WO2021193818A1

WO2021193818A1 - Crystal of phenanthroline derivative, method for producing same and light emitting element using same

Info

Publication number: WO2021193818A1
Application number: PCT/JP2021/012518
Authority: WO
Inventors: 杉本和則; 岡野翼; 藤田達也; 高橋弘純; 長尾和真; 川本一成; 徳田貴士; 星野秀尭; 野田大貴
Original assignee: 東レ株式会社
Priority date: 2020-03-26
Filing date: 2021-03-25
Publication date: 2021-09-30
Also published as: CN115335385A; KR20220157948A; JPWO2021193818A1

Abstract

The purpose of the present invention is to provide: a crystal of a phenanthroline derivative, said crystal having high chemical purity and low residual solvent content, thereby being suitable for use as a light emitting element material; and a method for producing this crystal of a phenanthroline derivative. The present invention provides: a crystal of a phenanthroline derivative, said crystal having a structure represented by general formula (1), while respectively 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 the powder X-ray diffraction pattern (said crystal being referred to as a B-form crystal); and crystal of a phenanthroline derivative, said crystal having a structure represented by general formula (1), while respectively 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 the powder X-ray diffraction pattern (said crystal being referred to as a C-form crystal). In addition, the present invention provides a crystal of a phenanthroline derivative, said crystal having a structure represented by general formula (1), while respectively 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 the powder X-ray diffraction pattern, said crystal being suitable for the achievement of a C-form crystal. (In the formula, X represents a phenylene group or a naphthylene group.)

Description

Crystals of phenanthroline derivatives, methods for producing them, and light emitting devices using them

The present invention relates to crystals of a phenanthroline derivative and a method for producing the same. The phenanthroline derivative is a compound useful as a light emitting element material that can be used in fields such as display elements, flat panel displays, backlights, lighting, interiors, signs, signboards, electronic cameras, and optical signal generators.

Regarding the phenanthroline derivative, for example, a material for a light emitting element including the phenanthroline derivative represented by the general formula (1) described later has been disclosed, and as a method for producing the phenanthroline derivative, 1,3-di (1,10) has been disclosed. -Phenanthroline-2-yl) Benzene is allowed to act on phenyllithium and then oxidized, or 1,3-dibromobenzene is reacted with t-butyllithium and then 2-phenyl-1,10-phenanthroline is allowed to act on it. Then, a method of oxidizing is disclosed (see, for example, Patent Document 1).

Further, as a method for producing a nitrogen-containing aromatic ring derivative including a phenanthroline derivative represented by the general formula (1) described later, a dibromoaromatic compound is dilithiated with n-butyllithium or sec-butyllithium, and then nitrogen-containing. A method of adding an aromatic ring derivative and then oxidizing it has been proposed (see, for example, Patent Document 2).

Further, regarding a polymer electrolyte composition containing an ionic group-containing polymer, an organic phosphorus-based additive, and a nitrogen-containing heteroaromatic ring-based additive, as a method for producing a nitrogen-containing heteroaromatic ring-based additive, 8- A method of reacting an amino-7-quinoline carboaldehyde with 1,3-diacetylbenzene and potassium hydroxide, then reacting with phenyllithium, and then oxidizing and recrystallizing is disclosed (for example, Patent Document). 3).

Japanese Unexamined Patent Publication No. 2004-281390 Japanese Unexamined Patent Publication No. 2008-189660 International Publication No. 2015/156228

Organic compounds generally have a plurality of solid states such as amorphous and crystalline. The same applies to phenanthroline derivatives, and crystalline polymorphs are present. Even if the crystal structure of the phenanthroline derivative is the same on a molecular basis, it affects the chemical and physical properties and handleability because the molecular packing mode is different. For example, when the above-mentioned phenanthroline compound is used as a light emitting element material, it is generally sublimated and purified, but Patent Document 1 does not disclose that its solid state can be specified, and is described in Patent Document 2. Since the phenanthroline derivative obtained by the conventional production method has a low chemical purity, there is a problem that the chemical purity is insufficient to be used as a light emitting element material even after sublimation purification. Further, although the crystal form cannot be specified from the production method disclosed in Patent Document 3, a solvate crystal is formed depending on the crystal form and a large amount of residual solvent is used, which causes bumping during sublimation purification. There was a problem.

Therefore, an object of the present invention is to provide crystals of a phenanthroline derivative having high chemical purity and a small amount of residual solvent, and a method for producing the same.

That is, the present invention has a structure represented by the general formula (1), and in powder X-ray diffraction, the diffraction angles 2θ (°) 6.7 ± 0.2, 8.2 ± 0.2, 13. It is a crystal of a phenanthroline derivative having peaks at 7 ± 0.2, 17.7 ± 0.2 and 22.2 ± 0.2, respectively. In addition, another aspect of the present invention has a structure represented by the general formula (1), and in powder X-ray diffraction, the diffraction angles are 2θ (°) 5.0 ± 0.2 and 7.5 ± 0. It is a crystal of a phenanthroline derivative having peaks at 2, 8.7 ± 0.2, 12.5 ± 0.2 and 17.3 ± 0.2, respectively. In addition, another aspect of the present invention has a structure represented by the general formula (1), and in powder X-ray diffraction, the diffraction angles are 2θ (°) 5.2 ± 0.2 and 7.0 ± 0. It is a crystal of a phenanthroline derivative having peaks at 2, 16.4 ± 0.2, 20.0 ± 0.2 and 23.6 ± 0.2, respectively, and this crystal is for obtaining a C-type crystal described later. It is extremely suitable as a crystal of.

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

The crystals of the phenanthroline derivative of the present invention have high chemical purity and a small amount of residual solvent. Therefore, there is an effect that bumping in sublimation purification can be suppressed. Further, it has an effect that it can be suitably used as a light emitting device material after sublimation purification by taking advantage of its high chemical purity. Further, when a specific pyrromethene compound is used in combination, the light emitting element can be driven at a low voltage when the light emitting element is manufactured.

FIG. 5 is a powder X-ray diffraction pattern of a B-type crystal of a phenanthroline derivative represented by the general formula (1) obtained in Example 1. It is a figure which shows the differential thermal analysis curve obtained by the differential thermogravimetric analysis simultaneous measurement of the B-type crystal of the phenanthroline derivative represented by the general formula (1) obtained by Example 1. FIG. It is a powder X-ray diffraction pattern of the C-type crystal of the phenanthroline derivative represented by the general formula (1) obtained by Example 3. FIG. It is a figure which shows the differential thermal analysis curve obtained by the differential thermogravimetric analysis simultaneous measurement of the C-type crystal of the phenanthroline derivative represented by the general formula (1) obtained by Example 3. FIG. 6 is a powder X-ray diffraction pattern of an E-type crystal of a phenanthroline derivative represented by the general formula (1) obtained in Example 6. It is a figure which shows the differential thermal analysis curve obtained by the differential thermogravimetric analysis simultaneous measurement of the E-type crystal of the phenanthroline derivative represented by the general formula (1) obtained by Example 6. FIG. FIG. 5 is a powder X-ray diffraction pattern of a D-type crystal of a phenanthroline derivative represented by the general formula (1) obtained in Comparative Example 1. It is a figure which shows the differential thermal analysis curve obtained by the differential thermogravimetric analysis simultaneous measurement of the D-type crystal of the phenanthroline derivative represented by the general formula (1) obtained by the comparative example 1. FIG. It is an amorphous powder X-ray diffraction pattern of the phenanthroline derivative represented by the general formula (1) obtained by Comparative Example 2.

Hereinafter, the present invention will be described in detail. The inventions according to claims 1 to 3 in the claims are inventions of C-type crystals of a phenanthroline derivative. On the other hand, the invention according to claim 16 is an invention of an E-type crystal of a phenanthroline derivative. Further, the inventions according to claims 17 to 19 are inventions of B-type crystals of a phenanthroline derivative. The inventions according to claims 12 to 15 are inventions of a production method for producing a C-type crystal from an E-type crystal. The invention according to claim 20 is an invention of a production method for producing a B-shaped crystal.

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 in powder X-ray diffraction, the diffraction angle is 2θ (°) 6.7 ± 0.2, 8. It has a specific crystalline form with peaks at 2 ± 0.2, 13.7 ± 0.2, 17.7 ± 0.2 and 22.2 ± 0.2, respectively, as used herein. Is referred to as a B-shaped crystal.

Further, 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 in powder X-ray diffraction, a diffraction angle of 2θ (°) 5.0 ± 0.2, It has a specific crystalline form with peaks at 7.5 ± 0.2, 8.7 ± 0.2, 12.5 ± 0.2 and 17.3 ± 0.2, respectively, and is described herein. In the book, it is called a C-shaped crystal.

B-type crystals and C-type crystals of phenanthroline derivatives have high chemical purity and a small amount of residual solvent, so that bumping in sublimation purification can be suppressed. Further, taking advantage of its high chemical purity, it can be suitably used as a light emitting device material after sublimation purification.

In the above general formula (1), X represents a phenylene group or a naphthylene group. Of these, a phenylene group is preferable from the viewpoint of molecular weight and sublimation purification temperature.

Examples of the phenanthroline derivative represented by the general formula (1) include those having the following structure.

Among these, 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene is preferable from the viewpoint of ease of synthesis and stability of the thin film.

Among the crystals of the phenanthroline derivative of the present invention, the crystals shown as B-type crystals have diffraction angles of 2θ (°) 6.7 ± 0.2, 8.2 ± 0.2, 13.7 ± 0 in powder X-ray diffraction. Crystals having peaks at .2, 17.7 ± 0.2 and 22.2 ± 0.2, respectively, and the crystals shown as C-type crystals have diffraction angles of 2θ (°) 5.0 ± 0.2, 7 It is a crystal having peaks at 5.5 ± 0.2, 8.7 ± 0.2, 12.5 ± 0.2 and 17.3 ± 0.2, respectively.

Here, the powder X-ray diffraction can be measured under the following conditions using a powder X-ray diffractometer. The measurement sample is prepared by filling a sample plate (material: silicon; depth: 0.2 mm) with the sample and flattening the sample surface.
X-ray source: CuKα ray * Curved crystal monochromator (graphite) is used Output: 40kV / 50mA
Divergence slit: 1/2 °
Divergence vertical restriction slit: 5 mm
Scattering slit: 1/2 °
Light receiving slit: 0.15 mm
Detector: Scintillation counter Scan method: 2θ / θ scan, continuous scan Measurement range (2θ): 2 to 30 °
Scan speed (2θ): 20 ° / min
Counting step (2θ): 0.04 °.

The B-type crystal of the phenanthroline derivative of the present invention preferably has an endothermic peak in the range of 180 to 184 ° C. in the differential thermal weight simultaneous measurement (hereinafter, may be abbreviated as "TG-DTA"). Such an endothermic peak is one of the characteristics for specifying the crystal form, and having an endothermic peak in the range of 180 to 184 ° C. means that it is the above-mentioned B-type crystal. Further, the C-type crystal of the phenanthroline derivative of the present invention preferably has an endothermic peak in the range of 243 to 247 ° C. in the simultaneous measurement of differential thermogravimetric analysis. Having an endothermic peak in the range of 243 to 247 ° C. means that it is the above-mentioned C-type crystal.

Here, TG-DTA can be measured under the following conditions using a TG-DTA device, and the temperature at the peak top indicated by the DTA curve is set as the endothermic peak.
Temperature rise rate: 5 ° C / min Atmosphere: Dry nitrogen (flow rate: 100 mL / min)
Sample cell: Aluminum open cell Sample amount: 5 to 15 mg.

The phenanthroline derivative represented by the general formula (1) can be produced, for example, by the method described in JP-A-2008-189660. That is, the desired phenanthroline derivative can be obtained by dilythiolating the dibromobenzene derivative with alkyllithium, allowing 2-phenyl-1,10-phenanthroline to act on the derivative, and then oxidizing the derivative.

The B-type crystal of the phenanthroline derivative represented by the general formula (1) of the first aspect of the present invention is, for example, an arbitrary form of the phenanthroline derivative represented by the general formula (1), an aprotic polar solvent and an aprotic polar solvent. Obtained by a method having a step (I) of dissolving and crystallizing in a mixed solvent containing an aromatic solvent, and then a step (II) of dissolving and crystallizing the crystals obtained in step (I) in an ether solvent. be able to.

Examples of the aprotonic polar solvent include amide-based solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone; sulfoxide-based solvents such as dimethylsulfoxide; , 3-Dimethyl-2-imidazolidinone, N, N-dimethylpropylene urea and other urea solvents; acetonitrile, propionitrile and other nitrile solvents; pyridine, 2-methylpyridine and other pyridine solvents and the like. .. Two or more of these may be used. Among these, an amide solvent, a sulfoxide solvent, and a urea solvent are preferable, and 1,3-dimethyl-2-imidazolidinone is more preferable from the viewpoint of improving the recovery rate of B-type crystals.

Examples of the aromatic solvent include benzene, chlorobenzene, anisole, toluene, xylene, cumene, mesitylene and the like. Two or more of these may be used. Among these, anisole, toluene and xylene are preferable, and toluene is more preferable from the viewpoint of improving the recovery rate of B-type crystals.

In the mixed solvent containing the aprotic polar solvent and the aromatic solvent, the content of the aromatic solvent is 50 with respect to 100 parts by weight of the aprotic polar solvent from the viewpoint of improving the recovery rate of the B-type crystal. It is preferably up to 500 parts by weight, more preferably 100 to 300 parts by weight.

Further, in the mixed solvent containing the aprotic polar solvent and the aromatic solvent, the solvents other than the aprotic polar solvent and the aromatic solvent are mixed as long as the crystals of the phenanthroline derivative having the desired diffraction angle can be obtained. It may be contained in a solvent.

The amount of the mixed solvent used is preferably 300 parts by weight or more, more preferably 500 parts by weight or more, based on 100 parts by weight of the phenanthroline derivative represented by the general formula (1), from the viewpoint of facilitating stirring. On the other hand, the amount of the mixed solvent used is preferably 10,000 parts by weight or less, preferably 10,000 parts by weight or less, based on 100 parts by weight of the phenanthroline derivative represented by the general formula (1), from the viewpoint of improving the production efficiency per unit volume. More preferably, it is 000 parts by weight or less.

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

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

When it is heated and melted in the step (I), it is preferable to cool it in the step of crystallization. The cooling temperature is preferably −20 to 30 ° C., more preferably −10 to 10 ° C. from the viewpoint of improving the recovery rate of B-type crystals. The cooling rate is preferably 0.1 to 50 hours, more preferably 0.5 to 20 hours. While cooling, it may be agitated or allowed to stand.

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-methyl tetrahydrofuran, 1,4-dioxane and the like. Cyclic ethers and the like can be mentioned. Two or more of these may be used. Among these, cyclic ethers are preferable, and tetrahydrofuran is more preferable from the viewpoint of improving the recovery rate of B-type crystals.

The amount of the ether solvent used is preferably 300 parts by weight or more, more preferably 500 parts by weight or more, based on 100 parts by weight of the phenanthroline derivative represented by the general formula (1), from the viewpoint of facilitating stirring. On the other hand, the amount of the ether solvent used is preferably 10,000 parts by weight or less with respect to 100 parts by weight of the phenanthroline derivative represented by the general formula (1) from the viewpoint of improving the production efficiency per unit volume. More preferably, it is 000 parts by weight or less.

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

When heating and melting in step (II), it is preferable to cool in the step of crystallization. The preferred ranges of cooling temperature and cooling rate are the same as in step (I).

In the step of crystallization in step (II), the B-type crystal of the phenanthroline derivative obtained in advance may be added as a seed crystal. Further, it may further have a step of drying the obtained crystals.

The C-type crystal of the phenanthroline derivative represented by the general formula (1) of the second aspect of the present invention is, for example, an arbitrary form of the phenanthroline derivative represented by the general formula (1), an aprotic polar solvent and an aprotic polar solvent. It can be obtained by a method having a step (I) of dissolving and crystallizing in a mixed solvent containing an aromatic solvent, and then a step (III) of drying the crystals obtained in the step (I) at 50 ° C. or higher.

Examples of the aprotic polar solvent include those exemplified in the method for producing a B-type crystal according to the first aspect. Of these, amide-based solvents, sulfoxide-based solvents, and urea-based solvents are preferable, and from the viewpoint of improving the recovery rate of C-type crystals, 1,3-dimethyl-2-imidazolidinone, N-methylpyrrolidone, N, N -Dimethylacetamide is more preferred.

Examples of the aromatic solvent include those exemplified in the method for producing a B-shaped crystal according to the first aspect. Among these, anisole, toluene, and xylene are preferable, and anisole is more preferable from the viewpoint of improving the recovery rate of C-type crystals.

In the mixed solvent containing the aprotic polar solvent and the aromatic solvent, the content of the aromatic solvent is 50 with respect to 100 parts by weight of the aprotic polar solvent from the viewpoint of improving the recovery rate of the C-shaped crystal. It is preferably up to 210 parts by weight, more preferably 100 to 205 parts by weight.

Further, even in the mixed solvent containing the aprotic polar solvent and the aromatic solvent used here, crystals of the phenanthroline derivative having the desired diffraction angle can be obtained as the solvent other than the aprotic polar solvent and the aromatic solvent. It may be contained in the mixed solvent as long as possible.

In the step (I), as a method for 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 the step (I) in the method for producing a B-shaped crystal according to the first aspect.

When it is melted by heating in the step (I), it is preferable to cool it in the step of crystallization. The preferable ranges of the cooling temperature and the cooling rate are the same as those in the step (I) in the method for producing a B-shaped crystal according to the first aspect.

The drying temperature in the step (III) is preferably 50 ° C. or higher, more preferably 80 ° C. or higher, from the viewpoint of efficiently performing the crystal polymorphic transition. On the other hand, the drying temperature is preferably 150 ° C. or lower, more preferably 130 ° C. or lower, from an industrial point of view. Further, the drying in the step (III) is preferably vacuum drying. The degree of pressure reduction for vacuum drying is preferably 666.6 Pa (5 mmHg) or less from the viewpoint of quickly removing the residual solvent.

Further, the C-type crystal of the phenanthroline derivative represented by the general formula (1) has, for example, the structure represented by the general formula (1), and in powder X-ray diffraction, the diffraction angle is 2θ (°) 5. Crystals of phenanthroline derivatives with peaks at 2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2, 20.0 ± 0.2 and 23.6 ± 0.2, respectively. It can also be obtained by crystal polymorphic transition (referred to as E-type crystal in the specification). The C-type crystal of the phenanthroline derivative represented by the general formula (1) can also be obtained by heating a crystal other than the C-type crystal and drying it to promote the crystal polymorphic transition, but the temperature is high. It varies greatly depending on the crystal form. Among the crystal forms, the E-type crystal is preferable from an industrial point of view because the crystal polymorphic transition proceeds at a relatively low temperature and a C-type crystal can be obtained. In this case, it is preferable to obtain an E-type crystal in the above-mentioned step (I) and to obtain a C-type crystal by crystal polymorph transition in the above-mentioned step (III).

The E-type crystal of the phenanthroline derivative is effective as a precursor of the C-type crystal because it easily transforms 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 the simultaneous measurement of differential thermogravimetric analysis, and having an endothermic peak in such a temperature range means that it is an E-type crystal. means. The powder X-ray diffraction measurement and the differential thermogravimetric simultaneous measurement can be performed by the same method as described for the B-type crystal and the C-type crystal described above.

The E-type crystal of the phenanthroline derivative represented by the general formula (1) is, for example, a mixed solvent containing an arbitrary form of the phenanthroline derivative represented by the general formula (1), an aprotonic polar solvent and an aromatic solvent. It can be obtained by a method having a step (I) of dissolving and crystallizing in a solvent, and then a step (IV) of drying the crystals obtained in the step (I) at a temperature lower than 50 ° C.

Further, even in the mixed solvent containing the aprotic polar solvent and the aromatic solvent used here, crystals of a phenanthroline derivative having a desired diffraction angle can be obtained as a solvent other than the aprotic polar solvent and the aromatic solvent. As long as it is contained in the mixed solvent, it may be contained.

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

By transferring the E-type crystal of the phenanthroline derivative represented by the general formula (1) obtained by the above method to a polymorphic crystal, a C-type crystal can be efficiently obtained. As the step of transferring the crystal polymorph, 50 ° C. or higher is preferable, and 80 ° C. or higher is more preferable. On the other hand, since the crystal polymorphic transition of the E-type crystal proceeds at a relatively low temperature, the temperature is preferably 150 ° C. or lower, more preferably 130 ° C. or lower, from an industrial point of view.

The B-type crystal or C-type crystal of the phenanthroline derivative represented by the general formula (1) of the present invention has a small amount of residual solvent and has extremely high chemical purity, so that it can be suitably used as a light emitting element material. 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, it is particularly suitable for the electron transport layer, the electron injection layer, and the charge generation layer among the light emitting elements. Can be used for. Then, the light emitting element of the present invention containing the phenanthroline derivative derived from the B-type crystal or the C-type crystal of the phenanthroline derivative of the present invention in the electron transport layer, the electron injection layer or the charge generation layer is made of the B-type crystal or the C-type crystal. Since the realized phenanthroline derivative has a layer having an extremely high chemical purity of 99.7% or more, the electron transport layer, the electron injection layer or the charge generation layer is made into a stable layer with little change in film quality over time. Moreover, even when a heat-activated delayed fluorescent material is used for the light emitting layer, it is possible to exhibit an external quantum efficiency of 7.0% or more.

Further, since the B-type crystal or C-type crystal of the phenanthroline derivative of the present invention has a small amount of residual solvent and extremely high chemical purity, the amount of degassing when producing a luminous element is small, and a high-purity film can be formed. Therefore, a light emitting element having high luminous efficiency can be obtained. In particular, since the driving voltage is reduced and high-efficiency light emission can be obtained, it is suitably used for a light emitting device containing a thermally activated delayed fluorescent material (sometimes referred to as "TADF material") in the light emitting layer.

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

The light emitting element of the present invention has a function of converting electrical energy into light. Here, direct current is mainly used as electrical energy, but pulse current and alternating current can also be used. The current value and the voltage value are not particularly limited, and the characteristic values required differ depending on the purpose of the device, but it is preferable to obtain high brightness at a low voltage from the viewpoint of power consumption and life of the device. Further, from the viewpoint of increasing the color purity, the half width of the emission spectrum 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. preferable. Since the light emitting device of the present invention has a narrow half width of the light emitting spectrum, it is more preferable to use it as a top emission type light emitting device. Due to the resonance effect of the microcavity, the top emission type light emitting element has higher luminous efficiency as the half width is narrower. Therefore, it is possible to achieve both high color purity and high luminous efficiency.

The light emitting element of the present invention is suitably used, for example, as a display device application such as a display in which a matrix method, a segment method, or both types are used in combination. It is also preferably used as a backlight for various devices. The backlight is mainly used for the purpose of improving the visibility of display devices such as displays that do not emit light by itself, and is used for display devices such as liquid crystal displays, clocks, audio devices, automobile panels, display boards and signs. In particular, the light emitting element of the present invention is preferably used for a liquid crystal display, particularly a backlight for a personal computer whose thinness is being studied, and can provide a backlight thinner and lighter than the conventional one. The light emitting element of the present invention is also preferably used as various lighting devices. It is possible to achieve both high luminous efficiency and high color purity, and because it is possible to make it thinner and lighter, it is possible to realize a lighting device that combines low power consumption, vivid emission color, and high design. ..

The light emitting device of the present invention has, for example, a structure having an anode and a cathode, and an organic layer between the anode and the cathode. The organic layer preferably includes at least a light emitting layer, and the light emitting layer is an organic electroluminescent device that emits light by electric energy. The light emitting element may be either a bottom emission type or a top emission type. In such a light emitting element, the layer structure of the organic layer between the anode and the cathode is not only composed of the light emitting layer but also 1) light emitting layer / electron transporting layer, 2) hole transporting layer / light emitting layer, and 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) Examples thereof include a laminated structure such as a hole injection layer / a hole transport layer / an electron blocking layer / a light emitting layer / a hole blocking layer / an electron transport layer / an electron injection layer.

Further, a tandem type light emitting element in which a plurality of the above laminated configurations are laminated via an intermediate layer may be used. Examples of the intermediate layer generally include an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, an intermediate insulation layer, and the like, and known material configurations can be used. Preferred specific examples of the tandem type light emitting element are 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 / A laminated structure such as an electron transport layer / electron injection layer can be mentioned. Further, each of the above layers may be either a single layer or a plurality of layers, and may be doped. Further, there is also an element configuration including a layer using a capping material for improving the luminous efficiency due to the optical interference effect.

The electron transport layer is a layer in which electrons are injected from the cathode and further electrons are transported. The electron transport material used for the electron transport layer is required to have a high electron affinity, a high electron mobility, excellent stability, and a substance in which impurities that serve as traps are unlikely to be generated. Further, a compound having a molecular weight of 400 or more is preferable because a compound having a low molecular weight tends to crystallize and deteriorate the film quality. The electron transport layer in the present invention also includes a hole blocking layer capable of efficiently blocking the movement of holes as a synonym. The hole blocking layer and the electron transporting layer may be formed alone or by laminating a plurality of materials. Examples of the electron transporting material include polycyclic aromatic derivatives, styryl-based aromatic ring derivatives, quinone derivatives, phosphoroxide derivatives, quinolinol complexes such as tris (8-quinolinolate) aluminum (III), benzoquinolinol complexes, hydroxyazole complexes, and azomethine complexes. , Tropolone metal complexes and various metal complexes such as flavonol metal complexes.

It is preferable to use a compound having a heteroaryl group containing electron-accepting nitrogen because the driving voltage can be reduced and high-efficiency light emission can be obtained. Here, the electron-accepting nitrogen represents a nitrogen atom forming a multiple bond with an adjacent atom. Since the heteroaryl group containing electron-accepting nitrogen has a large electron affinity, it becomes easy for electrons to be injected from the cathode, and a lower voltage drive becomes possible. In addition, the supply of electrons to the light emitting layer is increased, and the recombination probability is increased, so that the luminous efficiency is improved. Examples of the compound having a heteroaryl group structure containing electron-accepting nitrogen include a pyridine derivative, a triazine derivative, a pyrazine derivative, a pyrimidine derivative, a quinoline derivative, a quinoxaline derivative, a quinazoline derivative, a naphthylidine derivative, a benzoquinoline derivative, a phenanthroline derivative, and an imidazole. Preferred compounds include derivatives, oxazole derivatives, thiazole derivatives, triazole derivatives, oxaziazole derivatives, thiadiazol derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, phenanthle midazole derivatives, and oligopyridine derivatives such as bipyridine and tarpyridine. Is listed as.

Among them, imidazole derivatives such as tris (N-phenylbenzimidazole-2-yl) benzene, and oxadiazole derivatives such as 1,3-bis [(4-tert-butylphenyl) -1,3,4-oxadiazolyl] phenylene. Triazole derivatives such as N-naphthyl-2,5-diphenyl-1,3,4-triazole; phenanthroline derivatives such as vasocproin and 1,3-bis (1,10-phenanthroline-9-yl) benzene; 2,2 Benzene (benzo [h] quinoline-2-yl) -9,9'-benzoquinoline derivatives such as spirobifluorene; 2,5-bis (6'-(2', 2 "-bipyridyl))-1 , 1-Dimethyl-3,4-diphenylsilol and other bipyridine derivatives; 1,3-bis (4'-(2,2': 6'2 "-terpyridinyl)) benzene and other terpyridine derivatives; bis (1-naphthyl) ) -4- (1,8-naphthylidine-2-yl) naphthylidine derivatives such as phenylphosphine oxide and triazine derivatives are preferably used from the viewpoint of electron transport ability. Further, it is more preferable that the electron transport material has a condensed polycyclic aromatic skeleton because the glass transition temperature is improved, the electron mobility is large, and the voltage can be lowered.

As such a condensed polycyclic aromatic skeleton, a fluoranthene skeleton, an anthracene skeleton, a pyrene skeleton or a phenanthroline skeleton is preferable, and a fluoranthene skeleton or a phenanthroline skeleton is particularly preferable. The electron transport material may be used alone or in combination of two or more. Further, the electron transport layer may contain a donor material. Here, the donor material is a compound that facilitates electron injection from the cathode or the electron injection layer into the electron transport layer by improving the electron injection barrier, and further improves the electrical conductivity of the electron transport layer. Preferred examples of donor materials include alkali metals such as lithium, inorganic salts containing alkali metals such as lithium fluoride, complexes of alkali metals such as lithium quinolinol and organic substances, alkaline earth metals, and alkaline earth metals. Examples thereof include inorganic salts contained, complexes of alkaline earth metals and organic substances, rare earth metals such as europium and itterbium, inorganic salts containing rare earth metals, and complexes of rare earth metals and organic substances. As the donor material, metallic lithium, rare earth metal, or lithium quinolinol (Liq) is particularly preferable.

The electron injection layer is formed for the purpose of assisting the injection of electrons from the cathode to the electron transport layer, and is composed of a compound having a heteroaryl ring structure containing electron-accepting nitrogen and the above-mentioned donor material. Further, an insulator or a semiconductor inorganic substance can be used for the electron injection layer. It is preferable to use these materials because it is possible to prevent a short circuit of the light emitting element and improve the electron injection property. As such an insulator, it is preferable to use at least one metal compound selected from the group consisting of alkali metal chalcogenides, alkaline earth metal chalcogenides, alkali metal halides and alkaline earth metal halides.

The charge generation layer is a layer that generates or separates charges by applying a voltage and injects charges into adjacent layers. The charge generation layer may be formed of one layer, or a plurality of layers may be laminated. Generally, a layer that easily generates electrons as an electric charge 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 double layer, 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 pn junction type charge generation layer, an electric charge is generated by applying a voltage in a light emitting element, or the charge is separated into holes and electrons, and these holes and electrons are separated into a hole transport layer and an electron transport layer. Is injected into the light emitting layer via. Specifically, in a light emitting device including a plurality of light emitting layers, when a charge generating layer is used as an intermediate layer, the n-type charge generating layer supplies electrons to the first light emitting layer existing on the anode side to supply p-type charges. The generation layer supplies holes to the second light emitting layer existing on the cathode side.

Therefore, in a light emitting device having two or more light emitting layers, by having one or more charge generating layers between the light emitting layers, it is possible to further improve the element efficiency and reduce the driving voltage. The durability of the element can be further improved. The n-type charge generation layer consists of an n-type dopant and an n-type host, and conventional materials can be used for these. For example, as the n-type dopant, the donor material exemplified as the material of the electron transport layer is preferably used. Among these, alkali metals or salts thereof and rare earth metals are preferable, and materials selected from metallic lithium, lithium fluoride (LiF), lithium quinolinol (Liq) and metallic ytterbium are more preferable. Further, as the n-type host, those exemplified as the electron transport material are preferably used. Among these, a material selected from a triazine derivative, a phenanthroline derivative and an oligopyridine derivative is preferable, and a phenanthroline derivative or a terpyridine derivative is more preferable.

The p-type charge generation layer is composed of a p-type dopant and a p-type host, and conventional materials can be used for these. For example, as the p-type dopant, the acceptor material exemplified as the material of the hole injection layer, iodine, FeCl ₃ , FeF ₃ , SbCl _{5, and the} like are preferably used. Specific examples thereof include HAT-CN6, F4-TCNQ, tetracyanoquinodimethane derivative, radialene derivative, iodine, FeCl ₃ , FeF ₃ , SbCl _{5 and the} like. Among these, HAT-CN6 and (2E, 2'E, 2''E) -2,2', 2''- (cyclopropane-1,2,3-triylidene) tris (2- (perfluorophenyl) )-Utrigate), (2E, 2'E, 2''E) -2,2', 2''- (cyclopropane-1,2,3-triylidene) tris (2- (4-cyanoperfluorophenyl) -Radialene derivatives such as acetonitrile) are more preferred. A thin film of the p-type dopant may be formed, and the film thickness is preferably 10 nm or less. Further, an arylamine derivative is preferable as the p-type host.

The crystal of the phenanthroline derivative of the present invention can be used for an electron transport layer, an electron injection layer, and a charge generation layer, and when used for an electron transport layer, for example, a thickness composed of a host material, a dopant material, and a TADF material. It is preferable to use a vapor-deposited film having a thickness of several tens of nm, which is formed by forming a light emitting layer having a thickness of several tens of nm and laminating on the light emitting layer. The light emitting device thus produced exhibits very high external quantum efficiency.

When the crystal of the phenanthroline derivative of the present invention is used for the electron injection layer, for example, it is preferable to use it in a co-deposited film having a thickness of several nm containing an alkali metal as a donor material, and the same as above. It is preferable that the light emitting layer and the electron transporting layer of the above are sequentially laminated and formed on the electron transporting layer. The light emitting device thus produced also exhibits very high external quantum efficiency.

When the crystal of the phenanthroline derivative of the present invention is used for the charge generation layer, for example, it is used as the n-type host material of the n-type charge generation layer of the tandem type fluorescent light emitting device containing an alkali metal which is an n-type dopant. It is preferable that the same light emitting layer and the electron transporting layer are sequentially laminated and formed on the electron transporting layer. The light emitting device thus produced also exhibits very high external quantum efficiency.

The anode is an electrode formed on the substrate and is not particularly limited as long as it is a material capable of efficiently injecting holes into the organic layer. However, in a bottom emission type device, a transparent or translucent electrode is preferable, and top emission is preferable. In the type element, a reflective electrode is preferable. Materials for the transparent or translucent electrode include conductive metal oxides such as zinc oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO); or gold, silver, aluminum, chromium and the like. Metals; conductive polymers such as polythiophene, polypyrrole, polyaniline are exemplified. However, when a metal is used, it is preferable to reduce the film thickness so that light can be semi-transmitted.

Of the above, indium tin oxide (ITO) is more preferable from the viewpoint of transparency and stability. As the material of the reflective electrode, a material that does not absorb all light and has a high reflectance is preferable. Specifically, metals such as aluminum, silver, and platinum are exemplified. As the method for forming the anode, an optimum method can be adopted depending on the material for forming the anode, and examples thereof include a sputtering method, a vapor deposition method, and an inkjet method. For example, a sputtering method is used when an anode is formed of a metal oxide, and a thin-film deposition method is used when an anode is formed of a metal. The film thickness of the anode is not particularly limited, but is preferably several nm to several hundred nm. Further, these electrode materials may be used alone, or a plurality of materials may be laminated or mixed. Various wirings, circuits, and switching elements may be interposed between the substrate and the anode.

The cathode is an electrode formed on the surface opposite to the anode with the organic layer sandwiched between them, 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 can efficiently inject electrons into the light emitting layer, but it is preferably a reflective electrode for a bottom emission type element and a translucent electrode for a top emission type element. Is preferable.

Metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium are generally used as cathode materials; these metals are combined with low work function metals such as lithium, sodium, potassium, calcium and magnesium. Alloys and multilayer laminated films; or conductive metal oxides such as zinc oxide, tin indium oxide (ITO), and indium zinc oxide (IZO) are preferable. Among them, a metal selected from aluminum, silver and magnesium as a main component is preferable from the viewpoints of electric resistance value, ease of film formation, film stability, luminous efficiency and the like.

Further, when the cathode is composed of magnesium and silver, electron injection into the electron transport layer and the electron injection layer in the present invention becomes easy, and low voltage drive becomes possible, which is preferable. A protective layer (cap layer) may be laminated on the cathode to protect the cathode. The material constituting the protective layer is not particularly limited, but for example, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium; alloys using these metals; silica, titania, silicon nitride and the like. Inorganic substances: Organic polymer compounds such as polyvinyl alcohol, polyvinyl chloride, and hydrocarbon-based polymer compounds can be mentioned. However, when the light emitting element has an element structure (top emission structure) that extracts light from the cathode side, the material used for the protective layer is selected from materials having light transmission in the visible light region.

The light emitting layer is a layer that emits light by 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 viewpoint of color purity and light emission intensity, a host compound (hereinafter, may be referred to as “first compound”) and a dopant compound (hereinafter, “second compound”). It is preferable that it is composed of two or more kinds of materials (sometimes referred to as "compound of"). As the first compound, a thermally activated delayed fluorescent compound is a preferable example of the thermally activated delayed fluorescent material. Thermally activated delayed fluorescent compounds, also commonly referred to as TADF materials, are singlet from triplet excited state by reducing the energy gap between the singlet excited state energy level and the triplet excited state energy level. It is a material that promotes inverse intersystem crossing to the term excited state and improves the generation probability of singlet excited states. The difference between the lowest excited singlet energy level and the lowest excited triplet energy level (referred to as ΔEST) in the TADF material is preferably 0.3 eV or less. By utilizing delayed fluorescence by this thermal activated delayed fluorescence mechanism, the theoretical internal efficiency can be increased up to 100%.

Furthermore, when Felster-type energy transfer occurs from the singlet exciton of the first compound having thermal activated delayed fluorescence to the singlet exciton of the second compound, the singlet exciton of the second compound Fluorescent emission is observed. In order for such energy transfer to occur, it is preferable that the lowest excited singlet energy level of the first compound is larger than the lowest excited singlet energy level of the second compound. Here, when the second compound is a fluorescent light emitting material having a sharp light emitting spectrum, a light emitting element having high efficiency and high color purity can be obtained. As described above, when the light emitting layer contains a thermally activated delayed fluorescent compound, high-efficiency light emission is possible, which contributes to low power consumption of the display. The Thermally Activated Delayed Fluorescence Compound may be a compound that exhibits Thermally Activated Delayed Fluorescence with a Single Material, or exhibits Thermally Activated Delayed Fluorescence with a plurality of compounds as in the case of forming an exciplex complex. It may be a compound.

As the thermally activated delayed fluorescent compound, a single compound or a plurality of compounds may be mixed and used, and known materials can be used. Specific examples thereof include benzonitrile derivatives, triazine derivatives, disulfoxide derivatives, carbazole derivatives, indolocarbazole derivatives, dihydrophenazine derivatives, thiazole derivatives, oxadiazole derivatives and the like. In particular, a compound having an electron donating part (donor part) and an electron attracting part (acceptor part) in the same molecule is preferable.

Further, the light emitting layer of the light emitting element may contain a pyrromethene boron complex represented by the following general formula (2). In particular, when the first compound is a thermally activated delayed fluorescent compound, it is preferable that the second compound is a pyrometheneboron complex. The pyrromethene boron complex is a useful light emitting material that can obtain a sharp emission spectrum when used as a dopant, but it is necessary to achieve a light emitting element having high luminous efficiency and high durability while maintaining a sharp emission spectrum. Was difficult. However, the pyrromethene boron complex represented by the following general formula (2) can provide a light emitting material having a high fluorescence quantum yield and a sharp emission spectrum, and a light emitting element having high luminous efficiency, color purity and durability. ..

Here, in the above general formula (2), X ¹ is a nitrogen atom or a carbon atom, where the carbon atom includes a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted cycloalkyl. A 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. , Substituted or unsubstituted aralkyl group, substituted or unsubstituted heteroaryl group, halogen atom, carboxy group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted amino group, nitro One atomic or monovalent group selected from the group consisting of a group, a cyano group, a substituted or unsubstituted silyl group, and a substituted or unsubstituted siloxanyl group is bonded.

R ¹ to R ⁶ are independently hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted aryl group, alkoxy group, substituted or unsubstituted alkylthio group, respectively. Substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aralkyl group, substituted or unsubstituted heteroaryl group, halogen atom, carboxy group, substituted or Select from the group consisting of an 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 siroxanyl group. An atom or group to be formed, provided that in any one or more of ^{the R 1} and R ² pairs, the R ² and R ³ pairs, the R ⁴ and R ⁵ pairs, and the R ⁵ and R ^{6 pairs.} A ring may be formed by forming a bond between the groups constituting the set. Z ¹ and Z ² are independently halogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups, substituted or unsubstituted alkoxy groups, cyano groups, and substituted or unsubstituted aryloxy groups, respectively. It is an atom or group selected from the group consisting of, but may be a ring formed by forming a bond between ^{Z 1} and Z ^2.

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

Further, in all the above groups, the substituents in the case of substitution include 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 and a thiol. Group, alkoxy group, alkylthio group, aryloxy group, arylthio group, aralkyl group, halogen, cyano group, formyl group, acyl group, carboxy group, alkoxycarbonyl group, carbamoyl group, acyl group, alkylsulfonyl group, arylsulfonyl group, A group selected from the group consisting of an alkoxysulfonyl group, an aminosulfonyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, a phosphine oxide group and an oxo group is preferable. Furthermore, specific substituents that are preferable in the description of each substituent described later are more preferable. Further, these substituents may be further substituted with the above-mentioned substituents.

In the explanation of this explanation, "unsubstituted" means that the atom bonded to the target basic skeleton or group is only a hydrogen atom or a deuterium atom. The same applies to the case of "substitutable or unsubstituted" in the compound described below or its partial structure.

The alkyl group refers to a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group and a tert-butyl group, which are substituted. It may be non-replaceable. The additional substituent when substituted is not particularly limited, and examples thereof include an alkyl group, a halogen, an aryl group, and a heteroaryl group, and this point is also common to the following description. The number of carbon atoms of the alkyl group is not particularly limited, but is preferably 1 or more and 20 or less, and more preferably 1 or more and 8 or less from the viewpoint of availability and cost.

The cycloalkyl group refers to a saturated alicyclic hydrocarbon group such as a cyclopropyl group, a cyclohexyl group, a norbornyl group, or an adamantyl group, which may be substituted or unsubstituted. The number of carbon atoms in the alkyl group moiety is not particularly limited, but is preferably in the range of 3 or more and 20 or less.

The heterocyclic group refers to an aliphatic ring having an atom other than carbon such as a pyran ring, a piperidine ring, and a cyclic amide in the ring, which may be substituted or unsubstituted. The number of carbon atoms of the heterocyclic group is not particularly limited, but is preferably in the range of 2 or more and 20 or less.

The alkenyl group refers to an unsaturated aliphatic hydrocarbon group containing a double bond such as a vinyl group, an allyl group, or a butadienyl group, which may be substituted or unsubstituted. The carbon number of the alkenyl group is not particularly limited, but is preferably in the range of 2 or more and 20 or less.

The cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond such as a cyclopentenyl group, a cyclopentadienyl group, a cyclohexenyl group, etc., which may be substituted or unsubstituted. .. The number of carbon atoms of the cycloalkenyl group is not particularly limited, but is preferably in the range of 3 or more and 20 or less.

The alkynyl group refers to an unsaturated aliphatic hydrocarbon group containing a triple bond such as an ethynyl group, which may be substituted or unsubstituted. The number of carbon atoms of the alkynyl group is not particularly limited, but is preferably in the range of 2 or more and 20 or less.

The alkoxy group refers to a functional group in which an aliphatic hydrocarbon group is bonded via an ether bond such as a methoxy group, an ethoxy group, or a propoxy group, and the aliphatic hydrocarbon group may be substituted or unsubstituted. good. The number of carbon atoms of the alkoxy group is not particularly limited, but is preferably in the range of 1 or more and 20 or less.

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

The aryloxy group refers to a functional group in which an aromatic hydrocarbon group is bonded via an ether bond, such as a phenoxy group, and the aromatic hydrocarbon group may be substituted or unsubstituted. The number of carbon atoms of the aryloxy group is not particularly limited, but is preferably in the range of 6 or more and 40 or less.

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

The aralkyl group is an alkyl group in which one of the hydrogen atoms of the alkyl group is substituted with an aryl group, for example, a phenylmethyl group or a phenylethyl group. The carbon number of the aralkyl group is not particularly limited, but is preferably in the range of 6 or more and 40 or less.

The aryl group may be either a monocyclic ring or a fused ring, and may be, for example, a phenyl group, a naphthyl group, a fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthryl group, an anthrasenyl group, a benzophenanthryl group or a benzo. It shows an aromatic hydrocarbon group such as anthrasenyl group, chrysenyl group, pyrenyl group, fluoranthenyl group, triphenylenyl group, benzofluoranthenyl group, dibenzoanthrasenyl group, perylenel group and helisenyl group. Of these, a group selected from the group consisting of a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, an anthracenyl group, a pyrenyl group, a fluoranthenyl group and a triphenylenyl group is preferable. The aryl group may be substituted or unsubstituted. In the present invention, a group in which a plurality of phenyl groups such as a biphenyl group and a terphenyl group are bonded via a single bond is treated as a phenyl group having an aryl group as a substituent. The number of carbon atoms of the aryl group is not particularly limited, but is preferably in the range of 6 or more and 40 or less, and more preferably 6 or more and 30 or less. Further, in the case of a phenyl group, when there are substituents on two adjacent carbon atoms in the phenyl group, a ring structure may be formed between these substituents.

The heteroaryl group may be either a monocyclic group or a fused ring, and may be, for example, a pyridyl group, a furanyl group, a thiophenyl group, a quinolinyl group, an isoquinolinyl group, a pyrazinyl group, a pyrimidyl group, a pyridazinyl group, a triazinyl group, a naphthyldinyl group, a synnolinyl group. Phtalazinyl group, quinoxalinyl group, quinazolinyl group, benzofuranyl group, benzothiophenyl group, indolyl group, dibenzofuranyl group, dibenzothiophenyl group, carbazolyl group, benzocarbazolyl group, carbolinyl group, indolocarbazolyl group, benzo Flocarbazolyl group, benzothienocarbazolyl group, dihydroindenocarbazolyl group, benzoquinolinyl group, acridinyl group, dibenzoacrydinyl group, benzoimidazolyl group, imidazole pyridyl group, benzoxazolyl group, benzothiazolyl group, fe Indicates a cyclic aromatic group having an atom other than carbon and hydrogen, that is, a hetero atom in one or more rings, such as a nantrolinyl group. As the hetero atom, a nitrogen atom, an oxygen atom, or a sulfur atom is preferable. The heteroaryl group may be substituted or unsubstituted. The number of carbon atoms of the heteroaryl group is not particularly limited, but is preferably in the range of 2 or more and 40 or less, and more preferably 2 or more and 30 or less.

Halogen refers to an atom selected from fluorine, chlorine, bromine and iodine.

The cyano group is a functional group whose structure is represented by -CN. Here, it is the carbon atom that is bonded to the other group.

The formyl group is a functional group whose structure is represented by -C (= O) H. Here, it is the carbon atom that is bonded to the other group.

The acyl group refers to a functional group in which an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, etc., such as an acetyl group, a propionyl group, a benzoyl group, and an acryryl group are bonded via a carbonyl group. .. 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, and more preferably 2 or more and 30 or less.

The alkoxycarbonyl group refers to, for example, a functional group in which an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group and the like are bonded 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, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, isopropoxymethoxycarbonyl group, hexyloxycarbonyl group, phenoxycarbonyl group and the like can be mentioned.

The carbamoyl group refers to, for example, a functional group in which an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group and the like are bonded via an amide bond. These substituents may be further substituted. The number of carbon atoms of the amide group is not particularly limited, but is preferably in the range of 1 or more and 20 or less. More specifically, a methylamide group, an ethylamide group, a propylamide group, a butyramide group, an isopropylamide group, a hexylamide group, a phenylamide group and the like can be mentioned.

The alkylsulfonyl group and arylsulfonyl group indicate, for example, a functional group in which an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group and the like are _{bonded via an −S (= O) 2-bond.} These substituents may be further substituted. The number of carbon atoms of the alkylsulfonyl group and the arylsulfonyl group is not particularly limited, but is preferably in the range of 1 or more and 20 or less.

The alkoxysulfonyl group refers to, for example, a functional group in which an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group and the like are bonded via a sulfonic acid ester bond. Here, the sulfonic acid ester bond refers to a carbonyl portion of the ester bond, that is, -C (= O)-replaced with a sulfonyl moiety, that is, -S (= O) _2- . Moreover, 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.

The aminosulfonyl group refers to, for example, a functional group in which an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group and the like are bonded via a sulfonamide bond. Here, the sulfone amide bond refers to a carbonyl portion of the ester bond, that is, -C (= O)-replaced with a sulfonyl moiety, that is, -S (= O) _2- . Moreover, 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.

The amino group is a substituted or unsubstituted amino group. Examples of the substituent in the case of substitution include an aryl group, a heteroaryl group, a linear alkyl group and a branched alkyl group. As the aryl group and heteroaryl group, a phenyl group, a naphthyl group, a pyridyl group and a quinolinyl group are preferable. These substituents may be further substituted. The number of carbon atoms is not particularly limited, but is preferably 2 or more and 50 or less, more preferably 6 or more and 40 or less, and particularly preferably 6 or more and 30 or less.

The silyl group indicates a functional group to which a substituted or unsubstituted silicon atom is bonded, and is, for example, an alkylsilyl group such as a trimethylsilyl group, a triethylsilyl group, a tert-butyldimethylsilyl group, a propyldimethylsilyl group, or a vinyldimethylsilyl group. , And arylsilyl groups such as phenyldimethylsilyl group, tert-butyldiphenylsilyl group, triphenylsilyl group and trinaphthylsilyl group. Substituents on silicon may be further substituted. The number of carbon atoms of the silyl group is not particularly limited, but is preferably in the range of 1 or more and 30 or less.

The siloxanyl group refers to a silicon compound group via an ether bond such as a trimethylsiloxanyl group. Substituents on silicon may be further substituted.

The boryl group is a substituted or unsubstituted boryl group. Examples of the substituent in the case of substitution include an aryl group, a heteroaryl group, a linear alkyl group, a branched alkyl group, an aryl ether group, an alkoxy group and a hydroxyl group, and among them, an aryl group and an aryl ether group are preferable.

The phosphine oxide group is a group represented by −P (= O) R ¹⁶ R ^17. R ¹⁶ and R ¹⁷ are independently selected from the same group as ^{R 1} to R ^6.

The range of substitutable substituents in the case of substitution in the description of "may be substituted or unsubstituted" and the description of "substituents may be further substituted" in the description of each group described above is substituted. In comparison with the previous compound, it is the range of substituents that are evaluated to be chemically equivalent or have almost no effect on the performance when used in a light emitting element. From another point of view, it means that it includes a range that can be evaluated as an equal object from the viewpoint of being used for a light emitting element. Further, the above description of each group is used for the description of each group in the general formulas (3) and (4) described later, and "substitution or no substitution" in the description of ^{R 7} to R ¹⁵ and Ar ^{1 is used.} Regarding the range of substituents in the case of substitution in the description of "", the case of substitution in the above description of "substituted or unsubstituted" and "substituents may be further substituted". It has the same meaning as the range of replaceable substituents.

The pyromethene boron complex has a strong and highly planar skeleton, and therefore exhibits a high fluorescence quantum yield. Further, since the peak half width of the emission spectrum is small, efficient emission and high color purity can be achieved in the emission element. In order to further improve the luminous efficiency, it is effective to suppress the rotation / vibration of the substituent of the pyromethene boron complex, reduce the energy loss, and improve the fluorescence quantum yield. Further, in order to improve the color purity, it is effective to reduce the vibrational relaxation in the excited state of the pyrromethene boron complex and reduce the half width of the emission spectrum. From this point of view, in the structure represented by the general formula (2), ^{it is preferable to use a structure in which X 1} is a carbon atom and the above-mentioned atom or monovalent group is bonded.

By using a ^{carbon atom in which X 1} is a carbon atom and one of the above-mentioned atoms or monovalent groups is bonded to the carbon atom, a pyromethene boron complex having a high fluorescence quantum yield and a small half-value width can be provided. .. Furthermore, when the group bonded to the bridge head position suppresses intramolecular rotation with respect to the pyrromethene skeleton, it is possible to suppress energy deactivation, which is advantageous for improving luminous efficiency. In addition, the stability of the pyromethene boron complex affects the durability of the light emitting device. In order to further improve the stability, it is preferable to introduce a bulky substituent at the bridge head position. By introducing a bulky substituent, the pyrromethene skeleton can be protected from interaction with other surrounding molecules.

When X ¹ is a carbon atom, as a particularly preferable monovalent group bonded to the carbon atom, the viewpoint represented by the following general formula (3) or general formula (4) can suppress energy deactivation. Is preferable.

(Here, R ⁹ to R ¹¹ are independently hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted alkenyl. Group, substituted or unsubstituted cycloalkenyl group, substituted or unsubstituted alkynyl group, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, hydroxyl group, thiol group, substituted or unsubstituted alkoxy group, substituted Alternatively, an 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 carboxy group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or Unsubstituted carbamoyl group, substituted or unsubstituted alkylsulfonyl group, substituted or unsubstituted arylsulfonyl group, substituted or unsubstituted aminosulfonyl group, substituted or unsubstituted amino group, nitro group, substituted or unsubstituted silyl An atom or group selected from the group consisting of a ring structure formed between a group and an adjacent group.
R ⁷ and R ⁸ are groups independently selected from the group consisting of substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups, respectively. )

(Here, R ¹² to R ¹⁴ are independently hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted alkenyl. Group, substituted or unsubstituted cycloalkenyl group, substituted or unsubstituted alkynyl group, hydroxyl group, thiol group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted aryloxy group, substituted Alternatively, an unsubstituted 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, a carboxy group, a substituted or unsubstituted alkoxycarbonyl group, a 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, An atom or group selected from the group consisting of a nitro group, a substituted or unsubstituted silyl group, a substituted or unsubstituted siroxanyl group, a substituted or unsubstituted boryl group and a substituted or unsubstituted phosphine oxide group.
R ¹⁵ is 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 Substituent alkynyl group, hydroxyl group, thiol 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, carboxy group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted alkylsulfonyl group , Substituent 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 A group selected from the group consisting of a substituted siloxanyl group, a substituted or unsubstituted boryl group and a substituted or unsubstituted phosphine oxide group.
Ar ¹ is a group selected from the group consisting of substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups. )
Further, when the group represented by the general formula (3) is contained, in the pyrometheneboron compound represented by the general formula (2), Z ¹ and Z ² are independently substituted or unsubstituted alkyl groups. , substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aryl group, a halogen atom and a group selected from the group consisting of cyano ^{^{group,, R 1, R 3,}} R 4 And R ⁶ are independently substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups (where these aryl groups and heteroaryl groups may be monocyclic or fused rings, respectively. When ^{one or both of R 1} and R ⁶ are monocyclic aryl groups and heteroaryl groups, the monocyclic aryl groups and heteroaryl groups are one or more secondary alkyl groups and one or more. It has a tertiary alkyl group, one or more aryl groups or one or more heteroaryl groups as substituents, or has a total of two or more methyl groups and primary alkyl groups as substituents. ), R ² and R ⁵ are independently hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkenyl groups, substituted or unsubstituted alkenyl groups, respectively. Aryl group, substituted or unsubstituted heteroaryl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, halogen atom, cyano group. , A carboxy group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted amino group, a nitro group, and an atom or group selected from the group consisting of a substituted or unsubstituted silyl group. It is preferable to have. However, in this case, ^{one or both of R 4} and R ⁵ and ^{one or both of R 2} and R ³ have a bond between the above groups via one or two atoms. It may be formed.

The larger the number of carbon atoms in the primary alkyl group, secondary alkyl group, and tertiary alkyl group described above is, the more sterically hindered it is, which is preferable. However, from the viewpoint of ease of synthesis as a compound, it is preferable. It is preferably about 2 to 10, and more preferably 4 to 10.

Further, Z ¹ and Z ² are preferably an alkyl group, an alkoxy group, an aryl ether group, a halogen or a cyano group from the viewpoint of light emission characteristics and thermal stability. Further, from the viewpoint that the excited state is stable and a higher fluorescence quantum yield can be obtained, and the durability can be improved, Z ¹ and Z ² are more preferably electron-attracting groups, and more specifically. Is more preferably a fluorine atom, a fluorine-containing alkyl group, a fluorine-containing alkoxy group, a fluorine-containing aryl ether group or a cyano group, further preferably a fluorine atom or a cyano group, and most preferably a fluorine atom. preferable.

R ¹ and R ⁶ are groups that contribute to the stability and luminous efficiency of the pyrromethene boron complex compound. Stability refers to electrical and thermal stability. Electrical stability means that deterioration of the compound such as decomposition is unlikely to occur when the light emitting element is continuously energized. Thermal stability means that the deterioration of the compound is unlikely to occur due to heating processes such as sublimation purification and vapor deposition during manufacturing and the environmental temperature around the light emitting element. Since the luminous efficiency decreases when the compound is altered, the stability of the compound is important for improving the durability of the light emitting device. R ¹ and R ⁶ are preferably substituted or unsubstituted aryl groups from the viewpoint of compound stability and luminous efficiency. R ¹ and R ⁶ are preferably groups having a large steric hindrance in the above group in order to prevent aggregation of pyrromethene boron complexes and avoid concentration quenching. From this point of view, R ¹ and R ⁶ are phenyl groups having one or more tertiary alkyl groups as substituents, phenyl groups having one or more aryl groups as substituents, and one or more heteroaryl groups. It has a total of two or more substituents, a phenyl group, a methyl group and a primary alkyl group, and at least one of them is substituted at the 2-position with respect to the bond site with the pyrrole ring. It is preferably selected from the group consisting of a phenyl group and a fused ring-type aromatic hydrocarbon group. Further, since the smaller the degree of freedom of rotation or vibration is, the lower the efficiency due to heat deactivation can be suppressed ^{, it is preferable that R 1} and R ⁶ are functional groups having a rigid structure or a highly symmetric structure. From this point of view, R ¹ and R ⁶ are for a phenyl group having one or more tert-butyl groups as a substituent, a phenyl group having one or more phenyl groups as a substituent, or at least a bond site with a pyrrole ring. A phenyl group that is either a phenyl group in which a methyl group is substituted at the 2- or 6-position and has a substituent that is linearly symmetric with the bond with pyrrole as the axis of symmetry, or an unsubstituted fused ring-type aromatic. It is more preferably a hydrocarbon group. Further, from the viewpoint of ease of production, it may be a 2,6-dimethylphenyl group, a mesityl group, a 4-tert-butylphenyl group, a 3,5-ditert-butylphenyl group, a 4-biphenyl group or a 1-naphthyl group. More preferred.

R ³ and R ⁴ are groups that contribute to the control of the emission wavelength. In order to make the pyrromethene boron complex emit red light, a method of extending the conjugation and lengthening the emission wavelength by directly bonding an aryl group or a heteroaryl group to the pyrromethene metal complex skeleton can be mentioned. For this reason, R ³ and R ⁴ are substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups, but from the viewpoint of compound stability, they are substituted or unsubstituted. Aryl groups are more preferred.

R ² and R ⁵ mainly affect the peak wavelength, half width of emission spectrum, stability, or crystallinity. From the viewpoint of narrowing the half width of the emission spectrum, stability affecting device durability, and ease of manufacture including recrystallization purification, at least one or more preferably both of ^{R 2} and R ^{5 are hydrogen atoms.} Alternatively, it is preferably a substituted or unsubstituted alkyl group.

Further, in the compound represented by the general formula (2), any ^{of the set of R 1} and R ² , the set of R ² and R ³ , the set of R ⁴ and R ⁵ , and the set of R ⁵ and R ^6. In one or more pairs, a bond may be formed between the groups constituting the pair to form a ring, or a bond may be formed between ^{Z 1} and Z ^{2 to form a ring.} it may be one that is formed, but in place of this sense, in the R ¹ to the R ^6, condensed and pyrromethene ring, preferably as a fused ring, i.e. contain two carbons pyrromethene ring It means that a ring of five-membered ring to seven-membered ring can be formed, and Z ¹ and Z ² include that a heterocycle containing boron can be provided as a partial structure.

Further, in order to improve the luminous efficiency, it is effective to suppress the rotation / vibration of the group represented by the general formula (3), reduce the energy loss, and improve the fluorescence quantum yield. In order to suppress the rotation and vibration of the group represented by the general formula (3), R ⁷ and R ⁸ are substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups. Is selected from. Of these, at least one is preferably a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group. On the other hand, from the viewpoint of ease of production, one of R ⁷ and R ⁸ is preferably a substituted or unsubstituted alkyl group, and more preferably a methyl group. Further, R ⁹ to R ¹¹ are used for adjusting the peak wavelength, crystallinity, sublimation temperature and the like. Particularly affecting peak wavelength substituents attached to the 4-position of the pyrromethene skeleton, that is, R ^10. If R ¹⁰ is an electron donating group, the emission peak wavelength shifts to the short wavelength side. Specific examples of the electron donating group include a methyl group, an ethyl group, a tert-butyl group, a cyclohexyl group, a methoxy group, an ethoxy group, a phenyl group, a tolyl group, a naphthyl group, a furanyl group and a dibenzofuranyl group. NS. In particular, when R ¹⁰ is an alkoxy group such as a methoxy group or an ethoxy group having a strong electron donating property, the short wavelength shift is large, which is useful for wavelength adjustment. On the other hand, if R ¹⁰ is an electron-attracting group, the emission peak shifts to the long wavelength side. Specific examples of the electron-attracting group include a fluorine atom, a trifluoromethyl group, a cyano group, a pyridyl group, and a pyrimidyl group. In particular, when R ¹⁰ is a group selected from a fluorine atom, a trifluoromethyl group and a cyano group having strong electron attraction, the long wavelength shift is large, which is useful for wavelength adjustment. However, the electron donating group and the electron attracting group are not limited to these.

Further, when the group represented by the general formula (4) is contained, in the pyrometheneboron compound represented by the general formula (2), Z ¹ and Z ² are independently substituted or unsubstituted alkyl groups, respectively. , substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aryl group, a halogen atom and atom or group selected from the group consisting of cyano group,, R 1 ^~ R ⁶ is , Independently, hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylthio group, substituted or Consists of an 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 siroxanyl group. It is a group selected from the group, but ^{it is desirable that at least one of R 1} , R ³ , R ⁴ , and R ⁶ is a hydrogen atom or a substituted or unsubstituted alkyl group.

R ¹ and R ⁶ affect the emission peak wavelength, crystallinity, sublimation temperature, etc. of the pyrromethene boron complex. From the viewpoint of reducing the half width of the emission spectrum, R ¹ and R ⁶ are preferably hydrogen atoms or alkyl groups. Further, from the viewpoint of further improving the fluorescence quantum yield, R ¹ and R ⁶ are more preferably alkyl groups, and further preferably methyl groups from the viewpoint of ease of production.

R ³ and R ⁴ mainly affect the emission peak wavelength, the half width of the emission spectrum, the stability, or the crystallinity of the pyrromethene boron complex. From the viewpoint of making the half-value width of the emission spectrum smaller, improving the stability, and easiness of synthesis including recrystallization, at least one or preferably both of ^{R 3} and R ^{4 are hydrogen atoms.} It is preferably a group selected from the group consisting of substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups and substituted or unsubstituted heteroaryl groups. Further, from the viewpoint of further reducing the half width, R ³ and R ⁴ are more preferably alkyl groups, and further preferably methyl groups from the viewpoint of ease of production.

R ² and R ⁵ mainly affect the emission peak wavelength, the half width of the emission spectrum, the stability, or the crystallinity of the pyrromethene boron complex. From the viewpoint of reducing the half width of the emission spectrum, improving the stability, and easiness of synthesis including recrystallization purification, at least one or preferably both of ^{R 2} and R ^{5 are hydrogen atoms.} It is preferably a substituted or unsubstituted alkyl group, and it is more preferable that both are hydrogen atoms from the viewpoint of ease of production.

Further, in order to improve the luminous efficiency, it is effective to suppress the rotation / vibration of the group represented by the general formula (4), reduce the energy loss, and improve the fluorescence quantum yield. In order to suppress the rotation / vibration of the group represented by the general formula (4), ^{it is more preferable that R 11} and Ar ¹ are a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group. , Phenyl group, 2,6-dimethylphenyl group, mesityl group, 4-tert-butylphenyl group, 3,5-ditert-butylphenyl group, 4-methoxyphenyl group, 4-biphenyl group from the viewpoint of ease of production. Alternatively, it is more preferably a 1-naphthyl group.

To introduce an aryl group or a heteroaryl group into the pyrromethene skeleton, for example, under a metal catalyst such as palladium, carbon-is used by a coupling reaction between a halogenated derivative of the pyrromethene boron complex and a boronic acid or boronic acid ester derivative. Examples include, but are not limited to, methods of forming carbon bonds. Similarly, to introduce an amino or carbazolyl group into the pyrromethene skeleton, for example, under a metal catalyst such as palladium, carbon-nitrogen using a coupling reaction of a halogenated derivative of the pyrromethene boron complex with an amine or carbazole derivative. Examples include, but are not limited to, methods of generating bonds.

The obtained pyromethene boron complex is subjected to organic synthetic purification such as recrystallization and column chromatography, and then the low boiling point component is removed by purification by heating under reduced pressure, which is generally called sublimation purification, to improve the purity. Is preferable. The heating temperature in the sublimation purification is not particularly limited, but is preferably 330 ° C. or lower, more preferably 300 ° C. or lower, from the viewpoint of preventing thermal decomposition of the pyromethene boron complex. The purity of the pyrromethene boron complex produced in this manner is preferably 99% by weight or more from the viewpoint of enabling the light emitting device to exhibit stable characteristics.

The optical properties of the pyrromethene boron complex can be obtained by measuring the absorption spectrum and emission spectrum of the diluted solution. The solvent is not particularly limited as long as it dissolves the pyrromethene boron complex and the absorption spectrum of the solvent is transparent so as not to overlap with the absorption spectrum of the pyromethene boron complex. Specifically, toluene and the like are exemplified. The concentration of the solution is not particularly limited as long as it has sufficient absorbance and does not cause concentration dimming, but it is preferably in the range of ^{1 × 10 -4} mol / L to 1 × 10 ^{-7 mol / L.} More preferably, it is in the range of 1 × 10 ^-5 mol / L to 1 × 10 ^{-6 mol / L.}

The absorption spectrum can be measured with a general ultraviolet-visible spectrophotometer. The emission spectrum can be measured by a general fluorescence spectrophotometer. Further, it is preferable to use an absolute quantum yield measuring device using an integrating sphere for measuring the fluorescence quantum yield. In order to achieve high color purity, it is preferable that the emission spectrum of the light emitted by the pyromethene boron complex by irradiation with excitation light is sharp.

In addition, high brightness and high color purity can be achieved by the resonance effect of the microcavity structure in the top emission element, which is the mainstream in display devices and lighting devices, but when the emission spectrum is sharp, this resonance effect appears more strongly and is high. It is advantageous for efficiency. From this viewpoint, 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.

The luminous efficiency of the light emitting element depends on the fluorescence quantum yield of the light emitting material itself. Therefore, it is desired that the fluorescence quantum yield of the light emitting material is as close to 100% as possible. The pyromethene boron complex represented by the general formula (2) can obtain a high fluorescence quantum yield by suppressing rotation and vibration at the bridge head position and reducing heat deactivation. From the above viewpoint, the fluorescence quantum yield of the pyrromethene boron complex is preferably 90% or more, more preferably 95% or more. However, the fluorescence quantum yield shown here is obtained by measuring a diluted solution using toluene as a solvent with an absolute quantum yield measuring device.

When the first compound is a thermally activated delayed fluorescent compound, the light emitting layer further has a singlet energy (meaning the energy difference between the lowest excited singlet state and the ground state; the same applies hereinafter) of the first compound. Compounds larger than the singlet energy (hereinafter, such compounds may be referred to as "third compounds") may be included. As a result, the third compound can have a function of confining the energy of the light emitting material in the light emitting layer, and can efficiently emit light. Further, it is preferable that the lowest excited triplet energy of the third compound (referred to as the energy difference between the lowest excited triplet state and the ground state; the same applies hereinafter) is larger than the lowest excited triplet energy of the first compound. As such a third compound, an organic compound having a high charge transporting ability and a high glass transition temperature is preferable.

The third compound may be composed of a single compound or two or more kinds of materials. When two or more kinds of materials are used as the third compound, it is preferable that the third compound has an electron transporting property and the third compound has a hole transporting property. By combining the third compound with electron transporting property and the third compound with hole transporting property at an appropriate mixing ratio, the charge balance in the light emitting layer is adjusted and the bias of the light emitting region is suppressed to suppress the bias of the light emitting device. It can improve reliability and durability. Further, an excited complex may be formed between the electron-transporting third compound and the hole-transporting third compound.

From the above viewpoint, it is preferable that the first compound and the third compound satisfy the relational expressions of the following formulas 1 to 4, respectively. Further, it is more preferable to satisfy the formulas 1 and 2, and it is further preferable to satisfy the formulas 3 and 4. Further, it is more preferable to satisfy all of the formulas 1 to 4.
S1 (electron-transporting third compound)> S1 (first compound) (formula 1)
S1 (hole transporting third compound)> S1 (first compound) (formula 2)
T1 (electron-transporting third compound)> T1 (first compound) (formula 3)
T1 (hole-transporting third compound)> T1 (first compound) (formula 4)
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.

Examples of the third electron-transporting compound include compounds containing a π-electron-deficient heteroaromatic ring. Specific examples thereof include a heterocyclic compound having a polyazole skeleton, a heterocyclic compound having a quinoxaline skeleton or a dibenzoquinoxaline skeleton, a heterocyclic compound having a diazine skeleton (pyrimidine skeleton or pyrazine skeleton), and a heterocyclic compound having a pyridine skeleton. .. Moreover, as the above-mentioned third hole transporting compound, a compound containing a π-electron excess type heteroaromatic ring and the like can be mentioned. Specifically, a compound having a carbazole skeleton is exemplified.

As described above, the method for forming each of the above-mentioned layers constituting the light emitting device of the present invention may be either a dry process or a wet process, and resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination method, coating method, inkjet method, printing may be used. Although the method is not particularly limited, resistance heating vapor deposition is usually preferable from the viewpoint of device characteristics. The thickness of the organic layer is not particularly limited because it depends on the resistance value of the luminescent substance, but it is preferably 1 to 1000 nm. The film thicknesses of the light emitting layer, the electron transport layer, and the hole transport layer are preferably 1 nm or more and 200 nm or less, and more preferably 5 nm or more and 100 nm or less, respectively.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not construed as being limited to these. First, the evaluation method will be described.

(1) Nuclear Magnetic Resonance Analysis (NMR)
The 400 MHz NMR spectrum of the white solid obtained in Synthesis Example 2 was measured using a JNM-AL400 type nuclear magnetic resonance apparatus (manufactured by JEOL Ltd.). The chemical shift is expressed in δ (unit: ppm) with reference to tetramethylsilane, and the signals are s (single line), d (double line), t (triple line), q (quadruple line), and m, respectively. It was represented by (multiple lines), br (wide), dd (double double lines), and dt (double triple lines). The solvent name shown in the NMR data indicates the solvent used for the measurement.

(2) Powder X-ray Diffraction The white solid obtained in each Example and Comparative Example was used as a sample plate (material: silicon; depth: 0. 2 mm) was filled, the surface was flattened to prepare a measurement sample, and powder X-ray diffraction was measured under the following conditions.
X-ray source: CuKα ray * Curved crystal monochromator (graphite) is used Output: 40kV / 50mA
Divergence slit: 1/2 °
Divergence vertical restriction slit: 5 mm
Scattering slit: 1/2 °
Light receiving slit: 0.15 mm
Detector: Scintillation counter Scan method: 2θ / θ scan, continuous scan Measurement range (2θ): 2 to 30 °
Scan speed (2θ): 20 ° / min
Counting step (2θ): 0.04 °.

(3) Endothermic peak For the white solids obtained in each Example and Comparative Example, a differential thermal thermal weight simultaneous measurement device (TG-DTA device; Rigaku Co., Ltd .; TG8120 Smart Roader) was used to simultaneously display the differential thermal weight. The measurement was performed, and the temperature of the peak top indicated by the DTA curve was defined as the endothermic peak.
Temperature rise rate: 5 ° C / min Atmosphere: Dry nitrogen (flow rate: 100 mL / min)
Sample cell: Aluminum open cell Sample amount: 5 to 15 mg.

(4) Chemical Purity For the white solids obtained in each Example and Comparative Example, the chemical purity was measured using high performance liquid chromatography (hereinafter referred to as HPLC), and for all peaks except blank peaks and residual solvent peaks. The area percentage of the peak to be measured was taken as the chemical purity. The sample for HPLC analysis was prepared by dissolving 4 mg of the white solid obtained in each Example and Comparative Example in 40 mL of tetrahydrofuran.
HPLC: LC-2010CHT (Shimadzu Corporation)
Detection: UV (254 nm)
Column: Mightysil RP-8GP (Kanto Chemical Co., Inc.)
Column size: 250 x 4.6 mm (5 μm)
Column temperature: 45 ° C
Mobile phase: Liquid A 0.1% aqueous phosphoric acid solution (weight ratio)
Liquid B Acetonitrile / tetrahydrofuran = 80/20 (volume ratio)
Deployment conditions: A / B = 55/45 → 0/100 (volume ratio); 0 → 25 minutes, linear gradient A / B = 0/100 (volume ratio); 25 → 30 minutes, constant A / B = 0 / 100 → 55/45 (volume ratio); 30 → 31 minutes, linear gradient A / B = 55/45 (volume ratio), 31 → 35 minutes, constant flow rate: 1.0 mL / min Injection volume: 10 μL.

(5) Residual solvent amount The white solid obtained in each Example and Comparative Example was subjected to NMR measurement, and the molar ratio was calculated from the respective peak integrated values of the compound to be measured and the residual solvent, and compared with each Example. The amount of residual solvent was calculated from the weight and molar ratio of the white solid obtained by the example. When a plurality of residual solvents were confirmed, they were calculated as the total value.

Next, an example of synthesizing the precursor of the crystal of the present invention, an example of producing the crystal of the present invention and a comparative example, and their evaluation results will be described.

(Synthesis Example 1) Synthesis of 2-Phenyl-1,10-phenanthroline:
A phenyllithium solution (1.07 M, 100 mL) was added to a toluene (250 mL) solution of 1,10-phenanthroline (9.64 g) under an argon atmosphere, and the mixture was stirred at 0 ° C. for 1.5 hours. Subsequently, water (150 mL) was added to the reaction mixture, the mixture was extracted three 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 solution of the obtained concentrate in dichloromethane (300 mL), and the mixture was stirred at room temperature for 56 hours. Subsequently, the reaction mixture was filtered, and the residue was washed with dichloromethane (500 mL), and then the filtrate and the washing liquid were combined and concentrated. The resulting concentrate was suspended in ethyl acetate (30 mL) and stirred at 0 ° C. The precipitate was filtered and dried under reduced pressure at 80 ° C. to obtain 9.44 g of 2-phenyl-1,10-phenanthroline as a white solid.

(Synthesis Example 2) Synthesis of 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene:
Under an argon atmosphere, n-butyllithium (1.52M, 17 mL) was added to a solution of 1,3-dibromobenzene (1.2 mL) in n-hexane (35 mL), and the mixture was stirred under reflux for 1 hour. Subsequently, the reaction mixture was cooled to 0 ° C., a solution of 2-phenyl-1,10-phenanthroline (5.10 g) in tetrahydrofuran (100 mL) was added, and the mixture was stirred at 0 ° C. for 2 hours. Subsequently, water (100 mL) was added to the reaction mixture, the mixture was extracted three 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 solution of the obtained concentrate in dichloromethane (180 mL), and the mixture was stirred at room temperature for 12 hours. Subsequently, the reaction mixture was filtered, and the residue was washed with dichloromethane (750 mL), and then the filtrate and the washing liquid were combined and concentrated.

The obtained concentrate was suspended in a mixed solution of dichloromethane / chloroform (volume ratio 1/10, 85 mL) and stirred at 0 ° C. The precipitate was filtered and dried under reduced pressure at 100 ° C. to obtain 3.25 g of 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene as a white solid. The NMR chemical shift of the obtained compound is shown below.
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).

(Example 1)
Under an argon atmosphere, 1,3-dimethyl-2-imidazolidinone was added to 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene (1.28 g) obtained in Synthesis Example 2. (4.9 mL, specific density 1.05) and toluene (8.7 mL, specific density 0.86) were added, and the mixture was stirred at 110 ° C. for 0.5 hours. Subsequently, the mixture was cooled to 0 ° C. over 1 hour and then stirred at 0 ° C. for 1 hour. The precipitate was filtered and dried under reduced pressure at 20 ° C., tetrahydrofuran (16.7 mL, specific density 0.89) was added to the obtained precipitate, and the mixture was heated under reflux and stirred for 2 hours. Subsequently, the mixture was cooled to 0 ° C. over 1 hour and then stirred at 0 ° C. for 1 hour. The precipitate was filtered and dried under reduced pressure at 100 ° C. to obtain a white solid (yield 0.71 g, recovery rate 55%).

When the powder X-ray diffraction and the endothermic peak were measured for the obtained white solid by the above-mentioned method, the measurement results were as follows, and it was confirmed that the white solid was a B-type crystal. The powder X-ray diffraction pattern is shown in FIG. 1, and the differential thermal analysis curve is shown in FIG. 2, respectively.
Diffraction angle 2θ (°): 6.7, 8.2, 13.7, 17.7, 22.2
Endothermic peak: 182 ° C
Table 1 shows the results of evaluating the chemical purity and the amount of residual solvent by the above-mentioned method.

(Example 2)
Under an argon atmosphere, 1,3-dimethyl-2-imidazolidinone was added to 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene (0.97 g) obtained in Synthesis Example 2. (2.2 mL, specific gravity 1.05) and toluene (6.6 mL, specific density 0.86) were added, and the mixture was stirred at 120 ° C. for 0.5 hours. Subsequently, the mixture was cooled to 0 ° C. over 3 hours and then stirred at 0 ° C. for 2 hours. The precipitate was filtered and 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 under reflux and stirred for 2 hours. Subsequently, the mixture was cooled to 0 ° C. over 3 hours and then stirred at 0 ° C. for 2 hours. The precipitate was filtered and dried under reduced pressure at 100 ° C. to obtain a white solid (yield 0.70 g, recovery rate 72%).

When the powder X-ray diffraction and the endothermic peak were measured for the obtained white solid by the above-mentioned method, the measurement results were as follows, and it was confirmed that the white solid was a B-type crystal.
Diffraction angle 2θ (°): 6.7, 8.2, 13.7, 17.7, 22.2
Endothermic peak: 182 ° C
Table 1 shows the results of evaluating the chemical purity and the amount of residual solvent by the above-mentioned method.

(Example 3)
Under an argon atmosphere, 1,3-dimethyl-2-imidazolidinone was added to 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene (0.30 g) obtained in Synthesis Example 2. (1.1 mL, specific gravity 1.05) and anisole (2.1 mL, specific gravity 0.99) were added, and the mixture was stirred at 100 ° C. for 0.5 hours. Subsequently, the mixture was cooled to 0 ° C. over 1 hour and then stirred at 0 ° C. for 2 hours. The precipitate was filtered and dried under reduced pressure at 100 ° C. to obtain a white solid (yield 0.24 g, recovery rate 80%).

When the powder X-ray diffraction and the endothermic peak were measured for the obtained white solid by the above-mentioned method, the measurement results were as follows, and it was confirmed that the white solid was a C-shaped crystal. The powder X-ray diffraction pattern is shown in FIG. 3, and the differential thermal analysis curve is shown in FIG. 4, respectively.
Diffraction angle 2θ (°): 5.0, 7.5, 8.7, 12.5, 17.3
Endothermic peak: 245 ° C
Table 1 shows the results of evaluating the chemical purity and the amount of residual solvent by the above-mentioned method.

(Example 4)
N-methylpyrrolidone (1.1 mL, specific density 1) was added to 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene (0.30 g) obtained in Synthesis Example 2 under an argon atmosphere. .03) and anisole (2.1 mL, specific density 0.99) were added, and the mixture was stirred at 100 ° C. for 0.5 hours. Subsequently, the mixture was cooled to 0 ° C. over 1 hour and then stirred at 0 ° C. for 2 hours. The precipitate was filtered and dried under reduced pressure at 100 ° C. to obtain a white solid (yield 0.23 g, recovery rate 77%).

When the powder X-ray diffraction and the endothermic peak were measured for the obtained white solid by the above-mentioned method, the measurement results were as follows, and it was confirmed that the white solid was a C-shaped crystal.
Diffraction angle 2θ (°): 5.0, 7.5, 8.7, 12.5, 17.3
Endothermic peak: 245 ° C
Table 1 shows the results of evaluating the chemical purity and the amount of residual solvent by the above-mentioned method.

(Example 5)
Under an argon atmosphere, N, N-dimethylacetamide (1.1 mL,) was added to 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene (0.30 g) obtained in Synthesis Example 2. Anisole (2.1 mL, specific gravity 0.99) was added, and the mixture was stirred at 100 ° C. for 0.5 hours. Subsequently, the mixture was cooled to 0 ° C. over 1 hour and then stirred at 0 ° C. for 2 hours. The precipitate was filtered and dried under reduced pressure at 100 ° C. to obtain a white solid (yield 0.25 g, recovery rate 83%).

(Example 6)
Under an argon atmosphere, 1,3-dimethyl-2-imidazolidinone was added to 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene (0.30 g) obtained in Synthesis Example 2. (1.1 mL, specific gravity 1.05) and anisole (2.1 mL, specific gravity 0.99) were added, and the mixture was stirred at 100 ° C. for 0.5 hours. Subsequently, the mixture was cooled to 0 ° C. over 4 hours and then stirred at 0 ° C. for 2 hours. The precipitate was filtered and dried under reduced pressure at 25 ° C. to obtain a white solid (yield 0.30 g, recovery rate 100%).

When the powder X-ray diffraction and the endothermic peak were measured for the obtained white solid by the above-mentioned method, the measurement results were as follows, and it was confirmed that the white solid was an E-type crystal. The powder X-ray diffraction pattern is shown in FIG. 5, and the differential thermal analysis curve is shown in FIG. 6, respectively.
Diffraction angle 2θ (°): 5.2, 7.0, 16.4, 20.0, 23.6
Endothermic peak: 96 ° C
Under an argon atmosphere, 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene (0.15 g) obtained from the above information was dried under reduced pressure at 100 ° C. to obtain a white solid. (Yield 0.12 g, recovery rate 80%).

When the powder X-ray diffraction and the endothermic peak were measured for the obtained white solid by the above-mentioned method, the measurement results were as follows, and it was confirmed that the white solid was a C-shaped crystal.
Diffraction angle 2θ (°): 5.0, 7.5, 8.7, 12.5, 17.3
Endothermic peak: 245 ° C
Table 2 shows the results of evaluating the chemical purity and the amount of residual solvent by the above-mentioned method.

(Comparative Example 1)
Under an argon atmosphere, 1,3-dimethyl-2-imidazolidinone was added to 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene (0.30 g) obtained in Synthesis Example 2. (0.9 mL, specific gravity 1.05) and anisole (2.1 mL, specific density 0.99) were added, and the mixture was stirred at 100 ° C. for 0.5 hours. Subsequently, the mixture was cooled to 0 ° C. over 1 hour and then stirred at 0 ° C. for 2 hours. The precipitate was filtered and dried under reduced pressure at 100 ° C. to obtain a white solid (yield 0.27 g, recovery rate 90%).

When the powder X-ray diffraction and the endothermic peak were measured for the obtained white solid by the above-mentioned method, the measurement results are as follows, and the crystal form different from the B-type crystal and the C-type crystal (“D-type”). It was confirmed that it was called "crystal"). The powder X-ray diffraction pattern is shown in FIG. 7, and the differential thermal analysis curve is shown in FIG. 8, respectively.
Diffraction angle 2θ (°): 4.8, 7.2, 9.5, 22.9, 27.6
Endothermic peak: 173 ° C
Table 2 shows the results of evaluating the chemical purity and the amount of residual solvent by the above-mentioned method.

(Comparative Example 2)
Under an argon atmosphere, methanol (18 mL, specific density 0.79) was added to 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene (0.70 g) obtained in Synthesis Example 2. , Stirred at 20 ° C. for 2 hours. The precipitate was filtered and dried under reduced pressure at 100 ° C. to obtain a white solid (yield 0.67 g, recovery rate 96%). The powder X-ray diffraction of the obtained white solid was measured by the above-mentioned method. The measurement results are shown in FIG. As shown in FIG. 9, no characteristic diffraction peak was observed, and it was amorphous. Table 2 shows the results of evaluating the chemical purity and the amount of residual solvent by the above-mentioned method.

(Comparative Example 3)
When the powder X-ray diffraction of 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene obtained in Synthesis Example 2 was measured by the above-mentioned method, it was the same as in Comparative Example 2. No characteristic diffraction peak was observed, and it was amorphous. Table 2 shows the results of evaluating the chemical purity and the amount of residual solvent by the above-mentioned method. Tables 1 and 2 show the main production methods and evaluation results of Examples 1 to 7 and Comparative Examples 1 to 3.

As shown in Tables 1 and 2, it was found that the phenanthroline derivative synthesized by the conventional method and the phenanthroline derivative washed with a methanol solvent are amorphous and have a small amount of residual solvent, but have low chemical purity. On the other hand, the D-type crystal of Comparative Example 1 has a high chemical purity but a large amount of residual solvent. Therefore, in order to obtain a phenanthroline derivative having a high chemical purity and a small amount of residual solvent, only the amorphous crystal is crystallized. Was insufficient, and it was found that it was necessary to select B-type crystals or C-type crystals with a small amount of residual solvent. Further, in Example 6, since the crystal polymorphic transition easily proceeds in the E-type crystal under the conditions of drying under reduced pressure at 100 ° C., the E-type crystal is useful as a precursor for obtaining the C-type crystal by low-temperature drying. I understood.

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

The pyrromethene boron complex compound used in the following Examples and Comparative Examples is the compound shown below. The characteristics are shown in Table 3.

(Example 7)
A glass substrate (manufactured by Geomatec Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited at 165 nm was cut into a size of 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with "Semicoclean 56" (trade name, manufactured by Furuuchi 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 the device was manufactured, placed in a vacuum vapor deposition apparatus, and evacuated ^{until the degree of vacuum in the apparatus became 5 × 10 -4} Pa or less. By the resistance heating method, HAT-CN6 was first deposited at 10 nm as a hole injection layer, and HT-1 was deposited at 180 nm as a hole transport layer. Next, as the light emitting layer, H-1 which is a host material, compound D-1 which is a dopant compound, and compound H-2 which is a TADF material are arranged in a weight ratio of 80: 1: 19. , 40 nm thick. Further, as an electron transport layer, a crystal (C-type crystal) of compound ET-1, which is a phenanthroline derivative, was used to deposit and laminate a thickness of 35 nm. Next, after depositing 2E-1 at 0.5 nm as an electron injection layer, magnesium and silver were co-deposited at 1000 nm to form a cathode, and a 5 × 5 mm square element was manufactured.

The external quantum efficiency was 11.4% when this light emitting device was ^{made to emit light at 1000 cd / m 2.} The structures of HAT-CN6, HT-1, H-1, H-2, ET-1, and 2E-1 are shown below.

(Examples 8 to 10)
A light emitting device was used in the same manner as in Example 7 except that the crystals in the crystal form shown in Table 1 were used as the crystal form of the phenanthroline derivative ET-1 and the compounds shown in Table 3 were used as the dopant material for the light emitting layer. Made and evaluated. The results are shown in Table 4.

(Example 11)
A glass substrate (manufactured by Geomatec Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited at 165 nm was cut into a size of 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with "Semicoclean 56" (trade name, manufactured by Furuuchi 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 the device was manufactured, placed in a vacuum vapor deposition apparatus, and evacuated ^{until the degree of vacuum in the apparatus became 5 × 10 -4} Pa or less. By the resistance heating method, HAT-CN6 was first deposited at 10 nm as a hole injection layer, and HT-1 was deposited at 40 nm as a hole transport layer. Next, as the light emitting layer, H-1 which is a host material, compound D-6 which is a dopant compound, and compound H-3 which is a TADF material are arranged in a weight ratio of 80: 1: 19. , 30 nm thick vapor deposition. Further, as an electron transport layer, a crystal (C-type crystal) of the compound ET-1 which is a phenanthroline derivative was used, and thin-film deposition was laminated to a thickness of 50 nm. Next, after depositing 2E-1 at 0.5 nm as an electron injection layer, magnesium and silver were co-deposited at 1000 nm to form a cathode, and a 5 × 5 mm square element was manufactured.

The external quantum efficiency was 9.2% when this light emitting device was ^{made to emit light at 1000 cd / m 2.} The structure of H-3 is shown below.

(Examples 12 to 14)
A light emitting device in the same manner as in Example 11 except that the crystals in the crystal form shown in Table 1 were used as the crystal form of the phenanthroline derivative ET-1 and the compounds shown in Table 3 were used as the dopant material for the light emitting layer. Was prepared and evaluated. The results are shown in Table 4.

(Comparative Examples 4 and 5)
The light emitting device was used in the same manner as in Example 7 except that the crystalline form of ET-1 which is a phenanthroline derivative was used as the crystal form shown in Table 2 and the compound shown in Table 3 was used as the dopant material of the light emitting layer. Was prepared and evaluated. The results are shown in Table 4.

(Comparative Examples 6 and 7)
The light emitting device was used in the same manner as in Example 11 except that the crystalline form of ET-1 which is a phenanthroline derivative was used as the crystal form shown in Table 2 and the compound shown in Table 3 was used as the dopant material of the light emitting layer. Was prepared and evaluated. The results are shown in Table 4.

From Table 4, it can be seen that Examples 7-14 have higher external quantum efficiencies than Comparative Examples 4 to 7 using the same light emitting layer. That is, as can be seen with reference to Table 4, in Examples 7 to 14 in which the B-type crystal or C-type crystal of the compound ET-1 is used as the electron transport material, the D form of the compound ET-1 is used as the electron transport material. Compared with Comparative Examples 4 to 7 in which crystalline or amorphous materials are used, it is possible to obtain a light emitting element in which the external quantum efficiency is significantly improved regardless of which thermally activated delayed fluorescent material is used for the light emitting layer. all right.

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

(Example 15)
A glass substrate (manufactured by Geomatec Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited at 165 nm was cut into a size of 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with "Semicoclean 56" (trade name, manufactured by Furuuchi 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 the device was manufactured, placed in a vacuum vapor deposition apparatus, and evacuated ^{until the degree of vacuum in the apparatus became 5 × 10 -4} Pa or less. By the resistance heating method, HAT-CN6 was first deposited at 10 nm as a hole injection layer, and HT-1 was deposited at 180 nm as a hole transport layer. Next, as the light emitting layer, H-1 which is a host material, compound D-1 which is a dopant compound, and compound H-2 which is a TADF material are arranged in a weight ratio of 80: 1: 19. , 40 nm thick. Further, as the electron transport layer, compound ET-2 is used as the electron transport material and 2E-1 is used as the donor material, and the vapor deposition rate ratio of the compounds ET-2 and 2E-1 is 1: 1 so that the thickness is 35 nm. It was laminated on the surface. Next, a crystal (C-type crystal) of the compound ET-1 which is a phenanthroline derivative is used as the electron injection layer, metallic lithium is used as the donor material, and the vapor deposition rate ratio of the compound ET-1 and the metallic lithium is 99: 1. After vapor deposition at 5 nm so as to be, magnesium and silver were co-deposited at 1000 nm to form a cathode, and a 5 × 5 mm square element was manufactured.

The external quantum efficiency was 14.4% when this light emitting device was ^{made to emit light at 1000 cd / m 2.} The structure of ET-2 is shown below.

(Examples 16 to 18)
The light emitting device was prepared in the same manner as in Example 15 except that the crystals in the crystal form shown in Table 1 were used as the crystal form of the phenanthroline derivative ET-1 and the compounds shown in Table 3 were used as the dopant material for the light emitting layer. Made and evaluated. The results are shown in Table 5.

(Example 19)
A glass substrate (manufactured by Geomatec Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited at 165 nm was cut into a size of 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with "Semicoclean 56" (trade name, manufactured by Furuuchi 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 the device was manufactured, placed in a vacuum vapor deposition apparatus, and evacuated ^{until the degree of vacuum in the apparatus became 5 × 10 -4} Pa or less. By the resistance heating method, HAT-CN6 was first deposited at 10 nm as a hole injection layer, and HT-1 was deposited at 40 nm as a hole transport layer. Next, as the light emitting layer, H-1 which is a host material, compound D-6 which is a dopant compound, and compound H-3 which is a TADF material are arranged in a weight ratio of 80: 1: 19. , 30 nm thick vapor deposition. Further, as the electron transport layer, compound ET-2 is used as the electron transport material and 2E-1 is used as the donor material, and the vapor deposition rate ratio of the compounds ET-2 and 2E-1 is 1: 1 so that the thickness is 50 nm. It was laminated on the surface. Next, a crystal (C-type crystal) of ET-1 which is a phenanthroline derivative is used as an electron injection layer, and metallic lithium is used as a donor material, and the vapor deposition rate ratio of compound ET-1 and metallic lithium becomes 99: 1. After the 5 nm vapor deposition in this manner, magnesium and silver were co-deposited with 1000 nm to form a cathode, and a 5 × 5 mm square element was produced.

The external quantum efficiency was 12.2% when this light emitting device was ^{made to emit light at 1000 cd / m 2.}

(Examples 20 to 22)
A light emitting device in the same manner as in Example 19 except that the crystals in the crystal form shown in Table 1 were used as the crystal form of the phenanthroline derivative ET-1 and the compounds shown in Table 3 were used as the dopant material for the light emitting layer. Was prepared and evaluated. The results are shown in Table 5.

(Comparative Examples 8 and 9)
A light emitting device was produced in the same manner as in Example 15 except that the crystal form shown in Table 2 was used as the crystal form of ET-1 and the compounds shown in Table 3 were used as the dopant material of the light emitting layer. evaluated. The results are shown in Table 5.

(Comparative Examples 10 and 11)
A light emitting device was produced in the same manner as in Example 19 except that the crystal form shown in Table 2 was used as the crystal form of ET-1 and the compounds shown in Table 3 were used as the dopant material of the light emitting layer. evaluated. The results are shown in Table 5.

From Table 5, it can be seen that Examples 15 to 22 have higher external quantum efficiencies than Comparative Examples 8 to 9 using the same light emitting layer. That is, as can be seen with reference to Table 5, in Examples 15 to 22 in which the B-type crystal or C-type crystal of the compound ET-1 is used as the electron-injected material, the D-type of the compound ET-1 is used as the electron-injected material. Compared with Comparative Examples 8 to 11 in which crystalline or amorphous materials are used, it is possible to obtain a light emitting element in which the external quantum efficiency is significantly improved regardless of which thermally activated delayed fluorescent material is used for the light emitting layer. all right.

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

(Example 23)
A glass substrate (manufactured by Geomatec Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited at 165 nm was cut into a size of 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with "Semicoclean 56" (trade name, manufactured by Furuuchi 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 the device was manufactured, placed in a vacuum vapor deposition apparatus, and evacuated ^{until the degree of vacuum in the apparatus became 5 × 10 -4} Pa or less. By the resistance heating method, HAT-CN6 was first deposited at 5 nm as a hole injection layer, and then HT-1 was deposited at 50 nm as a hole transport layer. Next, as the light emitting layer, H-1 which is a host material, compound D-1 which is a dopant compound, and compound H-2 which is a TADF material are arranged in a weight ratio of 80: 1: 19. , 20 nm thick vapor deposition. Further, as the electron transport layer, compound ET-2 is used as the electron transport material and 2E-1 is used as the donor material, and the vapor deposition rate ratio of the compounds ET-2 and 2E-1 is 1: 1 so that the thickness is 35 nm. It was laminated on the surface. Subsequently, a phenanthroline derivative ET-1 crystal (C-type crystal: Example 6) was used as the n-type charge generation layer for the n-type host, metallic lithium was used for the n-type dopant, and the compound ET-1 and metallic lithium were used. The layers were laminated at 10 nm so that the vapor deposition rate ratio was 99: 1. Further, HAT-CN6 was laminated at 10 nm as a p-type charge light emitting layer. A hole transport layer of 50 nm, a light emitting layer of 20 nm, and an electron transport layer of 35 nm were deposited on the hole in this order in the same manner as described above. Next, after depositing 2E-1 at 0.5 nm as an electron injection layer, magnesium and silver were co-deposited at 1000 nm to serve as a cathode, and a 5 × 5 mm square tandem fluorescent light emitting element was produced.

The external quantum efficiency when this light emitting device was made to emit light at ^{1000 cd / m 2 was 16.2%.} It was confirmed that the external quantum efficiency was improved as compared with Example 15 in which the light emitting layer was only one layer.

(Example 24)
A glass substrate (manufactured by Geomatec Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited at 165 nm was cut into a size of 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with "Semicoclean 56" (trade name, manufactured by Furuuchi 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 the device was manufactured, placed in a vacuum vapor deposition apparatus, and evacuated ^{until the degree of vacuum in the apparatus became 5 × 10 -4} Pa or less. By the resistance heating method, HAT-CN6 was first deposited at 5 nm as a hole injection layer, and then HT-1 was deposited at 50 nm as a hole transport layer. Next, as the light emitting layer, H-1 which is a host material, compound D-6 which is a dopant material, and compound H-3 which is a TADF material are arranged in a weight ratio of 80: 1: 19. , 30 nm thick vapor deposition. Crystals (C-type crystals) of ET-1, which is a phenanthroline derivative, were laminated to a thickness of 35 nm as an electron transport layer. Subsequently, as an n-type charge generation layer, a crystal of ET-1 which is a phenanthroline derivative which is an n-type host (C-type crystal:
Example 6) and metallic lithium, which is an n-type dopant, were laminated at 10 nm so that the vapor deposition rate ratio was 99: 1. Further, HAT-CN6 was laminated at 10 nm as a p-type charge generation layer. Similarly to the above, a hole transport layer of 50 nm, a light emitting layer of 30 nm, and ET-1 (C-type crystal) of 35 nm as an electron transport layer were deposited in this order. Next, after depositing 2E-1 at 0.5 nm as an electron injection layer, magnesium and silver were co-deposited at 1000 nm to serve as a cathode, and a tandem type light emitting element of 5 mm × 5 mm square was produced.

The external quantum efficiency was 11.3% when this light emitting device was ^{made to emit light at 1000 cd / m 2.} It was confirmed that the external quantum efficiency was improved as compared with Example 11 in which the light emitting layer was only one layer.

The crystal of the phenanthroline derivative of the present invention exhibits extremely high chemical purity as compared with the phenanthroline derivative obtained by the conventional method, and since the amount of residual solvent is small, bumping in sublimation purification can be suppressed, which is suitable for industrial production. Is also available. Further, since the phenanthroline derivative obtained by sublimating and purifying the crystal of the phenanthroline derivative of the present invention has high chemical purity, it has a display element, a flat panel display, a backlight, lighting, an interior, a sign, a signboard, an electronic camera, and an optical signal generator. It can be suitably used as a light emitting element material used in such fields.

Claims

It has a structure represented by the general formula (1), and in powder X-ray diffraction, the diffraction angles 2θ (°) 5.0 ± 0.2, 7.5 ± 0.2, 8.7 ± 0.2, Crystals of a phenanthroline derivative having peaks at 12.5 ± 0.2 and 17.3 ± 0.2, respectively.

(In the general formula (1), X represents a phenylene group or a naphthylene group.)
The crystal of the phenanthroline derivative according to claim 1, wherein the phenanthroline derivative is 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene.
The crystal of the phenanthroline derivative according to claim 1 or 2, which has an endothermic peak in the range of 243 to 247 ° C. in the simultaneous measurement of differential thermogravimetric analysis.
It is selected from the group consisting of an anode and a cathode, a light emitting layer containing a thermally activated delayed fluorescent material between the cathode and the cathode, an electron transport layer, an electron injection layer and a charge generation layer, and claim 1. A light emitting element that emits light by electric energy and has at least one layer containing a phenanthroline derivative derived from the crystal according to any one of 3 to 3.
The light emitting device according to claim 4, further comprising a pyrromethene boron complex represented by the following general formula (2) in the light emitting layer.

(Here, in the above general formula (2),
X 1 is a nitrogen atom or a carbon atom, where the carbon atom is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or substituted or Unsubstituted alkoxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted alkenyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted. Substituted heteroaryl group, halogen atom, carboxy group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted amino group, nitro group, cyano group, substituted or unsubstituted silyl group , And one atomic or monovalent group selected from the group consisting of substituted or unsubstituted siloxanyl groups are attached.
R 1 to R 6 are independently hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted aryl group, alkoxy group, substituted or unsubstituted alkylthio group, respectively. Substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aralkyl group, substituted or unsubstituted heteroaryl group, halogen atom, carboxy group, substituted or Select from the group consisting of an 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 siroxanyl group. An atom or group to be formed, provided that in any one or more of the R 1 and R 2 pairs, the R 2 and R 3 pairs, the R 4 and R 5 pairs, and the R 5 and R 6 pairs. A ring may be formed by forming a bond between the groups constituting the set.
Z 1 and Z 2 are independently halogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups, substituted or unsubstituted alkoxy groups, cyano groups, and substituted or unsubstituted aryloxy groups, respectively. It is an atom or group selected from the group consisting of, but may be one in which a bond is formed between Z 1 and Z 2 to form a ring. )
In the general formula (2),
When X 1 is carbon, the group bonded to the carbon is a group represented by the following general formula (3).

(Here, R 9 to R 11 are independently hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted alkenyl. Group, substituted or unsubstituted cycloalkenyl group, substituted or unsubstituted alkynyl group, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, hydroxyl group, thiol group, substituted or unsubstituted alkoxy group, substituted Alternatively, an 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 carboxy group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or Unsubstituted carbamoyl group, substituted or unsubstituted alkylsulfonyl group, substituted or unsubstituted arylsulfonyl group, substituted or unsubstituted aminosulfonyl group, substituted or unsubstituted amino group, nitro group, substituted or unsubstituted silyl An atom or group selected from the group consisting of a ring structure formed between a group and an adjacent group.
R 7 and R 8 are groups independently selected from the group consisting of substituted or unsubstituted alkyl groups, substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups, respectively. )
Z 1 and Z 2 are independently substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryloxy groups, substituted or unsubstituted aryl groups, halogen atoms, and cyano groups, respectively. It is a group selected from the group consisting of
R 1 , R 3 , R 4 and R 6 are independently substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups, respectively.
(Here, these aryl groups and heteroaryl groups may be monocyclic or fused rings. However, when one or both of R 1 and R 6 are monocyclic aryl groups and heteroaryl groups, the monocyclic ring Does the aryl group and heteroaryl group 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, it has a total of two or more methyl groups and primary alkyl groups as substituents.)
R 2 and R 5 are independently hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, substituted or unsubstituted. Substituted heteroaryl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted alkylthio groups, substituted or unsubstituted aryloxy groups, substituted or unsubstituted arylthio groups, halogen atoms, cyano groups, carboxy groups, substituted or An atom or group selected from the group consisting of an 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.
(Here, in one or both of the pair of R 4 and R 5 and the pair of R 2 and R 3 , a bond is formed between the groups constituting the pair to form a ring having five or more members. It may be the one.)
The light emitting element according to claim 5.
In the general formula (2),
When X 1 is carbon, the group bonded to the carbon is a group represented by the following general formula (4).

(Here, R 12 to R 14 are independently hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted heterocyclic group, substituted or unsubstituted alkenyl. Group, substituted or unsubstituted cycloalkenyl group, substituted or unsubstituted alkynyl group, hydroxyl group, thiol group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted aryloxy group, substituted Alternatively, an unsubstituted 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, a carboxy group, a substituted or unsubstituted alkoxycarbonyl group, a 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, An atom or group selected from the group consisting of a nitro group, a substituted or unsubstituted silyl group, a substituted or unsubstituted siroxanyl group, a substituted or unsubstituted boryl group and a substituted or unsubstituted phosphine oxide group.
R 15 is 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 Substituent alkynyl group, hydroxyl group, thiol 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, carboxy group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted carbamoyl group, substituted or unsubstituted alkylsulfonyl group , Substituent 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 A group selected from the group consisting of a substituted siloxanyl group, a substituted or unsubstituted boryl group and a substituted or unsubstituted phosphine oxide group.
Ar 1 is a group selected from the group consisting of substituted or unsubstituted aryl groups or substituted or unsubstituted heteroaryl groups. )
Z 1 and Z 2 are independently substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryloxy groups, substituted or unsubstituted aryl groups, halogen atoms, and cyano groups, respectively. An atom or group selected from the group consisting of
R 1 to R 6 are independently hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted. Alkylthio groups, substituted or unsubstituted aryloxy groups, substituted or unsubstituted aryl groups, substituted or unsubstituted heteroaryl groups, substituted or unsubstituted amino groups, substituted or unsubstituted silyl groups, and substituted or unsubstituted. A group selected from the group consisting of substituted siloxanyl groups, provided that at least one of R 1 , R 3 , R 4 , and R 6 is a hydrogen atom or a substituted or unsubstituted alkyl group.
The light emitting element according to claim 5.
The light emitting element according to any one of claims 4 to 7, wherein the light emitting element has a charge generating layer, and the charge generating layer further contains an alkali metal or an alkali metal compound.
The light emitting element according to claim 8, wherein the alkali metal element constituting the alkali metal or alkali metal compound is lithium.
A display device including the light emitting element according to any one of claims 4 to 9.
A lighting device including the light emitting element according to any one of claims 4 to 9.
The phenanthroline derivative represented by the general formula (1) is dissolved in a mixed solvent containing an aprotic polar solvent and an aromatic solvent and crystallized, and then the crystals obtained by the step (I). The method for producing a crystal of a phenanthroline derivative according to any one of claims 1 to 3, which comprises a step (III) of drying the phenanthroline derivative at 50 ° C. or higher.
It has a structure represented by the general formula (1), and in powder X-ray diffraction, the diffraction angles 2θ (°) 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2. The phenanthroline derivative according to any one of claims 1 to 3, further comprising a step of transferring a crystal of the phenanthroline derivative having peaks at 20.0 ± 0.2 and 23.6 ± 0.2 to a crystal polymorphism. Crystal manufacturing method.
It has a structure represented by the general formula (1), and in powder X-ray diffraction, the diffraction angles 2θ (°) 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2. As the crystals of the phenanthroline derivative having peaks at 20.0 ± 0.2 and 23.6 ± 0.2, those having endothermic peaks in the range of 94 to 98 ° C. in the differential thermal weight simultaneous measurement are used. The method for producing a crystal of a phenanthroline derivative according to claim 13.
The phenanthroline derivative represented by the general formula (1) is dissolved in a mixed solvent containing an aprotonic polar solvent and an aromatic solvent and crystallized, and then the crystals obtained by the step (I). In the powder X-ray diffraction, the diffraction angles 2θ (°) 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2, The method for producing a crystal of a phenanthroline derivative according to claim 13 or 14, wherein a crystal of the phenanthroline derivative having peaks at 20.0 ± 0.2 and 23.6 ± 0.2, respectively, is produced.
It has a structure represented by the following general formula (1), and in powder X-ray diffraction, the diffraction angles 2θ (°) 5.2 ± 0.2, 7.0 ± 0.2, 16.4 ± 0.2. Crystals of phenanthroline derivatives having peaks at 2, 0.0 ± 0.2 and 23.6 ± 0.2, respectively.

(In the general formula (1), X represents a phenylene group or a naphthylene group.)
It has a structure represented by the following general formula (1), and in powder X-ray diffraction, the diffraction angles 2θ (°) 6.7 ± 0.2, 8.2 ± 0.2, 13.7 ± 0.2. , Crystals of phenanthroline derivatives having peaks at 17.7 ± 0.2 and 22.2 ± 0.2, respectively.

(In the general formula (1), X represents a phenylene group or a naphthylene group.)
The crystal of the phenanthroline derivative according to claim 17, wherein the phenanthroline derivative is 1,3-bis (9-phenyl-1,10-phenanthroline-2-yl) benzene.
The crystal of the phenanthroline derivative according to claim 17 or 18, which has an endothermic peak in the range of 180 to 184 ° C. in the differential thermogravimetric simultaneous measurement.
The phenanthroline derivative represented by the general formula (1) is dissolved in a mixed solvent containing an aprotic polar solvent and an aromatic solvent and crystallized, and then the crystals obtained by the step (I). The method for producing a crystal of a phenanthroline derivative according to any one of claims 17 to 19, which comprises a step (II) of dissolving the substance in an ether solvent and crystallizing the substance.