KR20200034447A - An electron transport compound, an organic photo-electric device including the same, and an electronic device thereof - Google Patents

Abstract

The present invention is an electron transport material for forming an electron transport layer (ETL) disposed between a first electrode and a second electrode of an organic electroluminescent device, which comprises at least two or more styrene functional groups at ends thereof. The electron transport material according to an embodiment of the present invention can improve the solubility of a low molecular weight organic compound with low solubility.

Description

Electron transport material, organic electroluminescent device including the same, and its electronic device {AN ELECTRON TRANSPORT COMPOUND, AN ORGANIC PHOTO-ELECTRIC DEVICE INCLUDING THE SAME, AND AN ELECTRONIC DEVICE THEREOF}

The present invention relates to an electron transport material, an organic electroluminescent device comprising the same, and an electronic device thereof.

In general, the organic light emitting phenomenon refers to a phenomenon that converts electrical energy into light energy using an organic material. An organic electric device using an organic light emitting phenomenon usually has a structure including an anode and a cathode and an organic material layer therebetween. Here, the organic material layer is often composed of a multi-layer structure composed of different materials in order to increase the efficiency and stability of the organic electric device, and may be formed of, for example, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer.

Materials used as the organic material layer in the organic electric device may be classified into light emitting materials and charge transport materials, such as hole injection materials, hole transport materials, electron transport materials, and electron injection materials, depending on function.

The term 'organic electric element' used in the present invention, an organic integrated circuit (OIC), an organic field-effect transistor (OFET), an organic thin film transistor (OTFT), an organic light emitting transistor (OLET), an organic solar cell (OSC), It is defined as including an organic photodetector, an organic photoreceptor, an organic field-quench device (OFQD), an organic light emitting electrochemical cell (OLEC), an organic laser diode (O-laser) and an organic electroluminescent device (OLED).

In particular, the present invention is interested in providing a new organic compound that forms an electron transport layer of an organic electroluminescent device referred to as OLED. The general structure of OLEDs and their functional principles are well known to those skilled in the art and are particularly described in US 4539507, US 5151629, EP 0676461 and WO 1998/27136.

An organic photoelectric device (OLED), which is drawing attention as a next-generation display device, forms an organic light emitting layer between a cathode and a substrate coated with a transparent cathode material such as ITO, and when a predetermined voltage is applied to the electrode, it is injected from holes and cathodes injected from the anode. It is a device using the principle that electrons combine in the organic light emitting layer to emit light. OLEDs are becoming increasingly popular as they are applied to electronic devices such as flat panel displays, lighting and backlighting. OLED technology is described in Geffroy et al., “Organic Light Emitting Diode (OLED) Technology: Material Device and Display Technology”, Polym, Int., 55: 572-582 (2006), US Pat. Nos. 5,844,363, 6,303,238 and It is described in the various OLED materials and configurations described in 5,707,745, all of which are incorporated herein by reference.

The organic electroluminescent device (OLED) has a multi-layered structure including a charge injection layer according to the characteristics of the hole injection layer, the hole transport layer, the electron transport layer, the electron injection layer and the light emitting layer, in addition to the organic light emitting layer, in order to realize industrially applicable levels of performance. It is made of.

In the prior art, each layer constituting the organic light emitting device (OLED) is generally formed by a vacuum deposition process. Japanese Patent Laid-Open No. 2006-156847 (Patent Document 1) discloses a technique for manufacturing an organic electroluminescent device (OLED) including an organic film having a single-layer structure by depositing it on a substrate by a vacuum deposition method. The vacuum deposition method is a principle of forming a thin film by sublimating heat by applying heat to a sample in a high vacuum atmosphere of 10 ^-4 Torr or less, and subliming the sample to grow as a solid on a relatively low temperature substrate. However, the vacuum deposition method has a large evaporation apparatus, is not easy to install, must maintain a vacuum during the process, has a high process temperature, and particularly uses a mask for a pattern, resulting in high material consumption, low productivity, and high manufacturing cost. Therefore, it is difficult to manufacture an organic light emitting diode (OLED) in a large area.

In order to solve this problem, research into forming an organic thin film through a low-cost solution process has been continuously conducted. The solution process has the disadvantage of not having high resolution compared to the vacuum deposition process, but since it can be manufactured at atmospheric pressure and atmospheric temperature, a separate vacuum device is not required, and since the material consumption rate is low, productivity is high and manufacturing cost is low. The advantage is that it can be large-sized.

The types of solution processes include spin coating, inkjet coating, screen printing, spray coating, roll-to-roll coating, and blade coating. Specific examples of the method and apparatus for manufacturing a large area organic thin film based on a solution process are disclosed in Korean Patent Publication No. 2016-0069799, Korean Patent Registration No. 10-1618395, Korean Patent Publication No. 2017-0066703, It is detailed in Korean Patent Registration No. 10-1618395, Korean Patent Publication No. 2016-0141127 and Korean Patent Publication No. 2016-0138845. In addition, thermal printing techniques and devices that can be used include, for example, US Patent Application Publications US 2008/0311307 A1, US 2008/0308037 A1, US2006 / 0115585 A1, US 2010/0188457 A1, US 2011/0008541 A1, US 2010 / 0171780 A1, and those described in US 2010/0201749 A1, the entire contents of which are incorporated herein by reference.

However, when a multilayer organic film for an organic electric device is coated using a solution process, there is a problem that the organic thin film of the lower layer is damaged by the organic solvent contained in the organic compound of the upper layer, and thus it is difficult to form a multilayer thin film. In order to solve this, an organic compound having a functional group capable of crosslinking must be used, and known crosslinking groups are acrylate and oxetane. However, these crosslinking groups require a high crosslinking temperature for the crosslinking reaction, making it difficult to use a plastic substrate. In addition, in the case of ultraviolet crosslinking, there is a disadvantage in that a photoinitiator is used or a byproduct is generated, which causes problems in the life and efficiency of the organic electric device.

Accordingly, new organic compounds that can produce a multi-layered organic electrical device without dissolving adjacent layers when applying a solution process have been developed by the present inventors. First, Republic of Korea Patent Publication No. 2017-0035228 (Patent Document 2) is an organic device having a solubility in a hydrophilic solvent by bonding an alcohol-based functional group to the ends of a carbazole-based compound and a triphenylamine-based compound having excellent charge transport properties Provided compound, Republic of Korea Patent Publication No. 2017-0117812 (patent document 3) is capable of hydrogen bonding, novel hole blocking and / or electron transport low molecule having at least two or more substituents containing a pyrimidine ring Provided compound, Republic of Korea Patent Publication No. 10-1789672 (Patent Document 4) is a pyrimidine ring having a property capable of hydrogen bonding to the end of the carbazole-based compound comprising a carbazole having a transport and transport characteristics It is equipped with a functional group comprising, excellent in solubility in various solvents, the pyrimidine ring at a predetermined temperature condition It provides an organic light-emitting compound capable of forming a stable organic thin film by inducing hydrogen bonds during the functional period.

JP 2006-156847 A KR 2017-0035228 A KR 2017-0117812 A KR 10-1789672 B1

"Organic light-emitting diode (OLED) technology: material device and display technology", Polym, Int., 55: 572-582 (2006)

The technical problem to be achieved by the present invention is to provide a new electron transport material excellent in efficiency and lifespan characteristics, which is suitable for a solution process because it is capable of crosslinking at a low temperature of about 180 ° C. and does not generate byproducts.

In particular, another object of the present invention is to provide an organic thin film for an electron transport layer of an organic electroluminescent device that is crosslinked through heating at a temperature of about 180 ° C. and does not dissolve in an organic solvent.

In addition, another object of the present invention is to provide an organic electroluminescent device including an organic thin film for such an electron transport layer and an electronic device (or electronic device) including the organic electroluminescent device.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the following description. There will be.

The first aspect of the present invention for achieving the above technical problem is an electron transport material for forming an electron transport layer (ETL) disposed between the first electrode and the second electrode of the organic light emitting device, the electron transport material is It is characterized by containing at least two styrene groups (styrene functional group) at its ends.

In addition, the second aspect of the present invention is an ink composition for forming an electron transport layer (ETL) disposed between the first electrode and the second electrode of the organic light emitting device, wherein the ink composition has at least two or more styrenes at its ends. Characterized in that it comprises an electron transport material containing a group (styrene functional group).

The ink composition may be a solution or suspension further comprising a solvent, and may further include a pigment or dye.

A third aspect of the present invention is an organic electroluminescent device comprising a plurality of organic thin film layers including a light emitting layer and an electron transport layer (ETL) stacked between a cathode and an anode, an electron transport material for forming the electron transport layer (ETL) It is characterized in that it contains at least two styrene groups (styrene functional group) at its end.

Crosslinking is formed between the styrene functional groups at the ends of the electron transport material forming the electron transport layer (ETL).

The organic thin film layer may include at least one selected from the group consisting of a hole injection layer, a hole transport layer, an electron injection layer, an electron blocking layer, and a hole blocking layer. In addition, the organic thin film layer is characterized in that the ink composition containing the organic compound is prepared by coating and drying by a solution process to form a film.

The organic electroluminescent device according to an exemplary embodiment of the present invention has a structure in which an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer and a cathode are sequentially stacked.

The fourth aspect of the present invention is an electronic device including the organic electroluminescent device according to the third aspect of the present invention.

A fifth aspect of the present invention is a method of forming an electron transport layer (ETL) using an electron transport material containing at least two styrene functional groups at its ends, (1) the electron transport material as a solvent Dissolving in to prepare a solution; (2) preparing a substrate including a plurality of organic thin film layers on which at least an electrode and a light emitting layer are formed; (3) applying the solution of step (1) on the substrate; (4) characterized in that it comprises the step of forming an organic thin film layer by heat-treating the substrate coated with the solution for a predetermined time to form cross-linking between styrene functional groups.

At this time, the heat treatment temperature is preferably 180 ℃.

The step (3) is spin coating, gravure offset printing, reverse offset printing, screen printing, roll-to-roll printing, slot die coating, immersion coating, spray coating, doctor blade coating, any one method selected from the group consisting of inkjet coating It is characterized by consisting of.

A sixth aspect of the present invention is a method of manufacturing an organic light emitting device, comprising: (1) preparing a substrate; (2) forming an anode on top of the substrate; (3) forming a hole injection layer on the anode; (4) forming a hole transport layer on top of the hole injection layer; (5) forming a light emitting layer on top of the hole transport layer; (6) forming an electron transport layer on the light emitting layer; (7) forming a cathode on the top of the electron transport layer; including, but, the electron transport layer of step (6) using the method of forming the electron transport layer (ETL) according to the fifth aspect of the present invention It is characterized by.

The method further includes forming a hole blocking layer between steps (5) and (6), or further comprising forming an electron injection layer between steps (6) and (7). You can.

Since the electron transport material according to an embodiment of the present invention has at least two styrene groups at its ends, it is possible to improve the solubility of a low-molecular-weight organic compound having low solubility and productivity as the solubility is improved. Multi-layer structure through the first effect that can be applied to this high solution process, the second effect that when two or more styrene groups are included in the core material, a stable organic thin film can be formed by cross-linking of the styrene period Even if the organic thin film layer is formed, it has a third effect that it is possible to fabricate a device having a stable multi-layer structure without a phenomenon in which adjacent layers are dissolved by a solution, and a fourth effect that a large area and low cost of an organic device are possible.

The electron transport material according to the present invention can improve solubility in various solvents by providing a styrene group capable of crosslinking. In addition, in the prior art, due to the problem of poor solubility of the low molecular organic compound, an organic thin film was mainly formed through a deposition process, and the organic compound according to the present invention can provide properties suitable for various solution processes by improving solubility.

In addition, in the prior art, even if an organic thin film is formed through a solution process, there is a problem that must be performed under high temperature conditions to form a stable organic thin film. However, the organic compound according to the present invention is not only excellent in solubility in a solvent, but also can produce a heat-stable thin film through a low-temperature process of about 180 ° C by cross-linking the styrene period provided in the compound, thereby mass-producing organic devices. , It can enable large area and low cost.

It should be understood that the effects of the present invention are not limited to the above-described effects, and include all effects that can be deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 is an NMR graph of an electron transport material (SMH-E-10) according to an embodiment of the present invention.
FIG. 2 is a UV / Vis spectrum graph of before / after solvent immersion of an organic thin film containing an electron transport material (SMH-E-10) according to an embodiment of the present invention.
3A is a graph showing current-voltage characteristics of an organic light emitting device according to an embodiment of the present invention, and FIG. 3B is a graph showing current-voltage characteristics of an organic EL device according to a comparative example.
Figure 4a is a graph showing the current efficiency according to the change in the current density of the organic light emitting device according to an embodiment of the present invention, Figure 4b is a current efficiency according to the change in the current density of the organic light emitting device according to the comparative embodiment It is a graph to show.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be implemented in various different forms, and thus is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part is "connected (connected, contacted, coupled)" to another part, this is not only when it is "directly connected", but also "indirectly" with another member in between. "It also includes the case where it is. Also, when a part is said to “include” a certain component, this means that other components may be further provided instead of excluding the other component unless otherwise stated.

The terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “include” or “have” are intended to indicate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, and that one or more other features are present. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

 Terms used in the specification are only used to describe a specific embodiment (sun, 態 樣, aspect) (or embodiment), and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as ~ include ~ or ~ consist of ~ are intended to designate the existence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, actions, components, parts or combinations thereof are not excluded in advance. Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings and chemical formulas.

In general, the organic light emitting device (OLED) is a light emitting layer (EML), hole injection layer, hole transport layer, electron injection layer, electron transport layer (ETM), electron blocking layer and hole blocking layer (HBL) between the anode and the cathode An organic thin film functional layer may be included.

For example, the positive electrode may be any one of indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide (ZnO) as an electrode for injecting holes. The hole injection layer may serve to facilitate the injection of holes from the anode to the light emitting layer, and CuPc (cupper phthalocyanine), PEDOT (poly (3,4) -ethylenedioxythiophene), PANI (polyaniline) and NPD (N, N) -dinaphthyl-N, N'-diphenyl benzidine), but is not limited thereto.

The emission layer may emit red (R), green (G), and blue (B), and may be made of a phosphorescent material or a fluorescent material. When the emission layer is red, it includes a host material including CBP (carbazole biphenyl) or mCP (1,3-bis (carbazol-9-yl), PIQIr (acac) (bis (1-phenylisoquinoline) acetylacetonate iridium), PQIr (acac) (bis (1-phenylquinoline) acetylacetonate iridium), PQIr (tris (1-phenylquinoline) iridium), and PtOEP (octaethylporphyrin platinum). Alternatively, it may be made of a fluorescent material including PBD: Eu (DBM) 3 (Phen) or Perylene, but is not limited thereto.When the light emitting layer 140 is green, a host material including CBP or mCP is included. And, it may be made of a phosphor containing a dopant material containing Ir (ppy) 3 (fac tris (2-phenylpyridine) iridium), or, alternatively, a fluorescent material containing Alq 3 (tris (8-hydroxyquinolino) aluminum) It may be made of, but is not limited to. When the light-emitting layer is blue, it may be made of a phosphor material including a dopant material including a (4,6-F2ppy) 2Irpic, including a host material including CBP or mCP, or, alternatively, spiro-DPVBi, spiro- It may be made of a fluorescent material including any one selected from the group consisting of 6P, distylbenzene (DSB), distriarylene (DSA), PFO-based polymer and PPV-based polymer, but is not limited thereto.

The electron injection layer serves to facilitate the injection of electrons, and Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq or SAlq can be used, but is not limited thereto.

The cathode is an electron injection electrode, and may be made of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag), or an alloy thereof having a low work function. Here, the anode may be formed to a thickness thin enough to transmit light when the organic light emitting device is a front or both sides light emitting structure, or to reflect light when the organic light emitting device is a back light emitting structure. It can be thickened.

The present invention is interested in providing a new organic compound (hereinafter referred to as an electron transport material) forming the electron transport layer of the above-described organic electroluminescent device. That is, the electron transport material according to the present invention is characterized by including at least two or more styrene functional groups at the ends of the core material having an electron transport function.

As the core material having the electron transport function, various known materials can be used as long as it can perform a function for smoothly transporting / transporting electrons, and is not limited to the specific embodiments listed below.

In the present specification, the following [Chemical Formula 1] is illustrated as a preferred electron transport material of the present invention.

Referring to [Chemical Formula 1], at least two styrene functional groups are included at the ends of the core material having an electron transport function.

These electron transport materials can be formed at a temperature of about 180 ° C. to form crosslinks of adjacent styrene functional periods. In the case of an organic thin film made of an organic compound in which crosslinking is formed, since it is not dissolved in an organic solvent of an adjacent organic thin film layer, even if a multi-layered thin film is laminated through a solution process, the thin film is not damaged, so that a large-area multi-layered organic electroluminescent device It is optimized for making.

In one embodiment of the present invention, core materials having an electron transport function for forming an organic thin film for an organic light emitting device capable of forming a styrene functional group at a terminal are specifically listed as follows. The materials listed below are merely illustrative of various applications that can be applied to the present invention, and therefore, the present invention is not necessarily limited to the examples indicated below.

(1) pyridine derivatives

(2) Oxadiazole group

(3) azole group

(4) Benzimidizole group

(5) metalchelate

(6) Six-membered heterocycle

(7) Silole-based material

In another embodiment of the present invention, there is provided an ink composition comprising the above-mentioned electron transport material having at least two or more styrene functional groups at the terminal according to the present invention.

The ink composition may be a solution or a suspension containing a solvent, and the solvent may be, for example, anisole, dimethyl anisole, xylene, o-xylene, m-xylene, p-xylene, toluene, mesitylene, methyl Benzoate, dioxane, tetrahydrofuran, methyl tetrahydrofuran, tetrahydropyran, tetralin, veratrol, chlorobenzene, N-methyl pyrrolidone, N, N-dimethylformamide, dimethylsulfoxide and combinations thereof It may include one selected from the group consisting of.

After applying the ink composition, a solvent may be removed to form an organic thin film layer. The ink composition may further include a pigment or dye.

In another embodiment of the present invention, in the organic electroluminescent device in which an organic thin film layer including at least a light emitting layer and an electron transport layer is stacked in multiple layers between a cathode and an anode, the electron transport layer includes at least two or more styrene groups at the ends. It is characterized by consisting of an organic compound.

The electron transport layer may be prepared by forming a film in a solution process using the above-described ink composition containing the electron transport material according to the present invention. This solution process includes any method selected from the group consisting of spin coating, gravure offset printing, reverse offset printing, screen printing, roll-to-roll printing, slot die coating, immersion coating, spray coating, doctor blade coating, inkjet coating. do.

The organic electroluminescent device according to the present invention may be prepared in the order of anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode, and vice versa cathode / electron injection layer / electron transport layer / It may be manufactured in the order of a hole blocking layer / light emitting layer / hole transporting layer / hole injection layer / anode.

In another embodiment of the present invention, an electronic device such as a flat panel display, lighting, and backlighting including the organic electroluminescent device is provided.

Hereinafter, the electron transport material according to the present invention will be described below through representative examples. However, the method for synthesizing the electron transporting material of the present invention is not limited to the method exemplified below, and the electron transporting material of the present invention can be produced by the methods exemplified below and methods known in the art.

(Example)

An electron transport material (SMH-E-10) according to a preferred embodiment of the present invention was synthesized in which at least two styrene groups are included at the ends of the core material according to the following [Scheme].

[Reaction formula]

[Preparation of intermediate (1)]

In a 250 mL one-neck flask under a nitrogen atmosphere, 1- (4-bromophenyl) 2-phenylbenzimidazole (5 g, 0.014 mol), Bis (Pinacolato) diboron (3.6 g, 0.014 mol), potassium acetate (4.1 g, 0.042 mol) , Pd (pph ₃ ) ₄ (0.8g, 0.0007mol) was added and 1,4-dioxane (100 mL) was added and stirred. The reaction proceeds by refluxing at 110 ° C. for 24 hours. After the reaction is completed, it is cooled at room temperature and extracted with EA / distilled water to separate the organic layer. After removing the solvent of the separated organic layer under reduced pressure, column chromatography (EA: Hx = 1:20) gives the intermediate (1) of the structural formula below.

Yield: 4.3 g (78%)

¹ H NMR (DMSO, 300 MHz); δ = 7.68 (d, -CH-), 7.52 (d, -CH-), 7.43 to 7.13 (m, -CH-), 1.25 (s, -CH ₃ )

[Preparation of intermediate (2)]

The intermediate (1) (4.3 g, 0.011 mol), 9,10-dibromoanthracene (3.7 g, 0.011 mol), Pd (pph ₃ ) ₄ (0.6 g, 0.0005 mol) was added to a 200 mL two-neck flask under a nitrogen atmosphere. , THF (100mL) was added and stirred. When all the substances in the flask are dissolved, add potassium carbonate solution (2N, 100mL). The reaction was performed by refluxing at 80 ° C for 12 hours. After completion of the reaction, the mixture was cooled at room temperature and extracted with EA / distilled water to separate the organic layer. After blowing off all the solvent of the separated organic layer, it is purified by column chromatography (MC: Hx = 1: 5) to obtain the intermediate (2) of the structural formula below.

Yield: 5.5 g (95%)

¹ H NMR (DMSO, 300 MHz); δ = 7.68 (d, -CH-), 7.52 (d, -CH-), 7.48 (t, -CH-), 7.43 ~ 7.13 (m, -CH-)

[Preparation of intermediate (3)]

The intermediate (2) (5 g, 0.0095 mol), Bis (Pinacolato) diboron (2.4 g, 0.0095 mol), potassium acetate (2.7 g, 0.028 mol), Pd (pph ₃ ) purified in a 250 mL one-neck flask under nitrogen atmosphere ) ₄ (0.5g, 0.00048mol) is added and 1,4-dioxane (100mL) is added and stirred. The reaction was performed by refluxing at 110 ° C. for 24 hours. After completion of the reaction, cool at room temperature and extract with MC / distilled water to separate the organic layer. After removing the solvent of the separated organic layer under reduced pressure, column chromatography (EA: Hx = 1: 7) to obtain the intermediate (3) of the structural formula below.

Yield: 4.3 g (80%)

¹ H NMR (DMSO, 300 MHz); δ = 7.68 (d, -CH-), 7.52 (d, -CH-), 7.48 (t, -CH-), 7.43 to 7.13 (m, -CH-), 1.25 (s, -CH ₃ )

[Preparation of intermediate (4)]

The intermediate (3) (4 g, 0.0052 mol), 1,3,5-tribromobenzene (1.6 g, 0.0052 mol), Pd (pph ₃ ) ₄ (0.4 g, 0.00026 mol) was added to a 500 mL two-neck flask under a nitrogen atmosphere. Add THF (80 mL) and stir. When all the substances in the flask are dissolved, add potassium carbonate solution (2N, 80mL). The reaction was performed by refluxing at 80 ° C for 12 hours. After completion of the reaction, cool at room temperature and extract with MC / distilled water to separate the organic layer. After the solvent of all the separated organic layers is blown off, purification is performed by column chromatography (MC: Hx = 1: 4) to obtain the intermediate (4) of the following structural formula.

Yield: 1.1 g (31%)

¹ H NMR (DMSO, 300 MHz); δ = 7.68 (d, -CH-), 7.52 (d, -CH-), 7.48 (t, -CH-), 7.43 ~ 7.13 (m, -CH-)

[Preparation of the final substance (SMH-E-10)]

Intermediate (4) (3g, 0.0092mol), (4-vinylphenyl) boronic acid (1.5g, 0.018mol), Pd (pph ₃ ) ₄ (0.024g, 0.00002mol) purified in all steps under nitrogen atmosphere, Add THF (50 mL) and stir. When all the substances in the flask are dissolved, add Photassium carbonate solution (2N, 50mL) and reflux at 80 ° C for 12 hours to proceed. After completion of the reaction, the mixture was cooled at room temperature, and extracted with EA / H ₂ O to separate the organic layer. After removing the solvent of the separated organic layer under reduced pressure, column chromatography (MC: Hx = 1: 5) gives SMH-E-10 of the following structural formula as the final material.

Yield: 0.38 g (28%)

The NMR data of the SMH-E-10, which is an electron transport material according to a preferred embodiment of the present invention thus obtained, is as shown in FIG. 1.

( Experimental example  1: solvent resistance test)

The synthesized SMH-E-10 was dissolved in an organic solvent (chlorobenzene), spin-coated on a substrate, and then heat-treated in an oven at 100 ° C, 140 ° C, 160 ° C and 180 ° C for 30 minutes to crosslink the thin film. Subsequently, for the formed thin films, the UV / Vis spectrum before soaking the solvent and the formed thin films are immersed in an organic solvent (chlorobenzene) for 5 minutes, and then the UV / Vis spectrum is measured after dipping the solvent to remove the solvent and UV / before / after solvent soaking. After calculating the ratio of the Vis spectrum it is shown in Figure 2 according to the temperature change. Referring to the graph of FIG. 2, when the organic thin film made of the electron transporting material (SMH-E-10) of the present invention was heated in an oven at 100 ° C, 140 ° C, 160 ° C and 180 ° C for 30 minutes, UV before immersing the solvent There is no significant difference between the / Vis spectrum and the UV / Vis spectrum after immersion in the solvent. That is, it can be confirmed that the electron transporting material of the present invention has resistance to a solvent. It can be seen that the electron transporting material of the present invention containing at least two or more styrene functional groups at the terminal has a resistance to solvents due to crosslinking during the styrene action period at a specific temperature condition (heated at 180 ° C. or less for 30 minutes). have.

( Experimental example  2: Organic electroluminescence device performance test)

<Example>

After cleaning the ITO substrate, PEODT: PSS is spin-coated and heat-treated at 180 ° C for 30 minutes to form a 20nm thick hole injection layer (HIL). Spin coating N4, N4'-Di (naphthalen-1-yl) -N4, N4'-bis (4-vinylphenyl) biphenyl-4,4'-diamine (VNPB) on this hole injection layer (PEDOT: PSS thin film) After that, heat treatment is performed at 180 ° C for 30 minutes to form a hole transport layer (HTL) having a thickness of 20 nm. As a host material, 4,4'-Bis (3-((4-vinylphenoxy) methyl) -9H -carbazol-9-yl) biphenyl (dv-CBP) and a solution of Ir (mppy) 3 dissolved in chlorobenzene as a dopant are described above. After spin coating on the hole transport layer (HTL), heat treatment is performed at 180 ° C. for 30 minutes to form a 20 nm thick light emitting layer. The electron transporting material (SMH-E-10) synthesized above was spun coated to a thickness of 20 nm, and then heat-treated at 180 ° C. for 30 minutes to form an electron transporting layer (ETL). An organic electroluminescent device of the embodiment was completed by vacuum-depositing LiF and Al on the electron transport layer (ETL) to form an electrode.

<Comparative Example>

After cleaning the ITO substrate, PEODT: PSS is spin coated and then heat treated at 180 ° C for 30 minutes to form a hole injection layer (HIL) having a thickness of 20nm. Spin coating of N4, N4'-Di (naphthalen-1-yl) -N4, N4'-bis (4-vinylphenyl) biphenyl-4,4'-diamine (VNPB) on this hole injection layer (PEDOT: PSS thin film) After that, heat treatment is performed at 180 ° C for 30 minutes to form a hole transport layer (HTL) having a thickness of 20 nm. As a host material, 4,4'-Bis (3-((4-vinylphenoxy) methyl) -9H -carbazol-9-yl) biphenyl (dv-CBP) and a solution of Ir (mppy) 3 dissolved in chlorobenzene as a dopant are described above. After spin coating on the hole transport layer (HTL), heat treatment is performed at 180 ° C. for 30 minutes to form a 20 nm thick light emitting layer. An electron transport layer (ETL) is formed by vacuum-depositing TPBI (1,3,5-tris (N-phenylbenzimidazole-2-yl) benzene) on the light emitting layer to a thickness of 20 nm. An organic electroluminescent device of a comparative example was completed by vacuum-depositing LiF and Al on this electron transport layer (ETL) to form an electrode.

<Current-voltage characteristic test>

3A is a graph showing the current-voltage characteristics of the organic light-emitting device of the embodiment, and FIG. 3B is a graph showing the current-voltage characteristics of the organic EL device of the comparative example. Referring to FIG. 3, it can be seen that when the voltage of both the light emitting devices of the Examples and Comparative Examples increases more than a certain level, the current rapidly increases. This is an organic layer formed of an organic thin film formed of an electron transport layer SMH-E-10, which is an electron transport material by a solution process, and an organic layer formed by vacuum deposition of an electron transport material, TPBI, as an electron transport layer. It shows that all organic electroluminescent devices (comparative examples) composed of thin films are operated with equal efficiency.

<Current efficiency test>

Figure 4a is a graph showing the current efficiency according to the change in the current density of the organic light emitting device of the embodiment, Figure 4b is a graph showing the current efficiency according to the change in the current density of the organic light emitting device of the comparative example. In general, it is known that a device fabricated by a deposition process exhibits significantly higher efficiency than a device fabricated by a solution process. However, referring to FIG. 4, the current efficiency of the organic light emitting device according to the embodiment of the present invention represents a maximum value at about 35 cd / A, and the current efficiency of the organic light emitting device of the comparative example is about 36 cd / A. Indicates the maximum value. From this, it can be confirmed that the device of the embodiment of the present invention in which SMH-E-10 was applied to the electron transport layer exhibits the same current efficiency as the device of the comparative example using a deposition material. That is, it is confirmed that the SMH-E-10 of the present invention, which is an electron transport material, is efficiently operated in the organic electroluminescent device.

Claims (19)

As an electron transport material for forming an electron transport layer (ETL) disposed between the first electrode and the second electrode of the organic electroluminescent device,
The electron transport material is an electron transport material characterized in that it comprises at least two styrene groups (styrene functional group) at its ends. According to claim 1,
The electron transport material, characterized in that the electron transport material has the following formula.

As an ink composition for forming an electron transport layer (ETL) disposed between the first electrode and the second electrode of the organic electroluminescent device,
The ink composition comprises an electron transporting material containing at least two styrene functional groups at its ends. The method of claim 3,
The ink composition, characterized in that the electron transport material has the following formula.

The method of claim 3,
The ink composition is an ink composition, characterized in that the solution or suspension further comprising a solvent. The method of claim 3,
The ink composition further comprises a pigment or dye. In the organic electroluminescent device comprising a plurality of organic thin film layer comprising at least a light emitting layer and an electron transport layer (ETL) between the cathode and the anode,
An organic electroluminescent device characterized in that the electron transport material for forming the electron transport layer (ETL) includes at least two styrene functional groups at its ends. The method of claim 7,
An organic electroluminescent device, characterized in that cross-linking is formed between styrene functional groups at the ends of the electron transport material forming the electron transport layer (ETL). The method of claim 8,
An organic electroluminescent device characterized in that the electron transport material has the following formula.

The method of claim 8,
The organic thin film layer further includes at least one selected from the group consisting of a hole injection layer, a hole transport layer, an electron injection layer, an electron blocking layer and a hole blocking layer. The method of claim 10,
An organic electroluminescent device characterized in that the anode, the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer, the electron injection layer and the cathode have a structure stacked in this order. The method of claim 10,
The organic thin film layer is an organic electroluminescent device characterized in that the ink composition containing the organic compound is prepared by coating and drying by a solution process to form a film. An electronic device comprising the organic electroluminescent device according to claim 7. As a method of forming an electron transport layer (ETL) using an electron transport material containing at least two styrene functional groups (styrene functional group) at its end,
(1) preparing a solution by dissolving the electron transport material in a solvent;
(2) preparing a substrate including a plurality of organic thin film layers on which at least an electrode and a light emitting layer are formed;
(3) applying the solution of step (1) on the substrate;
(4) Forming an electron transport layer (ETL), characterized by comprising heat-treating the substrate coated with the solution for a predetermined period of time to form an organic thin film layer by forming crosslinking between styrene functional groups. Way. The method of claim 14,
The method of forming the electron transport layer (ETL), characterized in that the heat treatment temperature is 180 ℃. The method of claim 14,
The step (3) is spin coating, gravure offset printing, reverse offset printing, screen printing, roll-to-roll printing, slot die coating, immersion coating, spray coating, doctor blade coating, any one method selected from the group consisting of inkjet coating Method of forming an electron transport layer (ETL), characterized in that consisting of. In the method of manufacturing an organic electroluminescent device,
(1) preparing a substrate;
(2) forming an anode on top of the substrate;
(3) forming a hole injection layer on the anode;
(4) forming a hole transport layer on top of the hole injection layer;
(5) forming a light emitting layer on top of the hole transport layer;
(6) forming an electron transport layer on the light emitting layer;
(7) forming a cathode on top of the electron transport layer;
The method for manufacturing an organic electroluminescent device, characterized in that the electron transport layer of the step (6) is formed using the method of any one of claims 14 to 16. The method of claim 17,
The method of manufacturing an organic light emitting device further comprising the step of forming a hole blocking layer between the step (5) and the step (6). The method of claim 17,
A method of manufacturing an organic electroluminescent device further comprising the step of forming an electron injection layer between steps (6) and (7).

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