A preparation method of a high-voltage electric field polarized perovskite quantum dot self-assembled wafer-level film capable of being peeled off reversibly

Abstract

The present application relates to the field of perovskite thin film preparation, and relates to a preparation method of high-voltage electric field polarized perovskite quantum dot self-assembly deposition wafer-level thin film which can be peeled off reversely. Different from the traditional electrodeposition method, the method is to polarize perovskite quantum dots by applying high-voltage electric field, without adding electrolyte salt or using cyclic voltammetry to control the deposition time to prepare wafer-level thin film. The present application makes perovskite lattice distorted by high-voltage electric field polarization, promotes the ordered arrangement of methylammonium ions, and the short chain makes the exposed active sites on the surface of quantum dots more, the van der Waals force is enhanced, in addition, the low desorption energy of short chain ligand can promote the rapid and uniform spreading of perovskite quantum dots. The method realizes the growth of wafer-level thin film by the synergistic effect of external high-voltage electric field polarization force, intermolecular interaction force and van der Waals force between molecules and substrate. And by applying reverse voltage, the thin film can be peeled off to recover the material, which provides a new path for industrialized production of large-area perovskite quantum dot thin film.

Description

Technical Field

[0001] This invention relates to the field of perovskite thin film preparation technology, and specifically to a method for preparing wafer-level thin films by high-voltage electric field polarized perovskite quantum dots that can be reverse-exfoliated. Background Technology

[0002] In recent years, perovskite materials have rapidly become a globally popular material due to their excellent photoelectric properties, experiencing a near-vertical rise in popularity. Based on the ABX3 crystal structure, the A, B, and X sites of perovskite materials allow for flexible substitution of elements, enabling tunable band gap energy to adapt to various photoelectric applications. They possess extremely high light absorption coefficients, long carrier diffusion lengths and lifetimes, and excellent charge transport efficiency, which are the core reasons for their outstanding photoelectric conversion performance. Therefore, perovskite materials have numerous applications in solar cells, photodetectors, and photosynapses.

[0003] Currently, most perovskite thin films are too small to meet the demands of industrial production and commercialization. Therefore, wafer-level perovskite film fabrication has become a core issue in the field of perovskite materials. Furthermore, ensuring high-quality perovskite films is crucial during wafer-level film preparation. Current reports on methods for preparing perovskite thin films mainly fall into four categories: 1) spin-coating derivative processes, including rapid crystallization and vacuum flash solution treatment; 2) roll-to-roll compatible printing technologies, encompassing inkjet printing, slot extrusion coating, blade coating, and spray coating; 3) vapor-assisted deposition; and 4) soft capping deposition. However, these methods still suffer from problems such as low film quality, low material utilization, and high equipment complexity.

[0004] Spin-coating rapid crystallization remains a common method for preparing perovskite thin films in the laboratory due to its simple operation and intuitive parameters; however, its liquid loss during spin-coating results in a material utilization rate of less than 1%. While blade coating can improve raw material utilization, it is limited by solution shear instability, often resulting in streaks in the film. Slit extrusion, inkjet printing, and spray coating technologies offer advantages of roll-to-roll compatibility and high utilization; however, the coupled control of multiphase flow fields and evaporation kinetics is complex. Vapor-assisted deposition produces better film uniformity than spin-coating, but has a higher rate of raw material waste. Soft capping deposition can obtain dense and uniform perovskite layers through template transfer, but it requires prolonged substrate heating in the early stages, significantly increasing energy consumption and hindering the concept of low-temperature green manufacturing. Traditional electrodeposition methods can achieve uniform growth of small-area films through electric field forces, but the operation is complex, requiring the addition of electrolyte salts or cyclic voltammetry for deposition, and faces challenges such as the inability to achieve large-area wafer-level film preparation and the inability to recycle raw materials.

[0005] Compared to traditional perovskite thin film preparation methods, the high-voltage electric field polarized perovskite quantum dot self-assembly deposition method has advantages such as room temperature operation, wafer-level fabrication, high film quality, lower cost, and high raw material utilization. This invention aims to provide a wafer-level production method with a simple fabrication process that facilitates industrialization and is recyclable, enabling green and sustainable development of thin film high-voltage electric field polarized perovskite quantum dot self-assembly deposition. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing wafer-level thin films by high-voltage electric field polarized perovskite quantum dot self-assembly deposition with reverse peeling capability. This invention enables the preparation of wafer-level perovskite quantum dot thin films, and allows control of the film thickness by adjusting the voltage, solution concentration, and energizing time during the high-voltage electric field polarized perovskite quantum dot self-assembly deposition. Furthermore, film peeling is achieved by applying a reverse voltage.

[0007] The purpose of this invention is to provide a method for preparing a wafer-level thin film of high-voltage electric field polarized perovskite quantum dots that can be reverse-exfoliated, comprising the following steps: S1. Provide a conductive substrate; S2. Add the perovskite quantum dot material MAPbBr3 to a solvent and dissolve it to obtain an electrolyte; S3. Connect the conductive substrate to an external power source and place it in the electrolyte. Adjust the voltage of the external power source and control the high-voltage electric field to polarize the self-assembly deposition time of the perovskite quantum dots. This will deposit a perovskite quantum dot film on the conductive substrate, ultimately obtaining a wafer-level film.

[0008] In some specific embodiments of the present invention, in step S1, the conductive substrate needs to be cleaned, as detailed below: Step S11: After ultrasonically cleaning the conductive substrate with acetone, ethanol and deionized water in an ultrasonic cleaner for 15-20 minutes, place it in an oven at 80-90 ℃ for 50-60 minutes and set aside for use. Step S12: Treat the dried conductive substrate with ultraviolet ozone for 10-15 minutes.

[0009] Furthermore, the conductive substrate is used as both the anode and cathode.

[0010] Furthermore, the negative and positive electrodes are arranged face-to-face and parallel, with a distance of 18-20 mm between them.

[0011] In some specific embodiments of the present invention, the conductive substrate includes a rigid conductive substrate or a flexible conductive substrate.

[0012] In some specific embodiments of the present invention, the rigid conductive substrate is one of FTO conductive glass or ITO conductive glass; the flexible conductive substrate is a PET conductive film.

[0013] In some specific embodiments of the present invention, the perovskite quantum dot material MAPbBr3 is prepared by the following method: A PbBr2 precursor solution and an MA precursor solution are provided; PbBr2 precursor solution was added to an organic solvent to obtain a mixture; MA precursor solution was added and stirred for 5-10 minutes to obtain PNCs; then an organic solvent was added and a first centrifugation was performed to remove unreacted precursors to obtain precipitate. The obtained precipitate was dispersed in a mixed solvent and purified by a second centrifugation to obtain the perovskite quantum dot material MAPbBr3.

[0014] In some specific embodiments of the present invention, the concentration of the PbBr2 precursor in the mixture is 0.28~0.3 mmol / ml; The organic solvent includes one or more of toluene, acetonitrile, butylamine, propionic acid, and n-hexane; The first centrifugation was performed at a speed of 3800~4000 r / min for 3~4 min.

[0015] In some specific embodiments of the present invention, the mixed solvent includes toluene and acetonitrile, wherein the volume ratio of toluene to acetonitrile is (7:3) to (8:2). In some specific embodiments of the present invention, the concentration of perovskite quantum dot material MAPbBr3 in the electrolyte is 2.5~3 mg / mL.

[0016] In some specific embodiments of the present invention, the external power supply is a DC power supply.

[0017] In some specific embodiments of the present invention, the voltage adjustment range of the external power supply is 0~200 V.

[0018] In some specific embodiments of the present invention, the method for peeling off the self-assembled wafer-level thin film of high-voltage electric field polarized perovskite quantum dots that can be peeled off in reverse includes the following steps: Provides a conductive substrate and a well-deposited high-voltage electric field polarized perovskite quantum dot self-assembly deposition wafer-level thin film; Toluene and acetonitrile are mixed to obtain an electrolyte. The conductive substrate and the high-voltage electric field polarized perovskite quantum dot self-assembled deposition wafer-level thin film are placed in the electrolyte and connected to an external power source. By applying a reverse voltage of 190~200 V to the conductive substrate, adjusting the external voltage and controlling the time to 15~20 min, the reverse peeling of the film can be achieved.

[0019] The beneficial effects of this invention are: This invention utilizes a high-voltage electric field to polarize perovskite quantum dots to achieve wafer-level thin film self-assembly deposition. The fabrication process is simple, with high raw material utilization, significantly reducing production costs. High-voltage polarization distorts the perovskite lattice, promoting the ordered arrangement of ammonium methyl ions. The small molecular size and relatively low surface ligand density of short-chain ligands enhance film adhesion. Simultaneously, the low desorption energy of short-chain ligands facilitates rapid and uniform nucleation and spreading of perovskite quantum dots. High-quality 8-inch wafer-level thin film growth is achieved through the synergistic effects of external high-voltage electric field polarization, intermolecular interactions, and van der Waals forces between molecules and the substrate, making it highly promising for industrial production. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the preparation of wafer-level perovskite quantum dot thin films using the high-voltage electric field polarized perovskite quantum dot self-assembly deposition method of the present invention.

[0021] Figure 2 This is a photograph of the wafer-level perovskite quantum dot film prepared by the high-voltage electric field polarized perovskite quantum dot self-assembly deposition method in Embodiment 1 of the present invention.

[0022] Figure 3 These are XRD diffraction patterns of five regions selected from the wafer-level perovskite quantum dot thin film prepared by the high-voltage electric field polarized perovskite quantum dot self-assembly deposition method in Example 1 of this invention.

[0023] Figure 4 This is a SEM cross-sectional image of a wafer-level perovskite quantum dot film prepared by the high-voltage electric field polarized perovskite quantum dot self-assembly deposition method in Example 1 of the present invention.

[0024] Figure 5 These are AFM images of five different regions of a wafer-level perovskite quantum dot film prepared by the high-voltage electric field polarized perovskite quantum dot self-assembly deposition method according to Example 1 of this invention.

[0025] Figure 6 These are the peeling states of the film under different reverse peeling times in Embodiment 3 of the present invention, where a is the initial state, b is the film state after 5 minutes, c is the film state after 10 minutes, and d is the film state after 10 minutes. Detailed Implementation

[0026] 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.

[0027] This invention utilizes a high-voltage electric field-polarized perovskite quantum dot self-assembly deposition method to prepare wafer-level perovskite quantum dot thin films. First, perovskite quantum dot materials are synthesized at room temperature, purified, and then mixed with a mixed solution of toluene and acetonitrile to prepare an electrolyte. A substrate with a conductive film is inserted parallel to each other into an electrolytic cell. Then, a pair of positive and negative electrodes connected to an external power supply are connected to the substrate and added to the electrolyte. By controlling the power supply voltage and the energizing time, perovskite quantum dot thin film materials of different thicknesses can be obtained. This invention not only prepares wafer-level perovskite quantum dot thin film materials but also allows control of film thickness by adjusting the voltage and time of the high-voltage electric field-polarized perovskite quantum dot self-assembly deposition, and enables reverse peeling of the film by applying a reverse voltage.

[0028] This embodiment provides a method for preparing wafer-level perovskite quantum dot thin films by high-voltage electric field polarization self-assembly deposition, including the following steps: Step 1: The conductive substrate FTO is ultrasonically cleaned in an ultrasonic cleaner with acetone, ethanol and deionized water for 15 min in sequence, and then placed in an oven at 80 ℃ for 1 h for later use. Step 2: Perform ultraviolet ozone treatment on the dried conductive substrate FTO for 10 min; Step 3: The perovskite quantum dot material MAPbBr3 was synthesized at room temperature. The specific steps are as follows: Step S31: Add 0.8 mL of butylamine (BA) and 1.6 mL of propionic acid (PA) to 0.11 g (0.3 mmol) of PbBr2 and stir for about 5 minutes until dissolved to obtain a precursor solution with a BA:PA ligand volume ratio of 1:2, and obtain a PbBr2 precursor solution. Step S32: For the MA precursor, add 5 mL of PA to 0.24 g (2.6 mmol) of MAAc and stir for 5 minutes until dissolved to obtain the MA precursor solution; Step S33: Add 0.3 mL of PbBr2 precursor solution to 5 mL of toluene. Then quickly inject 0.45 mL of MA precursor solution (where PA:MA molar ratio is 1:6), and stir for 8 minutes to prepare PNCs; Step S34: Add 2 mL of n-hexane to the prepared crude PNC solution and centrifuge at 4000 r / min for 3 min to remove unreacted precursors; Step S35: The precipitate is redispersed in 2 mL of a mixed solvent of toluene and acetonitrile (volume ratio of toluene to acetonitrile is 8:2) for a second centrifugation purification. Step S36: The precipitate after the second centrifugation is redispersed in 32 mL of a mixed solvent of toluene and acetonitrile (volume ratio of toluene to acetonitrile is 8:2) to obtain 200 mL of MAPbBr3 quantum dot solution with a concentration of 2.5 mg / mL, which is used as the electrolyte. Step 4: The conductive substrates obtained in Step 2 are used as the negative and positive electrodes, respectively, and connected to an external DC power supply. The conductive surfaces of the substrates are then inserted into the electrolyte prepared in Step 3, with their conductive surfaces parallel to each other. The external power supply voltage is adjusted to 200 V, and a high-voltage electric field polarized perovskite quantum dot self-assembly deposition is performed for 3 minutes. After the deposition time is completed, the substrate of the positive electrode is removed, thus a MAPbBr3 quantum dot film is deposited on a substrate covered with fluorine-doped tin oxide (FTO). The film results of this embodiment are as follows: Figure 2 As shown, the photographs of wafer-level MAPbBr3 quantum dot films confirm the feasibility of wafer-level fabrication.

[0029] Example 2 This embodiment provides a method for preparing perovskite quantum dot thin films by high-voltage electric field polarization perovskite quantum dot self-assembly deposition, including the following steps: Step 1: The conductive substrate FTO is ultrasonically cleaned in an ultrasonic cleaner with acetone, ethanol and deionized water for 15 min in sequence, and then placed in an oven at 80 ℃ for 1 h for later use. Step 2: Perform ultraviolet ozone treatment on the dried conductive substrate FTO for 10 min; Step 3: The perovskite quantum dot material MAPbBr3 was synthesized at room temperature. The specific steps are as follows: Step S31: Add 0.8 mL BA and 1.6 mL PA to 0.11 g (0.3 mmol) of PbBr2 and stir for about 5 minutes until dissolved to obtain a precursor solution with a BA:PA ligand volume ratio of 1:2, and obtain a PbBr2 precursor solution. Step S32: For the MA precursor, add 5 mL of PA to 0.24 g (2.6 mmol) of MAAc and stir for 5 minutes until dissolved to obtain the MA precursor solution; Step S33: Add 0.3 mL of PbBr2 precursor solution to 5 mL of toluene. Then quickly inject 0.45 mL of MA precursor solution (wherein the Pb:MA molar ratio is 1:6), and stir for 8 minutes to prepare PNCs; Step S34: Add 2 mL of n-hexane to the prepared crude PNC solution and centrifuge at 4000 r / min for 3 min to remove unreacted precursors; Step S35: The precipitate was redispersed in 2 mL of a mixed solvent of toluene and acetonitrile (volume ratio = 8:2) for a second centrifugation purification; Step S36: The precipitate after the second centrifugation is redispersed in 16 mL of a mixed solvent of toluene and acetonitrile to obtain 200 mL of MAPbBr3 quantum dot solution with a concentration of 5 mg / mL, which is used as the electrolyte. Step 4: The conductive substrates from Step 2 were used as the negative and positive electrodes, respectively, and connected to an external DC power supply. The conductive surfaces of the substrates were then inserted into the electrolyte prepared in Step 3, with their conductive surfaces parallel to each other. The external power supply voltage was adjusted to 200 V, and the high-voltage electric field polarized perovskite quantum dot self-assembly deposition was performed. The deposition time was 15-65 s. After the deposition time was completed, the substrate of the positive electrode was removed, resulting in the deposition of a MAPbBr3 quantum dot film on a substrate covered with fluorine-doped tin oxide (FTO). The data are shown in Table 1. Table 1. Thickness of MAPbBr3 quantum dot films deposited by high-voltage electric field polarization perovskite quantum dots at different times. Example 3 This embodiment provides a method for high-voltage polarized field-controlled reverse exfoliation of perovskite quantum dot films, including the following steps: Step 1: The conductive substrate FTO is ultrasonically cleaned in an ultrasonic cleaner with acetone, ethanol and deionized water for 15 min in sequence, and then placed in an oven at 80 ℃ for 1 h for later use. Step 2: Perform ultraviolet ozone treatment on the dried conductive substrate FTO for 10 min; Step 3: Insert the perovskite quantum dot film deposited in Example 1 and the conductive FTO substrate treated in Step 2 into the electrolytic cell in parallel. Connect both to an external DC power supply. Connect the substrate with the film to the negative electrode and the blank substrate to the positive electrode. Adjust the external power supply voltage to 200 V. The reverse stripping time is 18-22 min. Figure 6 As shown, the MAPbBr3 quantum dot film was completely peeled off after the reverse deposition time ended.

[0030] Thin film characterization The wafer-level perovskite quantum dot thin film obtained in Example 1 was structurally characterized, and the results are as follows: Figures 3-5 As shown: like Figure 3 As shown, XRD tests were performed on five regions on the diagonal of the thin film, and the XRD patterns of the five regions of the thin film showed good uniformity.

[0031] like Figure 4 As shown, the SEM cross-sectional image of the thin film reveals its compactness.

[0032] like Figure 5 As shown, AFM testing was performed on five regions on the diagonal of the thin film, revealing the morphology of these five regions, which demonstrates the uniformity of the wafer-level perovskite quantum dot thin film.

[0033] The embodiments described above are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A method for preparing a wafer-level thin film of high-voltage electric field polarized perovskite quantum dots with reverse peeling capability, characterized in that, Includes the following steps: S1. Provide a conductive substrate; S2. Add the perovskite quantum dot material MAPbBr3 to a solvent and dissolve it to obtain an electrolyte; S3. Connect the conductive substrate to an external power source and place it in the electrolyte. Adjust the voltage of the external power source and control the high-voltage electric field to polarize the self-assembly deposition time of the perovskite quantum dots. This will deposit a perovskite quantum dot film on the conductive substrate, ultimately obtaining a wafer-level film.

2. The preparation method according to claim 1, characterized in that, The conductive substrate includes a rigid conductive substrate or a flexible conductive substrate.

3. The preparation method according to claim 2, characterized in that, The rigid conductive substrate is either FTO conductive glass or ITO conductive glass; the flexible conductive substrate is a PET conductive film.

4. The preparation method according to claim 1, characterized in that, The perovskite quantum dot material MAPbBr3 was prepared by the following method: A PbBr2 precursor solution and an MA precursor solution are provided; PbBr2 precursor solution was added to an organic solvent to obtain a mixture; MA precursor solution was added and stirred for 5-10 minutes to obtain PNCs; then an organic solvent was added and a first centrifugation was performed to remove unreacted precursors to obtain precipitate. The obtained precipitate was dispersed in a mixed solvent and purified by a second centrifugation to obtain the perovskite quantum dot material MAPbBr3.

5. The preparation method according to claim 4, characterized in that, The concentration of the PbBr2 precursor in the mixture was 0.28–0.3 mmol / ml; The organic solvent includes one or more of toluene, acetonitrile, butylamine, propionic acid, and n-hexane; The first centrifugation was performed at a speed of 3800~4000 r / min for 3~4 min.

6. The preparation method according to claim 5, characterized in that, The mixed solvent comprises toluene and acetonitrile, wherein the volume ratio of toluene to acetonitrile is (7:3) to (8:2).

7. The preparation method according to claim 1, characterized in that, The concentration of perovskite quantum dot material MAPbBr3 in the electrolyte is 2.5~3 mg / mL.

8. The preparation method according to claim 1, characterized in that, The external power supply is a DC power supply.

9. The preparation method according to claim 1, characterized in that, The voltage adjustment range of the external power supply is 0~200V.

10. The preparation method according to claim 1, characterized in that, The method for peeling off the self-assembled wafer-level thin film of high-voltage electric field polarized perovskite quantum dots that can be peeled off in reverse includes the following steps: Provides a conductive substrate and a well-deposited high-voltage electric field polarized perovskite quantum dot self-assembly deposition wafer-level thin film; Toluene and acetonitrile are mixed to obtain an electrolyte. The conductive substrate and the high-voltage electric field polarized perovskite quantum dot self-assembled deposition wafer-level thin film are placed in the electrolyte and connected to an external power source. By applying a reverse voltage of 190~200 V to the conductive substrate, adjusting the external voltage, and controlling the deposition time to 18~20 min, reverse peeling of the film can be achieved.

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