Formamidino perovskite solar cell with long-term operation stability and preparation method of formamidino perovskite solar cell

Abstract

The invention belongs to the technical field of photoelectric materials, and particularly relates to a formamidino perovskite solar cell with long-term operation stability and a preparation method of the formamidino perovskite solar cell. The invention firstly provides a novel formamidino perovskite solar cell, a perovskite absorption layer of the cell is a formamidino perovskite absorption layer, and the formamidino perovskite absorption layer comprises a lead iodide film made of a three-dimensional compound with at least three carbonyl functional groups and lead iodide. The novel formamidino perovskite solar cell provided by the invention is stable in optical active phase and has long-term operation stability.

Description

[0001] Divisional application This application is a divisional application of a Chinese patent application with the application number 2024100785867, the application date of January 18, 2024, and the invention title of "A Method for Improving the Stability of Perovskite Solar Cells by Carbonyl Compounds". Technical field

[0002] The present invention belongs to the technical field of optoelectronic materials, and specifically relates to a formamidinium perovskite solar cell with long-term operating stability and a preparation method thereof. Background art

[0003] Solar energy has always been one of the most promising, reliable and renewable energy sources among various alternative energy sources. Since the discovery of the photovoltaic (PV) effect, solar cell technology has been continuously developed and evolved, making solar energy widely adopted as a viable renewable resource. Perovskite solar cells based on metal-organic halide light-absorbing materials are a new type of solar cell, and their photoelectric conversion efficiency has increased from 3.8% in 2009 to more than 20% currently. However, perovskite is prone to phase transition at room temperature and is liable to generate non-photoactive phases, thereby causing a decrease in the photoelectric power conversion efficiency. Therefore, it is of great significance to prepare perovskite solar cells with long-term operating stability.

[0004] Chinese Patent with the publication number CN111223994A and the invention title of "A Fully Printed Mesoscopic Perovskite Solar Cell Using Carbonyl Small Molecules as Additives and a Preparation Method Thereof" discloses introducing ethylene carbonate with a molar ratio concentration of 6% as a passivator and crosslinker for perovskite crystallization in the perovskite precursor solution. The open-circuit voltage of the finally prepared perovskite solar cell is 0.92V, and the photoelectric conversion efficiency is 15.44%. However, the photoelectric conversion efficiency of existing perovskite solar cells has reached more than 20%. Therefore, the photoelectric conversion efficiency of the perovskite solar cells prepared by this patent strategy is not very high.

[0005] In summary, it is necessary to propose new methods and strategies to alleviate the deficiencies of the existing technology. Summary of the invention

[0006] The purpose of the present invention is to provide a formamidinium perovskite solar cell with long-term operating stability and a preparation method thereof, which partially solves or alleviates the above deficiencies in the existing technology. The present invention specifically adopts the following technical solutions.

[0007] On the one hand, the present invention aims to provide a formamidinium perovskite solar cell with long-term operating stability.

[0008] A formamidinium perovskite solar cell with long-term operating stability, the formamidinium perovskite solar cell comprising, from bottom to top, a conductive glass layer, an electron transport layer, a perovskite absorption layer, a hole transport layer, and an electrode group layer; the perovskite absorption layer is a formamidinium perovskite absorption layer with a thickness ranging from 700 to 800 nm; the formamidinium perovskite absorption layer includes a lead iodide thin film made of a three-dimensional compound having at least 3 carbonyl functional groups and lead iodide; the three-dimensional compound having at least 3 carbonyl functional groups is 4,4',4''-aminotribenzaldehyde; the molar concentration ratio of 4,4',4''-aminotribenzaldehyde to lead iodide is 0.3 to 5 mM: 1 to 1.6 M.

[0009] Further, the molar concentration ratio of 4,4',4''-aminotribenzaldehyde to lead iodide includes 0.3 mM: 1 to 1.6 M, 0.6 mM: 1 to 1.6 M, 1 mM: 1 to 1.6 M, 2 mM: 1 to 1.6 M, 3 mM: 1 to 1.6 M, 4 mM: 1 to 1.6 M, or 5 mM: 1 to 1.6 M.

[0010] As a preferred embodiment, the molar concentration ratio of 4,4',4''-aminotribenzaldehyde to lead iodide is 1 mM: 1 to 1.6 M.

[0011] Further, the formamidinium perovskite absorption layer further includes a mixed salt solution made of a mixed solution of 0.02 to 0.06 M methylammonium iodide, 0.10 to 0.30 M methylammonium chloride, and 0.4 to 0.7 M formamidinium hydroiodide.

[0012] Another aspect of the present invention is to provide a method for preparing a formamidinium perovskite solar cell with long-term operating stability.

[0013] The method for preparing the above-mentioned formamidinium perovskite solar cell includes the following steps: S01: Cleaning the transparent conductive glass layer; S02: Preparing an aqueous dispersion solution by mixing a 30% tin oxide solution with deionized water, and then dropping and spin-coating it on the conductive glass layer to prepare a tin oxide electron transport layer; S03: Dropping a mixed solution of 0.3 mM to 5 mM of 4,4',4''-aminotribenzaldehyde and 1 to 1.6 M of lead iodide onto the tin oxide electron transport layer to prepare a lead iodide thin film, the solvent of the lead iodide solution being DMF and DMSO; further preparing an organic ligand solution, the organic ligand solution including 0.02 to 0.06 M of methylammonium iodide, 0.10 to 0.30 M of methylammonium chloride, and 0.4 to 0.7 M of formamidinium hydroiodide, and dropping the organic ligand solution onto the lead iodide thin film to prepare a perovskite layer; S04: Using isopropanol as a solvent, prepare a 2 - 6 mg / mL phenethylammonium iodide solution and drop it onto the perovskite layer to form a phenethylammonium iodide layer; S05: Prepare a Spiro - OMeTAD hole - transporting layer; S06: Evaporate molybdenum oxide and silver electrodes.

[0014] As a preferred embodiment, the volume ratio of the DMF to the DMSO is 9:1.

[0015] Furthermore, the operation of forming the lead iodide film in S03 is spin - coating at a speed of 1500 - 2000 revolutions per minute for 10 - 40 seconds and annealing at 70 °C for 0.5 - 3 minutes.

[0016] Furthermore, the operation of preparing the perovskite layer in S03 is spin - coating at 1600 - 2300 revolutions per minute for 10 - 40 seconds and annealing at 130 - 170 °C for 10 - 30 minutes under a relative humidity of 20 - 40%.

[0017] Furthermore, prepare a 60 - 90 mg / mL Spiro - OMeTAD solution in S05, further add 20 - 40 μL of 4 - tert - butylpyridine solution and 240 - 300 mg / mL of lithium bis(trifluoromethanesulfonyl)imide solution, and spin - coat on the phenethylammonium iodide layer at 2000 - 5000 revolutions per minute for 20 - 40 seconds.

[0018] Furthermore, evaporate 1 - 9 nm thick molybdenum oxide and 100 - 160 nm thick silver in S06; the silver electrode is disposed on the molybdenum oxide layer.

[0019] On the other hand, the present invention can also provide a method for preparing a highly stable perovskite solar cell based on a carbonyl compound. The method inhibits the non - optically active phase in the perovskite by introducing a three - dimensional compound having at least 3 carbonyl functional groups into the perovskite absorption layer. The three - dimensional compound having at least 3 carbonyl functional groups is 4,4’,4’’ - triaminotriphenylmethanal, and its molar concentration ratio to lead iodide in the perovskite absorption layer includes 0.3 mM:1 - 1.6 M, 0.6 mM:1 - 1.6 M, 1 mM:1 - 1.6 M, 2 mM:1 - 1.6 M, 3 mM:1 - 1.6 M, 4 mM:1 - 1.6 M, or 5 mM:1 - 1.6 M.

[0020] Furthermore, the solvent of the lead iodide solution is DMF and DMSO; the volume ratio of the DMF to the DMSO is 9:1.

[0021] Furthermore, the specific preparation steps of the method are as follows: S01: Clean the transparent conductive glass layer; S02: Prepare a water-dispersed solution by adding deionized water to a 30% tin oxide solution, and then dropwise spin-coat it on the conductive glass layer to prepare a tin oxide electron transport layer; S03: Dropwise spin-coat a mixed solution of 4,4’,4’’-aminotribenzaldehyde and 1 - 1.6 M lead iodide onto the tin oxide electron transport layer to form a lead iodide thin film; the molar concentration ratio of 4,4’,4’’-aminotribenzaldehyde to lead iodide includes 0.3 mM:1 - 1.6 M, 0.6 mM:1 - 1.6 M, 1 mM:1 - 1.6 M, 2 mM:1 - 1.6 M, 3 mM:1 - 1.6 M, 4 mM:1 - 1.6 M, or 5 mM:1 - 1.6 M; further prepare an organic ligand solution, the organic ligand solution includes 0.02 - 0.06 M methylammonium iodide, 0.10 - 0.30 M methylammonium chloride, and 0.4 - 0.7 M formamidinium hydroiodide, and drop the organic ligand solution onto the lead iodide thin film and spin-coat it to prepare a perovskite layer; S04: Using isopropanol as a solvent, prepare a 2 - 6 mg / mL phenethylammonium iodide solution and spin-coat it onto the perovskite layer to prepare a phenethylammonium iodide layer; S05: Prepare a Spiro-OMeTAD hole transport layer; S06: Evaporate molybdenum oxide and silver electrodes.

[0022] Beneficial technical effects: The present invention first provides a novel formamidinium-based perovskite solar cell. Only the compound molecule 4,4’,4’’-aminotribenzaldehyde with at least 3 carbonyl groups and a three-dimensional spatial structure is introduced into the perovskite absorption layer of this solar cell. Experiments have proved that 4,4’,4’’-aminotribenzaldehyde can stabilize the optical active phase of the perovskite (the peak at 2theta of 11.7° corresponds to the non-optical active phase, which does not appear in the XRD, indicating that the non-optical active phase is significantly inhibited). And the highest power conversion efficiency of this perovskite solar cell is 24.6%, and it can maintain more than 90% of the initial PCE after 1000h of stability testing. This shows that the novel formamidinium-based perovskite solar cell provided by the present invention has long-term operation stability.

[0023] The present invention also provides a preparation method for the above-mentioned novel formamidinium-based perovskite solar cell. The process of this method is overall simple and efficient. Only introducing 4,4’,4’’-aminotribenzaldehyde during the preparation of the perovskite light absorption layer can achieve the above technical purpose. Therefore, the preparation method provided by the present invention has the potential for large-scale industrial production. Description of the Drawings

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts do not necessarily draw according to the actual scale. Obviously, the following-described drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings.

[0025] Figure 1 Schematic structural diagram of the perovskite solar cell prepared in Example 1 of the present invention; Figure 2 Microscopic structure diagram of the perovskite thin film prepared in Example 1 of the present invention (scale: 1μm); Figure 3 Microscopic structure diagram of the perovskite thin film prepared in Example 4 of the present invention (scale: 1μm); Figure 4 XRD spectra of the perovskite thin films prepared in Examples 1 and 4 of the present invention; Figure 5 PCE spectra of the long-term operation stability of the perovskite solar cells prepared in Examples 1 and 4 of the present invention; Figure 6 Microscopic structure diagram of the perovskite thin film prepared in Example 4 of the present invention (scale: 1μm).

[0026] Summary of reference numerals: 101: ITO conductive glass layer, 102: electron transport layer, 103: perovskite absorption layer, 104: hole transport layer, 105: molybdenum oxide layer, 106: silver electrode layer. Detailed embodiments

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0028] As used herein, "and / or" includes any and all combinations of one or more of the listed related items.

[0029] As used herein, "a plurality of" means two or more, that is, it includes two, three, four, five, etc.

[0030] As used in this specification, the term "about" typically means + / - 5% of the value, more typically + / - 4% of the value, more typically + / - 3% of the value, more typically + / - 2% of the value, even more typically + / - 1% of the value, and even more typically + / - 0.5% of the value.

[0031] In this specification, certain embodiments may be disclosed in a format that is within a certain range. It should be understood that this description of "within a certain range" is merely for convenience and brevity and should not be construed as a rigid limitation on the disclosed range. Therefore, the description of the range should be considered to have specifically disclosed all possible sub-ranges and individual numerical values within that range. For example, the description of the range 1 - 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as the individual numbers within that range, such as 1, 2, 3, 4, 5, and 6. The above rules apply regardless of the breadth of the range.

[0032] Glossary of terms: The "photoactive phase" as described in the present invention refers to the phase corresponding to the peak at 2theta = 13.9° in the XRD, which is the photoactive phase in the perovskite.

[0033] The "non - photoactive phase" as described in the present invention refers to the phase corresponding to the peak at 2theta = 11.7° in the XRD, which is the non - photoactive phase in the perovskite.

[0034] Example 1 This example provides a method for preparing a perovskite solar cell, and the specific steps are as follows.

[0035] S01: Treat the ITO conductive glass: Wash the ITO conductive glass several times with detergent, deionized water, acetone, and isopropanol, and then use an ultraviolet ozone cleaner to clean the ITO conductive glass for 20 - 40 minutes.

[0036] S02: Prepare the tin oxide electron transport layer: Configure a 30% tin oxide dispersion into an aqueous dispersion solution. Add deionized water to the 30% tin oxide solution and shake. The volume ratio of the 30% tin oxide solution to deionized water is 1:3 to 1:4. Drop the prepared dispersion on the cleaned ITO conductive glass and spin - coat it at a speed of 2000 - 5000 revolutions per minute, and then anneal it at 130 - 170°C for 20 - 40 minutes.

[0037] S03: Preparation of perovskite absorption layer: Under an inert gas atmosphere, a 1.0 - 1.6 M lead iodide (PbI₂) solution (DMF:DMSO volume ratio of 9:1) is dropped onto the tin oxide electron transport layer and spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, followed by annealing at 70 °C for 0.5 - 3 minutes; Using isopropanol as a solvent, an organic ligand solution of 0.02 - 0.06 M methylammonium iodide (MAI), 0.10 - 0.30 M methylammonium chloride (MACl), and 0.4 - 0.7 M formamidinium hydroiodide (FAI) is prepared; The above organic ligand solution is dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Anneal at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity.

[0038] S04: Preparation of phenethylammonium iodide layer: Using isopropanol as a solvent, a 2 - 6 mg / mL phenethylammonium iodide solution is prepared and spin-coated onto the perovskite layer at 3000 - 4000 revolutions per minute.

[0039] S05: Preparation of hole transport layer: Using chlorobenzene as a solvent, a 60 - 90 mg / mL Spiro-OMeTAD solution is prepared. In addition, 20 - 40 μL of 4-tert-butylpyridine (TBP) solution and a solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) with a concentration of 240 - 300 mg / mL in acetonitrile are added to this solution; The mixed solution is dropped onto the phenethylammonium iodide layer and spin-coated at 2000 - 5000 revolutions per minute for 20 - 40 seconds. Place it in dry air for 10 - 36 h.

[0040] S06: Evaporate 1 - 9 nm of molybdenum oxide and 100 - 160 nm of silver.

[0041] The structural schematic diagram of the perovskite solar cell prepared in this example is as Figure 1 shown, Figure 1 From bottom to top are the ITO conductive glass layer (101), electron transport layer (102), perovskite absorption layer (103), hole transport layer (104), molybdenum oxide layer (105), and silver electrode layer (106). The microscopic structure diagram of this perovskite film is as Figure 2 shown, and the perovskite grains are smaller and there are pores on the surface.

[0042] Example 2 This example provides another example of the preparation of the perovskite absorption layer.

[0043] Under an inert gas atmosphere, a mixed solution of 0.3 mM of 4,4’,4’’-aminotribenzaldehyde and 1.0 - 1.6 M of lead iodide (DMF:DMSO volume ratio is 9:1) was dropped onto the tin oxide electron transport layer, spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, and annealed at 70 °C for 0.5 - 3 minutes; A mixed solution of 0.02 - 0.06 M of methylammonium iodide (MAI), 0.10 - 0.30 M of methylammonium chloride (MACl), and 0.4 - 0.7 M of formamidinium hydroiodide (FAI) was prepared with isopropanol as the solvent; The above mixed solvent was dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Annealed at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity.

[0044] Example 3 This example provides another example of the preparation of a perovskite absorption layer.

[0045] Under an inert gas atmosphere, a mixed solution of 0.6 mM of 4,4’,4’’-aminotribenzaldehyde and 1.0 - 1.6 M of lead iodide (DMF:DMSO volume ratio is 9:1) was dropped onto the tin oxide electron transport layer, spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, and annealed at 70 °C for 0.5 - 3 minutes; A mixed solution of 0.02 - 0.06 M of methylammonium iodide (MAI), 0.10 - 0.30 M of methylammonium chloride (MACl), and 0.4 - 0.7 M of formamidinium hydroiodide (FAI) was prepared with isopropanol as the solvent; The above mixed solvent was dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Annealed at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity.

[0046] Example 4 This example provides another example of the preparation of a perovskite absorption layer.

[0047] Under an inert gas atmosphere, a mixed solution of 1 mM of 4,4’,4’’-aminotribenzaldehyde and 1.0 - 1.6 M of lead iodide (DMF:DMSO volume ratio is 9:1) was dropped onto the tin oxide electron transport layer, spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, and annealed at 70 °C for 0.5 - 3 minutes; A mixed solution of 0.02 - 0.06 M of methylammonium iodide (MAI), 0.10 - 0.30 M of methylammonium chloride (MACl), and 0.4 - 0.7 M of formamidinium hydroiodide (FAI) was prepared with isopropanol as the solvent; The above mixed solvent was dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Annealed at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity.

[0048] The perovskite solar cells prepared by the method of this embodiment were subjected to structural characterization, and their microstructural diagrams are as shown in Figure 3 . It exhibits obvious perovskite structural characteristics. However, compared with the perovskite solar cells prepared by the method of Example 1 (without adding 4,4',4''-aminotribenzaldehyde), those of this embodiment have significantly larger grain characteristics and closer contacts between the crystals.

[0049] Example 5 This embodiment provides another example of preparing a perovskite absorption layer.

[0050] Under an inert gas atmosphere, a mixed solution of 2 mM of 4,4',4''-aminotribenzaldehyde and 1.0 - 1.6 M of lead iodide (DMF:DMSO volume ratio is 9:1) was dropped onto the tin oxide electron transport layer, spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, and annealed at 70 °C for 0.5 - 3 minutes; a mixed solution of 0.02 - 0.06 M of methylammonium iodide (MAI), 0.10 - 0.30 M of methylammonium chloride (MACl), and 0.4 - 0.7 M of formamidinium hydroiodide (FAI) was prepared with isopropanol as the solvent; the above mixed solvent was dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Anneal at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity.

[0051] Example 6 This embodiment provides another example of preparing a perovskite absorption layer.

[0052] Under an inert gas atmosphere, a mixed solution of 3 mM of 4,4',4''-aminotribenzaldehyde and 1.0 - 1.6 M of lead iodide (DMF:DMSO volume ratio is 9:1) was dropped onto the tin oxide electron transport layer, spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, and annealed at 70 °C for 0.5 - 3 minutes; a mixed solution of 0.02 - 0.06 M of methylammonium iodide (MAI), 0.10 - 0.30 M of methylammonium chloride (MACl), and 0.4 - 0.7 M of formamidinium hydroiodide (FAI) was prepared with isopropanol as the solvent; the above mixed solvent was dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Anneal at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity.

[0053] Example 7 This embodiment provides another example of preparing a perovskite absorption layer.

[0054] Under an inert gas atmosphere, a mixed solution of 4 mM of 4,4’,4’’-aminotribenzaldehyde and 1.0 - 1.6 M of lead iodide (DMF:DMSO volume ratio is 9:1) was dropped onto the tin oxide electron transport layer, spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, and annealed at 70 °C for 0.5 - 3 minutes; A mixed solution of 0.02 - 0.06 M of methylammonium iodide (MAI), 0.10 - 0.30 M of methylammonium chloride (MACl), and 0.4 - 0.7 M of formamidinium hydroiodide (FAI) was prepared using isopropyl alcohol as the solvent; The above mixed solvent was dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Anneal at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity.

[0055] Example 8 This example provides another example of preparing a perovskite absorption layer.

[0056] Under an inert gas atmosphere, a mixed solution of 5 mM of 4,4’,4’’-aminotribenzaldehyde and 1.0 - 1.6 M of lead iodide (DMF:DMSO volume ratio is 9:1) was dropped onto the tin oxide electron transport layer, spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, and annealed at 70 °C for 0.5 - 3 minutes; A mixed solution of 0.02 - 0.06 M of methylammonium iodide (MAI), 0.10 - 0.30 M of methylammonium chloride (MACl), and 0.4 - 0.7 M of formamidinium hydroiodide (FAI) was prepared using isopropyl alcohol as the solvent; The above mixed solvent was dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Anneal at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity.

[0057] Example 9 This example provides another example of preparing a perovskite absorption layer.

[0058] Under an inert gas atmosphere, a mixed solution of 6 mM of 4,4’,4’’-aminotribenzaldehyde and 1.0 - 1.6 M of lead iodide (DMF:DMSO volume ratio is 9:1) was dropped onto the tin oxide electron transport layer, spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, and annealed at 70 °C for 0.5 - 3 minutes; A mixed solution of 0.02 - 0.06 M of methylammonium iodide (MAI), 0.10 - 0.30 M of methylammonium chloride (MACl), and 0.4 - 0.7 M of formamidinium hydroiodide (FAI) was prepared using isopropyl alcohol as the solvent; The above mixed solvent was dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Anneal at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity.

[0059] Example 10 Result Characterization

[0060] Table 1 Content of 4,4’,4’’-Aminotribenzaldehyde in Examples 1-9 For the perovskite solar cells prepared according to the methods of Examples 2-9, the electron transport layer is a tin oxide thin film with a thickness range of 40-60 nm; the perovskite light absorption layer is formamidinium perovskite (FAPbI 3 ), with a thickness range of 700-800 nm; the hole transport layer is Spiro-OMeTAD; the molybdenum oxide layer has a thickness range of 2-5 nm; and the silver electrode layer has a thickness range of 90-110 nm.

[0061] 1. XRD Test Experimental Method: The prepared perovskite thin film was detected by ESCALAB 250Xi (Thermo Fisher).

[0062] Table 2 XRD Test Results 2. Long-Term Operational Stability Test Experimental Method: The photocurrent density-voltage (J-V) curve was measured using a solar simulator equipped with a 450 W xenon lamp (Newport 6279 NS) and a Keithley 2400 light source meter. The effective area of the device under test is 0.08 cm 2 (calibration mask). The J-V curve was scanned from -0.1 to 1.2 V (forward scan) or from 1.2 to -0.1 V (reverse scan) at a scan rate of 100 mV −1 . Using a standard Si solar cell calibrated by the National Institute of Metrology (NIM) of the United States, the light intensity was adjusted to AM 1.5G one sun (100 mW cm −2 ). The prepared cells were subjected to J-V tests at 0, 100, 200, 400, 600, 800, and 1000 h, and the PCE was recorded.

[0063] Table 3 PCE Results The results show that the perovskite solar cells containing 1 mM of 4,4’,4’’-aminotribenzaldehyde can maintain more than 90% of the initial PCE after 1000 hours of testing. While the PCE of the perovskite solar cells without adding 4,4’,4’’-aminotribenzaldehyde is 61% of the initial value after 1000 hours of testing.

[0064] 3. Power Conversion Efficiency During the measurement of the photocurrent density-voltage (J-V) curve, the power conversion efficiency (PCE) is the ratio of the maximum output power Pmax of the device to the input power Pin of the incident light.

[0065] Table 4 Power conversion efficiency (PCE) of different examples Conclusion: The perovskite solar cell containing 1 mM of 4,4’,4’’-aminotribenzaldehyde has the best photoelectric conversion efficiency, and its photoelectric conversion efficiency is 24.6%. The photoelectric conversion efficiencies of other addition amounts (0.3 - 5 mM) are greater than those of the devices without adding 4,4’,4’’-aminotribenzaldehyde.

[0066] Example 11 This example provides another control example.

[0067] Under an inert gas atmosphere, a mixed solution of 3 mM of 4-butylbenzaldehyde (C 11 H 14 O) containing 1 carbonyl group and 1.0 - 1.6 M of lead iodide (DMF:DMSO volume ratio is 9:1) was dropped onto the tin oxide electron transport layer, spin-coated at 1500 - 2000 revolutions per minute for 10 - 40 seconds, and annealed at 70 °C for 0.5 - 3 minutes; Using isopropanol as the solvent, an organic ligand solution of 0.02 - 0.06 M of methylammonium iodide (MAI), 0.10 - 0.30 M of methylammonium chloride (MACl), and 0.4 - 0.7 M of formamidinium hydroiodide (FAI) was prepared; The above organic ligand solution was dropped onto the annealed lead iodide film and spin-coated at 1600 - 2300 revolutions per minute for 10 - 40 seconds. Annealed at 130 - 170 °C for 10 - 30 minutes under 20 - 40% relative humidity. Among them Figure 6 is the SEM micrograph of adding 4-butylbenzaldehyde (C 11 H 14 O). It can be seen from the figure that there are holes on the perovskite surface and the crystals are small.

[0068] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention. These all belong to the protection scope of the present invention.

Claims

1. A formamidite-based perovskite solar cell with long-term operational stability, characterized in that: The formamidinium-based perovskite solar cell consists of a conductive glass layer, an electron transport layer, a perovskite absorption layer, a hole transport layer and an electrode group layer from bottom to top; the perovskite absorption layer is a formamidinium-based perovskite absorption layer with a thickness ranging from 700 to 800 nm; the formamidinium-based perovskite absorption layer includes a lead iodide film made of a three-dimensional compound having at least three carbonyl functional groups and lead iodide; the three-dimensional compound having at least three carbonyl functional groups is 4,4',4''-nitrogen tribenzaldehyde; the molar concentration ratio of the 4,4',4''-nitrogen tribenzaldehyde to the lead iodide is 0.3~5mM:1~1.6M.

2. The formamidinium-based perovskite solar cell according to claim 1, characterized in that: The molar concentration ratio of the 4,4',4''-nitrotribenzaldehyde to the lead iodide includes 0.3mM:1~1.6M, 0.6mM:1~1.6M, 1mM:1~1.6M, 2mM:1~1.6M, 3mM:1~1.6M, 4mM:1~1.6M or 5mM:1~1.6M.

3. The formamidinium-based perovskite solar cell according to claim 2, characterized in that: The molar concentration ratio of the 4,4',4''-nitrotribenzaldehyde to the lead iodide is 1mM:1-1.6M.

4. The formamidinium-based perovskite solar cell according to claim 1, characterized in that: The formamidine-based perovskite absorption layer also includes a mixed salt solution made from 0.02-0.06 M methylammonium iodide, 0.10-0.30 M methylammonium chloride and 0.4-0.7 M formamidine hydroiodide.

5. The method for preparing a formamidine-based perovskite solar cell according to any one of claims 1 to 4, characterized in that: The following steps are involved: S01: Cleaning the transparent conductive glass layer; S02: adding deionized water to a 30% tin oxide solution by mass to prepare a water dispersion solution, and then dripping it onto the conductive glass layer to prepare a tin oxide electron transport layer; S03: adding a mixed solution of 0.3mM~5mM 4,4',4''-nitrotribenzaldehyde and 1~1.6M lead iodide to the tin oxide electron transport layer to prepare a lead iodide film, wherein the solvent of the lead iodide solution is DMF and DMSO; further preparing an organic ligand solution, wherein the organic ligand solution includes 0.02~0.06M methylammonium iodide, 0.10~0.30M methylammonium chloride and 0.4~0.7M formamidine hydroiodide, and adding the organic ligand solution to the lead iodide film to prepare a perovskite layer; S04: Using isopropanol as solvent, prepare a 2-6 mg / mL phenethylammonium iodide solution and drop it onto the perovskite layer to prepare a phenethylammonium iodide layer; S05: Preparation of Spiro-OMeTAD hole transport layer; S06: Evaporation of molybdenum oxide and silver electrodes.

6. The preparation method according to claim 5, characterized in that: The volume ratio of the DMF to the DMSO is 9:

1.

7. The preparation method according to claim 5, characterized in that: The operation of forming the lead iodide film in S03 is to spin-coat at a spin-coating speed of 1500-2000 rpm for 10-40 seconds and anneal at 70° C. for 0.5-3 minutes.

8. The preparation method according to claim 5, characterized in that: The operation of preparing the perovskite layer in S03 is to spin coat at 1600-2300 rpm for 10-40 seconds and anneal at 130-170° C. for 10-30 minutes at a relative humidity of 20-40%.

9. The preparation method according to claim 5, characterized in that Prepare 60-90 mg / mL of Spiro-OMeTAD solution in S05, further add 20-40 μL of 4-tert-butylpyridine solution and 240-300 mg / mL of lithium bis(trifluoromethanesulfonyl)imide solution, and spin-coat on the phenethylammonium iodide layer at 2000-5000 rpm for 20-40 seconds.

10. The preparation method according to claim 5, characterized in that: In S06, molybdenum oxide with a thickness of 1-9 nm and silver with a thickness of 100-160 nm are evaporated; the silver electrode is arranged on the molybdenum oxide layer.

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