A perovskite quantum dot solar cell and its preparation method

Abstract

The present invention relates to a perovskite quantum dot solar cell and a preparation method thereof. The cell structure includes a conductive glass substrate, an electron transport layer, a quantum dot light absorption layer, a hole transport layer, and a metal electrode: The quantum dot light absorption layer is obtained by treating a perovskite quantum dot thin film with a structure of ABX3 with a mixed solution of an ionic liquid and a certain acid ester to synergistically achieve ligand exchange and surface defect passivation. The present invention addresses the contradiction between the conductivity and material stability in the light absorption layer of existing perovskite quantum dot solar cells. By using an ionic liquid with adjustable solubility in acid esters to treat the perovskite quantum dot thin film to remove insulating ligands, stabilize the quantum dot structure, and effectively passivate the surface defects of the quantum dots, a simple and universal method is provided, enabling the prepared perovskite quantum dot solar cell to achieve improvements in efficiency and stability. It is also applicable to optoelectronic device fields such as LEDs and photodetectors based on perovskite quantum dots.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar photovoltaics, and particularly relates to a perovskite quantum dot solar cell and a preparation method thereof. Background Art

[0002] Facing the current energy crisis and environmental problems, solar energy is an inexhaustible sustainable clean energy; and solar cells can directly convert solar energy into electrical energy without carbon emissions. In recent years, lead halide perovskite materials have been widely applied in solar cells due to their unique advantages such as high absorption coefficient, long exciton lifetime, low exciton binding energy, and long carrier diffusion length. In addition, with the characteristics of low cost and liquid-phase processing, perovskite materials are considered a potential new photovoltaic material to replace silicon and are currently favored by the academic and industrial communities. With the development of perovskite polycrystalline thin films, perovskite quantum dot semiconductor materials have emerged. Due to their unique advantages such as adjustable bandgap, multipolaron effect, and confinement effect, they are widely used in optoelectronic fields such as solar cells, LEDs, and photodetectors. Since 2016, when CsPbI3 quantum dots were first introduced into solar cells and a photoelectric conversion efficiency of 10.77% was obtained, in just 5 years, the efficiency of perovskite quantum dot solar cells has exceeded 17%, showing potential application value.

[0003] However, during the synthesis process of perovskite quantum dots, a large amount of oleic acid and oleylamine ligands are wrapped on the surface. These ligands seriously hinder charge transport after the quantum dots form a film, seriously affecting the efficiency of perovskite quantum dot solar cells. Therefore, during the film-forming process, polar solvents are needed to wash the ligands of the quantum dots to remove the excess ligands. While removing the ligands, more defects will be generated on the surface of the quantum dots. These defects will not only cause charge transport to be blocked, but also become the erosion sites of water and oxygen in the air, leading to material degradation. In addition, the surface chemical environment of perovskite quantum dots is greatly affected by the material composition. Through Fourier transform infrared spectroscopy and first-principles calculations, it is found that compared with all-inorganic CsPbI3 perovskite quantum dots, the surface ligand binding energy of organic-inorganic hybrid FAPbI3 quantum dots is larger, especially for oleylamine ligands. The binding energy of FAPbI3 quantum dots is close to twice that of CsPbI3 quantum dots. This is because the A-site FA + cations can form hydrogen bonds or van der Waals bonds with the ligands, so that the common anti-solvents for CsPbI3 quantum dots (such as methyl acetate and ethyl acetate) cannot be better adapted to FAPbI3 quantum dots. Protonated solvents, such as alcohols, although can remove surface ligands, but due to their strong polarity, they are extremely likely to cause quantum dot degradation (see references: Joule 2018, 2, 1866-1878; Joule 2022, 6, 1-22).

[0004] Therefore, it is a key problem to be solved urgently at present to find a universal method that can be used for ligand exchange and passivation of both all-inorganic perovskite quantum dots and organic-inorganic hybrid perovskite quantum dots, and to achieve the balance between charge transport and device (material) stability in perovskite quantum dot solar cells. Summary of the Invention

[0005] Aiming at the deficiencies existing in solving the balance between conductivity and stability during the film formation process of existing perovskite quantum dot optoelectronic devices, the present invention provides a perovskite quantum dot solar cell and a preparation method thereof. By adopting a universal surface treatment process, the double improvement of the efficiency and stability of the perovskite quantum dot solar cell is realized.

[0006] The technical solution for achieving the purpose of the present invention is to provide a perovskite quantum dot solar cell, which includes a conductive glass substrate, an electron transport layer, a quantum dot light absorption layer, a hole transport layer, and a metal electrode: the quantum dot light absorption layer is obtained by treating a perovskite quantum dot film with a structure of ABX3 with a mixed solution of an ionic liquid and a certain acid ester, and realizing ligand exchange and surface defect passivation synergistically. Among them, A is formamidine (FA + , CH(NH2)2 + ) or cesium (Cs + ) cation, B is Pb 2+ or Sn 2+ , X is I - or Br - anion; the ionic liquid includes formamidine thiocyanate, methylammonium thiocyanate, methylammonium acetate, methylammonium formate, formamidine formate, methyltrioctylammonium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium chloride, or 1-hexyl-3-methylimidazolium iodide; the certain acid ester solution includes methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl butyrate.

[0007] In the perovskite quantum dot solar cell of the present invention, the size of the perovskite quantum dots with the ABX3 structure in the quantum dot light absorption layer is 5 to 20 nanometers, and the thickness of the perovskite quantum dot light absorption layer is 100 to 800 nanometers.

[0008] The electron transport layer is one of PCBM, TiO2, SnO2, or ZnO thin films, and the thickness of the electron transport layer is 10 to 200 nanometers.

[0009] The hole transport layer is one of PTAA, PTB7, Spiro-OMTAD, PTBT-Th, P3HT, or PBDB-T, and the thickness of the hole transport layer is 10 to 200 nanometers.

[0010] The metal electrode is MoOx / Ag, MoO x / Al or one of Au, with a thickness of 20 to 200 nanometers.

[0011] The technical solution of the present invention also includes a preparation method of a perovskite quantum dot solar cell, comprising the following steps:

[0012] (1) Spin-coat an electron transport material on a conductive glass substrate to obtain an electron transport layer;

[0013] (2) Prepare a perovskite quantum dot light absorption layer

[0014] (a) Deposit a perovskite quantum dot solution on the electron transport layer by spin-coating to obtain a perovskite quantum dot thin film with a structure of ABX3, where A is formamidinium (FA + , CH(NH2)2 + ) or cesium (Cs + ) cation, B is Pb 2+ or Sn 2+ , X is I - or Br - anion;

[0015] (b) Drop a mixed solution of an ionic liquid and an ester of a certain acid on the quantum dot thin film, keep it for 2 to 10 seconds, spin-dry it, and perform ligand exchange and surface defect passivation treatment; the ionic liquid includes formamidinium thiocyanate, methylammonium thiocyanate, methylammonium acetate, methylammonium formate, formamidinium formate, methyltrioctylammonium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium chloride or 1-hexyl-3-methylimidazolium iodide; the solution of the ester of a certain acid includes methyl formate, ethyl formate, methyl acetate, ethyl acetate, ethyl propionate, methyl butyrate, ethyl butyrate; in the said mixed solution, the concentration of the ionic liquid is 0.001 to 2 mg / ml;

[0016] (c) Repeat steps (a) to (b) 2 to 10 times to obtain a perovskite quantum dot light absorption layer;

[0017] (3) Prepare a hole transport layer on the light absorption layer;

[0018] (4) Evaporate a metal electrode on the hole transport layer to obtain a perovskite quantum dot solar cell.

[0019] The preferred solution is: the thickness of the perovskite quantum dot light absorption layer is 100 to 800 nanometers.

[0020] The principle of the present invention is as follows: during the preparation process of perovskite quantum dot solar cells, the original pure solution of a certain acid ester is replaced with a mixed solution of an ionic liquid with adjustable solubility and a certain acid ester to treat the quantum dot film. Taking the formamidinium thiocyanate ionic liquid as an example, on the one hand, the formamidinium cation can effectively exchange the long-chain oleylamine ligand as a short-chain ligand, while the thiocyanate anion can effectively remove the long-chain oleic acid ligand, thereby increasing the electron coupling of the quantum dots and promoting charge transport; on the other hand, the ionic liquid with functional groups can effectively passivate the surface vacancies of the quantum dots and passivate the uncoordinated Pb 2+ , thus reducing the adverse effects brought by defect-induced non-radiative recombination during the charge transport process. This effective passivation reduces the erosion of water and oxygen in the air on the defect sites, thereby improving the stability of the device. Especially for organic-inorganic hybrid perovskite quantum dots with relatively high surface ligand binding energy, the present invention can achieve effective removal of ligands and surface passivation through concentration regulation; for all-inorganic perovskite quantum dots with relatively low surface ligand binding energy, the present invention can simply reduce the concentration of the ionic liquid to achieve the same effect.

[0021] Compared with the prior art, the technical solution provided by the present invention has the following advantages:

[0022] 1. The present invention has developed a preparation process for perovskite quantum dot solar cells, abandoning the original two-step surface treatment process. By introducing an ionic liquid with adjustable solubility in a low-polarity solvent (such as a certain acid ester) to treat the surface of the quantum dot film, it can not only effectively achieve ligand exchange and synchronously passivate the surface defects generated due to ligand removal, but also not damage the structural stability of the perovskite quantum dots.

[0023] 2. The surface treatment process provided by the present invention has broad universality and is applicable to all-inorganic perovskite quantum dots and organic-inorganic hybrid perovskite quantum dots; through this process, the double improvement of device efficiency and stability is achieved.

[0024] 3. The technical solution provided by the present invention can not only be applied to perovskite quantum dot solar cells, but also be widely applied to the technical fields of the preparation of optoelectronic devices such as perovskite quantum dot LEDs and photodetectors. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the device structure of the perovskite quantum dot solar cell provided by the present invention;

[0026] Figure 2 It is a scanning electron microscope image of the interface of the perovskite quantum dot solar cell prepared in Example 1 of the present invention;

[0027] Figure 3Line graph of solution concentration and device efficiency corresponding to the solar cell prepared by treating the FAPbI3 quantum dot film with a formamidinium thiocyanate ionic liquid - methyl acetate solution in Example 1 of the present invention;

[0028] Figure 4 Current density - voltage (J - V) curve graph of the perovskite quantum dot solar cell prepared in Example 1 of the present invention;

[0029] Figure 5 Air stability curve graph of the perovskite quantum dot solar cell prepared in Example 1 of the present invention;

[0030] Figure 6 Current density - voltage (J - V) curve graph of the perovskite quantum dot solar cell prepared in Example 2 of the present invention;

[0031] Figure 7 Current density - voltage (J - V) curve graph of the perovskite quantum dot solar cell prepared in Example 3 of the present invention;

[0032] Figure 8 Current density - voltage (J - V) curve graph of the perovskite quantum dot solar cell prepared in Example 4 of the present invention.

[0033] In the figure, 1. Transparent conductive glass; 2. Electron transport layer; 3. Light absorption layer; 4. Hole transport layer; 5. Metal electrode. Detailed implementation manners

[0034] The technical solution of the present invention will be further described below in conjunction with the drawings and embodiments.

[0035] Example 1

[0036] See the appendix Figure 1 , which is a schematic diagram of the device structure of the perovskite quantum dot solar cell provided by the present invention; The battery preparation includes the following steps: An electron transport layer 2, a perovskite quantum dot light absorption layer 3, a hole transport layer 4, and a metal electrode 5 are sequentially prepared on the conductive glass substrate 1.

[0037] This example provides a FAPbI3 perovskite quantum dot solar cell, and the specific preparation steps are as follows:

[0038] Step 1, on a clean fluorine - doped tin oxide (abbreviated as FTO) conductive glass substrate, a dense TiO2 thin film with a thickness of about 40 nanometers is prepared by chemical bath deposition to obtain an electron transport layer, and it is annealed at 200 degrees Celsius for 30 minutes before quantum dot deposition;

[0039] Step 2: Under an air atmosphere with a humidity of 10%, spin-coat and wash the perovskite quantum dot film layer by layer on the basis of the electron transport layer to obtain a perovskite quantum dot light absorption layer. In this embodiment, the specific method is as follows: Dissolve the synthesized FAPbI3 quantum dots in n-octane at a concentration of 75 mg / mL, spin-coat for 15 s and 20 s at 1000 rpm and 2000 rpm respectively; then drop a methyl acetate solution of an ionic liquid containing formamidinium thiocyanate with a concentration of 0.1 mg / mL (optimal concentration) onto the quantum dot film, hold for 5 s, and then spin-dry at 2000 rpm; repeat the above process of spin-coating and washing 5 times to obtain a perovskite quantum dot light absorption layer with a thickness of about 400 nm.

[0040] Step 3: Spin-coat the polymer PTAA on the perovskite quantum dot light absorption layer to form a hole transport layer. The specific method is as follows: Dissolve PTAA in toluene to prepare a solution with a concentration of 15 mg / mL, dope 5% by mass of tris(pentafluorophenyl)borane, and spin-coat at a rotation speed of 3000 rpm for 40 s to form a hole transport layer with a thickness of about 80 nm.

[0041] Step 4: Vacuum thermally evaporate metal electrodes on the hole transport layer. The thicknesses of MoO x and Ag are 8 nm and 120 nm respectively to obtain an FAPbI3 perovskite quantum dot solar cell.

[0042] See Appendix Figure 2 , which is a scanning electron microscope image of the interface of the perovskite quantum dot solar cell provided in this embodiment.

[0043] See Figure 3 in the accompanying drawings. It is a line graph of the solution concentration and device efficiency corresponding to the solar cell prepared by treating the FAPbI3 quantum dot film with a formamidinium thiocyanate ionic liquid-methyl acetate solution; among them, the number of perovskite quantum dot layers in the device during the concentration optimization process is 3 layers, and the thickness is 300 nm.

[0044] See Appendix Figure 4 , which is a current density-voltage (J-V) curve graph of the perovskite quantum dot solar cell provided in this embodiment using FAPbI3 quantum dots as the light absorption layer and PTAA as the hole transport layer; under the standard test conditions of AM 1.5G, 100 mW / cm 2 , the short-circuit current density of the measured device is 18.45 mA / cm 2 , the open-circuit voltage is 1.15 V, the fill factor is 68.2%, and the photoelectric conversion efficiency is 14.47%.

[0045] See Appendix Figure 5, which is the air storage stability curve of the FAPbI3 perovskite quantum dot solar cell provided in this embodiment. The stored air humidity is 25-30%. After 25 days of storage, the efficiency of the unencapsulated device can still maintain 81% of the original efficiency.

[0046] Example 2

[0047] This embodiment provides a CsPbI3 perovskite quantum dot solar cell, and the structure is as Figure 1 shown. The preparation of the battery includes the following steps: sequentially prepare an electron transport layer 2, a perovskite quantum dot light absorption layer 3, a hole transport layer 4, and a metal electrode 5 on a conductive glass substrate 1.

[0048] The specific steps are as follows:

[0049] Step 1, on a clean fluorine-doped tin oxide (abbreviated as FTO) conductive glass substrate, prepare a dense TiO2 thin film with a thickness of about 40 nanometers by chemical bath deposition to obtain an electron transport layer, and anneal it at 200 °C for 30 minutes before quantum dot deposition;

[0050] Step 2, in an air atmosphere with a humidity of 10%, spin-coat and wash the perovskite quantum dot thin film layer by layer on the basis of the electron transport layer to obtain a perovskite quantum dot light absorption layer. In this embodiment, the specific method is: dissolve the synthesized CsPbI3 quantum dots in n-octane with a concentration of 75 milligrams per milliliter, spin-coat for 15 seconds and 20 seconds at 1000 revolutions per minute and 2000 revolutions per minute respectively, drop an acetic acid methyl ester solution containing formamidinium thiocyanate with a concentration of 0.05 milligrams per milliliter onto the quantum dot thin film, keep it for 5 seconds, and then spin-dry at 2000 revolutions per minute. Repeat the process of spin-coating and washing 5 times to obtain a perovskite quantum dot light absorption layer with a thickness of about 400 nanometers.

[0051] Step 3, spin-coat the polymer PTAA on the perovskite quantum dot light absorption layer to form a hole transport layer. The specific method is: dissolve PTAA in toluene to prepare a solution with a concentration of 15 milligrams per milliliter, dope 5% by mass of tris(pentafluorophenyl)borane, and spin-coat for 40 seconds at a rotation speed of 3000 revolutions per minute to form a hole transport layer with a thickness of about 80 nanometers.

[0052] Step 4, vacuum thermally evaporate a metal electrode on the hole transport layer. The thicknesses of MoO x and Ag are 8 nanometers and 120 nanometers respectively to obtain an FAPbI3 perovskite quantum dot solar cell.

[0053] See the appendix Figure 6, which is the current density-voltage (J-V) curve of the perovskite quantum dot solar cell provided in this embodiment using CsPbI3 quantum dots as the light absorption layer and PTAA as the hole transport layer; under the standard test conditions of AM 1.5G, 100 mW / cm 2 , the short-circuit current density of the device measured is 16.29 mA / cm 2 , the open-circuit voltage is 1.248 V, the fill factor is 77.3%, and the photoelectric conversion efficiency is 15.72%.

[0054] Example 3

[0055] This embodiment provides a FAPbI3 perovskite quantum dot solar cell, the structure of which is as Figure 1 shown. The preparation of the battery includes the following steps: sequentially prepare an electron transport layer 2, a perovskite quantum dot light absorption layer 3, a hole transport layer 4, and a metal electrode 5 on a conductive glass substrate 1.

[0056] The specific steps are as follows:

[0057] Step 1, on a clean fluorine-doped tin oxide (abbreviated as FTO) conductive glass substrate, spin-coat an aqueous solution of tin oxide with a concentration of 2.67% at a speed of 3000 revolutions per minute, and then anneal at 160 °C for 30 minutes to obtain an electron transport layer with a thickness of about 30 nanometers;

[0058] Step 2, in an air atmosphere with a humidity of 10%, spin-coat and wash the perovskite quantum dot thin film layer by layer on the basis of the electron transport layer to obtain a perovskite quantum dot light absorption layer. In this embodiment, the specific method is: dissolve the synthesized FAPbI3 quantum dots in n-octane with a concentration of 75 mg per milliliter, spin-coat for 15 seconds and 20 seconds at 1000 revolutions per minute and 2000 revolutions per minute respectively, drop an acetic acid methyl ester solution containing formamidinium formate ionic liquid with a concentration of 0.1 mg per milliliter onto the quantum dot thin film, keep it for 5 seconds, and then spin-dry at 2000 revolutions per minute. Repeat the process of spin-coating and washing 3 times to obtain a perovskite quantum dot light absorption layer with a thickness of about 300 nanometers.

[0059] Step 3, spin-coat the polymer PTAA on the perovskite quantum dot light absorption layer to form a hole transport layer. The specific method is: dissolve PTAA in toluene to prepare a solution with a concentration of 15 mg per milliliter, dope 5% by mass of tris(pentafluorophenyl)borane, and spin-coat for 40 seconds at a rotation speed of 3000 revolutions per minute to form a hole transport layer with a thickness of about 80 nanometers.

[0060] Step 4, vacuum thermally evaporate a metal electrode on the hole transport layer. The thicknesses of MoO x and Ag are 8 nanometers and 120 nanometers respectively to obtain a FAPbI3 perovskite quantum dot solar cell.

[0061] See the appendix Figure 7 , which is the current density-voltage (J-V) curve of the perovskite quantum dot solar cell provided in this embodiment that uses FAPbI3 quantum dots as the light absorption layer and PTAA as the hole transport layer; under the standard test conditions of AM 1.5G, 100 mW / cm 2 , the short-circuit current density of the device measured is 17.18 mA / cm 2 , the open-circuit voltage is 1.134 V, the fill factor is 70.8%, and the photoelectric conversion efficiency is 13.80%.

[0062] Example 4

[0063] This embodiment provides an FAPbI3 perovskite quantum dot solar cell, the structure of which is as shown in Figure 1 . The preparation of the battery includes the following steps: sequentially prepare an electron transport layer 2, a perovskite quantum dot light absorption layer 3, a hole transport layer 4, and a metal electrode 5 on the conductive glass substrate 1.

[0064] The specific steps are as follows:

[0065] Step 1, on a clean indium-doped tin oxide (ITO for short) conductive glass substrate, spin-coat an aqueous solution of tin oxide with a concentration of 2.67% at a speed of 3000 revolutions per minute, and then anneal at 160 °C for 30 minutes to obtain an electron transport layer with a thickness of about 30 nanometers;

[0066] Step 2, in an air atmosphere with a humidity of 10%, spin-coat and clean the perovskite quantum dot thin film layer by layer on the basis of the electron transport layer to obtain a perovskite quantum dot light absorption layer. In this embodiment, the specific method is: dissolve the synthesized FAPbI3 quantum dots in n-octane with a concentration of 75 mg / ml, spin-coat for 15 seconds and 20 seconds at 1000 revolutions per minute and 2000 revolutions per minute respectively, drop an acetic acid methyl ester solution containing 1-hexyl-3-methylimidazolium iodide ionic liquid with a concentration of 0.1 mg / ml onto the quantum dot thin film, keep it for 5 seconds, and then spin-dry at 2000 revolutions per minute. Repeat the process of spin-coating and cleaning 3 times to obtain a perovskite quantum dot light absorption layer with a thickness of about 300 nanometers.

[0067] Step 3: Spin-coat Spiro-OMeTAD on the perovskite quantum dot light-absorbing layer to form a hole transport layer. The specific method is as follows: Spiro-OMeTAD is dissolved in chlorobenzene at a concentration of 70.3 mg / ml, and then 28.8 μl of 4-tert-butylpyridine, 17.5 μl of an acetonitrile solution of lithium bis(trifluoromethanesulfonyl)imide with a concentration of 520 mg / ml, and 10 μl of an acetonitrile solution of cobalt-based bis(trifluoromethanesulfonyl)imide salt with a concentration of 300 mg / ml are added; the above solution is spin-coated on the quantum dot film at a speed of 4000 revolutions per minute for 30 seconds to obtain a hole transport layer with a thickness of about 80 nm.

[0068] Step 4: Vacuum thermally evaporate metal electrodes on the hole transport layer. The thicknesses of MoO x and Ag are 8 nm and 120 nm respectively to obtain the FAPbI3 perovskite quantum dot solar cell.

[0069] See Appendix Figure 8 , which is the current density-voltage (J-V) curve graph of the perovskite quantum dot solar cell provided in this embodiment using FAPbI3 quantum dots as the light absorption layer and PTAA as the hole transport layer; under the standard test conditions of AM 1.5G, 100 mW / cm 2 , the short-circuit current density of the device measured is 16.23 mA / cm 2 , the open-circuit voltage is 1.134 V, the fill factor is 72.6%, and the photoelectric conversion efficiency is 13.36%.

Claims

1. A perovskite quantum dot solar cell, characterized in that: It includes a conductive glass substrate, an electron transport layer, a quantum dot light absorption layer, a hole transport layer, and a metal electrode: The quantum dot light absorption layer is obtained by treating a perovskite quantum dot film with a structure of ABX3 with a mixed solution of formamidinium thiocyanate and a certain acid ester, and synergistically realizing ligand exchange and surface defect passivation. Among them, A is formamidinium or Cs + ion, B is Pb 2+ or Sn 2+ ion, and X is I - or Br - ion; The certain acid ester solution includes methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, or ethyl butyrate.

2. The perovskite quantum dot solar cell according to claim 1, wherein : The size of the perovskite quantum dots in the ABX3 structure of the quantum dot light absorption layer is 5 to 20 nanometers, and the thickness of the perovskite quantum dot light absorption layer is 100 to 800 nanometers.

3. A perovskite quantum dot solar cell according to claim 1, characterized in that: The electron transport layer is one of PCBM, TiO2, SnO2 or ZnO thin films, and the thickness of the electron transport layer is 10 to 200 nanometers.

4. A perovskite quantum dot solar cell according to claim 1, characterized in that: The hole transport layer is one of PTAA, PTB7, Spiro-OMTAD, PTBT-Th, P3HT or PBDB-T, and the thickness of the hole transport layer is 10 to 200 nanometers.

5. A perovskite quantum dot solar cell according to claim 1, characterized in that: The metal electrode is one of MoO x / Ag, MoO x / Al or Au, and the thickness is 20 to 200 nanometers.

6. A preparation method of a perovskite quantum dot solar cell, characterized in that It includes the following steps: (1) Spin-coat an electron transport material on a conductive glass substrate to obtain an electron transport layer; (2) Prepare a perovskite quantum dot light absorption layer (a) The perovskite quantum dot solution is deposited on the electron transport layer by spin coating to obtain a perovskite quantum dot film with a structure of ABX3, where A is formamidine or Cs + ion, B is Pb 2+ or Sn 2+ ion, and X is I - or Br - ion; (b) Drop a mixed solution of formamidinium thiocyanate and a certain acid ester on the quantum dot film, keep it for 2 to 10 seconds, spin-dry it, and perform ligand exchange and surface defect passivation treatment; the certain acid ester solution includes methyl formate, ethyl formate, methyl acetate, ethyl acetate, ethyl propionate, methyl butyrate or ethyl butyrate; in the said mixed solution, the concentration of formamidinium thiocyanate is 0.001 to 2 mg / ml; (c) Repeat steps (a) to (b) 2 to 10 times to obtain a perovskite quantum dot light absorption layer; (3) Prepare a hole transport layer on the light absorption layer; (4) Evaporate a metal electrode on the hole transport layer to obtain a perovskite quantum dot solar cell.

7. The preparation method of a perovskite quantum dot solar cell according to claim 6, characterized in that: The thickness of the perovskite quantum dot light absorption layer is 100 to 800 nanometers.

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