JP5194649B2 - Light emitting device material and light emitting device - Google Patents

Description

  The present invention relates to a light emitting device material useful as a fluorescent dye or a charge transport material, and a light emitting device using the same. The light-emitting element of the present invention can be used in the fields of display elements, flat panel displays, backlights, illumination, interiors, signs, signboards, electrophotographic machines, optical signal generators, and the like.

  In recent years, research on organic thin-film light-emitting devices that emit light when electrons injected from a cathode and holes injected from an anode are recombined in an organic light-emitting body sandwiched between both electrodes has been actively conducted. This light-emitting element is characterized by being thin, capable of emitting high-luminance under a low driving voltage, and capable of emitting multicolor light by selecting a light-emitting material.

C. of Eastman Kodak Company W. Since Tang et al. Have shown that organic thin-film light-emitting elements emit light with high brightness, many research institutions have studied this technology. A typical structure of the organic thin-film light-emitting device presented by the Kodak research group is a hole-transporting diamine compound, a light-emitting layer of tris (8-quinolinolato) aluminum (III), and a cathode. As described above, Mg: Ag (alloy) was sequentially provided, and green light emission of 1,000 cd / m ² was possible with a driving voltage of about 10 V (see Non-Patent Document 1).

  In addition, organic thin-film light-emitting elements can be obtained in various emission colors by using various fluorescent materials for the light-emitting layer, and therefore, researches for practical application to displays and the like are actively conducted. Among the three primary color luminescent materials, research on green luminescent materials is the most advanced. At present, intensive research is being conducted with the aim of improving the characteristics of red and blue luminescent materials.

One of the biggest problems in organic thin-film light-emitting elements is the compatibility between the light-emitting efficiency and color purity of the element. In particular, with respect to blue light-emitting elements, there are few blue light-emitting materials that provide elements with high luminous efficiency and excellent color purity. For example, a technique using a styrylamine derivative (see Patent Document 1), a perylene derivative (see Patent Document 2), and an anthracene derivative (see Patent Document 3) as a blue guest material is disclosed. In addition, as a chrysene compound, an aromatic amine derivative in which a chrysene structure and an amine structure are linked (see Patent Document 4), or at least two chrysene bonds via at least one aryl group or heterocyclic group The technique using the chrysene compound (refer patent document 5) used for a blue light emitting element is disclosed. However, in both cases, the luminous efficiency and the color purity are not sufficiently compatible.
Applied Physics Letters, (USA), 1987, 51, 12, 913-915 JP-A-5-17765 JP 2003-86380 A JP-A-2005-47868 International Publication No. 04/044408 Pamphlet JP 2006-52324 A

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the problems of the prior art, and to provide a light emitting element material that enables a light emitting element with high luminous efficiency and excellent color purity, and a light emitting element using the same.

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

R ^{1 to} R ¹⁷ may be the same as or different from each other, and are hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether. group, an aryl group, a heteroaryl group, an amino group, a silyl group, and -P (= ^O) selected from the ^R 18 ^{R 1 9.} R ¹⁸ and R ¹⁹ are selected from aryl groups and heteroaryl groups. Either n of R ² or R ⁸ is used for linking to a bicyclic benzoheterocycle. n is an integer of 1-2 . X is selected from an oxygen atom, a sulfur atom, and —NR ²⁰ —. R ²⁰ is selected from hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an aryl group, and a heteroaryl group .

  The light-emitting element material of the present invention can provide a light-emitting element material having high light-emitting performance that can be used for a light-emitting element or the like. According to the present invention, a light emitting device having high luminous efficiency and excellent color purity can be obtained.

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

R ^{1 to} R ¹⁷ may be the same as or different from each other, and are hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether. It is selected from a ring structure formed between a group, an aryl group, a heteroaryl group, an amino group, a silyl group, —P (═O) R ¹⁸ R ¹⁹ , and an adjacent substituent. R ¹⁸ and R ¹⁹ are selected from aryl groups and heteroaryl groups. Any n of R ^{1 to} R ¹² are used for linking to a bicyclic benzoheterocycle. n is an integer of 1-4. X is selected from an oxygen atom, a sulfur atom, and —NR ²⁰ —. R ²⁰ is selected from hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an aryl group, and a heteroaryl group. R ²⁰ may combine with R ¹³ to form a ring.

  Among these substituents, the alkyl group is, for example, a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group. This may or may not have a substituent. There is no restriction | limiting in particular in the additional substituent in the case of being substituted, For example, an alkyl group, an aryl group, heteroaryl group etc. can be mentioned, This point is common also in the following description. The number of carbon atoms of the alkyl group is not particularly limited, but is usually in the range of 1 to 20 and more preferably 1 to 8 from the viewpoint of availability and cost.

  The cycloalkyl group represents a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclohexyl, norbornyl, adamantyl, etc., which may or may not have a substituent. Although carbon number of an alkyl group part is not specifically limited, Usually, it is the range of 3-20.

  The heterocyclic group refers to an aliphatic ring having atoms other than carbon, such as a pyran ring, a piperidine ring, and a cyclic amide, in the ring, which may or may not have a substituent. . Although carbon number of a heterocyclic group is not specifically limited, Usually, it is the range of 2-20.

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

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

  An alkynyl group shows the unsaturated aliphatic hydrocarbon group containing triple bonds, such as an ethynyl group, for example, and may or may not have a substituent. Although carbon number of an alkynyl group is not specifically limited, Usually, it is the range of 2-20.

  The alkoxy group refers to, for example, a functional group having an aliphatic hydrocarbon group bonded through an ether bond such as a methoxy group, an ethoxy group, or a propoxy group, and the aliphatic hydrocarbon group may have a substituent. It may not have. Although carbon number of an alkoxy group is not specifically limited, Usually, it is the range of 1-20.

  The alkylthio group is a group in which an oxygen atom of an ether bond of an alkoxy group is substituted with a sulfur atom. The hydrocarbon group of the alkylthio group may or may not have a substituent. Although carbon number of an alkylthio group is not specifically limited, Usually, it is the range of 1-20.

  An aryl ether group refers to a functional group to which an aromatic hydrocarbon group is bonded via an ether bond, such as a phenoxy group, and the aromatic hydrocarbon group may or may not have a substituent. Good. Although carbon number of an aryl ether group is not specifically limited, Usually, it is the range of 6-40.

  An aryl thioether group is one in which the oxygen atom of the ether bond of the aryl ether group is substituted with a sulfur atom. The aromatic hydrocarbon group in the aryl ether group may or may not have a substituent. Although carbon number of an aryl ether group is not specifically limited, Usually, it is the range of 6-40.

  The aryl group represents an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, an anthracenyl group, a phenanthryl group, a terphenyl group, or a pyrenyl group. The aryl group may be unsubstituted or substituted. Although carbon number of an aryl group is not specifically limited, Usually, it is the range of 6-40.

  A heteroaryl group is a cyclic aromatic group having one or more atoms other than carbon such as furanyl group, thiophenyl group, pyrrolyl group, benzofuranyl group, benzothiophenyl group, indolyl group, pyridyl group, quinolinyl group in the ring. This may or may not have a substituent. Although carbon number of a heteroaryl group is not specifically limited, Usually, it is 2 or more and 30 or less range.

The amino group, cyano group, and -P (= O) R ¹⁸ R ¹⁹ may or may not have a substituent. Examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group as described above.

R ¹⁸ and R ¹⁹ are groups selected from aryl groups and heteroaryl groups.

  A silyl group refers to, for example, a functional group having a bond to a silicon atom, such as a trimethylsilyl group, which may or may not have a substituent. Although carbon number of a silyl group is not specifically limited, Usually, it is the range of 3-20. The number of silicon is usually preferably in the range of 1 or more and 6 or less.

Moreover, arbitrary adjacent 2 substituents (for example, R ¹ and R ^{2 in} the general formula (1)) may be bonded to each other to form a conjugated or non-conjugated condensed ring. As a constituent element of the condensed ring, an element selected from nitrogen, oxygen, sulfur, phosphorus, and silicon may be included in addition to carbon. Further, the condensed ring may be further condensed with another ring.

The chrysene compound represented by the general formula (1) has a chrysene skeleton and 1 to 4 bicyclic benzoheterocycles in the molecule. Here, in the present invention, the bicyclic benzoheterocycle means an electron-donating condensed aromatic benzofuran ring (when X is an oxygen atom), a benzothiophene ring (when X is a sulfur atom) or an indole ring (where X is −). NR ²⁰ - refers to the case). Having 1 to 4 such bicyclic benzoheterocycles is preferable because the fluorescence quantum yield of the chrysene compound is excellent. Among them, it is more preferable that the number of bicyclic benzoheterocycles is in the range of 1 to 2 since high-purity blue light emission can be obtained. In addition, the bicyclic benzoheterocycle contained in a chrysene compound may be one type, and multiple types may be contained.

Any ^{one of} R ^{1 to} R ¹² is used for linking with a bicyclic benzoheterocycle, but from the viewpoint of availability of raw materials, ease of synthesis, and further excellent fluorescence quantum yield and color purity, It is preferred that at least one of R ² or R ⁸ is used for linking with a bicyclic benzoheterocycle.

  Furthermore, it is preferable that X in the general formula (1) is an oxygen atom because a higher fluorescence quantum yield is obtained.

  The chrysene compound represented by the general formula (1) has a high fluorescence quantum yield and excellent color purity. Therefore, when used as a light emitting device material, a light emitting device having high luminous efficiency and excellent color purity can be obtained. It becomes possible.

  Although it does not specifically limit as said chrysene compound, Specifically, the following examples are mentioned.

  A known method can be used for the synthesis of the chrysene compound represented by the general formula (1). A method for introducing a benzofuranyl group, a benzothiophenyl group, or an indolyl group into a chrysene skeleton is, for example, a cup of a halogenated chrysene derivative and a benzofuranyl metal complex, a benzothiophenyl metal complex, or an indolyl metal complex under a palladium or nickel catalyst. Examples include a method using a ring reaction, a method using a coupling reaction between a chrysenyl metal complex and a halogenated benzofuran derivative, a halogenated benzothiophene derivative, or a halogenated indole derivative under a palladium or nickel catalyst, but are not limited thereto. It is not something.

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

  The organic layer is composed of only the light-emitting layer, and 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. 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 are composed of a plurality of layers, the layers on the side in contact with the electrode may be referred to as the hole injection layer and the electron injection layer, respectively. The hole transport material and the electron injection material are included in the electron transport material, respectively.

  In the light emitting device of the present invention, a light emitting device material containing a chrysene compound represented by the general formula (1) is included in the organic layer. Here, the light emitting element material refers to a compound that participates in light emission in the light emitting element, and corresponds to either one that emits light by itself or one that assists in the light emission. Specifically, a hole transport material, a light emitting material, an electron transport material, and the like correspond to the light emitting element material.

  The light emitting device material of the present invention may be used as a hole transport material or an electron transport material, but is preferably used as a light emitting material because of its high light emission performance. The light-emitting element material of the present invention is preferably used as a blue light-emitting material because it exhibits strong light emission in the blue region, but can also be used as a material for green to red light-emitting elements and white light-emitting elements. A white light emitting element is obtained by laminating a plurality of materials having different emission colors. Specifically, a two-layer laminated system of a light blue light emitting material and an orange light emitting material, and a three-layer laminated system of a blue light emitting material, a green light emitting material, and a red light emitting material can be given. Since the light emitting device material of the present invention is suitably used as a blue light emitting material, other different light emitting materials include, for example, 2,3,5,6-1H, 4H-tetrahydro-9- (2′-benzothiazolyl) quinolizino. Green light-emitting materials such as [9,9a, 1-gh] coumarin, 1,3,5,7-tetra (4-t-butylphenyl) -8-phenyl-4,4-difluoro-4-bora-3a, A white light emitting element can be obtained by laminating three layers with a red light emitting material such as 4a-diaza-s-indacene.

  The anode is not particularly limited as long as it can efficiently inject holes into the organic layer, but a material having a relatively large work function is preferably used. Examples of the material for the anode include conductive metal oxides such as tin oxide, indium oxide, indium zinc oxide, and indium tin oxide (ITO), metals such as gold, silver, and chromium, copper iodide, and copper sulfide. Examples include inorganic conductive materials, conductive polymers such as polythiophene, polypyrrole, and polyaniline. These electrode materials may be used alone, or a plurality of materials may be laminated or mixed.

  The resistance of the anode is not limited as long as a current sufficient for light emission of the light emitting element can be supplied, but it is desirable that the resistance be low from the viewpoint of power consumption of the light emitting element. For example, if the resistance is 300Ω / □ or less, it functions as an electrode. However, since it is now possible to supply an ITO substrate of about 10Ω / □, it is possible to use a low resistance product of 100Ω / □ or less. Particularly desirable. The thickness of the anode can be arbitrarily selected according to the resistance value, but is usually used in a range of 100 to 300 nm.

In order to maintain the mechanical strength of the light emitting element, it is preferable to form the anode on the 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. The glass material is preferably alkali-free glass because it is better to have less ions eluted from the glass, but soda lime glass with a barrier coat such as SiO ₂ is also available on the market. it can. Furthermore, if the anode functions stably, the substrate does not have to be glass. For example, the anode may be formed on a plastic substrate. The method for forming the anode is not particularly limited, and for example, an electron beam method, a sputtering method, a chemical reaction method, or the like can be used.

  The material used for the cathode is not particularly limited as long as it can efficiently inject electrons into the organic layer, but platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium , Cesium, calcium and magnesium, and alloys thereof. Lithium, sodium, potassium, cesium, calcium, magnesium, or alloys containing these low work function metals are effective for increasing the electron injection efficiency and improving device characteristics. However, since these low work function metals are generally unstable in the atmosphere, the organic layer is doped with a small amount of lithium or magnesium (1 nm or less in the thickness gauge display of vacuum deposition) to stabilize the organic layer. A preferred example is a method for obtaining a high electrode. Also, an inorganic salt such as lithium fluoride can be used. Furthermore, for electrode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, inorganic substances such as silica, titania and silicon nitride, polyvinyl alcohol, polyvinyl chloride Lamination of organic polymer compounds such as hydrocarbon polymer compounds is a preferred example. The method for forming the cathode is not particularly limited, and for example, resistance heating, electron beam, sputtering, ion plating and coating can be used.

  The hole transport layer is formed by a method of laminating or mixing one or more hole transport materials or a method using a mixture of a hole transport material and a polymer binder. Alternatively, the hole transport layer may be formed by adding an inorganic salt such as iron (III) chloride to the hole transport material. The hole transport material is not particularly limited as long as it is a compound capable of forming a thin film, injecting holes from the anode, and further transporting holes. For example, 4,4′-bis (N- (3-methylphenyl) -N-phenylamino) biphenyl, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl, 4,4 Triphenylamine derivatives such as', 4 "-tris (3-methylphenyl (phenyl) amino) triphenylamine, biscarbazole derivatives such as bis (N-allylcarbazole) or bis (N-alkylcarbazole), pyrazoline derivatives, Heterocyclic compounds such as stilbene compounds, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, phthalocyanine derivatives, porphyrin derivatives, in the case of polymers, polycarbonates or styrene derivatives, polythiophene, polyaniline having the above monomers in the side chain , Polyfluorene, poly Such alkenyl carbazole and polysilane are preferred.

  The light emitting layer may be a mixture of a host material and a dopant material or a host material alone. Each of the host material and the dopant material may be one kind or a plurality of combinations. The dopant material may be included in the entire host material or may be partially included. The dopant material may be either laminated with the host material or dispersed in the host material. If the amount of the dopant material is too large, a concentration quenching phenomenon occurs, so that the amount is preferably 20% by weight or less, more preferably 10% by weight or less, based on the total of the host material and the dopant material. As a doping method, the dopant material may be formed by a co-evaporation method with the host material, or the host material and the dopant material may be mixed in advance before the deposition. The chrysene compound used as the light-emitting element material in the present invention may be used as a host material, but is preferably used as a dopant material because of its high fluorescence quantum yield.

  The ionization potential of the chrysene compound used in the present invention is not particularly limited, but is preferably 4.5 eV or more and 7.0 eV or less, and more preferably 5.4 eV or more and 6.4 eV or less. Note that the absolute value of the ionization potential may vary depending on the measurement method. The ionization potential of the present invention is a value obtained by measuring a thin film deposited to a thickness of 30 nm to 100 nm on an ITO glass substrate using an atmospheric type ultraviolet photoelectron analyzer (AC-1, manufactured by Riken Kikai Co., Ltd.). is there.

  As the dopant material, only one chrysene compound represented by the general formula (1) may be used, or a plurality of chrysene compounds may be mixed and used. One or more other dopant materials may be mixed with the chrysene compound represented by the general formula (1). As dopant materials that can be mixed, compounds having an aryl ring such as naphthalene, anthracene, chrysene, phenanthrene, pyrene, triphenylene, perylene, fluorene, and indene and derivatives thereof (for example, 2- (benzothiazol-2-yl) -9, 10-diphenylanthracene, 5,6,11,12-tetraphenylnaphthacene, etc.), furan, pyrrole, thiophene, silole, 9-silafluorene, 9,9′-spirobisilafluorene, benzothiophene, benzofuran, indole, Compounds having heteroaryl rings such as dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, thioxanthene, and derivatives thereof, distyrylbenzene derivatives, , 4′-bis (2- (4-diphenylaminophenyl) ethenyl) biphenyl, 4,4′-bis (N- (stilben-4-yl) -N-phenylamino) stilbene, and other aminostyryl derivatives, aromatic Acetylene derivatives, tetraphenylbutadiene derivatives, stilbene derivatives, aldazine derivatives, pyromethene derivatives, diketopyrrolo [3,4-c] pyrrole derivatives, 2,3,5,6-1H, 4H-tetrahydro-9- (2′-benzothiazolyl) Coumarin derivatives such as quinolidino [9,9a, 1-gh] coumarin, azole derivatives such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, triazole and their metal complexes and N, N′-diphenyl-N, N '-Di (3-methylphenyl)- And aromatic amine derivatives typified by 4'-diphenyl-1,1'-diamine.

  The host material contained in the light-emitting material is not particularly limited, but is a compound having a condensed aryl ring such as anthracene or pyrene or a derivative thereof, N, N′-dinaphthyl-N, N′-diphenyl-4,4′-diphenyl Aromatic amine derivatives such as -1,1'-diamine, metal chelated oxinoid compounds such as tris (8-quinolinato) aluminum (III), bisstyryl derivatives such as distyrylbenzene derivatives, tetraphenylbutadiene derivatives, indene derivatives , Coumarin derivatives, oxadiazole derivatives, pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, oxadiazole derivatives, carbazole derivatives, pyrrolopyrrole derivatives, in polymer systems, polyphenylene vinylene derivatives, polyparaphenylene derivatives, poly Fluorene derivatives, polyvinylcarbazole derivatives, and polythiophene derivatives are suitably used. Among them, it is preferable to use a condensed aromatic ring derivative having an electron donating property or a neutral substituent as a host because the effect of high luminous efficiency of the chrysene compound of the present invention becomes more remarkable. Specifically, it is preferable to use a compound selected from an anthracene compound, a pyrene compound, and a distyrylbenzene derivative as a host material because it becomes more efficient when combined with the chrysene compound of the present invention.

  The electron transport layer is a layer in which electrons are injected from the cathode and further transports electrons. The electron transport layer is desired to have high electron injection efficiency and efficiently transport injected electrons. Therefore, it is desirable that the electron transport layer is made of a material having a high electron affinity, a high electron mobility, excellent stability, and impurities that are traps are less likely to be generated during manufacture and use. However, considering the transport balance between holes and electrons, if the electron transport layer mainly plays a role of effectively preventing the holes from the anode from recombining and flowing to the cathode side, the electron transport Even if it is made of a material that does not have a high capability, the effect of improving the luminous efficiency is equivalent to that of a material that has a high electron transport capability.

  The electron transport material used for the electron transport layer is not particularly limited, but is a compound having a condensed aryl ring such as naphthalene or anthracene or a derivative thereof, or a styryl-based fragrance represented by 4,4′-bis (diphenylethenyl) biphenyl. Ring derivatives, perylene derivatives, perinone derivatives, coumarin derivatives, naphthalimide derivatives, quinone derivatives such as anthraquinone and diphenoquinone, phosphorus oxide derivatives, carbazole derivatives and indole derivatives, quinolinol complexes such as tris (8-quinolinolato) aluminum (III) and hydroxy Examples include hydroxyazole complexes such as phenyloxazole complexes, azomethine complexes, tropolone metal complexes, and flavonol metal complexes. Since the driving voltage can be reduced, the electron transport material is composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon and phosphorus, and a compound having a heteroaryl ring structure containing electron-accepting nitrogen is used. preferable.

  The electron-accepting nitrogen represents a nitrogen atom that forms a multiple bond with an adjacent atom. Since the nitrogen atom has a high electronegativity, the multiple bond has an electron-accepting property, has an excellent electron transporting ability, and can be used for an electron transporting layer to reduce the driving voltage of the light emitting element. Therefore, heteroaryl rings containing electron-accepting nitrogen have a high electron affinity. Examples of the heteroaryl ring containing an electron-accepting nitrogen include, for example, a pyridine ring, pyrazine ring, pyrimidine ring, quinoline ring, quinoxaline ring, naphthyridine ring, pyrimidopyrimidine ring, benzoquinoline ring, phenanthroline ring, imidazole ring, oxazole ring, Examples thereof include an oxadiazole ring, a triazole ring, a thiazole ring, a thiadiazole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, and a phenanthrimidazole ring.

  Examples of these compounds having a heteroaryl ring structure include benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, quinoline derivatives, benzoins. Preferred compounds include quinoline derivatives, imidazopyridine derivatives, oligopyridine derivatives such as bipyridine and terpyridine, quinoxaline derivatives and naphthyridine derivatives. Among them, imidazole derivatives such as tris (N-phenylbenzimidazol-2-yl) benzene, oxadiazole derivatives such as 1,3-bis [(4-tert-butylphenyl) 1,3,4-oxadiazolyl] phenylene, Triazole derivatives such as N-naphthyl-2,5-diphenyl-1,3,4-triazole, phenanthroline derivatives such as bathocuproine and 1,3-bis (1,10-phenanthroline-9-yl) benzene, 2,2 ′ A benzoquinoline derivative such as bis (benzo [h] quinolin-2-yl) -9,9′-spirobifluorene, 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1, Bipyridine derivatives such as 1-dimethyl-3,4-diphenylsilole, 1,3-bis (4 ′-(2,2 ′: 6′2 ″ -ta Terpyridine derivatives such as pyridinyl)) benzene, naphthyridine derivatives such as bis (1-naphthyl) -4- (1,8-naphthyridin-2-yl) phenylphosphine oxide are preferably used from the viewpoint of electron transporting capability. Furthermore, 1,3-bis (1,10-phenanthroline-9-yl) benzene, 2,7-bis (1,10-phenanthroline-9-yl) naphthalene, 1,3-bis (2-phenyl-1, Phenanthroline dimers such as 10-phenanthroline-9-yl) benzene, 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1,1-dimethyl-3,4-diphenylsilole, etc. This bipyridine dimer has a remarkably high luminous efficiency improvement effect when combined with a light emitting layer containing a chrysene compound represented by the general formula (1), and is particularly preferable.

  The electron transport material may be used alone, but two or more of the electron transport materials may be mixed and used, or one or more of the other electron transport materials may be mixed with the electron transport material. It is also possible to use a mixture with a metal such as an alkali metal or an alkaline earth metal. The ionization potential of the electron transport layer is not particularly limited, but is preferably 5.8 eV or more and 8.0 eV or less, and more preferably 6.0 eV or more and 7.5 eV or less.

  The method of forming each 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, coating method, ink jet method, printing method, laser induced thermal transfer method, etc. From this point, resistance heating vapor deposition or electron beam vapor deposition is preferable.

  The thickness of the organic layer depends on the resistance value of the luminescent material and cannot be limited, but is selected from 1 to 1000 nm. The film thicknesses of the light emitting layer, the electron transport layer, and the hole transport layer are each preferably 1 nm to 200 nm, and more preferably 5 nm to 100 nm.

  The light-emitting element of the present invention has a function of converting electrical energy into light. Here, a direct current is mainly used as the electric energy, but a pulse current or an alternating current can also be used. The current value and the voltage value are not particularly limited, but are preferably 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 element.

  The light emitting device of the present invention is suitably used as a display for displaying in a matrix and / or segment system, for example.

  In the matrix method, pixels for display are two-dimensionally arranged such as a lattice shape or a mosaic shape, and characters and images are displayed by a set of pixels. The shape and size of the pixel are determined by the application. For example, a square pixel with a side of 300 μm or less is usually used for displaying images and characters on a personal computer, monitor, TV, and a pixel with a side of mm order for a large display such as a display panel. become. In monochrome display, pixels of the same color may be arranged. However, in color display, red, green, and blue pixels are displayed side by side. In the case of color display, there are typically a delta type and a stripe type. The matrix driving method may be either line sequential driving or active matrix. In the line sequential drive, the structure of the light emitting element is simple, but the active matrix may be superior in consideration of operation characteristics. The driving method is properly used depending on the application.

  The segment method is a method in which a pattern is formed so as to display predetermined information, and an area determined by the arrangement of the pattern is caused to emit light. For example, the time and temperature display in a digital clock or a thermometer, the operation state display of an audio device or an electromagnetic cooker, the panel display of an automobile, etc. The matrix display and the segment display may coexist in the same panel.

  The light emitting device of the present invention is also preferably used as a backlight for various devices. The backlight is used mainly for the purpose of improving the visibility of a display device that does not emit light, and is used for a liquid crystal display device, a clock, an audio device, an automobile panel, a display panel, a sign, and the like. In particular, the light-emitting element of the present invention is preferably used for a backlight for liquid crystal display devices, especially for personal computers for which thinning is being studied. The light-emitting element of the present invention can provide a backlight that is thinner and lighter than conventional ones.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited by these Examples. In addition, the number of the compound in each following Example points out the number of the compound described in the above chemical formula. The evaluation method for structural analysis is shown below.

¹ H-NMR was measured with a deuterated chloroform solution using superconducting FTNMR EX-270 (manufactured by JEOL Ltd.).

  HPLC was measured with a 0.1 g / L chloroform solution using a high performance liquid chromatograph LC-10 (manufactured by Shimadzu Corporation). As a developing solvent for the column, a mixed solution of 0.1% phosphoric acid aqueous solution and acetonitrile was used.

Synthesis Example 1 (Synthesis Method of Compound [29])
A mixed solution of 1.2 g of chrysene, 2.2 g of N-bromosuccinimide and 52 ml of dimethylformamide was stirred at room temperature for 11 hours under a nitrogen stream. 50 ml of water was poured into the solution, and the precipitate was filtered. The solid filtered off was washed with 50 ml of water and 50 ml of methanol, respectively, and then vacuum-dried to obtain 1.4 g of 6,12-dibromochrysene as a milky white powder.

Next, 1.4 g of 6,12-dibromochrysene, 1.9 g of 2-benzofuranboronic acid, 4.9 g of tripotassium phosphate, 176 mg of PdCl ₂ (dppf) · CH ₂ Cl _{2 and} 36 ml of degassed dimethylformamide The mixed solution was heated and stirred at 100 ° C. for 3 hours under a nitrogen stream. After the solution was cooled to room temperature, 30 ml of water was poured and filtered. The obtained solid was washed with 30 ml of methanol, recrystallized from toluene, and vacuum dried to obtain 1.1 g of yellow crystals. The results of ¹ H-NMR analysis of the obtained powder are as follows, and it was confirmed that the yellow crystals obtained above were the compound [29].
¹ H-NMR (CDCl ₃ (d = ppm)): 7.27-7.44 (m, 6H), 7.68-7.84 (m, 8H), 8.61-8.65 (m, 2H), 8.96 (m, 2H), 9.16 ( s, 2H).

This compound [29] was used as a light emitting device material after sublimation purification at about 260 ° C. under a pressure of 1 × 10 ⁻³ Pa using an oil diffusion pump. The HPLC purity (area% at a measurement wavelength of 254 nm) was 99.6% before sublimation purification and 99.8% after sublimation purification.

Example 1
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam vapor-deposited product) on which an ITO transparent conductive film is deposited to 150 nm is cut to 30 × 40 mm, and the ITO conductive film is patterned by a photolithography method to produce a light emitting portion And the electrode extraction part was produced. The obtained substrate was ultrasonically cleaned with acetone, “Semicocrine 56” (manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes and then with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes and dried. Immediately before the device was fabricated, this substrate was subjected to UV-ozone treatment for 1 hour, further placed in a vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁵ Pa or less. By the resistance heating method, first, copper phthalocyanine was deposited as a hole injecting material at 10 nm, and 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl was deposited as a hole transporting material at 50 nm. Next, H-1 represented by the following formula as a host material and a compound [29] as a dopant material were vapor-deposited to a thickness of 35 nm so as to have a doping concentration of 2%. Next, as an electron transport material, E-1 represented by the following formula was laminated to a thickness of 20 nm. On the organic layer formed as described above, lithium fluoride was vapor-deposited to a thickness of 0.5 nm, and then aluminum was vapor-deposited with a thickness of 1000 nm to form a 5 × 5 mm square device. The film thickness referred to here is a display value of a crystal oscillation type film thickness monitor. When this light-emitting element was DC-driven at 10 mA / cm ² , high-efficiency light emission with a luminous efficiency of 3.3 lm / W and blue light emission with high color purity (0.15, 0.16) in CIE chromaticity coordinates were obtained. It was.

Comparative Example 1
A light emitting device was produced in the same manner as in Example 1 except that D-1 shown in the following formula was used as the dopant material. When this light emitting device was DC-driven at 10 mA / cm ² , a light emission efficiency of 1.6 lm / W and blue light emission of (0.15, 0.18) in CIE chromaticity coordinates were obtained.

Comparative Example 2
A light emitting device was produced in the same manner as in Example 1 except that D-2 shown by the following formula was used as the dopant material. When this light emitting device was DC-driven at 10 mA / cm ² , emission efficiency of 3.3 lm / W and blue-green light emission of (0.18, 0.38) in CIE chromaticity coordinates were obtained.

Comparative Example 3
A light emitting device was produced in the same manner as in Example 1 except that D-3 represented by the following formula was used as the dopant material. When this light emitting device was DC driven at 10 mA / cm ² , a light emission efficiency of 1.8 lm / W and a blue light emission with high color purity of (0.15, 0.15) in CIE chromaticity coordinates were obtained. It was.

Comparative Example 4
A light emitting device was produced in the same manner as in Example 1 except that D-4 represented by the following formula was used as the dopant material. When this light emitting device was DC-driven at 10 mA / cm ² , a light emission efficiency of 1.7 lm / W and a blue light emission of (0.15, 0.20) in CIE chromaticity coordinates were obtained.

Example 2
A light-emitting element was fabricated in the same manner as in Example 1 except that H-2 shown by the following formula was used as the host material. When this light emitting device was DC-driven at 10 mA / cm ² , a light emission efficiency of 3.5 lm / W and a blue light emission with a high color purity of (0.15, 0.16) in CIE chromaticity coordinates were obtained. It was.

Example 3
A light emitting device was produced in the same manner as in Example 1 except that H-2 was used as the host material, Compound [29] was used as the dopant material, and E-2 was used as the electron transport material. When this light emitting device was DC-driven at 10 mA / cm ² , a light emission efficiency of 2.4 lm / W and a blue light emission with a high color purity of (0.15, 0.16) in CIE chromaticity coordinates were obtained. It was.

Example 4
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam evaporation product) on which an ITO transparent conductive film is deposited to 150 nm is cut into 30 × 40 mm, and a 300 μm pitch (remaining width 270 μm) × 32 pieces is obtained by photolithography. Patterned into stripes. One side of the ITO stripe in the long side direction is expanded to a pitch of 1.27 mm (opening width 800 μm) in order to facilitate electrical connection with the outside. The obtained substrate was ultrasonically cleaned with acetone and “Semicocrine 56” (trade name, manufactured by Furuuchi Chemical Co., Ltd.) for 15 minutes, respectively, and then washed with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes and dried. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, placed in a vacuum deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 5 × 10 ⁻⁴ Pa or less. First, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl was deposited as a hole transport material by a resistance heating method to a thickness of 150 nm. Next, H-1 as a host material and compound [29] as a dopant material were deposited to a thickness of 35 nm so that the doping concentration was 2%. Next, E-1 was laminated to a thickness of 20 nm as an electron transport material. The film thickness referred to here is a crystal oscillation type film thickness monitor display value. Next, the mask provided with 16 250 μm openings (corresponding to the remaining width of 50 μm and 300 μm pitch) by wet etching on a 50 μm thick Kovar plate was replaced with a mask so as to be orthogonal to the ITO stripe in vacuum, It fixed with the magnet from the back surface so that a mask and an ITO board | substrate might closely_contact | adhere. Then, after 0.5 nm of lithium fluoride was deposited, 200 nm of aluminum was deposited to prepare a 32 × 16 dot matrix element. When this element was driven in matrix, characters could be displayed without crosstalk.

Claims (5)

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

(R ^{1 to} R ¹⁷ may be the same as or different from each other, hydrogen, alkyl group, cycloalkyl group, heterocyclic group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, alkylthio group, aryl ether group, aryl thioether group, an aryl group, a heteroaryl group, an amino group, a silyl group, and ^{-P (= O) R 18 .R} 18 and ^{R 19} are selected from among ^{R 1 9,} from among the aryl and heteroaryl groups Either n of R ² or R ⁸ is used for linking to a bicyclic benzoheterocycle, n is an integer of 1 to 2. X is an oxygen atom, a sulfur atom, —NR ^20. R ²⁰ is selected from among hydrogen, alkyl groups, cycloalkyl groups, heterocyclic groups, aryl groups, and heteroaryl groups . The light emitting device material according to claim 1, wherein X is an oxygen atom . At least a light-emitting layer is present between an anode and a cathode, a light emitting element which emits light by electric energy, light emitting device characterized by light-emitting element containing a light emitting device material according to any one of claims 1-2 . The light emitting element according to claim 3 , wherein the light emitting layer has a host material and a dopant material, and the light emitting element material represented by the general formula (1) is a dopant material. There is at least an electron transport layer between the light-emitting layer and the cathode, and the electron transport layer contains an electron-accepting nitrogen, and is further composed of an element selected from carbon, hydrogen, nitrogen, oxygen, silicon, and phosphorus. The light emitting device according to claim 3, comprising a compound having an aryl ring structure.