Perovskite solar cell based on chalcogen ligand material and preparation method thereof

Abstract

The application discloses a perovskite solar cell based on chalcogen ligand material and a preparation method thereof, and the generation and accumulation of perovskite deep level defects are induced by the periodic change of lattice stress in the day-night cycle operation mode, which aggravates the ion migration behavior of the perovskite, thereby accelerating the performance decay of the device. T 80 The application develops a series of chalcogen ligand materials to eliminate the change of lattice stress and stabilize the perovskite lattice. Through a double strategy of crystallization optimization and lattice anchoring, a higher-symmetry room-temperature stable pseudo-cubic phase FAPbI3 is obtained, the light and heat-induced lattice expansion and contraction are inhibited, and the change of lattice stress is eliminated. The perovskite solar cell prepared based on the strategy has excellent photoelectric conversion efficiency (PCE) and stability, and the PCE is increased by 10 times in the day-night cycle operation mode T 80 The device stability based on various international summit agreements (ISOS) for organic photovoltaic stability tests is also greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photovoltaic materials, and particularly relates to application of multifunctional chalcogenide ligand material in perovskite solar cells, so that a perovskite solar cell with high efficiency and high stability can be obtained. BACKGROUND

[0002] In the past decade, the stability of perovskite solar cells in specific environments (such as high humidity (55-85% ambient humidity), high temperature (65-85℃), maximum power point tracking and continuous light, etc.) has never stopped being studied. Most of these studies are based on stability test protocols (such as the International Summit on Organic Photovoltaic Stability (ISOS)) to evaluate the lifetime of perovskite solar cells, and usually only involve a specific environmental variable. However, in practical applications, perovskite solar cells work in a day-night cycle mode, which often involves multiple external environmental changes, such as periodic light, temperature fluctuations, etc., making the degradation process of perovskite more complex. So far, the stability of perovskite solar cells in the day-night cycle mode has been rarely studied.

[0003] Currently, the most commonly used stability protocol (ISOS) for evaluating the lifetime of perovskite solar cells is based on the standard of silicon solar cells. However, unlike single-crystal silicon, polycrystalline perovskite thin films have ion defects, and perovskite solar cells tend to exhibit defect-induced “fatigue” behavior in the day-night cycle mode. Specifically, the device efficiency decreases under light, and shallow level defects can perform “self-repair” of the lattice in the dark environment, restoring part of the efficiency. This “self-repair” behavior is not possessed by silicon solar cells. Therefore, the rigor of evaluating the lifetime of perovskite solar cells according to the ISOS protocol is questionable. Studies have shown that in the continuous light mode, the perovskite lattice expands, and the lattice stress gradually releases; while in the day-night cycle mode, the changes in light and temperature induce the expansion and contraction of “soft lattice” perovskite, generating periodic lattice stress. Previous studies on the day-night cycle stability of perovskite solar cells mostly stabilized the temperature at room temperature, ignoring the influence of temperature. Therefore, it is crucial to further study the influence of the superposition of light and heat in the day-night cycle mode on the lifetime of the device.

[0004] To improve the service life of perovskite solar cells, researchers are keen to use functional molecular ligands to regulate the crystal orientation, phase composition and thermal expansion behavior of perovskite to stabilize the perovskite lattice. For example, during the preparation of perovskite solar cells, by adding organic ammonium salt, functional polymer, crosslinking agent and other functional materials to the perovskite precursor solution to prepare perovskite thin film, the crystal regulation mechanism or lattice anchoring effect of functional materials is used to improve the stability of perovskite solar cells. However, most of these strategies are aimed at solving the stability problem of perovskite solar cells under specific aging conditions, and there are few studies on improving the service life of perovskite solar cells under day-night cycle working mode.

[0005] Therefore, it is urgent to explore an effective lattice stress regulation method that can realize the preparation of room temperature stable FAPbI3 without affecting the perovskite components, effectively inhibit the lattice expansion and contraction induced by light and heat, reduce the influence of perovskite lattice strain on the stability of the device under day-night cycle working mode, and then prepare perovskite solar cells with high efficiency and excellent stability. SUMMARY

[0006] The purpose of the present application is to provide a perovskite solar cell and a preparation method thereof, which uses a perovskite precursor solution doped with a chalcogen ligand material to prepare room temperature stable FAPbI3 on a conductive substrate, inhibits the lattice expansion and contraction induced by light and heat, and then obtains a perovskite solar cell with high efficiency and stability.

[0007] The chalcogen ligand material designed in the present application has not only a higher solubility aromatic group (such as benzene ring), but also oxygen, sulfur, selenium, tellurium and other chalcogen elements, and halogen / pseudo halogen functional groups. Among them, the chalcogen elements have coordination bond effect with lead iodide, can react with lead iodide to generate lead acid salt and anchor at the perovskite grain boundary, and stabilize the perovskite lattice; the halogen / pseudo halogen functional groups are volatile, which can effectively regulate the growth kinetics of perovskite thin film during thermal annealing process, and prepare room temperature stable FAPbI3. Due to the synergistic effect of chalcogen elements and functional groups, the perovskite has the functions of adjusting crystal, releasing lattice stress and promoting transport.

[0008] The present application discloses a perovskite solar cell based on chalcogen ligand material, which comprises a perovskite thin film layer doped with chalcogen ligand material. As common sense, the solar cell also comprises a conventional conductive substrate, an electron transport layer, a hole transport layer and an anode.

[0009] The application discloses a preparation method of the perovskite solar cell based on the chalcogen ligand material, and comprises the following steps: preparing an electron transport layer on a conductive substrate; then spin-coating a perovskite precursor solution doped with the chalcogen ligand material on the electron transport layer, and then performing heat treatment to obtain a perovskite film layer; and then preparing a hole transport layer and an anode on the perovskite film in sequence to obtain the perovskite solar cell based on the chalcogen ligand material, which has room temperature stability and low lattice stress.

[0010] The application further discloses a day and night cycle stability test method for the perovskite solar cell, which comprises the following steps: testing the power of the perovskite solar cell under sunlight, and then avoiding light; and repeating the above test process to complete the day and night cycle stability test of the perovskite solar cell.

[0011] The application discloses a perovskite film based on a chalcogen ligand material.

[0012] The application discloses a preparation method of the perovskite film based on the chalcogen ligand material, which comprises the following steps: performing heat treatment on a perovskite precursor solution doped with the chalcogen ligand material to form a film, and obtaining the perovskite film based on the chalcogen ligand material.

[0013] The application discloses an application of the perovskite film based on the chalcogen ligand material in the preparation of a perovskite solar cell.

[0014] The application discloses an application of the chalcogen ligand material in the preparation of a perovskite solar cell or a perovskite film for the perovskite solar cell.

[0015] In the application, the heat treatment is 140-160 DEG C for 15-30 minutes; in the perovskite solution doped with the chalcogen ligand material, the doping concentration is 0.2-2.0 mg / mL -1 , preferably 0.5-1.0 mg / mL -1 .

[0016] In the application, the perovskite precursor solution is a solution containing all perovskite precursors, or a solution containing part of perovskite precursors and another solution containing the remaining part of perovskite precursors; the former is preferably prepared into a film by one-step spin coating and one-step spin coating anti-solvent method, and the latter is prepared into a film by two-step spin coating method.

[0017] As an example, the perovskite precursor solution is a solution containing part of the perovskite precursor (such as PbI2) and another solution containing the remaining part of the perovskite precursor (such as formamidinium iodide, FAI), the PbI2 solution doped with the chalcogen ligand material is spin-coated on the electron transport layer, and after annealing, the FAI solution is spin-coated, and then heat-treated to obtain a perovskite thin film layer; or the PbI2 solution is spin-coated on the electron transport layer, and after annealing, the FAI solution doped with the chalcogen ligand material is spin-coated, and then heat-treated to obtain a perovskite thin film layer. The concentration of PbI2 is 600-750 mg / mL; in the FAI solution doped with the chalcogen ligand material, the solvent is isopropanol, and the concentration of the FAI solution is 90-110 mg / mL. The ligand material doping concentration is 0.2-2.0 mg / mL -1 , preferably 0.5-1.0 mg / mL -1 .

[0018] In the present application, during the heat treatment process, the ligand material and the precursor material react to generate volatile substances (hydrochloric acid, etc.) and lead acid salts, effectively optimizing the crystallization process of the perovskite, and the room temperature stable pseudo-cubic FAPbI3 prepared avoids phase change during the day-night cycle; at the same time, the lead acid salt anchored at the grain boundary further inhibits the lattice expansion and contraction induced by light and temperature, thereby eliminating the lattice stress change of the perovskite during the day-night cycle and inhibiting the degradation of the perovskite. The present application prepares an electron transport layer on a conductive substrate, and subsequently prepares a hole transport layer on the perovskite layer and an anode on the hole transport layer, which are all prior art, to obtain a high-efficiency and stable perovskite solar cell.

[0019] The preparation method of the perovskite layer disclosed in the present application eliminates the periodic stress change of the perovskite lattice in the day-night cycle working mode, thereby enhancing the actual working life of the perovskite solar cell. Therefore, in the day-night cycle mode, the perovskite solar cell prepared based on the chalcogen ligand material has a T 80 life significantly improved by 10 times; at the same time, the device stability based on other ISOS protocol tests is also greatly improved.

[0020] In the present application, the chemical structural formula of the chalcogen ligand material is as follows:

[0021] ;

[0022] wherein A is a chalcogen element, preferably a chalcogen element containing a lone pair of electrons, such as oxygen, sulfur, selenium, and tellurium; X is a volatile halogen or pseudo-halogen, such as iodine, bromine, and amino; in the structural formula, the dotted line represents weak coordination, and the dot represents a free radical, which is a conventional representation method in the art and does not affect the understanding of those skilled in the art.

[0023] The application discloses a unique degradation mechanism of a perovskite solar cell in a day-night cycle mode for the first time, and emphasizes the necessity of stabilizing a lattice and eliminating lattice strain to enhance the actual working life of the perovskite solar cell. In particular, a series of chalcogen ligand materials are developed to eliminate lattice stress changes and stabilize the perovskite lattice. The ligand material forms a volatile substance in a thermal annealing process and a FAI reaction, optimizes the crystal growth kinetics of the perovskite, and obtains a room-temperature stable pseudo-cubic phase FAPbI3 with higher symmetry; in addition, the ligand material reacts with PbI2 to generate a plumbate and anchor at a grain boundary, further inhibits light and heat-induced lattice expansion and contraction, eliminates lattice stress changes, and thus obtains a high-efficiency and stable perovskite solar cell.

[0024] The application has the following beneficial effects:

[0025] 1. The application grows a perovskite lattice with high symmetry and low strain on a conductive substrate by doping chalcogen ligand materials in a perovskite precursor solution, and prepares a high-efficiency and stable perovskite solar cell based on this.

[0026] 2. The application ingeniously designs the chalcogen elements and volatile functional groups of the ligand material, and the two control perovskite crystallization and film morphology, greatly improve the lattice distortion of the perovskite film on the conductive substrate, and thus obtain a stable perovskite film on the conductive substrate.

[0027] 3. The application discloses a day-night cycle stability test method, in the day-night cycle mode, the service life of the perovskite solar cell prepared based on the chalcogen ligand material is significantly improved; at the same time, the stability of the device based on other ISOS protocol tests is also greatly improved.

[0028] 4. The preparation method of the application is simple, does not introduce additional interface layers or post-processing processes, and has excellent product performance, and is suitable for industrial production.

[0029] The above description is only a summary of the technical scheme of the application, in order to more clearly understand the technical means of the application, and the application can be implemented according to the content of the description, the following is a preferred embodiment of the application and the accompanying drawings are described in detail. The specific embodiment of the application is given in detail by the following examples and their accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The nuclear magnetic resonance spectrum of phenyl selenyl chloride (Ph-Se-Cl).

[0031] Figure 2 The stress change diagram of the perovskite film calculated by curvature measurement under continuous light and day-night cycle working modes.

[0032] Figure 3XRD patterns of perovskite wet films (before annealing) based on different doping amount of chalcogen ligand materials and corresponding peak intensity ratio analysis.

[0033] Figure 4 HR-TEM images of perovskite thin films based on doping chalcogen ligand materials.

[0034] Figure 5 Lead halide powders after reaction of ligand materials and PbI2 and corresponding XRD patterns.

[0035] Figure 6 Temperature dependent XRD patterns of perovskite thin films before and after doping chalcogen ligand materials.

[0036] Figure 7 In-situ GIWAXS data of perovskite thin films before and after doping chalcogen ligand materials and the changes of unit cell volume and half-peak width parameters of perovskite lattice during in-situ GIWAXS measurement.

[0037] Figure 8 Degradation mechanism of perovskite under day-night cycling mode and lattice parameters and spontaneous lattice stress of perovskite thin films before and after doping chalcogen ligand materials at room temperature.

[0038] Figure 9 Cross-sectional SEM images of perovskite solar cells before and after aging under continuous light and day-night cycling mode before and after doping chalcogen ligand materials.

[0039] Figure 10 Ion migration activation energy tests of perovskite solar cells before and after aging under continuous light and day-night cycling mode before and after doping chalcogen ligand materials.

[0040] Figure 11 Stability tests of perovskite solar cells under continuous light and day-night cycling mode (RT~55℃) before and after doping chalcogen ligand materials.

[0041] Figure 12 Stability tests of perovskite solar cells under day-night cycling mode (RT~85℃) before and after doping chalcogen ligand materials.

[0042] Figure 13 85℃ thermal stability tests of perovskite solar cells before and after doping chalcogen ligand materials.

[0043] Figure 14 Thermal cycling stability (RT~85℃) tests of perovskite solar cells according to ISOS-T-1 protocol before and after doping chalcogen ligand materials.

[0044] Figure 15Statistical chart of stability comparison of perovskite solar cells based on different perovskite components after doping chalcogen ligand materials under continuous light and day-night cycle mode (RT~55℃) (test for 108 hours or 9 day-night cycles).

[0045] Figure 16 Current-voltage curve of perovskite solar cells based on chalcogen ligand materials (effective area 0.062 cm 2 ). DETAILED DESCRIPTION

[0046] The present application first discloses the degradation mechanism of perovskite solar cells under day-night cycle operation mode. Through in-situ crystal analysis and carrier dynamics research of perovskite, it is found that under day-night cycle operation mode, the periodic light and temperature fluctuation makes the perovskite solar cell experience the expansion and contraction of the lattice synchronously during operation, which induces the cyclic change of the lattice stress. These periodic changes in lattice stress induce the generation and accumulation of perovskite deep level defects, which aggravate the ion migration behavior of perovskite, and accelerate the device performance degradation compared with continuous light. The present application develops a series of chalcogen ligand materials to eliminate the change of lattice stress and stabilize the perovskite lattice. Through the dual strategies of crystallization optimization and lattice anchoring, a higher symmetry room temperature stable pseudo-cubic phase FAPbI3 is obtained, which inhibits the light and heat induced lattice expansion and contraction and eliminates the change of lattice stress. The perovskite solar cells prepared based on this strategy have excellent photoelectric conversion efficiency (PCE) and stability, and the PCE is maintained at 90% of the initial value after 9 day-night cycles under day-night cycle operation mode T 80 The lifetime is significantly improved by 10 times; at the same time, the device stability based on various international summit agreements on organic photovoltaic stability (ISOS) tests is also greatly improved.

[0047] The perovskite solar cell based on chalcogen ligand material disclosed in the present application comprises a perovskite layer, and the preparation raw material of the perovskite layer comprises a chalcogen ligand material. Preferably, the preparation raw material of the perovskite layer comprises a perovskite precursor solution doped with a chalcogen ligand material.

[0048] Preferably, the chemical structural formula of the chalcogen ligand material is as follows:

[0049] ;

[0050] Wherein, X is halogen or pseudo-halogen substituent; A is a chalcogen element containing a lone pair of electrons.

[0051] The application prepares an electron transport layer on a conductive substrate; then a perovskite precursor solution doped with a chalcogen ligand material is spin-coated on the electron transport layer, and then heat treatment is performed to obtain a perovskite film layer; then a hole transport layer and an anode are sequentially prepared on the perovskite film to obtain a perovskite solar cell based on the chalcogen ligand material, which has room temperature stability and low lattice stress. Preferably, the heat treatment is 140-160℃ for 10-20 minutes.

[0052] In the application, the perovskite precursor solution is a solution containing all perovskite precursors, or a solution containing part of the perovskite precursors and another solution containing the remaining part of the perovskite precursors; the former is prepared by one-step spin coating, preferably one-step spin coating anti-solvent method, and the latter is prepared by two-step spin coating. This is a conventional method for preparing perovskite films, and the creativity of the application lies in doping the chalcogen ligand material without changing the raw materials of perovskite itself and the film preparation method.

[0053] Taking two groups of perovskite precursor solutions as examples, the details of each step in the preparation method of the efficient and stable perovskite solar cell based on the chalcogen ligand material are as follows:

[0054] (1) First, prepare PbI2 DMF solution doped with a chalcogen ligand material and FAI isopropyl alcohol solution; or prepare PbI2 DMF solution and FAI isopropyl alcohol solution doped with a chalcogen ligand material;

[0055] (2) Spin-coat a layer of SnO2 on a clean FTO, with a thickness of 10-20 nm;

[0056] (3) Spin-coat the prepared PbI2 solution on the SnO2 layer, anneal to obtain a lead iodide film, then spin-coat the FAI solution, and anneal to obtain a perovskite film with a thickness of 600-700 nm; or spin-coat the PbI2 solution on the SnO2 layer, then spin-coat the FAI solution doped with a chalcogen ligand material after annealing, and then heat treatment to obtain a perovskite film layer;

[0057] (4) Spin-coat Spiro-OMeTAD as a hole transport layer, with a thickness of 80-100 nm;

[0058] (5) The electrode is a gold electrode, which is deposited by a vacuum evaporation machine, with a thickness of 100 nm.

[0059] The application discloses three chemical structures of chalcogen ligand materials, and discloses a preparation method of a representative chalcogen ligand material as an example.

[0060] A method for preparing a chalcogen ligand material, phenyl selenyl chloride (Ph-Se-Cl), comprising the steps of adding dropwise a solution of sulfuryl chloride in an inert gas to a solution of diphenyl diselenide, followed by stirring the reaction at room temperature, and finally concentrating the resulting mixture under reduced pressure to obtain an orange solid which can be used without further purification.

[0061] A method for preparing a chalcogen ligand material, phenyl selenyl chloride (Ph-Se-Cl), comprising the steps of adding dropwise a solution of sulfuryl chloride in an inert gas to a solution of diphenyl diselenide, followed by stirring the reaction at room temperature, and finally concentrating the resulting mixture under reduced pressure to obtain an orange solid which can be used without further purification.

[0062] A method for preparing a chalcogen ligand material, phenyl selenyl chloride (Ph-Se-Cl), comprising the steps of adding dropwise a solution of sulfuryl chloride in an inert gas to a solution of diphenyl diselenide, followed by stirring the reaction at room temperature, and finally concentrating the resulting mixture under reduced pressure to obtain an orange solid which can be used without further purification.

[0063] The application will be described in detail below with reference to examples. The raw materials involved are all existing products, and the specific preparation method and performance test operation are conventional techniques; the FTO is routinely cleaned before use as a conductive substrate.

[0064] The photoelectric performance of the device was obtained by measuring the device using a source meter (Keithley 2400) under simulated 1 sun irradiance (100 mW cm -2 ) of AM 1.5G of a Newport xenon lamp, with a standard silicon cell with a KG-5 filter for light intensity calibration. The steady-state power conversion efficiency was calculated by measuring the steady photocurrent density at a constant bias voltage (Vmax point), with the effective area of the device corrected by an area-accurate light transmission hole (0.062 and 1.004 cm 2 ). Example 1

[0065] A method for preparing a chalcogen ligand material, phenyl selenyl chloride (Ph-Se-Cl), specifically comprising the steps of: adding dropwise a solution of diphenyl diselenide (1.56 mL, 5 mmol) in anhydrous dichloromethane (20 mL) into a 50 mL round-bottom flask at 0°C, the flask being filled with argon, and then adding dropwise sulfuryl chloride (0.67 mL, 5 mmol) after stirring; followed by further stirring at room temperature for 1 h; finally, concentrating the resulting mixture under reduced pressure to obtain an orange solid which can be used without further purification.

[0066] Other chalcogen ligand materials, such as phenyl selenyl chloride (Ph-Se-Cl), phenyl selenyl chloride (Ph-Te-Cl), can be prepared according to the above method.

[0067] Figure 1 Phenyl selenyl chloride (Ph-Se-Cl) was used as the chalcogenide ligand material in the following experiments unless otherwise specified. 1 HNMR chart and 13 C NMR chart. 1 H NMR (300 MHz, CDCl3):δ = 7.82-7.79 (m, 2H), 7.43-7.41 (m, 3H); 13 C NMR (151 MHz, CDCl3): δ = 134.4,131.7, 130.6, 129.6.

[0068] Phenyl selenyl chloride (Ph-Se-Cl) was used as the chalcogenide ligand material in the following experiments unless otherwise specified. Example Two

[0069] A method for preparing a perovskite film and a stress test of the film, comprising the following steps:

[0070] (1) Spin a layer of SnO2 on a clean FTO, using a tin dioxide dispersion liquid (7.5% aqueous colloidal), the spin speed is 3000 rpm, 150°C annealing for 30 min, the thickness is 15 nm;

[0071] (2) Spin the prepared PbI2 solution (the concentration of PbI2 is 692 mg mL -1 ) on SnO2, annealing to obtain a doped lead iodide film, the spin speed is 1500 rpm, 70°C annealing for 1 min; then spin FAI isopropanol solution (the concentration of FAI is 90 mg mL -1 ) on the dry PbI2 film, then annealing at 150°C for 15 min to obtain an undoped perovskite film, the thickness is 650 nm.

[0072] (3) Place the perovskite film in continuous light or diurnal cycle mode for stress evolution tracking test. In continuous light mode, the device is placed under 1 sun and the temperature control table is set at 25°C; in diurnal cycle mode, the device is placed under 1 sun, and after 30 minutes of light, it is restored in a dark environment for about 20 minutes (without bias), due to the heating of photo radiation, the device temperature fluctuates from ~55°C (light) to room temperature (dark state).

[0073] The prepared film is used for stress test, such as Figure 2The stress changes of perovskite films under continuous light and day-night cycle mode were calculated according to the curvature changes by measuring the curvature of perovskite films and substrates through a Linkam heating stage. The stress measurement shows that, in the continuous light mode, the stress of perovskite films is released from ~84 MPa to ~68 MPa within 4 hours as the light time increases, with the temperature fixed at room temperature; in the day-night cycle mode, the stress of perovskite films changes synchronously with the changes of light and temperature (the change value is ~40 MPa), indicating that the periodic changes of the stress of perovskite films accelerate the performance degradation of perovskite solar cells in the day-night cycle mode. Example Three

[0074] A preparation method of a perovskite film doped with a chalcogen ligand material, comprising the following steps:

[0075] (1) First, prepare a PbI2 DMF solution (the concentration of PbI2 is 692 mg mL -1 ) and a FAI isopropanol solution doped with different contents of chalcogen ligand materials (0-2 mg mL -1 ) (the concentration is 90 mg mL -1 );

[0076] (2) Use a two-step method to prepare a perovskite layer, spin-coat the prepared PbI2 solution on a clean FTO substrate, and anneal to obtain a PbI2 film, with a rotation speed of 1500 rpm and annealing at 70°C for 1 min; then spin-coat the FAI isopropanol solution on the dry PbI2 film to prepare a perovskite film without heat annealing treatment;

[0077] The prepared unannealed perovskite film is subjected to XRD testing, as shown in Figure 3 , with the increase of the doping concentration of Ph-Se-Cl, the peak intensity ratio of α-FAPbI3 / PbI2 and the intermediate phase / PbI2 increases, indicating that Ph-Se-Cl promotes the phase transition of PbI2 to the perovskite α phase, optimizes the crystal orientation of the perovskite, and helps to improve the quality of the perovskite film. Example Four

[0078] A preparation method of a perovskite film doped with a chalcogen ligand material, comprising the following steps:

[0079] (1) First, prepare a PbI2 DMF solution (the concentration of PbI2 is 692 mg mL -1 ) and a FAI isopropanol solution doped with a chalcogen ligand material (0.5 mg mL -1 ) (the concentration is 90 mg mL -1 );

[0080] (2) Two-step method was used to prepare perovskite layer. PbI2 solution was spin-coated on clean FTO substrate, and PbI2 thin film was obtained by annealing at 70°C for 1 min with a rotation speed of 1500 rpm; then FAI isopropanol solution was spin-coated on the dried PbI2 thin film;

[0081] (3) Then the doped perovskite thin film was obtained by annealing at 150°C for 15 min.

[0082] The prepared thin film was used for HR-TEM test, as shown in Figure 4 According to the FFT analysis of the HR-TEM image of the perovskite thin film doped with Ph-Se-Cl, the lattice spacing of region 1 and region 2 was 3.2 and 7.4 Å respectively, which was attributed to the (002) crystal plane of α-FAPbI3 and the new substance respectively, indicating that Ph-Se-Cl could react with PbI2 to generate a lead salt.

[0083] A preparation method of a Ph-Se-Cl that can react with PbI2 to generate a new substance, comprising the following steps:

[0084] (1) First, 1.5 M PbI2 and 1.5 M Ph-Se-Cl powders were dissolved in 1 mL DMF and stirred overnight at 50°C;

[0085] (2) Then the solution was filtered and transferred to a 4 mL brown bottle containing 2 mL tetrahydrofuran solution and sealed;

[0086] (3) Yellow powder precipitated with the slow diffusion of tetrahydrofuran vapor.

[0087] In order to further explore the composition of the light yellow powder, the powder was subjected to XRD test, as shown in Figure 5 The powder showed a diffraction peak near 7.03°, indicating the generation of a lead salt. This peak also matched the lattice spacing obtained by HR-TEM test. In combination with Example Three, Ph-Se-Cl had two effects in the perovskite thin film: first, Ph-Se-Cl reacted with FAI to form a volatile substance during thermal annealing, optimizing the crystal growth kinetics of the perovskite; second, Ph-Se-Cl reacted with PbI2 to generate a lead salt and anchor at the grain boundary, improving the lattice stability of the perovskite. Example Five

[0088] A preparation method of a perovskite thin film doped with a chalcogen ligand material, comprising the following steps:

[0089] (1) First, FAI isopropanol solution (concentration of 90 mg mL -1 ) doped with chalcogen ligand material (0.5 mg mL -1Undoped FAI isopropanol solution (concentration 90 mg / mL) -1 ) and PbI2 DMF solution (PbI2 concentration is 692 mg / mL) -1 );

[0090] (2) A two-step method was used to prepare the perovskite layer. The prepared PbI2 solution was spin-coated onto a clean FTO substrate and annealed to obtain a PbI2 film at 1500 rpm and 70°C for 1 min. Then, an undoped or chalcogenide-doped FAI isopropanol solution was spin-coated onto the dried PbI2 film and annealed at 150°C for 15 min to obtain the perovskite film.

[0091] (3) XRD tests were performed on the perovskite films during the heat annealing cooling process (150℃, 125℃, 100℃, 75℃, 50℃, 25℃).

[0092] like Figure 6 The figure shows the XRD pattern of the perovskite film. It can be seen from the figure that the peak around 28° of the undoped perovskite film is symmetrical at 150°. When the temperature drops from 150° to 25°, the peak shape of the (004) / (220) characteristic diffraction peak becomes asymmetrical, and the peak of the (002) / (110) characteristic diffraction peak is oriented towards the higher angle, indicating that the lattice volume shrinks during the cooling process and the lattice is distorted. However, the doped perovskite film maintains a highly symmetrical pseudo-cubic phase during the thermal annealing cooling process, which suppresses the temperature-induced lattice phase transition. Example 6

[0093] A method for preparing a perovskite thin film doped with chalcogenide ligands includes the following steps:

[0094] (1) First, prepare a material doped with chalcogenide ligands (0.5 mg / mL). -1 FAI isopropanol solution (concentration 90 mg / mL) -1 Undoped FAI isopropanol solution (concentration 90 mg / mL) -1 ) and PbI2 DMF solution (PbI2 concentration is 692 mg / mL) -1 );

[0095] (2) A two-step method was used to prepare the perovskite layer. The prepared PbI2 solution was spin-coated onto a clean silicon substrate and annealed to obtain a PbI2 film at 1500 rpm and 70°C for 1 min. Then, an undoped or chalcogenide-doped FAI isopropanol solution was spin-coated onto the dried PbI2 film and annealed at 150°C for 15 min to obtain the perovskite film.

[0096] (3) In-situ GIWAXS test was performed on perovskite films (simulated day-night cycle mode), and the specific scheme is as follows: the cycle starts from the dark state at room temperature, then the light source (cold light source) is started, and the substrate temperature is raised to ~55℃ within 5 minutes. The perovskite film is monitored for 90 minutes under the combined action of light and temperature. Then the light source is turned off and the substrate temperature control is stopped, and it is cooled to room temperature within 30 minutes. This is one cycle, and 2 cycles are detected.

[0097] As shown in Figure 7 , with the increase of monitoring time, the (002) & (110) diffraction peaks of the undoped perovskite film shift to smaller q values, indicating that the perovskite lattice expands, and then q values tend to be stable; when the sample is cooled to room temperature, the q value returns to the initial state, and the perovskite lattice shrinks. According to the test results of in-situ GIWAXS, the unit cell volume and the half-peak width change of perovskite were calculated, and it was found that the unit cell volume of perovskite changed greatly (~0.48%) under the day-night cycle mode, and the half-peak width of (002) & (110) characteristic peaks increased and decreased synchronously with the change of light and temperature, indicating that the perovskite lattice would expand and shrink under the day-night cycle mode. However, the (002) & (110) diffraction peaks of the doped perovskite film hardly shift, and the calculated perovskite unit cell volume and peak width change are also very small (~0.04%), indicating that Ph-Se-Cl effectively inhibits the volume change of the lattice and stabilizes the perovskite lattice.

[0098] Table 1 Normalized lattice parameters and calculated spontaneous strain of perovskite films

[0099]

[0100] By analyzing the crystal structure of perovskite at room temperature, as shown in Figure 8 and Table 1, it is found that the perovskite doped with chalcogen ligand material presents a pseudo-cubic phase at room temperature, while the undoped perovskite presents a γ phase at room temperature. Then the lattice stress generated in the phase transition of perovskite was calculated, and it was found that the lattice spontaneous stress (e tet and e orth values) of perovskite doped with chalcogen ligand material decreased, indicating that Ph-Se-Cl effectively released the lattice spontaneous strain, which helped to inhibit the periodic lattice stress change caused by the phase transition of perovskite under the day-night cycle mode. Example Seven

[0101] A preparation method of a perovskite solar cell, comprising the following steps:

[0102] (1) First, prepare a chalcogen ligand material (0.5 mg mL -1FAI isopropanol solution (concentration of 90 mg mL -1 , undoped FAI isopropanol solution (concentration of 90 mg mL -1 ) and PbI2 DMF solution (concentration of PbI2 of 692 mg mL -1 );

[0103] (2) Spin a layer of SnO2 on a clean 1.5*1.5 cm 2 FTO conductive substrate, using a tin dioxide dispersion (7.5% hydrogel), the spin speed is 3000 rpm, 150°C annealing for 30 min, thickness is 15 nm;

[0104] (3) Use a two-step method to prepare a perovskite layer, spin the prepared PbI2 solution on SnO2, anneal to obtain a lead iodide film, the spin speed is 1500 rpm, 70°C annealing for 1 min, then spin the undoped or doped chalcogen ligand material FAI isopropanol solution on the dry PbI2 film; then anneal on a hot stage at 150°C for 15 min to obtain a perovskite film, the film thickness is 650 nm;

[0105] (4) Prepare Spiro-OMeTAD as a hole transport layer on the perovskite film, the solvent is chlorobenzene, the concentration is 72.3 mg mL -1 , the spin speed is 3000 rpm, the thickness is 90 nm;

[0106] (5) Evaporate gold electrodes in a vacuum coating machine, the thickness is 100 nm, and finally obtain a doped flexible perovskite solar cell with an effective area of 0.062 cm 2 ;

[0107] (6) Perform aging tests on the above device under continuous light working mode or day-night cycle working mode; under continuous light working mode conditions, the device is placed under 1 sun and tracked at the maximum power point, and due to photo-induced radiation heating, the device temperature gradually rises from room temperature to ~55°C; under day-night cycle mode conditions, the device is placed under 1 sun, and after 12 hours of light (tracked at the maximum power point), it is restored in a dark environment for 12 hours (without bias), and due to photo-induced radiation heating, the device temperature fluctuates from ~55°C (light) to room temperature (dark state); the perovskite film is aged for 156 h and 13 cycles (same light time) under continuous light and day-night cycle working modes, respectively.

[0108] Perform cross-section SEM tests on the aged device, such as Figure 9As shown, undoped perovskite films aged under both operating modes exhibited pores and interface cracks, indicating that the performance degradation of the device is related to strain-induced plastic deformation of the film. Furthermore, the deformation and degradation of the film were more severe under the day-night cycling mode, suggesting that the day-night cycling mode accelerates the degradation of perovskite. However, perovskite films doped with chalcogenide ligands showed no pores or cracks and exhibited uniform and dense morphology after aging under both operating modes. This indicates that Ph-Se-Cl can effectively release the lattice stress of the perovskite film, suppress lattice volume changes, and significantly improve the stability of the perovskite film, especially its stability under day-night cycling. Example 8

[0109] A method for fabricating a perovskite solar cell includes the following steps:

[0110] (1) First, prepare a material doped with chalcogenide ligands (0.5 mg / mL). -1 FAI isopropanol solution (concentration 90 mg / mL) -1 Undoped FAI isopropanol solution (concentration 90 mg / mL) -1 ) and PbI2 DMF solution (PbI2 concentration is 692 mg / mL) -1 );

[0111] (2) In a clean 1.5×1.5 cm 2 A layer of SnO2 was spin-coated onto an FTO conductive substrate using a tin dioxide dispersion (7.5% aqueous colloid). The spin-coating speed was 3000 rpm, and the substrate was annealed at 150℃ for 30 min to a thickness of 15 nm.

[0112] (3) A two-step method was used to prepare the perovskite layer. The prepared PbI2 solution was spin-coated onto SnO2 and annealed to obtain a lead iodide film at 1500 rpm and 70°C for 1 min. Then, an undoped or chalcogenide-doped FAI isopropanol solution was spin-coated onto the dried PbI2 film. Finally, the film was annealed on a hot plate at 150°C for 15 min to obtain a perovskite film with a thickness of 650 nm.

[0113] (4) Spiro-OMeTAD was prepared as a hole transport layer on a perovskite film using chlorobenzene as the solvent at a concentration of 72.3 mg / mL. -1 The spin coating speed was 3000 rpm, and the thickness was 90 nm.

[0114] (5) The thin film was placed in a vacuum coating machine to deposit gold electrodes with a thickness of 100 nm, resulting in an effective area of ​​0.062 cm². 2 Doped flexible perovskite solar cells;

[0115] (6) The above devices were subjected to aging tests in continuous illumination mode or day and night cycle mode. In continuous illumination mode, the device was placed under one sun and tracked at the maximum power point. Due to photoradiative heating, the device temperature gradually rose from room temperature to ~55℃. In day and night cycle mode, the device was placed under one sun and illuminated for 12 hours (tracking test at the maximum power point) and then restored in the dark for 12 hours (without bias). Due to photoradiative heating, the device temperature fluctuated from ~55℃ (illuminated) to room temperature (dark state).

[0116] The ion migration activation energy is applied to the aged device. E a ) test, such as Figure 10 As shown, the initial state of an undoped perovskite solar cell E a The voltage is ~0.25 eV. After aging under continuous light for 84 hours, E a It dropped to ~0.19 eV, and after further aging for 168 hours, E a The value dropped to ~0.18 eV, indicating that with increasing aging time, E a The downward trend gradually leveled off; however, during the diurnal aging process, E a The light intensity decreased continuously after 7 aging cycles (84 hours of light exposure). E a It dropped to ~0.16 eV and was further aged for 14 cycles (168 hours of light exposure). E a Dropped to ~0.13 eV. (During day / night cycle mode) E a The rapid decline indicates that the periodic changes in perovskite lattice stress accelerate ion migration in perovskite solar cells, leading to faster performance degradation.

[0117] The initial perovskite solar cell after doping with chalcogenide ligands E a The voltage increased from ~0.25 eV to ~0.38 eV; compared to undoped perovskite solar cells during aging... E a The continuous decline in [something] indicates that perovskite solar cells doped with chalcogenide ligands age under continuous illumination and day-night cycling modes. E aThe lattice stress of the perovskite thin film is effectively released by the chalcogenide ligand material, the perovskite lattice volume change is inhibited, the ion migration behavior of the perovskite solar cell is inhibited, and the stability of the perovskite solar cell is significantly improved. Example Nine

[0118] A preparation method of a perovskite solar cell, comprising the following steps:

[0119] (1) First, prepare a FAI isopropanol solution (concentration: 90 mg / mL -1 ) doped with a chalcogenide ligand material (0.5 mg / mL -1 ), an undoped FAI isopropanol solution (concentration: 90 mg / mL -1 ), and a PbI2 DMF solution (concentration of PbI2: 692 mg / mL -1 );

[0120] (2) Spin a layer of SnO2 on a clean 1.5*1.5 cm 2 FTO conductive substrate, using a tin dioxide dispersion liquid (7.5% hydrogel), the spin speed is 3000 rpm, and the thickness is 15 nm after annealing at 150°C for 30 min;

[0121] (3) Prepare the perovskite layer by using a two-step method, spin the prepared PbI2 solution on the SnO2, anneal to obtain a lead iodide thin film, the spin speed is 1500 rpm, and the annealing temperature is 70°C for 1 min, then spin the undoped or doped chalcogenide ligand material FAI isopropanol solution on the dry PbI2 thin film; then anneal at 150°C for 15 min on a hot stage to obtain a perovskite thin film, and the thickness is 650 nm;

[0122] (4) Prepare Spiro-OMeTAD as a hole transport layer on the perovskite thin film, the solvent is chlorobenzene, the concentration is 72.3 mg / mL -1 , the spin speed is 3000 rpm, and the thickness is 90 nm;

[0123] (5) Evaporate a gold electrode on the thin film in a vacuum coating machine, the thickness is 100 nm, and finally obtain a doped flexible perovskite solar cell with an effective area of 0.062 cm 2 ;

[0124] (6) The above devices were subjected to aging tests in continuous illumination mode or day and night cycle mode. In continuous illumination mode, the device was placed under one sun and tracked at the maximum power point. Due to photoradiative heating, the device temperature gradually rose from room temperature to ~55℃. In day and night cycle mode, the device was placed under one sun and illuminated for 12 hours (tracking test at the maximum power point) and then restored in the dark for 12 hours (without bias). Due to photoradiative heating, the device temperature fluctuated from ~55℃ (illuminated) to room temperature (dark state).

[0125] like Figure 11 As shown, the perovskite solar cell doped with chalcogenide ligands retained over 90% of its initial power efficiency (PCE) after 1000 hours of continuous illumination, while the undoped perovskite solar cell retained only ~44% of its initial PCE after 375 hours. More importantly, the stability of the perovskite solar cell doped with chalcogenide ligands was also significantly improved under day-night cycling: after 43 cycles of aging, the perovskite solar cell doped with chalcogenide ligands retained over 80% of its initial PCE, while the undoped perovskite solar cell retained only ~39% of its initial PCE after 13 cycles. This is one of the best stability results among perovskite solar cells based on Spiro-OMeTAD HTL. Example 10

[0126] A method for fabricating a perovskite solar cell includes the following steps:

[0127] (1) First, prepare a material doped with chalcogenide ligands (0.5 mg / mL). -1 FAI isopropanol solution (concentration 90 mg / mL) -1 Undoped FAI isopropanol solution (concentration 90 mg / mL) -1 ) and PbI2 DMF solution (PbI2 concentration is 692 mg / mL) -1 );

[0128] (2) In a clean 1.5×1.5 cm 2 A layer of SnO2 was spin-coated onto an FTO conductive substrate using a tin dioxide dispersion (7.5% aqueous colloid). The spin-coating speed was 3000 rpm, and the substrate was annealed at 150℃ for 30 min to a thickness of 15 nm.

[0129] (3) A two-step method was used to prepare the perovskite layer. The prepared PbI2 solution was spin-coated onto SnO2 and annealed to obtain a lead iodide film at 1500 rpm and 70°C for 1 min. Then, an undoped or chalcogenide-doped FAI isopropanol solution was spin-coated onto the dried PbI2 film. Finally, the film was annealed on a hot plate at 150°C for 15 min to obtain a perovskite film with a thickness of 650 nm.

[0130] (4) BDT-DPA-F was prepared as a hole transport layer on a perovskite film. The solvent was chlorobenzene with a concentration of 10.0 mg / mL. -1 The spin coating speed was 3000 rpm, and the thickness was 40 nm.

[0131] (5) The thin film was placed in a vacuum coating machine to deposit gold electrodes with a thickness of 100 nm, resulting in an effective area of ​​0.062 cm². 2 Doped flexible perovskite solar cells;

[0132] (6) The above devices were subjected to aging tests in different modes: the thermal stability and thermal cycling stability of the perovskite solar cells were tested according to the ISOS-D-2 and ISOS-T-1 stability protocols; for the stability under the day and night cycle working mode, the device was placed under one sun for 12 hours of illumination (tracking test at maximum power point) and then restored in the dark for 12 hours (no bias voltage), and the device temperature fluctuated from ~85℃ (illuminated) to room temperature (dark state).

[0133] like Figure 12 As shown, perovskite solar cells doped with chalcogenide ligands retained over 96% of their initial PCE after 25 24-hour cycles, while undoped perovskite solar cells retained only ~27% of their initial PCE; Figure 13 As shown, the PCE of perovskite solar cells doped with chalcogenide ligands exhibits very low degradation (~5%) after 1000 h of thermal aging at 85°C, while the PCE of undoped perovskite solar cells degrades by ~20% under the same conditions; Figure 14 As shown, in thermal cycling aging measurements, the perovskite solar cells doped with chalcogenide ligands retained over 96% of their initial PCE after 25 cycles of aging, both at 85°C and at room temperature. In contrast, undoped perovskite solar cells retained only ~80% and ~84% of their initial PCE, respectively. These stability assessment results for perovskite solar cells under different stability test conditions demonstrate that the crystallization optimization and lattice anchoring strategies of chalcogenide ligands can significantly improve the stability of perovskite solar cells under various aging conditions, greatly promoting the commercialization of perovskite solar cells. Example 11

[0134] A method for preparing a perovskite solar cell, comprising the following steps:

[0135] (1) First, prepare a FAI isopropanol solution (concentration of 90 mg mL -1 ) doped with a chalcogen ligand material (0.5 mg mL -1 ), a non-doped FAI isopropanol solution (concentration of 90 mg mL -1 ), and a PbI2 DMF solution (concentration of PbI2 of 692 mg mL -1 );

[0136] (2) Spin a layer of SnO2 on a clean 1.5 x 1.5 cm 2 FTO conductive substrate, using a tin dioxide dispersion (7.5% hydrogel), spin at a speed of 3000 rpm, anneal at 150°C for 30 min, thickness of 15 nm;

[0137] (3) Use a two-step method to prepare a perovskite layer, spin the prepared PbI2 solution on the SnO2, anneal to obtain a lead iodide film, spin at a speed of 1500 rpm, anneal at 70°C for 1 min, then spin the non-doped or doped chalcogen ligand material FAI isopropanol solution on the dry PbI2 film; then anneal at 150°C on a hot stage for 15 min to obtain a perovskite film, thickness of 650 nm;

[0138] (4) Prepare Spiro-OMeTAD as a hole transport layer on the perovskite film, solvent is chlorobenzene, concentration of 72.3 mg mL -1 , spin at a speed of 3000 rpm, thickness of 90 nm;

[0139] (5) Evaporate a gold electrode in a vacuum coating machine, thickness of 100 nm, finally obtain a doped flexible perovskite solar cell with an effective area of 0.062 cm 2 .

[0140] A method for preparing a perovskite solar cell, comprising the following steps:

[0141] (1) First, prepare a FAI isopropanol solution (concentration of 90 mg mL -1FAI, MAI and MACl isopropanol solution (FAI 90 mg, MAI 6.39 mg, MACl 9 mg dissolved in 1 mL IPA solution), undoped FAI, MAI and MACl isopropanol solution (FAI 90 mg, MAI 6.39 mg, MACl 9 mg dissolved in 1 mL IPA solution) and PbI2 DMF solution (the concentration of PbI2 is 692 mg mL -1 );

[0142] (2) Spin-coat a layer of SnO2 on a clean 1.5 x 1.5 cm 2 FTO conductive substrate, using a tin dioxide dispersion (7.5% hydrogel), the spin-coating speed is 3000 rpm, 150°C annealing for 30 min, the thickness is 15 nm;

[0143] (3) Use a two-step method to prepare a perovskite layer, spin-coat the prepared PbI2 solution on SnO2, anneal to obtain a lead iodide film, the spin-coating speed is 1500 rpm, 70°C annealing for 1 min, then spin-coat undoped or doped with chalcogen ligand material FAI, MAI and MACl isopropanol solution on the dry PbI2 film; then anneal on a hot stage at 150°C for 15 min to obtain a perovskite film, the thickness is 550 nm;

[0144] (4) Prepare Spiro-OMeTAD as a hole transport layer on the perovskite film, the solvent is chlorobenzene, the concentration is 72.3 mg mL -1 , the spin-coating speed is 3000 rpm, the thickness is 90 nm;

[0145] (5) Evaporate gold electrodes in a vacuum coating machine, the thickness is 100 nm, finally obtain a doped flexible perovskite solar cell with an effective area of 0.062 cm 2 .

[0146] A preparation method of a perovskite solar cell, comprising the following steps:

[0147] (1) First, prepare a perovskite precursor solution which is undoped and doped with chalcogen ligand material (0.5 mg mL -1 );

[0148] (2) Spin-coat a layer of SnO2 on a clean 1.5 x 1.5 cm2 SnO2 layer was spin-coated on the FTO conductive substrate using a tin dioxide dispersion liquid (7.5% hydrogel), the spin-coating speed was 3000 rpm, 150°C annealing for 30 min, and the thickness was 15 nm;

[0149] (3) The perovskite layer was prepared by one-step method, the prepared perovskite precursor solution was coated on SnO2, first spin-coated at 1000 rpm for 10 s, then spin-coated at 5000 rpm for 30 s; 120 µL of chlorobenzene was spin-coated onto the film as an anti-solvent at 15 s, and then the perovskite film was transferred to an air environment (humidity about 20%), and 105°C thermal annealing for 30 min, and the thickness was 550 nm;

[0150] (4) Spiro-OMeTAD was prepared as a hole transport layer on the perovskite film, the solvent was chlorobenzene, the concentration was 72.3 mg mL -1 -1, and the spin-coating speed was 3000 rpm, and the thickness was 90 nm;

[0151] (5) The film was placed in a vacuum coating machine to evaporate gold electrode, the thickness was 100 nm, and finally the effective area of the doped flexible perovskite solar cell was 0.062 cm 2 .

[0152] The above device was aged under continuous light working mode or day-night cycle working mode; under continuous light working mode, the device was placed under 1 sun and tracked at the maximum power point, and due to photo-induced radiation heating, the device temperature gradually increased from room temperature to ~55°C; under day-night cycle mode, the device was placed under 1 sun, and after 12 hours of light (tracked at the maximum power point), it was recovered in the dark environment for 12 hours (without bias), and due to photo-induced radiation heating, the device temperature fluctuated from ~55°C (light) to room temperature (dark state).

[0153] Three different components of perovskite solar cells were aged under continuous light and day-night cycle working mode for 108 h or 9 day-night cycles (same light time), as shown in Figure 15 , after doping with sulfur group ligand material, the FAPbI3, FA 0.92 MA 0.08 PbI3 and Cs 0.05 FA 0.7 MA 0.25 PbI 2.6 Br 0.4The stability of the active layer component perovskite solar cell is enhanced in both working modes (high PCE retention rate), which indicates that the crystallization regulation and lattice anchoring dual strategies based on sulfide ligand material effectively slow down the perovskite degradation caused by lattice stress and have universality, laying a solid foundation for the commercial development of perovskite solar cells. Example twelve

[0154] A method for preparing a high-efficiency perovskite solar cell (effective area 0.062 cm 2 ) includes the following steps:

[0155] (1) First, prepare a FAI isopropanol solution (concentration 90 mg mL -1 ) doped with sulfide ligand material (0.5 mg mL -1 ), a FAI isopropanol solution (concentration 90 mg mL -1 ) without doping, and a PbI2 DMF solution (concentration of PbI2 692 mg mL -1 );

[0156] (2) Spin a layer of SnO2 on a clean 1.5*1.5 cm 2 FTO conductive substrate, using a tin dioxide dispersion (7.5% hydrogel), the spin speed is 3000 rpm, 150°C annealing for 30 min, thickness is 15 nm;

[0157] (3) Use a two-step method to prepare a perovskite layer, spin the prepared PbI2 solution on SnO2, anneal to obtain a lead iodide film, the spin speed is 1500 rpm, 70°C annealing for 1 min, then spin the FAI isopropanol solution without doping or doped with sulfide ligand material on the dry PbI2 film; then anneal on a hot stage at 150°C for 15 min to obtain a perovskite film, thickness is 650 nm;

[0158] (4) Prepare Spiro-OMeTAD as a hole transport layer on the perovskite film, the solvent is chlorobenzene, the concentration is 72.3 mg mL -1 , the spin speed is 3000 rpm, the thickness is 90 nm;

[0159] (5) Evaporate gold electrodes in a vacuum coating machine, thickness is 100 nm, finally obtain a doped flexible perovskite solar cell with an effective area of 0.062 cm 2 .

[0160] The performance of the above perovskite solar cell is shown in Figure 16 (perovskite solar cell current-voltage curve) and Table 2, light intensity is AM1.5G 100 mW cm-2 .

[0161] Table 2 Photovoltaic parameters of perovskite solar cells

[0162]

[0163] Different from the current developed perovskite additive strategy, the present application has the following characteristics:

[0164] (1) Most of the current developed additive strategies are aimed at solving the stability problem of perovskite solar cells under specific aging conditions, and there are few studies on improving the service life of perovskite solar cells under day-night cycle working mode.

[0165] (2) Most of the current developed additive strategies have a specific function, such as defect passivation, crystallization regulation or lattice anchoring. In combination with the above examples, the sulfide ligand material developed by the present application has a dual function: first, Ph-Se-Cl reacts with FAI to form volatile substances during thermal annealing, optimizing the crystal growth kinetics of perovskite and obtaining a higher-symmetry room-temperature stable pseudo-cubic phase FAPbI3; in addition, the ligand material reacts with PbI2 to generate lead acid salt and anchor at the grain boundary, further inhibiting the lattice expansion and contraction induced by light and heat, and eliminating the lattice stress change. This dual strategy stabilizes the perovskite lattice from the root and comprehensively improves the stability of perovskite solar cells.

[0166] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A perovskite solar cell based on chalcogenide ligand materials, characterized in that, The perovskite thin film layer includes a chalcogenide ligand-doped material; the precursor of the perovskite thin film layer includes FAI; the chemical structural formula of the chalcogenide ligand material is as follows: ； Where A represents a chalcogenide; X represents a halogen or pseudohalogen.

2. The perovskite solar cell based on chalcogenide ligand materials according to claim 1, characterized in that, Pseudohalogens are amino groups.

3. The method for preparing the perovskite solar cell based on chalcogenide ligand materials according to claim 1, comprising the following steps: An electron transport layer is prepared on a conductive substrate; then a perovskite precursor solution doped with chalcogenide ligands is spin-coated onto the electron transport layer, followed by heat treatment to obtain a perovskite thin film; then a hole transport layer and an anode are prepared sequentially on the perovskite thin film to obtain a perovskite solar cell based on chalcogenide ligands.

4. A perovskite thin film based on chalcogenide ligand materials, characterized in that, The chemical structural formula of the chalcogenide ligand material is as described in claim 1.

5. The method for preparing the perovskite thin film based on chalcogenide ligands as described in claim 4 includes the following steps: heat-treating a perovskite precursor solution doped with chalcogenide ligands to form a film, thereby obtaining a perovskite thin film based on chalcogenide ligands.

6. The preparation method according to claim 3 or 5, characterized in that, The heat treatment is carried out at 140–160℃ for 15–30 minutes; the doping concentration in the perovskite solution doped with chalcogenide ligands is 0.2–2.0 mg / mL.

7. The application of the perovskite solar cell based on chalcogenide ligands as described in claim 1 in the fabrication of solar energy devices.

8. The application of the perovskite thin film based on chalcogenide ligands as described in claim 4 in the preparation of perovskite solar cells.

9. The use of the chalcogenide ligand material of claim 1 in the preparation of perovskite solar cells or perovskite thin films for perovskite solar cells.

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