Preparation method of lead-free double perovskite material and application of lead-free double perovskite material in anti-counterfeiting field

Abstract

The invention belongs to the technical application field of perovskite materials, and discloses a preparation method and application of a lead-free double perovskite material. The invention provides an extremely simple synthesis method, and the precursor solution is used for replacing printer ink and can be well applied to an ink-jet printing technology. The fluorescent characteristic of the lead-free double perovskite material is utilized, the lead-free double perovskite material is used as an effective detection means, the application of the novel lead-free double perovskite material in the ink-jet printing anti-counterfeiting field is researched and developed, the technology can realize high-precision anti-counterfeiting marks which are difficult to copy by printing unique structures or patterns, the safety and the recognition degree of products are enhanced, and the anti-counterfeiting effect is good. The method can be better applied to the anti-counterfeiting field.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescent anti-counterfeiting, and specifically relates to a lead-free double perovskite material used in the anti-counterfeiting field, a preparation method and the application of the material in the anti-counterfeiting field. Background Art

[0002] At present, traditional anti-counterfeiting technologies mainly include special inks, watermark anti-counterfeiting, magnetic ink fluorescent fibers and other means. These technologies mainly use physical or chemical methods to add special marks on products or product packaging to achieve anti-counterfeiting functions. However, these technologies have disadvantages such as high cost and easy cracking. These traditional anti-counterfeiting methods can no longer meet the needs of modern society. Therefore, developing more efficient, accurate and difficult to copy anti-counterfeiting technologies has become a common goal pursued by scientific researchers.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and to provide a lead-free double perovskite material for use in the field of anti-counterfeiting. The present invention utilizes the fluorescent properties of the lead-free double perovskite material as an effective detection method to study and develop the application of a new type of lead-free double perovskite material in the field of inkjet printing anti-counterfeiting. The technology can achieve high-precision, difficult-to-copy anti-counterfeiting marks by printing unique structures or patterns, enhance the safety and recognition of products, and can be better applied in the field of anti-counterfeiting.

[0005] The second object of the present invention is to provide a method for preparing the above-mentioned lead-free double perovskite material, which has simple synthesis and solves the problem of complex synthesis process.

[0006] The third object of the present invention is to provide a fluorescent anti-counterfeiting technology, which uses double perovskite materials in inkjet printers.

[0007] In order to solve the above technical problems, the present invention is implemented through the following technical solutions: A double perovskite luminescent anti-counterfeiting material, the chemical formula of the double perovskite luminescent anti-counterfeiting material is Cs2NaY x Yb y Er z , wherein x+y+z=1, 0.25≤x≤0.8, 0.20≤y≤0.70, 0.02≤z≤0.05. The double perovskite luminescent anti-counterfeiting material is prepared by co-doping a single-component double perovskite fluorescent material with yttrium, ytterbium and erbium, that is, in a double perovskite material with a specific crystal structure, its properties are adjusted by co-doping (i.e., introducing two or more different doping elements, i.e., Y, Yb and Er), thereby obtaining a material with excellent fluorescent properties.

[0008] A method for preparing the above-mentioned double perovskite luminescent anti-counterfeiting material comprises the following steps: a) preparing a precursor solution: uniformly dispersing cesium chloride, sodium chloride, yttrium chloride, ytterbium chloride and erbium chloride in water according to a certain proportion to form a precursor solution; b) The precursor solution is placed in an oven and dried to form double perovskite crystals, which are double perovskite luminescent anti-counterfeiting materials.

[0009] Specifically, in step b), drying is performed at 60-100° C. for 24-60 h.

[0010] The present invention provides application of the double perovskite luminescent anti-counterfeiting material in the field of anti-counterfeiting.

[0011] The present invention provides a method for using the above double perovskite luminescent anti-counterfeiting material in a printer, which comprises the following steps: 1) Dissolving 1 mmol of the double perovskite luminescent anti-counterfeiting material in 0.5-3 mL of water to obtain an anti-counterfeiting material solution A; adding the obtained anti-counterfeiting material solution A to a printer cartridge instead of ink, printing an anti-counterfeiting pattern or text on A4 paper, and then drying it in an oven; 2) When the dried A4 paper is irradiated with a 980 nm laser, a bright green light is found at the location where the anti-counterfeiting pattern or text is printed.

[0012] Specifically, the printer used in step 1) is an inkjet printer, and the printer can select a rough paper high-quality printing mode when printing. The printer can print repeatedly 1 to 30 times. The paper used is ordinary A4 paper for printing.

[0013] Furthermore, in step 1), the oven temperature is set to 50-80°C, and the drying time is 1-5 min.

[0014] Specifically, in step 2), the laser power is adjusted to 0.5-5 W.

[0015] The present invention also provides an anti-counterfeiting printing method for an inkjet printer, which comprises the following steps: 2 mmol cesium chloride, 1 mmol sodium chloride, 0.25-0.8 mmol yttrium chloride, 0.20-0.70 mmol ytterbium chloride and 0.02-0.05 mmol erbium chloride are uniformly dispersed (the dispersion can be uniformly achieved by ultrasonic treatment at room temperature for 20-30 min) in 1-10 mL water to form a precursor solution B; the obtained precursor solution B is added to the printer cartridge instead of ink, and an anti-counterfeiting pattern or text is printed on A4 paper, which is then dried in an oven at 50-80°C for 1-5 min; a 980 nm laser is used to irradiate the dried A4 paper, and it is found that a bright green light is emitted at the location where the anti-counterfeiting pattern or text is printed.

[0016] Fluorescent anti-counterfeiting technology has become an important technology in the field of anti-counterfeiting due to its unique optical properties. This technology can make the anti-counterfeiting mark emit fluorescence under the irradiation of a specific light source, thereby quickly identifying the authenticity of the product. Lead-free double perovskite materials are an emerging luminescent material with a wide luminescence range, efficient optical properties and low toxicity. Their general formula is usually expressed as A2M(I)M(III)X6, where A represents a monovalent cation, such as cesium (Cs + ), M(I) and M(III) are respectively a combination of monovalent and trivalent metal ions, and X is a halogen ion. This unique structure gives them excellent chemical stability and environmental friendliness, making them perform well in security applications such as anti-counterfeiting, authentication, and information encryption. Therefore, using the fluorescence properties of lead-free double perovskite materials as an effective detection method, researching and developing new lead-free double perovskite materials for the field of inkjet printing anti-counterfeiting is of great significance for improving anti-counterfeiting performance and reducing costs.

[0017] The present invention proposes an extremely simple synthesis method, and replaces printer ink with a precursor solution, which can be well applied to inkjet printing technology. By utilizing the fluorescence characteristics of lead-free double perovskite materials and using them as an effective detection method, the application of new lead-free double perovskite materials in the field of inkjet printing anti-counterfeiting has been studied and developed. This technology can achieve high-precision, difficult-to-copy anti-counterfeiting marks by printing unique structures or patterns, enhance the safety and recognition of products, and can be better applied in the field of anti-counterfeiting. Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention adopts an extremely simple preparation method, prepares and synthesizes double perovskite luminescent materials under mild conditions, utilizes the excellent luminescent properties of the double perovskite luminescent materials, uses the precursor solution of the material or the solution of the material redissolved in water instead of ink for inkjet printers, and designs text or patterns to be printed on A4 paper, and emits bright green light for anti-counterfeiting by irradiation with a 980 nm laser. The preparation method of the present invention is simple, easy to operate, mild conditions, strong practicality, and the anti-counterfeiting performance is simple and easy to achieve. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The double perovskite luminescent material (Cs2NaY 0.78 Yb 0.2 Er 0.02 ) The morphology of the anti-counterfeiting pattern printed on A4 paper using the precursor solution instead of ink and dried under a scanning electron microscope; Figure 2 The double perovskite crystal (Cs2NaY 0.78 Yb 0.2 Er 0.02) and its precursor solution instead of ink to print anti-counterfeiting patterns on A4 paper after drying; Figure 3 The double perovskite luminescent material (Cs2NaY 0.78 Yb 0.2 Er 0.02 ) Fluorescence emission spectrum of the anti-counterfeiting pattern printed on A4 paper using the precursor solution instead of ink after drying; Figure 4 The double perovskite luminescent material (Cs2NaY 0.78 Yb 0.2 Er 0.02 )The precursor solution replaces ink to print the anti-counterfeiting pattern on A4 paper, and the digital electronic photo under near-infrared excitation after drying; Figure 5 The double perovskite luminescent crystal (Cs2NaY 0.78 Yb 0.2 Er 0.02 ) was redissolved in water to obtain a crystal solution to replace ink for printing anti-counterfeiting patterns on A4 paper, and then dried and subjected to digital electronic photographs under near-infrared excitation. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

[0020] In the following examples, unless otherwise specified, all raw materials used are common commercially available products that can be directly purchased.

[0021] Room temperature refers to 25±5°C.

[0022] Embodiment 1: A very simple double perovskite material (Cs2NaY 0.78 Yb 0.2 Er 0.02 ), comprising: First, 336.72 mg (2 mmol) of CsCl, 58.44 mg (1 mmol) of NaCl, 236.62 mg (0.78 mmol) of YCl3·6H2O, 77.5 mg (0.2 mmol) of YbCl3·6H2O, and 5.47 mg (0.02 mmol) of ErCl3·6H2O were placed in a container, and 1 mL of ultrapure water was added, and ultrasonicated at room temperature for 25 min to form a precursor solution. The precursor solution was then dried at 80 °C for 48 h to form double perovskite crystals (see Figure 2 ). Figure 2The XRD data can prove that double perovskite crystals are prepared.

[0023] Embodiment 2: A method for using a double perovskite material in an inkjet printer, comprising: The precursor solution obtained in Example 1 or 1 mmol of the double perovskite crystal obtained in Example 1 was redissolved in 2 mL of water to obtain a crystal solution, which was added to the grinding box of an inkjet printer instead of ink. The anti-counterfeiting pattern or text was printed on A4 paper in the rough paper high-quality printing mode, and the printing was repeated 5 times, and then dried at 60° C. for 2 min. The A4 paper was further irradiated with a 980 nm laser, and the laser power was adjusted to 3 W. It can be seen that the place where the anti-counterfeiting pattern or text was printed emits bright green light.

[0024] Figure 1 The double perovskite luminescent material (Cs2NaY 0.78 Yb 0.2 Er 0.02 ) The precursor solution is used instead of ink to print the anti-counterfeiting pattern on A4 paper. The morphology photograph under a scanning electron microscope after drying shows that the double perovskite luminescent material appears as block particles on the A4 paper with good crystallinity.

[0025] Figure 2 The double perovskite crystal prepared in Example 1 and the double perovskite luminescent material (Cs2NaY 0.78 Yb 0.2 Er 0.02 ) The XRD pattern of the crystal obtained by repeatedly printing the anti-counterfeiting pattern on A4 paper 30 times with the precursor solution instead of ink and then drying it. It can be seen from the figure that the diffraction peak of the crystal obtained by repeatedly printing the anti-counterfeiting pattern 30 times and drying it can still correspond well to the Cs2NaYCl6 phase, and it is a cubic double perovskite structure.

[0026] Figure 3 The double perovskite luminescent material (Cs2NaY 0.78 Yb 0.2 Er 0.02 ) The precursor solution is used instead of ink to print the anti-counterfeiting pattern on A4 paper and then dried. The fluorescence emission spectrum is obtained under 980 nm infrared light excitation. As can be seen from the figure: under 980 nm light excitation, the emission wavelength is between 370 nm and 710 nm, of which Er is the main 3+ Ion green emission ( 2 H 11 / 2 → 4 I 15 / 2 , 4 S 3 / 2 → 4 I15 / 2 ) and red emission ( 4 F 9 / 2 → 4 I 15 / 2 ), and overall the green emission intensity is much greater than the red emission intensity.

[0027] Figure 4 The double perovskite luminescent material (Cs2NaY 0.78 Yb 0.2 Er 0.02 ) The precursor solution is used instead of ink to print the anti-counterfeiting pattern on A4 paper. The digital electronic photo taken after drying under near-infrared excitation shows that the anti-counterfeiting pattern appears bright green under the irradiation of a 980 nm infrared laser, indicating that the material has a good anti-counterfeiting effect.

[0028] Figure 5 The double perovskite luminescent material (Cs2NaY 0.78 Yb 0.2 Er 0.02 ) was redissolved in water to obtain a crystal solution to replace ink and print the anti-counterfeiting pattern on A4 paper. The digital electronic photograph after drying under near-infrared excitation showed that the anti-counterfeiting pattern appeared bright green under the irradiation of a 980 nm infrared laser, indicating that the material still had a good anti-counterfeiting effect after redissolution and recrystallization.

[0029] In summary, the present invention uses a precursor solution of a double perovskite luminescent material or a solution of the material redissolved in water instead of ink for an inkjet printer, designs text or patterns to be printed on A4 paper, and emits bright green light for anti-counterfeiting when irradiated with a 980 nm laser.

Claims

1. A double perovskite luminescent anti-counterfeiting material, characterized in that: The chemical formula of the double perovskite luminescent anti-counterfeiting material is Cs2NaY x Yb y Er z , where x+y+z=1, 0.25≤x≤0.8, 0.20≤y≤0.70, 0.02≤z≤0.

05.

2. The method for preparing the double perovskite luminescent anti-counterfeiting material according to claim 1, characterized in that: The steps include: a) preparing a precursor solution: uniformly dispersing cesium chloride, sodium chloride, yttrium chloride, ytterbium chloride and erbium chloride in water according to a certain proportion to form a precursor solution; b) The precursor solution is placed in an oven for drying to obtain a double perovskite luminescent anti-counterfeiting material.

3. The method for preparing the double perovskite luminescent anti-counterfeiting material according to claim 1, characterized in that: In step b), drying is carried out at 60-100° C. for 24-60 h.

4. Application of the double perovskite luminescent anti-counterfeiting material according to claim 1 in the field of anti-counterfeiting.

5. A method for using the double perovskite luminescent anti-counterfeiting material according to claim 1 in a printer, characterized in that: The steps include: 1) Dissolving 1 mmol of the double perovskite luminescent anti-counterfeiting material in 0.5-3 mL of water to obtain an anti-counterfeiting material solution A; adding the obtained anti-counterfeiting material solution A to a printer cartridge instead of ink, printing an anti-counterfeiting pattern or text on A4 paper, and then drying it in an oven; 2) When the dried A4 paper is irradiated with a 980 nm laser, a bright green light is found at the location where the anti-counterfeiting pattern or text is printed.

6. The method for a printer as claimed in claim 5, characterized in that: The printer used in step 1) is an inkjet printer, which can print repeatedly 1 to 30 times.

7. The method for a printer as claimed in claim 5, characterized in that: In step 1), the oven temperature is set to 50-80°C and the drying time is 1-5 min.

8. The method for a printer as claimed in claim 5, characterized in that: In step 2), the laser power is adjusted to 0.5-5 W.

9. An anti-counterfeiting printing method for an inkjet printer, characterized in that: The steps include: 2 mmol of cesium chloride, 1 mmol of sodium chloride, 0.25-0.8 mmol of yttrium chloride, 0.20-0.70 mmol of ytterbium chloride and 0.02-0.05 mmol of erbium chloride are uniformly dispersed in 1-10 mL of water to form a precursor solution B; the obtained precursor solution B is added to the printer cartridge instead of ink, and an anti-counterfeiting pattern or text is printed on A4 paper, which is then placed in a 50-80 ℃ oven for drying for 1-5 min; a 980 nm laser is used to irradiate the dried A4 paper, and it is found that a bright green light is emitted at the location where the anti-counterfeiting pattern or text is printed.

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