Modified perovskite quantum dot and preparation method thereof

Abstract

The invention discloses a modified perovskite quantum dot and a preparation method thereof, belongs to the technical field of perovskite, and overcomes the defect that hydrolysis is difficult to promote and the perovskite quantum dot is difficult to be damaged at the same time in the prior art. The preparation method of the modified perovskite quantum dots comprises the following steps: step 1, preparing a perovskite quantum dot dispersion liquid; 2, mixing the perovskite quantum dot dispersion liquid, a silicon source and / or an aluminum source and organic silicon, and reacting to prepare modified perovskite quantum dots with a coating shell; the organic silicon is # imgabs0 # cyclosilazane or hexamethyl disilazane; the organic silicon is a mixture of the organic silicon and the organic silicon; r is H or # imgabs1; # R1-R9 are respectively and independently selected from H, alkyl, halogenated alkyl, alkenyl or phenyl. According to the method, the purposes of enhancing the hydrolysis coating compactness and protecting the perovskite quantum dots are achieved at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of perovskite, and specifically relates to a modified perovskite quantum dot and a preparation method thereof. Background Art

[0002] With the development of science and technology, 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 material display performance, stability and environmental protection. Compared with traditional semiconductor quantum dots, lead halide perovskite quantum dots have gradually become a strong competitor 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 the practical application in the display field. In response to this, researchers have conducted a lot of 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. The coating layer isolates the quantum dots from the external environment, which can greatly improve the weather resistance and service life of the quantum dots.

[0004] Existing post-processing SiO for perovskite quantum dots x / AlO x The coating technology is mostly carried out under mild conditions. The hydrolysis degree of Si source / Al source is limited, and it is impossible to achieve a relatively thorough hydrolysis to form a dense cross-linked network structure for coating, which greatly weakens the protective effect of the shell material.

[0005] Although the method of providing polarity through the alkaline environment of ammonia water to increase the degree of hydrolysis can effectively promote the hydrolysis of Si source / Al source, it is difficult to avoid the destructive effect on perovskite quantum dots, thereby affecting the optical parameters of perovskite quantum dots.

[0006] In the prior art, it is difficult to achieve the effect of both utilizing an alkaline environment to enhance the hydrolysis coating density and avoiding irreversible damage to quantum dots by the alkaline environment during the post-treatment of the hydrolysis coating shell layer. Summary of the invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that it is difficult to simultaneously promote hydrolysis and avoid the destruction of perovskite quantum dots, thereby providing a modified perovskite quantum dot and a preparation method thereof.

[0008] To this end, the present invention provides the following technical solutions.

[0009] In a first aspect, the present invention provides a method for preparing modified perovskite quantum dots, comprising the following steps:

[0010] Step 1, preparing a perovskite quantum dot dispersion;

[0011] Step 2: mixing the perovskite quantum dot dispersion, silicon source and / or aluminum source, and organosilicon to react and obtain modified perovskite quantum dots with a coating shell;

[0012] The organic silicon is Cyclosilazane or hexamethyldisilurade;

[0013] R is H or

[0014] R1 to R9 are each independently selected from H, alkyl, halogenated alkyl, alkenyl or phenyl.

[0015] Furthermore, the organosilicon is wherein one of R1 to R3 is selected from H, a haloalkyl, an alkenyl or a phenyl group, and the others are each independently selected from an alkyl group; one of R4 to R6 is selected from H, a haloalkyl, an alkenyl or a phenyl group, and the others are each independently selected from an alkyl group;

[0016] Or the organosilicon is R1 to R9 are each independently selected from an alkyl group.

[0017] Furthermore, the organosilicon is hexamethyldisilazane, 1,1,3,3-tetramethyldisilazane, 1,3-diethyl-1,1,3,3-tetramethyldisilazane, 1,3-bis(3,3,3-trifluoropropyl)-1,1,3,3-tetramethyldisilazane, 1,3-diphenyltetramethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, 2,2,4,4,6,6-hexamethylcyclotrisilazane, octamethylcyclotetrasilazane or tris(trimethylsilyl)amine.

[0018] Furthermore, in step 2, the volume ratio of the added amount of silicone to the perovskite quantum dot dispersion is 1:(100-2000), preferably 1:200.

[0019] Furthermore, the concentration of the perovskite quantum dots in the perovskite quantum dot dispersion is 5 to 20 mg / ml, preferably 10 to 15 mg / ml.

[0020] Furthermore, step 2 satisfies at least one of the following conditions:

[0021] (1) The reaction environment humidity is 35-70% RH, preferably 45% RH;

[0022] (2) After adding the organosilicon, the reaction time is 2 to 24 hours, preferably 8 hours.

[0023] Furthermore, in step 1, the perovskite quantum dots prepared are FAa 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 , where 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;

[0024] Preferably FAPbBr3, CsPbBr3 or CsPbBr 1.2 I 1.8 Any one or a combination of at least two of the following.

[0025] Furthermore, the step 1 adopts a solution method to prepare a perovskite quantum dot dispersion;

[0026] Optionally, the solution method is a hot injection method or a room temperature method.

[0027] Furthermore, in step 1, a ligand is added during the preparation of the perovskite quantum dot dispersion;

[0028] The ligand includes at least one of an amino group, a phosphate group, a sulfonic acid group, and a carboxylic acid group;

[0029] The ligand further includes at least one group selected from the group consisting of a siloxane group and an aluminoxane group.

[0030] The ligand is 3-aminopropyltriethoxysilane.

[0031] In a second aspect, the present invention provides a modified perovskite quantum dot prepared according to the above method.

[0032] The technical solution of the present invention has the following advantages:

[0033] 1. The preparation method of modified perovskite quantum dots of the present invention comprises the following steps: step 1, preparing a perovskite quantum dot dispersion; step 2, mixing the perovskite quantum dot dispersion with a silicon source and / or an aluminum source and an organosilicon to react to obtain modified perovskite quantum dots having a coating shell; the organosilicon is Cyclosilazane or hexamethyldisilurazine; R is H or R1 to R9 are each independently selected from H, alkyl, halogenated alkyl or phenyl.

[0034] The present invention introduces organosilicon and silicon source and / or aluminum source into the reaction system at the same time, utilizes the property of organosilicon hydrolysis to generate NH3 or -NH2, and reacts with a very small amount of water during the reaction process, on the one hand, it can provide an alkaline environment to improve the compactness of the hydrolysis coating of the silicon source / aluminum source, and on the other hand, it avoids the damage to the perovskite quantum dots by introducing additional water, and the generated NH3 also has a certain repair effect on the perovskite quantum dots. The present invention provides a mild weak alkaline environment, improves the coating compactness without destroying the characteristics of the perovskite quantum dots, and simultaneously achieves the purpose of enhancing the hydrolysis coating compactness and protecting the perovskite quantum dots.

[0035] As the hydrolysis reaction proceeds, the organosilicon continuously generates new NH3, always maintaining a stable alkaline environment, which can play a pH buffering role and avoid sudden pH changes during the reaction process.

[0036] The alcohols generated by the hydrolysis of silicon and / or aluminum sources increase the polarity of the reaction and also damage the perovskite quantum dots. The hydrolysis products of organic silicon can react with the alcohols generated by the hydrolysis of silicon and / or aluminum sources to generate alkoxysilanes, which can reduce the polarity of excessive alcohols accumulated by the hydrolysis of silicon and aluminum sources and cause damage to the perovskite quantum dots.

[0037] This method is applicable to various reaction environments that require mild alkalinity and has good universality. The method is simple, easy to scale up, and low in cost, which is conducive to industrialization.

[0038] 2. Step 1: Add ligands during the preparation of the perovskite quantum dot dispersion; the ligands include at least one of amino, phosphoric acid, sulfonic acid and carboxylic acid groups; the ligands also include at least one of siloxane and aluminoxane groups. The amino, phosphoric acid, sulfonic acid and carboxylic acid groups at one end of the ligand can coordinate and connect with the surface of the perovskite quantum dots, and the siloxane and aluminoxane groups at the other end can be hydrolyzed to form crosslinks with the outer shell of the perovskite quantum dots, and anchor points are constructed on the surface of the perovskite quantum dots before the silicon source and / or aluminum source are hydrolyzed and coated, which can enhance the firmness of the core-shell connection.

[0039] 3. The modified perovskite quantum dots prepared by the present invention have a perovskite quantum dot core inside and a denser silicon oxide / aluminum oxide shell generated in a weakly alkaline environment on the surface, which can provide a better isolation effect in an aging environment, thereby playing a better protective role and improving the stability of the quantum dots. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 These are the aging and stability test results of the modified organic perovskite quantum dots prepared in Example 1.

[0042] Figure 2 These are the aging and stability test results of the modified organic perovskite quantum dots prepared in Example 2.

[0043] Figure 3 These are the aging and stability test results of the modified organic perovskite quantum dots prepared in Example 3.

[0044] Figure 4 These are the aging and stability test results of the modified organic perovskite quantum dots prepared in Example 4.

[0045] Figure 5 These are the aging and stability test results of the modified organic perovskite quantum dots prepared in Example 5.

[0046] Figure 6 These are the aging and stability test results of the modified organic perovskite quantum dots prepared in Example 6.

[0047] Figure 7 These are the aging and stability test results of the modified organic perovskite quantum dots prepared in Example 7.

[0048] Figure 8 These are the aging and stability test results of the modified organic perovskite quantum dots prepared in Comparative Example 1. DETAILED DESCRIPTION

[0049] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical 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 arts shall fall within the protection scope of the present invention.

[0050] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0051] Example 1

[0052] This embodiment provides a method for preparing modified organic perovskite quantum dots, comprising the following steps:

[0053] (1) Mix 0.432 g of dioctadecyl dimethyl ammonium bromide with 1 ml of 1,3,5-trimethylbenzene and place on a 120°C hot plate until completely dissolved. This mixture is used as a Br precursor.

[0054] (2) 0.054 g of formamidine acetate, 0.102 g of lead acetate trihydrate, 0.617 g of 4-dodecylbenzenesulfonic acid and 10 ml of 1,3,5-trimethylbenzene were added to a three-necked flask and mixed. The mixture was evacuated at room temperature for 10 min, and then N2 was introduced and the temperature was raised to 120°C.

[0055] (3) Use a syringe to extract the Br precursor in (1) and inject it into the reaction system (2). After reacting for 5 seconds, cool it to room temperature in an ice water bath.

[0056] (4) Add 100 μl of 3-aminopropyltriethoxysilane to the crude solution obtained in (3), and stir at room temperature for 30 min.

[0057] (5) Add 30 ml of ethyl acetate to the crude solution obtained in (4), centrifuge at 8000 rpm for 5 min, disperse the precipitate with 10 ml of toluene (Tol), centrifuge again at 5000 rpm for 5 min, and collect the supernatant into a glass bottle.

[0058] (6) Add 500 μl of tetramethoxysilane to the sample in the glass bottle, and then add 50 μl of hexamethyldisilazane thereto, place it in a room temperature, 45% RH humidity environment for reaction for 8 hours, then take it out and centrifuge it at 8000 rpm for 5 minutes.

[0059] (7) The precipitate obtained in (6) was dried in a vacuum oven at 40°C for 4 h, then ground evenly with a mortar and pestle, and placed in a sample bottle for later use.

[0060] Example 2

[0061] This embodiment provides a method for preparing modified organic perovskite quantum dots, which is basically the same as that of Embodiment 1, except that: in (1), 0.1728 g of dioctadecyl dimethyl ammonium bromide, 0.0682 g of potassium iodide and 1 ml of 1,3,5-trimethylbenzene are mixed and placed on a hot plate at 120° C. until completely dissolved, and used as a Br / I precursor.

[0062] Example 3

[0063] This embodiment provides a method for preparing modified organic perovskite quantum dots, which is basically the same as that of Embodiment 1, except that: 500 μl of tetramethoxysilane in (6) is replaced by 500 μl of aluminum sec-butoxide.

[0064] Example 4

[0065] The present embodiment provides a method for preparing modified organic perovskite quantum dots, which is basically the same as that of embodiment 1, except that the perovskite quantum dot synthesis steps (1), (2), and (3) are replaced by: 0.054 g of formamidine acetate, 0.102 g of lead acetate trihydrate, 0.432 g of dioctadecyl dimethyl ammonium bromide, 0.617 g of 4-dodecylbenzenesulfonic acid and 10 ml of dimethyl sulfoxide are mixed evenly, the mixed solution is injected into 30 ml of toluene solution, and then centrifuged at 5000 rpm for 5 min, and dispersed again with 10 ml of toluene.

[0066] Example 5

[0067] This embodiment provides a method for preparing modified organic perovskite quantum dots, which is basically the same as that of Embodiment 1, except that: in (6), 50 μl of hexamethyldisilazane is added instead of 50 μl of 1,1,3,3-tetramethyldisilazane.

[0068] Example 6

[0069] This embodiment provides a method for preparing modified organic perovskite quantum dots, which is basically the same as that of Example 1, except that: (6) 500 μl of tetramethoxysilane is added to the sample in the glass bottle, and then 5 μl of hexamethyldisilazane is added thereto, and the sample is placed in a room temperature, 35% RH humidity environment for reaction for 2 hours, then taken out and centrifuged at 8000 rpm for 5 minutes.

[0070] Example 7

[0071] This embodiment provides a method for preparing modified organic perovskite quantum dots, which is basically the same as that of Example 1, except that: (6) 500 μl of tetramethoxysilane is added to the sample in the glass bottle, and then 50 μl of hexamethyldisilazane is added thereto, and the sample is placed in a room temperature, 60% RH humidity environment for reaction for 24 hours, then taken out and centrifuged at 8000 rpm for 5 minutes.

[0072] Comparative Example 1

[0073] This comparative example provides a method for preparing modified organic perovskite quantum dots, which is basically the same as Example 1, except that: 50 μl of hexamethyldisilazane is not added in (6).

[0074] Test example

[0075] The aging and stability of the modified organic perovskite quantum dots prepared in the examples and comparative examples were tested:

[0076] The prepared modified perovskite quantum dot powder was mixed with film-making glue at a mass ratio of 1:100, and a water oxygen barrier film (10 -2) was packaged and cured by UV light, and cut into 50x50cm films for testing; the film-making glue composition was: 0.3g isobornyl acrylate (IBOA, Aladdin reagent), 0.7g polyurethane acrylate 9014 (Sartomer), and 0.01g 1173 photoinitiator (Foshan Qingbai Chemical).

[0077] Room temperature (CW): place the sample membrane at room temperature and pressure for aging;

[0078] Dry heat aging (HT): The sample film was placed in an oven at 85°C for aging;

[0079] Blue light aging (BL): The sample film is placed under a 1500nits, 450nm LED blue light panel for aging;

[0080] Hygrothermal aging (HH): The sample film is placed in a 65℃ / 95%RH environment for aging;

[0081] Damp heat blue light aging (HHL): The sample film is placed in a 40°C / 85% RH / 8000nits, 450nm LED blue light environment for aging.

[0082] After aging for different times, take the corresponding samples, cool them to room temperature and pressure, and use a fluorescence tester to test the aging and stability of the sample membranes. The results are as follows: Figures 1 to 8 shown.

[0083] The data results of Examples 1-5 show that in the hydrolysis reaction stage, adding an appropriate amount can not only ensure the optical properties of the perovskite quantum dots, but also make them have good stability. Organosilicon can provide a weakly alkaline environment. On the one hand, it can promote a higher degree of hydrolysis and make the coating more compact. On the other hand, the slow-released NH3 makes the overall reaction environment relatively mild and will not damage the quantum dots. In addition, this mild ammonia treatment method is applicable to both green quantum dots and red quantum dots, to synthesis methods such as hot injection method and normal temperature method, to silicon source coating and aluminum source coating, and to other organosilicones that meet the conditions.

[0084] From the comparison of the data results of Example 6 and Comparative Example 1, it can be seen that in the hydrolysis reaction stage, adding a certain amount of organosilicon can improve the stability of the modified perovskite quantum dots; however, in Example 6, the stability of the modified perovskite quantum dots obtained is poorer than that of Example 1 due to the lower concentration of organosilicon, lower humidity and shorter reaction time. This is mainly because the effect of providing a weak alkaline environment in Example 6 is poor, the reaction system is too mild, the hydrolysis reaction is not thorough, and the density of the generated shell is not enough.

[0085] From the comparison of the data results of Example 7 and Comparative Example 1, it can be seen that the addition of a certain amount of silicone can improve the stability of the modified perovskite quantum dots; however, the higher humidity and longer reaction time of Example 7, although it can make the hydrolysis more thorough, also have a certain destructive effect on the perovskite quantum dots, resulting in the stability of the modified perovskite quantum dots being worse than that of Example 1.

[0086] Comparison of the data results of Example 1 and Comparative Example 1 shows that adding silicone during the coating stage can significantly improve its stability. This is because when silicone is not added, the hydrolysis degree of the silicon source is low, the coating is not thorough, which affects the coating density, making it difficult to provide sufficient insulation in an aging environment with humidity, thereby affecting its stability.

[0087] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled 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 methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A method for preparing modified perovskite quantum dots, characterized in that: The following steps are involved: Step 1, preparing a perovskite quantum dot dispersion; Step 2: mixing the perovskite quantum dot dispersion, silicon source and / or aluminum source, and organosilicon to react and obtain modified perovskite quantum dots with a coating shell; The organic silicon is Cyclosilazane or hexamethyldisilurade; R is H or R1 to R9 are each independently selected from H, alkyl, halogenated alkyl, alkenyl or phenyl.

2. The method for preparing modified perovskite quantum dots according to claim 1, characterized in that: The organic silicon is wherein one of R1 to R3 is selected from H, a haloalkyl, an alkenyl or a phenyl group, and the others are each independently selected from an alkyl group; one of R4 to R6 is selected from H, a haloalkyl, an alkenyl or a phenyl group, and the others are each independently selected from an alkyl group; Or the organosilicon is R1 to R9 are each independently selected from an alkyl group.

3. The method for preparing modified perovskite quantum dots according to claim 1, characterized in that: The organosilicon is hexamethyldisilazane, 1,1,3,3-tetramethyldisilazane, 1,3-diethyl-1,1,3,3-tetramethyldisilazane, 1,3-bis(3,3,3-trifluoropropyl)-1,1,3,3-tetramethyldisilazane, 1,3-diphenyltetramethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, 2,2,4,4,6,6-hexamethylcyclotrisilazane, octamethylcyclotetrasilazane or tris(trimethylsilyl)amine.

4. The method for preparing modified perovskite quantum dots according to any one of claims 1 to 3, characterized in that: In the step 2, the volume ratio of the added amount of silicone to the perovskite quantum dot dispersion is 1:(100-2000).

5. The method for preparing modified perovskite quantum dots according to any one of claims 1 to 3, characterized in that: The step 2 satisfies at least one of the following conditions: (1) The reaction environment humidity is 35-70% RH; (2) The reaction time after adding silicone is 2 to 24 hours.

6. The method for preparing modified perovskite quantum dots according to any one of claims 1 to 3, characterized in that: In step 1, the perovskite quantum dots prepared 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 , where 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 FAPbBr3, CsPbBr3 or CsPbBr 1.2 I 1.8 Any one or a combination of at least two of the following.

7. The method for preparing modified perovskite quantum dots according to any one of claims 1 to 3, characterized in that: The step 1 adopts a solution method to prepare a perovskite quantum dot dispersion; Optionally, the solution method is a hot injection method or a room temperature method.

8. The method for preparing modified perovskite quantum dots according to any one of claims 1 to 3, characterized in that: Step 1: adding a ligand during the preparation of a perovskite quantum dot dispersion; The ligand includes at least one of an amino group, a phosphate group, a sulfonic acid group, and a carboxylic acid group; The ligand further includes at least one of a siloxane group and an aluminoxane group.

9. The method for preparing modified perovskite quantum dots according to claim 8, characterized in that: The ligand is 3-aminopropyltriethoxysilane.

10. A modified perovskite quantum dot prepared according to the method for preparing the modified perovskite quantum dot according to any one of claims 1 to 9.

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