An additive for regulating nanoclusters within perovskite grains and its application

Abstract

This invention relates to the field of perovskite solar cell technology, specifically disclosing an additive for regulating nanoclusters within perovskite grains and its application. The additive comprises electron-deficient quaternary ammonium groups and negatively charged sulfonic acid groups. The additive of this invention contains electron-deficient quaternary ammonium groups and negatively charged sulfonic acid groups, which coordinate with the coordinating cations and halide anions of the perovskite precursor. This coordination interaction controls the crystallization process and passivates grain boundaries, inhibiting the formation of nanoclusters within the grains. This achieves the chemical elimination of nanoclusters within the perovskite grains and suppresses non-radiative recombination, thereby regulating the microstructure of the perovskite thin film grains.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 794,315, filed April 24, 2025, which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to the field of perovskite solar cell technology, and in particular to an additive for regulating nanoclusters within perovskite grains and its application. Background Technology

[0003] Metal halide perovskites are a class of semiconductor materials with diverse compositions and crystal structures. The general chemical formula for a standard three-dimensional perovskite is ABX3, where A is a monovalent cation (such as cesium or an organic cation), B is usually a divalent coordinating cation (such as lead, tin, or germanium), and X is a halide anion. Studies have confirmed that ABX3-type perovskites are high-performance optoelectronic materials with long carrier diffusion lengths and tunable band gaps. These materials can also be prepared under mild conditions using solution methods, possessing the potential to revolutionize solar cells at low cost. Today, perovskite solar cells (PSCs) have become a mainstream photovoltaic technology that can rival traditional silicon-based photovoltaic technologies. Over the past decade, perovskite solar cells have achieved rapid progress in both power conversion efficiency (PCE) and stability.

[0004] Impurity modulation in perovskites is considered a key strategy for improving device performance, as impurities not only affect the transport of photogenerated carriers but also often induce material degradation. Most published research focuses on impurity phase modulation at grain boundaries (GBs) and heterojunction interfaces, regions whose characteristics are relatively easy to characterize; the grain interior is typically assumed to be a pure phase. However, due to the flexible nature of the perovskite lattice, various nanoscale heterogeneous impurity phases may exist within its grains.

[0005] The challenge in studying these intragranular impurities lies in their complete embedding within the perovskite crystal matrix, lacking obvious surface features. This makes them difficult to detect using conventional surface characterization techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Therefore, elucidating the microstructure of intragranular impurity phases, studying their limiting mechanisms on perovskite device performance, and regulating the formation of intragranular impurity phases are of great significance for advancing the nanoengineering of perovskite optoelectronics. Summary of the Invention

[0006] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, a first objective of the present invention is to provide an additive for regulating nanoclusters within perovskite grains. A second objective of the present invention is to provide the application of the additive for regulating nanoclusters within perovskite grains.

[0007] The inventive concept of this invention is as follows: This invention uses low-dose scanning transmission electron microscopy (STEM) to reveal and study the microstructure of impurity phases within perovskite grains, and provides additives that can regulate the impurity phases within perovskite grains, thereby regulating the microstructure within perovskite thin film grains and improving the performance and stability of perovskite solar cells.

[0008] To achieve the first objective mentioned above, the present invention provides the following technical solution: In a first aspect, the present invention provides an additive for regulating nanoclusters within perovskite grains, characterized in that the additive comprises electron-deficient quaternary ammonium groups and negatively charged sulfonic acid groups.

[0009] In this invention, the additive includes electron-deficient quaternary ammonium groups and negatively charged sulfonic acid groups, which have coordination interactions with the coordinating cations and halide anions of the perovskite precursor. This coordination interaction can control the crystallization process and passivate defects, thereby inhibiting the formation of nanoclusters within the perovskite grains.

[0010] Preferably, the additive is alkyl dimethyl propanesulfonate.

[0011] Preferably, the additive comprises at least one of 3-(N,N-dimethyldecylammonium)propanesulfonate, 3-(N,N-dimethyldodecylammonium)propanesulfonate, 3-(N,N-dimethylmyristylammonium)propanesulfonate, 3-(N,N-dimethylhexadecylammonium)propanesulfonate (3-(N,N-dimethylpalmitylammonio)-propane-sulfonate, and 3-(N,N-dimethylstearylammonium)propanesulfonate.

[0012] More preferably, the additive is NDPS. NDPS, possessing both negatively charged sulfonic acid groups and positively charged active quaternary ammonium groups, is an amphiphilic internal salt. It coordinates with coordinating cations and halide anions (including cation clusters in the precursor solution) in the perovskite precursor solution, enhancing the miscibility and dispersibility between components. It can also reduce the size of cation clusters and increase the density of nucleation sites. During crystallization, NDPS coordinates with these cation clusters and slows down the crystallization process, achieving a higher level of intracrystalline component homogeneity. This provides sufficient time for cations to mix thoroughly, thereby preventing cation segregation and the formation of cation segregation-induced nanoclusters within the perovskite grains.

[0013] To achieve the second objective mentioned above, the present invention provides the following technical solution: In a second aspect, the present invention provides a perovskite precursor solution, the perovskite precursor solution comprising the additives described in the first aspect.

[0014] Preferably, in the perovskite precursor solution, the molar ratio of the additive to the perovskite precursor is (0.001~0.02):1; more preferably, in the perovskite precursor solution, the molar ratio of the additive to the perovskite precursor is (0.001~0.015):1; even more preferably, in the perovskite precursor solution, the molar ratio of the additive to the perovskite precursor is (0.001~0.01):1.

[0015] Preferably, the concentration of the additive in the perovskite precursor solution is 0.5~2 mg / mL.

[0016] In some embodiments of the present invention, the concentration of the additive is 0.5 mg / mL, 0.8 mg / mL, 1.0 mg / mL, 1.2 mg / mL, 1.5 mg / mL, 1.7 mg / mL and 2.0 mg / mL.

[0017] Preferably, the concentration of the perovskite precursor in the perovskite precursor solution is 0.5~1.8 mol / L; more preferably, the concentration of the perovskite precursor in the perovskite precursor solution is 0.6~1.6 mol / L; even more preferably, the concentration of the perovskite precursor in the perovskite precursor solution is 0.8~1.4 mol / L.

[0018] Preferably, the solvent of the perovskite precursor solution includes dimethyl sulfoxide (DMSO) and / or N,N-dimethylformamide (DMF). More preferably, the solvent is a mixture of DMF and DMSO; even more preferably, the volume ratio of DMF to DMSO is 7:(0.5~3); and even more preferably, the volume ratio of DMF to DMSO is 7:(1~3).

[0019] Preferably, the perovskite precursor solution further includes a crystallization regulator; more preferably, the crystallization regulator includes at least one of methylammonium chloride (MACl) and formamidine acetate (FAAc); even more preferably, the crystallization regulator is MACl.

[0020] In some specific embodiments of the present invention, the perovskite precursor in the perovskite precursor solution is FA. 0.9 Cs 0.1 PbI3 or FA 0.8 Cs 0.2PbI3 is prepared by the following steps: formamidinium iodide (FAI), cesium iodide (CsI), and lead iodide (PbI2) are dissolved in a solvent in a stoichiometric ratio, wherein the solvent is a mixture of DMF and DMSO; then a crystallization regulator and the additives are added to obtain the perovskite precursor solution.

[0021] In some embodiments of the present invention, the precursor of the perovskite precursor solution is FA. 0.5 Cs 0.5 PbI3 is prepared by the following steps: FAI, CsI, and PbI2 are dissolved in DMSO in a stoichiometric ratio; then a crystallization regulator and the additives are added to obtain the perovskite precursor solution.

[0022] In some embodiments of the present invention, the perovskite precursor in the perovskite precursor solution is ((FA0.95Cs0.05)PbI3). 0.975 (MAPbBr3) 0.025 The perovskite precursor solution is prepared by the following steps: FAI, CsI, PbI2, and MAPbBr3 single crystals are dissolved in a solvent, specifically a mixture of DMF and DMSO, in a stoichiometric ratio; then, a crystallization regulator and additives are added to obtain the perovskite precursor solution. In some specific embodiments of the present invention, the MAPbBr3 single crystal is prepared by dissolving methyl bromide chloride (MABr) and lead bromide (PbBr2) in a 1:1 molar ratio in DMF solvent, followed by the addition of dichloromethane for precipitation, to obtain the MAPbBr3 single crystal.

[0023] Thirdly, the present invention provides a method for regulating nanoclusters within perovskite grains, the method comprising adding the additive described in the first aspect to a perovskite precursor solution.

[0024] Preferably, the nanoclusters comprise an A2BX4 structure, and the perovskite precursor comprises an ABX3 structure; wherein the A site is an organic cation and / or a cesium ion (Cs). + The B site is a coordinating cation, and the X site is a halide anion.

[0025] Preferably, the organic cation includes formamidinium ion (FA). + ) or methylamine ion (MA + ).

[0026] Preferably, the coordinating cation includes lead ions (Pb²⁺). + ), tin ions (Sn) 2+ germanium ions (Ge) 2+ At least one of the following; more preferably, the coordinating cation is Pb². + .

[0027] Preferably, the halide anion includes bromide ions (Br₂). - ), iodide ions (I - ), chloride ions (Cl) - At least one of the following; more preferably, the halide anion is I - .

[0028] Preferably, the area of ​​the nanoclusters is less than 20 square nanometers; more preferably, the area of ​​the nanoclusters is less than 18 square nanometers; and even more preferably, the area of ​​the nanoclusters is less than 16 square nanometers.

[0029] Preferably, the nanoclusters are (FA) x Cs 1-x )2PbI4, 0 < x < 1; More preferably, the nanoclusters are (FA 0.4 Cs 0.6 )2PbI4.

[0030] Preferably, the perovskite precursor comprises FA 0.9 Cs 0.1 PbI3, FA 0.8 Cs 0.2 PbI3, FA 0.5 Cs 0.5 PbI3, ((FA0.95Cs0.05)PbI3) 0.975 (MAPbBr3) 0.025 At least one of them.

[0031] Fourthly, the present invention provides a perovskite thin film formed from the perovskite precursor solution described in the second aspect.

[0032] Preferably, the perovskite film is prepared by the following steps: spin-coating the perovskite precursor solution described in the second aspect onto a substrate, followed by annealing to obtain the perovskite film.

[0033] Preferably, the volume of the perovskite precursor solution is 30-60 µL; more preferably, the volume of the perovskite precursor solution is 35-55 µL; and even more preferably, the volume of the perovskite precursor solution is 40-50 µL.

[0034] Preferably, the substrate comprises indium tin oxide (ITO) conductive glass; more preferably, an electron transport layer is deposited on the ITO conductive glass; and even more preferably, the electron transport layer comprises an indium tin oxide (SnO2) thin film.

[0035] Preferably, the spin coating speed is 500~6000 rpm; more preferably, the spin coating speed is 1000~5500 rpm; and even more preferably, the spin coating speed is 1000~5000 rpm.

[0036] Preferably, the spin coating time is 40-80s; more preferably, the spin coating time is 45-70s; and even more preferably, the spin coating time is 50-70s.

[0037] Preferably, the spin coating comprises multi-step spin coating; more preferably, an anti-solvent is added in the final spin coating step; and even more preferably, the anti-solvent comprises ethyl acetate and / or diethyl ether.

[0038] Preferably, the amount of antisolvent added is 400~1000µL; more preferably, the amount of antisolvent added is 500~900µL; and even more preferably, the amount of antisolvent added is 600~800µL.

[0039] Preferably, the annealing temperature is 100~150℃; more preferably, the annealing temperature is 100~140℃; even more preferably, the annealing temperature is 110~140℃.

[0040] Preferably, the annealing time is 20-80 min; more preferably, the annealing time is 25-70 min; even more preferably, the annealing time is 30-65 min.

[0041] Fifthly, the present invention provides a perovskite battery, the perovskite battery comprising the perovskite thin film described in the fourth aspect.

[0042] Preferably, the perovskite solar cell comprises a conductive substrate, an electron transport layer, a perovskite thin film, a hole transport layer, and an electrode layer stacked sequentially.

[0043] Preferably, the conductive substrate comprises ITO conductive glass.

[0044] Preferably, the material of the electron transport layer includes at least one of titanium dioxide (TiO2), tin dioxide (SnO2), zinc oxide (ZnO), and methyl [6,6]-phenyl-C61-butyrate (PCBM); more preferably, the material of the electron transport layer includes SnO2.

[0045] Preferably, the material of the hole transport layer includes 2,2',7,7'-tetratetra[n,n-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD) or polytriarylamine (PTAA).

[0046] In some embodiments of the present invention, when 2,2',7,7'-tetratetra[n,n-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene is used as the hole transport layer, bis(trifluoromethane) sulfonimide lithium salt and 4-tert-butylpyridine are also added.

[0047] In some embodiments of the present invention, when PTAA is used as the hole transport layer, tris(pentafluorophenyl)borane (TPFB) also needs to be added.

[0048] Preferably, the electrode layer is made of at least one of silver, gold, copper, and bismuth. More preferably, the electrode layer is made of gold.

[0049] In a sixth aspect, the present invention provides a photovoltaic module comprising the perovskite thin film described in the fourth aspect.

[0050] The present invention also provides a photovoltaic module, comprising the perovskite thin film described in the fourth aspect or the perovskite solar cell described in the fifth aspect.

[0051] The beneficial effects of this invention are: 1. This invention captures hidden nanoclusters within perovskite grains using low-dose scanning transmission electron microscopy and then regulates and eliminates these nanoclusters through the introduction of additives. The additives of this invention contain electron-deficient quaternary ammonium groups and negatively charged sulfonic acid groups, which coordinate with the coordinating cations and halide anions of the perovskite precursor. This coordination interaction controls the crystallization process and passivates grain boundaries, inhibiting the formation of nanoclusters, achieving chemical elimination of nanoclusters, suppressing non-radiative recombination, and regulating the microstructure of the perovskite film grains.

[0052] 2. After the additives of this invention eliminate nanoclusters in the perovskite, the average photoluminescence lifetime of the resulting perovskite film decreases from 61.81 ns to 9.79 ns, significantly suppressing nonradiative recombination and improving the stability of the perovskite film. Furthermore, the power conversion efficiency (PCE) of the perovskite solar cell after eliminating nanoclusters increases to 26.03%, and the T95 operating stability of the battery device exceeds 1000 hours. Attached Figure Description

[0053] Figure 1 For FA 0.5 Cs 0.5 Atomic structure of nanoclusters in PbI3 perovskite solar cells; Figure 1 a in the middle is FA 0.5 Cs 0.5 PbI3 perovskite devices along

[010] oAtomic resolution HAADF-STEM images of zone axes; Figure 1 Figure b is a schematic diagram of the experimental setup for STEM study of perovskite cross-sections; Figure 1 In the middle c, there are atomic resolution HAADF-STEM images of the defocus series acquired from the cross-sectional sample; Figure 1 In the middle, d~f represent the distances along

[010] . o

[001] o and

[100] o HAADF-STEM images of nanoclusters acquired along the zone axis and their corresponding fast Fourier transforms; Figure 1 In the diagram, g~i represent the drawn atomic structures of the nanoclusters along

[010] . o

[001] o and

[100] o Schematic diagram of projection along the zone axis ( Figure 1 The left image of g~i), corresponding to the simulated HAADF-STEM image ( Figure 1 (intermediate image of g~i) and electron diffraction pattern ( Figure 1 (The right side of g~i).

[0054] Figure 2 This is a magnified atomic resolution HAADF-STEM image of nanoclusters in perovskite solar cells. Figure 2 In the image, a~d are atomic resolution HAADF-STEM images of different regions of the perovskite grain.

[0055] Figure 3 This is an atomic model of nanoclusters.

[0056] Figure 4 Simulation results for nanocluster phases with different FA to Cs ratios; Figure 4 where a is (FA x Cs 1-x A series of image simulation results of nanocluster phases in 2PbI4 with different FA to Cs ratios; Figure 4 In Figure a, b represents the contour of the intensity line along the direction indicated by the arrow.

[0057] Figure 5 Simulated XRD patterns of γ-CsPbI3, Cs2PbI4, PbI2, δ-CsPbI3, and δ-FAPbI3.

[0058] Figure 6 For FA 0.8 Cs 0.2 Atomic resolution HAADF-STEM images of PbI3 perovskite samples; Figure 6 In the image, a and b are atomic resolution HAADF-STEM images of different regions of the perovskite grain.

[0059] Figure 7 For FA 0.9 Cs 0.1 Atomic resolution HAADF-STEM images of PbI3 perovskite samples; Figure 7 In the image, a and b are atomic resolution HAADF-STEM images of different regions of the perovskite grain.

[0060] Figure 8 Thermodynamic stability and electronic structure of nanoclusters in perovskite; Figure 8 In the middle, 'a' represents the FA directly prepared using STEM observation. 0.5 Cs 0.5 In-situ atomic-scale observation of PbI3 perovskite sample. Figure 8 Figure b shows the STEM observation of a FA0.5Cs0.5PbI3 perovskite sample after exposure to air at 50% relative humidity and 25℃ for 45 minutes. Figure 8 The insets in figures a and b are the corresponding FFT plots; Figure 8 c represents the formation energy of the perovskite mineral phase and the nanocluster phase, with cesium iodide and lead iodide as references; Figure 8 d represents the density of states and band arrangement of the perovskite mineral phase and the nanocluster phase; Figure 8 In the diagram, e~i represent the projected density of states at the perovskite-nanocluster interface I, the interface without vacancies, the partial charge density of defect states near the conduction band bottom at the interface without vacancies (0.0005 e / Bohr³), the spin-polarized projected density of states at the interface with one iodine vacancy, and the partial charge density of defect states generated by the iodine vacancy at the interface in the configuration with one iodine vacancy (0.0005 e / Bohr³). Figure 8 In the diagram, j~n represent the projected density of states at the perovskite-nanocluster interface II, the interface without vacancies, the partial charge density of defect states near the conduction band bottom of the interface without vacancies (0.0005 e / Bohr³), the spin-polarized projected density of states of the configuration with one iodine vacancy at the interface, and the partial charge density of defect states generated by the iodine vacancy in the configuration with one iodine vacancy at the interface (0.0005 e / Bohr³). Figure 8 In the diagram, o~s represent the projected density of states at the perovskite-nanocluster interface III, the interface without vacancies, the partial charge density of defect states near the conduction band bottom at the interface without vacancies (0.0005 e / Bohr³), the spin-polarized projected density of states at the interface with one iodine vacancy, and the partial charge density of defect states generated by the iodine vacancy at the interface in the configuration with one iodine vacancy (0.0005 e / Bohr³). Figure 8 Color designation in c, 8g, 8l, 8q, 8i, 8n, 8s: A+ , cyan; Pb² + gray; I - ,Purple; Figure 8 The dashed line in the e~s diagram corresponds to the Fermi level; Figure 8 The illustrations in e, 8j, and 8o are atomic models of the perovskite-nanocluster interface.

[0061] Figure 9 To make FA 0.5 Cs 0.5 HAADF-STEM image of PbI3 perovskite after one week of storage in vacuum packaging; Figure 9 a and b are FA 0.5 Cs 0.5 HAADF-STEM images of different regions of PbI3 perovskite. Figure 9 c, d, and e are respectively Figure 9 a and Figure 9 A magnified image of the local area shown in box b.

[0062] Figure 10 The phase diagram of the Cs-Pb-I ternary system calculated for DFT (a) and the schematic diagram of energy changes during the decomposition of the perovskite phase and the nanocluster phase (b).

[0063] Figure 11 for Figure 8 Partial charge density of occupied states near VBM at interface I shown in Figure e (0.0005 e / Bohr³).

[0064] Figure 12 for Figure 8 Partial charge density of occupied states near VBM at interface II shown in j (0.0005 e / Bohr³).

[0065] Figure 13 for Figure 8 Partial charge density of occupied states near VBM at interface III shown in o (0.0005 e / Bohr³).

[0066] Figure 14 The diagram shows the results related to the regulation of nanoclusters. Figure 14 In the middle, 'a' represents the GPA analysis of regions containing and without nanoclusters; Figure 14 In the middle b, FA contains 0, 0.5 mg / mL, and 1 mg / mL. 0.9 Cs 0.1 XPS spectra of Pb 4f and I 3d obtained from PbI3 thin films; Figure 14 c represents FA containing 0 and 1 mg / mL NDPS. 0.9 Cs 0.1GIXRD patterns of PbI3 thin films on the (012) crystal plane at different tilt angles. The dashed lines show the change of the (012) peak position with the tilt angle. Figure 14 d represents FA containing 2 mg / mL NDPS. 0.9 Cs 0.1 ADF-STEM image of the device with PbI3 thin film ( Figure 14 (d above figure) and the corresponding S-element EELS surface distribution results ( Figure 14 (See image below). Figure 14 Figure e is a schematic diagram illustrating the mechanism of NDPS-induced chemical elimination of nanoclusters.

[0067] Figure 15 The structure of the NDPS and the calculated electrostatic potential distribution are shown. Figure 15 In the diagram, a represents the structure of the NDPS, and b represents the calculated electrostatic potential distribution.

[0068] Figure 16 For containing 0 mg / mL NDPS ( Figure 16 a) Contains 0.5 mg / mL NDPS ( Figure 16 b) 1 mg / mL ( Figure 16 c) and 2 mg / mL NDPS ( Figure 16 d) FA 0.9 Cs 0.1 Scanning electron microscope image of PbI3 thin film. Figure 17 FA containing 0, 0.5 mg / mL, 1 mg / mL and 2 mg / mL NDPS 0.9 Cs 0.1 Grain size distribution of PbI3 thin films.

[0069] Figure 18 FA containing 0, 0.5 mg / mL, 1 mg / mL and 2 mg / mL NDPS 0.9 Cs 0.1 XRD pattern of PbI3 thin film.

[0070] Figure 19 For FA containing 0, 0.5 mg / mL, 1 mg / mL and 2 mg / mL NDPS 0.9 Cs 0.1 S 2p (PbI3 thin film obtained) Figure 19 a) and N 1s ( Figure 19 b) X-ray photoelectron spectroscopy.

[0071] Figure 20 For containing 0.5 mg / mL ( Figure 20 a) and 2 mg / mL NDPS ( Figure 20b) FA 0.9 Cs 0.1 GIXRD patterns of the (012) crystal plane of PbI3 thin film at different tilt angles. The dashed line shows the change of the (012) peak position with the tilt angle.

[0072] Figure 21 FA containing 1 mg / mL NDPS 0.5 Cs 0.5 PbI3 perovskite solar cells and FA containing 1 mg / mL NDPS 0.9 Cs 0.1 Atomic resolution HAADF-STEM image and geometric phase analysis diagram of PbI3 perovskite solar cells. Figure 21 In this context, 'a' and 'b' represent FA containing 1 mg / mL NDPS. 0.5 Cs 0.5 HAADF-STEM images of PbI3 perovskite solar cells in different regions, c and d represent FA containing 1 mg / mL NDPS. 0.9 Cs 0.1 HAADF-STEM images of PbI3 perovskite solar cells in different regions, e~h correspond to the geometric phase analysis of images shown in a~d respectively.

[0073] Figure 22 The influence of nanoclusters on the performance and stability of perovskite solar cells; Figure 22 In the middle, 'a' represents FA containing 0 and 1 mg / mL NDPS. 0.9 Cs 0.1 Time-resolved photoluminescence spectrum of PbI3 thin film; Figure 22 b represents the FA without NDPS. 0.9 Cs 0.1 Transient absorption spectrum of PbI3 thin film; Figure 22 c represents FA with 1 mg / mL NDPS added. 0.9 Cs 0.1 Transient absorption spectrum of PbI3 thin film; Figure 22 In the figure, d represents the JV curves of the control group (containing nanoclusters) and the experimental group (excluding nanoclusters) perovskite solar cells; Figure 22 In the middle, e represents the corresponding photoelectric conversion efficiency output of the two types of perovskite solar cells in the control group and the experimental group at the maximum power point; Figure 22 The figure in f represents the MPP tracking stability test of the control and experimental groups of perovskite solar cells based on the ISOS-L-11 protocol.

[0074] Figure 23 FA without NDPS 0.9 Cs 0.1PbI3 film and FA with 1 mg / mL NDPS 0.9 Cs 0.1 UV-Vis absorption spectra of PbI3 thin films as a function of storage time under laboratory conditions.

[0075] Figure 24 FA without NDPS 0.9 Cs 0.1 PbI3 film and FA with 1 mg / mL NDPS 0.9 Cs 0.1 The absorbance of PbI3 thin film changes with storage time.

[0076] Figure 25 The graph shows the photoelectric conversion efficiency statistics of the two types of perovskite solar cells in the control group and the experimental group (n=30 devices in each group).

[0077] Figure 26 The storage stability of the two perovskite solar cells in the control and experimental groups; Figure 26 In the figure, a and b are low-magnification HAADF-STEM images of the cross-sectional samples of the control group and the experimental group, respectively; c and d are atomic resolution HAADF-STEM images of the cross-sectional samples of the control group and the experimental group, respectively; e and f are geometric phase analyses of the images shown in c and d, respectively. Detailed Implementation

[0078] To enable those skilled in the art to more clearly understand this application, the present invention will be further described in detail below with reference to the accompanying drawings. In the description of the present invention, it should be noted that unless specific conditions are specified, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0079] The chemical raw materials used in this invention are as follows: Lead bromide (PbBr2, purity ≥99%), 4-tert-butylpyridine (TBP, purity 96%), lithium bis(trifluoromethanesulfonyl)imide (purity 99.95%), N,N-dimethylformamide (DMF, purity 99.8%), dimethyl sulfoxide (DMSO, purity 99.9%), chlorobenzene (CB, purity 99.8%), toluene (TB, purity 99.8%), acetonitrile (CH3CN, purity >99.9%), diethyl ether (DE, purity 99%), and ethyl acetate (EA, purity 99.8%) were purchased from Merck, USA. Lead iodide (PbI2, purity >99%) and 3-(N,N-dimethylhexadecylammonium)propanesulfonate (purity >98%) were purchased from THIYI, Japan. Formamidinium bromide, NH2CH=NH2Br (FABr, purity >99.99%), formamidinium iodide, NH2CH=NH2I (FAI, purity >99.99%), methylammonium chloride, CH3NH3Cl (MACl, purity >99.99%), methylbromochloride, CH3NH3Br (MABr, purity >99.99%), and methylamine iodide, CH3NH3I (MAI, purity >99.99%) were purchased from Greatcell Solar, Australia. Tin dioxide (SnO2, 15% by weight in water dispersion), polytriarylamine (PTAA, average weight-average molecular weight 15,000–20,000), tris(pentafluorophenyl)borane (TPFB, 99% purity) and cesium iodide (CsI, 99.998% purity) were purchased from Alfa Esa, USA. 2,2',7,7'-Tetra[n,n-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD, 99.8% purity) was purchased from Boron Chemical Co., Ltd., China.

[0080] All chemical reagents used in this invention are used directly without further purification.

[0081] The test method of this invention: 1. X-ray diffraction and grazing incidence X-ray diffraction patterns were acquired using a high-resolution diffractometer (D8 Advance, Bruker) with a Cu Kα radiation source (λ = 1.5406 Å), a step size of 0.01°, and a scan rate of 10° min. - ¹.

[0082] 2. Scanning electron microscopy imaging was performed on a Helios 5CX (Thermo Fisher) at an operating voltage of 5 kV. X-ray photoelectron spectroscopy measurements were performed using an XR6 monochromatic Al Kα radiation source with a pass energy of 20 eV.

[0083] 3. The time-resolved photoluminescence (TRPL) signal was excited by a 375 nm picosecond laser (LDH-DC-375, PicoQuant), guided to a spectrometer (Ando Kymera 328i), and collected by a single-photon avalanche photodiode. The recorded TRPL spectrum was fitted using a double exponential delay function f(t) = A1exp(-t / τ1) + A2exp(-t / τ2), where A1 and A2 are the decay amplitudes, and τ1 and τ2 are the decay time constants.

[0084] 4. Transient absorption measurement: An infrared laser pulse was generated using an amplifier (Pharos, Light Conversion) with a pulse width of 170 fs, a wavelength of 1030 nm, and a repetition rate of 1 kHz. The pump pulse was directed to an optical parametric amplifier (Orpheus-F, Light Conversion) to generate a pulsed laser with a wavelength of 640 nm. Subsequently, a neutral density filter wheel and a neutral density filter were used to attenuate the pump light power, achieving a sample flux of 2.31 μJ / cm². - ². A probe laser carrying a 0.1 mJ pulse energy was attenuated and focused onto a yttrium aluminum garnet crystal to generate a supercontinuum probe spectrum. The probe laser was focused onto the sample, overlapping with the pump laser spot. The time delay was controlled by a translation stage, and the collected signals were analyzed using a USB spectrometer. UV-Vis spectra were obtained using a commercial UV-Vis spectrophotometer (Cary 300, Agilent, USA) or a custom-built spectrophotometer.

[0085] 5. The JV curves of the perovskite solar cells were obtained using source table (2162, Keithley) on an AM 1.5G spectrum generated by a AAA-grade solar simulator (Sirius-SS, Zolix) (one solar illumination; 100 mW cm⁻¹). - Measurements were performed under nitrogen-filled glove box conditions. All measurements were taken in reverse scan mode with a delay of 10 milliseconds. The effective area was 0.069 cm², defined by the shading mask. Light intensity was calibrated using an Oriel reference solar cell certified by the National Institute of Standards and Technology (NIST) to meet ISO-17025 standards.

[0086] 6. For the stability test of perovskite solar cells (light immersion), the unencapsulated perovskite solar cells are placed in a sealed quartz cell holder within a glove box filled with N2 and tested under sunlight of one intensity. For the maximum power point tracking test, the perovskite solar cell device is placed in a test chamber within a nitrogen glove box. A continuous flow of N2 is maintained to keep the test chamber temperature at 50°C. A maximum power point bias is applied to the device, and data points are collected periodically according to the ISOS-L-11 protocol.

[0087] 7. Low-dose scanning transmission electron microscopy characterization Cross-sectional samples of perovskite solar cell devices were fabricated using a dual-beam focused ion beam platform (Helios 5CX, Thermo Fisher). First, protective layers of 30 nm and 300 nm thickness were sequentially deposited on the top electrode (gold electrode) of the device using electron and ion beam deposition of platinum. Thin films were then fabricated using a gallium ion beam with an accelerating voltage of 30 kV and an operating current of 0.1–24 nA. To minimize ion beam damage, an amorphous layer was removed using an accelerating voltage of 1 kV and an operating current of 39 pA. Subsequently, the prepared sample thin films were transferred to a high-vacuum sputtering deposition system (Leica ACE 600) to disperse and deposit a carbon protective layer.

[0088] Low-dose scanning transmission electron microscopy (STEM) observations were performed at 300 kV on a spherical aberration-corrected electron microscope (Spectra 300, Thermo Fisher) equipped with a field emission gun. The convergence half-angle was 29.9 mrad, and the collection half-angle of the high-angle annular dark-field STEM detector ranged from 57 to 200 mrad. The electron probe beam current was reduced to 1 pA, and the residence time per pixel for atomic resolution images was 3 µs. For in-situ experiments, the residence time per pixel was reduced to 2 µs. The average acquisition size of the atomic resolution STEM images was approximately 34.5 × 34.5 nm², with 2048 × 2048 pixels. The size of each image acquired in the in-situ experiments was 100.8 × 100.8 nm², with 2048 × 2048 pixels. Based on this, the average dose rate for each atomic resolution image acquired was estimated to be approximately 53 e·Å. - ²·s - ¹. For each image acquired in situ, the average dose rate was further reduced to 6 e·Å. - ²·s - ¹. Electron energy loss spectral distribution was obtained using a Gatan image filter K3 camera in ADF-STEM mode, with a dispersion setting of 0.18 eV / channel, an incident aperture of 5 mm, and a beam current of 10 pA.

[0089] This invention uses FA 0.9 Cs 0.1 PbI3, FA 0.8 Cs 0.2 PbI3, FA 0.5 Cs 0.5 PbI3 and ((FA0.95Cs0.05)PbI3) 0.975 (MAPbBr3) 0.025 Perovskite thin films are used to study internal impurities (nanoclusters) in grains and the performance of perovskite solar cell devices.

[0090] FA 0.9 Cs 0.1Synthesis of PbI3 thin films: Step 1: Preparation of perovskite precursor solution: Dissolve 154.8 mg FAI, 26.0 mg CsI, 461.0 mg PbI2 and 20.3 mg MACl together in a DMF / DMSO mixed solvent (DMF / DMSO volume ratio of 7:3) to prepare FA 0.9 Cs 0.1 A perovskite precursor solution with a PbI3 precursor concentration of 1 mol / L. Step 2: Spin-coating preparation: Take 40 µL of perovskite precursor solution and deposit it onto an ITO conductive substrate covered with SnO2 (electron transport layer) using a three-step spin-coating method (first step: spin-coating at 500 rpm for 5 s; second step: spin-coating at 1000 rpm for 10 s; third step: spin-coating at 6000 rpm for 30 s). At the 10th s mark of the third spin-coating process, rapidly add 400 µL of EA. After spin-coating, anneal the perovskite film at 150°C for 20 min.

[0091] FA 0.8 Cs 0.2 Synthesis of PbI3 thin films: Step 1: Preparation of perovskite precursor solution: Dissolve 137.6 mg FAI, 52.0 mg CsI, 461.0 mg PbI2 and 20.3 mg MACl together in a DMF / DMSO mixed solvent (DMF / DMSO volume ratio of 7:3) to prepare FA 0.8 Cs 0.2 A solution with a PbI3 precursor concentration of 1 mol / L; Step 2: FA 0.8 Cs 0.2 The spin-coating process for PbI3 thin films is the same as that for FA. 0.9 Cs 0.1 PbI3 film.

[0092] FA 0.5 Cs 0.5 Synthesis of PbI3 thin films: Step 1: Preparation of perovskite precursor solution: Dissolve 86.0 mg FAI, 129.9 mg CsI, 461.0 mg PbI2 and 40.3 mg MACl together in 1 mL DMSO to prepare FA 0.5 Cs 0.5 A perovskite precursor solution with a PbI3 precursor concentration of 1 mol / L. Step 2: Spin-coating preparation: Take 40 µL of perovskite precursor solution and deposit it onto an ITO conductive substrate covered with SnO2 (electron transport layer) using a two-step spin-coating method (first spin-coating at 1000 rpm for 10 s, second spin-coating at 5000 rpm for 60 s). During the second spin-coating process, 380 µL of EA was rapidly added dropwise at 20 s and 40 s respectively. Then, the perovskite film was annealed in a glove box at 100 °C for 2 min, followed by annealing at 140 °C for 60 min at a relative humidity of 30-40%.

[0093] ((FA0.95Cs0.05)PbI3) 0.975 (MAPbBr3) 0.025 Synthesis of perovskite thin films: Step 1: Preparation of MAPbBr3 single crystals: Dissolve MABr and PbBr2 in DMF solvent at a molar ratio of 1:1 (the concentrations of MABr and PbBr2 are both 0.2 mol / L), and then add dichloromethane as an antisolvent to precipitate and capture MAPbBr3 single crystals. Step 2: Preparation of perovskite precursor solution: 228.8 mg FAI, 18.2 mg CsI, 705.3 mg PbI2, 33.67 mg MACl, and 18.2 mg MAPbBr3 single crystals were dissolved together in a mixed solvent of 890 µL DMF and 110 µL DMSO to prepare ((FA0.95Cs0.05)PbI3). 0.975 (MAPbBr3) 0.025 A perovskite precursor solution with a precursor concentration of 1.4 mol / L; Step 3: Spin-coating preparation: Take 50 µL of perovskite precursor solution and deposit it onto an ITO conductive substrate covered with SnO2 (electron transport layer) using a two-step spin-coating method (first spin-coating at 1000 rpm / min for 10 s, second spin-coating at 4000 rpm / min for 30 s). During the last 20 seconds of the second spin-coating process, add 1 mL of diethyl ether antisolvent to the center of the ITO conductive substrate within 1 second. Then, anneal the film at 100 °C for 40 min.

[0094] The method for synthesizing the ITO conductive substrate covered with SnO2 (electron transport layer) in the above perovskite thin film is as follows: SnO2 nanoparticles are diluted with distilled water at a volume ratio of 1:5. Then, the diluted solution is spin-coated on a pre-patterned ITO conductive substrate at a speed of 3000 rpm for 30 seconds, followed by annealing at 100°C for 10 minutes to form an ITO conductive substrate covered with SnO2.

[0095] The method for controlling the above perovskite thin films involves adding the additive NDPS to the perovskite precursor solution at appropriate concentrations. The concentrations of NDPS in the perovskite precursor solution are 0.5 mg / mL, 1 mg / mL, or 2 mg / mL.

[0096] Perovskite solar cell devices were constructed based on the above perovskite thin films (with or without additives) to study the influence of nanoclusters on the devices. The fabrication method of the devices is as follows: Step 1: Preparation of hole transport layer solution: Dissolve 72.3 mg Spiro-OMeTAD, 28.8 µL 4-tert-butylpyridine, and 17.5 µL lithium bis(trifluoromethanesulfonyl)imide in acetonitrile solution (concentration 520 mg / mL) in 1 mL chlorobenzene to obtain hole transport layer solution; Step 2: Take 50µL of hole transport layer solution and spin-coat it onto a perovskite film (with or without additives) at 3000rpm for 30s to form a hole transport layer. Step 3: Deposit an 80 nm thick gold electrode on the hole transport layer from Step 2 by thermal evaporation. The device structure is ITO conductive glass / electron transport layer / perovskite thin film / hole transport layer / electrode layer.

[0097] Furthermore, since the stability of the spiro-OMeTAD hole transport layer depends on its molecular stacking, it may degrade under long-term operating conditions, affecting the device's durability. Therefore, PTAA was used as the hole transport layer material in the stability testing of perovskite solar devices. The fabrication method of the device using PTAA as the hole transport layer material is as follows: 30 mg of PTAA and 3 mg of TPFB were dissolved in 1 mL of chlorobenzene to prepare the hole transport layer solution. 50 µL of the hole transport layer solution was spin-coated onto a perovskite film at 2000 rpm for 30 seconds. Finally, an 80 nm thick gold electrode was deposited by thermal evaporation.

[0098] Research and verification I. Revealing the Nanoclusters Inside Perovskite Grains 1. FA 0.5 Cs 0.5 PbI3 perovskite solar cells were used as research samples. Figure 1 For FA 0.5 Cs 0.5 Atomic structure of nanoclusters in PbI3 perovskite solar cells.

[0099] Figure 1 In the middle, 'a' represents the newly prepared FA. 0.5 Cs 0.5 PbI3 perovskite devices along

[010] oAtomic resolution HAADF-STEM images of the zone axis. (Source: [Insert Source Here]) Figure 1 It can be seen that all atomic sites in the perovskite grain are aligned with the orthorhombic perovskite phase (space group Pbnm) along

[010] . o The projections of the zone axis match. Figure 1 a indicates that a large number of irregularly shaped nanoclusters were observed inside the perovskite grains, such as Figure 1 As shown by the dashed line 'a', its average projected area is approximately 20 square nanometers. A magnified image of the nanoclusters is shown below. Figure 2 As shown. Figure 2 In the image, a~d are atomic resolution HAADF-STEM images of different regions of the perovskite grain.

[0100] Figure 1 Figure b is a schematic diagram of the experimental setup for STEM study of perovskite cross-sections. Figure 1 Figure b schematically illustrates the experimental setup for defocused imaging. Figure 1 b indicates that the electron beam is focused on the perovskite layer under over-focus and under-focus conditions, and on the nanoclusters buried inside the perovskite film under positive focus conditions.

[0101] Figure 1 Image c shows atomic resolution HAADF-STEM images of the defocus series acquired from the cross-sectional sample. From top to bottom, the images were acquired under overfocus, positive focus, and underfocus conditions, respectively. Figure 1 c indicates that the image under overfocus and underfocus conditions is related to the perovskite along

[010] . o The projection of the zone axis is highly consistent; and when the electron beam is in positive focus, the atomic lattice presented in the image corresponds to the non-perovskite impurity phase. This phenomenon confirms that the nanoclusters are completely buried inside the perovskite grains.

[0102] To further elucidate the precise atomic structure of this non-perovskite impurity phase (nanocluster), this invention obtained the nanoclusters along the three zone axes (

[010] ). o

[001] o and

[100] o Atomic resolution HAADF-STEM images. Figure 1 In the middle, d~f represent the distances along

[010] . o

[001] o and

[100] o Atomic-resolution HAADF-STEM images (high-angle annular dark-field images) of nanoclusters acquired along the zone axis, and their corresponding Fast Fourier Transform (FFT) plots. Figure 1As shown in d~f, the observed nanoclusters conform to a C-face-centered orthorhombic crystal system (space group Cmmm), with lattice parameters a = 0.926 nm, b = 1.309 nm, and c = 0.463 nm. The chemical formula of this single-cell nanocluster is A2BX4, where the A site is FA. + and Cs + The cation has a Pb² group at the B site. + X - isI - In FA x Cs 1-x In PbI3 thin films, the nanocluster phase can be expressed as (FA) x Cs 1-x )2PbI4.

[0103] Nanocluster phase atomic models such as Figure 3 As shown, Figure 3 In the diagram, a, b, and c represent three different directions. Figure 3 This indicates that the nanocluster phase is an A2BX4 phase, which exhibits one-dimensional crystallographic characteristics, and its structure consists of BX3 phases connected by common edges. - The nanoclusters are composed of octahedral chains, with A-site cations located between these one-dimensional chains. This invention uses image simulation to determine the FA in nanoclusters. + and Cs + The proportion, specifically as follows Figure 4 As shown. Figure 4 where a is (FA x Cs 1-x A series of image simulation results of nanocluster phases in 2PbI4 with different FA to Cs ratios. Figure 4 In Figure a, b represents the contour of the intensity line along the direction indicated by the arrow. Figure 4 The simulation results show that (FA) 0.4 Cs 0.6 The atomic images of 2PbI4 are in good agreement with the HAADF-STEM images of the nanoclusters obtained in the experiment.

[0104] (FA 0.4 Cs 0.6 The atomic positions within the unit cell of 2PbI4 are shown in Table 1.

[0105] Table 1. (FA) 0.4 Cs 0.6 Atomic positions in 2PbI4

[0106] Based on the atomic model structure of the nanocluster phase, the (FA) was drawn. 0.4 Cs 0.6A schematic diagram of the atomic structure of 2PbI4 projected along the three zone axes. Figure 1 In the diagram, g~i represent the drawn atomic structures of the nanoclusters along

[010] . o

[001] o and

[100] o Schematic diagram of projection along the zone axis ( Figure 1 The left image of g~i), corresponding to the simulated HAADF-STEM image ( Figure 1 (intermediate image of g~i) and electron diffraction pattern ( Figure 1 (The right side of g~i). Figure 1 g~i shows that it is related to Figure 1 The experimental results for d~f are highly consistent.

[0107] It is worth noting that the A2BX4 phase ((FA) 0.4 Cs 0.6 The Cs content in 2PbI4 is higher than that in perovskite grains (FA). 0.5 Cs 0.5 PbI3), indicating that cation segregation may induce the formation of nanoclusters. This invention further uses this atomic model to calculate the X-ray diffraction pattern of the A2BX4 phase, and the results are as follows: Figure 5 As shown. Figure 5 Simulated XRD patterns of γ-CsPbI3, Cs2PbI4, PbI2, δ-CsPbI3, and δ-FAPbI3 are shown. Figure 5 It can be seen that A2BX4 phase (corresponding to Figure 5 In the case of Cs₂PbI₄ (since component A in the A₂BX₄ phase has no significant impact on the XRD simulation results, simulation verification of Cs₂PbI₄ is sufficient), the main diffraction peaks overlap with those of PbI₂, indicating that X-ray diffraction cannot reliably distinguish between A₂BX₄ and PbI₂. In particular, this nanoscale A₂BX₄ phase is encapsulated within a crystalline perovskite matrix, making it almost undetectable in perovskite films typically containing PbI₂ impurities.

[0108] 2. With FA 0.8 Cs 0.2 PbI3 and FA 0.9 Cs 0.1 PbI3 perovskite solar cells were used as research samples. Figure 6 and Figure 7 FA 0.8 Cs 0.2 PbI3 perovskite samples and FA 0.9 Cs 0.1 Atomic resolution HAADF-STEM image of PbI3 perovskite sample. Figure 6 and Figure 7Images a and b in the image are atomic resolution HAADF-STEM images of different regions within a perovskite grain. Figure 6 and Figure 7 It is known that these A2BX4 type nanoclusters are also commonly found in FA. 0.8 Cs 0.2 PbI3 and FA 0.9 Cs 0.1 In PbI3 perovskites, it can be inferred that cation segregation within the perovskite lattice may lead to the following reaction: 2(FA,Cs)PbI3 → (FA,Cs)2PbI4 + PbI2. Therefore, these A2BX4 type nanoclusters coexist with intracrystalline lead iodide nanoclusters. Thus, suppressing cation segregation is expected to prevent the formation of nanoclusters.

[0109] II. The Influence of Nanoclusters on the Performance of Perovskite Devices Take FA 0.5 Cs 0.5 PbI3 perovskite solar cells were used as samples for research. Figure 8 To understand the thermodynamic stability and electronic structure of nanoclusters in perovskite.

[0110] Figure 8 Figures a-b show in-situ atomic-scale observations of the degradation process involving nanoclusters in perovskite. Figure 8 'a' is the unexposed FA. 0.5 Cs 0.5 PbI3 perovskite original sample Figure 8 In the middle b, FA was observed after 45 minutes of exposure in an air environment with 50% relative humidity and 25°C using STEM. 0.5 Cs 0.5 An observation image of a PbI3 perovskite sample (i.e., a quasi-in-situ observation). Figure 8 The insets in figures a and b are the corresponding FFT plots. Figure 8 From a and b, we know that after exposure, in the original (FA) 0.4 Cs 0.6 The location of the 2PbI4 impurity evolved into the lead iodide (PbI2) phase. The corresponding fast Fourier transform spectrum (…) Figure 8 The illustrations (a) and (b) confirm the presence of PbI2. Conversely, no significant structural changes were observed in the grain boundary regions where nanoclusters were absent.

[0111] Figure 9 To make FA 0.5 Cs 0.5 HAADF-STEM image of PbI3 perovskite after one week of storage in vacuum packaging. Figure 9 a and b are FA 0.5 Cs 0.5HAADF-STEM images of different regions of PbI3 perovskite. Figure 9 c, d, and e are respectively Figure 9 a and Figure 9 A magnified image of the local area shown in box b. Figure 9 Nanoclusters (FA) can be observed 0.4 Cs 0.6 The phenomenon of coexistence of 2PbI4 and high-density PbI2 grains. The average particle size of PbI2 exceeds that of the original (FA) 0.4 Cs 0.6 )2PbI4 impurity (with Figure 1 (a corresponds to). In-situ and quasi-in-situ observations together indicate that a one-dimensional (FA) formed during the preparation process... 0.4 Cs 0.6 The 2PbI4 structure is metastable and readily decomposes into PbI2 under environmental stress. Meanwhile, the (FA) structure... 0.4 Cs 0.6 The PbI2 derived from 2PbI4 will further induce the degradation of the surrounding perovskite phase.

[0112] Density functional theory (DFT) calculations were used to investigate the effects of A2BX4 nanoclusters on the structural stability and optoelectronic properties of perovskite grains. DFT calculations were performed using the Vienna first-principles simulation package (VASP), employing the projected fused wave method to describe electron-ion interactions. The generalized gradient approximation (GGA) exchange-correlated functional (Perdew-Burke-Ernzerhof, PBE) was used, with a kinetic energy cutoff of 450 eV and a Gaussian broadening of 0.05 eV. Lattice parameters and atomic positions were fully relaxed until the interatomic forces converged to a threshold of 0.02 eV / Å. For the calculation of formation energy and density of states, 5×5×4 and 4×3×8 k-point grids centered at Γ were used for CsPbI3 and Cs2PbI4, respectively. The band-aligned calculations for CsPbI3 and Cs2PbI4 employed a plate model with a 15 Å vacuum layer above the plate. The formation energy (ΔEf) was calculated using the following formula: ΔE f (CsPbI3) = E fu (CsPbI3) – E fu (CsI) – E fu (PbI2); ΔE f (Cs2PbI4) = E fu (Cs2PbI4) – 2E fu (CsI) – E fu (PbI2); Where E fuThis represents the total energy per molecular unit of the substance in parentheses.

[0113] Figure 10 Phase diagram of Cs-Pb-I ternary system calculated for DFT ( Figure 10 A schematic diagram of energy changes during the decomposition of the perovskite phase and the nanocluster phase (a) Figure 10 (b) Cs2PbI4 is a metastable phase with a formation energy higher than that of the convex hull, and therefore is not shown in the phase diagram. Figure 10 This indicates that Cs₂PbI₄ is a metastable phase located on the junction line between CsPbI₃ and Cs₄PbI₆. Structural optimization of the nanocluster phase was performed using an experimentally determined orthorhombic structure as the initial configuration, which exhibits a quasi-face-centered cubic (FCC) sublattice composed of iodine ions. This characteristic matches that of the perovskite phase. In the perovskite phase, anionic iodine reacts with FA... + / Cs + Cations also form quasi-face-centered cubic sublattices.

[0114] Using stable binary compounds CsI and PbI2 as references, the formation energies of CsPbI3 and Cs2PbI4 were calculated. Figure 8 c represents the formation energy of the perovskite mineral phase (i.e., CsPbI3) and the nanocluster phase (i.e., Cs2PbI4) with cesium iodide (CsI) and lead iodide (PbI2) as references. Figure 8 c indicates that the unit formation energies per chemical formula of CsPbI3 and Cs2PbI4 are -0.048 eV and -0.016 eV, respectively. The smaller negative formation energy of Cs2PbI4 indicates its lower thermodynamic stability and a greater tendency to decompose into CsI and PbI2 (e.g., CsPbI3 and Cs2PbI4). Figure 10 b).

[0115] Figure 8 d represents the density of states and band arrangement of the perovskite mineral phase (CsPbI3) and the nanocluster phase (Cs2PbI4). Figure 8 The data shows that perovskite exhibits a larger band gap (2.84 eV) than nanoclusters (1.83 eV), which means that nanoclusters have very weak absorption of visible light, thus affecting photoelectric properties.

[0116] Furthermore, the formation of nanoclusters introduces numerous additional intracrystalline interfaces. This invention resolves three types of perovskite-nanocluster interfaces at the atomic scale, and based on this, constructs atomic models to calculate the corresponding electronic structures, with results as follows: Figure 8 As shown in e~s. Figure 8 e~s represents the atomic resolution HAADF-STEM image of the original interface between the perovskite and the nanoclusters, as well as the iodine vacancy situation in the interface region and the corresponding projected density of states (PDOS).

[0117] Figure 8 In the middle, e~i represent the perovskite-nanocluster interface I ( Figure 8 e) The projected density of states corresponding to the vacant interface ( Figure 8 f) The partial charge density of defect states near the bottom of the conduction band at the vacancy-free interface (0.0005 e / Bohr³). Figure 8 g) The spin-polarized projected density of states corresponding to the configuration containing one iodine vacancy at the interface ( Figure 8 h) In a configuration containing one iodine vacancy at the interface, the partial charge density corresponding to the defect state generated by the iodine vacancy (0.0005 e / Bohr³, Figure 8 i). Figure 8 j~n represent the perovskite-nanocluster interface II ( Figure 8 j), the projected density of states corresponding to the vacant interface ( Figure 8 k), the partial charge density of defect states near the bottom of the conduction band at the vacancy-free interface (0.0005 e / Bohr³), Figure 8 l), the spin-polarized projected density of states corresponding to the configuration containing one iodine vacancy at the interface ( Figure 8 In a configuration containing one iodine vacancy at the interface (m), the partial charge density corresponding to the defect state generated by the iodine vacancy (0.0005 e / Bohr³) is... Figure 8 n).

[0118] Figure 8 o~s represent the perovskite-nanocluster interface III ( Figure 8 o), the projected density of states corresponding to the vacant interface ( Figure 8 p), the partial charge density of defect states near the bottom of the conduction band at the vacancy-free interface (0.0005 e / Bohr³), Figure 8 q) The spin-polarized projected density of states corresponding to the configuration containing an iodine vacancy at the interface ( Figure 8 r), In a configuration containing one iodine vacancy at the interface, the partial charge density corresponding to the defect state generated by the iodine vacancy (0.0005 e / Bohr³, Figure 8 s).

[0119] Figure 8 Color designation in c, 8g, 8l, 8q, 8i, 8n, 8s: A + , cyan; Pb² + gray; I - ,Purple. Figure 8 The dashed lines in f, 8k, 8p, 8h, 8m, and 8r correspond to the Fermi levels. Figure 8 The color illustrations in e, 8j, and 8o are atomic models of the perovskite-nanocluster interface.

[0120] Because the two phases share a specific sublattice structure type (quasi-face-centered cubic), their structural similarity leads to a low mismatch degree between specific crystal planes of CsPbI3 and Cs2PbI4, thus forming a semi-coherent interface revealed by STEM. For example... Figure 8 f、 Figure 8 As shown in g, the interface (interface I) formed by the (101) crystal plane of CsPbI3 and the (110) crystal plane of Cs2PbI4 generates multiple defect states near the conduction band bottom (CBM) of CsPbI3. These defect states are mainly localized on specific PbI6 polyhedra at the interface and are primarily contributed by the p orbitals of Pb atoms. The localized trap states exhibited by the pristine perovskite-nanocluster interface indicate that nanoclusters have an inherently detrimental effect on the photoelectric conversion efficiency of devices. Even without other defects, nanoclusters can significantly increase the recombination of photogenerated carriers.

[0121] Figures 11-13 They are respectively Figure 8 Partial charge density (0.0005 e / Bohr³) of occupied states (yellow area) near VBM at interface I shown in Figure e. Figure 8 Partial charge density (0.0005e / Bohr³) of occupied states (yellow area) near VBM of interface II shown in j. Figure 8 Partial charge density (0.0005 e / Bohr³) of occupied states (yellow region) near VBM of interface III shown in o. Figures 11-13 This indicates that the valence band peak (VBM) at the interface is contributed by the perovskite region, exhibiting delocalization characteristics similar to bulk materials. These interfaces can serve as aggregation points for migration point defects. Therefore, this study also investigated the impact of point defects on the optoelectronic performance of devices containing nanoclusters. Figure 8 h and 8i demonstrate the relevant results for interface I. Given the iodine vacancy (V I The formation energy of V is relatively low, and it can be expected that during the operation of perovskite devices, V I It accumulates over time and interacts with the perovskite-nanocluster interface. Calculation results show that V I This generates localized trapped states at the interface, thereby increasing carrier recombination. Similar to the analysis of vacancies at interface I, other interface configurations (interfaces II and III) also show corresponding analytical results, such as... Figure 8 As shown in j and 8o. Furthermore, regardless of the presence of point defects, defect states can occur in each configuration. These defect states are located near the conduction band bottom (CBM) and are primarily localized on Pb atoms at the interface. Figure 8 k~n and Figure 8 These, acting as localized trap states, significantly enhance electron-hole recombination. On the other hand, no empty states appear near the valence band top (VBM), and the highest occupied states exhibit a delocalized distribution (p~s). Figures 11-13This indicates that the interface structure only contributes defect states near the bottom of the conduction band.

[0122] III. Regulation of Nanoclusters This invention regulates the nanoclusters inside perovskites by introducing different concentrations of NDPS into different perovskite precursor solutions.

[0123] 1. Geometric Phase Analysis (GPA) of FA-Cs Perovskite The existing literature, "Microstructure within Grain Boundaries of Perovskite Semiconductors" (Cai, S. et al. Atomically resolved electrically active intragrain interfaces in perovskites semiconductors. J. Am. Chem. Soc. 144, 1910-1920 (2022)), revealed the ubiquitous nanoscale Cs cation segregation in FA-Cs perovskites and the resulting inhomogeneous strain distribution within the grains through geometrical phase analysis (GPA). Building upon this, since nanoclusters may form simultaneously with cation segregation, this invention utilizes GPA to identify the lattice mismatch between perovskite and nanoclusters, as well as the residual strain in perovskite grains caused by cation segregation. Figure 14 The figure shows the results related to the regulation of nanoclusters.

[0124] Figure 14 a is FA 0.5 Cs 0.5 The PbI3 sample contains ( Figure 14 (left side image) and does not contain ( Figure 14 (a) GPA analysis of the nanocluster region (right side). The orange dashed line indicates the location of the nanoclusters. Figure 14 The study shows that in perovskite grains containing high-density nanoclusters, significant strain concentration occurs not only around the nanoclusters but also in adjacent perovskite regions. However, in regions without nanoclusters, the strain concentration becomes weak, suggesting that Cs cation segregation plays a crucial role in promoting the formation of such impurity nanoclusters.

[0125] 2. The regulatory effect of NDPS on nanoclusters Figure 15 The diagram shows the structure of the NDPS and the calculated electrostatic potential distribution. Figure 15 In the diagram, a represents the structure of the NDPS, and b represents the calculated electrostatic potential distribution. Figure 15 This reveals that NDPS contains electron-deficient quaternary ammonium groups and negatively charged sulfonic acid groups, which can serve as coordinating cations (such as Pb²⁺). + ) and anions (such as I) -NDPS provides favorable sites. The following study investigates and analyzes the regulatory effect of NDPS on nanoclusters.

[0126] Figure 16 For containing 0 mg / mL NDPS ( Figure 16 a, initial state), 0.5 mg / mL NDPS ( Figure 16 b) 1 mg / mL ( Figure 16 c) and 2 mg / mL NDPS ( Figure 16 d) FA 0.9 Cs 0.1 Scanning electron microscope image of PbI3 thin film. Figure 17 For containing 0 ( Figure 17 FA (in its initial state), containing 0.5 mg / mL, 1 mg / mL and 2 mg / mL NDPS 0.9 Cs 0.1 Grain size distribution of PbI3 thin films. Figure 16 and Figure 17 This indicates that, compared to the original sample, incorporating NDPS into FA... 0.9 Cs 0.1 The PbI3 precursor solution did not significantly affect the perovskite grain size.

[0127] Figure 18 For containing 0 ( Figure 18 FA at initial state), 0.5 mg / mL, 1 mg / mL and 2 mg / mL NDPS 0.9 Cs 0.1 XRD pattern of PbI3 thin film. Figure 18 Analysis showed that the large-sized NDPS molecules were not incorporated into the perovskite lattice, nor did they form large-scale impurity phases in the film. Furthermore, Figure 18 It was also shown that the diffraction peaks of the impurity phase gradually weakened with increasing NDPS concentration, indicating that Pb² + I - There is a strong coordination interaction with NDPS molecules.

[0128] Figure 19 To start from 0 ( Figure 19 FA at initial state), 0.5 mg / mL, 1 mg / mL and 2 mg / mL NDPS 0.9 Cs 0.1 S 2p (PbI3 thin film obtained) Figure 19 a) and N 1s ( Figure 19 b) X-ray photoelectron spectroscopy. Figure 19 The dashed lines represent the newly emerging S 2p and N 1s peaks. For example... Figure 19As shown, a new peak appears at approximately 402.5 eV in the N 1s spectrum of the perovskite film containing NDPS, which clearly indicates that NDPS has been successfully incorporated into the perovskite film.

[0129] Figure 14 b represents FA containing 0 mg / mL, 0.5 mg / mL, and 1 mg / mL NDPS. 0.9 Cs 0.1 XPS spectra of Pb4f and I3d obtained from PbI3 thin films. Figure 14 The dashed line in b represents the peak positions of Pb 4f and I 3d in the original sample. Figure 14 b indicates that, compared to the original sample, the Pb 4f and I 3d peaks of the perovskite films containing 0.5 mg / mL and 1 mg / mL NDPS shift to lower binding energies, indicating that Pb² + I - There is a coordination relationship between it and NDPS.

[0130] To evaluate the FA with / without adding NDPS 0.9 Cs 0.1 The residual strain in the PbI3 thin film was analyzed by grazing incidence X-ray diffraction (GIXRD) using the 2θ-sin²(ψ) method. Based on FA... 0.9 Cs 0.1 Due to the cubic symmetry of PbI3, strain analysis was performed using the (012) reflection located near 31.5°, which exhibits multiplicity and a stronger diffraction signal, providing the most reliable information on structural symmetry. Detailed X-ray diffractometer settings are shown in Table 2.

[0131] Table 2. X-ray diffractometer settings for grazing incidence X-ray diffraction measurements

[0132] Figure 14 c represents 0 mg / mL NDPS ( Figure 14 (c) and FA at 1 mg / mL NDPS 0.9 Cs 0.1 GIXRD patterns of the (012) crystal plane of PbI3 thin film at different tilt angles. The dashed line shows the change of the (012) peak position with the tilt angle. Figure 20 For containing 0.5 mg / mL ( Figure 20 a) and 2 mg / mL NDPS ( Figure 20 b) FA 0.9 Cs 0.1 GIXRD patterns of the (012) crystal plane of PbI3 thin film at different tilt angles. The dashed line shows the change of the (012) peak position with the tilt angle.

[0133] Figure 14 c and Figure 20 This indicates that as ψ increases from 0° to 50°, FA containing 0 mg / mL NDPS... 0.9 Cs 0.1 PbI3 film and FA containing 0.5 mg / mL NDPS 0.9 Cs 0.1 The (012) diffraction peaks of the PbI3 film gradually shifted to lower angles (as shown by the dashed lines), confirming the presence of residual tensile strain. However, compared with FA containing 0 mg / mL NDPS... 0.9 Cs 0.1 Compared to PbI3 films, FA containing 0.5 mg / mL NDPS... 0.9 Cs 0.1 The small angular shift in the PbI3 film indicates that the strain was partially relieved. When the NDPS concentration reached above 1 mg / mL, the peak shift completely disappeared, indicating that the residual tensile strain had been completely released. Figure 14 c and Figure 20 b).

[0134] To further confirm the inhibitory effect of NDPS on nanoclusters, this invention investigated the inhibitory effect of FA based on 1 mg / mL NDPS. 0.5 Cs 0.5 PbI3 perovskite solar cells and FA containing 1 mg / mL NDPS 0.9 Cs 0.1 Atomic-resolution HAADF-STEM imaging and GPA analysis were performed on PbI3 perovskite solar cells, and the results are as follows: Figure 21 As shown. Figure 21 FA containing 1 mg / mL NDPS 0.5 Cs 0.5 PbI3 perovskite solar cells and FA containing 1 mg / mL NDPS 0.9 Cs 0.1 Atomic resolution HAADF-STEM image and geometric phase analysis diagram of PbI3 perovskite solar cells. Figure 21 In this context, 'a' and 'b' represent FA containing 1 mg / mL NDPS. 0.5 Cs 0.5 HAADF-STEM images of PbI3 perovskite solar cells in different regions, c and d represent FA containing 1 mg / mL NDPS. 0.9 Cs 0.1 HAADF-STEM images of PbI3 perovskite solar cells in different regions, e~h correspond to the geometric phase analysis of images a~d, respectively. Figure 21 It can be seen that no nanoclusters were observed in the perovskite grains, which is consistent with the release of strain concentration due to cation homogenization.

[0135] To further reveal the distribution of NDPS in perovskite thin films, this invention performed electron energy loss spectroscopy (EELS) measurements using sulfur as a tracer element in annular dark field (ADF)-STEM mode. Figure 14 In the image, d represents an ADF-STEM image of a FA0.9Cs0.1PbI3 perovskite solar cell containing 2 mg / mL NDPS. Figure 14 (d above figure) and the corresponding S-element EELS surface distribution results ( Figure 14 (See diagram below, SL). Figure 14 The results show that no impurity phases were observed in the low-magnification ADF-STEM images obtained from FA0.9Cs0.1PbI3 perovskite solar cells with 2 mg / mL NDPS. The elemental surface distribution of S indicates that NDPS is enriched only at grain boundaries (GBs), consistent with the XRD results. This suggests that Pb²⁺... + I - The strong coordination of NDPS around grain boundaries can passivate the grain boundaries, thereby improving the stability of perovskite films. Furthermore, as confirmed by in-situ characterization in this invention, the interior of grains containing nanoclusters begins to degrade before reaching the grain boundaries, indicating that eliminating nanoclusters is more critical than passivating grain boundaries.

[0136] Figure 14 The diagram illustrates the mechanism of NDPS-induced chemical elimination of nanoclusters. The amphiphilic nature of NDPS—possessing both negatively and positively charged active groups—enables it to coordinate with solute species, including cationic clusters in the precursor solution. These interactions enhance the miscibility and dispersibility between components, reduce the size of cationic clusters, and increase the density of nucleation sites. During crystallization, NDPS coordinates with these cationic clusters and slows down the crystallization process, achieving a higher level of intracrystalline homogeneity and providing sufficient time for thorough mixing of cations, thereby preventing the formation of cationic segregated phases such as A2BX4.

[0137] IV. The Influence of Nanoclusters on the Photovoltaic Performance of Perovskite Solar Cell Devices This invention further investigates the influence of nanoclusters on the performance and stability of perovskite solar cells (PSCs). Figure 22 These are the results of relevant research.

[0138] Figure 22 In the middle, 'a' represents FA containing 0 and 1 mg / mL NDPS. 0.9 Cs 0.1 Time-resolved photoluminescence spectra of PbI3 thin films (structure: glass / ITO / electron transport layer / perovskite thin film layer). Fitting parameters are shown in Table 3.

[0139] Table 3. Fitting parameters for time-resolved photoluminescence spectra

[0140] Figure 22 a and the comparison in Table 3 indicate FA without NDPS. 0.9 Cs 0.1 PbI3 thin films, experiments showed that FA with 1 mg / mL NDPS was added. 0.9 Cs 0.1 PbI3 thin film. (The text appears to be incomplete and contains several grammatical errors. A more accurate translation would require the full context.) Figure 22 As shown in a and Table 3, compared with FA without NDPS... 0.9 Cs 0.1 Compared to PbI3 films, FA with 1 mg / mL NDPS... 0.9 Cs 0.1 The average photoluminescence lifetime of the PbI3 film decreased from 61.81 nanoseconds to 9.79 nanoseconds, indicating that nonradiative recombination was suppressed by eliminating impurity nanoclusters inside the perovskite grains.

[0141] Figure 22 b represents the FA without NDPS. 0.9 Cs 0.1 Transient absorption spectrum of PbI3 thin film (control); Figure 22 c represents FA with 1 mg / mL NDPS added. 0.9 Cs 0.1 Transient absorption spectrum of PbI3 thin film (experimental). Figure 22 b and c indicate that all samples underwent bandgap renormalization and hot carrier cooling within 2 ps after photoexcitation. Figure 22 Faster decay kinetics were observed in c, with a narrower full width at half maximum (FWHM) at 0.84 ps. The FWHMs of the control and experimental films were 35.3 nm and 32.8 nm, respectively, indicating that the experimental film had less energy level broadening. This is attributed to the presence of fewer nanoclusters in the film after the addition of NDPS.

[0142] This invention further tests the stability of films with and without NDPS under environmental conditions (22°C, 40% relative humidity). The results are as follows... Figure 23 and Figure 24 As shown. Figure 23 FA without NDPS 0.9 Cs 0.1 PbI3 thin film (control), Figure 23 a) and FA with 1 mg / mL NDPS added 0.9 Cs 0.1 PbI3 thin film (experimental) Figure 23b) UV-Vis absorption spectra as a function of storage time under laboratory conditions Figure 24 FA without NDPS 0.9 Cs 0.1 PbI3 film (control) and FA with 1 mg / mL NDPS added 0.9 Cs 0.1 The graph shows the change in absorbance (at 760 nm) of PbI3 thin film (experimental) over storage time. Figure 24 This indicates that the absorbance of the experimental group film remained almost unchanged after 40 days of storage, demonstrating better stability than the control group.

[0143] Figure 22 d represents the control group (without NDPS added) (FA 0.95 Cs 0.05 PbI3) 0.975 (MAPbBr3) 0.025 (Perovskite solar cells) and experimental group (containing 2 mg / mL NDPS of ((FA0.95Cs0.05)PbI3)) 0.975 (MAPbBr3) 0.025 (Perovskite solar cells) JV curve of perovskite solar cells.

[0144] Table 4. Photoelectric parameters of perovskite solar cells in the control and experimental groups

[0145] Figure 22 Tables d and 4 show that the photoelectric conversion efficiency of the experimental group (experimental group) without nanoclusters was improved to 26.03%, and the short-circuit current density was 26.29 mA cm⁻¹. -2 The open-circuit voltage is 1.206 V, and the fill factor is 0.821. In contrast, the control group device has a PCE of only 23.85% and a short-circuit current density of 26.06 mA cm⁻¹. -2 The open-circuit voltage is 1.166 V, and the fill factor is 0.785. A significant contribution of this invention to improving PCE is the increase in open-circuit voltage.

[0146] Figure 22 The graph in Figure e shows the power conversion efficiency (PCE) output of the two perovskite solar cells in the control and experimental groups at the maximum power point (MPP). Figure 22 e indicates that, compared to the control group, the battery device with added NDPS to eliminate nanoclusters has a faster photoelectric response from the dark state to the light state.

[0147] Figure 25The chart shows the power conversion efficiency statistics for two types of perovskite solar cells in the control and experimental groups (n=30 devices per group). Each box plot shows the mean, median, upper edge, lower edge, and the box boundaries at 25% and 75%. Figure 25 This indicates that the fabricated nanocluster-free battery devices (experimental group) exhibit better reproducibility than the control group devices.

[0148] This invention presents perovskite solar cell device samples fabricated using PTAA as the hole transport layer material, and compares the device stability and durability. The test results are as follows: Figure 22 As shown in f.

[0149] Figure 22 The figure in f represents the MPP tracking stability test of the control and experimental groups of perovskite solar cells based on the ISOS-L-11 protocol. Figure 22 f shows that after 1000 hours of continuous testing under single-solar-intensity illumination (ISOS-L-11 protocol), the experimental group devices still maintained an impressive 95.21% of the initial PCE, while the PCE of the control group devices rapidly decayed in the first 100 hours.

[0150] This invention further investigates the storage stability of two perovskite devices. After storing the two perovskite devices in a glove box for two weeks, STEM characterization tests were performed, and the results are as follows: Figure 26 As shown.

[0151] Figure 26 In the figure, a and b are low-magnification HAADF-STEM images of the cross-sectional samples of the control group and the experimental group, respectively; c and d are atomic resolution HAADF-STEM images of the cross-sectional samples of the control group and the experimental group, respectively; e and f are geometric phase analyses of the images shown in c and d, respectively. Figure 26 The results showed that PbI2 was observed in the grain interior and grain boundaries of the control group (perovskite containing nanoclusters) after two weeks of storage in a glove box. In contrast, no degradation products were observed in the experimental group samples. Furthermore, atomic resolution imaging revealed that the experimental group perovskite, without residual strain, maintained the integrity of its crystal structure. In contrast, the perovskite in the control group samples partially degraded into PbI2 nanoparticles, confirming that perovskite devices with cleared nanoclusters exhibited better stability and durability.

[0152] In summary, this invention reveals the presence of metastable A2BX4 phase nanoclusters at the atomic scale within the nominally prepared FA-Cs perovskite thin film grains. These nanophases exhibit a much larger band gap than perovskite, hindering carrier transport within the grains and accelerating nonradiative recombination. More importantly, under environmental conditions, they readily decompose into PbI2, becoming an intrinsic factor affecting the chemical stability of the perovskite grains. This invention eliminates these nanoclusters through a chemical method (introducing NDPS), significantly improving the photoelectric conversion efficiency and stability of perovskite solar cells. The perovskite solar cell prepared after eliminating nanoclusters in this invention achieves a photoelectric conversion efficiency of 26.03%, and the T95 operating stability of the device exceeds 1000 hours.

Claims

1. An additive for regulating nanoclusters within perovskite grains, characterized in that, The additives include electron-deficient quaternary ammonium groups and negatively charged sulfonic acid groups.

2. The additive according to claim 1, characterized in that, The additive is alkyl dimethyl propanesulfonate.

3. The additive according to claim 1, characterized in that, The additive includes at least one of 3-(N,N-dimethyldecylammonium)propanesulfonate, 3-(N,N-dimethyldodecylammonium)propanesulfonate, 3-(N,N-dimethylmyristylammonium)propanesulfonate, 3-(N,N-dimethylhexadecylammonium)propanesulfonate, and 3-(N,N-dimethylstearylammonium)propanesulfonate.

4. A perovskite precursor solution, characterized in that, The perovskite precursor solution includes the additives described in any one of claims 1 to 3.

5. The perovskite precursor solution according to claim 4, characterized in that, In the perovskite precursor solution, the molar ratio of the additive to the perovskite precursor is (0.001~0.02):

1.

6. The perovskite precursor solution according to claim 4, characterized in that, The concentration of the additive is 0.5~2 mg / mL; And / or, the concentration of the perovskite precursor is 0.5~1.8 mol / L.

7. A method for regulating nanoclusters within perovskite grains, characterized in that, The method includes adding the additive according to any one of claims 1 to 3 to the perovskite precursor solution.

8. The method according to claim 7, characterized in that, The nanoclusters include an A2BX4 structure, and the perovskite precursor includes an ABX3 structure; wherein the A site is an organic cation and / or a cesium ion, the B site is a coordinating cation, and the X site is a halide anion.

9. The method according to claim 8, characterized in that, The organic cations include formamidinium ions or methylamine ions; And / or, the coordinating cation includes at least one of lead ion, tin ion, and germanium ion; And / or, the halide anion includes at least one of bromide ions, iodide ions, and chloride ions.

10. The method according to claim 7, characterized in that, The nanoclusters are (FA) x Cs 1-x )2PbI4, 0 < x < 1; And / or, the perovskite precursor includes FA 0.9 Cs 0.1 PbI3, FA 0.8 Cs 0.2 PbI3, FA 0.5 Cs 0.5 PbI3, ((FA0.95Cs0.05)PbI3) 0.975 (MAPbBr3) 0.025 At least one of them.

11. The method according to claim 7, characterized in that, The area of ​​the nanoclusters is less than 20 square nanometers.

12. A perovskite thin film, characterized in that, The perovskite film is formed from the perovskite precursor solution according to any one of claims 4 to 6.

13. A perovskite battery, characterized in that, The perovskite solar cell includes the perovskite thin film of claim 12.

14. A photovoltaic module, characterized in that, The photovoltaic module includes the perovskite thin film of claim 12 or the perovskite cell of claim 13.

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