A method for in-situ synthesis of perovskite quantum dots using microwave heating

Abstract

This invention provides a method for in-situ synthesis of perovskite quantum dots using microwave heating, comprising the following steps: adsorbing a perovskite precursor solution into the pores of a micro / mesoporous template to obtain a spatially confined perovskite intermediate; then placing the spatially confined perovskite intermediate in a microwave oven, turning on the microwave, adjusting the power to 50-100W, and setting the microwave time to 1-8 minutes, thereby causing the perovskite precursor to react in the micro / mesoporous template to form perovskite quantum dots through microwave heating. This invention provides a novel solid-state synthesis route for perovskite materials by in-situ synthesis in a template agent using microwave heating.

Description

Technical Field

[0001] This invention belongs to the field of perovskite quantum dot synthesis technology, and particularly relates to a method for in-situ synthesis of perovskite quantum dots using microwave heating. Background Technology

[0002] Lead halide perovskites possess excellent luminescent properties, high energy conversion efficiency, good electrical transport characteristics, unique surface chemistry, and tunable morphology and size. These advantages make them promising candidates for applications in solar cells, light-emitting diodes, lasers, and photodetectors.

[0003] Chinese Patent Publication No. CN 112694888 A discloses a microwave-assisted liquid-phase synthesis of a narrowband green phosphor and its synthesis method. The synthesis method specifically includes the following steps:

[0004] 1) Weigh out cesium bromide and manganese bromide according to the stoichiometric ratio of the elements in the general chemical formula Cs3MnBr5, mix them, add them to deionized water, and shake until the solution is clear to obtain a clear solution.

[0005] 2) Place the clear solution in a microwave oven with a power of 600-900W and microwave it for 1-10 minutes. After the reaction is complete, a pale green narrow-band green phosphor is obtained.

[0006] When heating in a microwave oven, the heat energy comes from the magnetron mounted on the top of the oven. The high-frequency electromagnetic waves emitted by the magnetron can immediately penetrate into the interior of the cesium bromide and manganese bromide solution. At this point, the microwaves encounter polar molecules (water molecules), causing violent molecular oscillations and rapidly generating a large amount of heat through intermolecular friction. During microwave heating, the material is heated simultaneously from the inside out, resulting in uniform heating and a rapid temperature rise, thus significantly shortening the heating time. Furthermore, there is no heat conduction process through the surrounding air during heating, resulting in high heating efficiency.

[0007] However, the microwave heating method mentioned above requires a power of at least 600W, which has the technical disadvantage of high energy consumption. The cost of energy consumption in the preparation process is added to the product itself, making it difficult to carry out the next step of industrial scale-up. Therefore, it needs to be improved. Summary of the Invention

[0008] The purpose of this invention is to provide a method for in-situ synthesis of perovskite quantum dots by microwave heating. This method provides a novel route for the solid-state synthesis of perovskite materials by in-situ synthesis of perovskite materials in a template agent through microwave heating.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for in-situ synthesis of perovskite quantum dots using microwave heating includes the following steps:

[0011] A perovskite precursor solution is adsorbed into the pores using a micro / mesoporous template to obtain a spatially confined perovskite intermediate.

[0012] Next, the spatially confined perovskite intermediate is placed in a microwave oven, the microwave is turned on, the power is adjusted to 50-100W, and the microwave time is set to 1-8 minutes. The perovskite precursor is then reacted in the micro / mesoporous template to form perovskite quantum dots through microwave heating.

[0013] By adopting the above scheme, the microwave power of this invention is 50-100W, far lower than the 600-900W in the prior art. As is well known, the higher the microwave power, the greater the energy it carries, meaning more energy is transferred to the object being heated. Therefore, there is a positive correlation between microwave power and heating temperature.

[0014] In another respect, temperature is a macroscopic manifestation of the intensity of molecular motion. As temperature increases, the speed of molecular motion accelerates, and the frequency and intensity of collisions between molecules increase. While existing technologies promote reactions by increasing microwave power, this invention takes a different approach. The technical principle is as follows:

[0015] This invention pre-adsorbs a perovskite precursor solution within the pores of a micro / mesoporous template, thereby creating a spatially confined perovskite intermediate for the perovskite precursor solution within the pores of the micro / mesoporous template.

[0016] Microwave heating heats the material simultaneously from the inside out, resulting in uniform heating and a rapid temperature rise, thus significantly shortening the heating time. Within a short time, the perovskite precursor solution evaporates in a confined space, instantaneously generating a large amount of vapor within the pores of the micro / mesoporous template. This vapor is difficult to dissipate quickly within the template. According to the ideal gas law: P × V = n × R × T, where n is the number of moles of gas and R is the universal gas constant, the instantaneous generation of a large amount of vapor in a confined space leads to an increase in gas pressure within the pores of the micro / mesoporous template, resulting in an instantaneous pressure greater than the external atmospheric pressure. Under continuous microwave heating, the vapor temperature within the pores of the micro / mesoporous template further increases, providing more energy for the perovskite precursor reaction to form perovskite quantum dots.

[0017] Furthermore, a method for in-situ synthesis of perovskite quantum dots using microwave heating includes the following steps:

[0018] S10: Grind and mix the perovskite precursor and the micro / mesoporous template to obtain a mixed powder;

[0019] S20: The mixed powder is completely dissolved in water to form a precursor solution; then the micro / mesoporous template adsorbs the precursor solution into the pores to obtain a spatially confined perovskite intermediate.

[0020] S30: Place the spatially confined perovskite intermediate in a microwave oven, turn on the microwave, adjust the power to 50-100W, and set the microwave time to 1-8 minutes. Microwave heating causes the perovskite precursor to react in the micro / mesoporous template to form perovskite quantum dots.

[0021] Those skilled in the art can also make adaptive adjustments to the above steps. For example, in step S10, only the perovskite precursor is ground. In step S20, the perovskite precursor is first dissolved in water to form a precursor solution, and then the precursor solution is mixed and stirred with a micro / mesoporous template so that the precursor solution is adsorbed by the pores of the micro / mesoporous template. Such adaptive adjustments to the steps should also fall within the scope of protection of this invention.

[0022] Furthermore, the perovskite quantum dots are of FAPbX3 perovskite structure, CsPbX3 perovskite structure, or CsPbX... y X' 3-y The structure is perovskite, where X and X' are different halogens.

[0023] Furthermore, the perovskite precursor includes a Cs source precursor, a Pb source precursor, and an X source precursor;

[0024] The Cs source precursor is one or more of cesium halide and cesium carbonate;

[0025] The Pb source precursor is one or more of lead halide and lead acetate.

[0026] The halogen source precursor is one or more of the following: cesium halide, lead halide, zinc halide, potassium halide, sodium halide, lithium halide, ammonia halide, calcium halide, strontium halide, and barium halide.

[0027] Furthermore, the micro / mesoporous template is a microporous material and / or a mesoporous material;

[0028] The microporous material is at least one of microporous molecular sieve, microporous silica, microporous titanium dioxide, microporous alumina, microporous transition metal oxide, microporous sulfide, microporous silicate, microporous aluminate or microporous transition metal nitride.

[0029] The mesoporous material is at least one of the following: mesoporous molecular sieve, mesoporous silica, mesoporous titanium dioxide, mesoporous alumina, mesoporous carbon, mesoporous transition metal oxide, mesoporous sulfide, mesoporous silicate, mesoporous aluminate, or mesoporous transition metal nitride.

[0030] Furthermore, the grinding time in step S10 is 10-50 minutes.

[0031] Furthermore, step S20 is a dynamic equilibrium process; the dynamic equilibrium process is as follows: the perovskite precursor dissolves in water to form a precursor solution, which occurs simultaneously with the precursor solution being adsorbed into the pores by the micro / mesoporous template.

[0032] By adopting the above technical solution: step S20 is a dynamic equilibrium process, which eventually reaches dynamic equilibrium over time (i.e., the concentration of the dissolved precursor in the water tends to be uniform everywhere). In the above, "everywhere" can be understood as anywhere within the micro / mesoporous template.

[0033] The beneficial effects of this invention are mainly reflected in the following aspects: Under microwave heating, the perovskite precursor solution located within the pores of the micro / mesoporous template is heated. During the heating process, water is first evaporated to form water vapor. The spatial confinement effect provided by the micro / mesoporous template effectively controls the size of the perovskite quantum dots grown within the pores, ultimately obtaining nanoscale crystals (nanocrystalline). Furthermore, a large amount of vapor is instantaneously generated within the pores of the micro / mesoporous template. This large amount of vapor is difficult to dissipate quickly within the template, thus creating an environment with a pressure higher than the external atmospheric pressure within the pores for a short period. Therefore, under continuous microwave heating, the vapor temperature within the pores of the micro / mesoporous template increases, providing more energy for the perovskite precursor reaction to form perovskite quantum dots. By modifying the existing microwave reaction process and reducing microwave power, the cost burden caused by energy consumption can be reduced in the next industrial scale-up stage. Attached Figure Description

[0034] Figure 1 This is a comparison diagram of the PL spectral intensity of Example 1 and Comparative Examples 1-2 of the present invention;

[0035] Figure 2 This is a comparison diagram of the PL spectral intensity of Example 1 and Comparative Examples 3-4 of the present invention;

[0036] Figure 3 This is a comparison diagram of PL spectral intensity in Examples 1-3 of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0038] Example 1:

[0039] This embodiment provides a method for preparing green perovskite materials by in-situ synthesis in a template agent via microwave heating, including the following steps:

[0040] Step 1: Mix and grind 255.4 mg of cesium bromide, 440.4 mg of lead bromide, and 672 mg of template agent MCM-41 molecular sieve for 30 min.

[0041] Step 2: Put the mixed powder into a 10ml bottle, add 1ml of ultrapure water, and stir well.

[0042] Step 3: Place the bottle in the microwave oven, turn on the microwave, adjust the power to 100W, and set the time to 8 minutes. Microwave heating will cause the perovskite precursor to react in the template agent to form CsPbBr3 perovskite quantum dots.

[0043] Experimental Analysis: The powder obtained by microwave heating was tested, and the resulting spectrum is shown in the figure. Figure 1 The PL spectral intensity of this sample was significantly higher than that of the perovskite calcined at high temperature in Comparative Example 1, the PL spectral intensity of the sample without template agent in Comparative Example 2, the PL spectral intensity of the sample with power exceeding 100W in Comparative Example 3, and the PL spectral intensity of the sample with a time exceeding 10min in Comparative Example 4. This increase in PL spectral intensity indicates that microwave heating can provide a simple and rapid in-situ synthesis of perovskite within a template agent.

[0044] Example 2:

[0045] Step 1: Mix and grind 255.4 mg of cesium bromide, 440.4 mg of lead bromide, and 672 mg of template agent MCM-41 molecular sieve for 30 min.

[0046] Step 2: Put the mixed powder into a 10ml bottle, add 1ml of ultrapure water, and stir well.

[0047] Step 3: Place the bottle in the microwave oven, turn on the microwave, adjust the power to 80W, and set the time to 8 minutes. Microwave heating will cause the perovskite precursor to react in the template agent to form CsPbBr3 perovskite quantum dots.

[0048] Experimental Analysis: The powder obtained by microwave heating was tested, and the resulting spectrum is shown in the figure. Figure 3 .

[0049] Example 3:

[0050] This embodiment provides a method for preparing green perovskite materials by in-situ synthesis in a template agent via microwave heating, including the following steps:

[0051] Step 1: Mix and grind 255.4 mg of cesium bromide, 440.4 mg of lead bromide, and 672 mg of template agent MCM-41 molecular sieve for 30 min.

[0052] Step 2: Put the mixed powder into a 10ml bottle, add 1ml of ultrapure water, and stir well.

[0053] Step 3: Place the bottle in the microwave oven, turn on the microwave, adjust the power to 100W, set the time to 5 minutes, and use microwave heating to cause the perovskite precursor to react in the template agent to form CsPbBr3 perovskite quantum dots.

[0054] Experimental Analysis: The powder obtained by microwave heating was tested, and the resulting spectrum is shown in the figure. Figure 3 .

[0055] Comparative Example 1:

[0056] Comparative Example 1 provides a method for preparing green light perovskite material by high-temperature calcination in a tube furnace, including the following steps:

[0057] Step 1: Mix and grind 255.4 mg of cesium bromide, 440.4 mg of lead bromide, and 672 mg of template agent MCM-41 molecular sieve for 30 min.

[0058] Step 2: Place the mixed powder into the ceramic boat, spread it evenly and press it down.

[0059] Step 3: Place the ceramic boat into a tube furnace, set the temperature to 500℃ and the time to 2 hours, and directly calcine at high temperature to form CsPbBr3 perovskite quantum dots.

[0060] Experimental analysis: The spectrum obtained from the high-temperature calcination synthesis of the green perovskite powder is shown in the figure below. Figure 1 The PL spectral intensity of this sample is lower than that of the perovskites synthesized in situ by microwave heating in Examples 1, 2, and 3.

[0061] Comparative Example 2:

[0062] Comparative Example 2 provides a method for preparing green light perovskite materials through in-situ synthesis by microwave heating, including the following steps:

[0063] Step 1: Mix and grind 255.4 mg of cesium bromide and 440.4 mg of lead bromide for 30 minutes.

[0064] Step 2: Put the mixed powder into a 10ml bottle, add 1ml of ultrapure water, and stir well.

[0065] Step 3: Place the bottle in the microwave oven, turn on the microwave, adjust the power to 100W, and set the time to 8 minutes. Microwave heating will cause the perovskite precursor to react and form CsPbBr3 perovskite quantum dots.

[0066] Experimental analysis: The spectrum obtained from the above-mentioned green perovskite powder without the addition of MCM-41 template agent is shown in the figure. Figure 1 The PL spectral intensity of this sample was lower than that of the perovskites synthesized in situ by microwave heating in Examples 1, 2, and 3. Although Comparative Example 2 used the same microwave power and time as Example 1, since Comparative Example 2 did not have the spatial confinement effect provided by the MCM-41 molecular sieve, the vapor generated by microwave heating of the perovskite precursor dissipated rapidly into the air. This resulted in the microwave reaction temperature provided to the perovskite precursor solution being actually lower than that in Example 1 (i.e., the heat energy contained in the vapor could not be utilized), and thus the reaction did not proceed completely.

[0067] Comparative Example 3:

[0068] This comparative example provides a method for preparing green perovskite materials by in-situ synthesis in a template agent via microwave heating, comprising the following steps:

[0069] Step 1: Mix and grind 255.4 mg of cesium bromide, 440.4 mg of lead bromide, and 672 mg of template agent MCM-41 molecular sieve for 30 min.

[0070] Step 2: Put the mixed powder into a 10ml bottle, add 1ml of ultrapure water, and stir well.

[0071] Step 3: Place the bottle in the microwave oven, turn on the microwave, adjust the power to 150W, and set the time to 8 minutes. Microwave heating will cause the perovskite precursor to react in the template agent to form CsPbBr3 perovskite quantum dots.

[0072] Experimental Analysis: The green perovskite powder synthesized using microwave power of 150W was analyzed, and the resulting spectrum is shown in the figure. Figure 2 The PL spectral intensity of this sample is lower than that of the perovskite synthesized in situ by microwave heating in Example 1.

[0073] Comparative Example 4:

[0074] This comparative example provides a method for preparing green perovskite materials by in-situ synthesis in a template agent via microwave heating, comprising the following steps:

[0075] Step 1: Mix and grind 255.4 mg of cesium bromide, 440.4 mg of lead bromide, and 672 mg of template agent MCM-41 molecular sieve for 30 min.

[0076] Step 2: Put the mixed powder into a 10ml bottle, add 1ml of ultrapure water, and stir well.

[0077] Step 3: Place the bottle in the microwave oven, turn on the microwave, adjust the power to 100W, and set the time to 20 minutes. Microwave heating will cause the perovskite precursor to react in the template agent to form CsPbBr3 perovskite quantum dots.

[0078] Experimental analysis: The green perovskite powder synthesized over the above time of 20 min was used, and the obtained spectrum is shown in the figure. Figure 2 The PL spectral intensity of this sample is lower than that of the perovskite synthesized in situ by microwave heating in Example 1.

[0079] The present invention has been illustrated with the above embodiments to explain the detailed preparation method of the present invention. However, the present invention is not limited to the above detailed preparation method, that is, it does not mean that the present invention must rely on the above product and detailed preparation method to be implemented. Those skilled in the art should understand that any improvement to the present invention, or the combination or equivalent substitution of the raw materials of the present invention, falls within the protection scope and disclosure scope of the present invention.

Claims

1. A method for in-situ synthesis of perovskite quantum dots using microwave heating, characterized in that, Includes the following steps: S10: Grind and mix the perovskite precursor and the microporous or mesoporous template to obtain a mixed powder; S20: The mixed powder is added to water to dissolve the perovskite precursor in water to form a precursor solution. The microporous or mesoporous template adsorbs the precursor solution into the pores to obtain a water-containing and spatially confined perovskite intermediate. Step S20 is a dynamic equilibrium process, which occurs simultaneously with the dissolution of the perovskite precursor in water to form the precursor solution and the adsorption of the precursor solution into the pores by the microporous or mesoporous template. S30: Place the hydrated and spatially confined perovskite intermediate in a microwave oven, turn on the microwave, adjust the power to 50-100W, set the microwave time to 1-8min, and use microwave heating to cause the perovskite precursor to react in a micropore or mesoporous template to form perovskite quantum dots. The perovskite quantum dot is a CsPbX3 perovskite structure, or a CsPbX y X' 3-y perovskite structure, and X and X' are different halogens.

2. The method for in-situ synthesis of perovskite quantum dots by microwave heating according to claim 1, characterized in that, The perovskite precursor includes a Cs source precursor, a Pb source precursor, and an X source precursor. The Cs source precursor is one or more of cesium halide and cesium carbonate; The Pb source precursor is one or more of lead halide and lead acetate. The X source precursor is one or more of cesium halide, lead halide, zinc halide, potassium halide, sodium halide, lithium halide, ammonium halide, calcium halide, strontium halide, and barium halide.

3. The method for in-situ synthesis of perovskite quantum dots by microwave heating according to claim 1, characterized in that, The microporous or mesoporous template is a microporous material or a mesoporous material; The microporous material is at least one of microporous molecular sieve, microporous silica, microporous titanium dioxide, microporous alumina, microporous transition metal oxide, microporous sulfide, microporous silicate, microporous aluminate or microporous transition metal nitride. The mesoporous material is at least one of the following: mesoporous molecular sieve, mesoporous silica, mesoporous titanium dioxide, mesoporous alumina, mesoporous carbon, mesoporous transition metal oxide, mesoporous sulfide, mesoporous silicate, mesoporous aluminate, or mesoporous transition metal nitride.

4. The method for in-situ synthesis of perovskite quantum dots by microwave heating according to claim 1, characterized in that, The grinding time in step S10 is 10-50 minutes.

Images