CN112625672A - Particle size controllable nontoxic quantum dot and preparation method thereof - Google Patents

Abstract

The invention discloses a non-toxic quantum dot with controllable particle size and a preparation method thereof. The preparation method of the nontoxic quantum dot comprises the steps of preparing a core structure and a shell structure; the core structure is indium phosphide, wherein the donor of indium is indium halide, and the donor of phosphorus is tris (diethylamino) phosphorus; the shell structure is zinc sulfide, wherein the zinc donor is zinc halide, and the sulfur donor is trioctylthio. The invention adopts the tris (diethylamino) phosphorus, avoids the generation of toxic gas and reduces the production cost. And secondly, the method can also effectively control the wavelength and the particle size of the quantum dots, and the particle size of the QDs is controlled by adopting different compositions and proportions of halogen elements, so that the instability and the certainty of controlling the particle size of the QDs by controlling the synthesis time in the conventional QDs synthesis method are changed, and the controllability of the method is increased.

Description

Particle size controllable nontoxic quantum dot and preparation method thereof

Technical Field

The invention relates to a particle size controllable nontoxic quantum dot and a preparation method thereof, belonging to the technical field of fine chemical engineering.

Background

After more than thirty years of development, Quantum dot materials (QDs) play an important role in basic research and industrial production, and the high-performance photoluminescence effect thereof has wide application in the fields of luminescent devices, display devices, light detection devices, chemical and biological fluorescent probes and the like. At present, the morphology, size, components and surface ligands of QDs can be strictly controlled, and the QDs play an increasingly important role in a fluorescent material-based small molecule rapid immunoassay method. However, QDs still have many limitations in practical applications. Traditional high performance QDs materials (II-VI or IV-VI families) usually contain highly toxic elements such as cadmium or lead, and the preparation and use of such materials in large quantities not only causes great harm to human bodies, but also causes environmental and ecological problems. Therefore, the design and development of low-toxicity and high-performance QDs are one of the leading lines of research. The toxicity of III-V semiconductor materials (representative materials are indium phosphide) is far less than that of II-VI and IV-VI materials, and the III-V semiconductor materials are one of the main materials for synthesizing high-performance non-toxic quantum dots at present. In addition, in order to obtain QDs of different colors, the synthesis time and temperature must be strictly controlled, which is very demanding for experimental operations and is not suitable for popularization of the preparation method, and thus, it is necessary to improve the existing preparation method.

Disclosure of Invention

The invention aims to provide a non-toxic quantum dot with controllable particle size and a preparation method thereof, which avoid the use of toxic elements, reduce the harm to human health and environment, simultaneously realize simple controllability of different QDs emission wavelengths and particle sizes, and improve the operability in quantum dot synthesis.

The preparation method of the non-toxic quantum dot with the controllable particle size comprises the steps of preparing a core structure and a shell structure;

the core structure is indium phosphide, wherein the indium donor can be indium halide;

the shell structure is zinc sulfide, wherein the zinc donor can be a zinc halide.

In the above preparation method, the donor of phosphorus in the indium phosphide may be tris (diethylamino) phosphorus.

In the preparation method, the donor of sulfur in the zinc sulfide is trioctylthio.

In the above preparation method, the indium halide is indium fluoride, indium chloride or indium bromide;

the zinc halide is zinc fluoride, zinc chloride or zinc bromide.

In the above preparation method, the core structure is prepared by the following steps:

under the inert atmosphere and vacuum condition, carrying out nucleation reaction on the indium halide and the donor of phosphorus in the nuclear structure to obtain the indium-doped zinc oxide material;

the temperature of the nucleation reaction is 180-250 ℃, and the time is 8-12 min.

In the above preparation method, the steps of preparing the shell structure are as follows:

under the conditions of inert atmosphere and vacuum, in the system after the core structure reaction, the zinc halide and the donor of sulfur in the shell structure are reacted to obtain the zinc halide;

the reaction temperature is 300-350 ℃, and the reaction time is 10-20 min.

In the above production method, the conditions of the nucleation reaction are any one of the following 1) to 4):

1) the donor of indium is indium chloride, the donor of zinc is zinc bromide, and the mass ratio of indium chloride to zinc bromide is 0.05: 1, the temperature of the nucleation reaction is 180-220 ℃, the time is 8-12 min, and under the condition, the blue-green quantum dots with the smallest particle size are obtained;

2) the donor of the indium is indium bromide, the donor of the zinc is zinc bromide, and the mass ratio of the indium bromide to the zinc bromide is 0.08: 1, the temperature of the nucleation reaction is 180-220 ℃, the time is 8-12 min, and under the condition, the green quantum dots with larger particle size are obtained;

3) the indium donor is indium chloride, the zinc donor is zinc chloride, and the mass ratio of the indium chloride to the zinc chloride is 1: at 15.4, the temperature of the nucleation reaction is 220-250 ℃, the time is 8-12 min, and under the condition, orange quantum dots with larger particle sizes are obtained;

4) the indium donor is indium fluoride, the zinc donor is zinc chloride, and the mass ratio of the indium fluoride to the zinc chloride is 1: and 4, the temperature of the nucleation reaction is 220-250 ℃, the time is 8-12 min, and the orange quantum dots with larger particle sizes are obtained under the condition.

In the preparation method, the method further comprises the steps of carrying out sulfhydrylation modification and hydrophilization treatment on the nontoxic quantum dots in sequence;

specifically, 1-dodecyl mercaptan is adopted for carrying out the sulfhydrylation modification;

the volume ratio of the nontoxic quantum dots to the 1-dodecanethiol can be 1: 1-5, specifically 1: 2.5;

the number of times of sulfhydrylation modification is 1-3;

the reaction time of each sulfhydrylation modification can be 5-15 min, specifically 10min, and the reaction temperature can be 20-30 ℃, specifically 25 ℃.

Specifically, the hydrophilization treatment is carried out by a reverse microemulsion liquefaction method;

the conditions of the hydrophilization treatment are as follows:

the volume ratio of the adopted reverse microemulsion is 30-70: 5-20: 1 of heptane, a surfactant Brij30 and ammonia water, wherein the volume concentration of the ammonia water is 3%;

the hydrophilizing agent is tetraethoxysilane, and the volume ratio of tetraethoxysilane to the ammonia water is 1: 3-9, specifically 1: 6.

the method can prepare the indium phosphide/zinc sulfide core-shell structure QDs with different colors and particle sizes, such as blue-green quantum dots with the smallest particle size, green quantum dots with larger particle size, orange quantum dots with larger particle size and orange quantum dots with larger particle size.

Because the existing quantum dot synthesis method mostly uses raw materials containing heavy metal elements such as cadmium and the like, the environmental pollution is great, and the human health can be influenced. The method changes the raw materials for quantum dot synthesis, uses III and V semiconductor materials as the material donor of the core; in addition, donors of phosphorus elements such as tris (trimethylsilyl) phosphine, phosphine and the like are often used in the synthesis of the indium phosphide quantum dots, and toxic phosphine gas is easily generated in the synthesis process. And secondly, the method can also effectively control the wavelength and the particle size of the quantum dots, and the particle size of the QDs is controlled by adopting different compositions and proportions of halogen elements, so that the instability and the certainty of controlling the particle size of the QDs by controlling the synthesis time in the conventional QDs synthesis method are changed, and the controllability of the method is increased.

Drawings

FIG. 1 is a synthetic route of non-toxic quantum dots with controllable particle size provided by the invention.

Fig. 2 is a fluorescent picture of the particle size controllable non-toxic quantum dots prepared in examples 1-4 of the present invention under an ultraviolet lamp.

Fig. 3 is an emission spectrum of non-toxic quantum dots with controllable particle sizes prepared in examples 1-4 of the present invention.

FIG. 4 shows the distribution of quantum dots in an aqueous solution before and after adding dodecanethiol when quantum modification is performed in example 5 of the present invention.

Detailed Description

The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The flow chart of the preparation method of the non-toxic quantum dot with controllable particle size provided by the invention is shown in figure 1, and mainly comprises the following steps: the method comprises the steps of synthesis of an indium phosphide core structure in controllable non-toxic indium phosphide/zinc sulfide, synthesis of a shell, modification of sulfhydrylation and hydrophilic treatment. Compared with the traditional quantum dot synthesis method, the method which is most commonly adopted controls the particle size and the wavelength by controlling the time of nuclear reaction, and the invention changes the composition of halogen elements in the nuclear material to change the particle size, so that the reaction method is simple, flexible and controllable, and easy to realize large-scale production.

Example 1: synthesis of indium phosphide/zinc sulfide of nontoxic blue-green quantum dot

Adding 50mg of indium chloride and 1g of zinc bromide into a three-hole flask, then taking 5mL of oleylamine out of a vacuum glove box, injecting quickly, closing the three-hole flask after the oleylamine is injected, vacuumizing for 30min, and setting the temperature to be 120 ℃; and (3) closing the vacuum, starting introducing nitrogen, heating to 200 ℃, adding 0.2mL of tris (diethylamino) phosphorus solution to gradually turn yellow, continuously heating for 10min, and extracting a small amount of sample at any time in the heating process to detect, namely the core structure of the required blue-green quantum dot. Then, dropwise adding 1.7mL of trioctylthio, gradually changing the reaction system to orange, and then continuously heating to 320 ℃; sampling and detecting at any time, and stopping heating after 20min, so that the required shell structure of the zinc sulfide is obtained. And (2) reducing the temperature of the reactant to 80 ℃, adding toluene with one volume, transferring the solution into a glass centrifuge tube, centrifuging at 3800rpm for 10min, taking the supernatant, quickly adding a large amount of acetone to ensure that the solution is completely changed into a green foam, centrifuging at 3800rpm for 10min, discarding the supernatant, adding toluene with about 5mL of the remained precipitate for dissolving, performing ultrasonic treatment, and finally preparing the quantum dot with the required blue-green color.

EXAMPLE 2 Synthesis of indium phosphide/zinc sulfide of non-toxic Green Quantum dots

Adding 80mg of indium bromide and 1g of zinc bromide into a three-hole flask, then taking 5mL of oleylamine out of a vacuum glove box, injecting quickly, sealing the three-hole flask after the oleylamine is injected, vacuumizing for 30min, and setting the temperature to be 120 ℃; and (3) closing the vacuum, starting introducing nitrogen, heating to 200 ℃, adding 0.28mL of tris (diethylamino) phosphorus solution to gradually turn yellow, continuously heating for 10min, and extracting a small amount of samples at any time in the heating process to detect, namely the core structure of the required green quantum dot. Then, dropwise adding 1.8mL of trioctylthio, gradually changing the reaction system to orange, and then continuously heating to 320 ℃; sampling and detecting at any time, and stopping heating after 20min, so that the required shell structure of the zinc sulfide is obtained. Reducing the temperature of reactants to 80 ℃, adding toluene with one volume, transferring the solution into a glass centrifuge tube, centrifuging at 3800rpm for 10min, taking the supernatant, rapidly adding a large amount of acetone to ensure that the solution is completely changed into a green foam, centrifuging at 3800rpm for 10min, discarding the supernatant, adding toluene with about 5mL of the remaining precipitate for dissolving, performing ultrasonic treatment, and finally preparing the required green quantum dots.

EXAMPLE 3 Synthesis of indium phosphide/zinc sulfide of non-toxic orange Quantum dots

Adding 50mg of indium chloride and 770mg of zinc chloride into a three-hole flask, then taking 5mL of oleylamine out of a vacuum glove box, injecting quickly, closing the three-hole flask after finishing injection, starting vacuumizing for 30min, and setting the temperature to be 120 ℃; and (3) closing the vacuum, starting introducing nitrogen, heating to 240 ℃, adding 0.1mL of tris (diethylamino) phosphorus, heating to 270 ℃ for 3min, slowly adding 0.15mL of tris (diethylamino) phosphorus solution, gradually changing into yellow, and maintaining for 10min to obtain the core structure of the orange indium phosphide quantum dot. Then, the temperature was raised to 320 ℃ and 2mL of trioctylthio was added (during the temperature raising) and added slowly. And (3) taking a small amount of samples at any time for detection, and continuously heating for 10min to obtain the required zinc sulfide shell structure of the orange quantum dots. And (2) reducing the temperature of the reactant to 80 ℃, adding toluene with one volume, transferring the solution into a glass centrifuge tube, centrifuging at 3800rpm for 10min, taking the supernatant, quickly adding a large amount of acetone to ensure that the solution is completely changed into a green foam, centrifuging at 3800rpm for 10min, discarding the supernatant, adding toluene with about 5mL of the remained precipitate for dissolving, and carrying out ultrasonic treatment to finally prepare the required orange quantum dot.

EXAMPLE 4 Synthesis of indium phosphide/zinc sulfide of non-toxic Red Quantum dots

Adding 77mg of indium fluoride and 300mg of zinc chloride into a three-hole flask, then taking 5mL of oleylamine out of a vacuum glove box, injecting quickly, closing the three-hole flask after the completion of the oleylamine is injected, vacuumizing for 30min, and setting the temperature to be 120 ℃; and (3) closing the vacuum, starting introducing nitrogen, heating to 240 ℃, adding 0.45mL of tris (diethylamino) phosphorus, gradually turning the solution into black, and maintaining for 10min to obtain the core structure of the red indium phosphide quantum dot. Then 1mL of trioctylthio was added dropwise, slowly added, and the temperature was raised to 320 ℃. And (3) taking a small amount of samples at any time for detection, and continuously heating for 10min to obtain the required zinc sulfide shell structure of the red quantum dots. Reducing the temperature of reactants to 80 ℃, adding toluene with one volume, transferring the solution into a glass centrifuge tube, centrifuging at 3800rpm for 10min, taking the supernatant, rapidly adding a large amount of acetone to ensure that the solution is completely changed into a green foam, centrifuging at 3800rpm for 10min, discarding the supernatant, adding toluene with about 5mL of the remaining precipitate for dissolving, performing ultrasonic treatment, and finally preparing the required red quantum dot.

The colors of the non-toxic quantum dots prepared in examples 1 to 4 under an ultraviolet lamp are shown in fig. 2, and are respectively blue-green, orange and red, and the emission spectra are shown in fig. 3, and it can be seen from the graph that the emission wavelengths of the quantum dots with four different colors obtained by the present invention are 490nm, 520nm, 590nm and 650nm, respectively.

Examples 5,

In order to improve the stability of the quantum dot after hydrophilic modification, in this example, the prepared quantum dot is subjected to thiol modification, and then subjected to hydrophilic treatment, so that the particle size of the quantum dot in an aqueous solution is smaller, the dispersion is more uniform, and the quantum dot is beneficial to long-time storage, and the specific steps are as follows:

0.2mL of the quantum dot prepared in example 1 was added with 0.5mL of 1-dodecanethiol, stirred for 10min, added with 1mL of ethanol, the solution was transferred to a glass centrifuge tube and centrifuged at 3800rpm for 10min, the supernatant was discarded, the precipitate was dissolved in about 0.5mL of toluene, 0.5mL of 1-dodecanethiol was added again, the above operation was repeated three times, and the finally obtained quantum dot was dissolved in 0.2mL of toluene and used for the next hydrophilization treatment of the quantum dot.

About 10nmol of the quantum dots prepared above were put into two clean glass vials, put into a small rotor, added with 2mL heptane, stirred gently, added with Brij30, 0.64mL, stirred for 10min, added with 120 μ l of 3% ammonia water, and reacted for 1 hour in the dark. 0.02mL of tetraethoxysilane was added in one portion and reacted for 48 h. Adding 2mL of ethanol into each solution per minute, centrifuging at 4500rpm for 5min until the quantum dots are completely precipitated, discarding the supernatant, drying absorbent paper, adding 10mL of n-hexane into each solution, whirling, ultrasonically dispersing completely, centrifuging at 4500rpm, adding 10mL of ethanol, washing twice, adding 5mL of deionized water, discarding the supernatant, adding 1mL of deionized water, repeating the steps twice, and finally re-dissolving the precipitate by using 5mL of milliQ water with the pH value of 7.4 to obtain the quantum dots for hydrophilization.

In this example, after the quantum dots are modified by adding dodecanethiol, it is found that the quantum dots are clearer and more transparent in an aqueous solution than an aqueous solution of quantum dots without dodecanethiol modification, which indicates that the quantum dots modified by dodecanethiol have smaller particle size and are more uniformly distributed, as shown in fig. 4.

The embodiments show that the method can prepare the non-toxic quantum dots with the controllable particle size and wavelength, and the quantum dots with the indium phosphide/zinc sulfide core-shell structure can be used for modification of biological molecules and the like.

Claims (10)

1. A method for preparing non-toxic quantum dots with controllable particle size comprises the steps of preparing a core structure and a shell structure;

the core structure is indium phosphide, wherein the indium donor is indium halide;

the shell structure is zinc sulfide, wherein the zinc donor is zinc halide.

2. The method of claim 1, wherein: the donor of phosphorus in the indium phosphide is tris (diethylamino) phosphorus.

3. The production method according to claim 1 or 2, characterized in that: the donor of sulfur in the zinc sulfide is trioctylthio.

4. The production method according to any one of claims 1 to 3, characterized in that: the indium halide is indium fluoride, indium chloride or indium bromide;

the zinc halide is zinc fluoride, zinc chloride or zinc bromide.

5. The production method according to any one of claims 1 to 4, characterized in that: the steps for preparing the core structure are as follows:

under the inert atmosphere and vacuum condition, carrying out nucleation reaction on the indium halide and the donor of phosphorus in the nuclear structure to obtain the indium-doped zinc oxide material;

the temperature of the nucleation reaction is 180-250 ℃, and the time is 8-12 min.

6. The production method according to any one of claims 1 to 5, characterized in that: the steps for preparing the shell structure are as follows:

under the conditions of inert atmosphere and vacuum, in the system after the core structure reaction, the zinc halide and the donor of sulfur in the shell structure are reacted to obtain the zinc halide;

the reaction temperature is 300-350 ℃, and the reaction time is 10-20 min.

7. The production method according to claim 5 or 6, characterized in that: the condition of the nucleation reaction is any one of the following 1) to 4):

1) the donor of indium is indium chloride, the donor of zinc is zinc bromide, and the mass ratio of indium chloride to zinc bromide is 0.05: 1 (in the moment, the temperature of the nucleation reaction is 180-220 ℃, and the time is 8-12 min;

2) the donor of the indium is indium bromide, the donor of the zinc is zinc bromide, and the mass ratio of the indium bromide to the zinc bromide is 0.08: 1, the temperature of the nucleation reaction is 180-220 ℃, and the time is 8-12 min;

3) the indium donor is indium chloride, the zinc donor is zinc chloride, and the mass ratio of the indium chloride to the zinc chloride is 1: at 15.4, the temperature of the nucleation reaction is 220-250 ℃, and the time is 8-12 min;

4) the indium donor is indium fluoride, the zinc donor is zinc chloride, and the mass ratio of the indium fluoride to the zinc chloride is 1: and 4, the temperature of the nucleation reaction is 220-250 ℃, and the time is 8-12 min.

8. The production method according to any one of claims 1 to 7, characterized in that: the method also comprises the step of carrying out sulfhydrylation modification and hydrophilization treatment on the nontoxic quantum dots in sequence.

9. The method of claim 8, wherein: carrying out the sulfhydrylation modification by using 1-dodecyl mercaptan;

the volume ratio of the nontoxic quantum dots to the 1-dodecanethiol is 1: 1-5;

the number of times of sulfhydrylation modification is 1-3;

the reaction time of each sulfhydrylation modification is 5-15 min, and the reaction temperature is 20-30 ℃;

carrying out hydrophilization treatment by adopting a reverse microemulsion liquefaction method;

the conditions of the hydrophilization treatment are as follows:

the volume ratio of the adopted reverse microemulsion is 30-70: 5-20: 1 of heptane, a surfactant Brij30 and ammonia water, wherein the volume concentration of the ammonia water is 3%;

the hydrophilizing agent is tetraethoxysilane, and the volume ratio of tetraethoxysilane to the ammonia water is 1: 3 to 9.

10. Non-toxic quantum dots of controlled particle size prepared by the method of any one of claims 1 to 9.

Images