Preparation method for synthesizing perovskite quantum dot CsPbX3 in alkali metal halide

Abstract

The invention discloses a preparation method for synthesizing perovskite quantum dots CsPbX3 in alkali metal halide, which specifically comprises the following steps: dissolving halide in deionized water, and stirring in a water bath kettle to form a precursor solution rich in halogen; adding PbX2, stirring, adding CsX into the halogenated alkali metal solution, and stirring to obtain a mixed solution of perovskite quantum dots and alkali metal halide; and spraying the perovskite quantum dot solution on a glass plate, drying, and crystallizing the alkali metal halide and the perovskite quantum dot at the same time to obtain the perovskite quantum dot CsPbX3 in the alkali metal halide. According to the method, only deionized water is adopted as a solvent, high solubility of an organic reagent to PbX2 is abandoned, a full-inorganic-phase perovskite quantum dot solution is formed, and then the full-inorganic-phase perovskite quantum dot solution is dried to obtain the full-inorganic perovskite quantum dot CsPbX3. In addition, the method is simple to operate, does not adopt an organic reagent, is low in cost and can be popularized on a large scale.

Description

Technical Field

[0001] The invention belongs to the technical field of perovskite quantum dot synthesis, and specifically relates to a preparation method for synthesizing perovskite quantum dots CsPbX3 in alkali metal halides. Background Art

[0002] Perovskite quantum dots have been shining in many optoelectronic fields such as solar cells, lighting and display, photodetection, lasers, and scintillators due to their tunable full-visible spectrum luminescence (410-700 nm), high quantum efficiency (up to 95% or more), high light absorption coefficient, and narrow half-peak width. However, the organic reagents involved in the preparation process not only make the experiment more cumbersome, but also have a great impact on the health and environment of researchers. At the same time, due to the intrinsic ionic characteristics, high surface energy, and metastable structure of perovskite quantum dots, they are highly sensitive to the environment and have poor stability. They are easily decomposed and deteriorated in humid and high-temperature environments. In polar solvent environments, the luminescence intensity and quantum efficiency are still significantly weakened, which also limits their application in real life.

[0003] In order to solve this problem, researchers also use some raw materials to coat perovskite quantum dots, such as sodium docusate (DS), laundry detergent (aromatic sulfonic acid, sulfonate group), SiO2, etc. to prevent the aggregation of perovskite and thus improve the stability of perovskite crystals. However, this is not a green method for preparing highly stable quantum dots CsPbX3. Therefore, designing a fast, simple, cheap, and green method to prepare highly stable perovskite quantum dots is an urgent problem to be solved. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing perovskite quantum dots CsPbX3 in alkali metal halides, which solves the problem that a large amount of organic reagents are used in the existing perovskite quantum dot preparation process and the prepared perovskite quantum dots have poor stability.

[0005] Another object of the present invention is to provide the above-mentioned perovskite quantum dots CsPbX3.

[0006] The technical solution adopted by the present invention is a method for preparing perovskite quantum dots CsPbX3 by synthesizing them in alkali metal halides, which is specifically implemented according to the following steps: Step 1, dissolving a halide in deionized water, placing the water in a water bath and stirring the water to form a halogen-rich precursor solution; Step 2, adding PbX2 to the precursor solution in step 1, stirring, so that PbX2 is dissolved in the alkali metal halide solution; Step 3, adding CsX in an amount equimolar to PbX2 to the alkali metal halide solution in step 2, stirring, to obtain a mixed solution of perovskite quantum dots and alkali metal halide; Step 4, spraying the perovskite quantum dot solution obtained in step 3 onto a glass plate and drying it, so that the alkali metal halide and the perovskite quantum dots are crystallized simultaneously, and the perovskite quantum dots CsPbX3 are obtained in the alkali metal halide.

[0007] The present invention is also characterized in that: In step 1, the halide is KX or NaX.

[0008] X in KX, NaX, CsX, and PbX2 is any one of Cl, Br, and I.

[0009] When X is Cl, the molar mass ratio of the halide to deionized water is 0.003~0.01:5.56; when X is Br, the molar mass ratio of the halide to water is 0.003~0.008:5.56; when X is I, the molar mass ratio of the halide to water is 0.004~0.008:11.11.

[0010] When X is Cl, the molar mass ratio of CsBr, PbX2 and halide is 1:1:1-8; when X is Br, the molar mass ratio of CsX, PbX2 and halide is 1:1:1-5; when X is I, the molar mass ratio of CsX, PbX2 and halide is 1:1:2-6.

[0011] In step 1, the stirring temperature is 40-60°C.

[0012] In step 4, the drying temperature is 70-150°C and the drying time is 10-60min; Another technical solution adopted by the present invention is to prepare the perovskite quantum dots CsPbX3 by a preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides.

[0013] The beneficial effects of the present invention are as follows: in the method of the present invention, only deionized water is used as a solvent, the high solubility of organic reagents for PbX2 is discarded, a fully inorganic perovskite quantum dot solution is formed, and then the solution is dried to obtain fully inorganic perovskite quantum dots CsPbX3 (X=Cl, Br, I); in addition, the method is simple to operate, does not use organic reagents, is low in cost, can be promoted on a large scale, and has important application value in the development of luminescent materials and devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a HRTEM image of perovskite quantum dots CsPbBr3 prepared by the method of the present invention; Figure 2 It is a PL spectrum of perovskite quantum dots CsPbCl3 prepared by the method of the present invention; Figure 3It is a PL spectrum diagram of perovskite quantum dots CsPbBr3 prepared by the method of the present invention; Figure 4 It is a PL spectrum diagram of perovskite quantum dots CsPbI3 prepared by the method of the present invention; Figure 5 This is a thermal stability test chart of the perovskite quantum dots CsPbBr3 prepared by the method of the present invention at 80°C. DETAILED DESCRIPTION

[0015] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, dissolving the halide in deionized water, placing the water in a water bath at 40-60° C. and stirring to form a halogen-rich precursor solution; The halide is KX or NaX; X is Cl, Br or I; When X is Cl, the molar mass ratio of halide to deionized water is 0.003~0.01:5.56; when X is Br, the molar mass ratio of halide to water is 0.003~0.008:5.56; when X is I, the molar mass ratio of halide to water is 0.004~0.008:11.11; Step 2, adding PbX2 to the precursor solution in step 1, stirring, so that PbX2 is dissolved in the alkali metal halide solution; Step 3, adding CsX in an amount equimolar to PbX2 to the alkali metal halide solution in step 2, stirring, to obtain a mixed solution of perovskite quantum dots and alkali metal halide; X in KX, NaX, CsX, and PbX2 is any one of Cl, Br, and I; When X is Cl, the molar mass ratio of CsBr, PbX2, and halide is 1:1:1-8; When X is Br, the molar mass ratio of CsX, PbX2, and halide is 1:1:1-5; When X is I, the molar mass ratio of CsX, PbX2, and halide is 1:1:2-6; The method of the present invention for synthesizing perovskite quantum dots in alkali metal halides has the following advantages: (1) adding water to the raw materials can make the powder dissolve more evenly; (2) no organic reagents are used, ensuring that the experiment is non-toxic and harmless, greatly reducing the complexity of the experiment; (3) the presence of alkali metal halides not only isolates the quantum dot material from direct contact with the environment and improves stability, but also enables the PL emission of the perovskite quantum dots to be optimized.

[0017] Step 4, spraying the perovskite quantum dot solution obtained in step 3 onto a glass plate and drying it, so that the alkali metal halide and the perovskite quantum dots are crystallized simultaneously, and the perovskite quantum dots CsPbX3 (X=Cl, Br, I) are obtained in the alkali metal halide; The drying temperature is 70-150℃ and the drying time is 10-60min; The use of alkali metal halides can increase the solubility of PbX2 in aqueous solution. The reactants are all ionic compounds, which can achieve pure water phase preparation, and finally form perovskite quantum dots at a relatively low temperature and seal them in alkali metal halides. Alkali metal halides can optimize the PL emission of perovskite quantum dots.

[0018] In the method of the present invention, the raw materials for preparing perovskite quantum dots are dissolved in deionized water, and the water provides a place for liquid phase reaction to ensure the uniformity of the reaction. Subsequently, the perovskite quantum dot solution is transferred into a bottle and dried on a glass plate to obtain all-inorganic perovskite quantum dots CsPbX3 (X=Cl, Br, I).

[0019] Example 1 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.52185 g KCl, add it to 100 mL deionized water, place it in a 40°C water bath and stir to form a high concentration KCl solution; Step 2, adding 0.21811 g of PbCl2 to the KCl solution in step 1, stirring thoroughly for 30 min, the solution becomes clear and transparent, and a lead halide ion complex solution is obtained; Step 3, adding 0.16836 g of CsCl to the lead halide ion complex solution of step 2, and stirring for 30 minutes to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spray the perovskite solution of step 3 onto a glass plate at 130° C., collect the powder after drying, and obtain perovskite quantum dots CsPbCl3.

[0020] Example 2 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.4473 g of KCl, add it to 100 mL of deionized water, place it in a 40°C water bath and stir it to form a high concentration KCl solution; Step 2, adding 0.21811 g of PbCl2 to the KCl solution in step 1 and stirring for 30 min, the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.16836 g of CsCl to the lead halide ion complex solution of step 2 and stirring for 30 minutes to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 130° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbCl3.

[0021] Example 3 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.37275 g KCl, add it to 100 mL deionized water, place it in a 40°C water bath and stir to form a high concentration KCl solution; Step 2, add 0.27811 g of PbCl2 to the KCl solution in step 1 and stir thoroughly for 30 minutes until the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.16836 g of CsCl to the lead halide ion complex solution of step 2 and stirring for 30 minutes to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 130° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbCl3.

[0022] Example 4 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.357 g KBr, add it to 100 mL deionized water, place it in a 40°C water bath and stir to form a high concentration KBr solution; Step 2, add 0.36701 g of PbBr2 to the KBr solution in step 1 and stir thoroughly for 30 min until the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.21281 g of CsBr to the lead halide ion complex solution of step 2 and stirring for 30 min to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 110° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbBr3.

[0023] Example 5 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.357 g KBr, add it to 100 mL deionized water, place it in a 40°C water bath and stir to form a high concentration KBr solution; Step 2, add 0.36701 g of PbBr2 to the KBr solution in step 1 and stir thoroughly for 30 min until the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.21281 g of CsBr to the lead halide ion complex solution of step 2 and stirring for 30 min to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 130° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbBr3.

[0024] Example 6 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.357 g KBr, add it to 100 mL deionized water, place it in a 40°C water bath and stir to form a high concentration KBr solution; Step 2, add 0.36701 g of PbBr2 to the KBr solution in step 1 and stir thoroughly for 30 min until the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.21281 g of CsBr to the lead halide ion complex solution of step 2 and stirring for 30 min to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 150° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbBr3.

[0025] Example 7 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.476 g of KBr, add it to 100 mL of deionized water, place it in a 40°C water bath and stir it to form a high concentration KBr solution; Step 2, add 0.36701 g of PbBr2 to the KBr solution in step 1 and stir thoroughly for 30 min until the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.21281 g of CsBr to the lead halide ion complex solution of step 2 and stirring for 30 min to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 130° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbBr3.

[0026] Example 8 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.25896 g of KI, add it to 200 mL of deionized water, place it in a 60°C water bath and stir it to form a high concentration KI solution; Step 2, add 0.124 g PbI2 to the KI solution of step 1 and stir thoroughly for 30 min until the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.0696 g of CsI to the lead halide ion complex solution of step 2 and stirring for 30 minutes to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 110° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbI3.

[0027] Example 9 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.25896 g of KI, add it to 200 mL of deionized water, place it in a 60°C water bath and stir it to form a high concentration KI solution; Step 2, add 0.124 g PbI2 to the KI solution of step 1 and stir thoroughly for 30 min until the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.0696 g of CsI to the lead halide ion complex solution of step 2 and stirring for 30 minutes to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 130° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbI3.

[0028] Example 10 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.25896 g of KI, add it to 200 mL of deionized water, place it in a 60°C water bath and stir it to form a high concentration KI solution; Step 2, add 0.124 g PbI2 to the KI solution of step 1 and stir thoroughly for 30 min until the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.0696 g of CsI to the lead halide ion complex solution of step 2 and stirring for 30 minutes to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 150° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbI3.

[0029] Embodiment 11 The preparation method of synthesizing perovskite quantum dots CsPbX3 in alkali metal halides of the present invention is specifically implemented according to the following steps: Step 1, weigh 0.2158 g of KI, add it to 200 mL of deionized water, place it in a 60°C water bath and stir it to form a high concentration KI solution; Step 2, add 0.124 g PbI2 to the KI solution of step 1 and stir thoroughly for 30 min until the solution becomes clear and transparent to obtain a lead halide ion complex solution; Step 3, adding 0.0696 g of CsI to the lead halide ion complex solution of step 2 and stirring for 30 minutes to obtain a mixed solution of perovskite quantum dots and alkali metal halides; Step 4, spraying the perovskite solution of step 3 onto a glass plate at 150° C., collecting the powder after it dries, and obtaining perovskite quantum dots CsPbI3.

[0030] Figure 1 TEM image of the perovskite quantum dots CsPbBr3 prepared in Example 4 of the present invention. It can be seen from the figure that the quantum dots are evenly distributed inside the KBr, thus proving that the KBr encapsulates the perovskite quantum dots; Figure 2-Figure 4 It is a PL spectrum diagram of the perovskite quantum dot CsPbX3 (X=Cl, Br, I, corresponding to Example 1, Example 5, and Example 11) prepared by the present invention. It can be seen from the figure that the emission wavelength of CsPbCl3 is 464 nm, corresponding to the blue light emitted under the irradiation of ultraviolet lamp, with a half-peak width of 25 nm; the emission wavelength of CsPbBr3 is 520 nm, corresponding to the green light emitted under the irradiation of ultraviolet lamp, with a half-peak width of 21 nm; the emission wavelength of CsPbI3 is 659 nm, corresponding to the red light emitted under the irradiation of ultraviolet lamp, with a half-peak width of 48 nm.

[0031] The perovskite quantum dots CsPbX3 (X=Cl, Br, I) prepared by the present invention have good optical properties, so they are applied to solid-state lighting. The perovskite quantum dots CsPbX3 (X=Cl, Br, I) produce bright blue, green and red primary colors respectively under ultraviolet light irradiation. Monochromatic LEDs can be manufactured by spraying CsPbCl3, CsPbBr3 and CsPbI3 solutions onto GaN blue LED chips respectively. The blue emission band displayed by the electroluminescence spectrum originates from CsPbCl3 quantum dots, the green emission band originates from CsPbBr3 quantum dots, and the red emission band originates from CsPbI3 quantum dots. Bright white light emission can be achieved by adjusting the mass ratio of blue, green and red quantum dots.

[0032] The CsPbBr3 prepared in Example 6 was placed in an oven at 80°C and its emission spectrum was measured every hour. Figure 5 As shown, the emission intensity increases with time, indicating that CsPbBr3 has excellent thermal stability.

Claims

1. A method for preparing perovskite quantum dots CsPbX3 in alkali metal halides, characterized in that: Follow the steps below to implement it: Step 1, dissolving a halide in deionized water, placing the water in a water bath and stirring the water to form a halogen-rich precursor solution; Step 2, adding PbX2 to the precursor solution in step 1, stirring, so that PbX2 is dissolved in the alkali metal halide solution; Step 3, adding CsX in an amount equimolar to PbX2 to the alkali metal halide solution in step 2, stirring, to obtain a mixed solution of perovskite quantum dots and alkali metal halide; Step 4, spraying the perovskite quantum dot solution obtained in step 3 onto a glass plate and drying it, so that the alkali metal halide and the perovskite quantum dots are crystallized simultaneously, and the perovskite quantum dots CsPbX3 are obtained in the alkali metal halide.

2. The method for preparing perovskite quantum dots CsPbX3 in alkali metal halides according to claim 1, characterized in that: In the step 1, the halide is KX or NaX.

3. The method for preparing perovskite quantum dots CsPbX3 in alkali metal halides according to claim 2, characterized in that: X in KX, NaX, CsX, and PbX2 is any one of Cl, Br, and I.

4. The method for preparing perovskite quantum dots CsPbX3 in alkali metal halides according to claim 3, when X is Cl, the molar mass ratio of halide to deionized water is 0.003~0.01:5.56; when X is Br, the molar mass ratio of halide to water is 0.003~0.008:5.56; when X is I, the molar mass ratio of halide to water is 0.004~0.008:11.

11.

5. The method for preparing perovskite quantum dots CsPbX3 in alkali metal halides as claimed in claim 3, wherein when X is Cl, the molar mass ratio of CsBr, PbX2 and halide is 1:1:1-8; when X is Br, the molar mass ratio of CsX, PbX2 and halide is 1:1:1-5; when X is I, the molar mass ratio of CsX, PbX2 and halide is 1:1:2-6.

6. The method for preparing perovskite quantum dots CsPbX3 in alkali metal halides according to claim 1, characterized in that: In the step 1, the stirring temperature is 40-60°C.

7. The method for preparing perovskite quantum dots CsPbX3 in alkali metal halides according to claim 1, characterized in that: In step 4, the drying temperature is 70-150° C. and the drying time is 10-60 min.

8. The perovskite quantum dots CsPbX3 prepared by the method for synthesizing perovskite quantum dots CsPbX3 in alkali metal halide according to any one of claims 1 to 7.

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