A solar cell with M-QDs and OAI co-passivating perovskite and its preparation method

Abstract

The present invention discloses a solar cell using M-QDs and OAI for synergistic co-passivation of perovskite and a preparation method thereof, and the steps are as follows: spin-coat a SnO2-KCl solution on ITO; spin-coat a KF solution on ITO / SnO2-KCl; spin-coat a perovskite precursor solution on ITO / SnO2-KCl / KF; spin-coat an M-QDs solution on ITO / SnO2-KCl / KF / perovskite; spin-coat OAI on ITO / SnO2-KCl / KF / perovskite / M-QDs; spin-coat a spiro-OMeTAD solution on ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI; vacuum-evaporate a gold electrode. A trace amount of DMF added to the M-QDs solution dissolves and recrystallizes the surface perovskite; the functional oleylamine coated on the surface of the M-QDs can block moisture and oxygen, and then passivate the surface through OAI.

Description

Technical Field

[0001] The present invention belongs to the field of material chemistry, and particularly relates to a perovskite solar cell co-passivated by M-QDs and OAI and a preparation method thereof. Background Art

[0002] With the continuous aggravation of environmental pollution and energy crisis, it is urgent for humans to find a new clean energy such as solar energy, geothermal energy, wind energy, ocean energy, biomass energy, and nuclear fusion energy. Solar energy, as a clean energy, is considered the best way to solve the energy problem in the future, and photovoltaic cells that convert solar energy into electrical energy are the most urgently needed energy technologies at present. Compared with traditional silicon solar cells, perovskite solar cells have received extensive attention due to their advantages such as high efficiency, low cost, and simple preparation process. Summary of the Invention

[0003] The purpose of the present invention is to provide a perovskite solar cell co-passivated by M-QDs and OAI and a preparation method thereof. The present invention makes up for the problem of easy formation of interface defects in the preparation process of perovskite thin films.

[0004] By treating the surface of the perovskite thin film with a functional MAPbBr3 quantum dot (M-QDs) solution, a trace amount of DMF in the M-QDs solution dissolves and recrystallizes the surface perovskite; in addition, the quantum dots will aggregate at the grain boundaries to fill the gaps between the grains. At the same time, the functional oleylamine coated on the surface of the M-QDs can block moisture / oxygen, and then passivate the surface with OAI. Thus, a perovskite solar cell with a high open-circuit voltage is prepared, improving the photoelectric conversion efficiency (PCE) and stability of the device.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A perovskite solar cell co-passivated by M-QDs and OAI and a preparation method thereof, characterized by comprising the following steps:

[0007] (1) Ultrasonically clean the ITO substrate with a glass cleaning agent, deionized water, acetone, and ethanol, dry it with nitrogen, and then perform ultraviolet ozone cleaning (UVO) treatment;

[0008] (2) Prepare a SnO2-KCl solution; spin-coat the obtained SnO2-KCl solution on the ITO glass, perform annealing treatment and ultraviolet treatment to obtain an ITO / SnO2-KCl sample;

[0009] (3) Prepare a KF solution; spin-coat the KF solution on the ITO / SnO2-KCl sample obtained in step (2), perform annealing treatment to obtain an ITO / SnO2-KCl / KF sample;

[0010] (4) Spin-coat the perovskite precursor solution on the ITO / SnO2-KCl / KF sample obtained in step (3), and then perform annealing treatment to obtain the ITO / SnO2-KCl / KF / perovskite sample;

[0011] (5) Spin-coat the methylammonium lead bromide quantum dot (M-QDs) solution on the ITO / SnO2-KCl / KF / perovskite sample obtained in step (4) under nitrogen protection to obtain the ITO / SnO2-KCl / KF / perovskite / M-QDs sample;

[0012] (6) Spin-coat the n-octylammonium iodide (OAI) isopropanol solution on the ITO / SnO2-KCl / KF / perovskite / M-QDs sample obtained in step (5) under nitrogen protection to obtain the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI sample;

[0013] (7) Spin-coat the spiro-OMeTAD solution on the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI obtained in step (6) under nitrogen protection to obtain the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD sample;

[0014] (8) Vacuum-evaporate a gold electrode on the sample ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD obtained in step (7) to obtain a perovskite solar cell with the structure of ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au.

[0015] Preferably, in step (2), the preparation process of the SnO2-KCl solution is as follows: Dissolve KCl in deionized water to prepare a KCl solution with a concentration of 5 mg / ml, and then mix the SnO2 aqueous colloidal solution with a concentration of 15 wt% and the 5 mg / ml KCl solution in a volume ratio of 2:1 to prepare the SnO2-KCl solution. In step (2), annealing means annealing at 100 °C for 5 minutes and then annealing at 150 °C for 10 minutes.

[0016] Preferably, in step (3), the KF solution is a 0.3 mg / ml aqueous solution. In step (3), annealing means annealing at 100 °C for 5 minutes and then annealing at 120 °C for 10 minutes.

[0017] Preferably, in step (4), the perovskite precursor solution is specifically Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br0.15 )3 (abbreviated as CFM) perovskite precursor solution, and the specific preparation process is as follows: Dissolve CsI, FAI, MAI, PbI2, and PbBr2 in a mixed solution of DMF and DMSO with a volume ratio of 8.5:1.5 at a molar ratio of 0.05:0.81:0.14:0.78:0.22. Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 )3 has a concentration of 1.4 M, and then stir for 10 h to 15 h to obtain the perovskite precursor solution; in step (4), annealing means annealing at 100 °C for 5 minutes and then annealing at 120 °C for 10 minutes.

[0018] Preferably, in step (5), the concentration of methylammonium lead bromide quantum dot (M-QDs) solution is 0.3 mM, and the specific synthesis process is as follows: First, dissolve 0.44 mmol of MABr and 0.44 mmol of PbBr2 in 1 mL of DMF and stir at 60 °C for 30 min. Then add 40 μL of oleylamine and stir at room temperature for 10 min to obtain a clear solution, denoted as solution A. Second, add 180 μL of oleic acid to 8 mL of toluene solution and stir vigorously at room temperature for 30 min, denoted as solution B. Third, during the continuous vigorous stirring of solution B, add 0.5 mL of solution A, and the color of the mixed solution immediately turns yellow. Finally, after centrifuging at 4000 rpm for 20 min, a green supernatant M-QDs solution for passivating the perovskite film in the first step is obtained. The concentration of M-QDs in the green solution is quantified to be about 9 mM and diluted with toluene to 0.3 mM for experiments.

[0019] Preferably, in step (6), dissolve OAI in isopropanol and stir for 10 h to 15 h to prepare an OAI isopropanol solution with a concentration of 2 mg / mL.

[0020] Preferably, in step (7), the preparation process of the spiro-OMeTAD solution is as follows: Take 72.5 mg of spiro-OMeTAD, add 1 mL of chlorobenzene, 28.5 μL of 4-tert-butylpyridine, and 18 μL of lithium bis(trifluoromethanesulfonyl)imide, and stir for 10 h to 15 h to obtain it.

[0021] Preferably, the spin coating amount of the KF solution is 80 - 120 μL, the spin coating amount of the MAPbBr3 quantum dot (M-QDs) solution is 80 - 120 μL, and the spin coating amount of the OAI solution is 80 - 120 μL.

[0022] The M-QDs and OAI co-passivated perovskite solar cells prepared by the above preparation method. Specifically, the thickness of the SnO2 layer is 40 nm, the thickness of the perovskite layer is 450 nm, the thickness of the spiro-OMeTAD layer is 150 nm, and the thickness of the gold is 80 nm.

[0023] The present invention remedies the problem of easy formation of interface defects during the preparation of perovskite thin films. By treating the surface of the perovskite thin film with a functional M-QDs solution, trace DMF added to the M-QDs solution dissolves and recrystallizes the surface perovskite. In addition, the quantum dots will aggregate at the grain boundaries to fill the gaps between the grains. At the same time, the functional oleylamine coated on the surface of the M-QDs can block moisture / oxygen, and then it is passivated on the surface by OAI. Thus, perovskite solar cells with high open-circuit voltage are prepared, improving the photoelectric conversion efficiency and stability of the device. Brief Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the cell structure;

[0025] Figure 2 It is a transmission electron microscope (TEM) image of methylammonium lead bromide quantum dots;

[0026] Figure 3 It is a current-voltage ( J-V ) curve comparison diagram of the solar cells of ITO / SnO2-KCl / KF / perovskite / spiro-OMeTAD / Au and ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au (abbreviated as CFM and CFM / M-QDs / OAI in the figure);

[0027] Figure 4 It is a scanning electron microscope (SEM) image of two kinds of thin films: (a) ITO / SnO2-KCl / KF / perovskite and (b) ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI;

[0028] Figure 5 It is an X-ray diffraction (XRD) pattern of two kinds of thin films: ITO / SnO2-KCl / KF / perovskite and ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI (abbreviated as CFM and CFM / M-QDs / OAI in the figure);

[0029] Figure 6For the encapsulated ITO / SnO2-KCl / KF / perovskite / spiro-OMeTAD / Au and ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au (abbreviated as CFM and CFM / M-QDs / OAI in the figure) solar cells (a) long-term stability in air environment (b) thermal stability under continuous heating at 85 °C in nitrogen environment (c) light stability under continuous illumination in nitrogen environment (light intensity is 100 mW cm -2 ) Specific embodiments

[0030] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the protection scope of the present invention is not limited thereto.

[0031] Example 1

[0032] A preparation method of a solar cell with M-QDs and OAI co-passivating perovskite is as follows:

[0033] (1) Prepare SnO2-KCl solution in air: The preparation process of SnO2-KCl solution is as follows: Dissolve 5 mg of potassium chloride in 1 ml of deionized water, stir for 12 h (prepare it the day before and use it the next day. If it is used immediately after preparation, stir for about 1 h), prepare a KCl solution with a mass concentration of 5 mg / ml, and then mix the SnO2 aqueous colloid solution with a mass concentration of 15 wt% (purchased from AlfaAesar) and the prepared KCl solution in a volume ratio of 2:1, and stir for 30 minutes to obtain SnO2-KCl solution.

[0034] (2) Prepare KF solution in air: Dissolve 3 mg of KF crystals in 10 mL of deionized water, stir for 12 h, and prepare a 0.3 mg / mL KF aqueous solution.

[0035] (3) Prepare Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 )3 (abbreviated as CFM) perovskite precursor solution: Dissolve CsI, FAI, MAI, PbI2 and PbBr2 in a mixed solution of DMF and DMSO with a volume ratio of 8.5:1.5 at a molar ratio of 0.05:0.81:0.14:0.78:0.22. Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15) The concentration of is 1.4 M, then stir for 12 h, and finally obtain the perovskite precursor solution.

[0036] (4) The specific synthesis process of the MAPbBr3 quantum dot (M-QDs) solution is as follows: First, dissolve 0.44 mmol of MABr and 0.44 mmol of PbBr2 in 1 mL of DMF and stir at 60 °C for 30 min. Then add 40 μL of OLA (oleylamine) and stir at room temperature for 10 min to obtain a clear solution, denoted as Solution A. Second, add 180 μL of OA (oleic acid) to 8 mL of toluene solution and stir vigorously at room temperature for 30 min, denoted as Solution B. Third, during the continuous vigorous stirring of Solution B, add 0.5 mL of Solution A, and the color of the mixed solution immediately turns yellow. Finally, after centrifuging at 4000 rpm for 20 min, obtain a green supernatant M-QDs solution and a yellow precipitate. The concentration of M-QDs in the green supernatant solution is quantitatively about 9 mM. (Before centrifugation, the concentration of the M-QDs quantum dot solution is 27.5 mM. After centrifugation at 4000 rpm, a green supernatant and a yellow precipitate will be produced (the precipitate is quantum dots with slightly larger particles). Here, 9 mM is only the concentration of the quantum dots in the green supernatant. Two measurement methods were used to calculate the concentration. First, weigh the mass of the centrifuge tube, then transfer the quantum dot solution with a concentration of 27.5 mM into this centrifuge tube for centrifugation at 4000 rpm (the centrifuge power is 750 W). After centrifugation, take out the supernatant, dry the yellow precipitate in a vacuum drying oven with a power of 900 W (room temperature), and then weigh the mass of the centrifuge tube and its yellow substance. From this, the mass of the yellow precipitate is calculated to be about 71 mg. Through the total mass of MABr and PbBr2 weighed before, the mass of the quantum dots contained in the green supernatant can be calculated, which is about 35 mg after calculation. The solvent is 8 mL, and finally, the concentration of M-QDs in the green solution is quantitatively about 9 mM. Second, weigh the mass of a clean weighing paper, drop 2 mL of the green supernatant onto the weighing paper, air-dry it naturally, and weigh the mass of the weighing paper and the solid on the weighing paper. The mass of the solid is calculated to be about 8.8 mg, and the concentration of the green supernatant is inferred to be about 9 mM. The results obtained by the two calculation methods can confirm each other, and thus the concentration of the green supernatant is about 9 mM.) Dilute it with toluene to 0.3 mM for the experiment.

[0037] (5) Prepare a solution of n-octylammonium iodide (OAI) in a nitrogen glove box (in all steps using the glove box, ensure that the water and oxygen content are both less than 0.1 ppm): Dissolve 2 mg of OAI crystals in 1 mL of isopropanol to prepare a 2 mg / mL alcohol solution, and stir for 12 h to obtain the OAI solution.

[0038] (6) Preparation of spiro-OMeTAD solution: The preparation method of the spiro-OMeTAD solution is to weigh 72.5 mg of spiro-OMeTAD powder in a small sample vial, then add 1 mL of chlorobenzene, 18 μL of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI), and 28.5 μL of 4-tert-butylpyridine, and stir for 12 h to obtain the spiro-OMeTAD solution.

[0039] (7) The ITO substrate with an area of 2.0 cm × 2.0 cm is ultrasonically cleaned (ultrasonic power is 800 W) with glass cleaner, deionized water, acetone, and ethanol in turn for 45 minutes each, then dried with nitrogen, and finally treated with ultraviolet ozone cleaning (UVO);

[0040] (8) Take 100 μL of the prepared SnO2-KCl solution in air and spin-coat it on the ITO glass at a rotation speed of 5500 rpm for 10 s. After spin-coating, anneal at 100 °C for 5 minutes first, then anneal at 150 °C for 10 minutes. After all annealing is completed, perform ultraviolet treatment for 1 hour (temperature is about 50 °C) to obtain the ITO / SnO2-KCl sample, and the thickness of the SnO2-KCl film is about 40 nm;

[0041] (9) Spin-coat 100 μL of the KF solution on the ITO / SnO2-KCl at a rotation speed of 3000 rpm for 10 s. After spin-coating, anneal at 100 °C for 5 minutes first, then anneal at 120 °C for 10 minutes to obtain the ITO / SnO2-KCl / KF sample (take 100 μL for spin-coating, and it is not certain that a continuous thin film can be formed after KF spin-coating and the film is very thin, and the SEM test accuracy is not enough to measure its exact thickness);

[0042] (10) The ITO / SnO2-KCl / KF sample is spin-coated with 30 μL (a total of 30 μL) of Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 )3 perovskite precursor solution under the protection of nitrogen (this step is carried out in a glove box with water and oxygen content less than 0.1 ppm) at rotation speeds of 1000 rpm (low speed) and 4500 rpm (high speed) respectively for 5 s and 20 s of spin-coating time. Anneal at 100 °C for 5 minutes first, then anneal at 120 °C for 10 minutes to obtain the ITO / SnO2-KCl / KF / perovskite sample, Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15) The thickness of the 3 - layer is about 450 nm (the main factors affecting the thickness include solution concentration, spin - coating speed, and environmental temperature and humidity conditions, etc. In this application, KF treatment is used before spin - coating perovskite, and the wettability of the obtained samples has a slight difference. Usually, when the wettability is good, less amount is used, and vice versa);

[0043] (11) The ITO / SnO2 - KCl / KF / perovskite sample is spin - coated with 100 μL of MAPbBr3 quantum dot (M - QDs) solution at 5000 rpm for 10 s under nitrogen protection (this step is carried out in a glove box with water and oxygen content both less than 0.1 ppm), and then air - dried naturally to obtain the ITO / SnO2 - KCl / KF / perovskite / M - QDs sample (the quantum dot film is very thin, and its precise thickness cannot be measured either);

[0044] (12) The ITO / SnO2 - KCl / KF / perovskite / M - QDs sample is spin - coated with 100 μL of OAI solution at 5000 rpm for 10 s under nitrogen protection (this step is carried out in a glove box with water and oxygen content both less than 0.1 ppm), and then air - dried naturally to obtain the ITO / SnO2 - KCl / KF / perovskite / M - QDs / OAI sample (after spin - coating and air - drying naturally, the OAI film is very thin, and its precise thickness cannot be measured either);

[0045] (13) Spin - coat 30 μL of spiro - OMeTAD solution on the ITO / SnO2 - KCl / KF / perovskite / M - QDs / OAI sample (this step is carried out in a glove box with water and oxygen content both less than 0.1 ppm) at 4500 rpm for 20 s, and then air - dried naturally to obtain the ITO / SnO2 - KCl / KF / perovskite / M - QDs / OAI / spiro - OMeTAD sample. The thickness of the spiro - OMeTAD layer is about 150 nm;

[0046] (14) Finally, the obtained sample is vacuum - evaporated with a gold electrode (thickness 80 nm), and the battery assembly is completed. The structure is as Figure 1 shown.

[0047] Omitting steps (4), (5), (11) and (12) gives a solar cell with the structure ITO / SnO2 - KCl / KF / perovskite / spiro - OMeTAD / Au.

[0048] Figure 2 is the transmission electron microscope (TEM) image of methylammonium lead bromide quantum dots. The size and quality of the prepared M - QDs are measured by TEM. As Figure 2 can be seen, the M - QDs quantum dots have uniform grain size. The statistical data ( Figure 2 in the insertFigure 2 ) The obtained average grain size is 8.6 nm, indicating their quantum properties and orderly arrangement. The lattice fringes ( Figure 2 inserted in Figure 1 ) have a lattice spacing of 2.83 Å, which is consistent with the (0 0 2) crystal plane of the XRD pattern of methylammonium lead bromide quantum dots.

[0049] Figure 3 Figure showing the current-voltage ( J-V ) curves of solar cells with structures ITO / SnO2-KCl / KF / perovskite / spiro-OMeTAD / Au and ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au (abbreviated as CFM and CFM / M-QDs / OAI in the figure). It can be seen from the figure that the overall photovoltaic performance of the solar cell device based on the synergistic co-passivation of perovskite by M-QDs and OAI is significantly improved. Specifically, the energy conversion efficiency, open-circuit voltage, short-circuit current, and fill factor of the ITO / SnO2-KCl / KF / perovskite / spiro-OMeTAD / Au cell are 18.97%, 1.16 V, 22.40 mA cm -1 and 0.73 respectively; the energy conversion efficiency, open-circuit voltage, short-circuit current, and fill factor of the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au cell are 22.01%, 1.20 V, 24.79 mA cm -1 and 0.74 respectively.

[0050] Figure 4 Scanning electron microscope (SEM) images of two kinds of thin films: (a) ITO / SnO2-KCl / KF / perovskite and (b) ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI. Figure 4 Comparing (a) and (b) in the figure, it can be seen that the grain boundaries of the perovskite thin film become blurred, indicating that trace amounts of DMF dissolve and recrystallize the surface perovskite. The presence of quantum dots at the grain boundaries also fully demonstrates the filling effect of quantum dots on the crystal plane gaps. The appearance of the wrinkled structure on the perovskite surface is due to the action of OAI. Thus, it can be obtained that the synergistic co-passivation of M-QDs and OAI has a good effect on the perovskite thin film.

[0051] Figure 5 XRD patterns of two kinds of thin films: (a) ITO / SnO2-KCl / KF / perovskite and (b) ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI (abbreviated as CFM and CFM / M-QDs / OAI in the figure). The significantly enhanced peak intensity also indicates that the crystallinity of the perovskite thin film becomes better after the synergistic co-passivation of M-QDs and OAI.

[0052] Figure 6 Comparison chart of the long-term stability of ITO / SnO2-KCl / KF / perovskite / spiro-OMeTAD / Au and ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au (abbreviated as CFM and CFM / M-QDs / OAI in the figure) solar cells Figure 6 In (a), the change of PCE with time of two unencapsulated devices in air (temperature about 25 °C, humidity about 30%) is recorded. After storing for 2000 hours, the photoelectric conversion efficiency of the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au device is greater than 90% of the initial PCE, while the photoelectric conversion efficiency of the ITO / SnO2-KCl / KF / perovskite / spiro-OMeTAD / Au device is less than 50% of the initial PCE; Figure 6 In (b), the change of PCE with time of two unencapsulated devices under continuous heating at 85 °C in a nitrogen environment is recorded. The photoelectric conversion efficiency of the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au device is still greater than 70% of the initial PCE after storing for 2000 hours, while the photoelectric conversion efficiency of the ITO / SnO2-KCl / KF / perovskite / spiro-OMeTAD / Au device is lower than 50% of the initial PCE at 400 hours; Figure 6 In (c), the change of PCE with time of two unencapsulated devices under continuous illumination with a light intensity of 100 mW cm -2 is recorded. The photoelectric conversion efficiency of the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au device is still greater than 80% of the initial PCE after storing for 1000 hours, while the photoelectric conversion efficiency of the ITO / SnO2-KCl / KF / perovskite / spiro-OMeTAD / Au device is lower than 50% of the initial PCE at 300 hours; It can be clearly seen that the stability of the solar cell with M-QDs and OAI co-passivating perovskite is greatly enhanced.

[0053] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any change or replacement that can be thought of without creative work should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.

Claims

1. A method for preparing a perovskite solar cell co-passivated by M-QDs and OAI, characterized in that, It includes the following steps: (1) Clean the ITO substrate, dry it with nitrogen, and then perform ultraviolet ozone cleaning treatment; (2) Prepare the SnO2-KCl solution; spin-coat the obtained SnO2-KCl solution on the ITO glass, perform annealing treatment and ultraviolet treatment to obtain the ITO / SnO2-KCl sample; (3) Prepare the KF solution; spin-coat the KF solution on the ITO / SnO2-KCl sample obtained in step (2), and perform annealing treatment to obtain the ITO / SnO2-KCl / KF sample; (4) Spin-coat the perovskite precursor solution on the ITO / SnO2-KCl / KF sample obtained in step (3) under nitrogen protection, and then perform annealing treatment to obtain the ITO / SnO2-KCl / KF / perovskite sample; (5) Spin-coat the MAPbBr3 quantum dot (M-QDs) solution on the ITO / SnO2-KCl / KF / perovskite sample obtained in step (4) under nitrogen protection to obtain the ITO / SnO2-KCl / KF / perovskite / M-QDs sample; the concentration of the MAPbBr3 quantum dot (M-QDs) solution is 0.3 mM, and the specific synthesis process is as follows: First, dissolve 0.44 mmol of MABr and 0.44 mmol of PbBr2 in 1 mL of DMF, and stir at 60±5°C for 20 min to 40 min; then add 40 μL of oleylamine and stir at room temperature until a clear solution is obtained, denoted as solution A; Second, add 180 μL of oleic acid to 8 mL of toluene solution and stir at room temperature for 20 min to 40 min, denoted as solution B; Third, during the continuous stirring of solution B, add 0.5 mL of solution A, and the color of the mixed solution immediately turns yellow; Finally, centrifuge to obtain the upper green clear solution, which is the M-QDs solution. The concentration of M-QDs in the green solution is 9 mM, and the solution is diluted with toluene to obtain a M-QDs solution with a concentration of 0.3 mM for standby; (6) Spin-coat the n-octylammonium iodide (OAI) isopropanol solution on the ITO / SnO2-KCl / KF / perovskite / M-QDs sample obtained in step (5) under nitrogen protection to obtain the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI sample; (7) Spin-coat the spiro-OMeTAD solution on the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI obtained in step (6) under nitrogen protection to obtain the ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD sample; (8) Vacuum-evaporate the gold electrode on the sample ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD obtained in step (7) to obtain a perovskite solar cell with the structure of ITO / SnO2-KCl / KF / perovskite / M-QDs / OAI / spiro-OMeTAD / Au.

2. The preparation method of the perovskite solar cell co-passivated by M-QDs and OAI according to claim 1, wherein, In step (2), the preparation process of the SnO2-KCl solution is as follows: Dissolve KCl in deionized water to prepare a KCl solution with a concentration of 5 mg / ml, and then mix a SnO2 aqueous colloidal solution with a concentration of 15 wt% and the 5 mg / ml KCl solution in a volume ratio of 2:1 to prepare the SnO2-KCl solution.

3. The solar cell prepared by co-passivating perovskite with M-QDs and OAI according to claim 1, characterized in that, In step (3), the KF solution is an aqueous KF solution with a concentration of 0.3 mg / mL.

4. The solar cell based on the co-passivation of M-QDs and OAI for perovskite according to claim 1 and its preparation method, characterized in that, The perovskite precursor solution is specifically Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 )3 perovskite precursor solution. The specific preparation process is as follows: CsI, FAI, MAI, PbI2 and PbBr2 are dissolved in a mixed solution of DMF and DMSO with a volume ratio of 8.5:1.5 at a molar ratio of 0.05:0.81:0.14:0.78:0.

22. The molar volume of Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 )3 is 1.4 mol / L, and then stirred for 10 h to 15 h to obtain the perovskite precursor solution.

5. The M-QDs and OAI co-passivated perovskite solar cell according to claim 1 and its preparation method are characterized in that, In step (6), dissolve OAI in isopropanol and stir for 10 h to 15 h to prepare an OAI isopropanol solution with a concentration of 2 mg / mL.

6. The solar cell using M-QDs and OAI to synergistically co-passivate perovskite according to claim 1 and its preparation method, characterized in that, In step (7), the preparation process of the spiro-OMeTAD solution is as follows: Take 72.5 mg of spiro-OMeTAD, add 1 mL of chlorobenzene, 28.5 μL of 4-tert-butylpyridine, and 18 μL of lithium bis(trifluoromethanesulfonyl)imide, and stir for 10 h to 15 h to obtain it.

7. The solar cell with M-QDs and OAI co-passivating perovskite according to claim 1 and its preparation method, characterized in that, In step (2), annealing means annealing at 100 °C for 5 minutes first and then at 150 °C for 10 minutes; in step (3), annealing means annealing at 100 °C for 5 minutes and then at 120 °C for 10 minutes; in step (4), annealing means annealing at 100 °C for 5 minutes and then at 120 °C for 10 minutes.

8. A perovskite solar cell co-passivated by M-QDs and OAI prepared by the preparation method according to any one of claims 1 to 7.

9. The perovskite solar cell according to claim 8, wherein, The thickness of the SnO2-KCl layer is 40 nm, the thickness of the perovskite layer is 450 nm, the thickness of the spiro-OMeTAD layer is 150 nm, and the thickness of the gold is 80 nm.

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