KR100811058B1 - A highly polymerized compound for emitting light and organic electroluminecent diode using that compound - Google Patents

Abstract

The present invention relates to a high-efficiency organic light emitting polymer compound, and more particularly, triphenylamine as a main chain, to which a fluorene and phenylenevinylene repeating unit or a substituent which facilitates the injection of electrons is introduced. The present invention relates to a light emitting polymer compound capable of manufacturing an organic light emitting device and an organic light emitting device using the same.

Light Emitting Diode, Organic Light Emitting Diode, Light Emitting Layer, Light Emitting Polymer Compound

Description

A light emitting polymer compound and an organic light emitting device using the same {A HIGHLY POLYMERIZED COMPOUND FOR EMITTING LIGHT AND ORGANIC ELECTROLUMINECENT DIODE USING THAT COMPOUND}

1 is a schematic view illustrating a structure of an organic light emitting diode according to an embodiment of the present invention.

2 is a graph comparing the luminous efficiency of Comparative Example 1 with an organic light emitting diode according to a second exemplary embodiment of the present invention.

3 is a graph comparing the luminous efficiency of the organic light emitting device according to the third embodiment of the present invention and Comparative Example 2.

The present invention relates to a high-efficiency organic light emitting polymer compound, and more particularly, triphenylamine as a main chain, to which a fluorene and phenylenevinylene repeating unit or a substituent which facilitates the injection of electrons is introduced. The present invention relates to a light emitting polymer compound and an organic light emitting device capable of manufacturing an organic light emitting device.

Recently, as the society has rapidly changed into an information society, the flat panel display is growing rapidly. In other words, while playing a very important role as a device supporting a highly advanced video information society based on the Internet, the demand and role are exploding. In particular, among the flat panel display devices, an organic light emitting device (organic EL device) capable of low voltage driving with a self-luminous type has better viewing angle, contrast ratio, etc. than a liquid crystal display (LCD), which is a mainstream of flat panel display devices, and requires no backlight. As a result, it is possible to be light and thin and has advantages in terms of power consumption. Organic electroluminescent devices are attracting attention as next-generation flat panel display devices because they have a fast response speed and are all solid, resistant to external shocks, have a wide usable temperature range, and have low manufacturing costs.

In general, light emitting diodes are classified into inorganic light emitting diodes and organic light emitting diodes. In the case of the inorganic light emitting diode, the driving voltage is 200V or more, and it has a problem that the price is expensive as well as the size of the diode. On the other hand, the organic light emitting diode has the advantages of low driving voltage and low price compared to the inorganic light emitting diode, and also has the advantage of easy multicolor due to various organic compounds.

Since the organic light emitting diode was first discovered in anthracene single crystal by Pope et al. In 1963, in 1987, Eastman Kodak announced a multi-layered organic light emitting diode emitting green light using Alq ₃ composed of conjugated double bonds by Tang et al. It became. The organic light emitting diode had a quantum efficiency of 1% luminance of 1000 cd / mm ² at 10 V or less. Since then, the company has focused on the development of organic light-emitting diodes with easy color tuning and high quantum efficiency.However, the mechanical properties are lowered compared to the light-emitting diodes developed in the past. As a result, problems of low luminous efficiency and short diode lifetime have emerged. In 1990, the University of Cambridge, England developed an electroluminescent diode using PPV having conjugated double bonds that solved the above-mentioned disadvantages of the organic light emitting diode to some extent, and developed various materials for realizing full color using organic polymer compounds. To increase the luminous efficiency, research is being actively conducted.

In the organic electroluminescent polymer compound, it is known that the driving voltage governs the driving voltage, and the electron governing the luminous efficiency is electron. The inflow of holes in the light emitting polymer compound is easy while the inflow of electrons is difficult. The introduced electrons and holes meet in the polymer to form an exciton, and when the exciton is deactivated, light of a wavelength corresponding to the band gap of the light emitting material is emitted. It is a principle. That is, the maximum luminous efficiency can be exhibited when the amount of introduced holes and the amount of electrons are in balance with each other.

The most representative method of improving the luminous efficiency of an organic electroluminescent material is the energy barrier that electrons must pass through using a cathode having a small work function or a polymer having a high electron affinity. There is a way to reduce the height.

The method of increasing the electron affinity of the polymer material is to introduce functional groups such as cyano and oxadiazole, which have strong electron affinity, into the conjugated polymer chain to lower the LUMO level to facilitate the injection of electrons.

However, the light emitting device having such a structure has a disadvantage of high driving voltage, and thus efforts have been made to increase luminous efficiency by mixing different light emitting materials. However, even in this case, there is a disadvantage in that the life of the device is shortened by rearrangement or phase separation of materials mixed with generation of space charge.

An object of the present invention is a polymer compound having high luminous efficiency by introducing a triphenylamine having a hole injection capability into a main chain, and introducing a fluorene and phenylene vinylene repeating unit or a substituent which facilitates injection of electrons, and using the same An organic electroluminescent device having excellent luminous efficiency is provided.

The organic light emitting polymer compound according to the present invention is characterized by a polymer compound represented by the following Chemical Formulas (1) and (2).

<Formula 1>

Here, R and R 'may be the same or different functional groups, and may be an alkyl, alkoxy, silyl, nitro group and the like. Ar is an arylene group.

In particular, Ar is preferably

or

이다.

to be.

In this case, R ₁ and R ₂ is hydrogen or any one selected from linear or branched alkyl group having 1 to 20 carbon atoms, alkoxy group or silyl group. And R ₃ and R ₄ are any one selected from linear or branched alkyl, alkoxy or silyl groups having 1 to 20 carbon atoms.

N is an integer ranging from 2 to 200.

<Formula 2>

Wherein R and R 'may be the same or different functional groups, and may be any of alkyl, alkoxy, silyl, nitro groups and E is cyanide, florin, iodine, oxadiazole, bromine, methoxy , Ethoxy, carbazole. Ar is an arylene group.

In particular, Ar is preferably

또는

or

이다.

to be.

In this case, R ₁ and R ₂ is hydrogen or any one selected from linear or branched alkyl group having 1 to 20 carbon atoms, alkoxy group or silyl group. And R ₃ and R ₄ are any one selected from linear or branched alkyl, alkoxy or silyl groups having 1 to 20 carbon atoms.

N is an integer ranging from 2 to 200.

Hereinafter, an organic light emitting diode manufactured using the polymer compound according to the present invention will be described with reference to FIG. 1.

1 is a schematic view showing the structure of an organic light emitting device.

As shown in FIG. 1, the organic light emitting device according to the present invention includes a transparent substrate 1, an anode electrode 2, a hole transport layer 3, a light emitting layer 4, a hole confinement layer 5, and an electron transport layer. (6) and the cathode electrode (7). The hole confinement layer 5 and the electron transport layer 6 can be omitted here.

In the present invention, as the transparent substrate 1, not only a glass plate generally used but also a film of plastic material which can be bent or bent can be used. In addition, the anode electrode 2 is manufactured by forming an indium tin oxide thin film on the transparent substrate 1 by using a method such as evaporation or sputtering.

Next, as the light emitting layer 4, a triphenylamine according to the present invention may be used as a main chain, and a high molecular compound in which fluorene, phenylene vinylene and cyano groups are introduced as repeating units may be used. The method of forming the hole transport layer 3 and the light emitting layer 4 is as follows. First, in order to apply the hole transport layer 3 and the light emitting layer 4 on the anode electrode 2, the transparent substrate 1 on which the anode electrode 2 is formed is sequentially contained an aqueous solution containing a cleaning agent, methanol, acetone, and isopropyl. The surface is cleaned by ultrasonic cleaning (ultrasonication) in an organic solvent of alcohol and then dried. Then, the hole transport material is applied on the cleaned anode electrode 2 at a rotational speed of 500 rpm to 2500 rpm to form the hole transport layer 3 in a thickness of 300 kPa to 1000 kPa. Thereafter, the polymer compound provided in the present invention is applied at a rotational speed of 500 rpm to 2500 rpm to form the light emitting layer 4 to a thickness of 300 kPa to 1000 kPa.

After the application of the polymer compound, the internal pressure is transferred to a vacuum evaporator having a high vacuum of 10 ⁻⁵ torr or less to deposit the hole thin layer 5 on the light emitting layer 4 in a thickness of 20 kPa to 200 kPa. The electron transport layer 6 is then deposited to a thickness of 100 kPa to 500 kPa. Thereafter, a mixed layer of lithium (Li) and aluminum (Al) is deposited to a thickness of 1000 kPa to 3000 kPa to form the cathode electrode 7.

Hereinafter, the present invention will be specifically described by way of examples. However, the following examples are merely illustrative of the present invention and do not limit the scope of the present invention.

Example 1 Synthesis of Light Emitting Polymer Compound

In this embodiment, a synthesis example of a specific light emitting polymer compound will be described using a reaction scheme.

1. Synthesis of Light Emitting Polymer Compound (Formula 1) example

3 (phenyl-bis- {4- [2 (4-vinyl-phenyl) -vinyl] -phenyl} -amine (M-1) and 1,4-dibromo-2,5-bis-dodecaosi in DMF After mixing benzene, a small amount of palladium acetate, tri (o-tosyl) phosphine and triethylamine were added and the resultant was heated to 100 to 200 ° C. A polymer compound was obtained by soxhlet extraction with methanol.

2. Synthesis Example of Light Emitting Polymer Compound (Formula 2)

3- [4-({4- [2-cyano-2- (4-vinyl-phenyl) -vinyl] -phenyl} -phenyl-amino) phenyl] -2- (4-vinyl-phenyl)- After acylonitrile (M-2) and 1,4-dibromo-2,5-bis-dodecaoxy-benzene were mixed, a small amount of palladium acetate, tri (o-tosyl) phosphine and triethylamine were added. The resultant reacted by addition is heated to 100-200 degreeC. The polymer compound is obtained by soxhlet extraction with methanol.

Example 2 Fabrication of Organic Electroluminescent Device 1

The transparent substrate 1 on which the anode electrode 2 is formed is sequentially cleaned by ultrasonic cleaning in an aqueous solution containing a cleaning agent and an organic solvent of methanol, acetone, and isopropyl alcohol, followed by drying.

이며, A hole transport material (PEDOT, poly (3,4-ethylenedioxythiophene)) was applied at 2000 rpm on the cleaned anode electrode 2 to form a hole transport layer 3 with a thickness of 600 kPa, followed by R And R 'are alkyl and alkoxy, respectively, and Ar

Is,

R ₁ and R ₂ each have 8 or 12 carbon atoms, and a polymer compound having n of 20 is applied at a rotational speed of 1500 rpm to form the light emitting layer 4 at a thickness of 800 kPa.

The transparent substrate 1 was transferred to a vacuum evaporator having a high vacuum of <10 ^-6 torr inside, and the hole-fast thin layer 5 (BCP, (2,9-dimethyl-4,7-diphenyl-) was formed on the light emitting layer 4. 1,10-phenanthrol)) is deposited to a thickness of 50 μs. Then, the electron transport layer 6 (Alq3, tris (8-hydroxyquinoline) aluminum) was deposited to a thickness of 150 GPa, and a mixed layer of lithium (Li) and aluminum (Al) was deposited to a thickness of 2000 GPa to form the cathode electrode 7. To form.

The organic light emitting device according to the present embodiment thus produced exhibits 125 cd / m 2 of light emission when a 10 V forward electric field is applied, and 230 cd / m 2 of light emission when a forward electric field of 11 V is applied.

Example 3 Fabrication of Organic Electroluminescent Device 2

The transparent substrate 1 on which the anode electrode 2 is formed is sequentially cleaned by ultrasonic cleaning in an aqueous solution containing a cleaning agent and an organic solvent of methanol, acetone, and isopropyl alcohol, followed by drying.

이며, A hole transport material (PEDOT, poly (3,4-ethylenedioxythiophene)) was applied at 2000 rpm on the cleaned anode electrode 2 to form a hole transport layer 3 with a thickness of 600 kPa, followed by R And R 'are alkyl and alkoxy, respectively, and Ar

Is,

R ₁ and R ₂ each have 8 or 12 carbon atoms, and a polymer compound having n of 20 is applied at a rotational speed of 1500 rpm to form the light emitting layer 4 at a thickness of 800 kPa.

The transparent substrate 1 was transferred to a vacuum evaporator having a high vacuum of <10 ^-6 torr inside, and the hole-fast thin layer 5 (BCP, (2,9-dimethyl-4,7-diphenyl-) was formed on the light emitting layer 4. 1,10-phenanthrol)) is deposited to a thickness of 50 μs. Then, the electron transport layer 6 (Alq3, tris (8-hydroxyquinoline) aluminum) was deposited to a thickness of 150 GPa, and a mixed layer of lithium (Li) and aluminum (Al) was deposited to a thickness of 2000 GPa to form the cathode electrode 7. To form.

The organic light emitting diode according to the present exemplary embodiment thus exhibits light emission of 132 cd / m 2 when an 8 V forward electric field is applied, and light emission of 265 cd / m 2 when a forward electric field of 10 V is applied.

<Comparative Example 1>

The transparent substrate 1 on which the anode electrode 2 is formed is sequentially cleaned by ultrasonic cleaning in an aqueous solution containing a cleaning agent and an organic solvent of methanol, acetone, and isopropyl alcohol, followed by drying.

A hole transport material (PEDOT, poly (3,4-ethylenedioxythiophene)) was applied at 2000 rpm on the cleaned anode electrode 2 to form a hole transport layer 3 having a thickness of 600 kPa. And a high molecular compound (Polyfluorene series) is applied at a rotational speed of 1500rpm to form a light emitting layer 4 to a thickness of 800Å.

The transparent substrate 1 was transferred to a vacuum evaporator having a high vacuum of <10 ^-6 torr inside, and the hole-fast thin layer 5 (BCP, (2,9-dimethyl-4,7-diphenyl-) was formed on the light emitting layer 3. 1,10-phenanthrol)) is deposited to a thickness of 50 μs. Then, the electron transport layer 6 (Alq3, tris (8-hydroxyquinoline) aluminum) was deposited to a thickness of 150 GPa, and a mixed layer of lithium (Li) and aluminum (Al) was deposited to a thickness of 2000 GPa to form the cathode electrode 7. To form.

The organic light emitting device manufactured as described above exhibits light emission of 110 cd / m 2 when a forward electric field of 10 V is applied, and light emission of 210 cd / m 2 when a forward electric field of 11 V is applied.

<Comparative Example 2>

The transparent substrate 1 on which the anode electrode 2 is formed is sequentially cleaned by ultrasonic cleaning in an aqueous solution containing a cleaning agent and an organic solvent of methanol, acetone, and isopropyl alcohol, followed by drying.

A hole transport material (PEDOT, poly (3,4-ethylenedioxythiophene)) was applied at 2000 rpm on the cleaned anode electrode 2 to form a hole transport layer 3 having a thickness of 600 kPa. And a high molecular compound (polyphenylenevinylene series) is applied at a rotational speed of 1500rpm to form a light emitting layer 4 to a thickness of 800Å.

The transparent substrate 1 was transferred to a vacuum evaporator having a high vacuum of <10 ^-6 torr inside, and the hole-fast thin layer 5 (BCP, (2,9-dimethyl-4,7-diphenyl-) was formed on the light emitting layer 3. 1,10-phenanthrol)) is deposited to a thickness of 50 μs. Then, the electron transport layer 6 (Alq3, tris (8-hydroxyquinoline) aluminum) was deposited to a thickness of 150 GPa, and a mixed layer of lithium (Li) and aluminum (Al) was deposited to a thickness of 2000 GPa to form the cathode electrode 7. To form.

The organic light emitting device manufactured as described above exhibits light emission of 109 cd / m 2 when an 8 V forward electric field is applied, and light emission of 216 cd / m 2 when a 10 V forward electric field is applied.

2 is a graph comparing the light emission efficiency of the organic light emitting device manufactured by Example 2 and Comparative Example 1, Figure 3 is a light emission efficiency of the organic light emitting device manufactured by Example 3 and Comparative Example 2 This is a graph comparing.

When the organic light emitting device is manufactured using the polymer compound according to the present invention, it is easy to inject electrons, thereby lowering the operating voltage and increasing the luminous efficiency, thereby providing an organic light emitting device having high efficiency.

Claims (12)

A light emitting polymer compound represented by the following formula (1). <Formula 1>

Wherein R and R 'may be the same or different functional groups and are selected from the group consisting of alkyl, alkoxy, silyl, nitro groups, Ar is an arylene group, n is an integer within 2 to 200. The method of claim 1, wherein Ar is

or

A light emitting polymer compound, characterized in that any one selected from. (Wherein R ₁ and R ₂ are selected from the group consisting of hydrogen or linear or branched alkyl group having 1 to 20 carbon atoms, alkoxy group or silyl group, R ₃ and R ₄ are linear having 1 to 20 carbon atoms) Or a branched alkyl group, alkoxy group or silyl group.) A light emitting polymer compound represented by the following formula (2). <Formula 2>

In the above, R and R 'may be the same or different functional groups, it may be any one of alkyl, alkoxy, silyl, nitro group. E can be selected from any one of cyanide, florin, iodine, oxadiazole, bromine, methoxy, ethoxy, carbazole. Ar is an arylene group. And n is an integer within 2 to 200. The method of claim 3, wherein Ar is

or

A light emitting polymer compound, characterized in that any one selected from. (Wherein R ₁ and R ₂ are selected from the group consisting of hydrogen or linear or branched alkyl group having 1 to 20 carbon atoms, alkoxy group or silyl group, R ₃ and R ₄ are linear having 1 to 20 carbon atoms) Or a branched alkyl group, alkoxy group or silyl group.) An organic electroluminescent device comprising a polymer light emitting layer formed of the light emitting polymer compound according to claim 1. The method of claim 5, wherein the organic light emitting device, An organic electroluminescent device, comprising: an organic electroluminescent device formed by sequentially stacking an anode electrode, a hole transport layer, a polymer light emitting layer, and a cathode electrode on a substrate. The method of claim 5, wherein the organic light emitting device, An organic electroluminescent device comprising a multilayer thin film structure in which an anode electrode, a hole transport layer, a polymer light emitting layer, an electron transport layer, and a cathode electrode are sequentially formed on a substrate. An organic electroluminescent device comprising a polymer light emitting layer formed of the light emitting polymer compound according to claim 3. The method of claim 8, wherein the organic light emitting device, An organic electroluminescent device, comprising: an organic electroluminescent device formed by sequentially stacking an anode electrode, a hole transport layer, a polymer light emitting layer, and a cathode electrode on a substrate. The method of claim 8, wherein the organic light emitting device, An organic electroluminescent device comprising a multilayer thin film structure in which an anode electrode, a hole transport layer, a polymer light emitting layer, an electron transport layer, and a cathode electrode are sequentially formed on a substrate. delete delete

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