Perovskite active layer passivation agent, perovskite solar cell and preparation method

Abstract

This invention discloses a perovskite active layer passivating agent, a perovskite solar cell, and a preparation method thereof, relating to the field of perovskite solar cell technology. The invention uses a combination of formamidine thiocyanate (FASCN) and dodecyl ammonium bromide (DABr) as passivating agents. Through the "phase screening" effect of FA⁺ and the coordination regulation of SCN⁻, n=3 single-phase quasi-two-dimensional perovskite is selectively generated on the wide-bandgap perovskite surface, completely suppressing the n=2 phase and eliminating multiphase energy level disorder. Simultaneously, it achieves triple synergistic passivation: SCN⁻ coordinates and passivates lead defects, Br⁻ fills halogen vacancies, and FA⁺ occupies A-site vacancies, resulting in a 27% reduction in trap density and a 12-fold increase in carrier lifetime. The resulting perovskite solar cell exhibits a 6.8% increase in efficiency, significantly enhanced thermal stability, and a 4-fold increase in T80 lifetime. Furthermore, it is fully compatible with existing preparation processes and suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, and particularly relates to a perovskite active layer passivating agent, a perovskite solar cell, and a preparation method thereof. Background Technology

[0002] Perovskite solar cells are a novel third-generation photovoltaic technology. Their core light-absorbing layer utilizes an organic-inorganic hybrid material with a perovskite crystal structure, possessing the general chemical formula ABX3. Here, the A-site is a monovalent organic cation (such as formamidinium FA). + methylammonium (MA) + ) or inorganic cations (such as Cs) + The B site is a divalent metal cation (mainly Pb). 2+ The X-position is a monovalent halide anion (I). - ,Br - Cl - (or a mixture thereof). A typical perovskite solar cell employs a sandwich structure: a conductive glass substrate / hole transport layer / perovskite light-absorbing layer / electron transport layer / metal electrode. When sunlight shines on the cell, the perovskite layer absorbs photons and generates excitons (electron-hole pairs). These excitons rapidly dissociate into free carriers, and electrons and holes migrate to the electron transport layer and hole transport layer, respectively, ultimately being collected by the electrodes to form a photocurrent. By adjusting the halogen composition (e.g., increasing the Br⁻ ratio), the bandgap of perovskite can be broadened from the conventional 1.5 eV (MAPbI₃) to 1.6-1.8 eV. Wide bandgap perovskite with a bandgap of approximately 1.68 eV is an ideal top-cell material for constructing tandem solar cells: when tandem with silicon cells (bandgap 1.12 eV), the theoretical efficiency can reach 43%; when tandem with narrow bandgap perovskite (bandgap 1.2 eV), the theoretical efficiency can reach 45%.

[0003] Quasi-two-dimensional perovskites are perovskites with large-volume organic spacer cations (such as phenylethylamine PEA) inserted into a three-dimensional perovskite structure. + , butylamine BA + Dodecylamine (DA) + The layered structure formed by (etc.) has the general chemical formula (RNH3)2A n-1 B n X 3n+1Compared to 3D perovskites, Q-2D perovskites offer the following advantages: a hydrophobic organic layer blocks water and oxygen permeation, enhancing environmental stability; hydrogen bonds and van der Waals forces strengthen lattice rigidity, suppressing ion migration; and the quantum confinement effect allows for tunable band gaps, optimizing energy level matching. In Q-2D perovskites, the n-value represents the number of inorganic layers. Different n-values ​​correspond to different degrees of quantum confinement and photoelectric properties: n=1: pure two-dimensional phase, with the largest band gap (approximately 2.5 eV) and strongest insulation; n=2: two inorganic layers, with a band gap of approximately 2.2 eV; n=3: three inorganic layers, with a band gap of approximately 2.0 eV; n=∞: three-dimensional perovskite, with a band gap of approximately 1.6 eV. When multiple n-value phases coexist, an "energy funnel" effect occurs: charge carriers generated by high-energy photons are generated in the high-n phase and may be lost through recombination at the intermediate phase interface during transfer to the low-n phase. Therefore, achieving a single n-phase or a controllable phase distribution is crucial for improving device performance.

[0004] In existing technologies, Zhao et al. (Adv. Mater. 2021, 33, 2007460) and Jung et al. (Adv. Energy Mater. 2019, 9, 1901872) used a single organic ammonium salt to treat perovskite films. However, due to the complex reaction kinetics, multiple phases (n=1, 2, 3...) coexist in this system, making it difficult to achieve selective growth of a single phase; there is a lack of means to control the crystal growth direction, resulting in a large number of crystals with horizontal orientation, which hinders charge transport; it can only provide halide ions to fill vacancies and cannot effectively passivate lead defects; under high temperature or long-term light exposure, the modified layer itself may decompose or undergo ion migration. Summary of the Invention

[0005] In the field of wide-bandgap perovskite solar cells (PSCs), quasi-two-dimensional (Q-2D) structure design is an effective strategy to improve device stability. The basic principle is to introduce bulky organic spacer cations (such as alkylammonium ions, aromatic ammonium ions, etc.) into the three-dimensional perovskite lattice. These organic cations interact with inorganic [PbI6]. 4- The octahedral layers are stacked alternately to form a layered structure. Because the organic spacer layer is hydrophobic, it can effectively prevent water and oxygen molecules from penetrating into the perovskite lattice. At the same time, the hydrogen bonds (such as N−H···I) and weak van der Waals forces formed between the organic and inorganic components can enhance the overall stability of the lattice and inhibit ion migration.

[0006] To address the problems of low phase purity, disordered crystal orientation, insufficient defect passivation, and poor thermal stability in existing single organic ammonium salt post-processing technologies, this invention provides a perovskite active layer passivating agent and a method for passivating perovskite solar cells.

[0007] This invention proposes a "synergistic co-modification" strategy, which uses a combination of formamidinium thiocyanate (FASCN) and dodecyl ammonium bromide (DABr) to achieve precise phase control and deep defect passivation on the surface of wide-bandgap perovskite thin films.

[0008] In a first aspect, the present invention provides a perovskite thin film passivating agent, characterized in that it comprises formamidinium thiocyanate (FASCN), dodecyl ammonium bromide (DABr), and a solvent.

[0009] In some embodiments, the mass ratio of formamidinium thiocyanate (FASCN) to dodecyl ammonium bromide (DABr) is (15-25):1, preferably 20:1. Too low a FASCN ratio cannot completely suppress the n=2 phase, while too high a FASCN ratio will corrode the perovskite matrix.

[0010] In some embodiments, the concentrations of formamidinium thiocyanate (FASCN) and dodecyl ammonium bromide (DABr) in the passivating agent are 2.5 mg / mL-7.5 mg / mL and 0.1 mg / mL-0.5 mg / mL, respectively, preferably 5 mg / mL and 0.25 mg / mL.

[0011] A second aspect of the present invention provides a method for preparing a perovskite thin film passivating agent: Step 1: Dissolve dodecyl ammonium bromide (DABr) in a solvent and stir to prepare a DABr mother liquor. Preferably, the mother liquor can be stored at 4°C in the dark and should be brought to room temperature before use.

[0012] Step 2: Dissolve formamidinium thiocyanate (FASCN) in a solvent and stir to prepare a FASCN stock solution. This solution must be prepared fresh for use to avoid SCN contamination. - Oxidation.

[0013] Step 3: Add an appropriate amount of DABr stock solution to FASCN stock solution, and then add solvent to dilute.

[0014] In some embodiments, the mass ratio of DABr to FASCN is (15-25):1, preferably 20:1. Too low a FASCN ratio cannot completely suppress the n=2 phase, while too high a FASCN ratio will corrode the perovskite matrix.

[0015] In some embodiments, the concentrations of DABr and FASCN in the passivating agent are 2.5 mg / mL-7.5 mg / mL and 0.1 mg / mL-0.5 mg / mL, respectively, preferably 5 mg / mL and 0.25 mg / mL.

[0016] In some embodiments, the solvent is selected from one or more of chlorobenzene, isopropanol, toluene, ethyl acetate, etc. Preferably, the solvent is anhydrous isopropanol.

[0017] A third aspect of the present invention provides a method for using a perovskite thin film passivating agent, the specific steps of which are as follows: The substrate with the prepared perovskite active layer was fixed on a spin coater. After starting the spin, the passivating agent was added to the center of the rotating substrate. The spin was maintained to allow the solution to spread evenly and evaporate. Then, an annealing treatment was performed.

[0018] Preferably, the spin coating parameters are as follows: rotation speed: 4000 rpm (linear velocity of approximately 20-25 m / s, generating sufficient centrifugal force to ensure uniform spreading of the solution); time: 30 s (the first 10 s is the spreading stage, the middle 15 s is the solvent evaporation stage, and the last 5 s is the drying stage); solution volume: just enough to cover the substrate (30 μL for a 1.5 × 1.5 cm² substrate; excessive volume will cause the solution to be thrown out, while insufficient volume will result in uneven coverage); environment: nitrogen atmosphere glove box, water and oxygen content <1 ppm, temperature 20-25℃.

[0019] Preferably, a thermal annealing process is used, that is, after spin coating is completed, the substrate is immediately transferred to a 100°C hot stage and heated for 5-10 minutes.

[0020] The effect of annealing: to promote DA + FA + SCN - The reaction of ions with the perovskite surface causes the generated quasi-two-dimensional phase to recrystallize and form a vertical orientation; the residual solvent evaporates, improving the density of the film.

[0021] In a fourth aspect, the present invention provides a perovskite solar cell with interface passivation, wherein the cell uses the passivating agent provided in the first aspect of the present invention and the perovskite active layer is passivated according to the passivation method provided in the third aspect of the present invention.

[0022] The perovskite system to which this invention is applicable: excluding FA 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3 and FA 0.8 Cs 0.2 Pb(I 0.6 Br 0.4 In addition to 3, it can be extended to other mixed cationic wide-bandgap perovskites containing formamidinium, cesium, and methylammonium.

[0023] Preferably, the perovskite solar cell provided by the present invention has a nip-type structure, comprising, from bottom to top: 1. Substrate: FTO conductive glass (fluorine-doped tin oxide, sheet resistance 15-20 Ω / sq); 2. Hole transport layer: 4-PADCB ([4-(7H-dibenzo[c,g]carbazole-7-yl)butyl]phosphonic acid), thickness approximately 10-20 nm; 3. Perovskite active layer: FA 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3 or FA 0.8 Cs 0.2 Pb(I 0.6 Br 0.4 3. Band gap approximately 1.68 eV, thickness approximately 500-800 nm; 4. Interface modification layer: DABr+FASCN synergistic passivation layer, forming an n=3 single-phase quasi-two-dimensional perovskite ( ), with a thickness of approximately 10-30 nm; 5. Electron transport layer: C 60 6. Hole blocking layer: BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), with a thickness of about 8-12 nm; 7. Metal electrode: Ag (silver), with a thickness of about 100 nm.

[0024] The method for fabricating the perovskite solar cell with interface passivation is as follows: Prepare perovskite precursor solution.

[0025] Pretreatment of FTO conductive glass substrate.

[0026] Preparation of hole transport layer.

[0027] Preparation of perovskite active layer.

[0028] Preparation of interface passivation modification layer.

[0029] Fabrication of electron transport layer and Ag electrode.

[0030] The (5) interface passivation modification layer is prepared by using the passivating agent provided in the first aspect of this invention and the passivation method provided in the third aspect of this invention to passivate the perovskite active layer and form an interface passivation modification layer on the perovskite active layer.

[0031] This invention achieves precise control of phase purity by selectively promoting the growth of a single n=3 phase and completely suppressing the n=2 phase through the "phase screening" effect of FA⁺, thus eliminating energy level disorder caused by multiphase coexistence; it also optimizes crystal growth kinetics, making inorganic [PbI6]... 4-The layers are arranged perpendicular to the substrate to create efficient out-of-plane charge transport channels; through SCN - With Pb 2+ Coordination passivation of lead defects, Br - Filling iodine vacancies, FA + Occupying the A-site defect, a triple synergistic passivation is achieved. The perovskite solar cell prepared by this invention exhibits enhanced thermal stability and SCN... - Its strong coordination effect stabilizes the crystal lattice and inhibits I / Br phase separation and ion migration.

[0032] The core innovation of this invention lies in DA + With SCN - The synergistic mechanism includes the following four aspects: Mechanism 1: Phase selection effect – achieving precise growth of a single phase with n=3 phases When DABr exists alone, DA + Reaction with PbI2 on the perovskite surface: (Initial product of phase n=1) then reacts with 3D perovskite: (n=2 phases) or (n=3 phase) Due to uncontrollable reaction kinetics, phases with n=2 and n=3 are generated simultaneously. When FASCN is introduced, FA... + and SCN - Play a "phase screening" role: FA + Provides additional formamidinium cations, according to the quasi-two-dimensional perovskite stoichiometry. From n=2 ( ) To n=3 ( The transformation requires more financial analysis (FA). + SCN - With Pb 2+ Its coordination ability (stability constant log K≈3.5) is stronger than that of I. - and Br - Prioritize occupying Pb 2+ Coordination sites, altering reaction pathways; SCN - Linear structure (S=C=N) - ) to enable insertion Between the octahedrons, the longitudinal growth of layered structures is promoted. Overall effect: the reaction system tilts towards the thermodynamically more stable n=3 phase, while the n=2 phase is completely suppressed. PL spectroscopy shows that the n=2 phase emission peak at 510 nm completely disappears in the DABr+FASCN treated sample, retaining only the characteristic emission of the n=3 phase at 570 nm.

[0033] Mechanism 2: Triple Defect Passivation – Comprehensive Elimination of Three Main Defects on the Non-Radiative Recombination Center Perovskite Surface. This invention provides a triple passivation mechanism: (1) Lead Defect Passivation (Pb0 Or PbI inversion defect): SCN - The S atom in the Pb atom has a lone pair of electrons, which can coordinate with the unsaturated Pb atom. 2+ A coordinate bond (Pb-SCN) is formed. SCN - Its coordination ability is stronger than that of I - and Br - It can effectively occupy Pb 2+ The vacancy prevents it from being reduced to metallic Pb. 0 XPS showed that the binding energy of Pb 4f7 / 2 decreased from 138.30 eV to 138.20 eV after DABr+FASCN treatment, indicating that the electron cloud density of Pb increased and the coordination environment improved. (2) Halogen vacancy passivation (V_I or V_Br): DABr provides Br⁻ to fill iodine vacancies. The ionic radius of Br⁻ (196 pm) is smaller than that of I. - (220 pm), which can shrink the lattice, enhance the strength of Pb-X-Pb bonds, and inhibit halide ion migration. (3) A-site defect passivation (V_FA or V_MA): FASCN provides FA + It occupies the A-site cation vacancy. FA + The ionic radius (253 pm) and MA + (217 pm) and Cs + (167 pm) matching can stabilize the perovskite lattice and suppress vacancy-assisted ion migration.

[0034] Mechanism 3: Energy Level Optimization and Interface Dipole – Promoting Efficient Charge Extraction. The energy level positions of the n=3 single-phase quasi-two-dimensional perovskite are: conduction band bottom approximately -3.4 eV, valence band top approximately -5.4 eV (relative to the vacuum level). Compared to 3D perovskite (conduction band bottom -3.9 eV, valence band top -5.5 eV), the n=3 phase has a shallower conduction band and a deeper valence band, forming a Type-I energy level arrangement. For electrons: the n=3 phase acts as an electron transport channel; electrons injected from the 3D phase into the n=3 phase then... 60 Electron transport layer transport; for holes: the n=3 phase acts as a hole blocking layer, preventing holes from migrating to the electron transport layer and reducing interfacial recombination. KPFM measurements show that after DABr+FASCN treatment, the surface contact potential difference (CPD) increased from approximately -0.3 V in the control group to -0.1 V, indicating an upward shift of the surface Fermi level and a decrease in the work function, which is beneficial for electron extraction.

[0035] Mechanism 4: Enhanced Thermal Stability – Suppressing I / Br Phase Separation. In wide-bandgap perovskites, I⁻ and Br⁻ readily migrate and separate at high temperatures, forming I-rich and Br-rich phases, leading to bandgap changes and performance degradation. (SCN) - This process is inhibited through the following mechanisms: SCN⁻ and Pb2+ The strong coordination effect of SCN fixes the Pb²⁺ sites and reduces halogen vacancies; - The linear structure fills the lattice interstices, hindering the migration channels of halide ions; FA + The large-size cation effect stabilizes the lattice and increases the activation energy barrier. In-situ PL spectroscopy shows that during continuous annealing at 100°C for 30 minutes, the main peak of the DABr+FABr treated sample red-shifted from 750 nm to 765 nm (a sign of I / Br phase separation), while the peak position of the DABr+FASCN treated sample remained stable without red-shift.

[0036] The beneficial effects of this invention are as follows: (1) Advantage of precise phase purity control: through FA + With SCN - The "phase screening" effect enables the epitaxial growth of a single phase with n=3, and the PL spectrum shows that the n=2 phase (510 nm emission peak) completely disappears, while existing technologies cannot achieve selective growth of a single phase.

[0037] (2) Advantage in defect passivation depth: Existing technologies can only provide a single passivation mechanism (such as Br⁻ filling vacancies), while this invention achieves SCN - Coordination, Br - Gap filling, FA + The triple synergistic passivation of the site reduces the trap density by 27% and extends the carrier lifetime by 12 times, while existing technologies typically only extend it by 2-3 times.

[0038] (3) Thermal stability advantage: Devices processed by existing technologies are prone to I / Br phase separation (PL peak red shift) at high temperatures. This invention achieves phase separation without phase separation through the coordination stabilization effect of SCN⁻, and the T80 life is increased by 4 times, while existing technologies typically increase it by 1-2 times.

[0039] (4) Advantage of simple process: The present invention only requires replacing the post-treatment solution in the existing process, without changing the equipment or adding steps. It is fully compatible with the existing perovskite preparation process and is suitable for large-scale production.

[0040] (5) Advantages of synergistic improvement in efficiency and stability: Existing technologies often face the trade-off between efficiency and stability, that is, improving efficiency at the expense of stability or vice versa. This invention achieves a 6.8% increase in efficiency and a 4-fold increase in stability at the same time, breaking the bottleneck of traditional trade-offs. Attached Figure Description

[0041] The invention will now be described in more detail with reference to embodiments and the accompanying drawings. Figure 1The diagrams shown are schematic diagrams of the device structures in Examples 1, 2, and 3, illustrating the complete structure and functional layers of a pin-type perovskite solar cell.

[0042] Figure 2 PL spectra of thin films treated with different ammonium salts: (a) PL spectra of different series of ammonium salts, with the DA series showing significantly higher PL intensity; (b) Magnified short-wavelength region of DA series ammonium salts (DAI, DABr, DACl) showing the best effect of DABr, displaying characteristic emission of n=2 (510 nm) and n=3 (570 nm) phases; (c) Comparison of PL spectra of DABr+FAX (X=I, Br, Cl) mixed salts, showing that DABr+FAX achieves n=3 single phase; (d) Quantitative comparison of PL intensity of DABr+FAY (Y=SCN, COOH, BF4).

[0043] Figure 3 (a) PLQY (photoluminescence quantum yield) plot and (b) TRPL (time-resolved photoluminescence) curve for untreated, DABr+FABr, and DABr+FASCN treated films.

[0044] Figure 4 In-situ PL spectra of DABr+FABr and DABr+FASCN treated films during annealing at 100°C show that the DABr+FABr sample exhibits I / Br phase separation (red shift of peak position), while the DABr+FASCN sample remains stable.

[0045] Figure 5 (a) XRD pattern and (b, c) GIWAXS two-dimensional scattering patterns show that the sample of the present invention has a vertical crystal orientation.

[0046] Figure 6 Static water contact angle photographs of untreated films, films treated with DABr+FABr, and films treated with DABr+FASCN.

[0047] Figure 7 Box plots of photovoltaic performance statistics for Control and Target devices: (a) Jsc, (b) Voc, (c) FF, (d) PCE, with 20 devices counted for each condition.

[0048] Figure 8 (a) JV curves (forward and reverse scans) and (b) steady-state output power tests (continuous measurement for 60 seconds at maximum power point voltage) for Control and Target devices.

[0049] Figure 9 The photostability test curves of the unpackaged device under nitrogen atmosphere and continuous sunlight exposure for one day are shown, with the T80 lifetime marked. Detailed Implementation

[0050] The invention will be described in more detail below with reference to the embodiments and the accompanying drawings, which will enable those skilled in the art to have a more complete understanding of the invention, but does not limit the invention in any way.

[0051] Example 1: A perovskite thin film passivating agent, the specific composition and preparation method of which are as follows: (1) Preparation of DABr stock solution: Weigh 100 mg DABr and dissolve it in 10 mL of anhydrous isopropanol. Stir at 60°C for 2 hours to prepare a 10 mg / mL stock solution. Store at 4°C in the dark. (2) FASCN stock solution: Weigh 10 mg FASCN and dissolve it in 10 mL of anhydrous isopropanol. Stir at room temperature for 1 hour to prepare a solution of 1 mg / mL. Prepare and use immediately. (3) Preparation of passivating agent: Take 1 mL of DABr stock solution (10 mg / mL) into a 2 mL glass bottle, add 500 μL of FASCN stock solution (1 mg / mL), and then add 500 μL of anhydrous isopropanol, with a final volume of 2 mL. Final concentration: DABr 5 mg / mL, FASCN 0.25 mg / mL, DABr:FASCN mass ratio 20:1.

[0052] Example 2: A method for passivating a perovskite active layer, the specific steps of which are as follows: (1) Dynamic spin coating: The substrate with the perovskite active layer film is fixed on the spin coater, the rotation speed is 4000 rpm, and 30 μL of the passivating agent prepared in Example 1 is added immediately after starting, and the spin coating is performed for 30 seconds; (2) Heat annealing: Anneal at 100℃ for 5-10 minutes to form a single-phase quasi-two-dimensional passivation layer with n=3.

[0053] Example 3: An interface-modified perovskite battery material, prepared by the following method: (1) Preparation of wide-bandgap perovskite precursor solution The concentration of the perovskite precursor solution used in this experiment was 1.5 mmol / mL. Taking the preparation of 2 mL solution as an example: weigh 528.5 mg lead iodide (PbI2, molecular weight 461.01 g / mol, purity 99%), weigh 209 mg formamidinium iodide (FAI, molecular weight 172.13 g / mol, purity 98%), weigh 25.5 mg methyl ammonium bromide (MABr, molecular weight 149.90 g / mol, purity 98%), weigh 19.8 mg cesium iodide (CsI, molecular weight 259.81 g / mol, purity 99.9%), and weigh 10 mg methyl ammonium chloride (MACl, molecular weight 67.52 g / mol, purity 98%, as an additive to promote crystallization).

[0054] The above solid raw materials were placed together in a 4 mL amber glass bottle, and 1.6 mL of N,N-dimethylformamide (DMF, anhydrous grade, 99.8% purity) and 0.4 mL of dimethyl sulfoxide (DMSO, anhydrous grade, 99.9% purity) were added, with a DMF:DMSO volume ratio of 4:1. A magnetic stir bar was added, and the mixture was stirred at room temperature for 3 hours until completely dissolved. Before use, the mixture was filtered through a PTFE membrane (0.22 μm pore size).

[0055] (2) Pretreatment of FTO conductive glass substrate a) Preliminary cleaning: Place the FTO conductive glass (size 15×15 mm², sheet resistance 20 Ω / sq, etched pattern of 8 mm wide electrode strip) in diluted dish soap water, and gently wipe with a lint-free cloth for 2-3 minutes to remove surface particles and organic residues. b) Ultrasonic cleaning: The substrate was placed in detergent water, deionized water, anhydrous ethanol and anhydrous ethanol in sequence, and ultrasonic cleaning was performed for 15 minutes in each step, with a power of 100 W and a frequency of 40 kHz. c) Storage: Immerse the cleaned substrate in anhydrous ethanol, seal and store, remove before use; d) Surface activation: Dry the substrate surface with high-purity nitrogen (99.999% purity), place it in an ultraviolet ozone cleaner with a UV lamp power of 15 W and an ozone concentration of about 50 ppm for 20 minutes to enhance the surface hydrophilicity (water contact angle <10°).

[0056] (3) Preparation of hole transport layer a) Dissolve 4-PADCB in anhydrous ethanol to a concentration of 0.5 mg / mL, and stir at 60°C for 2 hours until completely dissolved; b) Fix the pretreated FTO substrate onto a spin coater, set the rotation speed to 4000 rpm, and the time to 30 s; c) Use a pipette to add 30 μL of 4-PADCB solution to the center of the substrate, and immediately start spin coating; d) After spin coating, transfer the substrate to a 100°C hot stage and anneal for 10 minutes to form a dense self-assembled monolayer.

[0057] (4) Preparation of perovskite active layer (one-step antisolvent method) a) Fix the FTO / 4-PADCB substrate on the spin coater and set a two-step program: the first stage is 1000 rpm for 5 s; the second stage is 4000 rpm for 40 s. b) Start spin coating. Once the spin speed has stabilized, quickly use a pipette to add 50 μL of perovskite precursor solution to the center of the rotating substrate. c) At 30 seconds after the start of the second high-speed spin coating (i.e., with 10 seconds remaining), quickly use a pipette to add 160 μL of chlorobenzene (CB, anhydrous grade, 99.8% purity) to the center of the substrate as an anti-solvent to induce rapid crystallization; d) After spin coating, immediately transfer the substrate to a 100°C hot stage and anneal for 25 minutes to allow the residual solvent to fully evaporate and the lattice to rearrange, forming a black, mirror-gloss perovskite film.

[0058] (5) Preparation of interface passivation modification layer The perovskite film was passivated using the passivating agent prepared in Example 1 and the passivation method in Example 2 to obtain a perovskite active layer modified by interface passivation.

[0059] (6) Preparation of electron transport layer and Ag electrode The prepared perovskite film was transferred to a vacuum evaporation system (vacuum degree <5×10⁻⁶). -4 Pa), evaporated in sequence: C 60 Layer: 18 nm thick, deposition rate 0.2–0.4 Å / s, controlled temperature 350 °C; BCP layer: 10 nm thick, deposition rate 0.1–0.2 Å / s; Ag electrode: 100 nm thick, deposition rate 0.5–1.3 Å / s, effective area defined by a mask of 0.09 cm² (3 × 3 mm²). After deposition, the device was stored in a nitrogen glove box for testing.

[0060] Comparative Example 1: A perovskite solar cell without interface modification. Based on Example 3, this perovskite solar cell omits the interface passivation modification of the perovskite active layer. The preparation method of this perovskite solar cell is as follows: (1)-(4) Same as Example 3.

[0061] (5) The electron transport layer and Ag electrode were prepared in the same manner as in Example 3.

[0062] Comparative Example 2: Perovskite solar cells with interface modification using DABr+FABr, prepared by the following method: (1)-(4) Same as Example 3.

[0063] (5) Preparation of interface modification layer a) Preparation of stock solution: Weigh 100 mg DABr and dissolve it in 10 mL of anhydrous isopropanol, stir at 60°C for 2 hours to prepare a 10 mg / mL stock solution; Weigh 10 mg FABr and dissolve it in 10 mL of anhydrous isopropanol to prepare a 1 mg / mL solution. b) Preparation of working solution: Take 1 mL of DABr stock solution (10 mg / mL), add 500 μL of FABr solution (1 mg / mL), and then add 500 μL of anhydrous isopropanol to dilute. The final DABr concentration is 5 mg / mL and the FABr concentration is 0.25 mg / mL. c) Fix the FTO / 4-PADCB / perovskite substrate on the spin coater, set the rotation speed to 4000 rpm, and the time to 30 s; d) Add 30 μL of working solution to the rotating substrate, and anneal at 100℃ for 5-10 minutes after spin coating; (6) Preparation of electron transport layer and Ag electrode Same as Example 3.

[0064] Test Example 1 The performance of the perovskite solar cells prepared in Example 3 and Comparative Examples 1-2 was tested, and the test methods and results are compared as follows.

[0065] 1. JV curve test Tested using a Keithley 2400 source meter under an AM 1.5G standard solar simulator (light intensity 100 mW / cm²), at a scan rate of 100 mV / s, and a voltage range of -0.1 V to 1.3 V.

[0066] result: Example 3 (DABr+FASCN): Voc=1.255 V, Jsc=21.78 mA / cm², FF=84.67%, PCE=23.15%; Comparative Example 1: Voc = 1.216 V, Jsc = 21.32 mA / cm², FF = 83.58%, PCE = 21.67%; Comparative Example 2 (DABr+FABr): Voc=1.235 V, Jsc=21.45 mA / cm², FF=83.92%, PCE=22.18%.

[0067] 2. Stability Test Unpackaged devices were placed in a nitrogen glove box and continuously exposed to sunlight for one day, with JV curves tested periodically.

[0068] result: Example 3: T80 lifespan: approximately 800 hours; Comparative Example 1: T80 lifespan: approximately 200 hours; Comparative Example 2 T80 lifespan: approximately 350 hours.

[0069] 3. Carrier lifetime test (TRPL) The PicoQuant FluoTime 300 system was used, with an excitation wavelength of 507 nm and a probe wavelength of 750-770 nm.

[0070] result: Example 3: τ_ave = 359.92 ns; Comparative Example 1: τ_ave = 29.93 ns; Comparative Example 2: τ_ave = 270.14 ns.

[0071] In summary, by using the passivating agent described in this invention to passivate the perovskite active layer of the perovskite solar cell, the perovskite solar cell achieves the following technical effects.

[0072] Photoelectric conversion efficiency: increased from 21.67% in the control example to 23.15%, an absolute efficiency increase of 1.48 percentage points; Open-circuit voltage: increased from 1.216 V to 1.255 V; Short-circuit current density: increased from 21.32 mA / cm² to 21.78 mA / cm²; Fill factor: increased from 83.58% to 84.67%; Carrier lifetime: increased from 29.93 ns to 359.92 ns, a 12-fold increase; Stability and lifespan: The lifespan of the T80 has been extended from 200 hours to 800 hours, a 4-fold increase; Thermal stability: No I / Br phase separation was observed during annealing at 100°C for 30 minutes.

[0073] Test Example 2: PL spectra of perovskite films treated with different ammonium salts were tested.

[0074] The perovskite film structure was uniformly FTO / 4-PADCB / perovskite / ammonium salt, and the preparation method was the same as in Example 3. Isopropanol (IPA) was used as the solvent for the ammonium salt.

[0075] Test setup: A fluorescence spectrometer equipped with a continuous-wave laser source and a high-sensitivity CCD detector was used. Excitation conditions: A continuous-wave laser with a wavelength range of 405 nm was selected as the excitation source, the excitation power density was controlled within the range of 80-100 mW / cm², and the spot diameter was approximately 1-2 mm.

[0076] Sample preparation: Place the perovskite thin film sample to be tested on an FTO glass slide. The film thickness is usually 400–800 nm. Before testing, ensure that the sample surface is clean and free of mechanical damage.

[0077] Test procedure: Fix the sample on the sample stage and adjust the excitation light to be incident perpendicularly on the thin film surface; set the excitation wavelength and turn on the light source to preheat to a stable state; collect the fluorescence signal generated after the sample is excited, and the emitted light is dispersed by a monochromator. The scanning wavelength range is usually 600–850 nm (adjusted according to the perovskite composition); use a standard reference (such as a silicon photodiode or a standard fluorescent dye with known PLQY) to correct the spectral response; record the luminescence intensity-wavelength curve, with the vertical axis representing the relative luminescence intensity (unit: au, any unit) and the horizontal axis representing the wavelength (unit: nm) or photon energy (unit: eV).

[0078] Test environment: Routine tests are conducted at room temperature (25±2℃) in a nitrogen-protected glove box.

[0079] Test results are as follows Figure 2 As shown.

[0080] Figure 2 (a) PL spectra of perovskite films treated with different series of ammonium salts. The concentration of ammonium salts was 2 mg / ml. The DA series showed significantly higher PL intensity. Figure 2 (b) Using DA series ammonium salts (DAI, DABr, DACl), IPA solutions with a concentration of 4 mg / ml are used to show magnified images of the short-wavelength region where DABr has the best effect, and to show the characteristic emission of the n=2 (510 nm) and n=3 (570 nm) phases; Figure 2 (c) Comparison of PL spectra after treatment with a mixed salt of DABr+FAX (X=I, Br, Cl) (DABr is in 0.2 mg / ml IPA solution, FAX is in 4 mg / ml IPA solution), showing that n=3 single phases were achieved; Figure 2 (d) Quantitative comparison of PL intensity after treatment with DABr+FAY (Y=SCN, COOH, BF4) (DABr was treated with 0.2 mg / ml IPA solution, and FAY was treated with 4 mg / ml IPA solution).

[0081] Test Example 3: The PLQY and TRPL spectra of perovskite films treated with different passivating agents were tested.

[0082] The perovskite thin film structure is uniformly FTO / 4-PADCB / perovskite / passivating agent, and the preparation method is the same as in Example 3.

[0083] PLQY test details: Test principle: The absolute quantum yield measurement technique is adopted. The emission signal of the sample in all directions is collected by an integrating sphere. The number of photons absorbed and emitted by the sample are measured simultaneously. The ratio of the number of photons generated by radiative recombination to the number of incident photons is calculated, i.e., the PLQY value.

[0084] Test setup: An absolute PLQY spectrometer equipped with an integrating sphere was used. The integrating sphere has an inner diameter of 50-100 mm and its inner wall is coated with a polytetrafluoroethylene (PTFE) diffuse reflectance coating with a reflectance ≥98% (400–800 nm range).

[0085] Excitation conditions: Select a monochromatic or continuous wave laser with a wavelength range of 405 nm, an excitation bandwidth ≤ 10 nm, and an excitation power density controlled within the range of 0.01–10 mW / cm² to ensure that the excitation intensity is within the linear response range and to avoid the influence of carrier saturation or thermal effects.

[0086] Sample preparation: The perovskite thin film sample to be tested was fixed on an FTO glass slide with a film thickness of 200–800 nm and an effective luminescent area ≥0.1 cm². A blank substrate (FTO glass slide without a deposited film) was prepared simultaneously as a reference sample to subtract the substrate scattering and reflection background.

[0087] Test Procedure: Place the integrating sphere in the sample chamber, ensuring the optical path is sealed and free from ambient light interference. First, measure the emission spectrum (L_empty) of the blank substrate and record the spectral distribution of the excitation light after scattering by the substrate. Place the perovskite thin film sample at a designated position within the integrating sphere (center or back illumination mode), ensuring the excitation light completely covers the sample's luminescent area. Measure the emission spectrum (L_sample) of the sample, collecting samples in the range of 400–900 nm (adjusted according to the perovskite bandgap), with an integration time ≥1 s, repeating the measurement ≥3 times and taking the average. Simultaneously measure the incident spectrum (E) of the excitation source, determining the absolute photon flux using the sample shielding method or the standard reflector method. Record the integrated intensity of each spectrum and calculate the number of photons absorbed and emitted by the sample. Calculate the quantum yield.

[0088] Testing environment: Routine tests are conducted at room temperature (25±2℃) in a nitrogen-protected glove box (O2 < 0.1 ppm, H2O < 0.1 ppm) to avoid fluorescence quenching caused by oxygen and moisture. A control group can be set up to test stability under atmospheric conditions.

[0089] TRPL test details: Test setup: The system employs a time-correlated single photon counting (TCSPC) system, equipped with a pulsed laser source, a monochromator, and a high-sensitivity photomultiplier tube (PMT).

[0090] Excitation conditions: Use a picosecond pulsed laser with a wavelength range of 400–510 nm (405 nm is commonly used), a pulse width ≤100 ps, ​​a repetition rate of 1–10 MHz, and an excitation power density controlled at 0.1–10 nJ / cm² or 108 Within the range of –10¹¹photons / (pulse·cm²), ensure single-photon counting statistics and avoid multiphoton effects.

[0091] Sample preparation: The perovskite thin film sample to be tested is fixed on an FTO glass slide. The film thickness is 400–800 nm. Before testing, ensure that the sample surface is clean and free of mechanical damage. For environmentally sensitive perovskite materials, both sample preparation and testing are performed in a nitrogen-protected glove box or vacuum chamber.

[0092] Test Procedure: Place the sample on the sample stage and adjust the pulsed laser to excite the thin film surface at a 45° incident angle or perpendicular incident mode, with a spot diameter of approximately 0.5–2 mm; set the excitation wavelength and synchronously trigger the pulsed laser and TCSPC acquisition system, with the instrument response function (IRF) half-width typically ≤200 ps; collect the fluorescence decay signal generated after the sample is excited, and select a specific emission wavelength using a monochromator (usually within ±5 nm of the steady-state PL peak wavelength), setting the time window to 0–5000 ns and the number of time channels ≥4096; adjust the neutral density filter to control the probe light intensity, ensuring that the photon count rate is less than 1% of the excitation pulse repetition frequency to avoid the pile-up effect; record the fluorescence intensity decay curve over time, with the ordinate representing relative luminescence intensity (unit: au, any unit) and the abscissa representing time (unit: ns).

[0093] Testing environment: Routine tests are conducted at room temperature (25±2℃); for temperature dependence studies, a liquid nitrogen or liquid helium cryostat can be used, with a testing temperature range of 77–400 K. For atmosphere-sensitive perovskites, the entire process is conducted in a nitrogen atmosphere.

[0094] Test results are as follows Figure 3 , Figure 3 (a) PLQY (photoluminescence quantum yield) plot and (b) TRPL (time-resolved photoluminescence) curve for untreated films, films treated with DABr+FABr (DABr is 0.2 mg / ml IPA solution, FABr is 4 mg / ml IPA solution), and films treated with DABr+FASCN (DABr is 0.2 mg / ml IPA solution, FASCN is 4 mg / ml IPA solution).

[0095] Test Example 4: In-situ PL spectra of perovskite films after passivation during annealing at 100°C Test results are as follows Figure 4 , Figure 4In-situ PL spectra of films treated with 0.2 mg / ml DABr + 4 mg / ml FABr and 0.2 mg / ml DABr + 4 mg / ml FASCN during annealing at 100°C were obtained. The film structure was uniformly FTO / 4-PADCB / perovskite / ammonium salt, and the preparation method was the same as in Example 3. Isopropanol (IPA) was used as the solvent for the ammonium salt. The results showed that the DABr + FABr sample exhibited I / Br phase separation (red shift of the peak), while the DABr + FASCN sample remained stable.

[0096] Test Example 5: The perovskite thin film layer after passivation treatment exhibits a vertical crystal orientation. XRD test details: Test principle: Using Bragg's law of diffraction (2d sinθ = nλ), the relationship between the coherent scattering intensity of X-rays on the perovskite thin film crystal plane family and the diffraction angle is measured to obtain information such as crystal structure, phase composition, lattice parameters and crystal orientation.

[0097] Test setup: An X-ray diffractometer was used. The X-ray source was a Cu Kα target (λ = 1.5406 Å or 0.15406 nm), with an operating voltage of 40–45 kV and an operating current of 30–40 mA. A graphite monochromator or a parallel light optical system was used to eliminate Kβ radiation and fluorescence background.

[0098] Sample preparation: The perovskite film to be tested was deposited on an FTO conductive substrate with a film thickness of 400–800 nm and an effective test area ≥1 cm × 1 cm. The sample surface was smooth, free of cracks and obvious pores, and loose particles were removed by purging with nitrogen before testing.

[0099] Test procedure: Fix the sample on the sample stage, adjust the thin film surface to coincide with the geometric center of the diffractometer, and the height error ≤ ±0.1 mm; set the linkage scanning relationship (1:2 coupling) between the X-ray incident angle θ and the detector receiving angle 2θ; the scanning range is usually set to 2θ = 10°–60°, covering the typical diffraction peaks of perovskite (such as the (100) peak ~14.1°, (110) peak ~20.0°, (111) peak ~24.5°, (200) peak ~28.4°, (211) peak ~31.8° of FAPbI3). The step angle is 0.01–0.02°, and the dwell time per step is 0.5–2 s to ensure a signal-to-noise ratio ≥100:1. Record the curve of diffraction intensity (counts) as a function of the 2θ angle. The vertical axis is the diffraction intensity (unit: au or counts), and the horizontal axis is the diffraction angle 2θ (unit: °) or interplanar spacing d (unit: Å, converted from the Bragg equation).

[0100] Test results are as follows Figure 5 , Figure 5 (a) XRD pattern and (b, c) GIWAXS two-dimensional scattering plots show that the perovskite thin film layer of FTO / 4-PADCB / perovskite / 0.2 mg / ml DABr+4 mg / ml FASCN has a vertical crystal orientation.

[0101] Test Example 6: Testing the static water contact state of the perovskite thin film after passivation treatment. Testing apparatus: An optical contact angle measuring instrument is used. It is equipped with a high-precision micro-injection pump (resolution ≤0.1 μL), a monochrome LED or fiber optic light source, a high-speed CCD / CMOS camera (frame rate ≥30 fps, resolution ≥1280×1024 pixels), and image analysis software based on Young-Laplace fitting or tangent method.

[0102] Liquids and consumables: Ultrapure deionized water is used, with a single test droplet volume of 2–5 μL. The needle is a flat-tipped polytetrafluoroethylene needle to prevent asymmetric droplet detachment during droplet suspension.

[0103] Sample preparation: The perovskite film to be tested is deposited on a single-crystal silicon wafer, quartz glass, or FTO / ITO conductive substrate. The film thickness is 200–800 nm, and the effective test area is ≥1 cm × 1 cm. Before testing, the sample is equilibrated at 25±2℃ and 40–60% relative humidity for ≥30 min to eliminate the influence of residual solvents and thermal history from the preparation process. The surface is free of visible scratches, contaminants, or touch marks.

[0104] Test procedure: Fix the sample horizontally on the sample stage, ensuring that the parallelism error between the film surface and the horizontal plane is ≤ ±0.5°; adjust the camera focal length and light source angle to make the droplet outline clear, the background uniform, and the contrast between light and dark ≥ 50%; A micro-injection pump dispenses droplets at a rate of 0.5–2 μL / s, with the needle tip positioned 2–5 mm above the film surface. The droplets are transferred to the film surface either by free fall or by gentle contact, avoiding vibration caused by the needle touching the droplets. The droplet stabilization time is controlled within 10–60 s, and extended to 60–120 s for highly hydrophobic surfaces (WCA > 90°) to ensure that the liquid-solid interface reaches equilibrium. The droplet side profile image is acquired using the seated drop method, with the acquisition triggered at t = 15 s after droplet transfer. Image analysis software automatically fits the droplet profile curve and calculates the average of the contact angles on both sides.

[0105] Test results are as follows Figure 6 . Figure 6 Static water contact angle photographs of untreated films, films treated with 0.2 mg / ml DABr + 4 mg / ml FABr, and films treated with 0.2 mg / ml DABr + 4 mg / ml FASCN, with IPA as the solvent.

[0106] Test Example 7: Photovoltaic Performance Test Test details: Test principle: Under standard solar simulator illumination, the current response of perovskite solar cells under different bias voltages is measured using an electrochemical workstation or source meter to obtain the current density-voltage (JV) curve, and the open-circuit voltage (V) is extracted. OC ), short-circuit current density (J SC Key performance parameters include fill factor (FF) and photoelectric conversion efficiency (PCE).

[0107] Testing setup: An AAA-grade solar simulator is used, equipped with a xenon lamp light source and an AM 1.5G filter. Spectral matching, uniformity, and instability are all ≤±2%. Electrical signal measurements are performed using a source measurement unit (SMU, such as a Keithley 2400 equivalent precision device), with current resolution ≤10 fA and voltage resolution ≤100 nV. The sample stage is equipped with a temperature control module (25±1℃) and a four-wire probe system.

[0108] Device structure: The test sample is a complete perovskite solar cell device with the structure of FTO conductive glass / hole transport layer (4-PADCB) / perovskite light-absorbing layer (thickness 400–800 nm) / electron transport layer (C60 / BCP) / metal electrode (Ag, thickness 80–100 nm). The effective illumination area is limited to 0.04 cm² by a mask, and the area measurement accuracy is ≤±1%.

[0109] Test Procedure: 1. Calibrate the solar simulator to 100 mW / cm² (1 sun) using a standard silicon reference cell, with a calibration deviation ≤ ±1%; 2. Place the device under test on the sample stage, ensuring the effective area of ​​the device is completely within the uniform light spot area, and equilibrate the temperature to 25±1℃; 3. Use a four-wire connection method, connecting the source force wire to the metal electrode and the sense wire to the nearest connection to eliminate voltage drop due to wire resistance; 4. Set the voltage scan range typically from -0.1 V to V+0.2 V (or −0.2 V to 1.3 V, adjusted according to the device's voltage), with a scan step ≤ 10 mV; Scan mode selection: Forward Scan: Scan from V to short circuit (or 0 V → V), scan rate 10–100 mV / s; Reverse Scan: Scan from short circuit to V (or V → 0 V), scan rate 10–100 mV / s; Steady-state measurement (SPO): Constant voltage scan at maximum power point (MPP) voltage, record steady-state current density; Before scanning, the device needs to be light-soaked: irradiated with 100 mW / cm² white light for 5–10 min to eliminate the hysteresis effect caused by ion migration; Record the JV curves under both light and dark conditions. The dark-state JV is used to evaluate the rectification characteristics and leakage current.

[0110] Test results are as follows Figure 7 . Figure 7 Box plots of photovoltaic performance statistics for Target devices without post-treatment (Control) and treated with IPA solution of 0.25 mg / ml DABr + 5 mg / ml FASCN (method as in Example 3): (a) Jsc, (b) Voc, (c) FF, (d) PCE, with 20 devices counted for each condition.

[0111] Test Example 8: Photovoltaic Performance Test The testing method is the same as in Test Example 7. The test results are as follows: Figure 8 .

[0112] Figure 8 (a) JV curves (forward and reverse scans) and (b) steady-state output power tests (continuously measured for 60 seconds at maximum power point voltage) for the Target device without post-treatment (Control) and treated with IPA solution of 0.25 mg / ml DABr + 5 mg / ml FASCN (same method as in Example 3).

[0113] Test Example 9: Light Stability Test Figure 9 The photostability test curves of the Target device (prepared in the same way as in Example 3) treated with IPA solution of 0.25 mg / ml DABr + 5 mg / ml FASCN under nitrogen atmosphere and continuous sunlight irradiation are shown, and the T80 lifetime is marked. A AAA-grade solar simulator (equipped with a xenon lamp and AM 1.5G filter, spectral matching degree ≤±2%) was used to conduct continuous light aging tests on perovskite solar cells under standard test conditions (light intensity 100 mW / cm², ambient temperature 25±2℃). Before the test, the devices underwent initial JV characteristic characterization (scan rate 50 mV / s, scan direction from short circuit to open circuit), recording the initial photoelectric conversion efficiency (PCE0), open-circuit voltage (VOC), short-circuit current density (JSC), and fill factor (FF). Devices with PCE0 deviation ≤±5% from the batch average were selected as test samples. The devices were fixed on a temperature-controlled sample stage and set to open-circuit state. The solar simulator was turned on for continuous irradiation. During the irradiation process, the irradiation was interrupted periodically (at 0 h, 1 h, 5 h, 10 h, 25 h, 50 h, 100 h, and every 50–100 h thereafter) for JV scanning to track performance degradation. The total test duration continued until the PCE dropped to 80% of its initial value (T). 80The device's lifespan was recorded throughout the entire process, including surface temperature and environmental parameters. Photostability was evaluated using normalized PCE retention rate (PCE(t) / PCE0×100%), and T was used as the metric. 80 Lifetime was used as a quantitative indicator, and steady-state efficiency (SPO) was obtained by using maximum power point tracking (MPPT) mode (applying a constant bias voltage VMPP and fine-tuning in real time to maintain maximum output power) to eliminate scan rate-dependent errors caused by ion migration. For environmentally sensitive perovskite systems, the entire test was conducted in a nitrogen-protected glove box (O2 < 0.1 ppm, H2O < 0.1 ppm) or in devices with hermetically sealed (glass / UV-cured adhesive / cover glass structure).

[0114] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A perovskite active layer passivating agent, characterized in that, The passivating agent includes: dodecyl ammonium bromide, formamidinium thiocyanate, and solvent.

2. The passivating agent as described in claim 1, characterized in that, The solvent is selected from any one or more of isopropanol, chlorobenzene, toluene, ethyl acetate, etc.

3. The method for preparing the perovskite active layer passivating agent according to any one of claims 1-2, characterized in that, Includes the following steps: Step 1: Dissolve dodecyl ammonium bromide (DABr) in a solvent and stir to prepare DABr mother liquor; preferably, the mother liquor can be stored at 4°C in the dark and brought to room temperature before use; Step 2: Dissolve formamidinium thiocyanate (FASCN) in a solvent and stir to prepare a FASCN mother liquor; preferably, this solution should be prepared and used immediately to avoid SCN contamination. - Oxidation; Step 3: Add an appropriate amount of DABr stock solution to FASCN stock solution, and then add solvent to dilute.

4. The method of using the perovskite active layer passivating agent according to any one of claims 1-2, comprising the following specific steps: The substrate with the prepared perovskite active layer is fixed on a spin coater. After starting the spin, the passivating agent is added to the center of the rotating substrate. The spin is maintained to allow the solution to spread evenly and evaporate, and then annealing is performed.

5. The method as described in claim 4, characterized in that, The rotation speed was 4000 rpm; the spin coating time was 30 s; the amount of solution used was just enough to cover the substrate; the process was carried out in a nitrogen atmosphere glove box with a water and oxygen content of <1 ppm and a temperature of 20-25℃.

6. The method as described in claim 4, characterized in that, The heat treatment method is preferably hot annealing, which involves heating on a hot table at 100°C for 5-10 minutes.

7. A perovskite solar cell, characterized in that, The perovskite active layer is passivated using the passivating agent as described in any one of claims 1-2 and the method as described in any one of claims 4-6.

8. The perovskite solar cell according to claim 7, characterized in that, The perovskite is a wide-bandgap perovskite containing one or more of formamidinium, cesium, or methylammonium.

9. The perovskite solar cell as described in claim 7 or 8, characterized in that, The perovskite is FA. 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3 and FA 0.8 Cs 0.2 Pb(I 0.6 Br 0.4 One or two of 3.

10. The method for preparing a perovskite solar cell according to claim 7, characterized in that, Includes the following steps: (1) Prepare perovskite precursor solution; (2) Pretreatment of FTO conductive glass substrate; (3) Preparation of hole transport layer; (4) Preparation of perovskite active layer; (5) Preparation of interface passivation modification layer; (6) Fabrication of electron transport layer and Ag electrode; The method for preparing the interface passivation modification layer is as follows: using the passivating agent as described in any one of claims 1-2, and following the method as described in any one of claims 4-6, an interface passivation modification layer is formed on the perovskite active layer.

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