Perovskite solar cell with polyanion buffer layer and preparation method thereof

Abstract

The application provides a perovskite solar cell containing a polyanion buffer layer and a preparation method thereof. The perovskite solar cell of the application introduces a PSTFSIK buffer layer on a PEDOT hole transport layer, which can form a strong chemical bond with a perovskite layer, enhances the binding force of the hole transport layer and the buried interface of the perovskite, and the strong interaction helps to stabilize the interface and inhibit the degradation of the interface; the introduction of the PSTFSIK buffer layer effectively inhibits the process of Sn 2+ oxidation to Sn 4+ in a tin-lead perovskite, reduces the defect state density; the PSTFSIK layer can regulate the crystallization process of the tin-lead perovskite, and obtain a more flat and high-quality perovskite film. The PSTFSIK layer can adjust the surface work function and energy level of PEDOT, so that the HOMO energy level of PEDOT is more matched with the valence band of the perovskite, the energy barrier of hole transport is reduced, the extraction of interface holes is promoted, and the non-radiative recombination loss of the interface is reduced.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and in particular to a perovskite solar cell containing a polyanion buffer layer and its preparation method. Background Technology

[0002] Monolithic all-perovskite tandem solar cells, consisting of a wide bandgap (WBG, 1.7–1.9 eV) top cell and a narrow bandgap (NBG, 1.2–1.3 eV) bottom cell, have attracted widespread research attention in recent years due to their high efficiency and diverse device structures. However, despite their high efficiency, stability remains a challenge for the practical application of both narrow bandgap perovskite and all-perovskite tandem solar cells.

[0003] Performance degradation associated with material and interface degradation within devices is a key issue that needs to be addressed to extend device lifetime. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is known for its high mobility and ease of processing, particularly in tin-lead narrow bandgap perovskite solar cells, where it is the most widely used hole transport layer. However, the hygroscopicity and acidity of PEDOT:PSS inevitably cause serious damage to the stability of narrow bandgap tin-lead perovskite in all-perovskite tandem solar cells. Acidic PEDOT:PSS leads to perovskite film degradation accompanied by iodine (I2) formation and accelerates Sn... 2+ Oxidation of the tin-lead perovskite at the buried interface severely impairs the long-term stability of the device. 4+ One possible pathway for defect formation is the generation of I2 driven by the acidic PEDOT:PSS hole transport layer, which then rapidly oxidizes the tin-lead perovskite. These defects act as recombination centers for photogenerated carriers, further impacting device performance.

[0004] Neutral PEDOT can fundamentally solve the perovskite degradation problem caused by the acidity of the hole transport layer, thus significantly improving the stability of devices based on PEDOT hole transport layers. However, the efficiency of tin-lead perovskite solar cells based on PEDOT hole transport layers is generally low. This is due to the poor interfacial bonding between the PEDOT hole transport layer and the perovskite layer, which leads to interface defects that exacerbate nonradiative recombination. Polyanionic PEDOT and perovskite precursor Sn... 2+ The strong interactions between the two layers induce rapid and uneven crystallization of tin-lead perovskite. Furthermore, the mismatched energy level arrangement between the PEDOT hole transport layer and the perovskite layer leads to carrier transport losses, affecting the photovoltaic performance of the device.

[0005] Therefore, while maintaining the stability of the hole transport layer itself, enhancing the bonding between the hole transport layer and the perovskite interface to suppress interface degradation and unfavorable side reactions, and establishing a favorable energy level arrangement, is of great significance for synergistically achieving efficient and stable narrow bandgap perovskite solar cells and all-perovskite tandem solar cells. Summary of the Invention

[0006] To address the aforementioned technical deficiencies, this invention provides a perovskite solar cell containing a polyanion buffer layer and its fabrication method. This invention introduces a PSTFSIK polyanion buffer layer onto the PEDOT hole transport layer, which can form strong chemical bonds with the perovskite layer, significantly enhancing the bonding force between the hole transport layer and the perovskite buried interface. This strong interaction helps stabilize the interface and inhibit interface degradation.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a perovskite solar cell containing a polyanion buffer layer, comprising a substrate, a hole transport layer, a polyanion buffer layer, a perovskite active layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode stacked sequentially.

[0009] The hole transport layer is a neutral PEDOT layer;

[0010] The polyanion buffer layer material is poly[potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imine], and its chemical formula is shown below:

[0011]

[0012] Where n≥1, and n is a positive integer.

[0013] Preferably, the preparation method of the poly[4-styrenesulfonyl (trifluoromethylsulfonyl)imine potassium salt] includes:

[0014] Potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide was added to water, followed by an initiator, and a polymerization reaction was carried out under an inert atmosphere to obtain poly[4-styrenesulfonyl (trifluoromethylsulfonyl)imide potassium salt].

[0015] Preferably, the method for preparing the potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imine includes:

[0016] By reacting 4-styrenesulfonyl chloride with trifluoromethylsulfonamide, 4-styrenesulfonyl (trifluoromethylsulfonyl) imine is obtained;

[0017] 4-Styrenesulfonyl (trifluoromethylsulfonyl)imine is neutralized by potassium salt alkalization to obtain potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imine.

[0018] Preferably, potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide is added to water, followed by an initiator, and the polymerization reaction is carried out at 80-90°C for 10-30 hours under an inert atmosphere to obtain poly[potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide]; the initiator is ammonium persulfate.

[0019] Preferably, the perovskite active layer is a narrow bandgap tin-lead mixed perovskite;

[0020] The passivation layer material is at least one of EDADI, EDTA, and TBAI;

[0021] The electron transport layer is made of SnO2, TiO2, ZnO, or C. 60 At least one of PCBM;

[0022] The hole-blocking layer is made of at least one of BCP, TPI, and 8-hydroxyquinoline aluminum;

[0023] The electrode is made of at least one of Ag, Au, Cu, and Al.

[0024] The substrate is any one of ITO, FTO, and AZO.

[0025] Secondly, the present invention also provides a method for preparing the perovskite solar cell containing the polyanion buffer layer, comprising the following steps:

[0026] A neutral PEDOT layer is prepared on the substrate to obtain a hole transport layer;

[0027] A polyanion buffer layer is prepared on the hole transport layer;

[0028] A perovskite active layer is prepared on the polyanion buffer layer;

[0029] A passivation layer, an electron transport layer, a hole blocking layer, and an electrode are sequentially fabricated on the perovskite active layer.

[0030] Preferably, a DMF solution containing poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] is coated onto the surface of the hole transport layer and annealed to obtain a polyanionic buffer layer;

[0031] Preferably, a DMF solution containing poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] is spin-coated onto the surface of the hole transport layer and annealed to obtain a polyanionic buffer layer;

[0032] The spin coating speed is 3000~5000 rpm, and the spin coating time is 30~60s;

[0033] The concentration of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] in the DMF solution is 0.2~2 mg / mL; the annealing temperature is 80~120℃ and the time is 5~15 min.

[0034] Preferably, the method for preparing the hole transport layer is as follows:

[0035] A neutral PEDOT dispersion was spin-coated onto a substrate and annealed to obtain a neutral PEDOT layer.

[0036] The spin coating speed is 4000~5000 rpm, the spin coating time is 30~60s, the annealing temperature is 150~160℃, and the annealing time is 15~20min.

[0037] Thirdly, the present invention also provides an all-perovskite tandem solar cell, comprising a wide bandgap top cell and a narrow bandgap bottom cell, wherein the narrow bandgap bottom cell comprises a hole transport layer, a polyanion buffer layer, a perovskite active layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode stacked sequentially; the hole transport layer is a neutral PEDOT layer; and the polyanion buffer layer is made of potassium poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide].

[0038] The perovskite solar cell containing a polyanion buffer layer and its preparation method of the present invention have the following advantages compared with the prior art:

[0039] The perovskite solar cell containing a polyanion buffer layer of the present invention achieves the following effects by introducing a PSTFSIK polyanion buffer layer: Enhanced interface bonding: The introduction of the PSTFSIK polyanion buffer layer on the PEDOT hole transport layer enables it to form strong chemical bonds with the perovskite layer, significantly enhancing the bonding force between the hole transport layer and the perovskite buried interface. This strong interaction helps stabilize the interface and inhibit interface degradation;

[0040] Inhibit Sn 2+ Oxidation: The introduction of the PSTFSIK buffer layer effectively suppressed Sn in tin-lead perovskite. 2+ Oxidized to Sn 4+ The process reduces the defect state density, thereby reducing the number of nonradiative recombination centers;

[0041] Optimizing perovskite crystallization and stress: The PSTFSIK layer can regulate the crystallization process of tin-lead perovskite, resulting in flatter, larger-grained, and higher-quality perovskite films. Simultaneously, it effectively alleviates residual tensile strain within the perovskite film, improving film quality.

[0042] Improved energy level matching: The PSTFSIK layer can adjust the surface work function and energy level of PEDOT, making its HOMO energy level (-5.56 eV) more closely match the valence band of perovskite, reducing the energy barrier for hole transport, promoting the extraction of holes at the interface, and reducing nonradiative recombination losses at the interface.

[0043] The present invention provides a narrow bandgap (1.25 eV) perovskite solar cell based on PEDOT / PSTFSIK that achieves a photoelectric conversion efficiency of up to 24.08% and an open-circuit voltage (V). OC The voltage was significantly increased to 0.906 V. Based on this narrow bandgap bottom cell, the two-ended all-perovskite tandem solar cell achieved a photoelectric conversion efficiency of up to 29.60%. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the structure of the perovskite solar cell containing a polyanion buffer layer according to the present invention;

[0046] Figure 2 This is a schematic diagram of the structure of the all-perovskite tandem solar cell of the present invention;

[0047] Figure 3 The NMR spectra of the synthesized monomer STFSIK and polymer PSTFSIK are shown.

[0048] Figure 4 The FTIR spectra of the synthesized monomer STFSIK and polymer PSTFSIK are shown.

[0049] Figure 5 Sn 3d of fresh and aged samples from the buried surface of the perovskite active layer in perovskite solar cells after mechanical stripping in Example 1 and Comparative Example 2. 5 / 2 XPS spectrum;

[0050] Figure 6 SEM images of the buried surface of the perovskite active layer after mechanical peeling in the perovskite solar cells of Example 1 and Comparative Example 2.

[0051] Figure 7 XRD patterns of PEDOT / perovskite and PEDOT / PSTFSIK / perovskite;

[0052] Figure 8 The curves showing the open-circuit voltage and photoelectric conversion efficiency of perovskite solar cells prepared by alcohol solutions of different concentrations of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide potassium salt] in Examples 1-4 and Comparative Example 1 are shown as curves of the change of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide potassium salt] concentration.

[0053] Figure 9 The reverse and forward scan current density-voltage (JV) plots are for the perovskite solar cells prepared in Example 1 based on 1 mg / ml PSTFSIK optimization.

[0054] Figure 10 The current density-voltage (JV) plots are shown for the reverse and forward scans of the all-perovskite tandem solar cell optimized based on 1 mg / ml PSTFSIK in Example 5. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0056] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0057] This application provides a perovskite solar cell containing a polyanion buffer layer, comprising a substrate, a hole transport layer, a polyanion buffer layer, a perovskite active layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode stacked sequentially.

[0058] The hole transport layer is a neutral PEDOT layer;

[0059] The polyanion buffer layer material is poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] (PSTFSIK), and its chemical formula is shown below:

[0060]

[0061] Where n≥1, and n is a positive integer.

[0062] The perovskite solar cell of the present invention, by introducing a PSTFSIK polyanion buffer layer, achieves the following effects:

[0063] Enhanced interface bonding: The introduction of a PSTFSIK polyanion buffer layer onto the PEDOT hole transport layer enables it to form strong chemical bonds with the perovskite layer, significantly enhancing the bonding force between the hole transport layer and the perovskite buried interface. This strong interaction helps stabilize the interface and inhibit interface degradation.

[0064] Inhibit Sn 2+ Oxidation: The introduction of the PSTFSIK buffer layer effectively suppressed Sn in tin-lead perovskite. 2+ Oxidized to Sn 4+ The process reduces the defect state density, thereby reducing the number of nonradiative recombination centers;

[0065] Optimizing perovskite crystallization and stress: The PSTFSIK layer can regulate the crystallization process of tin-lead perovskite, resulting in flatter, larger-grained, and higher-quality perovskite films. Simultaneously, it effectively alleviates residual tensile strain within the perovskite film, improving film quality.

[0066] Improved energy level matching: The PSTFSIK layer can adjust the surface work function and energy level of PEDOT, making its HOMO energy level (-5.56 eV) more closely match the valence band of perovskite, reducing the energy barrier for hole transport, promoting the extraction of holes at the interface, and reducing nonradiative recombination losses at the interface.

[0067] In some embodiments, the preparation method of poly[4-styrenesulfonyl (trifluoromethylsulfonyl)imine potassium salt] includes:

[0068] Potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide was added to water, followed by an initiator, and a polymerization reaction was carried out under an inert atmosphere to obtain poly[4-styrenesulfonyl (trifluoromethylsulfonyl)imide potassium salt].

[0069] In some embodiments, the preparation method of potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imine includes:

[0070] By reacting 4-styrenesulfonyl chloride with trifluoromethylsulfonamide, 4-styrenesulfonyl (trifluoromethylsulfonyl) imine is obtained;

[0071] 4-Styrenesulfonyl (trifluoromethylsulfonyl)imine is neutralized by potassium salt alkalization to obtain potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imine.

[0072] In some embodiments, potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide is added to water, followed by an initiator, and the polymerization reaction is carried out at 80-90°C for 10-30 hours under an inert atmosphere to obtain poly[potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide]; the initiator is ammonium persulfate.

[0073] In some embodiments, the preparation method of potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imine includes:

[0074] Triethylamine, trifluoromethylsulfonamide and DMAP (4-dimethylaminopyridine) were added sequentially to acetonitrile, and the mixture was stirred until all components were dissolved to obtain a mixture.

[0075] 4-Styrenesulfonyl chloride was cooled to 0-5 °C, and then the above mixture was slowly added to 4-styrenesulfonyl chloride. After stirring and removing the solvent by rotary evaporation, a brown solid (crude product of 4-styrenesulfonyl(trifluoromethylsulfonyl)imine) was obtained.

[0076] The brown solid was dissolved in dichloromethane and washed sequentially with sodium bicarbonate aqueous solution to remove residual hydrogen chloride, organic amine catalyst, and water-soluble impurities from the reaction system. It was then washed with 1 mol / L hydrochloric acid to stabilize the product as an acidic sulfonylimide intermediate. Subsequently, potassium carbonate was added for acid-base neutralization and potassium ion replacement, completely converting the acidic sulfonylimide intermediate into potassium 4-styrenesulfonyl(trifluoromethylsulfonyl)imide (STFSIK), thus achieving monomer purification and directional salt formation.

[0077] In some embodiments, the perovskite active layer is a narrow bandgap tin-lead mixed perovskite, such as FA. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3 tin-lead mixed perovskite

[0078] In some embodiments, the passivation layer material is EDADI (ethylenediamine hydroiodide, chemical formula C2H). 10 At least one of I2N2), EDTA, and TBAI;

[0079] The electron transport layer is made of SnO2, TiO2, ZnO, or C. 60 (Fullerene), PCBM ([6,6]-phenyl-C) 61 At least one of the following: methyl butyrate;

[0080] The hole-blocking layer is made of at least one of BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), TPI, and 8-hydroxyquinoline aluminum;

[0081] The electrode material is at least one of Ag, Au, Cu, and Al.

[0082] The substrate is any one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), or aluminum-doped zinc oxide (AZO).

[0083] In some embodiments, the thickness of the substrate is 80-200 nm, the thickness of the hole transport layer is 2-20 nm, the thickness of the polyanion buffer layer is 2-20 nm, the thickness of the perovskite active layer is 500-1000 nm, the thickness of the passivation layer is 2-20 nm, the thickness of the electron transport layer is 15-50 nm, the thickness of the hole blocking layer is 10-20 nm, and the thickness of the electrode is 100-200 nm.

[0084] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned perovskite solar cell containing a polyanion buffer layer, comprising the following steps:

[0085] S1. Prepare a neutral PEDOT layer on the substrate to obtain a hole transport layer;

[0086] S2. Prepare a polyanion buffer layer on the hole transport layer;

[0087] S3. Prepare a perovskite active layer on the polyanion buffer layer;

[0088] S4. An electron transport layer and an electrode are sequentially prepared on the perovskite active layer.

[0089] In some embodiments, a DMF solution containing poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide potassium salt] is coated onto the surface of the hole transport layer and annealed to obtain a polyanion buffer layer; that is, poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide potassium salt] (PSTFSIK) is added to DMF to obtain a DMF solution containing poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide potassium salt].

[0090] In some embodiments, a DMF solution containing poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] is spin-coated onto the surface of the hole transport layer and annealed to obtain a polyanionic buffer layer;

[0091] The spin coating speed is 3000~5000 rpm, and the spin coating time is 30~60s;

[0092] The concentration of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] in the DMF solution is 0.2~2 mg / mL; the annealing temperature is 80~120℃ and the time is 5~15 min.

[0093] In some embodiments, the hole transport layer is prepared as follows:

[0094] The PEDOT dispersion was spin-coated onto a substrate and annealed to obtain a neutral PEDOT layer. The PEDOT dispersion was prepared by mixing commercially available PEDOT HTL Solar 3 solution (purchased from Xi'an Yuri Solar Energy Technology Co., Ltd.) and tris(pentafluorobenzene)borane solution (tris(pentafluorobenzene)borane was added to toluene to obtain a tris(pentafluorobenzene)borane solution with a concentration of 2.6 mg / mL) at a volume ratio of 1:1. The spin-coating speed was 4000~5000 rpm and the spin-coating time was 30~60s. The annealing temperature was 150~160℃ and the annealing time was 15~20min.

[0095] Based on the same inventive concept, the present invention also provides an all-perovskite tandem solar cell, including a wide bandgap top cell and a narrow bandgap bottom cell. The narrow bandgap bottom cell includes a hole transport layer, a polyanion buffer layer, a perovskite active layer, an electron transport layer and an electrode stacked sequentially. The hole transport layer is a neutral PEDOT layer. The polyanion buffer layer material is poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide potassium salt].

[0096] Specifically, the all-perovskite tandem solar cell of the present invention includes a wide-bandgap top cell and a narrow-bandgap bottom cell. The narrow-bandgap bottom cell is the aforementioned perovskite solar cell containing a polyanion buffer layer, but does not contain a substrate. In this scheme, to facilitate the distinction between the wide-bandgap top cell and the narrow-bandgap bottom cell, such as... Figure 1 The layers of the perovskite solar cell containing the polyanion buffer layer are named as follows: first substrate 10, first hole transport layer 11 (neutral PEDOT layer), polyanion buffer layer 12, first perovskite active layer 13 (narrow bandgap tin-lead mixed perovskite), first passivation layer 14, first electron transport layer 15, first hole blocking layer 16, and first electrode 17; wide bandgap top cell, such as... Figure 2 As shown, it includes a second substrate 20 and a second hole transport layer 21 stacked sequentially (e.g., NiO). x Nickel oxide), second passivation layer 22 (e.g., 4PADCB, [4-(7H-dibenzocarbazole-7-yl)butyl]phosphonic acid), second perovskite active layer 23 (wide-bandgap perovskite), third passivation layer 24 (e.g., PDADI, 1,3-diaminopropane dihydroiodate), second electron transport layer 25 (e.g., C 60The third electron transport layer 26 (e.g., SnO2) and the second electrode 27 (e.g., Au) are present. The entire perovskite tandem solar cell is a combination of the above-mentioned wide bandgap top cell and a perovskite solar cell without a substrate polyanion buffer layer, and the second electrode 27 is attached to the neutral PEDOT layer.

[0097] In some embodiments, the perovskite material of the wide bandgap top-mounted solar cell is FA. 0.8 Cs 0.2 PbI 1.8 Br 1.2 The band gap is 1.77 eV.

[0098] The present invention provides a narrow bandgap (1.25 eV) perovskite solar cell based on PEDOT / PSTFSIK that achieves a photoelectric conversion efficiency of up to 24.08% and an open-circuit voltage (V). OC The voltage was significantly increased to 0.906 V. Based on this, a two-terminal all-perovskite tandem solar cell constructed with a narrow bandgap bottom cell and a wide bandgap top cell achieved a photoelectric conversion efficiency of up to 29.60%.

[0099] The following detailed embodiments further illustrate the perovskite solar cell containing a polyanion buffer layer and its preparation method. This section, in conjunction with specific embodiments, further explains the content of the present invention, but should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0100] The following examples illustrate the preparation method of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] (PSTFSIK), which includes the following steps:

[0101] Synthesis of S1,4-styrenesulfonyl chloride

[0102] 2.0 mL of oxaloyl chloride (23.3 mmol) and 0.087 g of DMF (N,N-dimethylformamide, 1 mmol) were added to 40 mL of dry acetonitrile. The mixture was stirred for 5 hours to promote the formation of the Vilsmeier-Haack complex. After the solution turned yellow, 4 g of sodium 4-styrene sulfonate was added under a nitrogen atmosphere at room temperature. The mixture was stirred continuously for 24 hours, and then filtered.

[0103] The NaCl precipitate was removed to obtain a 4-styrenesulfonyl chloride solution; the synthetic route is shown below:

[0104]

[0105] Synthesis of S2,4-styrenesulfonyl (trifluoromethylsulfonyl)imine potassium (STFSIK)

[0106] Add 8.1 mL of triethylamine (58.1 mmol), 2.89 g of trifluoromethanesulfonamide (19.4 mmol), and 3.5 g of DMAP (4-dimethylaminopyridine) sequentially to 30 mL of dry acetonitrile, and stir continuously until all components are dissolved to obtain a mixture;

[0107] The 4-styrenesulfonyl chloride solution was cooled to 0 °C, and the mixture was slowly added to the solution while stirring continuously for 16 h under strong magnetic stirring. After removing the solvent by rotary evaporation, the resulting brown solid was dissolved in 50 mL of dichloromethane; the solution was washed successively with 20 mL of 4% NaHCO3 aqueous solution and 20 mL of 1 M hydrochloric acid, and then the acidity of the solution was neutralized with excess K2CO3 to obtain a solution of the potassium salt of 4-styrenesulfonyl(trifluoromethylsulfonyl)imide (STFSIK). The resulting suspension was stirred for 1 hour, filtered and dried, and recrystallized from water to obtain a pale yellow solid powder, which is STFSIK; the synthetic route is shown below:

[0108]

[0109] Synthesis of S3 and PSTFSIK polymers

[0110] 1 g of potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide was dissolved in 20 mL of deionized water and deoxygenated. 20 mg of ammonium persulfate was added, and the mixture was heated to 80 °C under a nitrogen atmosphere for 1 day. The solvent was then removed by rotary evaporation to obtain a glassy polymer. The polymer was dissolved in dimethyl sulfoxide (DMSO), and then recrystallized three times with THF to remove monomers and impurities, yielding the PSTFSIK polymer. The synthetic route is shown below:

[0111] .

[0112] Figure 3 The NMR spectra of the synthesized monomer STFSIK and polymer PSTFSIK are shown.

[0113] Figure 4 The images show the FTIR spectra of the synthesized monomer STFSIK and polymer PSTFSIK.

[0114] 1 ¹H NMR results showed that the monomer STFSIK had a vinyl hydrogen signal at δ 5.7–6.0 ppm, but this signal disappeared after polymerization, while a saturated main chain hydrogen signal appeared, proving that the addition polymerization reaction occurred.

[0115] 13 C NMR results showed that the monomer STFSIK had clear characteristic peaks of vinyl carbon and benzene ring carbon in the δ 120~140 ppm region. After polymerization, the signals of the corresponding vinyl carbon were significantly weakened or disappeared, while the signal of the benzene ring carbon was broadened due to the relaxation effect of the polymer chain segments, which confirmed the ring-opening polymerization of double bonds and the formation of polymer chains.

[0116] 19 F NMR and FTIR results showed that the polymer still contained characteristic signals of functional groups such as -CF3, -SO2, and -SNS-, indicating that the target polymer had a complete structure and no obvious side reactions occurred.

[0117] In summary, the NMR and FTIR characterization results corroborate each other, confirming the successful synthesis of the target polymer PSTFSIK.

[0118] Example 1

[0119] This embodiment provides a perovskite solar cell containing a polyanion buffer layer, comprising a substrate, a hole transport layer, a polyanion buffer layer, a perovskite active layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode stacked sequentially.

[0120] The hole transport layer is a neutral PEDOT layer;

[0121] The polyanion buffer layer material is poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] (PSTFSIK);

[0122] The substrate is indium tin oxide (ITO);

[0123] The perovskite active layer is FA 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3 tin-lead mixed perovskite;

[0124] The passivation layer material is EDADI;

[0125] The material of the electron transport layer is C 60 ;

[0126] The hole-blocking layer is made of BCP.

[0127] The electrode material is Ag;

[0128] The above-mentioned method for preparing perovskite solar cells containing polyanion buffer layers includes the following steps: S1, using ITO-coated glass (with an average ITO thickness of 100 nm) as a conductive substrate, the ITO glass is sequentially placed in distilled water and ethanol for ultrasonic cleaning, with each medium cleaning for 15 min; then dried by nitrogen gas flow, and treated with ultraviolet ozone for 15 min before use;

[0129] S2. Prepare a neutral PEDOT layer (average thickness of 10 nm) on the ITO glass surface, using the following method:

[0130] The PEDOT dispersion was spin-coated onto a substrate and annealed to obtain a neutral PEDOT layer. The PEDOT dispersion was prepared by mixing commercially available PEDOT HTL Solar 3 solution (purchased from Xi'an Sunlight Energy Technology Co., Ltd.) and tris(pentafluorobenzene)borane solution (tris(pentafluorobenzene)borane was added to toluene to obtain a tris(pentafluorobenzene)borane solution with a concentration of 2.6 mg / mL) at a volume ratio of 1:1 to obtain the PEDOT dispersion.

[0131] The spin coating speed was 4000 rpm and the spin coating time was 30s; the annealing temperature was 150℃ and the annealing time was 15min.

[0132] S3. Prepare a polyanion buffer layer (average thickness of 10 nm), the specific method is as follows:

[0133] A DMF solution containing PSTFSIK was spin-coated onto the surface of a neutral PEDOT layer and annealed to obtain a polyanionic buffer layer.

[0134] The spin coating speed was 3000 rpm and the spin coating time was 30s.

[0135] The concentration of PSTFSIK in the DMF solution was 1 mg / mL; the annealing temperature was 100℃ and the time was 5~15 min;

[0136] S4, Preparation of FA 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 The I3 perovskite active layer (average thickness 800 nm) is constructed using the following method:

[0137] The perovskite precursor solution is prepared as follows:

[0138] 0.18 mmol CsI, 1.08 mmol FAI (formamidinium hydroiodate, HC(NH2)2I), 0.54 mmol MAI (methylamine hydroiodate, CH3NH3I), 0.9 mmol PbI2, 0.9 mmol SnI2, 0.09 mmol SnF2, 0.018 mmol Pb(SCN)2, and 0.036 mmol GlyHCl (glycine hydrochloride, C2H6ClNO2) were dissolved in a 3:1 mixture of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) to obtain a perovskite precursor solution with a concentration of 1.8 M based on PbI2. The perovskite precursor solution was then spin-coated onto the surface of a polyanion buffer layer and annealed to obtain FA. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 The I3 perovskite active layer was formed by spin coating in two stages. The first stage involved spin coating at 1000 rpm for 10 seconds, while the second stage involved spin coating at 4000 rpm for 40 seconds. In the last 20 seconds (30 seconds), 350 μL of chlorobenzene was added dropwise as an antisolvent to induce rapid crystallization of the perovskite.

[0139] The annealing temperature was 100℃ and the time was 10 min;

[0140] S5. Prepare the passivation layer EDADI (average thickness of 10 nm), the specific method is as follows:

[0141] EDADI solution (1 mg / mL, obtained by dissolving EDADI in isopropanol) was spin-coated onto the surface of the perovskite active layer and annealed to obtain the passivation layer EDADI.

[0142] The spin coating speed was 4000 rpm and the spin coating time was 20s.

[0143] The annealing temperature was 100℃ and the time was 5 minutes.

[0144] S6. Electron transport layer C is sequentially deposited on the passivation layer EDADI surface using a thermal evaporation method. 60 (Average thickness is 20 nm), hole blocking layer BCP (average thickness is 7 nm) and electrode Ag (average thickness is 100 nm).

[0145] Among them, C 60 The average evaporation rate was 0.2 Å / s, the average evaporation rate of BCP was 0.1 Å / s, and the average evaporation rate of Ag was 0.5 Å / s.

[0146] Example 2

[0147] The method for preparing a perovskite solar cell containing a polyanion buffer layer provided in this embodiment is the same as in Example 1, except that the concentration of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] in the DMF solution is 0.2 mg / mL, and the thickness of the prepared polyanion buffer layer is 4 nm. All other processes are the same as in Example 1.

[0148] Example 3

[0149] The method for preparing a perovskite solar cell containing a polyanion buffer layer provided in this embodiment is the same as in Example 1, except that the concentration of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] in the DMF solution is 0.5 mg / mL, and the thickness of the prepared polyanion buffer layer is 6 nm. All other processes are the same as in Example 1.

[0150] Example 4

[0151] The method for preparing a perovskite solar cell containing a polyanion buffer layer provided in this embodiment is the same as in Example 1, except that the concentration of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] in the DMF solution is 2 mg / mL, and the thickness of the prepared polyanion buffer layer is 15 nm. All other processes are the same as in Example 1.

[0152] Example 5

[0153] This embodiment provides a method for fabricating an all-perovskite tandem solar cell, including the following steps:

[0154] S1. Using ITO-coated glass (with an average ITO thickness of 100 nm) as a conductive substrate, the ITO glass was ultrasonically cleaned in distilled water and ethanol in sequence, with each medium cleaning for 15 min; then it was dried by nitrogen gas flow and treated with ultraviolet ozone for 15 min before use.

[0155] S2, Preparation of the hole transport layer NiO x (Average thickness is 10nm), the specific method is as follows:

[0156] A nickel oxide solution (20 mg / mL, obtained by adding nickel oxide to water) was spin-coated onto the substrate surface and annealed in air to obtain a hole transport layer NiO. x ;

[0157] The spin coating speed was 4000 rpm and the spin coating time was 30s.

[0158] The annealing temperature was 120℃ and the time was 20 minutes.

[0159] S3. Prepare the passivation layer 4PADCB (average thickness 10nm), the specific method is as follows:

[0160] A 4PADCB solution (0.5 mg / mL, obtained by dissolving 4PADCB in anhydrous ethanol) was spin-coated onto the hole transport layer NiO. x The surface was annealed in air to obtain a passivation layer 4PADCB.

[0161] The spin coating speed was 3000 rpm and the spin coating time was 30s.

[0162] The annealing temperature was 100℃ and the time was 10 minutes.

[0163] S4, Preparation of FA 0.8 Cs 0.2 PbI 1.8 Br 1.2 The wide bandgap perovskite active layer (average thickness 800 nm) is constructed using the following method:

[0164] The perovskite precursor solution is prepared as follows:

[0165] 3.88 mg Pb(SCN)2, 62.35 mg CsI, 165.12 mg FAI, 264.24 mg PbBr2 and 221.28 mg PbI2 were dissolved in 1 mL of a mixed solvent of DMF and DMSO (volume ratio 3:1), and shaken for 3 h to ensure complete dissolution and mixing to form a perovskite precursor solution. The concentration of the perovskite precursor solution was 1.2 M based on PbI2.

[0166] The perovskite precursor solution was spin-coated onto the surface of the passivation layer 4PADCB and annealed to obtain FA. 0.8 Cs 0.2 PbI 1.8 Br 1.2 Wide bandgap perovskite active layer; the process involves two stages of spin coating: the first stage spin coating speed is 500 rpm and the spin coating time is 2s; the second stage spin coating speed is 4000 rpm and the spin coating time is 45s; 300μL of chlorobenzene is added dropwise at the last 20s, i.e., at 27s (as an antisolvent to induce rapid crystallization of perovskite).

[0167] The annealing temperature was 100℃ and the time was 10 min;

[0168] S5. Prepare the passivation layer PDADI (average thickness 10nm). The specific method is as follows:

[0169] The PDADI solution (1 mg / mL, obtained by dissolving PDADI in anhydrous ethanol) was spin-coated onto the FA.0.8 Cs 0.2 PbI 1.8 Br 1.2 Annealing the surface of the wide bandgap perovskite active layer yields the passivation layer PDADI.

[0170] The spin coating speed was 3000 rpm and the spin coating time was 30s.

[0171] The annealing temperature was 100℃ and the time was 5 minutes.

[0172] S6. Preparation of electron transport layer C 60 (Average thickness is 20nm), the specific method is as follows: an electron transport layer C is prepared on the surface of the passivation layer PDADI using a vapor deposition method. 60 C 60 The average evaporation rate was 0.2 Å / s;

[0173] S7. Preparation of the electron transport layer SnO2 (average thickness 20 nm): The specific method is as follows: using tetratetra(dimethylamino)tin (TDMASn) as the tin source and deionized water (H2O) as the oxygen source, the hole blocking layer surface is prepared by alternating pulse-purge cycles of tin source / water source through atomic layer deposition to obtain a SnO2 protective layer with an average thickness of 20 nm; wherein, the deposition cycle number is controlled at 200 cycles, the deposition temperature is 120℃, and the pulse / purge time is 0.3 s and 8 s, respectively;

[0174] S8. Following the method in Example 1, a neutral PEDOT layer, a polyanion buffer layer PSTFSIK, and a perovskite active layer FA are sequentially prepared on the surface of the electron transport layer SnO2. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3, passivation layer EDADI, electron transport layer C 60 Hole blocking layer BCP, electrode Ag.

[0175] Comparative Example 1

[0176] The preparation method of the perovskite solar cell provided in this comparative example is the same as that in Example 1, except that the concentration of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] in the DMF solution is 0 mg / mL, that is, it does not contain a polyanion buffer layer. All other processes are the same as in Example 1.

[0177] Comparative Example 2

[0178] This comparative example provides a PEDOT:PSS perovskite solar cell, the preparation method of which is as follows:

[0179] S1. Using ITO-coated glass (with an average ITO thickness of 100 nm) as a conductive substrate, the ITO glass was ultrasonically cleaned in distilled water and ethanol in sequence, with each medium cleaning for 15 min; then it was dried by nitrogen gas flow and treated with ultraviolet ozone for 15 min before use.

[0180] S2. Prepare a PEDOT:PSS layer (average thickness 10 nm) on the ITO glass surface, using the following method:

[0181] The PEDOT:PSS dispersion was spin-coated onto a substrate and annealed to obtain a PEDOT:PSS layer. The PEDOT:PSS dispersion was prepared by mixing commercially available PEDOT:PSS AI 4083 solution (purchased from Xi'an Sunlight Energy Technology Co., Ltd., pH 1-2) with IPA (isopropanol) at a volume ratio of 1:3 to obtain the PEDOT:PSS dispersion.

[0182] The spin coating speed was 4000 rpm and the spin coating time was 30s; the annealing temperature was 120℃ and the annealing time was 20min.

[0183] S3, Preparation of FA 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 The I3 perovskite active layer (average thickness 800 nm) is prepared using the same method as described above.

[0184] Example 1;

[0185] S5. Prepare the passivation layer EDADI (average thickness of 10 nm), the specific method is as follows:

[0186] EDADI solution (1 mg / mL, obtained by dissolving EDADI in isopropanol) was spin-coated onto the surface of the perovskite active layer and annealed to obtain the passivation layer EDADI.

[0187] The spin coating speed was 4000 rpm and the spin coating time was 20s.

[0188] The annealing temperature was 100℃ and the time was 5 minutes.

[0189] S6. Electron transport layer C is sequentially deposited on the passivation layer EDADI surface using a thermal evaporation method. 60 (Average thickness is 20 nm), hole blocking layer BCP (average thickness is 7 nm) and electrode Ag (average thickness is 100 nm).

[0190] Among them, C 60The average evaporation rate was 0.2 Å / s, the average evaporation rate of BCP was 0.1 Å / s, and the average evaporation rate of Ag was 0.5 Å / s.

[0191] Performance testing

[0192] Figure 5 The fresh ( ) buried surface of the perovskite active layer after mechanical peeling in the perovskite solar cells of Example 1 and Comparative Example 2. Figure 5 Fresh samples and aged samples (irradiated with UV lamp for 24 h) Figure 5 Sn 3d (Aged) 5 / 2 XPS spectrum; Figure 5 In this context, PEDOT:PSS / perovskite represents the perovskite solar cell in Comparative Example 2, and PEDOT / PSTFSIK / perovskite represents the perovskite solar cell in Example 1; the specific testing method involves testing the FA in the perovskite solar cell... 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 After the I3 perovskite active layer is peeled off (one side of the PEDOT:PSS layer or PSTFSIK layer is retained), the XPS spectrum of the surface is tested.

[0193] Figure 5 The image on the left shows a PEDOT:PSS / perovskite perovskite solar cell from Comparative Example 2, after aging. 2+ Almost all of them turned into Sn 4+ This is because the acidity / hydrophilicity of PEDOT:PSS leads to severe oxidation of perovskite, Sn 2+ It is consumed rapidly, resulting in a large number of defects. Figure 5 The image on the right shows the PEDOT / PSTFSIK / perovskite perovskite solar cell from Example 1, after aging (Sn). 2+ Still largely retained, Sn 4+ The fact that very few snippets are generated indicates that PSTFSIK can effectively suppress Sn. 2+ Oxidation.

[0194] Figure 6 The images are SEM images of the buried surface of the perovskite active layer after mechanical stripping in the perovskite solar cells of Example 1 and Comparative Example 1. Figure 6 In the text, PEDOT / perovskite represents the perovskite solar cell in Comparative Example 1, and PEDOT / PSTFSIK / perovskite represents the perovskite solar cell in Example 1.

[0195] from Figure 6As can be seen, the PEDOT / perovskite film in Comparative Example 1 exhibits obvious grain boundaries, cracks, and pores at the bottom, indicating severe interface defects. In contrast, the PEDOT / PSTFSIK / perovskite film of this invention has uniform and dense grains at the bottom, with no obvious defects. The results demonstrate that the PSTFSIK buffer layer can effectively optimize the nucleation and growth process of perovskite, significantly improve the film quality at the buried interface, reduce interface defects, thereby suppressing non-radiative recombination and enhancing device stability.

[0196] Figure 7 The images show the XRD patterns of the perovskite active layer prepared in Example 1, the neutral PEDOT layer prepared in Comparative Example 1, and the PEDOT:PSS layer prepared in Comparative Example 2. Here, PEDOT / perovskite represents the PEDOT layer prepared in Comparative Example 1, PEDOT / PSTFSIK / perovskite represents the perovskite active layer prepared in Example 1, and PEDOT:PSS / perovskite represents the PEDOT:PSS layer prepared in Comparative Example 2.

[0197] from Figure 7 As can be seen, compared with the control groups (Comparative Examples 1 and 2), the perovskite active layer prepared in Example 1 of this invention exhibits significantly enhanced diffraction peak intensity at the characteristic crystal planes of perovskite, with sharper peak shapes and no impurity peaks. The results indicate that PSTFSIK, as a buried interface modification layer, can effectively promote the preferred orientation growth of perovskite crystals, improve the crystallinity of the film, and increase the grain size, thereby reducing grain boundary defect density and carrier recombination, providing a foundation for achieving high photoelectric performance in the device.

[0198] Figure 8 The open-circuit voltage (V) of perovskite solar cells prepared by DMF solutions of different concentrations of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide potassium salt] in Examples 1-4 and Comparative Example 1 is measured. OC The photoelectric conversion efficiency (PCE) varies with the concentration of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt], where 0 mg / mL is Comparative Example 1. Figure 5 As can be seen, as the PSTFSIK concentration increases from 0 to 1.0 mg / mL, the PCE and V of the perovskite solar cell... oc All showed significant improvements, peaking at a concentration of 1.0 mg / mL, at which point the average PCE of the battery reached approximately 22.8%, and the average Vo was... OCThe voltage can reach approximately 0.878 V, with optimal data repeatability. When the concentration is further increased to 2.0 mg / mL, device performance degrades, indicating that excessively high concentrations introduce an additional charge transport barrier. Therefore, this invention preferably uses a PSTFSIK solution concentration of 1.0 mg / mL, which achieves the optimal balance between interface passivation and charge transport performance.

[0199] Figure 9 The current density-voltage (JV) plots are shown for the perovskite solar cells prepared in Example 1 based on 1 mg / ml PSTFSIK optimization, during reverse (scanning from high voltage to low voltage) and forward (scanning from low voltage to high voltage) scans.

[0200] Table 1 - Performance of narrow bandgap perovskite solar cells under reverse and forward scanning

[0201]

[0202] As shown in Table 1, under reverse scanning conditions, the device achieved a photoelectric conversion efficiency of up to 24.08%, with a corresponding open-circuit voltage of 0.906 V and a short-circuit current density of 32.91 mA / cm². 2 The fill factor is as high as 80.75%; under forward scanning conditions, the device efficiency is 23.61%, the open-circuit voltage is 0.900 V, and the short-circuit current density is 32.68 mA / cm². 2 The fill factor was 80.29%. The deviations of all parameters measured by forward and reverse scanning were less than 5%, and the hysteresis effect was negligible, indicating that the ion migration and interface charge trapping effects inside the device were effectively suppressed, and the charge transport and collection processes were stable.

[0203] Figure 10 The current density-voltage (JV) plots for the all-perovskite tandem solar cell optimized based on 1 mg / ml PSTFSIK in Example 5 are shown in reverse (from high voltage to low voltage) and forward (from low voltage to high voltage) scans.

[0204] The open-circuit voltage (V) of the above-mentioned all-perovskite tandem solar cell under reverse and forward scanning conditions OC ), short-circuit current density (J SC The results for fill factor (FF%) and photoelectric conversion efficiency (PCE%) are shown in Table 2 below:

[0205] Table 2 - Performance of all-perovskite tandem solar cells under reverse and forward scanning

[0206]

[0207] As shown in Table 2, under reverse scanning conditions, the device achieved a photoelectric conversion efficiency of up to 29.60%, with a corresponding open-circuit voltage of 2.154 V and a short-circuit current density of 16.71 mA / cm². 2 The fill factor is as high as 82.21%; under forward scanning conditions, the device efficiency is 29.03%, the open-circuit voltage is 2.130 V, and the short-circuit current density is 16.59 mA / cm². 2 The fill factor was 82.17%. The deviations of all parameters measured by forward and reverse scans were all less than 2%, and the hysteresis effect was negligible, indicating that the internal ion migration and interface charge trapping effects were effectively suppressed, and the charge transport and collection processes were stable. Simultaneously, the high fill factor of over 82% indicates low series resistance, high parallel resistance, good current matching between the two sub-cells, and excellent performance of the intermediate connecting layer. These results demonstrate that the PSTFSIK interface modification technology of this invention can significantly improve the performance of narrow bandgap bottom cells, thereby realizing high-efficiency, low-hysteresis, and high-stability all-perovskite tandem solar cells.

[0208] It is understood that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0209] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A perovskite solar cell containing a polyanion buffer layer, characterized in that, It includes a substrate, a hole transport layer, a polyanion buffer layer, a perovskite active layer, a passivation layer, an electron transport layer, a hole blocking layer, and electrodes stacked in sequence. The hole transport layer is a neutral PEDOT layer; The polyanion buffer layer material is poly[potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imine], and its chemical formula is shown below: ； Where n≥1, and n is a positive integer.

2. The perovskite solar cell containing a polyanion buffer layer as described in claim 1, characterized in that, The preparation method of the poly[4-styrenesulfonyl (trifluoromethylsulfonyl)imine potassium salt] includes: Potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide was added to water, followed by an initiator, and a polymerization reaction was carried out under an inert atmosphere to obtain poly[4-styrenesulfonyl (trifluoromethylsulfonyl)imide potassium salt].

3. The perovskite solar cell containing a polyanion buffer layer as described in claim 2, characterized in that, The preparation method of the potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imine includes: By reacting 4-styrenesulfonyl chloride with trifluoromethylsulfonamide, 4-styrenesulfonyl (trifluoromethylsulfonyl) imine is obtained; 4-Styrenesulfonyl (trifluoromethylsulfonyl)imine is neutralized by potassium salt alkalization to obtain potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imine.

4. The perovskite solar cell containing a polyanion buffer layer as described in claim 2, characterized in that, Potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide was added to water, followed by an initiator. The polymerization reaction was carried out at 80-90°C for 10-30 hours under an inert atmosphere to obtain poly[potassium 4-styrenesulfonyl (trifluoromethylsulfonyl)imide]; the initiator was ammonium persulfate.

5. The perovskite solar cell containing a polyanion buffer layer as described in claim 1, characterized in that, The perovskite active layer is a narrow bandgap tin-lead mixed perovskite; The passivation layer material is at least one of EDADI, EDTA, and TBAI; The electron transport layer is made of SnO2, TiO2, ZnO, or C. 60 At least one of PCBM; The hole-blocking layer is made of at least one of BCP, TPI, and 8-hydroxyquinoline aluminum; The electrode is made of at least one of Ag, Au, Cu, and Al; The substrate is any one of ITO, FTO, and AZO.

6. A method for preparing a perovskite solar cell containing a polyanion buffer layer as described in any one of claims 1 to 5, characterized in that, Includes the following steps: A neutral PEDOT layer is prepared on the substrate to obtain a hole transport layer; A polyanion buffer layer is prepared on the hole transport layer; A perovskite active layer is prepared on the polyanion buffer layer; A passivation layer, an electron transport layer, a hole blocking layer, and an electrode are sequentially fabricated on the perovskite active layer.

7. The method for preparing a perovskite solar cell containing a polyanion buffer layer as described in claim 6, characterized in that, A DMF solution containing poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] was coated onto the surface of the hole transport layer and annealed to obtain a polyanionic buffer layer.

8. The method for preparing a perovskite solar cell containing a polyanion buffer layer as described in claim 7, characterized in that, A DMF solution containing poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] was spin-coated onto the surface of the hole transport layer and annealed to obtain a polyanionic buffer layer; The spin coating speed is 3000~5000 rpm, and the spin coating time is 30~60s; The concentration of poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imine potassium salt] in the DMF solution is 0.2~2 mg / mL; the annealing temperature is 80~120℃ and the time is 5~15 min.

9. The method for preparing a perovskite solar cell containing a polyanion buffer layer as described in claim 6, characterized in that, The method for preparing the hole transport layer is as follows: The PEDOT dispersion was spin-coated onto the substrate and annealed to obtain a neutral PEDOT layer. The spin coating speed is 4000~5000 rpm, the spin coating time is 30~60s, the annealing temperature is 150~160℃, and the annealing time is 15~20min.

10. A fully perovskite tandem solar cell, characterized in that, The battery includes a wide bandgap top cell and a narrow bandgap bottom cell. The narrow bandgap bottom cell includes a hole transport layer, a polyanion buffer layer, a perovskite active layer, a passivation layer, an electron transport layer, a hole blocking layer, and an electrode, which are stacked sequentially. The hole transport layer is a neutral PEDOT layer. The polyanion buffer layer is made of potassium poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide].

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