JP6348198B1 - Hole transport compound and organic light emitting device including the same - Google Patents

Abstract

A hole transport compound and an organic light emitting device including the hole transport compound exhibiting characteristics having a long lifetime are provided. A hole transport compound represented by the following formula and an organic light-emitting device including the hole transport compound. (R1 and R2 are each independently a hydrogen atom, a cyano group, a hydroxy group, a thiol group, a halogen atom, a substituted or unsubstituted C1-C14 alkyl group, etc.)

Description

  The present invention relates to a hole transport compound and an organic light emitting device including the hole transport compound, and more particularly, based on high hole transport characteristics, relatively low ionization potential, and crystal formation by introducing an allylamino group into a carbazole core. The present invention relates to a hole transport compound and an organic light-emitting device including the same, which have the characteristics of reducing the ionization potential, improving the hole transport capability by reducing the ionization potential, and having a long life.

  An electroluminescent device (EL element) is a self-luminous display device, and has an advantage of not only a wide viewing angle and excellent contrast but also a quick response time.

  The EL element is classified into an inorganic EL element and an organic EL element according to a material for forming a light emitting layer. Here, the organic EL element has the advantages that the luminance, the driving voltage, and the response speed characteristic are superior to those of the inorganic EL element, and multicolorization is possible.

  A general organic EL device has a structure in which an anode is formed on an upper portion of a substrate, and a hole transport layer, a light emitting layer, an electron transport layer, and a cathode are sequentially formed on the anode. Yes. Here, the hole transport layer, the light emitting layer, and the electron transport layer are organic thin films made of an organic compound.

  The driving principle of the organic EL element having the structure as described above 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 via the hole transport layer. On the other hand, electrons are injected from the cathode into the light emitting layer via the electron transport layer, and carriers recombine in the light emitting layer region to generate excitons. The excitons change from the excited state to the ground state, and the molecules in the light emitting layer emit light, thereby forming an image. Luminescent materials are classified into fluorescent materials that use singlet excitons and phosphorescent materials that use triplet states depending on the emission mechanism.

  Until now, many amine derivatives having a carbazole skeleton have been studied as hole transport materials used in such organic light-emitting devices, but it is very difficult to put to practical use due to higher driving voltage, lower efficiency, and shorter lifetime. Met.

  Accordingly, efforts have been made to develop an organic light emitting device having low voltage driving, high brightness, and long life using a material having excellent characteristics.

Korean Registered Patent Publication No. 10-16163507

  In order to solve the above-mentioned problems, the present invention is based on high hole transport properties, and has a relatively low ionization potential and an allylamino group group introduced into the carbazole core to reduce crystal formation, thereby reducing the ionization potential. An object of the present invention is to provide a hole transport compound and an organic light-emitting device including the hole transport compound, which improve the hole transport ability by reducing the above and exhibit characteristics having a long lifetime.

In order to solve the above-described problems, the present invention provides a hole transport compound represented by the following <Chemical Formula 5 >.

In order to solve the above-described problems, the present invention provides an organic light-emitting device including a hole transport layer between a pair of electrodes, wherein the hole transport layer includes the hole transport compound according to <Chemical Formula 5>. An organic light emitting device is provided.

  The hole transport compound according to the present invention is based on a high hole transfer property, and has a property of relatively lowering the ionization potential and introducing an allylamino group into the carbazole core to reduce crystal formation, thereby reducing the ionization potential and reducing the hole potential. The effect of having a long life can be exhibited by improving the transport capability.

1 is a cross-sectional view illustrating a structure of an organic light emitting device according to an embodiment of the present invention. It is a graph which shows the experimental result with respect to embodiment of this invention. It is a graph which shows the experimental result with respect to embodiment of this invention. It is a graph which shows the experimental result with respect to embodiment of this invention. Figure 3 is NMR data for an embodiment of the present invention. Figure 3 is NMR data for an embodiment of the present invention. Figure 3 is NMR data for an embodiment of the present invention.

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

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to the detailed description of the invention, the terms and words used in the specification and claims to be described below should not be construed as limited to ordinary or lexical meanings. Therefore, the embodiment described in the present specification and the configuration illustrated in the drawings are only the most preferred embodiment of the present invention, and do not represent all the technical ideas of the present invention. It should be understood that there are various equivalents and variations that can be substituted at the time of this application.

  A material or a compound used for the hole transport layer serves as one of light emitting materials in the OLED element.

  Specifically, the hole transport layer has a function of moving the holes transferred through the hole injection layer at the positive electrode more smoothly to the light emitting layer, and binds electrons transferred from the cathode to the light emitting layer. Corresponds to the layer that performs the function.

  On the other hand, the hole transport layer material greatly affects the performance of the OLED element, and the overall performance of the OLED element can be greatly changed depending on how the material is designed and synthesized.

  The basic requirement of the hole transport layer is high hole mobility. In order to exhibit such characteristics, it must have a work function located between the hole injection layer and the light emitting layer, and a low LUMO value is required to constrain electrons to the light emitting layer. When formed, it preferably has amorphous characteristics that do not exhibit crystallinity.

  In addition, the film must have a high glass transition temperature because of its high physical thermal stability, and the film must be translucent in the visible light range so that visible light can pass in the visible light range. I must.

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

  Specifically, in the hole transport compound according to the present invention, the allylamino group was introduced into the carbazole core to reduce crystal formation, and the ionization potential was reduced to improve the hole transport capability.

  In addition, by applying the triphenylamine derivative, a long device lifetime could be secured.

  On the other hand, the hole transport compound according to the present invention having the structure as described above is a conventional carbazole such as a method in which bromobenzene or 4-bromo-1,1′-biphenyl is directly bonded to benzidine to bond a carbazole derivative. In the method for synthesizing the hole transport compound containing, there is a problem that the synthesis is not smooth or the yield is remarkably lowered even if synthesized.

  On the other hand, in the present invention, in order to solve such a problem, a halogen group or an amine group is first introduced into the carbazole derivative, and thereafter, aniline or biphenyl-4-amine is linked, and then 4,4′-dibromo By inducing a coupling reaction using biphenyl, the hole transport compound according to the present invention, which is the target compound, was obtained with a relatively stable yield and high purity.

  Specifically, the hole transport compound according to the present invention has the following structure of <Chemical Formula 1>.

  In the chemical formula, R1 and R2 are each independently a hydrogen atom, a cyano group, a hydroxy group, a thiol group, a halogen atom, a substituted or unsubstituted C1-C14 alkyl group, a substituted or unsubstituted C1- C14 alkoxy group, substituted or unsubstituted C2-C14 alkenyl group, substituted or unsubstituted C6-C14 allyl group, substituted or unsubstituted C7-C14 allylalkyl group, substituted or unsubstituted C6-C14 allyloxy group, substituted or unsubstituted C4-C14 heteroallyl group, substituted or unsubstituted C5-C14 heteroallylalkyl group, substituted or unsubstituted C4-C14 heteroallyloxy group Substituted or unsubstituted C5-C14 cycloalkyl group, substituted or unsubstituted C4-C14 A heterocycloalkyl group, a substituted or unsubstituted C2-C14 alkylcarbonyl group, a substituted or unsubstituted C7-C30 allylcarbonyl group, or a C1-C14 alkylthio group, wherein the heterocycle includes One or more heteroatoms selected from N, O, and S are included.

  Moreover, the hole transport compound according to the present invention has the following structure of <Chemical Formula 4>.

  In the chemical formula, R1 and R2 are each independently a hydrogen atom, a cyano group, a hydroxy group, a thiol group, a halogen atom, a substituted or unsubstituted C1-C14 alkyl group, a substituted or unsubstituted C1- C14 alkoxy group, substituted or unsubstituted C2-C14 alkenyl group, substituted or unsubstituted C6-C14 allyl group, substituted or unsubstituted C7-C14 allylalkyl group, substituted or unsubstituted C6-C14 allyloxy group, substituted or unsubstituted C4-C14 heteroallyl group, substituted or unsubstituted C5-C14 heteroallylalkyl group, substituted or unsubstituted C4-C14 heteroallyloxy group Substituted or unsubstituted C5-C14 cycloalkyl group, substituted or unsubstituted C4-C14 A heterocycloalkyl group, a substituted or unsubstituted C2-C14 alkylcarbonyl group, a substituted or unsubstituted C7-C30 allylcarbonyl group, or a C1-C14 alkylthio group, wherein the heterocycle includes One or more heteroatoms selected from N, O, and S are included.

  The hole transport compounds represented by the above <Chemical Formula 1> and <Chemical Formula 4> have an allylamino group group introduced into the carbazole core to reduce crystal formation, reduce the ionization potential, improve the hole transport capability, By applying the phenylamine derivative, a long device lifetime can be secured.

  The compound according to a preferred embodiment of the present invention can be represented by the following <Chemical Formula 2>, <Chemical Formula 3>, and <Chemical Formula 5>.

  The compound having the structure according to <Chemical Formula 2>, <Chemical Formula 3>, and <Chemical Formula 5> has an advantageous HOMO energy level in hole transport, and has a high LUMO energy level, thereby Can be blocked. Therefore, the compound having a structure according to the above <chemical formula 2>, <chemical formula 3>, and <chemical formula 5> is superior to TAPC, NPB, and BPBPA in which the overall hole transport property is generally used in the hole transport layer, By having high energy efficiency and glass transition temperature, stability and lifetime are also excellent.

  The organic light emitting device according to an embodiment of the present invention is an organic light emitting device including a hole transport layer between a pair of electrodes, and the hole transport layer is the chemical formula 1 to the chemical formula 5 A hole transport compound according to any one of the above.

<Organic light emitting device>
Hereinafter, the structure and manufacturing method of an organic light emitting device employing the phosphorescent host compound according to the present invention will be described.

  The organic light emitting device according to the present invention can adopt the structure of a normal light emitting device, and the structure can be changed as necessary. Basically, the organic light emitting device has a structure including an organic film (light emitting layer) between a first electrode (anode electrode) and a second electrode (cathode electrode), and includes a hole injection layer, a hole transport layer, A hole suppression layer, an electron injection layer, or an electron transport layer may be further included. In order to explain the structure of the light emitting device of the present invention, reference is made to FIG.

  Referring to FIG. 1, the organic light emitting device according to the present invention has a structure including a light emitting layer 50 between an anode electrode 20 and a cathode electrode 80, and a hole injection layer between the anode electrode 20 and the light emitting layer 50. 30 and a hole transport layer 40, and an electron transport layer 60 and an 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 of FIG. 1 according to an embodiment of the present invention is manufactured through the following process, which is a detailed example and is not limited to this method. .

  First, an anode electrode 20 is formed by coating an anode electrode material on the substrate 10. Here, as the substrate 10, a substrate generally used in this field can be used, and in particular, a glass substrate or a transparent plastic substrate excellent in transparency, surface smoothness, ease of handling, and waterproofness is preferable. In addition, as the anode electrode material formed on the substrate, indium tin oxide (ITO), tin oxide (SnO2), zinc oxide (ZnO), etc. that are transparent and excellent in conductivity can be used. It is not limited.

  A hole injection layer (HIL) 30 is selectively formed on the anode electrode 20. At this time, the hole injection layer is formed by a usual method such as vacuum deposition or spin coating. The material for the hole injection layer is not particularly limited, but CuPc (copper phthalocyanine) or IDE 406 (Idemitsu Kosan) can be used.

  Next, the hole transport layer (HTL) 40 is formed on the hole injection layer 30 by an ordinary method such as vacuum deposition or spin coating. Generally, the hole transport layer material is N, N′-diphenyl-N, N′-bis (1-naphthyl) -1,1′-diphenyl-4,4′-diamine (NPB) N. , N′-bis (3-methylphenyl) -N, N′-diphenyl- [1,1-biphenyl] -4,4′-diamine (TPD), N, N′-di (naphthalen-1-yl) -N, N'-diphenylbenzidine, N, N'-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine: α-NPD) and the like can be used. A hole transport compound represented by any one of Chemical Formula 1> to <Chemical Formula 5> is included.

  Next, the light emitting layer (EML) 50 is formed on the hole transport layer 40. The light emitting layer forming material may include one or more selected from phosphorescent host compounds in the light emitting host material, and may have a single layer or a multilayer structure of two or more layers. In this case, the compound of <Chemical Formula 1> may be contained alone or mixed with other compounds known in the art, for example, blue light emitting dopants (iridium compounds such as FIrppy or FIrpic). it can. The phosphorescent host compound may be included in the light emitting layer in the range of 1 to 95% by weight based on the total weight of the materials constituting the light emitting layer.

  The phosphorescent host compound may be formed by a vacuum deposition method, or may be deposited by a wet process such as spin coating, and a laser thermal transfer method (LITI) may be used.

  Optionally, a hole suppression layer (HBL) that stops excitons formed of a light emitting material from moving to the electron transport layer or stops holes from moving to the electron transport layer 60 is formed on the light emitting layer 50. The hole-suppressing layer material is not particularly limited, but a phenanthroline-based compound (for example, BCP) or the like can be used. This can be formed by vacuum deposition or spin coating.

  In addition, an electron transport layer (ETL) 60 may be formed on the light emitting layer 50, and a vacuum deposition method or a spin coating method may be used. Although it does not restrict | limit especially as an electron carrying layer material, TBPI and aluminum complex (For example, Alq3 (Tris (8-quinolinolato) -aluminum)) can be used.

  An electron injection layer (EIL) 70 may be formed on the electron transport layer 60 using a method such as vacuum deposition or spin coating, and the material for the electron injection layer 70 is not particularly limited. However, materials such as LiF, NaCl, and CsF can be used.

  Next, the cathode electrode 80 is formed on the electron injection layer 70 by vacuum deposition, thereby completing the light emitting device. Here, the metal for the cathode includes lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver. (Mg—Ag) or the like is used.

  In addition, the organic light emitting device according to the present invention has a laminated structure as shown in FIG. 1, and it is possible to further form one or two intermediate layers, for example, a hole suppression layer, if necessary. . Further, the thickness of each layer of the light emitting element can be determined as necessary within a range generally used in this field.

  Hereinafter, the present invention will be described in more detail with reference to embodiments, but the present invention is not limited to the following embodiments.

To 30 mL of tetrahydrofuran, 10 g (0.05 mol) of 9H-carbazole is added and brought to 0 ° C., and then 2.88 g (0.12 mol) of sodium hydride is added, followed by stirring for 30 minutes. Add 7.85 g (0.072 mol) of bromoethane to the reaction solution and stir at reflux for 3 hours. After confirming the completion of the reaction, the temperature is brought to room temperature, and then 100 mL of methylene chloride is added to the reaction solution, followed by washing with 20% brine and extraction. The organic layer was treated with anhydrous magnesium sulfate, filtered, and the filtrate was distilled under reduced pressure, and then crystallized with n-hexane to obtain 10.8 g (92.3%) of the target compound 9H-ethyl-carbazole.

To 50 mL of tetrahydrofuran, 20 g (0.1 mol) of 9H-carbazole is added and brought to 0 ° C. Then, 5.76 g (0.24 mol) of sodium hydride is added, followed by stirring for 30 minutes. To the reaction solution, 22.6 g (0.14 mol) of bromobenzene was added and treated by the method as in Synthesis Example 1 to obtain 21.5 g (88.6%) of the target compound 9-phenyl-9H-cover sol.

After adding 12 g (0.061 mol) of ethylcarbazole to 300 ml of N, N-dimethylformamide and dissolving, 10.9 g (0.061 mol) of N-bromosuccinimide was gradually added, and the mixture was stirred at room temperature for 12 hours under a nitrogen atmosphere. did. After confirming the completion of the reaction, 300 mL of water was added, followed by extraction three times with 800 mL of dichloromethane. The organic layer was collected, washed with 200 mL of water, treated with anhydrous magnesium sulfate, filtered, and then concentrated under reduced pressure. The obtained solid was recrystallized from 200 mL of isopropylamine to obtain 14.3 g (84.1%) of the target compound 3-bromo-9-ethyl-9H-carbazole as light brown crystals.

14.8 g (0.061 mol) of 9-phenyl-9H-carbazole was added to 500 ml of N, N-dimethylformamide and dissolved, and then 10.9 g (0.061 mol) of N-bromosuccinimide was gradually added to form a nitrogen atmosphere. Under stirring at room temperature for 12 hours. After confirming the completion of the reaction, 300 mL of water was added, followed by extraction three times with 800 mL of dichloromethane. The organic layer was collected, washed with 200 mL of water, treated with anhydrous magnesium sulfate, filtered, and then concentrated under reduced pressure. The obtained solid was subjected to silica gel chromatography using a mixed solution of dichloromethane and n-hexane 1: 5 as an eluent to obtain 12.7 g (64.7%) of the target compound 3-bromo-9-phenyl-9H-carbazole as light yellow crystals. )

3-Bromo-9-ethyl-9H-carbazole 14.2 g (0.052 mol), bis (pinacolato) diborane 15.7 g (0.062 mol), potassium acetate 10.1 g (0.103 mol) and tetrakistriphenylphosphine palladium (0) 3.4 g (0.003 mol) was dissolved in 1,4-oxane 300 ml, and then heated and stirred at 110 ° C. for 18 hours. After confirming the completion of the reaction, the reaction solution is filtered through silica, 1 L of ethyl acetate is added, and the mixture is extracted while being washed twice with saturated brine, and then once with water. The organic layer is treated with anhydrous magnesium sulfate, filtered, and the organic layer is concentrated under reduced pressure. The residue obtained is chromatographed on silica gel with a mixed solution of dichloromethane and n-hexane 1:10 as an eluent to give the target compound as off-white crystals. 10.4 g (62.2%) of 9-ethyl-3- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9H-carbazole was obtained.

3-Bromo-9-phenyl-9H-carbazole 16.8 g (0.052 mol), bis (pinacolato) diborane 15.7 g (0.062 mol), potassium acetate 10.1 g (0.103 mol) and tetrakistriphenylphosphine palladium (0) 3.4 g (0.003 mol) was dissolved in 1,4-oxane (400 ml), and then treated by the method as in Synthesis Example 5, and a dichloromethane / n-hexane 1: 5 mixed solution was subjected to silica gel chromatography with an eluent. 11.1 g (57.8%) of the desired compound 9-phenyl-3- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9H-carbazole as white crystals )

9-ethyl-3- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9H-carbazole 10.3 g (0.032 mol), 1-bromo-4-iodo After adding 9.05 g (0.032 mol) of benzene and 1.87 g (0.002 mol) of tetrakistriphenylphosphine palladium (0) to 200 ml of tetrahydrofuran, the mixture was stirred for 30 minutes. After adding 200 ml of 2N-potassium carbonate aqueous solution to the reaction solution, it was vigorously stirred at 70 ° C. for 18 hours. After confirming the completion of the reaction, 500 mL of methylene chloride was added to the residue obtained by distillation of the reaction solution under reduced pressure, and after washing several times with water, the organic layer was treated with anhydrous magnesium sulfate, filtered, The residue obtained by concentration under reduced pressure was chromatographed on silica gel with a mixed solution of dichloromethane and n-hexane 1:10 as an eluent to give the target compound 3- (4-bromophenyl) -9-ethyl-9H-carbazole as gray-brown crystals. 6.2 g (55.3%) were obtained.

11.8 g (0.032 mol) of 9-phenyl-3- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9H-carbazole, 1-bromo-4-iodo 11.8 g (0.032 mol) of benzene, 9.05 g (0.032 mol) and 1.87 g (0.002 mol) of tetrakistriphenylphosphine palladium (0) were added to 200 ml of tetrahydrofuran and dissolved, and then Synthesis Example 8 The residue obtained by the above process was chromatographed on silica gel with a mixed solution of ethyl acetate and n-hexane 1: 5 as an eluent to give the target compound 3- (4-bromophenyl) -9-phenyl as white crystals. 8.4 g (65.8%) of -9H-carbazole was obtained.

3- (4-Bromophenyl) -9-ethyl-9H-carbazole 6.2 g (0.018 mol), aniline 1.8 g (0.019 mol), sodium tert-butoxide 1.8 g (0.019 mol) In addition to 150 ml of hydrofuran, the mixture was stirred at room temperature for 30 minutes. After adding a solution of 0.51 g (0.001 mol) of bis (dibenzylideneacetone) palladium (0) in 1.79 g (0.009 mol) of tri-tert-butylphosphine (50% xylene) to the reaction solution, Stir at reflux for 18 hours. After confirming the completion of the reaction, the reaction solution is filtered through silica, 1 L of ethyl acetate is added, and the mixture is extracted while being washed twice with saturated brine, and then once with water. The organic layer is treated with anhydrous magnesium sulfate, filtered, and the organic layer is concentrated under reduced pressure. The residue obtained is chromatographed on silica gel with a mixed solution of dichloromethane and n-hexane 1: 2 as an eluent to give the target compound as white crystals. There were obtained 2.7 g (41.4%) of 4- (9-ethyl-9H-carbazol-3-yl) -N-phenylaniline.

3- (4-Bromophenyl) -9-phenyl-9H-carbazole 10 g (0.025 mol), aniline 2.58 g (0.028 mol), sodium tert-butoxide 2.91 g (0.03 mol) in 100 mL toluene. In addition, it is heated to 60 ° C. A solution containing 3.2 g (0.015 mol) of tri-tert-butylphosphine and 0.72 g of bis (dibenzylideneacetone) palladium (0) was added all at once to the reaction solution, and the mixture was stirred at reflux for 24 hours. After confirming the completion of the reaction, the reaction product was cooled to room temperature, the reaction product was filtered through silica, 200 mL of ethyl acetate was added, washed with water several times, the organic layer was treated with anhydrous magnesium sulfate, filtered, and organic After the layer was concentrated under reduced pressure, the resulting residue was dissolved by adding a small amount of ethyl acetate, and then an excessive amount of 300 mL n-heptane was added, and the resulting crystals were stirred vigorously at 0 ° C. for 1 hour, and the generated crystals were filtered. Thus, 4.2 g (40.6%) of the target compound N-phenyl-4- (9-phenyl-9H-carbazol-3-yl) aniline as white crystals was obtained.

3- (4-Bromophenyl) -9-phenyl-9H-carbazole 10 g (0.025 mol), biphenyl-4-amine 5.1 g (0.030 mol), sodium tert-butoxide 3.62 g (0.038 mol) ) Was added to 150 mL of toluene and stirred at room temperature for 30 minutes. After adding a solution prepared by dissolving 0.72 g (0.0013 mol) of bis (dibenzylideneacetone) palladium (0) in 3.05 g (0.013 mol) of tri-tert-butylphosphine (50% xylene) to the reaction solution, Stir at reflux for 22 hours. After confirming the completion of the reaction, after cooling to room temperature, silica filtration, adding 300 mL of methylene chloride, washing several times with water, treating the organic layer with anhydrous magnesium sulfate, filtering, and then concentrating the organic layer under reduced pressure A small amount of tetrahydrofuran was added to the resulting residue, 500 mL of n-hexane was added, and the resulting crystals were stirred vigorously for 2 hours and filtered to form the target compound N- (4- 6 g (49.1%) of (9-phenyl-9H-carbazol-3-yl) phenyl)-[1,1′-biphenyl] -4-amine were obtained.

2.7 g (0.007 mol) of 4- (9-ethyl-9H-carbazol-3-yl) -N-phenylaniline, 1.1 g (0.004 mol) of 4,4′-dibromobiphenyl and sodium-tert-butoxide 0.78 g (0.008 mol) was dissolved in 80 ml of tetrahydrofuran and then stirred at room temperature for 30 minutes. After raising the temperature of the reaction solution to 40 ° C., a solution of 0.08 g (0.0004 mol) of palladium (II) acetate in 0.75 g (0.004 mol) of tri-tert-butylphosphine (50% xylene) was added. Thereafter, the mixture was stirred at reflux for 30 hours. After cooling the reaction solution to room temperature, the reaction solution is filtered through silica, 1 L of ethyl acetate is added, and the mixture is extracted while being washed twice with saturated brine, and then once with water. The organic layer was treated with anhydrous magnesium sulfate, filtered, and the organic layer was concentrated under reduced pressure. The residue obtained was subjected to silica gel chromatography using a mixed solution of dichloromethane, ethyl acetate and n-hexane 1: 4: 2 as an eluent. Target compound N4, N4′-bis (4- (9-ethyl-9H-carbazol-3-yl) phenyl) -N4, N4′-diphenyl- [1,1′-biphenyl] -4,4 in the form of white crystals 0.9 g (13%) of '-diamine was obtained. FIG. 5 shows the NMR data of the hole transport compound synthesized in this way.

N-phenyl-4- (9-phenyl-9H-carbazol-3-yl) aniline 7.7 g (0.02 mol), 4,4′-dibromo-1,1′-biphenyl 3.17 g (0.01 mol) ), 2 g (0.02 mol) of sodium tert-butoxide is added to 300 ml of toluene and heated to 60 ° C. After adding a solution obtained by dissolving 0.2 g (0.0002 mol) of tris (dibenzylideneacetone) dipalladium (0) in 2 g (0.008 mol) of tri-tert-butylphosphine (50% xylene) to the reaction solution, 24 Stir at reflux for hours. After confirming the completion of the reaction, after cooling to room temperature, silica filtration, adding 500 mL of ethyl acetate, washing several times with water, treating the organic layer with anhydrous magnesium sulfate, filtering, and then reducing the organic layer under reduced pressure A small amount of tetrahydrofuran was dissolved in the residue obtained by concentration, 500 mL of n-heptane was added, and the resulting solid was stirred vigorously at 0 ° C. for 2 hours. , Ethyl acetate, n-hexane 1: 1: 4 mixture was subjected to silica gel chromatography with an eluent to give the target compound N4, N4′-diphenyl-N4, N4′-bis (4- (9-phenyl-9H) as white crystals. -Carbazol-3-yl) phenyl)-[1,1′-biphenyl] -4,4′-diamine 1.5 g (7.7%) was obtained. FIG. 6 shows the NMR data of the hole transport compound synthesized in this way.

  1.3 g (0.004 mol) of 4,4′-dibromobiphenyl, N- (4- (9-phenyl-9H-carbazol-3-yl) phenyl)-[1,1′-biphenyl] -4-amine 4.3 g (0.009 mol) and sodium tert-butoxide 1 g (0.0104 mol) were added to 50 mL of toluene, followed by stirring at room temperature for 30 minutes. After raising the temperature of the reaction solution to 40 ° C., 0.5 g (0.002 mol) of tri-tert-butylphosphine (50% xylene) was added to 0.19 g of tris (dibenzylideneacetone) dipalladium (0). After adding a solution in which 0002 mol) was dissolved, the mixture was stirred at reflux for 30 hours. After confirming the completion of the reaction, after cooling to room temperature, silica filtration, adding 300 mL of methylene chloride, washing several times with water, treating the organic layer with anhydrous magnesium sulfate, filtering, and then concentrating the organic layer under reduced pressure The mixture of dichloromethane, ethyl acetate and n-hexane 1: 1: 2 was chromatographed on silica gel with the eluent to give the target compound N4, N4′-di ([1,1′-biphenyl] -4- Yl) -N4, N4′-bis (4- (9-phenyl-9H-carbazol-3-yl) phenyl)-[1,1′-biphenyl] -4,4′-diamine 2.2 g (47. 3%). FIG. 7 shows the NMR data of the hole transport compound synthesized in this way.

  A compound according to an embodiment of the present invention, for example, a hole transporting compound having the structure of <Chemical Formula 1> to <Chemical Formula 5> can be easily synthesized by an ordinary engineer with reference to Synthesis Examples 1-14. It is something that can be done.

<Experimental result of hole transport compound itself synthesized by Synthesis Examples 12-14>
The representative physical properties of the compounds 1 to 3 produced in the synthesis examples were evaluated, and the results are shown in Table 1 below.

  As shown in Table 1 above, the hole transport compound according to the present invention has a high glass transition temperature, an advantageous HOMO energy level in hole transport, and a high LUMO energy level. Can be confirmed. Further, it can be confirmed that TID corresponds to 500 ° C. or higher and has a characteristic of thinning to about 600 ° C.

  Moreover, the said substance has the advantage which can be manufactured with a high yield by the synthesis examples 1-14 mentioned above.

<Experimental Results of Organic Light-Emitting Element Applying Hole Transport Compound Synthesized in Synthesis Examples 12-14>
<Comparative Example 1>
The ITO substrate was washed after patterning so that the light emitting area was 3 mm × 3 mm. After mounting the substrate in a vacuum chamber, the base pressure is adjusted to 1 × 10 −6 torr, and then PEDOT: PSS is spin coated as a hole injection material on the anode ITO and used as a hole transport layer. Was formed into a film with a thickness of 30 nm using a chemical formula 4,4′-cyclohexylidenebis [N, N-bis (4-methylphenyl) benzamine] (TAPC). Thereafter, 9,9-bis (9-ethyl-9H-carbazol-3-yl) -2,7-dimethyl-9H-thioxanthene 10,10-dioxide (light emitting layer) is formed on the hole transport layer. BPM-B102) and FIrpic as a dopant were formed at a dopant doping concentration of 12% and a thickness of 30 nm, and PCB was vacuum-deposited thereon to form a 10 nm thick hole blocking layer. Next, Alq3 was vacuum-deposited on the electron transport layer to form a film with a thickness of 30 nm, LiF as an electron injection layer was formed with a thickness of 1.0 nm, and then Al as a cathode was formed with a thickness of 100 nm. Then, an organic light emitting device was manufactured by forming a film, and the light emission characteristics were evaluated. The relative changes in current, voltage and luminance were measured in real time to evaluate the lifetime of the device. The results are shown in Table 2 below. It was shown to.

<Comparative example 2>
The ITO substrate was washed after patterning so that the light emitting area was 3 mm × 3 mm. After mounting the substrate in a vacuum chamber, the base pressure is adjusted to 1 × 10 −6 torr, and then PEDOT: PSS is spin coated as a hole injection material on the anode ITO and used as a hole transport layer. The (NPB) chemical formula N, N′-di (1-naphthyl) -N, N′-diphenyl- (1,1′-biphenyl) -4,4′-diamine used in Comparative Example 2 is 30 nm. A film was formed with a thickness. Thereafter, 9,9-bis (9-ethyl-9H-carbazol-3-yl) -2,7-dimethyl-9H-thioxanthene 10,10-dioxide (BPM) is formed on the light emitting layer on the hole transport layer. -B102) and FIrpic as a dopant with a dopant doping concentration of 12% and a thickness of 30 nm, and processed by the method as in Embodiment 1 to evaluate the emission characteristics, and the current, voltage, and luminance The relative change was measured in real time to evaluate the lifetime of the device, and the results are shown in Table 2 below.

<Comparative Example 3>
The ITO substrate was washed after patterning so that the light emitting area was 3 mm × 3 mm. After mounting the substrate in a vacuum chamber, the base pressure is adjusted to 1 × 10 −6 torr, and then PEDOT: PSS is spin coated as a hole injection material on the anode ITO and used as a hole transport layer. (BPBPA) used in Comparative Example 3) Chemical formula N, N, N ′, N ″ -tetra [1,1′-biphenyl] -4-yl]-(1,1′-biphenyl) 4 , 4′-diamine was deposited to a thickness of 30 nm. Thereafter, 9,9-bis (9-ethyl-9H-carbazol-3-yl) -2,7-dimethyl-9H-thioxanthene 10,10-dioxide (BPM) is formed on the light emitting layer on the hole transport layer. -B102) and FIrpic as a dopant with a dopant doping concentration of 12% and a thickness of 30 nm, and processed by the method as in Embodiment 1 to evaluate the emission characteristics, and the current, voltage, and luminance The relative change was measured in real time to evaluate the lifetime of the device, and the results are shown in Table 2 below.

<Embodiment 1>
The ITO substrate was washed after patterning so that the light emitting area was 3 mm × 3 mm. After mounting the substrate in a vacuum chamber, the base pressure is adjusted to 1 × 10 −6 torr, and then PEDOT: PSS is spin coated as a hole injection material on the anode ITO and used as a hole transport layer. N4, N4′-bis (4- (9-ethyl-9H-carbazol-3-yl) phenyl) -N4, N4′-diphenyl- [1,1′-biphenyl]-prepared in Synthesis Example 12 4,4′-diamine was deposited to a thickness of 30 nm. Thereafter, 9,9-bis (9-ethyl-9H-carbazol-3-yl) -2,7-dimethyl-9H-thioxanthene 10,10-dioxide (BPM) is formed on the light emitting layer on the hole transport layer. -B102) and FIrpic as a dopant with a dopant doping concentration of 12% and a thickness of 30 nm, and processed by the method as in Embodiment 1 to evaluate the emission characteristics, and the current, voltage, and luminance The relative change was measured in real time to evaluate the lifetime of the device, and the results are shown in Table 2 below.

<Embodiment 2>
The ITO substrate was washed after patterning so that the light emitting area was 3 mm × 3 mm. After mounting the substrate in a vacuum chamber, the base pressure is adjusted to 1 × 10 −6 torr, and then PEDOT: PSS is spin coated as a hole injection material on the anode ITO and used as a hole transport layer. N4, N4′-diphenyl-N4, N4′-bis (4- (9-phenyl-9H-carbazol-3-yl) phenyl)-[1,1′-biphenyl]-produced in Synthesis Example 13 4,4′-diamine was deposited to a thickness of 30 nm. Thereafter, 9,9-bis (9-ethyl-9H-carbazol-3-yl) -2,7-dimethyl-9H-thioxanthene 10,10-dioxide (BPM) is formed on the light emitting layer on the hole transport layer. -B102) and FIrpic as a dopant with a dopant doping concentration of 12% and a thickness of 30 nm, and processed by the method as in Embodiment 1 to evaluate the emission characteristics, and the current, voltage, and luminance The relative change was measured in real time to evaluate the lifetime of the device, and the results are shown in Table 2 below.

<Embodiment 3>
The ITO substrate was washed after patterning so that the light emitting area was 3 mm × 3 mm. After mounting the substrate in a vacuum chamber, the base pressure is adjusted to 1 × 10 −6 torr, and then PEDOT: PSS is spin coated as a hole injection material on the anode ITO and used as a hole transport layer. N4, N4′-di ([1,1′-biphenyl] -4-yl) -N4, N4′-bis (4- (9-phenyl-9H-carbazole-3-) prepared in Synthesis Example 14 Yl) phenyl)-[1,1′-biphenyl] -4,4′-diamine was deposited to a thickness of 30 nm. Thereafter, 9,9-bis (9-ethyl-9H-carbazol-3-yl) -2,7-dimethyl-9H-thioxanthene 10,10-dioxide (BPM) is formed on the light emitting layer on the hole transport layer. -B102) and FIrpic as a dopant with a dopant doping concentration of 12% and a thickness of 30 nm, and processed by the method as in Embodiment 1 to evaluate the emission characteristics, and the current, voltage, and luminance The relative change was measured in real time to evaluate the lifetime of the device, and the results are shown in Table 2 below.

  As shown in <Table 2>, the hole transport compound according to an embodiment of the present invention has a HOMO energy level that allows easier hole injection than the commonly commercialized TAPC, NPB, and BPBPA materials. It has a high LUMO energy level that can block electrons, has excellent hole transport properties, and has high energy efficiency, high Tg stability and long life when applied to the hole transport layer of organic light emitting devices. I can confirm that.

  FIG. 2 illustrates a graph of wavelength versus normalized EL intensity for Comparative Examples 1 to 3 and Embodiments 1 to 3.

  In FIG. 2, Reference 1 refers to Comparative Example 1, Reference 2 refers to Comparative Example 2, Reference 3 refers to Comparative Example 3, Sample 1 refers to Embodiment 1, Sample 2 refers to Embodiment 2, and Sample 3 refers to Embodiment 3. Called.

  As shown in FIG. 2, it can be confirmed that Comparative Examples 1 to 3 and Embodiments 1 to 3 have a substantially similar relationship between the wavelength and the normalized EL intensity.

  FIG. 3 illustrates a graph of voltage versus luminance for Comparative Examples 1 to 3 and Embodiments 1 to 3.

  In FIG. 3, Reference 1 refers to Comparative Example 1, Reference 2 refers to Comparative Example 2, Reference 3 refers to Comparative Example 3, Sample 12 refers to Embodiment 1, Sample 13 refers to Embodiment 2, and Sample 14 refers to Embodiment 3. .

  As shown in FIG. 3, it can be confirmed that the first to third embodiments have relatively high voltage efficiency as compared with the first to third comparative examples.

  FIG. 4 illustrates a graph of luminance according to time in Comparative Examples 1 to 3 and Embodiments 1 to 3.

  In FIG. 4, Reference 1 refers to Comparative Example 1, Reference 2 refers to Comparative Example 2, Reference 3 refers to Comparative Example 3, Sample 1 refers to Embodiment 1, Sample 2 refers to Embodiment 2, and Sample 3 refers to Embodiment 3. Called.

  As shown in FIG. 4, it can be confirmed that Embodiments 1 to 3 have a relatively high life compared to Comparative Examples 1 to 3.

  As described above, the optimum embodiment has been disclosed in the drawings and specification. The present invention is not limited to the above-described embodiments, and various changes and modifications can be made by persons having ordinary knowledge in the technical field to which the invention belongs without departing from the spirit of the present invention. The true technical protection scope should be determined by the technical idea of the appended claims.

DESCRIPTION OF SYMBOLS 10 Substrate 20 Anode electrode 30 Hole injection layer 40 Hole transport layer 50 Light emitting layer 60 Electron transport layer 70 Electron injection layer 80 Cathode electrode

Claims (2)

A hole transport compound represented by the following <Chemical Formula 5>.
In an organic light emitting device including a hole transport layer between a pair of electrodes,
An organic light emitting device, wherein the hole transport layer comprises the hole transport compound according to claim 1 .