Perovskite quantum dot all-solid-state preparation method
By adding stannous halides and rare earth metal oxides to the perovskite quantum dot precursor, and combining dynamic sintering and mesoporous material encapsulation, the problem of decreased optical performance of perovskite quantum dots after high-energy grinding was solved, and perovskite quantum dots with smaller particle size and higher stability were prepared.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WENZHOU XINXIN TAIJING TECH CO LTD
- Filing Date
- 2024-12-23
- Publication Date
- 2026-06-23
AI Technical Summary
Existing technologies for preparing perovskite quantum dots struggle to maintain high optical performance and stability while reducing particle size, especially under harsh conditions where they are prone to decomposition, leading to a decline in optical performance.
When using high-energy milled perovskite quantum dot precursors, stannous halides and rare earth metal oxides are added. Through dynamic sintering and annealing, the growth mode and crystallinity of perovskite quantum dots are controlled. Mesoporous materials are used for encapsulation to avoid early formation of perovskite quantum dots. The use of shrinkage agents is combined to improve stability.
This approach achieves high optical performance while reducing particle size, enhances the stability of perovskite quantum dots, resists photo-induced defects, and improves fluorescence quantum yield and particle size control.
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Figure CN122255996A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of quantum dot precursor pretreatment technology, and particularly relates to an all-solid-state preparation method for perovskite quantum dots. Background Technology
[0002] All-inorganic lead-containing perovskite quantum dots have been widely studied and applied in optoelectronic devices due to their advantages such as high fluorescence efficiency, narrow emission, and wide color gamut. However, current lead halide perovskite quantum dot materials struggle to maintain good stability under harsh conditions such as humidity, oxygen, ultraviolet light, and thermal atmospheres, which greatly affects their practical application in the display field.
[0003] To reduce the particle size of synthesized perovskite quantum dots to meet the requirements of quantum dot applications, perovskite precursors are often subjected to high-energy grinding to reduce their size, thereby attempting to synthesize perovskite quantum dots with even smaller particle sizes. However, research has found that perovskite nanocrystals can be directly prepared by grinding the perovskite precursors, such as CN114940903A, CN115197700A, KR1020220161569A, and US6017504A.
[0004] To improve the stability of perovskite quantum dots, current techniques utilize high-temperature calcination to heat the milled perovskite precursor into a molten liquid, which is then adsorbed into the pores of a mesoporous material. Upon cooling and crystallization, this encapsulates the perovskite quantum dots with a layer of mesoporous material. However, due to the high-energy milling of the perovskite precursor, pre-synthesized perovskite quantum dots are present within it, and premature formation of these quantum dots is not desirable. For example, CsPbBr3 perovskite quantum dots are unstable at high temperatures and easily decompose into precursors (such as CsBr and PbBr2), potentially even releasing volatile halogen gases (such as Br2). During decomposition, the stoichiometric ratio of the perovskite components becomes unbalanced, preventing the reformation of a high-quality crystal structure upon cooling and consequently reducing the optical properties of the perovskite.
[0005] Therefore, it is necessary to study how to reduce the particle size of perovskite quantum dots while ensuring their high optical performance, which is an urgent technical problem to be solved. Summary of the Invention
[0006] The purpose of this invention is to provide an all-solid-state preparation method for perovskite quantum dots. This technology enables the high-energy grinding of perovskite precursors without pre-forming perovskite quantum dots, thereby ensuring that while reducing the particle size of perovskite quantum dots, they still possess high optical performance and further resist the generation of photoinduced defects.
[0007] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing perovskite quantum dots in an all-solid state, comprising the following steps:
[0008] S1. Preparation of sintering precursor A: Perovskite quantum dot precursor and stannous halide are added to a grinding equipment for grinding.
[0009] S2. Preparation of sintering precursor B: Mesoporous material, rare earth metal oxide, and shrinkage agent are added to sintering precursor A and then blended and ground.
[0010] S3. Synthesis of perovskite quantum dots: Take the sintering precursor B from step S2 and perform dynamic sintering at a temperature not lower than 500℃ to prepare intermediate products.
[0011] S4. Annealing treatment: Gradually reduce the temperature of the intermediate product in step S3 to the range of 400-485℃ and keep it at that temperature for at least 30 minutes to perform annealing treatment. After annealing treatment, reduce the temperature to room temperature to obtain perovskite quantum dots encapsulated by mesoporous materials.
[0012] Furthermore, the grinding conditions for step S1 are: a rotation speed of at least 200 rpm and a grinding time of at least 15 minutes;
[0013] The grinding conditions for step S2 are: a rotation speed of at least 200 rpm and a grinding time of at least 30 minutes;
[0014] The grinding equipment is at least one of ball mill, pot mill, and grinding mill.
[0015] Furthermore, the mesoporous material is selected from at least one of molecular sieves, mesoporous silica, mesoporous titanium dioxide, mesoporous alumina, mesoporous carbon, mesoporous transition metal oxides, mesoporous sulfides, silicates, aluminates, and transition metal nitrides.
[0016] Furthermore, the perovskite quantum dots have an ABX3 structure; wherein the molar ratio of A, B and X is 1:1:3, and A is Cs, B is Pb, and X is at least one of Cl, Br or I.
[0017] Furthermore, the pore-shrinking agent is at least one or a combination of Ca(OH)2, Al(OH)3, and Al2O3. For example, when Ca(OH)2 is selected as the pore-shrinking agent, Ca(OH)2 decomposes into CaO and water vapor (H2O) upon heating. When Al(OH)3 is selected as the pore-shrinking agent, Al(OH)3 decomposes into Al2O3 and water vapor (H2O) upon heating.
[0018] In other words, the pore-shrinking agent formed during the heating and melting stage and the pore-shrinking agent formed during cooling and crystallization are different substances. Furthermore, both of these pore-shrinking agents generate water vapor after thermal decomposition, which is adsorbed by the mesoporous channels. The presence of trace amounts of water helps improve the quantum efficiency of perovskite quantum dots.
[0019] Furthermore, the dynamic sintering in step S3 includes any one of rotary sintering and stirred sintering; the dynamic sintering process is carried out in a furnace body, which is one of a rotary kiln, a rotary tube furnace, or a stirred reactor.
[0020] Furthermore, the stannous halide is at least one of stannous fluoride, stannous bromide, stannous chloride, and stannous iodide.
[0021] Furthermore, the perovskite quantum dot precursor includes a Cs source precursor, a Pb source precursor, and an X source precursor;
[0022] The Cs source precursor is one or more of cesium halide and cesium carbonate;
[0023] The Pb source precursor is one or more of lead halide and lead acetate.
[0024] The halogen source precursor is one or more of cesium halide, lead halide, zinc halide, potassium halide, sodium halide, lithium halide, ammonia halide, calcium halide, strontium halide, and barium halide.
[0025] Furthermore, the rare earth metal oxide includes at least one of zirconium oxide, yttrium oxide, europium oxide, zirconium-yttrium oxide, cerium oxide, neodymium oxide, samarium oxide, gadolinium oxide, terbium oxide, and scandium oxide.
[0026] Furthermore, the perovskite quantum dots are used in perovskite diffusers, light-emitting devices, wavelength conversion films, quantum dot films, quantum dot light-emitting diodes, or quantum dot masterbatches.
[0027] The beneficial effects of this invention are mainly reflected in:
[0028] (1) This invention adds stannous halides (taking stannous fluoride as an example) to the sintering precursor A for high-energy grinding, which can regulate the growth mode of perovskite quantum dots and improve crystallinity. Specifically: Since SnF2 is a reducing agent, during high-speed grinding, the reactivity increases due to mechanical force, and the oxidation reaction becomes more intense, resulting in the formation of tin oxide (SnO) in the air. It is precisely because SnF2 preferentially reacts with oxygen in the air to form SnO that it dominates the reactivity of the system. The formation of SnO further hinders the contact and reaction of the perovskite quantum dot precursors (CsBr and PbBr2) as the grinding part covers their surfaces. It should be emphasized that during high-speed grinding, the reaction rate of SnF2 is faster, and the reaction priority leads to the inhibition of the reaction of CsBr and PbBr2, weakening the motive force for the formation of CsPbBr3. This allows for the high-energy grinding of perovskite precursors without the pre-formation of perovskite quantum dots, ensuring that while reducing the particle size of perovskite quantum dots, they still possess high optical performance and further resist the generation of photo-induced defects.
[0029] (2) The rare earth metal oxides added in this invention can, on the one hand, play a grinding aid role in the grinding stage and have a size control role (acting as a barrier to prevent agglomeration), thereby effectively reducing the size of mesoporous materials and perovskite quantum dots; on the other hand, they can act as surface modifiers to improve the PLQY and stability of quantum dots. In addition, the pore-shrinking agent also has the effect of acting as a grinding aid.
[0030] (3) Compared with the high-temperature solid-state synthesis of perovskite quantum dots in the prior art, the synthesis technology provided by the present invention can obtain perovskite quantum dots with higher PLQY and smaller particle size. Attached Figure Description
[0031] Figure 1 The PL spectrum of the perovskite quantum dots prepared in Example 1;
[0032] Figure 2 Comparative images of the sintering precursor A powder after grinding in step 1 of Comparative Example 1 and Example 1 are shown.
[0033] Figure 3 The images show a comparison of whether the sintering precursor A powder after grinding in step 1 of Comparative Example 1 and Example 1 emits green light when irradiated with a handheld ultraviolet lamp.
[0034] Figure 4 The image shows the XRD pattern of the sintering precursor A powder after grinding in step 1 of Comparative Example 1.
[0035] Figure 5 The image shows the XRD pattern of the sintering precursor A powder after grinding in step 1 of Example 1. Detailed Implementation
[0036] 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.
[0037] Example 1:
[0038] This embodiment provides a method for the all-solid-state preparation of perovskite quantum dots, including the following steps:
[0039] Step 1: CsBr (94.6g), PbBr2 (149.0g), and SnF2 (6.9g) were added to a ball mill and ground for 0.5h to obtain sintering precursor A. The grinding speed was 350rpm.
[0040] Step 2: Add MCM-41 molecular sieve (183.0g), Ca(OH)2 (20.5g), nanoporous Al2O3 (46.5g), and Eu2O3 (9.1g) to sintering precursor A and grind them together in a ball mill for 1 hour at a speed of 350 rpm to prepare sintering precursor B.
[0041] Step 3: Place the sintering precursor B from Step 2 into a rotary tube furnace and heat it to 550°C at a rate of 10°C / min, and maintain the temperature for 30 minutes. Then, cool it down to 480°C within 30 minutes, hold it at that temperature for 60 minutes, and then allow it to cool naturally. Air is circulated throughout the process to prepare perovskite quantum dots encapsulated by mesoporous materials.
[0042] Step 4: After cooling to room temperature, add pure water at a ratio of 1g phosphor (i.e., the product from Step 3) to 50ml pure water for heating and ultrasonic washing. Heat and stir at 50℃ for 2 hours, with ultrasonic stirring for 1 hour during the process. After washing, centrifuge the product and then transfer it to a washing container for a second wash, following the same washing and centrifugation steps as above. After washing, dry the product in an 80°C oven to obtain perovskite quantum dots.
[0043] Experimental Analysis: The wavelength, fluorescence quantum yield (PLQY), and particle size of the sintered powder were tested, as shown in Table 1. For this sample, the wavelength was 518 nm, the PLQY was 93%, and the D90 was 9.8 μm. The perovskite quantum dots obtained above were mixed with PS material to prepare a quantum dot diffusion plate, and its stability under strong blue light irradiation was tested, as shown in Table 1. After continuous irradiation with 350 mW / cm² blue light (450 nm) for 100 hours, the brightness of the perovskite quantum diffusion plate maintained 95% of its initial intensity.
[0044] Comparative Example 1:
[0045] The difference from Example 1 is that SnF2 is not incorporated in step 1.
[0046] Experimental analysis: The prepared dry powder was tested to obtain a wavelength of 516.6 nm, a PLQY of 83%, and a D90 of 11.0 μm. The perovskite quantum diffusion plate, after 100 hours of blue light irradiation, retained 88% of its initial intensity. This indicates that SnF2 can primarily regulate the growth mode of perovskite quantum dots and improve crystallinity, thereby increasing the final PLQY and reducing the particle size.
[0047] Figure 2 The image on the left shows the sintering precursor A powder after grinding in step 1 of Comparative Example 1.
[0048] Figure 2 The image on the right shows the sintering precursor A powder after grinding in step 1 of Example 1.
[0049] Figure 3 The image on the left shows the sintering precursor A powder after grinding in step 1 of Comparative Example 1 inside a ball mill. The sintering precursor A powder adheres to the surface of the small balls in the ball mill jar and the inner wall of the ball mill jar. When irradiated with a handheld ultraviolet lamp, the sintering precursor A powder emits green light, indicating that CsPbBr3 quantum dots are formed in this step.
[0050] Figure 3 On the right is the sintering precursor A powder after grinding in step 1 of Example 1, inside a ball mill. The sintering precursor A powder adheres to the surface of the small balls in the ball mill jar and the inner wall of the ball mill jar. When irradiated with a handheld ultraviolet lamp, the sintering precursor A powder did not emit green light, indicating that CsPbBr3 quantum dots were not formed in this step.
[0051] Figure 4 The image shows the XRD pattern of the sintering precursor A powder after grinding in step 1 of Comparative Example 1.
[0052] Figure 5 The image shows the XRD pattern of the sintering precursor A powder after grinding in step 1 of Example 1.
[0053] Comparative Example 2:
[0054] The difference from Example 1 is that SnF2 and Eu2O3 are not incorporated in step 1.
[0055] Experimental analysis: The prepared dry powder was tested at a wavelength of 516 nm, with a PLQY of 67% and a D90 of 20.8 μm. The perovskite quantum diffusion plate, after 100 hours of blue light irradiation, retained 85% of its initial intensity. This indicates that Eu2O3 primarily functions as a grinding aid and a size control agent (blocking and preventing agglomeration) during the grinding process, effectively reducing the size of perovskite quantum dots. Secondly, it can act as a surface modifier to improve the PLQY and stability of quantum dots.
[0056] Comparative Example 3:
[0057] The difference from Example 1 is that no nanoporous Al2O3 is incorporated in step 1.
[0058] Experimental analysis: The prepared powder product changed from yellow to white after being soaked in water and stopped luminescent, indicating that the perovskite quantum dots had become ineffective. This suggests that the nanoporous Al2O3 primarily functions as a pore-blocking agent, and its abundant mesoporous structure further coats the quantum dots. Additionally, alumina itself can be used as a grinding aid. Without the pore-blocking effect of nanoporous Al2O3, a significant amount of water enters the pores of the mesoporous material, comes into contact with the perovskite quantum dots, and decomposes them.
[0059] Table 1 shows the performance test results of the samples obtained in Example 1 and Comparative Examples 1-3 of this invention. Among them, blue light stability refers to the stability of the quantum dot diffusion plate, which is the perovskite quantum dots used in Example 1 and Comparative Examples 1-3 to prepare perovskite diffusion plates. The method for preparing the diffusion plates is existing technology and will not be described in detail here.
[0060] The test conditions were as follows: after being continuously irradiated with 350mW / cm2 blue light (450nm) for 100 hours, the brightness of the perovskite quantum dot diffuser plate was able to maintain the initial intensity ratio under white backlight.
[0061] The data methods for wavelength, PLQY, and particle size of the sample products are all existing technologies and will not be elaborated here.
[0062] Table 1: Performance test results of samples from different examples (comparative examples)
[0063]
[0064] 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 preparing perovskite quantum dots entirely in a solid state, characterized in that, Includes the following steps: S1. Preparation of sintering precursor A: Perovskite quantum dot precursor and stannous halide are added to a grinding equipment for grinding. S2. Preparation of sintering precursor B: Mesoporous material, rare earth metal oxide, and shrinkage agent are added to sintering precursor A and then blended and ground. S3. Synthesis of perovskite quantum dots: Take the sintering precursor B from step S2 and perform dynamic sintering at a temperature not lower than 500℃ to prepare intermediate products. S4. Annealing treatment: Gradually reduce the temperature of the intermediate product in step S3 to the range of 400-485℃ and keep it at that temperature for at least 30 minutes to perform annealing treatment. After annealing treatment, reduce the temperature to room temperature to obtain perovskite quantum dots encapsulated by mesoporous materials.
2. The all-solid-state preparation method for perovskite quantum dots according to claim 1, characterized in that, The grinding conditions for step S1 are: a rotation speed of at least 200 rpm and a grinding time of at least 15 minutes; The grinding conditions for step S2 are: a rotation speed of at least 200 rpm and a grinding time of at least 30 minutes; The grinding equipment is at least one of ball mill, pot mill, and grinding mill.
3. The all-solid-state preparation method for perovskite quantum dots according to claim 1, characterized in that, The mesoporous material is selected from at least one of molecular sieves, mesoporous silica, mesoporous titanium dioxide, mesoporous alumina, mesoporous carbon, mesoporous transition metal oxides, mesoporous sulfides, silicates, aluminates, and transition metal nitrides.
4. The all-solid-state preparation method for perovskite quantum dots according to claim 1, characterized in that, The perovskite quantum dots have an ABX3 structure; wherein the molar ratio of A, B and X is 1:1:3, and A is Cs, B is Pb, and X is at least one of Cl, Br or I.
5. The all-solid-state preparation method for perovskite quantum dots according to claim 1, characterized in that, The pore-shrinking agent is at least one of Ca(OH)2, Al(OH)3, and Al2O3, or a combination thereof.
6. The all-solid-state preparation method for perovskite quantum dots according to claim 1, characterized in that, The dynamic sintering in step S3 includes any one of rotary sintering and stirred sintering; the dynamic sintering process is carried out in a furnace body, which is one of a rotary kiln, a rotary tube furnace, or a stirred reactor.
7. The all-solid-state preparation method for perovskite quantum dots according to claim 1, characterized in that, The stannous halide is at least one of stannous fluoride, stannous bromide, stannous chloride, and stannous iodide.
8. The all-solid-state preparation method for perovskite quantum dots according to claim 4, characterized in that, The perovskite quantum dot precursors include Cs source precursors, Pb source precursors, and X source precursors; 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 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.
9. The all-solid-state preparation method for perovskite quantum dots according to claim 1, characterized in that, The rare earth metal oxides include at least one of zirconium oxide, yttrium oxide, europium oxide, zirconium-yttrium oxide, cerium oxide, neodymium oxide, samarium oxide, gadolinium oxide, terbium oxide, and scandium oxide.
10. A method for preparing perovskite quantum dots in an all-solid state according to any one of claims 1-9, characterized in that, The perovskite quantum dots are used in perovskite diffusers, light-emitting devices, wavelength conversion films, quantum dot films, quantum dot light-emitting diodes, or quantum dot masterbatches.