Perovskite solar cell based on a neutral buffer and a method of manufacturing the same

Abstract

The application relates to a perovskite solar cell based on a neutral buffer and a preparation method thereof, the perovskite solar cell is from bottom to top a transparent conductive substrate layer, a perovskite light-absorbing layer, an electron transport layer, an interface modification layer and an electrode layer, wherein the perovskite light-absorbing layer contains a neutral buffer; the structural general formula of the neutral buffer is X.Y, wherein X is a self-assembled monomolecular organic acid, and Y is a reducing organic amine. The neutral buffer is used for regulating perovskite crystallization and passivating a buried bottom interface, a chelate is formed through hydrogen bond action to inhibit solvent evaporation and delay the crystallization rate, a preparation window period is widened, and large-area perovskite film uniformization preparation is facilitated. High solubility of the neutral buffer in a precursor solution can induce spontaneous aggregation of the neutral buffer at a bottom interface of the perovskite film, improve a hole concentration, reduce a defect density, and greatly improve a carrier lifetime of the perovskite film, thereby providing an important reference for industrialization of the perovskite solar cell.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and particularly relates to a perovskite solar cell based on a neutral buffer and its preparation method. Background Technology

[0002] In recent years, organolead halide perovskite materials have become a research focus, demonstrating application potential in fields such as light-emitting diodes (LEDs) and lasers. Their breakthroughs in photovoltaic technology are particularly noteworthy, with certified photoelectric conversion efficiencies reaching 27%. Lead halide perovskite materials not only possess highly efficient light absorption capabilities but also generate free carriers and achieve charge transport. One of their core advantages lies in the ability to prepare high-quality polycrystalline thin films using various solution deposition processes. Although device efficiency can be significantly improved by finely controlling the perovskite composition, deposition process, and solvent mixing ratio, existing research largely focuses on empirical parameter optimization, lacking systematic studies on the precursor solution chemistry and its impact on the crystallization process.

[0003] Introducing self-assembled monomolecular organic acid additives into the perovskite precursor solution is one of the effective methods to achieve hole-transport-free perovskite solar cells. The introduction of acidic additives lowers the pH value of the perovskite precursor solution, significantly altering the chemical environment, accelerating the aging of the perovskite precursor solution, reducing the crystallinity and carrier transport performance of the perovskite film, and severely affecting the stability and consistency of the perovskite solar cell fabrication process, thus hindering the industrialization of perovskite solar cells. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a perovskite solar cell based on a neutral buffer and its preparation method. By introducing a neutral buffer material into the perovskite precursor solution, the acid-base balance of the precursor solution is achieved without altering its chemical environment, thus inhibiting chemical degradation. Furthermore, the interaction between the neutral buffer and the perovskite grain surface facilitates the interaction between acid radicals and uncoordinated Pb at grain boundaries. 2+ Strong bonds are formed between them, reducing Pb 2+ The surrounding electron density decreases, leading to a decrease in the electron donor density of the perovskite, which in turn increases the hole concentration in the perovskite and effectively improves hole conduction in the bottom perovskite.

[0005] According to a first aspect of the embodiments of this application, a perovskite solar cell based on a neutral buffer is provided, wherein the perovskite solar cell comprises, from bottom to top, a transparent conductive substrate layer, a perovskite light-absorbing layer, an electron transport layer, an interface modification layer, and an electrode layer, wherein the perovskite light-absorbing layer contains a neutral buffer.

[0006] The neutral buffer has the general structural formula X·Y, where X is a self-assembled monomolecular organic acid, including one or more of carbazole-based organic acids, triphenylamine-based organic acids, and acridine-based organic acids, with the corresponding chemical structural formulas as follows:

[0007]

[0008] Where R1 represents one or more combinations of hydrogen, halogen (F, Cl, Br, I), methyl, methoxy, ethyl, ethoxy, trifluoromethyl, n-propyl, n-propoxy, isopropyl, isopropoxy, n-butyl, n-butoxy, isobutyl, isobutoxy, sec-butyl, sec-butoxy, tert-butyl, tert-butoxy, phenyl, benzyl, phenethyl, phenoxy, phenethyl, benzyloxy, and phenethoxy; R2 represents one or more combinations of hydrogen, halogen (F, Cl, Br, I), methyl, methoxy, ethyl, ethoxy, trifluoromethyl, n-propyl, n-propoxy, isopropyl, isopropoxy, and n-propyl. One or more combinations of butyl, n-butoxy, isobutyl, isobutoxy, sec-butyl, sec-butoxy, tert-butyl, tert-butoxy, phenyl, benzyl, phenethyl, phenoxy, phenethyl, benzyloxy, and phenethoxy; R3 is one or more combinations of methylene, methine, phenylene, benzylene, phenethylene, styryl, and vinylene; R4 is one of carboxylic acid, phosphonic acid, sulfonic acid, boric acid, cyanocarboxylic acid, cyanophosphonic acid, cyanosulfonic acid, and cyanoboronic acid; X is one of ether, thioether, methylene, and methine; n is 1, 2, 3, 4, 5…;

[0009] Y is a reducing organic amine, including organic amine compounds containing one or more combined groups from the following groups: hydrazine, acylhydrazine, n C=C double bonds (n=2,3,4…), phenolic hydroxyl, aldehyde, mercapto, and ferrocene.

[0010] Furthermore, the transparent conductive substrate layer is made of FTO glass, ITO glass, ITO / PET, ITO / PEN, or ITO / PI.

[0011] Furthermore, the perovskite light-absorbing layer has the general structural formula ABX3 and a thickness of 100–2000 nm, where A represents Cs. + MA + or FA + B is Pb 2+ Sn 2+ Or Ge 2+ X is I - ,Br - or Cl - .

[0012] Furthermore, the electron transport layer is a fullerene or its derivative, with a thickness of 1–100 nm.

[0013] Furthermore, the interface modification layer is made of copper bath, tin oxide, zinc oxide, yttrium oxide, cerium oxide, titanium oxide or niobium oxide, and has a thickness of 1 to 100 nm.

[0014] Furthermore, the electrode layer is Cu, Ag, Au, Mo, ITO, IZO or AZO, with a thickness of 10 to 10000 nm.

[0015] According to a second aspect of the embodiments of this application, a method for fabricating a perovskite solar cell based on a neutral buffer as described in the first aspect is provided, comprising:

[0016] (1) Synthesize neutral buffers;

[0017] (2) Dissolve the perovskite powder in an organic solvent, stir and clarify to form a perovskite precursor solution, add a neutral buffer, dissolve completely to obtain a perovskite precursor solution containing a neutral buffer, coat or print the perovskite precursor solution containing a neutral buffer on a clean transparent conductive substrate and heat treat it to obtain a perovskite light-absorbing layer.

[0018] (3) An electron transport layer, an interface modification layer and an electrode layer are sequentially deposited on the perovskite light-absorbing layer to obtain a perovskite solar cell based on a neutral buffer.

[0019] Further, in step (2), the organic solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, 2-methoxyethanol, and acetonitrile, preferably 2-methoxyethanol and N-methylpyrrolidone (volume ratio of 9:1), the concentration of the perovskite precursor solution is 0.1-3 mol / L, preferably 1.25 mol / L, the concentration of the neutral buffer in the perovskite precursor solution containing the neutral buffer is 0.001-50 mg / mL, preferably 5 mg / mL, the heat treatment temperature is 30-300℃, and the time is 5-120 minutes, preferably 110℃ for 30 minutes.

[0020] Further, in step (3), the electron transport layer is deposited by vapor deposition, the interface modification layer is deposited by vapor deposition, sputtering, reactive plasma deposition, chemical vapor deposition, coating, or printing, preferably reactive plasma deposition, and the electrode layer is deposited by vapor deposition, sputtering, chemical vapor deposition, coating, or printing, preferably sputtering deposition.

[0021] The technical solution provided in this application may include the following beneficial effects:

[0022] 1. This invention employs a neutral buffer to improve the long-term stability of the perovskite precursor solution. The reducing organic amine effectively neutralizes the acidity or alkalinity of the perovskite precursor solution while simultaneously removing elemental iodine generated in the perovskite active layer, inhibiting the self-accelerated degradation process of the perovskite, thereby significantly improving the long-term operational stability of the perovskite battery. Furthermore, the lone pair electrons on the sulfur atoms in this buffer can interact with the unsaturated Pb atoms at the bottom of the perovskite. 2+ Electron supply leads to the formation of coordination bonds, and the strong interaction enhances the bonding between the molecules and the perovskite surface, which is helpful for the preparation of large-area, high-quality perovskite thin films.

[0023] 2. The interaction between the neutral buffer and the perovskite used in this invention can optimize the interface energy level arrangement, improve the charge transport capability of the device, and form a high built-in electric field at the buried interface of the perovskite, which helps the separation of electrons and holes, enhances the separation and transport efficiency of charge carriers, and thus improves the photoelectric performance of the perovskite battery.

[0024] 3. The organic acid anchoring groups in the neutral buffer used in this invention can effectively passivate perovskite surface defects, alleviate interfacial charge recombination, and promote in-plane growth of perovskite grains, thereby improving the photothermal stability of perovskite solar cells.

[0025] 4. The perovskite solar cells regulated by the neutral buffer of this invention have advantages such as high photoelectric conversion efficiency, good long-term working stability, and high reproducibility of fabrication.

[0026] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0028] Figure 1 This is a schematic diagram of the perovskite solar cell structure based on oxalohydrazide·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate of the present invention.

[0029] Figure 2 The graph shows the change in absorbance of the perovskite precursor solution containing oxalohydrazide·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate of the present invention when placed in air for different times.

[0030] Figure 3 This is a graph showing the relationship between the efficiency of the perovskite solar cell containing oxalohydrazide·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate of the present invention and the time the perovskite precursor solution is left in air. Detailed Implementation

[0031] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0032] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0033] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0034] The perovskite solar cell provided by this invention comprises, from bottom to top, a transparent conductive substrate layer, a perovskite light-absorbing layer, an electron transport layer, an interface modification layer, and an electrode layer, wherein the perovskite light-absorbing layer contains a neutral buffer. This invention utilizes a neutral buffer to achieve crystallization regulation of the perovskite and passivation of the buried interface. The buffer can form hydrogen bonds with perovskite organic cations and solvents, and form chelates with metal halides in the perovskite precursor, inhibiting solvent evaporation during perovskite crystallization and slowing down the crystallization rate of the perovskite. This significantly extends the preparation window time for perovskite film formation, facilitating the homogenization of large-area perovskite film preparation. The high solubility of the neutral buffer in the precursor solution can induce its spontaneous aggregation at the bottom interface of the perovskite film, leading to an increase in the perovskite hole concentration at the buried interface, reducing the defect density at the bottom interface, and significantly improving the carrier lifetime of the perovskite film.

[0035] To address the above problems, the present invention provides the following specific embodiments.

[0036] Example:

[0037] like Figure 1 As shown, a method for fabricating a perovskite solar cell based on a neutral buffer includes the following steps:

[0038] (1) Weigh 118.1 mg (1 mmol) of oxalohydrazine into 10 mL of anhydrous ethanol. Weigh 493.15 mg (1 mmol) of 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonic acid into 10 mL of anhydrous ethanol. Slowly add the 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonic acid ethanol solution to the continuously stirred oxalohydrazine ethanol solution. Maintain the reaction time as follows: The reaction temperature was maintained at 0 degrees Celsius. After the addition was completed, the mixture was stirred for 40 minutes. The crude product of oxalohydrazide 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonate was obtained by rotary evaporation. The crude product was washed four times with ethyl acetate and diethyl ether to obtain pure oxalohydrazide 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonate (446 mg, yield approximately 73%). The product was then dried under vacuum for 12 hours for later use.

[0039] (2) The FTO glass was ultrasonically cleaned sequentially with glass cleaning agent, ultrapure water and alcohol. After cleaning, it was dried to obtain a clean FTO glass substrate.

[0040] (3) First, weigh CsI, MAI, FAI, and PbI2 powder (molar ratio 0.05:0.15:0.8:1.08) and dissolve them in a mixed solvent of 2-methoxyethanol and N-methylpyrrolidone (volume ratio 9:1). After stirring and clarifying, a 1.25 mol / L perovskite precursor solution is obtained. Then, weigh 5 mg of oxalohydrazide·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate and add it to 1 mL of the perovskite precursor solution. After complete dissolution by stirring in the precursor solution, a perovskite precursor solution containing oxalohydrazide 4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate was obtained. The perovskite precursor solution containing oxalohydrazide 4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate was slit-coated on a clean FTO glass substrate. The coated perovskite wet film was heat-treated at 110℃ for 30 min to obtain a perovskite light-absorbing layer with a thickness of 500 nm.

[0041] (4) A 30 nm thick C60 electron transport layer, a 20 nm thick tin oxide interface modification layer, and a 500 nm thick IZO electrode layer are sequentially deposited on the perovskite light-absorbing layer to obtain a perovskite solar cell based on oxalylhydrazine·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate neutral buffer.

[0042] Comparative Example 1:

[0043] A perovskite solar cell without a neutral buffer and its fabrication method, comprising the following steps:

[0044] (1) The FTO glass was ultrasonically cleaned sequentially with glass cleaning agent, ultrapure water and alcohol, and dried after cleaning to obtain a clean FTO glass substrate.

[0045] (2) First, weigh CsI, MAI, FAI, and PbI2 (molar ratio of 0.05:0.15:0.8:1.08) powder and dissolve them in a mixed solvent of 2-methoxyethanol and N-methylpyrrolidone (volume ratio of 9:1). After stirring and clarifying, a 1.25 mol / L perovskite precursor solution is obtained. The perovskite precursor solution is slit-coated on a clean FTO glass substrate. The coated perovskite wet film is heat-treated at 110℃ for 30 min to obtain a perovskite light-absorbing layer with a thickness of 500 nm.

[0046] (3) A 30 nm thick C60 electron transport layer, a 20 nm thick tin oxide interface modification layer, and a 500 nm thick IZO electrode layer are sequentially deposited on the perovskite light-absorbing layer to obtain a perovskite solar cell without neutral buffer.

[0047] Comparative Example 2:

[0048] A perovskite solar cell based on self-assembled single-molecule organic acid and its preparation method, comprising the following steps:

[0049] (1) The FTO glass was ultrasonically cleaned sequentially with glass cleaning agent, ultrapure water and alcohol, and dried after cleaning to obtain a clean FTO glass substrate.

[0050] (2) First, weigh CsI, MAI, FAI, and PbI2 powder (molar ratio 0.05:0.15:0.8:1.08) and dissolve them in a mixed solvent of 2-methoxyethanol and N-methylpyrrolidone (volume ratio 9:1). After stirring and clarifying, a 1.25 mol / L perovskite precursor solution is obtained. Then, weigh 5 mg of the perovskite precursor solution. 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonic acid was added to 1 mL of perovskite precursor solution and stirred until completely dissolved to obtain a perovskite precursor solution containing 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonic acid. The perovskite precursor solution containing 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonic acid was slit-coated onto a clean FTO glass substrate. The coated perovskite wet film was heat-treated at 110 °C for 30 min to obtain a perovskite light-absorbing layer with a thickness of 500 nm.

[0051] (3) A 30 nm thick C60 electron transport layer, a 20 nm thick tin oxide interface modification layer, and a 500 nm thick IZO electrode layer are sequentially deposited on the perovskite light-absorbing layer to obtain a perovskite solar cell based on 4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonic acid.

[0052] Comparative Example 3:

[0053] A perovskite solar cell based on neutral buffer interface modification and its fabrication method, comprising the following steps:

[0054] (1) Weigh 118.1 mg (1 mmol) of oxalohydrazine into 10 mL of anhydrous ethanol. Weigh 493.15 mg (1 mmol) of 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonic acid into 10 mL of anhydrous ethanol. Slowly add the 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonic acid ethanol solution to the continuously stirred oxalohydrazine ethanol solution. Maintain the reaction time as follows: The reaction temperature was maintained at 0 degrees Celsius. After the addition was completed, the mixture was stirred for 40 minutes. The crude product of oxalohydrazide 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonate was obtained by rotary evaporation. The crude product was washed four times with ethyl acetate and diethyl ether to obtain pure oxalohydrazide 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonate (446 mg, yield approximately 73%). The product was then dried under vacuum for 12 hours for later use.

[0055] (2) The FTO glass was ultrasonically cleaned sequentially with glass cleaning agent, ultrapure water and alcohol. After cleaning, it was dried to obtain a clean FTO glass substrate. A 2 mg / mL oxalohydrazide·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate ethanol solution was coated on the clean FTO glass substrate. After coating, it was heat-treated at 100℃ for 5 min to obtain a 3 nm oxalohydrazide·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate layer.

[0056] (3) Weigh CsI, MAI, FAI, and PbI2 (molar ratio of 0.05:0.15:0.8:1.08) powder and dissolve them in a mixed solvent of 2-methoxyethanol and N-methylpyrrolidone (volume ratio of 9:1). After stirring and clarifying, a 1.25 mol / L perovskite precursor solution is obtained. The perovskite precursor solution is slit-coated on a substrate covered with an oxalylhydrazine·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate layer. The coated perovskite wet film is heat-treated at 110℃ for 30 min to obtain a perovskite light-absorbing layer with a thickness of 500 nm.

[0057] (4) A 30 nm thick C60 electron transport layer, a 20 nm thick tin oxide interface modification layer, and a 500 nm thick IZO electrode layer are sequentially deposited on the perovskite light-absorbing layer to obtain a perovskite solar cell based on the interface modification of oxalylhydrazine·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate.

[0058] As shown in Table 1, the perovskite solar cell prepared using oxalohydrazine·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate as a neutral buffer has a photoelectric conversion efficiency of 26.21%, and the efficiency of the cell only decreases by 3.7% after 1000 hours of maximum power point tracking. The device efficiency and stability are far superior to those of other comparative devices, indicating that the addition of oxalohydrazine·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate to the perovskite precursor solution can improve the crystal quality of the perovskite film, optimize the band structure of the buried interface, eliminate the charge transport barrier, and improve the charge transport rate, thus achieving a perovskite cell that balances high efficiency and high stability.

[0059] Table 1. Performance parameters of products from examples and comparative examples

[0060]

[0061] Perovskite precursor solutions containing oxalohydrazide·4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonate and 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonic acid were placed in air for different times. The absorption edge wavelengths of the two perovskite precursor solutions after different placement times were measured, and solar cells were fabricated based on the two perovskite precursor solutions placed for different times. Figure 2 As shown, compared to the perovskite precursor solution containing 4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonic acid, the perovskite precursor solution containing oxalohydrazide·4-(3,7-dibromo-10H-benzothiazin-10-yl)butylphosphonate showed almost no increase in iodine concentration after being exposed to air for 30 days. This indicates that the addition of oxalohydrazide·5-phenyl-2,4-pentadienoate can significantly improve the long-term stability of the perovskite precursor solution and greatly inhibit its aging degradation. Figure 3 As shown, the performance of the perovskite solar cells prepared based on perovskite precursor solutions containing oxalohydrazide·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate placed for different times remained basically unchanged. This also confirms that oxalohydrazide·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate can effectively maintain the acid-base balance of the perovskite precursor solution and eliminate the performance reduction of perovskite cells caused by precursor solution deterioration.

[0062] Therefore, combining Figures 2-3 As shown, the devices prepared using perovskite precursor solutions with oxalohydrazide·4-(3,7-dibromo-10H-benzothiazine-10-yl)butylphosphonate as neutral buffer exhibit high performance consistency, significantly extend the service life of the perovskite precursor solution, and significantly improve the photoelectric conversion efficiency and stability of perovskite solar cells, which is conducive to the mass production of large-area perovskite cells.

[0063] The above description is merely a preferred experimental example of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A perovskite solar cell based on a neutral buffer, characterized in that, The perovskite solar cell consists of, from bottom to top, a transparent conductive substrate layer, a perovskite light-absorbing layer, an electron transport layer, an interface modification layer, and an electrode layer, wherein the perovskite light-absorbing layer contains a neutral buffer. The general structural formula of the neutral buffer is X·Y, where X is a self-assembled monomolecular organic acid, including one or more of carbazole-based organic acids, triphenylamine-based organic acids, and acridine-based organic acids, and Y is a reducing organic amine, including organic amine compounds containing one or more combined groups of hydrazine, acylhydrazine, n C=C double bonds, phenolic hydroxyl, aldehyde, mercapto, and ferrocene.

2. The perovskite solar cell based on a neutral buffer as described in claim 1, characterized in that, The transparent conductive substrate layer is made of FTO glass, ITO glass, ITO / PET, ITO / PEN or ITO / PI.

3. The perovskite solar cell based on a neutral buffer as described in claim 1, characterized in that, The perovskite light-absorbing layer has the general structural formula ABX3 and a thickness of 100–2000 nm, where A is Cs. + MA + or FA + B is Pb 2+ Sn 2+ Or Ge 2+ X is I - ,Br - or Cl - .

4. The perovskite solar cell based on a neutral buffer as described in claim 1, characterized in that, The electron transport layer is fullerene and its derivatives, with a thickness of 1–100 nm.

5. The perovskite solar cell based on a neutral buffer as described in claim 1, characterized in that, The interface modification layer is made of copper bath, tin oxide, zinc oxide, yttrium oxide, cerium oxide, titanium oxide or niobium oxide, and has a thickness of 1 to 100 nm.

6. The perovskite solar cell based on a neutral buffer as described in claim 1, characterized in that, The electrode layer is made of Cu, Ag, Au, Mo, ITO, IZO or AZO, with a thickness of 10 to 10,000 nm.

7. The method for preparing a perovskite solar cell based on a neutral buffer as described in any one of claims 1-6, characterized in that, include: (1) Synthesize neutral buffers; (2) Dissolve the perovskite powder in an organic solvent, stir and clarify to form a perovskite precursor solution, add a neutral buffer, dissolve completely to obtain a perovskite precursor solution containing a neutral buffer, coat or print the perovskite precursor solution containing a neutral buffer on a clean transparent conductive substrate and heat treat it to obtain a perovskite light-absorbing layer. (3) An electron transport layer, an interface modification layer and an electrode layer are sequentially deposited on the perovskite light-absorbing layer to obtain a perovskite solar cell based on a neutral buffer.

8. The method for preparing a perovskite solar cell based on a neutral buffer as described in claim 7, characterized in that, In step (2), the organic solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, 2-methoxyethanol, and acetonitrile; the concentration of the perovskite precursor solution is 0.1–3 mol / L; the concentration of the neutral buffer in the perovskite precursor solution containing the neutral buffer is 0.001–50 mg / mL; the heat treatment temperature is 30–300 °C; and the time is 5–120 minutes.

9. The method for preparing a perovskite solar cell based on a neutral buffer as described in claim 7, characterized in that, In step (3), the electron transport layer is deposited by vapor deposition, the interface modification layer is deposited by vapor deposition, sputtering, reactive plasma deposition, chemical vapor deposition, coating, or printing, and the electrode layer is deposited by vapor deposition, sputtering, chemical vapor deposition, coating, or printing.

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