Method for preparing perovskite solar cell based on ex-situ method

Abstract

The invention relates to the technical field of photovoltaic devices, in particular to a method for preparing a perovskite solar cell based on an ex-situ method. According to the invention, the prepared MAPbI3 microcrystals are dispersed in an anti-solvent anisole by using a ball milling method, and a dispersion system is more uniform under the action of a dispersant T151 (polyisobutylene succinimide), so that the compactness of the film is improved. On the basis, the microcrystal film is subjected to different post-treatment methods such as a precursor solution and hot pressing to improve the film quality. Wherein the precursor solution post-treatment is mainly characterized in that under the action of a solvent, microcrystals on the surface are dissolved and recrystallized to fill gaps among crystal grains, so that the compactness of the thin film is improved. And the hot-pressing post-treatment can further improve the roughness of the film and reduce the thickness of the film, so that the transmission of carriers is promoted, and the efficiency of the device is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic devices, and in particular to a method for preparing a perovskite solar cell based on a non-in-situ method. Background Art

[0002] Perovskite materials have become the fastest growing solar cells with excellent optoelectronic properties such as adjustable band gap, high absorption coefficient, long carrier diffusion length, and low defect state density. Since it was first reported to be used in solar cells in 2009, perovskite solar cells (PSCs) have developed from the initial 3.8% efficiency to a certified efficiency of 26.1% in just over a decade.

[0003] Although the efficiency of perovskite cells has been rapidly developed and can be compared with that of silicon-based solar cells, the preparation of polycrystalline thin films for efficient perovskite solar cells is currently mainly based on the solution method. The growth of perovskite crystals on the substrate is achieved by adding anti-solvents such as chlorobenzene and ether to promote the volatilization of the solvent and the subsequent annealing process. The growth of crystals in this preparation method is highly disordered, and the poor crystallization quality of the film seriously affects the stability of the film. In order to further improve the performance of polycrystalline perovskite solar cells, researchers have proposed to pre-synthesize crystal powders by grinding or ball milling and disperse them in different anti-solvents. And through simple spreading or powder aerosol deposition (PAD) and other processes, the synthesized MAPbI3 crystal powder is decomposed on the substrate to produce a dense film, so that the perovskite film retains the quality of the crystal to prepare a perovskite solar cell.

[0004] High-quality crystals are the key to ensuring the efficiency of this non-in-situ method for preparing perovskite solar cells, so the preparation of high-quality perovskite crystals is very critical. However, the crystal quality prepared by the above-mentioned mechanical synthesis method is low, and the large-size single crystal preparation method is not only complicated and time-consuming, but also not conducive to large-scale commercial preparation. On the other hand, compared with in-situ growth, this non-in-situ method for preparing perovskite films can retain the high crystal quality of the parent crystal to the greatest extent, but because the contact between the perovskite and the substrate mainly relies on physical effects, the contact with the substrate transport layer is poor, and the charge recombination at the interface is serious, thus affecting the efficiency of the device. In addition, there are many pores between the solid crystal particles, and the roughness of the film is also high, which makes the current density of the device low, making it less efficient and difficult to meet the requirements of large-scale applications. Summary of the invention

[0005] To solve the above problems, the present invention provides a method for preparing a perovskite solar cell based on a non-in-situ method. Under the combined action of the dissolution-recrystallization of microcrystals on the film surface and the crystallization of the precursor solution on the film surface, not only is the densification significantly improved, but also a strong absorption that is highly consistent with that of single crystals in the range of 300–800 nm is achieved. Moreover, the post-processed device after further hot pressing not only has its efficiency increased to 9.023%, but also its performance is significantly improved. It still maintains the intrinsic high stability of the microcrystals, has a high water contact angle of 92.89°, making it more conducive to maintaining the efficiency stability under high humidity conditions. When placed in a high relative humidity environment of 50±5% for more than 5000 h, the device efficiency can still remain above 80% of the original efficiency.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a perovskite solar cell based on a non-in-situ method, comprising the following steps:

[0008] 1) Place the FTO conductive glass on a heated substrate, and prepare a TiO2 dense layer by spray pyrolysis;

[0009] 2) Spin-coat the mesoporous slurry on the obtained TiO2 dense layer and sinter it to prepare a mesoporous TiO2 layer;

[0010] 3) Spray the MAPbI3 microcrystal dispersion system on the obtained mesoporous TiO2 layer and perform annealing treatment to prepare a perovskite active layer;

[0011] The concentration of MAPbI3 microcrystals in the MAPbI3 microcrystal dispersion system is 0.55 M;

[0012] 4) Spray the precursor solution on the obtained perovskite active layer, then place a single-sided polished silicon wafer of the same area and perform hot pressing treatment to prepare a perovskite layer;

[0013] The concentration of methylammonium iodide in the precursor solution is 0.8 M, and the concentration of lead iodide is 0.8 M; the molar ratio of methylammonium iodide and lead iodide in the precursor solution is 1:1;

[0014] 5) Spin-coat the transparent solution on the obtained perovskite layer, and then evaporate and deposit an Au electrode to obtain a perovskite solar cell.

[0015] Preferably, the temperature of the heated substrate in step 1) is 475 °C;

[0016] The specifications of the FTO conductive glass are: area of 2.5 cm × 2.5 cm and thickness of 0.5 cm;

[0017] The conditions for the spray pyrolysis include: using an isopropanol solution with a mass percentage of 75% for spray pyrolysis, spraying one circle every 30 s for a total of 30 - 40 min;

[0018] The preparation method of the 75% isopropanol solution is: adding 515 μL of acetylacetone and 775 μL of diisopropoxybis(acetylacetonato)titanium into 9 mL of isopropanol.

[0019] Preferably, the components of the mesoporous slurry in step 2) are Dyesol-30NR-D and absolute ethanol, and the mass ratio of Dyesol-30NR-D to absolute ethanol is 1:7;

[0020] The average particle size of the Dyesol-30NR-D is 30 nm;

[0021] The conditions for spin-coating the mesoporous slurry include: spin-coating at 4000 rpm for 20 s.

[0022] Preferably, the conditions for sintering in step 2) include: a temperature of 500 °C and a time of 12 h.

[0023] Preferably, the number of sprays of the MAPbI3 microcrystal dispersion system in step 3) is 2 times, the interval time is 10 s, and the area ratio of the amount of each spray to the area of the mesoporous TiO2 layer is 50 μL:2.5 cm × 2.5 cm.

[0024] Preferably, the preparation method of the MAPbI3 microcrystal dispersion system in step 3) includes: mixing MAPbI3 microcrystals with polyisobutylene succinimide and dispersing them in anisole by ball milling;

[0025] The molar ratio of the MAPbI3 microcrystals to the volume of anisole is 0.55 mmol:1 ml; the mass percentage of polyisobutylene succinimide in the MAPbI3 microcrystal dispersion system is 0.95%.

[0026] Preferably, the conditions for the annealing treatment in step 3) include: a time of 30 min, a temperature of 120 °C, the angle between the spray gun head and the horizontal position is 45°, the spray gun is 10 - 15 cm above the substrate, and nitrogen is used as the carrier gas with a carrier gas pressure of 35 Psi.

[0027] Preferably, the area ratio of the amount of the precursor solution used each time to the area of the perovskite active layer in step 4) is 20 μL:2.5 cm × 2.5 cm, and it is sprayed 2 times in total with an interval time of 10 s;

[0028] The conditions for the hot pressing treatment include: a temperature of 150 °C, a pressure of 150 MPa, and a time of 2 h.

[0029] Preferably, the preparation method of the transparent solution in step 5) includes: dissolving 72.3 mg of spiro-OMeTAD in 1 mL of chlorobenzene, and then adding 17.5 μL of an acetonitrile solution of Li-TFSI and 28 μL of 4-tert-butylpyridine;

[0030] The concentration of Li-TFSI in the acetonitrile solution of Li-TFSI is 520 mg / mL;

[0031] The volume ratio of the transparent solution to the area of the perovskite layer is 50 μL: 2.5 cm × 2.5 cm;

[0032] The spin-coating time of the transparent solution is 20 s.

[0033] Preferably, the thickness of the Au electrode in step 5) is 80 nm.

[0034] The present invention uses a ball milling method to disperse the prepared MAPbI3 microcrystals in the antisolvent anisole, and under the action of the dispersant T151 (polyisobutylene succinimide), the dispersion system becomes more uniform, thereby improving the denseness of the film. On this basis, different post-treatment methods such as precursor solution and hot pressing are carried out on the microcrystal film to improve the film quality. Among them, the post-treatment of the precursor solution mainly dissolves and recrystallizes the surface microcrystals under the action of the solvent to fill the gaps between the grains and improve the denseness of the film. The hot pressing post-treatment can further improve the roughness of the film and reduce the film thickness, promote the transport of carriers, and significantly improve the efficiency of the device.

[0035] The beneficial effects of the present invention:

[0036] 1. In terms of process: The prepared microcrystals are directly dispersed in the antisolvent dispersion system. The process preparation is simple and does not require the participation of toxic solvents, making it more suitable for large-scale commercial preparation.

[0037] 2. In terms of effect: Under the combined action of the dissolution-recrystallization of the surface microcrystals of the film and the crystallization of the precursor solution on the film surface, not only the denseness is significantly improved, but also it has a strong absorption in the full range that is highly consistent with that of single crystals in the range of 300–800 nm. And after the further hot pressing post-treatment, the device not only has its efficiency increased to 9.023%, but also its performance is significantly improved. It still maintains the intrinsic high stability of the microcrystals, has a high water contact angle of 92.89°, making it more conducive to maintaining the efficiency stability under high humidity conditions. When placed in a high relative humidity environment of 50 ± 5% for more than 5000 h, the device efficiency can still remain above 80% of the original efficiency. Description of the Drawings

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments.

[0039] Figure 1 XRD patterns of the comparative examples and experimental examples;

[0040] Figure 2 AFM images of the comparative examples and experimental examples;

[0041] Figure 3 Summary of the forward and reverse scans of the perovskite solar cells of the comparative examples and experimental examples;

[0042] Figure 4 (a) Water contact angle of the experimental example and (b) XRD pattern of the thin film of the experimental example placed under the condition of 70 ± 5% relative humidity for 60 days. Detailed implementation manners

[0043] The present invention provides a method for preparing a perovskite solar cell based on a non-in-situ method, comprising the following steps:

[0044] 1) Place the FTO conductive glass on a heating substrate, and prepare a TiO2 dense layer by spray pyrolysis;

[0045] 2) Spin-coat the mesoporous slurry on the obtained TiO2 dense layer and sinter it to prepare a mesoporous TiO2 layer;

[0046] 3) Spray the MAPbI3 microcrystal dispersion system on the obtained mesoporous TiO2 layer and perform annealing treatment to prepare a perovskite active layer;

[0047] The concentration of MAPbI3 microcrystals in the MAPbI3 microcrystal dispersion system is 0.55 M;

[0048] 4) Spray the precursor solution on the obtained perovskite active layer, then place a single-sided polished silicon wafer of the same area and perform hot pressing treatment to prepare a perovskite layer;

[0049] The concentration of methylammonium iodide in the precursor solution is 0.8 M, and the concentration of lead iodide is 0.8 M; the molar ratio of methylammonium iodide and lead iodide in the precursor solution is 1:1;

[0050] 5) Spin-coat the transparent solution on the obtained perovskite layer, and then evaporate the Au electrode to obtain a perovskite solar cell.

[0051] In the present invention, the FTO conductive glass is placed on a heating substrate, and a TiO2 dense layer is prepared by spray pyrolysis. In the present invention, the temperature of the heating substrate is preferably 475 °C. In the present invention, the specifications of the FTO conductive glass are preferably as follows: the area is 2.5 cm × 2.5 cm, and the thickness is 0.5 cm. In the present invention, the conditions of the spray pyrolysis preferably include: using an isopropanol solution with a mass percentage of 75% for spray pyrolysis, spraying one circle every 30 s for a total of 30 - 40 min; the preparation method of the 75% isopropanol solution is: adding 515 μL of acetylacetone and 775 μL of diisopropoxybis(acetylacetonato)titanium to 9 mL of isopropanol. In the present invention, there is no special stipulation on the material of the heating substrate. The heating substrate is a heated hot stage, which has no influence on the process and is not in the structure.

[0052] In the present invention, the mesoporous slurry is spin-coated on the obtained TiO2 dense layer and sintered to prepare a mesoporous TiO2 layer. In the present invention, the components of the mesoporous slurry are preferably: Dyesol-30NR-D and absolute ethanol, and the mass ratio of Dyesol-30NR-D to absolute ethanol is 1:7; the average particle size of Dyesol-30NR-D is 30 nm. In the present invention, the conditions of the spin-coating of the mesoporous slurry preferably include: spin-coating at 4000 rpm for 20 s. In the present invention, the conditions of the sintering preferably include: the temperature is 500 °C and the time is 12 h.

[0053] In the present invention, the MAPbI3 microcrystal dispersion system is sprayed on the obtained mesoporous TiO2 layer and annealed to prepare a perovskite active layer; the concentration of MAPbI3 microcrystals in the MAPbI3 microcrystal dispersion system is 0.55 M. In the present invention, the number of spraying times of the MAPbI3 microcrystal dispersion system is preferably 2 times, the interval time is preferably 10 s, and the area ratio of the spraying amount per time to the area of the mesoporous TiO2 layer is preferably 50 μL:2.5 cm × 2.5 cm. In the present invention, the preparation method of the MAPbI3 microcrystal dispersion system preferably includes: mixing MAPbI3 microcrystals with polyisobutylene succinimide and dispersing them in anisole by ball milling; the molar ratio of MAPbI3 microcrystals to the volume of polyisobutylene succinimide and the volume of anisole is preferably 0.55 mmol:1 ml; the mass percentage of polyisobutylene succinimide in the MAPbI3 microcrystal dispersion system is 0.95%. In the present invention, the conditions of the annealing treatment preferably include: the time is 30 min, the temperature is 120 °C, the angle between the spray gun head used and the horizontal position is maintained at 45°, the spray gun is 10 - 15 cm above the substrate, and nitrogen is used as the carrier gas with a carrier gas pressure of 35 Psi.

[0054] The precursor solution of the present invention is sprayed on the obtained perovskite active layer, and then a single-sided polished silicon wafer of the same area is placed and then hot-pressed to prepare a perovskite layer; the concentration of methylammonium iodide in the precursor solution is 0.8 M, and the concentration of lead iodide is 0.8 M; the molar ratio of methylammonium iodide and lead iodide in the precursor solution is 1:1. In the present invention, the area ratio of the amount of the precursor solution used each time to the area of the perovskite active layer is preferably 20 μL: 2.5 cm × 2.5 cm, and it is sprayed 2 times with an interval of 10 s. In the present invention, the conditions of the hot pressing treatment preferably include: temperature 150 °C, pressure 150 MPa, and time 2 h.

[0055] The transparent solution of the present invention is spin-coated on the obtained perovskite layer, and then an Au electrode is evaporated to obtain a perovskite solar cell. In the present invention, the preparation method of the transparent solution preferably includes: dissolving 72.3 mg of spiro-OMeTAD in 1 mL of chlorobenzene, and then adding 17.5 μL of an acetonitrile solution of Li-TFSI and 28 μL of 4-tert-butylpyridine. In the present invention, the concentration of Li-TFSI in the acetonitrile solution of Li-TFSI is preferably 520 mg / mL. In the present invention, the volume ratio of the transparent solution to the area of the perovskite layer is preferably 50 μL: 2.5 cm × 2.5 cm. In the present invention, the spin-coating time of the transparent solution is preferably 20 s. In the present invention, the thickness of the Au electrode is preferably 80 nm.

[0056] To further illustrate the present invention, the present invention will be described in detail below in conjunction with embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0057] Example 1

[0058] Structure description:

[0059] Experimental example (PS / HP): The battery structures used are all mesoporous n-i-p type solar cells, and the device structure is FTO / c-TiO2 / m-TiO2 / perovskite active layer / Spiro-OMeTAD / Au. Among them, FTO: the thickness of the glass is 0.5 cm, the c-TiO2 layer (40 - 50 nm), the m-TiO2 layer (200 - 300 nm), the perovskite active layer (500 - 800 nm), the thickness of the Spiro-OMeTAD layer is rarely mentioned, and Au (80 nm).

[0060] Preparation of the dispersion system: 1.023 g of MAPbI3 microcrystals are dispersed in 3 ml of anisole to prepare a 0.55 M dispersion system. T151 is added as a dispersant in the dispersion system, and the mass percentage content is 0.95%, and ball milling is carried out overnight to prepare a uniform dispersion system.

[0061] Preparation of the electron transport layer ( / c-TiO2 / m-TiO2): Place the cleaned FTO conductive glass (with an area of 2.5 cm × 2.5 cm and a thickness of 0.5 cm) on a heating substrate at 475 °C, and prepare the TiO2 dense layer (c-TiO2) by spray pyrolysis. Spin-coat the prepared mesoporous slurry onto the c-TiO2-FTO glass substrate that has cooled naturally to room temperature. After spin-coating, place it in a muffle furnace and sinter it overnight at 500 °C to prepare the mesoporous TiO2 layer (m-TiO2).

[0062] The conditions for spray pyrolysis are as follows: Use an isopropanol solution with a mass percentage of 75% for spray pyrolysis. Spray one circle every 30 s for a total of 30 - 40 min;

[0063] The preparation method of the 75% isopropanol solution is as follows: Add 515 μL of acetylacetone and 775 μL of titanium diisopropoxide bis(acetylacetonate) to 9 mL of isopropanol;

[0064] Preparation of the perovskite active layer: Spray the dispersion system twice onto the mesoporous TiO2 layer, with a 10 s interval between the two spraying operations. The amount of the dispersion system used for each spraying is 50 μL. After the two sprayings, place the obtained perovskite thin film on a hot plate at 120 °C for post-annealing treatment for 30 min to prepare the perovskite active layer. The angle between the spray gun head and the horizontal position is 45°, the spray gun is 10 - 15 cm above the substrate, and nitrogen is used as the carrier gas with a carrier gas pressure of 35 Psi.

[0065] Post-treatment of the active layer: Dissolve CH3NH3I and PbI2 in GVL according to a molar ratio of 1:1 to prepare precursor solutions with different concentrations. Perform post-treatment by spraying the precursor solutions with different concentrations at a substrate temperature of 100 °C. The amount of the solution used for each spraying is 20 μL, and a total of 2 sprays are performed, with an interval of 20 - 30 s each time. Perform hot pressing post-treatment on the perovskite thin film after the above-mentioned post-treatment with the precursor solution. Place a single-sided polished silicon wafer with an area of 2.5 cm × 2.5 cm equal to that of the prepared thin film on it, and perform hot pressing at different temperatures for 2 h with a hot pressing pressure of 150 MPa; After the subsequent hot pressing treatment, the perovskite active layer is obtained.

[0066] Preparation of the Spiro-OMeTAD layer: Dissolve 72.3 mg of Spiro-OMeTAD in 1 mL of chlorobenzene, then add 17.5 μL of the acetonitrile solution of Li-TFSI (520 mg mL-1) and 28 μL of 4-tert-butylpyridine (TBP) and shake well. Take 50 μL of the uniformly mixed clear and transparent solution and spin-coat it dynamically onto the perovskite active layer for 20 s.

[0067] Preparation of Au: Place the thin film in a high-vacuum coating glove box system, and deposit an Au electrode with a thickness of 80 nm on the hole transport layer;

[0068] Comparative example

[0069] The perovskite layer in the control is not post-treated, and the preparation of other layers is the same as that in Example 1.

[0070] Results:

[0071] As Figure 1 shown. The characteristic diffraction peaks at positions 14.1°, 28.3°, and 31.7° correspond to the (110), (220), and (310) crystal planes of MAPbI3, respectively. Compared with the untreated thin film, the PS / HP thin film shows higher characteristic diffraction peak intensity, and the relative intensities of the (110) and (310) crystal planes also increase from 0.85 to 5.91, further proving that the post-treatment can not only help improve the crystallinity of the thin film but also contribute to the preferential growth of the perovskite thin film along the (110) crystal plane perpendicular to the substrate direction.

[0072] The perovskite particles deposited on the substrate have too large crystal particle size and uneven dispersion, and the surface roughness is too large, and the surface of the perovskite thin film is frosted. After treatment with the precursor solution, the surface grains are redissolved and recrystallized under the action of the solvent, and under the combined action of annealing and crystallization of the precursor solution, the surface holes are filled to promote surface uniformity. At the same time, under the further action of the hot pressing post-treatment, the crystal particles increase, the surface roughness is reduced, and the perovskite thin film presents a mirror surface.

[0073] As Figure 3 shown. After the post-treatment, due to the improvement of the surface densification and crystallization quality of the thin film, the density of defect states is significantly reduced, so that JSC increases from 3.35 mA cm -2 to 14.32 mA cm -2 , and JSC is significantly improved. And the improvement of the thin film morphology and the reduction of the thickness after the post-treatment improve the contact between the perovskite layer and the hole transport layer, which helps VOC increase from 0.77 V to 0.98 V. Thanks to the significant increase in the open-circuit voltage and current density, the device efficiency also increases from 1.493% to 8.655%. The HI of the PS / HP device is 2.43, and the hysteresis factor is significantly reduced compared with the control group (20.3), further proving that the improvement of the PS / HP thin film quality reduces the defect density inside the perovskite active layer and helps the transport of carriers under illumination conditions.

[0074] The stability of the battery is an important reason restricting the application of perovskite batteries. In order to study the stability of the post-treated devices under optimal conditions, the water contact angle of the treated thin film was tested as Figure 4As shown, the water contact angle of the treated film is 92.89°. The higher contact angle further proves that it helps to resist moisture erosion. The treated film was placed in a high relative humidity environment of 70±5% for 60 days, and its XRD changes are as shown in Figure 4 shown in b. No decomposition peak of PbI2 was observed in the film after 60 days, indicating its excellent stability in a high humidity environment.

[0075] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments according to these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a perovskite solar cell based on the non-in-situ method, characterized in that, It includes the following steps: 1) Place the FTO conductive glass on a heating substrate and prepare a TiO2 dense layer by spray pyrolysis; 2) Spin-coat the mesoporous slurry on the obtained TiO2 dense layer and sinter it to prepare a mesoporous TiO2 layer; 3) Spray the MAPbI3 microcrystal dispersion system on the obtained mesoporous TiO2 layer and perform annealing treatment to prepare a perovskite active layer; The concentration of MAPbI3 microcrystals in the MAPbI3 microcrystal dispersion system is 0.55 M; 4) Spray the precursor solution on the obtained perovskite active layer, then place a single-sided polished silicon wafer of the same area and perform hot pressing treatment to prepare a perovskite layer; The concentration of methylammonium iodide in the precursor solution is 0.8 M, and the concentration of lead iodide is 0.8 M; The molar ratio of methyl potassium iodide to lead iodide in the precursor solution is 1:1; 5) Spin-coat the transparent solution on the obtained perovskite layer, and then evaporate and deposit an Au electrode to obtain a perovskite solar cell.

2. The method according to claim 1, wherein The temperature of the heating substrate in step 1) is 475 °C; The specifications of the FTO conductive glass are: the area is 2.5 cm × 2.5 cm, and the thickness is 0.5 cm; The conditions for spray pyrolysis include: using an isopropanol solution with a mass percentage of 75% for spray pyrolysis, spraying one circle every 30 s, for a total of 30 - 40 min; The preparation method of the 75% isopropanol solution is: add 515 μL of acetylacetone and 775 μL of diisopropoxybis(acetylacetonato)titanium to 9 mL of isopropanol.

3. The method according to claim 1, wherein The components of the mesoporous slurry in step 2) are: Dyesol-30NR-D and absolute ethanol, and the mass ratio of Dyesol-30NR-D to absolute ethanol is 1:7; The average particle size of Dyesol-30NR-D is 30 nm; The conditions for spin-coating the mesoporous slurry include: spin-coating at 4000 rpm for 20 s.

4. The method according to claim 1, characterized in that, The sintering conditions in step 2) include: the temperature is 500 °C and the time is 12 h.

5. The method according to claim 1, wherein The number of times of spraying the MAPbI3 microcrystal dispersion system in step 3) is 2 times, the interval time is 10 s, and the ratio of the spraying amount per time to the area of the mesoporous TiO2 layer is 50 μL:2.5 cm × 2.5 cm.

6. The method according to claim 1, wherein The preparation method of the MAPbI3 microcrystal dispersion system in step 3) includes: mixing MAPbI3 microcrystals with polyisobutylene succinimide and dispersing them in anisole by ball milling; The molar ratio of MAPbI3 microcrystals to the volume of anisole is 0.55 mmol:1 ml; the mass percentage of polyisobutylene succinimide in the MAPbI3 microcrystal dispersion system is 0.95%.

7. The method according to claim 1, wherein The annealing treatment conditions in step 3) include: the time is 30 min, the temperature is 120 °C, the angle between the spray gun head and the horizontal position is maintained at 45°, the spray gun is 10 - 15 cm above the substrate, and nitrogen is used as the carrier gas with a carrier gas pressure of 35 Psi.

8. The method according to claim 1, wherein The amount of the precursor solution used each time in step 4) and the ratio to the area of the perovskite active layer is 20 μL:2.5 cm × 2.5 cm, and it is sprayed 2 times in total with an interval time of 10 s; The conditions for the hot pressing treatment include: temperature of 150 °C, pressure of 150 MPa, and time of 2 h.

9. The method according to claim 1, wherein The preparation method of the transparent solution in step 5) includes: dissolving 72.3 mg of spiro-OMeTAD in 1 mL of chlorobenzene, and then adding 17.5 μL of the acetonitrile solution of Li-TFSI and 28 μL of 4-tert-butylpyridine; The concentration of Li-TFSI in the acetonitrile solution of Li-TFSI is 520 mg / mL; The volume ratio of the transparent solution to the area of the perovskite layer is 50 μL: 2.5 cm × 2.5 cm; The spin-coating time of the transparent solution is 20 s.

10. The method according to claim 1, wherein The thickness of the Au electrode in step 5) is 80 nm.

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