JP5821635B2 - Light emitting device material and light emitting device - Google Patents

Description

  The present invention is a light emitting element capable of converting electrical energy into light, and can be used in the fields of display elements, flat panel displays, backlights, lighting, interiors, signs, signboards, electrophotographic machines, optical signal generators, and the like. The present invention relates to a light emitting element.

  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 C.D. W. Since Tang et al. Have shown that organic thin film devices emit light with high brightness, many research institutions have studied.

  In addition, organic thin-film light-emitting elements can be obtained in various light-emitting colors by using various light-emitting materials for the light-emitting layer. 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.

  As a light emitting material, a fluorescent (singlet light emitting) material has been generally used. However, due to the difference in spin multiplicity when electrons and holes are recombined to excite molecules, singlet is used. Since excitons are generated at a ratio of 25% and triplet excitons are generated at a ratio of 75%, it has been attempted to use a phosphorescent (triplet emission) material in order to improve luminous efficiency.

  Therefore, compounds containing a carbazole skeleton have been proposed as host materials having excellent performance when using triplet light-emitting materials as dopant materials (see, for example, Patent Documents 1 and 2). Further, a compound having a triazine skeleton as a substituent for assisting charge injection / transport is used as a host material. (For example, refer to Patent Documents 3 to 4). In addition, materials other than light-emitting materials have been studied. For example, a compound having a carbazole skeleton having a high hole-transporting ability and an excellent electron-blocking ability is used as a hole-transporting material (for example, Patent Document 5). reference).

JP 2003-133075 A JP 2008-135498 A International Publication WO2008 / 56746 Pamphlet International Publication WO2010 / 15306 Pamphlet International Publication WO20111 / 24451 Pamphlet

  However, the organic thin film light emitting element needs to satisfy the improvement of the light emission efficiency, the decrease of the driving voltage, and the improvement of the durability, and it is difficult to satisfy all of these performances particularly for the phosphorescent material.

  An object of the present invention is to provide an organic thin film light emitting device that solves the problems of the prior art and achieves both high luminous efficiency and durability.

The present invention is an element in which one or more layers including at least a light emitting layer exist between an anode and a cathode and emits light by electric energy, and the light emitting layer is represented by a triplet light emitting material and the following general formula (3). a light emitting element, characterized by containing a compound having a carbazole skeleton is.

( R ^{1 to} R ¹⁴ are each hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group, hetero aryl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a silyl group, and -P (= ^O) is selected from ^R 16 ^{R 17} or Ranaru group. ^{R 16} and R ¹⁷ aryl group R ^{1 to} R ¹⁴ may form a ring with adjacent substituents R ¹⁵ is selected from the group consisting of an alkyl group, an aryl group and a heteroaryl group L is a single bond Selected from the group consisting of an arylene group and a heteroarylene group, HAr is an electron-accepting nitrogen; Aromatic heterocyclic groups der having is, a pyridyl group, quinolinyl group, isoquinolinyl group, pyrazinyl group, pyrimidyl group, pyridazinyl group, phenanthrolinyl group, imidazopyridyl group, triazyl group, acridyl group, benzimidazolyl group, Benzookisa Ru is selected from the group consisting of Zoriru group and benzothiazolyl group.)

  According to the present invention, it is possible to provide an organic thin film light emitting device that achieves both high luminous efficiency and durability.

  The compound having a carbazole skeleton represented by the general formula (1) in the present invention will be described in detail.

R ^{31 to} R ³⁸ are each hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group, heteroaryl Group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, silyl group, —P (═O) R ³⁹ R ⁴⁰ and a group represented by the following general formula (2) It is. R ³⁹ and R ⁴⁰ are an aryl group or a heteroaryl group. R ^{31 to} R ³⁸ may form a ring with adjacent substituents. However, any one of R ^{31 to} R ³⁸ is a group represented by the following general formula (2), and is linked to any position of R ^{41 to} R ⁴⁹ in the general formula (2). L is selected from the group consisting of a single bond, an arylene group, and a heteroarylene group. HAr is an aromatic heterocyclic group having electron-accepting nitrogen.

R ^{41 to} R ⁴⁸ are each hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group, heteroaryl Selected from the group consisting of a group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a silyl group and —P (═O) R ⁵⁰ R ⁵¹ . R ⁵⁰ and R ⁵¹ are an aryl group or a heteroaryl group. R ^{41 to} R ⁴⁸ may form a ring with adjacent substituents. R ⁴⁹ is selected from the group consisting of an alkyl group, an aryl group, and a heteroaryl group. However, any one of R ^{41 to} R ⁴⁹ is connected to any position of R ^{31 to} R ³⁸ in the general formula (1).

  Of these substituents, hydrogen may be deuterium. The alkyl group represents, 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. It 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.

  An alkenyl group shows the unsaturated aliphatic hydrocarbon group containing double bonds, such as a vinyl group, an allyl group, and a butadienyl group, and this may or may not have a substituent. Although carbon number of an alkenyl group is not specifically limited, Usually, it is the range of 2-20.

  The cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond such as a cyclopentenyl group, a cyclopentadienyl group, or a cyclohexenyl group, which may have a substituent. You don't have to.

  An alkynyl group shows the unsaturated aliphatic hydrocarbon group containing triple bonds, such as an ethynyl group, for example, and may or may not have a substituent. Although carbon number of an alkynyl 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 fluorenyl 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 is a carbon such as a furanyl group, a thiophenyl group, a pyridyl group, a quinolinyl group, a pyrazinyl group, a naphthyridyl group, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, or a carbazolyl group. A cyclic aromatic group having one or more atoms in the ring, which may be unsubstituted or substituted. Although carbon number of heteroaryl group is not specifically limited, Usually, it is the range of 2-30.

  The halogen atom represents fluorine, chlorine, bromine or iodine. The carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, and phosphine oxide group may or may not have a substituent. Examples of the substituent include an alkyl group, a cycloalkyl group, and an aryl group. Group, heteroaryl group and the like, and these substituents may be further substituted.

  The carbonyl group, carboxyl group, oxycarbonyl group, and carbamoyl group may or may not have a substituent. Examples of the substituent include an alkyl group, a cycloalkyl group, and an aryl group. The substituent may be further substituted.

  The amino group may be unsubstituted or substituted, and examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, and the like, and these substituents may be further substituted. .

  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. The number of silicon is usually in the range of 1 to 6.

  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. The carbon number of the arylene group is not particularly limited, but is usually in the range of 6 or more and 40 or less. When L in the general formula (1) is an arylene group, the arylene group may or may not have a substituent, but the number of carbons including the substituent is in the range of 6 to 60. .

  A heteroarylene group is a furanyl group, thiophenyl group, pyridyl group, quinolinyl group, isoquinolinyl group, pyrazinyl group, pyrimidyl group, naphthyridyl group, benzofuranyl group, benzothiophenyl group, indolyl group, dibenzofuranyl group, dibenzothiophenyl group And a divalent group derived from a cyclic aromatic group having one or more atoms other than carbon in the ring, such as a carbazolyl 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 L in the general formula (1) is a heteroarylene group, the heteroarylene group may or may not have a substituent, but the number of carbons including the substituent is 2 or more and 50 or less. It is a range.

When adjacent substituents form a ring, any adjacent two substituents (for example, R ² and R ^{3 in} formula (3)) 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.

  An aromatic heterocyclic group containing electron-accepting nitrogen is a pyridyl group, a quinolinyl group, an isoquinolinyl group, a quinoxanyl group, a pyrazinyl group, a pyrimidyl group, a pyridazinyl group, a phenanthrolinyl group, an imidazopyridyl group, a triazyl group, an acridyl group Of the above heteroaryl groups, such as benzoimidazolyl, benzoxazolyl, and benzothiazolyl, a cyclic aromatic group having at least one electron-accepting nitrogen atom in the ring as an atom other than carbon.

  The aromatic heterocyclic group containing electron-accepting nitrogen may be unsubstituted or substituted. The number of electron-accepting nitrogen contained in the aromatic heterocyclic group containing electron-accepting nitrogen is not particularly limited, but is usually in the range of 1 or more and 3 or less. Moreover, there is no restriction | limiting in particular in the substituent in case the aromatic heterocyclic group containing electron-accepting nitrogen is substituted, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned. Among them, a substituent that does not significantly impair the electronic properties of the aromatic heterocyclic group containing electron-accepting nitrogen is preferable, for example, an aromatic hydrocarbon having 6 to 30 carbon atoms, an aromatic containing electron-accepting nitrogen having 5 to 20 carbon atoms. Group heterocyclic groups are mentioned as preferred substituents. Specifically, for example, phenyl, naphthyl, biphenyl, fluorenyl, phenanthryl, terphenyl, pyrenyl, pyridyl, quinolinyl, isoquinolinyl, quinoxanyl, pyrazinyl, pyrimidyl, pyridazinyl, Examples thereof include, but are not limited to, nantrolinyl group, imidazopyridyl group, triazyl group, acridyl group, benzoimidazolyl group, benzoxazolyl group, and benzothiazolyl group.

  The electron-accepting nitrogen mentioned here represents a nitrogen atom forming a multiple bond with an adjacent atom. Since the nitrogen atom has high electronegativity, the multiple bond has an electron accepting property. Therefore, an aromatic heterocycle containing electron-accepting nitrogen has a high electron affinity.

  Although carbon number of the aromatic heterocyclic group containing electron-accepting nitrogen is not specifically limited, Usually, it is the range of 2-30. The connecting position of the aromatic heterocyclic group containing electron-accepting nitrogen may be any part. For example, in the case of a pyridyl group, it may be any of 2-pyridyl group, 3-pyridyl group and 4-pyridyl group.

  Conventional compounds having a carbazole skeleton do not necessarily have sufficient performance as a light emitting device material. In studying the improvement, the present inventors paid attention to the strength of hole transport ability and electron transport ability of a compound having a carbazole skeleton. In general, a compound having a carbazole skeleton has a property of transporting both charges of holes and electrons. However, since the present inventors have poor electron transport ability with respect to hole transport ability, Based on this hypothesis, the inventors have invented a compound having a carbazole skeleton represented by the general formula (1).

  The compound having a carbazole skeleton represented by the general formula (1) has an aromatic heterocycle containing a carbazole skeleton and electron-accepting nitrogen in the molecule. As a result, the aromatic heterocycle containing electron-accepting nitrogen participates in the injection and transport of electrons, so that the electron transport ability is increased, the charge in the light-emitting layer is balanced, and high-efficiency light emission and excellent durability are achieved. It is thought to develop. In addition, by connecting the carbazole skeleton, a high triplet level of the carbazole skeleton itself can be maintained, and easy deactivation can be suppressed, so that high light emission efficiency is achieved.

  Among the compounds represented by the general formula (1) of the present invention, a compound having a carbazole skeleton represented by the general formula (3) is preferable.

R ^{1 to} R ¹⁴ are each hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group, heteroaryl Selected from the group consisting of a group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a silyl group and —P (═O) R ¹⁶ R ¹⁷ . R ¹⁶ and R ¹⁷ are an aryl group or a heteroaryl group. R ^{1 to} R ¹⁴ may form a ring with adjacent substituents. R ¹⁵ is selected from the group consisting of an alkyl group, an aryl group, and a heteroaryl group. L is selected from the group consisting of a single bond, an arylene group, and a heteroarylene group. HAr is an aromatic heterocyclic group having electron-accepting nitrogen.

  The explanation of these substituents is the same as that of the general formula (1).

Further, when R ⁴⁹ and L-HAr in the compound represented by the general formula (1) and R ¹⁵ and L-HAr in the compound represented by the general formula (3) are different groups, the molecule has an asymmetric structure. This is preferable because the effect of suppressing the interaction between carbazole skeletons is increased, a stable thin film can be formed, and the durability is improved.

R ¹⁵ and R ⁴⁹ are preferably a substituent that does not lower the triplet level of the compound having a carbazole skeleton, and among them, a substituent that does not greatly extend conjugation is preferable. In particular, a methyl group, a phenyl group, a biphenyl group, a terphenyl group, a pyridyl group, a pyrimidyl group, and a triazyl group are preferable.

  HAr is preferably a substituent that does not lower the triplet level of the compound having a carbazole skeleton represented by general formula (1) or general formula (3), and among them, a substituent that does not greatly extend conjugation is preferable. Particularly preferred are a pyridyl group, a pyrimidyl group and a triazyl group.

  A known method can be used for the synthesis of the compound having a carbazole skeleton represented by the general formula (1). Examples of the method for synthesizing the carbazole dimer include a method using an oxidative coupling reaction of carbazole under iron (III) chloride, but are not limited thereto. Examples of a method for introducing a substituent onto N of carbazole include a method using a coupling reaction between a carbazole derivative and a halide using a palladium or copper catalyst, but is not limited thereto. .

  Although it does not specifically limit as a carbazole compound represented by the said General formula (1), The following examples are specifically mentioned.

  The compound having a carbazole skeleton represented by the general formula (1) in the present invention is used as a light emitting device material. Here, the light emitting device material in the present invention represents a material used for any layer of the light emitting device, and is a material used for a hole transport layer, a light emitting layer and / or an electron transport layer as described later. In addition, the material used for the protective film of a cathode is also included. By using the compound having the carbazole skeleton represented by the general formula (1) in the present invention in any layer of the light emitting element, a light emitting element having high luminous efficiency and excellent durability can be obtained.

  The compound having a carbazole skeleton represented by the general formula (1) has high emission efficiency, high triplet level, bipolar property (both charge transport properties), and thin film stability. It is preferable to use it for a layer. In particular, since it has a high triplet level, it is preferably used for a light-emitting layer as a host material for a phosphorescent dopant.

  Next, embodiments of the light emitting device of the present invention will be described in detail. The light-emitting element of the present invention has an anode and a cathode, and an organic layer interposed between the anode and the cathode. The organic layer includes at least a light-emitting layer, and the light-emitting layer emits light by electric energy.

  The organic layer is composed of only the 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, etc. A configuration is mentioned. 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. The material is included in the hole transport material, and the electron injection material is included in the electron transport material.

  In the light emitting device of the present invention, the anode and the cathode have a role for supplying a sufficient current for light emission of the device, and at least one of them is preferably transparent or translucent in order to extract light. Usually, the anode formed on the substrate is a transparent electrode.

  The material used for the anode is a material that can efficiently inject holes into the organic layer, and is transparent or translucent to extract light. Tin oxide, indium oxide, indium tin oxide (ITO) indium zinc oxide (IZO) Although not particularly limited, such as conductive metal oxides such as, 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 It is particularly desirable to use ITO glass or Nesa glass. These electrode materials may be used alone, or a plurality of materials may be laminated or mixed. The resistance of the transparent electrode is not limited as long as a current sufficient for light emission of the element can be supplied, but it is desirable that the resistance be low from the viewpoint of power consumption of the element. For example, an ITO substrate with a resistance of 300Ω / □ or less will function as a device electrode, but since it is now possible to supply a substrate with a resistance of approximately 10Ω / □, use a substrate with a low resistance of 20Ω / □ 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. As for the glass material, alkali-free glass is preferred because it is better that there are fewer ions eluted from the glass. Alternatively, soda lime glass provided with a barrier coat such as SiO ₂ is also commercially available and can be used. Furthermore, if the first electrode functions stably, the substrate need not be glass, and for example, an 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 is not particularly limited as long as it can efficiently inject electrons into the light emitting layer. Generally, metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, or alloys and multilayer stacks of these metals with low work function metals such as lithium, sodium, potassium, calcium, and magnesium Is preferred. Among these, aluminum, silver, and magnesium are preferable as the main component from the viewpoints of electrical resistance, ease of film formation, film stability, luminous efficiency, and the like. In particular, magnesium and silver are preferable because electron injection into the electron transport layer and the electron injection layer in the present invention is facilitated and low voltage driving is possible.

  Furthermore, for cathode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, inorganic materials such as silica, titania and silicon nitride, polyvinyl alcohol, polyvinyl chloride As a preferred example, an organic polymer compound such as a hydrocarbon polymer compound is laminated on the cathode as a protective film layer. However, in the case of an element structure (top emission structure) that extracts light from the cathode side, the protective film layer is selected from materials that are light transmissive in the visible light region. The production method of these electrodes is not particularly limited, such as resistance heating, electron beam, sputtering, ion plating and coating.

  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 needs to efficiently transport holes from the positive electrode between electrodes to which an electric field is applied, and has a high hole injection efficiency, and it is desirable to transport the injected holes efficiently. For this purpose, it is required that the material has an appropriate ionization potential, has a high hole mobility, is excellent in stability, and does not easily generate trapping impurities during manufacture and use. Although it does not specifically limit as a substance which satisfy | fills such conditions, 4,4'-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl, 4,4'-bis (N-- Triphenylamine derivatives such as (1-naphthyl) -N-phenylamino) biphenyl, 4,4 ′, 4 ″ -tris (3-methylphenyl (phenyl) amino) triphenylamine, bis (N-allylcarbazole) or Biscarbazole derivatives such as bis (N-alkylcarbazole), pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives and thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives and other heterocyclic compounds, fullerene derivatives, polymers In the system, the polycarbonate having the monomer in the side chain Chromatography with or styrene derivatives, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole and polysilane are preferred.

  Furthermore, inorganic compounds such as p-type Si and p-type SiC can also be used. Further, a compound represented by the following general formula (4), tetrafluorotetracyanoquinodimethane (4F-TCNQ), or molybdenum oxide can also be used.

R ^{18 to} R ²³ may be the same or different and are selected from the group consisting of a halogen, a sulfonyl group, a carbonyl group, a nitro group, a cyano group, and a trifluoromethyl group.

  Among these, it is preferable that the compound (5) (1,4,5,8,9,12-hexaazatriphenylenehexacarbonitrile) is contained in the hole transport layer or the hole injection layer because it can be driven at a lower voltage.

  In the present invention, the light emitting layer may be either a single layer or a plurality of layers, each formed of a light emitting material (host material, dopant material), which may be a mixture of a host material and a dopant material or a host material alone. It may be either. That is, in the light emitting element of the present invention, only the host material or the dopant material may emit light in each light emitting layer, or both the host material and the dopant material may emit light. From the viewpoint of efficiently using electric energy and obtaining light emission with high color purity, the light emitting layer is preferably composed of a mixture of a host material and a dopant material. Further, the host material and the dopant material may be either one kind or a plurality of combinations, respectively. The dopant material may be included in the entire host material or may be partially included. The dopant material may be laminated or dispersed. The dopant material can control the emission color. 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 simultaneously deposited after being previously mixed with the host material.

  The compound having a carbazole skeleton represented by the general formula (1) may be used as an electron transporting material because it has an aromatic heterocyclic group having electron-accepting nitrogen, but as a light-emitting material because it has high light-emitting performance. Preferably used. Moreover, since the light emitting element material of the present invention exhibits strong light emission in a blue-green to red region (500 to 680 nm region), it can be suitably used as a blue-green to red light-emitting material. In addition, when used as a host-dopant-based light emitting material, the compound having a carbazole skeleton represented by the general formula (1) may be used as a dopant material, but is suitable as a host material because it has excellent thin film stability. Used for. When a compound having a carbazole skeleton represented by the general formula (1) is used as a host material, green light emission or red light emission with high emission efficiency and high color purity can be obtained according to the type of dopant used in combination.

  In addition to the compound having the carbazole skeleton represented by the general formula (1), the luminescent material includes a condensed ring derivative such as anthracene and pyrene, tris (8-quinolinolato) aluminum, which has been known as a luminescent material. Metal chelated oxinoid compounds, bisstyryl derivatives such as bisstyrylanthracene derivatives and distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadi Azole derivatives, thiadiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, in polymer systems, polyphenylene vinylene derivatives, polyparaphenylene derivatives, and Such as Li thiophene derivatives can be used but are not particularly limited.

  The host material contained in the light emitting material need not be limited to only one type of compound having the carbazole skeleton represented by the general formula (1), and a mixture of compounds having a plurality of carbazole skeletons of the present invention may be used. One or more kinds of the host material may be mixed with the compound having a carbazole skeleton of the present invention. Although it does not specifically limit as a host material which can be mixed, The compound which has condensed aryl rings, such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, indene, its derivative, N, N ' Metal chelated oxinoid compounds including aromatic amine derivatives such as dinaphthyl-N, N′-diphenyl-4,4′-diphenyl-1,1′-diamine, tris (8-quinolinato) aluminum (III), Bisstyryl derivatives such as distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, pyrrolopyrrole derivatives, thiadia In the case of lopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, and polymer systems, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinyl carbazole derivatives, polythiophene derivatives, etc. can be used but are particularly limited is not. Among them, as a host used when the light emitting layer emits phosphorescence, a metal chelated oxinoid compound, a dibenzofuran derivative, a carbazole derivative, an indolocarbazole derivative, a triazine derivative, or the like is preferably used.

  The triplet light emitting material used as the dopant material is at least selected from the group consisting of iridium (Ir), ruthenium (Ru), palladium (Pd), platinum (Pt), osmium (Os), and rhenium (Re). A metal complex compound containing one metal is preferable. The ligand preferably has a nitrogen-containing aromatic heterocycle such as a phenylpyridine skeleton or a phenylquinoline skeleton. However, it is not limited to these, and an appropriate complex is selected from the relationship with the required emission color, device performance, and host compound. Specifically, tris (2-phenylpyridyl) iridium complex, tris {2- (2-thiophenyl) pyridyl} iridium complex, tris {2- (2-benzothiophenyl) pyridyl} iridium complex, tris (2-phenyl) Benzothiazole) iridium complex, tris (2-phenylbenzoxazole) iridium complex, trisbenzoquinoline iridium complex, bis (2-phenylpyridyl) (acetylacetonato) iridium complex, bis {2- (2-thiophenyl) pyridyl} iridium Complex, bis {2- (2-benzothiophenyl) pyridyl} (acetylacetonato) iridium complex, bis (2-phenylbenzothiazole) (acetylacetonato) iridium complex, bis (2-phenylbenzoxazole) (acetylacetate) ) Iridium complex, bisbenzoquinoline (acetylacetonato) iridium complex, bis {2- (2,4-difluorophenyl) pyridyl} (acetylacetonato) iridium complex, tetraethylporphyrin platinum complex, {tris (cenoyltrifluoro) Acetone) mono (1,10-phenanthroline)} europium complex, {tris (cenoyltrifluoroacetone) mono (4,7-diphenyl-1,10-phenanthroline)} europium complex, {tris (1,3-diphenyl-1) , 3-propanedione) mono (1,10-phenanthroline)} europium complex, trisacetylacetone terbium complex, and the like. Moreover, the phosphorescence dopant described in Unexamined-Japanese-Patent No. 2009-130141 is also used suitably. Although not limited thereto, an iridium complex or a platinum complex is preferably used because high-efficiency light emission is easily obtained.

  The compound having the carbazole skeleton represented by the general formula (1) used as the host material and the triplet light-emitting material used as the dopant material may each contain only one type or two types of the triplet light-emitting material. You may mix and use the above. When two or more triplet light emitting materials are used, the total weight of the dopant material is preferably 20% by weight or less with respect to the host material.

  In addition to the host material and the triplet light emitting material, the light emitting layer may further include a third component for adjusting the carrier balance in the light emitting layer or stabilizing the layer structure of the light emitting layer. . However, as the third component, a material that does not cause an interaction between the host material composed of the compound having the carbazole skeleton and the dopant material composed of the triplet light emitting material is selected.

  Preferable host and dopant in the triplet light emitting system are not particularly limited, but specific examples include the following.

  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. For this reason, the electron transport layer is required to be a substance 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. In particular, in the case of stacking a thick film, a compound having a molecular weight of 400 or more that maintains a stable film quality is preferable because a low molecular weight compound is likely to be crystallized to deteriorate the film quality. 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.

  As the electron transport material used for the electron transport layer, in addition to the compound having a carbazole skeleton represented by the general formula (1), condensed polycyclic aromatic derivatives such as naphthalene and anthracene, 4,4′-bis (diphenyl) Ethenyl) styryl aromatic ring derivatives typified by biphenyl, quinone derivatives such as anthraquinone and diphenoquinone, phosphorus oxide derivatives, quinolinol complexes such as tris (8-quinolinolato) aluminum (III), benzoquinolinol complexes, hydroxyazole complexes, azomethines Various metal complexes such as complexes, tropolone metal complexes, and flavonol metal complexes can be mentioned, but they are selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus because the driving voltage is reduced and high-efficiency light emission is obtained. Heteroa that consists of elements and contains electron-accepting nitrogen Compounds having Lumpur ring structure (hereinafter, referred to as "specific heteroaryl compound") is preferably used.

  A heteroaryl ring containing electron-accepting nitrogen has high electron affinity, excellent electron transporting ability, and can be used for an electron transporting layer to reduce the driving voltage of a light-emitting element. 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.

  Among these, a specific heteroaryl compound having a pyrene skeleton, a specific heteroaryl compound having an anthracene skeleton, and a specific heteroaryl compound having a phenanthroline skeleton are preferable.

  Although it does not specifically limit as a preferable electron transport material, The following examples are specifically mentioned. The following structure is an example, and similar compounds thereof, for example, pyrene derivatives substituted at the 1,3-position with an alkyl group, an aryl group or a heteroaryl group, and the 1,3,7-positions are an alkyl group, an aryl group Or a pyrene derivative substituted with a heteroaryl group, a pyrene derivative substituted with an alkyl group, an aryl group or a heteroaryl group at positions 1 and 6, and a 1,10 position substituted with an alkyl group, an aryl group or a heteroaryl group Anthracene derivatives and the like are also preferred examples.

  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 with 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 layer 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, etc., but resistance heating vapor deposition or electron beam vapor deposition is usually used in terms of element characteristics. preferable.

  The thickness of the organic layer is not limited because it depends on the resistance value of the luminescent material, but is preferably 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 electric energy, but a pulse current or an alternating current can also be used. The current value and 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 above.

Synthesis example 1
Synthesis of Compound [59] A mixed solution of 32.0 g of carbazole, 93.13 g of anhydrous iron chloride [III] and 400 ml of chloroform was stirred at room temperature for 22 hours under a nitrogen stream. This mixed solution was put into 1000 ml of methanol and stirred for 1 hour, followed by filtration. To the obtained powder, 600 ml of tetrahydrofuran was added and refluxed for 30 minutes, followed by filtration to remove insoluble substances. After evaporation, the product was dissolved in 100 ml of DMI with heating and recrystallized at 5 ° C. to obtain 14.0 g of 9H, 9′H-3,3′-bicarbazole.

  Next, a mixed solution of 14.0 g of 9H, 9′H-3,3′-bicarbazole, 8.59 g of iodobenzene, 400 ml of nitrobenzene, 5.72 g of copper powder and 12.44 g of potassium carbonate was added at 180 ° C. under a nitrogen stream. And stirred for 4 hours. After cooling to room temperature, nitrobenzene was removed by distillation under reduced pressure, and the residue was purified by silica gel chromatography and dried in vacuo to obtain 5.59 g of 9-phenyl-9H, 9′H-3,3′-bicarbazole. .

  Next, a mixed solution of 12.5 g of cyanuric chloride and 12.5 g of tetrahydrofuran was cooled to 0 ° C. and stirred under a nitrogen stream. To this mixed solution, 105.6 g of phenylmagnesium bromide (32% in THF) was slowly added dropwise over 1 hour and a half. At that time, the system temperature was maintained at 15 ° C. or lower. After dropping, the mixture was stirred at room temperature for 1.5 hours, and 80 ml of toluene was added and cooled to 0 ° C. To this mixed solution, 12% HCl was slowly added dropwise over 15 minutes. At that time, the system temperature was maintained at 30 ° C. or lower. Then, water was poured and extracted with toluene. The organic layer was washed twice with water, dried over magnesium sulfate and evaporated. The resulting concentrate was purified by silica gel column chromatography and vacuum-dried to obtain 8.15 g of 2-chloro-4,6-diphenyl-1,3,5-triazine.

  Next, a mixed solution of 0.40 g of 55% sodium hydride and 30 ml of dehydrated DMF was stirred at room temperature under a nitrogen stream. A solution prepared by dissolving 5.59 g of 9-phenyl-9H, 9'H-3,3'-bicarbazole in 100 ml of dehydrated DMF was slowly added dropwise to the mixed solution, and the mixture was stirred for 1 hour. Thereafter, 3.52 g of 2-chloro-4,6-diphenyl-1,3,5-triazine was dissolved in 130 ml of dehydrated DMF, slowly added dropwise, and further stirred for 3 and a half hours. After stirring, it was filtered. The obtained solid was heated and washed with 150 ml of methanol and then filtered. The obtained solid was purified by silica gel column chromatography, then recrystallized twice with a mixed solvent of tetrahydrafuran and methanol, and vacuum-dried to obtain 4.28 g of white powder.

The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the white crystals obtained above were the compound [59].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.32-7.36 (m, 1H), 7.45-7.55 (m, 5H), 7.63-7.69 (m, 11H), 7.83-7.85 (m, 1H), 7.99-8.01 (m, 1H), 8.20-8.21 (t, 1H), 8.25-8.53 ( m, 1H), 8.40-8.41 (d, 1H), 8.53-8.54 (d, 1H), 8.79-8.81 (m, 4H), 9.21-9. 23 (d, 1H), 9.26-9.27 (d, 1H).

This compound [59] was used as a light emitting device material after sublimation purification at about 320 ° 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 99.8% before sublimation purification and 99.9% after sublimation purification.

Synthesis example 2
Synthesis of Compound [44] 2,4,6-Trichloropyrimidine 10 g, phenylboronic acid 13.3 g, 2M aqueous sodium carbonate solution 163.5 ml, 1,2-dimethoxyethane 545 ml and bis (triphenylphosphine) palladium (II) dichloride The mixed solution was refluxed for 2 hours under a nitrogen stream. After cooling to room temperature, extraction with toluene was performed. The organic layer was washed twice with water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography and vacuum-dried to obtain 6.46 g of 2-chloro-4,6-diphenylpyrimidine.

  Next, 9-phenyl-9H, 9'H-3,3'-bicarbazole 4.08 g, 2-chloro-4,6-diphenylpyrimidine 2.93 g, sodium-t-butoxide 1.35 g, dehydrated o- A mixed solution of 100 ml of xylene was stirred at room temperature under a nitrogen stream. To this mixed solution were added 0.27 g of tris (dibenzylideneacetone) dipalladium (0) and 0.16 g of tri-tert-butylphosphonium tetrafluoroborate, and the mixture was stirred with heating at 140 ° C. for 1 hour. The mixed solution was filtered as it was and then evaporated. 200 ml of methanol was added and refluxed for 2 hours, followed by filtration. The obtained solid was purified by silica gel column chromatography and vacuum dried to obtain 5.7 g of pale yellow powder.

The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the pale yellow crystal obtained above was compound [44].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.32-7.35 (m, 1H), 7.42-7.67 (m, 16H), 7.83-7.85 (m, 1H), 7.93-7.95 (m, 1H), 8.00 (s, 1H), 8.22-8.23 (d, 1H), 8.25-8.27 (m, 1H) , 8.34-8.35 (m, 4H), 8.42-8.43 (d, 1H), 8.52-8.53 (d, 1H), 9.05-9.07 (d, 1H), 9.10-9.11 (d, 1H).

This compound [44] was used as a light emitting device material after sublimation purification at about 330 ° 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 99.8% before sublimation purification and 99.9% after sublimation purification.

Synthesis example 3
Synthesis of Compound [18] 4.0 g of 2,4,6-trichloropyridine, 5.3 g of phenylboronic acid, 87 ml of 1M aqueous sodium carbonate solution, 108 ml of 1,2-dimethoxyethane and bis (triphenylphosphine) palladium (II) dichloride 290 mg of the mixed solution was refluxed for 3 hours under a nitrogen stream. After cooling to room temperature, extraction with toluene was performed. The organic layer was washed twice with water, dried over magnesium sulfate and evaporated. The resulting concentrate was purified by silica gel column chromatography and vacuum-dried to obtain 2.7 g of 4-chloro-2,6-diphenylpyridine.

  Next, 3.0 g of 9-phenyl-9H, 9′H-3,3′-bicarbazole, 2.15 g of 4-chloro-2,6-diphenylpyridine, 0.99 g of sodium t-butoxide, dehydrated o- A mixed solution of 73 ml of xylene was stirred at room temperature under a nitrogen stream. To this mixed solution were added 0.13 g of tris (dibenzylideneacetone) dipalladium (0) and 58 mg of tri-tert-butylphosphonium tetrafluoroborate, and the mixture was heated and stirred at 140 ° C. for 6 hours. The mixed solution was filtered as it was and then evaporated. 100 ml of methanol was added and refluxed for 2 hours, then cooled to room temperature and filtered. The obtained solid was purified by silica gel column chromatography and vacuum dried to obtain 2.9 g of pale yellow powder.

The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the pale yellow powder obtained above was compound [18].
¹ H-NMR (DMSO-d6 (d = ppm)): 7.32-7.36 (m, 1H), 7.40-7.60 (m, 12H), 7.68-7.77 (m , 5H), 7.83-7.84 (d, 1H), 7.91-7.93 (m, 1H), 7.95-7.97 (m, 1H), 8.29 (s, 2H) ), 8.34-8.37 (m, 4H), 8.40-8.41 (d, 1H), 8.44-8.46 (d, 1H), 8.73-8.75 (m , 2H).

This compound [18] was used as a light emitting device material after sublimation purification at about 320 ° 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 99.8% before sublimation purification and 99.9% after sublimation purification.

Synthesis example 4
Synthesis of Compound [38] 9-phenyl-9H, 9′H-3,3′-bicarbazole 3.03 g, 1.84 g of 1-bromo-3,5-dichlorobenzene, 1.0 g of sodium t-butoxide, A mixed solution of 70 ml of dehydrated o-xylene was stirred at room temperature under a nitrogen stream. To this mixed solution were added 85 mg of tris (dibenzylideneacetone) dipalladium (0) and 86 mg of tri-tert-butylphosphonium tetrafluoroborate, and then the mixture was heated and stirred at 140 ° C. for 4 hours. The mixed solution was filtered as it was and then evaporated. The obtained solid was purified by silica gel column chromatography and vacuum-dried, and then 3.29 g of 9- (3,5-dichlorophenyl) -9′-phenyl-9H, 9′H-3,3′-bicarbazole was obtained. Obtained.

  Next, 9- (3,5-dichlorophenyl) -9'-phenyl-9H, 9'H-3,3'-bicarbazole 3.29 g, 3-pyridineboronic acid 1.5 g, 1.27 M triphosphate A mixed solution of 21 ml of an aqueous potassium solution, 30 ml of 1,4-dioxane, 136 mg of tris (dibenzylideneacetone) dipalladium (0) and 79 mg of tricyclohexylphosphine was refluxed for 12 hours under a nitrogen stream. After cooling to room temperature, extraction with toluene was performed. The organic layer was washed twice with water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography and vacuum-dried to obtain 2.4 g of a pale yellow powder.

The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the pale yellow powder obtained above was compound [38].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.31-7.38 (m, 2H), 7.43-7.57 (m, 8H), 7.61-7.66 (m, 5H), 7.77-7.83 (m, 2H), 7.88-7.91 (m, 3H), 8.01-8.04 (m, 2H), 8.23-8.28 ( m, 2H), 8.47-8.49 (m, 2H), 8.69-8.70 (m, 2H), 9.01-9.02 (d, 2H).

This compound [38] was used as a light emitting device material after sublimation purification at about 320 ° 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 99.8% before sublimation purification and 99.9% after sublimation purification.

Synthesis example 5
Synthesis of Compound [224] 3,6-dibromocarbazole 5.0 g, phenylcarbazole-3-boronic acid 2.96 g, palladium acetate 267 mg, tris (2-methylphenyl) phosphine 234 mg, 1M aqueous potassium carbonate solution 30 ml, dimethoxyethane 80 ml The mixed solution was refluxed for 2 hours under a nitrogen stream. After cooling to room temperature, extraction was performed with 100 ml of toluene. The organic layer was washed twice with 50 ml of water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography and vacuum-dried to obtain 3.48 g of 6-bromo-9′-phenyl-9H, 9′H-3,3′-bicarbazole.

  Next, 6.48 g of 6-bromo-9′-phenyl-9H, 9′H-3,3′-bicarbazole, 1.32 g of 3-pyridineboronic acid, 100 mg of bis (triphenylphosphine) palladium (II) dichloride A mixed solution of 1M sodium carbonate aqueous solution (14 ml) and 1,4-dioxane (35 ml) was refluxed for 2 hours under a nitrogen stream. After cooling to room temperature, extraction was performed with 50 ml of toluene. The organic layer was washed 3 times with 20 ml of water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography, dried in vacuo, and then 2.1 g of 9'-phenyl-6- (pyridin-3-yl) -9H, 9'H-3,3'-bicarbazole. Got.

  Next, a mixed solution of 231 mg of 55% sodium hydride and 10 ml of dehydrated DMF was stirred at room temperature under a nitrogen stream. To this mixed solution was slowly added dropwise a solution prepared by dissolving 2.1 g of 9'-phenyl-6- (pyridin-3-yl) -9H, 9'H-3,3'-bicarbazole in 15 ml of dehydrated DMF for 3 hours. Stir. Thereafter, 1.20 g of 2-chloro-4,6-diphenyl-1,3,5-triazine was dissolved in 25 ml of dehydrated DMF, slowly added dropwise, and further stirred for 2 and a half hours. After stirring, it was filtered. The obtained solid was refluxed with 50 ml of methanol for 1 hour, cooled to room temperature, and filtered. The obtained solid was purified by silica gel column chromatography, recrystallized with DMF, and vacuum-dried to obtain 2.11 g of white powder.

The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the white crystals obtained above were the compound [224].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.31-7.34 (m, 1H), 7.39-7.41 (m, 1H), 7.44-7.45 (m, 2H), 7.49-7.52 (m, 2H), 7.60-7.67 (m, 10H), 7.79-7.81 (m, 2H), 7.94-7.96 ( m, 1H), 8.02-8.04 (m, 1H), 8.23-8.25 (d, 1H), 8.300-8.303 (d, 1H), 8.370-8. 373 (d, 1H), 8.495-8.498 (d, 1H), 8.62-8.63 (t, 1H), 8.72-8.75 (m, 4H), 9.040- 9.043 (d, 1H), 9.18-9.23 (m, 2H).

This compound [224] was used as a light emitting device material after sublimation purification at about 360 ° 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 99.7% before sublimation purification and 99.8% after sublimation purification.

Example 1
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited to 125 nm was cut into 38 × 46 mm and etched. The obtained substrate was ultrasonically cleaned with “Semico Clean 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, copper phthalocyanine was vapor-deposited to a thickness of 10 nm and 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl was vapor-deposited as a hole injection material by a resistance heating method.

Next, Compound [59] as a host material and D-1 as a dopant material were vapor-deposited to a thickness of 40 nm so that the doping concentration was 10 wt% as a light emitting material. Next, as an electron transport material, E-1 shown below was laminated to a thickness of 20 nm. Next, after depositing lithium fluoride in a thickness of 0.5 nm, aluminum was deposited in a thickness of 70 nm to form a cathode, thereby fabricating a 5 × 5 mm square device. The film thickness referred to here is a crystal oscillation type film thickness monitor display value. When this light emitting device was DC-driven at 10 mA / cm ² , high efficiency green light emission with a light emission efficiency of 20.0 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 2000 hours.

Comparative Example 1
A light emitting device was fabricated in the same manner as in Example 1 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 , green light emission with a luminous efficiency of 10.4 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 400 hours.

Comparative Example 2
A light-emitting element was fabricated in the same manner as in Example 1 except that H-2 shown by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , green light emission with a light emission efficiency of 19.1 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 300 hours.

Comparative Example 3
A light emitting device was fabricated in the same manner as in Example 1 except that H-3 represented by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , green light emission with a luminous efficiency of 12.3 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 700 hours.

Comparative Example 4
A light emitting device was produced in the same manner as in Example 1 except that H-4 represented by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , green light emission with a luminous efficiency of 11.0 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 700 hours.

Comparative Example 5
A light emitting device was produced in the same manner as in Example 1 except that H-5 represented by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , green light emission with a luminous efficiency of 9.0 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 700 hours.

Example 2
A light emitting device was produced in the same manner as in Example 1 except that the compound [44] was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , high efficiency green light emission with a light emission efficiency of 21.0 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 2200 hours.

Example 3
A light emitting device was produced in the same manner as in Example 1 except that the compound [62] was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , high efficiency green light emission with a light emission efficiency of 19.2 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 1500 hours.

Example 4
A light emitting device was produced in the same manner as in Example 1 except that the compound [18] was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , high efficiency green light emission with a light emission efficiency of 19.0 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 1300 hours.

Example 5
A light emitting device was produced in the same manner as in Example 1 except that the compound [38] was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , high efficiency green light emission with a light emission efficiency of 19.0 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 1300 hours.

Example 6
A light emitting device was produced in the same manner as in Example 1 except that the compound [224] was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , high efficiency green light emission with a light emission efficiency of 23.0 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 1800 hours.

  The results of Examples 1 to 6 and Comparative Examples 1 to 5 are shown in Table 1.

Examples 7-8 , Reference Examples 9-10, Examples 11-13
A light emitting device was produced in the same manner as in Example 1 except that the materials described in Table 2 were used as the host material, the dopant material, and the electron transport material. The results are shown in Table 2. In Table 2, E-2 is a compound shown below.

Comparative Example 6
A light emitting device was produced in the same manner as in Example 1 except that the materials described in Table 2 were used as the host material, the dopant material, and the electron transport material. The results are shown in Table 2.

Examples 14-18
A light emitting device was fabricated in the same manner as in Example 1 except that the materials described in Table 3 were used as the host material, the dopant material, and the electron transport material. The results are shown in Table 3. In Table 3, E-3, E-4, E-5, E-6, and E-7 are the compounds shown below.

Example 19
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam evaporated product) on which an ITO transparent conductive film is deposited to 125 nm is cut into 30 × 40 mm, and a 300 μm pitch (remaining width 270 μm) × 32 pieces is obtained by photolithography. Patterned into 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 cleaned with acetone and “Semicocrine 56” (trade name, 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, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl was deposited as a hole transport material by a resistance heating method to a thickness of 150 nm. Next, the compound [59] as a host material and (D-1) as a dopant material were vapor-deposited to a thickness of 40 nm so that the doping concentration was 10%. Next, E-1 was laminated to a thickness of 20 nm as an electron transport material. The film thickness referred to here is a crystal oscillation type film thickness monitor display value. 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 with a mask so as to be orthogonal to the ITO stripe in vacuum, It fixed with the magnet from the back surface so that a mask and an ITO board | substrate might closely_contact | adhere. Then, after 0.5 nm of lithium fluoride was deposited, 200 nm of aluminum was deposited to prepare a 32 × 16 dot matrix element. When this element was driven in matrix, characters could be displayed without crosstalk.

  The light emitting device material of the present invention can be used for a light emitting device and the like, and can provide a light emitting device material useful as a light emitting dye. According to the present invention, a light emitting device having both high luminous efficiency and excellent durability can be obtained. The light-emitting element of the present invention can be used in the fields of display elements, flat panel displays, backlights, illumination, interiors, signs, signboards, electrophotographic machines, optical signal generators, and the like.

Claims (14)

One or more layers including at least a light emitting layer exist between an anode and a cathode, and emit light by electric energy, the light emitting layer being a triplet light emitting material and a carbazole skeleton represented by the following general formula (3) emitting element characterized by containing a compound having a.

(R ^{1 to} R ¹⁴ are each hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, aryl group, hetero group, Selected from the group consisting of an aryl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, carbamoyl group, amino group, silyl group, and -P (= O) R ¹⁶ R ^17. R ¹⁶ and R ¹⁷ are an aryl group or R ^{1 to} R ¹⁴ may form a ring with adjacent substituents R ¹⁵ is selected from the group consisting of an alkyl group, an aryl group and a heteroaryl group, L is a single bond, Selected from the group consisting of an arylene group and a heteroarylene group, HAr represents an electron-accepting nitrogen; A pyridyl group, quinolinyl group, isoquinolinyl group, pyrazinyl group, pyrimidyl group, pyridazinyl group, phenanthrolinyl group, imidazopyridyl group, triazyl group, acridyl group, benzoimidazolyl group, benzoxazolyl group Selected from the group consisting of a group and a benzothiazolyl group.) L-HAr emitting element according to claim 1, wherein the R ¹⁵ are different groups. The electron or accepting nitrogen aromatic heterocyclic group having a is an unsubstituted, emission element according to claim 1 or 2, wherein substituted with an alkyl group or aryl group. An electron transport layer further exists between the anode and the cathode, and the electron transport layer is composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus, and includes a heteroaryl ring containing electron-accepting nitrogen. The light emitting element in any one of Claims 1-3 containing the compound which has a structure. The compound used for the electron transport layer is a compound composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus, and having a heteroaryl ring structure containing an electron-accepting nitrogen and a pyrene skeleton. Item 5. A light emitting device according to Item 4 . The compound used for the electron transport layer is composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus, and has a heteroaryl ring structure containing an electron-accepting nitrogen and a pyrene skeleton. Pyrene derivatives substituted with alkyl group, aryl group or heteroaryl group at positions 1, 3; Pyrene derivatives substituted with alkyl group, aryl group or heteroaryl group at positions 1, 3, 7; The light emitting device according to claim 5 , wherein the light emitting device is any one of a pyrene derivative substituted with an alkyl group, an aryl group or a heteroaryl group. The light emitting device according to claim 5 or 6, wherein the compound used for the electron transport layer is one of the following compounds.

The light emitting device according to claim 4 , wherein the compound used for the electron transport layer is a phenanthroline derivative composed of an element selected from hydrogen, nitrogen, oxygen, silicon, and phosphorus. The light emitting device according to claim 8 , wherein the compound used for the electron transport layer is the following compound.

The compound used for the electron transport layer is a compound composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus, and having a heteroaryl ring structure containing an electron-accepting nitrogen and an anthracene skeleton. The light-emitting device according to claim 4, which is an anthracene derivative substituted at the 1,10-position with an alkyl group, an aryl group or a heteroaryl group. The light emitting device according to claim 10, wherein the compound used for the electron transport layer is any of the following compounds.

The light emitting device according to claim 4 , wherein the compound used for the electron transport layer is an oligopyridine derivative composed of an element selected from hydrogen, nitrogen, oxygen, silicon, and phosphorus. The light emitting device according to claim 4 , wherein the compound used for the electron transport layer is the following compound.

The electron transport layer further exists between the anode and the cathode, and the compound having a carbazole skeleton represented by the general formula (3) is further included in the electron transport layer . The light emitting element of description.