JP2016127181A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent element with high efficiency and a long life.SOLUTION: The organic electroluminescent element includes: a first layer 121, including a lamination structure of three or more layers of different film constitutions between a positive electrode and a light-emitting layer, whose lamination structure includes a hole transport compound doped with an electron-accepting compound; and a second layer 125, disposed between the first layer and the light-emitting layer 130, adjacent to the light-emitting layer, containing a compound represented by the general formula (1).SELECTED DRAWING: Figure 1

Description

  The present invention relates to an organic electroluminescence element. In particular, the present invention relates to a high-efficiency and long-life organic electroluminescence element.

  In recent years, organic electroluminescence display (organic EL display) has been actively developed as an image display device. Unlike a liquid crystal display device or the like, an organic EL display device recombines holes and electrons injected from an anode and a cathode in a light emitting layer, thereby causing a light emitting material containing an organic compound in the light emitting layer to emit light for display. This is a so-called self-luminous display device to be realized.

  Examples of the organic electroluminescence element (organic EL element) include an anode, a hole transport layer disposed on the anode, a light emitting layer disposed on the hole transport layer, an electron transport layer disposed on the light emitting layer, and An organic electroluminescence element composed of a cathode disposed on an electron transport layer is known. Holes are injected from the anode, and the injected holes move through the hole transport layer and are injected into the light emitting layer. On the other hand, electrons are injected from the cathode, and the injected electrons move through the electron transport layer and are injected into the light emitting layer. Excitons are generated in the light emitting layer by recombination of holes and electrons injected into the light emitting layer. An organic electroluminescence element emits light using light generated by radiation deactivation of its excitons. The organic electroluminescence element is not limited to the above-described configuration, and various modifications can be made.

  In applying an organic electroluminescence element to a display device, high efficiency and long life of the organic electroluminescence element are required. In particular, in the blue light emission region and the green light emission region, it is difficult to say that the light emission efficiency and lifetime of the organic electroluminescence element are sufficient. In order to achieve high efficiency of the organic electroluminescence element, it is important to stabilize and stabilize the band between the anode and the light emitting layer and the light emitting layer. For this reason, it has been proposed to dispose a layer containing an electron acceptor material (hereinafter referred to as an acceptor layer) for the purpose of assisting hole transport.

  Various compounds such as anthracene derivatives and aromatic amine compounds are known as hole transport materials used for the hole transport layer, but in order to achieve higher efficiency of organic electroluminescent devices, new New materials need to be developed. For example, Patent Document 1 proposes an organic electroluminescent element using an amine compound for a hole transport layer. Patent Document 2 discloses an organic material containing an electron acceptor dopant whose LUMO level is −9.0 eV or more and −4.0 eV or less in at least one of the organic material layers disposed between the light emitting layer and the anode. A light emitting device has been proposed.

  Further, in Patent Document 3 in which the relationship between the material and the structure of the organic electroluminescence element was examined, a hole transport layer made of an amine derivative having a carbazole part and a fluorene part was laminated in contact with the light emitting layer, and the anode and the An organic electroluminescence device having a three-layered hole injection layer between the hole transport layer and the hole transport layer has been proposed. The hole injection layer has (1) a carbazole portion on each of two nitrogen atoms from the anode side. A layer containing a bonded diamine derivative, (2) a layer containing a diamine derivative having a carbazole moiety bonded to each of two nitrogen atoms and an amine derivative having a carbazole moiety and a fluorene moiety bonded to the nitrogen atom, and (3) a layer containing HAT It is described that it is formed by. Patent Document 4 discloses (1) a layer containing an amine derivative having a carbazole part and a fluorene part between the anode and the light emitting layer, and (2) an amine having a carbazole part and a fluorene part doped with HAT. A layer containing a derivative, and (3) a repeating structure of a layer containing an amine derivative having a carbazole part and a fluorene part, and the light emitting layer is disposed so that a layer containing an amine derivative having a carbazole part and a fluorene part is in contact Organic electroluminescence devices have been proposed.

International Publication No. 2014/104515 International Publication No. 2007/105906 Korean Published Patent No. 10-2013-0007159 JP 2011-187959 A

  Many studies have been made on materials for forming a specific layer of the organic electroluminescence device, but there are few studies including the configuration of the device. Furthermore, in order to realize an organic electroluminescence device with higher efficiency and longer life, the configurations of Patent Documents 3 and 4 are not sufficient, and further examination is necessary for the combination of materials and layer configurations. It was.

  The present invention solves the above-described problems, and an object thereof is to provide a highly efficient and long-life organic electroluminescence element.

According to one embodiment of the present invention, a laminate structure of three or more layers having different film compositions is provided between an anode and a light emitting layer, and the laminate structure comprises a hole transporting compound doped with an electron accepting compound. A first layer including, a second layer disposed between the first layer and the light emitting layer, and adjacent to the light emitting layer and including a compound represented by the following general formula (1): The organic electroluminescent element characterized by including these is provided.

In general formula (1), Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring carbon number of 5 The heteroaryl group is 50 or less and at least one of Ar ₁ and Ar ₂ is a dibenzoheterol group represented by the following general formula (2), and L ₁ , L ₂ and L ₃ are each independently a single group. A bond, a substituted or unsubstituted arylene group having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having 4 to 15 ring carbon atoms, and in the general formula (2), X is O or S and each R ₁ is independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 4 to 50 ring carbon atoms, m is 0 or more and 4 or less It is an integer.

  The organic electroluminescent device according to an embodiment of the present invention can improve the hole injection property from the anode and can protect the hole transporting stacked structure from the electrons that are not consumed in the light emitting layer. It is possible to prevent the excited state energy generated in the layer from diffusing into the hole-transporting laminated structure, and further to adjust the charge balance of the entire device, thereby improving the luminous efficiency and extending the lifetime. it can.

According to one embodiment of the present invention, the organic electroluminescence device includes a third layer containing a compound represented by the following general formula (3) between the first layer and the second layer. May be included.

In General Formula (3), Ar ₅ , Ar ₆ and Ar ₇ are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring forming carbon number of 5 to 50. And Ar ₈ is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 50 ring carbon atoms, or substituted or unsubstituted And an alkyl group having 1 to 50 carbon atoms, L ₄ is a single bond, a substituted or unsubstituted arylene group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring carbon atom having 5 to 50 carbon atoms. A heteroarylene group.

  The organic electroluminescent device according to one embodiment of the present invention can improve the hole transport property and the current-carrying durability by including a compound having a carbazolyl group in the hole transport layered structure. Improvement and long life can be achieved.

  According to an embodiment of the present invention, the electron accepting compound may have a LUMO level of −9.0 eV to −4.0 eV.

  The organic electroluminescence device according to an embodiment of the present invention can achieve improvement in luminous efficiency and long life.

  According to an embodiment of the present invention, the first layer may be disposed adjacent to the anode.

  The organic electroluminescence device according to an embodiment of the present invention can achieve improvement in luminous efficiency and long life.

  According to an embodiment of the present invention, the light emitting layer may include a light emitting material that emits light mainly through a singlet excited state.

  The organic electroluminescence device according to an embodiment of the present invention can achieve improvement in luminous efficiency and long life.

According to an embodiment of the present invention, the light emitting material may include a compound represented by the following general formula (4).

In the general formula (4), Ar ₉ is independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cyclocarbon having 3 to 50 ring carbon atoms. An alkyl group, a substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms, and a substituted or unsubstituted aryloxy group having 6 to 50 ring carbon atoms. A substituted or unsubstituted arylthio group having 6 to 50 ring carbon atoms, a substituted or unsubstituted alkoxycarbonyl group having 2 to 50 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms A substituted or unsubstituted heteroaryl group having 5 to 50 carbon atoms, a substituted or unsubstituted silyl group, a carboxyl group, a halogen atom A child, a cyano group, a nitro group, or a hydroxyl group, and n is an integer of 1-10.

  The organic electroluminescence device according to an embodiment of the present invention can achieve improvement in luminous efficiency and long life.

  According to the present invention, it is possible to provide an organic electroluminescence device with high efficiency and long life.

It is a schematic diagram which shows the organic electroluminescent element 100 which concerns on one Embodiment of this invention. It is a schematic diagram which shows the organic electroluminescent element 200 which concerns on one Example of this invention.

  As a result of intensive investigations to solve the above problems, the present inventors have found that the hole injection property from the anode can be improved by arranging a layer doped with an electron accepting compound on the anode side. The headline and invention were completed. In the present invention, a hole transporting multilayer film between a light emitting layer and an anode is considered as one structure, and a hole transporting layer doped with an electron accepting material in the layered structure is arranged on the anode side. An intermediate layer containing an amine derivative having a dibenzoheterol group is laminated on the light emitting layer side.

  Hereinafter, an organic electroluminescence device according to the present invention will be described with reference to the drawings. However, the organic electroluminescence device of the present invention can be implemented in many different modes, and is not construed as being limited to the description of the embodiments described below. Note that in the drawings referred to in this embodiment, the same portions or portions having similar functions are denoted by the same reference numerals, and repetitive description thereof is omitted.

  The organic electroluminescence element according to the present invention will be described. FIG. 1 is a schematic view showing an organic electroluminescence element 100 according to an embodiment of the present invention. The organic electroluminescence device 100 includes, for example, an anode 110, a light emitting layer 130, an electron transport layer 140, an electron injection layer 150, and a cathode 160 on a substrate 101. A hole transport zone 120 is disposed between the anode 110 and the light emitting layer 130. The hole transport zone 120 is a zone where a hole transport layer, a hole injection layer, and the like are arranged.

In the present invention, three or more layers having different film compositions are stacked in the hole transport zone 120 between the anode 110 and the light emitting layer 130 in order to improve the light emission efficiency and extend the life of the organic electroluminescence element. Provide structure. The stacked structure includes at least a first layer 121 and a second layer 125. At least one layer (first layer 121) disposed on the anode 110 side of the stacked structure includes a hole transporting compound doped with an electron accepting compound. In addition, at least one layer (second layer 125) disposed between the first layer 121 and the light emitting layer 130 and adjacent to the light emitting layer is represented by the following general formula (1). Contains compounds.

In general formula (1), Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring carbon number. 5 or more and 50 or less heteroaryl group, and at least one of Ar ₁ and Ar ₂ is a dibenzoheterol group represented by the following general formula (2). , L ₁ , L ₂ and L ₃ are each independently a single bond, a substituted or unsubstituted arylene group having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having 4 to 15 ring carbon atoms. It is a group.

The dibenzoheterol group represented by the general formula (2) is shown below.

In general formula (2), X is O or S, and R ₁ is independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring carbon number of 4 The heteroaryl group is 50 or more and m is an integer of 0 or more and 4 or less. Note that * represents a bonding position between L ₂ and / or L _3.

Specific examples of Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ are phenyl, biphenyl, terphenyl, naphthyl, anthryl, phenanthryl, fluorenyl, indenyl, pyrenyl, acetonaphthenyl, fluorane. Tenenyl, triphenylenyl, pyridyl, pyranyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, benzoxazolyl, benzothiazolyl, quinoxalyl, benzoimidazolyl, dibenzofuranyl And a dibenzothienyl group. Preferred examples include a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a carbazolyl group, and a dibenzofuranyl group.

As L ₁ , L ₂ and L ₃ , in addition to a single bond, specifically, a phenylene group, a biphenylylene group, a terphenylylene group, a naphthylene group, an anthrylene group, a phenanthrylene group, a fluorylene group, an indandiyl group, a pyrenediyl group, an acenaphthene group Diyl group, fluoranthene diyl group, triphenylenediyl group, pyridinediyl group, pyrandiyl group, quinolinediyl group, isoquinolinediyl group, benzofuranyl group, benzothiophenediyl group, indolediyl group, carbazolediyl group, benzoxazolediyl group, benzo Examples thereof include a thiazole diyl group, a quinoxaline diyl group, a benzimidazole diyl group, and a dibenzofurandyl group. Preferable examples include phenylene group, terphenylene group, fluorenediyl group, carbazolediyl group, dibenzofurandiyl group and the like.

As described above, in the general formula (1), at least one of Ar ₁ and Ar ₂ is a dibenzoheterol group represented by the general formula (2) in which X is O or S. That is, at least one of Ar ₁ and Ar ₂ is a dibenzofuranyl group or a dibenzothienyl group. Here, both Ar ₁ and Ar ₂ are preferably dibenzoheteroal groups represented by the general formula (2). In the general formula (1), at least one of Ar ₁ and Ar ₂ is a dibenzoheteroal group represented by the general formula (2) in which X is O or S, whereby the luminous efficiency and lifetime of the organic electroluminescence device Improvement can be expected.

Specific examples of R ₁ include phenyl, biphenyl, terphenyl, naphthyl, anthryl, phenanthryl, fluorenyl, indenyl, pyrenyl, acetonaphthenyl, fluoranthenyl, triphenylenyl, pyridyl, List pyranyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, benzoxazolyl, benzothiazolyl, quinoxalyl, benzoimidazolyl, dibenzofuranyl, and dibenzothienyl Can do. Preferred examples include a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a carbazolyl group, and a dibenzofuranyl group.

When m is an integer of 2 or more, R ₁ may be the same or different. When m is an integer of 2 or more, adjacent R ₁ may be bonded to each other to form an unsaturated ring.

  The compound represented by the general formula (1) is a compound represented by the following structural formula as an example. However, the compound represented by the general formula (1) is not limited to the following.

  At least one layer (first layer 121) disposed on the anode 110 side of the stacked structure includes a hole transporting compound doped with an electron accepting compound. The electron-accepting compound doped in the first layer 121 may have a LUMO level of −9.0 eV or more and −4.0 eV or less. The electron-accepting compound doped in the first layer 121 is, for example, a compound represented by the following structural formulas a1 to a14. However, the electron-accepting compound according to the present invention is not limited to the following. In the present invention, the doping amount of the electron-accepting compound is preferably 0.1% by mass or more and less than 50% by mass with respect to the total mass of all the materials constituting the first layer 121. More preferably, it is 0.5 mass% or more and 5 mass% or less.

  In the above electron-accepting compounds a1 to a14, R is a hydrogen atom, deuterium atom, halogen atom, fluorinated alkyl group having 1 to 10 carbon atoms, cyano group, alkoxy group having 1 to 10 carbon atoms, carbon number An alkyl group having 1 to 10 carbon atoms or a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms. However, not all hydrogen atoms, deuterium atoms or fluorine atoms are substituted in the same molecule. Ar is each independently an electron-withdrawing substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms or a substituted or unsubstituted heteroaryl group having 3 to 30 ring carbon atoms. Y is a methine group (-CH =) or a nitrogen atom (-N =). Z is a pseudohalogen or sulfur atom (S). X is any of the substituents ax1 to ax7 shown below.

  Here, Ra is a hydrogen atom, a deuterium halogen atom, a fluorinated alkyl group having 1 to 10 carbon atoms, a cyano group, an alkoxy group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or a substituent. Alternatively, it is an unsubstituted aryl group having 6 to 30 ring carbon atoms or a substituted or unsubstituted heteroaryl group having 3 to 30 ring carbon atoms.

  Examples of the substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms or the substituted or unsubstituted heteroaryl group having 3 to 30 ring carbon atoms represented by R, Ar, and Ra include a phenyl group, 1 -Naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 9-anthryl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group, 4-phenanthryl group, 9-phenanthryl group, 1 -Naphthacenyl group, 2-naphthacenyl group, 9-naphthacenyl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group, p-ter Phenyl-4-yl group, p-terphenyl-3-yl group, p-terphenyl-2-yl group, m-terphenyl-4-yl group, m-turf Nyl-3-yl group, m-terphenyl-2-yl group, o-tolyl group, m-tolyl group, p-tolyl group, pt-butylphenyl group, p- (2-phenylpropyl) phenyl group 3-methyl-2-naphthyl group, 4-methyl-1-naphthyl group, 4-methyl-1-anthryl group, 4′-methylbiphenylyl group, 4 ″ -t-butyl-p-terphenyl-4- Yl group, fluoranthenyl group, fluorenyl group, 1-pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group, pyrazinyl group, 2-pyridinyl group, 3-pyridinyl group, 4-pyridinyl group, 1-indolyl group, 2 -Indolyl group, 3-indolyl group, 4-indolyl group, 5-indolyl group, 6-indolyl group, 7-indolyl group, 1-isoindolyl group, 2-isoindolyl group, 3-isoindolyl group, 4 -Isoindolyl group, 5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group, 2-furyl group, 3-furyl group, 2-benzofuranyl group, 3-benzofuranyl group, 4-benzofuranyl group, 5-benzofuranyl group, 6 -Benzofuranyl group, 7-benzofuranyl group, 1-isobenzofuranyl group, 3-isobenzofuranyl group, 4-isobenzofuranyl group, 5-isobenzofuranyl group, 6-isobenzofuranyl group, 7 -Isobenzofuranyl group, quinolyl group, 3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 6-isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group, 2-quinoxalini Group, 5-quinoxalinyl group, 6-quinoxalinyl group, 1-carbazolyl group, 2-carbazolyl group, 3-carbazolyl group, 4-carbazolyl group, 9-carbazolyl group, 1-phenanthridinyl group, 2-phenanthridinyl group Group, 3-phenanthridinyl group, 4-phenanthridinyl group, 6-phenanthridinyl group, 7-phenanthridinyl group, 8-phenanthridinyl group, 9-phenanthridinyl group 10-phenanthridinyl group, 1-acridinyl group, 2-acridinyl group, 3-acridinyl group, 4-acridinyl group, 9-acridinyl group, 1,7-phenanthrolin-2-yl group, 1,7 -Phenanthrolin-3-yl group, 1,7-phenanthrolin-4-yl group, 1,7-phenanthrolin-5-yl group, 1,7-phenanthrolin-6 Yl group, 1,7-phenanthroline-8-yl group, 1,7-phenanthrolin-9-yl group, 1,7-phenanthrolin-10-yl group, 1,8-phenanthroline- 2-yl group, 1,8-phenanthrolin-3-yl group, 1,8-phenanthrolin-4-yl group, 1,8-phenanthrolin-5-yl group, 1,8-phenance Lorin-6-yl group, 1,8-phenanthrolin-7-yl group, 1,8-phenanthrolin-9-yl group, 1,8-phenanthrolin-10-yl group, 1,9- Phenanthrolin-2-yl group, 1,9-phenanthrolin-3-yl group, 1,9-phenanthrolin-4-yl group, 1,9-phenanthrolin-5-yl group, 1, 9-phenanthrolin-6-yl group, 1,9-phenanthrolin-7-yl group, 1,9- Phenanthrolin-8-yl group, 1,9-phenanthrolin-10-yl group, 1,10-phenanthrolin-2-yl group, 1,10-phenanthrolin-3-yl group, 1, 10-phenanthrolin-4-yl group, 1,10-phenanthrolin-5-yl group, 2,9-phenanthrolin-1-yl group, 2,9-phenanthrolin-3-yl group, 2,9-phenanthrolin-4-yl group, 2,9-phenanthrolin-5-yl group, 2,9-phenanthrolin-6-yl group, 2,9-phenanthrolin-7-yl Group, 2,9-phenanthrolin-8-yl group, 2,9-phenanthrolin-10-yl group, 2,8-phenanthrolin-1-yl group, 2,8-phenanthroline-3 -Yl group, 2,8-phenanthrolin-4-yl group, 2,8-phenane Lorin-5-yl group, 2,8-phenanthrolin-6-yl group, 2,8-phenanthrolin-7-yl group, 2,8-phenanthrolin-9-yl group, 2,8- Phenanthrolin-10-yl group, 2,7-phenanthrolin-1-yl group, 2,7-phenanthrolin-3-yl group, 2,7-phenanthrolin-4-yl group, 2, 7-phenanthrolin-5-yl group, 2,7-phenanthrolin-6-yl group, 2,7-phenanthrolin-8-yl group, 2,7-phenanthrolin-9-yl group, 2,7-phenanthrolin-10-yl group, 1-phenazinyl group, 2-phenazinyl group, 1-phenothiazinyl group, 2-phenothiazinyl group, 3-phenothiazinyl group, 4-phenothiazinyl group, 10-pheno Thiazinyl group, 1-phenoxazinyl group 2-phenoxazinyl group, 3-phenoxazinyl group, 4-phenoxazinyl group, 10-phenoxazinyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group, 2-oxadiazolyl group, 5-oxadiazolyl group, 3-flazanyl group, 2-thienyl group, 3-thienyl group, 2-methylpyrrol-1-yl group, 2-methylpyrrol-3-yl group, 2-methylpyrrol-4-yl group, 2-methylpyrrol-5-yl group, 3-methylpyrrol-1-yl group, 3-methylpyrrol-2-yl group, 3-methylpyrrol-4-yl group, 3-methylpyrrol-5-yl group, 2-t-butylpyrrol-4-yl Group, 3- (2-phenylpropyl) pyrrol-1-yl group, 2-methyl-1-indolyl group, 4-methyl-1-indolyl group, 2-methyl Lu-3-indolyl group, 4-methyl-3-indolyl group, 2-t-butyl 1-indolyl group, 4-t-butyl 1-indolyl group, 2-t-butyl 3-indolyl group, 4-t- A butyl 3-indolyl group etc. are mentioned.

  Examples of the fluorinated alkyl group having 1 to 10 carbon atoms represented by R and Ra include perfluoroalkyl groups such as a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, and a heptadecafluorooctane group, or mono Examples thereof include a fluoromethyl group, a difluoromethyl group, a tritrifluoroethyl group, a tetrafluoropropyl group, and an octafluoropentyl group.

  Examples of the alkyl group having 1 to 10 carbon atoms represented by R and Ra include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, isobutyl group, t-butyl group, n -Pentyl group, n-hexyl group, n-heptyl group, n-octyl group, hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 2-hydroxyisobutyl group, 1,2-dihydroxyethyl group, 1 , 3-dihydroxyisopropyl group, 2,3-dihydroxy-t-butyl group, 1,2,3-trihydroxypropyl group, chloromethyl group, 1-chloroethyl group, 2-chloroethyl group, 2-chloroisobutyl group, 1 , 2-dichloroethyl group, 1,3-dichloroisopropyl group, 2,3-dichloro-t-butyl group, 1,2,3-trichloropropyl group, Momethyl group, 1-bromoethyl group, 2-bromoethyl group, 2-bromoisobutyl group, 1,2-dibromoethyl group, 1,3-dibromoisopropyl group, 2,3-dibromo-t-butyl group, 1,2, 3-tribromopropyl group, iodomethyl group, 1-iodoethyl group, 2-iodoethyl group, 2-iodoisobutyl group, 1,2-diiodoethyl group, 1,3-diiodoisopropyl group, 2,3-diiodo-t- Butyl group, 1,2,3-triiodopropyl group, aminomethyl group, 1-aminoethyl group, 2-aminoethyl group, 2-aminoisobutyl group, 1,2-diaminoethyl group, 1,3-diaminoisopropyl Group, 2,3-diamino-t-butyl group, 1,2,3-triaminopropyl group, cyanomethyl group, 1-cyanoethyl group, 2-cyanoethyl group, -Cyanoisobutyl group, 1,2-dicyanoethyl group, 1,3-dicyanoisopropyl group, 2,3-dicyano-t-butyl group, 1,2,3-tricyanopropyl group, nitromethyl group, 1-nitroethyl group 2-nitroethyl group, 2-nitroisobutyl group, 1,2-dinitroethyl group, 1,3-dinitroisopropyl group, 2,3-dinitro-t-butyl group, 1,2,3-trinitropropyl group, Examples include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a 4-methylcyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-norbornyl group, and a 2-norbornyl group.

  The alkoxy group having 1 to 10 carbon atoms represented by R and Ra is a group represented by -OY, and examples of Y include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s- Butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 2-hydroxy Isobutyl group, 1,2-dihydroxyethyl group, 1,3-dihydroxyisopropyl group, 2,3-dihydroxy-t-butyl group, 1,2,3-trihydroxypropyl group, chloromethyl group, 1-chloroethyl group, 2-chloroethyl group, 2-chloroisobutyl group, 1,2-dichloroethyl group, 1,3-dichloroisopropyl group, 2,3-dichloro-t-butyl group, 1, , 3-trichloropropyl group, bromomethyl group, 1-bromoethyl group, 2-bromoethyl group, 2-bromoisobutyl group, 1,2-dibromoethyl group, 1,3-dibromoisopropyl group, 2,3-dibromo-t- Butyl group, 1,2,3-tribromopropyl group, iodomethyl group, 1-iodoethyl group, 2-iodoethyl group, 2-iodoisobutyl group, 1,2-diiodoethyl group, 1,3-diiodoisopropyl group, 2 , 3-Diiodo-t-butyl group, 1,2,3-triiodopropyl group, aminomethyl group, 1-aminoethyl group, 2-aminoethyl group, 2-aminoisobutyl group, 1,2-diaminoethyl group 1,3-diaminoisopropyl group, 2,3-diamino-t-butyl group, 1,2,3-triaminopropyl group, cyanomethyl group, 1-sia Ethyl group, 2-cyanoethyl group, 2-cyanoisobutyl group, 1,2-dicyanoethyl group, 1,3-dicyanoisopropyl group, 2,3-dicyano-t-butyl group, 1,2,3-tricyanopropyl Group, nitromethyl group, 1-nitroethyl group, 2-nitroethyl group, 2-nitroisobutyl group, 1,2-dinitroethyl group, 1,3-dinitroisopropyl group, 2,3-dinitro-t-butyl group, 1, Examples include 2,3-trinitropropyl group.

  Examples of the halogen atom represented by R and Ra include fluorine, chlorine, bromine and iodine.

  Here, as the hole transporting compound contained in the first layer 121, for example, an amine-based hole transporting compound such as DNTPD can be used. However, the hole transporting compound contained in the first layer 121 is not limited to an amine compound, and a known hole transporting compound can be used.

Further, in the stacked structure of three or more layers in the hole transport zone 120 of the organic electroluminescent element 100, a layer containing a compound represented by the following general formula (3) is provided between the anode 110 and the second layer 125. At least one layer (third layer 123) may be provided.

In general formula (3), Ar ₅ , Ar ₆ and Ar ₇ are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring forming carbon number of 5 to 50. Ar ₈ is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 50 ring carbon atoms, or a substituted or unsubstituted heteroaryl group. A substituted alkyl group having 1 to 50 carbon atoms, and L ₄ is a single bond, a substituted or unsubstituted arylene group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring carbon atom having 5 to 50 carbon atoms. The following heteroarylene groups.

Specifically, as Ar ₅ , Ar ₆ and Ar ₇ , phenyl group, biphenyl group, terphenyl group, naphthyl group, anthryl group, phenanthryl group, fluorenyl group, indenyl group, pyrenyl group, acetonaphthenyl group, fluoranthenyl group, Triphenylenyl, pyridyl, pyranyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, benzoxazolyl, benzothiazolyl, quinoxalyl, benzimidazolyl, dibenzofuranyl, and dibenzo A thienyl group etc. can be mentioned. Preferred examples include a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a carbazolyl group, and a dibenzofuranyl group.

As Ar ₈ , the aryl group and heteroaryl group are the same as the functional groups specifically mentioned as Ar ₅ , Ar ₆ and Ar ₇ , and the alkyl group is preferably a methyl group or an ethyl group.

In addition to a single bond, L ₈ is specifically a phenylene group, biphenylylene group, terphenylylene group, naphthylene group, anthrylene group, phenanthrylene group, fluorylene group, indandiyl group, pyrenediyl group, acenaphthenediyl group, fluoranthenediyl. Group, triphenylenediyl group, pyridinediyl group, pyrandiyl group, quinolinediyl group, isoquinolinediyl group, benzofurandiyl group, benzothiophenediyl group, indolediyl group, carbazolediyl group, benzoxazolediyl group, benzothiazolediyl group, quinoxalinediyl group , Benzimidazole diyl group and dibenzofurandiyl group. Preferable examples include phenylene group, terphenylene group, fluorenediyl group, carbazolediyl group, dibenzofurandiyl group and the like.

  The compound represented by the general formula (3) is, for example, a compound represented by the following structural formula. However, the compound represented by the general formula (3) is not limited to the following.

  The position of the third layer 123 in the stacked structure is not particularly limited, but it is preferably disposed between the first layer 121 and the second layer 125.

  In addition, in the organic electroluminescent element 100 of this invention, the compound represented by General formula (3) is not only the 3rd layer 123 but a hole transportable compound contained besides an electron-accepting compound is 1st. The layer 121 may be included.

  In the organic electroluminescent device 100, in the laminated structure of three or more layers having different film compositions disposed in the hole transport zone 120, the first layer containing a hole transporting compound doped with an electron accepting compound on the anode 110 side. At least one layer 121 is disposed, and at least one second layer 125 including the compound represented by the general formula (1) is disposed adjacent to the light emitting layer 130. The organic electroluminescence device 100 according to the present invention includes an amine derivative having a dibenzoheteroyl group in the hole transporting second layer 125 disposed adjacent to the light emitting layer 130 in a stacked structure, thereby emitting light. The hole-transporting stacked structure can be protected from electrons not consumed in the layer 130. In addition, it is possible to prevent the excited state energy generated in the light emitting layer 130 from diffusing into the hole transporting stacked structure, and to adjust the charge balance of the entire organic electroluminescent element 100.

  In the organic electroluminescent element 100, it is preferable that the first layer 121 doped with the electron accepting compound is disposed on the anode 110 side, particularly adjacent to the anode 110. By disposing a layer containing an electron-accepting compound adjacent to the anode 110, the hole injection property from the anode can be improved.

  In the organic electroluminescent element 100, it is preferable that the third layer 123 containing the compound having a carbazolyl group represented by the general formula (3) is disposed closer to the light emitting layer 130 than the first layer 121. . By including the compound having a carbazolyl group in the hole transporting stacked structure, the charge transporting property and the current-carrying durability can be improved. In addition, when the third layer 123 includes the compound represented by the general formula (3), the hole-transporting stacked structure is protected from electrons that are not consumed in the light-emitting layer 130 and is generated in the light-emitting layer 130. It is possible to prevent the excited state energy from diffusing into the hole transporting stacked structure. In addition, the compound represented by the general formula (3) which is an amine derivative having a carbazolyl group suppresses diffusion of the electron-accepting compound into the light-emitting layer 130.

  Further, the second layer 125 containing the compound represented by the general formula (1) is disposed adjacent to the light emitting layer 130, whereby the electron-accepting compound included in the first layer 121 is formed in the light emitting layer 130. In addition to suppressing diffusion, the first layer 121 and the third layer 123 having a hole transporting property are protected from electrons not consumed in the light emitting layer 130, and the excited state energy generated in the light emitting layer 130 is positive. Diffusion to the hole transporting first layer 121 and the third layer 123 can be prevented.

In the organic electroluminescent element 100, the light emitting layer 130 can emit light mainly through a singlet excited state. As a material of the light emitting layer 130, a known light emitting material can be used, and is not particularly limited, but is selected from fluoranthene derivatives, pyrene derivatives, arylacetylene derivatives, fluorene derivatives, perylene derivatives, chrysene derivatives and the like. Pyrene derivatives, perylene derivatives, and anthracene derivatives are preferable. For example, an anthracene derivative represented by the following general formula (4) may be used as the material of the light emitting layer 130.

In the general formula (4), each Ar ₉ is independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, or a substituted or unsubstituted ring forming carbon number of 3 to 50. A substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms. Oxy group, substituted or unsubstituted arylthio group having 6 to 50 ring carbon atoms, substituted or unsubstituted alkoxycarbonyl group having 2 to 50 carbon atoms, substituted or unsubstituted ring carbon atoms having 6 to 50 carbon atoms Aryl group, heteroaryl group having 5 to 50 ring carbon atoms, substituted or unsubstituted silyl group, carboxyl group, halogen atom, cyano group, A tro group or a hydroxyl group, and n is an integer of 1 or more and 10 or less.

Specific examples of Ar ₉ include phenyl, biphenyl, terphenyl, naphthyl, phenylnaphthyl, naphthylphenyl, anthryl, phenanthryl, fluorenyl, indenyl, pyrenyl, acetonaphthenyl, fluoranthenyl. Group, triphenylenyl group, pyridyl group, furanyl group, pyranyl group, thienyl group, quinolyl group, isoquinolyl group, benzofuranyl group, benzothienyl group, indolyl group, carbazolyl group, benzoxazolyl group, benzothiazolyl group, quinoxalyl group, benzoimidazolyl group , Pyrazolyl group, dibenzofuranyl group, and dibenzothienyl group. Preferred examples include a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a carbazolyl group, and a dibenzofuranyl group.

  As an example, the compound represented by the general formula (4) is a compound represented by the following structural formula. However, the compound represented by the general formula (4) is not limited to the following.

  As described above, in the organic electroluminescence device 100 of the present invention, the first layer 121 includes at least one first layer 121 containing a hole transporting compound doped with an electron accepting compound, whereby the anode 110 is arranged. The hole injection property from the organic electroluminescent device 100 can be improved, but such an effect is remarkable when combined with the light emitting layer 130 containing the compound represented by the general formula (4). Voltage drive can be realized. As described above, the electron-accepting compound preferably has a LUMO level of −9.0 eV to −4.0 eV.

The organic electroluminescent element according to the present invention will be described in more detail with reference to the organic electroluminescent element 100 shown in FIG. In the organic electroluminescent element 100 according to the embodiment of the present invention, the substrate 101 may be, for example, a transparent glass substrate, a semiconductor substrate made of silicon or the like, or a flexible substrate such as a resin. The anode 110 is disposed on the substrate 101 and can be formed using indium tin oxide (ITO), indium zinc oxide (In ₂ O ₃ —ZnO), or the like.

  As described above, the hole transport zone 120 is disposed between the anode 110 and the light emitting layer 130. As an example, a hole injection layer is formed on the anode 110 as the first layer 121 by doping the hole transporting compound with the above-described electron accepting compound. As the hole transporting compound, a known hole transporting compound such as an amine compound may be used.

  A hole transport layer is formed as the third layer 123 on the light emitting layer 130 side of the hole injection layer 121 using a material containing a hole transport material represented by the general formula (3). In addition, a plurality of hole transport layers 123 may be stacked. In that case, the hole transport layer disposed on the hole injection layer 121 side may include the above-described electron accepting compound.

  An intermediate layer is formed as the second layer 125 on the light emitting layer 130 side of the hole transport layer 123 using a material containing a hole transport material represented by the general formula (1). The intermediate layer 125 is formed adjacent to the light emitting layer 130. Accordingly, the electron-accepting compound contained in the hole injection layer 121 and / or the hole transport layer 123 is prevented from diffusing into the light emitting layer 130, and from the electrons that are not consumed in the light emitting layer 130, the hole transport property is increased. Thus, the excited state energy generated in the light emitting layer 130 can be prevented from diffusing into the hole transporting stacked structure. Therefore, the luminous efficiency and lifetime of the organic electroluminescent element can be improved.

  A light emitting layer 130 is formed adjacent to the intermediate layer 125. As a host material of the light emitting layer 130, for example, an anthracene derivative represented by the general formula (4) may be used. The light emitting layer 130 includes a known P-type dopant such as 2,5,8,11-Tetra-t-butylperylene (TBP), and is not particularly limited in the present invention.

On the light emitting layer 130, the electron carrying layer 140 is formed using the material containing Tris (8-hydroxyquinolinato) aluminum (Alq3), for example. On the electron transport layer 140, for example, an electron injection layer 150 is formed using a material containing lithium fluoride, lithium 8-quinolinate, or the like. On the electron injection layer 150, for example, a cathode 160 is formed using a metal such as Al or Ag, or a transparent material such as indium tin oxide (ITO) or indium zinc oxide (In ₂ O ₃ —ZnO). Is done. Each of the above layers can be formed by selecting an appropriate film formation method according to the material such as vacuum deposition, sputtering, and various coatings.

  In the organic electroluminescent element according to the present embodiment, the above-described material for an organic electroluminescent element according to the present invention can be applied to an active matrix organic EL light emitting device using a TFT.

  Further, in the organic electroluminescence device 100 according to the present embodiment, the combination of the layer structure and the material described above protects the hole transporting stacked structure from the electrons that are not consumed in the light emitting layer 130, and the light emitting layer. It is possible to prevent the excited state energy generated at 130 from diffusing into the hole-transporting laminated structure, and to adjust the charge balance of the entire organic electroluminescent device 100. In addition, by disposing the intermediate layer 125 on the light emitting layer 130 side, it is possible to suppress the electron accepting compound from diffusing into the light emitting layer 130, and to improve the light emission efficiency and life of the organic electroluminescence element.

(Production method)
The organic electroluminescent element of an Example was formed using the material mentioned above. FIG. 2 is a schematic view showing an organic electroluminescence element 200 of the example. In this example, the anode 110 was formed of ITO having a thickness of 150 nm. Further, a layer having a film thickness of 10 nm is formed using DNTPD or the compound 3 shown below, and the compound 1 shown below as an electron-accepting compound is 3% by mass with respect to the total mass of the material constituting the layer. Thus, HTL1 was formed as a hole injecting / transporting layer 221 by doping. Further, using the compound 2-1 as the compound represented by the general formula (3), a layer with a thickness of 10 nm was formed, and HTL2 was formed as the hole transport layer 223. Further, using the compound 1-2 or the compound 1-18 as the compound represented by the general formula (1), an HTL3 having a thickness of 10 nm was formed to form an intermediate layer 225.

  Subsequently, as a compound represented by the general formula (4), a host material containing 9,10-Di (2-naphthyl) anthracene (ADN) is added to 2,5,8,11-Tetra-t-butylperylene (TBP). 3% was doped to form a light emitting layer 130 having a thickness of 25 nm. An electron transport layer 140 having a thickness of 25 nm was formed from Alq3, an electron injection layer 150 having a thickness of 1 nm was formed from LiF, and a cathode 116 having a thickness of 100 nm was formed from Al.

In addition, as a comparative example, an organic electroluminescence element was produced using the compound 2 shown below in addition to the above compounds for HTL1 to HTL3.

Table 1 summarizes the combinations of the compounds used in HTL1 to HTL3 of the produced organic electroluminescence elements.

About the organic electroluminescent element of the produced Example and a comparative example, voltage, lifetime, and luminous efficiency were evaluated. The current density was 10 mA / cm ² . The evaluation results are shown in Table 2. The lifetime and luminous efficiency are shown as relative ratios, assuming that the lifetime and luminous efficiency of the organic electroluminescence device of Comparative Example 1 is 1.

  As is apparent from Table 2, Example 1 of the present invention improves the device life and efficiency as the drive voltage decreases, as compared with Comparative Example 1 (Patent Document 1) in which DNTPD is not doped with Compound 1. The effect was recognized. In addition, even when the electron accepting compound was doped into the compound 3 which is a non-carbazole-based hole transport material (Example 2), the effect of improving the light emission efficiency and the device lifetime was recognized. Further, even when the compound 1-18 was used for the intermediate layer HTL3 (Example 3), the effect of improving the light emission efficiency and the device lifetime was recognized. When Example 1 of the present invention was compared with the case where the compounds contained in the hole transport layer HTL2 and the intermediate layer HTL3 were replaced (Comparative Example 2), a decrease in driving voltage and an improvement in luminous efficiency and lifetime were observed. . In addition, when Example 1 and Example 3 of the present invention are compared with a case where a compound that is a non-benzophenone and benzothiophene-based hole transport material is used for HTL3 (Comparative Example 3), a decrease in driving voltage and luminous efficiency are also obtained. Improved lifespan was observed.

  As described above, in the organic electroluminescence device of the present invention, in the laminated structure of three or more layers having different film compositions arranged in the hole transport zone, a layer containing a hole transport compound doped with an electron accepting compound on the anode side High efficiency by disposing at least one layer containing a compound represented by the general formula (1) on the light emitting layer side of the layer containing a hole transporting compound doped with an electron accepting compound. It can also be seen that a long-life organic electroluminescence device can be provided.

100 organic EL device, 101 substrate, 110 anode, 120 hole transport zone, 121 first layer, 123 third layer, 125 second layer, 130 light emitting layer, 140 electron transport layer, 150 electron injection layer, 160 Cathode, 200 organic EL device, 220 hole transport zone, 221 first layer, 223 third layer, 225 second layer

Claims (6)

Between the anode and the light emitting layer, it has a laminated structure of three or more layers having different film compositions,
The laminated structure is
A first layer comprising a hole transporting compound doped with an electron accepting compound;
A second layer that is disposed between the first layer and the light emitting layer and that is adjacent to the light emitting layer and includes a compound represented by the following general formula (1);
An organic electroluminescence device comprising:

[In general formula (1), Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring forming carbon number. 5 or more and 50 or less heteroaryl group, and at least one of Ar ₁ and Ar ₂ is a dibenzoheteroyl group represented by the following general formula (2), and L ₁ , L ₂ and L ₃ are each independently It is a single bond, a substituted or unsubstituted arylene group having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having 4 to 15 ring carbon atoms. In general formula (2), X is , O or S, and each R ₁ is independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 4 to 50 ring carbon atoms. , M is 0 or more and 4 or less Is an integer.
] The organic electroluminescence device according to claim 1, further comprising a third layer containing a compound represented by the following general formula (3) between the first layer and the second layer. .

[In the general formula (3), Ar ₅ , Ar ₆ and Ar ₇ are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring forming carbon atom having 5 to 50 carbon atoms. Ar ₈ is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 50 ring carbon atoms, or a substituted or unsubstituted heteroaryl group. A substituted alkyl group having 1 to 50 carbon atoms, and L ₄ is a single bond, a substituted or unsubstituted arylene group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring carbon atom having 5 to 50 carbon atoms. The following heteroarylene groups. ]   The organic electroluminescence device according to claim 1, wherein the electron-accepting compound has a LUMO level of −9.0 eV to −4.0 eV.   The organic electroluminescence device according to claim 1, wherein the first layer is disposed adjacent to the anode.   The organic light-emitting device according to claim 1, wherein the light-emitting layer includes a light-emitting material that mainly emits light through a singlet excited state. The organic light-emitting device according to claim 5, wherein the light-emitting material includes a compound represented by the following general formula (4).

[In the general formula (4), Ar ₉ is independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted ring forming carbon number of 3 to 50 carbon atoms. A cycloalkyl group, a substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 50 ring carbon atoms. Group, substituted or unsubstituted arylthio group having 6 to 50 ring carbon atoms, substituted or unsubstituted alkoxycarbonyl group having 2 to 50 carbon atoms, substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms Group, substituted or unsubstituted heteroaryl group having 5 to 50 carbon atoms in ring formation, substituted or unsubstituted silyl group, carboxyl group, halogen An atom, a cyano group, a nitro group, or a hydroxyl group, and n is an integer of 1-10. ]