Two-dimensional / three-dimensional perovskite film and preparation method and application thereof

Abstract

This invention relates to perovskite thin films and provides a method for preparing two-dimensional / three-dimensional perovskite thin films, comprising the following steps: spin-coating a SnO2 solution onto a substrate and annealing; dissolving lead iodide, lead bromide, formamidinium iodide, and methylamine bromide in a mixed solution of DMSO and DMF, and adding cesium iodide dissolved in DMSO solution to the above solution; spin-coating onto a substrate and adding chlorobenzene; spin-coating magnetic nanoparticles of iron(III) oxide and a p-phenylenediamine iodide isopropanol solution onto the film under a magnetic field and annealing; dissolving Spiro-OMeTAD in a chlorobenzene solution, dissolving Li-TFSI in acetonitrile, and adding it along with TBP to the Spiro-OMeTAD solution and spin-coating onto the film surface; and depositing a metallic silver electrode. This invention provides a method for preparing two-dimensional / three-dimensional perovskite thin films. This invention also provides an application of two-dimensional / three-dimensional perovskite thin films in the fabrication of perovskite solar cells. This invention effectively improves the quality and stability of perovskite thin films.

Description

Technical Field

[0001] This invention relates to perovskite thin films, and more particularly to a two-dimensional / three-dimensional perovskite thin film, its preparation method, and its applications. Background Technology

[0002] Organic-inorganic hybrid perovskites have attracted widespread attention in the photovoltaic field due to their excellent properties such as high light absorption coefficient, high mobility, long carrier lifetime, and tunable bandgap. However, perovskite solar cells also face stability issues due to the instability of the perovskite absorber layer. Compared with three-dimensional perovskites, two-dimensional perovskites have better structural stability. Perovskite solar cells based on two-dimensional / three-dimensional heterostructures show great potential and are expected to improve both device performance and environmental stability.

[0003] Currently, the following methods are commonly used to prepare two-dimensional / three-dimensional heterostructure perovskite thin films: one method involves introducing two-dimensional perovskite into the interior of a three-dimensional perovskite thin film. Two-dimensional perovskite Embedded three-dimensional perovskite grain boundaries Location , this Effective grain boundary passivation can be achieved; however, during crystallization, large organic cations may disrupt the original three-dimensional perovskite microstructure, leading to disordered phase distribution in the film and hindering carrier transport. Another common method is to form a two-dimensional perovskite capping layer on the surface of the three-dimensional perovskite film, which has less impact on the three-dimensional perovskite crystallization process. However, the two-dimensional perovskite capping layer formed on the surface of the three-dimensional film lacks passivation effect on deep grain boundaries. Therefore, it is necessary to construct more suitable two-dimensional / three-dimensional heterostructures to achieve simultaneous passivation of grain boundaries and surface defects without interfering with the crystal growth process. However, such two-dimensional / three-dimensional heterostructures with two-dimensional perovskite uniformly embedded in the surface and grain boundaries of the three-dimensional perovskite film are difficult to construct using conventional spin-coating methods. Therefore, finding a suitable film preparation process requires further research. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing two-dimensional / three-dimensional perovskite thin films, aiming to solve the problems existing in the background art.

[0005] The present invention is implemented as follows: a method for preparing a two-dimensional / three-dimensional perovskite thin film includes the following steps:

[0006] Step 1: After cleaning and drying the ITO substrate, treat it with ultraviolet ozone.

[0007] Step 2: Spin-coat the SnO2 solution onto the substrate treated with ozone in Step 1, and place the substrate on a hot plate for annealing.

[0008] Step 3: Dissolve lead iodide, lead bromide, formamidinium iodide and methylamine bromide in a mixed solution of DMSO and DMF. Dissolve cesium iodide in DMSO solution and add it to the above solution to prepare a perovskite precursor solution.

[0009] Step 4: Spin-coat the perovskite precursor solution onto the substrate that has been annealed in Step 2, and drop chlorobenzene onto the surface of the formed film as an anti-solvent;

[0010] Step 5: Dissolve the magnetic nanoparticles of iron oxide and p-phenylenediamine iodine in an isopropanol solution. Under the action of a magnetic field, spin-coat the magnetic nanoparticles of iron oxide and the p-phenylenediamine iodine isopropanol solution onto the film from Step 4. Then place the film on a hot plate for annealing.

[0011] Step 6: Dissolve Spiro-OMeTAD in chlorobenzene solution and Li-TFSI in acetonitrile. Then add the Li-TFSI solution and TBP to the Spiro-OMeTAD solution.

[0012] Step 7: Spin-coat the final solution obtained in Step 6 onto the surface of the film after annealing in Step 5;

[0013] Step 8: Place the thin film obtained in step 7 into a vapor deposition apparatus and vapor deposit a metallic silver electrode.

[0014] Preferably, in step 1, the cleaning includes ultrasonic cleaning with deionized water, ethanol, acetone and ethanol in sequence.

[0015] Preferably, in step 1, the ultraviolet ozone treatment lasts for 15-20 minutes.

[0016] Preferably, in step 2, the annealing process is performed at 140-160°C for 20-30 minutes.

[0017] Preferably, in step 5, the annealing treatment is performed at 100-110°C for 50-60 minutes.

[0018] Another objective of this invention is to provide a method for preparing two-dimensional / three-dimensional perovskite thin films.

[0019] Another objective of this invention is to provide an application of two-dimensional / three-dimensional perovskite thin films in the fabrication of perovskite solar cells.

[0020] This invention provides a method for preparing a two-dimensional / three-dimensional perovskite thin film. Under the action of a magnetic field, the movement of magnetite nanoparticles along the grain boundaries promotes the downward movement of p-phenylenediamine cations along the grain boundaries, thereby realizing a novel two-dimensional / three-dimensional heterostructure. The two-dimensional perovskite covers the surface of the three-dimensional perovskite film and is embedded in the grain boundaries. This novel heterostructure can improve crystallinity, achieve simultaneous passivation of the film surface and grain boundaries, effectively promote vertical hole transport and provide a lateral barrier effect, and regulate the carrier transport process, enhancing the stability of the film, thereby improving the performance and stability of the device. Its photoelectric conversion efficiency can reach 24.21%. Attached Figure Description

[0021] Figure 1 Scanning electron microscope images of the thin films prepared in Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 1 provided for the present invention;

[0022] Figure 2 X-ray diffraction patterns of the thin films prepared in Comparative Examples 1, 2, 3 and 1 provided for this invention;

[0023] Figure 3 a represents the depth etching X-ray photoelectron spectroscopy of the thin films prepared in Comparative Example 1 and Example 1 provided by this invention; Figure 3 b shows the cross-sectional scanning electron microscope image and energy-dispersive X-ray spectrum of the thin film prepared in Example 1 of this invention;

[0024] Figure 4 The current-voltage curves and photoluminescence spectra of the thin films prepared in Comparative Examples 1, 2, 3, and 1 are provided for the present invention.

[0025] Figure 5 Time-resolved photoluminescence spectra of the thin films prepared in Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 1 provided for this invention;

[0026] Figure 6 The defect state density diagrams of the thin films prepared in Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 1 are provided for the present invention.

[0027] Figure 7 The current-voltage curves are for devices prepared from thin films based on Comparative Examples 1, 2, 3, and 1 provided by this invention.

[0028] Figure 8 X-ray diffraction patterns of the thin films prepared in Comparative Example 1 and Example 1 of this invention before and after 100 hours of storage;

[0029] Figure 9The graphs show the long-term stability and humidity stability of the devices prepared from the thin films obtained in Comparative Example 1 and Example 1 provided by the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] A two-dimensional / three-dimensional perovskite thin film, the preparation method of which includes the following steps:

[0032] Step 1: Clean the ITO substrate sequentially with deionized water, ethanol, acetone and ethanol using ultrasonic cleaning, dry it with nitrogen, and then treat the substrate with ultraviolet ozone for 15-20 minutes.

[0033] Step 2: Spin-coat the SnO2 solution onto the substrate from Step 1, and place the substrate on a hot plate for annealing at 140-160°C for 20-30 minutes;

[0034] Step 3: Dissolve 1.5 mM cesium iodide in 1 mL DMSO solution. Dissolve 1.1 mM lead iodide, 0.2 mM lead bromide, 1 mM formamidinium iodide and 0.2 mM methylamine bromide in 1 mL of a DMSO and DMF mixed solution with a volume ratio of 1:4. Then add 35-50 μL of cesium iodide solution to the above mixed solution to obtain the perovskite precursor solution.

[0035] Step 4: Take 75-100 μL of the perovskite precursor solution from Step 3 and spin-coat it onto the substrate from Step 2. Then, drop 140-160 μL of chlorobenzene onto the surface of the formed film as an anti-solvent.

[0036] Step 5: Dissolve the magnetic nanoparticles of iron oxide and p-phenylenediamine iodine in an isopropanol solution. Under the action of a magnetic field, spin-coat the isopropanol solution onto the film obtained in step 4. Then place the film on a hot plate and anneal at 100-110℃ for 50-60 min.

[0037] Step 6: Dissolve Spiro-OMeTAD in 1 mL of chlorobenzene solution and Li-TFSI in 1 mL of acetonitrile. Then add the Li-TFSI solution and TBP to the Spiro-OMeTAD solution.

[0038] Step 7: Spin-coat the solution obtained in Step 6 onto the surface of the film obtained in Step 5;

[0039] Step 8: Place the thin film obtained in step 7 into a vapor deposition apparatus to vapor deposit a metallic silver electrode.

[0040] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0041] Example 1: A two-dimensional / three-dimensional perovskite thin film, the preparation method of which includes the following steps:

[0042] Step 1: Clean the ITO substrate sequentially with deionized water, ethanol, acetone and ethanol using ultrasonic cleaning, dry it with nitrogen, and then treat the substrate with ultraviolet ozone for 20 minutes.

[0043] Step 2: Spin-coat the SnO2 solution onto the substrate from Step 1, and place the substrate on a hot plate for annealing at 150°C for 30 minutes;

[0044] Step 3: Dissolve 1.5 mM cesium iodide in 1 mL DMSO solution. Dissolve 1.1 mM lead iodide, 0.2 mM lead bromide, 1 mM formamidinium iodide and 0.2 mM methylamine bromide in 1 mL of a DMSO and DMF mixture with a volume ratio of 1:4. Then add 40 μL of cesium iodide solution to the above mixture to obtain the perovskite precursor solution.

[0045] Step 4: Take 90 μL of the perovskite precursor solution from Step 3 and spin-coat it onto the substrate from Step 2. Then, drop 150 μL of chlorobenzene onto the surface of the formed film as an anti-solvent.

[0046] Step 5: Dissolve the magnetic nanoparticles of iron oxide and p-phenylenediamine iodine in an isopropanol solution. Under the action of a magnetic field, spin-coat the isopropanol solution onto the film obtained in step 4. Then place the film on a hot plate and anneal at 100°C for 60 min.

[0047] Step 6: Dissolve Spiro-OMeTAD in 1 mL of chlorobenzene solution and Li-TFSI in 1 mL of acetonitrile. Then add the Li-TFSI solution and TBP to the Spiro-OMeTAD solution.

[0048] Step 7: Spin-coat the solution obtained in Step 6 onto the surface of the film obtained in Step 5;

[0049] Step 8: Place the thin film obtained in step 7 into a vapor deposition apparatus to vapor deposit a metallic silver electrode.

[0050] Example 2: A two-dimensional / three-dimensional perovskite thin film, the preparation method of which includes the following steps:

[0051] Step 1: Clean the ITO substrate sequentially with deionized water, ethanol, acetone and ethanol using ultrasonic cleaning, dry it with nitrogen, and then treat the substrate with ultraviolet ozone for 15 minutes.

[0052] Step 2: Spin-coat the SnO2 solution onto the substrate from Step 1, and place the substrate on a hot plate for annealing at 140°C for 30 minutes;

[0053] Step 3: Dissolve 1.5 mM cesium iodide in 1 mL of DMSO solution. Dissolve 1.1 mM lead iodide, 0.2 mM lead bromide, 1 mM formamidinium iodide and 0.2 mM methylamine bromide in 1 mL of a DMSO and DMF mixed solution with a volume ratio of 1:4. Then add 35 μL of cesium iodide solution to the above mixed solution to obtain the perovskite precursor solution.

[0054] Step 4: Take 75 μL of the perovskite precursor solution from Step 3 and spin-coat it onto the substrate from Step 2. Then, drop 140 μL of chlorobenzene onto the surface of the formed film as an antisolvent.

[0055] Step 5: Dissolve the magnetic nanoparticles of iron oxide and p-phenylenediamine iodine in an isopropanol solution. Under the action of a magnetic field, spin-coat the isopropanol solution onto the film obtained in step 4. Then place the film on a hot plate and anneal at 100°C for 60 min.

[0056] Step 6: Dissolve Spiro-OMeTAD in 1 mL of chlorobenzene solution and Li-TFSI in 1 mL of acetonitrile. Then add the Li-TFSI solution and TBP to the Spiro-OMeTAD solution.

[0057] Step 7: Spin-coat the solution obtained in Step 6 onto the surface of the film obtained in Step 5;

[0058] Step 8: Place the thin film obtained in step 7 into a vapor deposition apparatus to vapor deposit a metallic silver electrode.

[0059] Example 3: A two-dimensional / three-dimensional perovskite thin film, the preparation method of which includes the following steps:

[0060] Step 1: The ITO substrate was ultrasonically cleaned sequentially with deionized water, ethanol, acetone and ethanol, dried with nitrogen, and then treated with ultraviolet ozone for 18 minutes.

[0061] Step 2: Spin-coat the SnO2 solution onto the substrate from Step 1, and place the substrate on a hot plate for annealing at 160°C for 20 minutes;

[0062] Step 3: Dissolve 1.5 mM cesium iodide in 1 mL of DMSO solution. Dissolve 1.1 mM lead iodide, 0.2 mM lead bromide, 1 mM formamidinium iodide and 0.2 mM methylamine bromide in 1 mL of a DMSO and DMF mixed solution with a volume ratio of 1:4. Then add 50 μL of cesium iodide solution to the above mixed solution to obtain the perovskite precursor solution.

[0063] Step 4: Take 100 μL of the perovskite precursor solution from Step 3 and spin-coat it onto the substrate from Step 2. Then, drop 160 μL of chlorobenzene onto the surface of the formed film as an antisolvent.

[0064] Step 5: Dissolve the magnetic nanoparticles of iron oxide and p-phenylenediamine iodine in an isopropanol solution. Under the action of a magnetic field, spin-coat the isopropanol solution onto the film obtained in step 4. Then place the film on a hot plate and anneal at 110°C for 50 min.

[0065] Step 6: Dissolve Spiro-OMeTAD in 1 mL of chlorobenzene solution and Li-TFSI in 1 mL of acetonitrile. Then add the Li-TFSI solution and TBP to the Spiro-OMeTAD solution.

[0066] Step 7: Spin-coat the solution obtained in Step 6 onto the surface of the film obtained in Step 5;

[0067] Step 8: Place the thin film obtained in step 7 into a vapor deposition apparatus to vapor deposit a metallic silver electrode.

[0068] Comparative Example 1: A three-dimensional perovskite thin film, the preparation method of which includes the following steps:

[0069] Step 1: Clean the ITO substrate sequentially with deionized water, ethanol, acetone and ethanol using ultrasonic cleaning, dry it with nitrogen, and then treat the substrate with ultraviolet ozone for 20 minutes.

[0070] Step 2: Spin-coat the SnO2 solution onto the substrate from Step 1, and place the substrate on a hot plate for annealing at 150°C for 30 minutes;

[0071] Step 3: Dissolve 1.5 mM cesium iodide in 1 mL DMSO solution. Dissolve 1.1 mM lead iodide, 0.2 mM lead bromide, 1 mM formamidinium iodide and 0.2 mM methylamine bromide in 1 mL of a DMSO and DMF mixture with a volume ratio of 1:4. Then add 40 μL of cesium iodide solution to the above mixture to obtain the perovskite precursor solution.

[0072] Step 4: Take 90 μL of the perovskite precursor solution from Step 3 and spin-coat it onto the substrate from Step 2. Then, drop 150 μL of chlorobenzene onto the surface of the formed film as an anti-solvent.

[0073] Step 5: Place the film on a hot plate and anneal at 100°C for 60 minutes;

[0074] Step 6: Dissolve Spiro-OMeTAD in 1 mL of chlorobenzene solution and Li-TFSI in 1 mL of acetonitrile. Then add the Li-TFSI solution and TBP to the Spiro-OMeTAD solution.

[0075] Step 7: Spin-coat the solution obtained in Step 6 onto the surface of the film obtained in Step 5;

[0076] Step 8: Place the thin film obtained in step 7 into a vapor deposition apparatus to vapor deposit a metallic silver electrode.

[0077] Comparative Example 2: A two-dimensional / three-dimensional perovskite thin film, the preparation method of which includes the following steps:

[0078] Step 1: Clean the ITO substrate sequentially with deionized water, ethanol, acetone and ethanol using ultrasonic cleaning, dry it with nitrogen, and then treat the substrate with ultraviolet ozone for 20 minutes.

[0079] Step 2: Spin-coat the SnO2 solution onto the substrate from Step 1, and place the substrate on a hot plate for annealing at 150°C for 30 minutes;

[0080] Step 3: Dissolve 1.5 mM cesium iodide in 1 mL DMSO solution. Dissolve 1.1 mM lead iodide, 0.2 mM lead bromide, 1 mM formamidinium iodide and 0.2 mM methylamine bromide in 1 mL of a DMSO and DMF mixture with a volume ratio of 1:4. Then add 40 μL of cesium iodide solution to the above mixture to obtain the perovskite precursor solution.

[0081] Step 4: Take 90 μL of the perovskite precursor solution from Step 3 and spin-coat it onto the substrate from Step 2. Then, drop 150 μL of chlorobenzene onto the surface of the formed film as an anti-solvent.

[0082] Step 5: Dissolve p-phenylenediamine iodine in isopropanol solution, then spin-coat the isopropanol solution onto the film obtained in step 4, and then place the film on a hot plate and anneal at 100°C for 60 min.

[0083] Step 6: Dissolve Spiro-OMeTAD in 1 mL of chlorobenzene solution and Li-TFSI in 1 mL of acetonitrile. Then add the Li-TFSI solution and TBP to the Spiro-OMeTAD solution.

[0084] Step 7: Spin-coat the solution obtained in Step 6 onto the surface of the film obtained in Step 5;

[0085] Step 8: Place the thin film obtained in step 7 into a vapor deposition apparatus to vapor deposit a metallic silver electrode.

[0086] Comparative Example 3: A two-dimensional / three-dimensional perovskite thin film, the preparation method of which includes the following steps:

[0087] Step 1: Clean the ITO substrate sequentially with deionized water, ethanol, acetone and ethanol using ultrasonic cleaning, dry it with nitrogen, and then treat the substrate with ultraviolet ozone for 20 minutes.

[0088] Step 2: Spin-coat the SnO2 solution onto the substrate from Step 1, and place the substrate on a hot plate for annealing at 150°C for 30 minutes;

[0089] Step 3: Dissolve 1.5 mM cesium iodide in 1 mL DMSO solution. Dissolve 1.1 mM lead iodide, 0.2 mM lead bromide, 1 mM formamidinium iodide and 0.2 mM methylamine bromide in 1 mL of a DMSO and DMF mixture with a volume ratio of 1:4. Then add 40 μL of cesium iodide solution to the above mixture to obtain the perovskite precursor solution.

[0090] Step 4: Take 90 μL of the perovskite precursor solution from Step 3 and spin-coat it onto the substrate from Step 2. Then, drop 150 μL of chlorobenzene onto the surface of the formed film as an anti-solvent.

[0091] Step 5: Dissolve the magnetite nanoparticles and p-phenylenediamine iodine in an isopropanol solution, then spin-coat the isopropanol solution onto the film obtained in step 4, and then place the film on a hot plate and anneal at 100°C for 60 min.

[0092] Step 6: Dissolve Spiro-OMeTAD in 1 mL of chlorobenzene solution and Li-TFSI in 1 mL of acetonitrile. Then add the Li-TFSI solution and TBP to the Spiro-OMeTAD solution.

[0093] Step 7: Spin-coat the solution obtained in Step 6 onto the surface of the film obtained in Step 5;

[0094] Step 8: Place the thin film obtained in step 7 into a vapor deposition apparatus to vapor deposit a metallic silver electrode.

[0095] Performance testing:

[0096] The films prepared in Comparative Examples 1, 2, 3, and 1 were analyzed and their performance was tested. The results are as follows:

[0097] like Figure 1 As shown, Figure 1 The images shown are scanning electron microscope images of a three-dimensional perovskite film, a perovskite film modified with p-phenylenediamine iodine, a perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine, and a perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine under a magnetic field.

[0098] like Figure 2The images show the X-ray diffraction patterns of a three-dimensional perovskite film, a perovskite film modified with p-phenylenediamine iodine, a perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine, and a perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine under a magnetic field.

[0099] like Figure 3 As shown, Figure 3 a represents the X-ray photoelectron spectra of a three-dimensional perovskite film and a perovskite film co-modified with magnetite nanoparticles and p-phenylenediamine iodine under a magnetic field, as well as the X-ray photoelectron spectra of a perovskite film co-modified with magnetite nanoparticles and p-phenylenediamine iodine under a magnetic field. Figure 3 b shows the cross-sectional scanning electron microscope image and energy-dispersive X-ray spectrum of the perovskite film co-modified with iron oxide magnetic nanoparticles and p-phenylenediamine iodine under the action of a magnetic field.

[0100] like Figure 4 As shown, Figure 4 a and b represent the current-voltage curves and photoluminescence spectra of the three-dimensional perovskite film, the perovskite film modified with p-phenylenediamine iodine, the perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine, and the perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine under the action of a magnetic field.

[0101] like Figure 5 The image shows the time-resolved photoluminescence spectra of a three-dimensional perovskite film, a perovskite film modified with p-phenylenediamine iodine, a perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine, and a perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine under a magnetic field.

[0102] like Figure 6 The diagram shows the defect density of states of a three-dimensional perovskite film, a perovskite film modified with p-phenylenediamine iodine, a perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine, and a perovskite film modified with magnetite nanoparticles and p-phenylenediamine iodine under the action of a magnetic field.

[0103] like Figure 7 As shown, the current-voltage curves of devices based on three-dimensional perovskite films, perovskite films modified with p-phenylenediamine iodine, perovskite films modified with both magnetite nanoparticles and p-phenylenediamine iodine, and perovskite films modified with both magnetite nanoparticles and p-phenylenediamine iodine under magnetic field are displayed.

[0104] like Figure 8The image shows the X-ray diffraction patterns of a three-dimensional perovskite film and a perovskite film co-modified with magnetite nanoparticles and p-phenylenediamine iodine under a magnetic field before and after 100 hours of exposure.

[0105] like Figure 9 The figure shows the long-term stability and humidity stability of the three-dimensional perovskite device and the device co-modified with magnetite nanoparticles and p-phenylenediamine iodine under the action of a magnetic field.

[0106] In summary, compared to the other three types of perovskite films, the perovskite film spin-coated with magnetite nanoparticles and p-phenylenediamine iodide isopropanol solution exhibits a larger grain size and a smoother surface under an applied magnetic field (e.g., ...). Figure 1 As shown); under the action of an external magnetic field, two-dimensional perovskite (as shown) forms on the surface and at the grain boundaries of a three-dimensional perovskite film spin-coated with magnetite nanoparticles and p-phenylenediamine iodide isopropanol solution. Figure 2 and Figure 3 As shown), this novel heterostructure can provide a lateral barrier effect and effectively promote vertical hole transport (e.g., Figure 4 As shown), this novel heterostructure also effectively suppresses nonradiative recombination in perovskite films and achieves effective passivation of film defects (e.g. Figure 5 and Figure 6 (As shown); Applying the thin film provided in the embodiments of the present invention to the fabrication of devices can achieve a high photoelectric conversion efficiency of 24.21% (e.g. Figure 7 As shown), the film also exhibits enhanced humidity stability. Figure 8 As shown), the long-term stability and humidity stability of the device have also been significantly improved (e.g. Figure 9 (As shown).

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a two-dimensional / three-dimensional perovskite thin film, characterized in that, Includes the following steps: Step 1: After cleaning and drying the ITO substrate, treat it with ultraviolet ozone. Step 2: Spin-coat the SnO2 solution onto the substrate treated with ozone in Step 1, and place the substrate on a hot plate for annealing. Step 3: Dissolve lead iodide, lead bromide, formamidinium iodide and methylamine bromide in a mixed solution of DMSO and DMF. Dissolve cesium iodide in DMSO solution and add it to the above solution to prepare a perovskite precursor solution. Step 4: Spin-coat the perovskite precursor solution onto the substrate that has been annealed in Step 2, and drop chlorobenzene onto the surface of the formed film as an anti-solvent; Step 5: Dissolve the magnetic nanoparticles of iron oxide and p-phenylenediamine iodine in an isopropanol solution. Under the action of a magnetic field, spin-coat the magnetic nanoparticles of iron oxide and the p-phenylenediamine iodine isopropanol solution onto the film from Step 4. Then place the film on a hot plate for annealing. Step 6: Dissolve Spiro-OMeTAD in chlorobenzene solution and Li-TFSI in acetonitrile. Then add the Li-TFSI solution and TBP to the Spiro-OMeTAD solution. Step 7: Spin-coat the final solution obtained in Step 6 onto the surface of the film after annealing in Step 5; Step 8: Place the thin film obtained in step 7 into a vapor deposition apparatus and vapor deposit a metallic silver electrode.

2. The method for preparing two-dimensional / three-dimensional perovskite thin films according to claim 1, characterized in that, In step 1, the cleaning process includes ultrasonic cleaning with deionized water, ethanol, acetone and ethanol in sequence.

3. The method for preparing two-dimensional / three-dimensional perovskite thin films according to claim 1, characterized in that, In step 1, the ultraviolet ozone treatment lasts for 15-20 minutes.

4. The method for preparing two-dimensional / three-dimensional perovskite thin films according to claim 1, characterized in that, In step 2, the annealing process is performed at 140-160℃ for 20-30 minutes.

5. The method for preparing two-dimensional / three-dimensional perovskite thin films according to claim 1, characterized in that, In step 5, the annealing process is performed at 100-110°C for 50-60 minutes.

6. A two-dimensional / three-dimensional perovskite thin film prepared by a method according to any one of claims 1-5.

7. The application of a two-dimensional / three-dimensional perovskite thin film as described in claim 6 in the fabrication of perovskite solar cells.

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