Perovskite interface modification layer, perovskite cell, preparation method of perovskite cell and laminated cell

Abstract

The invention provides a perovskite interface modification layer, a perovskite cell, a preparation method of the perovskite cell and a laminated cell. The perovskite interface modification layer comprises polyvinyl alcohol and borax, a dynamic boric acid ester cross-linking bond is formed between hydroxyl in the polyvinyl alcohol and boric acid radical ions hydrolyzed by the borax, and the boric acid ester cross-linking bond is broken when the temperature is greater than or equal to 40 DEG C and is rebuilt when the temperature is less than 40 DEG C. Therefore, a borate crosslinking bond in the perovskite interface modification layer is a reversible dynamic chemical bond, and local decrosslinking and re-crosslinking can occur when the borate crosslinking bond is stimulated by heat, so that macroscopic flow of materials such as polyvinyl alcohol and borax is realized. When the perovskite interface repairing layer is applied to a perovskite battery, cracks of a perovskite light absorption layer can be repaired, so that the physical integrity and compactness of the perovskite light absorption layer can be recovered, invasion channels of external harmful components such as water and oxygen are effectively cut off, and the long-term service life and the reliability of a device are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to perovskite interface modification layers, perovskite batteries and their preparation methods, and stacked batteries. Background Technology

[0002] Perovskite solar cells (PSCs), as outstanding representatives of third-generation photovoltaic technology, have shown great commercial potential due to their advantages such as high photoelectric conversion efficiency, low raw material cost, and simple fabrication process. However, insufficient long-term operational stability is the core bottleneck hindering the large-scale commercial application of perovskite solar cells. The performance degradation of these devices is caused by a combination of internal and external factors. External factors include humidity, oxygen, continuous light exposure, and high temperature in the environment. Among these, the synergistic effect of water and oxygen irreversibly decomposes the perovskite crystal structure, generating lead iodide (PbI2), which has inactive photoelectric properties.

[0003] Currently, the mainstream strategy for improving stability is external encapsulation, which involves sealing the device with materials such as epoxy resin and glass to prevent the intrusion of external water and oxygen. However, water and oxygen can still intrude into the perovskite light-absorbing layer, affecting the battery's power generation efficiency and even causing battery failure. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one objective of this invention is to provide a perovskite interface modification layer that can effectively repair cracks in the perovskite light-absorbing layer and prevent the intrusion of water and oxygen.

[0005] In one aspect of the invention, a perovskite interface modification layer is provided. According to an embodiment of the invention, the perovskite interface modification layer comprises polyvinyl alcohol and borax. The hydroxyl groups in the polyvinyl alcohol form dynamic borate ester crosslinks with the borate ions from the hydrolysis of the borax. These borate ester crosslinks break at a temperature greater than or equal to 40°C and rebuild at a temperature less than 40°C. Thus, the borate ester crosslinks in the perovskite interface modification layer are reversible dynamic chemical bonds. Consequently, the perovskite interface repair layer possesses a three-dimensional crosslinked network composed of dynamic reversible bonds. When this three-dimensional crosslinked network of the polymer is subjected to heat (such as heat generated during battery operation), it can undergo local decrosslinking, i.e., the breakage of the borate ester crosslinks. After the temperature drops, the borate ester crosslinks re-crosslink, thereby achieving macroscopic flow of materials such as polyvinyl alcohol and borax. When this perovskite interface repair layer is applied to a perovskite solar cell, it can be placed adjacent to the perovskite light-absorbing layer. If cracks occur in the perovskite light-absorbing layer, the decrosslinked polyvinyl alcohol and borax flow and fill the cracks, restoring the physical integrity and density of the perovskite light-absorbing layer. This effectively cuts off the intrusion channels of harmful components such as external water and oxygen, and can effectively alleviate the problem of stress concentration between the layer structures, thereby greatly improving the long-term service life and reliability of the device.

[0006] According to an embodiment of the present invention, the mass ratio of the polyvinyl alcohol to the borax is 1:(0.16~0.24).

[0007] According to an embodiment of the present invention, the thickness of the perovskite interface modification layer is 10 nm to 100 nm.

[0008] In another aspect, the present invention provides a perovskite solar cell. According to an embodiment of the present invention, the perovskite solar cell includes: a transparent conductive substrate; a first charge transport layer disposed on one side of the transparent conductive substrate; a perovskite interface modification layer disposed on the side of the first charge transport layer away from the transparent conductive substrate; a perovskite light-absorbing layer disposed on the surface of the perovskite interface modification layer away from the transparent conductive substrate; and a second charge transport layer disposed on the side of the perovskite light-absorbing layer away from the transparent conductive substrate. Thus, when cracks occur in the perovskite light-absorbing layer, the decrosslinked polyvinyl alcohol and borax in the perovskite interface modification layer flow and fill the cracks, restoring the physical integrity and density of the perovskite light-absorbing layer. This effectively cuts off the intrusion channels of harmful components such as external water and oxygen, and effectively alleviates the problem of stress concentration between layer structures, thereby greatly improving the long-term service life and reliability of the device.

[0009] According to an embodiment of the present invention, the perovskite light-absorbing layer has cracks, and a portion of the material of the perovskite interface modification layer fills the cracks.

[0010] In another aspect, the present invention provides a tandem solar cell. According to an embodiment of the invention, the tandem solar cell includes a perovskite top cell and a crystalline silicon bottom cell, wherein the perovskite top cell is the perovskite cell described above. Thus, the tandem solar cell has a long service life and high reliability.

[0011] In another aspect, the present invention provides a method for preparing the aforementioned perovskite solar cell. According to an embodiment of the present invention, the method for preparing the perovskite solar cell includes: forming a first charge transport layer on one side of a transparent conductive substrate; forming a polyvinyl alcohol (PVA) film on the side of the first charge transport layer away from the transparent conductive substrate based on a polyvinyl alcohol solution; dropping an aqueous borax solution onto the surface of the PVA film and spin-coating it to obtain a pre-modified layer; curing the pre-modified layer to obtain the perovskite interface modification layer; forming a perovskite light-absorbing layer on the surface of the perovskite interface modification layer away from the transparent conductive substrate; and forming a second charge transport layer on the side of the perovskite light-absorbing layer away from the transparent conductive substrate. Thus, when cracks occur in the perovskite light-absorbing layer, the decrosslinked PVA and borax in the perovskite interface modification layer flow and fill the cracks, restoring the physical integrity and density of the perovskite light-absorbing layer. This effectively cuts off the intrusion channels of harmful components such as external water and oxygen, and effectively alleviates the problem of stress concentration between layer structures, thereby greatly improving the long-term service life and reliability of the device.

[0012] According to an embodiment of the present invention, the mass concentration of the polyvinyl alcohol solution is 1~5wt%; and / or, the polyvinyl alcohol film is prepared by spin coating at a rotation speed of 3000-5000 rpm for 20-60 s.

[0013] According to an embodiment of the present invention, the mass concentration of the borax aqueous solution is 0.2~1wt%; and / or, before the curing, the added borax aqueous solution is spin-coated at a speed of 4000~6000rpm for 20~60s.

[0014] According to an embodiment of the present invention, the curing temperature is 50~80°C and the time is 3~10 minutes.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the structure of a perovskite solar cell in one embodiment of the present invention; Figure 2 This is a partial schematic diagram of repairing cracks in the perovskite light-absorbing layer in another embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a stacked battery in another embodiment of the present invention. Detailed Implementation

[0017] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0018] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0019] The inventors discovered that perovskite light-absorbing materials in perovskite solar cells possess an extremely high coefficient of thermal expansion (CTE), with a value of approximately 50 × 10⁻⁶. -6 K -1 It is much larger than its supporting substrate (such as FTO glass, approximately 10×10). -6 K -1 This significant CTE mismatch leads to the accumulation of substantial residual tensile stress within the perovskite light-absorbing layer during the cooling process from the high-temperature annealed state to room temperature, or during battery operation. This stress provides a strong intrinsic driving force for material fracture. During the service life of the perovskite solar cell, external stresses such as thermal cycling and vibration are superimposed on the internal residual stress. When the total stress exceeds the fracture toughness of the material, microcracks begin to form and propagate within the perovskite light-absorbing layer or at the interlayer interfaces.

[0020] However, these internally generated microcracks are not only physical damage, but also act as "highways" accelerating the intrusion of various external degradation factors. Microcracks disrupt the physical integrity of the film, providing a direct permeation channel for harmful substances such as water and oxygen to penetrate the core active layer, resulting in a chemical degradation rate that is much higher than the slow diffusion through the intact perovskite light-absorbing layer. Moreover, external encapsulation is powerless to prevent internal microcracks caused by inherent CTE mismatch and mechanical stress within the device.

[0021] Based on this, in one aspect of the present invention, a perovskite interface modification layer is provided. According to an embodiment of the present invention, the perovskite interface modification layer comprises polyvinyl alcohol (PVA) and borax. Dynamic borate ester crosslinking bonds are formed between the hydroxyl groups in the PVA and the borate ions from the hydrolysis of borax. These borate ester crosslinking bonds break at a temperature greater than or equal to 40°C and rebuild at a temperature less than 40°C. Thus, the borate ester crosslinking bonds in the perovskite interface modification layer are reversible dynamic chemical bonds. Consequently, the perovskite interface repair layer possesses a three-dimensional crosslinking network composed of dynamic and reversible bonds. When this three-dimensional crosslinking network of the polymer is subjected to heat (such as heat generated during battery operation), it can undergo local decrosslinking, i.e., the breakage of the borate ester crosslinking bonds. After the temperature drops, the borate ester crosslinking bonds re-crosslink, thereby achieving macroscopic flow of materials such as polyvinyl alcohol and borax. When this perovskite interface repair layer is applied to a perovskite solar cell, it can be placed adjacent to the perovskite light-absorbing layer. If the cell temperature rises (e.g., due to heat generated during operation), the perovskite light-absorbing layer will accumulate huge residual tensile stress due to CTE mismatch, leading to cracks inside the perovskite light-absorbing layer or at the interlayer interface. At the same time, the increased temperature also causes the borate ester crosslinking bonds to break, and the decrosslinked polyvinyl alcohol and borax flow and fill the cracks, restoring the physical integrity and density of the perovskite light-absorbing layer. This effectively cuts off the intrusion channels of harmful components such as water and oxygen from the outside, and can effectively alleviate the problem of stress concentration between the layer structures, slow down chemical degradation, and thus greatly improve the long-term service life and reliability of the device. At the same time, this interface repair layer will not have a significant adverse effect on the carrier transport between the charge transport layer and the perovskite light-absorbing layer.

[0022] According to some embodiments of the present invention, the mass ratio of polyvinyl alcohol to borax is 1:(0.16~0.24), for example, mass ratios of 1:0.16, 1:0.17, 1:0.18, 1:0.19, 1:0.20, 1:0.21, 1:0.22, 1:0.23, 1:0.2, etc. Therefore, the above ratios can ensure sufficient reaction between polyvinyl alcohol and borax.

[0023] According to some embodiments of the present invention, the thickness of the perovskite interface modification layer is 10 nm to 100 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc. Therefore, the thickness of the perovskite interface repair film is relatively thin, and its presence will not adversely affect the transport of charge carriers, thus not adversely affecting the performance of the perovskite solar cell. If the thickness of the perovskite interface modification layer is too thick, an excessively thick polyvinyl alcohol (PVA) film needs to be formed. Since PVA is an insulating material, a thick PVA film will severely hinder the effective transport of charge, leading to an increase in the series resistance of the device, and thus significantly reducing the photoelectric conversion efficiency and fill factor of the cell.

[0024] In another aspect, the present invention provides a perovskite solar cell. According to an embodiment of the invention, referring to... Figure 1 The perovskite solar cell includes: a transparent conductive substrate 10; a first charge transport layer 21 disposed on one side of the transparent conductive substrate 10; a perovskite interface modification layer 30, disposed on the side of the transparent conductive substrate 10 away from the first charge transport layer 40; a perovskite light-absorbing layer 40 disposed on the surface of the perovskite interface modification layer 30 away from the transparent conductive substrate 10; and a second charge transport layer 22 disposed on the side of the perovskite light-absorbing layer 40 away from the transparent conductive substrate 10. Therefore, if the battery temperature rises (e.g., due to heat generated during operation), the perovskite light-absorbing layer will accumulate huge residual tensile stress due to CTE mismatch, leading to cracks inside the perovskite light-absorbing layer or at the interlayer interface. At the same time, the increased temperature also causes the borate ester crosslinking bonds to break, and the decrosslinked polyvinyl alcohol and borax flow and fill the cracks, restoring the physical integrity and density of the perovskite light-absorbing layer. This effectively cuts off the intrusion channels of harmful components such as water and oxygen from the outside, and can effectively alleviate the problem of stress concentration between the layer structures, slow down chemical degradation, and thus greatly improve the long-term service life and reliability of the device. Meanwhile, this interface repair layer will not have a significant adverse effect on the carrier transport between the charge transport layer and the perovskite light-absorbing layer.

[0025] According to an embodiment of the present invention, the perovskite interface modification layer is further described as a flexible hydrogel layer, which can act as a nanoscale "buffer pad" to effectively alleviate the interfacial stress caused by CTE mismatch between the perovskite light-absorbing layer and the rigid transparent conductive substrate, thereby reducing the probability of microcrack formation from the source. In addition, the perovskite interface repair layer can improve the physical contact of the interface and reduce the defect state density, which can have a positive impact on the open circuit voltage and fill factor of the battery.

[0026] According to some embodiments of the present invention, with reference to Figure 2 When cracks appear in the perovskite light-absorbing layer, and the perovskite interface modification layer is stimulated by heat (temperature reaches 40 degrees Celsius or above), the borate ester crosslinking bonds in the perovskite interface modification layer break, achieving macroscopic fluidity of the perovskite interface modification layer material. Therefore, some of the perovskite interface modification layer material can flow into the crack, that is, some of the perovskite interface modification layer material fills the crack. After the battery temperature decreases, polyvinyl alcohol and boric acid re-crosslink, forming borate ester crosslinking bonds.

[0027] According to some embodiments of the present invention, one of the first charge transport layer and the second charge transport layer may be an electron transport layer and the other may be a hole transport layer.

[0028] In some embodiments, the material of the hole transport layer may include nickel oxide (NiO). x , 1≤x≤2), cuprous iodide (CuI), cuprous oxide (Cu2O), cuprous thiocyanate (CuSCN), 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), 2,2',7,7'-tetratetra(di-p-tolylamino)spiro-9,9'-difluorene (Spiro-TTB), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid (MeO-4PACz), (4-(3,6-dimethyl ... (4-(9H-carbazole-9-yl)butyl)phosphonic acid (Me-4PACz), (4-(3,6-dibromo-9H-carbazole-9-yl)butyl)phosphonic acid (Br-4PACz), (2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACz), (2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl)phosphonic acid (Me-2PACz), (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACz), (2-(3,6-dibromo-9H-carbazole-9-yl)ethyl)phosphonic acid (Br-2PACz), etc.

[0029] In some embodiments, the electron transport material of the electron transport layer includes, but is not limited to, tin oxide, fullerenes and their derivatives, imide compounds, quinone compounds, etc. Exemplarily, the imide compounds include at least one selected from phthalimide, succinimide, N-bromosuccinimide, glutarimide, or maleimide; exemplarily, the quinone compounds include at least one selected from benzoquinone, naphthoquinone, phenanthrenequinone, or anthraquinone; exemplarily, the fullerenes and their derivatives include fullerene C 60 Fullerene C 70 PCBM([6,6]-phenyl-C 61 methyl butyrate), [6,6]-phenyl C 71 Methyl butyrate (PC) 71 At least one of BM). Further, the electron transport layer can be a single-layer structure, or a double-layer or triple-layer structure. In some specific embodiments, the electron transport layer can be a C60 layer with a thickness of 5-20 nm and a tin oxide layer with a thickness of 15-20 nm. The tin oxide layer can protect the C60 in subsequent processes.

[0030] In some embodiments, the material structure of the perovskite light-absorbing layer can be ABX3, wherein A is a monovalent cation, including but not limited to one or a mixture of several monovalent cations selected from cesium (Cs), rubidium (Rb), methylamino (CH3NH3), and formamidinyl (CH2(NH2)2); B is a divalent cation, including but not limited to one or a mixture of several divalent cations selected from lead (Pb) and tin (Sn); and X is a monovalent anion, including but not limited to one or a mixture of several monovalent anions selected from iodine (I), bromine (Br), chloride (Cl), fluorine (F), and thiocyanate (SCN). In some specific embodiments, the material structure of the perovskite light-absorbing layer can be Cs. x FA 1-x Pb(I y Br 1-y 3, x and y are 0~1 respectively.

[0031] According to some embodiments of the present invention, the thickness of the perovskite light-absorbing layer is 500-700 nm.

[0032] According to an embodiment of the present invention, referring to Figure 1 The perovskite solar cell also includes a top transparent conductive layer 60 disposed on the side of the second charge transport layer away from the transparent conductive substrate.

[0033] In some embodiments, the materials of the transparent conductive substrate and the top transparent conductive layer include, but are not limited to, transparent conductive materials such as ITO and IZO.

[0034] In another aspect, the present invention provides a stacked battery. According to an embodiment of the present invention, referring to... Figure 3 The tandem solar cell includes a perovskite top cell and a crystalline silicon bottom cell 100, wherein the perovskite top cell is the perovskite cell described above. Therefore, the tandem solar cell has a long service life and high reliability.

[0035] According to some embodiments of the present invention, the specific structure and fabrication method of the crystalline silicon bottom cell are not particularly required, and those skilled in the art can flexibly choose according to actual needs. In some embodiments, the crystalline silicon bottom cell can be a TOPCON or BC cell, such as a TBC cell, an HBC cell, or a hybrid BC cell.

[0036] According to embodiments of the present invention, when the perovskite battery or tandem battery of the present invention is placed outdoors or in a high temperature and high humidity environment (such as 85°C, 85% RH), the photoelectric conversion efficiency (PCE) of the battery decreases by only 5%-15% after 1000 hours, and there is almost no significant performance degradation after 5000 hours of continuous operation. The performance retention rate is over 75%, the lifespan is greatly improved, and the long-term stability can reach 3-5 years or even longer in actual environments.

[0037] In another aspect, the present invention provides a method for preparing the aforementioned perovskite solar cell. According to an embodiment of the present invention, the method for preparing a perovskite solar cell includes: S100: A first charge transport layer is formed on one side of a transparent conductive substrate.

[0038] In some embodiments, if the perovskite solar cell is a perovskite top cell of a tandem solar cell, a crystalline silicon bottom cell is first prepared, then a transparent conductive layer substrate is formed on top of the crystalline silicon bottom cell, and then a first charge transport layer is formed on the other side of the transparent conductive layer substrate. There are no special requirements for the specific fabrication method of the crystalline silicon bottom cell; those skilled in the art can flexibly design it by combining the specific structure of the crystalline silicon bottom cell with existing fabrication processes.

[0039] According to some embodiments of the present invention, the first charge transport layer can be formed by methods such as coating or deposition.

[0040] S200: A polyvinyl alcohol film is formed on the side of the first charge transport layer away from the transparent conductive substrate based on a polyvinyl alcohol solution.

[0041] According to some embodiments of the present invention, the mass concentration of the polyvinyl alcohol solution is 1 to 5 wt%, such as 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, etc. This allows for the formation of a relatively dense and uniformly distributed polyvinyl alcohol (PVA) film. However, if the mass concentration is too low, the continuity of the PVA film is relatively poor, which is not conducive to forming a dense and uniformly distributed film, and may affect its ability to repair cracks in the perovskite light-absorbing layer. If the mass concentration is too high, on the one hand, an excessively thick PVA insulating layer will be formed, which will severely hinder the effective transfer of charge, leading to an increase in the series resistance of the device, and thus significantly reducing the photoelectric conversion efficiency and fill factor of the battery. On the other hand, the viscosity of a high-concentration PVA solution is relatively high, making it difficult to spread evenly during coating (such as spin coating), which may result in uneven PVA film thickness. Furthermore, during subsequent curing, a thicker coating is difficult to dry completely, which can easily cause solvent residue. The residual solvent may affect the stability of the perovskite light-absorbing layer during long-term battery operation.

[0042] According to some embodiments of the present invention, the polyvinyl alcohol film is prepared by spin coating at a rotation speed of 3000-5000 rpm, such as 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm, etc., and for a time of 20-60 s, such as 20 s, 30 s, 40 s, 50 s, 60 s, etc. Under the above conditions, the polyvinyl alcohol solution can be uniformly distributed, resulting in a continuous and uniform polyvinyl alcohol film.

[0043] S300: A borax aqueous solution is dropped onto the surface of a polyvinyl alcohol film and then spin-coated to obtain a pre-modified layer.

[0044] According to some embodiments of the present invention, the mass concentration of the borax aqueous solution is 0.2~1 wt%, such as 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, etc. This allows the borax to react fully with the polyvinyl alcohol.

[0045] In some embodiments, an excess of borax aqueous solution may be added dropwise to ensure a complete reaction between borax and polyvinyl alcohol.

[0046] According to some embodiments of the present invention, before curing, i.e., after adding the borax aqueous solution and allowing it to stand for a few seconds, the added borax aqueous solution is spin-coated at a speed of 4000~6000 rpm, such as 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm, 6000 rpm, etc., for a time of 20~60 s, such as 20 s, 30 s, 40 s, 50 s, 60 s, etc. Under the above conditions, excess liquid can be removed, and the borax and polyvinyl alcohol can be fully contacted to carry out an in-situ crosslinking reaction, that is, the hydroxyl groups in polyvinyl alcohol react with the borate ions from the hydrolysis of borax to form reversible borate ester crosslinking bonds.

[0047] S400: The pre-modified layer is cured to obtain a perovskite interface modified layer. During the curing process, the hydroxyl groups in polyvinyl alcohol and the borate ions from borax hydrolysis undergo a full cross-linking reaction to form a stable network structure.

[0048] According to some embodiments of the present invention, the curing temperature is 50~80°C, such as 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, etc., and the curing time is 3~10 minutes, such as 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc. Therefore, under the above conditions, both the hydroxyl groups in polyvinyl alcohol and the borate ions from borax hydrolysis can undergo a sufficient cross-linking reaction, residual moisture can be removed, and the network structure formed by the cross-linking reaction can be stabilized.

[0049] S500: A perovskite light-absorbing layer is formed on the surface of the perovskite interface modification layer away from the transparent conductive substrate.

[0050] In some embodiments, there are no special requirements for the method of preparing the perovskite light-absorbing layer. Those skilled in the art can make flexible choices according to actual needs, such as preparing it by solution method, vapor deposition method or inkjet printing method.

[0051] S600: A second charge transport layer is formed on the side of the perovskite light-absorbing layer away from the transparent conductive substrate.

[0052] According to some embodiments of the present invention, the first charge transport layer can be formed by methods such as coating or deposition.

[0053] According to some embodiments of the present invention, the method for preparing perovskite solar cells further includes forming a top transparent conductive layer, for example, by evaporation deposition.

[0054] In some embodiments, the materials of the transparent conductive substrate and the top transparent conductive layer include, but are not limited to, transparent conductive materials such as ITO and IZO.

[0055] According to embodiments of the present invention, if the battery temperature rises (e.g., due to heat generated during operation), the perovskite light-absorbing layer accumulates significant residual tensile stress due to CTE mismatch, leading to cracks within the perovskite light-absorbing layer or at the interlayer interface. Simultaneously, the increased temperature causes the borate ester crosslinking bonds to break, achieving macroscopic fluidity of the perovskite interface modification layer material. Therefore, some material from the perovskite interface modification layer can flow into the cracks, filling them and restoring the physical integrity and density of the perovskite light-absorbing layer. This effectively cuts off the intrusion channels of harmful components such as external water and oxygen, and effectively alleviates the stress concentration problem between layer structures. Furthermore, after the battery temperature decreases, polyvinyl alcohol and boric acid re-crosslink, forming borate ester crosslinking bonds. Thus, by actively suppressing the generation and propagation of microcracks within the battery, the stability of the perovskite battery under harsh operating conditions such as humid heat and high / low temperature cycling is greatly improved, enhancing the long-term service life and reliability of the device.

[0056] Furthermore, the above-mentioned method for preparing the perovskite interface repair layer is highly compatible with the fabrication processes of tandem solar cells and perovskite solar cells. It does not require the introduction of complex equipment, but only requires the addition of a simple solution method to prepare the repair layer, which has the advantages of low cost and easy integration for industrialization.

[0057] Example Example 1 Methods for preparing tandem solar cells include: The fabrication method for TOPCON bottom cells includes: The original silicon wafer is polished. The polishing alkaline solution is composed of NaOH and polishing additives in a volume ratio of 11:3, with a NaOH concentration of 2.1%. The solution temperature is 67℃ and the process time is 280s to remove the mechanical damage layer on the surface of the original silicon wafer. A first tunneling layer and a first polycrystalline silicon layer with a thickness of 2.2 nm were sequentially deposited on the back side of a silicon wafer using LPCVD deposition. The deposition conditions for the first tunneling layer were: oxygen flow rate of 31000 sccm, temperature of 605℃, process time of 1200 s, and tube blocking for 600 s. The deposition conditions for the first polycrystalline silicon layer were: deposition temperature of 555℃, process time of 11500 s, and silane flow rates of 190 sccm, 440 sccm, and 620 sccm for the three gas inlet methods, respectively. Boron-doped polysilicon layer is subjected to the following process: boron trichloride is passed through a boron source with a flow rate of 250 sccm, a temperature of 860℃, and a process time of 1100 s; the advance step temperature is 950℃, and the process time is 1100 s; the oxidation temperature is 950℃, the oxygen flow rate is 8500 sccm, and the oxidation time is 1650 s, ultimately forming a boron-doped polysilicon layer + borosilicate glass (BSG) structure. The boron-doped polysilicon layer and the n-type substrate silicon wafer form a PN junction. The thickness of the BSG is 50 nm, the sheet resistance of the boron-doped polysilicon layer is 80, and the thickness is 320 nm. The BSG formed on the front and sides is removed by a wet chain machine (HF solution); The process involves flocking and rounding using a wet trough mill to remove P-poly from the front and sides. The wet trough mill's flocking tank has a temperature of 60℃ and a processing time of 550s. The alkaline solution used for flocking consists of H2O, NaOH, and flocking additives in a volume ratio of 1000:200:13. The wet trough mill's rounding tank has a temperature of 60℃ and a processing time of 100s. The alkaline solution used for rounding consists of H2O, NaOH, and rounding additives in a volume ratio of 1000:3:6. A second tunneling layer and a second polycrystalline silicon layer with a thickness of 2.1 nm were sequentially deposited on the front side of a silicon wafer using LPCVD deposition. The deposition conditions for the second tunneling layer were: oxygen flow rate of 32000 sccm, temperature of 600℃, process time of 1200 s, and tube blocking for 600 s. The deposition conditions for the second polycrystalline silicon layer were: deposition temperature of 600℃, process time of 3000 s, and silane flow rates of 190 sccm, 440 sccm, and 620 sccm for the three gas inlet methods, respectively. Phosphorus diffusion was performed on the second polycrystalline silicon layer: phosphorus pentachloride was used as the phosphorus source, with a flow rate of 1250 sccm, a temperature of 810℃, and a process time of 1100 s; the advance step temperature was 875℃, and the process time was 1150 s; the oxidation temperature was 870℃, the oxygen flow rate was 2300 sccm, and the oxidation time was 800 s, ultimately forming a phosphorus-doped polycrystalline silicon layer + phosphosilicate glass (PSG) structure, wherein the surface concentration of the boron-doped polycrystalline silicon layer was 5.7 × 10^20 cm^-3. -3 The PSG thickness is 50nm, and the sheet resistance of the phosphorus-doped polycrystalline silicon layer is 20, with a thickness of 230nm. The PSG formed by the back and sides is removed by a wet chain machine; The poly coating deposited on the back side and the PSG on the front side are removed by a wet alkaline bath and an acid bath. The alkaline polishing bath temperature is 60℃, the process time is 300s, and the alkaline solution is composed of H2O, NaOH and polishing additives in a volume ratio of 300:18:5, with the NaOH concentration being approximately 3%. The acid bath temperature is 40℃, the process time is 120s, and the acid solution is composed of H2O and HF in a volume ratio of 3:2. An aluminum oxide passivation layer was deposited using the ALD deposition method with a back-to-back double insertion method. The ALD process temperature was 300℃, the process time was 900s, and the thickness of the passivation layer was 4.3nm. An antireflective coating is deposited at a temperature of 530℃. The coating consists of three layers, deposited in the order of silicon nitride 1, silicon nitride 2, and silicon nitride 3 in the direction away from the silicon wafer. The thicknesses of the three layers are 28nm, 29nm, and 30nm, respectively, with a final overall film thickness of 87nm and a refractive index of 2.12. Silver metal grid lines, i.e. back electrodes, are formed on the back side by screen printing. The metal and boron-doped polycrystalline silicon layer are sintered at high temperature to form ohmic contacts, collect current and conduct it out. The peak sintering temperature is 720℃, thus obtaining a crystalline silicon bottom cell.

[0058] A transparent conductive substrate ITO layer is deposited by vapor deposition on the front side of a crystalline silicon bottom cell; SnO2 colloidal solution was spin-coated onto the surface of the ITO layer and annealed at 150°C for 30 minutes to obtain an electron transport layer. A 2 wt% polyvinyl alcohol solution was dropped onto the surface of the electron transport layer and then spin-coated to form a polyvinyl alcohol film. The spin-coating speed was 4000 rpm and the time was 30 s. An excess of 0.5wt% borax aqueous solution was dropped onto the surface of a polyvinyl alcohol film. After standing for 5 seconds, the film was spin-coated at 5000 rpm for 30 seconds to obtain a pre-modified layer. The pre-modified layer was annealed at 65°C for 7 minutes to obtain a perovskite interface modification layer with a thickness of 45 nm. A perovskite precursor solution was spin-coated onto the surface of the perovskite interface modification layer away from the transparent conductive substrate to form a perovskite light-absorbing layer Cs with a thickness of 520 nm. 0.1 FA 0.9 Pb(I 0.9 Br 0.1 )3; Spiro-OMeTAD solution was spin-coated onto the surface of the perovskite light-absorbing layer and then annealed to form a hole transport layer. A top transparent conductive layer (IZO) is formed on the surface of the hole transport layer; Finally, a metallic silver electrode is formed by thermal evaporation deposition to obtain a tandem battery.

[0059] Comparative Example 1 The method for preparing the tandem solar cell is basically the same as in Example 1, except that the method for preparing the perovskite top solar cell does not include the step of preparing the perovskite interface modification layer. The specific method for preparing the perovskite top solar cell includes: A transparent conductive substrate ITO layer is deposited by vapor deposition on the front side of a crystalline silicon bottom cell; SnO2 colloidal solution was spin-coated onto the surface of the ITO layer and annealed at 150°C for 30 minutes to obtain an electron transport layer. A perovskite precursor solution was spin-coated onto the surface of the electron transport layer away from the transparent conductive substrate to form a perovskite light-absorbing layer Cs with a thickness of 520 nm. 0.1 FA 0.9 Pb(I 0.9 Br 0.1 )3; Spiro-OMeTAD solution was spin-coated onto the surface of the perovskite light-absorbing layer and then annealed to form a hole transport layer. A top transparent conductive layer (IZO) is formed on the surface of the hole transport layer; Finally, a metallic silver electrode is formed by thermal evaporation deposition to obtain a tandem battery.

[0060] The performance degradation data of the tandem cells in Example 1 and Comparative Example 1 were tested. The tandem cells in Example 1 and Comparative Example 1 were placed in a high temperature and high humidity environment (85°C, 85% RH). The photoelectric conversion efficiency (PCE) of the two cells was tested before the test and after 1000 hours and 3000 hours of testing. The degradation rate of the photoelectric conversion efficiency and the PCE retention rate of the cells were calculated (PCE degradation rate + PCE retention rate = 100%), and the lifespan of the cells was predicted, as shown in Table 1.

[0061] Table 1

[0062] Therefore, due to the setting of the perovskite interface repair layer, the intrusion of water and oxygen can be better prevented, and the damage of water and oxygen to the active material of the light-absorbing layer can be avoided, so that the perovskite battery and the stacked battery of the present invention can have a more stable long service life.

[0063] The terms "first" and "second" used in this document are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature marked "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0064] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0065] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A perovskite interface modification layer, characterized in that, The mixture includes polyvinyl alcohol and borax, wherein the hydroxyl groups in the polyvinyl alcohol form dynamic borate ester crosslinks with the borate ions from the hydrolysis of the borax, and the borate ester crosslinks break at a temperature greater than or equal to 40°C and are rebuilt at a temperature less than 40°C.

2. The perovskite interface modification layer according to claim 1, characterized in that, The mass ratio of the polyvinyl alcohol to the borax is 1:(0.16~0.24).

3. The perovskite interface modification layer according to claim 1 or 2, characterized in that, The thickness of the perovskite interface modification layer is 10 nm to 100 nm.

4. A perovskite battery, characterized in that, include: Transparent conductive substrate; A first charge transport layer is disposed on one side of the transparent conductive substrate; The perovskite interface modification layer according to any one of claims 1 to 3, wherein the perovskite interface modification layer is disposed on the side of the first charge transport layer away from the transparent conductive substrate; A perovskite light-absorbing layer is disposed on the surface of the perovskite interface modification layer away from the transparent conductive substrate; A second charge transport layer is disposed on the side of the perovskite light-absorbing layer away from the transparent conductive substrate.

5. The perovskite solar cell according to claim 4, characterized in that, The perovskite light-absorbing layer has cracks, and part of the material of the perovskite interface modification layer fills the cracks.

6. A stacked battery, characterized in that, It includes perovskite top cells and crystalline silicon bottom cells, wherein the perovskite top cell is the perovskite cell described in claim 4 or 5.

7. A method for preparing the perovskite solar cell according to claim 4 or 5, characterized in that, include: A first charge transport layer is formed on one side of a transparent conductive substrate; A polyvinyl alcohol film is formed on the side of the first charge transport layer away from the transparent conductive substrate based on a polyvinyl alcohol solution; A borax aqueous solution was dropped onto the surface of the polyvinyl alcohol film and then spin-coated to obtain a pre-modified layer; The pre-modified layer is cured to obtain the perovskite interface modified layer; A perovskite light-absorbing layer is formed on the surface of the perovskite interface modification layer away from the transparent conductive substrate; A second charge transport layer is formed on the side of the perovskite light-absorbing layer away from the transparent conductive substrate.

8. The method according to claim 7, characterized in that, The polyvinyl alcohol solution has a mass concentration of 1-5 wt%. And / or, the polyvinyl alcohol film is prepared by spin coating at a speed of 3000-5000 rpm for 20-60 s.

9. The method according to claim 7 or 8, characterized in that, The mass concentration of the borax aqueous solution is 0.2~1wt%; And / or, prior to the curing, spin-coating the added borax aqueous solution at a speed of 4000~6000 rpm for 20~60 s.

10. The method according to claim 7 or 8, characterized in that, The curing temperature is 50~80°C, and the time is 3~10 minutes.

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