KR20050119894A - Organic electro luminescence display device - Google Patents

Abstract

The present invention is to improve the outdoor visibility, the display unit having a plurality of pixels interposed between the first and second substrates and the first and second substrates opposed to each other, and partitions each pixel in the display unit And an insulating layer provided to absorb external light, and an antireflection member provided on the outside of at least one of the first and second substrates to absorb external light. will be.

Description

Organic electroluminescence display device

The present invention relates to an organic light emitting display device. More particularly, the present invention relates to an organic light emitting display device having improved outdoor visibility.

Electroluminescent display devices are attracting attention as next-generation display devices because of their advantages such as wide viewing angle, excellent contrast, and fast response speed. The electroluminescent display is classified into an inorganic electroluminescent display and an organic electroluminescent device according to the material forming the light emitting layer.

The inorganic electroluminescent display was originally commercialized as a green light emitting display, but similarly to a plasma display, it is an AC bias drive and requires several hundred volts to drive. In addition, since the material for emitting light is an inorganic material, it is difficult to control the light emission wavelength due to the molecular design and colorization of the image is difficult.

 In addition, the organic electroluminescent display is a self-luminous display that electrically excites fluorescent organic compounds to emit light, which can be driven at a low voltage, is easy to thin, and is problematic in liquid crystal display devices such as wide viewing angle and fast response speed. It is attracting attention as the next generation display that can solve the fault

Unlike the reflective LCD, the organic light emitting display device is a self-luminous device, and thus, the visibility of the screen is poor when the screen is viewed outdoors. That is, when the reflected light on the screen is increased by strong external light outdoors, and the reflected light approaches the intensity of the emitted light, the contrast is greatly reduced and the visibility is inferior.

In order to prevent the reduction of contrast, conventionally, a method of using a black matrix for attaching a polarizing plate to the surface of a substrate to block reflection of external light or for blacking non-emitting portions between each light emitting pixel for replacement of the polarizing plate. This was used a lot.

However, the use of these black matrices and polarizing plates has no great effect on contrast improvement when viewing the screen outdoors at midday. This is because the brighter the outdoor light, the greater the intensity of some reflected light in the display unit.

The present invention has been made to solve the above problems, and an object thereof is to provide an organic light emitting display device having improved outdoor visibility.

In order to achieve the above object, the present invention,

First and second substrates opposed to each other;

A display unit interposed between the first and second substrates and having a plurality of pixels;

An insulating layer partitioning each pixel in the display unit and absorbing external light; And

And an anti-reflection member disposed outside at least one of the first substrate and the second substrate and absorbing external light.

The insulating layer may be provided such that the first component, which is a transparent material, and the second component, which is a metal material, have a predetermined concentration gradient.

The first component is composed of a transparent insulating material such as SiOx (x≥1), SiNx (x≥1), MgF2, CaF2, Al2O3, SnO2, Indium tin Oxide (ITO), Indium Zinc Oxide (IZO), ZnO It may be provided with at least one transparent material selected from at least one of the group consisting of a transparent conductive material, such as In2O3.

The second component may be provided with at least one metal material selected from the group consisting of Fe, Co, V, Ti, Al, Ag, Si, Ge, Y, Zn, Zr, W, Ta, Cu, Pt.

The insulating layer may include a first thin film made of CrOx (x ≧ 1) and a second thin film made of Cr.

The anti-reflection member may be a circular polarizing film.

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

1 is a cross-sectional view of an organic light emitting display device according to an exemplary embodiment of the present invention, and includes a first substrate 1 and a second substrate 2 facing each other, and the first substrate 1 and The display unit 3 having a plurality of pixels is provided between the second substrates 2.

The first substrate 1 and the second substrate 2 are joined by the sealant 21 to seal the display portion 3.

The display unit 3 includes an insulating layer 4 partitioning each pixel and absorbing external light, and an antireflection member 5 absorbing external light on an outer surface of the first substrate 1 on which an image is implemented. ) Is provided. As the anti-reflection member 5, a circular polarizing film may be used.

On the other hand, the display unit 3 may be applied to any of PM type Passive martix organic light emitting display (PMOLED) and AM type of Active martix organic light emitting display (AMOLED). 2 illustrates an example of an PM type organic light emitting display, and FIG. 3 illustrates an example of an AM type organic light emitting display. This will be described in more detail as follows.

First, in the organic light emitting display of the PM type according to FIG. 2, the first electrode 31 which functions as an anode electrode on the first substrate 1 may have a predetermined pattern, for example, a stripe pattern or a predetermined pattern. And an insulating layer 4 is formed between the first electrodes 31.

An organic layer 32 including a light emitting layer is formed on the first electrode 31. A second electrode 33 serving as a cathode electrode is formed on the organic film 32 in a predetermined pattern. Although not shown in the figure, a cathode separator is formed of an insulator, and the cathode separator enables patterning of the second electrode 33. The polarity of the first electrode 31 and the second electrode 33 as described above may be opposite to each other.

When the image is a rear emitting type implemented toward the first substrate 1, the first electrode 31 may be formed as a transparent electrode, and the second electrode 33 may be formed as a reflective electrode. Can be. In the case of a front emitting type in which an image is embodied toward the second substrate 2, the first electrode 31 may be formed as a reflective electrode, and the second electrode 33 may be a transmissive electrode. Can be formed. In the embodiment according to FIG. 1, since the image is a back emission type in which the image is embodied toward the first substrate 1, the first electrode 31 is formed of a transparent electrode, and the second electrode 33 is formed of a reflective electrode. .

As the organic layer 32 including the light emitting layer, a low molecular or polymer organic layer may be used. When the low molecular organic layer is used, a hole injection layer (HIL), a hole transport layer (HTL), and an organic light emitting layer (EML) may be used. : Emission Layer (EIL), Electron Injection Layer (EIL), Electron Transport Layer (ETL), etc. may be formed by stacking in a single or complex structure, and usable organic materials are copper phthalocyanine (CuPc: copper phthalocyanine), N, N-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine (N, N'-Di (naphthalene-1-yl) -N, N'-diphenyl-benzidine: NPB), tris-8-hydroxyquinoline aluminum (Alq3), and the like can be variously applied. These low molecular weight organic films are formed by the vacuum deposition method.

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.

In the organic layer 33, at least the light emitting layer is patterned for each pixel of red (R), green (G), and blue (B) color to realize a full color.

In the display unit 3, as the anode and cathode voltages are respectively applied to the first electrode 31 and the second electrode 33, holes injected from the first electrode are moved to the emission layer, and electrons are transferred to the second layer. It is injected from the electrode into the light emitting layer, and electrons and holes recombine in this light emitting layer to generate excitons, and as the excitons change from the excited state to the ground state, the fluorescent molecules of the light emitting layer emit light to form an image. In the case of a full color organic light emitting display device, a full color is realized by including pixels emitting three colors of red (R), green (G), and blue (B).

On the other hand, in the AM type organic electroluminescent display according to FIG. 3, each pixel includes a TFT 12 and a capacitor 13. The number of TFTs and capacitors is not necessarily limited to the numbers shown in the figures, and of course, a larger number of thin film transistors and capacitors may be provided depending on the design of the desired device.

As shown in FIG. 3, a buffer layer 11 is formed on the first substrate 1, and a TFT 12 and a capacitor 13 are provided on the buffer layer 11.

The TFT 12 has a semiconductor active layer 14 formed on the buffer layer 11, a gate insulating film 15 formed on the semiconductor active layer 14, and a gate electrode 16 on the gate insulating film 15. .

The semiconductor active layer 14 may be formed of an amorphous silicon thin film or a polycrystalline silicon thin film, but is not limited thereto. This semiconductor active layer has source and drain regions doped with N-type or P-type impurities at a high concentration.

The gate insulating film 15 is provided on the semiconductor active layer 14 by SiO _{2 or the} like, and the gate electrode 16 is formed as a conductive film on a predetermined region above the gate insulating film 15. The gate electrode 16 is connected to the first electrode 13a of the capacitor 13 to supply a TFT on / off signal and is formed on the channel region of the semiconductor active layer 14.

An interlayer insulating film 17 is formed on the gate electrode 16, and the source / drain electrodes 18 are formed to contact the source / drain regions of the semiconductor active layer 14 through contact holes. One of the source / drain electrodes 18 is connected to the second electrode 13b of the capacitor 13.

A passivation film 19 made of an insulator is formed on the source / drain electrode 18, and a first electrode 31 of the EL element connected to the drain electrode by a contact hole is formed on the passivation film 19. do.

An insulating layer 4 is formed on the first electrode 31, and a predetermined opening 41 is formed in the insulating layer 4, and then the organic film 32 including a light emitting layer is formed in the opening 41. ) And the second electrode 33 are sequentially formed.

The first electrode 31, the second electrode 33, and the organic film 32 are as described above.

In the display unit 3 of the PM and AM structures as described above, the insulating layer 4 is provided to absorb external light.

According to a preferred embodiment of the present invention, the insulating layer 4 is opposite to the first component of the transparent material from the first substrate 1 and the second component of the metal material as shown in FIG. 4. It may be formed sequentially to have a concentration gradient to be. That is, the content of the first component decreases as the distance from the first substrate 1 decreases, and the content of the second component increases.

In this case, the first component is made of a transparent insulating material such as SiOx (x≥1), SiNx (x≥1), MgF ₂ , CaF ₂ , Al ₂ O ₃ , SnO ₂ , and Indium tin Oxide (ITO). , IZO (Indium Zinc Oxide), ZnO, In ₂ O ₃ It may be provided with at least one transparent material selected from at least one of the group consisting of a transparent conductive material, the second component is Fe, Co It may be provided with at least one metal material selected from the group consisting of, V, Ti, Al, Ag, Si, Ge, Y, Zn, Zr, W, Ta, Cu, Pt.

The insulating layer 4 formed as described above has a black color as a whole. Therefore, in the case of the bottom emission type organic electroluminescent display in which light is emitted in the direction of the first substrate 1, the insulating layer 4 is an external light absorbing layer that absorbs external light from the outside of the second substrate 3, that is, In addition, it can function as a black matrix. In addition to the insulating layer 4, when applied to the AM type, the second electrode provided with the metal material may provide conductivity to the second electrode, thereby preventing a voltage drop.

On the other hand, the insulating layer 4 as described above may be formed by other methods, that is, provided with CrOx (x ≧ 1) from the first substrate 1 toward the second electrode 33. The first thin film and the second thin film made of Cr may be sequentially formed and a graphite black matrix may be used.

In the present invention, in addition to the insulating layer 4 capable of absorbing external light between the pixels, the anti-reflection member 5 as described above is provided on the outer surface of the first substrate 1 on which the image is implemented. By forming a, it is possible to minimize the reflection of external light.

Table 1 compares the reflectance and contrast of the embodiment of the present invention according to FIG. 3 and the comparative examples.

 reflectivity Contrast Comparative Example 1 0.28% 1.4 Comparative Example 2 1.28% 1.1 Comparative Example 3 0.24% 1.4 Example 0.04% 3.5

Comparative Example 1 shows a case in which only a circular polarizing film is attached to an outer surface of a substrate on which an image is implemented, and Comparative Example 2 shows a case in which only a black matrix is formed on a non-light emitting part of a pixel. Comparative Example 3 shows a case where a black matrix is formed on a non-light emitting portion of each pixel, and an external light absorbing electrode is applied to the second electrode instead of the reflective electrode.

The embodiment illustrates a case in which an insulating layer, which is a black matrix, is formed on a non-light emitting portion of each pixel, and a circular polarizing film is attached to an outer surface of a first substrate on which an image is implemented.

In the above experiments, the contrast is to evaluate the visibility under very bright outdoor light of 100,000 lux, in the case of the embodiment according to the present invention, it can be seen that exhibits excellent contrast properties compared to the comparative examples.

As shown in FIG. 5, the present invention can be equally applied to the case where an image is implemented in the direction of the second substrate 2, in which case the antireflection member 5 is formed on the outer surface of the second substrate 2. Can be attached.

According to the organic light emitting display device of the present invention made as described above, even in outdoor light, the contrast can be improved to improve the outdoor visibility.

Although the present invention has been described with reference to one embodiment shown in the accompanying 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. Could be. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

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

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

3 is a partial cross-sectional view showing an example of an AM type organic light emitting display device according to another embodiment of the present invention;

4 is a view showing a concentration gradient between a conductive material and a dielectric material forming an insulating layer;

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

5 is a cross-sectional view of an organic light emitting display device according to another exemplary embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

1: first substrate 2: second substrate

3: display part 4: functional thin film

5: antireflection member 21: sealant

Claims (6)

First and second substrates opposed to each other; A display unit interposed between the first and second substrates and having a plurality of pixels; An insulating layer partitioning each pixel in the display unit and absorbing external light; And And an antireflection member disposed outside at least one of the first substrate and the second substrate and absorbing external light. The method of claim 1, And the insulating layer is provided such that the first component which is a transparent material and the second component which is a metal material have a predetermined concentration gradient. The method of claim 2, The first component is composed of a transparent insulating material such as SiOx (x≥1), SiNx (x≥1), MgF2, CaF2, Al2O3, SnO2, Indium tin Oxide (ITO), Indium Zinc Oxide (IZO), ZnO And at least one transparent material selected from the group consisting of a transparent conductive material such as In 2 O 3. The method of claim 2, The second component is provided with at least one metal material selected from the group consisting of Fe, Co, V, Ti, Al, Ag, Si, Ge, Y, Zn, Zr, W, Ta, Cu, Pt Organic electroluminescent display. The method of claim 1, And the insulating layer comprises a first thin film made of CrOx (x ≧ 1) and a second thin film made of Cr. The method according to any one of claims 1 to 5, And the anti-reflection member is a circular polarizing film.