JP2011231025A - Biscarbazole compound and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biscarbazole compound especially suitable for a hole transport material of an organic EL element, and an organic EL element having high luminous efficiency and excellent durability.SOLUTION: The biscarbazole compound represented by general formula (1) (wherein Ar-Arare each independently aryl which may contain a 6C-50C substituent or heteroaryl which may contain a 4C-50C substituent; Arand Ar, and Arand Areach may be mutually bonded to form a ring; Rand Rare each independently 1C-12C linear, branched or cyclic alkyl, phenyl which may contain a substituent, biphenyl or terphenyl; R-Rare each independently a hydrogen atom, halogen atom, 1C-12C linear, branched or cyclic alkyl, 1C-12C linear, branched or cyclic alkoxy, aryl which may contain a 6C-50C substituent or heteroaryl which may contain a 4C-50C substituent; with the proviso that Ar-Arare not carbazolyl and Rand Rdo not contain amino as a substituent) is used.

Description

  The present invention relates to a novel biscarbazole compound and an organic EL device using the same.

  An organic EL element is a surface-emitting element in which an organic thin film is held between a pair of electrodes, and has features such as a thin and light weight, a high viewing angle, and a high-speed response, and is expected to be applied to various display elements. . Recently, some practical applications such as mobile phone displays have begun. An organic EL element is an element that utilizes light emitted when holes injected from an anode and electrons injected from a cathode are recombined in a light emitting layer, and has a structure of a hole transport layer, a light emitting layer A multi-layer laminate type in which an electron transport layer and the like are laminated is the mainstream. Here, the charge transport layer such as the hole transport layer and the electron transport layer does not emit light by itself, but facilitates the injection of charges into the light emitting layer, and the charge injected into the light emitting layer or the light emitting layer. It plays the role of confining the energy of the generated excitons. Therefore, the charge transport layer is very important for lowering the driving voltage and improving the light emission efficiency of the organic EL element.

  As the hole transport material, an arylamine compound having an appropriate ionization potential and hole transport ability is used. For example, 4,4′-bis [N- (1-naphthyl) -N-phenyl] biphenyl (hereinafter, (Abbreviated as NPD) is well known. However, since NPD has a low glass transition temperature and easily crystallizes under high temperature conditions, there is a problem in durability of the element. In addition, the driving voltage and light emission efficiency of an element using NPD for the hole transport layer are not sufficient, and development of new materials is required.

  Against this background, recently, arylamine compounds having a carbazole ring introduced in the molecule have been reported. Since the carbazole ring has a high planarity and a rigid skeleton, the arylamine compound into which the carbazole ring is introduced can be expected to improve the glass transition temperature and the hole transport property. However, the arylamine compounds into which carbazole rings have been reported so far have a molecular structure in which nitrogen atoms are bonded to the 3rd and 6th positions of the carbazole ring (see, for example, Patent Documents 1 to 3). Since the 3-position and 6-position of the carbazole ring are para-positions of the nitrogen atom which is an electron donor property, the arylamino group substituted at the 3-position and 6-position is activated by the nitrogen atom of the carbazole ring. . That is, a compound in which an arylamino group is introduced at the 3-position and 6-position of the carbazole ring has a lower ionization potential than a normal aryl compound. Therefore, when an arylamine compound having a carbazole ring, which has been reported so far, is used for the hole transport layer, the hole injection barrier into the light emitting layer is increased, and the driving voltage of the organic EL element is increased. was there.

  Moreover, as a compound having a carbazole ring, a carbazole derivative in which the carbazole ring is made large for the purpose of improving the glass transition temperature is described (for example, see Patent Documents 4 to 6).

  Patent Document 4 discloses a structure in which a carbazole ring is dimerized or trimerized, but does not have an arylamino group in the molecule, so that hole transportability is not sufficient.

  Patent Document 5 discloses a compound in which a 9-carbazole group is substituted at the 6,6 ′ position of a 3,3′-biscarbazole skeleton. However, in the structure in which a 9-carbazole group is introduced at the 6,6′-position, the conjugation spread is not sufficient, and sufficient characteristics cannot be obtained when used as a hole transport material of an organic EL device.

  Patent Document 6 discloses a compound in which a substituent having an amino group or a condensed aromatic ring group is introduced at the 9,9′-position of a 3,3′-biscarbazole skeleton, and can be used as a light-emitting host of an organic EL device. Recommended. Since these 3,3′-biscarbazole derivatives have a sterically bulky substituent at the 9,9′-position, the molecular orbital overlap between molecules is reduced, which is a disadvantageous structure for passing holes. It has become. Therefore, the hole transport property when used as a hole transport material of an organic EL device is not sufficient.

JP 2006-151979 A JP 2006-298895 A JP 2008-044923 A Japanese Patent No. 3139321 Japanese Patent No. 3335985 JP 2008-135498 A

  An object of the present invention is to provide an 3,3′-biscarbazole compound in which an arylamino group is introduced at the 7,7′-position to improve hole transportability, and further, an organic EL having high luminous efficiency and excellent durability. An object is to provide an element.

  As a result of intensive studies, the present inventors have found that the biscarbazole compound represented by the following general formula (1) has excellent hole transport properties, and the organic EL device using the compound for the hole transport layer has a low driving voltage. The inventors have found that the luminous efficiency and durability are excellent, and have completed the present invention. That is, the present invention relates to the general formula (1)

（式中、Ａｒ^１〜Ａｒ^４は各々独立して炭素数６〜５０の置換基を有していても良いアリール基、又は炭素数４〜５０の置換基を有していても良いヘテロアリール基を表す。なお、Ａｒ^１とＡｒ^２及びＡｒ^３とＡｒ^４は互いに結合して環を形成しても良い。Ｒ^１及びＲ^２は各々独立して炭素数１〜１２の直鎖、分岐若しくは環状のアルキル基、又は置換基を有していても良いフェニル基、ビフェニル基若しくはターフェニル基を表し、Ｒ^３〜Ｒ^１４は各々独立して水素原子、ハロゲン原子、炭素数１〜１２の直鎖、分岐若しくは環状のアルキル基、炭素数１〜１２の直鎖、分岐若しくは環状のアルコキシ基、炭素数６〜５０の置換基を有していても良いアリール基、又は炭素数４〜５０の置換基を有していても良いヘテロアリール基を表す。但し、Ａｒ^１〜Ａｒ^４はカルバゾリル基を除き、Ｒ^１及びＲ^２は置換基としてアミノ基を有しない。）
で表されるビスカルバゾール化合物及びその用途に関するものである。

(In the formula, Ar ^{1 to} Ar ⁴ are each independently an aryl group optionally having a substituent having 6 to 50 carbon atoms, or a heteroaryl optionally having a substituent having 4 to 50 carbon atoms. Ar ¹ and Ar ² and Ar ³ and Ar ⁴ may be bonded to each other to form a ring, and R ¹ and R ² are each independently a straight chain or branched chain having 1 to 12 carbon atoms. Alternatively, it represents a cyclic alkyl group, or a phenyl group, biphenyl group or terphenyl group which may have a substituent, and R ^{3 to} R ¹⁴ each independently represents a hydrogen atom, a halogen atom, or a carbon number of 1 to 12. A linear, branched or cyclic alkyl group, a linear, branched or cyclic alkoxy group having 1 to 12 carbon atoms, an aryl group optionally having a substituent having 6 to 50 carbon atoms, or a carbon number of 4 to 50 A heteroaryl group optionally having a substituent Represented. ^However, Ar 1 to Ar ^4, except carbazolyl group, ^{R 1} and ^{R 2} do not have an amino group as a substituent.)
The biscarbazole compound represented by these and its use.

  Hereinafter, the present invention will be described in detail.

In the biscarbazole compound represented by the general formula (1) of the present invention, Ar ^{1 to} Ar ⁴ are each independently an aryl group optionally having a substituent having 6 to 50 carbon atoms, or 4 to 4 carbon atoms. The heteroaryl group which may have 50 substituents is represented.

Examples of the aryl group that may have a substituent having 6 to 50 carbon atoms represented by Ar ^{1 to} Ar ⁴ include a substituted or unsubstituted phenyl group, biphenylyl group, terphenyl group, naphthyl group, phenanthryl group, Anthryl group, fluorenyl group, benzofluorenyl group, dibenzofluorenyl group, fluoranthenyl group, perylenyl group, pyrenyl group, picenyl group, and chrysenyl group are preferable, specifically phenyl group, 4-methylphenyl group, 3-methylphenyl group, 2-methylphenyl group, 4-ethylphenyl group, 3-ethylphenyl group, 2-ethylphenyl group, 4-n-propylphenyl group, 4-isopropylphenyl group, 2-isopropylphenyl group, 4-n-butylphenyl group, 4-isobutylphenyl group, 4-sec-butylphenyl group, 4-te t-butylphenyl group, 4-n-pentylphenyl group, 4-isopentylphenyl group, 4-neopentylphenyl group, 4-n-hexylphenyl group, 4-n-octylphenyl group, 4-n-decylphenyl Group, 4-n-dodecylphenyl group, 4-cyclopentylphenyl group, 4-cyclohexylphenyl group, 4-tritylphenyl group, 3-tritylphenyl group, 4-triphenylsilylphenyl group, 3-triphenylsilylphenyl group, 2,4-dimethylphenyl group, 2,5-dimethylphenyl group, 3,4-dimethylphenyl group, 3,5-dimethylphenyl group, 2,6-dimethylphenyl group, 2,3,5-trimethylphenyl group, 2,3,4-trimethylphenyl group, 3,4,5-trimethylphenyl group, 4-methoxyphenyl group, 3-methyl Xyphenyl group, 2-methoxyphenyl group, 4-ethoxyphenyl group, 3-ethoxyphenyl group, 2-ethoxyphenyl group, 4-n-propoxyphenyl group, 3-n-propoxyphenyl group, 4-isopropoxyphenyl group, 2-isopropoxyphenyl group, 4-n-butoxyphenyl group, 4-isobutoxyphenyl group, 2-sec-butoxyphenyl group, 4-n-pentyloxyphenyl group, 4-isopentyloxyphenyl group, 2-iso Pentyloxyphenyl group, 4-neopentyloxyphenyl group, 2-neopentyloxyphenyl group, 4-n-hexyloxyphenyl group, 2- (2-ethylbutyl) oxyphenyl group, 4-n-octyloxyphenyl group, 4-n-decyloxyphenyl group, 4-n-dodecyloxyphenyl group, 4-n-tetradecyloxyphenyl group, 4-cyclohexyloxyphenyl group, 2-cyclohexyloxyphenyl group, 4-phenoxyphenyl group, 2-methyl-4-methoxyphenyl group, 2-methyl-5-methoxyphenyl group, 3-methyl-4-methoxyphenyl group, 3-methyl-5-methoxyphenyl group, 3-ethyl-5-methoxyphenyl group, 2-methoxy-4-methylphenyl group, 3-methoxy-4-methylphenyl group, 2,4-dimethoxyphenyl group, 2,5-dimethoxyphenyl group, 2,6-dimethoxyphenyl group, 3,4-dimethoxyphenyl group, 3,5-dimethoxyphenyl group, 3,5-diethoxyphenyl group, 3 , 5-Di-n-butoxyphenyl group, 2-methoxy-4-ethoxyphenyl group, 2-methoxy-6-ethoxy Phenyl group, 3,4,5-trimethoxyphenyl group, 4-fluorophenyl group, 3-fluorophenyl group, 2-fluorophenyl group, 2,3-difluorophenyl group, 2,4-difluorophenyl group, 2, 5-difluorophenyl group, 2,6-difluorophenyl group, 3,4-difluorophenyl group, 3,5-difluorophenyl group, 4- (1-naphthyl) phenyl group, 4- (2-naphthyl) phenyl group, 3- (1-naphthyl) phenyl group, 3- (2-naphthyl) phenyl group, 1-naphthyl group, 2-naphthyl group, 4-methyl-1-naphthyl group, 6-methyl-2-naphthyl group, 4- Phenyl-1-naphthyl group, 6-phenyl-2-naphthyl group, 2-anthryl group, 9-anthryl group, 10-phenyl-9-anthryl group, 2-fluorenyl group 9,9-dimethyl-2-fluorenyl group, 9,9-diethyl-2-fluorenyl group, 9,9-di-n-propyl-2-fluorenyl group, 9,9-di-n-octyl-2-fluorenyl Group, 9,9-diphenyl-2-fluorenyl group, 9,9′-spirobifluorenyl group, 9-phenanthryl group, 2-phenanthryl group, benzofluorenyl group, dibenzofluorenyl group, fluoranthenyl Group, pyrenyl group, chrysenyl group, perylenyl group, picenyl group, 4-biphenylyl group, 3-biphenylyl group, 2-biphenylyl group, p-terphenyl group, m-terphenyl group, o-terphenyl group, etc. However, it is not limited to these.

Moreover, as a heteroaryl group which may have a C4-C50 substituent represented by Ar < ¹ > -Ar < ⁴ >, it contains at least 1 hetero atom among an oxygen atom, a nitrogen atom, and a sulfur atom. An aromatic group, for example, 4-quinolyl group, 4-pyridyl group, 3-pyridyl group, 2-pyridyl group, 3-furyl group, 2-furyl group, 3-thienyl group, 2-thienyl group, 2- An oxazolyl group, a 2-thiazolyl group, a 2-benzoxazolyl group, a 2-benzothiazolyl group, a benzothiophenyl group, a benzoimidazolyl group, a dibenzothiophenyl group, and the like can be exemplified, but not limited thereto. .

  Furthermore, since the vapor deposition temperature at the time of organic EL element production can be lowered and the vapor deposition rate can be increased, the aryl group which may have a substituent has 6 to 30 carbon atoms. It is preferable that carbon number of the heteroaryl group which may have a substituent is 4-30.

Ar ¹ and Ar ² and Ar ³ and Ar ⁴ may be bonded to each other to form a ring. Examples of the ring formed by combining Ar ¹ and Ar ² and Ar ³ and Ar ⁴ with each other include, but are not limited to, a carbazole ring, a phenoxazine ring, a phenothiazine ring, and the like.

In the biscarbazole compound represented by the general formula (1), R ¹ and R ² may each independently have a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, or a substituent. A phenyl group, a biphenyl group or a terphenyl group is represented. However, since the molecular structure becomes bulky, R ¹ and R ² do not have an amino group as a substituent.

Specific examples of the linear, branched or cyclic alkyl group having 1 to 12 carbon atoms represented by R ¹ and R ² include methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl. Group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, trichloromethyl group, trifluoromethyl group, cyclopropyl group, cyclohexyl group, etc. can be exemplified, but not limited thereto Absent.

Moreover, as the phenyl group, biphenyl group or terphenyl group which may have a substituent represented by R ¹ and R ² , the substituted or unsubstituted phenyl group exemplified in the above Ar ^{1 to} Ar ⁴ , biphenyl Group or terphenyl group.

In the biscarbazole compound represented by the general formula (1), R ^{3 to} R ¹⁴ are each independently a hydrogen atom, a halogen atom, a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, and 1 to 1 carbon atoms. 12 linear, branched or cyclic alkoxy groups, aryl groups which may have a substituent having 6 to 50 carbon atoms, or heteroaryl groups which may have a substituent having 4 to 50 carbon atoms To express.

Examples of the halogen atom represented by R ^{3 to} R ¹⁴ include a fluorine, chlorine, bromine or iodine atom.

Examples of the linear, branched or cyclic alkyl group having 1 to 12 carbon atoms represented by R ^{3 to} R ¹⁴ include the substituents exemplified for R ¹ and R ² .

Specific examples of the linear, branched or cyclic alkoxy group having 1 to 12 carbon atoms represented by R ^{3 to} R ¹⁴ include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, Examples thereof include, but are not limited to, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, and a hexyloxy group.

Examples of the aryl group which may have a substituent having 6 to 50 carbon atoms and the heteroaryl group which may have a substituent having 4 to 50 carbon atoms represented by R ^{3 to} R ¹⁴ include the Ar Examples of the substituent include ^{1 to} Ar ⁴ .

  Preferred compounds are illustrated below, but are not limited to these compounds.

前記一般式（１）で表されるビスカルバゾール化合物は、例えば公知の方法（Ｔｅｔｒａｈｅｄｒｏｎ Ｌｅｔｔｅｒｓ，１９９８年，第３９巻，２３６７頁）によって合成することができる。具体的には、７位及び７’位がハロゲン化された３，３’−ビスカルバゾール化合物とアミン化合物とを塩基の存在下、銅触媒又はパラジウム触媒を用いて反応させ、合成することができる。

The biscarbazole compound represented by the general formula (1) can be synthesized, for example, by a known method (Tetrahedron Letters, 1998, Vol. 39, page 2367). Specifically, it can be synthesized by reacting a 3,3′-biscarbazole compound halogenated at the 7-position and 7′-position with an amine compound using a copper catalyst or a palladium catalyst in the presence of a base. .

  The biscarbazole compound represented by the general formula (1) of the present invention can be used as a light emitting layer, a hole transport layer or a hole injection layer of an organic EL device.

  In particular, since the biscarbazole compound represented by the general formula (1) is excellent in hole transport ability, when used as a hole transport layer and / or a hole injection layer, the driving voltage of the organic EL element is reduced. Thus, it is possible to achieve high luminous efficiency and improved durability.

  For the light emitting layer when the biscarbazole compound represented by the general formula (1) is used as a hole injection layer and / or a hole transport layer of an organic EL device, a conventionally known light emitting material is used. Can be used. The light emitting layer may be formed of only one kind of light emitting material, or one or more kinds of light emitting materials may be doped in the host material.

  In recent years, organic EL elements using a phosphorescent material as a light emitting material have attracted attention because of their high luminous efficiency. The biscarbazole compound represented by the general formula (1) should be used in combination with a phosphorescent material. Can do.

  When forming the hole injection layer and / or hole transport layer made of the biscarbazole compound represented by the general formula (1), two or more kinds of materials may be contained or laminated as necessary. For example, oxides such as molybdenum oxide, 7,7,8,8-tetracyanoquinodimethane, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, hexacyano A known electron accepting material such as hexaazatriphenylene may be contained or laminated.

  When the biscarbazole compound represented by the general formula (1) is used as the light emitting layer of the organic EL device, the carbazole compound is used alone, used by doping a known light emitting host material, or known fluorescence or A phosphorescent material can be doped and used.

  As a method for forming a hole injection layer, a hole transport layer, or a light emitting layer containing the biscarbazole compound represented by the general formula (1), for example, a known method such as a vacuum deposition method, a spin coating method, or a casting method is used. The method can be applied.

  The biscarbazole compound represented by the general formula (1) according to the present invention has a higher hole transporting property and a higher glass transition temperature than those of conventional materials, and therefore lowers the driving voltage, increases the luminous efficiency and durability of the organic EL element. The improvement of property can be realized.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited by these Examples.

¹ H-NMR and ¹³ C-NMR measurements were performed using Gemini 200 manufactured by Varian.

  The FDMS measurement was performed using Hitachi M-80B.

  Elemental analysis was performed by an oxygen flask combustion-IC measurement method using a fully automatic elemental analyzer (2400II) manufactured by PerkinElmer.

  The glass transition temperature was measured using DSC-3100 manufactured by Mac Science under a temperature rising condition of 10 ° C./min.

  The ionization potential was evaluated by cyclic voltammetry using HA-501 and HB-104 manufactured by Hokuto Denko.

  The current-voltage characteristic and light emission characteristic of the organic EL element were evaluated using a source meter (2400) manufactured by Keithley Instruments and a luminance meter (BM-9) manufactured by TOPCON.

Synthesis Example 1 (Synthesis of 2- (4-chlorophenyl) nitrobenzene [see the following formula (2)])
Under a nitrogen stream, in a 500 ml three-necked flask, 25.0 g (123.0 mmol) of o-bromonitrobenzene, 21.1 g (135.3 mmol) of p-chlorophenylboronic acid, 0.71 g of tetrakis (triphenylphosphine) palladium (0. 61 mmol), 100 ml of tetrahydrofuran and 162 g (307.5 mmol) of a 20 wt% aqueous potassium carbonate solution were added, and the mixture was heated to reflux for 8 hours. After cooling to room temperature, the aqueous layer and the organic layer were separated, and the organic layer was washed with a saturated aqueous ammonium chloride solution and a saturated aqueous sodium chloride solution. The extract was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (toluene), and 27.2 g of 2- (4-chlorophenyl) nitrobenzene was isolated (94% yield).

The compound was identified by ¹ H-NMR measurement and ¹³ C-NMR measurement.

¹ H-NMR (CDCl ₃ ); 7.87 (d, 1H), 7.36-7.66 (m, 5H), 7.21-7.27 (m, 2H)
¹³ C-NMR (CDCl ₃ ); 148.98, 135.85, 135.12, 134.37, 132.45, 131.79, 129.23, 128.84, 128.53, 124.21
Synthesis Example 2 (Synthesis of 2-chlorocarbazole [see the following formula (2)])
Under a nitrogen stream, a 200 ml eggplant-shaped flask was charged with 10.0 g (42.7 mmol) of 2- (4-chlorophenyl) nitrobenzene obtained in Synthesis Example 1, 50 ml of triethyl phosphite was added, and then 150 ° C. Stir for 24 hours. Triethyl phosphite was distilled off under reduced pressure, and 5.1 g (25.6 mmol) of 2-chlorocarbazole white powder was isolated by adding o-xylene to the residue and recrystallizing (yield 60%). ).

The compound was identified by ¹ H-NMR measurement and ¹³ C-NMR measurement.

¹ H-NMR (Acetone-d ₆ ); 10.46 (br-s, 1H), 8.10 (d, 2H), 7.37-7.55 (m, 3H), 7.15-7. 24 (m, 2H)
¹³ C-NMR (Acetone-d ₆ ); 141.35, 141.15, 131.33, 126.70, 123.17, 122.64, 121.92, 120.84, 120.09, 119.78 , 111.81, 111.43

合成例３ （２−クロロ−９−メチルカルバゾールの合成）
窒素気流下、２００ｍｌの三口フラスコに、合成例２で得られた２−クロロカルバゾール １０．０ｇ（４９．５ｍｍｏｌ）、ヨードメタン ８．４ｇ（５９．４ｍｍｏｌ）、ベンジルトリエチルアンモニウムクロリド １１．２ｇ（４９．５ｍｍｏｌ）、ジメチルスルホキシド １００ｍｌを加え、攪拌下、４８％水酸化ナトリウム水溶液を６．１ｇ添加した。７０℃で２時間反応後、室温まで冷却し、１００ｇの純水に反応液を加えた。析出した沈殿を濾取し、得られた白色固体を純水で洗浄した。減圧乾燥した後、エタノールで再結晶し、２−クロロ−９−メチルカルバゾールの白色粉末を６．５ｇ（３０．２ｍｍｏｌ）単離した（収率６１％）。

Synthesis Example 3 (Synthesis of 2-chloro-9-methylcarbazole)
Under a nitrogen stream, in a 200 ml three-necked flask, 10.0 g (49.5 mmol) of 2-chlorocarbazole obtained in Synthesis Example 2, 8.4 g (59.4 mmol) of iodomethane, and 11.2 g (49. 49 mmol) of benzyltriethylammonium chloride. 5 mmol), 100 ml of dimethyl sulfoxide was added, and 6.1 g of a 48% aqueous sodium hydroxide solution was added with stirring. After reacting at 70 ° C. for 2 hours, the reaction solution was cooled to room temperature, and the reaction solution was added to 100 g of pure water. The deposited precipitate was collected by filtration, and the resulting white solid was washed with pure water. After drying under reduced pressure, recrystallization with ethanol isolated 6.5 g (30.2 mmol) of 2-chloro-9-methylcarbazole white powder (yield 61%).

The compound was identified by ¹ H-NMR measurement and ¹³ C-NMR measurement.

¹ H-NMR (CDCl ₃ ); 7.99 (d, 1H), 7.90 (d, 1H), 7.12-7.49 (m, 5H), 3.70 (s, 3H)
¹³ C-NMR (CDCl ₃ ); 141.44, 141.18, 131.39, 125.93, 122.21, 121.31, 121.02, 120.22, 119.36, 119.26, 108 61, 29.17
Synthesis Example 4 (Synthesis of 7,7′-dichloro-9,9′-dimethyl-3,3′-biscarbazole)
Under a nitrogen stream, 5.7 g (26.4 mmol) of 2-chloro-9-methylcarbazole obtained in Synthesis Example 3 was dissolved in 150 ml of dichloromethane in a 300 ml three-necked flask. Thereto, 12.8 g (79.2 mmol) of iron chloride (anhydrous) was added and stirred at room temperature for 10 hours. 100 ml of methanol was added to the reaction solution, and the precipitated product was collected by filtration. The recovered crude product was washed with pure water and methanol. After purification by silica gel column chromatography (a mixed solvent of toluene and hexane), recrystallization from o-xylene further gave a yellow powder of 7,7′-dichloro-9,9′-dimethyl-3,3′-biscarbazole. 5.0 g (11.6 mmol) was isolated (yield 87%).

  The compound was identified by FDMS measurement and elemental analysis measurement.

FDMS; 428
Elemental analysis (calculated value) C = 72.7, H = 4.2, Cl = 16.5, N = 6.5
(Measured value) C = 72.5, H = 4.1, Cl = 16.6, N = 6.3
Synthesis Example 5 (Synthesis of 2-chloro-9-phenylcarbazole)
In a 300 ml three-necked flask under a nitrogen stream, 20.0 g (99.1 mmol) of 2-chlorocarbazole obtained in Synthesis Example 2, 18.5 g (119.0 mmol) of bromobenzene, 19.1 g (138.8 mmol) of potassium carbonate. ) And 100 ml of o-xylene were added, and 222 mg (0.99 mmol) of palladium acetate and 700 mg (3.4 mmol) of tri (tert-butyl) phosphine were added to the slurry-like reaction solution, followed by stirring at 130 ° C. for 24 hours. After cooling to room temperature, 80 ml of water was added and the organic layer was separated. The organic layer was washed with water and saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (a mixed solvent of toluene and hexane), and 25.6 g (92.3 mmol) of colorless oily 2-chloro-9-phenylcarbazole was isolated (yield 93%).

The compound was identified by ¹ H-NMR measurement and ¹³ C-NMR measurement.

¹ H-NMR (CDCl ₃ ); 8.08 (d, 1H), 8.01 (d, 1H), 7.16-7.64 (m, 10H)
¹³ C-NMR (CDCl ₃ ); 141.40, 141.20, 137.04, 131.66, 130.01, 127.85, 127.06, 126.19, 122.72, 121.88, 121 .11, 120.36, 120.23, 109.94, 109.87
Synthesis Example 6 (Synthesis of 7,7′-dichloro-9,9′-diphenyl-3,3′-biscarbazole)
Under a nitrogen stream, 8.0 g (28.8 mmol) of 2-chloro-9-phenylcarbazole obtained in Synthesis Example 5 was dissolved in 160 ml of dichloromethane in a 300 ml three-necked flask. Thereto, 14.0 g (86.4 mmol) of iron chloride (anhydrous) was added and stirred at room temperature for 10 hours. 100 ml of methanol was added to the reaction solution, and the precipitated product was collected by filtration. The recovered crude product was washed with pure water and methanol. After purification by silica gel column chromatography (mixed solvent of toluene and hexane), recrystallization from o-xylene further gave a brown powder of 7,7′-dichloro-9,9′-diphenyl-3,3′-biscarbazole. 7.3 g (13.2 mmol) was isolated (92% yield).

  The compound was identified by FDMS and elemental analysis.

FDMS; 552
Elemental analysis (calculated values) C = 78.1, H = 4.0, Cl = 12.8, N = 5.0
(Measured value) C = 78.1, H = 4.2, Cl = 12.7, N = 5.1
Example 1 (Synthesis of Compound (A1) and Evaluation of Thin Film Stability)
In a 50 ml three-necked flask under a nitrogen stream, 1.1 g (2.5 mmol) of 7,7′-dichloro-9,9′-dimethyl-3,3′-biscarbazole obtained in Synthesis Example 4 and diphenylamine 0. 90 g (5.3 mmol), 722 mg (7.5 mmol) of sodium-tert-butoxide, and 10 ml of o-xylene were added, and 12 mg (0.05 mmol) of palladium acetate and 37 mg of tri (tert-butyl) phosphine were added to the slurry reaction solution. 0.18 mmol) was added and stirred at 130 ° C. for 10 hours. After cooling to room temperature, 10 g of pure water was added, and the product was collected by filtration. The recovered crude product was washed with pure water and ethanol. Recrystallization from o-xylene isolated 0.6 g (0.86 mmol) of a pale yellow powder of compound (A1) (yield 33%).

  The compound was identified by FDMS measurement and elemental analysis measurement.

FDMS; 694
Elemental analysis (calculated value) C = 86.4, H = 5.5, N = 8.0
(Measured value) C = 86.4, H = 5.4, N = 8.1
The thin film formed on the glass plate by the vacuum deposition method did not show white turbidity (aggregation and crystallization) even when allowed to stand at room temperature for 1 month. The glass transition temperature was 143 ° C., which was higher than the glass transition temperature (96 ° C.) of NPD which is a conventional material.

Example 2 (Synthesis of Compound (A12) and Evaluation of Thin Film Stability)
Under a nitrogen stream, 8.0 g (14.4 mmol) of 7,7′-dichloro-9,9′-diphenyl-3,3′-biscarbazole obtained in Synthesis Example 6 and diphenylamine were placed in a 100 ml three-necked flask. 3 g (31.7 mmol), sodium tert-butoxide 3.8 g (40.4 mmol), o-xylene 50 ml were added, and palladium acetate 64 mg (0.28 mmol), tri (tert-butyl) phosphine was added to the slurry reaction solution. 204 mg (1.0 mmol) was added and stirred at 130 ° C. for 11 hours. After cooling to room temperature, 30 g of pure water was added, and the product was collected by filtration. The recovered crude product was washed with pure water and ethanol. Recrystallization from o-xylene isolated 5.8 g (7.0 mmol) of a pale yellow powder of compound (A12) (yield 48%).

  The compound was identified by FDMS measurement and elemental analysis measurement.

FDMS; 818
Elemental analysis (calculated value) C = 87.9, H = 5.1, N = 6.8
(Measured value) C = 87.8, H = 5.1, N = 6.9
When a thin film was formed on a glass plate by the same method as in Example 1, no cloudiness (aggregation and crystallization) was observed even when allowed to stand at room temperature for 1 month. The glass transition temperature was 144 ° C., which was higher than the glass transition temperature (96 ° C.) of NPD which is a conventional material.

Example 3 (Evaluation of ionization potential of compound (A1))
Compound (A1) was dissolved at a concentration of 0.001 mol / l in an anhydrous dichloromethane solution having a concentration of tetrabutylammonium perchlorate of 0.1 mol / l, and the ionization potential was measured by cyclic voltammetry. Glassy carbon was used for the working electrode, platinum wire was used for the counter electrode, and silver wire immersed in an acetonitrile solution of AgNO ₃ was used for the reference electrode. Ferrocene is used as the standard substance, and the ionization potential of the compound (A1) based on the oxidation-reduction potential of ferrocene is 0.39 V vs. Fc / Fc ⁺ . This value was equivalent to the ionization potential (0.31 V vs. Fc / Fc ⁺ ) of NPD which has been conventionally known as a hole transport material.

Example 4 (Evaluation of ionization potential of compound (A12))
When the ionization potential of the compound (A12) was evaluated in the same manner as in Example 3, it was 0.38 V vs. Fc / Fc ⁺ , which was equivalent to the ionization potential (0.31 V vs. Fc / Fc ⁺ ) of NPD, which has been conventionally known as a hole transport material.

Example 5 (Element evaluation of compound (A1))
The glass substrate on which the ITO transparent electrode (anode) having a thickness of 200 nm was laminated was subjected to ultrasonic cleaning with acetone and pure water and boiling cleaning with isopropyl alcohol. Furthermore, ultraviolet ozone cleaning was performed, and after installing in a vacuum evaporation apparatus, it exhausted with the vacuum pump until it became ^1x10 <^-4> Pa. First, NPD was deposited on the ITO transparent electrode at a deposition rate of 0.3 nm / second to form a 20 nm hole injection layer. Subsequently, after depositing compound (A1) at a deposition rate of 0.3 nm / second for 30 nm, phosphorous dopant material tris (2-phenylpyridine) iridium (Ir (ppy) ₃ ) and host material 4,4′- Bis (N-carbazolyl) biphenyl (CBP) was co-evaporated at a deposition rate of 0.25 nm / second so that the weight ratio was 1: 11.5 to obtain a 20 nm light emitting layer. Next, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) was deposited at a deposition rate of 0.3 nm / second to form an exciton block layer having a thickness of 10 nm. A quinolinolato) aluminum complex (Alq ₃ ) was deposited at 0.3 nm / second to form a 30 nm electron transport layer. Subsequently, lithium fluoride was deposited as an electron injection layer to a thickness of 0.5 nm at a deposition rate of 0.01 nm / second, and aluminum was further deposited to a thickness of 100 nm at a deposition rate of 0.25 nm / second to form a cathode. In a nitrogen atmosphere, a sealing glass plate was bonded with a UV curable resin to obtain an organic EL element for evaluation. A current of 20 mA / cm ² was applied to the device thus fabricated, and driving voltage and external quantum efficiency were measured. The results are shown in Table 1.

Example 6 (Element Evaluation of Compound (A12))
An organic EL device was produced in the same manner as in Example 5 except that the compound (A1) was changed to the compound (A12). Table 1 shows the driving voltage and the external quantum efficiency when a current of 20 mA / cm ² is applied.

Comparative Example 1
An organic EL device was produced in the same manner as in Example 5 except that the compound (A1) was changed to NPD. Table 1 shows the driving voltage and the external quantum efficiency when a current of 20 mA / cm ² is applied.

Claims (2)

General formula (1)

(In the formula, Ar ^{1 to} Ar ⁴ are each independently an aryl group optionally having a substituent having 6 to 50 carbon atoms, or a heteroaryl optionally having a substituent having 4 to 50 carbon atoms. Ar ¹ and Ar ² and Ar ³ and Ar ⁴ may be bonded to each other to form a ring, and R ¹ and R ² are each independently a straight chain or branched chain having 1 to 12 carbon atoms. Alternatively, it represents a cyclic alkyl group, or a phenyl group, biphenyl group or terphenyl group which may have a substituent, and R ^{3 to} R ¹⁴ each independently represents a hydrogen atom, a halogen atom, or a carbon number of 1 to 12. A linear, branched or cyclic alkyl group, a linear, branched or cyclic alkoxy group having 1 to 12 carbon atoms, an aryl group optionally having a substituent having 6 to 50 carbon atoms, or a carbon number of 4 to 50 A heteroaryl group optionally having a substituent Represented. ^However, Ar 1 to Ar ^4, except carbazolyl group, ^{R 1} and ^{R 2} do not have an amino group as a substituent.)
The biscarbazole compound represented by these. An organic EL device, wherein the biscarbazole compound according to claim 1 is used in at least one of a light emitting layer, a hole transport layer, and a hole injection layer.