JPWO2014007022A1 - Light emitting device material and light emitting device - Google Patents

Abstract

By using a light emitting device material containing a compound having a specific carbazole skeleton, an organic thin film light emitting device having both high luminous efficiency and durability can be provided.

Description

  The present invention relates to a light emitting element capable of converting electric energy into light and a light emitting element material used therefor. More specifically, the present invention relates to a light-emitting element that can be used in the fields of display elements, flat panel displays, backlights, lighting, interiors, signs, signboards, electrophotographic machines, optical signal generators, and light-emitting element materials used therefor. .

  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 phosphor 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 fluorescent material.

  This study was conducted by C.D. W. Since Tang et al. Showed that organic thin film devices emit light with high brightness, many practical studies have been made, and organic thin film light emitting devices have been steadily put into practical use, such as being used in mobile phone main displays. Is progressing. However, there are still many technical issues. Above all, it is one of the major issues to achieve both high efficiency and long life of the device.

  The driving voltage of the element greatly depends on a carrier transport material that transports carriers such as holes and electrons to the light emitting layer. Among these, materials having a carbazole skeleton are known as materials that transport holes (hole transport materials) (see, for example, Patent Documents 1 and 2). Moreover, it is known that the material having the carbazole skeleton has a high triplet level (see, for example, Patent Document 3), and is particularly used as a material for confining triplet excitons from a phosphorescent light emitting layer. It has been proposed (see, for example, Patent Document 4).

JP-A-8-3547 Korean Patent Application Publication No. 2010-0079458 International Publication No. 2011/024451 International Publication No. 2012/001986

  However, it is difficult for the conventional technology to sufficiently reduce the drive voltage of the element, and even if the drive voltage can be reduced, the light emission efficiency and durability life of the element are insufficient. Thus, no technology has yet been found to achieve both high luminous efficiency and durable life.

  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 has improved luminous efficiency and durability.

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

R ^{1 to} R ¹⁶ may be the same as or different from each other, and may be hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, It is selected from the group consisting of a carbamoyl group, a silyl group, and —P (═O) R ¹⁷ R ¹⁸ . R ¹⁷ and R ¹⁸ are an aryl group or a heteroaryl group. However, two carbazole skeletons are linked at any position of R ^{1 to} R ⁸ and any position of R ^{9 to} R ¹⁶ . Ar ¹ and Ar ³ may be the same or different and each represents a substituted or unsubstituted phenyl group. Ar ² represents a substituted or unsubstituted phenylene group. Ar ⁴ is a group represented by the following formula (A) or (B).

R ^{19 to} R ³⁶ may be the same or different and each represents hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, It is selected from the group consisting of a carbamoyl group, a silyl group, and —P (═O) R ³⁷ R ³⁸ . R ³⁷ and R ³⁸ are an aryl group or a heteroaryl group. However, in Formula (A), it connects with a nitrogen atom in any one position among R < ¹⁹ > -R < ²⁸ >, and in Formula (B) in any one position among R < ²⁹ > -R < ³⁶ >. X is an oxygen atom, a sulfur atom, or N—Ar ⁵ . Ar ⁵ represents a substituted or unsubstituted phenyl group. Y represents a carbon atom, and n is 0 or 1. When n is 1, Y may be substituted with an alkyl group.

  According to the present invention, it is possible to provide an organic electroluminescence device having high luminous efficiency and further having a sufficient durability life.

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

R ^{1 to} R ¹⁶ may be the same as or different from each other, and may be hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, It is selected from the group consisting of a carbamoyl group, a silyl group, and —P (═O) R ¹⁷ R ¹⁸ . R ¹⁷ and R ¹⁸ are an aryl group or a heteroaryl group. However, two carbazole skeletons are linked at any position of R ^{1 to} R ⁸ and any position of R ^{9 to} R ¹⁶ . Ar ¹ and Ar ³ may be the same or different and each represents a substituted or unsubstituted phenyl group. Ar ² represents a substituted or unsubstituted phenylene group. Ar ⁴ is a group represented by the following formula (A) or (B).

R ^{19 to} R ³⁶ may be the same or different and each represents hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, It is selected from the group consisting of a carbamoyl group, a silyl group, and —P (═O) R ³⁷ R ³⁸ . R ³⁷ and R ³⁸ are an aryl group or a heteroaryl group. However, in Formula (A), it connects with a nitrogen atom in any one position among R < ¹⁹ > -R < ²⁸ >, and in Formula (B) in any one position among R < ²⁹ > -R < ³⁶ >. X is an oxygen atom, a sulfur atom, or N—Ar ⁵ . Ar ⁵ represents a substituted or unsubstituted phenyl group. Y represents a carbon atom, and n is 0 or 1. When n is 1, Y may be substituted with an alkyl group.

  Of these substituents, hydrogen may be deuterium. Further, hydrogen in an unsubstituted phenyl group or the like may be deuterium.

  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, which is a substituent. It may or may not have. 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 in terms 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. Although carbon number of a cycloalkenyl group is not specifically limited, Usually, it is the range of 2-20.

  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.

  Halogen is fluorine, chlorine, bromine or iodine.

  The carbonyl group, carboxyl group, oxycarbonyl group, and carbamoyl group may or may not have a substituent.

  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.

—P (═O) R ¹⁷ R ¹⁸ may or may not have a substituent.

  The aryl group represents an aromatic hydrocarbon group such as a phenyl group, a biphenyl group, a fluorenyl group, a phenanthryl group, a triphenylenyl group, or a terphenyl 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 ring having one or more atoms other than carbon such as furanyl group, thiophenyl group, pyridyl group, pyrazinyl group, pyrimidinyl group, triazinyl group, benzofuranyl group, benzothiophenyl group, indolyl group in the ring. Represents an aromatic group, which may be unsubstituted or substituted. Although carbon number of heteroaryl group is not specifically limited, Usually, it is the range of 2-30.

  An arylene group refers to a divalent group derived from an aryl group, and examples thereof include a phenylene group, a naphthylene group, a biphenylene group, a fluorenylene group, a phenanthrylene group, a terphenylene group, an anthracenylene group, and a pyrenylene group. These may or may not have a substituent. 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. Moreover, when an arylene group has a substituent, it is preferable that carbon number is 6 or more and 60 or less including a substituent.

When two carbazole skeletons are linked at any position of R ^{1 to} R ⁸ and any position of R ^{9 to} R ¹⁶ , for example, the case where they are linked at the position of R ^{6 and} the position of R ¹⁰ is exemplified. , R ⁶ is directly bonded to the carbon atom of the portion to which R ¹⁰ is bonded. Similarly, the coupling with the nitrogen atom in the one position one of R ¹⁹ to R ²⁸ are, for example, include the case of connecting the nitrogen atom at the position of R ²¹ as an example, the portion where R ²¹ is bonded It means that a carbon atom and a nitrogen atom are directly bonded.

  Conventional compounds having a carbazole skeleton do not necessarily have sufficient performance as a light emitting device material. For example, 9,9'-diphenyl-9H, 9'H-3,3'-bicarbazole and 1,3-di (9H-carbazol-9-yl) benzene (abbreviation: mCP) have high triplet levels. Although it is a general-purpose material as an exciton block material, there is a problem that the ionization potential is large, the hole injection / transport property is poor, and the driving voltage is increased. There is also a problem that the glass transition temperature which affects the durability of the device is low.

  In the study of the improvement, the present inventors paid attention to the strength of the hole transport ability and the high triplet energy of the compound having a carbazole skeleton. In general, a compound having a carbazole skeleton has a property of transporting both charges of holes and electrons. The present inventors have a conventional compound having a carbazole skeleton, since the hole transport ability thereof is small, the proportion of holes entering the light emitting layer is smaller than electrons entering from the electron transport layer, and the charge in the light emitting layer is reduced. I thought that the loss of the balance might lead to a decrease in device performance.

  Therefore, when carbazole is dimerized like the compound of the present invention, conjugation expands and hole transportability is improved. However, when there is a substituent on the nitrogen atom, depending on the type, there is a concern that the hole transport ability may be inhibited, and not all carbazole dimers have high hole transportability.

  Here, when the substituent on the nitrogen atom of the carbazole dimer has an amine skeleton that exhibits excellent properties as a hole-transporting substituent, it can have higher hole-transporting properties. Become. However, even in this case, the triplet energy may be lowered depending on the substituent in the amine skeleton.

  For example, a naphthyl group such as that of Compound 33 or Compound 36 (structure shown below) in Korean Patent Application Publication No. 2010-0079458 has a low triplet level in itself and lowers the triplet level of the compound. I found out. When a compound having a low triplet level is used as an exciton blocking material and a light emitting element is formed, the light emission efficiency is lowered by excitons leaking from the light emitting layer.

  On the other hand, a compound having a substituent at the ortho position of the carbazole dimer, such as the compound shown in Table 1 of International Publication No. 2006/61759, has a twisted molecule. Therefore, even when carbazole is dimerized, conjugation does not expand, the triplet level of carbazole itself can be maintained, and the triplet level as a compound also shows a high value. However, as described above, since the conjugation is not expanded, the effect of improving the hole transportability cannot be obtained.

  As described above, maintaining a high triplet level and exhibiting high hole transportability are in a trade-off relationship, and no material that can be compatible at the stage of practical use has been found. As a result of intensive studies, the present inventors have found that a compound having a group represented by the formula (A) or (B) as a substituent on the amine skeleton has a high triplet level as the amine skeleton on the nitrogen atom. The present inventors have found that it has a high hole transport property while maintaining it, and have reached the present invention.

  The compound represented by the general formula (1) preferably contains two or three carbazole skeletons in the molecule, thereby having high thin film stability and excellent heat resistance.

In addition, the compound represented by the general formula (1) exhibits an excellent hole transport ability when the substituent on one nitrogen atom in the carbazole skeleton has an amine skeleton. Furthermore, in the compound in which Ar ⁴ is a group represented by the formula (A) or (B), the conjugated system is difficult to spread more than necessary. Therefore, since the molecular weight can be increased without lowering the triplet energy, the glass transition temperature is increased. Further, since a stable thin film can be formed, the durability of the element is improved.

Furthermore, X of the group represented by the formula (A) or (B) is bonded to the para-position relative to the nitrogen atom to be substituted, that is, in the formula (A), at the position of R ²¹ , the formula (A) in B) in the position for R ^31, a is preferably connected to the nitrogen atom. This is because the ionization potential can be further reduced and the hole injection capability can be further increased.

In the general formula (1), Ar ¹ and Ar ³ are substituted or unsubstituted phenyl groups, and Ar ² is a substituted or unsubstituted phenylene group. In this case, the substituent is preferably an alkyl group or halogen. Alkyl groups and halogens hardly affect conjugation and can maintain a high triplet level.

  The carbazole dimer skeleton of the compound represented by the general formula (1) preferably has a nitrogen atom in the para position as in the form represented by the general formula (2). This is because this structure has the same site as the benzidine skeleton, so that the ionization potential is further reduced, and the hole injecting ability and hole transporting ability are further improved.

R ^{39 to} R ⁵² may be the same as or different from each other, and may be hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group, It is selected from the group consisting of a carbamoyl group, a silyl group, and —P (═O) R ⁵³ R ⁵⁴ . R ⁵³ and R ⁵⁴ are an aryl group or a heteroaryl group. Ar ⁶ and Ar ⁸ may be the same or different and each represents a substituted or unsubstituted phenyl group. Ar ⁷ represents a substituted or unsubstituted phenylene group. Ar ⁹ is a group represented by the formula (A) or (B).

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

  When the hole transport layer is in direct contact with the light emitting layer containing the triplet light emitting dopant, the triplet energy of the compound represented by the general formula (1) or the general formula (2) is 2.70 eV or more. Preferably there is. This is because leakage of triplet excitation energy from the light emitting layer can be suppressed at a high level, and the light emission efficiency of the light emitting element can be further increased and the lifetime can be extended.

  The triplet energy in the present invention is a value obtained by converting the wavelength at the rising position of the short wavelength of the phosphorescence spectrum into light energy.

Furthermore, Ar ^{1 of} the compound represented by the general formula (1) and Ar ⁶ of the compound represented by the general formula (2) are preferably unsubstituted phenyl groups. This is because a high triplet level can be maintained for a longer period of time, and easy deactivation can be suppressed, so that higher luminous efficiency is achieved. For the same reason, Ar ^{2 of} the compound represented by the general formula (1) and Ar ⁷ of the compound represented by the general formula (2) are preferably unsubstituted phenylene groups. Ar ³ and Ar ⁵ of the represented compound are preferably unsubstituted phenyl groups. Further, n in the formula (B) is preferably 0. This is because the thermal stability at the time of vapor deposition of the compound represented by the general formula (1) is further improved.

R ^{1 to} R ⁵⁴ are most preferably all hydrogen, considering the availability of raw materials and the synthesis cost. When R ^{1 to} R ⁵⁴ are groups other than hydrogen, an alkyl group, a cycloalkyl group, or an alkoxy group is preferable as a group that does not lower the triplet level and has little effect of increasing the ionization potential. These groups may be further substituted.

  Although it does not specifically limit as a compound represented by the said General formula (1), Specifically, the following examples are given. In addition, the following is an illustration, and even if it is other than the compound specified here, if it is represented by General formula (1), it is preferably used similarly.

  A known method can be used for the synthesis of the compound having a carbazole skeleton as described above. Examples of the method for synthesizing the carbazole dimer include a method using a coupling reaction between a carbazole derivative using a palladium or copper catalyst and a halide or triflate, but is not limited thereto. . As an example, an example using 9-phenylcarbazole-3-boronic acid is shown below.

  In the above reaction, the reaction proceeds similarly even when 9-phenylcarbazole-2-boronic acid ester is used instead of 9-phenylcarbazole-3-boronic acid. In this case, a positional isomer of a carbazole dimer can be synthesized.

  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. . As an example, an example using N- (4-chlorophenyl) -N, 9-diphenyl-9H-carbazolyl-3-amine is shown below.

  The compound represented by the general formula (1) 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 as described later, in the hole injection layer, the hole transport layer, the light emitting layer and / or the electron transport layer. In addition to the materials used, the materials used for the cathode protective film are also included. By using the compound 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.

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

  In such a light emitting device, the layer structure between the anode and the cathode is composed of only the light emitting layer, 1) light emitting layer / electron transport layer, 2) hole transport layer / light emitting layer, and 3) hole transport. Layer / light emitting layer / electron transport layer, 4) hole injection layer / hole transport layer / light emitting layer / electron transport layer, 5) hole transport layer / light emitting layer / electron transport layer / electron injection layer, 6) hole A laminated structure such as injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer can be mentioned. Each of the layers may be either a single layer or a plurality of layers, and may be doped.

  The compound represented by the general formula (1) may be used in any of the above layers in the light emitting device, but is particularly preferably used in the hole transport layer.

  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.

  If 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, zinc oxide, tin oxide, indium oxide, indium tin oxide (ITO), zinc oxide In particular, conductive metal oxides such as indium (IZO), metals such as gold, silver and chromium, inorganic conductive materials such as copper iodide and copper sulfide, and conductive polymers such as polythiophene, polypyrrole and polyaniline are particularly limited. Although not intended, 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 45 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 injection layer is a layer inserted between the anode and the hole transport layer. The hole injection layer may be either a single layer or a plurality of layers stacked. The presence of a hole injection layer between the hole transport layer and the anode is preferable because it not only drives at a lower voltage and improves the durability life, but also improves the carrier balance of the device and the light emission efficiency.

  The material used for the hole injection layer is not particularly limited. For example, 4,4′-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl (TPD), 4,4′-bis (N -(1-naphthyl) -N-phenylamino) biphenyl (NPD), 4,4'-bis (N, N-bis (4-biphenylyl) amino) biphenyl (TBDB), bis (N, N'-diphenyl- Benzidine derivatives such as 4-aminophenyl) -N, N-diphenyl-4,4′-diamino-1,1′-biphenyl (TPD232), 4,4 ′, 4 ″ -tris (3-methylphenyl (phenyl) amino ) Starvers such as triphenylamine (m-MTDATA), 4,4 ′, 4 ″ -tris (1-naphthyl (phenyl) amino) triphenylamine (1-TNATA) Material group called triarylamine, biscarbazole derivatives such as bis (N-arylcarbazole) or bis (N-alkylcarbazole), pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives , Phthalocyanine derivatives, heterocyclic compounds such as porphyrin derivatives, and polymer systems such as polycarbonates and styrene derivatives, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, and polysilane having the above monomers in the side chain are used. Moreover, the compound represented by General formula (1) can also be used. Among them, there are more benzidine derivatives and starburst arylamine group materials from the viewpoint of having a shallower HOMO level than the compound represented by the general formula (1) and smoothly injecting and transporting holes from the anode to the hole transport layer. Preferably used.

  These materials may be used alone or as a mixture of two or more materials. A plurality of materials may be stacked to form a hole injection layer. Further, it is more preferable that the hole injection layer is composed of an acceptor compound alone or that the hole injection material is doped with an acceptor compound so that the above-described effects can be obtained more remarkably. . An acceptor compound is a material that forms a charge transfer complex with a material that forms a hole-injecting layer in contact with a hole-transporting layer when used as a single-layer film and a material that forms a hole-injecting layer when used as a doped layer. When such a material is used, the conductivity of the hole injection layer is improved, which contributes to lowering of the driving voltage of the device, and the effects of improving the light emission efficiency and improving the durability life can be obtained.

  Examples of acceptor compounds include metal chlorides such as iron (III) chloride, aluminum chloride, gallium chloride, indium chloride, antimony chloride, metal oxides such as molybdenum oxide, vanadium oxide, tungsten oxide, ruthenium oxide, A charge transfer complex such as tris (4-bromophenyl) aminium hexachloroantimonate (TBPAH). In addition, organic compounds having a nitro group, cyano group, halogen or trifluoromethyl group in the molecule, quinone compounds, acid anhydride compounds, fullerenes, and the like are also preferably used. Specific examples of these compounds include hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane (TCNQ), tetrafluorotetracyanoquinodimethane (F4-TCNQ), a radiane derivative, p-fluoranyl, p-chloranil, p-bromilyl, p-benzoquinone, 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone, tetramethylbenzoquinone, 1,2,4,5-tetracyanobenzene, o-dicyanobenzene, p-dicyano Benzene, 1,4-dicyanotetrafluorobenzene, 2,3-dichloro-5,6-dicyanobenzoquinone, p-dinitrobenzene, m-dinitrobenzene, o-dinitrobenzene, p-cyanonitrobenzene, m-cyanonitrobenzene, o − Anonitrobenzene, 1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1-nitronaphthalene, 2-nitronaphthalene, 1,3-dinitronaphthalene, 1,5-dinitronaphthalene, 9-cyanoanthracene, 9-nitroanthracene, 9,10-anthraquinone, 1,3,6,8-tetranitrocarbazole, 2,4,7-trinitro-9-fluorenone, 2,3,5,6-tetracyanopyridine, maleic anhydride, phthalic anhydride Product, C60, and C70.

  Among these, metal oxides and cyano group-containing compounds are preferable because they are easy to handle and easy to deposit, so that the above-described effects can be easily obtained. In any case where the hole injection layer is composed of an acceptor compound alone or when the hole injection layer is doped with an acceptor compound, the hole injection layer may be a single layer, A plurality of layers may be laminated.

  The hole transport layer is a layer that transports holes injected from the anode to the light emitting layer. The hole transport layer may be a single layer or may be configured by laminating a plurality of layers.

  The compound represented by the general formula (1) has an ionization potential of 5.1 to 6.0 eV (measured value of deposited film AC-2 (RIKEN meter)), a high triplet energy level, a high hole transport property and Since it has thin film stability, it is preferably used for the hole injection layer and the hole transport layer of the light-emitting element. In addition, the compound represented by the general formula (1) has a large energy gap with respect to a conventional hole transport material having a benzidine skeleton, and thus has a high LUMO level and an excellent electron blocking property. Furthermore, the compound represented by the general formula (1) is preferably used as a hole transport material of an element using a triplet light emitting material. A conventional hole transport material having a benzidine skeleton has a low triplet level, and if it is in direct contact with a light-emitting layer containing a triplet light-emitting material, leakage of triplet energy occurs and the light emission efficiency decreases. This is because the compound represented by the formula (1) has a high triplet energy and does not cause such a problem.

  In the case of being composed of a plurality of hole transport layers, the hole transport layer containing the compound represented by the general formula (1) is preferably in direct contact with the light emitting layer. This is because the compound represented by the general formula (1) has a high electron blocking property and can prevent intrusion of electrons flowing out from the light emitting layer. Furthermore, since the compound represented by the general formula (1) has a high triplet level, it also has an effect of confining the excitation energy of the triplet light-emitting material. Therefore, even when a triplet light emitting material is included in the light emitting layer, the hole transport layer containing the compound represented by the general formula (1) is preferably in direct contact with the light emitting layer.

  The hole transport layer may be composed only of the compound represented by the general formula (1), or may be mixed with other materials as long as the effects of the present invention are not impaired. In this case, examples of other materials used include 4,4′-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl (TPD), 4,4′-bis (N- (1 -Naphtyl) -N-phenylamino) biphenyl (NPD), 4,4'-bis (N, N-bis (4-biphenylyl) amino) biphenyl (TBDB), bis (N, N'-diphenyl-4-amino) Benzidine derivatives such as phenyl) -N, N-diphenyl-4,4′-diamino-1,1′-biphenyl (TPD232), 4,4 ′, 4 ″ -tris (3-methylphenyl (phenyl) amino) triphenyl Starburst aryl such as amine (m-MTDATA), 4,4 ′, 4 ″ -tris (1-naphthyl (phenyl) amino) triphenylamine (1-TNATA) A group of materials called min, biscarbazole derivatives such as bis (N-arylcarbazole) or bis (N-alkylcarbazole), pyrazoline derivatives, stilbene compounds, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, phthalocyanines Derivatives, heterocyclic compounds such as porphyrin derivatives, in the case of polymer systems, polycarbonates and styrene derivatives, polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, polysilane and the like having the above-mentioned monomer in the side chain are exemplified.

  The light emitting layer may be either a single layer or a plurality of layers, each formed by 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 a mixture of two types of host materials and one type of dopant material. 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. When the amount of the dopant material is too large, a concentration quenching phenomenon occurs, so that it is preferably used at 30% by weight or less, more preferably 20% by weight or less based on 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.

  In addition to the compound represented by the general formula (1), the luminescent material is a metal chelation such as a condensed ring derivative such as anthracene or pyrene, tris (8-quinolinolato) aluminum, which has been known as a luminescent material. 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, oxadiazole derivatives, thiols Asiazolopyridine derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, in polymer systems, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polythiophene derivatives, etc. Do not can be used particularly limited.

  The host material contained in the light-emitting material is not limited to a single compound, and a plurality of compounds of the present invention may be mixed and used, or one or more other host materials may be mixed and used. . Further, they may be used in a stacked manner. The host material is not particularly limited, but is a compound having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, indene, or a derivative thereof, N, N′-dinaphthyl- Aromatic amine derivatives such as N, N′-diphenyl-4,4′-diphenyl-1,1′-diamine, metal chelated oxinoid compounds such as tris (8-quinolinato) aluminum (III), distyrylbenzene Bisstyryl derivatives such as derivatives, tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, pyrrolopyrrole derivatives, thiadiazolopyridines In derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, polymer systems, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinyl carbazole derivatives, polythiophene derivatives, etc. can be used but are not particularly limited. Absent. Among them, as a host used when the light emitting layer performs triplet light emission (phosphorescence light emission), metal chelated oxinoid compounds, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, triphenylene derivatives, etc. Are 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, dopants used when the light emitting layer emits triplet light emission (phosphorescence emission) include iridium (Ir), ruthenium (Ru), palladium (Pd), platinum (Pt), osmium (Os), and rhenium. A metal complex compound containing at least one metal selected from the group consisting of (Re) is preferable. The ligand preferably has a nitrogen-containing aromatic heterocycle such as a phenylpyridine skeleton, a phenylquinoline skeleton, or a carbene 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.

  As for the said triplet light emitting material used as a dopant material, only 1 type may be contained in the light emitting layer, respectively, and 2 or more types may be mixed and used for it. When two or more triplet light emitting materials are used, the total weight of the dopant material is preferably 30% by weight or less, more preferably 20% by weight or less, based on 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 represented by the general formula (1) 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.

  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 mentioned here represents a nitrogen atom forming a multiple bond with an adjacent atom. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron accepting property. Therefore, an aromatic heterocycle containing electron-accepting nitrogen has a high electron affinity. An electron transport material having electron-accepting nitrogen makes it easier to receive electrons from a cathode having a high electron affinity, and can be driven at a lower voltage. In addition, since the number of electrons supplied to the light emitting layer is increased and the recombination probability is increased, the light emission efficiency is improved.

  Examples of the heteroaryl ring containing an electron-accepting nitrogen include, for example, a pyridine ring, pyrazine ring, pyrimidine ring, quinoline ring, quinoxaline ring, naphthyridine ring, pyrimidopyrimidine ring, benzoquinoline ring, phenanthroline ring, imidazole ring, oxazole ring, Examples thereof include an oxadiazole 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. In addition, it is more preferable that these derivatives have a condensed polycyclic aromatic skeleton because the glass transition temperature is improved, the electron mobility is increased, and the effect of lowering the voltage of the light-emitting element is increased. Furthermore, considering that the device durability life is improved, the synthesis is easy, and the availability of raw materials is easy, the condensed polycyclic aromatic skeleton is particularly preferably an anthracene skeleton, a pyrene skeleton or a phenanthroline skeleton. 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. Absent.

  Although it does not specifically limit as a preferable electron transport material, The following examples are specifically mentioned.

  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. Absent. Moreover, you may contain a donor compound. Here, the donor compound is a compound that facilitates electron injection from the cathode or the electron injection layer to the electron transport layer by improving the electron injection barrier and further improves the electrical conductivity of the electron transport layer.

  Preferred examples of the donor compound include an alkali metal, an inorganic salt containing an alkali metal, a complex of an alkali metal and an organic substance, an alkaline earth metal, an inorganic salt containing an alkaline earth metal, or an alkaline earth metal and an organic substance. And the like. Preferred types of alkali metals and alkaline earth metals include alkaline metals such as lithium, sodium, potassium, rubidium, and cesium that have a large effect of improving the electron transport ability with a low work function, and alkaline earths such as magnesium, calcium, cerium, and barium. A metal is mentioned.

In addition, since it is easy to deposit in vacuum and is excellent in handling, it is preferably in the form of a complex with an inorganic salt or an organic substance rather than a single metal. Furthermore, it is more preferable that it is in the state of a complex with an organic substance in terms of facilitating handling in the air and easy control of the addition concentration. Examples of inorganic salts include oxides such as LiO and Li ₂ O, nitrides, fluorides such as LiF, NaF, and KF, Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Rb ₂ CO ₃ , Examples thereof include carbonates such as Cs ₂ CO ₃ . Further, preferred examples of the alkali metal or alkaline earth metal include lithium and cesium from the viewpoint that a large low-voltage driving effect can be obtained. In addition, preferable examples of the organic substance in the complex with the organic substance include quinolinol, benzoquinolinol, pyridylphenol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, and hydroxytriazole. Among them, a complex of an alkali metal and an organic substance is preferable from the viewpoint that the effect of lowering the voltage of the light emitting device is larger, and a complex of lithium and an organic substance is more preferable from the viewpoint of ease of synthesis and thermal stability, Particularly preferred is lithium quinolinol, which can be obtained at a low cost.

  The ionization potential of the electron transport layer is not particularly limited, but is preferably 5.6 eV or more and 8.0 eV or less, and more preferably 5.6 eV or more and 7.0 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.

Moreover, about the measurement of the lowest excitation triplet energy of each compound, the compound of this invention prepared 1.0x10 < ^-5 > mol / l 2-methyltetrahydrofuran solution. The prepared solution was put into a dedicated quartz tube, and nitrogen bubbling was performed to remove dissolved oxygen. Further, in order to prevent oxygen contamination, the cap was capped with a septum stopper. After cooling this sample to about 77K with liquid nitrogen, a phosphorescence spectrum was measured using a fluorescence phosphorescence spectrophotometer (manufactured by Horiba, Ltd., FluoroMax-4P). The triplet energy (T1) was calculated by reading the wavelength at the rising position of the short wavelength of the phosphorescence spectrum and converting the wavelength value into light energy.

Synthesis of Compound [1] 3-Bromocarbazole 20.9 g, 9-phenylcarbazole-3-boronic acid 15.0 g, palladium acetate 366 mg, tris (2-methylphenyl) phosphine 300 mg, 2M aqueous potassium carbonate solution 105 ml, dimethoxyethane 260 ml The mixed solution was refluxed for 6 hours under a nitrogen stream. After cooling to room temperature, extraction was performed with 500 ml of tetrahydrofuran. The organic layer was washed twice with 100 ml of saturated brine, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by o-xylene recrystallization and vacuum-dried to obtain 13.5 g of 9-phenyl-9H, 9′H-3,3′-bicarbazole.

Next, 4.32 g of aniline, 15.0 g of 4-bromotriphenylamine, 267 mg of bis (dibenzylideneacetone) palladium, 270 mg of trit-butylphosphine tetrafluoroborate, 6.25 g of sodium tert-butoxide and 232 ml of o-xylene The mixed solution was heated and stirred for 1 hour under reflux in a nitrogen stream. After cooling to room temperature, extraction was performed with 50 ml of toluene. The organic layer was washed 3 times with 30 ml of water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography, and the solid obtained by evaporation was vacuum-dried to obtain 9.33 g of N ¹ , N ¹ , N ⁴ -triphenylbenzene-1,4-diamine. It was.

^{Next, N 1, N 1, N} 4 - triphenyl-1,4-diamine 9.33 g, 1-bromo-4-chlorobenzene 5.83 g, palladium acetate 62 mg, tri t- butylphosphine tetrafluoroborate 161mg Then, a mixed solution of 3.72 g of sodium tert-butoxide and 134 ml of o-xylene was heated and stirred under reflux in a nitrogen stream for 1.5 hours. After cooling to room temperature, extraction was performed with 50 ml of toluene. The organic layer was washed 3 times with 30 ml of water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography, and the solid obtained by evaporation was vacuum-dried, and then N ^1- (4-chlorophenyl) -N ¹ , N ⁴ , N ⁴ -triphenylbenzene-1 , 4-72 g of 4-diamine was obtained.

^Next, N 1 - (4- ^{chlorophenyl) -N 1, N 4, N} 4 - triphenyl-1,4-diamine 5.72 g, 9-phenyl -9H, 9'H-3,3'- bi 4.75 g of carbazole, 67 mg of bis (dibenzylideneacetone) palladium, 82 mg of di-t-butyl (2,2-diphenyl-1-methyl-1-cyclopropyl) phosphine, 1.56 g of sodium tert-butoxide and 58 ml of o-xylene The mixed solution was heated and stirred for 2 hours under a nitrogen stream under reflux. After cooling to room temperature, extraction was performed with 50 ml of toluene. The organic layer was washed 3 times with 30 ml of water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography, and the solid obtained by evaporation was vacuum dried to obtain 4.0 g of compound [1].

The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the white solid obtained above was Compound [1].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.25-7.79 (t, 36H), 8.22-8.25 (m, 3H), 8.45 (s, 3H).

This compound [1] 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 99.8% before sublimation purification and 99.9% after sublimation purification.
Further, the lowest excited triplet energy level T1 of the compound [1] was 2.72 eV.

Synthesis example 2
Synthesis of Compound [13] 3-Bromocarbazole 20.9 g, 9-phenylcarbazole-3-boronic acid 15.0 g, palladium acetate 366 mg, tris (2-methylphenyl) phosphine 300 mg, 2M aqueous potassium carbonate solution 105 ml, dimethoxyethane 260 ml The mixed solution was refluxed for 6 hours under a nitrogen stream. After cooling to room temperature, extraction was performed with 500 ml of tetrahydrofuran. The organic layer was washed twice with 100 ml of saturated brine, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by o-xylene recrystallization and vacuum-dried to obtain 13.5 g of 9-phenyl-9H, 9′H-3,3′-bicarbazole.

  Next, a mixed solution of aniline 2.89 g, 3-bromophenylcarbazole 10.0 g, palladium acetate 139 mg, tri-t-butylphosphine tetrafluoroborate 360 mg, sodium tert-butoxide 4.18 mg, and o-xylene 155 ml was streamed with nitrogen The mixture was stirred under heating for 1 hour under reflux. After cooling to room temperature, extraction was performed with 50 ml of toluene. The organic layer was washed 3 times with 30 ml of water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography, and the solid obtained by evaporation was vacuum-dried to obtain 4.33 g of N, 9-diphenyl-9H-carbazol-3-amine.

  Next, 4.33 g of N, 9-diphenyl-9H-carbazol-3-amine, 2.73 g of 1-bromo-4-chlorobenzene, 29 mg of palladium acetate, 75 mg of tri-t-butylphosphine tetrafluoroborate, sodium tert-butoxide A mixed solution of 1.74 g and 65 ml of o-xylene was heated and stirred for 1 hour under reflux in a nitrogen stream. After cooling to room temperature, extraction was performed with 50 ml of toluene. The organic layer was washed 3 times with 30 ml of water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography, and the solid obtained by evaporation was vacuum-dried, and then N- (4-chlorophenyl) -N, 9-diphenyl-9H-carbazol-3-amine. 65 g was obtained.

  Next, 3.65 g of N- (4-chlorophenyl) -N, 9-diphenyl-9H-carbazol-3-amine, 3.05 g of 9-phenyl-9H, 9′H-3,3′-bicarbazole, bis (Dibenzylideneacetone) palladium 43 mg, di-t-butyl (2,2-diphenyl-1-methyl-1-cyclopropyl) phosphine 52 mg, sodium tert-butoxide 1.0 g and o-xylene 37 ml were mixed in a nitrogen stream. The mixture was stirred for 2 hours under reflux. After cooling to room temperature, extraction was performed with 50 ml of toluene. The organic layer was washed 3 times with 30 ml of water, dried over magnesium sulfate and evaporated. The obtained concentrate was purified by silica gel column chromatography, and the solid obtained by evaporation was vacuum dried to obtain 4.72 g of compound [13].

The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the white solid obtained above was Compound [13].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.28-7.66 (t, 32H), 7.75-7.80 (m, 2H), 8.06-8.09 (d, 2H, J = 7.56), 8.21-8.25 (m, 2H), 8.44-8.46 (m, 2H).

This compound [13] 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 99.8% before sublimation purification, and 99.9% after sublimation purification. Further, the lowest excited triplet energy level T1 of the compound [13] was 2.75 eV.

Example 1
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited to 50 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. Compound HI-1 was deposited as a hole injection layer by 10 nm by a resistance heating method. Next, 80 nm of compound HT-6 was vapor-deposited as a 1st positive hole transport layer. Next, 10 nm of compound [1] was vapor-deposited as a 2nd positive hole transport layer. Next, as a light-emitting layer, Compound H-1 was used as the host material, Compound D-1 was used as the dopant material, and the dopant material was deposited to a thickness of 30 nm so that the doping concentration of the dopant material was 10% by weight. Next, Compound E-1 was laminated to a thickness of 35 nm as an electron transport layer.

Next, after depositing 1 nm of lithium quinolinol, a co-deposited film of magnesium and silver was deposited at a deposition rate ratio of magnesium: silver = 10: 1 (= 0.5 nm / s: 0.05 nm / s) to 100 nm to form a cathode. Then, a 5 × 5 mm square element was produced. 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 46.0 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 3050 hours. Compounds HI-1, HT-6, H-1, D-1, and E-1 are the compounds shown below.

Examples 2-4, Comparative Examples 1-8
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 second hole transport layer. The results are shown in Table 2. HT-1 to HT-8 are the compounds shown below, and their lowest excited triplet energy levels (T1) are as shown in Table 1.

Examples 5-8
A light emitting device was fabricated in the same manner as in Example 1 except that a mixed host of Compound H-1 and Compound H-2 was used as the host material at a deposition rate ratio of 1: 1 instead of Compound H-1. The results are shown in Table 2. H-2 is a compound shown below.

Example 9
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited to 50 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 device fabrication, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. Compound HI-1 was deposited as a hole injection layer by 10 nm by a resistance heating method. Next, 50 nm of compound HT-6 was vapor-deposited as a 1st positive hole transport layer. Next, 40 nm of compound [1] was deposited as a second hole transport layer. Next, as a light emitting layer, the compound H-3 was used as the host material, the compound D-2 was used as the dopant material, and the dopant material was vapor-deposited to a thickness of 30 nm so that the doping concentration of the dopant material was 5% by weight. Next, Compound E-1 was laminated to a thickness of 35 nm as an electron transport layer.

Next, after depositing 0.5 nm of lithium fluoride, 1000 nm of aluminum was vapor-deposited to form a cathode, and a 5 × 5 mm square device was fabricated. 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 red light emission with a light emission efficiency of 13.0 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 3000 hours. Compounds H-3 and D-2 are the compounds shown below.

Examples 10-12
A light emitting device was produced and evaluated in the same manner as in Example 9 except that the materials described in Table 3 were used as the second hole transport layer. The results are shown in Table 3.

Comparative Examples 9-16
A light emitting device was produced and evaluated in the same manner as in Example 9 except that the compounds described in Table 3 were used as the second hole transport layer. The results are shown in Table 3.

Example 13
A glass substrate (manufactured by Geomat Co., Ltd., 11Ω / □, sputtered product) on which an ITO transparent conductive film was deposited to 50 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 device fabrication, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. Compound [1] was deposited as a hole injection layer by 10 nm by a resistance heating method. Next, 90 nm of compound HT-6 was vapor-deposited as a positive hole transport layer. Next, as a light emitting layer, the compound H-3 was used as the host material, the compound D-2 was used as the dopant material, and the dopant material was vapor-deposited to a thickness of 30 nm so that the doping concentration of the dopant material was 5% by weight. Next, Compound E-1 was laminated to a thickness of 35 nm as an electron transport layer.

Next, after depositing 0.5 nm of lithium fluoride, 1000 nm of aluminum was vapor-deposited to form a cathode, and a 5 × 5 mm square device was fabricated. 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 red light emission with a light emission efficiency of 13.0 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 2800 hours.

Examples 14-16
A light emitting device was prepared and evaluated in the same manner as in Example 13 except that the materials described in Table 4 were used as the hole injection layer. The results are shown in Table 4.

Comparative Example 17
A light emitting device was prepared and evaluated in the same manner as in Example 13 except that the materials described in Table 4 were used as the hole injection layer. The results are shown in Table 4.

Claims (5)

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

(R ^{1 to} R ¹⁶ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group. , A carbamoyl group, a silyl group, and —P (═O) R ¹⁷ R ^18, wherein R ¹⁷ and R ¹⁸ are an aryl group or a heteroaryl group, provided that any one of R ^{1 to} R ⁸ Two carbazole skeletons are linked at the position and any position of R ^{9 to} R ^16. Ar ¹ and Ar ³ may be the same or different and each represents a substituted or unsubstituted phenyl group, and Ar ² is substituted. Alternatively, it represents an unsubstituted phenylene group, and Ar ⁴ is a group represented by the following formula (A) or (B).

(R ¹⁹ to R ³⁶ may be the same or different and each is a hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group , A carbamoyl group, a silyl group, and —P (═O) R ³⁷ R ^38, wherein R ³⁷ and R ³⁸ are an aryl group or a heteroaryl group, provided that in formula (A), R ¹⁹ to In any one position of R ²⁸ , in formula (B), it is linked to a nitrogen atom at any one position of R ^{29 to} R ^36. X is an oxygen atom, a sulfur atom, or N—Ar ^5. Ar ⁵ represents a substituted or unsubstituted phenyl group, Y represents a carbon atom, and n is 0 or 1. When n is 1, Y is (It may be substituted with an alkyl group.) The light emitting device material according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

(R ^{39 to} R ⁵² may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, halogen, carbonyl group, carboxyl group, oxycarbonyl group. , A carbamoyl group, a silyl group, and —P (═O) R ⁵³ R ^54. R ⁵³ and R ⁵⁴ are an aryl group or a heteroaryl group, and Ar ⁶ and Ar ⁸ are the same or different, respectively. And represents a substituted or unsubstituted phenyl group, Ar ⁷ represents a substituted or unsubstituted phenylene group, and Ar ⁹ represents a group represented by the formula (A) or (B). An organic layer is present between the anode and the cathode, and the light emitting element emits light by electric energy, and the light emitting element material according to claim 1 or 2 is contained in any layer between the anode and the cathode. A light emitting device characterized. The light emitting device according to claim 3, wherein at least a hole transport layer is present in the organic layer, and the hole transport layer contains the light emitting device material according to claim 1. The light emitting device according to claim 3, wherein at least a hole injection layer is present in the organic layer, and the hole injection layer contains the light emitting device material according to claim 1.