JP2016111065A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent element in which a luminous efficiency and an emission lifetime are improved.SOLUTION: An organic electroluminescent element 100 comprises: a positive electrode 120; an anode side hole transport layer 131; an intermediate hole transport layer 133; a luminescent layer side hole transport layer 135; and a luminescent layer 140, in sequence, and the luminescent layer side hole transport layer 135 includes a chemical compound expressed by the general formula (1) below.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an organic electroluminescent device.

  In recent years, development of an organic electroluminescence display (Organic Electroluminescence Display) has been promoted. In addition, organic electroluminescence devices, which are self-luminous light emitting devices used in organic electroluminescence display devices, are also being actively developed.

  Here, as a structure of the organic electroluminescent element, for example, a laminated structure in which an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode are laminated in order is known.

  In such an organic electroluminescent element, holes and electrons injected from the anode and the cathode recombine in the light emitting layer to generate excitons. Furthermore, light is emitted by the generated excitons transitioning to the ground state.

  For example, Patent Documents 1 to 5 disclose techniques related to a hole transport material or a hole transport layer in an organic electroluminescent element. Specifically, Patent Document 1 discloses a hole transport material containing a carbazolyl group that can be used for a hole transport layer. Patent Document 2 discloses a technique for adding an electron-accepting material to a hole transport layer or the like. Furthermore, Patent Documents 3 to 5 disclose techniques for forming a hole transport layer with a multilayer structure of a plurality of layers.

JP 2002-241352 A International Publication No. 2007/105906 Korean Published Patent No. 2013-0007159 JP 2011-187959 A International Publication No. 2014/034791

  However, in the techniques disclosed in Patent Documents 1 to 5, satisfactory values have not been obtained for the light emission efficiency and the light emission lifetime of the organic electroluminescent elements, and further improvements are necessary.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved organic electroluminescence device having improved luminous efficiency and luminous lifetime. .

  In order to solve the above problems, according to an aspect of the present invention, an anode, a light emitting layer, and an anode-side hole transport material provided between the anode and the light emitting layer, the electron accepting material is doped. An anode-side hole transport layer, an anode-side hole transport layer and a light-emitting layer, and an intermediate hole-transport layer containing an intermediate hole-transport material; A light-emitting layer-side hole transport layer provided adjacent to the light-emitting layer, the light-emitting layer-side hole transport layer including a light-emitting layer-side hole transport material represented by the following general formula (1) An organic electroluminescent device is provided.

In General Formula (1), Ar _{1 to} Ar ₂ are a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 50 ring carbon atoms. R _{1 to} R ₃ each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, a substituted or unsubstituted ring; A heterocyclic group having 3 to 50 atoms or a ring formed by adjacent R _{1 to} R ₃ , m is an integer of 0 or more and 4 or less, and p and q are integers of 0 or more and 5 or less. L ₁ 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 5 to 15 ring carbon atoms, a carbon atom a, b separated from each other Or are directly connected through a single bond.

  According to this viewpoint, the light emission efficiency and light emission lifetime of the organic electroluminescent element can be improved.

  Here, the intermediate hole transport material may be a compound represented by the following general formula (2).

In the general formula (2), Ar _{1 to} Ar ₃ are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring group having 5 to 50 ring carbon atoms. The following heteroaryl groups, Ar ₄ is a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, a substituted or unsubstituted ring carbon number of 5 or more A heteroaryl group having 50 or less, or a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, and L ₁ 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 5 to 15 ring carbon atoms.

  According to this viewpoint, the light emission efficiency and light emission lifetime of the organic electroluminescent element can be improved.

  Further, the electron-accepting material may have a LUMO (Lowest Unoccupied Molecular Orbital) level of −9.0 eV to −4.0 eV.

  According to this viewpoint, the light emission efficiency and light emission lifetime of the organic electroluminescent element can be improved.

  The anode side hole transport layer may be adjacent to the anode.

  According to this viewpoint, the light emission efficiency and light emission lifetime of the organic electroluminescent element can be improved.

  The anode side hole transport material may be a compound represented by the general formula (2).

  According to this viewpoint, the light emission efficiency and light emission lifetime of the organic electroluminescent element can be improved.

  Moreover, the light emitting layer may contain the compound represented by following General formula (3).

In the general formula (3), Ar ₁ is independently of each other a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted ring carbon number of 3 or more. A cycloalkyl group having 50 or less, 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 ring structure having 6 to 50 carbon atoms An aryloxy group, 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 ring carbon number of 6 to 50 The following aryl groups, substituted or unsubstituted heteroaryl groups having 5 to 50 ring atoms, substituted or unsubstituted silyl groups, A sil group, a halogen atom, a cyano group, a nitro group, or a hydroxyl group, and n is an integer of 1-10.

  According to this viewpoint, the light emission efficiency and light emission lifetime of the organic electroluminescent element can be improved.

  As described above, according to the present invention, the anode-side hole transport layer, the intermediate hole-transport layer, and the light-emitting layer-side hole transport layer are provided between the anode and the light-emitting layer. Luminous efficiency and luminous lifetime can be improved.

It is explanatory drawing which shows schematic structure of the organic electroluminescent element which concerns on one Embodiment of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. Configuration of organic electroluminescent element>
(1-1. Overall configuration)
First, based on FIG. 1, the whole structure of the organic electroluminescent element 100 which concerns on one Embodiment of this invention is demonstrated.

  As shown in FIG. 1, the organic electroluminescent device 100 according to the present embodiment includes a substrate 110, a first electrode 120 disposed on the substrate 110, and a hole transport layer 130 disposed on the first electrode 120. A light emitting layer 140 disposed on the hole transport layer 130, an electron transport layer 150 disposed on the light emitting layer 140, an electron injection layer 160 disposed on the electron transport layer 150, and an electron injection layer 160. A second electrode 170 disposed thereon. Here, the hole transport layer 130 is formed in a multilayer structure including a plurality of layers 131, 133, and 135.

(1-2. Configuration of substrate)
As the substrate 110, a substrate used in a general organic electroluminescence device can be used. For example, the substrate 110 may be a glass substrate, a semiconductor substrate, a transparent plastic substrate, or the like.

(1-3. Configuration of first electrode)
The first electrode 120 is, for example, an anode, and is formed on the substrate 110 using an evaporation method, a sputtering method, or the like. Specifically, the first electrode 120 is formed as a transmission electrode using a metal, an alloy, a conductive compound, or the like having a high work function. For example, the first electrode 120 is made of indium tin oxide (In ₂ O ₃ —SnO ₂ : ITO), indium zinc oxide (In ₂ O ₃ —ZnO), tin oxide (SnO ₂ ), oxide, which are excellent in transparency and conductivity. It may be formed of zinc (ZnO) or the like. The first electrode 120 may be formed as a reflective electrode by stacking magnesium (Mg), aluminum (Al), or the like.

(1-4. Configuration of hole transport layer)
The hole transport layer 130 is a layer that includes a hole transport material and has a function of transporting holes. The hole transport layer 130 is formed on the first electrode 120 with a film thickness of about 10 nm to about 150 nm (total film thickness of the stacked structure), for example.

  Here, the hole transport layer 130 of the organic electroluminescent device 100 according to the present embodiment includes the anode side hole transport layer 131, the intermediate hole transport layer 133, and the light emitting layer side hole transport from the first electrode 120 side. It is formed of a plurality of layers stacked in the order of the layer 135. In addition, the ratio of the film thickness of these layers is not specifically limited.

(1-4-1. Configuration of anode-side hole transport layer)
The anode side hole transport layer 131 is a layer containing an anode side hole transport material and further doped with an electron accepting material. For example, the anode side hole transport layer 131 is formed on the first electrode 120.

  The anode-side hole transport layer 131 can improve the hole injection property from the first electrode 120 by being doped with an electron-accepting material. Therefore, the anode side hole transport layer 131 is preferably provided in the vicinity of the first electrode 120, and more preferably provided adjacent to the first electrode 120.

  Any known hole transport material can be used as the anode side hole transport material included in the anode side hole transport layer 131. Specific examples of the anode-side hole transport material contained in the anode-side hole transport layer 131 include 1,1-bis [(di-4-tolylamino) phenyl] cyclohexane (TAPC), N-phenylcarbazole (N-phenyl). carbazole derivatives such as carbazole and polyvinyl carbazole, N, N′-bis (3-methylphenyl) -N, N′-diphenyl- [1,1-biphenyl] -4,4′-diamine (TPD) ), 4,4 ′, 4 ″ -tris (N-carbazolyl) triphenylamine (TCTA), N, N′-di (1-naphthyl) -N, N′-diphenylbenzidine (NPB), and the like. be able to.

  Any electron-accepting material can be used as the electron-accepting material contained in the anode-side hole transport layer 131 as long as it is a known electron-accepting material. However, the electron-accepting material included in the anode-side hole transport layer 131 preferably has a LUMO level of −9.0 eV or more and −4.0 eV or less, and a LUMO of −6.0 eV or more and −4.0 eV or less. It is more preferable to have a level.

  Here, specific examples of the electron-accepting material having an LUMO level of −9.0 eV to −4.0 eV include compounds represented by the following chemical formulas 4-1 to 4-14.

In the above chemical formulas 4-1 to 4-14,
R is a hydrogen atom, deuterium atom, halogen atom, fluorinated alkyl group having 1 to 50 carbon atoms, cyano group, alkoxy group having 1 to 50 carbon atoms, alkyl group having 1 to 50 carbon atoms, ring formation An aryl group having 6 to 50 carbon atoms, or a heteroaryl group having 5 to 50 ring atoms,
Ar is an electron-withdrawing substituent or an unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 5 to 50 ring atoms,
Y is a methine group (—CH═) or a nitrogen atom (—N═),
Z is a pseudohalogen atom or a sulfur (S) atom,
n is an integer in the range of 10 or less,
X is any of the substituents represented by the following chemical formulas X1 to X7.

In the chemical formulas X1 to X7,
Ra is a hydrogen atom, a deuterium atom, a halogen atom, a fluorinated alkyl group having 1 to 50 carbon atoms, a cyano group, an alkoxy group having 1 to 50 carbon atoms, an alkyl group having 1 to 50 carbon atoms, a substituted or An unsubstituted aryl group having 6 to 50 ring carbon atoms or a substituted or unsubstituted heteroaryl group having 5 to 50 ring atoms.

  Specific examples of the substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms represented by R, Ar and Ra include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 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-terphenyl-4-yl group, p-terphenyl-3-yl group P-terphenyl-2-yl group, m-terphenyl-4-yl group, m-terphenyl-3-yl group, m-terphenyl-2-yl group, o Tolyl group, m-tolyl group, p-tolyl group, p-t-butylphenyl group, p- (2-phenylpropyl) phenyl group, 3-methyl-2-naphthyl group, 4-methyl-1-naphthyl group, Examples include 4-methyl-1-anthryl group, 4′-methylbiphenylyl group, 4 ″ -t-butyl-p-terphenyl-4-yl group, fluoranthenyl group, and fluorenyl group.

  Specific examples of the substituted or unsubstituted heteroaryl group having 5 to 50 ring atoms represented by R, Ar and Ra include 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-quinoxalinyl 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, 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 Group, 3-acridinyl group, 4-acridinyl group, 9-acridinyl group, 1,7-phenanthrolin-2-yl group, 1,7-phenanthrolin-3-yl group, 1,7-phenanthroline -4-yl group, 1,7-phenanthrolin-5-yl group, 1,7-phenanthrolin-6-yl group, 1,7-phenanthrolin-8-yl group, 1,7-phen group Nansulolin-9-yl group, 1,7-phenanthrolin-10-yl group, 1,8-phenanthrolin-2-yl group, 1,8-phenanthrolin-3-yl group, 1,8 -Phenanthrolin-4-yl group, 1,8-fur Phenanthrolin-5-yl group, 1,8-phenanthrolin-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-phenanth Rin-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-phenanthroline-7-yl group, 2,9-phenanthrolin-8-yl group, 2,9-phenanthrolin-10-yl group, 2, 8-phenanthrolin-1-yl group, 2,8-phenanthrolin-3-yl group, 2,8-phenanthrolin-4-yl group, 2,8-phenanthrolin-5-yl group, 2,8-phenanthroline-6-yl group, 2,8-phenanthrolin-7-yl group, 2,8-phenanthrolin-9-yl group, 2,8-phenanthrolin-10-yl group Group, 2,7-phenanthrolin-1-yl group, 2,7-phenanthrolin-3-yl 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-phenothiazinyl 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-furazanyl group, 2-thienyl group, 3-thie Nyl 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-3-indolyl group, 4-methyl-3-indolyl group, 2-t- Examples thereof include a butyl 1-indolyl group, a 4-t-butyl 1-indolyl group, a 2-t-butyl 3-indolyl group, and a 4-t-butyl 3-indolyl group.

  Specific examples of the substituted or unsubstituted fluorinated alkyl group having 1 to 50 carbon atoms represented by R and Ra include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, and a heptadecafluorooctane group. Perfluoroalkyl group, monofluoromethyl group, difluoromethyl group, trifluoroethyl group, tetrafluoropropyl group, octafluoropentyl group and the like.

  Specific examples of the substituted or unsubstituted alkyl group having 1 to 50 carbon atoms represented by R and Ra include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, and 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, 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-cyano Tyl 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, 2,3-trinitropropyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, 4-methylcyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-norbornyl group, 2-norbornyl group, etc. It is done.

  The substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms represented by R and Ra is a group represented by -OY. Specific examples of Y include methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, and 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-dichloro Isopropyl group, 2,3-dichloro-t-butyl group, 1,2,3-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-tri Iodopropyl 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, 2-cyanoisobutyl group, 1,2-disi Noethyl 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 and the like.

  Specific examples of the halogen atom represented by R and Ra include fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and the like.

  Here, as specific compounds of the electron-accepting material, the following compounds 4-15 and 4-16 can be exemplified. For example, the LUMO level of compound 4-15 is −4.40 eV, and the LUMO level of compound 4-16 is −5.20 eV. However, the electron-accepting material is not limited to the following compounds 4-15 and 4-16.

  The doping amount of the electron-accepting material is not particularly limited as long as the anode-side hole transport layer 131 can be doped. For example, the doping amount of the electron-accepting material may be 0.1% by mass or more and 50% by mass or less with respect to the total mass of the anode-side hole transport material included in the anode-side hole transport layer 131. Preferably, it may be 0.5 mass% or more and 5 mass% or less.

(1-4-2. Configuration of Intermediate Hole Transport Layer)
The intermediate hole transport layer 133 includes an intermediate hole transport material. The intermediate hole transport layer 133 is formed on the anode side hole transport layer 131, for example.

  As the intermediate hole transport material included in the intermediate hole transport layer 133, any known hole transport material can be used. Specifically, as the intermediate hole transport material, the hole transport material described above in the specific example for the anode side hole transport material can be used.

  However, the intermediate hole transport material is preferably a compound represented by the following general formula (2).

上記一般式（２）において、Ａｒ_１〜Ａｒ_３は、互いに独立して、置換もしくは無置換の環形成炭素数６以上５０以下のアリール基、または置換もしくは無置換の環形成炭素数５以上５０以下のヘテロアリール基である。Ａｒ_４は、水素原子、重水素原子、ハロゲン原子、置換もしくは無置換の環形成炭素数６以上５０以下のアリール基、置換もしくは無置換の環形成炭素数５以上５０以下のヘテロアリール基、または置換もしくは無置換の炭素数１以上５０以下のアルキル基である。Ｌ_１は、単結合、置換もしくは無置換の環形成炭素数６以上１８以下のアリーレン基、または置換もしくは無置換の環形成炭素数５以上１５以下のヘテロアリーレン基である。

In the general formula (2), Ar _{1 to} Ar ₃ are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring group having 5 to 50 ring carbon atoms. The following heteroaryl groups. Ar ₄ represents a hydrogen atom, a deuterium atom, a halogen atom, 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 alkyl group having 1 to 50 carbon atoms. L ₁ 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 5 to 15 ring carbon atoms.

Specific examples of Ar _{1 to} Ar ₃ include phenyl group, biphenyl group, terphenyl group, naphthyl group, anthryl group, phenanthryl group, fluorenyl group, indenyl group, pyrenyl group, acetonaphthenyl group, 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, dibenzo A furanyl group, a dibenzothienyl group, etc. can be mentioned. Preferable specific examples of Ar _{1 to} Ar ₃ include a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a carbazolyl group, and a dibenzofuranyl group.

Specific examples of Ar ₄ include phenyl group, biphenyl group, terphenyl group, naphthyl group, anthryl group, phenanthryl group, fluorenyl group, indenyl group, pyrenyl group, acetonaphthenyl group, fluoranthenyl group, triphenylenyl group, pyridyl group, Furanyl, pyranyl, thienyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, benzoxazolyl, benzothiazolyl, quinoxalyl, benzimidazolyl, pyrazolyl, dibenzofuranyl , Dibenzothienyl group, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group and the like. Preferable specific examples of Ar ₄ include a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a methyl group, and an ethyl group.

Specific examples other than the single bond of L ₁ include phenylene group, biphenylylene group, terphenylene group, naphthylene group, anthrylene group, phenanthrylene group, fluorenylene group, indenylene group, pyrenylene group, acetonaphthenylene group, fluoranthenylene group, Triphenylenylene group, pyridylene group, furanylene group, pyranylene group, thienylene group, quinolylene group, isoquinolylene group, benzofuranylene group, benzothienylene group, indolylene group, carbazolylene group, benzoxazolylene group, benzothiazolylene group, quinoxarylene group, Benzimidazolylene group, pyrazolylene group, dibenzofuranylene group, dibenzothienylene group and the like can be mentioned. L ₁ may preferably be a single bond, a phenylene group, a biphenylylene group, a terphenylene group, a fluorenylene group, a carbazolylene group, or a dibenzofuranylene group.

  Specific examples of the compound represented by the general formula (2) include the following compounds 2-1 to 2-16. However, the compound represented by the general formula (2) is not limited to the following compounds 2-1 to 2-16.

  The intermediate hole transport layer 133 includes the compound represented by the above general formula (2) as an intermediate hole transport material, thereby improving the hole transport property of the hole transport layer 130, and an organic electroluminescent element. The luminous efficiency of 100 can be improved.

  In addition, the compound represented by General formula (2) may be contained in the anode side hole transport layer 131 as an anode side hole transport material. When the anode side hole transport layer 131 contains the compound represented by the general formula (2) as the anode side hole transport material, the hole transport property of the hole transport layer 130 is improved, and the organic electroluminescent element 100 Since luminous efficiency improves, it is more preferable.

  In particular, in the hole transport layer 130, when the proportion of the carbazole derivative such as the compound represented by the general formula (2) in the hole transport layer 130 is high, the light emission lifetime of the organic electroluminescent element 100 is improved. More preferred.

  In addition to the compound represented by the general formula (2), the anode-side hole transport layer 131 may further include the above-described other hole-transport material as an anode-side hole transport material.

(1-4-3. Configuration of light-emitting layer side hole transport layer)
The light emitting layer side hole transport layer 135 contains a compound represented by the following general formula (1). The light emitting layer side hole transport layer 135 is formed on the intermediate hole transport layer 133 so as to be adjacent to the light emitting layer 140, for example.

In general formula (1), in general formula (1), Ar _{1 to} Ar ₂ are substituted or unsubstituted aryl groups having 6 to 50 ring carbon atoms, or substituted or unsubstituted ring carbon atoms having 5 or more rings. 50 or less heteroaryl groups.

R _{1 to} R ₃ each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring atom. It is a ring formed by a heterocyclic group of several 3 to 50 or adjacent R _{1 to} R ₃ .

m is an integer of 0 or more and 4 or less, p and q are integers of 0 or more and 5 or less, L ₁ is a single bond, a substituted or unsubstituted arylene group having 6 to 18 ring carbon atoms, or a substituted or It is an unsubstituted heteroarylene group having 5 to 15 carbon atoms in the ring formation, and the carbon atoms a and b are separated from each other or directly bonded through a single bond.

Specific examples of Ar _{1 to} Ar ₂ include phenyl group, biphenyl group, terphenyl group, naphthyl group, anthryl group, phenanthryl group, fluorenyl group, indenyl group, pyrenyl group, acetonaphthenyl group, 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, dibenzo A furanyl group, a dibenzothienyl group, etc. can be mentioned. Preferable specific examples of Ar _{1 to} Ar ₂ include a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a carbazolyl group, and a dibenzofuranyl group.

Specific examples of R _{1 to} R ₃ include the same examples as the specific examples of Ar _{1 to} Ar ₂ , methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, isobutyl group, t -Butyl group, cyclobutyl group, pentyl group, isopentyl group, neopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, heptyl group, cycloheptyl group, octyl group, nonyl group, decyl group and the like can be mentioned.

As the substituent for the _Ar 1 to Ar ₂ and _R 1 to R _3, alkyl group, alkoxy group, aryl group, and a heteroaryl group. Examples of the aryl group and heteroaryl group are the same as those described above. Examples of the alkyl group, aryl group, and heteroaryl group are the same as those described above. Specific examples of the alkoxy group include those obtained by replacing the alkyl group described above with an alkoxy group.

Specific examples other than the single bond of L ₁ include those in which Ar _{1 to} Ar ₂ described above are divalent substituents. For example, specific examples other than the single bond of L ₁ include 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. Preferably, a phenylene group, a terphenylene group, a fluorenediyl group, a carbazolediyl group, a dibenzofurandiyl group, and the like can be given.

  The following compounds 1 to 12 can be exemplified as specific examples of the compound represented by the general formula (1). However, the compound represented by the general formula (1) is not limited to the following compounds 1 to 12.

  The light-emitting layer-side hole transport layer 135 contains a compound represented by the general formula (1) as a light-emitting layer-side hole transport material, thereby transporting holes from electrons not consumed in the light-emitting layer 140. Layer 130 can be protected. In addition, the light emitting layer side hole transport layer 135 contains the compound represented by the general formula (1), so that the excited state energy generated in the light emitting layer 140 is diffused into the hole transport layer 130. Can be prevented. Therefore, according to this configuration, the light emitting layer side hole transport layer 135 can improve the current-carrying durability of the hole transport layer 130.

  The light emitting layer side hole transport layer 135 is preferably formed in the vicinity of the light emitting layer 140 in order to more effectively prevent diffusion of electrons and energy from the light emitting layer 140. More preferably, they are formed adjacent to each other.

  In addition, the light emitting layer side hole transport layer 135 includes the compound represented by the above general formula (1), thereby adjusting the charge balance of the entire organic electroluminescent device 100, and the anode side hole transport layer. It is possible to prevent the electron-accepting material doped in 131 from diffusing into the light emitting layer 140. Thereby, the light emitting layer side hole transport layer 135 can improve the charge transport property of the hole transport layer 130.

  Therefore, the light emitting layer side hole transport layer 135 can improve the charge transport property and the current-carrying durability of the hole transport layer 130 by including the compound represented by the general formula (1). The light emission efficiency and light emission lifetime of the organic electroluminescent device 100 can be improved.

  As described above, the hole transport layer 130 including the anode-side hole transport layer 131, the intermediate hole transport layer 133, and the light-emitting layer side hole transport layer 135 is used in the current-carrying durability of the organic electroluminescent element 100. In addition, hole transport properties can be improved. Therefore, in the organic electroluminescent element 100 according to the present embodiment, the light emission efficiency and the light emission lifetime are improved.

(1-5. Configuration of light emitting layer)
The light emitting layer 140 includes a host material and a dopant material that is a light emitting material, and emits light by fluorescence, phosphorescence, or the like. The light emitting layer 140 is formed with a film thickness of about 10 nm to about 60 nm on the hole transport layer 130, for example.

  As the host material and the dopant material included in the light emitting layer 140, any known host material and dopant material can be used. For example, the light-emitting layer 140 may include a fluoranthene derivative, pyrene (and a derivative thereof), an arylacetylene derivative, a fluorene derivative, a perylene (and a derivative thereof), a chrysene derivative, or a styryl derivative as a host material or a dopant material. More specifically, the light-emitting layer 140 includes tris (8-quinolinolato) aluminum (Alq3), 4,4′-N, N′-dicavazole-biphenyl (CBP), poly (n-vinylcarbazole) (PVK), 4,4 ′, 4 ″ -tris (N-carbazolyl) triphenylamine (TCTA), 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBI), 3-tert-butyl- 9,10-di (naphth-2-yl) anthracene (TBADN), distyrylarylene (DSA), 4,4′-bis (9-carbazole) -2,2′-dimethyl-biphenyl (dmCBP), bis ( 2,2-diphenylvinyl) -1,1′-biphenyl (DPVBi), 1,4-bis (2- (3-N-ethylcarbazolyl) vinyl) ben (BCzVB), 4- (di-p-tolylamino) -4 ′-((di-p-tolylamino) styryl) stilbene (DPAVB), N- (4-((E) -2- (6-(( E) -4- (Diphenylamino) styryl) naphthalen-2-yl) vinyl) phenyl) -N-phenylbenzenamine (N-BDAVBi), 2,5,8,11-tetra-t-butylperylene (TBPe) 1,1-dipylene, 1,4-dipyrenylbenzene, 1,4-bis (N, N-diphenylamino) pyrene and the like may be included as a host material or a dopant material.

  Moreover, it is more preferable that the light emitting layer 140 contains the compound represented by following General formula (3).

上記一般式（３）において、Ａｒ_１は、互いに独立して、水素原子、重水素原子、置換もしくは無置換の炭素数１以上５０以下のアルキル基、置換もしくは無置換の環形成炭素数３以上５０以下のシクロアルキル基、置換もしくは無置換の炭素数１以上５０以下のアルコキシ基、置換もしくは無置換の炭素数７以上５０以下のアラルキル基、置換もしくは無置換の環形成炭素数６以上５０以下のアリールオキシ基、置換もしくは無置換の環形成炭素数６以上５０以下のアリールチオ基、置換もしくは無置換の炭素数２以上５０以下のアルコキシカルボニル基、置換もしくは無置換の環形成炭素数６以上５０以下のアリール基、置換もしくは無置換の環形成原子数５以上５０以下のヘテロアリール基、置換もしくは無置換のシリル基、カルボキシル基、ハロゲン原子、シアノ基、ニトロ基、またはヒドロキシル基である。ｎは、１以上１０以下の整数である。

In the general formula (3), Ar ₁ is independently of each other a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted ring carbon number of 3 or more. A cycloalkyl group having 50 or less, 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 ring structure having 6 to 50 carbon atoms An aryloxy group, 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 ring carbon number of 6 to 50 The following aryl groups, substituted or unsubstituted heteroaryl groups having 5 to 50 ring atoms, substituted or unsubstituted silyl groups, A sil group, a halogen atom, a cyano group, a nitro group, or a hydroxyl group; n is an integer of 1 or more and 10 or less.

  Moreover, the following compounds 3-1 to 3-12 can be illustrated as a specific example of a compound represented by General formula (3). However, the compound represented by the general formula (3) is not limited to the following compounds 3-1 to 3-12.

  When the light emitting layer 140 contains the compound represented by General formula (3), the anode side hole transport layer 131 can improve the hole injection property from the 1st electrode 120 more notably. Therefore, the light emitting layer 140 can further improve the light emission efficiency and the light emission lifetime of the organic electroluminescent element 100 by including the compound represented by the general formula (3).

  In addition, the light emitting layer 140 may contain the compound represented by General formula (3) as a host material, and may contain it as a dopant material.

  The light emitting layer 140 may be formed as a layer that emits light of a specific color. For example, the light emitting layer 140 may be formed as a red light emitting layer, a green light emitting layer, or a blue light emitting layer.

  When the light emitting layer 140 is a blue light emitting layer, a known blue dopant can be used. For example, as blue dopant, perylene and its derivatives, iridium (Ir) complexes such as bis [2- (4,6-difluorophenyl) pyridinate] picolinate iridium (III) (FIrpic), etc. may be used. it can.

Moreover, when the light emitting layer 140 is a red light emitting layer, a well-known red dopant can be used. For example, as red dopants, rubrene and its derivatives, 4-dicyanomethylene-2- (p-dimethylaminostyryl) -6-methyl-4H-pyran (DCM) and its derivatives, bis (1-phenylisoquinoline) An iridium complex such as (acetylacetonate) iridium (III) (Ir (piq) ₂ (acac)), an osmium (Os) complex, a platinum complex, or the like can be used.

Furthermore, when the light emitting layer 140 is a green light emitting layer, a known green dopant can be used. For example, coumarin and its derivatives, iridium complexes such as tris (2-phenylpyridine) iridium (III) (Ir (ppy) ₃ ), and the like can be used.

(1-6. Configuration of electron transport layer)
The electron transport layer 150 is a layer that includes an electron transport material and has a function of transporting electrons. The electron transport layer 150 is formed on the light emitting layer 140 with a film thickness of about 15 nm to about 50 nm, for example. Any electron transporting material contained in the electron transporting layer 150 can be used as long as it is a known electron transporting material. Specific examples of the electron transport material include, for example, quinoline derivatives such as tris (8-quinolinolato) aluminum (Alq3), 1,2,4-triazole derivatives (TAZ), bis (2-methyl-8-quinolinolato)-( Examples include materials having a nitrogen-containing aromatic ring, such as Li complexes such as p-phenylphenolate) -aluminum (BAlq), beryllium bis (benzoquinoline-10-olate) (BeBq2), and lithium quinolate (LiQ). Here, examples of the material having a nitrogen-containing aromatic ring include materials containing a pyridine ring such as 1,3,5-tri ((3-pyridyl) -phen-3-yl) benzene, A material containing a triazine ring such as 6-tris (3 ′-(pyridin-3-yl) biphenyl-3-yl) -1,3,5-triazine, 2- (4- (N-phenylbenzimidazolyl-1-) And a material containing an imidazole derivative such as (Ilphenyl) -9,10-dinaphthylanthracene.

(1-7. Configuration of electron injection layer)
The electron injection layer 160 is a layer having a function of facilitating injection of electrons from the second electrode 170. The electron injection layer 160 is formed with a film thickness of about 0.3 nm to about 9 nm on the electron transport layer 150, for example. The electron injection layer 160 may be formed using any material known as a material for forming the electron injection layer 160. Specific examples of the material for forming the electron injection layer 160 include lithium fluoride (LiF), sodium chloride (NaCl), cesium fluoride (CsF), lithium oxide (Li ₂ O), barium oxide (BaO), and lithium quino. Rate (LiQ) and the like.

(1-8. Configuration of second electrode)
The second electrode 170 is, for example, a cathode (cathode), and is formed on the electron injection layer 160 by using a vapor deposition method, a sputtering method, or the like. Specifically, the second electrode 170 is formed as a reflective electrode using a metal, an alloy, a conductive compound, or the like having a low work function. The second electrode 170 is, for example, lithium (Li), magnesium (Mg), aluminum (Al), silver (Ag), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In). , Magnesium-silver (Mg-Ag), or the like. Further, the second electrode 170 may be formed as a transmissive electrode by using the above-described material thinned to 20 nm or less, indium tin oxide (ITO), indium zinc oxide (IZO), or the like.

(1-9. Modified example of organic electroluminescence device)
The structure of the organic electroluminescent element 100 shown in FIG. 1 is merely an example, and the organic electroluminescent element 100 according to the present embodiment is not limited to the structure of FIG. In the organic electroluminescent element 100 according to this embodiment, a part of the layers may be further formed of a plurality of layers, and other layers may be added. In addition, the organic electroluminescent element 100 according to the present embodiment may not include at least one of the electron transport layer 150 and the electron injection layer 160.

  In addition, the organic electroluminescent device 100 according to the present embodiment may include a hole injection layer between the first electrode 120 and the hole transport layer 130.

  The hole injection layer is a layer having a function of facilitating injection of holes from the first electrode 120. The hole injection layer is formed with a film thickness of about 10 nm to about 150 nm on the first electrode 120, for example. The hole injection layer may be formed using any material known as a material for forming the hole injection layer. Specific examples of the material for forming the hole injection layer include triphenylamine-containing polyether ketone (TPAPEK), 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate (PPBI), N, N ′. -Diphenyl-N, N'-bis- [4- (phenyl-m-tolyl-amino) -phenyl] -biphenyl-4,4'-diamine (DNTPD), phthalocyanine compounds such as copper phthalocyanine, 4,4 ', 4 ″ -tris (3-methylphenylphenylamino) triphenylamine (m-MTDATA), N, N′-di (1-naphthyl) -N, N′-diphenylbenzidine (NPB), 4,4 ′, 4 ″ -tris {N, N-diphenylamino} triphenylamine (TDATA), 4,4 ′, 4 ″ -tri (N, N-2-naphthylphenylamino) triphenylamine (2-TNATA), polyaniline / dodecylbenzenesulfonic acid (Pani / DBSA), poly (3,4-ethylenedioxythiophene) / poly (4-styrenesulfonate) ) (PEDOT / PSS), polyaniline / camphorsulfonic acid (Pani / CSA), or polyaniline / poly (4-styrenesulfonate) (PANI / PSS).

(1-9. Manufacturing method of organic electroluminescence device)
Each layer of the organic electroluminescent element 100 according to the present embodiment described above can be formed by selecting an appropriate film forming method according to the material such as vacuum deposition, sputtering, and various coating methods.

  For example, the metal layers such as the first electrode 120, the second electrode 170, and the electron injection layer 160 may be formed by using an electron beam evaporation method, a hot filament evaporation method, a vacuum evaporation method, or the like. , Sputtering, or plating such as electroplating and electroless plating.

  The organic layers such as the hole transport layer 130, the light emitting layer 140, and the electron transport layer 150 may be formed by, for example, physical vapor deposition (PVD) such as vacuum deposition, screen printing, or inkjet. It can be formed by a printing method such as an (ink jet) printing method, a laser transfer method, a coating method such as a spin coat method, or the like.

  The example of the organic electroluminescent element 100 according to the present embodiment has been described in detail above.

  Hereinafter, the organic electroluminescent element according to this embodiment will be described in detail with reference to Examples and Comparative Examples. In addition, the Example shown below is an example to the last, and the organic electroluminescent element which concerns on this embodiment is not limited to the following example.

(Synthesis of compounds)
(Synthesis Example 1: Synthesis of Compound 1)
Compound 1 was synthesized according to the following reaction scheme.

(Synthesis of Compound A)
Under an Ar atmosphere, 53.8 g of N- [1,1′-biphenyl] -4-yl-N- (4-bromophenyl)-[1,1′-biphenyl] -4-amine in a 2 L flask, Pd (Dppf) Cl ₂ .CH ₂ Cl ₂ ([1,1′-bis (diphenylphosphino) ferrocene] dichloropalladium.CH ₂ Cl ₂ ) 6.46 g, KOAc (potassium acetate) 33.3 g, and Bis 33.0 g of (pinacolato) diboron was added, and the mixture was stirred at 100 ° C. for 12 hours after vacuum degassing in 750 mL of Dioxane. Thereafter, the solvent was distilled off, CH ₂ Cl ₂ and water were added, the organic phase was separated, magnesium sulfate and activated clay were added, and suction filtration was performed to distill off the solvent. The obtained crude product was purified by silica gel column chromatography (using a mixed solvent of dichloromethane and hexane) to obtain 56.8 g (yield 98%) of Compound A as a white solid. _{(FAB-MS: C 36 H} 34 BNO 2, measured value 523)

(Synthesis of Compound 1)
In a 200 mL three-necked flask under Ar atmosphere, 1.66 g of compound A, 1.52 g of compound B 1, 0.11 g of Pd (PPh ₃ ) ₄ (tetrakis (triphenylphosphine) palladium (0)), and 1.1 g of sodium carbonate was added, and the mixture was heated and stirred at 80 ° C. for 2 hours in a mixed solvent of 40 mL of toluene, 19 mL of EtOH, and 9.0 L of water. After air cooling, water was added to separate the organic layer, and the solvent was distilled off. The obtained crude product was purified by silica gel column chromatography (using a mixed solvent of toluene and hexane) and then recrystallized with a mixed solvent of toluene / EtOH to obtain 1.96 g (yield 84%) of Compound 1 as a white solid. )Obtained. The molecular weight of Compound 1 (C ₅₅ H ₃₉ N) measured by FAB-MS measurement was 713. ^{Also, 1 H NMR (300MHz, CDCl} 3) the chemical shift value δ of the measured compound 1, 7.82-7.76 (m, 2H), 7.62-7.56 (m, 6H,) 7.53-7.49 (m, 5H), 7.47 (d, 2H, J = 6.0 Hz), 7.45-7.39 (m, 4H), 7.37-7.29. (M, 3H), 7.27-7.18 (m, 17H). Therefore, it was confirmed that Compound 1 was synthesized.

(Synthesis Example 2: Synthesis of Compound 5)
Compound 5 was synthesized according to the following reaction scheme.

(Synthesis of Compound A)
In an Ar atmosphere, a 500 mL three-necked flask was charged with 2.32 g of 4- (4,4,5,5-tetramethyl-1,3,2-dioxabolan-2-yl) aniline, 2-Bromo-9, 4.00 g of 9-diphenylfluorene, 1.04 g of Pd (PPh ₃ ) ₄ and 2.79 g of potassium carbonate were added, and the mixture was heated and stirred at 90 ° C. for 14 hours in a mixed solvent of 200 mL toluene, water 32 mL and ethanol 12 mL. . After air cooling, water was added to separate the organic layer, and the solvent was distilled off. The obtained crude product was purified by silica gel column chromatography (using a mixed solvent of dichloromethane and hexane) and then recrystallized with a mixed solvent of ethyl acetate / hexane to obtain 2.18 g of compound A as a white solid (yield) 53%). _{(FAB-MS: C 31 H} 23 N, measured value 409)

(Synthesis of Compound 5)
In an Ar atmosphere, in a 200 mL three-necked flask, 2.11 g of compound A, 3.15 g of 3-bromodibenzofuran, Pd ₂ (dba) ₃ .CHCl ₃ (tris (dibenzylideneacetone) dipalladium · CHCl ₃ ) 0.384 g and 2.06 g of t-BuONa were added, 65 mL of dehydrated toluene and 0.56 mL of 2M (t-Bu) ₃ P / dehydrated toluene were added, and the mixture was stirred for 7 hours while heating under reflux. After air cooling, water was added to separate the organic layer, and the solvent was distilled off. The obtained crude product was purified by silica gel column chromatography (using a mixed solvent of dichloromethane and hexane) and then recrystallized with a mixed solvent of methylene chloride / ethanol to obtain 3.30 g of compound 5 as a white solid (yield 62 %)Obtained. The molecular weight of Compound 5 (C ₅₅ H ₃₅ NO ₂ ) measured by FAB-MS measurement was 741. The chemical shift value δ of compound 5 measured by ¹ H NMR (300 MHz, CDCl ₃ ) is 7.87 (dd, 2H), 7.81 (d, 2H), 7.80 (dd, 2H). 7.54-7.46 (4H), 7.46-7.13 (25H). Therefore, it was confirmed that compound 5 was synthesized.

(Production of organic electroluminescence device)
The organic electroluminescent element according to this embodiment was produced by the following production method.

First, a surface treatment with ultraviolet ozone (O ₃ ) was performed on an ITO-glass substrate that had been patterned and cleaned in advance. The film thickness of the ITO film (first electrode) on the glass substrate was 150 nm. After the ozone treatment, the surface-treated substrate was put into a glass bell jar type vapor deposition apparatus for forming an organic layer, and an anode side hole transport layer, an intermediate layer at a vacuum degree of 10 ⁻⁴ to 10 ⁻⁵ Pa. A hole transport layer, a light emitting layer side hole transport layer, a light emitting layer, and an electron transport layer were sequentially deposited. The film thicknesses of the anode-side hole transport layer, the intermediate hole-transport layer, and the light-emitting layer-side hole transport layer were each 10 nm. The thickness of the light emitting layer was 25 nm, and the thickness of the electron transport layer was 25 nm. Then, the board | substrate was moved to the glass bell jar type vapor deposition machine for metal film-forming, and the electron injection layer and the 2nd electrode were vapor-deposited by the vacuum degree of 10 ^{< -4} > ^-10 < ^-5 > Pa. The thickness of the electron injection layer was 1 nm, and the thickness of the second electrode was 100 nm.

  Here, the anode-side hole transport layer, the intermediate hole-transport layer, and the light-emitting layer-side hole transport layer correspond to a hole-transport layer having a stacked structure. The anode-side hole transport layer, the intermediate hole-transport layer, and the light-emitting layer-side hole transport layer were produced using the materials shown in Table 1 below for each of Examples and Comparative Examples.

  In Table 1, for example, “compound 2-3, 4-15” means that compound 2-3, which is an anode-side hole transport material, is doped with compound 4-15, which is an electron-accepting material. To do. The doping amount of the electron-accepting material was 3% by mass with respect to the mass of the anode-side hole transport material.

  In Table 1, compounds 6-1, 6-2, and 6-3 mean general hole transport materials represented by the following chemical formulas.

  As the host material of the light emitting layer, 9,10-di (2-naphthyl) anthracene (ADN, compound 3-2) is used, and as the dopant material, 2,5,8,11-tetra-t-butylperylene ( TBP) was used. In addition, 3 mass% of dopant materials were added with respect to the mass of host material. Further, the electron transport layer was formed of Alq3, the electron injection layer was formed of LiF, and the second electrode was formed of aluminum (Al).

(2-2. Evaluation results)
Next, the driving voltage, luminous efficiency, and half life of the produced organic electroluminescent element were evaluated. The evaluation results are shown in Table 2 below. In addition, the drive voltage and luminous efficiency of each Example and Comparative Example are measured values at a current density of 10 mA / cm ² . The half life is a result of measurement using 1000 cd / m ² as the initial luminance.

  The measurement was performed using a 2400 series source meter manufactured by Keithley Instruments, a color luminance meter CS-200 (manufactured by Konica Minolta Holdings Co., Ltd., measuring angle 1 °), and a measurement PC program LabVIEW8. 2 (manufactured by National Instruments, Inc.) was used in a dark room.

  Referring to the results in Table 1 and Table 2, it was found that Examples 1 to 4 have improved luminous efficiency and a longer half-life than Comparative Examples 1 to 3. Therefore, by providing the anode side hole transport layer, the intermediate hole transport layer, and the light emitting layer side hole transport layer between the first electrode and the light emitting layer, the light emission efficiency and the light emission lifetime of the organic electroluminescent element are improved. It was confirmed that it improved.

  Specifically, when Example 1 was compared with Comparative Example 2, the characteristics of Example 1 were better. In Comparative Example 2, the electron-accepting material (for example, compound 4-15) is not doped in the anode side hole transport layer. Therefore, it can be seen that the anode-side hole transport layer is preferably doped with an electron-accepting material.

  Further, when Example 1 was compared with Comparative Example 1, the characteristics of Example 1 were better. In Comparative Example 1, the compounds contained in the intermediate hole transport layer and the light emitting layer side hole transport layer are replaced with those in Example 1. Therefore, it turns out that it is preferable that the light emitting layer side hole transport layer containing the compound represented by General formula (1) adjoins a light emitting layer. Moreover, it has confirmed that a remarkable difference came out in the characteristic by replacing the compounds contained in the intermediate hole transport layer and the light emitting layer side hole transport layer.

  Moreover, when Examples 1-3 were compared with Comparative Example 3, the characteristics of Examples 1-3 were better. In Comparative Example 3, the light-emitting layer-side hole transport material contained in the light-emitting layer-side hole transport layer is not a compound represented by the general formula (1), but a general hole-transport material 6-1. ing. Therefore, it turns out that it is preferable that the light emitting layer side hole transport layer contains the compound represented by General formula (1).

  Furthermore, when Examples 1 and 2 were compared with Example 3, the characteristics of Examples 1 and 2 were better. In Example 3, the anode-side hole transport material contained in the anode-side hole transport layer is not a compound represented by the general formula (2), but a general hole-transport material 6-2 containing no carbazolyl group Is used. Therefore, it turns out that it is preferable that the anode side hole transport material contained in an anode side hole transport layer is a compound represented by General formula (2).

  Further, when Examples 1 and 2 were compared with Example 4, the characteristics of Examples 1 and 2 were better. In Example 4, the intermediate hole transport material contained in the intermediate hole transport layer is not a compound represented by the general formula (2), but a general hole transport material 6-3 not containing a carbazolyl group is used. It has been. Therefore, it can be seen that the intermediate hole transport material contained in the intermediate hole transport layer is preferably a compound represented by the general formula (2).

  As described above, according to the present embodiment, the anode-side hole transport layer doped with the electron-accepting material, the intermediate hole transport layer, between the first electrode (anode) and the light emitting layer, And since the light emitting layer side hole transport layer containing the compound represented by the general formula (1) is laminated, the light emission efficiency and the light emission lifetime of the organic electroluminescence device are improved.

  This is because a light emitting layer side hole transport layer containing a compound represented by the general formula (1) is arranged so that the light emitting layer side hole transport layer is changed from electrons not consumed in the light emitting layer to the hole transport layer. This is presumably because the energy of the excited state generated in the light emitting layer is prevented from diffusing into the hole transporting layer, and the charge balance of the entire device is adjusted. Moreover, the anode side hole transport which the light emitting layer side hole transport layer provided in the vicinity of the 1st electrode (anode) by arrange | positioning the light emitting layer side hole transport layer containing the compound represented by General formula (1). This is considered to be for suppressing the diffusion of the electron-accepting material contained in the layer to the light emitting layer.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Organic electroluminescent element 110 Board | substrate 120 1st electrode 130 Hole transport layer 131 Anode side hole transport layer 133 Intermediate | middle hole transport layer 135 Light emitting layer side hole transport layer 140 Light emitting layer 150 Electron transport layer 160 Electron injection layer 170 1st 2 electrodes

Claims (6)

The anode,
A light emitting layer;
An anode-side hole transport layer that is provided between the anode and the light-emitting layer, includes an anode-side hole transport material, and is doped with an electron-accepting material;
An intermediate hole transport layer provided between the anode side hole transport layer and the light emitting layer, and including an intermediate hole transport material;
A light-emitting layer side hole transport layer provided between the intermediate hole transport layer and the light-emitting layer, and adjacent to the light-emitting layer,
The said light emitting layer side hole transport layer is an organic electroluminescent element containing the light emitting layer side hole transport material represented by following General formula (1).

In the general formula (1), Ar _{1 to} Ar ₂ are substituted or unsubstituted aryl groups having 6 to 50 ring carbon atoms, or substituted or unsubstituted heteroaryl groups having 5 to 50 ring carbon atoms. And
R _{1 to} R ₃ each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted ring atom. A ring group formed by a heterocyclic group of several 3 to 50 or adjacent R _{1 to} R ₃ ;
m is an integer from 0 to 4,
p and q are integers of 0 to 5,
L ₁ 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 5 to 15 ring carbon atoms,
The carbon atoms a and b are separated from each other or directly bonded through a single bond. The organic electroluminescent element according to claim 1, wherein the intermediate hole transport material is a compound represented by the following general formula (2).

In the above general formula (2),
Ar _{1 to} Ar ₃ are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms or a substituted or unsubstituted heteroaryl group having 5 to 50 ring carbon atoms,
Ar ₄ represents a hydrogen atom, a deuterium atom, a halogen atom, 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 alkyl group having 1 to 50 carbon atoms;
L ₁ 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 5 to 15 ring carbon atoms.   The organic electroluminescence device according to claim 1, wherein the electron-accepting material has a LUMO (Lowest Unoccupied Molecular Orbital) level of −9.0 eV to −4.0 eV.   The organic electroluminescent element according to claim 1, wherein the anode-side hole transport layer is adjacent to the anode.   The organic electroluminescent element according to any one of claims 1 to 4, wherein the anode-side hole transport material is a compound represented by the general formula (2). The said light emitting layer is an organic electroluminescent element as described in any one of Claims 1-5 containing the compound represented by following General formula (3).

In the general formula (3),
Ar ₁ is independently of each other a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, substituted Or an 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, substituted or unsubstituted A substituted or unsubstituted arylthio group having 6 to 50 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, substituted or unsubstituted Heteroaryl group having 5 to 50 substituted ring atoms, substituted or unsubstituted silyl group, carboxyl group, halogen atom, Group, nitro group, or hydroxyl group,
n is an integer of 1 or more and 10 or less.

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