WO2019218310A1

WO2019218310A1 - Quantum dots coated by metal ion pair composite and preparation method therefor

Info

Publication number: WO2019218310A1
Application number: PCT/CN2018/087320
Authority: WO
Inventors: 李良; 李志春; 孙桦
Original assignee: Li Liang; Li Zhichun; Sun Hua
Priority date: 2018-05-17
Filing date: 2018-05-17
Publication date: 2019-11-21
Also published as: CN111433321B; CN111433321A

Abstract

The present invention relates to quantum dots coated by a metal ion pair composite and a preparation method therefor. Quantum dots are pretreated by an alkyl compound (X-R) to create sites for metal ion growth on the surface of quantum dots, a corresponding metal salt is then added to grow the metal ion pair composite by means of a two-phase method, and after the reaction is carried out for a period of time, quantum dots coated by the metal ion pair composite are obtained. Compared with the prior art, the prepared quantum dots coated with the metal ion pair composite have excellent light stability and chemical stability.

Description

Quantum dot coated with metal ion to composite and preparation method thereof

Technical field

The invention belongs to the technical field of semiconductor nanomaterials (quantum dots) preparation, in particular to a quantum dot coated with metal ions and a preparation method thereof.

Background technique

Quantum dots have the advantages of wide wavelength range, narrow half-peak width, high fluorescence quantum efficiency, good electrical transmission performance, low cost, simple processing, etc., and have been widely studied and applied in the fields of optoelectronic devices, display illumination, detection and sensing, etc. Wide attention has been the focus of scholars at home and abroad in recent years. Quantum dots are extremely sensitive to water and oxygen and are susceptible to fluorescence quenching due to the surrounding environment. In addition, the high stability of quantum dots is the basis for the study of physical properties and the development of device applications. How to improve the stability of quantum dots is the primary problem of popularization and application.

At this stage, there are several methods to improve the stability of quantum dots: (1) silica coating. Huang et al. (J. Am. Chem. Soc. 2016, 138, 5749-5752) propose a method for forming silica in an "anhydrous" environment by directly adding methyl orthosilicate to a toluene solution of quantum dots. While hydrolyzing to form silica, the residual moisture in the toluene solution is quickly consumed, and the damage of the perovskite quantum dots by the residual moisture is minimized, and the obtained perovskite quantum dot/SiO ₂ composite is light-stable. Sex has been greatly improved. (2) Polymer coating. Zhou et al. (Adv. Mater. 2016, 28, 9163–9168) prepared a composite film of polyvinylidene fluoride (PVDF) and quantum dots by in-situ polymerization, which has good light transmittance and light stability. (3) Inorganic salts/quantum dot composites. Yang et al. (J. Mater. Chem. C. 2016, 4, 11387-11391) prepared a composite of sodium nitrate and quantum dots. After 14 hours of irradiation on a UV lamp (365 nm, 6 W), the fluorescence intensity was initial. 83%; while the initial quantum dot fluorescence intensity decreased to 2.7% of the original value. (4) Surface treatment method. Koscher et al. (J. Am. Chem. Soc. 2017, 139, 6566-6569) post-treatment of CsPbBr ₃ quantum dots using sodium thiocyanate and ammonium thiocyanate, which not only improves quantum efficiency, but also improves light stability. However, the method of coating a quantum dot with a metal ion at a room temperature to improve the stability thereof has not been disclosed.

The present invention prepares quantum dots coated with metal ions by a two-phase method. Pretreatment of quantum dots with dodecyldimethyl sulfide (S-DDA) or dodecyl dimethyl phosphide (P-DDA) to create sites for ion pair growth, followed by corresponding The metal salt carries out the growth of the ion-pair complex and improves the stability of the quantum dot.

Summary of the invention

In order to further improve the stability of the quantum dots, the present invention provides a quantum dot coated with a metal ion and a preparation method thereof.

The invention can be realized by the following technical solutions: a quantum dot coated with a metal ion to a composite, characterized in that the metal ion has excellent light stability and chemical stability to the composite coated quantum dot.

Step 1) Dissolve a solution of dodecyl dimethylammonium bromide-toluene having a concentration of 0.01-0.2 mmol/mL, labeled as A solution, and at the same time, dispose of sodium hexahydrate in a concentration of 0.01-0.2 mmol/mL or Potassium ethyl xanthate-water solution, labeled as B solution; potassium dihydrogen phosphate or ammonium dihydrogen phosphate-water solution at a concentration of 0.01-0.2 mmol/mL, labeled as C solution; mixed solution A and B solution and sonicated 0.5-2 hours (volume ratio 1:1), after high-speed centrifugation, the above liquid is taken to obtain a dodecyldimethyl sulfide (S-DDA)-toluene solution at a concentration of 0.005-0.1 mmol/mL, labeled as D solution; the same method, the A solution and C solution are mixed to obtain a solution of dodecyl dimethyl phosphide (P-DDA) toluene, the concentration of 0.005-0.1mmol / mL, labeled E solution;

Step 2) Take 50-200 μL of the D solution S-DDA or E solution P-DDA obtained in step 1 is added to the quantum dot solution (10-20 mg/mL), and stirred in the range of 25-70 ° C for 0.5-2 hours;

Step 3) adding 0.01-0.4 mol of the metal salt to the step 2), stirring in the range of 25-70 ° C for 1-4 hours;

Step 4) The quantum dot solution in the step 3) is centrifuged at high speed to remove the unreacted metal salt to obtain a quantum dot coated with the metal ion to the composite.

The quantum dots in the quantum dot solution described in step 2 are non-core-shell quantum dots, core-shell quantum dots, and doped quantum dots.

The dodecyldimethylammonium bromide may be replaced by bis-decyldimethylammonium bromide or dihexadecyldimethylammonium bromide.

Preferably, the B solution is a sodium sulfide nonahydrate-water solution.

Preferably, the C solution is an ammonium dihydrogen phosphate-water solution.

The metal salt is MX, wherein M is lanthanum, cadmium, zinc, mercury, lead, tin, gallium, indium, calcium, strontium, barium, magnesium, strontium, silver or copper. X is an acid ion or a non-acid ion, and also includes chlorinated M, brominated M, fluorinated M, nitric acid M, sulfuric acid M, perchloric acid M, phosphoric acid M, acetic acid M, formic acid M, oxalic acid M, propionic acid M or Acetylacetone M.

The different kinds of metal salts may be added in combination.

The thickness of the coating material is controlled by adjusting the amount of S-DDA or P-DDA, the amount of metal salt added, and the reaction time.

Chemical stability test

(1) Take 1 mL of indium sulfide ion to coat the coated CsPbBr ₃ quantum dot solution, add 1 mL of methyl acetate to clean the quantum dots, and then centrifuge to dissolve in toluene;

(2) repeat the above process and perform different cleaning times;

(3) The chemical stability test of the coated CsPbBr ₃ quantum dot solution was carried out by taking indium sulfide ions of different cleaning times.

Sulfide ion pair coated quantum dot light stability test

Take 2.5 mL of the same amount of quantum dot, sulfide ion pair coated quantum dot solution in a cuvette and seal. The light stability test (450 nm, power density 175 mw/cm2) was carried out under a certain current and voltage, and the fluorescence intensity was measured at a certain time interval, and the intensity of the ratio of the area of the fluorescent peak to the area of the initial fluorescent peak was made - Time decay curve.

Compared with the prior art, the present invention has the following advantages:

The preparation process of the invention is simple,

Compared with the uncoated quantum dots, the prepared metal ions can effectively block the erosion of water vapor and oxygen on the quantum dots by the quantum dots coated by the composite, and the light stability thereof is remarkably improved; at the same time, the chemical stability is improved. Sex.

DRAWINGS

1 is a light attenuation diagram of a coated CsPbBr ₃ quantum dot by a nickel sulfide ion;

2 is a light attenuation diagram of CsPbBr ₃ quantum dots coated with lead sulfide ions;

3 is a light attenuation diagram of CsPbBr ₃ quantum dots coated with indium sulfide ions;

Figure 4 is an optical attenuation diagram of CdSe/CdS/ZnS quantum dots coated with indium sulfide ions.

5 is a graph showing fluorescence changes of coated CsPbBr ₃ quantum dots by indium sulfide ions of different cleaning times;

6 is a light attenuation diagram of a CsPbBr ₃ quantum dot coated with a magnesium sulfide ion pair, a calcium sulfide ion pair, a barium sulfide ion pair, and a barium sulfide ion pair;

Figure 7 is a graph showing the light attenuation of CsPbBr ₃ quantum dots coated with zinc sulfide ion pairs, chromium sulfide ion pairs, and tin sulfide ions.

The invention will be described in detail below with reference to the drawings and specific embodiments.

Example 1

Preparation of Coated CsPbBr ₃ Quantum Dots by Nickel Sulfide Ion

(1) Configuring a 1 mL solution of S2 ^- DDA ⁺ (0.05 mmol/mL) according to the method of claim 1;

(2) 100 μL of S ^2- -DDA ⁺ (0.05 mmol / mL) was added to 1 mL of CsPbBr ₃ quantum dot solution (15 mg / mL), and stirred at 25 ° C for 1 hour;

(3) 0.01 mmol of nickel acetate tetrahydrate was added to the quantum dot solution, and stirred at 25 ° C for 2 hours;

(4) The quantum dot solution was centrifuged at high speed (10000 rpm) for 2 minutes to remove the unreacted metal salt to obtain a CsPbBr ₃ quantum dot coated with nickel sulfide ions.

Figure 1 shows the light attenuation of the coated CsPbBr ₃ quantum dots by nickel sulfide ions. The figure shows that compared with the uncoated CsPbBr ₃ quantum dots, nickel sulfide ions on the stability of light ₃ CsPbBr coated quantum dots were significantly improved.

Example 2

Preparation of coated CsPbBr ₃ quantum dots by lead sulfide ion

(2) 100 μL of S ^2- -DDA ⁺ (0.1 mmol/mL) was added to 1 mL of CsPbBr ₃ quantum dot solution (15 mg/mL), and stirred at 50 ° C for 1 hour;

(3) Adding 0.02 mmol of lead bromide to the quantum dot solution and stirring at 50 ° C for 2 hours;

Figure 2 shows the light attenuation of the coated perovskite quantum dots by lead sulfide ions. The figure shows that compared with the uncoated CsPbBr ₃ quantum dots, lead sulfide ions light stability CsPbBr ₃ coated quantum dots were significantly improved.

Example 3

Preparation of coated CsPbBr ₃ quantum dots by indium sulfide ion

(2) 150 μL of S ^2- -DDA ⁺ (0.05 mmol / mL) was added to 1 mL of CsPbBr ₃ quantum dot solution (15 mg / mL), and stirred at 25 ° C for 1 hour;

(3) adding 0.02 mmol of indium acetate to the quantum dot solution, and stirring at 25 ° C for 3 hours;

Figure 3 shows the light attenuation of the coated CsPbBr ₃ quantum dots by indium sulfide ions. The figure shows that compared with the uncoated CsPbBr ₃ quantum dots, indium sulfide ions on the stability of light ₃ CsPbBr coated quantum dots were significantly improved.

Example 4

Preparation of Coated CdSe/CdS/ZnS Quantum Dots by Indium Sulfide Ion

(2) 150 μL of S ^2- -DDA ⁺ (0.1 mmol / mL) was added to 1 mL of CdSe / CdS / ZnS quantum dot solution (15 mg / mL), and stirred at 70 ° C for 1 hour;

(3) 0.02 mmol of indium acetate was added to the quantum dot solution, and stirred at 70 ° C for 2 hours;

(4) The quantum dot solution was centrifuged at high speed (10000 rpm) for 2 minutes to remove the unreacted metal salt to obtain a CdSe/CdS/ZnS quantum dot coated with nickel sulfide ions.

Figure 4 shows the light attenuation of the coated CdSe/CdS/ZnS quantum dots by indium sulfide ions. As can be seen from the figure, the photostability of the coated CdSe/CdS/ZnS quantum dots is significantly improved compared with the uncoated CdSe/CdS/ZnS quantum dots.

It should be emphasized that the metal ions disclosed in the present invention have good stability to the quantum dots coated by the composite, and many changes and modifications can be made to the above embodiments, and other processing methods such as coating are performed on the basis of the present invention. All such modifications and variations are apparent in the scope of the present disclosure as a result of the improved stability, optical performance and other properties.

Claims

A method for coating a quantum dot with a metal ion pair composite, characterized in that the preparation method of the metal ion-composite coated quantum dot is as follows:

Step 1) Dissolve a solution of dodecyl dimethylammonium bromide-toluene having a concentration of 0.01-0.2 mmol/mL, labeled as A solution, and at the same time, dispose of sodium hexahydrate in a concentration of 0.01-0.2 mmol/mL or Potassium ethyl xanthate-water solution, labeled as B solution; potassium dihydrogen phosphate or ammonium dihydrogen phosphate-water solution at a concentration of 0.01-0.2 mmol/mL, labeled as C solution; mixed solution A and B solution and sonicated 0.5-2 hours (volume ratio 1:1), after high-speed centrifugation, the above liquid is taken to obtain a dodecyldimethyl sulfide (S-DDA)-toluene solution at a concentration of 0.005-0.1 mmol/mL, labeled as D solution; the same method, the A solution and C solution are mixed to obtain a solution of dodecyl dimethyl phosphide (P-DDA) toluene, the concentration of 0.005-0.1mmol / mL, labeled E solution;

Step 2) Take 50-200 μL of the D solution S-DDA or E solution P-DDA obtained in step 1 is added to the quantum dot solution (10-20 mg/mL), and stirred in the range of 25-70 ° C for 0.5-2 hours;

Step 3) adding 0.01-0.4 mol of the metal salt to 2), stirring in the range of 25-70 ° C for 1-4 hours;

Step 4) Centrifuging the quantum dot solution in 3) at high speed to remove the unreacted metal salt to obtain a quantum dot coated with the metal ion to the composite.
The method for coating quantum dots with a metal ion pair composite according to claim 1, wherein the quantum dots in the quantum dot solution in step 2 are non-core-shell quantum dots, core-shell quantum dots, and Doped quantum dots.
A method of coating a quantum dot with a metal ion pair composite according to claim 1, wherein said dodecyldimethylammonium bromide is replaceable with bis-decyldimethylammonium bromide Or dihexadecyldimethylammonium bromide.
The method of coating a quantum dot with a metal ion pair composite according to claim 1, wherein the B solution is a sodium sulphate nonaqueous solution.
The method of coating a quantum dot with a metal ion-pair composite according to claim 1, wherein the C solution is an ammonium dihydrogen phosphate-aqueous solution.
The method for coating a quantum dot with a metal ion pair composite according to claim 1, wherein the metal salt is MX, wherein M is lanthanum, cadmium, zinc, mercury, lead, tin, gallium, indium , calcium, barium, strontium, magnesium, strontium, silver or copper. X is an acid ion or a non-acid ion, and also includes chlorinated M, brominated M, fluorinated M, nitric acid M, sulfuric acid M, perchloric acid M, phosphoric acid M, acetic acid M, formic acid M, oxalic acid M, propionic acid M or Acetylacetone M.
A method of coating quantum dots with a metal ion-pair composite according to claim 1, wherein different kinds of metal salts can be mixedly added.
A method of coating a quantum dot with a sulfide according to claim 1, wherein the control of the thickness of the coating material is achieved by adjusting the amount of S-DDA or P-DDA, the amount of the metal salt added, and the reaction time.