Preparation method and anti-counterfeiting application of quantum dot glass etched by femtosecond laser

Abstract

The invention discloses a femtosecond laser etched quantum dot glass preparation method and anti-counterfeiting application, and belongs to the technical field of quantum dot luminescent materials and laser micromachining. According to the glass material, precursor glass is prepared through a melting quenching method, then femtosecond laser direct writing etching and subsequent heat treatment are conducted, femtosecond laser is used for etching the glass, and a high-resolution patterned light-emitting structure can be achieved on the surface of the glass. After fluorescence quenching of the pattern in an air environment, fluorescence recovery can be achieved through low-temperature annealing (300 DEG C), and the reversible encryption-decryption function is achieved. The perovskite quantum dot solves the problems of poor environmental stability and difficult patterning processing of the traditional perovskite quantum dot, and is suitable for the fields of optical storage, anti-counterfeiting marks, reconfigurable photoelectric devices and the like.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials and laser micromachining technology, specifically relating to a method for preparing quantum dot glass, a femtosecond laser etching process, and its application in optical encryption. Background Technology

[0002] Perovskite cesium lead halide (CsPbX3) nanocrystals (NCs) possess advantages such as tunable quantum size, narrow emission peaks, and full coverage of the visible light region, making them potentially valuable in numerous fields including bioimaging, photocatalysis, lighting, diagnostics, displays, solar cells, lasers, and photodetectors. The commercialization of this material is being actively pursued, particularly in lighting and display applications. However, the instability of CsPbX3 nanocrystal solutions remains an obstacle to their practical application. Although many researchers have attempted to maintain their excellent optical properties by forming core-shell structures through polymer encapsulation, colloidal CsPbX3 perovskite nanocrystals prepared by traditional hot-injection methods still suffer from air corrosion and thermal instability. A robust glass network structure not only isolates the fluorescent quantum dots from the external environment but also reduces the Pb content. 2+ Toxin leakage.

[0003] Although existing studies have encapsulated quantum dots in glass to improve stability, achieving precise structural control within glass and endowing it with reversible optical response remains a technical challenge. For example, CN117069377A discloses a method for encapsulating perovskite quantum dots in glass, but it requires high-temperature heat treatment above 530 °C and cannot achieve patterning. To solve the problem of precise control of quantum dot glass structure, researchers at home and abroad have conducted extensive research. However, traditional preparation methods are difficult to achieve precise control of the micro-nano structure of quantum dot glass, and existing technologies have not yet achieved: (1) femtosecond laser-induced local in-situ crystallization of quantum dots in glass; (2) reversible fluorescent switch based on air exposure-low temperature annealing. Summary of the Invention

[0004] The purpose of this invention is to address the technical problems of precise patterning and lack of reversible optical response in existing perovskite quantum dots (CsPbX3). This invention provides a femtosecond laser-etched quantum dot glass and its preparation method, which enables precise patterned distribution of quantum dots and possesses reversible "encryption-decryption" functionality. The core technical solution of this invention includes: preparing a homogeneous, crystal-free precursor glass through specific component design (including Cs, Pb, Br, Yb, etc.); utilizing the ultrafast nonlinear effect of the femtosecond laser at the focal point to induce in-situ crystallization of perovskite quantum dots (CsPbBr3) in the glass network, achieving patterning and functional region customization of the material surface; utilizing the effect of the air environment on the quantum dot surface to achieve fluorescence quenching (encryption), and achieving fluorescence recovery (decryption) by repairing defects through low-temperature annealing.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: (1) Weigh the required raw materials separately, with the following masses: 0.8g Na2CO3, 0.4g BaCO3, 1.67g ZnO, 4.95g H3BO3, 1.62g SiO2, 0.54g Cs2CO3, 0.68g Pb3O4, 0.8g NaBr, and 0.4g Yb2O3. Then, place the weighed glass raw materials, fluorescent material raw materials, and rare earth oxides into a mortar and mix thoroughly, then grind to obtain a fluorescent glass mixture. (2) Pour the above fluorescent glass mixture into a corundum crucible, place it in a muffle furnace at a temperature of 1050 ℃ and sinter at a constant temperature for 10 minutes, then pour the melt into a preheated mold at 400 ℃ to obtain the precursor glass. (3) Polish the obtained precursor glass with polishing paste in a polishing machine, and clean the polished sample in ethanol and water in turn to thoroughly remove surface contaminants. (4) Fix the polished precursor glass sample onto the motion platform; (5) Turn on the femtosecond laser with a center wavelength of 1030 nm and set the laser parameters: laser power of 100–350 mW, repetition frequency of 25 kHz, pulse width of 0.3 ps, motor scanning speed of 0.08 mm / s, and adjust the optical path. (6) Open the motor control software on the computer, control the sample placement position, use the CCD camera to image, and after accurately adjusting the laser focus to the sample surface, remove the beam blocker to perform laser etching. (7) Place the etched quantum dot glass in an air environment for 3 days, and after the quantum dots are quenched, place it in a muffle furnace at 300 °C and keep it warm for 10 h.

[0006] Beneficial effects 1. Achieving precise, arbitrary, and controllable spatial distribution of quantum dots. This invention applies femtosecond laser direct writing technology to a glass system with a specific composition. Utilizing the extremely high peak power at the laser focal point to induce local nonlinear effects, quantum dots are generated in situ within the scanning area. By controlling the scanning path with a computer, arbitrarily designed micro / nano fluorescent patterns (such as QR codes, microarrays, and complex curves) can be precisely "drawn" inside or on the surface of the glass, laying the technological foundation for the direct application of quantum dots in integrated photonic chips, high-density optical storage, and microdisplays. 2. This invention endows glass with unique "air-sensitive-thermal-recovery" dynamic fluorescence properties, constructing a reversible optical encryption platform. The patterned quantum dot glass prepared in this invention exhibits a smart response behavior: (a) Initial state: The laser-etched area emits bright green fluorescence under ultraviolet light (365 nm) excitation, forming visible encrypted information. (b) Encrypted state: When the pattern is exposed to air for 1-3 days, the fluorescence is gradually and completely quenched due to surface oxidation or humidity, thus hiding the information. (c) Decrypted state: Traditional heat treatment methods require annealing at 450 °C. This invention uses a simple 300 °C low-temperature annealing treatment for 10 h, which completely recovers the quenched fluorescence, reproducing the information and reducing energy consumption. This reversible fluorescence switching effect based on environmental exposure and low-temperature heat treatment provides a novel carrier for achieving high-level dynamic optical information encryption and anti-counterfeiting. Attached Figure Description

[0007] This invention includes four accompanying figures illustrating the preparation process and optical properties of quantum dot glass.

[0008] Figure 1 Luminescence photographs and photoluminescence spectra of quantum dot glasses prepared under different laser powers in Examples 1, 2, 3, 4, and 5; Figure 2 The images show the luminescence of quantum dot glass obtained by different laser power etching in Examples 1, 2, 3, 4, and 5 after being placed in air for 3 days, under 365 nm ultraviolet light excitation. Figure 3 The image shows a comparison of the photoluminescence spectra of the quantum dot glass prepared in Example 1 after laser etching, after being quenched in air for three days, and after annealing at 300 °C for 10 h.

[0009] Figure 4 shows the luminescence photograph and photoluminescence spectrum of the quantum dot glass prepared in Comparative Example 1 after annealing at 450 °C for 10 h. Detailed Implementation

[0010] To better understand the objectives, technical solutions, and advantages of this invention, the above technical solutions will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and do not constitute any limitation on the scope of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0011] Example 1 Analytical-grade Na₂CO₃, BaCO₃, ZnO, H₃BO₃, SiO₂, Cs₂CO₃, Pb₃O₄, NaBr, and Yb₂O₃ were weighed in the following proportions: 0.8g Na₂CO₃, 0.4g BaCO₃, 1.67g ZnO, 4.95g H₃BO₃, 1.62g SiO₂, 0.54g Cs₂CO₃, 0.68g Pb₃O₄, 0.8g NaBr, and 0.4g Yb₂O₃. The weighed raw materials were poured into an agate grinding pan and thoroughly mixed. Then, the mixture was ground for 15 minutes until homogeneous. The thoroughly ground raw materials were transferred from the agate grinding pan to a 50 mL corundum crucible, and then the corundum crucible containing the raw materials was placed in a muffle furnace at 1050 °C for high-temperature sintering for 10 minutes. The sintered precursor glass was poured onto a heating platform containing a copper mold plate at a temperature of 400 °C. The heating platform temperature was maintained for 3 hours to eliminate internal stress, and then the glass was allowed to cool naturally to room temperature. The precursor glass was then polished with polishing compound on a polishing machine. The polished sample was then washed with ethanol and water in sequence to thoroughly remove surface contaminants, thus obtaining the unannealed perovskite quantum dot precursor glass sample.

[0012] Turn on the femtosecond laser with a center wavelength of 1030 nm and set the laser parameters as follows: laser power of 100 mW, repetition frequency of 25 kHz, pulse width of 0.3 ps, and scanning speed of 0.08 mm / s. Adjust the optical path and release the laser after preheating. Fix the polished precursor glass sample on the motion platform, ensuring that its surface is parallel to the laser beam scanning plane. Turn on the computer and use the CCD camera to image the sample. After accurately adjusting the laser focus to the sample surface, remove the beam blocker and perform laser etching. Place the etched quantum dot glass slide in an air environment with room temperature (25±2℃) and relative humidity of 50-70% for 3 days. After the quantum dots are quenched, place it in a muffle furnace at 300 ℃ for 10 h.

[0013] Performance testing: The optical properties of the quantum dot materials prepared in Example 1 were tested using an FX4000 rapid spectrometer, such as... Figure 1 As shown, under 365 nm excitation light, it exhibits bright green emission with an independent emission peak at 509 nm. After being placed in air for 3 days, the quantum dots gradually quenched. Figure 2 As shown, it was finally placed in a muffle furnace at 300 ℃ and kept at that temperature for 10 h to perform optical performance tests, such as... Figure 3 As shown, it exhibits bright green emission under 365 nm excitation light, and the emission spectrum shows an independent emission peak located at 512 nm.

[0014] Example 2 Analytical-grade Na₂CO₃, BaCO₃, ZnO, H₃BO₃, SiO₂, Cs₂CO₃, Pb₃O₄, NaBr, and Yb₂O₃ were weighed in the following proportions: 0.8g Na₂CO₃, 0.4g BaCO₃, 1.67g ZnO, 4.95g H₃BO₃, 1.62g SiO₂, 0.54g Cs₂CO₃, 0.68g Pb₃O₄, 0.8g NaBr, and 0.4g Yb₂O₃. The weighed raw materials were poured into an agate grinding pan and thoroughly mixed. Then, the mixture was ground for 15 minutes until homogeneous. The thoroughly ground raw materials were transferred from the agate grinding pan to a 50 mL corundum crucible, and then the corundum crucible containing the raw materials was placed in a muffle furnace at 1050 °C for high-temperature sintering for 10 minutes. The sintered precursor glass was poured onto a heating platform containing a copper mold plate at a temperature of 400°C. The heating platform temperature was maintained for 3 hours to eliminate internal stress, and then the glass was allowed to cool naturally to room temperature. The resulting precursor glass was then polished with polishing compound on a polishing machine. The polished sample was then washed in ethanol and water in sequence to thoroughly remove surface contaminants, thus obtaining the unannealed perovskite quantum dot precursor glass sample.

[0015] Turn on the femtosecond laser with a center wavelength of 1030 nm and set the laser parameters as follows: laser power of 150 mW, repetition frequency of 25 kHz, pulse width of 0.3 ps, and scanning speed of 0.08 mm / s. Adjust the optical path and release the laser after it has preheated. Fix the polished precursor glass sample on the motion platform, ensuring that its surface is parallel to the laser beam scanning plane. Turn on the computer and use the CCD camera to image the sample. After the laser focus is precisely adjusted to the sample surface, remove the beam blocker to perform laser etching. Place the etched quantum dot glass sheet in an air environment with room temperature (25±2℃) and relative humidity of 50-70% for 3 days. Example 2 only shows the "encryption" process.

[0016] Performance testing: The optical properties of the quantum dot materials prepared in Example 2 were tested using an FX4000 rapid spectrometer, such as... Figure 1 As shown, under 365 nm excitation light, it exhibits bright green emission with an independent emission peak at 509 nm. After being placed in air for 3 days, the quantum dots gradually quenched. Figure 2 As shown.

[0017] Example 3 Analytical-grade Na₂CO₃, BaCO₃, ZnO, H₃BO₃, SiO₂, Cs₂CO₃, Pb₃O₄, NaBr, and Yb₂O₃ were weighed in the following proportions: 0.8g Na₂CO₃, 0.4g BaCO₃, 1.67g ZnO, 4.95g H₃BO₃, 1.62g SiO₂, 0.54g Cs₂CO₃, 0.68g Pb₃O₄, 0.8g NaBr, and 0.4g Yb₂O₃. The weighed raw materials were poured into an agate grinding pan and thoroughly mixed. Then, the mixture was ground for 15 minutes until homogeneous. The thoroughly ground raw materials were transferred from the agate grinding pan to a 50 mL corundum crucible, and then the corundum crucible containing the raw materials was placed in a muffle furnace at 1050 °C for high-temperature sintering for 10 minutes. The sintered precursor glass was poured onto a heating platform containing a copper mold plate at a temperature of 400°C. The heating platform temperature was maintained for 3 hours to eliminate internal stress, and then the glass was allowed to cool naturally to room temperature. The resulting precursor glass was then polished with polishing compound on a polishing machine. The polished sample was then washed in ethanol and water in sequence to thoroughly remove surface contaminants, thus obtaining the unannealed perovskite quantum dot precursor glass sample.

[0018] Turn on the femtosecond laser with a center wavelength of 1030 nm and set the laser parameters as follows: laser power of 200 mW, repetition frequency of 25 kHz, pulse width of 0.3 ps, and scanning speed of 0.08 mm / s. Adjust the optical path and release the laser after it has preheated. Fix the polished precursor glass sample on the motion platform, ensuring that its surface is parallel to the laser beam scanning plane. Turn on the computer and use the CCD camera to image the sample. After the laser focus is precisely adjusted to the sample surface, remove the beam blocker to perform laser etching. Place the etched quantum dot glass sheet in an air environment with room temperature (25±2℃) and relative humidity of 50-70% for 3 days. Example 3 only shows the "encryption" process.

[0019] Performance testing: The optical properties of the quantum dot materials prepared in Example 3 were tested using an FX4000 rapid spectrometer, such as... Figure 1 As shown, under 365 nm excitation light, it exhibits bright green emission with an independent emission peak at 516 nm. After being placed in air for 3 days, the quantum dots gradually quenched. Figure 2 As shown.

[0020] Example 4 Analytical-grade Na₂CO₃, BaCO₃, ZnO, H₃BO₃, SiO₂, Cs₂CO₃, Pb₃O₄, NaBr, and Yb₂O₃ were weighed in the following proportions: 0.8g Na₂CO₃, 0.4g BaCO₃, 1.67g ZnO, 4.95g H₃BO₃, 1.62g SiO₂, 0.54g Cs₂CO₃, 0.68g Pb₃O₄, 0.8g NaBr, and 0.4g Yb₂O₃. The weighed raw materials were poured into an agate grinding pan and thoroughly mixed. Then, the mixture was ground for 15 minutes until homogeneous. The thoroughly ground raw materials were transferred from the agate grinding pan to a 50 mL corundum crucible. The corundum crucible containing the raw materials was then placed in a muffle furnace at 1050℃ for high-temperature sintering for 10 minutes. The sintered precursor glass was poured onto a heating platform containing a copper mold plate at a temperature of 400°C. The heating platform temperature was maintained for 3 hours to eliminate internal stress, and then the glass was allowed to cool naturally to room temperature. The resulting precursor glass was then polished with polishing compound on a polishing machine. The polished sample was then washed in ethanol and water in sequence to thoroughly remove surface contaminants, thus obtaining the unannealed perovskite quantum dot precursor glass sample.

[0021] Turn on the femtosecond laser with a center wavelength of 1030 nm and set the laser parameters as follows: laser power of 300 mW, repetition frequency of 25 kHz, pulse width of 0.3 ps, and scanning speed of 0.08 mm / s. Adjust the optical path and release the laser after it has preheated. Fix the polished precursor glass sample on the motion platform, ensuring that its surface is parallel to the laser beam scanning plane. Turn on the computer and use the CCD camera to image the sample. After the laser focus is precisely adjusted to the sample surface, remove the beam blocker to perform laser etching. Place the etched quantum dot glass sheet in an air environment with room temperature (25±2℃) and relative humidity of 50-70% for 3 days. Example 4 only shows the "encryption" process.

[0022] Performance testing: The optical properties of the quantum dot materials prepared in Example 4 were tested using an FX4000 rapid spectrometer, such as... Figure 1 As shown, under 365 nm excitation light, it exhibits bright green emission with an independent emission peak at 516 nm. After being placed in air for 3 days, the quantum dots gradually quenched. Figure 2 As shown.

[0023] Example 5 Analytical-grade Na₂CO₃, BaCO₃, ZnO, H₃BO₃, SiO₂, Cs₂CO₃, Pb₃O₄, NaBr, and Yb₂O₃ were weighed in the following proportions: 0.8g Na₂CO₃, 0.4g BaCO₃, 1.67g ZnO, 4.95g H₃BO₃, 1.62g SiO₂, 0.54g Cs₂CO₃, 0.68g Pb₃O₄, 0.8g NaBr, and 0.4g Yb₂O₃. The weighed raw materials were poured into an agate grinding pan and thoroughly mixed. Then, the mixture was ground for 15 minutes until homogeneous. The thoroughly ground raw materials were transferred from the agate grinding pan to a 50 mL corundum crucible, and then the corundum crucible containing the raw materials was placed in a muffle furnace at 1050 °C for high-temperature sintering for 10 minutes. The sintered precursor glass was poured onto a heating platform containing a copper mold plate at a temperature of 400 °C. The heating platform temperature was maintained for 3 hours to eliminate internal stress, and then the glass was allowed to cool naturally to room temperature. The precursor glass was then polished with polishing compound on a polishing machine. The polished sample was then washed with ethanol and water in sequence to thoroughly remove surface contaminants, thus obtaining the unannealed perovskite quantum dot precursor glass sample.

[0024] Turn on the femtosecond laser with a center wavelength of 1030 nm and set the laser parameters as follows: laser power of 350 mW, repetition frequency of 25 kHz, pulse width of 0.3 ps, and scanning speed of 0.08 mm / s. Adjust the optical path and release the laser after it has preheated. Fix the polished precursor glass sample on the motion platform, ensuring that its surface is parallel to the laser beam scanning plane. Turn on the computer and use the CCD camera to image the sample. After the laser focus is precisely adjusted to the sample surface, remove the beam blocker to perform laser etching. Place the etched quantum dot glass sheet in an air environment with room temperature (25±2℃) and relative humidity of 50-70% for 3 days. Example 5 only shows the "encryption" process.

[0025] Performance testing: The optical properties of the quantum dot materials prepared in Example 5 were tested using an FX4000 rapid spectrometer, such as... Figure 1 As shown, under 365 nm excitation light, it exhibits bright green emission with an independent emission peak at 518 nm. After being placed in air for 3 days, the quantum dots gradually quenched. Figure 2 As shown.

[0026] Comparative Example 1 Analytical-grade Na₂CO₃, BaCO₃, ZnO, H₃BO₃, SiO₂, Cs₂CO₃, Pb₃O₄, NaBr, and Yb₂O₃ were weighed according to the following mass values: 0.8 g Na₂CO₃, 0.4 g BaCO₃, 1.67 g ZnO, 4.95 g H₃BO₃, 1.62 g SiO₂, 0.54 g Cs₂CO₃, 0.68 g Pb₃O₄, 0.8 g NaBr, and 0.4 g Yb₂O₃. The weighed raw materials were poured into an agate grinding pan and thoroughly mixed. Then, the mixture was ground for 15 minutes until homogeneous. The thoroughly ground raw materials were transferred from the agate grinding pan to a 50 mL corundum crucible, and then the corundum crucible containing the raw materials was placed in a muffle furnace at 1050℃ for high-temperature sintering for 10 minutes. The sintered precursor glass was poured onto a heating platform containing a copper mold plate at 400°C. The heating platform temperature was maintained for 3 hours to eliminate internal stress, followed by natural cooling to room temperature. The resulting precursor glass was then polished using polishing compound on a polishing machine. The polished sample was then washed sequentially with ethanol and water to thoroughly remove surface contaminants, yielding the unannealed perovskite quantum dot precursor glass sample. The obtained precursor glass was then placed in a muffle furnace at 450°C and held for 10 hours.

[0027] Performance testing: The optical properties of the quantum dot material prepared in Comparative Example 1 were tested using an FX4000 rapid spectrometer, such as... Figure 4 As shown, under 365 nm excitation, the entire glass block exhibits uniform green fluorescence with a peak at 525 nm, making patterning impossible.

[0028] Conclusion: Comparative Example 1 demonstrates that femtosecond laser etching is key to achieving patterning and reversible fluorescence modulation. The experimental results of the five sets of examples above show that femtosecond laser direct writing technology can directly induce in-situ crystallization of quantum dots in untreated precursor glass, producing a clear green fluorescent pattern immediately after etching, avoiding the shortcomings of traditional methods that require overall annealing. As the laser power increases from 100 mW to 350 mW, the photoluminescence (PL) intensity shows a monotonically increasing trend, indicating that increasing the laser power can effectively promote the nucleation and crystallization of more quantum dots. In Example 1, the pattern underwent significant quenching after 3 days of exposure to air, such as... Figure 2 As shown. Notably, annealing the quenched sample at 300°C for 10 hours significantly restored its fluorescence intensity, as shown... Figure 3 As shown in the figure, this "laser-induced nucleation-low-temperature annealing stabilization" strategy not only reduces energy consumption but also provides a new approach to achieving "reversible encryption-decryption" of optical information, demonstrating significant application potential in the fields of advanced anti-counterfeiting and secure storage.

Claims

1. A method for preparing quantum dot glass etched by femtosecond laser, characterized in that, Includes the following steps: (1) Weigh the raw materials, then put the weighed raw materials into a mortar and mix them thoroughly, and grind them to obtain a mixture; (2) Pour the above mixture into a crucible, place it in a muffle furnace for sintering, pour the melt into a preheated mold, and then slowly cool it to room temperature to obtain a transparent, crack-free precursor glass block. (3) Polish the obtained precursor glass with polishing paste, and clean the polished sample in ethanol and water in sequence. (4) Fix the polished precursor glass sample onto the motion platform; (5) Turn on the femtosecond laser, set the laser parameters, including laser repetition frequency, laser power, etc., and adjust the optical path; (6) Open the motor control software on the computer, control the sample placement position, and use the CCD camera to precisely adjust the laser focus to the sample surface before laser etching. (7) Place the etched quantum dot glass in an air environment for 3 days, and after the quantum dots are quenched, place it in a muffle furnace at 300 °C and keep it warm for 10 h.

2. The method according to claim 1, characterized in that, The raw materials and their quantities are: 0.8g Na2CO3, 0.4g BaCO3, 1.67g ZnO, 4.95g H3BO3, 1.62g SiO2, 0.54g Cs2CO3, 0.68g Pb3O4, 0.8g NaBr, and 0.4g Yb2O3.

3. The method according to claim 1, characterized in that, The sintering temperature in step (2) is 1050 °C and the time is 10 minutes.

4. The method according to claim 1, characterized in that, The temperature of the preheated mold in step (2) is 350-400℃, and the holding time is 3 hours.

5. The method according to claim 1, characterized in that, The center wavelength of the femtosecond laser in step (5) is 1030 nm.

6. The method according to claim 1, characterized in that, The laser parameters in step (5) are: laser power of 100–350 mW, repetition frequency of 25 kHz, pulse width of 0.3 ps, and motor scanning speed of 0.08 mm / s.

7. The method according to claim 1, characterized in that, The air environment described in step (7) is natural air with room temperature and relative humidity of 50-70%.

8. A femtosecond laser-etched quantum dot glass prepared by the method according to any one of claims 1-7, characterized in that: (1) The glass substrate is a borosilicate glass containing Cs, Pb, Br and Yb; (2) A patterned CsPbBr3 quantum dot luminescent region is formed on the glass surface by femtosecond laser etching; (3) The pattern emits green fluorescence under 365 nm ultraviolet light excitation, with the emission peak located at 509-518 nm.

9. The application of quantum dot glass in optical encryption according to claim 8, characterized in that: (1) The pattern emits green fluorescence under 365 nm ultraviolet light excitation, forming visible information; (2) Fluorescence quenching is achieved by exposing the device to air for 1-3 days, thus completing the information encryption; (3) Fluorescence recovery was achieved by annealing at 300 ℃ for 10 h, thus completing the information decryption.

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