Perovskite thin film and preparation method thereof, perovskite solar cell module and preparation process thereof

Abstract

This invention provides a perovskite thin film and its preparation method, a perovskite solar cell module and its preparation process. The preparation method includes: (1) purging the slurry layer formed after coating the perovskite precursor slurry to obtain a wet film in a pre-crystallized state that is both non-flowing and permeable; (2) vacuum drying and crystallizing the obtained wet film in a pre-crystallized state that is both non-flowing and permeable to obtain a perovskite precursor layer; (3) heat-treating the obtained perovskite precursor layer to obtain a perovskite thin film. The preparation method, by introducing a purging step beforehand, forms a pre-crystallized structure on the surface of the slurry layer that is both non-flowing and permeable, overcoming defects such as blistering and pinholes caused by direct vacuum drying and crystallization, and optimizing the solvent evaporation process, thus shortening the vacuum drying time. The preparation method has high preparation efficiency, and the prepared perovskite thin film has high quality, good uniformity, and improved thickness.

Description

Technical Field

[0001] This invention belongs to the field of perovskite battery technology, and relates to a method for preparing a perovskite thin film, particularly a perovskite thin film and its preparation method, a perovskite solar cell module and its preparation process. Background Technology

[0002] Currently, the fabrication of large-area perovskite photovoltaic modules mainly follows the mainstream process route of "solution coating - solvent removal / nucleation - annealing and crystallization". In this process, the precursor solution is usually coated, blade-coated or sprayed in air or an inert atmosphere. Then, the wet film, which still contains a high concentration of solvent, is transferred to a vacuum drying device (VCD). After removing the solvent by depressurization, it undergoes thermal annealing treatment, and finally the precursor is converted into a perovskite thin film.

[0003] However, the aforementioned conventional process has significant limitations: First, when the wet film enters the VCD directly, the solvent vaporizes instantaneously under low pressure, easily causing blistering, pore formation, or localized peeling on the film surface, making it difficult to prepare high-quality perovskite films. Second, nucleation is mainly controlled by the local pressure and temperature field within the VCD cavity, making it difficult to obtain a consistent nucleation starting point across the entire film, resulting in difficulty in preparing perovskite films with high uniformity, thus making it difficult to ensure the uniformity of large-area perovskite photovoltaic modules. Third, a large amount of solvent is carried into the VCD cavity, increasing the pumping load of the vacuum system, requiring higher vacuum levels and longer residence times, affecting the production line cycle time, and thus resulting in lower perovskite film preparation efficiency. Finally, the high fluidity of the wet film makes it difficult to prepare films with greater thickness, limiting module efficiency.

[0004] For example, CN117979785A discloses a method for preparing a perovskite film and a perovskite solar cell. The method may include: coating a perovskite precursor solution onto a flexible substrate, and pre-evaporating the perovskite precursor solution coated on the flexible substrate to form a perovskite intermediate; covering the flexible substrate onto a textured substrate, wherein the perovskite intermediate is located between the flexible substrate and the substrate; uniformly applying pressure to the flexible substrate through a gaseous or liquid medium, causing the flexible substrate and the perovskite intermediate to deform according to the textured structure; and vacuum drying the perovskite intermediate deformed according to the textured structure to form a perovskite film matching the textured structure, wherein the perovskite film is adhered to the substrate.

[0005] For example, CN109545977A discloses a method for preparing a textured, uniform perovskite film by liquid film thickening and anti-crystallization in situ, comprising: first, preparing a perovskite precursor sol or solution containing a thickener; second, uniformly coating the perovskite liquid film; third, drying the perovskite liquid film; fourth, solvent removal heat treatment of the perovskite film: annealing the dried perovskite film at 90~150℃ for 10~120min to remove residual solvent; fifth, thickener removal heat treatment of the perovskite film: annealing the perovskite film treated in step fourth at 100~180℃ for 10~120min to remove the thickener and promote grain growth, finally obtaining a pyramid-shaped textured, uniform perovskite film.

[0006] In summary, the existing methods for preparing perovskite thin films all have certain drawbacks, including low preparation efficiency, poor quality and uniformity of the resulting perovskite thin films, and limited thickness. Therefore, it is crucial to develop and design a novel perovskite thin film and its preparation method, as well as a perovskite solar cell module and its fabrication process. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a perovskite thin film and its preparation method, as well as a perovskite solar cell module and its preparation process. The preparation method provided by the present invention introduces a purging step after coating and before vacuum drying and crystallization, so that the surface of the slurry layer forms a pre-crystallized structure that is both non-flowing and permeable. This effectively overcomes the defects such as blistering and pinholes caused by direct vacuum drying, optimizes the solvent evaporation process, and significantly shortens the vacuum drying time. Therefore, the preparation method has high preparation efficiency, and the prepared perovskite thin film has high quality, excellent uniformity, and improved thickness.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a perovskite thin film, the method comprising:

[0010] (1) The slurry layer formed after the perovskite precursor slurry is coated is purged so that some of the solvent evaporates and a continuous pre-crystallized structure is formed in the surface of the slurry layer, so as to obtain a wet film in a pre-crystallized state that is neither flowing nor permeable.

[0011] (2) The pre-crystallized wet film obtained in step (1) is subjected to vacuum drying and crystallization to obtain a perovskite precursor layer.

[0012] (3) Heat-treat (annealing and phase fixation) the perovskite precursor layer obtained in step (2) to obtain a perovskite thin film.

[0013] In the preparation method provided by the present invention, in step (1), purging is performed immediately after coating. The purging is used to quickly remove some of the highly volatile solvent from the surface of the slurry layer, induce the surface of the slurry layer to form a continuous pre-crystallized structure (the surface changes from a fluid state to a semi-solid state), and adjust the slurry layer from a state of high solvent and easy flow to a state with certain mechanical support and nucleation points, thereby forming a wet film in a pre-crystallized state that is neither flowable nor permeable. This avoids the bubbling, pinholes and stripe defects caused by instantaneous vaporization of solvent when the slurry layer is directly vacuum dried and crystallized in step (2), thereby improving the quality of the perovskite film.

[0014] In the preparation method provided by the present invention, the purging in step (1) can be carried out at atmospheric pressure, which can complete the densification and nucleation of the slurry layer surface without increasing the burden on the vacuum system, ensuring that the initial wet film in step (2) is in a uniform initial crystallization stage, thereby significantly improving the uniformity of the perovskite film. The perovskite film prepared has uniform grains and no obvious pinholes, thereby improving the uniformity of the perovskite solar cell module.

[0015] In the preparation method provided by the present invention, since a large amount of highly volatile solvent has been removed during the purging in step (1), the vacuum degree and halide vapor partial pressure in the vacuum drying equipment are more likely to remain stable during vacuum drying and crystallization in step (2), thereby shortening the vacuum drying and crystallization time or reducing the vacuum degree requirement, thus shortening the preparation time and improving the production capacity of the production line.

[0016] In the preparation method provided by the present invention, the heat treatment in step (3) is used to eliminate the residual internal stress generated in the slurry layer during the pre-crystallization and vacuum drying crystallization process, promote the growth of perovskite grains, crystal rearrangement and crystal phase densification, and stabilize the perovskite phase structure, thereby obtaining a dense perovskite film with good light activity, and improving the open circuit voltage, fill factor and stability of the perovskite solar cell module.

[0017] The preparation method provided by this invention has good compatibility with existing air coating production lines. It only requires adding a purging process after the existing coating process and connecting it normally with the existing sequential vacuum drying, crystallization and heat treatment processes to complete the modification. It is suitable for component-level, roll-to-roll and large-area production.

[0018] In summary, the preparation method provided by this invention introduces a purging step after coating and before vacuum drying and crystallization, which forms a pre-crystallized structure on the surface of the slurry layer that is both non-flowing and permeable. This effectively overcomes defects such as blistering and pinholes caused by direct vacuum drying, optimizes the solvent evaporation process, and significantly shortens the vacuum drying time. Therefore, the preparation method has high efficiency, and the prepared titanium dioxide film has high quality, excellent uniformity, and improved thickness.

[0019] Preferably, the chemical formula of the solute in the perovskite precursor slurry in step (1) is ABX3; wherein, A includes any one or a combination of at least two of cesium ions, rubidium ions, methylamine ions, formamidinium ions, or guanidine ions; B includes any one or a combination of at least two of lead ions, tin ions, or germanium ions; and X includes any one or a combination of at least two of iodide ions, bromide ions, or chloride ions, preferably Cs. 0.05 FA 0.95 PbI3.

[0020] In this invention, A includes any one or a combination of at least two of cesium ions, rubidium ions, methylamine ions, formamidinium ions, or guanidine ions. Typical but non-limiting combinations include combinations of cesium ions and rubidium ions, combinations of methylamine ions and formamidinium ions, combinations of guanidine ions and methylamine ions, or combinations of cesium ions, formamidinium ions, and guanidine ions.

[0021] In this invention, B includes any one or a combination of at least two of lead ions, tin ions, or germanium ions. Typical but non-limiting combinations include combinations of lead ions and tin ions, combinations of tin ions and germanium ions, or combinations of lead ions, tin ions, and germanium ions.

[0022] In this invention, X includes any one or a combination of at least two of iodide ions, bromide ions, or chloride ions. Typical but non-limiting combinations include combinations of iodide ions and bromide ions, combinations of bromide ions and chloride ions, or combinations of iodide ions, bromide ions, and chloride ions.

[0023] Preferably, the concentration of solute in the perovskite precursor slurry in step (1) is 0.6 mol / L to 1.0 mol / L, for example, it can be 0.60 mol / L, 0.65 mol / L, 0.70 mol / L, 0.75 mol / L, 0.80 mol / L, 0.85 mol / L, 0.90 mol / L, 0.95 mol / L or 1.00 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the solvent in the perovskite precursor slurry in step (1) includes any one or a combination of at least two of (dimethyl sulfoxide) DMSO, (N,N-dimethylformamide) DMF, or 2-methoxyethanol (2-ME). Typical but non-limiting combinations include combinations of DMSO and DMF, DMF and 2-ME, DMSO and 2-ME, or combinations of DMSO, DMF, and 2-ME.

[0025] Preferably, the coating in step (1) includes: coating the perovskite precursor slurry in an air atmosphere to obtain a slurry layer.

[0026] Preferably, the coating method in step (1) includes slot coating.

[0027] Preferably, in step (1), after the slurry layer formed by coating the perovskite precursor slurry is formed, it enters the purging zone at a conveying speed of 0.5 m / min to 2 m / min. For example, it can be 0.5 m / min, 0.7 m / min, 0.9 m / min, 1.1 m / min, 1.3 m / min, 1.5 m / min, 1.7 m / min, 1.9 m / min or 2.0 m / min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] Preferably, the airflow velocity during purging in step (1) is 5m / s to 30m / s, the airflow temperature is 20℃ to 40℃, the tangential angle or downward blowing angle of the airflow direction relative to the surface of the slurry layer is 45° to 70°, and the purging time is 1s to 5s.

[0029] In this invention, the airflow velocity during the purging process in step (1) is 5m / s to 30m / s, for example, it can be 5m / s, 8m / s, 10m / s, 12m / s, 15m / s, 18m / s, 20m / s, 22m / s, 25m / s, 28m / s or 30m / s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] In this invention, the airflow temperature in step (1) is 20℃~40℃, for example, it can be 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃ or 40℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] In this invention, the tangential angle or down-blowing angle of the airflow direction relative to the surface of the slurry layer in step (1) is 45°~70°, for example, it can be 45°, 48°, 50°, 52°, 55°, 58°, 60°, 62°, 65°, 68° or 70°, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] In this invention, the tangential angle between the airflow direction and the surface of the slurry layer refers to the angle between the airflow direction and the tangent of the slurry layer surface, which is parallel or approximately parallel. This allows the airflow to pass evenly along the film surface, reducing the impact damage to the wet film, while efficiently removing the highly volatile solvents from the surface of the slurry layer and promoting the formation of a continuous pre-crystallized structure.

[0033] In this invention, the downward blowing angle of the airflow direction relative to the surface of the slurry layer refers to the angle formed by the airflow direction pointing obliquely downward from the air knife to the surface of the slurry layer. This enhances the targeting of solvent removal, directing the action on the surface of the slurry layer. While avoiding flow on the slurry layer film surface, it precisely controls the amount of residual solvent to the target range.

[0034] In this invention, the purging time in step (1) is 1s to 5s, for example, it can be 1.0s, 1.5s, 2.0s, 2.5s, 3.0s, 3.5s, 4.0s, 4.5s or 5.0s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the purging in step (1) is performed using at least one narrow-slit air knife, wherein the width of the air knife slit is 0.5mm to 1.0mm and the distance between the air knife and the surface of the slurry layer is 20mm to 40mm;

[0036] During the purging process described in step (1), the resulting slurry layer is purged using dry nitrogen, dry air, or nitrogen mixed with low-boiling-point solvent vapor (to adjust the nucleation density and desolventization rate).

[0037] In this invention, the slit width of the narrow-slit air knife is 0.5mm to 1.0mm, for example, it can be 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm or 1.0mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] In this invention, the distance between the air knife of the narrow-slit air knife and the surface of the slurry layer is 20mm to 40mm, for example, it can be 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm, 34mm, 36mm, 38mm or 40mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the narrow-slit air knife in step (1) is located downstream of the coating apparatus for coating perovskite precursor slurry.

[0040] Preferably, in the purging process described in step (1), at least one narrow-slit air knife forms a combination structure including top and bottom blowing or a combination structure of top blowing and bottom suction with a negative pressure suction component (to adapt to the requirements of different perovskite films).

[0041] In this invention, the upper and lower opposing airflow refers to the arrangement of at least one narrow-slit air knife above and below the membrane surface, with the air outlets of the two air knives at symmetrical or complementary angles relative to the membrane surface, forming a combined structure in which the airflow "blows in opposite directions" towards the membrane surface.

[0042] In this invention, the "upward blowing and downward suction" refers to a combination structure in which a narrow slit-type air knife (blowing) is set above the membrane surface and a negative pressure suction component (suction) is set below the membrane surface, and the airflow is in the pattern of "blowing above and suction below".

[0043] Preferably, the dry nitrogen gas is nitrogen gas with a dew point temperature of -40℃ to -60℃. The dew point temperature of the nitrogen gas can be, for example, -40℃, -42℃, -44℃, -46℃, -48℃, -50℃, -52℃, -54℃, -56℃, -58℃ or -60℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the volume fraction of the low-boiling-point solvent vapor incorporated into the nitrogen gas is 1 vol% to 10 vol%, for example, it can be 1 vol%, 2 vol%, 3 vol%, 4 vol%, 5 vol%, 6 vol%, 7 vol%, 8 vol%, 9 vol%, or 10 vol%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, in the pre-crystallized wet film in step (1) which is neither flowing nor permeable, the mass of residual solvent is 20% to 50% of the mass of the perovskite film obtained in step (3). For example, it can be 20%, 25%, 30%, 35%, 40%, 45%, or 50%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Preferably, the vacuum drying crystallization in step (2) is carried out under a pressure of 5 Pa to 50 Pa, a temperature of 20°C to 35°C, and a time of 30 s to 70 s.

[0047] In this invention, the vacuum drying crystallization in step (2) is carried out under a pressure of 5 Pa to 50 Pa, for example, it can be 5 Pa, 10 Pa, 15 Pa, 20 Pa, 25 Pa, 30 Pa, 35 Pa, 40 Pa, 45 Pa or 50 Pa, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] In this invention, the temperature of vacuum drying crystallization in step (2) is 20℃~35℃, for example, it can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃ or 35℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] In this invention, the vacuum drying and crystallization time in step (2) is 30s to 70s, for example, it can be 30s, 35s, 40s, 45s, 50s, 55s, 60s, 65s or 70s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Preferably, the vacuum drying crystallization in step (2) is carried out in a vacuum drying apparatus.

[0051] Preferably, the vacuum drying apparatus includes a vacuum drying device (VCD).

[0052] Preferably, the time for conveying the pre-crystallized wet film obtained in step (1), which is neither flowing nor permeable, to the vacuum drying device shall not exceed 5s, for example, it may be 1.0s, 1.5s, 2.0s, 2.5s, 3.0s, 3.5s, 4.0s, 4.5s or 5.0s, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0053] Preferably, during the vacuum drying and crystallization process in step (2), halide vapor is also introduced for gas-phase conversion. The halide vapor includes any one or at least two combinations of FAI vapor, MAI vapor, CsI vapor or MABr vapor. Typical but non-limiting combinations include the combination of FAI vapor and MAI vapor, the combination of CsI vapor and MABr vapor, the combination of MAI vapor and MABr vapor, or the combination of FAI vapor, MAI vapor and CsI vapor. Wherein, FA is formamidinium ion, MA is methylamine ion, and Cs is cesium ion.

[0054] In this invention, during the vacuum drying and crystallization process described in step (2), halide vapor is also introduced for gas-phase conversion. The specific type and ratio of the introduced halide vapor can be adjusted according to the target perovskite system. This treatment aims to utilize the halide vapor to react with the pre-crystallized wet film, which is neither flowing nor permeable, to promote the formation of the perovskite precursor layer, while simultaneously achieving halide replenishment and grain growth, thereby reducing film surface defects and enhancing the uniformity of the perovskite photovoltaic film.

[0055] Preferably, in the vacuum drying and crystallization process described in step (2), the method of introducing halide vapor includes: introducing halide vapor into the vacuum drying equipment (VCD).

[0056] Preferably, the heat treatment in step (3) is performed at a temperature of 80°C to 180°C for a time of 5 min to 15 min, and in an air atmosphere.

[0057] In this invention, the heat treatment temperature in step (3) is 80℃~180℃, for example, it can be 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃ or 180℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] In this invention, the heat treatment time in step (3) is 5 min to 15 min, for example, it can be 5.0 min, 6.0 min, 7.0 min, 8.0 min, 9.0 min, 10.0 min, 11.0 min, 12.0 min, 13.0 min, 14.0 min or 15.0 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] Preferably, in the preparation method, the coating, purging, vacuum drying crystallization and heat treatment are arranged in sequence on the same continuous production line.

[0060] In this invention, when the coating, airflow velocity, vacuum drying and crystallization, and heat treatment are arranged in sequence on the same continuous production line, the matching between the wet film state and the conditions of vacuum drying and crystallization and the final heat treatment is ensured by controlling the linear speed of the continuous production line, the airflow velocity during purging, and the temperature and pressure during vacuum drying and crystallization, thereby preparing a perovskite thin film with excellent performance.

[0061] In a second aspect, the present invention provides a perovskite thin film, which is obtained by the preparation method described in the first aspect.

[0062] Preferably, the thickness of the perovskite film is 550nm to 750nm, for example, it can be 550nm, 580nm, 600nm, 620nm, 650nm, 680nm, 700nm, 720nm or 750nm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0063] Thirdly, the present invention provides a fabrication process for a perovskite solar cell module, the fabrication process comprising:

[0064] When preparing perovskite thin films for large-area perovskite photovoltaic modules, the preparation method described in the first aspect is used.

[0065] Fourthly, the present invention provides a perovskite solar cell module, wherein the perovskite solar cell module is obtained by the fabrication process described in the third aspect.

[0066] In this invention, the size of the perovskite solar cell module is 10cm~120cm×10cm~200cm, for example, it can be 10cm×10cm, 30cm×40cm, 30cm×50cm, 50cm×70cm, 70cm×90cm, 90cm×110cm, 110cm×130cm, 120cm×150cm or 120cm×200cm, but it is not limited to the listed sizes. Other unlisted size combinations within this size range are also applicable.

[0067] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] (1) In the preparation method provided by the present invention, in step (1), purging is performed immediately after coating. The purging is used to quickly remove some of the highly volatile solvent from the surface of the slurry layer, induce the surface of the slurry layer to form a continuous pre-crystallized structure (the surface changes from a fluid state to a semi-solid state), and adjust the slurry layer from a state of high solvent and easy flow to a state with a certain mechanical support and nucleation points, thereby forming a wet film in a pre-crystallized state that is neither flowable nor permeable. This avoids the bubbling, pinhole and stripe defects caused by instantaneous vaporization of solvent when the slurry layer is directly vacuum dried and crystallized in step (2), thereby improving the quality of the perovskite film.

[0070] (2) In the preparation method provided by the present invention, the purging in step (1) can be carried out at the atmospheric pressure end, which can complete the densification and nucleation of the slurry layer surface without increasing the burden on the vacuum system, ensuring that the initial wet film in step (2) is in a uniform initial crystallization stage, thereby significantly improving the uniformity of the perovskite film. The perovskite film prepared has uniform grains and no obvious pinholes, thereby improving the uniformity of the perovskite solar cell module.

[0071] (3) In the preparation method provided by the present invention, since a large amount of highly volatile solvent has been removed during the purging in step (1), the vacuum degree and halide vapor partial pressure in the vacuum drying equipment are more likely to remain stable during vacuum drying and crystallization in step (2), thereby shortening the time of vacuum drying and crystallization or reducing the vacuum degree requirement, thereby shortening the time of the preparation method and improving the production capacity of the production line.

[0072] (4) In the preparation method provided by the present invention, the heat treatment in step (3) is used to eliminate the residual internal stress generated in the slurry layer during the pre-crystallization and vacuum drying crystallization process, promote the growth of perovskite grains, crystal rearrangement and crystal phase densification, and stabilize the perovskite phase structure, thereby obtaining a dense perovskite film with good light activity, and improving the open circuit voltage, fill factor and stability of the perovskite solar cell module.

[0073] (5) The preparation method provided by the present invention has good compatibility with existing air coating production lines. Only a purging process needs to be added after the existing coating, and the existing vacuum drying crystallization and heat treatment processes can be connected normally to complete the transformation. It is suitable for component-level, roll-to-roll and large-area production.

[0074] (6) The preparation method provided by the present invention introduces a purging step after coating and before vacuum drying and crystallization, so that the surface of the slurry layer forms a pre-crystallized structure that is neither flowing nor permeable, which effectively overcomes the defects such as bubbling and pinholes caused by direct vacuum drying, optimizes the solvent evaporation process, and significantly shortens the vacuum drying time; therefore, the preparation method has high preparation efficiency, and the titanium dioxide film prepared has high quality, better uniformity, and improved thickness. Attached Figure Description

[0075] Figure 1 The XRD patterns are of the perovskite films obtained by the preparation methods provided in Example 2 and Comparative Example 1.

[0076] Figure 2 The current-voltage characteristic curves of the perovskite solar cell modules obtained by the fabrication process provided in Application Example 2 and Comparative Application Example 1 are shown. Detailed Implementation

[0077] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0078] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0079] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0080] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0081] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0082] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0083] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0084] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0085] Example 1

[0086] This embodiment provides a method for preparing a perovskite thin film, the method comprising:

[0087] (1) In an air atmosphere, after the perovskite precursor slurry is slit coated to obtain a slurry layer, it is transported into the purging area at a conveying speed of 1 m / min; the obtained slurry layer is purged, so that some solvent evaporates and a continuous pre-crystallized structure is formed in the surface of the slurry layer, and a wet film in a pre-crystallized state that is neither flowing nor permeable is obtained (the mass of residual solvent is 35% of the mass of the perovskite film obtained in (3)).

[0088] The concentration of the solute in the perovskite precursor slurry is 0.8 mol / L, and the solute is Cs. 0.05 FA 0.95 PbI3, with dimethyl sulfoxide (DMSO) as the solvent;

[0089] The airflow velocity during purging is 15 m / s, the airflow temperature is 30°C, the tangential angle between the airflow direction and the surface of the slurry layer is 55°, and the purging time is 1 second.

[0090] The purging is performed using two narrow-slit air knives located downstream of the coating device used for coating the perovskite precursor slurry. The two narrow-slit air knives form an up-and-down opposing air-blowing structure. The width of the air knife slit is 0.8 mm, and the distance between the air knife and the surface of the slurry layer is 30 mm.

[0091] During the purging process, dry nitrogen (nitrogen with a dew point temperature of -5°C) is used to purge the resulting slurry layer.

[0092] (2) The pre-crystallized wet film obtained in step (1) is neither flowing nor permeable and is transported to the vacuum drying chamber of the vacuum drying device within 2s. The pre-crystallized wet film obtained in step (1) is subjected to vacuum drying and crystallization for 50s in the vacuum drying chamber with a pressure of 10Pa and a temperature of 25℃ to obtain the perovskite precursor layer.

[0093] During the vacuum drying and crystallization process, FAI vapor is also introduced into the vacuum drying chamber of the vacuum drying device to carry out gas-phase conversion;

[0094] (3) In an air atmosphere, the perovskite precursor layer obtained in step (2) is subjected to heat treatment (annealing and phase fixation) at 130°C for 10 minutes to obtain a perovskite thin film.

[0095] Example 2

[0096] This embodiment provides a method for preparing a perovskite thin film, the method comprising:

[0097] (1) In an air atmosphere, after the perovskite precursor slurry is slit coated to obtain a slurry layer, it is transported into the purging area at a conveying speed of 0.5 m / min; the obtained slurry layer is purged, so that some solvent evaporates and a continuous pre-crystallized structure is formed in the surface of the slurry layer, and a wet film in a pre-crystallized state that is neither flowing nor permeable is obtained (the mass of residual solvent is 50% of the mass of the perovskite film obtained in (3)).

[0098] The concentration of the solute in the perovskite precursor slurry is 0.6 mol / L, and the solute is Cs. 0.05 FA 0.95PbI3, with N,N-dimethylformamide (DMF) as the solvent;

[0099] The airflow velocity during purging is 5 m / s, the airflow temperature is 40°C, the tangential angle or downward blowing angle of the airflow direction relative to the surface of the slurry layer is 45°, and the purging time is 1 second.

[0100] The purging is performed using a narrow-slit air knife located downstream of the coating device used for coating the perovskite precursor slurry. The narrow-slit air knife and the negative pressure suction assembly form an upward blowing and downward suction combination structure. The width of the air knife slit is 1.0 mm, and the distance between the air knife and the surface of the slurry layer is 20 mm.

[0101] During the purging process, dry nitrogen (nitrogen with a dew point temperature of -40°C) is used to purge the resulting slurry layer.

[0102] (2) The pre-crystallized wet film obtained in step (1) that is neither flowing nor permeable is transported to the vacuum drying chamber of the vacuum drying device within 5s. The pre-crystallized wet film obtained in step (1) that is neither flowing nor permeable is subjected to vacuum drying and crystallization for 70s in the vacuum drying chamber with a pressure of 5Pa and a temperature of 20℃ to obtain the perovskite precursor layer.

[0103] During the vacuum drying and crystallization process, FAI vapor is also introduced into the vacuum drying chamber of the vacuum drying device to carry out gas-phase conversion;

[0104] (3) In an air atmosphere, the perovskite precursor layer obtained in step (2) is subjected to heat treatment (annealing and phase fixation) at 180°C for 5 minutes to obtain a perovskite film.

[0105] Example 3

[0106] This embodiment provides a method for preparing a perovskite thin film, the method comprising:

[0107] (1) In an air atmosphere, after the perovskite precursor slurry is slit coated to obtain a slurry layer, it is transported into the purging area at a conveying speed of 2 m / min; the obtained slurry layer is purged, so that some solvent evaporates and a continuous pre-crystallized structure is formed in the surface of the slurry layer, and a wet film in a pre-crystallized state that is neither flowing nor permeable is obtained (the mass of residual solvent is 20% of the mass of the perovskite film obtained in (3)).

[0108] The concentration of the solute in the perovskite precursor slurry is 1.0 mol / L, and the solute is Cs. 0.05 FA 0.95 PbI3, with 2-methoxyethanol (2-ME) as the solvent;

[0109] The airflow velocity during purging is 30 m / s, the airflow temperature is 20°C, the tangential angle or downward blowing angle of the airflow direction relative to the surface of the slurry layer is 70°, and the purging time is 5 s.

[0110] The purging is performed using two narrow-slit air knives located downstream of the coating device used for coating the perovskite precursor slurry. The two narrow-slit air knives form a combined structure including top and bottom counter-blowing. The width of the air knife slit is 0.5 mm, and the distance between the air knife and the surface of the slurry layer is 40 mm.

[0111] During the purging process, dry nitrogen (nitrogen with a dew point temperature of -60°C) is used to purge the resulting slurry layer.

[0112] (2) The pre-crystallized wet film obtained in step (1) is neither flowing nor permeable and is transported to the vacuum drying chamber of the vacuum drying device within no more than 3 seconds. The pre-crystallized wet film obtained in step (1) is subjected to vacuum drying and crystallization for 30 seconds in the vacuum drying chamber with a pressure of 50 Pa and a temperature of 35 °C to obtain the perovskite precursor layer.

[0113] During the vacuum drying and crystallization process, FAI vapor is also introduced into the vacuum drying chamber of the vacuum drying device to carry out gas-phase conversion;

[0114] (3) In an air atmosphere, the perovskite precursor layer obtained in step (2) is subjected to heat treatment (annealing and phase fixation) at 80°C for 15 minutes to obtain a perovskite thin film.

[0115] Example 4

[0116] This embodiment provides a method for preparing a perovskite thin film. Except that the airflow speed during the purging in step (1) is 1 m / s and the purging time is extended so that the mass of the residual solvent in the wet film remains at 35% of the mass of the perovskite thin film obtained in step (3), the rest is the same as in Example 1.

[0117] Example 5

[0118] This embodiment provides a method for preparing a perovskite thin film. Except that the airflow speed during the purging in step (1) is 50 m / s and the purging time is shortened so that the mass of the residual solvent in the wet film remains at 35% of the mass of the perovskite thin film obtained in step (3), the rest is the same as in Example 1.

[0119] Example 6

[0120] This embodiment provides a method for preparing a perovskite thin film. Except that the airflow temperature during purging in step (1) is 10°C and the purging time is extended so that the mass of the residual solvent in the wet film remains at 35% of the mass of the perovskite thin film obtained in step (3), the rest are the same as in Example 1.

[0121] Example 7

[0122] This embodiment provides a method for preparing a perovskite thin film. Except that the airflow temperature during the purging in step (1) is 60°C and the purging time is extended so that the mass of the residual solvent in the wet film remains at 35% of the mass of the perovskite thin film obtained in step (3), the rest is the same as in Example 1.

[0123] Example 8

[0124] This embodiment provides a method for preparing a perovskite thin film. Except for step (1), in which the purging time is extended so that the mass of the residual solvent in the wet film is 10% of the mass of the perovskite thin film obtained in step (3), the rest are the same as in Example 1.

[0125] Example 9

[0126] This embodiment provides a method for preparing a perovskite thin film. Except for step (1), which shortens the purging time so that the mass of the residual solvent in the wet film is 70% of the mass of the perovskite thin film obtained in step (3), the rest is the same as in Example 1.

[0127] Example 10

[0128] This embodiment provides a method for preparing a perovskite thin film. Except for step (1), in which the slit width of the narrow-slit air knife is 0.2 mm, the rest is the same as in Example 1.

[0129] Example 11

[0130] This embodiment provides a method for preparing a perovskite thin film. Except for step (1), in which the slit width of the narrow-slit air knife is 2 mm, the rest is the same as in Example 1.

[0131] Example 12

[0132] This embodiment provides a method for preparing perovskite thin films. Except for the pressure of 1 Pa in the vacuum drying chamber in step (2), the rest is the same as in Example 1.

[0133] Example 13

[0134] This embodiment provides a method for preparing perovskite thin films. Except for the pressure of 100 Pa in the vacuum drying chamber in step (2), the rest is the same as in embodiment 1.

[0135] Example 14

[0136] This embodiment provides a method for preparing perovskite thin films. Except for omitting step (2) "during the vacuum drying and crystallization process, FAI vapor is introduced into the vacuum drying chamber of the vacuum drying device for gas phase conversion", the rest is the same as in embodiment 1.

[0137] Comparative Example 1

[0138] This comparative example provides a method for preparing a perovskite thin film. Except for omitting the step (1) of "purging the obtained slurry layer to evaporate part of the solvent and form a continuous pre-crystallized structure on the surface of the slurry layer to obtain a wet film that is both non-flowing and permeable to the pre-crystallized state", and omitting the step (1) of "slit coating the perovskite precursor slurry to obtain the slurry layer and then directly feeding it into the vacuum drying chamber of the vacuum drying device at a conveying speed of 0.5 m / min to 2 m / min for vacuum drying and crystallization", the rest is the same as in Example 1.

[0139] Application Example 1

[0140] This application example provides a fabrication process for a perovskite solar cell module, the fabrication process including:

[0141] (I) P1 was prepared by laser scribing on an FTO glass substrate with a planar size of 30cm×40cm;

[0142] (II) The FTO glass with P1 etched in step (I) is ultrasonically treated with deionized water, detergent and isopropanol for 15 min respectively;

[0143] (III) The cleaned FTO obtained in step (II) is dried with nitrogen to obtain an FTO substrate;

[0144] (IV) Deposit a hole transport layer (nickel oxide layer) on the FTO substrate obtained in step (III).

[0145] (V) On the surface of the hole transport layer obtained in step (IV), a perovskite thin film with a thickness of 650 nm is prepared using the preparation method provided in Example 1;

[0146] (VI) On the surface of the perovskite film obtained in step (V), an electron transport layer (C60 layer) with a thickness of 26 nm is deposited by vacuum method.

[0147] (VII) On the surface of the electron transport layer obtained in step (VI), a 16 nm SnO2 layer is deposited using atomic layer deposition.

[0148] (VIII) P2 is prepared by laser scribing on the SnO2 layer obtained in step (VII);

[0149] (IX) On the SnO2 layer with P2 etched in step (VIII), a copper layer with a thickness of about 200 nm is deposited by thermal evaporation;

[0150] (X) On the copper layer obtained in step (VII), P3 is laser-etched.

[0151] (XI) Encapsulation is performed to obtain perovskite solar cell modules.

[0152] Application Example 2

[0153] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 2, the rest are the same as in Example 1.

[0154] Application Example 3

[0155] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 3, all other steps are the same as in Example 1.

[0156] Application Example 4

[0157] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 4, the rest are the same as in Example 1.

[0158] Application Example 5

[0159] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 5, the rest are the same as in Example 1.

[0160] Application Example 6

[0161] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 6, the rest are the same as in Example 1.

[0162] Application Example 7

[0163] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 7, the rest are the same as in Example 1.

[0164] Application Example 8

[0165] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 8, the rest are the same as in Example 1.

[0166] Application Example 9

[0167] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 9, the rest are the same as in Example 1.

[0168] Application Example 10

[0169] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 10, the rest are the same as in Example 1.

[0170] Application Example 11

[0171] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 11, the rest are the same as in Example 1.

[0172] Application Example 12

[0173] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 12, the rest are the same as in Example 1.

[0174] Application Example 13

[0175] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 13, the rest are the same as in Example 1.

[0176] Application Example 14

[0177] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Example 14, the rest are the same as in Example 1.

[0178] Comparative Application Example 1

[0179] This application example provides a fabrication process for a perovskite solar cell module. Except for step (V), in which the perovskite thin film is prepared using the fabrication method provided in Comparative Example 1, the rest are the same as in Example 1.

[0180] The perovskite films obtained in the above examples and comparative examples were tested using an X-ray diffractometer. The XRD patterns of the perovskite films prepared by the methods provided in Example 2 and Comparative Example 1 are shown below. Figure 1 As shown.

[0181] The perovskite solar cell modules obtained from the above application examples and comparative application examples were tested using the following method: under standard test conditions (AM1.5G spectrum, 1000W / m²). 2 Under irradiance (cell temperature 25°C), the current-voltage characteristic curves of the perovskite solar cell modules were measured using a solar simulator and an IV test system. The open-circuit voltage (Vsc), short-circuit current (Isc), fill factor (FF), and conversion efficiency (PCE) of the perovskite solar cell modules are shown in Table 1. The current-voltage characteristic curves of the perovskite solar cell modules obtained using the fabrication processes provided in Application Example 2 and Comparative Application Example 1 are shown below. Figure 2 As shown.

[0182] Table 1

[0183]

[0184] From Table 1 and Figure 1 and Figure 2 We can obtain:

[0185] (1) The perovskite film prepared by the preparation method provided in Example 1 has a better crystal orientation and higher crystal quality;

[0186] The perovskite solar cell modules fabricated using the fabrication processes provided in Examples 1-3 exhibit high open-circuit voltage (48.46 V to 48.68 V), high short-circuit current (0.418 A), high fill factor (79.5% to 80.2%), and high conversion efficiency (21.0% to 21.2%).

[0187] (2) By comparing Example 1 with Examples 4 and 5, and by comparing Application Example 1 with Application Examples 4 and 5, it can be seen that in this invention, when the airflow speed during the purging in step (1) is 5m / s to 30m / s, the perovskite thin film and perovskite solar cell module exhibit better performance. This is because when the airflow speed is appropriate, it can balance the solvent evaporation rate and the film flatness. If the airflow speed is too slow, the solvent evaporation is slow, causing the wet film to flow continuously and unable to form a stable pre-crystallization quickly. If the airflow speed is too fast, the strong airflow disturbance will destroy the surface tension balance of the wet film, and the quality of the perovskite thin film will deteriorate.

[0188] (3) By comparing Example 1 with Examples 6 and 7, and by comparing Application Example 1 with Application Examples 6 and 7, it can be seen that in this invention, when the airflow temperature during the purging in step (1) is 20°C to 40°C, the perovskite thin film and perovskite solar cell module exhibit better performance. This is because a suitable airflow temperature can regulate the evaporation kinetics of the solvent. When the airflow temperature during purging is in this range, it helps to induce uniform nucleation and avoids film cracking and pores caused by thermal stress or excessive evaporation, thus ensuring the dense growth of the crystal.

[0189] (4) By comparing Example 1 with Examples 8 and 9, and by comparing Application Example 1 with Application Examples 8 and 9, it can be seen that in the present invention, when the residual solvent mass in the pre-crystallized wet film obtained in step (1) is 20% to 50% of the mass of the perovskite film obtained in step (3), the perovskite film and the perovskite solar cell module exhibit better performance. This is because the residual amount range makes the wet film in the best semi-solid state. When the residual solvent mass in the wet film is controlled within this range, the mechanical stability of the wet film is guaranteed, and sufficient mass transfer channels are retained for grain growth and defect healing, thereby improving the quality of the perovskite film.

[0190] (5) By comparing Example 1 with Examples 10 and 11, and by comparing Application Example 1 with Application Examples 10 and 11, it can be seen that in the present invention, when the width of the air knife of the narrow-slit air knife used in step (1) is 0.5mm to 1.0mm, the perovskite thin film and perovskite solar cell module exhibit better performance. This is because the appropriate air knife width ensures the laminar flow characteristics and pressure uniformity of the airflow. When the air knife width is in this range, a stable air curtain can be formed, ensuring the consistency of solvent evaporation on the surface of the large-area wet film and reducing the film thickness difference.

[0191] (6) By comparing Example 1 with Examples 12 and 13, and by comparing Application Example 1 with Application Examples 12 and 13, it can be seen that in this invention, when the vacuum drying crystallization in step (2) is carried out under a pressure of 5 Pa to 50 Pa, the perovskite thin film and the perovskite solar cell module exhibit better performance. This is because the pressure range provides a suitable solution supersaturation. Under this pressure, the solvent is orderly removed, which promotes the uniform formation and directional vertical growth of perovskite crystal nuclei, reduces grain boundary defects, and thus improves the quality of the perovskite thin film.

[0192] (7) By comparing Example 1 with Example 14 and Application Example 1 with Application Example 14, it can be seen that in the present invention, during the vacuum drying and crystallization process described in step (2), halide vapor is also introduced for gas-phase conversion. The specific type and ratio of the introduced halide vapor can be adjusted according to the target perovskite system. This treatment aims to utilize the halide vapor to react with the pre-crystallized wet film that is neither flowing nor permeable, to promote the formation of the perovskite precursor layer, while achieving halide replenishment and grain growth, thereby reducing film surface defects and enhancing the uniformity of the perovskite photovoltaic film.

[0193] (8) The perovskite solar cell module prepared by the preparation process provided in Examples 1 to 3 has an open-circuit voltage of 48.45V, a short-circuit current of 0.417A, a fill factor of 76.2% and a conversion efficiency of 20.3%.

[0194] By comparing Example 1 with Comparative Example 1, and by comparing Application Example 1 with Comparative Application Example 1, it can be seen that in the preparation method provided by the present invention, in step (1), purging is performed immediately after coating. The purging is used to quickly remove some of the highly volatile solvent from the surface of the slurry layer, induce the surface of the slurry layer to form a continuous pre-crystallized structure (the surface changes from a fluid state to a semi-solid state), and adjust the slurry layer from a highly solvent, easily flowing state to a state with a certain mechanical support and nucleation points, thereby forming a wet film in a pre-crystallized state that is neither flowing nor permeable. This avoids the bubbling, pinholes and stripe defects caused by instantaneous vaporization of solvent when the slurry layer is directly vacuum dried and crystallized in step (2), thereby improving the quality of the perovskite film.

[0195] In the preparation method provided by the present invention, the purging in step (1) can be carried out at atmospheric pressure, which can complete the densification and nucleation of the slurry layer surface without increasing the burden on the vacuum system, ensuring that the initial wet film in step (2) is in a uniform initial crystallization stage, thereby significantly improving the uniformity of the perovskite film. The perovskite film prepared has uniform grains and no obvious pinholes, thereby improving the uniformity of the perovskite solar cell module.

[0196] In the preparation method provided by the present invention, since a large amount of highly volatile solvent has been removed during the purging in step (1), the vacuum degree and halide vapor partial pressure in the vacuum drying equipment are more likely to remain stable during vacuum drying and crystallization in step (2), thereby shortening the vacuum drying and crystallization time or reducing the vacuum degree requirement, thus shortening the preparation method time and improving the production capacity of the production line.

[0197] In the preparation method provided by the present invention, the heat treatment in step (3) is used to eliminate the residual internal stress generated in the slurry layer during the pre-crystallization and vacuum drying crystallization process, promote the growth of perovskite grains, crystal rearrangement and crystal phase densification, and stabilize the perovskite phase structure, thereby obtaining a dense perovskite film with good light activity, and improving the open circuit voltage, fill factor and stability of the perovskite solar cell module.

[0198] The preparation method provided by this invention has good compatibility with existing air coating production lines. It only requires adding a purging process after the existing coating process and connecting it normally with the existing sequential vacuum drying, crystallization and heat treatment processes to complete the modification. It is suitable for component-level, roll-to-roll and large-area production.

[0199] In summary, the preparation method provided by this invention introduces a purging step after coating and before vacuum drying and crystallization, which forms a pre-crystallized structure on the surface of the slurry layer that is both non-flowing and permeable. This effectively overcomes defects such as blistering and pinholes caused by direct vacuum drying, optimizes the solvent evaporation process, and significantly shortens the vacuum drying time. Therefore, the preparation method has high efficiency, and the prepared titanium dioxide film has high quality, excellent uniformity, and improved thickness.

[0200] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a perovskite thin film, characterized in that, The preparation method includes: (1) The slurry layer formed after the perovskite precursor slurry is coated is purged so that some of the solvent evaporates and a continuous pre-crystallized structure is formed in the surface of the slurry layer, so as to obtain a wet film in a pre-crystallized state that is neither flowing nor permeable. The pre-crystallized structure is a semi-solid layer formed by the dynamic transformation of the surface of the slurry layer; (2) The pre-crystallized wet film obtained in step (1) is subjected to vacuum drying and crystallization to obtain a perovskite precursor layer. (3) Heat-treat the perovskite precursor layer obtained in step (2) to obtain a perovskite thin film; In the pre-crystallized wet film described in step (1), which is neither flowable nor permeable, the residual solvent mass is 20% to 50% of the mass of the perovskite film obtained in step (3). In step (2), during the vacuum drying and crystallization process, halide vapor is also introduced for gas phase conversion. The halide vapor includes any one or at least a combination of two of FAI vapor, MAI vapor, CsI vapor or MABr vapor.

2. The preparation method according to claim 1, characterized in that, In step (1), the airflow velocity during purging is 5m / s to 30m / s, the airflow temperature is 20℃ to 40℃, the tangential angle or downward blowing angle of the airflow direction relative to the surface of the slurry layer is 45° to 70°, and the purging time is 1s to 5s.

3. The preparation method according to claim 1, characterized in that, The purging in step (1) is carried out using at least one narrow-slit air knife, the slit width of which is 0.5mm~1.0mm and the distance between the air knife and the surface of the slurry layer is 20mm~40mm; During the purging process described in step (1), dry nitrogen, dry air, or nitrogen mixed with low-boiling-point solvent vapor is used to purge the obtained slurry layer.

4. The preparation method according to claim 1, characterized in that, The vacuum drying crystallization in step (2) is carried out under a pressure of 5 Pa to 50 Pa, a temperature of 20°C to 35°C, and a time of 30 s to 70 s.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The heat treatment in step (3) is carried out at a temperature of 80℃~180℃ for 5min~15min in an air atmosphere.

6. A perovskite thin film, characterized in that, The perovskite thin film is obtained by the preparation method according to any one of claims 1 to 5.

7. A fabrication process for a perovskite solar cell module, characterized in that, The preparation process includes: When preparing perovskite thin films for large-area perovskite photovoltaic modules, the preparation method described in any one of claims 1 to 5 shall be used.

8. A perovskite solar cell module, characterized in that, The perovskite solar cell module is obtained by the fabrication process described in claim 7.

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