Tannic acid biomimetic modified perovskite solar cell and preparation method thereof
By coordinating tannic acid with tin dioxide, an integrated system of dual coordination, interface bonding, and defect passivation was constructed, which solved the problem of interface defects in perovskite solar cells, improved photoelectric conversion performance and stability, and realized the fabrication of efficient and stable perovskite solar cells.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-27
AI Technical Summary
In existing perovskite solar cells, surface defects in the tin dioxide electron transport layer and interface defects in the perovskite thin film lead to photogenerated carrier recombination centers, affecting the photoelectric conversion efficiency and long-term stability of the device.
By employing a biomimetic modification method using tannic acid, an integrated system of dual coordination, interface adhesion, and defect passivation is constructed through the coordination interaction between tannic acid and tin dioxide. This improves the interfacial bonding between the electron transport layer and the perovskite layer, and reduces interface defects and photogenerated carrier recombination.
It significantly improves carrier transport efficiency, enhances the light absorption capacity and crystallinity of perovskite crystals, improves the environmental stability and long-term lifespan of devices, and reduces fabrication costs and environmental burden.
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Figure CN121751875A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a tannic acid biomimetic modified perovskite solar cell and its preparation method, belonging to the field of perovskite solar cells. Background Technology
[0002] In recent years, perovskite solar cells (PSCs) have become an important complementary technology to silicon-based solar cells due to their rapid development in photoelectric conversion efficiency (certified to exceed 27%) and low cost, demonstrating broad prospects for commercial application. Their core working principle is as follows: under illumination, the perovskite light-absorbing layer generates excitons; after exciton separation, electrons and holes migrate to the transport layers at both ends of the device, ultimately achieving photoelectric conversion. Although significant progress has been made in device performance, poor environmental stability and short lifespan remain the core bottlenecks restricting their large-scale practical application.
[0003] The electron transport layer, as a key functional layer in perovskite solar cells, directly affects carrier transport efficiency and interface stability. Tin dioxide (SnO2) is widely recognized as the preferred material for the electron transport layer in high-efficiency perovskite solar cells due to its high conductivity, low photocatalytic activity, and wide bandgap. However, tin dioxide films prepared by spin-coating in existing technologies have inherent defects: intrinsic defects such as oxygen vacancies easily form on the surface. These defects become recombination centers for photogenerated carriers and accelerate the penetration of external factors such as water and oxygen into the perovskite layer, severely degrading the photoelectric conversion performance and long-term stability of the device. Commercial tin dioxide colloidal precursors often use potassium hydroxide as a stabilizer. This substance introduces hydroxyl groups into the surface of the prepared tin dioxide film, making it weakly alkaline, which in turn disrupts the crystal structure of the overlying perovskite layer and adversely affects the long-term storage stability of tin dioxide aqueous dispersions.
[0004] Furthermore, in the two-step fabrication process of perovskite thin films, a lead iodide (PbI2) precursor film is typically first deposited on the surface of the electron transport layer by spin-coating, followed by spin-coating of organic amine salt solutions such as methylamine iodine and formamidinium iodine onto its surface. The two react at the solid-liquid interface to form perovskite crystals. Because this conversion reaction begins on the surface of the PbI2 film and gradually progresses inward, the underlying PbI2 has difficulty fully contacting and reacting with the organic amine salts, resulting in a large amount of PbI2 residue at the bottom interface. Simultaneously, the rapid crystallization of the upper perovskite crystal generates outward compressive stress, further compressing the incompletely reacted bottom interface region. Ultimately, this leads to the formation of numerous physical voids and unreacted PbI2 impurities at the buried interface of the perovskite film. These defects not only disrupt the continuity of the interface but also become recombination centers for photogenerated carriers, significantly hindering the growth of high-quality perovskite crystals and severely affecting the photoelectric conversion efficiency and long-term stability of the device.
[0005] Therefore, defect control, interface optimization, and crystal quality control of the tin dioxide electron transport layer have become key technical requirements for the fabrication of high-efficiency and stable perovskite solar cells. Summary of the Invention
[0006] To address the problems existing in the prior art, this invention provides a tannic acid biomimetic modified perovskite solar cell and its preparation method, which effectively improves carrier migration rate, reduces interface defects and barriers, and improves the light absorption capacity and crystallinity of perovskite crystals.
[0007] To achieve the above objectives, the present invention employs a tannic acid biomimetic modified perovskite solar cell, which comprises, from bottom to top: a conductive substrate, a tannic acid-tin dioxide composite electron transport layer, a tannic acid biomimetic interface layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode.
[0008] The tannic acid-tin dioxide composite electron transport layer is prepared by spin coating and annealing after mixing tannic acid and tin dioxide in a solution, and tannic acid and tin dioxide form a coordination effect; the tannic acid biomimetic interface layer achieves interface adhesion and defect passivation through the coordination effect of tannic acid molecules with tin dioxide and perovskite.
[0009] A second aspect of the present invention also provides a method for preparing a tannic acid biomimetic modified perovskite solar cell, comprising the following steps:
[0010] S1. Clean the conductive substrate and set aside.
[0011] S2. Preparation of tannic acid-tin dioxide composite electron transport layer and tannic acid biomimetic interface layer
[0012] S2-1. Dissolve tannic acid powder evenly in deionized water (preferably with a resistivity ≥18.2 MΩ·cm) to prepare tannic acid stock solution;
[0013] S2-2. The tin dioxide stock solution is diluted with deionized water and then mixed with the tannic acid stock solution in step S2-1 to obtain a tannic acid-tin dioxide composite solution. The composite solution is spin-coated onto the surface of a conductive substrate and annealed to obtain a tannic acid-tin dioxide composite electron transport layer.
[0014] S2-3. The tannic acid stock solution from step S2-1 is mixed and diluted with deionized water, and then spin-coated onto the surface of the tannic acid-tin dioxide composite electron transport layer from step S2-2. After annealing, a tannic acid biomimetic interface layer is obtained.
[0015] S3. Prepare a perovskite light-absorbing layer on a tannic acid biomimetic interface layer;
[0016] S4. Deposit a hole transport layer on the perovskite light-absorbing layer;
[0017] S5. Deposit metal electrodes on the hole transport layer.
[0018] As an improvement, in step S2-1, the concentration of the tannic acid stock solution is 5-6 mg / mL.
[0019] As an improvement, in step S2-2, the volume ratio of tin dioxide stock solution to deionized water is 1:(4-5); and / or, the volume ratio of tannic acid stock solution to diluted tin dioxide solution is 1:(2-11). The TA concentration needs to be controlled within the above range. If the TA concentration further increases, it will lead to an abnormal decrease in the conductivity of the TA-tin dioxide film, which is detrimental to the subsequent directional transport of charge carriers, thus affecting the overall photoelectric performance of the device. Furthermore, the spin-coating speed is 3000 rpm, the time is 30 seconds, and the acceleration is 1000-3000 rpm. 2 .
[0020] As an improvement, in step S2-2, the spin coating environment is an air atmosphere with a humidity of 30-60%; and / or, the annealing temperature is 130-150℃ and the time is 20-30 minutes.
[0021] As an improvement, in steps S2-3, the volume ratio of tannic acid stock solution to deionized water is 1:(2-5); and / or, the spin-coating environment is an air atmosphere with a humidity of 30-60%; and / or, the annealing temperature is 100-150℃, and the time is 5-10 minutes. The spin-coating speed is 5000 rpm, the time is 20 seconds, and the acceleration is 5000-9999 rpm. 2 .
[0022] As an improvement, in step S1, the conductive substrate is ITO conductive glass or FTO conductive glass; the cleaning process includes sequential ultrasonic cleaning with cleaning solution, deionized water, and isopropanol, followed by nitrogen drying.
[0023] As an improvement, in step S3, the perovskite light-absorbing layer is prepared using a two-step method in a nitrogen atmosphere. Further, a lead iodide solution is prepared using a DMF / DMSO mixed solvent with a volume ratio of 9:1, and an organic cationic solution containing formamidine and methylamine chloride is prepared using isopropanol as a solvent. The perovskite light-absorbing layer is then formed in situ on the tannic acid biomimetic interface layer using a two-step sequential deposition method. The spin-coating time for the lead iodide solution is 30 seconds, the annealing temperature is 70°C, and the time is 50-70 seconds; the spin-coating time for the formamidine solution is 30 seconds, the annealing temperature is 140-150°C, and the time is 10-15 minutes.
[0024] As an improvement, in step S4, the hole transport layer material is Spiro-OMeTAD. The preparation of the Spiro-OMeTAD solution includes dissolving Spiro-OMeTAD in chlorobenzene and adding a lithium bis(trifluoromethane)sulfonamide solution and a 4-tert-butylpyridine solution. The spin-coating time of the Spiro-OMeTAD solution is 20-30 seconds; it is then placed in a drying cabinet for oxidation for 12-24 hours to form a stable hole transport layer.
[0025] As an improvement, in step S5, the metal electrode is silver or gold; it is prepared by vapor deposition, and after vapor deposition, it can be further placed in a drying cabinet to improve the interfacial bonding stability.
[0026] Core mechanism of action:
[0027] This invention draws inspiration from the adhesion mechanism of aphid legs, utilizing the abundant hydroxyl functional groups in the tannic acid (TA) molecule to construct an integrated system of dual coordination, interfacial adhesion, and defect passivation: The TA molecule first undergoes a coordination reaction with the tetravalent tin ions of tin dioxide in the tannic acid-tin dioxide composite electron transport layer through its hydroxyl groups, forming a stable polynuclear complex, thereby passivating the intrinsic defects of oxygen vacancies on the tin dioxide layer surface; simultaneously, TA… The uncoordinated hydroxyl groups further coordinate with lead ions at the perovskite light-absorbing layer's buried interface, firmly bonding the composite electron transport layer to the perovskite light-absorbing layer through dual coordination. This effectively eliminates interfacial voids and barriers, simultaneously passivating defects at the perovskite layer's buried interface. Furthermore, the large molecular structure and multiple coordination sites of TA can loosen the dense lead iodide film, forming nanochannels that provide an efficient pathway for the penetration and diffusion of organic amine salt solutions. This promotes a thorough solid-liquid reaction between the organic amine salt and the underlying PbI2, significantly reducing PbI2 residue at the perovskite bottom interface during the two-step preparation process. Ultimately, this yields high-quality perovskite crystals with high crystallinity and low defect density. This biomimetic interface modification strategy fundamentally reduces recombination losses of photogenerated carriers at the interface, improves carrier transport efficiency, and simultaneously blocks the penetration of external factors such as water and oxygen, providing a core guarantee for the high performance and long-term stability of perovskite solar cells.
[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0029] 1. This invention is the first to simultaneously introduce tannic acid (TA) into the tin dioxide electron transport layer and the perovskite buried interface. Innovatively drawing inspiration from the adhesion mechanism of aphid legs, it utilizes the multiple interactions between the abundant hydroxyl groups in the TA molecule and tetravalent tin ions, as well as lead ions in the perovskite, to construct an integrated buried interface structure with strong interfacial adhesion and dual defect passivation. This design overcomes the limitations of traditional interface modification techniques that only focus on a single function (such as simple defect passivation or interface adhesion). It effectively eliminates the intrinsic defects of oxygen vacancies in the tin dioxide layer and defects in the perovskite buried interface, reducing recombination losses of photogenerated carriers. Furthermore, it strengthens the interfacial bonding strength between the electron transport layer and the perovskite layer, lowers the interfacial barrier, and significantly improves carrier transport efficiency, achieving a leapfrog improvement in the device's photoelectric conversion performance.
[0030] 2. The integrated buried interface formed by the multiple coordination interactions of TA molecules effectively blocks the penetration of external environmental factors such as water and oxygen into the perovskite layer, and inhibits the damage to the perovskite crystal structure caused by the weak alkalinity of the tin dioxide layer surface. Simultaneously, TA promotes the full reaction between organic amine salts and lead iodide, reducing lead iodide residue at the perovskite bottom interface prepared by the two-step method, thereby obtaining high-quality crystals. This significantly improves the environmental stability and long-term operating life of the device, solving the core bottleneck of insufficient stability in the practical application of existing perovskite solar cells, and further promoting its commercialization.
[0031] 3. As a natural extract, TA is widely available and environmentally friendly. Its aqueous solution system is mild and requires no complex synthesis process, avoiding the toxicity, corrosiveness, or cumbersome synthesis processes associated with traditional interface modifiers. Furthermore, the spin-coating and annealing processes employed in this invention are mature, low-cost technologies in the perovskite solar cell field, highly compatible with existing industrial production equipment. This not only reduces the environmental burden and cost of device fabrication but also provides a feasible path for the large-scale, green production of high-performance perovskite solar cells. Attached Figure Description
[0032] Figure 1 The image shows a transmission electron microscope (TEM) comparison between the TA-tin dioxide composite electron transport layer in Example 1 and the unmodified tin dioxide layer in Comparative Example 1.
[0033] Figure 2 This is a graph showing the conductivity variation trend of TA-tin dioxide composite electron transport layers with different TA concentrations in Example 1;
[0034] Figure 3 A comparison chart of pH values for tin dioxide solution, TA solution, and TA-tin dioxide composite solution;
[0035] Figure 4Scanning electron microscope (SEM) images of the buried surfaces of perovskite films prepared in Example 2 (TA-tin dioxide / TA biomimetic interface) and Comparative Example 2 (unmodified tin dioxide interface);
[0036] Figure 5 The photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra of the perovskite thin films prepared in Example 2 and Comparative Example 2 are shown.
[0037] Figure 6 This is a SEM cross-sectional view of the perovskite solar cell fabricated based on the TA biomimetic interface in Example 3;
[0038] Figure 7 The electrochemical impedance spectroscopy (EIS) fitting diagrams are shown for the perovskite solar cells prepared in Example 3 (TA-tin dioxide / TA biomimetic interface) and Comparative Example 3 (unmodified tin dioxide interface).
[0039] Figure 8 A comparison of the photoelectric conversion performance of perovskite solar cells with a biomimetic TA interface and conventional devices without TA. Detailed Implementation
[0040] The following embodiments are further illustrations of the present invention and serve as explanations of the technical content of the present invention. However, the essence of the present invention is not limited to the embodiments described below. Those skilled in the art can and should know that any simple changes or substitutions based on the spirit of the present invention should fall within the protection scope claimed by the present invention.
[0041] Example 1
[0042] The method for preparing a TA-tin dioxide composite electron transport layer specifically includes the following steps:
[0043] (1) Substrate cleaning: Take an ITO conductive glass with a size of 2cm×2cm, and clean it with cleaning solution, deionized water and isopropanol in sequence for 15 minutes each. After cleaning, blow it dry with a nitrogen air gun and set it aside.
[0044] (2) Solution preparation: Weigh 12 mg of TA powder, add 2 mL of deionized water, and shake on a shaker for 10 minutes until completely dissolved to obtain a TA stock solution with a concentration of 6 mg / mL; take 500 μL of tin dioxide stock solution, add 2 mL of deionized water to dilute it to obtain a diluted tin dioxide solution; mix the TA stock solution and the above diluted tin dioxide solution at a volume ratio of 1:5 to prepare a TA-tin dioxide composite solution with a concentration of 1 mg / mL;
[0045] (3) Preparation of TA-tin dioxide composite electron transport layer: The cleaned substrate (ITO conductive glass) was placed in an ultraviolet ozone generator for 15 minutes. After the substrate cooled down, 100 μL of TA-tin dioxide composite solution was dropped onto the substrate surface under an ambient humidity of 50%. The substrate was spin-coated at 3000 rpm for 30 seconds, and then heated and annealed at 150°C for 30 minutes to obtain the TA-tin dioxide composite electron transport layer.
[0046] Comparative Example 1
[0047] The preparation process is largely the same as in Example 1, except that:
[0048] In step (2), no TA stock solution is added. Instead, 500 μL of tin dioxide stock solution is diluted with 2 mL of deionized water and treated with the same spin coating and annealing parameters as in Example 1 to obtain an unmodified tin dioxide electron transport layer.
[0049] The TA-tin dioxide composite layer of Example 1 and the unmodified tin dioxide layer of Comparative Example 1 were analyzed by transmission electron microscopy (TEM), and the results are shown in Figure 1. The lattice parameters of the two electron transport layers can be clearly observed from the figure. The interplanar spacing of the principal crystal plane (110) of both is 0.33 nm, indicating that the introduction of TA did not change the original lattice orientation of tin dioxide.
[0050] The TA-tin dioxide composite solutions with different TA doping concentrations in Example 1 (TA doping concentration 1 mg / mL) and the tin dioxide solution in Comparative Example 1 (TA doping concentration 0 mg / mL) were spin-coated into films and deposited with silver electrodes using the same method. The conductivity was then tested, and the results are shown in Figure 2. As can be seen from the figure, the TA-tin dioxide sample with a concentration of 1 mg / mL exhibits a larger slope and higher conductivity, indicating that the formation of a complex between TA and tin dioxide can significantly improve electron mobility and increase carrier density.
[0051] The pH values of the tin dioxide solution diluted with deionized water, the TA solution, and the TA-tin dioxide composite solution were tested, and the results are shown in Figure 3. The tests showed that the tin dioxide solution diluted with deionized water was strongly alkaline, the TA solution was weakly acidic, and the TA-tin dioxide composite solution obtained by mixing the two was neutral. This effectively avoided the adverse effects of adding potassium hydroxide stabilizer to the tin dioxide dispersion and improved the stability of the solution.
[0052] Example 2
[0053] A method for preparing a TA biomimetic interface layer and a TA biomimetic modified perovskite thin film includes the following steps:
[0054] (1) Substrate pretreatment: Substrate cleaning and preparation of TA-tin dioxide composite electron transport layer are completely consistent with the steps in Example 1;
[0055] (2) Preparation of TA solution: Weigh 6 mg of TA powder, add 1 mL of deionized water, place on a shaker and shake for 10 minutes until completely dissolved to obtain a TA stock solution with a concentration of 6 mg / mL; take 100 μL of the above TA stock solution, add 500 μL of deionized water to dilute to obtain a TA solution with a concentration of 1 mg / mL.
[0056] (3) Preparation of TA biomimetic interface layer: Take 50 μL of the diluted TA solution in step (2) and drop it onto the surface of the TA-tin dioxide composite electron transport layer. Spin coat it dynamically at 5000 rpm for 20 seconds, and then anneal it at 100℃ for 10 minutes to obtain the TA biomimetic interface layer.
[0057] (4) Preparation of perovskite light-absorbing layer: 691.5 mg of PbI2 was weighed and added to 1 mL of DMF / DMSO mixed solvent with a volume ratio of 9:1 to prepare a PbI2 precursor solution; under a nitrogen atmosphere, the solution was spin-coated onto the surface of the TA biomimetic interface layer at a speed of 1500 rpm for 30 seconds, and then annealed at 70 °C for 60 seconds; 180 mg of formamidine iodide (FAI) and 16 mg of methylamine chloride (MACl) were weighed and added to 1 mL of isopropanol to prepare an organic cation precursor solution; the solution was spin-coated onto the surface of the above PbI2 film at a speed of 1500 rpm for 30 seconds, and then annealed at 145 °C for 13 minutes in an air atmosphere (humidity 35%) to form a perovskite film.
[0058] Comparative Example 2
[0059] The preparation process is largely the same as in Example 2, except that:
[0060] The electron transport layer uses the unmodified tin dioxide layer prepared in Comparative Example 1, without setting the TA biomimetic interface layer, and the remaining preparation steps and parameters are the same as in Example 2.
[0061] Quartz glass coated with UV-curable adhesive was adhered to the surface of the perovskite films prepared in Example 2 and Comparative Example 2. After irradiation with a UV lamp for 30 seconds, the perovskite films were lifted to expose the original buried surfaces. Scanning electron microscopy (SEM) was used to analyze the morphology of the buried surfaces, as shown in Figure 4. In Comparative Example 2 (unmodified tin dioxide interface), numerous physical pores and lead iodide residues were observed on the buried surface of the perovskite film. This indicates that the pre-deposited lead iodide film in the two-step method did not fully react with the organic amine salt, resulting in high defect states at the buried interface. In Example 2 (TA-tin dioxide / TA biomimetic interface), no physical pores were observed on the buried surface of the perovskite film. The large molecular structure and multiple coordination sites of TA loosen the bottom region of the lead iodide film, creating nanochannels that promote its full reaction with the organic amine salt. The lead iodide residue in the bottom region was significantly reduced, and the surface became denser and flatter. The results indicate that the introduction of the TA biomimetic interface layer is beneficial for the formation of high-quality perovskite crystals.
[0062] Photoluminescence (PL) and time-resolved photoluminescence (TRPL) tests were performed on the perovskite films prepared in Example 2 and Comparative Example 2, and the results are shown in Figure 5. Under laser excitation at a wavelength of 552 nm, the PL emission peak of the perovskite film prepared in Example 2 was significantly enhanced compared to Comparative Example 2, indicating less nonradiative recombination. Simultaneously, the TRPL spectrum of the perovskite film in Example 2 showed a slower decay, representing a longer carrier lifetime in the perovskite film. The results indicate that the TA-based biomimetic modified perovskite film possesses superior crystallinity and reduced defect states.
[0063] Example 3
[0064] A method for preparing a tannic acid-modified perovskite solar cell includes the following steps:
[0065] (1) The substrate pretreatment, the preparation of the TA-tin dioxide composite electron transport layer, the preparation of the TA biomimetic interface layer, and the preparation of the perovskite light-absorbing layer are all completely consistent with the steps in Example 2;
[0066] (2) Preparation of hole transport layer: Weigh 72.3 mg Spiro-OMeTAD, add it to 1 mL of chlorobenzene, then add 17.5 μL of lithium bis(trifluoromethane)sulfonamide salt solution and 29 μL of 4-tert-butylpyridine solution to the solution, stir evenly to obtain Spiro-OMeTAD hole transport layer solution; after the perovskite light-absorbing layer has completely cooled, spin-coat the solution at 5000 rpm for 30 seconds under nitrogen atmosphere, and then transfer it to a drying cabinet for oxidation for 12 hours;
[0067] (3) Metal electrode evaporation: The substrate with the hole transport layer deposited is transferred to the evaporator and deposited at 4.0 × 10⁻⁶. -4 Under a high vacuum environment of Pa, a silver electrode with a thickness of 80 nm was deposited at a rate of 1.0 Å / s. After the deposition was completed, the electrode was transferred to a drying cabinet for further oxidation for 12 hours to obtain a perovskite solar cell modified with tannic acid biomimetic technology.
[0068] Comparative Example 3
[0069] The preparation process is largely the same as in Example 3, except that:
[0070] The electron transport layer uses the unmodified tin dioxide layer prepared in Comparative Example 1, without setting the TA biomimetic interface layer, and the remaining preparation steps and parameters are the same as in Example 3.
[0071] The perovskite solar cell prepared in Example 3 was characterized by SEM cross-section, and the results are shown in Figure 6. As can be observed from the figure, the structure of each layer of the device is clear, and the contact interface between the perovskite light-absorbing layer and the TA biomimetic interface layer and electron transport layer is smooth and dense, with no obvious physical gaps.
[0072] Electrochemical impedance spectroscopy (EIS) tests were performed on the devices prepared in Example 3 and Comparative Example 3, and the fitting results are shown in Figure 7. Compared with Comparative Example 3, the device in Example 3 has a smaller series resistance and a larger recombination resistance, indicating that the introduction of the TA biomimetic interface can promote charge transport inside the battery while effectively suppressing interfacial carrier recombination. Under standard solar intensity, an area of 0.070225 cm² was used. 2 The photomask was used to perform a reverse scanning JV test on the perovskite solar cell of Example 3, and the results are shown in Figure 8. The test shows that, compared with the conventional device of Comparative Example 3, the device fabricated based on the TA biomimetic interface has a 0.069V increase in open-circuit voltage, a 2% increase in fill factor, and significantly optimized photoelectric conversion performance.
[0073] It should be noted that the above specific embodiments are only used to exemplify the technical solutions and core innovations of the present invention, and their purpose is to enable those skilled in the art to understand and implement the present invention. Any equivalent modifications, substitutions, or alterations made to the above embodiments based on the technical essence of the present invention fall within the scope of protection of the claims of the present invention.
Claims
1. A tannic acid-modified perovskite solar cell, characterized in that, The perovskite solar cell comprises, from bottom to top: a conductive substrate, a tannic acid-tin dioxide composite electron transport layer, a tannic acid biomimetic interface layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode. The tannic acid-tin dioxide composite electron transport layer is prepared by spin coating and annealing after mixing tannic acid and tin dioxide in a solution, and tannic acid and tin dioxide form a coordination effect; the tannic acid biomimetic interface layer achieves interface adhesion and defect passivation through the coordination effect of tannic acid molecules with tin dioxide and perovskite.
2. A method for preparing a perovskite solar cell modified with tannins as described in claim 1, characterized in that, Includes the following steps: S1. Clean the conductive substrate and set aside. S2. Preparation of tannic acid-tin dioxide composite electron transport layer and tannic acid biomimetic interface layer S2-1. Dissolve tannic acid powder evenly in deionized water to prepare tannic acid stock solution; S2-2. The tin dioxide stock solution is diluted with deionized water and then mixed with the tannic acid stock solution in step S2-1 to obtain a tannic acid-tin dioxide composite solution. The composite solution is spin-coated onto the surface of a conductive substrate and annealed to obtain a tannic acid-tin dioxide composite electron transport layer. S2-3. The tannic acid stock solution from step S2-1 is mixed and diluted with deionized water, and then spin-coated onto the surface of the tannic acid-tin dioxide composite electron transport layer from step S2-2. After annealing, a tannic acid biomimetic interface layer is obtained. S3. Prepare a perovskite light-absorbing layer on a tannic acid biomimetic interface layer; S4. Deposit a hole transport layer on the perovskite light-absorbing layer; S5. Deposit metal electrodes on the hole transport layer.
3. The method for preparing a tannic acid biomimetic modified perovskite solar cell according to claim 2, characterized in that, In step S2-1, the concentration of the tannic acid stock solution is 5-6 mg / mL.
4. The method for preparing a tannic acid biomimetic modified perovskite solar cell according to claim 2, characterized in that, In step S2-2, the volume ratio of tin dioxide stock solution to deionized water is 1:(4-5); and / or, the volume ratio of tannic acid stock solution to diluted tin dioxide solution is 1:(2-11).
5. The method for preparing a tannic acid biomimetic modified perovskite solar cell according to claim 2, characterized in that, In step S2-2, the spin coating environment is an air atmosphere with a humidity of 30-60%; and / or, the annealing temperature is 130-150℃ and the time is 20-30 minutes.
6. The method for preparing a tannic acid biomimetic modified perovskite solar cell according to claim 2, characterized in that, In steps S2-3, the volume ratio of tannic acid stock solution to deionized water is 1:(2-5); and / or, the spin coating environment is an air atmosphere with a humidity of 30-60%; and / or, the annealing temperature is 100-150℃ and the time is 5-10 minutes.
7. The method for preparing a tannic acid biomimetic modified perovskite solar cell according to claim 2, characterized in that, In step S1, the conductive substrate is ITO conductive glass or FTO conductive glass; the cleaning process includes sequential ultrasonic cleaning with cleaning solution, deionized water, and isopropanol, followed by drying with nitrogen.
8. The method for preparing a tannic acid biomimetic modified perovskite solar cell according to claim 2, characterized in that, In step S3, the perovskite light-absorbing layer is prepared using a two-step method in a nitrogen atmosphere.
9. The method for preparing a tannic acid biomimetic modified perovskite solar cell according to claim 2, characterized in that, In step S4, the hole transport layer material is Spiro-OMeTAD. The preparation of the Spiro-OMeTAD solution includes dissolving Spiro-OMeTAD in chlorobenzene and adding a lithium bis(trifluoromethane)sulfonamide solution and a 4-tert-butylpyridine solution.
10. The method for preparing a tannic acid biomimetic modified perovskite solar cell according to claim 2, characterized in that, In step S5, the metal electrode is silver or gold.