Plasmon core-shell quantum dot and preparation method thereof
Through room temperature magnetic stirring and ultrafiltration centrifugal reaction, plasmon core-shell quantum dots were prepared, solving the problem of limited fluorescence performance of gold or silver quantum dots, achieving high luminescence intensity and adjustable luminescence wavelength, and suitable for the application of optoelectronic technology.
Patent Information
- Application Number
- CN202411594789.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-10
- Publication Date
- 2025-02-25
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of quantum dot luminescent materials, and in particular relates to a plasmon core-shell quantum dot and a preparation method thereof. Background Art
[0002] The fluorescence of metal quantum dots has attracted great attention in the fields of chemistry, materials and biology. The fluorescence of metal quantum dots has been extensively studied, especially for gold and silver. However, the limited quantum yield and fluorescence emission of gold or silver quantum dots restrict their applications. The scientific study of gold nanoparticles did not begin until the middle of the 19th century, and their electronic excitation was understood as the collective excitation mode of the conduction electrons in the particles, the so-called surface plasmon resonance. Since the 1990s, we have witnessed tremendous research work on the shape and size control of gold nanoparticles, as well as exploring their technological applications in nanoelectronics and optics, biosensing, catalysis and biomedicine. Compared with bare quantum dots, core-shell quantum dots have stability and rich luminescence properties, making them a promising class of materials in future optoelectronic technologies.
[0003] Core-shell structural engineering is an attractive approach to develop new functional materials in various fields such as semiconductors, magnetic materials and catalysts, which can achieve the electronic structure regulation between the core and the shell. Given these advantages, core-shell nanocrystals are designed to significantly enhance the fluorescence and quantum yield of the materials. Similarly, core-shell structural engineering also helps to regulate the electronic structure of Au or Ag quantum dots to improve their fluorescence properties. In addition, the higher electronegativity of Au relative to Ag can drive the transfer of electrons from Ag to Au. However, it is so difficult to construct core-shell structures on such a small scale that there are few reports on quantum dots with gold or silver core-shell structures. Summary of the invention
[0004] One of the purposes of the present invention is to provide a method for preparing plasmon core-shell quantum dots. The plasmon core-shell quantum dots prepared by this method have high luminescence intensity, high quantum yield, adjustable luminescence wavelength and adjustable excitation wavelength, and can be used to prepare luminescent gratings and display devices.
[0005] A second object of the present invention is to provide a plasmon core-shell quantum dot.
[0006] In order to achieve one of the above purposes, the present invention adopts the following technical solution:
[0007] A method for preparing plasmon core-shell quantum dots, the preparation method comprising the following steps:
[0008] Step S1, adding silver nitrate and sodium hydroxide to methylthiouracil, and then performing magnetic stirring at a temperature of 20 to 35° C., and then performing ultrafiltration centrifugation in an ultrafiltration centrifuge tube to obtain a plasmon core-shell quantum dot inner layer silver core solution;
[0009] Step S2, adding sodium hydroxide, chloroauric acid, and methylthiouracil to the inner silver core solution of plasmon core-shell quantum dots, and then performing magnetic stirring at a temperature of 20 to 35° C. to obtain plasmon core-shell quantum dots.
[0010] Furthermore, in step S1, the volume ratio of the silver nitrate, sodium hydroxide and methylthiouracil is 0.045-0.137:0.032:1.
[0011] Furthermore, in step S1, the molar concentrations of the silver nitrate, sodium hydroxide and methylthiouracil are 20-30 mmol / L, 0.9-1.1 mol / L and 8-10 mmol / L, respectively.
[0012] Furthermore, in the step S1, the magnetic stirring rate is 750-850 rpm / min, and the time is 1.4-2.2 h.
[0013] Furthermore, in step S1, the molecular weight cutoff of the ultrafiltration centrifuge tube is 10Kda. The unreacted precursor can be quickly filtered through the ultrafiltration centrifuge tube to avoid the disappearance of the fluorescence effect due to excessive reaction. The pore size of 10KDa can not only retain the inner silver core of the plasmon core-shell quantum dots, but also quickly filter the precursor.
[0014] The ultrafiltration centrifugation speed is 6000-7000 rpm / min, and the time is 25-35 min.
[0015] Furthermore, in step S2, the volume ratio of the sodium hydroxide, chloroauric acid, methylthiouracil and the inner silver core solution of the plasmon core-shell quantum dot is 0.032: 0.034-0.18: 1: 1.07-1.17. The radius length of the silver core and the outer shell of the gold-silver alloy is controlled by the concentration of chloroauric acid and the nitrate in step S1, thereby controlling the electron injection concentration of the inner silver core to the outer shell of the gold-silver alloy, and the plasmon coupling strength between the core and the shell, thereby controlling the fluorescence emission wavelength.
[0016] Furthermore, in step S2, the molar concentrations of the sodium hydroxide, chloroauric acid and methylthiouracil are 0.9-1.1 mol / L, 20-30 mmol / L and 8-10 mmol / L, respectively.
[0017] Furthermore, in the step S2, the magnetic stirring rate is 750-850 rpm / min, and the time is 3.6-4.2 h.
[0018] In order to achieve the second objective above, the present invention adopts the following technical solution:
[0019] A plasmon core-shell quantum dot is prepared by the above-mentioned preparation method.
[0020] In summary, the solution proposed by the present invention has the following technical effects:
[0021] The invention obtains a plasmon core-shell quantum dot inner layer silver core solution by room temperature magnetic stirring reaction and ultrafiltration centrifugation of silver nitrate, sodium hydroxide and methylthiouracil; then utilizes room temperature magnetic stirring reaction between sodium hydroxide, chloroauric acid, methylthiouracil and the plasmon core-shell quantum dot inner layer silver core solution to ensure that a gold-silver alloy outer layer shell grows on the inner layer silver core of the plasmon core-shell quantum dot, thereby forming a plasmon core-shell quantum dot; the plasmon core-shell quantum dot of the invention improves quantum yield and enhances fluorescence emission through electron transfer induced by plasmon effect; in the plasmon core-shell quantum dot of the invention, the higher electronegativity of gold relative to silver drives the electron transfer from the inner layer silver of the core-shell structure to the outer layer The gold in the core-shell structure leads to the depletion of d electrons in silver and the increase of d electrons in gold. The electrons in the extra d orbital of the silver core are injected into the gold shell, activating a new electron transition pathway of the gold x shell. The new energy band structure and more efficient electron transfer mode caused by the core-shell structure jointly increase the excitation peak of the metal quantum dots, enhance the luminescence intensity of the metal quantum dots, and improve the quantum yield of the metal quantum dots. The luminescence wavelength and excitation wavelength of the plasmon core-shell quantum dots of the present invention are adjustable, and can be used to prepare luminescent gratings and display devices. The present invention adopts a hydrothermal method, and the normal temperature and pressure method is simple and easy to operate, which provides a certain reference for the preparation of high-performance luminescent materials and optical devices, has broad market prospects, and is suitable for large-scale promotion and application. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0023] Embodiment 1:
[0024] Step S1, adding silver nitrate with a molar concentration of 25 mmol / L and sodium hydroxide with a molar concentration of 1.0 mol / L to methylthiouracil with a molar concentration of 9 mmol / L, and then magnetically stirring for 2.0 h at a rate of 800 rpm / min at a temperature of 25°C, and then ultrafiltration centrifugation for 30 min at a rate of 6500 rpm / min using an ultrafiltration centrifuge tube with a molecular weight cutoff of 10 KDa to obtain a plasmon core-shell quantum dot inner layer silver core solution.
[0025] Among them, the volume ratio of silver nitrate, sodium hydroxide and methylthiouracil is 0.09:0.032:1.
[0026] Step S2, adding sodium hydroxide with a molar concentration of 1.0 mol / L, chloroauric acid with a molar concentration of 25 mmol / L, and methylthiouracil with a molar concentration of 9 mmol / L to the inner silver core solution of the plasmon core-shell quantum dots, and then magnetically stirring at a temperature of 30°C and a rate of 800 rpm / min for 4.0 h to obtain plasmon core-shell quantum dots.
[0027] Among them, the volume ratio of sodium hydroxide, chloroauric acid, methylthiouracil and the inner layer silver core solution of plasmon core-shell quantum dots is 0.032:0.14:1:1.10.
[0028] The particle size of the inner silver core of the plasmon core-shell quantum dots of this embodiment is 4nm, and the particle size of the plasmon core-shell quantum dots is 9.7nm. The emission wavelength of the plasmon core-shell quantum dots is uniformly adjustable at 479-493nm, with a plasmon peak at 424nm and excitation peaks at 372nm and 420nm. The luminous intensity of the plasmon core-shell quantum dots of this embodiment is 3293 photons per second.
[0029] In the display device prepared by the plasmon core-shell quantum dots of this embodiment, the spacing between each display pixel is 5.5 um, and the spacing between each slit is 3.9 um.
[0030] Embodiment 2:
[0031] Step S1, adding silver nitrate with a molar concentration of 20 mmol / L and sodium hydroxide with a molar concentration of 0.9 mol / L to methylthiouracil with a molar concentration of 8 mmol / L, and then magnetically stirring for 1.4 h at a rate of 750 rpm / min at a temperature of 20°C, and then ultrafiltration centrifugation for 25 min at a rate of 6000 rpm / min using an ultrafiltration centrifuge tube with a molecular weight cutoff of 10 KDa to obtain a plasmon core-shell quantum dot inner layer silver core solution.
[0032] Among them, the volume ratio of silver nitrate, sodium hydroxide and methylthiouracil is 0.045:0.032:1.
[0033] Step S2, adding sodium hydroxide with a molar concentration of 0.9 mol / L, chloroauric acid with a molar concentration of 20 mmol / L, and methylthiouracil with a molar concentration of 8 mmol / L to the inner silver core solution of the plasmon core-shell quantum dots, and then magnetically stirring for 3.6 hours at a temperature of 20°C and a rate of 750 rpm / min to obtain plasmon core-shell quantum dots.
[0034] Among them, the volume ratio of sodium hydroxide, chloroauric acid, methylthiouracil and the inner layer silver core solution of plasmon core-shell quantum dots is 0.032:0.034:1:1.07.
[0035] The particle size of the inner layer silver core of the plasmon core-shell quantum dots of this embodiment is 4.2nm, and the particle size of the plasmon core-shell quantum dots is 9.5nm. The emission wavelength of the plasmon core-shell quantum dots is uniformly adjustable at 479-493nm, with a plasmon peak at 424nm and excitation peaks at 372nm and 420nm. The luminous intensity of the plasmon core-shell quantum dots of this embodiment is 1345 photons per second.
[0036] In the display device prepared by the plasmon core-shell quantum dots of this embodiment, the spacing between each display pixel is 5.3 um, and the spacing between each slit is 3.7 um.
[0037] Embodiment 3:
[0038] Step S1, adding silver nitrate with a molar concentration of 30 mmol / L and sodium hydroxide with a molar concentration of 1.1 mol / L to methylthiouracil with a molar concentration of 10 mmol / L, and then magnetically stirring for 2.2 hours at a rate of 850 rpm / min at a temperature of 35°C, and then ultrafiltration centrifugation for 35 minutes at a rate of 7000 rpm / min using an ultrafiltration centrifuge tube with a molecular weight cutoff of 10 KDa to obtain a plasmon core-shell quantum dot inner layer silver core solution.
[0039] Among them, the volume ratio of silver nitrate, sodium hydroxide and methylthiouracil is 0.137:0.032:1.
[0040] Step S2, adding sodium hydroxide with a molar concentration of 1.1 mol / L, chloroauric acid with a molar concentration of 30 mmol / L, and methylthiouracil with a molar concentration of 10 mmol / L to the inner silver core solution of the plasmon core-shell quantum dots, and then magnetically stirring at a temperature of 35° C. and a rate of 850 rpm / min for 4.2 h to obtain plasmon core-shell quantum dots.
[0041] Among them, the volume ratio of sodium hydroxide, chloroauric acid, methylthiouracil and the inner layer silver core solution of plasmon core-shell quantum dots is 0.032:0.18:1:1.17.
[0042] The particle size of the inner layer silver core of the plasmon core-shell quantum dots of this embodiment is 3.8nm, and the particle size of the plasmon core-shell quantum dots is 9.9nm. The emission wavelength of the plasmon core-shell quantum dots is uniformly adjustable at 479-493nm, with a plasmon peak at 424nm and excitation peaks at 372nm and 420nm. The luminous intensity of the plasmon core-shell quantum dots of this embodiment is 1764 photons per second.
[0043] In the display device prepared by the plasmon core-shell quantum dots of this embodiment, the spacing between each display pixel is 5.6 um, and the spacing between each slit is 3.8 um.
[0044] Embodiment 4:
[0045] Step S1, adding silver nitrate with a molar concentration of 28 mmol / L and sodium hydroxide with a molar concentration of 1.05 mol / L to methylthiouracil with a molar concentration of 9.5 mmol / L, and then magnetically stirring for 1.8 hours at a rate of 820 rpm / min at a temperature of 32° C., and then using an ultrafiltration centrifuge tube with a molecular weight cutoff of 10 KDa, ultrafiltration centrifugation (25 to 35 min) at a rate of 6800 rpm / min for 32 minutes to obtain a plasmon core-shell quantum dot inner layer silver core solution.
[0046] Among them, the volume ratio of silver nitrate, sodium hydroxide and methylthiouracil is 0.125:0.032:1.
[0047] Step S2, adding sodium hydroxide with a molar concentration of 1.05 mol / L, chloroauric acid with a molar concentration of 28 mmol / L, and methylthiouracil with a molar concentration of 9.5 mmol / L to the inner silver core solution of the plasmon core-shell quantum dots, and then magnetically stirring for 3.8 hours at a temperature of 25°C and a rate of 820 rpm / min to obtain plasmon core-shell quantum dots.
[0048] Among them, the volume ratio of sodium hydroxide, chloroauric acid, methylthiouracil and the inner layer silver core solution of plasmon core-shell quantum dots is 0.032:0.16:1:1.13.
[0049] The particle size of the inner silver core of the plasmon core-shell quantum dots of this embodiment is 4.5nm, and the particle size of the plasmon core-shell quantum dots is 10.1nm. The emission wavelength of the plasmon core-shell quantum dots is uniformly adjustable at 479-493nm, with a plasmon peak at 424nm and excitation peaks at 372nm and 420nm. The luminous intensity of the plasmon core-shell quantum dots of this embodiment is 2691 photons per second.
[0050] In the display device prepared by the plasmon core-shell quantum dots of this embodiment, the spacing between each display pixel is 5.8 um, and the spacing between each slit is 4.2 um.
[0051] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all belong to the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.
Claims
1. A method for preparing plasmon core-shell quantum dots, characterized in that: The preparation method comprises the following steps: Step S1, adding silver nitrate and sodium hydroxide to methylthiouracil, and then performing magnetic stirring at a temperature of 20 to 35° C., and then performing ultrafiltration centrifugation in an ultrafiltration centrifuge tube to obtain a plasmon core-shell quantum dot inner layer silver core solution; Step S2, adding sodium hydroxide, chloroauric acid, and methylthiouracil to the inner silver core solution of plasmon core-shell quantum dots, and then performing magnetic stirring at a temperature of 20 to 35° C. to obtain plasmon core-shell quantum dots.
2. The preparation method according to claim 1, characterized in that: In the step S1, the volume ratio of the silver nitrate, sodium hydroxide and methylthiouracil is 0.045-0.137:0.032:
1.
3. The preparation method according to claim 2, characterized in that: In the step S1, the molar concentrations of the silver nitrate, sodium hydroxide and methylthiouracil are 20-30 mmol / L, 0.9-1.1 mol / L and 8-10 mmol / L respectively.
4. The preparation method according to claim 3, characterized in that: In the step S1, the magnetic stirring rate is 750-850 rpm / min, and the time is 1.4-2.2 h.
5. The preparation method according to any one of claims 1 to 4, characterized in that: In the step S1, the molecular weight cut-off of the ultrafiltration centrifuge tube is 10KDa; The ultrafiltration centrifugation speed is 6000-7000 rpm / min, and the time is 25-35 min.
6. The preparation method according to claim 5, characterized in that: In the step S2, the volume ratio of the sodium hydroxide, chloroauric acid, methylthiouracil and the plasmon core-shell quantum dot inner layer silver core solution is 0.032:0.034-0.18:1:1.07-1.
17.
7. The preparation method according to claim 6, characterized in that: In step S2, the molar concentrations of the sodium hydroxide, chloroauric acid and methylthiouracil are 0.9-1.1 mol / L, 20-30 mmol / L and 8-10 mmol / L respectively.
8. The preparation method according to claim 7, characterized in that: In the step S2, the magnetic stirring rate is 750-850 rpm / min, and the time is 3.6-4.2 h.
9. A plasmonic core-shell quantum dot, characterized in that: The plasmon core-shell quantum dots are prepared by the preparation method described in any one of claims 1 to 8.