TW202325690A - Hole transfer compound and organic light-emitting diodes using the same - Google Patents

Abstract

The present invention relates to a hole transport compound represented by the following Chemical Formula 1 and an organic light emitting device including the same.

Description

Hole transport compound and organic light-emitting device containing the same

The present invention relates to a hole transport compound and an organic light-emitting device comprising the compound, and more specifically, to a hole transport compound and an organic light-emitting device comprising the compound having the property of ensuring Thermal stability and shape stability, based on high hole transport characteristics to reduce free potential to improve hole transport capabilities, based on high glass transition temperature to obtain long service life and low driving voltage.

As a self-luminous display element, an electroluminescent device (electroluminescent device, hereinafter referred to as "EL element") has the advantages of wide viewing angle, excellent contrast ratio, and fast response time.

EL elements are classified into inorganic EL elements and organic EL elements according to materials for forming an emitting layer (emitting layer). Among them, compared with inorganic EL elements, organic EL elements not only have excellent characteristics such as brightness, driving voltage, and response speed, but also have the advantage of being multicolored.

Generally, an organic EL element has a structure in which 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. Wherein, the hole transport layer, the light emitting layer and the electron transport layer are organic thin films formed of organic compounds.

The driving principle of the organic EL element having the above structure is as follows. 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. On the other hand, electrons are injected from the cathode into the light-emitting layer through the electron-transport layer, and carriers are recombined in the light-emitting layer region to generate excitons. The excitons change from an excited state to a ground state, causing the molecules in the light-emitting layer to emit light to form an image. According to the light emitting mechanism, light emitting materials are classified into fluorescent materials using excitons in a singlet state and phosphorescent materials using triplet states.

So far, many amine derivatives having a carbazole skeleton have been studied for such hole transport materials for organic light-emitting devices, but they are difficult to be practical due to high driving voltage, low efficiency, and short service life. Put into use.

Therefore, ongoing efforts are currently being made to develop organic light-emitting elements with low driving voltage, high luminance, and long service life using materials having excellent characteristics.

＜Prior Art Literature＞ patent documents Patent Document 1: Korean Granted Patent Publication No. 10-1631507

＜The problem that the invention intends to solve＞

In order to solve the above-mentioned problems, an object of the present invention is to provide a hole transport compound and an organic light-emitting device including the compound, which ensure thermal stability and shape stability based on a starburst structure, Based on the high hole transport characteristics, the free potential is reduced to improve the hole transport ability, and the high glass transition temperature is used to obtain the characteristics of long service life and low driving voltage.

＜Technical means to solve problems＞

In order to achieve the above object, the present invention provides a hole transport compound represented by Chemical Formula 1 below. Chemical formula 1:

In the above chemical formula 1, the above-mentioned R ₁ and R ₂ are each independently a derivative of stilamine, diphenylamine, or phenyl-benzofuranamine, and at least one of the above-mentioned R ₁ and R ₂ includes a derivative of stilamine.

In order to achieve the above object, the present invention provides a hole transport compound represented by one of the following chemical formulae. Chemical formula:

In order to achieve the above object, the present invention provides a hole transport compound represented by Chemical Formula 2 below. Chemical formula 2:

In the above chemical formula 2, the above R ₃ and R ₄ are each independently a derivative of stilamine, diphenylamine, or phenyl-benzofuranamine, and at least one of the above R ₃ and R ₄ includes a derivative of stilamine.

In order to achieve the above object, the present invention provides a hole transport compound represented by one of the following chemical formulae. Chemical formula:

In order to achieve the above object, the present invention provides a hole transport compound represented by Chemical Formula 3 below. Chemical formula 3:

In the above chemical formula 3, each of the above-mentioned R5 _{and R6} is benzofurancarbazole or a spirocyclic derivative, and at least one of the above-mentioned _R5 and _R6 contains benzofurancarbazole.

In order to achieve the above object, the present invention provides a hole transport compound represented by one of the following chemical formulae. Chemical formula:

In order to achieve the above object, the present invention provides a hole transport compound represented by one of the following chemical formulae. Chemical formula:

In order to achieve the above object, the present invention provides an organic light-emitting element comprising a hole transport layer between a pair of electrodes, wherein the hole transport layer comprises one of the above chemical formula 1, chemical formula 2, chemical formula 3 or the above chemical formula Indicates the hole transport compound.

＜Efficacy compared with previous technology＞

The hole transport compound of the present invention has the effect of improving the hole transport ability by lowering the free potential on the basis of high hole transport properties, and having high compatibility with other layers of ordinary organic light emitting diode (OLED) elements , and has high glass transition temperature, high hole transport capacity and long service life.

The hole transport compound of the present invention has a starburst structure, and therefore has the effect of ensuring thermal stability and shape stability.

Hereinafter, the present invention will be described in more detail.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Before describing the present invention in detail, the terms or words used in this specification and the scope of protection of the present invention should not be limitedly interpreted with the meanings in common dictionaries. Therefore, the embodiments described in this specification and the structure shown in the accompanying drawings are only the best embodiments of the present invention, and do not represent all technical concepts of the present invention. Therefore, it should be understood that, in At the time of filing this application, there may be various equivalent technical solutions and modification examples replacing them.

The material or compound used for the hole transport layer functions as a kind of light emitting material in the organic light emitting diode element.

Specifically, the hole transport layer is a layer that performs a function of making holes transferred from the anode through the hole injection layer more smoothly move to the light-emitting layer, and confines electrons transferred from the cathode in the light-emitting layer.

On the other hand, the material of the hole transport layer has a great influence on the performance of the organic light emitting diode element, and the overall performance of the organic light emitting diode element can be greatly changed according to how to design and synthesize it.

The basic requirement of the hole transport layer is high hole transport capability. Therefore, in order to exhibit this characteristic, it is preferable to have a work function between the hole injection layer and the light-emitting layer, and in order to bind electrons in the light-emitting layer, a low LUMO value (Lowest Unoccupied Molecular Orbital) is required. When formed In the case of a thin film, it should have non-crystalline characteristics that do not exhibit crystallinity.

And, on the physical level, in order to have high thermal stability for the hole transport layer, the film should have light transmittance in the visible light region, so as to have a high glass transition temperature and allow visible light to pass through the visible light region.

On the other hand, in addition to the physical properties of the hole transport layer itself, it also has high compatibility in the form of combination with the hole injection layer, light-emitting layer and electrode layer, so that the overall efficiency and service life of the organic light-emitting diode element can be improved. Maintain above the specified level.

In order to satisfy the requirements as described above, the hole transport compound of the present invention was developed.

Specifically, the hole transport compound of the present invention is characterized by imparting three-dimensionality to the molecule as a whole and having a starburst structure capable of achieving overall structural stability. At the structural level, the spirocyclyl derivative is used as the core, and thermal stability and shape stability are obtained by introducing various substituents.

On the other hand, the hole transport compound of the present invention makes the above structure into a firm structure, which can be obtained by combining amine derivatives, diphenylamine derivatives, benzofurancarbazole derivatives, benzene Thiophene derivatives or phenyl-benzofuranamine derivatives make the structure combined with the spirocyclic group stronger to obtain a high glass transition temperature and greatly improve the hole transport ability.

Specifically, the hole transport compound of the present invention has the structures of Chemical Formula 1, Chemical Formula 2, and Chemical Formula 3 below. Chemical formula 1:

In the above chemical formula 1, the above-mentioned R ₁ and R ₂ are each independently a derivative of stilamine, diphenylamine, or phenyl-benzofuranamine, and at least one of the above-mentioned R ₁ and R ₂ includes a derivative of stilamine. Chemical formula 2:

In the above chemical formula 2, the above R ₃ and R ₄ are each independently a derivative of stilamine, diphenylamine, or phenyl-benzofuranamine, and at least one of the above R ₃ and R ₄ includes a derivative of stilamine. Chemical formula 3:

In the above chemical formula 3, each of the above-mentioned R5 _{and R6} is benzofurancarbazole or a spirocyclic derivative, and at least one of the above-mentioned _R5 and _R6 contains benzofurancarbazole.

And, the hole transport compound of the present invention has a structure represented by one of the following chemical formulae.

The compound of the present invention having the structure of the above chemical formula has a favorable HOMO energy level in the process of hole transport, and can block the movement of electrons by obtaining a high LUMO energy level.

Therefore, compared with TAPC, NPB, and BPBP, which are usually used as hole transport layers, the compounds with the above chemical structures have better overall hole transport characteristics, and have high energy efficiency and appropriate glass transition temperature. At the same time, they have organic Compatibility and long service life in light-emitting diode components, and thus the overall stability is also excellent. Furthermore, the compound having the above-mentioned chemical structure can ensure thermal stability and shape stability because it has a starburst structure with a spirocyclic derivative as a core.

And, the hole transport compound of the embodiment of the present invention is used as a compound for the hole transport layer, and the hole transport layer is a layer performing the following function, that is, making the holes transferred from the anode through the hole injection layer more smoothly Move to the light-emitting layer, and at the same time, the electrons transferred from the cathode are bound in the light-emitting layer.

The basic requirement of the hole transport layer (HTL) is to have high hole transport capability, therefore, holes should be efficiently injected from the anode to the light emitting layer (EML).

Such a material is known as an aromatic amine material having an amine structure. It is necessary to form a thin film that does not crystallize during the evaporation process of the material, and to have high thermal stability and contact with the anode. Excellent property/flatness, and when forming a thin film in the visible light region, it should be transparent.

In the present invention, thermal stability and shape stability can be obtained by combining at least one stilamine, diphenylamine, benzofurancarbazole, benzothiophene or phenyl-benzofuranamine to the core structure of the spirocyclic derivative sex. Specifically, as shown in an embodiment of the present invention, a starburst structure is formed by combining stilamine, diphenylamine or phenyl-benzofuranamine around the spirocyclic base core, so that it can have thermal stability and shape stability Moreover, excellent hole transport ability can be obtained.

The compounds of the above-described embodiments of the present invention may be represented by one of the following chemical formulae.

In this structure, there is at least one of tertiarylamine derivatives, diphenylamine, benzofurancarbazole, benzothiophene, or phenyl-benzofuranamine around the core, and therefore, the longest effective co- Yoke maximized structure.

When at least one of tertiarylamine, diphenylamine, benzofurancarbazole, phenyl-benzofurylamine, or benzothiophene is formed around the core core containing the spirocyclic group to form a starburst molecular structure, excellent longest valid conjugate. Organic Light Emitting Components

Hereinafter, the structure and production method of an organic light-emitting device using the hole transport compound of the present invention will be described.

The organic light-emitting element of the present invention can adopt a common light-emitting element structure, and the structure can be changed according to requirements. Generally, an organic light-emitting element has a structure including an organic film (light-emitting layer) between a first electrode (anode electrode) and a second electrode (cathode electrode), and may further include a hole injection layer, a hole transport layer, a hole blocking layer, electron injection layer or electron transport layer. Hereinafter, the structure of the light-emitting element of the present invention will be described with reference to FIG. 1 .

1, the organic light-emitting element of the present invention has a structure including a light-emitting layer 50 between the anode electrode 20 and the cathode electrode 80, and includes a hole injection layer 30 and a hole transport layer 40 between the anode electrode 20 and the light-emitting layer 50. , and the electron transport layer 50 and the electron injection layer 70 are included between the light emitting layer 50 and the cathode electrode 80 .

On the other hand, the organic light-emitting device according to an embodiment of the present invention shown in FIG. 1 is prepared through the following process, but this method is only an example and is not limited thereto.

First, the anode electrode 20 is formed by applying a substance for an anode electrode on the upper portion of the substrate 10 . Among them, the substrate 10 can be a substrate commonly used in the technical field of the present invention, especially, a glass substrate or a transparent plastic substrate with excellent transparency, surface smoothness, ease of handling and water resistance is preferably used. In addition, transparent and highly conductive indium tin oxide (ITO), tin oxide (SnO ₂ ), zinc oxide (ZnO), and the like can be used as the anode electrode material formed on the above-mentioned substrate, but is not limited thereto.

A hole injection layer (HIL) 30 is selectively formed on the above-mentioned anode electrode 20 . In this case, the hole injection layer can be formed by common methods such as vacuum evaporation or spin coating. Copper phthalocyanine (CuPc) or IDE406 (Idemitsu Kosan Co., Ltd.) can be used as the substance for the hole injection layer, and it is not particularly limited.

Next, the hole transport layer 40 is formed on the hole injection layer 30 by common methods such as vacuum evaporation or spin coating. Typically, N,N'-diphenyl-N,N'-di(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), N,N' -bis(3-methylbenzene)-N,N'-diphenyl-[1,1-biphenyl]-4,4'-diamine (TPD), N,N'-bis(naphthalene-1 -yl)-N,N'-diphenylbenzidine, N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (α-NPD), etc. as the hole The substance for the transport layer, however, the embodiment of the present invention includes the hole transport compound of the above chemical formula.

Subsequently, the light emitting layer 50 is formed on the hole transport layer 40 . One or more light-emitting host substances selected from phosphorescent host compounds may be included as a material for forming the above-mentioned light-emitting layer, and may have a single-layer or multi-layer structure of two or more layers. In this case, the compound of Chemical Formula 1 may be contained alone, or may be mixed with other compounds known in the technical field of the present invention, for example, a blue light-emitting dopant (iridium compound such as FIrppy or FIrpic) and the like may be mixed. With respect to the total weight of the components of the light-emitting layer, the above-mentioned light-emitting layer may contain 1% by weight to 95% by weight of the phosphorescent host compound.

The above phosphorescent host compound can be formed by vacuum evaporation method, and can be evaporated by wet coating process such as spin coating, or by laser induction thermal imaging (LITI).

A hole blocking layer (HBL) may be formed on the above-mentioned light-emitting layer 50, and the above-mentioned hole blocking layer (HBL) is used to prevent excitons formed in the light-emitting material from moving to the electron transport layer or to prevent holes from moving to the electron transport layer 60. . A phenanthroline compound (for example, BCP) or the like can be used as the substance for the hole blocking layer, and is not particularly limited. It can be formed by methods such as vacuum evaporation or spin coating.

Furthermore, an electron transport layer 60 can be formed on the light emitting layer 50, which can be formed by methods such as vacuum evaporation or spin coating. TBPI, aluminum complexes (eg, ALq3 (tris(8-quinolinolato)aluminum)) can be used as the material for the electron transport layer without particular limitation.

The electron injection layer 70 can be formed on the upper part of the above-mentioned electron transport layer 60 by methods such as vacuum evaporation or spin coating, and materials such as lithium fluoride (LiF), sodium chloride (NaCl), and cesium fluoride (CsF) can be used as The material for the electron injection layer 70 is not particularly limited.

Next, the cathode electrode 80 is formed on the electron injection layer 70 by vacuum evaporation to complete the light emitting element. In this case, lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg -Ag) etc. as the cathode metal.

Moreover, the organic light-emitting element of the present invention has a laminated structure as shown in FIG. 1 , and a single-layer or double-layer intermediate layer can be formed according to requirements, for example, a hole blocking layer can also be additionally formed. In addition, the thickness of each layer of the light-emitting element can be determined according to requirements within the usual range of the technical field to which the present invention pertains.

Hereinafter, the present invention will be further described in detail through examples, but the present invention is not limited to the following examples. Synthesis example of the hole transport compound of the present invention < Synthesis Example 1> Synthesis of N-([1,1'- biphenyl ]-4- yl )-9,9'- dimethyl -9H - fennel -2-amine

21.55 g (85.80 mmol) of 9,9-dimethyl-9H- tertiary-2-amine and 12.37 g (128.70 mmol) of sodium tert-butoxide were added to 300 mL of toluene, and stirred for 30 minutes to dissolve. 20.0 g (85.80 mmol) of 4-bromo-1,1'-biphenyl was added dropwise thereto, followed by stirring at a temperature of 50° C. for 1 hour. A solution of 0.49 g (0.86 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 1.04 mL (2.15 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:2 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 16.2 g (55.2%) of N-([1,1'- [Phenyl]-4-yl)-9,9'-dimethyl-9H-tilene-2-amine. < Synthesis Example 2> N-([1,1'- biphenyl ]-4- yl )-N-(9,9- dimethyl -9H- oxene -2- yl )-9,9'- spirobiphenyl -4- amine Synthesis

Mix 8.05g (22.26mmol) of N-([1,1'-biphenyl]-4-yl)-9,9'-dimethyl-9H-oxene-2-amine and 2.92g (30.36mmol) of Sodium tert-butoxide was added to 80 mL of toluene, and stirred for 30 minutes to dissolve. 8.0 g (20.24 mmol) of 4-bromo-9,9'-spirobilocene was added dropwise thereto, followed by stirring at a temperature of 50° C. for 1 hour. A solution of 0.12 g (0.20 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 0.25 mL (0.51 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:4 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 7.2 g (52.6%) of N-([1,1'- [Phenyl]-4-yl)-N-(9,9-dimethyl-9H-oxene-2-yl)-9,9'-spirobioxane-4-amine. ＜ Synthesis Example 3＞ The _ _ _ _ _ _ _ _ _ _ _ _ _ synthesis

Mix 8.05g (22.24mmol) of N-([1,1'-biphenyl]-4-yl)-9,9'-dimethyl-9H-oxene-2-amine and 2.92g (30.36mmol) of Sodium tert-butoxide was added to 80 mL of toluene, and stirred for 30 minutes to dissolve. 8.0 g (20.24 mmol) of 4-bromo-9,9'-spirobilocene was added dropwise thereto, followed by stirring at a temperature of 50° C. for 1 hour. A solution of 0.12 g (0.20 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 0.25 mL (0.51 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:4 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 8.1 g (59.2%) of N-([1,1'- [Phenyl]-4-yl)-N-(9,9-dimethyl-9H-fluorene-2-yl)-9,9'-spirobixene-2-amine. < Synthesis Example 4> Synthesis of 5,5-(5- bromo -1,3- phenylene ) bis (5H- benzofuro [3,2-c] carbazole )

16.35 g (63.53 mmol) of 5H-benzofuro[3,2-c]carbazole and 9.16 g (95.30 mmol) of sodium tert-butoxide were added to 100 mL of toluene, and stirred for 30 minutes to dissolve. 10.0 g (31.77 mmol) of 1,3,5-tribromobenzene was added dropwise thereto, and stirred at a temperature of 50° C. for 1 hour. A solution of 0.18 g (0.32 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 0.39 mL (0.79 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:7 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 2.9 g (13.7%) of 5,5-(5-bromo-1 ,3-phenylene)bis(5H-benzofuro[3,2-c]carbazole). < Synthesis Example 5> Synthesis of 5,5'-(5-(9,9'- spirodifen -2- yl )-1,3- phenylene ) bis (5H- benzofuro [3,2-c] carbazole )

2.8g (4.19mmol) of 5,5-(5-bromo-1,3-phenylene)bis(5H-benzofuro[3,2-c]carbazole) and 1.81g (5.03mmol) of 9,9'-spirobioxane-2-ylboronic acid and 0.12 g (0.11 mmol) of tetrakis(triphenylphosphine)palladium(0) were added to 50 mL of tetrahydrofuran, dissolved, and stirred for 30 minutes. 50 mL of 2N-aqueous potassium carbonate solution was added to the reaction solution, followed by vigorous stirring at a temperature of 80° C. for 18 hours. After confirming the completion of the reaction, 500 mL of dichloromethane was added to the residue obtained by distilling the reaction solution under reduced pressure, and the residue was washed with water several times, and the organic layer was treated with anhydrous magnesium sulfate and filtered. Subsequently, using a 1:5 mixed solution of dichloromethane and n-hexane as an eluent, the residue obtained by concentrating the organic layer under reduced pressure was subjected to silica gel chromatography to obtain the target compound, namely, 3.2 g (84.4%) of 5,5'-(5-(9,9'-spirodifen-2-yl)-1,3-phenylene)bis(5H-benzofuro[3,2-c]carbazole).< Synthesis Example 6> Synthesis of 5-(3,5- dibromophenyl )-5H- benzofuro [3,2-c] carbazole

8.17 g (31.77 mmol) of 5H-benzofuro[3,2-c]carbazole and 4.58 g (47.65 mmol) of sodium tert-butoxide were added to 100 mL of toluene, and stirred for 30 minutes to dissolve. 10.0 g (31.77 mmol) of 1,3,5-tribromobenzene was added dropwise thereto, and stirred at a temperature of 50° C. for 1 hour. A solution of 0.18 g (0.32 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 0.39 mL (0.79 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:7 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 3.0 g (19.2%) of 5-(3,5-dibromobenzene base)-5H-benzofuro[3,2-c]carbazole. < Synthesis Example 7> 5-(3-(9,9'- spirodifen -2- yl )-5-(9,9' -spirodifuran -3- yl ) phenyl )-5H- benzofuran [3,2- c] Synthesis of carbazole

2.9g (5.90mmol) of 5-(3,5-dibromophenyl)-5H-benzofuro[3,2-c]carbazole and 2.55g (7.09mmol) of 9,9'-spirobi Perylene-2-ylboronic acid and 0.17 g (0.15 mmol) of tetrakis(triphenylphosphine)palladium(0) were added and dissolved in 50 mL of tetrahydrofuran, and stirred for 30 minutes. To the reaction solution was added 50 mL of 2N-aqueous potassium carbonate solution, and vigorously stirred at a temperature of 80° C. for 18 hours. After confirming the completion of the reaction, 500 mL of dichloromethane was added to the residue obtained by distilling the reaction solution under reduced pressure, and the residue was washed with water several times, and the organic layer was treated with anhydrous magnesium sulfate and filtered. Subsequently, using a 1:4 mixed solution of dichloromethane and n-hexane as an eluent, the residue obtained by concentrating the organic layer under reduced pressure was subjected to silica gel chromatography to obtain the target compound, that is, 4.9 g (86.2%) of 5-(3 -(9,9'-spirobixa-2-yl)-5-(9,9'-spirobixa-3-yl)phenyl)-5H-benzofuro[3,2-c]carbazole . < Synthesis Example 8> Synthesis of N-(3- dibenzo [b,d] furan -1- yl ) phenyl )-9,9- dimethyl - 9H- oxene -2- amine

23.31 g (111.39 mmol) of 9,9-dimethyl-9H- tertiary-2-amine and 13.38 g (139.24 mmol) of sodium tert-butoxide were added to 300 mL of toluene, and stirred for 30 minutes to dissolve. 30.0 g (92.83 mmol) of 1-(3-bromophenyl)dibenzo[b,d]furan was added dropwise thereto, followed by stirring at a temperature of 50° C. for 1 hour. A solution of 0.53 g (0.93 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 1.13 mL (2.32 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:4 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, that is, 37.6 g (89.7%) of N-(3-dibenzo[b ,d] furan-1-yl)phenyl)-9,9-dimethyl-9H-tertil-2-amine. < Synthesis Example 9> N-(3-( Dibenzo [b,d] furan -1- yl ) phenyl )-N-(9,9- Dimethyl -9H- Oxen -2- yl )-9,9' - spiro Synthesis of Dioxane -4- amine

17.82g (39.47mmol) of N-(3-dibenzo[b,d]furan-1-yl)phenyl)-9,9-dimethyl-9H-oxene-2-amine and 4.74g ( 49.33 mmol) of sodium tert-butoxide was added to 200 mL of toluene, and stirred for 30 minutes to dissolve. 13.0 g (32.89 mmol) of 4-bromo-9,9'-spirobistilbene was added dropwise thereto, followed by stirring at a temperature of 50° C. for 1 hour. A solution of 0.19 g (0.33 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 0.40 mL (0.82 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:4 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 21.3 g (84.5%) of N-(3-(dibenzo[ b,d] furan-1-yl)phenyl)-N-(9,9-dimethyl-9H-fluorene-2-yl)-9,9'-spirobixene-4-amine. < Synthesis Example 10> N-(3-( Dibenzo [b,d] furan -1- yl ) phenyl )-N-(9,9- Dimethyl -9H- Oxen -2- yl )-9,9' - spiro Synthesis of dioxane -2- amine

17.82g (39.47mmol) of N-(3-dibenzo[b,d]furan-1-yl)phenyl)-9,9-dimethyl-9H-oxene-2-amine and 4.74g ( 49.33 mmol) of sodium tert-butoxide was added to 200 mL of toluene, and stirred for 30 minutes to dissolve. 13.0 g (32.89 mmol) of 2-bromo-9,9'-spirobistilbene was added dropwise thereto, followed by stirring at a temperature of 50° C. for 1 hour. A solution of 0.19 g (0.33 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 0.40 mL (0.82 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:4 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 20.6 g (81.8%) of N-(3-(dibenzo[ b,d] furan-1-yl)phenyl)-N-(9,9-dimethyl-9H-fluorene-2-yl)-9,9'-spirobixene-2-amine. < Synthesis Example 11> Synthesis of Bis ([1,1'- biphenyl ]-4- yl ) amine

26.13 g (154.44 mmol) of [1,1′-biphenyl]-4-amine and 18.55 g (193.05 mmol) of sodium tert-butoxide were added to 300 mL of toluene, and stirred for 30 minutes for dissolution. 30.0 g (128.70 mmol) of 4-bromo-1,1'-biphenyl was added dropwise thereto, followed by stirring at a temperature of 50° C. for 1 hour. A solution of 0.74 g (1.29 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 1.56 mL (3.22 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, silica filtration was performed and cooled to normal temperature. Subsequently, the target compound, ie, 25.3 g (61.2%) of bis([1,1′-biphenyl]-4-yl)amine was obtained by filtering the generated crystals. < Synthesis Example 12> Synthesis of 2'-(7- bromo -9,9- dimethyl -9H- fluorene -2- yl )-9,9'- spirobistilbene

10.0g (28.40mmol) of 2,7-dibromo-9,9-dimethyl-9H-stilbene, 12.28g (34.09mmol) of 9,9'-spirobis-2-ylboronic acid and 0.82g Tetrakis(triphenylphosphine)palladium(0) (0.71 mmol) was added to 150 mL of tetrahydrofuran, dissolved, and stirred for 30 minutes. 150 mL of 2N-aqueous potassium carbonate solution was added to the reaction solution, followed by vigorous stirring at a temperature of 80° C. for 18 hours. After confirming the completion of the reaction, 500 mL of dichloromethane was added to the residue obtained by distilling the reaction solution under reduced pressure, followed by washing with water several times, and the organic layer was treated with anhydrous magnesium sulfate and filtered. Subsequently, using a 1:4 mixed solution of dichloromethane and n-hexane as an eluent, the residue obtained by concentrating the organic layer under reduced pressure was subjected to silica gel chromatography to obtain the target compound, that is, 6.3 g (37.7%) of 2'-( 7-Bromo-9,9-dimethyl-9H-fluorene-2-yl)-9,9'-spirobistilbene. < Synthesis Example 13> 7-(9,9'- Spiroxane -2- yl )-N,N- bis ([1,1'- biphenyl ]-4- yl )-9,9- Dimethyl -9H- oxalane -2 - Synthesis of amines

3.94 g (12.25 mmol) of bis([1,1'-biphenyl]-4-yl)amine and 1.47 g (15.32 mmol) of sodium tert-butoxide were added to 80 mL of toluene, and stirred for 30 minutes to dissolve . 6.0g (10.21mmol) of 2'-(7-bromo-9,9-dimethyl-9H-oxa-2-yl)-9,9'-spirobistilbene was added dropwise thereto, and at 50°C Stir at temperature for 1 hour. A solution of 0.06 g (0.10 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 0.12 mL (0.26 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:2 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 4.1 g (48.5%) of 7-(9,9'-spirovene -2-yl)-N,N-bis([1,1'-biphenyl]-4-yl)-9,9-dimethyl-9H-oxene-2-amine. < Synthesis Example 14> Synthesis of 2-(9,9'- spirodifen -2- yl )-8- bromodibenzo [b,d] thiophene

10.0g (29.24mmol) of 2,8-dibromodibenzo[b,d]thiophene, 12.64g (35.08mmol) of 9,9'-spirobis-2-ylboronic acid and 0.84g (0.73mmol ) of tetrakis(triphenylphosphine)palladium(0) was added to 150 mL of tetrahydrofuran, dissolved and stirred for 30 minutes. 150 mL of 2N-aqueous potassium carbonate solution was added to the reaction solution, followed by vigorous stirring at a temperature of 80° C. for 18 hours. After confirming the completion of the reaction, 500 mL of dichloromethane was added to the residue obtained by distilling the reaction solution under reduced pressure, followed by washing with water several times, and the organic layer was treated with anhydrous magnesium sulfate and filtered. Subsequently, using a 1:5 mixed solution of dichloromethane and n-hexane as an eluent, the residue obtained by concentrating the organic layer under reduced pressure was subjected to silica gel chromatography to obtain the target compound, that is, 6.8 g (40.3%) of 2-(9 ,9'-spirobifen-2-yl)-8-bromodibenzo[b,d]thiophene. < Synthesis Example 15> 8-(9,9'- Spiroxa -2- yl )-N,N- bis ([1,1'- biphenyl ]-4- yl ) dibenzo [b,d] thiophen -2- amine synthesis

4.34 g (13.51 mmol) of bis([1,1'-biphenyl]-4-yl)amine and 1.62 g (16.88 mmol) of sodium tert-butoxide were added to 100 mL of toluene, and stirred for 30 minutes to dissolve . Add 6.5g (11.26mmol) of 2-(9,9'-spirobioxa-2-yl)-8-bromodibenzo[b,d]thiophene dropwise and stir at 50°C 1 hour. A solution of 0.06 g (0.11 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 0.14 mL (0.28 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:4 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 4.0 g (43.4%) of 8-(9,9'-spirovene -2-yl)-N,N-di([1,1'-biphenyl]-4-yl)dibenzo[b,d]thiophen-2-amine. < Synthesis Example 16> Synthesis of 4- ( 9,9'- spirodiperol -2- yl) -2- bromodibenzo [b,d] furan

10.0g (26.81mmol) of 2-bromo-4-iododibenzo[b,d]furan, 9.66g (26.81mmol) of 9,9'-spirobis-2-ylboronic acid and 0.77g (0.67 mmol) of tetrakis(triphenylphosphine)palladium(0) was added to 200 mL of tetrahydrofuran, dissolved and stirred for 30 minutes. 200 mL of 2N-aqueous potassium carbonate solution was added to the reaction solution, followed by vigorous stirring at a temperature of 80° C. for 18 hours. After confirming the completion of the reaction, 500 mL of dichloromethane was added to the residue obtained by distilling the reaction solution under reduced pressure, followed by washing with water several times, and the organic layer was treated with anhydrous magnesium sulfate and filtered. Subsequently, using a 1:6 mixed solution of dichloromethane and n-hexane as an eluent, the residue obtained by concentrating the organic layer under reduced pressure was subjected to silica gel chromatography to obtain the target compound, that is, 7.4 g (49.2%) of 4-(9 ,9'-spirobifen-2-yl)-2-bromodibenzo[b,d]furan. < Synthesis Example 17> 4-(9,9'- spirodifen -2- yl )-N,N- bis ([1,1'- biphenyl -4- yl ] dibenzo [b,d] furan -2- amine synthesis

4.81 g (14.96 mmol) of bis([1,1'-biphenyl]-4-yl)amine and 1.80 g (18.70 mmol) of sodium tert-butoxide were added to 100 mL of toluene, and stirred for 30 minutes to dissolve . Add 7.0g (12.47mmol) of 4-(9,9'-spirobis-2-yl)-2-bromodibenzo[b,d]furan dropwise and stir at 50°C 1 hour. A solution of 0.07 g (0.12 mmol) of bis(dibenzylideneacetone)palladium(0) dissolved in 0.15 mL (0.31 mmol) of tri-tert-butylphosphine was added to the reaction solution, and the reaction was carried out at a temperature of 100°C. 18 hours. After confirming the completion of the reaction, the mixture was cooled to normal temperature and subjected to silica filtration, and the filtrate was distilled off under reduced pressure. Using a 1:4 mixed solution of dichloromethane and n-hexane as an eluent, the resulting residue was subjected to silica gel chromatography to obtain the target compound, namely, 5.5 g (55.0%) of 4-(9,9'-spirobis fen-2-yl)-N,N-bis([1,1'-biphenyl-4-yl]dibenzo[b,d]furan-2-amine.

Those skilled in the art to which the present invention pertains can easily synthesize the aforementioned compounds of the present invention with reference to the aforementioned Synthesis Example 1 to Synthesis Example 17. Experimental results of the hole transport compounds (compounds 1 to 9 ) synthesized from synthesis example 2 to synthesis example 17

The representative properties of Compounds 1 to 9 (Synthesis Examples 2 to 17) prepared in the above Synthesis Examples were evaluated, and the results are shown in Table 1 below.

Table 1 physical properties UVmax PLmax HOMO LUMO Energy gap T1 TID Tg unit (nm) (nm) (eV) (eV) (eV) (eV) (℃) (℃) Compound 1 (Synthesis Example 2) 269344 410 5.47 2.24 3.23 2.58 406 145 Compound 2 (Synthesis Example 3) 363 408 5.32 2.17 3.15 2.53 436 136 Compound 3 (Synthesis Example 5) 268305345 408 5.56 2.19 3.37 2.50 508 148 Compound 4 (Synthesis Example 7) 271303 382 5.66 2.49 3.17 2.35 240 140 Compound 5 (Synthesis Example 9) 338 411 5.45 2.21 3.24 2.61 425 192 Compound 6 (Synthesis Example 10) 343 438 5.32 2.17 3.15 2.56 443 193 Compound 7 (Synthesis Example 13) 302370 438 5.22 2.47 3.02 2.29 470 173 Compound 8 (Synthesis Example 15) 330 420 5.52 2.23 3.29 2.48 482 177 Compound 9 (Synthesis Example 17) 327 456 5.53 2.28 3.25 2.49 484 162 UVmax: the absorption wavelength of the substance measured by spectrometer and cyclic voltammetry PLmax: the emission wavelength of the substance measured by spectrometer and cyclic voltammetry HOMO, LUMO, energy gap: measured by spectrometer and cyclic voltammetry T1: film form Triplet energy (confirmed by phosphorescence measurement at 77K) TID: degradation temperature of the substance (confirmed by TGA) Tg: glass transition temperature

As shown in the above Table 1, it can be confirmed that the hole transport compound of the embodiment of the present invention has a relatively high glass transition temperature as a whole, and has a HOMO energy level and a high LUMO energy level that are favorable for hole transport.

In addition, it has the advantage that the above-mentioned substance can be prepared in high yield through the above-mentioned synthesis example. Experimental results of organic light-emitting devices using the hole transport compounds (Compounds 1 to 8 ) synthesized in Synthesis Example 2 to Synthesis Example 15 . ＜ Comparative example ＞

The ITO substrate was cleaned after patterning so as to have a light emitting area of 3 mm×3 mm. Subsequently, after installing the substrate in a vacuum chamber, a film of BPBPA: 3% p-dopant (10nm)/BPBPA (35nm) was formed on the anode ITO through a base pressure of 1×10 ^-6 torr as a hole transport layer , NDP-9 from Novaled Company was used as p-dopant. Subsequently, an electron blocking layer (10nm) was formed on the above-mentioned hole transport layer, and DBTTP1 and Ir(ppy)3 were used as dopants to form a film with a thickness of 30nm as the light-emitting layer, wherein the doping concentration of the dopant 10%. Vacuum-deposit ZADN on top of it to form a film with a thickness of 30nm as an electron transport layer. After forming a film with a thickness of 1.5nm with lithium fluoride (LiF) as an electron injection layer, a film with a thickness of 200nm is formed with aluminum as a cathode. The organic light-emitting element was prepared, and then the light-emitting characteristics of the light-emitting element were evaluated, and the service life of the element was evaluated by measuring the relative changes of current, voltage and brightness in real time. The results are shown in Table 2 below.

As the aforementioned p-dopants, TCNQ, MoO ₃ , NDP-2, NDP-9, and the like can be used. <Example> _ _

The ITO substrate was cleaned after patterning so as to have a light emitting area of 3 mm×3 mm. Subsequently, after installing the substrate in a vacuum chamber, substances composed of compound 1 to compound 8 were formed above the anode ITO through a base pressure of 1×10 ^-6 torr: 3%p-dopant (10nm)/compound 1 A film of a substance (35nm) composed of compound 8 was used as a hole transport layer, and NDP-9 from Novaled was used as a p-dopant. Subsequently, an electron blocking layer (10nm) was formed on the above-mentioned hole transport layer, and DBTTP1 and Ir(ppy)3 were used as dopants to form a film with a thickness of 30nm as the light-emitting layer, wherein the doping concentration of the dopant 10%. Vacuum-deposit ZADN on top of it to form a film with a thickness of 35nm as an electron transport layer. After forming a film with a thickness of 1.5nm with lithium fluoride (LiF) as an electron injection layer, a film with a thickness of 200nm is formed with aluminum as a cathode. The organic light-emitting element was prepared, and then the light-emitting characteristics of the light-emitting element were evaluated, and the service life of the element was evaluated by measuring the relative changes of current, voltage and brightness in real time. The results are shown in Table 2 below.

The layer structure of the above elements is shown below. Comparative example: ITO/Reference: 3% p-dopant (10nm)/Reference (35nm)/EBL (10nm)/GH:GD (30nm)/ETL (35nm)/LiF (1.5nm)/Al (200nm) Example 1: ITO/compound 1: 3% p-dopant (10nm)/compound 1 (35nm)/EBL (10nm)/GH:GD (30nm)/ETL (35nm)/LiF (1.5nm)/Al (200nm) Example 2: ITO/compound 2: 3% p-dopant (10nm)/compound 2 (35nm)/EBL (10nm)/GH:GD (30nm)/ETL (35nm)/LiF (1.5nm)/Al (200nm) Example 3: ITO/compound 3: 3% p-dopant (10nm)/compound 3 (35nm)/EBL (10nm)/GH:GD (30nm)/ETL (35nm)/LiF (1.5nm)/Al (200nm) Example 4: ITO/compound 5: 3% p-dopant (10nm)/compound 5 (35nm)/EBL (10nm)/GH:GD (30nm)/ETL (35nm)/LiF (1.5nm)/Al (200nm) Example 5: ITO/compound 6: 3% p-dopant (10nm)/compound 6 (35nm)/EBL (10nm)/GH:GD (30nm)/ETL (35nm)/LiF (1.5nm)/Al (200nm) Example 6: ITO/compound 7: 3% p-dopant (10nm)/compound 7 (35nm)/EBL (10nm)/GH:GD (30nm)/ETL (35nm)/LiF (1.5nm)/Al (200nm) Example 7: ITO/compound 8: 3% p-dopant (10nm)/compound 1 (35nm)/EBL (10nm)/GH:GD (30nm)/ETL (35nm)/LiF (1.5nm)/Al (200nm)

Table 2 Project (Device) Turn On Voltage (V _{turn On} ) (V) Voltage (V) Quantum efficiency (η _ext ) (%) Current efficiency (η _c ) (cd/A) Power efficiency (η _p ) (lm/W) Service life (Lifetime) (h) Color Coordinates (CIE)(x,y) 1000 brightness maximum value 1000 brightness maximum value 1000 brightness maximum value LT90 3000 brightness comparative example 3.0 4.4 14.4 16.0 50.9 56.9 36.3 38.5 14.6 (0.30,0.63) Example 1 3.0 4.3 16.7 17.5 58.9 62.0 43.3 43.4 27.0 (0.30,0.63) Example 2 3.0 3.9 16.0 16.6 56.8 58.6 45.4 46.0 33.2 (0.30,0.63) Example 3 3.6 5.3 13.0 13.3 45.9 46.8 27.5 29.3 28.4 (0.30,0.63) Example 4 2.8 4.3 18.3 18.9 64.9 66.9 47.5 48.8 44.0 (0.30,0.63) Example 5 2.6 4.1 16.9 17.2 60.0 61.0 46.0 46.9 57.6 (0.30,0.63) Example 6 2.7 4.0 14.9 14.9 52.7 53.0 41.1 41.6 33.5 (0.30,0.63) Example 7 2.8 4.2 16.4 17.1 58.1 60.4 43.9 44.7 25.0 (0.30,0.63)

As shown in Table 2, compared with the commonly used BPBPA material, the hole transport compound of an embodiment of the present invention has a HOMO energy level that makes hole injection easy, a high LUMO energy level that can block electrons, and excellent hole Transport characteristics, therefore, it can be seen that high energy efficiency can be obtained when an organic light-emitting element is applied to a hole transport layer.

In particular, in the case of applying the hole transport compound of the embodiment of the present invention, the device can obtain a relatively low driving voltage.

As above, the preferred embodiment in the specification has been disclosed with reference to the attached drawings. But, the present invention is not limited to above-mentioned embodiment, and those with ordinary knowledge in the technical field of the present invention can carry out various changes and modifications without departing from the scope of spirit of the present invention, therefore, the true technical protection scope of the present invention should be based on this The technical concept of the patent scope of the invention application shall be defined.

10: Substrate 20: anode electrode 30: Hole injection layer 40: Hole transport layer 50: luminescent layer 60: Electron transport layer 70: Electron injection layer 80: cathode electrode

FIG. 1 is a cross-sectional view showing the structure of an organic light emitting element of an example of the present invention.

10: Substrate

20: anode electrode

30: Hole injection layer

40: Hole transport layer

50: luminous layer

60: Electron transport layer

70: Electron injection layer

80: cathode electrode

Claims (8)

A hole transport compound represented by the following chemical formula 1: Chemical formula 1: , In the above chemical formula 1, the above-mentioned R ₁ and R ₂ are each independently a derivative of stilamine, diphenylamine, or phenyl-benzofuranamine, and at least one of the above-mentioned R ₁ and R ₂ includes a derivative of stilamine. The hole transport compound as claimed in item 1, wherein the compound is represented by one of the following chemical formulas: . A hole transport compound represented by the following chemical formula 2: Chemical formula 2: , In the above chemical formula 2, the above-mentioned R ₃ and R ₄ are each independently a derivative of stilamine, diphenylamine, or phenyl-benzofuranamine, and at least one of the above-mentioned R ₃ and R ₄ includes a derivative of stilamine. The hole transport compound as claimed in item 3, wherein the compound is represented by one of the following chemical formulas: . A hole transport compound represented by the following chemical formula 3: Chemical formula 3: , In the above chemical formula 3, the above-mentioned R ₅ and R ₆ are each benzofurancarbazole or a spirocyclic derivative, and at least one of the above-mentioned R ₅ and R ₆ contains benzofurancarbazole. The hole transport compound as claimed in item 5, wherein the compound is represented by one of the following chemical formulas: . A hole transport compound represented by one of the following chemical formulas: . An organic light-emitting element comprising a hole transport layer between a pair of electrodes, wherein the hole transport layer comprises the hole transport compound described in any one of claims 1 to 7.

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