Perovskite thin film and preparation method and application thereof

Abstract

The application discloses a perovskite thin film and a preparation method and application thereof, diethyl sulfate micromolecules are dissolved in a perovskite precursor solution according to a certain concentration, perovskite crystallization is delayed, perovskite crystal grains are increased, and the photoelectric performance of a solar cell device based on the perovskite thin film is improved. The solar cell device comprises a substrate, a transparent electrode, a first charge transport layer, a perovskite polycrystal thin film layer, a second charge transport layer and a top electrode which are sequentially stacked. The method can significantly increase the perovskite thin film crystal grains, improve the perovskite thin film crystallization quality, is simple in process, low in requirement for equipment, high in stability and repeatability, low in dependence on environment and low in cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar cells, and particularly relates to a perovskite thin film and a preparation method and application thereof. BACKGROUND

[0002] Today, with the continuous breakthroughs in photovoltaic technology, metal halide perovskite solar cells are causing an unprecedented revolution in the photovoltaic field due to their excellent photoelectric conversion efficiency, excellent light capture characteristics, and relatively low preparation cost. The core of this technology lies in the perovskite thin film light-absorbing layer, which has a unique ABX3 crystal structure (where A is usually occupied by alkali metal ions or organic cations, B is a transition metal ion, and X is a halogen ion), giving perovskite materials excellent photoelectric properties. In recent years, the photoelectric conversion efficiency of perovskite solar cells under laboratory conditions has far exceeded that of traditional thin-film solar cells, which is a milestone achievement indicating that perovskite technology is gradually becoming the core force of the photovoltaic industry and leading the future development of photovoltaic technology.

[0003] Although the photoelectric conversion efficiency of perovskite solar cells has made great progress, their long-term stability remains a major challenge in the current research field. The core light-absorbing layer perovskite will degrade during device operation when exposed to external factors such as light, heat, moisture, and oxygen. These degradations often start preferentially at the defects of the perovskite thin film and trigger a chain reaction, leading to poor quality of the perovskite thin film, reduced carrier extraction and transport efficiency, and further causing the efficiency of the perovskite solar cell to decay. Therefore, how to prepare high-quality perovskite thin films is crucial for improving the long-term stability of solar cells.

[0004] Defects in perovskite thin films are mainly divided into intrinsic defects and extrinsic defects. Intrinsic defects are defects that occur during the formation of perovskite thin films due to their own structural characteristics. These defects mainly include: point defects: caused by the absence of A-site ions, B-site ions, and oxygen ions. In perovskite thin films, the absence or replacement of ions can lead to incomplete lattice structure, resulting in point defects. Domain walls: domain walls formed between domains of different orientations are also one of the common intrinsic defects in perovskite thin films. Extrinsic defects are defects induced by external factors. These defects include: during the crystallization process of the thin film, if the lattice arrangement is not perfect or the atomic period is disturbed, it can lead to the formation of high-density defects; during the preparation and subsequent processing of perovskite thin films, if they are exposed to external environments (such as water, light, oxygen, etc.), degradation reactions can occur, leading to deformation, stretching, and twisting of the crystal, and further forming defects. The most effective means to control and passivate defects in perovskite thin films is in-situ defect control of the thin film body.

[0005] A method for preparing high-quality perovskite films in the prior art introduces small molecules at the buried interface for modification, providing a better template for perovskite growth, but this method often requires additional operation steps in the preparation process, which is not conducive to commercial production.

[0006] Another method for preparing high-quality perovskite films in the prior art also introduces some small molecules of long-chain organic ammonium salt on the surface of perovskite for post-treatment, thereby passivating the surface defects of the perovskite film. This method, on the one hand, introduces additional operation steps, which is not conducive to commercial production; on the other hand, the post-treatment after the completion of the crystallization of the perovskite film is quite limited in passivating the defects in the bulk phase of the perovskite film, and it is difficult to effectively improve the crystallization quality of the perovskite film. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a perovskite film, a preparation method and an application thereof, which solves the technical problem in the prior art that the high-quality preparation method for the light-absorbing layer in the perovskite solar cell device cannot be adapted to different preparation methods, and the commonly used passivation strategy often requires additional operation steps, and it is difficult to effectively passivate the bulk phase defects of the perovskite film, by doping small molecules into the perovskite precursor solution, making them preferentially combine with PbI2 in the precursor solution, delaying the crystallization of the perovskite film, and realizing the preparation of large-grain high-quality perovskite films. This not only improves the stability of the perovskite layer, but also improves the efficiency and stability of the solar cell device.

[0008] The present application adopts the following technical solutions:

[0009] A perovskite film preparation method, diethyl sulfate small molecules are dissolved in a perovskite precursor solution, the concentration of diethyl sulfate small molecules in the perovskite precursor solution is 3-15 mg / mL, then the perovskite precursor solution containing small molecules is coated on a substrate, and a perovskite film is obtained after annealing treatment.

[0010] Preferably, the diethyl sulfate small molecule adopts diethyl sulfate, and the molecular structure is C4H 10 O4S.

[0011] Preferably, the annealing temperature is 50-150 DEG C, and the annealing time is 5-20 min.

[0012] Preferably, the perovskite material used in the perovskite precursor solution includes formamidinium hydroiodide, cesium iodide, lead iodide and lead bromide.

[0013] Preferably, the perovskite precursor solution containing small molecules is coated on the substrate by spin coating, spraying, soaking or blade coating process.

[0014] Another technical solution of the present application is a perovskite thin film.

[0015] Another technical solution of the present application is a solar cell device, comprising a substrate, a transparent electrode, an electron transport layer, a perovskite thin film layer, a hole transport layer and a top electrode stacked in order from bottom to top; the perovskite thin film is prepared according to the method, and the thickness of the perovskite thin film layer is 300-600 nm.

[0016] Preferably, the transparent electrode is made of inorganic material or organic conductive polymer, the inorganic material is one metal oxide of indium tin oxide, zinc oxide or tin oxide, or is one metal of gold, copper, silver or zinc; the organic conductive polymer is polythiophene, polystyrene sulfonate or polyaniline.

[0017] Preferably, the electron transport layer is made of tin oxide, titanium oxide, zinc oxide, fullerene or fullerene derivative.

[0018] Preferably, the hole transport layer is made of nickel oxide, 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, poly-3-hexylthiophene or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine].

[0019] Compared with the prior art, the present application has at least the following beneficial effects:

[0020] A perovskite thin film preparation method, diethyl sulfate small molecules in the perovskite precursor solution can form a relatively strong network structure during the annealing process. This network structure helps to enhance the mechanical strength and flexibility of the perovskite thin film, especially when the thin film is applied to flexible electronic devices (such as flexible solar cells), which has important advantages; by controlling the concentration of diethyl sulfate small molecules (3-15 mg / mL), the surface structure and interface properties of the thin film can be controlled, thereby affecting the photoelectric properties of the perovskite material. For example, an appropriate amount of small molecules may help to improve the carrier transport rate or reduce the interface defect density, thereby improving the photoelectric conversion efficiency of the perovskite solar cell; adding diethyl sulfate small molecules to the perovskite precursor solution and forming a perovskite thin film through coating and annealing process can simplify the traditional perovskite thin film preparation method. This method may reduce the dependence on complex additives or external equipment, while improving the quality of the thin film by optimizing the solution composition and process conditions; by introducing diethyl sulfate small molecules, the present application not only improves the mechanical strength, chemical stability and photoelectric properties of the perovskite thin film, but also simplifies the preparation process and gives the thin film wider application potential. These advantages help to improve the application effect of perovskite materials in optoelectronics, electronics and other fields

[0021] Furthermore, by introducing the small molecule diethyl sulfate into the perovskite precursor solution, the mechanical strength, chemical stability, charge transfer performance and photoelectric conversion efficiency of the perovskite film can be improved, while simplifying the preparation process, reducing costs, and giving the film more controllable functions.

[0022] Furthermore, the perovskite material is formamidine hydroiodide, cesium iodide, lead iodide or lead bromide, which can form an efficient perovskite structure, provide high photoelectric conversion efficiency, and improve the environmental stability of perovskite solar cells, especially in high humidity and high temperature environments, slowing down the degradation of the perovskite layer.

[0023] A perovskite film with excellent light absorption properties that can effectively absorb visible light. By adjusting the band gap of the perovskite material through different formulations, the film can exhibit optimal light absorption capacity under different lighting conditions, optimizing the photoelectric performance. It does not require the use of highly toxic solvents or complex high-temperature treatments and is relatively more environmentally friendly.

[0024] A solar cell device, in which the perovskite film can provide appropriate light transmittance and reflectivity, helps reduce interface defects and carrier recombination losses, thereby improving the overall performance and stability of the solar cell. It has the advantages of high photoelectric conversion efficiency, good stability, long service life, low-cost production and wide application potential.

[0025] In summary, the method of the present invention can significantly increase the grain size of the perovskite film, improve the crystallization quality of the perovskite film, has a simple process, low equipment requirements, high stability and repetition rate, low dependence on the environment, and low cost.

[0026] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 Schematic diagram of perovskite solar device;

[0029] Figure 2 These are scanning electron microscope images of Example 1 before and after doping with small molecules;

[0030] Figure 3 The voltage-current density curves of the devices prepared with the modified and unmodified perovskite layers in Example 1 are shown;

[0031] Figure 4 These are scanning electron micrographs of Example 2 before and after doping with small molecules;

[0032] Figure 5 The voltage-current density curves of the devices prepared with the modified and unmodified perovskite layers in Example 2 are shown;

[0033] Figure 6 These are scanning electron micrographs of Example 3 before and after doping with small molecules;

[0034] Figure 7 The voltage-current density curves of the devices prepared with the modified and unmodified perovskite layers in Example 3 are shown;

[0035] Figure 8 The scanning electron micrographs before and after doping with small molecules;

[0036] Figure 9 A comparison of the voltage-current density curves of devices prepared with modified and unmodified perovskite layers.

[0037] Among them, 1. substrate; 2. transparent electrode; 3. electron transport layer; 4. perovskite thin film layer; 5. hole transport layer; 6. top electrode. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0040] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0041] In the present invention, unless otherwise specified, percentages (%) or parts refer to percentages by weight or parts by weight relative to the composition.

[0042] In the present invention, unless otherwise specified, the components involved or their preferred components can be combined with each other to form a new technical solution.

[0043] In this disclosure, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" are listed herein, and "6-22" is merely an abbreviation for these numerical combinations.

[0044] The "range" disclosed in the present invention is in the form of lower limit and upper limit, which can be one or more lower limits, and one or more upper limits respectively.

[0045] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0046] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the order. Preferably, the reaction method herein is carried out sequentially.

[0047] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0048] The present invention provides a perovskite film, a preparation method and an application thereof. Small molecules are dissolved in a perovskite precursor solution at a certain concentration, which effectively delays the growth of the perovskite film, improves the crystallization quality of the perovskite film, enlarges the perovskite grains, and passivates vacancy defects in the film. At the same time, the photoelectric performance and stability of battery devices based on the doped film are significantly improved. The present invention achieves the preparation of high-quality perovskite films by doping specific small molecules into the perovskite precursor solution, improves the device operation stability from within the device, and is conducive to the further development of perovskite solar cells.

[0049] The present invention provides a method for preparing a perovskite thin film, comprising the following steps:

[0050] The diethyl sulfate small molecule is dissolved in the perovskite precursor solution, and the concentration of the diethyl sulfate small molecule is selected to be 3~15mg / mL; the perovskite precursor solution containing the small molecule is then coated on a substrate and subsequently annealed at 50~150℃ for 5~20 minutes to obtain a high-quality perovskite film, delay the crystallization of the perovskite film, improve the crystallization quality of the perovskite film, and improve the photoelectric performance and stability of the perovskite solar cell device.

[0051] Diethyl sulfate small molecule uses diethyl sulfate, the molecular structure is C4H 10 O4S.

[0052] The perovskite material is formamidine hydroiodide, cesium iodide, lead iodide or lead bromide.

[0053] The perovskite precursor solution containing small molecules is coated on the substrate by spin coating, spray coating, immersion, or doctor blade coating process, and the substrate includes a substrate, a transparent electrode, and an electron transport layer.

[0054] Referring to Figure 2 The solar cell device includes a substrate 1, a transparent electrode 2, an electron transport layer 3, a perovskite thin film layer 4, a hole transport layer 5, and a top electrode 6, which are sequentially stacked; and the thickness of the perovskite thin film layer 4 is 300-600 nm.

[0055] The substrate 1 is made of glass or a flexible substrate, and the flexible substrate is made of a polyester or a polythiophene compound.

[0056] The transparent electrode 2 is made of an inorganic material or an organic conductive polymer, and the inorganic material is one of indium tin oxide, zinc oxide, or tin oxide, or is one of gold, copper, silver, or zinc; and the organic conductive polymer is polythiophene, polystyrene sulfonate, or polyaniline.

[0057] The material of the electron transport layer 3 is tin oxide, titanium oxide, zinc oxide, fullerene, or a fullerene derivative.

[0058] The material of the hole transport layer 5 is nickel oxide, 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), poly-3-hexylthiophene (P3HT), or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).

[0059] The material of the top electrode 6 is a metal, and the metal is gold, silver, copper, or aluminum.

[0060] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0061] Embodiment 1

[0062] Referring to Figure 1The perovskite solar device according to the first embodiment of the present invention has the following structure:

[0063] Glass (plastic) substrate / ITO (100 nm) / NiOx (30 nm) / FA 0.8 Cs 0.2 Pb(I 0.65 Br 0.35 )3(350 nm) / C 60 (20 nm) / Ag(120 nm).

[0064] (1) Cleaning of the glass substrate pre-engraved with ITO: The transparent conductive substrate 1 (ITO glass) was cleaned using ethanol, acetone ultrasonication, and deionized water ultrasonication. After cleaning, it was placed under an infrared lamp for drying. The ITO film on the transparent conductive substrate 1 served as the transparent electrode 2 of the device. The square resistance of the ITO film was 15Ω to 30Ω, and the film thickness was 80 to 120nm.

[0065] (2) Preparation of hole transport layer: The dried substrate was treated with UV-ozone for 5-10 minutes, then placed on a spin coater and the prepared NiOx aqueous solution was spin-coated into a film using a static batching method. The spin coater speed was 3000 rpm and the spin coating time was controlled at 45 s. The sample was dried at 150 °C for 20 mins and the thickness was 30 nm.

[0066] (3) Preparation of perovskite layer: 328.46 mg of PbI2, 289.01 mg of PbBr2, 206.40 mg of FAI, and 77.9 mg of CsI were weighed and added to a mixed solution of 0.75 mL of DMF and 0.25 mL of DMSO to form a precursor solution. 3 mg of C4H 10 O4S was added to the precursor solution and stirred overnight. After filtration, it was spin-coated onto the electron transport layer at 4000 rpm for 60 seconds. After the 25th second, 0.5 mL of chlorobenzene was added dropwise to the top of the solution. After spin coating, the substrate was annealed on an 80°C drying oven for 5 minutes. The resulting film thickness was 350 nm. Figure 2 These are scanning electron microscope images before and after doping with small molecules. It can be seen that the grains of the perovskite film are significantly enlarged after doping.

[0067] (4) Preparation of electron transport layer: Place the spin-coated and dried substrate into a vacuum chamber and evaporate C 60 , the evaporation rate of the material film is 0.1 nm / s and the film thickness is 20 nm;

[0068] (5) Preparation of the top electrode: Place the spin-coated and dried substrate into a vacuum chamber and evaporate metallic silver. The evaporation rate of the material film is 0.1 nm / s and the film thickness is 120 nm.

[0069] Figure 3 The voltage-current density curves of devices prepared with modified and unmodified perovskite layers are compared. It can be seen from the figure that the device performance of the device prepared with the treated perovskite layer has been greatly improved: the fill factor has increased from 62% to 65%, and the energy conversion efficiency has increased from 14.65% to 15.52%.

[0070] Example 2

[0071] See also Figure 1 The perovskite solar device according to the first embodiment of the present invention has the following structure:

[0072] Glass (plastic) substrate / ITO (100 nm) / NiOx (30 nm) / FA 0.8 Cs 0.2 Pb(I 0.65 Br 0.35 )3(350nm) / C 60 (20 nm) / Ag(120 nm).

[0073] (1) Cleaning of the glass substrate pre-engraved with ITO: The transparent conductive substrate 1 (ITO glass) was cleaned using ethanol, acetone ultrasonic and deionized water ultrasonic methods, and then placed under an infrared lamp for drying. The ITO film on the transparent conductive substrate 1 served as the transparent electrode 2 of the device. The square resistance of the ITO film was 15Ω to 30Ω, and the film thickness was 80 to 120nm.

[0074] (2) Preparation of hole transport layer: The dried substrate was treated with UV-ozone for 5-10 minutes, then placed on a spin coater and the prepared NiOx aqueous solution was spin-coated into a film using a static batching method. The spin coater speed was 3000 rpm and the spin coating time was controlled at 45 s. The sample was dried at 150 °C for 20 mins to a thickness of 30 nm.

[0075] (3) Preparation of perovskite layer: 328.46 mg of PbI2, 289.01 mg of PbBr2, 206.40 mg of FAI, and 77.9 mg of CsI were weighed and added to a mixed solution of 0.75 mL of DMF and 0.25 mL of DMSO to form a precursor solution. 8 mg of C4H 10O4S was added to the precursor solution and stirred overnight. After filtration, it was spin-coated onto the electron transport layer at 4000 rpm for 60 seconds. After the 25th second, 0.5 mL of chlorobenzene was added dropwise to the top of the solution. After spin coating, the substrate was annealed on a 100°C drying oven for 10 minutes. The resulting film thickness was 350 nm. Figure 4 These are scanning electron microscope images before and after doping with small molecules. It can be seen that the grains of the perovskite film are significantly enlarged after doping.

[0076] (4) Preparation of electron transport layer: Place the spin-coated and dried substrate into a vacuum chamber and evaporate C 60 , the evaporation rate of the material film is 0.1 nm / s and the film thickness is 20 nm;

[0077] (5) Preparation of the top electrode: Place the spin-coated and dried substrate into a vacuum chamber and evaporate metallic silver. The evaporation rate of the material film is 0.1 nm / s and the film thickness is 120 nm.

[0078] Figure 5 The voltage-current density curves of devices prepared with modified and unmodified perovskite layers are compared. It can be seen from the figure that the device performance of the device prepared with the treated perovskite layer has been greatly improved: the fill factor has increased from 62% to 70%, and the energy conversion efficiency has increased from 14.65% to 18.59%.

[0079] Example 3

[0080] See also Figure 1 The perovskite solar device according to the first embodiment of the present invention has the following structure:

[0081] Glass (plastic) substrate / ITO (100 nm) / NiOx (30 nm) / FA 0.8 Cs 0.2 Pb(I 0.65 Br 0.35 )3(350 nm) / C 60 (20 nm) / Ag(120 nm).

[0082] (1) Cleaning of the glass substrate pre-engraved with ITO: The transparent conductive substrate 1 (ITO glass) was cleaned using ethanol, acetone ultrasonication, and deionized water ultrasonication. After cleaning, it was placed under an infrared lamp for drying. The ITO film on the transparent conductive substrate 1 served as the transparent electrode 2 of the device. The square resistance of the ITO film was 15Ω to 30Ω, and the film thickness was 80 to 120nm.

[0083] (2) Preparation of hole transport layer: The dried substrate was treated with UV-ozone for 5-10 minutes, then placed on a spin coater and the prepared NiOx aqueous solution was spin-coated into a film using a static batching method. The spin coater speed was 3000 rpm and the spin coating time was controlled at 45 s. The sample was dried at 150 °C for 20 mins to a thickness of 30 nm.

[0084] (3) Preparation of perovskite layer: 328.46 mg of PbI2, 289.01 mg of PbBr2, 206.40 mg of FAI, and 77.9 mg of CsI were weighed and added to a mixed solution of 0.75 mL of DMF and 0.25 mL of DMSO to form a precursor solution. 12 mg of C4H 10 O4S was added to the precursor solution and stirred overnight. After filtration, it was spin-coated onto the electron transport layer at 4000 rpm for 60 seconds. After the 25th second, 0.5 mL of chlorobenzene was added dropwise to the top of the solution. After spin coating, the substrate was annealed on a 100°C drying oven for 15 minutes. The resulting film thickness was 350 nm. Figure 6 These are scanning electron microscope images before and after doping with small molecules. It can be seen that the grains of the perovskite film are significantly enlarged after doping.

[0085] (4) Preparation of electron transport layer: Place the spin-coated and dried substrate into a vacuum chamber and evaporate C 60 , the evaporation rate of the material film is 0.1 nm / s and the film thickness is 20 nm;

[0086] (5) Preparation of the top electrode: Place the spin-coated and dried substrate into a vacuum chamber and evaporate metallic silver. The evaporation rate of the material film is 0.1 nm / s and the film thickness is 120 nm.

[0087] Figure 7 The voltage-current density curves of devices prepared with modified and unmodified perovskite layers are compared. It can be seen from the figure that the device performance of the device prepared with the treated perovskite layer has been greatly improved: the fill factor has increased from 62% to 65%, and the energy conversion efficiency has increased from 14.65% to 15.55%.

[0088] Example 4

[0089] See also Figure 1 The perovskite solar device according to the first embodiment of the present invention has the following structure:

[0090] Glass (plastic) substrate / ITO (100 nm) / NiOx (30 nm) / FA 0.8 Cs 0.2 Pb(I0.65 Br 0.35 )3(350 nm) / C 60 (20 nm) / Ag(120 nm).

[0091] (1) Cleaning of the glass substrate pre-engraved with ITO: The transparent conductive substrate 1 (ITO glass) was cleaned using ethanol, acetone ultrasonication, and deionized water ultrasonication. After cleaning, it was placed under an infrared lamp for drying. The ITO film on the transparent conductive substrate 1 served as the anode layer 2 of the device. The square resistance of the ITO film was 15Ω to 30Ω, and the film thickness was 80 to 120nm.

[0092] (2) Preparation of hole transport layer: The dried substrate was treated with UV-ozone for 5-10 minutes, then placed on a spin coater and the prepared NiOx aqueous solution was spin-coated into a film using a static batching method. The spin coater speed was 3000 rpm and the spin coating time was controlled at 45 s. The sample was dried at 150 °C for 20 mins to a thickness of 30 nm.

[0093] (3) Preparation of perovskite layer: 328.46 mg of PbI2, 289.01 mg of PbBr2, 206.40 mg of FAI, and 77.9 mg of CsI were weighed and added to a mixed solution of 0.75 mL of DMF and 0.25 mL of DMSO to form a precursor solution. 15 mg of C4H 10 O4S was added to the precursor solution and stirred overnight. After filtration, it was spin-coated onto the electron transport layer at 4000 rpm for 60 seconds. After the 25th second, 0.5 mL of chlorobenzene was added dropwise to the top of the solution. After spin coating, the substrate was annealed on a 100°C drying oven for 15 minutes. The resulting film thickness was 350 nm. Figure 8 These are scanning electron microscope images before and after doping with small molecules. It can be seen that the grains of the perovskite film are significantly enlarged after doping.

[0094] (4) Preparation of electron transport layer: Place the spin-coated and dried substrate into a vacuum chamber and evaporate C 60 , the evaporation rate of the material film is 0.1 nm / s and the film thickness is 20 nm;

[0095] (5) Preparation of anode: Place the spin-coated and dried substrate into a vacuum chamber and evaporate metallic silver. The evaporation rate of the material film is 0.1 nm / s and the film thickness is 120 nm.

[0096] Figure 9The voltage-current density curves of devices prepared with modified and unmodified perovskite layers are compared. It can be seen from the figure that the device performance of the device prepared with the treated perovskite layer has been greatly improved: the fill factor has increased from 60% to 65%, and the energy conversion efficiency has increased from 14.57% to 15.58%.

[0097] In summary, the perovskite film, its preparation method and application of the present invention, while improving the crystallization quality of the perovskite film, passivates the vacancy defects of the perovskite film. The preparation method can be adapted to various preparation methods, including but not limited to large-area preparation methods such as spin coating, scraping, and spraying, and does not introduce additional preparation processes, thereby ensuring the repeatability and low cost of high-quality preparation.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a perovskite thin film, characterized in that: The diethyl sulfate small molecule is dissolved in the perovskite precursor solution. The concentration of the diethyl sulfate small molecule in the perovskite precursor solution is 3~15 mg / mL. The perovskite precursor solution containing the small molecule is then coated on a substrate. After annealing, a perovskite film is obtained.

2. The method for preparing a perovskite thin film according to claim 1, wherein: The small molecule is diethyl sulfate, and its molecular structure is C4H 10 O4S.

3. The method for preparing a perovskite thin film according to claim 1, wherein: The annealing temperature is 50~150℃, and the annealing time is 5~20 min.

4. The method for preparing a perovskite thin film according to claim 1, wherein: The perovskite materials used in the perovskite precursor solution include formamidine hydroiodide, cesium iodide, lead iodide and lead bromide.

5. The method for preparing a perovskite thin film according to claim 1, wherein: The perovskite precursor solution containing small molecules is coated on the substrate by spin coating, spray coating, immersion coating and blade coating.

6. A perovskite film, characterized in that Prepared according to the method according to any one of claims 1 to 5.

7. A solar cell device, characterized in that: The invention comprises a substrate (1), a transparent electrode (2), an electron transport layer (3), a perovskite film layer (4), a hole transport layer (5) and a top electrode (6) stacked in sequence from bottom to top; the perovskite film (4) is prepared according to the method according to any one of claims 1 to 5, and the thickness of the perovskite film layer (4) is 300-600 nm.

8. The solar cell device according to claim 7, characterized in that The transparent electrode (2) is made of an inorganic material or an organic conductive polymer. The inorganic material is indium tin oxide, zinc oxide or a metal oxide selected from tin oxide or a metal selected from gold, copper, silver or zinc; and the organic conductive polymer is polythiophene.

9. The solar cell device according to claim 7, characterized in that The electron transport layer (3) is made of tin oxide, titanium oxide, zinc oxide, fullerene or a fullerene derivative.

10. The solar cell device according to claim 7, characterized in that The hole transport layer (5) is made of nickel oxide, 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene, poly-3-hexylthiophene or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine].

Images