KR20220064078A - Structural Color Structure And Manufacturing Methods Thereof - Google Patents

Abstract

The present invention relates to a structural color structure. The present invention provides a structural color structure. Provided is a structural color structure including a plurality of structural color elements arranged on a substrate at a predetermined pitch, wherein the plurality of structural color elements include one end and the other end contacting a substrate, and a part of the plurality of structural color elements is a first structural color element including a direction changing part which extends upward from the contact point with the substrate and bends to a direction in parallel with the substrate. According to the present invention, a structural color structure with high resolution can be implemented.

Description

Structural Color Structure And Manufacturing Methods Thereof

The present invention relates to a nano-structured color structure and a method for manufacturing the same, and more particularly, to a color structure manufactured by 3D printing and a method for manufacturing the same.

Structural color refers to a reflection color that appears when only light of a specific wavelength is diffracted by a nanostructure that is regularly repeated at the wavelength level of light. In nature, various structural colors due to nanostructures are observed in insect carapaces, bird feathers, and human eyes, but it is not easy to artificially implement them. On the other hand, the structure color does not consume energy to drive, and the color changes sensitively to the displacement of the structure, so that it can be used for a sign board, a display, a sensor, etc., and active research is being conducted on this.

Conventionally, various methods have been tried to implement the structural color. For example, a method of arranging nanoparticles of a certain size with the aid of surface tension of a liquid (Langmuir-Blodgett et al.), a method of etching a flat surface into a nanostructure by a semiconductor exposure process, and a method of localizing light in a liquid phase of a photocurable polymer and a method of curing it into a nanostructure by irradiating it.

However, it is known that it is difficult to implement the structural color at a desired point in the conventional structural color implementation method as described above, and it is very difficult to implement on the surface of various materials because it is limited to a specific material. Accordingly, there is a disadvantage in that it is difficult to apply it to high-tech products such as electronic devices, optical devices, and displays. In addition, the above-described prior art has limitations in color control because it uses predetermined nanoparticles, and requires very expensive equipment and materials for implementation.

(1) “Structural color three-dimensional printing by shrinking photonic crystals”, Nature communications (2019)10:4340 (https://doi.org/10.1038/s41467-019-12360-w) (2) “Large-Scale Noniridescent Structural Color Printing Enabled by Infiltration-Driven Nonequilibrium Colloidal Assembly”, Advanced Materials 2018, 1705667 (3) “Structural color using organized microfibrillation in glassy polymer films”, NATURE VOL 570 p363 (2019) (4) “Scalable Inkjet-Based Structural Color Printing by Molding Transparent Gratings on Multilayer Nanostructured Surfaces”, ACS Nano 2018, 12, p3112-3125

Another object of the present invention is to provide a method for realizing a structural color by a meniscus-guided printing technique.

Another object of the present invention is to provide a method for implementing a high-resolution structural color structure by using the surface tension of the meniscus.

Another object of the present invention is to provide a technique capable of directly printing a nanostructure expressing a structural color or a structure thereof at a desired location on a desired surface of a material.

An object of the present invention is to provide a method for implementing a three-dimensional nano-structured color structure by applying a three-dimensional printing technique.

In addition, an object of the present invention is to provide a structure color structure implemented by the above-described method and various articles based on the structure.

In order to achieve the above technical object, the present invention provides a structure color structure including a plurality of color structure elements arranged at a predetermined pitch on a substrate, wherein the plurality of color structure elements includes one end and the other end in contact with the substrate and that some of the plurality of structural color elements is a first structural color element including a turning portion extending upward from a point of contact with the substrate at one end and then bent in a direction parallel to the substrate Provides a structure color structure characterized by.

In the present invention, it is preferable that the first structural color element is manufactured while forming a gap between the direction changing part and the substrate.

In the present invention, the pitch of the first structural color element is 500 to 2,000 nm, 500 to 1,500 nm, 500 to 1,000 nm, 500 to 900 nm, 600 to 2,000 nm, 600 to 1,500 nm, 600 to 1,000 nm, 600 to 900 nm, 700-2,000 nm, 700-1,500 nm, 700-1,000 nm, 800-2,000 nm, 800-1,500 nm, or 800-1,000 nm is preferable.

The maximum gap at the turning part is 200 nm to 2,000 nm. 300-2,000 nm, 400-2,000 nm, 500-2,000 nm, 6,00-2000 nm, 7,00-2000 nm, 200-1,000 nm, 300-1,000 nm, 400-1,000 nm, 500-1,000 nm, 600 -1,000 nm, 700-1,000 nm, 200-900 nm, 300-900 nm, or 400-900 nm is preferable.

The structural color structure of the present invention may further include a connecting element connecting the structural color elements at the end of the first structural color element.

In order to achieve the above other technical object, the present invention provides a method for manufacturing a structural color structure by printing structural color elements at predetermined intervals, wherein the printing of the structural color elements comprises: (a) dielectric properties for printing the structural color elements providing an ink comprising a material and a solvent for dissolving or dispersing the dielectric material; (b) contacting a nozzle containing the ink to a first location on the substrate; (c) discharging ink while moving the nozzle relative to the substrate by a predetermined distance upward and then moving the nozzle in a parallel direction with respect to the substrate; and (d) contacting the nozzle to the substrate.

The present invention may further comprise the step of printing a connecting element connecting the structural color element.

In the present invention, the ink may exhibit Newtonian behavior.

In the present invention, it is preferable that the ink discharged from the nozzle in step (c) forms a meniscus between the substrate and the ink, and the ink is continuously discharged from the nozzle by the surface tension of the meniscus. . In addition, at this time, it is preferable that the ink of the meniscus formed between the nozzle and the substrate evaporates spontaneously.

According to the present invention, it is possible to implement a structure color structure at a desired position on a substrate of any material by applying a meniscus guided printing technique.

In addition, according to the present invention, a high-resolution structural color structure can be realized by discharging the printing ink formed at the tip of the nozzle by using the surface tension of the meniscus.

The structural color structure of the present invention enables various articles such as signboards, sensors, and displays to be implemented.

1 is a diagram conceptually illustrating an operation process of a printing pen 110 for printing a structure according to an embodiment of the present invention.
2 is a diagram schematically illustrating a process of forming a structural color element according to an embodiment of the present invention.
3 is a diagram sequentially illustrating an example of a procedure for forming a color structure structure according to an embodiment of the present invention.
4 is an electron microscope photograph of a structure color structure pattern prepared according to an embodiment of the present invention.
5 is an electron microscope photograph of a structural color structure pattern prepared according to Comparative Example, which is another embodiment of the present invention.
6 is a photograph showing a diffraction test result according to an observation position for a sample prepared according to an embodiment of the present invention.
7 is a photograph showing the results of a diffraction experiment of a structural color structure having different pitches of structural color elements according to another embodiment of the present invention.
8 is an example of implementing text and images according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention.

1 (a) to (c) are diagrams conceptually illustrating an operation process of the printing pen 110 for printing a structure according to an embodiment of the present invention.

1A illustrates an initial state in which the tip of the nozzle of the pen 110 comes into contact with the substrate 10 and the nozzle. Ink is stored inside the pen 110 . The ink includes a solvent 34 in which the structure-forming material 32 is dissolved or dispersed. In addition, the ink may further include a dispersant or a binder.

In the present invention, the structure-forming material 32 preferably includes a dielectric material. For example, a polymer material such as polystyrene, poly methyl methacrylate (PMMA), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), or polycaprolactone (PCL), and an inorganic material such as silicon dioxide may be used. When the above-described polymer material is used as the structure-forming material, the concentration of the structure-forming material in the ink in the present invention may be appropriately selected within the range of 0.2 to 5.0 wt%.

In addition, as the structure-forming material in the present invention, an inorganic compound such as oxide, nitride, or carbide may be used.

In the present invention, the solvent includes at least one or more volatile substances such as xylene, toluene, chlorobenzene, acetone, and the like. Organic solvents may be used.

When the pen 110 moves upward by a predetermined interval from the state of FIG. 1A , a meniscus B of ink is formed between the nozzle and the substrate. In this state, when the pen 110 moves upward at a predetermined speed, ink is discharged from the nozzle. At this time, the meniscus B to which the surface tension of the ink in solution acts is formed on the nozzle side, and the structure A including the structure forming material is formed on the substrate side by evaporation of the solvent 24 . In the present invention, the solvent of the meniscus (B) has a high specific surface area and can be spontaneously evaporated even at room temperature. Of course, according to the present invention, it is not excluded that an appropriate heating means is added to the operation process of the pen. In the present invention, the formation of the meniscus and evaporation of the solvent occur almost simultaneously, leaving the structure-forming material in a very short time. The structure-forming material may support itself as a solidified polymer.

In the present invention, the width of the meniscus is maintained within an appropriate range to provide a high specific surface area for evaporation of the solvent. In the present invention, the width of the meniscus depends on the aperture of the nozzle and the moving speed of the nozzle. Also, since the ink particles flow in the conduit of the meniscus, the line width of the resulting pattern has a value equal to or smaller than the width d of the meniscus.

Referring back to FIG. 1 , at a predetermined moving speed v, the meniscus has a predetermined width d. However, as the moving speed increases, the width of the meniscus has a smaller value.

In one embodiment of the present invention, it is necessary to control the flow characteristics of the ink for seamless printing of the structure pattern. At this time, in the present invention, the flow characteristics of the ink can be controlled by adjusting the content of the structure-forming material or the additional binder or dispersant. In the present invention, the ink may exhibit Newtonian behavior. Alternatively, it is of course possible to control the flow characteristics of the ink by changing the concentration of the structure-forming material or introducing an additional rheological modifier.

Although FIG. 1C shows the process of ejection of ink, spontaneous evaporation, and pattern generation according to the movement of the pen upwards on the substrate 10 , the pen in a direction parallel to the substrate 10 is The processes of ejection of ink, spontaneous evaporation, and pattern generation even when moving can be described in the same manner.

2 is a diagram schematically illustrating a process of forming a structural color element according to an embodiment of the present invention.

First, a nozzle containing ink is moved to a predetermined position on a substrate, and then the nozzle is brought into contact with the substrate surface as shown in FIG. 2 ( 1 ). Materials that can be used as the substrate in the present invention are not particularly limited. As the substrate, an inorganic substrate such as quartz, silicon, or glass, or a polymer resin substrate such as PET may be used. The substrate material may be selected according to the intended use. For example, a substrate made of a transparent material may be used to implement a transparent display device.

Next, as shown in FIG. 2 (2), the nozzle is pulled upward a predetermined distance from the substrate surface is performed. At this time, the ink is discharged from the nozzle, and the discharged ink forms a meniscus in which surface tension by the ink in solution acts on the nozzle side, and the structure forming material is formed by evaporation of the solvent 24 on the substrate side. leave it At this time, the pulling distance is not particularly limited, but is preferably 1-3 μm. If the upward movement distance is too short, the meniscus is not completely separated from the substrate, making it difficult to implement a nano-sized pattern. If the upward movement distance is too long, it is difficult to produce a parallel pattern in the subsequent parallel movement step. In the drawings of FIG. 2, arrows indicate the relative movement direction of the nozzle with respect to the substrate. Here, a case in which the nozzle is moved is described, but otherwise, the substrate or the stage supporting the substrate may move in the opposite direction with respect to the nozzle. Of course.

Next, as shown in (3) of FIG. 2, the nozzle is moved in a direction substantially parallel to the substrate to a desired position on the substrate. In this process, the meniscus of the ink is maintained, the ink is continuously released, and the solvent is evaporated and the structure pattern is formed.

Then, as shown in FIG. 2 ( 4 ), the printing of the structural color element is completed by moving the nozzle downward at a predetermined position on the substrate.

As described with reference to FIG. 2 , in the present invention, the structural color element is a three-dimensional printed structure. In the present invention, a direction change portion is formed at one end (start end) of the structural color element by moving upwards of the substrate and moving in a direction parallel to the substrate. As a result, there is a gap between the structural color element and the substrate under the turning portion. In the above-described embodiment, the gap with the substrate is gradually or sharply decreased to disappear at the other end (end) of the structural color element. In the present invention, the maximum gap in the turning part may vary depending on the size of the structural color element, but 3 It can be set within μm.

In the present invention, the structural color element means a unit element constituting the structural color structure. The structural color element described in FIG. 2 was described as a one-dimensional linear pattern having a starting end and an end. However, in the present invention, the structural color element may include various shapes.

In the present invention, the structural color elements may be repeated at predetermined intervals to form a structural color structure. In the present invention, the repetition may be periodic or aperiodic. For example, a diffraction grating pattern in which a plurality of lines are arranged at regular intervals is an example of a structural color structure. In the present invention, a plurality of structural color elements constituting the structural color structure may be separated from each other. Of course, in the present invention, a plurality of structural color elements constituting the structural color structure may be connected. In this case, connecting elements for connecting the structural color elements can be used.

3 is a diagram sequentially illustrating an example of a procedure for forming a structural color structure using the structural color element of FIG. 2 according to an embodiment of the present invention. The box at the top of each drawing is a view showing the view from the upper surface of the substrate in each step.

Referring to FIGS. 3 (1) to (4), the structural color element e1 is formed in the same manner as described in FIG. 2 . Then, the connecting element e2 is formed in a direction perpendicular to the structural color element e1 by sequentially performing the operations shown in (5) to (7) of FIG. 3 . In the drawing, an arrow in an oblique direction represents the nozzle movement in a direction perpendicular to the ground.

Then, the structural color element according to (8) to (10), the connecting element according to (11) to (13), the structural color element according to (14) to (16), the connection according to (17) and (18) The formation of elements is taking place.

In this way, by using the connecting element, the structural color element can be continuously and repeatedly arranged without being interrupted.

In the present invention, the pitch of the structural color element is 500 to 2,000 nm, 500 to 1,500 nm, 500 to 1,000 nm, 500 to 900 nm, 600 to 2,000 nm, 600 to 1,500 nm, 600 to 1,000 nm, 600 to 900 nm, 700 to 2,000 nm, 700 to 1,500 nm, 700 to 1,000 nm, 800 to 2,000 nm, 800 to 1,500 nm, or 800 to 1,000 nm is preferable. In addition, in the present invention, the maximum gap in the direction changing part is 200 nm to 2,000 nm. 300-2,000 nm, 400-2,000 nm, 500-2,000 nm, 600-2,000 nm, 7,00-2,000 nm, 200-1,000 nm, 300-1,000 nm, 400-1,000 nm, 500-1,000 nm, 600-1,000 nm, 700-1,000 nm, 200-900 nm, 300-900 nm, or 400-900 nm is preferable.

Hereinafter, preferred embodiments of the present invention will be described in detail.

<Production of Ink>

An ink was prepared by dissolving polystyrene powder having a concentration of 1.6 mg/ml using xylene as a solvent. The prepared ink was designed at a very low concentration for smooth spontaneous ejection, and exhibited Newtonian behavior when the viscosity of the solution was very low.

<Example 1: Preparation of structural color structure>

A glass micropipette having a nozzle tip aperture diameter of 600 nm was manufactured using a P-2000 nozzle puller from Sutter Instruments. An array of parallel structural color elements was fabricated on a quartz substrate using the micropipette as a nozzle. Specifically, after filling the micropipette with the ink prepared in Experimental Example 1, as described with reference to FIG. 3 , a structure pattern in which a structural color element having a structure of a direction change part and a connecting element are repeatedly arranged was formed.

4 is an electron microscope photograph of a structure color structure pattern prepared according to an embodiment of the present invention. In FIG. 4, (a) is a photograph of the entire structure pattern, (b) is an enlarged photograph of the direction turning part, and (c) is a side view showing the gap of the direction turning part.

Referring to FIG. 4 , structural color elements and connecting elements having a fine line width of less than 1 μm are arranged in a zigzag shape. In addition, a maximum gap (δ) of less than 1 μm between the substrate and the structural color element can be identified near the turning portion. It can be seen that the structural color element forms a maximum gap near the turning part, and then the gap decreases as it goes down toward the end part (end point), and it is in contact with the substrate at the end part (end point).

The line width of the structural color element of the prepared structure was 600 nm, and the pitch was 1500 nm.

<Comparative example>

A structure pattern is formed using the same ink as in Example 1, but by omitting the upward and downward movement at the starting and ending points of the structural color element, the nozzle is moved only in the horizontal direction of the substrate, and the direction changing part is not provided. A structure pattern was formed. At this time, the pitch of the structural color elements in each sample was different.

5 is an electron microscope photograph of a structure color structure pattern according to a comparative example. 5 (a) to (d) correspond to samples with pitches of 1 μm, 1.5 μm, 2.0 μm, and 2.5 μm, respectively.

From FIG. 5 , it can be confirmed that the structural color element of the structure is not identified in the samples with a pitch of 2.0 μm or less, and the structural color element is identified only in the 2.0 μm sample.

<Experimental Example 2>

The reflection color was observed while tilting the structural color structure sample prepared in Example 1 with respect to the light source. A sample, a light source, and a camera (observer) were arranged as shown in FIG. 6(a), and the sample was observed while changing θ and φ. Here, θ is the angle between the light source (Light) and the observer (Observation), and φ is the angle formed by the structural color elements of the structural color nanostructure in the vertical direction.

Figure 6 (b) is a photograph of observing the sample by the camera at the observer's position. Referring to FIG. 6B , diffracted light (reflected light) having different wavelengths from red to blue may be observed as the arrangement is changed. At this time, with respect to the light incident from the light source, the plurality of structural color elements of the structural color structure act like a diffraction grating, and the wavelength of the diffracted light follows Bragg's law. That is, the diffracted light appears with a wavelength much smaller than the pitch of the color structure structure according to the relative arrangement of the structure color structure with respect to the incident light.

<Example 2>

A structural color structure was prepared by printing a group of structural color elements having different pitches on a single substrate. The pitch of the printed structural color elements is shown in Fig. 7(a). As shown, the pitch (Λ) of the structural color element group was varied from 900 to 1900 nm. In addition, one structural color element group was formed by appropriately setting the number of structural color elements so that the total length was 20 μm.

The prepared structure color structure was observed under the conditions of θ=23° and φ=0° in the arrangement of FIG. 6 (a). Referring to (b) of FIG. 7 , since the pitches of the structural color element groups are different, it can be seen that diffracted light of different colors can be observed according to the pitch of each element group.

<Example 3>

8 (a) to (c) are photographs showing an example in which the R, G, and B characters are implemented as structural color elements of different pitches. 8 (a) is an electron micrograph, (b) is an optical micrograph from the front of the substrate, (c) is a diffraction light photograph, according to the pitch of the structural color elements in the light source arrangement determined in FIG. It can be seen that each different reflected light is obtained.

8 (d) to (i) are photographs showing the results of implementing the Mona Lisa image as a structural color element. (d) of FIG. 8 is a photograph of the original image, (e) is an electron microscope photograph of a substrate on which the image is implemented, and (f) and (i) are photographs showing that different diffracted light appears depending on the arrangement of the light source.

As mentioned above, although the present invention has been described above through the embodiments of the present invention, the above description is by way of illustration of the present invention, and the present invention is not limited thereto. Without departing from the scope of the appended claims and the scope of the present invention, it should be regarded as belonging to the scope of the present invention to the extent that various modifications can be made by any person skilled in the art to which the present invention pertains.

Claims (10)

A structural color structure comprising a plurality of structural color elements arranged at a predetermined pitch on a substrate,
The plurality of structural color elements include one end and the other end in contact with the substrate,
Some of the plurality of structural color elements,
A structural color structure, characterized in that it is a first structural color element including a turning portion extending upward from a point of contact with the substrate at one end and then bent in a direction parallel to the substrate. According to claim 1,
The structure color structure, characterized in that the first structure color element forms a gap between the direction turning portion and the substrate. According to claim 1,
The structure color structure, characterized in that the pitch of the first structure color element is 700 ~ 2,000 nm. According to claim 1,
The structure color structure, characterized in that the maximum gap in the direction changing part is 200 ~ 2,000 nm. According to claim 1,
Structure color structure, characterized in that it further comprises a connecting element for connecting between the structure color elements at the end of the first color structure element. A method for producing a structural color structure by printing structural color elements at predetermined intervals, the method comprising:
The printing of the structural color element is
(a) providing an ink comprising a dielectric material for printing a structural color element and a solvent dissolving or dispersing the dielectric material;
(b) contacting a nozzle containing the ink to a first location on the substrate;
(c) discharging ink while moving the nozzle relative to the substrate by a predetermined distance upward and then moving the nozzle in a parallel direction with respect to the substrate; and
(d) method for manufacturing a structure color structure comprising the step of contacting the nozzle to the substrate 7. The method of claim 6,
The method for manufacturing a structure color structure, characterized in that it further comprises the step of printing a connecting element connecting the structure color element. 7. The method of claim 6,
The method of manufacturing a structural color structure, characterized in that the ink exhibits Newtonian behavior. 7. The method of claim 6,
In the step (c), the ink discharged from the nozzle forms a meniscus between the substrate and the structure color structure, characterized in that the ink is continuously discharged from the nozzle by the surface tension of the meniscus. manufacturing method. 10. The method of claim 9,
A method of manufacturing a structure color structure, characterized in that the ink of the meniscus formed between the nozzle and the substrate evaporates.

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