KR20230028616A - Upconversion plasmonic structure comprising quasi-periodic metal nanostructure - Google Patents

Abstract

The present invention relates to an upconversion plasmonic structure including a quasi-periodic metal nanostructure, and more specifically, to an upconversion plasmonic structure including a quasi-periodic metal nanostructure, wherein optically and kinetically enhanced reversible switching control of photochemical isomers is possible. The upconversion plasmonic structure includes: a metal film layer; an insulating layer formed on the metal film layer; and a quasi-periodic metal nanostructure formed on the insulating layer.

Description

Upconversion plasmonic structure containing quasi-periodic metal nanostructure {UPCONVERSION PLASMONIC STRUCTURE COMPRISING QUASI-PERIODIC METAL NANOSTRUCTURE}

The present invention relates to an upconversion plasmonic structure including a quasi-periodic metal nanostructure capable of controlling reversible switching of photochemical isomers based on a single wavelength, and a photochemical switching device including the same.

The photoisomeric organic material refers to a material having a photoisomerization property in which the molecular structure changes according to a specific wavelength, and the chemical structure of the molecule changes according to the wavelength of light irradiated as shown in FIG. 1.

In the last 20 years, photoisomeric organics have attracted attention due to their potential applications in various electronic, spectroscopic and optical systems. Among them, due to their relatively fast reaction rate, high optical isomer quantum yield, and high stability, studies on diaryl ethene-based molecules are being actively conducted (O. Nevskyi et al., Angew. Chem. Int. Ed. 2016, 55, 12698, D. Kim et al., Adv. Opt. Mater. 2018, 6, 1800678, G. Naren et al., Nat. Commun. 2019, 10, 3996).

However, in order to practically apply photoisomeric organic materials, reversible photoisomerization control of photoisomeric organic materials is required. More than one optical path of light must be precisely matched. However, since it is optically very difficult to match optical paths of ultraviolet and visible light, which have significantly different wavelength ranges, there are limitations in the application of photoisomeric organic materials.

As an alternative to the above problem, a method of controlling the photoisomerization reaction of photoisomeric organic materials using the photo-switching characteristics of rare earth metal-based upconverting nanoparticles (UCNPs) has been proposed ( P. Dawson et al., J. Am. Chem. Soc. 2018, 1440, 5714, and A. Teitelboim et al., J. Phys. Chem. C 2019, 123, 2678). This method utilizes an upconversion property in which upconverting nanoparticles absorb photons in a long-wavelength region such as the near-infrared region several times and emit photons in a short-wavelength region such as a single ultraviolet or visible region (J. Lai et al., Angew. Chem. Int. Ed. 2014, 53, 14419 and K. Zheng et al., Adv. Mater. 2018, 30, 1801726).

Figure 2 schematically shows the optical properties of upconverting nanoparticles (UCNPs) as an example of upconverting nanoparticles. Upconversion nanoparticles selectively emit wavelengths of photons emitted from upconversion nanoparticles in the ultraviolet or visible region by adjusting the intensity of incident near-infrared (NIR) light through chemical composition design. can be made to do so.

By using the photo-switching characteristics of the up-conversion nanoparticles, it is possible to clearly control the effective light absorption area of the photoisomeric organic material and overcome the limitations of wavelength selection.

However, despite these promising prospects, upconversion nanoparticles have fundamental limitations in their use as a medium for photochemical reactions due to their low luminescence quantum yield and low light absorption efficiency (S. Fischer et al., Nano Lett. 2016, 16 , 7241, N. J. J. Johnson et al., J. Am. Chem. Soc. 2017, 139, 3275, and M. D. Wisser et al., Nano Lett. 2018, 18, 2689).

The present invention aims to overcome the problems of low light emission quantum yield and low light absorption efficiency of conventional upconverted nanoparticles, and apply them to photoisomerized organic compounds to be applied as a photochemical switching medium.

In order to achieve the above object, an upconversion plasmonic structure according to an aspect of the present invention includes a metal film layer, an insulating layer formed on the metal film layer, and a quasi-periodic metal nanostructure formed on the insulating layer. The insulating layer includes upconverting nanoparticles therein.

The quasi-periodic metal nanostructure may be formed by transferring the periodic metal nanostructure onto the insulating layer twice at different rotation angles.

The periodic metal nanostructure may be a hexagonal array metal nanostructure, and specifically, may be formed by transferring the hexagonal array metal nanostructure twice with a rotation angle difference of 5° to 40°. there is.

The insulating layer may have a thickness of 1 nm to 1 μm.

The upconversion nanoparticles included in the insulating layer may be formed as a monolayer.

Each of the metal film layer and the quasi-periodic metal nanostructure may be made of one selected from the group consisting of gold, silver, aluminum, copper, platinum, and alloys thereof.

A photochemical switching device according to another aspect of the present invention includes the present up-conversion plasmonic structure and a photoisomeric organic material layer.

Specifically, the photoisomeric organic material layer may be formed on the quasi-periodic metal nanostructure of the upconversion plasmonic structure.

A nonvolatile optical memory device according to another aspect of the present invention includes the photochemical switching device.

A fluorescence microscope according to another aspect of the present invention includes the photochemical switching element.

A transistor according to another aspect of the present invention includes the photochemical switching element.

An upconversion plasmonic structure manufacturing method according to another aspect of the present invention includes (S1) stacking an insulating layer including upconversion nanoparticles on a metal film layer; (S2) firstly vacuum-depositing a metal thin film on the transfer frame on which protrusions are periodically formed at a constant height on the base portion; (S3) forming a periodic metal nanostructure by firstly transferring the metal thin film deposited on the protruding portion of the transfer frame formed in step S2 to an upper portion of the insulating layer; (S4) vacuum depositing a second metal thin film on the transfer frame; and (S5) rotating the metal thin film deposited on the protruding portion of the transfer frame formed in step S4 so as not to coincide with the first transfer. and forming a quasi-periodic metal nanostructure by performing secondary transfer on top of the periodic laminate formed in the above.

In the transfer frame, protrusions having a certain height may be periodically formed in a hexagonal array on the base portion.

The secondary transfer of the step S5 may have a rotation angle difference of 5° to 40° from the primary transfer of the step S3.

The transfer frame may have a cylindrical shape of a protrusion having a certain height on the base portion.

The first transfer of step S3 may be performed by a soft baking process, and the second transfer of step S5 may be performed by a hard baking process.

A photochemical switching device manufacturing method according to another aspect of the present invention includes (S1) stacking an insulating layer including upconversion nanoparticles on a metal substrate layer; (S2) firstly vacuum-depositing a metal thin film on the transfer frame on which protrusions are periodically formed at a constant height on the base portion; (S3) forming a periodic metal nanostructure by firstly transferring the metal thin film deposited on the protruding portion of the transfer frame formed in step S2 to an upper portion of the insulating layer; (S4) secondary vacuum deposition of a metal thin film on the transfer frame; (S5) The metal thin film deposited on the protrusion of the transfer frame formed in step S4 is rotated so as not to coincide with the first transfer, and the second transfer is performed on the upper part of the periodic stack formed in step S3 to form a quasi-periodic metal nanostructure. and (S6) stacking a photo-isomeric organic material layer on top of the quasi-periodic metal nanostructure.

The upconversion plasmonic structure according to one aspect of the present invention is capable of activating a resonance mode in a broadband wavelength including both ultraviolet and visible regions substantially necessary for a photoisomeric reaction through a broadband resonance structure.

In addition, the photochemical switching device according to one aspect of the present invention includes the up-conversion plasmonic structure and is capable of optically and kinetically improved reversible photoisomerization.

Therefore, the photochemical switching device of the present invention improves the applicability to non-volatile optical memory devices, super-resolution fluorescence microscopes, etc. through the control of the isomerization reaction of photochemical isomers.

FIG. 1 is an example of a photoisomeric organic material, and shows chemical structure changes of the organic material during a ring-closing reaction and a ring-opening reaction according to wavelength.
2 is an example of an upconversion nanoparticle, which is a conceptual diagram showing its optical properties.
3 is a schematic diagram schematically showing an upconversion plasmonic structure according to an aspect of the present invention.
4 is a schematic diagram schematically showing that the upconversion plasmonic structure of FIG. 3 is formed on a substrate.
5 briefly illustrates a method for manufacturing an upconversion plasmonic structure according to an aspect of the present invention.
Figure 6 is an image obtained through a scanning electron microscope (Scanning Electron Microscope) of the metal nanostructure formed when the rotation angle is changed according to the upconversion plasmonic structure manufacturing method of the present invention.
7 is a schematic diagram briefly showing the structure of a photochemical switching device according to an embodiment of the present invention, and a photograph taken through transmission electron microscopy of upconversion nanoparticles included in an insulating layer.
8 is a schematic diagram schematically showing a photochemical switching device according to an aspect of the present invention.
9 illustrates changes in photochemical properties of a photoisomeric organic material through a photochemical switching device according to an embodiment of the present invention.
10 is a schematic view of an example (MIM 10°) in which a quasi-periodic metal nanostructure is introduced and comparative examples according to an embodiment of the present invention.
11 is a comparison result of emission intensities of Comparative Example and Example under a near-infrared incident condition (a) of strong intensity (588 W/cm ² ) and a near-infrared incident condition (b) of weak intensity (31 W/cm ² ).
12 is a result of comparing the absorbance at the excitation wavelength of the upconverted nanoparticles included in Comparative Examples and Examples.
13 is a finite-difference time domain (FDTD) calculation result for electric field distribution at the excitation wavelength and the maximum emission wavelength of the embodiment.
14 is a result of comparing relative electric field amplification intensities at main emission wavelengths of Comparative Examples and Examples.
15 is a schematic diagram of the reversible photoisomerization reaction implemented in the present invention and a photo taken using a Complementary metal-oxide-semiconductor (CMOS) camera for the degree of emission according to the intensity of near-infrared rays having a wavelength of 980 nm.
16 is a photograph of the actual color change of 2-DTE and the result of measuring the absorbance change according to the photoisomerization reaction induced by near-infrared irradiation with a UV-Vis-NIR spectrometer.
17 shows measured values for changes in luminescence characteristics according to the ring closure reaction of Example.
18 is a quantitative and macroscopic view of the emission intensity according to whether quasi-periodic metal nanostructures are introduced or not.
19 is a result of measuring a change in absorbance of a reversible optically isomeric organic compound controlled according to a change in near-infrared irradiation conditions in an actual time domain.
20 is a result of measuring a change in emission intensity at a maximum emission wavelength according to a change in near-infrared irradiation conditions.
21 is a schematic diagram showing a device for measuring an optical image of a sample,
22 is a result showing the reversible optical isomerism characteristics according to the intensity and time of near-infrared ray irradiation as an optical image taken through a CMOS camera.
23 shows the evaluation of the stability of light absorption (a) and light emission (b) characteristics, respectively, by repeating the reversible photoisomerization reaction.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Prior to this, the terms or words used in this specification and claims should not be construed as being limited to the usual or dictionary meaning, and the inventor appropriately uses the concept of the term in order to explain his/her invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are only one of the most preferred embodiments of the present invention, and do not represent all of the technical ideas of the present invention, so at the time of this application, they can be replaced. It should be understood that there may be many equivalents and variations.

Electromagnetic field localization and surface plasmon resonance induced in metal nanostructures can enhance the optical properties of upconversion nanoparticles. In particular, the Metal-Insulator-Metal (MIM) configuration induces strong electric-field confinement in the insulator due to the formation of a gap plasmon resonance mode, which leads to upconversion nano By designing to match the excitation/emission region of the particle, the upconversion emission characteristics can be dramatically improved.

In order to implement reversible photoisomerization, resonance mode activation is required in a broadband wavelength that includes both ultraviolet and visible light regions substantially necessary for photoisomerization, and the upconversion plasmonic structure according to one aspect of the present invention It is a structure that induces broadband upconversion luminescence amplification by using quasi-periodic metal nanostructures manufactured by finely adjusting periodic nanostructures.

3 is a schematic diagram schematically showing an upconversion plasmonic structure according to an aspect of the present invention.

Referring to FIG. 3 , the upconversion plasmonic structure according to one aspect of the present invention includes a metal film layer 20, an insulating layer 30 formed on the metal film layer 20, and a semi-formed insulating layer 30. A quasi-periodic metal nanostructure 40 is included, and the insulating layer 30 includes upconverting nanoparticles 31 therein.

In addition, the nanometal body 41 constituting the quasi-periodic metal nanostructure 40 preferably has a maximum length of 2,000 nm or less, which is smaller than the infrared wavelength, so that plasmon resonance is possible. For example, the diameter of the nano metal body 41 is 200 nm. And, the height may be 10 to 1,000 nm.

At this time, upconverting nanoparticles (UCNPs) are excited by near-infrared rays and may be used that have the property of emitting visible and ultraviolet rays, for example (NaYF ₄ :Yb ³⁺ ,Er ³⁺ ), ( NaYF ₄ :Yb ³⁺ ,Tm ³⁺ ), (NaGdF ₄ :Yb ³⁺ ,Er ³⁺ ), (NaYF ₄ :Yb ³⁺ ,Er ³⁺ /NaGdF ₄ ) and (NaGdF ₄ :Yb ³⁺ ,Er ³⁺ /NaGdF ₄ ) may be used, and FIG. 2 shows NaYF ₄ :Yb ³⁺ ,Er ³ as an example of upconversion nanoparticles (UCNPs) as a core and NaYF ₄ :Yb as a shell. It shows the nanoparticles used as ³⁺ and Tm ³⁺ .

The upconversion plasmonic structure according to one aspect of the present invention induces a gap plasmon resonance mode in a Metal-Insulator-Metal (MIM) structure, and at this time, a quasi-periodic metal in the MIM structure It is a configuration in which the resonance effect of the MIM configuration is optimized for the excitation/emission region of the upconversion nanoparticles by introducing a nanostructure and upconverting nanoparticles in an insulator together.

4 is a schematic diagram schematically showing that an upconversion plasmonic structure according to an aspect of the present invention is formed on a substrate 10, and the substrate 10 may use, for example, silicon dioxide (SiO ₂ ), but the type is not particularly limited to

In the case of introducing a periodic metal nanostructure, there is a problem that the resonance region of the gap plasmon resonance mode is limited to the near-infrared region or the visible ray region, but the quasi-periodic metal nanostructure 40 of the present invention has a resonance region of the plasmon resonance mode It can be extended to the ultraviolet region that can be used as a photochemical reaction medium for organic compounds.

The quasi-periodic metal nanostructure 40 may be formed by transferring the periodic metal nanostructure on the insulating layer twice so as not to coincide with each other. The quasi-periodic metal nanostructure 40 may be formed by transferring at an angle twice, and as a transfer method, for example, a metal contact transfer method may be used.

5 schematically illustrates an embodiment of forming a quasi-periodic metal nanostructure. Referring to FIG. 5, after primary transfer (c) of the periodic metal nanostructure on the insulating layer 30 including the upconversion nanoparticles, the primary transferred periodic metal nanostructure coincides with the primary transfer material. A quasi-periodic metal nanostructure (f) may be formed by secondary transfer (e) of the periodic metal nanostructure at a rotation angle (d) that does not occur.

The periodic metal nanostructure forming the quasi-periodic metal nanostructure 40 may preferably have the same structure used for primary transfer and secondary transfer in terms of productivity, but different structures may be used. It is only necessary that the primary transcript and the secondary transcript do not coincide with each other.

As an example of forming the quasi-periodic metal nanostructure 40, the periodic metal nanostructure may be in a hexagonal array. In the case of a hexagonal array, it may be preferable in terms of easily forming various quasi-periodic metal nanostructures by adjusting the rotation angle.

6 shows a periodic metal nanostructure in a hexagonal array on an insulator by a metal contact transfer method, and secondary transfer is performed on a transfer body once transferred to the primary transfer body at 10° (a) and 20°, respectively. (b), with a difference in rotation angle of 30° (c), the periodic metal nanostructure of the same hexagonal array as the primary transfer was transferred, and the secondary transferred material was scanned using a scanning electron microscope (Scanning Electron Microscope). This is a picture taken through Electron Microscopy (SEM).

When the quasi-periodic metal nanostructure 40 is introduced, the emission yield is all improved compared to the case where the periodic metal nanostructure formed only by primary transfer is introduced. In particular, when the periodic metal nanostructure is in a hexagonal array , The rotation angle of the primary transfer member formed through the primary transfer and the secondary transfer member formed through the secondary transfer may be 5 ° to 40 °, particularly when the rotation angle is 5 ° to 15 °, the insulating layer (30 ), the excitation wavelength absorbance of the upconverted nanoparticles 31 and the luminescence intensity under near-infrared incident conditions are particularly excellent.

In the upconversion plasmonic structure according to one aspect of the present invention, the insulating layer 30 located between the metal film layer 20 and the quasi-periodic metal nanostructure 40 is such that the upconversion nanoparticles 31 form the metal 20 or 41), it is necessary to prevent the problem of extinction of fluorescence upon contact, but the thinner the better, the better the gap plasmon resonance mode through the MIM configuration is expressed. From this, the thickness of the insulating layer 30 is 1 nm to 1 can be formed in μm. When the thickness of the insulating layer is less than 1 nm, the upconversion nanoparticles are exposed to the outside of the insulator due to the excessively thin thickness, and the insulation effect may deteriorate. This widens, and a problem in which the gap plasmon resonance effect is reduced may occur.

The insulating layer 30 includes upconverted nanoparticles 31 therein, and the interaction between the metal film layer 20, the insulating layer 30, the upconverted nanoparticles 31 and the quasi-periodic metal nanostructures 40 Through this action, surface/gap plasmon resonance is generated, and the generated surface/gap plasmon resonance forms a broadband resonance mode from the near infrared region to the ultraviolet region. At this time, in order to generate surface/gap plasmon resonance more effectively, it is preferable that the upconversion nanoparticles 31 included in the insulating layer 30 are formed as a monolayer.

7 schematically shows the structure of a photochemical switching device in which a DTE film is formed on quasi-periodic metal (silver) nanostructures as an embodiment of the present invention. Together, it shows a picture taken with a transmission electron microscope (TEM) of the upconversion nanoparticles formed as a monolayer inside the insulator.

The metal film layer 20 and the quasi-periodic metal nanostructure 40 are not particularly limited as long as they are metal capable of forming a gap plasmon resonance mode to form the MIM structure, and the metal film layer 20 and the quasi-periodic metal nanostructure ( 40) may have the same type of metal, but may be different. For example, the metal film layer 20 and the quasi-periodic metal nanostructure 40 may each be gold, silver, aluminum, copper, platinum, or an alloy thereof, and as an embodiment of the present invention, FIGS. 5 to 6 As described above, both the metal film layer 20 and the quasi-periodic metal nanostructure 40 may use silver (Ag).

Since the upconversion plasmonic structure according to one aspect of the present invention can emit ultraviolet light capable of controlling the photoisomerization reaction of photoisomeric organic matter, a photochemical switching device according to another aspect of the present invention using this It is characterized in that it comprises the up-conversion plasmonic structure and a photo-isomeric organic material layer.

The photoisomeric organic material means a material whose chemical structure is changed by the wavelength of irradiated light. For example, the material shown in FIG. 1 can be used, and the photoisomeric material in FIG. and reacts with visible light to close the ring. Therefore, in the photochemical switching device according to one aspect of the present invention, the upconversion nanoparticles 31 included in the insulating layer 30 absorb near-infrared rays, and the upconversion nanoparticles 31 according to the intensity of the absorbed near-infrared rays The wavelength of the emitted light is changed to visible light or ultraviolet light, and through the MIM structure composed of the metal film layer 20, the insulating layer 30, and the quasi-periodic metal nanostructure 40, Light emitted from is amplified by plasmon resonance and can reversibly change the chemical structure of the photoisomeric organic material layer.

The photoisomeric organic material may use, for example, at least one of a fulgide-based compound, a diarylethene-based compound, an azobenzene-based compound, and a spiropyran-based compound. For example, 2,3-Bis(2-methyl-6-phenyl-1,1-dioxobenzo[b]thiophen-3-yl)thiophene as a diarylethene, or 2,3-Bis(2-ethyl-6- Phenyl-1,1-dioxobenzo[b]thiophen-3-yl)thiophene may be used, but is not limited to the above examples and examples, and any photoisomeric organic material may be used without particular limitation. The thickness of the photoisomeric organic material layer is preferably 10 nm to 1,000 nm in consideration of the plasmonic resonance effect.

7 to 8 show an embodiment of a structure of a photochemical switching device according to an aspect of the present invention. Referring to FIG. 8 , the photochemical switching device includes an insulating layer 30 including upconversion nanoparticles 31 formed on the metal film layer 20 therein, and a quasi-periodic metal nanostructure formed on the insulating layer 30. (40) and a photoisomeric organic material layer (50) formed on the quasi-periodic metal nanostructure (40). As an embodiment of the photochemical device of the present invention, a substrate may be positioned below the metal film layer 20, and the substrate may be used to easily form the metal film layer, for example, silicon dioxide (SiO ₂ ) can be formed

9 is a graph showing the change in photochemical properties of a photoisomeric organic material through a photochemical switching device according to an embodiment of the present invention, and a graph of absorbance according to wavelength when near-infrared rays of strong intensity are irradiated (a) and near-infrared rays of weak intensity It shows that there is a difference in the absorbance graph (b) according to the wavelength when irradiated. Since the absorbance pattern according to the wavelength changes according to the structure of the photoisomeric organic material, referring to FIG. indicates that it can be changed. Using these characteristics, the photochemical switching device according to one aspect of the present invention may be included and used in a non-volatile optical memory device, a fluorescence microscope, or a transistor. The fluorescence microscope may specifically be a super-resolution fluorescence microscope, and the transistor may be a light-based transistor.

The method for manufacturing an upconversion plasmonic structure according to another aspect of the present invention is characterized in that it essentially includes the following 5 steps, specifically (S1) an insulating layer containing upconversion nanoparticles on a metal film layer Laminating step, (S2) primary vacuum deposition of a metal thin film on the transfer frame on which protrusions are periodically formed at a constant height on the base portion, (S3) the metal deposited on the protrusions of the transfer frame formed in step S2. Forming a periodic metal nanostructure by first transferring a thin film onto the insulating layer, (S4) vacuum depositing a second metal thin film on the transfer frame, and (S5) protruding parts of the transfer frame formed in the step S4. and forming a quasi-periodic metal nanostructure by rotating the metal thin film deposited thereon so as not to coincide with the first transfer and performing secondary transfer on top of the periodic stack formed in the step S3.

The manufacturing method of the present invention finely adjusts the rotation angle of a fixed periodic metal nanostructure and forms various quasi-periodic metal nanostructures on an insulating layer containing a light emitting body through sequential metal-contact transfer. It has the advantage of being able to manufacture efficiently and effectively.

FIG. 5 briefly illustrates a method for manufacturing an upconversion plasmonic structure according to an aspect of the present invention, and each step will be described in detail with reference to FIG. 5 .

Step (S1)

Referring to a of FIG. 5 , a stacked structure is first formed by stacking an insulating layer including upconversion nanoparticles 30 therein on the metal film layer 20 . At this time, in order to facilitate the formation of the metal film layer 20, the substrate 10 may be located under the metal film layer 20, and the type of substrate is preferably an insulator, for example, silicon dioxide (SiO ₂ ) can be used.

Step (S2)

Referring to b of FIG. 5 , a metal thin film is first vacuum deposited on the transfer frame 42 having periodically formed protrusions at a constant height on the base portion. The metal thin film to be deposited is not particularly limited as long as it is a metal capable of plasmon resonance, and silver (Ag) can be used, for example.

The protrusions on the transfer frame 42 are formed periodically, for example, may be formed periodically in a hexagonal array.

When the metal thin film is deposited on the transfer frame, the protruding portion of the transfer frame 42 serves to show discontinuity between the metal thin film deposited at a high point and the metal thin film deposited at a low point. In addition, it is preferable that the protruding part has a constant height and the high point is flat so that metal transfer through the transfer frame 42 is easy. The protruding portion may have, for example, a cylindrical shape, but the shape is not particularly limited, and the transferred metal nanostructure must be formed small to enable plasmon resonance, and specifically, it is preferably 2,000 nm or less, which is smaller than the infrared wavelength.

Step (S3)

Referring to FIG. 5(c), the upper surface of the transfer frame, which is firstly vacuum-deposited in step S2, is firstly transferred on top of the insulating layer formed in step S1. At this time, the transfer may be performed using a metal contact transfer method, and through the transfer, only the metal deposited on the protrusion, which is the high point of the transfer frame, is transferred to the upper portion of the insulating layer, thereby forming a periodic metal nanostructure on the upper portion of the insulating layer.

Steps (S4) and (S5)

Referring to d and e of FIG. 5 , steps S4 and S5 repeat steps S2 and S3, but the periodic metal nanostructure is transferred by adjusting the rotation angle so that it does not coincide with the periodic metal nanostructure transferred in step S3. There is a difference in the secondary transfer on the laminated body.

At this time, when the protrusions as the transfer frame 42 are formed in a hexagonal array, the rotation angle between the primary transfer of step S3 and the secondary transfer of step S5 is not particularly limited, but is 5 ° to 40 ° Secondary transfer can be performed so that there is a rotation angle difference, and plasmonic resonance can occur more effectively when the rotation angle difference is between 5° and 15°, for example, when the rotation angle difference is 10° as an embodiment of the present invention. Excellent plasmonic resonance was observed when

The primary transfer of step S3 and the secondary transfer of step S5 can proceed in the same way except for the difference in rotation angle, but the primary transfer of step S3 is directly transferred onto the insulating layer, and the secondary transfer of step S5 is additionally transferred on top of the periodic metal nanostructure on which the primary transfer has already proceeded, and the primary transfer in step S3 proceeds with a soft baking process, and the secondary transfer in step S5 proceeds with a hard baking process in terms of process efficiency. desirable.

In the soft baking process of step S3, in detail, the upper surface of the transfer frame on which the metal is deposited on the upper surface may be subjected to metal contact transfer at a temperature of 50 to 100 ° C. for 5 to 30 minutes on the upper surface of the insulating layer. In the baking process, after setting the rotation angle to transfer the upper surface of the transfer frame on which the metal is deposited to the upper surface of the insulating layer on which the periodic metal nanostructure is formed, metal contact type transfer is performed at a temperature of 120 to 170 ° C. for 50 to 70 minutes. can

A method for manufacturing a photochemical switching device according to another aspect of the present invention may further include stacking a photoisomeric organic material layer on top of the quasi-periodic metal nanostructure after step 5 of the method for manufacturing the upconversion plasmonic structure. can The photoisomeric organic material may use, for example, at least one of a fulgide-based compound, a diarylethene-based compound, an azobenzene-based compound, and a spiropyran-based compound. The stacking of heterogeneous organic materials may be carried out by, for example, direct spin coating, nozzle coating, drop casting, etc. of organic materials, and depending on the function, other materials (eg, SiO ₂ sol-gel, TiO ₂ sol-gel, etc.) may be mixed and stacked for use.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in many different forms and is not limited to the manufacturing examples and examples described herein.

[Preparation Example: Preparation of Upconversion Plasmonic Structure]

Perfluoropolyether (PFPE), an ultraviolet curing material, was dropped on a polyurethane acrylate (PUA) master on which a hole pattern with a constant diameter of 200 nm was periodically etched and engraved, and then a polyethylene terephthalate (PET) film was placed and nitrogen supply and pressure were applied. PFPE is cured by exposing to a UVA environment for 15 minutes while adding.

After the curing of PFPE is complete, if you carefully separate it from the PUA master, a cylindrical PFPE transfer frame is completed. The PFPE transfer frame used in the production example of the present invention has a base portion of about 50 mm x 50 mm in size, a cylinder with a diameter of 200 nm, a height of 200 nm, and a hexagonal array with a distance of 400 nm between the centers of the cylinders. I have it.

By vacuum depositing a much thinner metal thin film (35 nm) than the height (200 nm) of the fabricated PFPE transfer frame, a structure without metal connection at the high and low points of the nanostructure can be obtained.

First, after aligning the PFPE transfer frame on which the metal nanostructure to be transferred is deposited on the insulator thin film on the alignment mask, it is transferred by performing a soft baking process at about 80 ° C for 15 to 20 minutes (first transfer). Thereafter, by setting the rotation angle difference between the first transfer and the second transfer to 10°, the second metal nanostructure to be transferred is aligned, and then a quasi-periodic metal nanostructure is formed through a hard baking process at 140° C. for 1 hour. do.

In the present invention, upconverted nanoparticles are mixed with Perhydropolysilazane (PHPS), which is a SiO ₂ sol-gel, and toluene at a ratio of 2.85 wt%, and then spin for 60 seconds at a speed of 3000 rpm on a substrate on which silver (Ag) metal is deposited It was formed by spin casting.

The metal substrate was fabricated by depositing a 100 nm silver film on the cleaned substrate at 1 x 10 ^-5 torr using a thermal evaporator.

[Experimental Example 1: Confirmation of Broadband Resonance Effect of Upconversion Plasmonic Structure]

The upconversion plasmonic structure prepared in Preparation Example 1 (Example, MIM 10 °) was irradiated with near-infrared rays by varying the intensity of light, and the upconversion plasmonic structure of the present invention was used to excite the upconversion nanoparticles at 980 nm. In addition to an increase in absorption in the region, a rapid increase was observed in all light emitting regions, and the results are shown in FIGS. 10 to 14 .

10 to 14 are results of measuring and calculating the optical properties of improved upconversion nanoparticles through the introduction of the upconversion plasmonic structure of the present invention. It is a schematic diagram for 10 ° (Example 1), Ref (Comparative Example 1), MI single (Comparative Example 2), IM (Comparative Example 3), and MIM single (Comparative Example 4).

(Experimental Example 1-1: Comparison of emission according to near-infrared incident conditions)

Figure 11a is a result of comparing the luminous intensity of Comparative Example and Example under near-infrared ray incident conditions of strong intensity (588 W/cm ² ), when compared to Comparative Examples in the case of Example at each main emission wavelength, up to 130 (346 nm), 223 (452 nm), 436 (544 nm), and 502 (657 nm) fold amplification of luminescence was achieved. In addition, b of FIG. 11 is a result of comparing the luminous intensity of the comparative example and the example under the near-infrared light incident condition of weak intensity (31W/cm ² ), and in the case of the example, compared to the comparative examples, up to 200 ( 544 nm) and 257 (657 nm) times.

(Experimental Example 1-2: Comparison of absorbance according to structure)

Figure 12 is a comparison of the absorbance at the excitation wavelength of upconversion nanoparticles included in Comparative Examples and Examples, which is the basis for the steady-state view of the luminescence amplification phenomenon of the Examples. For clear comparison, the relative absorbance intensity obtained by dividing the absorbance of Example (MIM 10°) and Comparative Examples 2 to 4 (MI single, IM, MIM single) by the absorbance of Comparative Example 1 (Ref) is shown. Specifically, Example 1 (MIM 10 °) at the corresponding wavelength (980 nm) exhibited absorbance amplified about 55 times compared to Comparative Example 1 (Ref), and absorbance amplified about 11 times than Comparative Example 4 (MIM single) showed

(Experimental Example 1-3: Comparison of finite difference time zone according to electric field distribution)

13 is a finite-difference time domain (FDTD) calculation result for the electric field distribution at the excitation wavelength and maximum emission wavelength of Example 1, which provides a theoretical basis for absorbance amplification and formation of a resonance mode. . The electromagnetic field distribution at the excitation wavelength showed a localized surface plasmon resonance phenomenon that was strongly focused around the silver nanostructure (Example 1), and the electric field distribution at the maximum emission wavelength was in the form of a gap plasmon resonance mode. was induced by

(Experimental Example 1-4: Comparison of electric field amplification intensity according to emission wavelength)

14 is a result of comparing relative electric field amplification intensities at main emission wavelengths of Comparative Examples and Examples. The corresponding numerical value is a value obtained by dividing the electromagnetic field strength at each emission wavelength derived from the three-dimensional finite-order time domain calculation by the calculation result of Comparative Example 3 (IM). At this time, in Comparative Example 1 (Ref), electromagnetic field amplification did not appear (converge to 0), so it was not displayed. Referring to FIG. It can be confirmed that the amplification is greater than that of (MIM single). The relative value of the electromagnetic field intensity at each emission wavelength shows the same tendency as the emission intensity amplification trend obtained through measurement, which is an important theoretical basis for the emission amplification phenomenon along with the induction of the absorption resonance mode.

[Experimental Example 2: Reversible Photoisomerization Reaction Experiment of Photochemical Switching Device]

For demonstration of the photochemical switching device according to the present invention as a photochemical switching medium, 2,3-Bis(2-methyl-6- phenyl-1,1-dioxobenzo[b]thiophen-3-yl)thiophene(1), and 2,3-Bis(2-ethyl-6-phenyl-1,1-dioxobenzo[b]thiophen-3-yl) A photoisomeric organic layer of thiophene(2) was introduced. Photochemical switching device (Example 1 -1) was prepared, and 2,3-Bis (2-ethyl-6-phenyl-1,1-dioxobenzo[b]thiophen-3-yl)thiophene was introduced into the organic layer in Example 1 to form a photochemical switching device (practice Example 1-2) was prepared. Referring to FIG. 1, the photoisomeric organic material absorbs the amplified emission of light in the ultraviolet region under high-intensity near-infrared irradiation conditions and causes a ring closure reaction, and absorbs the amplified visible light emission under low-intensity near-infrared irradiation conditions. An opening reaction occurs.

In Experimental Example 2, whether or not the reversible photoisomerization reaction is efficiently controlled through the photoswitching upconversion characteristics of the photochemical switching device (Example 1-2, Example 1-2) of the present invention was determined by luminescence imaging and optical properties It was verified through change measurement.

15 to 20 show the results of measuring the optical properties of photo-isomeric organic compound resonance structures (Examples 1-1 and 1-2) to which the quasi-periodic plasmonic structure (Example 1) is applied. This is a schematic diagram of the reversible photoisomerization reaction implemented in the invention and the degree of emission of Example 1-1 according to the intensity of near-infrared rays having a wavelength of 980 nm using a complementary metal-oxide-semiconductor (CMOS) camera.

(Experimental Example 2-1: Comparison of absorbance according to photoisomerization reaction)

Figure 16 is a result of measuring the absorbance change according to the photoisomerization reaction induced by near-infrared irradiation with a UV-Vis-NIR spectrometer and a photograph of the actual color change of 2-DTE (upper left, 2o: before color change, 2c: after color change). The two DTE thin films (Example 1-1 and Example 1-2) used in the present invention showed a decrease in absorbance in the UV region below 300 nm and an increase in absorbance in the range of about 500 nm as the ring closure reaction progressed.

(Experimental Example 2-2: Comparison of luminescence intensity according to photoisomerization reaction)

FIG. 17 is a measurement value of the change in light emitting characteristics of Example 1-1 and Example 1-2, and it can be confirmed that the light emitting characteristic of the DTE thin film is developed as the ring closure reaction proceeds under the near-infrared irradiation condition.

(Experimental Example 2-3: Comparison of luminescence intensity according to introduction of quasi-periodic structure)

18 is a result of quantitatively and macroscopically illustrating the emission intensity according to whether a quasi-periodic metal nanostructure is introduced or not, and two DTE thin films (implemented Example 1-1 (Methyl) and Example 1-2 (Ethyl)) both show luminescence intensity amplification approaching about 10 times. The corresponding DTE luminescence amplification was captured through a CMOS camera.

(Experimental Example 2-4: Comparison of absorbance of optical isomeric organic compounds according to near-infrared irradiation)

19 is a result of measuring a change in absorbance of a reversible optically isomeric organic compound controlled according to a change in near-infrared irradiation conditions in an actual time domain. The measurement was shown based on the maximum absorption wavelength in the visible light region of the ring-closed structure of each DTE. Specifically, in the case of the DTE structure introducing the quasi-periodic metal nanostructure (1 PMIM10°, 2 PMIM10°), it takes about 10 seconds to reach the maximum absorbance under high-intensity near-infrared irradiation conditions, whereas in Comparative Example In the case of introducing the DTE thin film (1 PRef, 2 PRef), it took about 30 seconds. Similarly, when the corresponding structures were irradiated with weak intensity near-infrared rays, the absorbance of the quasi-periodic nanostructures (1 PMIM10°, 2 PMIM10°) converged to 0 after about 28 seconds, whereas the comparative examples (1 PRef, 2 PRef) In this case, the ring opening reaction was terminated after about 60 seconds.

(Experimental Example 2-5: Comparison of luminescence characteristics of optical isomeric organic compounds according to near-infrared irradiation)

20 is a result of measuring a change in emission intensity at a maximum emission wavelength according to a change in near-infrared irradiation conditions. In the high-intensity near-infrared irradiation condition and the weak-intensity near-infrared irradiation condition, a similar trend to Experimental Example 2-4 was shown.

[Experimental Example 3: Optical Image Measurement of Photochemical Switch Device]

21 to 23 are results of measuring an optical image of an actual sample using a photochemical switching device according to an embodiment of the present invention, and FIG. 21 is a schematic diagram showing a device for measuring an optical image of a sample,

(Experimental Example 3-1: Observation of reversible optical heterogeneity characteristics according to near-infrared irradiation intensity and time)

22 shows optical images of reversible optical isomerism according to the intensity and time of near-infrared ray irradiation, and was taken through a CMOS camera. A specific pattern was introduced to demonstrate the applicability of the present invention as a fluorescence imaging template, and through the results of FIG. 22, the time difference photoconversion process and luminescence amplification suggest that the structure proposed in the present invention can be used as a significant luminescence amplification medium. suggests

(Experimental Example 3-2: Evaluation of stability of luminous properties)

23 shows the evaluation of the stability of light absorption (a) and light emission (b) characteristics, respectively, by repeating the reversible photoisomerization reaction. In the case of DTE molecules, it is widely known that the photoisomerization reaction is controlled using an external light source in the ultraviolet and visible light regions having relatively strong energy, so that the photoisomerization reaction easily loses its properties as the photoisomerization reaction is repeated. there is. In the case of the quasi-periodic nanostructure proposed in the present invention, since an external light source in the near-infrared region, which has little effect on DTE molecules, is used, about 95% or more of the existing optical properties are maintained in reversibility evaluations of about 20 times or more.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible without departing from the technical spirit of the present invention described in the claims. It will be obvious to those skilled in the art.

10: materials
20: metal film layer
30: insulating layer
31: upconversion nanoparticles
40: quasi-periodic metal nanostructure
41: nano metal body

Claims (18)

a metal film layer;
an insulating layer formed on the metal film layer; and
A quasi-periodic metal nanostructure formed on the insulating layer;
The insulating layer includes upconverting nanoparticles therein, upconverting plasmonic structure.
According to claim 1,
The quasi-periodic metal nanostructure is formed by transferring the periodic metal nanostructure on the insulating layer twice at different rotation angles.
According to claim 2,
The periodic metal nanostructure is a metal nanostructure of a hexagonal array, an upconversion plasmonic structure.
According to claim 3,
The quasi-periodic metal nanostructure is formed by transferring the metal nanostructure of the hexagonal array twice with a rotation angle difference of 5 ° to 40 °, upconversion plasmonic structure.
According to claim 1,
The insulating layer has a thickness of 1 nm to 1 μm, upconversion plasmonic structure.
According to claim 1,
The upconversion nanoparticles included in the insulating layer are formed as a monolayer, upconversion plasmonic structure.
According to claim 1,
The metal film layer and the quasi-periodic metal nanostructure are each made of one member selected from the group consisting of gold, silver, aluminum, copper, platinum, and alloys thereof.
Claims 1 to 7 of any one of the up-conversion plasmonic structure; and
A photochemical switching device comprising a photoisomeric organic material layer.
According to claim 8,
The photo-isomeric organic material layer is formed on the quasi-periodic metal nanostructure of the up-conversion plasmonic structure, photochemical switching element.
A non-volatile optical memory device comprising the photochemical switching device of claim 8.
A fluorescence microscope comprising the photochemical switching element of claim 8.
A transistor comprising the photochemical switching element of claim 8 .
(S1) stacking an insulating layer containing upconversion nanoparticles on the metal film layer;
(S2) firstly vacuum-depositing a metal thin film on the transfer frame on which protrusions are periodically formed at a constant height on the base portion;
(S3) forming a periodic metal nanostructure by firstly transferring the metal thin film deposited on the protruding portion of the transfer frame formed in step S2 to an upper portion of the insulating layer;
(S4) secondary vacuum deposition of a metal thin film on the transfer frame; and
(S5) The metal thin film deposited on the protrusion of the transfer frame formed in step S4 is rotated so as not to coincide with the first transfer, and the second transfer is performed on the upper part of the periodic stack formed in step S3 to form a quasi-periodic metal nanostructure. doing;
Upconversion plasmonic structure manufacturing method comprising a.
According to claim 13,
The transfer frame is an upconversion plasmonic structure manufacturing method in which protrusions of a certain height are periodically formed on the base portion in the form of a hexagonal array.
According to claim 14,
The secondary transfer of the step S5 has a rotation angle difference of 5 ° to 40 ° from the primary transfer of the step S3, upconversion plasmonic structure manufacturing method.
According to claim 14,
The transfer frame is a method of manufacturing an upconversion plasmonic structure in which a protrusion of a certain height on the base portion has a cylindrical shape.
According to claim 13,
The primary transfer of step S3 proceeds to a soft baking process,
The secondary transfer of step S5 proceeds to a hard baking process, an upconversion plasmonic structure manufacturing method.
(S1) depositing an insulating layer containing upconversion nanoparticles on the metal substrate layer;
(S2) firstly vacuum-depositing a metal thin film on the transfer frame on which protrusions are periodically formed at a constant height on the base portion;
(S3) forming a periodic metal nanostructure by firstly transferring the metal thin film deposited on the protruding portion of the transfer frame formed in step S2 to an upper portion of the insulating layer;
(S4) secondary vacuum deposition of a metal thin film on the transfer frame;
(S5) The metal thin film deposited on the protrusion of the transfer frame formed in step S4 is rotated so as not to coincide with the first transfer, and the second transfer is performed on the upper part of the periodic stack formed in step S3 to form a quasi-periodic metal nanostructure. doing; and
(S6) stacking a photo-isomeric organic material layer on top of the quasi-periodic metal nanostructure;
Photochemical switching device manufacturing method comprising a.

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