KR100622230B1 - Organic electroluminescent display devices and method for preparing the same - Google Patents

Abstract

The present invention relates to an organic electroluminescent display and a method of manufacturing the organic electroluminescent display according to the present invention, wherein the organic electroluminescent display includes at least two organic material layers between a pair of electrodes, wherein the one organic material layer is a light emitting layer, and Another organic layer is a carrier transport layer doped with a metal phthalocyanine-based organic compound of a p-type semiconductor material of the following formula:

Wherein R is each independently or independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkoxy group, an ester group, an amide group, an aryl group having 6 to 12 carbon atoms, an arylamine group, a heterocyclic compound, a halogen group, Nitro or nitrile (-CN) groups.

The organic light emitting display device according to the present invention can improve the carrier transport layer, prevent leakage of current, improve driving efficiency by lowering the driving voltage, and extend the lifespan of the light emitting display device.

Metal phthalocyanine-based organic compound, p-type semiconductor material, carrier transport layer

Description

Organic Electroluminescent Display Devices and Method for Preparing the Same

1 illustrates a structure of a light emitting display device according to an exemplary embodiment of the present invention.

2 is a flowchart illustrating a method of manufacturing a light emitting display device according to an embodiment of the present invention.

3 is a flowchart illustrating a method of manufacturing a light emitting display device according to another embodiment of the present invention.

The present invention relates to an organic electroluminescent display and a method of manufacturing the same. More specifically, the present invention relates to an organic electroluminescent display device and a method of manufacturing the same, wherein the metal phthalocyanine-based organic compound is doped with a P-type semiconductor material to improve a carrier transport layer, lower driving voltage, and improve efficiency and lifespan characteristics.

Recently, an organic light emitting display device has attracted attention as a next generation display device due to advantages such as thin, wide viewing angle, light weight, small size, fast response speed, and power consumption, compared to a cathode ray tube (CRT) or a liquid crystal device (LCD).

In particular, since the organic light emitting display device has a simple structure of an anode, an organic material layer, and a cathode, there is an advantage that it can be easily manufactured through a simple manufacturing process. The organic material layer may be composed of several layers according to its function. In general, the organic material layer may include a light emitting layer and a carrier transport layer, and the carrier transport layer may include a hole injection layer and / or a hole transport layer close to the anode side, an electron transport layer close to the cathode side, and And / or an electron injection layer, which is laminated in the order of anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode.

The light emitting process of the light emitting display will be described below. That is, holes are injected from the anode, which is a transparent electrode, and the injected holes are transferred to the light emitting layer through the hole injection layer and the hole transport layer, and electrons are injected from the cathode and transferred to the light emitting layer through the electron injection layer and the electron transport layer. Electrons and holes combine to emit light in the light emitting layer. The light emitting layer has a structure in which a dopant is doped in a host, and electrons and holes are transferred to the dopant through the host to emit light.

Until now, various methods for improving the performance of the organic light emitting display have been proposed. In view of the light emitting material, a method for developing a new structure and improving each layer constituting the display device has been proposed.

For example, when the hole injection layer, which is a layer for facilitating hole injection from the anode to the hole transport layer or the light emitting layer, has a work function similar to the anode, driving voltage, efficiency, and lifetime of the light emitting display device can be improved.

Documents that disclose that the hole injection layer can be improved to improve driving voltage, efficiency and lifespan are disclosed in WO03 / 070822. The document discloses that the driving voltage is reduced by doping tetracyanodiquinomethane in the hole injection layer.

In addition, according to US Patent Application Publication No. 2002-0158242, in order to facilitate hole injection and transfer from the electrode to the light emitting layer, p-type semiconductor material of the following formula (1) is used as the main material of the hole injection layer and / or hole transport layer Use is disclosed:

Wherein R is each independently or independently hydrogen, alkyl group having 1 to 12 carbon atoms, alkenyl group, alkoxy group, ester group, amide group, aryl group having 6 to 12 carbon atoms, arylamine group, heterocyclic compound, halogen group, nitro Groups and nitrile (—CN) groups.

  Since the p-type semiconductor material of Chemical Formula 1 has excellent hole mobility, the display device including the p-type semiconductor material has a low driving voltage, and has a service life characteristic superior to that of other hole injection layer materials. The p-type semiconductor material has a disadvantage of causing a lot of defects due to poor interface characteristics with the electrode, which causes a problem of leakage of current when a reverse voltage is applied. This must be preceded.

Therefore, the inventors of the present invention, while studying a way to solve the current leakage problem by using the p-type semiconductor material of Formula 1, rather than using the p-type semiconductor material as the main carrier transport material, in particular hole transport material, When doped with a p-type semiconductor material at an appropriate amount of use for a general hole transporting material such as a metal phthalocyanine-based organic compound, the lifespan of the organic light emitting display can be improved while increasing efficiency and improving the lifetime without a current leakage problem. The present invention was completed.

Accordingly, an object of the present invention is to combine an organic metal phthalocyanine-based compound and a p-type semiconductor material in a carrier transport layer to solve a current leakage problem while lowering driving voltage and improving efficiency and lifespan. To provide a device.

Another technical problem to be solved by the present invention is to combine a metal phthalocyanine-based organic compound and a p-type semiconductor material in a carrier transport layer to solve the current leakage problem while lowering the driving voltage and improving the efficiency and lifetime of the organic electroluminescent display It is to provide a method of manufacturing the device.

In order to achieve the first technical problem, in an organic light emitting display device including at least two organic material layers between a pair of electrodes, the one organic material layer is a light emitting layer, the other organic material layer is a metal phthalocyanine-based organic compound An organic light emitting display device, which is a carrier transport layer doped with a p-type semiconductor material of Formula 1, is provided:

Formula 1

Wherein R is each independently or independently hydrogen, alkyl group having 1 to 12 carbon atoms, alkenyl group, alkoxy group, ester group, amide group, aryl group having 6 to 12 carbon atoms, arylamine group, heterocyclic compound, halogen group, nitro Group or nitrile group.

In the organic light emitting display device according to the present invention, the content of the p-type semiconductor material of Chemical Formula 1 doped into the metal phthalocyanine organic compound constituting the carrier transport layer is preferably 0.1 to 30% by weight.

In the organic electroluminescent display according to the present invention, the metal phthalocyanine-based organic compound is copper phthalocyanine, and the p-type semiconductor material is preferably a R group nitrile (-CN) group in Chemical Formula 1.

In addition, the carrier transport layer is preferably a hole injection layer or a hole transport layer, the thickness of the carrier transport layer formed by doping the metal phthalocyanine-based organic compound of the formula (1) is preferably 1 to 20nm.

In order to achieve the second technical problem, the present invention comprises the steps of forming a first electrode on the substrate; Forming a carrier transport layer on the first electrode; Forming a light emitting layer on the carrier transport layer; And forming a second electrode on the emission layer, wherein the carrier transport layer is formed by doping a metal phthalocyanine-based organic compound with a p-type semiconductor material of Formula 1 below. Provides:

Formula 1

Wherein R is each or independently hydrogen, alkyl group having 1 to 12 carbon atoms, alkenyl group, alkoxy group, arylamine group, ester group, amide group, aryl group having 6 to 12 carbon atoms, heterocyclic compound, halogen group, nitro Group and nitrile group.

In the method of manufacturing the organic light emitting display device according to the present invention, the doping concentration of the p-type semiconductor material is preferably 0.1% to 30% by weight.

In the method of manufacturing an organic light emitting display device according to the present invention, it is preferable that the metal phthalocyanine-based organic compound is copper phthalocyanine, and the p-type semiconductor material is R in the formula (1).

In addition, the carrier transport layer is preferably a hole injection layer or a hole transport layer, the thickness of the carrier transport layer formed by doping the metal phthalocyanine-based organic compound of the formula (1) is preferably 1 to 20nm.

Hereinafter, with reference to the accompanying drawings the present invention will be described in more detail.

The organic electroluminescent display according to the present invention is based on a stacked structure of a first electrode, an organic layer, and a second electrode, and the organic layer includes a carrier transport layer doped with a light emitting layer and a metal phthalocyanine-based organic compound with a p-type semiconductor material. It is characterized by including.

In the organic electroluminescent display, the carrier transport layer includes a hole injection layer or a hole transport layer near the anode side, and an electron injection layer or an electron transport layer near the cathode side, and these may be suitably employed, for example, a first electrode (anode). Electrode) / hole injection layer / hole transport layer / light emitting layer / second electrode (cathode electrode) or an anode electrode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / It may be composed of a cathode electrode, and many other structures are possible.

1 illustrates a structure of an organic light emitting display device according to an embodiment of the present invention.

Referring to FIG. 1, an organic light emitting display device according to the present invention has a structure including a light emitting layer 50 between an anode electrode 20 and a cathode electrode 80, and the anode electrode 20 and the light emitting layer 50. The hole injection layer 30 and the hole transport layer 40 are included in between, and the electron transport layer 50 and the electron injection layer 70 are included between the light emitting layer 50 and the cathode electrode 80.

2 is a flowchart illustrating a method of manufacturing a light emitting display device according to an embodiment of the present invention, and FIG. 3 is a flowchart illustrating a method of manufacturing a light emitting display device according to another embodiment of the present invention.

1 to 3, an organic light emitting display device according to the present invention is manufactured through the following process. First, the anode electrode 20 is formed by coating an anode electrode material on the substrate 10 (S11). Here, the substrate 10 may be a substrate generally used in this field, and a glass substrate or a transparent plastic substrate excellent in transparency, surface smoothness, ease of handling, and waterproofness is particularly preferable. In addition, as an anode electrode material formed on the substrate, indium tin oxide (ITO), tin oxide (SnO ₂ ), zinc oxide (ZnO), and the like, which are transparent and have excellent conductivity, may be used.

A hole injection layer 30 is formed on the anode electrode 20 (S12). The hole injection layer 30 may be formed by doping a metal phthalocyanine-based organic compound with a p-type semiconductor material through a conventional method such as vacuum deposition or spin coating, or generally used in the hole injection layer. Material, for example CuPc (copper phthalocyanine) or IDE 406 (Idemitsu Kosan).

Subsequently, the hole transport layer 40 is formed on the hole injection layer 30 (S13). The hole transport layer 40 may be formed through a conventional method such as vacuum deposition or spin coating, and the hole transport layer 40 may be formed by doping a metal phthalocyanine-based organic compound with a p-type semiconductor material, or General hole transport materials, for example N, N'-di (1-naphthyl) -N, N'-diphenylbenzidine (NPD), bis (4-dimethylamino-2-methylphenyl) phenylmethane, 1 Be formed using at least one kind of 1-bis (4-di-p-tolylaminophenyl) cyclohexane, 1,1, -bis (4-di-p-tolylaminophenyl) -4-phenyl cyclohexane, and the like. Can be.

However, at least one layer of the hole injection layer 30 and the hole transport layer 40 is preferably formed by doping a metal phthalocyanine-based organic compound with a p-type semiconductor material. In addition, when the hole injection layer 30 or the hole transport layer 40 is formed by doping the metal phthalocyanine-based organic compound with a p-type semiconductor material, the thickness of each layer is within the range of 1 to 20 nm thinner than the general thickness. Can be formed.

Copper phthalocyanine may be used as the metal phthalocyanine-based organic compound, and as the p-type semiconductor material, it is preferable to use a material having a hole mobility greater than the electron mobility, and specifically, the compound of Formula 1 may be used. And particularly preferably R is a nitrile group:

Formula 1

Wherein R is each independently or independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkoxy group, an ester group, an amide group, an aryl group having 6 to 12 carbon atoms, an arylamine group, a heterocyclic compound, a halogen group, Nitro or nitrile groups.

The p-type semiconductor material with respect to the metal phthalocyanine-based organic compound is preferably doped in the range of 0.1 to 30% by weight, more preferably 0.1 to 10% by weight. When the p-type semiconductor material is used in less than 0.1% by weight, the effect of the addition of the p-type semiconductor material may be insignificant, and when used in excess of 30% by weight, poor interface properties with the electrode is poor There is a problem that can be generated a lot, thereby leaking the current when the reverse voltage is applied. By doping the metal phthalocyanine-based organic compound within the range of 0.1 to 30% by weight, the carrier concentration is increased and the interface energy barrier is removed to facilitate the injection of holes, and the efficiency of the display device is improved by eliminating defects. It has a synergistic effect, and thus lifespan characteristics are also improved.

Subsequently, the light emitting layer 50 is formed on the hole transport layer 40 through a conventional method, for example, vacuum deposition, spin coating, or the like (S14). The light emitting layer material is not particularly limited, and is formed by doping a conventional host such as carbazole biphenyl (CBP) by doping with a conventional dopant such as iridium tris (phenylpyridine) (Irppy ³ ). Can be.

The hole suppression layer may be selectively formed on the emission layer 50 before the electron transport layer 60 is formed. The hole suppression layer may be formed through a conventional method, and non-phenoxy-bi (8-quinolinolato) aluminum (BAlq) may be used as the hole suppressing material, although not limited thereto.

Further, the electron transport layer 60 is formed on the light emitting layer 50 or on the hole suppression layer (S15). The electron transport layer forming step S15 is also an optional process. A vacuum deposition method or a spin coating method may be used to form the electron transport layer, and the material for the electron transport layer is not particularly limited, but may be an aluminum complex (eg, Alq (tris (8-quinolinolato) -aluminum)). Can be used.

The electron injection layer 70 may be selectively formed on the electron transport layer 60 using a method such as vacuum deposition or spin coating (S16). In this case, the material for the electron injection layer 70 is not particularly limited, but materials such as LiF, NaCl, and CsF may be used.

Subsequently, the cathode electrode 80 is formed on the electron injection layer 70 through vacuum deposition (S17) to complete the organic light emitting display device. The metal for the cathode is calcium (Ca), magnesium (Mg), lithium fluoride-aluminum (LiF / Al), barium (Ba), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag ) Is used. After the cathode electrode 80 is deposited, an organic light emitting display device is manufactured through an encapsulation process.

Accordingly, the light emitting display device according to the present invention has a stacked structure as shown in FIG. 1, and may further form one or two intermediate layers, for example, a hole suppression layer, if necessary, and may be omitted. . In addition, the thickness of each layer of the light emitting display device may be determined as needed within the range generally used in the art.

Hereinafter, a preferred embodiment of the present invention. However, the following examples are only presented to aid the understanding of the present invention, and the present invention is not limited to the following examples.

Example 1

On the surface of the substrate on which the ITO film was formed as the anode electrode, copper phthalocyanine was doped with a p-type semiconductor material of Formula 1 (R is a nitrile group) at a concentration of 10% and co-deposited under 10 ^-6 Torr vacuum to form a hole injection layer. Formed to nm thickness:

Formula 1

Subsequently, 50 nm was deposited under vacuum of 10 ^-6 Torr using N, N'-di (1-naphthyl) -N, N'-diphenylbenzidine (NPD) as a hole transporting material on the hole injection layer. A hole transport layer was formed to a thickness of. After the formation of the hole transport layer, the light emitting layer was formed on carbazole biphenyl (CBP) by depositing iridium tris (phenylpyridine) (Irppy ³ ) at a concentration of 5% under a condition of 10 ⁻⁶ to 10 ⁻⁷ torr to a thickness of 30 nm. After deposition of the light-emitting layer, a non-phenoxy-bi (8-quinolinolato) aluminum was deposited as a hole suppression layer at a thickness of 5 nm under a condition of 10 ⁻⁶ to 10 ⁻⁷ torr, and then tris (8-quinoli) as an electron transport layer. Lato) aluminum (Alq) was deposited under a vacuum of 10 ⁻⁶ Torr to a thickness of 20 nm. LiF was deposited on the electron transport layer on the LiF electron injection layer using Al as a metal electrode after deposition of LiF at a thickness of 1 nm under the condition of 10 ^-6 to 10 ^-7 torr. An organic light emitting display device was manufactured by encapsulating the metal can and barium oxide.

Example 2

An organic light emitting display device was manufactured in the same manner as in Example 1, except that the doping concentration of the p-type semiconductor material of Formula 1 was 30% by weight.

Comparative Example 1

On the substrate surface on which the ITO film was formed as the anode electrode, copper phthalocyanine was deposited under a vacuum of 10 ⁻⁶ torr to form a hole injection layer having a thickness of 20 nm. Subsequently, 50 nm was deposited under a vacuum of 10 ^-6 Torr using N, N'-di (1-naphthyl) -N, N'-diphenylbenzidine (NPD) as a hole transporting material on the hole injection layer. A hole transport layer was formed to a thickness of. After the hole transport layer formation including the iridium jolbi phenyl (CBP) cover a light-emitting layer and the first phosphorescent dopant, a maximum emission wavelength 608㎚ agent (bis (1-phenyl-quinoline) iridium acetylacetonate) at a concentration of 12% 10 ^{- It} was deposited under the condition of 6˜10 ⁻⁷ torr to form a thickness of 30 nm. After deposition of the light-emitting layer, a non-phenoxy-bi (8-quinolinolato) aluminum was deposited with a hole suppression layer at a thickness of 5 nm under a condition of 10 ^-6 to 10 ^-7 torr, and then Alq was 10 ^-6 Torr as an electron transporting layer. Was deposited under a vacuum of 20 nm in thickness. The electron transport layer The electron injection layer is a LiF in 10 ^-6 to 10 ^-7 torr and then deposited under the conditions of, 300㎚ thickness on the LiF electron injection layer by using Al as the metal electrode to a thickness of ^10-6 to 1㎚ After depositing under a condition of ˜10 ⁻⁷ torr, an organic light emitting display device was manufactured by encapsulating the metal can and barium oxide.

Comparative Example 2

An organic light emitting display device was manufactured in the same manner as in Example 1, except that the doping concentration of the p-type semiconductor material of Formula 1 was 0.05% by weight.

Test Example 1

In the organic light emitting display devices manufactured in Examples 1 and 2 and Comparative Examples 1 and 2, luminance, efficiency, lifetime, and leakage current density at 6V were measured, and the results are shown in Table 1 below.

Luminance (8 V) Efficiency (cd / A) Life (hours) * Leakage current density (mA / ㎠) Example 1 3800 29.7 2000 10 ^-5 Example 2 3700 30.0 1800 10 ^-2 Comparative Example 1 3200 27.0 1000 10 ^-5 Comparative Example 2 3200 27.0 1000 10 ^-5

Lifespan: When the display device is driven at 4300 cd / m 2, it exhibits a half-life life of up to 50% of luminance.

As shown in Table 1, Example 1 in which 10% of the p-type semiconductor material was doped with copper phthalocyanine as the hole injection layer, compared with the case of Comparative Example 1 without using the p-type semiconductor material, It can be seen that not only the efficiency is improved but also the life is significantly increased. On the other hand, in the case of Comparative Example 2 having a doping concentration of 0.05% of the p-type semiconductor material, it can be seen that there is no difference in performance from Comparative Example 1 without using the p-type semiconductor material. On the other hand, when comparing Examples 1 and 2, it was found that the leakage current density increases in Example 2, which is almost similar in brightness, efficiency, and lifetime, but uses a large amount of p-type semiconductor material.

From this fact, it can be seen that the doping concentration of the p-type semiconductor material is preferably used in the range of 0.1 to 30% by weight.

The organic electroluminescent display according to the present invention can be fabricated by using a combination of copper phthalocyanine and p-type semiconductor material to improve the carrier transport layer, thereby improving the current leakage, brightness, efficiency and lifespan.

Claims (10)

An organic light emitting display device including at least two organic material layers between a pair of electrodes, wherein the one organic material layer is a light emitting layer, and the other organic material layer is formed of a metal phthalocyanine organic compound with a p-type semiconductor material of Formula 1 An organic electroluminescent display that is a doped carrier transport layer: Formula 1

Wherein R is each independently or independently hydrogen, alkyl group having 1 to 12 carbon atoms, alkenyl group, alkoxy group, ester group, amide group, aryl group having 6 to 12 carbon atoms, arylamine group, heterocyclic compound, halogen group, nitro Group or nitrile group. The organic light emitting display device of claim 1, wherein a content of the p-type semiconductor material of Chemical Formula 1 doped into the metal phthalocyanine organic compound constituting the carrier transport layer is 0.1 to 30 wt%. The organic light emitting display device of claim 1, wherein the metal phthalocyanine-based organic compound is copper phthalocyanine, and the p-type semiconductor material is a nitrile group having an R group represented by Chemical Formula 1. The organic light emitting display device of claim 1, wherein the carrier transport layer is a hole injection layer or a hole transport layer. The organic light emitting display device of claim 1, wherein a thickness of a carrier transport layer formed by doping the metal phthalocyanine-based organic compound with the p-type semiconductor material of Chemical Formula 1 is 1 to 20 nm. Forming a first electrode on the substrate; Forming a carrier transport layer on the first electrode; Forming a light emitting layer on the carrier transport layer; And Forming a second electrode on the light emitting layer; Wherein the carrier transport layer is formed by doping a metal phthalocyanine-based organic compound with a p-type semiconductor material of Formula 1 below: Formula 1

Wherein R is each independently or independently hydrogen, alkyl group having 1 to 12 carbon atoms, alkenyl group, alkoxy group, ester group, amide group, aryl group having 6 to 12 carbon atoms, arylamine group, heterocyclic compound, halogen group, nitro Group or nitrile group.  The method of claim 6, wherein the doping concentration of the p-type semiconductor material is 0.1 wt% to 30 wt%. The method of claim 6, wherein the metal phthalocyanine-based organic compound is copper phthalocyanine, and the p-type semiconductor material is R in nitrile. The method of claim 6, wherein the carrier transport layer is a hole injection layer or a hole transport layer. The method of claim 6, wherein the carrier transport layer formed by doping the metal phthalocyanine-based organic compound with the p-type semiconductor material of Chemical Formula 1 is formed to a thickness of 1 to 20 nm.

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