KR102126538B1 - Color filter and organic light emmiting diode including the same - Google Patents

Abstract

The present invention discloses an organic light emitting device. More specifically, the present invention relates to an organic light emitting device including a color filter that satisfies the color gamut of ITU-R BT.709 while maintaining a thin film structure.
According to an embodiment of the present invention, by optimizing the content ratio of violet in the colorant of the blue color filter of the organic light emitting device and shifting Bx, it is possible to improve the transmittance while satisfying the color gamut of ITU-R BT.709. It has an effect.

Description

Color filter and organic light emitting device including the same {COLOR FILTER AND ORGANIC LIGHT EMMITING DIODE INCLUDING THE SAME}

The present invention relates to an organic light emitting device, and particularly to an organic light emitting device including a color filter that satisfies the color gamut of ITU-R BT.709 while maintaining a thin film structure.

As a flat panel display device proposed to replace the existing cathode ray tube display device, a liquid crystal display, a field emission display, and a plasma display panel (Plasma Display Panel) and organic light-emitting devices (Organic Light-Emitting Diode Display, OLED Display).

Among them, the organic light emitting device has a high luminance and a low operating voltage characteristic of the organic light emitting diode provided on the display panel, and is a self-emission type that emits light by itself, thus having a large contrast ratio and realizing an ultra-thin display. This has the advantage of being possible. In addition, the response time is easy to implement a moving image to a few microseconds (㎲), there is no limitation in viewing angle and it has stable characteristics even at low temperatures.

1 is a view schematically showing a structure of one pixel of a conventional organic light emitting diode.

Referring to FIG. 1, a conventional organic light emitting diode is sequentially formed on a substrate 10, and a TFT array layer 20 that controls signals applied to each pixel and three primary colors of R, G, and B are implemented. It consists of a color filter 30 for, an OLED layer 40 that emits light according to the formed electric field, and an encapsulation layer 50 that protects a lower configuration.

In the organic light emitting device having such a structure, the color filter 30 is provided to display R, G, and B primary colors, and color matching of a light source and a color filter is required to realize an accurate color sense. In the case of other types of flat panel display devices, for example, liquid crystal display devices, the luminance and color reproducibility of the light source change according to the type of phosphor for each LED that is a light source, and the combination with a resist that forms a color filter accordingly To adjust the color gamut and color coordinates.

In general, a light source of a liquid crystal display device combines phosphors such as yellow, green, and red on a blue chip to realize white, and the spectrum is For reference, blue has a sharp emission peak, and yellow, yellow and red, or green and red are implemented to have a slow emission peak. Accordingly, in the case of blue when designing a color filter in the liquid crystal display, it is possible to design a blue color filter of a relatively light color due to the rapid emission peak characteristics of blue.

In addition, in the case of an organic light emitting display device using a white organic light emitting diode (W-OLED), as shown in FIG. 2, the white organic light emitting diode (W-OLED) is a white LED (W-LED) when viewed as a whole light source ), but there is a difference between the blue peak position and the bandwidth, and the blue peak has a gentle characteristic, so it is necessary to set the blue color filter relatively dark. In the conventional organic light emitting display device, the luminescence peak was adjusted by adjusting the color concentration of the colorant or the film thickness of the brook color filter.

Particularly, in a video display system such as a TV using an existing organic light emitting device, when setting the characteristics of the blue color filter with the existing blue coordinates, the color coverage becomes insufficient compared to ITU-R BT.709, and this is improved. In order to increase the thickness of the color filter, a problem that transmittance decreases occurs.

3 is a view showing the characteristics of an organic light emitting diode (OLED) according to ITU-R BT.709 and a blue color filter in a CIE color coordinate.

Referring to FIG. 3 and Table 1 below, a typical color filter (M1) of a blue organic light emitting diode (B-OLED) has a CIE x,y of 0.142 and 0.060, respectively, significantly out of ITU-R BT.709, and brightness (Y) also has a low characteristic of 2.04. Accordingly, if the content ratio of the colorant is adjusted to satisfy the color gamut of ITU-R BT.709, M2 is an example of adjusting the colorant content ratio of a general color filter, CIE x,y to 0.141 and 0.055, respectively. When adjusted, it is possible to satisfy ITU-R BT.709, and the brightness (Y) at this time is 5.8%, which can be improved compared to the prior art.

x y Y Gamut
(NTSC, CIE1931) Coverage
(BT.709, CIE1976 Gamut
(BT.709, CIE1976) M1 0.142 0.060 2.07 86.6% 99.0% 113.9% M2 0.141 0.055 2.19
(5.8% increase) 87.2% 100.0% 116.4%

However, it is difficult to expect the above-mentioned effect as a method of adjusting the content ratio of the colorant according to the prior art, and in particular, when adjusting the film thickness of the color filter, there is a limitation that a problem of a decrease in transmittance occurs.

The present invention has been devised to solve the above-mentioned problems, and the present invention provides an increase in film thickness and a decrease in transmittance while satisfying the color gamut of ITU-R BT.709 in an organic light emitting device using a color filter. An object of the present invention is to provide an improved color filter and an organic light emitting device including the same.

To achieve the above object, a color filter according to a preferred embodiment of the present invention, Methylmethacrylate-Butadiene-Styrene (MBS); Blue pigment added to the MBS; And a violet die added to the MBS, and the content ratio of the violet die is 10 mass% to 30 mass%.

In addition, in order to achieve the above object, an organic electroluminescent device according to a preferred embodiment of the present invention, the substrate; A TFT array layer in which a plurality of pixels are defined on a substrate and controlling signals applied to each pixel; A color filter layer formed from the top of the TFT array layer and including red, green, blue and white color filters; An anode layer formed over the color filter; An organic emission layer formed on the anode layer to emit light; A cathode layer formed to face the anode layer; And an insulation layer covering an upper portion of the cathode layer, wherein the blue color filter comprises: Methylmethacrylate-Butadiene-Styrene (MBS); Blue pigment added to the MBS; And a violet die added to the MBS, and the content ratio of the violet die is 10 mass% to 30 mass%.

The color filter according to the embodiment of the present invention and the organic light emitting device including the same satisfy the color gamut of ITU-R BT.709 by shifting Bx by optimizing the content ratio of violet in the colorant of the blue color filter While there is an effect that can improve the transmittance.

1 is a view schematically showing a structure of one pixel of a conventional organic light emitting diode.
2 is a view showing the light spectrum of a white organic light emitting diode (W-OLED) and a white LED (W-LED).
3 is a view showing the characteristics of an organic light emitting diode (OLED) according to ITU-R BT.709 and a blue color filter in a CIE color coordinate.
4 is a view schematically showing the structure of an organic light emitting device according to an embodiment of the present invention.
5 is a view showing the change in Bx and BY according to the content ratio of the blue and violet colorant in the design of the blue color filter.
6 is a view showing the characteristics of an organic light emitting diode (OLED) to which ITU-R BT.709, a conventional blue color filter, and a Bx shifted blue color filter are applied in CIE color coordinates.
7 is a cross-sectional view of one pixel of an organic light emitting device including a color filter according to an embodiment of the present invention.

Hereinafter, a color filter and an organic light emitting device including the same according to a preferred embodiment of the present invention will be described with reference to the drawings.

4 is a view schematically showing the structure of an organic light emitting device according to an embodiment of the present invention.

Referring to FIG. 4, in the organic light emitting device of the present invention, a plurality of pixels are defined on the substrate 100, and a TFT array layer 200 that controls signals applied to each pixel and incident from the top A color filter layer 300 for realizing red, green, and blue, an overcoat layer 400 for planarizing the upper layer of the color filter layer 300, and an anode layer serving as a pixel electrode on top of the overcoat layer 400 ( 500), an organic light emitting layer 600 formed on the anode layer 400 to emit light, a cathode layer 700 serving as a common electrode facing the anode layer 400, and a cathode layer 700 ), covering the upper portion of the insulating layer 800 to protect the lower component and prevent moisture permeation.

The organic light emitting device having such a structure is a structure in which light is emitted in a downward direction based on the organic light emitting layer 600, and the anode layer 500 may be made of a transparent metal.

In the organic light emitting device, one pixel is divided into four sub-pixels, that is, a red (R) pixel, a green (G) pixel, and a blue (B) pixel and a white (W) pixel, and correspond to each pixel. Color filters of different colors are supported. In particular, the illustrated structure relates to an organic light emitting device having a separate sub-pixel for white (W), in which case each of the sub-pixels R, G, B, and W may be formed in a quad (quad) type. Can. Here, the white (W) pixel may be formed without a separate color resist, or may be formed of a transparent resist or an organic film that replaces it to match the height with other color resists. Here, the overcoat layer 400 covering the color filter layer 300 may be omitted according to a designer's intention.

In particular, the organic electroluminescent device should be designed with a relatively dark blue color filter compared to the white LED, and thus the change in the Bx and BY of the CIE color coordinates was tested by adjusting the content ratio of the blue and violet colorants added to the blue color filter.

5 is a view showing the change in Bx and BY according to the content ratio of the blue and violet colorant in the design of the blue color filter.

Referring to FIG. 5, when the ratio of the violet colorant is adjusted during design in the blue color filter, it can be seen that BY gradually increases from 20% to 30% by mass, and then gradually falls from 30% by mass. In addition, Bx continues to increase from 20 mass% to 50 mass%.

Therefore, in designing a blue color filler, if the ratio of the violet colorant is determined between 20% and 30% by mass, the brightness (BY) can be increased.

In addition, the organic electroluminescent device according to an embodiment of the present invention is characterized in that, among the color resists constituting the color filter 300, Xanthene-based violet dye is used as a colorant for a color pigment for blue. .

The conventional blue color filter (M1) was prepared by mixing Methylmethacrylate-Butadiene-Styrene (MBS) with blue pigment B15:6 and Dipyrrolmethane-based violet dye at a content ratio of 5:5. , In the comparative example of the present invention, as shown in Table 2, the blue pigment (blue pigment) B15:6 and Dipyrrolmethane series to satisfy the ITU-R BT.709 color gamut by shifting Bx in the CIE color coordinates The violet dye was mixed at a ratio of 6:4 (bx shift1), and the B15:6 and Xantene-based violet dye were mixed at a ratio of 8:2 (bx shift2) to experiment.

M1 Bx shift 1 Bx shift 2 coloring agent B15:6 / Violet Dye B15:6 / Violet Dye B15:6 / Violet Dye MBS B:V = 5:5 MBS B:V = 6:5 MBS B:V = 8:2 MBS Dye type Dipyrrolmethane series Xanthene series

In Table 2, Bx shift 1 compared to the conventional (M1) has a disadvantage in that the patterning characteristics of the color filter are not good, and characteristics such as light resistance and heat resistance are deteriorated as the content of the violet die increases. On the other hand, Bx shift 2 has better coloring ability than the dipyrrolmethane-based violet die by using Xanthene-based violet die, and the same color characteristics can be obtained even with a smaller amount.

Accordingly, the color filter of the present invention is produced by mixing the blue pigment B15:6 and the Xantene-based violet dye at a ratio of 8:2, and accordingly, the ratio of the violet dye Silver is 10% by mass to 30% by mass, and is characterized by being manufactured by mixing one Xantene-based material or two or more Xantene-based materials.

On the other hand, Figure 6 is a diagram showing the characteristics of an organic light emitting diode (OLED) to which ITU-R BT.709, a conventional blue color filter, and a Bx shifted blue color filter are applied in CIE color coordinates. Referring to the above, the general color filter M1 of the blue organic light emitting diode (B-OLED) has a CIE x,y of 0.142 and 0.060, respectively, and accordingly, the color gamut and overlap ratio of ITU-R BT.709 are 100% according to the prior art. The color filter (M2) having a colorant adjusted so as to be satisfactory has a brightness (Y) of 5.8% when CIE x and y are 0.141 and 0.055, respectively. In contrast, it can be seen that the bx shifted blue color filter M3 according to an embodiment of the present invention has a CIE x,y of 0.148 and 0.058, respectively, and the brightness (Y) of 2.36 is increased by 14.0%.

X y Y Gamut
(NTSC, CIE1931) Coverage
(BT.709, CIE1976) Gamut
(BT.709, CIE1976) M1 0.142 0.060 2.07 86.6% 99.0% 113.9% M2 0.141 0.055 2.19
(5.8% increase) 78.7% 100.0% 108.3% M3 0.148 0.058 2.36
(14.0% increase) 77.8% 100.0% 105.9%

Hereinafter, a structure of a blue pixel of an organic light emitting device including a color filter to which a content ratio according to an embodiment of the present invention is applied will be described with reference to the drawings.

7 is a cross-sectional view of one pixel of an organic light emitting device including a color filter according to an embodiment of the present invention.

Referring to FIG. 7, in one pixel of the organic light emitting device of the present invention, at least one thin film transistor TR for controlling an organic diode is formed on one pixel PX on the transparent substrate 100. The location corresponding to the thin film transistor TR is made of pure polysilicon, the central portion of which is a first region 203a constituting a channel, and a second region doped with a high concentration of impurities on both sides of the first region 203a ( A semiconductor layer 203 composed of 203b and 203c is formed.

Here, although not shown, a buffer layer (not shown) may be formed of an insulating material, particularly an inorganic insulating material, silicon oxide (SiO ₂ ) or silicon nitride (SiNx). Such a buffer layer (not shown) is omitted as being formed to minimize the problem of deterioration of the properties of the semiconductor layer 203 due to the release of alkali ions from the inside of the substrate 100 in the crystallization process of the semiconductor layer 203, which is a subsequent process. It is possible.

Further, a gate insulating layer 205 is formed on the buffer layer including the semiconductor layer 203.

Further, a gate electrode 207 is formed above the gate insulating layer 205 corresponding to the first region 203a of the semiconductor layer 203 in the thin film transistor TR.

Here, the gate electrode 207 is a first metal material having low resistance properties, for example, aluminum (Al), aluminum alloy (AlNd), copper (Cu), copper alloy, molybdenum (Mo), and molybdenum titanium (MoTi) It may be formed of a single-layer structure made of any one or a double-layer or triple-layer structure made of two or more first metal materials. The drawing shows an example in which the gate electrode 207 has a single layer structure.

In addition, an interlayer insulating film 209 made of an insulating material, for example, an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiNx), is formed on the entire display area of the substrate including the gate electrode 207. Here, the interlayer insulating layer 209 and the lower gate insulating layer 205 have semiconductor layer contact holes exposing each of the second regions 203b and 203c located on both sides of the first region 203a of each semiconductor layer 203. Is formed.

On the interlayer insulating layer 209 including the semiconductor layer contact hole, the second regions 203b and 203c exposed through the semiconductor layer contact hole (not shown) of the thin film transistor T are respectively made of a second metal material. The source electrode 213a and the drain electrode 213b are formed. Accordingly, the source electrode 213a and the drain electrode 213b that are formed to be separated from the semiconductor layer 203, the gate insulating layer 205, the gate electrode 207, and the interlayer insulating layer 209 sequentially stacked are thin film transistors. (TR).

The second metal material is, for example, aluminum (Al), aluminum alloy (AlNd), copper (Cu), copper alloy, molybdenum (Mo), molybdenum titanium (MoTi), chromium (Cr) and titanium (Ti) It can be made of any one or more material combinations.

In addition, although both the source electrode 213a and the drain electrode 213b of the thin film transistor TR are shown to have a single layer structure, this may achieve a double layer or triple layer structure by a combination of two metal materials.

In this case, although not illustrated in the drawing, one pixel PX may further include at least one other thin film transistor (not shown) having the same stacked structure in addition to the thin film transistor TR.

On the other hand, although the drawing shows an example in which the thin film transistor TR is a top gate type, it is applicable by replacing it with a bottom gate type having an amorphous silicon semiconductor layer.

When the thin film transistor TR is composed of a bottom gate type, the stacked structure includes a gate electrode, a gate insulating film, an active layer of pure amorphous silicon, and a semiconductor layer made of an ohmic contact layer of impurity amorphous silicon spaced apart from each other, It may be formed of a source electrode and a drain electrode spaced apart.

In addition, a color filter layer 300 made of a color filter including blue in which a content ratio of a violet colorant is adjusted is formed on the same layer as the source electrode and the drain electrode. The color filter constituting the color filter layer 300 is added with a violet colorant in which one substance of Xanthene series or two or more substances of Xanthene series is combined, and the content of violet colorant compared to blue is 10 mass% to 30 mass% Is done. In the drawing, a structure in which the color filter layer 300 is provided below the organic light emitting layer 525 as a back light emitting method in which light is emitted in the direction of the substrate 100 is shown, but the color filter layer 300 shows the structure of the organic light emitting layer 525. It is formed on the upper layer, the cathode layer 527 is made of a transparent metal, the front light emission method in which light is emitted in the upper direction is also applicable.

In addition, an overcoat layer 400 having a drain contact hole exposing the drain electrode 213b is stacked on the top of the thin film transistor TR. As the overcoat layer 400, an insulating material, for example, an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiNx) is used, or any of organic insulating materials including photo-acyl. One can be used.

In addition, the first electrode having a shape separated by each pixel PX is contacted through the drain electrode 213c and the drain contact hole (not shown) of the thin film transistor TR to the upper portion of the overcoat layer 400 ( 521) is formed.

In addition, an upper portion of the first electrode 521 serves to divide the boundary of each pixel PX, and an insulating material, in particular, benzocyclobutene (BCB), polyimide, or photoacrylic (photo) a bank 523 made of acryl) is formed. The bank 523 is formed to surround each pixel PX so as to overlap the edge of the first electrode 521, and when viewed as a whole of the organic EL device, has a lattice shape having a plurality of openings.

An organic emission layer 525 composed of an organic emission pattern (not shown) emitting red, green, and blue light is formed on an upper portion of the first electrode 521 in the pixel PX surrounded by the bank 523. The organic light emitting layer 525 may be composed of a single layer made of an organic light emitting material, or a hole injection layer, a hole transporting layer, and a light emitting material layer (not shown in the drawing) to increase light emission efficiency It may be composed of multiple layers of an emitting material layer, an electron transporting layer, and an electron injection layer.

In addition, a second electrode 527 is formed on the organic emission layer 525 and the bank 523. At this time, the first electrode 521 and the second electrode 527 and the organic light emitting layer 525 interposed between the two electrodes 521 and 527 form one organic light emitting diode.

Therefore, the organic light emitting diode is provided from the holes injected from the first electrode 521 and the second electrode 527 when a voltage reflecting a predetermined gradation value is applied to the first electrode 521 and the second electrode 527. The electrons are transported to the organic light emitting layer 525 to form excitons. These excitons emit light when they transition from the excited state to the ground state and emit in the form of visible light. At this time, since the emitted light passes through the transparent first electrode 521 and goes outward, the organic light emitting device implements an arbitrary image.

Meanwhile, an encapsulation layer is formed on the substrate 100 including the second electrode 527 to protect the lower pattern and prevent moisture permeation. The encapsulation layer includes a first passivation film 629, an organic film 631, a second passivation film 633, an adhesive 635, and a protective layer 637.

First, the first passivation film 629 is formed of an insulating material, particularly a first passivation film 629 made of silicon oxide (SiO ₂ ) or silicon nitride (SiNx), which is an inorganic insulating material. The first passivation film 629 cannot prevent the penetration of moisture into the organic light emitting layer 625 only with the second electrode 627, and thus the first passivation functioning as a protective layer on the second electrode 627 By forming the film 629, moisture penetration into the organic light emitting layer 625 is minimized. In addition, an organic film 631 made of a polymer organic material such as a polymer is formed on the first passivation film 629. At this time, as the polymer thin film constituting the organic film 631, olefin-based polymers (polyethylene, polypropylene), polyethylene terephthalate (PET), epoxy resin (epoxy resin), fluoro resin (fluoro resin), polysiloxane (polysiloxane), etc. Can be used.

In addition, an insulating material, for example, an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiNx), is used to prevent moisture from penetrating through the organic film 631 on the front surface of the substrate including the organic film 631. A second passivation film 633 is formed, and the second passivation film 633 is not only the end of the organic film 631, but also the first passivation film 629 below it and the outer bank 623. It is configured to cover the part efficiently to block moisture penetration.

In addition, a protective film 637 is positioned opposite to the encapsulation of the organic light emitting diode on the front surface of the substrate including the second passivation film 633, and is transparent between the substrate 100 and the protective film 637. An adhesive 635 made of any one of a frit, an organic insulating material, and a polymer material having adhesive properties is completely interposed between the substrate 601 and the barrier film 637 without an air layer. The present invention uses PSA (Press Sensitive Adhesive) as an example of the adhesive 635.

According to this structure, the organic electroluminescent device including the color filter of the present invention is a Xantene-based violet colorant used in a blue color register forming a B color filter among R, G, B, and W color filters, By setting the content ratio with the blue colorant to about 7:3, the brightness of the color filter can be improved without increasing the thickness.

Although many matters are specifically described in the above description, it should be interpreted as an example of a preferred embodiment rather than limiting the scope of the invention. Therefore, the invention should not be determined by the described embodiments, but should be determined by equivalents to the claims and claims.

100: substrate 200: TFT array layer
300: color filter layer 400: overcoat layer
500: anode layer 600: organic light emitting layer
700: cathode layer 800: insulation layer

Claims (8)

Methylmethacrylate-Butadiene-Styrene (MBS);
Blue pigment added to the MBS; And
It is made of a violet die added to the MBS,
A color filter comprising a blue color filter formed by setting the content ratio of the blue pigment and the violet die of the Xantene series to 7:3. delete Board;
A TFT array layer in which a plurality of pixels are defined on a substrate and controlling signals applied to each pixel;
A color filter layer formed from the top of the TFT array layer and including red, green, blue and white color filters;
An anode layer formed over the color filter layer;
An organic emission layer formed on the anode layer to emit light;
A cathode layer formed to face the anode layer; And
And an insulating layer covering an upper portion of the cathode layer,
The blue color filter,
Methylmethacrylate-Butadiene-Styrene (MBS);
Blue pigment added to the MBS; And
It is made of a violet die added to the MBS,
The organic electroluminescent device, characterized in that formed by setting the content ratio of the blue pigment and the violet die of the Xantene series to 7:3. delete The method of claim 3,
Between the color filter layer and the anode layer,
An organic electroluminescent device characterized in that the overcoat layer covering the color filter is further formed. The method of claim 3,
The TFT array layer,
A semiconductor layer formed on the substrate;
A gate electrode formed on the semiconductor layer;
An interlayer insulating film formed over the entire display area of the substrate including the gate electrode; And
Source and drain electrodes formed in contact with regions of the exposed semiconductor layer, including semiconductor layer contact holes formed on the interlayer insulating film
Organic electroluminescent device comprising a. The method of claim 3,
The cathode layer,
An organic electroluminescent device characterized in that it is a back light emission method made of a transparent metal. The method of claim 3,
Light that passes through the color filter layer and is emitted,
Organic electroluminescent device characterized in that it has a characteristic included in the ITU-R BT.709 area.

Images