A non-close-packed noble metal nanoparticle ordered lattice and preparation method thereof

Abstract

The present invention belongs to the technical field of micro-nano optical material preparation, and specifically relates to a non-close-packed noble metal nanoparticle ordered lattice and a preparation method thereof. The method firstly uniformly applies a layer of ultraviolet curing optical adhesive on the surface of a flat substrate, uses an embossing template with uniform grooves to emboss a micro-nano quasi-continuous film structure, then deposits a layer of noble metal film, and finally obtains a non-close-packed noble metal nanoparticle ordered lattice by annealing and calcining. The noble metal nanoparticles are spherical in morphology, have uniform particle size, adjustable particle size and period, and are highly ordered, and can be stored for a long time under room temperature and ambient atmosphere conditions. The preparation technology is fast, simple, economical and efficient, and is particularly suitable for large-area (>4 inches) and low-cost preparation of non-close-packed noble metal nanoparticle ordered lattices, and is suitable for industrial large-scale production applications.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nano optical material preparation, and specifically relates to an ordered lattice of non-close-packed noble metal nanoparticles and an etching-free, low-cost, batch preparation method thereof. Background Art

[0002] Non-close-packed ordered lattices arranged according to certain rules based on nanoscale material structural units are of great significance in the fields of optoelectronic devices and advanced manufacturing. In particular, non-close-packed ordered lattices composed of precious metal (Au, Ag, etc.) nanounits can not only produce localized surface plasmon resonance (LSPR) under light field excitation, but also produce a new plasmon surface lattice resonance coupling (SLR) and other effects, which are widely used in optical sensing, surface enhanced Raman scattering (SERS), optoelectronic devices, photocatalysis and other fields. Therefore, the high-quality preparation of precious metal non-close-packed ordered lattices is not only the key material basis for studying its new optical properties, but also has important significance for its practical application and promotion.

[0003] At present, the main preparation methods of precious metal nanostructure non-close-packed lattices are: shadow mask imprint template method and colloidal crystal in-situ calcination method. The principle of the traditional shadow mask imprint template method is: using a hollow structure array as a mask, combined with magnetron sputtering deposition, directly depositing metal on a flat substrate, and removing the mask to obtain a high-quality non-close-packed structure array. This method has the advantages of controllable array structure, precise cycle control, and high-quality and easy repeatability. However, the acquisition of the mask imprint template depends on some complex etching processes (such as photolithography, electron beam etching, reactive ion etching, etc.), the preparation process is complicated, and the mask is difficult to recycle, etc., which greatly limits its promotion and use. In addition, during the array preparation process, most of the precious metals are deposited on the mask plate, and its actual utilization rate is less than 20%, resulting in a serious waste of scarce resources; and due to the limitations of etching processes and equipment, its production cost is expensive and the efficiency is not high. In contrast, the colloidal crystal in-situ calcination strategy is an emerging preparation technology that uses colloidal crystals assembled from polystyrene (PS) microspheres as an imprint template, combined with magnetron sputtering metal deposition, to form a large-area non-close-packed ordered lattice structure after in-situ calcination. This emerging method exhibits the advantages of low cost, high efficiency, and near-zero-loss utilization of precious metals. The array period can be controlled by changing the size of the PS microspheres. Obviously, this method has achieved an effective alternative to the traditional shadow mask imprint template method and has attracted much attention. However, the non-close-packed lattice structure prepared by this method is mainly determined by the self-assembly quality of the monolayer film of the colloidal crystal, which will inevitably result in poor array reproducibility and low reliability consistency, and cannot achieve reproducible batch preparation; this greatly limits the further promotion of this method in industrial batch preparation.

[0004] Therefore, developing a new, etching-free, low-cost, and efficient preparation method to batch prepare ordered lattices of non-densely packed precious metal nanoparticles with controllable cycle, size, shape, and composition is the only way for industrial mass production and has important scientific significance. Summary of the invention

[0005] In order to solve the shortcomings of the current preparation methods of non-close-packed ordered lattices, a preparation method of non-close-packed ordered lattices of noble metal nanoparticles is provided. The method is etching-free, low-cost, and batch-prepared.

[0006] To achieve the above object, the present invention adopts the following technical solution: a method for preparing an ordered lattice of non-close-packed noble metal nanoparticles, comprising the following steps:

[0007] S1, treating the flat substrate to obtain a clean and hydrophilic surface;

[0008] S2, evenly coating a layer of cured optical adhesive on the surface of the flat substrate treated as above, with a thickness of 2-100 μm;

[0009] S3, taking an imprint template, the surface of which is provided with non-penetrating, orderly dot-array grooves, covering the side provided with the grooves on the cured optical adhesive for imprinting, and then curing the cured optical adhesive to form a quasi-continuous film structure, and removing the imprint template;

[0010] S4, depositing a layer of noble metal film with a thickness of 2-50 nm on the surface of the cured optical adhesive forming the quasi-continuous film structure;

[0011] S5. Place the flat substrate with the deposited precious metal film into a muffle furnace for annealing and calcining at a temperature of 500-1500° C. for 0.5-10 h. After the calcination, cool the substrate naturally to obtain an ordered lattice of non-densely packed precious metal nanoparticles.

[0012] As a further improvement of the preparation method of ordered lattices of non-close-packed noble metal nanoparticles:

[0013] Preferably, the material of the flat wafer substrate in step S1 is silicon wafer, quartz or sapphire.

[0014] Preferably, the flat substrate in step S1 is cleaned by using a plasma cleaning machine. 2 Wash to obtain a clean and hydrophilic surface.

[0015] Preferably, the cured optical adhesive in step S2 is a UV-curable optical adhesive, which is cured under a UV lamp; or, the cured optical adhesive is a thermal-curable adhesive, which is cured under heating conditions.

[0016] Preferably, in step S2, the cured optical adhesive is coated on the surface of the flat substrate by spraying or spin coating, the spin coating speed is 1000-7000 r / min, and the spin coating time is 10-300 s.

[0017] Preferably, in step S3, the aspect ratio of the grooves on the imprint template is 0.2-2.0, and the distance between the centers of adjacent grooves is 200-5000 nm.

[0018] Preferably, in step S3, the shape of the grooves on the imprint template is hemispherical or pyramidal, and adjacent grooves are distributed in a tetragonal close-packed arrangement or a hexagonal close-packed arrangement.

[0019] Preferably, in step S4, a noble metal film is deposited on the surface of the UV-curable optical adhesive by a magnetron sputtering process, the current of the magnetron sputtering is 5-50 mA, and the sputtering time is 0.5-20 min.

[0020] Preferably, the method for preparing the imprint template in step S3 is as follows:

[0021] S11, adding polymer colloid microspheres to water, and assembling the polymer microsphere colloids on the water surface by a gas-liquid interface self-assembly method to obtain an ordered polymer colloid microsphere monolayer film;

[0022] S12. Based on the non-destructive transfer method, the polymer colloid microsphere monolayer film is transferred to a quartz substrate, and a layer of polydimethylsiloxane (PDMS) is poured on the polymer colloid microsphere monolayer film. It is placed in a vacuum drying oven until the gaps between adjacent polymer colloid microspheres are filled with PDMS, and then placed in an oven at 40 to 100°C for curing. The PDMS is then peeled off, and the result is an imprint template with non-penetrating ordered lattice grooves.

[0023] The second object of the present invention is to provide an ordered lattice of non-close-packed precious metal nanoparticles prepared by the above preparation method.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) The present invention provides a method for preparing an ordered lattice of non-close-packed precious metal nanoparticles, by using an embossing template with non-penetrating ordered lattice grooves on the surface, a micro-nano quasi-continuous film structure is embossed on a flat substrate coated with optical glue, and then a layer of precious metal film is deposited by magnetron sputtering, and finally annealed and calcined to obtain it. The micro-nano quasi-continuous film is produced by embossing the embossing template, the embossing template can be reused, and the operation method is fast and simple. Based on the Oswald ripening mechanism, the flat substrate after the precious metal film is deposited is placed in a high-temperature furnace for annealing and calcining. After the optical glue is decomposed and removed at high temperature, an ordered lattice of non-close-packed precious metal nanoparticles is obtained. The morphology of the precious metal nanoparticles is spherical, the particle size is uniform, and the size is adjustable within the range of 50 to 200 nm. It has good orderliness and stability and can be preserved for a long time at room temperature and ambient atmosphere.

[0026] 2) The preparation method is not only fast, simple, economical and efficient, but also has a conversion utilization rate of more than 90% for precious metals; the preparation process only requires some common equipment such as a plasma cleaner, a spin coater, a tablet press, and an ultraviolet lamp, with low equipment requirements, a simple process, and easy operation; the preparation method is particularly suitable for large-area, low-cost preparation of ordered lattices of non-densely packed precious metal nanoparticles, and is suitable for large-scale industrial production applications.

[0027] 3) The present invention also provides a method for preparing an imprint template, wherein polymer microsphere colloids are assembled on a water surface by a gas-liquid interface self-assembly method to obtain a two-dimensional large-area highly ordered colloidal crystal monolayer film; the monolayer film is then directly and non-destructively scooped out, transferred to a quartz substrate and dried;

[0028] After pouring PDMS precursor on the above-mentioned single-layer colloidal crystal, it is placed in a vacuum drying oven to remove excess bubbles. After heating and curing, the cured PDMS is peeled off from the flat substrate, and an "inverse opal" ordered array structure of the colloidal crystal is obtained on the flat substrate, and this flat substrate is used as an imprint template.

[0029] 4) The prepared hexagonal non-close-packed noble metal nanoparticle ordered lattice was tested by UV-Vis-NIR spectrophotometer. From the test results, it can be seen that the Au nanoparticle lattice has two characteristic absorption peaks at 520-540nm and 600-740nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution of the embodiment, the drawings required for use in the description of the embodiment will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 Schematic diagram of the process for preparing an ordered lattice of non-close-packed Au nanoparticles according to Example 1.

[0032] Figure 2 The scanning electron microscope photos shown in (a), (b), and (c) are respectively the hexagonal close-packed PDMS imprint template with a period of 500 nm used in step (3) of Example 1 of the present invention, the quasi-continuous optical adhesive hemispherical film obtained after photocuring of the imprint template, and the hexagonal non-close-packed Au nanoparticle ordered lattice obtained in step (5) of Example 1 of the present invention. Figure 2 (d) is an optical photograph of the hexagonal close-packed PDMS imprint template with a period of 500 nm used in step (3) of Example 1 of the present invention (right) and the ordered lattice of hexagonal non-close-packed Au nanoparticles prepared in step (5) of Example 1 of the present invention (left).

[0033] Figure 3 The scanning electron microscope photographs shown in FIG. 1 are respectively the states of Au particles at different calcination temperatures in step (5) of Example 1 of the present invention.

[0034] Figure 4 The X-ray diffraction pattern (XRD) is obtained by testing the ordered lattice of hexagonal non-close-packed Au nanoparticles prepared on the quartz substrate in Example 2 using a Philips X'Pert X-ray diffractometer.

[0035] Figure 5 The light absorption spectrum is obtained by testing the ordered lattice of hexagonal non-close-packed Au nanoparticles on the quartz substrate prepared in Example 2 using a Japanese Shimadzu UV-3101PC ultraviolet-visible-near infrared spectrophotometer (UV-Vis-NIR).

[0036] Figure 6 is a scanning electron microscope photo of the product obtained in Example 3-5. Figure 6 (a), (d), and (g) are scanning electron microscope photographs of the PDMS imprint template in step (3) of Example 3, the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprint template in step (3), and the ordered lattice of non-close-packed Au nanoparticles in step (5), respectively; Figure 6 (b), (e), and (h) are scanning electron microscope photographs of the PDMS imprint template in step (3) of Example 4, the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprint template in step (3), and the ordered lattice of non-close-packed Au nanoparticles in step (5), respectively; Figure 6 (c), (f), and (i) are scanning electron microscope photographs of the PDMS imprinting template in step (3) of Example 5, the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprinting template in step (3), and the ordered lattice of non-close-packed Au nanoparticles in step (5), respectively.

[0037] Figure 7 It is a schematic diagram of the positional relationship among tetragonal close-packed, tetragonal non-close-packed, hexagonal close-packed, and hexagonal non-close-packed in the following embodiments. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the following is a detailed description of the technology for batch preparation of non-close-packed ordered lattices based on micro / nano quasi-continuous film imprinting in the embodiment in combination with the embodiment. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the following embodiments, the structures of the arrays in tetragonal close packing, tetragonal non-close packing, hexagonal close packing, and hexagonal non-close packing are two-dimensional structures. One is that the lines connecting the centers of the structural units are in a tetragonal structure, and the other is that the lines connecting the centers of the structural units are in a hexagonal structure. When adjacent structural units are in contact, they are closely packed, and when adjacent structural units are not in contact, they are non-close packed.

[0040] Example 1

[0041] This embodiment provides a method for preparing an ordered lattice of tetragonal non-close-packed Au nanoparticles with a period of 500 nm on a silicon wafer substrate, which specifically comprises the following steps:

[0042] (1) A 4×4 inch silicon wafer substrate was cleaned to make its surface clean, and then the surface was cleaned in a plasma cleaning machine using O 2 Wash for 10 minutes to ensure that the surface of the silicon wafer substrate is hydrophilic;

[0043] (2) Fix the pretreated silicon wafer substrate in a spin coater and evenly spin coat a layer of UV-curable optical adhesive NOA61, wherein the spin coater speed is 7000 r / min, the spin coating time is 20 s, and the spin coating thickness is 2 μm;

[0044] (3) Take a PDMS (polydimethylsiloxane) imprint template with non-through uniformly arranged grooves on the surface, cover it on the UV-curable optical adhesive and fully imprint it, the shape of the grooves on the imprint template is hemispherical and the adjacent grooves are closely spaced in a square, the depth of the grooves is 250nm, and the distance between the center points of adjacent grooves located on the plane of the imprint template, that is, the period, is 500nm, and then place it under UV light for 30 minutes to make the UV-curable optical adhesive solidify to form a quasi-continuous film structure, and remove the imprint template;

[0045] (4) depositing a layer of Au film on the above-mentioned imprinted silicon wafer substrate by magnetron sputtering, wherein the magnetron sputtering current is 20 mA, the sputtering time is 4 min, and the sputtering thickness is 10 nm;

[0046] (5) The Au film-deposited silicon wafer substrate was placed in a muffle furnace for annealing and calcining at a temperature of 1050°C for 2 hours. After the annealing and calcining process, the temperature was naturally cooled to obtain a hexagonal non-close-packed Au nanoparticle lattice with a period of 500 nm.

[0047] Specifically, the process of preparing an ordered lattice of tetragonal non-close-packed Au nanoparticles with a period of 500 nm on a silicon wafer substrate in Example 1 is as follows: Figure 1 As shown, the following observations were made during the process:

[0048] The tetragonal close-packed PDMS imprint template with a period of 500 nm in step (3) of Example 1, the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprint template, and the hexagonal non-close-packed Au nanoparticle ordered lattice obtained in step (5) of Example 1 were respectively observed using a Sirion 200 field emission scanning electron microscope to obtain the following: Figure 2 The scanning electron microscope photo shown. Figure 2 (a) is a scanning electron microscope photograph of a hexagonal close-packed PDMS imprint template with a period of 500 nm in step (3) of Example 1, Figure 2 (b) is a scanning electron microscope photograph of the quasi-continuous optical adhesive hemispherical film obtained after the imprint template is imprinted in step (3) of Example 1, Figure 2 (c) is a scanning electron microscope photograph of the ordered lattice of hexagonal non-close-packed Au nanoparticles obtained in step (5) of Example 1. An optical camera was used to observe and photograph the hexagonal close-packed PDMS imprint template with a period of 500 nm in step (3) of Example 1 and the ordered lattice of non-close-packed Au nanoparticles obtained in step (5). Figure 2 (d) is an optical photograph of the 5-inch hexagonal close-packed PDMS imprint template with a period of 500 nm used in step (3) of Example 1 (right) and the 4-inch non-close-packed Au nanoparticle ordered lattice prepared in step (5) of Example 1 (left). Figure 2 It can be seen that the period of the ordered lattice of the non-close-packed Au nanoparticles prepared in Example 1 is 500 nm, the size is uniform, and the lattice is highly ordered.

[0049] The state of the Au particles during the calcination process in step (5) of Example 1 of the present invention was characterized using a Sirion 200 field emission scanning electron microscope, thereby obtaining the following: Figure 3 The scanning electron microscope photo shown in the figure shows that at 300°C, the optical glue is vaporized and removed, and the gold film melts into several particles. As the temperature rises, based on the Oswald ripening mechanism, the particles gradually fuse, and the surrounding small particles migrate and gradually fuse into the central large particle. Finally, during the 1050°C heat preservation process, all the particles fuse into a central large particle, thus forming a non-close-packed ordered lattice.

[0050] Example 2

[0051] This embodiment provides a method for preparing an ordered lattice of hexagonal non-close-packed Au nanoparticles with a period of 500 nm on a quartz substrate, which specifically includes the following steps:

[0052] (1) A quartz substrate with a size of 2×2 cm was cleaned to make its surface clean, and then the substrate was cleaned in a plasma cleaning machine using O 2 Clean for 10 minutes to ensure that the surface of the quartz substrate is hydrophilic;

[0053] (2) Fix the pretreated quartz substrate in a spin coater and evenly spin coat a layer of UV-curable optical adhesive NOA61, wherein the spin coater speed is 6000 r / min, the spin coating time is 30 s, and the spin coating thickness is 3 μm;

[0054] (3) Take a PDMS (polydimethylsiloxane) imprint template with non-through uniformly arranged grooves on the surface, cover it on the UV-curable optical adhesive and fully imprint it, the shape of the grooves on the imprint template is hemispherical and the adjacent grooves are hexagonally closely packed, the depth of the grooves is 250nm, and the distance between the center points of adjacent grooves located on the plane of the imprint template, that is, the period, is 500nm, and then place it under UV light for 30 minutes to make the UV-curable optical adhesive solidify to form a quasi-continuous film structure, and remove the imprint template;

[0055] (4) depositing a layer of Au film on the above-imprinted quartz substrate by magnetron sputtering, wherein the magnetron sputtering current is 20 mA, the sputtering time is 4 min, and the sputtering thickness is 10 nm;

[0056] (5) The quartz substrate after the Au film is deposited is placed in a muffle furnace for annealing and calcining at a temperature of 1050°C for 2 hours. After the annealing and calcining process is completed, the temperature is naturally cooled to obtain an ordered lattice of hexagonal non-close-packed Au nanoparticles with a period of 500 nm.

[0057] Specifically, the ordered lattice of hexagonal non-close-packed Au nanoparticles with a period of 500 nm on the quartz substrate prepared in Example 2 was tested as follows:

[0058] (1) A Philips X'Pert X-ray diffractometer was used to test the ordered lattice of hexagonal non-close-packed Au nanoparticles on the quartz substrate prepared in Example 2 of the present invention. Figure 4 The X-ray diffraction pattern (XRD) obtained by the test, where the ordinate is the relative intensity and the abscissa is the diffraction angle. It can be seen from the figure that the diffraction peak of the ordered lattice of hexagonal non-close-packed Au particles is very sharp, and the peak position is completely consistent with the standard value diffraction peak of Au bulk material, indicating that the ordered particles have good crystallization performance.

[0059] (2) The ordered lattice of hexagonal non-close-packed Au nanoparticles on the quartz substrate prepared in Example 2 of the present invention was tested using a Japanese Shimadzu UV-3101PC ultraviolet-visible-near-infrared spectrophotometer (UV-Vis-NIR). Figure 5 The light absorption spectrum obtained after the test, where the ordinate is the absorption intensity and the abscissa is the wavelength of the light wave. It can be seen that the ordered lattice of non-close-packed Au nanoparticles has two characteristic absorption peaks at 527nm and 661nm.

[0060] Example 3

[0061] This embodiment provides a method for preparing an ordered lattice of hexagonal non-close-packed Au nanoparticles with a period of 350 nm on a silicon wafer substrate, which specifically includes the following steps:

[0062] (1) A 4×4 inch silicon wafer substrate was cleaned to make its surface clean, and then the surface was cleaned in a plasma cleaning machine using O 2 Wash for 10 minutes to ensure that the silicon wafer surface is hydrophilic;

[0063] (2) Fix the pretreated silicon wafer substrate in a spin coater and evenly spin coat a layer of UV-curable optical adhesive NOA61, wherein the spin coater speed is 7000 r / min, the spin coating time is 20 s, and the spin coating thickness is 2 μm;

[0064] (3) Take a PDMS (polydimethylsiloxane) imprint template with non-through uniformly arranged grooves on the surface, cover it on the UV-curable optical adhesive and fully imprint it, the shape of the grooves on the imprint template is hemispherical and the adjacent grooves are hexagonally closely packed, the depth of the grooves is 125nm, and the distance between the center points of adjacent grooves located on the plane of the imprint template, that is, the period, is 350nm, and then place it under UV light for 30 minutes to make the UV-curable optical adhesive solidify to form a quasi-continuous film structure, and remove the imprint template;

[0065] (4) depositing a layer of Au film on the above-mentioned imprinted silicon wafer substrate by magnetron sputtering, wherein the magnetron sputtering current is 20 mA, the sputtering time is 4 min, and the sputtering thickness is 10 nm;

[0066] (5) The silicon wafer substrate after the Au film is deposited is placed in a muffle furnace for annealing and calcining at a temperature of 1000°C for 3 hours. After the annealing and calcining process is completed, the temperature is naturally cooled to obtain an ordered lattice of non-close-packed Au nanoparticles with a period of 350 nm.

[0067] Specifically, the following observations were made during the process of forming an ordered lattice of hexagonal non-close-packed Au nanoparticles with a period of 350 nm on a silicon wafer substrate prepared in Example 3:

[0068] The hexagonal close-packed PDMS imprint template with a period of 350 nm in step (3) of Example 3 of the present invention, the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprint template, and the hexagonal non-close-packed Au nanoparticle ordered lattice obtained in step (5) of Example 3 of the present invention were respectively observed by a Sirion200 field emission scanning electron microscope, thereby obtaining the following: Figure 6 The scanning electron microscope photo shown. Figure 6 (a) is a scanning electron microscope photograph of a hexagonal close-packed PDMS imprint template with a period of 500 nm in step (3) of Example 3 of the present invention, Figure 6 (d) is a scanning electron microscope photograph of the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprint template in step (3) of Example 3 of the present invention, Figure 6 (g) is a scanning electron microscope photograph of the ordered lattice of hexagonal non-close-packed Au nanoparticles obtained in step (5) of Example 3 of the present invention. It can be seen from the figure that the ordered lattice of non-close-packed Au nanoparticles obtained in Example 3 of the present invention has a period of 350nm, uniform size, and extremely high lattice order.

[0069] Example 4

[0070] This embodiment provides a method for preparing an ordered lattice of hexagonal non-close-packed Au nanoparticles with a period of 750 nm on a silicon wafer substrate, which specifically includes the following steps:

[0071] (1) A 4×4 inch silicon wafer substrate was cleaned to make its surface clean, and then the surface was cleaned in a plasma cleaning machine using O 2 Wash for 10 minutes to ensure that the surface of the silicon wafer substrate is hydrophilic;

[0072] (2) Fix the pretreated silicon wafer substrate in a spin coater and evenly spin coat a layer of UV-curable optical adhesive NOA61, wherein the spin coater speed is 7000 r / min, the spin coating time is 20 s, and the spin coating thickness is 2 μm;

[0073] (3) A PDMS (polydimethylsiloxane) imprint template with non-through uniformly arranged grooves on the surface is taken, and it is covered on the UV-curable optical adhesive for full imprinting. The shape of the grooves on the imprint template is pyramidal and the adjacent grooves are hexagonally closely packed. The depth of the grooves is 375nm, and the distance between the center points of adjacent grooves located on the plane of the imprint template, that is, the period, is 750nm. Then, it is placed under UV light for 30 minutes to make the UV-curable optical adhesive solidify to form a quasi-continuous film structure, and the imprint template is removed;

[0074] (4) depositing a layer of Au film on the above-mentioned imprinted silicon wafer substrate by magnetron sputtering, wherein the magnetron sputtering current is 20 mA, the sputtering time is 4 min, and the sputtering thickness is 10 nm;

[0075] (5) The Au film-deposited silicon wafer substrate was placed in a muffle furnace for annealing and calcining at a temperature of 1050°C for 3 hours. After the annealing and calcining process, the temperature was naturally cooled to obtain an ordered lattice of non-close-packed Au nanoparticles with a period of 750 nm.

[0076] Specifically, the following observations were made during the process of forming an ordered lattice of hexagonal non-close-packed Au nanoparticles with a period of 750 nm on a silicon wafer substrate prepared in Example 4:

[0077] The hexagonal close-packed PDMS imprint template with a period of 750 nm in step (3) of Example 4 of the present invention, the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprint template, and the hexagonal non-close-packed Au nanoparticle ordered lattice obtained in step (5) of Example 4 of the present invention were respectively observed using a Sirion200 field emission scanning electron microscope to obtain the following: Figure 6 The scanning electron microscope photo shown. Figure 6 (b) is a scanning electron microscope photograph of a hexagonal close-packed PDMS imprint template with a period of 750 nm in step (3) of Example 4 of the present invention, Figure 6 (e) is a scanning electron microscope photograph of the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprint template in step (3) of Example 4 of the present invention, Figure 6 (h) is a scanning electron microscope photograph of the ordered lattice of hexagonal non-close-packed Au nanoparticles obtained in step (5) of Example 4 of the present invention. It can be seen from the figure that the ordered lattice of non-close-packed Au nanoparticles obtained in Example 4 of the present invention has a period of 750nm, uniform size, and extremely high lattice order.

[0078] Example 5

[0079] This embodiment provides a method for preparing an ordered lattice of hexagonal non-close-packed Au nanoparticles with a period of 1 μm on a silicon wafer substrate, which specifically includes the following steps:

[0080] (1) A 4-inch silicon wafer substrate was cleaned to make its surface clean, and then the surface was cleaned in a plasma cleaning machine using O 2 Wash for 10 minutes to ensure that the surface of the silicon wafer substrate is hydrophilic;

[0081] (2) Fix the pretreated silicon wafer substrate in a spin coater and evenly spin coat a layer of UV-curable optical adhesive NOA61, wherein the spin coater speed is 7000 r / min, the spin coating time is 20 s, and the spin coating thickness is 2 μm;

[0082] (3) Take a PDMS (polydimethylsiloxane) imprint template with non-through uniformly arranged grooves on the surface, cover it on the UV-curable optical adhesive and fully imprint it, the shape of the grooves on the imprint template is pyramidal and the adjacent grooves are hexagonally closely packed, the depth of the grooves is 500nm, and the distance between the center points of adjacent grooves located on the plane of the imprint template, that is, the period, is 1μm, and then place it under UV light for 30min to make the UV-curable optical adhesive solidify to form a quasi-continuous film structure, and remove the imprint template;

[0083] (4) depositing a layer of Au film on the above-mentioned imprinted silicon wafer substrate by magnetron sputtering, wherein the magnetron sputtering current is 20 mA, the sputtering time is 4 min, and the sputtering thickness is 10 nm;

[0084] (5) The silicon wafer substrate after the Au film is deposited is placed in a muffle furnace for annealing and calcining at a temperature of 1100°C for 3 hours. After the annealing and calcining process is completed, the temperature is naturally cooled to obtain an ordered lattice of non-close-packed Au nanoparticles with a period of 1 μm.

[0085] Specifically, the following observations were made during the process of forming an ordered lattice of hexagonal non-close-packed Au nanoparticles with a period of 1 μm on a silicon wafer substrate prepared in Example 5:

[0086] The hexagonal close-packed PDMS imprint template with a period of 1 μm in step (3) of Example 5 of the present invention, the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprint template, and the hexagonal non-close-packed Au nanoparticle ordered lattice obtained in step (5) of Example 5 of the present invention were respectively observed by a Sirion 200 field emission scanning electron microscope to obtain the following: Figure 6 The scanning electron microscope photo shown. Figure 6 (c) is a scanning electron microscope photograph of a hexagonal close-packed PDMS imprint template with a period of 1 μm in step (3) of Example 5 of the present invention, Figure 6 (f) is a scanning electron microscope photograph of the quasi-continuous optical adhesive hemispherical film obtained after imprinting the imprint template in step (3) of Example 5 of the present invention, Figure 6 (i) is a scanning electron microscope photo of the ordered lattice of hexagonal non-close-packed Au nanoparticles obtained in step (5) of Example 5 of the present invention. It can be seen from the figure that the ordered lattice of non-close-packed Au nanoparticles obtained in Example 5 of the present invention has a period of 1 μm, uniform size, and extremely high lattice order.

[0087] Obviously, those skilled in the art can make various changes and modifications to the technology for batch preparation of non-close-packed ordered lattices based on micro / nano quasi-continuous film imprinting described in the present invention without departing from the spirit and scope of the present invention. If these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing an ordered lattice of non-close-packed noble metal nanoparticles, characterized in that: The steps include: S1, treating the flat substrate to obtain a clean and hydrophilic surface; S2, evenly coating a layer of cured optical adhesive on the surface of the flat substrate treated as above, with a thickness of 2-100 μm; S3, taking an imprint template, the surface of which is provided with non-penetrating, orderly dot-array grooves, covering the side provided with the grooves on the cured optical adhesive for imprinting, and then curing the cured optical adhesive to form a quasi-continuous film structure, and removing the imprint template; S4, depositing a layer of noble metal film with a thickness of 2-50 nm on the surface of the cured optical adhesive forming the quasi-continuous film structure; S5, placing the flat substrate with the deposited noble metal film into a muffle furnace for annealing and calcining, the calcination temperature is 500-1500° C., the time is 0.5-10 h, and the temperature is naturally lowered after the calcination, so as to obtain an ordered lattice of non-close-packed noble metal nanoparticles; The method for preparing the imprint template in step S3 is as follows: S11, adding polymer colloid microspheres to water, and assembling the polymer microsphere colloids on the water surface by a gas-liquid interface self-assembly method to obtain an ordered polymer colloid microsphere monolayer film; S12. Based on the non-destructive transfer method, the polymer colloid microsphere monolayer film is transferred to a quartz substrate, and a layer of polydimethylsiloxane (PDMS) is poured on the polymer colloid microsphere monolayer film. It is placed in a vacuum drying oven until the gaps between adjacent polymer colloid microspheres are filled with PDMS, and then placed in an oven at 40 to 100°C for curing. The PDMS is then peeled off, and the result is an imprint template with non-penetrating ordered lattice grooves.

2. The method for preparing the ordered lattice of non-close-packed noble metal nanoparticles according to claim 1, characterized in that: The material of the flat substrate in step S1 is silicon wafer, quartz or sapphire.

3. The method for preparing the ordered lattice of non-close-packed noble metal nanoparticles according to claim 1, characterized in that: In step S1, the flat substrate is cleaned by using O2 in a plasma cleaning machine to obtain a clean and hydrophilic surface.

4. The method for preparing the ordered lattice of non-close-packed noble metal nanoparticles according to claim 1, characterized in that: The cured optical adhesive in step S2 is a UV-curable optical adhesive, which is cured under a UV lamp; or, the cured optical adhesive is a thermal-curable adhesive, which is cured under heating conditions.

5. The method for preparing the ordered lattice of non-close-packed noble metal nanoparticles according to claim 1 or 4, characterized in that: In step S2, the cured optical adhesive is coated on the surface of the flat substrate by spraying or spin coating, the spin coating speed is 1000-7000 r / min, and the spin coating time is 10-300 s.

6. The method for preparing an ordered lattice of non-close-packed noble metal nanoparticles according to claim 1, characterized in that: In step S3, the aspect ratio of the grooves on the imprint template is 0.2-2.0, and the distance between the centers of adjacent grooves is 200-5000 nm.

7. The method for preparing the ordered lattice of non-close-packed noble metal nanoparticles according to claim 1 or 6, characterized in that: In step S3, the shape of the grooves on the imprint template is hemispherical or pyramidal, and adjacent grooves are distributed in a tetragonal close-packed arrangement or a hexagonal close-packed arrangement.

8. The method for preparing an ordered lattice of non-close-packed noble metal nanoparticles according to claim 1, characterized in that: In step S4, a noble metal film is deposited on the surface of the UV-curing optical adhesive by using a magnetron sputtering process, the current of the magnetron sputtering is 5-50 mA, and the sputtering time is 0.5-20 min.

9. An ordered lattice of non-close-packed noble metal nanoparticles prepared by the preparation method according to any one of claims 1 to 8.

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