A quantum dot with high ultraviolet absorption, its preparation method and application

Abstract

This invention belongs to the field of quantum dot preparation technology, specifically relating to a quantum dot with high ultraviolet absorption, its preparation method, and its applications. The preparation method includes: 1) preparing a precursor solution for the reaction; 2) synthesizing a quantum dot core; 3) repairing the quantum dot core using a ZnX solution; and 4) encapsulating the repaired quantum dot core with the precursor solution to form a quantum dot with a quantum dot core-ZnX repair layer-quantum dot shell structure, thus obtaining the quantum dot with high ultraviolet absorption. Using the method of this invention to prepare quantum dots broadens the ultraviolet absorption range, improves the ultraviolet absorption capacity, enhances the efficiency of the quantum dots, and maintains high stability.

Description

Technical Field

[0001] This invention belongs to the field of quantum dot preparation technology, specifically, it relates to a quantum dot with high ultraviolet absorption, its preparation method and application. Background Technology

[0002] Quantum dots are semiconductor nanocrystals with dimensions of a few nanometers, exhibiting significant quantum size effects and unique optical properties. When stimulated by light or electricity, quantum dots emit light of a specific wavelength, the wavelength of which is determined by the constituent materials, size, and shape of the quantum dots. Compared to organic materials, quantum dots offer superior color purity and thermal stability. These properties have attracted widespread attention due to their potential applications in lighting, displays, solar energy, and biomarking.

[0003] Currently, the synthesis of highly efficient and stable quantum dots mostly involves coating the surface of the luminescent core with organic or inorganic layers, such as CdSe / ZnS core-shell quantum dots. To achieve optimal applications, it's necessary to maximize the stability of the quantum dots, which requires increasing the shell thickness. However, due to the lattice parameter mismatch between the core and shell, surface defects increase with the number of shells, leading to a gradual decrease in luminescence efficiency. Multiple shell coatings are employed, such as CdSe / CdS / ZnS, CdSe / CdSe / ZnS, and CdSe / CdS / CdZnS.

[0004] Chinese Patent Application No. 201610027909.5 discloses a method for preparing CdSe / CdS / ZnS quantum dots, characterized by the following steps: ① preparing a Cd precursor by dissolving 5 mmol of 99.9% CdO in a mixture of 25 mmol of 99% LA and 8 mmol of 95% HDA in argon gas at a certain temperature; ② preparing a Se precursor by dissolving 5 mmol of Se powder in 6.5 mmol of 90% TOP; ③ injecting the product obtained in step ② into the preparation method of CdSe / CdS / ZnS quantum dots. Step ① involves forming CdSe nanocrystals in the product obtained, and then cooling the temperature below 280℃. The product is then washed with hot methanol. Step ④ involves alternately injecting Cd(CH2COO)2 and Na2S(9H2O) into the CdSe nanocrystals, and refluxing the mixture at a temperature not exceeding 40℃ to prepare CdSe / CdS nanocrystals. Step ⑤ involves alternately injecting Zn(CH2COO)2 and Na2S(9H2O) into the product obtained in step ④, and refluxing the mixture at a temperature not exceeding 40℃ to prepare CdSe / CdS / ZnS quantum dots. This process increases the efficiency and stability of quantum dots to some extent, but there is still room for improvement in efficiency and stability. Furthermore, the numerous and complex synthesis steps hinder large-scale production and significantly limit the application of quantum dots.

[0005] CN107090291A discloses a method for preparing CdSe / CdZnSeS / ZnS core-shell quantum dots that is simple to synthesize, has a short synthesis time, high quantum efficiency, and high stability. The method comprises the following steps: (1) mixing and stirring a zinc source, a cadmium source, an organic solvent, and an organic ligand until homogeneous, then heating to 260-320℃, with a protective gas introduced throughout the reaction process; (2) rapidly injecting a homogeneously mixed selenium precursor and a sulfur precursor while stirring; (3) starting the timing after the precursor in step (2) has been completely injected, injecting the sulfur precursor again within 0-30 seconds; (4) reacting at 260-300℃ for 1-60 minutes. The beneficial effects of this invention are: using CdZnSeS as a medium to connect the core CdSe and the shell CdS, the quantum dot core and shell exhibit high lattice matching, very high photostability and thermal stability, and a quantum yield exceeding 80%. The synthesis steps of this invention are simple and easy to operate, facilitating large-scale production.

[0006] However, it was found in use that the quantum dots prepared by the above method have a limited ultraviolet absorption range, and it is necessary to broaden the ultraviolet absorption range and improve the ultraviolet absorption capacity. Summary of the Invention

[0007] The purpose of this invention is to provide a quantum dot with high ultraviolet absorption, its preparation method, and its applications. The method of this invention broadens the ultraviolet absorption range, improves the ultraviolet absorption capacity, and simultaneously increases the efficiency of the quantum dot.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing quantum dots with high ultraviolet absorption, wherein the preparation method includes the following steps:

[0010] 1) Prepare the precursor solution required for the reaction;

[0011] 2) Preparation of quantum dot cores;

[0012] 3) Repairing quantum dot cores using ZnX solution;

[0013] 4) The repaired quantum dot core is coated with a precursor solution to form a quantum dot with a quantum dot core-ZnX repair layer-quantum dot shell structure, thus obtaining the quantum dot with high ultraviolet absorption.

[0014] In this invention, the quantum dot core is composed of one of ZnSe, CdS, ZnS, CdZnS, CdZnSe, ZnSeS, or CdZnSeS;

[0015] In this invention, ZnX is ZnF2, ZnCl2, ZnBr2, ZnI2, Zn(SH)2, Zn(CN)2, or C. 32 H 16 One of N8Zn;

[0016] In this invention, the quantum dot shell is composed of any one or more of ZnS, ZnSe, CdZnSe, CdZnS, ZnSeS, or CdZnSeS.

[0017] This invention utilizes ZnX (where X is a carboxyl group, thiol, or halogen element, etc.) to repair quantum dot nuclei. These X-type ligands (such as X being a carboxyl group, thiol, or halogen element, etc.) exhibit strong affinity, resulting in strong bonds with the quantum dot nucleus surface. Treatment of the quantum dot nucleus with X-type ligands alters the band gap structure, creating donor impurity energy levels within the band gap. This change in electronic structure reduces the band gap and simultaneously generates new energy levels, providing an intermediate band for electronic transitions. Therefore, electrons in the valence band can be excited to intermediate states with relatively low energy, and then transition from these intermediate states to the conduction band, expanding the delocalization range of photoexcitons in the quantum dot, thereby broadening the ultraviolet absorption range and improving ultraviolet absorption capacity. Furthermore, halogens or thiols can also serve as intermediate ligands to passivate cation defects on the quantum dot nucleus surface, improving the efficiency and stability of the quantum dot.

[0018] Further, in step 1), the method for preparing the anion precursor solution is as follows: under an argon atmosphere, an anion source is added to an organic solvent or a long-chain alkylphosphine until the solid is completely dissolved to obtain the anion precursor solution;

[0019] The method for preparing the cation precursor solution is as follows: under an argon atmosphere, the cation source is mixed with an organic solvent until the solid is completely dissolved to obtain the cation precursor solution.

[0020] Further, in step 1), the anionic precursor is one or a combination of two of the sulfur precursor and the selenium precursor; the cationic precursor is one or a combination of two of the zinc precursor and the cadmium precursor.

[0021] Furthermore, the molar concentration of the sulfur precursor solution is 0.2-2 mmol / ml, and the synthesis method is as follows: under an argon atmosphere, the sulfur source is added to an organic solvent or a long-chain alkylphosphine, heated, and kept at a constant temperature to obtain the sulfur precursor solution.

[0022] Furthermore, the molar concentration of the selenium precursor solution is 0.1-2 mmol / ml. The synthesis method is as follows: under an argon atmosphere, the selenium source is added to an organic solvent or a long-chain alkylphosphine, heated, and kept at a constant temperature until the solid is completely dissolved to obtain the selenium precursor solution.

[0023] Furthermore, the molar concentration of the zinc precursor solution is 0.5-50 mmol / ml. The synthesis method is as follows: under an argon atmosphere, the zinc source is mixed with an organic solvent, stirred, and heated to 250-280℃ until the solid is completely dissolved to obtain the zinc precursor solution.

[0024] Furthermore, the molar concentration of the cadmium precursor solution is 0.5-50 mmol / ml. The synthesis method is as follows: under an argon atmosphere, the cadmium source is mixed with an organic solvent, stirred, and heated to 250-280℃ until the solid is completely dissolved to obtain the cadmium precursor solution.

[0025] Furthermore, the anion source is a sulfur source or a selenium source; the cation source is a zinc source or a cadmium source.

[0026] Furthermore, the sulfur source is one of sulfur powder, dodecyl mercaptan, and octyl mercaptan.

[0027] Furthermore, the selenium source is selenium powder.

[0028] Furthermore, the zinc source is one of zinc oxide, zinc acetate, and zinc stearate.

[0029] Furthermore, the cadmium source is one of cadmium oxide, cadmium acetate, and cadmium stearate.

[0030] Further, the organic solvent includes a coordination solvent and / or a non-coordination solvent. The coordination solvent is a saturated or unsaturated fatty acid with ≥5 carbon atoms and / or a saturated or unsaturated amine compound with ≥6 carbon atoms, preferably oleic acid. The non-coordination solvent is one or any combination of two or more of alkanes, alkenes, ethers or aromatic compounds with ≥10 and ≤22 carbon atoms, preferably octadecene.

[0031] Furthermore, the long-chain alkylphosphine is tributylphosphine or trioctylphosphine.

[0032] Further, step 2) specifically involves: mixing the cation source, coordinating solvent, and non-coordinating solvent under an argon atmosphere, heating to 280-350℃, rapidly injecting the anion precursor solution, reacting for 30s-15min, cooling to room temperature, centrifuging the resulting liquid, drying it, and obtaining quantum dot nuclei.

[0033] Furthermore, the anionic precursor is one or both of sulfur precursor and selenium precursor; the cation source is one or both of zinc source and cadmium source.

[0034] Furthermore, the molar ratio of the cation source to the coordination solvent is 1:2 to 1:6; the volume ratio of the coordination solvent to the non-coordination solvent is 2:1 to 1:20.

[0035] Furthermore, the molar ratio of the cation source to the anion precursor solution is 1:30-5:1.

[0036] Furthermore, the injection is completed in 1-10 seconds.

[0037] Further, step 3) specifically involves: dissolving the quantum dot nucleus in a nonpolar organic solvent, adding a cationic precursor solution, a ZnX solution, and a noncoordinate solvent to the resulting solution, heating to 290-310℃ under nitrogen protection, and holding at that temperature for 0.5-1.5h to obtain the repaired quantum dot nucleus.

[0038] Furthermore, the molar ratio of the quantum dot core solution, the cation precursor solution, and the ZnX solution is 1:2:1 to 1:20:5.

[0039] Furthermore, the nonpolar organic solvent is one of hexane, octane, toluene, or chloroform.

[0040] In this invention, the ZnX solution is prepared by the following method: ZnX is mixed with an organic solvent under an argon atmosphere, heated to 280°C and held for 20 minutes, then cooled to 100°C and held for later use.

[0041] In this invention, the molar concentration of the ZnX solution is 2-10 mmol / ml.

[0042] Furthermore, the molar ratio of ZnX to the organic solvent is 1:2 to 1:5.

[0043] Further, step 4) specifically involves: adding an anionic precursor solution dropwise to the quantum dot core solution that has been repaired in step 3; after the addition is complete, keeping it warm for 0.5-1.5 hours; after cooling to room temperature, centrifuging the resulting liquid and drying it to obtain the quantum dots with high ultraviolet absorption.

[0044] Further, in step 4), the molar ratio of the anionic precursor solution to the cationic precursor solution in step 3) is 5:1 to 1:5.

[0045] The dripping rate is 0.8-1.2 ml / h.

[0046] The present invention also provides a quantum dot, wherein the quantum dot is prepared by the above-described preparation method.

[0047] The quantum dots provided by this invention broaden the range of ultraviolet absorption, improve the ability to absorb ultraviolet light, and also improve the efficiency of quantum dots.

[0048] The present invention also provides the application of the quantum dots in the fabrication of photovoltaic modules.

[0049] Photovoltaic modules prepared using quantum dots of the present invention can absorb more ultraviolet light and convert it into visible light that the photovoltaic module can utilize. This not only improves the photoelectric conversion efficiency of the module but also extends its service life.

[0050] Compared with the prior art, the present invention has the following advantages:

[0051] The method of this invention for preparing quantum dots broadens the range of ultraviolet absorption, improves the ability to absorb ultraviolet light, and also increases the efficiency of quantum dots. Attached Figure Description

[0052] Figure 1 The following are the ultraviolet-visible absorption spectra of quantum dots in Example 1 and Comparative Example 1;

[0053] Figure 2 The quantum dot fluorescence intensity spectra of Example 1 and Comparative Example 1 are shown. Detailed Implementation

[0054] The following are specific embodiments of the present invention. These embodiments are intended to further describe the present invention and are not intended to limit the present invention.

[0055] Example 1: Preparation of CdZnS-ZnCl2 / ZnS

[0056] 1) Preparation of the precursor solution required for the reaction

[0057] ① Preparation of the first sulfur precursor S-ODE solution: Under argon atmosphere, 5 mmol of S was added to 10 ml of octadecene (ODE) solution, heated to 120 °C and held for 60 min until the solid was completely dissolved, to obtain an S-ODE solution with a concentration of 0.5 mmol / ml, which was then kept at 100 °C for later use.

[0058] ② Preparation of the second sulfur precursor TOPS solution: Under argon atmosphere, 5 mmol of S was added to 10 ml of trioctylphosphine (TOP) solution and stirred until the solid was completely dissolved to obtain a TOPS solution with a concentration of 0.5 mmol / ml, which was then set aside for use.

[0059] ③ Preparation of zinc precursor solution: Under argon atmosphere, add 20 mmol of zinc acetate, 20 ml of oleic acid and 20 ml of octadecene (ODE) to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear, and the zinc precursor solution is obtained. Cool down to 100℃ and keep warm for later use.

[0060] 2) Preparation of quantum dot cores

[0061] 1 mmol of cadmium oxide, 10 mmol of zinc acetate, and 10 ml of oleic acid were added to a four-necked flask. The mixture was heated to 120 °C and held at this temperature for 1 hour under a nitrogen atmosphere. Then, 20 ml of octadecene was added, and the temperature was raised to 300 °C. 3 ml of the prepared S-ODE solution was then rapidly injected and held at this temperature for 12 minutes, followed by cooling to room temperature. The liquid was centrifuged three times and dried to obtain quantum dot cores.

[0062] 3) Repairing quantum dot cores using ZnCl2 solution

[0063] Preparation of ZnCl2 solution: Under argon atmosphere, add 10 mmol ZnCl2, 20 ml oleic acid and 20 ml octadecene (ODE) to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear, then cool to 100℃ and keep warm for later use.

[0064] The quantum dot nuclei were dissolved in toluene to form a solution with a concentration of 0.5 mmol / ml. 5 mmol of zinc precursor solution, 15 mmol of ZnCl2 solution and 50 ml of octadecene were added to the resulting solution. The solution was heated to 300 °C under argon protection and kept at this temperature for 1 h to obtain the repaired quantum dot nuclei.

[0065] 4) Coating the repaired quantum dot cores with a precursor solution.

[0066] Add 10 ml of TOPS solution dropwise to the repaired quantum dot core solution at a rate of 1 ml / h. After the addition is complete, keep the solution at this temperature for 1 hour, then allow it to cool to room temperature. Centrifuge the liquid three times and dry it to obtain the CdZnS-ZnCl2 / ZnS quantum dots with high UV absorption.

[0067] Example 2: Preparation of CdZnSeS-ZnBr2 / ZnS

[0068] 1) Preparation of the precursor solution required for the reaction

[0069] ① Preparation of the sulfur precursor TOPS solution: Under argon atmosphere, 5 mmol of sulfur powder was added to 10 ml of trioctylphosphine (TOP) solution and stirred until the solid was completely dissolved to obtain a TOPS solution with a concentration of 0.5 mmol / ml, which was then set aside for use.

[0070] ② Preparation of selenium precursor TOPSe: Under argon atmosphere, 2 mmol of selenium powder was added to 10 ml of trioctylphosphine (TOP) solution and stirred until the solid was completely dissolved to obtain a TOPSe solution with a concentration of 0.2 mmol / ml, which was then set aside for use.

[0071] ③ Preparation of zinc precursor solution: Under argon atmosphere, add 20 mmol of zinc acetate, 20 ml of oleic acid and 20 ml of octadecene (ODE) to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear, and the zinc precursor solution is obtained. Cool down to 100℃ and keep warm for later use.

[0072] 2) Preparation of quantum dot cores

[0073] 1 mmol of cadmium oxide, 20 mmol of zinc oxide, and 20 ml of oleic acid were added to a four-necked flask. The mixture was heated to 120 °C and held at this temperature for 1 hour under a nitrogen atmosphere. Then, 40 ml of octadecene was added, and the temperature was raised to 310 °C. 6 ml of TOPS solution and 10 ml of TOPSe solution were rapidly injected, and the mixture was held at this temperature for 10 minutes before cooling to room temperature. The liquid was centrifuged three times and dried to obtain quantum dot cores.

[0074] 3) Repairing quantum dot cores using ZnBr2 solution

[0075] Preparation of ZnBr2 solution: Under argon atmosphere, add 15 mmol ZnBr2, 30 ml oleic acid and 30 ml octadecene (ODE) to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear, then cool to 100℃ and keep warm for later use.

[0076] The quantum dot nuclei were dissolved in toluene to form a solution with a concentration of 0.5 mmol / ml. 10 mmol zinc precursor solution, 15 mmol ZnBr2 solution and 30 ml octadecene were added to the resulting solution. The solution was heated to 310 °C under argon protection and kept at this temperature for 1 h to obtain the repaired quantum dot nuclei.

[0077] 4) Coating the repaired quantum dot cores with a precursor solution.

[0078] 16 ml of TOPS solution was added dropwise to the repaired quantum dot core solution at a rate of 0.8 ml / h. After the addition was complete, the solution was kept at this temperature for 1 hour and then cooled to room temperature. The liquid was centrifuged three times and dried to obtain the CdZnSeS-ZnBr2 / ZnS quantum dots with high UV absorption.

[0079] Example 3: Preparation of CdZnSe-Zn(SH)2 / CdZnS

[0080] 1) Preparation of the precursor solution required for the reaction

[0081] ① Preparation of TOPSe solution, a selenium precursor: Under argon atmosphere, 5 mmol of selenium powder was added to 50 ml of trioctylphosphine (TOP) solution and stirred until the solid was completely dissolved to obtain a TOPSe solution with a concentration of 0.1 mmol / ml, which was then set aside for use.

[0082] ② Preparation of the sulfur precursor TOPS solution: Under argon atmosphere, 5 mmol of sulfur powder was added to 10 ml of trioctylphosphine (TOP) solution and stirred until the solid was completely dissolved to obtain a TOPS solution with a concentration of 0.5 mmol / ml, which was then set aside for use.

[0083] ③ Preparation of zinc precursor solution: Under argon atmosphere, add 20 mmol of zinc acetate, 20 ml of oleic acid and 20 ml of octadecene (ODE) to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear, and the zinc precursor solution is obtained. Cool down to 100℃ and keep warm for later use.

[0084] ④ Preparation of cadmium precursor solution: Under argon atmosphere, add 20 mmol of cadmium oxide, 20 ml of oleic acid and 20 ml of octadecene (ODE) to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear, and the cadmium precursor solution is obtained. Cool down to 100℃ and keep warm for later use.

[0085] 2) Preparation of quantum dot cores

[0086] 1 mmol of cadmium oxide, 10 mmol of zinc acetate, and 15 ml of oleic acid were added to a four-necked flask. The mixture was heated to 120 °C and held at this temperature for 1 hour under a nitrogen atmosphere. Then, 30 ml of octadecene was added, and the temperature was raised to 310 °C. 30 ml of TOPSe solution was then rapidly injected, and the mixture was held at this temperature for 10 minutes before cooling to room temperature. The liquid was centrifuged three times and dried to obtain quantum dot cores.

[0087] 3) Repairing quantum dot cores using Zn(SH)2 solution

[0088] Preparation of Zn(SH)2 solution: Under argon atmosphere, add 10 mmol Zn(SH)2, 30 ml oleic acid and 30 ml octadecene (ODE) to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear, then cool to 100℃ and keep warm for later use.

[0089] The quantum dot nuclei were dissolved in toluene to form a solution with a concentration of 0.5 mmol / ml. 20 mmol zinc precursor solution, 10 mmol cadmium precursor solution, 15 mmol Zn(SH)2 solution and 40 ml octadecene were added to the resulting solution. The solution was heated to 310 °C under argon protection and kept at this temperature for 1 h to obtain the repaired quantum dot nuclei.

[0090] 4) Coating the repaired quantum dot cores with a precursor solution.

[0091] 16 ml of TOPS solution was added dropwise to the repaired quantum dot core solution at a rate of 0.8 ml / h. After the addition was complete, the solution was kept at this temperature for 1 hour and then cooled to room temperature. The liquid was centrifuged three times and dried to obtain the CdZnSe-Zn(SH)2 / CdZnS quantum dots with high UV absorption.

[0092] Comparative Example 1: Preparation of CdZnS / ZnS

[0093] This comparative example refers to Example 1, except that the quantum dot cores after centrifugation were not repaired using ZnX solution. Specifically:

[0094] 1) Preparation of the precursor solution required for the reaction

[0095] ① Preparation of the first sulfur precursor S-ODE solution: Under argon atmosphere, 5 mmol of S was added to 10 ml of octadecene (ODE) solution, heated to 120 °C and held for 60 min until the solid was completely dissolved, to obtain an S-ODE solution with a concentration of 0.5 mmol / ml, which was then kept at 100 °C for later use.

[0096] ② Preparation of the second sulfur precursor TOPS solution: Under argon atmosphere, 5 mmol of S was added to 10 ml of trioctylphosphine (TOP) solution and stirred until the solid was completely dissolved to obtain a TOPS solution with a concentration of 0.5 mmol / ml, which was then set aside for use.

[0097] ③ Preparation of zinc precursor solution: Under argon atmosphere, add 20 mmol of zinc acetate, 20 ml of oleic acid and 20 ml of octadecene (ODE) to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear, and the zinc precursor solution is obtained. Cool down to 100℃ and keep warm for later use.

[0098] 2) Preparation of quantum dot cores

[0099] 1 mmol of cadmium oxide, 10 mmol of zinc acetate, and 10 ml of oleic acid were added to a four-necked flask. The mixture was heated to 120 °C and held at this temperature for 1 hour under a nitrogen atmosphere. Then, 20 ml of octadecene was added, and the temperature was raised to 300 °C. 3 ml of the prepared S-ODE solution was then rapidly injected and held at this temperature for 12 minutes, followed by cooling to room temperature. The liquid was centrifuged three times and dried to obtain quantum dot cores.

[0100] 3) Coating quantum dot cores with precursor solutions

[0101] The quantum dot nuclei were dissolved in toluene to a concentration of 0.5 mmol / mL. 5 mmol of zinc precursor solution and 50 mL of octadecene were added to the resulting solution. The mixture was heated to 300 °C under argon protection, and 10 mL of TOPS solution was added dropwise at a rate of 1 mL / h. After the addition was complete, the mixture was kept at this temperature for 1 h and then cooled to room temperature. The liquid was centrifuged three times and dried to obtain CdZnS / ZnS quantum dots. Example 1: Ultraviolet Absorption and Luminescence Performance Testing

[0102] The quantum dot samples prepared in Example 1 and Comparative Example 1 were dissolved in toluene to prepare a solution with a concentration of 0.5 mmol / ml for optical property testing. The tests were conducted using a relative method, according to national standards GB / T 37664.1-2019 and GB / T36081-2018, measuring the ultraviolet absorption and fluorescence intensity of the quantum dots. The results are as follows: Figure 1 and Figure 2 As shown.

[0103] from Figure 1 and Figure 2 As can be seen from the data, compared with Comparative Example 1, the quantum dots prepared by the method of the present invention show significantly enhanced absorption in the ultraviolet region and improved fluorescence intensity.

[0104] Experiment 2: Photovoltaic Module Performance Testing

[0105] 0.3g of quantum dots, 30g of EVA particles, 0.3g of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 0.2g of triallyl isocyanurate, 0.1g of γ-(methacryloyloxy)propyltrimethoxysilane, 0.03g of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and 0.02g of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol ester were mixed evenly and then melt-extruded and cast at 140℃ to obtain a quantum dot film with a thickness of 0.5mm.

[0106] The photovoltaic glass, quantum dot film, solar cell, quantum dot film, and lower photovoltaic glass are stacked sequentially from bottom to top on the photovoltaic glass. The stack is then placed in a vacuum laminator, evacuated for 10 minutes, heated to 120°C, and laminated under a pressure of 25 MPa to obtain the photovoltaic module.

[0107] Using quantum dots added to the encapsulant film as in Example 1 and Comparative Example 1, respectively, encapsulant films were prepared and laminated to obtain photovoltaic modules. The module power was tested and the degradation rate was calculated for comparison. The power testing standard for photovoltaic modules was IEC61215-2:2021, and the anti-PID performance testing standard was IEC61215-2:2021.

[0108] The test results are shown in Table 1.

[0109] Table 1

[0110]

[0111] Table 1 shows that, for photovoltaic modules using Example 1 and Comparative Example 1 as light conversion factors, the initial power of Example 1 is increased by approximately 0.09% compared to Comparative Example 1. This is because the quantum dots obtained in Example 1 have higher ultraviolet absorption capacity than those in Comparative Example 1, thus converting more ultraviolet light into visible light and thereby increasing the initial power of the module. After UV irradiation of 3000 kWh, the power of Example 1 can still be maintained at 97% of the initial power. This is due to the high stability of the quantum dots and the enhanced absorption of ultraviolet light by the quantum dots in Example 1, which reduces the impact of ultraviolet light on the module.

Claims

1. A method for preparing quantum dots with high ultraviolet absorption, characterized in that, The preparation method includes the following steps: 1) Prepare the precursor solution required for the reaction; Preparation of the first sulfur precursor S-ODE solution: Under argon atmosphere, 5 mmol of S was added to 10 ml of octadecene solution, heated to 120 °C and held for 60 min until the solid was completely dissolved, to obtain an S-ODE solution with a concentration of 0.5 mmol / ml, which was then kept at 100 °C for later use. Preparation of TOPS solution, a second sulfur precursor: Under argon atmosphere, 5 mmol of S was added to 10 ml of trioctylphosphine solution and stirred until the solid was completely dissolved to obtain a TOPS solution with a concentration of 0.5 mmol / ml, which was then set aside for use. Preparation of zinc precursor solution: Under argon atmosphere, add 20 mmol zinc acetate, 20 ml oleic acid and 20 ml octadecene to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear to obtain zinc precursor solution, cool down to 100℃ and keep warm for later use. 2) Preparation of quantum dot cores; 1 mmol cadmium oxide, 10 mmol zinc acetate, and 10 ml oleic acid were added to a four-necked flask and heated to 120 °C for 1 h under a nitrogen protective atmosphere. Then 20 ml octadecene was added, and the temperature was raised to 300 °C. The S-ODE solution was quickly injected and kept at this temperature for 12 min. The temperature was then lowered to room temperature, the liquid was centrifuged three times, and dried to obtain quantum dot cores. 3) Repairing quantum dot cores using ZnX solution; Preparation of ZnCl2 solution: Under argon atmosphere, add 10 mmol ZnCl2, 20 ml oleic acid and 20 ml octadecene to a four-necked flask, stir and heat to 280℃ and keep warm for 20 min until the solution is clear, then cool to 100℃ and keep warm for later use. The quantum dot nuclei were dissolved in toluene to form a solution with a concentration of 0.5 mmol / ml. 5 mmol of zinc precursor solution, 15 mmol of ZnCl2 solution and 50 ml of octadecene were added to the resulting solution. The solution was heated to 300 °C under argon protection and kept at that temperature for 1 h to obtain the repaired quantum dot nuclei. 4) The repaired quantum dot cores are coated with a precursor solution to form quantum dots with a quantum dot core-ZnX repair layer-quantum dot shell structure; 10 ml of TOPS solution is added dropwise to the repaired quantum dot core solution at a rate of 1 ml / h. After the addition is complete, the solution is kept warm for 1 h, cooled to room temperature, and the liquid is centrifuged three times and dried to obtain the CdZnS-ZnCl2 / ZnS quantum dots with high UV absorption.

2. A quantum dot with high ultraviolet absorption prepared by the preparation method of claim 1.

3. The application of the quantum dots according to claim 2 in the preparation of photovoltaic modules.

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