KR20150077855A - Organic light emitting display device using white organic light emitting element and color filter - Google Patents

Abstract

The present invention relates to an organic light emitting display device capable of improving light efficiency using a white organic light emitting element and a color filter. The organic light emitting display device includes: a thin film transistor substrate which includes first thin film transistors formed on a first substrate, and the white organic light emitting element between first electrodes and a second electrode which are respectively connected to each other; and a color filter substrate which faces the thin film transistor substrate. The color filter substrate includes: a second substrate which has concave parts formed in a position corresponding to the first electrodes; a high viscosity planarization layer formed on the second substrate; and color filter layers formed on the high viscosity planarization layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white organic light emitting diode (OLED)

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to an organic light emitting diode (OLED) display, and more particularly, to an OLED display capable of improving light efficiency using a white organic light emitting diode and a color filter.

2. Description of the Related Art Recently, various flat panel display devices capable of reducing weight and volume, which are disadvantages of cathode ray tubes (CRTs), have been developed. Such a flat panel display device includes a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP) And a light emitting device (Electroluminescence Device).

PDP has attracted attention as a display device that is most advantageous for large screen size but small size because of its simple structure and manufacturing process, but it has disadvantage of low luminous efficiency, low luminance and high power consumption. In addition, although the liquid crystal display device is one of the most widely used flat panel display devices, there is a problem that the viewing angle is narrow and the response speed is low. The electroluminescent device is roughly divided into an inorganic light emitting display device and an organic light emitting display device depending on the material of the light emitting layer. Of these organic electroluminescent display devices, self-emitting self-light emitting devices have a high response speed and a large luminous efficiency, luminance and viewing angle have.

In such an OLED display device, three pixels of red, green, and blue are used in a display driving mode. Recently, white OLEDs have been studied as one of the powerful ways to reduce power efficiency. And a color filter are bonded to each other.

However, in such an organic light emitting device, a structure such as a light waveguide is formed between the substrate and the organic light emitting device. As a result, a considerable amount of light can not be emitted to the outside due to total internal reflection of the light generated in the light emitting layer on the surface of the organic light emitting element, the electrode or the interface with the color filter layer, etc., there was.

In order to solve this problem, a method of increasing the light extraction efficiency by attaching a micro lens array or a light diffusion film to the outer surface of the display device has been proposed. However, according to this method, the improvement of the light efficiency is only about 1.6 times, and the limit is clear, and there is another problem that it is difficult to apply to the display device due to the color change and the interference color according to the viewing angle due to the diffraction phenomenon.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an organic light emitting diode display capable of improving light efficiency by using a white organic light emitting device and a color filter in order to solve the above problems.

According to an aspect of the present invention, there is provided an organic light emitting diode display comprising: a plurality of thin film transistors formed on a first substrate; a plurality of first electrodes connected to the plurality of thin film transistors; A thin film transistor substrate to be formed; And a color filter substrate disposed opposite to the thin film transistor substrate, wherein the color filter substrate includes a second substrate having a plurality of recesses formed at positions corresponding to the first electrodes, And a plurality of color filter layers formed on the high viscosity planarizing film.

In the above configuration, the high-viscosity flattening film has a refractive index in the range of 1.2 to 1.4.

Also, the high viscosity planarizing film may be formed of poly [4,5-difluoro-2,2-bis (trifluoromethyl) -1,3-dioxol-cetetrafluoroethylene] 2,2-bis (trifluoromethyl) -1,3-dioxole-co-tetrafluoroethylene]), poly (2,2,3,3,4,4,4-heptafluorobutyl acrylate) , 3,4,4,4-hexafluorobutyl acrylate), poly (2,2,2-trifluoromethylmethacrylate), poly (2,2,2-trifluoromethyl acrylate), poly And poly (1,1,1,3,3,3-hexafluorobutyl acrylate).

In addition, the plurality of color filter layers are formed corresponding to the concave portions of the second substrate.

The OLED display may further include a thin film transistor layer and a reflective layer formed between the first electrodes.

The plurality of first electrodes are respectively connected to the thin film transistors through contact holes formed in the reflective film.

In addition, neighboring first electrodes among the plurality of first electrodes may be separated by a bank.

According to the organic light emitting diode display according to the present invention, an air gap is formed by the concave portion formed at the position of the second substrate corresponding to the color filter layers, and a high viscosity planarizing film is formed on the air gap. The green color filter layer, and the blue color filter layer depending on the refractive index difference of the high-viscosity material layer and the high-viscosity material layer.

1 is a circuit diagram showing one pixel of an organic light emitting display according to an embodiment of the present invention,
FIG. 2 is a cross-sectional view of a part of an organic light emitting display according to an embodiment of the present invention shown in FIG. 1;
3 is a cross-sectional view showing more specifically the connection relationship between the thin film transistor layer and the first electrode layer shown in FIG. 2;

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numerals refer to like elements throughout the specification.

1 to 3, an OLED display according to an embodiment of the present invention will be described. FIG. 1 is a circuit diagram showing one pixel of an organic light emitting diode display according to an embodiment of the present invention. FIG. 2 is a view illustrating a part of a region of the organic light emitting display according to an embodiment of the present invention shown in FIG. And FIG. 3 is a cross-sectional view showing more specifically the connection relationship between the thin film transistor layer and the first electrode layer shown in FIG.

1, one pixel of an OLED display according to an exemplary embodiment of the present invention includes a cell driver DU connected to a gate line GL, a data line DL, and a power source line PL, And a white organic light emitting element WOLED connected between the ground terminal DU and the ground GND.

The cell drive unit DU includes a switch thin film transistor T1 connected to the gate line GL and the data line DL and a switch thin film transistor T1 connected to the switch thin film transistor T1 and the power supply line PL and the white organic light emitting element WOLED A driving thin film transistor T2 connected to one electrode and a storage capacitor C connected between the power supply line PL and the drain electrode of the switch thin film transistor T1.

The gate electrode of the switch thin film transistor T1 is connected to the gate line GL, the source electrode thereof is connected to the data line DL and the drain electrode thereof is connected to the gate electrode of the driving TFT T2 and the storage capacitor C . The source electrode of the driving thin film transistor T2 is connected to the power supply line PL and the drain electrode thereof is connected to the first electrode of the white organic light emitting diode WOLED. The storage capacitor C is connected between the power supply line PL and the gate electrode of the driving thin film transistor T2.

The switch thin film transistor T1 is turned on when a scan pulse is supplied to the gate line GL to supply the data signal supplied to the data line DL to the gate electrode of the storage capacitor C and the drive thin film transistor T2 do. The driving thin film transistor T2 controls the current I supplied from the power supply line PL to the white organic light emitting element WOLED in response to the data signal supplied to the gate electrode to reduce the amount of light emitted from the white organic light emitting element WOLED . Even if the switch thin film transistor T1 is turned off, the driving thin film transistor T2 supplies a constant current I until the data signal of the next frame is supplied by the voltage charged in the storage capacitor C, Thereby maintaining the light emission of the organic light emitting device WOLED.

2 and 3, the OLED display according to the embodiment of the present invention includes a thin film transistor substrate TFT_S, a color filter substrate CF_S attached to a thin film transistor TFT_S by an adhesive layer 300, .

The thin film transistor array substrate TFT_S includes a first substrate 100 made of an insulating material, a gate electrode G formed on the first substrate 100 and extending from the gate line, a gate electrode G covering the gate electrode G, A semiconductor active layer A formed on a region corresponding to the gate electrode G on the gate insulating film GI and a part of the semiconductor active layer A are exposed and separated from each other on the gate insulating film GI And a source electrode (S) and a drain electrode (D) formed.

Although the thin film transistor T2 has been described with respect to the thin film transistor of the gate bottom structure in which the gate electrode G is formed under the source electrode S and the drain electrode D The present invention is not limited thereto and it should be understood that the gate electrode includes a gate top structure of a thin film transistor formed on the source / drain region. Since the thin film transistor of the gate top structure is a well-known structure, a detailed description thereof will be omitted.

The thin film transistor array substrate TFT_S also includes a first protective film PAS1 made of an inorganic material so as to cover the source electrode S and the drain electrode D and a second protective film PAS2 covering the entire surface of the driving thin film transistor T2, (PAS2) made of an organic material.

Here, the semiconductor active layer (A) is an example in which the semiconductor active layer (A) is also formed as a silicon semiconductor active layer. However, the semiconductor active layer (A) may be formed of an oxide semiconductor. In this case, an etch stopper is formed on the semiconductor active layer A so that the semiconductor active layer is not exposed. The oxide semiconductor is formed of, for example, an oxide containing at least one metal selected from Zn, Cd, Ga, In, Sn, Hf and Zr. A thin film transistor including such an oxide semiconductor has advantages of a higher charge mobility and a lower leakage current characteristic than a thin film transistor including a silicon semiconductor active layer. Further, a thin film transistor including an oxide semiconductor can be subjected to a low temperature process, and advantageously has a large area.

The thin film transistor array substrate TFT_S also includes a reflective film 120 formed on the front surface of the second protective film PAS2. A contact hole CH is formed in the first protective film PAS1, the second protective film PAS2 and the reflective film 120 so that the drain electrode D of the thin film transistor T2 is exposed.

The thin film transistor array substrate TFT_S further includes a plurality of first electrodes 130R, 130G, and 130B formed on the reflective film 120 and separated by the banks 140, and a plurality of first electrodes 130R, A white organic light emitting device 150 covering the first electrodes 130R, 130G and 130B and a second electrode 160 formed on the white organic light emitting device 150. [ The plurality of first electrodes 130R, 130G, and 130B may be formed to have different thicknesses. A third protective layer 170 may be formed on the second electrode 160 to protect the second electrode 160.

The color filter substrate CF_S includes a second substrate 200 having concave portions 200a formed corresponding to the first electrodes 130R, 130G, and 130B of the thin film transistor array substrate TFT_S, And a color filter layer 220R, 220G, and 220B formed on the high-viscosity planarization layer 210. The color filter layers 220R, 220G, and 220B are formed on the first substrate 200 and the second substrate 200, respectively.

The high viscosity flattening film 210 may be selected from materials having a refractive index in the range of 1.2 to 1.4. An example of the high viscosity flattening film 210 is poly [4,5-difluoro-2,2-bis (trifluoromethyl) -1,3-dioxol-cetetrafluoroethylene] represented by Chemical Formula 1 (2, 2, 3, 3, 4, 4, 4- < RTI ID = 0.0 > Heptafluorobutyl acrylate), poly (2,2,3,4,4,4-hexafluorobutyl acrylate) represented by the formula (3), poly (2,2,2-trifl o Poly (2,2,2-trifluoromethyl acrylate) represented by the formula (5), poly (1,1,1,3,3,3-hexafluoro Butyl acrylate), and the like.

The color filter layers 220R, 220G and 220B include a red color filter layer 200R, a green color filter layer 220G and a blue color filter layer 220B and are bounded by black matrices 230. [ The color filter layers 220R, 220G and 220B are formed corresponding to the concave portions 200a of the second substrate 200 and the first electrodes 130R, 130G and 130B of the TFT array substrate TFT_S, The matrices 140 are formed corresponding to the banks 140 of the thin film transistor array substrate TFT_S.

According to the organic light emitting display according to the embodiment of the present invention described above, the concave portion 200a formed at the position of the second substrate 200 corresponding to the color filter layers 220R, 200G, the green color filter layer 200G and the blue color filter layer 200B are formed in accordance with the refractive index difference between the air gap air layer and the high viscosity material layer since the high viscosity planarization layer 210 is formed on the upper surface of the red color filter layer 200R, The light efficiency is changed.

Next, referring to Table 1, the optical efficiency of the OLED display according to the exemplary embodiment of the present invention will be described in detail. Table 1 is data showing the luminance of light emitted through the red, green, and blue color filters of the OLED display device according to the comparative example and the OLED display device according to the first to fourth embodiments of the present invention. The comparative examples in Table 1 are organic light emitting display devices in which concave portions of the high viscosity flattening film and the second substrate are not formed. Examples 1 to 4 are organic light emitting display devices having concave portions of the high viscosity flattening film and the second substrate, 1 is the refractive index of the high viscosity flattening film of 1.2, Example 2 is the refractive index of the high viscosity flattening film is 1.3, Example 3 is the refractive index of the high viscosity flattening film is 1.3 and Example 4 is the luminance of the high viscosity flattening film is 1.4 Respectively.

Comparative Example
(cd / m ² ) Example 1
(Refractive index 1.2)
(cd / m ² ) Example 2
(Refractive index 1.3)
(cd / m ² ) Example 3
(Refractive index 1.4)
(cd / m ² ) Red color filter 25.3 25.8 27.3 27.7 Green filter filter 39.2 41.0 40.4 38.8 Blue filter filter 2.1 202 2.2 2.2

As can be seen from the above experimental results, in comparison between Example 1 and Comparative Example, the light transmitted through the red color filter was improved by 2% in the first embodiment compared to the comparative example, and the light transmitted through the green color filter The first embodiment is improved by 4.6% as compared with the comparative example, and the light transmitted through the blue color filter is improved by 4.8% as compared with the comparative example of the first embodiment. In comparison between Example 2 and Comparative Example, the light transmitted through the red color filter was improved by 7.9% in the second embodiment compared to the comparative example, and the light transmitted through the green color filter was 3.1 %, And the light transmitted through the blue color filter is improved by 4.8% as compared with the comparative example. In comparison between Example 3 and Comparative Example, the light transmitted through the red color filter is improved by 9.5% in the third embodiment compared to the comparative example, and the light transmitted through the green color filter is light- 1.0%, and that of the light transmitted through the blue color filter is 4.8% higher than that of the comparative example.

From Table 1 above, it can be seen that the overall light efficiency of the organic light emitting display according to the embodiments of the present invention is improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. For example, in the description of the embodiments of the present invention, the first protective film for protecting the thin film transistor and the second protective film for planarization are separately formed, but only one of the first protective film and the second protective film may be formed. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the invention but should be defined by the claims.

100: first substrate 110: TFT forming layer
120: reflection plates 130R, 130G, 130B:
140: Bank 150: White OLED
160: second electrode 170: protective film
200: second substrate 200a: concave portion
210: high viscosity flattening film 220: color filter layer
220R: Red color filter 220G: Green color filter
220B: blue color filter 230: black matrix
300: adhesive layer

Claims (7)

A thin film transistor substrate in which a white organic light emitting device is formed between a plurality of first electrodes and second electrodes respectively connected to a plurality of thin film transistors formed on a first substrate; And
And a color filter substrate disposed opposite to the thin film transistor substrate,
Wherein the color filter substrate includes a second substrate having a plurality of concave portions formed at positions corresponding to the first electrodes, a high viscosity planarization film formed on the second substrate, and a plurality of And color filter layers.
The method according to claim 1,
Wherein the high viscosity flattening film has a refractive index in the range of 1.2 to 1.4.
The method according to claim 1,
Wherein the high viscosity planarizing film comprises at least one of poly [4,5-difluoro-2,2-bis (trifluoromethyl) -1,3-dioxol-cetetrafluoroethylene] 2-bis (trifluoromethyl) -1,3-dioxole-co-tetrafluoroethylene]), poly (2,2,3,3,4,4,4-heptafluorobutyl acrylate) , 4,4,4-hexafluorobutyl acrylate), poly (2,2,2-trifluoromethylmethacrylate), poly (2,2,2-trifluoromethyl acrylate), poly Hexafluorobutyl acrylate, 1,1,1,3,3,3-hexafluorobutyl acrylate, and the like.
4. The method according to any one of claims 1 to 3,
Wherein the plurality of color filter layers are formed corresponding to the concave portions of the second substrate.
5. The method of claim 4,
And a reflective layer formed between the thin film transistor layer and the first electrodes.
6. The method of claim 5,
Wherein the plurality of first electrodes are connected to the thin film transistors through contact holes formed in the reflective film.
The method according to claim 1,
Wherein neighboring first electrodes among the plurality of first electrodes are separated by a bank.

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