Crystals of phenanthroline derivatives, method for producing the same, and light-emitting device using the same

Abstract

An object of the present invention is to provide a crystal of a phenanthroline derivative having high chemical purity and a small amount of residual solvent suitable for use as a material for a light-emitting element, and a method for producing the same, and to provide a crystal of a phenanthroline derivative (referred to as B-type crystal) having the structure represented by the general formula (1) and having peaks at diffraction angles 2θ (°) of 6.7 ± 0.2, 8.2 ± 0.2, 13.7 ± 0.2, 17.7 ± 0.2, and 22.2 ± 0.2 in powder X-ray diffraction, and a crystal of a phenanthroline derivative (referred to as C-type crystal) having the structure represented by the general formula (1) and having peaks at diffraction angles 2θ (°) of 5.0 ± 0.2, 7.5 ± 0.2, 8.7 ± 0.2, 12.5 ± 0.2, and 17.3 ± 0.2 in powder X-ray diffraction. Further, provided is a crystal of a phenanthroline derivative having the structure represented by the general formula (1) and having peaks at diffraction angles 2θ (°) of 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2, 20.0 ± 0.2, and 23.6 ± 0.2 in powder X-ray diffraction, which is suitable as a crystal for obtaining a C-type crystal. (X represents a phenylene group or a naphthylene group.)

Description

Technical Field

[0001] The present invention relates to crystals of phenanthroline derivatives and a method for producing the same. The phenanthroline derivatives are compounds useful as luminescent element materials that can be used in fields such as display elements, flat panel displays, backlights, lighting, interior decorations, signs, billboards, electronic cameras, and optical signal generators. Background Art

[0002] Regarding phenanthroline derivatives, heretofore, for example, a luminescent element material containing a phenanthroline derivative represented by the following general formula (1) has been disclosed, and as a method for producing the same, a method of reacting phenyllithium with 1,3-bis(1,10-phenanthrolin-2-yl)benzene and then performing oxidation has been disclosed; a method of reacting 1,3-dibromobenzene with tert-butyllithium and then reacting 2-phenyl-1,10-phenanthroline and then performing oxidation (for example, refer to Patent Document 1).

[0003] In addition, as a method for producing a nitrogen-containing aromatic ring derivative containing a phenanthroline derivative represented by the following general formula (1), a method of dilithiating a dibromo aromatic compound using n-butyllithium or sec-butyllithium, adding a nitrogen-containing aromatic ring derivative, and then performing oxidation has been proposed (for example, refer to Patent Document 2).

[0004] In addition, regarding a polymer electrolyte composition including a polymer containing an ionic group, an organophosphorus-based additive, and a nitrogen-containing heteroaromatic ring-based additive, as a method for producing the nitrogen-containing heteroaromatic ring-based additive, a method of reacting 8-amino-7-quinolinecarboxaldehyde with 1,3-diacetylbenzene and potassium hydroxide, then reacting it with phenyllithium, and then performing oxidation and recrystallization purification has been disclosed (for example, refer to Patent Document 3).

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-281390

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2008-189660

[0009] Patent Document 3: International Publication No. 2015 / 156228 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] Generally, organic compounds have multiple solid states such as amorphous and crystalline states. Similarly, phenanthroline derivatives also have polymorphs. Even if the crystal structure of a phenanthroline derivative has the same structure in the molecular unit, due to different molecular packing patterns, it affects chemical and physical properties and operability. For example, when using the above-mentioned phenanthroline compound as a light-emitting element material, sublimation purification is generally carried out, but there is no disclosure in Patent Document 1 that can clarify its solid state. The phenanthroline derivative obtained by the conventional manufacturing method as described in Patent Document 2 has a problem of insufficient chemical purity when used as a light-emitting element material even after sublimation purification due to low chemical purity. In addition, the manufacturing method disclosed in Patent Document 3 cannot clarify the crystal form, and solvent-containing crystals are formed according to the crystal form, with a large amount of residual solvent, so there is a problem of causing bumping during sublimation purification.

[0012] Therefore, an object of the present invention is to provide a crystal of a phenanthroline derivative with high chemical purity and a small amount of residual solvent, and a manufacturing method thereof.

[0013] Method for solving the problem

[0014] That is, the present invention is a crystal of a phenanthroline derivative having the structure represented by the general formula (1) and having peaks at diffraction angles 2θ (°) of 6.7 ± 0.2, 8.2 ± 0.2, 13.7 ± 0.2, 17.7 ± 0.2, and 22.2 ± 0.2, respectively, in powder X-ray diffraction. In addition, another aspect of the present invention is a crystal of a phenanthroline derivative having the structure represented by the general formula (1) and having peaks at diffraction angles 2θ (°) of 5.0 ± 0.2, 7.5 ± 0.2, 8.7 ± 0.2, 12.5 ± 0.2, and 17.3 ± 0.2, respectively, in powder X-ray diffraction. In addition, another aspect of the present invention is a crystal of a phenanthroline derivative having the structure represented by the general formula (1) and having peaks at diffraction angles 2θ (°) of 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2, 20.0 ± 0.2, and 23.6 ± 0.2, respectively, in powder X-ray diffraction, and this crystal is extremely suitable as a crystal for obtaining the C-type crystal described later.

[0015]

[0016] (In the general formula (1), X represents a phenylene group or a naphthylene group.)

[0017] Effects of the invention

[0018] The crystals of the phenanthroline derivative of the present invention have high chemical purity and a small amount of residual solvent. Therefore, it has the effect of suppressing bumping during sublimation purification. In addition, it has the effect of exhibiting high chemical purity and being suitable for use as a material for light-emitting elements after sublimation purification. Further, when a specific pyrromethene compound is used in combination, in the case of manufacturing a light-emitting element, the light-emitting element can be driven at a low voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The powder X-ray diffraction pattern of the B-type crystal of the phenanthroline derivative represented by the general formula (1) obtained in Example 1.

[0020] Figure 2 The figure showing the differential thermal analysis curve obtained by simultaneous differential thermal-thermogravimetric measurement of the B-type crystal of the phenanthroline derivative represented by the general formula (1) obtained in Example 1.

[0021] Figure 3 The powder X-ray diffraction pattern of the C-type crystal of the phenanthroline derivative represented by the general formula (1) obtained in Example 3.

[0022] Figure 4 The figure showing the differential thermal analysis curve obtained by simultaneous differential thermal-thermogravimetric measurement of the C-type crystal of the phenanthroline derivative represented by the general formula (1) obtained in Example 3.

[0023] Figure 5 The powder X-ray diffraction pattern of the E-type crystal of the phenanthroline derivative represented by the general formula (1) obtained in Example 6.

[0024] Figure 6 The figure showing the differential thermal analysis curve obtained by simultaneous differential thermal-thermogravimetric measurement of the E-type crystal of the phenanthroline derivative represented by the general formula (1) obtained in Example 6.

[0025] Figure 7 The powder X-ray diffraction pattern of the D-type crystal of the phenanthroline derivative represented by the general formula (1) obtained in Comparative Example 1.

[0026] Figure 8 The figure showing the differential thermal analysis curve obtained by simultaneous differential thermal-thermogravimetric measurement of the D-type crystal of the phenanthroline derivative represented by the general formula (1) obtained in Comparative Example 1.

[0027] Figure 9 The powder X-ray diffraction pattern of the amorphous form of the phenanthroline derivative represented by the general formula (1) obtained in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, the present invention will be described in detail. The inventions described in claims 1 to 3 in the claims are inventions of C-type crystals of phenanthroline derivatives. On the other hand, the invention described in claim 16 is an invention of E-type crystals of phenanthroline derivatives. Further, the inventions described in claims 17 to 19 are inventions of B-type crystals of phenanthroline derivatives. Furthermore, the inventions described in claims 12 to 15 are inventions of a manufacturing method for producing C-type crystals from E-type crystals. In addition, the invention described in claim 20 is an invention of a manufacturing method for producing B-type crystals.

[0029] The crystal of the phenanthroline derivative according to the first aspect of the present invention has a structure represented by the general formula (1) and has specific crystal forms having peaks at diffraction angles 2θ (°) of 6.7 ± 0.2, 8.2 ± 0.2, 13.7 ± 0.2, 17.7 ± 0.2, and 22.2 ± 0.2, respectively, in powder X-ray diffraction, and is referred to as B-type crystal in this specification.

[0030] In addition, the crystal of the phenanthroline derivative according to the second aspect of the present invention has a structure represented by the general formula (1) and has specific crystal forms having peaks at diffraction angles 2θ (°) of 5.0 ± 0.2, 7.5 ± 0.2, 8.7 ± 0.2, 12.5 ± 0.2, and 17.3 ± 0.2, respectively, in powder X-ray diffraction, and is referred to as C-type crystal in this specification.

[0031] Since the B-type crystal and C-type crystal of the phenanthroline derivative have high chemical purity and little residual solvent, bumping during sublimation purification can be suppressed. In addition, high chemical purity is exhibited, and it can be suitably used as a material for a light-emitting element after sublimation purification.

[0032]

[0033] In the above general formula (1), X represents a phenylene group or a naphthylene group. Among them, from the viewpoints of molecular weight and sublimation purification temperature, a phenylene group is preferred.

[0034] Examples of the phenanthroline derivative represented by the general formula (1) include substances having the structures shown below.

[0035]

[0036] Among them, 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene is preferred from the viewpoints of ease of synthesis, stability of the thin film, and the like.

[0037] Among the crystals of the phenanthroline derivative of the present invention, the crystal exhibited as the B-type crystal is a crystal having peaks at diffraction angles 2θ (°) of 6.7 ± 0.2, 8.2 ± 0.2, 13.7 ± 0.2, 17.7 ± 0.2, and 22.2 ± 0.2 in powder X-ray diffraction, and the crystal exhibited as the C-type crystal is a crystal having peaks at diffraction angles 2θ (°) of 5.0 ± 0.2, 7.5 ± 0.2, 8.7 ± 0.2, 12.5 ± 0.2, and 17.3 ± 0.2.

[0038] Here, the powder X-ray diffraction can be measured using a powder X-ray diffractometer under the following conditions. In addition, the measurement sample is prepared by filling the sample in a sample plate (material: silicon; depth: 0.2 mm) to make the surface of the sample flat.

[0039] X-ray source: CuKα ray

[0040] * Use a curved crystal monochromator (graphite)

[0041] Output: 40 kV / 50 mA

[0042] Divergence slit: 1 / 2°

[0043] Divergence longitudinal limiting slit: 5 mm

[0044] Scattering slit: 1 / 2°

[0045] Receiving slit: 0.15 mm

[0046] Detector: Scintillation counter

[0047] Scanning mode: 2θ / θ scanning, continuous scanning

[0048] Measurement range (2θ): 2 - 30°

[0049] Scanning speed (2θ): 20° / min

[0050] Counting step size (2θ): 0.04°.

[0051] The B-type crystal of the phenanthroline derivative of the present invention preferably has an endothermic peak in the range of 180 - 184 °C in simultaneous differential thermal - thermogravimetric measurement (hereinafter sometimes abbreviated as "TG-DTA"). Such an endothermic peak is one of the characteristics for clarifying the crystal form, and having an endothermic peak in the range of 180 - 184 °C means it is the above-mentioned B-type crystal. In addition, the C-type crystal of the phenanthroline derivative of the present invention preferably has an endothermic peak in the range of 243 - 247 °C in simultaneous differential thermal - thermogravimetric measurement. Having an endothermic peak in the range of 243 - 247 °C means it is the above-mentioned C-type crystal.

[0052] Here, TG-DTA can be measured using a TG-DTA apparatus under the following conditions, and the temperature at the peak shown in the DTA curve is taken as the endothermic peak.

[0053] Temperature rising rate: 5 °C / min

[0054] Atmosphere: Dry nitrogen (flow rate: 100 mL / min)

[0055] Specimen unit: Aluminum open unit

[0056] Amount of specimen: 5 - 15 mg.

[0057] The phenanthroline derivative represented by the general formula (1) can be produced, for example, by the method described in Japanese Patent Laid-Open No. 2008-189660. That is, after the dibromobenzene derivative is dilithiated with an alkyllithium, 2-phenyl-1,10-phenanthroline is allowed to act, and then oxidation is carried out, whereby the target phenanthroline derivative can be obtained.

[0058] The B-type crystal of the phenanthroline derivative represented by the general formula (1) of the first aspect of the present invention can be obtained, for example, by the following method, which has the following steps: a step (I) of dissolving the phenanthroline derivative represented by the general formula (1) in any form in a mixed solvent containing an aprotic polar solvent and an aromatic solvent and crystallizing it; and then a step (II) of dissolving the crystal obtained in step (I) in an ether solvent and crystallizing it.

[0059] Examples of the aprotic polar solvent include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; sulfone solvents such as sulfolane; urea solvents such as 1,3-dimethyl-2-imidazolidinone and N,N-dimethylpropyleneurea; nitrile solvents such as acetonitrile and propionitrile; pyridine solvents such as pyridine and 2-methylpyridine. Two or more of them can be used. Among them, amide solvents, sulfoxide solvents, and urea solvents are preferred, and 1,3-dimethyl-2-imidazolidinone is more preferred from the viewpoint of improving the recovery rate of the B-type crystal.

[0060] Examples of the aromatic solvent include benzene, chlorobenzene, anisole, toluene, xylene, isopropylbenzene, mesitylene, etc. Two or more of them can be used. Among them, anisole, toluene, and xylene are preferred, and toluene is more preferred from the viewpoint of improving the recovery rate of the B-type crystal.

[0061] In a mixed solvent containing an aprotic polar solvent and an aromatic solvent, from the viewpoint of improving the recovery rate of the B-form crystal, the content of the aromatic solvent is preferably 50 to 500 parts by weight, more preferably 100 to 300 parts by weight, relative to 100 parts by weight of the aprotic polar solvent.

[0062] In addition, in a mixed solvent containing an aprotic polar solvent and an aromatic solvent, other solvents other than the aprotic polar solvent and the aromatic solvent can be included in the mixed solvent as long as crystals of the phenanthroline derivative having the required diffraction angle can be obtained.

[0063] From the viewpoint of facilitating stirring, the amount of the above mixed solvent used is preferably 300 parts by weight or more, more preferably 500 parts by weight or more, relative to 100 parts by weight of the phenanthroline derivative represented by the general formula (1). On the other hand, from the viewpoint of improving the production efficiency per unit volume, the amount of the mixed solvent used is preferably 10,000 parts by weight or less, more preferably 3,000 parts by weight or less, relative to 100 parts by weight of the phenanthroline derivative represented by the general formula (1).

[0064] The order of adding the solvents in step (I) is not particularly limited. For example, an aprotic polar solvent can be added to the phenanthroline derivative represented by the general formula (1) and heated to dissolve it, and then an aromatic solvent can be added.

[0065] In step (I), as a method of dissolving the phenanthroline derivative represented by the general formula (1) in the mixed solvent, it is preferably dissolved by heating. From the viewpoint of quickly dissolving the phenanthroline derivative represented by the general formula (1), the heating temperature is preferably 50 °C or higher, more preferably 80 °C or higher. On the other hand, from an industrial viewpoint, the heating temperature is preferably 150 °C or lower, more preferably 130 °C or lower. It is not necessary to completely dissolve the phenanthroline derivative, but in the case of incomplete dissolution, the heating time is preferably set according to the solubility. In this case, the heating time is preferably 0.5 to 100 hours, more preferably 1 to 50 hours.

[0066] When dissolving by heating in step (I), it is preferably cooled in the crystallization step. From the viewpoint of improving the recovery rate of the B-form crystal, the cooling temperature is preferably -20 to 30 °C, more preferably -10 to 10 °C. The cooling rate is preferably 0.1 to 50 hours, more preferably 0.5 to 20 hours. During cooling, it can be stirred or allowed to stand.

[0067] Examples of the ether solvent include acyclic ethers such as diethyl ether, diisopropyl ether, cyclopentyl methyl ether, tert-butyl methyl ether, dimethoxyethane, and diethylene glycol dimethyl ether; tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-di Cyclic ethers such as alkanes, etc. Two or more of them can be used. Among them, cyclic ethers are preferred, and from the viewpoint of improving the recovery rate of B-type crystals, tetrahydrofuran is more preferably used.

[0068] From the viewpoint of facilitating stirring, the usage amount of the ether-based solvent is preferably 300 parts by weight or more, more preferably 500 parts by weight or more, relative to 100 parts by weight of the phenanthroline derivative represented by the general formula (1). On the other hand, from the viewpoint of improving the manufacturing efficiency per unit volume, the usage amount of the ether-based solvent is preferably 10,000 parts by weight or less, more preferably 3,000 parts by weight or less, relative to 100 parts by weight of the phenanthroline derivative represented by the general formula (1).

[0069] In step (II), as a method of dissolving the phenanthroline derivative represented by the general formula (1) in an ether-based solvent, it is preferably dissolved by heating. From the viewpoint of rapidly dissolving the phenanthroline derivative represented by the general formula (1), the heating temperature is preferably 40°C or higher, more preferably 60°C or higher. On the other hand, from an industrial viewpoint, the heating temperature is preferably 150°C or lower, more preferably 130°C or lower. It is not necessary to completely dissolve the phenanthroline derivative, but in the case of incomplete dissolution, the heating time is preferably set according to the solubility. In this case, the heating time is preferably 0.5 to 100 hours, more preferably 1 to 50 hours.

[0070] When dissolving by heating in step (II), it is preferable to perform cooling in the step of crystallizing it. The preferred ranges of the cooling temperature and the cooling rate are the same as in step (I).

[0071] In the step of crystallizing in step (II), B-type crystals of the phenanthroline derivative obtained in advance can be added as crystal seeds. In addition, a step of drying the obtained crystals can be further provided.

[0072] The C-type crystals of the phenanthroline derivative represented by the general formula (1) of the second aspect of the present invention can be obtained, for example, by the following method, which has the following steps: a step (I) of dissolving the phenanthroline derivative represented by the general formula (1) in any form in a mixed solvent containing an aprotic polar solvent and an aromatic solvent and crystallizing it; and then a step (III) of drying the crystals obtained by step (I) at 50°C or higher.

[0073] Examples of the aprotic polar solvent include the substances exemplified in the manufacturing method of the B-type crystals in the first aspect above. Among them, amide solvents, sulfoxide solvents, and urea solvents are preferred, and 1,3-dimethyl-2-imidazolidinone, N-methylpyrrolidone, and N,N-dimethylacetamide are more preferred from the viewpoint of improving the recovery rate of C-type crystals.

[0074] As the aromatic solvent, substances exemplified in the method for producing the B-type crystal of the first aspect above can be mentioned. Among them, anisole, toluene, and xylene are preferable, and anisole is more preferable from the viewpoint of improving the recovery rate of the C-type crystal.

[0075] In the mixed solvent containing an aprotic polar solvent and an aromatic solvent, from the viewpoint of improving the recovery rate of the C-type crystal, the content of the aromatic solvent is preferably 50 to 210 parts by weight, more preferably 100 to 205 parts by weight, relative to 100 parts by weight of the aprotic polar solvent.

[0076] In addition, in the mixed solvent containing an aprotic polar solvent and an aromatic solvent used herein, other solvents other than the aprotic polar solvent and the aromatic solvent can be included in the mixed solvent as long as crystals of the phenanthroline derivative having the required diffraction angle can be obtained.

[0077] From the viewpoint of facilitating stirring, the amount of the mixed solvent used is preferably 300 parts by weight or more, more preferably 500 parts by weight or more, relative to 100 parts by weight of the phenanthroline derivative represented by the general formula (1). On the other hand, from the viewpoint of improving the production efficiency per unit volume, the amount of the mixed solvent used is preferably 10,000 parts by weight or less, more preferably 3,000 parts by weight or less, relative to 100 parts by weight of the phenanthroline derivative represented by the general formula (1).

[0078] The order of adding the solvents in step (I) is not particularly limited. For example, the aprotic polar solvent can be added to the phenanthroline derivative represented by the general formula (1), heated to dissolve it, and then the aromatic solvent can be added.

[0079] In step (I), as a method of dissolving the phenanthroline derivative represented by the general formula (1) in the mixed solvent, it is preferable to dissolve it by heating. The preferable ranges of the heating temperature and the heating time are the same as those in step (I) of the method for producing the B-type crystal of the first aspect above.

[0080] When dissolving by heating in step (I), it is preferable to perform cooling in the step of crystallizing it. The preferable ranges of the cooling temperature and the cooling rate are the same as those in step (I) of the method for producing the B-type crystal of the first aspect above.

[0081] From the viewpoint of efficiently conducting polymorphic transformation, the drying temperature in step (III) is preferably 50°C or higher, more preferably 80°C or higher. On the other hand, from an industrial viewpoint, the drying temperature is preferably 150°C or lower, more preferably 130°C or lower. In addition, the drying in step (III) is preferably vacuum drying. From the viewpoint of rapidly removing residual solvents, the degree of vacuum in vacuum drying is preferably 666.6 Pa (5 mmHg) or lower.

[0082] In addition, the C-type crystal of the phenanthroline derivative represented by the general formula (1) can also be obtained, for example, by polymorphic transformation of a crystal of the phenanthroline derivative having the structure represented by the above general formula (1) and having peaks at diffraction angles 2θ (°) of 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2, 20.0 ± 0.2, and 23.6 ± 0.2 in powder X-ray diffraction (in this specification, referred to as the E-type crystal). The C-type crystal of the phenanthroline derivative represented by the general formula (1) can also be obtained by heating and drying a crystal other than the C-type crystal to conduct polymorphic transformation, but the temperature varies greatly depending on the crystal form. Among the crystal forms, the E-type crystal is preferred from an industrial viewpoint because polymorphic transformation can be carried out at a relatively low temperature to obtain the C-type crystal. In this case, it is preferred to obtain the E-type crystal in the above step (I) and obtain the C-type crystal by polymorphic transformation in the above step (III).

[0083] The E-type crystal of the phenanthroline derivative is effective as a precursor of the C-type crystal because it is easily transformed into the C-type crystal by heating and drying. The E-type crystal of the phenanthroline derivative preferably has an endothermic peak in the range of 94 to 98°C in simultaneous differential thermal - thermogravimetric measurement. Having an endothermic peak in such a temperature range means it is an E-type crystal. In addition, powder X-ray diffraction measurement and simultaneous differential thermal - thermogravimetric measurement can be carried out by the same methods as those described for the above B-type crystal and C-type crystal.

[0084] The E-type crystal of the phenanthroline derivative represented by the general formula (1) can be obtained, for example, by the following method, which has the following steps: a step (I) of dissolving the phenanthroline derivative represented by the general formula (1) in any form in a mixed solvent containing an aprotic polar solvent and an aromatic solvent and crystallizing it; and then a step (IV) of drying the crystal obtained through step (I) at a temperature lower than 50°C.

[0085] As aprotic polar solvents, mention may be made of the substances exemplified in the method for producing the B-type crystal of the first aspect described above. Among them, amide solvents, sulfoxide solvents, and urea solvents are preferred, and 1,3-dimethyl-2-imidazolidinone, N-methylpyrrolidone, and N,N-dimethylacetamide are more preferred from the viewpoint of improving the recovery rate of the C-type crystal.

[0086] As aromatic solvents, mention may be made of the substances exemplified in the method for producing the B-type crystal of the first aspect described above. Among them, anisole, toluene, and xylene are preferred, and anisole is more preferred from the viewpoint of improving the recovery rate of the C-type crystal.

[0087] In the mixed solvent containing an aprotic polar solvent and an aromatic solvent, from the viewpoint of improving the recovery rate of the C-type crystal, the content of the aromatic solvent is preferably 50 to 210 parts by weight, more preferably 100 to 205 parts by weight, relative to 100 parts by weight of the aprotic polar solvent.

[0088] In addition, also in the mixed solvent containing an aprotic polar solvent and an aromatic solvent used herein, other solvents other than the aprotic polar solvent and the aromatic solvent may be included in the mixed solvent as long as crystals of the phenanthroline derivative having the required diffraction angle can be obtained.

[0089] From the viewpoint of facilitating stirring, the amount of the mixed solvent used is preferably 300 parts by weight or more, more preferably 500 parts by weight or more, relative to 100 parts by weight of the phenanthroline derivative represented by the general formula (1). On the other hand, from the viewpoint of improving the production efficiency per unit volume, the amount of the mixed solvent used is preferably 10,000 parts by weight or less, more preferably 3,000 parts by weight or less, relative to 100 parts by weight of the phenanthroline derivative represented by the general formula (1).

[0090] The order of adding the solvents in step (I) is not particularly limited. For example, an aprotic polar solvent may be added to the phenanthroline derivative represented by the general formula (1) and heated to dissolve it, and then an aromatic solvent may be added.

[0091] In step (I), as a method for dissolving the phenanthroline derivative represented by the general formula (1) in the mixed solvent, it is preferably dissolved by heating. The preferred ranges of the heating temperature and the heating time are the same as those in step (I) of the method for producing the B-type crystal of the first aspect described above.

[0092] When dissolving by heating in step (I), it is preferably cooled in the step of crystallizing it. The preferred ranges of the cooling temperature and the cooling rate are the same as those in step (I) of the method for producing the B-type crystal of the first aspect described above.

[0093] From the viewpoint of rapidly removing the residual solvent, the drying temperature in step (IV) is preferably 10°C or higher, more preferably 20°C or higher. On the other hand, from the viewpoint of maintaining the crystal form, the drying temperature is preferably less than 50°C, more preferably 30°C or lower.

[0094] By subjecting the E-type crystal of the phenanthroline derivative represented by the general formula (1) obtained by the above method to polymorphic transformation, the C-type crystal can be obtained with high efficiency. As the step of subjecting it to polymorphic transformation, it is preferably 50°C or higher, more preferably 80°C or higher. On the other hand, since the E-type crystal undergoes polymorphic transformation at a lower temperature, from an industrial viewpoint, it is preferably 150°C or lower, more preferably 130°C or lower.

[0095] The B-type crystal or C-type crystal of the phenanthroline derivative represented by the general formula (1) of the present invention has extremely low residual solvent amount and extremely high chemical purity, and thus can be suitably used as a material for a light-emitting element. Since the B-type crystal or C-type crystal of the phenanthroline derivative of the present invention has high electron transport property and electron injection property, in a light-emitting element, it can be particularly suitably used for an electron transport layer, an electron injection layer, and a charge generation layer. Furthermore, in a light-emitting element in which the electron transport layer, the electron injection layer, or the charge generation layer contains the phenanthroline derivative of the B-type crystal or C-type crystal of the phenanthroline derivative of the present invention, since it has an extremely high layer with a chemical purity of 99.7% or more of the phenanthroline derivative that can be achieved by the B-type crystal or C-type crystal, the electron transport layer, the electron injection layer, or the charge generation layer can be a stable layer with little film quality change over time. In addition, even when a thermally activated delayed fluorescence material is used for the light-emitting layer, an external quantum efficiency of 7.0% or more can be exhibited.

[0096] In addition, since the B-type crystal or C-type crystal of the phenanthroline derivative of the present invention has extremely low residual solvent amount and extremely high chemical purity, the outgassing amount during the production of a light-emitting element is small, high-purity film formation can be performed, and a light-emitting element with high luminous efficiency can be obtained. In particular, since it can reduce the driving voltage and obtain high-efficiency light emission, it is suitable for a light-emitting element that includes a thermally activated delayed fluorescence material (sometimes referred to as a "TADF material") in the light-emitting layer.

[0097] Next, a light-emitting element using the B-type crystal or C-type crystal of the phenanthroline derivative represented by the general formula (1) of the present invention will be described in detail.

[0098] The light-emitting element of the present invention has a function of converting electric energy into light. Here, as the electric energy, direct current is mainly used, but pulse current and alternating current can also be used. The current value and voltage value are not particularly limited, and the characteristic values required vary depending on the purpose of the element. However, from the viewpoints of power consumption and lifespan of the element, it is preferable to obtain high brightness at a low voltage. In addition, from the viewpoint of improving color purity, the half-width of the emission spectrum obtained by energization is preferably 60 nm or less, more preferably 50 nm or less, further preferably 45 nm or less, and particularly preferably 30 nm or less. Since the light-emitting element of the present invention has a narrow half-width of the emission spectrum, it is more preferably used for a top-emission type light-emitting element. In a top-emission type light-emitting element, due to the resonance effect brought about by the microcavity, the narrower the half-width, the higher the luminous efficiency. Therefore, high color purity and high luminous efficiency can be achieved concurrently.

[0099] The light-emitting element of the present invention is, for example, suitable for use in display device applications such as displays using a matrix method, a segmentation method, or a combination of the two methods. In addition, it is also preferably used for backlight applications of various devices and the like. Backlights are mainly used for the purpose of improving the visibility of display devices such as non-self-luminous displays, and are used in display devices such as liquid crystal displays, clocks, audio devices, automotive panels, display boards, and signs. In particular, for the backlights of liquid crystal displays and personal computer applications where thinning has been studied, the light-emitting element of the present invention is preferably used, and a thinner and lighter backlight can be provided compared to the prior art. In addition, the light-emitting element of the present invention is also preferably used as various lighting devices. High luminous efficiency and high color purity can be achieved concurrently. Furthermore, since it can be thinned and lightened, a lighting device with low power consumption, a vivid emission color, and high design can be realized.

[0100] The light-emitting element of the present invention has, for example, a structure including an anode and a cathode, and an organic layer between the anode and the cathode. It is preferably an organic electroluminescent element in which the organic layer at least includes a light-emitting layer that emits light through electric energy. The light-emitting element can be either a bottom-emission type or a top-emission type. The layer structure of the organic layer between the anode and the cathode in such a light-emitting element, in addition to the structure consisting of only a light-emitting layer, also includes the following laminated structures: 1) light-emitting layer / electron transport layer, 2) hole transport layer / light-emitting layer, 3) hole transport layer / light-emitting layer / electron transport layer, 4) hole injection layer / hole transport layer / light-emitting layer / electron transport layer, 5) hole transport layer / light-emitting layer / electron transport layer / electron injection layer, 6) hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer, 7) hole injection layer / hole transport layer / light-emitting layer / hole blocking layer / electron transport layer / electron injection layer, 8) hole injection layer / hole transport layer / electron blocking layer / light-emitting layer / hole blocking layer / electron transport layer / electron injection layer.

[0101] Furthermore, the above-described laminate may be a tandem light-emitting element formed by laminating multiple of the above-described laminates via an intermediate layer. As the intermediate layer, generally, an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, an intermediate insulating layer, etc. may be mentioned, and known materials may be used for formation. As a preferable specific example of the tandem light-emitting element, a laminate structure such as 9) hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / charge generation layer / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer may be mentioned. In addition, each of the above layers may be either a single layer or multiple layers, and may be doped. Furthermore, an element structure including a layer using a capping material for improving the light-emitting efficiency due to an optical interference effect may also be mentioned.

[0102] The electron transport layer is a layer that injects electrons from the cathode and further transports electrons. As the electron transport material used for the electron transport layer, a material having a large electron affinity, a large electron mobility, excellent stability, and being less likely to generate impurities that become traps is required. In addition, since the film quality of a low molecular weight compound is liable to deteriorate due to crystallization, a compound having a molecular weight of 400 or more is preferred. In the electron transport layer of the present invention, a hole blocking layer that can efficiently block the movement of holes is also included as a layer having the same meaning. The hole blocking layer and the electron transport layer may be formed individually or may be formed by laminating multiple materials. As the electron transport material, polycyclic aromatic derivatives, styryl-based aromatic ring derivatives, quinone derivatives, phosphorus oxide derivatives, various metal coordination compounds such as tris(8-hydroxyquinoline)aluminum(III) and other hydroxyquinoline coordination compounds, benzo-hydroxyquinoline coordination compounds, hydroxyazole coordination compounds, azomethine coordination compounds, tropolone metal coordination compounds, and flavonol metal coordination compounds may be mentioned.

[0103] In consideration of obtaining high-efficiency light emission by reducing the driving voltage, it is preferable to use a compound having a heteroaryl group containing an electron-withdrawing nitrogen. Here, the so-called electron-withdrawing nitrogen means a nitrogen atom that forms a multiple bond with an adjacent atom. Since a heteroaryl group containing an electron-withdrawing nitrogen has a large electron affinity, electrons are easily injected from the cathode, and lower voltage driving can be performed. In addition, more electrons are supplied to the light-emitting layer, and the recombination probability becomes higher, so the light-emitting efficiency is improved. As a compound having a heteroaryl group structure containing an electron-withdrawing nitrogen, for example, pyridine derivatives, triazine derivatives, pyrazine derivatives, pyrimidine derivatives, quinoline derivatives, quinoxaline derivatives, quinazoline derivatives, naphthyridine derivatives, benzoquinoline derivatives, phenanthroline derivatives, imidazole derivatives, azole derivatives, thiazole derivatives, triazole derivatives, diazole derivatives, thiadiazole derivatives, benzimidazole derivatives, benzo Compounds such as azole derivatives, benzothiazole derivatives, phenanthroimidazole derivatives, and oligopyridine derivatives such as bipyridine and terpyridine are preferred compounds.

[0104] Among them, from the viewpoint of electron transport ability, it is preferable to use imidazole derivatives such as tris(N-phenylbenzimidazol-2-yl)benzene, 1,3-bis[(4-tert-butylphenyl)-1,3,4- diazolyl]phenylene, etc. diazole derivatives; triazole derivatives such as N-naphthyl-2,5-diphenyl-1,3,4-triazole; phenanthroline derivatives such as bathocuproine (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), 1,3-bis(1,10-phenanthrolin-9-yl)benzene, etc.; benzoquinoline derivatives such as 2,2'-bis(benzo[h]quinolin-2-yl)-9,9'-spirobifluorene; bipyridine derivatives such as 2,5-bis(6'-(2',2”-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole; terpyridine derivatives such as 1,3-bis(4'-(2,2':6'2”-terpyridyl))benzene; naphthyridine derivatives such as bis(1-naphthyl)-4-(1,8-naphthyridin-2-yl)phenylphosphine oxide and triazine derivatives. In addition, if the electron transport material has a fused polycyclic aromatic skeleton, the glass transition temperature is increased, and the electron mobility is large and low voltage can be achieved, so it is more preferable.

[0105] As such a fused polycyclic aromatic skeleton, a fluoranthene skeleton, an anthracene skeleton, a pyrene skeleton, or a phenanthroline skeleton is preferred, and a fluoranthene skeleton or a phenanthroline skeleton is particularly preferred. The electron transport material can be used alone or two or more kinds can be used in combination. In addition, the electron transport layer may contain a donor material. Here, the donor material is a compound that improves the electron injection barrier, facilitates electron injection from the cathode or the electron injection layer to the electron transport layer, and further improves the conductivity of the electron transport layer. Preferred examples of the donor material include alkali metals such as lithium, inorganic salts containing alkali metals such as lithium fluoride, coordination compounds of alkali metals and organic compounds such as lithium hydroxyquinoline, alkaline earth metals, inorganic salts containing alkaline earth metals, coordination compounds of alkaline earth metals and organic compounds, rare earth metals such as europium and ytterbium, inorganic salts containing rare earth metals, coordination compounds of rare earth metals and organic compounds, etc. As the donor material, metallic lithium, rare earth metals, or lithium hydroxyquinoline (Liq) is particularly preferred.

[0106] The electron injection layer is formed for the purpose of assisting the injection of electrons from the cathode into the electron transport layer, and is composed of a compound having a heteroaromatic ring structure containing an electron-accepting nitrogen and the above-mentioned donor material. In addition, an inorganic insulator or semiconductor can also be used in the electron injection layer. By using these materials, short circuits of the light-emitting element can be prevented and the electron injection property can be improved, so they are preferred. As such an insulator, at least one metal compound selected from alkali metal chalcogenides, alkaline earth metal chalcogenides, alkali metal halides, and alkaline earth metal halides is preferably used.

[0107] The charge generation layer is a layer that generates or separates charges by applying a voltage and injects charges into an adjacent layer. The charge generation layer can be formed of a single layer or multiple layers can be stacked. Generally, a layer that easily generates electrons as charges is called an n-type charge generation layer, and a layer that easily generates holes is called a p-type charge generation layer. The charge generation layer is preferably composed of a bilayer, and more preferably a pn junction type charge generation layer composed of an n-type charge generation layer and a p-type charge generation layer. In the light-emitting element, the pn junction type charge generation layer generates charges or separates charges into holes and electrons by applying a voltage, and injects these holes and electrons into the light-emitting layer via the hole transport layer and the electron transport layer. Specifically, in a light-emitting element including a plurality of light-emitting layers, when a charge generation layer is used as an intermediate layer, the n-type charge generation layer supplies electrons to the first light-emitting layer existing on the anode side, and the p-type charge generation layer supplies holes to the second light-emitting layer existing on the cathode side.

[0108] Therefore, in a light-emitting element having two or more light-emitting layers, by having one or more charge generation layers between the light-emitting layers, the element efficiency can be further improved, the driving voltage can be reduced, and the durability of the element can be further improved. The n-type charge generation layer is composed of an n-type dopant and an n-type host, and conventional materials can be used for them. For example, as the n-type dopant, the donor materials exemplified as the materials for the electron transport layer are suitable. Among them, alkali metals or their salts, rare earth metals are preferred, and materials selected from metallic lithium, lithium fluoride (LiF), lithium hydroxyquinoline (Liq), and ytterbium metal are more preferred. In addition, as the n-type host, the substances exemplified as the electron transport materials are suitable. Among them, materials selected from triazine derivatives, phenanthroline derivatives, and oligopyridine derivatives are preferred, and phenanthroline derivatives or terpyridine derivatives are more preferred.

[0109] The above-mentioned p-type charge generation layer is composed of a p-type dopant and a p-type host, and conventional materials can be used for them. For example, as the p-type dopant, acceptor materials, iodine, FeCl 3 , FeF 3 , SbCl 5etc. Specifically, examples include HAT-CN6, F4-TCNQ, tetracyanoquinodimethane derivatives, [n]cumulene derivatives, iodine, FeCl 3 , FeF 3 , SbCl 5 etc. Among them, HAT-CN6, (2E,2’E,2”E)-2,2’,2”-(cyclopropane-1,2,3-triylidene)tris(2-(perfluorophenyl)acetonitrile), (2E,2’E,2”E)-2,2’,2”-(cyclopropane-1,2,3-triylidene)tris(2-(4-cyanoperfluorophenyl)acetonitrile) and other [n]cumulene derivatives are more preferable. A thin film of a p-type dopant can be formed, and its film thickness is preferably 10 nm or less. In addition, as the p-type host, an arylamine derivative is preferred.

[0110] The crystals of the phenanthroline derivative of the present invention can be used for the electron transport layer, electron injection layer, and charge generation layer. When used for the electron transport layer, for example, it is suitable to use it in a vapor deposition film with a thickness of several tens of nm formed by laminating a host material, a doping material, and a TADF material. The light-emitting element fabricated by such an operation shows a very high external quantum efficiency.

[0111] In addition, when the crystals of the phenanthroline derivative of the present invention are used for the electron injection layer, for example, it is suitable to use it in a co-evaporation film with a thickness of several nm containing an alkali metal as a donor material, and the above-mentioned light-emitting layer and electron transport layer are sequentially laminated, and it is preferably laminated on the electron transport layer. The light-emitting element fabricated by such an operation also shows a very high external quantum efficiency.

[0112] In addition, when the crystals of the phenanthroline derivative of the present invention are used for the charge generation layer, for example, it is suitable to use it in the n-type host material of the n-type charge generation layer of a tandem-type fluorescent light-emitting element containing an alkali metal as an n-type dopant, and the above-mentioned light-emitting layer and electron transport layer are sequentially laminated, and it is preferably laminated on the electron transport layer. The light-emitting element fabricated by such an operation also shows a very high external quantum efficiency.

[0113] The anode is an electrode formed on the substrate, and there is no particular limitation as long as it is a material that can inject holes into the organic layer well. For a bottom-emitting type element, a transparent or semi-transparent electrode is preferred, and for a top-emitting type element, a reflective electrode is preferred. Examples of the material for the transparent or semi-transparent electrode include conductive metal oxides such as zinc oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO); or metals such as gold, silver, aluminum, chromium; and conductive polymers such as polythiophene, polypyrrole, and polyaniline. However, in order to make the light semi-transmissive when using a metal, it is preferable to make the film thickness thin.

[0114] Among these, from the viewpoints of transparency and stability, indium tin oxide (ITO) is more preferable. As the material for the reflective electrode, a material that has no absorption of all light and has a high reflectivity is preferable. Specifically, examples thereof include metals such as aluminum, silver, and platinum. The method for forming the anode can be the optimal method according to its forming material, and sputtering method, evaporation method, inkjet method, etc. can be cited. For example, the sputtering method is used when forming the anode with a metal oxide, and the evaporation method is used when forming the anode with a metal. The film thickness of the anode is not particularly limited, but is preferably several nm to several hundred nm. In addition, these electrode materials can be used alone, or multiple materials can be laminated or mixed and used. Further, various wirings, circuits, and switching elements can be interposed between the substrate and the anode.

[0115] The cathode is an electrode formed on the surface on the opposite side of the anode with the organic layer interposed therebetween, and is particularly preferably formed on the electron transport layer or the electron injection layer. The material used for the cathode is not particularly limited as long as it is a material that can inject electrons into the light-emitting layer with good electron efficiency. However, for a bottom-emission type element, a reflective electrode is preferable, and for a top-emission type element, a semi-transparent electrode is preferable.

[0116] As the material for the cathode, generally, metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium; alloys of these metals with low work function metals such as lithium, sodium, potassium, calcium, and magnesium; or conductive metal oxides such as zinc oxide, indium tin oxide (ITO), and indium zinc oxide (IZO) are preferable. Among them, the metal selected from aluminum, silver, and magnesium as the main component is preferable in terms of resistance value, film formation ease, film stability, luminous efficiency, etc.

[0117] In addition, if the cathode is composed of magnesium and silver, the electron injection into the electron transport layer and the electron injection layer in the present invention becomes easy, and low-voltage driving can be performed, so it is preferable. Further, in order to protect the cathode, a protective layer (cap layer) can be laminated on the cathode. The material constituting the protective layer is not particularly limited, and examples thereof include metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium; alloys using these metals; inorganic substances such as silicon dioxide, titanium dioxide, and silicon nitride; and organic polymer compounds such as polyvinyl alcohol, polyvinyl chloride, and hydrocarbon-based polymer compounds. However, in the case where the light-emitting element has an element structure (top-emission structure) that emits light from the cathode side, the material used for the protective layer is selected from materials having light transmissibility in the visible light region.

[0118] The light-emitting layer is a layer that emits light by utilizing the excitation energy generated by the recombination of holes and electrons. The light-emitting layer may be composed of a single material, but from the viewpoints of color purity and light-emitting intensity, it is preferably composed of two or more materials, namely a host compound (hereinafter sometimes referred to as "the first compound") and a dopant compound (hereinafter sometimes referred to as "the second compound"). As the first compound, as a thermally activated delayed fluorescence material, a thermally activated delayed fluorescent compound can be cited as a suitable example. A thermally activated delayed fluorescent compound is generally also referred to as a TADF material, which is a material that promotes reverse intersystem crossing from the triplet excited state to the singlet excited state by making the energy gap between the singlet excited state energy level and the triplet excited state energy level small, thereby increasing the generation probability of singlet excitons. The difference between the lowest excited singlet state energy level and the lowest excited triplet state energy level (denoted as ΔEST) in the TADF material is preferably 0.3 eV or less. By utilizing the delayed fluorescence obtained from this thermally activated delayed fluorescence mechanism, the theoretical internal efficiency can be increased to 100%.

[0119] Furthermore, in the case where Forster-type energy transfer occurs from the singlet exciton of the first compound having thermally activated delayed fluorescence to the singlet exciton of the second compound, fluorescence emission from the singlet exciton of the second compound is observed. In order for such energy transfer to occur, it is preferable that the lowest excited singlet state energy level of the first compound is higher than the lowest excited singlet state energy level of the second compound. Here, when the second compound is a fluorescent material having a sharp emission spectrum, a light-emitting device with high efficiency and high color purity can be obtained. Thus, if the light-emitting layer contains a thermally activated delayed fluorescent compound, high-efficiency light emission can be achieved, contributing to power consumption reduction of the display. The thermally activated delayed fluorescent compound may be a compound that exhibits thermally activated delayed fluorescence with a single material, or may be a compound that exhibits thermally activated delayed fluorescence with multiple compounds as in the case of forming an exciplex coordination compound.

[0120] As the thermally activated delayed fluorescent compound, a single compound or a mixture of multiple compounds can be used, and known materials can be used. Specifically, for example, benzonitrile derivatives, triazine derivatives, disulfoxide derivatives, carbazole derivatives, indolocarbazole derivatives, dihydrophenazine derivatives, thiazole derivatives, diazole derivatives, etc. are cited. Particularly preferred are compounds having an electron-donating moiety (donor moiety) and an electron-withdrawing moiety (acceptor moiety) within the same molecule.

[0121] In addition, the light-emitting layer of the above-described light-emitting element may contain a methylene pyrrole boron coordination compound represented by the following general formula (2). In particular, when the above-described first compound is a thermally activated delayed fluorescence compound, it is preferable that the above-described second compound is a methylene pyrrole boron coordination compound. When used as a dopant, the methylene pyrrole boron coordination compound is a useful light-emitting material that can obtain a sharp emission spectrum. However, it is difficult to realize a light-emitting element that maintains a sharp emission spectrum while having high luminous efficiency and high durability. However, the methylene pyrrole boron coordination compound represented by the following general formula (2) can provide a light-emitting material with a high fluorescence quantum yield and a sharp emission spectrum, and a light-emitting element with high luminous efficiency, color purity, and durability.

[0122]

[0123] Here, in the above general formula (2), X 1 is a nitrogen atom or a carbon atom, and in the case of this carbon atom, one atom or monovalent group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted heteroaryl group, a halogen atom, a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted amino group, a nitro group, a cyano group, a substituted or unsubstituted silyl group, and a substituted or unsubstituted siloxy group is bonded.

[0124] R 1 ~R 6 are each independently an atom or group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, an alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted heteroaryl group, a halogen atom, a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted amino group, a nitro group, a cyano group, a substituted or unsubstituted silyl group, and a substituted or unsubstituted siloxy group. Among them, in the R 1 and R 2 group, the R 2 and R 3 group, the R 4 and R 5 group, the R 5 and R 6 group, in any one or more of these groups, a bond may be formed between the groups constituting the group to form a ring. Z 1 and Z 2Each independently is an atom or group selected from a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a cyano group, and a substituted or unsubstituted aryloxy group, wherein a bond can be formed between Z 1 and Z 2 to form a ring.

[0125] In all of the above groups, hydrogen may be deuterium. The same applies to the compounds or partial structures described below.

[0126] In addition, in all of the above groups, as the substituent in the case of being substituted, it is preferably a group selected from an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an aralkyl group, a halogen, a cyano group, a formyl group, an acyl group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxysulfonyl group, an aminosulfonyl group, an amino group, a nitro group, a silyl group, a siloxy group, a boranyl group, a phosphinyl group, and an oxo group. Further, more preferably, it is a specific substituent preferred in the description of each substituent described below. In addition, these substituents may be further substituted by the above substituents.

[0127] In the description of this specification, the so-called "unsubstituted" means that the atom bonded to the basic skeleton or group to be the object is only a hydrogen atom or a deuterium atom. In the compounds or partial structures described below, the same applies to the case of "substituted or unsubstituted".

[0128] The term "alkyl group" means, for example, saturated aliphatic hydrocarbon groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, etc., which may be substituted or unsubstituted. There is no particular limitation on the additional substituent in the case of being substituted, and examples thereof include an alkyl group, a halogen, an aryl group, a heteroaryl group, etc., which is also common in the following descriptions. The number of carbon atoms of the alkyl group is not particularly limited, but from the viewpoints of availability and cost, it is preferably in the range of 1 or more and 20 or less, more preferably in the range of 1 or more and 8 or less.

[0129] The term "cycloalkyl group" means, for example, saturated alicyclic hydrocarbon groups such as cyclopropyl, cyclohexyl, norbornyl, adamantyl, etc., which may be substituted or unsubstituted. The number of carbon atoms of the alkyl moiety is not particularly limited, but it is preferably in the range of 3 or more and 20 or less.

[0130] The term "heterocyclic group" means, for example, aliphatic rings having atoms other than carbon in the ring such as a pyran ring, a piperidine ring, a cyclic amide, etc., which may be substituted or unsubstituted. The number of carbon atoms of the heterocyclic group is not particularly limited, but it is preferably in the range of 2 or more and 20 or less.

[0131] The so-called alkenyl group means, for example, an unsaturated aliphatic hydrocarbon group containing a double bond such as vinyl, allyl, butadienyl, etc., which may be substituted or unsubstituted. The number of carbon atoms in the alkenyl group is not particularly limited, but is preferably in the range of 2 or more and 20 or less.

[0132] The so-called cycloalkenyl group means, for example, an unsaturated alicyclic hydrocarbon group containing a double bond such as cyclopentenyl, cyclopentadienyl, cyclohexenyl, etc., which may be substituted or unsubstituted. The number of carbon atoms in the cycloalkenyl group is not particularly limited, but is preferably in the range of 3 or more and 20 or less.

[0133] The so-called alkynyl group means, for example, an unsaturated aliphatic hydrocarbon group containing a triple bond such as ethynyl, etc., which may be substituted or unsubstituted. The number of carbon atoms in the alkynyl group is not particularly limited, but is preferably in the range of 2 or more and 20 or less.

[0134] The so-called alkoxy group means, for example, a functional group in which an aliphatic hydrocarbon group is bonded via an ether bond such as methoxy, ethoxy, propoxy, etc., and the aliphatic hydrocarbon group may be substituted or unsubstituted. The number of carbon atoms in the alkoxy group is not particularly limited, but is preferably in the range of 1 or more and 20 or less.

[0135] The so-called alkylthio group is a group in which the oxygen atom of the ether bond of the alkoxy group is replaced by a sulfur atom. The hydrocarbon group of the alkylthio group may be substituted or unsubstituted. The number of carbon atoms in the alkylthio group is not particularly limited, but is preferably in the range of 1 or more and 20 or less.

[0136] The so-called aryloxy group means, for example, a functional group in which an aromatic hydrocarbon group is bonded via an ether bond such as phenoxy, etc., and the aromatic hydrocarbon group may be substituted or unsubstituted. The number of carbon atoms in the aryloxy group is not particularly limited, but is preferably in the range of 6 or more and 40 or less.

[0137] The so-called arylthio group is a group in which the oxygen atom of the ether bond of the aryloxy group is replaced by a sulfur atom. The aromatic hydrocarbon group in the arylthio group may be substituted or unsubstituted. The number of carbon atoms in the arylthio group is not particularly limited, but is preferably in the range of 6 or more and 40 or less.

[0138] The so-called aralkyl group is, for example, an alkyl group in which one hydrogen atom of an alkyl group such as phenylmethyl, phenylethyl, etc. is substituted by an aryl group. The number of carbon atoms in the aralkyl group is not particularly limited, but is preferably in the range of 6 or more and 40 or less.

[0139] The aryl group can be either a monocyclic or a fused ring, and means, for example, phenyl, naphthyl, fluorenyl, benzofluorenyl, dibenzofluorenyl, phenanthryl, anthryl, benzophenanthryl, benzanthryl, Aryl groups such as phenyl, pyrenyl, fluoranthenyl, benzo[9,10]phenanthryl, benzo[a]fluoranthenyl, dibenzoanthryl, perylenyl, and helicenyl. Among them, groups selected from phenyl, biphenyl, terphenyl, naphthyl, fluorenyl, phenanthryl, anthryl, pyrenyl, fluoranthenyl, and benzo[9,10]phenanthryl are preferred. The aryl group may be substituted or unsubstituted. In the present invention, groups in which multiple phenyl groups such as biphenyl and terphenyl are bonded via a single bond are treated as phenyl groups having an aryl group as a substituent. The number of carbon atoms of the aryl group is not particularly limited, but is preferably 6 or more and 40 or less, more preferably 6 or more and 30 or less. In addition, in the case of a phenyl group having substituents on two adjacent carbon atoms in the phenyl group, a ring structure may be formed between these substituents.

[0140] The heteroaryl group may be either a monocyclic or a fused-ring group, and represents, for example, pyridyl, furyl, phenylthio, quinolinyl, isoquinolinyl, pyrazinyl, pyrimidinyl, pyridazinyl, triazinyl, phthalazinyl, cinnolinyl, phthalazinyl, quinoxalinyl, quinazolinyl, benzofuryl, benzothiophenyl, indolyl, dibenzofuryl, dibenzothiophenyl, carbazolyl, benzocarbazolyl, carbolinyl, indolocarbazolyl, benzofurocarbazolyl, benzothienocarbazolyl, indeno[1,2-c]carbazolyl, benzoquinolinyl, acridinyl, dibenzoacridinyl, benzimidazolyl, imidazopyridyl, benzo oxazolyl, benzothiazolyl, phenanthrolinyl, etc., which are cyclic aromatic groups having atoms other than carbon and hydrogen, i.e., heteroatoms, in one or more rings. As the heteroatom, a nitrogen atom, an oxygen atom, or a sulfur atom is preferred. The heteroaryl group may be substituted or unsubstituted. The number of carbon atoms of the heteroaryl group is not particularly limited, but is preferably 2 or more and 40 or less, more preferably 2 or more and 30 or less.

[0141] The so-called halogen represents an atom selected from fluorine, chlorine, bromine, and iodine.

[0142] The so-called cyano group is a functional group represented by -CN. Here, the carbon atom is bonded to other groups.

[0143] The so-called formyl group is a functional group represented by -C(=O)H. Here, the carbon atom is bonded to other groups.

[0144] The so-called acyl group represents a functional group in which an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heteroaryl group is bonded via a carbonyl group, such as acetyl, propionyl, benzoyl, acryloyl, etc. These substituents may be further substituted. The number of carbon atoms of the acyl group is not particularly limited, but is preferably 2 or more and 40 or less, more preferably 2 or more and 30 or less.

[0145] The so-called alkoxycarbonyl group means, for example, a functional group obtained by bonding an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, etc. via an ester bond. These substituents may be further substituted. The number of carbon atoms of the alkoxycarbonyl group is not particularly limited, but is preferably in the range of 1 or more and 20 or less. More specifically, examples include methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, isopropoxymethoxycarbonyl, hexyloxycarbonyl, phenoxycarbonyl, etc.

[0146] The so-called carbamoyl group means, for example, a functional group obtained by bonding an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, etc. via an amide bond. These substituents may be further substituted. The number of carbon atoms of the carbamoyl group is not particularly limited, but is preferably in the range of 1 or more and 20 or less. More specifically, examples include methylcarbamoyl, ethylcarbamoyl, propylcarbamoyl, butylcarbamoyl, isopropylcarbamoyl, hexylcarbamoyl, phenylcarbamoyl, etc.

[0147] The so-called alkylsulfonyl group and arylsulfonyl group mean, for example, a functional group obtained by bonding an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, etc. via an -S(=O) 2 - bond. These substituents may be further substituted. The number of carbon atoms of the alkylsulfonyl group and arylsulfonyl group is not particularly limited, but is preferably in the range of 1 or more and 20 or less.

[0148] The so-called alkoxysulfonyl group means, for example, a functional group obtained by bonding an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, etc. via a sulfonate ester bond. Here, the so-called sulfonate ester bond means that the carbonyl part of the ester bond, i.e., -C(=O)-, is replaced by a sulfonyl part, i.e., -S(=O) 2 - bond. In addition, these substituents may be further substituted. The number of carbon atoms of the alkoxysulfonyl group is not particularly limited, but is preferably in the range of 1 or more and 20 or less.

[0149] The so-called aminosulfonyl group means, for example, a functional group obtained by bonding an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, etc. via a sulfonamide bond. Here, the so-called sulfonamide bond means that the carbonyl part of the ester bond, i.e., -C(=O)-, is replaced by a sulfonyl part, i.e., -S(=O) 2 - bond. In addition, these substituents may be further substituted. The number of carbon atoms of the aminosulfonyl group is not particularly limited, but is preferably in the range of 1 or more and 20 or less.

[0150] The so-called amino group is a substituted or unsubstituted amino group. As substituents in the case of substitution, examples include, for example, an aryl group, a heteroaryl group, a linear alkyl group, and a branched alkyl group. As the aryl group and heteroaryl group, phenyl, naphthyl, pyridyl, and quinolinyl are preferred. These substituents may be further substituted. The number of carbon atoms is not particularly limited, but is preferably in the range of 2 or more and 50 or less, more preferably in the range of 6 or more and 40 or less, and particularly preferably in the range of 6 or more and 30 or less.

[0151] The term "silyl group" refers to a functional group formed by the bonding of substituted or unsubstituted silicon atoms, and examples thereof include alkylsilyl groups such as trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, propyldimethylsilyl, vinyldimethylsilyl, etc., and arylsilyl groups such as phenyldimethylsilyl, tert-butyldiphenylsilyl, triphenylsilyl, trinaphthylsilyl, etc. The substituents on the silicon can be further substituted. The number of carbon atoms in the silyl group is not particularly limited, but is preferably in the range of 1 or more and 30 or less.

[0152] The term "siloxanyl group" refers to a silicon compound group such as trimethylsiloxanyl group via an ether bond. The substituents on the silicon can be further substituted.

[0153] The term "boranyl group" refers to a substituted or unsubstituted boranyl group. Examples of the substituents in the case of substitution include aryl, heteroaryl, linear alkyl, branched alkyl, aryl ether group, alkoxy group, and hydroxyl group, and among them, aryl and aryl ether group are preferred.

[0154] The term "phosphoryl group" refers to a group represented by -P(=O)R 16 R 17 shown group. R 16 and R 17 each independently selected from the same group as R 1 ~R 6 same group.

[0155] In the descriptions of the above respective groups, the scope of the substituents capable of substitution in the case of substitution in the descriptions of "may be substituted or unsubstituted" and "the substituents can be further substituted" is, in comparison with the compound before substitution, the scope of substituents that are evaluated as chemically equivalent or have almost no influence on the performance when used in a light-emitting element. From another perspective, from the viewpoint of being used in a light-emitting element, it means including the scope that can be evaluated as an equivalent. In addition, the descriptions of the respective groups in the following general formula (3) and general formula (4) refer to the descriptions of the above respective groups, and in addition, regarding the descriptions of R 7 ~R 15 and Ar 1 the scope of the substituents in the description of "substituted or unsubstituted" in the description is also the same meaning as the scope of the substituents capable of substitution in the case of substitution in the descriptions of "may be substituted or unsubstituted" and "the substituents can be further substituted" above.

[0156] Methylene pyrrole boron coordination compounds exhibit high fluorescence quantum yields due to their strong and highly planar skeletons. In addition, due to the small full width at half maximum of the emission spectrum, efficient emission and high color purity can be achieved in light-emitting elements. To further improve the luminous efficiency, it is effective to suppress the rotation / vibration of the substituents of the methylene pyrrole boron coordination compound, reduce the energy loss, and increase the fluorescence quantum yield. In addition, to improve the color purity, it is effective to reduce the vibrational relaxation in the excited state of the methylene pyrrole boron coordination compound and decrease the full width at half maximum of the emission spectrum. From this perspective, it is preferable to use a substance in which, in the structure represented by the above general formula (2), X 1 is a carbon atom and is bonded to the above atom or monovalent group.

[0157] By using a substance in which X 1 is a carbon atom and one of the above atoms or monovalent groups is bonded to this carbon atom, a methylene pyrrole boron coordination compound with a high fluorescence quantum yield and a small full width at half maximum can be provided. Further, if the intramolecular rotation of the methylene pyrrole skeleton by the group bonded to the bridgehead position is suppressed, energy deactivation can be suppressed, which is beneficial to improving the luminous efficiency. In addition, the stability of the methylene pyrrole boron coordination compound affects the durability of the light-emitting element. To further improve its stability, it is preferable to introduce a bulky substituent at the bridgehead position. By introducing a bulky substituent, the methylene pyrrole skeleton can be protected from the influence of interactions with other surrounding molecules.

[0158] As a particularly preferred monovalent group bonded to the carbon atom in the case where X 1 is a carbon atom, the groups represented by the following general formula (3) and general formula (4) are preferred from the viewpoint of suppressing energy deactivation.

[0159]

[0160] (Here, R 9 to R 11 are each independently selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a hydroxyl group, a mercapto group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a halogen atom, a cyano group, a formyl group, an acyl group, a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted alkylsulfonyl group, a substituted or unsubstituted arylsulfonyl group, a substituted or unsubstituted sulfamoyl group, a substituted or unsubstituted amino group, a nitro group, a substituted or unsubstituted silyl group, and an atom or group in a ring structure formed with an adjacent group,

[0161] R 7 and R 8 each independently represents a group selected from substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl.

[0162]

[0163] (Here, R 12 to R 14 each independently represents an atom or group selected from a hydrogen atom, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclic group, substituted or unsubstituted alkenyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted alkynyl, hydroxy group, mercapto group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, halogen atom, cyano group, formyl group, acyl group, carboxyl group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted alkylsulfonyl group, substituted or unsubstituted arylsulfonyl group, substituted or unsubstituted alkoxysulfonyl group, substituted or unsubstituted aminosulfonyl group, substituted or unsubstituted amino group, nitro group, substituted or unsubstituted silyl group, substituted or unsubstituted siloxy group, substituted or unsubstituted boranyl group, and substituted or unsubstituted phosphinyl group.

[0164] R 15 represents a group selected from substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclic group, substituted or unsubstituted alkenyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted alkynyl, hydroxy group, mercapto group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, halogen atom, cyano group, formyl group, acyl group, carboxyl group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted alkylsulfonyl group, substituted or unsubstituted arylsulfonyl group, substituted or unsubstituted alkoxysulfonyl group, substituted or unsubstituted aminosulfonyl group, substituted or unsubstituted amino group, nitro group, substituted or unsubstituted silyl group, substituted or unsubstituted siloxy group, substituted or unsubstituted boranyl group, and substituted or unsubstituted phosphinyl group.

[0165] Ar 1 represents a group selected from substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl.

[0166] In addition, in the case of a compound containing a group represented by the general formula (3), in the methylene pyrrole boron compound represented by the general formula (2), Z 1 and Z 2Each independently represents a group selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, substituted or unsubstituted aryl, halogen atom, and cyano group, R 1 、R 3 、R 4 and R 6 each independently represents substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl (here, these aryl and heteroaryl groups can be monocyclic or fused-ring. Among them, when one or both of R 1 and R 6 are monocyclic aryl and heteroaryl groups, the monocyclic aryl and heteroaryl groups have one or more secondary alkyl groups, one or more tertiary alkyl groups, one or more aryl groups or one or more heteroaryl groups as substituents, or have two or more methyl groups and primary alkyl groups in total as substituents.). R 2 and R 5 are preferably each independently selected from a hydrogen atom, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylthio, substituted or unsubstituted aryloxy, substituted or unsubstituted arylthio, halogen atom, cyano group, carboxyl group, substituted or unsubstituted alkoxycarbonyl, substituted or unsubstituted carbamoyl, substituted or unsubstituted amino, nitro group, and substituted or unsubstituted silyl. Among them, in this case, one or both of the groups between R 4 and R 5 , and between R 2 and R 3 can form a bond via one or two atoms between the above groups.

[0167] In addition, the more carbon atoms in the above primary alkyl, secondary alkyl, and tertiary alkyl groups, the more the steric hindrance increases, so it is preferred. However, from the viewpoint of the ease of synthesis of the compound, it is preferably about 2 to 10, more preferably 4 to 10.

[0168] Furthermore, from the viewpoints of luminescence characteristics and thermal stability, Z 1 and Z 2 are preferably alkyl, alkoxy, aryl ether group, halogen, or cyano group. In addition, from the viewpoints of stabilizing the excited state to obtain a higher fluorescence quantum yield and improving durability, Z 1 and Z 2 are more preferably electron-withdrawing groups. Specifically, they are more preferably fluorine atom, fluorinated alkyl, fluorinated alkoxy, fluorinated aryl ether group, or cyano group, further preferably fluorine atom or cyano group, and most preferably fluorine atom.

[0169] R 1 and R6 Groups that contribute to the stability and luminescence efficiency of the methylene pyrrole boron coordination compound. By stability is meant electrical stability and thermal stability. Electrical stability means that the compound is not easily deteriorated, such as decomposition, in a state where it is continuously energized with a light-emitting element. Thermal stability means that the compound is not easily deteriorated by heating processes such as sublimation purification and evaporation during manufacturing, or by the ambient temperature around the light-emitting element. If the compound deteriorates, the luminescence efficiency decreases, so the stability of the compound is important for improving the durability of the light-emitting element. From the viewpoints of the stability and luminescence efficiency of the compound, R 1 and R 6 are preferably substituted or unsubstituted aryl groups. In order to prevent aggregation of the methylene pyrrole boron coordination compounds with each other and avoid concentration quenching, R 1 and R 6 are preferably groups with large steric hindrance among the above groups. From this viewpoint, R 1 and R 6 are preferably selected from phenyl groups having one or more tertiary alkyl groups as substituents, phenyl groups having one or more aryl groups as substituents, phenyl groups having one or more heteroaryl groups as substituents, phenyl groups having a total of two or more methyl groups and primary alkyl groups as substituents and at least one of them being substituted at the 2-position relative to the binding site to the pyrrole ring, and fused polycyclic aromatic hydrocarbon groups. In addition, the smaller the degree of freedom of rotation or vibration, the more the efficiency reduction due to thermal deactivation can be suppressed. Therefore, R 1 and R 6 are preferably functional groups having a rigid structure or a highly symmetric structure. From this viewpoint, R 1 and R 6 are more preferably any one of phenyl groups having one or more tertiary butyl groups as substituents, phenyl groups having one or more phenyl groups as substituents, phenyl groups substituted with methyl groups at least at the 2-position and 6-position relative to the binding site to the pyrrole ring, and phenyl groups having substituents symmetrically with respect to the binding axis to the pyrrole, or unsubstituted fused polycyclic aromatic hydrocarbon groups. Further from the viewpoint of ease of manufacture, they are more preferably 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 4-tert-butylphenyl, 3,5-di-tert-butylphenyl, 4-biphenyl, or 1-naphthyl.

[0170] R 3 and R 4 are groups that contribute to the control of the emission wavelength. When the methylene pyrrole boron coordination compound emits red light, there is a method of extending the conjugation and shifting the emission wavelength to a longer wavelength by directly bonding an aryl group or a heteroaryl group to the methylene pyrrole metal coordination compound skeleton. For this reason, R 3 and R 4is a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. However, from the viewpoint of the stability of the compound, a substituted or unsubstituted aryl group is more preferred.

[0171] R 2 and R 5 mainly affect the peak wavelength, the half-width of the emission spectrum, stability, or crystallinity. From the viewpoints of narrowing the half-width of the emission spectrum, the stability that affects the durability of the device, and the ease of manufacturing including recrystallization purification, it is preferred that at least one of 2 and R 5 is a hydrogen atom, or a substituted or unsubstituted alkyl group, and more preferably both are.

[0172] In addition, in the compound represented by the general formula (2), in the group of R 1 and R 2 group, the group of R 2 and R 3 group, the group of R 4 and R 5 group, the group of R 5 and R 6 group, in any one or more groups, a bond can be formed between the groups constituting the group to form a ring. In addition, a bond can also be formed between Z 1 and Z 2 to form a ring. However, in this sense, it means that in R 1 ~R 6 , as a condensed ring with the methylene pyrrole ring, preferably a condensed ring, that is, a ring that can form a five-membered ring to a seven-membered ring by including two carbons of the methylene pyrrole ring. In addition, in Z 1 and Z 2 , it can include a heterocyclic ring containing boron as a partial structure.

[0173] In addition, in order to improve the luminescence efficiency, it is effective to suppress the rotation / vibration of the group represented by the general formula (3) to reduce the energy loss and increase the fluorescence quantum yield. In order to suppress the rotation / vibration of the group represented by the general formula (3), R 7 and R 8 are selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. It is preferred that at least one of them is a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group. On the other hand, from the viewpoint of the ease of manufacturing, it is preferred that one of R 7 and R 8 is a substituted or unsubstituted alkyl group, and more preferably a methyl group. In addition, R 9 ~R 11 are used for adjusting the peak wavelength, crystallinity, sublimation temperature, etc. What particularly affects the peak wavelength is the substituent at the 4-position relative to the bond with the methylene pyrrole skeleton, that is, R 10。If R 10 is an electron-donating group, the emission peak wavelength shifts to the shorter wavelength side. As the electron-donating group, specifically, examples include methyl, ethyl, tert-butyl, cyclohexyl, methoxy, ethoxy, phenyl, tolyl, naphthyl, furyl, dibenzofuryl, etc. Especially when R 10 is an alkoxy group such as methoxy or ethoxy with strong electron-donating property, the short wavelength shift is large and it is useful for wavelength adjustment. On the other hand, if R 10 is an electron-withdrawing group, the emission peak shifts to the longer wavelength side. As the electron-withdrawing group, specifically, examples include fluorine atom, trifluoromethyl, cyano, pyridyl, pyrimidinyl, etc. Especially when R 10 is a group selected from a fluorine atom, trifluoromethyl and cyano with strong electron-withdrawing property, the long wavelength shift is large and it is useful for wavelength adjustment. However, the electron-donating group and the electron-withdrawing group are not limited thereto.

[0174] In addition, in the case of including the group represented by the general formula (4), in the methylene pyrrole boron compound represented by the general formula (2), Z 1 and Z 2 are each independently an atom or group selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aryl group, a halogen atom, and a cyano group, and R 1 to R 6 are each independently a group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted amino group, a substituted or unsubstituted silyl group, and a substituted or unsubstituted siloxy group, wherein it is desirable that at least one of R 1 , R 3 , R 4 , R 6 is a hydrogen atom or a substituted or unsubstituted alkyl group.

[0175] Furthermore, from the viewpoints of emission characteristics and thermal stability, Z 1 and Z 2 are preferably an alkyl group, an alkoxy group, an aryl ether group, a halogen or a cyano group. In addition, from the viewpoints of stabilizing the excited state to obtain a higher fluorescence quantum yield and improving durability, Z 1 and Z 2 are more preferably an electron-withdrawing group, specifically, more preferably a fluorine atom, a fluorinated alkyl group, a fluorinated alkoxy group, a fluorinated aryl ether group or a cyano group, further preferably a fluorine atom or a cyano group, and most preferably a fluorine atom.

[0176] R 1and R 6 affect the emission peak wavelength, crystallinity, sublimation temperature, etc. of the methylene pyrrole boron coordination compound. From the viewpoint of making the half-width of the emission spectrum smaller, R 1 and R 6 are preferably a hydrogen atom or an alkyl group. Further, from the viewpoint of further improving the fluorescence quantum yield, R 1 and R 6 are more preferably an alkyl group, and from the viewpoint of ease of production, they are further preferably a methyl group.

[0177] R 3 and R 4 mainly affect the emission peak wavelength, half-width of the emission spectrum, stability, or crystallinity of the methylene pyrrole boron coordination compound. From the viewpoints of making the half-width of the emission spectrum smaller, making the stability higher, and ease of synthesis including recrystallization formation, it is preferred that at least one of R 3 and R 4 , preferably both, are groups selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. Further, from the viewpoint of further reducing the half-width, R 3 and R 4 are more preferably an alkyl group, and from the viewpoint of ease of production, they are further preferably a methyl group.

[0178] R 2 and R 5 mainly affect the emission peak wavelength, half-width of the emission spectrum, stability, or crystallinity of the methylene pyrrole boron coordination compound. From the viewpoints of making the half-width of the emission spectrum smaller, further improving the stability, and ease of synthesis including recrystallization purification, it is preferred that at least one of R 2 and R 5 , preferably both, are a hydrogen atom, a substituted or unsubstituted alkyl group, and from the viewpoint of ease of production, they are further preferably both hydrogen atoms.

[0179] In addition, in order to improve the luminescence efficiency, it is effective to suppress the rotation / vibration of the group represented by the general formula (4) and reduce the energy loss to increase the fluorescence quantum yield. In order to suppress the rotation / vibration of the group represented by the general formula (4), R 11 and Ar 1 are more preferably a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, and from the viewpoint of ease of production, they are further preferably a phenyl group, 2,6-dimethylphenyl group, 2,4,6-trimethylphenyl group, 4-tert-butylphenyl group, 3,5-di-tert-butylphenyl group, 4-methoxyphenyl group, 4-biphenyl group, or 1-naphthyl group.

[0180] When introducing an aryl group or a heteroaryl group into the methylene pyrrole skeleton, for example, a method of forming a carbon-carbon bond by a coupling reaction of a halogenated derivative of a methylene pyrrole boron coordination compound with a boric acid or a borate derivative in the presence of a metal catalyst such as palladium can be mentioned, but it is not limited thereto. Similarly, when introducing an amino group or a carbazolyl group into the methylene pyrrole skeleton, for example, a method of forming a carbon-nitrogen bond by a coupling reaction of a halogenated derivative of a methylene pyrrole boron coordination compound with an amine or a carbazole derivative in the presence of a metal catalyst such as palladium can be mentioned, but it is not limited thereto.

[0181] The obtained methylene pyrrole boron coordination compound is preferably purified by organic synthesis such as recrystallization and column chromatography, and then further purified by heating under reduced pressure, which is generally called sublimation purification, to remove low-boiling components and improve the purity. The heating temperature in sublimation purification is not particularly limited, but from the viewpoint of preventing thermal decomposition of the methylene pyrrole boron coordination compound, it is preferably 330 °C or lower, more preferably 300 °C or lower. From the viewpoint that the light-emitting element can exhibit stable characteristics, the purity of the methylene pyrrole boron coordination compound produced by such an operation is preferably 99% by weight or more.

[0182] The optical properties of the methylene pyrrole boron coordination compound are obtained by measuring the absorption spectrum and the emission spectrum of a diluted solution. As the solvent, as long as it is a transparent solvent that dissolves the methylene pyrrole boron coordination compound and the absorption spectrum of the solvent does not overlap with the absorption spectrum of the methylene pyrrole boron coordination compound, it is not particularly limited. Specifically, toluene etc. can be exemplified. The concentration of the solution is not particularly limited as long as it has sufficient absorbance and is in a concentration range where concentration quenching does not occur, but it is preferably in the range of 1×10 -4 mol / L to 1×10 -7 mol / L, and more preferably in the range of 1×10 -5 mol / L to 1×10 -6 mol / L.

[0183] The absorption spectrum can be measured by a general ultraviolet-visible spectrophotometer. In addition, the emission spectrum can be measured by a general fluorescence spectrophotometer. Further, the measurement of the fluorescence quantum yield is preferably carried out using an absolute quantum yield measurement device using an integrating sphere. In order to achieve high color purity, it is preferable that the emission spectrum of the light emitted by the methylene pyrrole boron coordination compound upon irradiation with excitation light is sharp.

[0184] In addition, for top-emitting elements that are becoming mainstream in display devices and lighting devices, high brightness and high color purity can be achieved through the resonance effect obtained from the microcavity structure. However, if the emission spectrum is sharp, this resonance effect is more strongly manifested, which is beneficial for high efficiency. From this perspective, the half-width of the emission spectrum is preferably 60 nm or less, more preferably 50 nm or less, further preferably 45 nm or less, and particularly preferably 28 nm or less.

[0185] The luminous efficiency of the light-emitting element depends on the fluorescence quantum yield of the light-emitting material itself. Therefore, it is desirable that the fluorescence quantum yield of the light-emitting material is as close as possible to 100%. The methylene pyrrole boron coordination compound represented by the general formula (2) can reduce thermal deactivation by suppressing the rotation / vibration at the bridgehead position, thereby obtaining a high fluorescence quantum yield. From the above perspective, the fluorescence quantum yield of the methylene pyrrole boron coordination compound is preferably 90% or more, more preferably 95% or more. However, the fluorescence quantum yield shown here is measured by an absolute quantum yield measuring device for a diluted solution using toluene as a solvent.

[0186] In addition, when the first compound is a thermally activated delayed fluorescence compound, the light-emitting layer can further contain a compound (hereinafter sometimes referred to as a "third compound") whose singlet energy (which refers to the energy difference between the lowest excited singlet state and the ground state. The same applies hereinafter) is greater than that of the first compound. Thus, the third compound can have the function of restricting the energy of the light-emitting material within the light-emitting layer, enabling efficient light emission. In addition, it is preferred that the lowest excited triplet energy (which refers to the energy difference between the lowest excited triplet state and the ground state. The same applies hereinafter) of the third compound is greater than that of the first compound. As such a third compound, an organic compound with high charge transport ability and high glass transition temperature is preferred.

[0187] These third compounds can be composed of a single material or two or more materials. When two or more materials are used as the third compound, a combination of an electron-transporting third compound and a hole-transporting third compound is preferred. By combining the electron-transporting third compound and the hole-transporting third compound in an appropriate mixing ratio, the charge balance within the light-emitting layer can be adjusted, the skew of the light-emitting region can be suppressed, thereby improving the reliability of the light-emitting element and enhancing the durability. In addition, an excited coordination compound can be formed between the electron-transporting third compound and the hole-transporting third compound.

[0188] From the above perspective, it is preferred that the first compound and the third compound respectively satisfy the relational expressions of the following formulas 1 to 4. In addition, it is more preferred to satisfy formulas 1 and 2, further preferred to satisfy formulas 3 and 4. In addition, it is even more preferred to satisfy all of formulas 1 to 4.

[0189] S1(Third compound with electron-transporting property) > S1(First compound) (Formula 1)

[0190] S1(Third compound with hole-transporting property) > S1(First compound) (Formula 2)

[0191] T1(Third compound with electron-transporting property) > T1(First compound) (Formula 3)

[0192] T1(Third compound with hole-transporting property) > T1(First compound) (Formula 4)

[0193] Here, S1 represents the energy level of the lowest excited singlet state of each compound, and T1 represents the energy level of the lowest excited triplet state of each compound.

[0194] Examples of the third compound with electron-transporting property include compounds containing a heteroaromatic ring with a deficiency of π electrons, etc. Specifically, heterocyclic compounds having a polyazole skeleton, heterocyclic compounds having a quinoxaline skeleton or a dibenzoquinoxaline skeleton, heterocyclic compounds having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton), and heterocyclic compounds having a pyridine skeleton can be exemplified. In addition, examples of the third compound with hole-transporting property include compounds containing a heteroaromatic ring with an excess of π electrons, etc. Specifically, compounds having a carbazole skeleton can be exemplified.

[0195] As described above, the formation method of each layer constituting the light-emitting element of the present invention can be either a dry process or a wet process, and there is no particular limitation on resistance heating evaporation, electron beam evaporation, sputtering, molecular lamination method, coating method, inkjet method, printing method, etc. Generally, from the viewpoint of device characteristics, resistance heating evaporation is preferred. Since the thickness of the organic layer depends on the resistance value of the light-emitting material, it cannot be particularly limited, but it is preferably 1 to 1000 nm. The film thicknesses of the light-emitting layer, electron-transporting layer, and hole-transporting layer are each preferably 1 nm or more and 200 nm or less, and more preferably 5 nm or more and 100 nm or less.

[0196] Examples

[0197] Hereinafter, examples are given to specifically illustrate the present invention, but the present invention is not limited thereto. First, the evaluation method will be described.

[0198] (1) Nuclear magnetic resonance analysis (NMR)

[0199] Regarding the white solid obtained in Synthesis Example 2, a 400 MHz NMR spectrum was measured using a JNM-AL400 type nuclear magnetic resonance apparatus (manufactured by JEOL Ltd.). The chemical shift was based on tetramethylsilane and expressed as δ (unit: ppm), and the signals were expressed as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), br (broad peak), dd (doubled doublet), and dt (doubled triplet), respectively. In addition, the solvent name shown in the NMR data indicates the solvent used for the measurement.

[0200] (2) Powder X-ray diffraction

[0201] The white solids obtained in each of the Examples and Comparative Examples were filled into a sample plate (material: silicon; depth: 0.2 mm) of a powder X-ray diffractometer (Rigaku Corporation; 2200 / RINT ultima+PC), and the surface was flattened to prepare a measurement sample. The powder X-ray diffraction was measured under the following conditions.

[0202] X-ray source: CuKα ray

[0203] * Using a curved crystal monochromator (graphite)

[0204] Output: 40 kV / 50 mA

[0205] Divergence slit: 1 / 2°

[0206] Divergence longitudinal limiting slit: 5 mm

[0207] Scattering slit: 1 / 2°

[0208] Receiving slit: 0.15 mm

[0209] Detector: Scintillation counter

[0210] Scanning mode: 2θ / θ scan, continuous scan

[0211] Measurement range (2θ): 2 to 30°

[0212] Scanning speed (2θ): 20° / min

[0213] Counting step size (2θ): 0.04°.

[0214] (3) Endothermic peak

[0215] Regarding the white solids obtained in each of the Examples and Comparative Examples, simultaneous differential thermal-thermogravimetric measurement was performed using a differential thermal-thermogravimetric simultaneous measurement apparatus (TG-DTA apparatus; Rigaku Corporation; TG8120 Smart Loader), and the temperature at the peak of the DTA curve was taken as the endothermic peak.

[0216] Heating rate: 5 °C / min

[0217] Atmosphere: Dry nitrogen (flow rate: 100 mL / min)

[0218] Specimen unit: Aluminum open unit

[0219] Specimen amount: 5 - 15 mg.

[0220] (4) Chemical purity

[0221] Regarding the white solids obtained through each example and comparative example, the chemical purity was determined using high performance liquid chromatography (hereinafter, HPLC). The area percentage of the measurement target peak with respect to all peaks except the blank peak and the residual solvent peak was defined as the chemical purity. In addition, the specimen for HPLC analysis was prepared by dissolving 4 mg of the white solid obtained through each example and comparative example in 40 mL of tetrahydrofuran.

[0222] HPLC: LC - 2010CHT (Shimadzu Corporation)

[0223] Detection: UV (254 nm)

[0224] Column: Mightysil RP - 8GP (Kanto Chemical Co., Inc.)

[0225] Column size: 250×4.6 mm (5 μm)

[0226] Column temperature: 45 °C

[0227] Mobile phase: Solution A 0.1% phosphoric acid aqueous solution (weight ratio)

[0228] Solution B Acetonitrile / tetrahydrofuran = 80 / 20 (volume ratio)

[0229] Elution conditions: A / B = 55 / 45 → 0 / 100 (volume ratio); 0 → 25 minutes, linear gradient

[0230] A / B = 0 / 100 (volume ratio); 25 → 30 minutes, constant

[0231] A / B = 0 / 100 → 55 / 45 (volume ratio); 30 → 31 minutes, linear gradient

[0232] A / B = 55 / 45 (volume ratio), 31 → 35 minutes, constant

[0233] Flow rate: 1.0 mL / min

[0234] Injection volume: 10 μL.

[0235] (5) Residual solvent amount

[0236] Regarding the white solids obtained through each of the examples and comparative examples, NMR measurements were performed, and the molar ratios were calculated from the arbitrary peak integral values of the compound to be measured and the residual solvents respectively. The amount of residual solvent was calculated from the weight and molar ratio of the white solids obtained through each of the examples and comparative examples. Additionally, in the case where multiple residual solvents were confirmed, the total value was calculated as their sum.

[0237] Next, the synthesis examples of the precursor substances of the crystals of the present invention, the examples and comparative examples of the production of the crystals of the present invention, and their evaluation results will be described.

[0238] (Synthesis Example 1) Synthesis of 2-phenyl-1,10-phenanthroline:

[0239] Under an argon atmosphere, a phenyl lithium solution (1.07 M, 100 mL) was added to a toluene (250 mL) solution of 1,10-phenanthroline (9.64 g), and the mixture was stirred at 0 °C for 1.5 hours. Then, water (150 mL) was added to the reaction mixture, and after extracting 3 times with dichloromethane (200 mL), the organic layer was washed with saturated brine (150 mL), and the organic layer was concentrated. Manganese dioxide (93 g) was added to a dichloromethane (300 mL) solution of the obtained concentrate, and the mixture was stirred at room temperature for 56 hours. Then, the reaction mixture was filtered, the residue was washed with dichloromethane (500 mL), and the filtrate and the washing solution were combined and concentrated. The obtained concentrate was suspended in ethyl acetate (30 mL) and stirred at 0 °C. After filtering the precipitated product, it was dried under reduced pressure at 80 °C to obtain 9.44 g of 2-phenyl-1,10-phenanthroline as a white solid.

[0240] (Synthesis Example 2) Synthesis of 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene:

[0241] Under an argon atmosphere, n-butyllithium (1.52 M, 17 mL) was added to a hexane (35 mL) solution of 1,3-dibromobenzene (1.2 mL), and the mixture was stirred under reflux for 1 hour. Then, after cooling the reaction mixture to 0 °C, a tetrahydrofuran (100 mL) solution of 2-phenyl-1,10-phenanthroline (5.10 g) was added, and the mixture was stirred at 0 °C for 2 hours. Then, water (100 mL) was added to the reaction mixture, and after extracting 3 times with dichloromethane (150 mL), the organic layer was washed with saturated brine (150 mL), and the organic layer was concentrated. Manganese dioxide (34.8 g) was added to a dichloromethane (180 mL) solution of the obtained concentrate, and the mixture was stirred at room temperature for 12 hours. Then, the reaction mixture was filtered, the residue was washed with dichloromethane (750 mL), and the filtrate and the washing solution were combined and concentrated.

[0242] The obtained concentrate was suspended in a dichloromethane / chloroform mixed solution (volume ratio 1 / 10, 85 mL), and stirred at 0 °C. After filtering the precipitate, it was dried under reduced pressure at 100 °C, and 3.25 g of 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene was obtained as a white solid. The NMR chemical shifts of the obtained compound are shown below.

[0243] 1H-NMR(CDCl 3 , ppm): 9.75 (s, 1H), 8.72 (dd, 2H), 8.57 - 8.17 (m, 12H), 7.90 - 7.82 (m, 5H), 7.61 - 7.48 (m, 6H).

[0244] (Example 1)

[0245] Under an argon atmosphere, 1,3-dimethyl-2-imidazolidinone (4.9 mL, specific gravity 1.05) and toluene (8.7 mL, specific gravity 0.86) were added to 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene (1.28 g) obtained by Synthesis Example 2, and the mixture was stirred at 110 °C for 0.5 hour. Then, it was cooled to 0 °C over 1 hour and stirred at 0 °C for 1 hour. After filtering the precipitate, it was dried under reduced pressure at 20 °C. Tetrahydrofuran (16.7 mL, specific gravity 0.89) was added to the obtained precipitate, and the mixture was heated under reflux and stirred for 2 hours. Then, it was cooled to 0 °C over 1 hour and stirred at 0 °C for 1 hour. After filtering the precipitate, it was dried under reduced pressure at 100 °C to obtain a white solid (yield 0.71 g, recovery rate 55%).

[0246] Regarding the obtained white solid, powder X-ray diffraction and measurement of the endothermic peak were performed by the above method. The measurement results are as described below, and it was confirmed to be B-type crystal. The powder X-ray diffraction pattern is shown in Figure 1 and the differential thermal analysis curve is shown in Figure 2 .

[0247] Diffraction angle 2θ (°): 6.7, 8.2, 13.7, 17.7, 22.2

[0248] Endothermic peak: 182 °C

[0249] In addition, the results of evaluating the chemical purity and residual solvent amount by the above method are shown in Table 1.

[0250] (Example 2)

[0251] Under an argon atmosphere, 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene (0.97 g) obtained by Synthesis Example 2 was added with 1,3-dimethyl-2-imidazolidinone (2.2 mL, specific gravity 1.05) and toluene (6.6 mL, specific gravity 0.86), and stirred at 120 °C for 0.5 hour. Then, it was cooled to 0 °C over 3 hours and stirred at 0 °C for 2 hours. After filtering the precipitate, it was dried under reduced pressure at 100 °C. Tetrahydrofuran (7.7 mL, specific gravity 0.89) was added to the obtained precipitate, and the mixture was heated to reflux and stirred for 2 hours. Then, it was cooled to 0 °C over 3 hours and stirred at 0 °C for 2 hours. After filtering the precipitate, it was dried under reduced pressure at 100 °C to obtain a white solid (yield 0.70 g, recovery rate 72%).

[0252] Regarding the obtained white solid, powder X-ray diffraction and endothermic peak were measured by the above method. The measurement results are as described below and can be confirmed as B-type crystal.

[0253] Diffraction angle 2θ (°): 6.7, 8.2, 13.7, 17.7, 22.2

[0254] Endothermic peak: 182 °C

[0255] In addition, the results of evaluating the chemical purity and residual solvent amount by the above method are shown in Table 1.

[0256] (Example 3)

[0257] Under an argon atmosphere, 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene (0.30 g) obtained by Synthesis Example 2 was added with 1,3-dimethyl-2-imidazolidinone (1.1 mL, specific gravity 1.05) and anisole (2.1 mL, specific gravity 0.99), and stirred at 100 °C for 0.5 hour. Then, it was cooled to 0 °C over 1 hour and stirred at 0 °C for 2 hours. After filtering the precipitate, it was dried under reduced pressure at 100 °C to obtain a white solid (yield 0.24 g, recovery rate 80%).

[0258] Regarding the obtained white solid, powder X-ray diffraction and endothermic peak were measured by the above method. The measurement results are as described below and can be confirmed as C-type crystal. The powder X-ray diffraction pattern is shown in Figure 3 and the differential thermal analysis curve is shown in Figure 4 .

[0259] Diffraction angle 2θ (°): 5.0, 7.5, 8.7, 12.5, 17.3

[0260] Endothermic peak: 245 °C

[0261] In addition, the results of evaluating the chemical purity and the residual solvent amount by the above method are shown in Table 1.

[0262] (Example 4)

[0263] Under an argon atmosphere, N-methylpyrrolidone (1.1 mL, specific gravity 1.03) and anisole (2.1 mL, specific gravity 0.99) were added to 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene (0.30 g) obtained in Synthesis Example 2, and the mixture was stirred at 100 °C for 0.5 hour. Then, it was cooled to 0 °C over 1 hour and stirred at 0 °C for 2 hours. After filtering the precipitate, it was dried under reduced pressure at 100 °C to obtain a white solid (yield 0.23 g, recovery rate 77%).

[0264] Regarding the obtained white solid, powder X-ray diffraction and measurement of the endothermic peak were performed by the above method, and the measurement results are as described below, and it was confirmed to be a C-type crystal.

[0265] Diffraction angle 2θ (°): 5.0, 7.5, 8.7, 12.5, 17.3

[0266] Endothermic peak: 245 °C

[0267] In addition, the results of evaluating the chemical purity and the residual solvent amount by the above method are shown in Table 1.

[0268] (Example 5)

[0269] Under an argon atmosphere, N,N-dimethylacetamide (1.1 mL, specific gravity 0.94) and anisole (2.1 mL, specific gravity 0.99) were added to 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene (0.30 g) obtained in Synthesis Example 2, and the mixture was stirred at 100 °C for 0.5 hour. Then, it was cooled to 0 °C over 1 hour and stirred at 0 °C for 2 hours. After filtering the precipitate, it was dried under reduced pressure at 100 °C to obtain a white solid (yield 0.25 g, recovery rate 83%).

[0270] Regarding the obtained white solid, powder X-ray diffraction and measurement of the endothermic peak were performed by the above method, and the measurement results are as described below, and it was confirmed to be a C-type crystal.

[0271] Diffraction angle 2θ (°): 5.0, 7.5, 8.7, 12.5, 17.3

[0272] Endothermic peak: 245 °C

[0273] In addition, the results of evaluating the chemical purity and the residual solvent amount by the above method are shown in Table 1.

[0274] (Example 6)

[0275] Under an argon atmosphere, 1,3 - bis(9 - phenyl - 1,10 - phenanthrolin - 2 - yl)benzene (0.30 g) obtained through Synthesis Example 2 was added with 1,3 - dimethyl - 2 - imidazolidinone (1.1 mL, specific gravity 1.05) and anisole (2.1 mL, specific gravity 0.99), and stirred at 100 °C for 0.5 hour. Then, it was cooled to 0 °C over 4 hours and stirred at 0 °C for 2 hours. After filtering the precipitate, it was dried under reduced pressure at 25 °C to obtain a white solid (yield 0.30 g, recovery rate 100%).

[0276] Regarding the obtained white solid, powder X - ray diffraction and measurement of the endothermic peak were carried out by the above - mentioned method. The measurement results are as follows and can be confirmed as E - type crystals. The powder X - ray diffraction pattern is shown in Figure 5 and the differential thermal analysis curve is shown in Figure 6 .

[0277] Diffraction angle 2θ (°): 5.2, 7.0, 16.4, 20.0, 23.6

[0278] Endothermic peak: 96 °C

[0279] Under an argon atmosphere, 1,3 - bis(9 - phenyl - 1,10 - phenanthrolin - 2 - yl)benzene (0.15 g) obtained through the above information was dried under reduced pressure at 100 °C to obtain a white solid (yield 0.12 g, recovery rate 80%).

[0280] Regarding the obtained white solid, powder X - ray diffraction and measurement of the endothermic peak were carried out by the above - mentioned method. The measurement results are as follows and can be confirmed as C - type crystals.

[0281] Diffraction angle 2θ (°): 5.0, 7.5, 8.7, 12.5, 17.3

[0282] Endothermic peak: 245 °C

[0283] In addition, the results of evaluating the chemical purity and the residual solvent amount by the above - mentioned method are shown in Table 2.

[0284] (Comparative Example 1)

[0285] In an argon atmosphere, 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene (0.30 g) obtained in Synthesis Example 2 was added with 1,3-dimethyl-2-imidazolidinone (0.9 mL, specific gravity 1.05) and anisole (2.1 mL, specific gravity 0.99), and the mixture was stirred at 100 °C for 0.5 hour. Then, it was cooled to 0 °C over 1 hour and stirred at 0 °C for 2 hours. After filtering the precipitate, it was dried under reduced pressure at 100 °C to obtain a white solid (yield 0.27 g, recovery rate 90%).

[0286] Regarding the obtained white solid, powder X-ray diffraction and measurement of the endothermic peak were carried out by the above method. As a result, the measurement results are as described below, and it was confirmed to be a crystal form different from B-type crystal and C-type crystal (referred to as "D-type crystal"). The powder X-ray diffraction pattern is shown in Figure 7 and the differential thermal analysis curve is shown in Figure 8 .

[0287] Diffraction angle 2θ (°): 4.8, 7.2, 9.5, 22.9, 27.6

[0288] Endothermic peak: 173 °C

[0289] In addition, the results of evaluating the chemical purity and the residual solvent amount by the above method are shown in Table 2.

[0290] (Comparative Example 2)

[0291] In an argon atmosphere, methanol (18 mL, specific gravity 0.79) was added to 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene (0.70 g) obtained in Synthesis Example 2, and the mixture was stirred at 20 °C for 2 hours. After filtering the precipitate, it was dried under reduced pressure at 100 °C to obtain a white solid (yield 0.67 g, recovery rate 96%). Regarding the obtained white solid, powder X-ray diffraction was carried out by the above method. The measurement results are shown in Figure 9 . As shown in Figure 9 , no characteristic diffraction peak was confirmed, and it was amorphous. In addition, the results of evaluating the chemical purity and the residual solvent amount by the above method are shown in Table 2.

[0292] (Comparative Example 3)

[0293] Regarding 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene obtained in Synthesis Example 2, powder X-ray diffraction was carried out by the above method. As a result, similarly to Comparative Example 2, no characteristic diffraction peak was confirmed, and it was amorphous. In addition, the results of evaluating the chemical purity and the residual solvent amount by the above method are shown in Table 2. The main preparation methods and evaluation results of Examples 1 to 7 and Comparative Examples 1 to 3 are shown in Tables 1 and 2.

[0294]

[0295]

[0296] As shown in Table 1 and Table 2, it can be seen that the phenanthroline derivative synthesized by the conventional method and the phenanthroline derivative washed with methanol solvent are amorphous and have a small amount of residual solvent, but have a low chemical purity. On the other hand, it can be seen that although the D-type crystal of Comparative Example 1 has a high chemical purity, it has a large amount of residual solvent. Therefore, when obtaining a phenanthroline derivative with a high chemical purity and a small amount of residual solvent, simply crystallizing the amorphous form is insufficient, and it is necessary to select the B-type crystal or C-type crystal with a small amount of residual solvent. In addition, in Example 6, the E-type crystal is prone to polymorphic transformation under the condition of reduced pressure drying at 100 °C. Therefore, it can be seen that the E-type crystal is useful as a precursor for obtaining the C-type crystal by low-temperature drying.

[0297] Next, examples and comparative examples of a light-emitting device in which an electron transport layer is formed using the above B-type crystal or C-type crystal and a thermally activated delayed fluorescence material is used as a light-emitting layer will be described.

[0298] In addition, the methylene pyrrole boron coordination compound used in the following examples and comparative examples is the compound shown below. Its properties are shown in Table 3.

[0299]

[0300]

[0301] Table 3

[0302]

[0303] (Example 7)

[0304] A glass substrate (manufactured by Geomatec Co., Ltd., 11 Ω / □, sputtered product) on which an ITO transparent conductive film was deposited to a thickness of 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically washed with "Semicoclean 56" (trade name, manufactured by Furuchi Chemical Co., Ltd.) for 15 minutes and then washed with ultrapure water. The substrate was subjected to ultraviolet-ozone treatment for 1 hour immediately before fabricating the device, placed in a vacuum evaporation apparatus, and evacuated until the vacuum degree in the apparatus reached 5 × 10 - 4Up to below Pa. By the resistance heating method, first, as a hole injection layer, 10 nm of HAT-CN6 was evaporated, and as a hole transport layer, 180 nm of HT-1 was evaporated. Next, as a light-emitting layer, H-1 as a host material, compound D-1 as a dopant compound, and compound H-2 as a TADF material were evaporated to a thickness of 40 nm in a weight ratio of 80:1:19. Further, as an electron transport layer, crystals (C-type crystals) of compound ET-1 as a phenanthroline derivative were used to be evaporated to a thickness of 35 nm and laminated. Next, after evaporating 0.5 nm of 2E-1 as an electron injection layer, magnesium and silver were co-evaporated by 1000 nm to form a cathode, and a 5×5 mm square element was fabricated.

[0305] Let this light-emitting element be at 1000 cd / m 2 The external quantum efficiency during light emission was 11.4%. In addition, the structures of HAT-CN6, HT-1, H-1, H-2, ET-1, and 2E-1 are shown below.

[0306]

[0307] (Examples 8 to 10)

[0308] As the crystal form of ET-1 as a phenanthroline derivative, the crystals of the crystal form described in Table 1 were used, and as the doping material for the light-emitting layer, the compounds described in Table 3 were used. Except for this, a light-emitting element was fabricated by operating in the same manner as in Example 7 and evaluated. The results are shown in Table 4.

[0309] (Example 11)

[0310] A glass substrate (manufactured by Geomatec Co., Ltd., 11 Ω / □, sputtered product) on which a 165-nm ITO transparent conductive film was deposited was cut into 38×46 mm and etched. The obtained substrate was ultrasonically washed with "Semicoclean 56" (trade name, manufactured by Furuchi Chemical Co., Ltd.) for 15 minutes and then washed with ultrapure water. This substrate was subjected to ultraviolet-ozone treatment for 1 hour immediately before fabricating the element, set in a vacuum evaporation apparatus, and evacuated until the vacuum degree in the apparatus became 5×10 -4Up to below Pa. By the resistance heating method, first, as a hole injection layer, 10 nm of HAT-CN6 was vapor-deposited, and as a hole transport layer, 40 nm of HT-1 was vapor-deposited. Next, as a light-emitting layer, H-1 as a host material, compound D-6 as a dopant compound, and compound H-3 as a TADF material were vapor-deposited to a thickness of 30 nm in a weight ratio of 80:1:19. Further, as an electron transport layer, crystals (C-type crystals) of compound ET-1 as a phenanthroline derivative were used and vapor-deposited to a thickness of 50 nm for lamination. Next, after vapor-depositing 0.5 nm of 2E-1 as an electron injection layer, magnesium and silver were co-vapor-deposited at 1000 nm to form a cathode, and a 5×5 mm square element was fabricated.

[0311] Let this light-emitting element be at 1000 cd / m 2 The external quantum efficiency during light emission was 9.2%. In addition, the structure of H-3 is shown below.

[0312]

[0313] (Examples 12 to 14)

[0314] As the crystal form of ET-1 as a phenanthroline derivative, crystals of the crystal forms described in Table 1 were used, and as a doping material for the light-emitting layer, the compounds described in Table 3 were used. Except for this, light-emitting elements were fabricated by operating in the same manner as in Example 11 and evaluated. The results are shown in Table 4.

[0315] (Comparative Examples 4 and 5)

[0316] As the crystal form of ET-1 as a phenanthroline derivative, the substances of the crystal forms described in Table 2 were used, and as a doping material for the light-emitting layer, the compounds described in Table 3 were used. Except for this, light-emitting elements were fabricated by operating in the same manner as in Example 7 and evaluated. The results are shown in Table 4.

[0317] (Comparative Examples 6 and 7)

[0318] As the crystal form of ET-1 as a phenanthroline derivative, the substances of the crystal forms described in Table 2 were used, and as a doping material for the light-emitting layer, the compounds described in Table 3 were used. Except for this, light-emitting elements were fabricated by operating in the same manner as in Example 11 and evaluated. The results are shown in Table 4.

[0319]

[0320] As can be seen from Table 4, Examples 7 to 14 have higher external quantum efficiencies compared to Comparative Examples 4 to 7 that use the same light-emitting layer. That is, as can be seen by referring to Table 4, Examples 7 to 14 in which the B-type crystal or C-type crystal of compound ET-1 is used as the electron transport material, compared to Comparative Examples 4 to 7 in which the D-type crystal or amorphous form of compound ET-1 is used as the electron transport material, it can be seen that in the case of using any thermally activated delayed fluorescence material for the light-emitting layer, a light-emitting element with a significantly improved external quantum efficiency can be obtained.

[0321] Next, Examples and Comparative Examples of a light-emitting element in which an electron injection layer is formed using the above B-type crystal or C-type crystal and a thermally activated delayed fluorescence material is used as the light-emitting layer will be described.

[0322] (Example 15)

[0323] A glass substrate (manufactured by Geomatec Co., Ltd., 11 Ω / sq., sputtered product) on which a 165-nm-thick ITO transparent conductive film was deposited was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically washed with "Semicoclean 56" (trade name, manufactured by Furuchi Chemical Co., Ltd.) for 15 minutes and then washed with ultrapure water. The substrate was subjected to ultraviolet-ozone treatment for 1 hour immediately before fabricating the element, placed in a vacuum evaporation apparatus, and evacuated until the vacuum degree in the apparatus reached 5 × 10 -4 Pa or less. By the resistance heating method, first, 10 nm of HAT-CN6 was evaporated as the hole injection layer, and 180 nm of HT-1 was evaporated as the hole transport layer. Next, as the light-emitting layer, H-1 as the host material, compound D-1 as the dopant compound, and compound H-2 as the TADF material were evaporated to a thickness of 40 nm in a weight ratio of 80:1:19. Further, as the electron transport layer, compound ET-2 was used as the electron transport material, 2E-1 was used as the donor material, and they were laminated to a thickness of 35 nm such that the evaporation rate ratio of compound ET-2 to 2E-1 was 1:1. Next, as the electron injection layer, the crystal of compound ET-1 (C-type crystal) as a phenanthroline derivative was used, metallic lithium was used as the donor material, and after evaporating 5 nm such that the evaporation rate ratio of compound ET-1 to metallic lithium was 99:1, magnesium and silver were co-evaporated for 1000 nm to form the cathode, and a 5 × 5 mm square element was fabricated.

[0324] The external quantum efficiency of this light-emitting element during light emission at 1000 cd / m 2 was 14.4%. In addition, the following shows the structure of ET-2.

[0325]

[0326] (Examples 16 to 18)

[0327] As the crystal form of ET-1 which is a phenanthroline derivative, the crystal of the crystal form described in Table 1 was used, and as the doping material for the light-emitting layer, the compound described in Table 3 was used. Except for this, a light-emitting element was fabricated by operating in the same manner as in Example 15 and evaluated. The results are shown in Table 5.

[0328] (Example 19)

[0329] A glass substrate (manufactured by Geomatec Co., Ltd., 11 Ω / sq., sputtered product) on which a 165-nm-thick ITO transparent conductive film was deposited was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically washed with "Semicoclean 56" (trade name, manufactured by Furuchi Chemical Co., Ltd.) for 15 minutes and then washed with ultrapure water. The substrate was subjected to ultraviolet-ozone treatment for 1 hour immediately before fabricating the device, placed in a vacuum evaporation apparatus, and evacuated until the vacuum degree inside the apparatus reached 5 × 10 -4 Pa or less. By the resistance heating method, first, 10 nm of HAT-CN6 was evaporated as the hole injection layer, and 40 nm of HT-1 was evaporated as the hole transport layer. Next, as the light-emitting layer, H-1 as the host material, compound D-6 as the dopant compound, and compound H-3 as the TADF material were evaporated to a thickness of 30 nm in a weight ratio of 80:1:19. Further, as the electron transport layer, compound ET-2 was used as the electron transport material, 2E-1 was used as the donor material, and they were laminated to a thickness of 50 nm in a vapor deposition rate ratio of compound ET-2 to 2E-1 of 1:1. Next, as the electron injection layer, metallic lithium was used as the donor material, and the crystal of ET-1 which is a phenanthroline derivative (C-type crystal) was evaporated 5 nm in a vapor deposition rate ratio of compound ET-1 to metallic lithium of 99:1, and then magnesium and silver were co-evaporated for 1000 nm to form the cathode, and a 5 × 5 mm square device was fabricated.

[0330] The external quantum efficiency during light emission of this light-emitting element was 12.2% at 1000 cd / m 2

[0331] (Examples 20 to 22)

[0332] As the crystal form of ET-1 which is a phenanthroline derivative, the crystal of the crystal form described in Table 1 was used, and as the doping material for the light-emitting layer, the compound described in Table 3 was used. Except for this, a light-emitting element was fabricated by operating in the same manner as in Example 19 and evaluated. The results are shown in Table 5.

[0333] (Comparative Examples 8 and 9)

[0334] ​As the crystal form of ET-1, a substance having the crystal form described in Table 2 was used, and as the doping material for the light-emitting layer, the compound described in Table 3 was used. Other than that, a light-emitting element was fabricated by operating in the same manner as in Example 15, and evaluation was performed. The results are shown in Table 5.

[0335] (Comparative Examples 10 and 11)

[0336] As the crystal form of ET-1, a substance having the crystal form described in Table 2 was used, and as the doping material for the light-emitting layer, the compound described in Table 3 was used. Other than that, a light-emitting element was fabricated by operating in the same manner as in Example 19, and evaluation was performed. The results are shown in Table 5.

[0337]

[0338] As can be seen from Table 5, Examples 15 to 22 all have a higher external quantum efficiency compared to Comparative Examples 8 to 9 using the same light-emitting layer. That is, as can be seen by referring to Table 5, Examples 15 to 22 using the B-type crystal or C-type crystal of compound ET-1 as the electron injection material and Comparative Examples 8 to 11 using the D-type crystal or amorphous form of compound ET-1 as the electron injection material can obtain a light-emitting element with a significantly improved external quantum efficiency in the case of using any thermally activated delayed fluorescence material for the light-emitting layer.

[0339] Next, an example of a light-emitting element will be described in which a charge generation layer of a tandem fluorescent light-emitting element is formed using the above B-type crystal or C-type crystal, and a thermally activated delayed fluorescence material is used as the light-emitting layer.

[0340] (Example 23)

[0341] A glass substrate (manufactured by Geomatec Co., Ltd., 11 Ω / square, sputtered product) on which an ITO transparent conductive film was deposited to a thickness of 165 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically washed with "Semicoclean 56" (trade name, manufactured by Furuchi Chemical Co., Ltd.) for 15 minutes and then washed with ultrapure water. The substrate was subjected to ultraviolet-ozone treatment for 1 hour immediately before fabricating the element, placed in a vacuum evaporation apparatus, and evacuated until the vacuum degree in the apparatus became 5 × 10 -4Up to Pa. By the resistance heating method, first, 5 nm of HAT-CN6 was vapor-deposited as a hole injection layer, and then 50 nm of HT-1 was vapor-deposited as a hole transport layer. Next, as a light-emitting layer, H-1 as a host material, compound D-1 as a dopant compound, and compound H-2 as a TADF material were vapor-deposited to a thickness of 20 nm in a weight ratio of 80:1:19. Further, as an electron transport layer, compound ET-2 was used as the electron transport material and 2E-1 was used as the donor material, and they were laminated to a thickness of 35 nm in a vapor deposition rate ratio of compound ET-2 to 2E-1 of 1:1. Then, as an n-type charge generation layer, the n-type host used the crystal of ET-1 as a phenanthroline derivative (C-type crystal: Example 6), and the n-type dopant used metallic lithium, and they were laminated 10 nm in a vapor deposition rate ratio of compound ET-1 to metallic lithium of 99:1. Further, 10 nm of HAT-CN6 was laminated as a p-type charge light-emitting layer. On it, a 50-nm hole transport layer, a 20-nm light-emitting layer, and a 35-nm electron transport layer were vapor-deposited in the same manner as above. Next, after vapor-depositing 0.5 nm of 2E-1 as an electron injection layer, magnesium and silver were co-evaporated for 1000 nm to form a cathode, and a 5×5 mm square tandem-type fluorescent light-emitting element was fabricated.

[0342] Let this light-emitting element be at 1000 cd / m 2 The external quantum efficiency during light emission was 16.2%. Compared with Example 15 having only one light-emitting layer, an increase in the external quantum efficiency was confirmed.

[0343] (Example 24)

[0344] A glass substrate (manufactured by Geomatec Co., Ltd., 11 Ω / □, sputtered product) with a 165-nm ITO transparent conductive film deposited thereon was cut into 38×46 mm and etched. The obtained substrate was ultrasonically washed with "Semicoclean 56" (trade name, manufactured by Furuchi Chemical Co., Ltd.) for 15 minutes and then washed with ultrapure water. The substrate was subjected to ultraviolet-ozone treatment for 1 hour immediately before fabricating the element, placed in a vacuum evaporation apparatus, and evacuated until the vacuum degree in the apparatus reached 5×10 -4Up to below Pa. By the resistance heating method, first, as a hole injection layer, 5 nm of HAT-CN6 was vapor-deposited, and then, as a hole transport layer, 50 nm of HT-1 was vapor-deposited. Next, as a light-emitting layer, H-1 as a host material, compound D-6 as a doping material, and compound H-3 as a TADF material were vapor-deposited to a thickness of 30 nm in a weight ratio of 80:1:19. As an electron transport layer, crystals (C-type crystals) of ET-1, a phenanthroline derivative, were laminated to a thickness of 35 nm. Next, as an n-type charge generation layer, crystals (C-type crystals: Example 6) of ET-1, a phenanthroline derivative as an n-type host, and metallic lithium as an n-type dopant were laminated in a vapor deposition rate ratio of 99:1 to a thickness of 10 nm. Further, as a p-type charge generation layer, 10 nm of HAT-CN6 was laminated. On this, a 50-nm hole transport layer, a 30-nm light-emitting layer, and 35-nm ET-1 (C-type crystals) as an electron transport layer were vapor-deposited in the same manner as above. Next, after 0.5 nm of 2E-1 was vapor-deposited as an electron injection layer, magnesium and silver were co-vapor-deposited at 1000 nm to form a cathode, and a 5 mm × 5 mm square tandem light-emitting element was fabricated.

[0345] When this light-emitting element is at 1000 cd / m 2 The external quantum efficiency during light emission is 11.3%. Compared with Example 11 in which there was only one light-emitting layer, an increase in the external quantum efficiency was confirmed.

[0346] Industrial Applicability

[0347] The crystals of the phenanthroline derivative of the present invention show extremely high chemical purity and have a small amount of residual solvent compared with phenanthroline derivatives obtained by conventional methods. Therefore, bumping during sublimation purification can be suppressed, and it can also be used in industrial production. In addition, the phenanthroline derivative obtained by sublimation purification of the crystals of the phenanthroline derivative of the present invention can be suitably used as a light-emitting element material used in fields such as display elements, flat panel displays, backlights, lighting, interior decorations, signs, billboards, electronic cameras, and optical signal generators due to its high chemical purity.

Claims

1. A C-type crystal of a phenanthroline derivative having a structure represented by the general formula (1) and having peaks at diffraction angles 2θ of 5.0 ± 0.2, 7.5 ± 0.2, 8.7 ± 0.2, 12.5 ± 0.2, and 17.3 ± 0.2 in powder X-ray diffraction, wherein, the unit of the diffraction angle 2θ is °, in the general formula (1), X represents a phenylene group, and the phenanthroline derivative is 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene.

2. The C-type crystal of the phenanthroline derivative according to claim 1, which has an endothermic peak in the range of 243 to 247 °C in simultaneous differential thermal-thermogravimetric measurement.

3. A light-emitting element that emits light by electric energy, comprising: an anode, a cathode, and the following layer present between the cathode and the anode: a light-emitting layer containing a thermally activated delayed fluorescence material; and at least one layer selected from an electron transport layer, an electron injection layer, and a charge generation layer and containing a phenanthroline derivative derived from the C-type crystal according to claim 1 or 2.

4. The light-emitting element according to claim 3, further containing a methylene pyrrole boron coordination compound represented by the following general formula (2) in the light-emitting layer, wherein, in the general formula (2), X 1 is a nitrogen atom or a carbon atom, where a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted heteroaryl group, a halogen atom, a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted amino group, a nitro group, a cyano group, a substituted or unsubstituted silyl group, or a substituted or unsubstituted siloxy group is bonded to the carbon atom; R 1 ~R 6 Each independently represents an atom or group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, an alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted heteroaryl group, a halogen atom, a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted amino group, a nitro group, a cyano group, a substituted or unsubstituted silyl group, and a substituted or unsubstituted siloxy group. Among them, in the R 1 and R 2 group, the R 2 and R 3 group, the R 4 and R 5 group, the R 5 and R 6 group, in any one or more of these groups, a bond can be formed between the groups constituting the group to form a ring; Z 1 and Z 2 each independently is an atom or group selected from a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a cyano group, and a substituted or unsubstituted aryloxy group, wherein a bond can be formed between Z 1 and Z 2 to form a ring among all the above groups, when being substituted, the substituent is a group selected from an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an aralkyl group, a halogen, a cyano group, a formyl group, an acyl group having 2 to 40 carbon atoms, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxysulfonyl group, an aminosulfonyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boranyl group, a phosphinyl oxide group, and an oxo group.

5. The light-emitting element according to claim 4, in the general formula (2), In X 1 When it is carbon, the group bonded to the carbon is a group represented by the following general formula (3). wherein, R 9 to R 11 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a hydroxyl group, a mercapto group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a halogen atom, a cyano group, a formyl group, an acyl group having 2 to 40 carbon atoms, a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted alkylsulfonyl group, a substituted or unsubstituted arylsulfonyl group, a substituted or unsubstituted aminosulfonyl group, a substituted or unsubstituted amino group, a nitro group, a substituted or unsubstituted silyl group, and an atom or group in a ring structure formed with an adjacent group. R 7 and R 8 each independently is a group selected from substituted or unsubstituted alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; Z 1 and Z 2 each independently represents a group selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, substituted or unsubstituted aryl, halogen atom, and cyano group, R 1 、R 3 、R 4 and R 6 each independently is a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, Among them, these aryl and heteroaryl groups can be monocyclic or fused-ring; wherein in R 1 and R 6 when one or both of them are monocyclic aryl and heteroaryl groups, the monocyclic aryl and heteroaryl groups have more than 1 secondary alkyl group, more than 1 tertiary alkyl group, more than 1 aryl group or more than 1 heteroaryl group as substituents, or have a total of 2 or more methyl groups and primary alkyl groups as substituents; R 2 and R 5 each independently represents an atom or group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a halogen atom, a cyano group, a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted amino group, a nitro group, and a substituted or unsubstituted silyl group. Among them, R 4 and R 5 group, and R 2 and R 3 One or both of the groups can form a bond between the groups constituting the group to form a ring with more than five members. among all the above groups, when being substituted, the substituent is a group selected from an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an aralkyl group, a halogen, a cyano group, a formyl group, an acyl group having 2 to 40 carbon atoms, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxysulfonyl group, an aminosulfonyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boranyl group, a phosphinyl oxide group, and an oxo group.

6. The light-emitting element according to claim 4, in the general formula (2), In the case of X 1 when X is carbon, the group bonded to the carbon is a group represented by the following general formula (4), wherein, R 12 to R 14 each independently represents an atom or group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkenyl group, a substituted or unsubstituted alkynyl group, a hydroxyl group, a mercapto group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a halogen atom, a cyano group, a formyl group, an acyl group having 2 to 40 carbon atoms, a carboxyl group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted alkylsulfonyl group, a substituted or unsubstituted arylsulfonyl group, a substituted or unsubstituted alkoxysulfonyl group, a substituted or unsubstituted aminosulfonyl group, a substituted or unsubstituted amino group, a nitro group, a substituted or unsubstituted silyl group, a substituted or unsubstituted siloxy group, a substituted or unsubstituted boranyl group, and a substituted or unsubstituted phosphinyl group. R 15 is a group selected from substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclic group, substituted or unsubstituted alkenyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted alkynyl, hydroxyl group, mercapto group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, halogen atom, cyano group, formyl group, acyl group having 2 to 40 carbon atoms, carboxyl group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted alkylsulfonyl group, substituted or unsubstituted arylsulfonyl group, substituted or unsubstituted alkoxysulfonyl group, substituted or unsubstituted aminosulfonyl group, substituted or unsubstituted amino group, nitro group, substituted or unsubstituted silyl group, substituted or unsubstituted siloxy group, substituted or unsubstituted boranyl group, and substituted or unsubstituted phosphinyl group, Ar 1 is a group selected from substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl; Z 1 and Z 2 each independently represents an atom or group selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, substituted or unsubstituted aryl, halogen atom, and cyano group R 1 ~R 6 Each independently represents a group selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted amino group, a substituted or unsubstituted silyl group, and a substituted or unsubstituted siloxy group, wherein R 1 、R 3 、R 4 、R 6 at least one of them is a hydrogen atom, or a substituted or unsubstituted alkyl group. among all the above groups, when being substituted, the substituent is a group selected from an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, a heteroaryl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an aralkyl group, a halogen, a cyano group, a formyl group, an acyl group having 2 to 40 carbon atoms, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxysulfonyl group, an aminosulfonyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boranyl group, a phosphinyl oxide group, and an oxo group.

7. The light-emitting element according to any one of claims 3 to 6, wherein the light-emitting element has a charge generation layer, and the charge generation layer further contains an alkali metal or an alkali metal compound.

8. The light-emitting element according to claim 7, wherein the alkali metal element constituting the alkali metal or the alkali metal compound is lithium.

9. A display device comprising the light-emitting element according to any one of claims 3 to 8.

10. An illumination device comprising the light-emitting element according to any one of claims 3 to 8.

11. A method for producing a C-type crystal of the phenanthroline derivative according to claim 1 or 2, comprising the following steps: a step (I) of dissolving 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene, which is a phenanthroline derivative, in a mixed solvent containing an aprotic polar solvent and an aromatic solvent and crystallizing it; and then a step (III) of drying the crystal obtained through step (I) at 50 °C or higher.

12. A method for producing a C-type crystal of the phenanthroline derivative according to claim 1 or 2, comprising the following step: a step of subjecting an E-type crystal of 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene, which is a phenanthroline derivative and has peaks at diffraction angles 2θ of 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2, 20.0 ± 0.2, and 23.6 ± 0.2 in powder X-ray diffraction, to a polymorphic transformation. wherein, the unit of the diffraction angle 2θ is °.

13. The method for producing a C-type crystal of the phenanthroline derivative according to claim 12, wherein as the E-type crystal of 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene, which is a phenanthroline derivative and has peaks at diffraction angles 2θ of 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2, 20.0 ± 0.2, and 23.6 ± 0.2 in powder X-ray diffraction, a substance having an endothermic peak in the range of 94 to 98 °C in simultaneous differential thermal-thermogravimetric measurement is used. wherein, the unit of the diffraction angle 2θ is °.

14. The method for producing a C-type crystal of the phenanthroline derivative according to claim 12 or 13, by a step (I) of dissolving 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene, which is a phenanthroline derivative, in a mixed solvent containing an aprotic polar solvent and an aromatic solvent and crystallizing it, and then a step (IV) of drying the crystal obtained through step (I) at less than 50 °C, to produce an E-type crystal of 1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene, which is a phenanthroline derivative and has peaks at diffraction angles 2θ of 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2, 20.0 ± 0.2, and 23.6 ± 0.2 in powder X-ray diffraction. wherein, the unit of the diffraction angle 2θ is °.

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