Preparation method and application of shape-preserving perovskite thin film

Abstract

The invention discloses a preparation method and application of a conformal perovskite film, and belongs to the technical field of perovskite photoelectric materials.According to the method, a solution method is used for film formation in the whole technological process, an anti-solvent is gradually volatilized in a gas phase form to enter a precursor solution to promote film crystallization and deposition, and the film is formed. According to the method, perovskite thin films can be grown on various substrates including textured silicon, an ABX3 perovskite material can be directly deposited on the substrate to form a film, and (Ai) mBnXm + 2n can be firstly deposited on the substrate and then a solution with the solute being AjX is spin-coated to form the film. The preparation method provided by the invention has the advantages of mild conditions, no need of high-temperature, vacuum and other environments, simple preparation process, low cost and easiness in large-scale production, and can be used for depositing a high-quality conformal perovskite thin film on a substrate with relatively large surface fluctuation, such as textured silicon, so that the whole textured structure is completely covered, and carrier transmission is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of perovskite photoelectric materials, and specifically relates to a preparation method of a conformal perovskite film and an application thereof. Background Art

[0002] In today's era, energy problems are becoming increasingly serious, and photovoltaic technology is becoming more and more popular. The most widely used solar cell is crystalline silicon solar cell. Although crystalline silicon solar cells have the characteristics of relatively low manufacturing cost, mature technical route, and easy large-scale production, their current photoelectric conversion efficiency is close to their theoretical limit. Compared with crystalline silicon solar cells, perovskite solar cells have lower manufacturing costs, outstanding performance, and simple process. In particular, their photoelectric conversion efficiency has now exceeded 25%, and it has attracted more and more attention. The light-absorbing layer of perovskite solar cells is an organic-inorganic halide perovskite material, whose components are ABX3, including A-site cations, B-site cations, and X anions.

[0003] Although perovskite materials are developing rapidly, and the highest conversion efficiency of single-junction perovskite solar cells is 25.8%, it will eventually be limited by the Shockley-Queisser limit, and the room for improving conversion efficiency will gradually shrink as it approaches this limit. In order to further improve the photoelectric conversion efficiency of solar cells, crystalline silicon / perovskite stacked solar cells have become a very feasible solution. Perovskite solar cells have a high absorption rate only in the visible light spectrum region, while crystalline silicon solar cells have a wider absorption spectrum (300-1200nm). The two can complement each other to fully utilize solar energy. For example, a Chinese patent document with publication number CN115621331A discloses a perovskite stacked solar cell, including a silicon bottom cell and a perovskite top cell, wherein the top surface of the silicon bottom cell is sequentially stacked with a silicon oxide layer and a P-type doped amorphous silicon layer, and the P-type doped amorphous silicon layer is located on the bottom surface of the perovskite top cell; the perovskite light-absorbing layer of the perovskite top cell contains alkali metal ions; the P-type doped amorphous silicon layer is a disordered silicon single substance with many defects, which facilitates the movement of carriers, and the synergy of the silicon oxide layer and the P-type doped amorphous silicon layer can increase the tunneling of carriers.

[0004] However, the upper surface of silicon wafers used to manufacture crystalline silicon cells has large fluctuations after texturing, so the conformal growth of perovskite films on the upper surface of silicon wafers is a difficult problem that needs to be solved urgently. Otherwise, there will be many holes and gaps between the obtained perovskite film and the silicon wafer, which will have a great impact on carrier transport. To solve this problem, there are currently two solutions in the field. One is to grow a perovskite film on silicon wafers using a vacuum evaporation process with good conformality, 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 relatively complicated, limiting its further commercial application; the other is to use a solution method to grow a perovskite film on a silicon wafer with a thickness larger than the pyramid size on the silicon wafer surface, but increasing the film thickness of the perovskite will increase the resistance of the battery device and will also affect the photoelectric performance of the crystalline silicon / perovskite stacked solar cell.

[0005] A Chinese patent document with publication number CN114335359A discloses a method for making a perovskite film, the process of which includes: providing a substrate, the surface of which has a velvet structure; forming a metal halide skeleton layer on the substrate with the velvet structure, the metal halide skeleton layer conformally covering the velvet structure; forming a perovskite light absorption layer conformally on the metal halide skeleton layer with the velvet structure; wherein the metal halide skeleton layer plays an anchoring role, so that the subsequently formed perovskite light absorption layer can form a layer of perovskite film along with the undulations of the velvet structure. However, in this method, an additional metal halide skeleton layer needs to be introduced, and the steps are relatively cumbersome. Summary of the invention

[0006] The present invention provides a method for preparing a conformal perovskite film. The whole process uses a solution method to form a film with mild conditions and does not require a high temperature, vacuum or other environment. It can deposit a high-quality conformal perovskite film on a substrate with large surface undulations such as suede silicon, completely covering the entire suede structure.

[0007] The following two technical solutions are specifically adopted:

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

[0009] S01, providing a substrate, wherein the surface of the substrate has a suede structure;

[0010] S02, preparing a perovskite precursor solution with solutes AX and BX2 and a first solvent, immersing a 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 into the first container, and allowing the solution to stand to promote crystallization and deposition of ABX3 perovskite on the substrate;

[0011] S03, taking out the substrate, spin coating, adding anti-solvent, and then annealing to obtain a conformal perovskite film.

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

[0013] The method of the present invention uses a solution method for film formation in the entire process. During the deposition of 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 evenly attached to the velvet substrate. Further, in the subsequent spin coating process, as the solvent evaporates, the crystals grow to form a 500-800nm ​​thick perovskite film.

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

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

[0016] In step S02, the anti-solvent is at least one of dichloromethane, 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 time for the anti-solvent vapor in the second container to diffuse into the first container is 10 min-2 h.

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

[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 suede structure;

[0022] S12, solute Ai X, BX2 and a first solvent are prepared into a first precursor solution, the substrate is immersed in the first precursor solution, the first container containing the substrate and the first precursor solution is placed in a second container containing an anti-solvent, the anti-solvent vapor in the second container diffuses into the first container, and the solution is allowed to stand to promote (A i ) m B n X m+2n Crystalline deposition on substrate; (A i ) m B n X m+2n In, 0<m<1, 0<n<1;

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

[0024] Among them, 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 entire process of this method uses a solution method to form a film. During the deposition of some perovskite components in an anti-solvent atmosphere, as the anti-solvent gradually penetrates into the precursor solution, the saturation of the solution increases, promoting the rapid formation of a large number of crystal nuclei. The crystal nuclei in the solution can be evenly attached to the velvet substrate. Further in the subsequent spin coating process, as the solvent evaporates, the crystals grow to form a 500-800nm ​​thick perovskite film.

[0026] Preferably, the substrate is a suede 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, dimethylpropylene urea, and N-methyl-2-pyrrolidone.

[0028] In step S12, the anti-solvent is at least one of dichloromethane, 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 into the first container is 10 min-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, spin coating is performed on a coating machine. Specifically, the process parameters of step S13 are: take out the substrate and spin coat at 1000-3000rpm for 10-60s, add 30-100μL of the second precursor solution, and continue to spin coat at 1000-3000rpm for 30-60s; the process parameters of annealing treatment are: annealing at 110-150℃ for 10-30min.

[0033] The present invention also provides the application of the conformal perovskite film prepared by the method for preparing the conformal perovskite film in the field of batteries, especially in the field of stacked batteries.

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

[0035] (1) The method for preparing the conformal perovskite film provided by the present invention uses a solution method throughout the entire process, does not require a high temperature, vacuum or other environment, is easy to dope, has a simple preparation process, is low cost, can achieve large-area deposition, and is easy to mass produce.

[0036] (2) The method for preparing a conformal perovskite film provided by the present invention can deposit a high-quality conformal perovskite film on a substrate with a large surface undulation such as suede silicon. The surface undulation of suede silicon can reach several microns, completely covering the entire suede structure, which is convenient for carrier transport. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0038] Figure 2 This is the XRD diagram of the conformal perovskite film prepared in Example 1.

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

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

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

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

[0043] Figure 7 This is the XRD diagram of the conformal perovskite film prepared in Example 3.

[0044] Figure 8 This is a cross-sectional SEM image of the conformal perovskite film prepared in Example 3.

[0045] Fig. 9 This is the SEM image of the perovskite film prepared in Comparative Example 2. DETAILED DESCRIPTION

[0046] The present invention is further illustrated below in conjunction with the examples and accompanying drawings. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0047] Example 1

[0048] Method 2 was used to prepare perovskite films on textured silicon substrates using dichloromethane (DCM) as an anti-solvent, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) as a first solvent, and isopropyl alcohol (IPA) as a second solvent.

[0049] (1) Providing a suede silicon substrate;

[0050] (2) At room temperature, CsBr, PbBr2 and PbI2 were dissolved in a first solvent (the volume ratio of DMF and DMSO was 193:7), stirred evenly and fully dissolved, and a first precursor solution with a total concentration of 1.4 M was prepared; 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 an anti-solvent dichloromethane, and the anti-solvent vapor in the second container diffused into the first container, and the deposition was allowed to stand for 15 minutes to promote the deposition of Cs 0.05 PbI 1.6 Br 0.45 Crystalline deposition on a substrate;

[0051] (3) The solutes FAI and MABr were dissolved in isopropanol and stirred evenly to obtain a second precursor solution with a concentration of 0.7 M. The substrate was taken out and placed on a spin coater, first rotated at a speed of 1500 rpm for 30 seconds, and then 50 μL of the second precursor solution was dropped into the spin coater, and then rotated at a speed of 1800 rpm for 40 seconds. After the spin coating was completed, the substrate was placed on a hot plate at 90°C for 1 minute, and annealed at 150°C for 10 minutes at 30-40% RH to obtain a conformal FAI. 0.74 MA 0.21 Cs 0.05 PbI 2.34 Br0.66 Perovskite thin films.

[0052] Comparative Example 1

[0053] The methods of step (1) and step (2) in comparative example 1 are the same as those in example 1, except that in step (3):

[0054] The substrate was taken out and placed on a coater, first rotated at 1000 rpm for 3 seconds, then at 4000 rpm for 60 seconds, and 300 μL of ethyl acetate antisolvent was dropped in the 10th second after the start of spin coating; after spin coating, the substrate was placed on a hot stage at 70°C for 1 minute, and then annealed at 130°C for 30 minutes.

[0055] Example 2

[0056] In this embodiment, the method for preparing a conformal perovskite film is different from that in Embodiment 1 only in that the total concentration of the first precursor solution is 2 M, the total concentration of the second precursor solution is 1 M, the second solvent is trifluoroethanol, and the deposition is allowed to stand for 20 minutes.

[0057] Example 3

[0058] Method 1 was used to prepare perovskite films on a textured silicon substrate using dichloromethane (DCM) and ethyl acetate as anti-solvents, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) as first solvents in a ratio of 4:1.

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

[0060] (2) At room temperature, CsI, PbBr2, PbI2, FAI, and MABr were dissolved in a first solvent, stirred evenly and fully dissolved to prepare a 2M total concentration perovskite precursor solution (the molar ratio of AX and BX2 was 1:1), and the substrate was immersed in the perovskite precursor solution (the surface of the substrate to be deposited did not contact the inner wall of the first container); then the first container containing the substrate and the perovskite precursor solution was placed in a second container containing an anti-solvent dichloromethane, and the anti-solvent vapor in the second container diffused into the first container, and the deposition was allowed to stand for 20 minutes to promote the deposition of Cs 0.05 FA 0.6 MA 0.35 PbI 1.65 Br 1.35 The perovskite is crystallized and deposited on the substrate;

[0061] (3) The substrate was taken out and placed on a coating machine, first rotated at 1000 rpm for 5 s, then at 4000 rpm for 60 s, and 300 μL of anti-solvent ethyl acetate was added 10 s after the start of rotation; after the spin coating was completed, the substrate was placed on a hot plate at 70°C for 1 min, and then annealed on a hot plate at 150°C for 10 min to obtain a 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 anti-solvent ethyl acetate is not added dropwise.

[0064] Example 4

[0065] In this embodiment, the method for preparing a conformal perovskite film is different from that in Embodiment 3 only in that the total concentration of the perovskite precursor solution is 2.5 M and the deposition is allowed to stand for 25 minutes.

[0066] Sample analysis

[0067] The morphology of the conformal perovskite film prepared in Example 1 under a scanning electron microscope is as follows: Figure 1 As shown, the cross-sectional morphology is Figure 3 As shown, the X-ray diffraction pattern is as Figure 2 As shown, the morphology of the textured silicon substrate used is as follows Figure 4 As shown in FIG. 1 , it can be seen that the conformal perovskite film and the pyramids on the velvet silicon substrate have excellent conformal properties, and no velvet silicon pyramids are exposed, indicating that the method of the present invention successfully deposits a conformal perovskite film. The SEM image of the perovskite film in Comparative Example 1 is shown in FIG. Figure 5 As shown, the pyramid tips of the velvet silicon substrate are clearly exposed, indicating that the method of the present invention has a better effect in depositing perovskite films.

[0068] The morphology of the conformal perovskite film prepared in Example 3 under a scanning electron microscope is as follows: Figure 6 As shown, the cross-sectional morphology is Figure 8 As shown, the X-ray diffraction pattern is as Figure 7 As shown, the textured silicon substrate used is the same as that in Example 1. The morphology of the perovskite film in Comparative Example 2 is as follows Fig. 9 Compared with Comparative Example 2, the perovskite film in Example 3 has excellent conformality and no pyramid tip is exposed, indicating that the method of the present invention is also very effective in directly depositing the perovskite film.

[0069] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

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

2. A method for preparing a conformal perovskite film, characterized in that: The following steps are involved: S11, providing a substrate, wherein a surface of the substrate has a suede structure; S12, solute A i X, BX2 and a first solvent are prepared into a first precursor solution, the substrate is immersed in the first precursor solution, the first container containing the substrate and the first precursor solution is placed in a second container containing an anti-solvent, the anti-solvent vapor in the second container diffuses into the first container, and the solution is allowed to stand to promote (A i ) m B n X m+2n Crystalline deposition on substrate; (A i ) m B n X m+2n In, 0<m<1, 0<n<1; S13, solute A j X and a second solvent are mixed to form a second precursor solution, the substrate is taken out and spin-coated, the second precursor solution is added dropwise, the spin coating is continued, and then annealing is performed to obtain a conformal perovskite film; Among them, 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.

3. The method for preparing a conformal perovskite thin film according to claim 1 or 2, characterized in that: The first solvent is at least one of dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, 2-methoxyethanol, acetonitrile, tetramethyl sulfoxide, propylene carbonate, dimethylacetamide, dimethylpropylene urea, and N-methyl-2-pyrrolidone.

4. The method for preparing a conformal perovskite thin film according to claim 1 or 2, characterized in that: The anti-solvent is at least one of dichloromethane, ether, chlorobenzene, ethyl acetate, anisole, n-hexane and toluene.

5. The method for preparing a conformal perovskite thin film according to claim 1 or 2, characterized in that: When the anti-solvent vapor in the second container diffuses into the first container, the standing time is 10 minutes to 2 hours.

6. The method for preparing a conformal perovskite thin film according to claim 1 or 2, characterized in that: The process parameters of the annealing treatment are: annealing at 110-150°C for 10-30 minutes.

7. The method for preparing a conformal perovskite thin film according to claim 1, characterized in that: In step S02, the total concentration of the perovskite precursor solution is 1-5 mol / L.

8. The method for preparing a conformal perovskite thin film according to claim 2, characterized in that: In step S12, the concentration of the first precursor solution is 1.4-2 mol / L.

9. The method for preparing a conformal perovskite thin film according to claim 2, characterized in that: 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.

10. Application of the conformal perovskite film prepared by the method for preparing the conformal perovskite film according to any one of claims 1 to 9 in the field of batteries.

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