KR101544265B1 - Charge transfer material containing vinyl end group and Organic light emitting device using the same - Google Patents

Abstract

The present invention relates to a method for producing an organic electroluminescent device by mixing a charge transfer material having a vinyl terminal group with an organic layer between an anode and a cathode to induce a reaction between oxygen and moisture in the organic electroluminescent device, The present invention relates to an organic electroluminescent device having improved pixel shrinkage by suppressing deterioration of an organic layer, wherein the organic layer may be composed of multiple layers, and the hole injecting layer, the hole transporting layer, the light emitting layer, the electron transporting layer, Structure.

Description

[0001] The present invention relates to a charge transport material having a vinyl terminal group and an organic electroluminescent device using the same,

The present invention relates to a charge transport material having a vinyl terminal group and an organic electroluminescent device using the same. More particularly, the present invention relates to an organic electroluminescent device having improved light emission performance.

An organic electroluminescent device is a self-luminous device using a phenomenon in which electrons and holes combine in an organic layer and generate light when a current is applied to a fluorescent or phosphorescent organic film. The organic electroluminescent device is lightweight, has a simple structure and has a relatively simple structure have. Also, it is possible to realize a high image quality, a wide viewing angle can be secured, and a moving image can be completely implemented. In addition, it can realize high color purity, low power consumption, and low voltage driving, and thus has electrical characteristics suitable for portable electronic devices.

Cumpston et al., J. Appl. Phys. 81, 3716 (1997), one of the biggest factors determining the lifetime of OLED devices is the deterioration of organic matter by oxygen and moisture. Therefore, one of the key technologies for suppressing degradation of OLED devices is to protect them from oxygen and moisture. One of the main reasons why the lifetime of the organic display is not long is that oxygen or moisture in the atmosphere and organic materials constituting the display react with each other during the driving of the display to degrade the performance of the device. Therefore, it is essential to prevent the oxygen and moisture in the air from easily penetrating the organic thin film to improve the lifetime of the device. In general, OLED lifetime is reported to be short compared to the lifetime of PDP or LCD. Lifetime research has attempted to solve the problem by developing material of light emitting layer or common layer. However, sealing technology for protecting oxygen and moisture sensitive material Development. The encapsulation technique prevents the light emitting material and the electrode material from being oxidized by the oxygen and moisture introduced from the outside of the device to reduce the lifetime of the device.

The organic electroluminescent device disclosed in U.S. Patent No. 6,246,179 includes an anode, a cathode, and an emissive element layer interposed between the two electrodes. The anode is covered with an insulating film having a flat surface around the anode, and the anode exposed by the insulating film is in contact with the light emitting element layer. The encapsulation of the organic electroluminescent device has contributed to the improvement of the lifetime of the organic electroluminescent device by protecting the organic electroluminescent device from external oxygen and moisture.

However, even if the organic electroluminescent device is sealed, the lifetime characteristics of the organic electroluminescent device are seriously affected due to the limit of durability of the encapsulating material over time and the oxygen that may be introduced due to deterioration and moisture that may be present on the surface of the insulating film. Can receive. One of the fatal effects is pixel shrinkage. The phenomenon of pixel shrinkage refers to a phenomenon in which the light emitting element layer is deteriorated from the peripheral portion of the light emitting region in the driving process of the organic electroluminescence device to reduce the light emitting area.

SUMMARY OF THE INVENTION The present invention has been made to overcome the above problems, and it is an object of the present invention to provide a method of manufacturing an organic electroluminescence device, which comprises mixing a charge transport material having a vinyl terminal group with an organic layer between an anode and a cathode, The present invention relates to an organic electroluminescent device having excellent light emitting performance with improved pixel shrinkage by inducing a reaction with oxygen and water present therein to suppress deterioration of an organic layer due to oxygen and moisture, It is an object of the present invention to provide a charge transport material having a terminal group.

In order to accomplish the above object, the present invention provides, as one aspect of the present invention, a charge transfer material having a vinyl end group.

According to another aspect of the present invention, there is provided a semiconductor device comprising: an anode; Cathode; And an organic layer in which a charge transfer material having a vinyl terminal group is mixed between the anode and the cathode.

The effect of the present invention is that a charge transfer material having a vinyl terminal group is mixed with an organic layer between an anode and a cathode to perform an electrophilic addition reaction with moisture present in the organic electroluminescence device or oxidized by oxygen to form an organic layer from moisture and oxygen It is possible to obtain an organic electroluminescence device with improved lifetime characteristics by improving pixel shrinkage.

1 is a schematic cross-sectional view of an organic electroluminescent device according to an embodiment of the present invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Therefore, the present invention encompasses all changes and modifications that come within the scope of the invention as defined in the appended claims and equivalents thereof.

First, the organic EL device 100 of the present invention will be described in detail. 1 is a schematic cross-sectional view of an organic electroluminescent device 100 according to an embodiment of the present invention. As shown in FIG. 1, the organic EL device 100 of the present invention includes an organic layer 30. The organic layer 30 comprises a charge transport material having a vinyl end group. The charge transfer material having the vinyl end group is a compound represented by the following formula (1) or (2).

[Chemical Formula 1]

In the above formula (1), R is a compound having a carbon number of 1 having a cyano group.

(2)

In the above formula (2), R is a compound having a carbon number of 1 having a cyano group.

The organic layer 30 may be a single layer made of a light emitting layer 33. The organic layer 30 may be a multilayer including a light emitting layer 33. That is, at least one of the hole injecting layer 31, the hole transporting layer 32, the hole blocking layer 34, the electron transporting layer 35, and the electron injecting layer 36, including the light emitting layer 33, Or an organic layer 30 formed in a multilayer structure.

On both sides of the organic layer 30, an anode 20 and a cathode 40 are formed. The anode (20) is formed on the substrate (10). The substrate 10 may be a glass substrate 10 or a transparent plastic substrate 10 having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and waterproofness.

Next, a method of manufacturing an organic electroluminescent device 100 according to an embodiment of the present invention will be described with reference to FIG.

First, the substrate 10 is prepared. As the substrate 10, a glass substrate 10 or a transparent plastic substrate 10 having excellent mechanical strength, thermal stability, transparency or ease of handling can be used.

Next, the anode 20 may be formed on the substrate 10 by a vacuum deposition method, a sputtering method, or the like. The anode 20 may be a metal oxide of at least one of indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), and zinc oxide (ZnO), or a mixture thereof. The anode 20 may be formed of a reflective electrode or a transmissive electrode, and various modifications are possible. Then, an organic layer 30 is formed on the anode 20.

The organic layer 30 may be a single layer composed of the light emitting layer 33 or may be a multilayer of two or more layers including the light emitting layer 33. That is, the multilayer organic layer 30 includes at least one of a hole injection layer 31, a hole transport layer 32, a hole blocking layer 34, an electron transport layer 35, and an electron injection layer 36 in addition to the light emitting layer 33 And may be in the form of a stacked layer including one layer in order.

The solvent used in the wet process for forming the light emitting layer 33 may be any known solvent as long as the light emitting material conventionally used can be dissolved or dispersed. Nonlimiting examples of the solvent include toluene, xylene, o-xylene, m-xylene, anisole, 1,2,4-trimethylbenzene or methylbenzoate, And the like. Of course, two or more of them may be used in combination.

The light emitting material constituting the light emitting layer 33 formed using the wet process may be selected from among known light emitting materials without limitation. Non-limiting examples include DPVBi, Almq, BeBq _2, TBSA, polyfluorene-based compound, a polyphenylene-based compounds, poly-phenylenevinylene-based compounds, polythiophene-based compounds, poly quinoline-based compound, a polypyrrole compound in the light-emitting material , A polyacetylene-based compound, a spirofluorene-based compound (for example, a spirofluorene compound containing an indenofluoroylene repeat unit having a spiroanthracene structure), a cyclopentaphenanthrene-based compound, an indolecarbazole unit, Polyarylene-based compounds including photographic units, derivatives thereof, and the like. It is of course possible to use a combination of two or more of them.

A hole injection layer 31 made of a hole injecting material which is inexpensive with respect to the solvent used in the wet process and a hole injection layer 31 made of a material having a low cost And a hole transporting layer 32 made of a hole transporting material. That is, at least one of the hole injection layer 31 and the hole transport layer 32 is provided directly below the light emitting layer 33 formed using the wet process.

The hole injecting material which is inexpensive with respect to the solvent used in the wet process for forming the light emitting layer 33 may be at least one selected from the group consisting of copper phthalocyanine (CuPC), triamine compound, anthracene compound, thiophene compound, Cyclohexane-based compounds, but are not limited thereto.

The hole transporting materials which are inexpensive to the solvent used in the wet process for forming the light emitting layer 33 include TCTA, NTPA, NPD, DPPD, polyphenylvinylene-based compounds, polyfluorene-based compounds, polycarbazole- , But is not limited thereto.

The hole injecting layer 31 made of the hole injecting material and the hole transporting layer 32 made of the hole transporting material are not dissolved in a conventional solvent that can be used in the wet process for forming the light emitting layer 33, (33). The hole injecting layer 31 and the hole transporting layer 32 may be formed by a known method such as a vacuum deposition method, a spin coating method, an inkjet printing method, a nozzle printing method, a spray printing method, an organic vapor jet printing method, an organic vapor phase deposition method, Can be formed through various methods.

In the case where the hole injection layer 31 is formed by the vacuum deposition method, the deposition conditions depend on the compound used as the material of the hole injection layer 31, the structure and thermal properties of the desired hole injection layer, and the like, A temperature of 100 to 500 ° C, a degree of vacuum of 10 ^-8 to 10 ^-3 torr, and a deposition rate of 0.01 to 100 Å / sec.

The thickness of the hole injection layer 31 may be about 50 to 10000 angstroms, preferably 50 to 1000 angstroms. If the thickness of the hole injection layer 31 is less than 50 ANGSTROM, the hole injection characteristics may be degraded. If the thickness of the hole injection layer 31 is more than 1000 ANGSTROM, the driving voltage may increase.

Next, a hole transport layer 32 is formed on the hole injection layer 31. The hole transporting layer 32 is formed using a hole transporting material which is insoluble in the solvent used in the wet process for forming the light emitting layer 33 as described above. Such hole transport materials are described above. The thickness of the hole transport layer 32 may be about 50 to 2000 ANGSTROM, preferably 100 to 1500 ANGSTROM. When the thickness of the hole transporting layer 32 is less than 100 ANGSTROM, the hole transporting property may be degraded. When the thickness of the HTL layer 32 is more than 1500 ANGSTROM, the driving voltage may increase.

Then, a light emitting layer 33 is formed on the hole transporting layer 32 using a wet process. The light emitting layer 33 may be formed by a variety of wet processes such as spin coating, inkjet printing, nozzle printing, and spray printing. Of these, the inkjet printing method is preferred. The material for forming the light emitting layer 33 is described above. On the other hand, it is preferable that the heat treatment temperature for removing the solvent after the application of the mixture of the material for forming the light emitting layer 33 and the solvent is appropriately selected in the temperature range of about 50 to 200 캜.

The thickness of the light emitting layer 33 may be about 100 to about 2000 ANGSTROM, preferably about 200 to about 1000 ANGSTROM. When the thickness of the light emitting layer 33 is less than 200 ANGSTROM, the light emission characteristics may be degraded. When the thickness of the light emitting layer 33 is more than 1000 ANGSTROM, the driving voltage may increase.

Thereafter, a hole blocking layer 34 may be further formed on the light emitting layer 33. The material of the hole blocking layer 34 may be Balq, BCP or the like and may be formed by a vacuum deposition method, a spin coating method, an inkjet printing method, a nozzle printing method, a spray printing method, an organic vapor jet printing method, The hole blocking layer 34 can be formed by various methods such as LB method.

The hole blocking layer 34 may have a thickness of about 50 to 1000 ANGSTROM, preferably 100 to 300 ANGSTROM. When the thickness of the hole blocking layer 34 is less than 100 ANGSTROM, hole blocking characteristics may be deteriorated. When the thickness of the hole blocking layer 34 is more than 300 ANGSTROM, the driving voltage may increase.

Next, the electron transport layer 35 is formed by various methods such as a vacuum deposition method, a spin coating method, an ink jet printing method, a nozzle printing method, a spray printing method, an organic vapor jet method, an organic vapor phase deposition method and a casting method. In the case of forming the electron transporting layer 35 by the vacuum deposition method, the conditions vary depending on the compound used, but generally, the conditions are almost the same as the formation of the hole injection layer 31. On the other hand, when the electron transporting layer 35 is formed by spin coating, the coating conditions are different depending on the structure and thermal properties of the compound used as the material of the electron transporting layer 35 and the desired electron transporting layer 35 , A coating rate of about 2000 to 5000 rpm is preferable, and a heat treatment temperature for solvent removal is suitably selected in a temperature range of about 80 to 200 캜.

The material of the electron transporting layer 35 serves to stably transport electrons injected from the cathode, and known materials such as Alq ₃ , BCP, sylol derivatives, and triazole derivatives may be used.

The thickness of the electron transporting layer 35 may be about 100 to 1000 ANGSTROM, preferably 200 to 500 ANGSTROM. When the thickness of the electron transporting layer 35 is less than 200 ANGSTROM, the electron transporting characteristics may be deteriorated. When the thickness of the electron transporting layer 35 is more than 500 ANGSTROM, the driving voltage may increase.

The electron injection layer 36, which is a material having a function of facilitating the injection of electrons from the cathode 40, may be stacked on the electron transport layer 35, which is not particularly limited.

The electron injection layer 36 material may be used any known material such as _{LiF, NaCl, CsF, Li 2} O, BaO. The deposition conditions of the electron injection layer 36 may vary depending on the compound used, but may generally be formed by vacuum deposition. The deposition rate is in the range of 0.01 to 1 Å / s, preferably 0.1 to 0.5 Å / s ≪ / RTI > If the deposition rate is less than 0.1 ANGSTROM / s, the accurate thickness can not be guaranteed, and the deposition process time can be increased. When the deposition rate exceeds 0.5 ANGSTROM / s, it is difficult to control the thickness of the electron injecting layer 36 .

The electron injection layer 36 may have a thickness of about 1 to about 500 ANGSTROM, preferably about 5 to about 50 ANGSTROM. If the thickness of the electron injection layer 36 is less than 5 ANGSTROM, the electron injection characteristics may be deteriorated. If the thickness of the electron injection layer 36 is more than 50 ANGSTROM, the driving voltage may increase.

During the process of forming the organic layer 30, the charge transfer material having vinyl end groups is mixed with the materials of the respective organic layers and mixed together through the process of forming each layer. The charge transporting material having the vinyl terminal group is formed on one of the hole injecting layer 31, the hole transporting layer 32, the light emitting layer 33, the hole blocking layer 34, the electron transporting layer 35 and the electron injecting layer 36 Or may be mixed in multiple layers.

The charge transfer material having the vinyl end group is prepared through the following reaction formula.

[Reaction Scheme]

The materials produced through the above reaction can be purified by a column chromatography using a mixed solvent of chloroform / ethyl acetate (1: 1 / v / v) as a mixture to obtain the compounds of Formulas (1) and (2). The mixed solvent may be at least one selected from the group consisting of 1,3-dimethylimidazolidinone, N-methylpyrrolidinone, N, N-dimethylacetamide, tetrahydrofuran, N, N-dimethylformamide, dimethylsulfoxide, Acetonitrile, cyclohexane, ethanol, methanol and the like, but not limited thereto. In the above reaction formula, amberlyst 15, HMOR, HPA / SiO ₂ , HZSM-5, HBEA, HY and the like can be used. The charge transfer characteristics of the material are analyzed using a pulsed nitrogen laser (Photon Technology International, Model GL-3300) and a Digital Oscilloscope (LeCroy product, model LC 574).

The organic compound readily reacts with oxygen and moisture in an excited state to generate a new compound structure, and when the oxygen and moisture are introduced into the organic electroluminescent device due to such an influence, the luminescent property is reduced. The charge transfer material having the vinyl terminal group may undergo an electrophilic addition reaction with moisture introduced into the organic electroluminescent device or may be oxidized by oxygen to reduce deterioration of the organic layer 30 due to moisture and oxygen, .

Finally, the cathode 40 may be formed on the electron injection layer 36 by a vacuum evaporation method, a sputtering method, or the like. As the metal for forming the cathode 40, a metal, an alloy, an electrically conductive compound having a low work function, and a mixture thereof may be used. Specific examples thereof include Li, Mg, Ba, Al, Al-Li, Al-Ba, Mg-In, - silver (Mg-Ag), and the like.

[0044] The organic electroluminescent device of the present invention and the method of manufacturing the same according to the present invention have been described with reference to FIG. 1, but various modifications other than the structure shown in FIG. 1 are possible.

The organic electroluminescent device according to the present invention may be provided in various types of flat panel display devices, for example, a passive matrix (PM) organic light emitting display device and an active matrix (AM) organic light emitting display device. In particular, in an AM organic light emitting display, the anode may be electrically connected to a source electrode or a drain electrode of the thin film transistor provided in the AM organic light emitting display.

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited thereto.

[Example 1]

A 1300 A thick substrate 10 (manufactured by SDI) coated with an anode 20 made of aluminum and indium tin oxide was cut into a size of 50 mm x 50 mm x 0.7 mm and ultrasonically cleaned in isopropyl alcohol and pure water for 5 minutes Then, the substrate 10 on which the anode 20 is formed is prepared by irradiating with UV for 30 minutes and washing with ozone.

Copper phthalocyanine (manufactured by Sigma-Aldrich), which is a hole injecting material, is deposited on the anode 20 to form a 200 Å thick hole injection layer 31.

(3)

A polyfluorene polymer (manufactured by Sumitomo Chemical Co., Ltd.) was prepared as a polymer light emitting material on the hole injection layer 31, and then dissolved in toluene together with a charge transfer material (Formula 3) having a vinyl end group content of 5 wt% A 500 Å thick light emitting layer 33 is formed by spin coating. Alq ₃ (manufactured by Sigma-Aldrich) is deposited on the light emitting layer 33 to form an electron transporting layer 35 having a thickness of 300 Å. LiF was deposited on the electron transport layer 35 to a thickness of 5 Å to form an electron injection layer 36. Magnesium-silver (Mg-Ag) was formed to a thickness of 180 Å as the cathode 40, Thereby preparing a light emitting device.

[Example 2]

An organic electroluminescent device was prepared in the same manner as in Example 1, except that the charge transport material having the vinyl terminal group was represented by the following formula (4).

[Chemical Formula 4]

[Comparative Example]

An organic electroluminescence device was prepared in the same manner as in Example 1, except that the charge transport material having the vinyl end group was not used.

It was confirmed that the driving time before the occurrence of the pixel shrinkage phenomenon after the completion of the organic EL device was compared with the driving time.

10: substrate 20: anode
30: organic layer 40: cathode
100: organic electroluminescent device

Claims (6)

Anode;
An organic layer mixed with a charge transfer material having a vinyl terminal group; And
And a cathode,
Wherein the charge transport material having the vinyl terminal group comprises a compound represented by the following formula (1).
[Chemical Formula 1]

In the above formula (1), R is a compound having a carbon number of 1 having a cyano group. Anode;
An organic layer mixed with a charge transfer material having a vinyl terminal group; And
And a cathode,
Wherein the charge transport material having the vinyl terminal group comprises a compound represented by the following formula (2).
(2)

In the above formula (2), R is a compound having a carbon number of 1 having a cyano group. The method according to claim 1,
Wherein the organic layer between the anode and the cathode can be composed of multiple layers. 3. The method of claim 2,
Wherein the organic layer between the anode and the cathode can be composed of multiple layers. The method according to claim 1,
Wherein the anode is formed on a glass substrate or a transparent plastic substrate. 3. The method of claim 2,
Wherein the anode is formed on a glass substrate or a transparent plastic substrate.

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