Quantum dot solution-based life signal combined coding method and application

Abstract

The invention provides a quantum dot solution-based life signal combination coding method, which comprises the following steps: S1, preparing transition metal element doped core-shell quantum dot solutions with different lives according to different doping amounts; s2, combining the quantum dot solutions with different service lives according to different proportions to obtain quantum dot solutions with different levels of service life codes; performing hierarchical regulation and control on the service life of the quantum dot solutions with different levels of service life codes by using a fluorescence service life imaging microscope and a phasor analysis method on the basis of a vector rule, so as to realize accurate design, prediction and analysis; s3, quantum dot solutions of different levels of life codes serve as printing ink, and clusters at different positions appear in a phasor diagram by printing an encrypted pattern; and S4, another kind of quantum dot ink is used as a key to be printed on the encrypted pattern in the S3 in an overlapped mode, the position of a cluster in the phasor diagram changes, and real encrypted information is obtained by decoding the position of the key.

Description

Technical Field

[0001] The invention relates to the field of nano material preparation, and in particular to quantum dot solutions with different lifetimes, a phase analysis method and a lifetime signal combination coding method thereof. Background Art

[0002] The lifetime (τ) of a fluorescent substance refers to the time required for a photon to decay to 1 / e of its original intensity. Unlike fluorescence intensity, fluorescence lifetime is an intrinsic property of the substance and is not affected by concentration, excitation intensity, and other factors. Therefore, fluorescence lifetime imaging (FLI) has become a widely used technique. In practical applications, regardless of the type of fluorescence lifetime microscope used, the processing of fluorescence lifetime data is a key step. Traditionally, the determination of fluorescence decay curves requires least squares fitting analysis of each pixel on the image. This method requires the selection of a suitable fitting model (such as single, double, triple exponential decay or non-exponential decay) in data analysis, and a large number of photons (usually >1000) must be collected to achieve effective fitting. These limitations make data analysis of fluorescence lifetime imaging very time-consuming.

[0003] The phasor analysis method is a method to simplify the lifetime information of the original fluorescence lifetime imaging diagram, which can convert the decay signal of each pixel in the image into a point on the phasor diagram. This conversion relationship is presented on the phasor diagram as a semicircular curve with a radius of 0.5 and a center of (G=0.5, S=0), which is called a semicircle. In the phasor semicircle, the pixels of the single exponential decay behavior are located on the semicircle, and the pixels of the multi-exponential decay behavior are located inside the semicircle. Multiple pixels with similar fluorescence decay characteristics are located in similar areas in the phasor diagram, forming a "phasor cluster", which is convenient for data visualization and cluster analysis. An important feature of the phasor diagram is that the phasor endpoints corresponding to the multi-exponential decay process are located in the set composed of the lifetime phasor endpoints corresponding to each single exponential decay component, and the distance from the endpoint is inversely proportional to the intensity of its contribution. These features play an important role in quantifying, visualizing and clustering fluorescence lifetime data.

[0004] At present, the methods of fluorescence lifetime signal processing based on phasor analysis mainly focus on the unmixing analysis of complex fluorescence lifetime signals in biological samples. However, the current problems are: the difficulty in accurately designing, predicting and analyzing complex fluorescence lifetime combination signals, poor signal analysis accuracy and low efficiency, etc. Summary of the invention

[0005] Therefore, technicians in this field are committed to developing a method that can accurately design, predict and analyze complex lifetime combination signals in order to obtain highly stable, fast and intuitive lifetime combination signals.

[0006] To achieve the above object, the present invention provides a lifetime signal combination encoding method based on a quantum dot solution, the encoding method comprising the following steps:

[0007] S1. preparing core-shell quantum dot solutions doped with transition metal elements of different lifetimes according to different doping amounts;

[0008] S2. Quantum dot solutions with different lifetimes are combined in different proportions to obtain quantum dot solutions with lifetime codes of different levels; quantum dot solutions with lifetime codes of different levels are regulated by fluorescence lifetime imaging microscopy and phase analysis based on the vector law to achieve precise design, prediction and analysis;

[0009] S3, using quantum dot solutions with different levels of lifetime coding as printing ink to print encrypted patterns, and clusters at different positions appear in the phasor diagram;

[0010] S4, use another quantum dot ink as a key, superimpose it on the encryption pattern of S3, the cluster position in the phasor diagram changes, and the real encrypted information is obtained by decoding the position of the key.

[0011] In step S4, the position cluster of the "key" in the phasor diagram and the cluster position of the quantum dot solution printing ink with different levels of lifetime coding in S3 in the phasor diagram follow the phasor addition law.

[0012] In step S1, the transition metal element doped core-shell quantum dots include at least one of zinc selenide / zinc sulfide core-shell quantum dots, manganese sulfide / zinc sulfide core-shell quantum dots, cadmium selenide / zinc sulfide core-shell quantum dots, and indium phosphide / zinc sulfide core-shell quantum dots.

[0013] In step S1, the transition metal element includes one or more of manganese, copper, zinc, silver, and cobalt.

[0014] In step S1, the core-shell quantum dots doped with transition metal elements of different lifetimes are large Stokes shift quantum dots of different lifetimes, and the lifetimes vary from microseconds to nearly milliseconds.

[0015] In step S2, the quantum dots with different lifetimes have the same photon number under the same excitation intensity, and solutions with different lifetimes but the same photon number are mixed in different volume proportions. According to the vector addition principle in the semicompass, the positions of the quantum dot solutions with different lifetimes on the semicompass are designed and predicted.

[0016] Step S1 includes the following steps:

[0017] S11, adding a zinc source and a manganese source in different proportions to a solvent to form a mixed solution, degassing, adding a selenium precursor solution after heating, and then adding a zinc precursor solution to obtain a Mn:ZnSe core solution with different manganese ion doping amounts;

[0018] S12. Degas the Mn:ZnSe core solutions with different manganese ion doping amounts obtained in step S11, add Zn(OA)2-OT mixed precursor solutions after heating, and keep warm for a period of time to obtain Mn:ZnSe / ZnS core-shell structure quantum dot solutions with different manganese ion doping amounts; that is, core-shell quantum dot solutions doped with transition metal elements with different lifespans.

[0019] As an embodiment of the present invention, the ratio of zinc source to manganese source is 40-53:1-3, 10-15:1-3, 4-8:1-3, 1-5:1-3 and 1-3:1-3, to prepare transition metal element-doped core-shell quantum dots with different lifetimes.

[0020] In S11, in the mixed solution, the concentration of the zinc source is 0.01-0.03 mol / L, and the concentration of the manganese source is 0.0005-0.001 mol / L.

[0021] In S11, the zinc source includes at least one of zinc acetate, zinc stearate, zinc acetate and zinc sulfate; the manganese source includes at least one of manganese oxide, manganese stearate, manganese acetate and manganese dichloride.

[0022] In S11, the selenium precursor is prepared by the following method: selenium powder is ultrasonically dispersed in a solvent (the solvent may be n-octadecene and / or oleylamine) to form a selenium solution, wherein the concentration of the selenium solution is 0.01-0.03 g / L.

[0023] In S11, the zinc and sulfur precursors are prepared by the following method: a zinc source is added to a solvent for degassing, the temperature is raised to 300-305° C. and then kept warm for 10-30 minutes, and the temperature is lowered to 130-160° C. and then a sulfur source is added; wherein the sulfur source is at least one of n-octyl mercaptan, thioacetamide and sulfur powder.

[0024] In S11, the solvent is a mixed solution of n-octadecene and oleic acid, and the volume ratio of n-octadecene to oleic acid is 0.5-1.5:0.5-1.5.

[0025] As an embodiment of the present invention, step S11 includes the following steps:

[0026] S111, preparing a zinc precursor: mixing a zinc source, oleic acid and octadecene, stirring and heating to 120-130° C. under a protective atmosphere for vacuum treatment, then reintroducing the protective atmosphere and heating to 280-300° C. for 20-30 min, and then cooling to 250-260° C. to obtain a zinc precursor;

[0027] Preparing a selenium precursor: mixing selenium powder, octadecene and oleylamine, and subjecting the mixture to ultrasonic treatment to obtain a selenium precursor;

[0028] S112, preparing Mn:ZnSe core quantum dot stock solution: respectively mixing zinc source, octadecene and different amounts of manganese source, stirring under protective atmosphere and heating to 120-130°C for vacuum treatment, then reintroducing protective atmosphere and heating to 280-300°C, injecting selenium precursor, keeping the temperature at 300-320°C for 5-10 min, injecting zinc precursor solution, keeping the temperature at 300-320°C for 5-10 min, cooling to 75-85°C to obtain Mn:ZnSe core quantum dot stock solutions with different amounts of manganese ions doped;

[0029] S113, purifying Mn:ZnSe core quantum dots: mixing the core quantum dot stock solution obtained in step S12 with n-hexane, adding acetone or anhydrous ethanol to precipitate the quantum dots, collecting the precipitate by centrifugation, and washing it several times with a mixture of n-hexane and acetone to obtain purified Mn:ZnSe core solutions with different manganese ion doping amounts.

[0030] In step S111, the zinc source includes zinc oxide.

[0031] In step S112, the zinc source includes zinc stearate; and the manganese source includes manganese stearate.

[0032] As an embodiment of the present invention, step S12 includes the following steps:

[0033] S121, preparing a Zn(OA)2-OT mixed precursor solution: mixing a zinc source, oleic acid and octadecene, stirring under a protective atmosphere and heating to 100-120°C for vacuum treatment, then introducing a protective atmosphere and heating to 300-320°C and keeping the temperature for 10-20 min, cooling to 120-150°C, injecting a sulfur source and keeping the temperature at 120-150°C to obtain a Zn(OA)2-OT precursor solution;

[0034] S122. Preparation of Mn:ZnSe / ZnS core-shell structure quantum dots: dissolve the Mn:ZnSe core solution with different manganese ion doping amounts obtained in step S1 in octadecene, heat the temperature to 100-120°C under a protective atmosphere for vacuum treatment, then introduce a protective atmosphere, heat the temperature to 300-320°C for growth of the ZnS shell layer, and inject the Zn(OA)2-OT precursor solution of step S21 into the core, and keep the temperature at 300-320°C for 30-60 min to obtain Mn:ZnSe / ZnS core-shell structure quantum dot solutions with different manganese ion doping amounts.

[0035] In S221, the sulfur source includes at least one of n-octyl mercaptan, thioacetamide and sulfur powder; the zinc source includes at least one of zinc acetate, zinc stearate, zinc acetate and zinc sulfate; in the Zn(OA)2-OT precursor solution, the concentration of the zinc source is 0.01-0.03 mol / L, and the concentration of the sulfur source is 0.0005-0.001 mol / L;

[0036] And / or, the volume ratio of n-octadecene to oleic acid is 0.5-1.5:0.5-1.5.

[0037] As another embodiment of the present invention, step S2 includes the following steps:

[0038] S21, preparing a Zn(OA)2-OT mixed precursor solution: mixing zinc oxide, oleic acid and octadecene, stirring under a protective atmosphere and heating to 100-120°C for vacuum treatment, then introducing a protective atmosphere and heating to 300-320°C and keeping the temperature for 10-20 min, cooling to 120-150°C, injecting n-octyl mercaptan and keeping the temperature at 120-150°C to obtain a Zn(OA)2-OT precursor solution;

[0039] S22. Preparation of Mn:ZnSe / ZnS core-shell structure quantum dots: dissolve the Mn:ZnSe core solution with different manganese ion doping amounts obtained in step S1 in octadecene, heat the temperature to 100-120°C under a protective atmosphere for vacuum treatment, then introduce a protective atmosphere, heat the temperature to 300-320°C for growth of the ZnS shell layer, and inject the Zn(OA)2-OT precursor solution of step S21 into the core. After keeping the temperature at 300-320°C for 30-60 min, obtain Mn:ZnSe / ZnS core-shell structure quantum dot solutions with different manganese ion doping amounts.

[0040] The protective atmosphere mentioned above includes inert gases such as nitrogen and argon.

[0041] Step S2 includes the following steps:

[0042] S21, adjusting the concentration of quantum dot solutions with different lifespans under the same excitation light (405 nm) using a diluent (toluene) so that the number of photons emitted by them is consistent;

[0043] S22, respectively taking quantum dot solutions with the same number of photons but different lifetimes and placing them on a fluorescence lifetime imaging microscope for detection, collecting lifetime signals and converting them into clusters on a phase semicircle, which are defined as the primary lifetime codes of the quantum dot solutions;

[0044] S23, mixing two different primary lifetime coded quantum dot solutions in a specific volume ratio to obtain a secondary lifetime coded quantum dot mixed solution, making a quantum dot smear and placing it on a fluorescence lifetime imaging microscope for detection, collecting lifetime signals and converting them into clusters on a phase semicircle, each cluster representing different lifetime information;

[0045] S24, mixing the quantum dot solutions of primary lifetime coding and secondary lifetime coding in different volume ratios to obtain a quantum dot solution of tertiary lifetime coding, making a quantum dot smear and placing it on a fluorescence lifetime imaging microscope for detection, collecting the lifetime signal and converting it into clusters on a phase semicircle, each cluster representing different lifetime information;

[0046] S25. Select at least two quantum dot solutions with lifetime coding at different levels, mix them in various combinations and different volume ratios, and obtain a quantum dot solution with multi-level composite lifetime coding; make the solution into a quantum dot smear and place it on a fluorescence lifetime imaging microscope for detection, collect the lifetime signal and convert it into clusters on a phase semicomb, each cluster represents a unique combination of lifetime information, and realizes more complex and diversified lifetime coding.

[0047] As an embodiment of the present invention, step S2 includes the following steps:

[0048] S21, adjusting the concentration of quantum dot solutions with different lifespans using a diluent (toluene) under the excitation of an excitation light (405 nm) so that the number of photons emitted by the solutions is consistent;

[0049] S22, respectively taking quantum dot solutions with the same number of photons but different lifetimes and placing them on a fluorescence lifetime imaging microscope for detection, collecting lifetime signals and converting them into clusters on a phase semicircle, which are defined as the primary lifetime codes of the quantum dot solutions;

[0050] S23, mixing two different primary lifetime coded quantum dot solutions in a specific volume ratio to obtain a secondary lifetime coded quantum dot mixed solution, making a quantum dot smear and placing it on a fluorescence lifetime imaging microscope for detection, collecting lifetime signals and converting them into clusters on a phase semicircle, each cluster representing different lifetime information;

[0051] S24, mixing the quantum dot solutions of primary lifetime coding and secondary lifetime coding in different volume ratios to obtain a quantum dot solution of tertiary lifetime coding, making a quantum dot smear and placing it on a fluorescence lifetime imaging microscope for detection, collecting the lifetime signal and converting it into clusters on a phase semicircle, each cluster representing different lifetime information;

[0052] S25, mixing two different secondary lifetime coded quantum dot solutions in different volume ratios to obtain a quaternary lifetime coded quantum dot solution, making a quantum dot smear and placing it on a fluorescence lifetime imaging microscope for detection, collecting lifetime signals and converting them into clusters on a phase semicircle, each cluster representing different lifetime information;

[0053] S26, mixing the quantum dot solutions of the secondary lifetime coding and the tertiary lifetime coding in different volume ratios to obtain the quantum dot solution of the quintuple lifetime coding, making a quantum dot smear and placing it on a fluorescence lifetime imaging microscope for detection, collecting the lifetime signal and converting it into clusters on the phasor semicircle, each cluster representing different lifetime information;

[0054] S27. Mix two different three-level lifetime-coded quantum dot solutions in different volume ratios; or mix three different two-level lifetime-coded quantum dot solutions in different volume ratios to obtain a six-level lifetime-coded quantum dot solution, place it on a fluorescence lifetime imaging microscope for detection, collect lifetime signals and convert them into clusters on a phasor semicompass, each cluster representing different lifetime information.

[0055] Step S3 includes the following steps:

[0056] S31. Name the quantum dot solutions with different levels of lifetime coding in a four-digit number in the manner of "intensity / lifetime", where the first two digits represent the fluorescence intensity and the last two digits represent the fluorescence lifetime;

[0057] S32, selecting at least two quantum dot solutions as ink, and printing a specific pattern according to the printing schematic diagram;

[0058] S33, performing intensity imaging on the printed pattern to obtain intensity encryption information based on the fluorescence intensity difference of the quantum dot solution;

[0059] S34, performing lifetime imaging on the printed pattern and combining it with the phase analysis method to obtain lifetime clusters, and performing a "gating" operation on the lifetime clusters of a specific quantum dot solution to obtain lifetime encryption information based on the difference in fluorescence lifetime of the quantum dot solution.

[0060] Step S4 includes the following steps:

[0061] S41, selecting four different levels of lifetime-encoded quantum dot solutions as printing inks, and naming them A, B, C and D respectively;

[0062] Among them, quantum dot solutions A, B, and D have different lifetimes but the same number of photons; C is obtained by mixing A and B;

[0063] S42, printing a pattern according to the encrypted pattern design drawing by a high-precision nanomaterial deposition inkjet printing system;

[0064] S43. According to the vector law of the phasor diagram, when quantum dot solutions A and B with different lifetimes but the same number of photons are mixed in equal proportions, the position of the mixed solution C in the phasor diagram is located at the midpoint of the line connecting A and B; this indicates that the position of C can be determined by the known properties of solutions A and B and the rules of the phasor diagram;

[0065] S44. Introduce another quantum dot solution with different lifetime as the decryption "key", named K. Theoretically, when K and A with different lifetimes but the same number of photons are mixed in equal proportions to form a mixed solution F, the position of F in the phasor diagram is located at the midpoint of the line connecting A and K; when K and D with the same number of photons are mixed in equal proportions to form a mixed solution E, the position of E is located at the midpoint of the line connecting A and K; when B and K are mixed in equal proportions to obtain a mixed solution G, the position of G in the phasor diagram is located at the midpoint of the line connecting B and K.

[0066] S45, diluting or concentrating the four quantum dot solutions with different lifetimes, K, A, B and D, in step S44 so that the number of photons satisfies A=B=D=K;

[0067] S46, printing the K ink in step S44 on the encrypted pattern in step S42; based on the vector rule of the phasor diagram, the cluster position of the phasor diagram changes: A is converted to F, B is converted to G, D is converted to E, and C is converted to E; further encryption of the encrypted pattern is achieved;

[0068] S47. By decoding the position of cluster E, the real information "SJTU" is obtained.

[0069] The present invention prepares smears from quantum dot solutions with different lifetimes, and uses fluorescence lifetime imaging microscopy and phasor analysis to regulate the quantum dot lifetime levels based on vector laws to achieve precise design, prediction and analysis.

[0070] The phase analysis method is a data processing method for fluorescence lifetime signals.

[0071] The phasor analysis method can directly convert the lifetime information of each pixel point in the fluorescence intensity imaging diagram into a point in the phasor diagram.

[0072] The phasor diagram is a semicircle with G as the horizontal axis, ranging from 0-1, and S as the vertical axis, ranging from 0-0.5.

[0073] Each point in the semicircle represents a corresponding life span information, and the life span decreases from left to right. The (0,0) coordinate represents an infinite life span, and the (0,1) coordinate represents an infinitely small life span.

[0074] The life information on the semicircle compass follows the vector addition law. In a geometric sense, the phasor endpoints corresponding to the two life mixed materials should be located on the connecting line of the life phasor endpoints corresponding to their respective life materials, and the distance from the two end points is determined by the proportion of the two components.

[0075] Quantum dot solutions with different lifespans are used as printing inks, and encrypted patterns are printed through a high-precision nanomaterial inkjet deposition printing system, and clusters at different positions appear in the phase diagram.

[0076] A quantum dot ink is used as the "key K" and printed on top of the previous encryption pattern. The position of the clusters in the phasor diagram changes, and the real encrypted information can be obtained by decoding the position of the "key".

[0077] The "key" is a quantum dot ink with another lifetime. When it is printed on top of the previous pattern, the positions of clusters at three different locations change due to the combination of multiple fluorescence lifetimes and the addition rule in the phasor diagram, thereby achieving encryption and decoding.

[0078] According to another aspect of the present invention, a fluorescence lifetime analysis method based on the combination of fluorescence lifetime imaging microscopy and phase analysis as described above is also provided. The method can be used to accurately design, predict and analyze the lifetime signals of quantum dot solutions with different lifetime codes, and realize multi-level lifetime combination coding through hierarchical regulation.

[0079] According to another aspect of the present invention, a dynamic encryption strategy of "lifetime + strength" based on the phasor addition rule is provided for use in the field of anti-counterfeiting encryption.

[0080] The application of the lifetime signal combination encoding method based on quantum dot solution in the field of anti-counterfeiting encryption also falls within the protection scope of the present invention.

[0081] Compared with the prior art, the present invention has the following beneficial effects:

[0082] 1. The present invention provides a method for preparing quantum dot solutions encoded with different lifetimes. By changing the amount of transition metal elements added during the quantum dot preparation process, quantum dot solutions with different lifetimes can be obtained.

[0083] 2. The present invention utilizes fluorescence lifetime imaging microscopy and phasor analysis technology, combined with the vector addition law in the semi-compass, to mix quantum dot solutions of different lifetimes in proportion, and through hierarchical regulation, realizes the design, prediction and analysis of lifetime combination signals.

[0084] 3. This method is a visual fluorescence lifetime analysis method that does not require fitting, and is much faster than traditional fitting methods. It can also present pixels with similar attenuation characteristics in the form of "phasor clusters", has powerful data visualization capabilities, and is also convenient for clustering data analysis. Using this method, a dynamic encryption strategy based on fluorescence intensity and fluorescence lifetime can be realized, which has very important significance and broad application prospects in the field of encryption and anti-counterfeiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0086] Figure 1 TEM images of quantum dot nanoparticles obtained in Example 1 of the present invention and lifetime decay curves of six quantum dots with different lifetimes; (where a is an electron microscope image of quantum dots; b is lifetime decay curves of six different manganese-doped quantum dots);

[0087] Figure 2 is a primary lifetime coded phasor cluster diagram of six quantum dot solutions with different lifetimes obtained in Example 2 of the present invention;

[0088] Figure 3 It is a phasor cluster diagram of the quantum dot solution obtained in Example 3 of the present invention from the secondary lifetime coding to the sixth lifetime coding; wherein a is the secondary coding, which can be obtained from two primary codings; b is the third level coding, which can be obtained from the primary coding and the secondary coding; c is the fourth level coding and the fifth level coding, wherein the fourth level coding can be obtained from two secondary codings, and the fifth level coding can be obtained from the second and third level codings; d and e are both sixth level coding, wherein the d diagram is obtained from three secondary codings, and the e diagram is obtained from two third level codings; and f is an integrated diagram of all coding clusters from the first to the sixth level;

[0089] Figure 4 is the two-dimensional "strength + life" encryption strategy diagram obtained in Example 4 of the present invention; wherein:

[0090] a is a schematic diagram of the printing design using 0101 and 0102, two quantum dot inks with the same intensity but different lifespans;

[0091] b is the actual printing result using 0101 and 0102 quantum dot inks with the same intensity but different lifespans;

[0092] c is a schematic diagram of the printing design using four quantum dot inks: 0101, 0102, 0201 and 0202;

[0093] d is the actual printing result using four quantum dot inks: 0101, 0102, 0201 and 0202;

[0094] e is the phasor result diagram of phasor analysis of the results in Figure b;

[0095] f is the phasor result diagram of phasor analysis of the results in Figure d;

[0096] g is to identify the decoding clusters in figure e, and obtain the real information graph;

[0097] h is to identify the decoding clusters in figure f, and obtain the real information graph;

[0098] Figure 5 It is the strategy diagram of dynamic encryption anti-counterfeiting obtained in Example 5 of the present invention; wherein:

[0099] a is a schematic diagram of dynamic encryption anti-counterfeiting, which includes four inks A, B, C and D used in printing;

[0100] b is a schematic diagram of an encrypted pattern designed using four quantum dot inks A, B, C and D. A, B, C and D are used to print out Figure b according to the design;

[0101] c is the key ink K superimposed in situ on Figure b to obtain the real information map;

[0102] d is the phasor analysis of the actual printing pattern designed according to Figure b;

[0103] e is to give different pseudo colors to the four clusters A, B, C, and D in Figure d, and obtain the corresponding phasor pseudo color superposition encryption image;

[0104] f is a pseudo-color image of the individual phase quantities of the clusters corresponding to the four quantum dot inks A, B, C, and D in Figure d;

[0105] Figure g is the phasor diagram of key ink K;

[0106] Figure h is a phasor diagram obtained by in-situ superimposing and printing the key ink K on the encrypted pattern in Figure e;

[0107] Figure i is the phasor pseudo-color pattern of the clusters corresponding to the four quantum dot inks E, F, and G in Figure h, where E is the real information. DETAILED DESCRIPTION

[0108] The following further describes the structures involved in the present invention or the technical terms used. These descriptions are only used as examples to illustrate how the methods of the present invention are implemented, and cannot constitute any limitation to the present invention. The scope of the present invention is defined and expressed by the claims.

[0109] Organic solvents

[0110] Organic solvents are a large class of organic compounds that are widely used in life and production. They have a small molecular weight and are found in coatings, adhesives, paints and detergents. Commonly used organic solvents include styrene, perchloroethylene, trichloroethylene, ethylene glycol ether and triethanolamine. Organic solvents can dissolve some organic compounds that are insoluble in water (such as grease, wax, resin, rubber, dye, etc.). They are characterized by being liquid at room temperature and pressure and having high volatility. During the dissolution process, the properties of the solute and the solvent do not change. Solvents cannot react chemically with solutes and are inert.

[0111] Inert organic solvents mainly include benzene, toluene, xylene, o-xylene, m-xylene, p-xylene, hexamethylbenzene, ethylbenzene, n-propylbenzene, isopropylbenzene, biphenyl, diphenylmethane, triphenylmethane, styrene, phenylacetylene, naphthalene, tetralin, anthracene, phenanthrene, pyrene, chloroform, N-methylpyrrolidone, diphenyl ether, acetone, methyl butyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, diacetone alcohol, silicone, tetraethylene glycol dimethyl Ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, nitrobenzene, carbon tetrachloride, ethylene dichloride, chlorobenzene, dichlorobenzene, dichloromethane, chloropicrin, methyl bromide, dichloropropane, dibromoethylene, chloroform, dimethyl sulfoxide, acetone, acetonitrile, dimethylformamide, carbon tetrachloride, cyclohexane, cyclohexanone, toluene cyclohexanone, pyridine, phenol, carbon tetrachloride, isooctane, ethyl ether, pentane, hexane, propylene oxide, etc.

[0112] In some embodiments, the organic solvent used to form a dispersed phase between the polymer and the organic solvent in the present invention is one of toluene, ethylbenzene, chloroform, dichloromethane, acetone, acetonitrile, and diethyl ether.

[0113] quantum dots

[0114] Quantum dots are semiconductor nanostructures that bind excitons in three spatial directions. Sometimes called "artificial atoms", "superlattices", "superatoms" or "quantum dot atoms", they are a new concept proposed in the 1990s. Quantum dots are semiconductor nanocrystals with a radius smaller than or close to the Bohr exciton radius. Due to their unique fluorescent nano effect, their excitation spectrum is wide and continuously distributed, and their emission spectrum is narrow and symmetrical. The emission wavelength can be regulated by changing the particle size and composition. They have strong fluorescence intensity, slow bleaching rate and high sensitivity. They are widely used in photocatalysis, photosensors, luminescent materials, fluorescent probe labels and other fields. In particular, quantum dots composed of group IIB and group VIA elements (such as CdSe) have important value in biomedical fluorescent probe markers and sensors due to their excellent fluorescence emission properties in the visible and near-infrared spectral regions. Quantum dots have separate quantized energy spectra. The corresponding wave function is located in the quantum dot in space, but extends over several lattice periods. A quantum dot has a small number (1-100) of integer electrons, holes or electron-hole pairs, that is, the charge it carries is an integer multiple of the elementary charge. Quantum dots mainly include CdSe / ZnS, CdSe / CdS, CdTeSe / ZnS, CdTe / CdSe / ZnS, CdTe, Ag2S, Ag2Se, InAs, InP, HgTe, PbS, PbSe, CuInS2, CuInSe2, CdSeTe, CdHgTe, InP / ZnS, InAs / CdSe, C dTe / CdS, CdTe / ZnS, CdTe / CdSe, ZnTe / CdTe, ZnTe / CdSe, ZnTe / CdS, CdSeTe / CdS, Cu :CdS / ZnS, Mn:ZnSe / ZnS, CuInS2 / ZnS, CuInSe2 / ZnS, CsPbCl3, CsPbBr3, CsPbI3, Cs Pb(Cl / Br)3, CsPb(Br / I)3, CH3NH3PbI3, CH3NH3PbBr3, CdSe, CdS, ZnSe, ZnTe, ZnO, HgSe, HgS, CaAs, InCaAs, CdSe / ZnSe, CdS / ZnS, CdS / Ag2S, CdS / Cd(OH)2, CdSe / ZnSe , CdS / HgS, CdS / HgS / CdS, ZnS / CdS, ZnS / CdS / ZnS, ZnS / HgS / ZnS / CdS, CdSe / CuSe, Cd SeTe / CdS / ZnS, CdSe / CdS / ZnS, CdS:Mn, ZnS:Mn, CdS:Cu, ZnS:Cu, CdS:Tb, ZnS:Tb, etc.

[0115] In some embodiments, the quantum dots with different lifetimes in the present invention mainly include (CdSe / ZnS, CdSe / CdS, CdTeSe / ZnS, CdTe / CdSe / ZnS, CdTe, Ag2S, Ag2Se, InAs, InP, HgTe, PbS, PbSe, CuInS2, CuInSe2, CdSeTe, CdHgTe, InP / ZnS, InAs / CdSe, CdTe / CdS, CdTe / ZnS , CdTe / CdSe, ZnTe / CdTe, ZnTe / CdSe, ZnTe / CdS, CdSeTe / CdS, Cu:CdS / ZnS, Mn:ZnSe / ZnS, CuInS2 / ZnS, CuInSe2 / ZnS, CsPbCl3, CsPbBr3, CsPbI3, CsPb(Cl / Br)3, CsPb(Br / I)3, CH3NH3PbI3, CH3NH3PbBr3), etc.

[0116] Example 1 Preparation of core-shell quantum dot solutions doped with transition metal elements of different lifetimes

[0117] The quantum dots prepared in this embodiment are Mn:ZnSe / ZnS, and the specific preparation steps are as follows:

[0118] (1) 406.9 mg of zinc oxide, 7.05 mL of oleic acid and 12.95 mL of octadecene were placed in a three-necked glass flask, heated to 120°C under nitrogen protection and magnetic stirring, and evacuated for 1 hour. After nitrogen was introduced again, the temperature was raised to 280°C, kept at this temperature for 20 minutes, and then lowered to 250°C to obtain a zinc oleate precursor.

[0119] (2) 156 mg of selenium powder, 5.6 mL of octadecene and 2.4 mL of oleylamine were placed in a centrifuge tube and mixed by ultrasonication for 5 min to obtain a selenium precursor.

[0120] (3) Take 243 mg of zinc stearate, 20 mL of octadecene, and (5 mg, 10 mg, 20 mg, 40 mg, 80 mg, 160 mg) of manganese stearate respectively and place them in a three-necked glass flask. Heat to 120 °C under nitrogen protection and magnetic stirring, and evacuate for 1 hour. Pass nitrogen and heat to 300 °C, and quickly inject selenium precursor. Keep warm at 300 °C for 5 minutes, inject 1.6 mL of zinc oleate precursor solution dropwise, cool to 200 °C, inject 1.6 mL of zinc oleate precursor dropwise, heat to 260 °C and keep warm for 10 minutes, inject 1.6 mL of zinc oleate precursor dropwise again, inject 1.6 mL of zinc oleate precursor for the third time after 10 minutes, keep warm for 5 minutes and then cool down to obtain Mn:ZnSe core quantum dot stock solution with different manganese ion doping amounts.

[0121] (4) 25 mL of n-hexane was added to the Mn:ZnSe core quantum dot stock solution with different manganese ion doping amounts in step (3), and a large amount of acetone was added after mixing to precipitate the quantum dots in the stock solution, and centrifuged at 10,000 rpm for 5 min. Subsequently, the mixture was centrifuged and washed three times with a mixture of n-hexane and acetone in a volume ratio of 2:7, at a centrifugal speed of 10,000 rpm and a centrifugal time of 5 min / time, and the precipitate was collected. The purified Mn:ZnSe core quantum dots with different manganese ion doping amounts were dispersed in toluene and stored at 4°C for use.

[0122] (5) 781 mg of zinc oxide, 9 mL of oleic acid and 22.5 mL of octadecene were placed in a three-necked glass flask, heated to 100°C under nitrogen protection and magnetic stirring, and vacuum was started while continuing to heat to 120°C. After vacuum for 30 minutes, nitrogen was introduced, and the temperature was raised to 315°C and kept warm for 15 minutes. Finally, the reaction solution was cooled to 150°C, 3.2 mL of n-octyl mercaptan (OT) was injected, and kept warm at 150°C for use, to obtain a mixed precursor solution of zinc oleate and OT (Zn(OA)2-OT precursor solution).

[0123] (6) The toluene solutions of Mn:ZnSe core quantum dots with different manganese ion doping amounts in (4) were centrifuged at low speed, and the supernatant was dissolved in 10 mL of octadecene. The temperature was raised to 100°C under nitrogen protection and magnetic stirring, and the solution was evacuated for 30 minutes. Nitrogen was introduced and the temperature was raised to 310°C to grow the ZnS shell layer. 9 mL of the Zn(OA)2-OT precursor solution in step (5) was injected with an injection pump at an injection rate of 6 mL / h, and the solution was kept at 310°C for 30 minutes to obtain Mn:ZnSe / ZnS core-shell structure quantum dots with different manganese ion doping amounts. When the temperature was lowered to 80°C, the solution was centrifuged and washed with n-hexane and acetone (the volume ratio of the two was 2:7). The centrifugal washing method was the same as step (4). Finally, the purified quantum dots were dissolved in toluene and stored at 4°C. The TEM image is shown as follows. Figure 1 As shown (where a is a high-resolution electron microscope image of quantum dots; b is the lifetime decay curves of six different manganese-doped quantum dots).

[0124] (7) Pass Figure 1 It can be found that by changing the doping amount of manganese stearate, six quantum dot solutions with different lifetime decay curves can be obtained.

[0125] Example 2: First-level life coding

[0126] (1) The six quantum dot solutions with different lifetimes in Example 1 were diluted with toluene respectively, and the number of photons emitted was made consistent by adjusting the concentration (so that the final concentration was 10 mg / mL) under the excitation of 405 nm excitation light.

[0127] (2) 10 μL of each of the six quantum dot solutions with the same photon number but different lifetimes was coated on a cover glass to make a quantum dot smear, which was then placed on a fluorescence lifetime imaging microscope for detection. The objective lens was a 60x water lens, the excitation light was 405 nm, the excitation frequency was 1000 Hz, the detector was an APD detector, and the fluorescence channel was 615 / 40 nm.

[0128] (3) Select the region where the quantum dots emit light uniformly for fluorescence imaging, and use the FastFLIM FLIMbox of ISS to collect the lifetime signal. After imaging, the fluorescence imaging image is directly converted into six clusters on the phasor semicircle (such as Figure 2 ), which is defined as the primary lifetime encoding of the quantum dot solution, namely Figure 2 Medium QDt 11 -QD 16 Six quantum dot lifetime-encoded clusters.

[0129] Embodiment 3 Multi-level life coding

[0130] (1) According to the vector law of the phasor semi-compass, when the photon numbers of two primary lifetime coded quantum dot solutions are the same, their cluster positions on the semi-compass are known. 11 -QD 16 If any two quantum dots in the solution are mixed in different volume ratios, the cluster position of the mixed sample on the semi-compass is located on the cluster line before the two solutions are mixed, and the distance from both sides is equal, which is defined as the secondary lifetime encoding. Similarly, according to this principle, the hierarchical design and regulation of the lifetime of quantum dot solutions can be achieved.

[0131] (2) For the secondary life coding, QDt is divided into the following volume ratios: 5:1, 4:2, 3:3, 2:4 and 1:5. 11 and QDt 16 The two quantum dot solutions were mixed to obtain five quantum dot mixed solutions, which were named QDt 21 , QDt 22 , QDt 23 , QDt 24 and QDt 25 ;

[0132] QDt was added in a 1:1 volume ratio 13 and QDt 14 Two quantum dot solutions were mixed and named QDt 26 ;

[0133] QDt was added in a 1:1 volume ratio 12 and QDt 13Two quantum dot solutions were mixed and named QDt 27 ,

[0134] The entire quantum dot solution was made into a quantum dot smear, which was placed on a fluorescence lifetime imaging microscope for detection. The objective lens was a 60x water lens, the excitation light was 405nm, the excitation frequency was 1000Hz, the detector was an APD detector, and the fluorescence channel was 615 / 40nm. The fluorescence imaging picture was directly converted into clusters on the phase semicircle by SimFCS-64 software, such as Figure 3 As shown in the secondary encoding in a, each cluster represents different lifetime information.

[0135] (3) For the three-level life code, the first-level code obtained in Example 2 and the second-level code obtained in step (2) of Example 3 are mixed in different volume ratios.

[0136] like Figure 3 The three-level coding in b is as follows:

[0137] Mix the quantum dot solution QDt in a volume ratio of 1:1 13 and QDt 21 , and obtain the three-level lifetime code QDt 31 ;

[0138] Mix the quantum dot solution QDt in a volume ratio of 1:1 14 and QDt 25 , and obtain the three-level lifetime code QDt 32 ;

[0139] All quantum dot solutions were made into quantum dot smears and placed on a fluorescence lifetime imaging microscope for detection. The objective lens was a 60x water lens, the excitation light was 405nm, the excitation frequency was 1000Hz, the detector was an APD detector, and the fluorescence channel was 615 / 40nm. The fluorescence imaging pictures were directly converted into clusters on the phase semicircle by SimFCS-64 software, representing different lifetime information.

[0140] (4) For the fourth-level lifetime code, any two secondary codes obtained in step (2) of Example 3 are mixed in different volume ratios to obtain a fourth-level lifetime code.

[0141] like Figure 3 As shown in c, the quantum dot solution QDt is mixed in a volume ratio of 2:1 26 and QDt 23 , making quantum dot smears, and obtaining four-level lifetime coding QDt 41; Place it on a fluorescence lifetime imaging microscope for detection. The objective lens is a 60x water lens, the excitation light is 405nm, the excitation frequency is 1000Hz, the detector is an APD detector, and the fluorescence channel is 615 / 40nm. The fluorescence imaging picture is directly converted into clusters on the phase semicircle by SimFCS-64 software, representing different lifetime information.

[0142] (5) For the five-level life code, the second-level code obtained in step (2) of Example 3 and the third-level code obtained in step (3) can be mixed in different volume ratios to obtain the five-level life code.

[0143] like Figure 3 As shown in c, the quantum dot solution QDt is mixed in a volume ratio of 1:1 26 and QDt 31 , and obtain the five-level lifetime code QDt 51 , make a quantum dot smear, and place it on a fluorescence lifetime imaging microscope for detection. The objective lens is a 60x water lens, the excitation light is 405nm, the excitation frequency is 1000Hz, the detector is an APD detector, and the fluorescence channel is 615 / 40nm. The fluorescence imaging picture is directly converted into clusters on the phase semicircle by SimFCS-64 software, representing different lifetime information.

[0144] (6) For six-level life coding.

[0145] The three different secondary codes obtained in step (2) of Example 3 are mixed in different volume ratios to obtain a six-level life code; Figure 3 As shown in d, the quantum dot solution QDt can be mixed in a volume ratio of 1:1:1 22 , QDt 24 and QDt 26 Mixed to obtain six-level lifetime coding QDt 61 ;

[0146] The two three-level codes obtained in step (3) are mixed in different volume ratios to obtain a six-level lifetime coding quantum dot solution. Figure 3 As shown in e, the quantum dot solution QDt was mixed according to the volume ratio of 2:1 and 1:2. 31 and QDt 32 Mixed to obtain six-level lifetime coding QDt 62 and QDt 63, the quantum dot solution was made into a quantum dot smear, which was placed on a fluorescence lifetime imaging microscope for detection. The objective lens was a 60x water lens, the excitation light was 405nm, the excitation frequency was 1000Hz, the detector was an APD detector, and the fluorescence channel was 615 / 40nm. The fluorescence imaging image was directly converted into clusters on the phase semicircle by SimFCS-64 software, representing different lifetime information. All quantum dot lifetime coding clusters from primary coding to sixth level coding are shown in Figure 3 f.

[0147] Example 4

[0148] Two quantum dot solutions were selected, namely, primary coding QDt 14 Quantum dot solution and secondary coding QDt 26 Quantum dot solutions are named according to the "intensity / lifetime" four-digit "0000", QDt 14 is "0101", QDt 26 "0102", representing QDt 14 and QDt 26 The fluorescence intensity is consistent, both are "01"; the fluorescence lifetime is different, QDt 14 The life span is "01", QDt 26 The life span is "02".

[0149] (1) QDt 14 "0101" and QDt 26 "0102" is used as ink, and the pattern "8888" is printed according to the printing schematic diagram.

[0150] (2) Perform intensity imaging on “8888” to obtain the intensity encryption information of “8888”.

[0151] (3) Lifetime imaging of "8888" was performed, and two lifetime clusters were obtained by further combining the phase analysis method. 26 "Circle door" to obtain the encrypted life span information of "2024".

[0152] (4) Select four quantum dot solutions (two different concentrations of QDt 14 and two different concentrations of QDt 26 ) as ink,

[0153] According to the "strength life", the four-digit number "0000" is named.

[0154] Solution 1 (QDt 14 ) is "0101", solution 2 (QDt 26 ) is "0102", solution three (QDt 14 ) is "0201", solution four (QDt26 ) is "0202", solution 1 (QDt 14 ) and solution 2 (QDt 26 ) have the same fluorescence intensity, all of which are "01", and solution three (QDt 14 ) and solution four (QDt 26 ) have the same fluorescence intensity, all of which are "02", solution 1 (QDt 14 ) and solution three (QDt 14 ) have the same fluorescence lifetime, both are "01", solution 2 (QDt 26 ) and solution four (QDt 26 ) have the same fluorescence lifetime, which is “02”.

[0155] (5) Solution 1 "0101", solution 2 "0102", solution 3 "0201" and solution 4 "0202" are used as inks to print the pattern "8888" according to the printing schematic diagram.

[0156] (6) Perform intensity imaging on “8888” to obtain the intensity encryption information of “1111”.

[0157] (7) Lifetime imaging of "8888" was performed, and two lifetime clusters were obtained by further combining the phase analysis method. 26 "Circle Gate" and get the encrypted life span information of "1896".

[0158] Figure 4 is the two-dimensional "strength + lifespan" encryption strategy obtained in this embodiment; Figure 4 is the two-dimensional "strength + life" encryption strategy diagram obtained in Example 4 of the present invention; wherein:

[0159] a is a schematic diagram of the printing design using 0101 and 0102, two quantum dot inks with the same intensity but different lifespans;

[0160] b is the actual printing result using 0101 and 0102 quantum dot inks with the same intensity but different lifespans;

[0161] c is a schematic diagram of the design for printing using four quantum dot inks: 0101, 0102, 0201 and 0202;

[0162] d is the actual printing result using four quantum dot inks: 0101, 0102, 0201 and 0202;

[0163] e is the phasor result diagram of phasor analysis of the results in Figure b;

[0164] f is the phasor result diagram of phasor analysis of the results in Figure d;

[0165] g is to identify the decoding clusters in figure e, and obtain the real information graph;

[0166] h is used to identify the decoding clusters in figure f, and the real information graph can be obtained.

[0167] Example 5

[0168] Four quantum dot solutions with different lifetimes (QDt 14 ,QD 63 ,QD 13 and QDt 41 ) are used as printing inks, named A, B, C and D respectively. The photon numbers of A, B and D are controlled to be consistent. C is obtained by mixing A and B with the same photon number and volume. The pattern is printed according to the encrypted pattern design through a high-precision nanomaterial deposition inkjet printing system.

[0169] (1) According to the vector law of the phasor diagram, when quantum dot solutions A and B with different lifetimes but the same number of photons are mixed in equal proportions, the position of the mixed solution C in the phasor diagram is located at the midpoint of the line connecting A and B. Similarly, when quantum dot solutions "Key K" and A with different lifetimes but the same number of photons are mixed in equal proportions, the position of the mixed solution F in the phasor diagram is located at the midpoint of the line connecting A and "Key K". Similarly, the position of E can be known from "Key K" and D, and the position of G can be known from "Key K" and B.

[0170] (2) Using a quantum dot solution with different lifetimes from A, B, C, and D as the "key K", by adjusting the photon number of the three quantum dot printing inks with different lifetimes and the "key K" ink in step (1), the photon number satisfies A=B=D=K.

[0171] (3) The "key K" ink in step (2) is printed on top of the encrypted pattern in step (1). Due to the vector rule of the phasor diagram described in step (2), the following changes are achieved in the cluster positions of the phasor diagram: A is converted to F, B is converted to G, D is converted to E, and C is also converted to E.

[0172] (4) By decoding the position of cluster E, the real information “SJTU” is obtained.

[0173] Figure 5It is a strategy diagram of dynamic encryption and anti-counterfeiting obtained in Example 5 of the present invention; wherein a is a schematic diagram of dynamic encryption and anti-counterfeiting, including four inks A, B, C and D used for printing; b is a schematic diagram of an encrypted pattern designed using four quantum dot inks A, B, C and D, and A, B, C, D are used to print out the b diagram according to the design, and then the key ink K is superimposed in situ to obtain the real information c diagram, c is the actual printed pattern designed according to the left diagram of the b diagram, and d is subjected to phasor analysis, and different pseudo colors are given to the four clusters A, B, C, and D, and the corresponding phasor pseudo-color superposition diagram e is obtained. f is a separate phasor pseudo-color diagram for the clusters corresponding to the four quantum dot inks A, B, C, and D in Figure d, g is a phasor diagram of the key ink K, h is a phasor diagram obtained by superimposing the key ink K in situ on the basis of the encrypted pattern in Figure e, and i is a phasor pseudo-color pattern for the clusters corresponding to the four quantum dot inks E, F, and G in Figure h, where E is the real information.

[0174] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A lifetime signal combination encoding method based on quantum dot solution, characterized in that: The encoding method comprises the following steps: S1. preparing core-shell quantum dot solutions doped with transition metal elements of different lifetimes according to different doping amounts; S2. Quantum dot solutions with different lifetimes are combined in different proportions to obtain quantum dot solutions with different levels of lifetime coding; quantum dot solutions with different levels of lifetime coding are regulated by fluorescence lifetime imaging microscopy and phase analysis based on the vector law to achieve precise design, prediction and analysis; S3, using quantum dot solutions with different levels of lifetime coding as printing ink to print encrypted patterns, and clusters at different positions appear in the phasor diagram; S4, use another quantum dot ink as a key, superimpose it on the encryption pattern of S3, the cluster position in the phasor diagram changes, and the real encrypted information is obtained by decoding the position of the key.

2. The lifetime signal combination encoding method according to claim 1, characterized in that: Step S1 includes the following steps: S11, adding a zinc source and a manganese source in different proportions to a solvent to form a mixed solution, degassing, adding a selenium precursor solution after heating, and then adding a zinc precursor solution to obtain a Mn:ZnSe core solution with different manganese ion doping amounts; S12. Degas the Mn:ZnSe core solutions with different manganese ion doping amounts obtained in step S11, add Zn(OA)2-OT mixed precursor solutions after heating, and keep warm for a period of time to obtain Mn:ZnSe / ZnS core-shell structure quantum dot solutions with different manganese ion doping amounts; that is, core-shell quantum dot solutions doped with transition metal elements with different lifespans.

3. The lifetime signal combination encoding method according to claim 2, characterized in that: Step S11 includes the following steps: S111, preparing a zinc precursor: mixing a zinc source, oleic acid and octadecene, stirring and heating to 120-130° C. under a protective atmosphere for vacuum treatment, then reintroducing the protective atmosphere and heating to 280-300° C. for 20-30 min, and then cooling to 250-260° C. to obtain a zinc precursor; Preparing a selenium precursor: mixing selenium powder, octadecene and oleylamine, and subjecting the mixture to ultrasonic treatment to obtain a selenium precursor; S112, preparing Mn:ZnSe core quantum dot stock solution: respectively mixing zinc source, octadecene and different amounts of manganese source, stirring under protective atmosphere and heating to 120-130°C for vacuum treatment, then reintroducing protective atmosphere and heating to 280-300°C, injecting selenium precursor, keeping the temperature at 300-320°C for 5-10 min, injecting zinc precursor solution, keeping the temperature at 300-320°C for 5-10 min, cooling to 75-85°C to obtain Mn:ZnSe core quantum dot stock solutions with different amounts of manganese ions doped; S113, purifying Mn:ZnSe core quantum dots: mixing the core quantum dot stock solution obtained in step S12 with n-hexane, adding acetone or anhydrous ethanol to precipitate the quantum dots, collecting the precipitate by centrifugation, and washing it several times with a mixture of n-hexane and acetone to obtain purified Mn:ZnSe core solutions with different manganese ion doping amounts.

4. The lifetime signal combination encoding method according to claim 2, characterized in that: Step S12 specifically includes the following steps: S121, preparing a Zn(OA)2-OT mixed precursor solution: mixing a zinc source, oleic acid and octadecene, stirring under a protective atmosphere and heating to 100-120°C for vacuum treatment, then introducing a protective atmosphere and heating to 300-320°C and keeping the temperature for 10-20 min, cooling to 120-150°C, injecting a sulfur source and keeping the temperature at 120-150°C to obtain a Zn(OA)2-OT precursor solution; S122. Preparation of Mn:ZnSe / ZnS core-shell structure quantum dots: dissolve the Mn:ZnSe core solution with different manganese ion doping amounts obtained in step S1 in octadecene, heat the solution to 100-120°C under a protective atmosphere for vacuum treatment, then introduce a protective atmosphere, heat the solution to 300-320°C for growth of the ZnS shell layer, and inject the Zn(OA)2-OT precursor solution of step S21 into the core. After keeping the temperature at 300-320°C for 30-60 min, obtain Mn:ZnSe / ZnS core-shell structure quantum dot solutions with different manganese ion doping amounts.

5. The lifetime signal combination encoding method according to claim 4, characterized in that: In S221, the sulfur source includes at least one of n-octyl mercaptan, thioacetamide and sulfur powder; And / or, the zinc source includes at least one of zinc acetate, zinc stearate, zinc acetate and zinc sulfate.

6. The lifetime signal combination encoding method according to claim 1, characterized in that: Step S2 includes the following steps: S21, adjusting the concentration of quantum dot solutions with different lifespans by using a diluent under the same excitation light so that the number of photons emitted by the solutions is consistent; S22, respectively taking quantum dot solutions with the same number of photons but different lifetimes and placing them on a fluorescence lifetime imaging microscope for detection, collecting lifetime signals and converting them into clusters on a phase semicircle, which are defined as the primary lifetime codes of the quantum dot solutions; S23, mixing two different primary lifetime coded quantum dot solutions in a specific volume ratio to obtain a secondary lifetime coded quantum dot mixed solution, making a quantum dot smear and placing it on a fluorescence lifetime imaging microscope for detection, collecting lifetime signals and converting them into clusters on a phase semicircle, each cluster representing different lifetime information; S24, mixing the quantum dot solutions of primary lifetime coding and secondary lifetime coding in different volume ratios to obtain a quantum dot solution of tertiary lifetime coding, making a quantum dot smear and placing it on a fluorescence lifetime imaging microscope for detection, collecting the lifetime signal and converting it into clusters on a phase semicircle, each cluster representing different lifetime information; S25. Select at least two quantum dot solutions with lifetime coding at different levels, mix them in various combinations and different volume ratios, and obtain a quantum dot solution with multi-level composite lifetime coding; make the solution into a quantum dot smear and place it on a fluorescence lifetime imaging microscope for detection, collect the lifetime signal and convert it into clusters on a phase semicomb, each cluster represents a unique combination of lifetime information, and realizes more complex and diversified lifetime coding.

7. The lifetime signal combination encoding method according to claim 6, characterized in that: In step S21, the wavelength of the excitation light is 405 nm.

8. The lifetime signal combination encoding method according to claim 1, characterized in that: Step S3 includes the following steps: S31, naming quantum dot solutions with different levels of lifetime coding in a four-digit manner according to the "intensity / lifetime" method, wherein the first two digits represent the fluorescence intensity and the last two digits represent the fluorescence lifetime; S32, selecting at least two quantum dot solutions as ink, and printing a specific pattern according to the printing schematic diagram; S33, performing intensity imaging on the printed pattern to obtain intensity encryption information based on the fluorescence intensity difference of the quantum dot solution; S34, lifetime imaging is performed on the printed pattern, and lifetime clusters are obtained by combining the phase analysis method. By performing a "gating" operation on the lifetime clusters of a specific quantum dot solution, lifetime encryption information based on the difference in fluorescence lifetime of the quantum dot solution is obtained.

9. The lifetime signal combination encoding method according to claim 1, characterized in that: Step S4 includes the following steps: S41, selecting four different levels of lifetime-encoded quantum dot solutions as printing inks, and naming them A, B, C and D respectively; Among them, quantum dot solutions A, B, and D have different lifetimes but the same number of photons; C is obtained by mixing A and B; S42, printing a pattern according to the encrypted pattern design drawing by a high-precision nanomaterial deposition inkjet printing system; S43. According to the vector law of the phasor diagram, when quantum dot solutions A and B with different lifetimes but the same number of photons are mixed in equal proportions, the position of the mixed solution C in the phasor diagram is located at the midpoint of the line connecting A and B; this indicates that the position of C can be determined by the known properties of solutions A and B and the rules of the phasor diagram; S44. Introduce another quantum dot solution with different lifetime as the decryption "key", named K; theoretically, when K and A with different lifetimes but the same number of photons are mixed in equal proportions to form a mixed solution F, the position of F in the phasor diagram is located at the midpoint of the line connecting A and K; K and D with the same number of photons are mixed in equal proportions to form a mixed solution E, and the position of E is located at the midpoint of the line connecting A and K; B and K are mixed in equal proportions to obtain a mixed solution G, and the position of G in the phasor diagram is located at the midpoint of the line connecting B and K; S45, diluting or concentrating the four quantum dot solutions with different lifetimes, K, A, B and D, so that the number of photons satisfies A=B=D=K; S46, printing the K ink in step S44 on the encrypted pattern in step S42; based on the vector rule of the phasor diagram, the cluster position of the phasor diagram changes: A is converted to F, B is converted to G, D is converted to E, and C is converted to E; further encryption of the encrypted pattern is achieved; S47. By decoding the position of cluster E, the real information "SJTU" is obtained.

10. An application of the lifetime signal combination encoding method based on quantum dot solution as described in any one of claims 1 to 9 in the field of anti-counterfeiting encryption.

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