KR100683694B1 - Organic light emitting device - Google Patents

Abstract

The present invention discloses an organic light emitting display device capable of improving luminous efficiency and lifetime by forming a regular wall layer on a phosphorescent red light emitting layer, a fluorescent green light emitting layer, and a blue light emitting layer as a common layer.

An organic light emitting display device comprising a plurality of pixels each having R, G, and B pixels, comprising: lower electrodes of R, G, and B pixels formed on a substrate; A first carrier transport layer formed on the substrate; R, G and B light emitting layers respectively formed on the first carrier transport layer corresponding to the lower electrodes of the R, G and B pixels; A second carrier transport layer formed on the substrate; And a cathode electrode formed on the substrate, wherein the R light emitting layer includes a phosphorescent material, and the G light emitting layer and the B light emitting layer include a fluorescent light emitting material, between the R, G, B light emitting layer, and the second carrier transport layer. A common wall layer is further provided as a common layer. The factory wall layer includes Balq.

Description

Organic light emitting device

1 is a cross-sectional view of a conventional organic light emitting display device;

2 is a cross-sectional view of an organic light emitting display device according to an embodiment of the present invention;

Explanation of symbols on the main parts of the drawings

210: substrate 230, 250: carrier transport layer

221, 223, 225 R, G, B anode electrodes

241, 243, 245: R, G, B light emitting layer

255: factory wall layer 260: cathode electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device, and more particularly, to a method of manufacturing an organic light emitting display device having a regular wall layer as a common layer on a phosphorescent red light emitting layer and a fluorescent green and blue light emitting layer.

In general, an organic light emitting display (OLED) has a structure in which an organic layer is formed on an anode electrode, which is a lower electrode, and a cathode electrode is formed thereon as an upper electrode. The organic layer includes a light emitting layer and a carrier transport layer for emitting light of R, G, and B colors. The carrier transport layer includes a hole injection layer and a hole transport layer formed between the light emitting layer and the anode electrode, and an electron transport layer and the electron injection layer formed between the light emitting layer and the cathode electrode.

A material having a property of a p-type semiconductor is used for the hole transport layer and a material having a property of an n-type semiconductor is used for the electron transport layer. The light emitting layer may include a phosphor that emits phosphorescence or a phosphor that emits fluorescence according to a light emitting mechanism.

1 illustrates a cross-sectional structure of a conventional organic light emitting display device.

Referring to FIG. 1, in the conventional organic light emitting display device, anode electrodes 121, 123, and 125 of R, G, and B pixels are formed on a substrate 110, and a cathode electrode 160 is disposed thereon. ) Is formed. Between the R, G, and B anode electrodes 121, 123, 125 and the cathode electrode 160, R corresponds to the R, G, and B anode electrodes 121, 123, and 125. , G, B light emitting layers 141, 143, and 145 are formed, respectively. The R, G, and B light emitting layers 141, 143, and 145 include fluorescent materials.

The first carrier transport layer 130 is formed as a common layer between the R, G, and B anode electrodes 121, 123, and 125 and the R, G, and B light emitting layers 141, 143, and 145. Is formed. The first carrier transport layer 130 is selected from a hole injection layer and a hole transport layer.

A second carrier transport layer 150 is formed as a common layer between the R, G, and B light emitting layers 141, 143, and 145 and the cathode electrode 160. The second carrier transport layer 150 is selected from an electron transport layer and an electron injection layer.

In the organic light emitting device as described above, when a predetermined bias voltage is applied to the anode electrode and the cathode electrode, holes are transferred from the anode electrode to the light emitting layer, electrons are transferred from the cathode electrode to the light emitting layer, and holes and electrons transferred to the light emitting layer. Are recombined to emit R, G, and B colors.

In the conventional organic light emitting device, R, G, and B light emitting layers 141, 143, and 145 all include fluorescent materials, and R, G, and B, which emit light of different colors of R, G, and B, The organic fluorescent materials of the light emitting layer B have different luminous efficiency. Therefore, when implementing a full color organic light emitting display device using organic fluorescent materials having different luminous efficiencies, when the R, G, and B light emitting layers are driven at the same current level, some of the light emitting layers of the R, G, and B light emitting layers The light emitting efficiency is low with respect to the current level while the remaining light emitting layer has a relatively high light emission efficiency with respect to the current level.

Therefore, in a full color organic light emitting display device, in order to achieve a white balance, a driving current suitable for a light emitting layer having a relatively low luminous efficiency should be driven. That is, by driving the light emitting layer by increasing the driving current to increase the light emitting efficiency of the light emitting layer of low luminous efficiency to achieve a white balance. However, when driving the light emitting layer with a high driving current to match white, there is a problem that the power consumption increases, and thus the life is reduced.

In Korean Laid-Open Patent Publication No. 2003-0020034, in order to solve the problem that power consumption increases when driving current is increased to adjust the white balance, the light emitting layer having the low luminous efficiency among R, G, and B light emitting layers is composed of phosphorescent material. In addition, an organic light emitting diode having a relatively high luminous efficiency as a light emitting layer composed of a fluorescent material has been disclosed.

In addition, since the light emitting layer made of phosphor material has a smaller recombination rate between holes and electrons than the light emitting layer made of phosphor material, it is preferable that the holes stay in the light emitting layer for a long time. A blocking layer was formed to allow the holes to stay longer in the light emitting layer.

On the other hand, Japanese Patent Application Laid-Open No. 2004-14155 proposes an organic electroluminescent device which can obtain high efficiency without deteriorating color purity of white light emission using phosphorescent material. The Japanese patent discloses that in an organic light emitting device for white light emitting, wherein the light emitting layer includes at least two kinds of light emitting core materials, the blue light material is a phosphorescent material, and the green light material and the red light material are fluorescent light emitting materials.

The present invention is to solve the problems of the prior art as described above, by forming a hole suppression layer as a common layer on the G light emitting layer and the B light emitting layer containing the R light emitting layer containing the phosphor and the fluorescent material and luminous efficiency and lifetime An object of the present invention is to provide an organic light emitting display device which can improve the efficiency.

In order to achieve the above object, the present invention provides an organic light emitting display device including a plurality of pixels each having R, G, and B pixels, comprising: lower electrodes of R, G, and B pixels respectively formed on a substrate; A first carrier transport layer formed on the substrate; R, G and B light emitting layers respectively formed on the first carrier transport layer corresponding to the lower electrodes of the R, G and B pixels; A second carrier transport layer formed on the substrate; And a cathode electrode formed on the substrate, wherein the R light emitting layer includes a phosphorescent material, and the G light emitting layer and the B light emitting layer include a fluorescent light emitting material, between the R, G, B light emitting layer, and the second carrier transport layer. An organic light emitting display device further comprising a factory wall layer as a common layer is provided.

 The first carrier transport layer is selected from a hole injection layer and a hole transport layer, and the second carrier transport layer includes an electron transport layer.

The R light emitting layer is a phosphorescent light emitting material including CBP and BTP, a G light emitting layer is a fluorescent light emitting material containing Alq3 and C545T, B light emitting layer is a fluorescent light emitting material containing DPVBi and perylene.

The factory wall layer includes Balq.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

2 is a cross-sectional view of an organic light emitting display device according to an exemplary embodiment of the present invention. FIG. 2 is a schematic view illustrating the organic light emitting display device in a full color organic light emitting display device.

Referring to FIG. 2, in the organic light emitting display device, a plurality of pixels are arranged on a substrate 210, and each pixel includes R, G, and B pixels. R, G, and B pixels constituting each pixel are arranged in the R, G, and B pixel areas 201, 203, and 205 of the substrate 210, respectively.

On the pixel areas 201, 203, and 205 of the substrate 210, anode electrodes 221, 223, and 225, which are pixel electrodes of R, G, and B pixels, are formed, respectively. The anode electrodes 221, 223, and 225 include a transparent electrode in the back light emitting structure in which light emitted from the light emitting layer is emitted toward the substrate, and a reflective film in the front light emitting structure in the opposite direction to the substrate. It includes a transparent electrode. In addition, the anode electrodes 221, 223, and 225 include transparent electrodes in a double-sided light emitting structure in which light emitted from the light emitting layer is simultaneously emitted in a direction opposite to the substrate.

The first carrier transport layer 230 is formed on the front surface of the substrate. The carrier transport layer 230 serves as a common layer for the R, G, and B pixels, and the first carrier transport layer 230 includes a carrier transport layer selected from a hole injection layer and a hole transport layer.

The hole transport layer includes copper phthalocyanine (CuPC). The hole injection layer is N, N-di-naphthalen-1-yl-N, N'-diphenyl-benzidine (NPB, N4, N4-di-naphthalene-1-y1-N4, N4'-diphenyl-benzidine) It includes.

R, G, and B light emitting layers 241, 243, and 245 of R, G, and B pixels are formed on the first carrier transport layer 230, respectively. The R, G, and B light emitting layers 241, 243, and 245 are R, G, and B pixel electrodes 221 of the R, G, and B pixel regions 201, 203, and 205, respectively. It is formed corresponding to 223 and 235.

The R light emitting layer 241 includes a phosphorescent material, and 4,4'-N, N'-dicarbazole-biphenyl (CBP, 4,4'-N, N'-dicarbazole-biphenyl) as a host material. Dopant material includes BTP. The G emission layer 243 includes a fluorescent light emitting material, and includes tris-8-hydroxyquinoline aluminum (Alq3) as a host material and C545T as a dopant material. The B emission layer 245 includes a fluorescent material, and includes DPVBi as a host and perylene as a dopant.

The R, G, and B light emitting layers 241, 243, and 245 form an R light emitting layer 241 including a phosphorescent material, and then a G light emitting layer 243 and a B light emitting layer 245 including a fluorescent light emitting material. ) Or the G light emitting layer 243 and the B light emitting layer 245 including the fluorescent light emitting material, respectively, and then the R light emitting layer 241 including the phosphorescent material.

In addition, the R, G, and B light emitting layers 241, 243, and 245 may be formed using a laser transfer method, an inkjet method, a spin coating method, a vapor deposition method, and the like. In addition to the light emitting material, various phosphorescent materials and fluorescent light emitting materials can be used.

Hole blocking layers (HBLs) 255 are formed on the R, G, and B light emitting layers 241, 243, and 245. The regular wall layer 255 serves as a common layer for the R, G, and B pixels as a carrier transport layer. The refined wall layer 255 contains bis-2-methyl-8-quinolinolatopara- pentylphenalato aluminum (III) (Balq), bis-2-methyl-8-quinolinolato para-phenylphenolato aluminum (III), Balq. do.

The second carrier transport layer 250 is formed on the factory wall layer 255. The second carrier transport layer 250 includes an electron transport layer. The electron transport layer includes Alq3.

The cathode electrode 260 is formed on the second carrier transport layer 250 as an upper electrode. The cathode electrode 260 includes an opaque electrode in the back light emitting structure in which light emitted from the light emitting layer is emitted toward the substrate, and a transparent electrode in the front light emitting structure in the opposite direction to the substrate. In addition, the cathode electrode 260 includes a transparent electrode in the double-sided light emitting structure in which the light emitted from the light emitting layer is simultaneously emitted in the opposite direction to the substrate.

Although not shown in the drawing, when the organic light emitting display device of the present invention is an active matrix type, a driving element for driving an anode electrode, which is a lower electrode of the R, G, and B pixels, is provided on the substrate. The driving device includes a thin film transistor and a capacitor.

As described above, the hole suppression layer 255 is formed not only on the R light emitting layer 231 including the phosphorescent material, but also on the G light emitting layer and the B light emitting layer including the fluorescent light emitting material, and on the R light emitting layer. When comparing the characteristics in the case of forming as follows.

For example, when the G light emitting layer has no hole suppression layer on the G light emitting layer containing a fluorescent light emitting material, the luminance is 19 cd / A and the lifetime is 5,000 hours. On the other hand, when the regular wall layer is formed on the G light emitting layer containing the fluorescent light emitting material, the luminance is 21 cd / A and the lifetime is 6000 hours or more. Accordingly, it can be seen that when the regular wall layer is formed on the G light emitting layer including the fluorescent light emitting material, the luminance is increased and the service life is longer than that of the hole suppressing layer on the G light emitting layer.

According to an embodiment of the present invention, as the anode electrode and the cathode electrode are composed of a transparent electrode or a reflective electrode, a back light emitting structure in which light emitted from the light emitting layer is emitted toward the substrate, a front light emitting structure emitting in the opposite direction of the substrate, or It is applicable to both the substrate and the double-sided light emitting structure which are simultaneously emitted in the opposite direction of the substrate.

In an embodiment of the present invention, in an active matrix organic light emitting display device, a hole blocking layer is formed as a common layer on an R light emitting layer including a phosphorescent material and a G light emitting layer including a fluorescent light emitting material and a B light emitting layer, thereby providing high efficiency and long life. Although an example of obtaining a device is illustrated, the present invention is also applicable to a passive matrix organic light emitting display device in which an anode electrode and a cathode electrode in a stripe form are arranged to cross each other.

In addition, the present invention is applicable to both a high molecular organic EL device or a low molecular organic EL device according to the organic material constituting the hole transport layer, the light emitting layer and the electron transport layer.

According to the full-color organic light emitting display device according to the embodiment of the present invention as described above, the R light emitting layer comprises a phosphorescent material, the G light emitting layer and the B light emitting layer comprises a fluorescent light emitting material, and as a common layer on the light emitting layer By forming the hole suppression layer, there is an advantage that the luminance can be increased, thereby extending the life of the device.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (5)

In an organic light emitting display device including a plurality of pixels each having R, G, and B pixels, Lower electrodes of R, G, and B pixels respectively formed on the substrate; A first carrier transport layer formed on the substrate; R, G and B light emitting layers respectively formed on the first carrier transport layer corresponding to the lower electrodes of the R, G and B pixels; A second carrier transport layer formed on the substrate; It includes a cathode electrode formed on the substrate, The R light emitting layer includes a phosphorescent material, The G light emitting layer and the B light emitting layer includes a fluorescent light emitting material, An organic light emitting display device further comprising a factory wall layer as a common layer between the R, G, and B light emitting layers and the second carrier transport layer. The organic light emitting display device of claim 1, wherein the first carrier transport layer comprises a carrier transport layer selected from a hole injection layer and a hole transport layer. The organic light emitting display device of claim 1, wherein the second carrier transport layer comprises an electron transport layer. According to claim 1, wherein the R light emitting layer is a phosphorescent light emitting material containing CBP and BTP, G light emitting layer is a fluorescent light emitting material containing Alq3 and C545T, B light emitting layer is a fluorescent light emitting material containing DPVBi and perylene An organic light emitting display device. The organic light emitting display device according to claim 1, wherein the factory wall layer comprises Balq.

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