JP6197265B2 - 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 6). 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 7). ~ 8).

JP 2003-133075 A JP 2008-135498 A International Publication WO2008 / 56746 Pamphlet International Publication WO2008 / 123189 Pamphlet International Publication WO2010 / 15306 Pamphlet International Publication WO2011 / 19156 Pamphlet JP 2004-217557 A International Publication WO20111 / 24451 Pamphlet

  However, the organic thin film light emitting element needs to satisfy the improvement of the light emission efficiency, the reduction 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 a light-emitting element material comprising a compound having a carbazole skeleton represented by the following general formula (1), wherein the compound contains only two carbazole skeletons in the molecule.

(R ^{1 to} R ⁸ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl It consists of a thioether group, an aryl group, a heteroaryl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a silyl group, —P (═O) R ⁹ R ¹⁰ and the following general formula (2). R ⁹ and R ¹⁰ are an aryl group or a heteroaryl group, and at least one of R ^{1 to} R ⁸ is a group represented by the following general formula (2), and is selected from the group (2) .Y connecting with any position of ^R 19 ^{to R 23} in) is a single bond or an arylene group .Z the following formula Is a group represented by 3).

(R ^{11 to} R ²³ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, an aryl group, a heteroaryl group, halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, ^{.R 24} of chosen from the group consisting of silyl group, and ^{-P (= O) R 24 R} 25 And R ²⁵ represents an aryl group or a heteroaryl group, and R ^{19 to} R ²³ may form a ring with adjacent substituents, provided that any one of R ^{19 to} R ²³ has the general formula ( connecting with any of the positions of ^R 1 to R ⁸ in 1). ^Further, R 11 ^{to R 23} in general formula ( ) Except when coupled with any position of R ¹ to R ⁸ in the condensed ring structure containing a nitrogen atom, a condensed ring structure containing an oxygen atom, not including the condensed ring structure and an amine structure containing a sulfur atom In addition, the position of R ³ or R ⁶ in the general formula (1) and the position of R ¹³ or R ¹⁶ in the general formula (2) are not linked.)

(X ^{1 to} X ³ represents CH or N, and at least one of X ^{1 to} X ³ is N. Ar ¹ and Ar ² may be the same or different, and are not a condensed ring structure. Or an unsubstituted aryl group or heteroaryl 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 ^{1 to} R ⁸ may be the same as or different from each other, and are 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 ⁹ R ¹⁰ and the following general formula (2) More selected. R ⁹ and R ¹⁰ are an aryl group or a heteroaryl group. However, at least one of R ^{1 to} R ⁸ is a group represented by the following general formula (2), and is linked to any position among R ^{11 to} R ²³ in the general formula (2). Y is a single bond or an arylene group. Z is a group represented by the following formula (3).

R ^{11 to} R ²³ may be the same as or different from each other, and hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether Selected from the group consisting of a group, an aryl group, a heteroaryl 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 ²⁴ R ²⁵ . R ²⁴ and R ²⁵ are an aryl group or a heteroaryl group. R ^{19 to} R ²³ may form a ring with adjacent substituents. However, any one of R ^{11 to} R ²³ is connected to any position of R ^{1 to} R ⁸ in the general formula (1). R ^{11 to} R ²³ are each a condensed ring structure containing a nitrogen atom, a condensed ring structure containing an oxygen atom, except when linked to any position among R ^{1 to} R ⁸ in the general formula (1), A condensed ring structure containing a sulfur atom and an amine structure are not included. The position of ^{R 13} or ^{R 16} will not be connected at the location and the general formula of ^{R 3} or ^{R 6} in the general formula (1) (2).

X ^{1 to} X ³ represent CH or N, and at least one of X ^{1 to} X ³ is N. Ar ¹ and Ar ² may be the same or different and each represents a substituted or unsubstituted aryl group or heteroaryl group that is not a condensed ring structure.

  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 furanyl, thiophenyl, pyridyl, quinolinyl, pyrazinyl, naphthyridyl, benzofuranyl, benzothiophenyl, indolyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, etc. 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. Among these, a furanyl group, a thiophenyl group, a pyridyl group, and a pyrazinyl group are preferable.

  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. .

When adjacent substituents form a ring, any adjacent two substituents (for example, R ¹⁷ and R ^{18 in} formula (1)) can be bonded to each other to form a conjugated or non-conjugated condensed ring. As a constituent element of the condensed ring, in addition to carbon, nitrogen, oxygen, sulfur, phosphorus and silicon atoms may be contained, or further condensed with another ring.

  A condensed ring structure including a nitrogen atom, a condensed ring structure including an oxygen atom, and a condensed ring structure including a sulfur atom are compounds in which two or more aromatic rings are condensed, and include one or more nitrogen atoms, oxygen atoms, and And / or containing a sulfur atom. Specifically, benzo-fused ring structures such as quinoline structure, indole structure, benzofuran structure, benzothiophene structure, carboline structure, carbazole structure, dibenzofuran structure, dibenzothiophene structure, phenoxazine structure, phenothiazine structure, acridine structure, etc. Examples thereof include a ring structure.

  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 a pyridine ring, a pyrimidine ring or a triazine ring, which is an aromatic heterocyclic ring containing a carbazole skeleton and an 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, since the carbazole skeleton has a high triplet level, the compound having the carbazole skeleton represented by the general formula (1) can also maintain a high triplet level and can suppress easy deactivation. Therefore, high luminous efficiency is achieved.

Z is preferably a group that does not lower the triplet level of the compound having a carbazole skeleton represented by the general formula (1), and among them, a group that does not greatly increase conjugation is preferable. In particular, when ^{one of} X ^{1 to} X ³ is a nitrogen atom (N), X ³ is preferably a nitrogen atom, and when two of X ^{1 to} X ³ are nitrogen atoms, X ¹ and X ² is preferably a nitrogen atom. Among these, a case where all of X ^{1 to} X ³ are nitrogen atoms is preferable because of high electron transport ability.

Ar ¹ and Ar ² are each preferably a substituted or unsubstituted phenyl group among the above. Preferable specific examples include a phenyl group, a deuterated phenyl group, a biphenyl group, a terphenyl group, a 1-naphthyl group, and a 2-naphthyl group. Of these, a phenyl group, a deuterated phenyl group, a biphenyl group, and a terphenyl group are more preferable.

  More preferably, Y is a single bond.

Among R ^{1 to} R ⁸ , those other than the group represented by the general formula (2) are each preferably hydrogen (including deuterium), an alkyl group, an aryl group, or a heteroaryl group, among the above. Especially, it is one of the especially preferable aspects that at least 1 is an alkyl group or an aryl group among R < ¹ > -R < ⁸ >.

In addition, among R ^{11 to} R ²³ , those other than the group used for linking with R ^{1 to} R ⁸ in the general formula (1) are respectively hydrogen (including deuterium), an alkyl group, and an aryl group. Or it is preferable that it is a heteroaryl group. Among them, at least one of R ¹¹ to R ²³ is an alkyl group or aryl group is one of particularly preferred embodiments.

R ^{11 to} R ²³ are a condensed ring structure containing a nitrogen atom, a condensed ring structure containing an oxygen atom, or a sulfur atom, except when linked to any position among R ^{1 to} R ⁸ in the general formula (1). It does not contain a condensed ring structure or amine structure. This is because thermal decomposition may occur when such a structure is included.

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

The compound in which the position of R ³ or R ⁶ in general formula (1) and the position of R ¹³ or R ¹⁶ in general formula (2) are linked is a compound having a carbazole skeleton represented by general formula (1) of the present invention Is not included. This is due to the following reason. When the position of R ³ or R ⁶ in general formula (1) and the position of R ¹³ or R ¹⁶ in general formula (2) are linked, the distribution of HOMO (highest occupied orbit) is delocalized on the two carbazoles Therefore, the hole transport ability is increased. For this reason, even if a high electron transporting substituent such as a group represented by Z is introduced, the compound still has a high hole transporting property, and the balance of charges in the light emitting layer cannot be sufficiently improved. Since the compound represented by the general formula (1) of the present invention excludes the case where the position of R ³ or R ^{6 and} the position of R ¹³ or R ¹⁶ in the general formula (2) are linked, HOMO is localized in one of the carbazoles, and the hole transport ability decreases. When a high electron transporting substituent such as a group represented by Z is introduced in this state, the balance between the hole transporting ability and the electron transporting ability is maintained.

In the compound having a carbazole skeleton represented by the general formula (1), the group represented by the general formula (2) is R ¹¹ , R ¹² , R ¹⁴ , R ¹⁵ , R ¹⁷ , R ¹⁸ , R ¹⁹ , R ^20. , R ²¹ , R ²² , R ²³ are preferably used for linking with R ^{1 to} R ^8, and the group represented by the general formula (2) is any one of R ¹³ , R ¹⁶ It is preferably used for linking with R ¹ , R ² , R ⁴ , R ⁵ , R ⁷ , R ⁸ . In addition, for example, R ²¹ being used for connection with R ⁶ means that the R ⁶ portion of the general formula (1) and the R ²¹ portion of the general formula (2) are directly bonded. If the position of the position and ^{R 14} or ^{R 15} in ^{R 4} or ^{R 5} is linked is preferably subjected eliminated.

Among these, R ¹¹ , R ¹² , R ¹⁴ , R ¹⁵ , R ¹⁷ , R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ , wherein R ³ , R ⁶ is a group represented by the general formula (2) A compound linked to any one of R ²² and R ²³ is preferable because of excellent balance between hole transport ability and electron transport ability.

In addition, among the compounds represented by the general formula (1) of the present invention, any ^one of R ^{1 to} R ⁸ in the general formula (1) and any of R ^{19 to} R ²³ in the general formula (2) A compound in which such a position is linked is also preferred.

When any position among R ^{1 to} R ⁸ in the general formula (1) and any position among R ^{19 to} R ²³ in the general formula (2) is used for the connection, in the general formula (2) HOMO is localized in the represented group, and the hole transport ability decreases. When a high electron transporting substituent such as a group represented by Z is introduced in this state, the balance between the hole transporting ability and the electron transporting ability is maintained.

On the other hand, among the compounds represented by the general formula (1) of the present invention, the position of either R ⁴ or R ⁵ in the general formula (1) and the position of R ¹¹ or R ²³ in the general formula (2) Linked compounds are also preferred.

Any position among R ^{4 and} R ⁵ in the general formula (1) and any position among R ^{11 to} R ²³ in the general formula (2) are used for the coupling, so that in the general formula (2) HOMO is localized in the represented group, and the hole transport ability decreases. When a high electron transporting substituent such as a group represented by Z is introduced in this state, the balance between the hole transporting ability and the electron transporting ability is maintained.

  Although it does not specifically limit as a carbazole compound represented by the said General formula (1), The following examples are specifically mentioned. The following example is merely an example, and for example, a compound in which a group represented by the general formula (2) of a certain compound is appropriately combined with a group represented by the general formula (2) of another compound. Like these, it can be mentioned as a preferable example.

  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 bonding the phenyl group portion of phenylcarbazole and another carbazole skeleton include a method using a coupling reaction between a carbazole derivative and a halide using a palladium or copper catalyst, but are not limited thereto. It is not something. As an example, an example using 4- (9-carbazolyl) phenylboronic acid is shown below.

  In the above reaction, 9-phenyl-2- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) instead of 4- (9-carbazolyl) phenylboronic acid The reaction proceeds in the same manner even when -9H-carbazole is used. In this case, a structure in which a carbazole skeleton portion of phenylcarbazole and another carbazole skeleton are bonded to each other can be obtained.

  In the above reaction, the reaction proceeds in the same manner even when 4-hydroxycarbazole triflate is used instead of 3-bromocarbazole.

  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 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 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) hole transport layer / light emitting layer / electron transport layer and 2) light emitting layer / electron transport layer, 3) hole transport layer / light emitting layer, 4) Hole injection layer / hole transport layer / light emitting layer / electron transport layer, 5) hole transport layer / light emitting layer / electron transport layer / electron injection layer, 6) hole injection layer / hole transport layer / light emitting layer / A laminated structure such as an electron transport layer / electron injection layer is exemplified. Each of the layers may be either a single layer or a plurality of layers, and may be doped. 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 50 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. Of these, aluminum, calcium, 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 ^{26 to} R ³¹ may be the same or different and are selected from the group consisting of halogen, sulfonyl group, carbonyl group, nitro group, cyano group, and 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 a pyridine ring, a pyrimidine ring or a triazine ring, but is preferably used as a light emitting material because of its high light emitting performance. It is done. 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.

  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.

  In the present specification, the electron-accepting nitrogen 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 with the electron transport material.

  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 with the electron transport material. 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, Lithium quinolinol, which can be obtained at a low cost, is particularly preferred.

  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 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 liquid crystal display device, particularly a backlight for 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 [48] A mixed solution of 4.5 g of 4-hydroxycarbazole, 360 ml of dichloromethane and 3.0 g of diisopropylamine was cooled to 0 ° C. under a nitrogen stream, and 8.3 g of trifluoromethanesulfonic anhydride was added dropwise. After stirring this mixed solution at room temperature for 2 hours, 50 ml of water was poured and extracted with 50 ml of dichloromethane. The organic layer was washed twice with 50 ml of water, dried over magnesium sulfate and evaporated. After purification by silica gel column chromatography and vacuum drying, 7.0 g of 9H-carbazol-4-yl trifluoromethanesulfonate was obtained.

  Next, 3.2 g of 9H-carbazol-4-yltrifluoromethanesulfonate, 3.3 g of 9-phenylcarbazole-3-boronic acid, 22.6 ml of 1M aqueous sodium carbonate solution, 51 ml of 1,2-dimethoxyethane and bis (tri A mixed solution of 223 mg of phenylphosphine) palladium (II) dichloride was refluxed for 4 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 3.4 g of 9-phenyl-9H, 9'H-3,4'-bicarbazole.

  Also, a mixed solution of 10 g of 2,4,6-trichloropyrimidine, 13.3 g of phenylboronic acid, 163.5 ml of 2M aqueous sodium carbonate solution, 545 ml of 1,2-dimethoxyethane and bis (triphenylphosphine) palladium (II) dichloride was added. The mixture 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, a mixture of 1.4 g of 9-phenyl-9H, 9′H-3,4′-bicarbazole, 1.0 g of 2-chloro-4,6-diphenylpyrimidine, 460 mg of sodium-t-butoxide, and 34 ml of dehydrated toluene. The solution was stirred at room temperature under a nitrogen stream. To this mixed solution were added 0.47 g of tris (dibenzylideneacetone) dipalladium (0) and 0.27 g of tri-tert-butylphosphonium tetrafluoroborate, and the mixture was heated and stirred under reflux for 3 hours. The mixed solution was cooled to room temperature, filtered and evaporated. After purification by silica gel column chromatography and vacuum drying, 1.7 g of a pale yellow powder was obtained.

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 [48].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.02 (t, 1H), 7.30-7.70 (m, 20H), 8.04 (s, 1H), 8.15 (d , 1H), 8.33-8.39 (m, 5H), 8.91 (d, 1H), 8.97 (d, 1H).

This compound [48] 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 99.7% before sublimation purification and 99.9% after sublimation purification.

Synthesis example 2
Synthesis of Compound [2] 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 55% sodium hydride 0.29 g and dehydrated DMF 31 ml was stirred at room temperature under a nitrogen stream. To this mixed solution, a solution prepared by dissolving 2.5 g of 9-phenyl-9H, 9'H-3,4'-bicarbazole in 36 ml of dehydrated DMF was slowly added dropwise and stirred for 1 hour. Thereafter, 1.8 g of 2-chloro-4,6-diphenyl-1,3,5-triazine was dissolved in 18 ml of dehydrated DMF, slowly added dropwise and stirred for 12 hours, and then 50 ml of water was injected and stirred for 1 hour. And then 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, recrystallized twice with a mixed solvent of tetrahydrafuran and methanol, and vacuum dried to obtain 3.2 g of a 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 [2].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.06 (t, 1H), 7.28-7.73 (m, 20H), 8.15 (d, 1H), 8.37 (s , 1H), 8.78-8.82 (m, 4H), 9.14 (d, 1H), 9.21 (d, 1H).

This compound [2] 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 3
Synthesis of Compound [13] 1.6 g of 3-bromocarbazole, 2.1 g of 4- (9-carbazolyl) phenylboronic acid, 7.2 ml of 2M aqueous potassium carbonate solution, 33 ml of 1,2-dimethoxyethane, 29 mg of palladium acetate and tris ( A mixed solution of 100 mg of 2-methylphenyl) phosphine was refluxed for 6 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 dried under vacuum to obtain 2.0 g of 3- (4- (9H-carbazol-9-yl) phenyl) -9H-carbazole.

  Next, a mixed solution of 0.23 g of 55% sodium hydride and 24 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 2.0 g of 3- (4- (9H-carbazol-9-yl) phenyl) -9H-carbazole in 74 ml of dehydrated DMF and stirred for 1 hour. Thereafter, 1.4 g of 2-chloro-4,6-diphenyl-1,3,5-triazine was dissolved in 24 ml of dehydrated DMF, slowly added dropwise, stirred for 12 hours, and filtered. The obtained solid was washed with 150 ml of methanol and then filtered. The obtained solid was purified by silica gel column chromatography and vacuum-dried to obtain 2.9 g of white crystals.

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 [13].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.43-7.55 (m, 6H), 7.65-7.74 (m, 10H), 7.96-8.04 (m, 3H), 8.18-8.20 (m, 3H), 8.41 (m, 1H), 8.79-8.83 (d, 4H), 9.21-9.31 (m, 2H) .

This compound [13] 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 4
Synthesis of Compound [12] The compound [12] was synthesized in the same manner as in Synthesis Example 3 except that 3- (9H-carbazol-9-yl) phenylboronic acid was used instead of 4- (9-carbazolyl) phenylboronic acid. Crystals were obtained.

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 [12].
¹ H-NMR (DMSO-d6 (d = ppm)): 7.32 (td, 2H), 7.43-7.53 (m, 5H), 7.63-7.75 (m, 8H), 7.84 (t, 1H), 8.05-8.11 (m, 3H), 8.28-8.31 (d, 2H), 8.34-8.37 (d, 1H), 8. 67-8.71 (m, 5H), 9.07 (d, 1H), 9.14 (d, 1H).

This compound [12] was used as a light emitting device material after sublimation purification at about 300 ° C. under a pressure of 1 × 10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area% at a measurement wavelength of 254 nm) was 99.8% before sublimation purification and 99.9% after sublimation purification.

Synthesis example 5
Synthesis of Compound [38] 2- (3-Chlorophenyl) -4,6-diphenyl-1,3,5-triazine was used instead of 2-chloro-4,6-diphenyl-1,3,5-triazine. Was synthesized by the same method as in Synthesis Example 3 to obtain white crystals.

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 [38].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.32-7.71 (m, 18H), 7.79-7.89 (m, 3H), 7.98 (d, 2H), 8 .18 (d, 2H), 8.29 (d, 1H), 8.52 (s, 1H), 8.77-8.80 (m, 4H), 8.95 (m, 1H), 9. 04 (s, 1H).

This compound [36] was used as a light emitting device material after sublimation purification at about 370 ° 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 99.6% before sublimation purification and 99.9% after sublimation purification.

Synthesis Example 6
Synthesis of Compound [9] A mixed solution of 20 g of 2-bromonitrobenzene, 17 g of 4-chlorophenylboronic acid, 45 g of tripotassium phosphate, 6.9 g of tetrabutylammonium bromide, 480 mg of palladium acetate and 500 ml of dimethylformamide under a nitrogen stream at 130 ° C. And stirred for 5 hours. After cooling to room temperature, 100 ml of water was poured and extracted with 150 ml of toluene. The organic layer was washed twice with 100 ml of water, dried over magnesium sulfate and evaporated. After purification by silica gel column chromatography and vacuum drying, 22 g of 2- (4-chlorophenyl) nitrobenzene was obtained.

  Next, a mixed solution of 22 g of 2- (4-chlorophenyl) nitrobenzene, 61 g of triphenylphosphine and 190 ml of o-dichlorobenzene was refluxed for 6 hours under a nitrogen stream. After cooling to room temperature, o-dichlorobenzene was distilled off under reduced pressure and purified by silica gel column chromatography. After vacuum drying, 17.7 g of 2-chloro-9H-carbazole was obtained.

  Next, a mixed solution of 17.7 g of 2-chloro-9H-carbazole, 22 g of iodobenzene, 20 g of copper powder, 43 g of potassium carbonate, and 200 ml of dimethylformamide was heated and stirred at 140 ° C. for 16 hours in a nitrogen stream. After cooling to room temperature, 50 ml of ethyl acetate was added and filtered through celite. A saturated aqueous ammonium chloride solution was added to the obtained filtrate and stirred for a while, followed by extraction with ethyl acetate and hexane. After drying with magnesium sulfate, evaporation was performed. After purification by silica gel column chromatography and vacuum drying, 14 g of 2-chloro-9-phenyl-9H-carbazole was obtained.

  Next, 14 g of 2-chloro-9-phenyl-9H-carbazole, 15.4 g of bis (pinacolato) diboron, 14.8 g of potassium acetate, 100 ml of dioxane, 0.58 g of tris (dibenzylideneacetone) dipalladium (0) and 2 -A mixed solution of 961 mg of dicyclohexylphosphino-2'4'6'-triisopropylbiphenyl was refluxed for 7 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, dried in vacuo, and then 9-phenyl-2- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)- 16 g of 9H-carbazole was obtained.

  Next, 4.0 g of 3-bromocarbazole, 9-phenyl-2- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9H-carbazole 6.6 g, 2M A mixed solution of 18 ml of an aqueous potassium carbonate solution, 80 ml of 1,2-dimethoxyethane, 72 mg of palladium acetate and 243 mg of tris (2-methylphenyl) phosphine was refluxed for 6 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 5.2 g of 9-phenyl-9H, 9'H-2,3'-bicarbazole.

  Next, a mixed solution of 0.24 g of 55% sodium hydride and 24 ml of dehydrated DMF was stirred at room temperature under a nitrogen stream. A solution prepared by dissolving 2.0 g of 9-phenyl-9H, 9'H-2,3'-bicarbazole in 24 ml of dehydrated DMF was slowly added dropwise to this mixed solution and stirred for 1 hour. Thereafter, 1.4 g of 2-chloro-4,6-diphenyl-1,3,5-triazine was dissolved in 24 ml of dehydrated DMF, slowly added dropwise, stirred for 12 hours, and filtered. The obtained solid was washed with 150 ml of methanol and then filtered. The obtained solid was purified by silica gel column chromatography and vacuum dried to obtain 3.0 g of white crystals.

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 [9].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.30-7.36 (m, 1H), 7.43-7.56 (m, 4H), 7.61-7.76 (m, 13H), 7.91 (dd, 1H), 8.14-8.33 (m, 4H), 8.76-8.80 (m, 4H), 9.18-9.23 (m, 2H) .

This compound [9] was used as a light emitting device material after sublimation purification at about 340 ° 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 7
Synthesis of Compound [20] Synthesis was performed in the same manner as in Synthesis Example 3 except that 2-bromocarbazole was used instead of 3-bromocarbazole to obtain white crystals.

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 [20].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.26-7.36 (m, 2H), 7.45-7.84 (m, 15H), 8.08-8.21 (m, 6H), 8.80-8.83 (m, 4H), 9.24-9.27 (d, 1H), 9.76 (s, 1H).

This compound [20] was used as a light emitting device material after sublimation purification at about 300 ° C. under a pressure of 1 × 10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area% at a measurement wavelength of 254 nm) was 99.7% before sublimation purification and 99.9% 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 [13] 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% by weight 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 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 3000 hours.

Examples or Reference Examples 2 to 6
A light emitting device was fabricated in the same manner as in Example 1 except that the materials listed in Table 1 were used as the host material. The results of each example are shown in Table 1.

Comparative Examples 1-6
A light emitting device was fabricated in the same manner as in Example 1 except that H-1 to H-6 represented by the following formula was used as the host material. The results of each comparative example are shown in Table 1.

Example 7
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. HI-1 was vapor-deposited by 10 nm as a hole injection layer by the resistance heating method. Next, 80 nm of HT-1 was vapor-deposited as a 1st positive hole transport layer. Next, 10 nm of HT-2 was deposited as a second hole transport layer. Next, as a light emitting layer, the compound [13] was used as the host material, the compound D-2 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, a layer in which an organic compound (E-2) and a donor compound (Liq: lithium quinolinol) are mixed at a deposition rate ratio of 1: 1 (= 0.05 nm / s: 0.05 nm / s) is 35 nm as an electron transport layer. Laminated to a thickness of

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, 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 , green light emission with a luminous efficiency of 50.0 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 5000 hours. Compounds HT-1, HT-2, and D-2 are the compounds shown below.

Examples 8-10
A light emitting device was fabricated and evaluated in the same manner as in Example 7 except that the materials listed in Table 2 were used as the host material. The results are shown in Table 2.

Comparative Examples 7-11
A light emitting device was fabricated and evaluated in the same manner as in Example 7 except that the compounds described in Table 2 were used as the host material. The results are shown in Table 2.

Examples 11-14
As a hole injection layer, compound HT-1 and compound HI-2 are used instead of compound HI-1, and the doping concentration of compound HI-2 is 3% by weight with respect to compound HT-1, so that the deposition is 10 nm. A light emitting device was fabricated in the same manner as in Example 7 except that. The results are shown in Table 2. HI-2 is a compound shown below.

Examples or Reference Examples 15 to 19
Instead of compound [13], a mixed host of compound [13] and compound H-7 (co-deposited film of compound [13] and compound H-7 was deposited at a deposition rate ratio of 1: 1 instead of compound [13]. A light-emitting element was fabricated in the same manner as in Examples 11 to 14 except that (deposited) was used. The results are shown in Table 2. H-7, HT-3, and HT-4 are the compounds shown below.

Examples 20-23
A light emitting device was produced in the same manner as in Examples 11 to 14 except that Compound HI-3 was used instead of Compound HI-1 as the hole injection layer. The results are shown in Table 2. HI-3 is a compound shown below.

Examples or Reference Examples 24-26
A light emitting device was produced in the same manner as in Example 11 except that the material described in Table 2 was used instead of the layer in which Compound E-2 and a donor compound (Liq: lithium quinolinol) were mixed as the electron transport layer. The results are shown in Table 2. E-3 to E-5 are the compounds shown below.

Example 27
As an electron transport layer, instead of a layer in which compound E-2 and a donor compound (Liq: lithium quinolinol) are mixed, compound E-2 and compound E-1 are stacked at a film thickness ratio of 1: 1 to a thickness of 35 nm. A light emitting device was fabricated in the same manner as in Example 11 except that the above was used. The results are shown in Table 2.

Example 28
As an electron transport layer, instead of a layer in which compound E-2 and a donor compound (Liq: lithium quinolinol) are mixed, compound [15] and compound E-1 are laminated to a thickness of 35 nm at a film thickness ratio of 1: 1. A light emitting device was fabricated in the same manner as in Example 11 except for using the above. The results are shown in Table 2.

Reference Example 29
As an electron transport layer, instead of a layer in which compound E-2 and a donor compound (Liq: lithium quinolinol) are mixed, compound E-4 and compound E-1 are laminated at a film thickness ratio of 1: 1 to a thickness of 35 nm. A light emitting device was fabricated in the same manner as in Example 11 except that the above was used. The results are shown in Table 2.

Reference examples 30-31
Vapor deposition rate ratio of compound E-4, compound E-1 and donor compound (Li: metallic lithium) instead of the layer in which compound E-2 and donor compound (Liq: lithium quinolinol) are mixed as the electron transport layer A light-emitting element was fabricated in the same manner as in Example 7 except that a layer mixed at 1: 1 (= 0.05 nm / s: 0.05 nm / s) was laminated to a thickness of 35 nm at a film thickness ratio of 1: 1. did. The results are shown in Table 2.

Claims (10)

A light-emitting element material comprising a compound having a carbazole skeleton represented by the following general formula (1), wherein the compound contains only two carbazole skeletons in a molecule.

(R ^{1 to} R ⁸ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl It consists of a thioether group, an aryl group, a heteroaryl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a silyl group, —P (═O) R ⁹ R ¹⁰ and the following general formula (2). R ⁹ and R ¹⁰ are an aryl group or a heteroaryl group, and at least one of R ^{1 to} R ⁸ is a group represented by the following general formula (2), and is selected from the group (2) .Y connecting with any position of ^R 19 ^{to R 23} in) is a single bond or an arylene group .Z the following formula Is a group represented by 3).

(R ^{11 to} R ²³ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, an aryl group, a heteroaryl group, halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, ^{.R 24} of chosen from the group consisting of silyl group, and ^{-P (= O) R 24 R} 25 And R ²⁵ represents an aryl group or a heteroaryl group, and R ^{19 to} R ²³ may form a ring with adjacent substituents, provided that any one of R ^{19 to} R ²³ has the general formula ( connecting with any of the positions of ^R 1 to R ⁸ in 1). ^Further, R 11 ^{to R 23} in general formula ( ) Except when connected to any position of R ¹ to R ⁸ in the condensed ring structure containing a nitrogen atom, a condensed ring structure containing an oxygen atom, not including the condensed ring structure and an amine structure containing a sulfur atom In addition, the position of R ³ or R ⁶ in the general formula (1) and the position of R ¹³ or R ¹⁶ in the general formula (2) are not linked.)

(X ^{1 to} X ³ represent CH or N, and at least one of X ^{1 to} X ³ is a nitrogen atom. Ar ¹ and Ar ² may be the same or different, and each has a condensed ring structure. Not a substituted or unsubstituted aryl group or heteroaryl group.) 2. The light emission according to claim 1, wherein any one position of R ⁴ or R ⁵ in the general formula (1) is linked to any one position of R ^{19 to} R ²³ in the general formula (2). Element material. The light emitting device material according to claim 1, wherein Y is a single bond. The light emitting device material according to any one of claims 1 to 3, wherein Ar ¹ and Ar ² may be the same or different and each is a substituted or unsubstituted phenyl group. R < ¹ > -R < ²³ > may be same or different, respectively, and is hydrogen, an alkyl group, an aryl group, or heteroaryl group, The light emitting element material in any one of Claims 1-4. A light-emitting element having at least a light-emitting layer between an anode and a cathode and emitting light by electric energy, wherein the light-emitting element contains the light-emitting element material according to claim 1. . The light emitting device according to claim 6, wherein at least a light emitting layer exists between the anode and the cathode and emits light by electric energy, and the light emitting layer contains a triplet light emitting material. The light emitting element according to claim 6 or 7, wherein the light emitting layer has a host material and a dopant material, and the light emitting element material according to any one of claims 1 to 5 is a host material. An element that has at least a hole transport layer and a light emitting layer between an anode and a cathode and emits light by electric energy, wherein a hole injection layer exists between the hole transport layer and the anode, The light emitting element in any one of Claims 6-8 containing an acceptor property compound. There is at least an electron transport layer between the light-emitting layer and the cathode, and the electron transport layer contains an electron-accepting nitrogen, and is further composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus. The light emitting device according to claim 6, comprising a compound having an aryl ring structure.