Lead halide perovskite quantum dot, conductive ink, preparation method and application

Abstract

The invention provides a lead halide perovskite quantum dot, conductive ink, a preparation method and application. An organic acid / alkali ligand is used as an initiator, the surface of the quantum dot is treated through liquid-phase ligand exchange, an insulating ligand on the surface of the quantum dot is effectively removed under the condition of keeping a crystal structure unchanged, the high-dispersion and high-stability quantum dot and conductive ink are prepared, one-step spin coating or blade coating film forming can be achieved, and a complex layer-by-layer deposition process is not needed. The method has the characteristics of simplicity in operation and easiness in regulation and control. According to the lead halide perovskite quantum dot provided by the invention, the acid-base environment in the quantum dot solution is regulated and controlled, the dynamic balance of the surface ligand of the quantum dot is broken, the separation of the quantum dot and the surface ligand is realized, the perovskite quantum dot ink with low ligand density and high conductivity is prepared, the efficiency of the prepared photoelectric device reaches 16.04%, and the photoelectric device has good application prospects. The perovskite quantum dot solar cell prepared by the method has the advantages that the device efficiency reaches 16.57%, and the method has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of functional materials and device applications, and particularly relates to a lead halide perovskite quantum dot, a conductive ink material, a preparation method and an application thereof. Background Art

[0002] As a new generation of nano-semiconductor materials, lead halide perovskite quantum dot materials have excellent optoelectronic properties such as high absorption coefficient, high defect tolerance, and high fluorescence quantum yield, and show great application potential in optoelectronic fields such as solar cells, light-emitting diodes, lasers, and detectors. In recent years, the device efficiency in the field of solar cells has reached more than 18% (see the literature: Aqoma, H. et al. Alkyl ammonium iodide-based ligand exchange strategy for high-efficiency organic-cation perovskite quantum dot solar cells. Nat Energy 9, 324–332 (2024).).

[0003] Currently, perovskite quantum dots used for high-performance solar cells are usually synthesized based on the thermal injection method, in which oleic acid and oleylamine are used as long-chain surface ligands to ensure stability and good dispersion in non-polar solutions (see the literature: Amrita, D. et al. State of the Art and Prospects for Halide Perovskite Nanocrystals. ACS Nano 15, 10775–10981 (2021).). However, the charge conductivity of long-chain insulating ligands is poor, and the prepared perovskite quantum dots are not suitable for direct application in solar cells. Therefore, the layer-by-layer deposition method (LbL) can obtain a conductive film with sufficient thickness by treating the long-chain ligands on the quantum dot film layer by layer, and at the same time passivate the surface of perovskite quantum dots with short-chain conductive ligands (see the literature: Abhishek, S. et al. Quantum dot–induced phase stabilization of α-CsPbI 3Perovskite for high-efficiency photovoltaics. Science 354, 92-95 (2016).). However, the LbL process requires repeating multiple layers to obtain a sufficient active layer thickness, which is a time-consuming way for large-scale applications. And during the processing of each layer, the dynamic ligand exchange process causes severe shrinkage of the perovskite quantum dot film, affecting the overall quality of the film (see the literature: Qian, Z., et al. Colloidal Quantum Dot Solar Cells: Progressive Deposition Techniques and Future Prospects on Large-Area Fabrication. Adv. Mater. 34, 2107888 (2022).).

[0004] Therefore, adopting appropriate surface chemical regulation means to achieve in-situ ligand exchange of perovskite quantum dots in the liquid phase, preparing perovskite quantum dot conductive ink, and developing new film-forming processes compatible with large-scale blade coating and inkjet printing processes are one of the important methods to solve the above key problems, which has important practical significance for the further application of perovskite quantum dot semiconductor materials in the optoelectronic field. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention introduces a functionalized organic short-chain acid / base ligand initiator for in-situ ligand exchange in the liquid phase environment of perovskite quantum dots, providing a perovskite quantum dot, conductive ink with high dispersion and high stability performance and a preparation method thereof, which can realize one-step spin coating or blade coating film formation without the application of a complex layer-by-layer deposition process, effectively improving the device efficiency.

[0006] The technical solution to achieve the object of the present invention is to provide a preparation method of perovskite quantum dots and a perovskite quantum dot obtained according to the preparation method; the preparation method includes the following steps: (1) Disperse ABX perovskite nanocrystals with oleic acid and oleylamine as surface ligands in a solvent to obtain a solution with a concentration of 20-30 mg / mL; the solvent includes an alkane non-polar solvent with a dielectric constant less than 2.1 at 20 °C; the ABX 3 , wherein A is a cation, including cesium Cs 3 , formamidine CH(NH + ) 2 2 + , methylamine CH 3 NH 3 + , or any mixture thereof, and B is the cation lead Pb​2+ where X is anionic iodine I - ; (2) In the solution prepared in step (1), an organic acid or base ligand reactant is added in a volume ratio of 0.001 to 0.1 to obtain a ligand exchange reaction solution, and the reaction is carried out for 10 seconds to 10 minutes; the organic acid ligand reactant includes alkyl acids and short-chain organic acids such as 2-phenylpropanoic acid; the organic base ligand reactant used includes alkylamines, 2-phenylpropylamine, and short-chain organic amines such as phenethylamine; (3) Through separation and drying treatments, a perovskite quantum dot is obtained.

[0007] In step (2), the pH value range of the ligand exchange reaction solution with the organic acid ligand reactant added is 7 to 0; the pH value range of the ligand exchange reaction solution with the organic base ligand reactant added is 7 to 14.

[0008] The alkanes include n-hexane, n-pentane, n-octane, and cyclohexane.

[0009] The separation treatment includes centrifugation at 500 to 1000 revolutions per minute.

[0010] The technical solution of the present invention also provides a preparation method of a perovskite quantum dot conductive ink, and a perovskite quantum dot conductive ink obtained according to this preparation method: the perovskite quantum dots prepared according to the technical solution of the present invention are dispersed in a solvent, and the solvent includes non-polar solvents such as toluene, chlorobenzene, and chloroform with a dielectric constant of 2.1 to 5.0 to obtain a perovskite quantum dot conductive ink.

[0011] The application of the perovskite quantum dot conductive ink of the present invention uses a one-step spin coating, spraying, scraping, or inkjet printing process to form a film and is used as a photoactive layer of an optoelectronic device.

[0012] The optoelectronic devices include solar cells and photodetectors.

[0013] The solar cell includes a conductive glass substrate, an electron transport layer, a perovskite quantum dot light absorption layer, a hole transport layer, and a metal electrode, and its preparation method includes the following steps: (1) Prepare an electron transport layer on the conductive glass substrate; (2) Use a one-step spin coating or scraping process to apply the perovskite quantum dot conductive ink with a concentration of 100 to 500 mg / mL on the electron transport layer to prepare a perovskite quantum dot thin film with a thickness of 50 to 800 nanometers to obtain a perovskite light absorption layer; (3) Use a spin coating method to prepare an organic hole transport layer on the light absorption layer to obtain a hole transport layer with a thickness of 30 to 80 nanometers; (4) Use a vacuum coating process to deposit a metal electrode on the hole transport layer to obtain a perovskite quantum dot solar cell.

[0014] The principle of the present invention is as follows: the change in pH value in the perovskite quantum dot solution triggers the protonation / deprotonation reaction of the surface oleic acid / octylamine ligands, and the introduced organic acid / base ion ligands can be in-situ combined on the surface of the quantum dots. After ligand exchange for a period of time (10 seconds to 10 minutes), the ligands on the surface of the perovskite quantum dots are exchanged from long-chain ligands to short-chain ligands, resulting in a decrease in the dispersibility in non-polar solvents, thereby inducing aggregation and sedimentation, and producing perovskite quantum dots coated with low ligand density and short-chain ligands.

[0015] Compared with the prior art, the technical solution of the present invention has the following outstanding features: 1. By changing the liquid-phase acid-base environment of the perovskite quantum dots, the present invention breaks the dynamic equilibrium of the ligands on the surface of the quantum dots, realizes the removal and replacement of the surface ligands, and develops a new process for ligand exchange on the surface of perovskite quantum dots. The introduced acid-base initiator can protonate / deprotonate the surface oleic acid / octylamine ligands, and at the same time, the formed short-chain acid / base ion ligands bind to the surface of the quantum dots to passivate the surface defects, improve the conductivity and stability of the perovskite quantum dots, and thus realize the preparation of high-performance perovskite quantum dot conductive inks.

[0016] 2. The perovskite quantum dot ink provided by the present invention is compatible with one-step film-forming processes such as spin coating, spraying, and blade coating, solves the cumbersome layer-by-layer deposition process and difficult-to-control solid-phase ligand exchange in the preparation process of traditional perovskite quantum dot devices, thereby simplifies the device preparation process and is conducive to the commercial promotion of perovskite quantum dots.

[0017] 3. The present invention selects perovskite quantum dots with near-infrared absorption, prepares high-efficiency perovskite quantum dot solar cells, and obtains hybrid FAPbI prepared by one-step spin coating 3 The photoelectric conversion efficiency of the solar cell reaches 16.57%, the photoelectric conversion efficiency of the hybrid MAPbI solar cell prepared by one-step spin coating 3 reaches 14.71% (the current efficiency of the solar cell prepared with this material is 13.34%), and the photoelectric conversion efficiency of the all-inorganic CsPbI solar cell prepared by one-step spin coating 3 reaches 16.38% (the current record is 14.92%), which proves the feasibility and application prospects of the materials and technical means in optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a comparative transmission electron microscope (TEM) image of perovskite quantum dots provided in Example 1 of the present invention; In the figure, Figure a is the morphology of standard perovskite quantum dots without liquid-phase ligand exchange, and Figure b is the morphology of perovskite quantum dots after liquid-phase ligand exchange; Figure 2 This is the surface ligand situation of the perovskite quantum dot ink prepared in Example 2 of the present invention; Figure a shows the pH values corresponding to the perovskite quantum dot solutions with different ratios of acid initiators, and Figure b shows the infrared spectra (FTIR) of the perovskite quantum dots corresponding to different pH values; Figure 3 This is the surface ligand situation of the perovskite quantum dot ink prepared in Example 3 of the present invention; Figure a shows the pH values corresponding to the perovskite quantum dot solutions with different ratios of base initiators, and Figure b shows the infrared spectra (FTIR) of the perovskite quantum dots corresponding to different pH values; Figure 4 This is a schematic diagram of the device structure of the perovskite quantum dot solar cell provided in the embodiment of the present invention; In the figure, 1. Transparent conductive glass; 2. Electron transport layer; 3. Light absorption layer; 4. Hole transport layer; 5. Metal electrode; Figure 5 This is the hybrid FAPbI prepared in Example 5 of the present invention 3 Voltage-current density curve of the perovskite quantum dot solar cell; Figure 6 This is the all-inorganic CsPbI prepared in Example 6 of the present invention 3 Voltage-current density curve of the perovskite quantum dot solar cell; Figure 7 This is the hybrid MAPbI prepared in Example 7 of the present invention 3 Voltage-current density curve of the perovskite quantum dot solar cell; Figure 8 This is a photo of the perovskite quantum dot film with a spin-coated film area of 9×9 square centimeters prepared in Example 8 of the present invention; Figures 9 to 11 These are the voltage-current density curves of the perovskite quantum dot solar cell devices with spin-coated films prepared in Example 8 of the present invention, respectively. Detailed implementation manners

[0019] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments. Example 1

[0020] This example provides a hybrid FAPbI 3 Perovskite quantum dots and conductive ink, and the specific steps of the preparation method are as follows: Step 1: Disperse the hybrid FAPbI 3 Perovskite quantum dots synthesized by the thermal injection method in a n-hexane solution for standby; Step 2: Using 2-phenylpropionic acid as an acid ligand initiator, add 1000 μL of 2-phenylpropionic acid (1:0.05) dropwise to 20 mL of the quantum dot solution, and react for about 10 seconds. The quantum dots start to aggregate and induce sedimentation.

[0021] Step 3: Separate the sedimented quantum dots by a centrifuge at a speed of 1000 revolutions per minute for 2 minutes, pour out the supernatant, and obtain hybrid FAPbI 3 perovskite quantum dots, retain the obtained solid and weigh it; Step 4: Select toluene solvent to disperse the obtained hybrid FAPbI 3 perovskite quantum dots to obtain perovskite quantum dot conductive ink.

[0022] See the appendix Figure 1 , in the figure, Figure a is the morphology of standard hybrid FAPbI 3 perovskite quantum dots without acid-base balance-induced ligand exchange, and Figure b is the morphology of perovskite quantum dots after acid-base balance-induced ligand exchange. It can be clearly found by comparison that the perovskite quantum dots after ligand exchange have an effect of aggregation and self-assembly. Example 2

[0023] This example provides a hybrid FAPbI 3 perovskite quantum dot and conductive ink, and the specific steps of the preparation method are as follows: Step 1: Disperse the hybrid FAPbI 3 perovskite quantum dots synthesized by the thermal injection method in a n-hexane solution for standby; Step 2: Using acetic acid as an acid ligand initiator, add 2000 μL (1:0.1), 1000 μL (1:0.05), 400 μL (1:0.02), 100 μL (1:0.005) of acetic acid dropwise to 20 mL of the quantum dot solution, and react for about 10 seconds. The quantum dots start to aggregate and induce sedimentation.

[0024] Step 3: Separate the sedimented quantum dots by a centrifuge at a speed of 1000 revolutions per minute for 2 minutes, pour out the supernatant, retain the obtained solid and weigh it; Step 4: Select toluene solvent to disperse the obtained hybrid FAPbI 3 perovskite quantum dots to obtain perovskite quantum dot conductive ink.

[0025] See the appendix Figure 2 , Figure a is the pH value corresponding to the perovskite quantum dot solution with different ratios of acid initiator, and Figure b is the FTIR of perovskite quantum dots corresponding to different pH values. Example 3

[0026] This example provides a hybrid FAPbI3 Perovskite quantum dots and conductive ink, the specific steps of the preparation method are as follows: Step 1: Disperse the hybrid FAPbI perovskite quantum dots synthesized by the hot injection method in n - hexane solution for standby; 3 Perovskite quantum dots are dispersed in n - hexane solution for standby; Step 2: Use 2 - phenylpropylamine as the base ligand initiator, and add 100 μL (1:0.005) of 2 - phenylpropylamine dropwise to 20 mL of the quantum dot solution, react for about 10 seconds, and the quantum dots start to aggregate and induce sedimentation.

[0027] Step 3: Separate the sedimented quantum dots by a centrifuge, centrifuge at a speed of 1000 revolutions per minute for 2 minutes, pour out the supernatant, retain the obtained solid and weigh it; Step 4: Select toluene solvent to disperse the obtained hybrid FAPbI perovskite quantum dots to obtain perovskite quantum dot ink. 3 Perovskite quantum dots are selected to use toluene solvent to disperse the quantum dots to obtain perovskite quantum dot ink.

[0028] See Appendix Figure 3 , Figure a shows the pH values of the perovskite quantum dot solutions corresponding to different ratios of amine initiators, and Figure b shows the FTIR of the perovskite quantum dots corresponding to different pH values. Example 4

[0029] This example provides a hybrid MAPbI perovskite quantum dot and conductive ink, and the specific steps of its preparation method are as follows: 3 Perovskite quantum dots and conductive ink, the specific steps of the preparation method are as follows: Step 1: Disperse the hybrid MAPbI perovskite quantum dots synthesized by the hot injection method in n - hexane solution for standby; 3 Perovskite quantum dots are dispersed in n - hexane solution for standby; Step 2: Use 2 - phenylpropionic acid as the acid ligand initiator, and add 1000 μL of 2 - phenylpropionic acid (1:0.05) dropwise to 20 mL of the quantum dot solution, react for about 10 seconds, and the quantum dots start to aggregate and induce sedimentation.

[0030] Step 3: Separate the sedimented quantum dots by a centrifuge, centrifuge at a speed of 1000 revolutions per minute for 2 minutes, pour out the supernatant, retain the obtained solid and weigh it; Step 4: Select toluene solvent to disperse the obtained hybrid MAPbI perovskite quantum dots and obtain perovskite quantum dot conductive ink. 3 Perovskite quantum dots are selected to use toluene solvent to disperse the quantum dots and obtain perovskite quantum dot conductive ink. Example 5

[0031] This example provides a fully inorganic CsPbI perovskite quantum dot and conductive ink, and the specific steps of its preparation method are as follows: 3 Perovskite quantum dots and conductive ink, the specific steps of the preparation method are as follows: Step 1: Disperse the CsPbI perovskite quantum dots synthesized by the hot injection method in n - hexane solution for standby; 3 Perovskite quantum dots are dispersed in n - hexane solution for standby; Step 2: Using 2-phenylpropionic acid as an acid ligand initiator, add 100 μL of 2-phenylpropionic acid dropwise to 20 mL of the quantum dot solution, and react for about 10 seconds. The quantum dots start to aggregate and induce sedimentation. Step 3: Separate the sedimented quantum dots by a centrifuge at a rotation speed of 1000 revolutions per minute for 2 minutes, pour out the supernatant, retain the obtained solid and weigh it. Step 4: Select a solvent with a relatively high dielectric constant such as toluene to disperse the obtained CsPbI 3 perovskite quantum dots to obtain perovskite quantum dot conductive ink. Example 6

[0032] This example provides a method for preparing a hybrid FAPbI 3 perovskite quantum dot solar cell, achieving a photoelectric conversion efficiency of 16.57%. The device structure is shown in the appendix Figure 4 as shown. 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.

[0033] The preparation method of the battery is as follows: Step 1: Ultrasonically wash the fluorine-doped tin oxide (abbreviated as FTO) conductive glass with dishwashing detergent water, acetone, isopropyl alcohol, and acetone in sequence; prepare a dense TiO 2 film with a thickness of about 40 nm on the cleaned substrate by chemical bath deposition to obtain the electron transport layer 2, and anneal it at 200 °C for 30 minutes. Step 2: In a dry air atmosphere, adopt the one-step spin-coating film formation method to spin-coat the 200 mg / mL FAPbI 3 solution (the ink prepared in Example 1) on the substrate at 800 revolutions per minute and 2000 revolutions per minute for 15 seconds and 20 seconds respectively, and a perovskite quantum dot film 3 with a thickness of about 300 nm is obtained.

[0034] Step 3: Spin-coat the polymer PTAA on the light absorption layer 3 to prepare the hole transport layer 4. Dissolve PTAA in toluene to prepare a solution with a concentration of 15 mg / mL, and spin-coat it at a rotation speed of 3000 revolutions per minute for 40 seconds to form a hole transport layer with a thickness of about 70 nm.

[0035] Step 4: Vacuum thermally evaporate the metal electrode 5 on the hole transport layer 4. The thicknesses of MoO X , Ag are 8 nm and 120 nm respectively to obtain a complete FAPbI 3 perovskite quantum dot solar cell.

[0036] See the appendix Figure 5, which is provided in this embodiment, selects hybrid FAPbI 3 perovskite quantum dots as the light-absorbing layer, utilizes solution-phase ligand exchange, and adopts a one-step spin-coating film-forming process to prepare the current density-voltage (J-V) curve of a perovskite solar cell; under the standard test conditions of AM 1.5 and 100 mV / cm 2 , the short-circuit current density of the device measured is 20.894 mA / cm 2 , the open-circuit voltage is 1.117 V, the fill factor is 0.710, and the photoelectric conversion efficiency is 16.570%. Example 7

[0037] This embodiment provides a hybrid MAPbI 3 perovskite quantum dot solar cell, which achieves a photoelectric conversion efficiency of 14.71%. The device structure is as Figure 4 shown. The specific steps of its preparation method are as follows: Step 1: Ultrasonically wash the fluorine-doped tin oxide (abbreviated as FTO) conductive glass with dishwashing liquid water, acetone, isopropyl alcohol, and acetone in sequence; prepare a dense TiO film with a thickness of about 40 nanometers on the cleaned substrate through chemical bath deposition 2 , to obtain the electron transport layer 2, and anneal it at 200 °C for 30 minutes; Step 2: In a dry air atmosphere, adopt a one-step spin-coating film-forming method to spin-coat the 200 mg / ml MAPbI 3 solution (the ink prepared in Example 4) on the substrate at 800 revolutions per minute and 2000 revolutions per minute for 15 seconds and 20 seconds respectively, to obtain a perovskite quantum dot film with high electron coupling and a thickness of about 300 nanometers.

[0038] Step 3: Spin-coat the polymer PTAA on the light-absorbing layer 3 to prepare the hole transport layer 4. Dissolve PTAA in toluene to prepare a solution with a concentration of 15 mg / ml, and spin-coat it at a speed of 3000 revolutions per minute for 40 seconds to form a hole transport layer with a thickness of about 70 nanometers.

[0039] Step 4: Vacuum thermally evaporate the metal electrode 5 on the hole transport layer 4. The thicknesses of MoO X and Ag are 8 nanometers and 120 nanometers respectively, to obtain a complete MAPbI 3 perovskite quantum dot solar cell.

[0040] See the appendix Figure 6 , which is provided in this embodiment, selects hybrid MAPbI 3Current density-voltage (J-V) curve of a perovskite solar cell using perovskite quantum dots as the light-absorbing layer, prepared by solution-phase ligand exchange and a one-step spin-coating film-forming process; under standard test conditions of AM 1.5, 100 mV / cm 2 The short-circuit current density of the device measured under the standard test conditions is 17.734 mA / cm 2 , the open-circuit voltage is 1.165 V, the fill factor is 0.712, and the photoelectric conversion efficiency is 14.710% (the record efficiency of the solar cell prepared with this material, currently the record is 13.34%). Example 8

[0041] This example provides a fully inorganic CsPbI 3 perovskite quantum dot solar cell, achieving a photoelectric conversion efficiency of 16.38%. The device structure is as Figure 4 shown. The specific steps of its preparation method are as follows: Step 1: Ultrasonically wash the fluorine-doped tin oxide (abbreviated as FTO) conductive glass with dishwashing detergent water, acetone, isopropyl alcohol, and acetone in sequence; prepare a dense TiO 2 film with a thickness of about 40 nanometers on the cleaned substrate by chemical bath deposition to obtain the electron transport layer 2, and anneal it at 200 °C for 30 minutes; Step 2: In a dry air atmosphere, adopt a one-step spin-coating film-forming method to spin-coat the 200 mg / mL CsPbI 3 solution (the ink prepared in Example 5) on the substrate at 800 revolutions per minute and 2000 revolutions per minute for 15 seconds and 20 seconds respectively, and treat the film with a GASCN solution of methyl acetate for 5 seconds to obtain a perovskite film with high electron coupling and a thickness of about 300 nanometers.

[0042] Step 3: Spin-coat the polymer PTAA on the light-absorbing layer 3 to prepare the hole transport layer 4. Dissolve PTAA in toluene to prepare a solution with a concentration of 15 mg / mL, and spin-coat it at a rotation speed of 3000 revolutions per minute for 40 seconds to form a hole transport layer with a thickness of about 70 nanometers.

[0043] Step 4: Vacuum thermally evaporate the metal electrode 5, MoO X , Ag with thicknesses of 8 nanometers and 120 nanometers respectively on the hole transport layer 4 to obtain a complete CsPbI 3 perovskite quantum dot solar cell.

[0044] See the appendix Figure 7 , which is provided in this example. Select the fully inorganic CsPbI 3Current density-voltage (J-V) curve of a perovskite solar cell using perovskite quantum dots as the light-absorbing layer, prepared by solution-phase ligand exchange and a one-step spin-coating film-forming process; under standard test conditions of AM 1.5, 100 mV / cm 2 , the short-circuit current density of the device measured was 17.728 mA / cm 2 , the open-circuit voltage was 1.264 V, the fill factor was 0.731, and the photoelectric conversion efficiency was 16.380% (the recorded efficiency of the cell prepared by one-step spin-coating this material, currently the record is 14.92%). Example 9

[0045] This example provides a method for preparing a hybrid FAPbI 3 perovskite quantum dot solar cell and achieved a photoelectric conversion efficiency of 16.04%. The device structure is as Figure 4 shown. The specific steps of its preparation method are as follows: Step 1: Ultrasonically wash the fluorine-doped tin oxide (abbreviated as FTO) conductive glass with dishwashing detergent water, acetone, isopropyl alcohol, and acetone in sequence; prepare a dense TiO 2 film with a thickness of about 40 nanometers on the cleaned substrate by chemical bath deposition to obtain the electron transport layer 2, and anneal it at 200 °C for 30 minutes; Step 2: In a dry air atmosphere, adopt the blade coating film-forming method to coat the 800 mg / mL FAPbI 3 solution (the ink prepared in Example 1) on the 9×9 square centimeter FTO / TiO 2 substrate at a speed of 10 mm per second for 10 minutes, thus obtaining a perovskite quantum dot thin film layer 3 with high electron coupling and a thickness of about 300 nanometers.

[0046] Step 3: Spin-coat the polymer PTAA on the light-absorbing layer 3 to prepare the hole transport layer 4. Dissolve PTAA in toluene to prepare a solution with a concentration of 15 mg / mL, and spin-coat it at a rotation speed of 3000 revolutions per minute for 40 seconds to form a hole transport layer with a thickness of about 70 nanometers.

[0047] Step 4: Vacuum thermally evaporate the metal electrode 5, MoO X , Ag with thicknesses of 8 nanometers and 120 nanometers respectively on the hole transport layer 4 to obtain a complete FAPbI 3 perovskite quantum dot solar cell.

[0048] See the appendix Figure 8 , which is a photo of the 9*9 square centimeter perovskite quantum dot thin film prepared by blade coating.

[0049] See the appendix Figure 9 , which is the appendix provided in this exampleFigure 8 Current density-voltage (J-V) curve of a perovskite solar cell prepared from the No. 7 quantum dot thin film selected from 2 Under the standard test conditions of AM 1.5, 100 mV / cm 2 , the short-circuit current density of the device was measured to be 20.615 mA / cm

[0050] See the appendix Figure 10 , which is the appendix provided in this embodiment Figure 8 Current density-voltage (J-V) curve of a perovskite solar cell prepared from the No. 17 quantum dot thin film selected from 2 Under the standard test conditions of AM 1.5, 100 mV / cm 2 , the short-circuit current density of the device was measured to be 20.373 mA / cm

[0051] See the appendix Figure 11 , which is the appendix provided in this embodiment Figure 8 Current density-voltage (J-V) curve of a perovskite solar cell prepared from the No. 39 quantum dot thin film selected from 2 Under the standard test conditions of AM 1.5, 100 mV / cm 2 , the short-circuit current density of the device was measured to be 20.023 mA / cm , the open-circuit voltage was 1.113 V, the fill factor was 0.713, and the photoelectric conversion efficiency was 15.890%.

Claims

1. A method for preparing perovskite quantum dots, characterized in that The steps include: (1) dispersing ABX3 perovskite nanocrystals whose surface ligands are oleic acid and oleylamine in a solvent to obtain a solution with a concentration of 20 to 30 mg / mL; the solvent comprises an alkane non-polar solvent having a dielectric constant of less than 2.1 at 20°C; the ABX3, wherein A is a cation selected from cesium Cs + 、Formamidine CH(NH2)2 + , methylamine CH3NH3 + , or any combination thereof, B is cation lead Pb 2+ , X is an iodine anion I - ; (2) adding an organic acid or base ligand reactant to the solution prepared in step (1) at a volume ratio of 0.001 to 0.1 to obtain a ligand exchange reaction solution, and reacting for 10 seconds to 10 minutes; the organic acid ligand reactant is selected from alkyl acid and 2-phenylpropionic acid short-chain organic acid; the organic base ligand reactant is selected from alkylamine, 2-phenylpropylamine, phenylethylamine short-chain organic amine; (3) After separation and drying, a perovskite quantum dot is obtained.

2. The method for preparing perovskite quantum dots according to claim 1, characterized in that: In step (2), the pH value of the ligand exchange reaction liquid to which an organic acid ligand reactant is added is in the range of 7 to 0; the pH value of the ligand exchange reaction liquid to which an organic base ligand reactant is added is in the range of 7 to 14.

3. The method for preparing perovskite quantum dots according to claim 1, characterized in that: The alkane is n-hexane, n-pentane, n-octane or cyclohexane.

4. The method for preparing perovskite quantum dots according to claim 1, characterized in that: The separation process includes centrifugal treatment at 500 to 1000 rpm.

5. A perovskite quantum dot obtained by the preparation method according to claim 1.

6. A method for preparing perovskite quantum dot conductive ink, characterized in that: The perovskite quantum dots described in claim 5 are dispersed in a solvent, wherein the solvent includes toluene, chlorobenzene, chloroform and other non-polar solvents with a dielectric constant of 2.1 to 5.0, to obtain perovskite quantum dot conductive ink.

7. A perovskite quantum dot conductive ink obtained by the preparation method according to claim 5.

8. An application of the perovskite quantum dot conductive ink as claimed in claim 7, characterized in that: The film is formed by a one-step spin coating, spray coating, blade coating, and inkjet printing process and is used as a photoactive layer of an optoelectronic device.

9. The use of a perovskite quantum dot conductive ink according to claim 8, characterized in that: The photoelectric device comprises a solar cell and a photoelectric detector.

10. The use of a perovskite quantum dot conductive ink according to claim 9, characterized in that: The solar cell comprises a conductive glass substrate, an electron transport layer, a perovskite quantum dot light absorption layer, a hole transport layer and a metal electrode, and the preparation method thereof comprises the following steps: (1) Preparing an electron transport layer on a conductive glass substrate; (2) applying a perovskite quantum dot conductive ink having a concentration of 100 to 500 mg / mL on the electron transport layer by a one-step spin coating or blade coating process to prepare a perovskite quantum dot film having a thickness of 50 to 800 nanometers to obtain a perovskite light absorbing layer; (3) preparing an organic hole transport layer on the light absorbing layer by spin coating to obtain a hole transport layer with a thickness of 30 to 80 nanometers; (4) A metal electrode is deposited on the hole transport layer using a vacuum coating process to obtain a perovskite quantum dot solar cell.

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