JP2008078362A - Light emitting element material and light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly efficient light emitting element material which is excellent in durability and a light emitting element using it. <P>SOLUTION: The light emitting element material contains pyrene compound expressed by a general formula (1). R<SP>1</SP>to R<SP>17</SP>are hydrogen; alkyl group or the like; Ar<SP>1</SP>to Ar<SP>3</SP>are arylene group or heteroarylene group or the like; X is single bond; n is an integer of 1 to 4. Any n numbers of R<SP>10</SP>to R<SP>17</SP>are used for connection with X. At least one of R<SP>3</SP>and R<SP>5</SP>is aryle group or heteroaryle group, or R<SP>4</SP>is alkyl group or cycloalkyl group. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light-emitting element material useful as a fluorescent dye or a charge transport material and a light-emitting element using the same, and includes a display element, a flat panel display, a backlight, illumination, an interior, a sign, a signboard, an electrophotographic machine, and light The present invention relates to a light-emitting element that can be used in a field such as a signal generator.

  In recent years, research on organic thin-film light-emitting devices that emit light when electrons injected from a cathode and holes injected from an anode are recombined in an organic light-emitting body sandwiched between both electrodes has been actively conducted. This light-emitting element is characterized by thin light emission with high luminance under a low driving voltage and multicolor light emission by selecting a light-emitting material.

This study was conducted by Eastman Kodak's C.I. W. Since Tang et al. Have shown that organic thin-film light-emitting elements emit light with high brightness, many research institutions have studied. A typical structure of the organic thin-film light-emitting device presented by the Kodak research group is a hole-transporting diamine compound, a light-emitting layer of tris (8-quinolinolato) aluminum (III), and a cathode. As described above, Mg: Ag (alloy) was sequentially provided, and green light emission of 1,000 cd / m ² was possible with a driving voltage of about 10 V (see Non-Patent Document 1).

  In addition, organic thin-film light-emitting elements can be obtained in various emission colors by using various fluorescent materials for the light-emitting layer, and therefore, researches for practical application to displays and the like are actively conducted. Among the three primary color luminescent materials, research on the green luminescent material is the most advanced, and at present, intensive research is being conducted to improve the characteristics of the red and blue luminescent materials.

One of the biggest problems in organic thin-film light-emitting elements is to make the light-emitting efficiency and durability of the element compatible. In particular, with respect to blue light-emitting elements, there are few blue light-emitting materials that provide elements with excellent durability and high reliability. For example, a technique using a pyrene compound for a blue light emitting element is disclosed. Blue light emitting devices using aryl-substituted pyrene (see Patent Documents 1 to 7) and amine-substituted pyrene (see Patent Documents 8 and 9) have been reported, but all of them have insufficient durability.
JP 2000-273056 A (Claims 1 and 2) JP 2001-118682 A (Claim 1) JP 2002-63988 A (Claim 1) JP 2003-272864 A (Claim 1) JP 2004-75567 A (Claims 1 to 4) JP 2004-139957 A (Claim 1) International Publication No. 2004/096945 (Patents) JP 2004-204238 A (Claims) International Patent Publication No. 2004/083162 (Claims 1 to 9) Applied Physics Letters (USA) 1987, 51, 12, 913-915

  As described above, the conventional organic thin-film light-emitting element has not been provided with a blue light-emitting element having high luminous efficiency and excellent durability. Accordingly, an object of the present invention is to solve the problems of the prior art, and to provide a light emitting element material that enables a blue light emitting element with high luminous efficiency and excellent durability, and a light emitting element using the same. .

  The present invention is a light emitting device material containing a pyrene compound represented by the general formula (1).

(Here, R ^{1 to} R ¹⁷ may be the same as or different from each other, and hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group, hetero An aryl group, an amino group, a silyl group, or a phosphine oxide group is selected, R ^{1 to} R ¹⁷ may form a ring with adjacent substituents, and Ar ^{1 to} Ar ³ are an arylene group or a heteroarylene group. Ar ² and Ar ³ may be bonded to form a ring, X is selected from a single bond, an arylene group, and a heteroarylene group, n is an integer of 1 to 4. R ¹⁰ Any one of ˜R ¹⁷ is used for linking with X, provided that at least one of R ³ and R ⁵ is an aryl group or a heteroaryl group; R ⁴ is an alkyl group or a cycloalkyl group.)
Further, the present invention is a light-emitting element in which at least a light-emitting layer exists between an anode and a cathode and emits light by electric energy, and the light-emitting layer contains a light-emitting element material represented by the general formula (1). It is a light emitting element characterized by these.

  INDUSTRIAL APPLICATION This invention can be utilized for a light emitting element etc., and can provide the light emitting element material excellent in thin film stability. Furthermore, a light emitting device having high luminous efficiency and excellent durability can be obtained.

  The pyrene compound represented by the general formula (1) in the present invention will be described in detail.

Here, R ^{1 to} R ¹⁷ may be the same as or different from each other, and hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group, heteroaryl Selected from a group, an amino group, a silyl group, and a phosphine oxide group. R ^{1 to} R ¹⁷ may form a ring with adjacent substituents. Ar ^{1 to} Ar ³ are an arylene group or a heteroarylene group, and Ar ² and Ar ³ may be bonded to form a ring. X is selected from a single bond, an arylene group, and a heteroarylene group. n is an integer of 1-4. Any n of R ^{10 to} R ¹⁷ are used for connection with X. However, at least one of R ³ and R ⁵ is an aryl group or a heteroaryl group, or R ⁴ is an alkyl group or a cycloalkyl group.

  Among these substituents, the alkyl group is, for example, 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, or a tert-butyl group. This may or may not have a substituent. There is no restriction | limiting in particular in the additional substituent in the case of being substituted, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned, This point is common also in the following description. The number of carbon atoms of the alkyl group is not particularly limited, but is usually in the range of 1 to 20 and more preferably 1 to 8 from the viewpoint of availability and cost.

  The cycloalkyl group represents a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclohexyl, norbornyl, adamantyl, etc., which may or may not have a substituent. Although carbon number of an alkyl group part is not specifically limited, Usually, it is the range of 3-20.

  The heterocyclic group refers to an aliphatic ring having atoms other than carbon, such as a pyran ring, a piperidine ring, and a cyclic amide, in the ring, which may or may not have a substituent. . Although carbon number of a heterocyclic group is not specifically limited, Usually, it is the range of 2-20.

  The alkoxy group refers to, for example, a functional group having an aliphatic hydrocarbon group bonded through an ether bond such as a methoxy group, an ethoxy group, or a propoxy group, and the aliphatic hydrocarbon group may have a substituent. It may not have. Although carbon number of an alkoxy group is not specifically limited, Usually, it is the range of 1-20.

  The alkylthio group is a group in which an oxygen atom of an ether bond of an alkoxy group is substituted with a sulfur atom. The hydrocarbon group of the alkylthio group may or may not have a substituent. Although carbon number of an alkylthio group is not specifically limited, Usually, it is the range of 1-20.

  An aryl ether group refers to a functional group to which an aromatic hydrocarbon group is bonded via an ether bond, such as a phenoxy group, and the aromatic hydrocarbon group may or may not have a substituent. Good. Although carbon number of an aryl ether group is not specifically limited, Usually, it is the range of 6-40.

  An aryl thioether group is one in which the oxygen atom of the ether bond of the aryl ether group is substituted with a sulfur atom. The aromatic hydrocarbon group in the aryl ether group may or may not have a substituent. Although carbon number of an aryl ether group is not specifically limited, Usually, it is the range of 6-40.

  An aryl group refers to an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, or a pyrenyl group. The aryl group may or may not have a substituent. Although carbon number of an aryl group is not specifically limited, Usually, it is the range of 6-40.

  A heteroaryl group refers to an aromatic group having a non-carbon atom in the ring, such as a furanyl group, a thiophenyl group, an oxazolyl group, a pyridyl group, a quinolinyl group, or a carbazolyl group, which has a substituent. Even if it does not have. Although carbon number of a heteroaryl group is not specifically limited, Usually, it is the range of 2-30.

  A silyl group refers to, for example, a functional group having a bond to a silicon atom, such as a trimethylsilyl group, which may or may not have a substituent. Although carbon number of a silyl group is not specifically limited, Usually, it is the range of 3-20. Moreover, the number of silicon is 1-6 normally.

An arylene group refers to a divalent group derived from an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, or a pyrenyl group, which may have a substituent. It may not have. Although carbon number of an arylene group is not specifically limited, Usually, it is the range of 6-40. When Ar ^{1 to} Ar ^{3 in} the general formula (1) are an arylene group, the arylene group may or may not have a substituent, but the number of carbons including the substituent is 6 to 12 It is a range.

  The heteroarylene group is a 6-membered aromatic group having one or more atoms other than carbon, such as a pyridyl group, a quinolinyl group, a pyrazinyl group, or a naphthyridyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a carbazolyl group. 2 represents a divalent group derived from a group, which may or may not have a substituent. Although carbon number of heteroarylene group is not specifically limited, Usually, it is the range of 2-30.

When the adjacent substituents form a ring, any adjacent two substituents (for example, R ¹ and R ^{2 in} formula (1)) can be bonded to each other to form a conjugated or non-conjugated condensed ring. As a constituent element of the condensed ring, in addition to carbon, nitrogen, oxygen, sulfur, phosphorus and silicon atoms may be contained, or further condensed with another ring.

  The pyrene compound represented by the general formula (1) of the present invention has excellent heat resistance and high charge transportability by having a pyrene skeleton and a condensed carbazole group in the molecule. Furthermore, since the aromatic amine is connected to the carbazole structure, the hole injection property and the hole transport property from the metal electrode or the organic thin film layer are particularly excellent, and high efficiency can be obtained. In addition, since it has excellent hole injection property and hole transport property, when used in combination with an electron transport layer made of an electron transport material having high electron transport ability, It is easy to maintain the balance and the life of the light emitting element is prolonged. In addition, since the balance is realized while maintaining a high charge transport capability, it is possible to achieve both a low driving voltage and a long life.

The pyrene compound represented by the general formula (1) of the present invention has a pyrene compound in which at least one of R ³ and R ⁵ is an aryl group or a heteroaryl group, or R ⁴ is an alkyl group or a cycloalkyl group. Intermolecular interaction between skeletons is suppressed, and a stable thin film can be formed. Among these, when R ⁴ is an alkyl group or a cycloalkyl group, it is preferable that R ⁸ is an aryl group or a heteroaryl group, because intermolecular interaction is further suppressed and a more stable thin film can be formed. In addition, since the synthesis process is easy and the cost can be reduced, it is preferable that R ⁵ is an aryl group and at least one of X is linked at the position of R ¹¹ or R ¹² . Although it does not specifically limit as said pyrene compound, Specifically, the following examples are given.

  A known method can be used for the synthesis of the pyrene compound represented by the general formula (1). Examples of the method for introducing a carbazolyl group into the pyrene skeleton include a method using a coupling reaction of a halogenated pyrene derivative and a carbazole or carbazolyl aryl metal complex under a palladium or nickel catalyst, or a pyrenyl metal under a palladium or nickel catalyst. A method using a coupling reaction between a complex and a halogenated carbazole derivative is exemplified, but the method is not limited thereto.

  Next, embodiments of the light-emitting element in the present invention will be described in detail with examples. The light emitting device of the present invention comprises at least an anode and a cathode, and an organic layer made of a light emitting device material interposed between the anode and the cathode.

  The anode used in the present invention is not particularly limited as long as it can efficiently inject holes into the organic layer, but it is preferable to use a material having a relatively large work function. For example, tin oxide, indium oxide, zinc oxide Conductive metal oxides such as indium and indium tin oxide (ITO), metals such as gold, silver and chromium, inorganic conductive materials such as copper iodide and copper sulfide, conductive polymers such as polythiophene, polypyrrole and polyaniline, etc. Is mentioned. These electrode materials may be used alone, or a plurality of materials may be laminated or mixed.

  The resistance of the anode is not limited as long as a current sufficient for light emission of the light emitting element can be supplied. For example, an ITO substrate of 300Ω / □ or less functions as an element electrode, but since it is now possible to supply a substrate of about 10Ω / □, use a low-resistance product of 100Ω / □ or less. Is particularly desirable. The thickness of ITO can be arbitrarily selected according to the resistance value, but is usually used in a range of 100 to 300 nm.

In order to maintain the mechanical strength of the light emitting element, the light emitting element is preferably formed over a substrate. As the substrate, a glass substrate such as soda glass or non-alkali glass is preferably used. As the thickness of the glass substrate, it is sufficient that the thickness is sufficient to maintain the mechanical strength. The glass material is preferably alkali-free glass because it is better to have less ions eluted from the glass, but soda lime glass with a barrier coat such as SiO ₂ is also available on the market. it can. Furthermore, if the anode functions stably, the substrate does not have to be glass. For example, the anode may be formed on a plastic substrate. The ITO film forming method is not particularly limited, such as an electron beam method, a sputtering method, and a chemical reaction method.

    The material used for the cathode used in the present invention is not particularly limited as long as it is a substance that can efficiently inject electrons into the organic layer, but is generally platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium. Lithium, sodium, potassium, cesium, calcium and magnesium, and alloys thereof. Lithium, sodium, potassium, cesium, calcium, magnesium, or alloys containing these low work function metals are effective for increasing the electron injection efficiency and improving device characteristics. However, since these low work function metals are generally unstable in the atmosphere, the organic layer is doped with a small amount of lithium or magnesium (1 nm or less on a vacuum deposition film thickness meter) and stable. A preferred example is a method for obtaining a high electrode. Also, an inorganic salt such as lithium fluoride can be used. Furthermore, for electrode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, inorganic substances such as silica, titania and silicon nitride, polyvinyl alcohol, polyvinyl chloride Lamination of organic polymer compounds such as hydrocarbon polymer compounds is a preferred example. The method for producing these electrodes is not particularly limited as long as conduction can be achieved, such as resistance heating, electron beam, sputtering, ion plating, and coating.

  The light-emitting element of the present invention is formed of a light-emitting element material in which the organic layer contains a pyrene compound represented by the general formula (1). The light-emitting element material corresponds to either a compound that emits light by itself or a compound that assists the light emission, and refers to a compound that participates in light emission. Specifically, a hole-transport material, a light-emitting material, and an electron This includes transportation materials.

    The organic layer constituting the light emitting element of the present invention is composed of a light emitting layer having at least a light emitting element material. Examples of the organic layer include, in addition to a structure composed of only a light emitting layer, 1) a hole transport layer / light emitting layer / electron transport layer, 2) a light emitting layer / electron transport layer, and 3) a hole transport layer / light emitting layer. And the like. Each of the layers may be a single layer or a plurality of layers. When the hole transport layer and the electron transport layer have a plurality of layers, the layers in contact with the electrodes may be referred to as a hole injection layer and an electron injection layer, respectively. In the material, the electron injection material is included in the electron transport material.

  The hole transport layer is formed by a method of laminating or mixing one or more hole transport materials or a method using a mixture of a hole transport material and a polymer binder. Alternatively, the hole transport layer may be formed by adding an inorganic salt such as iron (III) chloride to the hole transport material. The hole transport material is not particularly limited as long as it is a compound that forms a thin film necessary for manufacturing a light emitting element, can inject holes from the anode, and can further transport holes. For example, 4,4′-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl, 4,4 Triphenylamine derivatives such as', 4 "-tris (3-methylphenyl (phenyl) amino) triphenylamine, biscarbazole derivatives such as bis (N-allylcarbazole) or bis (N-alkylcarbazole), pyrazoline derivatives, Heterocyclic compounds such as stilbene compounds, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives, and polymers, polycarbonates, styrene derivatives, polythiophene, polyaniline having the above monomers in the side chain , Polyfluorene, poly Such alkenyl carbazole and polysilane are preferred.

  In the present invention, the light emitting layer may be either a single layer or a plurality of layers, and the light emitting material of each layer may be a single material or a mixture of a plurality of materials (host material, dopant material). From the viewpoint of lifetime, a mixture of a host material and a dopant material that can separate the functions of film formation, hole / electron transport, and light emission is preferable. That is, in the light emitting element of the present invention, in each light emitting layer, only one of the host material and the dopant material may emit light, or both the host material and the dopant material may emit light. Each of the host material and the dopant material may be one kind or a plurality of combinations. The dopant material may be included in the entire light emitting layer, or may be partially included. If the amount of the dopant material is too large, a concentration quenching phenomenon occurs, so that it is preferably used at 20% by weight or less, more preferably 10% by weight or less with respect to the host material. The doping method can be formed by a co-evaporation method with a host material, but may be pre-mixed with the host material and then simultaneously deposited.

  The pyrene compound represented by the general formula (1) may be used as a hole transport material or an electron transport material, but is preferably used as a light emitting material because it has high light emission performance. The light-emitting element material of the present invention is preferably used as a blue light-emitting material because it exhibits strong light emission in the blue region, but can also be used as a material for green to red light-emitting elements and white light-emitting elements. Although the pyrene compound of this invention may be used as a dopant material, since it is excellent in thin film stability, it is used suitably as a host material.

  The ionization potential of the pyrene compound represented by the general formula (1) of the present invention is not particularly limited, but is preferably 4.6 eV or more and 6.2 eV or less, and more preferably 4.8 eV or more and 6.0 eV or less. . Although the absolute value of the ionization potential may vary depending on the measurement method, the ionization potential in the present invention is an ITO glass substrate using an atmospheric-type ultraviolet photoelectron analyzer (AC-1, manufactured by Riken Kikai Co., Ltd.). It is the value which measured the thin film vapor-deposited on the thickness of 30 nm-100 nm on the top.

  The host material used in the present invention need not be limited to one kind of pyrene compound represented by the general formula (1) of the present invention, and a plurality of pyrene compounds of the present invention may be mixed and used. One or more kinds may be used as a mixture with the pyrene compound of the present invention. Examples of the host material that can be mixed include condensed ring derivatives such as anthracene and perylene which are luminescent materials, N, N′-dinaphthyl-N, N′-diphenyl-4,4′-diphenyl-1,1′-diamine, and the like. Aromatic amine derivatives, metal chelated oxinoid compounds such as tris (8-quinolinato) aluminum (III), bisstyryl derivatives such as distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, For pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadiazole derivatives, carbazole derivatives, pyrrolopyrrole derivatives, polymers, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazo Le derivative, polythiophene derivative is preferably used.

  The dopant material contained in the light-emitting material is not particularly limited, but a compound having an aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, triphenylene, perylene, fluorene, indene, or a derivative thereof (for example, 2- (benzothiazole-2- Yl) -9,10-diphenylanthracene and 5,6,11,12-tetraphenylnaphthacene), furan, pyrrole, thiophene, silole, 9-silafluorene, 9,9'-spirobisilafluorene, benzothiophene , Benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, thioxanthene, etc. Aminostyryl such as zen derivatives, 4,4′-bis (2- (4-diphenylaminophenyl) ethenyl) biphenyl, 4,4′-bis (N- (stilben-4-yl) -N-phenylamino) stilbene Derivatives, aromatic acetylene derivatives, tetraphenylbutadiene derivatives, stilbene derivatives, aldazine derivatives, pyromethene derivatives, diketopyrrolo [3,4-c] pyrrole derivatives, 2,3,5,6-1H, 4H-tetrahydro-9- (2 Coumarin derivatives such as' -benzothiazolyl) quinolidino [9,9a, 1-gh] coumarin, azole derivatives such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, triazole and metal complexes thereof and N, N'-diphenyl -N, N'-di (3-methyl And aromatic amine derivatives typified by phenyl) -4,4'-diphenyl-1,1'-diamine. Among them, it is preferable to use a condensed aromatic ring derivative having an electron-accepting substituent as a dopant because the effect of the thin film stability of the pyrene compound of the present invention becomes more remarkable. Specifically, pyrene compounds having a benzoazole group typified by 1- (benzoxazol-2-yl) -3,8-bis (4-methylphenyl) pyrene are particularly preferable dopants.

  In the present invention, the electron transport layer is a layer in which electrons are injected from the cathode and further transports electrons. The electron transport layer has high electron injection efficiency, and it is desired to efficiently transport injected electrons. Therefore, it is desirable that the electron transport layer is made of a material having a high electron affinity, a high electron mobility, excellent stability, and a trapping impurity that is unlikely to be generated during manufacture and use. However, considering the transport balance between holes and electrons, if the electron transport layer mainly plays a role of effectively preventing the holes from the anode from recombining and flowing to the cathode side, the electron transport Even if it is made of a material that does not have a high capability, the effect of improving the luminous efficiency is equivalent to that of a material that has a high electron transport capability. Therefore, the electron transport layer in the present invention includes a hole blocking layer that can efficiently block the movement of holes as the same meaning.

  Examples of the electron transport material used in the electron transport layer include condensed polycyclic aromatic derivatives such as naphthalene and anthracene, styryl aromatic ring derivatives represented by 4,4′-bis (diphenylethenyl) biphenyl, anthraquinone, diphenoquinone, and the like. Quinoline derivatives, phosphorus oxide derivatives, quinolinol complexes such as tris (8-quinolinolato) aluminum (III), benzoquinolinol complexes, hydroxyazole complexes, azomethine complexes, tropolone metal complexes and flavonol metal complexes. A compound having a heteroaryl ring structure composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus and containing electron-accepting nitrogen, because driving voltage is reduced and high-efficiency light emission is obtained. Is preferably used.

  The electron-accepting nitrogen in the present invention represents a nitrogen atom that forms a multiple bond with an adjacent atom. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron accepting property. Therefore, a heteroaryl ring containing electron-accepting nitrogen has high electron affinity, excellent electron transport ability, and can be used for an electron transport layer to reduce the driving voltage of a light-emitting element. Heteroaryl rings containing electron-accepting nitrogen include, for example, pyridine ring, pyrazine ring, pyrimidine ring, quinoline ring, quinoxaline ring, naphthyridine ring, pyrimidopyrimidine ring, benzoquinoline ring, phenanthroline ring, imidazole ring, oxazole ring, oxalate ring, Examples include a diazole ring, a triazole ring, a thiazole ring, a thiadiazole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, and a phenanthrimidazole ring.

  Examples of these compounds having a heteroaryl ring structure include benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoins. Preferred compounds include quinoline derivatives, oligopyridine derivatives such as bipyridine and terpyridine, quinoxaline derivatives and naphthyridine derivatives. Among them, imidazole derivatives such as tris (N-phenylbenzimidazol-2-yl) benzene, 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 bathocuproine and 1,3-bis (1,10-phenanthroline-9-yl) benzene, 2,2 ′ A benzoquinoline derivative such as bis (benzo [h] quinolin-2-yl) -9,9′-spirobifluorene, 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1, Bipyridine derivatives such as 1-dimethyl-3,4-diphenylsilole, 1,3-bis (4 ′-(2,2 ′: 6′2 ″ -ta Terpyridine derivatives such as pyridinyl)) benzene, naphthyridine derivatives such as bis (1-naphthyl) -4- (1,8-naphthyridin-2-yl) phenylphosphine oxide are preferably used from the viewpoint of electron transporting capability.

  The electron transport material may be used alone, but two or more of the electron transport materials may be mixed and used, or one or more of the other electron transport materials may be mixed and used in the electron transport material. It is also possible to use a mixture with a metal such as an alkali metal or an alkaline earth metal. The ionization potential of the electron transport layer is not particularly limited, but is preferably 5.8 eV or more and 8.0 eV or less, and more preferably 6.0 eV or more and 7.5 eV or less.

  The method of forming each of the above layers constituting the light emitting element is not particularly limited, such as resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination method, coating method, ink jet method, printing method, laser induced thermal transfer method, etc. From this point, resistance heating vapor deposition or electron beam vapor deposition is preferable.

  The thickness of the layer depends on the resistance value of the luminescent material and cannot be limited, but is selected from 1 to 1000 nm. The film thicknesses of the light emitting layer, the electron transport layer, and the hole transport layer are each preferably 1 nm to 200 nm, and more preferably 5 nm to 100 nm.

  The light-emitting element of the present invention has a function of converting electrical energy into light. Here, a direct current is mainly used as the electrical energy, but a pulse current or an alternating current can also be used. The current value and the voltage value are not particularly limited, but should be selected so that the maximum luminance can be obtained with as low energy as possible in consideration of the power consumption and lifetime of the device.

  The light emitting device of the present invention is suitably used as a display for displaying in a matrix and / or segment system, for example.

  In the matrix method, pixels for display are two-dimensionally arranged such as a lattice shape or a mosaic shape, and a character or an image is displayed by a set of pixels. The shape and size of the pixel are determined by the application. For example, a square pixel with a side of 300 μm or less is usually used for displaying images and characters on a personal computer, monitor, TV, and a pixel with a side of mm order for a large display such as a display panel. become. In monochrome display, pixels of the same color may be arranged. However, in color display, red, green, and blue pixels are displayed side by side. In this case, there are typically a delta type and a stripe type. The matrix driving method may be either a line sequential driving method or an active matrix. Although the structure of the line sequential drive is simple, the active matrix may be superior in consideration of the operation characteristics, and it is necessary to use it depending on the application.

  The segment system in the present invention is a system in which a pattern is formed so as to display predetermined information and an area determined by the arrangement of the pattern is caused to emit light. For example, the time and temperature display in a digital clock or a thermometer, the operation state display of an audio device or an electromagnetic cooker, the panel display of an automobile, and the like can be mentioned. The matrix display and the segment display may coexist in the same panel.

  The light emitting device of the present invention is also preferably used as a backlight for various devices. The backlight is used mainly for the purpose of improving the visibility of a display device that does not emit light, and is used for a liquid crystal display device, a clock, an audio device, an automobile panel, a display panel, a sign, and the like. In particular, the light-emitting element of the present invention is preferably used for a backlight for a liquid crystal display device, particularly a personal computer for which a reduction in thickness is being considered, and a backlight that is thinner and lighter than conventional ones can be provided.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited by these Examples. In addition, the number of the compound in each following Example points out the number of the compound described in the above chemical formula. The evaluation method for structural analysis is shown below.

¹ H-NMR was measured with a deuterated chloroform solution using superconducting FTNMR EX-270 (manufactured by JEOL Ltd.).

Example 1
Synthesis of Compound [18] 2-Bromonitrobenzene 10 g, 4-chlorophenylboronic acid 8.5 g, tripotassium phosphate 25.4 g, tetrabutylammonium bromide 3.9 g, palladium acetate 270 mg and dimethylformamide 150 ml were mixed in a nitrogen stream. Under stirring at 130 ° C. for 3 hours. After cooling to room temperature, 100 ml of water was poured and extracted with 150 ml of ethyl acetate. The organic layer was washed twice with 100 ml of water, dried over magnesium sulfate and evaporated. After purification by silica gel column chromatography and vacuum drying, 8.6 g of 2- (4-chlorophenyl) nitrobenzene was obtained.

  2.0 g of 2- (4-chlorophenyl) nitrobenzene, 2.5 g of N-phenyl-1-naphthylamine, 0.99 g of sodium t-butoxy, 0.19 g of (tris-t-butylphosphine) tetrafluoroborate, bis ( A mixed solution of 0.43 g of dibenzylideneacetone) palladium (0) and 30 ml of m-xylene was heated and stirred at 140 ° C. for 5 hours under a nitrogen stream. After cooling to room temperature, the mixture was filtered using celite. The filtrate was evaporated and purified by silica gel column chromatography. After vacuum drying, 1.5 g of 2- {4- (N-phenyl-1-naphthylamino) phenyl} nitrobenzene was obtained.

  1.5 g of 2- {4- (N-phenyl-1-naphthylamino) phenyl} nitrobenzene and 20 ml of triethyl phosphite were heated and stirred at 160 ° C. for 8 hours. After distilling off triethyl phosphite under reduced pressure, 10 ml of methanol was added and filtered. After the solid was vacuum dried, 1.2 g of 2- (N-phenyl-1-naphthylamino) carbazole was obtained.

  A mixed solution of 59 g of 1-bromopyrene, 40 g of p-chlorophenylboronic acid, 108 g of tripotassium phosphate, 16.4 g of tetrabutylammonium bromide, 1.15 g of palladium acetate and 1250 ml of dimethylformamide was heated and stirred at 130 ° C. for 3 hours under a nitrogen stream. did. After cooling to room temperature, 1000 ml of water was poured and filtered. After washing with 200 ml of methanol, the obtained solid was dissolved in 1000 ml of dichloromethane, dried over magnesium sulfate, filtered through celite, and evaporated. After washing with 200 ml of methanol and vacuum drying, 58.2 g of 1- (4-chlorophenyl) pyrene was obtained.

  Next, a mixed solution of 58.2 g of 1- (4-chlorophenyl) pyrene, 36.4 g of N-bromosuccinimide and 1900 ml of dimethylformamide was stirred with heating at 40 ° C. for 6 hours in a nitrogen stream. After cooling to room temperature, 500 ml of water was poured and filtered. After washing with 200 ml of methanol and vacuum drying, a mixture of 1-bromo-6- (4-chlorophenyl) pyrene and 1-bromo-8- (4-chlorophenyl) pyrene was obtained.

  Next, a mixed solution of 1-bromo-6- (4-chlorophenyl) pyrene, 1-bromo-8- (4-chlorophenyl) pyrene and 500 ml of dichloromethane was heated and stirred for 30 minutes while refluxing in a nitrogen stream. After cooling to room temperature with stirring, the mixture was further stirred for 30 minutes, and the precipitate was filtered. A mixed solution of the obtained precipitate and 300 ml of dichloromethane was heated and stirred for 1 hour while refluxing under a nitrogen stream. After cooling to room temperature with stirring, the mixture was further stirred for 30 minutes, and the precipitate was filtered. After vacuum drying, 15 g of 1-bromo-6- (4-chlorophenyl) pyrene was obtained.

  1-bromo-6- (4-chlorophenyl) pyrene 3.5 g, 4-methylphenylboronic acid 1.6 g, tripotassium phosphate 4.9 g, tetrabutylammonium bromide 0.75 g, palladium acetate 52 mg and dimethylformamide 30 ml The mixed solution was heated and stirred at 130 ° C. for 3 hours under a nitrogen stream. After cooling to room temperature, 100 ml of water was poured and filtered. The solid was dissolved in 100 ml of dichloromethane and filtered using celite. The filtrate was evaporated and washed with 30 ml of ethyl acetate. After vacuum drying, 2.6 g of 1- (4-methylphenyl) -6- (4-chlorophenyl) pyrene was obtained.

0.6 g of 1- (4-methylphenyl) -6- (4-chlorophenyl) pyrene, 0.6 g of 2- (N-phenyl-1-naphthylamino) carbazole, 0.17 g of sodium t-butoxy, (Tris-t -Butylphosphine) A mixed solution of 33 mg of tetrafluoroborate, 74 mg of bis (dibenzylideneacetone) palladium (0) and 20 ml of m-xylene was heated and stirred at 140 ° C. for 5 hours under a nitrogen stream. After cooling to room temperature, the mixture was filtered using celite. The filtrate was evaporated and purified by silica gel column chromatography. After vacuum drying, 0.65 g of yellowish white crystals were obtained. The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the yellowish white crystal obtained above was Compound [18].
¹ H-NMR (CDCl ₃ (d = ppm)): 2.51 (s, 3H), 6.99-7.58 (m, 21H), 7.67 (d, 2H), 7.78 (d, 2H), 7.98-8.28 (m, 10h).

This compound [18] was used as a light emitting device material after sublimation purification at about 300 ° C. under a pressure of 1 × 10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area% at a measurement wavelength of 254 nm) was 99.2% before sublimation purification and 99.5% after sublimation purification.

Example 2
Synthesis of Compound [13] The compound [13] was synthesized in the same manner as in Example 1 except that 3-chlorophenylboronic acid was used instead of 4-chlorophenylboronic acid, and 3- (N-phenyl-1-naphthylamino) carbazole 0 .5 g was obtained.

Next, 0.5 g of 1- (4-methylphenyl) -6- (4-chlorophenyl) pyrene, 0.5 g of 3- (N-phenyl-1-naphthylamino) carbazole, 0.17 g of sodium t-butoxy, ( A mixed solution of 33 mg of tris-t-butylphosphine) tetrafluoroborate, 74 mg of bis (dibenzylideneacetone) palladium (0) and 20 ml of m-xylene was heated and stirred at 140 ° C. for 5 hours under a nitrogen stream. After cooling to room temperature, the mixture was filtered using celite. The filtrate was evaporated and purified by silica gel column chromatography. After vacuum drying, 0.55 g of yellowish white crystals were obtained. The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the yellowish white crystal obtained above was Compound [13].
¹ H-NMR (CDCl ₃ (d = ppm)): 2.51 (s, 3H), 6.95-7.65 (m, 21H), 7.67 (d, 2H), 7.78 (d, 2H), 8.01-8.28 (m, 10h).

This compound [13] was used as a light emitting device material after sublimation purification at about 300 ° C. under a pressure of 1 × 10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area% at a measurement wavelength of 254 nm) was 99.3% before sublimation purification and 99.4% after sublimation purification.

Example 3
Synthesis of Compound [30] A mixed solution of 4.1 g of pyrene, 2 g of t-butyl chloride and 33 ml of dichloromethane was cooled to 0 ° C. under a nitrogen stream, and 2.7 g of aluminum chloride was added. The mixed solution was stirred at room temperature for 3 hours, and then 30 ml of water was injected and extracted with 30 ml of dichloromethane. The organic layer was washed twice with 20 ml of water, dried over magnesium sulfate and evaporated. After purification by silica gel column chromatography and vacuum drying, 3 g (content 65%) of 2-t-butylpyrene was obtained.

  Next, 3 g of 2-t-butylpyrene (content 65%), a mixed solution of 50 ml of dichloromethane and 15 ml of methanol was cooled to 0 ° C. under a nitrogen stream, and 3.3 g of benzyltrimethylammonium tribromide dissolved in 10 ml of dichloromethane was added dropwise. did. After stirring this mixed solution at room temperature for 2 hours, 50 ml of water was poured and extracted with 50 ml of dichloromethane. The organic layer was washed twice with 50 ml of water, dried over magnesium sulfate and evaporated. 10 ml of methanol was added to the obtained solid, stirred for 10 minutes, and then filtered. Further, 30 ml of hexane was added and stirred for 30 minutes, followed by filtration. After vacuum drying, 2.3 g of 1-bromo-7-t-butylpyrene was obtained.

  Next, a mixed solution of 2.3 g of 1-bromo-7-t-butylpyrene, 1.1 g of phenylboronic acid, 3.8 g of tripotassium phosphate, 0.58 g of tetrabutylammonium bromide, 12 mg of palladium acetate and 30 ml of dimethylformamide The mixture was heated and stirred at 130 ° C. for 2 hours under a nitrogen stream. After cooling to room temperature, 30 ml of water was injected and extracted with 50 ml of dichloromethane. The organic layer was washed twice with 20 ml of water, dried over magnesium sulfate and evaporated. After purification by silica gel column chromatography and vacuum drying, 1.5 g of 7-t-butyl-1-phenylpyrene was obtained.

  Next, 1.5 g of 7-t-butyl-1-phenylpyrene, 25 ml of dichloromethane and 8 ml of methanol were cooled to 0 ° C. under a nitrogen stream, and 1.7 g of benzyltrimethylammonium tribromide dissolved in 5 ml of dichloromethane was added. It was dripped. After stirring this mixed solution at room temperature for 2 hours, 20 ml of water was injected and extracted with 20 ml of dichloromethane. The organic layer was washed twice with 20 ml of water, dried over magnesium sulfate and evaporated. 10 ml of methanol was added to the obtained solid and left overnight. The precipitated solid was filtered and vacuum-dried to obtain 1.9 g of 1-bromo-7-t-butyl-3-phenylpyrene.

  Next, 1.9 g of 1-bromo-7-t-butyl-3-phenylpyrene, 2.5 g of 4-chlorophenylboronic acid, 2.5 g of tripotassium phosphate, 0.38 g of tetrabutylammonium bromide, 27 mg of palladium acetate, A mixed solution of 40 ml of dimethylformamide was heated and stirred at 130 ° C. for 2 hours under a nitrogen stream. After cooling to room temperature, 40 ml of water was poured and filtered. After washing with 40 ml of methanol, it was purified by silica gel chromatography to obtain 1.5 g of 1- (4-chlorophenyl) -7-tert-butyl-3-phenylpyrene.

Next, 0.6 g of 1- (4-chlorophenyl) -7-t-butyl-3-phenylpyrene, 0.8 g of 2- (N-phenyl-1-naphthylamino) carbazole, 0.17 g of t-butoxy sodium, A mixed solution of 33 mg of (tris-t-butylphosphine) tetrafluoroborate, 74 mg of bis (dibenzylideneacetone) palladium (0) and 20 ml of m-xylene was heated and stirred at 140 ° C. for 5 hours under a nitrogen stream. After cooling to room temperature, the mixture was filtered using celite. The filtrate was evaporated and purified by silica gel column chromatography. After vacuum drying, 0.40 g of yellowish white crystals were obtained. The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the yellowish white crystal obtained above was compound [30].
¹ H-NMR (CDCl ₃ (d = ppm)): 1.61 (s, 9H), 7.30-8.56 (m, 35H).

This compound [30] was used as a light emitting device material after sublimation purification at about 290 ° C. under a pressure of 1 × 10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area% at a measurement wavelength of 254 nm) was 99.5% before sublimation purification and 99.7% after sublimation purification.

Example 4
A light emitting device using the compound [18] was produced as follows. A glass substrate (15 Ω / □, manufactured by Asahi Glass Co., Ltd., electron beam evaporation product) on which an ITO transparent conductive film is deposited to 150 nm is cut to 30 × 40 mm, and the ITO conductive film is patterned by a photolithography method to produce a light emitting portion. And the electrode extraction part was produced. The obtained substrate was ultrasonically washed with acetone, “Semicocrine (registered trademark) 56” (manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes, and then washed with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes and dried. Immediately before the device was fabricated, this substrate was subjected to UV-ozone treatment for 1 hour, further 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, first, copper phthalocyanine was deposited as a hole injecting material at 10 nm, and 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl was deposited as a hole transporting material at 50 nm. Next, the compound [18] was deposited as a host material as a light-emitting material, and D-1 represented by the following formula was deposited as a dopant material to a thickness of 35 nm so that the doping concentration was 2%. Next, as an electron transport material, E-1 represented by the following formula was laminated to a thickness of 20 nm. On the organic layer formed as described above, lithium fluoride was vapor-deposited to a thickness of 0.5 nm, and then aluminum was vapor-deposited with a thickness of 1000 nm to form a 5 × 5 mm square device. The film thickness referred to here is a display value of a crystal oscillation type film thickness monitor. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency blue light emission with a light emission efficiency of 4.5 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 9000 hours.

Examples 5-20
A light emitting device was fabricated in the same manner as in Example 4 except that the materials listed in Table 1 were used as the host material. The results of each example are shown in Table 1.

Comparative Example 1
A light emitting device was produced in the same manner as in Example 4 except that H-1 shown by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , blue light emission with a luminous efficiency of 3.0 lm / W was obtained. When this light emitting device was continuously driven with a direct current of 10 mA / cm ² , the luminance was reduced by half in 500 hours.

Comparative Examples 2-5
A light emitting device was fabricated in the same manner as in Example 4 except that the materials listed in Table 1 were used as the host material. The results of each comparative example are shown in Table 1. In Table 1, H-2, H-3, H-4, and H-5 are compounds represented by the following formula.

Example 21
A light emitting device was produced in the same manner as in Example 4 except that D-2 represented by the following formula was used as a dopant material so that the doping concentration was 2%. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency blue light emission with a light emission efficiency of 5.1 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 12000 hours.

Examples 22-27
A light emitting device was fabricated in the same manner as in Example 4 except that the materials described in Table 2 were used as the host material and the dopant material. The results of each example are shown in Table 2. In Table 2, D-3, D-4, D-5, D-6, D-7, and D-8 are compounds represented by the following formulae.

Example 28
A light emitting device was produced in the same manner as in Example 4 except that E-2 represented by the following formula was used as the electron transport material. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency blue light emission of 4.8 lm / W was obtained. When this light-emitting element was DC-driven at 10 mA / cm ² , the luminance half time was 11000 hours.

Examples 29-34
A light emitting device was produced in the same manner as in Example 4 except that the materials listed in Table 3 were used as the electron transporting material. The results of each example are shown in Table 3. In Table 3, E-3, E-4, E-5, E-6, E-7, and E-8 are compounds represented by the following formulae.

Example 35
A light emitting device was produced in the same manner as in Example 4 except that D-9 represented by the following formula was used as the dopant material so that the doping concentration was 2%. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency green light emission with a luminous efficiency of 5.5 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 4500 hours.

Example 36
A light emitting device was produced in the same manner as in Example 4 except that D-10 represented by the following formula was used as a dopant material so that the doping concentration was 5%. When this light emitting device was DC-driven at 10 mA / cm ² , high efficiency yellow light emission with a light emission efficiency of 5.7 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 10,000 hours.

Example 37
The compound [13] as a host material and the compound [13] as a host material are deposited as a light-emitting material after depositing D-10 as a dopant material to a thickness of 5 nm so that the doping concentration is 5%. Was made in the same manner as in Example 4 except that D-1 was laminated as a dopant material to a thickness of 30 nm so that the doping concentration was 2%. When this light emitting device was DC-driven at 10 mA / cm ² , high-efficiency white light emission with a luminous efficiency of 6.2 lm / W was obtained. When this light emitting device was continuously driven at a direct current of 10 mA / cm ² , the luminance half time was 10,000 hours.

Example 38
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam evaporated product) on which an ITO transparent conductive film is deposited to 150 nm is cut to 30 × 40 mm, and the ITO conductive film is 300 μm pitch (remaining width 270 μm) by photolithography. The pattern was processed into x32 stripes. One side of the ITO stripe in the long side direction is expanded to a pitch of 1.27 mm (opening width 800 μm) in order to facilitate electrical connection with the outside. The obtained substrate was ultrasonically washed with acetone and “Semicocrine (registered trademark) 56” (manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes, respectively, and then washed with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes and dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, further placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, 4,4′-bis (N- (m-tolyl) -N-phenylamino) biphenyl was deposited as a hole transport material by a resistance heating method to a thickness of 150 nm. Next, Compound [13] as a host material and D-1 as a dopant material were vapor-deposited to a thickness of 35 nm so that the doping concentration was 2%. Next, E-1 was laminated to a thickness of 20 nm as an electron transport material. The film thickness referred to here is a display value of a crystal oscillation type film thickness monitor. Next, the mask provided with 16 250 μm openings (corresponding to the remaining width of 50 μm and 300 μm pitch) by wet etching on a 50 μm thick Kovar plate was replaced in a vacuum so as to be orthogonal to the ITO stripe. And it fixed with the magnet from the back so that an ITO board | substrate might closely_contact | adhere. And after doping lithium with a 0.5 nm organic layer, aluminum was vapor-deposited 200 nm, and the 32 * 16 dot matrix element was produced. When this element was driven in matrix, characters could be displayed without crosstalk.

Claims (5)

A light emitting device material comprising a pyrene compound represented by the general formula (1).

(Here, R ^{1 to} R ¹⁷ may be the same as or different from each other, and hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group, hetero An aryl group, an amino group, a silyl group, or a phosphine oxide group is selected, R ^{1 to} R ¹⁷ may form a ring with adjacent substituents, and Ar ^{1 to} Ar ³ are an arylene group or a heteroarylene group. Ar ² and Ar ³ may be bonded to form a ring, X is selected from a single bond, an arylene group, and a heteroarylene group, n is an integer of 1 to 4. R ¹⁰ Any one of ˜R ¹⁷ is used for linking with X, provided that at least one of R ³ and R ⁵ is an aryl group or a heteroaryl group; R ⁴ is an alkyl group or a cycloalkyl group.) The light emitting device material according to claim 1, wherein at least one of X is linked at a position of R ¹¹ or R ¹² . A light emitting device comprising at least a light emitting layer between an anode and a cathode and emitting light by electric energy, wherein the light emitting layer contains the light emitting device material according to claim 1. 3. A light emitting device, wherein the light emitting layer comprises a host material and a dopant material, and the light emitting device material according to claim 1 or 2 is a host material. A heteroaryl ring structure in which at least an electron transport layer exists between the light emitting layer and the cathode, and the electron transport layer is composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus, and contains electron-accepting nitrogen The light emitting device according to claim 3, further comprising a compound having: