Flexible perovskite cell and preparation method therefor

Abstract

Provided in the present invention are a flexible perovskite cell and a preparation method therefor. The preparation method for a flexible perovskite cell comprises: providing two flexible substrates; sequentially forming a conductive layer, a first carrier transport layer and a perovskite layer on one of the two flexible substrates, so as to serve as a first layer to be assembled; sequentially forming a conductive layer, a second carrier transport layer and a perovskite layer on the other flexible substrate, so as to serve as a second layer to be assembled; and relatively laminating the perovskite layer of said first layer with the perovskite layer of said second layer to form a single perovskite layer, such that said first layer and said second layer are assembled into a perovskite solar cell. The preparation method for a flexible perovskite cell in the present invention facilitates parallel operations, thereby improving the preparation efficiency; moreover, the preparation method can effectively ensure the bonding strength, thereby making the flexible perovskite cell tear-resistant and peel-resistant; and the obtained flexible perovskite cell also has good water resistance and good resistance to organic solvent erosion.

Description

Flexible perovskite solar cells and their fabrication methods Technical Field

[0001] This invention relates to the field of perovskite optoelectronic device technology, specifically to a flexible perovskite solar cell and its fabrication method. Background Technology

[0002] With the increasing deterioration of the environment, the development of efficient and clean renewable energy sources is urgently needed. In recent years, organic-inorganic hybrid perovskite solar cells have attracted widespread attention from researchers due to their excellent photoelectric properties, and their efficiency has approached that of crystalline silicon solar cells, reaching 26.1%. In addition, because perovskite solar cells are fabricated using low-temperature processes, they are well compatible with flexible plastic substrates, making them an ideal material for realizing high-efficiency flexible solar cells.

[0003] Compared to rigid perovskite solar cells, flexible perovskite solar cells have broad application prospects in portable mobile devices, building-integrated photovoltaics, and aerospace due to their excellent flexibility and light weight. However, current high-efficiency devices are based on spin-coating processes to fabricate functional layers on a single-layer substrate. This method cannot be used for the fabrication of large-area flexible solar cells and is difficult to mass-produce, resulting in low production efficiency. Summary of the Invention

[0004] To achieve mass industrial production of large-area flexible perovskite solar cells, this invention provides a flexible perovskite solar cell and its preparation method.

[0005] This invention provides a method for preparing a flexible perovskite solar cell.

[0006] Two flexible substrates are provided;

[0007] A conductive layer, a first carrier transport layer, and a perovskite layer are sequentially formed on one of the two flexible substrates as the first layer to be assembled.

[0008] A conductive layer, a second carrier transport layer, and a perovskite layer are sequentially formed on one of the two flexible substrates as the second layer to be assembled.

[0009] The perovskite layers of the first layer to be assembled and the second layer to be assembled are pressed together to form a single perovskite layer, thereby assembling the first layer to be assembled and the second layer to be assembled into a perovskite solar cell.

[0010] The first carrier transport layer and the second carrier transport layer are selected from one of the electron transport layer and the hole transport layer, respectively.

[0011] Preferably, the perovskite layer on the first layer to be assembled and the perovskite layer on the second layer to be assembled are formed by coating with a perovskite precursor solution, and the perovskite layer undergoes a crystallization process during relative compression.

[0012] Preferably, the first layer to be assembled forms the light-facing surface of the perovskite solar cell, and the second layer to be assembled forms the back-facing surface of the perovskite solar cell;

[0013] The conductive layer formed in the second layer to be assembled includes a second electrode layer and a current collector network formed by metal electrodes in the second electrode layer;

[0014] The conductive layer formed in the first layer to be assembled includes an electrode layer.

[0015] Preferably, the materials of the electrode layer and the second electrode layer are selected from at least one of indium tin oxide, fluorine-doped indium tin oxide, antimony-doped indium tin oxide, and aluminum-doped zinc oxide.

[0016] Preferably, the electrode layer and the second electrode layer are formed by magnetron sputtering.

[0017] Preferably, the step of forming the conductive layer in the second layer to be assembled is as follows:

[0018] A patterned metal electrode is formed on one side surface of the flexible substrate of the second layer to be assembled, and the metal electrode is distributed on the surface of the flexible substrate.

[0019] An electrode layer is formed on the surface of a flexible substrate on which metal electrodes are formed.

[0020] Preferably, both the flexible substrate of the first layer to be assembled and the conductive layer of the first layer to be assembled are light-transmitting materials.

[0021] Preferably, both the flexible substrate of the first layer to be assembled and the conductive layer of the first layer to be assembled are transparent materials.

[0022] Preferably, the flexible substrate is made of at least one of polyethylene terephthalate and polyimide.

[0023] The present invention also provides a flexible perovskite solar cell, which is formed by pressing a first layer to be assembled and a second layer to be assembled together;

[0024] The first layer to be assembled includes a flexible substrate, a conductive layer, a first carrier transport layer and a perovskite layer formed in sequence.

[0025] The first layer to be assembled includes a flexible substrate, a conductive layer, a second carrier transport layer, and a perovskite layer formed in sequence.

[0026] During lamination, the perovskite layer of the first layer to be assembled is opposite to the perovskite layer of the second layer to be assembled, and a single perovskite crystalline layer is formed after lamination.

[0027] Preferably, the first layer to be assembled forms the light-facing surface of the perovskite solar cell, and the second layer to be assembled forms the back-facing surface of the perovskite solar cell;

[0028] The flexible substrate and conductive layer of the first layer to be assembled are light-transmitting materials.

[0029] The flexible perovskite solar cell fabrication method of the present invention is advantageous for improving fabrication efficiency because the fabrication processes of the first layer to be assembled and the second layer to be assembled are independent of each other and can be operated in parallel. Then, a pressing process is performed. Therefore, it can significantly improve the fabrication efficiency compared to the fabrication method that simply forms each functional layer sequentially on a single substrate.

[0030] The flexible perovskite solar cell fabrication method of this invention achieves bonding between the first and second perovskite layers during and after pressing, which is essentially the encapsulation of the perovskite solar cell. The two perovskite layers are ultimately bonded into a single perovskite layer without a clear interface, effectively ensuring bonding strength. No additional adhesive is needed to guarantee a reliable overall bonding of the perovskite solar cell across its entire surface, making it tear-resistant and peel-resistant.

[0031] The flexible perovskite solar cell fabrication method of the present invention has a double-sided double-layer substrate, and the flexible solar cell also has good waterproof and organic solvent erosion resistance. Attached Figure Description

[0032] Figure 1 is a schematic diagram of the structure of a perovskite solar cell in the prior art;

[0033] Figure 2 is a schematic diagram of the perovskite solar cell structure of the present invention;

[0034] Figure 3 is a detailed schematic diagram of the perovskite solar cell of the present invention;

[0035] Figure 4 is a schematic diagram of the metal electrode 121 of the first layer A1 to be assembled in the perovskite solar cell of the present invention;

[0036] Figure 5 is a schematic diagram of the pressing process of the perovskite solar cell of the present invention;

[0037] Figure 6 is a schematic diagram of the conductive layer 12 of the first layer A1 to be assembled in the perovskite solar cell of the present invention.

[0038] Figure 7 is another schematic diagram of the pressing process of the perovskite solar cell of the present invention;

[0039] Figure 8 is a schematic diagram of the continuous production line of the perovskite solar cell of the present invention.

[0040] In the picture:

[0041] 1: Perovskite solar cell; 11: Flexible substrate; 111: First flexible substrate; 112: Second flexible substrate; 12: Conductive layer; 121: Metal electrode; 122: Electrode layer; 123: Second electrode layer; 13: Electron transport layer; 14: Perovskite layer; 15: Hole transport layer; A1: First layer to be assembled; B1: Second layer to be assembled; W1: Pressure roller. Embodiments of the present invention

[0042] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. In this specification, the dimensions in the drawings do not represent actual size proportions. The drawings are only used to illustrate the relative positional and connection relationships between the components. Components with the same name or the same reference numerals represent similar or identical structures and are limited to illustrative purposes.

[0043] Since perovskite was first used as a sensitizer in dye-sensitized solar cells in 2009, achieving a photovoltaic efficiency of approximately 4%, research on perovskite solar cells has progressed rapidly. Currently, the photovoltaic efficiency of perovskite solar cells has exceeded 26%, approaching that of crystalline silicon solar cells. Due to the relatively simple fabrication process and low energy consumption of perovskite solar cells, they have become a key category of next-generation solar cells.

[0044] Perovskite solar cells have relatively low requirements for substrate materials. Flexible perovskite solar cells and other flexible perovskite optoelectronic devices can be fabricated by using various organic thin-film materials as substrates. Currently, the fabrication of flexible perovskite cells generally involves directly forming a functional layer on a flexible substrate.

[0045] This invention first attempts to improve the fabrication efficiency of existing flexible perovskite solar cells, and to this end, it provides a targeted fabrication method for flexible perovskite solar cells, which also provides a flexible perovskite solar cell with an improved structure.

[0046] In a typical example of a conventional flexible perovskite solar cell 1, as shown in Figure 1, an electron transport layer 13, a perovskite layer 14, and a hole transport layer 15 are stacked and contacted together. Under sunlight, charge carriers in the perovskite layer 14 migrate in a specific direction, with electrons flowing towards the electron transport layer 13 and holes flowing towards the hole transport layer 15, creating a potential difference across the layered structure formed by the electron transport layer 13, perovskite layer 14, and hole transport layer 15. Based on this, conductive layers 12 are formed on the surface of the electron transport layer 13 and the hole transport layer 15. Connecting the two conductive layers 12 in a circuit allows current to flow in the circuit. Generally, each of the above layers requires a structural support layer, namely a flexible substrate 11 formed on the surface of any conductive layer 12. The prior art also reports perovskite solar cells without hole transport layer 15 with high photoelectric conversion efficiency. Therefore, in the above-mentioned layered perovskite solar cells, hole transport layer 15 can also be removed, and conductive layer 12 can be directly stacked on the surface of perovskite layer 14 to form a conductive layer.

[0047] In a flexible perovskite solar cell 1 with the structure described above, the layers are generally formed sequentially, which is not conducive to improving production efficiency. Therefore, this invention presents the structure of the perovskite solar cell 1 shown in Figure 2. This perovskite solar cell 1 has a double-layer flexible substrate 11, with each flexible substrate 11 formed on the surface of a corresponding conductive layer 12. The presence of the double-layer flexible substrate 11 not only provides double-sided support and protection for the perovskite solar cell 1, but also provides a basis for subsequent process optimization. In other words, by applying a double-sided double-layer flexible substrate 11, the original method of concentrating all functional layers on a single flexible substrate 11 and forming them sequentially can be modified to simultaneously forming different functional layers on two separate flexible substrates 11, and then combining them into a single perovskite solar cell 1. The improved process is expected to significantly improve the fabrication efficiency of the perovskite solar cell 1.

[0048] Furthermore, Figure 3 shows the structural details of the improved perovskite solar cell 1. The perovskite solar cell 1 has a clearly defined light-facing side (the side closest to the light source relative to the perovskite layer 14, directly receiving sunlight) and a back-light side (the side furthest from the light source relative to the perovskite layer 14). Typically, to ensure photoelectric conversion efficiency, the requirements for the flexible substrate 11 and conductive layer 12 on the light-facing and back-light sides differ. For the flexible substrate 11 and conductive layer 12 on the light-facing side, they are preferably transparent to ensure sufficient light intake for the perovskite layer 14. In practical applications, the flexible substrate 11 and conductive layer 12 on the light-facing side are generally formed using transparent materials. Therefore, the conductive layer 12 is generally a second electrode layer 123, while the flexible substrate 11 is generally a transparent flexible substrate. For the flexible substrate 11 and conductive layer 12 on the back-light side, there are generally no requirements for light transmission. Of course, this is different if it is used in perovskite-silicon tandem cells or other applications requiring the reuse of residual light. In this case, in addition to being formed by the electrode layer 122, the conductive layer 12 on the backlight surface preferably has a current-collecting network formed by patterned metal electrodes 121 formed in 122 to achieve higher current-collecting efficiency. The metal electrodes 121 are preferably silver or silver alloys to provide good conductivity. As shown in Figure 4, the pattern of the metal electrodes 121 can be parallel lines, triangles, rectangles, hexagons, honeycomb, etc., tiling the electrode layer 122.

[0049] Based on the improved perovskite solar cell 1 structure described above, this invention provides the following fabrication method. First, two flexible substrates 11 are provided, and then functional layers are formed on each of the two flexible substrates 11. Specifically, a flexible substrate 11, a conductive layer 12, an electron transport layer 13, and a perovskite layer 14 are sequentially stacked and contact-formed on one substrate to obtain a second layer to be assembled, B1. A flexible substrate 11, a conductive layer 12, a hole transport layer 15, and a perovskite layer 14 are stacked and contact-formed on the other flexible substrate 11 to obtain a first layer to be assembled, A1. Then, the perovskite layers 14 of the first layer to be assembled, A1, and B1 are respectively bonded together, and the first layer to be assembled, A1, and B1 are pressed together to form the perovskite solar cell 1. It should be noted that the perovskite layer 14 is generally obtained by coating a precursor solution onto the surface of the formed material. After the solvent in the precursor solution evaporates, it crystallizes to form a stable perovskite layer. Therefore, the process of bonding and pressing the perovskite layers 14 of the first layer A1 and the second layer B1 together should preferably be carried out before the perovskite layers 14 have completed crystallization. Since the perovskite layers 14 have not yet fully crystallized, during the pressing process, the perovskite layers 14 of different layers can form a stable single-structure perovskite layer 14 as they continue to crystallize. Based on the formed perovskite layer 14, a single perovskite solar cell 1 can be formed between the first layer A1 and the second layer B1 without the need for additional adhesive bonding. The formed perovskite solar cell 1 has good bonding between layers, just like the functional layers are sequentially stacked on a single-layer flexible substrate 11.

[0050] The following is a specific implementation of the above preparation method. As shown in Figure 5, in the preparation process of this embodiment, the first layer to be assembled, A1, mainly forms the functional layer of the light-facing side of the perovskite solar cell 1, while the second layer to be assembled, B1, mainly forms the functional layer of the back side of the perovskite solar cell 1.

[0051] S1. Select two flexible substrates 11. For ease of description, the two flexible substrates 11 are labeled as the first flexible substrate 111 (facing the light) and the second flexible substrate 112 (facing the back light). The material of the flexible substrates 11 can be selected from organic polymer films such as polyethylene terephthalate and polyimide. The first flexible substrate 111 is preferably made of a transparent polymer film to ensure the intensity of light passing through the flexible substrate 11 and irradiating the perovskite layer 14, thereby improving the light reception and photoelectric conversion efficiency of the perovskite layer 14. Obviously, the first flexible substrate 111 is preferably a transparent film in the conventional sense.

[0052] S2. Form the first layer to be assembled, A1. A conductive layer 12, a hole transport layer 15, and a perovskite layer 14 are sequentially formed on one side of the first flexible substrate 111 as the first layer to be assembled, A1.

[0053] The specific steps are as follows:

[0054] S21. A conductive layer 12 is formed on one side of the first flexible substrate 111. In this embodiment, the conductive layer 12 formed on the first flexible substrate 111 is designated as the second electrode layer 123. The material composition of the second electrode layer 123 may include indium tin oxide (ITO), fluorine-doped indium tin oxide (FTO), antimony-doped indium tin oxide (ATO), and aluminum-doped zinc oxide (AZO), etc. The conductive layer 12 is preferably transparent. The second electrode layer 123 can be prepared by magnetron sputtering on the surface of the first flexible substrate 111.

[0055] S22. A hole transport layer 15 is formed on the surface of the conductive layer. Here, a hole transport layer 15 made of nickel oxide (NiOx) is used as an example. It is formed by magnetron sputtering and has a thickness of 5-20 nm. After formation, it is annealed in air for 20 min. Next, the NiOx hole transport layer undergoes a self-assembly layer surface treatment to obtain a modified NiOx hole transport layer for device fabrication.

[0056] S23. Forming a perovskite layer on the surface of the hole transport layer. First, prepare a precursor solution for the perovskite light-absorbing layer by adding 6533 μL of N,N-dimethylformamide (DMF) and 1633 μL of dimethyl sulfoxide (DMSO) to 1600 mg formamidinium iodide (FAI), 127.4 mg cesium iodide (CsI), and 4517.8 mg lead iodide (PbI2). The dissolution process can be carried out at room temperature (0-25℃) and may take 2 hours or longer, depending on the situation. Then, uniformly spray the obtained perovskite precursor solution onto the surface of the hole transport layer 15 of the first layer to be assembled, A1.

[0057] S3. Forming the second layer to be assembled B1. A conductive layer 12, an electron transport layer 13, and a perovskite layer 14 are sequentially stacked on one side surface of the second flexible substrate 112 as the second layer to be assembled B1.

[0058] The specific steps are as follows:

[0059] S31. A conductive layer 12 is formed on one side surface of the second flexible substrate 112. The conductive layer 12 may consist solely of an electrode layer 122. The electrode layer 122 is primarily used to collect electrons transported in the electron transport layer 13 and drive them to flow in the external circuit, forming a current. The main materials of the electrode layer 122 include conductive materials such as indium tin oxide (ITO), fluorine-doped indium tin oxide (FTO), antimony-doped indium tin oxide (ATO), and aluminum-doped zinc oxide (AZO). To improve the current collection capability of the conductive layer 12, a metal electrode 121 can be formed in or on the surface of the electrode layer 122 to achieve high-efficiency carrier collection. The metal electrode 121 is generally only disposed in the conductive layer on the side of the second layer to be assembled, B1. Generally, it is not recommended to form the metal electrode 121 in the first layer to be assembled, A1, as this may affect the transmittance of the device, thereby affecting the photoelectric conversion efficiency of the solar cell. Specifically, the conductive layer 12 can be formed using the following process.

[0060] First, a patterned metal electrode 121 is deposited on one side surface of the second flexible substrate 112 according to a predetermined pattern. Then, an electrode layer 122 is formed on the surface of the second flexible substrate 112 where the metal electrode 121 has been deposited. The metal electrode 121 can be deposited by thermal evaporation, where the vacuum level is below 2 × 10⁻⁴ Pa and the deposition rate is 3 Å / s. The electrode layer 122 is generally formed by magnetron sputtering. The thickness of the formed electrode layer 122 and the aforementioned second electrode layer 123 is 170 nm, and the sheet resistance is 19 ohms. Referring to the cross-sectional schematic diagram in Figure 6, the metal electrode 121 is formed on the surface of the conductive layer 12.

[0061] S32. An electron transport layer 13 is formed on the surface of the conductive layer 12. A precursor solution for the electron transport layer is obtained by diluting a tin dioxide colloidal mother liquor. This precursor solution is then coated onto the surface of the conductive layer 12 formed on the second flexible substrate 112 and annealed to obtain the electron transport layer. The process of preparing the precursor solution for the electron transport layer involves taking a certain amount of tin dioxide (SnO2) colloidal mother liquor, diluting it 6.6 times with deionized water, and mixing for 5 minutes to obtain the precursor solution (SnO2 solution) for the electron transport layer. The annealing conditions are annealing at 100 °C for 40 minutes under vacuum conditions. However, the annealing conditions are not unique; for example, annealing at 150 °C for 5 minutes is also acceptable. Preferably, the SnO2 electron transport layer can be surface-treated with acetic acid to obtain a modified SnO2 electron transport layer for device manufacturing.

[0062] S33. A perovskite layer is formed on the surface of the electron transport layer. The perovskite layer 14 is formed by coating with a perovskite precursor solution. First, a perovskite precursor solution is prepared by adding 6533 μL of N,N-dimethylformamide (DMF) and 1633 μL of dimethyl sulfoxide (DMSO) to 1600 mg formamidinium iodide (FAI), 127.4 mg cesium iodide (CsI), and 4517.8 mg lead iodide (PbI2), and dissolving at room temperature for 2 hours to obtain the perovskite precursor solution. Then, the dissolved perovskite precursor solution is uniformly sprayed onto the surface of the electron transport layer 13 of the second layer to be assembled, B1.

[0063] The steps of forming the first layer A1 to be assembled in S2 and forming the second layer B1 to be assembled in S3 can actually be carried out without interference, which means that it is possible to carry out the two steps simultaneously, thus effectively improving the fabrication efficiency of perovskite solar cells.

[0064] Generally, depending on the production sequence and interval, the surface of the substrate material can be cleaned before forming any layer. For example, before forming the conductive layer 12 on the flexible substrate 11, it is advisable to clean the flexible substrate 11 in advance. The specific process can be to ultrasonically clean it with acetone and isopropanol for 25 minutes respectively, and then dry the surface of the flexible substrate 11 with nitrogen.

[0065] During the process of forming the perovskite layer 14 on the surface of the electron transport layer 13 and the perovskite layer 15 on the surface of the hole transport layer 15, the surfaces of the electron transport layer 13 and the hole transport layer 15 can be cleaned in advance. The cleaning method can be ultraviolet ozone treatment, and the time can be flexibly determined, such as 15 minutes.

[0066] Furthermore, when fabricating the perovskite layer 14 on the surface of the electron transport layer 13, a functionalized interface material can be introduced onto the surface of the electron transport layer 13. Alternatively, a functionalized interface material can be introduced onto the surface of the hole transport layer 15 before fabricating the perovskite layer 14. The material for the functional layer at the electron transport layer 13 is not limited to halides or metal fluorides, and is formed through coating or thermal evaporation. The material for the functional layer at the hole transport layer 15 is not limited to organic acids and their derivatives, halides, etc., and is formed through coating or thermal evaporation. The function of the functional layers is to regulate energy level matching and passivate interface defects.

[0067] The perovskite layer 14 in S23 and S33 can also be obtained as follows: Butylamine iodine, methylamine iodine, and lead iodide in a ratio of 2:4:5 are dissolved in a DMSO / DMF solvent in a ratio of 1:9, with a concentration of 0.8 M. The solution is annealed at 90°C for 5 min. This precursor solution is then coated onto the surfaces of the electron transport layer 13 and the hole transport layer 15 to obtain the corresponding perovskite layer 14. This method facilitates the preparation of quasi-two-dimensional perovskite layers. When using two-dimensional perovskite, this technique enables the fabrication of two-dimensional / three-dimensional heterojunction perovskite solar cells and allows for more flexible control over the thickness of the two-dimensional material.

[0068] The perovskite layer 14 in S23 and S33 can also be obtained as follows: A certain amount of lead iodide is dissolved in DMF solvent at a concentration of 1.0 M. Formamidinium iodide, methylamine iodide, and methylamine chloride are dissolved in IPA solvent in a ratio of 90:6.2:9. These two precursor solutions are respectively coated onto the surfaces of electron transport layer 13 and hole transport layer 15, and annealed at 150°C for 10 min to obtain the corresponding perovskite layer 14. This method is a two-step process to obtain the perovskite layer. Using this two-step method, this technology can realize the fabrication of high-efficiency nip-type perovskite solar cells.

[0069] The above describes a scheme where the hole transport layer is placed on the light-facing side. However, it is also possible to place the hole transport layer on the back-facing side and the electron transport layer on the light-facing side. In other words, in this embodiment, a first carrier transport layer, a perovskite layer 14, and a second carrier transport layer are formed sequentially from the back-facing side to the light-facing side, wherein the first carrier transport layer and the second carrier transport layer are respectively selected from one of the electron transport layer 13 and the hole transport layer 15.

[0070] S4. Combine the first layer to be assembled A1 and the second layer to be assembled B1 to obtain a flexible perovskite solar cell.

[0071] As shown in Figure 7, during the bonding process, the perovskite layer 14 of the first layer to be assembled A1 and the perovskite layer 14 of the second layer to be assembled B1 are positioned opposite each other. The first layer to be assembled A1 and the second layer to be assembled B1 are simultaneously fed into the gap between two pressure rollers W1. Under the action of the two pressure rollers, the first layer to be assembled A1 and the second layer to be assembled B1 are assembled into a flexible perovskite solar cell with a multilayer structure. In this scheme, the perovskite layers 14 formed on the first layer to be assembled A1 and the second layer to be assembled B1 are directly assembled using the bonding layers as bonding layers. After crystallization, the two perovskite layers 14 are finally bonded into a single-layer perovskite layer 14 without a clear interface, which effectively ensures the bonding force between the first layer to be assembled A1 and the second layer to be assembled B1. No additional adhesive is needed to ensure that the entire perovskite solar cell 1 is reliably bonded as a whole, resistant to tearing and peeling. Moreover, due to the double-sided double-layer substrate, this flexible solar cell also has good waterproof and organic solvent resistance.

[0072] Typically, during the pressing process of the first layer A1 and the second layer B1 to be assembled, a thermal annealing treatment of the perovskite layer 14 is also performed simultaneously. This allows the perovskite precursor solutions coated on the first flexible substrate 111 and the second flexible substrate 112 to undergo or complete the crystallization process during the thermal annealing and pressing process, forming the perovskite layer 14. Since the crystallization process of the precursor solution of the perovskite layer 14 occurs during the pressing process or is completed after pressing, the perovskite layer 14, which was originally separate in the first layer A1 and the second layer B1 and was still an uncrystallized perovskite precursor solution, will form a crystalline and shaped perovskite layer 14 during or after pressing. In particular, to accelerate the crystallization process of the perovskite layer 14, nitrogen gas can be introduced onto the surface of the perovskite layer 14 during the pressing process to accelerate the evaporation of the solvent. At this point, the perovskite layer 14 forms a monolithic layered structure, i.e., a single perovskite layer 14. Simultaneously, this single perovskite layer 14 completes the assembly and encapsulation between the first layer to be assembled, A1, and the second layer to be assembled, B1. Compared to methods that use adhesives locally, this method offers better overall integrity because the finished product lacks a clear interface between the two assembled layers. The presence of an interface during assembly does not affect the battery's conductivity and photoelectric conversion efficiency. Furthermore, the two assembled layers are surface-bonded without a specific delamination structure, thus preventing localized peeling or delamination at the bonding surface during use. This method also eliminates the need for adhesives on the bonding surface, either locally or entirely, to encapsulate the first layer to be assembled, A1, and the second layer to be assembled, B1.

[0073] The above-described preparation method also provides a new preparation process with significantly improved efficiency. Referring to Figure 8, a roll-to-roll continuous preparation process based on separate continuous coating and then lamination can be used to achieve large-scale continuous large-area preparation of perovskite solar cells 1. In this production process, a roll of thin film substrate is provided as a flexible substrate 11. The continuous process design is arranged according to the process conditions. For example, if it is difficult to integrate the conductive layer 12 formed by magnetron sputtering into the continuous line, the formation process of the conductive layer 12 can be separated from the production line, and the roll of thin film substrate with the conductive layer 12 formed can be directly provided as raw material. The raw material roll of thin film substrate is provided by two feed rollers and forms the first layer to be assembled A1 and the second layer to be assembled B1 corresponding to the above process through two coating lines. At least in the last process, the two coating lines coat the perovskite precursor solution on opposite sides of the thin film substrate to form a perovskite layer 14. Other processes can also be set between the coating lines and the coating of the perovskite layer 14, such as a coating process for forming the electron transport layer 13. If feasible, a coating process for forming the hole transport layer 15 can also be set. If the preparation of the metal electrode 121, electrode layer 122, and second electrode layer 123 allows for continuous production, for example, the electrode layer 122 or the second electrode layer 123 can be formed by coating, and the metal electrode 121 can be formed by printing, then the formation process of the conductive layer 12 can also be integrated into the coating line. In this case, the feeding roller is only used to provide the film substrate roll, rather than the film substrate roll with several material layers pre-formed.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a flexible perovskite solar cell, comprising: providing two flexible substrates (11) ; forming, on one of the two flexible substrates, a conductive layer (12), a first carrier transport layer, and a perovskite layer (14) in sequence as a first layer to be assembled (A1) ; forming, on the other of the two flexible substrates, a conductive layer (12), a second carrier transport layer, and a perovskite layer (14) in sequence as a second layer to be assembled (B1) ; pressing the perovskite layers (14) of the first layer to be assembled (A1) and the second layer to be assembled (B1) to form a single perovskite layer, and assembling the first layer to be assembled (A1) and the second layer to be assembled (B1) to form a perovskite solar cell (1) ; wherein the first carrier transport layer and the second carrier transport layer are selected from one of an electron transport layer (13) and a hole transport layer (15). The perovskite layers (14) on the first layer to be assembled (A1) and the second layer to be assembled (B1) are formed by coating a perovskite precursor solution, and the perovskite layers (14) undergo a crystallization process during the pressing. The perovskite precursor solution is obtained by dissolving formamidinium iodide, cesium iodide, and lead iodide in a mixed solution of N, N-dimethylformamide and dimethyl sulfoxide. The precursor solution includes a first precursor solution coated on the first layer to be assembled (A1) and a second precursor solution coated on the second layer to be assembled (B1). The first precursor solution is obtained by dissolving lead iodide in dimethyl sulfoxide. The second precursor solution is obtained by dissolving formamidinium iodide, methylamine iodide, and methylamine chloride in isopropanol.

2. The method for preparing a flexible perovskite solar cell as described in claim 1, characterized in that, The first layer to be assembled (A1) forms a light-receiving surface of the perovskite solar cell (1), and the second layer to be assembled (B1) forms a back surface of the perovskite solar cell (1).

3. The method for preparing a flexible perovskite solar cell as described in claim 2, characterized in that, The conductive layer (12) formed in the second layer to be assembled (B1) includes a second electrode layer (123) and a current collecting network formed by a metal electrode (121) in the second electrode layer (123).

4. The method for preparing a flexible perovskite solar cell as described in claim 2, characterized in that, The conductive layer (12) formed in the first layer to be assembled (A1) includes an electrode layer (122). The electrode layer (122) and the second electrode layer (123) are made of at least one of indium tin oxide, fluorine-doped indium tin oxide, antimony-doped indium tin oxide, and aluminum-doped zinc oxide. The electrode layer (122) and the second electrode layer (123) are formed by magnetron sputtering.

5. The method for preparing a flexible perovskite solar cell as described in claim 1 or 2, characterized in that, The conductive layer (12) in the second layer to be assembled (B1) is formed by: forming a patterned metal electrode (121) on one side surface of the flexible substrate of the second layer to be assembled (B1), the metal electrode (121) being distributed on the surface of the flexible substrate; and forming an electrode layer (122) on the surface of the flexible substrate on which the metal electrode (121) is formed. The flexible substrate of the first layer to be assembled (A1) and the conductive layer (12) of the first layer to be assembled (A1) are both light-transmitting materials. The flexible substrate of the first layer to be assembled (A1) and the conductive layer (12) of the first layer to be assembled (A1) are both transparent materials.

6. The method for preparing a flexible perovskite solar cell as described in claim 5, characterized in that, ​ 7. The method for preparing a flexible perovskite solar cell as described in claim 6, characterized in that, ​ 8. The method for preparing a flexible perovskite solar cell as described in claim 5, characterized in that, ​ ​ ​ 9. The method for preparing a flexible perovskite solar cell as described in claim 5, characterized in that, ​ 10. The method for preparing a flexible perovskite solar cell as described in claim 5, characterized in that, ​ 11. The method for preparing a flexible perovskite solar cell as described in claim 5, characterized in that, The material of the flexible substrate is at least one of polyethylene terephthalate, polyimide.

12. A flexible perovskite cell characterized in that, The first layer to be assembled (A1) and the second layer to be assembled (B1) are pressed to form a perovskite solar cell (1); The first layer to be assembled (A1) comprises a flexible substrate (11), a conductive layer (12), a first carrier transport layer and a perovskite layer (14) formed in sequence; The first layer to be assembled (A1) comprises a flexible substrate (11), a conductive layer (12), a second carrier transport layer and a perovskite layer (14) formed in sequence; During pressing, the perovskite layer (14) of the first layer to be assembled (A1) is opposite to the perovskite layer (14) of the second layer to be assembled (B1), and a single perovskite layer (14) crystalline layer is formed after pressing.

13. A flexible perovskite cell characterized in that, The first layer to be assembled (A1) forms the light-receiving surface of the perovskite solar cell (1), and the second layer to be assembled (B1) forms the back surface of the perovskite solar cell (1); The flexible substrate (11) and the conductive layer (12) of the first layer to be assembled (A1) are light-transmitting materials.

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