JP2016048767A - Compound for organic electroluminescent element, and organic electroluminescent element arranged by use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compound for an organic electroluminescent element, which enables the achievement of a high light emission efficiency; and an organic electroluminescent element arranged by use of such a compound.SOLUTION: A compound for an organic electroluminescent element is expressed by the general formula (1). (In the formula (1), Arrepresents a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon ring group; and Arrepresents a substituted or unsubstituted aromatic hydrocarbon ring group. In the general formula (1), at least three naphthalene rings are included.)SELECTED DRAWING: Figure 1

Description

  The present invention relates to a compound for an organic electroluminescent device and an organic electroluminescent device using the same.

  When organic electroluminescent elements are classified according to their light emission principles, they can be classified into two types, fluorescent and phosphorescent types. In general, an organic electroluminescent element is composed of a light emitting layer and a pair of counter electrodes sandwiching the layer. When an electric field is applied between both electrodes, holes are injected from the hole injection electrode (anode) side, and electrons are injected from the electron injection electrode (cathode) side. At this time, singlet excitons and triplet excitons are generated at a ratio of 1: 3 according to the spin statistical rule. Since the fluorescent organic electroluminescent element uses light emission by singlet excitons, the theoretical limit value of the internal quantum efficiency is 25%, and high efficiency is a problem.

  Compounds with anthracene structure are known to be excellent as materials for organic electroluminescence devices with high efficiency and long life, and active research and development for improving properties are particularly active as materials for fluorescent organic electroluminescence devices. Has been done. Patent Document 1 discloses a compound for an organic electroluminescence device having a dianthracene structure and high emission efficiency and reliability. Patent Documents 2 to 4 disclose asymmetric anthracene derivatives as high-efficiency, long-life organic electroluminescent element compounds.

  In addition, as a technology for improving the efficiency of a fluorescence type device, a method using a singlet exciton generation phenomenon (triplet-triplet annealing = TTA) caused by collision of triplet excitons is known (for example, non-existing). Patent Document 1). According to this method, in addition to singlet excitons generated by charge recombination, light emitted when singlet excitons generated by collision of triplet excitons return to the ground state is used. This makes it possible to increase the efficiency of the fluorescent organic electroluminescent device. In order to obtain high light emission efficiency in an organic electroluminescent device that emits fluorescence, it is preferable to efficiently generate light emission by TTA.

  In Patent Documents 5 and 6, for an organic electroluminescent device using an anthracene-based compound as a host material, the device configuration is adjusted based on the excitation lowest triplet (T1) energy of the device constituent material, and the TTA phenomenon occurs inside the light emitting layer. A high efficiency technique by efficiently causing the problem is disclosed.

  In Non-Patent Document 2, an organic electroluminescence device using an anthracene compound alone as a light emitting layer material is analyzed, and an organic electroluminescence device using an anthracene compound having high anisotropy has high TTA efficiency and luminous efficiency. Is disclosed.

JP 2006-193528 A International Publication No. 2004/018857 International Publication No. 2005/054162 International Publication No. 2005/061656 International Publication No. 2010/134342 JP 2013-157552 A

Journal of Applied Physics, 102, 114504 (2007) Applied Physics Letters, 99, 123303 (2011)

  However, even if the structure of the organic electroluminescent element material is improved or the TTA utilization technique is used, the luminous efficiency of the fluorescent organic electroluminescent element is still insufficient, and further improvement of the luminous efficiency is required.

  An object of the present invention is to provide a compound for an organic electroluminescence device that can provide sufficiently high luminous efficiency when used as a constituent material of the organic electroluminescence device, and an organic electroluminescence device using the compound.

  In order to achieve the above object, the present invention provides a compound for an organic electroluminescent device represented by the following general formula (1).

（式中、Ａｒ^１は水素原子、または置換もしくは無置換の芳香族炭化水素環基、Ａｒ^２は、置換もしくは無置換の芳香族炭化水素環基である。
一般式（１）において、少なくとも３個のナフタレン環が含まれる。）

(In the formula, Ar ¹ is a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon ring group, and Ar ² is a substituted or unsubstituted aromatic hydrocarbon ring group.
In the general formula (1), at least three naphthalene rings are included. )

  In TTA, two triplet excitons collide to generate one singlet exciton having an energy equivalent to twice the T1 energy, so that the converted singlet energy can be received. A molecule having a singlet energy level corresponding to twice the energy is considered to have a high probability of TTA. In the anthracene derivative having a naphthalene ring in the molecule, a singlet energy level corresponding to twice the T1 energy is formed. Since the compound represented by the general formula (1) of the present invention has three or more naphthalene rings in the anthracene molecule, there are a plurality of singlet energy levels corresponding to twice the T1 energy. As a result, the compound represented by the general formula (1) of the present invention realizes an organic electroluminescent device exhibiting high luminous efficiency in order to exhibit high TTA efficiency when used as a constituent material of the organic electroluminescent device. can do.

  Moreover, it is preferable that the compound for organic electroluminescent elements concerning this invention is a compound represented by General formula (1) containing at least 4 naphthalene ring.

  Such a compound for an organic electroluminescent element contains four naphthalene rings, so that it has twice the T1 energy as compared with the organic electroluminescent element represented by the general formula (1) containing three naphthalene rings. Since there are more corresponding singlet energy levels, it is possible to realize an organic electroluminescent device that exhibits higher TTA efficiency and higher luminous efficiency.

  Moreover, it is preferable that the compound for organic electroluminescent elements concerning this invention is a compound represented by following General formula (2).

（式中、Ａｒ^３は置換もしくは無置換の芳香族炭化水素環基である。
一般式（２）において、少なくとも４個のナフタレン環が含まれる。）

(In the formula, Ar ³ is a substituted or unsubstituted aromatic hydrocarbon ring group.
In general formula (2), at least 4 naphthalene rings are included. )

  Since the compound represented by the general formula (2) of the present invention contains at least four naphthalene rings in the anthracene molecule, an organic electroluminescence device exhibiting high TTA efficiency and high luminous efficiency can be realized. It becomes possible. In addition, since the compound represented by the general formula (2) has a symmetric structure, it can be easily synthesized and purified as compared with a compound having an asymmetric structure. Therefore, a high-purity material can be easily obtained, and when used as a constituent material for an organic electroluminescent element, a highly efficient organic electroluminescent element can be realized.

  In the organic electroluminescence device in which at least one organic layer is sandwiched between a pair of electrodes composed of an anode and a cathode, at least one of the organic layers is represented by the general formula (1) or the general formula. It is preferable that the organic electroluminescent element is characterized by containing the compound represented by (2) alone or as a component of a mixture.

  According to such an organic electroluminescent element, since the compound for an organic electroluminescent element of the present invention is included, high luminous efficiency can be obtained.

  ADVANTAGE OF THE INVENTION When using as a constituent material of an organic electroluminescent element according to this invention, the organic electroluminescent element compound which can obtain high luminous efficiency, and an organic electroluminescent element using this compound can be provided.

It is a schematic cross section which shows an example of the organic electroluminescent element concerning this embodiment. It is a figure which shows an example of the transient response measurement result of the organic electroluminescent element concerning this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

(Compound for organic electroluminescence device)
The compound for organic electroluminescent elements according to a preferred embodiment of the present invention is an anthracene compound having a specific structure represented by the following general formula (1).

（式中、Ａｒ^１は水素原子、または置換もしくは無置換の芳香族炭化水素環基、Ａｒ^２は、置換もしくは無置換の芳香族炭化水素環基である。
一般式（１）において、少なくとも３個のナフタレン環が含まれる。）

(In the formula, Ar ¹ is a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon ring group, and Ar ² is a substituted or unsubstituted aromatic hydrocarbon ring group.
In the general formula (1), at least three naphthalene rings are included. )

  Conventional techniques for improving TTA efficiency are limited to methods that utilize device characteristics optimization and physical properties of host materials. The TTA efficiency greatly depends on the electronic characteristics of the host material that occupies the main component of the light emitting layer of the organic electroluminescent element. Therefore, the present inventors have focused on the electronic characteristics of the host material, and have studied to increase the efficiency of the organic electroluminescent device by improving the TTA efficiency of the host material itself.

  In TTA, two triplet excitons collide to generate one singlet exciton having energy equivalent to twice the T1 energy. That is, a molecule that can receive singlet energy converted from triplet energy and has a singlet energy level corresponding to twice the T1 energy is considered to have a high probability of TTA. The design of molecules with positions was carried out.

  Anthracene compounds in which the naphthalene ring is not substituted in the molecule do not have a singlet energy level corresponding to twice the T1 energy. As a result of intensive studies, the present inventors have found that a singlet energy level corresponding to twice the T1 energy is formed by introducing a naphthalene ring into an anthracene molecule. For this reason, the anthracene derivative which has a naphthalene ring shows high TTA efficiency, and it becomes possible to implement | achieve the highly efficient organic electroluminescent element.

  In addition, when there are a plurality of naphthalene rings in the anthracene molecule, a plurality of singlet levels having energy equivalent to twice the T1 energy are formed, so that the probability of TTA generation is increased and higher TTA efficiency is exhibited. Thus, it becomes possible to realize an organic electroluminescent element exhibiting higher luminous efficiency. This effect is more pronounced when three or more naphthalene rings are present in the anthracene molecule.

  Patent Document 4 discloses an asymmetric anthracene derivative having a highly efficient and long-lasting naphthalene ring, but the 9-position of the anthracene ring is substituted at the 2- or 4-position of naphthalene having a substituent at the 6-position. Only compounds in which the 1-position of naphthalene having a group is substituted are disclosed. The compound represented by the general formula (1) of the present invention is a compound in which the 9-position of the anthracene ring is substituted with the 2-position of naphthalene having a substituted or unsubstituted aromatic hydrocarbon ring group at the 7-position. Since the anthracene compound having such a structure has higher molecular flexibility than the compound described in Patent Document 4, the crystallinity of the thin film is low and a stable amorphous film can be formed. For this reason, when used as a constituent material of an organic electroluminescent element, it is possible to realize an organic electroluminescent element having high stability.

In the general formula (1), Ar ¹ is a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon ring group, and Ar ² is a substituted or unsubstituted aromatic hydrocarbon ring group.
As this aromatic hydrocarbon ring group, those having a nuclear carbon number of 5 to 40 are preferable. Specifically, a phenyl group, a naphthyl group, a phenanthryl group, a pyrenyl group, a fluorenyl group, a benzofluorenyl group, a dibenzofluorene group. Nyl group, o-, m- or p-biphenylyl group, anthryl group and the like can be mentioned.
Among these, a phenyl group, a naphthyl group, a phenanthryl group, and a fluorenyl group are more preferable from the viewpoint of ease of synthesis.

The aromatic hydrogen ring group may be further substituted with a substituent. Examples of such a substituent include an aromatic hydrocarbon ring group, a heterocyclic group, an alkyl group, an alkoxy group, an aryloxy group, a halogeno group. Group, silyl group and the like. There may be a plurality of these substituents, and adjacent ones may form a saturated or unsaturated cyclic structure.
Among these substituents, an aromatic hydrocarbon ring group having 5 to 40 nuclear carbon atoms is more preferable. Specifically, a phenyl group, a naphthyl group, a phenanthryl group, a pyrenyl group, a fluorenyl group, a benzofluorenyl group, A dibenzofluorenyl group, o-, m- or p-biphenylyl group, anthryl group and the like can be mentioned.

  Moreover, it is preferable that the compound for organic electroluminescent elements concerning this embodiment is a compound for organic electroluminescent elements represented by General formula (1) containing at least 4 naphthalene rings.

  Such a compound for an organic electroluminescent element contains four naphthalene rings, so that it has twice the T1 energy as compared with the organic electroluminescent element represented by the general formula (1) containing three naphthalene rings. Since there are more corresponding singlet energy levels, it is possible to realize an organic electroluminescent device that exhibits higher TTA efficiency and higher luminous efficiency.

  Moreover, the compound for organic electroluminescent elements concerning this embodiment has a preferable compound represented by following General formula (2).

（式中、Ａｒ^３は置換もしくは無置換の芳香族炭化水素環基である。
一般式（２）において、少なくとも４個のナフタレン環が含まれる。）

(In the formula, Ar ³ is a substituted or unsubstituted aromatic hydrocarbon ring group.
In general formula (2), at least 4 naphthalene rings are included. )

  Since the compound represented by the general formula (2) contains at least four naphthalene rings in the anthracene molecule, an organic electroluminescence device exhibiting high TTA efficiency and high light emission efficiency can be realized.

  Further, the compound represented by the general formula (2) has a large molecular bend, and the 2-position of naphthalene having a substituted or unsubstituted aromatic hydrocarbon ring group at the 7-position is substituted at the 9-position of the anthracene ring. A compound. Therefore, even with a symmetric structure, the crystallinity of the thin film is low, and a stable amorphous film can be formed. When used as a constituent material of an organic electroluminescent element, a highly stable organic electroluminescent element is realized. Is possible.

  Furthermore, since the compound represented by the general formula (2) has a symmetric structure, the synthesis route is simple and purification is easy as compared with a compound having an asymmetric structure. Therefore, a high-purity material can be easily obtained, and when used as a constituent material for an organic electroluminescent element, a highly efficient organic electroluminescent element can be realized.

In the general formula (2), Ar ³ is a substituted or unsubstituted aromatic hydrocarbon ring group.
As this aromatic hydrocarbon ring group, those having a nuclear carbon number of 5 to 40 are preferable. Specifically, a phenyl group, a naphthyl group, a phenanthryl group, a pyrenyl group, a fluorenyl group, a benzofluorenyl group, a dibenzofluorene group. Nyl group, o-, m- or p-biphenylyl group, anthryl group and the like can be mentioned.
Among these, a phenyl group, a naphthyl group, a phenanthryl group, and a fluorenyl group are more preferable from the viewpoint of ease of synthesis.

The aromatic hydrocarbon ring group may be further substituted with a substituent. Examples of such a substituent include an aromatic hydrocarbon ring group, a heterocyclic group, an alkyl group, an alkoxy group, an aryloxy group, Examples thereof include a halogeno group and a silyl group. There may be a plurality of these substituents, and adjacent ones may form a saturated or unsaturated cyclic structure.
Among these substituents, an aromatic hydrocarbon ring group having 5 to 40 nuclear carbon atoms is more preferable. Specifically, a phenyl group, a naphthyl group, a phenanthryl group, a pyrenyl group, a fluorenyl group, a benzofluorenyl group, A dibenzofluorenyl group, o-, m- or p-biphenylyl group, anthryl group and the like can be mentioned.

  There is no particular limitation on the molecular weight of the compound of the present embodiment, but it is preferable that the molecular weight is 1000 or less in consideration of the device preparation process. This is because a compound having a molecular weight of 1000 or more is difficult to synthesize due to a decrease in solubility, and it is difficult to produce an organic electroluminescent element by a coating process. In addition, even when an organic electroluminescent element is produced by a vapor deposition process, the vapor deposition temperature becomes a high temperature of 400 ° C. or more, which may cause decomposition of the material. Therefore, the number of naphthalene rings contained in the compounds represented by the general formula (1) and the general formula (2) of the present invention is preferably 6 or less.

(Specific examples of compounds for organic electroluminescence devices)
As a suitable example of the compound for organic electroluminescent elements of this embodiment, following formula (I-1)-(I-33), (II-1)-(II-27), (III-1)-( And a compound represented by III-28).

(Organic electroluminescence device)
FIG. 1 is a schematic cross-sectional view showing an example of an organic electroluminescent element according to this embodiment. The organic electroluminescent element 1 shown in FIG. 1 includes a hole injection layer 4, a hole transport layer 5, a light emitting layer 6, and two electrodes (first electrode 3 and second electrode 9) arranged to face each other. The electron transport layer 7 and the electron injection layer 8 are sandwiched. The hole injection layer 4, the hole transport layer 5, the light emitting layer 6, the electron transport layer 7, and the electron injection layer 8 are all organic layers, and are stacked in this order from the first electrode 3 side. The electron injection layer 8 may be an inorganic layer (metal layer, metal compound layer, etc.).

  In the present embodiment, the first electrode 3 is formed on the substrate 2, but the order of stacking from the substrate 2 side may be reversed. That is, even if the second electrode 9, the electron injection layer 8, the electron transport layer 7, the light emitting layer 6, the hole transport layer 5, the hole injection layer 4, and the first electrode 3 are stacked in this order from the substrate 2 side. Good.

  Moreover, the compound for organic electroluminescent elements of the present invention may be contained in any of the layers described above, but is desirably contained in the light emitting layer 6.

  In the present embodiment, the first electrode 3 and the second electrode 9 function as a hole injecting electrode (anode) and an electron injecting electrode (cathode), respectively. Then, holes are injected from the second electrode 9 and electrons are injected from the second electrode 9, and the compound for organic electroluminescence element in the light emitting layer emits light by recombination thereof.

  The preferred thicknesses of the hole injection layer 4, the hole transport layer 5, the light emitting layer 6, the electron transport layer 7 and the electron injection layer 8 are all 1 to 200 nm.

(substrate)
The substrate 2 can be used without particular limitation as long as it is provided in a conventional organic electroluminescence device, and is an amorphous substrate such as glass or quartz, Si, GaAs, ZnSe, ZnS, GaP. A crystal substrate such as InP or a metal substrate such as Mo, Al, Pt, Ir, Au, Pd, or SUS can be used. Further, a thin film made of a crystalline or amorphous ceramic, metal, organic substance or the like formed on a predetermined substrate may be used.

  When the side of the substrate 2 is the light extraction side, it is preferable to use a transparent substrate such as glass or quartz as the substrate 2, and it is particularly preferable to use an inexpensive glass transparent substrate. The transparent substrate may be provided with a color filter film, a color conversion film containing a fluorescent material, a dielectric reflection film, or the like for adjusting the emission color.

(First electrode)
The first electrode 3 functions as a hole injection electrode (anode). Therefore, the material of the first electrode 3 can be used without particular limitation as long as it is provided in the conventional organic electroluminescent element, but it can be used efficiently and uniformly for the first electrode 3. A material capable of applying an electric field to is preferable.

  Further, when the substrate 2 side is the light extraction side, the transmittance at a wavelength of 400 nm to 700 nm, which is the emission wavelength region of the organic electroluminescent element, in particular, the transmittance of the first electrode 1 at the wavelength of each RGB color is 50%. Preferably, it is 80% or more, more preferably 90% or more. When the transmittance of the first electrode 3 is less than 50%, the light emission from the light emitting layer 6 is attenuated, and the luminance necessary for image display cannot be obtained.

The 1st electrode 3 with high light transmittance can be comprised using the transparent conductive film comprised with various oxides. As such a material, indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), and the like are preferable. It is particularly preferable in that a thin film having a uniform in-plane specific resistance can be easily obtained.

  The film thickness of the first electrode 3 is preferably determined in consideration of the above-described light transmittance. For example, when using an oxide transparent electrode, the film thickness is preferably 10 to 500 nm, more preferably 30 to 300 nm. When the film thickness of the first electrode 3 exceeds 500 nm, the light transmittance becomes insufficient and the first electrode 3 may be peeled off from the substrate 2 in some cases. In addition, the light transmittance is improved as the film thickness is decreased. However, when the film thickness is less than 10 nm, the resistance increases and the driving voltage of the organic electroluminescent element tends to increase.

(Second electrode)
The second electrode 9 functions as an electron injection electrode (cathode). The material of the second electrode 9 can be used without particular limitation as long as it is provided in a conventional organic electroluminescent device, and examples thereof include metal materials, organometallic complexes, and metal compounds. In order to efficiently and reliably inject electrons into the light emitting layer 6, it is preferable to use a material having a relatively low work function, and it may be transparent.

  Specific examples of the metal material constituting the second electrode 9 include alkali metals such as Li, Na, K or Cs, alkaline earth metals such as Mg, Ca, Sr or Ba, or Al (aluminum). . Alternatively, a metal having properties similar to those of an alkali metal or alkaline earth metal such as La, Ce, Sn, Zn, or Zr can be used. Furthermore, oxides or halides of the above metal materials can also be used. Further, it may be a mixture or alloy containing the above materials, and a plurality of these may be laminated.

  The film thickness of the second electrode 9 may be such that electrons can be uniformly injected, and may be 0.1 nm or more.

  An auxiliary electrode may be provided on the second electrode 9. Thereby, the electron injection efficiency to the light emitting layer 6 can be improved, and the penetration | invasion of the water | moisture content or the organic solvent to the electron injection layer 8, the electron carrying layer 7, and the light emitting layer 6 can be prevented. As a material for the auxiliary electrode, a general metal can be used because there is no restriction on work function and charge injection capability. However, it is preferable to use a metal having high conductivity and easy handling. In particular, when the second electrode 9 includes an organic material, it is preferable to select appropriately according to the type and adhesion of the organic material.

  Examples of the material used for the auxiliary electrode include Al, Ag, In, Ti, Cu, Au, Mo, W, Pt, Pd, and Ni. Among them, by using a low-resistance metal such as Al and Ag. Electron injection efficiency can be further increased. Further, by using a metal compound such as TiN, higher sealing properties can be obtained. These materials may be used alone or in combination of two or more. Moreover, when using 2 or more types of metals, you may use as an alloy. Such an auxiliary electrode can be formed by, for example, a vacuum deposition method or the like.

(Hole injection layer)
The hole injection layer 4 is a layer containing a compound having a function of facilitating the injection of holes from the first electrode 3. Specifically, it can be formed using at least one kind of arylamine, phthalocyanine, polyaniline / organic acid, polythiophene / polymer acid and the like.

(Hall transport layer)
The hole transport layer 5 is a layer containing a compound having a function of transporting injected holes (holes) to the light emitting layer 6 and a function of preventing electrons in the light emitting layer 6 from being injected into the hole transport layer 5. It is. The hole transport layer 5 uses at least one kind of hydrocarbon compound such as triarylmethane derivative, triarylamine derivative, stilbene derivative, polysilane derivative, polyphenylene vinylene and derivative thereof, polythiophene and derivative thereof, carbazole derivative, or anthracene derivative. Can be formed.

  In addition, if it is a material which has the function of the hole injection layer 4 and the hole transport layer 5 as a hole injection transport layer, it can fulfill the function for two layers by a single layer. On the other hand, the hole injection layer 4 and the hole transport layer 5 can be further functionally separated into a plurality of layers.

(Light emitting layer)
The light emitting layer 6 is a layer containing a compound having a function of transporting injected holes and electrons and a function of generating excitons by recombination of holes and holes. The compounds represented by the general formulas (1) and (2) of the present invention are preferably used for the light emitting layer 6. An organic electroluminescent device including the light emitting layer 6 containing such a material exhibits a high TTA efficiency as compared with a conventional organic electroluminescent device, and thus can obtain a sufficiently high luminous efficiency. In addition, since the compounds represented by the general formulas (1) and (2) of the present invention have high molecular flexibility, the thin film has low crystallinity and can form a stable amorphous film. For this reason, when used as a constituent material of an organic electroluminescent element, it is possible to realize an organic electroluminescent element having high stability.

  The light emitting layer 6 may use the compound represented by General formula (1) and General formula (2) independently as a constituent material, and the compound represented by General formula (1) and General formula (2) is used. Furthermore, you may contain 1 type (s) or 2 or more types used as the material of the conventional light emitting layer. Moreover, the laminated structure of the compound represented by General formula (1) and General formula (2) and another material may be sufficient.

  The light emitting layer 6 may contain other fluorescent substances as a light emitting doping material in addition to the host material. Examples of the fluorescent substance include compounds such as quinacridone, rubrene, and styryl dyes, metal complex compounds having 8-quinolinol or a derivative thereof such as tris (8-quinolinolato) aluminum as a ligand, anthracene derivatives, fluoranthene derivatives, Examples include pyrene derivatives, perylene derivatives, fluorene derivatives, tetraarylethene derivatives, and aromatic amine derivatives. Although suitable content of dopant material changes with combinations of host material and dopant material, it is preferable that it is 0.1-30 mass% on the basis of the whole constituent material of a light emitting layer, and it is 1-10 mass% Is more preferable.

  The light emitting layer 6 may contain other compounds of the host material and the light emitting doping material. By mixing other compounds, carrier transport can be adjusted, and by mixing fluorescent dyes, the emission color can be converted and used. Examples of the compound for adjusting carrier transport include metal complex compounds having 8-quinolinol or a derivative thereof such as tris (8-quinolinolato) aluminum as a ligand, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, imidazopyridine derivatives, Electron transporting compounds such as imidazopyrimidine derivatives and phenanthroline derivatives, hole transporting compounds such as triarylamine derivatives, and the like can be preferably used. The compounds represented by the general formula (1) and the general formula (2) of the present invention have low crystallinity and can form a stable thin film mixed layer with an electron transporting compound or a hole transporting compound. When used as a constituent material of an electroluminescent element, an organic electroluminescent element with high stability can be realized.

(Electron transport layer)
The electron transport layer 7 has a function of transporting injected electrons and a function of preventing holes from being injected into the electron transport layer 7 from the light emitting layer 6. The compounds represented by the general formula (1) and the general formula (2) of the present invention can be used as the electron transport layer 7, and particularly represented by the general formula (1) and the general formula (2) in the light emitting layer. When a compound is used, it is preferable to use the same material as the light-emitting layer for the electron-transporting layer because electron injection efficiency into the light-emitting layer is good.

(Electron injection layer)
The electron injection layer 8 has a function of facilitating injection of electrons from the second electrode 9 and a function of improving adhesion with the second electrode 9. The electron injection layer 8 is composed of a metal complex, an oxadiazole derivative, a triazole derivative, a triazine derivative, a quinoline derivative, a quinoxaline derivative, diphenylquinone having an 8-quinolinol or its derivative such as tris (8-quinolinolato) aluminum as a ligand. Derivatives, nitro-substituted fluorenone derivatives, thiopyrandioxide derivatives, pyridine derivatives, pyrimidine derivatives, imidazopyridine derivatives, imidazopyrimidine derivatives, phenanthroline derivatives, and the like can be used.

  The organic electroluminescence device 1 according to this embodiment can be produced by a known method except that the light emitting layer 6 and the electron transport layer 7 contain the compound for organic electroluminescence device of the present invention. As a method for forming each organic layer including the light emitting layer 6 and the electron transport layer 7, a vacuum vapor deposition method, an ionization vapor deposition method, a coating method, or the like is appropriately selected according to the material constituting the organic layer. Can be adopted.

  Specific examples of the coating method include spin coating methods, various printing methods such as gravure printing, and ink jet methods. Examples of the solvent used in this coating method include hydrocarbon solvents such as toluene and xylene, and halogen solvents such as dichloroethane. The compounds represented by the general formula (1) and the general formula (2) of the present invention have high molecular flexibility, and thus have high solubility, and can be sufficiently formed even by a coating process. In the case of the spin coating method, a thin film of about 50 nm to 200 nm can be formed by using a solution having a concentration of about 1 to 3%.

(Evaluation of ratio of light emission derived from TTA)
The ratio of light emission derived from TTA to the total light emission of the organic light-emitting element is obtained by performing transient response measurement and analyzing the measurement result.

  Transient response measurement is a pulse current generator that applies a rectangular wave current to an organic light emitting device, detects the light emission intensity from the organic light emitting device in synchronization with the current, and measures the time-resolved measurement with an oscilloscope. By doing.

  Specifically, for example, first, a desired current density is applied to the organic light emitting element for a sufficient time until the light emission intensity reaches a steady state. Thereafter, the current density is set to zero, and the current application is stopped.

  FIG. 2 is an example of a transient response measurement result of the organic electroluminescence device according to the present embodiment, and shows a temporal change in the emission intensity obtained in synchronization with the application of the current density. The current density is switched from positive current to zero at 0 s, and the light emission intensity in a steady state when positive current is applied is 1.

  The breakdown of the emission intensity when a positive current is applied is the sum of the emission from singlet excitons generated by charge recombination and the emission from singlet excitons generated by TTA.

  On the other hand, when the current density is set to zero and the current application is stopped, light emission by TTA is observed. The observed luminescence can be observed as a transient response characteristic. By analyzing the transient response characteristics of light emission by TTA, the ratio of light emission derived from TTA to the total light emission is determined.

  If the transient response characteristic of light emission when the current density is zero and the application of current is stopped is based on TTA, the light emission attenuation can be expressed by a two-component attenuation curve.

  Therefore, as shown in FIG. 2, the transient response characteristic is fitted by Equation 1 to obtain the light emission ratio A by TTA. In Equation 1, L is the light emission intensity when the current density is zero and the application of current is stopped, A is the light emission ratio by TTA, t is time, Ts is the lifetime of light emission from singlet excitons, and TTTA is TTA Indicates the lifetime of light emission.

L = (1−A) exp (−t / Ts) + Aexp (−t / TTTA) (Formula 1)

  At this time, A at time t = 0 when the current density is switched from the positive current density to zero is the ratio of light emission by TTA to the total light emission. For example, since A = 0.23 in FIG. 2, the ratio of light emission derived from TTA to the total light emission is 23%.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples. In addition, this invention is not limited to the following Example.

<Synthesis Example 1>
The following compound (11) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 9- (2-naphthyl) anthracene (1-1))
Under an argon stream, 9-bromoanthracene (7.71 g, 30.0 mmol), 2-naphthylboronic acid (6.83 g, 33.0 mmol), palladium acetate (0) (0.112 g, 0.50 mmol), triphenyl Phosphine (0.262 g, 1.00 mmol) was dissolved in 120 ml of ethylene glycol dimethyl ether. Next, 45 ml of an aqueous solution containing 90 mmol of potassium carbonate was added, and the mixture was stirred for 23 hours while heating under reflux. After cooling to room temperature, the mixture was concentrated under reduced pressure, water was added, and the mixture was extracted with chloroform. The organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained solid was purified by column chromatography and recrystallized from dichloromethane-methanol to obtain the desired 9- (2-naphthyl) anthracene (1-1) white powder (yield 7.26 g, 79%). Obtained.

(Synthesis of 9-bromo-10- (2-naphthyl) anthracene (1-2))
Under argon flow, 9- (2-naphthyl) anthracene (1-1) (7.25 g, 23.8 mmol) synthesized by the above reaction was dissolved in 180 ml of dehydrated dimethylformamide and cooled in an ice bath. 20 ml of a dehydrated dimethylformamide solution containing 25.0 mmol of N-bromosuccinimide was added dropwise over 10 minutes, followed by stirring at room temperature for 18 hours. Water and methanol were added to the reaction solution, and the precipitated solid was filtered and washed with methanol. The obtained solid was dried under reduced pressure to obtain the desired 9-bromo-10- (2-naphthyl) anthracene (1-2) white powder (yield 7.92 g, yield 87%).

(Synthesis of 10- (2-naphthyl) anthracene-9-boronic acid (1-3))
9-Bromo-10- (2-naphthyl) anthracene (1-2) (7.92 g, 20.7 mmol) synthesized by the above reaction was dissolved in 180 ml of dehydrated tetrahydrofuran and cooled to −78 ° C. under an argon stream. . 14.2 ml of dehydrated hexane solution containing 22.7 mmol of n-butyllithium was added dropwise over 10 minutes, and then stirred at -78 ° C for 1 hour. Triisopropyl borate (7.18 ml, 31.1 mmol) was added dropwise over 5 minutes, and the mixture was stirred at −78 ° C. for 1 hour and then at room temperature for 3 hours. The reaction solution was cooled in an ice bath, diluted hydrochloric acid was added, and the mixture was stirred for 30 minutes and extracted with diethyl ether. The organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained composition organism was washed with diethyl ether to obtain the desired 10- (2-naphthyl) anthracene-9-boronic acid (1-3) white powder (yield 6.62 g, yield 92%).

(Synthesis of 2-bromo-7- (2-naphthyl) naphthalene (1-4))
Under an argon stream, 2-naphthylboronic acid (1.51 g, 8.8 mmol), 2,7-dibromonaphthalene (5.00 g, 17.5 mmol), tetrakis (triphenylphosphine) palladium (0) (0.300 g, 0.26 mmol) was dissolved in 100 ml of tetrahydrofuran. Next, 50 ml of an aqueous solution containing 100 mmol of potassium carbonate was added, and the mixture was stirred for 21 hours while heating under reflux. After cooling to room temperature, water was added to the reaction solution and extracted with toluene. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. The obtained crude product was purified by column chromatography to obtain the target 2-bromo-7- (2-naphthyl) naphthalene (1-4) white powder (yield 1.84 g, yield 63%). .

(Synthesis of 9- [7- (2-naphthyl) naphthalen-2-yl] -10- (2-naphthyl) anthracene (11))
(10- (2-naphthyl) anthracene-9-boronic acid (1-3) (1.74 g, 5.00 mmol), 2-bromo-7- (2-naphthyl) synthesized by the above reaction under an argon stream Naphthalene (1-4) (1.84 g, 5.53 mmol), tris (dibenzylideneacetone) dipalladium (0) (0.139 g, 0.15 mmol), 2-dicyclohexylphosphino-2 ′, 6′-dimethoxy Biphenyl (0.123 g, 0.30 mmol) and potassium phosphate tribasic acid (3.18 g, 15.0 mmol) were dissolved in 100 ml of toluene and stirred for 20 hours under reflux with heating. The mixture was concentrated, water was added, and the mixture was extracted with chloroform.The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. After purification by rotography, recrystallization from dichloromethane-methanol and toluene gave the desired white powder of 9- [7- (2-naphthyl) naphthalen-2-yl] -10- (2-naphthyl) anthracene (11) ( The product was further purified by sublimation to obtain a 99% pure product (purity confirmed by high performance liquid chromatography (HPLC)).

Note that, when mass analysis of the obtained compound was performed, a peak was confirmed at m / z = 556 (M ⁺ ) with respect to the molecular weight 556 of the compound (11), and the compound obtained in Synthesis Example 1 was converted to the compound ( 11).

<Synthesis Example 2>
The following compound (12) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 9- (1-naphthyl) anthracene (1-5))
Under an argon stream, 9-bromoanthracene (7.71 g, 30.0 mmol), 1-naphthylboronic acid (6.83 g, 33.0 mmol), palladium acetate (0) (0.112 g, 0.50 mmol), triphenyl Phosphine (0.262 g, 1.00 mmol) was dissolved in 120 ml of ethylene glycol dimethyl ether. Next, 45 ml of an aqueous solution containing 90 mmol of potassium carbonate was added, and the mixture was stirred for 23 hours while heating under reflux. After cooling to room temperature, the mixture was concentrated under reduced pressure, water was added, and the mixture was extracted with chloroform. The organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained solid was purified by column chromatography and recrystallized from dichloromethane-methanol to obtain the desired 9- (1-naphthyl) anthracene (1-5) white powder (yield 7.76 g, 85%). Obtained.

(Synthesis of 9-bromo-10- (1-naphthyl) anthracene (1-6))
Under an argon stream, 9- (1-naphthyl) anthracene (1-5) (7.76 g, 25.5 mmol) synthesized by the above reaction was dissolved in 180 ml of dehydrated dimethylformamide and cooled in an ice bath. 20 ml of a dehydrated dimethylformamide solution containing N-bromosuccinimide (4.99 g, 28.1 mmol) was added dropwise over 10 minutes, followed by stirring at room temperature for 15 hours. Water and methanol were added to the reaction solution, and the precipitated solid was filtered and washed with methanol. The obtained solid was dried under reduced pressure to obtain the target 9-bromo-10- (1-naphthyl) anthracene (1-6) white powder (yield: 8.31 g, yield: 85%).

(Synthesis of 10- (1-naphthyl) anthracene-9-boronic acid (1-7))
9-Bromo-10- (1-naphthyl) anthracene (1-6) (8.31 g, 21.6 mmol) synthesized by the above reaction was dissolved in 180 ml of dehydrated tetrahydrofuran and cooled to −78 ° C. under an argon stream. . 14.9 ml of dehydrated hexane solution containing 23.8 mmol of n-butyllithium was added dropwise over 10 minutes, and then stirred at -78 ° C. for 1 hour. Triisopropyl borate (7.48 ml, 32.4 mmol) was added dropwise over 5 minutes, and the mixture was stirred at -78 ° C for 1 hour and then at room temperature for 3 hours. The reaction solution was cooled in an ice bath, diluted hydrochloric acid was added, and the mixture was stirred for 30 minutes and extracted with diethyl ether. The organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained composition organism was washed with diethyl ether to obtain the desired white powder (yield 6.77 g, yield 90%) of 10- (1-naphthyl) anthracene-9-boronic acid (1-7).

(Synthesis of 9- [7- (2-naphthyl) naphthalen-2-yl] -10- (1-naphthyl) anthracene (12))
10- (1-Naphtyl) anthracene-9-boronic acid (1-7) (1.74 g, 5.00 mmol), 2-bromo-7- (2-naphthyl) naphthalene synthesized by the above reaction under an argon stream (1-4) (1.83 g, 5.50 mmol), tris (dibenzylideneacetone) dipalladium (0) (0.139 g, 0.15 mmol), 2-dicyclohexylphosphino-2 ′, 6′-dimethoxybiphenyl (0.123 g, 0.30 mmol) and potassium phosphate tribasic acid (3.18 g, 15.0 mmol) were dissolved in 100 ml of toluene and stirred for 20 hours under heating to reflux. After cooling to room temperature, the mixture was concentrated under reduced pressure, water was added, and the mixture was extracted with chloroform. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. The obtained crude product was purified by column chromatography and recrystallized from dichloromethane-methanol and toluene to give the desired 9- [7- (2-naphthyl) naphthalen-2-yl] -10- (1-naphthyl). An anthracene (12) white powder (yield 2.09 g, yield 75%) was obtained. Furthermore, sublimation purification was performed to obtain a 99% pure product (purity confirmed by high performance liquid chromatography (HPLC)).

Note that, when mass analysis of the obtained compound was performed, a peak was confirmed at m / z = 556 (M ⁺ ) with respect to the molecular weight 556 of the compound (12), and the compound obtained in Synthesis Example 2 was found to be the compound ( 12).

<Synthesis Example 3>
The following compound (13) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 2-bromo-7- (1-naphthyl) naphthalene (1-8))
Under an argon stream, 1-naphthylboronic acid (1.51 g, 8.8 mmol), 2,7-dibromonaphthalene (5.00 g, 17.5 mmol), tetrakis (triphenylphosphine) palladium (0) (0.300 g, 0.26 mmol) was dissolved in 100 ml of tetrahydrofuran. Next, 50 ml of an aqueous solution containing 100 mmol of potassium carbonate was added, and the mixture was stirred for 18 hours while heating under reflux. After cooling to room temperature, water was added to the reaction solution and extracted with toluene. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. The resulting crude product was purified by column chromatography to obtain the desired 2-bromo-7- (1-naphthyl) naphthalene (1-8) white powder (yield 1.91 g, yield 65%). .

(Synthesis of 9- [7- (1-naphthyl) naphthalen-2-yl] -10- (2-naphthyl) anthracene (13))
(10- (2-naphthyl) anthracene-9-boronic acid (1-3) (1.74 g, 5.00 mmol), 2-bromo-7- (1-naphthyl) synthesized by the above reaction under an argon stream Naphthalene (1-8) (1.83 g, 5.50 mmol), tris (dibenzylideneacetone) dipalladium (0) (0.139 g, 0.15 mmol), 2-dicyclohexylphosphino-2 ′, 6′-dimethoxy Biphenyl (0.123 g, 0.30 mmol) and potassium phosphate tribasic acid (3.18 g, 15.0 mmol) were dissolved in 100 ml of toluene and stirred for 18 hours under reflux with heating. The mixture was concentrated, water was added, and the mixture was extracted with chloroform.The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. After purification by romatography, recrystallization from dichloromethane-methanol and toluene gave the desired 9- [7- (1-naphthyl) naphthalen-2-yl] -10- (2-naphthyl) anthracene (13) white powder ( The product was further purified by sublimation to obtain a 99% pure product (purity confirmed by high performance liquid chromatography (HPLC)).

Note that, when mass analysis of the obtained compound was performed, a peak was confirmed at m / z = 556 (M ⁺ ) with respect to the molecular weight 556 of the compound (13), and the compound obtained in Synthesis Example 3 was found to be the compound ( 13).

<Synthesis Example 4>
The following compound (14) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 9- [7- (1-naphthyl) naphthalen-2-yl] -10- (1-naphthyl) anthracene (14))
(10- (1-naphthyl) anthracene-9-boronic acid (1-7) (1.74 g, 5.00 mmol), 2-bromo-7- (1-naphthyl) synthesized by the above reaction under an argon stream Naphthalene (1-8) (1.83 g, 5.50 mmol), tris (dibenzylideneacetone) dipalladium (0) (0.139 g, 0.15 mmol), 2-dicyclohexylphosphino-2 ′, 6′-dimethoxy Biphenyl (0.123 g, 0.30 mmol) and potassium phosphate tribasic acid (3.18 g, 15.0 mmol) were dissolved in 100 ml of toluene and stirred for 21 hours while heating under reflux. The mixture was concentrated, water was added, and the mixture was extracted with chloroform.The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. After purification by rotography, recrystallization from dichloromethane-methanol and toluene gave the desired 9- [7- (1-naphthyl) naphthalen-2-yl] -10- (1-naphthyl) anthracene (14) white powder ( Further, sublimation purification was performed to obtain a 99% pure product (purity confirmed by high performance liquid chromatography (HPLC)).

Note that, when mass analysis of the obtained compound was performed, a peak was confirmed at m / z = 556 (M ⁺ ) with respect to the molecular weight 556 of the compound (14), and the compound obtained in Synthesis Example 4 was converted to the compound ( 14).

<Synthesis Example 5>
The following compound (15) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 7- (1-naphthyl) naphthalene-2-boronic acid (1-9))
Under an argon stream, 2-bromo-7- (1-naphthyl) naphthalene (1-8) (6.66 g, 20.0 mmol) synthesized by the above reaction was dissolved in 100 ml of dehydrated tetrahydrofuran and cooled to -78 ° C. . 13.8 ml of dehydrated hexane solution containing 22.0 mmol of n-butyllithium was added dropwise over 10 minutes, followed by stirring at -78 ° C for 1 hour. Triisopropyl borate (6.92 ml, 30.0 mmol) was added dropwise over 5 minutes, stirred at −78 ° C. for 1 hour, and then stirred at room temperature for 3 hours. The reaction solution was cooled in an ice bath, diluted hydrochloric acid was added, and the mixture was stirred for 30 minutes and extracted with diethyl ether. The organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained compositional organism was washed with diethyl ether to obtain the desired white powder (yield 5.19 g, 87%) of 7- (1-naphthyl) naphthalene-2-boronic acid (1-9).

(Synthesis of 9- [7- (1-naphthyl) naphthalen-2-yl] anthracene (1-10))
7- (1-Naphtyl) naphthalene-2-boronic acid (1-9) (5.19 g, 17.4 mmol) and 9-bromoanthracene (3.73 g, 14.5 mmol) synthesized by the above reaction under an argon stream ), Palladium acetate (0) (0.067 g, 0.30 mmol) and triphenylphosphine (0.157 g, 0.60 mmol) were dissolved in 180 ml of ethylene glycol dimethyl ether. Next, 22 ml of an aqueous solution containing 44 mmol of potassium carbonate was added, and the mixture was stirred for 16 hours under reflux with heating. After cooling to room temperature, the mixture was concentrated under reduced pressure, water was added, and the mixture was extracted with chloroform. The organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained solid was purified by column chromatography and recrystallized from dichloromethane-methanol to obtain the desired 9- [7- (1-naphthyl) naphthalen-2-yl] anthracene (1-10) white powder (yield 4 .87 g, 78% yield).

(Synthesis of 9-bromo-10- [7- (1-naphthyl) naphthalen-2-yl] anthracene (1-11))
9- [7- (1-naphthyl) naphthalen-2-yl] anthracene (1-10) (4.87 g, 11.3 mmol) synthesized by the above reaction was dissolved in 150 ml of dehydrated dimethylformamide under an argon stream. Cooled in an ice bath. 10 ml of a dehydrated dimethylformamide solution containing 12.4 mmol of N-bromosuccinimide was added dropwise over 10 minutes, and then stirred at room temperature for 17 hours. Water and methanol were added to the reaction solution, and the precipitated solid was filtered and washed with methanol. The obtained solid was dried under reduced pressure, and the desired 9-bromo-10- [7- (1-naphthyl) naphthalen-2-yl] anthracene (1-11) (yield 5.12 g, 89% yield) white A powder was obtained.

(Synthesis of 10- [7- (1-naphthyl) naphthalen-2-yl] anthracene-9-boronic acid (1-12))
9-Bromo-10- [7- (1-naphthyl) naphthalen-2-yl] anthracene (1-11) (5.12 g, 10.0 mmol) synthesized by the above reaction in an argon stream was added to 200 ml of dehydrated tetrahydrofuran. Dissolved and cooled to -78 ° C. 6.88 ml of dehydrated hexane solution containing 11.0 mmol of n-butyllithium was added dropwise over 10 minutes, and then stirred at −78 ° C. for 1 hour. Triisopropyl borate (3.46 ml, 15.0 mmol) was added dropwise over 5 minutes, stirred at −78 ° C. for 1 hour, and then stirred at room temperature for 3 hours. The reaction solution was cooled in an ice bath, diluted hydrochloric acid was added, and the mixture was stirred for 30 minutes and extracted with diethyl ether. The organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained composition organism was washed with diethyl ether, and the desired 10- [7- (1-naphthyl) naphthalen-2-yl] anthracene-9-boronic acid (1-12) (yield 3.98 g, yield 84). %) Of white powder.

(Synthesis of 9- [7- (1-naphthyl) naphthalen-2-yl] -10- [7- (2-naphthyl) naphthalen-2-yl] anthracene (15))
10- [7- (1-Naphtyl) naphthalen-2-yl] anthracene-9-boronic acid (1-12) (2.37 g, 5.00 mmol), 2-bromo synthesized by the above reaction under an argon stream -7- (2-naphthyl) naphthalene (1-4) (1.83 g, 5.50 mmol), tris (dibenzylideneacetone) dipalladium (0) (0.139 g, 0.15 mmol), 2-dicyclohexylphosphino -2 ', 6'-dimethoxybiphenyl (0.123 g, 0.30 mmol) and potassium phosphate tribasic acid (3.18 g, 15.0 mmol) were dissolved in 180 ml of toluene, and the mixture was stirred for 20 hours under heating to reflux. After cooling to room temperature, the mixture was concentrated under reduced pressure, water was added, and the mixture was extracted with chloroform. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. The obtained crude product was purified by column chromatography and recrystallized from dichloromethane-methanol and toluene to give the desired 9- [7- (1-naphthyl) naphthalen-2-yl] -10- [7- (2 -Naphthyl) naphthalen-2-yl] anthracene (15) white powder (2.56 g, 75% yield) was obtained. Furthermore, sublimation purification was performed to obtain a 99% pure product (purity confirmed by high performance liquid chromatography (HPLC)).

Note that, when mass analysis of the obtained compound was performed, a peak was confirmed at m / z = 682 (M ⁺ ) with respect to the molecular weight 682 of the compound (15), and the compound obtained in Synthesis Example 5 was found to be the compound ( 15).

<Synthesis Example 6>
The following compound (16) was synthesized by the following method. The reaction formula is shown below.

(Synthesis of 9,10-bis [7- (1-naphthyl) naphthalen-2-yl] anthracene (16))
10- [7- (1-Naphtyl) naphthalen-2-yl] anthracene-9-boronic acid (1-12) (2.37 g, 5.00 mmol), 2-bromo synthesized by the above reaction under an argon stream -7- (1-naphthyl) naphthalene (1-8) (1.83 g, 5.50 mmol), tris (dibenzylideneacetone) dipalladium (0) (0.139 g, 0.15 mmol), 2-dicyclohexylphosphino -2 ', 6'-dimethoxybiphenyl (0.123 g, 0.30 mmol) and potassium phosphate tribasic acid (3.18 g, 15.0 mmol) were dissolved in 180 ml of toluene, and the mixture was stirred for 24 hours with heating under reflux. After cooling to room temperature, the mixture was concentrated under reduced pressure, water was added, and the mixture was extracted with chloroform. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. The obtained crude product was purified by column chromatography and recrystallized from dichloromethane-methanol and toluene to obtain the desired 9,10-bis [7- (1-naphthyl) naphthalen-2-yl] anthracene (16). A white powder (yield 2.90 g, yield 85%) was obtained. Furthermore, sublimation purification was performed to obtain a 99% pure product (purity confirmed by high performance liquid chromatography (HPLC)).

Note that, when mass analysis of the obtained compound was performed, a peak was confirmed at m / z = 682 (M ⁺ ) with respect to the molecular weight 682 of the compound (16), and the compound obtained in Synthesis Example 6 was found to be the compound ( 16).

<Example 1>
An ITO transparent electrode having a thickness of 100 nm was formed on a glass substrate by RF sputtering and patterned. This glass substrate with an ITO transparent electrode was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, and then pulled up from boiling ethanol and dried. After the surface of the transparent electrode was washed with UV / O _3, it was fixed to a substrate holder of a vacuum deposition apparatus, and the inside of the layer was depressurized to 1 × 10 ⁻⁴ Pa or less.

Next, while maintaining the reduced pressure state, N, N′-diphenyl-N, N′— having the following structure:
Bis [N- (4-methylphenyl) -N-phenyl- (4-aminophenyl)]-1,1
50 nm of '-biphenyl-4,4'-diamine (21) at a deposition rate of 0.1 nm / sec.
The hole injection layer was formed as a hole injection layer.

  Next, N, N, N ′, N′-tetrakis (3-biphenylyl) -1,1′-biphenyl-4,4′-diamine (22) having the following structure was deposited while maintaining the reduced pressure state. Vapor deposition was performed at a thickness of 80 nm at 0.1 nm / sec to form a hole transport layer.

  Further, while maintaining the reduced pressure state, the compound (11) of the present invention as the host material and the compound (23) having the following structure as the dopant at a mass ratio of 97: 3 and an overall deposition rate of 0.1 nm / sec. As a light emitting layer, a film having a thickness of 40 nm was deposited.

  Further, while maintaining the reduced pressure state, the compound (11) of the present invention was deposited to a thickness of 20 nm at a deposition rate of 0.1 nm / sec to form an electron transport layer.

Further, while maintaining the reduced pressure state, Alq ₃ was successively deposited to a thickness of 10 nm at a deposition rate of 0.1 nm / sec to form an electron injection layer.

  Next, LiF is deposited at a deposition rate of 0.1 nm / sec to a thickness of 0.5 nm, used as an electron injection electrode, Al is deposited as a protective electrode to a thickness of 100 nm, and finally glass sealed to organic electroluminescence. An element was obtained. The sublimation purification of the compound (11) can be performed at any stage as long as it is before vapor deposition.

When a direct current voltage was applied to the organic electroluminescence device, blue light emission derived from a light emitting dopant having a light emission efficiency of 7.5 cd / A was obtained at a current density of 10 mA / cm ² .

  Evaluation of the light emission ratio derived from TTA was performed as follows.

  A rectangular wave current (frequency: 100 Hz, positive current density: 10 mA / cm2 applied with a pulse width of 400 us, zero current density: 0 mA / cm2 applied) output from a pulse current generator (MODEL2502A OLED DRIVER manufactured by SUNWATER) as an organic light emitting device Then, the light emission from the device was detected by a photodiode, and the rectangular wave current and the light emission intensity were synchronized and taken in an oscilloscope (Tektronix TDS3034) to obtain a transient response characteristic. This was analyzed using Equation 2 to determine the TTA-derived luminescence ratio (TTA efficiency) with respect to the total luminescence.

  The TTA efficiency of the organic electroluminescent element prepared in Example 1 was 18%.

<Examples 2 to 40 and Comparative Examples 1 to 3>
An electroluminescent device was produced in the same manner as in Example 1 except that the compounds listed in Table 1 were used instead of the compound (11). Table 1 shows the luminous efficiency and TTA efficiency of these elements. The compound used for the comparative example has the structure shown below.

  According to Examples 1 to 40 and Comparative Examples 1 to 3, the organic electroluminescent elements in which the compounds used in Examples 1 to 40 are contained in the organic layer are the comparative compounds (31), (32), and (33). It was shown that it is possible to achieve high luminous efficiency because of the high TTA efficiency compared to the included organic electroluminescent device.

<Example 41>
When the organic electroluminescent element produced in Example 1 was stored at 85 ° C. and the light emission state after 300 hours was confirmed, it showed blue-green uniform light emission, and no change was seen in the uniformity of the light emitting surface before and after heating. It was.

<Examples 41 to 56>
The light emitting state of the device after being stored at 85 ° C. for 300 hours in the same manner as in Example 41 except that the device prepared in the example described in Table 2 was used instead of the organic electroluminescent device prepared in Example 1. It was confirmed. Table 2 shows the light emission states of these elements.

<Comparative example 4>
An electroluminescent device was prepared in the same manner as in Example 1 except that the compound 34 was used instead of the compound (11), and the light emitting state of the device after being stored at 85 ° C. for 300 hours was confirmed. A surface was observed.

<Comparative Example 5>
An electroluminescent device was prepared in the same manner as in Example 1 except that the compound 35 was used instead of the compound (11), and the light emitting state of the device after being stored at 85 ° C. for 300 hours was confirmed. A surface was observed.

  The compounds used in Examples 41 to 56 have a highly flexible structure in which the 2-position of naphthalene having a substituted or unsubstituted aromatic hydrocarbon ring group at the 7-position is substituted at the 9-position of the anthracene ring. On the other hand, the comparative compounds (34) and (35) are compounds in which the 1-position of the naphthalene having a substituent at the 2-position or 4-position of the naphthalene having a substituent at the 6-position is substituted at the 9-position of the anthracene ring. According to Examples 41 to 56 and Comparative Examples 4 and 5, the compounds used in Examples 41 to 56 have a high molecular flexibility, so that they have a low crystallinity and form a stable thin film. It was shown that a stable and uniform light emitting surface can be maintained even when stored at a high temperature when used as a material for use. In other words, the organic electroluminescent device containing the compounds used in Examples 41 to 56 in the organic layer can suppress heat generation due to driving and crystallization due to aging of the thin film. A light-emitting element can be realized.

  As described in detail above, the compound for organic electroluminescence device of the present invention can achieve high luminous efficiency and high stability of organic electroluminescence device by containing this in the organic thin film layer. Can do.

DESCRIPTION OF SYMBOLS 1 ... Organic electroluminescent element concerning this embodiment, 2 ... Board | substrate, 3 ... 1st electrode, 4 ... Hole injection layer, 5 ... Hole transport layer, 6 ... Light emitting layer, 7 ... Electron transport layer, 8 ... Electron injection Layer, 9 ... second electrode, P ... power source.

Claims (4)

The compound for organic electroluminescent elements represented by following General formula (1).

(In the formula, Ar ¹ is a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon ring group, and Ar ² is a substituted or unsubstituted aromatic hydrocarbon ring group.
In the general formula (1), at least three naphthalene rings are included. )   The compound for organic electroluminescent elements according to claim 1, comprising at least four naphthalene rings in the general formula (1). The compound for organic electroluminescent elements represented by following General formula (2).

(In the formula, Ar ³ is a substituted or unsubstituted aromatic hydrocarbon ring group.
In general formula (2), at least 4 naphthalene rings are included. )   In the organic electroluminescent element in which at least one organic layer is sandwiched between a pair of electrodes composed of an anode and a cathode, at least one layer of the organic layer is a compound of claim 1, 2 or 3 alone. Or it contains as a component of a mixture, The organic electroluminescent element characterized by the above-mentioned.

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