Preparation method for growing alloyed quantum dots in mesoporous glass at room temperature

Abstract

The invention relates to a method for growing alloyed quantum dots in mesoporous glass at room temperature, the alloyed quantum dots are CdZnS quantum dots, and the mesoporous glass is Al2O3-SiO2 mesoporous glass. The basic process of the method comprises the following steps: preparing mesoporous Al2O3-SiO2 glass containing quantum dot precursors Cd and Zn by using a water-phase chelate sol-gel method; the preparation method comprises the following steps: preparing a sol solution containing a quantum dot precursor, and carrying out sol-to-xerogel and high-temperature calcination to obtain mesoporous glass Al2O3-SiO2-Cd / Zn containing the quantum dot precursor; reacting the mesoporous glass containing the quantum dot precursor with H2S at room temperature to prepare alloyed quantum dot glass; by regulating and controlling the doping proportion of the two quantum dot precursors in the mesoporous glass, the chemical components of the grown alloyed quantum dots can be directly regulated and controlled, and the light emitting range of the alloyed quantum dot glass is regulated and controlled. The method provided by the invention provides a new scheme which does not need a high-temperature condition for growing the alloyed quantum dots in the glass.

Description

Technical Field

[0001] The invention relates to a gas phase preparation method for growing luminescent alloyed quantum dots in mesoporous glass at room temperature, and belongs to the field of optical glass preparation. Background Art

[0002] Quantum dots exhibit unique optical properties due to their quantum confinement effect. Changing their particle size can achieve regulation of the luminescence range. In situ growth and solidification of quantum dots in glass is the most promising means to improve the stability and processing performance of quantum dots. In previous work, we have changed the preparation conditions of mesoporous glass (changing the mesoporous Al 2 O 3 -SiO 2 The aluminum-silicon ratio in the glass is used to regulate the size of the mesopores in the mesoporous glass, thereby regulating the particle size of the quantum dots to achieve the regulation of its luminescence range. However, the aperture regulation range of mesoporous glass is limited, and alloyed quantum dots can change the bandgap width of the quantum dots without changing the particle size, thereby effectively regulating its luminescence range. However, there are few reports on the in-situ growth and solidification of alloyed quantum dots in glass. In the few reports that have been reported, the traditional high-temperature heat treatment method is also used to crystallize the alloyed quantum dots in dense glass [Wang, JC et al., Journal of the American Ceramic Society, 2022, 106, 1, 317-329.][PD Persans et al., Physical Review B, 63, 115320.][Yu M Azhniuk et al 2007 J. Phys.: Conf. Ser. 92, 012044.]. It is a technical difficulty to adjust the luminescence spectrum by changing the composition of quantum dots in mesoporous glass, especially at low temperature. We use the aqueous chelate sol-gel method to prepare mesoporous Al 2 O 3 -SiO 2 glass, alloyed quantum dot precursors Cd and Zn are simultaneously doped into the glass sol system, and H 2 S gas is used as a sulfur source to in-situ grow and solidify alloyed quantum dots in mesoporous glass at room temperature. At the same time, the molar ratio between the doped precursors Cd and Zn can be changed to change the bandgap width of the grown alloyed quantum dots, thus achieving effective regulation of the luminescence range of the alloyed quantum dot glass. Summary of the invention

[0003] The present invention provides a preparation method of alloyed quantum dots grown in mesoporous inorganic glass at room temperature, the purpose of which is to avoid using high-temperature heat treatment to achieve the solidification of alloyed quantum dots in a glass substrate, change the doping concentration of two quantum dot precursors, and make the prepared alloyed quantum dot glass have a wider controllable luminescence range.

[0004] The technical solution of the present invention is to propose a preparation method for growing alloyed quantum dots in mesoporous glass at room temperature, wherein two quantum dot precursors Cd and Zn are simultaneously added to a sol solution for preparing nanoporous glass to prepare a mesoporous Al containing two quantum dot precursors. 2 O 3 -SiO 2 glass, at room temperature, the mesoporous glass is placed in H 2 In an S atmosphere, alloyed quantum dots are grown in mesoporous glass. The specific method includes the following steps:

[0005] S1. Preparing a precursor solvent: adding an aqueous solution of aluminum lactate to an ethanol dispersion of TEOS, and stirring the mixture by magnetic stirring at room temperature to obtain a mixed solution;

[0006] S2. Adding quantum dot precursor: adding aqueous zinc acetate solution and aqueous cadmium acetate solution dropwise to the mixed solution obtained in step S1, stirring magnetically at room temperature until TEOS is completely hydrolyzed to obtain a clear sol system;

[0007] S3. Aging and drying: The sol system obtained in step S2 was allowed to stand at room temperature for aging, then heated in an oven to evaporate the solvent, and cooled naturally to room temperature to obtain a dry gel system;

[0008] S4. High temperature sintering: The dry gel system obtained in step S3 is placed in a muffle furnace for high temperature sintering to obtain a mesoporous glass Al containing quantum dot precursors Cd and Zn. 2 O 3 -SiO 2 -Cd / Zn;

[0009] S5. Growth of alloyed quantum dots: The mesoporous glass Al containing two quantum dot precursors obtained in step S4 is 2 O 3 -SiO 2 -Cd / Zn in H 2 In an S atmosphere, alloyed quantum dots were grown at room temperature to prepare alloyed quantum dot glass Al 2 O 3 -SiO 2 -CdZnS.

[0010] Furthermore, the Al / Si molar ratio in the mixed solution obtained in step S1 is 0.02-0.1.

[0011] Furthermore, the stirring speed of the magnetic stirring in steps S1 and S2 is 300-800 rpm.

[0012] Furthermore, in step S2, the total doping concentration of Cd and Zn in the aqueous solution of zinc acetate and cadmium acetate does not exceed 1.5 mol% of the total molar amount of Al and Si.

[0013] Furthermore, in step S2, the molar ratio of Zn / Cd in the aqueous solution of zinc acetate and cadmium acetate is 0-2.

[0014] Furthermore, in step S3, the aging time is 24 hours, and the temperature in the oven is raised by 20°C every 4 hours from room temperature to 100°C, and after being kept at 100°C for 24 hours, it is naturally cooled to room temperature.

[0015] Furthermore, in step S4, the high temperature calcination temperature of the dry gel in the muffle furnace is increased from room temperature to 650-750°C, and the temperature is maintained for 6 hours every time the temperature is increased by 100°C.

[0016] Further, in step S5, a tube furnace is used as a container for the quantum dot reaction, and H 2 Before adding S gas, the tube furnace was evacuated for 30 minutes.

[0017] Furthermore, in step S5, the growth time of the alloyed quantum dots is 24-120 hours.

[0018] Technical effects of the present invention:

[0019] (1) First, two quantum dot precursors, Cd and Zn, are simultaneously doped into the mesoporous glass system. The room temperature growth and solidification of alloyed quantum dots in the mesoporous glass can be achieved by a vapor phase method, overcoming the technical difficulty of the conventional method that requires a high temperature environment. This has previously only been achieved in dense glass by high-temperature heat treatment.

[0020] (2) Secondly, by changing the doping concentration of the two quantum dot precursors in the glass, it is possible to grow alloyed quantum dots in mesoporous glass, achieving a technological breakthrough in regulating the chemical composition of quantum dots in a fixed pore size, and solving the technical difficulty of achieving ultra-wide luminescence range regulation of ≥80 nanometers through composition adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 (a) is a TEM image of the 0.5Cd0.5ZnS quantum dot glass prepared in Example 1 of the present invention, Figure 1 (b) is the STEM image of the 0.5Cd0.5ZnS quantum dot glass prepared in Example 1.

[0022] Figure 2(a) is a TEM image of the 0.5Cd1ZnS quantum dot glass prepared in Example 2 of the present invention, Figure 2 (b) is the STEM image of the 0.5Cd1ZnS quantum dot glass prepared in Example 2.

[0023] Figure 3 It is the fluorescence spectrum of 0.5Cd0.01ZnS quantum dot glass, 0.5Cd0.5ZnS quantum dot glass and 0.5Cd1ZnS quantum dot glass prepared in Examples 1-3 of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with embodiments.

[0025] Embodiment 1:

[0026] (1) Add 3 ml of aqueous solution of aluminum lactate to 5 ml of TEOS ethanol dispersion, stir magnetically for 5 minutes, then dropwise add corresponding amounts of aqueous solutions of cadmium acetate and zinc acetate, stir magnetically at room temperature at a speed of 500 rpm until TEOS is completely hydrolyzed to obtain a clear sol system. The molar ratio of Al:Si in the sol is 0.1, and the molar concentrations of Cd and Zn added dropwise are 0.5 mol% and 0.5 mol%, respectively.

[0027] (2) The above sol solution was transferred to a culture dish and aged at room temperature for 24 hours. It was then placed in an oven and the temperature was increased by 20°C every 4 hours from room temperature to 100°C. After the temperature was increased to 100°C and kept warm for 24 hours, it was naturally cooled to room temperature to prepare a dry gel containing two quantum dot precursors.

[0028] (3) The dry gel was transferred to a crucible and placed in a muffle furnace. The high temperature calcination procedure was as follows: the temperature was raised from room temperature to 700°C, and the temperature was kept at 100°C for 6 hours. After keeping at 700°C for 6 hours, the temperature was naturally lowered to room temperature to obtain a mesoporous Al containing two quantum dot precursors. 2 O 3 -SiO 2 Glass.

[0029] (4) The glass was placed in a tube furnace and first vacuumed for 30 minutes, and then H 2 S gas was added and the growth reaction was carried out at room temperature for 120 hours to prepare luminescent alloyed quantum dot glass.

[0030] Embodiment 2:

[0031] Other implementation conditions were consistent with those in Example 1, except that the molar concentrations of Cd and Zn added dropwise into the sol system were changed to 0.5 mol% and 1 mol%.

[0032] Embodiment 3:

[0033] Other implementation conditions were consistent with those in Example 1, except that the molar concentrations of Cd and Zn added dropwise into the sol system were changed to 0.5 mol% and 0.01 mol%.

[0034] The examples are summarized in the table below.

[0035]

[0036]

[0037] Table 1: Statistical table of variables controlled in various embodiments of growing alloyed quantum dots in mesoporous glass using a vapor phase method at room temperature

[0038] in,

[0039] In Example 1 to Example 3, in a mesoporous glass with an Al:Si molar ratio of 0.1, the molar ratio of the two quantum dot precursors Cd and Zn is changed to achieve regulation of the luminescence range of the quantum dot glass over 80 nanometers.

[0040] In Examples 4 to 8, what is changed is the growth time of the alloy quantum dots, which has a regulatory effect on the fluorescence lifetime of the alloy quantum dot glass.

[0041] In Example 9-Example 11, in a mesoporous glass with an Al:Si molar ratio of 0.05, the molar ratio of the two quantum dot precursors Cd and Zn is changed, thereby changing the chemical composition of the alloyed quantum dots.

[0042] In Example 12-Example 14, the Al:Si molar ratio in the glass system is changed, and the alloy quantum dots can be successfully grown in mesoporous glasses with different Al:Si molar ratios.

[0043] In Examples 15 to 17, what is changed is the calcination temperature during the preparation of the glass. The glasses prepared within this temperature range all have mesoporous properties.

[0044] In Example 18 and Example 19, the stirring speed during the mixing of the sol is changed. The stirring speed within this range can achieve uniform doping of the glass component sol system.

Claims

1. A method for preparing alloyed quantum dots grown in mesoporous glass at room temperature, characterized in that: Two quantum dot precursors Cd and Zn are added simultaneously to a sol solution for preparing nanoporous glass to prepare mesoporous Al2O3-SiO2 glass containing two quantum dot precursors. At room temperature, the mesoporous glass is placed in a H2S atmosphere to grow alloyed quantum dots in the mesoporous glass. The specific method includes the following steps: S1. Preparing a precursor solvent: adding an aqueous solution of aluminum lactate to an ethanol dispersion of TEOS, and stirring the mixture by magnetic stirring at room temperature to obtain a mixed solution; S2. Adding quantum dot precursor: adding aqueous zinc acetate solution and aqueous cadmium acetate solution dropwise to the mixed solution obtained in step S1, stirring magnetically at room temperature until TEOS is completely hydrolyzed to obtain a clear sol system; S3. Aging and drying: The sol system obtained in step S2 was allowed to stand at room temperature for aging, then heated in an oven to evaporate the solvent, and cooled naturally to room temperature to obtain a dry gel system; S4 high temperature sintering: The dry gel system obtained in step S3 is placed in a muffle furnace and sintered at high temperature to obtain a mesoporous glass Al2O3-SiO2-Cd / Zn containing quantum dot precursors Cd and Zn; S5. Growth of alloyed quantum dots: The mesoporous glass Al2O3-SiO2-Cd / Zn containing two quantum dot precursors obtained in step S4 is placed in a H2S atmosphere, and alloyed quantum dots are grown at room temperature to prepare alloyed quantum dot glass Al2O3-SiO2-CdZnS.

2. The method for preparing alloyed quantum dots grown in mesoporous glass at room temperature according to claim 1, characterized in that: The Al / Si molar ratio in the mixed solution obtained in step S1 is 0.02 to 0.

1.

3. The method for preparing alloyed quantum dots grown in mesoporous glass at room temperature according to claim 1, characterized in that: The stirring speed of the magnetic stirring in steps S1 and S2 is 300-800 rpm.

4. The method for preparing alloyed quantum dots grown in mesoporous glass at room temperature according to claim 1, characterized in that: In step S2, the total doping concentration of Cd and Zn in the aqueous solution of zinc acetate and cadmium acetate does not exceed 1.5 mol% of the total molar amount of Al and Si.

5. The method for preparing alloyed quantum dots grown in mesoporous glass at room temperature according to claim 1, characterized in that: In step S2, the molar ratio of Zn / Cd in the aqueous solution of zinc acetate and cadmium acetate is 0-2.

6. The method for preparing alloyed quantum dots grown in mesoporous glass at room temperature according to claim 1, characterized in that: In step S3, the aging time is 24 hours, and the temperature in the oven is raised by 20°C every 4 hours from room temperature to 100°C, and after being kept at 100°C for 24 hours, it is naturally cooled to room temperature.

7. The method for preparing alloyed quantum dots grown in mesoporous glass at room temperature according to claim 1, characterized in that: In step S4, the high temperature calcination temperature of the dry gel in the muffle furnace is increased from room temperature to 650-750°C, and the temperature is maintained for 6 hours every time the temperature is increased by 100°C.

8. The method for preparing alloyed quantum dots grown in mesoporous glass at room temperature according to claim 1, characterized in that: In step S5, a tube furnace is used as a container for quantum dot reaction, and the tube furnace is evacuated for 30 minutes before the H2S gas is introduced.

9. The method for preparing alloyed quantum dots grown in mesoporous glass at room temperature according to claim 1, characterized in that: In step S5, the growth time of the alloyed quantum dots is 24-120 hours.

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