TWI521044B - Light-emitting element material and light-emitting element - Google Patents

Description

Light-emitting element material and light-emitting element

The present invention relates to a light-emitting element that converts electrical energy into light and materials used in the light-emitting element. The invention can be used in the fields of display elements, flat panel displays, backlights, lighting, interior decoration, signs, signboards, electronic cameras and optical signal generators.

In recent years, research on organic thin film light-emitting elements in which electrons injected from a cathode and holes injected from an anode are recombined when recombined in an organic fluorescent body sandwiched by two electrodes are actively being carried out. Light-emitting element. The light-emitting element is characterized by a thin type, high-intensity light emission at a low driving voltage, and multi-color light emission by selecting a fluorescent material, and is attracting attention. Since C.W. Tang et al. of Kodak Company disclosed that organic thin film light-emitting elements emit light with high brightness, many research institutions are conducting research on organic thin film light-emitting elements.

Further, since the organic thin film light-emitting element can obtain various luminescent colors by using various fluorescent materials for the light-emitting layer, practical research on displays and the like is prevailing. Among the luminescent materials of the three primary colors, the research of green luminescent materials is the most active, and the red luminescent materials and the blue luminescent materials are currently being researched for the purpose of improving the characteristics.

The organic thin film light-emitting element requires an improvement in luminous efficiency, a reduction in driving voltage, and an improvement in durability. However, when the luminous efficiency is low, the output of an image requiring high luminance cannot be performed, and the power consumption for outputting the desired luminance is increased. For example, in order to improve luminous efficiency, development has been made Various luminescent materials or electron transporting materials which are basic skeletons (see Patent Documents 1 to 4).

Prior technical literature

Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2004-91350

Patent Document 2: Japanese Patent Laid-Open Publication No. 2010-215759

Patent Document 3: Japanese Patent Laid-Open Publication No. 2004-277377

Patent Document 4: Japanese Patent Laid-Open Publication No. 2008-208065

However, in previously known materials, the coexistence of low voltage driving and high luminous efficiency is not sufficient. An object of the present invention is to solve the problems of the prior art and to provide a light-emitting element material which can realize an organic thin film light-emitting element which has high luminous efficiency and a low driving voltage, and a light-emitting element using the same.

The present invention is a light-emitting element material comprising a compound represented by the following formula (1).

In the formula, Y is a group represented by the following formula (2); Ar ¹ is a group represented by the following formula (3); L ¹ is a single bond or is selected from a nucleus carbon number of 5 to 12 a substituted or unsubstituted extended aryl group, and a substituted or unsubstituted heteroaryl group; L ² is a substituted or unsubstituted aryl group having a nucleus number of 5 to 12 a group in the substituted or unsubstituted heteroaryl group; Ar ² is a group containing only an aromatic heterocyclic group containing an electron-accepting nitrogen which is unsubstituted or substituted with an alkyl group or a cycloalkyl group; n is an integer from 1 to 5; n Ar ² may be the same or different.

R ¹ to R ¹⁰ may be the same as or different from each other and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, heterocyclic, alkenyl, cycloalkenyl, alkynyl, alkoxy, alkylthio, aryl ether. the group consisting of R ¹¹ R ¹² in the group, aryl thioether group, aryl, heteroaryl, halo, carbonyl, carboxyl, oxycarbonyl group, carbamoyl acyl and -P (= O); R ¹¹ and R ¹² is selected from aryl and heteroaryl groups are groups; R ¹ ~ R ¹² may be substituted by groups adjacent to each other to form a ring; wherein any one of ¹ ~ R ⁸ R to L ¹ for the link, and thus, for any of the remaining connected to the L ^2.

R ¹³ to R ²¹ may be the same as or different from each other, and are a group selected from the group consisting of hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an aryl group, and a heteroaryl group. R ¹³ to R ²¹ may form a ring by each other by adjacent substituents. Here, any one of R ¹³ to R ²¹ is used for the linkage with L ¹ .

According to the present invention, it is possible to provide an organic thin film light-emitting element which has high luminous efficiency and low driving voltage.

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

In the formula, Y is a group represented by the following formula (2), and Ar ¹ is a group represented by the following formula (3). L ¹ is a single bond or a group selected from a substituted or unsubstituted extended aryl group having a core number of 5 to 12 and a substituted or unsubstituted heteroaryl group. L ² is a group selected from a substituted or unsubstituted extended aryl group having a nucleus number of 5 to 12 and a substituted or unsubstituted heteroaryl group. Ar ² is a group containing only an aromatic heterocyclic group containing an electron-accepting nitrogen which is unsubstituted or substituted with an alkyl group or a cycloalkyl group. n is an integer from 1 to 5. The n Ar ^{2 's} may be the same or different.

[Chemical 5]

R ¹ to R ¹⁰ may be the same as or different from each other and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, heterocyclic, alkenyl, cycloalkenyl, alkynyl, alkoxy, alkylthio, aryl ether. a group in the group consisting of a aryl group, an aryl sulfide group, an aryl group, a heteroaryl group, a halogen, a carbonyl group, a carboxyl group, an oxycarbonyl group, an amine carbenyl group, and -P(=O)R ¹¹ R ¹² . R ¹¹ and R ¹² are a group selected from the group consisting of an aryl group and a heteroaryl group. R ¹ to R ¹² may form a ring by each other by adjacent substituents. Here, any one of R ¹ to R ⁸ is used for the connection with L ¹ , and the other one is used for the connection with L ² . Here, any one of R ¹ to R ⁸ for linking with L ¹ means that the position of any one of R ¹ to R ⁸ represented by the formula (2) is directly bonded to L ¹ . Knot. The same is true for L ² .

R ¹³ to R ²¹ may be the same as or different from each other, and are a group selected from the group consisting of hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an aryl group, and a heteroaryl group. R ¹³ to R ²¹ may form a ring by each other by adjacent substituents. Among them, any of R ¹³ to R ²¹ is used for the linkage with L ¹ . Here, any one of R ¹³ to R ²¹ for linking with L ¹ means that the position of any one of R ¹³ to R ²¹ represented by the formula (3) is directly bonded to L ¹ . Knot.

In all of the above groups, hydrogen may also be heavy hydrogen. Further, the alkyl group means, for example, a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a second butyl group or a t-butyl group, which may have a substituent or may not Has a substituent. The additional substituent at the time of substitution is not particularly limited, and examples thereof include an alkyl group, an aryl group, and a heteroaryl group, and the same points are also used in the following description. In addition, the number of carbon atoms of the alkyl group is not particularly limited, and from the viewpoint of availability and cost, it is preferably 1 or more and 20 or less, more preferably 1 or more and 8 or less.

The cycloalkyl group means, for example, a saturated alicyclic hydrocarbon group such as a cyclopropyl group, a cyclohexyl group, a decyl group or an adamantyl group, and may have a substituent or may have no substituent. The carbon number of the alkyl moiety is not particularly limited, but is preferably in the range of 3 or more and 20 or less.

The heterocyclic group is, for example, an aliphatic ring having an atom other than carbon in a ring such as a pyran ring, a piperidine ring or a cyclic decylamine, and may have a substituent or may have no substituent. The carbon number of the heterocyclic group is not particularly limited, but is preferably in the range of 2 or more and 20 or less.

The alkenyl group is, for example, an unsaturated aliphatic hydrocarbon group having a double bond such as a vinyl group, an allyl group or a butadienyl group, and may have a substituent or may have no substituent. The carbon number of the alkenyl group is not particularly limited, but is preferably in the range of 2 or more and 20 or less.

By cycloalkenyl, for example, it is meant cyclopentenyl, cyclopentadienyl, cyclohexyl An unsaturated alicyclic hydrocarbon group having a double bond such as an alkenyl group, which may have a substituent or may have no substituent.

The alkynyl group is, for example, an unsaturated aliphatic hydrocarbon group having a triple bond such as an ethynyl group, and may have a substituent or may have no substituent. The carbon number of the alkynyl group is not particularly limited, but is preferably in the range of 2 or more and 20 or less.

The alkoxy group is, for example, a functional group in which an aliphatic hydrocarbon group is bonded via an ether bond such as a methoxy group, an ethoxy group or a propoxy group, and the aliphatic hydrocarbon group may have a substituent or may have no substituent. The carbon number of the alkoxy group is not particularly limited, but is preferably in the range of 1 or more and 20 or less.

The alkylthio group means that the oxygen atom of the ether bond of the alkoxy group is substituted by a sulfur atom. The alkylthio group may have a substituent or may have no substituent. The carbon number of the alkylthio group is not particularly limited, but is preferably in the range of 1 or more and 20 or less.

The aryl ether group is, for example, a functional group in which an aromatic hydrocarbon group is bonded via an ether bond such as a phenoxy group, and the aromatic hydrocarbon group may have a substituent or may have no substituent. The carbon number of the aryl ether group is not particularly limited, but is preferably in the range of 6 or more and 40 or less.

The aryl sulfide group refers to an oxygen atom of an ether bond of an aryl ether group which is substituted by a sulfur atom. The aromatic hydrocarbon group in the aryl ether group may have a substituent or may have no substituent. The carbon number of the aryl ether group is not particularly limited, but is preferably in the range of 6 or more and 40 or less.

The aryl group means, for example, an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group or a fluorenyl group. The aryl group may have a substituent or may have no substituent. The carbon number of the aryl group is not particularly limited, but is preferably 6 or more. The range below 40.

By heteroaryl, it is meant furyl, phenylthio, pyridyl, quinolyl, isoquinolinyl, pyrazinyl, pyrimidinyl, naphthyridinyl, benzofuranyl, benzophenylthio, fluorene A cyclic aromatic group having one or more atoms other than carbon in the ring such as a dibenzofuranyl group, a dibenzophenylthio group or a carbazolyl group, which may be unsubstituted or substituted. The carbon number of the heteroaryl group is not particularly limited, but is preferably in the range of 2 or more and 30 or less.

By halogen, it means an atom selected from the group consisting of fluorine, chlorine, bromine and iodine.

The carbonyl group, the carboxyl group, the oxycarbonyl group, the aminecarbamyl group and the phosphine oxide group may have a substituent or may have no substituent. Here, examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group, and these substituents may be further substituted.

The aryl group means a divalent group derived from an aromatic hydrocarbon group such as a phenyl group, a naphthyl group or a biphenyl group, and may have a substituent or may have no substituent. When L ¹ or L ² of the formula (1) is an extended aryl group, the number of core carbon atoms is preferably in the range of 5 or more and 12 or less. Specific examples of the aryl group include a 1,4-phenylene group, a 1,3-phenylene group, a 1,2-phenylene group, a 4,4'-linked phenyl group, and a 4,3' group. - a stretched phenyl group, a 3,3'-stretched phenyl group, a 1,4-strendyl group, a 1,5-anthranyl group, a 2,5-anthranyl group, a 2,6-anthranyl group, 2, 7-streptyl group and the like. More preferably, it is a 1,4-phenylene group.

When a ring is formed by contiguous substituents, any two adjacent substituents (for example, R ² and R ^{3 of the} formula (2)) may be bonded to each other to form a conjugated or non-conjugated fused ring. . The constituent element of the condensed ring may contain, in addition to carbon, an atom selected from nitrogen, oxygen, sulfur, phosphorus, and ruthenium, and may also be condensed with other rings.

The term "heteroaryl" means having one or more carbons other than a pyridyl group, a quinolyl group, a pyrazinyl group, a naphthyridinyl group, a dibenzofuranyl group, a dibenzophenylthio group or a carbazolyl group. The divalent group derived from the aromatic group of the atom may have a substituent or may have no substituent. The carbon number of the heteroaryl group is not particularly limited, but is preferably in the range of 2 to 30.

The aromatic heterocyclic group containing an electron-accepting nitrogen is a cyclic aromatic group having one or more electron-accepting nitrogen atoms in the ring as an atom other than carbon. The number of electron-accepting nitrogen contained in the aromatic heterocyclic group containing electron-accepting nitrogen is not particularly limited, but is preferably in the range of 1 or more and 6 or less. Furthermore, the groups may also be substituted by an alkyl group or a cycloalkyl group.

The electron accepting nitrogen as used herein refers to a nitrogen atom having a multiple bond formed between adjacent atoms. Since the nitrogen atom has high anion property, the multiple bond has electron acceptability. Therefore, an aromatic heterocyclic ring containing an electron-accepting nitrogen has high electron affinity.

Examples of the aromatic heterocyclic group containing electron-accepting nitrogen include a pyridyl group, a quinolyl group, an isoquinolyl group, a quinoxalinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, and a phenanthryl group. Imidazopyridyl, triazinyl, acridinyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, bipyridyl, tertidapyridyl and the like. The carbon number of the aromatic heterocyclic group containing electron-accepting nitrogen is not particularly limited, but is preferably in the range of 2 or more and 30 or less. The linking position of the aromatic heterocyclic group containing an electron-accepting nitrogen may be any moiety. For example, in the case of a pyridyl group, it may be any of a 2-pyridyl group, a 3-pyridyl group and a 4-pyridyl group.

By the general formula (1) compound represented by Ar ² is a group containing only an unsubstituted or alkyl-substituted cycloalkyl or an electron accepting aromatic heterocyclic group containing a nitrogen, it contains an electron-accepting nitrogen An aromatic heterocyclic group exists on the outer side (end) of the molecule. Therefore, when the compound represented by the general formula (1) is used for the electron transport layer, it is easier to receive electrons from the cathode, and the driving voltage of the light-emitting element can be lowered. Further, since the supply of electrons toward the light-emitting layer is increased, the probability of recombination of electrons and holes is increased, and thus the light-emitting efficiency of the light-emitting element is improved.

Further, Ar ² is a group containing only an aromatic heterocyclic group containing an electron-accepting nitrogen which is unsubstituted or substituted with an alkyl group or a cycloalkyl group, and of course includes Ar ² as an unsubstituted aromatic heterocyclic group. In addition, in addition to the above, Ar ² is a substituted aromatic heterocyclic group, and the substituent is selected from the group consisting of an alkyl group, a cycloalkyl group, and an aromatic heterocyclic group containing an electron-accepting nitrogen. Examples of the latter include a bipyridyl group or a bis(pyridyl)pyridyl group (all pyridyl groups having a pyridyl group as an electron-accepting nitrogen-containing aromatic heterocyclic group as a substituent). Further, the group containing only the aromatic heterocyclic group containing electron-accepting nitrogen may be substituted by an alkyl group or a cycloalkyl group, but may not be substituted by an aromatic group containing no electron-accepting nitrogen. When the substituent is an alkyl group or a cycloalkyl group, since the conjugate does not expand in these groups, it does not greatly affect the high electron affinity of the aromatic heterocyclic ring containing electron-accepting nitrogen. On the other hand, when an aromatic heterocyclic group containing an electron-accepting nitrogen is substituted with an aromatic group containing no electron-accepting nitrogen such as an aryl group, the conjugation is extended to the substituents, so that electron-accepting nitrogen is contained. The high electron affinity of the aromatic heterocyclic ring is impaired. That is, even if the group containing only the aromatic heterocyclic group containing an electron-accepting nitrogen is substituted by an alkyl group or a cycloalkyl group, the above effect is not impaired, but when it is substituted by an aromatic group containing no electron-accepting nitrogen. The above effects are impaired.

More specifically, Ar ^{2 is} preferably selected from the group consisting of the groups shown below.

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In the above, it represents Ar ² and L the solid line bonding position ² is through ring-constituting each of the multi-membered ring is depicted, which represents Ar ² and L are bonded at position ² can be any Ar multi-membered ² ring One location. For example, in the case of a pyridyl group, it means any of 2-pyridyl, 3-pyridyl and 4-pyridyl, and in the case of a quinolyl group, it can be 2-quinolyl, 3- Any one of a quinolyl group, a 4-quinolyl group, a 5-quinolyl group, a 6-quinolyl group, a 7-quinolyl group, and an 8-quinolyl group. Further, in the case where a plurality of ring groups are bonded to a bipyridyl group or the like, the bond is drawn from one ring, but it may be bonded by another ring.

In addition, the groups exemplified above may also be substituted by an alkyl group or a cycloalkyl group. Preferably, it is substituted by methyl, ethyl, propyl, butyl or cyclohexyl.

Ar ^{2 is} preferably pyridyl, quinolyl, isoquinolyl, quinoxalinyl, pyrimidinyl, morpholinyl, bipyridyl, terpyridine, acridinyl, benzo[d]imidazolyl, imidazole And [1,2-a]pyridyl, and a group in which these groups are substituted by an alkyl group or a cycloalkyl group, preferably a methyl group or a cyclohexyl group. More specifically, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-quinolyl, 3-quinolyl, 6-quinolyl, 1-isoquinolinyl, 3-iso are mentioned Quinolinyl, 2-quinoxalinyl, 5-pyrimidinyl, 2-morpholinyl, 1-benzo[d]imidazolyl, 2-benzo[d]imidazolyl, 2-imidazo[1,2 -a] pyridyl, 3-imidazo[1,2-a]pyridyl, 3-methyl-2-pyridyl, 4-methyl-2-pyridyl, 5-methyl-2-pyridyl, 6-methyl-2-pyridyl, 2-methyl-3-pyridyl, 4-methyl-3-pyridyl, 5-methyl-3-pyridyl, 6-methyl-3-pyridyl, 2-methyl-4-pyridyl, 3-methyl-4-pyridyl, 4-methyl-2-quinolyl, etc., more preferably 2-pyridyl, 3-pyridyl, 4-pyridine Base.

The compound represented by the formula (1) has both an anthracene skeleton and an aromatic heterocyclic ring containing an electron-accepting nitrogen in the molecule, and has high electron transport properties and electrochemical stability of the anthracene skeleton, and electron acceptability. High electron acceptability of nitrogen aromatic heterocycles. Thereby, the compound represented by the general formula (1) exhibits high electron injecting and transporting ability.

The compound represented by the formula (1) has a high carrier mobility and a good carrier balance by having one to five aromatic heterocyclic rings Ar ² containing an electron-accepting nitrogen in the molecule. Thereby, the compound represented by the general formula (1) can improve the luminous efficiency of the light-emitting element. Further, since the compound represented by the formula (1) has high heat resistance, the durability of the light-emitting element can be improved. In the case where the effect of lowering the crystallinity and the substituent is remarkably exhibited, it is more preferable that the number of Ar ² is one or two, and particularly preferably the number of Ar ² is one. When Ar ² is two or more, Ar ² may be the same or different.

Further, the compound represented by the formula (1) has an anthracene skeleton and a carbazole group in the molecule, thereby suppressing the stacking between the molecules, thereby stabilizing the film. In addition, the electrochemical stability of the hole is enhanced by including a carbazole group having hole tolerance. Thereby, the compound represented by the general formula (1) exhibits higher electron injection transport ability.

Further, it is desirable that R ⁷ in the formula (2) is used for the linkage with L ¹ . The conjugated system is easily enlarged at the positions of R ² and R ⁷ , and the conjugated system is efficiently expanded by the use of R ⁷ for the linkage with L ¹ . Thereby, the electrochemical property of the compound represented by the general formula (1) becomes stable, and the electron transport property is improved, so that a higher electron injection transport ability is exhibited.

Further, it is desirable that R ² in the formula (2) is used for the linkage with L ² . The conjugated system is easily enlarged at the positions of R ² and R ⁷ , and the conjugated system is efficiently expanded by the use of R ² for the linkage with L ² . Thereby, the electrochemical property of the compound represented by the general formula (1) becomes stable, and the electron transport property is improved, so that a higher electron injection transport ability is exhibited.

Further, it is preferred that R ¹⁵ , R ¹⁸ or R ²¹ in the formula (3) is used for the linkage with L ¹ . Since the position of R ¹⁵ , R ¹⁸ and R ²¹ is not resistant to oxidation, the carbazole is bonded to the linking group, whereby the electrochemical property of the compound represented by the general formula (1) becomes stable and appears to be more High electron injection transmission capability.

In addition, for example, the term "R ⁷ for linking to L ^{1 "} means that the position of R ⁷ of the benzene ring represented by the formula (2) is directly bonded to the group represented by the linking group L ¹ .

Further, L ^{1 is} preferably a substituted or unsubstituted extended aryl group having a core carbon number of 5 to 12. The carbazole gene is not resistant to oxidation, so that the electrochemical properties become more stable by bonding with an aryl group as compared to direct bonding to the fluorene skeleton. Thereby, a multiplication effect is produced with the high electron transport property of the ruthenium skeleton, and a higher electron injection transport capability is exhibited.

Further, L ² nuclear carbon atoms is preferably 5 to 12 by a substituted or unsubstituted arylene group. Since the aromatic heterocyclic ring containing electron-accepting nitrogen is not resistant to oxidation, the electrochemical property is more stabilized by bonding by stretching the aryl group as compared with the direct bonding to the fluorene skeleton. Thereby, a multiplication effect is produced with the high electron transport property of the ruthenium skeleton, and a higher electron injection transport capability is exhibited.

In the compound represented by the formula (1), R ¹ to R ²¹ are preferably a group selected from the group consisting of hydrogen, an alkyl group, a cycloalkyl group, an aryl group and a heteroaryl group. Further, R ⁹ to R ¹⁰ are preferably an alkyl group, a cycloalkyl group, an aryl group or a heteroaryl group in the above group. As R ²¹ , among the above groups, an aryl group or a heteroaryl group is preferred.

The compound represented by the above formula (1) is not particularly limited, and specific examples thereof include the following examples.

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A well-known method can be used for the synthesis of the compound represented by the formula (1). The method of introducing a carbazolyl group into an anthracene skeleton may, for example, be a method of using a coupling reaction of a halogenated hydrazine derivative and a substituted or unsubstituted carbazole boronic acid under a palladium catalyst or a nickel catalyst, but is not limited thereto. In the methods. Further, the method of introducing an aromatic heterocyclic ring containing electron-accepting nitrogen into the oxime skeleton is also the same as described above, and examples thereof include a ruthenium halide derivative and an aromatic group containing electron-accepting nitrogen under a palladium catalyst or a nickel catalyst. The method of coupling reaction of a heterocyclic boric acid is not limited to these methods. Further, when an oxazolyl group or an aromatic heterocyclic ring containing an electron-accepting nitrogen is introduced into the oxime skeleton via an aryl group, an aryl group substituted with an oxazolyl group or an aromatic heterocyclic ring containing an electron-accepting nitrogen may also be used. Boric acid. Further, a boric acid ester may be used instead of the above various boric acids.

The compound represented by the general formula (1) can be used as a light-emitting element material. Here, the term "light-emitting element material" means a material used for any layer of a light-emitting element, as described below, except for being selected from a hole transport layer, a light-emitting layer, and an electron transfer. In addition to the materials in the layers of the transport layer, materials for the protective film of the cathode are also included. By using the compound represented by the general formula (1) for any layer of the light-emitting element, a high light-emitting efficiency can be obtained, and a light-emitting element having a low driving voltage can be obtained.

The compound represented by the formula (1) is preferably a light-emitting layer or an electron transport layer for a light-emitting element because of its high electron injecting and transporting ability, luminous efficiency, and film stability. In particular, it is preferably used for an electron transport layer because of its excellent electron injection transport capability.

Next, the light-emitting element will be described in detail. The light emitting element has an anode, a cathode, and an organic layer interposed between the anode and the cathode. The organic layer includes at least a light-emitting layer that emits light by electrical energy.

The organic layer includes, in addition to the configuration including only the light-emitting layer, a laminate structure such as 1) a hole transport layer/light-emitting layer/electron transport layer, 2) a light-emitting layer/electron transport layer, and 3) a hole transport layer/light-emitting layer. . Further, each of the above layers may be either a single layer or a plurality of layers. When the hole transport layer and the electron transport layer have a plurality of layers, the layers on the side in contact with the electrodes may be referred to as a hole injection layer and an electron injection layer, respectively. However, in the following description, the holes are not particularly mentioned. The implant material is contained in the hole transport material, and the electron injection material is contained in the electron transport material.

Further, in order to maintain the mechanical strength of the light-emitting element, it is preferable to form the light-emitting element on the substrate. As the substrate, a glass substrate such as soda glass or alkali-free glass can be suitably used. The thickness of the glass substrate is not particularly limited as long as it is sufficient to maintain mechanical strength. Therefore, it is sufficient if it is 0.5 mm or more. As for the material of the glass, it is preferable that the amount of eluted ions from the glass is small, so that it is preferably an alkali-free glass. Alternatively, a soda lime glass to which a barrier coating layer of SiO ₂ or the like is applied is also commercially available, and thus the soda lime glass can also be used. Further, the substrate need not be glass, and for example, a plastic substrate can also be used.

In the light-emitting element, the anode and the cathode have a function of supplying a current sufficient to cause the element to emit light. In order to derive light, it is desirable that at least one of the anode and the cathode be transparent or translucent. Usually, the anode formed on the substrate is set as a transparent electrode.

Preferably, the material used in the anode is a material that can efficiently inject holes into the organic layer and is transparent or translucent for light extraction. Examples of the material used for the anode include conductive metal oxides such as tin oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (Indium Zinc Oxide, IZO); gold, silver, and chromium. Such as a metal; an inorganic conductive compound such as copper iodide or copper sulfide; a conductive polymer such as polythiophene, polypyrrole or polyaniline. Although not particularly limited, it is particularly desirable to use ITO glass or Nesep glass. The electrode materials may be used singly or in combination of a plurality of materials. The electric resistance of the transparent electrode is not limited as long as it can supply a current sufficient to cause the element to emit light. However, from the viewpoint of power consumption of the element, it is preferable to have a low electric resistance. For example, an ITO substrate having a surface resistance of 300 Ω/□ or less can be sufficiently used as an element electrode. However, a substrate of about 10 Ω/□ can be supplied at present. Therefore, it is particularly preferable to use a substrate having a low resistance of 20 Ω/□ or less. The thickness of the anode can be arbitrarily selected in accordance with the resistance value, but it is often used between 100 nm and 300 nm.

The material used in the cathode can be efficiently injected into the electron as long as it is The substance of the light-emitting layer is not particularly limited. Generally, metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, or alloys of such metals with low work function metals such as lithium, sodium, potassium, calcium, and magnesium, or multilayer laminates are preferable. Among them, a metal selected from the group consisting of aluminum, silver, and magnesium is preferable in terms of resistance value, easiness of film formation, stability of film, and luminous efficiency. In particular, when the cathode contains magnesium and silver, electron injection into the electron transport layer and the electron injection layer is facilitated, and low voltage driving can be realized, which is preferable.

Further, preferred examples include metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium for protecting the cathode; alloys using the metals; cerium oxide, titanium oxide, and tantalum nitride. An inorganic compound such as an organic polymer compound such as polyvinyl alcohol, polyvinyl chloride or a hydrocarbon-based polymer compound is deposited as a protective film layer on the cathode. Further, a compound represented by the formula (1) can also be used as the protective film layer. However, in the case of an element structure (top emission structure) that derives light from the cathode side, the protective film layer is selected from materials having light transmissivity in the visible light region.

The electrodes are produced by resistance heating, electron beam, sputtering, ion plating, coating, and the like, and are not particularly limited.

The hole transport layer must efficiently transfer the holes injected from the anode between the electrodes to which the electric field is applied. Therefore, the hole transporting material is desirably high in hole injection efficiency and efficiently transports the injected holes. Therefore, the hole transporting material is required to have a suitable free potential, a large hole mobility, and excellent stability, and it is less likely to cause trapping impurities during production and use. The substance satisfying such conditions is not particularly limited, but is preferably 4,4'-bis(N-(3-methylphenyl)-N-anilino). Benzene, 4,4'-bis(N-(1-naphthyl)-N-anilino)biphenyl, 4,4',4"-tris(3-methylphenyl(phenyl)amino) a triphenylamine derivative such as phenylamine; a biscarbazole derivative such as bis(N-allylcarbazole) or bis(N-alkylcarbazole); a pyrazoline derivative; a stilbene compound; a fluorene compound; a benzofuran derivative or a thiophene derivative, an oxadiazole derivative, a phthalocyanine derivative, a porphyrin derivative or the like; a fullerene derivative; in the polymer system, preferably a polycarbonate or a styrene derivative having a monomer as described above in the side chain; or polythiophene, polyaniline, polyfluorene, polyvinylcarbazole, polydecane, or the like.

Further, as the hole transporting material, an inorganic compound such as p-type Si or p-type SiC can also be used. Further, a compound represented by the following formula (4), tetrafluorotetracyanoquinodimethane (4F-TCNQ) or molybdenum oxide can also be used.

R ²² ~ R ²⁷ may be same as each other or different, and are selected from the group consisting of halogen, sulfo acyl group, a carbonyl group, a nitro group, a cyano group and a trifluoromethyl group consisting of.

Wherein, if the hole transport layer or the hole injection layer contains the compound (5) (1, 4, 5, 8, 9, 12-hexaaza-linked triphenyl hexacarbonitrile), it becomes a lower voltage drive. Therefore, it is better.

The hole transport layer is formed by a method of laminating or mixing one or two or more types of hole transport materials, or a mixture of a hole transport material and a polymer binder. Further, an inorganic salt such as iron (III) chloride may be added to the hole transport material to form a hole transport layer.

The light emitting layer may be either a single layer or a multilayer. The luminescent material may be a mixture of the host material and the dopant material, or may be a single host material. That is, in the light-emitting layer, only the host material or the dopant material may emit light, or both the host material and the dopant material may emit light. From the viewpoint of efficiently utilizing electric energy and obtaining luminescence of high color purity, it is preferred that the luminescent layer contains a mixture of a host material and a dopant material. In addition, the host material and the dopant material may be one type or a combination of a plurality of types. The dopant material may be included in the entire host material or may be included in a portion of the host material. The dopant material may be laminated with a layer comprising the host material or may be dispersed in the host material. The luminescent color can be controlled by mixing the host material with the dopant material. In this case, if the amount of the dopant material is too large, concentration quenching occurs, so that the dopant material is preferably used in an amount of 20 wt% or less, more preferably 10 wt%, based on the host material. %the following. As a method of mixing the host material and the dopant material, the host material and the dopant material may be co-deposited, or the host material and the dopant material may be mixed in advance and then evaporated.

As the light-emitting material, specifically, a condensed ring derivative such as ruthenium or osmium; a metal chelate-based oxinoid compound including tris(8-hydroxyquinoline)aluminum; and a bisstyrylfluorene derivative may be used. a bisstyryl derivative such as a distyrylbenzene derivative; a tetraphenylbutadiene derivative, an anthracene derivative, a coumarin derivative, an oxadiazole derivative, a pyrrolopyridine derivative, a violet ring a ketone derivative, a cyclopentadiene derivative, an oxadiazole derivative, a thiadiazole pyridine derivative, a dibenzofuran derivative, a carbazole derivative, a carbazole derivative; in a polymer system, A polyphenylenevinyl derivative or a polyparaphenylene derivative can be used, and a polythiophene derivative or the like can be used, and it is not particularly limited.

The compound represented by the formula (1) also has high luminescent properties, and thus can be preferably used as a luminescent material. Since the compound represented by the formula (1) exhibits strong luminescence in the ultraviolet to blue region (300 nm to 450 nm region), it can be suitably used as a blue luminescent material. The compound represented by the formula (1) can also be used as a dopant material, but is excellent in film stability and is suitable as a host material. Further, since the compound represented by the general formula (1) has high luminous efficiency, high triplet energy level, bipolarity (two charge transport properties), and film stability, it is particularly preferably used as a combination with a phosphorescent dopant. The main material.

The host material need not be limited to only one compound, and a plurality of compounds may be mixed and used. The host material is not particularly limited, and naphthalene, anthracene, phenanthrene, anthracene, 1,2-benzophenanthrene, fused tetraphenyl, terphenyl, fluorene, fluoranthene, fluorene, a compound having a condensed aryl ring or a derivative thereof; an aromatic such as N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine a metal amine derivative; a metal chelate-based oxenyl compound such as tris(8-hydroxyquinoline)aluminum (III); a bisstyryl derivative such as a distyrylbenzene derivative; tetraphenylbutadiene Derivatives, anthracene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, benzalkonone derivatives, cyclopentadiene derivatives, pyrrolopyrrole derivatives, thiadiazolopyridine derivatives a dibenzofuran derivative, a carbazole derivative, a carbazole derivative, a triazine derivative; in the polymer system, a polyphenylenevinyl derivative, a polyparaphenylene derivative, a polyfluorene can be used. The derivative, the polyvinylcarbazole derivative, the polythiophene derivative, and the like are not particularly limited. Among them, as the host material used for the phosphorescence of the light-emitting layer, a metal chelate-based oxime compound, a dibenzofuran derivative, a carbazole derivative, a carbazole derivative, or a triazine derivative can be suitably used. Things and so on.

The dopant material is not particularly limited, and examples thereof include a compound having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, anthracene, 1,2-benzophenanthrene, a co-triphenyl, an anthracene, a fluoranthene, an anthracene or an anthracene. Or a derivative thereof (for example, 2-(benzothiazol-2-yl)-9,10-diphenylanthracene or 5,6,11,12-tetraphenyl fused tetraphenyl, etc.); furan, pyrrole, thiophene, Thiol, 9-fluorene, 9,9'-spirobifluorene, benzothiophene, benzofuran, anthracene, dibenzothiophene, dibenzofuran, imidazopyridine, morpholine, pyridine, pyrazine a compound having a heteroaryl ring or a derivative thereof, a naphthyridine, a quinoxaline, a pyrrolopyridine, a thioxanthene; a borane derivative; a distyrylbenzene derivative; 4,4'-bis(2-( Aminostyrene-based derivatives such as 4-diphenylaminophenyl)vinyl)biphenyl and 4,4'-bis(N-(stilbene-4-yl)-N-phenylamino)stilbene Aromatic acetylene derivative; tetraphenylbutadiene derivative; a stilbene derivative; an aldehyde nitrogen derivative; a pyrrolazole derivative; a diketopyrrolo[3,4-c]pyrrole derivative; 2,3,5,6-1H,4H-tetrahydro-9-( 2'-benzothiazolyl)quinazino[9,9a,1-gh]coumarin derivatives such as coumarin; imidazole, thiazole, thiadiazole, oxazole, oxazole, oxadiazole, triazole An oxazole derivative and a metal complex thereof; and N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diphenyl-1,1' An aromatic amine derivative represented by a diamine or the like.

Further, the dopant material used for the phosphorescence of the light-emitting layer preferably contains a material selected from the group consisting of iridium (Ir), ruthenium (Ru), palladium (Pd), platinum (Pt), osmium (Os), and ruthenium. (Re) a metal-missing compound of at least one metal in the group consisting of. The ligand is preferably a nitrogen-containing aromatic heterocyclic ring having a phenylpyridine skeleton or a phenylquinoline skeleton. However, it is not limited to these, and an appropriate complex compound can be selected according to the required luminescent color, element performance, and relationship with a host compound.

The electron transport layer refers to a layer that injects electrons from a cathode and further transports electrons. For the electron transport layer, electron injection efficiency is desired to be high, and the injected electrons are efficiently transmitted. Therefore, the electron transporting material is required to have a large electron affinity, a large electron mobility, and excellent stability, and it is difficult to generate impurities which are traps at the time of manufacture and use. In particular, when the film thickness is thick, the low molecular weight compound is crystallized or the like and the film quality is easily deteriorated. Therefore, in order to maintain a stable film quality, a compound having a molecular weight of 400 or more is preferable. On the other hand, when the transmission balance between the hole and the electron is considered, if the electron transport layer functions to efficiently prevent the hole from the anode from recombining and flow to the cathode side, even if the electron transport layer contains electron transport capability Not so high material, improve luminous efficiency It is also the same as the case of materials containing high electron transport capability.

The electron transporting material need not be limited to one type, and a plurality of compounds may be mixed and used. The electron transporting material is not particularly limited, and examples thereof include a compound having a condensed aryl ring such as naphthalene, anthracene, and an anthracene or a derivative thereof; and 4,4′-bis(diphenylvinyl)biphenyl is represented. a styrene-based aromatic ring derivative; an anthracene derivative; a purple ring ketone derivative; a coumarin derivative; a naphthoquinone imine derivative; an anthracene derivative such as hydrazine or biphenyl hydrazine; A carbazole derivative; an anthracene derivative; a hydroxyquinoline complex such as tris(8-hydroxyquinoline)aluminum (III); a hydroxyzole complex such as a hydroxyphenyl oxazole complex; a cycloheptamolone metal complex; and a flavonol metal complex.

The compound represented by the general formula (1) is particularly suitable as an electron transporting material because of its high electron injecting and transporting ability. Further, when the electron transport layer further contains a donor compound, it has high compatibility with the donor compound in a thin film state, and exhibits higher electron injecting and transporting ability. By the action of the mixture layer, the transmission of electrons from the cathode toward the light-emitting layer is promoted, and the effects of high luminous efficiency and low driving voltage are further enhanced.

The donor compound is a compound which facilitates electron injection from the cathode or the electron injection layer toward the electron transport layer by improving the electron injection barrier, thereby improving the conductivity of the electron transport layer. In other words, in the light-emitting element of the present invention, in addition to the compound represented by the formula (1), the electron-transporting layer preferably contains a donor compound in order to enhance electron transporting ability.

Preferable 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 compound, an alkaline earth metal, an inorganic salt containing an alkaline earth metal, or a mixture of an alkaline earth metal and an organic substance. Object Wait. Preferred examples of the alkali metal and the alkaline earth metal include an alkali metal such as lithium, sodium or barium having a low work function and an effect of improving electron transporting ability, or an alkaline earth metal such as magnesium or calcium.

In addition, in the case where the vapor deposition in a vacuum is easy and the handleability is excellent, the donor compound is preferably an inorganic salt or a complex of a metal and an organic compound as compared with the metal monomer. Further, from the viewpoint of easiness of treatment in the atmosphere or easy control of the concentration of addition, it is more preferably in a state of a complex of a metal and an organic substance. Examples of the inorganic salt 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 , and Rb ₂ CO ₃ . Carbonate such as Cs ₂ CO ₃ or the like. Further, as a preferred example of the alkali metal or the alkaline earth metal, lithium is exemplified as being inexpensive and easy to synthesize. Further, preferred examples of the organic substance in the complex of the metal and the organic compound include hydroxyquinoline, benzoquinolinol, flavonol, hydroxyimidazopyridine, hydroxybenzoxazole, and hydroxytriazole. Among them, a complex of an alkali metal and an organic compound is preferred, and a complex of lithium and an organic compound is more preferred, and lithium quinolate is particularly preferred.

Further, if the doping ratio of the donor compound in the electron transport layer is appropriate, the injection ratio of electrons from the cathode or the electron injection layer toward the electron transport layer is increased, between the cathode and the electron injection layer, or the electron injection layer and the electron The energy barrier between the transmission layers is alleviated, and low drive voltage is achieved. The appropriate doping concentration varies depending on the thickness of the material or the doped region, but it is preferably such that the ratio of the vapor deposition rate of the electron transporting material to the donor compound is in the range of 100:1 to 1:100. Evaporation to form an electron transport layer. The evaporation rate ratio is preferably 10:1 to 1:10, and particularly preferably 7:3 to 3:7.

The method of doping the electron-transporting layer with a donor compound to enhance the electron transporting ability particularly exerts an effect when the film thickness of the organic layer is thick. When the total thickness of the electron transport layer and the light-emitting layer is 50 nm or more, the effect is particularly large. For example, there is a method of utilizing an interference effect for improving luminous efficiency, which is a method of integrating the phase of light directly emitted from the light-emitting layer with the phase of light reflected by the cathode to improve light extraction efficiency. The optimum condition is that the light emission wavelength of the light changes, but the total thickness of the electron transport layer and the light-emitting layer becomes 50 nm or more. In addition, when the light emission is long-wavelength light emission such as red, there is a case where the total thickness of the electron transport layer and the light-emitting layer becomes a thick film close to 100 nm.

When the donor compound is doped, it is preferred that the thicker the film thickness of the entire electron transport layer, the more concentrated the doping concentration. When doping may be part of the electron transport layer, or the entire electron transport layer, when doping a portion of the electron transport layer, it is desirable to provide a doped region at least at the electron transport layer/cathode interface, The reason is that a low voltage effect can be obtained. Further, when the donor compound is doped into the light-emitting layer, the effect of lowering the light-emitting efficiency is adversely affected. It is preferable to provide an undoped region at the interface of the light-emitting layer/electron transport layer.

The method of forming the respective layers constituting the light-emitting element is, for example, resistance heating deposition, electron beam evaporation, sputtering, molecular layering, coating, or the like, and is not particularly limited. However, from the viewpoint of device characteristics, resistance is preferred. Heating evaporation or electron beam evaporation.

The thickness of the entire organic layer is also dependent on the resistance value of the luminescent material, and therefore cannot be limited, but is preferably 1 nm to 1000 nm. Light-emitting layer, electron The film thickness of the transport layer and the hole transport layer is preferably 1 nm or more and 200 nm or less, and more preferably 5 nm or more and 100 nm or less.

The light emitting element has a function of converting electric 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 the voltage value are not particularly limited, but in consideration of the power consumption or life of the element, it should be selected in such a manner that the maximum brightness is obtained with the lowest possible energy.

The light-emitting element of the present invention is suitable for use as, for example, a matrix type and/or a segment type display.

The matrix method refers to a method in which pixels for display are two-dimensionally arranged in a lattice shape or a mosaic shape, and characters or images are displayed by a collection of pixels. The shape or size of the pixels is determined according to the purpose. For example, in the image and text display of a personal computer, a monitor, and a television, a quadrilateral pixel having a side of 300 μm or less is used, and in the case of a large display such as a display panel, the use side is mm-level. Picture. In the case of monochrome display, pixels of the same color may be arranged, but in the case of color display, pixels of red, green, and blue are displayed in parallel. In this case, the arrangement of typical pixels is triangular and striped. In addition, the driving method of the matrix may be any of a line sequential driving and an active matrix. In the case of line sequential driving, the structure of the display is simple, but the active matrix is superior in terms of operational characteristics, and therefore must be used depending on the application.

The segment method refers to a method of forming a pattern in such a manner as to display information determined in advance, and determining the pattern by the arrangement of the pattern. The area glows. Examples of the segment type display include a time or temperature display in a digital clock or a thermometer, an operation state display such as an audio device or an induction cooker, and a panel display of a car. The above matrix display and segment display can also coexist in the same panel.

The light-emitting element of the present invention can also be preferably used as a backlight for various machines and the like. The backlight is mainly used for 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 logo, and the like. In particular, the light-emitting element of the present invention can be preferably used in a liquid crystal display device, and the thinning is being used as a backlight for researching personal computers, and can provide a thinner and lighter backlight than the previous backlight.

[Example]

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited by the examples.

Synthesis Example 1

Synthesis of Compound [1]

Under a nitrogen gas stream, 68 mL of sulfuric acid was slowly added to a solution containing 25.0 g of 2-bromoindole, 12.2 g of iodine, and 680 ml of acetic acid. After slowly adding 7.1 g of sodium nitrite to the mixed solution, the mixture was stirred under reflux for 2 hours. After cooling the reaction mixture to room temperature, the precipitate was filtered. The obtained precipitate was washed with ethyl acetate, water and methanol, respectively, and then subjected to vacuum drying, whereby 25.9 g of 2-bromo-7-iodonium (yield: 68%) was obtained.

Then, a solution of 19.6 g of potassium third butoxide and 317 mL of dimethyl hydrazine was cooled to 0 ° C under a nitrogen stream, and then 2-bromo-7-iodonium was added. 25.9g. Further, 29.7 g of methyl iodide was slowly added, and the reaction mixture was stirred at room temperature for 4 hours. 317 mL of water was added to the reaction mixture, and the precipitate was filtered. The precipitate was dissolved in toluene, dried with magnesium sulfate, filtered through a ceria pad, and then the filtrate was evaporated. 50 ml of methanol was added to the obtained solid, and it was filtered. Further, the solid was redissolved in toluene, filtered through a ceria pad, and then the filtrate was evaporated. The precipitate was filtered and dried under vacuum, whereby 2-bromo-7-iodo-9,9-dimethylindole 21.5 g (yield: 77%) was obtained.

Then, 10.0 g of 2-bromo-7-iodo-9,9-dimethylhydrazine, 7.9 g of 3-(9-oxazolyl)phenylboronic acid, 125 mL of dimethoxyethane and 1.5 M aqueous sodium carbonate solution After 37 mL of the mixed solution was purged with nitrogen, 176 mg of bis(triphenylphosphine)palladium dichloride was added, and the mixture was stirred under heating at 60 ° C for 6 hours. After cooling the reaction mixture to room temperature, extraction was carried out with 200 ml of toluene. The obtained organic layer was washed three times with 100 ml of water, dried with sodium sulfate, and then filtered. The filtrate was evaporated and purified by cartridge chromatography, and then the eluate was evaporated. 50 ml of methanol was added to the obtained solid, and the mixture was filtered, followed by vacuum drying, whereby 10.5 g of an intermediate (A) was obtained (yield: 81%).

Then, the intermediate (A) 6.0g, 4-chlorophenylboronic acid 2.0g, two After a mixed solution of 58 mL of methoxyethane and 17 mL of a 1.5 M sodium carbonate aqueous solution was replaced with nitrogen, 82 mg of bis(triphenylphosphine)palladium dichloride was added, and the mixture was heated and stirred under reflux for 6 and a half hours. After cooling the reaction mixture to room temperature, extraction was carried out using 750 mL of toluene. The obtained organic layer was washed three times with 100 ml of water, dried with sodium sulfate, and then filtered. The filtrate was evaporated and purified by cartridge chromatography, and then the eluate was evaporated. 20 ml of methanol was added to the obtained solid, and the mixture was filtered, followed by vacuum drying, whereby 5.7 g of an intermediate (B) was obtained (yield: 89%).

Then, the intermediate (B) 3.0g, 3-pyridine boronic acid 0.74g, bis (dibenzylideneacetone) palladium 36mg, tricyclohexylphosphine. A mixed solution of 49 mg of tetrafluoroborate and 28 ml of 1,4-dioxane was replaced with nitrogen, and then 7.4 ml of a 1.27 M aqueous solution of tripotassium phosphate was added, followed by heating under reflux for 7 hours under a nitrogen stream. After cooling the reaction mixture to room temperature, 28 ml of water was added, and the precipitate was filtered, and then dried by a vacuum dryer. The precipitate was purified by ruthenium column chromatography, and then the eluate was evaporated. To the obtained solid, 20 ml of methanol was added and filtered. After vacuum drying the solid, 65 mL of o-xylene was used and refined by recrystallization. The system thus obtained 2.2 g of white crystals (yield: 67%).

The result of ¹ H-NMR analysis of the obtained white crystal was as follows, and it was confirmed that the white crystal obtained above was the compound [1].

Compound [1]: ¹ H-NMR (CDCl ₃ (d=ppm)) δ 1.60 (s, 6H), 7.29 (td, 2H), 7.37-7.58 (m, 6H), 7.63-7.78 (m, 7H) , 7.81-7.89 (m, 6H), 7.94 (dt, 1H), 8.18 (d, 2H), 8.62 (dd, 1H), 8.93 (d, 1H).

Further, the compound [1] was sublimed and purified at about 310 ° C using an oil diffusion pump under a pressure of 1 × 10 ^-3 Pa, and used as a light-emitting device material. The purity of High Performance Liquid Chromatography (HPLC) (area % at a measurement wavelength of 254 nm) was 99.7% before sublimation purification, and 99.7% after sublimation purification.

Synthesis Example 2

Synthesis of Compound [2]

A mixed solution of 2.4 g of the intermediate (A), 2.1 g of 4-(4-pyridyl)phenylboronic acid pinacol ester, 24 mL of dimethoxyethane, and 7 mL of a 1.5 M sodium carbonate aqueous solution was added, followed by nitrogen substitution. 33 mg of bis(triphenylphosphine)palladium dichloride was stirred and heated under reflux for 12 and a half hours. After cooling the reaction mixture to room temperature, 24 mL of water was added, and then the precipitate was filtered and vacuum was applied. dry. The precipitate was purified by a silica gel column chromatography, and 0.5 g of QuadraSil (registered trademark) as a scavenger was added to the eluate, and the mixture was stirred at room temperature for 1 hour, and then filtered using a ceria pad, followed by distillation. Remove the solvent. Recrystallization of the obtained solid was carried out using 73 mL of o-xylene to obtain white crystals (yield: 73%).

The result of ¹ H-NMR analysis of the obtained white crystal was as follows, and it was confirmed that the white crystal obtained above was the compound [2].

Compound [2]: ¹ H-NMR (CDCl ₃ (d=ppm)) δ 1.60 (s, 6H), 7.31 (td, 2H), 7.41-7.52 (m, 4H), 7.55-7.59 (m, 3H) , 7.64 - 7.89 (m, 13H), 8.18 (d, 2H), 8.69 (dd, 2H).

Further, the compound [2] was sublimed and purified at about 310 ° C using an oil diffusion pump under a pressure of 1 × 10 ^-3 Pa, and used as a light-emitting device material. The HPLC purity (area % at a measurement wavelength of 254 nm) was 99.9% before sublimation purification, and 99.9% after sublimation purification.

Synthesis Example 3

Synthesis of Compound [3]

11.5 g of 2-bromo-7-iodo-9,9-dimethylhydrazine, 9.1 g of 4-(9-oxazolyl)phenylboronic acid, 144 mL of dimethoxyethane and 1.5 M sodium carbonate aqueous solution 42 After the mixed solution of mL was purged with nitrogen, 202 mg of bis(triphenylphosphine)palladium dichloride was added, and the mixture was stirred under heating at 60 ° C for 5.5 hours. After cooling the reaction mixture to about 40 ° C, 200 mL of water was added, and the precipitate was filtered. The precipitate was washed with methanol, then filtered, and vacuum dried. The precipitate was purified by ruthenium column chromatography, and then the eluate was evaporated. To the obtained solid, 100 ml of methanol was added, followed by filtration, and vacuum drying was performed, whereby 10.1 g (yield 68%) of the intermediate (C) was obtained.

A mixed solution of 5.1 g of an intermediate (C), 3.5 g of 4-(3-pyridyl)phenylboronic acid pinacol ester, 49 mL of dimethoxyethane, and 14 mL of a 1.5 M sodium carbonate aqueous solution was added, followed by nitrogen substitution. 138 mg of bis(triphenylphosphine)palladium dichloride was then stirred and heated under reflux for 7 and a half hours. After cooling the reaction mixture to room temperature, the precipitate was filtered and dried under vacuum. The precipitate was dissolved in 500 mL of tetrahydrofuran (THF), and 0.5 g of activated carbon and 0.8 g of QuadraSil (registered trademark) were added thereto, and the mixture was stirred at room temperature for 1 hour, and then filtered through a ceria pad. The eluate was evaporated. To the obtained solid, 20 ml of methanol was added and filtered. After vacuum drying the solid, 120 mL of N,N-dimethylformamide was used for further crystallization. Further, 105 mL of N,N-dimethylformamide was used for recrystallization, whereby 4.3 g of pale yellow crystals (yield: 75%) was obtained.

The result of ¹ H-NMR analysis of the obtained pale yellow crystal was as follows, and it was confirmed that the pale yellow crystal obtained above was the compound [3].

Compound [3]: ¹ H-NMR (CDCl ₃ (d=ppm)) δ 1.65 (s, 6H), 7.30 (td, 2H), 7.38-7.52 (m, 5H), 7.64-7.98 (m, 15H) , 8.18 (d, 2H), 8.63 (dd, 1H), 8.94 (d, 1H).

Further, the compound [3] was subjected to sublimation purification at a pressure of 1 × 10 ^-3 Pa at about 320 ° C using an oil diffusion pump, and then used as a light-emitting device material. The HPLC purity (area % at a measurement wavelength of 254 nm) was 99.9% before sublimation purification, and 99.9% after sublimation purification.

Synthesis Example 4

Synthesis of Compound [4]

A mixed solution of 5.1 g of the intermediate (C), 2.2 g of 4-(2-pyridyl)phenylboronic acid, 49 mL of dimethoxyethane, and 14 mL of a 1.5 M sodium carbonate aqueous solution was replaced with nitrogen, and then bis(triphenyl) was added. 69 mg of palladium dichloride, followed by heating and stirring under reflux for 4 and a half hours. After cooling the reaction mixture to room temperature, 49 mL of water was added, and the precipitate was filtered and dried under vacuum. The precipitate was purified by a silica gel column chromatography, and 0.8 g of QuadraSil (registered trademark) was added to the eluate, and the mixture was stirred at room temperature for 1 hour, and then filtered through celite. After evaporating the filtrate, 20 ml of methanol was added to the obtained solid, and the mixture was filtered. The filtrate was vacuum dried, and then recrystallized using 54 mL of N,N-dimethylformamide. Further, 46 mL of N,N-dimethylformamide was used for recrystallization, whereby 3.5 g of a white crystal was obtained (yield: 60%).

The result of ¹ H-NMR analysis of the obtained white crystal was as follows, and it was confirmed that the white crystal obtained above was the compound [4].

Compound [4]: ¹ H-NMR (CDCl ₃ (d=ppm)) δ 1.65 (s, 6H), 7.31 (td, 2H), 7.41-7.52 (m, 4H), 7.66-7.93 (m, 15H) , 8.12-8.19 (m, 4H), 8.74 (dt, 1H).

Further, the compound [4] was sublimed and purified at about 320 ° C using an oil diffusion pump under a pressure of 1 × 10 ^-3 Pa, and used as a light-emitting device material. The HPLC purity (area % at a measurement wavelength of 254 nm) was 99.8% before sublimation purification, and was 99.8% after sublimation purification.

Example 1

A glass substrate (manufactured by Geomatec Co., Ltd., surface resistance: 11 Ω/□, sputtered product) having an ITO transparent conductive film deposited at 150 nm was cut into 38 mm × 46 mm, and then etched to form an ITO transparent conductive film. The specified electrode shape. The obtained substrate was subjected to ultrasonic cleaning for 15 minutes using "Semico Clean 56" (trade name, manufactured by Furuuchi Chemical Co., Ltd.), and then washed with ultrapure water. The substrate was subjected to ultraviolet (Ultraviolet, UV)-ozone treatment for 1 hour immediately before the device was fabricated, and then placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ^-4 Pa or less. . On the ITO transparent conductive film, a 10 nm thick copper phthalocyanine was first deposited by a resistance heating method as a hole injection layer, and a 50 nm thick 4,4'-bis(N-(1-naphthyl)--evaporated layer was deposited. N-anilinobiphenyl is used as a hole transport layer. Then, a layer in which a compound (H-1) as a host material and a compound (D-1) as a dopant material are mixed, and a thickness of 40 nm is deposited as a light-emitting layer so that the dopant concentration is 5 wt%. . Then, a layer in which the compound [1] and lithium fluoride as a donor compound are mixed is deposited at a vapor deposition rate ratio of 1:1 (=0.05 nm/s: 0.05 nm/s) to a thickness of 20 nm. The layer is used as an electron transport layer.

Then, lithium fluoride was vapor-deposited to a thickness of 0.5 nm, and then aluminum was vapor-deposited to a thickness of 1000 nm to serve as a cathode, thereby producing a light-emitting element having a light-emitting surface of 5 mm × 5 mm square. The film thickness described here is a display value of a quartz oscillation type film thickness monitor. The light-emitting element was driven by DC at 10 mA/cm ² , and as a result, high-efficiency blue light emission having a driving voltage of 4.7 V and an external quantum efficiency of 5.4% was obtained.

[化35]

Example 2 ~ Example 27

A light-emitting device was produced in the same manner as in Example 1 except that the materials described in Tables 1 and 2 were used as the host material, the dopant material, and the electron transport layer. The results are shown in Tables 1 and 2. Further, the compound [5] to the compound [19] and 2E-1 are the compounds shown below.

[化36]

Comparative Example 1 to Comparative Example 12

A light-emitting element was produced in the same manner as in Example 1 except that the material described in Table 2 was used as the host material, the dopant material, and the electron transport layer. The results are shown in Table 2. Furthermore, in Tables 1 and 2, the compounds E-1, compound E-2, compound E-3, and compound E-4 are the compounds shown below.

[化37]

Example 28 to Example 38

A light-emitting element was produced in the same manner as in Example 1 except that the material described in Table 3 was used as the host material, the dopant material, and the electron transport layer. The evaluation results are shown in Table 3. Further, in Table 3, the compound H-2 to the compound H-8 and the compound D-2 to the compound D-10 are the compounds shown below.

[化38]

[39]

Example 39 to Example 46, Comparative Example 13 to Comparative Example 20

A light-emitting element was fabricated in the same manner as in Example 1 except that the material described in Table 4 was used as the host material and the dopant material, and tris(8-hydroxyquinoline)aluminum (Alq) was used as the electron transport layer. . The evaluation results are shown in Table 4.

[Industrial availability]

The present invention provides a light-emitting element material which can realize an organic thin film light-emitting element which has high light-emitting efficiency and a low driving voltage, and a light-emitting element using the same. The light-emitting element material of the present invention can be preferably used for an electron transport layer or a light-emitting layer of a light-emitting element.

Claims (12)

A light-emitting element material comprising a compound represented by the following formula (1): In the formula, Y is a group represented by the following formula (2); Ar ¹ is a group represented by the following formula (3); L ¹ is a single bond or is selected from a nucleus carbon number of 5 to 12 a substituted or unsubstituted extended aryl group, and a substituted or unsubstituted heteroaryl group; L ² is a substituted or unsubstituted aryl group having a nucleus number of 5 to 12 a group in the substituted or unsubstituted heteroaryl group; Ar ² is a group containing only an aromatic heterocyclic group containing an electron-accepting nitrogen which is unsubstituted or substituted with an alkyl group or a cycloalkyl group; n is an integer of 1 to 5; n Ar ² may be the same or different; wherein at least one of L ¹ and L ² is a substituted or unsubstituted extended aryl group having a core number of 5 to 12; R ¹ to R ¹⁰ may be the same as or different from each other and are selected from the group consisting of hydrogen, alkyl, cycloalkyl, heterocyclic, alkenyl, cycloalkenyl, alkynyl, alkoxy, alkylthio, aryl ether. the group consisting of R ¹¹ R ¹² in the group, aryl thioether group, aryl, heteroaryl, halo, carbonyl, carboxyl, oxycarbonyl group, carbamoyl acyl and -P (= O); R ¹¹ And R ¹² is a group selected from the group consisting of an aryl group and a heteroaryl group; R ¹ to R ⁸ and R ¹¹ to R ¹² may form a ring by a contiguous substituent; R ⁹ and R ¹⁰ are an alkyl group or a cycloalkane. a group, an aryl group or a heteroaryl group; wherein any one of R ¹ to R ⁸ is for linking to L ¹ , and further, any of the others is for linking to L ² ; R ¹³ to R ²¹ may be the same or different from each other, and are a group selected from the group consisting of hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an aryl group and a heteroaryl group; R ¹³ to R ²¹ The ring may be formed by adjacent substituents; wherein any one of R ¹³ to R ²¹ is used for the linkage with L ¹ . The light-emitting device material according to claim 1, wherein the aromatic heterocyclic group containing an electron-accepting nitrogen is selected from the group consisting of pyridyl, quinolyl, isoquinolyl, quinoxalinyl, pyrazinyl, pyrimidine. a group consisting of pyridyl, pyridazine, morpholinyl, imidazopyridyl, triazinyl, acridinyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, bipyridyl and terpyridine group. The light-emitting device material according to claim 1 or 2, wherein Ar ^{2 is} selected from the group consisting of the groups shown below; Among them, these groups may also be substituted by an alkyl group or a cycloalkyl group. The light-emitting device material according to claim 1 or 2, wherein R ⁷ in the formula (2) is used for linking to L ¹ . The light-emitting device material according to claim 1 or 2, wherein R ² in the formula (2) is used for linking to L ² . The light-emitting device material according to claim 1 or 2, wherein R ¹⁵ , R ¹⁸ or R ²¹ in the formula (3) is used for linking with L ¹ . A light-emitting element which is an organic layer between an anode and a cathode and emits light by electric energy, wherein in the organic layer The light-emitting device material according to any one of claims 1 to 6. The light-emitting element according to claim 7, wherein the organic layer comprises an electron-transporting layer, and the electron-transporting layer contains the light-emitting element material according to any one of the first to sixth aspects of the invention. The light-emitting element according to claim 8, wherein the electron transport layer further contains a donor compound. The light-emitting element according to claim 9, wherein the donor compound is an alkali metal, an alkali metal-containing inorganic salt, an alkali metal-organic complex, an alkaline earth metal, an alkaline earth metal-containing inorganic salt, or A complex of an alkaline earth metal with an organic matter. The light-emitting element according to claim 10, wherein the donor compound is a complex of an alkali metal and an organic substance, or a complex of an alkaline earth metal and an organic substance. The light-emitting element according to claim 7, wherein the organic layer comprises a light-emitting layer, and the light-emitting layer contains the light-emitting element material according to any one of the first to sixth aspects of the invention.