Hydrogel confinement CsPbBr3 (at) CsPb2Br5 core-shell structure perovskite nanocrystalline fluorescent film and preparation method and application thereof

Abstract

The invention belongs to the field of preparation of flexible perovskite fluorescent films, and particularly relates to a hydrogel confinement CsPbBr3-atCsPb2Br5 core-shell structure perovskite nanocrystalline fluorescent film as well as a preparation method and application of the hydrogel confinement CsPbBr3-atCsPb2Br5 core-shell structure perovskite nanocrystalline fluorescent film. The flexible perovskite fluorescent gel with the CsPbBr3-coated CsPb2Br5 core-shell structure is prepared through in-situ freeze thawing by using pure water as a solvent and using 4-dodecylbenzene sulfonic acid as a ligand, the obtained perovskite fluorescent gel has strong green fluorescence and high color purity, the emission wavelength of the perovskite fluorescent gel is located at 522 nm, and the half-peak width is as narrow as 18 nm. And the X-ray imaging device has better imaging resolution capability when being applied to X-ray imaging. Compared with other organic fluorescent gels, the preparation method is simpler, more convenient, environment-friendly and pollution-free. The method provided by the invention provides a new way for green preparation of the efficient and flexible perovskite fluorescent gel.

Description

Technical Field

[0001] The present invention relates to the field of preparation of flexible halide perovskite nanocrystalline films, and in particular to a hydrogel confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystalline fluorescent film and a preparation method and application thereof. Background Art

[0002] Metal halide perovskite (MHP) has the advantages of high photoluminescence quantum yield, tunable emission wavelength, and high color purity, and has broad application prospects in light-emitting diodes, bioimaging, sensors, etc.

[0003] However, the fluorescence intensity and fluorescence quantum yield of the current perovskite fluorescent film are relatively low, and the luminescence stability is relatively poor. Although the perovskite fluorescent film obtained by polymer coating can improve its stability to a certain extent, in order to promote the dissolution of the perovskite precursor and the polymer during the preparation process, toxic and flammable organic solvents are inevitably used.

[0004] As a functional polymer material rich in water, hydrogel has good biocompatibility and mechanical properties and is widely used in flexible electronic devices and biomedicine. Compared with the polymer-coated perovskite fluorescent film, the flexible perovskite nanocrystal fluorescent hydrogel film obtained by coupling hydrogel with perovskite nanocrystals has improved flexibility and stretchability. In addition, the viscous gel solution can also limit the migration of perovskite nanoparticles, making them evenly dispersed and improving the luminescence uniformity of the fluorescent film.

[0005] It is worth noting that there is currently little research on the in situ green preparation of flexible perovskite fluorescent gel films in aqueous solution. Most of the preparation methods involve mixing the prepared nanocrystal colloidal solution with the gel solution. The process is relatively complicated and the fluorescence intensity and fluorescence quantum yield of the obtained gel film are still low. Summary of the invention

[0006] The present invention overcomes the shortcomings of the prior art and provides a method for preparing a hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film. The method of the present invention is to prepare an efficient and flexible perovskite nanocrystal fluorescent gel film by in-situ green freeze-thaw in an aqueous solution.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film, comprising the following steps: 1) Dissolve polyvinyl alcohol (PVA) and 4-dodecylbenzenesulfonic acid (DBSA) in deionized water, and obtain a uniformly dispersed solution by heating and stirring; 2) Take polyvinyl pyrrolidone (PVP) and dissolve it in deionized water, then add it to the solution obtained in step 1), stir and set aside; 3) Add cesium bromide (CsBr) and lead bromide (PbBr2) to the solution obtained in step 2) and stir until uniformly dispersed; 4) The solution obtained in step 3) is poured into a culture dish and placed in an ultra-low temperature refrigerator. After multiple freeze-thaw cycles, a CsPbBr3@CsPb2Br5 core-shell structured perovskite nanocrystal fluorescent film is finally obtained.

[0008] The present invention is prepared in pure water solution, and a perovskite fluorescent gel film is obtained by in-situ reaction and freeze-thaw cycle. A perovskite fluorescent gel film with a core of CsPbBr3 and a shell of CsPb2Br5 core-shell structure is prepared by using amphiphilic ligand 4-dodecylbenzenesulfonic acid (DBSA), and finally in an ultra-low temperature refrigerator, freeze-thaw cycles are used to make it gel.

[0009] As a further limitation of the technical solution of the present invention, in step 1), the mass volume ratio of polyvinyl alcohol, 4-dodecylbenzenesulfonic acid and deionized water is 2-4 g: 0.1-0.5 g: 20-50 ml.

[0010] As a further limitation of the technical solution of the present invention, it is characterized in that the heating temperature in step 1) is 90°C.

[0011] As a further limitation of the technical solution of the present invention, it is characterized in that in step 2), the mass volume ratio of polyvinyl pyrrolidone to deionized water is 0.5-1g:5-10ml; the mass ratio of polyvinyl pyrrolidone to polyvinyl alcohol is 1-2:4-8.

[0012] As a further limitation of the technical solution of the present invention, it is characterized in that, in step 3), the molar ratio of cesium bromide to lead bromide is 1:1; and the mass ratio of cesium bromide to polyvinyl pyrrolidone is 11:50-100.

[0013] The present invention also provides a hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film obtained by the above preparation method.

[0014] In addition, the present invention also provides the application of the hydrogel confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film in X-ray imaging. The application of the film in the field of X-ray imaging has good imaging capability.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention develops a fluorescent film using water as a solvent. Compared with other fluorescent films prepared using toxic organic solvents, the preparation process using water as a solvent is environmentally friendly and pollution-free.

[0016] The present invention prepares a flexible perovskite nanocrystal fluorescent gel film with a CsPbBr3@CsPb2Br5 core-shell structure by an in-situ green freeze-thaw method, and the preparation method is efficient and simple.

[0017] Compared with other fluorescent hydrogel films, the CsPbBr3@CsPb2Br5 flexible perovskite nanocrystal fluorescent gel film prepared by the present invention has high fluorescence intensity and good color purity.

[0018] The CsPbBr3@CsPb2Br5 flexible perovskite nanocrystal fluorescent gel film prepared by the present invention has excellent performance when applied to X-ray imaging, and expands the application of perovskite fluorescent films in biological imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A transmission electron microscope (TEM) image showing the CsPbBr3@CsPb2Br5 flexible perovskite nanocrystal fluorescent gel film of the present invention with a scale of 5 nm.

[0020] Figure 2 A scanning electron microscope (SEM) image of the CsPbBr3@CsPb2Br5 flexible perovskite nanocrystal fluorescent gel film of the present invention is shown.

[0021] Figure 3 The photoluminescence (PL) spectrum and ultraviolet-visible absorption (Abs) spectrum of the CsPbBr3@CsPb2Br5 flexible perovskite nanocrystal fluorescent gel film of the present invention are shown.

[0022] Figure 4 The X-ray diffraction (XRD) spectrum of the CsPbBr3@CsPb2Br5 flexible perovskite nanocrystal fluorescent gel film of the present invention is shown.

[0023] Figure 5 An X-ray imaging diagram of the CsPbBr3@CsPb2Br5 flexible perovskite nanocrystal fluorescent gel film of the present invention is shown. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific embodiments. Example 1

[0025] A method for preparing a flexible perovskite fluorescent gel film with a CsPbBr3@CsPb2Br5 core-shell structure comprises the following steps: A. Take 3g PVA and 0.12g DBSA and dissolve them in 47ml deionized water. Heat at 90℃ and stir to obtain a uniformly dissolved solution.

[0026] B. Take 0.5g PVP and dissolve it in 5ml deionized water, then add it to the solution obtained in step A and continue stirring for 30 min.

[0027] C. Add 0.5 mmol CsBr and 0.5 mmol PbBr2 to the solution obtained in step B and stir until uniformly dispersed.

[0028] D. Finally, the solution obtained in step C was poured into a culture dish and placed in a low-temperature refrigerator. After three freeze-thaw cycles (freezing for 12 h and thawing for 2 h), the CsPbBr3@CsPb2Br5 fluorescent gel film was finally obtained. Example 2

[0029] A method for preparing a flexible perovskite fluorescent gel film with a CsPbBr3@CsPb2Br5 core-shell structure comprises the following steps: A. Dissolve 3 g PVA and 0.12 g DBSA in 40 ml deionized water, and heat at 90°C and stir to obtain a uniform solution. B. Take 0.5g PVP and dissolve it in 5ml deionized water, then add it to the solution obtained in step A and continue stirring for 30 min.

[0030] C. Add 0.5 mmol CsBr and 0.5 mmol PbBr2 to the solution obtained in step B and stir until uniformly dispersed.

[0031] D. Finally, the solution obtained in step C was poured into a culture dish and placed in a low-temperature refrigerator. After three freeze-thaw cycles (freezing for 12 h and thawing for 2 h), the CsPbBr3@CsPb2Br5 fluorescent gel film was finally obtained. Example 3

[0032] A method for preparing a flexible perovskite fluorescent gel film with a CsPbBr3@CsPb2Br5 core-shell structure comprises the following steps: A. Dissolve 3 g PVA and 0.12 g DBSA in 34 ml deionized water, and heat at 90 °C and stir to obtain a uniform solution. B. Take 0.5g PVP and dissolve it in 5ml deionized water, then add it to the solution obtained in step A and continue stirring for 30 min.

[0033] C. Add 0.5 mmol CsBr and 0.5 mmol PbBr2 to the solution obtained in step B and stir until uniformly dispersed.

[0034] D. Finally, the solution obtained in step C was poured into a culture dish and placed in a low-temperature refrigerator. After three freeze-thaw cycles (freezing for 12 h and thawing for 2 h), the CsPbBr3@CsPb2Br5 fluorescent gel film was finally obtained. Example 4

[0035] A method for preparing a flexible perovskite fluorescent gel film with a CsPbBr3@CsPb2Br5 core-shell structure comprises the following steps: A. Dissolve 3 g PVA and 0.12 g DBSA in 30 ml deionized water, and heat at 90°C and stir to obtain a uniform solution. B. Take 0.5g PVP and dissolve it in 5ml deionized water, then add it to the solution obtained in step A and continue stirring for 30 min.

[0036] C. Add 0.5 mmol CsBr and 0.5 mmol PbBr2 to the solution obtained in step B and stir until uniformly dispersed.

[0037] D. Finally, the solution obtained in step C was poured into a culture dish and placed in a low-temperature refrigerator. After three freeze-thaw cycles (freezing for 12 h and thawing for 2 h), the CsPbBr3@CsPb2Br5 fluorescent gel film was finally obtained. Example 5

[0038] A method for preparing a flexible perovskite fluorescent gel film with a CsPbBr3@CsPb2Br5 core-shell structure comprises the following steps: A. Take 3g PVA and 0.12g DBSA and dissolve them in 27ml deionized water. Heat at 90℃ and stir to obtain a uniformly dissolved solution.

[0039] B. Take 0.5g PVP and dissolve it in 5ml deionized water, then add it to the solution obtained in step A and continue stirring for 30 min.

[0040] C. Add 0.5 mmol CsBr and 0.5 mmol PbBr2 to the solution obtained in step B and stir until uniformly dispersed.

[0041] D. Finally, the solution obtained in step C was poured into a culture dish and placed in a low-temperature refrigerator. After three freeze-thaw cycles (freezing for 12 h and thawing for 2 h), a CsPbBr3@CsPb2Br5 fluorescent gel film was finally obtained. Example 6

[0042] A method for preparing a flexible perovskite fluorescent gel film with a CsPbBr3@CsPb2Br5 core-shell structure comprises the following steps: A. Dissolve 3 g PVA and 0.12 g DBSA in 24 ml deionized water, and heat at 90°C and stir to obtain a uniform solution. B. Take 0.5g PVP and dissolve it in 5ml deionized water, then add it to the solution obtained in step A) and continue stirring for 30 minutes.

[0043] C. Add 0.5 mmol CsBr and 0.5 mmol PbBr2 to the solution obtained in B) and stir until uniformly dispersed.

[0044] D. Finally, the solution obtained in step C was poured into a culture dish and placed in a low-temperature refrigerator. After three freeze-thaw cycles (freezing for 12 h and thawing for 2 h), the CsPbBr3@CsPb2Br5 fluorescent gel film was finally obtained.

[0045] Test analysis: Sample characterization: Take an appropriate amount of the solution obtained in step C of Example 5 and apply it to a film, freeze-thaw cycle to gel, and then dry it for TEM characterization. Take an appropriate amount of the product obtained in Example 5 D and freeze-dry it for 48 hours for SEM characterization and performance testing in X-ray imaging applications. Take an appropriate amount of the product obtained in Example 5 D and directly perform XRD, Abs and PL characterization.

[0046] Attached Figure 1 TEM image of the flexible perovskite nanocrystal fluorescent gel film of Example 5 of the present invention. Figure 2 The SEM image of the flexible perovskite nanocrystal fluorescent gel film of Example 5 of the present invention is shown. Figure 3 The PL spectrum and Abs spectrum of the flexible perovskite nanocrystal fluorescent gel film of Example 5 of the present invention are shown. Figure 4 The XRD spectrum of the flexible perovskite nanocrystal fluorescent gel film of Example 5 of the present invention is shown. Figure 5 An X-ray imaging diagram of the flexible perovskite nanocrystal fluorescent gel film according to Example 5 of the present invention.

[0047] 1. Structural characterization Based on the above test results, it can be seen from the TEM and SEM images that the method of the present invention uses water as a solvent to prepare a porous network hydrogel-confined CsPbBr3@CsPb2Br5 flexible perovskite fluorescent gel film by in situ freeze-thaw. The XRD spectrum proves that this flexible perovskite fluorescent film material has a CsPb2Br5 shell phase, and the internal perovskite nanocrystals are a core-shell structure.

[0048] 2. Characterization of fluorescence properties It can be concluded from the fluorescence spectrum (PL) and UV-visible absorption spectrum (Abs) that the prepared flexible fluorescent gel film has strong green fluorescence, the emission wavelength is at 522 nm, and the half-peak width is as narrow as 18 nm, proving that it has high color purity.

[0049] (III) X-ray imaging performance test The prepared CsPbBr3@CsPb2Br5 flexible perovskite fluorescent gel film was applied in X-ray imaging. By comparing the X-ray imaging image with the standard card, it was found that it had good imaging resolution.

[0050] The preparation method of the present invention directly prepares a flexible perovskite fluorescent gel film with a CsPbBr3@CsPb2Br5 core-shell structure by in-situ freeze-thawing in an aqueous solution. Compared with the preparation of other fluorescent gel films, the preparation method is simpler and uses water as a solvent, which is more environmentally friendly and pollution-free.

[0051] The above-mentioned implementation mode is only used to illustrate the content of the present invention, but it is not a limitation of the present invention. Relevant technical personnel in the field can also make corresponding adjustments and modifications without departing from the scope of the present invention. Therefore, all technical solutions formed by equivalent replacement or equivalent modification belong to the protection scope of the present invention.

Claims

1. A method for preparing a hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film, characterized in that: The following steps are involved: 1) Dissolve polyvinyl alcohol and 4-dodecylbenzenesulfonic acid in deionized water, and obtain a uniformly dispersed solution by heating and stirring; 2) dissolving polyvinyl pyrrolidone in deionized water by stirring, and then adding it to the solution obtained in step 1), stirring and setting aside; 3) adding cesium bromide and lead bromide to the solution obtained in step 2) and stirring until the solution is evenly dispersed; 4) The solution obtained in step 3) is poured into a culture dish and placed in an ultra-low temperature refrigerator. After multiple freeze-thaw cycles, a CsPbBr3@CsPb2Br5 core-shell structured perovskite nanocrystal fluorescent film is finally obtained.

2. The method for preparing a hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film according to claim 1, characterized in that: In step 1), the mass volume ratio of polyvinyl alcohol, 4-dodecylbenzenesulfonic acid and deionized water is 2-4g:0.1-0.5g:20-50ml.

3. The method for preparing a hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film according to claim 1, characterized in that: The heating temperature in step 1) is 90°C.

4. The method for preparing a hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film according to claim 1, characterized in that: In step 2), the mass volume ratio of polyvinyl pyrrolidone to deionized water is 0.5-1 g: 5-10 ml; the mass ratio of polyvinyl pyrrolidone to polyvinyl alcohol is 1-2: 4-8.

5. The method for preparing a hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film according to claim 1, characterized in that: In step 3), the molar ratio of cesium bromide to lead bromide is 1:1; the mass ratio of cesium bromide to polyvinyl pyrrolidone is 11:50-100.

6. A hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structured perovskite nanocrystal fluorescent film obtained by the preparation method according to any one of claims 1 to 5.

7. Application of the hydrogel-confined CsPbBr3@CsPb2Br5 core-shell structure perovskite nanocrystal fluorescent film according to claim 6 in X-ray imaging.

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