Preparation method of flexible perovskite quantum dot film and application thereof

Abstract

The application belongs to the technical field of photoelectricity, and particularly relates to a preparation method of a flexible perovskite quantum dot composite film, which can be used for preparing a deep ultraviolet photoelectric detector. The principle of the application is that, in a PVDF crystallization process, DMF atmosphere is used to inhibit perovskite crystallization, perovskite is crystallized to form quantum dots in a secondary air annealing process, and the quantum dots are inlaid in the inside of PVDF, that is, perovskite quantum dots and PVDF are crystallized in steps, so that PVDF and perovskite are prevented from being crystallized at the same time, perovskite grains are prevented from growing, and it is difficult to form quantum dots. The flexible perovskite quantum dot film prepared by the application has excellent photoluminescence performance, chemical stability and mechanical stability. The application also adjusts the PVDF crystallinity and the perovskite quantum dot density through ultrasonic, so that higher photoluminescence efficiency is achieved.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic technology, specifically relating to a method for preparing a high-brightness, high-stability flexible perovskite quantum dot composite film in situ. This composite film can be used to prepare a deep ultraviolet photodetector. Background Technology

[0002] In recent years, perovskite quantum dots have attracted widespread attention due to their advantages over traditional rare-earth quantum dots, such as higher quantum efficiency, narrow emission wavelength, tunable bandgap, ease of fabrication, and low cost, showing excellent application prospects in displays, photovoltaic cells, and photodetectors. However, common perovskite quantum dot fabrication processes, such as hot-pouring and antisolvent methods, generate large amounts of waste liquid, causing significant pollution. Furthermore, during purification, ligand volatilization and the perovskite quantum dots' erosion by atmospheric oxygen and water vapor, as well as photothermal effects, lead to rapid deterioration and poor stability. In-situ fabrication of perovskite quantum dots within a parent material, forming an effective coating structure, is beneficial for improving their stability. Therefore, ensuring quantum dot quality during in-situ fabrication is crucial. Summary of the Invention

[0003] This invention is achieved through the following technical solution: A method for preparing a flexible perovskite quantum dot thin film specifically includes the following steps: (1) To prepare a perovskite precursor solution, lead halide and any one of methylamine halide, formamidine halide, cesium halide, and polymeric material are dissolved in a polar solvent, ultrasonically treated, and then allowed to stand. The polymeric material used is PVDF, PVDF-trfe, or a mixture thereof. (2) Use a pipette to take the precursor solution onto a flat glass slide substrate and spin-coat it to obtain a liquid film; (3) Transfer the glass to the baking plate, cover the sample with a glass dish for annealing, PVDF crystallizes, and the liquid film is transformed into a white film; (4) Transfer the film along with the glass dish as a whole, cool it to room temperature and remove the glass dish, then place the film in the air environment. The perovskite quantum dots crystallize inside the PVDF to form a perovskite quantum dot / PVDF composite film. Peel the quantum dot / PVDF composite film from the glass substrate in deionized water to obtain a flexible perovskite quantum dot film.

[0004] If the above-mentioned flexible perovskite quantum dot thin film is used to prepare a photodetector, the following steps are also included: (5) Spin-coating SnO2 colloid onto an ITO glass substrate, annealing and drying, then taking FA 0.85 Cs 0.15The PbI3 DMF / DMSO solution was spin-coated and then annealed, followed by the preparation of a carbon electrode using a blade coating method. The electrode was then annealed until the carbon slurry was dried to prepare the FA. 0.85 Cs 0.15 PbI3 perovskite solar cells.

[0005] (6) The stripped quantum dot / PVDF composite film is attached to the FA 0.85 Cs 0.15 A self-powered perovskite photodetector was fabricated by fixing the incident side of a PbI3 perovskite solar cell with adhesive.

[0006] The polar solvent used in step (1) is any one of DMF and DMSO or a mixture thereof.

[0007] The lead halide mentioned in step (1) is one of lead bromide, lead chloride, lead iodide, or a mixture thereof.

[0008] The molar ratio of lead halide to any one of methylamine halide, formamidine halide, or cesium halide in the solution used in step (1) is between 0.5 and 2, and the molar concentration is between 0.008 and 0.08 mol / L.

[0009] Preferably, the ultrasound time in step (1) is half an hour.

[0010] Preferably, in step (1), the molar ratio of lead halide to methylamine halide, formamidine halide and cesium halide is 1, and the molar concentration is 0.06 mol / L.

[0011] Preferably, the PVDF concentration in step (1) is 160 g / L.

[0012] Preferably, in step (3), the film annealing temperature is 50°C and the annealing time is 3 minutes.

[0013] Preferably, in step (4), the film cooling time is 90-120s and the placement time is 2h.

[0014] Preferably, in step (5), the SnO2 colloid mass fraction is 5%, the rotation speed is 4000 rpm, the annealing temperature is 170°C, and the annealing time is 30 minutes.

[0015] Preferably, the perovskite solution in step (5) has a molar mass concentration of 1.45 mol / L, a rotation speed of 3000 rpm, an annealing temperature of 150°C, and an annealing time of 15 minutes.

[0016] Preferably, the annealing temperature of the carbon electrode in step (5) is 170°C and the annealing time is 30 minutes.

[0017] The flexible perovskite quantum dot film prepared by this invention has excellent photoluminescence properties, as well as excellent chemical and mechanical stability, providing a simple and universal manufacturing process for producing perovskite quantum dot films.

[0018] This invention proposes a simple, low-cost, and highly reproducible method for preparing perovskite quantum dot / PVDF composite films. The principle is to use a DMF atmosphere to suppress perovskite crystallization during the PVDF crystallization process. The perovskite crystallizes into quantum dots during the secondary air annealing process and is embedded inside the PVDF. That is, the perovskite quantum dots and PVDF crystallize in a stepwise manner, avoiding the simultaneous crystallization of PVDF and perovskite, which would cause the perovskite grains to grow and make it difficult to form quantum dots.

[0019] This invention also achieves higher photoluminescence efficiency by adjusting the crystallinity of PVDF and the density of perovskite quantum dots using ultrasound.

[0020] The present invention also utilizes perovskite quantum dot / PVDF composite thin films to prepare a deep ultraviolet photodetector, as specifically shown in Example 5. Attached Figure Description

[0021] Figure 1 This is an image of the perovskite quantum dot film prepared in Example 1 under a UV lamp.

[0022] Figure 2 The image shows the X-ray diffraction pattern of the perovskite quantum dot film prepared in Example 1.

[0023] Figure 3 The image shows the photoluminescence spectrum of the perovskite quantum dot film prepared in Example 1.

[0024] Figure 4 The photoluminescence spectrum of the perovskite quantum dot film prepared in Example 2 is shown.

[0025] Figure 5 This is an image of the perovskite quantum dot film prepared in Example 3 under ultraviolet light.

[0026] Figure 6 The current-voltage curves of the deep ultraviolet detector prepared in Example 4 under dark conditions and 275nm deep ultraviolet illumination are shown. Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention. Example

[0028] 0.06753 g PbBr2, 0.01645 g MABr (ammonium bromide), and 0.42 g PVDF were dissolved in 2.5 μL of DMF and stirred until completely dissolved. 160 μL of the solution was added dropwise to a 2×2 cm glass slide and spin-coated at 1000 rpm for 30 seconds. The baking plate was set to 50 °C. The spin-coated sample was transferred to the baking plate, covered with a glass dish, and heated for 150 seconds. The sample, along with the glass dish, was then transferred to a low-temperature environment and cooled for 90 seconds. The glass dish was removed, and the perovskite film rapidly crystallized, yielding a perovskite quantum dot / PVDF composite film, known as Sample 1. Sample 2 was prepared under the same conditions, except that it was not covered with a glass dish during annealing on the baking plate.

[0029] The results are shown in the figure. Figure 1-3 These are fluorescence images, photoluminescence spectra, and XRD patterns of perovskite quantum dot films. XRD analysis reveals that both Sample 1 and Sample 2 exhibit a perovskite peak at 15° and a PVDF peak at 22°, indicating that both formed a perovskite / PVDF coated structure. However, only the sample crystallized under DMF atmosphere (covered with a glass dish) formed quantum dots and showed significant fluorescence. Example

[0030] 0.06753 g PbBr2, 0.01645 g MABr, and 0.42 g PVDF were dissolved in 2.5 μL of DMF and stirred until completely dissolved. The precursor solution was then sonicated for a period of time. 160 μL of the solution was dropped onto a 2×2 cm glass slide and spin-coated at 1000 rpm for 30 seconds. The baking plate was set to 50 °C. The spin-coated sample was transferred to the baking plate, covered with a glass dish, and heated for 150 seconds. The sample and the glass dish were then transferred to a low-temperature environment and cooled for 90 seconds. The glass dish was then removed, and the perovskite film rapidly crystallized to obtain a perovskite quantum dot film.

[0031] The ultrasound durations were 0 minutes, 5 minutes, 15 minutes, and 30 minutes, respectively. Figure 4 Photoluminescence spectra revealed that the photoluminescence of perovskite quantum dot films first decreased and then increased with increasing sonication time, with the perovskite quantum dot films prepared from precursors that were sonicated for 30 minutes exhibiting the best luminescence performance. Example

[0032] 0.03360 g PbBr2, 0.007344 mmol A-site bromide, and 0.42 g PVDF were dissolved in 2.5 μL DMF and stirred until completely dissolved. The precursor solution was then sonicated for half an hour. 160 μL of the solution was dropped onto a 2×2 cm glass slide and spin-coated at 1000 rpm for 30 seconds. The baking plate was set to 50 °C. The spin-coated sample was transferred to the baking plate, covered with a glass dish, and heated for 150 seconds. The sample and the glass dish were then transferred to a low-temperature environment and cooled for 90 seconds. The glass dish was then removed, and the perovskite film rapidly crystallized to obtain a perovskite quantum dot film.

[0033] The A-site bromide salts described are FABr, MABr, and CsBr, respectively. Figure 5 As shown, both exhibited obvious fluorescence under ultraviolet light irradiation, indicating that this method is universal and can be used to prepare FAPbBr3 and CsPbBr3 quantum dot films. Example

[0034] Deep ultraviolet detector fabrication process MAPbBr3 perovskite quantum dot films were prepared using the method described above and then exfoliated in deionized water.

[0035] A 5% SnO2 colloid was spin-coated onto a purchased ITO substrate at 4000 rpm for 30 seconds, followed by annealing at 170°C for 30 minutes. Then, 60 μL of 1.45 mol / L FA was taken. 0.85 Cs 0.15 A PbI3 DMF / DMSO solution (9:1 ratio) was spin-coated at 3000 rpm for 30 seconds, then annealed at 150°C for 15 minutes. Finally, a coating with an area of ​​0.12 cm² was prepared using a doctor blade coating method. 2 Carbon electrode, annealed at 150℃ for 30 minutes, to prepare FA 0.85 Cs 0.15 PbI3 perovskite photovoltaic cells.

[0036] A perovskite quantum dot / PVDF composite film was attached to the back of a photovoltaic perovskite photodetector glass to serve as a deep ultraviolet light conversion window, designated as device 1. Device 2 was then fabricated using the same method, with the difference being that the precursor for device 1 was not ultrasonically treated during the fabrication of the perovskite quantum dot film, while the perovskite quantum dot film for device 2 underwent ultrasonic treatment for 30 minutes. A wavelength of 275 nm and an intensity of 1.5 mW / cm² were used. 2 The device is tested for photoelectric response to deep ultraviolet light when illuminated from the back. Figure 6 The IV curves for the photodetector under 275nm illumination and in the dark state reveal its sensitive response to deep ultraviolet light, with a maximum on / off ratio reaching 10. 4Furthermore, the ultrasonic treatment resulted in a threefold increase in the response of the thin-film device to deep ultraviolet light, demonstrating that ultrasonic treatment can improve the conversion efficiency of perovskite quantum dot films to deep ultraviolet light.

[0037] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a flexible perovskite quantum dot thin film, characterized in that, Includes the following steps: (1) To prepare a perovskite precursor solution, lead halide and any one of methylamine halide, formamidine halide, cesium halide, and polymeric material are dissolved in a polar solvent, ultrasonically treated, and then allowed to stand. The polymeric material used is PVDF, PVDF-trfe, or a mixture thereof. (2) Use a pipette to take the precursor solution onto a flat glass slide substrate and spin-coat it to obtain a liquid film; (3) Transfer the glass to the baking plate, cover the sample with a glass dish for annealing, PVDF crystallizes, and the liquid film is transformed into a white film; (4) Transfer the film along with the glass dish as a whole, cool it to room temperature and remove the glass dish, then place the film in the air environment. The perovskite quantum dots crystallize inside the PVDF to form a perovskite quantum dot / PVDF composite film. Peel the quantum dot / PVDF composite film from the glass substrate in deionized water to obtain a flexible perovskite quantum dot film.

2. The preparation method according to claim 1, characterized in that, The polar solvent used in step (1) is one of DMF, DMSO or a mixture thereof.

3. The preparation method according to claim 1, characterized in that, The lead halide mentioned in step (1) is one of lead bromide, lead chloride, lead iodide, or a mixture thereof.

4. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of lead halide to methylamine halide, formamidine halide and cesium halide in the solution is between 0.5 and 2, and the molar concentration of lead halide is between 0.008 and 0.08 mol / L.

5. The preparation method according to claim 1, characterized in that, The ultrasound time in step (1) is half an hour.

6. The preparation method according to claim 1, characterized in that, In step (3), the film annealing temperature is 50°C and the annealing time is 3 minutes.

7. The preparation method according to claim 1, characterized in that, In step (4), the film cooling time is 90-120s and the placement time is 2h.

8. A method for fabricating a photodetector, characterized in that, Includes the following steps: a. To prepare a perovskite precursor solution, lead halide and any one of methylamine halide, formamidine halide, cesium halide, or a polymeric material are dissolved in a polar solvent, ultrasonically treated, and then allowed to stand. The polymeric material used is PVDF, PVDF-trfe, or a mixture thereof. b. Use a pipette to take the precursor solution onto a flat glass slide substrate and spin-coat it to obtain a liquid film; c. Transfer the glass to a baking plate, cover the sample with a glass dish for annealing, PVDF crystallizes, and the liquid film transforms into a white film; d. Transfer the film along with the glass dish as a whole, cool it to room temperature, remove the glass dish, and then place the film in the air environment. The perovskite quantum dots crystallize inside the PVDF to form a perovskite quantum dot / PVDF composite film. Peel the quantum dot / PVDF composite film from the glass substrate in deionized water to obtain a flexible perovskite quantum dot film. e. Spin-coat SnO2 colloid onto an ITO glass substrate, anneal and dry, then take FA... 0.85 Cs 0.15 A PbI3 DMF / DMSO solution was spin-coated and annealed, then a carbon electrode was prepared by a blade coating method, followed by annealing until the carbon slurry was dried to prepare a FA electrode. 0.85 Cs 0.15 PbI3 perovskite solar cells; f. Attach the peeled quantum dot / PVDF composite film to FA 0.85 Cs 0.15 A self-powered perovskite photodetector was fabricated by fixing the incident side of a PbI3 perovskite solar cell with adhesive.

9. The method according to claim 8, characterized in that, In step e, the SnO2 colloid mass fraction is 5%, the rotation speed is 4000 rpm, the annealing temperature is 170℃, and the annealing time is 30 minutes.

10. The method according to claim 8, characterized in that, In step e, the concentration of the perovskite solution is 1.45 mol / L, the rotation speed is 3000 rpm, the annealing temperature is 150℃, and the annealing time is 15 minutes.

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