CN108531173B

CN108531173B - Silicon dioxide coated cesium lead bromine perovskite nanocrystalline compound and microwave-assisted heating synthesis method thereof

Info

Publication number: CN108531173B
Application number: CN201810565412.8A
Authority: CN
Inventors: 陈碧桑
Original assignee: Minnan Normal University
Current assignee: Minnan Normal University
Priority date: 2018-06-04
Filing date: 2018-06-04
Publication date: 2021-06-11
Anticipated expiration: 2038-06-04
Also published as: CN108531173A

Abstract

The invention discloses a silicon dioxide coated cesium lead bromine perovskite nanocrystalline compound and a microwave-assisted heating synthesis method thereof, wherein a microwave-assisted heating mode is adopted, 1,3,5-tri (bromomethyl) benzene, 3-aminopropyl triethoxysilane, lead stearate and cesium carbonate are used as precursors, octadecene is used as a solvent, and the CsPbBr3@ SiO2 perovskite nanocrystalline compound is synthesized in one step. Compared with CsPbBr3PNCs, the CsPbBr prepared by the invention₃@SiO₂The perovskite nanocrystalline composite has good luminous performance. The method has good reproducibility and is CsPbBr₃SiO of PNCs₂The coating provides a new idea.

Description

Silicon dioxide coated cesium lead bromine perovskite nanocrystalline compound and microwave-assisted heating synthesis method thereof

Technical Field

The invention relates to the technical field of chemical synthesis, in particular to cesium lead bromide (CsPbBr) coated with silicon dioxide₃@SiO₂) Perovskite nanocrystalline complex and microwave-assisted heating synthesis method thereof.

Background

Lead-based Perovskite Nanocrystals (PNCs) are a compound having ABX₃An ionic compound of chemical composition, wherein A⁺Is a monovalent cation (e.g. CH)₃NH₃ ⁺Or Cs⁺)，B²⁺Is Pb²⁺，X^-Is a halide ion (Cl)^-、Br^-、I^-). Since the development in 2014, the synthesis and application of lead-based PNCs have attracted extensive attention. The lead-based PNCs have the advantages of traditional quantum dots, and also have the advantages of mild synthesis conditions (room-temperature synthesis), less light flicker, good defect tolerance, less influence of particle size and the like. The emission wavelength of the PNCs can be changed along with the change of halogen species and substitution ratio besides the regulation of particle size, and generally the emission wavelength is red-shifted along with the increase of X ion radius. Therefore, by adjusting the proportion of Cl, Br and I in the PNCs, the full coverage of the visible light region from blue light to red light of the emission wavelength of the PNCs can be realized. More importantly, the lead-based PNCs have halogen exchange characteristics, namely, halogen in the quantum dots can be exchanged. For example, by CsPbBr₃With CsPbCl₃And CsPbI₃The PNCs can be directly mixed to prepare CsPbCl_xBr_3-xAnd CsPbBr_xI_3-x(x is more than or equal to 0 and less than or equal to 3), the luminous wavelength of the product correspondingly appears blue shift and red shift (shown in figure 1)) And the shift in fluorescence emission wavelength is linearly related to the value of x. Therefore, accurate post-modulation of the luminescence of the lead-based PNCs can be realized through simple halogen exchange (accurate modulation with an error of +/-1 nm can be realized in a position-modulation, 410-670nm emission interval, as shown in FIG. 1, excellent controllability of the fluorescence luminescence wavelength is shown.

At present, two methods of 'internal and external concurrent repair' are mainly used for improving the stability of lead-based PNCs:

(1) the "in-pair" method: the stability of the PNCs or nanocrystals (nanocrystals) is improved by controlling the synthesis method and reaction conditions thereof. Research of Kovalenko subject groups finds that polar solvents such as DMF (dimethyl formamide) and the like introduced in the synthesis process have important influence on the stability of the perovskite nanocrystal, so that a novel method for synthesizing organic-inorganic hybrid nanocrystals by using non-polar solvents is established, and the yield and the stability are improved compared with the conventional DMF solvent-assisted co-precipitation method. The Prieto group utilizes 2-adamantane ammonium salt as an organic amine ligand of a coprecipitation method to obtain MAPBBr 3PNCs with quantum yield of 100%, and in addition, utilizes the main guest action of cucurbit molecules and the ligand to modify the cucurbit molecules on the surfaces of MAPBBr 3PNCs, so that the resistance of the PNCs to polar solvents is improved. The Sargent task group subsequently discovers that oleylamine used in the synthesis process has a corrosion effect on CsPbBr3PNCs, so that the stability of quantum dots is poor, and therefore, the Sargent task group provides a synthesis strategy of an amino-free ligand, and obtains more stable CsPbBr3 PNCs. Therefore, the control of synthesis conditions, methods and ligands is an effective way to improve the stability of lead-based PNCs.

(2) The "external" strategy: the stability of the PNCs or the nanocrystals is improved by coating the PNCs or the nanocrystals with other materials (crystals, polymers and the like). Because the silicon material is low in price and environment-friendly, the stability of the PNCs is improved by coating the PNCs with silicon dioxide, and much attention is paid to the improvement. However, compared with Cd quantum dots, PNCs are ionic crystals, and the structure of the PNCs is easy to collapse due to polar solvents, so that the perovskite nanocrystals are wrapped by SiO2 generated by silane hydrolysis with great difficulty. Although some researchers skillfully utilize trace water in organic solvent toluene to catalyze tetramethoxysilane to hydrolyze to generate SiO2, embedding MAPbBr 3PNCs is realized, and thus the stability of PNCs is remarkably improved. However, because the method uses solvent and trace water in the air, the content of the water is difficult to control and quantify, so the repeatability of the experiment is relatively poor [ similar work uses aminopropyl oxolane as the surface ligand of CsPbX 3PNCs, then the quantum dot solution is exposed in the air and stirred, the coating is realized by the reaction of water molecules in the air and aminopropyl ethoxyalkane, particularly, the CsPb (Br/I) emitting red light has high stability, and the fluorescence quantum efficiency is only reduced by 5% within 3 months. However, the encapsulation using the above method still has some influence on the fluorescence quantum yield of PNCs, because alcohol compounds are also generated during the formation of silica, and the alcohol has some destructive effect on the PNCs. The Rushi Liu subject group of Taiwan traffic university utilizes mesoporous silicon to directly adsorb CsPbBr3PNCs and wraps the CsPbBr3PNCs in silicon matrix, so that the stability of CsPbBr3PNCs is improved, and the mesoporous silicon is applied to a light conversion layer of a white light LED.

The SiO2 coating provides a good idea for improving the stability of the PNCs, but at present, two problems still exist in the coating process of the PNCs: (1) the problem of controllable release of water is that hydrolysis is mainly carried out according to water molecules in a solvent or in the air, and the process is often greatly influenced by the purity of a reagent and the change of weather, has poor reproducibility and consumes time; (2) the fluorescent property of PNCs is greatly influenced by hydrolysis product alcohol, so that the fluorescent property is often deteriorated, and how to realize SiO treatment on PNCs₂The high-efficiency coating has important significance.

Disclosure of Invention

The invention aims to provide a silicon dioxide coated cesium lead bromine perovskite nanocrystalline compound (CsPbBr for short)₃@SiO₂Perovskite nanocrystalline composite) and microwave-assisted heating synthesis method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

CsPbBr₃@SiO₂the microwave-assisted heating synthesis method of the perovskite nanocrystalline composite comprises the following steps: adding Cs into the reaction tube in sequence₂CO₃Lead stearate, 1,3,5-tri (bromomethyl) benzene, octadecene and 3-aminopropyl triethoxysilane, then adding a magnetic stirrer and covering a PEEK card cover, finally placing the reaction tube in a reaction cavity of a microwave synthesizer, and reacting for 6-9min at 140-160 ℃ to obtain CsPbBr₃@SiO₂A perovskite nanocrystalline composite.

The Cs₂CO₃The dosage ratio of the lead stearate to the 1,3,5-tri (bromomethyl) benzene to the octadecene to the 3-aminopropyltriethoxysilane is 30-35mg to 35-40mg to 70-75mg to 5mL to 0.26-0.30 mL.

Preferably, said Cs₂CO₃The ratio of the amount of lead stearate to the amount of 1,3,5-tris (bromomethyl) benzene to the amount of octadecene to 3-aminopropyltriethoxysilane was 32.4mg:38.7mg:71.6mg:5mL:0.28 mL.

Preferably, the reaction temperature is 140 ℃.

Preferably, the reaction time is 6 min.

The rotation speed of the reaction is 1000-1400rpm, and further the rotation speed is 1200 rpm.

By adopting the technical scheme, 1,3,5-tri (bromomethyl) benzene (1,3,5-Tris (bromomethyl) benzene, TBB), 3-Aminopropyltriethoxysilane (3-Aminopropylenethylsiloxane, APTES), lead stearate and cesium carbonate are used as precursors, octadecene is used as a solvent, and the microwave-assisted synthesis is used for the one-step synthesis of CsPbBr₃@SiO₂The perovskite nanocrystalline compound is optimized in synthesis temperature, reaction time and precursor dosage, and CsPbBr is treated by means of XRD, HRTEM, UV-Vis, FL and the like₃@SiO₂The perovskite nanocrystalline composite is characterized and is combined with CsPbBr₃PNCs are compared, and the result shows that CsPbBr₃@SiO₂The perovskite nanocrystalline composite has good luminescence performance and the synthesis method has good reproducibility. The invention is CsPbBr₃SiO of PNCs₂Coating is provided withA new idea.

Drawings

FIG. 1 shows CsPbBr₃PNCs and Cl^-And I^-Fluorescence emission spectrum shift diagram of the mixed product;

FIG. 2 shows the synthesis of CsPbBr by nucleophilic substitution of benzyl bromide with microwave assistance₃@SiO₂A schematic of a perovskite nanocrystalline composite;

FIG. 3 shows CsPbBr in example 1₃@SiO₂An optimal synthesis condition curve of the perovskite nanocrystalline composite;

FIG. 4 shows CsPbBr obtained with different APTES contents in example 2₃@SiO₂A perovskite nanocrystalline composite;

FIG. 5 is a graph showing the result of batch-to-batch synthesis in example 2 (fluorescence under UV-365nm UV lamp);

FIG. 6 shows CsPbBr in example 4₃@SiO₂XRD spectrogram (a) of product and CsPbBr₃@SiO₂A fluorescence spectrum (b);

FIG. 7 shows CsPbBr in example 4₃@SiO₂And its HRTEM images (b);

FIG. 8 shows CsPbBr in example 4₃@SiO₂EDS diagram.

Detailed Description

CsPbBr₃@SiO₂The microwave-assisted heating synthesis method of the perovskite nanocrystalline composite comprises the following steps: adding Cs into the reaction tube in sequence₂CO₃Lead stearate, 1,3,5-tri (bromomethyl) benzene, octadecene and 3-aminopropyl triethoxysilane, adding a magnetic stirrer, and placing the reaction tube in a reaction chamber of a microwave synthesizer for reaction at 140-160 deg.C for 6-9min to obtain CsPbBr₃@SiO₂A perovskite nanocrystalline composite;

wherein, Cs₂CO₃The dosage ratio of the lead stearate, the 1,3,5-tri (bromomethyl) benzene, the octadecene and the 3-aminopropyltriethoxysilane is 30-35mg:35-40mg:70-75mg:5mL:0.26-0.30mL, preferably 32.4mg:38.7mg:71.6mg:5mL:0.28 mL.

The above synthesis scheme is shown in FIG. 2a, and the whole synthesis process is tenSimple and convenient, and can generate the CsPbBr product only by adding all precursors and solvents into a reaction tube and heating for a certain time₃@SiO₂. The specific mechanism is as follows: -NH in TBB and APTES₂Nucleophilic substitution reaction occurs, and released HBr attacks Cs₂CO₃And lead stearate to corresponding CO₂、H₂O, CsBr and PbBr₂Wherein CsBr and PbBr₂Rapid generation of CsPbBr₃And H is₂Formation of SiO by O and siloxane₂Finally, CsPbBr is generated₃@SiO₂。

Some of the reagents and experimental equipment used in the present invention are shown in tables 1 and 2.

TABLE 1 chemical reagent Table related to the experiment

TABLE 2 Main test equipment table

The present invention will be described in further detail with reference to specific examples below:

example 1

Discussion of optimal Synthesis temperature and time

16.3mg of Cs were sequentially added to the reaction tube₂CO₃38.7mg lead stearate, 71.6mg TBB, 5mL ODE and 0.28mL APTES, then adding a small stirrer, covering a PEEK card cover, and finally putting into a reaction chamber of a microwave synthesizer. Discussing the reaction conditions at different temperatures of 80, 100, 120, 140 and 160 ℃ (the reaction time is 6min, and the rotating speed is 1200 rpm); under the optimal temperature, the reaction conditions of different reaction times of 3min, 6min, 9min and 12min are discussed.

Due to CsPbBr₃The generation energy is very low, so the rapid temperature rise is beneficial to the rapid nucleation and growth, thereby obtaining better optical performance. In the experimental process, the precursor can not be completely reacted when the temperature is lower than 140 ℃, bright yellow-green products are generated when the temperature reaches 140 ℃, and bright fluorescence is emitted under a 365nm ultraviolet lamp. No obvious difference exists at 160 ℃, so the temperature is 140 ℃; also, it was found in the experiment that when the time was 3min, there was unreacted precursor at the bottom, and when the time was 6min, the reaction was complete, and further extension of the time did not show performance improvement, so the optimum time was 6 min. The working curve of the optimal reaction conditions is shown in fig. 3.

Example 2

Discussion of precursor proportions

First, 5mL of octadecene solution was added to the reaction tube, and then different Cs contents were added accurately₂CO₃Lead stearate, TBB and APTE in a reaction tube so that the molar ratio of Cs to APTE₂CO₃: lead stearate: TBB: other ratios, such as APTE 1:1:3:1, 2:1:3:1, etc., were used to investigate the effect of different precursor ratios on product performance at the optimal reaction temperature and time as determined in example 1.

By optimizing the proportion of different precursors, the experiment shows that Cs is the same as Cs₂CO₃32.4mg of CsPbBr, 38.7mg of lead stearate, 71.6mg of TBB and 280uL of APTES₃@SiO₂The effect is best, and the dispersibility and the fluorescence property of the fluorescent material are obviously superior to those of other proportions. As shown in FIG. 4, when APTES is 280uL, CsPbBr₃@SiO₂No obvious precipitation, small and uniform particles, and good fluorescence under the ultraviolet lamp box. Further, the reproducibility of the synthesis was examined, and it was found that the fluorescence was substantially uniform when the synthesis was performed 5 times, as shown in FIG. 5, indicating that the reproducibility of the method was good.

Example 3

CsPbBr₃@SiO₂The microwave-assisted heating synthesis method of the perovskite nanocrystalline composite comprises the following steps:

32.4mg of Cs were sequentially added to the reaction tube₂CO₃38.7mg of stearinLead acid, 71.6mg TBB, 5mL octadecene and 280uL APTES, then adding a magnetic stirrer, finally placing the reaction tube in a reaction chamber of a microwave synthesizer, and reacting for 6min at 140 ℃ to obtain CsPbBr₃@SiO₂A perovskite nanocrystalline composite;

CsPbBr₃@SiO₂the structural properties and the fluorescent properties of (A) are shown in FIG. 6, wherein CsPbBr is shown in FIG. 6(a)₃@SiO₂XRD spectrogram; FIG. 6(b) shows CsPbBr₃@SiO₂Fluorescence spectrogram (obtained product CsPbBr)₃@SiO₂Fluorescence under the irradiation of an ultraviolet lamp at U V-365 nm); FIG. 7(a, b) is CsPbBr₃@SiO₂TEM and HRTEM images thereof; FIG. 8 shows CsPbBr₃@SiO₂EDS diagram.

From the XRD pattern of FIG. 6(a), it can be seen that 15 °, 21 °, 31 °, 33 °, 37 ° and 43 ° correspond to CsPbBr, respectively₃The peaks for the {100}, {110}, {200}, {210}, {211} and {220} crystal planes illustrate the resulting CsPbBr₃@SiO₂CsPbBr in (III)₃Is in cubic crystal form. Due to the SiO generated₂Is amorphous silicon, so its 2 theta peak is mixed with CsPbBr₃The {110} peak positions overlap and therefore do not show their characteristic peaks. Furthermore, CsPbBr₃@SiO₂The fluorescent material shows good fluorescent property, the half-peak width is 20nm, and bright green fluorescence is shown under ultraviolet and the like.

The generated CsPbBr can be seen from the TEM image of FIG. 7(a)₃Is uniformly coated on CsPbBr₃@SiO₂In (c), and the generated CsPbBr can be known from HRTEM (b) of FIG. 7₃Has obvious lattice stripes, which shows that the crystal structure is better than that of the prior SiO₂The coating structure is similar, but the synthesis time of the method is greatly shortened compared with that of the previous method by a plurality of hours, which shows that the method has strong competitiveness. In addition, it can be further confirmed from fig. 8 that the product produced is actually CsPbBr₃@SiO₂。

Example 4

sequentially adding 3 into the reaction tube0mg Cs₂CO₃35mg of lead stearate, 70mg of TBB, 5mL of octadecene and 260uL of APTES, adding a magnetic stirrer, finally placing the reaction tube in a reaction chamber of a microwave synthesizer, and reacting at 150 ℃ for 6min to obtain CsPbBr₃@SiO₂A perovskite nanocrystalline composite.

Example 5

adding 35mg of Cs into the reaction tube in sequence₂CO₃40mg of lead stearate, 75mg of TBB, 5mL of octadecene and 300uL of APTES, adding a magnetic stirrer, finally placing the reaction tube in a reaction chamber of a microwave synthesizer, and reacting at 160 ℃ for 6min to obtain CsPbBr₃@SiO₂A perovskite nanocrystalline composite.

Example 6

31mg of Cs were added to the reaction tube in sequence₂CO₃39.0mg of lead stearate, 72.5mg of TBB, 5mL of octadecene and 280uL of APTES, then adding a magnetic stirrer, finally placing the reaction tube in a reaction chamber of a microwave synthesizer, and reacting for 9min at 140 ℃ to obtain CsPbBr₃@SiO₂A perovskite nanocrystalline composite.

Claims

1.CsPbBr₃@SiO₂The microwave-assisted heating synthesis method of the perovskite nanocrystalline composite is characterized by comprising the following steps: adding Cs into the reaction tube in sequence₂CO₃Lead stearate, 1,3,5-tri (bromomethyl) benzene, octadecene and 3-aminopropyl triethoxysilane, adding a magnetic stirrer, placing the reaction tube in a reaction chamber of a microwave synthesizer, and reacting at 140 deg.C for 6min to obtain CsPbBr₃@SiO₂A perovskite nanocrystalline composite;

the Cs₂CO₃The ratio of the amount of lead stearate to the amount of 1,3,5-tris (bromomethyl) benzene to the amount of octadecene to 3-aminopropyltriethoxysilane was 32.4mg:38.7mg:71.6mg:5mL:0.28 mL。

2. The CsPbBr of claim 1₃@SiO₂The microwave-assisted heating synthesis method of the perovskite nanocrystalline composite is characterized by comprising the following steps: the rotation speed of the reaction is 1000-1400 rpm.

3. The CsPbBr of claim 2₃@SiO₂The microwave-assisted heating synthesis method of the perovskite nanocrystalline composite is characterized by comprising the following steps: the rotational speed of the reaction was 1200 rpm.

4. CsPbBr obtained according to any of the methods of claims 1 to 3₃@SiO₂A perovskite nanocrystalline composite.