KR100768230B1 - Organic electro luminescence display device - Google Patents

Abstract

An organic electro luminescence display device is provided to reduce a driving voltage by independently forming auxiliary layers with high electric charge mobility at each pixel in a certain area of a common layer with the low electric charge mobility. An organic electro luminescence display device includes a substrate, an anode electrode, a cathode electrode, an emission layer, first and second common layers(16,18), and an auxiliary layer(19). The emission layer emits red, green and blue light between the anode electrode and the cathode electrode. The common layers(16,18) are formed on the whole substrate(100) and the auxiliary layer(19) is made of material having higher electric charge mobility than that of the second common layer(18). The auxiliary layer(19) is formed to correspond to the red and green emission pixels.

Description

Organic electroluminescence display device

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

FIG. 2 is a partially enlarged view of A, B, and C of FIG. 1.

3 is a partially enlarged view of an organic light emitting diode display according to a second exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10 substrate 12 pixel electrode

14: insulating film (pixel defining layer) 16: hole injection layer (first common layer)

18: hole transport layer (second common layer) 20: hole blocking layer (hole suppression layer)

22: electron transport layer 24: counter electrode

100: red organic light emitting layer 200: green organic light emitting layer

300: blue organic light emitting layer

The present invention relates to an organic light emitting display device, and more particularly, to form an auxiliary layer having a high charge mobility in a common layer having a low charge mobility, thereby preventing crosstalk and lowering a driving voltage of the device. The present invention relates to an organic light emitting display device.

In general, the organic light emitting device is composed of various layers such as a first electrode and a second electrode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer. The organic light emitting device is divided into a polymer and a low molecule according to the material used.In the case of a low molecular organic EL device, each layer is introduced by vacuum deposition, and in the case of a polymer organic EL device, a process such as inkjet printing is used. A light emitting device can be made.

According to the functions of each layer, a low molecular organic light emitting device laminates a plurality of organic layers such as a hole injection layer, a hole transport layer, a light emitting layer, a hole suppression layer, and an electron injection layer by a deposition process, and finally deposits a cathode electrode to complete the device. .

When manufacturing a low molecular weight device using a conventional process, the hole injection layer and the hole transport layer are deposited as a common layer, and R, G, and B are independently deposited and patterned, and then a hole suppression layer and an electron injection layer are sequentially deposited as a common layer. Deposit a cathode.

In the case of a low molecular organic EL device, each layer may be introduced by vacuum deposition to make a fluorescent and / or phosphorescent element, but when a full color element is made, each layer is deposited using a mask. Patents for this include US Pat. Nos. 6,310,360, 6,303,238, 6,097,147, and the like.

On the other hand, when configuring a full color organic light emitting display device, a common layer structure is generally used as described above. However, in order to improve efficiency and color characteristics of the device, a common layer having a different thickness may be used. In particular, in the element using the resonance effect, a common layer structure different in color is often used.

In this case, since the patterning of the common layer should be performed using a mask, the use of a material having a high mobility of charge as a material of the common layer has the advantage of lowering the driving voltage of the device.

However, when the entire common layer is formed of a material having high mobility of charges, crosstalk due to leakage of current between each pixel increases, which is a problem.

The present invention has been made to solve the above problems and other problems, cross-talk prevention by using a common layer made of a material having a low charge mobility and an auxiliary layer made of a material having a high charge mobility An object of the present invention is to provide an organic light emitting display device having a low driving voltage.

The present invention is formed between a substrate, a first electrode and a second electrode formed on the substrate, and the first electrode and the second electrode, and defines each pixel and defines red (R), green (G), and blue ( B) an organic light emitting layer that is patterned and formed over the entire surface of the substrate between the organic light emitting layer and the first electrode or between the organic light emitting layer and the second electrode, at least one common layer having low charge mobility; The organic light emitting diode display may include a plurality of auxiliary layers that are formed to correspond to pixels displaying at least one of the red, green, and blue colors in a portion of the common layer, and have a higher charge mobility than the common layer. To provide.

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

1 to 2 are views for explaining a first embodiment of the present invention, Figure 1 is a cross-sectional view showing the structure of an organic light emitting display device according to the first embodiment. FIG. 2 is an enlarged view illustrating portions A, B, and C of FIG. 1 in an enlarged manner.

The organic light emitting diode OLED according to the first exemplary embodiment of the present invention displays predetermined image information by emitting red (R), green (G), and blue (B) colors according to the flow of current. A pixel electrode (which may correspond to the first electrode of the present invention) 12, an opposite electrode (which may correspond to the second electrode of the present invention) 24 provided to cover the entire pixel, and these pixel electrodes ( It consists of the organic film 15 arrange | positioned between 12 and the counter electrode 24, and light-emits.

The pixel electrode 12 and the counter electrode 24 are insulated from each other by the organic film 15.

Referring to FIG. 1, a pixel electrode 12, which is an electrode of an organic light emitting diode (OLED), is formed on a substrate 10, and a pixel definition layer (also referred to as an insulating layer) 14 is formed on the substrate 10. After the predetermined opening is formed in the pixel definition layer 14 to expose the pixel electrode 12, the organic layer 15 of the organic light emitting diode OLED is formed.

Although not shown in the drawings, the substrate 10 may further include a pixel circuit electrically connected to each pixel electrode 12, and each pixel circuit may include at least one TFT.

The organic layer 15 may be a low molecular or high molecular organic layer. When using a low molecular organic film, a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), a hole blocking layer (HBL), an electron transport layer (ETL) : Electron Transport Layer (EIL), Electron Injection Layer (EIL), etc. can be formed by stacking in single or complex structure. Usable organic materials are also copper phthalocyanine (CuPc), N, N-D (Naphthalen-1-yl) -N, N'-diphenyl-benzidine (N, N'-Di (naphthalene-1-yl) -N, N'-diphenyl-benzidine: NPB), tris-8-hydroxy Various applications are possible, including quinoline aluminum (tris-8-hydroxyquinoline aluminum) (Alq3). These low molecular weight organic films are formed by the vacuum deposition method. In this case, the hole injection layer, the hole transport layer, the electron transport layer, the electron injection layer, etc. may be commonly applied to red, green, and blue pixels as a common layer. Therefore, these common layers may be formed to cover the entire pixels, such as the counter electrode 24.

In the case of the polymer organic film, the structure may include a hole transporting layer (HTL) and a light emitting layer (EML). In this case, PEDOT is used as the hole transporting layer, and polyvinylvinylene (PPV) and polyfluorene are used as the light emitting layer. Polymer organic materials such as (Polyfluorene) are used and can be formed by screen printing or inkjet printing.

The organic layer as described above is not necessarily limited thereto, and various embodiments may be applied.

As an example of such an organic film, FIG. 1 shows a structure including a low molecular organic film having the hole injection layer as the first common layer 16 and the hole transport layer as the second common layer 18.

As a feature of the present invention, each of the common layers may be formed of a material having a low charge mobility, and an auxiliary layer having a high charge mobility may be included therein, which will be described in detail later with reference to FIG. 2. .

Meanwhile, in the first embodiment of the present invention as an organic light emitting display device capable of realizing a full color, as shown in FIG. 1, a light emitting layer emitting light for each color of red (100), green (200), and blue (300). (EML: Emission Layer) is formed. The emission layer may be formed for each color of R (100), G (200), and B (300) using vacuum deposition, spin coating, or laser thermal transfer. In the case of using the vacuum deposition method, the shadow mask may be used to pattern R, G, and B. In the case of using the laser thermal transfer method, the shadow mask may not be used because only a desired portion is transferred by laser scanning.

On the upper portion of the light emitting layer, a hole suppression layer 20 and / or an electron transporting layer 22 are applied as a common layer over the entire substrate. In addition, although not shown in the drawings, an electron injection layer may be further applied. The formation method and the constituent material are as described above.

Just note here. In the first embodiment, a structure including an auxiliary layer in a common layer, which is a feature of the present invention, is applied only to the hole injection layer or the hole transport layer. However, the structure includes the hole suppression layer 20, the electron transport layer 22, or Naturally applicable to the electron injection layer, etc., this also belongs to the scope of the present invention.

In the organic light emitting diode display according to the first exemplary embodiment as described above, the organic light emitting layer 15 is completed by laminating the hole suppression layer 20, the electron transport layer 22, and the hypothesized injection layer. The counter electrode 24 is stacked on the organic light emitting film 15.

The pixel electrode 12 and the counter electrode 24 will be described in detail. The pixel electrode 12 functions as an anode electrode, and the counter electrode 24 functions as a cathode electrode. The polarity of these pixel electrodes 12 and the counter electrode 24 may be reversed.

In the case of a bottom emission type in which an image is implemented in the direction of the substrate 10, the pixel electrode 12 may be a transparent electrode, and the opposite electrode 24 may be a reflective electrode. In this case, the pixel electrode 12 is formed of ITO, IZO, ZnO, In2O3 or the like having a high work function, and the counter electrode 24 is formed of a metal having a low work function, that is, Ag, Mg, Al, Pt, Pd, Au, or the like. , Ni, Nd, Ir, Cr, Li, Ca and the like.

In the case of a top emission type for implementing an image in the direction of the counter electrode 24, the pixel electrode 12 may be provided as a reflective electrode, and the counter electrode 24 may be provided as a transparent electrode. have. In the first embodiment, it is assumed that the present invention is applied to the front emission type. In FIG. 1, a black arrow indicates a direction in which an image is implemented. At this time, the reflective electrode serving as the pixel electrode 12 is formed of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, a compound thereof, and the like, and then thereon It may be formed by forming a high work function ITO, IZO, ZnO, In2O3 or the like. The transparent electrode serving as the counter electrode 24 is formed by depositing a metal having a small work function, that is, Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, or a compound thereof. After that, an auxiliary electrode layer or a bus electrode line may be formed thereon with a transparent conductive material such as ITO, IZO, ZnO, or In 2 O 3.

In the case of a double-sided emission type, both the pixel electrode 12 and the counter electrode 24 may be provided as transparent electrodes.

The pixel electrode 12 and the counter electrode 24 are not limited to those formed of the above-described materials, and may be formed of a conductive organic material or a conductive paste containing conductive particles such as Ag, Mg, and Cu. In the case of using such a conductive paste, it may be printed using an inkjet printing method, and after printing, may be baked to form an electrode.

Now, the structure of the common layer, which is one feature of the present invention, will be described in detail with reference to FIG. 2. FIG. 2 is an enlarged view of a lower portion of the light emitting layer in each pixel in FIG. 1. A is an enlarged view of the bottom of the red light emitting layer 100, B is the green light emitting layer 200, and C is the blue light emitting layer 300.

Referring to FIG. 2, in the first embodiment of the present invention, the first common layer 16 includes the hole injection layer described above, and the second common layer 18 includes the hole transport layer described above.

The first common layer 16 and the second common layer 18 are formed in common across the entire substrate 10. The first common layer 16 and the second common layer 18 are formed of a material having low charge mobility.

Meanwhile, an auxiliary layer 19 may be formed independently in each pixel in a portion of the second common layer 18. The auxiliary layer 19 is formed of a material having a higher charge mobility than the material forming the second common layer 18. The auxiliary layer 19 is formed differently for each color to improve efficiency and color characteristics of the device.

In the first embodiment, the auxiliary layer 19 is formed to correspond to the red (100) and green (200) organic emission layers, that is, to correspond to the red (100) and green (200) pixels. However, this is merely exemplary and in some cases, the pixel on which the auxiliary layer is formed may be a pixel displaying a different color.

By forming the auxiliary layer 19 as in the first embodiment, light emission of the organic light emitting layer of red (100) and green color (200) is made possible by the lower driving voltage. Since it is not formed, a higher driving voltage is required when the blue (300) pixel emits light than when the red (100) and green (200) pixels are driven. The above driving characteristics appear as a result of changing the color characteristics.

The auxiliary layer 19 is preferably formed independently for each pixel so that adjacent pixels are not connected by the auxiliary layer 19 when it is formed. This prevents crosstalk due to leakage of current between the pixels.

Referring now to Figure 3 will be described in detail a second embodiment of the present invention. 3 is a view showing the same region as that of FIG. 2, in which the second embodiment differs in part from the first embodiment in its structure. In the drawings, the same reference numerals refer to the same members. Hereinafter, the second embodiment will be described based on differences from the first embodiment.

In the second embodiment, two types of auxiliary layers are formed inside the second common layer 18 in the pixel in which the auxiliary layers are formed. One is an auxiliary layer formed by combining the first auxiliary layer 19b and the second auxiliary layer 19a, and the other is an auxiliary layer composed of only the second auxiliary layer 19a. Each of the auxiliary layers has a higher charge mobility than the common layer, but when the second auxiliary layer 19b and the second auxiliary layer 19a are compared with each other, the charge mobility of the second auxiliary layer is higher.

As illustrated in FIG. 3, the first auxiliary layer 19b is formed in a portion of the second common layer 18 corresponding to the red 100 organic emission layer. Below the green 200 organic emission layer, a first auxiliary layer 19b and a second auxiliary layer 19a are formed in a portion of the second common layer 18.

Both the first auxiliary layer 19a and the second auxiliary layer 19b are formed of a material having higher charge mobility than the second common layer 18. The first auxiliary layer 19a is formed of a material having a higher charge mobility between the first auxiliary layer 19a and the second auxiliary layer 19b.

One feature of the second embodiment of the present invention is that when there are two adjacent pixels and each pixel includes a second auxiliary layer 19a, the second auxiliary layer 19a of each pixel is arranged so as not to contact each other. to be. That is, in the second embodiment, the auxiliary layer formed under the green 200 organic light emitting layer has the second auxiliary layer 19a formed on the first auxiliary layer 19b, so that the second auxiliary layer 19a of the adjacent red 100 pixels is formed. Are not in direct contact with

The charge mobility of the pixel in which both the first auxiliary layer 19b and the second auxiliary layer 19a are formed is higher than when only the second auxiliary layer 19a is present. Of course, in the pixel 300 in which no auxiliary layer is formed, for example, in the blue 300 pixel, since the auxiliary layer is not formed inside the second common layer 18, the charge mobility among the pixels of each color is the highest. low.

As the auxiliary layers having different charge mobility for each color are formed differently, it is possible to finely adjust the efficiency and color characteristics of the device while lowering the driving voltage of the pixel.

How much auxiliary layer is used for which color pixel may be differently determined as necessary, and the second embodiment of the present invention shown in FIG. 3 may be regarded as an example.

According to the present invention as described above, since the auxiliary layer with high charge mobility is formed in each pixel independently in some regions of the common layer with low charge mobility, the cross between the pixels is reduced while lowering the driving voltage of the organic light emitting diode display. The torque can be prevented.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (7)

Board; First and second electrodes formed on the substrate; An organic emission layer formed between the first electrode and the second electrode and defining each pixel and formed in a pattern of red (R), green (G), and blue (B); One common layer formed over the entire surface of the substrate between the organic light emitting layer and the first electrode or between the organic light emitting layer and the second electrode; And A plurality of auxiliary layers formed to correspond to pixels displaying one of the red, green, and blue colors in a portion of the common layer, and having higher charge mobility than the common layer; An organic light emitting display device comprising a. The method of claim 1, And the auxiliary layers respectively corresponding to adjacent pixels among the pixels are independently formed by being blocked by the common layer. The method of claim 1, The organic light emitting diode display further comprises an insulating layer formed between the first electrodes. The method of claim 1, The common layer includes one of a hole injection layer and a hole transport layer. The method of claim 1, The common layer includes an electron injection layer, an electron transport layer, and a hole blocking layer. The method of claim 1, One of the auxiliary layers includes a first auxiliary layer having a higher charge mobility than the common layer and a second auxiliary layer having a higher charge mobility than the first auxiliary layer. The method of claim 6, The second auxiliary layers respectively corresponding to adjacent pixels are independently formed by being blocked by the common layer or the first auxiliary layer.

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