Three-dimensional grating based on nano antimony sulfide and preparation method and application thereof

Abstract

The invention relates to a three-dimensional grating based on nano antimony sulfide and a preparation method and application thereof, and belongs to the technical field of optics. The three-dimensional grating based on the nanometer antimony sulfide comprises at least one grating unit, each grating unit comprises a substrate and at least two grating structures arranged periodically, and the height, perpendicular to the substrate, of each grating structure is 0.2-5 microns; the preparation raw materials of the grating structure comprise antimony sulfide nano-particles and photosensitive glue, the antimony sulfide nano-particles are spherical or sphere-like particles, and the particle size of the antimony sulfide nano-particles is 50-100 nm. Accurate preparation of the three-dimensional grating micro-nano structure is achieved, different three-dimensional structural colors can be obtained by regulating and controlling grating structure arrangement and adjusting the proportion of antimony sulfide nanoparticles, and the preparation method is wide in applicability and has high application value in the fields of dynamic display, optical anti-counterfeiting and the like.

Description

Technical Field

[0001] The present invention relates to the field of optical technologies, and particularly to a three-dimensional grating based on nano-antimony sulfide, a preparation method thereof, and an application thereof. Background Art

[0002] Currently, in the work of studying antimony sulfide micro-nano structures, the preparation of the antimony sulfide functional layer is mainly achieved through two methods: one is to directly prepare an antimony sulfide film layer on a substrate by using techniques such as chemical bath deposition, thermal evaporation, and magnetron sputtering, and to perform shape preparation on the antimony sulfide film layer by using processes such as inductively coupled plasma (ICP) etching; the other is to prepare an antimony sulfide thin film on the surface of a pre-prepared structure.

[0003] The method of directly preparing an antimony sulfide thin film by chemical bath deposition, thermal evaporation, or magnetron sputtering and performing shape preparation by using ICP etching has the problem of complex process flow; while the method of depositing an antimony sulfide thin film on the surface of a pre-prepared structure may face problems such as limited shape control ability and poor applicability to substrate materials or morphologies. In addition, both of these methods have poor repeatability and stability at the micro-nano scale, high process optimization difficulty, and high requirements for equipment and environment, resulting in increased costs.

[0004] Aiming at the shortcomings of the prior art, there is an urgent need to provide a strategy for preparing three-dimensional micro-nano structures with simple preparation, low environmental requirements, wide applicability, and precise manufacturing, so as to realize the tunable structural color of nano-antimony sulfide and provide help for the further application and popularization of nano-antimony sulfide in fields such as dynamic display and optical anti-counterfeiting. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a three-dimensional grating based on nano-antimony sulfide, a preparation method thereof, and an application thereof. The three-dimensional grating provided by the present invention can achieve the regulation of different complex structural colors by adjusting the concentration of antimony sulfide nanoparticles and the height of the grating structure, support multiple diffraction modes, and has high application value in the optical field.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a three-dimensional grating based on nano-antimony sulfide, including at least one grating unit, wherein the grating unit includes a substrate and at least two periodically arranged grating structures, and the height of the grating structure perpendicular to the substrate is 0.2 - 5 μm;

[0008] The preparation raw materials of the grating structure include antimony sulfide nanoparticles and photosensitive glue, the antimony sulfide nanoparticles are spherical or quasi-spherical particles, and the average of the antimony sulfide nanoparticles is 50 - 100 nm.

[0009] In the grating provided by the present invention, specific spherical or quasi-spherical antimony sulfide nanoparticles are used to form the components of the grating structure with the photosensitive glue raw materials, so as to accurately construct the three-dimensional micro-nano structure of the grating.

[0010] Within the specific particle size range of the above-mentioned antimony sulfide nanoparticles, due to the dipole effect of the particles dominating the interaction between light and particles and the weak multipole effect, the change in the particle size has little effect on the absorption spectrum and scattering spectrum, and the structural color of the three-dimensional grating of the present invention can be better realized; when the spherical nanoparticles are too large, mechanisms such as redshift effect and enhanced scattering will occur, destroying the designed performance of the grating structural color, resulting in color distortion, reduced efficiency and reduced detection sensitivity, which is not conducive to the further application of the grating in the optical field.

[0011] Adjusting within the specific height range of the above-mentioned grating micro-nano structure can achieve significantly different three-dimensional structural colors: as the height of the grating structure increases, the color presented gradually shifts towards the green region and then towards the red region. Specifically, as the height of the grating structure increases, the number of diffraction peaks increases and the complexity of the grating structure improves, which can support more diffraction modes. The combined action of different diffraction modes makes the grating structure present more abundant color changes, and has application prospects in the fields of dynamic display, optical anti-counterfeiting, etc.

[0012] Preferably, the height of the grating structure perpendicular to the substrate is one of 0.2μm, 0.4μm, 0.6μm, 0.8μm, 1.0μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2.0μm, 2.2μm, 2.4μm, 2.6μm, 2.8μm, 3.0μm, 3.2μm, 3.4μm, 3.6μm, 3.8μm, 4.0μm, 4.2μm, 4.4μm, 4.6μm, 4.8μm, 5.0μm or the range value of any two of them.

[0013] Preferably, the particle size of the antimony sulfide nanoparticles is one of 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, 100nm or the range value of any two of them.

[0014] Preferably, the length of the grating structure is 45-50μm and the width is 1.8-2.2μm;

[0015] Preferably, the length of the substrate is 90-100μm, the width is 90-100μm, and the height is 1-2μm;

[0016] Preferably, in the periodically arranged grating structure, the interval between adjacent grating structures is 2.5-3.5μm.

[0017] Further preferably, the grating unit includes a substrate and 8-12 periodically arranged grating structures;

[0018] Further preferably, the three-dimensional grating based on nano-antimony sulfide includes at least two grating units, and the grating units are periodically arranged to form a grating array.

[0019] Further preferably, the three-dimensional grating based on nano-antimony sulfide is periodically symmetric in the length direction and the width direction.

[0020] As a preferred solution, the grating structure has a length of 47 μm and a width of 2 μm.

[0021] As a preferred solution, the substrate has a length of 94 μm, a width of 94 μm, and a height of 1 μm.

[0022] As a preferred solution, the grating unit includes a substrate and 10 periodically arranged grating structures.

[0023] As a preferred solution, the three-dimensional grating based on nano-antimony sulfide includes 25 grating units, and the grating units are arranged in a 5×5 matrix to form a grating array.

[0024] Preferably, the preparation method of the antimony sulfide nanoparticles is as follows:

[0025] SbCl3 is dissolved in acetone, and Na2S2O3 and water are added, and the mixture is stirred for reaction. After the reaction is completed, the mixture is centrifuged and washed to obtain the antimony sulfide nanoparticles.

[0026] This invention utilizes a convenient wet chemical synthesis method to prepare antimony sulfide nanoparticles, primarily using antimony chloride (SbCl3) and sodium thiosulfate (Na2S2O3) as raw materials. Because SbCl3 is deliquescent, it readily absorbs water and undergoes hydrolysis when exposed to air, generating insoluble byproducts such as antimony oxychloride (SbOCl) and hydrogen chloride (HCl), which affect the reaction process and product purity. To avoid interference with the hydrolysis reaction, the invention uses acetone as the solvent for SbCl3 to ensure its stability and dissolution efficiency, while water is used as a reaction promoter.

[0027] The mechanism of synthesizing spherical antimony sulfide using thiosulfate solution is based on the hydrolysis and decomposition process of antimony thiosulfate complex (Sb2(S2O3)3) formed by the reaction of SbCl3 and Na2S2O3 in aqueous phase. Na2S2O3 is a reducing agent that acts as an electron donor in the reaction, reducing sulfur from a higher oxidation state to S 2 -. During the reaction, Na2S2O3 releases S 2 - ions and Sb in solution 3+Ion binding generates an intermediate thiosulfatoantimony complex (Sb2(S2O3)3). This intermediate complex is unstable under the reaction conditions and will undergo further hydrolysis and decomposition, ultimately generating nanoparticles mainly composed of antimony sulfide (Sb2S3). The specific reaction process is as follows:

[0028] 2SbCl3 + 3Na2S2O3 → Sb(S2O3)3 + 6NaCl

[0029] Sb2(S2O3)3 + 6H2O → Sb2S3 + 3HSO4 — + 3H3O +

[0030] Further preferably, in the stirring reaction, the reaction temperature is room temperature, the stirring speed is 600 - 1000 rpm, and the stirring time is 30 - 60 min;

[0031] Further preferably, the molar ratio of SbCl3 to Na2S2O3 is 1:(20 - 40).

[0032] Preferably, the antimony sulfide nanoparticles mainly exist in a non-static form.

[0033] The reaction conditions of the present invention are simple and easy to operate, only requiring a stirring reaction at room temperature. Within 10 min after the start of the reaction, the color of the reaction solution gradually changes from colorless and transparent to milky white and then further to light yellow. As the reaction time increases and reaches a specific stirring reaction time, the solution color gradually deepens to orange - red, and amorphous antimony sulfide nanoparticles are gradually formed. At the same time, under the limited specific molar ratio of reactants, it is possible to better control the particle size of the obtained antimony sulfide nanoparticles, balance the nucleation rate and particle growth, and obtain nanoparticles with a relatively uniform size distribution.

[0034] When the reaction time is too short or the ratio of Na2S2O3 is too high, aggregation or clustering effects may occur between particles, changing the distribution characteristics of the particles, resulting in non - uniform particle sizes. There may be a clustered particle distribution, and the particle size of the antimony sulfide nanoparticles is relatively small. When the reaction time is too long, the stirring speed is too fast, or the ratio of Na2S2O3 is too low, the particle size of the antimony sulfide nanoparticles will be greater than 100 nm, which is not conducive to the structural color effect of the three - dimensional grating.

[0035] As a preferred embodiment of the present invention, in the stirring reaction, the stirring speed is 600 rpm, the stirring time is 60 min, and the molar ratio of SbCl3 to Na2S2O3 is 1:30.

[0036] Under the preferred preparation conditions, antimony sulfide nanoparticles with a particle size of 60-90 nm can be stably obtained, and the repeatability is good. Although antimony sulfide nanoparticles with a main particle size distribution of 60-100 nm can also be prepared by reacting at a stirring speed of 1000 rpm for 30 min, due to the too short reaction time and relatively intense stirring, the particle size distribution of the nanoparticles is uneven.

[0037] In a second aspect, the present invention provides a method for preparing the above-mentioned three-dimensional grating based on nano-antimony sulfide, comprising the following steps:

[0038] (1) Disperse the antimony sulfide nanoparticles in propylene glycol methyl ether acetate, and then mix them with a photosensitive resin to obtain a mixed photosensitive resin;

[0039] (2) Use polydimethylsiloxane to replicate the initial template of the grating structure arrangement to obtain a PDMS soft template;

[0040] (3) Fill the grooves of the PDMS soft template with the mixed photosensitive resin, and then cover and extrude one side of the mixed photosensitive resin away from the PDMS soft template with a substrate, and after removing the solvent, perform photocuring to obtain the three-dimensional grating based on nano-antimony sulfide.

[0041] Preferably, in the step (1), the mass of the antimony sulfide nanoparticles accounts for 20-80% of the total mass of the antimony sulfide nanoparticles and the photosensitive resin;

[0042] Preferably, the refractive index n of the mixed photosensitive resin obtained in the step (1) is 1.55-1.99.

[0043] Preferably, in the step (2), the initial template of the grating structure arrangement is printed by using two-photon polymerization direct laser writing technology;

[0044] Preferably, in the step (3), the condition for removing the solvent is heating at 90-100 °C for 4-6 min, and the condition for photocuring is ultraviolet light treatment for 240-360 s.

[0045] As a preferred solution, in the step (1), the percentage of the mass of the antimony sulfide nanoparticles in the total mass of the antimony sulfide nanoparticles and the photosensitive resin is one of 21%, 30%, 45%, 53%, 64%, 77% or the range value of any two of them.

[0046] As a preferred solution, the refractive index n of the mixed photosensitive resin obtained in the step (1) is one of 1.57, 1.60, 1.66, 1.71, 1.80, 1.97 or the range value of any two of them.

[0047] Preferably, the photosensitive adhesive is Ormostamp photosensitive adhesive (Microresist), and the substrate is an ITO transparent glass substrate.

[0048] Ormostamp photosensitive adhesive is an inorganic-organic hybrid polymer, which is sensitive to light in the wavelength range of 300 - 410 nm. This property makes it an ideal material for Nanoimprint Lithography (NIL) technology. Ormostamp photosensitive adhesive is applicable not only to thermal nanoimprint lithography but also to ultraviolet nanoimprint lithography, providing flexibility for high-precision micro-nano patterning and manufacturing.

[0049] The preparation process of the three-dimensional grating based on antimony sulfide nanoparticles in the present invention can be divided into three main steps: First, through two-photon polymerization direct laser writing (TPL) technology, a three-dimensional grating structure (unit or array) with high precision is printed as an initial template, providing a basis for the subsequent transfer and replication of the structure. Then, polydimethylsiloxane (PDMS) is used to replicate the initial template to achieve efficient transfer of the three-dimensional structure: PDMS has good flexibility and high-precision transfer ability, enabling it to accurately retain the microstructural features of the original template and form a high-fidelity soft template. Finally, antimony sulfide nanoparticles are evenly dispersed in the photosensitive adhesive to form a mixed photosensitive adhesive. The mixed photosensitive adhesive is dropped on the PDMS replica, and then the substrate is covered on the surface of the mixed photosensitive adhesive. Slight extrusion is applied to make the mixed photosensitive adhesive fully fill the concave areas of the PDMS soft template, achieving close contact between the photosensitive adhesive and the substrate, and then curing is carried out.

[0050] Preferably, the preparation method further includes the following step (4):

[0051] Remove the PDMS soft template, develop it with propylene glycol methyl ether acetate for 5 - 15 min, and then perform heat treatment at 150 - 160 °C for 25 - 30 min to obtain the three-dimensional grating based on antimony sulfide nanoparticles.

[0052] The post-treatment step can further enhance the mechanical strength and stability of the mixed photosensitive adhesive structure. The three-dimensional grating prepared by the preparation method of the present invention has a complete structure, no adhesion, clear and distinguishable grating labels, and obvious structural colors.

[0053] In the third aspect, the present invention provides an application of the above-mentioned three-dimensional grating based on antimony sulfide nanoparticles in the optical field.

[0054] Preferably, the application of the three-dimensional grating based on antimony sulfide nanoparticles in the optical field includes applications in dynamic display and optical anti-counterfeiting.

[0055] The three-dimensional grating based on antimony sulfide nanoparticles provided by the present invention can comprehensively regulate the structural color through the antimony sulfide nanoparticles and the grating height, support more diffraction modes, and the combined action of different diffraction modes makes the grating structure present richer color changes.

[0056] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0057] The present invention prepares uniformly sized antimony sulfide nanoparticles through a specific wet chemical method, mixes the antimony sulfide nanoparticles with a photosensitive resin, and uses two-photon polymerization technology and a soft template method to assist in preparing a three-dimensional grating structure, realizing the precise manufacturing of three-dimensional micro-nano structures. The method adopted by the present invention simplifies the process flow, reduces the dependence on high-precision equipment, effectively reduces the production cost, improves the manufacturing efficiency, and has high process repeatability and stability. In addition, the three-dimensional grating provided by the present invention has good shape control ability and applicability, has structural color performance that can be regulated and supports multiple diffraction modes, and realizes precise regulation through antimony sulfide nanoparticles and the three-dimensional structure size, overcoming the limitations of the prior art in the preparation of complex structures and cost control, providing help for the fields of dynamic display and optical anti-counterfeiting, and having high application value. Description of the Drawings

[0058] Figure 1 It is a graph showing the change of the color of the reaction solution for preparing antimony sulfide nanoparticles with time in Experimental Example 1;

[0059] Figure 2 It is a schematic diagram of the process for preparing antimony sulfide nanoparticles in Experimental Example 1;

[0060] Figure 3 It is the SEM result diagram of the products of preparing antimony sulfide nanoparticles in Experimental Example 1 (a) reacting for 45 min and (b) reacting for 240 min;

[0061] Figure 4 It is the SEM result diagram of the products of preparing antimony sulfide nanoparticles with the molar ratio of SbCl3 to Na2S2O3 of (a) 1:10; (b) 1:20; (c) 1:30; (d) 1:40 in Experimental Example 2;

[0062] Figure 5 It is the XRD analysis diagram of the antimony sulfide nanoparticles prepared under the preferred conditions in Experimental Example 3;

[0063] Figure 6 It is the (a) SEM diagram and (b) diameter statistical distribution diagram of the antimony sulfide nanoparticles prepared under the preferred conditions in Experimental Example 3;

[0064] Figure 7SEM-EDS analysis diagrams of antimony sulfide nanoparticles prepared under the preferred conditions in Experimental Example 3: (a) SEM image; (b) antimony element analysis diagram; (c) sulfur element analysis diagram; (d) EDS energy spectrum diagram;

[0065] Figure 8 For Experimental Example 4, (a) real part of refractive index and (b) imaginary part of refractive index results diagrams of simulated three-dimensional spherical antimony sulfide nanoparticles;

[0066] Figure 9 For Experimental Example 4, electric field simulation result diagrams of three-dimensional antimony sulfide nanoparticles with different diameters at a wavelength of 650 nm: (a) 60 nm; (b) 100 nm; (c) 150 nm; (d) 200 nm;

[0067] Figure 10 For Experimental Example 4, simulation (a-b) absorption, (c-d) scattering, (e-f) extinction spectra diagrams of three-dimensional antimony sulfide nanoparticles with different diameters;

[0068] Figure 11 Model design diagram of a three-dimensional grating in Experimental Example 5;

[0069] Figure 12 For Experimental Example 5, three-dimensional grating projection spectra diagrams of simulations with (a) different materials and (b) different grating heights;

[0070] Figure 13 Schematic diagram of the preparation steps of a three-dimensional grating based on nano-antimony sulfide in Example 1;

[0071] Figure 14 For Example 1, (a) three-dimensional grating array diagram of a three-dimensional grating based on nano-antimony sulfide under 20× confocal in reflection mode; (b) structural color diagram of the grating array presented under a 5× lens of an OLYMPUS microscope in reflection mode;

[0072] Figure 15 Three-dimensional modeling measurement result diagram of a three-dimensional grating based on nano-antimony sulfide (h = 3.00 μm) in Example 1;

[0073] Figure 16 CIE chromaticity analysis result diagram of the grating structure of a three-dimensional grating based on nano-antimony sulfide (h = 2.40, 2.60, 3.00 μm) in Example 1. Detailed implementation manners

[0074] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified, the test methods used in the following embodiments are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, are reagents and materials that can be obtained from commercial channels.

[0075] Experimental Example 1

[0076] To investigate the effect of reaction time on the particle size of antimony sulfide nanoparticles in the preparation method of the present invention, antimony sulfide nanoparticles were prepared by the following method:

[0077] SbCl3 was added to acetone and stirred for 10 min to dissolve, then Na2S2O3 and water were added until the total solution volume was 11.1 mL, and the stirring reaction was carried out at room temperature of 27 °C. The molar ratio of SbCl3 to Na2S2O3 was fixed at 1:10, and the stirring speed of the reaction was 600 rpm. The reaction was carried out for 10 min, 45 min, 60 min, and 240 min respectively. After the reaction was completed, centrifugation and washing were carried out to obtain different antimony sulfide nanoparticles.

[0078] Observe the change of the color of the reaction solution with the stirring time (within 10 - 60 min). The results are as Figure 1 ; The schematic diagram of the preparation process is as Figure 2 . It can be seen that within the first 10 min after the reaction solution was completely mixed, the color of the reaction solution gradually changed from colorless and transparent to milky white, and further changed to light yellow after 3 min of reaction. As the reaction time increased, the color of the reaction solution gradually deepened to orange - red, indicating the gradual formation of amorphous antimony sulfide.

[0079] To further analyze the characteristics of antimony sulfide nanoparticles, a scanning electron microscope (SEM) was used to characterize and count the microscopic morphology and particle size of the prepared antimony sulfide nanoparticles. The change of the particle size of antimony sulfide nanoparticles with the reaction time is shown in Table 1; among them, the SEM images of the antimony sulfide nanoparticles prepared by reacting for 45 min and 240 min are respectively as Figure 3 -(a) and (b).

[0080] Table 1 Effect of reaction time on the particle size of antimony sulfide nanoparticles

[0081]

[0082] From Figure 3 it can be seen that the main morphology of antimony sulfide nanoparticles is spherical or quasi - spherical.

[0083] As can be seen from Table 1: as the reaction time increases, the average particle size of antimony sulfide nanoparticles gradually increases. The reason for this trend is that in the initial stage of the reaction, smaller particles are generated and will grow rapidly. As the reaction time increases, small particles gradually increase by the continuous deposition of atoms or ions to form larger particles. The particle sizes obtained at 10 min and 45 min after the start of the reaction are relatively small, both less than 100 nm; while the diameter of the nanoparticles generated after 240 min of reaction increases to more than 800 nm. Continuing to combine Figure 3-(b) SEM image. The surface of the generated antimony sulfide microspheres is relatively rough, and there are some aggregates of nanoparticles with small particle sizes attached to its surface and surroundings. This may be due to the increase in reaction time, which increases the probability of agglomeration of nanoparticles with smaller particle sizes in the solution, resulting in the aggregation to form larger clusters.

[0084] Experimental Example 2

[0085] To explore the effect of reaction time on the particle size of antimony sulfide nanoparticles in the preparation method of the antimony sulfide nanoparticles of the present invention, the following method was used to prepare antimony sulfide nanoparticles:

[0086] Add SbCl3 to acetone and stir for 10 min to dissolve it. Then add Na2S2O3 and water until the total solution volume is 11.1 mL, and carry out a stirring reaction at room temperature of 27 °C for 60 min. The molar ratios of SbCl3 to Na2S2O3 are 1:10, 1:20, 1:30, and 1:40 respectively. The stirring speed of the reaction is 600 rpm. After the reaction is completed, centrifuge and wash to obtain different antimony sulfide nanoparticles.

[0087] A scanning electron microscope (SEM) was used to characterize and count the microscopic morphology and particle size of the prepared antimony sulfide nanoparticles. The results are as Figure 4 and Table 2.

[0088] Table 2 Effect of the molar ratio of SbCl3 to Na2S2O3 on the particle size of antimony sulfide nanoparticles

[0089]

[0090] From Figure 4 Combined with Table 2, it can be seen that:

[0091] The obtained antimony sulfide nanoparticles are mainly spherical or quasi-spherical, and the particle surface is relatively smooth. Generally, as the ratio of the reactants SbCl3 to Na2S2O3 decreases, the average particle size of the antimony sulfide nanoparticles gradually decreases. Specifically, as the concentration of sodium thiosulfate (Na2S2O3) in the reaction solution increases, the concentration of sulfide ions (S 2- ) in the solution will increase accordingly. This condition promotes the rapid formation of crystal nuclei in the initial reaction stage. With the increase in the number of crystal nuclei, the reactants are dispersed to more growth points, resulting in a decrease in the amount of substances available for each crystal nucleus, thereby inhibiting the excessive growth of individual particles and leading to a decrease in the average particle size of the particles.

[0092] It should be noted that when the concentration of sodium thiosulfate (Na2S2O3) in the reaction solution is too high, aggregation or clustering effects may occur between particles, changing the particle distribution characteristics, resulting in uneven particle sizes, and even a clustered particle distribution. Therefore, in the process of synthesizing antimony sulfide nanoparticles by the specific room-temperature wet chemical method of the present invention, reasonably controlling the ratio of SbCl3 to Na2S2O3 can achieve a balance between the nucleation rate and particle growth, thereby obtaining a uniform particle size distribution of nanoparticles.

[0093] The above experiments 1 and 2 for exploring particle size were repeated many times, and the comprehensive preferred preparation conditions were obtained as follows: Add deionized water to a total solution volume of 11.1 mL under the condition that the molar ratio of SbCl3 to Na2S2O3 is 1:30, and stir and react for 60 min at room temperature and a stirring speed of 600 rpm. Nanoparticles with a basically uniform particle size distributed between 60 - 90 nm can be obtained, and the repeatability is good.

[0094] Experimental Example 3

[0095] To deeply analyze the characterization characteristics of the prepared antimony sulfide nanoparticles and verify the phase of the reaction products, the following experiments were carried out on the antimony sulfide nanoparticles prepared under the preferred preparation conditions (molar ratio of SbCl3 to Na2S2O3 is 1:30, reaction time 60 min):

[0096] (1) Phase characterization (X-ray diffraction analysis - XRD)

[0097] The XRD sample used for characterization was the powder obtained by vacuum drying the product at 80 °C for 120 min after the preparation of antimony sulfide nanoparticles. The measurement parameters of XRD were: Cu Kα as the target source (wavelength 0.154 nm), the scanning angle (2θ) range was from 10° to 60°, and it was kept at 25 °C, 250 °C, and 330 °C for 30 min respectively.

[0098] The obtained X-ray diffraction pattern results are as Figure 5 . After analysis: When the antimony sulfide nanoparticles synthesized by the specific room-temperature wet chemical method were not annealed (25 °C), no obvious characteristic peaks of antimony sulfide crystals appeared, indicating that the synthesized nanoparticles mainly exist in an amorphous form. This characteristic is consistent with the results of amorphous antimony sulfide thin films prepared by the chemical bath deposition method. In addition, the characteristic peaks appearing in the spectrum are consistent with the standard JCPDS card (71 - 0383) of orthorhombic antimony oxide (Sb2O3), indicating that there may be antimony oxide components in the sample. The reason for its formation may be that: the dried powder sample has a large surface area and undergoes partial oxidation to form antimony oxide in an environment with high air humidity. Therefore, the synthesized antimony sulfide nanoparticles should be subjected to a mixing glue treatment as soon as possible or stored in an oxygen-free environment to prevent their surface oxidation for better preparation in the next step.

[0099] Furthermore, it can be seen that after heating the sample in nitrogen at 250 °C and 330 °C, new characteristic peaks begin to appear in the XRD pattern, and the characteristic peaks coincide with the peak positions of PDF#01-073-0393, indicating that the state of the heat-treated sample is crystalline antimony sulfide.

[0100] (2) Morphology characterization (SEM analysis)

[0101] The prepared antimony sulfide nanoparticles were dispersed in deionized water by ultrasonic waves. Subsequently, the ultrasonically treated nanoparticle solution was dropped on the treated silicon substrate, and the sample for SEM characterization was prepared by natural drying in a vacuum environment, and SEM analysis was carried out. The results are as Figure 6 .

[0102] It can be seen that the prepared antimony sulfide nanoparticles have a regular spherical morphology and a relatively smooth surface. By measuring the particle size of the nanoparticles in the SEM image, the statistical distribution range of the diameter of the antimony sulfide nanoparticles is obtained to be 60 - 90 nm.

[0103] (3) Elemental analysis (Energy Dispersive X-ray Spectroscopy - EDS)

[0104] The SEM-EDS technique was used to perform elemental analysis on the antimony sulfide nanoparticle sample. In order to obtain more accurate elemental distribution information, independent EDS mapping analysis was carried out on single particles dispersed on the silicon wafer. The results are as Figure 7 shown.

[0105] According to the EDS analysis results, it can be seen that there are no significant impurity components (such as antimony oxychloride SbOCl) in the prepared antimony sulfide nanoparticles, and the antimony element and sulfur element are evenly distributed in the nanoparticles. This result indicates that the prepared antimony sulfide nanoparticles have a high purity. Further energy spectrum analysis shows that the atomic ratio of antimony (Sb) and sulfur (S) in the antimony sulfide nanoparticles is 48.27:51.73, which is relatively close to 2:3, indicating that the main chemical composition of the nanoparticles basically conforms to the expected chemical formula Sb2S3, and no other impurities or elements that do not conform to the stoichiometric ratio appear. Combining with the phase results of the XRD analysis, it further confirms the composition of the prepared antimony sulfide nanoparticles.

[0106] Experimental Example 4

[0107] To explore the optical properties of the prepared antimony sulfide nanoparticles as raw materials for the preparation of three-dimensional gratings, FDTD was used to simulate and specifically analyze three-dimensional spherical antimony sulfide as follows:

[0108] Spherical structures have unique advantages in functional materials due to their high surface area and short charge transport paths. In model construction, a simulation model of three-dimensional antimony sulfide spherical nanoparticles was established, and the real and imaginary parts of the refractive index are as shown in Figure 8 -(a) and (b).

[0109] To reduce the influence of boundary effects on the accuracy of optical simulation, a Perfectly Matched Layer (PML) was adopted at the boundaries of the model, and the grid size of the simulation region was set to 1 nm. In addition, a Total Field Scattered Field (TFSF) light source and an absorption and scattering cross-section analysis group were introduced into the model to more accurately calculate the interaction between electromagnetic waves and materials. The background of the simulation region is air with a refractive index of 1, and the wavelength range of the light source is set in the visible light region (400 - 800 nm) to comprehensively analyze the optical response of antimony sulfide nanospheres.

[0110] According to Mie theory, when the size of antimony sulfide nanoparticles is small (usually less than the light wavelength), the optical response of the particles is mainly dominated by the dipole effect. At this time, the interaction between light and particles shows isotropic electric dipole scattering. As the particle size increases, the electric field distribution of the nanoparticles changes, and the dipole effect is gradually affected by higher-order multipole effects (such as quadrupole, octupole, etc.), resulting in more complex scattering characteristics, stronger directionality and asymmetry.

[0111] The electric field simulation results of three-dimensional antimony sulfide nanoparticles with different diameters at a wavelength of 650 nm are as shown in Figure 9 . It can be seen that in the visible light wavelength range, the local electric field |E| of antimony sulfide nanoparticles with diameters of 60 nm, 100 nm, 150 nm, and 200 nm increases significantly with the increase of particle size.

[0112] At the same time, the absorption, scattering, and extinction spectra of the above-mentioned antimony sulfide nanoparticles with different diameters were analyzed and calculated, and the results are as shown in Figure 10It can be seen that when the diameter of antimony sulfide nanoparticles is less than 100 nm, due to the dipole effect of the particles dominating the interaction between light and particles and the weak multipole effect, the change in particle size within the range of 60 - 100 nm has little effect on the absorption spectrum and scattering spectrum. However, when the particle size exceeds 100 nm, the multipole effect begins to play a significant role, resulting in obvious changes in the characteristic peaks in the absorption spectrum and scattering spectrum. The peak intensity of the extinction spectrum increases significantly, and at the same time, the peak position redshifts (shifts towards the long-wavelength direction), and multiple absorption characteristic peaks may appear. This is because the increase in particle size enhances the coupling between the particles and the light field, making the scattering effect more significant. Larger particles may also introduce higher-order multipole modes, which are closely related to the size and shape of the particles. When the particle size approaches or exceeds the characteristic light wavelength, the newly generated resonance peak positions will gradually appear, making the absorption spectrum more complex and affecting its further application in the response effect of the grating structure.

[0113] Experimental Example 5

[0114] To explore the diffraction characteristics of the grating array and the generation mechanism of structural color under different ratios of mixed photosensitive adhesive materials and changes in the height of the grating structure, a simplified simulation model of the grating transmission spectrum was established using the FDTD simulation tool for analysis, as follows:

[0115] (I) Model Design

[0116] The overall structure of the three-dimensional grating was designed in Describe software: the periods of the grating units in the x-direction and y-direction are both 124 μm. Each grating unit consists of a substrate and 10 grating structures, and the interval period between adjacent grating structures is 3 μm; the width of each grating structure is 2 μm, the length is 47 μm, and in the z-direction, the height of the grating structure perpendicular to the substrate ranges from 0.2 - 5 μm. The designed substrate has a length of 94 μm, a width of 94 μm, and a height of 1 μm. The entire array consists of 25 grating units arranged periodically in 5 rows and 5 columns, as specifically Figure 11 shown. To facilitate subsequent observation and measurement positioning, the height of the grating design is marked under each grating unit in the format of "h = a certain height".

[0117] (II) FDTD Simulation Settings

[0118] In the FDTD simulation, a light source with a visible light wavelength range of 300 - 1100 nm was used, and the light field of air (n = 1.00) was taken as a reference to simulate the perpendicular incidence of the incident light onto the surface of the grating structure. Corresponding to the light field collected by the Olympus MPLFLN 5x objective lens with NA = 0.12 in the actual optical path, only the light field with an angle not greater than 6.9° was collected in the simulation. Due to the high symmetry of the grating structure in the x and y directions, periodic boundary conditions were adopted in the x and y directions in the simulation, and a perfectly matched layer (PML) was added to the upper and lower ends in the z direction of the model to eliminate echo interference.

[0119] When the composition of the grating structure was set to only the cured Ormostamp photosensitive resin (Microresist), the refractive index n = 1.52. At the same time, different concentrations of antimony sulfide nanoparticles in the mixed Ormostamp photosensitive resin were set (i.e., the percentage of antimony sulfide nanoparticles in the total mass of antimony sulfide nanoparticles and Ormostamp photosensitive resin), and the refractive index corresponded as follows for different ratios: 77 wt% (n = 1.97), 64 wt% (n = 1.80), 53 wt% (n = 1.71), 45 wt% (n = 1.66), 30 wt% (n = 1.60), 21 wt% (n = 1.57). The transmission spectrum results of the grating structure obtained by simulating the above-mentioned mixed Ormostamp photosensitive resin with different proportions of antimony sulfide nanoparticles are as Figure 12 .

[0120] According to Figure 12 (a), it can be seen that for the grating structures with a height of 2.6 μm prepared from different amounts of antimony sulfide nanoparticles in the mixed Ormostamp photosensitive resin, their transmission spectra also show a trend of red shift with the increase in particle content. From Figure 12 -(b), for the mixed Ormostamp photosensitive resin with 21 wt% of antimony sulfide nanoparticles, the transmission spectra of different grating heights also show a red shift phenomenon with the increase in height. These results indicate that the peak position of the transmission spectral characteristics of the grating structure is not only affected by the structure height but also significantly affected by the concentration of antimony sulfide nanoparticles in the material. By using the changes in the height of the grating structure and the refractive index of the mixed photosensitive resin at different concentrations of antimony sulfide nanoparticles, the shift of the optical resonance peak can be caused, thereby realizing the regulation of the spectral response of the grating.

[0121] Example

[0122] An embodiment of the three-dimensional grating based on antimony sulfide nanoparticles. The raw materials for preparing the grating structure are antimony sulfide nanoparticles prepared under optimized preparation conditions (molar ratio of SbCl3 to Na2S2O3 is 1:30, reaction time is 60 min) and Ormostamp photosensitive glue; the initial template parameters of the three-dimensional grating are the template size parameters in the model design of Experimental Example 5.

[0123] The preparation method of the three-dimensional grating based on antimony sulfide nanoparticles in this embodiment is as follows:

[0124] (1) Disperse the antimony sulfide nanoparticles in PGMEA at a mass ratio of 1:1 to obtain a dispersion solution, and then mix the dispersion solution with Ormostamp photosensitive glue at a volume ratio of 1:1 to obtain a mixed Ormostamp photosensitive glue with the mass ratio of antimony sulfide nanoparticles being 21 wt% (the proportion of the total mass of antimony sulfide nanoparticles and photosensitive glue).

[0125] Due to the high sensitivity of Ormostamp photosensitive glue to light and temperature, special attention should be paid to avoiding excessive temperature and light during the mixing process to prevent the photosensitive glue from curing prematurely during the dispersion process.

[0126] (2) Print an initial template with a highly precise three-dimensional grating structure array through two-photon polymerization direct laser writing (TPL) technology, and then use polydimethylsiloxane (PDMS) to replicate the initial template to obtain a PDMS soft template with the reverse structure of the initial template.

[0127] (3) Drop the mixed Ormostamp photosensitive glue obtained in step (1) onto the reverse structure of the PDMS soft template for filling, and then cover the surface of the mixed photosensitive glue with a substrate ITO transparent glass substrate, and gently squeeze to make the mixed photosensitive glue fully fill the concave area of the PDMS soft template, so that the mixed photosensitive glue is in close contact with the PDMS soft template and the substrate; then heat at 95 °C for 5 min to remove PGMEA in the mixed photosensitive glue, and cure under ultraviolet light for 300 s.

[0128] (4) Remove the PDMS soft template, develop the sample after curing the mixed Ormostamp photosensitive glue with PGMEA for 10 min, and heat the structure on a heating table at 150 °C for 30 min to obtain the three-dimensional grating based on antimony sulfide nanoparticles.

[0129] The preparation steps of the above three-dimensional grating based on antimony sulfide nanoparticles are schematically shown as Figure 13 ... Place the prepared three-dimensional grating array based on antimony sulfide nanoparticles under a confocal microscope for observation, and the results are as Figure 14Shown as follows: Under the 20× lens, the prepared three-dimensional grating array structure can be clearly observed to be complete, without adhesion, and the grating labels are clearly distinguishable; under the 5× lens of the OLYMPUS microscope, the three-dimensional grating array has an obvious structural color.

[0130] Furthermore, laser three-dimensional modeling measurement was carried out on the three-dimensional grating with the label "h = 3.00 μm", and the results are as Figure 15 : It can be seen that the actual height of the measured grating structure is 2.4 μm; there is a height loss of about 0.6 μm in the replication accuracy of the hybrid photosensitive adhesive in terms of the structural height, which may be related to the material properties or curing shrinkage of the Ormostamp photosensitive adhesive.

[0131] Furthermore, to explore the performance of the three-dimensional grating based on antimony sulfide nanoparticles in this embodiment, by analyzing the CIE chromaticity of the grating structures with different height grating labels "h = 2.40, 2.60, 3.00 μm" prepared from 21wt% of the hybrid Ormostamp photosensitive adhesive (n = 1.57), the results are as Figure 16 . It can be seen that as the grating height increases, the color presented by the structure gradually shifts towards the green region and then towards the red region; specifically, as the height of the grating structure increases, the number of diffraction peaks increases, the complexity of the grating structure increases, and more diffraction modes can be supported. The combined effect of different diffraction modes makes the grating structure present a more abundant color change. This result is consistent with the result of the simulation experiment in Experimental Example 5, further verifying that the three-dimensional grating based on antimony sulfide nanoparticles provided by the present invention can achieve the regulation of structural color.

[0132] In summary, the antimony sulfide nanoparticles prepared by the specific wet chemical method of the present invention, when mixed with the photosensitive adhesive as the raw material for preparing the three-dimensional grating structure, have good shape control ability and applicability, and overcome the limitations of the prior art in the preparation of complex structures and cost control, etc.; at the same time, the present invention uses two-photon polymerization technology and soft template method to assist in the preparation of the three-dimensional grating structure, which not only simplifies the process flow, reduces the dependence on high-precision equipment, but also effectively reduces the production cost and improves the manufacturing efficiency. The three-dimensional grating based on antimony sulfide nanoparticles provided by the present invention can comprehensively regulate the structural color through the antimony sulfide nanoparticles and the grating height, support more diffraction modes, and the combined effect of different diffraction modes makes the grating structure present a more abundant color change, which has high application value in the fields of dynamic display and optical anti-counterfeiting.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A three-dimensional grating based on nano-antimony sulfide, characterized in that, Comprising at least one grating unit, the grating unit comprising a substrate and at least two periodically arranged grating structures, the height of the grating structures perpendicular to the substrate being 0.2 - 5 μm; The raw materials for preparing the grating structures include antimony sulfide nanoparticles and photosensitive glue, the antimony sulfide nanoparticles being spherical or quasi-spherical particles, and the particle size of the antimony sulfide nanoparticles being 50 - 100 nm.

2. The three-dimensional grating based on nano-antimony sulfide according to claim 1, characterized in that, The length of the grating structures is 45 - 50 μm, and the width is 1.8 - 2.2 μm; And / or, the length of the substrate is 90 - 100 μm, the width is 90 - 100 μm, and the height is 1 - 2 μm; And / or, in the periodically arranged grating structures, the interval between adjacent grating structures is 2.5 - 3.5 μm.

3. The three-dimensional grating based on nano-antimony sulfide according to claim 2, wherein The grating unit comprises a substrate and 8 - 12 periodically arranged grating structures; And / or, the three-dimensional grating based on nano-antimony sulfide comprises at least two grating units, and the grating units are periodically arranged to form a grating array; And / or, the three-dimensional grating based on nano-antimony sulfide is periodically symmetric in the length direction and the width direction.

4. The three-dimensional grating based on nano-antimony sulfide according to claim 1, characterized in that, The preparation method of the antimony sulfide nanoparticles is as follows: Dissolve SbCl3 in acetone, add Na2S2O3 and water, stir and react, and after the reaction is completed, centrifuge and wash to obtain the antimony sulfide nanoparticles.

5. The three-dimensional grating based on nano-antimony sulfide according to claim 4, wherein In the stirring reaction, the reaction temperature is room temperature, the stirring speed is 600 - 1000 rpm, and the stirring time is 30 - 60 min; And / or, the molar ratio of SbCl3 to Na2S2O3 is 1:(20 - 40).

6. The preparation method of the three-dimensional grating based on nano-antimony sulfide according to any one of claims 1-5, characterized in that, Comprising the following steps: (1) Disperse the antimony sulfide nanoparticles in propylene glycol methyl ether acetate, and then mix with the photosensitive glue to obtain a mixed photosensitive glue; (2) Use polydimethylsiloxane to replicate the initial template of the grating structure arrangement to obtain a PDMS soft template; (3) Fill the grooves of the PDMS soft template with the mixed photosensitive glue, and then cover and extrude the side of the mixed photosensitive glue away from the PDMS soft template with the substrate, and after removing the solvent, perform photocuring to obtain the three-dimensional grating based on nano-antimony sulfide.

7. The preparation method of the three-dimensional grating based on nano-antimony sulfide according to claim 6, characterized in that, In the step (1), the mass of the antimony sulfide nanoparticles accounts for 20 - 80% of the total mass of the antimony sulfide nanoparticles and the photosensitive glue; And / or, the refractive index n of the mixed photosensitive glue obtained in the step (1) is 1.55 - 1.

99.

8. The preparation method of the three-dimensional grating based on nano-antimony sulfide according to claim 6, wherein, In the step (2), the initial template of the grating structure arrangement is printed by using two-photon polymerization direct laser writing technology; And / or, in the step (3), the condition for removing the solvent is heating at 90 - 100 °C for 4 - 6 min, and the condition for photocuring is ultraviolet light treatment for 240 - 360 s.

9. The preparation method of the three-dimensional grating based on nano-antimony sulfide according to claim 6, characterized in that, The preparation method further comprises the following step (4): Remove the PDMS soft template, develop with propylene glycol methyl ether acetate for 5 - 15 min, and then perform heat treatment at 150 - 160 °C for 25 - 30 min to obtain the three-dimensional grating based on nano-antimony sulfide.

10. Application of the three-dimensional grating based on nano-antimony sulfide according to any one of claims 1 - 5 in the optical field.

Images