CaZnOS semiconductor stress luminescent two-dimensional material and peeling method and application thereof

Abstract

The application provides a CaZnOS semiconductor stress luminescence two-dimensional material and a stripping method and application thereof. The stripping method of the semiconductor stress luminescence two-dimensional material of the application is characterized in that: a CaZnOS bulk material stacked by layers is placed in a sodium citrate buffer solution for treatment, the interlayer force is weakened through ion chelation and etching effect, and then ultrasonic stripping treatment is carried out, so that the strong bonding CaZnOS bulk material is successfully stripped into CaZnOS two-dimensional nanosheets with stress luminescence performance; wherein the CaZnOS Mn-doped two-dimensional nanosheet has a nanosecond-level fluorescence lifetime, which is reduced by six orders of magnitude compared with the fluorescence lifetime of the bulk material, from millisecond level to nanosecond level, and is suitable for high-resolution three-photon fluorescence imaging in biomedicine, and has the characteristics of strong signal, fast imaging speed, high biological safety and the like.

Description

Technical Field

[0001] This invention relates to the field of inorganic luminescent materials, and more particularly to a CaZnOS semiconductor stress-luminescent two-dimensional material, its exfoliation method, and its applications. Background Technology

[0002] Two-dimensional nanomaterials, due to their unique physicochemical properties, have shown great application potential in fields such as biomedicine, optoelectronics, and energy catalysis. Since the discovery of graphene, the scientific community has continuously focused on the development and exfoliation of layered materials. Among them, layered materials bound by van der Waals forces (such as MoS2) have formed relatively mature preparation systems due to their relatively easy exfoliation. However, for a large number of non-van der Waals materials bound by strong chemical bonds (such as ionic and covalent bonds), the extremely high interlayer interaction energy makes efficient and controllable exfoliation to prepare high-quality two-dimensional nanostructures a formidable challenge, which greatly limits the exploration and application of such materials at the nanoscale. In recent years, researchers have reported a novel two-dimensional material, "hematite-ene," obtained from natural hematite ore via liquid-phase exfoliation. For the first time, flame spray pyrolysis has been introduced as a general-purpose, scalable preparation technique. By annealing multi-component metal oxide nanoparticles into two-dimensional crystals through calcination or laser irradiation, ultra-high brightness metastable copper silicate nanosheets have been successfully synthesized.

[0003] In recent years, CaZnOS, as a direct bandgap semiconductor material, has attracted widespread research interest due to its excellent doping compatibility and multiple stimulus-response characteristics, including mechanoluminescence, photoluminescence, and long-afterglow luminescence. CaZnOS typically crystallizes in a hexagonal wurtzite structure (space group: P63mc), in which Zn... 2+ With Ca 2+ Ions occupy cation sites randomly or in an ordered manner, and interact with S 2- O 2- Anions form tetrahedral coordination. Their chemical bonds are essentially ionic-covalent hybrids: ionic bonds dominate between Ca and O / S, while covalent bonds dominate between Zn and O / S. Existing technologies disclose the preparation of bulk CaZnOS powder with a layered stacking growth pattern. While this method can effectively synthesize highly crystalline bulk CaZnOS materials with a layered stacking tendency, it does not solve the problem of ultimately exfoliating them into two-dimensional nanosheets. Because non-van der Waals materials such as CaZnOS possess strong interlayer chemical bonds, it is difficult to prepare structurally complete two-dimensional nanosheets using conventional mechanical or liquid-phase exfoliation methods. This severely limits the research and application of these materials' stress luminescence and piezoelectric properties at the nanoscale. Summary of the Invention

[0004] To address the aforementioned technical deficiencies, this invention provides a CaZnOS semiconductor stress-luminescent two-dimensional material, its exfoliation method, and its applications. The exfoliation method for this semiconductor stress-luminescent two-dimensional material involves treating bulk CaZnOS material in a sodium citrate buffer solution. Interlayer forces are weakened through ion chelation and etching, followed by ultrasonic exfoliation. This successfully exfoliates the strongly bonded CaZnOS bulk material into CaZnOS two-dimensional nanosheets, which possess stress-luminescent properties. The Mn-doped CaZnOS two-dimensional nanosheets exhibit nanosecond-level fluorescence lifetimes, which are six orders of magnitude shorter than those of the bulk material. This makes them suitable for high-resolution three-photon fluorescence imaging in biomedicine, offering advantages such as strong signal strength, fast imaging speed, and high biosafety.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for stripping CaZnOS semiconductor stress-luminescent two-dimensional materials, comprising the following steps:

[0007] Preparation of CaZnOS bulk materials;

[0008] The CaZnOS bulk material was placed in sodium citrate buffer solution and treated at 60-80℃ to obtain the first product;

[0009] The first product was washed and dried to obtain the second product;

[0010] The second product was placed in an organic solvent, subjected to ultrasonic treatment, centrifuged, and the supernatant was collected to obtain the CaZnOS semiconductor stress-luminescent two-dimensional material.

[0011] Preferably, the second product is placed in an organic solvent and subjected to an ultrasonic treatment step, with an ultrasonic power of 100~600 W, an ultrasonic temperature of 0~5℃, and a pause of 5~7 seconds after each 3~5 seconds of ultrasonic treatment, for a total of 1~10 hours of ultrasonic treatment.

[0012] Preferably, the pH of the sodium citrate buffer solution is 5.0 to 7.0, and the concentration of the sodium citrate buffer solution is 0.1 to 0.3 M.

[0013] Preferably, the organic solvent includes at least one of methanol, ethanol, and isopropanol.

[0014] Preferably, the general chemical formula of the CaZnOS bulk material is CaZnOS: x% M, where x% represents the molar percentage of element M relative to CaZnOS, 0.1≤x≤10, and element M is at least one of Mn, Pr, Nd, Sm, Eu, Dy, Ho, Er, and Yb.

[0015] Preferably, the CaZnOS bulk material is placed in sodium citrate buffer solution and stirred at 60-80°C at a stirring rate of 200-800 rpm for 12-72 h to obtain the first product; the mass-to-volume ratio of the CaZnOS bulk material to the sodium citrate buffer solution is (0.2-0.3) g:(25-35) mL.

[0016] After washing the first product in water, centrifuge at 5000-6000 rpm for 5-15 min, discard the supernatant, collect the bottom precipitate, and dry to obtain the second product.

[0017] Preferably, the second product is placed in an organic solvent and subjected to ultrasonic treatment, centrifuged at 500-1500 rpm for 5-15 min, and the supernatant is collected to obtain the CaZnOS semiconductor stress luminescent two-dimensional material.

[0018] The mass-to-volume ratio of the CaZnOS bulk material to the organic solvent is (0.2~0.3)g:(25~35)mL.

[0019] Preferably, the method for preparing the CaZnOS bulk material includes the following steps:

[0020] After mixing the metal salts corresponding to ZnS and M elements, the mixture is ground to obtain the first mixture.

[0021] Add CaO to the first mixture and continue grinding to obtain the second mixture;

[0022] NaCl was coated on the surface of the second mixture, and sintered at 1050~1100℃ for 4~6h. After natural cooling, the NaCl crystals were removed by washing with water and dried to obtain CaZnOS bulk material.

[0023] Among them, the metal salt corresponding to element M is the carbonate or hydrated chloride of the corresponding metal.

[0024] Secondly, the present invention also provides a CaZnOS semiconductor stress-luminescent two-dimensional material, which is prepared by the exfoliation method described above.

[0025] Thirdly, the present invention also provides a CaZnOS semiconductor stress-luminescent two-dimensional material prepared by the exfoliation method described above, or the application of the CaZnOS semiconductor stress-luminescent two-dimensional material described above in three-photon fluorescence imaging.

[0026] The CaZnOS semiconductor stress-luminescent two-dimensional material and its exfoliation method of the present invention have the following advantages compared with the prior art:

[0027] The present invention discloses a method for exfoliating CaZnOS semiconductor stress-luminescent two-dimensional materials. The method involves treating bulk CaZnOS material in a sodium citrate buffer solution to weaken the interlayer forces through ion chelation and etching, yielding a first product. The first product is then washed to remove impurities and dried to obtain a second product. This second product is then placed in an organic solvent and subjected to ultrasonic exfoliation to effectively exfoliate the bulk CaZnOS material. After centrifugation, the supernatant is collected, yielding the CaZnOS semiconductor stress-luminescent two-dimensional material. This invention represents the first successful exfoliation of strongly bonded bulk CaZnOS material into CaZnOS two-dimensional nanosheets with stress-luminescent properties. Among them, CaZnOS-doped Mn two-dimensional nanosheets have a fluorescence lifetime on the order of nanoseconds, which is six orders of magnitude less than that of bulk materials, reducing it from the millisecond level to the nanosecond level. Due to its unique physical property of nanosecond-level fluorescence lifetime, the resulting two-dimensional nanosheets are suitable for high-resolution three-photon fluorescence imaging in biomedicine. They have the characteristics of strong signal, fast imaging speed, and high biosafety, and can be used as core functional materials to prepare high-sensitivity flexible sensors, low-background biomedical imaging probes, and high-efficiency optoelectronic devices, filling the gap in the application of this material at the nanoscale. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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.

[0029] Figure 1 This is a scanning electron microscope schematic diagram of the CaZnOS:2%Mn semiconductor stress-emitting bulk material prepared by the molten salt method in Example 1 of the present invention;

[0030] Figure 2 This is a transmission electron microscope schematic diagram of the CaZnOS:2%Mn two-dimensional nanosheets finally obtained in Example 1 of the present invention;

[0031] Figure 3 This is an atomic force microscope schematic diagram of the CaZnOS:2%Mn two-dimensional nanosheets finally obtained in Example 1 of the present invention;

[0032] Figure 4 The stress luminescence spectra of CaZnOS:2%Mn semiconductor stress luminescence bulk material and CaZnOS:2%Mn two-dimensional nanosheets in Example 1 of this invention are shown.

[0033] Figure 5The single-particle fluorescence lifetime diagrams of the CaZnOS:2%Mn semiconductor stress-luminescent bulk material and the single-particle fluorescence lifetime diagrams of the CaZnOS:2%Mn two-dimensional nanosheets in Example 1 of the present invention are shown.

[0034] Figure 6 This is a three-photon imaging image of the CaZnOS:2%Mn two-dimensional nanosheet colloidal solution finally obtained in Example 1 of the present invention inside a polytetrafluoroethylene tube (simulating a biological blood vessel) with an inner diameter of 280 μm. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0037] This application provides a method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials, including the following steps:

[0038] S1. Preparation of CaZnOS bulk material;

[0039] S2. Place the CaZnOS bulk material in sodium citrate buffer solution and treat it at 60~80℃ to obtain the first product;

[0040] S3. Wash and dry the first product to obtain the second product;

[0041] S4. Place the second product in an organic solvent, sonicate it, centrifuge it, and collect the supernatant to obtain the CaZnOS semiconductor stress-luminescent two-dimensional material.

[0042] The present invention discloses a method for exfoliating CaZnOS semiconductor stress-luminescent two-dimensional materials. The method involves treating bulk CaZnOS material in a sodium citrate buffer solution to weaken the interlayer forces through ion chelation and etching, yielding a first product. The first product is then washed to remove impurities and dried to obtain a second product. This second product is then placed in an organic solvent and subjected to ultrasonic exfoliation to effectively exfoliate the bulk CaZnOS material. After centrifugation, the supernatant is collected, yielding the CaZnOS semiconductor stress-luminescent two-dimensional material. This invention is the first to achieve the exfoliation of strongly bonded bulk CaZnOS material into CaZnOS two-dimensional nanosheets with stress-luminescent properties. The resulting two-dimensional nanosheets, due to their unique physical properties of nanosecond-level fluorescence lifetime, are suitable for high-resolution three-photon fluorescence imaging in biomedicine. They possess characteristics such as strong signal, fast imaging speed, and high biosafety, and can be used as core functional materials for the fabrication of high-sensitivity flexible sensors, low-background biomedical imaging probes, and high-efficiency optoelectronic devices, filling a gap in the application of this material at the nanoscale.

[0043] In some embodiments, in the step of placing the second product in an organic solvent and performing ultrasonic treatment, the ultrasonic treatment is performed using a probe-type ultrasonic instrument, with an ultrasonic power of 100~600 W, an ultrasonic temperature of 0~5℃, and a pause of 5~7 seconds after each 3~5 seconds of ultrasonic treatment, for a total of 1~10 hours of ultrasonic treatment.

[0044] In some embodiments, the pH of the sodium citrate buffer is 5.0 to 7.0, and the concentration of the sodium citrate buffer is 0.1 to 0.3 M.

[0045] In some embodiments, the organic solvent includes at least one of methanol, ethanol, and isopropanol.

[0046] In some embodiments, the general chemical formula of the CaZnOS bulk material is CaZnOS: x% M, where x% represents the molar percentage of element M relative to CaZnOS, 0.1≤x≤10, and element M is at least one of Mn, Pr, Nd, Sm, Eu, Dy, Ho, Er, and Yb.

[0047] In some embodiments, the CaZnOS bulk material is placed in sodium citrate buffer and stirred at 200-800 rpm for 12-72 h at 60-80°C to obtain the first product; the mass-to-volume ratio of CaZnOS bulk material to sodium citrate buffer is (0.2-0.3) g:(25-35) mL.

[0048] After washing the first product in water, centrifuge at 5000-6000 rpm for 5-15 min, discard the supernatant, collect the bottom precipitate, and dry to obtain the second product.

[0049] In some embodiments, the second product is placed in an organic solvent, subjected to ultrasonic treatment, centrifuged at 500-1500 rpm for 5-15 min, and the supernatant is collected to obtain CaZnOS semiconductor stress luminescent two-dimensional material.

[0050] The mass-to-volume ratio of CaZnOS bulk material to organic solvent is (0.2~0.3)g:(25~35)mL.

[0051] In some embodiments, CaZnOS bulk materials are prepared using a molten salt method, and the particles exhibit a layered stacked growth morphology, providing a structural basis for subsequent exfoliation. Specifically, the preparation of CaZnOS bulk materials using the molten salt method includes the following steps:

[0052] After mixing the metal salts corresponding to ZnS and M elements, the mixture is ground to obtain the first mixture.

[0053] Add CaO to the first mixture and continue grinding to obtain the second mixture;

[0054] NaCl was coated on the surface of the second mixture, and sintered at 1050~1100℃ for 4~6h in air atmosphere. After natural cooling, the NaCl crystals were removed by washing with water and dried to obtain CaZnOS bulk material.

[0055] Among them, the metal salt corresponding to element M is the carbonate or hydrated chloride of the corresponding metal.

[0056] In some embodiments, the metal salts corresponding to ZnS and M elements are mixed and then added to a solvent for grinding to obtain a first mixture; the solvent may be water or ethanol.

[0057] In some embodiments, CaCO3 is placed in a corundum crucible and heated in a muffle furnace at 1000°C for 4 hours to decompose it, thereby obtaining CaO.

[0058] The aforementioned NaCl primarily serves three functions: fluxing agent: lowering the reaction temperature and promoting the formation of the CaZnOS phase; capping layer: molten liquid NaCl encapsulates the sample, reducing the high-temperature decomposition and volatilization of ZnS; and oxidation prevention / atmosphere buffer: isolating the sample to a certain extent in an air atmosphere, reducing excessive oxidation. Based on the same inventive concept, this invention also provides a CaZnOS semiconductor stress-luminescent two-dimensional material, prepared using the aforementioned exfoliation method.

[0059] The CaZnOS semiconductor stress-luminescent two-dimensional material prepared by this invention is a two-dimensional nanosheet with a thickness of less than 10 nm and a lateral dimension of 50 nm to 50 μm.

[0060] Furthermore, when the prepared CaZnOS semiconductor stress-luminescent two-dimensional material is a CaZnOS:Mn two-dimensional nanosheet, its photoluminescence lifetime is in the nanosecond range, which is six orders of magnitude shorter than the phosphorescence lifetime (millisecond range) of the CaZnOS:Mn bulk material. The nanosheet has piezoelectric effect and / or mechanoluminescence properties.

[0061] Based on the same inventive concept, the CaZnOS semiconductor stress-luminescent two-dimensional material prepared by the exfoliation method of the present invention is applied in three-photon fluorescence imaging; the two-dimensional material of the present invention can also be used to prepare high-sensitivity flexible sensors, low-background biomedical imaging probes and high-efficiency optoelectronic devices.

[0062] The following detailed embodiments further illustrate the CaZnOS semiconductor stress-luminescent two-dimensional material and its exfoliation method of this application. This section, in conjunction with specific embodiments, further explains the content of the present invention, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0063] In the following examples, the sodium citrate buffer was purchased from Maclean's reagents, specifically S885299 sodium citrate buffer, with a concentration of 0.5M and a pH of 6.0.

[0064] Example 1

[0065] This embodiment provides a method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials, including the following steps:

[0066] S1. Preparation of CaZnOS:2%Mn semiconductor stress-luminescent bulk material using the molten salt method, specifically including the following steps:

[0067] CaCO3 was placed in a corundum crucible and heated in a muffle furnace at 1000℃ for 4 hours to decompose it, yielding CaO.

[0068] 5g of ZnS and 2mol% MnCl2·4H2O relative to ZnS were thoroughly ground and mixed with ethanol as the dispersion medium to obtain the first mixture.

[0069] The first mixture was dried to evaporate the solvent ethanol, and CaO with an equimolar amount of ZnS was added. The mixture was then ground for another 10 minutes to obtain the second mixture.

[0070] The second mixture was transferred into an alumina crucible and covered with 15g of NaCl. After compaction, it was placed in a high-temperature furnace and sintered at 1050℃ for 4 hours in an air atmosphere. After sintering, it was naturally cooled to room temperature (25℃). The NaCl crystals wrapped in the sample were washed away with deionized water and finally dried at 80℃ to obtain CaZnOS:2%Mn semiconductor stress luminescent bulk material.

[0071] S2. After passing the CaZnOS:2%Mn semiconductor stress luminescent bulk material through a 100-mesh sieve, weigh 0.2g of the bulk material and place it in 25mL of sodium citrate buffer solution. Stir at 600 rpm for 12h at 60℃ to obtain the first product.

[0072] S3. After washing the first product in water, centrifuge at 5000 rpm for 15 min, discard the supernatant, take the bottom precipitate, and dry it at 80℃ to obtain the second product.

[0073] S4. The second product was placed in 25 mL of organic solvent methanol and subjected to ultrasonic treatment. After centrifugation at 500 rpm for 5 min, the supernatant was collected to obtain CaZnOS:2%Mn two-dimensional nanosheets, which are CaZnOS semiconductor stress luminescent two-dimensional materials.

[0074] The ultrasound process involved using a probe-type ultrasound machine. Under conditions of 300 W ultrasound power and 0℃ ultrasound temperature, the ultrasound was performed for 4 seconds followed by a 6-second pause, for a total of 5 hours.

[0075] Example 2

[0076] This embodiment provides a method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials, including the following steps:

[0077] S1. CaZnOS:0.5%Nd semiconductor stress luminescent bulk material was prepared by molten salt method; the specific synthesis method was the same as in Example 1, except that NdCl3·6H2O with a content of 0.5 mol% relative to ZnS was used instead of 2 mol% MnCl2·4H2O, and the other steps were the same as in Example 1.

[0078] S2. After passing the CaZnOS:0.5%Nd semiconductor stress luminescent bulk material through a 100-mesh sieve, weigh 0.2g of the bulk material and place it in 25mL of sodium citrate buffer solution. Stir at 600 rpm for 24h at 65℃ to obtain the first product.

[0079] S3. After washing the first product in water, centrifuge at 5500 rpm for 15 min, discard the supernatant, take the bottom precipitate, and dry it at 80℃ to obtain the second product.

[0080] S4. The second product was placed in 25 mL of organic solvent methanol and subjected to ultrasonic treatment. After centrifugation at 1000 rpm for 10 min, the supernatant was collected to obtain CaZnOS: 0.5%Nd two-dimensional nanosheets, which are CaZnOS semiconductor stress luminescent two-dimensional materials.

[0081] The ultrasound process involved using a probe-type ultrasound machine. Under conditions of 300 W ultrasound power and 0℃ ultrasound temperature, the ultrasound was performed for 4 seconds followed by a 6-second pause, for a total of 5 hours.

[0082] Example 3

[0083] This embodiment provides a method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials, including the following steps:

[0084] S1. CaZnOS:4% Eu semiconductor stress luminescent bulk material was prepared by molten salt method; the specific synthesis method was the same as in Example 1, except that EuCl3·6H2O with a content of 4 mol% relative to ZnS was used instead of 2 mol% MnCl2·4H2O, and the other steps were the same as in Example 1.

[0085] S2. After passing the CaZnOS:4% Eu semiconductor stress luminescent bulk material through a 100-mesh sieve, weigh 0.2g of the bulk material and place it in 25mL of citric acid-sodium citrate buffer solution. Stir at 600 rpm for 48h at 70℃ to obtain the first product.

[0086] S3. After washing the first product in water, centrifuge at 6000 rpm for 15 min, discard the supernatant, take the bottom precipitate, and dry it at 80℃ to obtain the second product.

[0087] S4. The second product was placed in 25 mL of the organic solvent isopropanol and subjected to ultrasonic treatment. After centrifugation at 1500 rpm for 15 min, the supernatant was collected to obtain CaZnOS:4% Eu two-dimensional nanosheets, which are CaZnOS semiconductor stress luminescent two-dimensional materials.

[0088] The ultrasound process involved using a probe-type ultrasound machine. Under conditions of 300 W ultrasound power and 0℃ ultrasound temperature, the ultrasound was performed for 4 seconds followed by a 6-second pause, for a total of 5 hours.

[0089] Example 4

[0090] This embodiment provides a method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials, including the following steps:

[0091] S1. Prepare CaZnOS:4% Ho semiconductor stress luminescent bulk material by molten salt method; the specific synthesis method is the same as in Example 1, except that 4 mol% HoCl3·6H2O relative to ZnS is used instead of 2 mol% MnCl2·4H2O, and the remaining steps are the same as in Example 1.

[0092] S2. After passing the CaZnOS:4% Ho semiconductor stress luminescent bulk material through a 100-mesh sieve, weigh 0.2g of the bulk material and place it in 25mL of citric acid-sodium citrate buffer solution. Stir at 75℃ and 600 rpm for 72h to obtain the first product.

[0093] S3. After washing the first product in water, centrifuge at 5000 rpm for 15 min, discard the supernatant, take the bottom precipitate, and dry it at 80℃ to obtain the second product.

[0094] S4. The second product was placed in 25 mL of organic solvent methanol and subjected to ultrasonic treatment. After centrifugation at 1000 rpm for 10 min, the supernatant was collected to obtain CaZnOS:4% Ho two-dimensional nanosheets, which are CaZnOS semiconductor stress luminescent two-dimensional materials.

[0095] The ultrasound process involved using a probe-type ultrasound machine. Under conditions of 300 W ultrasound power and 0℃ ultrasound temperature, the ultrasound was performed for 4 seconds followed by a 6-second pause, for a total of 5 hours.

[0096] Example 5

[0097] This embodiment provides a method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials, including the following steps:

[0098] S1. Prepare CaZnOS:2% Yb semiconductor stress luminescent bulk material using the molten salt method; the specific synthesis method is the same as in Example 1, except that 2 mol% YbCl3·6H2O relative to ZnS is used instead of 2 mol% MnCl2·4H2O, and the remaining steps are the same as in Example 1.

[0099] S2. After passing the CaZnOS:2% Yb semiconductor stress luminescent bulk material through a 100-mesh sieve, weigh 0.2g of the bulk material and place it in 25mL of citric acid-sodium citrate buffer solution. Stir at 600 rpm for 72h at 80℃ to obtain the first product.

[0100] S3. After washing the first product in water, centrifuge at 6000 rpm for 15 min, discard the supernatant, take the bottom precipitate, and dry it at 80℃ to obtain the second product.

[0101] S4. The second product was placed in 25 mL of organic solvent methanol and subjected to ultrasonic treatment. After centrifugation at 1000 rpm for 15 min, the supernatant was collected to obtain CaZnOS:2% Yb two-dimensional nanosheets, which are CaZnOS semiconductor stress luminescent two-dimensional materials.

[0102] The ultrasound process involved using a probe-type ultrasound machine. Under conditions of 300 W ultrasound power and 0℃ ultrasound temperature, the ultrasound was performed for 4 seconds followed by a 6-second pause, for a total of 5 hours.

[0103] Example 6

[0104] This embodiment provides a method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials, including the following steps:

[0105] S1. Prepare CaZnOS:18% Yb,2% Er semiconductor stress luminescent bulk material using the molten salt method; the specific synthesis method is the same as in Example 1, except that 18 mol% YbCl3·6H2O and 2 mol% ErCl3·6H2O relative to ZnS are used instead of 2 mol% MnCl2·4H2O, and the remaining steps are the same as in Example 1.

[0106] S2. After passing the CaZnOS:18% Yb,2% Er semiconductor stress luminescent bulk material through a 100-mesh sieve, weigh 0.2g of the bulk material and place it in 25mL of citric acid-sodium citrate buffer solution. Stir at 600 rpm for 48h at 70℃ to obtain the first product.

[0107] S3. After washing the first product in water, centrifuge at 5500 rpm for 15 min, discard the supernatant, take the bottom precipitate, and dry it at 80℃ to obtain the second product.

[0108] S4. The second product was placed in 25 mL of organic solvent ethanol and subjected to ultrasonic treatment. After centrifugation at 1500 rpm for 10 min, the supernatant was collected to obtain CaZnOS:18% Yb,2% Er two-dimensional nanosheets, which are CaZnOS semiconductor stress luminescent two-dimensional materials.

[0109] The ultrasound process involved using a probe-type ultrasound machine. Under conditions of 300 W ultrasound power and 0℃ ultrasound temperature, the ultrasound was performed for 4 seconds followed by a 6-second pause, for a total of 5 hours.

[0110] Performance testing

[0111] Figure 1This is a scanning electron microscope (SEM) schematic diagram of the CaZnOS:2%Mn semiconductor stress-emitting bulk material prepared by the molten salt method in Example 1 of this invention; from Figure 1 It can be seen that the CaZnOS:2%Mn semiconductor stress luminescent bulk material has a layered structure.

[0112] Figure 2 This is a transmission electron microscope schematic diagram of the CaZnOS:2%Mn two-dimensional nanosheets finally obtained in Example 1 of the present invention. Figure 2 The final product was a two-dimensional sheet-like CaZnOS:2%Mn with a size distribution of 50 nm to 50 μm.

[0113] Figure 3 This is an atomic force microscope schematic diagram of the CaZnOS:2%Mn two-dimensional nanosheets finally obtained in Example 1 of the present invention.

[0114] from Figure 3 It can be seen that the average thickness of the two-dimensional nanosheets is 1~10nm, proving that they are two-dimensional materials.

[0115] Figure 4 The stress emission spectra of CaZnOS:2%Mn semiconductor stress-luminescent bulk material and CaZnOS:2%Mn two-dimensional nanosheets in Example 1 of this invention are shown.

[0116] Figure 4 As shown, both CaZnOS:2%Mn bulk and two-dimensional nanosheets exhibit stress luminescence under a force of 30N. However, due to the smaller size and larger specific surface area of ​​the two-dimensional nanosheets, the stress luminescence intensity is weaker.

[0117] Figure 5 The CaZnOS:2%Mn semiconductor stress-emitting bulk material in Example 1 of this invention ( Figure 5 The single-particle fluorescence lifetime plot (inner image size bar is 50 μm) of (a) and the single-particle fluorescence lifetime plot (inner image size bar is 500 nm) of CaZnOS:2%Mn two-dimensional nanosheets. Figure 5 In Figure (a), the fluorescence lifetime curves of three randomly selected sites (1, 2, 3) on a single CaZnOS:2%Mn bulk particle are shown. The lifetimes are all in the order of ms, ranging from 0.73 to 1.68 ms. Figure 5 In Figure (b), the fluorescence lifetime curve of any selected point on the CaZnOS:2%Mn two-dimensional nanosheet is shown. The lifetime is on the order of ns, and the lifetime of the entire two-dimensional nanosheet is 1~3 ns.

[0118] Figure 6The image shows a three-photon imaging image of the CaZnOS:2%Mn two-dimensional nanosheet colloidal solution finally obtained in Example 1 of this invention inside a polytetrafluoroethylene tube (simulating a biological blood vessel) with an inner diameter of 280 μm. The excitation wavelength is 900 nm (three low-energy near-infrared photons). The lower right corner shows its fluorescence spectrum, with an emission wavelength of 609 nm and a size bar of 10 μm. Figure 6 Three-photon imaging images of CaZnOS:2%Mn two-dimensional nanosheets demonstrate their applicability in the field of three-photon bioimaging.

[0119] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0120] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials, characterized in that, Includes the following steps: Preparation of CaZnOS bulk materials; The CaZnOS bulk material was placed in sodium citrate buffer solution and treated at 60-80℃ to obtain the first product; The first product was washed and dried to obtain the second product; The second product was placed in an organic solvent, subjected to ultrasonic treatment, centrifuged, and the supernatant was collected to obtain the CaZnOS semiconductor stress-luminescent two-dimensional material.

2. The method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials as described in claim 1, characterized in that, In the step of placing the second product in an organic solvent and performing ultrasonic treatment, the ultrasonic power is 100~600 W, the ultrasonic temperature is 0~5℃, and after each ultrasonic treatment of 3~5 seconds, there is a 5~7 second pause, for a total of 1~10 hours of ultrasonic treatment.

3. The method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials as described in claim 1, characterized in that, The pH of the sodium citrate buffer solution is 5.0~7.0, and the concentration of the sodium citrate buffer solution is 0.1~0.3M.

4. The method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials as described in claim 1, characterized in that, The organic solvent includes at least one of methanol, ethanol, and isopropanol.

5. The method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials as described in claim 1, characterized in that, The general chemical formula of the CaZnOS bulk material is CaZnOS: x% M, where x% represents the molar percentage of element M relative to CaZnOS, 0.1≤x≤10, and element M is at least one of Mn, Pr, Nd, Sm, Eu, Dy, Ho, Er, and Yb.

6. The method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials as described in claim 1, characterized in that, The CaZnOS bulk material was placed in sodium citrate buffer and stirred at 200-800 rpm for 12-72 h at 60-80 °C to obtain the first product. The mass-to-volume ratio of the CaZnOS bulk material to the sodium citrate buffer solution is (0.2~0.3) g:(25~35) mL; After washing the first product in water, centrifuge at 5000-6000 rpm for 5-15 min, discard the supernatant, collect the bottom precipitate, and dry to obtain the second product.

7. The method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials as described in claim 1, characterized in that, The second product was placed in an organic solvent and subjected to ultrasonic treatment. It was then centrifuged at 500-1500 rpm for 5-15 min, and the supernatant was collected to obtain the CaZnOS semiconductor stress-luminescent two-dimensional material. The mass-to-volume ratio of the CaZnOS bulk material to the organic solvent is (0.2~0.3)g:(25~35)mL.

8. The method for peeling off CaZnOS semiconductor stress-luminescent two-dimensional materials as described in claim 5, characterized in that, The method for preparing the CaZnOS bulk material includes the following steps: After mixing the metal salts corresponding to ZnS and M elements, the mixture is ground to obtain the first mixture. Add CaO to the first mixture and continue grinding to obtain the second mixture; NaCl was coated on the surface of the second mixture, and sintered in air at 1050~1100℃ for 4~6h. After natural cooling, the NaCl crystals were removed by washing with water and dried to obtain CaZnOS bulk material. Among them, the metal salt corresponding to element M is the carbonate or chloride of the corresponding metal.

9. A CaZnOS semiconductor stress-luminescent two-dimensional material, characterized in that, It is prepared using the stripping method described in any one of claims 1 to 8.

10. The application of a CaZnOS semiconductor stress-luminescent two-dimensional material prepared by the exfoliation method according to any one of claims 1 to 8, or the CaZnOS semiconductor stress-luminescent two-dimensional material according to claim 9, in three-photon fluorescence imaging.

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