Perovskite Thin Films, Their Preparation Methods and Applications

Abstract

This invention provides a semi-transparent perovskite thin film, wherein the chemical formula of the perovskite material is FA. 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3, wherein FA is formamidin and MA is methylamine; the perovskite material is doped with 5-bromoacetyl-2-hydroxybenzamide. The perovskite material provided by this invention utilizes the amide groups in 5-bromoacetyl-2-hydroxybenzamide to react with halogens and uncoordinated Pb, respectively. 2+ Ions form hydrogen bonds and coordinate bonds, and the hydroxyl and acetyl groups in 5-bromoacetyl-2-hydroxybenzamide also interact with the perovskite, thereby regulating the crystallization kinetics of the perovskite, providing more uniform nucleation sites, resulting in a faster nucleation rate and a slower crystal growth rate. This leads to perovskite crystal films with high crystallinity, large grain size, and no pores. This invention also provides a method for preparing the aforementioned translucent perovskite solar cell and its applications.

Description

Technical Field

[0001] This invention belongs to the field of solar cells, and specifically relates to a method for preparing perovskite thin films. Background Technology

[0002] Semi-transparent solar cells have emerged as a promising new type of photovoltaic technology, with enormous application potential in areas such as power-generating windows, building-integrated photovoltaics (BIPV), and tandem solar cells. Developed based on traditional solar cells, semi-transparent solar cells not only maximize the collection of sunlight for power generation but also allow unabsorbed light to pass through, achieving a light-transmitting effect or further utilizing this light to power the back electrode. A semi-transparent solar cell mainly consists of a rigid or flexible transparent conductive substrate, a hole transport layer, a photoactive layer, an electron transport layer, and a transparent back electrode. The photoactive layer primarily includes organic semiconductors, organic dyes, and halide perovskite materials.

[0003] In recent years, halide perovskites have been widely used in constructing semi-transparent solar cells due to their advantages such as tunable bandgap, high absorption coefficient, and low manufacturing cost. In practical applications, semi-transparent perovskite solar cells (ST-PSCs) need to simultaneously possess high efficiency and high transparency. Reducing the thickness of the perovskite film can achieve the semi-transparency characteristic of the device. However, as the film thickness decreases, the light absorption capacity of the perovskite active layer weakens, reducing the solar cell current. J SC This leads to a sharp drop in the photoelectric conversion efficiency (PCE) of the battery (Adv. Mater. 2023, 35, 2206574). Therefore, there is a trade-off between the efficiency and transmittance of perovskite films. Furthermore, thin perovskite films with semi-transparent properties (less than 200 nm) and thicker perovskite films (400-600 nm) exhibit different crystallization kinetics. Specifically, the research paper (Adv. Funct. Mater. 2023, 230741, ...) https: / / doi.org / 10.1002 / adfm.202307471)This study points out that perovskite films with a thickness of less than 200 nm exhibit rapid nucleation and crystal growth rates during crystallization, leading to low crystallinity, smaller grain size, increased grain boundaries, and consequently, more defects. Furthermore, a research paper (ACS Energy Lett. 2024, 9, 6, 2936) indicates that because perovskite films grow from bottom to top on the substrate, thinner films are more prone to forming physical defects (such as pores) during crystallization compared to thicker films. Therefore, the fabrication of high-quality, semi-transparent perovskite films is crucial for achieving high-performance semi-transparent solar cells. Thus, developing a method for fabricating semi-transparent perovskite films with low defect density, high crystallinity, and no pores has become an urgent problem to be solved. Summary of the Invention

[0004] The first objective of this invention is to provide a method for preparing a perovskite thin film with low thickness (<200 nm), no pores, low defect density, and high crystallinity.

[0005] The second objective of this invention is to provide a method for preparing the perovskite thin film.

[0006] A third object of the present invention is to provide a solar cell comprising the perovskite thin film.

[0007] A fourth object of the present invention is to provide an application of the perovskite thin film in a solar cell.

[0008] This invention is achieved through the following technical solution:

[0009] A perovskite thin film, comprising

[0010] Perovskite material, its chemical formula is FA 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3, where FA is CH(NH2)2 and MA is CH3NH2; and

[0011] 5-Bromoacetyl-2-hydroxybenzamide, as a modifier, is used to regulate the crystallization kinetics of the perovskite material;

[0012] In the solution of the raw materials used to prepare the perovskite material, the concentration of 5-bromoacetyl-2-hydroxybenzamide is 2.5-3.5 mg / mL, the concentration of CsI is 5.0 mg / mL, the concentration of methyl bromide is 6.5 mg / mL, the concentration of formamidinium iodide is 53.0 mg / mL, the concentration of lead bromide is 42.5 mg / mL, and the concentration of lead iodide is 134.0 mg / mL.

[0013] The thickness of the perovskite film is less than 200 nm.

[0014] The method for preparing the perovskite thin film includes the following steps:

[0015] Cesium iodide (CsI), methyl bromide, formamidine iodoformide, lead bromide, and lead iodide were dissolved in an organic solvent, and then 5-bromoacetyl-2-hydroxybenzamide was added to obtain a precursor solution.

[0016] The precursor solution was dropped onto the substrate surface and spin-coated. Ten seconds before the end of the spin-coating, the antisolvent was dropped onto the substrate surface with the precursor solution spin-coated. Finally, the substrate was heated and annealed for 30-60 minutes to obtain a perovskite film.

[0017] The organic solvent includes dimethylformamide and / or dimethyl sulfoxide;

[0018] The volume ratio of dimethylformamide to dimethyl sulfoxide is 4:1;

[0019] The substrate comprises indium tin oxide glass;

[0020] The heating temperature is 60°C;

[0021] The annealing time is 30-60 minutes.

[0022] The spin coating includes a first spin coating and a second spin coating;

[0023] The first spin coating speed is 1000 r / m, and the time is 40 s;

[0024] The second spin coating speed is 3000 r / m, and the time is 20 s;

[0025] A perovskite solar cell comprising the aforementioned perovskite thin film.

[0026] The perovskite solar cell with the perovskite thin film, from bottom to top, includes a transparent conductive glass substrate, a hole transport layer, the perovskite thin film, an electron transport layer, a hole blocking layer, and a back electrode.

[0027] The transparent conductive glass substrate includes ITO glass;

[0028] The hole transport layer includes PTAA;

[0029] The electron transport layer includes C60;

[0030] The hole-blocking layer includes a BCP;

[0031] The back electrode includes Au.

[0032] The method for fabricating the perovskite solar cell includes the following steps:

[0033] After dissolving PTAA in a solvent, a PTAA solution is obtained. The PTAA solution is dropped onto a transparent conductive glass substrate, and the spin coating is performed at a speed of 3000 r / m for 30 s. Then, the substrate is heated to 120℃ and annealed for 20 min.

[0034] A perovskite thin film is loaded onto the surface of a substrate loaded with PTAA using the method described in claim 2;

[0035] An electron transport layer, a hole blocking layer, and a back electrode were sequentially deposited on the surface of a substrate loaded with a perovskite thin film using a vacuum evaporation method.

[0036] The ratio of PTAA to solvent is 2 mg: 1 mL.

[0037] The solvent includes chlorobenzene.

[0038] The perovskite solar cells described above are used for power generation.

[0039] Compared with existing technologies, the present invention brings the following technical effects:

[0040] This invention provides a low-thickness hybrid perovskite active thin film material. By modulating the precursor solution with 5-bromoacetyl-2-hydroxybenzamide (BASA), the crystallization kinetics are controlled, resulting in rapid nucleation and slow growth. This improves the grain size and crystallinity of the perovskite, reduces the defect state density, and eliminates porosity defects in the film. Applying this perovskite thin film to a semi-transparent solar cell, the resulting pin-type solar cell exhibits higher energy conversion efficiency. Attached Figure Description

[0041] Figure 1 The SEM image of the low-thickness perovskite film prepared in Example 1 is shown.

[0042] Figure 2 The SEM image of the low-thickness perovskite film prepared in Comparative Example 1 is shown.

[0043] Figure 3 The cross-sectional SEM image of the low-thickness perovskite thin film prepared in Example 1 is shown.

[0044] Figure 4 The XRD patterns of perovskite films prepared in Example 1 and Comparative Example 1 with and without 5-bromoacetyl-2-hydroxybenzamide are shown.

[0045] Figure 5The UV-Vis spectra of the perovskite films prepared in Example 1 and Comparative Example 1 with and without 5-bromoacetyl-2-hydroxybenzamide are shown. As can be seen from the figure, the film with 5-bromoacetyl-2-hydroxybenzamide has higher absorbance and stronger light absorption capacity, which indicates that the film is denser and free of pores.

[0046] Figure 6 The photoluminescence (PL) spectra of perovskite films prepared in Example 1 and Comparative Example 1 with and without 5-bromoacetyl-2-hydroxybenzamide are shown. As can be seen from the figure, the film with 5-bromoacetyl-2-hydroxybenzamide has a higher emission spectral intensity, indicating that the film is more dense, pore-free, and has a low defect density.

[0047] Figure 7 A schematic diagram of a semi-transparent perovskite solar cell structure is shown; the semi-transparent cell structure, from bottom to top, consists of:

[0048] 1- Transparent conductive glass: Indium tin oxide (ITO) glass;

[0049] 2-Hole transport layer: Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA);

[0050] 3-Perovskite layer: FA 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3, where FA is CH(NH2)2 and MA is CH3NH2

[0051] 4-Electron transport layer: Fullerene C60;

[0052] 5-Hole blocking layer: 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP);

[0053] 6-Metallic back electrode: Gold (Au);

[0054] Figure 8 The current-voltage curves of the semi-transparent perovskite solar cell prepared in Example 4 are shown. Detailed Implementation

[0055] This invention provides a perovskite thin film with a thickness of less than 200 nanometers, which is composed of perovskite material and 5-bromoacetyl-2-hydroxybenzamide. The chemical formula of the perovskite material is FA. 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24)3, where FA is CH(NH2)2 and MA is CH3NH2. In 5-bromoacetyl-2-hydroxybenzamide (abbreviated as BASA, chemical formula C9H8BrNO3), the amino group (-NH2) in the amide group forms a weak interaction with halogens (e.g., I, Br, etc.) via hydrogen bonds (NH…I), and the C=O bond in the amide group interacts with uncoordinated Pb in perovskite. 2+ Ions form coordinate bonds (C=O-Pb); in addition, hydroxyl groups can form hydrogen bonds with halogens (such as I, Br, etc.), and the C=O bond in the acetyl group can also form a hydrogen bond with Pb. 2+ The ions form coordination bonds, resulting in strong interactions. The presence of these hydrogen bonds stabilizes the crystal structure of the perovskite film, leading to larger grain size and higher crystallinity. This allows the crystal structure to remain stable for extended periods under prolonged sunlight exposure. Furthermore, 5-bromoacetyl-2-hydroxybenzamide can passivate lead-related defects (divalent lead and zero-valent metallic lead) in the perovskite film, thus exhibiting high energy conversion efficiency. The addition amount of 5-bromoacetyl-2-hydroxybenzamide is 2.5-3.5 mg / mL, with an optimal concentration of 3.0 mg / mL. When the addition amount is less than 2.5 mg / mL, the molar number of groups in 5-bromoacetyl-2-hydroxybenzamide that form bonds with the perovskite is insufficient, leading to halogen vacancy defects and uncoordinated divalent lead ion defects. When the addition amount is greater than 3.5 mg / mL, the molar number of groups in 5-bromoacetyl-2-hydroxybenzamide that form bonds with the perovskite is sufficient. However, since the boiling point of 5-bromoacetyl-2-hydroxybenzamide is 420.2℃, it will remain in the film after low-temperature annealing, forming point defects and resulting in phase impurity in the film crystals.

[0056] Specifically, the method for preparing the perovskite thin film includes the following steps:

[0057] Cesium iodide (CsI), methyl bromide, formamidine iodide, lead bromide, and lead iodide were dissolved in an organic solvent, and then 5-bromoacetyl-2-hydroxybenzamide was added to obtain a precursor solution.

[0058] The precursor solution was dropped onto the substrate surface and spin-coated. Ten seconds before the end of the spin-coating, the antisolvent was dropped onto the substrate surface with the precursor solution spin-coated. Finally, the substrate was heated and annealed for 30-60 minutes to obtain a perovskite film.

[0059] 5-Bromoacetyl-2-hydroxybenzamide plays a crucial role in the preparation of perovskite thin films. In the precursor solution, 5-Bromoacetyl-2-hydroxybenzamide can form hydrogen bonds with groups in the raw materials. Therefore, it can regulate the crystallization kinetics of the perovskite precursor solution, providing more uniform nucleation sites, accelerating the nucleation rate, and slowing down the crystal growth rate, thereby obtaining translucent perovskite films with large grain size, low defect density, and no pores. Especially when the film thickness is less than 200 nm, without the addition of 5-Bromoacetyl-2-hydroxybenzamide, the film obtained after annealing will contain numerous pores and voids. However, the addition of 5-Bromoacetyl-2-hydroxybenzamide significantly improves the quality of the film.

[0060]

[0061] The organic solvent includes dimethylformamide or a mixture of dimethylformamide and dimethyl sulfoxide (DMSO). The mixed solvent is more effective than the single solvent. This is because DMSO acts as a co-solvent, making the precursor solution more stable. Simultaneously, DMSO chelates with Pb during perovskite crystallization to form an intermediate phase, which helps to obtain crystalline films with higher crystallinity.

[0062] The volume ratio of dimethylformamide to dimethyl sulfoxide is 4:1; the amount of DMSO should be in a suitable ratio. Too little will not play a role in solubilizing and crystallization control, while too much will not be conducive to film formation (because DMSO is more hydrophobic than dimethylformamide (DMF), making it more difficult for the solution to spread on the substrate during spin coating, resulting in lower film coverage).

[0063] The substrate comprises indium tin oxide glass;

[0064] The heating temperature is 60°C; too high a temperature will cause the organic components (FA: CH(NH2)2, MA:CH3NH2) in the perovskite to volatilize.

[0065] The annealing time is 30-60 minutes.

[0066] The spin coating includes a first spin coating and a second spin coating. The first spin coating is performed at a low speed of 1000 r / m, which mainly serves to spread the solution and prevent the solvent from evaporating quickly. The second spin coating is performed at a higher speed of 3000 r / m, and the anti-solvent chlorobenzene is added dropwise to quickly replace DMF and DMSO in the perovskite precursor, resulting in rapid crystallization.

[0067] The first spin coating speed is 1000 r / m, and the time is 40 s;

[0068] The second spin coating speed is 3000 r / m, and the time is 20 s;

[0069] A perovskite solar cell comprising the aforementioned perovskite thin film.

[0070] The perovskite solar cell with the perovskite thin film, from bottom to top, includes a transparent conductive glass substrate, a hole transport layer, the perovskite thin film, an electron transport layer, a hole blocking layer, and a back electrode.

[0071] The transparent conductive glass substrate includes ITO glass; those skilled in the art will understand that the transparent conductive glass substrate can also be FTO, but semi-transparent solar cells typically use ITO.

[0072] Preferably, the hole transport layer comprises PTAA; those skilled in the art will understand that the hole transport layer may also be made of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) or nickel oxide (NiO).

[0073] The electron transport layer comprises C60; those skilled in the art will understand that the electron transport layer can also be made of methyl [6,6]-phenyl C61 butyrate (PC). 61 BM)

[0074] The hole-blocking layer includes a BCP;

[0075] The back electrode includes Au. Those skilled in the art will understand that the back electrode can also be Ag (20 nm), Ag (20 nm) / MoO3 (10 nm), Cu (5 nm) / Ag (15 nm), etc.

[0076] By adjusting the preparation parameters and fixing the precursor solution concentration and spin coating process parameters (rotation speed, acceleration, and spin coating time), the thickness of the perovskite film can be precisely controlled to be less than 200 nm.

[0077] The method for fabricating the perovskite solar cell includes the following steps:

[0078] After dissolving PTAA in a solvent, a PTAA solution is obtained. The PTAA solution is dropped onto a transparent conductive glass substrate, and the spin coating is performed at a speed of 3000 r / m for 30 s. Then, the substrate is heated to 120℃ and annealed for 20 min.

[0079] The method described above is used to load perovskite thin films onto the surface of a substrate loaded with PTAA;

[0080] An electron transport layer, a hole blocking layer, and a back electrode were sequentially deposited on the surface of a substrate loaded with a perovskite thin film using a vacuum evaporation method.

[0081] The ratio of PTAA to solvent is 2 mg: 1 mL;

[0082] The solvent includes chlorobenzene. Those skilled in the art will understand that common organic solvents can be used to achieve this invention. Specifically, dichlorobenzene, etc., may be selected.

[0083] Because the perovskite solar cells described above have high energy conversion efficiency, they can be used for power generation.

[0084] The present invention will be further described below with reference to specific embodiments.

[0085] The 5-bromoacetyl-2-hydroxybenzamide used in this invention is manufactured by Thermo Scientific and purchased from Bailingwei Technology Co., Ltd.

[0086] Example 1

[0087] 5.0 mg of cesium iodide (CsI), 6.5 mg of methyl bromide (CH3NH3Br, MABr), 53.0 mg of formamidine iodoformide (CH(NH2)2I, FAI), 42.5 mg of lead bromide (PbBr2), and 134.0 mg of lead iodide (PbI2) were dissolved in 1 mL of a mixed solvent of dimethylformamide (C3H7NO, DMF) and dimethyl sulfoxide (C2H6OS, DMSO) at a volume ratio of 4:1. 3 mg of 5-bromoacetyl-2-hydroxybenzamide was added to the solution. The solution was placed on a heating plate and stirred at 60 °C for 4 h. After complete dissolution, the precursor solution was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) filter.

[0088] The precursor solution was dropped onto an indium tin oxide (ITO) glass substrate using a pipette. A spin coater was set with two parameters (1,000 rpm for 40 s, 3,000 rpm for 20 s). Ten seconds before the end of the spin coat, diethyl ether was dropped onto the perovskite film as an antisolvent. The perovskite film was then transferred to a heating plate and annealed at 80-110 °C for 30-60 min to obtain the perovskite film.

[0089] Example 2

[0090] 5.0 mg of cesium iodide (CsI), 6.5 mg of methyl bromide (CH3NH3Br, MABr), 53.0 mg of formamidine iodoformide (CH(NH2)2I, FAI), 42.5 mg of lead bromide (PbBr2), and 134.0 mg of lead iodide (PbI2) were dissolved in 1 mL of a mixed solvent of dimethylformamide (C3H7NO, DMF) and dimethyl sulfoxide (C2H6OS, DMSO) at a volume ratio of 4:1. 2.5 mg of 5-bromoacetyl-2-hydroxybenzamide was added to the solution. The solution was placed on a heating plate and stirred at 60 °C for 4 h. After complete dissolution, the precursor solution was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) filter.

[0091] The precursor solution was dropped onto an indium tin oxide (ITO) glass substrate using a pipette. A spin coater was set with two parameters (1,000 rpm for 40 s, 3,000 rpm for 20 s). Ten seconds before the end of the spin coat, diethyl ether was dropped onto the perovskite film as an antisolvent. The perovskite film was then transferred to a heating plate and annealed at 80-110 °C for 30-60 min to obtain the perovskite film.

[0092] Example 3

[0093] 5.0 mg of cesium iodide (CsI), 6.5 mg of methyl bromide (CH3NH3Br, MABr), 53.0 mg of formamidine iodoformide (CH(NH2)2I, FAI), 42.5 mg of lead bromide (PbBr2), and 134.0 mg of lead iodide (PbI2) were dissolved in 1 mL of a mixed solvent of dimethylformamide (C3H7NO, DMF) and dimethyl sulfoxide (C2H6OS, DMSO) at a volume ratio of 4:1. 3.5 mg of 5-bromoacetyl-2-hydroxybenzamide was added to the solution. The solution was placed on a heating plate and stirred at 60 °C for 4 h. After complete dissolution, the precursor solution was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) filter.

[0094] The precursor solution was dropped onto an indium tin oxide (ITO) glass substrate using a pipette. A spin coater was set with two parameters (1,000 rpm for 40 s, 3,000 rpm for 20 s). Ten seconds before the end of the spin coat, diethyl ether was dropped onto the perovskite film as an antisolvent. The perovskite film was then transferred to a heating plate and annealed at 80-110 °C for 30-60 min to obtain the perovskite film.

[0095] Comparative Example 1

[0096] 5.0 mg of cesium iodide (CsI), 6.5 mg of methyl bromide (CH3NH3Br, MABr), 53.0 mg of formamidine iodocarbamate (CH(NH2)2I, FAI), 42.5 mg of lead bromide (PbBr2), and 134.0 mg of lead iodide (PbI2) were dissolved in 1 mL of a mixed solvent of dimethylformamide (C3H7NO, DMF) and dimethyl sulfoxide (C2H6OS, DMSO), with a volume ratio of 4:1. The solution bottle was placed on a heating plate and stirred at 60 °C for 4 h. After complete dissolution, the precursor solution was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) filter.

[0097] The precursor solution was dropped onto an indium tin oxide (ITO) glass substrate using a pipette. A spin coater was set with two parameters (1,000 rpm for 40 s, 3,000 rpm for 20 s). Ten seconds before the end of the spin coat, diethyl ether was dropped onto the perovskite film as an antisolvent. The perovskite film was then transferred to a heating plate and annealed at 80-110 °C for 30-60 min to obtain the perovskite film.

[0098] Example 4

[0099] This embodiment provides a method for preparing the aforementioned semi-transparent perovskite solar cell.

[0100] The semi-transparent perovskite solar cell is a pin-type semi-transparent solar cell, and its device structure is ITO / PTAA / perovskite / C60 / BCP / Au (see...). Figure 4 The structure consists of an indium tin oxide (ITO) transparent conductive glass substrate, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) hole transport layer, perovskite as the active layer, fullerene C60 as the electron transport layer, 2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline (BCP) as the hole blocking layer, and gold (Au) as the back electrode.

[0101] Its preparation process includes the following steps:

[0102] ITO glass cleaning: Thoroughly clean both sides of the substrate with glass cleaner, then place the ITO substrate into a cleaning rack and immerse it sequentially in distilled water, acetone, and isopropanol. After each immersion in an ultrasonic cleaner, ultrasonically clean for 15 minutes. Finally, dry the ITO substrate in an electrically heated drying oven. Before assembling the battery, treat the ITO glass with ultraviolet-ozone for 15 minutes.

[0103] Preparation of the hole transport layer: 2 mg of PTAA solid powder was weighed and dissolved in 1 mL of chlorobenzene (CB) solvent. After stirring at room temperature, a clear PTAA solution was obtained. Subsequently, an appropriate amount of PTAA solution was dropped onto an ITO conductive glass substrate, and spin-coated at 3000 rpm for 30 s. Then, it was annealed at 120 °C for 20 min on a constant temperature heating plate.

[0104] A semi-transparent perovskite film was prepared on PTAA according to the method in Example 1.

[0105] Electron transport layer, hole blocking layer, and gold electrode are deposited using vacuum evaporation technology: The vacuum coating machine needs to deposit films including C60, BCP, and Au electrodes. Appropriate amounts of C60 and BCP powders are placed in beam source furnace 1 and beam source furnace 2, respectively. After closing the coating machine chambers, a mechanical pump is used for rough evaporation to reduce the internal pressure of the chambers from atmospheric pressure to below 5 Pa. After the rough evaporation is closed, the pre-stage valve, baffle valve, and molecular pump are opened to continue fine evaporation. When the chamber pressure reaches 5 × 10⁻⁶ Pa... -4 After the pressure drops below 500 Pa, the temperature of beam source furnace 1 and beam source furnace 2 are programmed to meet the sublimation conditions of C60 and BCP under high vacuum. When the temperature of beam source furnace 1 reaches about 520°C, the film thickness gauge senses the material output (0.2 Å / s) through the crystal oscillator probe inside the chamber, and the mask is opened to begin evaporation. The thickness of the entire film is also tracked using the film thickness gauge. When the C60 film thickness reaches 20 nm, the mask is closed. Beam source furnace 2 is operated to raise the temperature to about 150°C to complete the evaporation of the BCP barrier layer, with a thickness of 7 nm. The sample is then removed by venting and transferred to a mask with an electrode pattern for Au electrode evaporation. The above roughing and fine evaporation steps are repeated until the chamber pressure reaches 5 × 10⁻⁶. -4 After the voltage drops below Pa, the voltage is applied to make the Au deposition rate about 0.5 Å / s. Once the Au electrode thickness reaches 20 nm, the voltage is reduced to 0V, the gas is exhausted, and the device is removed, completing the battery assembly.

[0106] Example 5

[0107] The difference from Example 4 is that a semi-transparent perovskite film is prepared on PTAA according to the method in Example 2.

[0108] Example 6

[0109] The difference from Example 4 is that a semi-transparent perovskite film is prepared on PTAA according to the method in Example 3.

[0110] Comparative Example 2

[0111] The difference from Example 4 is that a semi-transparent perovskite film was prepared on PTAA according to the method in Comparative Example 1.

[0112] The parameters of the solar cells prepared in Examples 4-6 and Comparative Example 2 are shown. The efficiency conversion formula is as follows:

[0113] Efficiency (PCE) = Short-circuit current (Jsc) × Open-circuit voltage (Voc) × Quality factor (FF).

[0114] Table 1

[0115]

[0116] As can be seen from Table 1, the battery efficiency is significantly improved after adding 5-bromoacetyl-2-hydroxybenzamide.

Claims

1. A perovskite thin film, characterized in that: include Perovskite material, its chemical formula is FA 0.8 MA 0.15 Cs 0.05 Pb(I 0.76 Br 0.24 )3, where FA is NH2CH=NH, and MA is CH3NH2; and 5-Bromoacetyl-2-hydroxybenzamide, as a modifier, is used to regulate the crystallization kinetics of the perovskite material; In the solution of the raw materials used to prepare the perovskite material, the concentration of 5-bromoacetyl-2-hydroxybenzamide is 2.5-3.5 mg / mL, the concentration of CsI is 5.0 mg / mL, the concentration of methyl bromide is 6.5 mg / mL, the concentration of formamidinium iodide is 53.0 mg / mL, the concentration of lead bromide is 42.5 mg / mL, and the concentration of lead iodide is 134.0 mg / mL. The thickness of the perovskite film is less than 200 nm.

2. The method for preparing perovskite thin films according to claim 1, characterized in that: Includes the following steps: Cesium iodide (CsI), methyl bromide, formamidine iodoformide, lead bromide, and lead iodide were dissolved in an organic solvent, and then 5-bromoacetyl-2-hydroxybenzamide was added to obtain a precursor solution. The precursor solution was dropped onto the substrate surface and spin-coated. Ten seconds before the spin-coating was completed, the antisolvent was dropped onto the substrate surface with the precursor solution spin-coated. Finally, the substrate was heated and annealed for 30-60 minutes to obtain a perovskite film.

3. The method for preparing perovskite thin films according to claim 2, characterized in that: The organic solvent includes dimethylformamide; or The organic solvents include dimethylformamide and dimethyl sulfoxide; The volume ratio of dimethylformamide to dimethyl sulfoxide is 9:1, 4:1, or 7:

3. The substrate comprises indium tin oxide glass; The heating temperature is 30-80℃; The annealing time is 30-60 minutes.

4. The method for preparing perovskite thin films according to claim 2, characterized in that: The spin coating includes a first spin coating and a second spin coating; The first spin coating speed is 500-1500 r / m, and the time is 30-50 s; The second spin coating speed is 3000-5000 r / m, and the time is 10-30 s.

5. A perovskite solar cell comprising the perovskite thin film of claim 1.

6. The perovskite solar cell with a perovskite thin film as described in claim 5, characterized in that: From bottom to top, it includes a transparent conductive glass substrate, a hole transport layer, the perovskite thin film, an electron transport layer, a hole blocking layer, and a back electrode.

7. The perovskite solar cell with a perovskite thin film as described in claim 6, characterized in that: The transparent conductive glass substrate includes ITO glass; The hole transport layer includes PTAA; The electron transport layer includes C60; The hole-blocking layer includes a BCP; The back electrode includes Au.

8. The method for preparing a perovskite solar cell as described in claim 7, characterized in that: Includes the following steps: After dissolving PTAA in a solvent, a PTAA solution is obtained. The PTAA solution is dropped onto a transparent conductive glass substrate and spin-coated at a speed of 2000-3000 r / m for 20-35 s. Then, it is heated to 100-120℃ and annealed for 10-20 min. A perovskite thin film is loaded onto the surface of a substrate loaded with PTAA using the method described in claim 2. An electron transport layer, a hole blocking layer, and a back electrode were sequentially deposited on the surface of a substrate loaded with a perovskite thin film using a vacuum evaporation method.

9. The method for preparing a perovskite solar cell as described in claim 8, characterized in that: The ratio of PTAA to solvent is 2 mg: 1 mL; The solvent includes chlorobenzene.

10. The application of the perovskite solar cell as described in claim 6, characterized in that: It is used in power generation.

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