Efficient and stable perovskite solar cell based on one-dimensional fluorine-containing formamidine single crystal modification and preparation method of efficient and stable perovskite solar cell

Abstract

The invention relates to the field of perovskite solar cells, and discloses a preparation method of an efficient and stable perovskite solar cell based on one-dimensional fluorine-containing formamidine single crystal modification, and the method comprises the steps: selecting transparent conductive glass as a substrate; a [2-(3, 6-dimethoxy-9H-carbazole-9-yl) ethyl] phosphonic acid solution is taken to be subjected to spin coating on the surface of the substrate, and a hole transport layer is obtained; spin-coating a perovskite precursor solution containing one-dimensional fluorine-containing formamidine perovskite single crystals on the hole transport layer to obtain a perovskite thin film; dropwise adding an electron transport layer precursor solution on the surface of the perovskite thin film for spin coating to obtain an electron transport layer; and preparing a metal electrode. According to the invention, the one-dimensional fluoroformamidine-containing perovskite single crystal and the three-dimensional perovskite double-anchoring lattice matching are utilized, the quality and the photoelectric property of the solar cell film are synergistically optimized, the efficiency of the perovskite solar cell device is 25.54%, and the unpackaged device still keeps 90.13% of the initial efficiency after 1000 hours under the environmental condition, so that the stability is excellent.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cells, and more particularly to a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification and its preparation method. Background Technology

[0002] Solar energy, as one of the most abundant renewable energy sources, plays a crucial role in alleviating environmental problems and meeting energy demands through its efficient utilization. Perovskite materials have attracted widespread attention in the field of solar cells due to their excellent photoelectric properties (such as high light absorption, good carrier mobility, and easily tunable bandgap). These characteristics give perovskite solar cells the potential to compete with traditional silicon-based solar cells in terms of photoelectric conversion efficiency. Although perovskite solar cells have developed rapidly in a short period, their easy decomposition of the light-absorbing layer, poor device stability, and difficulty in large-area fabrication severely hinder their further development and large-scale commercialization.

[0003] In solar photovoltaic material systems, constructing low-dimensional / three-dimensional (e.g., 2D / 3D) heterojunctions is a key strategy for improving device efficiency. For example, Chinese patent CN202210347749.8 discloses a formamidinium-based two-dimensional perovskite thin film, its preparation method, and its application. It selects linear organic diamine spacer cations to form the layered crystal structure of the two-dimensional perovskite. Although the two-dimensional perovskite passivation layer can improve environmental stability through hydrophobic organic cations, it is prone to phase transformation into a quasi-two-dimensional structure (n ≥ 2) during long-term operation, thus weakening the passivation effect. The success of two-dimensional / three-dimensional structure matching largely depends on the crystal orientation of the two-dimensional layers. Efficient interlayer charge transport can only be achieved when the inorganic layers (quantum wells) of the two-dimensional perovskite are almost perpendicular to the substrate. However, the fabrication of perovskite solar cells is mostly based on solution methods or vapor deposition processes. In solution-processed films, the two-dimensional crystal phase tends to exhibit random orientation, even parallel alignment with the substrate. This creates a significant energy barrier, severely limiting the fill factor and current density, resulting in the inability to obtain efficient and stable solar cells. Therefore, it is essential to develop efficient and stable perovskite solar cells and their fabrication methods. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing perovskite solar cells, which solves the problems of low conversion efficiency and poor stability of existing solar cells.

[0005] The present invention relates to a method for preparing a high-efficiency and stable perovskite solar cell modified with one-dimensional fluorinated formamidinium single crystal, comprising the following steps: (1) selecting a transparent conductive glass as a substrate; (2) spin-coating a [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid solution onto the substrate surface to obtain a hole transport layer; (3) spin-coating a perovskite precursor solution containing one-dimensional fluorinated formamidinium perovskite single crystal onto the hole transport layer to obtain a perovskite thin film; (4) dropping an electron transport layer precursor solution onto the surface of the perovskite thin film and spin-coating to obtain an electron transport layer; subsequently, spin-coating a 2,9-dimethyl-4,7-biphenyl-1,10-o-diazaphenanthroline solution onto the surface of the electron transport layer; and (5) preparing a metal electrode.

[0006] Preferably, the perovskite precursor solution contains 5-9 mg / mL of one-dimensional fluorinated formamidinium perovskite single crystals.

[0007] Preferably, the amount of perovskite precursor solution containing fluorinated formamidinium perovskite single crystal is 60-100 μL, and the perovskite precursor solution contains 5 mg / mL of one-dimensional fluorinated formamidinium perovskite single crystal.

[0008] Preferably, the one-dimensional fluorinated formamidine single crystal is prepared by the following method: p-fluorobenzamide hydrochloride and PbI2 are dissolved in an acidic solution, heated and stirred until completely dissolved, then cooled to room temperature to precipitate single crystals, and then washed, filtered and dried to obtain the crystals.

[0009] Preferably, the mass ratio of benzamide hydrochloride to PbI2 is 1:1.

[0010] Preferably, the volume ratio of HI to HPO3 in the acidic solution is 5:1.

[0011] Preferably, in step (2), the amount of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) solution used is 60-100 μL, and the concentration is 0.1-1 mg / mL.

[0012] Preferably, in step (4), the amount of electron transport layer precursor solution used is 80-100 μL, and the concentration is 15-25 mg / mL.

[0013] Preferably, in step (4), the electron transport layer precursor solution is prepared by dissolving isomethyl [6,6]-phenyl-C71-butyrate in chlorobenzene.

[0014] In another aspect, the present invention provides a high-efficiency and stable perovskite solar cell modified with one-dimensional fluorinated formamidinium single crystals prepared by the above method.

[0015] This invention provides a method for fabricating perovskite solar cells based on one-dimensional fluorinated formamidinium-based perovskite single crystals. By matching the planes (002) and (021) of the one-dimensional fluorinated formamidinium-based perovskite single crystal with the dual-anchored lattice of the three-dimensional perovskite, low-strain nucleation sites are provided for the three-dimensional perovskite lattice, reducing defects and effectively improving the crystallinity of the three-dimensional perovskite, increasing grain size, and efficiently passivating lead / iodine vacancy defects. This significantly suppresses non-radiative recombination and extends carrier lifetime. Based on these unique structures, the quality of the solar cell film and photoelectric performance are synergistically optimized, enabling the perovskite solar cell device to achieve an efficiency of 25.54%. Furthermore, the unencapsulated device retains 90.13% of its initial efficiency after 1000 hours under environmental conditions, demonstrating excellent stability. Attached Figure Description

[0016] Figure 1 Simulated and experimental X-ray diffraction (XRD) patterns of (TFBZ)PbI3 and (BZ)2Pb1.5I4 single crystals;

[0017] Figure 2 a and 2b represent high-resolution transmission electron microscopy (HRTEM) images of one-dimensional / 3D hybrid perovskite heteroepitaxial regions doped with 20 mg / mL one-dimensional (BZ)2Pb1.5I4 and one-dimensional (TFBZ)PbI3 single crystals, respectively.

[0018] Figure 3 a shows top scanning electron microscope (SEM) images of the control group, BZ / PVK, and TFBZ / PVK perovskite films; 3b shows cross-sectional scanning electron microscope (SEM) images of the control group, BZ / PVK, and TFBZ / PVK perovskite solar cells.

[0019] Figure 4 The XRD patterns are of perovskite precursor solutions containing perovskite single crystals of different concentrations, where a represents (BZ)2Pb1.5I4 single crystal and b represents (TFBZ)PbI3 single crystal.

[0020] Figure 5 JV plots for the control group, BZ / PVK, and TFBZ / PVK devices;

[0021] Figure 6 The graph shows the stability test results of the control group, BZ / PVK and TFBZ / PVK devices under specific environmental conditions (40 ± 5% relative humidity, room temperature) for 1000 h. Detailed Implementation

[0022] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0023] Example 1: A method for preparing fluorobenzamide-based perovskite single crystals, comprising the following steps: Weighing 0.225 g of p-fluorobenzamide hydrochloride and 0.231 g of PbI2 and dissolving them in 6 mL of acidic solution (HI:HPO3 volume ratio of 3:1), stirring until completely dissolved under heating to 180°C, then stopping heating, cooling to room temperature to precipitate single crystals, then washing and filtering with diethyl ether, and finally placing in a vacuum drying oven at 80°C for 24 h to obtain p-fluorobenzamide perovskite single crystals (TFBZ)PbI3.

[0024] Example 2: A method for fabricating a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification, comprising the following steps:

[0025] (1) Preparation of transparent ITO conductive glass: First, clean the indium tin oxide glass (ITO) in an ultrasonic bath for 20 min with detergent, deionized water, ethanol, acetone and isopropanol in sequence, then put it in a drying oven to dry, and finally ozonate it with ultraviolet light for 15 min before use.

[0026] (2) Preparation of hole transport layer: The pretreated ITO glass was transferred to a glove box, and the spin coater was set to 3000 rpm / s. 60 μL of 1 mg / mL [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) solution was spin-coated on the ITO surface for 30 s. Then the glass was transferred to a ceramic heating table and annealed at 100℃ for 15 min.

[0027] (3) Hole transport layer modified based on one-dimensional fluorobenzamide-based perovskite single crystal: 5 mg of p-fluorobenzamide perovskite single crystal was dissolved in 1 mL of 3D perovskite precursor solution (FA). 0.95 MA 0.05 Pb(I 0.95 Br 0.05)3 The perovskite precursor solution modified with fluorinated formamidinium perovskite single crystals was obtained by stirring at room temperature for 5 h. 70 μL of the perovskite precursor solution with a concentration of 5 mg / mL fluorinated formamidinium perovskite single crystals was dropped onto the surface of the hole transport layer after step (2). A two-step spin coating process was used: first, a spin coating process at 1000 rpm for 10 s; then, a spin coating process at 5000 rpm for 35 s, with an acceleration set to 2000 rpm / s. Simultaneously, 120 μL of the anti-solvent chlorobenzene was added dropwise at the 15th second. After spin coating, the perovskite precursor solution was annealed at 110℃ for 1 h on a ceramic heating stage and then cooled to room temperature. 0.95MA 0.05 Pb(I 0.95 Br 0.05)3 It was obtained by dissolving 706.9 mg PbI2, 27.05 mg PbBr2, 240.76 mg FAI, 8.21 mg MABr and 33.76 mg MACl in a mixed solvent of 1 mL DMF and DMSO (4:1, v / v).

[0028] (4) Preparation of the electron transport layer: 80 μL of a 15 mg / mL electron transport layer precursor solution was dropped onto the surface of the perovskite film treated in step (3). The spin coater speed was set to 1500 rpm / 30s and the acceleration was set to 2000 rpm / s. Then, the film was annealed at 100 ℃ for 10 min on a ceramic heating stage. 60 μL of a 0.5 mg / mL solution of 2,9-dimethyl-4,7-biphenyl-1,10-o-diazaphenanthroline isopropanol was spin-coated at 5000 rpm for 30 s. The electron transport layer was prepared by dissolving 15 mg of [6,6]-phenyl-C71-butyrate isomethyl ester in 1 ml of chlorobenzene (CB) and stirring overnight.

[0029] (5) Using a vacuum coating apparatus, deposit a 100 nm thick Ag electrode on the surface of the obtained electron transport layer.

[0030] Example 3: The difference between Example 3 and Example 2 is that in step (2), the amount of MeO-2PACz used is 100 μL and the concentration is 0.1 mg / mL; in step (3), the amount of perovskite precursor solution modified with fluorine formamidin perovskite single crystal is 60 μL; and in step (4), the electron transport layer precursor solution is 60 μL and the concentration is 25 mg / mL.

[0031] Example 4: The difference between Example 4 and Example 2 is that the amount of perovskite precursor solution modified with fluorine formamidinium-based perovskite single crystal in step (3) is 100 μL, and the amount of electron transport layer precursor solution in step (4) is 100 μL.

[0032] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that benzoamidine perovskite single crystal (BZ)2Pb1.5I4 was prepared by replacing p-fluorobenzoamidine hydrochloride with benzoamidine.

[0033] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that in step (3), an equal volume of perovskite precursor solution containing benzylamine perovskite single crystal (BZ)2Pb1.5I4 is used to replace the perovskite precursor solution containing p-fluorobenzylamine perovskite single crystal (TFBZ)PbI3.

[0034] Comparative Example 3: Using an equal volume of perovskite precursor solution (FA) without formamidinium-based single-crystal modification. 0.95 MA 0.05 Pb(I 0.95 Br 0.05)3 Spin coating is performed.

[0035] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that the perovskite precursor solution in step (3) contains 1 mg / mL, 3 mg / mL, 7 mg / mL and 9 mg / mL of p-fluorobenzomidine perovskite single crystals.

[0036] Comparative Example 5: The difference between Comparative Example 5 and Comparative Example 2 is that the perovskite precursor solution in step (3) contains formamidinium perovskite single crystals at concentrations of 1 mg / mL, 3 mg / mL, 7 mg / mL, and 9 mg / mL.

[0037] (1) The p-fluorobenzamide perovskite single crystal (TFBZ)PbI3 prepared in Example 1 and the benzamide perovskite single crystal (BZ)2Pb1.5I4 prepared in Comparative Example 1 were characterized by XRD, such as... Figure 1 The XRD results show that the characteristic diffraction peaks of single-crystal (TFBZ)PbI3 correspond to the (002) and (021) planes, while the diffraction of benzamide perovskite single-crystal (BZ)2Pb1.5I4 corresponds to the (200) plane, indicating that both materials have high crystallinity and structural consistency. Further analysis shows that both compounds are composed of [PbI6]. 4 The structure consists of a one-dimensional chain composed of octahedrons. The organic cation BZ⁺ is located along the b-axis of (BZ)₂Pb₁.₅I₄, while TFBZ⁺ is located in the voids created by (TFBZ)PbI₃ along the a-axis. The electron-attracted -CF₃ ligands of TFBZ promote the formation of the one-dimensional lead-iodine chain, exhibiting a shorter average Pb–I bond length (3.202 Å) and reduced interlayer spacing (4.543 Å), indicating enhanced coordination and packing density. In contrast, the BZ-based structure has a longer average Pb–I bond length (3.315 Å) and a larger interlayer spacing (4.564 Å). This suggests that (TFBZ)PbI₃ single crystals possess higher structural order and thermodynamic stability, which is more conducive to controlling the crystallization kinetics of the 3D perovskite covering it, promoting the formation of high-quality thin films, improving orientation, and reducing defect density, thereby enhancing device performance.

[0038] (2) The heterostructure and micromorphology of the one-dimensional / 3D perovskite hybrid films prepared in step (3) of Example 2 and Comparative Example 2 were characterized by HRTEM, respectively. Figure 2 As shown,

[0039] One-dimensional (TFBZ)PbI3 single crystals exhibit dominant structural characteristics in the (002) and (021) directions, while the three-dimensional perovskite phase (3D (100), d ≈ 6.3 Å) can simultaneously match two different sets of one-dimensional phase crystal planes, forming an 85.7° angle with the one-dimensional (021) plane and a 76.8° angle with the one-dimensional (002) plane, respectively. These multiple lattice-matching relationships provide more low-lattice-mismatch nucleation sites for the growth of the three-dimensional perovskite phase, thereby synergistically inducing and promoting more stable growth of the three-dimensional phase.

[0040] (3) The surface morphology of the one-dimensional / three-dimensional perovskite films prepared in Example 2 and Comparative Example 2 was observed using a scanning electron microscope (SEM). Figure 3 As shown in Figure a, compared with the control sample, the grain size of the BZ / PVK and TFBZ / PVK samples is significantly increased. The increased grain size effectively reduces the number and size of grain boundaries and voids, promotes light absorption, and lowers the defect density within the film. It also reduces the scattering and recombination of photogenerated carriers at grain boundaries and defects. Obvious one-dimensional structural features were observed on the surface of the BZ / PVK and TFBZ / PVK films, mainly distributed at the grain boundaries of the three-dimensional perovskite crystals. This indicates that the one-dimensional perovskite phase preferentially forms at grain boundaries, significantly improving the grain boundary defect density.

[0041] (4) Investigate the effect of perovskite single crystals of different concentrations on the crystallization of perovskite precursor solutions, such as Figure 4 The XRD results show that when the perovskite precursor solution contains 5 mg / mL of one-dimensional fluorobenzoamidine perovskite single crystal in step (3), its diffraction peak has the highest peak value, indicating that the more crystals with this crystal orientation, the better the crystallinity.

[0042] (5) The photoelectric properties of the perovskite solar cells prepared in Example 2, Comparative Example 2, and Comparative Example 3 were studied, and the results are as follows: Figure 5 The current density-voltage (JV) characteristics in Table 1 show that the PCE of the BZ / PVK device modified with benzamide perovskite single crystal (BZ)2Pb1.5I4 is 24.79%, and the VC is 24.79%. OC It is 1.17 V, J SC The efficiency was 25.35 mA / cm², and the power factor (FF) was 0.836; the PCE of the device fabricated in Comparative Example 3 was 23.8%, and the voltage drop was V. OC 1.15 V, J SC The efficiency was 25.12 mA / cm², and the open-circuit voltage (FF) was 0.824. Meanwhile, the TFBZ / PVK device based on fluorobenzamide perovskite single crystal (TFBZ) modified with PbI3 had a power conversion efficiency (PCE) of 25.54% and an open-circuit voltage (V0.05). OC The voltage is 1.18 V, and the short-circuit current density (J) is 1.18 V.SC The photoelectric efficiency is 25.47 mA / cm², and the fill factor (FF) is 0.85. This indicates that the unique biplane anchoring structure of (TFBZ)PbI3 effectively promotes lattice matching between the one-dimensional and three-dimensional phases, significantly improving its photoelectric properties.

[0043] (6) The photoelectric performance stability of the perovskite solar cells prepared in Example 2, Comparative Example 2, and Comparative Example 3 was studied, and the results are as follows: Figure 6 As shown in Table 1, the TFBZ / PVK device modified with fluorobenzamidinium perovskite single crystal (TFBZ) PbI3 maintained 90.13% of its initial PCE after being treated under specific environmental conditions (25°C, relative humidity 40±5%) for 1000 h, while the PCE of the control group decreased to 61.5%. This indicates that the TFBZ / PVK device modified with fluorobenzamidinium perovskite single crystal (TFBZ) PbI3 exhibits excellent stability.

[0044] Table 1 Performance Comparison of Perovskite Solar Cells

[0045] project Energy conversion efficiency (%) Performance stability (%) Example 2 25.54% 90.13% Comparative Example 2 24.79% 66.31% Comparative Example 3 23.80% 61.50%

[0046] In summary, this invention provides a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium-based perovskite single crystal modification. On one hand, it utilizes the strongly electron-attracting -CF3 groups in the fluorinated formamidinium-based single crystal to enhance molecular polarity; on the other hand, it stabilizes with [PbI6] through intramolecular interactions. 4 ⁻A one-dimensional framework structure with coordination. The one-dimensional fluorinated formamidinium-based perovskite single crystal matches the dual-anchored lattice of the three-dimensional perovskite through its plane (002) and plane (021), providing low-strain nucleation sites for the three-dimensional perovskite lattice and reducing defects. This effectively improves the crystallinity of the three-dimensional perovskite, increases the grain size, and more efficiently passivates lead / iodine vacancy defects. Thus, by significantly suppressing nonradiative recombination and extending carrier lifetime, this unique structure synergistically optimizes the quality and photoelectric performance of solar cell films, enabling perovskite solar cell devices to achieve an efficiency of 25.54%. Moreover, the unencapsulated device still maintains 90.13% of the initial efficiency after 1000 hours under environmental conditions, demonstrating excellent stability.

Claims

1. A method for fabricating a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification, characterized in that... Includes the following steps: (1) Select transparent conductive glass as substrate; (2) Spin-coat a hole transport layer on the substrate surface with a solution of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid; (3) Spin-coat a perovskite precursor solution containing a one-dimensional fluorinated formamidinium perovskite single crystal on the hole transport layer to obtain a perovskite film; (4) Drop an electron transport layer precursor solution onto the surface of the perovskite film and spin-coat an electron transport layer; then spin-coat a solution of 2,9-dimethyl-4,7-biphenyl-1,10-o-diazaphenanthroline on the surface of the electron transport layer; (5) Prepare a metal electrode.

2. The method for preparing a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification according to claim 1, characterized in that, The perovskite precursor solution contains 5-9 mg / mL of one-dimensional fluorinated formamidinium perovskite single crystals.

3. The method for preparing a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification according to claim 1, characterized in that, The amount of perovskite precursor solution used for the fluorinated formamidinium-based perovskite single crystal is 60-100 μL, and the perovskite precursor solution contains 5 mg / mL of one-dimensional fluorinated formamidinium-based perovskite single crystal.

4. The method for preparing a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification according to claim 1, characterized in that, The one-dimensional fluorinated formamidine single crystal is prepared by the following method: p-fluorobenzamide hydrochloride and PbI2 are dissolved in an acidic solution, heated and stirred until completely dissolved, then cooled to room temperature to precipitate single crystals, and then washed, filtered and dried to obtain the crystals.

5. The method for preparing a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification according to claim 4, characterized in that, The mass ratio of benzamide hydrochloride to PbI2 is 1:

1.

6. The method for preparing a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification according to claim 4, characterized in that, The volume ratio of HI to HPO3 in the acidic solution is 5:

1.

7. The method for preparing a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification according to claim 1, characterized in that, In step (2), the amount of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACz) solution used is 60-100 μL, and the concentration is 0.1-1 mg / mL.

8. The method for preparing a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification according to claim 1, characterized in that, In step (4), the amount of electron transport layer precursor solution used is 80-100 μL, and the concentration is 15-25 mg / mL.

9. The method for preparing a high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification according to claim 1, characterized in that, In step (4), the electron transport layer precursor solution is prepared by dissolving isomethyl [6,6]-phenyl-C71-butyrate in chlorobenzene.

10. A high-efficiency and stable perovskite solar cell based on one-dimensional fluorinated formamidinium single crystal modification, prepared by the method according to any one of claims 1-9.

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