Double-passivation flexible perovskite solar cell and preparation method thereof

Abstract

The invention relates to the technical field of flexible perovskite solar cell preparation, in particular to a double-passivation flexible perovskite solar cell and a preparation method thereof. TBBAI (tert-butyl benzyl ammonium iodide) and PEAI (phenethyl ammonium iodide) are combined into a double passivator, comprehensive and accurate coverage of grain boundary defects and surface iodine vacancy defects of a perovskite light absorption layer is realized, synergistic interaction of the two passivators is ensured through a specific adding sequence and concentration ratio of the passivators, the non-radiative recombination rate is remarkably reduced, and the performance of the perovskite light absorption layer is improved. The charge transfer efficiency is greatly improved, the method is compatible with a low-temperature flexible PEN / ITO substrate, high-temperature damage is avoided, bending stress is effectively relieved, the mechanical stability of the device is greatly enhanced, the preparation process is simple, controllability is high, large-scale production is facilitated, and high efficiency and excellent long-term flexible stability are finally achieved.

Description

Technical Field

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

[0002] Perovskite materials, with their superior properties such as high light absorption coefficient, long carrier diffusion length, and tunable bandgap, have become a core research direction for next-generation solar cells. Flexible perovskite solar cells, with their unique advantages of being lightweight, flexible, and portable, show broad application prospects in wearable electronic devices, mobile energy supply, and other scenarios. Their core structure is usually built on a flexible transparent conductive substrate, and photoelectric conversion is achieved through the orderly stacking of functional layers.

[0003] In recent years, the photoelectric conversion efficiency of flexible perovskite solar cells has made continuous breakthroughs, but key problems such as poor stability and high defect state density still exist in practical applications. The surface flatness of flexible substrates (such as PEN / ITO) differs from that of rigid substrates, leading to the easy formation of grain boundary defects and surface dangling bonds during perovskite film growth. Simultaneously, under the mechanical forces of bending and folding, stress concentration easily occurs at the interface between the perovskite layer and the functional layer, further exacerbating defect formation. These defects become non-radiative recombination centers, reducing charge separation and transport efficiency, and accelerating the degradation of perovskite materials, severely affecting the long-term stability and output performance of the device.

[0004] To address the aforementioned issues, existing technologies often employ a single passivating agent to modify the perovskite layer surface. For example, phenylethyl ammonium salts such as phenylethyl ammonium iodide are used to passivate iodine vacancy defects on the surface, or alkyl ammonium salts are used to improve interfacial contact. However, a single passivating agent can only target a specific type of defect and cannot achieve comprehensive coverage of surface, grain boundary, and interfacial defects in the perovskite layer, resulting in limited passivation effects and difficulty in simultaneously improving device efficiency and stability. The tert-butylbenzyl group in the tert-butylbenzyl ammonium iodide molecule possesses a unique steric hindrance effect, which can functionally complement phenylethyl ammonium iodide, potentially achieving more comprehensive defect passivation and interface optimization.

[0005] Therefore, developing a synergistic dual passivation scheme of tert-butylbenzylammonium iodide and phenylethylammonium iodide to adapt to flexible PEN / ITO substrates, achieving comprehensive coverage of various types of defects in the perovskite layer, and solving the problems of incomplete defect passivation and insufficient stability in flexible perovskite solar cells has important practical application value. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a double-passivated flexible perovskite solar cell and its preparation method. By using the synergistic passivation effect of tert-butylbenzylammonium iodide and phenylethylammonium iodide, comprehensive coverage of various types of defects in the perovskite layer can be achieved, so as to solve the problems of complex defect types, limited passivation effect of single passivating agent, and difficulty in balancing device efficiency and stability in the existing flexible perovskite solar cells.

[0007] To achieve the above objectives, the present invention provides a double-passivated flexible perovskite solar cell, which comprises, from bottom to top, a substrate, an electron transport layer, a perovskite light-absorbing layer, a double passivation layer, a hole transport layer, and a top electrode. The double passivation layer is formed by spin-coating a double passivation agent onto the perovskite light-absorbing layer.

[0008] The dual passivating agent is formed by adding phenylethyl ammonium iodide solution dropwise to tert-butylbenzyl ammonium iodide solution.

[0009] Preferably, the concentration of the tert-butylbenzylammonium iodide solution is 5 mg / mL.

[0010] Preferably, the concentration of the phenylethyl ammonium iodide solution is 1-8 mg / mL, more preferably 3-7 mg / mL.

[0011] Preferably, the volume ratio of the phenylethyl ammonium iodide solution to the tert-butylbenzyl ammonium iodide solution is 1:1.

[0012] Preferably, the substrate is a PEN / ITO flexible substrate, which is subjected to ultrasonic cleaning in acetone, anhydrous ethanol, and deionized water, nitrogen blowing, vacuum drying, and ultraviolet ozone pretreatment in sequence before use.

[0013] Preferably, the thickness of the PEN / ITO substrate is 125 μm and the transmittance is 75%-85%.

[0014] Preferably, the wavelength of the ultraviolet lamp irradiation for the ultraviolet ozone pretreatment is 185nm, and the treatment time is 3-10min.

[0015] Preferably, the electron transport layer is formed by spin-coating a SnO2 dispersion onto a flexible PEN / ITO substrate and then annealing it.

[0016] Preferably, the SnO2 aqueous solution has a concentration of 15%.

[0017] Preferably, the SnO2 dispersion is diluted with deionized water to a concentration of 1%-10% before spin coating.

[0018] Preferably, the spin coating followed by annealing is at a temperature of 100-150°C and the annealing time is 30 minutes.

[0019] Preferably, the spin-coating amount of the SnO2 dispersion is per 3 cm.2 Add 10-80 μL dropwise.

[0020] Preferably, the perovskite light-absorbing layer is MA. 0.85 FA 0.15 The PbI3 precursor solution is spin-coated onto the surface of the electron transport layer to form the layer.

[0021] Preferably, the MA 0.85 FA 0.15 The molar concentration of the PbI3 precursor solution was 1.00-1.70 mol / L.

[0022] Preferably, the MA 0.85 FA 0.15 The solvent for the PbI3 precursor solution is a mixture of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 4:1).

[0023] Preferably, the thickness of the double passivation layer is 1-5 nm.

[0024] Preferably, the hole transport layer is formed by coating the Spiro-OMeTAD hole transport layer precursor liquid onto the double passivation layer.

[0025] Preferably, the ratio of Spiro-OMeTAD, lithium bis(trifluoromethanesulfonylimide) acetonitrile solution, and 4-tert-butylpyridine in the Spiro-OMeTAD hole transport layer precursor solution is 72.3 mg: 17.5 μL: 28.8 μL.

[0026] Preferably, the concentration of the acetonitrile solution of lithium bis(trifluoromethanesulfonylimide) is 520 mg / mL.

[0027] Preferably, the top electrode is formed by depositing a metal electrode on the surface of the hole transport layer using a thermal evaporation method.

[0028] Preferably, the metal electrode is either a gold electrode or a silver electrode.

[0029] Preferably, the thickness of the top electrode is 50-300 nm.

[0030] Preferably, the thermal evaporation rate is 0.001-0.5 nm / s.

[0031] Furthermore, the present invention also provides a method for preparing a tert-butylbenzylammonium iodide / phenylethylammonium iodide double-passivated flexible perovskite solar cell, comprising the following steps: sequentially preparing an electron transport layer, a perovskite light-absorbing layer, a double passivation layer, a hole transport layer, and a top electrode on a substrate to obtain a double-passivated flexible perovskite solar cell.

[0032] The beneficial effects of this invention are:

[0033] This invention employs a unique dual passivation layer design to maximize the passivation effect. By precisely controlling the relative content of two organic passivators with different molecular sizes and passivation properties, it ensures accurate coverage and effective repair of grain boundary defects inside the perovskite layer and iodine vacancy defects on the surface, greatly reducing nonradiative recombination of charge carriers. Simultaneously, the order of passivator addition has been innovatively optimized, employing a specific addition method to effectively avoid potential aggregation between the two passivator molecules, ensuring their uniform dispersion in solution and synergistic effect in the thin film. This synergistic and precise defect passivation strategy significantly improves the carrier lifetime and transport efficiency of the perovskite thin film, laying a solid foundation for high-performance devices.

[0034] This invention fully considers the special requirements of flexible devices in material selection and process design, demonstrating excellent flexibility and adaptability. The entire battery structure is designed based on a flexible PEN / ITO substrate, and each functional layer uses materials compatible with low-temperature processing, effectively avoiding performance damage or structural destruction that traditional high-temperature processing may cause to the flexible substrate. Furthermore, the double passivation layer effectively alleviates the interfacial stress generated between the perovskite layer and the hole transport layer during repeated bending of the flexible device, significantly enhancing the mechanical stability of the device. This ingenious structural design allows the flexible perovskite solar cell to maintain a very high proportion of its initial performance after numerous bending cycles, fully demonstrating excellent flexibility and long-term service durability.

[0035] The preparation process proposed in this invention has strong controllability and good industrialization prospects. In the preparation of the dual passivating agents, the concentration of one passivating agent is fixed; the passivation effect can be precisely controlled simply by adjusting the concentration of the other passivating agent and its mixing order with the fixed-concentration passivating agent. This simplified process parameter setting greatly reduces the complexity of operation, making the entire preparation process easy to control and highly repeatable.

[0036] The fabrication method of this invention does not require expensive and complex equipment, and has the advantages of simple operation and high cost-effectiveness, making it very suitable for large-scale industrial production. This highly controllable and adaptable fabrication process, combined with the synergistic passivation effect and flexible adaptation characteristics mentioned above, enables the flexible perovskite solar cells fabricated by this invention to achieve excellent photoelectric conversion efficiency and outstanding comprehensive performance, laying a solid foundation for their promotion in practical applications. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0038] Figure 1 This is a schematic diagram of the structure of the flexible perovskite solar cell with tert-butylbenzylammonium iodide / phenylethylammonium iodide double passivation in Example 2 of the present invention;

[0039] Figure 2 The images are scanning electron microscope (SEM) images of the perovskite layer of the tert-butylbenzylammonium iodide / phenylethylammonium iodide double-passivated flexible perovskite solar cell of the present invention, wherein a, b, c, and d are the scanning electron microscope (SEM) images of the perovskite layer of the double-passivated flexible perovskite solar cell obtained in Examples 1, 2, 3 and Comparative Example 2, respectively.

[0040] Figure 3 The normalized PCE diagrams are for the flexible perovskite solar cells obtained in Example 2 and Comparative Example 4 of this invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0042] Example 1: A double-passivated flexible perovskite solar cell, the structure of which is shown in the attached figure. Figure 1 From bottom to top, the layers are: PEN / ITO substrate, SnO2 electron transport layer, MA 0.85 FA 0.15 The specific fabrication steps for the PbI3 perovskite light-absorbing layer, the tert-butylbenzylammonium iodide / phenylethylammonium iodide double passivation layer, the Spiro-OMeTAD hole transport layer, and the silver top electrode are as follows:

[0043] (1) Pretreatment of PEN / ITO substrate: The PEN / ITO substrate was placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 15 min each, dried with nitrogen and then dried in a vacuum drying oven at 80℃ for 20 min to obtain a clean and dry flexible substrate. It was then placed in an ultraviolet ozone cleaner for ultraviolet ozone pretreatment. The wavelength of the ultraviolet lamp was 185nm and the treatment time was 3 min.

[0044] (2) Preparation of SnO2 electron transport layer: The SnO2 dispersion (concentration 15%) was diluted with deionized water to a concentration of 1%, and then applied to a PEN / ITO substrate (3cm²). 2 10 μL of SnO2 aqueous solution was added to the PEN / ITO substrate and the solution was spread completely with a pipette. The solution was then spin-coated onto the PEN / ITO substrate at 2000 rpm for 20 s. The substrate was then annealed on a hot plate at 100 °C for 30 min to form a SnO2 electron transport layer.

[0045] (3) Preparation of perovskite light-absorbing layer: Using a mixture of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 4:1) as solvent, prepare 1.00 mol / L MA 0.85 FA0.15 PbI3 precursor solution, 60 μL of precursor solution was spin-coated onto the surface of SnO2 electron transport layer at 1000 rpm for 5 s, and then spin-coated at 3000 rpm for 30 s. 22 s before the end of spin-coating, 120 μL of ethyl acetate was added as an antisolvent. Then it was annealed on a hot stage at 100℃ for 15 min to form a perovskite light-absorbing layer.

[0046] (4) Preparation of double passivation layer: Using isopropanol as solvent, first prepare a 5 mg / mL tert-butylbenzyl ammonium iodide solution, then prepare a 3 mg / mL phenylethyl ammonium iodide solution. Slowly add the phenylethyl ammonium iodide solution to the tert-butylbenzyl ammonium iodide solution (volume ratio of the two is 1:1) while stirring at 500 rpm for 15 min to obtain a uniformly mixed double passivating agent. Then spin-coat the double passivating agent on the surface of the perovskite light-absorbing layer at 4000 rpm for 20 s without annealing to form a double passivation layer with a thickness of 1 nm.

[0047] (5) Preparation of Spiro-OMeTAD hole transport layer: 72.3 mg Spiro-OMeTAD, 17.5 μL of acetonitrile solution of lithium bis(trifluoromethanesulfonylimide) with a concentration of 520 mg / mL, and 28.8 μL of 4-tert-butylpyridine were dissolved in 1 mL of chlorobenzene to obtain the Spiro-OMeTAD hole transport layer precursor solution. Then, 60 μL of this precursor solution was dropped onto the light-absorbing layer of the perovskite thin film. The spin coating speed was 3000 rpm and the acceleration was 1500 rpm / s. 2 The time was 30s, a 100nm hole transport layer was prepared, and it was prepared for scraping and evaporation (i.e., the film at the common electrode was scraped off with a cotton swab dipped in DMF, the device was then put into a 6×8 evaporation template, the evaporation template was placed into the evaporation chamber, and evaporation was performed after vacuuming).

[0048] (6) Preparation of silver top electrode: A silver electrode is deposited on the surface of the hole transport layer by thermal evaporation. When the vacuum degree of the evaporation chamber reaches 5×10 -4 After Pa, the heating power supply was turned on, and silver was deposited at a rate of 0.001 nm / s to a thickness of 50 nm. The effective area of ​​the cell deposited by the evaporation template was 0.12 cm². 2 This forms a double-passivated flexible perovskite solar cell.

[0049] Example 2: A double-passivated flexible perovskite solar cell, the structure of which is shown in the attached figure. Figure 1 From bottom to top, the layers are: PEN / ITO substrate, SnO2 electron transport layer, MA 0.85 FA 0.15The specific fabrication steps for the PbI3 perovskite light-absorbing layer, the tert-butylbenzylammonium iodide / phenylethylammonium iodide double passivation layer, the Spiro-OMeTAD hole transport layer, and the silver top electrode are as follows:

[0050] (1) Pretreatment of PEN / ITO substrate: The PEN / ITO substrate was placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 20 min each, dried with nitrogen and then dried in a vacuum drying oven at 80℃ for 40 min to obtain a clean and dry flexible substrate. It was then placed in an ultraviolet ozone cleaner for ultraviolet ozone pretreatment. The wavelength of the ultraviolet lamp was 185 nm and the treatment time was 7 min.

[0051] (2) Preparation of SnO2 electron transport layer: The SnO2 dispersion (concentration 15%) was diluted with deionized water to a concentration of 5%, and then applied to a PEN / ITO substrate (3cm²). 2 Add 40 μL of SnO2 aqueous solution to the substrate and spread the solution completely with a pipette. Spin-coat the solution onto the PEN / ITO substrate at 3000 rpm for 40 s. Then anneal on a hot plate at 130 °C for 30 min to form a SnO2 electron transport layer.

[0052] (3) Preparation of perovskite light-absorbing layer: Using a mixture of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 4:1) as solvent, prepare 1.35 mol / L MA 0.85 FA 0.15 PbI3 precursor solution, 60 μL of precursor solution was spin-coated onto the surface of SnO2 electron transport layer at 1000 rpm for 10 s, and then spin-coated at 3000-5000 rpm for 35 s. 22 s before the end of spin-coating, 120 μL of ethyl acetate was added as an antisolvent. Then it was annealed on a hot stage at 130℃ for 20 min to form a perovskite light-absorbing layer.

[0053] (4) Preparation of double passivation layer: Using isopropanol as solvent, first prepare a tert-butylbenzyl ammonium iodide solution with a concentration of 5 mg / mL, then prepare a phenylethyl ammonium iodide solution with a concentration of 5 mg / mL. Slowly add the phenylethyl ammonium iodide solution to the tert-butylbenzyl ammonium iodide solution (volume ratio of the two is 1:1) while adding dropwise and stirring at 800 rpm for 30 min to obtain a uniformly mixed double passivating agent. Then spin-coat the double passivating agent on the surface of the perovskite light-absorbing layer at a speed of 5000 rpm for 30 s. No annealing is required to form a double passivation layer with a thickness of 3 nm.

[0054] (5) Preparation of Spiro-OMeTAD hole transport layer: 72.3 mg Spiro-OMeTAD, 17.5 μL of acetonitrile solution of lithium bis(trifluoromethanesulfonylimide) with a concentration of 520 mg / mL, and 28.8 μL of 4-tert-butylpyridine were dissolved in 1 mL of chlorobenzene to obtain the Spiro-OMeTAD hole transport layer precursor solution. Then, 60 μL of this precursor solution was dropped onto the light-absorbing layer of the perovskite thin film. The spin coating speed was 3000 rpm and the acceleration was 1500 rpm / s. 2 The time was 30s, a 100nm hole transport layer was prepared, and it was prepared for scraping and evaporation (i.e., the film at the common electrode was scraped off with a cotton swab dipped in DMF, the device was then put into a 6×8 evaporation template, the evaporation template was placed into the evaporation chamber, and evaporation was performed after vacuuming).

[0055] (6) Preparation of silver top electrode: A silver electrode is deposited on the surface of the hole transport layer by thermal evaporation. When the vacuum degree of the evaporation chamber reaches 5×10 -4 After Pa, the heating power supply was turned on, and silver was deposited at a rate of 0.3 nm / s to a thickness of 150 nm. The effective area of ​​the cell deposited by the evaporation template was 0.12 cm². 2 This forms a double-passivated flexible perovskite solar cell.

[0056] Example 3: A double-passivated flexible perovskite solar cell, the structure of which is shown in the attached figure. Figure 1 From bottom to top, the layers are: PEN / ITO substrate, SnO2 electron transport layer, MA 0.85 FA 0.15 The specific fabrication steps for the PbI3 perovskite light-absorbing layer, the tert-butylbenzylammonium iodide / phenylethylammonium iodide double passivation layer, the Spiro-OMeTAD hole transport layer, and the silver top electrode are as follows:

[0057] (1) Pretreatment of PEN / ITO substrate: The PEN / ITO substrate was placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 30 min each, dried with nitrogen and then dried in a vacuum drying oven at 80℃ for 60 min to obtain a clean and dry flexible substrate. It was then placed in an ultraviolet ozone cleaner for ultraviolet ozone pretreatment. The wavelength of the ultraviolet lamp was 185 nm and the treatment time was 10 min. It was ready for use.

[0058] (2) Preparation of SnO2 electron transport layer: The SnO2 dispersion (concentration 15%) was diluted with deionized water to a concentration of 10%, and then applied to a PEN / ITO substrate (3cm²). 2 Add 80 μL of SnO2 aqueous solution to the substrate and spread the solution completely with a pipette. Spin-coat the solution onto the PEN / ITO substrate at 4000 rpm for 60 s. Then anneal on a hot plate at 150 °C for 30 min to form a SnO2 electron transport layer.

[0059] (3) Preparation of perovskite light-absorbing layer: Using a mixture of N,N-dimethylformamide and dimethyl sulfoxide (volume ratio 4:1) as solvent, prepare 1.70 mol / L MA 0.85 FA 0.15 PbI3 precursor solution, 60 μL of precursor solution was spin-coated onto the surface of SnO2 electron transport layer at 1000 rpm for 15 s, and then spin-coated at 5000 rpm for 40 s. 22 s before the end of spin-coating, 120 μL of ethyl acetate was added as an antisolvent. Then it was annealed on a hot stage at 150℃ for 30 min to form a perovskite light-absorbing layer.

[0060] (4) Preparation of double passivation layer: Using isopropanol as solvent, first prepare a tert-butylbenzyl ammonium iodide solution with a concentration of 5 mg / mL, and then prepare a phenylethyl ammonium iodide solution with a concentration of 7 mg / mL. Slowly add the phenylethyl ammonium iodide solution to the tert-butylbenzyl ammonium iodide solution (volume ratio of the two is 1:1) while adding dropwise and stirring at 1000 rpm for 45 min to obtain a uniformly mixed double passivating agent. Then spin-coat the double passivating agent on the surface of the perovskite light-absorbing layer at a speed of 6000 rpm for 40 s. No annealing is required to form a double passivation layer with a thickness of 5 nm.

[0061] (5) Preparation of Spiro-OMeTAD hole transport layer: 72.3 mg Spiro-OMeTAD, 17.5 μL of acetonitrile solution of lithium bis(trifluoromethanesulfonylimide) with a concentration of 520 mg / mL, and 28.8 μL of 4-tert-butylpyridine were dissolved in 1 mL of chlorobenzene to obtain the Spiro-OMeTAD hole transport layer precursor solution. Then, 60 μL of this precursor solution was dropped onto the light-absorbing layer of the perovskite thin film. The spin coating speed was 3000 rpm and the acceleration was 1500 rpm / s. 2 The time was 30s, a 100nm hole transport layer was prepared, and it was prepared for scraping and evaporation (i.e., the film at the common electrode was scraped off with a cotton swab dipped in DMF, the device was then put into a 6×8 evaporation template, the evaporation template was placed into the evaporation chamber, and evaporation was performed after vacuuming).

[0062] (6) Preparation of silver top electrode: A silver electrode is deposited on the surface of the hole transport layer by thermal evaporation. When the vacuum degree of the evaporation chamber reaches 5×10 -4 After Pa, the heating power was turned on, and silver was deposited at a rate of 0.5 nm / s to a thickness of 300 nm. The effective area of ​​the cell deposited by the evaporation template was 0.12 cm². 2 This forms a double-passivated flexible perovskite solar cell.

[0063] Comparative Example 1: The difference from Example 2 is that the passivating agent in step (4) does not contain tert-butylbenzyl ammonium iodide solution, while the other conditions are the same as in Example 2.

[0064] Comparative Example 2: The difference from Example 2 is that the passivating agent in step (4) does not contain phenylethyl ammonium iodide solution, while the other conditions are the same as in Example 2.

[0065] Comparative Example 3: The difference from Example 2 is that in step (4), the tert-butylbenzyl ammonium iodide solution is slowly added dropwise to the phenylethyl ammonium iodide solution, while the other conditions are the same as in Example 2.

[0066] Comparative Example 4: The difference from Example 2 is that no passivation layer is prepared, while the other conditions are the same as in Example 2.

[0067] Performance testing

[0068] Scanning electron microscopy (SEM) tests were performed on the perovskite films obtained in Examples 1, 2, 3, and Comparative Example 3. The test results are shown in the figure. Figure 2 .

[0069] Repeated bending test: The flexible device was subjected to 4000 repeated bends with a radius of 5mm using a mechanical bending instrument. Efficiency tests were then conducted on the devices after the initial bending and after bending for 500, 1000, 1500, 2000, 3000, and 4000 cycles. The test results are shown in […]. Figure 3 .

[0070] Photoelectric performance testing: Under simulated AM1.5G standard sunlight irradiation conditions (light intensity of 100mW / cm²), 2 The current-voltage curves (JV) and photoelectric conversion efficiency data of the perovskite solar cells prepared in Examples 1-3 and Comparative Examples 1-4 were tested respectively. The scanning voltage during the test was 1.3V→-0.1V, and the scanning interval was 20mV. The results are shown in Table 1.

[0071] Table 1 Performance Test Results

[0072] passivating agent preparation method <![CDATA[Jsc(mA / cm 2 )]]> Voc(mV) FF (%) PCE (%) Example 1 First, tert-butylbenzyl ammonium iodide followed by phenylethyl ammonium iodide (volume ratio 5:3) 22.35 1.17 78.65 20.57 Example 2 First, tert-butylbenzyl ammonium iodide followed by phenylethyl ammonium iodide (volume ratio 5:5) 22.52 1.18 80.83 21.48 Example 3 First, tert-butylbenzyl ammonium iodide followed by phenylethyl ammonium iodide (volume ratio 5:7) 22.40 1.17 80.08 20.91 Comparative Example 1 Mono-tert-butylbenzylammonium iodide 21.94 1.14 77.56 19.43 Comparative Example 2 Monophenylethylammonium iodide 22.11 1.15 75.97 19.31 Comparative Example 3 First, phenethyl ammonium iodide, then tert-butylbenzyl ammonium iodide (volume ratio 5:5). 22.19 1.16 78.63 20.31 Comparative Example 4 No passivating agent added 21.77 1.12 75.75 18.61

[0073] Data Analysis: Figure 2 The images shown are SEM images of the perovskite layers obtained in Examples 1, 2, 3, and Comparative Example 3 of this invention. Figure 2It can be seen that when phenylethyl ammonium iodide solution is added to tert-butylbenzyl ammonium iodide solution, the relatively smaller phenylethyl ammonium iodide preferentially fills the grain boundaries and micro-interstits, providing an ordered substrate for the subsequent coating of the relatively larger tert-butylbenzyl ammonium iodide. Furthermore, as the proportion of phenylethyl ammonium iodide increases, the grains grow uniformly, resulting in a denser and smoother film with fewer defects. However, when the feeding order is reversed, the relatively larger tert-butylbenzyl ammonium iodide preemptively occupies the surface and grain boundary sites, hindering the penetration and coordination of phenylethyl ammonium iodide. Even under the same ratio, this leads to finer grains, a rougher surface, significant phase segregation, and a substantial decrease in film quality.

[0074] Figure 3 For the repeated bending experiment shown, by Figure 3 It can be seen that the device with double passivation treatment exhibits a slower efficiency decline under repeated bending, and can still maintain more than 80% of its initial efficiency after 4000 bending cycles. In contrast, the device without passivation exhibits a faster efficiency decline, and can only maintain less than 40% of its initial efficiency after 4000 bending cycles.

[0075] As shown in Table 1, the tert-butylbenzylammonium iodide / phenylethylammonium iodide dual-passivated flexible perovskite solar cells prepared in Examples 1, 2, and 3 of this invention exhibit significantly higher photoelectric conversion efficiency than comparative examples 1-2, which use single passivating agents, due to the synergistic passivation effect of tert-butylbenzylammonium iodide and phenylethylammonium iodide. Furthermore, with a specific feeding sequence (adding phenylethylammonium iodide solution to tert-butylbenzylammonium iodide solution), the relatively smaller phenylethylammonium iodide fills the microscopic gaps first, forming a rigid coating layer on the surface. This results in a dense interface with fewer defects, adapting to grain boundaries and surface dual passivation, thereby optimizing interfacial bonding. This allows the device to maintain a high efficiency retention rate and excellent flexibility stability even after cyclic bending. Conversely, when the feeding sequence is reversed, the relatively larger tert-butylbenzylammonium iodide occupies the surface / grain boundary sites first, hindering the penetration and coordination of phenylethylammonium iodide, easily leaving voids and causing phase segregation, leading to poor passivation and carrier transport.

[0076] In summary, this invention utilizes the synergistic passivation effect of tert-butylbenzylammonium iodide and phenylethylammonium iodide to simultaneously cover surface iodine vacancies, grain boundary defects, and interfacial stress concentration areas in the perovskite layer. The comprehensiveness of defect passivation is significantly better than that of a single passivating agent scheme, effectively reducing non-radiative recombination rate and greatly improving charge transport efficiency. Furthermore, this invention is adaptable to the characteristics of flexible PEN / ITO substrates, and each functional layer adopts low-temperature flexible compatible materials and processes to avoid high-temperature damage to the flexible substrate. The dual passivation layer can alleviate interfacial stress during device bending, significantly improving the efficiency retention rate of the flexible battery after cyclic bending and resulting in better long-term service stability.

[0077] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A double-passivated flexible perovskite solar cell, comprising, from bottom to top, a substrate, an electron transport layer, a perovskite light-absorbing layer, a double passivation layer, a hole transport layer, and a top electrode, characterized in that, The double passivation layer is formed by spin-coating a double passivating agent onto a perovskite light-absorbing layer; the double passivating agent is formed by adding a phenylethyl ammonium iodide solution dropwise into a tert-butylbenzyl ammonium iodide solution.

2. The double-passivated flexible perovskite solar cell according to claim 1, characterized in that, The concentration of the tert-butylbenzyl ammonium iodide solution is 5 mg / mL, the concentration of the phenylethyl ammonium iodide solution is 1-8 mg / mL, and the volume ratio of the phenylethyl ammonium iodide solution to the tert-butylbenzyl ammonium iodide solution is 1:

1.

3. The double-passivated flexible perovskite solar cell according to claim 1, characterized in that, The substrate is a PEN / ITO flexible substrate, which is subjected to ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water, nitrogen blowing, vacuum drying, and ultraviolet ozone pretreatment in sequence before use.

4. The double-passivated flexible perovskite solar cell according to claim 1, characterized in that, The electron transport layer is formed by spin-coating a SnO2 dispersion onto a flexible PEN / ITO substrate and then annealing it.

5. The double-passivated flexible perovskite solar cell according to claim 1, characterized in that, The perovskite light-absorbing layer is MA 0.85 FA 0.15 The PbI3 precursor solution is spin-coated onto the surface of the electron transport layer to form the layer.

6. The double-passivated flexible perovskite solar cell according to claim 1, characterized in that, The thickness of the double passivation layer is 1-5 nm.

7. The double-passivated flexible perovskite solar cell according to claim 1, characterized in that, The hole transport layer is formed by spinning Spiro-OMeTAD hole transport layer precursor liquid onto the double passivation layer, and the thickness of the top electrode is 50-300 nm.

8. The double-passivated flexible perovskite solar cell according to claim 1, characterized in that, The top electrode is formed by depositing a metal electrode on the surface of the hole transport layer using a thermal evaporation method, and the thickness of the top electrode is 50-300 nm.

9. A method for fabricating a double-passivated flexible perovskite solar cell according to any one of claims 1-8, characterized in that, Includes the following steps: By sequentially fabricating an electron transport layer, a perovskite light-absorbing layer, a double passivation layer, a hole transport layer, and a top electrode on a substrate, a double passivation flexible perovskite solar cell can be obtained.

Images