Novel preparation method of Mn < 2 + > doped I-III-VI group derivative quantum dots

Abstract

The invention discloses a novel preparation method for doping I-III-VI derived quantum dots by using metal manganese divalent ions (Mn < 2 + >). According to the method, in an inert gas environment, under the condition that sulfur ions are excessive, the reaction temperature is reasonably controlled, a metal zinc divalent ion (Zn < 2 + >) precursor solution, a Mn < 2 + > precursor solution and adding modes of the metal zinc divalent ion (Zn < 2 + >) precursor solution and the Mn < 2 + > precursor solution are reasonably selected, and the AgZnInS / Mn: ZnS / ZnS quantum dot with Mn < 2 + > doped in a middle shell layer can be prepared. The preparation method is simple, the prepared quantum dot has double fluorescence emission peaks which are respectively emitted from a quantum dot of a substrate and Mn < 2 + > emission, and the fluorescence quantum yield is high. By adjusting the amount of Mn < 2 + > participating in the reaction, the proportion of the matrix quantum dots and Mn < 2 + > emission can be adjusted. The prepared quantum dot is an ideal material for manufacturing a single-phase environment-friendly white light emitting diode.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor nanocrystals, and particularly relates to a new preparation method for doping group I-III-VI-derived quantum dots with divalent metal manganese ions (Mn 2+ ). Background Art

[0002] Semiconductor quantum dots have been widely used in the fields of biological labeling, light-emitting diodes, solar cells, and photocatalytic materials due to their rich and excellent optoelectronic properties. Doped quantum dots mainly involve doping transition metal ions such as Cu, Mn, Ag, Ni or rare earth metal ions into conventional quantum dots such as II-VI, I-III-VI, and perovskite to improve the optoelectronic properties of the base quantum dots or endow the base quantum dots with new optical, electrical, magnetic and other properties. The luminescence mechanism of doped alloy quantum dots is relatively special and mainly depends on the electronic structures of the base quantum dots and the doped ions. The emission peak bandwidth of doped alloy quantum dots is usually larger than that of undoped alloy quantum dots; and a wider quantum dot emission peak bandwidth is beneficial to the research and development of high-performance white light-emitting diodes. Moreover, by adjusting the doping position and doping level (or doping concentration) of the doped ions in the quantum dots, various optical properties of the quantum dots themselves can be further adjusted, especially manifested in the improvement of the emission peak and quantum yield.

[0003] Group I-III-VI and its derived quantum dots, such as AgInS2, CuInS2, AgInGaS, AgInZnS, etc., have received increasing attention because they do not contain heavy metal elements harmful to the natural environment and human body such as Pb and Cd, and have excellent optoelectronic properties. Especially its luminescence properties of large Stokes shift and wide full width at half maximum give it obvious advantages in the field of white light-emitting diodes.

[0004] Mn 2+ Due to 4 T1- 6 A1 transition generates red light emission. By adjusting the ratio of cations in group I-III-VI or its derived quantum dots and synergistically doping with Mn 2+ doping, a dual-emission Mn 2+ doped group I-III-VI or its derived quantum dots containing the emission of the base quantum dots and Mn 2+ emission can be obtained. This dual-reflection environmentally friendly Mn 2+ doped group I-III-VI or its derived quantum dots have more obvious application advantages in the field of white light-emitting diodes and have great application prospects in single-phase environmentally friendly white light-emitting diodes. Description of the Invention

[0005] The object of the present invention is to provide a new environmentally friendly Mn 2+Preparation method of doped I-III-VI group-derived quantum dots. This preparation method has simple process and low energy consumption. The prepared quantum dots have the following characteristics: dual emission peaks, adjustable emission peak positions, adjustable intensity ratios of dual emission peaks, and relatively high quantum yields, etc.

[0006] The present invention adopts the following technical solutions.

[0007] A new Mn 2+ Preparation method of doped I-III-VI group-derived quantum dots, which is characterized by including the following steps:

[0008] (1) Prepare AgZnInS / ZnS quantum dots: Prepare AgZnInS quantum dots, introduce Zn 2+ Precursor solution A is used to perform surface modification on the AgZnInS quantum dots, so as to prepare AgZnInS / ZnS quantum dots;

[0009] (2) Surface adsorption doping: On the basis of the above step (1), cool down and dropwise add Mn with a concentration of x 2+ Precursor solution to perform adsorption doping on the surface of the AgZnInS / ZnS quantum dots;

[0010] (3) Prepare AgZnInS / ZnS:Mn / ZnS quantum dots: On the basis of the above step (2), then heat up, introduce Zn 2+ Precursor solution B is used to perform surface modification on the AgZnInS / ZnS quantum dots that have undergone surface adsorption doping, so as to prepare AgZnInS / ZnS:Mn / ZnS quantum dots.

[0011] Specifically, the Zn 2+ Precursor solution A in the above step (1) is characterized in that its preparation method is: Dissolve 1 mmol of anhydrous zinc acetate (Zn(Ac)2) in 2.5 mL of oleylamine (OAm) and 6 mL of 1-octadecene (1-ODE).

[0012] Specifically, the Mn 2+ Precursor solution in the above step (2) is characterized in that its preparation method is: Dissolve manganese acetate anhydrous (Mn(Ac)2) in 2 mL of oleylamine (OAm).

[0013] Specifically, the Zn 2+ Precursor solution B in the above step (3) is characterized in that its preparation method is: Dissolve 4 mmol of anhydrous zinc acetate (Zn(Ac)2) in 1 mL of 1-dodecanethiol (DDT), 1.5 mL of oleic acid (OA) and 4 mL of 1-octadecene (1-ODE).

[0014] The specific process of preparing the AgZnInS quantum dots in the above step (1) is as follows:

[0015] AgNO3, In(Ac)3, Zn(Ac)2, sulfur powder (S), dodecanethiol (DDT), and oleylamine (OAm) were successively loaded into a three-necked round-bottom flask. Then, while stirring magnetically, the mixture in the flask was heated to 100 °C. The flask was evacuated and then filled with nitrogen, each for 15 min. After thoroughly removing water and oxygen in the reaction apparatus, the mixture in the flask was heated to 180 °C and kept at this temperature for 20 min to obtain a stock solution of AgZnInS quantum dots containing an excessive amount of sulfide ions.

[0016] The ratio y:1:1 of AgNO3, In(Ac)3, and Zn(Ac)2 added to the reaction was adjusted. When this ratio was less than 0.5:1:1, the fluorescence emission wavelength of the obtained AgZnInS quantum dots under the excitation of 365-nm excitation light was less than 530 nm.

[0017] In the preparation of AgZnInS / ZnS quantum dots in step (1) above, the stock solution of AgZnInS quantum dots in the flask was heated to 240 °C, and 8.5 mL of Zn 2+ precursor solution A was rapidly injected, and the reaction was carried out for 90 min to obtain a stock solution of AgZnInS / ZnS quantum dots. At this time, the stock solution of AgZnInS / ZnS quantum dots contained an excessive amount of sulfide ions.

[0018] The surface adsorption doping in step (2) above had the following specific process:

[0019] The stock solution of AgZnInS / ZnS quantum dots in the flask was cooled to 150 °C, and 2 mL of Mn 2+ precursor solution with a concentration of x was added dropwise to the flask, and the reaction was carried out for 60 min to adsorb Mn 2+ onto the surface of ZnS. Preferably, 0.001 mmol / mL ≤ x ≤ 0.006 mmol / mL.

[0020] The preparation of AgZnInS / ZnS:Mn / ZnS quantum dots in step (2) above had the following specific process:

[0021] The stock solution of AgZnInS / ZnS quantum dots surface-adsorbed with Mn 2+ was heated from 150 °C to 240 °C, and 6.5 mL of Zn 2+ precursor solution B was rapidly injected, and the reaction was carried out for 40 min. Then, the heating was stopped, and it was naturally cooled to room temperature to obtain a stock solution of AgZnInS / ZnS:Mn / ZnS quantum dots.

[0022] Further, take 2 mL of the AgZnInS / ZnS:Mn / ZnS quantum dot stock solution and put it into a centrifuge tube. Add 2 mL of n-hexane (C6H 14 ) and shake it; then, add 6 mL of absolute ethanol (CH3CH2OH) and shake it again; then, put the centrifuge tube into a centrifuge and centrifuge it at a speed of 7000 rpm for 5 min; extract the precipitate, which is the purified AgZnInS / ZnS:Mn / ZnS quantum dots.

[0023] According to the specific steps of the AgZnInS / ZnS:Mn / ZnS quantum dots prepared as described in claim 1, if the temperature of the AgZnInS / ZnS quantum dot stock solution is maintained at 240 °C, quickly inject Zn 2+ precursor solution B. After reacting fully for 40 min, stop heating and let it cool naturally to room temperature to obtain the AgZnInS / ZnS / ZnS quantum dot stock solution. After purification, AgZnInS / ZnS / ZnS quantum dots are obtained.

[0024] Further, disperse the purified AgZnInS / ZnS:Mn / ZnS quantum dots in n-hexane (C6H 14 ) solution for fluorescence emission spectrum testing, and the test results are as Figure 1 shown.

[0025] Further, disperse the purified AgZnInS / ZnS:Mn / ZnS quantum dots in n-hexane (C6H 14 ) solution for absolute fluorescence quantum yield testing, and the test results are as Figure 2 shown.

[0026] For easy comparison, the fluorescence emission spectrum and the absolute fluorescence quantum yield of the AgZnInS / ZnS / ZnS quantum dots are also placed in Figure 1 and Figure 2 respectively.

[0027] As Figure 1 shown, for the prepared AgZnInS / ZnS:Mn / ZnS quantum dots, there are two fluorescence emission peaks under the excitation of 365 nm excitation light, which are located near 500 nm and 600 nm respectively, and are the emission of the base quantum dots and Mn 2+ emission respectively. With the addition of Mn in the reaction 2+The concentration of the precursor solution increased from 0.001 mmol / mL to 0.006 mmol / mL. The relative fluorescence intensity of the peak near 500 nm gradually decreased, and the relative fluorescence intensity of the peak near 600 nm gradually increased. Moreover, the fluorescence emission peak near 600 nm was red-shifted from 590 nm to 595 nm. The prepared AgZnInS / ZnS / ZnS quantum dots had a fluorescence emission peak at 510 nm under the excitation of 365 nm excitation light.

[0028] As Figure 2 shown, the absolute fluorescence quantum yield of the prepared AgZnInS / ZnS / ZnS quantum dots under the excitation of 365 nm excitation light was 6.5%. With the addition of Mn in the reaction 2+ The concentration of the precursor solution increased from 0.001 mmol / mL to 0.006 mmol / mL. The absolute fluorescence quantum yield of the prepared AgZnInS / ZnS:Mn / ZnS quantum dots under the excitation of 365 nm excitation light was always higher than that of the AgZnInS / ZnS / ZnS quantum dots, and the highest value was 16.6%. Description of the Drawings

[0029] The drawings described herein are mainly used to illustrate that the prepared quantum dots have the following characteristics: dual emission peaks, adjustable emission peak ratios, and high quantum yields, etc., and do not constitute an improper limitation to this invention.

[0030] Figure 1 is the fluorescence emission spectrum of AgZnInS / ZnS / ZnS and four different doping concentration AgZnInS / ZnS:Mn / ZnS quantum dots; Figure 2 is the absolute fluorescence quantum yield of AgZnInS / ZnS / ZnS and four different doping concentration AgZnInS / ZnS:Mn / ZnS quantum dots. Detailed Embodiments

[0031] This invention is a preparation method of a new Mn 2+ -doped I-III-VI group-derived quantum dots.

[0032] Example 1: Preparation of AgZnInS / ZnS:Mn / ZnS quantum dots, and its specific process includes the following steps:

[0033] Preparation of Zn 2+ Precursor solution A: Dissolve 1 mmol of anhydrous zinc acetate (Zn(Ac)2) in 2.5 mL of oleylamine (OAm) and 6 mL of 1-octadecene (1-ODE).

[0034] Preparation of Zn 2+Precursor solution B: 4 mmol of anhydrous zinc acetate (Zn(Ac)2) was dissolved in 1 mL of n-dodecanethiol (DDT), 1.5 mL of oleic acid (OA) and 4 mL of 1-ODE.

[0035] Prepare Mn with a concentration of 0.004 mmol / mL 2+ Precursor solution: Dissolve 0.008 mmol of anhydrous manganese acetate (Mn(Ac)2) in 2 mL of oleylamine (OAm).

[0036] Preparation of AgZnInS quantum dots: 0.04mmol silver nitrate (AgNO3), 0.2mmol indium acetate (In(Ac)3), 0.2mmol anhydrous zinc acetate (Zn(Ac)2), 2mmol sulfur powder (S), 4mL n-dodecanethiol (DDT) and 6mL oleylamine (OAm) were placed in a 50mL three-necked round-bottom flask in sequence; then, the mixture in the flask was heated to 100°C while magnetically stirring; the flask was evacuated and filled with nitrogen in sequence, each for 15 minutes, and after fully removing water and oxygen in the reaction device, the mixture in the flask was heated to 180°C and kept warm for 20 minutes to obtain the AgZnInS quantum dot stock solution.

[0037] Preparation of AgZnInS / ZnS quantum dots: Heat the AgZnInS quantum dot solution in the flask to 240℃ and quickly inject Zn 2+ After the precursor solution A has fully reacted for 90 minutes, heating is stopped.

[0038] Mn 2+ Adsorption on the ZnS surface: The AgZnInS / ZnS quantum dot stock solution in the flask was cooled to 150°C, and Mn with a concentration of 0.004 mmol / mL was added dropwise. 2+ The precursor solution was added to the flask and fully reacted for 60 minutes.

[0039] Preparation of AgZnInS / ZnS:Mn / ZnS quantum dots: Heat the solution in the above flask to 240℃ and quickly inject Zn 2+ After the precursor solution B was fully reacted for 40 minutes, the heating was stopped and the solution was naturally cooled to room temperature to obtain the AgZnInS / ZnS:Mn / ZnS quantum dot stock solution.

[0040] Purification: Take 2 mL of the AgZnInS / ZnS:Mn / ZnS quantum dot stock solution prepared in step (3) above and place it in a centrifuge tube, add 2 mL of n-hexane (C6H 14)Oscillate; then, add 6 mL of absolute ethanol (CH3CH2OH) and oscillate again; then, place the centrifuge tube in a centrifuge and centrifuge at a speed of 7000 rpm / min for 5 min; extract the precipitate, which is the purified AgZnInS / ZnS:Mn / ZnS quantum dots.

[0041] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A new Mn 2+ Preparation method of doped I-III-V1 group-derived quantum dots, characterized in that Including the following steps: (1) Preparation of AgZnInS / ZnS quantum dots: Prepare AgZnInS quantum dots, and introduce Zn while heating up. 2+ Surface modification of the AgZnInS quantum dots is carried out with precursor solution A, thereby obtaining AgZnInS / ZnS quantum dots. (2) Surface adsorption doping: On the basis of the above step (1), cool down and dropwise add a Mn precursor solution with a concentration of x to perform adsorption doping on the surface of AgZnInS / ZnS quantum dots; 2+ ​ (3) Preparation of AgZnInS / ZnS:Mn / ZnS quantum dots: On the basis of the above step (2), raise the temperature again and introduce Zn. 2+ The precursor solution B is used to perform surface modification on the AgZnInS / ZnS quantum dots doped by surface adsorption to prepare AgZnInS / ZnS:Mn / ZnS quantum dots.

2. The preparation of AgZnInS / ZnS quantum dots according to step (1) in claim 1 is as follows: Silver nitrate (AgNO3), indium acetate (In(Ac)3), anhydrous zinc acetate (Zn(Ac)2), sulfur powder (S), dodecanethiol (DDT), and oleylamine (OAm) are successively loaded into a three-necked round-bottom flask, where the ratio of silver nitrate (AgNO3), indium acetate (In(Ac)3), and anhydrous zinc acetate (Zn(Ac)2) is y:1:1 < 0.5:1:1; then, while stirring magnetically, the mixture in the flask is heated to 100 °C; the flask is evacuated and then filled with nitrogen, each for 15 min. After thoroughly removing water and oxygen in the reaction device, the mixture in the flask is heated to 180 °C and kept warm for 20 min to obtain the stock solution of AgZnInS quantum dots; the stock solution of AgZnInS quantum dots is heated to 240 °C and quickly injected with Zn 2+ precursor solution A, and react for 90 min to obtain the stock solution of AgZnInS / ZnS quantum dots.

3. The AgZnInS quantum dot stock solution and the AgZnInS / ZnS quantum dot stock solution obtained according to that described in claim 2 contain an excessive amount of sulfide ions.

4. Cooling and introducing Mn according to step (2) in claim 1 2+ The precursor solution adsorbs and dopes the surface of AgZnInS / ZnS quantum dots, characterized in that The stock solution of AgZnInS / ZnS quantum dots in the flask was cooled from 240 °C to 150 °C, and a Mn 2+ precursor solution with a concentration of x was added dropwise into the flask, and the reaction was allowed to proceed for 60 min.

5. According to step (2) of claim 1, adding a Mn precursor solution with a certain concentration 2+ , characterized in that By adjusting the concentration of Mn 2+ in the precursor solution, AgZnInS / ZnS:Mn / ZnS quantum dots with different Mn 2+ doping concentrations can be obtained.

6. The preparation of the AgZnInS / ZnS:Mn / ZnS quantum dots according to step (3) in claim 1: It is characterized in that, The AgZnInS / ZnS quantum dot stock solution doped with Mn by surface adsorption is heated from 150 °C to 240 °C, and then Zn 2+ precursor solution B is rapidly injected. After reacting for 40 min, the heating is stopped and it is naturally cooled to room temperature to obtain the AgZnInS / ZnS:Mn / ZnS quantum dot stock solution. 2+ ​ 7. Adjusting Mn according to claim 4 2+ The concentration x of the precursor solution is preferably 0.001 mmol / mL≤x≤0.006 mmol / mL.

8. According to the specific steps of preparing the AgZnInS / ZnS:Mn / ZnS quantum dots described in claim 1, if the surface adsorption doping step is not carried out, that is, the temperature of the AgZnInS / ZnS quantum dot stock solution is maintained at 240 °C, and Zn 2+ precursor solution B is rapidly injected, and after reacting for 40 min, heating is stopped and it is naturally cooled to room temperature to obtain the AgZnInS / ZnS / ZnS quantum dot stock solution.

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