Perovskite thin film, preparation method thereof and solar cell

Abstract

The invention provides a perovskite thin film, a preparation method thereof and a solar cell. The preparation method comprises the following steps: feeding a substrate into evaporation equipment, carrying out first vacuum evaporation on a lead-containing compound and an optional dopant, then carrying out second vacuum evaporation on a first organic halide, and forming an intermediate phase film on the surface of the substrate; and carrying out solution treatment on the intermediate-phase thin film by using a passivation solution, and finally carrying out annealing treatment to obtain the perovskite thin film, the passivation solution comprises one or more of second organic halide, cesium acetate and cesium formate. According to the method, under the condition that the original vacuum evaporation raw materials are few, the evaporated perovskite intermediate phase thin film is treated through the solution method, various additives can be flexibly introduced, the content of the additives can be accurately controlled, the crystallization quality of the thin film in the annealing process is improved, and the quality and preparation repeatability of the perovskite thin film can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaics, and in particular, to a perovskite thin film, a preparation method thereof, and a solar cell. Background Art

[0002] Metal halide perovskites have advantages such as simple preparation, low cost, long carrier diffusion distance, and adjustable bandgap, and have become the most promising materials in the new generation of photovoltaic technologies. The preparation methods of perovskite thin films include solution methods and vacuum evaporation methods. At present, solution methods generally require the use of DMF as a solvent, and this solvent is highly harmful to both the environment and the human body.

[0003] Preparing perovskite by vacuum evaporation can avoid the use of solvents, but the evaporation rate needs to be precisely controlled. As the amount of evaporation raw materials increases, the requirements for equipment become higher. This is because after the amount of raw materials increases, due to the large difference in the saturated vapor pressures of different raw materials, it is difficult to control the evaporation rates of multiple materials to be stable, and it is impossible to precisely control the ratio of different additives. Therefore, there are still problems of poor experimental repeatability and obvious batch differences in preparing perovskite thin films by vacuum evaporation. In addition, due to the limited selection of evaporation materials, the choice of additives for modifying the thin film is limited during the evaporation process. Summary of the Invention

[0004] The main object of the present invention is to provide a perovskite thin film, a preparation method thereof, and a solar cell to solve the problems of poor repeatability and difficulty in modification when preparing perovskite thin films by vacuum evaporation in the prior art.

[0005] To achieve the above object, according to one aspect of the present invention, a preparation method of a perovskite thin film is provided, including the following steps: Step S1, feeding a substrate into an evaporation device, and performing a first vacuum evaporation on a lead-containing compound and an optional dopant to form a first thin film on the surface of the substrate; Step S2, performing a second vacuum evaporation on a first organic halide to form a second thin film on the surface of the first thin film, the second thin film reacts with the first thin film, and an intermediate-phase thin film is formed on the surface of the substrate; Step S3, performing a solution treatment on the intermediate-phase thin film with a passivation solution to obtain a passivated thin film; Step S4, annealing the passivated thin film to obtain a perovskite thin film; wherein, the passivation solution includes a solvent and a passivation additive, and the passivation additive includes one or more of a second organic halide, cesium acetate, and cesium formate.

[0006] Further, the lead-containing compound includes one or more of lead iodide, lead bromide, lead chloride, lead acetate, and lead thiocyanate; and / or, the dopant includes cesium bromide and / or cesium iodide; and / or, the first organic halide includes one or more of methylammonium hydroiodide, methylammonium hydrobromide, methylammonium hydrochloride, formamidinium hydroiodide, formamidinium hydrobromide, and formamidinium hydrochloride.

[0007] Further, the weight ratio of the lead-containing compound to the first organic halide is 1000:(1000 - 1200); and / or, the weight ratio of the lead-containing compound to the dopant is 1000:(0 - 80).

[0008] Further, the temperature of the first vacuum evaporation is 350 - 500 °C, the vacuum degree is 10 -3 -10 -4 Pa, and the material evaporation rate is The thickness of the first thin film is 200 - 400 nm; and / or, the temperature of the second vacuum evaporation is 200 - 350 °C, the vacuum degree is 10 -3 -10 -4 Pa, and the material evaporation rate is The thickness ratio of the second thin film to the first thin film is (1 - 2):1.

[0009] Further, in step S1, before the first vacuum evaporation of the lead-containing compound and the optional dopant, there is also a step of pre-melting the lead-containing compound and the optional dopant. The temperature of the pre-melting treatment is 300 - 360 °C, and the time is 10 - 130 min.

[0010] Further, in step S3, the mass concentration of the passivation solution is 0.1 - 10 mg / mL; and / or, the second organic halide includes one or more of methylammonium hydroiodide, methylammonium hydrobromide, methylammonium hydrochloride, formamidinium hydroiodide, formamidinium hydrobromide, formamidinium hydrochloride, cesium iodide, cesium bromide, cesium chloride, phenethylamine iodide, phenethylamine bromide, phenethylamine chloride, o-fluorophenethylamine iodide, m-fluorophenethylamine iodide, p-fluorophenethylamine iodide, o-fluorophenethylamine bromide, m-fluorophenethylamine bromide, p-fluorophenethylamine bromide, o-fluorophenethylamine chloride, m-fluorophenethylamine chloride, p-fluorophenethylamine chloride; and / or, the solvent includes one or more of isopropyl alcohol, chlorobenzene, ethyl acetate, and ether; and / or, the solution treatment includes one or more of spin coating, dipping, blade coating, and spraying.

[0011] Further, the lead-containing compound is PbI 2 , the dopant is CsI, the first organic halide is formamidinium hydroiodide, and the passivation solution is an isopropyl alcohol solution of cesium acetate; or, the lead-containing compound is PbI 2 , the dopant is CsBr, the first organic halide is methylammonium hydroiodide, and the passivation solution is an isopropyl alcohol solution of cesium acetate; or, the lead-containing compound is PbI 2 , the dopant is CsI, the first organic halide is formamidinium hydroiodide, and the passivation solution is an isopropyl alcohol solution of cesium formate.

[0012] Further, in step S4, the temperature of the annealing treatment is 70 - 200 °C, and the time is 5 - 60 min.

[0013] According to another aspect of the present invention, a perovskite thin film is provided, which is obtained by using the preparation method described above in the present invention.

[0014] According to another aspect of the present invention, a solar cell is provided, which includes the perovskite thin film described above in the present invention.

[0015] Applying the technical solution of the present invention, first, the perovskite raw material is subjected to vacuum evaporation in sequence to form an intermediate phase thin film on the substrate; then, a passivation solution is used to passivate the defects of the intermediate phase thin film, fill the cation or halogen ion vacancy defects, and passivate the lead with low coordination to improve the crystallization quality of the perovskite, so as to obtain a passivated thin film; finally, the passivated thin film is annealed to convert the perovskite intermediate phase thin film into a perovskite phase, and a perovskite thin film is obtained. While maintaining less original vacuum evaporation raw materials, the present invention can flexibly introduce various additives and precisely control the content of the additives by treating the evaporated perovskite intermediate phase thin film by the solution method, improve the crystallization quality of the thin film during the annealing process, and is beneficial to improving the quality and preparation repeatability of the perovskite thin film. Specific Embodiments

[0016] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0017] As described in the background art of the present invention, in the prior art, there are problems of poor repeatability and difficulty in modification when preparing perovskite thin films by vacuum evaporation. In particular, due to the large difference in saturated vapor pressure of different raw materials, it is difficult to precisely control the proportion of additives, resulting in poor repeatability of the thin film, and the selection of evaporation materials is limited, which restricts the selection range of thin film modification additives. To solve the above problems, in a typical embodiment of the present invention, a preparation method of a perovskite thin film is provided, including the following steps: Step S1, feeding a substrate into an evaporation device, and performing a first vacuum evaporation on a lead-containing compound and an optional dopant to form a first thin film on the surface of the substrate; Step S2, performing a second vacuum evaporation on a first organic halide to form a second thin film on the surface of the first thin film, the second thin film reacts with the first thin film, and an intermediate phase thin film is formed on the surface of the substrate; Step S3, performing a solution treatment on the intermediate phase thin film with a passivation solution to obtain a passivated thin film; Step S4, annealing the passivated thin film to obtain a perovskite thin film; wherein, the passivation solution includes a solvent and a passivation additive, and the passivation additive includes one or more of a second organic halide, cesium acetate, and cesium formate.

[0018] Specifically, first, the substrate is fed into the evaporation coating equipment, and the lead-containing compound and an optional dopant are subjected to the first vacuum evaporation coating to form a first thin film on the surface of the substrate as the inorganic framework of the intermediate phase thin film; then the first organic halide is subjected to the second vacuum evaporation coating to form a second thin film on the surface of the first thin film. The organic halide in the second thin film reacts with the lead-containing compound in the first thin film to form a perovskite intermediate phase, so as to form an intermediate phase thin film on the substrate. It should be noted that due to the reaction between the second thin film and the first thin film during the evaporation coating process, the thickness of the formed intermediate phase thin film is not a simple stack of the thicknesses of the two thin films.

[0019] Then, the intermediate phase thin film is subjected to solution treatment using a passivation solution, and a passivation additive is used to passivate the defects of the intermediate phase thin film, fill the cation or halogen ion vacancy defects, and passivate the lead with low coordination to improve the crystallization quality of the perovskite and obtain a passivated thin film. Finally, the passivated thin film is annealed to convert the perovskite intermediate phase thin film into a perovskite phase to obtain a perovskite thin film.

[0020] By introducing different materials in stages, the proportion of each component can be more precisely controlled, the problem that it is difficult to control the proportion of additives caused by the difference in saturated vapor pressure can be further improved, the possibility of introducing multiple modifiers is provided, and at the same time, the selection range of evaporation coating materials can be expanded, which is beneficial to passivating film defects and adjusting film structure, thereby significantly improving the quality and optoelectronic performance of the film.

[0021] In the case of maintaining less original vacuum evaporation coating raw materials, the present invention can flexibly introduce a variety of additives and precisely control the content of the additives by treating the perovskite intermediate phase thin film after evaporation coating by the solution method, improve the crystallization quality of the thin film during the annealing process, which is beneficial to improving the quality and preparation repeatability of the perovskite thin film, and further improving the optoelectronic performance of the solar cell using the perovskite thin film.

[0022] In a preferred embodiment, the lead-containing compound includes one or more of lead iodide, lead bromide, lead chloride, lead acetate, and lead thiocyanate; and / or, the dopant includes cesium bromide and / or cesium iodide; and / or, the first organic halide includes one or more of methylammonium hydroiodide, methylammonium hydrobromide, methylammonium hydrochloride, formamidinium hydroiodide, formamidinium hydrobromide, and formamidinium hydrochloride. The selection of the above lead-containing compound and the use of the dopant can more precisely regulate the chemical composition of the thin film, thereby further improving the carrier mobility, improving the light absorption characteristics, and optimizing its optoelectronic performance. The above first organic halide is more conducive to being used as a building unit of the perovskite thin film, improving the stability and consistency of the thin film.

[0023] The appropriate use of dopants can further modify the thin film and enhance its optoelectronic properties without significantly increasing complexity. In a preferred embodiment, the weight ratio of the lead-containing compound to the first organic halide is 1000:(1000 - 1200); and / or, the weight ratio of the lead-containing compound to the dopant is 1000:(0 - 80), preferably 1000:(30 - 70). When the ratio of the lead-containing compound to the organic halide is within the above range, it is not only conducive to the stable construction of the perovskite framework, but also more conducive to introducing ions to fill the inorganic framework to regulate the structure and improve performance.

[0024] By controlling the evaporation rate and evaporation thickness of the raw materials, the reaction degree can be further controlled, thereby controlling the quality of the formed intermediate-phase thin film. In a preferred embodiment, the temperature of the first vacuum evaporation is 350 - 500 °C, the vacuum degree is 10 -3 ~10 -4 Pa, and the evaporation rate of the material is preferably The thickness of the first thin film is 200 - 400 nm; and / or, the temperature of the second vacuum evaporation is 200 - 350 °C, the vacuum degree is 10 -3 ~10 -4 Pa, and the evaporation rate of the material is preferably The thickness ratio of the second thin film to the first thin film is (1 - 2):1.

[0025] The high temperature and high evaporation rate of the first vacuum evaporation are conducive to the rapid formation of a uniform inorganic framework of the lead-containing compound, while the low temperature and slow evaporation rate of the second vacuum evaporation are conducive to more meticulous filling and controlling the structure of the intermediate-phase thin film. The above vacuum evaporation parameters are more conducive to the stable evaporation of raw materials and reduce the disproportion caused by different saturated vapor pressures. The precise control of the material evaporation rate, especially the preferred rate range, is conducive to the formation of a uniform thin film and improves the thin film quality.

[0026] It should be noted that as described above, the thickness of the formed intermediate-phase thin film is not a simple lamination of the thicknesses of the two thin films, so its thickness is difficult to quantify. By controlling the evaporation film thickness ratio of the second thin film to the first thin film, the reaction degree between the two can be controlled to obtain the final intermediate-phase thin film.

[0027] Preferably, the temperature of the first vacuum evaporation is higher than that of the second vacuum evaporation. The evaporation rate of the material in the first vacuum evaporation is higher than that in the second vacuum evaporation, and the difference is By setting the thin film thickness within the above range and combining with the control of evaporation parameters, the uniformity and integrity of the thin film can be improved. The preferred evaporation rate difference can also improve the good interfacial bonding between layers, further enhance the stability and consistency of the thin film, and is conducive to improving the repeatability of preparation.

[0028] In a preferred embodiment, in step S1, before the first vacuum evaporation of the lead-containing compound and the optional dopant, a pre-melting treatment step of the lead-containing compound and the optional dopant is further included. The temperature of the pre-melting treatment is 300-360 °C, and the time is 10-130 min. The pre-melting treatment can further improve the compatibility and reactivity of the raw materials, control the evaporation uniformity of the materials, avoid explosive evaporation, make the film nucleation and growth process more stable, and is beneficial to improving the film performance.

[0029] For the purpose of more conducive to realizing the precise modification of the film, promoting the formation of a higher-quality perovskite phase, passivating defects at the same time, and improving the performance stability and preparation repeatability of the perovskite film, in a preferred embodiment, in step S3, the mass concentration of the passivation solution is 0.1-10 mg / mL; and / or, the weight ratio of the lead-containing compound to the passivation additive is 1000:(0.08-0.15); and / or, the second organic halide includes one or more of methylammonium hydroiodide, methylammonium hydrobromide, methylammonium hydrochloride, formamidinium hydroiodide, formamidinium hydrobromide, formamidinium hydrochloride, cesium iodide, cesium bromide, cesium chloride, phenethylamine iodide, phenethylamine bromide, phenethylamine chloride, o-fluorophenethylamine iodide, m-fluorophenethylamine iodide, p-fluorophenethylamine iodide, o-fluorophenethylamine bromide, m-fluorophenethylamine bromide, p-fluorophenethylamine bromide, o-fluorophenethylamine chloride, m-fluorophenethylamine chloride, p-fluorophenethylamine chloride; and / or, the solvent includes one or more of isopropanol, chlorobenzene, ethyl acetate and ether; and / or, the solution treatment includes one or more of spin coating, dipping, blade coating and spraying, and only needs to cover the surface of the intermediate phase film.

[0030] The type of the passivation additive can be selected according to the needs of the film. The above-mentioned amount of the passivation additive can more fully repair the defects of the intermediate phase film, can further improve the film quality, enhance the preparation repeatability, and provide more powerful technical support for the high-performance and large-scale preparation of the perovskite film.

[0031] It should be noted that after the solution treatment, the passivation solution is uniformly distributed on the surface of the intermediate phase film and enters the film interior, and the passivating agent molecules fill the cation or halogen vacancy defects in the intermediate phase film. Generally, only the concentration of the passivation solution is limited, and the volume can be adjusted according to the size of the film. When the size of the intermediate phase film is the same, by controlling the mass fraction of the passivation solution and changing the concentration to adjust the amount of the passivating agent, different passivation effects can be achieved. These are understandable to those skilled in the art and will not be elaborated here.

[0032] Preferably, the solution is processed by spin coating at a rotational speed of 2500 - 3500 rpm for 20 - 60 s. Under the above conditions, the uniform distribution of the passivator can be promoted, further passivating the defects on the surface and inside of the thin film and improving the optoelectronic properties of the thin film. Compared with the single vacuum evaporation method, solution processing methods such as spin coating can more flexibly control the types and contents of additives, are not limited by the saturated vapor pressure of materials, and improve the freedom and accuracy of thin film modification.

[0033] In a preferred embodiment, the lead-containing compound is PbI 2 , the dopant is CsI, the first organic halide is formamidinium hydroiodide, and the passivation solution is an isopropanol solution of cesium acetate; or, the lead-containing compound is PbI 2 , the dopant is CsBr, the first organic halide is methylammonium hydroiodide, and the passivation solution is an isopropanol solution of cesium acetate; or, the lead-containing compound is PbI 2 , the dopant is CsI, the first organic halide is formamidinium hydroiodide, and the passivation solution is an isopropanol solution of cesium formate. The above organic halogen compounds can more fully fill the inorganic framework formed by the corresponding lead-containing compound to form a more stable perovskite intermediate phase thin film; the above passivation solution can better passivate the defects of the corresponding intermediate phase thin film, improve the crystallization quality of the thin film during annealing, and obtain a perovskite thin film with better optoelectronic properties and preparation repeatability.

[0034] The annealing temperature and time can be flexibly adjusted according to the phase transition temperatures of different perovskites. In a preferred embodiment, in step S4, the annealing temperature is 70 - 200 °C and the time is 5 - 60 min. Preferably, the annealing temperature is 150 - 200 °C and the time is 10 - 30 min. Within the above ranges, the efficient transformation of the perovskite phase can be promoted, further improving the crystallinity and uniformity of the thin film, thereby significantly improving the repeatability and performance stability of the thin film. Especially within the preferred range, the phase transition speed and defect repair can be more effectively balanced, reducing the performance degradation of the thin film caused by high-temperature long-time annealing, while promoting the effective integration of additives and improving the carrier transport characteristics of the thin film.

[0035] In yet another typical embodiment of the present invention, a perovskite thin film obtained by using the above preparation method of the present invention is also provided. Due to the use of the preparation method of the present invention, it has significantly improved thin film properties, good preparation repeatability, and further can improve the optoelectronic properties of the solar cells using it.

[0036] In another typical embodiment of the present invention, a solar cell is also provided, which includes the perovskite thin film of the present invention as described above, and may also include other conventional components, such as a hole transport layer, an electron transport layer, electrodes, a conductive substrate, etc. The preparation method can be carried out by conventional methods, for example, it may include the following steps: Step 1, ultrasonically clean and ozone-treat the conductive substrate to obtain a treated conductive substrate; Step 2, deposit a hole transport layer on the treated conductive substrate; Step 3, prepare a perovskite thin film on the hole transport layer; Step 4, deposit an electron transport layer on the perovskite thin film; Step 5, deposit electrode materials on the electron transport layer to obtain a solar cell.

[0037] Typically but not limitedly, the weight ratio of the lead-containing compound to the first organic halide is 1000:1000, 1000:1050, 1000:1100, 1000:1150, 1000:1200, or a range value composed of any two of these numerical values.

[0038] Typically but not limitedly, the weight ratio of the lead-containing compound to the dopant is 1000:0, 1000:10, 1000:20, 1000:30, 1000:40, 1000:50, 1000:60, 1000:70, 1000:80, or a range value composed of any two of these numerical values.

[0039] Typically but not limitedly, the mass concentration of the passivation solution is 0.1 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL, 10 mg / mL, or a range value composed of any two of these numerical values.

[0040] Typically but not limitedly, the temperature of the first vacuum evaporation is 350 °C, 380 °C, 400 °C, 420 °C, 450 °C, 480 °C, 500 °C, or a range value composed of any two of these numerical values, and the material evaporation rate is or a range value composed of any two of these numerical values.

[0041] Typically but not limitedly, the temperature of the second vacuum evaporation is 200 °C, 220 °C, 250 °C, 280 °C, 300 °C, 320 °C, 350 °C, or a range value composed of any two of these numerical values, and the material evaporation rate is or a range value composed of any two of these numerical values.

[0042] Typically but not limited to, the temperature for the annealing treatment is 70°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, or a range value composed of any two of these values, and the time is 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, or a range value composed of any two of these values.

[0043] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0044] Example 1

[0045] Preparation method of perovskite thin film:

[0046] Step S1, Feed the substrate into the evaporation coating equipment, and perform pre-melting treatment (temperature is 350°C, time is 10 min) on the lead-containing compound (1000 mg PbI 2 ), and the dopant (60 mg CsI) in the evaporation crucible. Subsequently, perform the first vacuum evaporation (temperature is 400°C, vacuum degree is 3×10 -4 Pa, and the material evaporation rate is ) to form a first thin film (thickness is 270 nm) on the surface of the substrate;

[0047] Step S2, Place the first organic halide (1000 mg formamidinium hydroiodide) in the evaporation boat, and perform the second vacuum evaporation (evaporation power is at a temperature of 200°C, vacuum degree is 4×10 -3 Pa, and the material evaporation rate is ) to form a second thin film (thickness is 500 nm) on the surface of the first thin film. The second thin film reacts with the first thin film to form an intermediate phase thin film;

[0048] Step S3, Use a passivation solution (50 μL of an isopropanol solution of cesium acetate with a mass concentration of 2 mg / mL) to perform solution treatment (spin coating, rotation speed is 3000 rpm, time is 30 s) on the intermediate phase thin film to obtain a passivated thin film;

[0049] Step S4, Anneal the passivated thin film (temperature is 170°C, time is 20 min) to obtain a perovskite thin film.

[0050] Preparation method of solar cell:

[0051] Step 1, Provide a transparent conductive substrate: Ultrasonically clean the ITO conductive glass with dishwashing liquid, water, and ethanol for 15 min respectively, dry it for use, and then ozone-treat the cleaned ITO conductive glass for 15 min and set it aside;

[0052] Step 2, preparing the hole transport layer: Spin-coat 0.1 mL of a NiO aqueous dispersion with a mass concentration of 15 mg / mL at a speed of 3000 rpm on the conductive surface of the ITO conductive glass for 30 s. Then, anneal it on a hot plate at 120 °C for 20 min to obtain a NiO layer with a thickness of 10 nm. x (where x is 1 - 2) on the conductive surface of the ITO conductive glass for 30 s. Then, anneal it on a hot plate at 120 °C for 20 min to obtain a NiO layer with a thickness of 10 nm. x layer;

[0053] Step 3, put the above materials into the evaporation equipment and prepare the perovskite thin film according to the above method to form the perovskite layer;

[0054] Step 4, preparing the electron transport layer: On the surface of the perovskite layer away from the ITO conductive glass, deposit at a deposition rate to obtain a C layer with a thickness of 30 nm; 60 layer;

[0055] Step 5, preparing the metal electrode layer: On the surface of the C layer away from the ITO conductive glass, deposit at 60 a deposition rate to obtain a Cu electrode layer with a thickness of 100 nm, thus obtaining the solar cell. a deposition rate to obtain a Cu electrode layer with a thickness of 100 nm, thus obtaining the solar cell.

[0056] Example 2

[0057] The difference from Example 1 lies in the preparation method of the perovskite thin film:

[0058] Step S1, put the substrate into the evaporation equipment, pre-melt the lead-containing compound (1000 mg PbI 2 ) and the dopant (30 mg CsBr) in the evaporation crucible (temperature is 350 °C, time is 60 min). Then, perform the first vacuum evaporation (temperature is 400 °C, vacuum degree is 3×10 -4 Pa, the material evaporation rate is ) to form a first thin film (thickness is 270 nm) on the surface of the substrate;

[0059] Step S2, place the first organic halide (1000 mg formamidinium hydroiodide) in the evaporation boat and perform the second vacuum evaporation (evaporation power is, temperature is 250 °C, vacuum degree is 4×10 -3 Pa, the material evaporation rate is ) to form a second thin film (thickness is 500 nm) on the surface of the first thin film. The second thin film reacts with the first thin film to form an intermediate-phase thin film.

[0060] Example 3

[0061] The difference from Example 1 lies in the preparation method of the perovskite thin film:

[0062] Step S1: Feed the substrate into the evaporation coating equipment. Pre-melt the lead-containing compound (1000 mg PbI 2 ) and the dopant (70 mg CsBr) in the evaporation crucible (temperature: 350 °C, time: 60 min). Then, perform the first vacuum evaporation (temperature: 430 °C, vacuum degree: 3×10 -4 Pa, material evaporation rate: ) to form a first thin film (thickness: 300 nm) on the surface of the substrate;

[0063] Step S2: Place the first organic halide (1000 mg formamidinium hydroiodide) in the evaporation boat and perform the second vacuum evaporation (evaporation power, temperature: 250 °C, vacuum degree: 4×10 -3 Pa, material evaporation rate: ) to form a second thin film (thickness: 540 nm) on the surface of the first thin film. The second thin film reacts with the first thin film to form an intermediate phase thin film.

[0064] Example 4

[0065] The difference from Example 1 lies in the method for preparing the perovskite thin film:

[0066] Step S4: Anneal the passivation thin film (temperature: 150 °C, time: 30 min) to obtain the perovskite thin film.

[0067] Example 5

[0068] The difference from Example 1 lies in the method for preparing the perovskite thin film:

[0069] Step S4: Anneal the passivation thin film (temperature: 200 °C, time: 10 min) to obtain the perovskite thin film.

[0070] Example 6

[0071] The difference from Example 1 lies in the method for preparing the perovskite thin film:

[0072] Step S1: Feed the substrate into the evaporation coating equipment. Pre-melt the lead-containing compound (1000 mg PbI 2 ) in the evaporation crucible (temperature: 300 °C, time: 130 min). Then, perform the first vacuum evaporation (temperature: 350 °C, vacuum degree: 3×10 -4 Pa, material evaporation rate: ) to form a first thin film (thickness: 200 nm) on the surface of the substrate;

[0073] Step S2, place the first organic halide (1000 mg formamidinium hydroiodide) in an evaporation boat, and perform a second vacuum evaporation (the evaporation power is at a temperature of 200 °C, the vacuum degree is 4×10 -3 Pa, and the material evaporation rate is ), so as to form a second thin film (with a thickness of 200 nm) on the surface of the first thin film. The second thin film reacts with the first thin film to form an intermediate phase thin film.

[0074] Example 7

[0075] The difference from Example 1 lies in the preparation method of the perovskite thin film:

[0076] Step S1, send the substrate into the evaporation equipment, and perform pre-melting treatment (at a temperature of 360 °C for 10 min) on the lead-containing compound (1000 mg PbI 2 ) and the dopant (80 mg CsI) in the evaporation crucible. Subsequently, perform a first vacuum evaporation (at a temperature of 500 °C, the vacuum degree is 3×10 -4 Pa, and the material evaporation rate is ), so as to form a first thin film (with a thickness of 400 nm) on the surface of the substrate;

[0077] Step S2, place the first organic halide (1200 mg formamidinium hydroiodide) in an evaporation boat, and perform a second vacuum evaporation (the evaporation power is at a temperature of 350 °C, the vacuum degree is 4×10 -3 Pa, and the material evaporation rate is ), so as to form a second thin film (with a thickness of 800 nm) on the surface of the first thin film. The second thin film reacts with the first thin film to form an intermediate phase thin film.

[0078] Example 8

[0079] The difference from Example 1 lies in the preparation method of the perovskite thin film:

[0080] Step S3, use a passivation solution (50 μL of an ethyl ether solution of methylamine hydroiodide with a mass concentration of 0.1 mg / mL) to perform solution treatment (spin coating, rotation speed of 2500 rpm, time of 60 s) on the intermediate phase thin film to obtain a passivated thin film

[0081] Step S4, perform annealing treatment (at a temperature of 70 °C for 60 min) on the passivated thin film to obtain a perovskite thin film.

[0082] Example 9

[0083] The difference from Example 1 lies in the preparation method of the perovskite thin film:

[0084] Step S3, the intermediate phase film was solution-treated (spin-coated at a rotational speed of 3500 rpm for 20 s) with a passivation solution (50 μL of an ethyl acetate solution of cesium formate with a mass concentration of 10 mg / mL) to obtain a passivation film.

[0085] Step S4, the passivation film was annealed (at a temperature of 200 °C for 5 min) to obtain a perovskite film.

[0086] Example 10

[0087] The difference from Example 1 lies in the preparation method of the perovskite film:

[0088] Step S2, the first organic halide (1000 mg of methylammonium hydroiodide) was placed in an evaporation boat, and a second vacuum evaporation was carried out (the evaporation power was at a temperature of 200 °C, the vacuum degree was 4×10 -3 Pa, and the material evaporation rate was ), so as to form a second film (with a thickness of 500 nm) on the surface of the first film, and the second film reacted with the first film to form an intermediate phase film.

[0089] Comparative Example 1

[0090] The difference from Example 1 lies in that the preparation method of the perovskite film is different: the intermediate phase film was not solution-treated, and the intermediate phase film was directly annealed to obtain a perovskite film.

[0091] The photovoltaic performance of the solar cells prepared in the above examples and comparative examples was tested. The effective area of the device was 0.09 mm 2 , and the performance of the solar cells was tested using a solar simulator (Gurung Technology, SS-X) and a Keithley 2400 source meter under the simulated solar light condition of 100 mW / cm 2 . The test results are shown in Table 1.

[0092] Table 1

[0093]

[0094] As can be seen from the above, compared with the comparative examples, in each embodiment of the present invention, the perovskite raw materials are first subjected to vacuum evaporation in sequence to form an intermediate phase film on the substrate; then a passivation solution is used to passivate the defects of the intermediate phase film, fill the cation or halogen ion vacancy defects, and passivate the lead with low coordination to improve the crystallization quality of the perovskite, obtaining a passivated film; finally, the passivated film is annealed to convert the perovskite intermediate phase film into a perovskite phase, obtaining a perovskite film. While maintaining less original vacuum evaporation raw materials, the present invention can flexibly introduce various additives and precisely control the content of the additives by treating the evaporated perovskite intermediate phase film by solution method, improving the crystallization quality of the film during annealing, which is beneficial to improving the quality and preparation repeatability of the perovskite film.

[0095] In addition, it can be seen that when all process parameters are within the preferred range of the present invention, the comprehensive effect is better.

[0096] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a perovskite film, characterized in that: The following steps are involved: Step S1, sending a substrate into an evaporation device, and performing a first vacuum evaporation on a lead-containing compound and an optional dopant to form a first thin film on the surface of the substrate; Step S2, performing a second vacuum evaporation on the first organic halide to form a second thin film on the surface of the first thin film, wherein the second thin film reacts with the first thin film to form an intermediate phase thin film on the surface of the substrate; Step S3, using a passivation solution to perform solution treatment on the mesophase film to obtain a passivation film; Step S4, annealing the passivation film to obtain the perovskite film; The passivation solution comprises a solvent and a passivation additive, and the passivation additive comprises one or more of a second organic halide, cesium acetate and cesium formate.

2. The preparation method according to claim 1, characterized in that: The lead-containing compound includes one or more of lead iodide, lead bromide, lead chloride, lead acetate and lead thiocyanate; and / or, The dopant comprises cesium bromide and / or cesium iodide; and / or, The first organic halide includes one or more of methylamine hydroiodide, methylamine hydrobromide, methylamine hydrochloride, formamidine hydroiodide, formamidine hydrobromide and formamidine hydrochloride.

3. The preparation method according to claim 1 or 2, characterized in that: The weight ratio of the lead-containing compound to the first organic halide is 1000:(1000-1200); and / or, The weight ratio of the lead-containing compound to the dopant is 1000:(0-80).

4. The preparation method according to any one of claims 1 to 3, characterized in that The temperature of the first vacuum evaporation is 350-500°C, and the vacuum degree is 10 -3 ~10 -4 Pa, the material evaporation rate is The thickness of the first film is 200-400 nm; and / or, The temperature of the second vacuum evaporation is 200-350°C, and the vacuum degree is 10 -3 ~10 -4 Pa, the material evaporation rate is The thickness ratio of the second film to the first film is (1-2):

1.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In the step S1, before subjecting the lead-containing compound and the optional dopant to the first vacuum evaporation, the step also includes subjecting the lead-containing compound and the optional dopant to a pre-melting treatment, wherein the pre-melting treatment is performed at a temperature of 300 to 360° C. and for a time of 10 to 130 minutes.

6. The preparation method according to any one of claims 1 to 5, characterized in that In the step S3, The mass concentration of the passivation solution is 0.1 to 10 mg / mL; and / or, The second organic halide comprises one or more of methylamine hydroiodide, methylamine hydrobromide, methylamine hydrochloride, formamidine hydroiodide, formamidine hydrobromide, formamidine hydrochloride, cesium iodide, cesium bromide, cesium chloride, phenethylamine iodine, phenethylamine bromide, phenethylamine chloride, o-fluorophenethylamine iodine, m-fluorophenethylamine iodine, p-fluorophenethylamine iodine, o-fluorophenethylamine bromide, m-fluorophenethylamine bromide, p-fluorophenethylamine bromide, o-fluorophenethylamine chloride, m-fluorophenethylamine chloride, and p-fluorophenethylamine chloride; and / or, The solvent comprises one or more of isopropanol, chlorobenzene, ethyl acetate and diethyl ether; and / or, The solution processing includes one or more of spin coating, dipping, doctor blade coating and spraying.

7. The preparation method according to any one of claims 1 to 6, characterized in that The lead-containing compound is PbI2, the dopant is CsI, the first organic halide is formamidine hydroiodide, and the passivation solution is an isopropanol solution of cesium acetate; or The lead-containing compound is PbI2, the dopant is CsBr, the first organic halide is methylamine hydroiodide, and the passivation solution is an isopropanol solution of cesium acetate; or The lead-containing compound is PbI2, the dopant is CsI, the first organic halide is formamidine hydroiodide, and the passivation solution is an isopropanol solution of cesium formate.

8. The preparation method according to any one of claims 1 to 7, characterized in that In the step S4, the annealing treatment is performed at a temperature of 70 to 200° C. and for a time of 5 to 60 minutes.

9. A perovskite film, characterized in that: The method according to any one of claims 1 to 8 is used.

10. A solar cell, characterized in that: Comprising the perovskite film as described in claim 9.

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