Gram-level synthesis method of wavelength-adjustable high-fluorescence-efficiency quantum dot material CuInxGa1-xS2 / ZnS

Abstract

The invention provides a gram-level synthesis method of a wavelength-adjustable quantum dot material CuIn < x > Ga < 1-x > S < 2 > / ZnS with high fluorescence efficiency. The CuIn < x > Ga < 1-x > S2 quantum dots are synthesized by heating a copper source, an indium source and a gallium source in a solvent to react. A Zn precursor solution is thermally injected for one time, and the CuIn < x > Ga < 1-x > S < 2 > / ZnS core-shell quantum dot is further synthesized. According to the CuIn < x > Ga < 1-x > S < 2 > / ZnS quantum dot prepared in the invention, by controlling the proportion of the indium source and the gallium source, the change of the light-emitting central wavelength of 600nm-800nm can be realized; the highest fluorescence efficiency of the CuIn < x > Ga < 1-x > S < 2 > / ZnS quantum dot prepared in the invention can be close to 100%.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum dot material preparation, and particularly to a method for gram-scale synthesis of a wavelength-tunable quantum dot material CuIn x Ga 1-x S2 / ZnS. Background Art

[0002] Quantum dot materials are the key core materials in nano-optoelectronic technology and are widely used in fields such as solar cells, multi-modal biomedical diagnosis and treatment integration, intelligent flexible optoelectronic systems, photocatalysis and clean energy, and encryption and information security. The optimization of their performance and the breakthrough of synthesis processes are of great significance for promoting the upgrading of related industries. Although traditional cadmium (Cd)-based quantum dots (such as CdSe) have relatively high fluorescence efficiency, they have problems such as heavy metal toxicity (such as Cd 2+ leaching risk) and narrow emission spectra (usually full width at half maximum <50 nm), which limit their applications in environmentally sensitive fields and wide color gamut displays. In contrast, copper-based ternary quantum dots have attracted much attention due to their low toxicity (meeting the RoHS standard), wide emission spectrum tunability, and low cost. However, there are still some problems with the representative material CuInS2 quantum dots among copper-based ternary quantum dots. In terms of synthesis methods, CuInS2 quantum dots face many challenges: First, the existing synthesis methods have a long synthesis time, complex steps, and a long shell growth time, resulting in low production efficiency; second, a large amount of raw materials is required, but the corresponding yield is not high; third, there is still room for improvement in fluorescence efficiency and it has not reached the ideal level; finally, large-scale production is difficult, and the yield of traditional methods is relatively low, and innovative methods are needed to improve batch consistency and reduce energy consumption.

[0003] In view of the above problems, the synthesis method proposed by the present invention shortens the synthesis time, simplifies the experimental steps, and at the same time successfully realizes the gram-scale synthesis of quantum dots, improving the yield. By introducing Ga 3+ ions and ZnS shell coating, the passivation of the interface defects of the core-shell structure is achieved, the fluorescence efficiency is increased to more than 90%, and the highest fluorescence efficiency is close to 100%, and the chemical stability of the quantum dots is significantly enhanced. After being stored at room temperature for half a year, the optical properties have no obvious change. At the same time, precise regulation of the emission wavelength is achieved by adjusting the ratio of In:Ga. Summary of the Invention

[0004] In view of the above problems in the prior art, the present application proposes a method for gram-scale synthesis of a wavelength-tunable quantum dot material CuIn x Ga 1-x S2 / ZnS, which effectively inhibits the formation of defects in the quantum dots and passivates the surface of the quantum dots. By introducing Ga 3+The fluorescence efficiency is improved, and the high-quality synthesis of gram-scale quantum dots is realized.

[0005] The technical solution of the present invention is as follows:

[0006] A. Prepare the precursor solution: Put the zinc source and oleic acid into a three-necked flask containing thiol, heat it to 90°C - 110°C under a nitrogen atmosphere, keep it for 30 minutes, and then raise the temperature to 200°C - 240°C to obtain the precursor solution;

[0007] B. Add the copper source, indium source, and gallium source to a three-necked flask containing thiol, raise the temperature to 90°C - 110°C under a nitrogen atmosphere, keep it for 0 - 30 min, and then continue to raise the temperature to 200°C - 240°C, and keep it for 0 - 60 min;

[0008] C. Quickly inject the precursor solution obtained in A into the hot solution obtained in B, and then carry out a heating reaction in an inert gas environment, keep it at 200°C - 240°C for 0 - 60 min, and then naturally cool to room temperature. Add a polar solvent for centrifugal separation, remove the supernatant, and disperse the precipitate in a non-polar solvent to obtain CuIn x Ga 1-x S2 / ZnS quantum dots.

[0009] The above technical features can be combined in various suitable ways or replaced by equivalent technical features as long as the purpose of the present invention can be achieved.

[0010] A method for synthesizing gram-scale CuIn x Ga 1-x S2 / ZnS quantum dot materials with adjustable wavelength and high fluorescence efficiency provided by the present invention has at least the following beneficial effects compared with the prior art:

[0011] Compared with the CuInS2 / ZnS quantum dots synthesized by the traditional method, the CuIn x Ga 1-x S2 / ZnS quantum dots in the present invention are synthesized by a two-step method, which shortens the synthesis time, simplifies the synthesis steps, and reduces the long shell time. By introducing Ga 3+ ions to passivate the electronic defects and coating the ZnS shell to passivate the surface defects of CuInGaS2, the surface quenching effect is effectively reduced, the fluorescence efficiency is improved, the highest fluorescence efficiency is close to 100%, and the stability of the quantum dots is improved. At the same time, by adjusting the ratio of In:Ga, the precise regulation of the emission wavelength is realized, and the span of the emission center wavelength can reach 600 nm - 800 nm. This synthesis method is efficient and simple, realizes the synthesis of gram-scale quantum dots, and can realize large-scale preparation in the laboratory. Description of the Drawings

[0012] The present invention will be described in more detail below based on embodiments with reference to the accompanying drawings.

[0013] Wherein:

[0014] Figure 1 is the transmission electron microscope image of the CuIn x Ga 1-x S2 quantum dots prepared in step A.

[0015] Figure 2 is the transmission electron microscope image of the CuIn x Ga 1-x S2 / ZnS core-shell quantum dots prepared in step C.

[0016] Figure 3 is the X-ray diffraction pattern of the CuIn x Ga 1-x S2 quantum dots before and after shell modification.

[0017] Figure 4 is the normalized absorption and fluorescence spectra of the CuIn x Ga 1-x S2 / ZnS core-shell quantum dots prepared in the present invention.

[0018] Figure 5 is the normalized absorption and fluorescence spectra of the CuIn x Ga 1-x S2 / ZnS core-shell quantum dots prepared in the present invention.

[0019] Figure 6 is the time-resolved fluorescence decay curve of the CuIn x Ga 1-x S2 quantum dots before and after ZnS shell modification prepared in the present invention.

[0020] Figure 7 is the change diagram of the emission center wavelength and fluorescence efficiency of the CuInxGa 1-x S2 / ZnS core-shell quantum dots prepared in the present invention at different ratios of indium source to gallium source. Detailed Embodiments

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention, the applicant will further elaborate on the present invention in combination with specific embodiments and the accompanying drawings below. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0022] In one embodiment, 1.5 mmol of copper iodide, 1.2 mmol of indium acetate, 0.3 mmol of gallium acetate and 10 mL of 1-dodecanethiol were added to a three-necked flask. The temperature was raised to 120 °C under a nitrogen atmosphere and maintained for 25 min, then the temperature was further raised to 240 °C and maintained for 30 min, and then it was naturally cooled to room temperature. Ethanol was added for centrifugal separation, and the supernatant was removed. The precipitate was dispersed in a non-polar solvent to obtain CuIn 0.8 Ga 0.2 S2 quantum dots, Figure 1 which is the transmission electron microscope image thereof.

[0023] In one embodiment, 1 mmol of zinc acetate, 8 mL of oleic acid and 2 mL of hexanethiol were placed in a three-necked flask. The mixture was heated to 120 °C under a nitrogen atmosphere and maintained for 30 minutes, and then the temperature was raised to 240 °C to obtain a precursor solution; 1 mmol of copper chloride, 1.2 mmol of indium acetate, 0.3 mmol of gallium acetate and 10 mL of hexanethiol were added to the three-necked flask. The temperature was raised to 100 °C under a nitrogen atmosphere and maintained for 15 min, then the temperature was further raised to 230 °C and maintained for 30 min to obtain a hot solution. The precursor solution was rapidly injected into this hot solution, and then a heating reaction was carried out in an inert gas atmosphere, maintained at 230 °C for 35 min, and then naturally cooled to room temperature. Ethanol was added for centrifugal separation, and the supernatant was removed. The precipitate was dispersed in a non-polar solvent to obtain CuIn 0.8 Ga 0.2 S2 / ZnS quantum dots, Figure 2 which is the transmission electron microscope image thereof. By comparison Figure 1 Figure 2 it can be seen that the size becomes larger after coating. The obtained X-ray diffraction pattern is as Figure 3 shown, further confirming that the synthesized quantum dots are CuIn x Ga 1-x S2 quantum dots and CuIn x Ga 1-x S2 / ZnS quantum dots.

[0024] In one embodiment, 1 mmol of zinc acetate, 8 mL of oleic acid, and 2 mL of DDT are placed in a three-necked flask and heated to 120 °C in a nitrogen environment. After maintaining for 30 minutes, the temperature is raised to 240 °C to obtain a precursor solution. 1 mmol of copper iodide, 0.9 mmol of indium acetate, 0.1 mmol of gallium acetate, and 10 mL of DDT are added to the three-necked flask and the temperature is raised to 100 °C in a nitrogen environment. After maintaining for 15 min, the temperature is then further raised to 230 °C and maintained for 30 min to obtain a hot solution. The precursor solution is rapidly injected into the hot solution, and then a heating reaction is carried out in an inert gas environment. It is maintained at 230 °C for 35 min and then naturally cooled to room temperature. Ethanol is added for centrifugal separation, and the supernatant is removed. The precipitate is dispersed in a non-polar solvent to obtain CuIn 0.9 Ga 0.1 S2 / ZnS quantum dots.

[0025] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not depart from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A gram-scale synthesis method of wavelength-tunable high-fluorescence-efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS, characterized in that It includes the following steps: A. Prepare the precursor solution: Put a zinc source and oleic acid into a three-necked flask containing thiol, heat it to 90°C - 110°C under a nitrogen atmosphere, keep it for 30 minutes, and then raise the temperature to 200°C - 240°C to obtain the precursor solution; B. Add a copper source, an indium source, and a gallium source to a three-necked flask containing thiol, raise the temperature to 90°C - 110°C under a nitrogen atmosphere, keep it for 0 - 30 min, then continue to raise the temperature to 200°C - 240°C, and keep it for 0 - 60 min; C. Rapidly inject the precursor solution obtained in A into the hot solution obtained in B, and then carry out a heating reaction in an inert gas environment, maintain at 200 °C - 240 °C for 0 - 60 min, and then naturally cool to room temperature. Add a polar solvent for centrifugal separation, remove the supernatant, and disperse the precipitate in a non-polar solvent to obtain CuIn x Ga 1-x S2 / ZnS quantum dots.

2. The gram-scale synthesis method of the wavelength-tunable high-fluorescence-efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS, characterized in that In step A, the zinc source is one or more of zinc acetate, zinc stearate, and zinc chloride, and the thiol is one or more of n-dodecyl mercaptan and hexyl mercaptan.

3. The gram-scale synthesis method of the wavelength-tunable high-fluorescence-efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS, characterized in that, In step B, the copper source is one or more of copper iodide, copper chloride, and cuprous chloride, the indium source is one or more of indium acetate and indium chloride, the gallium source is one or more of gallium acetate and gallium acetylacetonate, and the thiol is one or more of n-dodecyl mercaptan and hexyl mercaptan.

4. The gram-scale synthesis method of wavelength-tunable high-fluorescence-efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS, characterized in that This synthesis method can achieve the preparation of gram-scale quantum dots.

5. The wavelength-tunable high fluorescence efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS prepared by a gram-scale synthesis method, the wavelength-tunable high fluorescence efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS, characterized in that The fluorescence efficiency can reach more than 90%, and the highest fluorescence efficiency can be close to 100%.

6. The wavelength-tunable high fluorescence efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS prepared by a gram-scale synthesis method, the wavelength-tunable high fluorescence efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS, characterized in that It has good stability. When stored at room temperature for half a year, the optical properties have no obvious change.

7. The wavelength-tunable high fluorescence efficiency quantum dot material CuIn x Ga 1-x The wavelength-tunable high fluorescence efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS prepared by a gram-scale synthesis method, characterized in that The size is concentrated at about 1.41 nm, which are ultra-small quantum dots.

8. The copper source in the gram-scale synthesis method of the wavelength-tunable high-fluorescence-efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS can be replaced by a silver source, and the quantum dot AgIn x Ga 1-x S2 / ZnS can be prepared by the same synthesis method, and the silver source is one or more of silver chloride and silver acetate.

9. The indium source in the gram-scale synthesis method of the wavelength-tunable high-fluorescence-efficiency quantum dot material CuIn x Ga 1-x S2 / ZnS can be replaced by an aluminum source, and the quantum dot CuAl x Ga 1-x S2 / ZnS can be prepared by the same synthesis method, and the aluminum source is one or more of aluminum chloride and aluminum acetate.

10. The wavelength-tunable high fluorescence efficiency quantum dot material CuIn x Ga 1-x S 2 / In the B step of the gram-scale synthesis method of ZnS, a selenium source can be introduced. The selenium source is dissolved in oleylamine and thiol and then added to the flask. The quantum dots CuIn x Ga 1-x Se x S 2-x / ZnS can be prepared by the same synthesis method, and the selenium source is selenium powder.

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