A natural pigment perovskite cathode buffer layer material and its application

Abstract

The present invention relates to a natural pigment perovskite cathode buffer layer material and an application thereof, wherein the natural pigment perovskite cathode buffer layer material comprises anthracene. The present invention uses natural pigments as perovskite cathode buffer layer materials, thereby improving the defects on the surface of the electron transport layer of the perovskite battery, optimizing the morphology of the electron transport layer, and improving the open circuit voltage and fill factor of the perovskite battery. At the same time, the addition of natural pigments can reduce the work function of the metal electrode and increase the short-circuit current of the perovskite battery. Furthermore, natural pigments can improve the hydrophobicity of the surface of the perovskite battery, thereby improving its stability. The natural pigment perovskite cathode buffer layer material of the present invention has low cost, wide sources, is environmentally friendly, and is conducive to achieving low-cost optimization of perovskite batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite batteries, in particular to a perovskite cathode buffer layer material and an application thereof, and in particular to a natural pigment perovskite cathode buffer layer material and an application thereof. Background Art

[0002] At present, perovskite batteries generally have problems with battery interface contact, which easily leads to loss of interface energy. Inserting a cathode buffer layer between the electron transport layer and the metal electrode can effectively improve the above problems. Therefore, research on the perovskite cathode buffer layer is very necessary.

[0003] In perovskite cells, the main function of the cathode buffer layer is to adjust the energy level arrangement, improve the electron extraction efficiency, reduce the interface recombination loss, and block the migration of moisture and ions, thereby improving the efficiency and stability of the battery. Therefore, in order to improve the performance of perovskite cells, researchers are exploring new cathode buffer layer materials, such as self-assembled monolayers (SAMs) or ionic layers of potassium fluoride (KF), to improve the interface properties and further improve the overall performance of the battery.

[0004] However, the development of cathode buffer layer materials is susceptible to conditions such as stability, interface compatibility, charge transport, material selection and preparation process, cost and scalability. Regarding stability, cathode buffer layer materials may degrade in an environment with long-term illumination, resulting in a decrease in battery performance, especially in a high temperature and high humidity environment. The battery performance decrease is particularly obvious. Regarding interface compatibility, incompatible interfaces may cause electron recombination, reduce the charge collection efficiency, and thus affect the overall performance of the battery. Regarding charge transport, many buffer layer materials cannot achieve the ideal electron transport efficiency. Regarding material selection and preparation process, the synthesis process of the material needs to be precisely controlled to ensure that it has good electron transport properties and stability. Regarding cost and scalability, some efficient buffer layer materials may be expensive, or their preparation process is not suitable for large-scale production.

[0005] CN107805254A discloses a porphyrin small molecule perovskite cathode buffer layer material and its preparation method and application. One layer of the buffer layer material described in the invention can replace the C 60 and BCP two-layer interface, and can also improve device performance; and the porphyrin small molecule perovskite cathode buffer layer material of the invention has water-alcohol solubility and can be solution-spin coated, greatly reducing device costs. However, the porphyrin small molecule has a complex structure, a complex synthesis process, and a high raw material cost.

[0006] The existing technology has defects such as high cost and complex synthesis process of perovskite cathode buffer layer materials. Therefore, providing a buffer layer material with a wide source, low cost and effective performance of perovskite cells has become an urgent problem to be solved. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a natural pigment perovskite cathode buffer layer material and its application. The present invention uses natural pigments as perovskite cathode buffer layer materials, which can improve the defects on the surface of the electron transport layer of the perovskite battery, optimize the morphology of the electron transport layer, and improve the open circuit voltage and filling factor of the perovskite battery. At the same time, the addition of natural pigments can reduce the work function of the metal electrode and increase the short-circuit current of the perovskite battery. Further, natural pigments can improve the hydrophobicity of the surface of the perovskite battery, thereby improving its stability. The natural pigment perovskite cathode buffer layer material of the present invention has low cost, wide sources, is environmentally friendly, and is conducive to achieving low-cost optimization of perovskite batteries.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a natural pigment perovskite cathode buffer layer material, wherein the natural pigment perovskite cathode buffer layer material has a structural formula of Wherein, R1-R8 include any one of hydrogen, hydroxyl, carboxyl or methyl.

[0010] The present invention uses natural pigments as perovskite cathode buffer layer materials, which can improve the defects on the surface of the electron transport layer of the perovskite battery, optimize the morphology of the electron transport layer, and improve the open circuit voltage and fill factor of the perovskite battery. At the same time, the addition of natural pigments can reduce the work function of the metal electrode and increase the short-circuit current of the perovskite battery. Further, natural pigments can improve the hydrophobicity of the surface of the perovskite battery, thereby improving its stability. The natural pigment perovskite cathode buffer layer material of the present invention has low cost, wide sources, is environmentally friendly, and is conducive to achieving low-cost optimization of perovskite batteries.

[0011] Preferably, said R1 comprises hydrogen or hydroxy.

[0012] Preferably, said R2 comprises hydrogen or hydroxy.

[0013] Preferably, said R3 comprises hydrogen or hydroxy.

[0014] Preferably, said R4 comprises hydrogen or hydroxy.

[0015] Preferably, said R5 comprises hydrogen or hydroxy.

[0016] Preferably, said R6 comprises hydrogen or hydroxy.

[0017] Preferably, said R7 comprises hydrogen, hydroxyl or carboxyl.

[0018] Preferably, said R8 comprises hydrogen or methyl.

[0019] Preferably, in the structure of the natural pigment perovskite cathode buffer layer material, the number of hydroxyl groups is 3-5, for example, 3, 4 or 5.

[0020] Hydroxyl (-OH) can act as an electron donor or acceptor, affecting the availability and transport capacity of electrons in the material. Specifically, the present invention can control the potential distribution of the molecule and improve the performance of the cathode buffer layer by adjusting the number of hydroxyl groups in the natural pigment perovskite cathode buffer layer material.

[0021] Preferably, the natural pigment perovskite cathode buffer layer material includes 3,5,6,8-tetrahydroxy-1-methyl-9,10-dioxo-2-anthracenecarboxylic acid methyl ester, whose structural formula is Abbreviated as TmDAc.

[0022] In a second aspect, the present invention provides a method for preparing a cathode buffer layer of a perovskite battery, the preparation method comprising the following steps: dissolving the natural pigment perovskite cathode buffer layer material described in the first aspect in an organic solvent to obtain a mixed solution, and then spin coating the mixed solution on the electron transport layer of the perovskite battery to obtain the perovskite battery cathode buffer layer.

[0023] Preferably, the organic solvent comprises isopropanol and / or ethanol.

[0024] Preferably, the concentration of the mixed solution is 0.1 mg / mL-0.9 mg / mL, for example, it can be 0.1 mg / mL, 0.3 mg / mL, 0.5 mg / mL, 0.7 mg / mL or 0.9 mg / mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] The cathode buffer layer of the present invention can improve the extraction efficiency and transmission efficiency of electrons and improve the performance of the perovskite battery. Within the preferred concentration range of the mixed solution, the thickness of the cathode buffer layer of the prepared perovskite battery is uniform and moderate. Furthermore, the perovskite battery corresponding to the cathode buffer layer of the present invention has excellent stability, and performance parameters such as short-circuit current, open-circuit voltage and fill factor are further improved.

[0026] Preferably, the spin coating rotation speed is 400r / min-600r / min, for example, it can be 400r / min, 450r / min, 500r / min, 550r / min or 600r / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] In a third aspect, the present invention provides a perovskite battery cathode buffer layer, wherein the perovskite cathode buffer layer is prepared by the preparation method described in the second aspect.

[0028] In a fourth aspect, the present invention provides a perovskite cell, wherein the perovskite cell comprises the perovskite cell cathode buffer layer described in the third aspect.

[0029] Preferably, the perovskite cell comprises a transparent conductive layer, a hole transport layer, a perovskite layer, an electron transport layer and a metal electrode layer which are stacked in sequence; and the perovskite cell cathode buffer layer described in the third aspect is arranged between the electron transport layer and the metal electrode layer.

[0030] In the perovskite cells corresponding to certain application examples, the material of the transparent conductive layer includes any one of FTO, ITO, AZO, ATO, IGO or BZO, or a combination of at least two of them. Typical but non-limiting combinations include a combination of FTO and ITO, or a combination of FTO, ITO and AZO.

[0031] Among them, FTO refers to fluorine-doped tin oxide, ITO refers to indium-doped tin oxide, AZO refers to aluminum-doped zinc oxide, ATO refers to aluminum-doped tin oxide, IGO refers to indium-doped gallium oxide, and BZO refers to boron-doped zinc oxide.

[0032] In the perovskite cells corresponding to certain application examples, the material of the hole transport layer includes any one or a combination of at least two of nickel oxide, vanadium oxide, aluminum oxide, molybdenum oxide, copper sulfide, cuprous thiocyanate, copper oxide, cuprous oxide, cobalt oxide, 1,1-bis-4-4-methylphenylaminophenyl)cyclohexylamine (TAPC), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), PEDOT (poly(3,4-ethylenedioxythiophene)), Poly-TPD (poly(4-butylphenyldiphenylamine)) or 2,2,7,7-tetrakis(N,N-p-methoxyanilino)-9,9-spirobifluorene (Spiro-MeOTAD). Typical but non-limiting combinations include a combination of nickel oxide and vanadium oxide, a combination of cuprous oxide and cobalt oxide, a combination of aluminum oxide and PTAA, a combination of PEDOT and Poly-TPD, or a combination of PTAA, Poly-TPD and Spiro-MeOTAD.

[0033] In the perovskite battery corresponding to some application examples, the material of the perovskite layer is ABX3 type perovskite, wherein A is Cs + , K + 、Ru + 、CH3NH3 + 、C(NH2)3 + 、CH(NH2)2+ Any one or a combination of at least two of the following, typical but non-limiting combinations include Cs + With K + Combination of CH3NH3 + 、C(NH2)3 + With CH(NH2)2 + Combination of, B is Pb 2+ and / or Sn 2+ , X is Br - ,I - or Cl - Any one or a combination of at least two of the following, typical but non-limiting combinations include Br - with I - Combination of I - With Cl - A combination of Br - ,I - With Cl - combination.

[0034] In the perovskite cells corresponding to certain application examples, the material of the metal electrode layer includes any one of Cu, Ag, Au, Al, Cr, Ni or Ti, or a combination of at least two of them. Typical but non-limiting combinations include a combination of Cu and Ag, a combination of Cu and Au, a combination of Au, Ag and Al, a combination of Ag, Au, Al and Cr, or a combination of Cu, Ag, Au, Al, Cr, Ni and Ti.

[0035] Compared with the prior art, the present invention has at least the following beneficial effects:

[0036] (1) The present invention uses natural pigments as perovskite cathode buffer layer materials, thereby improving the surface defects of the electron transport layer of the perovskite battery, optimizing the morphology of the electron transport layer, and improving the open circuit voltage and fill factor of the perovskite battery.

[0037] (2) The addition of the natural pigment of the present invention can reduce the work function of the metal electrode and increase the short-circuit current of the perovskite battery.

[0038] (3) In the present invention, natural pigments can improve the hydrophobicity of the surface of the perovskite battery, thereby improving its stability.

[0039] (4) The natural pigment perovskite cathode buffer layer material of the present invention is low-cost, widely available, and environmentally friendly, which is conducive to achieving low-cost optimization of perovskite batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a schematic structural diagram of a perovskite battery corresponding to Application Example 1-1 of the present invention;

[0041] Figure 2 1 is the JV curve of the perovskite battery corresponding to Application Example 1-1, Application Example 4 to Application Example 7 and Comparative Application Example 3 of the present invention;

[0042] Figure 3 UPS test curves of the perovskite battery and the reference battery corresponding to Application Example 1-1 of the present invention;

[0043] Figure 4 are stability curves of the perovskite battery and the reference battery corresponding to Application Example 1-1 of the present invention and Comparative Application Example 3;

[0044] Among them, 1 is a substrate, 2 is a PTAA layer, 3 is a perovskite layer, 4 is a PCBM layer, 5 is a cathode buffer layer, and 6 is a silver electrode. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0046] Example 1

[0047] This embodiment provides a natural pigment perovskite cathode buffer layer material, the structural formula of the natural pigment perovskite cathode buffer layer material is

[0048] Example 2

[0049] This embodiment provides a natural pigment perovskite cathode buffer layer material, the structural formula of the natural pigment perovskite cathode buffer layer material is

[0050] Example 3

[0051] This embodiment provides a natural pigment perovskite cathode buffer layer material, the structural formula of the natural pigment perovskite cathode buffer layer material is

[0052] Example 4

[0053] The only difference between this embodiment and embodiment 1 is that, except that the substituents of R2 and R5 are replaced by hydroxyl groups, the rest are the same as embodiment 1.

[0054] Example 5

[0055] The only difference between this embodiment and embodiment 1 is that, except that the substituents of R3 and R4 are replaced by hydrogen, the rest are the same as embodiment 1.

[0056] Comparative Example 1

[0057] This comparative example provides a perovskite cathode buffer layer material, the structural formula of the perovskite cathode buffer layer material is

[0058] Comparative Example 2

[0059] This comparative example provides a natural pigment perovskite cathode buffer layer material, wherein the natural pigment perovskite cathode buffer layer material is chlorophyll.

[0060] Application Example 1-1

[0061] This application example provides a method for preparing a cathode buffer layer of a perovskite battery, the preparation method comprising the following steps:

[0062] The natural pigment perovskite cathode buffer layer material described in Example 1 was dissolved in isopropanol to obtain a mixed solution, and then the mixed solution was spin-coated on the electron transport layer of the perovskite battery to obtain the perovskite battery cathode buffer layer. The concentration of the mixed solution was 0.5 mg / mL, and the rotation speed of the spin coating was 500 r / min.

[0063] Figure 1 is a schematic diagram of the structure of the perovskite battery corresponding to Application Example 1-1 of the present invention, Figure 1 It can be seen that the perovskite battery corresponding to this application example has an additional cathode buffer layer structure.

[0064] Figure 3 It is the UPS test curve of the perovskite battery and the reference battery corresponding to the application example 1-1 of the present invention. It can be seen from the figure that the addition of the natural pigment perovskite cathode buffer layer material of the present invention reduces the work function of the metal electrode, which is beneficial to the generation of more electrons that can be collected at the interface between the metal electrode and the PCBM, and is beneficial to improving the carrier transmission efficiency.

[0065] Application Example 1-2

[0066] This application example provides a method for preparing a cathode buffer layer of a perovskite battery, the preparation method comprising the following steps:

[0067] The natural pigment perovskite cathode buffer layer material described in Example 1 was dissolved in ethanol to obtain a mixed solution, and then the mixed solution was spin-coated on the electron transport layer of the perovskite battery to obtain the perovskite battery cathode buffer layer. The concentration of the mixed solution was 0.9 mg / mL, and the rotation speed of the spin coating was 600 r / min.

[0068] Application Examples 1-3

[0069] This application example provides a method for preparing a cathode buffer layer of a perovskite battery, the preparation method comprising the following steps:

[0070] The natural pigment perovskite cathode buffer layer material described in Example 1 was dissolved in isopropanol to obtain a mixed solution, and then the mixed solution was spin-coated on the electron transport layer of the perovskite battery to obtain the perovskite battery cathode buffer layer. The concentration of the mixed solution was 0.1 mg / mL, and the spin-coating speed was 400 r / min.

[0071] Application Example 2

[0072] The only difference between this application example and application example 1-1 is that, except for using the natural pigment perovskite cathode buffer layer material described in Example 2, the rest is the same as application example 1-1.

[0073] Application Example 3

[0074] The only difference between this application example and application example 1-1 is that, except for using the natural pigment perovskite cathode buffer layer material described in Example 3, the rest is the same as application example 1-1.

[0075] Application Example 4

[0076] The only difference between this application example and application example 1-1 is that, except that the concentration of the mixed solution is 0.1 mg / mL, the rest is the same as application example 1-1.

[0077] Application Example 5

[0078] The only difference between this application example and application example 1-1 is that, except that the concentration of the mixed solution is 0.3 mg / mL, the rest is the same as application example 1-1.

[0079] Application Example 6

[0080] The only difference between this application example and application example 1-1 is that, except that the concentration of the mixed solution is 0.7 mg / mL, the rest is the same as application example 1-1.

[0081] Application Example 7

[0082] The only difference between this application example and application example 1-1 is that, except that the concentration of the mixed solution is 0.9 mg / mL, the rest is the same as application example 1-1.

[0083] Application Example 8

[0084] The difference between this application example and application example 1-1 is that, except for using the natural pigment perovskite cathode buffer layer material described in Example 4, the rest is the same as application example 1-1.

[0085] Application Example 9

[0086] The difference between this application example and application example 1-1 is that, except for using the natural pigment perovskite cathode buffer layer material described in Example 5, the rest is the same as application example 1-1.

[0087] Comparative application example 1

[0088] The only difference between this comparative application example and application example 1-1 is that, except for using the natural pigment perovskite cathode buffer layer material described in comparative example 1, the rest is the same as application example 1-1.

[0089] Comparative Application Example 2

[0090] The only difference between this comparative application example and application example 1-1 is that, except for using the natural pigment perovskite cathode buffer layer material described in comparative example 2, the rest is the same as application example 1-1.

[0091] Comparative Application Example 3

[0092] The only difference between this comparative application example and application example 1-1 is that, except for spin coating of isopropyl alcohol, the rest is the same as application example 1-1.

[0093] Figure 2 It is the JV curve of the perovskite solar cell corresponding to Application Example 1-1, Application Example 4-Application Example 7 and Comparative Application Example 3 of the present invention. It can be seen from the figure that, compared with the reference cell, the photovoltaic performance of the corresponding perovskite cell is improved by adding the natural pigment perovskite cathode buffer layer material.

[0094] Figure 4 It is the stability curve of the perovskite battery and the reference battery corresponding to Application Example 1-1 of the present invention and Comparative Application Example 3. It can be seen from the figure that after adding the cathode interface buffer layer of the present invention between the electron transport layer and the metal electrode, the stability of the perovskite battery is also improved. In an air environment at 25°C, the efficiency of the perovskite battery corresponding to Comparative Application Example 3 of the present invention drops to 48% of the original efficiency after 15 days, while the efficiency of the perovskite battery corresponding to Application Example 1-1 of the present invention can be maintained at 80% after 15 days.

[0095] Test Method

[0096] The cathode buffer layers of the perovskite cells prepared in Application Examples 1-1 to Application Examples 9 and Comparative Application Examples 1 to Comparative Application Examples 3 are assembled into perovskite cells. The preparation method of the test perovskite cell includes the following steps:

[0097] The substrate was ultrasonically cleaned in deionized water, ethanol and isopropanol for 10 minutes each, and then treated with oxygen plasma on its surface to further improve its work function and adsorption effect. Then, a PTAA solution with a concentration of 3.5 mg / mL (the solvent is chlorobenzene) was added to the substrate and rotated at a speed of 4000 r / min for 30 seconds. Then, it was immediately placed in an environment of 120°C and heated until the temperature was stable. Then, it was heated for 10 minutes, cooled, and after the substrate cooled to room temperature, it was transferred to a glove box filled with nitrogen and the perovskite absorption layer was prepared by blade scraping. The specific steps of this part are the same as those of PTAA spin coating. After the blade coating is completed, the newly coated liquid precursor film is immediately transferred to a vacuum chamber, and the vacuum is pumped to 1000 Pa within 15 seconds, and maintained at this pressure for 90 seconds. The film is then taken out of the vacuum chamber and annealed at 100°C in the glove box for 10 minutes to crystallize the film to obtain a perovskite film. On the wide bandgap perovskite film, PCBM (the solution is chlorobenzene, and the solution concentration is 20 mg / mL) is spin-coated at a speed of 2000 r / min, and then the cathode buffer layer of the perovskite battery is prepared according to the methods of Application Examples 1 to Application Examples 9 and Comparative Application Examples 1 to Comparative Application Examples 3. Then the substrate is moved into the evaporation equipment and The 120nm thick silver electrode was deposited at a speed of 1.500 nm, and the effective surface area was 0.09cm 2 of perovskite batteries.

[0098] The perovskite batteries corresponding to Application Examples 1-1 to Application Examples 9 and Comparative Application Examples 1 to Comparative Application Examples 3 were subjected to UPS tests and stability tests, and corresponding JV curves were drawn. At the same time, the energy conversion efficiency of the perovskite batteries was recorded in Table 1.

[0099] Table 1

[0100]

[0101]

[0102] The test results show that:

[0103] (1) It can be seen from Application Example 1-1 to Application Example 9 and Comparative Application Example 1 to Comparative Application Example 3 that the present invention can improve the defects on the surface of the electron transport layer of the perovskite battery, optimize the morphology of the electron transport layer, and improve the open circuit voltage and fill factor of the perovskite battery by using natural pigments as perovskite cathode buffer layer materials. At the same time, the addition of natural pigments can reduce the work function of the metal electrode and increase the short-circuit current of the perovskite battery. Further, natural pigments can improve the hydrophobicity of the surface of the perovskite battery, thereby improving its stability. The natural pigment perovskite cathode buffer layer material of the present invention is low in cost, widely available, and environmentally friendly, which is conducive to achieving low-cost optimization of perovskite batteries.

[0104] (2) It can be seen from Application Examples 1-1 and Application Examples 4 to 7 that the present invention can further improve the energy conversion efficiency of the perovskite battery by further regulating the concentration of the spin coating solution of the natural pigment perovskite cathode buffer layer material.

[0105] (3) It can be seen from Application Example 1-1 and Application Example 8-Application Example 9 that the present invention can further improve the energy conversion efficiency of the perovskite battery by further regulating the number of hydroxyl groups in the structure of the natural pigment perovskite cathode buffer layer material.

[0106] (4) It can be seen from Application Example 1-1 and Comparative Application Example 1-Comparative Application Example 2 that the present invention can reduce the cost of materials and improve the energy conversion efficiency of perovskite batteries by selecting natural pigments with specific structures as perovskite cathode buffer layer materials.

[0107] In summary, the present invention uses natural pigments as perovskite cathode buffer layer materials, which can improve the defects on the surface of the electron transport layer of the perovskite battery, optimize the morphology of the electron transport layer, and improve the open circuit voltage and fill factor of the perovskite battery. At the same time, the addition of natural pigments can reduce the work function of the metal electrode and increase the short-circuit current of the perovskite battery. Further, natural pigments can improve the hydrophobicity of the surface of the perovskite battery, thereby improving its stability. The natural pigment perovskite cathode buffer layer material of the present invention has low cost, wide sources, is environmentally friendly, and is conducive to achieving low-cost optimization of perovskite batteries.

[0108] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A natural pigment perovskite cathode buffer layer material, characterized in that: The structural formula of the natural pigment perovskite cathode buffer layer material is Wherein, R1-R8 include any one of hydrogen, hydroxyl, carboxyl or methyl.

2. The natural pigment perovskite cathode buffer layer material according to claim 1, characterized in that: In the structure of the natural pigment perovskite cathode buffer layer material, the number of hydroxyl groups is 3-5.

3. The natural pigment perovskite cathode buffer layer material according to claim 1 or 2, characterized in that: The natural pigment perovskite cathode buffer layer material includes 3,5,6,8-tetrahydroxy-1-methyl-9,10-dioxo-2-anthracenecarboxylic acid methyl ester, and its structural formula is 4. A method for preparing a cathode buffer layer of a perovskite battery, characterized in that: The preparation method comprises the following steps: The natural pigment perovskite cathode buffer layer material according to any one of claims 1 to 3 is dissolved in an organic solvent to obtain a mixed solution, and then the mixed solution is spin-coated on the electron transport layer of the perovskite battery to obtain the perovskite battery cathode buffer layer.

5. The preparation method according to claim 4, characterized in that: The organic solvent includes isopropanol and / or ethanol.

6. The preparation method according to claim 4 or 5, characterized in that: The concentration of the mixed solution is 0.1 mg / mL-0.9 mg / mL.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The rotation speed of the spin coating is 400r / min-600r / min.

8. A cathode buffer layer for a perovskite battery, characterized in that: The perovskite cathode buffer layer is prepared by the preparation method according to any one of claims 4 to 7.

9. A perovskite battery, characterized in that: The perovskite cell comprises the perovskite cell cathode buffer layer according to claim 8.

10. The perovskite battery according to claim 9, characterized in that: The perovskite cell comprises a transparent conductive layer, a hole transport layer, a perovskite layer, an electron transport layer and a metal electrode layer which are stacked in sequence; the perovskite cell cathode buffer layer according to claim 9 is arranged between the electron transport layer and the metal electrode layer.

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