Coated perovskite quantum dot and preparation method and application thereof

Abstract

The invention belongs to the technical field of perovskite material preparation, and particularly relates to a coated perovskite quantum dot and a preparation method and application thereof. The method comprises the following steps: (1) synthesizing nanocrystals containing silicon and / or aluminum; and (2) mixing perovskite quantum dots with the nanocrystalline, and reacting to obtain the coated perovskite quantum dots. According to the method, the hydrolysis degree and the coating effect of the perovskite quantum dots are improved, the problems of inactivation, non-uniform dispersion, poor stability and the like of the perovskite quantum dots in the preparation process are avoided, the crystallinity is improved in the crystallization process, and the optical performance of the perovskite quantum dots is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite material preparation, and particularly relates to a coated perovskite quantum dot, a preparation method thereof, and an application thereof. Background Art

[0002] Quantum dot display technology has become one of the most important components of modern optoelectronic products. The popularization and development of optoelectronic products have increasingly higher requirements for many aspects such as the display performance, stability, and environmental friendliness of materials. Compared with traditional semiconductor quantum dots, lead halide perovskite quantum dots have gradually become powerful competitors in the display field in recent years due to their excellent optical properties, low synthesis cost, and environmental friendliness.

[0003] However, the current lead halide perovskite quantum dot materials are difficult to maintain good stability under harsh conditions such as humidity, oxygen environment, ultraviolet light, and thermal atmosphere, which greatly affects their practical applications in the display field. In this regard, researchers have conducted extensive explorations in improving the stability of quantum dots. Among them, the core-shell structure is considered to be one of the effective means to improve the stability of quantum dots. By isolating the quantum dots from the external environment through the coating layer, the weather resistance and service life of the quantum dots can be greatly improved.

[0004] For example, coating quantum dot materials with mesoporous silica to isolate the direct contact between quantum dots and the external environment can significantly improve the environmental tolerance. However, this method of synthesizing perovskite quantum dots by heat treatment has the following defects: the evaporation rate of perovskite precursors varies in a high-temperature environment, resulting in an imbalance in the stoichiometry during the crystallization process, making it difficult to crystallize uniformly, limiting the optical properties of the prepared quantum dots, and having poor batch repeatability. Another example is to use the solution method to coat the surface of quantum dots with tetramethoxysilane by regulating the reaction conditions. Due to the existence of a soft lattice of perovskite, it is difficult to adapt to a strong reaction environment, resulting in a limited degree of hydrolysis reaction, making it difficult to form a denser coating, with a limited shielding effect and unable to completely isolate the environment, and unable to achieve good monodispersity and coating effects. Another example is to physically adsorb perovskite quantum dots with porous materials, first stabilizing the lattice with ligands and then hydrolyzing to coat the outer shell. On the one hand, uneven adsorption is likely to occur during the adsorption process, and a high local concentration is likely to cause quantum dot aggregation. On the other hand, the secondary coating process has no obvious difference from directly coating the quantum dot dispersion liquid, with defects such as low hydrolysis degree and non-dense coating. In addition, during the hydrolysis coating process, the silicon source is affected by the steric hindrance of the ligand, with a large number of independent nucleations, reducing the coating density while affecting the luminescence properties of the quantum dots. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the instability of quantum dots synthesized in the prior art, and thus a coated perovskite quantum dot for improving the stability of quantum dots, a preparation method thereof, and an application thereof are proposed.

[0006] To this end, the present invention provides the following technical solutions.

[0007] The present invention provides a preparation method of perovskite quantum dots coated, comprising the following steps:

[0008] (1) Synthesize nanocrystals containing silicon and / or aluminum;

[0009] (2) Mix the perovskite quantum dots with the nanocrystals, and obtain the perovskite quantum dots coated after reaction.

[0010] In the step (1), the synthesis of the nanocrystals containing silicon and / or aluminum is carried out under acidic conditions;

[0011] Preferably, the pH value of the acidic conditions is 4.5 - 5.5.

[0012] Further, an acidic reagent is used to provide the acidic conditions, and the acidic reagent is at least one of hydrohalic acid, nitric acid, phosphoric acid and sulfuric acid;

[0013] Preferably, the hydrohalic acid is hydrobromic acid.

[0014] Further, the step (1) specifically includes: mixing a silicon source and / or an aluminum source with a solvent, and reacting under acidic conditions to obtain the nanocrystals containing silicon and / or aluminum;

[0015] Preferably, the solvent is at least one of toluene, n - hexane, cyclohexane and mesitylene;

[0016] Preferably, the silicon source has the general formula: [Si(-O - R 1 )(-O - R 2 )(-O - R 3 )(-O - R 4 )] or [R 1 -Si(-O - R 2 )(-O - R 3 )(-O - R 4 )]; wherein, R 1 、R 2 、R 3 、R 4 are each independently selected from a substituted alkyl group or an unsubstituted alkyl group;

[0017] Preferably, in the present invention, the silicon source is any siloxane or inorganic silicon compound that can be hydrolyzed to obtain a silicon oxide compound.

[0018] Preferably, the silicon source is at least one of 3 - aminopropyltrimethoxysilane, 3 - aminopropyltriethoxysilane, 3 - mercaptopropyltriethoxysilane, tetramethoxysilane and tetraethyl orthosilicate;

[0019] Preferably, the aluminum source is at least one of aluminum isopropoxide, aluminum sec-butoxide, aluminum n-butoxide, aluminum tert-butoxide, aluminum triethanolate, trimethylaluminum, tributylaluminum, and basic aluminum acetate.

[0020] Further, the volume ratio of the silicon source to the solvent is 1:(2 - 50);

[0021] Preferably, the volume ratio of the silicon source to the solvent is 1:(8 - 15);

[0022] Preferably, the molar ratio of the aluminum source to the solvent is 1:(10 - 50);

[0023] Preferably, the volume ratio of the acidic reagent to the solvent is 1:(20 - 100);

[0024] Preferably, the volume ratio of the acidic reagent to the solvent is 1:(40 - 60).

[0025] Further, in step (1), when synthesizing the silicon- and / or aluminum-containing nanocrystals, the reaction time is 0.5 - 8 h;

[0026] Preferably, when synthesizing the silicon- and / or aluminum-containing nanocrystals, the reaction time is 3 - 5 h;

[0027] Preferably, in step (2), the reaction time is 0.5 - 8 h;

[0028] Preferably, in step (2), the reaction time is 1 - 3 h.

[0029] Further, in step (2), the molar ratio of the perovskite quantum dots to the nanocrystals is 1:(2 - 30);

[0030] Preferably, the molar ratio of the perovskite quantum dots to the nanocrystals is 1:(5 - 15).

[0031] Step (1) in the synthesis of silicon- and / or aluminum-containing nanocrystals further includes the step of adding absolute ethanol. Adding absolute ethanol can disperse the silicon source and / or aluminum source and prevent the hydrolysis products of the silicon source and / or aluminum source from agglomerating to form large chunks.

[0032] In step (2), the reaction of the perovskite quantum dots and the nanocrystals should be carried out in an environment containing a small amount of water to further hydrolyze the nanocrystals. An aqueous solvent can be added in this process. For example, 95% ethanol can be added. Further, the ratio of the total volume of the perovskite quantum dot dispersion and the nanocrystals to the volume of the aqueous solvent is (1.5 - 10.5):1, preferably 4.4:1.

[0033] The perovskite quantum dots are FA a MA b Cs 1-a-b Pb 1-c-d-e-fZn c Cd d Cu e Mg f Cl m Br n I 3-m-n ;

[0034] Wherein, 0≤a≤1, 0≤b≤1, a + b≤1, 0≤c≤1, 0≤d≤1, 0≤e≤1, 0≤f≤1, c + d + e + f≤1, 0≤m≤3, 0≤n≤3, m + n≤3;

[0035] Preferably, the perovskite quantum dots are FAPbBr 3 、CsPbBr 3 and CsPbBr 1.2 I 1.8 at least one of them.

[0036] The perovskite quantum dots in the present invention can be prepared by methods provided by the prior art, and the preparation method thereof is not limited. For example, the perovskite quantum dots can be prepared by methods such as the hot injection method, the room temperature method, the anti-solvent method, etc.

[0037] The present invention also provides a coated perovskite quantum dot prepared by the above preparation method.

[0038] Furthermore, the present invention also provides an application of the coated perovskite quantum dot prepared by the above preparation method, and the coated perovskite quantum dot is applied to the fields of lighting, display, laser, detection or solar cells.

[0039] The technical solution of the present invention has the following advantages:

[0040] 1. The preparation method of the perovskite quantum dots coated provided by the present invention includes: (1) synthesizing nanocrystals containing silicon and / or aluminum; (2) mixing the perovskite quantum dots with the nanocrystals, and obtaining the perovskite quantum dots coated after reaction. This method not only improves the hydrolysis degree and coating effect of the perovskite quantum dots, but also avoids problems such as inactivation, uneven dispersion, and poor stability of the perovskite quantum dots during the preparation process, improves the crystallinity during the crystallization process, and further improves the optical properties of the perovskite quantum dots. Further, this method first makes the silicon source and / or aluminum source undergo hydrolysis through a pre-hydrolysis method to synthesize nanocrystals containing silicon and / or aluminum, so that silicon and / or aluminum form nanocrystals in the shape of rods, wires or ribbons with a relatively small aspect ratio. Then, they are mixed with the perovskite quantum dots, so that the quantum dots can be evenly dispersed therein. Through the method of secondary hydrolysis for nano-welding, cross-linking is generated between nanocrystals of different shapes, and the quantum dots are surrounded inside the nanocrystals of different shapes to form a coating, obtaining perovskite quantum dots with a core-shell structure; among them, the nanocrystals with a relatively small aspect ratio will not cause uneven distribution of the quantum dots due to adsorption after being mixed with the quantum dots, but can make the quantum dots disperse evenly, improving the effect of coating uniformity.

[0041] Further, the preparation method provided by the present invention has good universality and is applicable to perovskite quantum dots prepared by different methods, such as perovskite quantum dots prepared by the hot injection method, the room temperature method, the anti-solvent method, etc. This method can also regulate the reaction processes of pre-hydrolysis and secondary hydrolysis, has good adjustability, is easy to scale up, and is conducive to industrialization.

[0042] 2. The preparation method of the perovskite quantum dots coated provided by the present invention synthesizes nanocrystals under acidic conditions, and this process does not involve perovskite quantum dots. Using such a relatively intense reaction environment of acidity can improve the hydrolysis degree of the silicon source and / or aluminum source and the crystallinity of the nanocrystals. When mixing the nanocrystals with the perovskite quantum dots, there is no need to carry out the reaction in a strong polar environment. Under mild conditions, the perovskite quantum dots can react with the nanocrystals to obtain the perovskite quantum dots coated, avoiding inactivation and decomposition of the quantum dots, and further improving the optical properties of the perovskite quantum dots.

[0043] Further, the present invention can form nanocrystals in the shape of rods, wires or ribbons under acidic conditions. When the nanocrystals with this structure react with the perovskite quantum dots, the quantum dots can be evenly dispersed. Description of the Drawings

[0044] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0045] Figure 1 It is a transmission electron micrograph of the sample obtained by mixing and stirring the perovskite quantum dot dispersion liquid and silicon-containing nanocrystals for 1 minute in Example 1 of the present invention;

[0046] Figure 2 It is SiO obtained in Example 1 of the present invention x coated FAPbBr 3 transmission electron micrograph of the quantum dot powder sample;

[0047] Figure 3 It is the test results of the stability of Examples 1-10 and Comparative Examples 1-2 of the present invention under different conditions. Specific Embodiments

[0048] The following embodiments are provided to better further understand the present invention. It is not limited to the best embodiment, and does not limit the content and protection scope of the present invention. Any product that is the same or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features falls within the protection scope of the present invention.

[0049] For those not specifying the specific experimental steps or conditions in the embodiments, the operations or conditions of the conventional experimental steps described in the literature in the art can be followed. For the reagents or instruments not specifying the manufacturer, they are all conventional reagent products that can be obtained through commercial purchase.

[0050] Example 1

[0051] This example provides a preparation method for coated perovskite quantum dots, including the following steps:

[0052] (1) Prepare perovskite quantum dots

[0053] Take 0.432 g of dioctadecyldimethylammonium bromide and mix it with 1 ml of 1,3,5-trimethylbenzene, and place it on a hot stage at 120 °C until completely dissolved for use as a Br precursor.

[0054] Take 0.054 g of formamidinium acetate, 0.102 g of lead acetate trihydrate, 0.617 g of 4-dodecylbenzenesulfonic acid, and 10 ml of 1,3,5-trimethylbenzene and add them to a three-necked flask for mixing. After evacuating at room temperature for 10 minutes, introduce N 2, stir continuously at 500 rpm for 30 min, mix it with the Br precursor, and react for 10 min to obtain a crude solution.

[0055] Add 30 ml of ethyl acetate to the crude solution, stir for 1 min, then centrifuge at 4000 rpm for 5 min, pour off the supernatant, disperse the precipitate with 10 ml of toluene, centrifuge at 3000 rpm for 5 min again, take the supernatant and transfer it to a bottle to obtain a perovskite quantum dot dispersion for standby.

[0056] (2) Take 10 ml of toluene solvent, 1 ml of 3-aminopropyltrimethoxysilane and 2 ml of absolute ethanol, mix them and stir for 5 min. Then add 0.2 ml of hydrobromic acid, and the pH of the system is about 5. Continue to stir and react for 4 h, centrifuge at 12000 rpm for 5 min, pour off the supernatant, and redisperse the precipitate with 10 ml of toluene to obtain silicon-containing nanocrystals.

[0057] (3) Take 2 ml of the perovskite quantum dot dispersion (the molar amount of perovskite quantum dots in the dispersion is 0.08 mmol) and 0.2 ml of the silicon-containing nanocrystals obtained in the above step (2) (the molar amount of silicon-containing nanocrystals is 0.6 mmol), mix them, stir for 1 min, then add 0.5 ml of ethanol (95%), continue to stir and react for 2 h, centrifuge at 4000 rpm, and air-dry the precipitate naturally to obtain SiO x -coated FAPbBr 3 quantum dot powder sample.

[0058] Example 2

[0059] This example provides a preparation method for coated perovskite quantum dots, including:

[0060] (1) Preparation of perovskite quantum dots

[0061] Take 0.1728 g of didodecyldimethylammonium bromide, 0.0682 g of potassium iodide and 1 ml of 1,3,5-trimethylbenzene, place them on a hot stage at 120 °C until completely dissolved, and use it as a precursor for standby.

[0062] Take 0.054 g of formamidinium acetate, 0.102 g of lead acetate trihydrate, 0.617 g of 4-dodecylbenzenesulfonic acid and 10 ml of 1,3,5-trimethylbenzene and add them to a three-necked flask for mixing. After evacuating at room temperature for 10 min, introduce N 2 , stir continuously at 500 rpm for 30 min, mix it with the above precursor, and react for 10 min to obtain a crude solution.

[0063] Add 30 ml of ethyl acetate to the crude solution, stir for 1 min, then centrifuge at 4000 rpm for 5 min. Pour off the supernatant, disperse the precipitate in 10 ml of toluene, centrifuge again at 3000 rpm for 5 min, take the supernatant and transfer it to a bottle to obtain a perovskite quantum dot dispersion.

[0064] (2) Mix 10 ml of toluene solvent, 1 ml of 3-aminopropyltrimethoxysilane and 2 ml of absolute ethanol, stir for 5 min, add another 0.2 ml of nitric acid, adjust the pH of the system to about 4.5, continue stirring and reacting for 4 h, centrifuge at 12000 rpm for 5 min, pour off the supernatant, and redisperse the precipitate in 10 ml of toluene to obtain silicon-containing nanocrystals.

[0065] (3) The same as Example 1.

[0066] Example 3

[0067] This example provides a preparation method of coated perovskite quantum dots. The difference from Example 1 lies in the different preparation method of the perovskite quantum dot dispersion. The preparation method of the perovskite quantum dot dispersion includes:

[0068] Mix 0.054 g of formamidinium acetate, 0.102 g of lead acetate trihydrate, 0.432 g of didodecyldimethylammonium bromide, 0.617 g of 4-dodecylbenzenesulfonic acid and 10 ml of dimethyl sulfoxide evenly, inject the mixture into 30 ml of toluene solution, then centrifuge at 3000 rpm for 5 min, and redisperse it in 10 ml of toluene to obtain a perovskite quantum dot dispersion.

[0069] Example 4

[0070] This example provides a preparation method of coated perovskite quantum dots. The difference from Example 1 lies in the different preparation method of the perovskite quantum dot dispersion. The preparation method of the perovskite quantum dot dispersion includes:

[0071] Take 0.432 g of didodecyldimethylammonium bromide and mix it with 1 ml of 1,3,5-trimethylbenzene, place it on a hot stage at 120 °C until completely dissolved, and reserve it as a Br precursor.

[0072] Take 0.054 g of formamidinium acetate, 0.102 g of lead acetate trihydrate, 0.617 g of 4-dodecylbenzenesulfonic acid and 10 ml of 1,3,5-trimethylbenzene and add them to a three-necked flask for mixing. After evacuating at room temperature for 10 min, introduce N 2 , heat up to 120 °C, add the above Br precursor to this reaction system, cool to room temperature with an ice-water bath after reacting for 5 s to obtain a crude solution.

[0073] Add 30 ml of ethyl acetate to the crude solution, stir for 1 min, then centrifuge at 4000 rpm for 5 min. Pour off the supernatant, disperse the precipitate with 10 ml of toluene, centrifuge again at 3000 rpm for 5 min, take the supernatant and transfer it to a bottle to obtain a perovskite quantum dot dispersion for standby.

[0074] Example 5

[0075] This example provides a preparation method of coated perovskite quantum dots. The difference from Example 1 is that 1 ml of 3-aminopropyltrimethoxysilane in step (2) is replaced by 1 ml of aluminum sec-butoxide.

[0076] Example 6

[0077] This example provides a preparation method of coated perovskite quantum dots. The difference from Example 1 is that 1 ml of 3-aminopropyltrimethoxysilane in step (2) is replaced by 1 ml of tetramethoxysilane.

[0078] Example 7

[0079] This example provides a preparation method of coated perovskite quantum dots. The difference from Example 1 lies in step (2). Step (2) of this example includes:

[0080] Take 10 ml of toluene, 0.2 ml of 3-aminopropyltrimethoxysilane and 2 ml of absolute ethanol, mix and stir for 5 min. Then add 0.1 ml of hydrobromic acid, and the pH of the reaction system is about 5.5. Continue to stir and react for 0.5 h, centrifuge at 12000 rpm for 5 min, pour off the supernatant, and redisperse the precipitate with 10 ml of toluene to obtain silicon-containing nanocrystals.

[0081] Example 8

[0082] This example provides a preparation method of coated perovskite quantum dots. The difference from Example 1 lies in step (2). Step (2) of this example includes:

[0083] Take 10 ml of toluene, 5 ml of 3-aminopropyltrimethoxysilane and 2 ml of absolute ethanol, mix and stir for 5 min. Then add 0.5 ml of hydrobromic acid, and the pH of the reaction system is about 4.5. Continue to stir and react for 8 h, centrifuge at 12000 rpm for 5 min, pour off the supernatant, and redisperse the precipitate with 10 ml of toluene to obtain silicon-containing nanocrystals.

[0084] Example 9

[0085] This example provides a preparation method of coated perovskite quantum dots. The difference from Example 1 lies in step (3). Step (3) of this example includes:

[0086] Take 2 ml of perovskite quantum dot dispersion (the molar amount of perovskite quantum dots is about 0.08 mmol) and 0.04 ml of silicon-containing nanocrystals (the molar amount of silicon-containing nanocrystals is 0.12 mmol), mix them, add 0.2 ml of ethanol (95%), continue stirring and reacting for 0.5 h, centrifuge the remaining sample at 4000 rpm, and air-dry the precipitate naturally to obtain SiO x -coated FAPbBr 3 quantum dot powder sample.

[0087] Example 10

[0088] This example provides a preparation method of coated perovskite quantum dots. The difference from Example 1 lies in step (3). Step (3) of this example includes:

[0089] Take 2 ml of perovskite quantum dot dispersion (the molar amount of perovskite quantum dots is about 0.08 mmol) and 0.8 ml of silicon-containing nanocrystals (the molar amount of silicon-containing nanocrystals is 2.4 mmol), mix them, add 1.5 ml of ethanol (95%), continue stirring and reacting for 8 h, centrifuge the remaining sample at 4000 rpm, and air-dry the precipitate naturally to obtain SiO x -coated FAPbBr 3 quantum dot powder sample.

[0090] Comparative Example 1

[0091] This comparative example provides a preparation method of perovskite quantum dots, including the following steps:

[0092] (1) Prepare perovskite quantum dots, the same as in Example 1.

[0093] (2) Take 2 ml of perovskite quantum dot dispersion and 1 ml of 3-aminopropyltrimethoxysilane, add 0.5 ml of ethanol (95%), continue stirring and reacting for 2 h, centrifuge at 4000 rpm, and air-dry the precipitate naturally to obtain SiO x -coated FAPbBr 3 quantum dot powder sample.

[0094] Comparative Example 2

[0095] This comparative example provides a preparation method of perovskite quantum dots, including the following steps:

[0096] (1) Prepare perovskite quantum dots, the same as in Example 1.

[0097] (2) Take 2 ml of perovskite quantum dot dispersion and 1 ml of 3-aminopropyltrimethoxysilane, add 0.5 ml of ethanol (95%) and 0.01 ml of hydrobromic acid, continue stirring and reacting for 2 h, centrifuge at 4000 rpm, and air-dry the precipitate naturally to obtain SiOx Coated FAPbBr 3 Quantum dot powder sample.

[0098] Test Example

[0099] This test example studied the performance of perovskite quantum dots coated in each example and comparative example, specifically as follows:

[0100] (1) Figure 1 It is the transmission electron microscope image of the sample obtained after mixing and stirring the perovskite quantum dot dispersion liquid and silicon-containing nanocrystals in Example 1 for 1 min; Figure 2 is SiO obtained in Example 1 x Coated FAPbBr 3 Transmission electron microscope image of the quantum dot powder sample. From Figure 1 it can be seen that the silicon-containing nanocrystals and FAPbBr 3 Quantum dots are uniformly mixed together, and the quantum dots do not agglomerate; from Figure 2 it can be seen that the silicon-containing nanocrystals and FAPbBr 3 After the quantum dots are stirred and reacted for 2 h, the nanocrystals are crosslinked together, and the FAPbBr 3 Quantum dots are uniformly coated therein, playing a barrier role, indicating that the method of the present invention can prepare SiO x Coated FAPbBr 3 Quantum dots.

[0101] (2) Mix the perovskite quantum dots coated in each example and comparative example with an acrylic resin-based glue in a mass ratio of 1:100, encapsulate them with a water and oxygen barrier film (the barrier performance index of this diaphragm for water and oxygen is 10 -2 g / m 2 ·24 h), cure them by ultraviolet light, cut them into 50×50 cm film sheets, and conduct aging and stability tests after being treated under different conditions. Each condition is as follows:

[0102] Condition 1: Place the film sheet under normal temperature and pressure conditions for testing, and record the experimental results at different times, that is, standing at room temperature (CW).

[0103] Condition 2: Place the film sheet in an 85°C oven for testing, and record the experimental results at different times, that is, dry heat aging (HT).

[0104] Condition 3: Place the film sheet under a 1500 nits, 450 nm LED blue light panel for testing, and record the experimental results at different times, that is, blue light aging (BL).

[0105] Condition 4: Place the film sheet under conditions of 65°C and 95% RH for testing, and record the experimental results at different times, that is, damp heat aging (HH).

[0106] Condition 5: Place the diaphragm in an environment of 40°C, 85% RH, 8000 nits, and 450 nm LED blue light for testing, and record the experimental results at different times, namely high humidity and heat blue light aging (HHL).

[0107] Figure 3 It is the test results of the stability of Examples 1-10 and Comparative Examples 1-2 under different conditions.

[0108] It can be seen from the above experimental results that the results of Examples 1-6 show that the compactness of the coated perovskite quantum dots with a core-shell structure prepared by the method of the present invention is good, which can provide a good isolation effect, and can exhibit good stability in various aging environments, especially the aging resistance performance is more excellent in the humid and hot environment, that is, the stability of the quantum dots is better. This result can further illustrate that the method of the present invention does not damage the optical parameters of the quantum dots. In addition, Examples 1-6 can also illustrate that the present invention can improve the stability of perovskite quantum dots synthesized by different methods such as the thermal injection method and the anti-solvent method, and is applicable to both silicon source coating and aluminum source coating.

[0109] By comparing with Examples 7-10, Example 1 helps to improve the stability and coating compactness of the coated perovskite quantum dots by optimizing the amounts of the silicon source, hydrobromic acid and nanocrystals, as well as the reaction time at each stage.

[0110] Furthermore, comparing Example 1 with Comparative Example 1, the results show that Comparative Example 1 uses a one-step hydrolysis coating. Due to the presence of perovskite quantum dots during the reaction process, the strong reaction environment will damage the quantum dots. Using a mild environment for the reaction results in a lower degree of hydrolysis, and the silicon source cannot effectively coat the perovskite quantum dots, resulting in poor coating compactness, rapid brightness decay during the aging process, and poor stability.

[0111] Comparing Example 1 with Comparative Example 2, the results show that Comparative Example 2 uses a one-step hydrolysis coating and provides a strong reaction environment with hydrobromic acid. Although the coating compactness is improved, according to the experimental results, the stability of the quantum dots obtained in Comparative Example 2 is extremely poor, and the optical parameters are significantly affected. This is because the strong reaction environment provided by hydrobromic acid damages the perovskite quantum dots, and the perovskite lattice is severely damaged and cannot guarantee integrity, resulting in extremely poor stability.

[0112] Obviously, the above examples are only for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A preparation method of perovskite quantum dots coated with characterized in that it comprises the following steps: (1) Synthesize nanocrystals containing silicon and / or aluminum; (2) Mix the perovskite quantum dots with the nanocrystals, and obtain the perovskite quantum dots coated after reaction.

2. The preparation method according to claim 1, characterized in that in the step (1), the synthesis of the nanocrystals containing silicon and / or aluminum is carried out under acidic conditions; Preferably, the pH value of the acidic conditions is 4.5 - 5.

5.

3. The preparation method according to claim 2, characterized in that an acidic reagent is used to provide the acidic conditions, and the acidic reagent is at least one of hydrohalic acid, nitric acid, phosphoric acid and sulfuric acid; Preferably, the hydrohalic acid is hydrobromic acid.

4. The preparation method according to any one of claims 1 - 3, characterized in that the step (1) specifically comprises: mixing a silicon source and / or an aluminum source with a solvent, and reacting under acidic conditions to obtain nanocrystals containing silicon and / or aluminum; Preferably, the solvent is at least one of toluene, n - hexane, cyclohexane and mesitylene; Preferably, the silicon source has the general formula: [Si(-O-R 1 )(-O-R 2 )(-O-R 3 )(-O-R 4 )] or [R 1 -Si(-O-R 2 )(-O-R 3 )(-O-R 4 )]; wherein, R 1 , R 2 , R 3 , R 4 are each independently selected from substituted alkyl groups or unsubstituted alkyl groups; Preferably, the silicon source is at least one of 3 - aminopropyltrimethoxysilane, 3 - aminopropyltriethoxysilane, 3 - mercaptopropyltriethoxysilane, tetramethoxysilane and tetraethyl orthosilicate; Preferably, the aluminum source is at least one of aluminum isopropoxide, aluminum sec - butoxide, aluminum n - butoxide, aluminum tert - butoxide, aluminum triethanolate, trimethylaluminum, tributylaluminum and basic aluminum acetate.

5. The preparation method according to any one of claims 1 - 4, characterized in that the volume ratio of the silicon source to the solvent is 1:(2 - 50); Preferably, the volume ratio of the silicon source to the solvent is 1:(8 - 15); Preferably, the molar ratio of the aluminum source to the solvent is 1:(10 - 50); Preferably, the volume ratio of the acidic reagent to the solvent is 1:(20 - 100); Preferably, the volume ratio of the acidic reagent to the solvent is 1:(40 - 60).

6. The preparation method according to any one of claims 1 - 5, characterized in that in the step (1), when synthesizing the nanocrystals containing silicon and / or aluminum, the reaction time is 0.5 - 8 h; Preferably, when synthesizing the nanocrystals containing silicon and / or aluminum, the reaction time is 3 - 5 h; Preferably, in the step (2), the reaction time is 0.5 - 8 h; Preferably, in the step (2), the reaction time is 1 - 3 h.

7. The preparation method according to any one of claims 1 - 6, characterized in that in the step (2), the molar ratio of the perovskite quantum dots to the nanocrystals is 1:(2 - 30); Preferably, the molar ratio of the perovskite quantum dots to the nanocrystals is 1:(5 - 15).

8. The preparation method according to any one of claims 1 - 7, characterized in that The perovskite quantum dots are FA a MA b Cs 1-a-b Pb 1-c-d-e-f Zn c Cd d Cu e Mg f Cl m Br n I 3-m-n ; wherein, 0 ≤ a ≤ 1, 0 ≤ b ≤ 1, a + b ≤ 1, 0 ≤ c ≤ 1, 0 ≤ d ≤ 1, 0 ≤ e ≤ 1, 0 ≤ f ≤ 1, c + d + e + f ≤ 1, 0 ≤ m ≤ 3, 0 ≤ n ≤ 3, m + n ≤ 3; Preferably, the perovskite quantum dots are FAPbBr 3 , CsPbBr 3 and CsPbBr 1.2 I 1.8 or at least one of them.

9. A perovskite quantum dot coated prepared by the preparation method according to any one of claims 1 - 8.

10. Use of the perovskite quantum dot-coated product prepared by the preparation method according to any one of claims 1-8, characterized in that, the perovskite quantum dot-coated product is applied to the fields of lighting, display, laser, detection or solar cells.

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