Alloyed fluorescent quantum dots and their preparation method and application

Abstract

The present invention discloses an alloyed fluorescent quantum dot and a preparation method and application thereof. The preparation method comprises: subjecting a first uniformly mixed reaction system comprising a silver source, an anion source, and a weakly polar solvent to a solvothermal reaction to obtain a silver-based quantum dot precursor; subjecting a second uniformly mixed reaction system comprising a silver-based quantum dot precursor, an anion source, and / or a metal cation source to an ion exchange reaction to obtain an alloyed fluorescent quantum dot, whose fluorescence emission peak wavelength is located at 500 to 1700 nm, and whose absolute quantum efficiency is greater than 85%. The present invention first prepares silver-based quantum dots by a simple high-temperature solvothermal method, and then obtains alloyed quantum dots by an ion exchange method. The synthesis process is simple and controllable, and the yield is high. It can be prepared on a large scale, and the fluorescence emission is adjustable from visible light to near infrared, and has excellent photostability. At the same time, it does not contain any toxic heavy metal elements, and has broad application prospects in the fields of biological imaging, near-infrared devices, etc.

Description

Technical Field

[0001] The invention relates to alloyed fluorescent quantum dots and a preparation method and application thereof, belonging to the technical field of material science. Background Art

[0002] As an excellent fluorescent luminescent material, quantum dots have the following characteristics: high biocompatibility, high quantum efficiency, adjustable excitation and emission wavelengths, and easy surface functionalization, etc., and are widely used in research on in vivo imaging, light-emitting diodes, photodetectors, lasers, photovoltaic cells, etc. However, the existing fluorescent quantum dots, such as lead sulfide, cadmium telluride, lead selenide, mercury telluride, silver selenide, etc., have low absolute fluorescence quantum yields, or some contain toxic heavy metal elements, and it is difficult to achieve both fluorescence intensity and toxicity. Therefore, it is urgent to develop a new type of fluorescent quantum dot material with continuously adjustable single emission, high fluorescence quantum efficiency and high biocompatibility in the visible-near infrared full window (500-1700nm). Summary of the invention

[0003] The main purpose of the present invention is to provide an alloyed fluorescent quantum dot with high quantum efficiency and a preparation method and application thereof, thereby overcoming the deficiencies in the properties of existing quantum dots.

[0004] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0005] The embodiment of the present invention provides a method for preparing alloyed fluorescent quantum dots, which comprises:

[0006] A first uniformly mixed reaction system including a silver source, an anion source, and a weakly polar solvent is subjected to a solvothermal reaction to obtain a silver-based quantum dot precursor;

[0007] The second uniformly mixed reaction system including the silver-based quantum dot precursor, the anion source and / or the metal cation source is subjected to an ion exchange reaction at 0 to 260° C. for 0.4 to 72 hours to obtain alloyed fluorescent quantum dots.

[0008] In some embodiments, the anion source includes any one or a combination of two or more of a sulfur source, a selenium source, and a tellurium source.

[0009] In some embodiments, the metal elements contained in the metal cation source include any one or a combination of two or more of Mn, Fe, Co, Ni, Cu, Zn, Au, Pd, Pt, and In.

[0010] The embodiment of the present invention also provides alloyed fluorescent quantum dots prepared by the aforementioned method, and the fluorescence emission peak wavelength of the alloyed fluorescent quantum dots is between 500 and 1700 nm.

[0011] Furthermore, the absolute quantum efficiency of the alloyed fluorescent quantum dots is greater than 85%.

[0012] Furthermore, the alloyed fluorescent quantum dots include AgAuSe, CuAgS, AgInTe 2 Any one or a combination of two or more.

[0013] Furthermore, the alloyed fluorescent quantum dots include doped alloyed fluorescent quantum dots.

[0014] Furthermore, the alloyed fluorescent quantum dots have a core-shell structure.

[0015] The embodiments of the present invention also provide the use of any of the aforementioned alloyed fluorescent quantum dots in the fields of biological imaging, biomedicine or near-infrared devices (such as near-infrared light-emitting diodes).

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1) The present invention first prepares silver quantum dots by a simple high-temperature solvent thermal method, and then obtains alloyed quantum dots by an ion exchange method. The synthesis process is simple, the experimental conditions are controllable, and the reagents used are simple and easy to obtain. The final product yield is high and suitable for large-scale production;

[0018] 2) The final product alloyed fluorescent quantum dots prepared by the present invention have uniform size distribution, and the fluorescence emission is adjustable from visible light to near infrared, and has excellent photostability, and does not contain any toxic heavy metal elements, and has broad application prospects in the fields of biological imaging, near infrared devices, etc.;

[0019] 3) The preparation process of the present invention can also be extended to the preparation process of other fluorescent quantum dots, and has a high yield and is easy to scale up the reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the invention herein. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 is a transmission electron microscope photograph of the alloyed fluorescent quantum dots prepared in Example 1 of the present invention;

[0022] Figure 2 is a visible-near infrared absorption spectrum of the alloyed fluorescent quantum dots prepared in Example 1 of the present invention;

[0023] Figure 3is the fluorescence emission spectrum of the alloyed fluorescent quantum dots prepared in Example 1 of the present invention;

[0024] Figure 4 This is a quantum efficiency measurement spectrum of the alloyed fluorescent quantum dots prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0025] As mentioned above, given that the existing fluorescent quantum dots, such as lead sulfide, cadmium telluride, lead selenide, mercury telluride, silver selenide, etc., have low absolute fluorescence quantum yields, and some contain toxic heavy metal elements, it is difficult to achieve both fluorescence intensity and toxicity. After long-term research and extensive practice, the inventors of this case found that the alloyed quantum dots after ion exchange of some elements with silver-based quantum dots have good optical properties. The technical solution of the present invention will be explained in more detail below.

[0026] As one aspect of the technical solution of the present invention, it involves a method for preparing alloyed fluorescent quantum dots, which comprises:

[0027] A first uniformly mixed reaction system including a silver source, an anion source, and a weakly polar solvent is subjected to a solvothermal reaction to obtain a silver-based quantum dot precursor;

[0028] The second uniformly mixed reaction system including the silver-based quantum dot precursor, the anion source and / or the metal cation source is subjected to an ion exchange reaction at 0 to 260° C. for 0.4 to 72 hours to obtain alloyed fluorescent quantum dots.

[0029] In some embodiments, the silver source includes a silver salt, and the silver salt includes any one or a combination of two or more of silver chloride, silver bromide, silver iodide, silver sulfate, silver nitrate, silver carbonate, silver acetate, silver sulfide, silver trifluoroacetate, silver diethyldithiocarbamate, etc., but is not limited thereto.

[0030] In some embodiments, the anion source includes any one or a combination of two or more of a sulfur source, a selenium source, and a tellurium source, but is not limited thereto.

[0031] Furthermore, the sulfur source includes any one or a combination of two or more of sulfur, sodium thiosulfate, sodium sulfide, thiourea, etc., but is not limited thereto.

[0032] Furthermore, the selenium source includes any one or a combination of two or more of selenium dioxide, selenium, sodium selenate, sodium selenite, sodium selenide, diphenyl diselenide, etc., but is not limited thereto.

[0033] Furthermore, the tellurium source includes any one of tellurium, sodium tellurate, sodium hydride telluride, etc., or a combination of two or more thereof, but is not limited thereto.

[0034] Further, the weak polar solvent includes any one or a combination of two or more of oleylamine, oleic acid, octadecene, octadecylamine, dodecylamine, tetradecylamine, dodecanethiol, octadecylmercaptan, octadecylmercaptan, etc., but is not limited thereto.

[0035] In some embodiments, the mass ratio of the silver source to the anion source is 1-10:1-10.

[0036] In some embodiments, the solvothermal reaction is carried out at a temperature of 100 to 300° C. and for a time of 0.5 to 24 hours.

[0037] In some preferred embodiments, the silver-based quantum dot precursor may be Ag 2 S, Ag 2 Se, Ag 2 Any one or a combination of two or more of Te, etc., but not limited thereto.

[0038] Furthermore, in a more typical embodiment, the preparation method may include: first dissolving silver nitrate in oleylamine, adding a sulfur source, reacting at 200° C. for 1 to 6 hours, and then washing to obtain the target product, a silver-based quantum dot precursor.

[0039] In some preferred embodiments, the preparation method may include: dissolving 0.1-1 g of silver salt in a weak polar solvent.

[0040] Furthermore, the preparation method specifically includes: mixing the silver sulfide precursor with a gold source, reacting at 100° C., and obtaining silver-gold-sulfur fluorescent quantum dots.

[0041] Furthermore, the preparation method further comprises: after the reaction is completed, cleaning the obtained silver-gold-sulfur fluorescent quantum dots.

[0042] In some embodiments, the mass ratio of the silver-based quantum dot precursor to the metal cation source is 1-10:1-10.

[0043] In some preferred embodiments, the metal elements contained in the metal cation source may include any one or a combination of two or more of Mn, Fe, Co, Ni, Cu, Zn, Au, Pd, Pt, In, etc., but is not limited thereto.

[0044] Further, the metal cation source can include any one or a combination of two or more of ferric chloride, ferrous chloride, ferrous sulfate, ferrous sulfate, ferric nitrate, cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt acetate, nickel chloride, nickel nitrate, nickel sulfate, nickel acetate, copper sulfate, copper acetate, copper nitrate, cupric chloride, cuprous chloride, zinc acetate, zinc nitrate, zinc sulfate, zinc chloride, sodium chloroaurate, chloroauric acid, gold nitrate, gold chloride, gold hydroxide, gold oxide, palladium acetate, palladium nitrate, palladium chloride, chloroplatinic acid, sodium chloroplatinate, potassium chloroplatinate, indium acetate, indium chloride, etc., but is not limited thereto.

[0045] The aforementioned silver salt, anion source, weak polar solvent and metal cation source can be selected from but not limited to the types listed above.

[0046] In some embodiments, the preparation method specifically comprises:

[0047] A silver source and a weakly polar solvent are uniformly mixed and an anion source is added to perform a solvothermal reaction to obtain a silver-based quantum dot precursor (also referred to as a "silver-based quantum dot precursor");

[0048] The silver series quantum dot precursor is mixed with a metal cation source at 0-260° C. to react, thereby obtaining alloyed fluorescent quantum dots, the fluorescence emission peak wavelength of which is between 500 and 1700 nm.

[0049] Wherein, when the metal cation source is a gold source and the anion source is a sulfur source, as one of the more specific implementation schemes, the preparation method of the alloyed fluorescent quantum dots may include the following steps:

[0050] I. Mixing silver salt with a weakly polar solvent and uniformly dispersing by ultrasonication;

[0051] II. Add a sulfur source to the mixed solution obtained in step I, mix and disperse evenly, and then react at 100-300° C. for 0.5-24 hours;

[0052] III. Separating the product obtained by the solvothermal reaction in step II, and washing and drying it;

[0053] IV. React the product obtained in step III with a gold source at 0-200° C. for 10-72 h to obtain near-infrared silver-gold-sulfur fluorescent quantum dots.

[0054] The alloyed fluorescent quantum dots prepared by the present invention have uniform size distribution, and the peak wavelength of fluorescence emission is between 500 and 1700 nm, preferably between 800 and 1100 nm, and have ultra-high absolute fluorescence quantum efficiency (greater than 85%), and do not contain any toxic heavy metal elements. The final product yield is high, and the preparation process is easy to scale up the reaction.

[0055] As another aspect of the technical solution of the present invention, it also relates to alloyed fluorescent quantum dots prepared by the aforementioned method, which have uniform morphology and size, high absolute quantum yield, and do not contain any toxic heavy metal elements, and have important application prospects in the fields of biological imaging, biomedicine or near-infrared devices.

[0056] Furthermore, the alloyed fluorescent quantum dots may preferably include AgAuS, CuAgSe, AgInTe 2 Any one or a combination of two or more thereof, but not limited thereto.

[0057] Further, the alloyed fluorescent quantum dots include doped alloyed fluorescent quantum dots; for example, preferably may include any one or a combination of two or more of manganese-doped silver selenide fluorescent quantum dots, nickel-doped silver telluride fluorescent quantum dots, indium-doped silver sulfide fluorescent quantum dots, cobalt-doped silver sulfide fluorescent quantum dots, etc., but is not limited thereto.

[0058] Further, the alloyed fluorescent quantum dots have a core-shell structure; for example, the alloyed fluorescent quantum dots may preferably include Ag 2 S@ZnS、Ag 2 Te@Ag 2 S, Ag 2 Se@Ag 2 S, Ag 2 Se@ZnS、Ag 2 Se@ZnSe、Ag 2 Any one or a combination of two or more of S@MnS, etc., but not limited thereto.

[0059] Another aspect of the embodiments of the present invention further provides the use of any of the aforementioned alloyed fluorescent quantum dots in the fields of biological imaging, biomedicine or near-infrared devices.

[0060] Furthermore, the near-infrared device may be a near-infrared light emitting diode, but is not limited thereto.

[0061] In summary, through the aforementioned technical scheme, the present invention first prepares silver quantum dots by a simple high-temperature solvent thermal method, and then obtains alloyed quantum dots by an ion exchange method. The synthesis process is simple and controllable, and the yield is high. It can be prepared on a large scale, and the fluorescence emission is adjustable from visible light to near infrared, and has excellent photostability. At the same time, it does not contain any toxic heavy metal elements, and has broad application prospects in the fields of biological imaging, near-infrared devices, etc.

[0062] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention is further described in detail below in conjunction with several preferred embodiments, but the present invention is not limited to the following embodiments, and the non-essential improvements and adjustments made by technicians in this field under the core guiding ideology of the present invention still belong to the protection scope of the present invention. Unless otherwise specified, the various reagents used in the following examples are well known to those skilled in the art and can be obtained through channels such as commercial purchase. The experimental methods in the following examples that do not specify specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0063] Example 1

[0064] Dissolve 0.06 g of silver nitrate in 20 mL of oleylamine and disperse it evenly by ultrasonication. Then add 0.06 g of sulfur powder and react at 200 °C for 5 h to obtain a silver sulfide precursor. Then add 0.06 g of chloroauric acid and react at 100 °C for 48 h to obtain silver-gold-sulfur fluorescent quantum dots.

[0065] As can be seen from FIG. 1 , the near-infrared silver-gold-sulfur fluorescent quantum dot product obtained in this example has a uniform morphology and size, and a size of about 4.5 nm.

[0066] The silver-gold-sulfur quantum dots are dispersed in chloroform. The absorption spectrum is measured using a visible-near infrared absorption spectrometer. It can be seen that the quantum dots have strong absorption in the visible to near infrared region, such as Figure 2 As shown. The luminescence spectrum and absolute fluorescence quantum yield were further tested using a near-infrared fluorescence spectrometer. Figure 3 It can be seen that the emission of the silver-gold-sulfur fluorescent quantum dots is located at 800-1100nm. Figure 4 It can be seen that its absolute quantum efficiency is 85.15%.

[0067] Example 2

[0068] Dissolve 0.06 g of silver acetate in 20 mL of oleic acid and disperse it evenly by ultrasonication. Then add 0.6 g of sulfur powder and react at 250 °C for 0.5 h to obtain a silver sulfide precursor. Then add 0.6 g of cuprous chloride and react at 200 °C for 10 h to obtain silver-copper-sulfur fluorescent quantum dots.

[0069] Example 3

[0070] Dissolve 0.6 g of silver nitrate in 20 mL of octadecyl mercaptan and disperse it evenly by ultrasonication. Then add 0.6 g of tellurium powder and react at 150 °C for 5 h to obtain a silver telluride precursor. Then add 0.6 g of selenium powder and react at 100 °C for 24 h to obtain silver selenium telluride fluorescent quantum dots.

[0071] Example 4

[0072] Dissolve 0.06 g of silver trifluoroacetate in 20 mL of dodecylamine and disperse it evenly by ultrasonication. Then add 0.06 g of selenium powder and react at 180 °C for 10 h to obtain a silver selenide precursor. Then add 0.06 g of chloroplatinic acid and react at 0 °C for 72 h to obtain silver-platinum-selenium fluorescent quantum dots.

[0073] Example 5

[0074] Dissolve 0.06 g of silver chloride in 20 mL of octanethiol and disperse it evenly by ultrasonication. Then add 0.6 sulfur powder and react at 200 °C for 12 h to obtain a silver sulfide precursor. Then add 0.06 g of ferrous chloride and react at 0 °C for 72 h to obtain silver-iron-selenium fluorescent quantum dots.

[0075] Example 6

[0076] Dissolve 0.6 g of silver sulfide in 20 mL of hexadecylamine and disperse it evenly by ultrasonication. Then add 0.06 g of selenium powder and react at 200 °C for 5 h to obtain a silver selenide precursor. Then add 0.06 g of palladium chloride and react at 0 °C for 72 h to obtain palladium silver selenium fluorescent quantum dots.

[0077] Example 7

[0078] Dissolve 0.06 g of silver iodide in 20 mL of oleylamine and disperse it evenly with ultrasound. Then add 0.06 g of selenium powder and react at 200 °C for 5 h to obtain a silver selenide precursor. Then add 0.06 g of manganese chloride and react at 0 °C for 72 h to obtain manganese-doped silver selenide fluorescent quantum dots.

[0079] Example 8

[0080] 0.06 g of silver acetate was dissolved in 20 mL of oleylamine and dispersed evenly by ultrasonication. Then 0.06 g of selenium powder was added and reacted at 300 °C for 0.5 h to obtain a silver selenide precursor. Then 0.06 g of sulfur powder was added and reacted at 100 °C for 72 h to obtain Ag. 2 Se@Ag 2 S fluorescent quantum dots.

[0081] Example 9

[0082] 0.6 g of silver sulfate was dissolved in 20 mL of octadecyl mercaptan and dispersed evenly by ultrasonication. Then 0.06 g of tellurium powder was added and reacted at 150 ° C for 1 h to obtain a silver telluride precursor. Then 0.6 g of sulfur powder and 0.06 g of zinc acetate were added and reacted at 260 ° C for 0.4 h to obtain Ag. 2 Te@ZnS fluorescent quantum dots.

[0083] Example 10

[0084] 0.5 g of silver diethyldithiocarbamate was dissolved in 20 mL of octadecyl mercaptan and dispersed evenly by ultrasonication. Then 0.06 g of tellurium powder was added and reacted at 200 °C for 1 h to obtain a silver telluride precursor. Then 0.06 g of nickel acetate was added and reacted at 150 °C for 2 h to obtain nickel-doped silver telluride fluorescent quantum dots.

[0085] Embodiment 11

[0086] 0.04 g of silver acetate was dissolved in 20 mL of dodecanethiol and dispersed evenly by ultrasonication. Then, 0.06 g of sulfur powder was added and reacted at 200 °C for 1 h to obtain a silver sulfide precursor. Then, 0.06 g of indium acetate was added and reacted at 150 °C for 2 h to obtain indium-doped silver sulfide fluorescent quantum dots.

[0087] Example 12

[0088] 0.06 g of silver carbonate was dissolved in 20 mL of dodecanethiol and dispersed evenly by ultrasonication. Then, 0.06 g of sulfur powder was added and reacted at 100 °C for 24 h to obtain a silver sulfide precursor. Then, 0.06 g of cobalt chloride was added and reacted at 100 °C for 48 h to obtain cobalt-doped silver sulfide fluorescent quantum dots.

[0089] In addition, the inventors of this case also used other raw materials and other process conditions listed above to replace the various raw materials and corresponding process conditions in Examples 1-12 to conduct corresponding experiments. The morphology and performance of the alloyed fluorescent quantum dots obtained were also relatively ideal, basically similar to the products of Examples 1-12.

[0090] The present invention first prepares silver quantum dots by a simple high-temperature solvent thermal method, and then obtains alloyed quantum dots by an ion exchange method. The synthesis process is simple and controllable, and the yield is high. It can be prepared on a large scale, and the fluorescence emission is adjustable from visible light to near infrared, and has excellent photostability. At the same time, it does not contain any toxic heavy metal elements, and has broad application prospects in the fields of biological imaging, near-infrared devices, etc.

[0091] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing alloyed fluorescent quantum dots, Features include: A first uniformly mixed reaction system comprising a silver source, an anion source, and a weakly polar solvent is subjected to a solvothermal reaction to obtain a silver-based quantum dot precursor, wherein the anion source is a sulfur source, the sulfur source is sulfur, the mass ratio of the silver source to the anion source is 1-10:1-10, the weakly polar solvent is selected from any one of oleylamine, oleic acid, octadecene, octadecylamine, dodecylamine, tetradecylamine, dodecyl mercaptan, octadecyl mercaptan, and octadecyl mercaptan, or a combination of two or more thereof, the solvothermal reaction temperature is 200°C, the time is 1-6 h, and the silver-based quantum dot precursor is Ag. 2 S; A second uniformly mixed reaction system comprising a silver-based quantum dot precursor and a metal cation source is subjected to an ion exchange reaction at 100° C. for 0.4 to 72 h to obtain alloyed fluorescent quantum dots, wherein the mass ratio of the silver-based quantum dot precursor to the metal cation source is 1 to 10:1 to 10; and the metal element contained in the metal cation source is Au; The fluorescence emission peak wavelength of the alloyed fluorescent quantum dots is between 500 and 1700 nm, and the absolute quantum efficiency of the alloyed fluorescent quantum dots is greater than 85%.

2. The preparation method according to claim 1, Features: The silver source comprises a silver salt, and the silver salt is selected from any one or a combination of two or more of silver chloride, silver bromide, silver iodide, silver sulfate, silver nitrate, silver carbonate, silver acetate, silver sulfide, silver trifluoroacetate, and silver diethyldithiocarbamate.

3. The preparation method according to claim 1, Features: The metal cation source is selected from any one or a combination of two or more of sodium chloroaurate, chloroauric acid, gold nitrate, gold chloride, gold hydroxide, and gold oxide.

4. The alloyed fluorescent quantum dots prepared by the preparation method according to any one of claims 1 to 3, wherein the fluorescence emission peak wavelength is between 500 and 1700 nm, the absolute quantum efficiency of the alloyed fluorescent quantum dots is greater than 85%, and the alloyed fluorescent quantum dots are AgAuS.

5. The alloyed fluorescent quantum dots according to claim 4, Features: The peak wavelength of fluorescence emission of the alloyed fluorescent quantum dots is 800-1100 nm.

6. Use of the alloyed fluorescent quantum dots according to any one of claims 4 to 5 in the field of near-infrared devices.

7. The use according to claim 6, Features: The near infrared device is a near infrared light emitting diode.

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