Color filter, manufacturing method therefor, and display device comprising same

Abstract

The present invention relates to a color filter to which a Bragg reflection layer is applied, a manufacturing method therefor, and a display device comprising same. According to the present invention, it is possible to provide a color filter having improved light conversion efficiency characteristics by applying a Bragg reflection layer, a manufacturing method therefor, and a display device. According to the present invention, the thickness of a color conversion layer may be reduced by applying a Bragg reflection layer, thereby enabling the provision of a large-sized display panel with enhanced price competitiveness.

Description

Color filter, method of manufacturing the same, and display device including the same

[0001] The present invention relates to a color filter, a method for manufacturing the same, and a display device including the same.

[0002] With the recent development of next-generation display light source technologies such as MicroLEDs and ultra-large, high-resolution displays based on them, the materials technology and display structures applied to these technologies are attracting the attention of many researchers. In particular, there is the highest level of interest in display structures based on color conversion layers containing quantum dots, which facilitate large-area implementation and are advantageous for RGB color reproduction.

[0003] To improve the color reproduction of displays based on color conversion layers containing quantum dots, the quantum dots must possess high light conversion efficiency. Technologies to achieve this include light generation techniques using filters and light recycling techniques using distributed Bragg reflectors. In addition, various other methods are being proposed to improve luminescence stability.

[0004] Among these, Bragg mirrors, which consist of a structure in which layers of materials with different refractive indices are alternately and periodically stacked and where changes in reflectance are induced by the difference in refractive index between the layers, have the advantage of maintaining the chemical and physical stability of the material while exhibiting minimal changes in optical properties over time. Due to these characteristics, Bragg mirrors are receiving significant attention as display light sources based on color conversion layers containing quantum dots. However, Bragg mirrors still face many challenges that need to be addressed due to limitations such as high manufacturing costs and difficulties in large-scale processes.

[0005] For example, a color conversion layer containing quantum dots may be structured to recycle blue light when blue light, which is a light source of the display, is injected into the pixel area by inserting a low-refractive-index material with a refractive index in the range of 1 to 1.4 into the pixel area. In conventional structures, the thickness of the color conversion layer containing quantum dots must be formed relatively thick in order to ensure that the blue light injected from the light source is absorbed by more than 90% by the quantum dots to exhibit high light conversion efficiency. This leads to an increase in the amount of quantum dots required, and consequently, a problem arises in which the manufacturing cost of the display panel increases.

[0006] Meanwhile, when a Bragg reflection layer is formed within the pixel area using a Bragg reflector, high light conversion efficiency can be secured while maintaining the thickness of the color conversion layer containing the quantum dots relatively thin, which has the advantage of lowering the manufacturing cost of the display panel.

[0007] However, to apply Bragg mirrors to large display panels, it is necessary to perform glass deposition and etching processes on the front surface of a large substrate while precisely controlling the thickness of the Bragg mirrors in the nanometer range. This can lead to reduced process yield and high equipment investment costs. For these reasons, there are difficulties in applying this technology to large displays, yet no technical solution to fundamentally resolve these issues has been proposed to date.

[0008] The present invention aims to solve the above problems by providing a color filter that enables large-area printing, reduces the thickness of the color conversion layer, and lowers the unit cost of the panel, a method for manufacturing the same, and a display device including the same.

[0009] To solve the above problem, the color filter of the present invention comprises a substrate and a plurality of pixel regions disposed on the substrate, wherein each of the pixel regions includes a first sub-pixel region, a second sub-pixel region, a third sub-pixel region, and a partition disposed on the substrate and surrounding each of the sub-pixel regions. Each of the sub-pixel regions includes a color conversion layer disposed on the substrate, and the first sub-pixel region and the second sub-pixel region include a first Bragg reflection layer between the substrate and the color conversion layer.

[0010] In addition, a second Bragg reflection layer may be further included on top of the color conversion layer of each of the above subpixel regions.

[0011] In addition, the thickness of the color conversion layer may be 0.1 μm to 10 μm.

[0012] Additionally, the color conversion layer of the first subpixel area may include quantum dots that emit red light, and the color conversion layer of the second subpixel area may include quantum dots that emit green light.

[0013] In addition, the interference reflectance of the first Bragg reflective layer may be 50% to 100%.

[0014] In addition, the interference reflectance of the second Bragg reflective layer may be 0% to 50%.

[0015] In addition, the first Bragg reflective layer and the second Bragg reflective layer may be formed by alternately stacking a high refractive index layer and a low refractive index layer.

[0016] In addition, the high refractive index layer may have a refractive index of 1.5 to 4.0, the low refractive index layer may have a refractive index of 1.1 to 3.0, and the high refractive index layer may have a refractive index that is 0.1 or higher than that of the low refractive index layer.

[0017] In addition, the total number of layers of the high refractive index layer and the low refractive index layer in each of the first Bragg reflective layer and the second Bragg reflective layer may be 4 to 40.

[0018] In addition, the first Bragg reflective layer and the second Bragg reflective layer may include micro Bragg reflector flakes.

[0019] In addition, the display device of the present invention may include the color filter.

[0020] In addition, the method for manufacturing a micro Bragg reflector flake according to the present invention comprises the steps of forming a separation layer on a substrate, forming a Bragg reflector on the separation layer, etching the Bragg reflector in a direction perpendicular to the substrate to form a micro Bragg reflector, and separating the micro Bragg reflector to form a flake.

[0021] In addition, the printing composition of the present invention comprises a microbragg reflector flake and a solvent, wherein the microbragg reflector flake has a width of 50 μm or less, a length of 50 μm or less, and a height of 5 μm or less.

[0022] In addition, the method for manufacturing a color filter according to the present invention is a method for manufacturing a color filter comprising a substrate and a plurality of pixel regions disposed on the substrate, comprising the steps of: forming a first sub-pixel region, a second sub-pixel region, and a third sub-pixel region by installing a partition on the substrate; forming a first Bragg reflective layer by applying a composition comprising micro Bragg reflector flakes to the first sub-pixel region and the second sub-pixel region; and forming a color conversion layer on the substrate within the first Bragg reflective layer and the third sub-pixel region.

[0023] In addition, the method for manufacturing the color filter may further include the step of forming a second Bragg reflection layer on the color conversion layer.

[0024] According to the present invention, a color filter capable of large-area printing, reducing the thickness of the color conversion layer, and lowering the unit cost of the panel, a method for manufacturing the same, and a display device including the same can be provided.

[0025] FIG. 1 is a schematic diagram showing a color filter having a first Bragg reflection layer formed in a first subpixel area and a second subpixel area of ​​the present invention.

[0026] FIG. 2 is a schematic diagram showing a method for manufacturing a micro Bragg reflector flake according to an embodiment of the present invention.

[0027] FIG. 3 is a photograph taken with an optical microscope of a micro Bragg reflector flake formed by alternately stacking Si3N4 as a high refractive index layer and SiO2 as a low refractive index layer seven times, according to an embodiment of the present invention.

[0028] Figures 4 (a) and (b) are optical microscope images showing micro Bragg reflector flakes placed in a space within an epoxy resin barrier through an electrohydrodynamic (EHD) inkjet printing process.

[0029] FIG. 5 is a schematic diagram showing a color filter having a second Bragg reflection layer additionally formed on top of the color conversion layer of each subpixel area of ​​the present invention.

[0030] Figure 6 is a graph showing the results of a wavelength-dependent reflectance simulation according to the total number of stacked layers when low-refractive-index layers and high-refractive-index layers are alternately stacked using the Essential Macleod (Thin Film Center Inc, Core) simulator according to an embodiment of the present invention.

[0031] Figure 7(a) is a graph showing the comparison of simulation results for the reflectance (%) of light for a micro Bragg reflector having a total of 10 layers stacked alternately 5 times with the thickness of the high refractive index layer set to 13 nm and the thickness of the low refractive index layer set to 138 nm according to an embodiment of the present invention, and a total of 14 layers stacked alternately 7 times with the thickness of the high refractive index layer set to 27 nm and the thickness of the low refractive index layer set to 111 nm.

[0032] Figure 7(b) is a graph showing the comparison of simulation results for light reflectance (%) for a total of 6-layer structure and a total of 14-layer structure, in which the thickness of the high-refractive-index layer is set to 27 nm and the thickness of the low-refractive-index layer is set to 111 nm, respectively, according to another embodiment of the present invention, and then the two layers are alternately stacked 3 times and 7 times, respectively.

[0033] FIGS. 8(a) and (b) are scanning electron microscope top views of a micro Bragg mirror formed by alternately stacking a low refractive index layer and a high refractive index layer on a Si wafer seven times according to an embodiment of the present invention, and FIGS. 8(c) and (d) are scanning electron microscope side views of the micro Bragg mirror.

[0034] Figure 9(a) is a photograph showing microbragg reflector flakes formed by alternately stacking a low-refractive-index layer and a high-refractive-index layer 7 times in 20 ml of ethanol and dispersed in a 50 ml conical tube, and Figure 9(b) is a photograph taken with an optical microscope.

[0035] FIG. 10 is a graph showing the measurement results of emission spectra for color filters with and without a micro Bragg reflector, according to an embodiment and a comparative example of the present invention.

[0036] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated and described in the drawings. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0037] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be named the first component, and similarly, the first component may be named the second component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0038] In the description of the embodiments, the statement that each layer (film), region, pattern, or structure is formed "on" or "under" the substrate, each layer (film), region, or pattern includes both direct formation and formation through another layer. The reference for the "on" or "under" of each layer is described based on the drawings. Additionally, the thickness or size of each layer (film), region, pattern, or structure in the drawings may be modified for clarity and convenience of explanation, and therefore does not fully reflect the actual size.

[0039] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this invention, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0040] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this invention.

[0041] The present invention will be explained in more detail below through embodiments according to the present invention, but the scope of the present invention is not limited by the embodiments presented below.

[0042] The present invention relates to a color filter comprising a substrate; and a plurality of pixel regions disposed on the substrate, wherein each of the pixel regions comprises a first sub-pixel region, a second sub-pixel region, a third sub-pixel region, and a partition wall disposed on the substrate and surrounding each of the sub-pixel regions, and each of the sub-pixel regions comprises a color conversion layer disposed on the substrate, and the first sub-pixel region and the second sub-pixel region comprise a first Bragg reflection layer between the substrate and the color conversion layer.

[0043] Color filter (100)

[0044] The color filter of the present invention comprises a substrate and a plurality of pixel regions disposed on the substrate, wherein each of the pixel regions comprises a first sub-pixel region, a second sub-pixel region, a third sub-pixel region, and a partition disposed on the substrate and surrounding each of the sub-pixel regions.

[0045] FIG. 1 is a schematic diagram showing a color filter (100) having a first Bragg reflection layer (610) applied to a first subpixel area (410) and a second subpixel area (420) according to an embodiment of the present invention. The color filter (100) includes a plurality of pixel areas (400) on a substrate (200).

[0046] The substrate (200) serves to support and fix components such as a pixel area (400) and a partition (300). The substrate (200) is not particularly limited and may include, for example, any one of polyimide, polydimethylsiloxane, polyethylene terephthalate, epoxy, and silicon oxide (SiO2), and may use any one of an ultra-thin glass substrate, a glass substrate, a silicon wafer, and a sapphire substrate. Specifically, it may be a glass substrate. In addition, the substrate (200) may be a flexible substrate made of various flexible materials. The thickness of the substrate (200) may be 300 μm to 3000 μm.

[0047] The pixel area (400) is an area that displays images and characters on the screen of a display element by receiving light emitted from a light source (not shown) and implementing red, green, and blue, and a plurality of pixel areas (400) are arranged on a substrate (200).

[0048] Each of the above pixel regions (400) includes a plurality of sub-pixel regions (410, 420, 430) that emit red, green, and blue light. For example, a sub-pixel region emitting red light may be called a first sub-pixel region (410), a sub-pixel region emitting green light may be called a second sub-pixel region (420), and a sub-pixel region emitting blue light may be called a third sub-pixel region (430). The sub-pixel regions (410, 420, 430) of the present invention may have a length of 10 μm to 250 μm in a horizontal direction parallel to the surface of the substrate (200), and may have a length of 10 μm to 250 μm in a vertical direction parallel to the surface of the substrate (200) and perpendicular to the horizontal direction.

[0049] Each of the above subpixel areas (410, 420, 430) is surrounded by a partition (300), and each subpixel area (410, 420, 430) can be separated by the partition (300). The partition (300) of the present invention is formed to have a position higher than the position of the second Bragg reflection layer (620) formed on the color conversion layer (411, 421, 431) starting from the substrate, and can serve to block optical crosstalk, which is a phenomenon in which light emitted from each subpixel area (410, 420, 430) overlaps, and can also serve to prevent the printing composition or ink from mixing into adjacent subpixels during the manufacturing process of the color filter (100), and to ensure that it is applied and coated within the subpixel area to be printed. The partition wall (300) of the present invention can be manufactured from any one of polyimide, epoxy resin, photoresist, and black matrix, and specifically can be manufactured from photoresist. The height of the partition wall of the present invention may be 10 μm to 50 μm in a direction perpendicular to the plane in which subpixel regions (410, 420, 430) are arranged from the substrate.

[0050] Each subpixel area (410, 420, 430) may have a color conversion layer (411, 421, 431) on the substrate (200), and the color conversion layer (411, 421) may be placed overlapping with a first Bragg reflection layer (610) placed on the substrate (200).

[0051] Light source (midoshi)

[0052] The light source of the present invention is not particularly limited and may be, for example, a light-emitting diode (LED), an organic light-emitting diode (OLED), or a cold cathode fluorescent lamp (CCFL). The luminance of the light source of the present invention is 100 cd / m². 2 Up to 5000 cd / m 2 It may be. In addition, the wavelength range of the light source may be 350 nm to 470 nm, and specifically, may be 360 ​​nm to 410 nm and / or 440 nm to 470 nm. The light source of the present invention has a wavelength of 1000 cd / m² on the screen of a display element. 2 As long as the brightness above can be displayed, the color conversion layer (411, 421, 431) may be placed on the upper side, the lower side, or the side of the color conversion layer (411, 421, 431), etc., respectively or simultaneously.

[0053] Bragg reflective layer (610, 620)

[0054] The Bragg reflective layer (610, 620) of the present invention may include micro-Bragg reflector flakes. Additionally, the micro-Bragg reflector flakes may have a micro-Bragg reflector structure configured to selectively reflect light of a specific wavelength by alternating and periodically stacking material layers with different refractive indices between each layer. The Bragg reflective layer (610, 620) of the present invention may include a first Bragg reflective layer (610) disposed between a substrate (200) and a color conversion layer (411, 421, 431), and a second Bragg reflective layer (620) disposed superimposed on the color conversion layer (411, 421, 431).

[0055] FIGS. 2(a) to (g) are schematic diagrams illustrating a method for manufacturing a microbragg reflector flake according to an embodiment of the present invention. FIG. 2(a) shows the step of preparing a substrate (200) to form a microbragg reflector flake, FIG. 2(b) shows the step of forming a microbragg reflector flake on the substrate (200) and then forming a separation layer that serves to separate the microbragg reflector flake from the substrate (200), and FIG. 2(c) shows the step of forming a Bragg reflector by alternately stacking material layers with different refractive indices on the separation layer. Additionally, FIG. 2(d) shows a step of forming a masking pattern to form micro-Bragg reflector flakes on the Bragg reflector, FIG. 2(e) shows a step of forming a micro-Bragg reflector by etching the Bragg reflector in a direction perpendicular to the substrate (200) using the masking pattern, FIG. 2(f) and FIG. 2(g) show a step of forming micro-Bragg reflector flakes by removing the separation layer from the substrate (200) and the micro-Bragg reflector.

[0056] The method for manufacturing a micro Bragg reflector flake of the present invention first includes the step of preparing a substrate (200) that has been cleaned and dried as shown in (a) of FIG. 2.

[0057] Subsequently, a separation layer is formed on the substrate (200) as shown in FIG. 2 (b). The material of the separation layer is not particularly limited, and any material that can be easily removed from the substrate and the microbragg reflector flakes by wet etching or dry etching can be used. Preferably, it is desirable to use a metal that has a high selectivity ratio for the microbragg reflector during the etching process, so that damage to the microbragg reflector caused by etching does not occur. For example, Al, Cu, Ni, or Mo, etc., can be used as the material forming the separation layer, and specifically, Al can be used as the separation layer material.

[0058] The above separation layer can be formed on a substrate by various methods such as chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), plating process, or printing process. The formed separation layer can then be easily removed from the substrate (200) and the microbragg reflector flakes by wet etching or dry etching.

[0059] In the present invention, the thickness of the separation layer is a thickness that can stably separate the microbragg reflector flakes from the substrate (200), and, for example, may be 300 nm to 1000 nm.

[0060] Next, the method may include the step of forming a Bragg mirror on the separation layer as illustrated in (c) of FIG. 2. The Bragg mirror may have a structure in which a high refractive index layer (631) and a low refractive index layer (632) are alternately stacked. Additionally, the method may include a structure in which a Bragg layer (633), comprising a pair of high refractive index layers (631) and low refractive index layers (632), is repeatedly stacked 2 to 20 times.

[0061] Additionally, the respective thicknesses of the high-refractive-index layer (631) and the low-refractive-index layer (632) included in the Bragg layer (633) may be 1 nm to 500 nm, respectively, depending on the center position of the target reflection wavelength and the full width at half maximum (FWHM) of the reflection spectrum. The respective thicknesses of the high-refractive-index layer (631) and the low-refractive-index layer (632) may be adjusted so that the optical thickness satisfies the 1 / 4 wavelength condition for the design reflection wavelength, thereby enabling high reflectivity due to constructive interference in a specific wavelength region. Furthermore, the width of the reflection band and the shape of the reflection spectrum may be controlled according to the combination of the thicknesses of the high-refractive-index layer (631) and the low-refractive-index layer (632) and the number of repeated stackings of the Bragg layer (633). In this way, by setting the thickness of each of the high refractive index layer (631) and the low refractive index layer (632) to a range of 1 nm to 500 nm, the optical characteristics of the target wavelength can be freely designed during the manufacturing process, thereby ensuring stable optical performance.

[0062] According to an embodiment of the present invention, when a first Bragg reflection layer (610) is formed on a substrate (200), the first Bragg reflection layer (610) may have a structure that repeats the order of a high refractive index layer (631) - a low refractive index layer (632) - a high refractive index layer (631) - a low refractive index layer (632) starting from the position closest to the substrate (200), or may have a structure that repeats the order of a low refractive index layer (632) - a high refractive index layer (631) - a low refractive index layer (632) - a high refractive index layer (631) starting from the position closest to the substrate (200).

[0063] Additionally, as described below, when a second Bragg reflection layer (620) is formed on a color conversion layer (411, 421, 431) according to an embodiment of the present invention, the second Bragg reflection layer (620) may have a structure that repeats the order of high refractive index layer (631) - low refractive index layer (632) - high refractive index layer (631) - low refractive index layer (632) starting from the position closest to the color conversion layer (411, 421, 431), or may have a structure that repeats the order of low refractive index layer (632) - high refractive index layer (631) - low refractive index layer (632) - high refractive index layer (631) starting from the position closest to the color conversion layer (411, 421, 431).

[0064] In the present invention, the refractive index of the first Bragg reflective layer (610) can have the same refractive index characteristics even if the stacking order is different as described above, provided that the type of material included in each of the high refractive index layer (631) and the low refractive index layer (632), the thickness of each layer, and the number of stacking layers are the same. Similarly, the second Bragg reflective layer (620) can also have the same refractive index characteristics even if the stacking order is different, provided that the type of material included in each of the high refractive index layer (631) and the low refractive index layer (632), the thickness of each layer, and the number of stacking layers are the same.

[0065] In the present invention, the refractive index of the high refractive index layer (631) is 1.5 to 4.0, and the refractive index of the low refractive index layer (632) is 1.1 to 3.0, and the refractive index of the high refractive index layer (631) may be 0.1 or higher than the refractive index of the low refractive index layer (632).

[0066] In the present invention, if the refractive index of the high refractive index layer (631) is less than 1.5, the difference in refractive index with the low refractive index layer (632) is not sufficiently secured, so light reflection, light interference, and light confinement effects at the interlayer interface may be reduced, and there is a concern that the light path control ability or light efficiency improvement effect required in a multilayer structure may not be sufficiently manifested. On the other hand, if the refractive index of the high refractive index layer (631) exceeds 4.0, not only is the range of applicable materials selected limited, but problems such as increased light absorption of the material itself, increased difficulty in the manufacturing process, and reduced uniformity of the thin film may occur.

[0067] Additionally, if the refractive index of the low refractive index layer (632) is less than 1.1, it may have a refractive index close to that of the air layer, which may result in reduced stability of thin film formation or a lack of mechanical strength due to the porous structure, and the applicable materials may also be limited. If the refractive index of the low refractive index layer (632) exceeds 3.0, the difference in refractive index with the high refractive index layer (631) decreases, and there is a possibility that the light reflectance control, light interference effect, and light path control effect required in the multilayer structure may not be sufficiently expressed.

[0068] Accordingly, by setting the refractive index of the high refractive index layer (631) to a range of 1.5 to 4.0 and the refractive index of the low refractive index layer (632) to a range of 1.1 to 3.0, the difference in refractive index between layers can be stably maintained while simultaneously ensuring physical stability of the thin film and suitability for the manufacturing process.

[0069] The high refractive index layer (631) of the present invention may include a dielectric material having a higher refractive index than the material included in the low refractive index layer (632), and the low refractive index layer (632) may include a dielectric material having a lower refractive index than the material included in the high refractive index layer (631). At this time, if the difference between the refractive index of the material included in the high refractive index layer (631) and the refractive index of the material included in the low refractive index layer (632) is 0.1 or more, and the refractive index of the material included in the high refractive index layer (631) is 1.5 to 4.0 and the refractive index of the material included in the low refractive index layer (632) is 1.1 to 3.0, then the dielectric material included in each of the high refractive index layer (631) and the low refractive index layer (632) is not particularly limited. For example, TiO2 (refractive index: 2.4) can be used for the high refractive index layer (631) and Al2O3 (refractive index: 1.7) can be used for the low refractive index layer (632). Additionally, if Al2O3 (refractive index: 1.7) is used for the high refractive index layer (631), SiO2 (refractive index: 1.4) can be used for the low refractive index layer (632).

[0070] If the difference between the refractive index of the material included in the high-refractive-index layer (631) and the refractive index of the material included in the low-refractive-index layer (632) is less than 0.1, the interlayer refractive index contrast in the Bragg reflection structure is not sufficiently secured, which may result in a decrease in reflectance in the target wavelength region or an increase in the full width at half maximum of the reflection spectrum, thereby reducing wavelength selectivity. As a result, the optical efficiency of the Bragg mirror is reduced, and consequently, problems such as reduced color purity and increased light loss may occur.

[0071] Next, as illustrated in (d) of FIG. 2, the method may include the step of forming a masking pattern for forming micro-Bragg reflector flakes on the Bragg reflector. The process of forming the masking pattern is not particularly limited and may be any process capable of forming a masking pattern for patterning micro-Bragg reflectors on the Bragg reflector, such as a photoresist process, an imprinting process, or a screen printing process.

[0072] Next, as illustrated in 2(e), the method may include the step of forming a micro-Bragg mirror by etching the Bragg mirror in a direction perpendicular to the substrate (200) through an etching process. Specifically, the etching process may include a dry etching process and a wet etching process. Specifically, when performing a dry etching process to form a micro-Bragg mirror, for example, tetrafluoromethane gas may be used, and the etching ratio between the material contained in the high refractive index layer (631) and the material contained in the low refractive index layer (632) may be 1:1 to 1:2, and the etching ratio between the separation layer and the micro-Bragg mirror may be 1:10 to 1:100. Additionally, when performing a wet etching process, for example, a hydrogen fluoride solution may be used, and the etching ratio between the material contained in the high refractive index layer (631) and the material contained in the low refractive index layer (632) may be 1:1 to 1:1.5, and the etching ratio between the separation layer and the micro Bragg reflector may be 1:100 to 1:1000.

[0073] After the etching process of the Bragg reflective layer is completed, a micro Bragg reflector formed on the separation layer can be obtained by removing the masking pattern using a masking pattern remover such as a photoresist removal solution (PR remover) or an acetone solution.

[0074] Next, as illustrated in FIG. 2 (f), the separation layer can be removed from the substrate (200) and the microbragg reflector to finally obtain a microbragg reflector flake as shown in FIG. 2 (g). The separation layer can be removed through a wet etching process. The etching solution used for the above wet etching may include at least one of phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, hypophosphorous acid, carbonic acid, boric acid, hydrofluoric acid, sulfamic acid, lactic acid, malonic acid, succinic acid, glycolic acid, oxalic acid, oxaloacetic acid, fumaric acid, malic acid, acetic acid, butyric acid, palmitic acid, tartaric acid, ascorbic acid, uric acid, sulfonic acid, sulfinic acid, formic acid, citric acid, isocitric acid, and alpha-ketoglutaric acid, and / or at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, tetramethylammonium hydroxide, ammonium hydroxide, magnesium hydroxide, barium hydroxide, aluminum hydroxide, an aqueous solution of sodium bicarbonate and alkyl amines, and an aqueous solution of sodium carbonate, and the selectivity ratio between the microbragg reflector flake and the separation layer may be 1:100 to 1:1000.

[0075] For example, FIG. 3 shows a microbragg reflector flake formed with a total of 14 layers by alternately stacking 7 pairs of Si3N4 with a thickness of 27 nm as a high refractive index layer (631) and SiO2 with a thickness of 111 nm as a low refractive index layer (632).

[0076] In the present invention, the microbragg reflector flake may have a horizontal length of 50 μm or less, a vertical length of 50 μm or less, and a height of 5 μm or less. At this time, the lower limits of the horizontal length, vertical length, and height of the microbragg reflector flake of the present invention are not particularly limited, but the horizontal length may be 1 μm or more, the vertical length may be 1 μm or more, and the height may be 0.2 μm or more.

[0077] In the present invention, the width of the microbragg reflector flake refers to the maximum length of the microbragg reflector flake measured in a direction parallel to the surface of the substrate (200) based on when the microbragg reflector flake forms a Bragg reflective layer. Additionally, the height refers to the maximum length measured in a direction perpendicular to the width direction while being parallel to the surface of the substrate (200), and the height refers to the length of the microbragg reflector flake measured in a direction perpendicular to the surface of the substrate (200). If the width and height of the microbragg reflector flake each exceed 50 μm or the height exceeds 5 μm, the dispersibility within the ink containing the microbragg reflector flake may be reduced. As a result, it may be difficult to uniformly form the first Bragg reflective layer (610) and / or the second Bragg reflective layer (620) within the subpixel areas (410, 420, 430) through the printing process, and a problem may occur that causes the nozzle of the inkjet printing head to clog.

[0078] The first Bragg reflection layer (610) of the present invention may be placed between the substrate (200) and the color conversion layer (411, 421) in the first subpixel area (410) and the second subpixel area (420). On the other hand, the first Bragg reflection layer (610) may not be placed between the substrate (200) and the color conversion layer (431) in the third subpixel area (430). By not forming the first Bragg reflection layer (610) between the substrate (200) and the color conversion layer (431) in the third subpixel area (430), the optical performance of the display device can be maintained while reducing the number of processes to improve productivity, and at the same time, the amount of material used can be reduced to achieve a material cost reduction effect.

[0079] In the present invention, a composition containing the micro-Bragg reflector flakes can be applied to each of the first sub-pixel area (410) and the second sub-pixel area (420) on the substrate (200) to form a first Bragg reflective layer (610), and this application process may be any one of inkjet printing, screen printing, and fluid self-assembly printing. Specifically, it can be used in an inkjet printing process. The inkjet printing process is advantageous for manufacturing high-resolution display devices because it can spray the composition containing the micro-Bragg reflector flakes in the required amount at an accurate location, and it can be economical when using expensive compositions (ink).

[0080] In order to form a first Bragg reflection layer (610) in a subpixel using the above-mentioned micro Bragg reflector flakes, a surface modification process through N2 or Ar plasma treatment may be included for the partition (300) and substrate (200) constituting the pixel area (400). By the above-mentioned N2 or Ar plasma treatment process, OH groups are introduced into the oxide layer formed on the surface of the partition (300) and substrate (200), and accordingly, the surface of the substrate (200) within the subpixel area (410, 420) is modified to be hydrophilic so that hydrogen bonds can be formed.

[0081] Subsequently, by performing heat treatment, the hydrogen bond is converted into a covalent bond, and accordingly, bonding energy between the micro Bragg reflector flake and the substrate (200) can be formed.

[0082] As a result, in the first subpixel area (410) and the second subpixel area (420), a stable covalent bond is formed between the substrate (200) with surface bonding activated and the microbragg reflector flake, so that the microbragg reflector flake can be stably placed in the subpixel areas (410, 420).

[0083] Figures 4(a) and 4(b) are optical microscope images showing a state in which a micro Bragg reflector flake manufactured according to an embodiment of the present invention is placed within a space surrounded by an epoxy resin partition (300) formed by a photolithography process using electrohydrodynamic (EHD) inkjet printing technology.

[0084] In FIG. 4 (a) and (b), a partition (300) was formed through a photolithography process, and then a surface improvement process was performed through Ar plasma treatment. Then, micro Bragg reflector flakes were placed in the space within the partition (300) through electrohydrodynamic inkjet printing.

[0085] The partition wall (300) shown in FIG. 4(a) has a height of 10 μm, and the space enclosed by the partition wall has a width and length of 80 μm and 80 μm, respectively. Additionally, the width and length of the microbragg reflector flake placed within the partition wall (300) are 10 μm and 10 μm, respectively, and the height is 0.966 μm. The microbragg reflector flake has a stacked structure in which a high refractive index layer (631) of 27 nm thick Si3N4 and a low refractive index layer (632) of 111 nm thick SiO2 are alternately repeated 7 times.

[0086] The partition wall (300) shown in FIG. 4(b) has a width and length of 20 μm and 20 μm, respectively, and a height of 10 μm. Additionally, the width and length of the microbragg reflector flake placed within the partition wall (300) are 10 μm and 10 μm, respectively, and the height is 0.966 μm. The microbragg reflector flake has a stacked structure in which a high refractive index layer (631) of 27 nm thick Si3N4 and a low refractive index layer (632) of 111 nm thick SiO2 are alternately repeated 7 times.

[0087] In the present invention, as shown in FIG. 5, after forming a first Bragg reflective layer (610) in a first subpixel area (410) and a second subpixel area (420), a second Bragg reflective layer (620) may be further formed on a color conversion layer (411, 421, 431). The second Bragg reflective layer (620) may be formed by placing micro Bragg reflector flakes on the color conversion layer (411, 421, 431) through an electrohydrodynamic inkjet printing process. The process method may include the same method and materials as the method and materials used to form the first Bragg reflective layer (610), except that a surface improvement process through N2 or Ar plasma treatment and a printing process to form the second Bragg reflective layer (620) are also performed on a third subpixel area (430).

[0088] The printing composition for forming the first Bragg reflective layer (610) and the second Bragg reflective layer (620) of the present invention may include the micro Bragg reflector flakes, may include a dispersion as a solvent, and may further include additives that improve or maintain the quality of the composition.

[0089] Specifically, the printing composition for forming the Bragg reflective layer (610, 620) in the present invention may include the micro Bragg reflector flakes. The micro Bragg reflector flakes may be included at a concentration of 0.01% to 5% by weight based on the total weight of the composition. If the concentration of the micro Bragg reflector flakes included in the composition is less than 0.01% by weight, the density of the micro Bragg reflector flakes placed within the subpixel area after the printing process is not sufficiently secured, which may result in a decrease in the reflection efficiency of the Bragg reflective layer or an uneven formation of the layer. On the other hand, if the concentration exceeds 5% by weight, the viscosity of the composition may increase excessively or the dispersion stability may decrease, which may result in a decrease in the safety of the printing process, such as nozzle clogging and / or poor ejection.

[0090] In the present invention, the printing composition for forming the Bragg reflective layer (610, 620) may include a hydrophilic solvent as a solvent. Since the micro-Bragg reflector flakes, which are the solute, are composed of inorganic materials, the composition may include a hydrophilic solvent to improve the dispersibility, surface tension, and wettability characteristics of the micro-Bragg reflector flakes on the substrate. For example, the hydrophilic solvent may include water, glycerol, ethylene glycol, 2-pyrrolidone, propylene glycol, N-methyl-2-pyrrolidone, isopropanol, diethylene glycol monobutyl ether, isopropyl alcohol, or a combination thereof. The solvent may be included at a concentration of 60% to 98% by weight based on the total weight of the composition.

[0091] In addition, the printing composition for forming the Bragg reflective layer (610, 620) in the present invention may include surfactants, viscosity modifiers, dispersants, and drying modifiers as additives. Specifically, Triton X-100 or a polyoxyethylene-based surfactant may be included as a surfactant for controlling the surface tension of the composition, and polymer additives and glycol-based compounds may be included as viscosity modifiers that affect the spray stability in the printer head. Polyvinylrolidone or polyethylene glycol may be included as a dispersant to ensure that the micro Bragg reflector flakes are uniformly dispersed in the dispersion and to prevent sedimentation. Glycol ether or dipropylene glycol may be included as a drying modifier. Additionally, to ensure the viscosity, uniformity, and surface tension characteristics of the composition, dipropylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol methyl ether acetate, cyclododecene, or combinations thereof may be included. The above additive may be included at a concentration of 5% by weight or less based on the total weight of the composition.

[0092] The first Bragg reflective layer (610) of the present invention may have an interference reflectance of 50% to 100%. That is, the first Bragg reflective layer (610) may reflect 50% to 100% of incident light at a specific wavelength. Here, the interference reflectance refers to the ratio of the intensity of reflected light in a direction parallel to the direction of incidence to the intensity of incident light incident from a light source in a direction perpendicular to the mirror (intensity of reflected light reflected in a direction parallel to the direction of incidence and / or intensity of incident light incident from a light source in a direction perpendicular to the mirror). Specifically, the first Bragg reflective layer (610) has a structure in which a high refractive index layer (631) and a low refractive index layer (632) are alternately stacked, and the reflectance of the first Bragg reflective layer (610) may be determined according to the difference in refractive index between the high refractive index layer (631) and the low refractive index layer (632) and the number of stacking repetitions. Generally, the greater the difference in refractive index between the high-refractive-index layer (631) and the low-refractive-index layer (632) and / or the greater the number of stacking repetitions, the greater the interference reflectance may be.

[0093] The first Bragg reflective layer (610) has the highest reflectivity at the center wavelength, and light having wavelengths deviating from the designed center wavelength may have low reflectivity due to destructive interference. Fresnel reflection may occur at the interface between the high refractive index layer (631) and the low refractive index layer (632) due to the difference between the refractive index of the high refractive index layer (631) and the refractive index of the low refractive index layer (632). Accordingly, as light emitted from a light source passes through the Bragg reflector, constructive and destructive interference may occur, and by appropriately controlling this through optical design, the Bragg reflector may be able to pass and / or reflect only selective wavelengths. Through this, the first Bragg reflective layer (610) can be designed to selectively reflect or filter specific wavelengths.

[0094] The interference reflectance of the second Bragg reflective layer (620) of the present invention may be 0% to 50%. That is, the second Bragg reflective layer (620) may reflect 0% to 50% of incident light at a specific wavelength and transmit the remaining 0% to 50%. As described above, the interference reflectance of the second Bragg reflective layer (620) at a specific wavelength can be designed by adjusting the difference in refractive index between the high refractive index layer (631) and the low refractive index layer (632) and the number of stacking repetitions.

[0095] The first Bragg reflective layer (610) of the present invention can reflect blue light scattered from a scatterer (431b) included in the color conversion layer (411, 421), and can reflect blue light emitted from a light source that is not absorbed and passes through the color conversion layer (411, 421). Additionally, the second Bragg reflective layer (620) transmits blue light emitted from a light source and can re-reflect blue light emitted from quantum dots (411a, 421a) included in the color conversion layer (411, 421, 431) and / or blue light scattered from a scatterer (431b), and can also re-reflect blue light reflected from the first Bragg reflective layer (610) back to the color conversion layer (411, 421).

[0096] The first Bragg reflective layer (610) of the present invention can transmit red light and / or green light emitted from quantum dots (411a, 421a) included in the color conversion layer (411, 421) and red light and / or green light scattered from a scatterer (431b). The second Bragg reflective layer (620) can reflect red light and / or green light emitted from quantum dots (411a, 421a) included in the color conversion layer and red light and / or green light scattered from a scatterer (431b). Additionally, the red light and / or green light reflected from the first Bragg reflective layer (610) can be reflected back to the color conversion layer (411, 421, 431).

[0097] Therefore, since the blue light emitted from the first Bragg reflective layer (610) and the second Bragg reflective layer (620) can be recycled for quantum dot emission, the light conversion efficiency of the red light-emitting quantum dots (411a) and green light-emitting quantum dots (421a) within the color conversion layer can be improved.

[0098] On the other hand, when the center wavelengths of the first Bragg reflective layer (610) and the second Bragg reflective layer (620) are significantly separated from each other, the optical interference consistency is broken when they are stacked within the same display device as shown in FIG. 5. In this case, the reflection efficiency in a specific wavelength band is reduced, or unintended light transmission or reflection occurs in adjacent wavelength regions, thereby reducing the consistency of the overall optical performance.

[0099] To this end, it is desirable to maintain the center of the reflection wavelength FWHM of the second Bragg reflection layer (620) within ±5 nm relative to the center of the FWHM of the first Bragg reflection layer (610). This ensures center wavelength matching between reflection bands and enables stable and uniform reflection characteristics in the target design wavelength region.

[0100] Color conversion layer

[0101] The color conversion layer (411, 421, 431) of the present invention is disposed within a subpixel area on a substrate and may include quantum dots (411a, 421a) and scatterers (431b) as shown in FIG. 1 and FIG. 5.

[0102] The above quantum dots (411a, 421a) can be appropriately manufactured by controlling the size of the quantum dots (411a, 421a) or controlling the elemental ratio within the quantum dots (411a, 421a). The above quantum dots (411a, 421a) refer to crystals of semiconductor compounds, and a light-emitting device emitting light of various wavelengths can be realized by using quantum dots (411a, 421a) of different sizes or by using quantum dots (411a, 421a) with different elemental ratios within them. Specifically, the quantum dots (411a, 421a) can be implemented to emit red, green, or blue light. The core material of the quantum dots emitting red light, green light, and blue light may be one of InP, InGaP, InZnP, and InNaP, which are mixture compositions based on InP. In addition, one or more of CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, SnS, SnSe, SnTe, PbS, PbSe, PbTe, SiC, SiGe, CuInSe2, CuInS2, CuInGaSe, CuInGaS, AgInS, AgInGaS, and perovskite may be included.

[0103] In the case of a quantum dot having a single shell layer on the core of the above quantum dot, the shell material may be one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnSeS, ZnTeS, HgS, HgSe, HgTe, InS, InZnS, PbS, and SrSe. Additionally, in the case of a quantum dot having multiple shell layers on the core of the above quantum dot, the shell material of each layer may be one or more of the shell materials that the single shell layer may have. Specifically, the first shell material closest to the core may be ZnSe, and the second shell material closest may be ZnS. A mixed composition such as ZnSeS may also be used as the first and second shell materials.

[0104] The color conversion layer (411) of the first subpixel area (410) of the present invention may include a quantum dot (411a) that emits red light, and the color conversion layer (421) of the second subpixel area (420) may include a quantum dot (421a) that emits green light. Additionally, as an example of the present invention, the color conversion layer (431) of the third subpixel area (430) may include a quantum dot that emits blue light when the light source has a wavelength of 360 nm to 410 nm, and may not include a quantum dot that emits blue light when the light source has a wavelength of 440 nm to 470 nm.

[0105] The color conversion layer (411, 421, 431) of the present invention may further include a scatterer (431b). The scatterer (431b) is intended to scatter light non-directionally and may be an inorganic particle, specifically, at least one of TiO2, ZnO, Al2O3, SiO2, and hollow silica. Additionally, the scatterer (431b) may be an organic particle, and the organic particle may be an acrylic resin or a urethane resin. The diameter of the scatterer (431b) may be 50 nm to 10 μm.

[0106] In the present invention, a color conversion layer (411 or 421 or 431) can be formed through an ink comprising the quantum dots (411a or 421a) and scatterers (431b), and the color conversion layer can be formed by any one of inkjet printing, screen printing, and fluid self-assembly printing. Specifically, an inkjet printing process can be used.

[0107] In the present invention, the ink for forming a color conversion layer (411) in a first subpixel area (410) may include quantum dots (411a) that emit red light and may further include scatterers (431b). The ink may include quantum dots (411a) and scatterers (431b) together with a solvent and may further include an additive for maintaining the quality of the ink.

[0108] Specifically, the ink for forming a color conversion layer (411) in a first subpixel area (410) in the present invention comprises a quantum dot (411a) that emits red light and a scatterer (431b), and may include dipropylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol methyl ether acetate, cyclododecene, or a combination thereof to ensure viscosity, uniformity, and surface tension characteristics of the ink. The quantum dot (411a) that emits red light may be included at a concentration of 1% to 30% by weight based on the total weight of the ink, and the scatterer (431b) may be included at a concentration of 0.1% to 1% by weight based on the total weight of the printing ink.

[0109] In the present invention, the solvent included in the ink for forming a color conversion layer (411) in the first subpixel area (410) may include a hydrophobic solvent to evenly disperse the quantum dots (411a) and scatterers (431b) whose surfaces are coated with organic functional groups. Specifically, it may include dipropylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol methyl ether acetate, cyclododecene, or a combination thereof, and may be a combination of cycloalkane compounds having a straight-chain alkyl group having 4 to 16 carbon atoms, such as isobornyl acrylate, dipentaerythritol hexaacrylate, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane, which can improve quantum dot dispersion stability, and aromatic hydrocarbon compounds having a straight-chain alkyl group having 2 to 12 carbon atoms, such as ethylbenzene, propylbenzene, butylbenzene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, cyclohexylbenzene, tetral, decalin, mesitylene, toluene, and xylene, which improve the chargeability of the ink. In addition, the dispersion may contain two or more solvents with different boiling points and surface tensions to control the coffee ring phenomenon caused by the Marangoni effect. Preferably, it may contain a combination of a solvent with a high boiling point and low surface tension and a solvent with a low boiling point and high surface tension. For example, it may contain a combination of cyclone hexylbenzene (boiling point: 240°C, surface tension: 36 mN / m) and decane (boiling point: 174°C, surface tension: 24 mN / m) solvents. The solvent may be included at a concentration of 40% to 70% by weight based on the total weight of the ink.

[0110] In the present invention, the ink may further include surfactants, viscosity modifiers, dispersants, and drying modifiers as additives. For example, Triton X-100 or a polyoxyethylene-based surfactant may be included as a surfactant that controls the surface tension of the ink, and polymer additives and glycol-based compounds may be included as viscosity modifiers that affect the spray stability at the printer head. Polyvinylrolidone or polyethylene glycol may be included as a dispersant that ensures the quantum dots and scatterers are uniformly dispersed within the dispersion and prevents precipitation. Glycol ether or dipropylene glycol may be included as a drying modifier and a curing agent. The additives may be included at a concentration of 20% by weight or less based on the total weight of the ink.

[0111] In the present invention, the ink for forming a color conversion layer (421) in the second subpixel area (420) contains the same components and concentrations as the ink for forming a color conversion layer (411) in the first subpixel area (410), except that it contains quantum dots (421a) that emit green light instead of quantum dots (411a) that emit red light. Since the detailed description thereof is the same as described above, it will be omitted.

[0112] In the present invention, the ink for forming a color conversion layer (431) in the third subpixel area (430) has the same components and concentration as the ink for forming a color conversion layer (411) in the first subpixel area (410), except that it does not contain quantum dots (411a) that emit red light. A detailed description thereof is omitted as it is the same as described above.

[0113] The thickness of the color conversion layer (411, 421, 431) of the present invention may be 0.1 μm to 10 μm, and specifically, 2 μm to 10 μm. The color filter (100) of the present invention includes a Bragg reflective layer (610, 620), thereby reducing the thickness of the color conversion layer (411, 421, 431) to 10 μm or less, and thus providing a low-cost display device.

[0114] Method for manufacturing color filters

[0115] The method for manufacturing a color filter (100) of the present invention may include the steps of: forming a first subpixel area (410), a second subpixel area (420), and a third subpixel area (430) by installing a partition (300) on a substrate (200); forming a first Bragg reflective layer (610) by applying a composition including micro Bragg reflector flakes to the first subpixel area (410) and the second subpixel area (420); and forming a color conversion layer (411, 421, 431) on the substrate (200) within the first Bragg reflective layer (610) and the third subpixel area (430).

[0116] First, the method for manufacturing a color filter according to the present invention includes the step of forming a first sub-pixel area (410), a second sub-pixel area (420), and a third sub-pixel area (430) by installing a partition (300) on the substrate (200). The partition (300) may be manufactured, for example, by an imprinting or photolithography process. Since the height and composition of the partition (300) are the same as those described in the description of the color filter, a detailed description is omitted.

[0117] Next, the method includes the step of forming a first Bragg reflective layer (610) by applying a composition containing micro Bragg reflector flakes to the first subpixel area (410) and the second subpixel area (420) by means of inkjet printing or the like. Since the step of forming the first Bragg reflective layer is identical to the detailed description of the components and manufacturing method of the method for manufacturing micro Bragg reflector flakes of the present invention, a detailed description is omitted.

[0118] Next, the method may include the step of forming a color conversion layer (411, 421, 431) on a substrate (200) within the upper part of the first Bragg reflection layer (610) and the third subpixel area (430). The color conversion layer (411, 421, 431) of the present invention may be formed through one of inkjet printing, screen printing, and fluid self-assembly printing. Since the constituent components of the color conversion layer (411, 421, 431) are the same as those described in the description of the color conversion layer, a detailed description is omitted.

[0119] Additionally, the manufacturing method of the present invention may further include the step of forming a second Bragg reflective layer (620) on the color conversion layer. The step of forming the second Bragg reflective layer (620) is identical to the detailed description of the components and manufacturing method of the manufacturing method of the micro Bragg reflector flake of the present invention, except that the number of stacking layers of the high refractive index layer (631) and the low refractive index layer (632) and the thickness of each of the high refractive index layer (631) and the low refractive index layer (632) can be adjusted so that the interference reflectance of the second Bragg reflective layer is in the range of 0% to 50%. Therefore, a detailed description is omitted.

[0120]

[0121] The present application will be explained in more detail below through embodiments according to the present application, but the scope of the present application is not limited by the embodiments presented below.

[0122]

[0123] <Example>

[0124] Reflectance calculation based on the number of refractive index layer stacks

[0125] The reflectance according to the number of layers of the refractive index layer was calculated using the Essential Macleod (Thin Film Center Inc, Core) simulator.

[0126] As one example, Si3N4 with a refractive index of 2.02 was set as the high-refractive-index layer material and SiO2 with a refractive index of 1.46 was set as the low-refractive-index layer material, and the thicknesses of each layer were set to 27 nm and 111 nm, respectively. Subsequently, when Si3N4 and SiO2 were alternately stacked, the reflectance of light (%) according to the total number of stacked layers was simulated, and the results are shown in Fig. 6. As shown in Fig. 6, it was confirmed that the reflectance of light gradually increased as the total number of stacked layers increased to 14, 20, 30, and 40.

[0127] As another example, Si3N4 with a refractive index of 2.02 was set as the high-refractive-index layer material and SiO2 with a refractive index of 1.46 was set as the low-refractive-index layer material, and the thicknesses of each layer were set to 13 nm and 138 nm, respectively. Subsequently, the simulation result (dotted line) for the light reflectance (%) of a microbragg reflector formed by alternately stacking Si3N4 and SiO2 5 times to form a total 10-layer structure was compared with the simulation result (solid line) for the light reflectance (%) of a microbragg reflector formed by alternately stacking a total of 14 layers by setting Si3N4 with a refractive index of 2.02 as the high-refractive-index layer material and SiO2 with a refractive index of 1.46 as the low-refractive-index layer material, respectively, and setting the thicknesses of each layer to 27 nm and 111 nm, respectively, and is shown in FIG. 7 (a).

[0128] As another example, Si3N4 with a refractive index of 2.02 was set as the high-refractive-index layer material and SiO2 with a refractive index of 1.46 was set as the low-refractive-index layer material, and the thickness of each layer was set to 27 nm and 111 nm, respectively. Subsequently, the simulation results (dotted line) for the light reflectance (%) of a microbragg mirror formed by alternately stacking Si3N4 and SiO2 three times to form a total 6-layer structure were shown in FIG. 7 (b), along with the simulation results (solid line) for the light reflectance (%) of a microbragg mirror formed by alternately stacking Si3N4 and SiO2 seven times to form a total 14-layer structure under the same material and thickness conditions.

[0129] As shown in Figures 7 (a) and (b), it was confirmed that the maximum reflectance was approximately 40% in both low reflectance (dotted line) characteristics. However, as shown in Figure 7 (b), in a microbragg reflector with a maximum reflectance of 50% or less, even if the material and thickness of each layer are the same, when the number of stacking layers of the high refractive index layer and the low refractive index layer is small, a phenomenon was observed in which the center wavelength of the full width at half maximum (FWHM) of the reflection band shifts from approximately 440 nm to approximately 400 nm.

[0130] That is, from the result in Fig. 7(a), it was confirmed that even when using the same high-refractive-index and low-refractive-index layer materials, the center wavelength of the FWHM of the reflection band of the two micro Bragg mirrors being compared remained close to each other as the thickness and number of layers of each layer were appropriately set. On the other hand, from Fig. 7(b), it was confirmed that even under the same material and thickness conditions, the center wavelength of the FWHM of the reflection band between the two samples was separated from each other due to the difference in the number of layers.

[0131] Through this, it was confirmed that in order to ensure consistency in reflection characteristics between micro Bragg reflectors under the same material conditions, it is necessary to design by appropriately adjusting the thickness and number of layers of each layer. In addition, it was found that it is desirable to design the second Bragg reflective layer according to the above embodiment so that the center of the FWHM of the reflection wavelength is maintained within ±5 nm relative to the center of the FWHM of the first Bragg reflective layer.

[0132] Micro Bragg reflector flake manufacturing

[0133] To manufacture micro Bragg reflector flakes, a separation film was formed by depositing an Al thin film with a thickness of 500 nm on a silicon substrate using an electron beam evaporator (E-beam evaporator).

[0134] Next, to form a Bragg reflection layer on the above Al separation film, a Si3N4 thin film with a thickness of 27 nm was formed by supplying 5% SiH4 / N2400 sccm, NH325 sccm, and N2500 sccm using a plasma chemical vapor deposition method under conditions of plasma power 200 W, process pressure 1000 mTorr, and process temperature 350℃.

[0135] Afterwards, a SiO2 thin film was continuously formed while maintaining a vacuum. At this time, a SiO2 thin film with a thickness of 111 nm was formed by supplying 5% SiH4 / N2 150 sccm and N2O 700 sccm under conditions of plasma power 40 W, process pressure 1000 mTorr and process temperature 350℃.

[0136] Based on the results of reflectance calculations according to the number of refractive index layer stacking performed in the above example, a Bragg mirror with a thickness of 966 nm was manufactured by alternately stacking Si3N4 and SiO2 seven times each to form a total of 14 layers.

[0137] Next, a photolithography process was performed to form micro Bragg reflector flakes. A photosensitive material for photolithography (Dongjin, DPR-i2402) was applied onto the Bragg reflector, and spin coating was performed at 3,000 rpm for 30 seconds. Subsequently, the photosensitive material was cured on a hot plate at 90°C for 1 minute to form a photosensitive film with a thickness of 8 μm. Afterward, a mask capable of forming an island pattern of 10 μm x 10 μm was aligned onto the photosensitive material, and then UV light at 750 mJ / cm² 2 After investigating, the island pattern for masking the micro Bragg reflector was formed by developing and washing-drying.

[0138] Next, after loading the substrate with the masking island pattern formed thereon into the chamber of the dry etching equipment, the vacuum level inside the chamber is set to 10 -6 Under conditions of Torr, plasma power 200 W, process pressure 50 mTorr, and CF4 flow rate 50 sccm, the Bragg mirror was etched until the Al thin film was exposed in an area excluding the island pattern for masking the Bragg mirror.

[0139] After the etching process was completed, the sample was removed from the chamber and immersed in a photosensitive material stripper (Merck, AZ 100 remover) at 40°C to remove the photosensitive material, then washed with deionized water, and dried in a vacuum oven at 90°C for 10 minutes to produce a microbragg mirror as shown in FIGS. 8 (a), (b), (c), and (d). FIGS. 8 (a) and (b) are top views of the microbragg mirror, and FIGS. 8 (c) and (d) are side views of the microbragg mirror.

[0140] Next, the Al thin film located at the bottom of the microbragg reflector formed on the silicon substrate was removed using an etching solution (Merck, Aluminum Etchant Type A) at 25°C, thereby separating the microbragg reflector flakes from the silicon substrate. Subsequently, 20 ml of the etching solution in which the microbragg reflector flakes were dispersed was obtained using a pipette.

[0141] Next, 20 ml of the etching solution (hereinafter referred to as the microbragg reflector flake solution) containing the obtained microbragg reflector flakes was dispersed in 100 ml of deionized water to prepare a microbragg reflector flake dispersion, and then centrifuged to prepare a microbragg reflector flake ink.

[0142] Specifically, 50 ml of the above-mentioned microbragg reflector flake dispersion was injected into a tube, and the microbragg reflector flakes settled at the bottom of the tube were separated from the supernatant by centrifugation at 500 rpm for 1 minute. Subsequently, 20 ml of anhydrous ethanol (Sigma-Aldrich, Ethyl alcohol, Pure) was added to the tube containing the settled microbragg reflector flakes, and the microbragg reflector flakes were dispersed in the anhydrous ethanol by performing ultrasonic treatment for 10 minutes using a sonication device (ELMASONIC_P_60H, 37 kHz). Afterward, the centrifugation process was repeated three times under the same conditions, and a microbragg reflector flake ink dispersed in 20 ml of anhydrous ethanol was produced as shown in FIG. 9 (a) and (b).

[0143] Figures 9(a) and 9(b) show a photograph of microbragg reflector flakes dispersed in 20 ml of anhydrous ethanol contained in a 50 ml conical tube, and a photograph of the same taken with an optical microscope. The microbragg reflector flakes are formed by alternately stacking SiO2 with a thickness of 111 nm as a low-refractive-index layer and Si3N4 with a thickness of 27 nm as a high-refractive-index layer seven times, and have dimensions of 10 μm in width, 10 μm in length, and 0.966 μm in height. The microbragg reflector flakes are dispersed at a concentration of 0.01 wt% based on the total weight of 20 ml of anhydrous ethanol.

[0144] Manufacturing of ink for forming a color conversion layer

[0145] To prepare an ink for forming a color conversion layer, 10 g of quantum dots and 25 ml of a dispersant (BYK, model BYK-102) were mixed, and then 100 ml of propylene glycol monomethyl ether acetate (PGMEA) was added and mixed. Subsequently, a quantum dot dispersion was prepared by centrifuging at 500 rpm for 5 hours. The quantum dots have a structure comprising an InP core with a diameter of 2 nm, a ZnSe shell with a thickness of 3 nm as the first shell closest to the core, and a ZnS shell with a thickness of 1 nm as the second shell located outside of it, and are quantum dots with a total diameter of 6 nm that emit green light.

[0146] Next, 200 ml of deionized water was added to the above quantum dot dispersion, and a centrifugation process was performed to precipitate the quantum dots, and then the precipitated quantum dots were obtained.

[0147] Next, 0.2 g of TiO2 having an average particle size of 200 nm, 15 g of isobornyl acrylate, and 5 g of dipentaerythritol hexaacrylate were added as light scatterers to the obtained quantum dots and mixed, and then 3 g of an initiator (Kwangshin Young Radchem, Model OXE-02) was dissolved to prepare an ink for forming a color conversion layer.

[0148] Color filter manufacturing

[0149] To evaluate the emission spectrum characteristics of a color filter including a micro Bragg reflector, a color filter was manufactured as follows.

[0150] First, as in the manufacturing of the micro Bragg reflector flakes above, a barrier was formed to form a color conversion layer on a Bragg reflector with a thickness of 966 nm, consisting of a total of 14 layers by alternately stacking Si3N4 and SiO2 7 times each.

[0151] Specifically, photolithography was performed to manufacture barriers to partition subpixel regions on a Bragg mirror with a thickness of 966 nm, which consists of a total of 14 layers formed by alternately stacking Si3N4 and SiO2 prepared in the above example 7 times each. After spin-coating a photoresist for manufacturing barriers (Microchem, Model SU-8 2020) onto the surface of the Bragg mirror at 500 rpm for 5 seconds and at 4000 rpm for 30 seconds, 150 mJ / cm² 2 By exposing with energy, a barrier with a thickness (in the direction parallel to the surface of the Bragg mirror) of 10 μm and a height (in the direction perpendicular to the surface of the Bragg mirror) of 15 μm was formed on a substrate.

[0152] Next, after performing Ar plasma treatment on the surface of the above partition and Bragg reflector for 1 minute, an electrohydrodynamic printing process was performed on ink for manufacturing a color conversion layer containing the green light-emitting quantum dots prepared in the above example within each subpixel area partitioned by the above partition, under conditions of a nozzle inner diameter of 10 μm and a distance between the substrate and the nozzle of 100 μm. Subsequently, 100 mJ of ultraviolet light (λ= 360 nm) was irradiated to form a color conversion layer with a width of 10 μm and a thickness of 5 μm. Then, a color filter was manufactured by curing the color conversion layer through heat treatment at 150°C for 30 minutes.

[0153]

[0154] <Comparative Example>

[0155] A color filter having a color conversion layer containing quantum dots that emit green light was manufactured by performing the same method as in the above example, except that it does not have a micro Bragg reflector.

[0156]

[0157] <Evaluation Results>

[0158] To verify the effect of the presence or absence of a micro Bragg reflector, the emission spectrum was measured for each color filter manufactured in the above examples and comparative examples. A blue light source emitting a center wavelength of 450 nm at a driving condition of 1 mA was driven using an EL emission measurement device, and luminance values ​​were measured in the wavelength range of 360 nm to 780 nm using a CCD spectrometer.

[0159] Figure 10 shows the results of comparing the emission spectra of a color filter (example, with DBR) prepared according to an embodiment of the present invention, which includes a color conversion layer containing 5 μm thick quantum dots emitting green light and a microbragg reflector, and a color filter prepared according to a comparative example of the present invention, which includes a color conversion layer containing 5 μm thick quantum dots emitting green light but does not include a microbragg reflector (comparative example, wo DBR).

[0160] As shown in FIG. 10, in a color filter containing a microbragg reflector manufactured according to an embodiment of the present invention (example, with DBR), the detection of blue light was significantly suppressed, whereas in a color filter not containing a microbragg reflector (comparative example, with DBR), the luminance value of blue light was measured to be 17,500 au or higher.

[0161]

[0162] [Explanation of the symbol]

[0163] 100: Color filter

[0164] 200: Substrate

[0165] 300: Bulkhead

[0166] 400: Pixel area

[0167] 410: 1st subpixel area

[0168] 411: Color conversion layer of the first subpixel area

[0169] 411a: A quantum dot emitting red light included in the color conversion layer of the first subpixel area

[0170] 420: Second subpixel area

[0171] 421: Color conversion layer of the second subpixel area

[0172] 421a: A quantum dot emitting green light included in the color conversion layer of the second subpixel area

[0173] 430: 3rd subpixel area

[0174] 431: Color conversion layer of the third subpixel area

[0175] 431b: Spawner

[0176] 610: First Bragg reflection layer

[0177] 620: Second Bragg reflector

[0178] 631: High refractive index layer

[0179] 632: Low refractive index layer

[0180] 633: Bragg layer

Claims

1. A substrate; and a color filter comprising a plurality of pixel regions disposed on the substrate, Each of the above pixel regions includes a first sub-pixel region, a second sub-pixel region, a third sub-pixel region, and a partition disposed on the substrate and surrounding each of the sub-pixel regions, and Each of the above subpixel regions includes a color conversion layer disposed on the substrate, and A color filter comprising a first subpixel region and a second subpixel region, wherein the first subpixel region and the second subpixel region include a first Bragg reflection layer between a substrate and a color conversion layer.

2. In Paragraph 1, A color filter further comprising a second Bragg reflection layer on top of the color conversion layer of each of the above subpixel regions.

3. In Paragraph 1, A color filter having a color conversion layer thickness of 0.1 μm to 10 μm.

4. In Paragraph 1, The color conversion layer of the first subpixel region includes quantum dots that emit red light, and The color conversion layer of the second subpixel region above is a color filter comprising quantum dots that emit green light.

5. In Paragraph 1, A color filter in which the interference reflectance of the first Bragg reflective layer is 50% to 100%.

6. In Paragraph 2, A color filter in which the interference reflectance of the second Bragg reflective layer is 0% to 50%.

7. In Paragraph 1, A color filter in which the first Bragg reflective layer and the second Bragg reflective layer are formed by alternately stacking a high refractive index layer and a low refractive index layer.

8. In Paragraph 7, The high refractive index layer has a refractive index of 1.5 to 4.0, and The above low-refractive-index layer has a refractive index of 1.1 to 3.0, and The above high-refractive-index layer is a color filter having a refractive index that is 0.1 or higher than that of the above low-refractive-index layer.

9. In Paragraph 7, A color filter in which the first Bragg reflective layer and the second Bragg reflective layer each have a total number of layers of high refractive index and low refractive index layers of 4 to 40.

10. In Paragraph 1 or 2, A color filter comprising a first Bragg reflective layer and a second Bragg reflective layer, wherein the first Bragg reflective layer and the second Bragg reflective layer comprise micro Bragg reflector flakes.

11. A display device comprising the color filter of claim 1.

12. A step of forming a separation layer on a substrate; A step of forming a Bragg reflector on the separation layer; A step of forming a micro Bragg reflector by etching the above Bragg reflector in a direction perpendicular to the substrate; and A method for manufacturing microbragg reflector flakes comprising the step of separating the microbragg reflector to form flakes.

13. Contains microbragg reflector flakes and a solvent, A printing composition in which the above-mentioned microbragg reflector flakes have a width of 50 μm or less, a length of 50 μm or less, and a height of 5 μm or less.

14. A substrate; and a plurality of pixel regions disposed on the substrate, a method for manufacturing a color filter, comprising: a substrate; and a plurality of pixel regions disposed on the substrate. A step of forming a first sub-pixel region, a second sub-pixel region, and a third sub-pixel region by installing a partition on the substrate; A step of forming a first Bragg reflective layer by applying a composition comprising micro Bragg reflector flakes to the first subpixel area and the second subpixel area; and A step of forming a color conversion layer on the substrate within the first Bragg reflective layer and the third subpixel area; A method for manufacturing a color filter including 15. In Paragraph 14, A method for manufacturing a color filter, further comprising the step of forming a second Bragg reflection layer on the color conversion layer.

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