KR102155063B1 - Organic light emitting complex and organic light emitting device comprising the same - Google Patents

Abstract

The present invention provides an organic light-emitting composite in which light emission efficiency is remarkably improved by forming a composite of a specific organic light-emitting compound and a hydrogen-bonding polymer compound, and an organic light-emitting device including the same.

Description

Organic light emitting complex and organic light emitting device comprising the same

The present invention relates to an organic light-emitting composite and an organic light-emitting device including the same, and more specifically, to an organic light-emitting composite in which light emission efficiency is remarkably improved by forming a composite of a specific organic light-emitting compound and a hydrogen bonding polymer compound. .

In general, the organic light emission phenomenon refers to a phenomenon in which electrical energy is converted into light energy using an organic material. An organic light-emitting device using the organic light-emitting phenomenon has a wide viewing angle, excellent contrast, and fast response time, and has excellent luminance, driving voltage, and response speed characteristics, and thus many studies are being conducted.

The organic light emitting device generally has a structure including an anode and a cathode, and an organic material layer between the anode and the cathode. The organic material layer is often made of a multi-layered structure made of different materials in order to increase the efficiency and stability of the organic light-emitting device.For example, it may be formed of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and the like. In the structure of such an organic light-emitting device, when a voltage is applied between the two electrodes, holes are injected from the anode and electrons from the cathode are injected into the organic material layer, and excitons are formed when the injected holes and electrons meet. It glows when it falls back to the ground.

On the other hand, each layer constituting the organic light emitting device is mostly formed by evaporation in a vacuum. In the case of manufacturing the device through the vacuum evaporation method, it is difficult to make a large area due to the nature of the process and requires expensive evaporation equipment to reduce the manufacturing cost. There was a problem that was difficult to do.

In order to solve this problem, research has been actively conducted on an organic light emitting device through a solution process. Since the organic device material used in the existing deposition method has a low solubility in a solvent, the solution process is usually made by applying a solution consisting of a polymer organic material and a solvent to cure it, so that the solution does not dissolve the lower layer. It is necessary to select an appropriate solvent, and in some cases, there is a hassle in the process requiring a separate insolubilization treatment.

In addition, while the polymer material is capable of a solution process and has excellent thin film formation characteristics, it is difficult to fabricate a high-purity organic light-emitting device due to molecular weight distribution, and has a disadvantage in that its performance is lower than that of an organic light-emitting device using a low molecular weight compound.

As described above, the development of new materials that do not degrade the performance of the organic light-emitting device even when used in the solution process is continuously required.

Korean Patent Publication No. 10-2008-0062807

The present invention relates to an organic light emitting composite and an organic light emitting device including the same.

The present invention provides an organic light-emitting composite comprising a compound represented by the following Formula 1 and a polymer compound having a hydrogen bonding moiety.

An organic light-emitting composite comprising a compound represented by the following Formula 1 and a polymer compound having a hydrogen bonding moiety.

[Formula 1]

In Formula 1,

R ₁ and R ₁ ′ are each independently hydrogen, deuterium or methyl,

R ₂ and R ₂ ′ are each independently C, O, S or Si,

n1 and n2 are each independently an integer of 0 to 10.

In addition, the present invention is a first electrode; A second electrode provided to face the first electrode; And one or more organic material layers provided between the first electrode and the second electrode, wherein at least one of the organic material layers includes the organic light-emitting composite of the present invention. .

The organic light-emitting composite according to the present invention can be used as a material for an organic material layer of an organic light-emitting device, and in particular, it can be used as a material for a light-emitting layer to remarkably improve luminous efficiency.

In addition, when an organic light-emitting device including the organic light-emitting composite according to the present invention is manufactured by a solution process, a multilayer thin film having a stable structure can be formed without dissolving adjacent layers by the solution.

1 is H-NMR data of compound 1 represented by Chemical Formula 1 synthesized in Preparation Example 1. FIG.
2 shows emission images of Example 1 and Comparative Example 1.

The organic light-emitting composite according to an embodiment of the present invention includes a compound represented by Formula 1 and a polymer compound having a hydrogen bonding moiety.

In the case of conventional organic light emitting materials, there is a problem in that the luminous efficiency is significantly lowered due to a self-quenching phenomenon in which energy is lost due to an interaction between molecules and returns to a ground state without emitting light. However, the organic light-emitting composite according to the present invention is in the form of a composite containing an organic light-emitting compound having excellent luminous efficiency and a specific polymer, and suppresses vibrational loss of excited electrons of the organic light-emitting compound with a specific substitution structure of the polymer. Was able to emit light efficiently. In addition, self-quenching was effectively controlled by maintaining an appropriate distance between organic light-emitting compounds by the specific polymer of the present application.

Hereinafter, this will be described in more detail.

Ⅰ. Organic light emitting complex

The organic light-emitting composite according to an embodiment of the present invention is a form in which an organic light-emitting compound is hydrogen-bonded in a polymer paper body, and includes a compound represented by the following formula (1) as an organic light-emitting compound:

[Formula 1]

In Formula 1,

R ₁ and R ₁ ′ are each independently hydrogen, deuterium or methyl,

R ₂ and R ₂ ′ are each independently C, O, S or Si,

n1 and n2 are each independently an integer of 0 to 10.

The aldehyde structure of Formula 1 is combined with a hydrogen bonding moiety of a polymer to be described later to suppress vibrational loss of excited electrons, thereby enabling electrons to emit light efficiently. In addition, since the aromatic structure of Formula 1 is positioned between the polymer chains to maintain an appropriate distance from each other, thereby preventing self-quenching due to aggregation, quantum efficiency can be improved.

Preferably, the compound represented by Formula 1 may be a compound represented by Formula 1-1 below.

[Formula 1-1]

.

.

The organic light-emitting composite according to an embodiment of the present invention includes a polymer compound having a hydrogen bonding moiety together with the compound represented by Formula 1, wherein the organic light-emitting compound is hydrogen-bonded in the polymer matrix, and the hydrogen bonding is performed. By suppressing vibrational loss, electrons can emit light efficiently. In particular, as the distance between the organic light-emitting bodies is appropriately reduced by the polymer matrix, the effect of self-quenching is reduced, thereby remarkably increasing quantum efficiency.

The hydrogen bonding moiety may be at least one selected from the group consisting of -NH, -C=O, and -OH.

The polymer compound having the hydrogen bonding moiety is polyacrylic acid, poly vinyl alcohol, polymaleic acid, polyglutamic acid, and polyacrylamide. It may be at least one selected from the group consisting of, more preferably polyacrylic acid (Polyacrylic acid), may be polyvinyl alcohol (Poly vinyl alcohol).

The weight average molecular weight (GPC) of the polymer compound having a hydrogen bonding moiety may be 1,000 g/mol to 100,000 g/mol, more preferably 1,500 g/mol to 50,000 g/mol, or 3,000 g/mol to 10,000 may be g/mol.

In the present specification, the weight average molecular weight refers to the weight average molecular weight in terms of polystyrene measured by the GPC method. In the process of measuring the weight average molecular weight in terms of polystyrene measured by the GPC method, a commonly known analysis device, a detector such as a Refractive Index Detector, and a column for analysis can be used. Conditions, solvents, and flow rates can be applied.

In an embodiment of the present invention, the compound represented by Formula 1 may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polymer compound having a hydrogen bonding moiety. More preferably, it may be included in 2 to 5 parts by weight. It is mixed in the above content range to realize the excellent luminous efficiency for the purpose of the present invention.

On the other hand, when the compound represented by Formula 1 is contained in an amount of less than 1 part by weight, it is difficult to achieve the desired luminous efficiency by being applied to an organic light-emitting device in a small amount. Due to self-quenching, the luminous efficiency is significantly reduced.

Ⅱ. Coating composition

The organic light-emitting composite according to the present invention may form an organic material layer, particularly a light-emitting layer, of an organic light-emitting device. To this end, the present invention provides a coating composition comprising the organic light-emitting composite and a solvent according to the present invention described above.

The solvent is not particularly limited as long as it is a solvent capable of dissolving or dispersing the compound represented by Formula 1 according to the present invention and a polymer having a hydrogen bonding moiety, and examples thereof include chloroform, methylene chloride, 1,2-dichloroethane, Chlorine solvents such as 1,1,2-trichloroethane, chlorobenzene, and o-dichlorobenzene; Ether solvents such as tetrahydrofuran and dioxane; Aromatic hydrocarbon solvents such as toluene, xylene, trimethylbenzene, and mesitylene; Aliphatic hydrocarbon solvents such as cyclohexane, methylcyclohexane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; Ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone; Ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate; Polyvalents such as ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, dimethoxyethane, propylene glycol, diethoxymethane, triethylene glycol monoethyl ether, glycerin, 1,2-hexanediol, etc. Alcohol and its derivatives; Alcohol solvents, such as methanol, ethanol, propanol, isopropanol, and cyclohexanol, etc. are mentioned. In addition, the above-described solvent may be used alone or in combination of two or more solvents. Preferably, tetrahydrofuran may be used.

The present invention provides a method of forming an organic material layer by using the coating composition.

A method of manufacturing an organic material layer according to an embodiment of the present invention includes applying the above-described coating composition to an upper portion of a substrate, and performing heat treatment or light treatment on the substrate to which the coating composition is applied for a predetermined time.

The method of applying the solution is any one 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, and inkjet coating. It can be done in a way.

In addition, in the heat treatment step, the heat treatment temperature is preferably performed at a temperature of 70 to 170° C., and argon or nitrogen is preferably performed in an inert gas atmosphere.

Ⅲ. Organic light emitting element

In addition, the present invention provides an organic light-emitting device including the organic light-emitting composite according to the present invention. Specifically, the present invention provides a first electrode; A second electrode provided to face the first electrode; And at least one organic material layer provided between the first electrode and the second electrode, and at least one of the organic material layers includes the organic light emitting composite according to the present invention.

Preferably, the organic light-emitting composite may be included in an emission layer among organic material layers.

In addition, the emission layer may emit red, green, or blue light, and preferably, green light.

The organic light-emitting device according to the present invention may be manufactured by materials and methods known in the art, except that the organic light-emitting composite according to the present invention is included in the emission layer and is manufactured as described above.

For example, the organic light-emitting device according to the present invention may be manufactured by sequentially laminating an anode, an organic material layer, and a cathode on a substrate. At this time, using a PVD (physical vapor deposition) method such as sputtering or e-beam evaporation, the anode is formed by depositing a metal or a conductive metal oxide or an alloy thereof on the substrate. And, after forming an organic material layer including a hole injection layer, a hole transport layer, a light emitting layer and an electron transport layer thereon, it can be prepared by depositing a material that can be used as a cathode thereon.

In addition to this method, an organic light-emitting device may be manufactured by sequentially depositing an organic material layer and an anode material from a cathode material on a substrate. However, the manufacturing method is not limited thereto.

As the anode material, a material having a large work function is preferable so that holes can be smoothly injected into the organic material layer. Specific examples of the cathode material include metals such as vanadium, chromium, copper, zinc, and gold, or alloys thereof; Metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); A combination of a metal and an oxide such as ZnO:Al or SNO ₂ :Sb; Poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene] (PEDOT), conductive polymers such as polypyrrole and polyaniline, and the like, but are not limited thereto.

It is preferable that the cathode material is a material having a small work function to facilitate electron injection into the organic material layer. Specific examples of the negative electrode material include metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead, or alloys thereof; There are multi-layered materials such as LiF/Al or LiO ₂ /Al, but are not limited thereto.

The hole injection layer (HIL) is formed of a compound that facilitates hole injection by lowering the injection energy barrier of holes injected from the anode, and specific examples of the hole injection layer include 4,4', 4"-Tris(N,N-diphenyl-amino)triphenylamine (NATA), 4,4',4"-Tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA) and poly(3,4 -Ethylenedioxythiophene):poly(styrenesulphonic acid) (PEDOT:PSS), and the like, and any known material for a hole injection layer may be used without limitation.

Next, the hole transport layer (HTL) serves to transport the holes injected from the anode to the light emitting layer without loss, and a specific example of the hole transport layer is TCTA (Tris (4-carbazoyl-9-ylphenyl)). )amine), TAPC (4,4'-Cyclohexylidenebis[N,N-di(p-tolyl)aniline]), 3,3'-bis[di(p-tolyl)amino]biphenyl, etc. Any material for the hole receiving layer can be used without limitation.

The emitting material layer (EML) is a layer that emits light through recombination of holes injected from the anode and electrons injected from the cathode, and may emit red, blue, and green light depending on the binding energy in the emission layer. , A white light-emitting layer may be formed by configuring a plurality of light-emitting layers. The light-emitting layer is the organic light-emitting composite according to the present invention, and preferably emits green light.

The hole blocking layer (HBL) plays a role of suppressing the movement of holes that cannot be combined with electrons in the emission layer, and specific examples of the hole blocking layer include Balq, 2,2',2"-( 1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)(TPBi), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), etc. , Any known material for a hole blocking layer may be used without limitation.

The electron transport layer (ETL) performs a role of transporting electrons injected from the cathode to the emission layer, thereby improving the binding probability of holes and electrons in the emission layer. In order to perform this role, it is preferable to use a material having excellent electron affinity and good interfacial adhesion with the cathode. Specific examples of the electron transport layer include Alq3 (Tris(8-hydroxy-quinolinato)aluminium), Balq(Bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminium), BeBq2(Bis(10-hydroxybenzo[ h]quinolinato)beryllium), etc., and any known material for an electron transport layer may be used without limitation.

The electron injection layer (EIL) plays a role of facilitating injection of electrons from the cathode by lowering the potential barrier during electron injection, and specific examples of the electron injection layer include LiF, 8-Hydroxyquinolinolato-lithium (Liq), 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene(TmPyPB), and the like, and any known material for an electron injection layer may be used without limitation.

The organic light-emitting device according to an embodiment of the present invention may be a top emission type, a bottom emission type, or a double-sided emission type depending on the material used.

In addition, the organic light-emitting composite according to an embodiment of the present invention may be included in an organic solar cell or an organic transistor in addition to the organic light-emitting device.

Hereinafter, the manufacturing of the organic light-emitting composite and the organic light-emitting device including the same will be described in detail. However, the following examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

Manufacturing example 1: Synthesis of luminous compound 1

According to Scheme 1, compound 1 (BHTA, 2,5-bis(hexyloxy)terephthalaldehyde) was synthesized.

[Scheme 1]

2,5-dibromohydroquinone (1eq.) and 1-boromohexane (2eq.) were added to the glass flask, and an excess of DMF solution was added. K ₂ CO ₃ (3eq) was added to the mixed solvent and stirred at about 75° C. for about 10 hours.

The reaction product was cooled to room temperature, and then intermediate compound A was confirmed using column chromatography.

Thereafter, an excess amount of THF was added to the intermediate compound A (1 eq.) to the glass flask, and n-buthylithium (1 eq.) was added to the glass flask, which was put in a dry ice bath and cooled to about -78°C while cooling to about -78°C. Stir for 1 hour. Then, DMF (Anhydrous) (4eq.) was added and stirred at 23° C. for 3 hours.

The reaction was quenched and extracted with diethyl ether to synthesize compound 1 (BHTA, 2,5-bis(hexyloxy)terephthalaldehyde). H ¹ NMR data for Compound 1 are shown in FIG. 1.

Example One

An organic light-emitting composite was prepared by dissolving 0.025 g of the compound of Preparation Example 1 (BHTA, 2,5-bis(hexyloxy) terephthalaldehyde) and 1.0 g of Poly(acrylic acid) (Sigma Aldrich, Mw=1,800) in Tetrahydrofuran (THF).

Thereafter, the composite was spin-coated on a glass substrate to prepare a film specimen.

Example 2

A film specimen was prepared in the same manner as in Example 1, except that 0.025 g of the compound of Preparation Example 1 and 1.0 g of Poly(vinyl alcohol) (Sigma Aldrich, Mw=9,000-10,000) were used as a polymer compound.

Example 3

A film specimen was prepared in the same manner as in Example 1, except that 0.025 g of the compound of Preparation Example 1 and 1.0 g of the polymer compound Polyacrylamide (Sigma Aldrich, Mn=40,000) were used.

Comparative example One

The TBP (2,5,8,11-Tetra- tert- butylperylene) compound of the following Formula B was used alone.

[Formula B]

This was deposited on a glass substrate by a sputtering method to prepare a film specimen.

Comparative example 2

Comparative Example 1 and Comparative Example 1, except that the compound of Preparation Example 1 was used alone instead of TBP of Comparative Example 1 Film specimens were prepared in the same way.

Experimental example : Quantum efficiency measurement

For the film specimens of Examples and Comparative Examples, absolute quantum efficiency was measured. Absolute quantum efficiency is a measurement of the absolute value (internal quantum efficiency) of the luminescence quantum efficiency of a material, and was measured using Otsuka Electronics manufactured by QE-1000.

As a result of the experiment, the absolute quantum efficiency of Example 1 was 13.2%, and the absolute quantum efficiency of Comparative Example 1 was 3.01%, and it was confirmed that Example 1 realized a remarkably improved luminous effect of about 4.4 times or more. In addition, it was confirmed that Example 2 was 9.4%, Example 3 was 7.2%, and Comparative Example 2 was 2.9%.

In addition, the light emission images of Example 1 and Comparative Example 1 are shown in FIG. 2, and it can be seen from a photographic image that when the organic light emitting composite according to the present invention is used, significantly improved luminous efficiency is realized.

Claims (9)

An organic light-emitting composite comprising a compound represented by the following Formula 1 and a polymer compound having a hydrogen bonding moiety.
[Formula 1]

In Formula 1,
R ₁ and R ₁ ′ are each independently hydrogen, deuterium or methyl,
R ₂ and R ₂ ′ are each independently O, S, -CH ₂ -or -SiH ₂ -,
n1 and n2 are each independently an integer of 0 to 10.
The method of claim 1,
The compound represented by Formula 1 is a compound represented by Formula 1-1 below:
[Formula 1-1]

.
The method of claim 1,
The hydrogen bonding moiety is at least one selected from the group consisting of -NH, -C=O, and -OH.
The method of claim 1,
The polymer compound having a hydrogen bonding moiety is from the group consisting of polyacrylic acid, poly vinyl alcohol, polymaleic acid, polyglutamic acid, and polyacrylamide. At least one selected, organic light-emitting composite.
The method of claim 1,
The weight average molecular weight (GPC) of the polymer compound having a hydrogen bonding moiety is 1,000 g/mol to 100,000 g/mol, an organic light-emitting composite.
The method of claim 1,
The compound represented by Formula 1 is contained in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polymer compound having a hydrogen bonding moiety.
The method of claim 1,
The compound represented by Formula 1 is contained in an amount of 2 to 5 parts by weight based on 100 parts by weight of the polymer compound having a hydrogen bonding moiety.
A first electrode; A second electrode provided to face the first electrode; And one or more organic material layers provided between the first electrode and the second electrode, wherein at least one of the organic material layers is the organic light-emitting composite according to any one of claims 1 to 7. Which, organic light-emitting device comprising a.
The method of claim 8,
The organic material layer including the organic light-emitting composite is an emission layer.

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