Preparation method of shape-preserving perovskite thin film and application thereof

Abstract

The application discloses a preparation method of a shape-preserving perovskite film and application thereof, and belongs to the technical field of perovskite photoelectric materials. i ) m B n X m+2n , and then a solution with a solute of A j X is spin-coated to form a film. The preparation method is mild in conditions, does not require high temperature, vacuum and other environments, is simple in preparation process, low in cost and easy to mass production, can deposit a high-quality shape-preserving perovskite film on a substrate with large surface undulation such as a textured silicon, completely covers the entire textured structure, and is convenient for carrier transmission.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of perovskite photoelectric materials, and particularly relates to a preparation method of a shape-retaining perovskite film and application thereof. BACKGROUND

[0002] Energy problems are increasingly serious in today's era, and photovoltaic technology is increasingly favored by people. The most widely used solar cell at present is a crystalline silicon solar cell, which has the characteristics of relatively low manufacturing cost, mature technology route and easy large-area production, however, its photoelectric conversion efficiency has approached its theoretical limit. Compared with crystalline silicon solar cells, perovskite solar cells have lower manufacturing cost, excellent performance and simple process, and in particular, their photoelectric conversion efficiency has broken through 25%, and they are increasingly attracting people's attention. The light-absorbing layer of the perovskite solar cell is an organic-inorganic halide perovskite material, which has a composition of ABX3, including A-site cations, B-site cations and X anions.

[0003] Although perovskite materials develop rapidly, the highest conversion efficiency of single-junction perovskite solar cells is 25.8%, but it will ultimately be limited by the Shockley-Queisser limit, and the space for improving conversion efficiency will gradually shrink in the process of approaching this limit. In order to further improve the photoelectric conversion efficiency of solar cells, crystalline silicon / perovskite tandem solar cells have become a very feasible solution. Perovskite solar cells have high absorption in the visible light spectrum, while crystalline silicon solar cells have a wide absorption spectrum (300-1200 nm), and the two can complement each other to achieve full utilization of solar energy. For example, the Chinese patent document with publication number CN115621331A discloses a perovskite tandem solar cell, which includes a silicon bottom cell and a perovskite top cell, the top surface of the silicon bottom cell is sequentially provided with a silicon oxide layer and a P-type doped amorphous silicon layer, and the P-type doped amorphous silicon layer is located at the bottom surface of the perovskite top cell; the perovskite top cell contains alkali metal ions in the perovskite light-absorbing layer; the P-type doped amorphous silicon layer is a disordered silicon element with many defects, which facilitates the movement of charge carriers, and the cooperation of the silicon oxide layer and the P-type doped amorphous silicon layer can increase the tunneling of charge carriers.

[0004] However, the surface of the silicon wafer used to manufacture crystalline silicon cells has a large relief after texturing, so the conformal growth of perovskite films on the top surface of the silicon wafer is a difficult problem to be solved, otherwise the perovskite film prepared leaves many pores and gaps between the silicon wafer, which greatly affects the carrier transport. To solve this problem, two solutions have appeared in the field. One is to grow a perovskite film with good conformality on the silicon wafer by vacuum evaporation process, but this method lacks the intermediate phase reaction process in the solution method, resulting in unsatisfactory quality, and the process requires multiple evaporation sources, which is complex and limits its further commercial application. The other is to use the solution method to grow a perovskite film with a thickness greater than the size of the silicon wafer surface pyramid, but increasing the thickness of the perovskite will increase the resistance of the cell device and affect the photoelectric performance of the crystalline silicon / perovskite tandem solar cell.

[0005] Chinese patent document CN114335359A discloses a method for making a perovskite film. The process of the method comprises: providing a substrate, the surface of the substrate having a textured structure; forming a metal halide skeleton layer on the substrate with a textured structure, the metal halide skeleton layer conformally covering the textured structure; forming a perovskite light absorption layer in the shape of the textured structure on the metal halide skeleton layer with a textured structure; wherein the metal halide skeleton layer plays an anchoring role, so that the subsequently formed perovskite light absorption layer can form a perovskite film with the relief of the textured structure. However, in this method, an additional metal halide skeleton layer needs to be introduced, and the steps are more complicated. SUMMARY

[0006] The present application provides a method for preparing a conformal perovskite film. The whole process uses a solution method to form a film, the conditions are mild, and high-quality conformal perovskite films can be deposited on substrates with large surface relief such as textured silicon without high temperature, vacuum, etc. The entire textured structure is completely covered.

[0007] Specifically, the following two technical solutions are adopted:

[0008] Method 1: A method for preparing a conformal perovskite film, comprising the following steps:

[0009] S01, providing a substrate, the surface of the substrate having a textured structure;

[0010] S02, preparing a perovskite precursor solution by mixing solute AX and BX2 with a first solvent, immersing the substrate in the perovskite precursor solution, placing a first container containing the substrate and the perovskite precursor solution in a second container containing an anti-solvent, and diffusing the anti-solvent vapor in the second container to the first container, and standing to promote the crystallization and deposition of ABX3 perovskite on the substrate;

[0011] S03, the substrate is taken out from spin coating, the anti-solvent is added dropwise, and then annealing treatment is performed to obtain a conformal perovskite film.

[0012] wherein AX is selected from at least one of FAI, FABr, FACl, MAI, MACl, MABr, CsI, CsCl, and CsBr; and BX2 is selected from at least one of PbI2, PbCl2, PbBr2, SnI2, SnCl2, and SnBr2.

[0013] The method of the present application uses a solution method to form a film, and in the process of depositing perovskite in an anti-solvent atmosphere, as the anti-solvent gradually penetrates into the precursor solution, the saturation of the solution increases, which promotes the rapid formation of a large number of crystal nuclei. The crystal nuclei in the solution can be uniformly attached to the textured substrate, and further in the subsequent spin coating process, as the solvent evaporates, the crystals grow to form a perovskite film with a thickness of 500-800 nm.

[0014] Preferably, the substrate is a textured silicon substrate.

[0015] In step S02, the first solvent is at least one of dimethylformamide, dimethyl sulfoxide, gamma-butyrolactone, 2-methoxyethanol, acetonitrile, tetramethyl sulfoxide, propylene carbonate, dimethylacetamide, dimethylaceto urea, and N-methyl-2-pyrrolidone.

[0016] In step S02, the anti-solvent is at least one of dichloromethane, diethyl ether, chlorobenzene, ethyl acetate, anisole, n-hexane, and toluene.

[0017] Preferably, in step S02, the total concentration of the perovskite precursor solution is 1-5 mol / L; and the molar ratio of AX to BX2 is 1:1.

[0018] Preferably, in step S02, the diffusion time of the anti-solvent vapor in the second container to the first container is 10 min-2 h.

[0019] Preferably, in step S03, spin coating is performed on a spin coater, and the spin coating speed is slow at first and then fast. Specifically, the process parameters of step S03 are as follows: 500-1500 rpm spin coating for 5-15 s, adding 200-800 μL of anti-solvent dropwise, continuing to spin at 3000-6000 rpm for 30-90 s, and annealing treatment at 110-150 °C for 10-30 min.

[0020] Method 2: A method for preparing a conformal perovskite film, comprising the following steps:

[0021] S11, providing a substrate, wherein the surface of the substrate has a textured structure;

[0022] S12, dissolving a solute Ai X, BX2 and a first solvent are formulated into a first precursor solution, the substrate is immersed in the first precursor solution, a first container containing the substrate and the first precursor solution is placed in a second container containing an anti-solvent, anti-solvent vapor in the second container diffuses to the first container, and standing promotes (A i ) m B n X m+2n crystalline deposition on the substrate; (A i ) m B n X m+2n wherein 0 < m < 1 and 0 < n < 1;

[0023] S13, the solute A j X and a second solvent are formulated into a second precursor solution, the substrate is taken out and spin-coated, the second precursor solution is added dropwise, spin-coating is continued, and then annealing treatment is performed to obtain a conformal perovskite film;

[0024] wherein A i X is selected from at least one of CsI, CsCl and CsBr; BX2 is selected from at least one of PbI2, PbCl2, PbBr2, SnI2, SnCl2 and SnBr2; A j X is selected from at least one of FAI, FABr, FACl, MAI, MACl and MABr.

[0025] The method uses a solution method for film formation throughout the whole process flow. In the process of depositing perovskite partial components in an anti-solvent atmosphere, as the anti-solvent gradually penetrates into the precursor solution, the saturation of the solution increases, which promotes the rapid formation of a large number of crystal nuclei. The crystal nuclei in the solution can be uniformly attached to the textured substrate, and further, in the subsequent spin-coating process, as the solvent volatilizes, the crystals grow to form a 500-800 nm thick perovskite film.

[0026] Preferably, the substrate is a textured silicon substrate.

[0027] In step S12, the first solvent is at least one of dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, 2-methoxyethanol, acetonitrile, tetramethyl sulfoxide, propylene carbonate, dimethylacetamide, dimethylaceto urea, and N-methyl-2-pyrrolidone.

[0028] In step S12, the anti-solvent is at least one of dichloromethane, diethyl ether, chlorobenzene, ethyl acetate, anisole, n-hexane, and toluene.

[0029] In step S12, the concentration of the first precursor solution is 1.4-2 mol / L.

[0030] Preferably, in step S12, the time for the anti-solvent vapor in the second container to diffuse to the first container is 10 min to 2 h.

[0031] In step S13, the second solvent is isopropanol and / or trifluoroethanol, and the concentration of the second precursor solution is 0.7-1 mol / L.

[0032] In step S13, the spin coating is performed on a spin coater, and the process parameters of step S13 are as follows: the substrate is taken out and spin coated at 1000-3000 rpm for 10-60 s, 30-100 μL of the second precursor solution is added dropwise, and spin coating is continued at 1000-3000 rpm for 30-60 s; and the process parameters of the annealing treatment are as follows: annealing at 110-150 ℃ for 10-30 min.

[0033] The application also provides the application of the conformal perovskite thin film prepared by the method to the field of batteries, in particular, to the field of stacked batteries.

[0034] Compared with the prior art, the application has the following beneficial effects:

[0035] (1) The method for preparing the conformal perovskite thin film provided by the application uses a solution method in the whole process, does not require high temperature and vacuum environment, is easy to dope, has simple preparation process, low cost, can realize large-area deposition, and is easy to mass produce.

[0036] (2) The method for preparing the conformal perovskite thin film provided by the application can deposit a high-quality conformal perovskite thin film on a substrate with large surface undulation such as textured silicon, the surface undulation of the textured silicon can reach several microns, the entire textured structure is completely covered, and carrier transmission is facilitated. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The SEM image of the conformal perovskite thin film prepared in Example 1.

[0038] Figure 2 The xrd image of the conformal perovskite thin film prepared in Example 1.

[0039] Figure 3 The cross-sectional SEM image of the conformal perovskite thin film prepared in Example 1.

[0040] Figure 4 The SEM image of the textured silicon substrate corresponding to Example 1.

[0041] Figure 5 The SEM image of the perovskite thin film prepared in Comparative Example 1.

[0042] Figure 6 The SEM image of the conformal perovskite thin film prepared in Example 3.

[0043] Figure 7 XRD pattern of the conformal perovskite thin film prepared in Example 3.

[0044] Figure 8 Cross-sectional SEM image of the conformal perovskite thin film prepared in Example 3.

[0045] Figure 9 SEM image of the perovskite thin film prepared in Comparative Example 2. DETAILED DESCRIPTION

[0046] The application will be further clarified by the following examples which are intended to be exemplary of the application. It should be understood that these examples are in no way to be considered as limiting the scope of the application. Methods of operation which are not specifically noted in the examples below are generally performed according to conventional methods or as suggested by the manufacturer.

[0047] Example 1

[0048] A perovskite thin film was prepared on a textured silicon substrate using Method 2, with dichloromethane (DCM) as the anti-solvent, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) as the first solvent, and isopropyl alcohol (IPA) as the second solvent.

[0049] (1) A textured silicon substrate was provided;

[0050] (2) At room temperature, CsBr, PbBr2and PbI2were dissolved in the first solvent (volume ratio of DMF and DMSO was 193:7) and stirred until fully dissolved to prepare a first precursor solution with a total concentration of 1.4 M; the substrate was immersed in the first precursor solution (the surface of the substrate to be deposited did not contact the inner wall of the first container); the first container containing the substrate and the first precursor solution was then placed in a second container containing the anti-solvent dichloromethane, and the anti-solvent vapor in the second container diffused into the first container, and the substrate was left to deposit for 15 min, promoting the crystallization of Cs 0.05 PbI 1.6 Br 0.45 on the substrate;

[0051] (3) The solutes FAI and MABr were dissolved in isopropyl alcohol and stirred until fully dissolved to obtain a second precursor solution with a concentration of 0.7 M; the substrate was removed and placed on a spin coater, and rotated at a speed of 1500 rpm for 30 s, then 50 μL of the second precursor solution was added dropwise, and the substrate was rotated at a speed of 1800 rpm for 40 s; after spin coating, the substrate was placed on a hot stage at 90 °C for 1 min, and then annealed at 150 °C for 10 min under 30-40% RH, to obtain a conformal FA 0.74 MA 0.21 Cs 0.05 PbI 2.34 Br0.66 perovskite thin film.

[0052] Comparative Example 1

[0053] The method of step (1) and step (2) in Comparative Example 1 is the same as that in Example 1, the only difference is that in step (3):

[0054] The substrate is taken out and placed on a spin coater, first rotating at 1000 rpm for 3 s, then rotating at 4000 rpm for 60 s, and 300 microliters of ethyl acetate anti-solvent is dropped into the 10th second of the start of spin coating; after spin coating, the substrate is placed on a hot stage at 70°C for 1 min, and then annealed at 130°C for 30 min.

[0055] Example 2

[0056] In this example, the preparation method of the conformal perovskite thin film is different from that of Example 1 only in that the total concentration of the first precursor solution is 2M, the total concentration of the second precursor solution is 1M, the second solvent is trifluoroethanol, and the deposition is 20 min.

[0057] Example 3

[0058] Method 1 is used to prepare perovskite thin film on a suede silicon substrate, using dichloromethane (DCM) and ethyl acetate as anti-solvents, respectively, and dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) as the first solvent, with a ratio of 4:1.

[0059] (1) Provide a suede silicon substrate;

[0060] (2) At room temperature, CsI, PbBr2, PbI2, FAI, and MABr are dissolved in the first solvent, stirred uniformly and fully dissolved to prepare a perovskite precursor solution with a total concentration of 2M (the molar ratio of AX and BX2 is 1:1), and the substrate is immersed in the perovskite precursor solution (the deposition surface of the substrate does not contact the inner wall of the first container); then the first container containing the substrate and the perovskite precursor solution is placed in the second container containing the anti-solvent dichloromethane, and the anti-solvent vapor in the second container diffuses to the first container, and the deposition is 20 min, which promotes the crystallization of Cs 0.05 FA 0.6 MA 0.35 PbI 1.65 Br 1.35 perovskite crystallizes and deposits on the substrate;

[0061] (3) Remove the substrate and place it on a spin coater. First, spin coat at 1000 rpm for 5 seconds, then at 4000 rpm for 60 seconds. At the 10th second after the start of spin coating, drop in 300 μL of the anti-solvent ethyl acetate. After spin coating, place the substrate on a 70°C hot plate for 1 minute, then on a 150°C hot plate for annealing for 10 minutes to obtain the conformal Cs. 0.05 FA 0.6 MA 0.35 PbI 1.65 Br 1.35 Perovskite thin films.

[0062] Comparative Example 2

[0063] The only difference between the preparation method of the perovskite film in Comparative Example 2 and that in Example 3 is that, in step (3), the antisolvent ethyl acetate is not added.

[0064] Example 4

[0065] In this embodiment, the difference between the preparation method of the conformal perovskite film and that in Example 3 is that the total concentration of the perovskite precursor solution is 2.5M and the deposition is allowed to stand for 25 minutes.

[0066] Sample Analysis

[0067] The morphology of the conformal perovskite thin film prepared in Example 1 under a scanning electron microscope is as follows: Figure 1 As shown, the cross-sectional morphology is as follows Figure 3 As shown, the X-ray diffraction pattern is as follows: Figure 2 As shown, the morphology of the textured silicon substrate used is as follows: Figure 4 As shown, the conformal perovskite film exhibits excellent conformal properties with the textured silicon substrate pyramid, with no exposed pyramid tips on the textured silicon substrate, indicating that the method of this invention successfully deposited a conformal perovskite film. The SEM image of the perovskite film in Comparative Example 1 is shown below. Figure 5 As shown, the pyramidal tips of the textured silicon substrate are clearly exposed, indicating that the method of the present invention has a better effect on depositing perovskite thin films.

[0068] The morphology of the conformal perovskite thin film prepared in Example 3 under a scanning electron microscope is as follows: Figure 6 As shown, the cross-sectional morphology is as follows Figure 8 As shown, the X-ray diffraction pattern is as follows: Figure 7 As shown, the textured silicon substrate used is the same as that in Example 1, and the morphology of the perovskite film in Comparative Example 2 is as follows. Figure 9 As shown. Compared with Comparative Example 2, the perovskite film in Example 3 exhibits excellent conformability with no pyramid tip exposure, indicating that the method of the present invention also has excellent effect on the direct deposition of perovskite films.

[0069] The above embodiments of the present application are described in detail, it should be understood that the above described are only specific embodiments of the present application, and are not intended to limit the present application, any modification, supplement or similar way of substitution made within the principle range of the present application, should be included in the protection scope of the present application.

Claims

1. A method for preparing a conformal perovskite thin film, characterized by, The method comprises the following steps: S01, providing a substrate, wherein a surface of the substrate has a surface structure; S02, preparing a perovskite precursor solution by mixing solutes AX and BX2 with a first solvent, immersing the substrate in the perovskite precursor solution, placing a first container containing the substrate and the perovskite precursor solution in a second container containing an anti-solvent, allowing the anti-solvent vapor in the second container to diffuse to the first container, and standing to promote crystallization and deposition of ABX3 perovskite on the substrate; S03, taking out the substrate, spin coating, adding the anti-solvent dropwise, continuing spin coating, and then annealing to obtain a conformal perovskite film; wherein AX is at least one selected from FAI, FABr, FACl, MAI, MACl, MABr, CsI, CsCl and CsBr; and BX2 is at least one selected from PbI2, PbCl2, PbBr2, SnI2, SnCl2 and SnBr2.

2. A method for preparing a conformal perovskite thin film, characterized by, The method comprises the following steps: S11, providing a substrate, wherein a surface of the substrate has a surface structure; S12, dissolving solute A i X, BX2, and a first solvent are formulated into a first precursor solution, the substrate is immersed in the first precursor solution, a first vessel containing the substrate and the first precursor solution is placed in a second vessel containing an anti-solvent, anti-solvent vapor in the second vessel diffuses into the first vessel, and the system is allowed to stand, promoting (A i ) m B n X m+2n crystalline deposition on the substrate; (A i ) m B n X m+2n where 0 < m < 1 and 0 < n < 1. S13, dissolving solute A j X is configured into a second precursor solution with a second solvent, the substrate is taken out for spin coating, the second precursor solution is added dropwise, spin coating is continued, and then annealing treatment is performed to obtain a conformal perovskite film. wherein A i X is selected from at least one of CsI, CsCl, CsBr; BX2is selected from at least one of PbI2, PbCl2, PbBr2, SnI2, SnCl2, SnBr2; A j X is selected from at least one of FAI, FABr, FACl, MAI, MACl, MABr.

3. The method of claim 1 or 2, wherein The first solvent is at least one selected from dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, 2-methoxyethanol, acetonitrile, tetramethyl sulfoxide, propylene carbonate, dimethylacetamide, dimethylaceto urea and N-methyl-2-pyrrolidone.

4. The method of claim 1 or 2, wherein The anti-solvent is at least one selected from dichloromethane, diethyl ether, chlorobenzene, ethyl acetate, anisole, n-hexane and toluene.

5. The method of claim 1 or 2, wherein the method is characterized by, When the anti-solvent vapor in the second container diffuses to the first container, the standing time is 10 min to 2 h.

6. The method of claim 1 or 2, wherein The process parameters of the annealing treatment are 110-150 ℃ for 10-30 min.

7. The method of claim 1, wherein the method is performed in a single chamber. In step S02, the total concentration of the perovskite precursor solution is 1-5 mol / L.

8. The method of claim 2, wherein the method is characterized by: In step S12, the concentration of the first precursor solution is 1.4-2 mol / L.

9. The method of claim 2, wherein the perovskite thin film is deposited by a solution process. In step S13, the second solvent is isopropyl alcohol and / or trifluoroethanol, and the concentration of the second precursor solution is 0.7-1 mol / L.

10. The conformal perovskite film prepared by the method according to any one of claims 1-9 is applied in the field of batteries.

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