JP2001354668A - Benzothiophene derivative and organic electroluminescent element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an organic electroluminescent(EL) element having a high luminous efficiency and a long life, a new compound for constituting the element, a hole transporting material and an organic EL material because there are problems that the hole transporting material used in a conventional organic EL element has a low glass transition point and is poor in thermal stability, the life of the element is short or the like and the hole transportability is insufficient. SOLUTION: This benzothiophene derivative is represented by the general formula (1), wherein, R1 to R9 denote each independently hydrogen atom, a 1-6C alkyl group, a 1-6C alkoxy group, a substituted or an unsubstituted aryl group or a substituted or an unsubstituted heterocyclic group; and the aryl group and heterocyclic group may have a structure in which the aryl group and heterocyclic group are mutually condensed when both are adjacent. The organic EL element uses the benzothiophene derivative.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic electroluminescent device (hereinafter abbreviated as an organic EL device) and a material thereof.

[0002]

2. Description of the Related Art In recent years, an organic EL device has attracted attention as a next-generation full-color flat panel display, and active research and development have been made. The organic EL element is an injection-type light emitting element in which a light emitting layer is sandwiched between two electrodes, and emits light by injecting electrons and holes into the organic light emitting layer and recombining them. The materials used include a low molecular weight material and a high molecular weight material, and both indicate that a high-luminance organic EL element can be obtained.

[0003] There are two types of such organic EL elements. One uses an electron-transporting material to which a fluorescent dye added by CW Tang et al. Is added as a light-emitting layer (J. Appl. Phys., 65, 3610 (1989)). This is a device using a fluorescent dye itself as a light emitting layer (for example, an element described in Appl. Phys. 27, L269 (1988)).

The types using a fluorescent dye as a light emitting layer are roughly classified into three types. The first is a three-layer structure in which the light-emitting layer is sandwiched between an electron transport layer and a hole-transport layer. The second is a three-layer structure in which a hole-transport layer and a light-emitting layer are stacked. The eye is obtained by laminating an electron transport layer and a light emitting layer to form two layers. It is known that the luminous efficiency of the organic EL element is improved by taking such a laminated structure.

[0005] The electron transport layer in the organic EL device having the above-mentioned constitution contains an electron transfer compound, and has a function of transferring electrons injected from the cathode to the light emitting layer. The hole transport layer and the hole injection layer are layers containing a hole transport compound and have a function of transmitting holes injected from the anode to the light emitting layer. By interposing a hole injection layer between the anode and the light emitting layer, many holes are transmitted to the light emitting layer with a lower electric field from the anode, and furthermore, electrons injected from the electron transport layer or the electron injection layer are transferred to the light emitting layer. It is possible to obtain an organic EL device having excellent luminous performance, such as improved luminous efficiency.

However, these organic EL devices do not have sufficient performance for practical use. The major cause is that the durability of the material used is insufficient, and in particular, the durability of the hole transport material is poor. If there is a heterogeneous part such as a grain boundary in the organic layer of the organic EL device,
It is considered that the electric field concentrates on that portion, leading to deterioration and destruction of the element. Therefore, the organic layer is often used in an amorphous state. The organic EL element is an electron injection element, and if the material used has a low glass transition point, heat generated during driving will result in deterioration of the organic EL element. Therefore, the glass transition point (hereinafter, abbreviated as Tg) is obtained. ) Is required. In addition, the hole transporting material used has an insufficient hole transporting property, and the luminous efficiency of the device is not practically sufficient.

As a hole transporting material used in such an organic EL device, although a wide variety of materials centering on a triphenylamine derivative are known, there are few materials suitable for practical use. For example, N, N'-diphenyl-N, N'-di (3-methylphenyl) -4,4'-diaminobiphenyl (hereinafter abbreviated as TPD) has been reported (Appl. Phys. Lett. , 57, 6, 531 (1990))
However, this compound has poor thermal stability and has a problem in the life of the device. U.S. Pat. Nos. 5,047,687, 4,047,948, 4,536,457, JP-B-6-32307, JP-A-5-234681, JP-A-5-239455, and JP-A-8-87.
No. 122 and JP-A-8-259940 also describe many triphenylamine derivatives,
No compound has sufficient properties.

[0008] JP-A-4-308688 and JP-A-6-308688
Starburst amine derivatives described in JP-A-1972 and Adv. Mater., 6, 677 (1994);
-126226, JP-A-7-126615, JP-A-7-331238, JP-A-7-973
No. 55, JP-A-8-48656, JP-A-8-86.
No. 100172 and J. Chem. Soc. Chem. Comm.,
No compound described in 2175, (1996) has practically essential characteristics of high luminous efficiency and long life. Furthermore, Japanese Patent Application Laid-Open No. 9-194441 reports an example using a naphthylamine derivative, and describes that the property is improved from the properties of TPD. Was not enough.

JP-A-4-33918, JP-A-4-33918
93078, JP-A-4-359922, Sy
nth. Mater., 89, 227 (1997), J. Am. Chem. Soc., 12
0, 589 (1998), Chem. Mater., 10, 1487 (1998), Acta.
Chem. Scand., 52, 131 (1998) and Mol. Cryst. Liq.
Cryst., 296, 445 (1997).
It has been clarified that (2-thienyl) phenyl] amine and its polymer have a hole-transporting property, and device characteristics in a configuration in which the above compound is interposed between an anode and a cathode are shown. When the luminance was 100 cd / cm ^2, the applied voltage was 8 V and the current density was 100 mA / cm ² . Also,
The Tg is as low as 70 ° C. and does not have practically sufficient characteristics.

As described above, the hole transporting material used in the conventional organic EL device does not have sufficient performance for practical use, and by using an excellent material, the efficiency and life of the organic EL device can be improved. It is desired to increase. Further, most organic EL devices emit light from a light-emitting layer or an electron transport layer provided separately from the charge transport layer, and rarely from a hole transport layer. The reason for this is that there is a problem of compatibility with the electron transport layer used at the same time, but it is considered that the emission color and emission intensity of the hole transport material itself are also important factors. Although it is expected that the practical value will be higher if light emission can be extracted from the hole transport layer, there are few such materials.
Also, such materials often have long emission wavelengths,
There is a problem that short-wavelength light cannot be extracted.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide an organic EL device having a high luminous efficiency and a long life.
An object is to provide a device, a novel compound used for the device, a hole transport material, and an organic electroluminescent material.

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems of the conventional organic EL device. As a result, the use of a specific benzothiophene derivative has a high Tg, The inventors have found that an organic EL device having high efficiency and long life can be obtained, and have completed the present invention.

That is, the present invention has the following configuration.

(1) A benzothiophene derivative represented by the general formula (1).

Embedded image (Wherein, R _{1 to} R ₉ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group, or a substituted or unsubstituted hetero group. A ring group, and when the aryl group and the heterocyclic group are adjacent to each other, they may have a structure fused to each other.)

(2) An organic electroluminescent device, wherein the benzothiophene derivative according to (1) is used.

(3) The organic electroluminescent device according to (2), wherein the benzothiophene derivative according to (1) is contained in a hole transport layer.

(4) The benzothiophene derivative according to (1) is contained in a light-emitting layer.
The organic electroluminescent device according to (2).

(5) The organic electroluminescent device according to (2), wherein the benzothiophene derivative according to (1) is contained in a hole injection layer.

(6) An organic electroluminescent material comprising the benzothiophene derivative according to (1).

(7) A hole transport material comprising the benzothiophene derivative according to (1).

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Specific examples of the benzothiophene derivative represented by the general formula (1) include compounds represented by the following formulas (2) to (11).

[0022]

Embedded image (In the formula, t-Bu represents a t-butyl group.)

[0023]

Embedded image (In the formula, Me represents a methyl group.)

[0024]

Embedded image (In the formula, Me represents a methyl group.)

These benzothiophene derivatives can be synthesized by performing a coupling reaction between a compound containing a benzothiophene group and a triarylamine halide using a transition metal catalyst. For example, it can be obtained by the method described in the synthesis example of the present specification. The benzothiophene derivative of the present invention emits fluorescence by itself and is suitable as a light emitting material. This is due to the benzothiophene group and the aryl group bonded thereto. In particular,
Since the benzothiophene derivative of the present invention emits blue light, an organic EL device having a different light emission color can be obtained by adding another light-emitting material such as yellow, green, or red.

The organic EL device of the present invention is not only highly efficient but also has high durability during storage and operation.
This is because the benzothiophene derivative represented by the general formula (1) used in the present invention has a high Tg. This benzothiophene derivative can also be used as a material for forming a hole transport layer and a hole injection layer.

The structure of the organic EL device of the present invention has various modes. Basically, the structure is such that an organic layer containing the benzothiophene derivative is sandwiched between a pair of electrodes (anode and cathode). Yes, if desired, the benzothiophene derivative layer may be combined with a hole injection layer, a hole transport layer, a light emitting layer, an electron injection layer or an electron transport layer using another material. When a benzothiophene derivative is used as the light-emitting layer, by adding another light-emitting material to the light-emitting layer, light of a different wavelength can be generated, the light emission efficiency can be improved, and the hole injection material can be improved. Alternatively, when used as a hole transport material, another material can be used in combination to further improve the function.

The specific structure is (1) anode / benzothiophene derivative layer / cathode, (2) anode / benzothiophene derivative layer / light emitting layer / cathode, (3) anode / benzothiophene derivative layer / light emitting layer / cathode. Electron injection layer / cathode, (4)
Anode / hole injection layer / benzothiophene derivative layer / emission layer / electron injection layer / cathode; (5) anode / benzothiophene derivative layer / hole transport layer / emission layer / electron injection layer / cathode;
(6) anode / hole injection layer / benzothiophene derivative layer /
A laminated structure such as an electron injection layer / cathode can be given. In these cases, the hole injection layer and the electron injection layer are not necessarily required, but by providing these layers, the luminous efficiency can be improved.

It is preferable that the organic EL device of the present invention is supported on a substrate in any of the above structures. The substrate only needs to have mechanical strength, thermal stability and transparency, and glass, a transparent plastic film, or the like can be used. Organic EL of the present invention
As the anode material of the device, metals, alloys, electrically conductive compounds, and mixtures thereof having a work function greater than 4 eV can be used. Specific examples include metals such as Au, CuI, and indium tin oxide (hereinafter referred to as ITO).
And a transparent conductive material such as SnO ₂ or ZnO.

As the cathode material, metals, alloys, electrically conductive compounds, and mixtures thereof having a work function of less than 4 eV can be used. Specific examples include aluminum,
There are calcium, magnesium, lithium, magnesium alloy, aluminum alloy and the like, and examples of the alloy include aluminum / lithium fluoride, aluminum / lithium, magnesium / silver, magnesium / indium and the like. In order to efficiently extract the light emitted from the organic EL element,
It is desirable that at least one of the electrodes has a light transmittance of 10% or more. Sheet resistance as electrode is several hundred Ω / mm
It is preferable to set the following. Although the thickness depends on the properties of the electrode material, it is usually 10 nm to 1 μm, preferably 10 nm to 1 μm.
It is selected in the range of 400 nm. Such electrodes are
It can be manufactured by forming a thin film by a method such as evaporation or sputtering using the above-mentioned electrode substance.

The benzothiophene derivative represented by the formula (1) used in the organic EL device of the present invention has a sufficiently high Tg.
Other materials used, such as a light emitting material and an electron injection material, also preferably have a Tg of 80 ° C. or higher, more preferably 100 ° C. or higher.

Other hole injecting materials and hole transporting materials used in the organic EL device of the present invention include those conventionally used as hole charge transporting materials in photoconductive materials, and organic EL devices. Any known materials used in the hole injection layer and the hole transport layer of the device can be selected and used. For example, carbazole derivatives (N-phenylcarbazole, polyvinylcarbazole, etc.), triarylamine derivatives (TPD, polymers having an aromatic tertiary amine in the main chain or side chain,
1,1-bis (4-di-p-tolylaminophenyl) cyclohexane, N, N′-diphenyl-N, N′-dinaphthyl-4,4′-diaminobiphenyl, 4,4 ′, 4 ″
-Tris {N- (3-methylphenyl) -N-phenylamino} triphenylamine, J. Chem. Soc. Chem. Co
mm., 2175 (1996);
JP-A-144558, JP-A-61-62038, JP-A-61-124949, JP-A-61-1
No. 34354, JP-A-61-134355,
JP-A-61-112164, JP-A-4-3086
No. 88, JP-A-6-312979, JP-A-6-312979
-267658, JP-A-7-90256,
JP-A-7-97355, JP-A-6-1972, JP-A-7-126226, JP-A-7-126
615, JP-A-7-331238, JP-A-8-100172 or JP-A-8-48656, Adv. Mater., 6, 677 (19
94), stilbene derivatives (such as those described in The Chemical Society of Japan 72nd Annual Meeting (II), p. 1392, page 2PB098), phthalocyanine derivatives (metal-free, copper-free) Phthalocyanine), polysilane and the like.

The hole injecting layer and the hole transporting layer in the organic EL device of the present invention may be composed of one layer containing one or more of the above-mentioned compounds. It may be a laminate of a plurality of contained layers.

There are no particular restrictions on other electron injecting materials and electron transporting materials used in the organic EL device of the present invention. Among the photoconductive materials, those conventionally used as electron transfer compounds and those of organic EL devices can be used. Any of the known materials used for the electron injection layer and the electron transport layer can be selected and used. Preferred examples of such an electron transfer compound include diphenylquinone derivatives (described in the journal of the Institute of Electrophotography, 30, 3 (1991)) and perylene derivatives (J. Apply. Phys., 27, 269 (198)
8)), oxadiazole derivatives (Jpn. J. Aplly. Phys., 27, L713 (1988)), App
l. Phys. Lett., 55, 1489 (1989), etc.),
Thiophene derivatives (as described in JP-A-4-212286, etc.) and triazole derivatives (Jpn. J. Appl.
Phys., 32, L917 (1993)), thiadiazole derivatives (43th Proceedings of the Society of Polymer Science, (III) P1a
007), metal complexes of oxine derivatives (IEICE Technical Report, 92 (311), 43 (1992)
Etc.), polymers of quinoxaline derivatives (as described in Jpn. J. Appl. Phys., 33, L250 (1994), etc.), and phenanthroline derivatives (43th Polymer Symposium, 14J07) Described)).

Other light-emitting materials used in the light-emitting layer of the organic EL device of the present invention include those described in Polymer Functional Materials Series “Optical Functional Materials” edited by The Society of Polymer Science, Kyodo Shuppan (1991), p.236. Known light-emitting materials such as a daylight fluorescent material, a fluorescent brightener, a laser dye, an organic scintillator, and various fluorescent analysis reagents can be used. Specifically, polycyclic condensed compounds such as anthracene, phenanthrene, pyrene, chrysene, perylene, coronene, rubrene, and quinacridone; oligophenylene-based compounds such as quarterphenyl; 1,4-bis (2-methylstyryl) benzene; , 4-bis (4-methylstyryl) benzene,
1,4-bis (4-phenyl-5-oxazolyl) benzene, 1,4-bis (5-phenyl-2-oxazolyl) benzene, 2,5-bis (5-tert-butyl-2-benzoxazolyl) L) thiophene, 1,4-diphenyl-1,3-butadiene, 1,6-diphenyl-
Scintillator for liquid scintillation such as 1,3,5-hexatriene, 1,1,4,4-tetraphenyl-1,3-butadiene, metal complex of oxine derivative described in JP-A-63-264692, coumarin dye Dicyanomethylenepyran dye, dicyanomethylenethiopyran dye, polymethine dye, oxobenzanthracene dye, xanthene dye, carbostyril dye, and perylene dye, oxazine-based compounds described in DE 2534713, 40th Applied Physics Preferred are stilbene derivatives described in Proceedings of the Conference of Related Alliance Lectures, 1146 (1993), spiro compounds described in JP-A-7-278537, and oxadiazole-based compounds described in JP-A-4-363891.

Each layer constituting the organic EL device of the present invention comprises:
By forming the material to constitute each layer into a thin film by a known method such as an evaporation method, a spin coating method, and a casting method,
Can be formed. The thickness of each layer formed in this way is not particularly limited and can be appropriately selected depending on the properties of the material, and is usually 2 nm to 5000 n.
m. Note that as a method for thinning the benzothiophene derivative, it is preferable to use an evaporation method because a uniform film is easily obtained and a pinhole is not easily generated. When a thin film is formed using an evaporation method, the evaporation conditions vary depending on the type of the benzothiophene derivative, the target crystal structure and the associated structure of the molecular accumulation film, but generally, the boat heating temperature is 50 to 400 ° C., Vacuum degree 10 ^-6 to 10 ^-3 Pa, deposition rate 0.01 to 50 nm /
Seconds, substrate temperature -150 to + 300 ° C, film thickness 5nm to 5μ
It is preferable to select an appropriate value in the range of m.

Next, as an example of a method for producing an organic EL device using the benzothiophene derivative of the present invention, an organic EL device comprising the above-described anode / benzothiophene derivative / cathode is used.
A method for forming the L element will be described. On a suitable substrate, a thin film made of a material for an anode is formed to a thickness of 1 μm or less, preferably
An anode is formed by vapor deposition so as to have a thickness in the range of ~ 200 nm, and then a thin film of a benzothiophene derivative is formed on the anode to form a light emitting layer. 1 μm thin film
The target organic EL element is obtained by forming the cathode to have the following film thickness. In the production of the above-mentioned organic EL device, the production order can be reversed, and the cathode, the light-emitting layer, and the anode can be produced in this order.

When a DC voltage is applied to the organic EL device thus obtained, the anode may be applied with a positive polarity and the cathode may be applied with a negative polarity. Light emission can be observed from the transparent electrode side (anode or cathode, and both). The organic EL element also emits light when an AC voltage is applied. The waveform of the applied alternating current may be arbitrary.

[0039]

Next, the present invention will be described in more detail with reference to examples.

Synthesis Example 1 Synthesis of tris [4- (2-benzothienyl) phenyl] amine (compound represented by formula (2), hereinafter abbreviated as BtP-3) 1.66 g of benzothiophene and t-butyl Put 40 ml of methyl ether in a flask and under a nitrogen atmosphere-
After cooling to 78 ° C., 8.5 ml of a 1.5 mol / L n-butyllithium / n-hexane solution was added dropwise. -1
After the temperature was raised to 0 to −5 ° C., 1.9 ml of N, N, N ′, N′-tetramethylethylenediamine and dichloro (N,
3.43 g of N, N ', N'-tetramethyl-ethylenediamine) zinc was added and heated to room temperature. Next, 2.49 g of phenylamine triiodide and 0.084 g of bis (triphenylphosphine) palladium chloride were added and heated at reflux temperature (56 ° C.) for 2 hours. After the reaction,
After cooling to room temperature, pure water was added, and the organic layer was extracted. It was concentrated by an evaporator and purified by recrystallization from toluene to obtain 1 g of the desired compound.
The emission color of this compound in toluene was blue, and Tg
Was 130 ° C. ¹ H-NMR (CDCl ₃ ) δ = 7.2 (d, 6H), 7.2 (m, 9
H), 7.3-7.4 (m, 6H), 7.5 (s, 3H), 7.6-7.7 (d, 6H),
7.8 (d, d, 6H). In the same manner as in this synthesis example, benzothiophene was replaced with 3-t-butylbenzothiophene to give the compound represented by the formula (3) (tris @ 4- [2 −
(3-t-butylbenzothienyl)] phenyl} amine) is replaced with 3-phenylbenzothiophene by replacing benzothiophene with a compound represented by formula (5) (tris {4- [2- (3-phenylbenzothienyl)). )] Phenyl diamine) can be synthesized respectively.

Example 1 An IT was placed on a 25 mm × 75 mm × 1.1 mm glass substrate.
O deposited to a thickness of 50 nm (Tokyo Sanyo Vacuum Co., Ltd.)
Was used as a transparent support substrate. This transparent support substrate was fixed to a base holder of a commercially available vapor deposition device (manufactured by Vacuum Kiko Co., Ltd.), and a molybdenum vapor deposition boat containing BtP-3 synthesized in Synthesis Example 1, tris (8-hydroxyquinoline) aluminum A molybdenum vapor deposition boat containing (hereinafter abbreviated as ALQ), a molybdenum vapor deposition boat containing lithium fluoride, and a tungsten vapor deposition boat containing aluminum were mounted. 1 × 10 ^-3 vacuum chamber
The pressure was reduced to Pa, and the deposition boat containing BtP-3 was heated, BtP-3 was deposited to a thickness of 50 nm to form a hole transport layer, and then the deposition boat containing ALQ was heated. Then, ALQ was deposited to a thickness of 50 nm to form a light emitting layer. Deposition rate is 0.1-0.2nm
/ Sec. Then, the deposition boat containing lithium fluoride is heated to a thickness of 0.003 to a thickness of 0.5 nm.
Then, the film was deposited at a deposition rate of 0.01 nm / sec.
The organic EL device was obtained by vapor deposition at a vapor deposition rate of 0.2 to 0.5 nm / sec so as to obtain m. Using the ITO electrode as the anode and the lithium fluoride / aluminum electrode as the cathode
When a DC voltage of about 4 V is applied, a current of about 4 mA / cm ² flows, the luminance is about 100 cd / m ² , and the luminous efficiency is 2.1.
Green light having a wavelength of 520 nm was obtained at lm / W. Also,
Although a DC voltage of 6.5 V was continuously applied, light emission was continued even after 3 hours. In addition, no decrease in light emission was observed even when heated to 100 ° C.

Example 2 In the same manner as in Example 1, the transparent support substrate was fixed to the substrate holder of the vapor deposition apparatus, and a molybdenum vapor deposition boat containing BtP-3 synthesized in Synthesis Example 1, N, N′-dinaphthyl Molybdenum deposition boat containing N, N'-diphenyl-4,4'-diaminobiphenyl (hereinafter abbreviated as NPD), molybdenum deposition boat containing ALQ, molybdenum containing lithium fluoride Evaporation boats,
And a tungsten deposition boat containing aluminum. The pressure in the vacuum chamber is reduced to 1 × 10 ⁻³ Pa,
The evaporation boat containing tP-3 was heated to a thickness of 10 nm.
BtP-3 is vapor-deposited to form a hole injection layer, and then the NPD-containing vapor deposition boat is heated to vapor-deposit NPD to a thickness of 50 nm to form a hole transport layer. did. Next, the evaporation boat containing ALQ was heated to deposit ALQ to a thickness of 50 nm to form a light emitting layer. The above deposition rates were 0.1 to 0.2 nm / sec. Then, the deposition boat containing lithium fluoride is heated to a thickness of 0.003 to 0.5 nm.
By vapor deposition at a deposition rate of 0.01 nm / sec, and then heating the deposition boat containing aluminum and depositing at a deposition rate of 0.2 to 0.5 nm / sec to a film thickness of 100 nm, organic An EL device was obtained. When a DC voltage of about 4 V was applied using the ITO electrode as the anode and the lithium fluoride / aluminum electrode as the cathode, a current of about 3 mA / cm ² flowed and the luminance was about 100 cd / m ² .

Example 3 In the same manner as in Example 1, the transparent supporting substrate was placed on the substrate holder of the evaporation apparatus.
And BtP-3 synthesized in Synthesis Example 1 was added thereto.
Molybdenum evaporation boat, molybdenum with NPD
Boat for vapor deposition, 9,9'-spirobisilafluorene
Molybdenum evaporation boat, put lithium fluoride
Molybdenum evaporation boat and aluminum
And the tungsten boat for evaporation. Vacuum chamber
1 × 10 ^-3Depressurized to Pa and deposited boat with NPD
Is heated and NPD is deposited to a thickness of 50 nm.
To form a hole transport layer, and then deposit with BtP-3
Heating boat for BtP to a thickness of 20 nm.
-3 was deposited to form a light emitting layer. Next, 9,9'-s
Heat the evaporation boat containing pyrobisilafluorene,
9,9'-spirobisilafur so that the film thickness becomes 50 nm.
Oren was deposited to form an electron transport layer. Above deposition rate
The degree was 0.1-0.2 nm / sec. After that,
Heating the evaporation boat with titanium, 0.5nm thick
Deposition rate of 0.003 to 0.01 nm / sec.
And then heat the evaporation boat containing aluminum
And a thickness of 0.2 to 0.5 nm
The organic EL element is deposited at a deposition rate of
Obtained. Anode of ITO electrode, lithium fluoride / aluminum
When a DC voltage of 10 V is applied using the electrode as a cathode,
50mA / cm^TwoCurrent flows and blue from BtP-3
Luminescence was obtained.

Example 4 In the same manner as in Example 1, the transparent support substrate was fixed to the substrate holder of the vapor deposition apparatus, and the molybdenum vapor deposition boat containing BtP-3 synthesized in Synthesis Example 1, 4, 4 ', 4 "-Tris {N- (3-methylphenyl) -N-phenylamino}
A molybdenum vapor deposition boat containing triphenylamine, a molybdenum vapor deposition boat containing ALQ, a molybdenum vapor deposition boat containing lithium fluoride, and a tungsten vapor deposition boat containing aluminum were mounted. The pressure in the vacuum chamber is reduced to 1 × 10 ⁻³ Pa, and 4,4 ′,
The vapor deposition boat containing 4 "-tris {N- (3-methylphenyl) -N-phenylamino} triphenylamine is heated so that the film thickness of 4,4 ', 4" -tris @ N is 5 nm. -(3-Methylphenyl) -N-phenylamino} triphenylamine is deposited to form a hole injection layer, and then the deposition boat containing BtP-3 is heated to a thickness of 50 nm. BtP-3 was deposited to form a hole transport layer. Next, the evaporation boat containing ALQ was heated to deposit ALQ to a thickness of 50 nm to form a light emitting layer. The above deposition rate is 0.1 to 0.2
nm / sec. Thereafter, the deposition boat containing lithium fluoride was heated to a thickness of 0.5 nm to a thickness of 0.5 nm.
Deposit at a deposition rate of 03-0.01 nm / sec, then
Heat the deposition boat containing aluminum to a film thickness of 100
An organic EL device was obtained by vapor deposition at a vapor deposition rate of 0.2 to 0.5 nm / sec so that the thickness became nm. When a DC voltage of 3 V was applied using the ITO electrode as the anode and the lithium fluoride / aluminum electrode as the cathode, a current of about 3 mA / cm ² flowed, and green light emission with a luminance of about 100 cd / cm ² was obtained.

Comparative Example 1 The procedure of Example 1 was repeated except that BtP-3 was replaced with NPD.
An organic EL device was prepared in the same manner as in Example 1. I
When a DC voltage of about 4 V is applied using the TO electrode as an anode and the lithium fluoride / aluminum electrode as a cathode, about 4 mA / cm
² flows, luminance is about 100 cd / cm ² , luminous efficiency is 1.9 l
m / W. When heated to 100 ° C., no light emission was observed.

Comparative Example 2 An organic EL device was prepared in the same manner as in Example 1, except that BtP-3 used in Example 1 was replaced with tris [4- (2-thienyl) phenyl] amine. When a DC voltage of about 4 V was applied using the ITO electrode as an anode and the lithium fluoride / aluminum electrode as a cathode, about 20 mA / cm ² flowed. When a DC voltage was applied at 80 ° C., light emission stopped after a few seconds.

[0047]

As described above, the benzothiophene derivative of the present invention has a high Tg of 100 ° C. or higher and tends to be in an amorphous state. By using the organic EL device as a hole injecting material, high efficiency and a long life of the organic EL device can be realized. That is, the organic E of the present invention
In the L element, by using a benzothiophene derivative as an organic layer, high efficiency, long life, and full color can be easily achieved.
Therefore, by using the organic EL device of the present invention, a highly efficient display device such as a full color display can be produced.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05B 33/22 H05B 33/22 D (72) Inventor Kenji Furukawa 5-1 Okawa, Kanazawa-ku, Yokohama-shi, Kanagawa Chisso F-term in Yokohama Laboratory (reference) 3K007 AB03 AB04 AB11 CA01 CB01 DA01 DB03 EB00 4C063 AA05 BB02 BB09 CC94 DD64 EE10

Claims (7)

[Claims] 1. A benzothiophene derivative represented by the general formula (1). Embedded image (Wherein, R _{1 to} R ₉ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group, or a substituted or unsubstituted hetero group. A ring group, and when the aryl group and the heterocyclic group are adjacent to each other, they may have a structure fused to each other.) 2. An organic electroluminescent device, wherein the benzothiophene derivative according to claim 1 is used. 3. The organic electroluminescent device according to claim 2, wherein the benzothiophene derivative according to claim 1 is contained in a hole transport layer. 4. The benzothiophene derivative according to claim 1 is contained in a light emitting layer.
3. The organic electroluminescent device according to claim 1. 5. The organic electroluminescent device according to claim 2, wherein the benzothiophene derivative according to claim 1 is contained in a hole injection layer. 6. An organic electroluminescent material comprising the benzothiophene derivative according to claim 1. 7. A hole transporting material comprising the benzothiophene derivative according to claim 1.