Stimuli-responsive dual-mode luminescent silicon nanodots, polymer films and their applications in information encryption

Abstract

The application discloses a kind of stimulus response bimodal afterglow silicon nanodots, polymer film and its application in information encryption, the silicon nanodot is prepared by hydrothermal reaction by citric acid, levofloxacin and (3-amino propyl) trimethoxysilane as raw material.This stimulus response bimodal afterglow silicon nanodot of the application is successfully reduced to 0.42 eV by introducing high electronegativity C-F and Si-F bond ΔE ST F-SiNDs, so that it has the thermal discoloration afterglow characteristic from yellow green to blue, realizes the synergistic effect of room temperature phosphorescence and thermal activated delayed fluorescence.The application integrates the same luminescent core F-SiNDs into PVA and PVC matrix respectively, and gives the material different environmental response ability;based on the reconstruction of dynamic hydrogen bond network in PVA film, reversible "on-off" response to water and heat stimulation is realized, and has extremely excellent water-soluble recasting film recycling performance.

Description

Technical Field

[0001] This invention relates to the intersection of nanoluminescent materials and information security, and particularly to a stimulus-responsive dual-mode afterglow silicon nanodot, a polymer film, and their application in information encryption. Background Technology

[0002] Room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) materials, based on their long lifetime and high signal-to-noise ratio, show great potential in fields such as information encryption, flexible displays, and bioimaging. However, many high-performance luminescent systems rely on structurally complex organic light emitters or heavy metal complexes. The synthesis processes of these traditional materials are cumbersome and costly to scale up, conflicting with the demands for flexible, large-area, and sustainable applications. Silicon nanodots (SiNDs), due to their low toxicity, excellent biocompatibility, tunable surface chemistry, and ease of large-scale fabrication, hold great promise in sensing, imaging, and anti-counterfeiting. However, existing research on SiNDs mainly focuses on fluorescence (FL) or single room-temperature phosphorescence behavior. Systematic studies on simultaneously achieving dual-mode afterglow of RTP and TADF within a single silicon nanoluminescent center through fine energy level engineering remain scarce. Furthermore, research on integrating fluorinated silicon nanodots into flexible devices exhibiting both dual-mode emission and multiple stimulus responses is even rarer. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a stimulus-responsive dual-mode afterglow silicon nanodot, polymer film and its application in information encryption.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: In the first aspect of the present invention, a stimulus-responsive bimodal afterglow silicon nanodot is provided, which is prepared by hydrothermal reaction using citric acid, levofloxacin and (3-aminopropyl)trimethoxysilane as raw materials.

[0005] Preferably, the stimulus-responsive dual-mode afterglow silicon nanodots are prepared by the following steps: Citric acid, levofloxacin, and (3-aminopropyl)trimethoxysilane were added to deionized water and stirred until homogeneous. The resulting mixture was subjected to a hydrothermal reaction at 130-170°C for 2-8 hours. After the reaction was completed, the mixture was cooled and ground to obtain the stimulus-responsive bimodal afterglow silicon nanodots. Preferably, the stimulus-responsive dual-mode afterglow silicon nanodots are prepared by the following steps: Add 0.5-2g citric acid, 0.05-0.2g levofloxacin and 0.5-2mL (3-aminopropyl)trimethoxysilane to 10-40mL deionized water, stir until homogeneous, and allow the resulting mixture to undergo a hydrothermal reaction at 130-170℃ for 2-8 hours in an open environment. After the reaction is complete, cool to room temperature and grind into powder to obtain the stimulus-responsive bimodal afterglow silicon nanodots.

[0006] Preferably, the stimulus-responsive dual-mode afterglow silicon nanodots are prepared by the following steps: 1.0 g citric acid, 0.1 g levofloxacin and 1.0 mL (3-aminopropyl)trimethoxysilane were added to 20.0 mL deionized water and stirred until homogeneous. The resulting mixture was placed in a beaker and heated open at 150 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature and the solid product was ground into powder to obtain the stimulus-responsive bimodal afterglow silicon nanodots.

[0007] A second aspect of the present invention provides the application of silicon nanodots as described above in information encryption.

[0008] A third aspect of the present invention provides a stimulus-responsive flexible polymer composite film (denoted as F-SiNDs@PVA film), which is prepared by doping silicon nanodots as described above into polyvinyl alcohol.

[0009] Preferably, the stimulus-responsive flexible polymer composite film is prepared by the following method: The silicon nanodots and polyvinyl alcohol described above were added to deionized water, heated and stirred, and the resulting mixture was coated onto a substrate. After drying, the mixture was peeled off to obtain the stimulus-responsive flexible polymer composite film.

[0010] Preferably, the stimulus-responsive flexible polymer composite film is prepared by the following method: Add 2.5-10 mg of silicon nanodots as described above and 0.25-1 g of PVA to 5-20 mL of deionized water, stir at 40-80 °C for 15-60 minutes, coat the resulting mixture onto a substrate, dry at 40-80 °C for 5-20 hours, and peel off to obtain the stimulus-responsive flexible polymer composite film.

[0011] In a fourth aspect, the present invention provides another stimulus-responsive flexible polymer composite film (denoted as F-SiNDs@PVC film), which is prepared by doping polyvinyl chloride with silicon nanodots as described above.

[0012] Preferably, the stimulus-responsive flexible polymer composite film is prepared by the following method: The silicon nanodots and polyvinyl chloride described above were added to an N,N-dimethylacetamide solution, heated and stirred, and the resulting mixture was coated onto a substrate. After drying, the mixture was peeled off to obtain the stimulus-responsive flexible polymer composite film.

[0013] Preferably, the stimulus-responsive flexible polymer composite film is prepared by the following method: Add 2.5-10 mg of silicon nanodots as described above and 0.25-1 g of polyvinyl chloride to 5-20 mL of N,N-dimethylacetamide solution, stir at 40-80 °C for 15-60 minutes, coat the resulting mixture onto a substrate, dry at 40-80 °C for 5-20 hours, and peel off to obtain the stimulus-responsive flexible polymer composite film.

[0014] A fifth aspect of the present invention provides the application of F-SiNDs@PVA film or F-SiNDs@PVC film in information encryption.

[0015] A sixth aspect of the present invention provides the application of a combination of F-SiNDs@PVA film and F-SiNDs@PVC film in information encryption.

[0016] The beneficial effects of this invention are: 1. Excellent optical performance and dual-mode luminescence: The stimulus-responsive dual-mode afterglow silicon nanodots (F-SiNDs) of this invention successfully enhance the ΔE of F-SiNDs by introducing highly electronegative CF and Si-F bonds. ST The voltage was reduced to 0.42 eV, giving it thermochromic afterglow characteristics from yellow-green to blue, achieving a synergistic effect of room temperature phosphorescence and thermally activated delayed fluorescence.

[0017] 2. Green and economical preparation process: This invention uses low-toxicity citric acid, silane and levofloxacin as precursors and synthesizes them through a simple hydrothermal method. It does not require the use of heavy metals or complex organic synthesis routes. The process is not only environmentally friendly and low-cost, but also very easy to mass-produce.

[0018] 3. Intelligent dynamic response and recyclability: This invention integrates the same light-emitting core F-SiNDs into PVA and PVC matrices respectively, giving the materials differentiated environmental response capabilities; based on the reconstruction of the dynamic hydrogen bond network in the PVA film, it realizes a reversible "on-off" response to water and heat stimulation, and has extremely excellent water-soluble recast membrane recycling performance.

[0019] 4. Advanced Information Encryption Applications: This invention combines the unique matrix-dependent response of thin films (F-SiNDs@PVA films are quenched when exposed to water, while F-SiNDs@PVC films retain luminescence) to successfully construct a reversible information encryption and decryption platform that can be operated in multiple cycles on a single device platform, providing an innovative solution for next-generation intelligent information anti-counterfeiting. Attached Figure Description

[0020] Figure 1 Characterization results of fluorine-doped silicon nanodots (F-SiNDs) and silicon nanodots (SiNDs) prepared in Example 1; Figure 2 The optical properties and mechanism of action of the SiNDs and F-SiNDs prepared in Example 1 are characterized. Figure 3 The results show the application performance test results of the F-SiNDs prepared in Example 1. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0023] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0024] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available. For examples where specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer are followed. For reagents or instruments whose manufacturers are not specified, they are all commercially available products.

[0025] This invention uses levofloxacin as a fluorine source to prepare fluorine-doped silicon nanodots (F-SiNDs) via a simple hydrothermal method. By introducing highly electronegative CF and Si-F bonds, the energy level structure is fine-tuned, reducing the singlet-to-triplet bandgap (ΔE). ST The effective reduction was reduced to 0.42 eV.

[0026] This extremely low bandgap enabled synergistic dual-mode afterglow emission of RTP and TADF within a single nanoluminescent center. Subsequently, F-SiNDs were embedded in hydrophilic polyvinyl alcohol (PVA) and hydrophobic polyvinyl chloride (PVC) matrices to construct two flexible polymer composite films with different environmental responses.

[0027] The above is the general concept of the present invention. Based on this, detailed embodiments and comparative examples are provided below to further illustrate the present invention.

[0028] Example 1 (1) Synthesis of silicon nanodots (SiNDs): 1.0 g of citric acid and 1.0 mL of (3-aminopropyl)trimethoxysilane (APTES) were added to 20.0 mL of deionized water and stirred until homogeneous. The resulting mixture was then placed in a beaker and heated open at 150 °C for 4 hours. After the reaction was complete, the solid product was cooled to room temperature and ground into powder.

[0029] (2) Synthesis of fluorine-doped silicon nanodots (F-SiNDs): 1.0 g citric acid, 0.1 g levofloxacin, and 1.0 mL APTES were added to 20.0 mL deionized water and stirred until homogeneous. The mixture was then placed in a beaker and heated open at 150 °C for 4 hours. After the reaction was complete, the solid product was cooled to room temperature and ground into powder to obtain fluorine-doped silicon nanodots (F-SiNDs), i.e., stimulus-responsive bimodal afterglow silicon nanodots.

[0030] (3) Synthesis of F-SiNDs@PVA thin films: 5.0 mg F-SiNDs powder and 0.5 g PVA (polyvinyl alcohol) were added to 10.0 mL of deionized water. The mixture was heated at 60 °C and stirred for 30 minutes until completely mixed. The resulting mixture was uniformly coated on the surface of a glass dish and dried in an oven at 60 °C for 10 hours. The film was then peeled off to obtain the stimulus-responsive flexible polymer composite film, denoted as F-SiNDs@PVA film.

[0031] (4) Synthesis of F-SiNDs@PVC film: 5.0 mg of F-SiNDs powder and 0.5 g of PVC were added to 10.0 mL of N,N-dimethylacetamide solution. The mixture was heated and stirred at 60 °C for 30 minutes until completely mixed. The resulting mixture was uniformly coated on the surface of a glass dish and dried in an oven at 60 °C for 10 hours. The film was then peeled off to obtain the stimulus-responsive flexible polymer composite film, denoted as F-SiNDs@PVC film.

[0032] Performance characterization and testing Reference Figure 1The figures show the characterization results of the fluorine-doped silicon nanodots (F-SiNDs) and silicon nanodots (SiNDs) prepared in Example 1, including: a) Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) images of F-SiNDs; b) Particle size distribution curves of F-SiNDs; c) X-ray diffraction (XRD) patterns of F-SiNDs and SiNDs; d) Fourier transform infrared (FT-IR) spectra of F-SiNDs and SiNDs; e) X-ray photoelectron spectroscopy (XPS) of F-SiNDs; and f) C1s energy spectrum of F-SiNDs.

[0033] Figure 1 ab shows that F-SiNd has a uniform particle size distribution and excellent colloidal dispersibility. X-ray diffraction patterns of SiNDs and F-SiNDs ( Figure 1 c) indicates that the typical structure of silicon nanodots is mainly disordered or partially crystalline. Fourier transform infrared spectroscopy (FTIR) Figure 1 d) It can be seen that it is located at 1207 cm -1 The characteristic CF stretching vibration at a certain point only appears in F-SiNDs, indicating successful fluorine doping. X-ray photoelectron spectroscopy confirmed that both samples contain four elements: Si, C, N, and O. The key difference in F-SiNDs is the presence of the characteristic peak F 1s, which further illustrates the successful incorporation of fluorine.

[0034] Reference Figure 2 The following are the characterization results of the optical properties and mechanisms of action of SiNDs and F-SiNDs prepared in Example 1, including: a) Phosphorescence spectra of SiNDs at temperatures ranging from 77 K to 393 K; b) Afterglow spectra of F-SiNDs at temperatures ranging from 77 K to 453 K; c) Lifetime decay curves of SiNDs and F-SiNDs at an emission wavelength of 545 nm; d) TADF lifetime of F-SiNDs at room temperature; e) RTP and TADF imaging of F-SiNDs under UV (365 nm) irradiation at different temperatures (298 K-398 K); f) RTP and TADF generation mechanisms in F-SiNDs.

[0035] It can be seen that as the temperature increases from 77 K to 393 K, the RTP intensity of SiNDs gradually decreases, and the maximum emission value exhibits a redshift. Figure 2 a), and the afterglow is completely extinguished as the temperature rises. However, the afterglow of F-SiNDs exhibits different changes with increasing temperature; its RTP intensity decreases, but the emission peak gradually blue-shifts (a). Figure 2 b). Combined with the temperature-dependent afterglow behavior, this indicates that the TADF of F-SiNDs becomes increasingly prominent at high temperatures. (Image of F-SiNDs) Figure 2 e) Visually confirms the smooth thermochromic evolution of the afterglow from yellowish-green to pale blue as temperature increases. For example... Figure 2 As shown in f, F doping increases the ΔE of F-SiNDs. ST Reduced to 0.42 eV, smaller ΔE ST This greatly facilitates the antisystem crossing process of excitons from T1 to S1, achieving efficient TADF and thus generating dual-mode afterglow.

[0036] Reference Figure 3 The figures show the application performance test results of the F-SiNDs prepared in Example 1, including: a) an image of a QR code generated using F-SiNDs ink; b) an image demonstrating TADF properties by adjusting the temperature in the nanodot film pattern; c) an image of the mechanism of the reversible water / thermal responsive RTP film; and d) a schematic diagram illustrating the principle of encrypting information by controlling phosphorescence switching in the RTP film through water / thermal stimulation.

[0037] This invention utilizes F-SiNDs to create functional ink QR codes ( Figure 3 a) The pattern is invisible under ambient light, but emits a bright yellow-green afterglow under 365 nm ultraviolet light. Heat treatment gradually triggers TADF, causing the afterglow to change from yellow-green to blue-green. Using pure water as ink, the letter information is directly engraved on F-SiNDs@PVA; under ultraviolet light, the characters become clearly visible due to the selective quenching effect of the water-exposed area; heating the film at 70°C for 30 minutes restores it to its original state, thus erasing the information. Figure 3 c). Furthermore, based on the different responses of the membrane to water quenching, a dual-stimulation information encryption system was constructed using F-SiNDs@PVA and F-SiNDs@PVC. Figure 3 d). When both are exposed to water vapor, only the afterglow of F-SiNDs@PVA is quenched, while the afterglow of F-SiNDs@PVC is retained, thus revealing the pre-designed encrypted information.

[0038] In summary, the F-SiNDs thin film developed in this invention possesses dual-mode RTP / TADF emission characteristics and can respond to environmental stimuli. These synergistic properties distinguish this invention from traditional single-mode RTP or TADF systems, enabling the establishment of a universal and sustainable platform for next-generation intelligent optical storage, dynamic anti-counterfeiting, and intelligent display devices.

[0039] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A stimulus-responsive dual-mode afterglow silicon nanodot, characterized in that, It is prepared by hydrothermal reaction using citric acid, levofloxacin and (3-aminopropyl)trimethoxysilane as raw materials.

2. The stimulus-responsive dual-mode afterglow silicon nanodots according to claim 1, characterized in that, It is prepared through the following steps: Citric acid, levofloxacin, and (3-aminopropyl)trimethoxysilane were added to deionized water and stirred until homogeneous. The resulting mixture was subjected to a hydrothermal reaction at 130-170°C for 2-8 hours. After the reaction was completed, the mixture was cooled and ground to obtain the stimulus-responsive bimodal afterglow silicon nanodots.

3. The stimulus-responsive dual-mode afterglow silicon nanodots according to claim 2, characterized in that, It is prepared through the following steps: Add 0.5-2g citric acid, 0.05-0.2g levofloxacin and 0.5-2mL (3-aminopropyl)trimethoxysilane to 10-40mL deionized water, stir until homogeneous, and allow the resulting mixture to undergo a hydrothermal reaction at 130-170℃ for 2-8 hours in an open environment. After the reaction is complete, cool to room temperature and grind into powder to obtain the stimulus-responsive bimodal afterglow silicon nanodots.

4. The stimulus-responsive dual-mode afterglow silicon nanodots according to claim 3, characterized in that, It is prepared through the following steps: 1.0 g citric acid, 0.1 g levofloxacin and 1.0 mL (3-aminopropyl)trimethoxysilane were added to 20.0 mL deionized water and stirred until homogeneous. The resulting mixture was placed in a beaker and heated open at 150 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature and the solid product was ground into powder to obtain the stimulus-responsive bimodal afterglow silicon nanodots.

5. The application of silicon nanodots as described in any one of claims 1-4 in information encryption.

6. A stimulus-responsive flexible polymer composite film, characterized in that, It is prepared by doping polyvinyl alcohol with silicon nanodots as described in any one of claims 1-4.

7. The stimulus-responsive flexible polymer composite film according to claim 6, characterized in that, It is prepared by the following method: The silicon nanodots and polyvinyl alcohol described in any one of claims 1-4 are added to deionized water, heated and stirred, and the resulting mixture is coated on a substrate, dried, and then peeled off to obtain the stimulus-responsive flexible polymer composite film.

8. The stimulus-responsive flexible polymer composite film according to claim 7, characterized in that, It is prepared by the following method: Add 2.5-10 mg of the silicon nanodots described in any one of claims 1-5 and 0.25-1 g of PVA to 5-20 mL of deionized water, stir at 40-80 °C for 15-60 minutes, coat the resulting mixture onto a substrate, dry at 40-80 °C for 5-20 hours, and peel off to obtain the stimulus-responsive flexible polymer composite film.

9. A stimulus-responsive flexible polymer composite film, characterized in that, It is prepared by doping polyvinyl chloride with silicon nanodots as described in any one of claims 1-4.

10. The stimulus-responsive flexible polymer composite film according to claim 9, characterized in that, It is prepared by the following method: The silicon nanodots and polyvinyl chloride described in any one of claims 1-4 are added to an N,N-dimethylacetamide solution, heated and stirred, and the resulting mixture is coated on a substrate, dried, and then peeled off to obtain the stimulus-responsive flexible polymer composite film.

11. The stimulus-responsive flexible polymer composite film according to claim 10, characterized in that, It is prepared by the following method: Add 2.5-10 mg of the silicon nanodots described in any one of claims 1-5 and 0.25-1 g of polyvinyl chloride to 5-20 mL of N,N-dimethylacetamide solution, stir at 40-80 °C for 15-60 minutes, coat the resulting mixture onto a substrate, dry at 40-80 °C for 5-20 hours, and peel off to obtain the stimulus-responsive flexible polymer composite film.

12. The application of the stimulus-responsive flexible polymer composite film as described in any one of claims 6-9 and / or any one of claims 9-11 in information encryption.

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