JP2016108292A - Monoamine derivative and organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compound that gives an organic electroluminescent element having improved emission lifetime.SOLUTION: The monoamine derivative is represented by formula (1). [Rand Rare each independently H, a halogen atom, a substituted/unsubstituted 1-15C alkyl group, a 6-30C aryl group or a 1-30C heteroaryl group; a and b are each independently an integer of 1 to 4; and Aris a substituent of formula (2)(Arto Arare each independently an unsubstituted 6-50C aryl group; and a sum of l and m is integer of 0 to 2)]SELECTED DRAWING: Figure 1

Description

  The present invention relates to a monoamine derivative and an organic electroluminescence device.

  In recent years, organic electroluminescence (Organic Electroluminescence) display devices have been developed. For this reason, organic EL devices (Organic Electroluminescence Devices), which are self-luminous light emitting devices used in organic EL display devices, are also being actively developed.

  As a structure of the organic EL element, for example, a structure in which an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially stacked is known. In such an organic EL device, first, holes and electrons injected from the anode and the cathode recombine in the light emitting layer to generate excitons, and then the generated excitons transition to the ground state. By doing so, light emission is performed.

  Here, in order to improve the light emission lifetime of the organic EL element, various compounds have been studied as materials for each layer. For example, Patent Documents 1 and 2 disclose that an amine derivative having a dibenzothiophene ring can be used as a hole transport material of an organic EL element.

International Publication No. 2011/148909 US Patent Application Publication No. 2011/0248426

  However, the organic EL element using the amine derivative disclosed in Patent Documents 1 and 2 has a problem that the light emission lifetime is not sufficient. Therefore, there has been a demand for a material compound that can further improve the light emission lifetime of the organic EL element.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a novel monoamine derivative capable of improving the light emission lifetime of an organic EL device, and the An object of the present invention is to provide an organic EL device containing a monoamine derivative.

上記一般式（１）において、
Ｒ_１およびＲ_２は、互いに独立して、水素原子、ハロゲン原子、置換もしくは無置換の炭素数１以上１５以下のアルキル基、置換もしくは無置換の環形成炭素数６以上３０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１以上３０以下のヘテロアリール基であり、
ａおよびｂは、互いに独立して、１以上４以下の整数であり、
Ａｒ_１は、以下の一般式（２）で表される置換基であり、

上記一般式（２）において、
Ａｒ_２〜Ａｒ_４は、互いに独立して、無置換の環形成炭素数６以上５０以下のアリール基であり、
ｌおよびｍは、ｌ＋ｍが０以上２以下となる整数である。 In order to solve the above problems, according to one aspect of the present invention, a monoamine derivative represented by the following general formula (1) is provided.

In the general formula (1),
R ₁ and R ₂ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, Or a substituted or unsubstituted heteroaryl group having 1 to 30 ring carbon atoms,
a and b are each independently an integer of 1 or more and 4 or less,
Ar ₁ is a substituent represented by the following general formula (2),

In the above general formula (2),
Ar _{2 to} Ar ₄ are each independently an unsubstituted aryl group having 6 to 50 ring carbon atoms,
l and m are integers such that l + m is 0 or more and 2 or less.

  According to this viewpoint, the light emission lifetime of the organic EL element can be improved by using such a monoamine derivative.

Ar _{2 to} Ar ₄ may be each independently an unsubstituted aryl group having 6 to 14 ring carbon atoms.

  According to this viewpoint, the light emission lifetime of the organic EL element can be further improved by using such a monoamine derivative.

1 to 3 may be sufficient as the sum total of the aromatic ring which said Ar < ₂ > -Ar < ₄ > has.

  According to this viewpoint, the light emission lifetime of the organic EL element can be further improved by using such a monoamine derivative.

  Any of the dibenzothienyl groups in the general formula (1) may be substituted with an amino group at the 3-position.

  According to this viewpoint, the light emission lifetime of the organic EL element can be further improved by using such a monoamine derivative.

R ₁ and R ₂ may be independently a hydrogen atom or a phenyl group.

  According to this viewpoint, the light emission lifetime of the organic EL element can be further improved by using such a monoamine derivative.

  In order to solve the above-mentioned problem, according to another aspect of the present invention, an organic electrolysis device comprising the monoamine derivative described above in at least one or more layers disposed between an anode and a light-emitting layer. A luminescence element is provided.

  According to this viewpoint, it is possible to provide an organic EL element having an improved emission lifetime.

  As described above, according to the present invention, the light emission lifetime of the organic EL element can be improved.

It is a schematic diagram which shows an example of the organic EL 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. Monoamine Derivative According to One Embodiment of the Present Invention>
First, a monoamine derivative according to an embodiment of the present invention will be described. The monoamine derivative according to the present embodiment is a compound represented by the following general formula (1) that can be suitably used as a hole transport material of an organic EL element.

上記一般式（１）において、
Ｒ_１およびＲ_２は、互いに独立して、水素原子、ハロゲン（ｈａｌｏｇｅｎ）原子、置換もしくは無置換の炭素数１以上１５以下のアルキル（ａｌｋｙｌ）基、置換もしくは無置換の環形成炭素数６以上３０以下のアリール（ａｒｙｌ）基、または置換もしくは無置換の環形成炭素数１以上３０以下のヘテロアリール（ｈｅｔｅｒｏａｒｙｌ）基であり、
ａおよびｂは、互いに独立して、１以上４以下の整数であり、
Ａｒ_１は、以下の一般式（２）で表される置換基である。

In the general formula (1),
R ₁ and R ₂ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, a substituted or unsubstituted ring carbon number of 6 or more. An aryl group having 30 or less, or a heteroaryl group having 1 to 30 ring carbon atoms of a substituted or unsubstituted ring,
a and b are each independently an integer of 1 or more and 4 or less,
Ar ₁ is a substituent represented by the following general formula (2).

In the above general formula (2),
Ar _{2 to} Ar ₄ are each independently an unsubstituted aryl group having 6 to 50 ring carbon atoms,
l and m are integers such that l + m is 0 or more and 2 or less.

In the above general formula (1), the substituent substituted for R ₁ and R ₂ does not include an amino group in the structure. That is, the compound represented by the general formula (1) is a monoamine derivative having only one amino group in the structural formula.

Here, in the general formula (2), Ar _{2 to} Ar ₄ are each independently an unsubstituted aryl group. As demonstrated in the Example mentioned later, when Ar < ₂ > -Ar < ₄ > is unsubstituted, the monoamine derivative represented by General formula (1) can improve the light emission lifetime of an organic EL element.

Specifically, when Ar _{2 to} Ar ₄ have no substituent and Ar ₁ has a structure in which only Ar _{2 to} Ar ₄ are connected in series, as demonstrated in the examples described later. The monoamine derivative represented by the general formula (1) can improve the emission lifetime of the organic EL device. On the other hand, when Ar _{2 to} Ar ₄ have a substituent and Ar ₁ has a structure branched by a substituent other than Ar _{2 to} Ar ₄ , the general formula ( The monoamine derivative represented by 1) cannot improve the light emission lifetime of the organic EL device.

In the general formula (2), Ar _{2 to} Ar ₄ are preferably each independently an aryl group having 6 to 14 ring carbon atoms, which is unsubstituted. Specifically, Ar _{2 to} Ar ₄ are each independently a phenyl group, a naphthyl group, an anthracenyl group, a fluorenyl group, a phenanthryl group, a biphenyl group. ) Group or the like. On the other hand, a substituent having a ring-forming carbon number exceeding 14 (for example, a pyrenyl group (ring-forming carbon number 18) or the like) increases the electron transport property of the monoamine derivative, thereby causing the organic layer on the anode side from the light emitting layer. Increase electron diffusion. This is not preferable because the electron resistance of the hole transport layer or the hole injection layer is lowered and the light emission lifetime of the organic EL element is lowered.

Moreover, in the said General formula (2), it is preferable that the sum total of the aromatic ring which Ar < ₂ > -Ar < ₄ > has is 1 or more and 3 or less.

_Here, the sum of the aromatic rings Ar 2 to Ar ₄ has _a value obtained by adding each number of benzene (benzene) rings Ar 2 to Ar ₄ has.

For example, when l = m = 0 and Ar ₄ is a phenanthryl group (that is, when Ar ₁ is a phenanthryl group), since the phenanthryl group is a condensed ring group in which three benzene rings are condensed, Ar ₂ to The sum of the aromatic rings of Ar ₄ is “3”. Further, when l = m = 1 and Ar ₂ , Ar ₃ and Ar ₄ are phenyl groups (that is, when Ar ₁ is a terphenyl group), the phenyl group is a benzene ring monocyclic substituent. , Ar _{2 to} Ar ₄ have a total sum of aromatic rings “3” due to “1 + 1 + 1”. In addition, when l = 0, m = 1, and Ar ₃ is a phenyl group and Ar ₄ is a naphthyl group (that is, when Ar ₁ is a naphthylphenyl group), the phenyl group is a benzene ring monocyclic substituent. Yes, since the naphthyl group is a condensed ring group obtained by condensing two benzene rings, the sum of the aromatic rings of Ar _{2 to} Ar ₄ is “3” due to “1 + 2”.

Furthermore, as another example, when l = m = 0 and Ar ₄ is a fluorenyl group, l = m = 0 and Ar ₄ is a naphthyl group, or l = 0, m = 1, and When Ar ₃ and Ar ₄ are phenyl groups, the sum of the aromatic rings of Ar _{2 to} Ar ₄ is “2”.

When Ar _{2 to} Ar ₄ are substituents such that the sum of the aromatic rings is 1 or more and 3 or less as described above, it is represented by the general formula (1) as demonstrated in the examples described later. The monoamine derivative can further improve the light emission lifetime of the organic EL device.

  In the general formula (1), at least one dibenzothienyl group is substituted with an amino group at the 3-position in the dibenzothiophene ring. Accordingly, in the monoamine derivative represented by the general formula (1), the dibenzothienyl group is stabilized, and thus the chemical stability is improved. Therefore, in the organic EL element using the monoamine derivative represented by the general formula (1) having high chemical stability, the emission lifetime is improved.

  This is because the lone electron pair of the nitrogen atom of the amino group affects the sulfur atom of the dibenzothienyl group due to the electron donating property and destabilizes the heterocycle containing the sulfur atom. Specifically, when the nitrogen atom of the amino group and the sulfur atom of the dibenzothienyl group are present in the positional relationship of the para position of the benzene ring (when the amino group is substituted at the 2-position of the dibenzothiephen ring) ), The influence of destabilization from the lone electron pair of the nitrogen atom of the amino group to the sulfur atom of the dibenzothienyl group is increased.

  For this reason, at least one of the dibenzothienyl groups is preferably substituted with the amino group at the substitution position having the least influence from the lone electron pair of the nitrogen atom of the amino group. Specifically, in the dibenzothiophene ring, Substitution with an amino group at the 3-position is preferred.

  In order to minimize the influence of the lone electron pair of the nitrogen atom of the amino group on the heterocycle containing the sulfur atom, in the general formula (1), all of the dibenzothienyl groups are 3 in the dibenzothiophene ring. More preferably, the amino group is substituted at the position. In such a case, the chemical stability of the monoamine derivative represented by the general formula (1) is further improved. Therefore, in the organic EL element using such a monoamine derivative, the emission lifetime is further improved.

In the above general formula (1), R ₁ and R ₂ may be any substituent. For example, R ₁ and R ₂ may be each independently a hydrogen atom or a phenyl group.

  In the organic EL device, the monoamine derivative represented by the general formula (1) is preferably contained in at least one or more layers disposed between the light emitting layer and the anode of the organic EL device. Specifically, the monoamine derivative represented by the general formula (1) is preferably contained in the hole transport layer or the hole injection layer of the organic EL element.

  However, in the organic EL element, the layer containing the monoamine derivative represented by the general formula (1) is not limited to the above examples. For example, the monoamine derivative represented by the general formula (1) may be contained in any of the organic layers sandwiched between the anode and the cathode of the organic EL element.

  In particular, the monoamine derivative represented by the general formula (1) can be suitably used for a hole transport layer of an organic EL element having a light emitting layer containing a blue light emitting material or a green light emitting material. When the monoamine derivative represented by the general formula (1) is used in the hole transport layer of such an organic EL element, the light emission lifetime of the organic EL element can be further improved.

  In addition, as a representative example of the aryl group in the above general formulas (1) and (2), a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, an anthryl group ) Group, phenanthrenyl group, fluorenyl group, indenyl group, pyrenyl group, fluoranthenyl group, triphenylenyl group, and the like.

  In addition, as typical examples of the heteroaryl group in the above general formula (1), a pyrazinyl group, a pyrrolyl group, a pyridyl group, a pyrimidyl group, a pyridazyl group, and a pyrazyl group (Pyrazinyl) group, furanyl group, pyranyl group, thienyl group, quinolyl group, isoquinolyl group, benzofuranyl group, benzothienyl group indolyl group, benzoxazolyl group, benzothiazolyl group, quinoki A quinoxalyl group, a benzimidazolyl group, a pyrazolyl group, a tetrazolyl group, an imidazolyl group, an oxazolyl group, an oxazolyl group, an azolyl group An isothiozyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothienyl group, and the like can be given.

  In addition, as representative examples of the alkyl group in the general formula (1), a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, a decyl group decyl) group, linear alkyl group such as pentadecyl group, and branched alkyl group such as t-butyl group.

  Here, the structural formula of a compound which is a specific example of the monoamine derivative represented by the general formula (1) described above is shown below. However, the monoamine derivative according to the present embodiment is not limited to the following compounds.

  As described above, the monoamine derivative represented by the general formula (1) can be suitably used as a hole transport material. Moreover, the organic EL element using the monoamine derivative represented by the general formula (1) can improve the light emission lifetime.

  The monoamine derivative according to this embodiment has been described in detail above.

<2. Organic EL Device According to One Embodiment of the Present Invention>
Next, an organic EL element using the monoamine derivative according to this embodiment will be described in detail with reference to FIG. FIG. 1 is a schematic diagram showing a configuration example of an organic EL element according to this embodiment.

  As shown in FIG. 1, the organic EL device 100 according to this embodiment includes a substrate 110, a first electrode 120 disposed on the substrate 110, a hole injection layer 130 disposed on the first electrode 120, and , A hole transport layer 140 disposed on the hole injection layer 130, a light emitting layer 150 disposed on the hole transport layer 140, an electron transport layer 160 disposed on the light emitting layer 150, and an electron transport layer The electron injection layer 170 disposed on the electrode 160 and the second electrode 180 disposed on the electron injection layer 170 are provided.

  For example, the monoamine derivative according to the present embodiment may be included in at least one of the hole injection layer 130 and the hole transport layer 140 disposed between the first electrode 120 and the light emitting layer 150. preferable.

  As the substrate 110, a substrate used in a general organic EL element can be used. For example, the substrate 110 may be a glass substrate, a semiconductor substrate, a transparent plastic substrate, or the like.

A first electrode 120 is formed on the substrate 110. The first electrode 120 is, for example, an anode, and is formed as a transmission electrode using a metal, an alloy, a conductive compound, or the like having a high work function. Specifically, the first electrode 120 is transparent and has excellent conductivity, indium tin oxide (In ₂ O ₃ —SnO ₂ : ITO), indium zinc oxide (In ₂ O ₃ —ZnO), tin oxide (SnO). ₂ ), zinc oxide (ZnO), or the like. The first electrode 120 may be formed as a reflective electrode in which magnesium (Mg), aluminum (Al), or the like is laminated on the transparent conductive film.

  A hole injection layer 130 is formed on the first electrode 120. The hole injection layer 130 is a layer having a function of facilitating injection of holes from the first electrode 120, and is formed with a thickness of about 10 nm to about 150 nm, for example.

  The hole injection layer 130 may be formed of a monoamine derivative represented by the general formula (1), or may be formed of a known hole injection material. Known hole injection materials for forming the hole injection layer 130 include, for example, 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, Ndiphenylamino} triphenylamine (TDATA), 4,4 , 4 "-tris (N, N-2-naphthylphenylamino) triphenylamine (2-TNATA), polyaniline / dodecylbenzenesulfonic acid (Pani / DBSA), poly (3,4-ethylenedioxythiophene) / poly (4-styrene sulfonate) (PEDOT / PSS), polyaniline / camphor sulfonic acid (Pani / CSA), polyaniline / poly (4-styrene sulfonate) (PANI / PSS), and the like.

  A hole transport layer 140 is formed on the hole injection layer 130. The hole transport layer 140 is a layer having a function of transporting holes, and is formed with a thickness of about 10 nm to about 150 nm, for example. Note that the hole transport layer 140 may be formed of a plurality of layers.

  Here, the hole transport layer 140 is preferably formed of a monoamine derivative represented by the general formula (1). When the monoamine derivative represented by the general formula (1) is included in another layer (for example, the hole injection layer 130), the hole transport layer 140 is formed of a known hole transport material. Also good. Known hole transport materials include, for example, carbazole derivatives such as 1,1-bis [(di-4-tolylamino) phenyl] cyclohexane (TAPC), N-phenylcarbazole, and polyvinylcarbazole. 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.

  A light emitting layer 150 is formed on the hole transport layer 140. The light emitting layer 150 is a layer that emits light by fluorescence, phosphorescence, or the like, and is formed with a thickness of about 10 nm to about 60 nm, for example. As the light emitting material of the light emitting layer 150, a known light emitting material can be used. Specifically, known luminescent materials such as fluoranthene derivatives, styryl derivatives, pyrene derivatives, arylacetylene derivatives, fluorene derivatives, perylene derivatives, chrysene chrysene) derivatives and the like can be used. In addition, styryl derivatives, pyrene derivatives, perylene derivatives, and anthracene derivatives can be preferably used. For example, an anthracene derivative represented by the following general formula (3) may be used as the light emitting material of the light emitting layer 150.

In the general formula (3),
Ar ₆ is independently of each other a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, or a substituted or unsubstituted cycloalkyl having 3 to 50 ring carbon atoms. (Cycloalkyl) group, substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, substituted or unsubstituted aralkyl group having 7 to 50 carbon atoms, substituted or unsubstituted ring carbon number An aryloxy group having 6 to 50 carbon atoms, a substituted or unsubstituted arylthio group having 6 to 50 ring carbon atoms, and an alkoxycarbonyl group having 2 to 50 carbon atoms substituted or unsubstituted. Substituted or unsubstituted ring-forming carbon atoms of 6 to 50 Aryl group, heteroaryl group having 5 to 50 ring carbon atoms, substituted or unsubstituted silyl group, carboxyl group, halogen atom, cyano group , A nitro group or a hydroxyl group,
p is an integer of 1 or more and 10 or less.

Specifically, Ar ₆ is independently of each other a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenylnaphthyl group, a naphthylphenyl group, an anthryl group, a phenanthryl group, a fluorenyl group, an indenyl group, a pyrenyl group, Acetonaphthenyl, fluoranthenyl, triphenylenyl, pyridyl, furanyl, pyranyl, thienyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, benzoxazolyl, benzothiazolyl Quinoxalyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group and the like. Preferably, Ar ₆ may be a phenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothienyl group, or the like.

  The compound represented by the above general formula (3) is, for example, compounds a-1 to a-12 represented by the following structural formula. However, the compound represented by the general formula (3) is not limited to the following compounds a-1 to a-12.

  The light-emitting layer 150 includes, for example, 1,4-bis [2- (3-N-ethylcarbazolyl) vinyl] benzene (BCzVB), 4- (di-p-tolylamino) -4 ′-[ (Di-p-tolylamino) style] stilbene (DPAVB), N- (4-((E) -2- (6-((E) -4- (diphenylamino) styl) naphthalen-2-yl) vinyl) phenyl) ) -N-phenylbenzenamine (N-BDAVBi) or the like may be used. Further, for the light emitting layer 150, for example, 2,5,8,11-tetra-t-butylperylene (TBPe) may be used as the perylene derivative, and for example, 1,1-dipylene, 1,4-diphenylbenzene, 1,4-bis (N, N-diphenylamino) pyrene, or the like may be used. However, the present invention is not limited to the above exemplary compounds.

  An electron transport layer 160 is formed on the light emitting layer 150. The electron transport layer 160 is a layer having a function of transporting electrons, and is formed with a thickness of about 15 nm to about 50 nm, for example.

  The electron transport layer 160 may be formed of a known electron transport material. Examples of known electron transporting materials include tris (8-hydroxyquinolinato) aluminum (Alq3) and materials having a nitrogen-containing aromatic ring. Specific examples of the material having a nitrogen-containing aromatic ring include, for example, a material containing a pyridine ring such as 1,3,5-tri [(3-pyridyl) -phen-3-yl] benzene, A material containing a triazine ring such as 4,6-tris (3 ′-(pyridin-3-yl) biphenyl-3-yl) -1,3,5-triazine, 2- (4- (N- Examples thereof include materials containing an imidazole derivative such as phenylbenzimidazolyl-1-ylphenyl) -9,10-dinephthylanthracene.

An electron injection layer 170 is formed on the electron transport layer 160. The electron injection layer 170 is a layer having a function of facilitating injection of electrons from the second electrode 180, and is formed with a thickness of about 0.3 nm to about 9 nm. As the electron injection layer 170, any material known as a material for forming the electron injection layer 170 can be used. For example, the electron injection layer 170 is formed of a lithium complex such as lithium 8-quinolinate (Liq) or lithium fluoride (LiF), sodium chloride (NaCl), cesium fluoride (CsF), lithium oxide (Li ₂ O), or barium oxide. It may be formed using (BaO) or the like.

  A second electrode 180 is formed on the electron injection layer 170. The second electrode 180 is, for example, a cathode, and 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 180 is, for example, a metal such as lithium (Li), magnesium (Mg), aluminum (Al), or calcium (Ca), aluminum-lithium (Al-Li), magnesium-indium (Mg-In), magnesium. -It may be formed of a mixture of metals such as silver (Mg-Ag). In addition, the second electrode 180 may be formed as a transmissive electrode using a thin film of 20 nm or less of the above metal material or a transparent conductive film such as indium tin oxide or indium zinc oxide.

  Note that each of the above-described layers can be formed by selecting a known appropriate film forming method corresponding to the material such as a vacuum deposition method, a sputtering method, and various coating methods. Each organic layer disposed between the first electrode 120 and the second electrode 180 can be formed by, for example, a vacuum deposition method, various coating methods, or the like. Moreover, each metal layer, such as the 1st electrode 120 and the 2nd electrode 180, can be formed by a vacuum evaporation method, a sputtering method, etc., for example.

  Heretofore, an example of the organic EL element 100 according to the present embodiment has been described. The organic EL element 100 according to the present embodiment can improve the light emission lifetime by including the monoamine derivative represented by the general formula (1).

  In addition, the structure of the organic EL element 100 which concerns on this embodiment is not limited to the said illustration. The organic EL element 100 according to the present embodiment may be formed with another known configuration. For example, the organic EL element 100 may not include one or more of the hole injection layer 130, the hole transport layer 140, the electron transport layer 160, and the electron injection layer 170, and may include other layers. Also good. Furthermore, each layer of the organic EL element 100 may be formed of a single layer or a plurality of layers.

  The organic EL element 100 includes a hole blocking layer between the hole transport layer 140 and the light emitting layer 150 in order to prevent triplet excitons or holes from diffusing into the electron transport layer 160. May be. Note that the hole blocking layer is formed of, for example, an oxadiazole derivative, a triazole derivative, or a phenanthroline derivative.

<3. Example>
Hereinafter, the monoamine derivative according to the present embodiment and the organic EL element including the monoamine derivative will be specifically described with reference to Examples and Comparative Examples. In addition, the Example shown below is an example to the last, and the monoamine derivative and organic EL element which concern on this embodiment are not limited to the following example.

[Synthesis of monoamine derivatives]
First, a method for synthesizing a monoamine derivative according to the present embodiment will be specifically described by exemplifying methods for synthesizing compounds C, E, H, and I. The synthesis method described below is merely an example, and the synthesis method of the monoamine derivative according to the present embodiment is not limited to the following example.

(Synthesis of Compound C)
Compound C, which is a monoamine derivative according to this embodiment, was synthesized according to the following reaction formula 1.

First, in an argon (Ar) atmosphere, a 500 mL three-necked flask (flask) was charged with compound A (15.00 g), cuprous oxide (0.85 g), aqueous ammonia (NH ₃ aq) (20 ml), N-methylpyrrolidone (NMP) (70 ml) was added and heated at 110 ° C. for 25 hours. After air cooling, water was added to separate the organic layer, and the solvent was distilled off from the separated organic layer. The obtained crude product was purified by silica gel column chromatography (developing solvent: hexane / ethyl acetate) to obtain Compound B as a white solid (7.4 g). , 66% yield).

  In addition, when the molecular weight measurement was performed with respect to the obtained compound B by FAB-MS (Fast Atom Bombardment-Mass Spectrometry), C14H11N and the measured value 193 were obtained.

  Subsequently, in an argon atmosphere, a 500 mL three-necked flask was charged with compound B (1.00 g), 3-bromobenzothiophene (2.99 g), bis (dibenzylideneacetone) palladium ( 0) (bis (dibenzylideneacetone)) palladium (0) (0.27 g), tri-tert-butylphosphine (0.088 g), sodium tert-butoxide (3.98 g) The mixture was heated to reflux for 7 hours in 200 mL of a toluene solvent, cooled with air, and the organic layer was separated by adding water, and the solvent was distilled off from the separated organic layer. Silica gel column chromatography Preparative chromatography: Purification (developing solvent: toluene / hexane (toluene / Hexane)), to give compound C as a white solid (1.90 g, 66% yield).

  In addition, when the molecular weight measurement by FAB-MS was performed with respect to the obtained compound C, C38H23NS2 and the measured value 557 were obtained. Moreover, it was 151 degreeC when the glass transition point Tg of the compound C was measured using the differential scanning calorimeter DSC7020 (made by Hitachi High-Tech).

(Synthesis of Compound E)
Compound E, which is a monoamine derivative according to this embodiment, was synthesized according to the following reaction formula 2.

  First, in an argon atmosphere, a 500 mL three-necked flask was charged with compound B (1.00 g), 3-bromobenzothiophene (1.50 g), bis (dibenzylideneacetone) palladium (0) (0.27 g), Tri-tert-butylphosphine (0.088 g) and sodium tert-butoxide (3.98 g) were added, and the mixture was heated to reflux in 200 mL of a toluene solvent for 7 hours. After air cooling, water was added to separate the organic layer, and the solvent was distilled off from the separated organic layer. The resulting crude product was purified by silica gel column chromatography (toluene / hexane) to obtain white solid compound D (1.15 g, yield 59%).

  In addition, when the molecular weight measurement by FAB-MS was performed with respect to the obtained compound D, C26H17NS and the measured value 375 were obtained.

  Subsequently, in an argon atmosphere, a 500 mL three-necked flask was charged with compound D (1.04 g), 3-bromobenzothiophene (0.85 g), bis (dibenzylideneacetone) palladium (0) (0.13 g). , Tri-tert-butylphosphine (0.044 g) and sodium tert-butoxide (1.99 g) were added, and the mixture was heated to reflux in 200 mL of toluene solvent for 7 hours. After air cooling, water was added to separate the organic layer, and the solvent was distilled off from the separated organic layer. The obtained crude product was purified by silica gel column chromatography (toluene / hexane) to obtain Compound E as a white solid (1.17 g, yield 76%).

  In addition, when the molecular weight measurement by FAB-MS was performed with respect to the obtained compound E, C38H23NS2 and the measured value 557 were obtained. Moreover, it was 145 degreeC when the glass transition point Tg of the compound E was measured using the differential scanning calorimeter DSC7020 (made by Hitachi High-Tech).

(Synthesis of Compound H)
Compound H, which is a monoamine derivative according to this embodiment, was synthesized according to the following reaction formula 3.

  First, in an argon atmosphere, a 500 mL three-necked flask was charged with compound F (1.00 g), 3-bromobenzothiophene (1.45 g), bis (dibenzylideneacetone) palladium (0) (0.26 g), Tri-tert-butylphosphine (0.081 g) and sodium tert-butoxide (1.96 g) were added, and the mixture was heated to reflux in 200 mL of toluene solvent for 7 hours. After air cooling, water was added to separate the organic layer, and the solvent was distilled off from the separated organic layer. The obtained crude product was purified by silica gel column chromatography (toluene / hexane) to obtain a white solid compound G (1.11 g, yield 58%).

  In addition, when the molecular weight measurement by FAB-MS was performed with respect to the obtained compound G, C24H15NS2 and the measured value 381 were obtained.

  Subsequently, under an argon atmosphere, a 500 mL three-necked flask was charged with compound G (1.00 g), 1- (4-bromophenyl) naphthalene (0.82 g), bis. (Dibenzylideneacetone) palladium (0) (0.14 g), tri-tert-butylphosphine (0.042 g) and sodium tert-butoxide (1.01 g) were added, and the mixture was heated to reflux in 200 mL of toluene solvent for 7 hours. did. After air cooling, water was added to separate the organic layer, and the solvent was distilled off from the separated organic layer. The resulting crude product was purified by silica gel column chromatography (toluene / hexane) to obtain white solid compound H (1.13 g, yield 74%).

  In addition, when the molecular weight measurement by FAB-MS was performed with respect to the obtained compound H, C40H25NS2 and the measured value 583 were obtained. Moreover, it was 130 degreeC when the glass transition point Tg of the compound H was measured using the differential scanning calorimeter DSC7020 (made by Hitachi High-Tech).

(Synthesis of Compound I)
Compound I, which is a monoamine derivative according to this embodiment, was synthesized according to the following reaction formula 4.

  Under a argon atmosphere, in a 500 mL three-necked flask, compound G (1.00 g), 4-bromo-1,1 ′: 4 ′, 1 ″ -terphenyl (4-bromo-1,1 ′: 4) was added. ', 1 ″ -terphenyl) (0.89 g), bis (dibenzylideneacetone) palladium (0) (0.14 g), tri-tert-butylphosphine (0.042 g), sodium tert-butoxide (1.01 g) ) And heated to reflux in 200 mL of toluene solvent for 7 hours. After air cooling, water was added to separate the organic layer, and the solvent was distilled off from the separated organic layer. The resulting crude product was purified by silica gel column chromatography (toluene / hexane) to obtain Compound I as a white solid (1.23 g, yield 77%).

  In addition, when the molecular weight measurement by FAB-MS was performed with respect to the obtained compound I, C42H27NS2 and the measured value 609 were obtained. Moreover, it was 130 degreeC when the glass transition point Tg of the compound I was measured using the differential scanning calorimeter DSC7020 (made by Hitachi High-Tech).

[Production of organic EL element]
Next, a blue light-emitting organic EL device including the monoamine derivative according to the present embodiment was manufactured using the vacuum deposition method according to the following procedure.

Example 1
First, after patterning in advance, a surface treatment with ultraviolet / ozone (O ₃ ) was performed on the ITO-glass substrate that had been subjected to the cleaning treatment. The film thickness of the ITO film (first electrode) on the ITO-glass substrate was 150 nm. The surface-treated substrate is put into an organic layer deposition evaporator, and a hole injection layer, a hole transport layer (HTL), a light emitting layer, and an electron transport at a degree of vacuum of 10 ⁻⁴ to 10 ⁻⁵ Pa. Layers were sequentially deposited.

  The hole injection layer was formed of 4,4 ′, 4 ″ -tris (N, N-2-naphthylphenylamino) triphenylamine (2-TNATA) with a film thickness of 60 nm. The hole transport layer (HTL) was formed with a film thickness of 30 nm from the compound C synthesized above. The light-emitting layer uses 9,10-di (2-naphthyl) anthracene (ADN) as the host material of the light-emitting material and 2,5,8,11-tetra-t as the dopant material. -It formed with the film thickness of 25 nm using the butyl perylene (TBP). The doping amount of the dopant material was 3% by mass with respect to the total mass of the host material. Further, the electron transport layer was formed of Alq3 with a film thickness of 25 nm.

Subsequently, the substrate was transferred to a metal film-forming vapor deposition machine, and the electron injection layer and the second electrode were vapor-deposited at a vacuum degree of 10 ⁻⁴ to 10 ⁻⁵ Pa to produce an organic EL element. Note that the electron injection layer was formed of LiF with a thickness of 1 nm, and the second electrode was formed of aluminum (Al) with a thickness of 100 nm.

(Example 2)
An organic EL device was produced in the same manner as in Example 1 except that the hole transport layer (HTL) was formed of Compound E.

(Example 3)
An organic EL device was produced in the same manner as in Example 1 except that the hole transport layer (HTL) was formed of Compound H.

Example 4
An organic EL device was produced in the same manner as in Example 1 except that the hole transport layer (HTL) was formed of Compound I.

(Comparative Example 1)
An organic EL device was produced in the same manner as in Example 1 except that the hole transport layer (HTL) was formed of the following compound c1. Compound c1 is a compound having a structure in which three dibenzothienyl groups are bonded to an amino group at the 3-position of the dibenzothiophene ring.

(Comparative Example 2)
An organic EL device was produced in the same manner as in Example 1 except that the hole transport layer (HTL) was formed of the following compound c2. The compound c2 is a compound in which Ar ₃ has a substituent, unlike the monoamine derivative according to this embodiment.

(Comparative Example 3)
An organic EL device was produced in the same manner as in Example 1 except that the hole transport layer (HTL) was formed of the following compound c3. Compound c3 is a compound having a structure in which three dibenzothienyl groups are bonded to an amino group at the 2-position of the dibenzothiophene ring.

[Evaluation results]
The evaluation results of the produced organic EL elements according to Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1 below. Note that a C9920-11 luminance orientation characteristic measuring apparatus manufactured by Hamamatsu Photonics was used for evaluating the light emission characteristics of the produced organic EL element. The results shown in Table 1 below were measured at a current density of 10 mA / cm ² . The light emission lifetime is the time (LT50) until the luminance of 1000 cd / m ² is halved.

  Referring to the results in Table 1, Examples 1-4 in which the hole transport layer (HTL) is formed with the monoamine derivative according to the present embodiment have the same or lower drive voltage than Comparative Examples 1-3, It can also be seen that the light emission life is improved.

Specifically, in Examples 1 to 4, it can be seen that the emission lifetime is improved compared to Comparative Examples 1 and 3 using the compound c1 or c3 in which the amino group is substituted with three dibenzothienyl groups. Further, Examples 1-4, compared to Comparative Example 2 in which Ar ₃ is used a compound c2 having a substituent, it can be seen that the emission life is improved.

  In Examples 1 to 3 using compounds C, H, and I in which two dibenzothienyl groups were substituted with amino groups at the 3-position, only one dibenzothienyl group was substituted with amino groups at the 3-position. The emission lifetime was improved as compared with Example 2 using Compound E. This indicates that any dibenzothienyl group substituted with an amino group is preferably substituted with an amino group at the 3-position of the dibenzothiophene ring.

  As can be seen from the above results, the monoamine derivative according to this embodiment has the structure represented by the general formula (1) described above, thereby improving the light emission lifetime of the organic EL device containing the monoamine derivative. it can. Therefore, the monoamine derivative according to the present embodiment can be suitably used as a material for an organic EL element, and can be particularly suitably used as a hole transport material.

  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 EL element 110 Substrate 120 1st electrode 130 Hole injection layer 140 Hole transport layer 150 Light emitting layer 160 Electron transport layer 170 Electron injection layer 180 Second electrode

Claims (6)

A monoamine derivative represented by the following general formula (1).

In the general formula (1),
R ₁ and R ₂ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms, Or a substituted or unsubstituted heteroaryl group having 1 to 30 ring carbon atoms,
a and b are each independently an integer of 1 or more and 4 or less,
Ar ₁ is a substituent represented by the following general formula (2),

In the above general formula (2),
Ar _{2 to} Ar ₄ are each independently an unsubstituted aryl group having 6 to 50 ring carbon atoms,
l and m are integers such that l + m is 0 or more and 2 or less. _2. The monoamine derivative according to claim 1, wherein Ar _{2 to} Ar ₄ are each independently an aryl group having 6 to 14 ring carbon atoms, which is unsubstituted. The monoamine derivative according to claim 1 or 2, wherein the sum of the aromatic rings of Ar _{2 to} Ar ₄ is 1 or more and 3 or less.   The monoamine derivative according to any one of claims 1 to 3, wherein each of the dibenzothienyl groups in the general formula (1) is substituted with an amino group at the 3-position. The monoamine derivative according to any one of claims 1 to 4, wherein R ₁ and R ₂ are each independently a hydrogen atom or a phenyl group. An organic electroluminescence device comprising the monoamine derivative according to any one of claims 1 to 5 in at least one or more layers disposed between an anode and a light emitting layer.

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