Quantum dot and diamond composite material and preparation method thereof
By grafting quantum dots on the surface of diamond particles, the problem of weak absorption ability of the diamond NV color center structure is solved, stable fluorescence emission under low-power laser excitation is achieved, and the application range of biomedical detection is expanded.
Patent Information
- Application Number
- CN202510785092.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2025-09-30
AI Technical Summary
The diamond NV color center structure has weak absorption ability for specific light, which limits its application in the field of living biomedicine and requires high-power laser equipment for excitation, increasing experimental costs.
By grafting quantum dots on the surface of diamond particles, the distance between the quantum dots and the NV color center structure is less than or equal to 10nm, and surface ligands are used to connect them to form a quantum dot@diamond composite material, which improves the absorption and fluorescence properties.
Stable fluorescence emission is achieved under ultra-low power laser excitation, which expands the application scope of the composite material in the field of magnetic field signal detection of biological samples and improves the detection accuracy.
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Figure CN120718653A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of quantum sensing and biological extremely weak magnetic field imaging technology, and specifically relates to a quantum dot@diamond composite material and a preparation method thereof. Background Art
[0002] Diamond NV color centers, thanks to their electron spin, are sensitive to changes in their external environment and emit stable fluorescence, enabling ultra-precise sensing and detection of physical parameters. Magneto-optical signal changes are currently the most commonly used method for detecting NV centers, with applications in biology, medicine, military, aviation, geology, and other fields.
[0003] However, due to the small size, low density and smooth surface (high reflectivity) of the nitrogen-vacancy center (NV) structure in diamond materials, the NV color center structure has extremely weak absorption ability for specific light and requires high-power laser equipment to excite it. This makes it difficult to directly apply the NV color center structure in living organisms, limiting its further application in the field of living biomedicine and increasing experimental costs. Summary of the Invention
[0004] This application aims to solve at least one of the technical problems existing in the related art.
[0005] Therefore, the first aspect of the present application provides a quantum dot@diamond composite material.
[0006] A second aspect of the present application provides a method for preparing a quantum dot@diamond composite material.
[0007] In view of this, according to the first aspect of an embodiment of the present application, a quantum dot@diamond composite material is proposed, comprising: diamond particles, the diamond particles including an NV color center structure, the diamond particles being provided with a first surface ligand; quantum dots, being provided with a second surface ligand, the second surface ligand being connected to the first surface ligand to graft the quantum dots onto the surface of the diamond particles; wherein the distance between the quantum dots and the corresponding NV color center structure is less than or equal to 10 nm.
[0008] In a possible implementation, in the composite material, the ratio of the number of the quantum dots to the number of the diamond particles is 10:1 to 1000:1.
[0009] In one possible implementation, the diameter of the quantum dots is 3 nm to 10 nm; the diameter of the diamond particles is 30 nm to 70 nm, each of the diamond particles includes 1 to 4 NV color center structures, and the surface of each of the diamond particles is covered with a plurality of the quantum dots.
[0010] In a possible implementation, the fluorescence peak range of the quantum dots is 400 nm to 600 nm, the absorption peak range is 300 nm to 550 nm, and the absorption range is 200 nm to 1000 nm.
[0011] According to a second aspect of an embodiment of the present application, a method for preparing a quantum dot@diamond composite material is proposed, which is used to prepare the quantum dot@diamond composite material as described above. The preparation method includes the following steps: preparing a diamond solution, wherein the diamond solution includes diamond particles provided with a first surface ligand; preparing a quantum dot solution, wherein the quantum dot solution includes quantum dots provided with a second surface ligand; mixing and stirring the quantum dot solution with the diamond solution to connect the first surface ligand with the second surface ligand to obtain the quantum dot@diamond composite material.
[0012] In one possible implementation, the step of preparing a diamond solution includes: preparing diamond particles; dissolving the diamond particles in an ethanol solution, adding a first surface modifier, heating the solution to 55° C. to 65° C. and stirring for 1.5 to 2.5 hours, so that the first surface modifier forms a first surface ligand on the surface of the diamond particles, thereby obtaining a diamond solution; wherein the first surface modifier includes polyvinyl pyrrolidone, carboxyl, hydroxyl, thiol, alkane, or alkene.
[0013] In one possible implementation, the steps of preparing a quantum dot solution include: preparing a cadmium selenide solution, the cadmium selenide solution including cadmium selenide particles; preparing a precursor solution, the precursor solution including a precursor; mixing the cadmium selenide solution, a second surface modifier, oleic acid amide and octadecene, heating the solution to 55°C to 65°C, and venting; after venting, adding the precursor solution, and heating the solution to 240°C to 300°C, and continuously heating for 25 minutes to 35 minutes, so that the precursor is coated on the outside of the cadmium selenide particles to form the quantum dots, and the second surface modifier forms the second surface ligand on the surface of the quantum dots; purifying the solution to obtain the quantum dot solution; wherein the second surface modifier includes oleic acid.
[0014] In one possible implementation, the steps of preparing a cadmium selenide solution include: mixing selenium powder and octadecylamine with octadecene or oleic acid, heating the solution to 130°C to 180°C, and exhausting the gas; after exhausting the gas, heating the solution to 220°C to 260°C, and continuously heating the solution for 2.5 hours to 3.5 hours to obtain a selenium-containing solution; mixing cadmium oxide, oleic acid, and octadecene, heating the solution to 130°C to 180°C, and exhausting the gas; after exhausting the gas, introducing nitrogen into the solution, heating the solution to 220°C to 260°C, making the solution transparent, and obtaining a cadmium-containing solution; mixing and stirring equal volumes of the selenium-containing solution and the cadmium-containing solution to allow the cadmium selenide particles to begin to grow, and after the growth is completed, purifying the solution to obtain a cadmium selenide solution.
[0015] In one possible implementation, a precursor solution is prepared, wherein the precursor solution includes the following steps: mixing zinc oxide, oleic acid, and octadecene, heating the solution to 130° C. to 180° C., and exhausting the gas; after exhausting the gas, heating the solution to 280° C. to 320° C. to make the solution colorless and transparent, and then cooling the solution to 130° C. to 180° C. to obtain a zinc precursor solution; mixing selenium powder with octadecene or trioctylphosphine, heating the solution to 130° C. to 180° C., and exhausting the gas; after exhausting the gas, heating the solution to 2 The method comprises the following steps: preparing a mixture of a prepolymer and a prepolymer at a temperature of 50°C to 270°C, and continuously heating for 3.5h to 4.5h to completely dissolve the selenium powder to obtain a selenium precursor solution; mixing sulfur powder and octadecene, heating the solution to 130°C to 180°C, and exhausting the gas; after exhausting the gas, heating the solution to 150°C to 180°C to completely dissolve the sulfur powder to obtain a sulfur precursor solution; mixing equal volumes of the zinc precursor solution, the selenium precursor solution, and the sulfur precursor solution to obtain the precursor solution, wherein the precursors include a zinc precursor, a selenium precursor, and a sulfur precursor.
[0016] In one possible implementation, the steps of preparing a quantum dot solution include: mixing cadmium oxide powder, zinc oxide powder, a second surface modifier, n-octyl mercaptan and liquid paraffin, heating the solution to 150°C to 170°C under nitrogen conditions, and exhausting the gas; after exhausting the gas, heating the solution to 260°C to 300°C to completely dissolve the cadmium oxide powder and zinc oxide powder to obtain a cadmium precursor solution; dissolving sulfur powder in 1-octadecene and stirring to obtain a sulfur precursor solution; adding the cadmium precursor solution to the sulfur precursor solution to react to form cadmium sulfide particles to obtain the quantum dots, and allowing the second surface modifier to form the second surface ligand on the surface of the quantum dots, wherein the reaction temperature is 280°C to 320°C, and the heating is maintained for 25 minutes to 35 minutes; after the reaction is completed, the solution temperature is lowered to room temperature, and the solution is cleaned and purified to obtain a quantum dot solution; wherein the second surface modifier includes oleic acid.
[0017] The quantum dot@diamond composite material and its preparation method provided in this application can achieve at least the following technical effects:
[0018] In the present application, quantum dots are grafted onto the surface of diamond particles by connecting the second surface ligand to the first surface ligand, so as to sensitize the absorption capacity of the NV color center structure of the diamond through the quantum dots, thereby improving the absorption performance of the composite material. By ensuring that the distance between the quantum dots and the corresponding NV color center structure is less than or equal to 10 nm, the carriers can smoothly transition to the corresponding NV color center structure near the quantum dots, thereby prompting the excitons in the NV color center structure to transition, improving their own fluorescence emission performance, and achieving the improvement of the fluorescence performance of the composite material. The composite material of the present application can also achieve stable fluorescence emission under ultra-low power (less than 500 μW) laser excitation, which expands the application range of the composite material in the field of magnetic field signal detection of biological samples.
[0019] The above general description and the following description are exemplary and explanatory only and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] One or more embodiments are exemplarily described by corresponding drawings. These exemplary descriptions and drawings do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation. In addition,
[0021] Figure 1 A microscopic diagram of a composite material provided by an embodiment of the present disclosure;
[0022] Figure 2 A flow chart of the preparation method provided in the embodiment of the present disclosure;
[0023] Figure 3 Transmission electron microscope (TEM) images of quantum dots provided in the embodiments of the present disclosure;
[0024] Figure 4 Transmission electron microscope (TEM) images of diamond particles provided in the embodiments of the present disclosure;
[0025] Figure 5 Transmission electron microscope (TEM) images of the composite materials provided in the embodiments of the present disclosure;
[0026] Figure 6 A surface scanning spectrum of the fluorescence signal of the composite material provided in the embodiment of the present disclosure;
[0027] Figure 7 Schematic diagram of the absorption spectrum of each material provided in the embodiment of the present disclosure within the wavelength range of 200nm to 800nm.
[0028] The reference numerals indicate:
[0029] 1: Quantum dot@diamond particle; 10: Diamond particle; 11: NV color center structure; 20: Quantum dot; 30: First surface ligand; 40: Second surface ligand. DETAILED DESCRIPTION
[0030] In order to provide a more detailed understanding of the features and technical content of the embodiments of the present disclosure, the implementation of the embodiments of the present disclosure is described in detail below with reference to the accompanying drawings. The accompanying drawings are for reference only and are not intended to limit the embodiments of the present disclosure. In the following technical description, for the sake of convenience of explanation, multiple details are provided to provide a full understanding of the disclosed embodiments. However, one or more embodiments can still be implemented without these details.
[0031] In the description and claims of the embodiments of the present disclosure and the accompanying drawings, the terms "first," "second," and the like are used to distinguish similar items and are not necessarily used to describe a particular order or precedence. Furthermore, the terms "including," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions.
[0032] Unless otherwise stated, the term "plurality" means two or more.
[0033] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure can be combined with each other.
[0034] Combine Figure 1 and Figure 5 As shown, according to a first aspect of an embodiment of the present application, a quantum dot@diamond composite material is provided, comprising diamond particles 10 and quantum dots 20. The diamond particles 10 include NV color center structures 11. The diamond particles 10 are provided with first surface ligands 30. The quantum dots 20 are provided with second surface ligands 40. The second surface ligands 40 are connected to the first surface ligands 30 to graft the quantum dots 20 onto the surface of the diamond particles 10. The distance between the quantum dots 20 and the corresponding NV color center structures 11 is less than or equal to 10 nm.
[0035] The quantum dots 20 are grafted onto the surface of the diamond particles 10 by connecting the second surface ligands 40 with the first surface ligands 30, forming a composite material having quantum dots@diamond particles 1. The absorption capacity of the NV color center structure 11 of the diamond is sensitized by the quantum dots 20, thereby improving the absorption performance of the composite material. Figure 5As shown, the inside of the dotted circle represents the diamond particle 10 in the quantum dot@diamond particle 1, and the outside of the dotted circle represents the multiple quantum dots 20 in the quantum dot@diamond particle 1. Since the distance between the quantum dot 20 and the corresponding NV color center structure 11 is less than or equal to 10 nm, carriers can smoothly transfer from the vicinity of the quantum dot 20 to the corresponding NV color center structure 11, prompting excitons in the corresponding NV color center structure 11 to transition, thereby enhancing the fluorescence emission performance of the composite material.
[0036] Specifically, the wide bandgap quantum dot 20 material is grafted onto the surface of the diamond particle 10 by surface ligand modification, and the distance between the quantum dot 20 and the corresponding NV color center structure 11 is made less than or equal to 10 nm to form a composite material. The absorption performance of the close-range NV color center structure 11 is improved through the surface plasmon resonance effect, the exciton transfer effect, and the Foster energy transfer effect, so that stable fluorescence emission can be achieved under ultra-low power (less than 500 μW) laser excitation, thereby expanding the application field of the composite material. In the description of the embodiments of the present disclosure, the composite material is an abbreviation of quantum dot@diamond composite material, which will not be repeated below.
[0037] More specifically, the composite material of this embodiment, based on the strong absorption ability of the quantum dot 20 material, absorbs a weak light source to generate photogenerated carriers. The carriers will undergo transition near the quantum dot 20 and transfer to the corresponding NV color center structure 11, prompting the excitons in the NV color center structure 11 to undergo transition, thereby improving its own fluorescence emission performance. This process is the process of quantum dots 20 sensitizing the NV color center structure 11 to absorb.
[0038] The composite material of this embodiment enhances the light absorption capability of the NV color center structure 11. Comparing this composite material with diamond NV color center materials in related art, the composite material of this embodiment improves absorption performance by 2 to 6 times within the 400 nm to 600 nm wavelength range and fluorescence emission performance by 1 to 2 times within the 600 nm to 800 nm wavelength range. In practical applications, this can enhance the signal strength received by the composite material in sensors, improving sensor sensitivity and accuracy.
[0039] For example, if the composite material is placed inside a biological cell, a weak laser light source can be used to detect changes in magnetic signals inside the cell, thereby improving detection accuracy and providing a new feasible solution for understanding the biological microscopic world through precision sensing.
[0040] In a possible implementation, the distance between the quantum dot 20 and the corresponding NV color center structure 11 is 2 nm to 10 nm.
[0041] In a possible implementation, the distance between the quantum dot 20 and the corresponding NV color center structure 11 is 3 nm to 10 nm.
[0042] In a possible implementation, the distance between the quantum dot 20 and the corresponding NV color center structure 11 is 2 nm, 3 nm, 5 nm, 8 nm or 10 nm.
[0043] In one possible implementation, the quantum dots 20 are wide-bandgap quantum dots 20. By sensitizing the diamond NV color center structure 11 with the wide-bandgap quantum dots 20, the absorption performance of the NV color center structure 11 can be greatly improved, thereby improving the absorption and fluorescence properties of the composite material.
[0044] In a possible implementation, the material of the quantum dots 20 includes cadmium (Cd), carbon, perovskite, or phosphorus.
[0045] In some embodiments, in the composite material, the ratio of the number of quantum dots 20 to the number of diamond particles 10 is 10:1 to 1000:1.
[0046] By setting the ratio of the number of quantum dots 20 to the number of diamond particles 10 to be 10:1 to 1000:1, the surface of each diamond particle 10 can be coated with multiple quantum dots 20, so that the number of quantum dots 20 and the number of diamond particles 10 form a good match, thereby improving the absorption and fluorescence properties of the composite material.
[0047] In a specific example, the absorption and fluorescence properties of a composite material having a ratio of the number of quantum dots 20 to the number of diamond particles 10 of 10:1 to 50:1 were tested, and the following results were obtained: Figure 6 The fluorescence signal surface scan spectrum is shown. Figure 6 The signal in the middle is the fluorescence signal of the composite material, and the signal gradually increases from blue to red. Figure 6 The red signal in the image is the site of the NV color center structure 11 of the composite material. It is obvious that the signal of the NV color center structure 11 of the composite material is stronger than that of other regions. Therefore, the composite material of this embodiment can effectively improve the absorption and fluorescence properties of the material.
[0048] As another specific example, composite material 1, composite material 2, composite material 3, composite material 4 and diamond material (including pure diamond particles) are prepared. Among them, in composite material 1, the ratio of the number of quantum dots 20 particles to the number of diamond particles 10 particles is 100:1. In composite material 2, the ratio of the number of quantum dots 20 particles to the number of diamond particles 10 particles is 200:1. In composite material 3, the ratio of the number of quantum dots 20 particles to the number of diamond particles 10 particles is 400:1. In composite material 4, the ratio of the number of quantum dots 20 particles to the number of diamond particles 10 particles is 800:1. Composite material 1, composite material 2, composite material 3, composite material 4 and diamond material are tested, and the following is obtained. Figure 7 The absorption spectrum of each material in the wavelength range of 200 nm to 800 nm is shown.
[0049] Combine Figure 7 As shown, within the wavelength range of 200nm to 800nm, the absorbance of the diamond material gradually decreases, that is, the absorption range of the diamond particles within the wavelength range of 200nm to 800nm is relatively low. However, the absorption range of composite material 1, composite material 2, composite material 3, and composite material 4 within the wavelength range of 200nm to 800nm is relatively high. Moreover, as the ratio of the number of particles of quantum dots 20 to the number of particles of diamond particles 10 in the composite material gradually increases, the absorption peak gradually increases, and the absorption performance gradually improves. Therefore, grafting quantum dots 20 onto diamond particles 10 can effectively improve the absorption performance of the material, so as to enable the material to be used in an ultra-low power (less than 500μW) laser excitation environment.
[0050] In a possible implementation, the ratio of the number of quantum dots 20 to the number of diamond particles 10 is 10:1, 100:1, 200:1, 400:1, 800:1, or 1000:1.
[0051] Combine Figures 3 to 5 As shown, in some embodiments, the diameter of the quantum dot 20 is 3 nm to 10 nm. The diameter of the diamond particle 10 is 30 nm to 70 nm. Each diamond particle 10 includes 1 to 4 NV color center structures 11. The surface of each diamond particle 10 is coated with multiple quantum dots 20.
[0052] Combine Figure 3 As shown, the diameter of the quantum dots 20 is 3nm to 10nm, and they are dot-shaped and uniform in size. Figure 4 As shown, the diameter of the diamond particles 10 is 30nm to 70nm, and they are in a flake structure. Figure 5 As shown, the surface of each diamond particle 10 is coated with a plurality of quantum dots 20 .
[0053] The diameter of the quantum dots 20 is 3nm to 10nm, the diameter of the diamond particles 10 is 30nm to 70nm, each diamond particle 10 includes 1 to 4 NV color center structures 11, the surface of each diamond particle 10 is covered with multiple quantum dots 20, and the ratio of the number of quantum dots 20 to the number of diamond particles 10 is 10:1 to 1000:1. The ratio of quantum dots 20 to diamond particles 10 in the composite material is optimized, thereby further improving the absorption and fluorescence properties of the composite material.
[0054] In some embodiments, the fluorescence peak of quantum dots 20 ranges from 400 nm to 600 nm, the absorption peak of quantum dots 20 ranges from 300 nm to 550 nm, and the absorption range of quantum dots 20 ranges from 200 nm to 1000 nm. Therefore, quantum dots 20 are wide-bandgap quantum dots 20, which can better sensitize the NV color center structure 11 of diamond.
[0055] Combine Figure 2 As shown, according to the second aspect of the embodiment of the present application, a method for preparing a quantum dot@diamond composite material is provided, which is used to prepare the quantum dot@diamond composite material as described above. The preparation method comprises the following steps:
[0056] S201. Prepare a diamond solution, wherein the diamond solution includes diamond particles provided with a first surface ligand.
[0057] By preparing a diamond solution, the diamond solution includes diamond particles 10 provided with first surface ligands 30 , thereby providing ligand preparation for grafting the quantum dots 20 onto the diamond particles 10 .
[0058] S202, preparing a quantum dot solution, wherein the quantum dot solution includes quantum dots provided with a second surface ligand.
[0059] By preparing a quantum dot 20 solution, the quantum dot 20 solution includes quantum dots 20 provided with second surface ligands 40 , thereby providing ligand preparation for grafting the quantum dots 20 onto the diamond particles 10 .
[0060] S203 , mixing the quantum dot solution and the diamond solution and stirring them to connect the first surface ligand with the second surface ligand to obtain a quantum dot@diamond composite material.
[0061] By mixing and stirring the quantum dot 20 solution with the diamond solution, the first surface ligand 30 and the second surface ligand 40 are adsorbed and connected, thereby achieving the quantum dot 20 being grafted onto the surface of the diamond particle 10 .
[0062] During actual preparation, after the quantum dot 20 solution is mixed with the diamond solution, the rotation speed can be increased and the mixture can be stirred vigorously to allow the multiple quantum dots 20 to be more evenly grafted onto the surface of the diamond particles 10 .
[0063] In this embodiment, after the quantum dot 20 solution and the diamond solution are mixed and stirred, the solution can be purified by ultrasound and centrifugation to obtain a composite material of target purity. The composite material is then dissolved in ethanol and stored for future use.
[0064] Among them, the method of purifying the solution by ultrasound and centrifugation is not limited, for example: take 5mL of solution (a mixture of quantum dot 20 solution and diamond solution), put it into a 50mL centrifuge tube, and add 35mL of acetone. Centrifuge it through a centrifuge with a centrifugal speed of 2000r / min and a centrifugal time of 10min. After centrifugation, leave the centrifuged precipitate, add 50mL of deionized water, and perform ultrasonic dispersion. Then, continue to centrifuge it through a centrifuge with a centrifugal speed of 2000r / min and a centrifugal time of 10min. After centrifugation, take out the precipitate, add 5mL of ethanol, and save it for later use.
[0065] In some embodiments, the step of preparing a diamond solution includes preparing diamond particles 10, dissolving the diamond particles 10 in an ethanol solution, adding a first surface modifier, heating the solution to 55° C. to 65° C. and stirring for 1.5 to 2.5 hours to allow the first surface modifier to form first surface ligands 30 on the surfaces of the diamond particles 10, thereby obtaining a diamond solution. The first surface modifier includes polyvinyl pyrrolidone, a carboxyl group, a hydroxyl group, a thiol, an alkane, or an alkene.
[0066] By dissolving the diamond particles 10 in an ethanol solution, adding a first surface modifier, heating the solution to 55°C to 65°C and stirring for 1.5h to 2.5h, the first surface modifier is attached to the surface of the diamond particles 10 to form a first surface ligand 30, thereby achieving surface ligand modification of the surface of the diamond particles 10 for adsorption with the second surface ligand 40 on the surface of the quantum dots 20, so as to achieve grafting of the quantum dots 20 onto the surface of the diamond particles 10.
[0067] A specific application example is a method for preparing a composite material, comprising the following steps:
[0068] Diamond particles 10 are prepared. The diamond particles 10 may be nanodiamond particles 10. The diameter of the diamond particles 10 is 30 nm to 70 nm, wherein each diamond particle 10 includes 1 to 4 NV color center structures 11.
[0069] In a 20mL beaker, dissolve 5mg-20mg of diamond particles 10 in 1mL-5mL of ethanol. Add 10mg-100mg of polyvinylpyrrolidone (PVP, molecular weight less than 4W) to the beaker. Heat the solution to 60°C and stir for 2 hours. This allows the first surface modifier to form first surface ligands 30 on the surfaces of the diamond particles 10, yielding a diamond solution.
[0070] Then, 1 mL to 2 mL of the quantum dot 20 solution is added to the beaker, and the rotation speed is increased and stirred vigorously to allow the multiple quantum dots 20 to be evenly adsorbed on the surface of the diamond particles 10 .
[0071] Finally, the solution is purified by ultrasound and centrifugation to extract the composite material of target purity, and the composite material is dissolved in ethanol and stored for future use.
[0072] In some embodiments, the step of preparing a quantum dot 20 solution includes: preparing a cadmium selenide solution, the cadmium selenide solution including cadmium selenide particles. Preparing a precursor solution, the precursor solution including a precursor. Mixing the cadmium selenide solution, the second surface modifier, oleic acid amide and octadecene, heating the solution to 55°C to 65°C, and exhausting the gas. After exhausting, adding the precursor solution, and heating the solution to 240°C to 300°C, and continuously heating for 25min to 35min, so that the precursor is coated on the outside of the cadmium selenide particles to form quantum dots 20, and the second surface modifier forms a second surface ligand 40 on the surface of the quantum dots 20. Purifying the solution to obtain a quantum dot 20 solution. Wherein, the second surface modifier includes oleic acid.
[0073] The cadmium selenide solution can be understood as a nano-solution, and the cadmium selenide particles can be understood as the core layer of the nanocrystal. That is, the cadmium selenide particles provide the core layer of the quantum dot 20 (i.e., the nanocrystal). The precursor solution provides a shell layer, which can be coated on the outside of the cadmium selenide particles to form a core-shell structure, that is, forming the quantum dot 20, thereby optimizing the luminescence and stability of the quantum dot 20.
[0074] The method comprises mixing a cadmium selenide solution, a second surface modifier, oleic acid amide, and octadecene, heating the solution to 55° C. to 65° C., and venting the solution. After venting, a precursor solution is added, and the solution is heated to 240° C. to 300° C. and heated for 25 to 35 minutes. The precursor is coated on the outside of the cadmium selenide particles to form quantum dots 20, and the quantum dots 20 are wide-bandgap quantum dots 20. The second surface modifier forms second surface ligands 40 on the surface of the quantum dots 20. That is, Cd-based wide-bandgap quantum dots 20 are synthesized by a solution method to obtain wide-bandgap quantum dots 20 with a wide absorption range based on the Cd system, thereby improving the effect of sensitizing the NV color center structure 11 of the diamond.
[0075] The second surface modifier includes but is not limited to oleic acid, which can enable the second surface ligands 40 formed by the second surface modifier to be adsorbed with the first surface ligands 30 to graft the quantum dots 20 onto the diamond particles 10 .
[0076] The solution is purified to obtain quantum dots 20 of target purity, and then the quantum dots 20 are dissolved in n-hexane for storage to obtain a quantum dot 20 solution, in preparation for sensitizing the diamond NV color center structure 11.
[0077] In practical applications, wide-bandgap quantum dots 20 with a wide absorption range based on carbon can also be synthesized, and can also be used to prepare the composite material of this embodiment.
[0078] In some embodiments, the step of preparing a cadmium selenide solution includes: mixing selenium powder and octadecylamine with octadecene or oleic acid, heating the solution to 130°C to 180°C, and exhausting the gas. After exhausting, the solution is heated to 220°C to 260°C, and the heating is continued for 2.5h to 3.5h to obtain a selenium-containing solution. Cadmium oxide, oleic acid and octadecene are mixed, and the solution is heated to 130°C to 180°C, and the gas is exhausted. After exhausting, nitrogen is introduced into the solution, and the solution is heated to 220°C to 260°C to make the solution transparent to obtain a cadmium-containing solution. Equal volumes of selenium-containing solution and cadmium-containing solution are mixed and stirred to allow cadmium selenide particles to begin to grow. After the growth is completed, the solution is purified to obtain cadmium selenide particles of the target purity. The purified cadmium selenide particles are dissolved in hexane and stored to obtain a cadmium selenide solution.
[0079] The selenium-containing solution of the target component is obtained by mixing selenium powder, octadecylamine and octadecene or oleic acid, heating the solution to 130° C. to 180° C. and exhausting the gas. After exhausting the gas, the solution is heated to 220° C. to 260° C. and continuously heated for 2.5 hours to 3.5 hours.
[0080] The method comprises the following steps: mixing cadmium oxide, oleic acid and octadecene, heating the solution to 130 to 180° C., exhausting the gas, introducing nitrogen after exhausting the gas, heating the solution to 220 to 260° C., making the solution transparent, and obtaining a cadmium-containing solution of the target component.
[0081] Equal volumes of a selenium-containing solution and a cadmium-containing solution are mixed, i.e., the selenium-containing solution and the cadmium-containing solution are mixed in a volume ratio of 1:1. The mixing and stirring process causes cadmium selenide particles to begin growing. After growth is complete, the solution is purified to obtain cadmium selenide particles of the target purity. The purified cadmium selenide particles are dissolved in hexane and stored to obtain a cadmium selenide solution for subsequent use.
[0082] In a possible implementation, when the selenium-containing solution and the cadmium-containing solution of equal volume are stirred, the stirring speed is 500 r / min to 1000 r / min.
[0083] In some embodiments, a precursor solution is prepared, and the precursor solution includes the following steps: mixing zinc oxide, oleic acid and octadecene, heating the solution to 130°C to 180°C, and exhausting. After exhausting, the solution is heated to 280°C to 320°C to make the solution colorless and transparent, and the solution is cooled to 130°C to 180°C to obtain a zinc precursor solution. Selenium powder is mixed with octadecene or trioctylphosphine, and the solution is heated to 130°C to 180°C and exhausted. After exhausting, the solution is heated to 250°C to 270°C and continuously heated for 3.5h to 4.5h to completely dissolve the selenium powder to obtain a selenium precursor solution. Sulfur powder and octadecene are mixed, the solution is heated to 130°C to 180°C, and exhausted. After exhausting, the solution is heated to 150° C. to 180° C. to completely dissolve the sulfur powder to obtain a sulfur precursor solution; equal volumes of zinc precursor solution, selenium precursor solution and sulfur precursor solution are mixed to obtain a precursor solution, wherein the precursors include a zinc precursor, a selenium precursor and a sulfur precursor.
[0084] The method comprises mixing zinc oxide, oleic acid and octadecene, heating the solution to 130° C. to 180° C. and exhausting the gas. After exhausting the gas, the solution is heated to 280° C. to 320° C. to make the solution colorless and transparent. The solution is then cooled to 130° C. to 180° C. to obtain a zinc precursor solution of the target component.
[0085] The method comprises mixing selenium powder with octadecene or trioctylphosphine, heating the solution to 130° C. to 180° C., and exhausting the gas. After exhausting the gas, the solution is heated to 250° C. to 270° C., and continuously heated for 3.5 hours to 4.5 hours to completely dissolve the selenium powder, thereby obtaining a selenium precursor solution of the target component.
[0086] The sulfur powder and octadecene are mixed, the solution is heated to 130° C. to 180° C., and the gas is exhausted. After exhausting, the solution is heated to 150° C. to 180° C. to completely dissolve the sulfur powder, thereby obtaining a sulfur precursor solution of the target component.
[0087] Equal volumes of a zinc precursor solution, a selenium precursor solution, and a sulfur precursor solution are mixed, that is, the zinc precursor solution, the selenium precursor solution, and the sulfur precursor solution are mixed in a volume ratio of 1:1:1. A precursor solution of a target component is obtained by mixing equal volumes of the zinc precursor solution, the selenium precursor solution, and the sulfur precursor solution, and the precursor includes a zinc precursor, a selenium precursor, and a sulfur precursor.
[0088] A specific application example is a method for preparing a quantum dot 20 solution, comprising the following steps:
[0089] Step 1: prepare a cadmium selenide solution.
[0090] Prepare a selenium solution: Add 0.1g–0.5g of selenium (Se) powder, 1mg–2mg of octadecylamine (ODA), and 10mL–25mL of octadecene (ODE) to a 50mL three-necked flask and mix. Heat the solution to 150°C and vent for 20 minutes. After venting, heat the solution to 240°C and continue heating for 3 hours. Oleic acid can be used instead of octadecene (ODE).
[0091] Prepare a cadmium solution: Add 0.01g-0.03g of cadmium oxide (CdO), 0.1g-0.5g of oleic acid (OA), and 2.0g-4.0g of octadecene to a 25mL three-necked flask and mix. Heat the solution to 150°C and vent for 20 minutes. After venting, introduce nitrogen into the solution and heat to 240°C until the solution becomes transparent, thereby obtaining a cadmium solution.
[0092] Prepare a cadmium selenide solution: Mix a selenium-containing solution and a cadmium-containing solution in a 1:1 volume ratio and stir to allow cadmium selenide particles to grow. After growth is complete, purify the solution with methanol and hexane to obtain cadmium selenide particles of the target purity. Finally, dissolve the purified cadmium selenide particles in hexane to obtain a cadmium selenide solution. The volumes of the selenium-containing solution and the cadmium-containing solution are 1 mL to 5 mL, respectively.
[0093] Step 2: Prepare the precursor solution.
[0094] Prepare a zinc (Zn) precursor solution: Add 1.0g to 3.0g of zinc oxide (ZnO), 10mL to 30mL of oleic acid, and 10mL to 30mL of octadecene to a 100mL three-necked flask and mix. Heat the solution to 150°C and vent for 15 minutes. After venting, heat the solution to 300°C until the solution becomes colorless and transparent. Then cool the solution to 150°C to obtain a zinc precursor solution.
[0095] Prepare a selenium precursor solution: Combine 1.0-2.0g of selenium (Se) powder and 30-50mL of octadecene in a 100mL three-necked flask. Heat the solution to 150°C and vent for 20 minutes. After venting, heat the solution to 260°C for 4 hours to completely dissolve the selenium powder, resulting in a selenium precursor solution. The 30-50mL of octadecene can be replaced with 10-30mL of trioctylphosphine (TOP).
[0096] Prepare a sulfur precursor solution: Add 0.01g-0.05g of sulfur (S) powder and 30mL-50mL of octadecene to a 100mL three-necked flask. Heat the solution to 150°C and vent for 20 minutes. After venting, heat the solution to 180°C to completely dissolve the sulfur powder, thereby obtaining a sulfur precursor solution.
[0097] Equal volumes of a zinc precursor solution, a selenium precursor solution and a sulfur precursor solution are mixed to obtain a precursor solution, wherein the precursors include a zinc precursor, a selenium precursor and a sulfur precursor.
[0098] Step 3: Covering the outside of the cadmium selenide particles with the precursor.
[0099] Mix 3 mL to 5 mL of cadmium selenide solution, 3 mL to 5 mL of oleic acid, 3 mL to 5 mL of oleamide, and 5 mL to 10 mL of octadecene. Heat the solution to 60°C and vent for 15 minutes to remove volatile substances. Add 1 mL to 4 mL of the precursor solution, mix, and heat the solution to 280°C for 30 minutes. This will coat the cadmium selenide particles with the precursor.
[0100] Step 4: purification and preservation.
[0101] 5 mL of the solution (the solution obtained in step 3) was placed in a 50 mL centrifuge tube, 35 mL of acetone was added, and the tube was centrifuged at a speed of 6000 r / min for 5 min.
[0102] After centrifugation, add 5 mL of n-octane and ultrasonically disperse the precipitate. After ultrasonic dispersion, centrifuge the precipitate at 6000 rpm for 5 minutes. After centrifugation, retain the supernatant.
[0103] 5 mL of ethanol was added and the mixture was centrifuged at 6000 rpm for 3 min. After centrifugation, the precipitate was removed and stored in 3 mL of n-hexane for later use.
[0104] In some embodiments, the step of preparing a quantum dot 20 solution includes: mixing cadmium oxide powder, zinc oxide powder, a second surface modifier, n-octyl mercaptan and liquid paraffin, heating the solution to 150°C to 170°C under nitrogen conditions, and exhausting. After exhausting, the solution is heated to 260°C to 300°C to completely dissolve the cadmium oxide powder and zinc oxide powder to obtain a cadmium precursor solution. Sulfur powder is dissolved in 1-octadecene and stirred to obtain a sulfur precursor solution. The cadmium precursor solution is added to the sulfur precursor solution to react to form cadmium sulfide particles to obtain quantum dots 20, and the second surface modifier forms a second surface ligand 40 on the surface of the quantum dots 20, wherein the reaction temperature is 280°C to 320°C and the heating is maintained for 25 minutes to 35 minutes. After the reaction is completed, the solution temperature is reduced to room temperature, and it is cleaned and purified to obtain a quantum dot 20 solution. The second surface modifier includes oleic acid.
[0105] In this embodiment, a precursor solution containing the target cadmium component is obtained by mixing cadmium oxide powder, zinc oxide powder, a second surface modifier, n-octyl mercaptan, and liquid paraffin. The solution is heated to 150°C to 170°C under nitrogen and then vented. After venting, the solution is heated to 260°C to 300°C to completely dissolve the cadmium oxide and zinc oxide powders. The second surface modifier includes, but is not limited to, oleic acid, which can form a second surface ligand 40 that can be successfully adsorbed and bonded to the first surface ligand 30.
[0106] In this embodiment, a precursor solution of sulfur of the target component is obtained by dissolving sulfur powder in 1-octadecene and stirring.
[0107] The cadmium precursor solution is added to the cadmium precursor solution to react, and the reaction temperature is set at 280°C to 320°C and maintained for 25 to 35 minutes to form cadmium sulfide particles. That is, quantum dots 20 are obtained, and the second surface modifier forms second surface ligands 40 on the surface of the quantum dots 20. After the reaction is completed, the solution temperature is lowered to room temperature (e.g., 20°C to 25°C), and the solution is cleaned and purified to obtain a quantum dot 20 solution for future use.
[0108] Another specific application example is a method for preparing a quantum dot 20 solution, comprising the following steps:
[0109] Place 30mg to 60mg of cadmium oxide (CdO) powder, 5mg to 10mg of zinc oxide (ZnO) powder, 3g to 8g of oleic acid (OA, 90% purity), 0.5mL to 2mL of n-octyl mercaptan (OT, 98% purity), and 15mL to 30mL of liquid paraffin in a 100mL three-necked flask and mix. Under nitrogen conditions, heat the solution to 160°C and vent for 30 minutes. After venting, heat the solution to 280°C to completely dissolve the cadmium oxide and zinc oxide powders (for example, wait about 1 hour for the solution to become clear, i.e., the powders are completely dissolved), to obtain a cadmium precursor solution.
[0110] 10 mg to 20 mg of sulfur powder is dissolved in 2 mL to 4 mL of 1-octadecene (ODE, purity 90%), and the mixture is stirred to form a solution to obtain a sulfur precursor solution.
[0111] The cadmium precursor solution is quickly added (which can be understood as pouring it all at once) to the sulfur precursor solution (which can be mixed in a three-necked flask) for reaction, and the solution is heated to a reaction temperature of 300°C and maintained for 30 minutes to obtain quantum dots 20 (i.e., cadmium sulfide particles), and the second surface modifier forms a second surface ligand 40 on the surface of the quantum dots 20.
[0112] After the reaction is completed, the solution is cooled to room temperature and washed and purified with methanol and acetone to obtain quantum dots 20 of target purity. The quantum dots 20 are dissolved in n-octane solution and stored for future use.
[0113] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application. The above are merely preferred embodiments of the present application. It should be noted that those skilled in the art may make various improvements and variations without departing from the technical principles of the present application, and such improvements and variations shall also be considered within the scope of protection of the present application.
Claims
1. A quantum dot@diamond composite material, characterized in that: include: A diamond particle comprising an NV color center structure, wherein the diamond particle is provided with a first surface ligand; A quantum dot having a second surface ligand connected to the first surface ligand to graft the quantum dot onto the surface of the diamond particle; Wherein, the distance between the quantum dot and the corresponding NV color center structure is less than or equal to 10 nm.
2. The composite material according to claim 1, characterized in that In the composite material, the ratio of the number of the quantum dots to the number of the diamond particles is 10:1 to 1000:
1.
3. The composite material according to claim 1, characterized in that The diameter of the quantum dots is 3 nm to 10 nm; The diameter of the diamond particles is 30 nm to 70 nm, each of the diamond particles includes 1 to 4 NV color center structures, and the surface of each diamond particle is coated with a plurality of quantum dots.
4. The composite material according to claim 1, characterized in that The fluorescence peak range of the quantum dots is 400nm to 600nm, the absorption peak range is 300nm to 550nm, and the absorption range is 200nm to 1000nm.
5. A method for preparing a quantum dot@diamond composite material, for preparing the quantum dot@diamond composite material according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: preparing a diamond solution comprising diamond particles provided with first surface ligands; preparing a quantum dot solution comprising quantum dots provided with a second surface ligand; The quantum dot solution and the diamond solution are mixed and stirred to connect the first surface ligand and the second surface ligand to obtain the quantum dot@diamond composite material.
6. The preparation method according to claim 5, characterized in that The steps for preparing diamond solution include: preparing diamond particles; dissolving the diamond particles in an ethanol solution, adding a first surface modifier, heating the solution to 55° C. to 65° C. and stirring for 1.5 to 2.5 hours, so that the first surface modifier forms the first surface ligand on the surface of the diamond particles, thereby obtaining the diamond solution; Wherein, the first surface modification substance includes polyvinyl pyrrolidone, carboxyl, hydroxyl, thiol, alkane or alkene.
7. The preparation method according to claim 5, characterized in that The steps of preparing the quantum dot solution include: preparing a cadmium selenide solution, wherein the cadmium selenide solution comprises cadmium selenide particles; preparing a precursor solution, wherein the precursor solution includes a precursor; The cadmium selenide solution, the second surface modifier, oleic acid amide and octadecene are mixed, and the solution is heated to 55° C. to 65° C. and vented; after venting, the precursor solution is added, and the solution is heated to 240° C. to 300° C. and continuously heated for 25 min to 35 min, so that the precursor is coated on the outside of the cadmium selenide particles to form the quantum dots, and the second surface modifier forms the second surface ligand on the surface of the quantum dots; the solution is purified to obtain the quantum dot solution; Wherein, the second surface modifier includes oleic acid.
8. The preparation method according to claim 7, characterized in that The steps of preparing the cadmium selenide solution include: Selenium powder and octadecylamine are mixed with octadecene or oleic acid, and the solution is heated to 130° C. to 180° C. and vented; after venting, the solution is heated to 220° C. to 260° C. and continuously heated for 2.5 hours to 3.5 hours to obtain a selenium-containing solution; Mixing cadmium oxide, oleic acid and octadecene, heating the solution to 130° C. to 180° C., and exhausting the gas; after exhausting the gas, introducing nitrogen into the solution, and heating the solution to 220° C. to 260° C. to make the solution transparent, thereby obtaining a cadmium-containing solution; The selenium-containing solution and the cadmium-containing solution of equal volume are mixed and stirred to allow cadmium selenide particles to begin to grow. After the growth is completed, the solution is purified to obtain a cadmium selenide solution.
9. The preparation method according to claim 7, characterized in that The steps of preparing a precursor solution, wherein the precursor solution includes a precursor include: Mix zinc oxide, oleic acid and octadecene, heat the solution to 130° C. to 180° C., and exhaust the gas; after exhausting the gas, heat the solution to 280° C. to 320° C. to make the solution colorless and transparent, and then cool the solution to 130° C. to 180° C. to obtain a zinc precursor solution; Mixing selenium powder with octadecene or trioctylphosphine, heating the solution to 130° C. to 180° C. and exhausting the gas; after exhausting the gas, heating the solution to 250° C. to 270° C. and continuing heating for 3.5 hours to 4.5 hours to completely dissolve the selenium powder, thereby obtaining a selenium precursor solution; Mixing sulfur powder and octadecene, heating the solution to 130° C. to 180° C., and exhausting the gas; after exhausting the gas, heating the solution to 150° C. to 180° C. to completely dissolve the sulfur powder, thereby obtaining a sulfur precursor solution; The zinc precursor solution, the selenium precursor solution and the sulfur precursor solution with equal volumes are mixed to obtain the precursor solution, wherein the precursors include a zinc precursor, a selenium precursor and a sulfur precursor.
10. The preparation method according to claim 5, characterized in that The steps of preparing the quantum dot solution include: Mixing cadmium oxide powder, zinc oxide powder, a second surface modifier, n-octyl mercaptan, and liquid paraffin, heating the solution to 150° C. to 170° C. under nitrogen conditions, and exhausting the gas; after exhausting the gas, heating the solution to 260° C. to 300° C. to completely dissolve the cadmium oxide powder and the zinc oxide powder, thereby obtaining a cadmium precursor solution; dissolving sulfur powder in 1-octadecene and stirring to obtain a sulfur precursor solution; The cadmium precursor solution is added to the sulfur precursor solution to react to form cadmium sulfide particles to obtain the quantum dots, and the second surface modifier forms the second surface ligand on the surface of the quantum dots, wherein the reaction temperature is 280° C. to 320° C. and the heating is maintained for 25 to 35 minutes; after the reaction is completed, the solution temperature is lowered to room temperature, and the solution is washed and purified to obtain a quantum dot solution; Wherein, the second surface modifier includes oleic acid.