A trans-perovskite solar cell and a preparation method thereof

Abstract

A kind of transverse perovskite solar cell, including transparent conductive layer, hole transport layer, perovskite absorption layer, electron transport layer and back electrode layer arranged in sequence;Back electrode layer is the composite structure of transparent conductive oxide layer and active metal layer;Electron transport layer is fullerene electron transport layer;Transverse perovskite solar cell further includes buffer layer, buffer layer is located between electron transport layer and back electrode layer, and buffer layer is molybdenum-doped indium oxide layer.Using molybdenum-doped indium oxide as buffer layer, compared with traditional tungsten-doped indium oxide, in the top electron collection interface of transverse perovskite solar cell, better energy level matching, more superior low-temperature electrical performance, stronger interface stability and wider process window are realized.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cells, and in particular to the field of an inverted perovskite solar cell. Background Technology

[0002] Organic-inorganic halide perovskite semiconductor materials possess advantages such as high light absorption coefficient, high carrier mobility, tunable bandgap, and bipolar carrier transport. Their relatively low defect density and excellent defect tolerance make them highly promising in the photovoltaic field. In 2009, Japanese scientists Kojima et al. first achieved a photoelectric conversion efficiency of 3.8% using CH3NH3PbI3 as a light-absorbing layer material. In 2017, the research group of You Jingbi at the Chinese Academy of Sciences achieved a photoelectric conversion efficiency of 21.1% for a nip-type planar perovskite solar cell using solution-processed SnO2 as the electron transport layer. Currently, the highest photoelectric conversion efficiency of single-junction perovskite solar cells has reached 26.2%, approaching the highest efficiency of crystalline silicon solar cells, and possesses theoretical advantages such as low cost and ease of fabrication, making it one of the most active research directions in the materials and energy fields. However, as competitors to traditional commercial solar photovoltaic products, perovskite solar cells must also match their stability. The long-term stability of perovskite solar cells remains a crucial challenge and technology for the commercialization of emerging photovoltaics. To further improve efficiency and stability, optimizing charge extraction, suppressing nonradiative recombination at the interface, and reducing contact resistance are the core challenges. In perovskite solar cells, fullerene derivatives (such as C60) are often used as electron transport layers due to their excellent electron transport properties. However, there are significant technical bottlenecks in fabricating high-performance, low-damage transparent top electrodes on these layers to achieve efficient charge collection. 1. Energy level mismatch problem: There is a large potential barrier between the work function (usually 4.5-5.2 eV) of commonly used transparent conductive oxides (such as indium tin oxide ITO, tungsten-doped indium oxide IWO, etc.) and the lowest unoccupied molecular orbital energy level of C60 (about -4.0 eV), which makes electron extraction difficult, resulting in high contact resistance and severely limiting the fill factor and power conversion efficiency of the device. 2. Interface recombination loss: At the back electrode interface, holes from the perovskite layer may be transported in the reverse direction to the electron transport layer and recombine with the collected electrons, resulting in open-circuit voltage loss.

[0003] In existing technologies, high-performance transparent conductive oxides such as IWO are often used as buffer layers. While these provide good lateral conductivity, their inherent work function makes it difficult to effectively modulate the band structure of the C60 interface, resulting in insufficient contribution to suppressing hole recombination and constructing ohmic contacts. Therefore, there is an urgent need to develop a novel interface buffer layer material and structure that can fundamentally solve the aforementioned interface energy level mismatch and recombination problems, and be compatible with low-temperature, low-damage electrode fabrication processes, thereby promoting the practical application of efficient and stable perovskite optoelectronic devices. Summary of the Invention

[0004] The main technical problem addressed by this invention is the significant potential barrier between the work function of commonly used transparent conductive oxides and the lowest unoccupied molecular orbital energy level of C60. This barrier leads to difficulties in electron extraction, high contact resistance, and severely limits the fill factor and power conversion efficiency of the device. At the back electrode interface, holes from the perovskite layer may propagate in the reverse direction to the electron transport layer and recombine with collected electrons, resulting in open-circuit voltage loss. In existing technologies, high-performance transparent conductive oxides such as IWO are often used as buffer layers. Although they provide good lateral conductivity, their inherent work function is insufficient to effectively modulate the band structure of the C60 interface, thus contributing insufficiently to suppressing hole recombination and constructing ohmic contacts.

[0005] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is to provide an inverted perovskite solar cell, comprising a transparent conductive layer, a hole transport layer, a perovskite absorber layer, an electron transport layer and a back electrode layer arranged sequentially. The back electrode layer is a composite structure of a transparent conductive oxide layer and an active metal layer; The electron transport layer is a fullerene-type electron transport layer; The inverted perovskite solar cell further includes a buffer layer located between the electron transport layer and the back electrode layer, and the buffer layer is a molybdenum-doped indium oxide layer.

[0006] Furthermore, the molybdenum doping amount in the molybdenum-doped indium oxide layer is 1%at-5%at.

[0007] Furthermore, the molybdenum doping content in the molybdenum-doped indium oxide layer is 3% at.

[0008] Furthermore, the thickness of the buffer layer is 5 nm-15 nm.

[0009] Furthermore, the thickness of the buffer layer is 15 nm.

[0010] Furthermore, the buffer layer undergoes plasma treatment.

[0011] Furthermore, the plasma processing power is 100W-200W.

[0012] This invention also provides a method for preparing an inverted perovskite solar cell, comprising the following steps: A transparent conductive layer is provided, on which a hole transport layer, a perovskite absorption layer, and an electron transport layer are sequentially formed. A buffer layer is formed on the electron transport layer. The buffer layer is a molybdenum-doped indium oxide layer, and the buffer layer is subjected to plasma treatment. A transparent conductive layer and an active metal layer are sequentially formed on the buffer layer as the back electrode.

[0013] Furthermore, the buffer layer is formed by reactive plasma deposition, and the power of the plasma treatment of the buffer layer is 100W-200W.

[0014] Furthermore, the thickness of the molybdenum-doped indium oxide layer is 5-15 nm; the molybdenum doping amount of the molybdenum-doped indium oxide layer is 1%at-5%at.

[0015] The beneficial effects of this invention are as follows: By adding a buffer layer (i.e., an IMO layer) between the electron transport layer and the back electrode layer, a more perfect energy level alignment can be formed with the LUMO energy level of mainstream fullerene-based ETLs (such as C60), thereby establishing a lower-loss ohmic contact, significantly reducing the electron extraction barrier, improving the device fill factor, and simultaneously optimizing the work function. This promotes efficient electron extraction while more effectively suppressing back-interface recombination, which is beneficial for obtaining a higher open-circuit voltage. Furthermore, the IMO material can achieve high conductivity and high mobility after mild annealing or plasma treatment at temperatures below 150°C, or even at room temperature.

[0016] Compared to traditional tungsten-doped indium oxide, this method achieves better energy level matching, superior low-temperature electrical performance, stronger interface stability, and a wider process window at the top electron collection interface of inverted perovskite solar cells. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an inverted perovskite solar cell; Figure 2 This is a flowchart of the fabrication process for inverted perovskite solar cells; Detailed Implementation

[0018] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0019] In existing inverted perovskite solar cells, fullerene derivatives (such as C60) are often used as electron transport layers due to their excellent electron transport properties. However, significant technical bottlenecks remain in fabricating high-performance, low-damage transparent top electrodes on these layers to achieve efficient charge collection. 1. Energy level mismatch problem: There is a large potential barrier between the work function (usually 4.5-5.2 eV) of commonly used transparent conductive oxides (such as indium tin oxide ITO, tungsten-doped indium oxide IWO, etc.) and the lowest unoccupied molecular orbital energy level of C60 (about -4.0 eV), which makes electron extraction difficult, resulting in high contact resistance and severely limiting the fill factor and power conversion efficiency of the device. 2. Interface recombination loss: At the back electrode interface, holes from the perovskite layer may propagate in the reverse direction to the electron transport layer, recombine with collected electrons, and cause open-circuit voltage loss. In existing technologies, high-performance transparent conductive oxides such as IWO are often used as buffer layers. Although they can provide good lateral conductivity, their inherent work function is difficult to effectively modulate the band structure of the C60 interface, and their contribution to suppressing hole recombination and constructing ohmic contacts is insufficient.

[0020] This invention provides an inverted perovskite solar cell, comprising a transparent conductive layer, a hole transport layer, a perovskite absorber layer, an electron transport layer, and a back electrode layer. A buffer layer, which is an IMO (indium molybdenum doped) layer, is introduced into the electron transport layer and the back electrode layer. This buffer layer enables better energy level matching, superior low-temperature electrical performance, stronger interface stability, and a wider process window at the top electron collection interface of the inverted perovskite solar cell.

[0021] The fabrication method of this inverted perovskite solar cell includes the following steps: Step 1: The FTO conductive glass is ultrasonically cleaned with glass cleaner and deionized water in sequence, and then thoroughly dried in an oven at 100℃. After that, P1 laser line scribing is performed. The cleaning is repeated twice. The FTO conductive glass is then treated with ultraviolet-ozone for 30 minutes. After that, it is put into the magnetron sputtering equipment to be coated. Step 2: In a vacuum below 1*10 -3 At Pa, a high-purity argon and argon-oxygen mixture was set and a radio frequency power supply was used to perform magnetron sputtering of a nickel oxide target on FTO glass to form a hole transport layer. Step 3: Apply an appropriate amount of SAMs solution to the hole transport layer surface for lower interface passivation coating. Remove excess solvent using nitrogen gas, anneal at 70℃ for 2 minutes on a heating stage, and then anneal at 100℃-150℃ for 10 minutes. Then, coat the surface with Cs using a perovskite precursor solution. 0.05 FA 0 .95PbI3 was annealed at 70°C for 2 minutes on a heating stage after removing excess solvent with nitrogen gas, and then annealed at 100°C-150°C for 40 minutes to form a perovskite absorber layer.

[0022] Step 4: Vacuum evaporation is used to deposit the perovskite active layer on the surface at a vacuum degree of less than 10. -4 Under Pa conditions, C60 is deposited at a deposition rate of 0.1-0.5 A / s to form an electron transport layer; Step 5: Apply reactive plasma deposition (RPD) to the electron transport layer surface at a vacuum level of less than 1*10⁻⁶. - 3 Under Pa conditions, a molybdenum-doped indium oxide (IMO) thin film is deposited. After depositing the IMO thin film, plasma treatment is performed. The workpiece is placed in a vacuum chamber and fixed, and the chamber is evacuated to a high vacuum using a vacuum pump. Specific gases O2 and Ar are introduced into the vacuum chamber as process gases. A high-frequency voltage is applied to induce glow discharge in the gas within the vacuum chamber, forming plasma. The substrate is then enveloped with plasma, causing a reaction that lasts for 3 minutes. After the plasma treatment is completed, P2 laser scribing is performed.

[0023] Step Six: Apply radio frequency magnetron sputtering to the surface of the buffer layer under a vacuum level of less than 1*10. - 3 Under Pa conditions, transparent conductive oxide ITO and active metal Cu are deposited respectively. After the above electrode layers are prepared, P3 / P4 scribing is performed in sequence to obtain the perovskite solar cell.

[0024] In step two of the preparation method of the inverted perovskite solar cell, the hole transport layer is made of materials including but not limited to vanadium oxide, tungsten oxide, magnesium oxide, cuprous thiocyanate (CuSCN), cuprous iodide (CuI), copper oxide (CuO), cuprous oxide (Cu2O), nickel oxide (NiO), vanadium pentoxide (V2O5), etc. The thickness of the hole transport thin film layer in this invention is 10-25 nm. In step three, the coating speed is 10-15 mm / s, and the chemical formula of the perovskite absorber layer is ABX3, where A includes any one or a combination of at least two of formamidinium ions, methylamine ions, or cesium ions; B includes lead ions; and X is a halide ion. For example, it can be FAPbI3, MAPbI3, or FAXCs. 1-x PbI3, FaxCs1-xPbIyBr 3-y 、FACsMAPbI y Br 3-y Or CsPbI3, etc., where the value of x ranges from 0.05 to 0.2, the value of y ranges from 0 to 3, and the thickness of the perovskite thin film absorption layer is 300 nm - 500 nm; In step four, the thickness of the electron transport layer ranges from 5 nm to 50 nm. In step five, the molybdenum doping ratio of molybdenum-doped indium oxide is between 1%at and 10%at, and the thickness of the buffer layer is between 5 and 15 nm. In the plasma treatment used for the buffer layer, the plasma treatment power is between 100W and 200W. In step six, the active metal electrode layer material includes, but is not limited to, any one or a combination of at least two of Cu, Mo, Cr, Ag, or Au electrodes. The optimal thickness range for the metal back electrode is 15 nm to 100 nm, and deposition methods include evaporation and magnetron sputtering. Transparent conductive oxides include indium tin oxide (ITO), zinc aluminum oxide (AZO), indium tungsten oxide (IWO), indium tungsten zinc oxide (IWZO), indium gallium zinc oxide (IGZO), and indium zinc oxide (IZO), and deposition methods include reactive plasma deposition (RPD) and magnetron sputtering, with an optimal thickness range of 15 nm to 200 nm.

[0025] Example 1: Example 1 includes a transparent conductive layer, a hole transport layer, a perovskite absorber layer, an electron transport layer, a buffer layer, and a back electrode layer, which are sequentially stacked. In this example, the buffer layer is a molybdenum-doped indium oxide (IMO) layer, wherein the molybdenum doping amount is 3% at. The specific preparation method is as follows. Step 1: The FTO conductive glass is ultrasonically cleaned with glass cleaner and deionized water in sequence, and then thoroughly dried in an oven at 100℃. After that, P1 laser line scribing is performed. The cleaning is repeated twice. The FTO conductive glass is then treated with ultraviolet-ozone for 30 minutes. After that, it is put into the magnetron sputtering equipment to be coated. Step 2: When the vacuum is below 1*10-3Pa, set the flow rate of high-purity argon and argon-oxygen mixture and use an RF power supply to perform magnetron sputtering of a nickel oxide target on FTO glass to obtain a hole transport layer with a thickness of 15nm. Step 3: Apply an appropriate amount of SAMs solution to the hole transport layer surface for lower interface passivation coating. Remove excess solvent using nitrogen gas. Anneal at 70℃ for 2 minutes on a heating stage, then anneal at 100℃-150℃ for 10 minutes. Finally, coat the surface with Cs using a perovskite precursor solution. 0.05 FA 0 .95 PbI3 (concentration of 1.1M, thickness of 500nm) was purged with nitrogen to remove excess solvent, annealed at 70℃ for 2 min on a heating stage, and then annealed at 100℃-150℃ for 40 min to form a perovskite absorber layer. Step 4: Vacuum evaporation is used to deposit the perovskite absorber layer on the surface at a vacuum level of less than 10. -4Under Pa conditions, C60 with a thickness of 12 nm was deposited by thermal evaporation at a deposition rate of 0.1–0.5 A / s. Step 5: Apply reactive plasma deposition to the electron transport layer surface at a vacuum level of less than 1*10⁻⁶. - 3 Under Pa conditions, a 10 nm molybdenum-doped indium oxide thin film with a molybdenum doping ratio of 3%at was deposited, and then P2 laser scribing was performed after plasma treatment with a power of 100W. Step Six: Apply radio frequency magnetron sputtering to the surface of the buffer layer under a vacuum level of less than 1*10. - 3 Under Pa conditions, 80 nm transparent conductive oxide ITO and 80 nm active metal Cu were deposited respectively. After the above back electrode layers were prepared, P3 / P4 scribing was performed in sequence to obtain Example 1.

[0026] Example 2: The difference between this embodiment and Embodiment 1 is that the molybdenum doping ratio of the molybdenum-doped indium oxide is 5%at, while the rest of the preparation methods and parameters remain the same as in Embodiment 1.

[0027] Example 3: The difference between this embodiment and Embodiment 1 is that the molybdenum doping ratio of the molybdenum-doped indium oxide is 1%at, while the rest of the preparation methods and parameters remain the same as in Embodiment 1.

[0028] Example 4: The difference between this embodiment and Embodiment 1 is that the molybdenum doping ratio of the molybdenum-doped indium oxide is 10%at, while the rest of the preparation methods and parameters remain the same as in Embodiment 1.

[0029] Example 5: The difference between this embodiment and Embodiment 1 is that the thickness of the molybdenum-doped indium oxide buffer layer is 5 nm, while the rest of the preparation methods and parameters are the same as in Embodiment 1.

[0030] Example 6: The difference between this embodiment and Embodiment 1 is that the thickness of the molybdenum-doped indium oxide buffer layer is 15 nm, while the rest of the preparation methods and parameters are the same as in Embodiment 1.

[0031] Example 7: The difference between this embodiment and Embodiment 1 is that the plasma power is 200W, while the rest of the preparation methods and parameters remain the same as in Embodiment 1.

[0032] Example 8: The difference between this embodiment and Embodiment 1 is that the plasma power is 50W, while the rest of the preparation methods and parameters remain the same as in Embodiment 1.

[0033] Comparative Example 1: The preparation method for this comparative example is as follows: Step 1: The FTO conductive glass is ultrasonically cleaned with glass cleaner and deionized water in sequence, and then thoroughly dried in an oven at 100℃. This process is repeated 3 times to obtain the FTO conductive glass layer. Before nickel oxide coating, the FTO conductive glass is subjected to ultraviolet-ozone treatment for 30 minutes. After the treatment, it is placed in a magnetron sputtering equipment to be coated. Step 2: In a vacuum below 1*10 -3 At Pa, a high-purity argon and argon-oxygen mixture was set and magnetron sputtering was performed on FTO glass using an RF power supply to obtain a hole transport layer with a thickness of 15 nm. Step 3: Apply an appropriate amount of SAM solution to the hole transport layer surface for lower interface passivation coating. Remove excess solvent using nitrogen gas. Anneal at 70℃ for 2 minutes on a heating stage, then anneal at 100℃-150℃ for 10 minutes. Finally, coat the surface with a perovskite precursor solution to form Cs. 0.05 FA 0 .95 PbI3 (concentration 1.1M, thickness 500nm) was used to remove excess solvent by blowing away nitrogen gas. It was first annealed at 70℃ for 2 min on a heating stage, and then annealed at 100℃-150℃ for 40 min to form a perovskite absorber layer.

[0034] Step 4: A C60 layer with a thickness of 12 nm is deposited on the surface of the perovskite absorber layer using a vacuum evaporation method under a vacuum degree of less than 10⁻⁴ Pa. The deposition rate of C60 is 0.1-0.5 A / s. Step 5: Apply reactive plasma deposition to the electron transport layer surface at a vacuum level of less than 1*10⁻⁶. - 3 A 13 nm tungsten-doped indium oxide thin film was deposited under Pa conditions and then subjected to P2 laser scribing.

[0035] Step Six: Radio frequency magnetron sputtering is used on the surface of the electron transport layer at a vacuum level less than 1*10⁻⁶. - 3 Under Pa conditions, 80 nm transparent conductive oxide ITO and 80 nm active metal Cu were deposited respectively. After the above electrode layers were prepared, Comparative Example 1 was obtained.

[0036] Comparative Example 2: The difference between this comparative example and Comparative Example 1 is that the tungsten-doped indium oxide is subjected to plasma treatment with a plasma power of 100W, while the other preparation methods and parameters remain the same as those in Comparative Example 1.

[0037] The perovskite-titanium batteries described in Examples 1-8 and Comparative Example 1 were tested as follows: Photovoltaic Conversion Efficiency (PCE): The photovoltaic conversion efficiency of the perovskite-titanium solar cells was tested during the aging process. The effective area of ​​all cells was 4.1 cm². The JV curves were obtained under simulated sunlight with AM 1.5 and an irradiance of 100 mW cm⁻² provided by the solar simulator. Efficiency = (Open-circuit voltage x Short-circuit current x Fill factor) / Cell area x Irradiance x 100%.

[0038] Stability: The photoelectric conversion efficiency of the perovskite-titanium battery was characterized by aging under conditions of light stability (maximum output power under simulated sunlight) and high humidity and high thermal stability (85℃, 85%RH). The difference between the photoelectric conversion efficiency of the perovskite-titanium battery after aging for 1000h and that of the perovskite-titanium battery in its initial state was statistically analyzed.

[0039] The above tests show that: Comparing Example 1 with Comparative Example 1 / Comparative Example 2, it can be seen that adding a buffer layer (IMO layer) to the electron transport layer and back electrode layer can improve the photoelectric conversion efficiency to a certain extent. Example 1 maintained the initial high photoelectric conversion efficiency while exhibiting photothermal aging stability degradation of less than 10% after 1000 h, indicating that the molybdenum-doped indium oxide buffer layer played a good role in energy level matching and suppressing interfacial recombination.

[0040] Examples 1 to 4 are molybdenum-doped indium oxide buffer layers with different doping ratios; Comparing Example 3 with Comparative Example 1 / Comparative Example 2, it can be seen that the initial device conversion efficiency is higher than that of Comparative Example 1. However, after photothermal aging, the attenuation rate is much higher than that of Example 1, indicating that doping has a certain effect, but there may be uneven doping due to the low proportion.

[0041] The high doping ratio in Example 4 is worse than that in Comparative Example 1, both in terms of initial device conversion efficiency and aging degradation. This indicates that excessive doping leads to lattice distortion and decreased conductivity. Examples 5 and 6 represent different thicknesses of the molybdenum-doped indium oxide buffer layer; Example 5: Due to the excessively thin molybdenum-doped indium oxide buffer layer, the battery conversion efficiency severely decreased after photothermal aging. In Example 6, the excessively thick molybdenum-doped indium oxide buffer layer resulted in decreased electron mobility, increased interfacial recombination, and increased series resistance. However, the battery conversion efficiency degradation was relatively small after photothermal aging, indicating that it played a certain positive role.

[0042] Examples seven and eight respectively demonstrate plasma treatment using different powers; A comparison of Example 7 and Example 1 shows that the initial device conversion efficiency and photothermal aging degradation performance of Example 7 are acceptable. However, excessive plasma power may cause a sharp drop in mobility, lattice destruction, and the generation of a large number of defects as scattering centers. After aging for 1000 hours, the PCE change rate is too high. However, compared with the comparative example, the PCE efficiency is still higher. A comparison of Example 8 with Example 1 and Comparative Example 1 / Comparative Example 2 shows that the plasma power of Example 8 is too low, which may result in insufficient plasma density and ion energy, and thus cannot effectively overcome the activation energy of surface atoms, leading to a decrease in PCE efficiency.

[0043] In summary, by adding a buffer layer (i.e., an IMO layer) between the electron transport layer and the back electrode layer, a more perfect energy level alignment with the LUMO energy level of mainstream fullerene-based ETLs (such as C60) can be achieved, thereby establishing a lower-loss ohmic contact, significantly reducing the electron extraction barrier, improving the device fill factor, and optimizing the work function. This promotes efficient electron extraction while more effectively suppressing back-interface recombination, which is beneficial for obtaining a higher open-circuit voltage. Furthermore, IMO materials can achieve high conductivity and high mobility after mild annealing or plasma treatment at temperatures below 150°C, or even at room temperature.

[0044] Compared to traditional tungsten-doped indium oxide, this method achieves better energy level matching, superior low-temperature electrical performance, stronger interface stability, and a wider process window at the top electron collection interface of inverted perovskite solar cells.

[0045] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A reverse perovskite solar cell, characterized in that, It includes a transparent conductive layer, a hole transport layer, a perovskite absorption layer, an electron transport layer, and a back electrode layer arranged sequentially. The back electrode layer is a composite structure of a transparent conductive oxide layer and an active metal layer; The electron transport layer is a fullerene-type electron transport layer; The inverted perovskite solar cell further includes a buffer layer located between the electron transport layer and the back electrode layer, and the buffer layer is a molybdenum-doped indium oxide layer.

2. The inverted perovskite solar cell according to claim 1, characterized in that, The molybdenum doping level in the molybdenum-doped indium oxide layer is 1%at-5%at.

3. The inverted perovskite solar cell according to claim 2, characterized in that, The molybdenum doping content in the molybdenum-doped indium oxide layer is 3%at.

4. The inverted perovskite solar cell according to claim 1, characterized in that, The thickness of the buffer layer is 5 nm-15 nm.

5. A reverse perovskite solar cell according to claim 2, characterized in that, The thickness of the buffer layer is 10 nm.

6. The inverted perovskite solar cell according to claim 1, characterized in that, The buffer layer is subjected to plasma treatment.

7. A reverse perovskite solar cell according to claim 6, characterized in that, The plasma processing power is 100W-200W.

8. A method for fabricating an inverted perovskite solar cell, characterized in that, Includes the following steps: A transparent conductive layer is provided, on which a hole transport layer, a perovskite absorption layer, and an electron transport layer are sequentially formed. A buffer layer is formed on the electron transport layer. The buffer layer is a molybdenum-doped indium oxide layer, and the buffer layer is subjected to plasma treatment. A transparent conductive layer and an active metal layer are sequentially formed on the buffer layer as the back electrode.

9. The preparation method according to claim 8, characterized in that, The buffer layer is formed by reactive plasma deposition, and the power of the plasma treatment of the buffer layer is 100W-200W.

10. The preparation method according to claim 8, characterized in that, The thickness of the molybdenum-doped indium oxide layer is 5-15 nm; the molybdenum doping amount of the molybdenum-doped indium oxide layer is 1%at-5%at.

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