Post-processing methods for FAPbI3 perovskite thin films and their applications
By introducing MACl vapor to form an intermediate phase in the preparation of FAPbI3 perovskite thin films via co-evaporation and then annealing, the problems of excessive FAI and poor crystallinity were solved, thereby improving the photoelectric performance and crystallinity of photovoltaic devices.
Patent Information
- Application Number
- CN202610540575.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-22
- Publication Date
- 2026-07-31
AI Technical Summary
In the prior art, the excessive use of FAI and poor perovskite crystallization during the co-evaporation method for preparing FAPbI3 perovskite thin films lead to reduced device efficiency, and there is a lack of effective microscopic characterization and solutions.
A post-treatment method was adopted to introduce MACl into the co-evaporated FAPbI3 perovskite film in vapor form to form the intermediate phases MAPbCl3 and Pb3I8. The annealing treatment was then used to transform the phase into black α-FAPbI3, which eliminated excess FAI, promoted grain recrystallization, and improved crystallinity.
It effectively eliminates the impact of excessive FAI on the device, improves the photoelectric performance of the photovoltaic device, expands the tolerance range of the PbI2 and FAI evaporation rate ratio, and improves the crystal morphology and crystallinity.
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Figure CN122497267A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photovoltaic technology, specifically relating to a post-processing method for FAPbI3 perovskite thin films, the perovskite thin films prepared therefrom, and their applications. Background Technology
[0002] Currently, the highest efficiency of single-junction perovskite solar cells reaches 25.5%, while the highest efficiency of perovskite-silicon tandem cells has reached 29.5%, with significant room for improvement. To combine with the traditional double-sided texturing process for silicon, the one-step evaporation method for perovskite preparation can uniformly coat the perovskite layer on the textured surface. In contrast, traditional solution spin coating and blade coating methods struggle to achieve uniform deposition on textured surfaces, requiring further processing of the silicon wafer. This leads to a significant decrease in the original silicon wafer efficiency and increases process complexity and cost.
[0003] Meanwhile, the co-evaporation method for preparing FAPbI3 requires precise control of the evaporation rate ratio of FAI (HC(NH2)2I) and PbI2, but this is easily affected by room temperature, cold pump temperature, substrate temperature, and internal gas pressure, resulting in poor reproducibility. Furthermore, in studying the microscopic mechanisms and defects of FAPbI3, a slight excess of PbI2 can passivate defects, making it difficult to study the passivation mechanisms of perovskite defects by other materials. In addition, while a slight excess of PbI2 does not significantly affect device efficiency, an excess of FAI leads to a significant decrease in efficiency. Therefore, when both FAI and PbI2 are difficult to control, an excess of PbI2 is often chosen to avoid an excess of FAI. However, an excess of PbI2 will worsen the photostability of the FAPbI3 perovskite film and create vacancies, resulting in significant device hysteresis. Current technologies lack microscopic characterization to elucidate the underlying mechanisms and have not proposed feasible solutions. Since the co-evaporation process directly forms α-FAPbI3 with smaller grains and poorer orientation, it results in more defects and reduced device efficiency; it is also not conducive to electron diffraction of a single crystal.
[0004] Therefore, developing a new method for preparing perovskite thin films to solve the problems of excessive FAI and poor perovskite crystallization during co-evaporation is of great significance to the future development of perovskite. Summary of the Invention
[0005] This invention addresses the technical problems of excessive FAI and poor perovskite crystallization during the co-evaporation process for preparing FAPbI3 perovskite thin films. It proposes a post-processing method for FAPbI3 perovskite thin films, along with the prepared perovskite thin films and their applications. The post-processing method can eliminate excessive FAI in the co-evaporated FAPbI3 perovskite thin films, improve grain morphology, and thus enhance the photoelectric performance of photovoltaic devices.
[0006] The inventive concept of this invention is as follows: During the co-evaporation process of preparing FAPbI3 perovskite thin films, the vapor amounts of FAI and PbI2 cannot be precisely controlled due to the influence of external factors such as temperature and pressure, and excessive FAI has a significant impact on the photoelectric performance of the device. To address this, this invention employs a post-processing method. First, MACl (methylammonium chloride) is introduced in vapor form into the co-evaporated FAPbI3 perovskite thin film with excessive FAI; then, annealing is performed to promote the formation of the mesophases MAPbCl3 and Pb3I8, thereby effectively reducing the phase transition barrier for nucleation and the transformation of the mesophase to the black phase α-FAPbI3, thus promoting the formation of the black phase perovskite. In other words, by forming the mesophase, MACl in this invention not only eliminates excessive FAI but also promotes grain regeneration and improves crystallinity, thereby obtaining a large-grain perovskite thin film and improving the performance of photovoltaic devices.
[0007] To address the aforementioned technical problems, a first aspect of the present invention provides a post-processing method for FAPbI3 perovskite thin films, comprising the following steps: (1) Spray the atomized MACl solution onto the substrate to form a MACl film; (2) Place the FAPbI3 perovskite film above the MACl film, wherein the FAPbI3 perovskite film contains an excess of FAI; then heat the MACl film so that MACl enters the FAPbI3 perovskite film in the form of vapor to form an FAPbI3 perovskite film containing an intermediate phase. (3) The FAPbI3 perovskite film containing the meso phase is annealed to form black phase α-FAPbI3, and the post-treated FAPbI3 perovskite film is obtained.
[0008] In some embodiments of the present invention, in step (1), the atomization method is ultrasonic atomization. By spraying the MACl solution onto the substrate using ultrasonic spraying, the film formation of MACl on the substrate can be precisely controlled by parameters such as height, spraying displacement speed, and spraying air pressure.
[0009] In some embodiments of the present invention, in step (1), the solvent of the MACl solution includes isopropanol, and the concentration of the MACl solution is 0.5-2.5 mg / mL. For example, the concentration of the MACl solution is 0.5 mg / mL, 1.0 mg / mL, 1.5 mg / mL, 2.0 mg / mL, or 2.5 mg / mL; including but not limited to the listed values, and other values not listed are also applicable within the range of values.
[0010] In some embodiments of the present invention, in step (1), the concentration of the MACl solution is 1.0-2.0 mg / mL.
[0011] In some embodiments of the present invention, in step (1), the temperature of the substrate is 75-85°C during the spraying process. Heating the substrate during the spraying process can eliminate the interference of solvent, allowing MCI to be post-treated in the gas phase; and no solvent participates in the reaction throughout the process.
[0012] In some embodiments of the present invention, in step (1), the substrate is soda-lime glass.
[0013] In some embodiments of the present invention, in step (1), the substrate needs to be pretreated before spraying. The pretreatment steps are as follows: first, ultrasonically clean with alcohol for 8-12 minutes, and then clean with plasma for 4-6 minutes to remove impurities from the substrate surface.
[0014] In some embodiments of the present invention, in step (1), the spraying height is 80-92 mm.
[0015] In some embodiments of the present invention, in step (2), the preparation process of the FAPbI3 perovskite film includes the following steps: using FAI and PbI2 as raw materials, the film is prepared by co-evaporation; the evaporation rate ratio of FAI and PbI2 is (1.5-2.5):1.
[0016] In some embodiments of the present invention, the evaporation temperature of PbI2 is 305-315°C, and the evaporation temperature of FAI is 155-165°C.
[0017] In some embodiments of the present invention, the evaporation rate ratio of FAI to PbI2 is (1.75-2.25):1.
[0018] This invention uses a co-evaporation method to prepare FAPbI3 perovskite thin films. This method has no limitation on the size of the conductive substrate and is suitable for the preparation of large-size perovskite thin films.
[0019] In some embodiments of the present invention, in step (2), the FAPbI3 perovskite film is formed on the surface of an FTO glass on which SnO2 is deposited.
[0020] In some embodiments of the present invention, the SnO2 is deposited by a chemical bath deposition method.
[0021] In some embodiments of the present invention, in step (2), the heating temperature is 110-130°C. The fumigation rate of MACl vapor can be controlled by adjusting the temperature of the substrate, thereby controlling the formation rate and uniformity of the mesophase.
[0022] In some embodiments of the present invention, the heating time in step (2) is 8-12 min.
[0023] In some embodiments of the present invention, in step (2), the intermediate phase includes MAPbCl3 and Pb3I8, which are formed by the reaction of MAPbCl into FAPbI3 perovskite. The formation of the intermediate phase improves the quality of the perovskite grains, makes the grains larger, and strengthens the (001) orientation of the perovskite.
[0024] In some embodiments of the present invention, in step (3), the annealing temperature is 140-160°C.
[0025] In some embodiments of the present invention, in step (3), the annealing time is 15-25 minutes. During the annealing process, the intermediate phase disappears, and the black phase α-FAPbI3 is finally formed.
[0026] A second aspect of the present invention provides a FAPbI3 perovskite thin film, prepared using the post-processing method for FAPbI3 perovskite thin films described in the first aspect of the present invention. The FAPbI3 perovskite thin film treated using the post-processing method of the present invention, compared to the untreated film, is free of FAI, has improved crystallinity, and exhibits increased grain size, which is beneficial for improving the photoelectric performance of photovoltaic devices (such as perovskite solar cells).
[0027] A third aspect of the present invention provides a photovoltaic device comprising the FAPbI3 perovskite thin film described in the second aspect of the present invention.
[0028] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages: (1) This invention provides a post-processing method for preparing FAPbI3 perovskite thin films based on co-evaporation. The method first adds MACl in the form of vapor to the perovskite thin film to form an intermediate phase; then performs annealing treatment to eliminate the excess FAI in the FAPbI3 perovskite thin film, promote grain recrystallization, thereby effectively improving the crystal morphology and crystallinity of the co-evaporated perovskite, obtaining a perovskite thin film with large grains, and realizing the improvement of photovoltaic device performance.
[0029] (2) By using MACl to post-process FAPbI3 perovskite films, the present invention can eliminate the influence of excessive FAI on device efficiency, expand the tolerance range of the PbI2 and FAI evaporation rate ratio, and propose a new solution to the unstable organic FAI deposition rate. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of the post-processing technology for FAPbI3 perovskite thin films of the present invention. Figure 2The XRD patterns are of the FAPbI3 perovskite films prepared in Examples 1-3 and Comparative Example 1 of this invention. Figure 3 SEM images of the FAPbI3 perovskite films prepared in Examples 1-3 and Comparative Example 1 of this invention; Figure 4 The image shows the photoelectric performance of solar cells based on FAPbI3 perovskite thin films prepared in Examples 1-3 and Comparative Example 1 of this invention. Figure 5 The image shows the CV curve and external quantum efficiency spectrum of the FAPbI3 perovskite thin film solar cells prepared based on Example 1 and Comparative Example 1 of this invention. Figure 6 Box plots show the efficiency of solar cells based on FAPbI3 perovskite thin films prepared in Example 1 and Comparative Examples 1-5 of this invention. Detailed Implementation
[0031] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.
[0032] Figure 1 This is a schematic diagram of the post-processing technology for FAPbI3 perovskite thin films of the present invention, including the following steps: (1) Using PbI2 and FAI as raw materials, a perovskite film containing a mixed phase of α-FAPbI3 and δ-FAPbI3 is formed by co-evaporation on a substrate coated with SnO2 using a dual-source co-evaporation method.
[0033] (2) Dissolve MACl in IPA to obtain a MACl solution, and then spray it onto soda-lime glass using ultrasonic spraying. During the spraying process, heat the soda-lime glass to evaporate the solvent IPA and form a MACl film.
[0034] (3) Process 1: The perovskite film (PSK) obtained in step (1) is placed on top of the MACl film obtained in step (2), and heated at a low temperature to allow MACl to enter the perovskite film in the form of vapor, forming the mesophases MAPbCl3 and Pb3I8. Process 2: The perovskite film treated in Process 1 is annealed at a high temperature to transform the mesophase into the black phase α-FAPbI3, thus obtaining the post-treated FAPbI3 perovskite film.
[0035] Example 1 A post-processing method for FAPbI3 perovskite thin films includes the following steps: (1) Preparation of SnO2 stock solution: Take 1.096g SnO2·2H2O solid, 5g urea, 5mL concentrated hydrochloric acid, 100μL mercaptoacetic acid and 400mL deionized water into a wide-mouth bottle, shake and mix thoroughly, and store in a 0℃ environment. After 12 hours of aging, it can be used.
[0036] (2) Preparation of SnO2 electron transport layer: The cleaned FTO conductive glass was placed in a UV cleaner and irradiated for 15 min. Then, 20 mL of the SnO2 stock solution obtained in step (1) was taken and 100 mL of deionized water was added to obtain a diluted SnO2 stock solution. After mixing, the solution was placed in an ultrasonic cleaner and ultrasonically treated for 2 min. The UV-cleaned FTO conductive glass was placed face up in a glass box and the diluted SnO2 stock solution was poured in. The glass box was covered with plastic wrap and then the lid was put on and placed in a 90℃ oven for 3 hours. After 3 hours, the surface of the FTO conductive glass was cleaned with deionized water and the glass surface was dried with nitrogen. Finally, the FTO conductive glass was placed on a 180℃ hot plate and kept warm for 60 min. After the glass cooled to room temperature, it was placed in a clean box for storage.
[0037] (3) Weigh 1.2g of PbI2 and 0.65g of FAI. PbI2 and FAI are deposited on the FTO conductive glass substrate containing SnO2 electron transport layer obtained in step (2) at an evaporation rate ratio of 2:1 to form FAPbI3 perovskite film. The substrate rotation speed is 10rpm.
[0038] (4) Take soda-lime glass, first clean it with alcohol by ultrasonic cleaning for 10 min, and then clean it with plasma for 5 min to obtain cleaned soda-lime glass. Dissolve 15 mg of MACl in 10 mL of IPA to prepare a MACl solution with a concentration of 1.5 mg / mL. Spray the solution onto the cleaned soda-lime glass using ultrasonic spraying. During the spraying process, the temperature of the soda-lime glass is 80℃ and the spraying height is 92 mm to form a MACl film.
[0039] (5) Place the FAPbI3 perovskite film obtained in step (3) on top of the MACl film obtained in step (4). First, heat the soda-lime glass substrate to 120°C for 10 minutes to allow MACl to enter the FAPbI3 perovskite film in the form of vapor, forming an FAPbI3 perovskite film containing intermediate phases (MAPbCl3 and Pb3I8). Then, heat the FTO conductive glass substrate to 150°C for 20 minutes to form black phase α-FAPbI3, thus obtaining the post-treated FAPbI3 perovskite film of this embodiment, denoted as MACl-1.5 or MC1.5.
[0040] Example 2 Referring to the preparation method of Example 1, the concentration of MACl solution in step (4) was changed to 0.5 mg / mL to obtain the post-treated FAPbI3 perovskite film of this example, which is denoted as MACl-0.5 or MC0.5.
[0041] Example 3 Following the preparation method of Example 1, only the concentration of the MACl solution in step (4) was changed to 2.5 mg / mL to obtain the post-treated FAPbI3 perovskite film of this example, denoted as MACl-2.5 or MC2.5.
[0042] Example 4 Referring to the preparation method of Example 1, the evaporation rate ratio of PbI2 and FAI in step (3) was changed to 1.75:1 to obtain the post-treated FAPbI3 perovskite film of this example.
[0043] Example 5 Referring to the preparation method of Example 1, the evaporation rate ratio of PbI2 and FAI in step (3) was changed to 2.25:1 to obtain the post-treated FAPbI3 perovskite film of this example.
[0044] Comparative Example 1 A method for preparing FAPbI3 perovskite thin films includes the following steps: (1) Preparation of SnO2 stock solution: Take 1.096g SnO2·2H2O solid, 5g urea, 5mL concentrated hydrochloric acid, 100μL mercaptoacetic acid and 400mL deionized water into a wide-mouth bottle, shake and mix thoroughly, and store in an environment of 0-5℃. After 12 hours of aging, it can be used.
[0045] (2) Preparation of SnO2 electron transport layer: The cleaned FTO conductive glass was placed in a UV cleaner and irradiated for 15 min. Then, 20 mL of the SnO2 stock solution obtained in step (1) was taken and 100 mL of deionized water was added to obtain a diluted SnO2 stock solution. After mixing, the solution was placed in an ultrasonic cleaner and ultrasonically treated for 2 min. The UV-cleaned FTO conductive glass was placed face up in a glass box and the diluted SnO2 stock solution was poured in. The glass box was covered with plastic wrap and then the lid was put on and placed in a 90℃ oven for 3 hours. After 3 hours, the surface of the FTO conductive glass was cleaned with deionized water and the glass surface was dried with nitrogen. Finally, the FTO conductive glass was placed on a 180℃ hot plate and kept warm for 60 min. After the glass cooled to room temperature, it was placed in a clean box for storage.
[0046] (3) Weigh 1.2g of PbI2 and 0.65g of FAI. PbI2 and FAI are deposited on the FTO conductive glass substrate containing SnO2 electron transport layer obtained in step (2) at an evaporation rate ratio of 2:1 to form FAPbI3 perovskite film. The substrate rotation speed is 10rpm, and it is denoted as Ref.
[0047] Comparative Example 2 Referring to the preparation method of Example 1, the amounts of PbI2 and FAI and the evaporation rate in step (3) were changed to obtain the comparative example of a perovskite film with excess FAI, denoted as with MACl-FA 1.15 PbI 3.15 .
[0048] Comparative Example 3 Referring to the preparation method of Example 1, the amounts of PbI2 and FAI and the evaporation rate in step (3) were changed to obtain the PbI-excess perovskite film of this comparative example, denoted as with MACl-FA. 0.85 PbI 2.85 .
[0049] Comparative Example 4 Referring to the preparation method of Comparative Example 1, the amounts of PbI2 and FAI and the evaporation rate in step (3) were changed to obtain the FAI-excess perovskite film of this comparative example, denoted as w / o MACl-FA. 1.15 PbI 3.15 .
[0050] Comparative Example 5 Referring to the preparation method of Example 1, the amounts of PbI2 and FAI and the evaporation rate in step (3) were changed to obtain the PbI-excess perovskite film of this comparative example, denoted as w / o MACl-FA. 0.85 PbI 2.85 .
[0051] Comparative Example 6 A method for preparing FAPbI3 perovskite thin films includes the following steps: (1) Preparation of SnO2 stock solution: Take 1.096g SnO2·2H2O solid, 5g urea, 5mL concentrated hydrochloric acid, 100μL mercaptoacetic acid and 400mL deionized water into a wide-mouth bottle, shake and mix thoroughly, and store in an environment of 0-5℃. After 12 hours of aging, it can be used.
[0052] (2) Preparation of SnO2 electron transport layer: The cleaned FTO conductive glass was placed in a UV cleaner and irradiated for 15 min. Then, 20 mL of the SnO2 stock solution obtained in step (1) was taken and 100 mL of deionized water was added to obtain a diluted SnO2 stock solution. After mixing, the solution was placed in an ultrasonic cleaner and ultrasonically treated for 2 min. The UV-cleaned FTO conductive glass was placed face up in a glass box and the diluted SnO2 stock solution was poured in. The glass box was covered with plastic wrap and then the lid was put on and placed in a 90℃ oven for 3 hours. After 3 hours, the surface of the FTO conductive glass was cleaned with deionized water and the glass surface was dried with nitrogen. Finally, the FTO conductive glass was placed on a 180℃ hot plate and kept warm for 60 min. After the glass cooled to room temperature, it was placed in a clean box for storage.
[0053] (3) 11.54 g of MACl, 77.38 g of FAI, and 228.19 g of PbI2 were mixed to obtain perovskite powder. Then, the perovskite powder was added to a 320 μL DMF:DMSO = 8:1 mixed solution to prepare a perovskite precursor solution. Subsequently, FAPbI3 perovskite film was spin-coated onto the FTO conductive glass substrate containing the SnO2 electron transport layer obtained in step (2). The spin-coating process was as follows: spin-coating at 1000 rpm for 10 s, and then spin-coating at 5000 rpm for 30 s. 100-200 μL of ethyl acetate was added dropwise in the last 10-20 s of the second stage. Immediately afterwards, the perovskite liquid film was annealed on a hot plate at 150 °C for 15 min to obtain the FAPbI3 perovskite film of this comparative example, denoted as MACl-1.5-1.
[0054] Application examples Perovskite solar cells were fabricated using the post-treated FAPbI3 perovskite films prepared in Examples 1-5 and Comparative Examples 1-6, respectively, following the specific steps: 1) Preparation of the hole transport layer: Weigh 500 mg of Li-TFSI using a balance, dissolve it in 1 mL of acetonitrile, and mix thoroughly to prepare the lithium salt solution. Weigh 520 mg of FK209, dissolve it in 1 mL of acetonitrile, and mix thoroughly to prepare the cobalt salt solution. Weigh 73 mg of Spiro-OMeTAD powder, dissolve it in 1 mL of chlorobenzene, and add 18 μL of lithium salt, 29 μL of cobalt salt, and 30 μL of tBP to the solution. Place the prepared Spiro-OMeTAD solution on a shaker and shake for 30 minutes.
[0055] 2) Take the FAPbI3 perovskite film prepared above onto a spin coater, and use a pipette to take 20 μL of the Spiro-OMeTAD solution prepared in step 1) and spread it evenly on the surface of the FAPbI3 perovskite film. The spin coating parameters are a spin speed of 3000 rpm and a spin coating time of 30 seconds.
[0056] 3) Preparation of metal electrodes: After loading the sample prepared in step 2) into a mask plate, place it into a vacuum evaporator. After evaporating the chamber to 1×10-6 torr, evaporate the 80nm gold electrode at an evaporation rate of 0.5-1.5 Å / s to obtain a perovskite solar cell.
[0057] Performance testing 1. Structural Characterization Figure 2 Parts a and b in the figure are the XRD patterns and full width at half maximum (FWHM) plots of the FAPbI3 perovskite films prepared in Examples 1-3 and Comparative Example 1, respectively. The horizontal axis 2-Theta represents the diffraction angle 2θ, and the vertical axis Intensity represents the intensity of the diffraction peak. Figure 2 It can be seen that with the increase of MACl concentration, the preferred orientation of the (001) crystal plane of the perovskite film is enhanced, and PbI2 diffraction peaks appear, with the full width at half maximum (FWHM) of the diffraction peaks gradually decreasing. The appearance of the PbI2 diffraction peaks indicates that there is no excess FAI in the film.
[0058] Figure 3 The images show SEM images of the FAPbI3 perovskite films prepared in Examples 1-3 and Comparative Examples 1 and 6. It can be seen that the perovskite grain size gradually increases with increasing MACl concentration, indicating that appropriate MACl treatment can significantly improve the film crystallinity quality. It should be noted that when MACl is excessive, more pores appear in the film. Even in Comparative Example 6, where MACl was added as an additive to the perovskite precursor, a small number of pores were still present in the film.
[0059] 2. Photoelectric properties The light intensity for the following photoelectric performance tests is based on one sun (AM1.5G, 100mW / cm²). 2 (It is calibrated using standard silicon cells).
[0060] Figure 4 The "ad" part represents the power conversion efficiency (PCE), open-circuit voltage, current density, and fill factor of perovskite solar cells based on FAPbI3 perovskite films post-treated with different concentrations of MACl from Examples 1-3 and Comparative Example 1. Figure 4 It can be seen that the device performance is optimal when the MACl concentration is 1.5 mg / mL, mainly due to the improved current density and fill factor. However, excessive MACl will lead to a decrease in open-circuit voltage, thereby reducing the overall device efficiency.
[0061] Figure 5 Parts a and b in the figure represent the reverse (R) and forward (F) scan CV curves and external quantum efficiency (EQE) spectra of solar cells based on FAPbI3 perovskite thin films prepared in Example 1 and Comparative Example 1, respectively. Figure 5 It can be seen that after MACl processing, the device efficiency is improved, the hysteresis effect in the current-voltage test is reduced, the integral current is increased, and the optical bandgap does not change significantly.
[0062] Figure 6 Box plots show the efficiency of solar cells based on FAPbI3 perovskite thin films prepared in Examples 1 and Comparative Examples 1-5, comparing the efficiency performance of devices under conditions of excessive FAI, excessive PbI2, and conventional stoichiometry. The results show that the device efficiency decreases most significantly under excessive FAI conditions. However, after MACl treatment, even with excessive FAI, the device efficiency can still recover to nearly 16%, indicating that appropriate MACl treatment can broaden the process window for FAI evaporation rate in the co-evaporation process and reduce the efficiency loss caused by slight FAI excess.
[0063] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.
Claims
1. A post-processing method for FAPbI3 perovskite thin films, characterized in that, Includes the following steps: (1) Spray the atomized MACl solution onto the substrate to form a MACl film; (2) Place the FAPbI3 perovskite film above the MACl film, wherein the FAPbI3 perovskite film contains an excess of FAI; then heat the MACl film so that MACl enters the FAPbI3 perovskite film in the form of vapor to form an FAPbI3 perovskite film containing an intermediate phase. (3) The FAPbI3 perovskite film containing the meso phase is annealed to form black phase α-FAPbI3, and the post-treated FAPbI3 perovskite film is obtained.
2. The post-processing method for FAPbI3 perovskite thin films according to claim 1, characterized in that, In step (1), the solvent of the MACl solution includes isopropanol, and the concentration of the MACl solution is 0.5-2.5 mg / mL.
3. The post-processing method for FAPbI3 perovskite thin films according to claim 1, characterized in that, In step (1), the temperature of the substrate is 75-85℃.
4. The post-processing method for FAPbI3 perovskite thin films according to claim 1, characterized in that, In step (1), the substrate is soda-lime glass.
5. The post-processing method for FAPbI3 perovskite thin films according to claim 1, characterized in that, In step (2), the preparation process of the FAPbI3 perovskite film includes the following steps: using FAI and PbI2 as raw materials, it is prepared by co-evaporation; the evaporation rate ratio of FAI and PbI2 is (1.5-2.5):
1.
6. The post-processing method for FAPbI3 perovskite thin films according to claim 1, characterized in that, In step (2), the heating temperature is 110-130℃; and / or the heating time is 8-12 min.
7. The post-processing method for FAPbI3 perovskite thin films according to claim 1, characterized in that, In step (2), the intermediate phase includes MAPbCl3 and Pb3I8.
8. The post-processing method for FAPbI3 perovskite thin films according to claim 1, characterized in that, In step (3), the annealing temperature is 140-160℃; and / or the annealing time is 15-25min.
9. A FAPbI3 perovskite thin film, characterized in that, The FAPbI3 perovskite thin film was prepared using the post-processing method described in any one of claims 1-8.
10. A photovoltaic device, characterized in that, Including the FAPbI3 perovskite thin film as described in claim 9.