JP2015127313A - Carbazole compound and organic light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbazole compound which has charge transportability and exhibits a large energy band gap in a triplet state.SOLUTION: The carbazole compound is represented by the following chemical formula. In the formula, Ris a substituted or unsubstituted C-Calkyl group, a substituted or unsubstituted C-Calkenyl group, a substituted or unsubstituted C-Calkynyl group, or a substituted or unsubstituted C-Calkoxy group; Ris an arbitrary functional group; and A is a substituent group containing a charge-transporting group.

Description

  The present invention relates to a carbazole compound and an organic light emitting device.

  In recent years, organic light emitting diodes (OLEDs), which are self-luminous light emitting elements, have been actively developed.

  A general organic light emitting device has a structure in which, for example, an anode is formed on a substrate, and a hole transport layer, a light emitting layer, an electron transport layer, and a cathode are sequentially formed on the anode.

  In such an organic light-emitting device, when a voltage is applied between the anode and the cathode, holes injected from the anode move to the light-emitting layer through the hole transport layer, and electrons injected from the cathode become electrons. It moves to the light emitting layer via the transport layer. Then, the transferred holes and electrons are recombined in the light emitting layer, and light emission occurs as the generated excitons transition to the ground state.

  Here, in order to improve the light emission efficiency, the light emitting layer includes a host material.

  As such a host material, for example, a carbazole compound having a hole transport ability and a large energy band gap in a triplet state is used. Specifically, a carbazole compound such as 4,4′-N, N′-dicarbazole-biphenyl (CBP) or 1,3-bis (carbazol-9-yl) benzene (mCP) is a host material for an organic light-emitting element. Known as.

  Patent Document 1 discloses a compound imparted with an electron transporting ability by introducing a substituent into the N-position, 2-position, and 3-position of such a carbazole compound.

JP 2003-335753 A

  However, the carbazole compound in which a charge transporting group is introduced at any one of the N-position, the 2-position, and the 3-position disclosed in Patent Document 1 has a problem that the energy band gap in the triplet state becomes small. It was.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a novel carbazole compound having a charge transporting ability and a large energy band gap in the triplet state, and An object of the present invention is to provide an organic light emitting device containing the carbazole compound.

・・化学式１
前記化学式１において、
Ｒ_１は、ハロゲン（ｈａｌｏｇｅｎ）、ヒドロキシル（ｈｙｄｒｏｘｙｌ）基、シアノ（ｃｙａｎｏ）基、ニトロ（ｎｉｔｒｏ）基、アミノ（ａｍｉｎｏ）基、アミジノ（ａｍｉｄｉｎｏ）基、ヒドラジン（ｈｙｄｒａｚｉｎｅ）、ヒドラゾン（ｈｙｄｒａｚｏｎｅ）、カルボン酸（ｃａｒｂｏｘｙｌｉｃ ａｃｉｄ）基やその塩、スルホン酸基（ｓｕｌｆｏｎｉｃ ａｃｉｄ）やその塩、リン酸（ｐｈｏｓｐｈｏｒｉｃ ａｃｉｄ）基やその塩、置換もしくは非置換のＣ_１−Ｃ_２０アルキル（ａｌｋｙｌ）基、置換もしくは非置換のＣ_２−Ｃ_２０アルケニル（ａｌｋｅｎｙｌ）基、置換もしくは非置換のＣ_２−Ｃ_２０アルキニル（ａｌｋｙｎｙｌ）基、置換もしくは非置換のＣ_１−Ｃ_２０アルコキシ（ａｌｋｏｘｙ）基であり、
Ｒ_２は、水素、重水素、ハロゲン、ヒドロキシル基、シアノ基、ニトロ基、アミノ基、アミジノ基、ヒドラジン、ヒドラゾン、カルボン酸基やその塩、スルホン酸基やその塩、リン酸基やその塩、置換もしくは非置換のＣ_１−Ｃ_２０アルキル基、置換もしくは非置換のＣ_２−Ｃ_２０アルケニル基、置換もしくは非置換のＣ_２−Ｃ_２０アルキニル基、置換もしくは非置換のＣ_１−Ｃ_２０アルコキシ基、置換もしくは非置換のＣ_６−Ｃ_６０アリール（ａｒｙｌ）基、置換もしくは非置換のＣ_６−Ｃ_６０アリールオキシ（ａｒｙｌｏｘｙ）基、置換もしくは非置換のＣ_６−Ｃ_６０アリールチオ（ａｒｙｌｔｈｉｏ）基、または置換もしくは非置換のＣ_２−Ｃ_６０ヘテロアリール（ｈｅｔｅｒｏａｒｙｌ）基であり、
Ａは、電荷輸送性基を含む置換基群である。 In order to solve the above problems, according to one aspect of the present invention, a carbazole compound represented by the following chemical formula 1 is provided.

..Chemical formula 1
In Formula 1,
R ₁ represents a halogen, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine, a hydrazone, a carvone. A carboxylic acid group or salt thereof, a sulfonic acid group or salt thereof, a phosphoric acid group or salt thereof, a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, substituted or unsubstituted _C 2 _{-C 20} alkenyl (alkenyl) group, a substituted or unsubstituted _C 2 _{-C 20} alkynyl (alkynyl) groups, substituted or unsubstituted _C 1 _{-C 20} alkoxy (alkoxy) group,
R ₂ is hydrogen, deuterium, halogen, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine, hydrazone, carboxylic acid group or salt thereof, sulfonic acid group or salt thereof, phosphoric acid group or salt thereof , substituted or unsubstituted _C 1 _{-C 20} alkyl group, a substituted or unsubstituted _C 2 _{-C 20} alkenyl group, a substituted or unsubstituted _C 2 _{-C 20} alkynyl group, a substituted or unsubstituted _C 1 _{-C 20} alkoxy group, a substituted or unsubstituted _C 6 _{-C 60} aryl (aryl) groups, substituted or unsubstituted _C 6 _{-C 60} aryloxy (aryloxy) group, a substituted or unsubstituted _C 6 _{-C 60} arylthio (arylthio) a group or a substituted or unsubstituted _C 2 _{-C 60} heteroaryl (heteroaryl) group,
A is a substituent group including a charge transporting group.

  According to this aspect, the carbazole compound according to one embodiment of the present invention has a charge transport capability and can increase the energy band gap in the triplet state.

A is represented by-(Ar) _n -E,
n is an integer from 0 to 5, n groups of Ar independently of one another, substituted or unsubstituted _C 6 _{-C 60} arylene group or a substituted or unsubstituted _C 2 _{-C 60} heteroarylene group, Yes, E may be a charge transporting group.

  According to this aspect, the carbazole compound according to an embodiment of the present invention can have a good charge transport capability.

The n Ar may be each independently a substituted or unsubstituted C ₆ -C ₆₀ arylene group.

  According to this aspect, the carbazole compound according to an embodiment of the present invention can have a good charge transport capability.

  The n is 1 or 2, and the n Ars may be a substituted or unsubstituted phenylene group independently of each other.

  According to this aspect, the carbazole compound according to an embodiment of the present invention can have a good charge transport capability.

  E is a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidyl group, a substituted or unsubstituted dibenzofuran group, or a substituted or unsubstituted triazyl group. May be.

  According to this aspect, the carbazole compound according to an embodiment of the present invention can have a good charge transport capability.

R ₁ may be a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, or a substituted or unsubstituted C ₁ -C ₂₀ alkoxy group.

  According to this aspect, the carbazole compound according to one embodiment of the present invention can increase the energy band gap in the triplet state.

R ₁ may be a substituted or unsubstituted methyl group, or a substituted or unsubstituted ethyl group.

  According to this aspect, the carbazole compound according to one embodiment of the present invention can increase the energy band gap in the triplet state.

R ₂ may be hydrogen, deuterium, a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, or a substituted or unsubstituted C ₆ -C ₆₀ aryl group.

  According to this aspect, the carbazole compound according to one embodiment of the present invention can increase the energy band gap in the triplet state.

The carbazole compound may be any one of the following compounds.

  According to this aspect, the carbazole compound according to one embodiment of the present invention has a charge transport capability and can increase the energy band gap in the triplet state.

  The carbazole compound may have at least one of fluorine and alkoxy groups as a substituent.

  According to this aspect, the carbazole compound according to one embodiment of the present invention has a charge transport capability and can increase the energy band gap in the triplet state.

  Moreover, in order to solve the said subject, according to another viewpoint of this invention, the organic light emitting element which contains said carbazole compound in a light emitting layer is provided.

  According to this viewpoint, the luminous efficiency and lifetime of the organic light emitting device can be improved.

  As described above, according to the present invention, it is possible to provide a novel carbazole compound having a charge transport ability and a large energy band gap in the triplet state, and an organic light emitting device including the carbazole compound. .

It is the schematic which shows an example of the structure of the organic light emitting 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. Carbazole compound according to one embodiment of the present invention>
First, a carbazole compound according to an embodiment of the present invention will be described.

  In general, it is known that a carbazole compound has a hole transporting ability and has a large energy band gap in a triplet state, and therefore becomes a host material for an organic light emitting device. Specifically, carbazole compounds such as 4,4′-N, N′-dicarbazole-biphenyl (CBP) and 1,3-bis (carbazol-9-yl) benzene (mCP) are known as host materials. It has been.

  However, although the above carbazole compound has a high hole transport ability, it has a low electron transport ability. Therefore, when the above carbazole compound is used as a host material, the carrier balance between holes and electrons in the organic light emitting device is not good, and sufficient light emission efficiency and lifetime cannot be realized.

  Therefore, it has been studied to introduce an electron transporting group into the carbazole compound to improve the light emission efficiency and the lifetime. For example, Patent Document 1 discloses a carbazole compound in which an electron transporting group is introduced at any one of the N-position, the 2-position, and the 3-position.

  However, the carbazole compound in which a substituent is introduced at any of the N-position, 2-position, and 3-position has a problem that the energy band gap in the triplet state becomes smaller than the carbazole compound to which no substituent is introduced. there were. In addition, since the N-position, 2-position, and 3-position of the carbazole group are more reactive than other positions, the carbazole group is selectively selected at positions other than the N-position, 2-position, and 3-position (for example, the 1-position). It was difficult to introduce a substituent.

  As a result of intensive studies on the above problems and the like, the present inventor has come up with the present invention. The present invention is a carbazole compound having a substituent group containing a charge transporting group at the 1-position of a carbazole group and represented by the following chemical formula 1.

・・・化学式１

... Chemical formula 1

In the above chemical formula 1, R ₁ is halogen, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine, hydrazone, carboxylic acid group or its salt, sulfonic acid group or its salt, phosphoric acid group or its salt, a substituted or unsubstituted _C 1 _{-C 20} alkyl group, a substituted or unsubstituted _C 2 _{-C 20} alkenyl group, a substituted or unsubstituted _C 2 _{-C 20} alkynyl groups, _C 1 -C substituted or unsubstituted ₂₀ alkoxy groups.

In the above chemical formula 1, R ₂ is hydrogen, deuterium, halogen, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine, hydrazone, carboxylic acid group or a salt thereof, sulfonic acid group or the like salt, phosphoric acid group or a salt thereof, a substituted or unsubstituted _C 1 _{-C 20} alkyl group, a substituted or unsubstituted _C 2 _{-C 20} alkenyl group, a substituted or unsubstituted _C 2 _{-C 20} alkynyl group, a substituted or unsubstituted _C 1 _{-C 20} alkoxy group, a substituted or unsubstituted _C 6 _{-C 60} aryl group, a substituted or unsubstituted _C 6 _{-C 60} aryloxy group, a substituted or unsubstituted _C 6 _{-C 60} arylthio group Or a substituted or unsubstituted C ₂ -C ₆₀ heteroaryl group.

  Further, in the above chemical formula 1, A is a substituent group including a charge transporting group.

Specifically, A may be a substituent group represented by-(Ar) _n -E. Here, n is an integer from 0 to 5, n groups of Ar independently of one another, substituted or unsubstituted _C 6 _{-C 60} arylene group or a substituted or unsubstituted _C 2 _{-C 60} heteroarylene, And E is a charge transporting group.

More specifically, n Ar may be each independently a substituted or unsubstituted C ₆ -C ₆₀ arylene group. More preferably, n is 1 or 2, and the n Ar may be each independently a substituted or unsubstituted phenylene group.

  Furthermore, E which is a charge transporting group may be a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidyl group, a substituted or unsubstituted dibenzofuran group, or a substituted or unsubstituted triazyl group.

Specifically, R ₁ may be a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, or a substituted or unsubstituted C ₁ -C ₂₀ alkoxy group. More preferably, R ₁ may be a substituted or unsubstituted methyl group, or a substituted or unsubstituted ethyl group.

Specifically, R ₂ may be hydrogen, deuterium, a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, or a substituted or unsubstituted C ₆ -C ₆₀ aryl group.

Here, examples of the carbazole compound according to one embodiment of the present invention include the compounds exemplified below, but the present invention is not limited thereto. In the following, R is a butyl group (Bu).

  Furthermore, the carbazole compound according to one embodiment of the present invention may have at least one of fluorine and alkoxy groups as a substituent. For example, in the compounds exemplified above, any hydrogen may be substituted with a fluorine or alkoxy group.

  The carbazole compound according to one embodiment of the present invention described above has a charge transporting ability by a substituent group including a charge transporting group introduced at the 1-position of the carbazole group. In the carbazole compound according to one embodiment of the present invention, the position where the substituent group containing a charge transporting group is introduced is not the N-position, the 2-position, or the 3-position of the carbazole group, The energy band gap in the triplet state can be increased.

  Moreover, the organic light emitting element containing the carbazole compound having the above hole transport ability and electron transport ability can improve the carrier balance between holes and electrons. Therefore, according to the carbazole compound according to an embodiment of the present invention, the light emission efficiency and lifetime of the organic light emitting device can be improved.

  The carbazole compound according to one embodiment of the present invention can be synthesized by using a known organic synthesis method, and a specific synthesis method can be used by those skilled in the art with reference to the examples described later. Can be easily understood.

Here, in the present specification, specific examples of the unsubstituted C ₁ -C ₆₀ alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, Cyclopropyl group, butyl group, isobutyl group, tert-butyl group, cyclobutyl group, pentyl group, isopentyl group, neopentyl group , Cyclopentyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, nonyl group, Sil (decyl) chain or cyclic alkyl group of _C 1 _{-C 60,} such as a group can be exemplified. Further, the substituted C ₁ -C ₆₀ alkyl group refers to one or more hydrogen atoms of the above-described unsubstituted C ₁ -C ₆₀ alkyl group, which are deuterium, halogen, hydroxyl group, nitro group, cyano group. , an amino group, an amidino group, hydrazine, hydrazone, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, phosphoric acid group or a salt thereof, or _C 1 _{-C 60} alkyl _group,, C 2 _{-C 60} alkenyl groups, C ₂ -C ₆₀ alkynyl _group, C 6 _{-C 60} aryl _group, which is substituted with C 2 _{-C 60} heteroaryl group, and the like.

Further, in the present specification, the unsubstituted _C 1 _{-C 60} alkoxy group, -OA (although, A is unsubstituted _C 1 _{-C 60} alkyl group as described above) with a functional group having the formula of is there. Specific examples of the C ₁ -C ₆₀ alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and the like. Moreover, at least one or more hydrogen atoms among these alkoxy groups may be substituted with the same substituent as in the case of the above-mentioned substituted C ₁ -C ₆₀ alkyl group.

Further, in the present specification, the C ₂ -C ₆₀ alkenyl group unsubstituted in the center or end C ₂ -C ₆₀ alkyl group unsubstituted at least one carbon - containing carbon double bonds Represents what is going on. Specific examples of C ₂ -C ₆₀ alkenyl group, ethenyl (ethenyl), propenyl (propenyl) group, and a butenyl (butenyl) group. In addition, at least one hydrogen atom of these unsubstituted C ₂ -C ₆₀ alkenyl groups may be substituted with the same substituent as in the case of the above-mentioned substituted C ₁ -C ₆₀ alkyl group. .

In the present specification, unsubstituted _C 2 _{-C 60} alkynyl group _(or, C 2 _{-C 60} alkynyl group) refers to the center or end _C 2 _{-C 60} alkyl group unsubstituted least a Represents those containing one or more carbon-carbon triple bonds. Examples of the C ₂ -C ₆₀ alkynyl group include an ethynyl group and a propynyl group. Moreover, at least one or more hydrogen atoms among these alkynyl groups may be substituted with the same substituents as those in the above-described substituted C ₁ -C ₆₀ alkyl group.

In the present specification, the unsubstituted C ₆ -C ₆₀ aryl group represents a monovalent group having a C ₆ -C ₆₀ carbocycle containing one or more aromatic rings. The _C 6 _{-C 60} arylene group unsubstituted represents a divalent group having a _C 6 _{-C 60} carbon ring containing one or more aromatic rings. When the aforementioned aryl group and arylene group contain two or more rings, the two or more rings may be fused to each other. In addition, at least one hydrogen atom of these aryl group and arylene group may be substituted with the same substituent as in the above-described substituted C ₁ -C ₆₀ alkyl group.

Specific examples of the substituted or unsubstituted C ₆ -C ₆₀ aryl group include a phenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an anthracenyl group, Azulenyl group, heptalenyl group, acenaphthylenyl group, phenalenyl group, fluorenyl group, phenyl group, anthraquinyl group, anthraquinol group triphenylenyl group, pyrenyl group, chryseni (Chrysenyl) group, picenyl group, perylenyl group, pentaphenyl group, pentacenyl group, tetraphenylenyl group, hexacenyl group, rubenyl group , Trinaphthylenyl group, pyranthrenyl group, and the like. A specific example of the substituted or unsubstituted C ₆ -C ₆₀ arylene group can be understood by referring to a specific example of the substituted or unsubstituted C ₆ -C ₆₀ aryl group. The illustration of is omitted.

In the present specification, the unsubstituted C ₂ -C ₆₀ heteroaryl group includes one or more hetero atoms selected from N, O, P or S, and the remaining ring atoms. Represents a monovalent group having a ring containing one or more aromatic rings in which is C. The unsubstituted C ₂ -C ₆₀ heteroarylene group includes one or more aromatics containing one or more heteroatoms selected from N, O, P or S, and the remaining ring atoms being C. A divalent group having a ring including a group ring is represented. Here, when the aforementioned heteroaryl group and heteroarylene group contain two or more rings, the two or more rings may be fused together. One or more hydrogen atoms of these heteroaryl group and heteroarylene group may be substituted with the same substituent as in the case of the aforementioned C ₁ -C ₆₀ alkyl group.

Specific examples of the unsubstituted C ₂ -C ₆₀ heteroaryl group include a pyrazolyl group, an imidazolyl group, an oxazolyl group, a thiazolyl group, a triazolyl group, and a tetrazolyl group. (Tetrazolyl) group, oxadiazolyl group, pyridinyl group, pyrimidinyl group, triazinyl group, carbazolylyl group, carbazolyl group. ) Group, isoquinolinyl group, benzimidazolyl Benzoimidazolyl) group, an imidazopyridinyl (imidazopyridinyl) group, and the like imidazopyrimidinyl (imidazopyrimidinyl) group. A specific example of an unsubstituted C ₂ -C ₆₀ heteroarylene group can be understood with reference to a specific example of a substituted or unsubstituted C ₆ -C ₆₀ heteroaryl group. The illustration of is omitted.

Furthermore, in the present specification, the substituted or unsubstituted C ₆ -C ₆₀ aryloxy group represents —OA ₂ (where A ₂ represents a substituted or unsubstituted C ₆ -C ₆₀ aryl group), the substituted or unsubstituted _C 6 _{-C 60} arylthio group, -SA ₃ (wherein, _{a 3} is, _C 6 _{-C 60} aryl groups substituted or unsubstituted) represents a.

<2. Organic Light-Emitting Element According to One Embodiment of the Present Invention>
Next, an organic light emitting device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram illustrating an example of the structure of an organic light emitting device according to an embodiment of the present invention.

  As shown in FIG. 1, the organic light emitting device 100 according to an embodiment of the present invention includes a substrate 110, a first electrode 120 disposed on the substrate 110, and a hole injection disposed on the first electrode 120. A layer 130, 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, The electron injection layer 170 arrange | positioned on the electron carrying layer 160 and the 2nd electrode 180 arrange | positioned on the electron injection layer 170 are provided.

  The carbazole compound according to an embodiment of the present invention is included in any layer between the first electrode 120 and the second electrode 180 of the organic light emitting device. Preferably, the carbazole compound according to an embodiment of the present invention is included as a host material in the light emitting layer 150.

  As the substrate 110, a substrate used in a general organic light emitting device can be used. For example, the substrate 110 may be a glass substrate, a semiconductor substrate, or a transparent plastic substrate.

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. The first electrode 120 is, for example, transparent and may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), zinc oxide (ZnO) or the like having excellent conductivity. . The first electrode 120 may be formed as a reflective electrode using magnesium (Mg), aluminum (Al), or the like.

  The hole injection layer 130 is a layer having a function of facilitating the injection of holes from the first electrode 120, and uses a vacuum deposition method, a spin coating method, an ink jet method, or the like. Formed on the first electrode 120. Further, the hole injection layer 130 may be specifically formed with a thickness of about 10 nm to about 1000 nm, more specifically about 10 nm to about 100 nm. The hole injection layer 130 can be formed using a known material. For example, N, N′-diphenyl-N, N′-bis- [4- (phenyl-m-tolyl-amino) is used. -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-styrenesulfonate) (PEDOT / PSS), polyaniline / camphorsulfonic acid (Pani / CSA), or polyaniline / poly (4-styrenesulfonate) (PANI / PSS) or the like can be used.

  The hole transport layer 140 is a layer containing a hole transport material having a function of transporting holes, and is formed on the hole injection layer 130 using a vacuum deposition method, a spin coating method, an ink jet method, or the like. In addition, the hole transport layer 140 may be specifically formed with a thickness of about 5 nm to about 200 nm, more specifically about 10 nm to about 150 nm. The hole transport layer 140 can be formed using a known hole transport material. For example, a carbazole derivative such as N-phenyl carbazole or 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).

  The light emitting layer 150 is a layer that emits light by phosphorescence, fluorescence, or the like, and is formed on the hole transport layer 140 using a vacuum deposition method, a spin coating method, an ink jet method, or the like. The light emitting layer 150 includes a host material and a dopant material, and particularly includes a carbazole compound according to an embodiment of the present invention as the host material. In addition, the light emitting layer 150 may be specifically formed with a thickness of about 10 nm to about 100 nm, more specifically about 20 nm to about 60 nm.

  In addition, the light emitting layer 150 may include other host materials, for example, tris (8-quinolinolato) aluminum (Alq3), 4,4′-N, N′-dicabazole-biphenyl (CBP), poly (n— Vinylcarbazole) (PVK), 9,10-di (naphthalen-2-yl) anthracene (ADN), 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) may also be included.

  The light emitting layer 150 may be formed as a light emitting layer that emits light of a specific color. For example, the light emitting layer 150 may be formed as a red light emitting layer, a green light emitting layer, and a blue light emitting layer. The carbazole compound according to one embodiment of the present invention can be particularly suitably used as a host material for a red light emitting layer and a green light emitting layer.

  When the light emitting layer 150 is a blue light emitting layer, a known material can be used as the blue dopant. For example, perlene and its derivatives, bis [2- (4,6-difluorophenyl) pyridinate] picoline, for example. An iridium (Ir) complex such as iridium (III) (FIrpic) can be used.

When the light emitting layer 150 is a red light emitting layer, a known material can be used as the red dopant. For example, rubrene and its derivatives, 4-dicyanomethylene-2- (p-dimethylaminostyryl) ) -6-methyl-4H-pyran (DCM) and its derivatives, iridium complexes such as bis (1-phenylisoquinoline) (acetylacetonate) iridium (III) (Ir (piq) ₂ (acac)), osmium (Os) ) Complexes, platinum complexes and the like can be used.

When the light emitting layer 150 is a green light emitting layer, a known material can be used as the green dopant. For example, coumarin and its derivatives, tris (2-phenylpyridine) iridium (III) (Ir An iridium complex such as (ppy) ₃ ) or the like can be used.

  The electron transport layer 160 is a layer containing an electron transport material having a function of transporting electrons, and is formed on the light emitting layer 150 by using a vacuum deposition method, a spin coating method, an ink jet method, or the like. In addition, the electron transport layer 160 may be specifically formed with a thickness of about 10 nm to about 100 nm, more specifically about 15 nm to about 50 nm. Note that the electron-transport layer 160 can be formed using a known electron-transport material. For example, a Li complex such as lithium quinolate (LiQ) or a quinoline such as tris (8-quinolinolato) aluminum (Alq3) ( quinoline) derivatives, 1,2,4-triazole derivatives (TAZ), bis (2-methyl-8-quinolinolato)-(p-phenylphenolate) -aluminum (BAlq), beryllium bis (benzoquinoline-10-olate) (BeBq2) or the like can be used.

The electron injection layer 170 is a layer having a function of facilitating injection of electrons from the second electrode 180, and is formed on the electron transport layer 160 using a vacuum deposition method or the like. Further, the electron injection layer 170 may be specifically formed with a thickness of about 0.1 nm to about 10 nm, more specifically about 0.3 nm to about 9 nm. Note that the electron injection layer 170 can be formed using a known material. For example, lithium fluoride (LiF), sodium chloride (NaCl), cesium fluoride (CsF), and lithium oxide (Li ₂ O) can be used. , Barium oxide (BaO) or the like can be used.

  The second electrode 180 is, for example, a cathode, and is formed on the electron injection layer 170 by vapor deposition or sputtering. Specifically, the second electrode 180 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 made of, for example, lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver ( (Mg—Ag) or the like. The second electrode 180 may be formed as a transmissive electrode using indium tin oxide (ITO), indium zinc oxide (IZO), or the like.

  The example of the structure of the organic light emitting device 100 according to one embodiment of the present invention has been described above, but the structure of the organic light emitting device 100 according to one embodiment of the present invention is not limited to the above example. The organic light emitting device 100 according to an embodiment of the present invention may be formed using other known structures of various organic light emitting devices. For example, the organic light emitting device 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. In addition, each layer of the organic light emitting device 100 may be formed of a single layer or a plurality of layers.

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

  Below, the Example which concerns on one Embodiment of this invention is described.

(Synthesis of carbazole compounds)
Compound 1 which is a carbazole compound according to one embodiment of the present invention was synthesized according to the following reaction formula.

First, in the reaction solution, compound A (500 mg, 1.29 mmol), bispinacolate diborane ((Bpin) ₂ ) (326 mg, 1.3 mmol), potassium acetate (KOAc) (252 mg, 2.6 mmol), palladium chloride Diphenylphosphinoferrocene dichloromethane complex (Pd (dppf) Cl ₂ CH ₂ Cl ₂ ) (105 mg, 0.13 mmol) was added, and the mixture was heated and stirred at 90 ° C. in 1,4-dioxane (10 mL). It was. The reaction solution was extracted with ethyl acetate (EtOAc) and purified using a column chromatogram to obtain the target compound B (486 mg).

  Compound C (100 mg, 0.55 mmol) was added to the reaction vessel, and dissolved in dimethyl sulfoxide (DMSO) (5 mL). Sodium hydride (NaH) (24 mg, 0.60 mmol) was added, and the mixture was stirred at room temperature. Ethyl bromide (EtBr) (0.05 mL, 0.66 mmol) was added, and the mixture was stirred at room temperature. Extraction was performed with chloroform, and purification was performed using a column chromatogram to obtain Compound D (80 mg).

Compound D (75 mg) was added to the reaction vessel and dissolved in an aqueous hydrochloric acid solution (5 mL). A sodium nitrite (NaNO ₂ ) aqueous solution (0.5 mol / L, 1 mL) was added dropwise at 5 ° C. or lower. Moreover, the compound E (100 mg) was obtained by making potassium iodide (KI) (100 mg, 0.60 mmol) act after 1 hour after dripping. Next, in toluene (3 mL), Compound E (85 mg), diphenyltriazine derivative (Compound B) (112 mg, 0.26 mmol), Pd (PPh ₃ ) ₄ (28 mg, 24 μmol), A tetraethylammonium hydroxide (Et ₄ NOH) aqueous solution (40 mass%, 0.40 mL, 1.2 mmol) was added, and the mixture was heated and stirred at 100 ° C. The target compound 1 (90 mg) was obtained by the above synthesis. Compound 1 was extracted with chloroform, purified using a column chromatogram, and then the structure was identified using an NMR spectrum (nuclear magnetic resonance spectrum).

(Physical property evaluation results)
Synthesized compound 1 of HOMO above (Highest Occupied Molecular Orbital), LUMO of (Lowest Unoccupied Molecular Orbital), using Gaussian 09 (Gaussian Inc.), subjected to structural optimization by the basis function B3LYP / 6-31G ^*, Physical properties were evaluated. Moreover, about triple energy level (energy level in triplet state: T1), TD-DFT calculation was further performed using basis function B3LYP / 6-31G ^** , and the physical property was evaluated.

  Further, in the same manner, a carbazole compound in which a charge transporting group is introduced at any one of the N-position, 2-position, and 3-position represented by the following structural formula (Comparative Compounds 1, 2, 3), and 4, The physical properties of HOMO, LUMO, and T1 of 4′-N, N′-dicarbazole-biphenyl (CBP) were also evaluated. Note that a charge transporting group is introduced at the N-position, the comparative compound 2 is at the 2-position, and the comparative compound 3 is at the 3-position.

  The above physical property evaluation results are shown in Table 1. In Table 1, T1 represents the energy level in the triplet state. All energy levels in Table 1 are shown as energy levels relative to vacuum levels.

  Referring to Table 1, compound 1 according to an embodiment of the present invention has HOMO and LUMO energy levels similar to those of comparative compounds 1 to 3 and CBP, and is a host of an organic light emitting device. It can be seen that it can be used as a material. Moreover, the compound 1 which concerns on one Embodiment of this invention has the high energy level (T1) in a triplet state with respect to the comparative compounds 1-3 and CBP. Therefore, according to one embodiment of the present invention, the energy band gap in the triplet state can be increased with respect to a carbazole compound in which a charge transporting group is introduced at any of the N-position, the 2-position, and the 3-position. I understand that I can do it.

  As described above, the carbazole compound according to an embodiment of the present invention has a charge transporting ability by a substituent group including a charge transporting group introduced at the 1-position of the carbazole group, and energy in a triplet state. The band gap can be increased.

  Therefore, since the organic light emitting device including the carbazole compound according to the embodiment of the present invention has a good carrier balance, the light emission efficiency and the lifetime can be improved.

  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 light emitting 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 2nd electrode

Claims (11)

A carbazole compound represented by the following chemical formula 1.

..Chemical formula 1
In Formula 1,
R ₁ is halogen, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine, hydrazone, carboxylic acid group or salt thereof, sulfonic acid group or salt thereof, phosphoric acid group or salt thereof, substituted or unsubstituted _C 1 _{-C 20} alkyl group, a substituted or unsubstituted _C 2 _{-C 20} alkenyl group, a substituted or unsubstituted _C 2 _{-C 20} alkynyl group, a substituted or unsubstituted _C 1 _{-C 20} alkoxy group,
R ₂ is hydrogen, deuterium, halogen, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine, hydrazone, carboxylic acid group or salt thereof, sulfonic acid group or salt thereof, phosphoric acid group or salt thereof , substituted or unsubstituted _C 1 _{-C 20} alkyl group, a substituted or unsubstituted _C 2 _{-C 20} alkenyl group, a substituted or unsubstituted _C 2 _{-C 20} alkynyl group, a substituted or unsubstituted _C 1 _{-C 20} alkoxy group, a substituted or unsubstituted _C 6 _{-C 60} aryl group, a substituted or unsubstituted _C 6 _{-C 60} aryloxy group, a substituted or unsubstituted _C 6 _{-C 60} arylthio group, or a substituted or unsubstituted and C, _{A 2-} C ₆₀ heteroaryl group,
A is a substituent group including a charge transporting group. A is represented by-(Ar) _n -E,
n is an integer of 0 to 5,
n groups of Ar are independently of each other, substituted or unsubstituted _C 6 _{-C 60} arylene group or a substituted or unsubstituted _C 2 _{-C 60} heteroarylene group,
The carbazole compound according to claim 1, wherein E is a charge transporting group. 3. The carbazole compound according to claim 2, wherein the n Ar are each independently a substituted or unsubstituted C ₆ -C ₆₀ arylene group. N is 1 or 2,
The carbazole compound according to claim 3, wherein the n Ar are each independently a substituted or unsubstituted phenylene group.   5. The E according to claim 2, wherein E is a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidyl group, a substituted or unsubstituted dibenzofuran group, or a substituted or unsubstituted triazyl group. The carbazole compound described. The carbazole compound according to claim 1, wherein R ₁ is a substituted or unsubstituted C ₁ -C ₂₀ alkyl group or a substituted or unsubstituted C ₁ -C ₂₀ alkoxy group. The carbazole compound according to claim 6, wherein R ₁ is a substituted or unsubstituted methyl group, or a substituted or unsubstituted ethyl group. 8. The R _{2 according to} claim 1, wherein R ₂ is hydrogen, deuterium, a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, or a substituted or unsubstituted C ₆ -C ₆₀ aryl group. The carbazole compound. The carbazole compound according to any one of claims 1 to 8, wherein the carbazole compound is any one of the following compounds.

  The carbazole compound according to claim 1, wherein the carbazole compound has at least one or more of fluorine and an alkoxy group as a substituent. The organic light emitting element which contains the carbazole compound as described in any one of Claims 1-10 in a light emitting layer.

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