Metal halide perovskite thin film, preparation method thereof and photovoltaic device

Abstract

The invention relates to the technical field of perovskite photovoltaics, and particularly discloses a metal halide perovskite thin film, a preparation method of the metal halide perovskite thin film and a photovoltaic device. And introducing a halogen simple substance on a wet film formed by the solution to carry out an in-situ reaction. According to the invention, the nucleation and growth process of perovskite is regulated and controlled through the in-situ reaction of the organic additive containing active hydrogen and the halogen simple substance, so that the formation of defects such as halogen vacancies and the like is effectively inhibited, the vicious circle of vacancy defect-ion migration-halogen simple substance regeneration is blocked, and high-quality, uniform and compact film formation of perovskite is realized; the photovoltaic device prepared from the perovskite thin film has high photoelectric conversion rate and high stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of perovskite photovoltaic, in particular to a metal halide perovskite thin film, a preparation method thereof and a photovoltaic device. BACKGROUND

[0002] Organic-inorganic metal halide perovskite has the advantages of rich material sources, simple preparation process, high carrier mobility, etc., and is considered as a new type of photovoltaic material with important application prospect in the field of energy. In recent years, through continuous optimization, the photoelectric conversion efficiency of perovskite photovoltaic devices has exceeded 27%, but the stability of perovskite photovoltaic devices still cannot meet the commercialization demand. The fundamental reason is that there are a large number of defects in the perovskite thin film, which easily induces serious ion migration during the operation of the device, and further leads to the volatilization of organic components such as iodine element. The escape of the organic components promotes the continuous generation of new defect states, and accelerates the performance degradation of the device. In addition, the poor uniformity of the thin film limits the preparation of large-area thin film and device.

[0003] Therefore, it is urgent to further optimize the perovskite material and its preparation process, to break the vicious cycle of "vacancy defect-ion migration-halogen element regeneration", and to improve the long-term operation stability of the photovoltaic device.

[0004] Based on this technical background, the present application provides a preparation scheme of a high-performance metal halide perovskite thin film. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a metal halide perovskite thin film, a preparation method thereof and a photovoltaic device. The perovskite thin film is prepared by using an air extraction method, and through in-situ reaction of an active hydrogen-containing organic additive and halogen element, the perovskite nucleation and growth process is regulated, high-quality, uniform and dense film formation is promoted, the formation of fluorescence quenching center in the perovskite crystal growth process is inhibited, and the vicious cycle of "vacancy defect-ion migration-halogen element regeneration" is broken.

[0006] In order to achieve the above purpose, the first aspect of the present application provides a metal halide perovskite thin film, which is prepared by adding an active hydrogen-containing organic additive to a perovskite precursor solution, and further introducing halogen element on the wet film formed by the solution to generate in-situ reaction; The metal halide perovskite is a three-dimensional perovskite of ABX3 type or a quasi-two-dimensional perovskite of (A')2A n-1 B n X 3n+1 type, wherein A' is a long-chain organic cation, A is CH3NH3 + , HC(NH2)2 + , C(NH2)3 + , Cs +and Rb + At least one of the following, B is at least one of a Group IV main metal ion or a transition metal ion, and X is Cl. - ,Br - I - At least one of them.

[0007] According to the present invention, the ABX3 type three-dimensional perovskite precursor solution is obtained by dissolving AX and BX2 in a polar solvent at a molar ratio of 0.8~1.5:0.8~1.5; (A′)2A n-1 B n X 3n+1 The quasi-two-dimensional perovskite precursor solution was obtained by dissolving A′X, AX and BX2 in a polar solvent at a molar ratio of 0.01~10:0.8~1.5:0.8~1.5. The precursor solution concentration is 0.5~2.5 mol / L; The concentration of the organic additive containing active hydrogen in the precursor solution is 0.5~30 mg / ml, preferably 2~10 mg / ml.

[0008] According to the present invention, the α position of the active hydrogen in the organic additive is a group with electron-withdrawing or conjugated properties; the group with electron-withdrawing or conjugated properties includes carbonyl, benzene ring, pyridine ring, alkenyl, nitro or alkynyl.

[0009] According to the present invention, the organic additive containing active hydrogen is 4-fluorophenylacetophenone, 1,2-bis(4-fluorophenyl)acetophenone, 4'-methoxy-2-phenylacetophenone, 2-(4-fluorophenyl)acetophenone, benzoylacetone, dibenzoylmethane, 4-chlorophenylbenzyl ketone, 1,3-bis(4-fluorophenyl)propane-1,3-dione, 1-(4-chlorophenyl)-2-(3,4-difluorophenyl)ethane-1-one, 1-(4-chlorophenyl)-2-(4-fluorophenyl)ethane-1-one, 1-(4-fluorophenyl)-1,3-butanedione, 4,4,4-trifluoro-1-(4-fluorophenyl)butane-1,3-dione, 4,4,4-trifluoro-1-(4-methoxy)acetophenone, 4,4,4-trifluoro-1-(4-methoxy)acetophenone, 4,4,4-trifluoro-1-(4-fluorophenyl)butane-1,3-di ... At least one of the following: (4-nitrophenyl)-1,3-butanedione, (4-nitrobenzoyl)pyruvate, 1,3-indanedione, 4,5,6,7-tetrachloroindanedione, 4-nitro-1H-indanedione, 1H-cyclopenta[b]naphthyl-1,3(2H)-dione, symmetric indarsen-1,3,5,7(2H,6H)-tetraone, 1-(4-fluorophenyl)-3-(2-hydroxyphenyl)propane-1,3-dione, 1-(3-nitrophenyl)-1,3-butanedione, 1,3-bis(4-chlorophenyl)-1,3-propanedione, and 1-(4-chlorophenyl)-3-(2-hydroxyphenyl)propane-1,3-dione.

[0010] A second aspect of the present invention provides a method for preparing the above-mentioned perovskite thin film, comprising: A perovskite wet film was obtained by vacuuming, and the wet film was then subjected to high-temperature annealing to obtain a perovskite thin film. The evacuation method involves placing a liquid film formed by the precursor solution inside a vacuum chamber, and introducing halogen elemental gas during the evacuation phase in the vacuum chamber to cause an in-situ reaction. The precursor solution forms a liquid film by spin coating or blade coating.

[0011] According to the present invention, the halogen elemental gas exists in solution form before volatilization; the solute in the solution is at least one of Cl2, Br2 and I2, preferably I2; The concentration of the halogen element is 0.01~5 mg / ml, preferably 0.1~1 mg / ml.

[0012] According to the present invention, the solvent of the solution is a polar solvent and / or a non-polar solvent; The polar solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone, preferably N,N-dimethylformamide; The nonpolar solvent is at least one of chlorobenzene, ethyl acetate, toluene, and anisole, preferably chlorobenzene or ethyl acetate.

[0013] According to the present invention, the rotation speed of the spin coating method is 2000~10000 rpm, and the time is 3~600s; The blade coating method is used to prepare liquid films by using a doctor blade or slit coating. The coating speed is 2~200 mm / s, the blade height is 50~300 µm, and the liquid injection speed is 10~1000 µl / s. The high-temperature annealing temperature is 50~200°C and the time is 10~100min.

[0014] According to the present invention, the perovskite thin film has a surface area of ​​0.1 cm². 2 up to 50m 2 ; The air pressure in the vacuum chamber during the evacuation process is 1~1000Pa.

[0015] A third aspect of the present invention provides a photovoltaic device having the above-described perovskite thin film, or having a perovskite thin film prepared by the above-described preparation method, comprising a substrate layer, an electrode layer, an electrode modification layer, a hole transport-electron blocking layer, an electron transport-hole blocking layer, and a functional layer. The functional layer includes a perovskite thin film.

[0016] The beneficial effects of this invention include: (1) The metal halide perovskite thin film proposed in this invention adds an organic additive containing active hydrogen to the perovskite precursor solution and introduces halogen gas into it during the gas extraction stage, so that the halogen reacts in situ with the organic additive containing active hydrogen, thereby regulating the nucleation and growth process of perovskite, promoting high-quality, uniform and dense film formation, inhibiting the formation of fluorescence quenching centers during the crystal growth of perovskite, blocking the vicious cycle of "vacancy defects - ion migration - halogen regeneration", and achieving high-quality, uniform and dense perovskite film formation.

[0017] (2) The photovoltaic device with perovskite thin film proposed in this invention achieves a photoelectric conversion efficiency of up to 26.57%, and the stability is significantly improved. The device has a thermal stability of up to 7000h at 85 degrees Celsius. This technical solution is very suitable for the preparation of high-performance flexible perovskite photovoltaic devices.

[0018] (3) This invention enables large-area, batch, and controllable preparation and production of high-quality perovskite thin films, and the devices prepared based on these films exhibit excellent photovoltaic performance. It solves the vicious cycle problem of "vacancy defects - ion migration - halogen regeneration" that is easily caused in the preparation of large-area thin films in the prior art, thereby significantly improving the photovoltaic performance of the devices.

[0019] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0020] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings.

[0021] Figure 1 This is a schematic diagram of the structure of the photovoltaic device with perovskite thin film proposed in this invention.

[0022] Figure 2 This is a schematic diagram of the preparation process of the ABX3 type metal halide perovskite thin film proposed in this invention.

[0023] Figure 3 This is a cross-sectional SEM image of a specific embodiment of the ABX3 type metal halide perovskite thin film proposed in this invention.

[0024] Figure 4 This is a schematic diagram illustrating the evolution of the absorption intensity of the metal halide complex and the perovskite phase during the perovskite film formation process in a specific embodiment of the ABX3 type metal halide perovskite thin film proposed in this invention.

[0025] Figure 5This is a schematic diagram illustrating the evolution of the perovskite metal halide complex and the three-dimensional perovskite in a specific embodiment of the ABX3 type metal halide perovskite thin film proposed in this invention.

[0026] Figure 6 This is a two-dimensional schematic diagram of the photoluminescence intensity of the perovskite thin film in a specific embodiment of the ABX3 type metal halide perovskite thin film proposed in this invention.

[0027] Figure 7 This is a two-dimensional schematic diagram of the electroluminescence intensity of a perovskite photovoltaic device in a specific embodiment of the photovoltaic device with a perovskite thin film proposed in this invention.

[0028] Figure 8 This is a schematic diagram of the current-voltage curve in a specific embodiment of the photovoltaic device with perovskite thin film proposed in this invention.

[0029] Figure 9 This is a schematic diagram illustrating the thermal stability of a photovoltaic device with a perovskite thin film proposed in this invention.

[0030] Figure 10 This is a schematic diagram of the current-voltage curve in another specific embodiment of the photovoltaic device with perovskite thin film proposed in this invention.

[0031] Figure 11 This is a schematic diagram of the current-voltage curve in the third specific embodiment of the photovoltaic device with perovskite thin film proposed in this invention.

[0032] Figure 12 This is a schematic diagram of the current-voltage curve in the fourth specific embodiment of the photovoltaic device with perovskite thin film proposed in this invention.

[0033] Figure 13 This is a schematic diagram of the current-voltage curve in the fifth specific embodiment of the photovoltaic device with perovskite thin film proposed in this invention.

[0034] Figure 14 This is a schematic diagram of the current-voltage curve in the sixth specific embodiment of the photovoltaic device with perovskite thin film proposed in this invention.

[0035] Figure 15 This is a two-dimensional schematic diagram of the photoluminescence intensity of the perovskite film in the seventh specific embodiment of the ABX3 type metal halide perovskite film proposed in this invention.

[0036] Figure 16 This is a two-dimensional schematic diagram of the electroluminescence intensity of the perovskite photovoltaic device in the seventh specific embodiment of the ABX3 type metal halide perovskite thin film proposed in this invention.

[0037] Figure 17 This is a schematic diagram of the current-voltage curve in the seventh specific embodiment of the photovoltaic device with perovskite thin film proposed in this invention.

[0038] Figure 18 This is a two-dimensional schematic diagram of the photoluminescence intensity of the perovskite film in the eighth specific embodiment of the ABX3 type metal halide perovskite film proposed in this invention.

[0039] Figure 19 This is a two-dimensional schematic diagram of the electroluminescence intensity of the perovskite photovoltaic device in the eighth specific embodiment of the ABX3 type metal halide perovskite thin film proposed in this invention.

[0040] Figure 20 This is a schematic diagram of the current-voltage curve in the eighth specific embodiment of the photovoltaic device with perovskite thin film proposed in this invention.

[0041] Figure 21 This is a schematic diagram of the current-voltage curve in the ninth specific embodiment of the photovoltaic device with perovskite thin film proposed in this invention.

[0042] Figure 22 This is a schematic diagram of the current-voltage curve of the perovskite photovoltaic device of Comparative Example 1 of the present invention.

[0043] Figure 23 This is a schematic diagram of the current-voltage curve of the perovskite photovoltaic device of Comparative Example 2 of the present invention.

[0044] Figure 24 This is a schematic diagram of the current-voltage curve of the perovskite photovoltaic device of Comparative Example 3 of the present invention.

[0045] Figure 25 This is a schematic diagram of the current-voltage curve of the perovskite photovoltaic device of Comparative Example 4 of the present invention. Detailed Implementation

[0046] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0047] This invention provides a metal halide perovskite thin film, such as... Figure 2 As shown, it includes: Perovskite thin films are prepared by adding an organic additive containing active hydrogen to a perovskite precursor solution and further introducing a halogen element onto the wet film formed in the solution to cause an in-situ reaction. In the ABX3 type metal halide perovskite structure, A is CH3NH3. + HC(NH2)2 +C(NH2) 3+ Cs + and Rb + At least one of the following, B is at least one of a Group IV main metal ion or a transition metal ion, and X is Cl. - ,Br - I - At least one of them; The preferred structure of the photovoltaic device of this invention is: glass substrate / FTO / SnO2 / FA. 0.98 Cs 0.02 The structure of a photovoltaic device is as follows: Pb(IBr)3 / Spiro-OMeTAD / MoO3 / Ag. Figure 1 As shown; The fabrication of photovoltaic devices can be achieved by cleaning a transparent conductive substrate, such as an FTO glass substrate. ① Preparation of electron transport-hole blocking layer: Take 100 ml of deionized water into a 500 ml volumetric flask, add 60 μL of mercaptoacetic acid (C2H4O2S) and 1.5 mL of HCl (37 wt% mass fraction), and then shake well; then dissolve 0.55 g of SnCl2·2H2O in the above prepared solution; add 2.5 g of urea to prepare a stock solution; place the FTO glass slide in a glass box, add 25 ml of the above stock solution to the glass box, and add 125 ml of deionized water to dilute; place the glass box in a 90°C oven for 3.5 h for aging; take out the FTO glass slide, ultrasonically clean it with deionized water for 5 minutes, then ultrasonically clean it with isopropanol (IPA) for 5 minutes, dry it with a dry nitrogen stream, and anneal it on a 170°C hot plate for 1 hour for later use; ② Preparation of halogen solutions: Prepare an ethyl acetate solution containing iodine (I2); ③ Preparation of perovskite precursor solution: AX and BX2 are dissolved in a polar solvent at a molar ratio of 0.8~1.5:0.8~1.5 to obtain perovskite precursor solution, and organic additive molecules containing active hydrogen are added to the precursor solution. ④ Preparation of the perovskite light-absorbing layer: In a nitrogen glove box, the perovskite precursor solution is coated onto the substrate surface by spin coating to form a perovskite liquid film; the liquid film is placed in a vacuum chamber, and iodine gas is introduced into the vacuum chamber during the evacuation phase; subsequently, the obtained perovskite wet film is annealed on a heating plate at 50°C~200°C for 10~100 minutes and cooled to room temperature; ⑤ Preparation of the hole transport-electron blocking layer: Weigh Spiro-OMeTAD powder, add 1 ml of chlorobenzene, then add 18 μl of Li-TFSI (520 mg / ml dissolved in acetonitrile), 29 μl of FK209 (300 mg / ml dissolved in acetonitrile), and 30 μl of 4-tert-butylpyridine, and stir for 1 h to ensure complete dissolution; prepare a thin film using a one-step spin coating method at a speed of 4000 rpm and a spin coating time of 30 s to obtain the hole transport-electron blocking layer covering the perovskite thin film; ⑥ Preparation of electrode modification layer and electrode: The prepared perovskite film is transferred to a vacuum evaporation chamber to prepare the electrode modification layer (MoO3) and electrode (Ag) at a pressure of 6 × 10⁻⁶. -7 When Torr deposits the electrode modification layer, the evaporation rate is controlled below 0.01 nm / s, the thickness is 4.5 nm, and the evaporation rate of the electrode is maintained at 0.1 nm / s.

[0048] In this invention, a photovoltaic device with a perovskite thin film achieves a photoelectric conversion efficiency of up to 26.57% and significantly improves stability, with a thermal stability of up to 7000 hours at 85 degrees Celsius. This technical solution is very suitable for the large-scale preparation and production of large-area, flexible perovskite thin films and photovoltaic devices.

[0049] The present invention will be described in more detail below through embodiments.

[0050] The solution preparation method of this invention includes: The perovskite ABX3 precursor solution was prepared by mixing AX and BX2 in a solvent at different concentrations; wherein A is a cationic group (including Rb). + Cs + MA + and FA + (any one or more of the following), B is a Group 4 metal (Pb) 2+ Sn 2+ ) or transition metal ions (Cu 2+ Ni 2+ Co 2+ Fe 2+ Mn 2+ Eu 2+ X is a halide ion (Cl). - , Br - I -The solvent refers to any one or more of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N-methylpyrrolidone (NMP); the concentration refers to the molar concentration of the solute (perovskite ABX3) in the solution being 0.5~2.5 mol / L; an organic additive containing active hydrogen is added to the above precursor solution at a concentration of 0.5~30 mg / ml. Example 1

[0051] FA 0.9 Cs 0.1 Fabrication of Pb(IBr)3 perovskite solar cells: Perovskite FA 0.98 Cs 0.02 The Pb(IBr)3 precursor solution was prepared by dissolving FAI(FABr), CsI(CsBr), and PbI2(PbBr2) in DMF / DMSO (4:1V / V) at a molar ratio of 0.98:0.02:1 and stirring at room temperature for 4 hours to obtain a 1.4 mol / L perovskite precursor solution. The overall structure of the photovoltaic device can be described as follows: glass substrate / FTO / SnO2 / FA 0.98 Cs 0.02 Pb(IBr)3 / Spiro-OMeTAD / MoO3 / Ag; Perovskite photovoltaic device structure as follows Figure 1 As shown, it includes a transparent conductive substrate layer, on which an electron transport-hole blocking layer, a perovskite light-absorbing layer, a hole transport-electron blocking layer, an electrode modification layer, and an electrode are sequentially disposed; Methods for fabricating perovskite photovoltaic devices include: ① The substrate is fluorine-doped tin oxide (FTO) conductive glass. The sheet resistance of the FTO film is 15Ω and the film thickness is 20-200nm. The transparent conductive substrate FTO glass is ultrasonically cleaned twice with isopropanol, acetone and ethanol solutions respectively. After drying the FTO glass with high-pressure nitrogen gas flow, the FTO is transferred to an oxygen plasma surface cleaner for oxygen plasma cleaning. ② Preparation of electron transport-hole blocking layer: Take 100 ml of deionized water into a 500 ml volumetric flask, add 60 μL of mercaptoacetic acid (C2H4O2S) and 1.5 mL of HCl (37 wt% mass fraction), and then shake well; then dissolve 0.55 g of SnCl2·2H2O in the above prepared solution; add 2.5 g of urea to prepare a stock solution; place the FTO glass slide in a glass box, add 25 ml of the above stock solution to the glass box, and add 125 ml of deionized water to dilute; place the glass box in a 90°C oven for 3.5 h for aging; take out the FTO glass slide, ultrasonically clean it with deionized water for 5 minutes, then ultrasonically clean it with isopropanol (IPA) for 5 minutes, dry it with a dry nitrogen stream, and anneal it on a 170°C hot plate for 1 hour for later use; ③ Preparation of halogen elemental solution: Add 3 mg of iodine to 20 ml of ethyl acetate, shake well to prepare an iodine elemental solution of 0.15 mg / ml, shake well and set aside; ④ Preparation of perovskite precursor solution: Add 2.5 mg of 4-fluorophenylacetophenone to 1 ml of perovskite precursor solution, with a concentration of 2.5 mg / ml, and shake well before use; ⑤ Preparation of the perovskite light-absorbing layer: In a nitrogen glove box, the perovskite precursor solution was spin-coated onto the substrate surface in one step to form a perovskite liquid film. The spin speed was 6000 rpm and the spin-coating time was 5 s. Subsequently, the liquid film was transferred to a sealed vacuum chamber, and the vacuum chamber was evacuated and dried. During the evacuation and drying process, iodine gas was introduced simultaneously, and the vacuum chamber pressure was maintained at 200 Pa by adjusting the valve (see...). Figure 2 The resulting perovskite wet film was annealed on a hot plate at 100°C for 60 min and then cooled to room temperature. ⑥ Preparation of the hole transport-electron blocking layer: Weigh 73 mg of Spiro-OMeTAD powder, add 1 ml of chlorobenzene, then add 18 μl of Li-TFSI (520 mg / ml dissolved in acetonitrile), 29 μl of FK209 (300 mg / ml dissolved in acetonitrile), and 30 μl of 4-tert-butylpyridine, and stir for 1 h to ensure complete dissolution; prepare a thin film using a one-step spin coating method at a speed of 4000 rpm and a spin coating time of 30 s to obtain the hole transport-electron blocking layer covering the perovskite thin film; ⑦ Preparation of electrode modification layer and electrode: The prepared perovskite film was transferred to a vacuum evaporation chamber to prepare the electrode modification layer (MoO3) and electrode (Ag) at a pressure of 6 × 10⁻⁶. -7 Torr, when depositing the electrode modification layer, controls the evaporation rate to below 0.01 nm / s and the thickness to 4.5 nm, while the electrode evaporation rate is maintained at 0.1 nm / s and the thickness to 80 nm. The fabricated perovskite photovoltaic device was subjected to current-voltage characteristic testing in a glove box. The cross-sectional morphology of the perovskite thin film obtained in this embodiment, regulated by the in-situ reaction of 4-fluorophenylacetophenone with elemental iodine, is as follows: Figure 3 As shown, it can be seen that a single perovskite grain penetrates the entire perovskite light-absorbing layer; the evolution of the lead-iodine complex and the perovskite phase during the perovskite film formation process is as follows. Figure 4 As shown, after degassing, the perovskite wet film mainly consists of a large number of low-dimensional inorganic PbI6 octahedral layers and three-dimensional perovskite. During continuous heating of the film, when the absorption intensity of the low-dimensional inorganic PbI6 octahedral layers rapidly decreases, the absorption intensity of the three-dimensional perovskite simultaneously and significantly increases. This indicates the transformation from the low-dimensional phase to the three-dimensional phase. A schematic diagram of nucleation and growth is shown below. Figure 5 As shown; the two-dimensional photoluminescence pattern (PL mapping) of the perovskite thin film and the electroluminescence (EL) of the device are respectively as follows. Figure 6 and Figure 7 As shown, both the photoluminescence intensity of the perovskite thin film and the electroluminescence intensity of the device are relatively uniform; the JV curve of the perovskite photovoltaic device regulated by the in-situ reaction of 4-fluorophenylacetophenone with elemental iodine is shown in the figure. Figure 8 It can be seen that the photoelectric conversion efficiency reaches 26.57%; under 85 degrees Celsius, the device's thermal stability is as high as 7000 hours. Figure 9 As shown. Example 2

[0052] The difference between this embodiment and Example 1 is that the concentration of 4-fluorophenylacetophenone in the perovskite precursor solution is 1 mg / ml. A one-step spin coating method is used to prepare the perovskite liquid film at a spin speed of 1000 rpm for 40 s. Subsequently, a perovskite wet film is prepared by a vacuum method. The obtained perovskite wet film is annealed on a hot plate at 150°C for 10 min and then cooled to room temperature. The photovoltaic device fabrication method is the same as in Example 1. The JV curve of the perovskite photovoltaic device prepared by in-situ reaction regulation of 1 mg / ml 4-fluorophenylacetophenone with elemental iodine is shown below. Figure 10 As shown, the photoelectric conversion efficiency reaches 25.97%. Example 3

[0053] The difference between this embodiment and Example 1 is that the concentration of the iodine solution is 4 mg / ml, a one-step spin coating method is used to prepare the perovskite liquid film, the spin speed is 1000 rpm, the spin coating time is 300 s, and then a perovskite wet film is prepared by the vacuum method; the obtained perovskite wet film is annealed on a hot plate at 100°C for 60 min and cooled to room temperature; the photovoltaic device fabrication method is the same as in Example 1. The JV curve of the perovskite photovoltaic device prepared by in-situ reaction of 4 mg / ml iodine with 4-fluorophenylacetophenone is shown below.Figure 11 As shown, the photoelectric conversion efficiency reaches 25.82%. Example 4

[0054] This example differs from Example 1 in that it utilizes a slit coating method to prepare a perovskite liquid film. Specifically, the perovskite precursor solution is placed in a syringe at an injection rate of 10 µl / s, the coating speed is 3 mm / s, and the tip height is 70 µm. The obtained perovskite wet film is transferred to a vacuum chamber, and a perovskite thin film is prepared using a vacuum method. The active area of ​​the device is 0.45 cm². 2 The remaining steps in the fabrication of other devices are the same as in Example 1. The JV curve of the perovskite photovoltaic device prepared by the slit coating method is shown below. Figure 12 As shown, the photoelectric conversion efficiency reaches 21.77%. Example 5

[0055] This example differs from Example 4 in that the coating speed is 100 mm / s, the blade height is 120 µm, and the liquid injection speed is 1000 µl / s; the active area of ​​the device is 0.45 cm². 2 The remaining steps in the fabrication of other devices are the same as in Example 1. The JV curve of the perovskite photovoltaic device prepared by the slit coating method is shown below. Figure 13 As shown, the photoelectric conversion efficiency reaches 21.35%. Example 6

[0056] This example differs from Example 1 in that it utilizes a slit coating method to prepare a large-area perovskite liquid film. Specifically, the perovskite precursor solution is placed in a syringe at an injection rate of 10 µl / s, the coating speed is 3 mm / s, and the tip height is 70 µm. The obtained perovskite wet film is transferred to a vacuum chamber, and a perovskite thin film is prepared using a vacuum method. The active area of ​​the component is ~15 cm². 2 The remaining steps in the fabrication of other devices are the same as in Example 1. The JV curve of the perovskite photovoltaic module prepared by the slit coating method is shown below. Figure 14 As shown, the photoelectric conversion efficiency reaches 19.72%. Example 7

[0057] The difference between this embodiment and Example 1 is that 4'-methoxy-2-phenylacetophenone was added to the perovskite precursor solution at a concentration of 2.5 mg / ml; the photovoltaic device fabrication method is the same as in Example 1. In this embodiment, the photoluminescence (PL) mapping of the perovskite thin film and the electroluminescence (EL) mapping of the photovoltaic device, regulated by the in-situ reaction of 4'-methoxy-2-phenylacetophenone with elemental iodine, are shown below. Figure 15 and 16 As shown, the in-situ reaction in this embodiment can improve the quality and uniformity of the perovskite film; the JV curve of the device prepared using this film is shown in Figure 1. Figure 17 As shown, the photoelectric conversion efficiency reaches 25.40%. Example 8

[0058] The difference between this embodiment and Example 1 is that 1,2-bis(4-fluorophenyl)ethyl ketone was added to the perovskite precursor solution at a concentration of 2.5 mg / ml; the photovoltaic device fabrication method is the same as in Example 1. In this embodiment, the photoluminescence (PL) mapping of the perovskite thin film and the electroluminescence (EL) mapping of the photovoltaic device, regulated by the in-situ reaction of 1,2-bis(4-fluorophenyl)acetone with iodine, are shown below. Figure 18 and 19 As shown, the in-situ reaction in this embodiment can improve the quality and uniformity of the perovskite film; the JV curve of the device prepared using this film is shown in Figure 1. Figure 20 As shown, the photoelectric conversion efficiency reaches 25.81%. Example 9

[0059] The difference between this embodiment and Embodiment 1 is that the air pressure in the sealed vacuum chamber is controlled to be 500 Pa during the evacuation process; the photovoltaic device fabrication method is the same as in Embodiment 1. The JV curve of the device fabricated using this thin film is shown below. Figure 21 As shown, the photoelectric conversion efficiency reaches 25.13%. Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that no elemental iodine gas is introduced during the gas extraction process; compared with the in-situ reaction of 4-fluorophenylacetophenone with elemental iodine to regulate perovskite nucleation and growth in Example 1, this comparative example only uses 4-fluorophenylacetophenone to regulate the perovskite crystallization process; the photovoltaic device fabrication method is the same as in Example 1. The JV curve of the perovskite photovoltaic device regulated and prepared using only 4-fluorophenylacetophenone is shown in the figure. Figure 22 As shown, the photoelectric conversion efficiency is 24.53%. Comparative Example 2

[0061] The difference between this comparative example and Example 1 is that 4-fluorophenylacetophenone is not added to the perovskite precursor solution; compared with the in-situ reaction of 4-fluorophenylacetophenone with iodine to regulate perovskite nucleation and growth in Example 1, this comparative example only introduces iodine gas to regulate the perovskite crystallization process; the photovoltaic device fabrication method is the same as in Example 1.

[0062] The JV curve of a perovskite photovoltaic device prepared solely by introducing iodine gas is shown below. Figure 23 As shown, the photoelectric conversion efficiency is 24.43%. Comparative Example 3

[0063] The difference between this comparative example and Example 1 is that the concentration of 4-fluorophenylacetophenone added to the perovskite precursor solution is 50 mg / ml; the photovoltaic device fabrication method is the same as in Example 1. Figure 24 The JV curve of the perovskite photovoltaic device prepared using high-concentration 4-fluorophenylacetophenone is shown, with a photoelectric conversion efficiency of 20.88%. Comparative Example 4

[0064] The difference between this comparative example and Example 1 is that the concentration of the iodine solution is 8 mg / ml; the photovoltaic device fabrication method is the same as in Example 1. Figure 25 The JV curve of the perovskite photovoltaic device prepared by introducing high concentration of iodine gas shows a photoelectric conversion efficiency of 21.82%.

[0065] The embodiments of this invention utilize a vacuum method for preparation, leveraging the in-situ reaction between organic molecules containing active hydrogen and halogen elements to regulate the nucleation and growth process of perovskite. This promotes high-quality, uniform, and dense film formation, inhibits the formation of fluorescence quenching centers during perovskite crystallization, and breaks the vicious cycle of "vacancy defects—ion migration—halogen element regeneration." Simultaneously, photovoltaic devices with perovskite thin films achieve a photoelectric conversion efficiency as high as 26.57%, with significantly improved stability; the device exhibits thermal stability up to 7000 hours at 85 degrees Celsius. This technical solution is highly suitable for the large-scale preparation and production of large-area, flexible perovskite thin films and photovoltaic devices.

[0066] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A metal halide perovskite thin film, characterized in that, The perovskite thin film is prepared by adding an organic additive containing active hydrogen to a perovskite precursor solution, and then further introducing a halogen element into the wet film formed by the solution to undergo an in-situ reaction.

2. The perovskite thin film according to claim 1, characterized in that, The metal halide perovskite is an ABX3 type three-dimensional perovskite or (A′)2A n-1 B n X 3n+1 Quasi-two-dimensional perovskite, wherein A′ is a long-chain organic cation and A is CH3NH3. + HC(NH2)2 + C(NH2)3 + Cs + and Rb + At least one of the following, B is at least one of a Group IV main metal ion or a transition metal ion, and X is Cl. - ,Br - I - At least one of them.

3. The perovskite thin film according to claim 2, characterized in that, The ABX3 type three-dimensional perovskite precursor solution was obtained by dissolving AX and BX2 in a polar solvent at a molar ratio of 0.8~1.5:0.8~1.5; the (A′)2A n-1 B n X 3n+1 The quasi-two-dimensional perovskite precursor solution was obtained by dissolving A′X, AX and BX2 in a polar solvent at a molar ratio of 0.01~10:0.8~1.5:0.8~1.

5. The concentration of the precursor solution is 0.5~2.5 mol / L; The concentration of the organic additive containing active hydrogen in the precursor solution is 0.5~30 mg / ml.

4. The perovskite thin film according to claim 1, characterized in that, The α-position of the active hydrogen in the organic additive is a group with electron-withdrawing or conjugated properties.

5. The perovskite thin film according to claim 1, characterized in that, The organic additive containing active hydrogen is 4-fluorophenylacetophenone, 1,2-bis(4-fluorophenyl)acetophenone, 4'-methoxy-2-phenylacetophenone, 2-(4-fluorophenyl)acetophenone, benzoylacetone, dibenzoylmethane, 4-chlorophenylbenzyl ketone, 1,3-bis(4-fluorophenyl)propane-1,3-dione, 1-(4-chlorophenyl)-2-(3,4-difluorophenyl)ethane-1-one, 1-(4-chlorophenyl)-2-(4-fluorophenyl)ethane-1-one, 1-(4-fluorophenyl)-1,3-butanedione, 4,4,4-trifluoro-1-(4-fluorophenyl)butane-1,3-dione, 4,4,4-trifluoro-1-(4-methoxyphenyl)acetophenone, etc. At least one of the following: (4-nitrobenzoyl)-1,3-butanedione, methyl (4-nitrobenzoyl)pyruvate, 1,3-indanedion, 4,5,6,7-tetrachloroindan-1,3-dione, 4-nitro-1H-indan-1,3(2H)-dione, 1H-cyclopenta[b]naphthalene-1,3(2H)-dione, symmetric indarsen-1,3,5,7(2H,6H)-tetraone, 1-(4-fluorophenyl)-3-(2-hydroxyphenyl)propane-1,3-dione, 1-(3-nitrophenyl)-1,3-butanedione, 1,3-bis(4-chlorophenyl)-1,3-propanedione, and 1-(4-chlorophenyl)-3-(2-hydroxyphenyl)propane-1,3-dione.

6. A method for preparing a perovskite thin film according to any one of claims 1-5, characterized in that, The preparation method involves obtaining a wet film using a vacuuming method, and then subjecting the obtained wet film to high-temperature annealing to obtain a perovskite thin film. The evacuation method includes placing a liquid film formed by the precursor solution in a vacuum chamber, and introducing halogen elemental gas into the vacuum chamber during the evacuation phase to cause an in-situ reaction. The precursor solution forms a liquid film by spin coating or blade coating.

7. The preparation method according to claim 6, characterized in that, The halogen gas exists in solution form before volatilization; the solute in the solution is at least one of Cl2, Br2, and I2. The concentration of the halogen element is 0.01~5 mg / ml.

8. The preparation method according to claim 7, characterized in that, The solvent of the solution is a polar solvent and / or a non-polar solvent; The polar solvent is at least one selected from N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone; The nonpolar solvent is at least one of chlorobenzene, ethyl acetate, toluene, and anisole.

9. The preparation method according to claim 6, characterized in that, The pressure in the vacuum chamber during the evacuation process is 1~1000Pa.

10. A photovoltaic device having a perovskite thin film according to any one of claims 1-5, or having a perovskite thin film prepared by the preparation method according to any one of claims 6-9, characterized in that, It includes a substrate layer, an electrode layer, an electrode modification layer, a hole transport-electron blocking layer, an electron transport-hole blocking layer, and a functional layer; The functional layer includes a perovskite thin film.

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