Color filter array and organic light-emitting display device using the same

A color filter array is provided that is capable of implementing full color with improved light-emitting efficiency and color coordinate values from a mixed light of blue and red, and an organic light-emitting display device using the same. A color filter array receiving a mixed light of blue wavelength light and red wavelength light to implement full color according to an embodiment of the invention comprises a red filter, a green filter, and a blue filter. The red filter includes a first color conversion material for converting the blue wavelength light into green light and red light and a green blocking material for blocking the green light. The green filter includes a second color conversion material for converting the blue wavelength light into green light and red light and a red blocking material for blocking the red light. The blue filter includes a red blocking material for blocking the red wavelength light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean Patent Application Nos. 2005-131548, 2005-131549 and 2005-131550, all filed on Dec. 28, 2005 in the Korean Intellectual Property Office, the entire disclosures of which are incorporated herein by reference.

BACKGROUND

The invention relates to a color filter array and a flat display device using the same, and more particularly, to a color filter array capable of implementing full color with improved light-emitting efficiency and color coordinate values from a mixed light of blue and red, and an organic light-emitting display device.

Further, the invention relates to an organic light-emitting display device in which a light-emitting layer can be easily formed, and the color coordinate values of the light-emitting layer do not vary severely according to the driving voltage and current density.

As a method of implementing full color in a flat display device, particularly, an organic light-emitting element, generally, a 3-color light-emitting method, a color filter method, and a color conversion method are well known. The 3-color light-emitting method uses the respective Red (R), Green (G), Blue (B) light sources to emit red light, green light, and blue light, the color filter method splits light primarily from a white colored light-emitting source through a color filter into red light, green light, and blue light, and the color conversion method splits light from a blue light-emitting source into red light, green light, and blue light using a color conversion material (phosphor) instead of a color filter.

The 3 color light-emitting method has a problem in that the lifespan of any one color determines the lifespan of the entire system, the color filter method has a problem in that the amount of light is decreased since white color is absorbed into a color filter, and the color conversion method has a problem in that a color conversion material is excited by blue light, thereby reducing contrast.

A color light-emitting device is disclosed inFIG. 1, which is a schematic diagram of a conventional color light-emitting device. The device includes a red filter for converting blue light and green light from white light to red light and transmitting only red light, and a green filter for converting blue light from white light to green light and transmitting only green light. However, the color light-emitting device has problems in using three wavelengths in which the light-emitting efficiency and color purity of red light is not good, the variation of color coordinate values of the 3 color light-emitting sources is severe, and its manufacturing process is complex.

SUMMARY OF THE INVENTION

The invention is designed to solve the above problems, and provides a color filter array in which a mixed light of blue light and red light emits from a light-emitting source and a color filter is formed including a color conversion material and a light blocking material, and an organic light-emitting display device using the source and filter.

A color filter array receiving a mixed light of blue wavelength and red wavelength lights to implement full color according to an embodiment of the invention comprises a red filter, a green filter, and a blue filter. The red filter comprises a first color conversion material for converting the blue light to green light and red light, and a green blocking material for blocking the green light. The green filter comprises a second color conversion material for converting the blue light to green light and red light, and a red blocking material for blocking the red light. The blue filter comprisies a red blocking material for blocking the red light.

In addition, an organic light-emitting display device according to another embodiment of the invention comprises a substrate, a first electrode formed on one surface of the substrate, an organic light-emitting layer formed on the first electrode that emits a mixed light of blue light and red light, a second electrode formed on the organic light-emitting layer, and a red filter, a green filter, and a blue filter formed on the other surface of the substrate. The red filter comprises a first color conversion material for converting blue light from the organic light-emitting layer to green light and red light, and a green blocking material for blocking the green light. The green filter comprises a second color conversion material for converting blue light from the organic light-emitting layer to green light and red light, and a red blocking material for blocking the red light. The blue filter comprises a red blocking material for blocking the red light from the organic light-emitting layer.

In addition, an organic light-emitting display device according to still another embodiment of the invention comprises a substrate, a first electrode formed on one surface of the substrate, an organic light-emitting layer formed on the first electrode for emitting a mixed light of blue light and red light, a second electrode formed on the organic light-emitting layer, and a red filter, a green filter, and a blue filter formed on the outside of the second electrode. The red filter comprises a first color conversion material for converting blue light from the organic light-emitting layer to green light and red light, and a green blocking material for blocking the green light. The green filter comprises a second color conversion material for converting blue light from the organic light-emitting layer to green light and red light, and a red blocking material for blocking the red light. The blue filter comprises a red blocking material for blocking the red light from the organic light-emitting layer.

In addition, a red filter according to another embodiment of the invention comprises a color conversion material for converting blue light emitted from a light-emitting source radiating blue light and red light into green light and red light, and a green blocking material for blocking the green light.

In addition, an organic light-emitting display device according to another embodiment of the invention comprises a substrate, a first electrode formed on one surface of the substrate, an organic light-emitting layer formed on the first electrode for emitting a mixed light of blue light and red light, a second electrode formed on the organic light-emitting layer, and a red filter formed on the red pixel region of the other surface of the substrate, wherein the red filter comprises a color conversion material for converting the blue light emitted from the organic light-emitting layer into green light and red light, and a green blocking material for blocking the green light.

In addition, an organic light-emitting display device according to still another embodiment of the invention comprises a substrate, a first electrode formed on one surface of the substrate, an organic light-emitting layer formed on the first electrode for emitting a mixed light of blue light and red light, a second electrode formed on the organic light-emitting layer, and a red filter formed on a red pixel region of the outside of the second electrode, wherein the red filter comprises a color conversion material for converting the blue light emitted from the organic light-emitting layer into green light and red light, and a green blocking material for blocking the green light.

In addition, a green filter according to another embodiment of the invention comprises a color conversion material for converting blue light emitted from a light-emitting source radiating blue light and red light into green light and red light, and a red blocking material for blocking the red light.

In addition, an organic light-emitting display device according to still another embodiment of the invention comprises a substrate, a first electrode formed on one surface of the substrate, an organic light-emitting layer formed on the first electrode for emitting a mixed light of blue light and red light, a second electrode formed on the organic light-emitting layer, and a green filter formed on a green pixel region of the other surface of the substrate, wherein the green filter comprises a color conversion material for converting the blue light emitted from the organic light-emitting layer into green light and red light, and a red blocking material for blocking the green light.

In addition, an organic light-emitting display device according to still another embodiment of the invention comprises a substrate, a first electrode formed on one surface of the substrate, an organic light-emitting layer formed on the first electrode for emitting a mixed light of blue light and red light, a second electrode formed on the organic light-emitting layer, and a green filter formed on the outside of the second electrode, wherein the green filter comprises a color conversion material for converting the blue light emitted from the organic light-emitting layer into green light and red light, and a red blocking material for blocking the red light.

A color filter array according to the invention and an organic light-emitting display device employing such a color filter array improves the light-emitting efficiency and color coordinate values of red and green light for implementing full color from a mixed light of blue light and red light.

Further, the color filter array according to the invention improves manufacturing efficiency by providing the same color conversion materials to the red filter and green filter.

Still further, for the organic light-emitting display device according to the invention, the variation of color coordinate values according to the driving voltage and current density is not severe since its light-emitting layer is composed only of red and blue colors.

DETAILED DESCRIPTION

Hereinafter, embodiments of a color filter array according to the invention will be described in more detail with reference toFIG. 2.FIG. 2is a construction diagram of a color filter array according to an embodiment of the invention. According toFIG. 2, a color filter array comprises a transparent substrate, a red filter, a green filter, and a blue filter. In one embodiment, a light-emitting source used in the color filter is a light source in which blue and red lights are mixed. The light emitting source may be provided as a single layer or in multiple layers. The X coordinate is in the range of from 0.20 to 0.50, and the Y coordinate is in the range of from 0.20 to 0.43.

FIG. 3shows a light-emitting spectrum of a light source used in the color filter for an embodiment where a light-emitting source emits only blue light and red light, and for this embodiment, there are advantages in that the variation of color coordinate values of the light-emitting source is not severe according to driving voltage and current density, and the light-emitting source is easily manufactured.

In one embodiment, the transparent substrate on which color filters having the respective colors are formed, is made of a transparent material such as glass, transparent polymer, etc.

In one embodiment, the red filter comprises a first color conversion material and a green blocking material. The first color conversion material converts blue light from a light-emitting source to light with a green wavelength and a small amount of light with a red wavelength, and a graph illustrating a light-emitting spectrum of light penetrating the first color conversion material is shown inFIG. 4. In one embodiment, according toFIG. 4, the wavelength of light ranges from 450 nm to 630 nm and includes a green region ranging from 450 nm to 610 nm and a red region ranging from 610 nm to 630 nm.

In one embodiment, the first color conversion material may be made of a fluorescent pigment and a binder resin or only a fluorescent pigment. In an embodiment, a coumarin derivative such as 3-(2′-benzothiazolyl)-7-diethylaminocoumarin (hereinafter, referred to as coumarin 6), or 3-(2′-benzoimidazolyl)-7-N,N-diethylaminocoumarin (hereinafter, referred to as coumarin 7), Alq3, or inorganic pigments, or organic pigments with fluorescence may be used.

The green blocking material, which in one embodiment is formed abutting the first color conversion material, is composed of a pigment with transmittance over 50% in the wavelength ranging from 600 nm to 780 nm, or a material in which the pigment is dissolved or dispersed into a binder resin.FIG. 5is a graph illustrating a transmission spectrum of a green blocking material according to one embodiment.

In one embodiment the red filter is configured so that the color conversion material and green blocking material constitute two different layers. In another embodiment, the color filter may be configured with the color conversion material and green blocking material provided as a single mixed layer.

In an embodiment, blue light, which passes through the red filter, is converted to green and red light by the first color conversion material, and the green light is eliminated by a green blocking material and thus only the red light is mixed with the red light from an original light source, leading to high light-emitting efficiency and color coordinate values.

In one embodiment, the green filter comprises a second color conversion material and a red blocking material. The second color conversion may be composed of the same material as the first color conversion material for converting blue light from a light-emitting source into green light and red light. In an embodiment, a coumarin derivative such as 3-(2′-benzothiazolyl)-7-diethylaminocoumarin (hereinafter, referred to as coumarin 6), or 3-(2′-benzoimidazolyl)-7-N,N-diethylaminocoumarin (hereinafter, referred to as coumarin 7), Alq3, or inorganic pigments, or organic pigments with fluorescence may be used as a fluorescent pigment of the second color conversion material.

In one embodiment, the red blocking material, which is formed abutting the first color conversion material, is composed of a pigment with transmittance of under 30% in the wavelength ranging from 550 nm to 750 nm and over 60% in the wavelength ranging from 400 nm to 530 nm, or a material in which the pigment is dissolved or dispersed into a binder resin. In an embodiment, if the red blocking material is composed of only a pigment for blocking red color, it is more easily manufactured.FIG. 6is a graph illustrating a transmission spectrum of a red blocking material according to an embodiment of the invention.

In one embodiment the green filter is configured so that the second color conversion material and red blocking material constitute two different layers. In another embodiment, the second color conversion material and red blocking material are provided as a single mixed layer.

In an embodiment when the blue light passes through the green filter, it is converted into green light and red light by the second color conversion material, and the converted red light and the red light from the light source are eliminated by a red blocking material, and thus only the green light remains.

In one embodiment, a blue filter comprises a red blocking material for blocking the red light from a light-emitting source. In an embodiment, cyanine series pigments, copper phthalocyanine series pigments, indanthrone series pigments, dioxazine series pigments, or mixtures thereof may be used as a pigment for the blue filter. When radiated light passes through the blue filter, red light is blocked by the red blocking material, and only blue light remains.

In one embodiment, the color filter array may be manufactured by coating a black matrix on a transparent substrate, forming a black matrix pattern along the location where color filters with each color will be coated, and coating and patterning the color filters sequentially with each color in accordance with the pattern.

A flat panel display device using a color filter array according to an embodiment of the invention will be described below in more detail, in which the above-mentioned color filter array is applied to an organic light-emitting display device, which is one example of the flat display devices. However, it would be understood by those skilled in the art that the green filter may also be applied to a variety of display devices other than the organic light-emitting display devices such as liquid crystal display devices.

FIG. 7is a sectional view illustrating a bottom emitting organic light-emitting display device to which a color filter array is applied according to an embodiment of the invention. According toFIG. 7, an organic light-emitting display device comprises a substrate100, a first electrode110, an organic light-emitting layer120, a second electrode130, and a color filter array160.

In an embodiment, a glass or a transparent plastic with excellent transparency, surface flatness, easy-to-handle characteristics, and water proof/resistance may be used as the substrate.

In an embodiment, a general electrode may also be used for the first and second electrodes110,120without any limitation in the invention, and thus the detailed description will be omitted. In one embodiment, for an anode electrode, ITO, IZO, SnO2, or ZnO may be used, and for a cathode electrode, Li, Mg, Al, Al—Li, Ca, Mg—In, Mg—Ag, etc. may be used.

In an embodiment, the organic light-emitting layer120is configured to emit a mixed light of blue light and red light. In this specification, the term “organic light-emitting layer” is used as a concept essentially including a light-emitting layer, and optionally including a hole injection layer, a hole transporting layer, an emissive layer, a hole blocking layer, an electron injection layer, and a electron transport layer. The details relating to components and functions of the respective layers are well known to those skilled in the art, and thus a detailed description will be omitted. Furthermore, while the organic light-emitting layer is generally described as a single layer, it is understood that two or more layers may be used to form the organic light-emitting layer.

The organic light-emitting layer may be configured in a variety of ways. In one embodiment, separate blue and red light-emitting layers may be formed. In another embodiment multiple blue and red light-emitting layers may be provided in a stacked arrangement.

In an embodiment, the material for emitting blue light may be selected from the group consisting of chemical formula 1, 2, 3, 4, 5, 6, 7, 8, 9, and combinations thereof as follows:

In another embodiment, the material for emitting red light may be selected from the group consisting of chemical formula 10, 11, 12, 13, 14, 15 and combinations thereof as follows:

In one embodiment, the light-emitting intensity may be efficiently controlled by mixing the materials in an appropriate ratio and by adjusting the thickness of the light-emitting layer and the ratio of the host and dopant. In an embodiment, the color coordinate values of the mixed light ranges from 0.20 to 0.50 in its X coordinate, and from 0.20 to 0.43 in its Y coordinate.

For the embodiment ofFIG. 7, the color filter array 160 is provided on the surface opposite to the surface on which an organic light-emitting element is formed, and includes a transparent substrate165, a red filter162, a green filter163, and a blue filter164.

In an embodiment, the red filter162comprises a first color conversion layer162acomprising a first color conversion material and a green blocking layer162bcomprising a green blocking material. In one embodiment, the first color conversion material for the first color conversion layer162ais made of a material for converting blue light from the organic light-emitting layer120into green light and a small amount of red light, with the wavelength of the converted light ranging from 450 nm to 630 nm, which includes the green region ranging from 450 nm to 610 nm. and a small amount of the red region ranging from 610 to 630 nm, as described above.

In one embodiment, the material of the first color conversion material may be made of both a fluorescent pigment and a binder resin or only a fluorescent pigment. In an embodiment, the fluorescent pigment may be, for example, a coumarin derivative such as 3-(2′-benzothiazolyl)-7-diethylaminocoumarin (hereinafter, referred to as coumarin 6), or 3-(2′-benzoimidazolyl)-7-N,N-diethylaminocoumarin (hereinafter, referred to as coumarin 7), inorganic pigments with fluorescence, or organic pigments with fluorescence.

In an embodiment, the first color conversion layer162amay be formed by forming a film of a color conversion resin composition on the substrate to a desired thickness. In one embodiment, the film-forming method may include spin coating, printing, coating, and the like. In an embodiment, a patterning method may be used. In one embodiment, the thickness of the film is in the range of 1 to 30 μm. If the film is less than 1 μm in thickness, the color conversion is not smooth, and if it is more than 30 μm, it becomes difficult to perform the lithography.

In an embodiment, the green blocking layer162b, which is formed abutting the first color conversion material162a, comprises a red pigment with a transmittance of over 50% in the wavelength ranging from 600 nm to 780 nm, or a material in which the pigment is dissolved or dispersed into a binder resin.

In one embodiment, the green blocking layer162bmay be created by forming a film on the first color conversion layer162ato a desired thickness. In an embodiment, the film-forming method may include spin coating, roll coating, bar coating, casting, patterning, and the like. In one embodiment, lithography methods and screen printing methods may be used for patterning after forming the film. In an embodiment, the green blocking layer162bmay be formed in the range of 0.5 to 5 μm in thickness. It is difficult to adjust transparency if the thickness is less than 0.5 μm, and difficult to perform lithography if the thickness is more than 5 μm. In another embodiment, the thickness is in the range of 1 to 2 μm.

In one embodiment, blue light, which passes through the red filter162, is converted to green light and red light by the first color conversion layer162a, and the green light is eliminated by a green blocking layer162band thus only the red light from the color conversion layer162amixed with the red light from the light-emitting source are produced, leading to high light-emitting efficiency and color coordinate values.

In an embodiment, the green filter163comprises a second color conversion layer163amade of a second color conversion material, and a red blocking layer163bmade of a red blocking material. In an embodiment, the second color conversion material comprises a material that may be the same as that of the first color conversion material for converting blue light from a light-emitting source into green light and red light. In one embodiment, the fluorescent pigment of the color conversion material may employ a coumarin derivative such as 3-(2′-benzothiazolyl)-7-diethylaminocoumarin (hereinafter, referred to as coumarin 6), or 3-(2′-benzoimidazolyl)-7-N,N-diethylaminocoumarin (hereinafter, referred to as coumarin 7), Alq3, inorganic pigments with fluorescence, or organic pigments with fluorescence.

In one embodiment, the red blocking layer163b, which is formed abutting the second color conversion material163a, comprises a pigment with a transmittance under 30% in the wavelength ranging from 550 nm to 750 nm and over 60% in the wavelength ranging from 400 nm to 530 nm, or a material in which the pigment is dissolved or dispersed into a binder resin. In an embodiment, it is easier to manufacture the red blocking material163bsince it is composed of only the pigment for blocking red light.

In one embodiment, where the blue light passes through the green filter163, it is converted into green light and red light by the second color conversion layer163a, and the red light from the color conversion layer and the red light from the light-emitting source are eliminated by a red blocking layer163b, and thus only the green light remains.

In an embodiment, a blue filter164comprises a red blocking material for blocking the red wavelength light from a light-emitting source. In an embodiment, cyanine series pigments, copper phthalocyanine series pigments, indanthrone series pigments, dioxazine series of pigments, or mixtures thereof may be used as a pigment for the blue filter164. In an embodiment, when light passes through the blue filter164, red light is blocked by the red blocking material, and only blue light remains.

Other optional components may be included with the organic light-emitting display device according to other embodiments include, for example, a buffer layer150, and a black matrix161, and similar components which are well known may be incorporated in various embodiments by those skilled in the art, and thus the detailed description will be omitted for convenience.

In one embodiment, any one of the respective color filters may be formed as a single layer with a color conversion material and a blocking material mixed, as described above. In an embodiment, the thickness of such a single mixed layer is in the range of 1 to 30 μm. If the film is less than 1 μm in thickness, the color conversion is not smooth, and if it is more than 30 μm, it becomes difficult to perform the lithography.

FIG. 8is a sectional view illustrating a top emitting organic light-emitting display device to which a color filter is applied according to the invention. According to the embodiment as shown inFIG. 8, an organic light-emitting display device comprises a substrate200, a first electrode210, an organic light-emitting layer220, a second electrode230, and a color filter array260. An optional buffer layer250may be provided between the second electrode230and the color filter array260.

For this embodiment, the color filter array260is formed on the side of the second electrode230rather than on the side of the substrate200. In one embodiment, an organic light-emitting display device may be manufactured by adjoining the color filter array260to the substrate surface formed with organic light-emitting elements.

The color filter array of this embodiment includes a red filter262, a green filter263, a blue filter264, and an optional black matrix261. The red filter262comprises a first color conversion layer262aand a green blocking layer262bas described above and the green filter263comprises a second color conversion layer263aand a red blocking layer263bas described above. A transparent substrate265protects the color filters.

In an embodiment, it will be understood by those skilled in the art that the color filter array260may be formed with an additive layer easily combined thereto such as a flattened layer.

As illustrated above, a color filter array according to the invention may be applied to either the top surface of the light-emitting structure or the bottom surface light-emitting structure to form top or bottom-emitting structures. However, the color filter array may also be applied to both surfaces of the light-emitting structure to form a dual-emitting structure.

A manufacturing method according to an embodiment of the invention will be described below with reference toFIG. 7, in which a color conversion material and a color blocking material, respectively, are configured in separate layers. The effect of the color filter array according to the invention manufactured by the method will also be described.

First, a black matrix161pattern is formed on a transparent substrate165and then each of the three color filters162,163,164is coated on the transparent substrate165. For first color conversion layer162aa mixture of 25 mg of coumarin 6 and 2.5 g of PVB (polyvinylbutyral) is dissolved into 7.5 g of (ethyl cellusolve), and is coated on a red pixel region to a thickness less than 10 μm according to the pattern and then dried at 80° C. for a half hour. Then, a green blocking layer162bis coated on the first color conversion layer and dried at 80° C. for two minutes and patterned, thus forming a red filter162.

In an embodiment, a second color conversion layer163ais formed in a green pixel region by the same process as was used for the red filter, and a red blocking layer163bis coated thereon and patterned, thus forming a green filter163. In an embodiment, for the blue filter164, only a red blocking layer is formed in a blue pixel region without separate color conversion material.

FIG. 9is a graph illustrating the light-emitting spectrum of light radiating from a blue light and red light source and passing through the above-mentioned red filter according to an embodiment of the invention, andFIG. 10is a graph illustrating the light-emitting spectrum of light passing through a red filter according to a general manufacturing method from the same light source as that inFIG. 9. A comparison ofFIG. 10andFIG. 9shows the red filter according to the invention transmits little blue wavelength light compared to the general red filter, and has a higher intensity of red wavelength light.

Table 1 compares color coordinate values and light-emitting efficiency of the red filter manufactured by the above-mentioned manufacturing methods and the general red filter according to an embodiment where a mixed light of red and blue light has a color coordinate value of (0.34, 0.38) and an efficiency of 19 cd/A.

Color coordinate values of a red filter according to an embodiment of the invention are (0.67, 0.32), which may provide improved red light emission compared to the color coordinate values (0.65, 0.31) of the general red filter, as shown by Table 1. In addition, the light-emitting efficiency for a red filter of the present invention is highly improved compared to a general red filter.

FIG. 11is a graph illustrating a light-emitting spectrum radiating from a mixed light source of blue light and red light passing through the above-mentioned green filter according to an embodiment of the invention, andFIG. 12is a graph illustrating the light-emitting spectrum of light passing through a green filter according to a general manufacturing method from the same light source as that inFIG. 11. A comparison ofFIG. 12andFIG. 11shows the green filter according to an embodiment of the invention has higher intensity in higher green wavelength regions than the case where the general green filter is applied.

Table 2 shows the comparison of color coordinate values and light-emitting efficiency of the green filter manufactured by the above-mentioned manufacturing method according to an embodiment of the invention, and the general green filter, where a mixed light source of red light and blue light with color coordinate values (0.32, 0.41).

Color coordinate values of a green filter according to an embodiment of the invention are (0.22, 0.67), which provides an improved red light emission compared to the color coordinate values (0.27, 0.56) of the general green filter as shown in Table 2. In addition, the light-emitting efficiency of 6.5 cd/A for the green filter of the invention is highly improved compared to a general green filter.

Table 3 shows the color coordinate values and light-emitting efficiency of light passing through the red filter and green filter where the color coordinate values and light-emitting efficiency of the mixed light of red and green light are different from those of the above-mentioned embodiment.

TABLE 3Light-emittingefficiency(cd/A)Color coordinatesLight source18(0.34, 0.38)Red light after passing through5.5(0.67, 0.32)the color filtergreen light after passing9.5(0.25, 0.65)through the color filterblue light after passing3.6(0.10, 0.21)through the color filter

FIG. 13is a graph illustrating the color coordinate values of Table 3. It may be seen that a full color reproduction range, which amounts to 74% can be implemented.

In an embodiment, it may be possible to employ the color filter of the invention for any one filter of respective color filters like a red filter. Additionally, one may employ other well known filters for other color filters like the green filter, and vice versa. In addition, variations of material constituting the organic light-emitting layer, the components and thickness of the color conversion layer or the green blocking layer and the like may be easily made by those skilled in the art.

While the invention has particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details can be made therein without departing from the spirit and scope of the appended claims and their equivalents.