Preparation and application of printable quantum dot hydrogel

Abstract

This invention relates to the field of quantum dot technology, and provides a method for preparing and applying printable quantum dot hydrogels. The quantum dot hydrogel comprises a hydrogel resin and quantum dot material dispersed in the hydrogel resin. The quantum dot material is a coated quantum dot, including perovskite quantum dots MA3Bi2Br9, and silica formed on the surface of the MA3Bi2Br9. The quantum dot hydrogel provided by this invention imparts shape plasticity to the quantum dot material, meeting the product requirements of perovskite quantum dots in fields such as anti-counterfeiting, information storage, and encryption.

Description

Technical Field

[0001] This invention belongs to the field of quantum dot technology, and particularly relates to the preparation and application of a printable quantum dot hydrogel. Background Technology

[0002] Perovskite quantum dots (Pb) possess excellent optical and electrical properties due to their unique quantum effects, making them promising candidates for applications in light-emitting diodes (LEDs) and solar cells. CsPbBr3 is one such Pb quantum dot currently under extensive research; however, the toxicity of lead (Pb) severely hinders its application development. Therefore, researchers have developed various elements, such as tin (Sn), germanium (Ge), and bismuth (Bi), to replace Pb in forming Pb-structured quantum dots. However, these lead-free Pb quantum dots generally have high defect densities, resulting in low yields and stability, significantly limiting their applications. Encapsulation with silica (SiO2) or polymers (such as PMMA and PS) can passivate the surface of Pb quantum dots, improving their fluorescence properties and stability. However, most Pb quantum dots can only be used in organic solutions, and their shape-forming ability is poor or even impossible, limiting their practical applications, such as in anti-counterfeiting, information storage, and encryption. Furthermore, the color of perovskite quantum dots poses another obstacle to their application in fields such as anti-counterfeiting, information storage, and encryption. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing and applying printable quantum dot hydrogels, the application of quantum dot hydrogels in anti-counterfeiting, information storage and encryption, and a 3D printing method, which aims to solve the problem of poor molding ability of perovskite quantum dots.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0005] The first aspect of the present invention provides a quantum dot hydrogel, comprising a hydrogel resin and a quantum dot material dispersed in the hydrogel resin, wherein the quantum dot material is a coated quantum dot, the coated quantum dot comprising perovskite quantum dot MA3Bi2Br9 and silica formed on the surface of the MA3Bi2Br9.

[0006] The quantum dot hydrogel MA3Bi2Br9 provided by this invention possesses excellent fluorescence properties and is colorless, which is beneficial for the application of perovskite quantum dots in anti-counterfeiting, information storage, and encryption. Based on this, the quantum dot material is bound within a network structure formed by the hydrogel, giving the quantum dot material shape plasticity. By adjusting the molding of the hydrogel, different quantum dot hydrogel products can be obtained, thereby enabling the application of quantum dot materials in different products with shape requirements, especially meeting the product requirements of perovskite quantum dots in anti-counterfeiting, information storage, and encryption.

[0007] In one embodiment, the hydrogel resin is selected from at least one of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, and carboxymethyl cellulose methacrylate.

[0008] In one embodiment, the mass ratio of the quantum dot material to the hydrogel resin is 0 to 1:100, and the mass of the quantum dot material is not zero. A second aspect of the present invention provides a method for preparing a quantum dot hydrogel, comprising the following steps:

[0009] A mixture of quantum dot material, hydrogel resin, photoinitiator and water is obtained and then cured under ultraviolet light to form a quantum dot hydrogel. The quantum dot material is a coated quantum dot, which includes perovskite quantum dot MA3Bi2Br9 and silicon dioxide formed on the surface of MA3Bi2Br9.

[0010] The present invention provides a method for preparing quantum dot hydrogels, using quantum dot materials, hydrogel resin, photoinitiator, and water as raw materials. Under ultraviolet conditions, the hydrogel resin undergoes cross-linking, and the resulting cross-linked structure binds the quantum dot material within it, endowing the quantum dot material with shape plasticity. This method is simple to operate and easy to control, facilitating the application of quantum dot materials in various products with shape requirements, particularly meeting the product requirements of perovskite quantum dots in fields such as anti-counterfeiting, information storage, and encryption.

[0011] In one embodiment, the hydrogel resin is selected from at least one of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, and carboxymethyl cellulose methacrylate.

[0012] In one embodiment, the photoinitiator is selected from at least one of phenyl (2,4,6-trimethylbenzoyl) lithium phosphate and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone.

[0013] In one embodiment, the hydrogel resin is selected from at least one of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, and carboxymethyl cellulose methacrylate; the photoinitiator is selected from at least one of lithium phenyl (2,4,6-trimethylbenzoyl) phosphate and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone.

[0014] In one embodiment, the mass ratio of the quantum dot material to the hydrogel resin is 0 to 1:100, and the mass of the quantum dot material is not 0.

[0015] In one embodiment, the mass ratio of the hydrogel resin to the water is 1:0 to 1, and the mass of the water is not 0.

[0016] In one embodiment, the mass ratio of the photoinitiator to the hydrogel resin is 1 to 5:1250.

[0017] In one embodiment, the mass ratio of the quantum dot material to the hydrogel resin is 0 to 1:100, and the mass of the quantum dot material is not 0; the mass ratio of the hydrogel resin to the water is 1:0 to 1, and the mass of the water is not 0; the mass ratio of the photoinitiator to the hydrogel resin is 1 to 5:1250.

[0018] In one embodiment, the ultraviolet conditions include: an excitation wavelength of 385±20nm and a laser power of 40-60W / cm². 3 .

[0019] In one embodiment, the curing process takes 1 to 10 minutes.

[0020] In one embodiment, the ultraviolet conditions include: an excitation wavelength of 385±20nm and a laser power of 40-60W / cm². 3 The curing time is 1 to 10 minutes.

[0021] A third aspect of this invention provides the application of quantum dot hydrogels in the fields of anti-counterfeiting, encryption, and information storage.

[0022] A fourth aspect of the present invention provides a 3D printing method, comprising the following steps:

[0023] A mixture is prepared by mixing quantum dot material, hydrogel resin, photoinitiator and water. The mixture includes a first mixture in which the mass percentage of quantum dot material is not 0. The quantum dot material is a coated quantum dot, which includes perovskite quantum dot MA3Bi2Br9 and silicon dioxide formed on the surface of MA3Bi2Br9.

[0024] The first mixture is printed using a 3D printer to form a first liquid film, and then a functional layer is prepared by UV curing.

[0025] The 3D printing method provided by this invention can obtain colorless quantum dot hydrogel products with three-dimensional structures, enabling the application of MA3Bi2Br9 in fields such as anti-counterfeiting, information storage, and encryption.

[0026] In one embodiment, the mixture further includes a second mixture in which the mass percentage of the quantum dot material is 0;

[0027] The method further includes: before preparing the functional layer, printing the second mixture using a 3D printer to form a second liquid film, and then curing it with ultraviolet light to prepare a first base layer; and the functional layer is formed on the surface of the first base layer.

[0028] In one embodiment, the first substrate layer consists of a single layer of hydrogel resin, or the first substrate layer comprises a plurality of stacked hydrogel resin layers.

[0029] In one embodiment, the method further includes: forming the second mixture on the surface of the functional layer using a 3D printer, and then curing it with ultraviolet light to prepare a second base layer.

[0030] In one embodiment, the second base layer consists of a single layer of hydrogel resin, or the second base layer comprises a plurality of stacked hydrogel resin layers.

[0031] In one embodiment, the functional layer comprises n quantum dot hydrogel layers stacked together along a direction perpendicular to the surface of the functional layer, and the quantum dot content in the first mixture used to prepare each quantum dot hydrogel layer is the same or different, wherein n is a natural number ≥1.

[0032] In one embodiment, a hydrogel resin layer is disposed between at least one set of adjacent quantum dot hydrogel layers. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 These are microscopic images and transparency diagrams of the quantum dot hydrogel discs and hydrogel discs provided in Embodiment 1 of the present invention.

[0035] Figure 2The fluorescence intensity diagrams of quantum dot hydrogels obtained with different amounts of MBB@SiO2 doping provided in Example 1 of this invention are shown.

[0036] Figure 3 This is a fluorescence lifetime diagram of quantum dot hydrogels obtained with different amounts of MBB@SiO2 doping provided in Example 1 of the present invention;

[0037] Figure 4 This is a mechanical lifetime diagram of quantum dot hydrogels obtained with different amounts of MBB@SiO2 doping provided in Example 1 of the present invention.

[0038] Figure 5 This is a schematic diagram of the multilayer 3D printing of the hydrogel provided in Embodiment 3 of the present invention;

[0039] Figure 6 This is a slice model diagram of the quantum dot hydrogel resin layer provided in Embodiment 3 of the present invention;

[0040] Figure 7 These are microscopic and fluorescence images of two-dimensional printed samples of the Sun Yat-sen University emblem and window-shaped horse badge provided in Embodiment 4 of the present invention.

[0041] Figure 8 This is a SEM image of the hydrogel microstructure of the beluga whale relief provided in Embodiment 5 of the present invention;

[0042] Figure 9 These are confocal Z-axis tomographic reconstruction images of the 3D printed sample at different angles provided in Example 5;

[0043] Figure 10 This is a fluorescence imaging image of the 3D printed sample provided in Embodiment 6 of the present invention;

[0044] Figure 11 This is a fluorescence image of the 3D printed sample provided in Example 7;

[0045] Figure 12 This is a fluorescence imaging image of the 3D printed part provided in Embodiment 8 of the present invention;

[0046] Figure 13 This is a fluorescence imaging image of the 3D printed sample provided in Embodiment 9 of the present invention. Detailed Implementation

[0047] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0048] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0049] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the weights mentioned in the embodiments of this invention can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0050] This invention provides a quantum dot hydrogel, comprising a hydrogel resin and a quantum dot material dispersed in the hydrogel resin. The quantum dot material is a coated quantum dot, including perovskite quantum dots MA3Bi2Br9 and silica formed on the surface of MA3Bi2Br9.

[0051] The quantum dot hydrogel provided in this embodiment of the invention includes a quantum dot material, which is a coated quantum dot, comprising a quantum dot body and silica encapsulating the quantum dots. The quantum dot body is a bismuth-containing perovskite quantum dot with the molecular formula MA3Bi2Br9. This quantum dot, coated with silica, exhibits excellent fluorescence properties and luminescence stability. More importantly, MA3Bi2Br9 is colorless and transparent, making it difficult to detect with the naked eye when used in anti-counterfeiting, encryption, and other technical fields. This effectively encrypts information and improves the security of encrypted information.

[0052] In this embodiment of the invention, silica is used to coat MA3Bi2Br9 to passivate the surface defects of MA3Bi2Br9 and improve its fluorescence properties and luminescence stability. In some embodiments, silica coating of quantum dots can be achieved by adding a silane coupling agent to the quantum dots and then heating and refluxing.

[0053] In some embodiments of the present invention, the coating of MA3Bi2Br9 with silica may take several forms. In one embodiment, the surface of one molecule of MA3Bi2Br9 is coated with silica to form a molecular dot material. In another embodiment, two or more molecules of MA3Bi2Br9 are simultaneously coated with silica to form a molecular dot material, i.e., silica simultaneously coats multiple MA3Bi2Br9 molecules. In this embodiment, preferably, the multiple MA3Bi2Br9 molecules are separated from each other by silica, i.e., the multiple MA3Bi2Br9 molecules do not agglomerate.

[0054] In this embodiment of the invention, MA3Bi2Br9 based on silica coating can also be represented as MBB@SiO2, where MBB represents MA3Bi2Br9. In some embodiments, the particle size of MBB@SiO2 is 70-150 nm.

[0055] In this embodiment of the invention, hydrogel resin refers to a type of organic material formed by the polymerization of water-soluble organic compounds. The organic compounds that form hydrogel resin are polymerized from monomers. In this embodiment of the invention, the hydrogel resin may contain only one type of monomer, or it may contain two or more types.

[0056] The monomers are polymerized and cross-linked to form a network structure. MBB@SiO2 is dispersed within this network structure and can be shaped using this structure, which is beneficial for the application of MBB@SiO2, particularly in anti-counterfeiting and information storage technologies. Specifically, due to the strong plasticity of hydrogel resin, the quantum dot hydrogel provided in this invention allows for the shaping of MBB@SiO2, thus endowing it with excellent shaping capabilities. Based on this, MBB@SiO2, as the body of encrypted information, can be given various shapes, thereby achieving three-dimensional information encryption. This allows encrypted information to be input in quaternary or even higher bases through three-dimensional printing, enabling the storage of more information within the same space, thus improving space utilization.

[0057] The hydrogel resin provided in this embodiment of the invention exhibits good stability with MBB@SiO2. This stability is manifested in the fact that the hydrogel resin and MBB@SiO2 do not react at room temperature, and the hydrogel resin does not affect the fluorescence properties and luminescence stability of MBB@SiO2. Furthermore, considering the applications of quantum dot hydrogels in anti-counterfeiting and information storage technologies, the hydrogel resin is selected from colorless and transparent hydrogel resins. In some embodiments, the hydrogel resin is selected from at least one of polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate, and carboxymethyl cellulose methacrylate. For example, the hydrogel resin is selected from polyethylene glycol diacrylate (PEGDA) with a number average molecular weight of approximately 700.

[0058] In this embodiment of the invention, the mass ratio of quantum dot material to hydrogel resin is 0 to 1:100, and the mass of quantum dot material is not zero. When the mass ratio is within this range, the quantum dot hydrogel exhibits high fluorescence intensity and good mechanical properties. For example, the mass ratio of quantum dot material to hydrogel resin can be 0.01:100, 0.05:100, 0.08:100, 0.10:100, 0.15:100, 0.18:100, 0.20:100, 0.25:100, 0.28:100, 0.30:100, 0.35:100, 0.38:100, 0.40:100, 0.45:100, 0.48:100, 0.40:100, 0.50:100, 0.60:100, 0.70:100, 0.80:100, 0.90:100, 1.0:100, etc.

[0059] The quantum dot hydrogel provided in this invention uses a network structure formed by hydrogel as the main body to bind quantum dot materials within it, giving the quantum dot materials shape plasticity. Different quantum dot hydrogel products can be obtained by adjusting the molding of the hydrogel, thereby realizing the application of quantum dot materials in different products with shape requirements. In particular, it can meet the product requirements of perovskite quantum dots in the fields of anti-counterfeiting, information storage and encryption.

[0060] The quantum dot hydrogel provided in this embodiment of the invention can be prepared by the following method.

[0061] Accordingly, embodiments of the present invention also provide a method for preparing quantum dot hydrogels, comprising the following steps:

[0062] A mixture of quantum dot material, hydrogel resin, photoinitiator and water is prepared and cured under ultraviolet light to form a quantum dot hydrogel. The quantum dot material is a coated quantum dot, which includes perovskite quantum dot MA3Bi2Br9 and silicon dioxide formed on the surface of MA3Bi2Br9.

[0063] Specifically, the method includes:

[0064] S11. A mixture is prepared by mixing quantum dot material, hydrogel resin, photoinitiator and water.

[0065] This step provides the raw materials for preparing the quantum dot hydrogel. The quantum dot material, as previously described, is a coated quantum dot type – MBB@SiO2. MBB@SiO2 comprises perovskite quantum dots MA3Bi2Br9 and silica formed on the surface of MA3Bi2Br9. The details of MBB@SiO2 are as described above and will not be repeated here for brevity.

[0066] The hydrogel resin provided in this embodiment of the invention exhibits good stability with MBB@SiO2. This stability is manifested in the fact that the hydrogel resin and MBB@SiO2 do not react at room temperature, and the hydrogel resin does not affect the fluorescence properties and luminescence stability of MBB@SiO2. Furthermore, considering the applications of quantum dot hydrogels in anti-counterfeiting and information storage technologies, the hydrogel resin is selected from colorless and transparent hydrogel resins. In some embodiments, the hydrogel resin is selected from at least one of polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate, and carboxymethyl cellulose methacrylate. For example, the hydrogel resin is selected from polyethylene glycol diacrylate (PEGDA) with a number average molecular weight of approximately 700.

[0067] In this embodiment of the invention, the mass ratio of quantum dot material to hydrogel resin is 0 to 1:100, and the mass of quantum dot material is not zero. When the mass ratio is within this range, the quantum dot hydrogel exhibits high fluorescence intensity and good mechanical properties. For example, the mass ratio of quantum dot material to hydrogel resin can be 0.01:100, 0.05:100, 0.08:100, 0.10:100, 0.15:100, 0.18:100, 0.20:100, 0.25:100, 0.28:100, 0.30:100, 0.35:100, 0.38:100, 0.40:100, 0.45:100, 0.48:100, 0.40:100, 0.50:100, 0.60:100, 0.70:100, 0.80:100, 0.90:100, 1.0:100, etc.

[0068] In some embodiments, MBB@SiO2 can be prepared by the following steps:

[0069] (1) Mix the silane coupling agent with the MA3Bi2Br9 quantum dot solution and add water to form an emulsion.

[0070] In this step, the silane coupling agent is a trimethoxysilane with a terminal active functional group. The active functional group referred to here is a reactive group capable of binding to MA3Bi2Br9 quantum dots, including but not limited to amino, thiol, and carboxyl groups. For example, the silane coupling agent is at least one of 3-aminopropyltrimethoxysilane (APS), γ-aminoethylaminopropyltrimethoxysilane, and m-aminophenyltrimethoxysilane, but is not limited to these.

[0071] In this embodiment of the invention, the MA3Bi2Br9 quantum dot solution is a solution formed by MA3Bi2Br9 quantum dots in a nonpolar or low-polarity reagent, also known as an oil-soluble solution of MA3Bi2Br9 quantum dots. The reagent used to disperse the MA3Bi2Br9 quantum dots needs to be able to effectively disperse them, and also has minimal impact on the optical properties and quantum yield of the MA3Bi2Br9 quantum dots. In this embodiment of the invention, at least one of alkane reagents and organic carboxylic acid reagents is preferably selected as the dispersing agent for MA3Bi2Br9 quantum dots. For example, the MA3Bi2Br9 quantum dot solution is a mixed solution formed by dispersing MA3Bi2Br9 quantum dots in a mixture of n-octane and oleic acid. In this case, the MA3Bi2Br9 quantum dots can maintain their excellent optical properties and quantum dot yield, and exhibit luminescence stability.

[0072] In some embodiments, in the step of mixing the silane coupling agent with the MA3Bi2Br9 quantum dot solution, the two are mixed in a volume ratio of 1 to 10:500. This ensures that the silane coupling agent and MA3Bi2Br9 quantum dots are mixed in a suitable ratio, which facilitates the full binding of the silane coupling agent to the surface of the MA3Bi2Br9 quantum dots, thereby improving the surface defects of the MA3Bi2Br9 quantum dots. Furthermore, by controlling the content of both, the particle size of the resulting MBB@SiO2 can be effectively controlled, allowing MBB@SiO2 to maintain good quantum effects and fluorescence properties even after silica coating. For example, the volume ratio of the silane coupling agent to the MA3Bi2Br9 quantum dot solution can be 3:500, 1:125, 1:100, 3:2500, 7:500, 2:125, etc.

[0073] A silane coupling agent is mixed with an MA3Bi2Br9 quantum dot solution, and then water is added to form an emulsion. The amount of water added is sufficient to form an emulsion. In some embodiments, 80% to 120% of the total volume of the mixed solution obtained by mixing the silane coupling agent and the MA3Bi2Br9 quantum dot solution is added to obtain an emulsion. For example, an equal volume of water as the mixed solution is added to obtain an emulsion.

[0074] (2) The emulsion was heated and refluxed until it broke down and separated into layers. The lower aqueous layer was collected and dried to obtain MBB@SiO2.

[0075] In this step, silane coupling agent is bonded to the surface of MA3Bi2Br9 quantum dots by heating and refluxing, and reacts to form silicon dioxide. In some embodiments, the heating and refluxing temperature is 100-120°C, and the heating and refluxing time is 3-12 hours, which fully realizes the bonding of silane coupling agent to the surface of MA3Bi2Br9 quantum dots and fully forms silicon dioxide on the surface of MA3Bi2Br9 quantum dots, thus obtaining water-soluble MBB@SiO2. Taking 3-aminopropyltrimethoxysilane as the silane coupling agent and a mixed solution of MA3Bi2Br9 quantum dots in n-octane and oleic acid as an example, heating and refluxing at 105°C for 6 hours at a temperature between the boiling point of n-octane and water causes the emulsion to break down and separate into layers.

[0076] The lower aqueous layer, containing MBB@SiO2, is collected. The aqueous solution is then dried to obtain MBB@SiO2. In some embodiments, freeze-drying is used, which improves drying efficiency and helps retain the fluorescence properties of MBB@SiO2. In one embodiment, the collected lower aqueous layer is freeze-dried for 2–3 days to obtain MBB@SiO2.

[0077] It should be understood that the above method is a specific implementation of preparing MBB@SiO2 and is not intended to limit the preparation method of MBB@SiO2.

[0078] In the step of mixing quantum dot material, hydrogel resin, photoinitiator, and water in this embodiment of the invention, the photoinitiator is used to crosslink the hydrogel resin under ultraviolet conditions to form a network structure. In some embodiments, to avoid unintentionally triggering the reaction by the photoinitiator, MBB@SiO2, hydrogel resin, and water can be mixed first, and then the photoinitiator can be added. For example, MBB@SiO2 is first dispersed in water, then the hydrogel resin is added and mixed evenly, and finally the photoinitiator is added.

[0079] In some embodiments, the mass ratio of hydrogel resin to water is 1:0 to 1, and the mass of water is not zero. A mass ratio within this range is beneficial for forming hydrogel materials and for imparting excellent shaping properties to MBB@SiO2. If the water content is too high, the formed quantum dot hydrogel may deform due to water evaporation, thus affecting the plasticity of the quantum dots. For example, the mass ratio of hydrogel resin to water can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, etc.

[0080] The photoinitiator used in this invention has the function of initiating a photoreaction under ultraviolet light. Considering the confidentiality requirements of anti-counterfeiting and storage materials, a photoinitiator with high transparency is selected. In some embodiments, the photoinitiator is selected from at least one of lithium phenyl (2,4,6-trimethylbenzoyl)phosphate and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone. For example, when the hydrogel resin is polyethylene glycol diacrylate, the photoinitiator is lithium phenyl (2,4,6-trimethylbenzoyl)phosphate (LAP).

[0081] In some embodiments, the mass ratio of photoinitiator to hydrogel resin is 1 to 5:1250. This ratio effectively initiates photopolymerization while minimizing photoinitiator residue, thus maximizing its effectiveness. Especially when the photoinitiator is not completely colorless and transparent, residual photoinitiator may compromise the security properties of the quantum dot hydrogel material when used as an anti-counterfeiting or storage material. Exemplary examples include mass ratios of 1:1250, 2:1250, 3:1250, 4:1250, and 5:1250.

[0082] S21. Under ultraviolet light, a curing reaction occurs to form a quantum dot hydrogel.

[0083] In this step, under ultraviolet (UV) conditions, the photoinitiator is excited to react, and the hydrogel resin crosslinks to form a network structure. In some embodiments, the UV conditions include: an excitation wavelength of 385±20 nm and a laser power of 40–60 W. Under these conditions, the hydrogel crosslinks and cures to obtain good hardness and maintain the shape and mechanical properties of the molded product. In some embodiments, the curing time is 1–10 min.

[0084] For example, when the hydrogel resin is polyethylene glycol diacrylate and the photoinitiator is lithium phenyl (2,4,6-trimethylbenzoyl) phosphate (LAP), a quantum dot hydrogel material is formed by acting at an excitation wavelength of 365 nm and a laser power of 65 W for 1 min.

[0085] The present invention provides a method for preparing quantum dot hydrogels, using quantum dot materials, hydrogel resin, photoinitiator, and water as raw materials. Under ultraviolet conditions, the hydrogel resin undergoes cross-linking, and the resulting cross-linked structure binds the quantum dot material within it, endowing the quantum dot material with shape plasticity. This method is simple to operate and easy to control, which is beneficial for enabling the application of quantum dot materials in various products with shape requirements, especially meeting the product requirements of perovskite quantum dots in fields such as anti-counterfeiting, information storage, and encryption.

[0086] This invention also provides applications of quantum dot hydrogels in anti-counterfeiting, encryption, and information storage. For example, quantum dot hydrogels are prepared for use as anti-counterfeiting or storage materials. The applications of quantum dot hydrogels in these fields are described below with examples.

[0087] This invention provides a 3D printing method for anti-counterfeiting or storage products, comprising the following steps:

[0088] S10. A mixture is prepared by mixing quantum dot material, hydrogel resin, photoinitiator and water, wherein the mixture includes a first mixture in which the mass percentage of quantum dot material is not 0.

[0089] In this step, the quantum dot material is a coated quantum dot, which includes perovskite quantum dots MA3Bi2Br9 and silicon dioxide formed on the surface of MA3Bi2Br9. In this embodiment of the invention, in the step of mixing quantum dot material, hydrogel resin, photoinitiator and water to obtain a first mixture, the preparation of the first mixture, as well as the selection and content or ratio of each raw material, can be referred to step S11 above, and will not be repeated here for the sake of brevity.

[0090] In some embodiments, this step further includes mixing the hydrogel resin, photoinitiator, and water to obtain a second mixture. In this case, the second mixture does not contain quantum dot material. The preparation of the second mixture, as well as the selection of the hydrogel resin and photoinitiator, and the content or ratio of the hydrogel resin, photoinitiator, and water, can be referred to step S11 above, except that the second mixture does not contain quantum dot material.

[0091] S30. The first mixture is formed into a first liquid film by a 3D printer and then cured by ultraviolet light to obtain a functional layer.

[0092] This step is used to prepare a film layer with anti-counterfeiting markings, stored information, or encrypted information. Since this film layer achieves functions such as anti-counterfeiting, storage, and encryption through quantum dot materials, it is called a functional layer. A first mixture is printed using a 3D printer to form a first liquid film. In some embodiments, the first mixture is dropwise added to the printer platform to form the first liquid film. Under ultraviolet conditions, a photoinitiator initiates cross-linking and curing of the hydrogel resin, binding the quantum dot material within the cross-linked network structure formed by the hydrogel resin, thus obtaining the cured functional layer. By controlling the content of quantum dot material in the functional layer and setting the pattern, the anti-counterfeiting, information storage, or encryption functions of the functional layer can be achieved.

[0093] In some embodiments, the functional layer can be a single-layer structure. For example, when 3D printing a label, the functional layer is a single-layer structure, and in this case, the preparation of a single-layer functional layer can be achieved by performing step S30 once. In some embodiments, the functional layer can be a multilayer structure. In this case, multiple steps S30 can be performed to prepare multilayer films for the purpose of anti-counterfeiting or information storage. In one embodiment, the functional layer includes n quantum dot hydrogel layers stacked together along a direction perpendicular to the surface of the functional layer, and the quantum dot content in the first mixture used to prepare each quantum dot hydrogel layer is the same or different, where n is a natural number ≥ 1. It should be understood that when preparing n films stacked together along a direction perpendicular to the surface of the functional layer, the pattern of each film layer can be set by adjusting the content of quantum dot material in each quantum dot hydrogel layer.

[0094] In some embodiments, among the n quantum dot hydrogel layers, at least one group of adjacent quantum dot hydrogel layers is provided with a hydrogel resin layer, which is prepared from a second mixture. In one embodiment, a hydrogel resin layer is provided between each group of adjacent quantum dot hydrogel layers, i.e., the functional layer forms an alternating stacked structure of quantum dot hydrogel layer-hydrogel resin layer-quantum dot hydrogel layer.

[0095] In some embodiments, the method for preparing the hydrogel resin layer includes: printing a second mixture onto the surface of a quantum dot hydrogel layer using a 3D printer, and then curing the hydrogel resin layer with ultraviolet light.

[0096] In this step, a second mixture without quantum dot materials is 3D printed to form a liquid film. Under ultraviolet light, a photoinitiator induces cross-linking and curing of the hydrogel resin, resulting in a cured hydrogel resin layer. Because the hydrogel resin layer does not contain quantum dot materials, it does not possess fluorescent properties.

[0097] In some embodiments, prior to step S30, the method further includes:

[0098] S20. The second mixture is printed using a 3D printer to form a second liquid film, which is then cured under ultraviolet light to prepare a first base layer. At this point, a functional layer is formed on the surface of the first base layer.

[0099] In this step, a second mixture without quantum dot material is printed using a 3D printer to form a second liquid film. In some embodiments, the second mixture is formed by dropping it onto a printer platform. Curing under ultraviolet light yields a cured hydrogel resin layer, which serves as the first substrate layer. Because the first substrate layer does not contain quantum dot material, it does not possess fluorescent properties.

[0100] In one embodiment, the first substrate layer consists of a single hydrogel resin layer. In another embodiment, the first substrate layer comprises multiple stacked hydrogel resin layers. In this case, multiple hydrogel resin layers can be prepared using the same method to achieve the required thickness of the first substrate layer. In one embodiment, the preparation of the first substrate layer includes: printing a second mixture using a 3D printer to form a second liquid film, followed by UV curing to form a first hydrogel resin layer; repeating this step sequentially printing a second hydrogel resin layer, and if necessary, a third hydrogel resin layer, ... until the thickness of the first substrate layer meets the requirements.

[0101] In some embodiments, after step S30, the method further includes:

[0102] S40. The second mixture is formed on the surface of the functional layer by a 3D printer and cured by ultraviolet light to prepare the second base layer.

[0103] In this step, a second mixture without quantum dot materials is formed on the surface of the functional layer to form a third liquid film. Under ultraviolet light, a photoinitiator initiates cross-linking and curing of the hydrogel resin, resulting in a cured hydrogel resin layer, which serves as the second substrate layer. Since the second substrate layer does not contain quantum dot materials, it does not possess fluorescent properties.

[0104] In one embodiment, the second substrate layer consists of a single hydrogel resin layer. In another embodiment, the second substrate layer comprises multiple stacked hydrogel resin layers. In this case, multiple hydrogel resin layers can be prepared using the same method to achieve the required thickness of the second substrate layer. In one embodiment, the preparation of the second substrate layer includes: printing a second mixture using a 3D printer to form a third liquid film, followed by UV curing to form a first hydrogel resin layer; repeating this step sequentially printing a second hydrogel resin layer, and if necessary, a third hydrogel resin layer, ... until the thickness of the second substrate layer meets the requirements.

[0105] In some embodiments, 3D printing includes steps S20 and S40, namely, preparing a first substrate layer and a second substrate layer on two surfaces of the functional layer respectively. The first substrate layer and the second substrate layer are respectively disposed on the two surfaces of the functional layer to form a sandwich structure, which is used to cover the information of the functional layer to prevent the information of the functional layer from being easily identified and thus reducing the anti-counterfeiting or confidentiality performance.

[0106] The 3D printing method provided in this invention uses hydrogel resin without perovskite quantum dots as the raw material to prepare the substrate layer, and uses silica-coated perovskite quantum dots and hydrogel resin as raw materials to prepare the functional layer, thus obtaining a sandwich structure. This method allows perovskite quantum dots to be embedded in a curable hydrogel resin, thereby endowing the perovskite quantum dots with excellent molding capabilities. This enables the 3D printing of anti-counterfeit or storage items using perovskite quantum dots as encrypted or stored information.

[0107] The following explanation uses SiO2-coated bismuth-based perovskite (MA3Bi2Br9) quantum dots (MBB@SiO2) as an example.

[0108] Example 1

[0109] A method for preparing quantum dot hydrogels, comprising:

[0110] (1) Weigh 1g of PEGDA and add it to 1mL of water. Shake, sonicate, and mix evenly to obtain a mixed solution. Weigh 2.4mg of LAP and add it to the above mixed solution. Dissolve by sonication to obtain a hydrogel resin without MBB@SiO2.

[0111] (2) Weigh 6 mg of MBB@SiO2 solid into a glass bottle, add 1 mL of water, shake, and sonicate to disperse evenly to obtain a quantum dot solution. Weigh 1 g of PEGDA and add it to the quantum dot solution, shake, sonicate, and mix evenly to obtain a mixed solution. Weigh 2.4 mg of LAP and add it to the above mixed solution, and sonicate to dissolve to obtain a quantum dot hydrogel resin with an MBB@SiO2 weight percentage of 0.3%. Prepare quantum dot hydrogel resins with MBB@SiO2 weight percentages of 0.1%, 0.2%, 0.4%, and 0.5% respectively using the same method, and store the five quantum dot hydrogel resins in the dark.

[0112] (3) Take 1 mL of each of the five quantum dot hydrogel resins and the non-quantum dot hydrogel resin, and transfer them into a silicone mold with a thickness of about 0.3 mm. The silicone mold is clamped between two glass plates with a thickness of 2.1 mm. Then place it under ultraviolet light (365 nm) for 1 minute (about 7 cm away from the lamp head). After the cross-linked hydrogel sheets have cooled to room temperature, take them out to obtain five quantum dot hydrogel sheets and one hydrogel sheet.

[0113] Samples of different sizes and shapes were cut from quantum dot hydrogel sheets and hydrogel sheets for experimental characterization:

[0114] (4) Five quantum dot hydrogel sheets and one hydrogel sheet were cut into quantum dot hydrogel discs and hydrogel discs (hereinafter collectively referred to as discs). The light absorption intensity diagram of the six discs and the photograph of the six discs after being covered on the surface of the Sun Yat-sen University emblem are shown in the figure. Figure 1 As shown; optical performance results are as follows Figure 2 and Figure 3 As shown, where, Figure 2 This is a fluorescence intensity map. Figure 3 This is a fluorescence lifetime diagram.

[0115] Depend on Figure 1 As can be seen, when the MBB@SiO2 doping content is between 0 and 0.5 wt%, the obtained samples are all colorless and transparent. This demonstrates that when using MBB@SiO2 as a storage medium, the quantum dot hydrogel does not interfere with the color of the sample pattern or cause leakage.

[0116] Depend on Figure 2 As can be seen, the fluorescence intensity of the quantum dot hydrogel increases with the increase of MBB@SiO2 doping, and almost reaches saturation at a doping concentration of 0.26 wt%. This means that better fluorescence intensity can be obtained by controlling the MBB@SiO2 doping amount, while also achieving cost savings.

[0117] Depend on Figure 3 As can be seen, the fluorescence lifetime of the quantum dot hydrogel with added MBB@SiO2 is 5.2 ns (an increase compared to 3.9 ns without added PEGDA), but the doping concentration of MBB@SiO2 has almost no effect on the fluorescence lifetime.

[0118] (5) Quantum dot hydrogel sheets and hydrogel sheets were cut into dumbbell-shaped hydrogels, and the mechanical properties were characterized as follows: Figure 4 As shown.

[0119] Depend on Figure 4 It is evident that changing the amount of MBB@SiO2 incorporated does not alter the tensile modulus and elongation at break of the dumbbell-shaped hydrogel, indicating that the incorporation of MBB@SiO2 has no effect on the mechanical properties of the gel.

[0120] Example 2

[0121] A method for 3D printing quantum dot hydrogels, comprising:

[0122] (1) Weigh 6 mg of MBB@SiO2 solid into a glass bottle, add 1 mL of water, shake, and sonicate to disperse evenly to obtain a quantum dot solution. Weigh 1 g of PEGDA and add it to the quantum dot solution, shake, sonicate, and mix evenly to obtain a mixed solution. Weigh 2.4 mg of LAP and add it to the above mixed solution, sonicate to dissolve, and obtain a quantum dot hydrogel resin with an MBB@SiO2 weight percentage of 0.3%, which should be stored in the dark.

[0123] (2) Add 1 mL of quantum dot hydrogel to the 3D printer platform, and set the light intensity to 30 mW / cm². 3 An exposure time of 2 seconds was used to print a quantum dot hydrogel with a thickness of 0.3 mm. The results showed that MBB@SiO2 embedded in photocurable water-soluble polyethylene glycol diacrylate (PEGDA) resin exhibited excellent molding ability.

[0124] Example 3

[0125] A multi-layer 3D printing method, reference Figure 5 ,include:

[0126] Add 50 μL of hydrogel resin (without MBB@SiO2) to the printer platform, and set the light intensity to 15 mW / cm². 3 The exposure time was 2 seconds, and the thickness was 20 μm. Hydrogel resin was added and the printing was repeated, resulting in a total of 50 hydrogel resin layers.

[0127] The hydrogel resin tank was cleaned with deionized water and dried. Then, 50 μL of MBB@SiO2-doped hydrogel resin with a concentration of 0.3 wt% was added, and the light intensity was set to 15 mW / cm². 3 The exposure time was 2 seconds, the thickness was 20 μm, and according to... Figure 6 The provided slice model was used to repeatedly print three layers of quantum dot hydrogel resin.

[0128] Rinse the hydrogel resin tank again with deionized water, dry it, and replace it with hydrogel resin (without MBB@SiO2). Set the light intensity to 15 mW / cm². 3 The exposure time was 2 seconds, each layer was 20 μm, and a total of 10 layers were printed.

[0129] The 3D printing method provided in Example 3 forms a quantum dot hydrogel layer containing stored or encrypted information in the intermediate layer. The two surfaces of the intermediate layer are each covered with a hydrogel resin layer, forming a sandwich structure that protects the stored or encrypted information in the intermediate layer. Z-axis tomography is performed using a confocal microscope to read the information, and decryption is performed using the GBK character set to obtain the encrypted information.

[0130] Example 4

[0131] A method for printing 3D labels, comprising:

[0132] A square base made of hydrogel resin was prepared by 3D printing using PEGDA.

[0133] 50 μL of a hydrogel resin with an MBB@SiO2 doping concentration of 0.3 wt% was used, and the light intensity was set to 15 mW / cm².3 Two-dimensional printed samples of the Sun Yat-sen University emblem and a paper-cut horse badge were printed on a hydrogel resin square base with an exposure time of 2 seconds and a thickness of 20 μm. The resulting two-dimensional printed samples of the Sun Yat-sen University emblem and paper-cut horse badge are shown below. Figure 7 As shown, from left to right: bright-field micrograph of the Sun Yat-sen University emblem, fluorescent micrograph of the Sun Yat-sen University emblem, bright-field micrograph of the window-patterned horse badge, and fluorescent micrograph of the window-patterned horse badge. As can be seen from the images, under the fluorescence microscope, the square base is not visible; only the badge content emits blue light. This demonstrates that 3D printing using quantum dot hydrogel can achieve anti-counterfeiting properties for two-dimensional items.

[0134] Example 5

[0135] A method for printing 3D labels, comprising:

[0136] PEGDA was used for 3D printing to prepare hydrogel resin substrates.

[0137] 50 μL of a hydrogel resin with an MBB@SiO2 doping concentration of 0.3 wt% was used, and the light intensity was set to 15 mW / cm². 3 A beluga whale relief was printed on a hydrogel resin substrate with an exposure time of 2 seconds and a thickness of 20 μm. The SEM image of the hydrogel microstructure of the beluga whale relief is shown below. Figure 8 As shown in the figure, the hydrogel structure is relatively dense in the SEM images, but some tiny patterns appear on some flat surfaces. These patterns may originate from the evaporation of water from the resin. A photo frame was also embossed using pure PEGDA. The confocal Z-axis tomographic reconstruction images of the 3D printed sample at different angles are shown below. Figure 9 As shown in the figure, the frame is not visible under a confocal microscope, proving that the method provided in this embodiment of the invention achieves anti-counterfeiting for three-dimensional objects.

[0138] Example 6

[0139] A method for printing 3D labels, comprising:

[0140] 50 μL of PEGDA hydrogel resin (without MBB@SiO2) was dropped onto the printer platform, and the light intensity was set to 15 mW / cm². 3 The first hydrogel resin substrate was prepared by exposing the substrate for 2 seconds.

[0141] The hydrogel resin tank was cleaned with deionized water and dried. Then, 50 μL of MBB@SiO2-doped hydrogel resin with a concentration of 0.3 wt% was added, and the light intensity was set to 15 mW / cm². 3 An exposure time of 2 seconds and a thickness of 20 μm were used to print a quantum dot hydrogel resin layer with QR code information.

[0142] Rinse the hydrogel resin tank again with deionized water, dry it, and then replace it with PEGDA hydrogel resin (without MBB@SiO2). Set the light intensity to 15mW / cm². 3 The second hydrogel resin substrate was prepared by exposing the substrate for 2 seconds.

[0143] This results in a set of 3D printed parts with encrypted two-dimensional information, such as... Figure 10 As shown in the figure, the sample appears colorless and transparent under natural light, but the stored information (QR code) is clearly visible under a 365nm ultraviolet lamp. To facilitate the recognition of the QR code by a smartphone, the stored QR code was imaged separately using a fluorescence microscope.

[0144] Example 7

[0145] The inscription "School of Materials Science and Engineering, Sun Yat-sen University" was converted to GBK binary code using the same method as in Example 3, employing a two-dimensional 8x8 information matrix printed using a single droplet. This information can be identified using a fluorescence microscope and subsequently decoded using the GBK character set, as shown below. Figure 11 As shown, 0 and 1 represent the fluorescence signal intensity at the location, where 0 indicates that the film layer does not contain quantum dot material at that location and there is no fluorescence signal; 1 indicates that the film layer contains quantum dot material at that location and produces a fluorescence signal with an intensity of 1.

[0146] Example 8

[0147] The inscription "School of Materials Science and Engineering, Sun Yat-sen University" was converted to GBK quaternary code. Using the same method as in Example 3, three-dimensional information matrices of varying thicknesses were 3D printed. In this case, an 8x8 matrix could represent twice the amount of information. This information could be identified using a fluorescence microscope by observing the different fluorescence intensities in regions of varying thicknesses, thus revealing the three-dimensional information, which was then decoded. Figure 12 As shown, 0, 1, 2, and 3 represent the fluorescence signal intensity at each location. 0 indicates that none of the three film layers contain quantum dot material at that location, resulting in no fluorescence signal. 1 indicates that one film layer contains quantum dot material at that location, producing a fluorescence signal with an intensity of 1. 2 indicates that two film layers contain quantum dot material at that location, producing a fluorescence signal with an intensity of 2. 3 indicates that all three film layers contain quantum dot material at that location, producing a fluorescence signal with an intensity of 3.

[0148] Example 9

[0149] The information "Sun Yat-sen University" was converted to GBK quaternary code and then 3D printed using the following method:

[0150] PEGDA hydrogel resin (without MBB@SiO2) was dropped onto the printer platform to prepare the first hydrogel resin substrate.

[0151] Clean the hydrogel resin tank with deionized water, dry it, add MBB@SiO2 hydrogel resin, photocur, and print a quantum dot hydrogel resin film; replace with PEGDA hydrogel resin (without MBB@SiO2) to prepare a hydrogel resin film on the quantum dot hydrogel resin film, repeat this step to prepare a three-layer hydrogel resin film.

[0152] The hydrogel resin tank was rinsed again with deionized water and dried. Then, the PEGDA hydrogel resin (without MBB@SiO2) was replaced to prepare the second hydrogel resin substrate.

[0153] This embodiment prints a three-dimensional 8x8 information matrix of the same thickness at locations at different spatial heights. At this time, as... Figure 13 As shown, under a fluorescence microscope, all fluorescent areas, due to their uniform thickness, exhibit consistent fluorescence intensity, making them indistinguishable and leading to the identification of incorrect information. Only a confocal microscope can distinguish information areas located at different spatial heights and decode the correct information. Therefore, the 3D printing method provided in this application adds a dimension to information encryption, enhancing information security.

[0154] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A quantum dot hydrogel, characterized in that, The invention includes a hydrogel resin and a quantum dot material dispersed in the hydrogel resin, wherein the quantum dot material is a coated quantum dot, the coated quantum dot includes perovskite quantum dot MA3Bi2Br9 and silica formed on the surface of the MA3Bi2Br9, the mass ratio of the quantum dot material to the hydrogel resin is 0 to 1:100, and the mass of the quantum dot material is not 0.

2. The quantum dot hydrogel as described in claim 1, characterized in that, The hydrogel resin is selected from at least one of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, and carboxymethyl cellulose methacrylate.

3. A method for preparing quantum dot hydrogels, characterized in that, Includes the following steps: A mixture of quantum dot material, hydrogel resin, photoinitiator, and water is prepared and then cured under ultraviolet light to form a quantum dot hydrogel. The quantum dot material is a coated quantum dot, comprising perovskite quantum dots MA3Bi2Br9 and silica formed on the surface of the MA3Bi2Br9. The mass ratio of the quantum dot material to the hydrogel resin is 0 to 1:100, and the mass of the quantum dot material is not 0. The mass ratio of the hydrogel resin to the water is 1:0 to 1, and the mass of the water is not 0. The mass ratio of the photoinitiator to the hydrogel resin is 1 to 5:1250.

4. The preparation method according to claim 3, characterized in that, The hydrogel resin is selected from at least one of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, and carboxymethyl cellulose methacrylate; and / or The photoinitiator is selected from at least one of phenyl (2,4,6-trimethylbenzoyl) lithium phosphate and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone.

5. The preparation method according to claim 3 or 4, characterized in that, The ultraviolet conditions include: an excitation wavelength of 385±20nm and a laser power of 40-60W / cm². 3 ; and / or The curing process takes 1 to 10 minutes.

6. The application of the quantum dot hydrogel as described in any one of claims 1-2 or the quantum dot hydrogel prepared by the method described in any one of claims 3-5 in the fields of anti-counterfeiting, encryption and information storage.

7. A 3D printing method, characterized in that, Includes the following steps: A first mixture is obtained by mixing quantum dot material, hydrogel resin, photoinitiator and water. The quantum dot material is a coated quantum dot, which includes perovskite quantum dot MA3Bi2Br9 and silica formed on the surface of MA3Bi2Br9. The mass ratio of the quantum dot material to the hydrogel resin is 0 to 1:100, and the mass of the quantum dot material is not 0. The first mixture is printed using a 3D printer to form a first liquid film, and then a functional layer is prepared by UV curing.

8. The 3D printing method as described in claim 7, characterized in that, The method further includes: A second mixture is obtained by mixing hydrogel resin, photoinitiator and water; Before preparing the functional layer, the second mixture is printed by a 3D printer to form a second liquid film, and then cured by ultraviolet light to prepare a first base layer; and the functional layer is formed on the surface of the first base layer.

9. The 3D printing method as described in claim 8, characterized in that, The first substrate layer consists of a single layer of hydrogel resin, or the first substrate layer comprises multiple stacked hydrogel resin layers.

10. The 3D printing method according to any one of claims 8-9, characterized in that, The method further includes: forming the second mixture on the surface of the functional layer using a 3D printer, and then preparing a second base layer by UV curing.

11. The 3D printing method as described in claim 10, characterized in that, The second base layer consists of a single layer of hydrogel resin, or the second base layer comprises multiple stacked hydrogel resin layers.

12. The 3D printing method according to any one of claims 7-9, characterized in that, The functional layer comprises n quantum dot hydrogel layers stacked together along a direction perpendicular to the surface of the functional layer, and the quantum dot content in the first mixture used to prepare each quantum dot hydrogel layer may be the same or different, where n is a natural number ≥1.

13. The 3D printing method as described in claim 12, characterized in that, A hydrogel resin layer is disposed between at least one set of adjacent quantum dot hydrogel layers.

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