A quantum dot light-converting agricultural film doped with metal nanoparticles and a preparation method thereof

Abstract

The present invention relates to the technical field of quantum dot light-converting agricultural film, and in particular to a quantum dot light-converting agricultural film doped with metal nanoparticles and a preparation method thereof, the steps comprising preparing quantum dot materials by a one-pot method; preparing metal nanoparticles by a chemical reduction method; doping metal nanoparticles into quantum dot materials and mixing them to obtain a quantum dot colloidal solution doped with metal nanoparticles; mixing the quantum dot colloidal solution with a polymer material and adding them to an extruder, and performing high-temperature melt granulation to obtain a quantum dot light-converting agricultural film by a film blowing machine. The above method dopes metal nanoparticles such as gold and silver on the basis of traditional quantum dot light-converting agricultural films. Due to the plasma resonance effect on the surface of the metal nanoparticles, the performance attenuation of quantum dots in the long-term degradation process can be reduced, and the stability of quantum dots can be improved; at the same time, the electric field can be strengthened, the recombination of electrons and holes in quantum dots can be accelerated, and the luminescence intensity of quantum dots can be enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of quantum dot light-converting agricultural films, and in particular to a quantum dot light-converting agricultural film doped with metal nanoparticles and a preparation method thereof. Background Art

[0002] Facility agriculture is an important technology to ensure agricultural production and has been widely promoted in the north and south of my country. In order to convert and store energy during photosynthesis, artificial lighting methods represented by quantum dot light-converting agricultural films have become one of the main means to ensure facility agricultural production.

[0003] When using quantum dot light-converting agricultural film for supplementary lighting, sunlight is used to excite the quantum dot material. Usually, the quantum dot material with light conversion function is doped into a polymer film to make the light-converting agricultural film. Under sunlight, the ultraviolet light (250nm~400nm), green light (500nm~560nm) and yellow light (580nm~595nm) in the sunlight can be selectively converted into the red light necessary for the photosynthesis of crops, effectively promoting the growth of crops.

[0004] During this process, the quantum dot light-converting agricultural film is exposed to sunlight for a long time, and the performance of the quantum dots inside it will decay to varying degrees, which will seriously affect the performance of the light-converting agricultural film. Therefore, there is an urgent need for an optimization solution for quantum dot light-converting agricultural film that can slow down the performance decay of quantum dots in the light-converting agricultural film during long-term degradation and improve the luminescence intensity and stability of quantum dots in the light-converting agricultural film. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a quantum dot light-converting agricultural film doped with metal nanoparticles and a preparation method thereof.

[0006] The first object of the present invention is to provide a method for preparing a quantum dot light-converting agricultural film doped with metal nanoparticles, comprising the following steps:

[0007] S1. One-pot method for preparing quantum dot materials;

[0008] S2. Preparation of metal nanoparticles by chemical reduction method;

[0009] S3. doping the metal nanoparticles into the quantum dot material and mixing to obtain a quantum dot colloidal solution doped with metal nanoparticles;

[0010] S4. The quantum dot colloidal solution is mixed with a polymer material and then added into an extruder. After high-temperature melt granulation, a metal nanoparticle-doped quantum dot light-converting agricultural film is prepared by a film blowing machine.

[0011] Preferably, in step S1, the quantum dot material is at least one of perovskite quantum dots, II-VI group quantum dots, III-V group quantum dots, and IV-VI group quantum dots.

[0012] Preferably, the quantum dot material is copper indium sulfide quantum dots, and the preparation process is as follows:

[0013] Copper iodide, indium acetate, dodecyl mercaptan, octadecene and oleic acid are mixed and stirred and heated for reaction under inert gas purging; after cooling, an acetone solution is added, and the supernatant is removed by centrifugation to obtain precipitated copper indium sulfur quantum dots.

[0014] Preferably, the copper indium sulfide quantum dots are synthesized with a zinc sulfide shell by hot injection of a zinc source solution, and the preparation process is as follows:

[0015] Toluene solution is added to copper indium sulfide quantum dots to obtain a copper indium sulfide quantum dot solution, zinc stearate, octadecene and tri-n-octylphosphine solution are mixed to obtain a zinc source solution; the copper indium sulfide quantum dot solution, octadecene, dodecyl mercaptan and oleic acid are mixed, stirred and heated under inert gas purging, and the zinc source solution is added to heat for reaction; after cooling, a toluene solution, an acetone solution and an ethanol solution are added, and the supernatant is removed after standing for stratification to obtain copper indium sulfide quantum dots with a zinc sulfide shell.

[0016] Preferably, in step S2, the metal nanoparticles are gold nanoparticles or silver nanoparticles.

[0017] Preferably, the metal nanoparticles are gold nanoparticles, and the preparation process is as follows:

[0018] The chloroauric acid solution was stirred and heated, and a reducing agent sodium citrate solution was added to react. After stopping the heating, the stirring was continued and the solution was cooled to room temperature to obtain a solution of gold nanoparticles.

[0019] Preferably, in step S4, the polymer material is at least one of polyethylene, polypropylene, polyvinyl chloride or polystyrene.

[0020] Preferably, the mixing mass ratio of the quantum dot colloid solution to the polymer material is 1:20 to 1:80.

[0021] The second purpose of the present invention is to provide a quantum dot light-conversion agricultural film doped with metal nanoparticles, which is prepared by a preparation method of a quantum dot light-conversion agricultural film doped with metal nanoparticles. The quantum dot material of the quantum dot light-conversion agricultural film is doped with metal nanoparticles, and the quantum dot material is at least one of perovskite quantum dots, II-VI group quantum dots, III-V group quantum dots, and IV-VI group quantum dots. The metal nanoparticles are gold nanoparticles or silver nanoparticles.

[0022] Preferably, the thickness of the metal nanoparticle-doped quantum dot light-converting agricultural film is 0.5-2 mm.

[0023] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0024] The metal nanoparticle-doped quantum dot light-converting agricultural film prepared by the preparation method provided by the present invention is doped with metal nanoparticles such as gold and silver on the basis of the traditional quantum dot light-converting agricultural film. Due to the plasma resonance effect on the surface of the metal nanoparticles, the performance attenuation of the quantum dots in the light-converting agricultural film during the long-term degradation process can be reduced, and the stability of the quantum dots in the light-converting agricultural film can be effectively improved; at the same time, the plasma resonance effect on the surface of the metal nanoparticles can strengthen the electric field and accelerate the recombination of electrons and holes in the quantum dots, thereby enhancing the luminescence intensity of the quantum dots in the light-converting agricultural film. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flowchart of a method for preparing a quantum dot light-converting agricultural film doped with metal nanoparticles according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the process of preparing a method for a quantum dot light-converting agricultural film doped with metal nanoparticles according to an embodiment of the present invention;

[0027] Figure 3 Schematic diagram of the microstructure of copper indium sulfide quantum dots and gold nanoparticles provided according to an embodiment of the present invention; in the figure, A represents the prepared copper indium sulfide quantum dots, and B represents the prepared gold nanoparticles;

[0028] Figure 4 This is a SEM scanning electron microscope image of copper indium sulfide quantum dots provided according to an embodiment of the present invention; in the figure, A represents 200nm, and B represents 500nm;

[0029] Figure 5 is a SEM scanning electron microscope image of gold nanoparticles provided according to an embodiment of the present invention;

[0030] Figure 6 It is an absorption spectrum and an emission spectrum diagram of a quantum dot light-converting agricultural film doped with metal nanoparticles provided in an embodiment of the present invention;

[0031] Figure 7 This is a luminescence intensity spectrum of light-converting agricultural film based on copper indium sulfide quantum dots doped in different proportions provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0034] Example 1

[0035] The present invention provides a method for preparing a quantum dot light-converting agricultural film doped with metal nanoparticles. The preparation process is as follows: Figure 1 , Figure 2 As shown, the following steps are included:

[0036] S1. One-pot method was used to prepare quantum dot materials.

[0037] In this embodiment, copper indium sulfide (CuInS2) quantum dots are prepared by a one-pot method.

[0038] First, prepare 0.05mmol copper iodide (CuI), 0.2mmol indium acetate (In(C2H3O2)3), 10mol dodecyl mercaptan (DDT), 8mL octadecene (ODE) and 0.4mmol oleic acid (OA) as raw materials for preparing copper indium sulfur quantum dots, and add the above materials into a 50mL three-necked flask in sequence. Since the synthesis of copper indium sulfur quantum dots must be carried out in an oxygen-free environment, the above mixed solution is placed in an oil bath, heated to 120°C, and stirred with a magnetic stirrer for 30 minutes to mix it evenly. At the same time, it is purged with nitrogen for 50 minutes to remove oxygen. It can be observed that the mixed solution at this time is a light yellow clear solution.

[0039] The solution was then heated to 210°C, at which time copper indium sulfur quantum dots gradually formed in the solution. The solution was heated continuously at 210°C for 1 hour, and it was observed that the color of the solution gradually darkened, gradually changing from a light yellow solution to a red solution, to obtain a dark brown copper indium sulfur quantum dot solution.

[0040] After the solution was cooled to 50°C, acetone solution was added to the flask. The ratio of copper indium sulfur quantum dot solution to acetone solution was 1:3. After centrifugation at 6000r / min for 2 minutes, the supernatant was removed to obtain precipitated copper indium sulfur quantum dots. Toluene solution was then added to the container to finally obtain a CuInS2 quantum dot solution dissolved in toluene.

[0041] In order to improve the stability and luminescence intensity of copper indium sulfide quantum dots, zinc sulfide (ZnS) with a lattice similar to that of copper indium sulfide quantum dots and a matching energy level structure arrangement is selected as the shell. In this embodiment, the ZnS shell of copper indium sulfide quantum dots is synthesized by hot injection of zinc source solution.

[0042] First, 632 mg (1 mmol) of zinc stearate, 4 mL of octadecene (ODE) and 1 mL of TOP solution were fully mixed as a zinc source solution; the CuInS2 quantum dot solution dissolved in toluene prepared in the above process, 8 mL of octadecene (ODE), 2.4 mL of dodecyl mercaptan (DDT) and 0.12 mL of oleic acid (OA) were selected, and the above materials were added sequentially into a 50 ml three-necked flask. In order to remove toluene in the solution, the mixed solution was purged with argon for 30 minutes to exclude oxygen, and heated to 110°C at the same time, and stirred with a magnetic stirrer for 30 minutes to mix it evenly, and then the solution was heated to 120°C and kept at a constant temperature.

[0043] Inject the previously prepared zinc source solution into the flask, heat the mixed solution to 230°C, and continue the reaction for 1 hour. After the reaction is completed, remove the heating device, and after the solution temperature drops below 210°C, use a cold water bath to quickly cool it to 50°C, then add 10mL of 50°C toluene solution, 10mL of acetone solution and 5mL of ethanol solution, and let it stand for 5 hours to allow the solution to separate into layers. Then remove the supernatant and add a small amount of toluene to dissolve the precipitated CuInS2 quantum dots.

[0044] S2. Prepare metal nanoparticles by chemical reduction method.

[0045] In this embodiment, gold nanoparticles were prepared by chemical reduction method.

[0046] The preparation concentration is 2.44×10 -3 mol / L chloroauric acid (HAuCl4·4H2O) solution was used as the reaction material, and the concentration was 3.43×10 -2 mol / L sodium citrate (Na3C6H5O7·2H2O) solution was used as a reducing agent. 20 mL of HAuCl4·4H2O solution was added to a 50 mL round-bottom flask, and then a magnetic bar was placed in the flask, and a spherical condenser was connected. The flask was placed on a digital speed-controlled constant temperature magnetic stirrer and stirred while heating the flask. The stirring speed was set to 600 r / min, and the heating temperature of the flask was 75 °C.

[0047] While stirring at high speed, use a pipette to transfer 2 mL of the prepared Na3C6H5O7·2H2O solution and quickly add it to the HAuCl4·4H2O solution. It can be observed that the color of the solution gradually changes from light yellow to orange-red. At this time, the timing starts to keep the color of the liquid constant and continue to heat. After reflux for 10 minutes under intense stirring, stop heating and remove the heat source, then continue stirring for 15 minutes and stop stirring. The solution is cooled to room temperature. The orange-red liquid finally obtained is a nanogold solution. The particle size of the gold nanoparticles prepared in the solution can be observed by transmission scanning electron microscopy to be 18 nm. The microstructures of copper indium sulfur quantum dots and gold nanoparticles are as follows: Figure 3 , Figure 4 and Figure 5 shown. Figure 3 The diagram shows the positional relationship between the copper indium sulfide quantum dots and the gold nanoparticles after doping; Figure 4 Shown is the microscopic characterization of copper indium sulfide quantum dots under a scanning electron microscope; Figure 5 Shown is the microscopic characterization of gold nanoparticles under a scanning electron microscope.

[0048] During the preparation of gold nanoparticles, Na3C6H5O7·2H2O solution needs to be quickly added to HAuCl4·4H2O solution. At this time, the color of the solution gradually changes from light yellow to orange-red. When the size of the gold nanoparticles is less than 20 nm, the solution appears orange-red; when the size is between 20 and 70 nm, the solution appears red; when the size is between 70 and 90 nm, the solution appears wine red; when the size is greater than 90 nm, the solution appears purple; and when the small-sized gold nanoparticles are severely aggregated, the solution appears blue.

[0049] According to the relationship between the size of the nanoparticles and the color of the solution, if the Na3C6H5O7·2H2O solution is not added quickly enough during the experiment, the gold nanoparticle solution can be observed to turn light blue first and then slowly turn red. This is mainly because when the Na3C6H5O7·2H2O solution is added too slowly, the gold nanoparticles are gradually reduced, and the earliest generated gold element will continue to grow as a crystal nucleus, resulting in a larger size of the obtained gold nanoparticles, so the observed solution appears blue; with the continued addition of the Na3C6H5O7·2H2O solution, the number of small-sized gold nanoparticles increases, and the blue in the solution is gradually covered by the red; although the final gold nanoparticle solution still appears red, the slow addition of the Na3C6H5O7·2H2O solution will result in uneven size of the obtained gold nanoparticles. Therefore, during the experiment, the Na3C6H5O7·2H2O solution should be quickly added to the HAuCl4·4H2O solution to obtain a gold nanoparticle solution with uniform size.

[0050] S3. doping the metal nanoparticles into the quantum dot material and mixing to obtain a quantum dot colloidal solution doped with metal nanoparticles;

[0051] S4. The quantum dot colloidal solution is mixed with the polymer material and then added into an extruder. After high-temperature melting and granulation, the quantum dot light-converting agricultural film is prepared by a film blowing machine.

[0052] Based on the above preparation, gold nanoparticles are doped into the copper indium sulfur quantum dot colloidal solution and fully mixed, and the mixed solution and polyethylene with a melt index of 25g / 10min are mixed evenly in a ratio of 1:50, added to the extruder feed funnel, and the temperature is heated to 160°C. The mixed material is extruded through a twin-screw extruder at a speed of 500r / min and then cooled and granulated to finally obtain the masterbatch of quantum dot light-converting agricultural film. The masterbatch of the quantum dot light-converting agricultural film prepared above is added to a mixed solution of vinyl bisstearamide, polyethylene, and anti-ultraviolet agent benzophenone, wherein the mass ratio of the masterbatch of the quantum dot light-converting agricultural film to vinyl bisstearamide is 2:1, the mass ratio to the polyethylene material is 1:10, and the mass ratio to the anti-ultraviolet agent benzophenone is 10:1. After the above materials are fully mixed, they are added to a mixer and stirred at a stirring speed of 1500r / min for 30 minutes. After stirring evenly, they are added to the material trough of a film blowing machine and wait for film blowing; the die head temperature of the film blowing machine is 160°C, and the melting temperature is 180°C. Finally, a quantum dot light-converting agricultural film doped with metal nanoparticles is obtained. The absorption spectrum and emission spectrum of the quantum dot light-converting agricultural film doped with metal nanoparticles are shown in the following figures Figure 6 shown.

[0053] Example 2

[0054] The embodiment of the present invention provides a method for preparing a quantum dot light-converting agricultural film doped with metal nanoparticles, wherein the preparation steps are different from those in Example 1 in that the molar ratio of copper iodide (CuI) to indium acetate (In(C2H3O2)3) in step S1 is changed to 1:2, that is, the added amounts are 0.1 mmol and 0.2 mmol, respectively.

[0055] The luminescence intensity spectra of the metal nanoparticle-doped quantum dot light-converting agricultural films prepared in Example 1 and Example 2 are as follows: Figure 7 As shown; it can be seen from the figure that when the ratio of copper to indium is 1:4, the luminous intensity of the light-converting agricultural film is higher.

[0056] Comparative Example 1

[0057] The preparation process of the comparative light-converting agricultural film is as follows:

[0058] The CuInS2 quantum dot material prepared in step S1 and the polyethylene material with a melt index of 25g / 10min are mixed in a ratio of 1:50, added to the extruder feed funnel, and the temperature is heated to 160°C. The mixed material is extruded by a twin-screw extruder at a speed of 500r / min, and then cooled and granulated to finally obtain the masterbatch of copper indium sulfur quantum dot light-converting agricultural film; the masterbatch of copper indium sulfur quantum dot light-converting agricultural film prepared above is added to a mixed solution of vinyl bisstearamide, polyethylene material, and anti-ultraviolet agent benzophenone The mass ratio of the masterbatch of the copper indium sulfide quantum dot light-converting agricultural film to vinyl bisstearamide is 2:1, the mass ratio to the polyethylene material is 1:10, and the mass ratio to the anti-ultraviolet agent benzophenone is 10:1. After the above materials are fully mixed, they are added to a mixer and stirred at a stirring speed of 1500r / min for 30 minutes. After stirring evenly, they are added to the material trough of a film blowing machine and wait for film blowing; the die head temperature of the film blowing machine is 160°C, and the melting temperature is 180°C, and finally the CuInS2 quantum dot light-converting agricultural film is obtained.

[0059] The comparative example CuInS2 quantum dot light-conversion agricultural film and the metal nanoparticle-doped quantum dot light-conversion agricultural film of Example 1 were experimentally compared under the same lighting environment. It can be observed that the luminescence intensity of the metal nanoparticle-doped quantum dot light-conversion agricultural film is significantly stronger than that of the CuInS2 quantum dot light-conversion agricultural film, and the performance attenuation of the metal nanoparticle-doped quantum dot light-conversion agricultural film under long-term lighting conditions is also better than that of the CuInS2 quantum dot light-conversion agricultural film. It can be seen that compared with the prior art, the present invention can effectively improve the stability and luminescence intensity of quantum dots in the light-conversion agricultural film by doping metal nanoparticles in the quantum dot light-conversion agricultural film.

[0060] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0061] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a quantum dot light-converting agricultural film doped with metal nanoparticles, characterized in that: The steps include: S1. Copper indium sulfide quantum dots were prepared by one-pot method, and quantum dot materials with zinc sulfide shell were synthesized by hot injection of zinc source solution; S2. Preparing metal nanoparticles by chemical reduction; the metal nanoparticles are gold nanoparticles or silver nanoparticles; S3. doping the metal nanoparticles into the quantum dot material and mixing to obtain a quantum dot colloidal solution doped with metal nanoparticles; S4. The quantum dot colloidal solution is mixed with a polymer material and then added into an extruder. After high-temperature melt granulation, a metal nanoparticle-doped quantum dot light-converting agricultural film is prepared by a film blowing machine.

2. The method for preparing the metal nanoparticle-doped quantum dot light-converting agricultural film according to claim 1, characterized in that: The preparation process of copper indium sulfide quantum dots is as follows: Copper iodide, indium acetate, dodecyl mercaptan, octadecene and oleic acid are mixed and stirred and heated for reaction under inert gas purging; after cooling, an acetone solution is added, and the supernatant is removed by centrifugation to obtain precipitated copper indium sulfur quantum dots.

3. The method for preparing the metal nanoparticle-doped quantum dot light-converting agricultural film according to claim 2, characterized in that: The preparation process of copper indium sulfide quantum dots with zinc sulfide shells synthesized by hot injection of zinc source solution is as follows: Toluene solution is added to copper indium sulfide quantum dots to obtain a copper indium sulfide quantum dot solution, zinc stearate, octadecene and tri-n-octylphosphine solution are mixed to obtain a zinc source solution; the copper indium sulfide quantum dot solution, octadecene, dodecyl mercaptan and oleic acid are mixed, stirred and heated under inert gas purging, and the zinc source solution is added to heat for reaction; after cooling, a toluene solution, an acetone solution and an ethanol solution are added, and the supernatant is removed after standing for stratification to obtain copper indium sulfide quantum dots with a zinc sulfide shell.

4. The method for preparing the metal nanoparticle-doped quantum dot light-converting agricultural film according to claim 3, characterized in that: The metal nanoparticles are gold nanoparticles, and the preparation process is as follows: The chloroauric acid solution was stirred and heated, and a reducing agent sodium citrate solution was added to react. After stopping the heating, the stirring was continued and the solution was cooled to room temperature to obtain a solution of gold nanoparticles.

5. The method for preparing the metal nanoparticle-doped quantum dot light-converting agricultural film according to claim 4, characterized in that: In the step S4, the polymer material is at least one of polyethylene, polypropylene, polyvinyl chloride or polystyrene.

6. The method for preparing the metal nanoparticle-doped quantum dot light-converting agricultural film according to claim 5, characterized in that: The mixing mass ratio of the quantum dot colloid solution to the polymer material is 1:20 to 1:

80.

7. A metal nanoparticle-doped quantum dot light-conversion agricultural film, prepared by the preparation method of the metal nanoparticle-doped quantum dot light-conversion agricultural film according to any one of claims 1 to 6.

8. The metal nanoparticle-doped quantum dot light-converting agricultural film according to claim 7, characterized in that: The thickness of the metal nanoparticle-doped quantum dot light-converting agricultural film is 0.5-2 mm.

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