Non-close-packed rainbow superlattice two-dimensional thin film, and preparation method and application thereof

Abstract

This invention discloses a non-close-packed rainbow superlattice two-dimensional thin film, its preparation method, and its applications, belonging to the field of metal nanomaterials technology. First, noble metal nanoparticles are modified with polystyrene-thiol as the modifier. Then, through the solvent effect, the hydrophobic interaction between the modified polystyrene-thiol and the block copolymer polystyrene-polyacrylic acid ligand is enhanced, causing the discrete noble metal nanoparticles to assemble into clusters. The clusters are dispersed in water, and a perfluorodecylthiol anhydrous ethanol / n-hexane solution is added, resulting in a non-close-packed rainbow superlattice two-dimensional thin film at the liquid-liquid interface. This invention achieves the control of the optical properties of the superlattice two-dimensional thin film, exhibiting strong versatility and applicability to noble metal nanoparticles with various morphologies. The prepared non-close-packed rainbow superlattice two-dimensional thin film possesses rich and tunable colors, showing promising application prospects in display, sensing, and anti-counterfeiting fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal nanomaterials, and particularly to a non-close-packed rainbow superlattice two-dimensional film and a preparation method and application thereof. BACKGROUND

[0002] Gold nanoparticles have been extensively studied in the past few decades due to their unique optical, electrical and catalytic properties. Gold nanoparticle superlattices (NPSL) are formed by the ordered assembly of gold nanoparticles as basic structural units according to a certain spatial arrangement. Gold nanoparticle superlattices not only retain the characteristics of their basic structural units, but also derive many new collective properties, such as plasmonic coupling effects, quantum confinement effects, etc. These properties different from single gold nanoparticles make gold nanoparticle superlattices exhibit great application potential in the fields of sensing, catalysis, optoelectronic devices, biomedicine, etc.

[0003] The optical properties of gold nanoparticles are primarily determined by localized surface plasmon resonance (LSPR), and their resonance wavelength is influenced by particle size, shape, and the surrounding medium. In NPSL, the spacing between gold nanoparticles is one of the key structural parameters for controlling their optical properties. The spacing between basic structural units not only determines the coupling strength of LSPR but also significantly affects the local electromagnetic field distribution characteristics and photon-exciton interaction efficiency, thus having a decisive impact on the light absorption characteristics, scattering behavior, and nonlinear optical response of the superlattice. When multiple gold nanoparticles are assembled into an NPSL, if the particle spacing is reduced to near or less than their own diameter, the reduced spacing leads to an increase in density, causing the near-field electromagnetic fields of the gold nanoparticles to overlap and generating a near-field coupling effect. This effect causes a redshift of the resonance peak and enhanced absorption / scattering. Some scientists have pointed out that when the particle size is ten times larger than the interparticle spacing, the three-dimensional crystal of plasmon nanoparticles can achieve deep and strong coupling under environmental conditions. By precisely controlling the spacing between gold nanoparticle dimers at 1-2 nm, a hotspot effect can be generated, resulting in an electromagnetic field enhancement factor as high as 106 times. However, while small-pitch NPSLs can achieve lattice resonance and improve detection sensitivity, they cannot retain the color characteristics of the particle solution itself. Conversely, if the spacing between gold nanoparticles increases, typically exceeding three times the particle diameter, the interaction between the gold nanoparticles weakens, leading to a sharp decrease in electromagnetic coupling. The resulting NPSL exhibits optical behavior similar to that of individual particles dispersed in a solution, and its macroscopic color is also similar to that of the particle solution. This means that the macroscopic color of the NPSL can be determined by the LSPR of individual particles. This spacing-dependent optical response characteristic provides an important basis for the controllable preparation and functional design of NPSLs. Therefore, by controlling the particle spacing of NPSLs, continuous and even reversible control of their optical properties can be achieved, thereby meeting the needs of different application scenarios.

[0004] Chinese patent document CN117488409A discloses a noble metal nanoparticle superlattice film and its assembly method. The invention involves vigorously mixing noble metal nanoparticles with a toluene or n-hexane solution containing trace amounts of ligands (oleylamine, oleic acid, or dodecanethiol) to induce phase transfer and obtain a toluene or n-hexane solution containing noble metal nanoparticles. Then, the toluene or n-hexane solution containing noble metal nanoparticles is injected above the interface of ethylene glycol or diethylene glycol to form a liquid-air interface. Natural evaporation generates a monolayer superlattice film, which is then optimized using ethanol to obtain the noble metal nanoparticle superlattice film. Chinese patent document CN107699954A discloses a strongly coupled gold nanoscale superlattice structure. The method involves placing a cleaned solid substrate in a boiling solution of piranhas for a period of time to perform a negatively charged hydroxylation treatment on the surface. The treated and dried substrate is then vertically immersed in a high-concentration solution of positively charged 32-dodecahedral gold nanoparticles. The substrate is then slowly separated vertically from the liquid surface. The ambient temperature during the entire self-assembly process is maintained within a certain range. After the self-assembly process is completed, a single-layer gold nanoscale supercrystalline thin film structure can be formed on a large scale at one end of the substrate.

[0005] Traditional assembly methods based on solvent evaporation (such as liquid-liquid interface self-assembly and gas-liquid interface self-assembly) can usually only obtain NPSL structures with small interparticle spacing. This is mainly because the dominant forces in the assembly process of gold nanoparticles are short-range interactions such as van der Waals forces and capillary forces, which result in small interparticle spacing. Summary of the Invention

[0006] To increase the spacing between gold nanoparticles in a gold nanoparticle superlattice and to regulate optical properties to meet the needs of different applications, this invention proposes a method for preparing a non-close-packed rainbow superlattice two-dimensional thin film based on polymer long-range interaction regulation. This method is easy to operate, has strong universality, and is applicable to noble metal nanoparticles with various morphologies.

[0007] The specific technical solution adopted is as follows: A method for preparing a non-close-packed rainbow superlattice two-dimensional thin film includes the following steps: (1) Polystyrene-thiol was modified on the surface of noble metal nanoparticles. Poor solvent and polystyrene-polyacrylic acid were added to the organic solution of the modified noble metal nanoparticles. After heating and washing with water, clusters of noble metal nanoparticles were obtained. (2) The clusters were dispersed in water and an anhydrous ethanol / n-hexane solution of perfluorodecylthiol was added to obtain a non-close-packed rainbow superlattice two-dimensional thin film at the liquid-liquid interface. The noble metal nanoparticles mentioned are gold nanoparticles or core-shell structured nanoparticles with a gold shell. In the organic solution of the modified noble metal nanoparticles, the solvent is N,N-dimethylformamide or tetrahydrofuran.

[0008] This invention relates to the preparation of non-close-packed rainbow superlattice two-dimensional thin films based on the regulation of long-range polymer interactions. It utilizes polystyrene-thiol to modify the surface of noble metal nanoparticles, enhancing the hydrophobic interaction between polystyrene-thiol and polystyrene-polyacrylic acid ligands through a solvent effect. This assembles discrete noble metal nanoparticles into clusters, the basic assembly unit of the superlattice two-dimensional film. Furthermore, the solvent effect weakens the hydrophobic interaction between polystyrene-thiol and polystyrene-polyacrylic acid ligands, allowing for the directional rearrangement of long-range polymer interactions within the clusters. Simultaneously, perfluorodecyl mercaptan creates a third-phase microenvironment, lowering the energy barrier and enabling the controllable assembly of noble metal nanoparticles at the liquid-liquid interface, resulting in a non-close-packed rainbow superlattice two-dimensional thin film.

[0009] Preferably, the noble metal nanoparticles are gold nanospheres, gold pyramids, gold octahedrons, gold triangular plates, or gold-coated silver nanoparticles with a particle size of 10-100 nm, and can be synthesized according to the methods described in the prior art.

[0010] Preferably, the molecular weight of polystyrene-thiol is 5300-50000. Noble metal nanoparticles are added to an organic solution containing polystyrene-thiol under ultrasonic conditions and left to stand overnight to complete the modification of the surface of the noble metal nanoparticles with polystyrene-thiol.

[0011] Preferred unsuitable solvents include water, methanol, or ethanol.

[0012] Preferably, the molecular weight of the polystyrene-polyacrylic acid is 17,000-21,000, wherein the molecular weight of the polyacrylic acid portion is 1,000-4,200.

[0013] Furthermore, the preferred amount of polystyrene-thiol is 30-80 μL, 2 mg / mL, and the preferred amount of polystyrene-polyacrylic acid is 200-600 μL, 8 mg / mL.

[0014] Preferably, the heating conditions are 90-110 ℃ for 50-60 min, and most preferably 100 ℃ for 1 h.

[0015] Preferably, in the anhydrous ethanol / n-hexane solution of perfluorodecylthiol, the concentration of perfluorodecylthiol is 8-12 mM, most preferably 10 mM, and the volume ratio of anhydrous ethanol to n-hexane is 1-3:1, most preferably 2:1.

[0016] Specifically, an anhydrous ethanol / n-hexane solution of perfluorodecylthiol is added, and after the upper layer of n-hexane evaporates, a non-close-packed rainbow superlattice two-dimensional thin film is obtained at the liquid-liquid interface.

[0017] The present invention also provides a method for preparing non-close-packed rainbow superlattice two-dimensional thin films, which yields non-close-packed rainbow superlattice two-dimensional thin films.

[0018] This non-close-packed rainbow superlattice two-dimensional thin film is composed of polymer-modified noble metal nanoparticles with a large spacing of 28.76 nm between them. By controlling the morphology or type of the noble metal nanoparticles, superlattice two-dimensional thin films with colors of pink, brown, purple, blue, green, and yellow can be selectively obtained.

[0019] The present invention also provides the application of the aforementioned non-close-packed rainbow superlattice two-dimensional thin film in the fields of display, sensing or anti-counterfeiting.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention regulates the aggregation and dissociation of hydrophobic polymers through solvation, further regulates the assembly behavior of noble metal nanoparticles, and utilizes perfluorodecyl mercaptan to reduce the energy barrier to achieve controllable assembly of noble metal nanoparticles, ultimately obtaining a non-close-packed rainbow superlattice two-dimensional thin film.

[0021] (2) This invention utilizes the interaction force between long-chain ligand polymers to overcome the van der Waals attraction between noble metal nanoparticles, thereby realizing the long-range interaction between noble metal nanoparticles, increasing the spacing between noble metal nanoparticles, and realizing the optical property control of superlattice two-dimensional thin films.

[0022] (3) The method of the present invention has strong universality and is applicable to gold nanoparticles with various morphologies or core-shell structured nanoparticles with gold shells. The non-close-packed rainbow superlattice two-dimensional thin film prepared has the characteristics of rich and adjustable colors and has potential application value in display, sensing, anti-counterfeiting and other fields. Attached Figure Description

[0023] Figure 1 This is a TEM image of the gold nanospheres prepared in Example 1.

[0024] Figure 2 This is a TEM image of the gold cone obtained in Example 2.

[0025] Figure 3 This is a TEM image of the gold octahedron prepared in Example 3.

[0026] Figure 4 This is a TEM image of the gold triangle piece obtained in Example 4.

[0027] Figure 5 This is a TEM image of the gold-coated silver nanoparticles prepared in Example 5.

[0028] Figure 6This is a TEM image of the gold-coated silver nanoparticles prepared in Example 6.

[0029] Figure 7 This is a TEM image of the clusters formed by assembling gold nanospheres in Example 1.

[0030] Figure 8 This is a photograph of the pink non-close-packed superlattice two-dimensional thin film formed by the cluster dissociation assembly of Example 1.

[0031] Figure 9 This is a TEM image of the pink non-close-packed superlattice two-dimensional thin film prepared in Example 1.

[0032] Figure 10 This is a statistical diagram of the particle spacing of the pink non-close-packed superlattice two-dimensional thin film prepared in Example 1.

[0033] Figure 11 These are photographs of the non-close-packed rainbow superlattice two-dimensional thin films prepared in Examples 1-6. Detailed Implementation

[0034] To make the objectives, features, and advantages of this invention more apparent and understandable, a detailed description is provided below through specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the invention can be combined appropriately without mutual conflict.

[0035] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer. Contents not described in detail in this specification are prior art known to those skilled in the art. Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0036] Example 1 (1) Preparation of gold nanospheres Seed synthesis: Gold nanosphere seeds were prepared using the classic crystal seeding method. First, a seed solution was prepared by mixing 9.9 mL of CTAB solution (100 mM) with HAuCl4 (100 μL, 25 mM) until homogeneous. Then, 600 μL of freshly prepared NaBH4 solution (0.01 M) was quickly added using ice water. The mixture was incubated in a 30°C water bath for 3 h to mature the seed solution. 2 mL of the seed solution was added to 80 mL of hexadecyltrimethylammonium chloride (CTAC) solution (200 mM) and stirred until homogeneous. Then, 60 mL of freshly prepared AA solution (100 mM) was added, followed by the rapid addition of HAuCl4 (80 mL, 0.5 mM). The mixture was stirred at 300 rpm for 15 min to obtain the first growth solution, which was wine-red in color. Take 18 mL of the precipitate from the first growth solution, centrifuge (16000 rpm, 20 min), disperse it in CTAC solution (80 mL, 0.10 M), sonicate for 10 min, add AA solution (5.2 mL, 0.010 M), stir for 10 min, and slowly add HAuCl4 (0.5 mM) dropwise at a rate of 20 mL / h in a 30℃ water bath until the solution color changes from wine red to purple and then to deep red, obtaining the gold nanosphere solution. The TEM image of the gold nanospheres is shown below. Figure 1 As shown, its average diameter is approximately 34 nm.

[0037] (2) Preparation of clusters The experimental steps for synthesizing gold nanosphere clusters are as follows: Take the gold nanosphere solution (5 mL, OD = 1.2) prepared in step (1) and centrifuge it twice (10000 rpm, 10 min). Disperse the gold nanosphere precipitate obtained by centrifugation into 2 mL of N,N-dimethylformamide solution under ultrasonic conditions. Add 60 μL of 2 mg / mL polystyrene-thiol (molecular weight 20000) solution to the solution in advance. After dispersion, the solution turns red. Let it stand overnight to allow the gold nanospheres to fully combine with the polystyrene-thiol. Then, 360 μL of deionized water was added to the above solution, and after standing for 10 min, 200 μL of 8 mg / mL polystyrene-polyacrylic acid solution (molecular weight 16000-3700) was added, followed by 540 μL of deionized water. The above mixed solution was heated at 100℃ for 1 h, and then cooled to room temperature. After centrifugation (3200 rpm, 20 min), the solution was dispersed twice in water to obtain gold nanosphere clusters.

[0038] TEM images of gold nanospheres assembling into clusters after enhancing the hydrophobic interaction between polystyrene-thiol and the block copolymer polystyrene-polyacrylic acid ligands using solvents are shown below. Figure 7 As shown.

[0039] (3) Preparation of non-close-packed superlattice two-dimensional thin films Perfluorodecylthiol was dispersed in a solution of anhydrous ethanol and n-hexane in a volume ratio of 2:1 to prepare a perfluorinated solution with a concentration of 10 mM of perfluorodecylthiol. The cluster solution prepared in step (2) was dispersed in 10 mL of water and transferred to a 50 mL quartz beaker. 10 mL of perfluorinated solution was quickly injected into the solution, and the formation of a two-dimensional film could be quickly observed. After the upper n-hexane solution evaporated, a pink non-close-packed superlattice two-dimensional thin film could be obtained.

[0040] Optical images of pink, non-close-packed superlattice two-dimensional thin films formed by the dissociation and assembly of clusters after the hydrophobic interaction between polystyrene-thiol and the block copolymer polystyrene-polyacrylic acid ligands was weakened by using solvents. Figure 8 As shown, the TEM image is as follows Figure 9 As shown, the low-magnification view on the left reveals a large area of ​​dispersed nanoparticles, while the high-magnification view on the right clearly shows the uniform size of these particles and the large spacing between them. The spacing statistics are as follows: Figure 10 As shown, the spacing is 28.76±2.94nm.

[0041] Example 2 Different morphologies of gold nanoparticles correspond to different local surface plasmon resonance peaks. By using gold nanoparticles with different morphologies to prepare non-close-packed superlattice two-dimensional thin films, their macroscopic colors can be tuned.

[0042] (1) Preparation of gold cone Seed synthesis: Gold nanosphere seeds were prepared using the classic crystal seeding method. First, the seed solution was prepared by adding 3.5 mL of ultrapure water and 1 mL of HAuCl4 (25 mM) to CTAC solution (5 mL 0.1 M) and stirring until homogeneous. Then, 1 mL of citric acid (CA) solution (0.05 M) was added, followed by the rapid addition of 250 μL of freshly prepared NaBH4 solution (0.025 M) using ice water. The solution was then incubated in an 80℃ water bath for 90 min to obtain the seed solution. Then, the growth medium was prepared by adding HAuCl4 (590 μL, 100 mM) and AgNO3 solution (3 mL, 0.01 M) to CTAB solution (100 mL, 0.1 M). After stirring for 10 min, HCl (1 mL, 12 M) was added, followed by freshly prepared AA solution (1.5 mL, 0.1 M). 3 mL of seed culture was added to the growth medium, and the mixture was stirred thoroughly. The mixture was then incubated in a 30°C water bath for 7 h. Purification was then performed using dodecyl dimethyl benzyl ammonium chloride (BDAC) to obtain the gold beta solution. The TEM image of the gold beta is shown below. Figure 2As shown, its average side length is approximately 60 nm.

[0043] (2) Preparation of clusters The steps and parameters are the same as in Example 1, except that the gold nanospheres are replaced with gold cones.

[0044] (3) Preparation of non-close-packed superlattice two-dimensional thin films Using the clusters from step (2), a non-close-packed superlattice two-dimensional thin film was prepared. The preparation steps and parameters were the same as in Example 1, resulting in a brown non-close-packed superlattice two-dimensional thin film. Optical images are shown below. Figure 11 As shown.

[0045] Example 3 (1) Preparation of gold octahedron First, prepare the seed culture by adding 4.75 mL of ultrapure water and HAuCl4 (250 μL, 10 mM) to CTAC solution (5 mL 0.2 M) and stirring until homogeneous. Then, quickly add freshly prepared NaBH4 solution (450 μL, 0.02 M) using ice water and let it stand in a 30℃ water bath for 1 h to obtain the seed culture. Next, growth solution A and growth solution B were prepared identically: 4.53 mL of ultrapure water, 250 μL of HAuCl4 (10 mM), and 5 μL of KI (0.01 M) were added to 5 mL of CTAC solution (0.2 M). After thorough mixing, 220 μL of freshly prepared AA (0.025 M) was added. 55 μL of seed culture was added to growth solution A, and the mixture was stirred for approximately 5 seconds until the solution turned red. Immediately afterward, 55 μL of growth solution A was added to growth solution B, and the mixture was stirred for 5 seconds. The solution was then incubated in a 30°C water bath for 15 minutes to obtain the gold octahedron. The TEM image of the gold octahedron is shown below. Figure 3 As shown, its average side length is approximately 24 nm.

[0046] (2) Preparation of clusters The steps and parameters are the same as in Example 1, except that the gold nanospheres are replaced with gold octahedrons.

[0047] (3) Preparation of non-close-packed superlattice two-dimensional thin films Using the clusters from step (2), a non-close-packed superlattice two-dimensional thin film was prepared. The preparation steps and parameters were the same as in Example 1, resulting in a purple non-close-packed superlattice two-dimensional thin film. Optical images are shown below. Figure 11 As shown.

[0048] Example 4 (1) Preparation of the gold triangle sheet First, mix CTAC solution (9.5 mL, 0.1 M) and HAuCl4 (80 μL, 0.025 M) thoroughly, then quickly add freshly prepared NaBH4 solution (450 μL, 0.01 M) using ice water. Let it stand in a 30℃ water bath for 2 h to mature and obtain the seed culture. Then, growth solution A was prepared by adding HAuCl4 (80 μL, 0.025 M) and KI solution (25 μL, 0.01 M) to CTAC solution (9.7 mL, 0.1 M), mixing thoroughly, and then adding freshly prepared AA solution (185 μL, 0.04 M). Growth solution B was prepared by adding HAuCl4 (240 μL, 0.025 M) and KI solution (90 μL, 0.01 M) to CTAC solution (29.1 mL, 0.1 M), mixing thoroughly, and then adding freshly prepared AA solution (500 μL, 0.04 M). Next, 25 μL of seed culture was added to growth solution A, and the mixture was stirred for approximately 5 seconds until the solution turned red. Immediately afterward, 200 μL was added to growth solution B, stirred for 5 seconds, and then allowed to stand for 10 minutes. The solution was repeatedly purified using CTAC solutions of different concentrations to obtain the gold triangle pieces. TEM images of the gold triangle pieces are shown below. Figure 4 As shown, its average side length is approximately 83 nm.

[0049] (2) Preparation of clusters The steps and parameters are the same as in Example 1, except that the gold nanospheres are replaced with gold triangular sheets.

[0050] (3) Preparation of non-close-packed superlattice two-dimensional thin films Using the clusters from step (2), a non-close-packed superlattice two-dimensional thin film was prepared. The preparation steps and parameters were the same as in Example 1, resulting in a blue non-close-packed superlattice two-dimensional thin film. Optical images are shown below. Figure 11 As shown.

[0051] Example 5 (1) Preparation of gold-coated silver nanoparticles Add CTAC (5 mL 0.1 M), AgNO3 (3 mL 0.01 M), and AA (3 mL 0.1 M) to 5 mL of the gold nanosphere solution prepared in Example 1. Stir in a 60°C water bath for 4 h. After cooling, centrifuge at 6000 rpm for 5 min. Discard the supernatant, disperse the precipitate with 5 mL of deionized water to obtain gold-coated silver nanoparticles. TEM images of the gold-coated silver nanoparticles are shown below. Figure 5 As shown, its average side length is approximately 47 nm.

[0052] (2) Preparation of clusters The steps and parameters are the same as in Example 1, except that the gold nanospheres are replaced with gold-coated silver nanoparticles.

[0053] (3) Preparation of non-close-packed superlattice two-dimensional thin films Using the clusters from step (2), a non-close-packed superlattice two-dimensional thin film was prepared. The preparation steps and parameters were the same as in Example 1, resulting in a green non-close-packed superlattice two-dimensional thin film. Optical images are shown below. Figure 11 As shown.

[0054] Example 6 (1) Preparation of gold-coated silver nanoparticles Add CTAC (5 mL 0.1 M), AgNO3 (1250 μL 0.01 M), and AA (1250 μL 0.1 M) to 5 mL of the gold nanosphere solution prepared in Example 1. Stir in a 60°C water bath for 4 h. After cooling, centrifuge at 6000 rpm for 5 min. Discard the supernatant and disperse the precipitate with 5 mL of deionized water to obtain gold-coated silver nanoparticles. TEM images of the gold-coated silver nanoparticles are shown below. Figure 6 As shown, its average side length is approximately 24 nm.

[0055] (2) Preparation of clusters The steps and parameters are the same as in Example 1, except that the gold nanospheres are replaced with gold-coated silver nanoparticles.

[0056] (3) Preparation of non-close-packed superlattice two-dimensional thin films Using the clusters from step (2), a non-close-packed superlattice two-dimensional thin film was prepared. The preparation steps and parameters were the same as in Example 1, resulting in a yellow non-close-packed superlattice two-dimensional thin film. Optical images are shown below. Figure 11 As shown.

[0057] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a non-close-packed rainbow superlattice two-dimensional thin film, characterized in that, Includes the following steps: (1) Polystyrene-thiol was modified on the surface of noble metal nanoparticles. Poor solvent and polystyrene-polyacrylic acid were added to the organic solution of the modified noble metal nanoparticles. After heating and washing with water, clusters of noble metal nanoparticles were obtained. (2) The clusters were dispersed in water and an anhydrous ethanol / n-hexane solution of perfluorodecylthiol was added to obtain a non-close-packed rainbow superlattice two-dimensional thin film at the liquid-liquid interface. The noble metal nanoparticles mentioned are gold nanoparticles or core-shell structured nanoparticles with a gold shell. In the organic solution of the modified noble metal nanoparticles, the solvent is N,N-dimethylformamide or tetrahydrofuran.

2. The method for preparing a non-close-packed rainbow superlattice two-dimensional thin film according to claim 1, characterized in that, The noble metal nanoparticles are gold nanospheres, gold pyramids, gold octahedrons, gold triangular plates, or gold-coated silver nanoparticles with a particle size of 10-100 nm.

3. The method for preparing a non-close-packed rainbow superlattice two-dimensional thin film according to claim 1, characterized in that, Polystyrene-thiol has a molecular weight of 5300-50000. Noble metal nanoparticles are added to an organic solution containing polystyrene-thiol under ultrasonic conditions and left to stand overnight to complete the modification of the surface of the noble metal nanoparticles with polystyrene-thiol.

4. The method for preparing a non-close-packed rainbow superlattice two-dimensional thin film according to claim 1, characterized in that, Unsuitable solvents include water, methanol, or ethanol.

5. The method for preparing a non-close-packed rainbow superlattice two-dimensional thin film according to claim 1, characterized in that, The molecular weight of polystyrene-polyacrylic acid is 17,000-21,000.

6. The method for preparing a non-close-packed rainbow superlattice two-dimensional thin film according to claim 1, characterized in that, The heating conditions are 90-110 ℃ for 50-60 min.

7. The method for preparing a non-close-packed rainbow superlattice two-dimensional thin film according to claim 1, characterized in that, In an anhydrous ethanol / n-hexane solution of perfluorodecylthiol, the concentration of perfluorodecylthiol is 8-12 mM, and the volume ratio of anhydrous ethanol to n-hexane is 1-3:

1.

8. The non-close-packed rainbow superlattice two-dimensional thin film prepared by the preparation method of any one of claims 1-7.

9. The non-close-packed rainbow superlattice two-dimensional thin film according to claim 8, characterized in that, The colors of non-close-packed rainbow superlattice two-dimensional thin films include pink, brown, purple, blue, green, or yellow.

10. The application of the non-close-packed rainbow superlattice two-dimensional thin film according to claim 8 in the fields of display, sensing or anti-counterfeiting.

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