JP2005272803A - Organic material and organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic material excellent in durability, and to provide an organic electroluminescent element improved in a light-emitting lifetime by using the organic material. <P>SOLUTION: The organic material for the organic electroluminescent element is expressed by formula (1) [at least one of A<SP>1</SP>to A<SP>20</SP>is a substituent of formula (2) (Ar<SP>a</SP>and Ar<SP>b</SP>are each a substituted or unsubstituted aryl composed of not more than 30 carbon atoms) or a substituent of formula (3) (Ar<SP>c</SP>, Ar<SP>d</SP>and Ar<SP>e</SP>are each a substituted or unsubstituted aryl composed of not more than 30 carbon atoms)]. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic material and an organic electroluminescent element.

  In recent years, light and highly efficient flat panel displays have been actively researched and developed, for example, as screen displays for computers and televisions. The most representative display device, a cathode ray tube (CRT), is currently used most frequently as a display because of its high brightness and good color reproducibility. However, it is bulky, heavy and has high power consumption. .

  In addition, liquid crystal displays such as active matrix driving have been commercialized as lightweight and highly efficient flat panel displays. However, the liquid crystal display has a narrow viewing angle and is not self-luminous, so the backlight consumes a lot of power in an environment where the surroundings are dark, and the high-definition high-speed video signal expected to be put to practical use in the future. In addition, there are problems such as not having sufficient response performance. In particular, it is difficult to produce a display with a large screen size, and there are problems such as high cost.

  Thus, recently, an organic electroluminescent element (so-called organic EL element) using an organic material has attracted attention as a flat panel display that can solve these problems. That is, by using an organic compound as a light-emitting material, it is expected to realize a flat panel display that is self-luminous, has a high response speed, and has no viewing angle dependency.

  A general configuration of an organic electroluminescent element is formed by sandwiching an organic layer containing an organic material that emits light when an electric current is passed between a light-transmitting anode and a cathode made of a metal material. As the historical background of this organic electroluminescent device, first, the organic layer was provided with a two-layer structure of a thin film made of a hole transporting material and a thin film made of an electron transporting material, and sandwiched between the organic layers. An element structure has been developed that emits light by recombination of holes and electrons injected into the organic layer from the anode and the cathode, respectively (for example, see Non-Patent Document 1 below).

  Thereafter, an organic electroluminescent device having an organic layer having a three-layer structure of a hole transport material, a light emitting material, and an electron transport material was developed (for example, see Non-Patent Document 2 below), and a light emitting material was further incorporated in the electron transport material. The element structure etc. which were included were developed (for example, refer the following nonpatent literature 3). These studies have verified the possibility of light emission at low voltage and high brightness in organic electroluminescent devices, and research and development has been very active in recent years.

  FIG. 1 is a cross-sectional view showing one configuration example of such an organic electroluminescent element. The organic electroluminescent element 1 shown in this figure is provided on a transparent substrate 2 made of glass or the like, for example, and an anode 3 and an anode 3 made of ITO (Indium Tin Oxide: transparent electrode) provided on the substrate 2. The organic layer 4 is provided on the organic layer 4 and the cathode 5 is provided on the organic layer 4. The organic layer 4 has a configuration in which a hole injection layer 4a, a hole transport layer 4b, and an electron transporting light emitting layer 4c are sequentially stacked from the anode 3 side. In this organic electroluminescent element 1, electrons injected from the cathode 5 and holes injected from the anode 3 are recombined in the light emitting layer 4c, and light generated during the recombination is transmitted through the anode 3 to the substrate. It is taken out from the 2 side.

  As the organic electroluminescent element 1, in addition to the element having such a configuration, a structure in which a cathode, an organic layer, and an anode are sequentially laminated in order from the substrate side, or an upper electrode (upper part as a cathode or an anode) There is also a so-called top emission type organic electroluminescent element in which light is extracted from the upper electrode side opposite to the substrate by constituting the electrode) with a transparent material.

  In particular, in an active matrix type display device in which a thin film transistor (TFT) is provided on a substrate, a so-called TAC (Top) in which a top emission organic electroluminescence element is provided on a substrate on which a TFT is formed. Emitting Adoptive Current drive) structure is advantageous in improving the aperture ratio of the light emitting portion.

  Various studies have been made on the organic material in the organic electroluminescent element having such a configuration, and in particular, improvement has been made on styryl allene or anthracene derivatives for green color forming materials (for example, Non-Patent Document 4 below). reference).

  Moreover, an organic material having a fluoranthene structure has been reported as a green to green organic material. Typical derivatives thereof include fluoranthene having an amino group or an aryl group (for example, Patent Documents 1 to 4 below), and compounds having a benzofluoranthene structure as a substituent (for example, Patent Documents 5 and 6 below). It is shown. Furthermore, although there has been no report on an unsubstituted bifluoranthene compound applied as an organic material for an organic electroluminescent device, its synthesis and spectroscopic studies are already known (for example, the following non-patent documents) 5).

Applied Physics Letters (USA) 1987, 51, 12, p. 913-915 Japanese Journal of Applied Physics, 1988, 27, 2, p. 269-271 Journal of Applied Physics (USA) 1989, 65, 9, p. 3610-3616 Materials Science and Engineering: R: Reports Volume 39, Issues 5-6, Pages 143-222, 2002 Journal of the American Chemical Society (USA) 1968, Vol. 90, No. 3, p. 566-569 JP-A-10-125467 Japanese Patent Laid-Open No. 10-189248 JP 2002-43058 A JP 2003-81924 A JP 2001-257074 A JP 2002-69044 A

  By the way, since the organic electroluminescent element described above is a self-luminous element, when a display device is configured using the organic electroluminescent element, it is most important to make the organic electroluminescent element longer in life and to ensure reliability. One. For this reason, as described above, although research on organic materials constituting the organic electroluminescent device has been pursued, nothing has yet reached practicality in terms of light emission efficiency and light emission lifetime, and further improvements in device physical properties have been achieved. There is a need for improvement.

  Therefore, the present invention provides an organic material having excellent durability as an organic material constituting an organic layer of an organic electroluminescent element, and organic electroluminescence whose emission lifetime is improved by using this organic material. An object is to provide an element.

The organic material of the present invention for achieving such an object is an organic material for an organic electroluminescent element, and is represented by the following general formula (1).

ただし、一般式（２）中のＡｒ^aおよびＡｒ^bは、それぞれ独立に炭素数３０以下の置換あるいは無置換のアリール基を示し、一般式（３）中のＡｒ^c、Ａｒ^d、Ａｒ^eは、それぞれ独立に炭素数３０以下の置換あるいは無置換のアリール基を示す。 However, in the general formula (1), A ^{1 to} A ²⁰ are each independently hydrogen, halogen, hydroxyl group, substituted or unsubstituted carbonyl group having 20 or less carbon atoms, substituted or unsubstituted group having 20 or less carbon atoms. Carbonyl ester group, substituted or unsubstituted alkyl group having 20 or less carbon atoms, substituted or unsubstituted alkenyl group having 20 or less carbon atoms, substituted or unsubstituted alkoxyl group having 20 or less carbon atoms, substituted or unsubstituted 30 carbon atoms or less An unsubstituted aryl group, a substituted or unsubstituted heterocyclic group having 30 or less carbon atoms, a cyano group, a nitro group, or a silyl group, and at least one of A ^{1 to} A ²⁰ is represented by the following general formula (2) or The substituent of General formula (3) is shown.

However, Ar ^a and Ar ^b in the general formula (2) each independently represent a substituted or unsubstituted aryl group having 30 or less carbon atoms, and Ar ^c , Ar ^d , and Ar ^e in the general formula (3) are And each independently represents a substituted or unsubstituted aryl group having 30 or less carbon atoms.

  The carbonyl group includes an aldehyde group, a ketone group, and a carboxyl group. The alkyl group includes a linear alkyl group, a branched alkyl group, and a cyclic alkyl group.

In addition, as the substituents for the above-described substituents, that is, a carbonyl group, a carbonyl ester group, an alkyl group, an alkenyl group, an alkoxyl group, an aryl group, and a heterocyclic group, a halogen, a hydroxyl group, Examples thereof include a carbonyl group, a carbonyl ester group, a cyclic alkyl group, an alkenyl group, an alkoxy group, an aryl group, a heterocyclic group, a cyano group, a nitro group, and a silyl group. In particular, in the general formula (2), as a substituent for the aryl groups of Ar ^a and Ar ^b , in addition to the above-described substituents, a substituted or unsubstituted amino group can be selected.

  Moreover, this invention is also an organic electroluminescent element (organic EL element) using such an organic material. An organic electroluminescent element has an organic layer sandwiched between an anode and a cathode, and the organic layer is made of an organic material represented by the above general formula (1), general formula (2), and general formula (3). It is configured using. More specifically, the organic layer includes a hole transport layer and a light emitting layer that are configured using the organic material represented by the general formula (1), the general formula (2), and the general formula (3). In addition, it is preferable that the content rate of the organic material shown by General formula (1), General formula (2), and General formula (3) in a light emitting layer is 30 volume% or less.

  Since the organic material of the present invention having the above-described structure has the fluoranthene structure in the molecule, it has good thermal properties, excellent external force and thermal durability, and fluctuation due to voltage. It has stability in force. In particular, crystallization is unlikely to occur due to the effect of increasing the molecular weight by dimerizing fluoranthene into bifluoranthene. Moreover, since this organic material is in the form of an aromatic amine compound, good hole transportability can be obtained. Furthermore, green electroluminescence based on the high fluorescence characteristic of fluoranthene can be obtained.

  Therefore, the organic electroluminescent element of the present invention in which the organic layer is formed using such an organic material has excellent durability of the organic layer when driven for a long time. In particular, by using this organic material for the hole transport layer in the organic layer, the hole transport property in the hole transport layer is improved and the light emission efficiency is improved. And when this organic material is used for the light emitting layer of the organic layers, it also exhibits excellent light emission characteristics in the green light emitting region.

  As described above, since the durability of the organic layer can be improved by using the organic material of the present invention for the organic layer of the organic electroluminescent element, the emission lifetime of the organic electroluminescent element is improved. Is possible. In particular, by using this organic material for the light emitting layer constituting the organic layer, it becomes possible to improve the light emission efficiency in the green light emitting region. As a result, a full-color display with high color reproducibility can be achieved by configuring a pixel by combining a red light emitting element and a blue light emitting element together with the organic electroluminescent element.

  Hereinafter, the structures of the organic material and the organic electroluminescent element of the present invention will be described in more detail.

<Organic materials>
The organic material of the present invention represented by the above general formula (1), general formula (2), and general formula (3) is an aromatic amine-based bifluoranthene compound used in the organic layer of the organic electroluminescence device. The bifluoranthene compound has a plurality of isomers at each fluoranthene bonding position, but the organic material of the present invention includes all the structural isomers. That is, the organic material of the present invention includes all of the following 15 substitution combinations of isomers in view of the molecular symmetry of bifluoranthene.

a) 1, 1′-bifluoranthene; binding at A ³ site and A ⁶ site in general formula (1) b) 2, 2′-bifluoranthene; binding at A ⁴ site and A ⁵ site in general formula (1) c) 3,3′-bifluoranthene; binding at A ¹⁴ site and A ¹⁵ site in general formula (1) d) 7,7′-bifluoranthene; binding at A ² site and A ⁷ site in general formula (1) e) 8,8′-bifluoranthene; binding at A ¹ site and A ⁸ site in general formula (1) f) 1,2′-bifluoranthene; binding at A ³ site and A ⁵ site in general formula (1) g) 1,3′-bifluoranthene; binding at A ³ site and A ¹³ site in general formula (1) h) 1,7′-bifluoranthene; binding at A ³ site and A ⁷ site in general formula (1) i) 1,8′-bifluoranthene; bond at A ³ site and A ⁸ site of general formula (1) j) 2,3′-bifluoranthene; general formula (1) ) At the A ⁴ site and the A ¹³ site k) 2,7′-bifluoranthene; the bond at the A ⁴ site and the A ⁷ site of general formula (1) l) 2,8′-bifluoranthene; ) binding m in a ⁴ moiety and a ⁸ sites) 3,7'- Bifuruoranten; general formula (1) binds n in a ¹⁵ site and a ⁷ sites) 3,8'- Bifuruoranten; formula (1 ) coupling o in a ¹⁵ site and a ⁸ sites) 7,8'- Bifuruoranten; binding at a ² site and a ⁸ parts of the general formula (1)

  Hereinafter, a specific example of the organic material of the present invention will be described.

  As the bifluoranthene compound which is an organic material of the present invention, as shown in the structural formulas (1) to (12) of Table 1 below, for example, each substitution site of c) 3,3′-bifluoranthene is substituted with the above general formula ( An aromatic amine-based bifluoranthene compound substituted with diphenylamine which is one of 2) can be exemplified.

Among these, as shown in Structural Formula (5) to Structural Formula (12), at least one of the two substitution sites of bifluoranthene, in particular, each of the two fluoranthenes represented by General Formula (1), is represented by the above general formula ( A structure substituted with diphenylamine, which is one of 2), is exemplified as a more generally synthesizable structure. The easily synthesizeable structure includes 7 to 10 substitution sites of each fluoranthene (that is, one of A ¹ , A ² , A ¹⁹ and A ^{20 in} the general formula (1), and A ^{7 to} A A structure in which one of ¹⁰ ) is substituted with a substituent represented by the general formula (2) is exemplified.

  In addition, in the general formula (1), other than the portion substituted with the substituent represented by the general formula (2) (hereinafter referred to as other portion), as described above, other substituents may be substituted. It may be substituted with a group. For example, a compound in which another site is substituted with a branched alkyl group as in structural formula (9), a compound in which another site is substituted with a cyclic alkyl group as in structural formula (10), and a structural formula ( Examples are compounds in which other sites are substituted with aryl groups as in 11) and structural formula (12).

  Furthermore, as shown in the structural formulas (13) to (20) in Table 2 below, the substituent represented by the general formula (2) that substitutes each substitution site of 3,3′-bifluoranthene has 30 carbon atoms. The following aromatic amino groups are not limited to diphenylamine. Further, the substitution site of the aromatic amino group represented by the general formula (2) is the same as described with reference to Table 1.

  The organic material of the present invention has a structure in which one or more of the other sites in the structural formulas (13) to (20) are substituted with the substituent described in the general formula (2). Including. Further, as shown in the structural formula (16), the aromatic amino group represented by the general formula (2) is further substituted with another substituent (in this example, a branched alkyl group) as described above. Also good.

  The substitution state in the fluoranthene compound described above is applied not only to the 3,3′-bifluoranthene compound but also to the bifluoranthene in all the bonded states a) to o). For example, as shown in the structural formulas (21) to (26) in Table 3 below, compounds in which each substitution site of 2,2′-bifluoranthene is substituted with the substituent represented by the general formula (2), As shown in the structural formulas (27) to (29) of FIG. 3, even in a compound in which each substitution site of 8,8′-bifluoranthene is substituted with the substituent represented by the general formula (2), the above-described substitution state is Applied.

  And as shown to Structural formula (22), the substitution site | part of the aromatic amino group of General formula (2) with respect to a fluoranthene compound does not need to be the same position in each fluoranthene. Moreover, as shown in Structural Formula (23), two or more aromatic amino groups may be substituted only on one fluoranthene. Furthermore, as shown in the structural formula (24), the number of substitutions of the aromatic amino group of the general formula (2) for each fluoranthene may be different. Further, as shown in the structural formula (26), the aromatic amino group of the general formula (2) may be further substituted with another substituent (in this example, a linear alkyl group).

  Furthermore, as shown in the structural formulas (30) to (35) in Table 4 below, the aromatic amino group of the general formula (2) may be further substituted with an aromatic amino group.

  In the above, the bifluoranthene compound in which each substitution site of bifluoranthene is substituted with the aromatic amine represented by the general formula (2) is exemplified, but in addition to this, as the bifluoranthene compound which is the organic material of the present invention, As shown in structural formulas (36) to (40) in Table 5 and structural formulas (41) to (44) in Table 6 below, each substitution site of bifluoranthene is substituted with the substituent represented by the general formula (3). Substituted structures are illustrated.

  Note that the substitution state of the general formula (2) described above also applies to the compound in which each substitution site of bifluoranthene is substituted with the substituent represented by the general formula (3).

The organic material of the present invention shown as an example above can be synthesized by various methods, and examples include the following methods a) to c).
a) A synthesis method in which a halogenated fluoranthene is coupled by a Grignard reaction using magnesium.
b) A method in which halogenated fluoranthene is coupled by the Ullmann reaction in the presence of a copper catalyst.
c) A method of synthesizing boronic acid, or boronic esterified fluoranthene and halogenated fluoranthene by a transition metal catalyst typified by palladium (so-called Suzuki coupling reaction).

  The organic material comprising the bifluoranthene compound of the present invention is used as a material constituting the organic layer of the organic electroluminescent element, and it is preferable to increase the purity before subjecting it to the manufacturing process of the organic electroluminescent element. The purity should be 95% or more, more preferably 99% or more. As a method for obtaining such a high-purity organic compound, in addition to a recrystallization method, a reprecipitation method, which is a purification after the synthesis of the organic compound, or a column purification using silica or alumina, a known method by a sublimation purification or a zone melt method is used. High purity methods can be used.

  In addition, by repeating these purification methods or combining different purification methods, the mixture of unreacted substances, reaction byproducts, catalyst residues, or residual solvents in the organic material in the present invention is reduced, and more It is possible to obtain an organic electroluminescent element having excellent device characteristics.

Furthermore, this compound suppresses the deterioration reaction from oxidation and decomposition by taking the storage methods of a) to c) listed below from the external factors such as light and oxygen, and in particular, an organic compound composed of this organic material. In the electroluminescent element, not only can the light emission characteristics be improved, but also the effect of reducing the load on the manufacturing apparatus can be exhibited.
a) After synthesizing the organic material, immediately leave it in a cool place. The storage temperature is preferably in the range of -100 ° C to 100 ° C, more preferably in the temperature range of -50 ° C to 50 ° C.
b) After synthesizing the organic material, immediately store it in a light-shielding container.
c) After synthesizing the organic material, the synthesized organic material is stored in an inert gas atmosphere such as nitrogen, carbon dioxide, or argon.

  Since the organic material of the present invention described above has a fluoranthene structure in the molecule, it has good thermal properties, is excellent in external force and thermal durability, and is stable against fluctuations due to voltage. It has sex. In particular, crystallization is unlikely to occur due to the effect of increasing the molecular weight by dimerizing fluoranthene into bifluoranthene. Moreover, since this organic material is in the form of an aromatic amine compound, good hole transportability can be obtained. Furthermore, green electroluminescence based on the high fluorescence characteristic of fluoranthene can be obtained.

  Therefore, by using an organic material having such a structure in the organic layer of the organic electroluminescence device described below, it is possible to improve the durability of the organic layer and to improve the emission lifetime of the organic electroluminescence device. At the same time, it is possible to improve the light emission efficiency particularly in the light emission region from green to green.

  Further, by introducing an appropriate substituent having a defined number of carbon atoms as described above into this bifluoranthene, it becomes possible to further improve the light emission efficiency and the light emission lifetime.

  Moreover, the organic material which consists of a bifluoranthene compound based on this invention has both electron transport performance and hole transport performance. For this reason, as will be described in detail below, among the organic layers of the organic electroluminescence device, it can be used as a light emitting layer that also serves as an electron transporting layer or as a light emitting layer that also serves as a hole transporting layer. . And as above-mentioned, since hole transport property is especially favorable, it can use suitably as a material which comprises a hole transport layer. Moreover, it is also possible to use a structure in which the bifluoranthene compound according to the present invention is sandwiched between an electron transport layer and a hole transport layer as a light emitting layer.

<Organic electroluminescent device>
Next, the structure of the organic electroluminescent element (organic EL element) using the organic material described above will be described in detail with reference to FIG.

  The organic electroluminescent element 11 shown in FIG. 2 is configured as a top emission type element in which an anode 13, an organic layer 14, and a cathode 15 are laminated in this order on a substrate 12, and light is extracted from the side opposite to the substrate 12. ing.

  Here, the substrate 12 is a support on which the organic electroluminescence elements 11 are arranged and formed on one main surface side thereof, and may be a well-known one, for example, made of quartz, glass, metal foil, or resin. Of these, quartz and glass are preferable. In the case of resin, methacrylic resins represented by polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyethylene naphthalate (PEN) are used. ), Polyesters such as polybutylene naphthalate (PBN), polycarbonate resin, and the like, but it is necessary to perform a laminated structure and surface treatment that suppress water permeability and gas permeability.

  The anode 13 provided on the substrate 12 has a high work function from the vacuum level of the electrode material in order to inject holes efficiently, for example, chromium (Cr), molybdenum (Mo), tungsten (W). , Copper (Cu), silver (Ag), gold (Au), an alloy of tin oxide (SnO2) and antimony (Sb), an alloy of zinc oxide (ZnO) and aluminum (Al), and these metals, An alloy oxide or the like is used alone or in a mixed state. The anode 13 can be produced by, for example, a sputtering method.

  When the driving method of the display device configured using the organic electroluminescent element 11 is an active matrix method, the anode 13 is patterned for each pixel and connected to a driving thin film transistor provided on the substrate 12. It is provided in the state that was done. Further, although not shown here, an insulating film is provided on the anode 13, and the surface of the anode 13 of each pixel is exposed from the opening of the insulating film. And

  And the organic layer 14 provided on this anode 13 turns into a layer comprised using the organic material peculiar to this invention. The organic layer 14 is formed, for example, by laminating four layers of a hole injection layer 14a, a hole transport layer 14b, a light emitting layer 14c, and an electron transport layer 14d in this order from the anode 13 side.

  And in the organic electroluminescent element 11 of this invention, at least one layer of the positive hole transport layer 14b, the light emitting layer 14c, and the electron carrying layer 14d is comprised using the organic material mentioned above. In particular, the light emitting layer 14c is preferably configured using the organic material described above.

  Here, the hole injection layer 14a and the hole transport layer 14b are for increasing the efficiency of hole injection into the light emitting layer 14c, respectively. Examples of the material for the hole injection layer 14a or the hole transport layer 14b include benzine, styrylamine, triphenylamine, porphyrin, triazole, imidazole, oxadiazole, polyarylalkane, phenylenediamine, and arylamine. , Oxazole, anthracene, fluorenone, hydrazone, stilbene, or their derivatives, or heterocyclic conjugated monomers, oligomers or polymers such as polysilane compounds, vinylcarbazole compounds, thiophene compounds or aniline compounds. it can.

  Specifically, α-naphthylphenylphenylenediamine, porphyrin, metal tetraphenylporphyrin, metal naphthalocyanine, 4,4,4-tris (3-methylphenylphenylamino) triphenylamine, N, N, N ′, N '-Tetrakis (p-tolyl) p-phenylenediamine, N, N, N', N'-tetraphenyl-4,4'-diaminobiphenyl, N-phenylcarbazole, 4-di-p-tolylaminostilbene, poly (Paraphenylene vinylene), poly (thiophene vinylene), poly (2,2′-thienyl pyrrole) and the like are exemplified, but not limited thereto.

  The light emitting layer 14c is a region where holes and electrons are injected from each of the anode 13 and the cathode 15 when a voltage is applied by the anode 13 and the cathode 15, and these are recombined. Such a light emitting layer 14c is made of a material having high luminous efficiency, for example, an organic material such as a low molecular fluorescent dye, a fluorescent polymer, or a metal complex. Specifically, for example, anthracene, naphthalene, indene, phenanthrene, pyrene, naphthacene, triphenylene, chrysene, perylene, picene, fluoranthene, acephenanthrylene, pentaphen, pentacene, coronene, butadiene, coumarin, acridine, stilbene, or these Derivatives thereof, tris (8-quinolinolato) aluminum complex, bis (benzoquinolinolato) beryllium complex, tri (dibenzoylmethyl) phenanthroline europium complex ditoluyl vinylbiphenyl.

  Then, the organic material described using the general formula (1) is added to the light emitting layer 14c as a guest material (or dopant material). The amount of the organic material added at this time is 30% by volume or less.

  The electron transport layer 14d is for transporting electrons injected from the cathode 15 to the light emitting layer 14c. Examples of the material for the electron transport layer 14d include quinoline, perylene, bisstyryl, pyrazine, triazole, oxazole, oxadiazole, fluorenone, and derivatives thereof. Specific examples include tris (8-hydroxyquinoline) aluminum (abbreviated as Alq3), anthracene, naphthalene, phenanthrene, pyrene, chrysene, perylene, butadiene, coumarin, acridine, stilbene, or derivatives thereof.

  Each of these layers can be formed by a method such as a vacuum deposition method or a spin coating method. In particular, in the formation of the light emitting layer 14c, a small amount of fluorescent molecules may be co-deposited when the light emitting layer 14c is formed for the purpose of controlling the emission spectrum of the light emitting layer 14c. In this case, for example, the light emitting layer 14c may be formed of an organic thin film containing a trace amount of an organic substance such as a naphthalene derivative, anthracene derivative, pyrene derivative, naphthacene derivative, berylene derivative, coumarin derivative, or pyran dye as a fluorescent molecule. .

  The organic layer 14 is not limited to such a layer structure, and has at least the light emitting layer 14c and the hole transport layer 14a or the hole injection layer 14b between the anode 13 and the light emitting layer 14c. If it is a structure, the laminated structure as needed can be selected.

  The light emitting layer 14c may be provided in the organic electroluminescent element 11 as a hole transporting light emitting layer or an electron transporting light emitting layer. Furthermore, each layer constituting the organic layer 14 described above, for example, the hole injection layer 14a, the hole transport layer 14b, the light emitting layer 14c, and the electron transport layer 14d may have a laminated structure including a plurality of layers.

  And the organic compound which comprises such an organic layer 14 has the transport ability of an electron or a hole (hole) besides using the compound which light-emits fluorescence and phosphorescence by applying an electric field. A compound is appropriately used.

  Next, the cathode 15 provided on the organic layer 14 having such a configuration has, for example, a two-layer structure in which a first layer 15a and a second layer 15b are stacked in this order from the organic layer 14 side.

The first layer 15a is made of a material having a small work function and good light transmittance. Examples of such a material include lithium oxide (Li ₂ O) which is an oxide of lithium (Li), cesium oxide (Cs ₂ O) which is an oxide of cesium (Cs), and further, these oxides. Mixtures can be used. Further, the first layer 15a is not limited to such a material. For example, alkaline earth metals such as calcium (Ca) and barium (Ba), alkali metals such as lithium and cesium, and indium ( A metal having a low work function such as In) or magnesium (Mg), or an oxide of these metals may be used alone or as a mixture or alloy of these metals and oxides with increased stability. .

  The second layer 15b is constituted by a thin film using a light-transmitting layer such as MgAg. The second layer 15b may be a mixed layer containing an organic material such as an aluminum quinoline complex, a styrylamine derivative, or a phthalocyanine derivative. In this case, a layer having optical transparency such as MgAg may be additionally provided as the third layer.

  Each layer constituting the cathode 15 can be formed by a technique such as vacuum deposition, sputtering, or plasma CVD. Further, when the driving method of the display device configured using the organic electroluminescent element 11 is an active matrix method, the cathode 15 is formed by an organic layer 14 and the above-described insulating film, which is not shown here, by an anode. 13 is formed in a solid film shape on the substrate 12 in an insulated state and used as a common electrode of each pixel.

  The cathode 15 is not limited to the above laminated structure. This laminated structure is necessary when functional separation of each electrode layer (for example, functional separation between an inorganic layer that promotes electron injection and an inorganic layer that controls the electrode) is performed. Therefore, it is possible to configure only the second layer 15b, or to form a transparent electrode such as ITO after the first layer 15a is formed. Needless to say, the structure should be taken.

  The current applied to the organic electroluminescent element 11 having the above-described configuration is usually a direct current, but a pulse current or an alternating current may be used. The current value and the voltage value are not particularly limited as long as the elements are not interposed. However, considering the power consumption and life of the organic electroluminescent element, it is desirable to efficiently emit light with as little electrical energy as possible.

  The organic electroluminescence device shown in FIG. 1 may have a configuration in which light is extracted from both the upper and lower sides by using a transparent electrode made of ITO or the like for the anode 13.

Further, when the organic electroluminescent element 11 has a cavity structure, the total film thickness of the organic layer 14 and the electrode layer made of a transparent material or a semi-transparent material is defined by the emission wavelength, and multiple interference is calculated. Will be set to the value derived from. In a so-called TAC (Top Emitting Adoptive Current drive) structure in which a top emission type organic electroluminescence device is provided on a substrate on which a TFT is formed, light is extracted to the outside by actively using this cavity structure. It is possible to improve efficiency and control the emission spectrum.

  According to the organic electroluminescent element 11 having the above-described configuration, the organic layer 14 is configured using the bifluoranthene compound described using the general formula (1). Thereby, the durability and stability of the organic layer 14 can be improved, and electroluminescence based on the high fluorescence characteristic of fluoranthene can be obtained. As a result, it is possible to improve the light emission lifetime in the organic electroluminescent element 11 and to improve the light emission efficiency particularly in the green light emitting region.

  A full color display with high color reproducibility can be realized by configuring a pixel by combining a red light emitting element and a blue light emitting element together with the organic electroluminescent element of the present invention.

  In the above embodiment, only the use of the organic material of the present invention as a constituent material of a light emitting layer (including an electron transporting light emitting layer, a hole transporting light emitting layer, and a charge transporting light emitting layer) is described. did. However, since the organic material of the present invention is excellent in durability as described above and has an electron transporting property and a hole transporting property, this organic material is used as a layer other than the light emitting layer, For example, it can also be used as a material constituting an electron transport layer, a hole transport layer, a hole injection layer, and the like, thereby improving durability in these layers.

  Further, if the organic material of the present invention is in the form of an aromatic amine compound, good hole transportability can be obtained. By using this organic material, a hole transport layer is formed. The hole transport property of the hole transport layer is improved. As a result, the amount of holes injected into the light emitting layer can be increased to improve the light emission efficiency. In the case of forming a hole transport layer using this organic material, the aminobifluoranthene can be used alone, and other hole transport materials such as α-naphthylphenyl can be used as necessary. Phenylenediamine, porphyrin, metal tetraphenylporphyrin, metal naphthalocyanine, 4,4,4-tris (3-methylphenylphenylamino) triphenylamine, N, N, N ′, N′-tetrakis (p-tolyl) p -Phenylenediamine, N, N, N ', N'-tetraphenyl-4,4'-diaminobiphenyl, N-phenylcarbazole, 4-di-p-tolylaminostilbene, poly (paraphenylenevinylene), poly (thiophene) Vinylene) and poly (2,2′-thienylpyrrole) may be mixed at an appropriate ratio. This makes it possible to adjust the hole movement.

  Further, the organic electroluminescence device of the present invention is not limited to the top emission type and application to a TAC structure using the top emission type, and an organic layer having at least a light emitting layer is sandwiched between an anode and a cathode. The present invention can be widely applied to the configuration. Therefore, the cathode, organic layer, and anode are laminated in order from the substrate side, and the electrode located on the substrate side (the lower electrode as the cathode or anode) is made of a transparent material so that it is on the opposite side of the substrate. The present invention can also be applied to a so-called transmissive organic electroluminescent element in which light is extracted from the upper electrode side of the above. Even if it is such a structure, the same effect can be acquired by using the organic material demonstrated using General formula (1) and General formula (2) for an organic layer.

  Furthermore, the organic electroluminescent element of the present invention may be an element formed by a pair of electrodes (anode and cathode) and an organic layer sandwiched between the electrodes. For this reason, it is not limited to what comprised only a pair of electrode and organic layer, and other components (for example, an inorganic compound layer and an inorganic component) coexist in the range which does not impair the effect of this invention. Is not to be excluded.

  A synthesis example of the organic material of the present invention and an example of the organic electroluminescent element of the present invention using this organic material will be specifically described. Here, first, Synthesis Examples 1 to 3 of the organic material of the present invention will be described, and then a procedure for manufacturing an organic electroluminescent element using these organic materials and an organic electroluminescent element of a comparative example, and further The evaluation result will be described.

<Synthesis example 1 of organic material>
8-N, N-diphenylamino-3,3′-bifluoranthene represented by the structural formula (1) in Table 1 was synthesized by the following procedure.

  First, referring to the following reaction formula (1), a 100 ml three-necked flask equipped with a mechanical stirrer was sufficiently replaced with nitrogen, and then 3-iodofluoranthene (33 g, 100 mmol), 3-iodo-8-nitro. Fluoranthene (37 g, 100 mmol) and copper powder (1.3 g) were added, 5 ml of nitrobenzene was added as a solvent, and the reaction was carried out at 200 ° C. for 8 hours. After completion of the reaction, the reaction product was extracted with toluene and washed thoroughly with water. The toluene layer side was dried with sodium sulfate and then concentrated, and passed through a silica column with a mixed solvent of toluene / ethyl acetate to obtain compound (C1) in a yield of 45%.

  Subsequently, referring to the following reaction formula (2), a 500 ml three-necked flask equipped with a mechanical stirrer was sufficiently substituted with nitrogen, and then the compound (C1) synthesized above (17 g, 40 mmol) was added and 95% 100 ml of ethanol was poured. The mixture was heated to 50 ° C., 80 mg of palladium / activated carbon (Pd / C) was added, and stirring was started. Subsequently, 40 ml of hydrazine was dropped and reacted at the reflux temperature of ethanol for 6 hours. After completion of the reaction, ethanol was evaporated, and the reaction product was extracted with toluene and washed thoroughly with water. The toluene layer side was dried with sodium sulfate, concentrated, thoroughly washed with acetone, and passed through a silica column with a mixed solvent of toluene / ethyl acetate to obtain compound (C2) in a yield of 83%.

  Subsequently, referring to the following reaction formula (3), a 500 ml three-necked flask equipped with a mechanical stirrer was sufficiently substituted with nitrogen, and then the compound (C2) synthesized above (4.0 g, 10 mmol), bromobenzene (3.3 g, 21 mmol) was added sequentially and 100 mL of toluene was poured. While stirring, palladium acetate (120 mg, 0.5 mmol), tri (t-butyl) phosphine (420 mg, 2.1 mmol), and t-butoxy sodium (2.4 g, 25 mmol) were added and heating started. The reaction was carried out at reflux temperature for 8 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, the organic layer was separated, washed 5 times with water, and the organic layer was dried over magnesium sulfate. The solution was concentrated and passed through a silica column with a mixed solvent of hexane / toluene to obtain 3.1 g (yield 51%) of a yellow solid.

As a result of measuring the obtained solid by ¹ H-NMR, ¹³ C-NMR, and FD-MS, 8-N, N-diphenylamino-3,3′-bifluoranthene [Structural Formula (1), which is the target product, was obtained. It was confirmed that

<Synthesis Example 2 of Organic Material>
8,8′-bis (N, N-diphenylamino) -3,3′-bifluoranthene represented by the structural formula (5) in Table 1 was synthesized by the following procedure.

  First, referring to the following reaction formula (4), a coupling reaction was carried out only with 8-nitro-3-iodofluoranthene without adding 3-iodofluorene in the reaction formula (1) shown in Synthesis Example 1. The compound (C3) was obtained in 78% yield under the same conditions as shown in Synthesis Example 1.

  Further, the subsequent amination reaction of the nitro group and the subsequent diphenylamination reaction were carried out in the same manner as in Synthesis Example 1 to obtain 5.1 g of a yellow solid.

As a result of measuring the obtained solid by ¹ H-NMR, ¹³ C-NMR, and FD-MS, 8,8′-bis (N, N-diphenylamino) -3,3′-bifluoranthene, which is the target product, was obtained. It was confirmed that [Structural Formula (5)].

<Synthesis Example 3 of Organic Material>
3,3′-bis (N-2-naphthyl-N-phenylamino) -8,8′-bifluoranthene represented by the structural formula (28) in Table 1 was synthesized by the following procedure.

First, referring to the following reaction formula (5), a 1000 ml three-necked flask equipped with a mechanical stirrer was sufficiently replaced with nitrogen, and then 500 ml of DMF was poured as a solvent, followed by 1-bromo-5-hydroxynaphthalene. (11 g, 50 mmol), 3,3′-dibromo-4,4′-biphenyldiboronic acid (42 g, 105 mmol), tricyclohexylphosphine (hereinafter referred to as P (Cy) ₃ ) (14 g, 50 mmol), 1,8-diazabicyclo [5.4.0] undecene (hereinafter referred to as DBU) (60 ml), and bisdibenzylideneacetone palladium (hereinafter referred to as Pd ₂ (dba) ₃ ) (7.1 g, 12 0.5 mmol) was sequentially added to the solvent. The temperature of the reaction solution was raised to 150 ° C. and carried out for 48 hours while refluxing. After completion of the reaction, washing was performed twice with 10% hydrochloric acid. Subsequently, it was washed with water, and the organic layer was dried over sodium sulfate and then concentrated and passed through a silica column with a mixed solvent of hexane / toluene to obtain 13 g (yield 65%) of a white solid of compound (C4).

  Next, referring to the following reaction formula (6), a 500 ml three-necked flask equipped with a mechanical stirrer was sufficiently replaced with nitrogen, and then 100 ml of chloroform was poured as a solvent, followed by compound (C4) (9 g, 20 mmol), and 5 ml of pyridine were added. While cooling to 0 ° C. with ice cooling, 12 g of trifluoromethanesulfonic anhydride was slowly added dropwise. After the total amount was dropped, the reaction was carried out at 0 ° C. for 3 hours and further at room temperature for 2 hours. After completion of the reaction, the reaction mixture was washed with water, and the organic layer was dried over sodium sulfate and concentrated, and passed through a silica column with a toluene solvent to obtain 11 g (yield 80%) of a white solid of compound (C5).

  Subsequently, referring to the following reaction formula (7), a 300 ml three-necked flask equipped with a mechanical stirrer was sufficiently substituted with argon, and then 100 ml of THF was poured as a solvent. Subsequently, compound (C5) (7 g, 10 mmol), 2-naphthylphenylamine (5 g, 22 mmol), and palladium acetate (90 mg, 0.4 mmol), BINAP (370 mg, 0.6 mmol), and cesium carbonate (7.2 g, 22 mmol) as catalyst. The temperature was slowly raised to 70 ° C. The reaction was carried out at 70 ° C. for 30 hours. After completion of the reaction, it was washed with water, and the organic layer was dried over sodium sulfate and then concentrated, and passed through a silica column with a toluene / ethyl acetate mixed solvent to obtain 12 g (yield 81%) of a solid compound.

As a result of measuring the obtained solid compound by ¹ H-NMR, ¹³ C-NMR, and FD-MS, 3,3′-bis (N-2-naphthyl-N-phenylamino) -8, which is the target product, was obtained. It was confirmed to be 8′-bifluoranthene [Table 1 Structural Formula (28)].

<Example 1>
Using the 8-N, N-diphenylamino-3,3′-bifluoranthene [Structural Formula (1) in Table 1] obtained in Synthesis Example 1, an organic electroluminescent device (see FIG. 2) was prepared as follows. did.

First, a film (thickness: about 100 nm) made of chromium (Cr) is formed as the anode 13 on the substrate 12 made of a glass plate of 30 mm × 30 mm, and silicon dioxide (SiO ₂ ) is further evaporated to form 2 mm × A cell for an organic electroluminescent element masked with an insulating film other than the light emitting region of 2 mm was produced.

Next, as a hole injection layer 14a of the organic layer 14, a film made of m-MTDATA represented by the following structural formula (31) is formed to a thickness of 30 nm (deposition rate: 0.2 to 0.4 nm / sec). However, m-MTDATA is 4,4 ′, 4 ″ -tris (phenyl-m-tolylamino) triphenylamine.

Next, as the hole transport layer 14b, a film made of α-NPD represented by the following structural formula (32) was formed with a film thickness of 30 nm (deposition rate: 0.2 to 0.4 nm / sec). However, α-NPD is N, N′-bis (1-naphthyl) -N, N′-diphenyl [1,1′-biphenyl] -4,4′-diamine.

  On the hole injection layer 14a and the hole transport layer 14b thus formed, 8-N, N-diphenylamino-3,3′-bifluoranthene obtained by Synthesis Example 1 above as the light emitting layer 14c [ Structural formula (1)] in Table 1 was deposited with a film thickness of 20 nm.

Next, as the electron transport layer 14d, Alq3 (8-hydroxyquinoline aluminum) represented by the following structural formula (33) was deposited with a thickness of 20 nm.

As described above, after forming the organic layer 14 formed by sequentially laminating the hole injection layer 14a, the hole transport layer 14b, the light emitting layer 14c, and the electron transport layer 14d, as the first layer 15a of the cathode 15, A film made of Li ₂ O was formed with a film thickness of about 0.3 nm (deposition rate: 0.01 nm / sec.) By vacuum evaporation.

  Finally, a 10 nm-thick MgAg film was formed as the second layer 15b of the cathode 15 on the second layer 15a by a vacuum deposition method.

When the organic electroluminescence device produced in this way was driven by DC voltage, green coloration was confirmed as shown in Table 7 below, and the light emission luminance was 340 cd / m ² at a driving voltage of 5V. Further, when this light-emitting element was driven at a constant current at an initial luminance of 300 cd / m ² , the light emission lifetime (luminance half-life) was 900 hours.

<Examples 2 and 3>
An organic electroluminescence device was produced in the same manner as in Example 1 except that the compounds of the structural formulas shown in Table 7 were used as the organic material of the light emitting layer 14c described in Example 1, and the same evaluation was performed. went. In Table 7, the evaluation results are also shown.

<Comparative Example 1>
Except for using 3-N, N-diphenylaminofluoranthene (see JP-A-10-125467) represented by the following structural formula (34) as the organic material of the hole transport layer 14b described in Example 1, An organic electroluminescent device was produced in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 7 above.

  From the results shown in Table 7 above, the organic electroluminescent elements of Examples 1 to 3 in which the light emitting layer 14c in the organic layer 14 is configured using the organic material of the present invention use the compound of the structural formula (34). Compared with the organic electroluminescent element of Comparative Example 1 in which the light emitting layer 14c in the organic layer 14 is configured, the light emission luminance is improved by driving at a constant voltage (5 V), and the light emission lifetime is also greatly improved. It was confirmed.

<Example 4>
As the light-emitting layer 14c described in Example 1, 9,10-di (2-naphthyl) anthracene (ADN) represented by the following structural formula (35) was deposited to form a film having a thickness of 50 nm. At that time, 8-N, N-diphenylamino-3,3′-bifluoranthene [Structural Formula (1) in Table 1] produced in Synthesis Example 1 was used as the ADN and the relative film thickness ratio (ie, volume ratio) was 8 volumes. The light emitting layer 14c was obtained by doping with%.

Subsequently, Alq3 was vapor-deposited with a film thickness of 20 nm as the electron transport layer 14d. When the organic electroluminescence device produced in this way was driven by a direct current voltage, green color was confirmed, and the light emission luminance was 1000 cd / m ² at a driving voltage of 5V. Further, when this organic electroluminescence device was driven at a constant current at an initial luminance of 300 cd / m ² , the light emission lifetime (luminance half-life) was as shown in Table 8 below.

<Examples 5-7>
Except for changing the doping concentration of 8-N, N-diphenylamino-3,3′-bifluoranthene [Structural Formula (1) in Table 1] to ADN in Example 4 to the concentration described in Table 8 above, Evaluation was made as an element configuration similar to Example 4. The results are shown in Table 8 above.

  From the results shown in Table 8 above, when the light emitting layer 14c is doped with the organic material of the present invention, the light emission luminance (light emission efficiency) is kept high and more excellent light emission in the range of 30% by volume or less. It was confirmed that the lifetime was obtained.

It is sectional drawing which shows one structure of an organic electroluminescent element. It is sectional drawing which shows the structure of the organic electroluminescent element in embodiment to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Organic electroluminescent element, 13 ... Anode, 14 ... Organic layer, 15 ... Cathode, 14b ... Hole transport layer, 14c ... Light emitting layer, 14d ... Electron transport layer

Claims (9)

An organic material for an organic electroluminescent element represented by the following general formula (1).

However, in the general formula (1), A ^{1 to} A ²⁰ are each independently hydrogen, halogen, hydroxyl group, substituted or unsubstituted carbonyl group having 20 or less carbon atoms, substituted or unsubstituted group having 20 or less carbon atoms. Carbonyl ester group, substituted or unsubstituted alkyl group having 20 or less carbon atoms, substituted or unsubstituted alkenyl group having 20 or less carbon atoms, substituted or unsubstituted alkoxyl group having 20 or less carbon atoms, substituted or unsubstituted 30 carbon atoms or less An unsubstituted aryl group, a substituted or unsubstituted heterocyclic group having 30 or less carbon atoms, a cyano group, a nitro group, or a silyl group, and at least one of A ^{1 to} A ²⁰ is represented by the following general formula (2) or The substituent shown by General formula (3) is shown.

However, Ar ^a and Ar ^b in the general formula (2) each independently represent a substituted or unsubstituted aryl group having 30 or less carbon atoms, and Ar ^c , Ar ^d , and Ar ^e in the general formula (3) are And each independently represents a substituted or unsubstituted aryl group having 30 or less carbon atoms. The organic material according to claim 1,
In the general formula (1), at least one of A ^{1 to} A ⁴ and A ^{15 to} A ²⁰ and at least one of A ^{5 to} A ¹⁴ are the general formula (2) or the general formula (3). An organic material characterized by showing a substituent of The organic material according to claim 1,
One of A ¹ , A ² , A ¹⁹ , and A ^{20 in} the general formula (1) and one of A ^{7 to} A ¹⁰ are represented by the general formula (2) or the general formula (3). An organic material characterized by showing a substituent. In an organic electroluminescent element formed by sandwiching an organic layer between an anode and a cathode,
The organic layer is configured using an organic material represented by the following general formula (1).

However, in the general formula (1), A ^{1 to} A ²⁰ are each independently hydrogen, halogen, hydroxyl group, substituted or unsubstituted carbonyl group having 20 or less carbon atoms, substituted or unsubstituted group having 20 or less carbon atoms. Carbonyl ester group, substituted or unsubstituted alkyl group having 20 or less carbon atoms, substituted or unsubstituted alkenyl group having 20 or less carbon atoms, substituted or unsubstituted alkoxyl group having 20 or less carbon atoms, substituted or unsubstituted 30 carbon atoms or less An unsubstituted aryl group, a substituted or unsubstituted heterocyclic group having 30 or less carbon atoms, a cyano group, a nitro group, or a silyl group, and at least one of A ^{1 to} A ²⁰ is represented by the following general formula (2) or The substituent shown by General formula (3) is shown.

However, Ar ^a and Ar ^b in the general formula (2) each independently represent a substituted or unsubstituted aryl group having 30 or less carbon atoms, and Ar ^c , Ar ^d , and Ar ^e in the general formula (3) are And each independently represents a substituted or unsubstituted aryl group having 30 or less carbon atoms. The organic electroluminescent device according to claim 4, wherein
In the general formula (1), at least one of A ^{1 to} A ⁴ and A ^{15 to} A ²⁰ and at least one of A ^{5 to} A ¹⁴ are the general formula (2) or the general formula (3). The organic electroluminescent element characterized by showing the substituent of these. The organic electroluminescent device according to claim 4, wherein
One of A ¹ , A ² , A ¹⁹ , and A ^{20 in} the general formula (1) and one of A ^{7 to} A ¹⁰ are represented by the general formula (2) or the general formula (3). An organic electroluminescent element characterized by showing a substituent. The organic electroluminescent device according to claim 4, wherein
The organic layer is provided with a hole transport layer configured using the organic material represented by the general formula (1) and the general formula (2). The organic electroluminescent device according to claim 4, wherein
The organic layer is provided with a light emitting layer configured using the organic material represented by the general formula (1) and the general formula (2). The organic electroluminescent device according to claim 8, wherein
An organic electroluminescent element, wherein the light emitting layer contains the organic material represented by the general formula (1) and the general formula (2) at a ratio of 30% by volume or less.

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