Perovskite thin film and method for preparing the same, perovskite solar cell and photovoltaic module

Abstract

The application relates to the technical field of batteries, in particular to a perovskite thin film and a preparation method thereof, a perovskite solar cell and a photovoltaic module. The preparation method of the perovskite thin film comprises the following steps: providing a substrate; preparing a halide inorganic phase layer through thermal evaporation on the substrate; transferring the halide inorganic phase layer formed on the substrate to an ultraviolet ozone treatment cavity, and performing ultraviolet ozone treatment on the halide inorganic phase layer; depositing an organic salt on the halide inorganic phase layer after the ultraviolet ozone treatment; and performing annealing treatment on the substrate with the deposited organic salt, so as to form a perovskite thin film. Through the ultraviolet ozone treatment on the inorganic phase layer, the application promotes the penetration and diffusion of the organic phase solution to the inorganic phase layer, ensures the full reaction of the two phases, reduces the content of unreacted metal halide at the buried interface of the perovskite thin film, and improves the photoelectric performance and stability of the battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to perovskite thin films and their preparation methods, perovskite solar cells and photovoltaic modules. Background Technology

[0002] The fabrication processes of perovskite thin films mainly include one-step and two-step methods. Among them, the two-step method combining thermal evaporation and solution processing is considered one of the main industrial routes for the large-area, uniform fabrication of perovskite thin films. This method first prepares a metal halide inorganic phase layer through thermal evaporation, and then prepares an organic salt layer on the inorganic phase layer through solution processing, allowing the inorganic phase layer and the organic salt layer to react and form the perovskite thin film. However, this process generally suffers from a large amount of unreacted metal halides (such as lead iodide) remaining at the buried interface of the perovskite thin film. These unreacted metal halides can become non-radiative recombination centers, severely affecting carrier separation and transport, reducing the open-circuit voltage and fill factor of the cell, and ultimately leading to a decline in the photoelectric performance and stability of the device. Summary of the Invention

[0003] Based on this, the main objective of this application is to provide a method for preparing perovskite thin films. By subjecting the inorganic phase layer to ultraviolet ozone treatment, the method promotes the penetration and diffusion of the organic phase solution into the inorganic phase layer, ensuring sufficient reaction between the two phases, reducing the content of unreacted metal halides at the buried interface of the perovskite thin film, and improving the photoelectric performance and stability of the battery.

[0004] The first aspect of this application provides a method for preparing a perovskite thin film, comprising the following steps:

[0005] Provide a base;

[0006] Halide inorganic phase layers were prepared by thermal evaporation on a substrate;

[0007] The halide inorganic phase layer formed on the substrate is transferred to the ultraviolet ozone treatment chamber for ultraviolet ozone treatment.

[0008] Organic salts are deposited on a halide inorganic phase layer after ultraviolet ozone treatment, and the substrate with deposited organic salts is annealed to form a perovskite film.

[0009] In some embodiments, the halide inorganic phase layer includes lead iodide. In some embodiments, the halide inorganic phase layer also includes at least one selected from lead chloride, lead bromide, cesium chloride, cesium bromide, and cesium iodide.

[0010] In some embodiments, the thickness of the halide inorganic phase layer is 200 nm to 700 nm.

[0011] In some implementations, ultraviolet ozone treatment satisfies at least one of the following conditions:

[0012] (1) The ultraviolet light wavelength is 185 nm and / or 254 nm;

[0013] (2) The power density of ultraviolet light is 10 mW / cm². 2 ~120mW / cm 2 .

[0014] In some implementations, the oxygen flow rate in the ultraviolet ozone treatment is 0.1 L / min to 3 L / min.

[0015] In some implementations, the temperature in the ultraviolet ozone treatment is 50°C to 100°C.

[0016] The second aspect of this application provides a perovskite thin film, which is prepared using the perovskite thin film preparation method provided in the first aspect of this application.

[0017] A third aspect of this application provides a perovskite solar cell, including the perovskite thin film provided in the second aspect of this application.

[0018] A fourth aspect of this application provides a photovoltaic module, including the perovskite solar cell provided in the third aspect of this application.

[0019] Compared with traditional technologies, this application has the following advantages:

[0020] This application addresses the problem of poor permeability of organic salt solutions on the surface of dense inorganic phase layers by subjecting the inorganic phase layer to ultraviolet ozone (UVO) treatment after preparation and before organic salt deposition. This prevents premature formation of perovskite on the upper surface from blocking subsequent permeation reactions. It effectively reduces or eliminates unreacted metal halides at the buried interface of the perovskite film, mitigating their negative impact on device performance as non-radiative recombination centers. It significantly improves the physical permeation rate of the organic phase solution and the intrinsic reaction rate of perovskite nucleation and growth. This fundamentally solves the technical problems of incomplete reaction and residual metal halide at the bottom interface in the two-step method combining thermal evaporation and solution deposition, achieving high film quality and low-cost preparation for large-area perovskite film fabrication. Attached Figure Description

[0021] To better describe and illustrate embodiments or examples of the applications disclosed herein, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the embodiments or examples currently described, or the best mode of conduct of these applications as currently understood. Furthermore, throughout the drawings, the same reference numerals denote the same parts.

[0022] Figure 1 This is a schematic diagram of a method for preparing a perovskite thin film according to one embodiment of this application.

[0023] Figure 2 This is a schematic diagram of the structure of a perovskite solar cell in one embodiment of this application.

[0024] Figure 3 This is a schematic diagram of the structure of a perovskite solar cell in another embodiment of this application. Detailed Implementation

[0025] A detailed reference is now provided to embodiments of this application, one or more of which are described below. Each embodiment is provided for explanation and not for limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0026] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed in this document; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, stating that a parameter is an integer ≥ 2 is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, stating that a parameter is an integer selected from "2-10" is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0027] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0028] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0029] Unless otherwise specified, the terms "comprising," "containing," and "including" as used in this application can be open-ended or closed-ended. In open-ended cases, for example, "comprising," "containing," and "including" can mean that other members, elements, or method steps not listed can also be included, or that only the listed members, elements, or method steps can be included.

[0030] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0031] In this application, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0032] like Figure 1 As shown, the first aspect of this application provides a method for preparing a perovskite thin film, comprising the following steps:

[0033] S1, Provide the base.

[0034] S2. Prepare a halide inorganic phase layer by thermal evaporation on the substrate.

[0035] S3. The halide inorganic phase layer formed on the substrate is transferred to the ultraviolet ozone treatment chamber to perform ultraviolet ozone treatment on the halide inorganic phase layer.

[0036] S4. Deposit organic salts on the halide inorganic phase layer after ultraviolet ozone treatment, and anneal the substrate on which organic salts are deposited to form a perovskite film.

[0037] This application solves the problem of poor permeability of organic salt solutions on the surface of dense inorganic phase layers by subjecting the halide inorganic phase layer to ultraviolet ozone (UVO) treatment after the preparation of the inorganic phase layer and before the deposition of organic salts. This prevents premature formation of perovskite on the upper surface from blocking subsequent permeation reactions. It effectively reduces or eliminates unreacted metal halides at the buried interface of the perovskite film, reducing their negative impact on device performance as non-radiative recombination centers. It significantly improves the physical permeation rate of the organic phase solution and the intrinsic reaction rate of perovskite nucleation and growth. This fundamentally solves the technical problems of incomplete reaction and residual metal halide at the bottom interface in the two-step method combining thermal evaporation and solution deposition, achieving high film quality and low-cost preparation for large-area perovskite film preparation.

[0038] On the one hand, UV ozone treatment cleans and oxidizes the surface of the halide inorganic phase layer, increasing its surface energy and hydrophilicity. This significantly reduces the contact angle of the organic phase solution, enhances capillary driving force, improves the wettability and capillary permeation efficiency of the organic phase solution, and increases its permeation rate. On the other hand, the high-energy ultraviolet light and active oxides in UVO treatment can slightly etch the surface of the halide inorganic phase layer, expanding the pore size of its surface nanopores and enhancing pore connectivity. This further reduces the flow resistance of the organic phase solution and increases the longitudinal and transverse permeation rates of the organic phase solution in the halide inorganic phase layer.

[0039] For a detailed explanation of the mechanism, please refer to the Washburn equation describing the permeation rate (the following explanation uses lead halide as an example):

[0040] ;

[0041] In the equation: L is the penetration depth, γ is the surface tension of the liquid, R is the effective pore radius of the halide inorganic phase layer, θ is the contact angle (wettability) between the organic phase solution and the lead halide inorganic phase layer, η is the viscosity of the organic phase solution, t is time, and dL / dt is the penetration rate.

[0042] (1) The surface energy of the untreated lead halide inorganic phase layer is low, resulting in poor wettability and a large contact angle for polar organic phase solutions. According to capillary theory, the capillary driving force (proportional to cosθ) is weak at this time, causing the organic phase solution to mainly rely on slow diffusion to contact and react with the lead halide layer, resulting in low permeation efficiency.

[0043] After UVO treatment, its strong oxidizing effect efficiently decomposes the trace organic matter adsorbed on the surface of the lead halide inorganic phase layer during preparation and transfer. More importantly, during this oxidation process, a chemisorption layer rich in polar functional groups such as -OH and -COOH is formed on the lead halide surface. This modified layer causes its surface energy to change from a low energy state to a high energy state, and the contact angle is significantly reduced to a superhydrophilic state. This increases the capillary force (cosθ value) from a small value to a large value, thereby transforming the weak permeation driving force into a strong permeation driving force, and thus improving the permeation rate of the organic phase solution.

[0044] (2) In UVO treatment, high-energy ultraviolet light and active oxides can perform slight physical etching on the surface of the inorganic phase layer of lead halide, expand the pore size of the surface nanopores, increase the connectivity of the pores, increase the effective pore radius R, reduce the flow resistance of the organic phase solution, and according to the Washburn equation, the permeation rate will also increase.

[0045] (3) Since UVO is used to post-treat the inorganic phase layer of lead halide, no high viscosity additives are introduced into the organic phase solution, and the viscosity η and liquid surface tension γ of the organic phase solution remain unchanged.

[0046] As can be seen from (1)-(3) above, γ and η remain unchanged, the effective pore radius R increases, cosθ increases, and therefore the dL / dt permeation rate increases.

[0047] On the other hand, the highly active defect sites created by ultraviolet ozone treatment effectively reduce the activation energy of solid-liquid reactions, thereby increasing the intrinsic reaction rate of perovskite nucleation and growth. Metal halides (e.g., PbI2) possess highly ordered ionic bonds, and Pb... 2+ and I - In a low-energy steady state, a large amount of energy is required to disrupt this steady state in order to react with the organic phase. UVO treatment can generate defect sites such as I vacancies and Pb clusters, placing the metal halide in a coordinated unsaturated state with numerous dangling bonds and high surface energy, making it thermodynamically unstable. Organic cations (such as FA...) + MA + It will preferentially adsorb at defect sites, without having to overcome the Pb-I chemical bond energy, thus reducing the activation energy of the reaction and increasing the intrinsic reaction rate of perovskite nucleation and growth.

[0048] The solid-liquid reaction rate can be referenced using the Arrhenius equation:

[0049] ;

[0050] In the formula: k is the reaction rate constant, A is the characteristic constant (a constant value here), Ea is the activation energy, R is the gas constant, and T is the temperature.

[0051] Because UVO treatment of the inorganic lead halide layer results in strong capillary penetration and a smoother penetration path, the rate at which the organic phase solution penetrates and transports reactants into the inorganic lead halide layer exceeds the rate at which the organic phase solution is consumed on the surface of the inorganic lead halide layer. This leads to a significant decrease in the instantaneous concentration and total amount of the solution remaining per unit area on the surface of the inorganic lead halide layer due to rapid diffusion. As a result, the organic phase solution has completely penetrated into the entire inorganic lead halide layer before the formation of the surface barrier layer. This enables the metal halides at all points in the inorganic lead halide layer to react with the organic phase. In other words, the time difference between the organic solution penetration rate and the surface barrier layer formation rate ensures that the inorganic lead halide layer is completely transformed into perovskite from top to bottom. This fundamentally eliminates the problem of metal halide residue at the buried interface caused by the inability of organic reactants to be transported to the bottom layer of the inorganic lead halide layer. This produces a perovskite film with no metal halide residue, high density, and high quality, thereby improving the photoelectric performance and stability of the battery.

[0052] The perovskite thin film preparation method provided in this application only requires UVO treatment of the halide inorganic phase layer before coating with the organic phase solution. It does not require the introduction of additional evaporation sources and vapor deposition components, nor does it require solvent treatment of the inorganic phase layer or the introduction of other additives and solvents into the organic phase solution. This ensures the uniformity of the distribution of the organic phase solution during large-area coating, improves the film quality when preparing perovskite thin films over large areas, and enhances product consistency and yield. Furthermore, it is highly compatible with existing vacuum vapor deposition-solution methods. The preparation method is simple and easy to implement, significantly reducing the cost of preparing perovskite thin films over large areas.

[0053] Compared to the traditional method of additional PbCl2 evaporation, the technical solution provided in this application does not require an additional evaporation source and does not introduce additional components that could lead to uncontrollable thin films. Compared to the traditional method of treating the inorganic phase layer with solvents, the technical solution provided in this application overcomes the problems of solvent residue and secondary dissolution of the inorganic layer that may result from solvent treatment, which could damage the morphology. Compared to the traditional method of treating the perovskite inorganic layer with solvent vapor, the technical solution provided in this application solves the technical problems that solvent vapor treatment may excessively soften or damage the crystalline structure of the inorganic layer, leading to a decrease in the mechanical strength of the thin film and damage to its long-term stability. Compared to the traditional method of using mixed solvents, including proton polar solvents and non-proton polar solvents, to dissolve organic salts, the technical solution provided in this application solves the technical defects of poor homogeneity caused by the difference in volatility of mixed solvents under large-area film formation conditions.

[0054] In some embodiments, the preparation of the halide inorganic phase layer in S2 above includes the following steps:

[0055] The substrate and halide material are placed in a vacuum chamber and heated to evaporate, forming a halide inorganic phase layer on the substrate.

[0056] It is understood that the term "substrate" in this application refers to an intermediate component for constructing a perovskite thin film before the completion of the front-end device structure, including a carrier transport layer, conductive glass, a bottom cell, etc., without specific limitations. For example, the substrate may include a conductive substrate and a hole transport layer stacked sequentially; or the substrate may include a conductive substrate and an electron transport layer stacked sequentially; or the substrate may include a crystalline silicon bottom cell, a tunneling layer, and a hole transport layer stacked sequentially; or the substrate may include a crystalline silicon bottom cell, a tunneling layer, and an electron transport layer stacked sequentially.

[0057] This application does not impose any particular limitation on the specific types of conductive substrates, hole transport layers, electron transport layers, crystalline silicon bottom cells, and tunneling layers. Provided that the overall inventive concept of this application is satisfied, any known conductive substrate, hole transport layer, electron transport layer, crystalline silicon bottom cell, and tunneling layer can be applied to this application. The following are merely examples:

[0058] The conductive substrate includes conductive glass, including but not limited to at least one of ITO (indium tin oxide), IZO (indium zinc oxide), FTO (fluorine-doped tin oxide), AZO (aluminum-doped zinc oxide), IWO (tungsten-doped indium oxide), and IZrO (indium zirconium oxide).

[0059] The base cell includes crystalline silicon sub-cells or perovskite sub-cells. Crystalline silicon sub-cells include, but are not limited to, one of PERC, TOPCon, HJT, IBC, HBC, and TBC, for absorbing long-wavelength sunlight.

[0060] The tunneling layer includes, but is not limited to, at least one of ITO, IZO, IWO and IZrO.

[0061] Hole transport layers include, but are not limited to, NiO X At least one of PTAA, poly-TPD, PEDOT:PSS, spiro-TTB, and carbazole phosphate-containing self-assembled molecules.

[0062] Electron transport layers include, but are not limited to, SnO X At least one of TiO2, ZnO, PCBM, C60 and their derivatives.

[0063] In some embodiments, the halide inorganic phase layer comprises lead halide or cesium halide. It is understood that lead halide includes at least one of lead chloride (PbCl2), lead bromide (PbBr2), and lead iodide (PbI2). Cesium chloride, cesium bromide, and cesium iodide are also included. The preparation process of the halide inorganic phase layer includes a single evaporation process or a co-evaporation process.

[0064] In some embodiments, the halide inorganic phase layer includes lead iodide. That is, the halide inorganic phase layer includes only lead iodide, or the halide inorganic phase layer includes lead iodide and other components.

[0065] In some embodiments, the halide inorganic phase layer further includes at least one of lead chloride, lead bromide, cesium chloride, cesium bromide, and cesium iodide.

[0066] In some embodiments, the evaporation rate of lead iodide is 1 Å / s to 5 Å / s, including but not limited to 1 Å / s, 2 Å / s, 3 Å / s, 4 Å / s, and 5 Å / s.

[0067] In some embodiments, the evaporation rates of lead chloride, lead bromide, cesium chloride, cesium bromide and cesium iodide are each independently 0.1 Å / s to 1.2 Å, including but not limited to 0.1 Å / s, 0.2 Å / s, 0.4 Å / s, 0.6 Å / s, 0.8 Å / s, 1 Å / s and 1.2 Å / s.

[0068] In some embodiments, the thickness of the halide inorganic phase layer is 200 nm to 700 nm, including but not limited to 200 nm, 300 nm, 400 nm, 500 nm, and 700 nm. Further, the thickness of the halide inorganic phase layer is 200 nm to 500 nm.

[0069] The inorganic phase layer is transferred to a UV ozone treatment chamber, a UV light source is turned on, and oxygen is introduced to treat the halide inorganic phase layer with UV ozone. Through UV ozone treatment, the surface of the halide inorganic phase layer is modified to increase its surface energy and hydrophilicity, expand the pore size of surface nanopores, increase pore connectivity, enhance the permeation rate of the organic phase solution, increase the number of highly active defect sites on the surface, and reduce the activation energy of solid-liquid reactions.

[0070] In some embodiments, the ultraviolet light wavelength in the ultraviolet ozone treatment is 185 nm and / or 254 nm.

[0071] In some embodiments, the power density of ultraviolet light in ultraviolet ozone treatment is 10 mW / cm². 2 ~120mW / cm 2 including but not limited to 10mW / cm 2 30mW / cm 2 50mW / cm 2 70mW / cm 2 90mW / cm 2 120mW / cm 2 Furthermore, the power density of the ultraviolet light is 20 mW / cm². 2 ~80mW / cm 2By setting the power density of ultraviolet light within the aforementioned range, sufficient energy is provided to drive the photochemical reaction, promoting ozone generation, increasing the surface reaction rate, reducing processing time, and improving production efficiency; at the same time, excessive oxidation or physical sputtering damage to the surface of the halide inorganic phase layer is avoided, thus reducing energy consumption.

[0072] In some embodiments, the oxygen flow rate in ultraviolet ozone treatment is 0.1 L / min to 3 L / min, including but not limited to 0.1 L / min, 0.5 L / min, 1 L / min, 2 L / min, and 3 L / min. Further, the oxygen flow rate is 0.2 L / min to 2.5 L / min. By setting the oxygen flow rate, sufficient ozone concentration is ensured, improving treatment efficiency while avoiding gas waste caused by excessive flow, thus improving the stability of the airflow and temperature fields in the cavity, and consequently improving treatment uniformity.

[0073] In some embodiments, the temperature for ultraviolet ozone treatment is 50°C to 100°C, including but not limited to 50°C, 60°C, 70°C, 80°C, 90°C, and 100°C. Further, the temperature is 60°C to 80°C. By setting the temperature for ultraviolet ozone treatment, the reaction kinetics are improved, while ensuring the reactivity of the subsequent halide inorganic phase layer and organic salt.

[0074] In some embodiments, the ultraviolet ozone treatment time is 5s to 600s, including but not limited to 5s, 50s, 100s, 200s, 300s, 400s, 500s, and 600s. Further, the treatment time is 5s to 30s. By setting the treatment time within the above range, excessive treatment that could lead to excessive surface damage is avoided, while ensuring the surface modification effect.

[0075] In some embodiments, the distance between the surface of the halide inorganic phase layer and the ultraviolet lamp is 1cm to 25cm, including but not limited to 1cm, 5cm, 10cm, 20cm, and 25cm. Further, the distance between the surface of the halide inorganic phase layer and the ultraviolet lamp is 3cm to 20cm. If the distance is too close, the local light intensity is too high, which can easily lead to uneven processing (excessive intensity in the center and weak intensity at the edges) and poses a risk of thermal damage. If the distance is too far, the light intensity attenuates severely, the effective power density is insufficient, the processing effect is weak, and the processing time is longer. Therefore, this application improves processing uniformity, avoids thermal damage, and increases processing efficiency by precisely adjusting the distance between the ultraviolet lamp and the sample surface, thereby reducing the local energy density and distributing it evenly.

[0076] In some embodiments, the step of depositing organic salt on the halide inorganic phase layer after ultraviolet ozone treatment and annealing the substrate on which the organic salt is deposited to form a perovskite thin film in S4 includes the following steps:

[0077] S41. Dissolve the organic salt in an organic solvent to prepare an organic phase solution.

[0078] S42. Coat the organic phase solution onto the halide inorganic phase layer, and deposit organic salts on the halide inorganic phase layer.

[0079] S43. Anneal the substrate on which organic salts are deposited to form a perovskite film.

[0080] In some embodiments, the organic salt is a halogenated organic salt.

[0081] In some embodiments, the organic salt includes at least one of methylammonium iodide (MAI), methylammonium bromide (MABr), methylammonium chloride (MACl), formamidine iodide (FAI), formamidine bromide (FABr), formamidine chloride (FACl), dimethylammonium iodide (DMAI), dimethylammonium bromide (DMABr), and dimethylammonium chloride (DMACl).

[0082] In some embodiments, the organic solvent includes at least one selected from isopropanol, methanol, ethanol, n-butanol, isobutanol, acetonitrile, γ-butyrolactone, γ-valerolactone, N,N-dimethylformamide, and dimethyl sulfoxide.

[0083] In some embodiments, the solute concentration in the organic phase solution is 0.3M to 0.7M, including but not limited to 0.3M, 0.4M, 0.5M, 0.6M, and 0.7M.

[0084] In some embodiments, the coating method for coating an organic phase solution onto a halide inorganic phase layer includes, but is not limited to, spin coating, inkjet printing, spraying, slot coating, blade coating, and immersion coating, at least one of these methods.

[0085] In one specific embodiment, an organic salt is dissolved in an organic solvent, heated and stirred, and then filtered to prepare an organic phase solution.

[0086] In some embodiments, the heating and stirring temperature is 50°C to 70°C, including but not limited to 50°C, 60°C, and 70°C.

[0087] In some embodiments, the heating and stirring time is 30 min to 120 min, including but not limited to 30 min, 50 min, 70 min, 90 min, 100 min, and 120 min.

[0088] In one specific embodiment, a filter head with a diameter of 0.22 μm or 0.45 μm is used for filtration.

[0089] In some embodiments, the annealing temperature is 80°C to 120°C, including but not limited to 80°C, 90°C, 100°C, 110°C, and 120°C.

[0090] In some implementations, the annealing time is 3 min to 30 min, including but not limited to 3 min, 10 min, 20 min, and 30 min.

[0091] In one specific embodiment, 50 μL to 200 μL of organic phase solution is dropped onto a halide inorganic phase layer treated with UVO. After standing for 3 to 20 seconds, the solution is rotated at a speed of 1000 rpm / min to 4000 rpm / min for 15 to 30 seconds in a nitrogen or air environment and then annealed to deposit the organic salt onto the halide inorganic phase layer, thus preparing a perovskite thin film.

[0092] In some embodiments, the thickness of the perovskite film is 400nm to 800nm, including but not limited to 400nm, 500nm, 600nm, 700nm, and 800nm.

[0093] The second aspect of this application provides a perovskite thin film, which is prepared using the perovskite thin film preparation method provided in the first aspect of this application.

[0094] The third aspect of this application provides a perovskite solar cell, including a perovskite thin film prepared by the method for preparing perovskite thin films as provided in the first aspect of this application or a perovskite thin film provided in the second aspect of this application.

[0095] It is understood that the perovskite solar cell in this application can be a single-junction perovskite solar cell or a tandem perovskite solar cell.

[0096] like Figure 2 As shown, in one specific embodiment, a perovskite solar cell includes a conductive substrate, a first carrier transport layer, a perovskite thin film, a second carrier transport layer, a transparent conductive oxide layer, and a metal electrode layer, which are sequentially stacked. The conductive substrate and the first carrier transport layer constitute a substrate. The first carrier transport layer and the second carrier transport layer are each independently selected from one of a hole transport layer and an electron transport layer, and the first carrier transport layer and the second carrier transport layer are different.

[0097] The perovskite solar cell in this application can also be a tandem perovskite solar cell, such as a crystalline silicon-perovskite tandem solar cell or an all-perovskite tandem cell.

[0098] like Figure 3 As shown, in one specific embodiment, the perovskite solar cell is a crystalline silicon-perovskite tandem solar cell, comprising a transparent conductive oxide layer, a perovskite top cell, a charge recombination layer, a crystalline silicon bottom cell, and a back electrode stacked sequentially.

[0099] In some embodiments, this application provides a method for fabricating a perovskite solar cell, comprising the following steps:

[0100] S100. Using the preparation method provided in the first aspect of this application, a perovskite thin film is prepared on a substrate; the substrate includes a conductive substrate and a first carrier transport layer stacked together.

[0101] S200, a second carrier transport layer is formed on the perovskite thin film.

[0102] S300, a buffer layer is formed on the second carrier transport layer.

[0103] S400, A transparent conductive oxide layer is formed on the buffer layer.

[0104] S500: A metal electrode layer is formed on a transparent conductive oxide layer.

[0105] The first carrier transport layer and the second carrier transport layer are each independently selected from either the hole transport layer or the electron transport layer, and the first carrier transport layer and the second carrier transport layer are different.

[0106] For example, a second carrier transport layer is formed on a perovskite thin film using a vapor deposition process.

[0107] For example, the preparation methods of the buffer layer include, but are not limited to, at least one of atomic layer deposition, vapor deposition, spin coating, blade coating, and slot coating.

[0108] In some implementations, a BCP buffer layer is formed on the second carrier transport layer using a vapor deposition process.

[0109] In some implementations, SnO is formed on the second carrier transport layer using an ALD process. X Buffer layer.

[0110] For example, the transparent conductive oxide layer can be prepared by at least one of magnetron sputtering, pulsed laser deposition, chemical vapor deposition, atomic layer deposition, and reactive plasma deposition.

[0111] In one specific embodiment, a transparent conductive oxide layer is formed on the buffer layer using a magnetron sputtering process. The transparent conductive oxide layer includes, but is not limited to, at least one of ITO (indium tin oxide), IZO (indium zinc oxide), FTO (fluorine-doped tin oxide), AZO (aluminum-doped zinc oxide), IWO (tungsten-doped indium oxide), and IZrO (indium zirconium oxide).

[0112] In some embodiments, the metal electrode layer includes, but is not limited to, one or more of Ag, Cu, Al, Au, Ni, and Cr, for transferring charge to an external circuit.

[0113] For example, the metal electrode layer can be prepared by at least one of screen printing, electroplating, inkjet printing and vapor deposition.

[0114] A fourth aspect of this application provides a photovoltaic module, including the perovskite solar cell provided in the third aspect of this application.

[0115] The present application will be further described below with reference to specific embodiments and comparative examples.

[0116] Example 1

[0117] (1) Preparation of substrate: 0.4 mg / mL 2PACz precursor solution was spin-coated on ITO conductive substrate. The solvent was ethanol. The spin-coating speed was 2500 rpm and the time was 25 s. After spin-coating, the substrate was placed on a heating stage for annealing at 100℃ for 10 min to form a hole transport layer with a thickness of 2 nm on the ITO conductive substrate.

[0118] (2) Preparation of perovskite thin film: The substrate and the PbI2 material to be deposited were placed in a vacuum chamber. The substrate was fixed on a sample holder, and the PbI2 material was placed in an evaporation boat. Heating was performed to evaporate the PbI2 material onto the substrate at an evaporation rate of 2 Å / s, forming a 400 nm thick halide inorganic phase layer. The halide inorganic phase layer formed on the substrate was then placed in a UVO chamber for UVO treatment. The wavelengths of the ultraviolet light were 185 nm and 254 nm, and the power density was 50 mW / cm². 2 The inorganic phase layer was prepared by placing the distance between the inorganic phase layer and the ultraviolet lamp at 5 cm, the oxygen flow rate at 1 L / min, the sample substrate temperature at 80 °C, and the treatment time at 10 s.

[0119] FAI and MACl in a molar ratio of 1:0.3 were dissolved in isopropanol and heated and stirred at 70°C for 30 min. The mixture was then filtered through a 0.22 μm filter to obtain an organic phase solution with a solute concentration of 0.4 M. 100 μL of the organic phase solution was dropped onto the inorganic phase layer after UV ozone treatment. The mixture was allowed to stand for 10 s, then rotated at 3000 rpm / min for 20 s under nitrogen atmosphere and annealed at 100°C for 15 min to prepare a perovskite film with a thickness of 500 nm.

[0120] (3) Preparation of electron transport layer: A 20 nm C60 electron transport layer was prepared on the perovskite thin film by vapor deposition process.

[0121] (4) Preparation of buffer layer: 10 nm SnO was prepared on the C60 electron transport layer using ALD process. X Buffer layer.

[0122] (5) Preparation of transparent conductive oxide layer: in SnO X A 30 nm IZO transparent conductive oxide layer was fabricated on the buffer layer.

[0123] (6) Preparation of metal electrode layer: A 200 nm Cu electrode was prepared on the IZO transparent conductive oxide layer by vapor deposition. The perovskite solar cell was thus obtained.

[0124] Example 2

[0125] The preparation process in this embodiment is basically the same as that in Example 1, with the main difference being in this embodiment:

[0126] Step (2) is as follows: Preparation of the perovskite thin film: The substrate, the PbI2 material to be deposited, the CsI material to be deposited, and the PbBr2 material to be deposited are placed in a vacuum chamber, with PbI2 as the main evaporation source and CsI and PbBr2 as secondary evaporation sources. A ternary co-evaporation method is used to deposit the PbI2, CsI, and PbBr2 materials onto the substrate at evaporation rates of 2 Å / s, 0.2 Å / s, and 0.1 Å / s, respectively, forming an inorganic phase layer with a thickness of 400 nm. The organic phase is an isopropanol solution with a FAI:MABr:MACl molar ratio of 10:1:1.

[0127] Example 3

[0128] The preparation process of this embodiment is basically the same as that of Example 2. The main difference is that in this embodiment, the thickness of the inorganic phase layer is 500 nm, the concentration of the organic phase is 0.5 M, and the final thickness of the perovskite is 600 nm.

[0129] Comparative Example 1

[0130] The preparation process of this comparative example is basically the same as that of Example 1. The main difference is that the inorganic phase layer was not treated with UVO in this comparative example.

[0131] Comparative Example 2

[0132] The preparation process of this comparative example is basically the same as that of Example 2, except that the inorganic phase layer was not treated with UVO in this comparative example.

[0133] Comparative Example 3

[0134] The preparation process of this comparative example is basically the same as that of Example 2. The main difference is that in this comparative example, the step of UVO treatment of the inorganic phase layer in Example 2 is replaced by treating the inorganic phase layer with 200 μL of mixed solvent (n-butanol: N-methylpyrrolidone = 95:5). The mixed solvent is dropped onto the inorganic phase layer in a glove box using a spin coater, and then the coating is carried out at a speed of 4000 rpm for 30 s, followed by annealing at 100°C for 5 min.

[0135] Comparative Example 4

[0136] The preparation process of this comparative example is basically the same as that of Example 2. The main difference is that in this comparative example, the step of treating the inorganic phase layer with UVO in Example 2 is replaced with treating the inorganic phase layer with DMSO steam for 30 seconds.

[0137] Comparative Example 5

[0138] The preparation process of this comparative example is basically the same as that of Example 2. The main difference is that in this comparative example, the inorganic phase layer was not treated with UVO, and the solvent of the organic phase solution is isopropanol and N,N-dimethylformamide in a volume ratio of 1:20.

[0139] Comparative Example 6

[0140] The preparation process of this comparative example is basically the same as that of Example 3, except that the inorganic phase layer was not treated with UVO in this comparative example.

[0141] Test case

[0142] (1) Photovoltaic conversion performance test: The solar cells made in the above examples and comparative examples were placed in a solar simulator (manufacturer: Wavelabs). Under the illumination of a certain solar intensity, a bias voltage (Vp, bias voltage range of -0.1 V to 2.1 V) was applied to the device using a test source meter and the output current of the device was tested to obtain the bias voltage-current density curve.

[0143] Open-circuit voltage (Voc): The terminal voltage of the solar cell when no load is connected, i.e., when the current density in the bias-current density curve is 0 mA·cm. -2 The bias voltage value at that time.

[0144] Short-circuit current density (Jsc): The output current per unit area of ​​the solar cell when it is short-circuited, i.e., the current density when the bias voltage is 0V in the bias voltage-current density curve.

[0145] Fill factor (FF): FF = max(Vp × Jsc), where Vp is the bias voltage and Jsc is the short-circuit current density.

[0146] Photovoltaic cell efficiency (PCE): PCE = Voc × Jsc × FF. The test results are shown in Table 1.

[0147] (2) Long-term stability test: After the solar cells prepared in the above examples and comparative examples were placed for 1000 hours, the PCE retention rate was tested. The test results are shown in Table 1.

[0148] (3) Contact Angle Test: The inorganic phase layers used in the above examples and comparative examples, both with and without UVO treatment, were used as samples. An organic phase solution (FAI and MACl in a molar ratio of 1:0.3 or FAI, MABr, and MACl in a molar ratio of 10:1:1 dissolved in isopropanol, heated and stirred at 70°C for 30 min, and then filtered through a 0.22 μm filter) was dropped onto its surface, and the corresponding contact angle was observed. The smaller the contact angle, the better the spreading, and the easier it is for the organic phase solution to penetrate into the inorganic phase. The test results are shown in Table 1.

[0149] Table 1

[0150]

[0151] Based on the comparison of Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, Example 3 and Comparative Example 6, it can be seen that by treating the inorganic phase layer with ultraviolet ozone, the contact angle of the organic phase solution is significantly reduced, the capillary driving force is improved, the wettability and capillary permeation efficiency of the organic phase solution are improved, and the photoelectric performance and stability of the battery are significantly enhanced.

[0152] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0153] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a perovskite thin film, characterized in that, Includes the following steps: Provide a base; A halide inorganic phase layer was prepared by thermal evaporation on the substrate; The halide inorganic phase layer formed on the substrate is transferred to the ultraviolet ozone treatment chamber for ultraviolet ozone treatment. An organic salt is deposited on the halide inorganic phase layer after ultraviolet ozone treatment, and the substrate on which the organic salt is deposited is annealed to form a perovskite film.

2. The method for preparing perovskite thin films according to claim 1, characterized in that, The halide inorganic phase layer includes lead iodide.

3. The method for preparing perovskite thin films according to claim 2, characterized in that, The halide inorganic phase layer further includes at least one of lead chloride, lead bromide, cesium chloride, cesium bromide, and cesium iodide.

4. The method for preparing perovskite thin films according to claim 3, characterized in that, The thickness of the halide inorganic phase layer is 200 nm to 700 nm.

5. The method for preparing perovskite thin films according to any one of claims 1-4, characterized in that, The ultraviolet ozone treatment meets at least one of the following conditions: (1) The ultraviolet light wavelength is 185 nm and / or 254 nm; (2) The power density of ultraviolet light is 10 mW / cm². 2 ~120mW / cm 2 .

6. The method for preparing perovskite thin films according to any one of claims 1-4, characterized in that, The oxygen flow rate in the ultraviolet ozone treatment is 0.1 L / min to 3 L / min.

7. The method for preparing perovskite thin films according to any one of claims 1-4, characterized in that, The temperature in the ultraviolet ozone treatment is 50℃~100℃.

8. A perovskite thin film, characterized in that, The perovskite thin film was prepared using the method described in any one of claims 1-7.

9. A perovskite solar cell, characterized in that, Includes the perovskite thin film as described in claim 8.

10. A photovoltaic module, characterized in that, Including the perovskite solar cell of claim 9.

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