Copper-based nanocrystalline material for multiple fluorescent falsification prevention

Abstract

The invention discloses a copper-based nanocrystalline material for multiple fluorescent falsification prevention, the chemical formula of the copper-based nanocrystalline material is Cs5Cu3Cl6I2, the copper-based nanocrystalline material is used as an anti-counterfeiting material to be coated on an encryption material to form an anti-counterfeiting mark, the copper-based nanocrystalline material has multiple anti-counterfeiting effects, the first anti-counterfeiting is to generate characteristic fluorescence under the excitation of ultraviolet light, and the second anti-counterfeiting is to generate characteristic fluorescence under the excitation of ultraviolet light; according to the second anti-counterfeiting step and the third anti-counterfeiting step, the anti-counterfeiting mark is added into a proper solvent, light can be converted into dark blue from sky blue, then a polar solvent is added again, the light can be converted into yellow, the polar solvent can be converted into dark blue again after being completely volatilized, and the light can return to sky blue again after the solvent is added again; in the fourth anti-counterfeiting step, the temperature of the anti-counterfeiting mark is raised to change from sky blue to green; and reducing the temperature to recover sky blue. The invention has the advantages of no toxicity, high luminous efficiency, long service life, good stability and the like, encryption and decryption have recoverability, encrypted information damage caused by operations of multiple times of encryption, decryption and the like is avoided, and the anti-counterfeiting effect is obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of fluorescent anti-counterfeiting materials, and in particular to a copper-based nanocrystalline material for multiple fluorescent anti-counterfeiting. Background Art

[0002] In recent years, there are more and more knockoffs and counterfeits on the market, so people have a growing demand for advanced anti-counterfeiting materials. Emerging lead halide perovskite nanocrystals are widely used in the anti-counterfeiting field due to their advantages such as high photoluminescence quantum yield, adjustable emission wavelength, and simple synthesis method. However, the inherent toxic element lead and its instability in lead halide perovskites cast a shadow on their practical application, and most of the current fluorescent materials are single anti-counterfeiting, which is obviously not enough for the current market.

[0003] Copper-based nanocrystals, with their excellent stability and high fluorescence quantum yield, meet the market's demand for anti-counterfeiting that is easy to prepare, non-toxic, and highly stable, and are an ideal new anti-counterfeiting material.

[0004] Chinese patent CN 113306326 A provides a preparation and anti-counterfeiting application of a copper-based material, but the patent only provides one-layer anti-counterfeiting, which is difficult to meet the current anti-counterfeiting needs. Therefore, it is urgent to seek a multi-fluorescent anti-counterfeiting material. Summary of the invention

[0005] The purpose of the present invention is to provide a copper-based nanocrystalline material for multiple fluorescent anti-counterfeiting.

[0006] The present invention provides a use of a copper-based nanocrystal as a multi-fluorescent anti-counterfeiting material. The copper-based nanocrystal has a chemical formula of Cs 5 Cu 3 Cl 6 I 2 .

[0007] Preferably, the use is to coat the copper-based nanocrystals as anti-counterfeiting materials on the encryption materials to form anti-counterfeiting marks.

[0008] Specifically, copper-based nanocrystals are used to make anti-counterfeiting ink, which is coated on the encryption material to form an anti-counterfeiting mark.

[0009] Preferably, the process of encrypting and decrypting the anti-counterfeiting mark is as follows:

[0010] When the anti-counterfeiting mark is placed under natural light, there is no change, thus achieving information encryption;

[0011] The anti-counterfeiting mark is irradiated with ultraviolet light, and the anti-counterfeiting mark emits bright sky blue fluorescence, which is the first level of anti-counterfeiting.

[0012] Specifically, the wavelength of the ultraviolet light is 254nm-310nm.

[0013] Preferably, the process of encrypting and decrypting the anti-counterfeiting mark is as follows:

[0014] When the anti-counterfeiting mark is placed under natural light, there is no change, thus achieving information encryption;

[0015] After the anti-counterfeiting mark is sprayed with an organic solution containing iodine-containing ligands, it is irradiated with ultraviolet light, and the anti-counterfeiting mark emits a bright dark blue fluorescence; after spraying a polar solvent, it is irradiated with ultraviolet light, and the anti-counterfeiting mark emits a bright yellow fluorescence; after the polar solvent evaporates, it is irradiated with ultraviolet light again, and it emits a bright dark blue fluorescence again. This is the second level of anti-counterfeiting.

[0016] Specifically, the iodine-containing ligand is one or more of oleylamine iodide, cyclohexylamine iodide, oleic acid iodine, and octyl ammonium iodide.

[0017] Specifically, the organic solvent is one of n-hexane, n-butane, n-octane, n-pentane and toluene.

[0018] Specifically, the polar solvent is one of water, ethanol and methanol.

[0019] Specifically, the wavelength of the ultraviolet light is 254nm-310nm.

[0020] Preferably, the process of encrypting and decrypting the anti-counterfeiting mark is as follows:

[0021] When the anti-counterfeiting mark is placed under natural light, there is no change, thus achieving information encryption;

[0022] After the anti-counterfeiting mark is sprayed with an organic solution containing iodine-containing ligands and irradiated with ultraviolet lamp, the anti-counterfeiting mark emits bright dark blue fluorescence; after spraying with an organic solution containing chlorine-containing ligands and irradiating with ultraviolet lamp, the anti-counterfeiting mark emits bright sky blue fluorescence, which is the third level of anti-counterfeiting.

[0023] Specifically, the iodine-containing ligand is one or more of oleylamine iodide, cyclohexylamine iodide, oleic acid iodine, and octyl ammonium iodide.

[0024] Specifically, the chlorine-containing ligand is one or more of oleyl chloride, octylamine chloride and oleylamine chloride.

[0025] Specifically, the organic solvent is one of n-hexane, n-butane, n-octane, n-pentane and toluene.

[0026] Specifically, the wavelength of the ultraviolet light is 254nm-310nm.

[0027] Preferably, the process of encrypting and decrypting the anti-counterfeiting mark is as follows:

[0028] When the anti-counterfeiting mark is placed under natural light, there is no change, thus achieving information encryption;

[0029] When the anti-counterfeiting mark is heated to above 140°C, the fluorescence of the anti-counterfeiting mark turns green, and when the temperature is cooled to room temperature, the fluorescence returns to sky blue. This is the fourth level of anti-counterfeiting.

[0030] Specifically, the wavelength of the ultraviolet light is 254nm-310nm.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1) Compared with the existing copper-based fluorescent anti-counterfeiting materials, the present invention has multiple anti-counterfeiting functions and is safer. Moreover, its anti-counterfeiting effect relies on the unique physical and chemical properties of the material and is difficult to imitate;

[0033] 2) This material has good stability and can have fluorescent properties for a long time, realizing the anti-counterfeiting function. This material has high brightness and is easy to distinguish;

[0034] 3) The product of the present invention is recoverable, reducing the risk of information loss caused by encryption and decryption cycles;

[0035] 4) This material is non-toxic and remains stable in the environment, and is environmentally friendly and has good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Cs 5 Cu 3 Cl 6 I 2 PL and PLE spectra;

[0037] Figure 2 It is a photo of the anti-counterfeiting mark under 300nm ultraviolet light;

[0038] Figure 3 is the PL spectrum corresponding to the color change of the anti-counterfeiting mark in Examples 1-4;

[0039] Figure 4 It is a diagram of the color change (physical) cycle process of the anti-counterfeiting mark of Examples 1-4;

[0040] Figure 5 PL changes of the anti-counterfeiting mark in Example 4 at room temperature and 140°C. DETAILED DESCRIPTION

[0041] The present invention will be described in detail below through specific embodiments and drawings.

[0042] It should be noted that the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of description and are not used to limit the scope of implementation. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of this application without substantially changing the technical content.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0044] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0045] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement or value. The degree of flexibility for a particular variable can be easily determined by one skilled in the art.

[0046] As used herein, the term "at least one of" is intended to be synonymous with "one or more of." For example, "at least one of A, B, and C" expressly includes only A, only B, only C, and combinations of each thereof.

[0047] The present invention successfully prepared Cs 5 Cu 3 Cl 6 I 2 Nanocrystals, their PL and PLE spectra are as follows Figure 1 As shown. Prepare to 5 Cu 3 Cl 6 I 2 When the nanocrystals are post-processed to improve their optical properties, it is found that they have a special luminescence and color change phenomenon, so the present invention applies it in the field of anti-counterfeiting technology.

[0048] Example 1

[0049] 1) Prepare Cs 5 Cu 3 Cl 6 I 2 The n-hexane solution is printed on the label paper, and after drying, it is placed under natural light. If there is no change, an invisible anti-counterfeiting mark can be obtained;

[0050] 2) The anti-counterfeiting mark in step 1 is irradiated with a 300nm ultraviolet lamp, and the anti-counterfeiting mark emits a bright sky blue fluorescence, such as Figure 2 shown.

[0051] Example 2

[0052] 1) Prepare an anti-counterfeiting mark in the same manner as in Example 1;

[0053] 2) Spray the anti-counterfeiting mark in step 1 with a n-hexane solution containing oleylamine iodine, and irradiate it with a 300nm ultraviolet lamp, and the anti-counterfeiting mark emits a bright dark blue fluorescence; spray alcohol again, and irradiate it with a 300nm ultraviolet lamp, and the anti-counterfeiting mark emits a bright yellow fluorescence; after all the alcohol evaporates, irradiate it with a 300nm ultraviolet lamp, and the anti-counterfeiting mark will emit a bright dark blue fluorescence again. The anti-counterfeiting color change cycle process is as follows: Figure 4 shown.

[0054] Example 3

[0055] 1) Prepare an anti-counterfeiting mark in the same manner as in Example 1;

[0056] 2) Spray the anti-counterfeiting mark in step 1 with a n-hexane solution containing oleylamine iodine and irradiate it with a 300nm ultraviolet lamp, and the anti-counterfeiting mark emits a bright dark blue fluorescence; spray the n-hexane solution containing oleylamine chloride and irradiate it with a 300nm ultraviolet lamp, and the anti-counterfeiting mark emits a bright sky blue fluorescence. The anti-counterfeiting color change cycle process is as follows: Figure 4 As shown, PL changes as Figure 5 shown.

[0057] Example 4

[0058] 1) Prepare an anti-counterfeiting mark in the same manner as in Example 1;

[0059] 2) Heat the anti-counterfeiting mark in step 1 to above 140°C and irradiate it with a 300nm ultraviolet lamp. The fluorescence of the anti-counterfeiting mark turns green. When the temperature cools to room temperature, irradiate it with a 300nm ultraviolet lamp and the fluorescence returns to sky blue. Figure 4 , 5 shown.

[0060] In summary, Figure 3 is the PL spectrum corresponding to the color change of the anti-counterfeiting mark in Examples 1-4, from Figure 3 It can be seen that the PL peak corresponding to dark blue is 441nm; the PL peak corresponding to sky blue is 468nm; the PL peak corresponding to green is 511nm; and the PL peak corresponding to dark blue is 559nm.

[0061] The above-mentioned implementation cases are only preferred implementation cases in the present invention, but the implementation methods of the present invention are not limited to the above-mentioned implementation cases. For example, various forms of combinations of the schemes in the embodiments, any other changes, modifications, substitutions, and combinations made without departing from the spirit and principles of the present invention should be equivalent replacement methods and are within the protection scope of the present invention.

Claims

1. A use of copper-based nanocrystals as a multi-fluorescent anti-counterfeiting material, characterized in that: The copper-based nanocrystal has the chemical formula Cs5Cu3Cl6I2.

2. The use according to claim 1, characterized in that The use mentioned is to coat copper-based nanocrystals as anti-counterfeiting materials on encryption materials to form anti-counterfeiting marks.

3. The use according to claim 1 or 2, characterized in that The process of encrypting and decrypting the anti-counterfeiting mark is as follows: When the anti-counterfeiting mark is placed under natural light, there is no change, thus achieving information encryption; The anti-counterfeiting mark is irradiated with ultraviolet light, and the anti-counterfeiting mark emits bright sky blue fluorescence.

4. The use according to claim 1 or 2, characterized in that The process of encrypting and decrypting the anti-counterfeiting mark is as follows: When the anti-counterfeiting mark is placed under natural light, there is no change, thus achieving information encryption; After the anti-counterfeiting mark is sprayed with an organic solution containing an iodine-containing ligand, it is irradiated with an ultraviolet lamp, and the anti-counterfeiting mark emits a bright dark blue fluorescence; after spraying a polar solvent, it is irradiated with an ultraviolet lamp, and the anti-counterfeiting mark emits a bright yellow fluorescence; after the polar solvent evaporates, it is irradiated with an ultraviolet lamp again, and it emits a bright dark blue fluorescence again.

5. The use according to claim 1 or 2, characterized in that The process of encrypting and decrypting the anti-counterfeiting mark is as follows: When the anti-counterfeiting mark is placed under natural light, there is no change, thus achieving information encryption; After the anti-counterfeiting mark is sprayed with an organic solution containing iodine-containing ligands and irradiated with an ultraviolet lamp, the anti-counterfeiting mark emits bright dark blue fluorescence; after spraying with an organic solution containing chlorine-containing ligands and irradiating with an ultraviolet lamp, the anti-counterfeiting mark emits bright sky blue fluorescence.

6. The use according to claim 1 or 2, characterized in that The process of encrypting and decrypting the anti-counterfeiting mark is as follows: When the anti-counterfeiting mark is placed under natural light, there is no change, thus achieving information encryption; When the anti-counterfeiting mark is heated to above 140°C, the fluorescence of the anti-counterfeiting mark turns green, and when the temperature is cooled to room temperature, the fluorescence returns to sky blue.

7. The use according to any one of claims 3 to 6, characterized in that: The wavelength of ultraviolet light is 254 nm-310 nm.

8. The use according to claim 4 or 5, characterized in that The iodine-containing ligand is one or more of oleylamine iodine, cyclohexylamine iodine, oleic acid iodine and octylammonium iodide; the organic solvent is one of n-hexane, n-butane, n-octane, n-pentane and toluene.

9. The use according to claim 4, characterized in that The polar solvent is one of water, ethanol and methanol.

10. The use according to claim 5, characterized in that The chlorine-containing ligand is one or more of oleyl chloride, octylamine chloride and oleylamine chloride.

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