WO2012157537A1 - Light-emitting element material and light-emitting element - Google Patents

Abstract

Provided are: a light-emitting element material which contains a specific compound having a fluorene skeleton, a carbazole group and an aromatic heterocyclic group containing an electron-accepting nitrogen and which is capable of providing an organic thin film light-emitting element that has a good balance between high luminous efficiency and low driving voltage; and a light-emitting element which uses the light-emitting element material.

Description

Light emitting device material and light emitting device

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

In recent years, research on organic thin-film light emitting devices that emit light when electrons injected from a cathode and holes injected from an anode are recombined in an organic phosphor sandwiched between both electrodes has been actively conducted. This light-emitting element is characterized by being thin and capable of high-intensity light emission under a low driving voltage and multicolor light emission by selecting a fluorescent material. Kodak's C.I. W. Since Tang et al. Have shown that organic thin film light emitting devices emit light with high brightness, many research institutions have been studying organic thin film light emitting devices.

Also, organic thin-film light-emitting elements can be obtained in various light-emitting colors by using various fluorescent materials for the light-emitting layer, and therefore, research for practical application to displays and the like is active. 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.

Organic thin-film light-emitting elements need to improve luminous efficiency, drive voltage, and durability. In particular, when the luminous efficiency is low, it is impossible to output an image that requires high luminance, and the amount of power consumption for outputting desired luminance increases. For example, in order to improve luminous efficiency, various luminescent materials and electron transport materials having fluorene as a basic skeleton have been developed (see Patent Documents 1 to 4).

JP 2004-91350 A JP 2010-215759 A JP 2004-277377 A JP 2008-208065 A

However, the conventionally known materials have not been compatible with low voltage driving and high luminous efficiency. SUMMARY OF THE INVENTION It is an object of the present invention to provide a light emitting device material that solves the problems of the prior art and enables an organic thin film light emitting device having both high luminous efficiency and low driving voltage, and a light emitting device using the same. It is.

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

In the formula, Y is a group represented by the following general formula (2); Ar ¹ is a group represented by the following general formula (3); L ¹ is a single bond or a substituted or unsubstituted group having 5 to 12 nuclear carbon atoms. A group selected from an arylene group and a substituted or unsubstituted heteroarylene group; L ² is a group selected from a substituted or unsubstituted arylene group having 5 to 12 nuclear carbon atoms and a substituted or unsubstituted heteroarylene group; Ar also the n Ar ² is the same; ^2, aromatic heterocyclic group only consists group containing electron-accepting nitrogen, which is unsubstituted or substituted alkyl group or a cycloalkyl group; n is an integer from 1 to 5 May be different.

R ¹ to R ¹⁰ may be the same or different and each represents hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether A group 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 and —P (═O) R ¹¹ R ¹² ; R ¹¹ and R ¹² are aryl groups R ¹ to R ¹² may form a ring with adjacent substituents; provided that any one of R ¹ to R ⁸ is a group selected from L ¹ and a heteroaryl group; used in connection, one further one of the other is used for connection with the L ^2.

R ¹³ to R ²¹ may be the same or different and each is 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 with adjacent substituents. However, any one of R ¹³ to R ²¹ is used for connection with L ¹ .

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

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

In the formula, Y is a group represented by the following general formula (2), and Ar ¹ is a group represented by the following general formula (3). L ¹ is a single bond or a group selected from a substituted or unsubstituted arylene group having 5 to 12 nuclear carbon atoms and a substituted or unsubstituted heteroarylene group. L ² is a group selected from a substituted or unsubstituted arylene group having 5 to 12 nuclear carbon atoms and a substituted or unsubstituted heteroarylene group. Ar ² is a group composed only of 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.

R ¹ to R ¹⁰ may be the same or different and each represents hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether A group 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, and —P (═O) R ¹¹ R ¹² . R ¹¹ and R ¹² are groups selected from aryl groups and heteroaryl groups. R ¹ to R ¹² may form a ring with adjacent substituents. However, any one of R ¹ to R ⁸ is used for connection with L ^1, and any other one is used for connection with L ² . Here, any one of R ¹ to R ⁸ is used for linking with L ¹ means that the group represented by the general formula (2) is located at any one position of R ¹ to R ^8. This means that it is directly bonded to L ¹ . The same is true for L ^2.

R ¹³ to R ²¹ may be the same or different and each is 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 with adjacent substituents. However, any one of R ¹³ to R ²¹ is used for connection with L ¹ . Here, any one of R ¹³ to R ²¹ is used for linking to L ¹ means that the group represented by the general formula (3) is located at any one position of R ¹³ to R ^21. This means that it is directly bonded to L ¹ .

In all the above groups, 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 preferably 1 or more and 20 or less, more preferably 1 or more and 8 or less, from the viewpoint of availability and cost.

The cycloalkyl group refers to, for example, a saturated alicyclic hydrocarbon group such as a cyclopropyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, which may or may not have a substituent. The number of carbon atoms in the alkyl group moiety is not particularly limited, but is preferably in the range of 3 or more and 20 or less.

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, Preferably it is the range of 2-20.

An alkenyl group refers to an unsaturated aliphatic hydrocarbon group containing a double bond such as a vinyl group, an allyl group, or a butadienyl group, which may or may not have a substituent. Although carbon number of an alkenyl group is not specifically limited, Preferably 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.

The alkynyl group indicates, for example, an unsaturated aliphatic hydrocarbon group containing a triple bond such as an ethynyl group, which may or may not have a substituent. The number of carbon atoms 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 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, Preferably 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, Preferably 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, Preferably, it is the range of 6-40.

The aryl thioether group is a group in which an oxygen atom of an ether bond of an 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, Preferably, it is the range of 6-40.

The aryl group represents, 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 pyrenyl group. The aryl group may or may not have a substituent. Although carbon number of an aryl group is not specifically limited, Preferably, it is the range of 6-40.

A heteroaryl group is a furanyl group, thiophenyl group, pyridyl group, quinolinyl group, isoquinolinyl group, pyrazinyl group, pyrimidyl group, naphthyridyl group, benzofuranyl group, benzothiophenyl group, indolyl group, dibenzofuranyl group, dibenzothiophenyl group And a cyclic aromatic group having one or more atoms other than carbon in the ring, such as a carbazolyl group, which may be unsubstituted or substituted. Although carbon number of heteroaryl group is not specifically limited, Preferably it is the range of 2-30.

Halogen refers to an atom selected from fluorine, chlorine, bromine and iodine.

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

An arylene group refers to a divalent group derived from an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, or a biphenyl group, which may or may not have a substituent. When L ¹ or L ^{2 in} the general formula (1) is an arylene group, the number of nuclear carbon atoms is preferably in the range of 5 or more and 12 or less. Specific examples of the arylene group include 1,4-phenylene group, 1,3-phenylene group, 1,2-phenylene group, 4,4′-biphenylylene group, 4,3′-biphenylylene group, 3,3 Examples include '-biphenylylene group, 1,4-naphthylene group, 1,5-naphthylene group, 2,5-naphthylene group, 2,6-naphthylene group, 2,7-naphthylene group and the like. More preferred is a 1,4-phenylene group.

When adjacent substituents form a ring, any adjacent two substituents (for example, R ² and R ^{3 in} formula (2)) 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, an atom selected from nitrogen, oxygen, sulfur, phosphorus and silicon may be contained, or it may be condensed with another ring.

A heteroarylene group is derived from an aromatic group having one or more atoms other than carbon in the ring, such as a pyridyl group, a quinolinyl group, a pyrazinyl group, a naphthyridyl group, a dibenzofuranyl group, a dibenzothiophenyl group, or a carbazolyl group. A divalent group to be removed, which may or may not have a substituent. The number of carbon atoms of the heteroarylene group is not particularly limited, but is preferably in the range of 2-30.

The aromatic heterocyclic group containing electron-accepting nitrogen refers to a cyclic aromatic group having one or more electron-accepting nitrogen atoms in the ring as atoms other than carbon in the heteroaryl group. Although the number of electron-accepting nitrogen contained in the aromatic heterocyclic group containing electron-accepting nitrogen is not particularly limited, it is preferably in the range of 1 or more and 6 or less. In addition, these may be substituted with an alkyl group or a cycloalkyl group.

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

Examples of aromatic heterocyclic groups containing electron-accepting nitrogen include pyridyl group, quinolinyl group, isoquinolinyl group, quinoxanyl group, pyrazinyl group, pyrimidyl group, pyridazinyl group, phenanthrolinyl group, imidazopyridyl group, triazyl group, Examples include an acridyl group, a benzimidazolyl group, a benzoxazolyl group, a benzothiazolyl group, a bipyridyl group, and a terpyridyl group. Although carbon number of the aromatic heterocyclic group containing electron-accepting nitrogen is not specifically limited, Preferably it is the range of 2-30. The connecting position of the aromatic heterocyclic group containing an electron-accepting nitrogen may be any part. For example, in the case of a pyridyl group, any of 2-pyridyl group, 3-pyridyl group and 4-pyridyl group may be used.

In the compound represented by the general formula (1), Ar ² is a group composed of only an aromatic heterocyclic group containing an electron-accepting nitrogen which is unsubstituted or substituted with an alkyl group or a cycloalkyl group. An aromatic heterocyclic group containing electron-accepting nitrogen is present on the outside (end) of the molecule. Accordingly, when the compound represented by the general formula (1) is used for the electron transport layer, it becomes easier to receive electrons from the cathode, and the driving voltage of the light emitting element can be lowered. In addition, since the electron donation to the light emitting layer is increased and the probability of recombination of electrons and holes is increased, the light emission efficiency of the light emitting element is improved.

Incidentally, Ar ² is and a group composed of only aromatic heterocyclic group containing electron-accepting nitrogen, which is unsubstituted or substituted alkyl group or a cycloalkyl group, Ar ² is an unsubstituted aromatic heterocyclic Of course, when it is a cyclic group, Ar ² is an aromatic heterocyclic group substituted, and the substituent includes an aromatic heterocyclic group containing an alkyl group, a cycloalkyl group, and an electron-accepting nitrogen. The case where it is selected from a cyclic group is also included. Examples of the latter include a bipyridyl group and a bis (pyridyl) pyridyl group (both are pyridyl groups having a pyridyl group which is an aromatic heterocyclic group containing an electron-accepting nitrogen as a substituent). Note that a group composed only of an aromatic heterocyclic group containing an electron-accepting nitrogen may be substituted with an alkyl group or a cycloalkyl group, but is not substituted with an aromatic group containing no electron-accepting nitrogen. must not. When the substituent is an alkyl group or a cycloalkyl group, conjugation does not extend to these groups, and thus the electron affinity of the aromatic heterocyclic ring containing electron-accepting nitrogen is not greatly affected. On the other hand, when an aromatic heterocyclic group containing an electron-accepting nitrogen is substituted with an aromatic group that does not contain an electron-accepting nitrogen such as an aryl group, conjugation extends to these substituents, resulting in an electron accepting property. The high electron affinity of the aromatic heterocycle containing nitrogen is impaired. That is, even if a group composed only of an aromatic heterocyclic group containing an electron-accepting nitrogen is substituted with an alkyl group or a cycloalkyl group, the above effect is not impaired, but an aromatic containing no electron-accepting nitrogen is used. When substituted with a group, the above effect is impaired.

More specifically, Ar ² is preferably selected from the group consisting of the following groups.

In the above, the solid line indicating the bonding position between Ar ² and L ² is drawn through the ring constituting each multi-membered ring. This is because the bonding position between Ar ² and L ² is Ar It means that it may be at any position of the ² multi-membered ring. For example, a pyridyl group represents any of 2-pyridyl group, 3-pyridyl group and 4-pyridyl group, and quinolyl group represents 2-quinolinyl group, 3-quinolinyl group, 4- It represents that any of a quinolinyl group, a 5-quinolinyl group, a 6-quinolinyl group, a 7-quinolinyl group, and an 8-quinolinyl group may be used. In addition, in the case of a group in which a plurality of rings are connected, such as a bipyridyl group, a bond is drawn from one ring, but may be bonded by another ring.

In addition, the groups exemplified above may be substituted with an alkyl group or a cycloalkyl group, preferably a methyl group, an ethyl group, a propyl group, a butyl group, or a cyclohexyl group.

Ar ² is preferably a pyridyl group, quinolinyl group, isoquinolinyl group, quinoxanyl group, pyrimidyl group, phenanthrolinyl group, bipyridyl group, terpyridyl group, acridyl group, benzo [d] imidazolyl group, imidazo [1,2-a ] A pyridyl group and a group in which these are substituted with an alkyl group or a cycloalkyl group, preferably a methyl group or a cyclohexyl group. More specifically, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-quinolinyl group, 3-quinolinyl group, 6-quinolinyl group, 1-isoquinolinyl group, 3-isoquinolinyl group, 2-quinoxanyl group, 5-pyrimidyl group, 2-phenanthrolinyl group, 1-benzo [d] imidazolyl group, 2-benzo [d] imidazolyl group, 2-imidazol [1,2-a] pyridyl group, 3-imidazolo [1, 2-a] pyridyl group, 3-methyl-2-pyridyl group, 4-methyl-2-pyridyl group, 5-methyl-2-pyridyl group, 6-methyl-2-pyridyl group, 2-methyl-3-pyridyl group Group, 4-methyl-3-pyridyl group, 5-methyl-3-pyridyl group, 6-methyl-3-pyridyl group, 2-methyl-4-pyridyl group, 3-methyl-4-pyridyl group, 4-methyl -2-Kinori Such group, more preferably 2-pyridyl, 3-pyridyl, 4-pyridyl group and the like can be mentioned.

The compound represented by the general formula (1) has a fluorene skeleton and an aromatic heterocyclic ring containing an electron-accepting nitrogen in the molecule, so that the electron transportability and electrochemical stability of the fluorene skeleton are high. And the high electron-accepting property of aromatic heterocycles containing electron-accepting nitrogen. Thereby, the compound represented by the general formula (1) exhibits a high electron injecting and transporting ability.

The compound represented by the general formula (1) has high carrier mobility and good carrier balance by having 1 to 5 aromatic heterocycles Ar ² containing electron-accepting nitrogen in the molecule. . Thus, the compound represented by the general formula (1) can improve the light emission efficiency of the light emitting element. Furthermore, since the compound represented by General formula (1) has high heat resistance, it can improve the durability of the light-emitting element. From the viewpoint of reducing the crystallinity and the effect of the substituent remarkably, the number of Ar ² is more preferably 1 or 2, and particularly preferably 1. When two or more Ar ² are present, Ar ² may be the same or different.

Furthermore, since the compound represented by the general formula (1) has a fluorene skeleton and a carbazole group in the molecule, stacking between molecules is suppressed and the film quality is stabilized. Moreover, the electrochemical stability with respect to a hole improves by having a carbazole group with hole tolerance. Thereby, the compound represented by the general formula (1) expresses higher electron injecting and transporting ability.

Moreover, it is desirable that R ⁷ in the general formula (2) is used for connection with L ¹ . In fluorene, the conjugated system easily spreads at the positions of R ² and R ⁷ , and the conjugated system is efficiently spread by using R ⁷ for connection to L ¹ . As a result, the compound represented by the general formula (1) becomes electrochemically stable and further improves the electron transport property, and thus exhibits a higher electron injecting and transporting ability.

Moreover, it is desirable that R ² in the general formula (2) is used for connection to L ² . In fluorene, the conjugated system easily spreads at the positions of R ² and R ⁷ , and the conjugated system is efficiently spread when R ² is used for connection with L ² . As a result, the compound represented by the general formula (1) becomes electrochemically stable and further improves the electron transport property, and thus exhibits a higher electron injecting and transporting ability.

Moreover, it is desirable that R ¹⁵ , R ¹⁸ or R ²¹ in the general formula (3) is used for connection with L ¹ . Since the positions of R ¹⁵ , R ^18, and R ²¹ are vulnerable to oxidation in carbazole, the compound represented by the general formula (1) becomes electrochemically stable by combining this position with a linking group, and is higher. Expresses electron injection and transport ability.

In addition, for example, R ⁷ is used for linking with L ¹ means that the position of R ⁷ of the benzene ring of the group represented by the general formula (2) and the group represented by the linking group L ¹ are directly bonded. To do.

L ¹ is preferably a substituted or unsubstituted arylene group having 5 to 12 nuclear carbon atoms. Since a carbazole group is vulnerable to oxidation, it is electrochemically more stable to bond via an arylene group than to bond directly to a fluorene skeleton. As a result, a high electron transporting property and a synergistic effect of the fluorene skeleton are produced, and a higher electron injecting and transporting ability is expressed.

L ² is preferably a substituted or unsubstituted arylene group having 5 to 12 nuclear carbon atoms. Since aromatic heterocycles containing electron-accepting nitrogen are vulnerable to oxidation, it is more electrochemically stable to bond via an arylene group than to bond directly to a fluorene skeleton. As a result, a high electron transporting property and a synergistic effect of the fluorene skeleton are produced, and a higher electron injecting and transporting ability is expressed.

In the compound represented by the general formula (1), R ¹ to R ²¹ are preferably groups selected from hydrogen, an alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group among the above. Furthermore, among R ⁹ to R ¹⁰ , among the above, an alkyl group, a cycloalkyl group, an aryl group or a heteroaryl group is preferable. R ²¹ is preferably an aryl group or a heteroaryl group among the above.

The compound represented by the general formula (1) is not particularly limited, but specific examples include the following.

A known method can be used for the synthesis of the compound represented by the general formula (1). Examples of the method for introducing a carbazole group into the fluorene skeleton include a method using a coupling reaction of a halogenated fluorene derivative and a substituted or unsubstituted carbazole boronic acid under a palladium catalyst or a nickel catalyst, but are not limited thereto. It is not something. In addition, as a method for introducing an aromatic heterocyclic ring containing electron-accepting nitrogen into the fluorene skeleton, for example, an aromatic heterocyclic ring containing a halogenated fluorene derivative and electron-accepting nitrogen under a palladium catalyst or a nickel catalyst may be used. Although the method using the coupling reaction of the boronic acid of a ring is mentioned, It is not limited to these. When an aromatic heterocyclic ring containing a carbazole group or electron-accepting nitrogen is introduced into the fluorene skeleton through an arylene group, an aryl boronic acid substituted with an aromatic heterocyclic ring containing a carbazole group or electron-accepting nitrogen is used. It may be used. Further, boronic acid esters may be used in place of the various boronic acids described above.

The compound represented by the general formula (1) is used as a light emitting device material. Here, the light emitting element material represents a material used for any layer of the light emitting element, and is a material used for a layer selected from a hole transport layer, a light emitting layer, and an electron transport layer, as will be described later. In addition, the material used for the protective film of a cathode is also included. By using the compound represented by the general formula (1) in any layer of the light-emitting element, a high light-emitting efficiency and a light-emitting element with a low driving voltage can be obtained.

Since the compound represented by the general formula (1) has high electron injection and transport ability, light emission efficiency, and thin film stability, it is preferably used for the light emitting layer or the electron transport layer of the light emitting element. In particular, since it has an excellent electron injecting and transporting capability, it is preferably used for the electron transporting layer.

Next, the light emitting element will be described in detail. The light-emitting element 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.

As the organic layer, in addition to the structure composed of only the light emitting layer, 1) a hole transport layer / light emitting layer / electron transport layer, 2) a light emitting layer / electron transport layer, 3) a hole transport layer / light emitting layer, etc. A configuration is mentioned. Each of the layers may be a single layer or a plurality of layers. When the hole transport layer and the electron transport layer have a plurality of layers, the layers in contact with the electrodes may be referred to as a hole injection layer and an electron injection layer, respectively. The hole injection material is included in the hole transport material, and the electron injection material is included in the electron transport material.

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, the substrate does not need to be glass, and for example, a plastic substrate may be used.

In the light emitting element, the anode and the cathode have a role for supplying a sufficient current for light emission of the element. In order to extract light, it is desirable that at least one of the anode and the cathode is transparent or translucent. Usually, the anode formed on the substrate is a transparent electrode.

The material used for the anode is preferably a material that can efficiently inject holes into the organic layer, and is transparent or translucent in order to extract light. Materials used for the anode include conductive metal oxides such as tin oxide, indium oxide, indium tin oxide (ITO), and zinc indium oxide (IZO); metals such as gold, silver, and chromium; copper iodide, copper sulfide, and the like Inorganic conductive compounds: conductive polymers such as polythiophene, polypyrrole, and polyaniline. Although not particularly limited, 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 electric resistance of the transparent electrode is not limited as long as it can supply a current sufficient for light emission of the element, but it is desirable that the resistance is low from the viewpoint of power consumption of the element. For example, an ITO substrate having a surface electrical resistance of 300Ω / □ or less can be used as a device electrode, but since it is now possible to supply a substrate of about 10Ω / □, 20Ω / □ or less. It is particularly desirable to use a low resistance substrate. The thickness of the anode can be arbitrarily selected according to the resistance value, but is often used between 100 and 300 nm.

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 laminates of these metals with low work function metals such as lithium, sodium, potassium, calcium and magnesium Etc. are preferable. Among these, a metal selected from aluminum, silver and magnesium is preferable from the viewpoints of electrical resistance, ease of film formation, film stability, luminous efficiency, and the like. In particular, it is preferable that the cathode is made of magnesium and silver because electrons can be easily injected into the electron transport layer and the electron injection layer and can be driven at a low voltage.

Furthermore, for cathode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium; alloys using these metals; inorganic compounds such as silica, titania and silicon nitride; polyvinyl alcohol, polychlorinated As a preferred example, organic polymer compounds such as vinyl and hydrocarbon polymer compounds are laminated on the cathode as a protective film layer. Moreover, the compound represented by General formula (1) can also be utilized as this 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 manufacturing method of these electrodes is not particularly limited, such as resistance heating, electron beam, sputtering, ion plating and coating.

The hole transport layer needs to efficiently transport holes injected from the anode between electrodes to which an electric field is applied. Therefore, it is desirable that the hole transport material has high hole injection efficiency and efficiently transports the injected holes. For this purpose, the hole transport material must have an appropriate ionization potential, have a high hole mobility, have excellent stability, and be a substance that does not easily generate trapping impurities during manufacturing and use. Is done. The substance satisfying such conditions is not particularly limited, but 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; heterocyclic compounds such as benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives; fullerene derivatives; polymers In the system, the polycarbonate having the monomer in the side chain Sulfonate and styrene derivatives; or polythiophene, polyaniline, polyfluorene, polyvinylcarbazole and polysilane are preferred.

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

R ²² to R ²⁷ may be the same or different and are a group selected from the group consisting of halogen, sulfonyl group, carbonyl group, nitro group, cyano group and trifluoromethyl group.

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

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 light emitting layer may be either a single layer or a plurality of layers. The light emitting material may be a mixture of a host material and a dopant material, or a host material alone. 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 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 with a layer made of the host material or may be dispersed in the host material. The emission color can be controlled by mixing the host material and the dopant material. In this case, if the amount of the dopant material is too large, a concentration quenching phenomenon occurs. Therefore, the dopant material is preferably used in an amount of 20% by weight or less, more preferably 10% by weight or less based on the host material. As a method of mixing the host material and the dopant material, the host material and the dopant material may be co-evaporated, or the host material and the dopant material may be mixed in advance and then evaporated.

Specific examples of the light-emitting material include condensed ring derivatives such as anthracene and pyrene; metal chelated oxinoid compounds such as tris (8-quinolinolato) aluminum; bisstyryl derivatives such as bisstyrylanthracene derivatives and distyrylbenzene derivatives; Tetraphenylbutadiene derivative, indene derivative, coumarin derivative, oxadiazole derivative, pyrrolopyridine derivative, perinone derivative, cyclopentadiene derivative, oxadiazole derivative, thiadiazolopyridine derivative, dibenzofuran derivative, carbazole derivative, indolocarbazole derivative; polymer In the system, polyphenylene vinylene derivatives, polyparaphenylene derivatives, and polythiophene derivatives can be used, but are not particularly limited.

The compound represented by the general formula (1) is also preferably used as a light emitting material because it has high light emitting performance. Since the compound represented by the general formula (1) exhibits strong light emission in the ultraviolet to blue region (300 to 450 nm region), it can be suitably used as a blue light emitting material. Although the compound represented by the general formula (1) may be used as a dopant material, it is preferably used as a host material because it is excellent in thin film stability. In addition, since the compound represented by the general formula (1) has high luminous efficiency, high triplet level, bipolar property (both charge transport properties) and thin film stability, the phosphorescent dopant is particularly preferable. It is preferable to use as a host material to be combined with.

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, but is a compound having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, indene and the like; N, N′-dinaphthyl- Aromatic amine derivatives such as N, N′-diphenyl-4,4′-diphenyl-1,1′-diamine; metal chelated oxinoid compounds such as tris (8-quinolinato) aluminum (III); distyrylbenzene Bisstyryl derivatives such as derivatives; tetraphenylbutadiene derivatives, indene derivatives, coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, pyrrolopyrrole derivatives, thiadiazolopyridines Derivatives, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives; in the polymer system, polyphenylene vinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinyl carbazole derivatives, polythiophene derivatives, etc. can be used, but are particularly limited is not. Among these, metal chelating oxinoid compounds, dibenzofuran derivatives, carbazole derivatives, indolocarbazole derivatives, triazine derivatives, and the like are preferably used as the host material used when the light emitting layer emits phosphorescence.

The dopant material is not particularly limited, but is a compound having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, triphenylene, perylene, fluoranthene, fluorene, indene or a derivative thereof (for example, 2- (benzothiazole-2- Yl) -9,10-diphenylanthracene, 5,6,11,12-tetraphenylnaphthacene); furan, pyrrole, thiophene, silole, 9-silafluorene, 9,9'-spirobisilafluorene, benzothiophene , Benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyridine, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, thioxanthene, etc. And its derivatives; borane derivatives; distyrylbenzene derivatives; 4,4′-bis (2- (4-diphenylaminophenyl) ethenyl) biphenyl, 4,4′-bis (N- (stilben-4-yl) -N -Aminostyryl derivatives such as phenylamino) stilbene; aromatic acetylene derivatives; tetraphenylbutadiene derivatives; stilbene derivatives; aldazine derivatives; pyromethene derivatives; diketopyrrolo [3,4-c] pyrrole derivatives; , 4H-tetrahydro-9- (2′-benzothiazolyl) quinolidino [9,9a, 1-gh] coumarin derivatives such as coumarin; azole derivatives such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, triazole and the like A metal complex; and , N'- diphenyl -N, etc. N'- di (3-methylphenyl) -4,4'-aromatic amine derivative typified by diphenyl 1,1'-diamine.

In addition, as a dopant material used when the light emitting layer emits phosphorescence, iridium (Ir), ruthenium (Ru), palladium (Pd), platinum (Pt), osmium (Os), and rhenium (Re) are used. It is preferably a metal complex compound containing at least one metal selected from the group consisting of 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 between the required emission color, device performance, and host compound.

The electron transport layer is a layer in which electrons are injected from the cathode and further transports electrons. The electron transport layer has high electron injection efficiency, and it is desired to efficiently transport injected electrons. Therefore, the electron transport material 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 low molecular weight compound is likely to be deteriorated due to crystallization or the like. Therefore, a compound having a molecular weight of 400 or more is preferable in order to maintain a stable film quality. On the other hand, considering the transport balance between holes and electrons, if the electron transport layer plays a role in efficiently preventing holes from the anode from flowing to the cathode side without recombination, the electron transport capability is Even if the electron transport layer is made of a material that is not so high, the effect of improving the light emission efficiency is equivalent to that of a material made of a material having a high electron transport capability.

The electron transport material need not be limited to one kind, and a plurality of compounds may be mixed and used. The electron transport material is not particularly limited, but is a compound having a condensed aryl ring such as naphthalene, anthracene, or pyrene or a derivative thereof; a styryl aromatic ring derivative represented by 4,4′-bis (diphenylethenyl) biphenyl; Perylene derivatives; perinone derivatives; coumarin derivatives; naphthalimide derivatives; quinone derivatives such as anthraquinone and diphenoquinone; phosphoroxide derivatives; carbazole derivatives; indole derivatives; quinolinol complexes such as tris (8-quinolinolato) aluminum (III); hydroxyphenyloxazole complexes And the like, such as hydroxyazole complexes; azomethine complexes; tropolone metal complexes; and flavonol metal complexes.

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

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. That is, in the light emitting device of the present invention, the electron transport layer more preferably contains a donor compound in order to improve the electron transport capability in addition to the compound represented by the general formula (1).

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. Preferable types of alkali metals and alkaline earth metals include alkali metals such as lithium, sodium, and cesium that have a low work function and a large effect of improving the electron transport ability, and alkaline earth metals such as magnesium and calcium.

In addition, since the deposition in vacuum is easy and the handling is excellent, the donor compound is preferably in a state of an inorganic salt or a complex with an organic substance rather than a single metal. Furthermore, it is more preferable that it is in the state of a complex of a metal and an organic matter from the viewpoint of easy 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 , And carbonates such as Cs ₂ CO ₃ . A preferable example of the alkali metal or alkaline earth metal is lithium from the viewpoint that the raw materials are inexpensive and easy to synthesize. In addition, preferable examples of the organic substance in the complex of metal and organic substance include quinolinol, benzoquinolinol, flavonol, hydroxyimidazopyridine, hydroxybenzazole, hydroxytriazole and the like. Among these, a complex of an alkali metal and an organic substance is preferable, a complex of lithium and an organic substance is more preferable, and lithium quinolinol is particularly preferable.

In addition, when 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 to the electron transport layer increases, and the cathode and the electron injection layer or the electron injection layer and the electron transport. The energy barrier between layers is reduced and the driving voltage is lowered. The preferred doping concentration varies depending on the material and the film thickness of the doping region, but the electron transport layer is deposited by vapor deposition so that the deposition rate ratio of the electron transport material and the donor compound is in the range of 100: 1 to 1: 100. It is preferable to form. The deposition rate ratio is more preferably 10: 1 to 1:10, and particularly preferably 7: 3 to 3: 7.

The method of improving the electron transport ability by doping a donor compound in the electron transport layer is particularly effective when the organic layer is thick. The effect is particularly great when the total thickness of the electron transport layer and the light emitting layer is 50 nm or more. For example, there is a method of using the interference effect to improve the light emission efficiency, but this improves the light extraction efficiency by matching the phase of the light directly emitted from the light emitting layer and the light reflected by the cathode. Is the method. The optimum conditions vary depending on the light emission wavelength, but the total film thickness of the electron transport layer and the light emitting layer may be 50 nm or more. In the case where the light emission is long wavelength light emission such as red, the total film thickness of the electron transport layer and the light emitting layer may be a thick film near 100 nm.

When doping a donor compound, the thicker the electron transport layer, the higher the doping concentration. Doping may be performed on a part or all of the electron transport layer. However, when doping a part of the electron transport layer, providing a doping region at least at the electron transport layer / cathode interface is effective in reducing the voltage. Is desirable because it is obtained. In addition, when the light emitting layer is doped with the donor compound, it is desirable to provide a non-doped region at the light emitting layer / electron transport layer interface when adversely affecting the light emission efficiency.

The formation method of each of the above layers constituting the light emitting element is not particularly limited, such as resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination method, and coating method, but resistance heating vapor deposition or electron beam vapor deposition is preferable from the viewpoint of element characteristics.

The total thickness of the organic layer cannot be limited because it depends on the resistance value of the light-emitting substance, 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 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 matrix type and / or segment type display, for example.

The matrix method is a method in which 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 used for displaying images and characters on a personal computer, monitor, TV, and a pixel with a side of mm order is used 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, typical pixel arrangements include a delta type and a stripe type. The matrix driving method may be either line sequential driving or active matrix. The line-sequential drive has a simple display structure, but the active characteristics of the active matrix are better, so it is necessary to use them properly depending on the application.

The segment method is a method in which a pattern is formed so as to display predetermined information and a region determined by the arrangement of the pattern is caused to emit light. Examples of segment-type displays include time and temperature displays on digital clocks and thermometers, operating status displays for audio equipment and electromagnetic cookers, and car panel displays. The matrix display and the segment display may coexist in the same panel.

The light-emitting element of the present invention is also preferably used as a backlight for various devices. The backlight is used mainly for the purpose of improving the visibility of a display device that does not emit light, and is used for a liquid crystal display device, a clock, an audio device, an automobile panel, a display panel, a sign, and the like. In particular, the light-emitting element of the present invention is preferably used for a backlight for a liquid crystal display device, especially 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.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Synthesis example 1
Synthesis of Compound [1] To a solution composed of 25.0 g of 2-bromofluorene, 12.2 g of iodine and 680 ml of acetic acid, 68 mL of sulfuric acid was slowly added under a nitrogen stream. After slowly adding 7.1 g of sodium nitrite to this mixed solution, the mixture was stirred for 2 hours under reflux. After the reaction mixture was cooled to room temperature, the precipitate was filtered. The obtained precipitate was washed with ethyl acetate, water and methanol, respectively, and vacuum-dried to obtain 25.9 g (yield 68%) of 2-bromo-7-iodofluorene.

Next, a solution of 19.6 g of potassium tert-butoxide and 317 mL of dimethyl sulfoxide was cooled to 0 ° C. under a nitrogen stream, and 25.9 g of 2-bromo-7-iodofluorene was added. 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 over magnesium sulfate, filtered through a silica pad, and the filtrate was evaporated. 50 ml of methanol was added to the obtained solid and filtered. Further, the solid was redissolved in toluene, filtered through a silica pad, and the filtrate was evaporated. The precipitate was filtered and dried under vacuum to obtain 21.5 g (yield 77%) of 2-bromo-7-iodo-9,9-dimethylfluorene.

Next, a mixed solution of 10.0 g of 2-bromo-7-iodo-9,9-dimethylfluorene, 7.9 g of 3- (9-carbazolyl) phenylboronic acid, 125 mL of dimethoxyethane and 37 mL of 1.5 M aqueous sodium carbonate solution was added. After nitrogen substitution, 176 mg of bis (triphenylphosphine) palladium dichloride was added, and the mixture was heated and stirred at 60 ° C. for 6 hours. The reaction mixture was cooled to room temperature and extracted with 200 ml of toluene. The obtained organic layer was washed with 100 ml of water three times, dried over sodium sulfate, and then filtered. The filtrate was evaporated and purified by silica gel column chromatography, and the eluate was evaporated. 50 ml of methanol was added to the obtained solid, filtered, and then vacuum-dried to obtain 10.5 g of intermediate (A) (yield 81%).

Next, a mixed solution of 6.0 g of intermediate (A), 2.0 g of 4-chlorophenylboronic acid, 58 mL of dimethoxyethane and 17 mL of 1.5 M aqueous sodium carbonate solution was purged with nitrogen, and then 82 mg of bis (triphenylphosphine) palladium dichloride. And stirred under reflux for 6 hours and a half. The reaction mixture was cooled to room temperature and extracted with 750 mL of toluene. The obtained organic layer was washed with 100 ml of water three times, dried over sodium sulfate, and then filtered. The filtrate was evaporated and purified by silica gel column chromatography, and the eluate was evaporated. 20 ml of methanol was added to the obtained solid, filtered, and then vacuum-dried to obtain 5.7 g of intermediate (B) (yield 89%).

Next, a mixed solution of 3.0 g of intermediate (B), 0.74 g of 3-pyridineboronic acid, 36 mg of bis (dibenzylideneacetone) palladium, 49 mg of tricyclohexylphosphine tetrafluoroborate and 28 ml of 1,4-dioxane was added to nitrogen. After the substitution, 7.4 ml of 1.27M tripotassium phosphate aqueous solution was added, and the mixture was heated and stirred for 7 hours under reflux in a nitrogen stream. After the reaction mixture was cooled to room temperature, 28 ml of water was added, and the precipitate was filtered and dried with a vacuum dryer. The precipitate was purified by silica gel column chromatography, and the eluate was evaporated. 20 ml of methanol was added to the obtained solid and filtered. The solid was vacuum dried and purified by recrystallization using 65 mL of o-xylene to obtain 2.2 g of white crystals (yield 67%).

The results of ¹ H-NMR analysis of the obtained white crystals are as follows, and it was confirmed that the white crystals obtained above were 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).

Compound [1] was used as a light emitting device material after sublimation purification at about 310 ° 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 99.7% after sublimation purification.

Synthesis example 2
Synthesis of Compound [2] After substituting a mixed solution of 2.4 g of intermediate (A), 2.1 g of 4- (4-pyridyl) phenylboronic acid pinacol ester, 24 mL of dimethoxyethane and 7 mL of 1.5 M aqueous sodium carbonate solution with nitrogen , 33 mg of bis (triphenylphosphine) palladium dichloride was added, and the mixture was stirred with heating under reflux for 12 and a half hours. The reaction mixture was cooled to room temperature, 24 mL of water was added, and the precipitate was filtered and dried in vacuo. The precipitate was purified by silica gel column chromatography. To the eluate, 0.5 g of QuadraSil (registered trademark) was added as a scavenger, stirred for 1 hour at room temperature, filtered through a silica pad, and the solvent was distilled off. The obtained solid was recrystallized using 73 mL of o-xylene to obtain 2.2 g of white crystals (yield 73%).

The results of ¹ H-NMR analysis of the obtained white crystals are as follows, and it was confirmed that the white crystals obtained above were 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).

Compound [2] was used as a light emitting device material after sublimation purification at about 310 ° 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 99.9% before sublimation purification and 99.9% after sublimation purification.

Synthesis example 3
Synthesis of Compound [3] 2-Bromo-7-iodo-9,9-dimethylfluorene (11.5 g), 4- (9-carbazolyl) phenylboronic acid (9.1 g), dimethoxyethane (144 mL) and 1.5 M aqueous sodium carbonate solution (42 mL) The mixed solution was purged with nitrogen, 202 mg of bis (triphenylphosphine) palladium dichloride was added, and the mixture was heated and stirred at 60 ° C. for 5.5 hours. After the reaction mixture was cooled to about 40 ° C., 200 mL of water was added, and the precipitate was filtered. The precipitate was washed with methanol, filtered and dried in vacuo. The precipitate was purified by silica gel column chromatography, and the eluate was evaporated. 100 ml of methanol was added to the obtained solid, filtered, and vacuum-dried to obtain 10.1 g of intermediate (C) (yield 68%).

A mixed solution of Intermediate (C) ｇ 5.1 g, 4- (3-pyridyl) phenylboronic acid pinacol ester 3.5 g, dimethoxyethane 49 mL, 1.5 M aqueous sodium carbonate solution 14 mL was purged with nitrogen, and then bis (triphenylphosphine). ) Palladium dichloride (138 mg) was added, and the mixture was stirred with heating under reflux for 7 and a half hours. After the reaction mixture was cooled to room temperature, the precipitate was filtered and dried in vacuo. The precipitate was dissolved in 500 mL of THF, added with 0.5 g of activated carbon and 0.8 g of QuadraSil (registered trademark), stirred at room temperature for 1 hour, and then filtered through a silica pad. The eluate was evaporated. 20 ml of methanol was added to the obtained solid and filtered. The solid was vacuum dried and recrystallized using 120 mL of N, N-dimethylformamide. Furthermore, recrystallization was performed using 105 mL of N, N-dimethylformamide to obtain 4.3 g (yield 75%) of pale yellow crystals.

The results of ¹ H-NMR analysis of the obtained pale yellow crystals were as follows, and it was confirmed that the pale yellow crystals obtained above were 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).

Compound [3] 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 99.9% before sublimation purification and 99.9% after sublimation purification.

Synthesis example 4
Synthesis of Compound [4] Intermediate (C) 5.1 g, 4- (2-pyridyl) phenylboronic acid 2.2 g, dimethoxyethane 49 mL and 1.5 M aqueous sodium carbonate solution 14 mL were mixed with nitrogen, 69 mg of (triphenylphosphine) palladium dichloride was added, and the mixture was stirred with heating under reflux for 4 and a half hours. After the reaction mixture was cooled to room temperature, 49 mL of water was added, and the precipitate was filtered and dried in vacuo. The precipitate was purified by silica gel column chromatography, 0.8 g of QuadraSil (registered trademark) was added to the eluate, and the mixture was stirred at room temperature for 1 hour and filtered through celite. After the filtrate was evaporated, 20 ml of methanol was added to the obtained solid and filtered. The filtrate was vacuum dried and recrystallized using 54 mL of N, N-dimethylformamide. Furthermore, recrystallization was performed using 46 mL of N, N-dimethylformamide to obtain 3.5 g of white crystals (yield 60%).

The results of ¹ H-NMR analysis of the obtained white crystals are as follows, and it was confirmed that the white crystals obtained above were 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).

Compound [4] 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 99.8% after sublimation purification.

Example 1
A glass substrate (manufactured by Geomat Co., Ltd., surface electrical resistance 11Ω / □, sputtered product) on which ITO transparent conductive film is deposited to 150 nm is cut into 38 × 46 mm, and then etched to form the ITO transparent conductive film in a predetermined electrode shape. Formed. 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. On the ITO transparent conductive film, copper phthalocyanine is first formed to a thickness of 10 nm as a hole injection layer by resistance heating, and 4,4′-bis (N- (1-naphthyl) -N— as a hole transport layer. Phenylamino) biphenyl was deposited to a thickness of 50 nm each. Next, as a light emitting layer, a layer in which the compound (H-1) as a host material and the compound (D-1) as a dopant material are mixed has a thickness of 40 nm so that the dopant concentration is 5% by weight. Vapor deposited. Next, a layer in which the compound [1] and lithium fluoride which is a donor compound are mixed as an electron transporting layer has a thickness of 20 nm at a deposition rate ratio of 1: 1 (0.05 nm / s: 0.05 nm / s). Vapor deposited and laminated.

Next, 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 form a cathode. 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 blue light emission with a driving voltage of 4.7 V and an external quantum efficiency of 5.4% was obtained.

Examples 2 to 27
A light emitting device was fabricated in the same manner as in Example 1 except that the materials described in Table 1 and Table 2 were used as the host material, the dopant material, and the electron transport layer. The results are shown in Tables 1 and 2. Compounds [5] to [19] and 2E-1 are the compounds shown below.

Comparative Examples 1-12
A light emitting device was produced in the same manner as in Example 1 except that the materials described in Table 2 were used as the host material, the dopant material, and the electron transport layer. The results are shown in Table 2. In Tables 1 and 2, compounds E-1, E-2, E-3, and E-4 are the compounds shown below.

Examples 28-38
A light emitting device was fabricated in the same manner as in Example 1 except that the materials described in Table 3 were used as the host material, the dopant material, and the electron transport layer. The evaluation results are shown in Table 3. In Table 3, compounds H-2 to H-8 and D-2 to D-10 are the compounds shown below.

Examples 39 to 46, Comparative Examples 13 to 20
A light emitting device was fabricated in the same manner as in Example 1 except that the materials described in Table 4 were used as the host material and the dopant material, and tris (8-quinolinolato) aluminum (Alq) was used as the electron transport layer. The evaluation results are shown in Table 4.

The present invention provides a light emitting device material that enables an organic thin film light emitting device that achieves both high luminous efficiency and low driving voltage, and a light emitting device using the same. The light emitting device material of the present invention can be preferably used for the electron transport layer or the light emitting layer of the light emitting device.

Claims (14)

1. Light emitting device material containing a compound represented by the following general formula (1):
   

   

   In the formula, Y is a group represented by the following general formula (2); Ar ¹ is a group represented by the following general formula (3); L ¹ is a single bond or a substituted or unsubstituted group having 5 to 12 nuclear carbon atoms. A group selected from an arylene group and a substituted or unsubstituted heteroarylene group; L ² is a group selected from a substituted or unsubstituted arylene group having 5 to 12 nuclear carbon atoms and a substituted or unsubstituted heteroarylene group; Ar also the n Ar ² is the same; ^2, aromatic heterocyclic group only consists group containing electron-accepting nitrogen, which is unsubstituted or substituted alkyl group or a cycloalkyl group; n is an integer from 1 to 5 May be different;
   

   

   R ¹ to R ¹⁰ may be the same or different and each represents hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether A group 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 and —P (═O) R ¹¹ R ¹² ; R ¹¹ and R ¹² are aryl groups R ¹ to R ¹² may form a ring with adjacent substituents; provided that any one of R ¹ to R ⁸ is a group selected from L ¹ and a heteroaryl group; Used for ligation, and any other one is used for ligation with L ² ;
   

   

   R ¹³ to R ²¹ may be the same or different and each is 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 are adjacent to each other The substituents may form a ring; however, any one of R ¹³ to R ²¹ is used for linking to L ¹ .
2. An aromatic heterocyclic group containing an electron-accepting nitrogen is a pyridyl group, a quinolinyl group, an isoquinolinyl group, a quinoxanyl group, a pyrazinyl group, a pyrimidyl group, a pyridazinyl group, a phenanthrolinyl group, an imidazopyridyl group, a triazyl group, an acridyl group, or a benzoimidazolyl group The light emitting device material according to claim 1, which is selected from the group consisting of a group, a benzoxazolyl group, a benzothiazolyl group, a bipyridyl group, and a terpyridyl group.
3. The light emitting device material according to claim 1, wherein Ar ² is selected from the group consisting of the following groups:
   

   

   

   

   

   However, these groups may be substituted with an alkyl group or a cycloalkyl group.
4. The light emitting device material according to claim ¹ , wherein R ⁷ in the general formula (2) is used for connection with L ¹ .
5. The light emitting device material according to any one of claims 1 to 4, wherein R ² in the general formula (2) is used for connection with L ² .
6. 6. The light emitting device material according to claim 1, wherein R ¹⁵ , R ¹⁸ or R ²¹ in the general formula (3) is used for connection to L ¹ .
7. 7. The light emitting device material according to claim 1, wherein L ¹ is a substituted or unsubstituted arylene group having 5 to 12 nuclear carbon atoms.
8. The light emitting device material according to any one of claims 1 to 7, wherein L ² is a substituted or unsubstituted arylene group having 5 to 12 nuclear carbon atoms.
9. 9. A light-emitting element in which an organic layer is present between an anode and a cathode and emits light by electric energy, wherein the organic layer contains the light-emitting element material according to claim 1.
10. The light emitting device according to claim 9, wherein the organic layer includes an electron transport layer, and the electron transport layer includes the light emitting device material according to any one of claims 1 to 8.
11. The light emitting device according to claim 10, wherein the electron transport layer further contains a donor compound.
12. The donor compound is 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 a complex of an alkaline earth metal and an organic substance. The light emitting device according to claim 11.
13. The light-emitting element according to claim 12, 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.
14. The light emitting device according to claim 9, wherein the organic layer includes a light emitting layer, and the light emitting layer includes the light emitting device material according to any one of claims 1 to 8.