the input mode, the optical sensor of the display unit 7402 detects a signal and displays it. If there is no input by touch operation on 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 device with your palm or fingers and capturing an image of your palm print or fingerprint, you can authenticate your identity. 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 capture images of finger veins, palm veins, etc.

[0170] Furthermore, as another configuration of a mobile phone (including a smartphone), Fig. 7(D'-1) and Fig. It can also be applied to a mobile phone having a structure such as 7(D'-2).

[0171] In addition, when the structure is as shown in Figure 7(D'-1) or Figure 7(D'-2), character information and Image information and the like are 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 screen 7502(1) and 7502(2). With this structure, you can keep the mobile phone in your breast pocket. Uses text information and image information displayed on the second page 7502(1), 7502(2), etc. The person can easily verify this.

[0172] 8(A) to 8(C) show a foldable mobile information terminal 9310. 8(B) shows the portable information terminal 9310 in an unfolded state. The mobile information terminal 9310 is in the process of changing from one folded state to the other. 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.

[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 two housings 9315 are bent to open the mobile information terminal 9310. The light-emitting device of one embodiment of the present invention can be reversibly transformed from a folded state to a folded state. It can be used for the display panel 9311. The display area of the display panel 9311 is This is a display area located on the side of the portable information terminal 9310 in a folded state. You can display information icons and shortcuts to frequently used apps and programs. This allows you to check information and launch apps smoothly.

[0174] In this manner, an electronic device can be obtained by applying the light-emitting device which is one embodiment of the present invention. In addition, the applicable electronic devices are not limited to those shown in this embodiment, but can be used in any field. It 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. By using a housing having a curved surface, the light emitting area has a housing, a cover, or a support base. A lighting device 8002 can also be formed. The element is thin film-like, and there is a high degree of freedom in the design of the housing. Furthermore, a large lighting device 8003 can be installed on the wall of the room. It's okay to do that.

[0178] In addition, by using a light emitting device on the surface of a table, it is possible to provide a lighting device that functions as a table. The light emitting device can be used as a light emitting device 8004. This allows the lighting device to function 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 described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. It is possible. [Example]

[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}dibene Synthesis of 2PCCzPDBq (Structural formula (100)) The structure of 2PCCzPDBq is shown below.

[0182] [ka]

[0183] <Synthesis of 2PCCzPDBq> First, 1.0 g (2.8 m) 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- 23 mg (0.10 mmol) of phosphate was added to a 200 mL three-neck flask and mixed. 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 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 minutes under a nitrogen atmosphere. 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 approximately 400 mL of hot toluene, and the solution was filtered through Celite and aluminum. The filtrate was concentrated and the resulting solid was recrystallized with toluene. As a result, 1.6 g of the target yellow powder was obtained in a yield of 80%.

[0185] The target product, 1.4 g of yellow powdery solid, was purified by train sublimation. The conditions for sublimation purification were a pressure of 3.8 Pa and argon gas flow rate of 10 mL / min. After sublimation purification, a yellow glassy solid of 2PCCzPDBq was obtained. The synthesis scheme for this step is shown in (a-1) below.

[0186] [ka]

[0187] Nuclear magnetic resonance spectroscopy ( 1 H-NMR analysis 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). This shows the enlarged view of the range of 2PCCzPDBq (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 and emission spectra of the toluene solution of 2PCCzPDBq are shown in Figure 11. The absorption and emission spectra of the thin film are shown in Figure 12. An infrared-visible spectrophotometer (V550 model, 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 placing only toluene in a quartz cell. The absorption spectrum of the thin film is shown as a function of the absorption spectrum of the quartz substrate. The absorption spectrum from which the spectrum was subtracted is shown.

[0190] As can be seen from 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 thickness of the 2PCCzPDBq thin film is 209 nm, 258 nm, 307 nm, and 336 nm. The absorption peaks are observed at 396 nm and 502 nm (excitation wavelength). The length was 396 nm. [Example]

[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}dibene Synthesis of 2mPCCzPDBq (Structural formula (101)) The structure of 2mPCCzPDBq is shown below.

[0192] [ka]

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

[0194] Next, bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd( 29 mg (0.050 mmol) of dba)2) 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 approximately 400 mL of hot toluene, and the solution was filtered through Celite and aluminum. The filtrate was concentrated and the resulting solid was recrystallized with toluene. As a result, 2.8 g of the target yellow powder was obtained in a yield of 79%.

[0195] The target product, 2.2 g of yellow powdery solid, was purified by sublimation using the train sublimation method. The conditions for sublimation purification were a pressure of 2.5 Pa and argon gas flow rate of 10 mL / min. After sublimation purification, 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 synthesis scheme for this step is shown in (b-1) below. .

[0196] [ka]

[0197] Nuclear magnetic resonance spectroscopy ( 1 H-NMR analysis 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) from 7.0 (ppm) to 10 (ppm). This shows 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 1)) was found to be 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 and emission spectra of 2mPCCzPDBq in toluene are shown in Figure 1. The absorption and emission spectra of the thin film are shown in Figure 15. An ultraviolet-visible spectrophotometer (V550 model, manufactured by JASCO Corporation) was used. The spectra were measured by placing a toluene solution of 2mPCCzPDBq in a quartz cell. The film spectrum was measured by depositing 2mPCCzPDBq onto a quartz substrate. The absorption spectrum of the toluene solution was measured by placing only toluene in a quartz cell. The absorption spectrum of the thin film is shown subtracted from that of the quartz substrate. The absorption spectrum from which the absorption spectrum of

[0200] As shown in Figure 14, the toluene solution of 2mPCCzPDBq exhibits absorption 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 208nm, 257nm, 308nm, 36 Absorption peaks are observed around 1 nm and 379 nm, and the emission wavelength peak is 515 nm (excitation wavelength). The wavelength was 380 nm. [Example]

[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}dibene 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- 34 mg (0.10 mmol) of phosphate was added to a 200 mL three-neck flask and mixed. 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 degassed by stirring.

[0204] Next, bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd( 24 mg (0.042 mmol) of dba)2 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 approximately 400 mL of hot toluene, and the solution was filtered through Celite and aluminum. The filtrate was concentrated and the resulting solid was recrystallized with toluene. As a result, 2.5 g of the target yellow powder was obtained in a yield of 84%.

[0205] The target product, 2.0 g of yellow powdery solid, was purified by train sublimation. The conditions for sublimation purification were a pressure of 3.7 Pa and argon gas flow rate of 10 mL / min. After sublimation purification, the yellow glass of 2PCCzPDBq-02 was obtained. 1.7 g of a solid was obtained 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 ( 1 H-NMR analysis 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) from 7.0(ppm) to 10(ppm). This shows 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 found to be 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 2PCCzPDBq-02 in toluene were The absorption spectrum and emission spectrum of the thin film are shown in Figure 17 and Figure 18, respectively. An ultraviolet-visible spectrophotometer (V550 model, manufactured by JASCO Corporation) was used for the measurement of the toluene solution. The spectrum was measured by placing a toluene solution of 2PCCzPDBq-02 in a quartz cell. The thin film spectrum was obtained by depositing 2PCCzPDBq-02 onto a quartz substrate. The absorption spectrum of the toluene solution was measured by placing only toluene in a quartz cell. The absorption spectrum of the thin film is shown in Fig. 1, and the absorption spectrum of the thin film is shown in Fig. 2. 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). Also, from Figure 18, the thin film of 2PCCzPDBq-02 has 209 nm, 257 nm, and 311 nm. Absorption peaks are observed at 326 nm, 351 nm, and 389 nm, and the emission wavelength peaks are The wavelength was 473 nm (excitation wavelength 396 nm). [Example]

[0211] <Synthesis Example 4> In this example, 2-{3-[2-(N-phenyl-9H-carbazoline]-2-methyl-2-(2-phenyl-9H-carbazoline)-2-(2-phenyl-9H-carbazoline)-2-methyl ... (3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quino Synthetic method 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 m) of 2-(3-chlorophenyl)dibenzo[f,h]quinoxaline mol), 2-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole 2.0g (5.0mmol), sodium tert-butoxide 0.96g (10mm ol), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (SP 41 mg (0.10 mmol) of HOs was placed in a 200 mL three-neck flask and mixed. The atmosphere was replaced with nitrogen. 25 mL of mesitylene was added to this mixture, and the flask was placed under reduced pressure. The mixture was degassed by stirring.

[0214] Next, bis(dibenzylideneacetone)palladium(0) (abbreviation: Pd( 29 mg (0.050 mmol) of dba)2) 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 approximately 400 mL of hot toluene, and the solution was filtered through Celite and aluminum. The resulting filtrate was concentrated to give a solid. The product was recrystallized from toluene to obtain 3.1 g of a white powder, which was the target substance, 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 argon gas flow rate of 5.0 mL / min. After sublimation purification, the yellow glass of 2mPCCzPDBq-02 was obtained. 2.0 g of a powdery solid was obtained with a recovery rate of 65%. The synthesis scheme for this step is shown below (d-1). Shown below.

[0216] [ka]

[0217] The white powdery solid obtained in the above step was analyzed by nuclear magnetic resonance spectroscopy ( 1 H-NMR analysis 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) from 7.0(ppm) to 10(ppm). This shows the 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. For the measurement, an ultraviolet-visible spectrophotometer (V550 model, manufactured by JASCO Corporation) was used. The spectrum was measured by placing a toluene solution of 2mPCCzPDBq-02 in a quartz cell. The thin film spectrum was obtained by depositing 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 obtained by subtracting the absorption spectrum measured with the filter is shown in the figure. 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 exhibits peaks at 281 nm, 305 nm, and 3 Absorption peaks are observed 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, and the emission wavelength peak was 484 nm (excitation wavelength 381 nm). [Example]

[0221] In this example, a development method using a dibenzo[f,h]quinoxaline derivative, which is one embodiment of the present invention, was The light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3 were fabricated. This 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 sputtering to form a first electrode 1101 that functions as an anode. The film thickness was 110 nm and the electrode area was 2 mm x 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 treated with UV ozone. This was done for 370 seconds.

[0226] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170° C. for 30 minutes in the heating chamber of the device, the substrate 1100 was 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 device was fixed to a holder provided in the device. In this example, the EL layer 11 was formed by vacuum deposition. 02, which comprises a hole injection layer 1111, a hole transport layer 1112, a light-emitting layer 1113, and an electron transport layer The case where the insulating layer 1114 and the 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 (by mass). A hole injection layer 1111 was formed on the electrode 1101. The film thickness was set to 20 nm. is a vapor 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. In the case of the light-emitting element 1, 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- Fluoren-2-amine (abbreviation: PCBBiF), (acetylacetonato)bis(6-te 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 evaporation 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 SiO 2 film 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), and After forming a 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'-(dibenzothiophen-4-yl)biphene 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 After co-evaporation to a thickness of 20 nm, 2mDBTBPD Bq-II:PCBBiF:[Ir(tBuppm)2(acac)]=0.8:0.2 : 0.05 (mass ratio), and a layered structure was formed with a thickness of 20 nm. 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 m thick film was formed on the light-emitting layer 1113. After depositing 20 nm of PCCzPDBq, bathophenanthroline (abbreviation: Bphen) An electron transport layer 1114 was formed by vapor deposition of 10 nm. In this case, 20 nm of 2mDBTBPDBq-II was deposited on the light-emitting layer 1113, and then the By depositing phenanthroline (abbreviation: Bphen) to 10 nm, an electron transport layer 111 4 was formed.

[0234] Furthermore, lithium fluoride is deposited on the electron transport layer 1114 at 1 nm to form a 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 3 was obtained. In the above-mentioned deposition process, the deposition was all carried out by the resistance heating method.

[0236] The device structures of the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3 obtained above 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 around the device). The coating was then subjected to UV treatment and heat treatment 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 (an atmosphere maintained at 25°C). The results are shown in Figures 23 to 26. show.

[0240] Also, 1000 cd / 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] Furthermore, the light-emitting element 1, the light-emitting element 2, and the comparative light-emitting element 3 were each supplied with 2.5 mA / cm 2 current density of The emission spectrum when a current was applied is shown in FIG. 27. Both the light-emitting element 2 and the comparative light-emitting element 3 have the structure [Ir(tBuppm)2(acac)] The spectrum showed a peak at around 546 nm, which was due to the

[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 100%. The horizontal axis shows the brightness (%), and the horizontal axis shows the driving time (h) of the device. 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 element 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 the reliability test are shown in Figure 28(B). The vertical axis is the voltage change. The horizontal axis shows the amount of light emitted (V), and the horizontal axis shows the operation time of the element (h). The voltage rise of the light-emitting 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, looking at the amount of voltage rise after approximately 500 hours of operation, the comparative light-emitting element 3 The voltage of the light-emitting element 1 was about 0.05 V, and the voltage of the light-emitting element 2 was about 0.0 2V. 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 significant 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 significantly different from the single films of PCBBiF and dibenzoquinoxaline compounds. (This is because it emits yellow-green light with a longer wavelength than the BiF monolayer.) HOM of 2, 2mPCCzPDBq, 2mDBTBPDBq-II, and PCBBiF 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 set to 0.4 eV or less, more preferably 0.3 eV or less. It is clear that the following is important.

[0250] 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 second organic compound The HOMO levels of PCBBiF and the first organic compound (2mPCCzPDBq-02 or 2mPCCzPDBq) is located between the 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. . [Example]

[0251] In this example, a development method using a dibenzo[f,h]quinoxaline derivative, which is one embodiment of the present invention, was An optical element 4 was fabricated. The configuration of the light-emitting element was determined by using FIG. 22 shown in Example 5. The chemical formulas of the materials used in this example 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 sputtering to form a first electrode 1101 that functions as an anode. The film thickness was 110 nm and the electrode area was 2 mm x 2 mm.

[0254] Next, as a pretreatment for forming the light emitting element 4 on the substrate 1100, the surface of the substrate 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 pressure has been reduced to about 100 Pa. After vacuum baking at 170° C. for 30 minutes in the heating chamber of the device, the substrate 1100 was 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 device was fixed to a holder provided in the device. In this example, the EL layer 11 was formed by vacuum deposition. 02, which comprises a hole injection layer 1111, a hole transport layer 1112, a light-emitting layer 1113, and an electron transport layer The case where the insulating layer 1114 and the 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 to form DBT3P-I The first electrode was formed by co-evaporation in a ratio of I:molybdenum oxide=4:2 (mass ratio). A hole injection layer 1111 was formed on the layer 1101. The thickness of the layer was 20 nm. It is a vapor 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-chlor) benzol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine( Abbreviation: PCBBiF), (acetylacetonato)bis(4,6-diphenylpyrimidinate) ) Iridium(III) (abbreviation: [Ir(dppm)2(acac)]) PDBq-02:PCBBiF:[Ir(dppm)2(acac)]=0.7:0.3 :0.05 (mass ratio) to form a 20 nm thick film, and then 2PCCzP DBq-02:PCBBiF:[Ir(dppm)2(acac)]=0.8:0.2: The layer structure was formed by co-evaporating the material to a mass ratio of 0.05 and forming a film thickness of 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 to 20 nm on the light-emitting layer 1113, and then The electron transport layer 1114 is formed by depositing 10 nm of benzophenone (abbreviation: Bphen). Formed.

[0261] Furthermore, lithium fluoride is deposited on the electron transport layer 1114 at 1 nm to form a 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 cases, the deposition was carried out using a resistance heating method.

[0263] The element structure of the light-emitting element 4 obtained as described above 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 exposure to the atmosphere. (Specifically, sealing material was applied around the device, UV treatment was performed, and the device was sealed at 80°C.) (Then, heat treatment was carried out for 1 hour.)

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

[0267] Also, 1000 cd / 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] Furthermore, 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 Figure 33, the light-emitting element 4 is [Ir(dppm)2(acac)] The spectrum showed a peak at around 581 nm, which was due to the

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

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

[0272] The results of measuring the amount of voltage change during the reliability test are shown in Figure 34(B). The vertical axis is the voltage change. The horizontal axis shows the amount of light emitted (V), and the horizontal axis shows 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 voltage rise after this is about 0.01 V for the light-emitting element 4. 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 0.06V. That is, the voltage rise of the light-emitting element 4 is suppressed to about one-sixth of that of 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. (This is because the 2PCCzPDB emits green light with a longer wavelength than the PCBBiF single film.) The HOMO level of q-02 is −5.68 eV. 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] 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 second organic compound HOMO levels of PCBBiF and the first organic compound (2PCCzPDBq-02) This means that the hole is transported not only to the second organic compound but also to the This is important from the viewpoint of injecting a part of the first organic compound into the second organic compound. [Example]

[0275] <Synthesis Example 5> In this example, a synthetic 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]biphenyl-3 -yl}dibenzo[f,h]quinoxaline (abbreviated as 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-9-yl]biphenyl-3-yl}dibenzo[f,h]quinoxaline (abbreviated as 2m 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) were added to a 100mL three-neck flask, mixed, and the flask was purged with nitrogen. To this mixture, 22 mL of mesitylene was added, and the flask was placed under reduced pressure and stirred. The mixture was degassed with .

[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 This mixture was stirred at 150°C for 23 hours under a nitrogen stream. Water and toluene were added, and the aqueous layer of the obtained filtrate was extracted with toluene. The extracted solution 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 resulting 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 suction filtered through a stack of celite and alumina. The filtrate was concentrated. A brown oil was obtained, which 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 66g, 18% yield.

[0279] The yellow powdery solid (0.66 g) obtained was purified by sublimation using the train sublimation method. The conditions for sublimation purification were a pressure of 2.6 Pa and argon gas flow rate of 5 mL / min. After sublimation purification, 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 ( 1 H-NMR analysis The results are shown below. 1 The H-NMR charts are shown in Figures 35(A) and 35(B). 35(B) is the horizontal axis (δ) of Figure 35(A) from 7.0 (ppm) to 10 (ppm). This shows the enlarged view of the range of 2-{3'-[3- (N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]bi Phenyl-3-yl}dibenzo[f,h]quinoxaline (abbreviated as 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). [Example]

[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)), comparative material 2-[3-(9H-cal 2mDBTP Comparison of comparative light-emitting element 6 using comparative material 2mCzPDBq 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] <Fabrication 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 fabricated in this example are shown below. 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 (a sealant was applied around the device). (The film is then sealed with UV treatment and heat treatment at 80°C for 1 hour.)

[0288] <Operation Characteristics of Light-Emitting Device 5, Comparative Light-Emitting Device 6, and Comparative Light-Emitting Device 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 (an 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, 1000 cd / 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 supplied with an emitting current of 2.5 mA / cm 2 Current The emission spectrum when a current was applied at a density is shown in FIG. 40. 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 were all [Ir(tBuppm)2(ac The spectrum showed a peak at around 544 nm, which was attributed to the ion beam ionization reaction (ion beam ionization reaction).

[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 represents the standard deviation when the initial luminance is 100%. The horizontal axis shows the rated luminance (%), and the horizontal axis shows the device operation time (h). Brightness: 5000cd / m 2The light-emitting element 5 and the comparative light-emitting element 6 were measured under a constant current density condition. , 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 Comparative light-emitting element 6 using TPDBq-II and comparative light-emitting element 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 the reliability test are shown in Figure 41(B). The vertical axis is the voltage change. The horizontal axis shows the amount of light emitted (V), and the horizontal axis shows 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 amount of voltage rise after approximately 1000 hours of operation, the comparative light-emitting element 6 The light-emitting element 5 had a voltage of about 0.0 V, the comparative light-emitting element 7 had a voltage of about 0.50 V, and the light-emitting element 5 had a voltage of about 0.0 V. 4 V. In other words, the voltage increase amount of the light-emitting element 5 is 4 V, compared with the comparative light-emitting element 6 and the comparative light-emitting element 7. is significantly suppressed, which is a significant effect.

[0296] In addition, 2mPCCzPDBq, 2mDBTPDBq-II, and 2mCzPDBq are all , and PCBBiF form exciplexes (these dibenzoquinoxaline compounds and PCBB The mixed films with PCBBiF were all more effective than the single dibenzoquinoxaline compound films and PCBBiF single films. (This is because it emits yellow-green light with a longer wavelength than 2mPCCzPDBq and 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 was calculated. The results are summarized in Table 8.

[0298] [Table 8]

[0299] From this result, ΔE HOMO is set to 0.4 eV or less, more preferably 0.3 eV or less. It is clear that the following is important.

[0300] 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 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 compounds in part 1. [Example]

[0301] In this example, the dibenzo[f,h]quinoxaline derivative 2mPCC, which is one embodiment of the present invention, Light-emitting device 8 was fabricated using zBPDBq. 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 fabricated 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 exposure to the atmosphere. (Sealing material was applied around the element, and UV treatment was performed during sealing, and the device was sealed at 80°C.) Heat treated for 1 hour).

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

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

[0308] Also, 1000 cd / m 2 The main initial characteristics 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 supplied with 2.5 mA / cm 2 The emission spectrum when a current is applied at a current density of As shown in Figure 46, the light-emitting element 8 contains [Ir(dppm)(acac)] The spectrum showed a peak at around 584 nm, which was due to the [Example]

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

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

[0313] In the storage test in this example, 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 (in an atmosphere maintained at 25°C).

[0314] First, FIG. 47 shows the voltage-current characteristics of the light-emitting element 1A when stored at 100° C. for a predetermined time. 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, FIG. 49 shows the voltage-current characteristics of the light-emitting element 2A when stored at 100° C. for a predetermined time. The luminance-external quantum efficiency characteristics are shown in FIG. 50. In FIG. 49, the horizontal axis represents voltage (V) and the vertical axis represents 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 comparative light-emitting element 3A after storage at 100°C for a specified time are shown in Figure 51. The luminance vs. external quantum efficiency characteristics are shown in Figure 52. In Figure 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 In Figure 52, 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, FIG. 53 shows the voltage-current characteristics of the light-emitting element 4A when stored at 100° C. for a predetermined time. The luminance-external quantum efficiency characteristics are shown in FIG. 54. In FIG. 53, the horizontal axis represents voltage (V) and the vertical axis represents 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, FIG. 55 shows the voltage-current characteristics of the light-emitting element 8A when stored at 100° C. for a predetermined time. The luminance-external quantum efficiency characteristics are shown in Figure 56. In Figure 55, the horizontal axis represents voltage (V) and the vertical axis represents 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 8B were stored at 100°C for 500 hours, but the voltage-current characteristics and There is little change in brightness-external quantum efficiency characteristics, and there is little deterioration in device characteristics due to high-temperature storage. On the other hand, as can be seen from FIGS. 51 and 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. As can be seen from FIG. 51, the comparative light-emitting element 3A lost its initial characteristics after 100 hours. As shown in Figure 52, the insulating properties of the Therefore, it is clear 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 the presence of the material is dramatically improved. [Explanation of symbols]

[0320] 100 luminescent 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)th EL layer 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 PCB 502 FET 503 First electrode 504 Bulkhead 505 EL layer 506R, 506G, 506B, 506Y Light-emitting area 507R, 507G, 507B, 507Y Light-emitting elements 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 Insulators 615 EL layer 616 Second electrode (cathode) 617 Light-emitting element 618 Space 1100 board 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 Housing 7103 Display section 7105 Stand 7107 Display section 7109 Operation key 7110 Remote control device 7201 Main unit 7202 Case 7203 Display section 7204 keyboard 7205 External connection port 7206 Pointing Device 7302 Housing 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 Housing 7402 Display section 7403 Operation buttons 7404 External connection part 7405 Speaker 7406 Microphone 7407 Camera 8001 Lighting equipment 8002 Lighting equipment 8003 Lighting equipment 8004 Lighting equipment 9310 Mobile Information Terminal 9311 Display Panel 9313 Hinge 9315 Housing

Claims

[Claim 1] an EL layer between an anode and a cathode, the EL layer has a light-emitting layer, the light-emitting layer includes a first organic compound having an electron-transporting property and a hole-transporting property, a second organic compound having a hole-transporting property, and a light-emitting substance; the first organic compound and the second organic compound are a combination that forms an exciplex, a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound; a difference between the HOMO level of the first organic compound and the HOMO level of the second organic compound being 0.4 eV or less;

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