KR101686753B1 - Inverse opal photonic structure, method of preparing the same and colorimetric sensors using the same - Google Patents
Inverse opal photonic structure, method of preparing the same and colorimetric sensors using the same Download PDFInfo
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- KR101686753B1 KR101686753B1 KR1020150158796A KR20150158796A KR101686753B1 KR 101686753 B1 KR101686753 B1 KR 101686753B1 KR 1020150158796 A KR1020150158796 A KR 1020150158796A KR 20150158796 A KR20150158796 A KR 20150158796A KR 101686753 B1 KR101686753 B1 KR 101686753B1
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- G—PHYSICS
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- G02B1/02—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of crystals, e.g. rock-salt, semi-conductors
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
Abstract
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverse opal optical structure, a manufacturing method thereof, and an optical sensor using the inverse opal optical structure. More particularly, the present invention relates to an inverse opal optical structure capable of controlling a UV exposure intensity and an exposure area, And an optical sensor using the same.
Although a single particle structure is used in the present invention, a multicolor micropattern can be realized by a simple process such as vapor deposition, heat treatment, ultraviolet irradiation, or the like.
The present invention can produce a polymer frame having a fine pattern with a photoresist, thereby increasing the resolution of the optical structure. Also, since the optical structure of the present invention has a high fraction of the air cavity and maintains a uniform shape of the cavity even during shrinkage, high reflectivity and various reflection spectra can be realized.
The present invention can widely control the temperature range in which the structure color changes by controlling the kinds of the photoresist used as the polymer frame or by controlling the ultraviolet irradiation region and the irradiation amount.
Description
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverse opal optical structure, a manufacturing method thereof, and an optical sensor using the inverse opal optical structure. More particularly, the present invention relates to an inverse opal optical structure capable of controlling a UV exposure intensity and an exposure area, And an optical sensor using the same.
A photonic crystal is a material having a photonic bandgap due to a periodic change in dielectric constant at half the wavelength of light. At this time, the photons having the energy corresponding to the photonic band gap can not propagate into the photonic crystal due to the very low density of the photonic crystal. If the photonic band gap is present in the visible light region, the photonic band appears as a reflection color.
The regular arrangement of the colloid particles is the color corresponding to the band gap of the photonic crystal, which is represented by the same principle as that of the reflection color. The color of the colloidal photonic crystal is determined by the refractive index of the colloid and the background material, the crystal structure, the size of the particles, the spacing between the particles, and the like. Therefore, by controlling this, a photonic crystal having a desired reflection color can be manufactured.
Opals are minerals that are mined into natural stones. Opal nanostructures have a structure in which multiple spheres of dense spherical particles with diameters of tens to hundreds of nanometers are stacked in multiple layers. The nanostructure of the opal reflects a certain color depending on the size and arrangement of the spherical particles. The nanostructure mimics the nanostructure of the opal.
In particular, arranging nanometer-sized particles in opposition to opal nanostructures is referred to as an " inverse opal structure ", which is a material having photonic crystals, It can be applied to almost all fields using light such as optical fiber, optical waveguide, optical integrated circuit, photocatalyst, and optical sensor.
Colloidal crystals, such as inverted opals, have a long-range order in three-dimensional space. The periodic modulation of the reflex index by controlling the particle size or the particle spacing can change the photonic bandgap through the interaction with light at the wavelength of the double lattice space. Light with wavelengths within the bandgap is not introduced into the structure and is therefore selectively reflected to provide iridescent structural colors in the visible range. The structural color can be controlled by changing the stimulus - reactivity of the lattice parameter or reflection index without fading. For this reason, structural colors can be used for aesthetics, color measurement sensors, and so on. These optical structures such as multicolor micropatterns or continuous modulation (discoloration) of colors can be applied to display devices, anti-falsification, optical filters and the like.
Several methods for producing such multicolor micropatterns have been attempted. For example, a monochromatic optical film can be locally swollen by the solvent to provide a color pattern. However, such a pattern is disadvantageous when the solvent disappears and resolution is also limited. The spherical dome of the colloidal crystal by ink jet printing can provide high resolution, but there is a problem that the adjacent voids (spaces) between the dome are relatively large to provide a low reflectance.
It is also known that inverse opal structures with multicolor micropatterns can be lithographically fabricated using template particles of different sizes. There is a problem in that it is very complicated and precise control is required to manufacture a reverse opal structure using particles having various sizes.
Japanese Patent Laid-Open No. 10-1526084 discloses a temperature sensitive composite photonic crystal. In this patent, a method of changing a band gap by filling a pore of a reverse opal structure with a filler sensitive to a temperature change is disclosed. However, the above-mentioned registered patent has a relatively narrow temperature sensing range of 10 to 22 degrees, a very low reflectance due to the presence of a filler, and limitations in showing structural colors of various colors due to reflection spectra.
The present invention provides a method of easily embodying a multicolor micropattern using a monopole inverse opal structure.
The present invention provides a reverse opal structure capable of sensing a wide temperature range while maintaining high reflectivity and high resolution.
In one aspect,
A plurality of air cavities of uniform size regularly arranged in multiple layers; And an inverse opal optical structure surrounding the cavity and irreversibly contracting when exposed to a temperature above a glass transition temperature and having a degree of shrinkage defined by the exposed ultraviolet radiation dose, the structure being characterized in that the polymeric frame is non- Is related to the inverse opal optical structure in which the structural color (wavelength of the reflection spectrum) is blue-shifted.
In another aspect
Forming a photoresist layer on the substrate;
Forming nanoparticles in an opal structure on the photoresist layer;
Applying heat to the photoresist layer to embed the nanoparticles in the photoresist layer; And
And removing the nanoparticles. ≪ Desc /
In yet another aspect,
A plurality of air cavities of regular size arranged in multiple layers; And an inverse opal optical sensor including a polymer frame surrounding the cavity and irreversibly contracted when exposed to a temperature higher than a glass transition temperature and a shrinkage degree determined by an exposed ultraviolet irradiation amount, Lt; RTI ID = 0.0 > opaque < / RTI > optical sensor that records at least one of temperature and time with a discolored structure color.
Although a single particle structure is used in the present invention, a multicolor micropattern can be realized by a simple process such as vapor deposition, heat treatment, ultraviolet irradiation, or the like.
The present invention can produce a polymer frame having a fine pattern with a photoresist, thereby increasing the resolution of the optical structure. Also, since the optical structure of the present invention has a high fraction of the air cavity and maintains a uniform shape of the cavity even during shrinkage, high reflectivity and various reflection spectra can be realized.
The present invention can widely control the temperature range in which the structure color changes by controlling the kinds of the photoresist used as the polymer frame or by controlling the ultraviolet irradiation region and the irradiation amount.
1 is a schematic view of an inverse opal structure of the present invention.
Fig. 2 shows a cross section taken along line A-A 'in Fig.
Figure 3 shows that the inverse opal structure of the present invention is shrunk by heat and thus the reflection color changes.
Fig. 4 shows a method of manufacturing the optical structure of Fig.
Figure 5 shows a method for implementing two colors with a single inverse opal structure using a negative photoresist.
FIG. 6 shows a method of implementing multiple colors with a single inverse opal structure using a negative photoresist.
7 shows a method of implementing two colors with a single inverse opal structure using a positive photoresist.
Figure 8 shows a method of implementing multiple colors with a single inverse opal structure using positive photoresist.
9 is a graph comparing the SEM image (a) of the cross section and the optical image of the surface (FIG. 9) after applying the inverse opal structure prepared without UV irradiation in Example 1 at a temperature of 40 degrees for 0 minute, 3 minutes, 5 minutes, b), and (c) is a spectrum showing the reflectance according to the wavelength.
FIGS. 10A and 10B show changes with time of the stop band wavelength and air fraction when the heat treatment is performed at 35.degree. C., 40.degree. C., and 45.degree. C. to the inverse opal structure produced without UV irradiation in Example 1. FIG. c and d are the optical micrographs and the reflectance spectra of the surface of the optical structure prepared in Example 1, wherein the optical structure was irradiated with a UV dose of 60 mJ /
11 is an optical microscope photograph of an inverse opal film prepared in Example 2 and continuously heat-treated at 35 degrees for a predetermined time, and an inverse opal film was taken at each time.
12 shows an optical microscope photograph of the inverse opal film prepared in Example 3. Fig.
13 compares the stability of the pattern structure of Example 4. Fig.
The present invention relates to an inverse opal optical structure capable of a multicolor pattern in a single particle structure. Embodiments of the present invention will be described in detail.
FIG. 1 is a schematic view of the inverse opal structure of the present invention, and FIG. 2 is a cross-sectional view taken along the line A-A 'in FIG.
Referring to FIG. 1, the inverse opal structure of the present invention includes an
The air cavities are a plurality of uniformly sized pores arranged in multiple layers regularly. Opal nanostructures have a structure in which multiple spheres of dense spherical particles with diameters of tens to hundreds of nanometers are stacked in layers. The air cavity is a spherical empty space formed by removing the spherical nanoparticles. As the fraction of the cavity increases, the difference in the refractive index increases, so that the scattered amount of light increases, thereby exhibiting a high reflectance.
There is no particular limitation on the volume fraction of the cavity relative to the entire structure. However, it is preferable that the cavity has a volume fraction enough to exhibit a specific structural color due to light scattering. For example, if the volume fraction of the cavity is about 20% or more, the structural color can be reflected.
Also, the volume fraction of the cavity decreases as the inverse opal structure shrinks. For example, as described below, embodiments of the present invention can reduce the fraction of the initial cavity by 74% and by 20% as the structure shrinks.
The
The
Figure 3 shows that the inverse opal structure of the present invention is shrunk by heat and thus the reflection color changes.
Referring to FIG. 3, when the polymer frame is exposed to a temperature higher than the glass transition temperature of the polymer, the polymer frame shrinks downward (perpendicular to the substrate direction) as it changes from a solid state to a viscous state. However, the polymer frame is formed on the
Referring to FIG. 3, the initial distance d0 between the cavity and the cavity is reduced to d by the thermal contraction process. That is, in the inverse opal structure, as the interval of the cavity is changed, the photonic bandgap is changed at the wavelength of the lattice space, and the reflection spectrum wavelength range that is reflected as a result is also changed. Further, as the interval of the cavity is changed, the volume fraction of air and photoresist is changed by conserving the mass, and the effective refractive index is also changed.
That is, referring to FIG. 3, the inverse opal optical structure before being exposed to the temperature (heat) above the glass transition temperature reflects light in the red wavelength range, but is exposed to heat to reduce the optical structure to reflect light in the blue wavelength range.
The
Since the photoresist can form a fine pattern, it can provide a high resolution pattern. In the case of SU-8, it is a typical negative photoresist that is commercially or commonly used. Using a photoresist can achieve a high aspect ratio pattern and easily depress the photoresist of various thicknesses. In order to minimize the interfacial energies between SiO2 particles, air, and SU-8, SiO2 particles enter the SU-8 during the embedding process in the aspect of reversed photonic crystal manufacturing, , Which is easier and simpler to approach in the process.
The degree of shrinkage of the optical structure is determined by the dose of ultraviolet light irradiated on the polymer frame during the production of the structure.
Referring to an embodiment to be described later, when the optical structure is a negative photoresist, the contraction rate of the optical structure is relatively reduced when the amount of exposed ultraviolet light is increased. That is, when the exposure dose of ultraviolet light is increased in the optical structure, the cross-linking density of the polymer increases and the temperature (glass transition temperature) at which the polymer structure begins to shrink increases, and the shrinkage rate also decreases relatively.
On the other hand, when the optical structure is a positive photoresist, the contraction rate of the optical structure increases relatively when the amount of exposed ultraviolet light increases. In the following, mainly, the case where the optical structure is a negative photoresist will be mainly described.
On the other hand, the degree of shrinkage of the optical structure depends on the exposure temperature and the exposure time. Here, the exposure temperature and time indicate the temperature and time after exposure of the optical structure. The temperature is usually a temperature higher than the glass transition temperature, and the higher the temperature, the more shrinkage occurs. Also, the longer the exposure time, the greater the anisotropic shrinkage of the structure and hence the closer to the structure chromaticity blue. In the present invention, the time and temperature at which the optical structure is exposed to the thermal environment can be measured through the degree of shrinkage of the optical structure.
That is, when the structure is exposed to a temperature higher than the glass transition temperature of the polymer, the structural color (reflection spectrum) of the ultraviolet region is exposed to the glass transition temperature according to the amount of exposed ultraviolet ray, the exposure temperature, It can be blue transition compared to the structure color of the previous ultraviolet region.
As used herein, the terms " ultraviolet region ", " first ultraviolet region ", " second ultraviolet region ", " n ultraviolet region "
Fig. 4 shows a method of manufacturing the optical structure of Fig. Referring to FIG. 4, the method of the present invention includes a photoresist layer forming step, a nanoparticle forming step, an embeded step, and a nanoparticle removing step.
The photoresist layer is formed on the substrate. There is no particular limitation on the type of the substrate. The substrate may be a glass substrate, a polymer substrate, or a transparent substrate.
And may be formed using the photoresist. The photoresist may be positive or negative and the negative photoresist may be SU-8, KMPR, UVN-30, ma-N 1400, ma-N 2400, AZ 5214E, AZ 9260, etc.).
The nanoparticle forming step is a step of forming nanoparticles into an opal structure on the photoresist layer. The nanoparticles may be those which can be dissolved and removed in a specific solution as described later. For example, the nanoparticles may be silica nanoparticles, zinc oxide nanoparticles, titanium dioxide nanoparticles, tin dioxide nanoparticles, polystyrene (PS) nanoparticles, polymethylmethacrylate (PMMA) nanoparticles. Preferably, SiO2 particles can be used.
The step of embedding is a step of applying heat to the photoresist layer to precipitate the nanoparticles into the photoresist layer. By this step, the nanoparticles are surrounded by the photoresist layer, more specifically, because the silica particles penetrate into the SU-8 to minimize surface energy.
The embedding step is a step of applying heat at a temperature higher than the glass transition temperature of the photoresist layer.
The step of removing the nanoparticles is a step of selectively removing only the nanoparticles embedded in the photoresist layer. In the step of removing nanoparticles, a solution capable of selectively dissolving the nanoparticles may be used. When the solution is silica, HF or NaOH may be used.
The method may further include irradiating ultraviolet light after the embedded step.
After the nanoparticle-removing step, the optical structure may be further irradiated with ultraviolet light to enhance pattern stability. When the ultraviolet rays are irradiated and the heat treatment is performed for a predetermined time, the color of the optical structure color can be maintained for a predetermined time. For example, the method may be heat treated at 900 mJ / cm2 and then at 70 degrees for 10 minutes.
Characterized in that the inverse opal optical element
The method can control the rate of shrinkage of the polymer frame by controlling the amount of ultraviolet radiation. As a result, the method of the present invention can control the color shift (blue transition start) temperature and the blue transition speed of the structural color. More specifically, the temperature at which the glass transition temperature (Tg) varies according to the amount of ultraviolet light irradiated to the polymer frame during the manufacture of the structure, and accordingly, the temperature at which the shrinkage starts is varied.
For example, when the structure is a negative photoresist, if the ultraviolet ray irradiation amount is increased, the crosslinking density of the polymer frame is high, and the Tg becomes high. Also, if the amount of ultraviolet radiation is increased, the shrinkage rate of the frame relatively decreases when exposed at a temperature higher than the glass transition temperature. As a result, adjusting the ultraviolet radiation dose can control not only the temperature at which the discoloration of the structural color begins, but also the color of the structural color - consequently, the blue transition range (the discoloration range of the structural color) and the blue transition speed.
The method of manufacturing the inverse opal structure of the present invention can be variously implemented. For example, the method of the present invention includes forming nanoparticles in an opal structure on a substrate; Filling a photoresist layer in a gap between the nanoparticles; Irradiating ultraviolet rays; And removing the nanoparticles.
First, a solution containing nanoparticles may be coated on a substrate to form an opal structure layer. The solvent may be removed therefrom to form an opal structure of the silica nanoparticles. Also, the opal structure can be formed by immersing the substrate in a solution in which the nanoparticles are dispersed and slowly raising the substrate.
Next, a photoresist layer can be filled in the pores between the nanoparticles. The photoresist polymer is filled between the pores and a predetermined heat is applied.
Then, the crosslink density of the photoresist layer can be controlled by irradiating ultraviolet rays. That is, as described above, the Tg of the polymer structure can be controlled by adjusting the amount of ultraviolet irradiation.
The present invention removes the nanoparticles to form an optical structure of an inverse opal structure. The removal of the nanoparticles can be described in the above description.
In the present invention, an opal structure is formed by using nanoparticles injected in the process of manufacturing the inverse opal structure in the same kind and size. As used herein, the term " single inverse opal structure " refers to an inverse opal structure fabricated from nanoparticles of the same type and size. As a result, a single inverse opal structure has cavities of the same size and spacing.
Generally, conventionally, multicolor structure colors are provided by varying kinds of particles or size intervals, but in the present invention, two colors or multiple colors can be realized with a single inverse opal structure.
5 shows a method of implementing two colors with a single inverse opal structure using a negative photoresist. Referring to FIG. 5, in the ultraviolet ray irradiation step, an inverted opal structure can be manufactured by separately irradiating an ultraviolet (irradiated) region with a non-irradiated region using a photomask and removing nanoparticles (SiO2). The inverse opal structure includes an ultraviolet ray region irradiated with ultraviolet rays and a non-irradiated region not irradiated.
Referring to FIG. 5, the inverse opal structure having two divided regions shows a single structure color before being exposed to a temperature higher than the glass transition temperature. However, when the structure is exposed to Tg or more, the ultraviolet region and the non-ultraviolet region exhibit different structure colors. More specifically, when exposed to Tg or higher, the non-ultraviolet region shrinks more sharply than the ultraviolet region, so that the structural color of the non-ultraviolet region exhibits a more blue-colored structure color than the ultraviolet region.
In Fig. 5, the ultraviolet region can control the degree of blue transition by the exposed dose. For example, when the ultraviolet exposure dose is exposed to a predetermined amount or more, the structure may not shrink even when exposed to a temperature higher than the Tg (the glass transition temperature of the structure before ultraviolet irradiation) due to the high crosslinking density. The Tg varies depending on the irradiation dose of the earth. The shrinkage occurs at a temperature higher than Tg, and the structure is maintained at a temperature lower than Tg. At the temperature below Tg, the initial structural color is maintained in the ultraviolet region.
FIG. 6 shows a method of implementing multiple colors with a single inverse opal structure using a negative photoresist. Referring to FIG. 6, the ultraviolet light irradiation step may include irradiating the ultraviolet first (irradiated) region, the second (irradiated) region and the non-ultraviolet (irradiated) region separately by using a photomask, The inverse opal structure having a multicolor pattern can be manufactured.
The inverse opal structure includes a first ultraviolet region, a second ultraviolet region and a non-ultraviolet region. Further, the inverse opal structure may include an n-th ultraviolet region and a non-ultraviolet region from the first ultraviolet region.
Here, n is 2 to 10, and the amount of ultraviolet ray exposure increases from the first ultraviolet region toward the nth ultraviolet region. Therefore, as the shrink width of the structure decreases from the first ultraviolet region to the n ultraviolet region, the blue transition phenomenon of the structural color is also lowered.
Also, the structure may be a multi-color optical structure in which the structure colors of the non-ultraviolet region, the first ultraviolet region, and the nth ultraviolet region are different depending on the amount of exposed ultraviolet ray, the exposure temperature, or the exposure time.
Figure 7 shows a method of implementing two colors with a single inverse opal structure using a positive photoresist. 7 shows that contraction of the ultraviolet ray irradiated region irradiated with ultraviolet rays occurs more sharply than that of the non-irradiated region, and thus, the structure color of the ultraviolet ray irradiated region is more blue transitioned than the non-ultraviolet ray region Represents the structural color.
8 shows a method of implementing a multicolor with a single inverse opal structure using a positive photoresist. Referring to FIG. 8, the ultraviolet ray irradiation step may include irradiating the ultraviolet first (irradiated) region, the second (irradiated) region and the non-ultraviolet (irradiated) region separately by using a photomask, The inverse opal structure having a multicolor pattern can be manufactured.
The inverse opal structure includes a first ultraviolet region, a second ultraviolet region and a non-ultraviolet region. Further, the inverse opal structure may include an n-th ultraviolet region and a non-ultraviolet region from the first ultraviolet region.
The amount of ultraviolet ray exposure increases from the first ultraviolet region toward the nth ultraviolet region. Therefore, as the shrink width of the structure increases from the first ultraviolet region to the n ultraviolet region, the blue transition phenomenon of the structural color increases.
In another aspect, the present invention may be an inverse opal optical sensor that irreversibly records temperature.
The optical sensor includes a plurality of air cavities of regular size arranged in a regularly multi-layered arrangement; And a polymer frame which surrounds the cavity and irreversibly shrinks when exposed to a temperature higher than the glass transition temperature, and the shrinkage degree is determined by the exposed ultraviolet radiation dose.
Since the polymer frame is not restored to its original shape after the polymer frame is shrunk but the discolored structure color is maintained, the time and temperature of exposure to the thermal environment can be recorded.
For example, ultraviolet rays may be irradiated to the polymer in an appropriate amount such that the structure is shrunk at 30 DEG C or higher by using the same structure as shown in Fig.
Referring to FIG. 5, the non-ultraviolet region may be shrunk at 30 ° C to be discolored, and the ultraviolet region may be irradiated with an appropriate amount of ultraviolet light so as to be discolored at 35 ° C. The structural colors in the non-ultraviolet region and the ultraviolet region may be different from each other. In this case, if the color changes only in the non-ultraviolet region, the ambient temperature of the optical structure is in the range of 30 to less than 35 degrees. In addition, when the color of both the non-ultraviolet region and the ultraviolet region is discolored, it can be understood that the ambient temperature is not less than 35 degrees.
Likewise, if the ultraviolet ray irradiation area is set to 1 to n, the ambient temperature can be further segmented and recorded.
The optical structure may be applied not only to a temperature sensor but also to a display device, an anti-fake device, an optical filter, and the like.
Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.
Example 1. Preparation of the optical structure of Figure 1
SU-8 was deposted on a silicon wafer substrate by spincoating at 2000 rpm for 30 seconds. An oxygen plasma process was performed on the SU-8 film to enhance the affinity of the silica particles with the dispersed water.
Subsequently, the SU-8 film was immersed in the solution in which the silica particles were dispersed in 2 weight percent, and then the water was drawn at a rate of 0.5 micrometers / second. The silica particles were heated to 120 DEG C to embed the SU-8 film. The silica / photoresist mixed film was irradiated with ultraviolet irradiation at 0, 60, 120, 180, 225 mJ / cm 2 Respectively. If desired, the desired UV dose can be investigated using a photomask. The following Examples 2, 225 mJ / cm 2 and dropped examined by, for example 3 per the
Example 2
As in FIG. 5, the same procedure as in Example 1 was performed except that ultraviolet light was irradiated using a photomask.
Example 3
6, the first ultraviolet ray irradiation was performed using the first photomask, and the second ultraviolet ray irradiation was performed using the second photomask.
Example 4
(30 mJ / cm 2 ) was irradiated using a first photomask and irradiated with a second ultraviolet ray (60 mJ / cm 2 ) using a second photomask as in Example 3. Two patterns were fabricated under these conditions.
One of the two patterns was exposed at 70 degrees for 1 second without further UV irradiation (Fig. 13b). The other one was irradiated with UV at 900 mJ /
9 is a graph comparing the SEM image (a) of the cross section and the optical image of the surface (FIG. 9) after applying the inverse opal structure prepared without UV irradiation in Example 1 at a temperature of 40 degrees for 0 minute, 3 minutes, 5 minutes, b). Referring to FIG. 9, during the heat treatment process, the inverse opal structure is vertically compressed, and the structural color changes from red to blue to blue. When a sufficient time has elapsed, the porous structure is completely lost, and as a result, the optical effect is also lost. FIG. 9C is a spectrum showing the reflectance according to the wavelength generated in the process of heat treatment at 40 degrees for 0 to 10 minutes.
Referring to FIG. 9A, it can be confirmed that the air cavity structure contracts and deforms from a spherical shape to a disk shape after a lapse of time.
Referring to FIG. 9C, the wavelength changes to blue as the heat treatment time elapses, and the reflectance is still high even in the case of blue. When 10 minutes passed, the optical characteristics of the structure were lost. Referring to FIG. 9C, the present invention shows that by controlling the heat treatment of the inverse opal, it is possible to realize wavelengths of all visible light wavelengths even when a single size particle is used as a template.
FIGS. 10 (a) and 10 (b) show the time-dependent variation of the stop band wavelength and the air fraction in the case of heat treatment at 35.degree. 10A and 10B show that the irreversible strain rate of the polymer inverse opal structure is affected by the heat treatment temperature. The graphs of a and b in Fig. 10 show almost similar patterns. In FIGS. 10A and 10B, the higher the annealing temperature, the more rapidly the blue transition occurs, indicating that the inverse opal structure is vertically reduced very rapidly.
10C and 10D are optical microphotographs of the surface of the optical structure prepared in Example 1, in which the UV irradiation amount is 60 mJ / cm < 2 > and the optical structure is exposed at 40 degrees for 0 to 180 minutes. It can be seen that the blue transition of the wavelength is considerably delayed as compared with c (when UV irradiation is not performed) in FIG. 9. However, the reflectance remained high.
FIG. 10E shows stop band wavelengths according to the time of the inverse opal structure when the UV irradiation amount is irradiated at 0, 60, 120, 180, and 225 mJ /
11 (a) is an optical microscope photograph of the inverse opal film prepared in Example 2, which was continuously heat-treated at 35 degrees for a predetermined time, and the reverse opal film was photographed at each time. Referring to FIG. 11A, the lines exposed to UV are maintained in red despite the lapse of time, but the base portions that are not exposed to UV change from red to orange, green, and blue, and eventually do not show color. In other words, the lines exposed to UV are irradiated with more than critical UV amount to make the polymer have a stable structure, and it shows that the structural color is stably provided without discoloration for a long time.
11 (b) is a cross-sectional view of a reverse opal film produced by selectively irradiating UV light through a photomask having a letter "A" and a frame of "Photonic Crystal" as a transparent region, followed by heat treatment at a temperature of 45 ° C. for a predetermined time, Is an optical microscope photograph of a reverse opal film. Referring to FIG. 11 (b), the characters and the border portions exposed to UV remain red even though the time elapses, but portions not exposed to UV change from red to orange, green, and blue, can not do it. Referring to FIG. 11 (c), when the heat treatment is not performed at the glass transition temperature, the red wavelength is maintained, but the blue transition occurs and the reflectivity decreases as the heat treatment time elapses. In addition, the spectrum of the character color is maintained in red color, but the background color is blue transition due to a new peak.
12 shows an optical microscope photograph of the inverse opal film prepared in Example 3. Fig.
12 (a) is an optical photograph of a film heat-treated at 40 ° C. for 2 minutes and 4 minutes after UV irradiation. 12 (a) shows a photomask used for the first and second UV irradiation, and FIG. 12 (b) shows an optical photograph of a film heat-treated at 40 degrees for 2 minutes and 4 minutes after UV irradiation.
Referring to FIG. 12 (b), a quadrangle (in a unit of four units) of a photograph that is heat treated for 2 minutes shows one green, two orange red, and one red. Four minutes heat-treated squares show blue, two green, and one red. In Fig. 12D, a three-color structure is shown as a background color, a tree, and a fruit.
FIG. 12 shows that a multicolor micropattern can be produced by using a photomask and varying the amount of UV irradiation even though a single particle structure (a single inverse opal structure as in the present invention) is used.
Fig. 13 shows the stability of the pattern structure of Example 4. Fig. 13 (b) shows that the structure color disappears immediately after the exposure at 70 degrees for 1 second, but in the case of FIG. 13 (c), the optical characteristics and structure of the photonic crystal can be maintained even after a long time.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.
Claims (20)
When the structure is exposed to a temperature higher than the glass transition temperature of the polymer, the structure of the ultraviolet region before the structural color (reflection spectrum) of the ultraviolet region is exposed to the glass transition temperature according to the amount of exposed ultraviolet ray, the exposure temperature, Wherein the blue opaque color is blue compared to the color.
Wherein the structure is a two-color optical structure having different structural colors (wavelengths of a reflection spectrum) of an ultraviolet region and a non-ultraviolet region when the structure is exposed to a glass transition temperature of the polymer or higher.
Wherein the structural color of the non-ultraviolet region, the first ultraviolet region, and the nth ultraviolet region are different from each other when the structure is exposed to a glass transition temperature of the polymer.
Here, n is 2 to 10, and the amount of ultraviolet ray exposure increases from the first ultraviolet region toward the nth ultraviolet region.
Forming nanoparticles in an opal structure on the photoresist layer;
Applying heat to the photoresist layer to embed the nanoparticles in the photoresist layer;
Irradiating ultraviolet rays; And
And removing the nanoparticles.
A plurality of air cavities of uniform size regularly arranged in multiple layers; And an inverse opal optical structure surrounding the cavity and irreversibly contracting when exposed to a temperature above a glass transition temperature and having a degree of shrinkage defined by the exposed ultraviolet radiation dose, the structure being characterized in that the polymeric frame is non- Wherein the structure color (wavelength of the reflection spectrum) is blue-shifted when the light is shrunken.
Filling a photoresist layer in a gap between the nanoparticles;
Irradiating ultraviolet rays; And
And removing the nanoparticles.
A plurality of air cavities of uniform size regularly arranged in multiple layers; And an inverse opal optical structure surrounding the cavity and irreversibly contracting when exposed to a temperature above a glass transition temperature and having a degree of shrinkage defined by the exposed ultraviolet radiation dose, the structure being characterized in that the polymeric frame is non- Wherein the structure color (wavelength of the reflection spectrum) is blue-shifted when the light is shrunken.
Here, n is 2 to 10, and the amount of ultraviolet exposure increases from the first ultraviolet region toward the nth ultraviolet region.
Wherein the non-ultraviolet region and the ultraviolet region record temperatures at different structure colors that are discolored at a predetermined temperature or higher.
Here, n is 2 to 10, and the amount of ultraviolet ray exposure increases from the first ultraviolet region toward the nth ultraviolet region.
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| KR20200068962A (en) * | 2018-12-06 | 2020-06-16 | 한국에너지기술연구원 | Hierarchical metal-organic polyhedra, preparation method thereof and photonic crystal sensor comprising the same |
| KR20210051457A (en) * | 2019-10-30 | 2021-05-10 | 한국과학기술원 | Thermal Condition Recording Method and Thermal Condition Recording System Using Inverse Opal Optical Structure |
| KR20220150153A (en) * | 2021-05-03 | 2022-11-10 | 서울대학교산학협력단 | Method of forming polymer inverse opal structure, imaging device comprising the polymer inverse opal structure, and method of forming the imaging device |
| KR20230022349A (en) | 2021-08-06 | 2023-02-15 | 금오공과대학교 산학협력단 | Surface-Enhanced Raman Spectroscopy(SERS) Sensor with Inverse-opal structure and their manufacturing method |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20200068962A (en) * | 2018-12-06 | 2020-06-16 | 한국에너지기술연구원 | Hierarchical metal-organic polyhedra, preparation method thereof and photonic crystal sensor comprising the same |
| KR102192316B1 (en) * | 2018-12-06 | 2020-12-18 | 한국에너지기술연구원 | Hierarchical metal-organic polyhedra, preparation method thereof and photonic crystal sensor comprising the same |
| KR20210051457A (en) * | 2019-10-30 | 2021-05-10 | 한국과학기술원 | Thermal Condition Recording Method and Thermal Condition Recording System Using Inverse Opal Optical Structure |
| KR102265009B1 (en) * | 2019-10-30 | 2021-06-15 | 한국과학기술원 | Thermal Condition Recording Method and Thermal Condition Recording System Using Inverse Opal Optical Structure |
| KR20220150153A (en) * | 2021-05-03 | 2022-11-10 | 서울대학교산학협력단 | Method of forming polymer inverse opal structure, imaging device comprising the polymer inverse opal structure, and method of forming the imaging device |
| KR102506727B1 (en) * | 2021-05-03 | 2023-03-07 | 서울대학교산학협력단 | Method of forming polymer inverse opal structure, imaging device comprising the polymer inverse opal structure, and method of forming the imaging device |
| KR20230022349A (en) | 2021-08-06 | 2023-02-15 | 금오공과대학교 산학협력단 | Surface-Enhanced Raman Spectroscopy(SERS) Sensor with Inverse-opal structure and their manufacturing method |
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