Method for realizing multi-state information anti-counterfeiting by stimulating color change of perovskite / polymer film through solvent and application

Abstract

The invention discloses a method for realizing multi-state information anti-counterfeiting by stimulating color change of a perovskite / polymer film through a solvent and application. Firstly, a CsPbX3-PVDF fluorescent thin film is prepared, when an acetone solvent acts on the CsPbX3-PVDF fluorescent thin film, the CsPbX3-PVDF fluorescent thin film can interact with PVDF and CsPbX3 crystals, perovskite crystal particles become small, under the quantum confinement effect, the fluorescence spectrum position of the CsPbX3-PVDF fluorescent thin film is subjected to blue shift, and the fluorescence spectrum of the CsPbX3-PVDF fluorescent thin film can be obtained by adjusting the acting time of the acetone solvent on the CsPbX3-PVDF fluorescent thin film and the mass fraction of PVDF in the polymer thin film. The size of the perovskite nanocrystal can be regulated and controlled, so that films with different blue shift degrees are obtained, and different fluorescence color changes are realized. Furthermore, by regulating and controlling the type of CsPbX3, various types of light-emitting changes can be obtained, so that multi-state response is realized, and the method is applied to high-order information encryption. The method provided by the invention is simple and good in stability, and can realize more convenient, low-cost and secure information encryption.

Description

Technical Field

[0001] The present invention relates to the field of preparation and color-changing encryption of perovskite thin-film luminescent materials, specifically to realizing the color change of perovskite / polymer thin films through solvent stimulation and realizing information encryption. Background Art

[0002] Technological revolutions such as artificial intelligence, big data, and quantum information have deeply influenced the industrial patterns of society and people's lifestyles. The rapid transmission of a large amount of information has made people's interactions more convenient, but at the same time, it also faces problems such as easy leakage and forgery of information. Especially for highly sensitive information, multi-layer encryption and decryption are required under specific conditions. Therefore, it is very important to develop information anti-counterfeiting and encryption materials that keep pace with technological development to further promote information protection. Fluorescent anti-counterfeiting has advantages such as high visibility, simple design, low manufacturing cost, and convenient verification, and the diversity of the spectrum provides multiple expressions for optical information storage and encryption.

[0003] Halide perovskite nanocrystals (PNCs) have tunable bandgaps, high photoluminescence quantum yields, and narrow emission linewidths. PNCs are easily affected by external environments such as light, heat, humidity, oxygen, and electric fields. At the same time, the controllability of the electronic dimension and diverse ion doping provide multi-state switchable luminescence behaviors, demonstrating the potential of PNCs in the field of information encryption. There are mainly two categories of methods to achieve multiple anti-counterfeiting with PNCs as the main body: the first category is multiple stimulus-responsive anti-counterfeiting, that is, on the basis of photoluminescence, other stimuli (such as light, heat, solvent, gas, etc.) are combined to present a multiple anti-counterfeiting effect of photoluminescence superposition color change. This method is mainly water-stimulus-responsive and realizes information encryption after the change of the phase structure. However, it is usually the conversion between single chromatograms and is only applicable to simple information anti-counterfeiting; the second category is multimodal luminescence anti-counterfeiting, mainly preparing single-component multimodal anti-counterfeiting materials. By doping ions on the selected matrix materials, the materials exhibit different photoluminescence characteristics under different light source excitations to achieve multiple anti-counterfeiting. This method can obtain more secure encryption, but the preparation process of multiple samples based on ion doping is difficult.

[0004] Therefore, it is very important to achieve the maximum modal response with the simplest and fewest variables to improve the information encryption density. In view of this, the present invention is proposed. Summary of the Invention

[0005] The present invention proposes a method for achieving multiplet response and completing high-order information encryption by using a single stimulus source to act on the same series of materials. That is, a CsPbX3-PVDF fluorescent film is prepared. When acetone solvent acts on it, it will interact with PVDF and CsPbX3 crystals, making the perovskite crystal particles smaller. Under the quantum confinement effect, the fluorescence spectrum position of the CsPbX3-PVDF film blue-shifts. By adjusting the time of acetone solvent acting on the CsPbX3-PVDF film, the mass fraction of PVDF in the polymer film, and the type of CsPbX3, various types of luminescence changes can be obtained, so as to achieve multiplet response and be applied to high-order information encryption. The preparation process of the present invention is simple and has good stability, so as to achieve more convenient, low-cost and secure information encryption.

[0006] In order to achieve the above object, the technical solution adopted in this application is as follows:

[0007] A method for achieving multiplet information anti-counterfeiting by solvent-stimulating the color change of perovskite / polymer film, and achieving multiplet information encryption by acetone-stimulating the fluorescence color change of perovskite / polymer film, including the following steps:

[0008] Step 1: Place polyvinylidene fluoride (PVDF), CsX (X = Br, I), PbX2 (X = Cl, Br, I) and N,N-dimethylformamide (DMF) in a sample bottle in a certain proportion, heat and stir on a stirrer until dissolved to obtain a lead halide perovskite precursor solution;

[0009] Step 2: Take a certain amount of the perovskite precursor solution obtained in Step 1 and spin-coat it on a glass slide to prepare a perovskite film;

[0010] Step 3: Heat the perovskite film obtained in Step 2 in an oven;

[0011] Step 4: Immerse the perovskite film heated in Step 3 into acetone solvent respectively, and soak for a certain time to obtain CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescent films;

[0012] Step 5: After arranging the CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescent films with different PVDF contents in Step 4, soak them in acetone for different times to obtain different color-changing patterns;

[0013] Step 6: Numerically encode the different color-changing patterns of the CsPbBrCl2, CsPbBr3, or CsPbI3 fluorescent films to obtain different digital combinations. Then, alphabetically encode the different digital combinations. Immerse the CsPbBrCl2, CsPbBr3, or CsPbI3 fluorescent films with different PVDF contents in acetone for a certain period of time, and decrypt the English words according to the obtained digital combinations and alphabetical encodings.

[0014] Step 7: Encode the different color-changing patterns of the CsPbBrCl2, CsPbBr3, or CsPbI3 fluorescent films, alphabetically encode the different digital combinations, and define their tones. Immerse the CsPbBrCl2, CsPbBr3, or CsPbI3 fluorescent films with different PVDF contents in acetone for a certain period of time, decrypt the Chinese characters according to the digital combinations, alphabetical encodings, and determination of tones, and combine them into complete sentences.

[0015] Furthermore: In Step 1, the mass ratio of the raw materials is polyvinylidene fluoride: total amount of (CsX, PbX2, N,N-dimethylformamide) in the precursor solution = 10%, 15%, 20%. The molar ratio of CsX to PbX2 is 1:1, and 1 mmol of CsX corresponds to 5 ml of DMF.

[0016] Furthermore, in Step 2, 1 ml of the perovskite precursor solution is taken, and the spinning time of the precursor is 30 s with a rotation speed of 4000 rpm.

[0017] Furthermore, in Step 3, the heating temperature is 80 °C and the time is 10 min.

[0018] Furthermore, in Step 4, the acetone soaking times are 0 min, 2 min, 4 min, 6 min, 8 min, and 10 min respectively.

[0019] Furthermore, in Step 5, the PVDF contents are 10%, 15%, and 20% respectively, and the soaking times are 0 min, 6 min, 10 min, 15 min, and 20 min respectively.

[0020] Furthermore, in Step 6, the PVDF contents are 10%, 15%, and 20% respectively, and the soaking time is 10 min.

[0021] Furthermore, in Step 7, the PVDF contents are 10%, 15%, and 20% respectively, and the soaking time is 10 min.

[0022] Furthermore, the present invention also provides the application of the solvent-stimulated perovskite / polymer film in the method of the present invention in the field of information encryption.

[0023] The advantages of the present invention compared with the prior art are as follows: by applying a stimulation source to a series of materials, multiple-state responses can be obtained in the present invention.

[0024] The technical effects of the present invention are as follows: a series of perovskite / polymer films are prepared by a simple method, and significant multiple fluorescence color changes will occur under the stimulation of acetone solvent. The films before and after color change have good stability, with no obvious luminescence decay after being placed in air for 100 days; and they also maintain a relatively high luminescence intensity after being soaked in an aqueous solution for 120 days.

[0025] Obviously, based on the above content of the present invention, according to the common general knowledge and customary means in the art, without departing from the above basic technical idea of the present invention, various other forms of modification, substitution or change can also be made. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the absorption spectrum diagram, fluorescence spectrum diagram, physical diagram of luminescence under ultraviolet light of CsPbI3 film soaked in acetone solvent for different times in Example 1 of the present invention, and the fluorescence spectrum diagram of films prepared with different concentrations of PVDF after being soaked in acetone for different times.

[0027] Figure 2 It is the transmission electron microscope (TEM) diagram of CsPbI3 films treated with acetone for 0 min, 6 min and 10 min obtained in Example 1.

[0028] Figure 3 It is the spectral change of CsPbI3 films treated with acetone for 0 min and 10 min obtained in Example 1 when placed in air for different times.

[0029] Figure 4 It is the change trend of the PL spectral intensity of CsPbI3 films treated with acetone for 0 min and 10 min obtained in Example 1 when soaked in water for different times and the physical diagram of luminescence under ultraviolet light.

[0030] Figure 5 It is the display diagram of information decryption under the stimulation of acetone in Example 1.

[0031] Figure 6 It is the display diagram of information decryption of digital combinations and letter definitions under the stimulation of acetone in Example 1.

[0032] Figure 7 It is the absorption spectrum diagram, fluorescence spectrum diagram, physical diagram of luminescence under ultraviolet light of CsPbBr3 film soaked in acetone solvent for different times in Example 2, and the fluorescence spectrum diagram of films prepared with different concentrations of PVDF after being soaked in acetone for different times.

[0033] Figure 8Absorption spectra, fluorescence spectra, physical pictures of the emission under ultraviolet light of CsPbBrCl2 thin films soaked in acetone solvent for different times in Example 3, and fluorescence spectra of thin films prepared with different concentrations of PVDF after being soaked in acetone for different times.

[0034] Figure 9 Schematic diagram of information decryption of three-dimensional color coding based on digital coding, letter combination and tone definition under the combination of Example 1, Example 2 and Example 3. Specific implementation manners

[0035] The following further elaborates in detail on a method for realizing multiplex information anti-counterfeiting by solvent-stimulated perovskite / polymer thin film color change of the present invention in conjunction with the accompanying drawings.

[0036] Combined with the attached Figures 1-9 , the present invention will be introduced in detail.

[0037] A method for realizing multiplex information anti-counterfeiting by solvent-stimulated perovskite / polymer thin film color change. The present invention first prepares a multiplex fluorescence thin film, and then realizes information anti-counterfeiting encryption through the obtained fluorescence thin film.

[0038] The preparation method of the fluorescence thin film is as follows:

[0039] Step 1: Place polyvinylidene fluoride (PVDF), CsX (X = Br, I), PbX2 (X = Cl, Br, I), and N,N-dimethylformamide (DMF) in a sample bottle in a certain proportion, heat and stir on a stirrer until dissolved to obtain a perovskite precursor solution;

[0040] Step 2: Take a certain amount of the perovskite precursor solution obtained in Step 1 and spin-coat it on a glass slide to prepare a perovskite thin film;

[0041] Step 3: Place the perovskite thin film obtained in Step 2 in an oven for heating;

[0042] Step 4: Immerse the perovskite thin film heated in Step 3 into an acetone solvent respectively. Take out the thin film after soaking for a certain time to obtain CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescence thin films.

[0043] Based on the fluorescence thin film prepared by the above method of the present invention, the invention also provides a method for realizing information encryption of the above fluorescence thin film. The specific steps are as follows:

[0044] Step 5: After arranging the patterns of CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescence thin films with different PVDF contents in Step 4, soak them in acetone for different times to obtain different color-changing patterns;

[0045] Step 6: Numerically encode the different color-changing patterns of the CsPbBrCl2, CsPbBr3, or CsPbI3 fluorescent films to obtain different digital combinations. Then, alphabetically encode the different digital combinations. Immerse the CsPbBrCl2, CsPbBr3, or CsPbI3 fluorescent films with different PVDF contents in acetone for a certain period of time, and decrypt the English words according to the obtained digital combinations and alphabetical encoding.

[0046] Step 7: Encode the different color changes of the CsPbBrCl2, CsPbBr3, or CsPbI3 fluorescent films, alphabetically encode the different digital combinations, and define their tones. Immerse the CsPbBrCl2, CsPbBr3, or CsPbI3 fluorescent films with different PVDF contents in acetone for a certain period of time, decrypt the Chinese characters according to the digital combinations, alphabetical encoding, and determination of tones, and combine them into complete sentences.

[0047] In some embodiments of the present invention, in Step 1, the mass ratio of the raw materials is polyvinylidene fluoride: the total amount of (CsX, PbX2, N,N-dimethylformamide) in the precursor solution = 10%, 15%, 20%, where the molar ratio of cesium iodide to lead iodide is 1:1, and 1 mmol CsX corresponds to 5 ml DMF.

[0048] In some embodiments of the present invention, in Step 2, 1 ml of the perovskite precursor solution is taken, and the spinning time of the precursor is 30 s and the rotation speed is 4000 rpm.

[0049] In some embodiments of the present invention, in Step 3, the heating temperature is 80 °C and the time is 10 min.

[0050] In some embodiments of the present invention, in Step 4, the acetone soaking times are 0 min, 2 min, 4 min, 6 min, 8 min, and 10 min respectively.

[0051] In some embodiments of the present invention, in Step 5, the contents of PVDF are 10%, 15%, and 20% respectively, and the soaking times are 0 min, 6 min, 10 min, 15 min, and 20 min respectively.

[0052] In some embodiments of the present invention, in Step 6, the contents of PVDF are 10%, 15%, and 20% respectively, and the soaking time is 10 min.

[0053] In some embodiments of the present invention, in Step 7, the contents of PVDF are 10%, 15%, and 20% respectively, and the soaking time is 10 min.

[0054] The specific implementation process of the present invention for using acetone to stimulate the color change of perovskite / polymer films for information encryption is as follows:

[0055] Example 1:

[0056] This example provides a method for realizing information encryption by changing the color of a CsPbI3 polymer thin film soaked in acetone, which specifically includes the following steps:

[0057] Step 1: Mix polyvinylidene fluoride and the precursor solution (cesium iodide, lead iodide, N,N-dimethylformamide) at mass ratios of 10%, 15%, and 20% respectively. The molar ratio of cesium iodide to lead iodide is 1:1, and 1 mmol CsI corresponds to 5 ml DMF. Mix them in a sample bottle and heat and stir on a stirrer until dissolved to obtain a CsPbI3 precursor solution;

[0058] Step 2: Take 1 ml of the precursor solution from Step 1 and spin-coat it on a glass slide for 30 s at a rotation speed of 4000 rpm;

[0059] Step 3: Place the thin film obtained by spin-coating the precursor solution in Step 2 in an oven and heat it at 80 °C for 10 min to obtain a CsPbI3 thin film;

[0060] Step 4: Immerse the thin film obtained after heating in Step 3 in acetone for 0 min, 2 min, 4 min, 6 min, 8 min, and 10 min respectively. The fluorescence spectra of the CsPbI3 thin films obtained after immersion are as Figure 1 shown.

[0061] Step 5: After arranging the patterns of the CsPbI3 fluorescent thin films with 10%, 15%, and 20% PVDF content in Step 4, immerse them in acetone for 0 min, 6 min, 10 min, 15 min, and 20 min to obtain different color-changing patterns, presenting the numbers "1" and "2", which can be encoded and used for information transmission. Transmission electron microscope (TEM) images of the CsPbI3 thin films treated with acetone for 0 min, 6 min, and 10 min are as Figure 2 shown. Spectral changes of the CsPbI3 thin films treated with acetone for 0 min and 10 min when placed in air for different times are as Figure 3 shown. The change trend of the PL spectral intensity of the CsPbI3 thin films treated with acetone for 0 min and 10 min when soaked in water for different times and the physical images of the luminescence under ultraviolet light are as Figure 4 shown. The display diagram of information decryption of the obtained thin films under acetone stimulation is as Figure 5 shown.

[0062] Step 6: Encode the different color-changing patterns of the CsPbI3 fluorescent film in Step 4, encode the obtained different digital combinations into letters, soak the CsPbI3 fluorescent films with 10%, 15%, and 20% PVDF content in acetone for 10 min, decrypt the English words according to the digital combinations and letter encodings, and the information decryption display diagrams of the digital combinations and letter definitions of the obtained films under acetone stimulation are as Figure 6 shown.

[0063] Step 7: Encode the different color-changing patterns of the CsPbI3 fluorescent film in Step 4, encode the different digital combinations into letters, and define their tones. Soak the CsPbI3 fluorescent films with 10%, 15%, and 20% PVDF content in acetone for 10 min, decrypt the Chinese characters according to the digital combinations, letter encodings, and tone definitions, and the information decryption schematic diagrams of the three-dimensional color encoding of the obtained films based on digital encoding, letter combinations, and tone definitions are as Figure 9 shown.

[0064] Example 2:

[0065] This example provides a method for realizing information encryption by changing the color of a CsPbBr3 polymer film soaked in acetone, which specifically includes the following steps:

[0066] Step 1: Mix polyvinylidene fluoride and the precursor solution (cesium bromide, lead bromide, N,N-dimethylformamide) at mass ratios of 10%, 15%, and 20% respectively. The molar ratio of cesium bromide to lead bromide is 1:1, and 1 mmol CsBr corresponds to 5 ml DMF. Mix and place them in a sample bottle, heat and stir on a stirrer until dissolved to obtain a CsPbBr3 precursor solution;

[0067] Step 2: Take 1 ml of the precursor solution in Step 1 and spin-coat it on a glass slide. The spin-coating time is 30 s and the rotation speed is 4000 rpm;

[0068] Step 3: Place the film obtained by spin-coating the precursor solution in Step 2 in an oven and heat it at 80 °C for 10 min to obtain a CsPbBr3 film;

[0069] Step 4: Soak the films obtained after heating in Step 3 in acetone for 0 min, 2 min, 4 min, 6 min, 8 min, and 10 min respectively. The fluorescence spectra of the CsPbBr3 films obtained after soaking are as Figure 7 shown.

[0070] Step 5: Encode the different color-changing patterns of the CsPbBr3 fluorescent film in Step 4, encode different digital combinations into letters, and define their tones. Immerse the CsPbBr3 fluorescent films with 10%, 15%, and 20% PVDF content in acetone for 10 minutes, and decrypt Chinese characters according to the digital combinations, letter encodings, and tone definitions. The information decryption schematic of the three-dimensional color encoding of the obtained film based on digital encoding, letter combination, and tone definition is as Figure 9 shown.

[0071] Example 3:

[0072] This example provides a method for realizing information encryption by changing the color of a CsPbBrCl2 polymer film soaked in acetone, which specifically includes the following steps:

[0073] Step 1: Mix polyvinylidene fluoride and the precursor solution (cesium bromide, lead chloride, N,N-dimethylformamide, acetone) at mass ratios of 10%, 15%, and 20% respectively. The molar ratio of cesium bromide to lead chloride is 1:1, and 1 mmol CsBr corresponds to 5 ml DMF. Mix them in a sample bottle and heat and stir on a stirrer until dissolved to obtain a CsPbBrCl2 precursor solution;

[0074] Step 2: Take 1 ml of the precursor solution in Step 1 and spin-coat it on a glass slide. The spin-coating time is 30 s and the rotation speed is 4000 rpm;

[0075] Step 3: Place the film obtained by spin-coating the precursor solution in Step 2 in an oven and heat it at 80 °C for 10 minutes to obtain a CsPbBrCl2 film;

[0076] Step 4: Immerse the films obtained after heating in Step 3 in acetone for 0 min, 2 min, 4 min, 6 min, 8 min, and 10 min respectively. The fluorescence spectra of the CsPbBrCl2 films obtained after immersion are as Figure 8 shown.

[0077] Step 5: Encode the different color-changing patterns of the CsPbBrCl2 fluorescent film in Step 4, encode the obtained different digital combinations into letters, and define their tones. Immerse the CsPbBrCl2 fluorescent films with 10%, 15%, and 20% PVDF content in acetone for 10 minutes, and decrypt Chinese characters according to the digital combinations, letter encodings, and tone definitions. The information decryption schematic of the three-dimensional color encoding of the obtained film based on digital encoding, letter combination, and tone definition is as Figure 9 shown.

[0078] The method of the present invention prepares a series of perovskite / polymer films by a simple method, which undergoes significant multiple fluorescence color changes under a single stimulus of acetone solvent, and can achieve higher-order information encryption through the evolution of multiple states. The film before and after the color change has good stability, and there is no obvious luminescence attenuation after being placed in the air for 100 days; and the luminescence intensity is maintained at a good level after being immersed in an aqueous solution for 120 days. The design of the present invention is reasonable and worthy of promotion.

[0079] The present invention and its implementation methods are described above, and such description is not restrictive. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design structures and embodiments similar to the technical solution without creativity, which should all fall within the protection scope of the present invention.

Claims

1. A method for anti-counterfeiting of multiplet information by solvent-stimulated color change of perovskite / polymer thin films, characterized in that: Multiplex information encryption is achieved by stimulating the fluorescence color change of perovskite / polymer films with acetone, including the following steps: Step 1: Place polyvinylidene fluoride PVDF, CsX, PbX2, and N,N-dimethylformamide DMF in a sample bottle in a certain proportion, heat and stir on a stirrer until dissolved to obtain a perovskite precursor solution; in CsX, X = Br, I; in PbX2, X = Cl, Br, I; Step 2: Take a certain amount of the perovskite precursor solution obtained in Step 1 and spin-coat it on a glass slide to prepare a perovskite film; Step 3: Place the perovskite film obtained in Step 2 in an oven for heating; Step 4: Immerse the perovskite film heated in Step 3 in an acetone solvent respectively, and soak for a certain time to obtain CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescent films; Step 5: After arranging the patterns of CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescent films with different PVDF contents in Step 4, soak them in acetone for different times to obtain different color-changing patterns; Step 6: Perform digital coding on the different color-changing patterns of CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescent films to obtain different digital combinations, perform letter coding on the different digital combinations, soak the CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescent films with different PVDF contents in acetone for a certain time, and decrypt English words according to the obtained digital combinations and letter coding; Step 7: Code the different color-changing patterns of the CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescent films, perform letter coding on the different digital combinations, and define their tones. Soak the CsPbBrCl2, CsPbBr3 or CsPbI3 fluorescent films with different PVDF contents in acetone for a certain time, decrypt Chinese characters according to the determination of digital combinations, letter coding and tones, and combine them into complete sentences.

2. The method according to claim 1, wherein In Step 1, the mass ratio of raw materials is polyvinylidene fluoride PVDF: total amount of CsX, PbX2, N,N-dimethylformamide DMF in the precursor solution = 10%, 15%, 20%, where the molar ratio of CsX and PbX2 is 1:1, and 1 mmol CsX corresponds to 5 ml DMF.

3. The method according to claim 1, characterized in that In Step 1, the perovskite is CsPbX3 nanocrystals, where CsPbX3 are CsPbBrCl2, CsPbBr3 or CsPbI3 respectively.

4. The method according to claim 1, characterized in that In Step 2, 1 ml of the perovskite precursor solution is taken, and the spinning time of the precursor is 30 s and the rotation speed is 4000 rpm.

5. The method according to claim 1, wherein In Step 3, the heating temperature is 80 °C and the time is 10 min.

6. The method according to claim 1, wherein In Step 4, the acetone soaking times are 0 min, 2 min, 4 min, 6 min, 8 min, 10 min respectively.

7. The method according to claim 1, wherein In Step 5, the contents of PVDF are 10%, 15%, 20% respectively, and the soaking times are 0 min, 6 min, 10 min, 15 min, 20 min respectively.

8. The method according to claim 1, wherein In step 6, the contents of PVDF are 10%, 15%, and 20% respectively, and the soaking time is 10 min.

9. The method according to claim 1, wherein In step 7, the contents of PVDF are 10%, 15%, and 20% respectively, and the soaking time is 10 min.

10. Application of the solvent-stimulated perovskite / polymer film in any one of the methods of claims 1-9 in the field of information encryption.

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