KR100751357B1 - An organic electroluminescent device and a flat display device comprising the same - Google Patents

Abstract

The present invention is a first electrode; Second electrode; And an emission layer between the first electrode and the second electrode, wherein the organic light emitting element comprises an intermediate layer including a charge transfer control material between the second electrode and the emission layer. A flat panel display device provided with the organic light emitting element.

According to the present invention, it is possible to provide an organic light emitting device having increased efficiency and luminance and a low driving voltage and a flat panel display device having the same.

Description

An organic electroluminescent device and a flat display device comprising the same

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

2 is a schematic cross-sectional view showing an organic light emitting device according to the present invention so as to simultaneously display the respective light emitting colors.

3 to 6 are diagrams showing current density, luminance, current efficiency, and power efficiency of the red organic light emitting diodes according to the present invention and the red organic light emitting diode according to the prior art, respectively.

7 and 8 are diagrams illustrating current efficiency and power efficiency of the green organic light emitting diode according to the present invention and the green organic light emitting diode according to the prior art, respectively.

<Description of Signs for Main Parts of Drawings>

210: first electrode 216: hole injection layer

218: hole transport layer 220, 225, 230: light emitting layer

222: hole suppression layer 224: intermediate layer

240: electron transport layer 250: electron injection layer

260: second electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting device and a flat panel display. More particularly, by providing an intermediate layer including a charge transfer control material between a second electrode or an opposite electrode and a light emitting layer, efficiency and brightness are increased, and a driving voltage is increased. A low organic light emitting device and a flat panel display device having the same.

An organic light emitting device is a self-luminous device using a phenomenon in which light is generated when electrons and holes are combined in an organic layer when a current flows through a fluorescent or phosphorescent organic film. Have In addition, high-definition can be realized, wide viewing angle can be obtained, and video can be fully realized. In addition, high color purity, low power consumption, and low voltage driving are possible, and thus have electrical characteristics suitable for portable electronic devices.

In order to improve efficiency and lower driving voltage, the organic light emitting diode generally uses a multi-layer structure such as an electron injection layer, a light emitting layer, a hole transport layer, etc., instead of using a single light emitting layer. For example, Japanese Patent Laid-Open No. 2002-252089 discloses an organic light emitting device having a hole transport layer.

At present, various methods for increasing efficiency and luminance of a conventional organic light emitting device and lowering driving voltage thereof have been proposed. As a part of these efforts, efforts have been made to achieve various purposes by inserting various intermediate layers into a stacked structure of an organic light emitting device. It is going on.

According to the present invention, by inserting an intermediate layer containing a material capable of controlling charge mobility into a conventional laminated structure of an organic light emitting device, the organic light emitting device has excellent efficiency and luminance and lower driving voltage than the conventional organic light emitting device. The present invention provides a light emitting device and a flat panel display device having the same.

In order to achieve the above object of the present invention, the first aspect of the present invention,

A first electrode; Second electrode; And an emission layer between the first electrode and the second electrode, wherein the intermediate layer comprises a charge transfer control material between the second electrode and the emission layer. to provide.

According to another aspect of the present invention, a second aspect of the present invention includes an organic light emitting device as described above, wherein the first electrode of the organic light emitting device is electrically connected to a source electrode or a drain electrode of a thin film transistor. Provided is a flat panel display device.

Hereinafter, the present invention will be described in more detail.

The organic light emitting device according to the present invention has an effect of increasing efficiency and brightness and lowering driving voltage by providing an intermediate layer including a charge transfer control material between the second electrode or the counter electrode and the light emitting layer.

Hereinafter, an embodiment and a method of manufacturing the organic light emitting diode according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 schematically illustrates a cross-sectional view of an organic light emitting device according to the present invention, and FIG. 2 illustrates an organic light emitting device according to the present invention so as to simultaneously display each light emitting color.

First, a first electrode (pixel electrode or anode electrode) 210 is formed on the substrate 200. Herein, the substrate 200 may be a substrate used in a conventional organic light emitting device. In consideration of transparency, surface smoothness, ease of handling, and waterproofness, an organic substrate or a plastic substrate may be variously used. The first electrode 210 is a metal having excellent conductivity, such as lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium ( Various modifications are possible, such as Mg-In), magnesium-silver (Mg-Ag), calcium (Ca) -aluminum (Al), aluminum (Al) -ITO, and the like, which may be provided as reflective electrodes.

Thereafter, the pixel defining film 214 defining the organic layer formation region is formed at a predetermined position. The pixel defining layer may be formed using various methods such as a deposition method or a coating method using inorganic or insulating organic materials such as silicon oxide and nitride.

The hole injection layer 216 and the hole transport layer 218 are sequentially formed by vacuum thermal deposition or spin coating on the first electrode 210 along the region defined by the pixel defining layer 214.

The material constituting the hole injection layer provided in the organic light emitting device according to the present invention is not particularly limited. Specific examples include copper phthalocyanine (CuPc) or starburst amines TCTA, m-MTDATA, IDE406 (from Idemitsu Corp.), Pani / DBSA (Polyaniline / Dodecylbenzenesulfonic acid: polyaniline / dodecylbenzenesulfonic acid) or PEDOT / PSS (Poly (3,4-ethylenedioxythiophene) / Poly (4-styrenesulfonate): poly (3,4-ethylenedioxythiophene) / poly (4-styrenesulfonate)) and the like, but are not limited thereto. .

                 Pani / DBSA

                 PEDOT / PSS

The material constituting the hole transporting layer provided in the organic light emitting device according to the present invention is also not particularly limited. As a specific example, 1,3,5-tricarbazolylbenzene, 4,4'-biscarbazolylbiphenyl, polyvinylcarba Sol, m-biscarbazolylphenyl, 4,4'-biscarbazolyl-2,2'-dimethylbiphenyl, 4,4 ', 4 "-tri (N-carbazolyl) triphenylamine, 1,3, 5-tri (2-carbazolylphenyl) benzen, 1,3,5-tris (2-carbazolyl-5-methoxyphenyl) benzene, bis (4-carbazolylphenyl) silane, N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1-biphenyl] -4,4'diamine (TPD), N, N'-di (naphthalen-1-yl) -N, N ' -Diphenyl benzidine (α-NPD), N, N'-diphenyl-N, N'-bis (1-naphthyl)-(1,1'-biphenyl) -4,4'-diamine (NPB) , IDE320 (manufactured by Idemitsu Co., Ltd.), poly (9,9-dioctylfluorene-co-N- (4-butylphenyl) diphenylamine) (poly (9,9-dioctylfluorene-co-N- (4- butylphenyl) diphenylamine) (TFB) or poly (9,9-dioctylfluorene-co-bis-N, N-phenyl-1,4-phenylenediamine (poly (9,9-dioctylfl uorene-co-bis- (4-butylphenyl-bis-N, N-phenyl-1,4-phenylenediamin) (PFB) and the like, but are not limited thereto.

The light emitting layers 220, 225, and 230 for each color are formed on the hole injection layer 216 and the hole transport layer 218. The material constituting the light emitting layer of the present invention is not particularly limited.

The red light-emitting layer includes, for example, DCM1, DCM2, Eu (thenoyltrifluoroacetone) 3 (Eu (TTA) 3, butyl-6- (1,1,7,7-tetramethyl zulolidil-9-enyl) -4H-pyran ) (butyl-6- (1,1,7,7, -tetramethyljulolidyl-9-enyl) -4H-pyran: DCJTB) And the like can be used. Alternatively, Alq3 may be formed by doping a dopant such as DCJTB, or by co-depositing Alq3 and rubrene and doping the dopant, 4,4'-N, N'-dicarbazole-biphenyl (4,4'-N Various modifications are possible, such as doping of a dopant such as BTPIr to -N'-dicarbazole-biphenyl) (CBP).

             DCJTB

For example, coumarin 6, C545T, quinacridone, Ir (ppy) _3, or the like may be used as the green light emitting layer. On the other hand, various modifications are possible, such as using Ir (ppy) 3 as a dopant for CBP or coumarin-based material as a dopant for Alq 3 as a host. Specific examples of the coumarin dopant include C314S, C343S, C7, C7S, C6, C6S, C314T, and C545T.

The blue light emitting layer may include, for example, oxadiazole dimer dyes (Bis-DAPOXP), spiro compounds (Spiro-DPVBi, Spiro-6P), triarylamine compounds, and bis ( Styryl) amine (bis (styryl) amine) (DPVBi, DSA), compound (A) Flrpic, CzTT, Anthracene, TPB, PPCP, DST, TPA, OXD-4, BBOT, AZM-Zn, naphthalene moiety BH-013X (Idemitsu Co., Ltd.), which is an aromatic hydrocarbon compound, can be used in various ways. On the other hand, various modifications are possible, such as IDE105 (trade name, product of Idemitsu Co., Ltd.) can be used as a dopant for IDE140 (trade name, product of Idemitsu Co., Ltd.).

The thickness of the light emitting layer is 100 kPa to 500 kPa, preferably 100 kPa to 400 kPa. Meanwhile, the thicknesses of the light emitting layers in the R, G, and B regions may be the same or different from each other. If the thickness of the light emitting layer is less than 200 kW, the lifetime is reduced, and if the thickness of the light emitting layer is more than 500 kW, the driving voltage rise is high, which is not preferable.

The hole suppression layer 222 may be selectively formed by vacuum deposition or spin coating a material for blocking holes on the light emitting layer. The material for the hole suppression layer used at this time is not particularly limited, but should have ionization potential higher than that of the light emitting compound while having an electron transport ability, and typically, bis (2-methyl-8-quinolato)-(p-phenylphenolato) -aluminum ( Balq), bathocuproine (BCP), tris (N-arylbenzimidazole) (TPBI), and the like.

The thickness of the hole suppression layer 222 is 30 kPa to 60 kPa, preferably 40 kPa to 50 kPa. If the thickness of the hole suppression layer 222 is less than 30 kW, hole suppression characteristics may not be well implemented, and if the thickness of the hole suppression layer 222 is more than 60 kW, the driving voltage may increase, which is not preferable.

Preferably, the organic light emitting diode according to the present invention includes an intermediate layer 224 including a charge transfer control material on the hole suppression layer 222.

Preferably, the charge transfer control material is at least one material selected from the group consisting of distyrylanthracene derivatives, distyryltetracene derivatives and diphenylvinyl derivatives.

Preferably, the charge mobility of the interlayer 224 including the charge transfer control material is lower than the charge mobility of the electron transport layer and the hole suppression layer, and more preferably has electron transfer characteristics rather than hole transfer characteristics.

Further, preferably, the thickness of the intermediate layer including the charge transfer control material is 50 kPa to 150 kPa.

Subsequently, an electron transport material 240 is vacuum deposited or spin coated on the intermediate layer 224 to selectively form an electron transport layer 240. The electron transporting material is not particularly limited and may be Alq 3 or the like.

The electron transport layer 240 has a thickness of 100 kPa to 400 kPa, preferably 250 kPa to 350 kPa. If the thickness of the electron transport layer 240 is less than 100 kV, the electron transport speed may be excessive and the charge balance may be broken. If the electron transport layer 240 exceeds 400 kV, the driving voltage may be increased.

The electron injection layer 250 may be formed on the emission layer, the hole suppression layer, or the electron transport layer by using a vacuum deposition method or a spin coating method. Materials for forming the electron injection layer 250 may include materials such as BaF ₂ , LiF, NaCl, CsF, Li ₂ O, BaO, Liq, but are not limited thereto.

The thickness of the electron injection layer 250 may be 2 kPa to 10 kPa, preferably 2 kPa to 5 kPa. Among these, 2 GPa-4 GPa are especially suitable thickness. When the thickness of the electron injection layer 250 is less than 2 kV, it may not play a role as an effective electron injection layer, and when the thickness of the electron injection layer 250 exceeds 10 kV, the driving voltage may increase. Not desirable

Subsequently, the organic light emitting device is completed by depositing a second electrode (counter electrode or cathode electrode) 260 on the electron injection layer.

As mentioned above, although an embodiment of the organic light emitting device and a method of manufacturing the same have been described with reference to FIGS. 1 and 2, the organic light emitting device according to the present invention is not limited to the above-described structure, and the organic light emitting device has various structures. The device is possible.

In another aspect, the present invention provides a flat panel display device including the organic light emitting diode as described above, wherein the first electrode of the organic light emitting diode is electrically connected to a source electrode or a drain electrode of the thin film transistor.

The organic light emitting diode according to the present invention may be provided in various types of flat panel display devices, for example, passive matrix organic light emitting display devices and active matrix organic light emitting display devices. In particular, when the active matrix organic light emitting display device is provided, the pixel electrode may be electrically connected to a source electrode or a drain electrode of the thin film transistor.

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

Example  1 (red element)

As a reflective first electrode, a 1300Å thick (aluminum and ITO) (SDI) substrate was cut into 50 mm x 50 mm x 0.7 mm and ultrasonically cleaned in isopropyl alcohol and pure water for 5 minutes and then for 30 minutes. UV and ozone cleaning were used.

A hole injection layer having a thickness of 50 nm is formed on the first electrode by using copper phthalocyanine (CuPc), which is a hole injection material, and N, N-di (1-naphthyl), which is a hole transport material, is formed on the hole injection layer. -N, N'-diphenylbenzidine (NPD) was deposited to form a 10 nm thick hole transport layer.

As a light emitting material (red light emitting material) on the hole transport layer, carbazole biphenyl (CBP) and 10% tri (1-phenylquinoline) iridium Irq3 were formed to a thickness of 30 nm to form a light emitting layer, and then an intermediate layer on the light emitting layer. As an example, distyryl anthracene was formed to a thickness of 20 nm, tri (8-quinolinolato) aluminum (Alq3) was formed to a thickness of 20 nm on the intermediate layer to form an electron transport layer, and then an Al layer was formed as a second electrode. , An organic light emitting device was manufactured.

Example  2 (red element)

As a reflective first electrode, a 1300Å thick (aluminum and ITO) (SDI) substrate was cut into 50 mm x 50 mm x 0.7 mm and ultrasonically cleaned in isopropyl alcohol and pure water for 5 minutes and then for 30 minutes. UV and ozone cleaning were used.

A hole injection layer having a thickness of 50 nm was formed on the first electrode by using CuPc, which is a hole injection material, and then a hole transport layer having a thickness of 10 nm was formed by depositing NPD, a hole transport material, on the hole injection layer.

As a light emitting material (red light emitting material) on the hole transport layer, CBP and 10% Irq3 were formed to a thickness of 30 nm to form a light emitting layer, and then a biphenoxy-ratio (8-quinolinola) as a hole suppressing layer on the light emitting layer. Sat) aluminum (Balq) is formed to a thickness of 5nm, then distyryl anthracene 15nm thick as an intermediate layer on the hole suppression layer, Alq3 20nm thick on the intermediate layer to form an electron transport layer, An Al layer was formed as a 2nd electrode, and the organic light emitting element was produced.

Comparative example  1 (red element)

As a reflective first electrode, a 1300Å thick (aluminum and ITO) (SDI) substrate was cut into 50 mm x 50 mm x 0.7 mm and ultrasonically cleaned in isopropyl alcohol and pure water for 5 minutes and then for 30 minutes. UV and ozone cleaning were used.

A hole injection layer having a thickness of 60 nm was formed on the first electrode by using CuPc, which is a hole injection material, and NPD, which is a hole transporting material, was deposited on the hole injection layer to form a hole transport layer having a thickness of 30 nm.

As a light emitting material (red light emitting material) on the hole transport layer, CBP and 10% Irq3 were formed to a thickness of 30 nm to form a light emitting layer, and then Balq was formed as a hole suppression layer on the light emitting layer to a thickness of 5 nm, and the hole suppression was performed. An Alq3 was formed to a thickness of 20 nm on the layer to form an electron transport layer, and then an Al layer was formed as a second electrode to manufacture an organic light emitting device.

Evaluation example  1. Brightness and Current Efficiency of Red Devices

The current density, brightness, current efficiency, and power efficiency of the red organic light emitting diodes manufactured according to Examples 1, 2 and Comparative Example 1 are shown in FIGS. 3 to 6. 4 to 6, the organic light emitting diodes according to Examples 1 and 2 have higher luminance (FIG. 4) and higher current efficiency at a predetermined applied voltage than those of the organic light emitting diodes according to Comparative Example 1 (FIG. 5). It can be seen that power efficiency (FIG. 6) is shown.

As can be seen from FIG. 3, in the organic light emitting device according to the present invention, the case where the hole suppression layer is included does not include (Example 2), which is more excellent in current density than (Example 1). It can be seen that.

Example  3 (green device)

As a reflective first electrode, a 1300Å thick (aluminum and ITO) (SDI) substrate was cut into 50 mm x 50 mm x 0.7 mm and ultrasonically cleaned in isopropyl alcohol and pure water for 5 minutes and then for 30 minutes. UV and ozone cleaning were used.

A hole injection layer having a thickness of 50 nm was formed on the first electrode by using CuPc, which is a hole injection material, and then a hole transport layer having a thickness of 10 nm was formed by depositing NPD, a hole transport material, on the hole injection layer.

As a light emitting material (green light emitting material) on the hole transport layer, CBP and 5% tri (2-phenylpyridine) iridium (Irppy3) were formed to a thickness of 30 nm to form a light emitting layer, and then Balq as a hole suppression layer on the light emitting layer. 5 nm thick, distyryl anthracene 15 nm thick as an intermediate layer on the hole suppression layer, and Alq3 20 nm thick on the intermediate layer to form an electron transport layer, and then an Al layer as a second electrode. To form an organic light emitting device.

Comparative example  2 (green device)

As a reflective first electrode, a 1300Å thick (aluminum and ITO) (SDI) substrate was cut into 50 mm x 50 mm x 0.7 mm and ultrasonically cleaned in isopropyl alcohol and pure water for 5 minutes and then for 30 minutes. UV and ozone cleaning were used.

A hole injection layer having a thickness of 60 nm was formed on the first electrode by using CuPc, which is a hole injection material, and NPD, which is a hole transporting material, was deposited on the hole injection layer to form a hole transport layer having a thickness of 30 nm.

As a light emitting material (red light emitting material) on the hole transport layer, CBP and 5% Irppy3 were formed to a thickness of 30 nm to form a light emitting layer, and then Balq was formed as a hole suppression layer on the light emitting layer to a thickness of 5 nm, and the hole suppression was performed. An Alq3 was formed to a thickness of 20 nm on the layer to form an electron transport layer, and then an Al layer was formed as a second electrode to manufacture an organic light emitting device.

Evaluation example  2. Luminance and Current Efficiency of Green Devices

Current efficiency and power efficiency of the green organic light emitting diodes manufactured according to Example 3 and Comparative Example 2 are shown in FIGS. 5 and 6. 5 and 6, it can be seen that the organic light emitting diode according to Example 3 exhibits higher current efficiency (FIG. 6) and power efficiency (FIG. 7) at a predetermined applied voltage than the organic light emitting diode according to Comparative Example 2. have.

According to the present invention, it is possible to provide an organic light emitting device having increased efficiency and luminance and a low driving voltage and a flat panel display device having the same.

Claims (8)

A first electrode; Second electrode; And a light emitting layer between the first electrode and the second electrode, the organic light emitting device comprising a hole suppression layer and an electron transport layer between the light emitting layer and the second electrode, and between the hole suppression layer and the electron transport layer. An intermediate layer comprising a charge transfer control material in the organic light emitting device. delete delete The method of claim 1, wherein the charge transfer control material is at least one material selected from the group consisting of distyrylanthracene derivatives, distyryltetracene derivatives and diphenylvinyl derivatives. An organic light emitting device characterized in that. The organic light emitting device of claim 1, wherein the charge mobility of the intermediate layer including the charge mobility controlling material is lower than that of the electron transport layer and the hole suppression layer. The organic light emitting device of claim 1, wherein the charge transfer control material has electron transfer characteristics rather than hole transfer characteristics. The organic light emitting device of claim 1, wherein the intermediate layer including the charge transfer control material is 50 kPa to 150 kPa. A flat panel display comprising the organic light emitting device according to any one of claims 1 and 4 to 7, wherein a pixel electrode of the organic light emitting device is electrically connected to a source electrode or a drain electrode of the thin film transistor. Device.

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